the ancient life-history of the earth a comprehensive outline of the principles and leading facts of palÆontological science by h. alleyne nicholson m.d., d.sc., m.a., ph. d. (gÖtt), f.r.s.e, f.l.s. professor of natural history in the university of st andrews preface. the study of palæontology, or the science which is concerned with the living beings which flourished upon the globe during past periods of its history, may be pursued by two parallel but essentially distinct paths. by the one method of inquiry, we may study the anatomical characters and structure of the innumerable extinct forms of life which lie buried in the rocks simply as so many organisms, with but a slight and secondary reference to the _time_ at which they lived. by the other method, fossil animals are regarded principally as so many landmarks in the ancient records of the world, and are studied _historically_ and as regards their relations to the chronological succession of the strata in which they are entombed. in so doing, it is of course impossible to wholly ignore their structural characters, and their relationships with animals now living upon the earth; but these points are held to occupy a subordinate place, and to require nothing more than a comparatively general attention. in a former work, the author has endeavoured to furnish a summary of the more important facts of palæontology regarded in its strictly scientific aspect, as a mere department of the great science of biology. the present work, on the other hand, is an attempt to treat palæontology more especially from its historical side, and in its more intimate relations with geology. in accordance with this object, the introductory portion of the work is devoted to a consideration of the general principles of palæontology, and the bearings of this science upon various geological problems--such as the mode of formation of the sedimentary rocks, the reactions of living beings upon the crust of the earth, and the sequence in time of the fossiliferous formations. the second portion of the work deals exclusively with historical palæontology, each formation being considered separately, as regards its lithological nature and subdivisions, its relations to other formations, its geographical distribution, its mode of origin, and its characteristic life-forms. in the consideration of the characteristic fossils of each successive period, a general account is given of their more important zoological characters and their relations to living forms; but the technical language of zoology has been avoided, and the aid of illustrations has been freely called into use. it may therefore be hoped that the work may be found to be available for the purposes of both the geological and the zoological student; since it is essentially an outline of historical palæontology, and the student of either of the above-mentioned sciences must perforce possess some knowledge of the last. whilst primarily intended for students, it may be added that the method of treatment adopted has been so far untechnical as not to render the work useless to the general reader who may desire to acquire some knowledge of a subject of such vast and universal interest. in carrying out the object which he has held before him, the author can hardly expect, from the nature of the materials with which he has had to deal, that he has kept himself absolutely clear of errors, both of omission and commission. the subject, however, is one to which he has devoted the labour of many years, both in studying the researches of others and in personal investigations of his own; and he can only trust that such errors as may exist will be found to belong chiefly to the former class, and to be neither serious nor numerous. it need only be added that the work is necessarily very limited in its scope, and that the necessity of not assuming a thorough previous acquaintance with natural history in the reader has inexorably restricted its range still further. the author does not, therefore, profess to have given more than a merely general outline of the subject; and those who desire to obtain a more minute and detailed knowledge of palæontology, must have recourse to other and more elaborate treatises. united college, st andrews. october , . contents. part i. principles of palÆontology. introduction. the general objects or geological science--the older theories of catastrophistic and intermittent action--the more modern doctrines of continuous and uniform action--bearing of these doctrines respectively on the origin or the existing terrestrial order--elements or truth in catastrophism--general truth of the doctrine of continuity--geological time. chapter i. definition of palæontology--nature of fossils--different processes of fossilisation. chapter ii. aqueous and igneous rocks--general characters of the sedimentary rocks--mode or formation of the sedimentary rocks--definition of the term "formation"--chief divisions of the aqueous rocks--mechanically-formed rocks, their characters and mode of origin--chemically and organically formed rocks--calcareous rocks--chalk, its microscopic structure and mode of formation--limestone, varieties, structure, and origin--phosphate of lime--concretions--sulphate of lime--silica and siliceous deposits of various kinds--greensands--red clays--carbon and carbonaceous deposits. chapter iii. chronological succession of the fossiliferous rocks--tests or age of strata--value of palæontological evidence in stratigraphical geology--general sequence of the great formations. chapter iv. the breaks in the palæontological and geological record--use of the term "contemporaneous" as applied to groups of strata--general sequence of strata and of life-forms interfered with by more or less extensive gaps--unconformability--phenomena implied by this--causes of the imperfection of the palæontological record. chapter v. conclusions to be drawn from fossils--age of rocks--mode of origin of any fossiliferous bed--fluviatile, lacustrine, and marine deposits--conclusions as to climate--proofs of elevation and subsidence of portions of the earth's crust derived from fossils. chapter vi. the biological relations of fossils--extinction of life-forms--geological range of different species--persistent types of life--modern origin of existing animals and plants--reference of fossil forms to the existing primary divisions of the animal kingdom--departure of the older types of life from those now in existence--resemblance of the fossils of a given formation to those of the formation next above and next below--introduction of new life-forms. part ii. historical palÆontology. chapter vii. the laurentian and huronian periods--general nature, divisions, and geographical distribution of the laurentian deposits--lower and upper laurentian--reasons for believing that the laurentian rocks are not azoic based upon their containing limestones, beds of oxide of iron, and graphite--the characters, chemical composition, and minute structure of _eozoön canadense_--comparison of _eozoön_ with existing foraminifera--_archoeosphoerinoe_--huronian formation--nature and distribution of huronian deposits--organic remains of the huronian--literature. chapter viii. the cambrian period--general succession of cambrian deposits in wales--lower cambrian and upper cambrian--cambrian deposits of the continent of europe and north american--life of the cambrian period--fucoids--eophyton--oldhamia--sponges--echinoderms--annelides --crustaceans--structure of trilobites--brachiopods--pteropods, gasteropods, and bivalves--cephalopods--literature. chapter ix. the lower silurian period--the silurian rocks generally--limits of lower and upper silurian--general succession, subdivisions, and characters of the lower silurian rocks of wales--general succession, subdivisions, and characters of the lower silurian rocks of the north american continent--life of the period--fucoids--protozoa--graptolites--structure of graptolites--corals--general structure of corals--crinoids-- cystideans--general characters of cystideans--annelides-- crustaceans--polyzoa--brachiopods--bivalve and univalve molluscs--chambered cephalopods--general characters of the cephalopoda--conodonts. chapter x. the upper silurian period--general succession of the upper silurian deposits of wales--upper silurian deposits of north america--life of the upper silurian--plants--protozoa--graptolites--corals-- crinoids--general structure of crinoids--star-fishes--annelides-- crustaceans--eurypterids--polyzoa--brachiopods--structure of brachiopods--bivalves and univalves--pteropods--cephalopods-- fishes--silurian literature. chapter xi. the devonian period--relations between the old red sandstone and the marine devonian deposits--the old red sandstone of scotland--the devonian strata of devonshire--sequence and subdivisions of the devonian deposits of north america--life of the period--plants--protozoa--corals-crinoids--pentremites-- annelides--crustaceans--insects--polyzoa--brachiopods--bivalves-- univalves--pteropods--cephalopods--fishes--general divisions of the fishes--palæontological evidence as to the independent existence of the devonian system as a distinct formation--literature. chapter xii. the carboniferous period--relations of carboniferous rocks to devonian--the carboniferous limestone or sub-carboniferous series--the millstone-grit and the coal-measures--life of the period--structure and mode of formation of coal--plants of the coal. chapter xiii. animal life of the carboniferous period--protozoa--corals-- crinoids--pentremites--structure of pentremites--echinoids-- structure of echinoidea--annelides--crustacea--insects-- arachnids--myriapods--polyzoa--brachiopods--bivalves and univalves--cephalopods--fishes--labyrinthodont amphibians-- literature. chapter xiv. the permian period--general succession, characters, and mode of formation of the permian deposits--life of the period-- plants--protozoa--corals--echinoderms--annelides--crustaceans-- polyzoa--brachiopods--bivalves-univalves--pteropods-- cephalopods--fishes--amphibians--reptiles--literature. chapter xv. the triassic period--general characters and subdivisions of the trias of the continent of europe and britain--trias of north america--life of the period--plants--echinoderms--crustaceans-- polyzoa--brachiopods--bivalves--univalves--cephalopods-- intermixture of palæozoic with mesozoic types of molluscs-- fishes--amphibians--reptiles--supposed footprints of birds-- mammals--literature. chapter xvi. the jurassic period--general sequence and subdivisions of the jurassic deposits in britain--jurassic rocks of north america--life of the period--plants--corals--echinoderms--crustaceans--insects-- brachiopods--bivalves--univalves-pteropods--tetrabranchiate cephalopods--dibranchiate cephalopods--fishes--reptiles--birds-- mammals--literature. chapter xvii. the cretaceous period--general succession and subdivisions of the cretaceous rocks in britain--cretaceous rocks of north america--life of the period--plants--protozoa--corals--echinoderms-- crustaceans--polyzoa--brachiopods--bivalves--univalves-- tetrabranchiate and dibranchiate cephalopods--fishes--reptiles-- birds--literature. chapter xviii. the eocene period--relations between the kainozoic and mesozoic rocks in europe and in north america--classification of the tertiary deposits--the sequence and subdivisions of the eocene rocks of britain and france--eocene strata of the united states--life of the period--plants--foraminifera--corals--echinoderms--mollusca--fishes-- reptiles--birds--mammals. chapter xix. the miocene period--miocene strata of britain--of france--of belgium--of austria--of switzerland--of germany--of greece--of india--of north america--of the arctic regions--life of the period--vegetation of the miocene period--foraminifera--corals-- echinoderms--articulates--mollusca--fishes-amphibians--reptiles-- mammals. chapter xx. the pliocene period--pliocene deposits of britain--of europe--of north america--life of the period--climate of the period as indicated by the invertebrate animals--the pliocene mammalia--literature relating to the tertiary deposits and their fossils. chapter xxi. the post-pliocene period--division of the quaternary deposits into post-pliocene and recent--relations of the post-pliocene deposits of the northern hemisphere to the "glacial period"--pre-glacial deposits--glacial deposits--arctic mollusca in glacial beds--post-glacial deposits--nature and mode of formation of high-level and low-level gravels--nature and mode of formation of cavern-deposits--kent's cavern-post--pliocene deposits of the southern hemisphere. chapter xxii. life of the post-pliocene period--effect of the coming on and departure of the glacial period upon the animals inhabiting the northern hemisphere--birds of the post-pliocene--mammalia of the post-pliocene--climate of the post-glacial period as deduced from the post-glacial mammals--occurrence of the bones and implements of man in post-pliocene deposits in association with the remains of extinct mammalia--literature relating to the post-pliocene period. chapter xxiii. the succession of life upon the globe--gradual and successive introduction of life-forms--what is meant by "lower" and "higher" groups of animals and plants--succession in time of the great groups of animals in the main corresponding with their zoological order--identical phenomena in the vegetable kingdom--persistent types of life--high organisation of many early forms--bearings of palæontology on the general doctrine of evolution. appendix.--tabular view of the chief divisions of the animal kingdom. glossary. index. list of illustrations fig. . cast of _trigonia longa_. . microscopic section of the wood of a fossil conifer. . microscopic section of the wood of the larch. . section of carboniferous strata, kinghorn, fife. . diagram illustrating the formation of stratified deposits. . microscopic section of a calcareous breccia. . microscopic section of white chalk. . organisms in atlantic ooze. . crinoidal marble. . piece of nummulitic limestone, pyramids. . microscopic section of foraminiferal limestone--carboniferous, america. . microscopic section of lower silurian limestone. . microscopic section of oolitic limestone, jurassic. . microscopic section of oolitic limestone, carboniferous. . organisms in barbadoes earth. . organisms in richmond earth. . ideal section of the crust of the earth. . unconformable junction of chalk and eocene rocks. . erect trunk of a _sigillaria_. . diagrammatic section of the laurentian rocks. . microscopic section of laurentian limestone. . fragment of a mass of _eozoön canadense_. . diagram illustrating the structure of _eozoön_. . microscopic section of _eozoön canadense_. . _nonionina_ and _gromia_. . group of shells of living _foraminifera_. . diagrammatic section of cambrian strata. . _eophyton linneanum_. . _oldhamia antiqua_. . _scolithus canadensis_. . group of cambrian trilobites. . group of characteristic cambrian fossils. . fragment of _dictyonema sociale_. . generalised section of the lower silurian rocks of wales. . generalised section of the lower silurian rocks of north america. . _licrophycus ottawaensis_. . _astylospongia proemorsa_. . _stromatopora rugosa_. . _dichograptus octobrachiatus_. . _didymograptus divaricatus_. . _diplograptus pristis_. . _phyllograptus typus_. . _zaphrentis stokesi_. . _strombodes pentagonus_. . _columnaria alveolata_. . group of cystideans. . group of lower silurian crustaceans. . _ptilodictya falciformis_. . _ptilodictya schafferi_. . group of lower silurian brachiopods. . group of lower silurian brachiopods. . _murchisonia gracilis_. . _bellerophon argo_. . _maclurea crenulata_. . _orthoceras crebriseptum_. . restoration of _orthoceras_. . generalised section of the upper silurian rocks. . _monograptus priodon_. . _halysites catenularia_ and _h. agglomerata_. . group of upper silurian star-fishes. . _protaster sedgwickii_. . group of upper silurian crinoids. . _planolites vulgaris_. . group of upper silurian trilobites. . _pterygotus anglicus_. . group of upper silurian _polyzoa_. . _spirifera hysterica_. . group of upper silurian brachiopods. . group of upper silurian brachiopods. . _pentamerus knightii_. . _cardiola interrupta, c. fibrosa_, and _pterinoea subfalcata_. . group of upper silurian univalves. . _tentaculites ornatus_. . _pteraspis banksii_. . _onchus tenuistriatus_ and _thelodus_. . generalised section of the devonian rocks of north america. . _psilophyton princeps_. . _prototaxites logani_. . _stromatopora tuberculata_. . _cystiphyllum vesiculosum_. . _zaphrentis cornicula_. . _heliophyllum exiguum_. . _crepidophyllum archiaci_. . _favosites gothlandica_. . _favosites hemisphoerica_. . _spirorbis omphalodes_ and _s. arkonensis_. . _spirorbis laxus_ and _s. spinulifera_. . group of devonian trilobites. . wing of _platephemera antiqua_. . _clathropora intertexta_. . _ceriopora hamiltonensis_. . _fenestella magnifica_. . _retepora phillipsi_. . _fenestella cribrosa_. . _spirifera sculptilis_. . _spirifera mucronata_. . _atrypa reticularis_. . _strophomena rhomboidalis_. . _platyceras dumosum_. . _conularia ornata_. . _clymenia sedgwickii_. . group of fishes from the devonian rocks of north america. . _cephalaspis lyellii_. . _pterichthys cornutus_. . _polypterus_ and _osteolepis_. . _holoptychius nobilissimus_. . generalised section of the carboniferous rocks of the north of england. . _odontopteris schlotheimii_. . _calamites cannoeformis_. . _lepidodendron sternbergii_. . _sigillaria groeseri_. . _stigmaria ficoides_. . _trigonocarpum ovatum_. . microscopic section of foraminiferal limestone--carboniferous, north america. . _fusulina cylindrica_. . group of carboniferous corals. . _platycrinus tricontadactylus_. . _pentremites pyriformis_ and _p. conoideus_. . _archoeocidaris ellipticus_. . _spirorbis carbonarius_. . _prestwichia rotundata_. . group of carboniferous crustaceans. . _cyclophthalmus senior_. . _xylobius sigillarioe_. . _haplophlebium barnesi_. . group of carboniferous _polyzoa_. . group of carboniferous _brachiopoda_. . _pupa vetusta_. . _goniatites fossoe_. . _amblypterus macropterus_. . _cochliodus contortus_. . _anthracosaurus russelli_. . generalised section of the permian rocks. . _walchia piniformis_. . group of permian _brachiopods_. . _arca antiqua_. . _platysomus gibbosus_. . _protorosaurus speneri_. . generalised section of the triassic rocks. . _zamia spiralis_. . triassic conifers and cycads. . _encrinus liliiformis_. . _aspidura loricata_. . group of triassic bivalves. . _ceratites nodosus_. . tooth of _ceratodus serratus_ and _c. altus_. . _ceratodus fosteri_. . footprints of _cheirotherium_. . section of tooth of _labyrinthodont_. . skull of _mastodonsaurus_. . skull of _rhynchosaurus_. . _belodon_, _nothosaurus_, _paloeosaurus_, &c. . _placodus gigas_. . skulls of _dicynodon_ and _oudenodon_. . supposed footprint of bird, from the trias of connecticut. . lower jaw of _dromatherium sylvestre_. . molar tooth of _microlestes antiquus_. . _myrmecobius fasciatus_. . generalised section of the jurassic rocks. . _mantellia megalophylla_. . _thecosmilia annularis_. . _pentacrinus fasciculosus_. . _hemicidaris crenularis_. . _eryon arctiformis_. . group of jurassic brachiopods. . _ostrea marshii_. . _gryphoea incurva_ . _diceras arietina_. . _nerinoea goodhallii_. . _ammonites humphresianus_. . _ammonites bifrons_. . _beloteuthis subcostata_. . belemnite restored; diagram of belemnite; _belemnites canaliculata_. . _tetragonolepis_. . _acrodus nobilis_. . _ichthyosaurus communis_. . _plesiosaurus dolichodeirus_. . _pterodactylus crassirostris_. . _ramphorhynchus bucklandi_, restored. . skull of _megalosaurus_. . _archoeopteryx macrura_. . _archoeopteryx, restored_. . jaw of _amphitherium prevostii_. . jaws of oolitic mammals. . generalised section of the cretaceous rocks. . cretaceous angiosperms. . _rotalia boueana_. . _siphonia ficus_. . _ventriculites simplex_. . _synhelia sharpeana_. . _galerites albogalerus_. . _discoidea cylindrica_. . _escharina oceani_. . _terebratella astieriana_. . _crania ignabergensis_. . _ostrea couloni_. . _spondylus spinosus_. . _inoceramus sulcatus_. . _hippurites toucasiana_. . _voluta elongata_. . _nautilus danicus_. . _ancyloceras matheronianus_. . _turrilites catenatus_ . forms of cretaceous _ammonitidoe_. . _belemnitella mucronata_. . tooth of _hybodus_. . fin-spine of _hybodus_. . _beryx lewesiensis_ and _osmeroides mantelli_. . teeth of _iguanodon_. . skull of _mosasaurus camperi_. . _chelone benstedi_. . jaws and vertebræ of _odontornithes_. . fruit of _nipadites_. . _nummulina loevigata_. . _turbinolia sulcata_. . _cardita planicosta_. . _typhis tubifer_. . _cyproea elegans_. . _cerithium hexagonum_. . _limnoea pyramidalis_. . _physa columnaris_. . _cyclostoma arnoudii_. . _rhombus minimus_. . _otodus obliquus_. . _myliobatis edwardsii_. . upper jaw of alligator. . skull of _odontopteryx toliapicus_. . _zeuglodon cetoides_. . _paloeotherium magnum_, restored. . feet of _equidoe_. . _anoplothelium commune_. . skull of _dinoceras mirabilis_. . _vespertilio parisiensis_. . miocene palms. . _platanus aceroides_. . _cinnamomum polymorphum_. . _textularia meyeriana_. . _scutella subrotunda_. . _hyalea orbignyana_. . tooth of _oxyrhina_. . tooth of _carcharodon_. . _andrias scheuchzeri_. . skull of _brontotherium ingens_. , _hippopotamus sivalensis_. . skull of _sivatherium_. . skull of _deinotherium_. . tooth of _elephas planfrons_ and of _mastodon sivalensis_. . jaw of _pliopithecus_. . _rhinoceros etruscus_ and _r. megarhinus_. . molar tooth of _mastodon arvernensis_. . molar tooth of _etephas meridionalis_. . molar tooth of _elephas antiquus_. . skull and tooth of _machairodus cultridens_. . _pecten islandicus_. . diagram of high-level and low-level gravels. . diagrammatic section of cave. . _dinornis elephantopus_. . skull of _diprotodon_. . skull of _thylacoleo_. . skeleton of _megatherium_. . skeleton of _mylodon_. . _glyptodon clavipes_. . skull of _rhinoceros tichorhinus_. . skeleton of _cervus megaceros_. . skull of _bos primigenius_. . skeleton of mammoth. . molar tooth of mammoth. . skull of _ursus speloeus_. . skull of _hyoena speloea_. . lower jaw of _trogontherium cuvieri_. part i. principles of palÆontology. introduction. the laws of geological action. under the general title of "geology" are usually included at least two distinct branches of inquiry, allied to one another in the closest manner, and yet so distinct as to be largely capable of separate study. _geology_,[ ] in its strict sense, is the science which is concerned with the investigation of the materials which compose the earth, the methods in which those materials have been arranged, and the causes and modes of origin of these arrangements. in this limited aspect, geology is nothing more than the physical geography of the past, just as physical geography is the geology of to-day; and though it has to call in the aid of physics, astronomy, mineralogy, chemistry, and other allies more remote, it is in itself a perfectly distinct and individual study. one has, however, only to cross the threshold of geology to discover that the field and scope of the science cannot be thus rigidly limited to purely physical problems. the study of the physical development of the earth throughout past ages brings us at once in contact with the forms of animal and vegetable life which peopled its surface in bygone epochs, and it is found impossible adequately to comprehend the former, unless we possess some knowledge of the latter. however great its physical advances may be, geology remains imperfect till it is wedded with palæontology,[ ] a study which essentially belongs to the vast complex of the biological sciences, but at the same time has its strictly geological side. dealing, as it does, wholly with the consideration of such living beings as do not belong exclusively to the present order of things, palæontology is, in reality, a branch of natural history, and may be regarded as substantially the zoology and botany of the past. it is the ancient life-history of the earth, as revealed to us by the labours of palæontologists, with which we have mainly to do here; but before entering upon this, there are some general questions, affecting geology and palæontology alike, which may be very briefly discussed. [footnote : gr. _ge_, the earth; _logos_, a discourse.] [footnote : gr. _palaios_, ancient; _onta_, beings; _logos_, discourse.] the working geologist, dealing in the main with purely physical problems, has for his object to determine the material structure of the earth, and to investigate, as far as may be, the long chain of causes of which that structure is the ultimate result. no wider or more extended field of inquiry could be found; but philosophical geology is not content with this. at all the confines of his science, the transcendental geologist finds himself confronted with some of the most stupendous problems which have ever engaged the restless intellect of humanity. the origin and primæval constitution of the terrestrial globe, the laws of geologic action through long ages of vicissitude and development, the origin of life, the nature and source of the myriad complexities of living beings, the advent of man, possibly even the future history of the earth, are amongst the questions with which the geologist has to grapple in his higher capacity. these are problems which have occupied the attention of philosophers in every age of the world, and in periods long antecedent to the existence of a science of geology. the mere existence of cosmogonies in the religion of almost every nation, both ancient and modern, is a sufficient proof of the eager desire of the human mind to know something of the origin of the earth on which we tread. every human being who has gazed on the vast panorama of the universe, though it may have been but with the eyes of a child, has felt the longing to solve, however imperfectly, "the riddle of the painful earth," and has, consciously or unconsciously, elaborated some sort of a theory as to the why and wherefore of what he sees. apart from the profound and perhaps inscrutable problems which lie at the bottom of human existence, men have in all ages invented theories to explain the common phenomena of the material universe; and most of these theories, however varied in their details, turn out on examination to have a common root, and to be based on the same elements. modern geology has its own theories on the same subject, and it will be well to glance for a moment at the principles underlying the old and the new views. it has been maintained, as a metaphysical hypothesis, that there exists in the mind of man an inherent principle, in virtue of which he believes and expects that what has been, will be; and that the course of nature will be a continuous and uninterrupted one. so far, however, from any such belief existing as a necessary consequence of the constitution of the human mind, the real fact seems to be that the contrary belief has been almost universally prevalent. in all old religions, and in the philosophical systems of almost all ancient nations, the order of the universe has been regarded as distinctly unstable, mutable, and temporary. a beginning and an end have always been assumed, and the course of terrestrial events between these two indefinite points has been regarded as liable to constant interruption by revolutions and catastrophes of different kinds, in many cases emanating from supernatural sources. few of the more ancient theological creeds, and still fewer of the ancient philosophies, attained body and shape without containing, in some form or another, the belief in the existence of periodical convulsions, and of alternating cycles of destruction and repair. that geology, in its early infancy, should have become imbued with the spirit of this belief, is no more than might have been expected; and hence arose the at one time powerful and generally-accepted doctrine of "catastrophism." that the succession of phenomena upon the globe, whereby the earth's crust had assumed the configuration and composition which we find it to possess, had been a discontinuous and broken succession, was the almost inevitable conclusion of the older geologists. everywhere in their study of the rocks they met with apparently impassable gaps, and breaches of continuity that could not be bridged over. everywhere they found themselves conducted abruptly from one system of deposits to others totally different in mineral character or in stratigraphical position. everywhere they discovered that well-marked and easily recognisable groups of animals and plants were succeeded, without the intermediation of any obvious lapse of time, by other assemblages of organic beings of a different character. everywhere they found evidence that the earth's crust had undergone changes of such magnitude as to render it seemingly irrational to suppose that they could have been produced by any process now in existence. if we add to the above the prevalent belief of the time as to the comparative brevity of the period which had elapsed since the birth of the globe, we can readily understand the general acceptance of some form of catastrophism amongst the earlier geologists. as regards its general sense and substance, the doctrine of catastrophism held that the history of the earth, since first it emerged from the primitive chaos, had been one of periods of repose, alternating with catastrophes and cataclysms of a more or less violent character. the periods of tranquillity were supposed to have been long and protracted; and during each of them it was thought that one of the great geological "formations" was deposited. in each of these periods, therefore, the condition of the earth was supposed to be much the same as it is now--sediment was quietly accumulated at the bottom of the sea, and animals and plants flourished uninterruptedly in successive generations. each period of tranquillity, however, was believed to have been, sooner or later, put an end to by a sudden and awful convulsion of nature, ushering in a brief and paroxysmal period, in which the great physical forces were unchained and permitted to spring into a portentous activity. the forces of subterranean fire, with their concomitant phenomena of earthquake and volcano, were chiefly relied upon as the efficient causes of these periods of spasm and revolution. enormous elevations of portions of the earth's crust were thus believed to be produced, accompanied by corresponding and equally gigantic depressions of other portions. in this way new ranges of mountains were produced, and previously existing ranges levelled with the ground, seas were converted into dry land, and continents buried beneath the ocean--catastrophe following catastrophe, till the earth was rendered uninhabitable, and its races of animals and plants were extinguished, never to reappear in the same form. finally, it was believed that this feverish activity ultimately died out, and that the ancient peace once more came to reign upon the earth. as the abnormal throes and convulsions began to be relieved, the dry land and sea once more resumed their relations of stability, the conditions of life were once more established, and new races of animals and plants sprang into existence, to last until the supervention of another fever-fit. such is the past history of the globe, as sketched for us, in alternating scenes of fruitful peace and revolutionary destruction, by the earlier geologists. as before said, we cannot wonder at the former general acceptance of catastrophistic doctrines. even in the light of our present widely-increased knowledge, the series of geological monuments remains a broken and imperfect one; nor can we ever hope to fill up completely the numerous gaps with which the geological record is defaced. catastrophism was the natural method of accounting for these gaps, and, as we shall see, it possesses a basis of truth. at present, however, catastrophism may be said to be nearly extinct, and its place is taken by the modern doctrine of "continuity" or "uniformity"--a doctrine with which the name of lyell must ever remain imperishably associated. the fundamental thesis of the doctrine of uniformity is, that, in spite of all apparent violations of continuity, the sequence of geological phenomena has in reality been a regular and uninterrupted one; and that the vast changes which can be shown to have passed over the earth in former periods have been the result of the slow and ceaseless working of the ordinary physical forces--acting with no greater intensity than they do now, but acting through enormously prolonged periods. the essential element in the theory of continuity is to be found in the allotment of indefinite time for the accomplishment of the known series of geological changes. it is obviously the case, namely, that there are two possible explanations of all phenomena which lie so far concealed in "the dark backward and abysm of time," that we can have no direct knowledge of the manner in which they were produced. we may, on the one hand, suppose them to be the result of some very powerful cause, acting through a short period of time. that is catastrophism. or, we may suppose them to be caused by a much weaker force operating through a proportionately prolonged period. this is the view of the uniformitarians. it is a question of _energy_ versus _time_ and it is _time_ which is the true element of the case. an earthquake may remove a mountain in the course of a few seconds; but the dropping of the gentle rain will do the same, if we extend its operations over a millennium. and this is true of all agencies which are now at work, or ever have been at work, upon our planet. the catastrophists, believing that the globe is but, as it were, the birth of yesterday, were driven of necessity to the conclusion that its history had been checkered by the intermittent action of paroxysmal and almost inconceivably potent forces. the uniformitarians, on the other hand, maintaining the "adequacy of existing causes," and denying that the known physical forces ever acted in past time with greater intensity than they do at present, are, equally of necessity, driven to the conclusion that the world is truly in its "hoary eld," and that its present state is really the result of the tranquil and regulated action of known forces through unnumbered and innumerable centuries. the most important point for us, in the present connection, is the bearing of these opposing doctrines upon the question, as to the origin of the existing terrestrial order. on any doctrine of uniformity that order has been evolved slowly, and, according to law, from a pre-existing order. any doctrine of catastrophism, on the other hand, carries with it, by implication, the belief that the present order of things was brought about suddenly and irrespective of any pre-existent order; and it is important to hold clear ideas as to which of these beliefs is the true one. in the first place, we may postulate that the world had a beginning, and, equally, that the existing terrestrial order had a beginning. however far back we may go, geology does not, and cannot, reach the actual beginning of the world; and we are, therefore, left simply to our own speculations on this point. with regard, however, to the existing terrestrial order, a great deal can be discovered, and to do so is one of the principal tasks of geological science. the first steps in the production of that order lie buried in the profound and unsearchable depths of a past so prolonged as to present itself to our finite minds as almost in eternity. the last steps are in the prophetic future, and can be but dimly guessed at. between the remote past and the distant future, we have, however, a long period which is fairly open to inspection; and in saying a "long" period, it is to be borne in mind that this term is used in its _geological_ sense. within this period, enormously long as it is when measured by human standards, we can trace with reasonable certainty the progressive march of events, and can determine the laws of geological action, by which the present order of things has been brought about. the natural belief on this subject doubtless is, that the world, such as we now see it, possessed its present form and configuration from the beginning. nothing can be more natural than the belief that the present continents and oceans have always been where they are now; that we have always had the same mountains and plains; that our rivers have always had their present courses, and our lakes their present positions; that our climate has always been the same; and that our animals and plants have always been identical with those now familiar to us. nothing could be more natural than such a belief, and nothing could be further removed from the actual truth. on the contrary, a very slight acquaintance with geology shows us, in the words of sir john herschel, that "the actual configuration of our continents and islands, the coast-lines of our maps, the direction and elevation of our mountain-chains, the courses of our rivers, and the soundings of our oceans, are not things primordially arranged in the construction of our globe, but results of successive and complex actions on a former state of things; _that_, again, of similar actions on another still more remote; and so on, till the original and really permanent state is pushed altogether out of sight and beyond the reach even of imagination; while on the other hand, a similar, and, as far as we can see, interminable vista is opened out for the future, by which the habitability of our planet is secured amid the total abolition on it of the present theatres of terrestrial life." geology, then, teaches us that the physical features which now distinguish the earth's surface have been produced as the ultimate result of an almost endless succession of precedent changes. palæontology teaches us, though not yet in such assured accents, the same lesson. our present animals and plants have not been produced, in their innumerable forms, each as we now know it, as the sudden, collective, and simultaneous birth of a renovated world. on the contrary, we have the clearest evidence that some of our existing animals and plants made their appearance upon the earth at a much earlier period than others. in the confederation of animated nature some races can boast of an immemorial antiquity, whilst others are comparative _parvenus_. we have also the clearest evidence that the animals and plants which now inhabit the globe have been preceded, over and over again, by other different assemblages of animals and plants, which have flourished in successive periods of the earth's history, have reached their culmination, and then have given way to a fresh series of living beings. we have, finally, the clearest evidence that these successive groups of animals and plants (faunæ and floræ) are to a greater or less extent directly connected with one another. each group is, to a greater or less extent, the lineal descendant of the group which immediately preceded it in point of time, and is more or less fully concerned with giving origin to the group which immediately follows it. that this law of "evolution" has prevailed to a great extent is quite certain; but it does not meet all the exigencies of the case, and it is probable that its action has been supplemented by some still unknown law of a different character. we shall have to consider the question of geological "continuity" again. in the meanwhile, it is sufficient to state that this doctrine is now almost universally accepted as the basis of all inquiries, both in the domain of geology and that of palæontology. the advocates of continuity possess one immense advantage over those who believe in violent and revolutionary convulsions, that they call into play only agencies of which we have actual knowledge. we _know_ that certain forces are now at work, producing certain modifications in the present condition of the globe; and we _know_ that these forces are capable of producing the vastest of the changes which geology brings under our consideration, provided we assign a time proportionately vast for their operation. on the other hand, the advocates of catastrophism, to make good their views, are compelled to invoke forces and actions, both destructive and restorative, of which we have, and can have, no direct knowledge. they endow the whirlwind and the earthquake, the central fire and the rain from heaven, with powers as mighty as ever imagined in fable, and they build up the fragments of a repeatedly shattered world by the intervention of an intermittently active creative power. it should not be forgotten, however, that from one point of view there is a truth in catastrophism which is sometimes overlooked by the advocates of continuity and uniformity. catastrophism has, as its essential feature, the proposition that the known and existing forces of the earth at one time acted with much greater intensity and violence than they do at present, and they carry down the period of this excessive action to the commencement of the present terrestrial order. the uniformitarians, in effect, deny this proposition, at any rate as regards any period of the earth's history of which we have actual cognisance. if, however, the "nebular hypothesis" of the origin of the universe be well founded--as is generally admitted--then, beyond question, the earth is a gradually cooling body, which has at one time been very much hotter than it is at present. there has been a time, therefore, in which the igneous forces of the earth, to which we owe the phenomena of earthquakes and volcanoes, must have been far more intensely active than we can conceive of from anything that we can see at the present day. by the same hypothesis, the sun is a cooling body, and must at one time have possessed a much higher temperature than it has at present. but increased heat of the sun would seriously alter the existing conditions affecting the evaporation and precipitation of moisture on our earth; and hence the aqueous forces may also have acted at one time more powerfully than they do now. the fundamental principle of catastrophism is, therefore, not wholly vicious; and we have reason to think that there must have been periods--very remote, it is true, and perhaps unrecorded in the history of the earth--in which the known physical forces may have acted with an intensity much greater than direct observation would lead us to imagine. and this may be believed, altogether irrespective of those great secular changes by which hot or cold epochs are produced, and which can hardly be called "catastrophistic," as they are produced gradually, and are liable to recur at definite intervals. admitting, then, that there _is_ a truth at the bottom of the once current doctrines of catastrophism, still it remains certain that the history of the earth has been one of _law_ in all past time, as it is now. nor need we shrink back affrighted at the vastness of the conception--the vaster for its very vagueness--that we are thus compelled to form as to the duration of _geological time_. as we grope our way backward through the dark labyrinth of the ages, epoch succeeds to epoch, and period to period, each looming more gigantic in its outlines and more shadowy in its features, as it rises, dimly revealed, from the mist and vapour of an older and ever-older past. it is useless to add century to century or millennium to millennium. when we pass a certain boundary-line, which, after all, is reached very soon, figures cease to convey to our finite faculties any real notion of the periods with which we have to deal. the astronomer can employ material illustrations to give form and substance to our conceptions of celestial space; but such a resource is unavailable to the geologist. the few thousand years of which we have historical evidence sink into absolute insignificance beside the unnumbered æons which unroll themselves one by one as we penetrate the dim recesses of the past, and decipher with feeble vision the ponderous volumes in which the record of the earth is written. vainly does the strained intellect seek to overtake an ever-receding commencement, and toil to gain some adequate grasp of an apparently endless succession. a beginning there must have been, though we can never hope to fix its point. even speculation droops her wings in the attenuated atmosphere of a past so remote, and the light of imagination is quenched in the darkness of a history so ancient. in _time_, as in _space_, the confines of the universe must ever remain concealed from us, and of the end we know no more than of the beginning. inconceivable as is to us the lapse of "geological time," it is no more than "a mere moment of the past, a mere infinitesimal portion of eternity." well may "the human heart, that weeps and trembles," say, with richter's pilgrim through celestial space, "i will go no farther; for the spirit of man acheth with this infinity. insufferable is the glory of god. let me lie down in the grave, and hide me from the persecution of the infinite, for end, i see, there is none." chapter i. the scope and materials of palÆontology. the study of the rock-masses which constitute the crust of the earth, if carried out in the methodical and scientific manner of the geologist, at once brings us, as has been before remarked, in contact with the remains or traces of living beings which formerly dwelt upon the globe. such remains are found, in greater or less abundance, in the great majority of rocks; and they are not only of great interest in themselves, but they have proved of the greatest importance as throwing light upon various difficult problems in geology, in natural history, in botany, and in philosophy. their study constitutes the science of palæontology; and though it is possible to proceed to a certain length in geology and zoology without much palæontological knowledge, it is hardly possible to attain to a satisfactory general acquaintance with either of these subjects without having mastered the leading facts of the first. similarly, it is not possible to study palæontology without some acquaintance with both geology and natural history. palæontology, then, is the science which treats of the living beings, whether animal or vegetable, which have inhabited the earth during past periods of its history. its object is to elucidate, as far as may be, the structure, mode of existence, and habits of all such ancient forms of life; to determine their position in the scale of organised beings; to lay down the geographical limits within which they flourished; and to fix the period of their advent and disappearance. it is the ancient life-history of the earth; and were its record complete, it would furnish us with a detailed knowledge of the form and relations of all the animals and plants which have at any period flourished upon the land-surfaces of the globe or inhabited its waters; it would enable us to determine precisely their succession in time; and it would place in our hands an unfailing key to the problems of evolution. unfortunately, from causes which will be subsequently discussed, the palæontological record is extremely imperfect, and our knowledge is interrupted by gaps, which not only bear a large proportion to our solid information, but which in many cases are of such a nature that we can never hope to fill them up. fossils.--the remains of animals or vegetables which we now find entombed in the solid rock, and which constitute the working material of the palæontologist, are termed "fossils,"[ ] or "petrifactions." in most cases, as can be readily understood, fossils are the actual hard parts of animals and plants which were in existence when the rock in which they are now found was being deposited. most fossils, therefore, are of the nature of the shells of shell-fish, the skeletons of coral-zoophytes, the bones of vertebrate animals, or the wood, bark, or leaves of plants. all such bodies are more or less of a hard consistence to begin with, and are capable of resisting decay for a longer or shorter time--hence the frequency with which they occur in the fossil condition. strictly speaking, however, by the term "fossil" must be understood "any body, _or the traces of the existence of any body_, whether animal or vegetable, which has been buried in the earth by natural causes" (lyell). we shall find, in fact, that many of the objects which we have to study as "fossils" have never themselves actually formed parts of any animal or vegetable, though they are due to the former existence of such organisms, and indicate what was the nature of these. thus the footprints left by birds, or reptiles, or quadrupeds upon sand or mud, are just as much proofs of the former existence of these animals as would be bones, feathers, or scales, though in themselves they are inorganic. under the head of fossils, therefore, come the footprints of air-breathing vertebrate animals; the tracks, trails, and burrows of sea-worms, crustaceans, or molluscs; the impressions left on the sand by stranded jelly-fishes; the burrows in stone or wood of certain shell-fish; the "moulds" or "casts" of shells, corals, and other organic remains; and various other bodies of a more or less similar nature. [footnote : lat. _fossus_, dug up.] fossilisation.-- the term "fossilisation" is applied to all those processes through which the remains of organised beings may pass in being converted into fossils. these processes are numerous and varied; but there are three principal modes of fossilisation which alone need be considered here. in the first instance, the fossil is to all intents and purposes an actual portion of the original organised being--such as a bone, a shell, or a piece of wood. in some rare instances, as in the case of the body of the mammoth discovered embedded in ice at the mouth of the lena in siberia, the fossil may be preserved almost precisely in its original condition, and even with its soft parts uninjured. more commonly, certain changes have taken place in the fossil, the principal being the more or less total removal of the organic matter originally present. thus bones become light and porous by the removal of their gelatine, so as to cleave to the tongue on being applied to that organ; whilst shells become fragile, and lose their primitive colours. in other cases, though practically the real body it represents, all the cavities of the fossil, down to its minutest recesses, may have become infiltrated with mineral matter. it need hardly be added, that it is in the more modern rocks that we find the fossils, as a rule, least changed from their former condition; but the original structure is often more or less completely retained in some of the fossils from even the most ancient formations. in the second place, we very frequently meet with fossils in the state of "casts" or moulds of the original organic body. what occurs in this case will be readily understood if we imagine any common bivalve shell, as an oyster, or mussel, or cockle, embedded in clay or mud. if the clay were sufficiently soft and fluid, the first thing would be that it would gain access to the interior of the shell, and would completely fill up the space between the valves. the pressure, also, of the surrounding matter would insure that the clay would everywhere adhere closely to the exterior of the shell. if now we suppose the clay to be in any way hardened so as to be converted into stone, and if we were to break up the stone, we should obviously have the following state of parts. the clay which filled the shell would form an accurate cast of the _interior_ of the shell, and the clay outside would give us an exact impression or cast of the _exterior_ of the shell (fig. ). we should have, then, two casts, an interior and an exterior, and the two would be very different to one another, since the inside of a shell is very unlike the outside. in the case, in fact, of many univalve shells, the interior cast or "mould" is so unlike the exterior cast, or unlike the shell itself, that it may be difficult to determine the true origin of the former. [illustration: fig. .--_trigonia longa_, showing casts to of the exterior and interior of the shell.--cretaceous (neocomian).] it only remains to add that there is sometimes a further complication. if the rock be very porous and permeable by water, it may happen that the original shell is entirely dissolved away, leaving the interior cast loose, like the kernel of a nut, within the case formed by the exterior cast. or it may happen that subsequent to the attainment of this state of things, the space thus left vacant between the interior and exterior cast--the space, that is, formerly occupied by the shell itself--may be filled up by some foreign mineral deposited there by the infiltration of water. in this last case the splitting open of the rock would reveal an interior cast, an exterior cast, and finally a body which would have the exact form of the original shell, but which would be really a much later formation, and which would not exhibit under the microscope the minute structure of shell. [illustration: fig. .--microscopic section of the silicified wood of a conifer (_sequoia_) cut in the long direction of the fibres. post-tertiary? colorado. (original.)] [illustration: footnote: fig. .--microscopic section of the wood of the common larch (_abies larix_), cut in the long direction of the fibres. in both the fresh and the fossil wood (fig. ) are seen the discs characteristic of coniferous wood. (original.)] in the third class of cases we have fossils which present with the greatest accuracy the external form, and even sometimes the internal minute structure, of the original organic body, but which, nevertheless, are not themselves truly organic, but have been formed by a "replacement" of the particles of the primitive organism by some mineral substance. the most elegant example of this is afforded by fossil wood which has been "silicified" or converted into flint (_silex_). in such cases we have fossil wood which presents the rings of growth and fibrous structure of recent wood, and which under the microscope exhibits the minutest vessels which characterise ligneous tissue, together with the even more minute markings of the vessels (fig. ). the whole, however, instead of being composed of the original carbonaceous matter of the wood, is now converted into flint. the only explanation that can be given of this by no means rare phenomenon, is that the wood must have undergone a slow process of decay in water charged with silica or flint in solution. as each successive particle of wood was removed by decay, its place was taken by a particle of flint deposited from the surrounding water, till ultimately the entire wood was silicified. the process, therefore, resembles what would take place if we were to pull down a house built of brick by successive bricks, replacing each brick as removed by a piece of stone of precisely the same size and form. the result of this would be that the house would retain its primitive size, shape, and outline, but it would finally have been converted from a house of brick into a house of stone. many other fossils besides wood--such as shells, corals, sponges, &c.--are often found silicified; and this may be regarded as the commonest form of fossilisation by replacement. in other cases, however, though the principle of the process is the same, the replacing substance may be iron pyrites, oxide of iron, sulphur, malachite, magnesite, talc, &c.; but it is rarely that the replacement with these minerals is so perfect as to preserve the more delicate details of internal structure. chapter ii. the fossiliferous rocks. fossils are found in rocks, though not universally or promiscuously; and it is therefore necessary that the palæontologist should possess some acquaintance with, at any rate, those rocks which yield organic remains, and which are therefore said to be "_fossiliferous_." in geological language, all the materials which enter into the composition of the solid crust of the earth, be their texture what it may--from the most impalpable mud to the hardest granite--are termed "rocks;" and for our present purpose we may divide these into two great groups. in the first division are the _igneous rocks_--such as the lavas and ashes of volcanoes--which are formed within the body of the earth itself, and which owe their structure and origin to the action of heat. the igneous rocks are formed primarily below the surface of the earth, which they only reach as the result of volcanic action; they are generally destitute of distinct "stratification," or arrangement in successive layers; and they do not contain fossils, except in the comparatively rare instances where volcanic ashes have enveloped animals or plants which were living in the sea or on the land in the immediate vicinity of the volcanic focus. the second great division of rocks is that of the _fossiliferous, aqueous_, or _sedimentary_ rocks. these are formed at the surface of the earth, and, as implied by one of their names, are invariably deposited in water. they are produced by vital or chemical action, or are formed from the "sediment" produced by the disintegration and reconstruction of previously existing rocks, without previous solution; they mostly contain fossils; and they are arranged in distinct layers or "strata." the so-called "aerial" rocks which, like beds of blown sand, have been formed by the action of the atmosphere, may also contain fossils; but they are not of such importance as to require special notice here. for all practical purposes, we may consider that the aqueous rocks are the natural cemetery of the animals and plants of bygone ages; and it is therefore essential that the palæontological student should be acquainted with some of the principal facts as to their physical characters, their minute structure and mode of origin, their chief varieties, and their historical succession. the sedimentary or fossiliferous rocks form the greater portion of that part of the earth's crust which is open to our examination, and are distinguished by the fact that they are regularly "stratified" or arranged in distinct and definite layers or "strata." these layers may consist of a single material, as in a block of sandstone, or they may consist of different materials. when examined on a large scale, they are always found to consist of alternations of layers of different mineral composition. we may examine any given area, and find in it nothing but one kind of rock--sandstone, perhaps, or limestone. in all cases, however, if we extend our examination sufficiently far, we shall ultimately come upon different rocks; and, as a general rule, the thickness of any particular set of beds is comparatively small, so that different kinds of rock alternate with one another in comparatively small spaces. [illustration: fig. .--sketch of carboniferous strata at kinghorn, in fife, showing stratified beds (limestone and shales) surmounted by an unstratified mass of trap. (original.)] as regards the origin of the sedimentary rocks, they are for the most part "derivative" rocks, being derived from the wear and tear of pre-existent rocks. sometimes, however, they owe their origin to chemical or vital action, when they would more properly be spoken of simply as aqueous rocks. as to their mode of deposition, we are enabled to infer that the materials which compose them have formerly been spread out by the action of water, from what we see going on every day at the mouths of our great rivers, and on a smaller scale wherever there is running water. every stream, where it runs into a lake or into the sea, carries with it a burden of mud, sand, and rounded pebbles, derived from the waste of the rocks which form its bed and banks. when these materials cease to be impelled by the force of the moving water, they sink to the bottom, the heaviest pebbles, of course, sinking first, the smaller pebbles and sand next, and the finest mud last. ultimately, therefore, as might have been inferred upon theoretical grounds, and as is proved by practical experience, every lake becomes a receptacle for a series of stratified rocks produced by the streams flowing into it. these deposits may vary in different parts of the lake, according as one stream brought down one kind of material and another stream contributed another material; but in all cases the materials will bear ample evidence that they were produced, sorted, and deposited by running water. the finer beds of clay or sand will all be arranged in thicker or thinner layers or laminæ; and if there are any beds of pebbles these will all be rounded or smooth, just like the water-worn pebbles of any brook-course. in all probability, also, we should find in some of the beds the remains of fresh-water shells or plants or other organisms which inhabited the lake at the time these beds were being deposited. in the same way large rivers--such as the ganges or mississippi--deposit all the materials which they bring down at their mouths, forming in this way their "deltas." whenever such a delta is cut through, either by man or by some channel of the river altering its course, we find that it is composed of a succession of horizontal layers or strata of sand or mud, varying in mineral composition, in structure, or in grain, according to the nature of the materials brought down by the river at different periods. such deltas, also, will contain the remains of animals which inhabit the river, with fragments of the plants which grew on its banks, or bones of the animals which lived in its basin. nor is this action confined, of course, to large rivers only, though naturally most conspicuous in the greatest bodies of water. on the contrary, all streams, of whatever size, are engaged in the work of wearing down the dry land, and of transporting the materials thus derived from higher to lower levels, never resting in this work till they reach the sea. [illustration: fig. .--diagram to illustrate the formation of sedimentary deposits at the point where a river debouches into the sea.] lastly, the sea itself--irrespective of the materials delivered into it by rivers--is constantly preparing fresh stratified deposits by its own action. upon every coast-line the sea is constantly eating back into the land and reducing its component rocks to form the shingle and sand which we see upon every shore. the materials thus produced are not, however, lost, but are ultimately deposited elsewhere in the form of new stratified accumulations, in which are buried the remains of animals inhabiting the sea at the time. whenever, then, we find anywhere in the interior of the land any series of beds having these characters--composed, that is, of distinct layers, the particles of which, both large and small, show distinct traces of the wearing action of water--whenever and wherever we find such rocks, we are justified in assuming that they have been deposited by water in the manner above mentioned. either they were laid down in some former lake by the combined action of the streams which flowed into it; or they were deposited at the mouth of some ancient river, forming its delta; or they were laid down at the bottom of the ocean. in the first two cases, any fossils which the beds might contain would be the remains of fresh-water or terrestrial organisms. in the last case, the majority, at any rate, of the fossils would be the remains of marine animals. the term "formation" is employed by geologists to express "any group of rocks which have some character in common, whether of origin, age, or composition" (lyell); so that we may speak of stratified and unstratified formations, aqueous or igneous formations, fresh-water or marine formations, and so on. chief divisions of the aqueous rocks. the aqueous rocks may be divided into two great sections, the mechanically-formed and the chemically-formed, including under the last head all rocks which owe their origin to vital action, as well as those produced by ordinary chemical agencies. [illustration: fig. .--microscopic section of a calcareous breccia in the lower silurian (coniston limestone) of shap wells, westmoreland. the fragments are all of small size, and consist of angular pieces of transparent quartz, volcanic ashes, and limestone embedded in a matrix of crystalline limestone. (original.)] a. mechanically-formed rocks.--these are all those aqueous rocks of which we can obtain proofs that their particles have been mechanically transported to their present situation. thus, if we examine a piece of _conglomerate_ or puddingstone, we find it to be composed of a number of rounded pebbles embedded in an enveloping matrix or paste, which is usually of a sandy nature, but may be composed of carbonate of lime (when the rock is said to be a "calcareous conglomerate"). the pebbles in all conglomerates are worn and rounded by the action of water in motion, and thus show that they have been subjected to much mechanical attrition, whilst they have been mechanically transported for a greater or less distance from the rock of which they originally formed part. the analogue of the old conglomerates at the present day is to be found in the great beds of shingle and gravel which are formed by the action of the sea on every coast-line, and which are composed of water-worn and well-rounded pebbles of different sizes. a _breccia_ is a mechanically-formed rock, very similar to a conglomerate, and consisting of larger or smaller fragments of rock embedded in a common matrix. the fragments, however, are in this case all more or less angular, and are not worn or rounded. the fragments in breccias may be of large size, or they may be comparatively small (fig. ); and the matrix may be composed of sand (arenaceous) or of carbonate of lime (calcareous). in the case of an ordinary sandstone, again, we have a rock which may be regarded as simply a very fine-grained conglomerate or breccia, being composed of small grains of sand (silica), sometimes rounded, sometimes more or less angular, cemented together by some such substance as oxide of iron, silicate of iron, or carbonate of lime. a sandstone, therefore, like a conglomerate is a mechanically-formed rock, its component grams being equally the result of mechanical attrition and having equally been transported from a distance; and the same is true of the ordinary sand of the sea-shore, which is nothing more than an unconsolidated sandstone. other so-called sands and sandstones, though equally mechanical in their origin, are truly calcareous in their nature, and are more or less entirely composed of carbonate of lime. of this kind are the shell-sand so common on our coasts, and the coral-sand which is so largely formed in the neighbourhood of coral-reefs. in these cases the rock is composed of fragments of the skeletons of shellfish, and numerous other marine animals, together, in many instances, with the remains of certain sea-weeds (_corallines_, _nullipores_, &c,) which are endowed with the power of secreting carbonate of lime from the sea-water. lastly, in certain rocks still finer in their texture than sandstones, such as the various mud-rocks and shales, we can still recognise a mechanical source and origin. if slices of any of these rocks sufficiently thin to be transparent are examined under the microscope, it will be found that they are composed of minute grains of different sizes, which are all more or less worn and rounded, and which clearly show, therefore, that they have been subjected to mechanical attrition. all the above-mentioned rocks, then, are _mechanically-formed_ rocks; and they are often spoken of as "derivative rocks," in consequence of the fact that their particles can be shown to have been mechanically _derived_ from other pre-existent rocks. it follows from this that every bed of any mechanically-formed rock is the measure and equivalent of a corresponding amount of destruction of some older rock. it is not necessary to enter here into a minute account of the subdivisions of these rocks, but it may be mentioned that they may be divided into two principal groups, according to their chemical composition. in the one group we have the so-called _arenaceous_ (lat. _arena_, sand) or _siliceous_ rocks, which are essentially composed of larger or smaller grains of flint or silica. in this group are comprised ordinary sand, the varieties of sandstone and grit, and most conglomerates and breccias. we shall, however, afterwards see that some siliceous rocks are of organic origin. in the second group are the so-called _argillaceous_ (lat. _argilla_, clay) rocks, which contain a larger or smaller amount of clay or hydrated silicate of alumina in their composition. under this head come clays, shales, marls, marl-slate, clay-slates, and most flags and flagstones. b. chemically-formed rocks.--in this section are comprised all those aqueous or sedimentary rocks which have been formed by chemical agencies. as many of these chemical agencies, however, are exerted through the medium of living beings, whether animals or plants, we get into this section a number of what may be called "_organically-formed rocks_." these are of the greatest possible importance to the palæontologist, as being to a greater or less extent composed of the actual remains of animals or vegetables, and it will therefore be necessary to consider their character and structure in some detail. by far the most important of the chemically-formed rocks are the so-called _calcareous rocks_ (lat. _calx_, lime), comprising all those which contain a large proportion of carbonate of lime, or are wholly composed of this substance. carbonate of lime is soluble in water holding a certain amount of carbonic acid gas in solution; and it is, therefore, found in larger or smaller quantity dissolved in all natural waters, both fresh and salt, since these waters are always to some extent charged with the above-mentioned solvent gas. a great number of aquatic animals, however, together with some aquatic plants, are endowed with the power of separating the lime thus held in solution in the water, and of reducing it again to its solid condition. in this way shell-fish, crustaceans, sea-urchins, corals, and an immense number of other animals, are enabled to construct their skeletons; whilst some plants form hard structures within their tissues in a precisely similar manner. we do meet with some calcareous deposits, such as the "stalactites" and "stalagmites" of caves, the "calcareous tufa" and "travertine" of some hot springs, and the spongy calcareous deposits of so-called "petrifying springs," which are purely chemical in their origin, and owe nothing to the operation of living beings. such deposits are formed simply by the precipitation of carbonate of lime from water, in consequence of the evaporation from the water of the carbonic acid gas which formerly held the lime in solution; but, though sometimes forming masses of considerable thickness and of geological importance, they do not concern us here. almost all the limestones which occur in the series of the stratified rocks are, primarily at any rate, of _organic_ origin, and have been, directly or indirectly, produced by the action of certain lime-making animals or plants, or both combined. the presumption as to all the calcareous rocks, which cannot be clearly shown to have been otherwise produced, is that they are thus organically formed; and in many cases this presumption can be readily reduced to a certainty. there are many varieties of the calcareous rocks, but the following are those which are of the greatest importance:-- _chalk_ is a calcareous rock of a generally soft and pulverulent texture, and with an earthy fracture. it varies in its purity, being sometimes almost wholly composed of carbonate of lime, and at other times more or less intermixed with foreign matter. though usually soft and readily reducible to powder, chalk is occasionally, as in the north of ireland, tolerably hard and compact; but it never assumes the crystalline aspect and stony density of limestone, except it be in immediate contact with some mass of igneous rock. by means of the microscope, the true nature and mode of formation of chalk can be determined with the greatest ease. in the case of the harder varieties, the examination can be conducted by means of slices ground down to a thinness sufficient to render them transparent; but in the softer kinds the rock must be disintegrated under water, and the _débris_ examined microscopically. when investigated by either of these methods, chalk is found to be a genuine organic rock, being composed of the shells or hard parts of innumerable marine animals of different kinds, some entire, some fragmentary, cemented together by a matrix of very finely granular carbonate of lime. foremost amongst the animal remains which so largely compose chalk are the shells of the minute creatures which will be subsequently spoken of under the name of _foraminifera_ (fig. ), and which, in spite of their microscopic dimensions, play a more important part in the process of lime-making than perhaps any other of the larger inhabitants of the ocean. [illustration: fig. .--section of gravesend chalk, examined by transmitted light and highly magnified. besides the entire shells of _globigerina_, _rotalia_, and _textularia_, numerous detached chambers of _globigerina_ are seen. (original.)] as chalk is found in beds of hundreds of feet in thickness, and of great purity, there was long felt much difficulty in satisfactorily accounting for its mode of formation and origin. by the researches of carpenter, wyville thomson, huxley, wallich, and others, it has, however, been shown that there is now forming, in the profound depths of our great oceans, a deposit which is in all essential respects identical with chalk, and which is generally known as the "atlantic ooze," from its having been first discovered in that sea. this ooze is found at great depths ( to over , feet) in both the atlantic and pacific, covering enormously large areas of the sea-bottom, and it presents itself as a whitish-brown, sticky, impalpable mud, very like greyish chalk when dried. chemical examination shows that the ooze is composed almost wholly of carbonate of lime, and microscopical examination proves it to be of organic origin, and to be made up of the remains of living beings. the principal forms of these belong to the _foraminifera_, and the commonest of these are the irregularly-chambered shells of _globigerina_, absolutely indistinguishable from the _globigerinoe_ which are so largely present in the chalk (fig. ). along with these occur fragments of the skeletons of other larger creatures, and a certain proportion of the flinty cases of minute animal and vegetable organisms (_polycystina_ and _diatoms_). though many of the minute animals, the hard parts of which form the ooze, undoubtedly live at or near the surface of the sea, others, probably, really live near the bottom; and the ooze itself forms a congenial home for numerous sponges, sea-lilies, and other marine animals which flourish at great depths in the sea. there is thus established an intimate and most interesting parallelism between the chalk and the ooze of modern oceans. both are formed essentially in the same way, and the latter only requires consolidation to become actually converted into chalk. both are fundamentally organic deposits, apparently requiring a great depth of water for their accumulation, and mainly composed of the remains of _foraminifera_, together with the entire or broken skeletons of other marine animals of greater dimensions. it is to be remembered, however, that the ooze, though strictly representative of the chalk, cannot be said in any proper sense to be actually _identical_ with the formation so called by geologists. a great lapse of time separates the two, and though composed of the remains of representative classes or groups of animals, it is only in the case of the lowly-organised _globigerinoe_, and of some other organisms of little higher grade, that we find absolutely the same kinds or species of animals in both. [illustration: fig. .--organisms in the atlantic ooze, chiefly _foraminifera_ (_globigerina_ and _textularia_), with _polycystina_ and sponge-spicules; highly magnified. (original.)] [illustration: fig. .--slab of crinoidal marble, from the carboniferous limestone of dent, in yorkshire, of the natural size. the polished surface intersects the columns of the crinoids at different angles, and thus gives rise to varying appearances. (original.)] _limestone_, like chalk, is composed of carbonate of lime, sometimes almost pure, but more commonly with a greater or less intermixture of some foreign material, such as alumina or silica. the varieties of limestone are almost innumerable, but the great majority can be clearly proved to agree with chalk in being essentially of organic origin, and in being more or less largely composed of the remains of living beings. in many instances the organic remains which compose limestone are so large as to be readily visible to the naked eye, and the rock is at once seen to be nothing more than an agglomeration of the skeletons, generally fragmentary, of certain marine animals, cemented together by a matrix of carbonate of lime. this is the case, for example, with the so-called "crinoidal limestones" and "encrinital marbles" with which the geologist is so familiar, especially as occurring in great beds amongst the older formations of the earth's crust. these are seen, on weathered or broken surfaces, or still better in polished slabs (fig. ), to be composed more or less exclusively of the broken stems and detached plates of sea-lilies (_crinoids_). similarly, other limestones are composed almost entirely of the skeletons of corals; and such old coralline limestones can readily be paralleled by formations which we can find in actual course of production at the present day. we only need to transport ourselves to the islands of the pacific, to the west indies, or to the indian ocean, to find great masses of lime formed similarly by living corals, and well known to everyone under the name of "coral-reefs." such reefs are often of vast extent, both superficially and in vertical thickness, and they fully equal in this respect any of the coralline limestones of bygone ages. again, we find other limestones--such as the celebrated "nummulitic limestone" (fig. ), which sometimes attains a thickness of some thousands of feet--which are almost entirely made up of the shells of _foraminifera_. in the case of the "nummulitic limestone," just mentioned, these shells are of large size, varying from the size of a split pea up to that of a florin. there are, however, as we shall see, many other limestones, which are likewise largely made up of _foraminifera_, but in which the shells are very much more minute, and would hardly be seen at all without the microscope. [illustration: fig. .--piece of nummulitic limestone from the great pyramid. of the natural size. (original.)] we may, in fact, consider that the great agents in the production of limestones in past ages have been animals belonging to the _crinoids_, the _corals_, and the _foraminifera_. at the present day, the crinoids have been nearly extinguished, and the few known survivors seem to have retired to great depths in the ocean; but the two latter still actively carry on the work of lime-making, the former being very largely helped in their operations by certain lime-producing marine plants (_nullipores_ and _corallines_). we have to remember, however, that though the limestones, both ancient and modern, that we have just spoken of, are truly organic, they are not necessarily formed out of the remains of animals which actually lived on the precise spot where we now find the limestone itself. we may find a crinoidal limestone, which we can show to have been actually formed by the successive growth of generations of sea-lilies _in place_; but we shall find many others in which the rock is made up of innumerable fragments of the skeletons of these creatures, which have been clearly worn and rubbed by the sea-waves, and which have been mechanically transported to their present site. in the same way, a limestone may be shown to have been an actual coral-reef, by the fact that we find in it great masses of coral, growing in their natural position, and exhibiting plain proofs that they were simply quietly buried by the calcareous sediment as they grew; but other limestones may contain only numerous rolled and water-worn fragments of corals. this is precisely paralleled by what we can observe in our existing coral-reefs. parts of the modern coral-islands and coral-reefs are really made up of corals, dead or alive, which actually grew on the spot where we now find them; but other parts are composed of a limestone-rock ("coral-rock"), or of a loose sand ("coral-sand"), which is organic in the sense that it is composed of lime formed by living beings, but which, in truth, is composed of fragments of the skeletons of these living beings, mechanically transported and heaped together by the sea. to take another example nearer home, we may find great accumulations of calcareous matter formed _in place_, by the growth of shell-fish, such as oysters or mussels; but we can also find equally great accumulations on many of our shores in the form of "shell-sand," which is equally composed of the shells of molluscs, but which is formed by the trituration of these shells by the mechanical power of the sea-waves. we thus see that though all these limestones are primarily organic, they not uncommonly become "mechanically-formed" rocks in a secondary sense, the materials of which they are composed being formed by living beings, but having been mechanically transported to the place where we now find them. [illustration: fig. .--section of carboniferous limestone from spergen hill, indiana, u.s., showing numerous large-sized _foraminifera_ (_endothyra_) and a few oolitic grains; magnified. (original.)] [illustration: fig .--section of coniston limestone (lower silurian) from keisler, westmoreland; magnified. the matrix is very coarsely crystalline, and the included organic remains are chiefly stems of crinoids. (original.)] many limestones, as we have seen, are composed of large and conspicuous organic remains, such as strike the eye at once. many others, however, which at first sight appear compact, more or less crystalline, and nearly devoid of traces of life, are found, when properly examined, to be also composed of the remains of various organisms. all the commoner limestones, in fact, from the lower silurian period onwards, can be easily proved to be thus _organic_ rocks, if we investigate weathered or polished surfaces with a lens, or, still better, if we cut thin slices of the rock and grind these down till they are transparent. when thus examined, the rock is usually found to be composed of innumerable entire or fragmentary fossils, cemented together by a granular or crystalline matrix of carbonate of lime (figs. and ). when the matrix is granular, the rock is precisely similar to chalk, except that it is harder and less earthy in texture, whilst the fossils are only occasionally referable to the _foraminifera_. in other cases, the matrix is more or less crystalline, and when this crystallisation has been carried to a great extent, the original organic nature of the rock may be greatly or completely obscured thereby. thus, in limestones which have been greatly altered or "metamorphosed" by the combined action of heat and pressure, all traces of organic remains become annihilated, and the rock becomes completely crystalline throughout. this, for example, is the case with the ordinary white "statuary marble," slices of which exhibit under the microscope nothing but an aggregate of beautifully transparent crystals of carbonate of lime, without the smallest traces of fossils. there are also other cases, where the limestone is not necessarily highly crystalline, and where no metamorphic action in the strict sense has taken place, in which, nevertheless, the microscope fails to reveal any evidence that the rock is organic. such cases are somewhat obscure, and doubtless depend on different causes in different instances; but they do not affect the important generalisation that limestones are fundamentally the product of the operation of living beings. this fact remains certain; and when we consider the vast superficial extent occupied by calcareous deposits, and the enormous collective thickness of these, the mind cannot fail to be impressed with the immensity of the period demanded for the formation of these by the agency of such humble and often microscopic creatures as corals, sea-lilies, foraminifers, and shell-fish. amongst the numerous varieties of limestone, a few are of such interest as to deserve a brief notice. _magnesian limestone_ or _dolomite_, differs from ordinary limestone in containing a certain proportion of carbonate of magnesia along with the carbonate of lime. the typical dolomites contain a large proportion of carbonate of magnesia, and are highly crystalline. the ordinary magnesian limestones (such as those of durham in the permian series, and the guelph limestones of north america in the silurian series) are generally of a yellowish, buff, or brown colour, with a crystalline or pearly aspect, effervescing with acid much less freely than ordinary limestone, exhibiting numerous cavities from which fossils have been dissolved out, and often assuming the most varied and singular forms in consequence of what is called "concretionary action." examination with the microscope shows that these limestones are composed of an aggregate of minute but perfectly distinct crystals, but that minute organisms of different kinds, or fragments of larger fossils, are often present as well. other magnesian limestones, again, exhibit no striking external peculiarities by which the presence of magnesia would be readily recognised, and though the base of the rock is crystalline, they are replete with the remains of organised beings. thus many of the magnesian limestones of the carboniferous series of the north of england are very like ordinary limestone to look at, though effervescing less freely with acids, and the microscope proves them to be charged with the remains of _foraminifera_ and other minute organisms. _marbles_ are of various kinds, all limestones which are sufficiently hard and compact to take a high polish going by this name. statuary marble, and most of the celebrated foreign marbles, are "metamorphic" rocks, of a highly crystalline nature, and having all traces of their primitive organic structure obliterated. many other marbles, however, differ from ordinary limestone simply in the matter of density. thus, many marbles (such as derbyshire marble) are simply "crinoidal limestones" (fig. ); whilst various other british marbles exhibit innumerable organic remains under the microscope. black marbles owe their colour to the presence of very minute particles of carbonaceous matter, in some cases at any rate; and they may either be metamorphic, or they may be charged with minute fossils such as _foraminifera_ (_e.g._, the black limestones of ireland, and the black marble of dent, in yorkshire). [illustration: fig. .--slice of oolitic limestone from the jurassic series (coral rag) of weymouth; magnified. (original.)] "_oolitic_" _limestones_, or "_oolites_," as they are often called, are of interest both to the palæontologist and geologist. the peculiar structure to which they owe their name is that the rock is more or less entirely composed of spheroidal or oval grains, which vary in size from the head of a small pin or less up to the size of a pea, and which may be in almost immediate contact with one another, or may be cemented together by a more or less abundant calcareous matrix. when the grains are pretty nearly spherical and are in tolerably close contact, the rock looks very like the roe of a fish, and the name of "oolite" or "egg-stone" is in allusion to this. when the grains are of the size of peas or upwards, the rock is often called a "pisolite" (lat. _pisum_, a pea). limestones having this peculiar structure are especially abundant in the jurassic formation, which is often called the "oolitic series" for this reason; but essentially similar limestones occur not uncommonly in the silurian, devonian, and carboniferous formations, and, indeed, in almost all rock-groups in which limestones are largely developed. whatever may be the age of the formation in which they occur, and whatever may be the size of their component "eggs," the structure of oolitic limestones is fundamentally the same. all the ordinary oolitic limestones, namely, consist of little spherical or ovoid "concretions," as they are termed, cemented together by a larger or smaller amount of crystalline carbonate of lime, together, in many instances, with numerous organic remains of different kinds (fig. ). when examined in polished slabs, or in thin sections prepared for the microscope, each of these little concretions is seen to consist of numerous concentric coats of carbonate of lime, which sometimes simply surround an imaginary centre, but which, more commonly, have been successively deposited round some foreign body, such as a little crystal of quartz, a cluster of sand-grains, or a minute shell. in other cases, as in some of the beds of the carboniferous limestone in the north of england, where the limestone is highly "arenaceous," there is a modification of the oolitic structure. microscopic sections of these sandy limestones (fig. ) show numerous generally angular or oval grains of silica or flint, each of which is commonly surrounded by a thin coating of carbonate of lime, or sometimes by several such coats, the whole being cemented together along with the shells of _foraminifera_ and other minute fossils by a matrix of crystalline calcite. as compared with typical oolites, the concretions in these limestones are usually much more irregular in shape, often lengthened out and almost cylindrical, at other times angular, the central nucleus being of large size, and the surrounding envelope of lime being very thin, and often exhibiting no concentric structure. in both these and the ordinary oolites, the structure is fundamentally the same. both have been formed in a sea, probably of no great depth, the waters of which were charged with carbonate of lime in solution, whilst the bottom was formed of sand intermixed with minute shells and fragments of the skeletons of larger marine animals. the excess of lime in the sea-water was precipitated round the sand-grams, or round the smaller shells, as so many nuclei, and this precipitation must often have taken place time after time, so as to give rise to the concentric structure so characteristic of oolitic concretions. finally, the oolitic grains thus produced were cemented together by a further precipitation of crystalline carbonate of lime from the waters of the ocean. [illustration: fig. .--slice of arenaceous and oolitic limestone from the carboniferous series of shap, westmoreland; magnified. the section also exhibit _foraminifera_ and other minute fossils. (original.)] _phosphate of lime_ is another lime-salt, which is of interest to the palæontologist. it does not occur largely in the stratified series, but it is found in considerable beds [ ] in the laurentian formation, and less abundantly in some later rock-groups, whilst it occurs abundantly in the form of nodules in parts of the cretaceous (upper greensand) and tertiary deposits. phosphate of lime forms the larger proportion of the earthy matters of the bones of vertebrate animals, and also occurs in less amount in the skeletons of certain of the invertebrates (_e.g._, _crustacea_). it is, indeed, perhaps more distinctively than carbonate of lime, an organic compound; and though the formation of many known deposits of phosphate of lime cannot be positively shown to be connected with the previous operation of living beings, there is room for doubt whether this salt is not in reality always primarily a product of vital action. the phosphatic nodules of the upper greensand are erroneously called "coprolites," from the belief originally entertained that they were the droppings or fossilised excrements of extinct animals; and though this is not the case, there can be little doubt but that the phosphate of lime which they contain is in this instance of organic origin.[ ] it appears, in fact, that decaying animal matter has a singular power of determining the precipitation around it of mineral salts dissolved in water. thus, when any animal bodies are undergoing decay at the bottom of the sea, they have a tendency to cause the precipitation from the surrounding water of any mineral matters which may be dissolved in it; and the organic body thus becomes a centre round which the mineral matters in question are deposited in the form of a "concretion" or "nodule." the phosphatic nodules in question were formed in a sea in which phosphate of lime, derived from the destruction of animal skeletons, was held largely in solution; and a precipitation of it took place round any body, such as a decaying animal substance, which happened to be lying on the sea-bottom, and which offered itself as a favourable nucleus. in the same way we may explain the formation of the calcareous nodules, known as "septaria" or "cement stones," which occur so commonly in the london clay and kimmeridge clay, and in which the principal ingredient is carbonate of lime. a similar origin is to be ascribed to the nodules of clay iron-stone (impure carbonate of iron) which occur so abundantly in the shales of the carboniferous series and in other argillaceous deposits; and a parallel modern example is to be found in the nodules of manganese, which were found by sir wyville thomson, in the challenger, to be so numerously scattered over the floor of the pacific at great depths. in accordance with this mode of origin, it is exceedingly common to find in the centre of all these nodules, both old and new, some organic body, such as a bone, a shell, or a tooth, which acted as the original nucleus of precipitation, and was thus preserved in a shroud of mineral matter. many nodules, it is true, show no such nucleus; but it has been affirmed that all of them can be shown, by appropriate microscopical investigation, to have been formed round an original organic body to begin with (hawkins johnson). [footnote : apart from the occurrence or phosphate of lime in actual beds in the stratified rocks, as in the laurentian and silurian series, this salt may also occur disseminated through the rock, when it can only be detected by chemical analysis. it is interesting to note that dr hicks has recently proved the occurrence of phosphate of lime in this disseminated form in rocks as old as the cambrian, and that in quantity quite equal to what is generally found to be present in the later fossiliferous rocks. this affords a chemical proof that animal life flourished abundantly in the cambrian seas.] [footnote : it has been maintained, indeed, that the phosphatic nodules so largely worked for agricultural purposes, are in themselves actual organic bodies or true fossils. in a few cases this admits of demonstration, as it can be shown that the nodule is simply an organism (such as a sponge) infiltrated with phosphate of lime (sollas); but there are many other cases in which no actual structure has yet been shown to exist, and as to the true origin of which it would be hazardous to offer a positive opinion.] the last lime-salt which need be mentioned is _gypsum_, or _sulphate of lime_. this substance, apart from other modes of occurrence, is not uncommonly found interstratified with the ordinary sedimentary rocks, in the form of more or less irregular beds; and in these cases it has a palæontological importance, as occasionally yielding well-preserved fossils. whilst its exact mode of origin is uncertain, it cannot be regarded as in itself an organic rock, though clearly the product of chemical action. to look at, it is usually a whitish or yellowish-white rock, as coarsely crystalline as loaf-sugar, or more so; and the microscope shows it to be composed entirely of crystals of sulphate of lime. we have seen that the _calcareous_ or lime-containing rocks are the most important of the group of organic deposits; whilst the _siliceous_ or flint-containing rocks may be regarded as the most important, most typical, and most generally distributed of the mechanically-formed rocks. we have, however, now briefly to consider certain deposits which are more or less completely formed of flint; but which, nevertheless, are essentially organic in their origin. flint or silex, hard and intractable as it is, is nevertheless capable of solution in water to a certain extent, and even of assuming, under certain circumstances, a gelatinous or viscous condition. hence, some hot-springs are impregnated with silica to a considerable extent; it is present in small quantity in sea-water; and there is reason to believe that a minute proportion must very generally be present in all bodies of fresh water as well. it is from this silica dissolved in the water that many animals and some plants are enabled to construct for themselves flinty skeletons; and we find that these animals and plants are and have been sufficiently numerous to give rise to very considerable deposits of siliceous matter by the mere accumulation of their skeletons. amongst the animals which require special mention in this connection are the microscopic organisms which are known to the naturalist as _polycystina_. these little creatures are of the lowest possible grade of organisation, very closely related to the animals which we have previously spoken of as _foraminifera_, but differing in the fact that they secrete a shell or skeleton composed of flint instead of lime. the _polycystina_ occur abundantly in our present seas; and their shells are present in some numbers in the ooze which is found at great depths in the atlantic and pacific oceans, being easily recognised by their exquisite shape, their glassy transparency, the general presence of longer or shorter spines, and the sieve-like perforations in the walls. both in barbadoes and in the nicobar islands occur geological formations which are composed of the flinty skeletons of these microscopic animals; the deposit in the former locality attaining a great thickness, and having been long known to workers with the microscope under the name of "barbadoes earth" (fig. ). [illustration: fig. .--shells of _polycystina_ from "barbadoes earth;" greatly magnified. (original.)] [illustration: fig. .--cases of diatoms in the richmond "infusorial earth;" highly magnified. (original.)] in addition to flint-producing animals, we have also the great group of fresh-water and marine microscopic plants known as _diatoms_, which likewise secrete a siliceous skeleton, often of great beauty. the skeletons of diatoms are found abundantly at the present day in lake-deposits, guano, the silt of estuaries, and in the mud which covers many parts of the sea-bottom; they have been detected in strata of great age; and in spite of their microscopic dimensions, they have not uncommonly accumulated to form deposits of great thickness, and of considerable superficial extent. thus the celebrated deposit of "tripoli" ("polir-schiefer") of bohemia, largely worked as polishing-powder, is composed wholly, or almost wholly, of the flinty cases of diatoms, of which it is calculated that no less than forty-one thousand millions go to make up a single cubic inch of the stone. another celebrated deposit is the so-called "infusorial earth" of richmond in virginia, where there is a stratum in places thirty feet thick, composed almost entirely of the microscopic shells of diatoms. nodules or layers of _flint_, or the impure variety of flint known as _chert_, are found in limestones of almost all ages from the silurian upwards; but they are especially abundant in the chalk. when these flints are examined in thin and transparent slices under the microscope, or in polished sections, they are found to contain an abundance of minute organic bodies--such as _foraminifera_, sponge-spicules, &c.--embedded in a siliceous basis. in many instances the flint contains larger organisms--such as a sponge or a sea-urchin. as the flint has completely surrounded and infiltrated the fossils which it contains, it is obvious that it must have been deposited from sea-water in a gelatinous condition, and subsequently have hardened. that silica is capable of assuming this viscous and soluble condition is known; and the formation of flint may therefore be regarded as due to the separation of silica from the sea-water and its deposition round some organic body in a state of chemical change or decay, just as nodules of phosphate of lime or carbonate of iron are produced. the existence of numerous organic bodies in flint has long been known; but it should be added that a recent observer (mr hawkins johnson) asserts that the existence of an organic structure can be demonstrated by suitable methods of treatment, even in the actual matrix or basis of the flint.[ ] [footnote : it has been asserted that the flints of the chalk are merely fossil sponges. no explanation of the origin of flint, however, can be satisfactory, unless it embraces the origin of chert in almost all great limestones from the silurian upwards, as well as the common phenomenon of the silicification of organic bodies (such as corals and shells) which are known with certainty to have been originally calcareous.] in addition to deposits formed of flint itself, there are other siliceous deposits formed by certain _silicates_, and also of organic origin. it has been shown, namely--by observations carried out in our present seas--that the shells of _foraminifera_ are liable to become completely infiltrated by silicates (such as "glauconite," or silicate of iron and potash). should the actual calcareous shell become dissolved away subsequent to this infiltration--as is also liable to occur--then, in place of the shells of the _foraminifera_, we get a corresponding number of green sandy grains of glauconite, each grain being the _cast_ of a single shell. it has thus been shown that the green sand found covering the sea-bottom in certain localities (as found by the challenger expedition along the line of the agulhas current) is really organic, and is composed of casts of the shells of _foraminifera_. long before these observations had been made, it had been shown by professor ehrenberg that the green sands of various geological formations are composed mainly of the internal casts of the shells of _foraminifera_, and we have thus another and a very interesting example how rock-deposits of considerable extent and of geological importance can be built up by the operation of the minutest living beings. as regards _argillaceous_ deposits, containing _alumina_ or _clay_ as their essential ingredient, it cannot be said that any of these have been actually shown to be of organic origin. a recent observation by sir wyville thomson would, however, render it not improbable that some of the great argillaceous accumulations of past geological periods may be really organic. this distinguished observer, during the cruise of the challenger, showed that the calcareous ooze which has been already spoken of as covering large areas of the floor of the atlantic and pacific at great depths, and which consists almost wholly of the shells of _foraminifera_, gave place at still greater depths to a red ooze consisting of impalpable clayey mud, coloured by oxide of iron, and devoid of traces of organic bodies. as the existence of this widely-diffused red ooze, in mid-ocean, and at such great depths, cannot be explained on the supposition that it is a sediment brought down into the sea by rivers, sir wyville thomson came to the conclusion that it was probably formed by the action of the sea-water upon the shells of _foraminifera_. these shells, though mainly consisting of lime, also contain a certain proportion of alumina, the former being soluble in the carbonic acid dissolved in the sea-water, whilst the latter is insoluble. there would further appear to be grounds for believing that the solvent power of the sea-water over lime is considerably increased at great depths. if, therefore, we suppose the shells of _foraminifera_ to be in course of deposition over the floor of the pacific, at certain depths they would remain unchanged, and would accumulate to form a calcareous ooze; but at greater depths they would be acted upon by the water, their lime would be dissolved out, their form would disappear, and we should simply have left the small amount of alumina which they previously contained. in process of time this alumina would accumulate to form a bed of clay; and as this clay had been directly derived from the decomposition of the shells of animals, it would be fairly entitled to be considered an organic deposit. though not finally established, the hypothesis of sir wyville thomson on this subject is of the greatest interest to the palæontologist, as possibly serving to explain the occurrence, especially in the older formations, of great deposits of argillaceous matter which are entirely destitute of traces of life. it only remains, in this connection, to shortly consider the rock-deposits in which _carbon_ is found to be present in greater or less quantity. in the great majority of cases where rocks are found to contain carbon or carbonaceous matter, it can be stated with certainty that this substance is of organic origin, though it is not necessarily derived from vegetables. carbon derived from the decomposition of animal bodies is not uncommon; though it never occurs in such quantity from this source as it may do when it is derived from plants. thus, many limestones are more or less highly bituminous; the celebrated siliceous flags or so-called "bituminous schists" of caithness are impregnated with oily matter apparently derived from the decomposition of the numerous fishes embedded in them; silurian shales containing graptolites, but destitute of plants, are not uncommonly "anthracitic," and contain a small percentage of carbon derived from the decay of these zoophytes; whilst the petroleum so largely worked in north america has not improbably an animal origin. that the fatty compounds present in animal bodies should more or less extensively impregnate fossiliferous rock-masses, is only what might be expected; but the great bulk of the carbon which exists stored up in the earth's crust is derived from plants; and the form in which it principally presents itself is that of coal. we shall have to speak again, and at greater length, of coal, and it is sufficient to say here that all the true coals, anthracites, and lignites, are of organic origin, and consist principally of the remains of plants in a more or less altered condition. the bituminous shales which are found so commonly associated with beds of coal also derive their carbon primarily from plants; and the same is certainly, or probably, the case with similar shales which are known to occur in formations younger than the carboniferous. lastly, carbon may occur as a conspicuous constituent of rock-masses in the form of _graphite_ or _black-lead_. in this form, it occurs in the shape of detached scales, of veins or strings, or sometimes of regular layers;[ ] and there can be little doubt that in many instances it has an organic origin, though this is not capable of direct proof. when present, at any rate, in quantity, and in the form of layers associated with stratified rocks, as is often the case in the laurentian formation, there can be little hesitation in regarding it as of vegetable origin, and as an altered coal. [footnote : in the huronian formation at steel river, on the north shore of lake superior, there exists a bed of carbonaceous matter which is regularly interstratified with the surrounding rocks, and has a thickness of from to feet. this bed is shown by chemical analysis to contain about per cent of carbon, partly in the form of graphite, partly in the form of anthracite; and there can be little doubt but that it is really a stratum of "metamorphic" coal.] chapter iii. chronological succession of the fossiliferous rocks. the physical geologist, who deals with rocks simply as rocks, and who does not necessarily trouble himself about what fossils they may contain, finds that the stratified deposits which form so large a portion of the visible part of the earth's crust are not promiscuously heaped together, but that they have a certain definite arrangement. in each country that he examines, he finds that certain groups of strata lie above certain other groups; and in comparing different countries with one another, he finds that, in the main, the same groups of rocks are always found in the same relative position to each other. it is possible, therefore, for the physical geologist to arrange the known stratified rocks into a successive series of groups, or "formations," having a certain definite order. the establishment of this physical order amongst the rocks introduces, however, at once the element of _time_, and the physical succession of the strata can be converted directly into a historical or _chronological_ succession. this is obvious, when we reflect that any bed or set of beds of sedimentary origin is clearly and necessarily younger than all the strata upon which it rests, and older than all those by which it is surmounted. it is possible, then, by an appeal to the rocks alone, to determine in each country the general physical succession of the strata, and this "stratigraphical" arrangement, when once determined, gives us the _relative_ ages of the successive groups. the task, however, of the physical geologist in this matter is immensely lightened when he calls in palæontology to his aid, and studies the evidence of the fossils embedded in the rocks. not only is it thus much easier to determine the order of succession of the strata in any given region, but it becomes now for the first time possible to compare, with certainty and precision, the order of succession in one region with that which exists in other regions far distant. the value of fossils as tests of the relative ages of the sedimentary rocks depends on the fact that they are not indefinitely or promiscuously scattered through the crust of the earth,--as it is conceivable that they might be. on the contrary, the first and most firmly established law of palæontology is, that _particular kinds of fossils are confined to particular rocks_, and _particular groups of fossils are confined to particular groups of rocks_. fossils, then, are distinctive of the rocks in which they are found--much more distinctive, in fact, than the mere mineral character of the rock can be, for _that_ commonly changes as a formation is traced from one region to another, whilst the fossils remain unaltered. it would therefore be quite possible for the palæontologist, by an appeal to the fossils alone, to arrange the series of sedimentary deposits into a pile of strata having a certain definite order. not only would this be possible, but it would be found--if sufficient knowledge had been brought to bear on both sides--that the palæontological arrangement of the strata would coincide in its details with the stratigraphical or physical arrangement. happily for science, there is no such division between the palæontologist and the physical geologist as here supposed; but by the combined researches of the two, it has been found possible to divide the entire series of stratified deposits into a number of definite _rock-groups_ or _formations_, which have a recognised order of succession, and each of which is characterised by possessing an assemblage of organic remains which do not occur in association in any other formation. such an _assemblage of fossils_, characteristic of any given formation, represents the _life_ of the particular _period_ in which the formation was deposited. in this way the past history of the earth becomes divided into a series of successive _life-periods_, each of which corresponds with the deposition of a particular _formation_ or group of strata. whilst particular _assemblages_ of organic forms characterise particular _groups_ of rocks, it may be further said that, in a general way, each subdivision of each formation has its own peculiar fossils, by which it may be recognised by a skilled worker in palæontology. whenever, for instance, we meet with examples of the fossils which are known as _graptolites_, we may be sure that we are dealing with _silurian_ rocks (leaving out of sight one or two forms doubtfully referred to this family). we may, however, go much farther than this with perfect safety. if the graptolites belong to certain genera, we may be quite certain that we are dealing with _lower_ silurian rocks. furthermore, if certain special forms are present, we may be even able to say to what exact subdivision of the lower silurian series they belong. as regards particular fossils, however, or even particular classes of fossils, conclusions of this nature require to be accompanied by a tacit but well-understood reservation. so far as our present observation goes, none of the undoubted graptolites have ever been discovered in rocks later than those known upon other grounds to be silurian; but it is possible that they might at any time be detected in younger deposits. similarly, the species and genera which we now regard as characteristic of the lower silurian, may at some future time be found to have survived into the upper silurian period. we should not forget, therefore, in determining the age of strata by palæontological evidence, that we are always reasoning upon generalisations which are the result of experience alone, and which are liable to be vitiated by further and additional discoveries. when the palæontological evidence as to the age of any given set of strata is corroborated by the physical evidence, our conclusions may be regarded as almost certain; but there are certain limitations and fallacies in the palæontological method of inquiry which deserve a passing mention. in the first place, fossils are not always present in the stratified rocks; many aqueous rocks are unfossiliferous, through a thickness of hundreds or even thousands of feet of little-altered sediments; and even amongst beds which do contain fossils, we often meet with strata of many feet or yards in thickness which are wholly destitute of any traces of fossils. there are, therefore, to begin with, many cases in which there is no palæontological evidence extant or available as to the age of a given group of strata. in the second place, palæontological observers in different parts of the world are liable to give different names to the same fossil, and in all parts of the world they are occasionally liable to group together different fossils under the same title. both these sources of fallacy require to be guarded against in reasoning as to the age of strata from their fossil remains. thirdly, the mere fact of fossils being found in beds which are known by physical evidence to be of different ages, has commonly led palæontologists to describe them as different species. thus, the same fossil, occurring in successive groups of strata, and with the merely trivial and varietal differences due to the gradual change in its environment, has been repeatedly described as a distinct species, with a distinct name, in every bed in which it was found. we know, however, that many fossils range vertically through many groups of strata, and there are some which even pass through several formations. the mere fact of a difference of physical position ought never to be taken into account at all in considering and determining the true affinities of a fossil. fourthly, the results of experience, instead of being an assistance, are sometimes liable to operate as a source of error. when once, namely, a generalisation has been established that certain fossils occur in strata of a certain age, palæontologists are apt to infer that _all_ beds containing similar fossils must be of the same age. there is a presumption, of course, that this inference would be correct; but it is not a conclusion resting upon absolute necessity, and there might be physical evidence to disprove it. fifthly, the physical geologist may lead the palæontologist astray by asserting that the physical evidence as to the age and position of a given group of beds is clear and unequivocal, when such evidence may be, in reality, very slight and doubtful. in this way, the observer may be readily led into wrong conclusions as to the nature of the organic remains--often obscure and fragmentary--which it is his business to examine, or he may be led erroneously to think that previous generalisations as to the age of certain kinds of fossils are premature and incorrect. lastly, there are cases in which, owing to the limited exposure of the beds, to their being merely of local development, or to other causes, the physical evidence as to the age of a given group of strata may be entirely uncertain and unreliable, and in which, therefore, the observer has to rely wholly upon the fossils which he may meet with. in spite of the above limitations and fallacies, there can be no doubt as to the enormous value of palæontology in enabling us to work out the historical succession of the sedimentary rocks. it may even be said that in any case where there should appear to be a clear and decisive discordance between the physical and the palæontological evidence as to the age of a given series of beds, it is the former that is to be distrusted rather than the latter. the records of geological science contain not a few cases in which apparently clear physical evidence of superposition has been demonstrated to have been wrongly interpreted; but the evidence of palæontology, when in any way sufficient, has rarely been upset by subsequent investigations. should we find strata containing plants of the coal-measures apparently resting upon other strata with ammonites and belemnites, we may be sure that the physical evidence is delusive; and though the above is an extreme case, the presumption in all such instances is rather that the physical succession has been misunderstood or misconstrued, than that there has been a subversion of the recognised succession of life-forms. we have seen, then, that as the collective result of observations made upon the superposition of rocks in different localities, from their mineral characters, and from their included fossils, geologists have been able to divide the entire stratified series into a number of different divisions or formations, each characterised by a _general_ uniformity of mineral composition, and by a special and peculiar _assemblage_ of organic forms. each of these primary groups is in turn divided into a series of smaller divisions, characterised and distinguished in the same way. it is not pretended for a moment that all these primary rock-groups can anywhere be seen surmounting one another regularly.[ ] there is no region upon the earth where all the stratified formations can be seen together; and, even when most of them occur in the same country, they can nowhere be seen all succeeding each other in their regular and uninterrupted succession. the reason of this is obvious. there are many places--to take a single example--where one may see the the silurian rocks, the devonian, and the carboniferous rocks succeeding one another regularly, and in their proper order. this is because the particular region where this occurs was always submerged beneath the sea while these formations were being deposited. there are, however, many more localities in which one would find the carboniferous rocks resting unconformably upon the silurians without the intervention of any strata which could be referred to the devonian period. this might arise from one of two causes: . the silurians might have been elevated above the sea immediately after their deposition, so as to form dry land during the whole of the devonian period, in which case, of course, no strata of the latter age could possibly be deposited in that area. . the devonian might have been deposited upon the silurian, and then the whole might have been elevated above the sea, and subjected to an amount of denudation sufficient to remove the devonian strata entirely. in this case, when the land was again submerged, the carboniferous rocks, or any younger formation, might be deposited directly upon silurian strata. from one or other of these causes, then, or from subsequent disturbances and denudations, it happens that we can rarely find many of the primary formations following one another consecutively and in their regular order. [footnote : as we have every reason to believe that dry land and sea have existed, at any rate from the commencement of the laurentian period to the present day, it is quite obvious that no one of the great formations can ever, under any circumstances, have extended over the entire globe. in other words, no one of the formations can ever have had a greater geographical extent than that of the seas of the period in which the formation was deposited. nor is there any reason for thinking that the proportion of dry land to ocean has ever been materially different to what it is at present, however greatly the areas of sea and land may have changed as regards their place. it follows from the above, that there is no sufficient basis for the view that the crust of the earth is composed of a succession of concentric layers, like the coats of an onion, each layer representing one formation.] in no case, however, do we ever find the devonian resting upon the carboniferous, or the silurian rocks reposing on the devonian. we have therefore, by a comparison of many different areas, an established order of succession of the stratified formations, as shown in the subjoined ideal section of the crust of the earth (fig. ). the main subdivisions of the stratified rocks are known by the following names:-- . laurentian. . cambrian (with huronian ?). . silurian. . devonian or old red sandstone. . carboniferous. . permian \_ new red sandstone. . triassic / . jurassic or oolitic. . cretaceous. . eocene. . miocene. . pliocene. . post-tertiary. [illustration: fig. . ideal section of the crust of the earth.] of these primary rock divisions, the laurentian, cambrian, silurian, devonian, carboniferous, and permian are collectively grouped together under the name of the primary or _paloeozoic_ rocks (gr. _palaios_, ancient; _zoe_, life). not only do they constitute the oldest stratified accumulations, but from the extreme divergence between their animals and plants and those now in existence, they may appropriately be considered as belonging to an "old-life" period of the world's history. the triassic, jurassic, and cretaceous systems are grouped together as the _secondary_ or _mesozoic_ formations (gr. _mesos_, intermediate; _zoe_, life); the organic remains of this "middle-life" period being, on the whole, intermediate in their characters between those of the palæozoic epoch and those of more modern strata. lastly, the eocene, miocene, and pliocene formations are grouped together as the _tertiary_ or _kainozoic_ rocks (gr. _kainos_, new; _zoe_, life); because they constitute a "new-life" period, in which the organic remains approximate in character to those now existing upon the globe. the so-called _post-tertiary_ deposits are placed with the kainozoic, or may be considered as forming a separate _quaternary_ system. chapter iv. the breaks in the geological and palÆontological record. the term "contemporaneous" is usually applied by geologists to groups of strata in different regions which contain the same fossils, or an assemblage of fossils in which many identical forms are present. that is to say, beds which contain identical, or nearly identical, fossils, however widely separated they may be from one another in point of actual distance, are ordinarily believed to have been deposited during the same period of the earth's history. this belief, indeed, constitutes the keystone of the entire system of determining the age of strata by their fossil contents; and if we take the word "contemporaneous" in a general and strictly geological sense, this belief can be accepted as proved beyond denial. we must, however, guard ourselves against too literal an interpretation of the word "contemporaneous," and we must bear in mind the enormously-prolonged periods of time with which the geologist has to deal. when we say that two groups of strata in different regions are "contemporaneous," we simply mean that they were formed during the same geological period, and perhaps at different stages of that period, and we do not mean to imply that they were formed at precisely the same instant of time. a moment's consideration will show us that it is only in the former sense that we can properly speak of strata being "contemporaneous;" and that, in point of fact, beds containing the same fossils, if occurring in widely distant areas, can hardly be "contemporaneous" in any literal sense; but that the very identity of their fossils is proof that they were deposited one after the other. if we find strata containing identical fossils within the limits of a single geographical region--say in europe--then there is a reasonable probability that these beds are strictly contemporaneous, in the sense that they were deposited at the same time. there is a reasonable probability of this, because there is no improbability involved in the idea of an ocean occupying the whole area of europe, and peopled throughout by many of the same species of marine animals. at the present day, for example, many identical species of animals are found living on the western coasts of britain and the eastern coasts of north america, and beds now in course of deposition off the shores of ireland and the seaboard of the state of new york would necessarily contain many of the same fossils. such beds would be both literally and geologically contemporaneous; but the case is different if the distance between the areas where the strata occur be greatly increased. we find, for example, beds containing identical fossils (the quebec or skiddaw beds) in sweden, in the north of england, in canada, and in australia. now, if all these beds were contemporaneous, in the literal sense of the term, we should have to suppose that the ocean at one time extended uninterruptedly between all these points, and was peopled throughout the vast area thus indicated by many of the same animals. nothing, however, that we see at the present day would justify us in imagining an ocean of such enormous extent, and at the same time so uniform in its depth, temperature, and other conditions of marine life, as to allow the same animals to flourish in it from end to end; and the example chosen is only one of a long and ever-recurring series. it is therefore much more reasonable to explain this, and all similar cases, as owing to the _migration_ of the fauna, in whole or in part, from one marine area to another. thus, we may suppose an ocean to cover what is now the european area, and to be peopled by certain species of animals. beds of sediment--clay, sands, and limestones--will be deposited over the sea-bottom, and will entomb the remains of the animals as fossils. after this has lasted for a certain length of time, the european area may undergo elevation, or may become otherwise unsuitable for the perpetuation of its fauna; the result of which would be that some or all of the marine animals of the area would migrate to some more suitable region. sediments would then be accumulated in the new area to which they had betaken themselves, and they would then appear, for the second time, as fossils in a set of beds widely separated from europe. the second set of beds would, however, obviously not be strictly or literally contemporaneous with the first, but would be separated from them by the period of time required for the migration of the animals from the one area into the other. it is only in a wide and comprehensive sense that such strata can be said to be contemporaneous. it is impossible to enter further into this subject here; but it may be taken as certain that beds in widely remote geographical areas can only come to contain the same fossils by reason of a migration having taken place of the animals of the one area to the other. that such migrations can and do take place is quite certain, and this is a much more reasonable explanation of the observed facts than the hypothesis that in former periods the conditions of life were much more uniform than they are at present, and that, consequently, the same organisms were able to range over the entire globe at the same time. it need only be added, that taking the evidence of the present as explaining the phenomena of the past--the only safe method of reasoning in geological matters--we have abundant proof that deposits which _are_ actually contemporaneous, in the strict sense of the term, _do not contain the same fossils, if far removed from one another in point of distance_. thus, deposits of various kinds are now in process of formation in our existing seas, as, for example, in the arctic ocean, the atlantic, and the pacific, and many of these deposits are known to us by actual examination and observation with the sounding-lead and dredge. but it is hardly necessary to add that the animal remains contained in these deposits--the fossils of some future period--instead of being identical, are widely different from one another in their characters. we have seen, then, that the entire stratified series is capable of subdivision into a number of definite rock-groups or "formations," each possessing a peculiar and characteristic assemblage of fossils, representing the "life" of the "period" in which the formation was deposited. we have still to inquire shortly how it came to pass that two successive formations _should_ thus be broadly distinguished by their life-forms, and why they should not rather possess at any rate a majority of identical fossils. it was originally supposed that this could be explained by the hypothesis that the close of each formation was accompanied by a general destruction of all the living beings of the period, and that the commencement of each new formation was signalised by the creation of a number of brand-new organisms, destined to figure as the characteristic fossils of the same. this theory, however, ignores the fact that each formation--as to which we have any sufficient evidence--contains a few, at least, of the life-forms which existed in the preceding period; and it invokes forces and processes of which we know nothing, and for the supposed action of which we cannot account. the problem is an undeniably difficult one, and it will not be possible here to give more than a mere outline of the modern views upon the subject. without entering into the at present inscrutable question as to the manner in which new life-forms are introduced upon the earth, it may be stated that almost all modern geologists hold that the living beings of any given formation are in the main modified forms of others which have preceded them. it is not believed that any general or universal destruction of life took place at the termination of each geological period, or that a general introduction of new forms took place at the commencement of a new period. it is, on the contrary, believed that the animals and plants of any given period are for the most part (or exclusively) the lineal but modified descendants of the animals and plants of the immediately preceding period, and that some of them, at any rate, are continued into the next succeeding period, either unchanged, or so far altered as to appear as new species. to discuss these views in detail would lead us altogether too far, but there is one very obvious consideration which may advantageously receive some attention. it is obvious, namely, that the great discordance which is found to subsist between the animal life of any given formation and that of the next succeeding formation, and which no one denies, would be a fatal blow to the views just alluded to, unless admitting of some satisfactory explanation. nor is this discordance one purely of life-forms, for there is often a physical break in the successions of strata as well. let us therefore briefly consider how far these interruptions and breaks in the geological and palæontological record can be accounted for, and still allow us to believe in some theory of continuity as opposed to the doctrine of intermittent and occasional action. in the first place, it is perfectly clear that if we admit the conception above mentioned of a continuity of life from the laurentian period to the present day, we could never _prove_ our view to be correct, unless we could produce in evidence fossil examples of _all_ the kinds of animals and plants that have lived and died during that period. in order to do this, we should require, to begin with, to have access to an absolutely unbroken and perfect succession of all the deposits which have ever been laid down since the beginning. if, however, we ask the physical geologist if he is in possession of any such uninterrupted series, he will at once answer in the negative. so far from the geological series being a perfect one, it is interrupted by numerous gaps of unknown length, many of which we can never expect to fill up. nor are the proofs of this far to seek. apart from the facts that we have hitherto examined only a limited portion of the dry land, that nearly two-thirds of the entire area of the globe is inaccessible to geological investigation in consequence of its being covered by the sea, that many deposits can be shown to have been more or less completely destroyed subsequent to their deposition, and that there may be many areas in which living beings exist where no rock is in process of formation, we have the broad fact that rock-deposition only goes on to any extent in water, and that the earth must have always consisted partly of dry land and partly of water--at any rate, so far as any period of which we have geological knowledge is concerned. there _must_, therefore, always have existed, at some part or another of the earth's surface, areas where no deposition of rock was going on, and the proof of this is to be found in the well-known phenomenon of "_unconformability_." whenever, namely, deposition of sediment is continuously going on within the limits of a single ocean, the beds which are laid down succeed one another in uninterrupted and regular sequence. such beds are said to be "conformable," and there are many rock-groups known where one may pass through fifteen or twenty thousand feet of strata without a break--indicating that the beds had been deposited in an area which remained continuously covered by the sea. on the other hand, we commonly find that there is no such regular succession when we pass from one great formation to another, but that, on the contrary, the younger formation rests "unconformably," as it is called, either upon the formation immediately preceding it in point of time, or upon some still older one. the essential physical feature of this unconformability is that the beds of the younger formation rest upon a worn and eroded surface formed by the beds of the older series (fig. ); and a moment's consideration will show us what this indicates. it indicates, beyond the possibility of misconception, that there was an interval between the deposition of the older series and that of the newer series of strata; and that during this interval the older beds were raised above the sea-level, so as to form dry land, and were subsequently depressed again beneath the waters, to receive upon their worn and wasted upper surface the sediments of the later group. during the interval thus indicated, the deposition of rock must of necessity have been proceeding more or less actively in other areas. every unconformity, therefore, indicates that at the spot where it occurs, a more or less extensive series of beds must be actually missing; and though we may sometimes be able to point to these missing strata in other areas, there yet remains a number of unconformities for which we cannot at present supply the deficiency even in a partial manner. [illustration: fig. .--section showing strata of tertiary age (a) resting upon a worn and eroded surface of white chalk (b), the stratification of which is marked by lines of flint.] it follows from the above that the series of stratified deposits is to a greater or less extent irremediably imperfect; and in this imperfection we have one great cause why we can never obtain a perfect series of all the animals and plants that have lived upon the globe. wherever one of these great physical gaps occurs, we find, as we might expect, a corresponding break in the series of life-forms. in other words, whenever we find two formations to be unconformable, we shall always find at the same time that there is a great difference in their fossils, and that many of the fossils of the older formation do not survive into the newer, whilst many of those in the newer are not known to occur in the older. the cause of this is, obviously, that the lapse of time, indicated by the unconformability, has been sufficiently great to allow of the dying out or modification of many of the older forms of life, and the introduction of new ones by immigration. apart, however, altogether, from these great physical breaks and their corresponding breaks in life, there are other reasons why we can never become more than partially acquainted with the former denizens of the globe. foremost amongst these is the fact that an enormous number of animals possess no hard parts of the nature of a skeleton, and are therefore incapable, under any ordinary circumstances, of leaving behind them any traces of their existence. it is true that there are cases in which animals in themselves completely soft-bodied are nevertheless able to leave marks by which their former presence can be detected: thus every geologist is familiar with the winding and twisting "trails" formed on the surface of the strata by sea-worms; and the impressions left by the stranded carcases of jelly-fishes on the fine-grained lithographic slates of solenhofen supply us with an example of how a creature which is little more than "organised sea-water" may still make an abiding mark upon the sands of time. as a general rule, however, animals which have no skeletons are incapable of being preserved as fossils, and hence there must always have been a vast number of different kinds of marine animals of which we have absolutely no record whatever. again, almost all the fossiliferous rocks have been laid down in water; and it is a necessary result of this that the great majority of fossils are the remains of aquatic animals. the remains of air-breathing animals, whether of the inhabitants of the land or of the air itself, are comparatively rare as fossils, and the record of the past existence of these is much more imperfect than is the case with animals living in water. moreover, the fossiliferous deposits are not only almost exclusively aqueous formations, but the great majority are marine, and only a comparatively small number have been formed by lakes and rivers. it follows from the foregoing that the palæontological record is fullest and most complete so far as sea-animals are concerned, though even here we find enormous gaps, owing to the absence of hard structures in many great groups; of animals inhabiting fresh waters our knowledge is rendered still further incomplete by the small proportion that fluviatile and lacustrine deposits bear to marine; whilst we have only a fragmentary acquaintance with the air-breathing animals which inhabited the earth during past ages. lastly, the imperfection of the palæontological record, due to the causes above enumerated, is greatly aggravated, especially as regards the earlier portion of the earth's history, by the fact that many rocks which contained fossils when deposited have since been rendered barren of organic remains. the principal cause of this common phenomenon is what is known as "metamorphism"--that is, the subjection of the rock to a sufficient amount of heat to cause a rearrangement of its particles. when at all of a pronounced character, the result of metamorphic action is invariably the obliteration of any fossils which might have been originally present in the rock. metamorphism may affect rocks of any age, though naturally more prevalent in the older rocks, and to this cause must be set down an irreparable loss of much fossil evidence. the most striking example which is to be found of this is the great laurentian series, which comprises some , feet of highly-metamorphosed sediments, but which, with one not wholly undisputed exception, has as yet yielded no remains of living beings, though there is strong evidence of the former existence in it of fossils. upon the whole, then, we cannot doubt that the earth's crust, so far as yet deciphered by us, presents us with but a very imperfect record of the past. whether the known and admitted imperfections of the geological and palæontological records are sufficiently serious to account satisfactorily for the deficiency of direct evidence recognisable in some modern hypotheses, may be a matter of individual opinion. there can, however, be little doubt that they are sufficiently extensive to throw the balance of evidence decisively in favour of some theory of _continuity_, as opposed to any theory of intermittent and occasional action. the apparent breaks which divide the great series of the stratified rocks into a number of isolated formations, are not marks of mighty and general convulsions of nature, but are simply indications of the imperfection of our knowledge. never, in all probability, shall we be able to point to a complete series of deposits, or a complete succession of life linking one great geological period to another. nevertheless, we may well feel sure that such deposits and such an unbroken succession must have existed at one time. we are compelled to believe that nowhere in the long series of the fossiliferous rocks has there been a total break, but that there must have been a complete continuity of life, and a more or less complete continuity of sedimentation, from the laurentian period to the present day. one generation hands on the lamp of life to the next, and each system of rocks is the direct offspring of those which preceded it in time. though there has not been continuity in any given area, still the geological chain could never have been snapped at one point, and taken up again at a totally different one. thus we arrive at the conviction that _continuity_ is the fundamental law of geology, as it is of the other sciences, and that the lines of demarcation between the great formations are but gaps in our own knowledge. chapter v. conclusions to be drawn from fossils. we have already seen that geologists have been led by the study of fossils to the all-important generalisation that the vast series of the fossiliferous or sedimentary rocks may be divided into a number of definite groups or "formations," each of which is characterised by its organic remains. it may simply be repeated here that these formations are not properly and strictly characterised by the occurrence in them of any one particular fossil. it may be that a formation contains some particular fossil or fossils not occurring out of that formation, and that in this way an observer may identify a given group with tolerable certainty. it very often happens, indeed, that some particular stratum, or sub-group of a series, contains peculiar fossils, by which its existence may be determined in various localities. as before remarked, however, the great formations are characterised properly by the association of certain fossils, by the predominance of certain families or orders, or by an _assemblage_ of fossil remains representing the "life" of the period in which the formation was deposited. fossils, then, enable us to determine the _age_ of the deposits in which they occur. fossils further enable us to come to very important conclusions as to the mode in which the fossiliferous bed was deposited, and thus as to the condition of the particular district or region occupied by the fossiliferous bed at the time of the formation of the latter. if, in the first place, the bed contain the remains of animals such as now inhabit rivers, we know that it is "fluviatile" in its origin, and that it must at one time have either formed an actual riverbed, or been deposited by the overflowing of an ancient stream. secondly, if the bed contain the remains of shellfish, minute crustaceans, or fish, such as now inhabit lakes, we know that it is "lacustrine," and was deposited beneath the waters of a former lake. thirdly, if the bed contain the remains of animals such as now people the ocean, we know that it is "marine" in its origin, and that it is a fragment of an old sea-bottom. we can, however, often determine the conditions under which a bed was deposited with greater accuracy than this. if, for example, the fossils are of kinds resembling the marine animals now inhabiting shallow waters, if they are accompanied by the detached relics of terrestrial organisms, or if they are partially rolled and broken, we may conclude that the fossiliferous deposit was laid down in a shallow sea, in the immediate vicinity of a coast-line, or as an actual shore-deposit. if, again, the remains are those of animals such as now live in the deeper parts of the ocean, and there is a very sparing intermixture of extraneous fossils (such as the bones of birds or quadrupeds, or the remains of plants), we may presume that the deposit is one of deep water. in other cases, we may find, scattered through the rock, and still in their natural position, the valves of shells such as we know at the present day as living buried in the sand or mud of the sea-shore or of estuaries. in other cases, the bed may obviously have been an ancient coral-reef, or an accumulation of social shells, like oysters. lastly, if we find the deposit to contain the remains of marine shells, but that these are dwarfed of their fair proportions and distorted in figure, we may conclude that it was laid down in a brackish sea, such as the baltic, in which the proper saltness was wanting, owing to its receiving an excessive supply of fresh water. in the preceding, we have been dealing simply with the remains of aquatic animals, and we have seen that certain conclusions can be accurately reached by an examination of these. as regards the determination of the conditions of deposition from the remains of aerial and terrestrial animals, or from plants, there is not such an absolute certainty. the remains of land-animals would, of course, occur in "sub-aerial" deposits--that is, in beds, like blown sand, accumulated upon the land. most of the remains of land-animals, however, are found in deposits which have been laid down in water, and they owe their present position to the fact that their former owners were drowned in rivers or lakes, or carried out to sea by streams. birds, flying reptiles, and flying mammals might also similarly find their way into aqueous deposits; but it is to be remembered that many birds and mammals habitually spend a great part of their time in the water, and that these might therefore be naturally expected to present themselves as fossils in sedimentary rocks. plants, again, even when undoubtedly such as must have grown on land, do not prove that the bed in which they occur was formed on land. many of the remains of plants known to us are extraneous to the bed in which they are now found, having reached their present site by falling into lakes or rivers, or being carried out to sea by floods or gales of wind. there are, however, many cases in which plants have undoubtedly grown on the very spot where we now find them. thus it is now generally admitted that the great coal-fields of the carboniferous age are the result of the growth _in situ_ of the plants which compose coal, and that these grew on vast marshy or partially submerged tracts of level alluvial land. we have, however, distinct evidence of old land-surfaces, both in the coal-measures and in other cases (as, for instance, in the well-known "dirt-bed" of the purbeck series). when, for example, we find the erect stumps of trees standing at right angles to the surrounding strata, we know that the surface through which these send their roots was at one time the surface of the dry land, or, in other words, was an ancient soil (fig. ). [illustration: fig. .--erect tree containing reptilian remains. coal-measures, nova scotia. (after dawson.) in many cases fossils enable us to come to important conclusions as to the climate of the period in which they lived but only a few instances of this can be here adduced. as fossils in the majority of instances are the remains of marine animals, it is mostly the temperature of the sea which can alone be determined in this way; and it is important to remember that, owing to the existence of heated currents, the marine climate of a given area does not necessarily imply a correspondingly warm climate in the neighbouring land. land-climates can only be determined by the remains of land-animals or land-plants, and these are comparatively rare as fossils. it is also important to remember that all conclusions on this head are really based upon the present distribution of animal and vegetable life on the globe, and are therefore liable to be vitiated by the following considerations:-- a. most fossils are extinct, and it is not certain that the habits and requirements of any extinct animal were exactly similar to those of its nearest living relative. b. when we get very far back in time, we meet with groups of organisms so unlike anything we know at the present day as to render all conjectures as to climate founded upon their supposed habits more or less uncertain and unsafe. c. in the case of marine animals, we are as yet very far from knowing the exact limits of distribution of many species within our present seas; so that conclusions drawn from living forms as to extinct species are apt to prove incorrect. for instance, it has recently been shown that many shells formerly believed to be confined to the arctic seas have, by reason of the extension of polar currents, a wide range to the south; and this has thrown doubt upon the conclusions drawn from fossil shells as to the arctic conditions under which certain beds were supposed to have been deposited. d. the distribution of animals at the present day is certainly dependent upon other conditions beside climate alone; and the causes which now limit the range of given animals are certainly such as belong to the existing order of things. but the establishment of the present order of things does not date back in many cases to the introduction of the present species of animals. even in the case, therefore, of existing species of animals, it can often be shown that the past distribution of the species was different formerly to what it is now, not necessarily because the climate has changed, but because of the alteration of other conditions essential to the life of the species or conducing to its extension. still, we are in many cases able to draw completely reliable conclusions as to the climate of a given geological period, by an examination of the fossils belonging to that period. among the more striking examples of how the past climate of a region may be deduced from the study of the organic remains contained in its rocks, the following may be mentioned: it has been shown that in eocene times, or at the commencement of the tertiary period, the climate of what is now western europe was of a tropical or sub-tropical character. thus the eocene beds are found to contain the remains of shells such as now inhabit tropical seas, as, for example, cowries and volutes; and with these are the fruits of palms, and the remains of other tropical plants. it has been shown, again, that in miocene times, or about the middle of the tertiary period, central europe was peopled with a luxuriant flora resembling that of the warmer parts of the united states, and leading to the conclusion that the mean annual temperature must have been at least ° hotter than it is at present. it has been shown that, at the same time, greenland, now buried beneath a vast ice-shroud, was warm enough to support a large number of trees, shrubs, and other plants, such as inhabit temperate regions of the globe. lastly, it has been shown upon physical as well as palæontological evidence, that the greater part of the north temperate zone, at a comparatively recent geological period, has been visited with all the rigours of an arctic climate, resembling that of greenland at the present day. this is indicated by the occurrence of arctic shells in the superficial deposits of this period, whilst the musk-ox and the reindeer roamed far south of their present limits. lastly, it was from the study of fossils that geologists learnt originally to comprehend a fact which may be regarded as of cardinal importance in all modern geological theories and speculations--namely, that the crust of the earth is liable to local elevations and subsidences. for long after the remains of shells and other marine animals were for the first time observed in the solid rocks forming the dry land, and at great heights above the sea-level, attempts were made to explain this almost unintelligible phenomenon upon the hypothesis that the fossils in question were not really the objects they represented, but were in truth mere _lusus naturoe_, due to some "plastic virtue latent in the earth." the common-sense of scientific men, however, soon rejected this idea, and it was agreed by universal consent that these bodies really were remains of animals which formerly lived in the sea. when once this was admitted, the further steps were comparatively easy, and at the present day no geological doctrine stands on a firmer basis than that which teaches us that our present continents and islands, fixed and immovable as they appear, have been repeatedly sunk beneath the ocean. chapter vi. the biological relations of fossils. not only have fossils, as we have seen, a most important bearing upon the sciences of geology and physical geography, but they have relations of the most complicated and weighty character with the numerous problems connected with the study of living beings, or in other words, with the science of biology. to such an extent is this the case, that no adequate comprehension of zoology and botany, in their modern form, is so much as possible without some acquaintance with the types of animals and plants which have passed away. there are also numerous speculative questions in the domain of vital science, which, if soluble at all, can only hope to find their key in researches carried out on extinct organisms. to discuss fully the biological relations of fossils would, therefore, afford matter for a separate treatise; and all that can be done here is to indicate very cursorily the principal points to which the attention of the palæontological student ought to be directed. in the first place, the great majority of fossil animals and plants are "extinct"--that is to say, they belong to species which are no longer in existence at the present day. so far, however, from there being any truth in the old view that there were periodic destructions of all the living beings in existence upon the earth, followed by a corresponding number of new creations of animals and plants, the actual facts of the case show that the extinction of old forms and the introduction of new forms have been processes constantly going on throughout the whole of geological time. every species seems to come into being at a certain definite point of time, and to finally disappear at another definite point; though there are few instances indeed, if there are any, in which our present knowledge would permit us safely to fix with precision the times of entrance and exit. there are, moreover, marked differences in the actual time during which different species remained in existence, and therefore corresponding differences in their "vertical range," or, in other words, in the actual amount and thickness of strata through which they present themselves as fossils. some species are found to range through two or even three formations, and a few have an even more extended life. more commonly the species which begin in the commencement of a great formation die out at or before its close, whilst those which are introduced for the first time near the middle or end of the formation may either become extinct, or may pass on into the next succeeding formation. as a general rule, it is the animals which have the lowest and simplest organisation that have the longest range in time, and the additional possession of microscopic or minute dimensions seems also to favour longevity. thus some of the _foraminifera_ appear to have survived, with little or no perceptible alteration, from the silurian period to the present day; whereas large and highly-organised animals, though long-lived as _individuals_, rarely seem to live long _specifically_, and have, therefore, usually a restricted vertical range. exceptions to this, however, are occasionally to be found in some "persistent types," which extend through a succession of geological periods with very little modification. thus the existing lampshells of the genus _lingula_ are little changed from the _linguloe_ which swarmed in the lower silurian seas; and the existing pearly nautilus is the last descendant of a clan nearly as ancient. on the other hand, some forms are singularly restricted in their limits, and seem to have enjoyed a comparatively brief lease of life. an example of this is to be found in many of the _ammonites_--close allies of the nautilus--which are often confined strictly to certain zones of strata, in some cases of very insignificant thickness. of the _causes_ of extinction amongst fossil animals and plants, we know little or nothing. all we can say is, that the attributes which constitute a _species_ do not seem to be intrinsically endowed with permanence, any more than the attributes which constitute an _individual_, though the former may endure whilst many successive generations of the latter have disappeared. each species appears to have its own life-period, its commencement, its culmination, and its gradual decay; and the life-periods of different species may be of very different duration. from what has been said above, it may be gathered that our existing species of animals and plants are, for the most part, quite of modern origin, using the term "modern" in its geological acceptation. measured by human standards, the majority of existing animals (which are capable of being preserved as fossils) are known to have a high antiquity; and some of them can boast of a pedigree which even the geologist may regard with respect. not a few of our shellfish are known to have commenced their existence at some point of the tertiary period; one lampshell (_terebratulina caput-serpentis_) is believed to have survived since the chalk; and some of the _foraminifera_ date, at any rate, from the carboniferous period. we learn from this the additional fact that our existing animals and plants do not constitute an assemblage of organic forms which were introduced into the world collectively and simultaneously, but that they commenced their existence at very different periods, some being extremely old, whilst others may be regarded as comparatively recent animals. and this introduction of the existing fauna and flora was a slow and _gradual_ process, as shown admirably by the study of the fossil shells of the tertiary period. thus, in the earlier tertiary period, we find about per cent of the known fossil shells to be species that are no longer in existence, the remaining per cent being forms which are known to live in our present seas. in the middle of the tertiary period we find many more recent and still existing species of shells, and the extinct types are much fewer in number; and this gradual introduction of forms now living goes on steadily, till, at the close of the tertiary period, the proportions with which we started may be reversed, as many as or per cent of the fossil shells being forms still alive, while not more than per cent may have disappeared. all known animals at the present day may be divided into some five or six primary divisions, which are known technically as "_sub-kingdoms_." each of these sub-kingdoms [ ] may be regarded as representing a certain type or plan of structure, and all the animals comprised in each are merely modified forms of this common type. not only are all known living animals thus reducible to some five or six fundamental plans of structure, but amongst the vast series of fossil forms no one has yet been found--however unlike any existing animal--to possess peculiarities which would entitle it to be placed in a new sub-kingdom. all fossil animals, therefore, are capable of being referred to one or other of the primary divisions of the animal kingdom. many fossil groups have no closely-related group now in existence; but in no case do we meet with any grand structural type which has not survived to the present day. [footnote : in the appendix a brief definition is given of the sub-kingdoms, and the chief divisions of each are enumerated.] the old types of life differ in many respects from those now upon the earth; and the further back we pass in time, the more marked does this divergence become. thus, if we were to compare the animals which lived in the silurian seas with those inhabiting our present oceans, we should in most instances find differences so great as almost to place us in another world. this divergence is the most marked in the palæozoic forms of life, less so in those of the mesozoic period, and less still in the tertiary period. each successive formation has therefore presented us with animals becoming gradually more and more like those now in existence; and though there is an immense and striking difference between the silurian animals and those of to-day, this difference is greatly reduced if we compare the silurian fauna with the devonian; _that_ again with the carboniferous; and so on till we reach the present. it follows from the above that the animals of any given formation are more like those of the next formation below, and of the next formation above, than they are to any others; and this fact of itself is an almost inexplicable one, unless we believe that the animals of any given formation are, in part at any rate, the lineal descendants of the animals of the preceding formation, and the progenitors, also in part at least, of the animals of the succeeding formation. in fact, the palæontologist is so commonly confronted with the phenomenon of closely-allied forms of animal life succeeding one another in point of time, that he is compelled to believe that such forms have been developed from some common ancestral type by some process of "_evolution_." on the other hand, there are many phenomena, such as the apparently sudden introduction of new forms throughout all past time, and the common occurrence of wholly isolated types, which cannot be explained in this way. whilst it seems certain, therefore, that many of the phenomena of the succession of animal life in past periods can only be explained by some law of evolution, it seems at the same time certain that there has always been some other deeper and higher law at work, on the nature of which it would be futile to speculate at present. not only do we find that the animals of each successive formation become gradually more and more like those now existing upon the globe, as we pass from the older rocks into the newer, but we also find that there has been a gradual progression and development in the _types_ of animal life which characterise the geological ages. if we take the earliest-known and oldest examples of any given group of animals, it can sometimes be shown that these primitive forms, though in themselves highly organised, possessed certain characters such as are now only seen in the _young_ of their existing representatives. in technical language, the early forms of life in some instances possess "_embryonic_" characters, though this does not prevent them often attaining a size much more gigantic than their nearest living relatives. moreover, the ancient forms of life are often what is called "comprehensive types"--that is to say, they possess characters in combination such as we nowadays only find separately developed in different, groups of animals. now, this permanent retention of embryonic characters and this "comprehensiveness" of structural type are signs of what a zoologist considers to be a comparatively low grade of organisation; and the prevalence of these features in the earlier forms of animals is a very striking phenomenon, though they are none the less perfectly organised so far as their own type is concerned. as we pass upwards in the geological scale, we find that these features gradually disappear, higher and ever higher forms are introduced, and "specialisation" of type takes the place of the former comprehensiveness. we shall have occasion to notice many of the facts on which these views are based at a later period, and in connection with actual examples. in the meanwhile, it is sufficient to state, as a widely-accepted generalisation of palæontology, that there has been in the past a general progression of organic types, and that the appearance of the lower forms of life has in the main preceded that of the higher forms in point of time. part ii historical palÆontology chapter vii. the laurentian and huronian periods. the _laurentian rocks_ constitute the base of the entire stratified series, and are, therefore, the oldest sediments of which we have as yet any knowledge. they are more largely and more typically developed in north america, and especially in canada, than in any known part of the world, and they derive their title from the range of hills which the old french geographers named the "laurentides." these hills are composed of laurentian rocks, and form the watershed between the valley of the st lawrence river on the one hand, and the great plains which stretch northwards to hudson bay on the other hand. the main area of these ancient deposits forms a great belt of rugged and undulating country, which extends from labrador westwards to lake superior, and then bends northwards towards the arctic sea. throughout this extensive area the laurentian rocks for the most part present themselves in the form of low, rounded, ice-worn hills, which, if generally wanting in actual sublimity, have a certain geological grandeur from the fact that they "have endured the battles and the storms of time longer than any other mountains" (dawson). in some places, however, the laurentian rocks produce scenery of the most magnificent character, as in the great gorge cut through them by the river saguenay, where they rise at times into vertical precipices feet in height. in the famous group of the adirondack mountains, also, in the state of new york, they form elevations no less than feet above the level of the sea. as a general rule, the character of the laurentian region is that of a rugged, rocky, rolling country, often densely timbered, but rarely well fitted for agriculture, and chiefly attractive to the hunter and the miner. as regards its mineral characters, the laurentian series is composed throughout of metamorphic and highly crystalline rocks, which are in a high degree crumpled, folded, and faulted. by the late sir william logan the entire series was divided into two great groups, the _lower laurentian_ and the _upper laurentian_, of which the latter rests unconformably upon the truncated edges of the former, and is in turn unconformably overlaid by strata of huronian and cambrian age (fig. ). [illustration: fig. .--diagrammatic section of the laurentian rocks in lower canada. a lower laurentian; b upper laurentian, resting unconformably upon the lower series; c cambrian strata (potsdam sandstone), resting unconformably on the upper laurentian.] the _lower laurentian_ series attains the enormous thickness of over , feet, and is composed mainly of great beds of gneiss, altered sandstones (quartzites), mica-schist, hornblende-schist, magnetic iron-ore, and hæmatite, together with masses of limestone. the limestones are especially interesting, and have an extraordinary development--three principal beds being known, of which one is not less than feet thick; the collective thickness of the whole being about feet. the _upper laurentian_ series, as before said, reposes unconformably upon the lower laurentian, and attains a thickness of at least , feet. like the preceding, it is wholly metamorphic, and is composed partly of masses of gneiss and quartzite; but it is especially distinguished by the possession of great beds of felspathic rock, consisting principally of "labrador felspar." though typically developed in the great canadian area already spoken of, the laurentian rocks occur in other localities, both in america and in the old world. in britain, the so-called "fundamental gneiss" of the hebrides and of sutherlandshire is probably of lower laurentian age, and the "hypersthene rocks" of the isle of skye may, with great probability, be regarded as referable to the upper laurentian. in other localities in great britain (as in st david's, south wales; the malvern hills; and the north of ireland) occur ancient metamorphic deposits which also are probably referable to the laurentian series. the so-called "primitive gneiss" of norway appears to belong to the laurentian, and the ancient metamorphic rocks of bohemia and bavaria may be regarded as being approximately of the same age. [illustration: fig. .--section of lower laurentian limestone from hull, ottawa; enlarged five diameters. the rock is very highly crystalline, and contains mica and other minerals. the irregular black masses in it are graphite. (original.)] by some geological writers the ancient and highly metamorphosed sediments of the laurentian and the succeeding huronian series have been spoken of as the "azoic rocks" (gr. _a_, without; _zoe_, life); but even if we were wholly destitute of any evidence of life during these periods, this name would be objectionable upon theoretical grounds. if a general name be needed, that of "eozoic" (gr. _eos_, dawn; _zoe_, life), proposed by principal dawson, is the most appropriate. owing to their metamorphic condition, geologists long despaired of ever detecting any traces of life in the vast pile of strata which constitute the laurentian system. even before any direct traces were discovered, it was, however, pointed out that there were good reasons for believing that the laurentian seas had been tenanted by an abundance of living beings. these reasons are briefly as follows:--( ) firstly, the laurentian series consists, beyond question, of marine sediments which originally differed in no essential respect from those which were subsequently laid down in the cambrian or silurian periods. ( ) in all formations later than the laurentian, any limestones which are present can be shown, with few exceptions, to be _organic_ rocks, and to be more or less largely made up of the comminuted debris of marine or fresh-water animals. the laurentian limestones, in consequence of the metamorphism to which they have been subjected, are so highly crystalline (fig. ) that the microscope fails to detect any organic structure in the rock, and no fossils beyond those which will be spoken of immediately have as yet been discovered in them. we know, however, of numerous cases in which limestones, of later age, and undoubtedly organic to begin with, have been rendered so intensely crystalline by metamorphic action that all traces of organic structure have been obliterated. we have therefore, by analogy, the strongest possible ground for believing that the vast beds of laurentian limestone have been originally organic in their origin, and primitively composed, in the main, of the calcareous skeletons of marine animals. it would, in fact, be a matter of great difficulty to account for the formation of these great calcareous masses on any other hypothesis. ( ) the occurrence of phosphate of lime in the laurentian rocks in great abundance, and sometimes in the form of irregular beds, may very possibly be connected with the former existence in the strata of the remains of marine animals of whose skeleton this mineral is a constituent. ( ) the laurentian rocks contain a vast amount of carbon in the form of black-lead or _graphite_. this mineral is especially abundant in the limestones, occurring in regular beds, in veins or strings, or disseminated through the body of the limestone in the shape of crystals, scales, or irregular masses. the amount of graphite in some parts of the lower laurentian is so great that it has been calculated as equal to the quantity of carbon present in an equal thickness of the coal-measures. the general source of solid carbon in the crust of the earth is, however, plant-life; and it seems impossible to account for the laurentian graphite, except upon the supposition that it is metamorphosed vegetable matter. ( ) lastly, the great beds of iron-ore (peroxide and magnetic oxide) which occur in the laurentian series interstratified with the other rocks, point with great probability to the action of vegetable life; since similar deposits in later formations can commonly be shown to have been formed by the deoxidising power of vegetable matter in a state of decay. in the words of principal dawson, "anyone of these reasons might, in itself, be held insufficient to prove so great and, at first sight, unlikely a conclusion as that of the existence of abundant animal and vegetable life in the laurentian; but the concurrence of the whole in a series of deposits unquestionably marine, forms a chain of evidence so powerful that it might command belief even if no fragment of any organic or living form or structure had ever been recognised in these ancient rocks." of late years, however, there have been discovered in the laurentian rocks certain bodies which are believed to be truly the remains of animals, and of which by far the most important is the structure known under the now celebrated name of _eozoön_. if truly organic, a very special and exceptional interest attaches itself to _eozoön_, as being the most ancient fossil animal of which we have any knowledge; but there are some who regard it really a peculiar form of mineral structure, and a severe, protracted, and still unfinished controversy has been carried on as to its nature. into this controversy it is wholly unnecessary to enter here; and it will be sufficient to briefly explain the structure of _eozoön_, as elucidated by the elaborate and masterly investigations of carpenter and dawson, from the standpoint that it is a genuine organism--the balance of evidence up to this moment inclining decisively to this view. [illustration: fig. .--fragment of _eozoön_, of the natural size, showing alternate laminæ of loganite and dolomite. (after dawson.)] the structure known as _eozoön_ is found in various localities in the lower laurentian limestones of canada, in the form of isolated masses or spreading layers, which are composed of thin alternating laminæ, arranged more or less concentrically (fig. ). the laminæ of these masses are usually of different colours and composition; one series being white, and composed of carbonate of lime--whilst the laminæ of the second series alternate with the preceding, are green in colour, and are found by chemical analysis to consist of some silicate, generally serpentine or the closely-related "loganite." in some instances, however, all the laminæ are calcareous, the concentric arrangement still remaining visible in consequence of the fact that the laminæ are composed alternately of lighter and darker coloured limestone. when first discovered, the masses of _eozoön_ were supposed to be of a mineral nature; but their striking general resemblance to the undoubted fossils which will be subsequently spoken of under the name of _stromatopora_ was recognised by sir william logan, and specimens were submitted for minute examination, first to principal dawson, and subsequently to dr w. b. carpenter. after a careful microscopic examination, these two distinguished observers came to the conclusion that _eozoön_ was truly organic, and in this opinion they were afterwards corroborated by other high authorities (mr w. k. parker, professor rupert jones, mr h. b. brady, professor gümbel, &c.) stated briefly, the structure of _eozoön_, as exhibited by the microscope, is as follows:-- [illustration: fig. .--diagram of a portion of _eozoön_ cut vertically. a, b, c, three tiers of chambers communicating with one another by slightly constricted apertures: _a a_, the true shell-wall, perforated by numerous delicate tubes; _b b_. the main calcareous skeleton ("intermediate skeleton"); c, passage of communication ("stolon-passage") from one tier of chambers to another; d, ramifying tubes in the calcareous skeleton. (after carpenter.)] the concentrically-laminated mass of _eozoön_ is composed of numerous calcareous layers, representing the original skeleton of the organism (fig. , b). these calcareous layers serve to separate and define a series of chambers arranged in successive tiers, one above the other (fig. , a, b, c); and they are perforated not only by passages (fig. , c), which serve to place successive tiers of chambers in communication, but also by a system of delicate branching canals (fig. , d). moreover, the central and principal portion of each calcareous layer, with the ramified canal-system just spoken of, is bounded both above and below by a thin lamina which has a structure of its own, and which may be regarded as the proper shell-wall (fig. , a a). this proper wall forms the actual lining of the chambers, as well as the outer surface of the whole mass; and it is perforated with numerous fine vertical tubes (fig. , a a), opening into the chambers and on to the surface by corresponding fine pores. from the resemblance of this tubulated layer to similar structures in the shell of the nummulite, it is often spoken of as the "nummuline layer." the chambers are sometimes piled up one above the other in an irregular manner; but they are more commonly arranged in regular tiers, the separate chambers being marked off from one another by projections of the wall in the form of partitions, which are so far imperfect as to allow of a free communication between contiguous chambers. in the original condition of the organism, all these chambers, of course, must have been filled with living-matter; but they are found in the present state of the fossil to be generally filled with some silicate, such as serpentine, which not only fills the actual chambers, but has also penetrated the minute tubes of the proper wall and the branching canals of the intermediate skeleton. in some cases the chambers are simply filled with crystalline carbonate of lime. when the originally porous fossil has been permeated by a silicate, it is possible to dissolve away the whole of the calcareous skeleton by means of acids, leaving an accurate and beautiful cast of the chambers and the tubes connected with them in the insoluble silicate. [illustration: fig. .--portion of one of the calcareous layers of _eozoön_, magnified diameters. a a, the proper wall ("nummuline layer") of one of the chambers, showing the fine vertical tubuli with which it is penetrated, and which are slightly bent along the line a' a'. c c, the intermediate skeleton, with numerous branched canals. the oblique lines are the cleavage planes of the carbonate of lime, extending across both the intermediate skeleton and the proper wall. (after carpenter.)] the above are the actual appearances presented by _eozoön_ when examined microscopically, and it remains to see how far they enable us to decide upon its true position in the animal kingdom. those who wish to study this interesting subject in detail must consult the admirable memoirs by dr w. b. carpenter and principal dawson: it will be enough here to indicate the results which have been arrived at. the only animals at the present day which possess a continuous calcareous skeleton, perforated by pores and penetrated by canals, are certain organisms belonging to the group of the _foraminifera_. we have had occasion before to speak of these animals, and as they are not conspicuous or commonly-known forms of life, it may be well to say a few words as to the structure of the living representatives of the group. the _foraminifera_ are all inhabitants of the sea, and are mostly of small or even microscopic dimensions. their bodies are composed of an apparently structureless animal substance of an albuminous nature ("sarcode"), of a gelatinous consistence, transparent, and exhibiting numerous minute granules or rounded particles. the body-substance cannot be said in itself to possess any definite form, except in so far as it may be bounded by a shell; but it has the power, wherever it may be exposed, of emitting long thread-like filaments ("pseudopodia"), which interlace with one another to form a network (fig. , b). these filaments can be thrown out at will, and to considerable distances, and can be again retracted into the soft mass of the general body-substance, and they are the agents by which the animal obtains its food. the soft bodies of the _foraminifera_ are protected by a shell, which is usually calcareous, but may be composed of sand-grains cemented together; and it may consist of a single chamber (fig. , a), or of many chambers arranged in different ways (fig. , _b-f_). sometimes the shell has but one large opening into it--the mouth; and then it is from this aperture that the animal protrudes the delicate net of filaments with which it seeks its food. in other cases the entire shell is perforated with minute pores (fig. , e), through which the soft body-substance gains the exterior, covering the whole shell with a gelatinous film of animal matter, from which filaments can be emitted at any point. when the shell consists of many chambers, all of these are placed in direct communication with one another, and the actual substance of the shell is often traversed by minute canals filled with living matter (e.g., in _calcarina_ and _nummulina_). the shell, therefore, may be regarded, in such cases, as a more or less completely porous calcareous structure, filled to its minutest internal recesses with the substance of the living animal, and covered externally with a layer of the same substance, giving off a network of interlacing filaments. [illustration: fig. .--the animal of _nonionina_, one of the _foraminifera_, after the shell has been removed by a weak acid; b, _gromia_, a single-chambered foraminifer (after schultze), showing the shell surrounded by a network of filaments derived from the body substance.] [illustration: fig .--shells of living _foraminifera_. a, _orbulina universa_, in its perfect condition, showing the tubular spines which radiate from the surface of the shell; b, _globigerina bulloides_, in its ordinary condition, the thin hollow spines which are attached to the shell when perfect having been broken off; c, textularia variabilis; d, peneroplis planatus; e, rotalia concamerata; f, _cristellaria subarcuatula._ [fig. a is after wyville thomson; the others are after williamson. all the figures are greatly enlarged.]] such, in brief, is the structure of the living _foraminifera_; and it is believed that in _eozoön_ we have an extinct example of the same group, not only of special interest from its immemorial antiquity, but hardly less striking from its gigantic dimensions. in its original condition, the entire chamber-system of _eozoön_ is believed to have been filled with soft structureless living matter, which passed from chamber to chamber through the wide apertures connecting these cavities, and from tier to tier by means of the tubuli in the shell-wall and the branching canals in the intermediate skeleton. through the perforated shell-wall covering the outer surface the soft body-substance flowed out, forming a gelatinous investment, from every point of which radiated an interlacing net of delicate filaments, providing nourishment for the entire colony. in its present state, as before said, all the cavities originally occupied by the body-substance have been filled with some mineral substance, generally with one of the silicates of magnesia; and it has been asserted that this fact militates strongly against the organic nature of _eozoön_, if not absolutely disproving it. as a matter of fact, however--as previously noticed--it is by no means very uncommon at the present day to find the shells of living species of _foraminifera_ in which all the cavities primitively occupied by the body-substance, down to the minutest pores and canals, have been similarly injected by some analogous silicate, such as glauconite. those, then, whose opinions on such a subject deservedly carry the greatest weight, are decisively of opinion that we are presented in the _eozoön_ of the laurentian rocks of canada with an ancient, colossal, and in some respects abnormal type of the _foraminifera_. in the words of dr carpenter, it is not pretended that "the doctrine of the foraminiferal nature of _eozoön_ can be _proved_ in the demonstrative sense;" but it may be affirmed "that the _convergence of a number of separate and independent probabilities_, all accordant with that hypothesis, while a separate explanation must be invented for each of them on any other hypothesis, gives it that _high probability_ on which we rest in the ordinary affairs of life, in the verdicts of juries, and in the interpretation of geological phenomena generally." it only remains to be added, that whilst _eozoön_ is by far the most important organic body hitherto found in the laurentian, and has been here treated at proportionate length, other traces of life have been detected, which may subsequently prove of great interest and importance. thus, principal dawson has recently described under the name of _archoeosphoerinoe_ certain singular rounded bodies which he has discovered in the laurentian limestones, and which he believes to be casts of the shells of _foraminifera_ possibly somewhat allied to the existing _globigerinoe_. the same eminent palæontologist has also described undoubted worm-burrows from rocks probably of laurentian age. further and more extended researches, we may reasonably hope, will probably bring to light other actual remains of organisms in these ancient deposits. the huronian period. the so-called _huronian rocks_, like the laurentian, have their typical development in canada, and derive their name from the fact that they occupy an extensive area on the borders of lake huron. they are wholly metamorphic, and consist principally of altered sandstones or quartzites, siliceous, felspathic, or talcose slates, conglomerates, and limestones. they are largely developed on the north shore of lake superior, and give rise to a broken and hilly country, very like that occupied by the laurentians, with an abundance of timber, but rarely with sufficient soil of good quality for agricultural purposes. they are, however, largely intersected by mineral veins, containing silver, gold, and other metals, and they will ultimately doubtless yield a rich harvest to the miner. the huronian rocks have been identified, with greater or less certainty, in other parts of north america, and also in the old world. the total thickness of the huronian rocks in canada is estimated as being not less than , feet, but there is considerable doubt as to their precise geological position. in their typical area they rest unconformably on the edges of strata of _lower_ laurentian age; but they have never been seen in direct contact with the _upper_ laurentian, and their exact relations to this series are therefore doubtful. it is thus open to question whether the huronian rocks constitute a distinct formation, to be intercalated in point of time between the laurentian and the cambrian groups; or whether, rather, they should not be considered as the metamorphosed representatives of the lower cambrian rocks of other regions. as regards the fossils of the huronian rocks, little can be said. some of the specimens of _eozoön canadense_ which have been discovered in canada are thought to come from rocks which are probably of huronian age. in bavaria, dr gümbel has described a species of _eozoön_ under the name of _eozoön bavaricum_, from certain metamorphic limestones which he refers to the huronian formation. lastly, the late mr billings described, from rocks in newfoundland apparently referable to the huronian, certain problematical limpet-shaped fossils, to which he gave the name of _aspidella_. literature. amongst the works and memoirs which the student may consult with regard to the laurentian and huronian deposits may be mentioned the following:[ ]-- ( ) 'report of progress of the geological survey of canada from its commencement to ,' pp. - , and pp. - . ( ) 'manual of geology.' dana. d ed. . ( ) 'the dawn of life.' j. w, dawson. . ( ) "on the occurrence of organic remains in the laurentian rocks of canada." sir w. e. logan. 'quart. journ. geol. soc.,' xxi. - .' ( ) "on the structure of certain organic remains in the laurentian limestones of canada." j. w. dawson. 'quart. journ. geol. soc.,' xxi. - . ( ) "additional note on the structure and affinities of eozoön canadense." w. b, carpenter. 'quart. journ. geol. soc.,' xxi. - . ( ) "supplemental notes on the structure and affinities of eozoön' canadense," w. b. carpenter, 'quart. journ. geol. soc.,' xxii. - . ( ) "on the so-called eozoönal rocks." king & rowney. 'quart. journ. geol. soc.,' xxii. - . ( ) 'chemical and geological essays.' sterry hunt. the above list only includes some of the more important memoirs which may be consulted as to the geological and chemical features of the laurentian and huronian rocks, and as to the true nature of _eozoön_. those who are desirous of studying the later phases of the controversy with regard to _eozoön_ must consult the papers of carpenter, carter, dawson, king & rowney, hahn, and others, in the 'quart. journ. of the geological society,' the 'proceedings of the royal irish academy,' the 'annals of natural history,' the 'geological magazine,' &c. dr carpenter's 'introduction to the study of the foraminifera' should also be consulted. [footnote : in this and in all subsequently following bibliographical lists, not only is the selection of works and memoirs quoted necessarily extremely limited; but only such have, as a general rule, been chosen for mention as are easily accessible to students who are in the position of being able to refer to a good library. exceptions, however, are occasionally made to this rule, in favour of memoirs or works of special historical interest. it is also unnecessary to add that it has not been thought requisite to insert in these lists the well-known handbooks of geological and palæontological science; except in such instances as where they contain special information on special points.] chapter viii. the cambrian period. the traces of life in the laurentian period, as we have seen, are but scanty; but the _cambrian rocks_--so called from their occurrence in north wales and its borders ("cambria ")--have yielded numerous remains of animals and some dubious plants. the cambrian deposits have thus a special interest as being the oldest rocks in which occur any number of well-preserved and unquestionable organisms. we have here the remains of the first _fauna_, or assemblage of animals, of which we have at present knowledge. as regards their geographical distribution, the cambrian rocks have been recognised in many parts of the world, but there is some question as to the precise limits of the formation, and we may consider that their most typical area is in south wales, where they have been carefully worked out, chiefly by dr henry hicks. in this region, in the neighbourhood of the promontory of st david's, the cambrian rocks are largely developed, resting upon an ancient ridge of pre-cambrian (laurentian?) strata, and overlaid by the lowest beds of the lower silurian. the subjoined sketch-section (fig. ) exhibits in a general manner the succession of strata in this locality. from this section it will be seen that the cambrian rocks in wales are divided in the first place into a lower and an upper group. the _lower cambrian_ is constituted at the base by a great series of grits, sandstones, conglomerates, and slates, which are known as the "longmynd group," from their vast development in the longmynd hills in shropshire, and which attain in north wales a thickness of feet or more. the longmynd beds are succeeded by the so-called "menevian group," a series of sandstones, flags, and grits, about feet in thickness, and containing a considerable number of fossils. the _upper cambrian_ series consists in its lower portion of nearly feet of strata, principally shaly and slaty, which are known as the "lingula flags," from the great abundance in them of a shell referable to the genus _lingula_. these are followed by feet of dark shales and flaggy sandstones, which are known as the "tremadoc slates," from their occurrence near tremadoc in north wales; and these in turn are surmounted, apparently quite conformably, by the basement beds of the lower silurian. [illustration: fig . generalized section of the cambrian rocks in wales.] the above may be regarded as giving a typical series of the cambrian rocks in a typical locality; but strata of cambrian age are known in many other regions, of which it is only possible here to allude to a few of the most important. in scandinavia occurs a well-developed series of cambrian deposits, representing both the lower and upper parts of the formation. in bohemia, the upper cambrian, in particular, is largely developed, and constitutes the so-called "primordial zone" of barrande. lastly, in north america, whilst the lower cambrian is only imperfectly developed, or is represented by the huronian, the upper cambrian formation has a wide extension, containing fossils similar in character to the analogous strata in europe, and known as the "potsdam sandstone." the subjoined table shows the chief areas where cambrian rocks are developed, and their general equivalency: tabular view of the cambrian formation. _britain._ | _europe._ | _america._ | | /a. tremadoc slates. | a. primordial zone | a. potsdam | | of bohemia. | sandstone. | b. lingula flags. | b. paradoxides | b. acadian upper < | schists, olenus | group of new cambrian. | | schists, and | brunswick. | | dictyonema schists | \ | of sweden. | | | /a. longmynd beds. | a. fucoidal | huronian | | sandstone of sweden | formation? | b. llanberis slates.| b. _eophyton_ | | | sandstone of sweden.| lower < c. harlech grits. | | cambrian. | d. _oldhamia_ | | | slates of ireland.| | | e. conglomerates and| | | and sandstones of | | | sutherlandshire? | | \f. menevian beds. | | like all the older palæozoic deposits, the cambrian rocks, though by no means necessarily what would be called actually "metamorphic," have been highly cleaved, and otherwise altered from their original condition. owing partly to their indurated state, and partly to their great antiquity, they are usually found in the heart of mountainous districts, which have undergone great disturbance, and have been subjected to an enormous amount of denudation. in some cases, as in the longmynd hills in shropshire, they form low rounded elevations, largely covered by pasture, and with few or no elements of sublimity. in other cases, however, they rise into bold and rugged mountains, girded by precipitous cliffs. industrially, the cambrian rocks are of interest, if only for the reason that the celebrated welsh slates of llanberis are derived from highly-cleaved beds of this age. taken as a whole, the cambrian formation is essentially composed of arenaceous and muddy sediments, the latter being sometimes red, but more commonly nearly black in colour. it has often been supposed that the cambrians are a deep-sea deposit, and that we may thus account for the few fossils contained in them; but the paucity of fossils is to a large extent imaginary, and some of the lower cambrian beds of the longmynd hills would appear to have been laid down in shallow water; as they exhibit rain-prints, sun-cracks, and ripple-marks--incontrovertible evidence of their having been a shore-deposit. the occurrence, of innumerable worm-tracks and burrows in many cambrian strata is also a proof of shallow-water conditions; and the general absence of limestones, coupled with the coarse mechanical nature of many of the sediments of the lower cambrian, maybe taken as pointing in the same direction. the _life_ of the cambrian, though not so rich as in the succeeding silurian period, nevertheless consists of representatives of most of the great classes of invertebrate animals. the coarse sandy deposits of the formation, which abound more particularly towards its lower part, naturally are to a large extent barren of fossils; but the muddy sediments, when not too highly cleaved, and especially towards the summit of the group, are replete with organic remains. this is also the case, in many localities at any rate, with the finer beds of the potsdam sandstone in america. limestones are known to occur in only a few areas (chiefly in america), and this may account for the apparent total absence of corals. it is, however, interesting to note that, with this exception, almost all the other leading groups of invertebrates are known to have come into existence during the cambrian period. fig. .--fragment of _eophyton linneanum_, a supposed land-plant. lower cambrian, sweden, of the natural size. of the land-surfaces of the cambrian period we know nothing; and there is, therefore, nothing surprising in the fact that our acquaintance with the cambrian vegetation is confined to some marine plants or sea-weeds, often of a very obscure and problematical nature. the "fucoidal sandstone" of sweden, and the "potsdam sandstone" of north america, have both yielded numerous remains which have been regarded as markings left by sea-weeds or "fucoids;" but these are highly enigmatical in their characters, and would, in many instances, seem to be rather referable to the tracks and burrows of marine worms. the first-mentioned of these formations has also yielded the curious, furrowed and striated stems which have been described as a kind of land-plant under the name of _eopkyton_ (fig. ). it cannot be said, however, that the vegetable origin of these singular bodies has been satisfactorily proved. lastly, there are found in certain green and purple beds of lower cambrian age at bray head, wicklow, ireland, some very remarkable fossils, which are well known under the name of _oldhamia_, but the true nature of which is very doubtful. the commonest form of _oldhamia_ (fig. ) consists of a thread-like stem or axis, from which spring at regular intervals bundles of short filamentous branches in a fan-like manner. in the locality where it occurs, the fronds of _oldhamia_ are very abundant, and are spread over the surfaces of the strata in tangled layers. that it is organic is certain, and that it is a calcareous sea-weed is probable; but it may possibly belong to the sea-mosses (_polyzoa_), or to the sea-firs (_sertularians_). amongst the lower forms of animal life (_protozoa_), we find the sponges represented by the curious bodies, composed of netted fibres, to which the name of _protospongia_ has been given (fig. , a); and the comparatively gigantic, conical, or cylindrical fossils termed _archoeocyathus_ by mr billings are certainly referable either to the _foraminifera_ or to the sponges. the almost total absence of limestones in the formation may be regarded as a sufficient explanation of the fact that the _foraminifera_ are not more largely and unequivocally represented; though the existence of greensands in the cambrian beds of wisconsin and tennessee may be taken as an indication that this class of animals was by no means wholly wanting. the same fact may explain the total absence of corals, so far as at present known. [illustration: fig. .--a portion of _oldhamia antiqua_, lower cambrian, wicklow, ireland, of the natural size. (after salter.)] the group of the _echinodermata_ (sea-lilies, sea-urchins, and their allies) is represented by a few forms, which are principally of interest as being the earliest-known examples of the class. it is also worthy of note that these precursors of a group which subsequently attains such geological importance, are referable to no less than three distinct _orders_--the crinoids or sea-lilies, represented by a species of _dendrocrinus_; the cystideans by _protocystites_; and the star-fishes by _palasterina_ and some other forms. only the last of these groups, however, appears to occur in the lower cambrian. [illustration: fig. .--annelide-burrows (_scolithus linearus_) from the potsdam sandstone of canada, of the natural size. (after billings.)] the ringed-worms (_annelida_), if rightly credited with all the remains usually referred to them, appear to have swarmed in the cambrian seas. being soft-bodied, we do not find the actual worms themselves in the fossil condition, but we have, nevertheless, abundant traces of their existence. in some cases we find vertical burrows of greater or less depth, often expanded towards their apertures, in which the worm must have actually lived (fig. ), as various species do at the present day. in these cases, the tube must have been rendered more or less permanent by receiving a coating of mucus, or perhaps a genuine membranous secretion, from the body of the animal; and it may be found quite empty, or occupied by a cast of sand or mud. of this nature are the burrows which have been described under the names of _scolithus_ and _scolecoderma_, and probably the _histioderma_ of the lower cambrian of ireland. in other cases, as in _arenicolites_ (fig. , b), the worm seems to have inhabited a double burrow, shaped like the letter u, and having two openings placed close together on the surface of the stratum. thousands of these twin-burrows occur in some of the strata of the longmynd, and it is supposed that the worm used one opening to the burrow as an aperture of entrance, and the other as one of exit. in other cases, again, we find simply the meandering trails caused by the worm dragging its body over the surface of the mud. markings of this kind are commoner in the silurian rocks, and it is generally more or less doubtful whether they may not have been caused by other marine animals, such as shellfish, whilst some of them have certainly nothing whatever to do with the worms. lastly, the cambrian beds often show twining cylindrical bodies, commonly more or less matted together, and not confined to the surfaces of the strata, but passing through them. these have often been regarded as the remains of sea-weeds, but it is more probable that they represent casts of the underground burrows of worms of similar habits to the common lob-worm (_arenicola_) of the present day. the _articulate_ animals are numerously represented in the cambrian deposits, but exclusively by the class of _crustaceans_. some of these are little double-shelled creatures, resembling our living water-fleas (_ostracoda_). a few are larger forms, and belong to the same group as the existing brine-shrimps and fairy-shrimps (_phyllopoda_). one of the most characteristic of these is the _hymenocaris vermicauda_ of the lingula flags (fig. , d). by far the larger number of the cambrian _crustacea_ belong, however, to the remarkable and wholly extinct group of the _trilobites_. these extraordinary animals must have literally swarmed in the seas of the later portion of this and the whole of the succeeding period; and they survived in greatly diminished numbers till the earlier portion of the carboniferous period. they died out, however, wholly before the close of the palæozoic epoch, and we have no crustaceans at the present day which can be considered as their direct representatives. they have, however, relationships of a more or less intimate character with the existing groups of the phyllopods, the king-crabs (_limulus_), and the isopods ("slaters," wood-lice, &c.) indeed, one member of the last-mentioned order, namely, the _serolis_ of the coasts of patagonia, has been regarded as the nearest living ally of the trilobites. be this as it may, the trilobites possessed a skeleton which, though capable of undergoing almost endless variations, was wonderfully constant in its pattern of structure, and we may briefly describe here the chief features of this. [illustration: fig. .--cambrian trilobites: a, _paradoxides bohemicus_, reduced in size; b, _ellipsocephalus hoffi_; c, _sao hirsuta_; d, _conocorypke sultzeri_ (all the above, together with fig. g, are from the upper cambrian or "primordial zone" of bohemia); e, head-shield of _dikellocephalus celticus_, from the lingula flags of wales; f, head-shield of _conocoryphe matthewi_, from the upper cambrian (acadian group) of new brunswick; g, _agnostus rex_, bohemia; h, tail-shield of _dikellocephalus minnesotensis_, from the upper cambrian (potsdam sandstone) of minnesota. (after barrande, dawson, salter, and dale owen.)] the upper surface of the body of a trilobite was defended by a strong shell or "crust," partly horny and partly calcareous in its composition. this shell (fig. ) generally exhibits a very distinct "trilobation" or division into three longitudinal lobes, one central and two lateral. it also exhibits a more important and more fundamental division into three transverse portions, which are so loosely connected with one another as very commonly to be found separate. the first and most anterior of these divisions is a shield or buckler which covers the head; the second or middle portion is composed of movable rings covering the trunk ("thorax "); and the third is a shield which covers the tailor "abdomen." the head-shield (fig. , e) is generally more or less semicircular in shape; and its central portion, covering the stomach of the animal, is usually strongly elevated, and generally marked by lateral furrows. a little on each side of the head are placed the eyes, which are generally crescentic in shape, and resemble the eyes of insects and many existing crustaceans in being "compound," or made up of numerous simple eyes aggregated together. so excellent is the state of preservation of many specimens of trilobites, that the numerous individual lenses of the eyes have been uninjured, and as many as four hundred have been counted in each eye of some forms. the eyes may be supported upon prominences, but they are never carried on movable stalks (as they are in the existing lobsters and crabs); and in some of the cambrian trilobites, such as the little _agnosti_ (fig. g), the animal was blind. the lateral portions of the head-shield are usually separated from the central portion by a peculiar line of division (the so-called "facial suture") on each side; but this is also wanting in some of the cambrian species. the backward angles of the head-shield, also, are often prolonged into spines, which sometimes reach a great length. following the head-shield behind, we have a portion of the body which is composed of movable segments or "body-rings," and which is technically called the "thorax," ordinarily, this region is strongly trilobed, and each ring consists of a central convex portion, and of two flatter side-lobes. the number of body-rings in the thorax is very variable (from two to twenty-six), but is fixed for the adult forms of each group of the trilobites. the young forms have much fewer rings than the full-grown ones; and it is curious to find that the cambrian trilobites very commonly have either a great many rings (as in _paradoxides_, fig. , a), or else very few (as in _agnostus_, fig. , g). in some instances, the body-rings do not seem to have been so constructed as to allow of much movement, but in other cases this region of the body is so flexible that the animal possessed the power of rolling itself up completely, like a hedgehog; and many individuals have been permanently preserved as fossils in this defensive condition. finally, the body of the trilobite was completed by a tail-shield (technically termed the "pygidium"), which varies much in size and form, and is composed of a greater or less number of rings, similar to those which form the thorax, but immovably amalgamated with one another (fig. , h). the under surface of the body in the trilobites appears to have been more or less entirely destitute of hard structures, with the exception of a well-developed upper lip, in the form of a plate attached to the inferior side of the head-shield in front. there is no reason to doubt that the animal possessed legs; but these structures seem to have resembled those of many living crustaceans in being quite soft and membranous. this, at any rate, seems to have been generally the case; though structures which have been regarded as legs have been detected on the under surface of one of the larger species of trilobites. there is also, at present, no direct evidence that the trilobites possessed the two pairs of jointed feelers ("antennæ") which are so characteristic of recent crustaceans. the trilobites vary much in size, and the cambrian formation presents examples of both the largest and the smallest members of the order. some of the young forms may be little bigger than a millet-seed, and some adult examples of the smaller species (such as _agnostus_) may be only a few lines in length; whilst such giants of the order as _paradoxides_ and _asaphus_ may reach a length of from one to two feet. judging from what we actually know as to the structure of the trilobites, and also from analogous recent forms, it would seem that these ancient crustaceans were mud-haunting creatures, denizens of shallow seas, and affecting the soft silt of the bottom rather than the clear water above. whenever muddy sediments are found in the cambrian and silurian formations, there we are tolerably sure to find trilobites, though they are by no means absolutely wanting in limestones. they appear to have crawled out upon the sea-bottom, or burrowed in the yielding mud, with the soft under surface directed downwards; and it is probable that they really derived their nutriment from the organic matter contained in the ooze amongst which they lived. the vital organs seem to have occupied the central lobe of the skeleton, by which they were protected; and a series of delicate leaf-like paddles, which probably served as respiratory organs, would appear to have been carried on the under surface of the thorax. that they had their enemies may be regarded as certain; but we have no evidence that they were furnished with any offensive weapons, or, indeed, with any means of defence beyond their hard crust, and the power, possessed by so many of them, of rolling themselves into a ball. an additional proof of the fact that they for the most part crawled along the sea-bottom is found in the occurrence of tracks and markings of various kinds, which can hardly be ascribed to any other creatures with any show of probability. that this is the true nature of some of the markings in question cannot be doubted at all; and in other cases no explanation so probable has yet been suggested. if, however, the tracks which have been described from the potsdam sandstone of north america under the name of _protichnites_ are really due to the peregrinations of some trilobite, they must have been produced by one of the largest examples of the order. as already said, the cambrian rocks are very rich in the remains of trilobites. in the lowest beds of the series (longmynd rocks), representatives of some half-dozen genera have now been detected, including the dwarf _agnostus_ and the giant _paradoxides_. in the higher beds, the number both of genera and species is largely increased; and from the great comparative abundance of individuals, the trilobites have every right to be considered as the most characteristic fossils of the cambrian period,--the more so as the cambrian species belong to peculiar types, which, for the most part, died out before the commencement of the silurian epoch. all the remaining cambrian fossils which demand any notice here are members of one or other division of the great class of the _mollusca_, or "shell-fish" properly so called. in the lower cambrian rocks the lamp-shells (_brachiopoda_) are the principal or sole representatives of the class, and appear chiefly in three interesting and important types--namely, _lingulella, discina,_ and _obolella_. of these the last (fig. , i) is highly characteristic of these ancient deposits; whilst _discina_ is one of those remarkable persistent types which, commencing at this early period, has continued to be represented by varying forms through all the intervening geological formations up to the present day. _lingulella_ (fig. , c), again, is closely allied to the existing "goose-bill" lamp-shell (_lingula anatina_), and thus presents us with another example of an extremely long-lived type. the _lingulelloe_ and their successors; the _linguloe_, are singular in possessing a shell which is of a horny texture, and contains but a small proportion of calcareous matter. in the upper cambrian rocks, the _lingulelloe_ become much more abundant, the broad satchel-shaped species known as _l. davisii_ (fig. , e) being so abundant that one of the great divisions of the cambrian is termed the "lingula flags." here, also, we meet for the first time with examples of the genus orthis (fig. , f, k, l) a characteristic palæozoic type of the brachiopods, which is destined to undergo a vast extension in later ages. [illustration: fig .--cambrian fossils: a, _protospongia fenestrata_, menevian group; b, _arenicolites didymus_, longmynd group; c, _lingulella ferruginea_, longmynd and menevian, enlarged; d, _hymenocaris vermicauda_, lingula flags; e, _lingulella davisii_, lingula flags; f, _orthis lenticularis_, lingula flags; g, _theca davidii_, tremadoc slates; h, _modiolopsis solvensis_, tremadoc slates; i, _obolela sagittalis_, interior of valve, menevian; j, exterior of the same; k, _orthis hicksii_, menevian; l, cast of the same; m, _olenus micrurus_, lingula flags. (alter salter, hicks, and davidson.)] of the higher groups of the _mollusca_ the record is as yet but scanty. in the lower cambrian, we have but the thin, fragile, dagger-shaped shells of the free-swimming oceanic molluscs or "winged-snails" (_pteropoda_), of which the most characteristic is the genus _theca_ (fig. , g). in the upper cambrian, in addition to these, we have a few univalves (_gasteropoda_), and, thanks to the researches of dr hicks, quite a small assemblage of bivalves (_lamellibranchiata_), though these are mostly of no great dimensions (fig. , h). of the chambered _cephalopoda_ (cuttle-fishes and their allies), we have but few traces; and these wholly confined to the higher beds of the formation. we meet, however, with examples of the wonderful genus _orthoceras_, with its straight, partitioned shell, which we shall find in an immense variety of forms in the silurian rocks. lastly, it is worthy of note that the lowest of all the groups of the _mollusca_--namely, that of the sea-mats, sea-mosses, and lace-corals (_polyzoa_)--is only doubtfully known to have any representatives in the cambrian, though undergoing a large and varied development in the silurian deposits. [illustration: fig. .--fragment of _dictyonema sociale_, considerably enlarged, showing the horny branches, with their connecting cross-bars, and with a row of cells on each side. (original.)] an exception, however, may with much probability be made to this statement in favour of the singular genus _dictyonema_ (fig. ), which is highly characteristic of the highest cambrian beds (tremadoc slates). this curious fossil occurs in the form of fan-like or funnel-shaped expansions, composed of slightly-diverging horny branches, which are united in a net-like manner by numerous delicate cross-bars, and exhibit a row of little cups or cells, in which the animals were contained, on each side. _dictyonema_ has generally been referred to the _graptolites_; but it has a much greater affinity with the plant-like sea-firs (_sertularians_) or the sea-mosses (_polyzoa_), and the balance of evidence is perhaps in favour of placing it with the latter. literature. the following are the more important and accessible works and memoirs which may be consulted in studying the stratigraphical and palæontological relations of the cambrian rocks:-- ( ) 'siluria.' sir roderick murchison. th ed., pp. - . ( ) 'synopsis of the classification of the british palæozoic rocks.' sedgwick. introduction to the d fasciculus of the 'descriptions of british palæozoic fossils in the woodwardian museum,' by f. m'coy, pp. i-xcviii, . ( ) 'catalogue of the cambrian and silurian fossils in the geological museum of the university of cambridge.' salter. with a preface by prof. sedgwick. . ( ) 'thesaurus siluricus.' bigsby. . ( ) "history of the names cambrian and silurian." sterry hunt.--'geological magazine.' . ( ) 'système silurien du centre de la bohême.' barrande. vol. i. ( ) 'report of progress of the geological survey of canada, from its commencement to ,' pp. - . ( ) 'acadian geology.' dawson. pp. - . ( ) "guide to the geology of new york," lincklaen; and "contributions to the palæontology of new york," james hall.--'fourteenth report on the state cabinet.' . ( ) 'palæozoic fossils of canada.' billings. . ( ) 'manual of geology.' dana. pp. - . d ed. . ( ) "geology of north wales," ramsay; with appendix on the fossils, salter.--'memoirs of the geological survey of great britain,' vol. iii. . ( ) "on the ancient rocks of the st david's promontory, south wales, and their fossil contents." harkness and hicks.--' quart. journ. geol. soc.,' xxvii. - . . ( ) "on the tremadoc rocks in the neighbourhood of st david's, south wales, and their fossil contents." hicks.--'quart. journ. geol. soc.,' xxix. - . . in the above list, allusion has necessarily been omitted to numerous works and memoirs on the cambrian deposits of sweden and norway, central europe, russia, spain, and various parts of north america, as well as to a number of important papers on the british cambrian strata by various well-known observers. amongst these latter may be mentioned memoirs by prof. phillips, and messrs salter, hicks, belt, plant, homfray, ash, holl, &c. chapter ix. the lower silurian period. the great system of deposits to which sir roderick murchison applied the name of "silurian rocks" reposes directly upon the highest cambrian beds, apparently without any marked unconformity, though with a considerable change in the nature of the fossils. the name "silurian" was originally proposed by the eminent geologist just alluded to for a great series of strata lying below the old red sandstone, and occupying districts in wales and its borders which were at one time inhabited by the "silures," a tribe of ancient britons. deposits of a corresponding age are now known to be largely developed in other parts of england, in scotland, and in ireland, in north america, in australia, in india, in bohemia, saxony, bavaria, russia, sweden and norway, spain, and in various other regions of less note. in some regions, as in the neighbourhood of st petersburg, the silurian strata are found not only to have preserved their original horizontality, but also to have retained almost unaltered their primitive soft and incoherent nature. in other regions, as in scandinavia and many parts of north america, similar strata, now consolidated into shales, sandstones, and limestones, may be found resting with a very slight inclination on still older sediments. in a great many regions, however, the silurian deposits are found to have undergone more or less folding, crumpling, and dislocation, accompanied by induration and "cleavage" of the finer and softer sediments; whilst in some regions, as in the highlands of scotland, actual "metamorphism" has taken place. in consequence of the above, silurian districts usually present the bold, rugged, and picturesque outlines which are characteristic of the older "primitive" rocks of the earth's crust in general. in many instances, we find silurian strata rising into mountain-chains of great grandeur and sublimity, exhibiting the utmost diversity of which rock-scenery is capable, and delighting the artist with endless changes of valley, lake, and cliff. such districts are little suitable for agriculture, though this is often compensated for by the valuable mineral products contained in the rocks. on the other hand, when the rocks are tolerably soft and uniform in their nature, or when few disturbances of the crust of the earth have taken place, we may find silurian areas to be covered with an abundant pasturage or to be heavily timbered. under the head of "silurian rocks," sir roderick murchison included all the strata between the summit of the "longmynd." beds and the old red sandstone, and he divided these into the two great groups of the _lower_ silurian and _upper_ silurian. it is, however, now generally admitted that a considerable portion of the basement beds of murchison's silurian series must be transferred---if only upon palæontological grounds--to the upper cambrian, as has here been done; and much controversy has been carried on as to the proper nomenclature of the upper silurian and of the remaining portion of murchison's lower silurian. thus, some would confine the name "silurian" exclusively to the upper silurian, and would apply the name of "cambro-silurian" to the lower silurian, or would include all beds of the latter age in the "cambrian" series of sedgwick. it is not necessary to enter into the merits of these conflicting views. for our present purpose, it is sufficient to recognise that there exist two great groups of rocks between the highest cambrian beds, as here defined, and the base of the devonian or old red sandstone. these two great groups are so closely allied to one another, both physically and palæontologically, that many authorities have established a third or intermediate group (the "middle silurian"), by which a passage is made from one into the other. this method of procedure involves disadvantages which appear to outweigh its advantages; and the two groups in question are not only generally capable of very distinct stratigraphical separation, but at the same time exhibit, together with the alliances above spoken of, so many and such important palæontological differences, that it is best to consider them separately. we shall therefore follow this course in the present instance; and pending the final solution of the controversy as to cambrian and silurian nomenclature, we shall distinguish these two groups of strata as the "lower silurian" and the "upper silurian." the _lower silurian rocks_ are known already to be developed in various regions; and though their _general_ succession in these areas is approximately the same, each area exhibits peculiarities of its own, whilst the subdivisions of each are known by special names. all, therefore, that can be attempted here, is to select two typical areas--such as wales and north america and to briefly consider the grouping and divisions of the lower silurian in each. in wales, the line between the cambrian and lower silurian is somewhat ill-defined, and is certainly not marked by any strong unconformity. there are, however; grounds for accepting the line proposed, for palæontological reasons, by dr hicks, in accordance with which the tremadoc slates ("lower tremadoc" of salter) become the highest of the cambrian deposits of britain. if we take this view, the lower silurian rocks of wales and adjoining districts are found to have the following _general_ succession from below upwards (fig. ):-- . the _arenig group_.--this group derives its name from the arenig mountains, where it is extensively developed. it consists of about feet of slates, shales, and flags, and is divisible into a lower, middle, and upper division, of which the former is often regarded as cambrian under the name of "upper tremadoc slates." . the _llandeilo group_.--the thickness of this group varies from about to as much as , feet; but in this latter case a great amount of the thickness is made up of volcanic ashes and interbedded traps. the sedimentary beds of this group are principally slates and flags, the latter occasionally with calcareous bands; and the whole series can be divided into a lower, middle, and upper llandeilo division, of which the last is the most important. the name of "llandeilo" is derived from the town of the same name in wales, where strata of this age were described by murchison. . the _caradoc_ or _bala group_.--the alternative names of this group are also of local origin, and are derived, the one from caer caradoc in shropshire, the other from bala in wales, strata of this age occurring in both localities. the series is divided into a lower and upper group, the latter chiefly composed of shales and flags, and the former of sandstones and shales, together with the important and interesting calcareous band known as the "bala limestone." the thickness of the entire series varies from to as much as , feet, according as it contains more or less of interstratified igneous rocks. . the _llandovery group_ (lower llandovery of murchison).--this series, as developed near the town of llandovery, in caermarthenshire, consists of less than feet of conglomerates, sandstones, and shales. it is probable, however, that the little calcareous band known as the "hirnant limestone," together with certain pale-coloured slates which lie above the bala limestone, though usually referred to the caradoc series, should in reality be regarded as belonging to the llandovery group. the general succession of the lower silurian strata of wales and its borders, attaining a maximum thickness (along with contemporaneous igneous matter) of nearly , feet, is diagramatically represented in the annexed sketch-section (fig. ):-- [illustration: fig . generalized section of the lower silurian rocks of wales.] in north america, both in the united states and in canada, the silurian rocks are very largely developed, and may be regarded as constituting an exceedingly full and typical series of the deposits of this period. the chief groups of the silurian rocks of north america are as follows, beginning, as before, with the lowest strata, and proceeding upwards (fig. ):-- . _quebec group_.--this group is typically developed in the vicinity of quebec, where it consists of about feet of strata, chiefly variously-coloured shales, together with some sandstones and a few calcareous bands. it contains a number of peculiar graptolites, by which it can be identified without question with the arenig group of wales and the corresponding skiddaw slates of the north of england. it is also to be noted that numerous trilobites of a distinct cambrian _facies_ have been obtained in the limestones of the quebec group, near quebec. these fossils, however, have been exclusively obtained from the limestones of the group; and as these limestones are principally calcareous breccias or conglomerates, there is room for believing that these primordial fossils are really derived, in part at any rate, from fragments of an upper cambrian limestone. in the state of new york, the graptolitic shales of quebec are wanting; and the base of the silurian is constituted by the so-called "calciferous sand-rock" and "chazy limestone."[ ] the first of these is essentially and typically calcareous, and the second is a genuine limestone. [footnote : the precise relations of the quebec shales with graptolites (levis formation) to the calciferous and chazy beds are still obscure, though there seems little doubt but that the quebec shales are superior to the calciferous sand-rock.] . the _trenton group_.--this is an essentially calcareous group, the various limestones of which it is composed being known as the "bird's-eye," "black river," and "trenton" limestones, of which the last is the thickest and most important. the thickness of this group is variable, and the bands of limestone in it are often separated by beds of shale. . the _cincinnati group_ (hudson river formation[ ]).--this group consists essentially of a lower series of shales, often black in colour and highly charged with bituminous matter (the "utica slates "), and of an upper series of shales, sandstones, and limestones (the "cincinnati" rocks proper). the exact parallelism of the trenton and cincinnati groups with the subdivisions of the welsh silurian series can hardly be stated positively. probably no precise equivalency exists; but there can be no doubt but that the trenton and cincinnati groups correspond, as a whole, with the llandeilo and caradoc groups of britain. the subjoined diagrammatic section (fig. ) gives a general idea of the succession of the lower silurian rocks of north america:-- [illustration: fig . generalized section of the lower silurian rocks of north america.] [illustration: fig. .--_licrophycus ottawaensis_ a "fucoid," from the trenton limestone (lower silurian) of canada. (after billings.)] [footnote : there is some difficulty about the precise nomenclature of this group. it was originally called the "hudson river formation;" but this name is inappropriate, as rocks of this age hardly touch anywhere the actual hudson river itself, the rocks so called formerly being now known to be of more ancient date. there is also some want of propriety in the name of "cincinnati group," since the rocks which are known under this name in the vicinity of cincinnati itself are the representatives of the trenton limestone, utica slates, and the old hudson river group, inseparably united in what used to be called the "blue limestone series."]. of the _life_ of the lower silurian period we have record in a vast number of fossils, showing that the seas of this period were abundantly furnished with living denizens. we have, however, in the meanwhile, no knowledge of the land-surfaces of the period. we have therefore no means of speculating as to the nature of the terrestrial animals of this ancient age, nor is anything known with certainty of any land-plants which may have existed. the only relics of vegetation upon which a positive opinion can be expressed belong to the obscure group of the "fucoids," and are supposed to be the remains of sea-weeds. some of the fossils usually placed under this head are probably not of a vegetable nature at all, but others (fig. ) appear to be unquestionable plants. the true affinities of these, however, are extremely dubious. all that can be said is, that remains which appear to be certainly vegetable, and which are most probably due to marine plants, have been recognised nearly at the base of the lower silurian (arenig), and that they are found throughout the series whenever suitable conditions recur. the protozoans appear to have flourished extensively in the lower silurian seas, though to a large extent under forms which are still little understood. we have here for the first time the appearance of foraminifera of the ordinary type--one of the most interesting observations in this collection being that made by ehrenberg, who showed that the lower silurian sandstones of the neighbourhood of st petersburg contained casts in glauconite of foraminiferous shells, some of which are referable to the existing genera _rotalia_ and _texularia_. true _sponges_, belonging to that section of the group in which the skeleton is calcareous, are also not unknown, one of the most characteristic genera being _astylospongia_ (fig. ). in this genus are included more or less globular, often lobed sponges, which are believed not to have been attached to foreign bodies. in the form here figured there is a funnel-shaped cavity at the summit; and the entire mass of the sponge is perforated, as in living examples, by a system of canals which convey the sea-water to all parts of the organism. the canals by which the sea-water gains entrance open on the exterior of the sphere, and those by which it again escapes from the sponge open into the cup-shaped depression at the summit. [illustration: fig. .--_astylospongia proemorsa_, cut vertically so as to exhibit the canal-system in the interior. lower silurian, tennessee. (after ferdinand roemer.)] the most abundant, and at the same time the least understood, of lower silurian protozoans belong, however, to the genera _stromatopora_ and _receptaculites_, the structure of which can merely be alluded to here. the specimens of _stromatopora_ (fig. ) occur as hemispherical, pear-shaped, globular, or irregular masses, often of very considerable size, and sometimes demonstrably attached to foreign bodies. in their structure these masses consist of numerous thin calcareous laminæ, usually arranged concentrically, and separated by narrow interspaces. these interspaces are generally crossed by numerous vertical calcareous pillars, giving the vertical section of the fossil a lattice-like appearance. there are also usually minute pores in the concentric laminæ, by which the successive interspaces are placed in communication; and sometimes the surface presents large rounded openings, which appear to correspond with the water-canals of the sponges. upon the whole, though presenting some curious affinities to the calcareous sponges, _stromatopora_ is perhaps more properly regarded as a gigantic _foraminifer_. if this view be correct, it is of special interest as being probably the nearest ally of _eozoön_, the general appearance of the two being strikingly similar, though their minute structure is not at all the same. lastly, in the fossils known as _receptaculites_ and _ischadites_ we are also presented with certain singular lower silurian protozoans, which may with great probability be regarded as gigantic _foraminifera_. their structure is very complex; but fragments are easily recognised by the fact that the exterior is covered with numerous rhomboidal calcareous plates, closely fitting together, and arranged in peculiar intersecting curves, presenting very much the appearance of the engine-turned case of a watch. [illustration: fig. .--a small and perfect specimen of _stromatopora rugosa_, of the natural size, from the trenton limestone of canada. (after billings.)] passing next to the sub-kingdom of _coelenterate_ animals (zoophytes, corals, &c.), we find that this great group, almost or wholly absent in the cambrian, is represented in lower silurian deposits by a great number of forms belonging on the one hand to the true corals, and en the other hand to the singular family of the _graptolites_. if we except certain plant-like fossils which probably belong rather to the sertularians or the polyzoans (e.g., _dictyonema, dendrograptus_, &c.), the family of the _graptolites_ may be regarded as exclusively silurian in its distribution. not only is this the case, but it attained its maximum development almost upon its first appearance, in the arenig rocks; and whilst represented by a great variety of types in the lower silurian; it only exists in the upper silurian in a much diminished form. the _graptolites_ (gr. _grapho_, i write; _lithos_, stone) were so named by linnæus, from the resemblance of some of them to written or pencilled marks upon the stone, though the great naturalist himself did not believe them to be true fossils at all. they occur as linear or leaf-like bodies, sometimes simple, sometimes compound and branched; and no doubt whatever can be entertained as to their being the skeletons of composite organisms, or colonies of semi-independent animals united together by a common fleshy trunk, similar to what is observed in the colonies of the existing sea-firs (sertularians). this fleshy trunk or common stem of the colony was protected by a delicate horny sheath, and it gave origin to the little flower-like "polypites," which constituted the active element of the whole assemblage. these semi-independent beings were, in turn, protected each by a little horny cup or cell, directly connected with the common sheath below, and terminating above in an opening through which the polypite could protrude its tentacled head or could again withdraw itself for safety. the entire skeleton, again, was usually, if not universally, supported by a delicate horny rod or "axis," which appears to have been hollow, and which often protrudes to a greater or less extent beyond one or both of the extremities of the actual colony. the above gives the elementary constitution of any _graptolite_, but there are considerable differences as to the manner in which these elements are arranged and combined. in some forms the common stem of the colony gives origin to but a single row of cells on one side. if the common stem is a simple, straight, or slightly-curved linear body, then we have the simplest form of graptolite known (the genus _monograptus_); and it is worthy of note that these simple types do not come into existence till comparatively late (llandeilo), and last nearly to the very close of the upper silurian. in other cases, whilst there is still but a single row of cells, the colony may consist of two of these simple stems springing from a common point, as in the so-called "twin graptolites" (_didymograptus_, fig. ). this type is entirely confined to the earlier portion of the lower silurian period (arenig and llandeilo). in other cases, again, there may be four of such stems springing from a central point (_tetragraptus_). lastly, there are numerous complex forms (such as _dichograptus, loganograptus_, &c.) in which there are eight or more of these simple branches, all arising from a common centre (fig. ), which is sometimes furnished with a singular horny disc. these complicated branching forms, as well as the _tetragrapti_, are characteristic of the horizon of the arenig group. similar forms, often specifically identical, are found at this horizon in wales, in the great series of the skiddaw slates of the north of england, in the quebec group in canada, in equivalent beds in sweden, and in certain gold-bearing slates of the same age in victoria in australia. [illustration: fig. .--_dichograptus octobrachiatus_, a branched, "unicellular" graptolite from the skiddaw and quebec groups (arenig). (after hall.)] in another great group of graptolites (including the genera _diplograptus, dicranograptus, climacograptus_, &c.) the common stem of the colony gives origin, over part or the whole or its length, to _two_ rows of cells, one on each side (fig. ). these "double-celled" graptolites are highly characteristic of the lower silurian deposits; and, with an exception more apparent than real in bohemia, they are exclusively confined to strata of lower silurian age, and are not known to occur in the upper silurian. lastly, there is a group of graptolites (_phyllograptus_, fig. ) in which the colony is leaf-like in form, and is composed of _four_ rows of cells springing in a cross-like manner from the common stem. these forms are highly characteristic of the arenig group. [illustration: fig. .--central portion of the colony of _didymegraptus divaricatus_, upper llandeilo, dumfresshire. (original.)] [illustration: fig. .--examples of _diplograptus pristis_, showing variations in the appendages at the base. upper llandeilo, dumfriesshire. (original.)] [illustration: fig. .--group of individuals of _phyllograptus typus_, from the quebec group of canada. (after hall.) one of the four rows of cells is hidden on the under surface.] the graptolites are usually found in dark-coloured, often black shales, which sometimes contain so much carbon as to become "anthracitic." they may be simply carbonaceous; but they are more commonly converted into iron-pyrites, when they glitter with the brilliant lustre of silver as they lie scattered on the surface of the rock, fully deserving in their metallic tracery the name of "written stones." they constitute one of the most important groups of silurian fossils, and are of the greatest value in determining the precise stratigraphical position of the beds in which they occur. they present, however, special difficulties in their study; and it is still a moot point as to their precise position in the zoological scale. the balance of evidence is in favour of regarding them as an ancient and peculiar group of the sea-firs (hydroid zoophytes), but some regard them as belonging rather to the sea-mosses (_polyzoa_). under any circumstances, they cannot be directly compared either with the ordinary sea-firs or the ordinary sea-mosses; for these two groups consist of fixed organisms, whereas the graptolites were certainly free-floating creatures, living at large in the open sea. the only hydroid zoophytes or polyzoans which have a similar free mode of existence, have either no skeleton at all, or have hard structures quite unlike the horny sheaths of the graptolites. the second great group of coelenterate animals (_actinozoa_) is represented in the lower silurian rocks by numerous corals. these, for obvious reasons, are much more abundant in regions where the lower silurian series is largely calcareous (as in north america) than in districts like wales, where limestones are very feebly developed. the lower silurian corals, though the first of their class, and presenting certain peculiarities, may be regarded as essentially similar in nature to existing corals. these, as is well known, are the calcareous skeletons of animals--the so-called "coral-zoophytes"--closely allied to the common sea-anemones in structure and habit. a _simple_ coral (fig. ) consists of a calcareous cup embedded in the soft tissues of the flower-like polype, and having at its summit a more or less deep depression (the "calice") in which the digestive organs are contained. the space within the coral is divided into compartments by numerous vertical calcareous plates (the "septa"), which spring from the inside of the wall of the cup, and of which some generally reach the centre. _compound_ corals, again (fig. ), consist of a greater or less number of structures similar in structure to the above, but united together in different ways into a common mass. _simple_ corals, therefore, are the skeletons of _single_ and independent polypes; whilst _compound_ corals are the skeletons of assemblages or colonies of similar polypes, living united with one another another as an organic community. [illustration: fig. .--_zaphrentis stokesi_, a simple "cup-coral," upper silurian, canada. (after billings.)] [illustration: fig. .--upper surface of a mass of _strombodes pentagonus_. upper silurian, canada. (after billings.)] in the general details of their structure, the lower silurian corals do not differ from the ordinary corals of the present day. the latter, however, have the vertical calcareous plates of the coral ("septa") arranged in multiples of six or five; whereas the former have these structures arranged in multiples of four, and often showing a cross-like disposition. for this reason, the common lower silurian corals are separated to form a distinct group under the name of _rugose_ corals or _rugosa_. they are further distinguished by the fact that the cavity of the coral ("visceral chamber") is usually subdivided by more or less numerous horizontal calcareous plates or partitions, which divide the coral into so many tiers or storeys, and which are known as the "tabulæ" (fig. ). [illustration: fig. .--_columnaria alveolata_, a rugose compound coral, with imperfect septa, but having the corallites partitioned off into storeys by "tabulæ." lower silurian, canada. (after billings.)] in addition to the rugose corals, the lower silurian rocks contain a number of curious compound corals, the tubes of which have either no septa at all or merely rudimentary ones, but which have the transverse partitions or "tabulæ" very highly developed. these are known as the _tabulate corals_; and recent researches on some of their existing allies (such as _heliopora_) have shown that they are really allied to the modern sea-pens, organ-pipe corals, and red coral, rather than to the typical stony corals. amongst the characteristic rugose corals of the lower silurian may be mentioned species belonging to the genera _columnaria, favistella, streptelasma_, and _zaphrentis_; whilst amongst the "tabulate" corals, the principal forms belong to the genera _choetetes, halysites_ (the chain-coral), _constellaria_, and _heliolites_. these groups of the corals, however, attain a greater development at a later period, and they will be noticed more particularly hereafter. [illustration: fig. .--group of cystideans. a, _caryocrinus ornatus_,[ ] upper silurian, america; b, _pleurocystites squamosus_, showing two short "arms," lower silurian, canada; c, _pseudocrinus bifasciatus_, upper silurian, england; d, _lepadocrinus gebhartii_, upper silurian, america. (after hall, billings, and salter.)] [footnote : the genus _caryocrinus_ is sometimes regarded as properly belonging to the _crinoids_, but there seem to be good reasons for rather considering it as an abnormal form of _cystidean_.] passing onto higher animals, we find that the class of the _echinodermata_ is represented by examples of the star-fishes (_asteroidea_), the sea-lilies (_crinoidea_), and the peculiar extinct group of the cystideans (_cystoidea_), with one or two of the brittle-stars (_ophiuroidea_)--the sea-urchins (_echinoidea_) being still wanting. the crinoids, though in some places extremely numerous, have not the varied development that they possess in the upper silurian, in connection with which their structure will be more fully spoken of. in the meanwhile, it is sufficient to note that many of the calcareous deposits of the lower silurian are strictly entitled to the name of "crinoidal limestones," being composed in great part of the detached joints, and plates, and broken stems, of these beautiful but fragile organisms (see fig. ). allied to the crinoids are the singular creatures which are known as _cystideans_ (fig. ). these are generally composed of a globular or ovate body (the "calyx"), supported upon a short stalk (the "column"), by which the organism was usually attached to some foreign body. the body was enclosed by closely-fitting calcareous plates, accurately jointed together; and the stem was made up of numerous distinct pieces or joints, flexibly united to each other by membrane. the chief distinction which strikes one in comparing the cystideans with the crinoids is, that the latter are always furnished, as will be subsequently seen, with a beautiful crown of branched and feathery appendages, springing from the summit of the calyx, and which are composed of innumerable calcareous plates or joints, and are known as the "arms." in the cystideans, on the other hand, there are either no "arms" at all, or merely short, unbranched, rudimentary arms. the cystideans are principally, and indeed nearly exclusively, silurian fossils; and though occurring in the upper silurian in no small numbers, they are pre-eminently characteristic of the llandeilo-caradoc period of lower silurian time. they commenced their existence, so far as known, in the upper cambrian; and though examples are not absolutely unknown in later periods, they are pre-eminently characteristic of the earlier portion of the palæozoic epoch. [illustration: fig. .--lower silurian crustaceans. a, _asaphus tyrannus_, upper llandeilo; b. _ogygia buchii_, upper llandeilo; c, _trinucleus concentricus_, caradoc; d, _caryocaris wrightii_, arenig (skiddaw slates); e, _beyrichia complicata_, natural size and enlarged, upper llandeilo and caradoc; f, _primitia strangulata_, caradoc: g. head-shield of _calymene blumenbachii_, var. _brevicapitata_, caradoc; h, head-shield of _triarthrus becki_ (utica slates), united states: i, shield of _leperditia canadensis_, var. _josephiana_, of the natural size, trenton limestone, canada; j, the same, viewed from the front. (after salter, m'coy, rupert jones, and dana.)] the ringed worms (_annelides_) are abundantly represented in the lower silurian, but principally by tracks and burrows similar in essential respects to those which occur so commonly in the cambrian formation, and calling for no special comment. much more important are the _articulate_ animals, represented as heretofore, wholly by the remains of the aquatic group of the _crustaceans_. amongst these are numerous little bivalved forms--such as species of _primitia_ (fig. , f), _beyrichia_ (fig. , e), and _leperditia_ (fig. , i and j). most of these are very small, varying from the size of a pin's head up to that of a hemp seed; but they are sometimes as large as a small bean (fig. , i), and they are commonly found in myriads together in the rock. as before said, they belong to the same great group as the living water-fleas (_ostracoda_). besides these, we find the pod-shaped head-shields of the shrimp-like phyllopods--such as _caryocaris_ (fig. , d) and _ceratiocaris_. more important, however, than any of these are the _trilobites_, which may be considered as attaining their maximum development in the lower silurian. the huge _paradoxides_ of the cambrian have now disappeared, and with them almost all the principal and characteristic "primordial" genera, save _olenus_ and _agnostus_. in their place we have a great number of new forms--some of them, like the great _asaphus tyrannus_ of the upper llandeilo (fig. , a), attaining a length of a foot or more, and thus hardly yielding in the matter of size to their ancient rivals. almost every subdivision of the lower silurian series has its own special and characteristic species of trilobites; and the study of these is therefore of great importance to the geologist. a few widely-dispersed and characteristic species have been here figured (fig. ); and the following may be considered as the principal lower silurian genera--_asaphus, ogygia, cheirurus, ampyx, caiymene, trinucleus, lichas, illoenus, Æglina, harpes, remopleurides, phacops, acidaspis_, and _homalonotus_, a few of them passing upwards under new forms into the upper silurian. coming next to the _mollusca_, we find the group of the sea-mosses and sea-mats (_polyzoa_) represented now by quite a number of forms. amongst these are examples of the true lace-corals (_retepora_ and _fenestella_), with their netted fan-like or funnel-shaped fronds; and along with these are numerous delicate encrusting forms, which grew parasitically attached to shells and corals (_hippothoa, alecto_, &c.); but perhaps the most characteristic forms belong to the genus _ptilodictya_ (figs. and ). in this group the frond is flattened, with thin striated edges, sometimes sword-like or scimitar-shaped, but often more or less branched; and it consists of two layers of cells, separated by a delicate membrane, and opening upon opposite sides. each of these little chambers or "cells" was originally tenanted by a minute animal, and the whole thus constituted a compound organism or colony. [illustration: fig. .--_ptilodictya falciformis_. a, small specimen of the natural size; b, cross-section, showing the shape of the frond; c, portion of the surface, enlarged. trenton limestone and cincinnati group, america. (original.)] [illustration: fig. .--a, _ptilodictya acuta_; b, _ptilodictya schafferi_. a, fragment, of the natural size; b, portion, enlarged to show the cells. cincinnati group of ohio and canada. (original.)] [illustration: fig. .--lower silurian brachiopods. a and a', _orthis biforata_, llandeilo-caradoc, britain and america: b, _orthis flabellulum_, caradoc, britain: c, _orthis subquadrata_, cincinnati group, america; c', interior of the dorsal valve of the same: d, _strophomena deltoidea_, llandeilo-caradoc, britain and america. (after meek, hall, and salter.)] the lamp-shells or _brachiopods_ are so numerous, and present such varied types, both in this and the succeeding period of the upper silurian, that the name of "age of brachiopods" has with justice been applied to the silurian period as a whole. it would be impossible here to enter into details as to the many different forms of brachiopods which present themselves in the lower silurian deposits; but we may select the three genera _orthis, strophomena_, and _leptoena_ for illustration, as being specially characteristic of this period, though not exclusively confined to it. the numerous shells which belong to the extensive and cosmopolitan genus _orthis_ (fig. , a, b, c, and fig. , c and d), are usually more or less transversely-oblong or subquadrate, the two valves (as more or less in all the brachiopods) of unequal sizes, generally more or less convex, and marked with radiating ribs or lines. the valves of the shell are united to one another by teeth and sockets, and there is a straight hinge-line. the beaks are also separated by a distinct space ("hinge-area"), formed in part by each valve, which is perforated by a triangular opening, through which, in the living condition, passed a muscular cord attaching the shell to some foreign object. the genus _strophomena_ (fig. , d, and , a and b) is very like _orthis_ in general character; but the shell is usually much flatter, one or other valve often being concave, the hinge-line is longer, and the aperture for the emission of the stalk of attachment is partially closed by a calcareous plate. in _leptoena_, again (fig. , e), the shell is like _strophomena_ in many respects, but generally comparatively longer, often completely semicircular, and having one valve convex and the other valve concave. amongst other genera of brachiopods which are largely represented in the lower silurian rocks may be mentioned _lingula, crania, discina, trematis, siphonotreta, acrotreta, rhynchonella_, and _athyris_; but none of these can claim the importance to which the three previously-mentioned groups are entitled. [illustration: fig. .--lower silurian brachiopods, a, _strophomena alternata_, cincinnati group, america; b, _strophomena filitexta, trenton and cincinnati groups, america; c, _orthis testudinaria_, caradoc, europe, and america; d, d', _orthis plicateila_, cincinnati group, america; e, e', e'', _leptoena sericea_, llandeilo and caradoc, europe and america. (after meek, hall, and the author.)] the remaining lower silurian groups of _mollusca_ can be but briefly glanced at here. the bivalves (_lamellibranchiata_) find numerous representatives, belonging to such genera as _modiolopsis, ctenodonta, orthonota, paloearca, lyrodesma, ambonychia_, and _cleidophorus_. the univalves (_gasteropoda_) are also very numerous, the two most important genera being _murchisonia_ (fig. ) and _pleurotomaria_. in both these groups the outer lip of the shell is notched; but the shell in the former is elongated and turreted, whilst in the latter it is depressed. the curious oceanic univalves known as the _heteropods_ are also very abundant, the principal forms belonging to _bellerophon_ and _maclurea_. in the former (fig. ) there is a symmetrical convoluted shell, like that of the pearly nautilus in shape, but without any internal partitions, and having the aperture often expanded and notched behind. the species of _maclurea_ (fig. ) are found both in north america and in scotland, and are exclusively confined to the lower silurian period, so far as known. they have the shell coiled into a flat spiral, the mouth being furnished with a very curious, thick, and solid lid or "operculum." the lower silurian _pteropods_, or "winged snails," are numerous, and belong principally to the genera _theca, conularia_, and _tentaculites_, the last-mentioned of these often being extremely abundant in certain strata. [illustration: fig. .--_murchisonia gracilis_, trenton limestone, america. (after billings.)] [illustration: fig. .--different views of _bellerophon argo_, trenton limestone, canada. (after billings.)] [illustration: fig. .--different views of _maclurea crenulata_, quebec group, newfoundland. (after billings.)] [illustration: fig. .--fragment of _orthoceras crebriseptum_, cincinnati group, north america, of the natural size. the lower figure section showing the air-chambers, and the form and position of the siphuncle. (after billings.)] [illustration: fig. .--[ ] restoration of orthoceras, the shell being supposed to be divided vertically, and only its upper part being shown. a, arms; f, muscular tube ("funnel") by which water is expelled from the mantle-chamber; c, air-chambers; s, siphuncle.] [footnote : this illustration is taken from a rough sketch made by the author many years ago, but he is unable to say from what original source it was copied.] lastly, the lower silurian rocks have yielded a vast number of chambered shells, referable to animals which belong to the same great division as the cuttle-fishes (the _cephalopoda_), and of which the pearly nautilus is the only living representative at the present day. in this group of _cephalopods_ the animal possesses a well-developed external shell, which is divided into chambers by shelly partitions ("septa"). the animal lives in the last-formed and largest chamber of the shell, to which it is organically connected by muscular attachments. the head is furnished with long muscular processes or "arms," and can be protruded from the mouth of the shell at will, or again withdrawn within it. we learn, also, from the pearly nautilus, that these animals must have possessed two pairs of breathing organs or "gills;" hence all these forms are grouped together under the name of the "tetrabranchiate" cephalopods (gr. _tetra_, four; _bragchia_, gill). on the other hand, the ordinary cuttle-fishes and calamaries either possess an internal skeleton, or if they have an external shell, it is not chambered; their "arms" are furnished with powerful organs of adhesion in the form of suckers; and they possess only a single pair of gills. for this last reason they are termed the "dibranchiate" cephalopods (gr. _dis_, twice; _bragchia_, gill). no trace of the true cuttle-fishes has yet been found in lower silurian deposits; but the tetrabranchiate group is represented by a great number of forms, sometimes of great size. the principal lower silurian genus is the well-known and widely-distributed _orthoceras_ (fig. ). the shell in this genus agrees with that of the existing _pearly nautilus_, in consisting of numerous chambers separated by shelly partitions (or septa), the latter being perforated by a tube which runs the whole length of the shell after the last chamber, and is known as the "siphuncle" (fig. , s). the last chamber formed is the largest, and in it the animal lives. the chambers behind this are apparently filled with some gas secreted by the animal itself; and these are supposed to act as a kind of float, enabling the creature to move with ease under the weight of its shell. the various air-chambers, though the siphuncle passes through them, have no direct connection with one another; and it is believed that the animal has the power of slightly altering its specific gravity, and thus of rising or sinking in the water by driving additional fluid into the siphuncle or partially emptying it. the _orthoceras_ further agrees with the pearly nautilus in the fact that the partitions or septa separating the different air-chambers are simple and smooth, concave in front and convex behind, and devoid of the elaborate lobation which they exhibit in the ammonites; whilst the siphuncle pierces the septa either in the centre or near it. in the nautilus, however, the shell is coiled into a flat spiral; whereas in _orthoceras_ the shell is a straight, longer or shorter cone, tapering behind, and gradually expanding towards its mouth in front. the chief objections to the belief that the animal of the _orthoceras_ was essentially like that of the pearly nautilus are--the comparatively small size of the body-chamber, the often contracted aperture of the mouth, and the enormous size of some specimens of the shell. thus, some _orthocerata_ have been discovered measuring ten or twelve feet in length, with a diameter of a foot at the larger extremity. these colossal dimensions certainly make it difficult to imagine that the comparatively small body-chamber could have held an animal large enough to move a load so ponderous as its own shell. to some, this difficulty has appeared so great that they prefer to believe that the _orthoceras_ did not live in its shell at all, but that its shell was an internal skeleton similar to what we shall find to exist in many of the true cuttle-fishes. there is something to be said in favour of this view, but it would compel us to believe in the existence in lower silurian times of cuttle-fishes fully equal in size to the giant "kraken" of fable. it need only be added in this connection that the lower silurian rocks have yielded the remains of many other tetrabranchiate cephalopods besides _orthoceras_. some of these belong to _cyrtoceras_, which only differs from _orthoceras_ in the bow-shaped form of the shell; others belong to _phragmoceras_, _lituites_, &c.; and, lastly; we have true _nautili_, with their spiral shells, closely resembling the existing pearly nautilus. whilst all the sub-kingdoms of the invertebrate animals are represented in the lower silurian rocks, no traces of vertebrate animals have ever been discovered in these ancient deposits, unless the so-called "conodonts" found by pander in vast numbers in strata of this age [ ] in russia should prove to be really of this nature. these problematical bodies are of microscopic size, and have the form of minute, conical, tooth-shaped spines, with sharp edges, and hollow at the base. their original discoverer regarded them as the horny teeth of fishes allied to the lampreys; but owen came to the conclusion that they probably belonged to invertebrates. the recent investigation of a vast number of similar but slightly larger bodies, of very various forms, in the carboniferous rocks of ohio, has led professor newberry to the conclusion that these singular fossils really are, as pander thought, the teeth of cyclostomatous fishes. the whole of this difficult question has thus been reopened, and we may yet have to record the first advent of vertebrate animals in the lower silurian. [footnote : according to pander, the "conodonts" are found not only in the lower silurian beds, but also in the "ungulite grit" (upper cambrian), as well as in the devonian and carboniferous deposits of russia. should the conodonts prove to be truly the remains of fishes, we should thus have to transfer the first appearance of vertebrates to, at any rate, as early a period as the upper cambrian.] chapter x. the upper silurian period. having now treated of the lower silurian period at considerable length, it will not be necessary to discuss the succeeding group of the _upper silurian_ in the same detail--the more so, as with a general change of _species_ the upper silurian animals belong for the most part to the same great types as those which distinguish the lower silurian. as compared, also, as regards the total bulk of strata concerned, the thickness of the upper silurian is generally very much below that of the lower silurian, indicating that they represent a proportionately shorter period of time. in considering the general succession of the upper silurian beds, we shall, as before, select wales and america as being two regions where these deposits are typically developed. in wales and its borders the general succession of the upper silurian rocks may be taken to be as follows, in ascending order (fig. ):-- ( ) the base of the upper silurian series is constituted by a series of arenaceous beds, to which the name of "may hill sandstone" was applied by sedgwick. these are succeeded by a series of greenish-grey or pale-grey slates ("tarannon shales"), sometimes of great thickness; and these two groups of beds together form what may be termed the "_may hill group_" (upper llandovery of murchison). though not very extensively developed in britain, this zone is one very well marked by its fossils; and it corresponds with the "clinton group" of north america, in which similar fossils occur. in south wales this group is clearly unconformable to the highest member of the subjacent lower silurian (the llandovery group); and there is reason to believe that a similar, though less conspicuous, physical break occurs very generally between the base of the upper and the summit of the lower silurian. ( ) the _wenlock group_ succeeds the may hill group, and constitutes the middle member of the upper silurian. at its base it may have an irregular limestone ("woolhope limestone"), and its summit may be formed by a similar but thicker calcareous deposit ("wenlock limestone"); but the bulk of the group is made up of the argillaceous and shaly strata known as the "wenlock shale." in north wales the wenlock group is, represented by a great accumulation of flaggy and gritty strata (the "denbighshire flags and grits"), and similar beds (the "coniston flags" and "coniston grits") take the same place in the north of england. ( ) the _ludlow group_ is the highest member of the upper silurian, and consists typically of a lower arenaceous and shaly series (the "lower ludlow rock") a middle calcareous member (the "aymestry limestone"), and an upper shaly and sandy series (the "upper ludlow rock" and "downton sandstone"). at the summit, or close to the summit, of the upper ludlow, is a singular stratum only a few inches thick (varying from an inch to a foot), which contains numerous remains of crustaceans and fishes, and is well known under the name of the "bone-bed." finally, the upper ludlow rock graduates invariably into a series of red sandy deposits, which, when of a flaggy character, are known locally as the "tile-stones." these beds are probably to be regarded as the highest member of the upper silurian; but they are sometimes looked upon as passage-beds into the old red sandstone, or as the base of this formation. it is, in fact, apparently impossible to draw any actual line of demarcation between the upper silurian and the overlying deposits of the devonian or old red sandstone series. both in britain and in america the lower devonian beds repose with perfect conformity upon the highest silurian beds, and the two formations appear to pass into one another by a gradual and imperceptible transition. the upper silurian strata of britain vary from perhaps or feet in thickness up to or , feet. in north america the corresponding series, though also variable, is generally of much smaller thickness, and may be under feet. the general succession of the upper silurian deposits of north america is as follows:-- ( ) _medina sandstone_.--this constitutes the base of the upper silurian, and consists of sandy strata, singularly devoid of life, and passing below in some localities into a conglomerate ("oneida conglomerate"), which is stated to contain pebbles derived from the older beds, and which would thus indicate an unconformity between the upper and lower silurian. ( ) _clinton group_.--above the medina sandstone are beds of sandstone and shale, sometimes with calcareous bands, which constitute what is known as the "clinton group." the medina and clinton groups are undoubtedly the equivalent of the "may hill group" of britain, as shown by the identity of their fossils. [illustration: fig. . generalized section of the upper silurian strata of wales and shropshire.] ( ) _niagara group_.--this group consists typically of a series of argillaceous beds ("niagara shale") capped by limestones ("niagara limestone"); and the name of the group is derived from the fact that it is over limestones of this age that the niagara river is precipitated to form the great falls. in places the niagara group is wholly calcareous, and it is continued upwards into a series of marls and sandstones, with beds of salt and masses of gypsum (the "salina group"), or into a series of magnesian limestones ("guelph limestones"). the niagara group, as a whole, corresponds unequivocally with the wenlock group of britain. ( ) _lower helderberg group_.--the upper silurian period in north america was terminated by the deposition of a series of calcareous beds, which derive the name of "lower helderberg" from the helderberg mountains, south of albany, and which are divided into several zones, capable of recognition by their fossils, and known by local names (tentaculite limestone, water-lime, lower pentamerus limestone, delthyris shaly limestone, and upper pentamerus limestone). as a whole, this series may be regarded as the equivalent of the ludlow group of britain, though it is difficult to establish any precise parallelism. the summit of the lower heiderberg group is constituted by a coarse-grained sandstone (the "oriskany sandstone"), replete with organic remains, which have to a large extent a silurian _facies_. opinions differ as to whether this sandstone is to be regarded as the highest bed of the upper silurian or the base of the devonian. we thus see that in america, as in britain, no other line than an artificial one can be drawn between the upper silurian and the overlying devonian. as regards the _life_ of the upper silurian period, we have, as before, a number of so-called "fucoids," the true vegetable nature of which is in many instances beyond doubt. in addition to these, however, we meet for the first time, in deposits of this age, with the remains of genuine land-plants, though our knowledge of these is still too scanty to enable us to construct any detailed picture of the terrestrial vegetation of the period. some of these remains indicate the existence of the remarkable genus _lepidodendron_--a genus which played a part of great importance in the forests of the devonian and carboniferous periods, and which may be regarded as a gigantic and extinct type of the club-mosses (_lycopodiaceoe_). near the summit of the ludlow formation in britain there have also been found beds charged with numerous small globular bodies, which dr hooker has shown to be the seed-vessels or "sporangia" of club-mosses. principal dawson further states that he has seen in the same formation fragments of wood with the structure of the singular devonian conifer known as _prototaxites_. lastly, the same distinguished observer has described from the upper silurian of north america the remains of the singular land-plants belonging to the genus _psilophyton_, which will be referred to at greater length hereafter. the marine life of the upper silurian is in the main constituted by types of animals similar to those characterising the lower silurian, though for the most part belonging to different species. the _protozoans_ are represented principally by _stromatopora_ and _ischadites_, along with a number of undoubted sponges (such as _amphispongia, astroeospongia, astylospongia_, and _paloeomanon_). amongst the _coelenterates_, we find the old group of _graptolites_ now verging on extinction. individuals still remain numerous, but the variety of generic and specific types has now become greatly reduced. all the branching and complex forms of the arenig, the twin-graptolites and _dicranograpti_ of the llandeilo, and the double-celled _diplograpti_ and _climacograpti_ of the bala group, have now disappeared. in their place we have the singular _retiolites_, with its curiously-reticulated skeleton; and several species of the single-celled genus _monograptus_, of which a characteristic species (_m. priodon_) is here figured. if we remove from this group the plant-like _dictyonemoe_, which are still present, and which survive into the devonian, no known species of _graptolite_ has hitherto been detected in strata higher in geological position than the ludlow. this, therefore, presents us with the first instance we have as yet met with of the total disappearance and extinction of a great and important series of organic forms. [illustration: fig. .--a, _monograptus priodon_, slightly enlarged. b, fragment of the same viewed from behind. c, fragment of the same viewed in front, showing the mouths of the cellules. d, cross-section of the same. from the wenlock group (coniston flags of the north of england). (original.)] the _corals_ are very numerously represented in the upper silurian rocks some of the limestones (such as the wenlock limestone) being often largely composed of the skeletons of these animals. almost all the known forms of this period belong to the two great divisions of the rugose and tabulate corals, the former being represented by species of _zaphrentis, omphyma, cystiphyllum, strombodes, acervularia, cyathophyllum_, &c.; whilst the latter belong principally to the genera _favosites, choetetes, halysites, syringopora, heliolites_, and _plasmopora_. amongst the _rugosa_, the first appearance of the great and important genus _cyathophyllum_, so characteristic of the palæozoic period, is to be noted; and amongst the _tabulata_ we have similarly the first appearance, in force at any rate, of the widely-spread genus _favosites_--the "honeycomb-corals." the "chain-corals" (_halysites_), figured below (fig. ), are also very common examples of the tabulate corals during this period, though they occur likewise in the lower silurian. [illustration: fig. .--a, _halysites catenularia_, small variety, of the natural size; b, fragment of a large variety of the same, of the natural size; c, fragment of limestone with the tubes of _halysites agglomerata_, of the natural size; d, vertical section of two tubes of the same, showing the tabulæ, enlarged. niagara limestone (wenlock), canada. (original.)] [illustration: fig. .--upper silurian star-fishes. , _palasterina primoeva_, lower ludlow; , _paloeaster ruthveni_, lower ludlow; , _paloeocoma colvini_, lower ludlow. (after salter.)] [illustration: fig. .--a, _protaster sedgwickii_, showing the disc and bases of the arms; b, portion of an arm, greatly enlarged. lower ludlow. (after salter.)] amongst the _echinodermata_, all those orders which have hard parts capable of ready preservation are more or less largely represented. we have no trace of the holothurians or sea-cucumbers; but this is not surprising, as the record of the past is throughout almost silent as to the former existence of these soft-bodied creatures, the scattered plates and spicules in their skin offering a very uncertain chance of preservation in the fossil condition. the sea-urchins (_echinoids_) are said to be represented by examples of the old genus _paloechinus_. the star-fishes (_asteroids_) and the brittle-stars (_ophiuroids_) are, comparatively speaking, largely represented; the former by species of _palasterina_ (fig. ), _paloeaster_ (fig. ), _paloeocoma_ (fig. ), _petraster, glyptaster_, and _lepidaster_--and the latter by species of _protaster_ (fig. ), _paloeodiscus, acroura_, and _eucladia_. the singular _cystideans_, or "globe crinoids," with their globular or ovate, tesselated bodies (fig. , a, c, d,), are also not uncommon in the upper silurian; and if they do not become finally extinct here, they certainly survive the close of this period by but a very brief time. by far the most important, however, of the upper silurian echinodenns, are the sea-lilies or _crinoids_. the limestones of this period are often largely composed of the fragmentary columns and detached plates of these creatures, and some of them (such as the wenlock limestone of dudley) have yielded perhaps the most exquisitely-preserved examples of this group with which we are as yet acquainted. however varied in their forms, these beautiful organisms consist of a globular, ovate, or pear-shaped body (the "calyx"), supported upon a longer or shorter jointed stem (or "column"). the body is covered externally with an armour of closely-fitting calcareous plates (fig. ), and its upper surface is protected by similar but smaller plates more loosely connected by a leathery integument. from the upper surface of the body, round its margin, springs a series of longer or shorter flexible processes, composed of innumerable calcareous joints or pieces, movably united with one another. the arms are typically five in number; but they generally subdivide at least once, sometimes twice, and they are furnished with similar but more slender lateral branches or "pinnules," thus giving rise to a crown of delicate feathery plumes. the "column" is the stem by which the animal is attached permanently to the bottom of the sea; and it is composed of numerous separate plates, so jointed together that whilst the amount of movement between any two pieces must be very limited, the entire column acquires more or less flexibility, allowing the organism as a whole to wave backwards and forwards on its stalk. into the exquisite _minutioe_ of structure by which the innumerable parts entering into the composition of a single crinoid are adapted for their proper purposes in the economy of the animal, it is impossible to enter here. no period, as before said, has yielded examples of greater beauty than the upper silurian, the principal genera represented being _cyathocrinus, platycrinus, marsupiocrinus, taxocrinus, eucalyptocrinus, ichthyocrinus, mariacrinus, periechocrinus, glyptocrinus, crotalocrinus_, and _edriocrinus_. [illustration: fig .--upper silurian crinoids. a, calyx and arms of _eucalyptocrinus polydactylus_, wenlock limestone; b, _ichthyocrinus loevis_, niagara limestone, america; c, _taxocrinus tuberculatus_, wenlock limestone. (after m'coy and hall.)] [illustration: fig. .--_planolites vulgaris_, the filled-up burrows of a marine worm. upper silurian (clinton group), canada. (original.)] the tracks and burrows of _annelides_ are as abundant in the upper silurian strata as in older deposits, and have just as commonly been regarded as plants. the most abundant forms are the cylindrical, twisted bodies (planolites), which are so frequently found on the surfaces of sandy beds, and which have been described as the stems of sea-weeds. these fossils (fig. ), however, can be nothing more, in most cases, than the filled-up burrows of marine worms resembling the living lob-worms. there are also various remains which belong to the group of the tube-inhabiting annelides (_tubicola_). of this nature are the tubes of _serpulites_ and _cornultites_, and the little spiral discs of _spirorbis lewisii_. [illustration: fig. .--upper silurian trilobites. a, _cheirurus bimucronatus_, wenlock and caradoc; b, _phacops longicaudatus_, wenlock, britain, and america; c, _phacops downingioe_, wenlock and ludlow; d, _harpes ungula_, upper silurian, bohemia. (after salter and barrande.)] amongst the _articulates_, we still meet only with the remains of _crustaceans_. besides the little bivalved _ostracoda_--which here are occasionally found of the size of beans--and various _phyllopods_ of different kinds, we have an abundance of _trilobites_. these last-mentioned ancient types, however, are now beginning to show signs of decadence; and though still individually numerous, there is a great diminution in the number of generic types. many of the old genera, which flourished so abundantly in lower silurian seas, have now died out; and the group is represented chiefly by species of _cheirurus, encrinurus, harpes, proetus, lichas, acidaspis, illoenus, calymene, homalonotus_, and _phacops_--the last of these, one of the highest and most beautiful of the groups of trilobites, attaining here its maximum of development. in the annexed illustration (fig. ) some of the characteristic upper silurian trilobites are represented--all, however, belonging to genera which have their commencement in the lower silurian period. in addition to the above, the ludlow rocks of britain and the lower helderberg beds of north america have yielded the remains of certain singular crustaceans belonging to the extinct order of the _eurypterida_. some of these wonderful forms are not remarkable for their size; but others, such as _pterygotus anglicus_ (fig. ), attain a length of six feet or more, and may fairly be considered as the giants of their class. the eurypterids are most nearly allied to the existing king-crabs (_limuli_), and have the anterior end of the body covered with a great head-shield, carrying two pairs of eyes, the one simple and the other compound. the feelers are converted into pincers, whilst the last pair of limbs have their bases covered with spiny teeth so as to act as jaws, and are flattened and widened out towards their extremities so as to officiate as swimming-paddles. the hinder extremity of the body is composed of thirteen rings, which have no legs attached to them; and the last segment of the tail is either a flattened plate or a narrow, sword-shaped spine. fragments of the skeleton are easily recognised by the peculiar scale-like markings with which the surface is adorned, and which look not at all unlike the scales of a fish. the most famous locality for these great crustaceans is lesmahagow, in lanarkshire, where many different species have been found. the true king-crabs (_limuli_) of existing seas also appear to have been represented by at least one form (_neolimulus_) in the upper silurian. [illustration: fig. .--_pterygotus anglicus_, viewed from the under side, reduced in size, and restored. c c, the feelers (antennæ), terminating in nipping-claws; o o, eyes; m m, three pairs of jointed limbs, with pointed extremities; n n, swimming-paddles, the bases of which are spiny and act as jaws. upper silurian, lanarkshire. (after henry woodward.)] coming to the _mollusca_, we note the occurrence of the same great groups as in the lower silurian. amongst the sea-mosses (_polyzoa_), we have the ancient lace-corals (_fenestella_ and _retepora_), with the nearly-allied _glauconome_, and species of _ptilodictya_ (fig. ); whilst many forms often referred here may probably have to be transferred to the corals, just as some so-called corals will ultimately be removed to the present group. [illustration: fig. .--upper silurian polyzoa. , fan-shaped frond of _rhinopora verrucosa_; a, portion of the surface of the same, enlarged; and a, _phoenopora ensiformis_, of the natural size and enlarged; and a, _helopora fragilis_, of the natural size and enlarged; and a, _ptilodictya raripora_, of the natural size and enlarged. the specimens are all from the clinton formation (may hill group) of canada. (original.)] [illustration: fig. .--_spirifera hysterica_. the right-hand figure shows the interior of the dorsal valve with the calcareous spires for the support of the arms.] [illustration: fig. .--upper silurian brachiopods. a a', _leptocoelia plano-convexa_, clinton group, america; b b', _rhynchonella neglecta_, clinton group, america; c, _rhynchonella cuneata_, niagara group, america, and wenlock group, britain; d d', _orthis elelgantula_, llandeilo to ludlow, america and europe; e e', _atrypa hemispherica_, clinton group, america, and llandovery and may hill groups, britain; f f', _atrypa congesta_, clinton group, america; g g', _orthis davidsoni_, clinton group, america. (after hall, billings, and the author.)] the brachiopods continued to flourish during the upper silurian period in immense numbers and under a greatly increased variety of forms. the three prominent lower silurian genera _orthis, strophomena_, and _leptoena_ are still well represented, though they have lost their former preeminence. amongst the numerous types which have now come upon the scene for the first time, or which have now a special development, are _spirifera_ and _pentamerus_. in the first of these (fig. . b, c), one of the valves of the shell (the dorsal) is furnished in its interior with a pair of great calcareous spires, which served for the support of the long and fringed fleshy processes or "arms" which were attached to the sides of the mouth.[ ] in the genus _pentamerus_ (fig. ) the shell is curiously subdivided in its interior by calcareous plates. the _pentameri_ commenced their existence at the very close of the lower silurian (llandovery), and survived to the close of the upper silurian; but they are specially characteristic of the may hill and wenlock groups, both in britain and in other regions. one species, _pentamerus galeatus_, is common to sweden, britain, and america. amongst the remaining upper silurian brachiopods are the extraordinary _trimerellids_; the old and at the same time modern _linguloe, discinoe_, and _cranioe_; together with many species of _atrypa_ (fig. , e), _leptocoelia_ (fig. , a), _rhynchonella_ (fig. , b, c), _meristella_ (fig. , a, e, f), _athyris, retzia, chonetes_, &c. [footnote : in all the lamp-shells the mouth is provided with two long fleshy organs, which carry delicate filaments on their sides, and which are usually coiled into a spiral. these organs are known as the "arms," and it is from their presence that the name of "_brachiopoda_" is derived (gr. _brachion_, arm; _podes_, feet). in some cases the arms are merely coiled away within the shell, without any support; but in other cases they are carried upon a more or less elaborate shelly loop, often spoken of as the "carriage-spring apparatus." in the _spirifers_, and in other ancient genera, this apparatus is coiled up into a complicated spiral (fig. ). it is these "arms," with or without the supporting loops or spires, which serve as one of the special characters distinguishing the _brachiopods_ from the true bivalves (_lamellibranchiata_).] [illustration: fig. .-a a', meristella intermedia_, niagara group, america; b, _spirifera niagarensis_, niagara group, america; c c', _spirifera crispa_, may hill to ludlow, britain, and niagara group, america; d, _strophomena (streptorhynchus) subplana_, niagara group, america; e, _meristella naviformis_, niagara group, america; f, _meristella cylindrica_, niagara group, america. (after hall, billings, and the author.)] [illustration: fig. .--_pentamerus knightii_. wenlock and ludlow. the right-hand figure shows the internal partitions of the shell.] [illustration: fig. .--upper silurian bivalves. a, _cardiola interrupta_, wenlock and ludlow; b, _pterinea subfalcata_, wenlock; c, _cardiola fibrosa_, ludlow. (after salter and m'coy.)] [illustration: fig. .--upper silurian gasteropods. a, _platyceras ventricosum_, lower helderberg, america; b, _euomphalus discors_, wenlock, britain; c, _holopella obsoleta_ ludlow, britain; d, _platyschisma helicites_, upper ludlow, britain; e, _holopella gracilior_, wenlock, britain; f, _platyceras multisinuatum_, lower helderberg, america; g, _holopea subconica_, lower helderberg, america; h, h', _platyostoma niagarense_, niagara group, america. (after hall, m'coy, and salter.)] [illustration: fig .--_tentaculites ornatus_. upper silurian of europe and north america.] the higher groups of the _mollusca_ are also largely represented in the upper silurian. apart from some singular types, such as the huge and thick-shelled _megalomi_ of the american wenlock formation, the bivalves (_lamellibranchiata_) present little of special interest; for though sufficiently numerous, they are rarely well preserved, and their true affinities are often uncertain. amongst the most characteristic genera of this period may be mentioned _cardiola_ (fig. , a and c) and _pterinea_ (fig. , b), though the latter survives to a much later date. the univalves (_gasteropoda_) are very numerous, and a few characteristic forms are here figured (fig. ). of these, no genus is perhaps more characteristic than _euomphalus_ (fig. , b), with its flat discoidal shell, coiled up into an oblique spiral, and deeply hollowed out on one side; but examples of this group are both of older and of more modern date. another very extensive genus, especially in america, is platyceras (fig. , a and f), with its thin fragile shell--often hardly coiled up at all--its minute spire, and its widely-expanded, often sinuated mouth. the british _acroculioe_ should probably be placed here, and the group has with reason been regarded as allied to the violet-snails (_ianthina_) of the open atlantic. the species of _platyostoma_ (fig. , h) also belong to the same family; and the entire group is continued throughout the devonian into the carboniferous. amongst other well-known upper silurian gasteropods are species of the genera _holopea_ (fig. , g), _holopella_ (fig. . e), _platyschisma_ (fig. , d), _cyclonema, pleurotomaria, murchisonia, trochonema_, &c. the oceanic univalves (_heteropods_) are represented mainly by species of _bellerophon_; and the winged snails, or _pteropods_, can still boast of the gigantic _thecoe_ and _conularioe_, which characterise yet older deposits. the commonest genus of _pteropoda_, however, is _tentaculites_ (fig. ), which clearly belongs here, though it has commonly been regarded as the tube of an annelide. the shell in this group is a conical tube, usually adorned with prominent transverse rings, and often with finer transverse or longitudinal striæ as well; and many beds of the upper silurian exhibit myriads of such tubes scattered promiscuously over their surfaces. the last and highest group of the _mollusca_--that of the _cephalopoda_--is still represented only by _tetrabranchiate_ forms; but the abundance and variety of these is almost beyond belief. many hundreds of different species are known, chiefly belonging to the straight _orthoceratites_, but the slightly-curved _cyrtoceras_ is only little less common. there are also numerous forms of the genera _phragmoceras, ascoceras, gyroteras, lituites_, and _nautilus_. here, also, are the first-known species of the genus _goniatites_--a group which attains considerable importance in later deposits, and which is to be regarded as the precursor of the _ammonites_ of the secondary period. [illustration: fig. .--head-shield of _pteraspis banksii_, ludlow rocks. (after murchison.)] [illustration: fig. .--a, spine of _onchus tenuistriatus_; b, shagreen-scales of _thelodus_. both from the "bone-bed" of the upper ludlow rocks. (after murchison.)] finally, we find ourselves for the first time called upon to consider the remains of undoubted vertebrate animals, in the form of _fishes_. the oldest of these remains, so far as yet known, are found in the lower ludlow rocks, and they consist of the bony head-shields or bucklers of certain singular armoured fishes belonging to the group of the _ganoids_, represented at the present day by the sturgeons, the gar-pikes of north america, and a few other less familiar forms. the principal upper silurian genus of these is _pteraspis_, and the annexed illustration (fig. ) will give some idea of the extraordinary form of the shield covering the head in these ancient fishes. the remarkable stratum near the top of the ludlow formation known as the "bone-bed" has also yielded the remains of shark-like fishes. some of these, for which the name of _onchus_ has been proposed, are in the form of compressed, slightly-curved spines (fig. , a), which would appear to be of the nature of the strong defensive spines implanted in front of certain of the fins in many living fishes. besides these, have been found fragments of prickly skin or shagreen (_sphagodus_), along with minute cushion-shaped bodies (_thelodus_, fig. , b), which are doubtless the bony scales of some fish resembling the modern dog-fishes. as the above mentioned remains belong to two distinct, and at the same time highly-organised, groups of the fishes, it is hardly likely that we are really presented here with the first examples of this great class. on the contrary, whether the so-called "conodonts" should prove to be the teeth of fishes or not, we are justified in expecting that unequivocal remains of this group of animals will still be found in the lower silurian. it is interesting, also, to note that the first appearance of fishes--the lowest class of vertebrate animals--so far as known to us at present, does not take place until after all the great sub-kingdoms of invertebrates have been long in existence; and there is no reason for thinking that future discoveries will materially affect the _relative_ order of succession thus indicated. literature. from the vast and daily-increasing mass of silurian literature, it is impossible to do more than select a small number of works which have a classical and historical interest to the english-speaking geologist, or which embody researches on special groups of silurian animals--anything like an enumeration of all the works and papers on this subject being wholly out of the question. apart, therefore, from numerous and in many cases extremely important memoirs, by various well-known observers, both at home and abroad, the following are some of the more weighty works to which the student may refer in investigating the physical characters and succession of the silurian strata and their fossil contents:-- ( ) 'siluria.' sir roderick murchison. ( ) 'geology of russia in europe.' murchison (with m. de verneuil and count von keyserling). ( ) 'bassin silurien de bohême centrale.' barrande. ( ) 'introduction to the catalogue of british palæozoic fossils in the woodwardian museum of cambridge.' sedgwick. ( ) 'die urwelt russlands.' eichwald. ( ) 'report on the geology of londonderry, tyrone,' &c. portlock. ( ) "geology of north wales"--'mem. geol. survey of great britain,' vol. iii. ramsay. ( ) 'geology of canada,' . sir w. e. logan; and the 'reports of progress of the geological survey' since . ( ) 'memoirs of the geological survey of great britain,' ( ) 'reports of the geological surveys of the states of new york, illinois, ohio, iowa, michigan, vermont, wisconsin, minnesota,' &c. by emmons, hall, worthen, meek, newberry, orton, winchell, dale owen, &c. ( ) 'thesaurus siluricus.' bigsby. ( ) 'british palæozoic fossils.' m'coy. ( ) 'synopsis of the silurian fossils of ireland,' m'coy. ( ) "appendix to the geology of north wales"--'mem. geol. survey,' vol. iii. salter. ( ) 'catalogue of the cambrian and silurian fossils in the woodwardian museum of cambridge.' salter. ( ) 'characteristic british fossils.' baily. ( ) 'catalogue of british fossils.' morris. ( ) 'palæozoic fossils of canada.' billings. ( ) 'decades of the geological survey of canada.' billings, salter, rupert jones. ( ) 'decades of the geological survey of great britain.' salter, edward, forbes. ( ) 'palæontology of new york,' vols. i.-iii. hall. ( ) 'palæontology of illinois.' meek and worthen. ( ) 'palæontology of ohio.' meek, hall, whitfield, nicholson. ( ) 'silurian fauna of west tennessee' (silurische fauna des westlichen tennessee). ferdinand roemer. ( ) 'reports on the state cabinet of new york.' hall. ( ) 'lethæa geognostica.' bronn. ( ) 'index palæontologicus.' bronn. ( ) 'lethæa rossica.' eichwald. ( ) 'lethæa suecica.' hisinger. ( ) 'palæontologica suecica.' angelin. ( ) 'petrefacta germaniæ.' goldfuss. ( ) 'versteinerungen der grauwacken-formation in sachsen.' geinitz. ( ) 'organisation of trilobites' (ray society). burmeister. ( ) 'monograph of the british trilobites' (palæontographical society). salter. ( ) 'monograph of the british merostomata' (palæontographical society). henry woodward. ( ) 'monograph of british brachiopoda' (palæontographical society). thomas davidson. ( ) 'graptolites of the quebec group.' james hall. ( ) 'monograph of the british graptolitidæ.' nicholson. ( ) 'monographs on the trilobites. pteropods, cephalopods, graptolites,' &c. extracted from the 'système silurien du centre de la bohême.' barrande. ( ) 'polypiers fossiles des terrains paleozoiques,' and 'monograph of the british corals' (palæontographical society). milne edwards and jules haime. chapter xi. the devonian and old red sandstone period. between the summit of the ludlow formation and the strata which are universally admitted to belong to the carboniferous series is a great system of deposits, to which the name of "old red sandstone" was originally applied, to distinguish them from certain arenaceous strata which lie above the coal ("new red sandstone"). the old red sandstone, properly so called, was originally described and investigated as occurring in scotland and in south wales and its borders; and similar strata occur in the south of ireland. subsequently it was discovered that sediments of a different mineral nature, and containing different organic remains, intervened between the silurian and the carboniferous rocks on the continent of europe, and strata with similar palæontological characters to these were found occupying a considerable area in devonshire. the name of "devonian" was applied to these deposits; and this title, by common usage, has come to be regarded as synonymous with the name of "old red sandstone." lastly, a magnificent series of deposits, containing marine fossils, and undoubtedly equivalent to the true "devonian" of devonshire, rhenish prussia, belgium, and france, is found to intervene in north america between the summit of the silurian and the base of the carboniferous rocks. much difficulty has been felt in correlating the true "devonian rocks" with the typical "old red sandstone"--this difficulty arising from the fact that though both formations are fossiliferous, the peculiar fossils of each have only been rarely and partially found associated together. the characteristic crustaceans and many of the characteristic fishes of the old red are wanting in the devonian; whilst the corals and marine shells of the latter do not occur in the former. it is impossible here to enter into any discussion as to the merits of the controversy to which this difficulty has given origin. no one, however, can doubt the importance and reality of the devonian series as an independent system of rocks to be intercalated in point of time between the silurian and the carboniferous. the want of agreement, both lithologically and palæontologically, between the devonian and the old red, can be explained by supposing that these two formations, though wholly or in great part _contemporaneous_, and therefore strict equivalents, represent deposits in two different geographical areas, laid down under different conditions. on this view, the typical devonian rocks of europe, britain, and north america are the deep-sea deposits of the devonian period, or, at any rate, are genuine marine sediments formed far from land. on the other hand, the "old red sandstone" of britain and the corresponding "gaspé group" of eastern canada represent the shallow-water shore-deposits of the same period. in fact, the former of these last-mentioned deposits contains no fossils which can be asserted positively to be _marine_ (unless the eurypterids be considered so); and it is even conceivable that it represents the sediments of an inland sea. accepting this explanation in the meanwhile, we may very briefly consider the general succession of the deposits of this period in scotland, in devonshire, and in north america. in scotland the "old red" forms a great series of arenaceous and conglomeratic strata, attaining a thickness of many thousands of feet, and divisible into three groups. of these, the _lower old red sandstone_ reposes with perfect conformity upon the highest beds of the upper silurian, the two formations being almost inseparably united by an intermediate series of "passage-beds." in mineral nature this group consists principally of massive conglomerates, sandstones, shales, and concretionary limestones; and its fossils consist chiefly of large crustaceans belonging to the family of the _eurypterids_, fishes, and plants. the _middle old red sandstone_ consists of flagstones, bituminous shales, and conglomerates, sometimes with irregular calcareous bands; and its fossils are principally fishes and plants. it may be wholly wanting, when the _upper old red_ seems to repose unconformably upon the lower division of the series. the _upper old red sandstone_ consists of conglomerates and grits, along with a great series of red and yellow sandstones--the fossils, as before, being fishes and remains of plants. the upper old red graduates upwards conformably into the carboniferous series. the devonian rocks of devonshire are likewise divisible into a lower, middle, and upper division. the _lower devonian_ or _lynton group_ consists of red and purple sandstones, with marine fossils, corresponding to the "spirifer sandstein" of germany, and to the arenaceous deposits (schoharie and cauda-galli grits) at the base of the american devonian. the _middle devonian_ or _ilfracombe group_ consists of sandstones and flags, with calcareous slates and crystalline limestones, containing many corals. it corresponds with the great "eifel limestone" of the continent, and, in a general way, with the corniferous limestone and hamilton group of north america. the _upper devonian_ or _pilton group_, lastly, consists of sandstones and calcareous shales which correspond with the "clymenia limestone" and "cypridina shales" of the continent, and with the chemung and portage groups of north america. it seems quite possible, also, that the so-called "carboniferous slates" of ireland correspond with this group, and that the former would be more properly regarded as forming the summit of the devonian than the base of the carboniferous. in no country in the world, probably, is there a finer or more complete exposition of the strata intervening between the silurian and carboniferous deposits than in the united states. the following are the main subdivisions of the devonian rocks in the state of new york, where the series may be regarded as being typically developed (fig. ):-- ( ) _cauda-galli grit_ and _schoharie grit_.--considering the "oriskany sandstone" as the summit of the upper silurian, the base of the devonian is constituted by the arenaceous deposits known by the above names, which rest quite conformably upon the silurian, and which represent the lower devonian of devonshire. the _cauda-galli grit_ is so called from the abundance of a peculiar spiral fossil (_spirophyton cauda-galli_), which is of common occurrence in the carboniferous rocks of britain, and is supposed to be the remains of a sea-weed. ( ) the _corniferous_ or _upper helderberg limestone_.--a series of limestones usually charged with considerable quantities of siliceous matter in the shape of hornstone or chert (lat. _cornu_, horn). the thickness of this group rarely exceeds feet; but it is replete with fossils, more especially with the remains of corals. the corniferous limestone is the equivalent of the coral-bearing limestones of the middle devonian of devonshire and the great "eifel limestone" of germany. ( ) the _hamilton group_--consisting of shales at the base ("marcellus shales"); flags, shales, and impure limestones ("hamilton beds") in the middle; and again a series of shales ("genesee slates") at the top. the thickness of this group varies from to feet, and it is richly charged with marine fossils. ( ) the _portage group_.--a great series of shales, flags, and shaly sandstones, with few fossils. ( ) the _chemung group_.--another great series of sandstones and shales, but with many fossils. the portage and chemung groups may be regarded as corresponding with the upper devonian of devonshire. the chemung beds are succeeded by a great series of red sandstones and shales--the "catskill group"--which pass conformably upwards into the carboniferous, and which may perhaps be regarded as the equivalent of the great sandstones of the upper old red in scotland. throughout the entire series of devonian deposits in north america no unconformability or physical break of any kind has hitherto been detected; nor is there any marked interruption to the current of life, though each subdivision of the series has its own fossils. no completely natural line can thus be indicated, dividing the devonian in this region from the silurian on the one hand, and the carboniferous on the other hand. at the same time, there is the most ample evidence, both stratigraphical and palæontological, as to the complete independence of the american devonian series as a distinct life-system between the older silurian and the later carboniferous. the subjoined section (fig. ) shows diagrammatically the general succession of the devonian rocks of north america. [illustration: fig. . generalized section of the devonian rocks of north america.] [illustration: fig. .--restoration of _psilophyton princeps_. devonian, canada. (after dawson.)] as regards the _life_ of the devonian period, we are now acquainted with a large and abundant terrestrial _flora_--this being the first time that we have met with a land vegetation capable of reconstruction in any fulness. by the researches of goeppert, unger, dawson, carruthers, and other botanists, a knowledge has been acquired of a large number of devonian plants, only a few of which can be noticed here. as might have been anticipated, the greater number of the vegetable remains of this period have been obtained from such shallow-water deposits as the old red sandstone proper and the gaspè series of north america, and few traces of plant-life occur in the strictly marine sediments. apart from numerous remains, mostly of a problematical nature, referred to the comprehensive group of the sea-weeds, a large number of ferns have now been recognised, some being, of the ordinary plant-like type (_pecopteris, neuropteris, alethopteris, sphenopteris_, &c.), whilst others belong to the gigantic group of the "tree-ferns" (_psaronius, caulopteris_, &c.) besides these there is an abundant development of the singular extinct types of the _lepidodendroids_, the _sigillarioids_, and the _calamites_, all of which attained their maximum in the carboniferous. of these, the _lepidodendra_ may be regarded as gigantic, tree-like club-mosses (_lycopodiaceoe_); the _calamites_ are equally gigantic horse-tails (_equisetaceoe_); and the _sigillarioids_, equally huge in size, in some respects hold a position intermediate between the club-mosses and the pines (conifers). the devonian rocks have also yielded traces of many other plants (such as _annularia, asterophyllites, cardiocarpon_, &c.), which acquire a greater pre-dominance in the carboniferous period, and which will be spoken of in discussing the structure of the plants of the coal-measures. upon the whole, the one plant which may be considered as specially characteristic of the devonian (though not confined to this series) is the _psilophyton_ (fig. ) of dr dawson. these singular plants have slender branching stems, with sparse needle-shaped leaves, the young stems being at first coiled up, crosier-fashion, like the young fronds of ferns, whilst the old branches carry numerous spore-cases. the stems and branches seem to have attained a height of two or three feet; and they sprang from prostrate "root-stocks" or creeping stems. upon the whole, principal dawson is disposed to regard _psilophyton_ as a "generalised type" of plants intermediate between the ferns and the club-mosses. lastly, the devonian deposits have yielded the remains of the first actual _trees_ with which we are as yet acquainted. about the nature of some of these (_ormoxylon_ and _dadoxylon_) no doubt can be entertained, since their trunks not only show the concentric rings of growth characteristic of exogenous trees in general, but their woody tissue exhibits under the microscope the "discs" which are characteristic of the wood of the pines and firs (see fig. ). the singular genus _prototaxites_, however, which occurs in an older portion of the devonian series than the above, is not in an absolutely unchallenged position. by principal dawson it is regarded as the trunk of an ancient _conifer_--the most ancient known; but mr carruthers regards it as more probably the stem of a gigantic sea-weed. the trunks of _prototaxites_ (fig. , a) vary from one to three feet in diameter, and exhibit concentric rings of growth; but its woody fibres have not hitherto been clearly demonstrated to possess discs. before leaving the devonian vegetation, it may be mentioned that the hornstone or chert so abundant in the corniferous limestone of north america has been shown to contain the remains of various microscopic plants (_diatoms_ and _desmids_). we find also in the same siliceous material the singular spherical bodies, with radiating spines, which occur so abundantly in the chalk flints, and which are termed _xanthidia_. these may be regarded as probably the spore-cases of the minute plants known as _desmidioe_. [illustration: fig. .--a, trunk of _prototaxites logani_, eighteen inches in diameter, as seen in the cliff near l'anse brehaut, gaspé; b, two wood-cells showing spiral fibres and obscure pores, highly magnified. lower devonian, canada. (after dawson)] the devonian _protozoans_ have still to be fully investigated. true sponges (such as _astrtoeospongia, sphoerospongia_, &c.) are not unknown; but by far the commonest representatives of this sub-kingdom in the devonian strata are _stromatopora_ and its allies. these singular organisms (fig. ) are not only very abundant in some of the devonian limestones--both in the old world and the new--but they often attain very large dimensions. however much they may differ in minor details, the general structure of these bodies is that of numerous, concentrically-arranged, thin, calcareous laminæ, separated by narrow interspaces, which in turn are crossed by numerous delicate vertical pillars, giving the whole mass a cellular structure, and dividing it into innumerable minute quadrangular compartments. many of the devonian _stromatoporoe_ also exhibit on their surface the rounded openings of canals, which can hardly have served any other purpose than that of permitting the sea-water to gain ready access to every part of the organism. [illustration: fig. .--a, part of the under surface of _stromatopora tuberculata_, showing the wrinkled basement membrane and the openings of water-canals, of the natural size; b, portion of the upper surface of the same, enlarged; c, vertical section of a fragment, magnified to show the internal structure. corniferous limestone, canada. (original.)] [illustration: fig. .--_cystiphyllum vesiculosum_, showing a succession of cups produces by budding from the original coral. of the natural size. devonian, america and europe. (original.)] [illustration: fig. --_zaphrentis cornicula_, of the natural size. devonian, america. (original.)] [illustration: fig. --_heliophyllum exiguum_, viewed from in front and behind. of the natural size. devonian, canada. (original.)] [illustration: fig. .--portion of a mass of _crepidophyllum archiaci_, of the natural size. hamilton formation, canada. (after billings.)] no true _graptolites_ have ever been detected in strata of devonian age; and the whole of this group has become extinguished--unless we refer here the still surviving _dictyonemoe_. the _coelenterates_, however, are represented by a vast number of _corals_, of beautiful forms and very varied types. the marbles of devonshire, the devonian limestones of the eifel and of france, and the calcareous strata of the corniferous and hamilton groups of america, are often replete with the skeletons of these organisms--so much so as to sometimes entitle the rock to be considered as representing an ancient coral-reef. in some instances the corals have preserved their primitive calcareous composition; and if they are embedded in soft shales, they may weather out of the rock in almost all their original perfection. in other cases, as in the marbles of devonshire, the matrix is so compact and crystalline that the included corals can only be satisfactorily studied by means of polished sections. in other cases, again, the corals have been more or less completely converted into flint, as in the corniferous limestone of north america. when this is the case, they often come, by the action of the weather, to stand out from the enclosing rock in the boldest relief, exhibiting to the observer the most minute details of their organization. as before, the principal representatives of the corals are still referable to the groups of the _rugosa_ and _tabulata_. amongst the rugose group we find a vast number of simple "cup-corals," generally known by the quarrymen as "horns," from their shape. of the many forms of these, the species of _cyathophyllum, heliophyllum_ (fig. ), _zaphrentis_ (fig. ), and _cystiphyllum_ (fig. ), are perhaps those most abundantly represented--none of these genera, however, except _heliophyllum_, being peculiar to the devonian period. there are also numerous compound rugose corals, such as species of _eridophyllum, diphyphyllum, syringopora, phillipsastroea_, and some of the forms of _cyathophyllum_ and _crepidophyllum_ (fig. ). some of these compound corals attain a very large size, and form of themselves regular beds, which have an analogy, at any rate, with existing coral-reefs, though there are grounds for believing that these ancient types differed from the modern reef-builders in being inhabitants of deep water. the "tabulate corals" are hardly less abundant in the devonian rocks than the _rugosa_; and being invariably compound, they hardly yield to the latter in the dimensions of the aggregations which they sometimes form. [illustration: fig. .--portion of a mass of _favosites gothlandica_, of the natural size. upper silurian and devonian of europe and america. (original.) billings.] [illustration: fig. .--fragment of _favosites hemispherica_, of the natural size. upper silurian and devonian of america. (after billings.)] the commonest, and at the same time the largest, of these are the "honeycomb corals," forming the genus _favosites_ (figs. , ), which derive both their vernacular and their technical names from their great likeness to masses of petrified honeycomb. the most abundant species are _favosites gothlandica_ and _f. hemispherica_, both here figured, which form masses sometimes not less than two or three feet in diameter. whilst _favosites_ has acquired a popular name by its honey-combed appearance, the resemblance of _michelinia_ to a fossilised wasp's nest with the comb exposed is hardly less striking, and has earned for it a similar recognition from the non-scientific public. in addition to these, there are numerous branching or plant-like tabulate corals, often of the most graceful form, which are distinctive of the devonian in all parts of the world. the _echinoderms_ of the devonian period call for little special notice. many of the devonian limestones are "crinoidal;" and the _crinoids_ are the most abundant and widely-distributed representatives of their class in the deposits of this period. the _cystideans_, with doubtful exceptions, have not been recognised in the devonian; and their place is taken by the allied group of the "pentremites," which will be further spoken of as occurring in the carboniferous rocks. on the other hand, the star-fishes, brittle-stars, and sea-urchins are all continued by types more or less closely allied to those of the preceding upper silurian. of the remains of ringed-worms (_annelides_), the most numerous and the most interesting are the calcareous envelopes of some small tube-inhabiting species. no one who has visited the seaside can have failed to notice the little spiral tubes of the existing _spirorbis_ growing attached to shells, or covering the fronds of the commoner sea weeds (especially _fucus serratus_). these tubes are inhabited by a small annelide, and structures of a similar character occur not uncommonly from the upper silurian upwards. in the devonian rocks, _spirorbis_ is an extremely common fossil, growing in hundreds attached to the outer surface of corals and shells, and appearing in many specific forms (figs. and ); but almost all the known examples are of small size, and are liable to escape a cursory examination. [illustration: fig. .--a, _spirobois omphalodes_, natural size and enlarged. devonian, europe and america; b, _spirorbis arkonensis_, of the natural size and enlarged; c, the same, with the tube twisted in the reverse direction. devonian, america. (onginal.)] [illustration: fig. . a b, _spirorbis laxus_, enlarged, upper silurian, america; c, _spirorbis spinulifera_, of the natural size and enlarged, devonian, canada. (after hall and the author.)] [illustration: fig. .--devonian trilobites; a, _phacops latifrons_, devonian of britain, the continent of europe, and south america; b, _homalonotus armatus_, europe; c, _phacops (trimerocephalus) loevis_, europe; d, head-shield of _phacops (portlockia) granulatus_, europe. (after salter and burmeister.)] the _crustaceans_ of the devonian are principally _eurypterids_ and _trilobites_. some of the former attain gigantic dimensions, and the quarrymen in the scotch old red give them the name of "seraphim" from their singular scale-like ornamentation. the _trilobites_, though still sufficiently abundant in some localites, have undergone a yet further diminution since the close of the upper silurian. in both america and europe quite a number of generic types have survived from the silurian, but few or no new ones make their appearance during this period in either the old world or the new. the _species_, however, are distinct; and the principal forms belong to the genera _phacops_ (fig. , a, c, d), _homalonotus_ (fig. , b), _proetus_, and _bronteus_. the species figured above under the name of _phacops latifrons_ (fig. , a), has an almost world-wide distribution, being found in the devonian of britain, belgium, france, germany, russia, spain, and south america; whilst its place is taken in north america by the closely-allied _phacops rana_. in addition to the _trilobites_, the devonian deposits have yielded the remains of a number of the minute _ostracoda_, such as _entomis_ ("_cypridina_"), _leperditia_, &c., which sometimes occur in vast numbers, as in the so-called "_cypridina_ slates" of the german devonian. there are also a few forms of _phyllopods_ (_estheria_). taken as a whole, the crustacean fauna of the devonian period presents many alliances with that of the upper silurian, but has only slight relationships with that of the lower carboniferous. besides _crustaceans_, we meet here for the first time with the remains of _air-breathing articulates_, in the shape of _insects_. so far, these have only been obtained from the devonian rocks of north america, and they indicate the existence of at least four generic types, all more or less allied to the existing may-flies (_ephemeridoe_). one of these interesting primitive insects, namely, _platephemera antiqua_ (fig. ), appears to have measured five inches in expanse of wing; and another (_xelloneura antiquorum_) has attached to its wing the remains of a "stridulating-organ" similar to that possessed by the modern grasshoppers--the instrument, as principal dawson remarks, of "the first music of living things that geology as yet reveals to us." [illustration: fig. .--wing of _platephemera antiqua_ devonian, america. (after dawson.)] amongst the _mollusca_, the devonian rocks have yielded a great number of the remains of sea-mosses (_polyzoa_). some of these belong to the ancient type _ptilodictya_, which seems to disappear here, or to the allied _clathropora_ (fig. ), with its fenestrated and reticulated fronds. we meet also with the graceful and delicate stems of _ceriopora_ (fig. ). [illustration: fig. .--fragment of _clathropora intertexta_, of the natural size and enlarged. devonian, canada. (original.)] [illustration: fig. .--fragment of _ceriopora hamiltonensis_, of the natural size and enlarged. devonian, canada. (original.)] [illustration: fig. .--fragment of _fenestella magnifica_, of the natural size and enlarged. devonian, canada. (original.)] [illustration: fig. .--fragment of _retepora phillipsi_, of the natural size and enlarged. devonian, canada. (original.)] [illustration: fig. .--fragment of _fenestella cribrosa_, of the natural size and enlarged. dovonian, canada. (original.)] the majority of the devonian _polyzoa_ belong, however, to the great and important palæozoic group of the lace-corals (_fenestella_, figs. and , _retepora_, fig. , _polypora_, and their allies). in all these forms there is a horny skeleton, of a fan-like or funnel-shaped form, which grew attached by its base to some foreign body. the frond consists of slightly-diverging or nearly parallel branches, which are either united by delicate cross-bars, or which bend alternately from side to side, and become directly united with one another at short intervals--in either case giving origin to numerous oval or oblong perforations, which communicate to the whole plant-like colony a characteristic netted and lace-like appearance. on one of its surfaces--sometimes the internal, sometimes the external--the frond carries a number of minute chambers or "cells," which are generally borne in rows on the branches, and of which each originally contained a minute animal. [illustration: fig. .--_spirifera sculptilis_. devonian, canada. (after billings.)] [illustration: fig. .--_spirifera mucronata_. devonian, america. (after billings.)] [illustration: fig. .--_atrypa reticularis_. upper silurian and devonian of europe and america. (after billings.)] the _brachiopods_ still continue to be represented in great force through all the devonian deposits, though not occurring in the true old red sandstone. besides such old types as _orthis, strophomena, lingula, athyris_, and _rhynchonella_, we find some entirely new ones; whilst various types which only commenced their existence in the upper silurian, now undergo a great expansion and development. this last is especially the case with the two families of the _spiriferidoe_ and the _produclidoe_. the _spirifers_, in particular, are especially characteristic of the devonian, both in the old and new worlds--some of the most typical forms, such as _spirifera mucronata_ (fig. ), having the shell "winged," or with the lateral angles prolonged to such an extent as to have earned for them the popular name of "fossil-butterflies." the closely-allied _spirifera disjunda_ occurs in britain, france, spain, belgium, germany, russia, and china. the family of the _productidoe_ commenced to exist in the upper silurian, in the genus _chonetes_, and we shall hereafter find it culminating in the carboniferous in many forms of the great genus _producta_[ ] itself. in the devonian period, there is an intermediate state of things, the genus _chonetes_ being continued in new and varied types, and the carboniferous _produdoe_ being represented by many forms of the allied group _productella_. amongst other well-known devonian brachiopods may be mentioned the two long-lived and persistent types _atrypa reticularis_ (fig. ) and _strophomena rhomboidalis_ (fig. ). the former of these commences in the upper silurian, but is more abundantly developed in the devonian, having a geographical range that is nothing less than world-wide; whilst the latter commences in the lower silurian, and, with an almost equally cosmopolitan range, survives into the carboniferous period. [footnote : the name of this genus is often written _productus_, just as _spirifera_ is often given in the masculine gender as _spirifer_ (the name originally given to it). the masculine termination to these names is, however, grammatically incorrect, as the feminine noun _cochlea_ (shell) is in these cases _understood_.] [illustration: fig. .--_strophomena rhomboidalis_. lower silurian, upper silurian, and devonian of europe and america.] [illustration: fig. .--different views of _platyceras dumosum_, of the natural size. devonian, canada. (original.)] the bivalves (_lamellibranchiata_) of the devonian call for no special comment, the genera _pterinea_ and _megalodon_ being, perhaps, the most noticeable. the univalves (_gasteropods_), also, need not be discussed in detail, though many interesting forms of this group are known. the type most abundantly represented, especially in america, is _platyceras_ (fig. ), comprising thin, wide-mouthed shells, probably most nearly allied to the existing "bonnet-limpets," and sometimes attaining very considerable dimensions. we may also note the continuance of the genus _euomphalus_, with its discoidal spiral shell. amongst the _heteropods_, the survival of _bellerophon_ is to be recorded; and in the "winged-snails," or _pteropods_, we find new forms of the old genera _tentaculites_ and _conularia_ (fig. ). the latter, with its fragile, conical, and often beautifully ornamented shell, is especially noticeable. [illustration: fig. .--_conularia ornata, of the natural size. devonian, europe.] [illustration: fig. .--_clymenia sedgwickii_. devonian, europe.] the remains of _cephalopoda_ are far from uncommon in the devonian deposits, all the known forms being still tetrabranchiate. besides the ancient types _orthoceras_ and _cyrtoceras_, we have now a predominance of the spirally-coiled chambered shells of _goniatites_ and _clymenia_. in the former of these the shell is shaped like that of the _nautilus_; but the partitions between the chambers ("septa") are more or less lobed, folded, or angulated, and the "siphuncle" runs along the _back_ or convex side of the shell--these being characters which approximate _goniatites_ to the true ammonites of the later rocks. in _clymenia_, on the other hand, whilst the shell (fig. ) is coiled into a flat spiral, and the partitions or septa are simple or only slightly lobed, there is still this difference, as compared with the _nautilus_, that the tube of the siphuncle is placed on the _inner_ or concave side of the shell. the species of _clymenia_ are exclusively devonian in their range; and some of the limestones of this period in germany are so richly charged with fossils of this genus as to have received the name of "clymenien-kalk." the sub-kingdom of the _vertebrates_ is still represented by _fishes_ only; but these are so abundant, and belong to such varied types, that the devonian period has been appropriately called the "age of fishes." amongst the existing fishes there are three great groups which are of special geological importance, as being more or less extensively represented in past time. these groups are: ( ) the _bony fishes_ (_teleostei_), comprising most existing fishes, in which the skeleton is more or less completely converted into bone; the tail is symmetrically lobed or divided into equal moieties; and the scales are usually thin, horny, flexible plates, which overlap one another to a greater or less extent. ( ) the _ganoid fishes_ (_ganoidei_), comprising the modern gar-pikes, sturgeons, &c., in which the skeleton usually more or less completely retains its primitive soft and cartilaginous condition; the tail is generally markedly unsymmetrical, being divided into two unequal lobes; and the scales (when present) have the form of plates of bone, usually covered by a layer of shining enamel. these scales may overlap; or they may be rhomboidal plates, placed edge to edge in oblique rows; or they have the form of large-sized bony plates, which are commonly united in the region of the head to form a regular buckler. ( ) the _placoid fishes_, or _elasmobranchii_, comprising the sharks, rays, and _chimoeroe_ of the present day, in which the skeleton is cartilaginous; the tail is unsymmetrically lobed; and the scales have the form of detached bony plates of variable size, scattered in the integument. it is to the two last of these groups that the devonian fishes belong, and they are more specially referable to the _ganoids_. the order of the ganoid fishes at the present day comprises but some seven or eight genera, the species of which principally or exclusively inhabit fresh waters, and all of which are confined to the northern hemisphere. as compared, therefore, with the bony fishes, which constitute the great majority of existing forms, the ganoids form but an extremely small and limited group. it was far otherwise, however, in devonian times. at this period, the bony fishes are not known to have come into existence at all, and the ganoids held almost undisputed possession of the waters. to what extent the devonian ganoids were confined to fresh waters remains yet to be proved; and that many of them lived in the sea is certain. it was formerly supposed that the old red sandstone of scotland and ireland, with its abundant fish-remains, might perhaps be a fresh-water deposit, since the habitat of its fishes is uncertain, and it contains no indubitable marine fossils. it has been now shown, however, that the marine devonian strata of devonshire and the continent of europe contain some of the most characteristic of the old red sandstone fishes of scotland; whilst the undoubted marine deposit of the corniferous limestone of north america contains numerous shark-like and ganoid fishes, including such a characteristic old red genus as _coccosleus_. there can be little doubt, therefore, but that the majority of the devonian fishes were truly marine in their habits, though it is probable that many of them lived in shallow water, in the immediate neighbourhood of the shore, or in estuaries. [illustration: fig. .--fishes of the devonian rocks of america. a, diagram of the jaws and teeth of _dinichthys hertzeri_, viewed from the front, and greatly reduced; b, diagram of the skull of _macropetalichthys sullivanti_, reduced in size; c, a portion of the enamelled surface of the skull of the same, magnified; d, one of the scales of _onychodus sigmoides_, of the natural size; e, one of the front teeth of the lower jaw of the same, of the natural size: f, fin-spine of _machoeracanthus major_, a shark-like fish, reduced in size. (after newberry.)] [illustration: fig. .--_cephalaspis lyellii_. old red sandstone, scotland. (after page.)] [illustration: fig. .--_pterichthys cornutus_. old red sandstone, scotland. (after agassiz.)] the devonian galloids belong to a number of groups; and it is only possible to notice a few of the most important forms here. the modern group of the sturgeons is represented, more or less remotely, by a few devonian fishes--such as _asterosteus_; and the great _macropetalichthys_ of the corniferous limestone of north america is believed by newberry to belong to this group. in this fish (fig. , b) the skull was of large size, its outer surface being covered with a tuberculated enamel; and, as in the existing sturgeons, the mouth seems to have been wholly destitute of teeth. somewhat allied, also, to the sturgeons, is a singular group of armoured fishes, which is highly characteristic of the devonian of britain and europe, and less so of that of america. in these curious forms the head and front extremity of the body were protected by a buckler composed of large enamelled plates, more or less firmly united to one another; whilst the hinder end of the body was naked, or was protected with small scales. some forms of this group--such as _pteraspis_ and _coccosteus_--date from the upper silurian; but they attain their maximum in the devonian, and none of them are known to pass upwards into the overlying carboniferous rocks. amongst the most characteristic forms of this group may be mentioned _cephalaspis_ (fig. ) and _pterichthys_ (fig. ). in the former of these the head-shield is of a crescentic shape, having its hinder angles produced backwards into long "horns," giving it the shape of a "saddler's knife." no teeth have been discovered; but the body was covered with small ganoid scales, and there was an unsymmetrical tail-fin. in _pterichthys_--which, like the preceding, was first brought to light by the labours of hugh miller--the whole of the head and the front part of the body were defended by a buckler of firmly-united enamelled plates, whilst the rest of the body was covered with small scales. the form of the "pectoral fins" was quite unique--these having the shape of two long, curved spines, somewhat like wings, covered by finely-tuberculated ganoid plates. all the preceding forms of this group are of small size; but few fishes, living or extinct, could rival the proportions of the great _dinichthys_, referred to this family by newberry. in this huge fish (fig. , a) the head alone is over three feet in length, and the body is supposed to have been twenty-five or thirty feet long. the head was protected by a massive cuirass of bony plates firmly articulated together, but the hinder end of the body seems to have been simply enveloped in a leathery skin. the teeth are of the most formidable description, consisting in both jaws of serrated dental plates behind, and in front of enormous conical tusks (fig. , a). though immensely larger, the teeth of _dinichthys_ present a curious resemblance to those of the existing mud-fishes (_lepidosiren_). in another great group of devonian ganoids, we meet with fishes more or less closely allied to the living _polypteri_ (fig. ) of the nile and senegal. in this group (fig. ) the pectoral fins consist of a central scaly lobe carrying the fin-rays on both sides, the scales being sometimes rounded and overlapping (fig. ), or more commonly rhomboidal and placed edge to edge (fig. , a). numerous forms of these "fringe-finned" ganoids occur in the devonian strata, such as _holoptychius, glyotoloemus, osteolepis, phaneropleuron_, &c. to this group is also to be ascribed the huge _onychodus_ (fig. , d and e), with its large, rounded, overlapping scales, an inch in diameter, and its powerful pointed teeth. it is to be remembered, however, that some of these "fringe-finned" ganoids are probably referable to the small but singular group of the "mud-fishes" (_dipnoi_), represented at the present day by the singular _lepidosiren_ of south america and africa, and the _ceratodus_ of the rivers of queensland. [illustration: fig. .--a, _polypterus_, a recent ganoid fish; b, _osteolepis_, a devonian ganoid; a a, pectoral fins, showing the fin-rays arranged round a central lobe.] [illusration: fig. .--_holoptychius nobilissimus_, restored. old red sandstone, scotland. a, scale of the same.] leaving the ganoid fishes, it still remains to be noticed that the devonian deposits have yielded the remains of a number of fishes more or less closely allied to the existing sharks, rays, and _chimoeroe_ (the _elasmobranchii_). the majority of the forms here alluded to are allied not to the true sharks and dog-fishes, but to the more peaceable "port jackson sharks," with their blunt teeth, adapted for crushing the shells of molluscs. the collective name of "cestracionts" is applied to these; and we have evidence of their past existence in the devonian seas both by their teeth, and by the defensive spines which were implanted in front of a greater or less number of the fins. these are bony spines, often variously grooved, serrated, or ornamented, with hollow bases, implanted in the integument, and capable of being erected or depressed at will. many of these "fin-spines" have been preserved to us in the fossil condition, and the devonian rocks have yielded examples belonging to many genera. as some of the true sharks and dog-fishes, some of the ganoids, and even some bony fishes, possess similar defences, it is often a matter of some uncertainty to what group a given spine is to be referred. one of these spines, belonging to the genus _machoeracanthus_, from the devonian rocks of america, has been figured in a previous illustration (fig. , f). in conclusion, a very few words may be said as to the validity of the devonian series as an independent system of rocks, preserving in its successive strata the record of an independent system of life. some high authorities have been inclined to the view that the devonian formation has in nature no actual existence, but that it is made up partly of beds which should be referred to the summit of the upper silurian, and partly of beds which properly belong to the base of the carboniferous. this view seems to have been arrived at in consequence of a too exclusive study of the devonian series of the british isles, where the physical succession is not wholly clear, and where there is a striking discrepancy between the organic remains of those two members of the series which are known as the "old red sandstone" and the "devonian" rocks proper. this discrepancy, however, is not complete; and, as we have seen, can be readily explained on the supposition that the one group of rocks presents us with the shallow water and littoral deposits of the period, while in the other we are introduced to the deep-sea accumulations of the same period. nor can the problem at issue be solved by an appeal to the phenomena of the british area alone, be the testimony of these what it may. as a matter of fact, there is at present no sufficient ground for believing that there is any irreconcilable discordance between the succession of rocks and of life in britain during the period which elapsed between the deposition of the upper ludlow and the formation of the carboniferous limestone, and the order of the same phenomena during the same period in other regions. some of the devonian types of life, as is the case with all great formations, have descended unchanged from older types; others pass upwards unchanged to the succeeding period: but the fauna and flora of the devonian period are, as a whole, quite distinct from those of the preceding silurian or the succeeding carboniferous; and they correspond to an equally distinct rock-system, which in point of time holds an intermediate position between the two great groups just mentioned. as before remarked, this conclusion may be regarded as sufficiently proved even by the phenomena of the british area; but it maybe said to be rendered a certainty by the study of the devonian deposits of the continent of europe--or, still more, by the investigation of the vast, for the most part uninterrupted and continuous series of sediments which commenced to be laid down in north america at the beginning of the upper silurian, and did not cease till, at any rate, the close of the carboniferous. literature. the following list comprises the more important works and memoirs to which the student of devonian rocks and fossils may refer:-- ( ) 'siluria.' sir roderick murchison. ( ) 'geology of russia in europe.' murchison (together with de verneuil and count von keyserling). ( ) "classification of the older rocks of devon and cornwall"--'proc. geol. soc.,' vol. iii., . sedgwick and murchison. ( ) "on the physical structure of devonshire;" and on the "classification of the older stratified rocks of devonshire and cornwall"--'trans. geol. soc.,' vol. v., . sedgwick and murchison. ( ) "on the distribution and classification of the older or palæozoic rocks of north germany and belgium"--'geol. trans.,' d ser., vol. vi., . sedgwick and murchison. ( ) 'report on the geology of cornwall, devon, and west somerset.' de la beche. ( ) 'memoirs of the geological survey of ireland and scotland.' jukes and geikie. ( ) "on the carboniferous slate (or devonian rocks) and the old red sandstone of south ireland and north devon"--'quart. journ. geol. soc.,' vol. xxii. jukes. ( ) "on the physical structure of west somerset and north devon;" and on the "palæontological value of devonian fossils"--'quart. journ. geol. soc.,' vol. iii. etheridge. ( ) "on the connection of the lower, middle, and upper old red sandstone of scotland"--'trans. edin. geol. soc.,' vol. i. part ii. powrie. ( ) 'the old red sandstone,' 'the testimony of the rocks,' and 'footprints of the creator.' hugh miller. ( ) "report on the th geological district"--'geology of new york,' vol. iv. james hall. ( ) 'geology of canada,' . sir w. e. logan. ( ) 'acadian geology.' dawson. ( ) 'manual of geology.' dana. ( ) 'geological survey of ohio,' vol. i. ( ) 'geological survey of illinois,' vol. i. ( ) 'palæozoic fossils of cornwall, devon, and west somerset.' phillips. ( ) 'recherches sur les poissons fossiles.' agassiz. ( ) 'poissous de l'old red.' agassiz. ( ) "on the classification of devonian fishes"--' mem. geol. survey of great britain,' decade x. huxley. ( ) 'monograph of the fishes of the old red sandstone of britain' (palæontographical society). powrie and lankester. ( ) 'fishes of the devonian system, palæontology of ohio.' newberry. ( ) 'monograph of british trilobites' (palæontographical society); salter. ( ) 'monograph of british merostomata' (palæontographical society). henry woodward. ( ) 'monograph of british brachiopoda' (palæontographical society). davidson. ( ) 'monograph of british fossil corals' (palæontographical society). milne-edwards and haime. ( ) 'polypiers foss. des terrains paléozoiques.' milne-edwards and jules haime. ( ) "devonian fossils of canada west"--'canadian journal,' new ser., vols. iv.-vi. billings. ( ) 'palæontology of new york,' vol. iv. james hall. ( ) 'thirteenth, fifteenth, and twenty-third annual reports on the state cabinet.' james hall. ( ) 'palæozoic fossils of canada,' vol. ii. billings. ( ) 'reports on the palæontology of the province of ontario for and .' nicholson. ( ) "the fossil plants of the devonian and upper silurian formations of canada"--'geol. survey of canada.' dawson. ( ) 'petrefacta germaniæ.' goldfuss. ( ) 'versteinerungen der grauwacken-formation.' &c. geinitz. ( ) 'beitrag zur palæontologie des thüringer-waldes.' richter and unger. ( ) 'ueber die placodermen der devonischen system.' pander. ( ) 'die gattungen der fossilen pflanzen.' goeppert. ( ) 'genera et species plantarum fossilium.' unger. chapter xii. the carboniferous period. overlying the devonian formation is the great and important series of the _carboniferous rocks_, so called because workable beds of coal are more commonly and more largely developed in this formation than in any other. workable coal-seams, however, occur in various other formations (jurassic, cretaceous, tertiary), so that coal is not an exclusively carboniferous product; whilst even in the coal-measures themselves the coal bears but a very small proportion to the total thickness of strata, occurring only in comparatively thin beds intercalated in a great series of sandstones, shales, and other genuine aqueous sediments. stratigraphically, the carboniferous rocks usually repose conformably upon the highest devonian beds, so that the line of demarcation between the carboniferous and devonian formations is principally a palæontological one, founded on the observed differences in the fossils of the two groups. on the other hand, the close of the carboniferous period seems to have been generally, though not universally, signalised by movements of the crust of the earth, so that the succeeding permian beds often lie unconformably upon the carboniferous sediments. strata of carboniferous age have been discovered in almost every large land-area which has been sufficiently investigated; but they are especially largely developed in britain, in various parts of the continent of europe, and in north america. their general composition, however, is, comparatively speaking, so uniform, that it will suffice to take a comprehensive view of the formation without considering any one area in detail, though in each region the subdivisions of the formation are known by distinctive local names. taking such a comprehensive view, it is found that the carboniferous series is generally divisible into a _lower_ and essentially calcareous group (the "sub-carboniferous" or "carboniferous limestone"); a _middle_ and principally arenaceous group (the "millstone grit"); and an upper group, of alternating shales and sandstones, with workable seams of coal (the "coal-measures"). i. the _carboniferous, sub-carboniferous_, or _mountain limestone series_ constitutes the general base of the carboniferous system. as typically developed in britain, the carboniferous limestone is essentially a calcareous formation, sometimes consisting of a mass of nearly pure limestone from to feet in thickness, or at other times of successive great beds of limestone with subordinate sandstones and shales. in the north of england the base of the series consists of pebbly conglomerates and coarse sandstones; and in scotland generally, the group is composed of massive sandstones with a comparatively feeble development of the calcareous element. in ireland, again, the base of the carboniferous limestone is usually considered to be formed by a locally-developed group of grits and shales (the "coomhola grits" and "carboniferous slate"), which attain the thickness of about feet, and contain an intermixture of devonian with carboniferous types of fossils. seeing that the devonian formation is generally conformable to the carboniferous, we need feel no surprise at this intermixture of forms; nor does it appear to be of great moment whether these strata be referred to the former or to the latter series. perhaps the most satisfactory course is to regard the coomhola grits and carboniferous slates as "passage-beds" between the devonian and carboniferous; but any view that may be taken as to the position of these beds, really leaves unaffected the integrity of the devonian series as a distinct life-system, which, on the whole, is more closely allied to the silurian than to the carboniferous. in north america, lastly, the sub-carboniferous series is never purely calcareous, though in the interior of the continent it becomes mainly so. in other regions, however, it consists principally of shales and sandstones, with subordinate beds of limestone, and sometimes with this beds of coal or deposits of clay-ironstone. ii. _the millstone grit_.--the highest beds of the carboniferous limestone series are succeeded, generally with perfect conformity, by a series of arenaceous beds, usually known as the _millstone grit_. as typically developed in britain, this group consists of hard quartzose sandstones, often so large-grained and coarse in texture as to properly constitute fine conglomerates. in other cases there are regular conglomerates, sometimes with shales, limestones, and thin beds of coal--the thickness of the whole series, when well developed, varying from to feet. in north america, the millstone grit rarely reaches feet in thickness; and, like its british equivalent, consists of coarse sandstones and grits, sometimes with regular conglomerates. whilst the carboniferous limestone was undoubtedly deposited in a tranquil ocean of considerable depth, the coarse mechanical sediments of the millstone grit indicate the progressive shallowing of the carboniferous seas, and the consequent supervention of shore-conditions. iii. _the coal-measures_.--the coal-measures properly so called rest conformably upon the millstone grit, and usually consist of a vast series of sandstones, shales, grits, and coals, sometimes with beds of limestone, attaining in some regions a total thickness of from to nearly , feet. beds of workable coal are by no means unknown in some areas in the inferior group of the sub-carboniferous; but the general statement is true, that coal is mostly obtained from the true coal-measures--the largest known, and at present most productive coal-fields of the world being in great britain, north america, and belgium. wherever they are found, with limited exceptions, the coal-measures present a singular _general_ uniformity of mineral composition. they consist, namely, of an indefinite alternation of beds of sandstone, shale, and coal, sometimes with bands of clay-ironstone or beds of limestone, repeated in no constant order, but sometimes attaining the enormous aggregate thickness of , feet, or little short of miles. the beds of coal differ in number and thickness in different areas, but they seldom or never exceed one-fiftieth part of the total bulk of the formation in thickness. the characters of the coal itself, and the way in which the coal-beds were deposited, will be briefly alluded to in speaking of the vegetable life of the period. in britain, and in the old world generally, the coal-measures are composed partly of genuine terrestrial deposits--such as the coal--and partly of sediments accumulated in the fresh or brackish waters of vast lagoons, estuaries, and marshes. the fossils of the coal-measures in these regions are therefore necessarily the remains either of terrestrial plants and animals, or of such forms of life as inhabit fresh or brackish waters, the occurrence of strata with marine fossils being quite a local and occasional phenomenon. in various parts of north america, on the other hand, the coal-measures, in addition to sandstones, shales, coal-seams, and bands of clay-ironstone, commonly include beds of limestone, charged with marine remains, and indicating marine conditions. the subjoined section (fig. ) gives, in a generalised form, the succession of the carboniferous strata in such a british area as the north of england, where the series is developed in a typical form. as regards the _life_ of the carboniferous period, we naturally find, as has been previously noticed, great differences in different parts of the entire series, corresponding to the different mode of origin of the beds. speaking generally, the lower carboniferous (or the sub-carboniferous) is characterised by the remains of marine animals; whilst the upper carboniferous (or coal-measures) is characterised by the remains of plants and terrestrial animals. in all those cases, however, in which marine beds are found in the series of the coal-measures, as is common in america, then we find that the fossils agree in their general characters with those of the older marine deposits of the period. [illustration: fig. . generalized section of the carboniferous strata of the north of england.] owing to the fact that coal is simply compressed and otherwise altered vegetable matter, and that it is of the highest economic value to man, the coal-measures have been more thoroughly explored than any other group of strata of equivalent thickness in the entire geological series. hence we have already a very extensive acquaintance with the _plants_ of the carboniferous period; and our knowledge on this subject is daily undergoing increase. it is not to be supposed, however, that the remains of plants are found solely in coal-measures; for though most abundant towards the summit, they are found in less numbers in all parts of the series. wherever found, they belong to the same great types of vegetation; but, before reviewing these, a few words must be said as to the origin and mode of formation of _coal_. the coal-beds, as before mentioned, occur interstratified with shales, sandstones, and sometimes limestones; and there may, within the limits of a single coal-field, be as many as or of such beds, placed one above the other at different levels, and varying in thickness from a few inches up to or feet. as a general rule, each bed of coal rests upon a bed of shale or clay, which is termed the "under-clay," and in which are found numerous roots of plants; whilst the strata immediately on the top of the coal may be shaly or sandy, but in either case are generally charged with the leaves and stems of plants, and often have upright trunks passing vertically through them. when we add to this that the coal itself is, chemically, nearly wholly composed of carbon, and that its microscopic structure shows it to be composed almost entirely of fragments of stems, leaves, bark, seeds, and vegetable _débris_ derived from _land-plants_, we are readily enabled to understand how the coal was formed. the "_under-clay_" immediately beneath the coal-bed represents an old land-surface--sometimes, perhaps, the bottom of a swamp or marsh, covered with a luxuriant vegetation; the _coal bed_ itself represents the slow accumulation, through long periods, of the leaves, seeds, fruits, stems, and fallen trunks of this vegetation, now hardened and compressed into a fraction of its original bulk by the pressure of the superincumbent rocks; and the strata of sand or shale above the coal-bed--the so-called "roof" of the coal--represent sediments quietly deposited as the land, after a long period of repose, commenced to sink beneath the sea. on this view, the rank and long-continued vegetation which gave rise to each coal-bed was ultimately terminated by a slow depression of the surface on which the plants grew. the land-surface then became covered by the water, and aqueous sediments were accumulated to a greater or less thickness upon the dense mass of decaying vegetation below, enveloping any trunks of trees which might still be in an erect position, and preserving between their layers the leaves and branches of plants brought down from the neighbouring land by streams, or blown into the wafer by the wind. finally, there set in a slow movement of elevation,--the old land again reappeared above the water; a new and equally luxuriant vegetation flourished upon the new land-surface; and another coal-bed was accumulated, to be preserved ultimately in a similar fashion. some few beds of coal may have been formed by drifted vegetable matter brought down into the ocean by rivers, and deposited directly on the bottom of the sea; but in the majority of cases the coal is undeniably the result of the slow growth and decay of plants _in situ_: and as the plants of the coal are not _marine_ plants, it is necessary to adopt some such theory as the above to account for the formation of coal-seams. by this theory, as is obvious, we are compelled to suppose that the vast alluvial and marshy flats upon which the coal-plants grew were liable to constantly-recurring oscillations of level, the successive land-surfaces represented by the successive coal-beds of any coal-field being thus successively buried beneath accumulations of mud or sand. we have no need, however, to suppose that these oscillations affected large areas at the same time; and geology teaches us that local elevations and depressions of the land have been matters of constant occurrence throughout the whole of past time. all the varieties of coal (bituminous coal, anthracite; cannel-coal, &c.) show a more or less distinct "lamination"--that is to say, they are more or less obviously composed of successive thin layers, differing slightly in colour and texture. all the varieties of coal, also, consist chemically of _carbon_, with varying proportions of certain gaseous constituents and a small amount of incombustible mineral or "ash." by cutting thin and transparent slices of coal, we are further enabled, by means of the microscope, to ascertain precisely not only that the carbon of the coal is derived from vegetables, but also, in many cases, what kinds of plants, and what parts of these, enter into the formation of coal. when examined in this way, all coals are found to consist more or less entirely of vegetable matter; but there is considerable difference in different coals as to the exact nature of this. by professor huxley it has been shown that many of the english coals consist largely of accumulations of rounded discoidal sacs or bags, which are unquestionably the seed-vessels or "spore-cases" of certain of the commoner coal-plants (such as the _lepidodendra_). the best bituminous coals seem to be most largely composed of these spore-cases; whilst inferior kinds possess a progressively increasing amount of the dull carbonaceous substance which is known as "mineral charcoal," and which is undoubtedly composed of "the stems and leaves of plants reduced to little more than their carbon." on the other hand, principal dawson finds that the american coals only occasionally exhibit spore-cases to any extent, but consist principally of the cells, vessels, and fibres of the bark, integumentary coverings, and woody portions of the carboniferous plants. the number of plants already known to have existed during the carboniferous period is so great, that nothing more can be done here than to notice briefly the typical and characteristic _groups_ of these--such as the ferns, the calamites, the lepidodendroids, the sigillarioids, and the conifers. [illustration: fig. .--_odontopteris schlotheimii_. carboniferous, europe and north america.] [illustration: fig. .--_calamites cannoeformis_. carboniferous rocks, europe and north america.] in accordance with m. brongniart's generalisation, that the palæozoic period is, botanically speaking, the "age of acrogens," we find the carboniferous plants to be still mainly referable to the flowerless or "cryptogamous" division of the vegetable kingdom. the flowering or "phanerogamous" plants, which form the bulk of our existing vegetation, are hardly known, with certainty, to have existed at all in the carboniferous era, except as represented by trees related to the existing pines and firs, and possibly by the cycads or "false palms."[ ] amongst the "cryptogams," there is no more striking or beautiful group of carboniferous plants than the _ferns_. remains of these are found all through the carboniferous, but in exceptional numbers in the coal-measures, and include both herbaceous forms like the majority of existing species, and arborescent forms resembling the living tree-ferns of new zealand. amongst the latter, together with some new types, are examples of the genera _psaronius_ and _caulopteris_, both of which date from the devonian. the simply herbaceous ferns are extremely numerous, and belong to such widely-distributed and largely-represented genera as _neuropteris, odontopteris_ (fig. ), _alethopteris, pecopteris, sphenopteris, hymenophyllites_, &c. [footnote : whilst the vegetation of the coal-period was mainly a terrestrial one, aquatic plants are not unknown. sea-weeds (such as the _spirophyton cauda-galli_) are common in some of the marine strata; whilst coal, according to the researches of the abbé castracane, is asserted commonly to contain the siliceous envelopes of diatoms.] the fossils known as _calamites_ (fig. ) are very common in the carboniferous deposits, and have given occasion to an abundance of research and speculation. they present themselves as prostrate and flattened striated stems, or as similar uncompressed stems growing in an erect position, and sometimes attaining a length of twenty feet or more. externally, the stems are longitudinally ribbed, with transverse joints at regular intervals, these joints giving origin to a whorl or branchlets, which mayor may not give origin to similar whorls of smaller branchlets still. the stems, further, were hollow, with transverse partitions at the joints, and having neither true wood nor bark, but only a thin external fibrous shell. there can be little doubt but that the _calamites_ are properly regarded as colossal representatives of the little horse-tails (_equisetaceoe_) of the present day. they agree with these not only in the general details of their organisation, but also in the fact that the fruit was a species of cone, bearing "spore-cases" under scales. according to principal dawson, the _calamites_ "grew in dense brakes on the sandy and muddy flats, subject to inundation, or perhaps even in water; and they had the power of budding out from the base of the stem, so as to form clumps of plants, and also of securing their foothold by numerous cord-like roots proceeding from various heights on the lower part of the stem." [illustration: fig. .--_lepidodendron sternbergii_, carboniferous, europe. the central figure represents a portion of the trunk with its branches, much reduced in size. the right-hand figure is a portion of a branch with the leaves partially attached to it; and the left-hand figure represents the end of a branch bearing a cone of fructification.] the _lepidodendroids_, represented mainly by the genus _lepidodendron_ itself (fig. ), were large tree-like plants, which attain their maximum in the carboniferous period, but which appear to commence in the upper silurian, are well represented in the devonian, and survive in a diminished form into the permian. the trunks of the larger species of _lepidodendron_ at times reach a length of fifty feet and upwards, giving off branches in a regular bifurcating manner. the bark is marked with numerous rhombic or oval scars, arranged in quincunx order, and indicating the points where the long, needle-shaped leaves were formerly attached. the fruit consisted of cones or spikes, carried at the ends of the branches, and consisting of a central axis surrounded by overlapping scales, each of which supports a "spore-case" or seed-vessel. these cones have commonly been described under the name of _lepidostrobi_. in the structure of the trunk there is nothing comparable to what is found in existing trees, there being a thick bark surrounding a zone principally composed of "scalariform" vessels, this in turn enclosing a large central pith. in their general appearance the _lepidodendra_ bring to mind the existing araucarian pines; but they are true "cryptogams," and are to be regarded as a gigantic extinct type of the modern club-mosses (_lycopodiaceoe_). they are amongst the commonest and most characteristic of the carboniferous plants; and the majority of the "spore-cases" so commonly found in the coal appear to have been derived from the cones of lepidodendroids. the so-called _sigillanoids_, represented mainly by _sigillaria_ itself (fig. ), were no less abundant and characteristic of the carboniferous forests than the _lepidodendra_. they commence their existence, so far as known, in the devonian period, but they attain their maximum in the carboniferous; and--unlike the lepidodendroids--they are not known to occur in the permian period. they are comparatively gigantic in size, often attaining a height of from thirty to fifty feet or more; but though abundant and well preserved, great divergence of opinion prevails as to their true affinities. the _name_ of sigillarioids (lat. _sigilla_, little seals or images) is derived from the fact that the bark is marked with seal-like impressions or leaf-scars (fig. ). [illustration: fig. .--fragment of the external surface of _sigillaria groeseri_, showing the ribs and leaf-scars. the left-hand figure represents a small portion enlarged. carboniferous, europe.] externally, the trunks of _sigillaria_ present strong longitudinal ridges, with vertical alternating rows of oval leaf-scars indicating the points where the leaves were originally attached. the trunk was furnished with a large central pith, a thick outer bark, and an intermediate woody zone,--composed, according to dawson, partly of the disc-bearing fibres so characteristic of conifers; but, according to carruthers, entirely made up of the "scalariform" vessels characteristic of cryptogams. the size of the pith was very great, and the bark seems to have been the most durable portion of the trunk. thus we have evidence that in many cases the stumps and "stools" of _sigillarioe_, standing upright in the old carboniferous swamps, were completely hollowed out by internal decay, till nothing but an exterior shell of bark was left. often these hollow stumps became ultimately filled up with sediment, sometimes enclosing the remains of galley-worms, land-snails, or amphibians, which formerly found in the cavity of the trunk a congenial home; and from the sandstone or shale now filling such trunks some of the most interesting fossils of the coal-period have been obtained. there is little certainty as to either the leaves or fruits of _sigillaria_, and there is equally little certainty as to the true botanical position of these plants. by principal dawson they are regarded as being probably flowering plants allied to the existing "false palms" or "_cycads_," but the high authority of mr carruthers is to be quoted in support of the belief that they are cryptogamic, and most nearly allied to the club-mosses. [illustration: fig. .--_stigmaria ficoides_. quarter natural size. carboniferous.] leaving the botanical position of _sigillaria_ thus undecided, we find that it is now almost universally conceded that the fossils originally described under the name of _stigmaria_ are the _roots_ of _sigillaria_, the actual connection between the two having been in numerous instances demonstrated in an unmistakable manner. the _stigmarioe_ (fig. ) ordinarily present themselves in the form of long, compressed or rounded fragments, the external surface of which is covered with rounded pits or shallow tubercles, each of which has a little pit or depression in its centre. from each of these pits there proceeds, in perfect examples, a long cylindrical rootlet; but in many cases these have altogether disappeared. in their internal structure, _stigmaria_ exhibits a central pith surrounded by a sheath of scalariform vessels, the whole enclosed in a cellular envelope. the _stigmarioe_ are generally found ramifying in the "under-clay," which forms the floor of a bed of coal, and which represents the ancient soil upon which the _sigillarioe_ grew. [illustration: fig. .--_trigonocarpon ovatum_. coal-measures, britain. (after liudley and hutton.)] the _lepidodendroids and sigillaroids, though the first were certainly, and the second possibly, cryptogamic or flowerless plants, must have constituted the main mass of the forests of the coal period; but we are not without evidence of the existence at the same time of genuine "trees," in the technical sense of this term--namely, flowering plants with large woody stems. so far as is certainly known, all the true trees of the carboniferous formation were _conifers_, allied to the existing pines and firs. they are recognised by the great size and concentric woody rings of their prostrate, rarely erect trunks, and by the presence of disc-bearing fibres in their wood, as demonstrated by the microscope; and the principal genera which have been recognised are _dadoxylon, paloeoxylon, araucarioxylon_, and _pinites_. their fruit is not known with absolute certainty, unless it be represented, as often conjectured, by _trigonocarpon_ (fig. ). the fruits known under this name are nut-like, often of considerable size, and commonly three- or six-angled. they probably originally possessed a fleshy envelope; and if truly referable to the _conifers_, they would indicate that these ancient evergreens produced berries instead of cones, and thus resembled the modern yews rather than pines. it seems, further, that the great group of the _cycads_, which are nearly allied to the _conifers_, and which attained such a striking prominence in the secondary period, probably commenced its existence during the coal period; but these anticipatory forms are comparatively few in number, and for the most part of somewhat dubious affinities. chapter xiii. the carboniferous period--continued. animal life of the carboniferous. we have seen that there exists a great difference as to the mode of origin of the carboniferous sediments, some being purely marine, whilst others are terrestrial; and others, again, have been formed in inland swamps and morasses, or in brackish-water lagoons, creeks, or estuaries. a corresponding difference exists necessarily in the animal remains of these deposits, and in many regions this difference is extremely well marked and striking. the great marine limestones which characterise the lower portion of the carboniferous series in britain, europe, and the eastern portion of america, and the calcareous beds which are found high up in the carboniferous in the western states of america, may, and do, often contain the remains of drifted plants; but they are essentially characterised by marine fossils; and, moreover, they can be demonstrated by the microscope to be almost wholly composed of the remains of animals which formerly inhabited the ocean. on the other hand, the animal remains of the beds accompanying the coal are typically the remains of air-breathing, terrestrial, amphibious, or aerial animals, together with those which inhabit fresh or brackish waters. marine fossils may be found in the coal-measures, but they are invariably confined to special horizons in the strata, and they indicate temporary depressions of the land beneath the sea. whilst the distinction here mentioned is one which cannot fail to strike the observer, it is convenient to consider the animal life of the carboniferous as a whole: and it is simply necessary, in so doing, to remember that the marine fossils are in general derived from the inferior portion of the system; whilst the air-breathing, fresh-water, and brackish-water forms are almost exclusively derived from the superior portion of the same. [illustration: fig. .--transparent slice of carboniferous limestone, from spergen hill, indiana, u.s., showing numerous shells of _endothyra_ (_rotalia_), _baiteyi_ slightly enlarged. (original.)] [illustration: fig. .--_fusulina cylindrica_, carboniferous limestone, russia.] the carboniferous _protozoans_ consist mainly of _foraminifera_ and _sponges_. the latter are still very insufficiently known, but the former are very abundant, and belong to very varied types. thin slices of the limestones of the period, when examined by the microscope, very commonly exhibit the shells of _foraminifera_ in greater or less plenty. some limestones, indeed, are made up of little else than these minute and elegant shells, often belonging to types, such as the textularians and rotalians, differing little or not at all from those now in existence. this is the case, for example, with the carboniferous limestone of spergen hill in indiana (fig. ), which is almost wholly made up of the spiral shells of a species of _endothyra_. in the same way, though to a less extent, the black carboniferous marbles of ireland, and the similar marbles of yorkshire, the limestones of the west of england and of derbyshire, and the great "scar limestones" of the north of england, contain great numbers of foraminiferous shells; whilst similar organisms commonly occur in the shale-beds associated with the limestones throughout the lower carboniferous series. one of the most interesting of the british carboniferous forms is the _saccammina_ of mr henry brady, which is sometimes present in considerable numbers in the limestones of northumberland, cumberland, and the west of scotland, and which is conspicuous for the comparatively large size of its spheroidal or pear-shaped shell (reaching from an eighth to a fifth of an inch in size). more widely distributed are the generally spindle-shaped shells of _fusulina_ (fig. ), which occur in vast numbers in the carboniferous limestone of russia, armenia, the southern alps, and spain, similar forms occurring in equal profusion in the higher limestones which are found in the coal-measures of the united states, in ohio, illinois, indiana, missouri, &c. mr henry brady, lastly, has shown that we have in the _nummulina pristina_ of the carboniferous limestone of namur a genuine _nummulite_, precursor of the great and important family of the tertiary nummulites. [illustration: fig. --corals of the carboniferous limestone. a. _cyathophyllum paracida_, showing young corallites budded forth from the disc of the old one; a', one of the corallites of the same, seen in cross-section; b, fragment of a mass of _lithostrotion irregulare_; b', one of the corallites of the same, divided transversely; c, portion of the simple cylindrical coral of _amplexus coralloides_; c', transverse section of the same species; d, _zaphrentis vermicularis_, showing the depression or "fossula" on one side of the cup; e, fragrent of a mass of _syringopora ramulosa_; f, fragment of _coetetes tumidus_; f', portion of the same of the same, enlarged. from the carboniferous limestone of britain and belgium. (after thomson, de koninck, milne-edwards and haime, and the author.)] the sub-kingdom of the _coelenterates_, so far as certainly known, is represented only by _corals_;[ ] but the remains of these are so abundant in many of the limestones of the carboniferous formation as to constitute a feature little or not at all less conspicuous than that afforded by the crinoids. as is the case in the preceding period, the corals belong, almost exclusively, to the groups of the _rugosa_ and _tabulata_; and there is a general and striking resemblance and relationship between the coral-fauna of the devonian as a whole, and that of the carboniferous. nevertheless, there is an equally decided and striking amount of difference between these successive faunas, due to the fact that the great majority of the carboniferous _species_ are new; whilst some of the most characteristic devonian _genera_ have nearly or quite disappeared, and several new genera now make their appearance for the first time. thus, the characteristic devonian types _heliophyllum, pachyphyllum, chonophyllum, acervularia, spongophyllum, smithia, endophyllum_, and _cystiphyllum_, have now disappeared; and the great masses of _favosites_ which are such a striking feature in the devonian limestones, are represented but by one or two degenerate and puny successors. on the other hand, we meet in the carboniferous rocks not only with entirely new genera--such as _axophyllum, lophophyllum_, and _londsdaleia_--but we have an enormous expansion of certain types which had just begun to exist in the preceding period. this is especially well seen in the case of the genus _lithostrotion_ (fig. , b), which more than any other may be considered as the predominant carboniferous group of corals. all the species of _lithostrotion_ are compound, consisting either of bundles of loosely-approximated cylindrical stems, or of similar "coral-lites" closely aggregated together into astræiform colonies, and rendered polygonal by mutual pressure. this genus has a historical interest, as having been noticed as early as in the year by edward lhwyd; and it is geologically important from its wide distribution in the carboniferous rocks of both the old and new worlds. many species are known, and whole beds of limestone are often found to be composed of little else than the skeletons of these ancient corals, still standing upright as they grew. hardly less characteristic of the carboniferous than the above is the great group of simple "cup-corals," of which _clisiophyllum_ is the central type. amongst types which commenced in the silurian and devonian, but which are still well represented here, may be mentioned _syringopora_ (fig. , e), with its colonies of delicate cylindrical tubes united at intervals by cross-bars; _zaphrentis_ (fig. , d), with its cup-shaped skeleton and the well-marked depression (or "fossula") on one side of the calice; _amplexus_ (fig. , c), with its cylindrical, often irregularly swollen coral and short septa; _cyathophyllum_ (fig. , a), sometimes simple, sometimes forming great masses of star-like corallites; and _choetetes_, with its branched stems, and its minute, "tabulate" tubes (fig. , f). the above, together with other and hardly less characteristic forms, combine to constitute a coral-fauna which is not only in itself perfectly distinctive, but which is of especial interest, from the fact that almost all the varied types of which it is composed disappeared utterly before the close of the carboniferous period. in the first marine sediments of a calcareous nature which succeeded to the coal-measures (the magnesian limestones of the permian), the great group of the _rugose corals_, which flourished so largely throughout the silurian, devonian, and carboniferous periods, is found to have all but disappeared, and it is never again represented save sporadically and by isolated forms. [footnote : a singular fossil has been described by professor martin duncan and mr jenkins from the carboniferous rocks under the name of _paloeocoryne_, and has been referred to the hydroid zoophytes (_corynida_). doubt, however, has been thrown by other observers on the correctness of this reference.] [illustration: fig. .--_platycrinus tricontadactylus_, lower carboniferous. the left-hand figure shows the calyx, arms, and upper part of the stem; and the figure next this shows the surface of one of the joints of the column. the right-hand figure shows the proboscis. (after m'coy.)] [illustration: fig. .--a, _pentremites pyriformis_, side-view of the body ("calyx"); b, the same viewed from below, showing the arrangement of the plates; c, body of _pentremites conoideus_, viewed from above. carboniferous.] amongst the _echinoderms_, by far the most important forms are the sea-lilies and the sea-urchins--the former from their great abundance, and the latter from their singular structure; but the little group of the "pentremites" also requires to be noticed. the sea-lilies are so abundant in the carboniferous rocks, that it has been proposed to call the earlier portion of the period the "age of crinoids." vast masses of the limestones of the period are "crinoidal," being more or less extensively composed of the broken columns, and detached plates and joints of sea-lilies, whilst perfect "heads" may be exceedingly rare and difficult to procure. in north america the remains of crinoids are even more abundant at this horizon than in britain, and the specimens found seem to be commonly more perfect. the commonest of the carboniferous crinoids belong to the genera _cyathocrinus, actinocrinus, platycrinus_, (fig. ), _poteriocrinus, zeacrinus_, and _forbesiocrinus_. closely allied to the crinoids, or forming a kind of transition between these and the cystideans, is the little group of the "pentremites," or _blastoids_ (fig. ). this group is first known to have commenced its existence in the upper silurian, and it increased considerably in numbers in the devonian; but it was in the seas of the carboniferous period that it attained its maximum, and no certain representative of the family has been detected in any later deposits. the "pentremites" resemble the crinoids in having a cup-shaped body (fig. , a) enclosed by closely-fitting calcareous plates, and supported on a short stem or "column," composed of numerous calcareous pieces flexibly articulated together. they differ from the crinoids, however, in the fact that the upper surface of the body does not support the crown of branched feathery "arms," which are so characteristic of the latter. on the contrary, the summit of the cup is closed up in the fashion of a flower-bud, whence the technical name of _blastoidea_ applied to the group (gr. _blastos_, a bud; _eidos_, form). from the top of the cup radiate five broad, transversely-striated areas (fig. , c), each with a longitudinal groove down its middle; and along each side of each of these grooves there seems to have been attached a row of short jointed calcareous filaments or "pinnules." [illustration: fig. .--_paloechinus ellipticus_, one of the carboniferous sea-urchins. the left-hand figure shows one of the "ambulacral areas" enlarged, exhibiting the perforated plates. the right-land figure exhibits a single plate from one of the "inter-ambulacral areas." (after m'coy.)] a few star-fishes and brittle-stars are known to occur in the carboniferous rocks; but the only other echinodemls of this period which need be noticed are the sea-urchins (_echinoids_). detached plates and spines of these are far from rare in the carboniferous deposits; but anything like perfect specimens are exceedingly scarce. the carboniferous sea-urchins agree with those of the present day in having the body enclosed in a shell formed by an enormous number of calcareous plates articulated together. the shell may be regarded as, typically, nearly spherical in shape, with the mouth in the centre of the base, and the excretory opening or vent at its summit. in both the ancient forms and the recent ones, the plates of the shell are arranged in ten zones which generally radiate from the summit to the centre of the base. in five of these zones--termed the "ambulacral areas"--the plates are perforated by minute apertures or "pores," through which the animal can protrude the little water-tubes ("tube-feet") by which its locomotion is carried on. in the other five zones--the so-called "inter-ambulacral areas"--the plates are of larger size, and are not perforated by any apertures. in all the modern sea-urchins each of these ten zones, whether perforate or imperforate, is composed of two rows of plates; and there are thus twenty rows of plates in all. in the palæozoic sea-urchins, on the other hand, the "ambulacral areas" are often like those of recent forms, in consisting of _two_ rows of perforated plates (fig. ); but the "inter-ambulacral areas" are always quite peculiar in consisting each of three, four, five, or more rows of large imperforate plates, whilst there are sometimes four or ten rows of plates in the "ambulacral areas" also: so that there are many more than twenty rows of plates in the entire shell. some of the palæozoic sea-urchins, also, exhibit a very peculiar singularity of structure which is only known to exist in a very few recently-discovered modern forms (viz., _calveria_ and _phormosoma_). the plates of the inter-ambulacral areas, namely, overlap one another in an imbricating manner, so as to communicate a certain amount of flexibility to the shell; whereas in the ordinary living forms these plates are firmly articulated together by their edges, and the shell forms a rigid immovable box. the carboniferous sea-urchins which exhibit this extraordinary peculiarity belong to the genera _lepidechinus_ and _lepidesthes_, and it seems tolerably certain that a similar flexibility of the shell existed to a less degree in the much more abundant genus _archoeocidaris_. the carboniferous sea-urchins, like the modern ones, possessed movable spines of greater or less length, articulated to the exterior of the shell; and these structures are of very common occurrence in a detached condition. the most abundant genera are _archoeocidaris_ and _paloechinus_; but the characteristic american forms belong principally to _melonites, oligoporus_, and _lepidechinus_. [illustration: fig. .--_spirorbis (microconchus) carbonarius_, of the natural size, attached to a fossil plant, and magnified. carboniferous britain and north america. (after dawson.)] amongst the _annelides_ it is only necessary to notice the little spiral tubes of _spirorbis carbonarius_ (fig. ), which are commonly found attached to the leaves or stems of the coal-plants. this fact shows that though the modern species of _spirorbis_ are inhabitants of the sea, these old representatives of the genus must have been capable of living in the brackish waters of lagoons and estuaries. [illustration: fig. .--_prestwichia rotundata_, a limuloid crustacean. coal-measures, britain. (after henry woodward.)] [illustration: fig. .--crustaceans of the carboniferous rocks. a, _phillipsia seminifera_, of the natural size--mountain limestone, europe; b, one valve of the shell of _estheria tenella_, of the natural size and enlarged--coal-measures, europe; c, bivalved shell of _entomoconchus scouleri_, of the natural size--mountain limestone, europe; d, _dithyrocaris scouleri_, reduced in size--mountain limestone, ireland; e, _paloeocaris typus_, slightly enlarged--coal-measures, north america; f, _anthrapaloemon gracilis_, of the natural size--coal-measures, north america. (after de koninck, m'coy, rupert jones, and meek and worthen.)] the _crustaceans_ of the carboniferous rocks are numerous, and belong partly to structural types with which we are already familiar, and partly to higher groups which come into existence here for the first time. the gigantic _eurypterids_ of the upper silurian and devonian are but feebly represented, and make their final exit here from the scene of life. their place, however, is taken by peculiar forms belonging to the allied group of the _xiphosura_, represented at the present day by the king-crabs or "horse-shoe crabs" (_limulus_). characteristic forms of this group appear in the coal-measures both of europe and america; and though constituting three distinct genera (_prestwichia, belinurus_, and _euproöps_), they are all nearly related to one another. the best known of them, perhaps, is the _prestwichia rotundala_ of coalbrookdale, here figured (fig. ). the ancient and formerly powerful order of the _trilobites_ also undergoes its final extinction here, not surviving the deposition of the carboniferous limestone series in europe, but extending its range in america into the coal-measures. all the known carboniferous forms are small in size and degraded in point of structure, and they are referable to but three genera (_phillipsia, griffithides_, and _brachymetopus_), belonging to a single family. the _phillipsia seminifera_ here figured (fig. , a) is a characteristic species in the old world. the water-fleas (_ostracoaa_) are extremely abundant in the carboniferous rocks, whole strata being often made up of little else than the little bivalved shells of these crustaceans. many of them are extremely small, averaging about the size of a millet-seed; but a few forms, such as _entomoconchus scouleni_ (fig. , c), may attain a length of from one to three quarters of an inch. the old group of the _phyllopods_ is is likewise still represented in some abundance, partly by tailed forms of a shrimp-like appearance, such as _dithyrocaris_ (fig. , d), and partly by the curious striated _estherioe_ and their allies, which present a curious resemblance to the true bivalve molluscs (fig. , b). lastly, we meet for the first time in the carboniferous rocks with the remains of the highest of all the groups of _crustaceans_--namely, the so-called "decapods," in which there are five pairs of walking-limbs, and the hinder end of the body ("abdomen") is composed of separate rings, whilst the anterior end is covered by a head-shield or "carapace." all the carboniferous decapods hitherto discovered resemble the existing lobsters, prawns, and shrimps (the _macrura_), in having a long and well-developed abdomen terminated by an expanded tail-fin. the _paloeocaris typus_ (fig. , e) and the _anthrapaloemon gracilis_ (fig. , f), from the coal-measures of illinois, are two of the best understood and most perfectly preserved of the few known representatives of the "long-tailed" decapods in the carboniferous series. the group of the crabs or "short-tailed" decapods (_brachyura_), in which the abdomen is short, not terminated by a tail-fin, and tucked away out of sight beneath the body, is at present not known to be represented at all in the carboniferous deposits. [illustration: fig. .--_cyclophthalmus senior_. a fossil scorpion from the coal-measures of bohemia.] [illustration: fig. .--_xylobius sigillarioe_, a carboniferous myriapod. a, a specimen, of the natural size; b, anterior portion of the same, enlarged; c, posterior portion, enlarged. from the coal-measures of nova scotia. (after dawson.)] [illustration: fig. --_haplophlebium barnesi_, a carboniferous insect, from the coal-meastures of nova scotia. (after dawson.)] in addition to the water-inhabiting group of the crustaceans, we find the articulate animals to be represented by members belonging to the air-breathing classes of the _arachnida, myriapoda_, and _insecta_. the remains of these, as might have been expected, are not known to occur in the marine limestones of the carboniferous series, but are exclusively found in beds associated with the coal, which have been deposited in lagoons, estuaries, or marshes, in the immediate vicinity of the land, and which actually represent an old land-surface. the _arachnids_ are at present the oldest known of their class, and are represented both by true spiders and scorpions. remains of the latter (fig. ) have been found both in the old and new worlds, and indicate the existence in the carboniferous period of scorpions differing but very little from existing forms. the group of the _myriapoda_, including the recent centipedes and galley-worms, is likewise represented in the carboniferous strata, but by forms in many respects very unlike any that are known to exist at the present day. the most interesting of these were obtained by principal dawson, along with the bones of amphibians and the shells of land-snails, in the sediment filling the hollow trunks of _sigillaria_, and they belong to the genera _xylobius_ (fig. ) and archiulus. lastly, the true _insects_ are represented by various forms of beetles (_coleoptera_), _orthoptera_ (such as cockroaches), and _neuropterous_ insects resembling those which we have seen to have existed towards the close of the devonian period. one of the most remarkable of the latter is a huge may-fly (_haplophlebium barnesi_, fig. ), with netted wings attaining an expanse of fully seven inches, and therefore much exceeding any existing ephemerid in point of size. [illustration: fig. .--carboniferous _polyzoa_. a, fragment of _polypora dendroides_, of the natural size, ireland; a' small portion of the same, enlarged to show the cells; b, glauconome pulcherrima_, a fragment, of the natural size, ireland; b', portion of the same, enlarged; c, the central screw-like axis of _archimedes wortheni_, of the natural size--carboniferous, america; c', portion of the exterior of the frond of the same, enlarged; c'', portion of the interior of the frond of the same showing the mouths of the cells, enlarged. (after m'coy and hall.)] the lower groups of the _mollusca_ are abundantly represented in the marine strata of the carboniferous series by _polyzoans_ and _brachiopods_. amongst the former, although a variety of other types are known, the majority still belong to the old group of the "lace-corals" (_fenestellidoe_), some of the characteristic forms of which are here figured (fig. ). the graceful netted fronds of _fenestella, retepora_, and _polypora_ (fig. , a) are highly characteristic, as are the slender toothed branches of _glauconome_ (fig. , b). a more singular form, however, is the curious _archimedes_ (fig. , c), which is so characteristic of the carboniferous formation of north america. in this remarkable type, the colony consists of a succession of funnel-shaped fronds, essentially similar to _fenestella_ in their structure, springing in a continuous spiral from a strong screw-like vertical axis. the outside of the fronds is simply striated; but the branches exhibit on the interior the mouths of the little cells in which the semi-independent beings composing the colony originally lived. [illustration: fig. .--carboniferous _braciopoda. a, _producta semireticulata_, showing the slightly concave dorsal valve; a' side view of the same, showing the convex ventral valve; b, _producta longispina_; c, _orthis resupinata_; d, _terebratula hastata_; e, _athyris subtilita_; f, _chonetes hardrensis_; g, _rhynchonella pleurodon_; h, _spirifera trigonalis_. most of these forms are widely distributed in the carboniferous limestone of britain, europe, america, &c. all the figures are of the natural size. (after davidson, de koninck, and meek.)] the _brachiopods_ are extremely abundant, and for the most part belong to types which are exclusively or principally palæozoic in their range. the old genera _strophomena, orthis_ (fig. , c), _athyris_ (fig. , e), _rhynchonella_ (fig. , g), and _spirifera_ (fig. , h), are still well represented--the latter, in particular, existing under numerous specific forms, conspicuous by their abundance and sometimes by their size. along with these ancient groups, we have representatives--for the first time in any plenty--of the great genus _terebratula_ (fig. , d), which underwent a great expansion during later periods, and still exists at the present day. the most characteristic carboniferous brachiopods, however, belong to the family of the _productidoe_, of which the principal genus is _producta_ itself. this family commenced its existence in the upper silurian with the genus _chonetes_, distinguished by its spinose hinge-margin. this genus lived through the devonian, and flourished in the carboniferous (fig. , f). the genus _producta_ itself, represented in the devonian by the nearly allied _productella_, appeared first in the carboniferous, at any rate, in force, and survived into the permian; but no member of this extensive family has yet been shown to have over-lived the palæozoic period. the _productoe_ of the carboniferous are not only exceedingly abundant, but they have in many instances a most extensive geographical range, and some species attain what may fairly be considered-gigantic dimensions. the shell (fig. , a and b) is generally more or less semicircular, with a straight hinge-margin, and having its lateral angles produced into larger or smaller ears (hence its generic name--"_cochlea producta_"). one valve (the ventral) is usually strongly convex, whilst the other (the dorsal) is flat or concave, the surface of both being adorned with radiating ribs, and with hollow tubular spines, often of great length. the valves are not locked together by teeth, and there is no sign in the fully-grown shell of an opening in or between the valves for the emission of a muscular stalk for the attachment of the shell to foreign objects. it is probable, therefore, that the _productoe_, unlike the ordinary lamp-shells, lived an independent existence, their long spines apparently serving to anchor them firmly in the mud or ooze of the sea-bottom; but mr robert etheridge, jun.; has recently shown that in one species the spines were actually employed as organs of adhesion, whereby the shell was permanently attached to some extraneous object, such as the stem of a crinoid. the two species here figured are interesting for their extraordinarily extensive geographical range--_producta semireticulata_ (fig. , a) being found in the carboniferous rocks of britain, the continent of europe, central asia, china, india, australia, spitzbergen, and north and south america; whilst _p. longispina_ (fig. , b) has a distribution little if at all less wide. [illustration: fig. .--_pupa (dendropupa) vetusta_, a carboniferous land-snail from the coal-measures of nova scotia. a, the shell, of the natural size; b, the same, magnified; c, apex of the shell, enlarged; d, portion of the surface, enlarged. (after dawson.)] the higher _mollusca_ are abundantly represented in the carboniferous rocks by bivalves (_lamellibranchs_), univalves (_gasteropoda_), winged-snails (_pteropoda_), and _cephalopods_. amongst the bivalves we may note the great abundance of scallops (_aviculopecten_ and other allied forms), together with numerous other types--some of ancient origin, others represented here for the first time. amongst the gasteropods, we find the characteristically palæozoic genera _macrocheilus_ and _loxonema_, the almost exclusively palæozoic _euomphalus_, and the persistent, genus _pleurotomaria_; whilst the free-swimming univalves (_heteropoda_)are represented by _bellerophon_ and _porcellia_, and the _pteropoda_ by the old genus _conularia_. with regard to the carboniferous univalves, it is also of interest to note here the first appearance of true air-breathing or terrestrial molluscs, as discovered by dawson and bradley in the coal-measures of nova scotia and illinois. some of these (_conulus priscus_) are true land-snails, resembling the existing _zonites_; whilst others (_pupa vetusta_, fig. ) appear to be generically inseparable from the "chrysalis-shells" (_pupa_) of the present day. all the known forms--three in number--are of small size, and appear to have been local in their distribution or in their preservation. more important, however, than any of the preceding, are the _cephalopoda_, represented, as before, exclusively by the chambered shells of the tetrabranchiates. the older and simpler type of these, with simple plain septa, and mostly a central siphuncle, is represented by the straight conical shells of the ancient genus orthoceras, and the bow-shaped shells of the equally ancient _cyrtoceras_--some of the former attaining a great size. the spirally-curved discoidal shells of the persistent genus _nautilus_ are also not unknown, and some of these likewise exhibit very considerable dimensions. lastly, the more complex family of the _ammonitidoe_, with lobed or angulated septa, and a dorsally-placed siphuncle (situated on the convex side of the curved shells), now for the first time commences to acquire a considerable prominence. the principal representative of this group is the genus _goniatites_ (fig. ), which commenced its existence in the upper silurian, is well represented in the devonian, and attains its maximum here. in this genus, the shell is spirally curved, the septa are strongly lobed or angulated, though not elaborately frilled as in the ammonites, and the siphuncle is dorsal. in addition to _goniatites_, the shells of true _ammonites_, so characteristic of the secondary period, have been described by dr waagen as occurring in the carboniferous rocks of india. [illustration: fig. .--_goniatites (aganides) fossoe_. carboniferous limestone.] [illustration: fig. .--_amblypterus macropterus_. carboniferous.] coming finally to the _vertebrata_, we have in the first place to very briefly consider the carboniferous _fishes_. these are numerous; but, with the exception of the still dubious "conodonts," belong wholly to the groups of the _ganoids_ and the _placoids_ (including under the former head remains which perhaps are truly referable to the group of the _dipnoi_ or mud-fishes). amongst the _ganoids_, the singular buckler-headed fishes of the upper silurian and devonian (_cephalaspidoe_) have apparently disappeared; and the principal types of the carboniferous belong to the groups respectively represented at the present day by the gar pike (_lepidosteus_) of the north american lakes, and the _polypterus_ of the rivers of africa. of the former, the genera _paloeoniscus_ and _amblypterus_ (fig. ), with their small rhomboidal and enamelled scales, and their strongly unsymmetrical tails, are perhaps the most abundant. of the latter, the most important are species belonging to the genera _megalichthys_ and _rhizodus_, comprising large fishes, with rhomboidal scales, unsymmetrical ("heterocercal") tails, and powerful conical teeth. these fishes are sometimes said to be "sauroid," from their presenting some reptilian features in their organisation, and they must have been the scourges of the carboniferous seas. the remains of _placoid_ fishes in the carboniferous strata are very numerous, but consist wholly of teeth and fin-spines, referable to forms more or less closely allied to our existing port jackson sharks, dog-fishes, and rays. the teeth are of very various shapes and sizes,--some with sharp, cutting edges (_petalodus, cladodus_, &c.); others in the form of broad crushing plates, adapted, like the teeth of the existing port jackson shark (_cestracion philippi_), for breaking down the hard shells of molluscs and crustaceans. amongst the many kinds of these latter, the teeth of _psammodus_ and _cochliodus_ (fig. ) may be mentioned as specially characteristic. the fin-spines are mostly similar to those so common in the devonian deposits, consisting of hollow defensive spines implanted in front of the pectoral or other fins, usually slightly curved, often superficially ribbed or sculptured, and not uncommonly serrated or toothed. the genera _ctenacanthus, gyracanthus, homacanthus_, &c., have been founded for the reception of these defensive weapons, some of which indicate fishes of great size and predaceous habits. [illustration: fig. .--teeth of _cochliodus contortus_. carboniferous limestone, britain.] [illustration: fig. .--a, upper surface of the skull of _anthracosaurus russelli_, one-sixth of the natural size: b, part of one of the teeth cut across, and highly magnified to show the characteristic labyrinthine structure; c, one of the integumentary shields or scales, one-half of the natural size. coal-measures, northumberland. (after atthey.)] in the devonian rocks we meet with no other remains of vertebrated animals save fishes only; but the carboniferous deposits have yielded remains of the higher group of the _amphibians_. this class, comprising our existing frogs, toads, and newts, stands to some extent in a position midway between the class of the fishes and that of the true reptiles, being distinguished from the latter by the fact that its members invariably possess gills in their early condition, if not throughout life; whilst they are separated from the former by always possessing true lungs when adult, and by the fact that the limbs (when present at all) are never in the form of fins. the amphibians, therefore, are all water-breathers when young, and have respiratory organs adapted for an aquatic mode of life; whereas, when grown up, they develop lungs, and with these the capacity for breathing air directly. some of them, like the frogs and newts, lose their gills altogether on attaining the adult condition; but others, such as the living _proteus_ and _menobranchus_, retain their gills even after acquiring their lungs, and are thus fitted indifferently for an aquatic or terrestrial existence. the name of "amphibia," though applied to the whole class, is thus not precisely appropriate except to these last-mentioned forms (gr. _amphi_, both; _bios_, life). the amphibians also differ amongst themselves according as to whether they keep permanently the long tail which they all possess when young (as do the newts and salamanders), or lose this appendage when grown up (as do the frogs and toads). most of them have naked skins, but a few living and many extinct forms have hard structures in the shape of scales developed in the integument. all of them have well-ossified skeletons, though some fossil types are partially deficient in this respect; and all of them which possess limbs at all have these appendages supported by bones essentially similar to those found in the limbs of the higher vertebrates. all the carboniferous amphibians belong to a group which has now wholly passed away--namely, that of the _labyrinthodonts_. in the marine strata which form the base of the carboniferous series these creatures have only been recognised by their curious hand-shaped footprints, similar in character to those which occur in the triassic rocks, and which will be subsequently spoken of under the name of _cheirotherium_. in the coal-measures of britain, the continent of europe, and north america, however, many bones of these animals have been found, and we are now tolerably well acquainted with a considerable number of forms. all of them seem to have belonged to the division of amphibians in which the long tail of the young is permanently retained; and there is evidence that some of them kept the gills also throughout life. the skull is of the characteristic amphibian type (fig. , a), with two occipital condyles, and having its surface singularly pitted and sculptured; and the vertebræ are hollowed out at both ends. the lower surface of the body was defended by an armour of singular integumentary shields or scales (fig. , c); and an extremely characteristic feature (from which the entire group derives its name) is, that the walls of the teeth are deeply folded, so as to give rise to an extraordinary "labyrinthine" pattern when they are cut across (fig. , b). many of the carboniferous labyrinthodonts are of no great size, some of them very small, but others attain comparatively gigantic dimensions, though all fall short in this respect of the huge examples of this group which occur in the trias. one of the largest, and at the same time most characteristic, forms of the carboniferous series, is the genus _anthracosaurus_, the skull of which is here figured. no remains of true reptiles, birds, or quadrupeds have as yet been certainly detected in the carboniferous deposits in any part of the world. it should, however, be mentioned, that professor marsh, one of the highest authorities on the subject, has described from the coal-formation of nova scotia certain vertebræ which he believes to have belonged to a marine reptile (_eosaurus acadianus_), allied to the great _ichthyosauri_ of the lias. up to this time no confirmation of this determination has been obtained by the discovery of other and more unquestionable remains, and it therefore remains doubtful whether these bones of _eosaurus_ may not really belong to large labyrinthodonts. literature. the following list contains some of the more important of the original sources of information to which the student of carboniferous rocks and fossils may refer:-- ( ) 'geology of yorkshire,' vol. ii.; 'the mountain limestone district.' john phillips. ( ) 'siluria.' sir roderick murchison. ( ) 'memoirs of the geological survey of great britain and ireland.' ( ) 'geological report on londonderry,' &c. portlock. ( ) 'acadian geology.' dawson. ( ) 'geology of iowa,' vol. i. james hall. ( ) 'reports of the geological survey of illinois' (geology and palæontology). meek, worthen, &c. ( ) 'reports of the geological survey of ohio' (geology and palæontology). newberry, cope, meek, hall, &c. ( ) 'description des animaux fossiles qui se trouvent dans le terrain carbonifère de la belgique,' ; with subsequent monographs on the genera _productus_ and _chonetes_, on _crinoids_, on _corals_, &c. de koninck. ( ) 'synopsis of the carboniferous fossils of ireland.' m'coy. ( ) 'british palæozoic fossils.' m'coy. ( ) 'figures of characteristic british fossils.' baily. ( ) 'catalogue of british fossils.' morris. ( ) 'monograph of the carboniferous brachiopoda of britain' (palæontographical society). davidson. ( ) 'monograph of the british carboniferous corals' (palæontographical society). milne-edwards and haime. ( ) 'monograph of the carboniferous bivalve entomostraca of britain' (palæontographical society). rupert jones, kirkby, and george s. brady. ( ) 'monograph of the carboniferous foraminifera of britain' (palæontographical society). h. b. brady. ( ) "on the carboniferous fossils of the west of scotland"--'trans. geol. soc.,' of glasgow, vol. iii., supplement. young and armstrong. ( ) 'poissons fossiles.' agassiz. ( ) "report on the labyrinthodonts of the coal-measures"--'british association report,' . l. c. miall. ( ) 'introduction to the study of palæontological botany.' john hutton balfour. ( ) 'traité de paléontologie végétale.' schimper. ( ) 'fossil flora.' lindley and hutton. ( ) 'histoire des végétaux fossiles.' brongniart. ( ) 'on calamites and calamodendron' (monographs of the palæontographical society). binney. ( ) 'on the structure of fossil plants found in the carboniferous strata' (palæontographical society). binney. also numerous memoirs by huxley, davidson, martin duncan, professor young, john young, r. etheridge, jun., baily, carruthers, dawson, binney, williamson, hooker, jukes, geikie, rupert jones, salter, and many other british and foreign observers. chapter xiv. the permian period. the permian formation closes the long series of the palæozoic deposits, and may in some respects be considered as a kind of appendix to the carboniferous system, to which it cannot be compared in importance, either as regards the actual bulk of its sediments or the interest and variety of its life-record. consisting, as it does, largely of red rocks--sandstones and marls--for the most part singularly destitute of organic remains, the permian rocks have been regarded as a lacustrine or fluviatile deposit; but the presence of well-developed limestones with indubitable marine remains entirely negatives this view. it is, however, not improbable that we are presented in the permian formation, as known to us at present, with a series of sediments laid down in inland seas of great extent, due to the subsidence over large areas of the vast land-surfaces of the coal-measures. this view, at any rate, would explain some of the more puzzling physical characters of the formation, and would not be definitely negatived by any of its fossils. a large portion of the permian series, as already remarked, consists of sandstones and marls, deeply reddened by peroxide of iron, and often accompanied by beds of gypsum or deposits of salt. in strata of this nature few or no fossils are found; but their shallow-water origin is sufficiently proved by the presence of the footprints of terrestrial animals, accompanied in some cases by well-defined "ripple-marks." along with these are occasionally found massive breccias, holding larger or smaller blocks derived from the older formations; and these have been supposed to represent an old "boulder-clay," and thus to indicate the prevalence of an arctic climate. beds of this nature must also have been deposited in shallow water. in all regions, however, where the permian formation is well developed, one of its most characteristic members is a magnesian limestone, often highly and fantastically concretionary, but containing numerous remains of genuine marine animals, and clearly indicating that it was deposited beneath a moderate depth of salt water. it is not necessary to consider here whether this formation can be retained as a distinct division of the geological series. the name of _permian_ was given to it by sir roderick murchison, from the province of perm in russia, where rocks of this age are extensively developed. formerly these rocks were grouped with the succeeding formation of the trias under the common name of "new red sandstone." this name was given them because they contain a good deal of red sandstone, and because they are superior to the carboniferous rocks, while the old red sandstone is inferior. nowadays, however, the term "new red sandstone" is rarely employed, unless it be for red sandstones and associated rocks, which are seen to overlie the coal-measures, but which contain no fossils by which their exact age may be made out. under these circumstances, it is sometimes convenient to employ the term "new red sandstone." the new red, however, of the older geologists, is now broken up into the two formations of the permian and triassic rocks--the former being usually considered as the top of the palæozoic series, and the latter constituting the base of the mesozoic. in many instances, the permian rocks are seen to repose unconformably upon the underlying carboniferous, from which they can in addition be readily separated by their lithological characters. in other instances, however, the coal-measures terminate upwards in red rocks, not distinguishable by their mineral characters from the permian; and in other cases no physical discordance between the carboniferous and permian strata can be detected. as a general rule, also, the permian rocks appear to pass upwards conformably into the trias. the division, therefore, between the permian and triassic rocks, and consequently between the palæozoic and mesozoic series, is not founded upon any conspicuous or universal physical break, but upon the difference in life which is observed in comparing the marine animals of the carboniferous and permian with those of the trias. it is to be observed, however, that this difference can be solely due to the fact that the magnesian limestone of the permian series presents us with only a small, and not a typical, portion of the marine deposits which must have been accumulated in some area at present unknown to us during the period which elapsed between the formation of the great marine limestones of the lower carboniferous and the open-sea and likewise calcareous sediments of the middle trias. the permian rocks exhibit their most typical features in russia and germany, though they are very well developed in parts of britain, and they occur in north america. when well developed, they exhibit three main divisions: a lower set of sandstones, a middle group, generally calcareous, and an upper series of sandstones, constituting respectively the lower, middle, and upper permians. in russia, germany, and britain, the permian rocks consist of the following members:-- . the _lower permians_, consisting mainly of a great series of sandstones, of different colours, but usually red. the base of this series is often constituted by massive breccias with included fragments of the older rocks, upon which they may happen to repose; and similar breccias sometimes occur in the upper portion of the series as well. the thickness of this group varies a good deal, but may amount to or feet. . the _middle permians_, consisting, in their typical development, of laminated marls, or "marl-slate," surmounted by beds of magnesian limestone (the "zechstein" of the german geologists). sometimes the limestones are degenerate or wholly deficient, and the series may consist of sandy shales and gypsiferous clays. the magnesian limestone, however, of the middle permians is, as a rule, so well marked a feature that it was long spoken of as _the_ magnesian limestone. . the _upper permians_, consisting of a series of sandstones and shales, or of red or mottled marls, often gypsiferous, and sometimes including beds of limestone. in north america, the permian rocks appear to be confined to the region west of the mississippi, being especially well developed in kansas. their exact limits have not as yet been made out, and their total thickness is not more than a few hundred feet. they consist of sandstones, conglomerates, limestones, marls, and beds of gypsum. the following diagrammatic section shows the general sequence of the permian deposits in the north of england, where the series is extensively developed (fig. ):-- [illustration: fig. . generalised section of the permian rocks in the north of england.] the record of the _life_ of the permian period is but a scanty one, owing doubtless to the special peculiarities of such of the deposits of this age with which we are as yet acquainted. red rocks are, as a general rule, more or less completely unfossiliferous, and sediments of this nature are highly characteristic of the permian. similarly, magnesian limestones are rarely as highly charged with organic remains as is the case with normal calcareous deposits, especially when they have been subjected to concretionary action, as is observable to such a marked extent in the permian limestones. nevertheless, much interest is attached to the organic remains, as marking a kind of transition-period between the palæozoic and mesozoic epochs. [illustration: fig. .--_walchia piniformis_, from the permian of saxony, a, branch; b, twig, (after gutbier.)] the _plants_ of the permian period, as a whole, have a distinctly palæozoic aspect, and are far more nearly allied to those of the coal-measures than they are to those of the earlier secondary rocks; though the permian _species_ are mostly distinct from the carboniferous, and there are some new genera. thus, we find species of _lepidodendron, calamites, equisetites, asterophyllites, annularia_, and other highly characteristic carboniferous genera. on the other hand, the _sigillariods_ of the coal seem to have finally disappeared at the close of the carboniferous period. ferns are abundant in the permian rocks, and belong for the most part to the well-known carboniferous genera _alethopteris, neuropteris, sphenopteris_, and _pecopteris_. there are also tree-ferns referable to the ancient genus _psaronius_. the _conifers_ of the permian period are numerous, and belong in part to carboniferous genera. a characteristic genus, however, is _walchia_ (fig. ), distinguished by its lax short leaves. this genus, though not exclusively permian, is mainly so, the best-known species being the _w. piniformis_. here, also, we meet with conifers which produce true cones, and which differ, therefore, in an important degree from the taxoid conifers of the coal-measures. besides _walchia_, a characteristic form of these is the _ullmania selaginoides_, which occurs in the magnesian limestone of durham, the middle permian of westmorland, and the "kupfer-schiefer" of germany. the group of the _cycads_, which we shall subsequently find to be so characteristic of the vegetation of the secondary period, is, on the other hand, only doubtfully represented in the permian deposits by the singular genus _noeggerathia_. the _protozoans_ of the permian rocks are few in number, and for the most part imperfectly known. a few _foraminifera_ have been obtained from the magnesian limestone of england, and the same formation has yielded some ill-understood sponges. it does not seem, however, altogether impossible that some of the singular "concretions" of this formation may ultimately prove to have an organic structure, though others would appear to be clearly of purely inorganic origin. from the permian of saxony, professor geinitz has described two species of _spongillopsis_, which he believes to be most nearly allied to the existing fresh-water sponges (_spongilla_). this observation has an interest as bearing upon the mode of deposition and origin of the permian sediments. the _coelenterates_ are represented in the permian by but a few corals. these belong partly to the _tabulate_ and partly to the _rugose_ division; but the latter great group, so abundantly represented in silurian, devonian, and carboniferous seas, is now extraordinarily reduced in numbers, the british strata of this age yielding only species of the single genus _polycoelia_. so far, therefore, as at present known, all the characteristic genera of the rugose corals of the carboniferous had become extinct before the deposition of the limestones of the middle permian. the _echinoderms_ are represented by a few _crinoids_, and by a sea-urchin belonging to the genus _eocidaris_. the latter genus is nearly allied to the _archoeocidaris_ of the carboniferous, so that this permian form belongs to a characteristically palæozoic type. a few _annelides_ (_spirorbis, vermilia_, &c.) have been described, but are of no special importance. amongst the _crustaceans_, however, we have to note the total absence of the great palæozoic group of the _trilobites_; whilst the little _ostracoda_ and _phyllopods_ still continue to be represented. we have also to note the first appearance here of the "short-tailed" decapods or crabs (_brachyura_), the highest of all the groups of _crustacea_, in the person of _hemitrochiscus paradoxus_, an extremely minute crab from the permian of germany. [illustration: fig. .--brachiopods of the permian formation. a, _producta horrida_; b, _lingula credneri_; c, _terebratula elongata_; d and e, _camarophoria globulina_. (after king.)] amongst the _mollusca_, the remains of _polyzoa_ may fairly be said to be amongst the most abundant of all the fossils of the permian formation, the principal forms of these are the fronds of the lace-corals (_fenestella, retepora_, and _synocladia_), which are very abundant in the magnesian limestone of the north of england, and belong to various highly characteristic species (such as _fenestella retiformis, retepora ehrenbergi_, and _synocladia virgulacea_). the _brachiopoda_ are also represented in moderate numbers in the permian. along with species of the persistent genera _discina, crania_, and _lingula_, we still meet with representatives of the old groups _spirifera, athyris_, and _streptorhynchus_; and the carboniferous _productoe_ yet survive under well-marked and characteristic types, though in much-diminished numbers. the species of brachiopods here figured (fig. ) are characteristic of the magnesian limestone in britain and of the corresponding strata on the continent. upon the whole, the most characteristic permian _brachiopods_ belong to the genera _producta, strophalosia_, and _camarophoria_. the _bivalves_ (_lamellibranchiata_) have a tolerably varied development in the permian rocks; but nearly all the old types, except some of those which occur in the carboniferous, have now disappeared. the principal permian bivalves belong to the groups of the pearl oysters (_aviculidoe_) and the _trigoniadoe_, represented by genera such as _bakewellia_ and _schizodus_; the true mussels (_mytilidoe_), represented by species which have been referred to _mytilus_ itself; and the arks (_arcadoe_), represented by species of the genera _arca_ (fig. ) and _byssoarca_. the first and last of these three families have a very ancient origin; but the family of the _trigoniadoe_, though feebly represented at the present day, is one which attained its maximum development in the mesozoic period. [illustration: fig. .--_arca antiqua_. permian.] the _univalves_ (_gasteropoda_) are rare, and do not demand special notice. it may be observed, however, that the palæozoic genera _euomphalus, murchisonia, loxonema_, and _macrocheilus_ are still in existence, together with the persistent genus _pleurotomaria_. _pteropods_ of the old genera _theca_ and _conularia_ have been discovered; but the first of these characteristically palæozoic types finally dies out here, and the second only survives but a short time longer. lastly, a few _cephalopods_ have been found, still wholly referable to the tetrabranchiate group, and belonging to the old genera _orthoceras_ and _cyrtoceras_ and the long-lived _nautilus_. [illustration: fig. .--_platysomus gibbosus_, a "heterocercal" ganoid, from the middle permian of russia.] amongst _vertebrates_, we meet in the permian period not only with the remains of fishes and amphibians, but also, for the first time, with true reptiles. the _fishes_ are mainly _ganoids_, though there are also remains of a few cestraciont sharks. not only are the _ganoids_ still the predominant group of fishes, but all the known forms possess the unsymmetrical ("heterocercal") tail which is so characteristic of the palæozoic ganoids. most of the remains of the permian fishes have been obtained from the "marl-slate" of durham and the corresponding "kupfer-schiefer" of germany, on the horizon of the middle permian; and the principal genera of the ganoids are _paloeoniscus_ and _platysomus_ (fig. ). the _amphibians_ of the permian period belong principally to the order of the _labyrinthodonts_, which commenced to be represented in the carboniferous, and has a large development in the trias. under the name, however, of _paloeosiren beinerti_, professor geinitz has described an amphibian from the lower permian of germany, which he believes to be most nearly allied to the existing "mud-eel" (_siren lacertina_) of north america, and therefore to be related to the newts and salamanders (_urodela_). [illustration: fig. .--_protorosaurus speneri_, middle permian, thuringia, reduced in size. (after von meyer.) [copied from dana.]] finally, we meet in the permian deposits with the first undoubted remains of true _reptiles_. these are distinguished, as a class, from the _amphibians_, by the fact that they are air-breathers throughout the whole of their life, and therefore are at no time provided with gills; whilst they are exempt from that metamorphosis which all the _amphibia_ undergo in early life, consequent upon their transition from an aquatic to a more or less purely aerial mode of respiration. their skeleton is well ossified; they usually have horny or bony plates, singly or in combination, developed in the skin; and their limbs (when present) are never either in the form of _fins_ or _wings_, though sometimes capable of acting in either of these capacities, and liable to great modifications of form and structure. though there can be no doubt whatever as to the occurrence of genuine reptiles in deposits of unquestionable permian age, there is still uncertainty as to the precise number of types which may have existed at this period. this uncertainty arises partly from the difficulty of deciding in all cases, whether a given bone be truely labyrinthodont or reptilian, but more especially from the confusion which exists at present between the permian and the overlying triassic deposits. thus there are various deposits in different regions which have yielded the remains of reptiles, and which cannot in the meanwhile be definitely referred either to the permian series or to the trias by clear stratigraphical or palæontological evidence. all that can be done in such cases is to be guided by the characters of the reptiles themselves, and to judge by their affinities to remains from known triassic or permian rocks to which of these formations the beds containing them should be referred; but it is obvious that this method of procedure is seriously liable to lead to error. in accordance, however, with this, the only available mode of determination in some cases, the remains of _thecodontosaurus_ and _palæosaurus_ discovered in the dolomitic conglomerates near bristol will be considered as triassic, thus leaving _protorosaurus_[ ] as the principal and most important representative of the permian reptiles.[ ] the type-species of the genus _protorusaurus_ is the _p. speneri_(fig. ) of the "kupfer-schiefer" of thuringia, but other allied species have been detected in the middle permian of germany and the north of england. this reptile attained a length of from three to four feet; and it has been generally referred to the group of the lizards (_lacertilia_), to which it is most nearly allied in its general structure, at the same time that it differs from all existing members of this group in the fact that its numerous conical and pointed teeth were implanted in distinct sockets in the jaws--this being a crocodilian character. in other respects, however, _protorosaurus_ approximates closely to the living monitors (_varanidoe_); and the fact that the bodies of the vertebræ are slightly cupped or hollowed out at the ends would lead to the belief that the animal was aquatic in its habits. at the same time, the structure of the hind-limbs and their bony supports proves clearly that it must have also possessed the power of progression upon the land. various other reptilian bones have been described from the permian formation, of which some are probably really referable to labyrinthodonts, whilst others are regarded by professor owen as referable to the order of the "theriodonts," in which the teeth are implanted in sockets, and resemble those of carnivorous quadrupeds in consisting of three groups in each jaw (namely, incisors, canines, and molars). lastly, in red sandstones of permian age in dumfriesshire have been discovered the tracks of what would appear to have been _chelonians_ (tortoises and turtles); but it would not be safe to accept this conclusion as certain upon the evidence of footprints alone. the _chelichnus duncani_, however, described by sir william jardine in his magnificent work on the 'ichnology of annandale,' bears a great resemblance to the track of a turtle. [footnote : though commonly spelt as above, it is probable that the name of this lizard was really intended to have been _proterosaurus_--from the greek _proteros_, first; and _saura_, lizard: and this spelling is followed by many writers.] [footnote : in an extremely able paper upon the subject (quart. journ. geol. soc., vol. xxvi.), mr etheridge has shown that there are good physical grounds for regarding the dolomitie conglomerate of bristol as of triassic age, and as probably corresponding in time with the muschelkalk of the continent.] no remains of birds or quadrupeds have hitherto been detected in deposits of permian age. literature. the following works may be consulted by the student with regard to the permian formation and its fossils:-- ( ) "on the geological relations and internal structure of the magnesian limestone and the lower portions of the new red sandstone series, &c."--'trans. geol. soc.,' ser. , vol. iii. sedgwick. ( ) 'the geology of russia in europe.' murchison, de verneuil, and von keyserling. ( ) 'siluria,' murchison. ( ) 'permische system in sachsen.' geinitz and gutbier. ( ) 'die versteinerungen des deutschen zechsteingebirges,' geinitz. ( ) 'die animalischen ueberreste der dyas.' geinitz. ( ) 'monograph of the permian fossils of england' (palæontographical society). king. ( ) 'monograph of the permian brachiopoda of britain' (palæontographical society). davidson. ( ) "on the permian rocks of the north-west of england and their extension into scotland"--'quart. journ. geol. soc.,' vol. xx. murchison and harkness. ( ) 'catalogue of the fossils of the permian system of the counties of northumberland and durham.' howse. ( ) 'petrefacta germaniæ.' goldfuss. ( ) 'beiträge zur petrefaktenkunde.' munster. ( ) 'ein beitrag zur palæontologie des deutschen zechsteingebirges.' von schauroth. ( ) 'saurier aus dem kupfer-schiefer der zechstein-formation.' von meyer. ( ) 'manual of palæontology.' owen. ( ) 'recherches sur les poissons fossiles.' agassiz. ( ) 'ichnology of annandale.' sir william jardine. ( ) 'die fossile flora der permischen formation.' goeppert. ( ) 'genera et species plantarum fossilium.' unger. ( ) "on the red rocks of england of older date than the trias" --'quart. journ. geol. soc.,' vol. xxvii. ramsay. chapter xv. the triassic period. we come now to the consideration of the great _mesozoic_, or secondary series of formations, consisting, in ascending order, of the triassic, jurassic, and cretaceous systems. the triassic group forms the base of the mesozoic series, and corresponds with the higher portion of the new red sandstone of the older geologists. like the permian rocks, and as implied by its name, the _trias_ admits of a subdivision into three groups--a lower, middle, and upper trias. of these sub-divisions the middle one is wanting in britain; and all have received german names, being more largely and typically developed in germany than in any other country. thus, the lower trias is known as the _bunter sandstein_; the middle trias is called the _muschelkalk_; and the upper trias is known as the _keuper_. i. the lowest division of the trias is known as the _bunter sandstein_ (the _grès bigarré_ of the french), from the generally variegated colours of the beds which compose it (german, _bunt_, variegated). the bunter sandstein of the continent of europe consists of red and white sandstones, with red clays, and thin limestones, the whole attaining a thickness of about feet. the term "marl" is very generally employed to designate the clays of the lower and upper trias; but the term is inappropriate, as they may contain no lime, and are therefore not always genuine marls. in britain the bunter sandstein consists of red and mottled sandstones, with unconsolidated conglomerates, or "pebble-beds," the whole having a thickness of to feet. the bunter sandstein, as a rule, is very barren of fossils. ii. the middle trias is not developed in britain, but it is largely developed in germany, where it constitutes what is known as the _muschelkalk_ (germ. _muschel_, mussel; _kalk_, limestone), from the abundance of fossil shells which it contains. the muschelkalk (the _calcaire coquillier_ of the french) consists of compact grey or yellowish limestones, sometimes dolomitic, and including occasional beds of gypsum and rock-salt. iii. the upper trias, or _keuper_ (the _marnes irisées_ of the french), as it is generally called, occurs in england; but is not so well developed as it is in germany. in britain, the keuper is feet or more in thickness, and consists of white and brown sandstones, with red marls, the whole topped by red clays with rock-salt and gypsum. the keuper in britain is extremely unfossiliferous; but it passes upwards with perfect conformity into a very remarkable group of beds, at one time classed with the lias, and now known under the names of the penarth beds (from penarth, in glamorganshire), the rhætic beds (from the rhætic alps), or the _avicula contorta_ beds (from the occurrence in them of great numbers of this peculiar bivalve). these singular beds have been variously regarded as the highest beds of the trias, or the lowest beds of the lias, or as an intermediate group. the phenomena observed on the continent, however, render it best to consider them as triassic, as they certainly agree with the so-called upper st cassian or kössen beds which form the top of the trias in the austrian alps. the penarth beds occur in glamorganshire, gloucestershire, warwickshire, staffordshire, and the north of ireland; and they generally consist of a small thickness of grey marls, white limestones, and black shales, surmounted conformably by the lowest beds of the lias. the most characteristic fossils which they contain are the three bivalves _cardium rhoeticum, avicula contorta_, and _pecten valoniensis_; but they have yielded many other fossils, amongst which the most important are the remains of fishes and small mammals (_microlestes_). in the austrian alps the trias terminates upwards in an extraordinary series of fossiliferous beds, replete with marine fossils. sir charles lyell gives the following table of these remarkable deposits:-- _strata below the lias in the austrian alps, in descending order._ / grey and black limestone, with calcareous | marls having a thickness of about | feet. among the fossils, brachiopoda . koessen beds. | very numerous; some few species common (synonyms, upper | to the genuine lias; many peculiar. st cassian beds of < _avicula contorta, pecten valoniensis_, escher and merian.) | _cardium rhoeticum, avicula_ | _inoequivalvis, spirifer münsteri_, | dav. strata containing the above fossils | alternate with the dachstein beds, lying \ next below. / white or greyish limestone, often in beds | three or four feet thick. total thickness | of the formation above feet. upper | part fossiliferous, with some strata . dachstein beds. < composed of corals (_lithodendron_.) | lower portion without fossils. among the | characteristic shells are _hemicardium_ | _wulfeni, megalodon triqueler_, and \ other large bivalves. / red, pink, or white marbles, from to | feet in thickness, containing more | than species of marine fossils, for . hallstadt beds | the most part mollusca. many species of (or st cassian). < _orthoceras_. true _ammonites_, | besides _ceratites_ and | _goniatites, belemnites_ (rare), | _porcellia, pleurotomania, trochus_, \ _monotis salinaria_, &c. / a. black and grey \ among the fossils . a. guttenstein beds. | limestone feet | are _ceratites_ b. werfen beds, base | thick, alternating | _cassianus_, of upper trias? | with the underlying | _myacites_ lower trias of < werfen beds. > _fassaensis_, some geologists. | b. red and green | _naticella_ | shale and sandstone, | _costata_, &c. \ with salt and gypsum./ in the united states, rocks of triassic age occur in several areas between the appalachians and the atlantic seaboard; but they show no such triple division as in germany, and their exact place in the system is uncertain. the rocks of these areas consist of red sandstones, sometimes shaly or conglomeratic, occasionally with beds of impure limestone. other more extensive areas where triassic rocks appear at the surface, are found west of the mississippi, on the slopes of the rocky mountains, where the beds consist of sandstones and gypsiferous marls. the american trias is chiefly remarkable for having yielded the remains of a small marsupial (_dromatherium_), and numerous footprints, which have generally been referred to birds (_brontozoum_), along with the tracks of undoubted reptiles (_otozoum, anisopus_, &c.) the subjoined section (fig. ) expresses, in a diagrammatic manner, the general sequence of the triassic rocks when fully developed, as, for example, in the bavarian alps:-- [illustration: fig. . generalized section of the triassic rocks of central europe.] with regard to the _life_ of the triassic period, we have to notice a difference as concerns the different members of the group similar to that which has been already mentioned in connection with the permian formation. the arenaceous deposits of the series, namely, resemble those of the permian, not only in being commonly red or variegated in their colour, but also in their conspicuous paucity of organic remains. they for the most part are either wholly unfossiliferous, or they contain the remains of plants or the bones of reptiles, such as may easily have been drifted from some neighbouring shore. the few fossils which may be considered as properly belonging to these deposits are chiefly crustaceans (_estheria_) or fishes, which may well have lived in the waters of estuaries or vast inland seas. we may therefore conclude, with considerable probability, that the barren sandy and marly accumulations of the bunter sandstein and lower keuper were not laid down in an open sea, but are probably brackish-water deposits, formed in estuaries or land-locked bodies of salt water. this at any rate would appear to be the case as regards these members of the series as developed in britain and in their typical areas on the continent of europe; and the origin of most of the north american trias would appear to be much the same. whether this view be correct or not, it is certain that the beds in question were laid down in _shallow_ water, and in the immediate vicinity of _land_, as shown by the numerous drifted plants which they contain and the common occurrence in them of the footprints of air-breathing animals (birds, reptiles, and amphibians). on the other hand, the middle and highest members of the trias are largely calcareous, and are replete with the remains of undoubted marine animals. there cannot, therefore, be the smallest doubt but that the muschelkalk and the rhætic or kössen beds were slowly accumulated in an open sea, of at least a moderate depth; and they have preserved for us a very considerable selection from the marine fauna of the triassic period. [illustration: fig. .--_zamia spiralis_, a living cycad. australia.] the _plants_ of the trias are, on the whole, as distinctively mesozoic in their aspect as those of the permian are palæozoic. in spite, therefore, of the great difficulty which is experienced in effecting a satisfactory stratigraphical separation between the permian and the trias, we have in this fact a proof that the two formations were divided by an interval of time sufficient to allow of enormous changes in the terrestrial vegetation of the world. the _lepidodendroids, asterophyllites_, and _annularioe_, of the coal and permian formations, have now apparently wholly disappeared: and the triassic flora consists mainly of ferns, cycads, and conifers, of which only the two last need special notice. the _cycads_ (fig. ) are true exogenous plants, which in general form and habit of growth present considerable resemblance to young palms, but which in reality are most nearly related to the pines and firs (_coniferoe_). the trunk is unbranched, often much shortened, and bears a crown of feathery pinnate fronds. the leaves are usually "circinate"--they unroll in expanding, like the fronds of ferns. the seeds are not protected by a seed-vessel, but are borne upon the edge of altered leaves, or are carried on the scales of a cone. all the living species of cycads are natives of warm countries, such as south america, the west indies, japan, australia, southern asia, and south africa. the remains of cycads, as we have seen, are not known to occur in the coal formation, or only to a very limited extent towards its close; nor are they known with certainty as occurring in permian deposits. in the triassic period, however, the remains of cycads belonging to such genera as _pterophyllum_ (fig. , b), _zamites_, and _podozamites_ (fig. , c), are sufficiently abundant to constitute quite a marked feature in the vegetation; and they continue to be abundantly represented throughout the whole mesozoic series. the name "age of cycads," as applied to the secondary epoch, is therefore, from a botanical point of view, an extremely appropriate one. the _conifers_ of the trias are not uncommon, the principal form being _veltzia_ (fig. , a), which possesses some peculiar characters, but would appear to be most nearly related to the recent cypresses. [illustration: fig. .--triassic conifers and cycads. a, _voltzia_ (_schizoneura_) _heterophylla_, portion of a branch, europe and america; b, part of the frond of _pterophyllum joegeri_, europe; c, part of the frond of _podozamites lanceolatus_, america.] as regards the _invertebrate animals_ of the trias, our knowledge is still principally derived from the calcareous beds which constitute the centre of the system (the muschelkalk) on the continent of europe, and from the st cassain and rhætic beds still higher in the series; whilst some of the triassic strata of california and nevada have likewise yielded numerous remains of marine invertebrates. the _protozoans_ are represented by _foraminifera_ and _sponges_, and the _coelenterates_ by a small number of _corals_; but these require no special notice. it may be mentioned, however, that the great palæozoic group of the _rugose_ corals has no known representative here, its place being taken by corals of secondary type (such as _montlivaltia, synastoea_, &c.) the _echinoderms_ are represented principally by _crinoids_, the remains of which are extremely abundant in some of the limestones. the best-known species is the famous "lily-encrinite" (_encrinus liliiformis_, fig. ), which is characteristic of the muschelkalk. in this beautiful species, the flower-like head is supported upon a rounded stem, the joints of which are elaborately articulated with one another; and the fringed arms are composed each of a double series of alternating calcareous pieces. the palæozoic urchins, with their supernumerary rows of plates, the cystideans, and the pentremites have finally disappeared; but both star-fishes and brittle-stars continue to be represented. one of the latter--namely, the _aspidura loricata_ of goldfuss (fig. )--is highly characteristic of the muschelkalk. [illustration: fig. .--head and upper part of the column of _encrinus liliiformis_. the lower figure shows the articulating surface of one of the joints of the column. muschelkalk, germany.] [illustration: fig. .--_aspidura loricata_, a triassic ophiuroid. muschelkalk, germany.] the remains of _articulate animals_ are not very abundant in the trias, if we except the bivalved cases of the little water-fleas (_ostracoda_), which are occasionally very plentiful. there are also many species of the horny, concentrically-striated valves of the _estherioe_ (see fig. , b), which might easily be taken for small bivalve molluscs. the "long-tailed" decapods of the type of the lobster, are not without examples but they become much more numerous in the succeeding jurassic period. remains of insects have also been discovered. amongst the _mollusca_ we have to note the disappearance, amongst the lower groups, of many characteristic palæozoic types. amongst the _polyzoans_, the characteristic "lace-corals," _fenestella, retepora_,[ ] _synocladia, polypora_, &c., have become apparently extinct. the same is true of many of the ancient types of _brachiopods_, and conspicuously so of the great family of the _productidoe_, which played such an important part in the seas of the carboniferous and permian periods. [footnote : the genus _retefora_ is really a recent one, represented by living forms; and the so-called _reteporoe_ of the palæozoic rocks should properly receive another name (_phyllopora_), as being of a different nature. the name _retepora_ has been here retained for these old forms simply in accordance with general usage.] [illustraton: fig. . triassic lamellibranchs. a, _daonella_ (_halobia_) _lommelli_; b, _pecten valoniensis_; c, _myophoria lineata_; d. _cardium rhoeticum_; e. _avicula contorta_; f. _avicula socialis_.] _bivalves_ (_lamellibranchiata_) and _univalves_ (_gasteropoda_) are well represented in the marine beds of the trias, and some of the former are particularly characteristic either of the formation as a whole or of minor subdivisions of it. a few of these characteristic species are figured in the accompanying illustration (fig. ). bivalve shells of the genera _daonella_ (fig. , a) and _halobia_ (_monotis_) are very abundant, and are found in the triassic strata of almost all regions. these groups belong to the family of the pearl-oysters (_aviculidoe_), and are singular from the striking resemblance borne by some of their included forms to the _strophomenoe amongst the lamp-shells, though, of course, no real relation exists between the two. the little pearl-oyster, _avicula socialis_ (fig. , f), is found throughout the greater part of the triassic series, and is especially abundant in the muschelkalk. the genus _myophoria_ (fig. , c), belonging to the _trigoniadoe_, and related therefore to the permian _schizodus_, is characteristically triassic, many species of the genus being known in deposits of this age. lastly, the so-called "rhætic" or "kössen" beds are characterised by the occurrence in them of the scallop, _pecten valoniensis_ (fig. , b); the small cockle, _cardium rhoeticum_ (fig. , d); and the curiously-twisted pearl-oyster, _avicula contorta_ (fig. , e)--this last bivalve being so abundant that the strata in question are often spoken of as the "avicula contorta beds." [illustration: fig. .--_ceratites nodosus_, viewed from the side and from behind. muschelkalk.] passing over the groups of the _heteropods_ and _pteropods_, we have to notice the _cephalopoda_, which are represented in the trias not only by the chambered shells of _tetrabranchiates_, but also, for the first time, by the internal skeletons of _dibranchiate_ forms. the trias, therefore, marks the first recognised appearance of true cuttle-fishes. all the known examples of these belong to the great mesozoic group of the _belemnitidoe_; and as this family is much more largely developed in the succeeding jurassic period, the consideration of its characters will be deferred till that formation is treated of. amongst the chambered _cephalopods_ we find quite a number of the palæozoic _orthoceratites_, some of them of considerable size, along with the ancient _cyrtoceras_ and _goniatites_; and these old types, singularly enough, occur in the higher portion of the trias (st cassian beds), but have, for some unexplained reason, not yet been recognised in the lower and equally fossiliferous formation of the muschelkalk. along with these we meet for the first time with true _ammonites_, which fill such an extensive place in the jurassic seas, and which will be spoken of hereafter. the form, however, which is most characteristic of the trias is _ceratites_ (fig. ). in this genus the shell is curved into a flat spiral, the volutions of which are in contact; and it further agrees with both _goniatites_ and _ammonites_ in the fact that the septa or partitions between the air-chambers are not simple and plain (as in the _nautilus_ and its allies), but are folded and bent as they approach the outer wall of the shell. in the _goniatite_ these foldings of the septa are of a simply lobed or angulated nature, and in the _ammonite_ they are extremely complex; whilst in the _ceratite_ there is an intermediate state of things, the special feature of which is, that those foldings which are turned towards the mouth of the shell are merely rounded, whereas those which are turned away from the mouth are characteristically toothed. the genus _ceratites_, though principally triassic, has recently been recognised in strata of carboniferous age in india. from the foregoing it will be gathered that one of the most important points in connection with the triassic _mollusca_ is the remarkable intermixture of palæozoic and mesozoic types which they exhibit. it is to be remembered, also, that this intermixture has hitherto been recognised, not in the middle triassic limestones of the muschelkalk, in which--as the oldest triassic beds with marine fossils--we should naturally expect to find it, but in the st cassian beds, the age of which is considerably later than that of the muschelkalk. the intermingling of old and new types of shell-fish in the upper trias is well brought out in the annexed table, given by sir charles lyell in his 'student's elements of geology' (some of the less important forms in the table being omitted here):-- genera of fossil mollusca in the st cassian and hallstadt beds. common to | characteristic of | common to older rocks. | triassic rocks | newer rocks. | | orthoceras. | ceratites. | ammonites. bactrites. | cochloceras. | chemnitzia. macrocheilus. | rhabdoceras. | cerithium. loxonema. | aulacoceras. | monodonta. holopella. | naticella. | sphoera. murchisonia. | platystoma. | cardita. porcellia. | halobia. | myoconcha. athyris. | hörnesia. | hinnites. retzia. | koninckia. | monotis. cyrtina. | scoliostoma. | plicatula. euomphalus. | myophoria. | pachyrisma. |(the last two are | thecidium. |principally but not | |exclusively triassic.)| thus, to emphasise the more important points alone, the trias has yielded, amongst the gasteropods, the characteristically palæozoic _loxonema, holopella, murchisonia, euomphalus_, and _porcellia_, along with typically triassic forms like _platystoma_ and _scoliostoma_, and the great modern groups _chemnitzia_ and _cerithium_. amongst the bivalves we find the palæozoic _megalodon_ side by side with the triassic _halobia_ and _myophoria_, these being associated with the _carditoe, hinnites, plicatuloe_, and _trigonioe_ of later deposits. the brachiopods exhibit the palæozoic _athyris, retzia_, and _cyrtina_, with the triassic _koninckia_ and the modern _thecidium_. finally, it is here that the ancient genera _orthoceras, cyrtoceras_, and _goniatites_ make their last appearance upon the scene of life, the place of the last of these being taken by the more complex and almost exclusively triassic _ceratites_, whilst the still more complex genus _ammonites_ first appears here in force, and is never again wanting till we reach the close of the mesozoic period. the first representatives of the great secondary family of the _belemnites_ are also recorded from this horizon. [illustration: fig. .--a, dental plate of _ceratodus serratus_, keuper; b, dental plate of _ceratodus altus_, keuper; (after agassiz.)] [illustration: fig .--_ceratodus fosteri_, the australian mud-fish, reduced in size.] amongst the _vertebrate animals_ of the trias, the _fishes_ are represented by numerous forms belonging to the _ganoids_ and the _placoids_. the ganoids of the period are still all provided with unsymmetrical ("heterocercal") tails, and belong principally to such genera as _paloeoniscus_ and _catopterus_. the remains of placoids are in the form of teeth and spines, the two principal genera being the two important secondary groups _acrodus_ and _hybodus_. very nearly at the summit of the trias in england, in the rhætic series, is a singular stratum, which is well known as the "bone-bed," from the number of fish-remains which it contains. more interesting, however, than the above, are the curious palate-teeth of the trias, upon which agassiz founded the genus _ceratodus_. the teeth of ceratodus (fig. ) are singular flattened plates, composed of spongy bone beneath, covered superficially with a layer of enamel. each plate is approximately triangular, one margin (which we now know to be the outer one) being prolonged into prongs or conical prominences, whilst the surface is more or less regularly undulated. until recently, though the master-mind of agassiz recognised that these singular bodies were undoubtedly the teeth of fishes, we were entirely ignorant as to their precise relation to the animal, or as to the exact affinities of the fish thus armed. lately, however, there has been discovered in the rivers of queensland (australia) a living species of _ceratodus_ (_c. fosteri_, fig. ), with teeth precisely similar to those of its triassic predecessor; and we thus have become acquainted with the use of these structures and the manner in which they were implanted in the mouth. the palate carries two of these plates, with their longer straight sides turned towards each other, their sharply-sinuated sides turned outwards, and their short straight sides or bases directed backwards. two similar plates in the lower jaw correspond to the upper, their undulated surfaces fitting exactly to those of the opposite teeth. there are also two sharp-edged front teeth, which are placed in the front of the mouth in the upper jaw; but these have not been recognised in the fossil specimens. the living _ceratodus_ feeds on vegetable matters, which are taken up or tom off from plants by the sharp front teeth, and then partially crushed between the undulated surfaces of the back teeth (günther); and there need be little doubt but that the triassic _ceratodi_ followed a similar mode of existence. from the study of the living _ceratodus_, it is certain that the genus belongs to the same group as the existing mud-fishes (_dipnoi_); and we therefore learn that this, the highest, group of the entire class of fishes existed in triassic times under forms little or not at all different from species now alive; whilst it has become probable that the order can be traced back into the devonian period. [illustration: fig. .--footprints of a labyrinthodont (_cheirotherium_), from the triassic sandstones of hessberg, near hildburghausen, germany, reduced one-eighth. the lower figure shows a slab, with several prints, and traversed by reticulated sun-cracks: the upper figure shows the impression of one of the hind-feet, one-half of the natural size. (after sickler.)] [illustration: fig. .--section of the tooth of _labryinthodon (mastodonsaurus) joegeri_, showing the microscopic structure. greatly enlarged. trias.] [illustration: fig. .--a, skull of _labyrinthodon joegeri_, much reduced in size; b, tooth of the same. trias württemberg.] the _amphibians_ of the trias all belong to the old order of the _labyrinthodonts_, and some of them are remarkable for their gigantic dimensions. they were first known by their footprints, which were found to occur plentifully in the triassic sandstones of britain and the continent of europe, and which consisted of a double series of alternately-placed pairs of hand-shaped impressions, the hinder print of each pair being much larger than the one in front (fig. ). so like were these impressions to the shape of the human hand, that the at that time unknown animal which produced them was at once christened _cheirotherium_, or "hand-beast." further discoveries, however, soon showed that the footprints of _cheirotherium_ were really produced by species of amphibians which, like the existing frogs, possessed hind-feet of a much larger size than the fore-feet, and to which the name of _labyrinthodonts_ was applied in consequence of the complex microscopic structure of the teeth (fig. ). in the essential details of their structure, the triassic labyrinthodonts did not differ materially from their predecessors in the coal-measures and permian rocks. they possessed the same frog-like skulls (fig. ), with a lizard-like body, a long tail, and comparatively feeble limbs. the hind-limbs were stronger and longer than the fore-limbs, and the lower surface of the body was protected by an armour of bony plates. some of the triassic labyrinthodonts must have attained dimensions utterly unapproached amongst existing amphibians, the skull of _labyrinthodon joegeri_ (fig. ) being upwards of three feet in length and two feet in breadth. restorations of some of these extraordinary creatures have been attempted in the guise of colossal frogs; but they must in reality have more closely resembled huge newts. remains of _reptiles_ are very abundant in triassic deposits, and belong to very varied types. the most marked feature, in fact, connected with the vertebrate fauna of the trias, and of the secondary rocks in general, is the great abundance of reptilian life. hence the secondary period is often spoken of as the "age of reptiles." many of the triassic reptiles depart widely in their structure from any with which we are acquainted as existing on the earth at the present day, and it is only possible here to briefly note some of the more important of these ancient forms. amongst the group of the lizards (_lacertilia_), represented by _protorosaurus_ in the older permian strata, three types more or less certainly referable to this order may be mentioned. one of these is a small reptile which was found many years ago in sandstones near elgin, in scotland, and which excited special interest at the time in consequence of the fact that the strata in question were believed to belong to the old red sandstone formation. it is, however, now certain that the elgin sandstones which contain _telerpeton elginense_, as this reptile is termed, are really to be regarded as of triassic age. by professor huxley, _telerpeton_ is regarded as a lizard, which cannot be considered as "in any sense a less perfectly-organised creature than the gecko, whose swift and noiseless run over walls and ceilings surprises the traveller in climates warmer than our own." the "elgin sandstones" have also yielded another lizard, which was originally described by professor huxley under the name of _hyperodapedon_, the remains of the same genus having been subsequently discovered in triassic strata in india and south africa. the lizards of this group must therefore have at one time enjoyed a very wide distribution over the globe; and the living _sphenodon_ of new zealand is believed by professor huxley to be the nearest living ally of this family. the _hyperodapedon_ of the elgin sandstones was about six feet in length, with limbs adapted for terrestrial progression, but with the bodies of the vertebræ slightly biconcave, and having two rows of palatal teeth, which become worn down to the bone in old age. lastly, the curious _rhynchosaurus_ of the trias is also referred, by the eminent comparative anatomist above mentioned, to the order of the lizards. in this singular reptile (fig. ) the skull is somewhat bird-like, and the jaws appear to have been destitute of teeth, and to have been encased in a horny sheath like the beak of a turtle or a bird. it is possible, however, that the palate was furnished with teeth. [illustration: fig. .--skull of _rhynchosaurus articeps_. trias. (after owen.)] the group of the crocodiles and alligators (_crocadilia_), distinguished by the fact that the teeth are implanted in distinct sockets and the skin more or less extensively provided with bony plates, is represented in the triassic rocks by the _stagonolepis_ of the elgin sandstones. the so-called "thecodont" reptiles (such as _belodon, thecodontosaurus_, and _paloeosaurus_, fig. , c, d, e) are also nearly related to the crocodiles, though it is doubtful if they should be absolutely referred to this group. in these reptiles, the teeth are implanted in distinct sockets in the jaws, their crowns being more or less compressed and pointed, "with trenchant and finely serrate margins" (owen). the bodies of the vertebræ are hollowed out at both ends, but the limbs appear to be adapted for progression on the land. the genus _belodon_ (fig. , c) is known to occur in the keuper of germany and in america; and _paloeosaurus_ (fig. . e) has also been found in the trias of the same region. teeth of the latter, however, are found, along with remains of _thecodontosaurus_ (fig. , d), in a singular magnesian conglomerate near bristol, which was originally believed to be of permian age, but which appears to be undoubtedly triassic. [illustration: fig. .--triassic reptiles. a, skull of _nothosaurus mirabilis_, reduced in size--muschelkalk, germany; b, tooth of _simosaurus gaillardoti_, of the natural size--muschelkalk, germany; c, tooth of _beladon carolinensis_--trias, america; d, tooth of _thecodontosaurus antiquus_, slightly enlarged--britain; e, tooth of _paloeosaurus platyodon_, of the natural size--britain.] the trias has also yielded the remains of the great marine reptiles which are often spoken of collectively as the "enaliosaurians" or "sea-lizards," and which will be more particularly spoken of in treating of the jurassic period, of which they are more especially characteristic. in all these reptiles the limbs are flattened out, the digits being enclosed in a continuous skin, thus forming powerful swimming-paddles, resembling the "flippers" of the whales and dolphins both in their general structure and in function. the tail is also long, and adapted to act as a swimming-organ; and there can be no doubt but that these extraordinary and often colossal reptiles frequented the sea, and only occasionally came to the land. the triassic enaliosaurs belong to a group of which the later genus _plesiosaurus_ is the type (the _sauropterygia_). one of the best known of the triassic genera is _nothosaurus_ (fig. , a), in which the neck was long and bird-like, the jaws being immensely elongated, and carrying numerous powerful conical teeth implanted in distinct sockets. the teeth in _simosaurus_ ( , b) are of a similar nature; but the orbits are of enormous size, indicating eyes of corresponding dimensions, and perhaps pointing to the nocturnal habits of the animal. in the singular _placodus_, again, the teeth are in distinct sockets, but resemble those of many fishes in being rounded and obtuse (fig. ), forming broad crushing plates adapted for the comminution of shell-fish. there is a row of these teeth all round the upper jaw proper, and a double series on the palate, but the lower jaw has only a single row of teeth. _placodus_ is found in the muschelkalk, and the characters of its dental apparatus indicate that it was much more peaceful in its habits than its associates the nothosaur and simosaur. [illustration: fig. .--under surface of the upper jaw and palate of _placodus gigas_. muschelkalk, germany.] the triassic rocks of south africa and india have yielded the remains of some extraordinary reptiles, which have been placed by professor owen in a separate order under the name of _anomodontia_. the two principal genera of this group are _dicynodon_ and _oudenodon_, both of which appear to have been large reptiles, with well-developed limbs, organised for progression upon the dry land. in _oudenodon_ (fig. , b) the jaws seem to have been wholly destitute of teeth, and must have been encased in a horny sheath, similar to that with which we are familiar in the beak of a turtle. in _dicynodon_ (fig. , a), on the other hand, the front of the upper jaw and the whole of the lower jaw were destitute of teeth, and the front of the mouth must have constituted a kind of beak; but the upper jaw possessed on each side a single huge conical tusk, which is directed downwards, and must have continued to grow during the life of the animal. [illustration: fig. .--triassic anomodont reptiles. a, skull of _dicynodon lacerticeps_, showing one of the great maxillary tusks; b, skull of _oudenodon bainii_, showing the toothless, beak-like jaws. from the trias of south africa. (after owen.)] it may be mentioned that the above-mentioned triassic sandstones of south africa have recently yielded to the researches of professor owen a new and unexpected type of reptile, which exhibits some of the structural peculiarities which we have been accustomed to regard as characteristic of the carnivorous quadrupeds. the reptile in question has been named _cyanodraco_, and it is looked upon by its distinguished discoverer as the type of a new order, to which he has given the name of _theriodontia_. the teeth of this singular form agree with those of the carnivorous quadrupeds in consisting of three distinct groups--namely, front teeth or _incisors_, eye teeth or _canines_, and back teeth or _molars_. the canines also are long and pointed, very much compressed, and having their lateral margins finely serrated, thus presenting a singular resemblance to the teeth of the extinct "sabre-toothed tiger" (_machairodus_). the bone of the upper arm (humerus) further shows some remarkable resemblances to the same bone in the carnivorous mammals. as has been previously noticed, professor owen is of opinion that some of the reptilian remains of the permian deposits will also be found to belong to this group of the "theriodonts." [illustration: fig. .--supposed footprint of a bird, from the triassic sandstones of the connecticut river. the slab shows also numerous "rain-prints."] lastly, we find in the triassic rocks the remains of reptiles belonging to the great mesozoic order of the _deinosauria_. this order attains its maximum at a later period, and will be spoken of when the jurassic and cretaceous deposits come to be considered. the chief interest of the triassic reptiles of this group arises from the fact that they are known by their footprints as well as by their bones; and a question has arisen whether the supposed footprints of _birds_ which occur in the trias have not really been produced by deinosaurs. this leads us, therefore, to speak at the same time as to the evidence which we have of the existence of the class of birds during the triassic period. no actual bones of any bird have as yet been detected in any triassic deposit; but we have tolerably clear evidence of their existence at this time in the form of _footprints_. the impressions in question are found in considerable numbers in certain red sandstones of the age of the trias in the valley of the connecticut river, in the united states. they vary much in size, and have evidently been produced by many different animals walking over long stretches of estuarine mud and sand exposed at low water. the footprints now under consideration form a double series of _single_ prints, and therefore, beyond all question, are the tracks of a _biped_--that is, of an animal which walked upon two legs. no living animals, save man and the birds, walk habitually on two legs; and there is, therefore, a _primâ facie_ presumption that the authors of these prints were birds. moreover, each impression consists of the marks of three toes turned forwards (fig. ), and therefore are precisely such as might be produced by wading or cursorial birds. further, the impressions of the toes show exactly the same numerical progression in the number of the joints as is observable in living birds--that is to say, the innermost of the three toes consists of three joints, the middle one of four, and the outer one of five joints. taking this evidence collectively, it would have seemed, until lately, quite certain that these tracks could only have been formed by birds. it has, however, been shown that the deinosaurian reptiles possess, in some cases at any rate, some singularly bird-like characters, amongst which is the fact that the animal possessed the power of walking, temporarily at least, on its hind-legs, which were much longer and stronger than the fore-limbs, and which were sometimes furnished with no more than three toes. as the bones and teeth of deinosaurs have been found in the triassic deposits of north america, it may be regarded as certain that _some_ of the bipedal tracks originally ascribed to birds must have really been produced by these reptiles. it seems at the same time almost a certainty that others of the three-toed impressions of the connecticut sandstones were in truth produced by birds, since it is doubtful if the bipedal mode of progression was more than an occasional thing amongst the deinosaurs, and the greater number of the many known tracks exhibit no impressions of fore-feet. upon the whole, therefore, we may, with much probability, conclude that the great class of birds (_aves_) was in existence in the triassic period. if this be so, not only must there have been quite a number of different forms, but some of them must have been of very large size. thus the largest footprints hitherto discovered in the connecticut sandstones are inches long and inches wide, with a proportionate length of stride. these measurements indicate a foot four times as large as that of the african ostrich; and the animal which produced them--whether a bird or a deinosaur--must have been of colossal dimensions. [illustration: fig. .--lower jaw of _dromatherium sylvestre_. trias, north carolina. (after emmons.)] [illustration: fig. .--a, molar tooth of _micro estes antiquus_, magnified; b, crown of the same, magnified still further. trias, germany.] [illustration: fig. .--the banded ant-eater (_myrmecobius fasciatus_) of australia.] finally, the trias completes the tale of the great classes of the vertebrate sub-kingdom by presenting us with remains of the first known of the true quadrupeds or _mammalia_. these are at present only known by their teeth, or, in one instance, by one of the halves of the lower jaw; and these indicate minute quadrupeds, which present greater affinities with the little banded anteater (_myrmecobius fasciatus_, fig. ) of australia than with any other living form. if this conjecture be correct, these ancient mammals belonged to the order of the marsupials or pouched quadrupeds (_marsupialia_), which are now exclusively confined to the australian province, south america, and the southern portion of north america. in the old world, the only known triassic mammals belong to the genus _microlestes_, and to the probably identical _hypsiprymnopsis_ of professor boyd dawkins. the teeth of _microlestes_ (fig. ) were originally discovered by plieninger in in the "bone-bed" which is characteristic of the summit of the rhætic series both in britain and on the continent of europe; and the known remains indicate two species. in britain, teeth of _microlestes_ have been discovered by mr charles moore in deposits of upper triassic age, filling a fissure in the carboniferous limestone near frome, in somersetshire; and a molar tooth of _hypsiprymnopsis_ was found by professor boyd dawkins in rhætic marls below the "bone-bed" at watchet, also in somersetshire. in north america, lastly, there has been found in strata of triassic age one of the branches of the lower jaw of a small mammal, which has been described under the name of _dromatherium sylvestre_ (fig. ). the fossil exhibits ten small molars placed side by side, one canine, and three incisors, separated by small intervals, and it indicates a small insectivorous animal, probably most nearly related to the existing _myrmecobius_. literature. the following list comprises a few of the more important sources of information as to the triassic strata and their fossil contents:-- ( ) 'geology of oxford and the valley of the thames.' phillips. ( ) 'memoirs of the geological survey of great britain and ireland.' ( ) 'report on the geology of londonderry,' &c. portlock. ( ) "on the zone of avicula contorta," &c.--'quart. journ. geol. soc.,' vol. xvi., . dr thomas wright. ( ) "on the zones of the lower lias and the avicula contorta zone"--'quart. journ. geol. soc.,' vol. xvii., . charles moore. ( ) "on abnormal conditions of secondary deposits," &c.--'quart. journ. geol. soc.,' vol. xxiii., - . charles moore. ( ) 'geognostische beschreibung des bayerischen alpengebirges.' gümbel. ( ) 'lethæa rossica.' pander. ( ) 'lethæa geognostica.' bronn. ( ) 'petrefacta germaniæ.' goldfuss. ( ) 'petrefaktenkunde.' quenstedt. ( ) 'monograph of the fossil estheriæ' (palæontographical society). rupert jones. ( ) "fossil remains of three distinct saurian animals, recently discovered in the magnesian conglomerate near bristol"--'trans. geol. soc.,' ser. , vol. v., . riley and stutchbury. ( ) 'die saurier des muschekalkes.' von meyer. ( ) 'beiträge zur palæontologie württembergs.' von meyer and plieninger. ( ) 'manual of palæontology.' owen. ( ) 'odontography:' owen. ( ) 'report on fossil reptiles' (british association, ). owen. ( ) "on dicynodon"--'trans. geol. soc.,' vol. iii., . owen. ( ) 'descriptive catalogue of fossil reptilia and fishes in the museum of the royal college of surgeons, england.' owen. ( ) "on species of labyrinthodon from warwickshire"--'trans. geol. soc.,' ser. , vol. vi. owen. ( ) "on a carnivorous reptile" (cynodraco major), &c.--'quart. journ. geol. soc.,' vol. xxxii., . owen. ( ) "on evidences of theriodonts in permian deposits," &c.--'quart. journ. geol. soc.,' vol. xxxii., . owen. ( ) "on the stagonolepis robertsoni," &c.--'quart. journ. geol. soc.,' vol. xv., . huxley. ( ) "on a new specimen of telerpeton elginense"--'quart. journ. geol. soc.,' vol. xxiii., . huxley. ( ) "on hyperodapedon"--'quart. journ. geol. soc.,' vol. xxv., . huxley. ( ) "on the affinities between the deinosaurian reptiles and birds"--'quart. journ. geol. soc.,' vol. xxvi., . huxley. ( ) "on the classification of the deinosauria," &c.--'quart. journ. geol. soc.,' vol. xxvi., . huxley. ( ) "palæontologica indica"--'memoirs of the geol. survey of india.' ( ) "on the geological position and geographical distribution of the dolomitic conglomerate of the bristol area"--'quart. journ. geol. soc.,' vol. xxvi., . r. etheridge, sen. ( ) "remains of labyrinthodonta from the keuper sandstone of warwick"--'quart. journ. geol. soc.,' vol. xxx., miall. ( ) 'manual of geology.' dana. ( ) 'synopsis of extinct batrachia and reptilia of north america.' cope. ( ) 'fossil footmarks.' hitchcock. ( ) 'ichnology of new england.' hitchcock. ( ) 'traité de paléontologie végétale.' schimper. ( ) 'histoire des végétaux fossiles.' brongniart. ( ) 'monographie der fossilen coniferen.' goeppert. chapter xvi. the jurassic period. resting upon the trias, with perfect conformity, and with an almost undeterminable junction, we have the great series of deposits which are known as the _oolitic rocks_, from the common occurrence in them of oolitic limestones, or as the _jurassic rocks_, from their being largely developed in the mountain-range of the jura, on the western borders of switzerland. sediments of this series occupy extensive areas in great britain, on the continent of europe, and in india. in north america, limestones and marls of this age have been detected in "the black hills, the laramie range, and other eastern ridges of the rocky mountains; also over the pacific slope, in the uintah, wahsatch, and humboldt mountains, and in the sierra nevada" (dana); but in these regions their extent is still unknown, and their precise subdivisions have not been determined. strata belonging to the jurassic period are also known to occur in south america, in australia, and in the arctic zone. when fully developed, the jurassic series is capable of subdivision into a number of minor groups, of which some are clearly distinguished by their mineral characters, whilst others are separated with equal certainty by the differences of the fossils that they contain. it will be sufficient for our present purpose, without entering into the more minute subdivisions of the series, to give here a very brief and general account of the main sub-groups of the jurassic rocks, as developed in britain--the arrangement of the jura-formation of the continent of europe agreeing in the main with that of england. i. the lias.--the base of the jurassic series of britain is formed by the great calcareo-argillaceous deposit of the "lias," which usually rests conformably and almost inseparably upon the rhætic beds (the so-called "white lias"), and passes up, generally conformably, into the calcareous sandstones of the inferior oolite. the lias is divisible into the three principal groups of the lower, middle, and upper lias, as under, and these in turn contain many well-marked "zones;" so that the lias has some claims to be considered as an independent formation, equivalent to all the remaining oolitic rocks. the _lower lias_ (_terrain sinemurien_ of d'orbigny) sometimes attains a thickness of as much as feet, and consists of a great series of bluish or greyish laminated clays, alternating with thin bands of blue or grey limestone--the whole, when seen in quarries or cliffs from a little distance, assuming a characteristically striped and banded appearance. by means of particular species of _ammonites_, taken along with other fossils which are confined to particular zones, the lower lias may be subdivided into several well-marked horizons. the _middle lias_, or _marlstone series_ (_terrain liasien_ of d'orbigny), may reach a thickness of feet, and consists of sands, arenaceous marls, and argillaceous limestones, sometimes with ferruginous beds. the _upper lias_ (_terrain toarcien_ of d'orbigny) attains a thickness of feet, and consists principally of shales below, passing upwards into arenaceous strata. ii. the lower oolites.--above the lias comes a complex series of partly arenaceous and argillaceous, but principally calcareous strata, of which the following are the more important groups: a, the _inferior oolite_ (_terrain bajocien_ of d'orbigny), consisting of more than feet of oolitic limestones, sometimes more or less sandy; b, the _fuller's earth_, a series of shales, clays, and marls, about feet in thickness; c, the _great oolite_ or _bath oolite_ (_terrain bathonien_ of d'orbigny), consisting principally of oolitic limestones, and attaining a thickness of about feet. the well-known "stonesfield slates" belong to this horizon; and the locally developed "bradford clay," "corn brash," and "forest-marble" may be regarded as constituting the summit of this group. iii. the middle oolites.--the central portion of the jurassic series of britain is formed by a great argillaceous deposit, capped by calcareous strata, as follows: a, the _oxford clay_ (_terrain callovien_ and _terrain oxfordien_ of d'orbigny), consisting of dark-coloured laminated clays, sometimes reaching a thickness of feet, and in places having its lower portion developed into a hard calcareous sandstone ("kelloway rock"); b, the coral-rag (_terrain corallien_ of d'orbigny, "nerinean limestone" of the jura, "diceras limestone" of the alps), consisting, when typically developed, of a central mass of oolitic limestone, underlaid and surmounted by calcareous grits. iv. the upper oolites.--a, the base of the upper oolites of britain is constituted by a great thickness ( feet or more) of laminated, sometimes carbonaceous or bituminous clays, which are known as the _kimmeridge clay_ (_terrain kimméridgien_ of d'orbigny); b, the _portland beds_ (_terrain portlandien_ of d'orbigny) succeed the kimmeridge clay, and consist inferiorly of sandy beds surmounted by oolitic limestones ("portland stone"), the whole series attaining a thickness of feet or more, and containing marine fossils; c, the _purbeck_ beds are apparently peculiar to great britain, where they form the summit of the entire oolitic series, attaining a total thickness of from to feet. the purbeck beds consist of arenaceous, argillaceous, and calcareous strata, which can be shown by their fossils to consist of a most remarkable alternation of fresh-water, brackish-water, and purely marine sediments, together with old land-surfaces, or vegetable soils, which contain the upright stems of trees, and are locally known as "dirt-beds." one of the most important of the jurassic deposits of the continent of europe, which is believed to be on the horizon of the coral-rag or of the lower part of the upper oolites, is the "_solenhofen slate_" of bavaria, an exceedingly fine-grained limestone, which is largely used in lithography, and is celebrated for the number and beauty of its organic remains, and especially for those of vertebrate animals. the subjoined sketch-section (fig. ) exhibits in a diagrammatic form the general succession of the jurassic rocks of britain. regarded as a whole, the jurassic formation is essentially marine; and though remains of drifted plants, and of insects and other air-breathing animals, are not uncommon, the fossils of the formation are in the main marine. in the purbeck series of britain, anticipatory of the great river-deposit of the wealden, there are fresh-water, brackish-water, and even terrestrial strata, indicating that the floor of the oolitic ocean was undergoing upheaval, and that the marine conditions which had formerly prevailed were nearly at an end. in places also, as in yorkshire and sutherlandshire, are found actual beds of coal: but the great bulk of the formation is an indubitable sea-deposit; and its limestones, oolitic as they commonly are, nevertheless are composed largely of the comminuted skeletons of marine animals. owing to the enormous number and variety of the organic remains which have been yielded by the richly fossiliferous strata of the oolitic series, it will not be possible here to do more than to give an outline-sketch of the principal forms of life which characterise the jurassic period as a whole. it is to be remembered, however, that every minor group of the jurassic formation has its own peculiar fossils, and that by the labours of such eminent observers as quenstedt, oppel, d'orbigny, wright, de la beche, tate, and others, the entire series of jurassic sediments admits of a more complete and more elaborate subdivision into zones characterised by special life-forms than has as yet been found practicable in the case of any other rock-series. [illustration: fig. . generalized section of the jurassic rocks of england.] [illustration: fig. .--_mantellia_ (_cycadeoidea_) _megalophylla_, a cycad from the purbeck "dirt-bed." upper oolites, england.] the _plants_ of the jurassic period consist principally of ferns, cycads, and conifers--agreeing in this respect, therefore, with those of the preceding triassic formation. the _ferns_ are very abundant, and belong partly to old and partly to new genera. the _cycads_ are also very abundant, and, on the whole, constitute the most marked feature of the jurassic vegetation, many genera of this group being known (_pterophyllum, otozamites, zamites, crossozamia, williamsonia, bucklandia,_ &c.) the so-called "dirt-bed" of the purbeck series consists of an ancient soil, in which stand erect the trunks of conifers and the silicified stools of cycads of the genus _mantellia_ (fig. ). the _coniferoe_ of the jurassic are represented by various forms more or less nearly allied to the existing _araucarioe_; and these are known not only by their stems or branches, but also in some cases by their cones. we meet, also, with the remains of undoubted endogenous plants, the most important of which are the fruits of forms allied to the existing screw-pines (_pandaneoe_), such as _podocarya_ and _kaidacarpum_. so far, however, no remains of palms have been found; nor are we acquainted with any jurassic plants which could be certainly referred to the great "angiospermous" group of the exogens, including the majority of our ordinary plants and trees. amongst animals, the _protozoans_ are well represented in the jurassic deposits by numerous _foraminifers_ and _sponges_; as are the _coelenterates_ by numerous _corals_. remains of these last-mentioned organisms are extremely abundant in some of the limestones of the formation, such as the "coral-rag" and the great oolite; and the former of these may fairly be considered as an ancient "reef." the _rugose corals_ have not hitherto been detected in the jurassic rocks; and the "_tabulate corals_," so-called, are represented only by examples of the modern genus _millepora_. with this exception, all the jurassic corals belong to the great group which predominates in recent seas (_zoantharia sclerodermata_); and the majority belong to the important reef-building family of the "star-corals" (_astroeidoe_). the form here figured (_thecosmilia annularis_, fig. ) is one of the characteristic species of the coral-rag. [illustration: fig. .--_thecosmilia annularis_, coral-rag, england.] [illustration: fig. .--_pentacrinus fasciculos_, lias. the left-hand figure shows a few or the joints of the column; the middle figure shows the arms, and the summit of the column with its side-arms; and the right-hand figure shows the articulating surface of one of the column-joints.] the _echinoderms_ are very numerous and abundant fossils in the jurassic series, and are represented by sea-lilies, sea-urchins, star-fishes, and brittle-stars. the _crinoids_ are still common, and some of the limestones of the series are largely composed of the _débris_ of these organisms. most of the jurassic forms resemble those with which we are already familiar, in having the body permanently attached to some foreign object by means of a longer or shorter jointed stalk or "column." one of the most characteristic jurassic genera of these "stalked" crinoids (though not exclusively confined to this period) is _pentacrinus_ (fig. ). in this genus, the column is five-sided, with whorls of "side-arms;" and the arms are long, slender, and branched. the genus is represented at the present day by the beautiful "medusa-head pentacrinite" (_pentacrinus caput-medusoe_). another characteristic oolitic genus is _apiocrinus_, comprising the so-called "pear encrinites." in this group the column is long and rounded, with a dilated base, and having its uppermost joints expanded so as to form, with the cup itself, a pear-shaped mass, from the summit of which spring the comparatively short arms. besides the "stalked" crinoids, the jurassic rocks have yielded the remains of the higher group of the "free" crinoids, such as _saccosoma_. these forms resemble the existing "feather-stars" (_comatula_) in being attached when young to some foreign body by means of a jointed stem, from which they detach themselves when fully grown to lead an independent existence. in this later stage of their life, therefore, they closely resemble the brittle-stars in appearance. true star-fishes (_asteroids_) and brittle-stars (_ophiuroids_) are abundant in the jurassic rocks, and the sea-urchins (_echinoids_) are so numerous and so well preserved as to constitute quite a marked feature of some beds of the series. all the oolitic urchins agree with the modern _echinoids_ in having the shell composed of no more than twenty rows of plates. many different genera are known, and a characteristic species of the middle oolites (_hemicidaris crenularis_, fig. ) is here figured. [illustration: fig. .--_hemicidaris crenularis_, showing the great tubercles on which the spines were supported. middle oolites.] passing over the _annelides_, which, though not uncommon, are of little special interest, we come to the _articulates_, which also require little notice. amongst the _crustaceans_, whilst the little water-fleas (_ostracoda_) are still abundant, the most marked feature is the predominance which is now assumed by the _decapods_--the highest of the known groups of the class. true crabs (_brachyura_) are by no means unknown; but the principal oolitic decapods belonged to the "long-tailed" group (_macrura_), of which the existing lobsters, prawns, and shrimps are members. the fine-grained lithographic slates of solenhofen are especially famous as a depot for the remains of these crustaceans, and a characteristic species from this locality (_eryon arctiformis_, fig. ) is here represented. amongst the air-breathing _articulates_, we meet in the oolitic rocks with the remains of spiders (_arachnida_), centipedes (_myriapoda_), and numerous true insects (_insecta_). in connection with the last-mentioned of these groups, it is of interest to note the occurrence of the oldest known fossil butterfly--the _paloeontina oolitica_ of the stonesfield slate--the relationships of which appear to be with some of the living butterflies of tropical america. [illustration: fig. .--_eryon arctiformis_, a "long-tailed decapod," from the middle oolites (solenhofen slate).] coming to the _mollusca_, the _polyzoans_, numerous and beautiful as they are, must be at once dismissed; but the _brachiopods_ deserve a moment's attention. the jurassic lamp-shells (fig. ) do not fill by any means such a predominant place in the marine fauna of the period, as in many palæozoic deposits, but they are still individually numerous. the two ancient genera _leptoena_ (fig. , a) and _spirifera_ (fig. , b), dating the one from the lower and the other from the upper silurian, appear here for the last time upon the scene, but they have not hitherto been recognised in deposits later than the lias. the great majority of the jurassic _brachiopods_, however, belong to the genera _terebratula_ (fig. , c, e, f) and _rhynchonella_ (fig. . d), both of which are represented by living forms at the present day. the _terebratuloe_, in particular, are very abundant, and the species are often confined to special horizons in the series. [illustration: fig. .--jurassic brachiopod. a. _leptoena liassica_, enlarged, the small cross below the figure indicating the true size of the shell--lias; b, _spirifera rostrata_, lias; c, _terebratula quadrifida_, lias; d, d', _rhynchonella varians_, fulter's earth and kelloway rock; e, _terebratula sphoeroidalis_, inferior oolite; f, _terebratula digona_, bradford clay, forest-marble, and great oolite. (after davidson).] [illustration: fig. .--_ostrea marshii_. middle and lower oolites.] [illustration: fig. .--_gryphoea incurva_. lias.] remains of _bivalves_ (_lamellibranchiata_) are very numerous in the jurassic deposits, and in many cases highly characteristic. in the marine beds of the oolites, which constitute by far the greater portion of the whole formation, the bivalyes are of course marine, and belong to such genera as _trigonia, lima, pholadomya, cardinia, avicula, hippopodium_, &c.; but in the purbeck beds, at the summit of the series, we find bands of oysters alternating with strata containing fresh-water or brackish-water bivalves, such as _cyrenoe_ and _corbuloe_. the predominant bivalves of the jurassic, however, are the _oysters_, which occur under many forms, and often in vast numbers, particular species being commonly restricted to particular horizons. thus of the true oysters, _ostrea distorta_ is characteristic of the purbeck series, where it forms a bed twelve feet in thickness, known locally as the "cinder-bed;" _ostrea expansa_ abounds in the portland beds; _ostrea deltoidea_ is characteristic of the kimmeridge clay; _ostrea gregaria_ predominates in the coral-rag; _ostrea acuminata_ characterises the small group of the fuller's earth; whilst the plaited _ostrea marshii_ (fig. ) is a common shell in the lower and middle oolites. besides the more typical oysters, the oolitic rocks abound in examples of the singularly unsymmetrical forms belonging to the genera _exogyra_ and _gryphoea_ (fig. ). in the former of these are included oysters with the beaks "reversed"--that is to say, turned towards the hinder part of the shell; whilst in the latter are oysters in which the lower valve of the shell is much the largest, and has a large incurved beak, whilst the upper valve is small and concave. one of the most characteristic _exogyroe_ is the _e. virgula_ of the oxford clay, and of the same horizon on the continent; and the _gryphoea incurva_ (fig. ) is equally abundant in, and characteristic of, the formation of the lias. lastly, we may notice the extraordinary shells belonging to the genus _diceras_ (fig. ), which are exclusively confined to the middle oolites. in this formation in the alps they occur in such abundance as to give rise to the name of "calcaire à dicerates," applied to beds of the same age as the coral-rag of britain. the genus _diceras_ belongs to the same family as the "thorny clams" (chama) of the present day--the shell being composed of nearly equally-sized valves, the beaks of which are extremely prominent and twisted into a spiral. the shell was attached to some foreign body by the beak of one of its valves. [illustration: fig. .--_diceras arietina_. middle oolite.] [illustration: fig. .--_nerinoea goodhallii_, one-fourth of the natural size. the left-hand figure shows the appearance presented by the shell when vertically divided. coral-rag, england.] amongst the jurassic univalves (_gasteropoda_) there are many examples of the ancient and long-lived _pleurotomaria_; but on the whole the univalves begin to have a modern aspect. the round-mouthed ("holostomatous"), vegetable-eating sea-snails, such as the limpets (_patellidoe_), the nerites (_nerita_), the _turritelloe, chemnitzioe_, &c., still hold a predominant place. the two most noticeable genera of this group are _cerithium_ and _nerinoea_--the former of these attaining great importance in the tertiary and recent seas, whilst the latter (fig. ) is highly characteristic of the jurassic series, though not exclusively confined to it. one of the limestones of the jura, believed to be of the age of the coral-rag (middle oolite) of britain, abounds to such an extent in the turreted shells of _nerinoea_ as to have gained the name of "calcaire à nérinées." in addition to forms such as the preceding, we now for the first time meet, in any force, with the carnivorous univalves, in which the mouth of the shell is notched or produced into a canal, giving rise to the technical name of "siphonostomatous" applied to the shell. some of the carnivorous forms belong to extinct types, such as the _purpuroidea_ of the great oolite; but others are referable to well-known existing genera. thus we meet here with species of the familiar groups of the whelks (_buccinum_), the spindle-shells (_fusus_), the spider-shells (_pteroceras_), _murex, rostellaria_, and others which are not at present known to occur in any earlier formation. amongst the wing-shells (_pteropoda_), it is sufficient to mark the final appearance in the lias of the ancient genus _conularia_. [illustration: fig. .--_ammonites humphresianus_. inferior oolite.] [illustration: fig. .--_ammonites bifrons_. lias.] lastly, the order of the _cephalopoda_, in both its tetrabranchiate and dibranchiate sections, undergoes a vast development in the jurassic period. the old and comparatively simple genus _nautilus_ is still well represented, one species being very similar to the living pearly nautilus (_n. pompilius_); but the _orthocerata_ and _goniatites_ of the trias have finally disappeared; and the great majority of the tetrabranchiate forms are referable to the comprehensive genus _ammonites_, with its many sub-genera and its hundreds of recorded species. the shell in _ammonites_ is in the form of a flat spiral, all the coils of which are in contact (figs. and ). the innermost whorls of the shell are more or less concealed; and the body-chamber is elongated and narrow, rather than expanded towards the mouth. the tube or siphuncle which runs through the air-chambers is placed on the dorsal or _convex_ side of the shell; but the principal character which distinguishes _ammonites_ from _goniatites_ and _ceratites_ is the wonderfully complex manner in which the _septa_, or partitions between the air-chambers, are folded and undulated. to such an extent does this take place, that the edges of the septa, when exposed by the removal of the shell-substance, present in an exaggerated manner the appearance exhibited by an elaborately-dressed shirt-frill when viewed edgewise. the species of _ammonites_ range from the carboniferous to the chalk; but they have not been found in deposits older than the secondary, in any region except india; and they are therefore to be regarded as essentially mesozoic fossils. within these limits, each formation is characterised by particular species, the number of individuals being often very great, and the size which is sometimes attained being nothing short of gigantic. in the lias, particular species of _ammonites_ may succeed one another regularly, each having a more or less definite horizon, which it does not transgress. it is thus possible to distinguish a certain number of zones, each characterised by a particular ammonite, together with other associated fossils. some of these zones are very persistent and extend over very wide areas, thus affording valuable aid to the geologist in his determination of rocks. it is to be remembered, however, that there are other species which are not thus restricted in their vertical range, even in the same formations in which definite zones occur. [illustartion: fig. .--_beloteuthis subcostata_ jurassic (lias).] the cuttle-fishes or _dibranchiate cephalopods_ constitute a feature in the life of the jurassic period little less conspicuous and striking than that afforded by the multitudinous and varied chambered shells of the _ammonitidoe_. the remains by which these animals are recognised are necessarily less perfect, as a rule, than those of the latter, as no external shell is present (except in rare and more modern groups), and the internal skeleton is not necessarily calcareous. nevertheless, we have an ample record of the cuttle-fishes of the jurassic period, in the shape of the fossilised jaws or beak, the ink-bag, and, most commonly of all, the horny or calcareous structure which is embedded in the soft tissues, and is variously known as the "pen" or "bone." the beaks of cuttle-fishes, though not abundant, are sufficiently plentiful to have earned for themselves the general title of "rhyncholites;" and in their form and function they resemble the horny, parrot-like beak of the existing cephalopods. the ink-bag or leathery sac in which the cuttle-fishes store up the black pigment with which they obscure the water when attacked, owes its preservation to the fact that the colouring-matter which it contains is finely-divided carbon, and therefore nearly indestructible except by heat. many of these ink-bags have been found in the lias; and the colouring-matter is sometimes so well preserved that it has been, as an experiment, employed in painting as a fossil "sepia." the "pens" of the cuttle-fishes are not commonly preserved, owing to their horny consistence, but they are not unknown. the form here figured (_beloteuthis subcostata_, fig. ) belonged to an old type essentially similar to our modern calamaries, the skeleton of which consists of a horny shaft and two lateral wings, somewhat like a feather in general shape. when, on the other hand, the internal skeleton is calcareous, then it is very easily preserved in a fossil condition; and the abundance of remains of this nature in the secondary rocks, combined with their apparent total absence in palæozoic strata, is a strong presumption in favour of the view that the order of the cuttle-fishes did not come into existence till the commencement of the mesozoic period. the great majority of the skeletons of this kind which are found in the jurassic rocks belong to the great extinct family of the "belemnites" (_belemnitidoa_), which, so far as known, is entirely confined to rocks of secondary age. from its pointed, generally cylindro-conical form, the skeleton of the belemnite is popularly known as a "thunderbolt". (fig. , c). in its perfect condition--in which it is, however, rarely obtainable--the skeleton consists of a chambered conical shell (the "phragmacone"), the partitions between the chambers of which are pierced by a marginal tube or "siphuncle." this conical shell--curiously similar in its structure to the _external_ shell of the nautilus--is extended forwards into a horny "pen," and is sunk in a corresponding conical pit (fig. , b), excavated in the substance of a nearly cylindrical fibrous body or "guard," which projects backwards for a longer or shorter distance, and is the part most usually found in a fossil condition. many different kinds of _belemnites_ are known, and their guards literally swarm in many parts of the jurassic series, whilst some specimens attain very considerable dimensions. not only is the internal skeleton known, but specimens of _belemnites_ and the nearly allied _belemnoteuthis_ have been found in some of the fine-grained sediments of the jurassic formation, from which much has been learnt even as to the anatomy of the soft parts of the animal. thus we know that the belemnites were in many respects comparable with the existing calamaries or squids, the body being furnished with lateral fins, and the head carrying a circle of ten "arms," two of which were longer than the others (fig. , a). the suckers on the arms were provided, further, with horny hooks; there was a large ink-sac; and the mouth was armed with horny mandibles resembling in shape the beak of a parrot. [illustration: fig. .--a, restoration of the animal of the belemnite; b, diagram showing the complete skeleton of a belemnite, consisting of the chambered phragmacone (a), the guard (b), and the horny pen (c); c, specimen of _belemnites canaliculatus_, from the inferior oolite. (after phillips.)] [illustration: fig. .--_tetragonolepis (restored), and scales of the same. lias.] coming next to the _vertebrates_, we find that the jurassic _fishes_ are still represented by _ganoids_ and _placoids_. the ganoids, however, unlike the old forms, now for the most part possess nearly or quite symmetrical ("homocercal") tails. a characteristic genus is _tetragonolepis_ (fig. ), with its deep compressed body, its rhomboidal, closely-fitting scales, and its single long dorsal fin. amongst the _placoids_ the teeth of true sharks (_notidanus_) occur for the first time; but by far the greater number of remains referable to this group are still the fin-spines and teeth of "cestracionts," resembling the living port-jackson shark. some of these teeth are pointed (_hybodus_); but others are rounded, and are adapted for crushing shell-fish. of these latter, the commonest are the teeth of _acrodus_ (fig. ), of which the hinder ones are of an elongated form, with a rounded surface, covered with fine transverse striæ proceeding from a central longitudinal line. from their general form and striation, and their dark colour, these teeth are commonly called "fossil leeches" by the quarrymen. [illustration: fig. .--tooth of _acrodus nobilis_. lias.] the amphibian group of the _labyrinthodonts_, which was so extensively developed in the trias, appears to have become extinct, no representative of the order having hitherto been detected in rocks of jurassic age. [illustration: fig. .--_ichthyosaurus communis. lias.] much more important than the fishes of the jurassic series are the _reptiles_, which are both very numerous, and belong to a great variety of types, some of these being very extraordinary in their anatomical structure. the predominant group is that of the "enaliosaurs" or "sea-lizards," divided into two great orders, represented respectively by the _ichthyosaurus_ and the _plesiosaurus_. the _ichthyosauri_ or "fish-lizards" are exclusively mesozoic in their distribution, ranging from the lias to the chalk, but abounding especially in the former. they were huge reptiles, of a fish-like form, with a hardly conspicuous neck (fig. ), and probably possessing a simply smooth or wrinkled skin, since no traces of scales or bony integumentary plates have ever been discovered. the tail was long, and was probably furnished at its extremity with a powerful expansion of the skin, constituting a tail-fin similar to that possessed by the whales. the limbs are also like those of whales in the essentials of their structure, and in their being adapted to act as swimming-paddles. unlike the whales, however, the ichthyosaurs possessed the hind-limbs as well as the fore-limbs, both pairs having the bones flattened out and the fingers completely enclosed in the skin, the arm and leg being at the same time greatly shortened. the limbs are thus converted into efficient "flippers," adapting the animal for an active existence in the sea. the different joints of the backbone (vertebræ) also show the same adaptation to an aquatic mode of life, being hollowed out at both ends, like the biconcave vertebræ of fishes. the spinal column in this way was endowed with the flexibility necessary for an animal intended to pass the greater part of its time in water. though the _ichthyosaurs_ are undoubtedly marine animals, there is, however, reason to believe that they occasionally came on shore, as they possess a strong bony arch, supporting the fore-limbs, such as would permit of partial, if laborious, terrestrial progression. the head is of enormous size, with greatly prolonged jaws, holding numerous powerful conical teeth lodged in a common groove. the nature of the dental apparatus is such as to leave no doubt as to the rapacious and predatory habits of the ichthyosaurs--an inference which is further borne out by the examination of their petrified droppings, which are known to geologists as "coprolites," and which contain numerous fragments of the bones and scales of the ganoid fishes which inhabited the same seas. the orbits are of huge size; and as the eyeball was protected, like that of birds, by a ring of bony plates in its outer coat, we even know that the pupils of the eyes were of correspondingly large dimensions. as these bony plates have the function of protecting the eye from injury under sudden changes of pressure in the surrounding medium, it has been inferred, with great probability, that the ichthyosaurs were in the habit of diving to considerable depths in the sea. some of the larger specimens of _ichthyosaurus_ which have been discovered in the lias indicate an animal of from to nearly feet in length; and many species are known to have existed, whilst fragmentary remains of their skeletons are very abundant in some localities. we may therefore safely conclude that these colossal reptiles were amongst the most formidable of the many tyrants of the jurassic seas. [illustration: fig. .--_plesiosaurus dolichodeirus_, restored. lias.] the _plesiosaurus_ (fig. ) is another famous oolitic reptile, and, like the preceding, must have lived mainly or exclusively in the sea. it agrees with the ichthyosaur in some important features of its organisation, especially in the fact that both pairs of limbs are converted into "flippers" or swimming-paddles, whilst the skin seems to have been equally destitute of any scaly or bony investiture. unlike the _ichthyosaur_, however, the plesiosaur had the paddles placed far back, the tail being extremely short, and the neck greatly lengthened out, and composed of from twenty to forty vertebræ. the bodies of the vertebræ, also, are not deeply biconcave, but are flat, or only slightly cupped. the head is of relatively small size, with smaller orbits than those of the _ichthyosaur_, and with a snout less elongated. the jaws, however, were armed with numerous conical teeth, inserted in distinct sockets. as regards the habits of the plesiosaur, dr conybeare arrives at the following conclusions: "that it was aquatic is evident from the form of its paddles; that it was marine is almost equally so from the remains with which it is universally associated; that it may have occasionally visited the shore, the resemblance of its extremities to those of the turtles may lead us to conjecture: its movements, however, must have been very awkward on land; and its long neck must have impeded its progress through the water, presenting a strong contrast to the organisation which so admirably fits the _ichthyosaurus_ to cut through the waves." as its respiratory organs were such that it must of necessity have required to obtain air frequently, we may conclude "that it swam upon or near the surface, arching back its long neck like a swan, and occasionally darting it down at the fish which happened to float within its reach. it may perhaps have lurked in shoal water along the coast, concealed amongst the sea-weed; and raising its nostrils to a level with the surface from a considerable depth, may have found a secure retreat from the assaults of powerful enemies; while the length and flexibility of its neck may have compensated for the want of strength in its jaws, and its incapacity for swift-motion through the water." about twenty species of _plesiosaurus_ are known, ranging from the lias to the chalk, and specimens have been found indicating a length of from eighteen to twenty feet. the nearly related "_pliosaurs_," however, with their huge heads and short necks, must have occasionally reached a length of at least forty feet--the skull in some species being eight, and the paddles six or seven feet long, whilst the teeth are a foot in length. [illustration: fig. .--_pterodactylus crassirostis_. from the lithographic slates of solenhofen (middle oolite). the figure is "restored," and it seems certain that the restoration is incorrect in the comparatively unimportant particular, that the hand should consist of no more than four fingers, three short and one long, instead of five, as represented.] another extraordinary group of jurassic reptiles is that of the "winged lizards" or _pterosauria_. these are often spoken of collectively as "pterodactyles," from _pterodactylus_, the type-genus of the group. as now restricted, however, the genus _pterodactylus_ is more cretaceous than jurassic, and it is associated in the oolitic rocks with the closely allied genera _dimorphodon_ and _rhamphorhynchus_. in all three of these genera we have the same general structural organisation, involving a marvellous combination of characters, which we are in the habit of regarding as peculiar to birds on the one hand, to reptiles on another hand, and to the flying mammals or bats in a third direction. the "pterosaurs" are "flying" reptiles, in the true sense of the term, since they were indubitably possessed of the power of active locomotion in the air, after the manner of birds. the so-called "flying" reptiles of the present day, such as the little _draco volans_ of the east indies and indian archipelago, possess, on the other hand, no power of genuine flight, being merely able to sustain themselves in the air through the extensive leaps which they take from tree to tree, the wing-like expansions of the skin simply exercising the mechanical function of a parachute. the apparatus of flight in the "pterosaurs" is of the most remarkable character, and most resembles the "wing" of a bat, though very different in some important particulars. the "wing" of the pterosaurs is like that of bats, namely, in consisting of a thin leathery expansion of the skin which is attached to the sides of the body, and stretches between the fore and hind limbs, being mainly supported by an enormous elongation of certain of the digits of the hand. in the bats, it is the four outer fingers which are thus lengthened out; but in the pterosaurs, the wing-membrane is borne by a single immensely-extended finger (fig. ). no trace of the actual wing-membrane itself has, of course, been found fossilised; but we could determine that the "pterodactyles" possessed the power of flight, quite apart from the extraordinary conformation of the hand. the proofs of this are to be found partly in the fact that the breast-bone was furnished with an elevated ridge or keel, serving for the attachment of the great muscles of flight, and still more in the fact that the bones were hollow and were filled with air--a peculiarity wholly confined amongst living animals to birds only. the skull of the pterosaurs is long, light, and singularly bird-like in appearance--a resemblance which is further increased by the comparative length of the neck and the size of the vertebræ of this region (fig. ). the jaws, however, unlike those of any existing bird, were, with one exception to be noticed hereafter, furnished with conical teeth sunk in distinct sockets; and there was always a longer or shorter tail composed of distinct vertebræ; whereas in all existing birds the tail is abbreviated, and the terminal vertebræ are amalgamated to form a single bone, which generally supports the great feathers of the tail. modern naturalists have been pretty generally agreed that the _pterosaurs_ should be regarded as a peculiar group of the reptiles; though they have been and are still regarded by high authorities, like professor seeley, as being really referable to the birds, or as forming a class by themselves. the chief points which separate them from birds, as a class, are the character of the apparatus of flight, the entirely different structure of the fore-limb, the absence of feathers, the composition of the tail out of distinct vertebræ, and the general presence of conical teeth sunk in distinct sockets in the jaws. the gap between the pterosaurs and the birds has, however, been greatly lessened of late by the discovery of fossil animals (_ichthyornis_ and _hesperornis_) with the skeleton proper to birds combined with the presence of teeth in the jaws, and by the still more recent discovery of other fossil animals (_pteranodon_) with a pterosaurian skeleton, but without teeth; whilst the undoubtedly feathered _archoeopteryx_ possessed a long tail composed of separate vertebræ. upon the whole, therefore, the relationships of the pterosaurs cannot be regarded as absolutely settled. it seems certain, however, that they did not possess feathers--this implying that they were cold-blooded animals; and their affinities with reptiles in this, as in other characters, are too strong to be overlooked. [illustration: fig. --_rhamphorhynchus bucklandi_, restored. bath oolite, england. (after the late professor phillips.)] the _pterosaurs_ are wholly mesozoic, ranging from the lias to the chalk inclusive; and the fine-grained lithographic slate of solenhofen has proved to be singularly rich in their remains. the genus _pterodactylus_ itself has the jaws toothed to the extremities with equal-sized conical teeth, and its species range from the middle oolites to the cretaceous series, in connection with which they will be again noticed, together with the toothless genus _pteranodon_. the genus _dimorphodon_ is liassic, and is characterised by having the front teeth long and pointed, whilst the hinder teeth are small and lancet-shaped. lastly, the singular genus _rhamphorhynchus_, also from the lower oolites, is distinguished by the fact that there are teeth present in the hinder portions of both jaws; but the front portions are toothless, and may have constituted a horny beak. like most of the other jurassic pterosaurs, _rhamphorhynchus_ (fig. ) does not seem to have been much bigger than a pigeon, in this respect falling far below the giant "dragons" of the cretaceous period. it differed from its relatives, not only in the armature of the mouth, but also in the fact that the tail was of considerable length. with regard to its habits and mode of life, professor phillips remarks that, "gifted with ample means of flight, able at least to perch on rocks and scuffle along the shore, perhaps competent to dive, though not so well as a palmiped bird, many fishes must have yielded to the cruel beak and sharp teeth of rhamphorhynchus. if we ask to which of the many families of birds the analogy of structure and probable way of life would lead us to assimilate rhamphorhynchus, the answer must point to the swimming races with long wings, clawed feet, hooked beak, and habits or violence and voracity; and for preference, the shortness of the legs, and other circumstances, may be held to claim for the stonesfield fossil a more than fanciful similitude to the groups of cormorants, and other marine divers, which constitute an effective part of the picturesque army of robbers of the sea." another extraordinary and interesting group of the mesozoic reptiles is constituted by the _deinosauria_, comprising a series of mostly gigantic forms, which range from the trias to the chalk. all the "deinosaurs" are possessed of the two pairs of limbs proper to vertebrate animals, and these organs are in the main adapted for walking on the dry land. thus, whilst the mesozoic seas swarmed with the huge ichthyosaurs and plesiosaurs, and whilst the air was tenanted by the dragon-like pterosaurs, the land-surfaces of the secondary period were peopled by numerous forms of deinosaurs, some of them of even more gigantic dimensions than their marine brethren. the limbs of the _deinosaurs_ are, as just said, adapted for progression on the land; but in some cases, at any rate, the hind-limbs were much longer and stronger than the fore-limbs; and there seems to be no reason to doubt that many of these forms possessed the power of walking, temporarily or permanently, on their hind-legs, thus presenting a singular resemblance to birds. some very curious and striking points connected with the structure of the skeleton have also been shown to connect these strange reptiles with the true birds; and such high authorities as professors huxley and cope are of opinion that the deinosaurs are distinctly related to this class, being in some respects intermediate between the proper reptiles and the great wingless birds, like the ostrich and cassowary. on the other hand, professor owen has shown that the deinosaurs possess some weighty points of relationship with the so-called "pachydermatous" quadrupeds, such as the rhinoceros and hippopotamus. the most important jurassic genera of _deinosauria_ are _megalosaurus_ and _cetiosaurus_, both of which extend their range into the cretaceous period, in which flourished, as we shall see, some other well-known members of this order. [illustration: fig. .--skull of _megalosaurus_, on a scale one-tenth of nature. restored. (after professor phillips.)] _megalosaurus_ attained gigantic dimensions, its thigh and shank bones measuring each about three feet in length, and its total length, including the tail, being estimated at from forty to fifty feet. as the head of the thigh-bone is set on nearly at right angles with the shaft, whilst all the long bones of the skeleton are hollowed out internally for the reception of the marrow, there can be no doubt as to the terrestrial habits of the animal. the skull (fig. ) was of large size, four or five feet in length, and the jaws were armed with a series of powerful pointed teeth. the teeth are conical in shape, but are strongly compressed towards their summits, their lateral edges being finely serrated. in their form and their saw-like edges, they resemble the teeth of the "sabre-toothed tiger" (_machairodus_), and they render it certain that the megalosaur was in the highest degree destructive and carnivorous in its habits. so far as is known, the skin was not furnished with any armour of scales or bony plates; and the fore-limbs are so disproportionately small as compared with the hind-limbs, that this huge reptile--like the equally huge iguanodon--may be conjectured to have commonly supported itself on its hind-legs only. the _cetiosaur_ attained dimensions even greater than those of the megalosaur, one of the largest thigh-bones measuring over five feet in length and a foot in diameter in the middle, and the total length of the animal being probably not less than fifty feet. it was originally regarded as a gigantic crocodile, but it has been shown to be a true deinosaur. having obtained a magnificent series of remains of this reptile, professor phillips has been able to determine many very interesting points as to the anatomy and habits of this colossal animal, the total length of which he estimates as being probably not less than sixty or seventy feet. as to its mode of life, this accomplished writer remarks:-- "probably when 'standing at ease' not less than ten feet in height, and of a bulk in proportion, this creature was unmatched in magnitude and physical strength by any of the largest inhabitants of the mesozoic land or sea. did it live in the sea, in fresh waters, or on the land? this question cannot be answered, as in the case of ichthyosaurus, by appeal to the accompanying organic remains; for some of the bones lie in marine deposits, others in situations marked by estuarine conditions, and, out of the oxfordshire district, in sussex, in fluviatile accumulations. was it fitted to live exclusively in water? such an idea was at one time entertained, in consequence of the biconcave character of the caudal vertebræ, and it is often suggested by the mere magnitude of the creature, which would seem to have an easier life while floating in water, than when painfully lifting its huge bulk, and moving with slow steps along the ground. but neither of these arguments is valid. the ancient earth was trodden by larger quadrupeds than our elephant; and the biconcave character of vertebræ, which is not uniform along the column in cetiosaurus, is perhaps as much a character of a geological period as of a mechanical function of life. good evidence of continual life in water is yielded in the case of ichthyosaurus and other enaliosaurs, by the articulating surfaces of their limb-bones, for these, all of them, to the last phalanx, have that slight and indefinite adjustment of the bones, with much intervening cartilage, which fits the leg to be both a flexible and forcible instrument of natation, much superior to the ordinary oar-blade of the boatman. on the contrary, in cetiosaur, as well as in megalosaur and iguanodon, all the articulations are definite, and made so as to correspond to determinate movements in particular directions, and these are such as to be suited for walking. in particular, the femur, by its head projecting freely from the acetabulum, seems to claim a movement of free stepping more parallel to the line of the body, and more approaching to the vertical than the sprawling gait of the crocodile. the large claws concur in this indication of terrestrial habits. but, on the other hand, these characters are not contrary to the belief that the animal may have been amphibious; and the great vertical height of the anterior part of the tail seems to support this explanation, but it does not go further.... we have therefore a marsh-loving or river-side animal, dwelling amidst filicine, cycadaceous, and coniferous shrubs and trees full of insects and small mammalia. what was its usual diet? if _ex ungue leonem_, surely _ex dente cibum_. we have indeed but one tooth, and that small and incomplete. it resembles more the tooth of iguanodon than that of any other reptile; for this reason it seems probable that the animal was nourished by similar vegetable food which abounded in the vicinity, and was not obliged to contend with megalosaurus for a scanty supply of more stimulating diet." all the groups of jurassic reptiles which we have hitherto been considering are wholly unrepresented at the present day, and do not even pass upwards into the tertiary period. it may be mentioned, however, that the oolitic deposits have also yielded the remains of reptiles belonging to three of the existing orders of the class-namely, the lizards (_lacertilia_), the turtles (_chelonia_), and the crocodiles (_crocodilia_). the lizards occur both in the marine strata of the middle oolites and also in the fresh-water beds of the purbeck series; and they are of such a nature that their affinities with the typical lacertilians of the present day cannot be disputed. the chelonians, up to this point only known by the doubtful evidence of footprints in the permian and triassic sandstones, are here represented by unquestionable remains, indicating the existence of marine turtles (the _chelone planiceps_ of the portland stone). no remains of serpents (_ophidians_) have as yet been detected in the jurassic; but strata of this age have yielded the remains of numerous _crocodilians_, which probably inhabited the sea. the most important member of this group is _teleosaurus_, which attained a length of over thirty feet, and is in some respects allied to the living gavials of india. [illustration: fig. .--_archoeopteryx macrura_, showing tail and tail-feathers, with detached bones. reduced. from the lithographic slate of solenhofen.] [illustration: fig. .--restoration of _archoeopteryx macrura_. (after owen.)] the great class of the birds, as we have seen, is represented in rocks earlier than the oolites simply by the not absolutely certain evidence of the three-toed footprints of the connecticut trias. in the lithographic slate of solenhofen (middle oolite), there has been discovered, however, the at present unique skeleton of a bird well known under the name of the _archoeopteryx macrura_ (figs. , ). the only known specimen--now in the british museum--unfortunately does not exhibit the skull; but the fine-grained matrix has preserved a number of the other bones of the skeleton, along with the impressions of the tail and wing feathers. from these remains we know that _archoeopteryx_ differed in some remarkable peculiarities of its structure from all existing members of the class of birds. this extraordinary bird (fig. ) appears to have been about as big as a rook--the tail being long and extremely slender, and composed of separate vertebræ, each of which supports a single pair of quill-feathers. in the flying birds of the present day, as before mentioned, the terminal vertebræ of the tail are amalgamated to form a single bone ("ploughshare-bone"), which supports a cluster of tail-feathers; and the tail itself is short. in the embryos of existing birds the tail is long, and is made up of separate vertebræ, and the same character is observed in many existing reptiles. the tail of _archoeopteryx_, therefore, is to be regarded as the permanent retention of an embryonic type of structure, or as an approximation to the characters of the reptiles. another remarkable point in connection with _archoeopteryx_, in which it differs from all known birds, is, that the wing was furnished with two free claws. from the presence of feathers, _archoeopteryx_ may be inferred to have been hot-blooded; and this character, taken along with the structure of the skeleton of the wing, may be held as sufficient to justify its being considered as belonging to the class of birds. in the structure of the tail, however, it is singularly reptilian; and there is reason to believe that its jaws were furnished with teeth sunk in distinct sockets, as is the case in no existing bird. this conclusion, at any rate, is rendered highly probable by the recent discovery of "toothed birds" (_odonturnithes_) in the cretaceous rocks of north america. [illustration: fig. .--lower jaw of _amphitherium_ (_thylacotherium_) _prevostii_. stonesfield slate (great oolite.)] [illustration: fig. . oolitic mammals.-- , lower jaw and teeth of _phascolotherium_, stonesfield slate; , lower jaw and teeth of _amphitherium_, stonesfield slate; , lower jaw and teeth of _triconodon_, purbeck beds; , lower jaw and teeth of _plagiaulax_, purbeck beds. all the figures are of the natural size.] the _mammals_ of the jurassic period are known to us by a number of small forms which occur in the "stonesfield slate" (great oolite) and in the purbeck beds (upper oolite). the remains of these are almost exclusively separated halves of the lower jaw, and they indicate the existence during the oolitic period in europe of a number of small "pouched animals" (_marsupials_). in the horizon of the stonesfield slate four genera of these little quadrupeds have been described--viz., _amphilestes, amphitherium, phascolotherium_, and _stereognathus_. in _amphitherium_ (fig. ), the molar teeth are furnished with small pointed eminences or "cusps;" and the animal was doubtless insectivorous. by professor owen, the highest living authority on the subject, _amphitherium_ is believed to be a small marsupial, most nearly allied to the living banded ant-eater (_myrmecobius_) of australia (fig. ). _amphilestes_ and _phascolotherium_ (fig. ) are also believed by the same distinguished anatomist and palæontologist to have been insect-eating marsupials, and the latter is supposed to find its nearest living ally in the opossums (_didelphys_) of america. lastly, the _stereognathus_ of the stonesfield slate is in a dubious position. it may have been a marsupial; but, upon the whole, professor owen is inclined to believe that it must have been a hoofed and herbivorous quadruped belonging to the series of the higher mammals (_placentalia_). in the middle purbeck beds, near to the close of the oolitic period, we have also evidence of the existence of a number of small mammals, all of which are probably marsupials. fourteen species are known, all of small size, the largest being no bigger than a polecat or hedgehog. the genera to which these little quadrupeds have been referred are _plagiaulax, spalacotherium, triconodon_, and _galestes_. the first of these (fig. , ) is believed by professor owen to have been carnivorous in its habits; but other authorities maintain that it was most nearly allied to the living kangaroo-rats (_hypsiprymnus_) of australia, and that it was essentially herbivorous. the remaining three genera appear to have been certainly insectivorous, and find their nearest living representatives in the australian phalangers and the american opossums. finally, it is interesting to notice in how many respects the jurassic fauna of western europe approached to that now inhabiting australia. at the present day, australia is almost wholly tenanted by marsupials; upon its land-surface flourish _araucarioe_ and cycadaceous plants, and in its seas swims the port-jackson shark (_cestracion philippi_); whilst the molluscan genus _trigonia_ is nowadays exclusively confined to the australian coasts. in england, at the time of the deposition of the jurassic rocks, we must have had a fauna and flora very closely resembling what we now see in australia. the small marsupials, _amphitherium, phascolotherium_, and others, prove that the mammals were the same in order; cones of araucarian pines, with tree-ferns and fronds of cycads, occur throughout the oolitic series; spine-bearing fishes, like the port-jackson shark, are abundantly represented by genera such as _acrodus_ and _strophodus_; and lastly, the genus _trigonia_, now exclusively australian, is represented in the oolites by species which differ little from those now existing. moreover, the discovery during recent years of the singular mud-fish, the _ceratodus fosteri_ in the rivers of queensland, has added another and a very striking point of resemblance to those already mentioned; since this genus of fishes, though preeminently triassic, nevertheless extended its range into the jurassic. upon the whole, therefore, there is reason to conclude that australia has undergone since the close of the jurassic period fewer changes and vicissitudes than any other known region of the globe; and that this wonderful continent has therefore succeeded in preserving a greater number of the characteristic life-features of the oolites than any other country with which we are acquainted. literature. the following list comprises some of the more important sources of information as to the rocks and fossils of the jurassic series:-- ( ) 'geology of oxford and the thames valley.' phillips. ( ) 'geology of yorkshire,' vol. ii. phillips. ( ) 'memoirs of the geological survey of great britain.' ( ) 'geology of cheltenham.' murchison, d ed. buckman. ( ) 'introduction to the monograph of the oolitic asteriadæ' (palæontographical society). wright. ( ) "zone of avicula contorta and the lower lias of the south of england"--'quart. journ. geol. soc.,' vol. xvi., . wright. ( ) "oolites of northamptonshire"--'quart. journ. geol. soc.,' vols. xxvi. and xxix. sharp. ( ) 'manual of geology.' dana. ( ) 'der jura.' quenstedt. ( ) 'das flötzgebirge württembergs.' quenstedt. ( ) 'jura formation.' oppel. ( ) 'paléontologie du département de la moselle.' terquem. ( ) 'cours élémentaire de paléontologie.' d'orbigny. ( ) 'paléontologie française.' d'orbigny. ( ) 'fossil echinodermata of the oolitic formation' (palæontographical society). wright. ( ) 'brachiopoda of the oolitic formation' (palæontographical society). davidson. ( ) 'mollusca of the great oolite' (palæontographical society). morris and lycett. ( ) 'monograph of the fossil trigoniæ' (palæontographical society). lycett. ( ) 'corals of the oolitic formation' (palæontographical society). edwards and haime. ( ) 'supplement to the corals of the oolitic formation' (palæontographical society). martin duncan. ( ) 'monograph of the belemnitidæ' (palæontographical society). phillips. ( ) 'structure of the belemnitidæ' (mem. geol. survey). huxley. ( ) 'sur les belemnites.' blainville. ( ) 'cephalopoden.' quenstedt. ( ) 'mineral conchology.' sowerby. ( ) 'jurassic cephalopoda' (palæontologica indica). waagen. ( ) 'manual of the mollusca.' woodward. ( ) 'petrefaktenkunde.' schlotheim. ( ) 'bridgewater treatise.' buckland. ( ) 'versteinerungen des oolithengebirges.' roemer. ( ) 'catalogue of british fossils.' morris. ( ) 'catalogue of fossils in the museum of practical geology.' etheridge. ( ) 'beiträge zur petrefaktenkunde.' münster. ( ) 'petrefacta germaniæ.' goldfuss. ( ) 'lethæa rossica.' eichwald. ( ) 'fossil fishes' (decades of the geol. survey). sir philip egerton. ( ) 'manual of palæontology.' owen. ( ) 'british fossil mammals and birds.' owen. ( ) 'monographs of the fossil reptiles of the oolitic formation' (palæontographical society). owen. ( ) 'fossil mammals of the mesozoic formations' (palæontographical society). owen. ( ) 'catalogue of ornithosauria.' seeley. ( ) "classification of the deinosauria"--'quart. journ. geol. soc.,' vol. xxvi., . huxley. chapter xvii. the cretaceous period. the next series of rocks in ascending order is the great and important series of the cretaceous rocks, so called from the general occurrence in the system of chalk (lat. _creta_, chalk). as developed in britain and europe generally, the following leading subdivisions may be recognised in the cretaceous series:-- . wealden, \_ lower cretaceous. . lower greensand or neocomian, / . gault, \ . upper greensand, |_ upper cretaceous. . chalk, | . maestricht beds, / i. _wealden_.--the _wealden_ formation, though of considerable importance, is a local group, and is confined to the southeast of england, france, and some other parts of europe. its name is derived from the _weald_, a district comprising parts of surrey, sussex, and kent, where it is largely developed. its lower portion, for a thickness of from to feet, is arenaceous, and is known as the hastings sands. its upper portion, for a thickness of to nearly feet, is chiefly argillaceous, consisting of clays with sandy layers, and occasionally courses of limestone. the geological importance of the wealden formation is very great, as it is undoubtedly the delta of an ancient river, being composed almost wholly of fresh-water beds, with a few brackish-water and even marine strata, intercalated in the lower portion. its geographical extent, though uncertain, owing to the enormous denudation to which it has been subjected, is nevertheless great, since it extends from dorsetshire to france, and occurs also in north germany. still, even if it were continuous between all these points, it would not be larger than the delta of such a modern river as the ganges. the river which produced the wealden series must have flowed from an ancient continent occupying what is now the atlantic ocean; and the time occupied in the formation of the wealden must have been very great, though we have, of course, no data by which we can accurately calculate its duration. the fossils of the wealden series are, naturally, mostly the remains of such animals as we know at the present day as inhabiting rivers. we have, namely, fresh-water mussels (_unio_), river-snails (_paludina_), and other fresh-water shells, with numerous little bivalved crustaceans, and some fishes. ii. _lower greensand_ (_néocomien_ of d'orbigny).--the wealden beds pass upward, often by insensible gradations, into the lower greensand. the name lower greensand is not an appropriate one, for green sands only occur sparingly and occasionally, and are found in other formations. for this reason it has been proposed to substitute for lower greensand the name _neocomian_, derived from the town of neufchâtel--anciently called _neocomum_--in switzerland. if this name were adopted, as it ought to be, the wealden beds would be called the lower neocomian. the lower greensand or neocomian of britain has a thickness of about feet, and consists of alternations of sands, sandstones, and clays, with occasional calcareous bands. the general colour of the series is dark brown, sometimes red; and the sands are occasionally green, from the presence of silicate of iron. the fossils of the lower greensand are purely marine, and among the most characteristic are the shells of _cephalopods_. the most remarkable point, however, about the fossils of the lower cretaceous series, is their marked divergence from the fossils of the upper cretaceous rocks. of species of fossils in the lower cretaceous series, only , or about per cent, pass on into the upper cretaceous. this break in the life of the two periods is accompanied by a decided physical break as well; for the gault is often, if not always, unconformably superimposed on the lower greensand. at the same time, the lower and upper cretaceous groups form a closely-connected and inseparable series, as shown by a comparison of their fossils with those of the underlying jurassic rocks and the overlying tertiary beds. thus, in britain no marine fossil is known to be common to the marine beds of the upper oolites and the lower greensand; and of more than species of fossils in the upper cretaceous rocks, almost everyone died out before the formation of the lowest tertiary strata, the only survivors being one brachiopod and a few _foraminifera_. iii. _gault_ (_aptien_ of d'orbigny).--the lowest member of the upper cretaceous series is a stiff, dark-grey, blue, or brown clay, often worked for brick-making, and known as the _gault_, from a provincial english term. it occurs chiefly in the south-east of england, but can be traced through france to the flanks of the alps and bavaria. it never exceeds feet in thickness; but it contains many fossils, usually in a state of beautiful preservation. iv. _upper greensand_ (_albien_ of d'orbigny; _unterquader_ and _lower plänerkalk_ of germany).--the gault is succeeded upward by the _upper greensand_, which varies in thickness from up to feet, and which derives its name from the occasional occurrence in it of green sands. these, however, are local and sometimes wanting, and the name "upper greensand" is to be regarded as a _name_ and not a description. the group consists, in britain, of sands and clays, sometimes with bands of calcareous grit or siliceous limestone, and occasionally containing concretions of phosphate of lime, which are largely worked for agricultural purposes. v. _white chalk_.--the top of the upper greensand becomes argillaceous, and passes up gradually into the base of the great formation known as the true _chalk_, divided into the three subdivisions of the chalk-marl, white chalk without flints, and white chalk with flints. the first of these is simply argillaceous chalk, and passes up into a great mass of obscurely-stratified white chalk in which there are no flints (_turonien_ of d'orbigny; _mittelquader_ of germany). this, in turn, passes up into a great mass of white chalk, in which the stratification is marked by nodules of black flint arranged in layers (_sénonien_ of d'orbigny; _oberquader_ of germany). the thickness of these three subdivisions taken together is sometimes over feet, and their geographical extent is very great. white chalk, with its characteristic appearance, may be traced from the north of ireland to the crimea, a distance of about geographical miles; and, in an opposite direction, from the south of sweden to bordeaux, a distance of about geographical miles. vi. in britain there occur no beds containing chalk fossils, or in any way referable to the cretaceous period, above the true white chalk with flints. on the banks of the maes, however, near maestricht in holland, there occurs a series of yellowish limestones, of about feet in thickness, and undoubtedly superior to the white chalk. these _maestricht beds_ (_danien_ of d'orbigny) contain a remarkable series of fossils, the characters of which are partly cretaceous and partly tertiary. thus, with the characteristic chalk fossils, _belemnites, baculites_, sea-urchins, &c., are numerous univalve molluscs, such as cowries and volutes, which are otherwise exclusively tertiary or recent. holding a similar position to the maestricht beds, and showing a similar intermixture of cretaceous forms with later types, are certain beds which occur in the island of seeland, in denmark, and which are known as the _faxöe limestone_. of a somewhat later date than the maestricht beds is the _pisolitic limestone_ of france, which rests unconformably on the white chalk, and contains a large number of tertiary fossils along with some characteristic cretaceous types. the subjoined sketch-section exhibits the general succession of the cretaceous deposits in britain:-- [illustration: fig. . generalized section of the cretaceous series of britain.] in north america, strata of lower cretaceous age are well represented in missouri, wyoming, utah, and in some other areas; but the greater portion of the american deposits of this period are referable to the upper cretaceous. the rocks of this series are mostly sands, clays, and limestones--_chalk_ itself being unknown except in western arkansas. amongst the sandy accumulations, one of the most important is the so-called "marl" of new jersey, which is truly a "greensand," and contains a large proportion of glauconite (silicate of iron and potash). it also contains a little phosphate of lime, and is largely worked for agricultural purposes. the greatest thickness attained by the cretaceous rocks of north america is about feet, as in wyoming, utah, and colorado. according to dana, the cretaceous rocks of the rocky mountain territories pass upwards "without interruption into a coal-bearing formation, several thousand feet thick, on which the following tertiary strata lie unconformably." the lower portion of this "lignitic formation" appears to be cretaceous, and contains one or more beds of coal; but the upper part of it perhaps belongs to the lower tertiary. in america, therefore, the lowest tertiary strata appear to rest conformably upon the highest cretaceous; whereas in europe, the succession at this point is invariably an unconformable one. owing, however, to the fact that the american "lignitic formation" is a shallow-water formation, it can hardly be expected to yield much material whereby to bridge over the great palæontological gap between the white chalk and eocene in the old world. owing to the fact that so large a portion of the cretaceous formation has been deposited in the sea, much of it in deep water, the _plants_ of the period have for the most part been found special members of the series, such as the wealden beds, the aix-la-chapelle sands, and the lignitic beds of north america. even the purely marine strata, however, have yielded plant-remains, and some of these are peculiar and proper to the deep-sea deposits of the series. thus the little calcareous discs termed "coccoliths," which are known to be of the nature of calcareous sea-weeds (_algoe_) have been detected in the white chalk; and the flints of the same formation commonly contain the spore-cases of the microscopic _desmids_ (the so-called xanthidia), along with the siliceous cases of the equally diminutive _diatoms_. the plant-remains of the lower cretaceous greatly resemble those of the jurassic period, consisting mainly of ferns, cycads, and conifers. the upper cretaceous rocks, however, both in europe and in north america, have yielded an abundant flora which resembles the existing vegetation of the globe in consisting mainly of angiospermous exogens and of monocotyledons.[ ] in europe the plant-remains in question have been found chiefly in certain sands in the neighbourhood of aix-la-chapelle, and they consist of numerous ferns, conifers (such as _cycadopteris_), screw pines (_pandanus_), oaks (_quercus_), walnut (_juglans_), fig (_ficus_), and many _proteaceoe_, some of which are referred to existing genera (_dryandra, banksia, grevillea_, &c.) [footnote : the "flowering plants" are divided into the two great groups of the endogens and exogens. the _endogens_ (such as grasses, palms, lilies, &c.) have no true bark, nor rings of growth, and the stem is said to be "endogenous;" the young plant also possesses but a single seed-leaf or "cotyledon." hence these plants are often simply called "_monocotyledons_." the _exogens_, on the other hand, have a true bark; and the stem increases by annual additions to the outside, so that rings of growth are produced. the young plant has two seed-leaves or "cotyledons," and these plants are therefore called "_dicotyledons_." amongst the exogens, the pines (_conifers_) and the cycads have seeds which are unprotected by a seed-vessel, and they are therefore called "_gymnosperms_." all the other exogens, including the ordinary trees, shrubs, and flowering plants, have the seeds enclosed in a seed-vessel, and are therefore called "_angiosperms_." the derivation of these terms will be found in the glossary at the end of the volume.] in north america, the cretaceous strata of new jersey, alabama, nebraska, kansas, &c., have yielded the remains of numerous plants, many of which belong to existing genera. amongst these may be mentioned tulip-trees (_liriodendron_), sassafras (fig. ), oaks (_quercus_), beeches (_fagus_), plane-trees (_platanus_), alders (_alnus_), dog-wood (_cornus_), willows (_salix_), poplars (_populus_), cypresses (_cupressus_), bald cypresses (_taxodium_), magnolias, &c. besides these, however, there occur other forms which have now entirely disappeared from north america--as, for example, species of _cinnamomum_ and _araucaria_. it follows from the above, that the lower and upper cretaceous rocks are, from a botanical point of view, sharply separated from one another. the palæozoic period, as we have seen, is characterised by the prevalance of "flowerless" plants (_cryptogams_), its higher vegetation consisting almost exclusively of conifers. the mesozoic period, as a whole, is characterised by the prevalence of the cryptogamic group of the ferns, and the gymnospermic groups of the conifers and the cycads. up to the close of the lower cretaceous, no angiospermous exogens are certainly known to have existed, and monocotyledonous plants or endogens are very poorly represented. with the upper cretaceous, however, a new era of plant-life, of which our present is but the culmination, commenced, with a great and apparently sudden development of new forms. in place of the ferns, cycads, and conifers of the earlier mesozoic deposits, we have now an astonishingly large number of true angiospermous exogens, many of them belonging to existing types; and along with these are various monocotyledonous plants, including the first examples of the great and important group of the palms. it is thus a matter of interest to reflect that plants closely related to those now inhabiting the earth, were in existence at a time when the ocean was tenanted by ammonites and belemnites, and when land and sea and air were peopled by the extraordinary extinct reptiles of the mesozoic period. [illustration: fig. .--cretaceous angiosperms. a. _sassafras cretaceum; b, liriodendron meekii; c, leguminosites marcouanus; d, salix meekii_. (after dana.)] as regards animal life, the _protozoans_ of the cretaceous period are exceedingly numerous, and are represented by _foraminifera_ and _sponges_. as we have already seen, the white chalk itself is a deep-sea deposit, almost entirely composed of the microscopic shells of _foraminifers_, along with sponge-spicules, and organic _débris_ of different kinds (see fig. ). the green grains which are so abundant in several minor subdivisions of the cretaceous, are also in many instances really casts in glauconite of the chambered shells of these minute organisms. a great many species of _foraminifera_ have been recognised in the chalk; but the three principal genera are _globigerina, rotalia_ (fig. ), and _textularia_--groups which are likewise characteristic of the "ooze" of the atlantic and pacific oceans at great depths. the flints of the chalk also commonly contain the shells of _foraminifera_. the upper greensand has yielded in considerable numbers the huge _foraminifera_ described by dr carpenter under the name of _parkeria_, the spherical shells of which are composed of sand-grains agglutinated together, and sometimes attain a diameter of two and a quarter inches. the cretaceous sponges are extremely numerous, and occur under a great number of varieties of shape and structure; but the two most characteristic genera are _siphonia_ and _ventriculites_, both of which are exclusively confined to strata of this age. the _siphonioe_ (fig. ) consist of a pear-shaped, sometimes lobed head, supported by a longer or shorter stern, which breaks up at its base into a number of root-like processes of attachment. the water gained access to the interior of the sponge by a number of minute openings covering the surface, and ultimately escaped by a single, large, chimney-shaped aperture at the summit. in some respects these sponges present a singular resemblance to the beautiful "vitreous sponges" (_holtenia_ or _pheronema_) of the deep atlantic; and, like these, they were probably denizens of a deep sea, the _ventriculites_ of the chalk (fig. ) is, however, a genus still more closely allied to the wonderful flinty sponges, which have been shown, by the researches of the porcupine, lightning, and challenger expeditions, to live half buried in the calcareous ooze of the abysses of our great oceans. many forms of this genus are known, having "usually the form of graceful vases, tubes, or funnels, variously ridged or grooved, or otherwise ornamented on the surface, frequently expanded above into a cup-like lip, and continued below into a bundle of fibrous roots. the minute structure of these bodies shows an extremely delicate tracery of fine tubes, sometimes empty, sometimes filled with loose calcareous matter dyed with peroxide of iron."--(sir wyville thomson.) many of the chalk sponges, originally calcareous, have been converted into flint subsequently; but the ventriculites are really composed of this substance, and are therefore genuine "siliceous sponges," like the existing venus's flower-basket (_euplectella_). like the latter, the skeleton was doubtless originally composed, in the young state, of disconnected six-rayed spicules, which ultimately become fixed together to constitute a continuous frame-work. the sea-water, as in the recent forms, must have been admitted to the interior of the sponge by numerous apertures on its exterior, subsequently escaping by a single large opening at its summit. [illustration: fig. --_kotalia boueana_.] [illustration: fig. .--_siphonia ficus. upper greensand. europe.] [illustration: fig. .--_ventriculites simplex_. white chalk. britain.] amongst the _coelenterates_, the "hydroid zoophytes" are represented by a species of the encrusting genus _hydractinia_, the horny polypary of which is so commonly found at the present day adhering to the exterior of shells. the occurrence of this genus is of interest, because it is the first known instance in the entire geological series of the occurrence of an unquestionable hydroid of a modern type, though many of the existing forms of these animals possess structures which are perfectly fitted for preservation in the fossil condition. the corals of the cretaceous series are not very numerous, and for the most part are referable to types such as _trochocyathus, stephanophyllia, parasmilia, synhelia_ (fig. ), &c., which belong to the same great group of corals as the majority of existing forms. we have also a few "tabulate corals" (_polytremacis_), hardly, if at all, generically separable from very ancient forms (_heliolites_); and the lower greensand has yielded the remains of the little _holocystis elegans_, long believed to be the last of the great palæozoic group of the _rugosa_. [illustration: fig. .--_synhelia sharpeana_. chalk, england.] as regards the _echinoderms_, the group of the _crinoids_ now exhibits a marked decrease in the number and variety of its types. the "stalked" forms are represented by _pentacrinus_ and _bourgueticrinus_, and the free forms by feather-stars like our existing _comatuloe_; whilst a link between the stalked and free groups is constituted by the curious "tortoise encrinite (_marsupites_). by far the most abundant cretaceous echinoderms, however, are sea-urchins (_echinoids_); though several star-fishes are known as well. the remains of sea-urchins are so abundant in various parts of the cretaceous series, especially in the white chalk, and are often so beautifully preserved, that they constitute one of the most marked features of the fauna of the period. from the many genera of sea-urchins which occur in strata of this age, it is difficult to select characteristic types; but the genera _galerites_ (fig. ), _discoidea_ (fig. ), _micraster, ananchytes, diadema, salenia_, and _cidaris_, may be mentioned as being all important cretaceous groups. coming to the _annulose animals_ of the cretaceous period, there is little special to remark. the _crustaceans_ belong for the most part to the highly-organised groups of the lobsters and the crabs (the macrurous and brachyurous decapods); but there are also numerous little _ostracodes_, especially in the fresh-water strata of the wealden. it should further be noted that there occurs here a great development of the singular _crustaceous_ family of the barnacles (_lepadidoe_), whilst the allied family of the equally singular acorn-shells (_balanidoe_) is feebly represented as well. [illustration: fig. .--_galerites albogalerus_, viewed from below, from the side, and from above. white chalk.] [illustration: fig. .--_discoidea cylindrica_; under, side, and upper aspect. upper greensand.] passing on to the _mollusca_, the class of the sea-mats and sea-mosses (_polyzoa_) is immensely developed in the cretaceous period, nearly two hundred species being known to occur in the chalk. most of the cretaceous forms belong to the family of the _escharidoe_, the genera _eschara_ and _escharina_ (fig. ) being particularly well represented. most of the cretaceous _polyzoans_ are of small size, but some attain considerable dimensions, and many simulate corals in their general form and appearance. the lamp-shells (_brachiopods_) have now reached a further stage of the progressive decline, which they have been undergoing ever since the close of the palæozoic period. though individually not rare, especially in certain minor subdivisions of the series, the number of generic types has now become distinctly diminished, the principal forms belonging to the genera _terebratula, terebratella_ (fig. ), _terebratulina, rhynchonella_, and _crania_ (fig. ). in the last mentioned of these, the shell is attached to foreign bodies by the substance of one of the valves (the ventral), whilst the other or free valve is more or less limpet-shaped. all the above-mentioned genera are in existence at the present day; and one _species_--namely, _terebratulina striata_--appears to be undistinguishable from one now living--the _terebratulina caputserpentis_. [illustration: fig. .--a small fragment of _escharina oceani_, of the natural size; and a portion of the same enlarged. upper greensand.] [illustration: fig. .--_terebratella astieriana_. gault.] whilst the lamp-shells are slowly declining, the bivalves (_limellibranchs_) are greatly developed, and are amongst the most abundant and characteristic fossils of the cretaceous period. in the great river-deposit of the wealden, the bivalves are forms proper to fresh water, belonging to the existing river-mussels (_unio_), _cyrena_ and _cyclas_; but most of the cretaceous lamellibranchs are marine. some of the most abundant and characteristic of these belong to the great family of the oysters (_ostreidoe_). amongst these are the genera _gryphtoea_ and _exogyra_, both of which we have seen to occur abundantly in the jurassic; and there are also numerous true oysters (_ostrea_, fig. ) and thorny oysters (_spondylus_, fig. ). the genus _trigonia_, so characteristic of the mesozoic deposits in general, is likewise well represented in the cretaceous strata. no single genus of bivalves is, however, so highly characteristic of the cretaceous period as _inoceramus_, a group belonging to the family of the pearl-mussels (_aviculidoe_). the shells of this genus (fig. ) have the valves unequal in size, the larger valve often being much twisted, and both valves being marked with radiating ribs or concentric furrows. the hinge-line is long and straight, with numerous pits for the attachment of the ligament which serves to open the shell. some of the _inocerami_ attain a length of two or three feet, and fragments of the shell are often found perforated by boring sponges. another extraordinary family of bivalves, which is exclusively confined to the cretaceous rocks, is that of the _hippuritidoe_. all the members of this group (fig. ) were attached to foreign objects, and lived associated in beds, like oysters. the two valves of the shell are always altogether unlike in sculpturing, appearance, shape, and size; and the cast of the interior of the shell is often extremely unlike the form of the outer surface. the type-genus of the family is _hippurites_ itself (fig. ), in which the shell is in the shape of a straight or slightly-twisted horn, sometimes a foot or more in length, constituted by the attached lower valve, and closed above by a small lid-like free upper valve. about a hundred species of the family of the _hippuritidoe_ are known, all of these being cretaceous, and occurring in britain (one species only), in southern europe, the west indies, north america, algeria, and egypt. species of this family occur in such numbers in certain compact marbles in the south of europe, of the age of the upper cretaceous (lower chalk), as to have given origin to the name of "hippurite limestones," applied to these strata. [illustration: fig. .--_crania ignabergensis_. the left-hand figure shows the perfect shell, attached by its ventral valve to a foreign body; the middle figure shows the exterior of the limpet-shaped dorsal valve; and the right-hand figure represents the interior of the attached valve. white chalk.] [illustration: fig. .--_ostrea couloni_. lower greensand.] [illustration: fig. .--_spondylus spinosus_. white chalk.] [illustration: fig. .--_inoceramus sulcatus_. gault.] the univalves (_gasteropods_) of the cretaceous period are not very numerous, nor particularly remarkable. along with species of the persistent genus _pleurotomaria_ and the mesozoic _nerinoea_, we meet with examples of such modern types as _turritella_ and _natica_, the staircase-shells (_solarium_), the wentle-traps (_scalaria_), the carrier-shells (_phorus_), &c. towards the close of the cretaceous period, and especially in such transitional strata as the maestricht beds, the faxöe limestone, and the pisolitic limestone of france, we meet with a number of carnivorous ("siphonostomatous") univalves, in which the mouth of the shell is notched or produced into a canal. amongst these it is interesting to recognise examples of such existing genera as the volutes (_voluta_, fig. ), the cowries (_cyproea_), the mitre-shells (_mitra_), the wing - shells (_strombus_), the scorpion-shells (_pteroceras_), &c. [illustration: fig. .--_hippurites toucasiana_. a large individual, with two smaller ones attached to it. upper cretaceous, south of europe.] [illustration: fig. .--_voluta elongata_. white chalk.] upon the whole, the most characteristic of all the cretaceous molluscs are the _cephalopods_, represented by the remains of both _tetrabranchiate_ and _dibranchiate_ forms. amongst the former, the long-lived genus _nautilus_ (fig. ) again reappears, with its involute shell, its capacious body-chamber, its simple septa between the air-chambers, and its nearly or quite central siphuncle. the majority of the chambered _cephalopods_ of the cretaceous belong, however, to the complex and beautiful family of the _ammonitidoe_, with their elaborately folded and lobed septa and dorsally-placed siphuncle. this family disappears wholly at the close of the cretaceous period; but its approaching extinction, so far from being signalised by any slow decrease and diminution in the number of specific or generic types, seems to have been attended by the development of whole series of new forms. the genus _ammonites_ itself, dating from the carboniferous, has certainly passed its prime, but it is still represented by many species, and some of these attained enormous dimensions (two or three feet in diameter). the genus _ancyloceras_ (fig. ), though likewise of more ancient origin (jurassic), is nevertheless very characteristic of the cretaceous. in this genus the first portion of the shell is in the form of a flat spiral, the coils of which are not in contact; and its last portion is produced at a tangent, becoming ultimately bent back in the form of a crosier. besides these pre-existent types, the cretaceous rocks have yielded a great number of entirely new forms of the _ammonitidoe_, which are not known in any deposits of earlier or later date. amongst the more important of these may be mentioned _crioceras, turrilites, scaphites, hamites, ptychoceras_, and _baulites_. in the genus _crioceras_ (fig. , d), the shell consists of an open spiral, the volutions of which are not in contact, thus resembling a partially-unrolled _ammonite_ or the inner portion of an _ancyloceras_. in _turrilites_ (fig. ), the shell is precisely like that of the _ammonite_ in its structure; but instead of forming a flat spiral, it is coiled into an elevated turreted shell, the whorls of which are in contact with one another. in the genus _scaphites_ (fig. , e), the shell resembles that of _ancyloceras_ in consisting of a series of volutions coiled into a flat spiral, the last being detached from the others, produced, and ultimately bent back in the form of a crosier; but the whorls of the enrolled part of the shell are in contact, instead of being separate as in the latter. in the genus _hamites_ (fig. , f), the shell is an extremely elongated cone, which is bent upon itself more than once, in a hook-like manner, all the volutions being separate. the genus _ptychoteras_ (fig. , a) is very like _hamites_, except that the shell is only bent once; and the two portions thus bent are in contact with one another. lastly, in the genus _baculites_ (fig. , b and c) the shell is simply a straight elongated cone, not bent in any way, but possessing the folded septa which characterise the whole ammonite family. the _baculite_ is the simplest of all the forms of the _ammonitidoe_; and all the other forms, however complex, may be regarded as being simply produced by the bending or folding of such a conical septate shell in different ways. the _baculite_, therefore, corresponds, in the series of the _ammonitidoe_, to the _orthoceras_ in the series of the _nautilidoe_. all the above-mentioned genera are characteristically, or exclusively, cretaceous, and they are accompanied by a number of other allied forms, which cannot be noticed here. not a single one of these genera, further, has hitherto been detected in any strata higher than the cretaceous. we may therefore consider that these wonderful, varied, and elaborate forms of _ammonitidoe_ constitute one of the most conspicuous features in the life of the chalk period. [illustration: fig. .--different views of _nautilus danicus_. faxöe limestone (upper cretaceous), denmark.] [illustration: fig. .--_ancyloceras matheronianus_. gault.] the _dibranchiate cephalopods_ are represented partly by the beak-like jaws of unknown species of cuttle-fishes and partly by the internal skeletons of belemnites. amongst the latter, the genus _belemnites_ itself holds its place in the lower part of the cretaceous series; but it disappears in the upper portion of the series, and its place is taken by the nearly-allied genus _belemnitella_ (fig. ), distinguished by the possession of a straight fissure in the upper end of the guard. this also disappears at the close of the cretaceous period; and no member of the great mesozoic family of the _belemnitidoe_ has hitherto been discovered in any tertiary deposit, or is known to exist at the present day. [illustration: fig. .--_turrilites catenatus_. the lower figure represents the entire shell; the upper figure represents the base of the shell seen from below. gault.] [illustration: fig. .--a, _ptychoceras emericianum_, reduced--lower greensand; b, _baculites anceps_, reduced--chalk; c, portion of the same, showing the folded edges of the septa; d, _crioceras cristatum_, reduced--gault; e, _scaphites oequalis_, natural size--chalk; f, _hamites rotundus_, restored--gault.] passing on next to the _vertebrate animals_ of the cretaceous period, we find the _fishes_ represented as before by the ganoids and the placoids, to which, however, we can now add the first known examples of the great group of the _bony fishes_ or _teleosteans_, comprising the great majority of existing forms. the _ganoid_ fishes of the cretaceous (_lepidotus, pycnodus_, &c.) present no features of special interest. little, also, need be said about the _placoid_ fishes of this period. as in the jurassic deposits, the remains of these consist partly of the teeth of genuine sharks (_lamna, odontaspis_, &c.) and partly of the teeth and defensive spines of cestracionts, such as the living port-jackson shark. the pointed and sharp-edged teeth of true sharks are very abundant in some beds, such as the upper greensand, and are beautifully preserved. the teeth of some forms (_carcharias_, &c.) attain occasionally a length of three or four inches, and indicate the existence in the cretaceous seas of huge predaceous fishes, probably larger than any existing sharks. the remains of _cestracionts_ consist partly of the flattened teeth of genera such as _acrodus_ and _ptychodus_ (the latter confined to rocks of this age), and partly of the pointed teeth of _hybodus_, a genus which dates from the trias. in this genus the teeth (fig. ) consist of a principal central cone, flanked by minor lateral cones; and the fin-spines (fig. ) are longitudinally grooved, and carry a series of small spines on their hinder or concave margin. lastly, the great modern order of the bony fishes or _teleosteans_ makes its first appearance in the upper cretaceous rocks, where it is represented by forms belonging to no less than three existing groups--namely, the salmon family (_salmonidoe_), the herring family (_clupeidoe_), and the perch family (_percidoe_). all these fishes have thin, horny, overlapping scales, symmetrical ("homocercal") tails, and bony skeletons. the genus _beryx_ (fig. , ) is one represented by existing species at the present day, and belongs to the perch family. the genus _osmeroides_, again (fig. , ), is supposed to be related to the living smelts (_osmerus_), and, therefore, to belong to the salmon tribe. [illustration: fig. .--guard of _belemnitella mucronata_. white chalk.] [illustration: fig. .--tooth of _hybodus_.] [illustration: fig. .--fin-spine of _hybodus_. lower greensand.] [illustration: fig. .-- , _beryx lewesiensis_, a percoid fish from the chalk; , _osmeroides mantelli_, a salmonoid fish from the chalk.] no remains of _amphibians_ have hitherto been detected in any part of the cretaceous series; but _reptiles_ are extremely numerous, and belong to very varied types. as regards the great extinct groups of reptiles which characterise the mesozoic period as a whole, the huge "enaliosaurs" or "sea-lizards" are still represented by the _ichthyosaur_ and the _plesiosaur_. nearly allied to the latter of these is the _elasmosaurus_ of the american cretaceous, which combined the long tail of the ichthyosaur with the long neck of the plesiosaur. the length of this monstrous reptile could not have been less than fifty feet, the neck consisting of over sixty vertebræ and measuring over twenty feet in length. the extraordinary flying reptiles of the jurassic are likewise well represented in the cretaceous rocks by species of the genus _pterodactylus_ itself, and these later forms are much more gigantic in their dimensions than their predecessors. thus some of the cretaceous pterosaurs seem to have had a spread of wing of from twenty to twenty-five feet, more than realising the "dragons" of fable in point of size. the most remarkable, however, of the cretaceous _pterosaurs_ are the forms which have recently been described by professor marsh under the generic title of _pteranodon_. in these singular forms--so far only known as american--the animal possessed a skeleton in all respects similar to that of the typical pterodactyles, except that the jaws are completely destitute of teeth. there is, therefore, the strongest probability that the jaws were encased in a horny sheath, thus coming to resemble the beak of a bird. some of the recognised species of _pteranodon_ are very small; but the skull of one species (_p. longiceps_) is not less than a yard in length, and there are portions of the skull of another species which would indicate a length of four feet for the cranium. these measurements would point to dimensions larger than those of any other known pterosaurs. the great mesozoic order of the _deinosaurs_ is largely represented in the cretaceous rocks, partly by genera which previously existed in the jurassic period, and partly by entirely new types. the great delta-deposit of the wealden, in the old world, has yielded the remains of various of these huge terrestrial reptiles, and very many others have been found in the cretaceous deposits of north america. one of the most celebrated of the cretaceous deinosaurs is the _iguanodon_, so called from the curious resemblance of its teeth to those of the existing but comparatively diminutive _iguana_. the teeth (fig. ) are soldered to the inner face of the jaw, instead of being sunk in distinct sockets; and they have the form of somewhat flattened prisms, longitudinally ridged on the outer surface, with an obtusely triangular crown, and having the enamel crenated on one or both sides. they present the extraordinary feature that the crowns became worn down flat by mastication, showing that the _iguanodon_ employed its teeth in actually chewing and triturating the vegetable matter on which it fed. there can therefore be no doubt but that the _iguanodon_, in spite of its immense bulk, was an herbivorous reptile, and lived principally on the foliage of the cretaceous forests amongst which it dwelt. its size has been variously estimated at from thirty to fifty feet, the thigh-bone in large examples measuring nearly five feet in length, with a circumference of twenty-two inches in its smallest part. with the strong and massive hind-limbs are associated comparatively weak and small fore-limbs; and there seems little reason to doubt that the _iguanodon_ must have walked temporarily or permanently upon its hind-limbs, after the manner of a bird. this conjecture is further supported by the occurrence in the strata which contain the bones of the _iguanodon_ of gigantic three-toed foot-prints, disposed _singly_ in a double track. these prints have undoubtedly been produced by some animal walking on two legs; and they can hardly, with any probability, be ascribed to any other than this enormous reptile. closely allied to the _iguanodon_ is the _hadrosaurus_ of the american cretaceous, the length of which is estimated at twenty-eight feet. _iguanodon_ does not appear to have possessed any integumentary skeleton; but the great _hyloeosaurus_ of the wealden seems to have been furnished with a longitudinal crest of large spines running down the back, similar to that which is found in the comparatively small iguanas of the present day. the _megalosaurus_ of the oolites continued to exist in the cretaceous period; and, as we have previously seen, it was carnivorous in its habits. the american _loelaps_ was also carnivorous, and, like the megalosaur, which it very closely resembles, appears to have walked upon its hind-legs, the fore-limbs being disproportionately small. [illustration: fig. .--teeth of iguanodon mantellii. wealden, britain.] another remarkable group of reptiles, exclusively confined to the cretaceous series, is that of the _mosasauroids_, so called from the type-genus _mosasaurus_. the first species of _mosasaurus_ known to science was the _m. camperi_ (fig. ), the skull of which--six feet in length--was discovered in in the maestricht chalk at maestricht. as this town stands on the river meuse, the name of _mosasaurus_ ("lizard of the meuse") was applied to this immense reptile. of late years the remains of a large number of reptiles more or less closely related to _mosasaurus_, or absolutely belonging to it, have been discovered in the cretaceous deposits of north america, and have been described by professors cope and marsh. all the known forms of this group appear to have been of large size--one of them, _mosasaurus princeps_, attaining the length of seventy-five or eighty feet, and thus rivalling the largest of existing whales in its dimensions. the teeth in the "mosasauroids" are long, pointed, and slightly curved; and instead of being sunk in distinct sockets, they are firmly amalgamated with the jaws, as in modern lizards. the palate also carried teeth, and the lower jaw was so constructed as to allow of the mouth being opened to an immense width, somewhat as in the living serpents. the body was long and snake-like, with a very long tail, which is laterally compressed, and must have served as a powerful swimming-apparatus. in addition to this, both pairs of limbs have the bones connecting them with the trunk greatly shortened; whilst the digits were enclosed in the integuments, and constituted paddles, closely resembling in structure the "flippers" of whales and dolphins. the neck is sometimes moderately long, but oftener very short, as the great size and weight of the head would have led one to anticipate. bony plates seem in some species to have formed an at any rate partial covering to the skin; but it is not certain that these integumentary appendages were present in all. upon the whole, there can be no doubt but that the mosasauroid reptiles--the true "sea-serpents" of the cretaceous period--were essentially aquatic in their habits, frequenting the sea, and only occasionally coming to the land. [illustration: fig. .--skull of _mosasaurus camperi_, greatly reduced. maestricht chalk.] the "mosasauroids" have generally been regarded as a greatly modified group of the lizards (_lacertilia_). whether this reference be correct or not--and recent investigations render it dubious--the cretaceous rocks have yielded the remains of small lizards not widely removed from existing forms. the recent order of the _chelonians_ is also represented in the cretaceous rocks, by forms closely resembling living types. thus the fresh-water deposits of the wealden have yielded examples of the "terrapins" or "mud-turtles" (_emys_); and the marine cretaceous strata have been found to contain the remains of various species of turtles, one of which is here figured (fig. ). no true serpents (_ophidia_) have as yet been detected in the cretaceous rocks; and this order does not appear to have come into existence till the tertiary period. lastly, true crocodiles are known to have existed in considerable numbers in the cretaceous period. the oldest of these occur in the fresh-water deposit of the wealden; and they differ from the existing forms of the group in the fact that the bodies of the vertebræ, like those of the jurassic crocodiles, are bi-concave, or hollowed out at both ends. in the greensand of north america, however, occur the remains of crocodiles which agree with all the living species in having the bodies of the vertebræ in the region of the back hollowed out in front and convex behind. [illustration: fig. .--carapace of _chelone benstedi_. lower chalk. (after owen.)] _birds_ have not hitherto been shown, with certainty, to have existed in europe during the cretaceous period, except in a few instances in which fragmentary remains belonging to this class have been discovered. the cretaceous deposits of north america have, however, been shown by professor marsh to contain a considerable number of the remains of birds, often in a state of excellent preservation. some of these belong to swimming or wading birds, differing in no point of special interest from modern birds of similar habits. others, however, exhibit such extraordinary peculiarities that they merit more than a passing notice. one of the forms in question constitutes the genus _ichthyornis_ of marsh, the type-species of which (_i. dispar_) was about as large as a pigeon. in two remarkable respects, this singular bird differs from all known living members of the class. one of these respects concerns the jaws, both of which exhibit the reptilian character of being armed with numerous small pointed _teeth_ (fig. , a), sunk in distinct sockets. no existing bird possesses teeth; and this character forcibly recalls the bird-like pterosaurs, with their toothed jaws. _ichthyornis_, however, possessed fore-limbs constructed strictly on the type of the "wing" of the living birds; and it cannot, therefore, be separated from this class. another extraordinary peculiarity of _ichthyornis_ is, that the bodies of the _vertebrie_ (fig. , c) were _bi-concave_, as is the case with many extinct reptiles and almost all fishes, but as does not occur in any living bird. there can be little doubt that _ichthyornis_ was aquatic in its habits, and that it lived principally upon fishes; but its powerful wings at the same time indicate that it was capable of prolonged flight. the tail of _ichthyornis_ has, unfortunately, not been discovered; and it is at present impossible to say whether this resembled the tail of existing birds, or whether it was elongated and composed of separate vertebræ, as in the jurassic _archoeopteryx_. still more wonderful than _ichthyornis_ is the marvellous bird described by marsh under the name of _hesperornis regalis_. this presents us with a gigantic diving bird, somewhat resembling the existing "loons" (_colymbus_), but agreeing with _ichthyornis_ in having the jaws furnished with conical, recurved, pointed teeth (fig. , b). hence these forms are grouped together in a new sub-class, under the name of _odontornithes_ or "toothed birds." the teeth of _hesperornis_ (fig. , d) resemble those of _ichthyornis_ in their general form; but instead of being sunk in distinct sockets, they are simply implanted in a deep continuous groove in the bony substance of the jaw. the front of the upper jaw does not carry teeth, and was probably encased in a horny beak. the breast-bone is entirely destitute of a central ridge or keel, and the wings are minute and quite rudimentary; so that _hesperornis_, unlike _ichthyornis_, must have been wholly deprived of the power of flight, in this respect approaching the existing penguins. the tail consists of about twelve vertebræ, of which the last three or four are amalgamated to form a flat terminal mass, there being at the same time clear indications that the tail was capable of up and down movement in a vertical plane, this probably fitting it to serve as a swimming-paddle or rudder. the legs were powerfully constructed, and the feet were adapted to assist the bird in rapid motion through the water. the known remains of _hesperornis regalis_ prove it to have been a swimming and diving bird, of larger dimensions than any of the aquatic members of the class of birds with which we are acquainted at the present day. it appears to have stood between five and six feet high, and its inability to fly is fully compensated for by the numerous adaptations of its structure to a watery life. its teeth prove it to have been carnivorous in its habits, and it probably lived upon fishes. it is a curious fact that two birds agreeing with one another in the wholly abnormal character of possessing teeth, and in other respects so entirely different, should, like _ichthyornis_ and _hesperornis_, have lived not only in the same geological period, but also in the same geographical area; and it is equally curious that the area inhabited by these toothed birds should at the same time have been tenanted by winged and bird-like reptiles belonging to the toothed genus _pterodactylus_ and the toothless genus _pteranodon_. [illustration: fig. .--toothed birds (_odontornithes_) of the cretaceous rocks of america. a. left lower jaw of _ichthyornis dispar_, slightly enlarged; b, left lower jaw of _hesperornis regalis_, reduced to nearly one-fourth of the natural size; c. cervical vertebra of _ichthyornis dispar_, front view, twice the natural size; c', side view of the same; d, tooth of _hesperornis regalis_, enlarged to twice the natural size. (after marsh.)] no remains of _mammals_, finally, have as yet been detected in any sedimentary accumulations of cretaceous age. literature. the following list comprises some of the more important works and memoirs which may be consulted with reference to the cretaceous strata and their fossil contents:-- ( ) 'memoirs of the geological survey of great britain.' ( ) 'geology of england and wales.' conybeare and phillips. ( ) 'geology of yorkshire,' vol. ii. phillips. ( ) 'geology of oxford and the thames valley.' phillips. ( ) 'geological excursions through the isle of wight.' mantell. ( ) 'geology of sussex.' mantell. ( ) 'report on londonderry,' &c. portlock. ( ) 'recherches sur le terrain crétacé supérieur de l'angleterre et de l'irlande.' barrois. ( ) "geological survey of canada"--'report of progress, - .' ( ) 'geological survey of california.' whitney. ( ) 'geological survey of montana, idaho, wyoming, and utah.' hayden and meek. ( ) 'report on geology,' &c. (british north american boundary commission). g. m. dawson. ( ) 'manual of geology.' dana. ( ) 'lethæa rossica.' eichwald. ( ) 'petrefacta germaniæ.' goldfuss. ( ) 'fossils of the south downs.' mantell. ( ) 'medals of creation.' mantell. ( ) 'mineral conchology.' sowerby. ( ) 'lethæa geognostica.' bronn. ( ) 'malacostracous crustacea of the british cretaceous formation' (palæontographical society). bell. ( ) 'brachiopoda of the cretaceous formation' (palæontographical society). davidson. ( ) 'corals of the cretaceous formation' (palæontographical society). milne-edwards and haime. ( ) 'supplement to the fossil corals' (palæontographical society). martin duncan. ( ) 'echinodermata or the cretaceous formation' (palæontographical society). wright. ( ) 'monograph of the belemnitidæ' (palæontographical society). phillips. ( ) 'monograph of the trigoniæ' (palæontographical society). lycett. ( ) 'fossil cirripedes' (palæontographical society). darwin. ( ) 'fossil mollusca of the chalk of britain' (palæontographical society). sharpe. ( ) 'entomostraca of the cretaceous formation' (palæontographical society). rupert jones. ( ) 'monograph of the fossil reptiles of the cretaceous formation' (palæontographical society). owen. ( ) 'manual of palæontology.' owen. ( ) 'synopsis of extinct batrachia and reptilia.' cope. ( ) "structure of the skull and limbs in mosasauroid reptiles"--'american journ. sci. and arts, .' marsh. ( ) "on odontornithes"--'american journ. sci. and arts, .' marsh. ( ) 'ossemens fossiles.' cuvier. ( ) 'catalogue of ornithosauria.' seeley. ( ) 'paléontologie française.' d'orbigny. ( ) 'synopsis des echinides fossiles.' desor. ( ) 'cat. raisonné des echinides.' agassiz and desor. ( ) "echinoids"--'decades of the geol. survey of britain.' e. forbes. ( ) 'paléontologie française.' cotteau. ( ) 'versteinerungen der böhmischen kreide-formation.' reuss. ( ) "cephalopoda, gasteropoda, pelecypoda, brachiopoda; &c., of the cretaceous rocks of india"--'palæontologica indica,' ser. i., iii., v., vi., viii. stoliczka. ( ) "cretaceous reptiles of the united states"--'smithsonian contributions to knowledge,' vol. xiv. leidy. ( ) 'invertebrate cretaceous, and tertiary fossils of the upper missouri country,' . meek. chapter xviii. the eocene period. before commencing the study of the subdivisions of the kainozoic series, there are some general considerations to be noted. in the first place, there is in the old world a complete and entire physical break between the rocks of the mesozoic and kainozoic periods. in no instance in europe are tertiary strata to be found resting conformably upon any secondary rock. the chalk has invariably suffered much erosion and denudation before the lowest tertiary strata were deposited upon it. this is shown by the fact that the actually eroded surface of the chalk can often be seen; or, failing this, that we can point to the presence of the chalk-flints in the tertiary strata. this last, of course, affords unquestionable proof that the chalk must have been subjected to enormous denudation prior to the formation of the tertiary beds, all the chalk itself having been removed, and nothing left but the flints, while these are all rolled and rounded. in the continent of north america, on the other hand, the lowest tertiary strata have been shown to graduate downwards conformably with the highest cretaceous beds, it being a matter of difficulty to draw a precise line of demarcation between the two formations. in the second place, there is a marked break in the _life_ of the mesozoic and kainozoic periods. with the exception of a few _foraminifera_, and one _brachiopod_ (the latter doubtful), no cretaceous species is known to have survived the cretaceous period; while several characteristic _families_, such as the _ammonitidoe, belemnitidoe_, and _hippuritidoe_, died out entirely with the close of the cretaceous rocks. in the tertiary rocks, on the other hand, not only are all the animals and plants more or less like existing types, but we meet with a constantly-increasing number of _living species_ as we pass from the bottom of the kainozoic series to the top. upon this last fact is founded the modern classification of the kainozoic rocks, propounded by sil charles lyell. the absence in strata of tertiary age of the chambered cephalopods, the belemnites, the _hippurites_, the _inocerami_, and the diversified types of reptiles which form such conspicuous features in the cretaceous fauna, render the palæontological break between the chalk and the eocene one far too serious to be overlooked. at the same time, it is to be remembered that the evidence afforded by the explorations carried out of late years as to the animal life of the deep sea, renders it certain that the extinction of marine forms of life at the close of the cretaceous period was far less extensive than had been previously assumed. it is tolerably certain, in fact, that we may look upon some of the inhabitants of the depths of our existing oceans as the direct, if modified, descendants of animals which were in existence when the chalk was deposited. it follows from the general want of conformity between the cretaceous and tertiary rocks, and still more from the great difference in life, that the cretaceous and tertiary periods are separated, in the old world at any rate, by an enormous lapse of unrepresented time. how long this interval may have been, we have no means of judging exactly, but it very possibly was as long as the whole kainozoic epoch itself. some day we shall doubtless find, at some part of the earth's surface, marine strata which were deposited during this period, and which will contain fossils intermediate in character between the organic remains which respectively characterise the secondary and tertiary periods. at present, we have only slight traces of such deposits--as, for instance, the maestricht beds, the faxöe limestone, and the pisolitic limestone of france. classification of the tertiary rocks.--the classification of the tertiary rocks is a matter of unusual difficulty, in consequence of their occurring in disconnected basins, forming a series of detached areas, which hold no relations of superposition to one another. the order, therefore, of the tertiaries in point of time, can only be determined by an appeal to fossils; and in such determination sir charles lyell proposed to take as the basis of classification the _proportion of living or existing species of mollusca which occurs in each stratum or group of strata_. acting upon this principle, sir charles lyell divides the tertiary series into four groups:-- i. the _eocene_ formation (gr. _eos_, dawn; _kainos_, new), containing the smallest proportion of existing species, and being, therefore, the oldest division. in this classification, only the _mollusca_ are taken into account; and it was found that of these about three and a half per cent were identical with existing species. ii. the _miocene_ formation (gr. _meion_, less; _kainos_, new), with more recent species than the eocene, but _less_ than the succeeding formation, and less than one-half the total number in the formation. as before, only the _mollusca_ are taken into account, and about per cent of these agree with existing species. iii. the _pliocene_ formation (gr. _pleion_, more; _kainos_, new), with generally _more_ than half the species of shells identical with existing species--the proportion of these varying from to per cent in the lower beds of this division, up to or per cent in its higher portion. iv. the _post-tertiary formations_, in which all _the shells belong to existing species_. this, in turn, is divided into two minor groups--the _post-pliocene_ and _recent formations_. in the _post-pliocene_ formations, while all the _mollusca_ belong to existing species, most of the _mammals_ belong to extinct species. in the recent period, the quadrupeds, as well as the shells, belong to living species. the above, with some modifications, was the original classification proposed by sir charles lyell for the tertiary rocks, and now universally accepted. more recent researches, it is true, have somewhat altered the proportions of existing species to extinct, as stated above. the general principle, however, of an increase in the number of living species, still holds good; and this is as yet the only satisfactory basis upon which it has been proposed to arrange the tertiary deposits. eocene formation. the eocene rocks are the lowest of the tertiary series, and comprise all those tertiary deposits in which there is only a small proportion of existing _mollusca_--from three and a half to five per cent. the eocene rocks occur in several basins in britain, france, the netherlands, and other parts of europe, and in the united states. the subdivisions which have been established are extremely numerous, and it is often impossible to parallel those of one basin with those of another. it will be sufficient, therefore, to accept the division of the eocene formation into three great groups--lower, middle, and upper eocene--and to consider some of the more important beds comprised under these heads in europe and in north america. i. eocene of britain. ( .) lower eocene.--the base of the eocene series in britain is constituted by about feet of light-coloured, sometimes argillaceous sands (_thanet sands_), which are of marine origin. above these, or forming the base of the formation where these are wanting, come mottled clays and sands with lignite (_woolwich and reading series_), which are estuarine or fluvio-marine in origin. the highest member of the lower eocene of britain is the "london clay," consisting of a great mass of dark-brown or blue clay, sometimes with sandy beds, or with layers of "septaria," the whole attaining a thickness of from to as much as feet. the london clay is a purely marine deposit, containing many marine fossils, with the remains of terrestrial animals and plants; all of which indicate a high temperature of the sea and tropical or sub-tropical conditions of the land. ( .) middle eocene.--the inferior portion of the middle eocene of britain consists of marine beds, chiefly consisting of sand, clays, and gravels, and attaining a very considerable thickness (_bag-shot and bracklesham beds_). the superior portion of the middle eocene of britain, on the other hand, consists of deposits which are almost exclusively fresh-water or brackish-water in origin (_headon and osborne series_). the chief continental formations of middle eocene age are the "calcaire grossier" of the paris basin, and the "nummulitic limestone" of the alps. ( .) upper eocene.--if the headon and osborne beds of the isle of wight be placed in the middle eocene, the only british representatives of the upper eocene are the _bembridge beds_. these strata consist of limestones, clays, and marls, which have for the most part been deposited in fresh or brackish water. ii. eocene beds of the paris basin.--the eocene strata are very well developed in the neighbourhood of paris, where they occupy a large area or basin scooped out of the chalk. the beds of this area are partly marine, partly freshwater in origin; and the following table (after sir charles lyell) shows their subdivisions and their parallelism with the english series:-- general table of french eocene strata. upper eocene. _french subdivisions._ _english equivalents._ a. . gypseous series of mont . bembridge series. montmartre. a. . calcaire silicieux, or . osborne and headon series. travertin inférieur. a. . grès de beauchamp, or . white sand and clay of sables moyens. barton cliff, hants. middle eocene. b. . calcaire grossier. . bagshot and bracklesham beds. b. . soissonnais sands, or . wanting. lits coquilliers. lower eocene. c. . argile de londres at base . london clay. of hill of cassel, near dunkirk. c. . argile plastique and . plastic clay and sand with lignite. lignite (woolwich and reading series). c. . stables de bracheux. . thanet sands. iii. eocene strata of the united states.--the lowest member of the eocene deposits of north america is the so-called "_lignitic formation_," which is largely developed in mississippi, tennessee, arkansas, wyoming, utah, colorado, and california, and sometimes attains a thickness of several thousand feet. stratigraphically, this formation exhibits the interesting point that it graduates downwards insensibly and conformably into the cretaceous, whilst it is succeeded _uncomformably_ by strata of middle eocene age. lithologically, the series consists principally of sands and clays, with beds of lignite and coal, and its organic remains show that it is principally of fresh-water origin with a partial intermixture of marine beds. these marine strata of the "lignitic formation" are of special interest, as showing such a commingling of cretaceous and tertiary types of life, that it is impossible to draw any rigid line in this region between the mesozoic and kainozoic systems. thus the marine beds of the lignitic series contain such characteristic cretaceous forms as _inoceramus_ and _ammonites_, along with a great number of univalves of a distinctly tertiary type (cones, cowries, &c.) upon the whole, therefore, we must regard this series of deposits as affording a kind of transition between the cretaceous and the eocene, holding in some respects a position which may be compared with that held by the purbeck beds in britain as regards the jurassic and cretaceous. the middle eocene of the united states is represented by the _claiborne_ and _jackson_ beds. the _claiborne series_ is extensively developed at claiborne, alabama, and consists of sands, clays, lignites, marls, and impure limestones, containing marine fossils along with numerous plant-remains. the _jackson series_ is represented by lignitic clays and marls which occur at jackson, mississippi. amongst the more remarkable fossils of this series are the teeth and bones of cetaceans of the genus _zeuglodon_. strata of upper eocene age occur in north america at vicksburg, mississippi, and are known as the _vicksburg series_. they consist of lignites, clays, marls, and limestones. freshwater deposits of eocene age are also largely developed in parts of the rocky mountain region. the most remarkable fossils of these beds are mammals, of which a large number of species have been already determined. life of the eocene period. the fossils of the eocene deposits are so numerous that nothing more can be attempted here than to give a brief and general sketch of the life of the period, special attention being directed to some of the more prominent and interesting types, amongst which--as throughout the tertiary series--the mammals hold the first place. it is not uncommon, indeed, to speak of the tertiary period as a whole under the name of the "age of mammals," a title at least as well deserved as that of "age of reptiles" applied to the mesozoic, or "age of molluscs" applied to the palæozoic epoch. as regards the _plants_ of the eocene, the chief point to be noticed is, that the conditions which had already set in with the commencement of the upper cretaceous, are here continued, and still further enforced. the _cycads_ of the secondary period, if they have not totally disappeared, are exceedingly rare; and the _conifers_, losing the predominance which they enjoyed in the mesozoic, are now relegated to a subordinate though well-defined place in the terrestrial vegetation. the great majority of the eocene plants are referable to the groups of the angiospermous exogens and the monocotyledons; and the vegetation of the period, upon the whole, approximates closely to that now existing upon the earth. the plants of the european eocene are, however, in the main most closely allied to forms which are now characteristic of tropical or sub-tropical regions. thus, in the london clay are found numerous fruits of palms (_napdites_, fig. ), along with various other plants, most of which indicate a warm climate as prevailing in the south of england at the commencement of the eocene period. in the eocene strata of north america occur numerous plants belonging to existing types--such as palms, conifers, the magnolia, cinnamon, fig. dog-wood, maple, hickory, poplar, plane, &c. taken as a whole, the eocene flora of north america is nearly related to that of the miocene strata of europe, as well as to that now existing in the american area. we conclude, therefore, that "the forests of the american eocene resembled those of the european miocene, and even of modern america" (dana). [illustration: fig. .--_napadites ellipticus_, the fruit of a fossil palm. london clay, isle of sheppey.] as regards the _animals_ of the eocene period, the _protozoans_ are represented by numerous _foraminifera_, which reach here their maximum of development, both as regards the size of individuals and the number of generic types. many of the eocene foraminifers are of small size; but even these not uncommonly form whole rock-masses. thus, the so-called "miliolite limestone" of the paris basin, largely used as a building-stone, is almost wholly composed of the shells of a small species of _miliola_. the most remarkable, however, of the many members of this group of animals which flourished in eocene times, are the "nummulites" (_nummulina_), so called from their resemblance in shape to coins (lat. _nummus_, a coin). the nummulites are amongst the largest of all known _foraminifera_, sometimes attaining a size of three inches in circumference; and their internal structure is very complex (fig. ). many species are known, and they are particularly characteristic of the middle and upper of these periods--their place being sometimes taken by _orbitoides_, a form very similar to the nummulite in external appearance, but differing in its internal details. in the middle eocene, the remains of nummulites are found in vast numbers in a very widely-spread and easily-recognised formation known as the "nummulitic limestone" (fig. ). according to sir charles lyell, "the nummulitic limestone of the swiss alps rises to more than , feet above the level of the sea, and attains here and in other mountain-chains a thickness of several thousand feet. it may be said to play a far more conspicuous part than any other tertiary group in the solid framework of the earth's crust, whether in europe, asia, or africa. it occurs in algeria and morocco, and has been traced from egypt, where it was largely quarried of old for the building of the pyramids, into asia minor, and across persia by bagdad to the mouths of the indus. it has been observed not only in cutch, but in the mountain-ranges which separate scinde from persia, and which form the passes leading to cabul; and it has been followed still further eastward into india, as far as eastern bengal and the frontiers of china." the shells of nummulites have been found at an elevation of , feet above the level of the sea in western thibet; and the distinguished and philosophical geologist just quoted, further remarks, that "when we have once arrived at the conviction that the nummulitic formation occupies a middle and upper place in the eocene series, we are struck with the comparatively modern date to which some of the greatest revolutions in the physical geography of europe, asia, and northern africa must be referred. all the mountain-chains--such as the alps, pyrenees, carpathians, and himalayas--into the composition of whose central and loftiest parts the nummulitic strata enter bodily, could have had no existence till after the middle eocene period. during that period, the sea prevailed where these chains now rise; for nummulites and their accompanying testacea were unquestionably inhabitants of salt water." [illustration: fig. .--_nummulina loevigata_. middle eocene.] the _coelenterates_ of the eocene are represented principally by _corals_, mostly of types identical with or nearly allied to those now in existence. perhaps the most characteristic group of these is that of the _turbinolidoe_, comprising a number of simple "cup-corals," which probably lived in moderately deep water. one of the forms belonging to this family is here figured (fig. ). besides true corals, the eocene deposits have yielded the remains of the "sea-pens" (_pennatulidoe_) and the branched skeletons of the "sea-shrubs" (_gorgontidoe_). the _echinoderms_ are represented principally by sea-urchins, and demand nothing more than mention. it is to be observed, however, that the great group of the sea-lilies (_crinoids_) is now verging on extinction, and is but very feebly represented. amongst the _mollusca_, the _polyzoans_ and _brachiopods_ also require no special mention, beyond the fact that the latter are greatly reduced in numbers, and belong principally to the existing genera _terebratula_ and _rhynchonella_. the bivalves (_lamellibranchs_) and the univalves (_gasteropods_) are exceedingly numerous, and almost all the principal existing genera are now represented; though less than five percent of the eocene _species_ are identical with those now living. it is difficult to make any selection from the many bivalves which are known in deposits of this age; but species of _cardita, crassatella, leda, cyrena, mactra, cardium, psammobia_, &c., may be mentioned as very characteristic. the _caradita planicosta_ here figured (fig. ) is not only very abundant in the middle eocene, but is very widely distributed, ranging from europe to the pacific coast of north america. the _univalves_ of the eocene are extremely numerous, and generally beautifully preserved. the majority of them belong to that great section of the _gasteropods_ in which the mouth of the shell is notched or produced into a canal (when the shell is said to be "siphonostomatous")--this section including the carnivorous and most highly-organized groups of the class. not only is this the case, but a large number of the eocene univalves belong to types which now attain their maximum of development in the warmer regions of the globe. thus we find numerous species of cones (_conus_), volutes (_voluta_), cowries (_cyproea_, fig. ), olives and rice-shells (_oliva_), mitre-shells (_mitra_), trumpet-shells (_triton_), auger-shells (_terebra_), and fig-shells (_pyrula_). along with these are many forms of _pleurotoma, rostellaria_, spindle-shells (_fusus_), dog-whelks (_nassa_), _murices_, and many round-mouthed ("holostomatous") species, belonging to such genera as _turritella, nerita, natica, scalaria_, &c. the genus _cerithium_ (fig. ), most of the living forms of which are found in warm regions, inhabiting fresh or brackish waters, undergoes a vast development in the eocene period, where it is represented by an immense number of specific forms, some of which attain very large dimensions. in the eocene strata of the paris basin alone, nearly one hundred and fifty species of this genus have been detected. the more strictly fresh-water deposits of the eocene period have also yielded numerous remains of univalves such as are now proper to rivers and lakes, together with the shells of true land-snails. amongst these may be mentioned numerous species of _limnoea_ (fig. ), _physa_ (fig. ), _melania, paludina, planorbis, helix, bulimus_, and _cyclostoma_ (fig. ). [illustration: fig. .--_turbinolia sulcata_, viewed from one side, and from above. eocene.] [illustration: fig. .--_cardita planicosta_. middle eocene.] [illustration: fig. .--_typhis tubifer_, a "siphonostomatous" univalve. eocene.] [illustration: fig. .--cyproea elegans. eocene.] [illustration: fig. .--_cerithium hexagonum_. eocene.] with regard to the _cephalopods_, the chief point to be noticed is, that all the beautiful and complex forms which peculiarly characterised the cretaceous period have here disappeared. we no longer meet with a single example of the turrilite, the baculite, the hamite, the scaphite, or the ammonite. the only exception to this statement is the occurrence of one species of ammonite in the so-called "lignitic formation" of north america; but the beds containing this may possibly be rather referable to the cretaceous--and this exception does not affect the fact that the _ammonitidoe_, as a family, had become extinct before the eocene strata were deposited. the ancient genus _nautilus_ still survives, the sole representative of the once mighty order of the tetrabranchiate cephalopods. in the order of the _dibranchiates_, we have a like phenomenon to observe in the total extinction of the great family of the "belemnites." no form referable to this group has hitherto been found in any tertiary stratum; but the internal skeletons of cuttle-fishes (such as _belosepia_) are not unknown. [illustration: fig. .--_limnoea pyramidalis_. eocene.] [illustration: fig. .--_physa columnaris_. eocene.] [illustration: fig. .--_cyclostoma arnoudii_. eocene.] remains of _fishes_ are very abundant in strata of eocene age, especially in certain localities. the most famous depot for the fossil fishes of this period is the limestone of monte bolca, near verona, which is interstratified with beds of volcanic ashes, the whole being referable to the middle eocene. the fishes here seem to have been suddenly destroyed by a volcanic eruption, and are found in vast numbers. agassiz has described over one hundred and thirty species of fishes from this locality, belonging to seventy-seven genera. all the _species_ are extinct; but about one-half of the _genera_ are represented by living forms. the great majority of the eocene fishes belong to the order of the "bony fishes" (_teleosteans_), so that in the main the forms of fishes characterising the eocene are similar to those which predominate in existing seas. in addition to the above, a few _ganoids_ and a large number of _placoids_ are known to occur in the eocene rocks. amongst the latter are found numerous teeth of true sharks, such as _otodus_ (fig. ) and _carcharodon_. the pointed and serrated teeth of the latter sometimes attain a length of over half a foot, indicating that these predaceous fishes attained gigantic dimensions; and it is interesting to note that teeth, in external appearance very similar to those of the early tertiary genus _carcharodon_, have been dredged from great depths during the recent expedition of the challenger. there also occur not uncommonly the flattened teeth of rays (fig. ), consisting of flat bony pieces placed close together, and forming "a kind of mosaic pavement on both the upper and lower jaws" (owen). [illustration: fig. .--_rhombus minimus_, a small fossil turbot from the eocene tertiary, monte bolca.] [illustration: fig. .--tooth of _otodus obliquus_. eocene.] [illustration: fig. .--flattened dental plates of a ray (_myliobatis edwardsii_). eocene.] in the class of the _reptiles_, the disappearance of the characteristic mesozoic types is as marked a phenomenon as the introduction of new forms. the ichthyosaurs, the plesiosaurs, the pterosaurs, and the mosasaurs of the mesozoic, find no representatives in the eocene tertiary; and the same is true of the deinosaurs, if we except a few remains from the doubtfully-situated "lignitic formation" of the united states, on the other hand, all the modern orders of reptiles are known to have existed during the eocene period. the _chelonians_ are represented by true marine turtles, by "terrapins" (_emydidoe_), and by "soft tortoises" (_trionycidoe_). the order of the snakes and serpents (_ophidia_) makes its appearance here, for the first time under several forms--all of which, however, are referable to the non-venomous group of the "constricting serpents" (_boidoe_). the oldest of these is the _paloeophis toliapicus_ of the london clay of sheppey, first made known to science by the researches of professor owen. the nearly-allied _paloeophis typhoeus_ of the eocene beds of bracklesham appears to have been a boa-constrictor-like snake of about twenty feet in length. similar python-like snakes (_paloeophis, dinophis_, &c.) have been described from the eocene deposits of the united states. true lizards (_lacertilians_) are found in some abundance in the eocene deposits,--some being small terrestrial forms, like the common european lizards of the present day; whilst others equal or exceed the living monitors in size. lastly, the modern order of the _crocodilia_ is largely represented in eocene times, by species belonging to all the existing genera, together with others referable to extinct types. as pointed out by owen, it is an interesting fact that in the eocene rocks of the south-west of england, there occur fossil remains of all the three living types of crocodilians--namely, the gavials, the true crocodiles, and the alligators (fig. )--though at the present day these forms are all geographically restricted in their range, and are never associated together. [illustration: fig. .--upper jaw of alligator. eocene tertiary, isle of wight.] almost all the existing orders of _birds_, if not all, are represented in the eocene deposits by remains often very closely allied to existing types. thus, amongst the swimming birds (_natatores_) we find examples of forms allied to the living pelicans and mergansers; amongst the waders (_grallatores_) we have birds resembling the ibis (the _numenius gypsorum_ of the paris basin); amongst the running birds (_cursores_) we meet with the great _gastornis parisiensis_, which equalled the african ostrich in height, and the still more gigantic _dasornis londinensis_; remains of a partridge represent the scratching birds (_rasores_); the american eocene has yielded the bones of one of the climbing birds (_scansores_), apparently referable to the woodpeckers; the _protornis glarisiensis_ of the eocene schists of glaris is the oldest known example of the perching birds (_insessores_); and the birds of prey (_raptores_) are represented by vultures, owls, and hawks. the toothed birds of the upper cretaceous are no longer known to exist; but professor owen has recently described from the london clay the skull of a very remarkable bird, in which there is, at any rate, an approximation to the structure of _ichthyornis_ and _hesperornis_. the bird in question has been named the _odontopteryx totiapicus_, its generic title being derived from the very remarkable characters of its jaws. in this singular form (fig. ) the margins of both jaws are furnished with tooth-like denticulations, which differ from true teeth in being actually portions of the bony substance of the jaw itself, with which they are continuous, and which were probably encased by extensions of the horny sheath of the bill. these tooth-like processes are of two sizes, the larger ones being comparable to canines; and they are all directed forwards, and have a triangular or compressed conical form. from a careful consideration of all the discovered remains of this bird, professor owen concludes that "_odontopteryx_ was a warm-blooded feathered biped, with wings; and further, that it was web-footed and a fish-eater, and that in the catching of its slippery prey it was assisted by this pterosauroid armature of its jaws." upon the whole, _odontopteryx_ would appear to be most nearly related to the family of the geese (_anserinoe_) or ducks (_anatidoe_); but the extension of the bony substance of the jaws into tooth-like processes is an entirely unique character, in which it stands quite alone. [illustration: fig. .--skull of _odontopteryx toliapicus restored. (after owen.)] the known _mammals_ of the mesozoic period, as we have seen, are all of small size; and with one not unequivocal exception, they appear to be referable to the order of the pouched quadrupeds (_marsupials_), almost the lowest group of the whole class of the mammalia. in the eocene rocks, on the other hand, numerous remains of quadrupeds have been brought to light, representing most of the great mammalian orders now in existence upon the earth, and in many cases indicating animals of very considerable dimensions. we are, in fact, in a position to assert that the majority of the great groups of quadrupeds with which we are familiar at the present day were already in existence in the eocene period, and that their ancient root-stocks were even in this early time separated by most of the fundamental differences of structure which distinguish their living representatives. at the same time, there are some amongst the eocene quadrupeds which have a "generalised" character, and which may be regarded as structural types standing midway between groups now sharply separated from one another. the order of the _marsupials_--including the existing kangaroos, wombats, opossums, phalangers, &c.--is poorly represented in deposits of eocene age. the most celebrated example of this group is the _didelphys gypsorum_ of the gypseous beds of montmartre, near paris, an opossum very nearly allied to the living opossums of north and south america. no member of the _edenates_ (sloths, ant-eaters, and armadillos) has hitherto been detected in any eocene deposit. the aquatic order of the _sirenians_ (dugongs and manatees), with their fish-like bodies and tails, paddle-shaped forelimbs, and wholly deficient hind-limbs, are represented in strata of this age by remains of the ancient "sea-cows," to which the name of _halitherium_ has been applied. nearly allied to the preceding is the likewise aquatic order of the whales and dolphins (_cetaceans_), in which the body is also fish-like, the hind-limbs are wanting, the fore-limbs are converted into powerful "flippers" or swimming-paddles, and the terminal extremity of the body is furnished with a horizontal, tail-fin. many existing cetaceans (such as the whalebone whales) have no true teeth; but others (dolphins, porpoises, sperm whales) possess simple conical teeth. in strata of eocene age, however, we find a singular group of whales, constituting the genus _zeuglodon (fig. ), in which the teeth differed from those of all existing forms in being of two kinds,--the front ones being conical incisors, whilst the back teeth or molars have serrated triangular crowns, and are inserted in the jaw by two roots. each molar (fig. , a) looks as if it were composed of two separate teeth united on one side by their crowns; and it is this peculiarity which is expressed by the generic name (gr. _zeugle_, a yoke; _odous_, tooth). the best-known species of the genus is the _zeuglodon cetoides_ of owen, which attained a length of seventy feet. remains of these gigantic whales are very common in the "jackson beds" of the southern united states. so common are they that, according to dana, "the large vertebræ, some of them a foot and a half long and a foot in diameter, were formerly so abundant over the country, in alabama, that they were used for making walls, or were burned to rid the fields of them." [illustration: fig. .--_zeuglodon cetoides_. a, molar tooth of the natural size; b, vertebra, reduced in size. from the middle eocene of the united states. (after lyell.)] the great and important order of the hoofed quadrupeds (_ungulata_) is represented in the eocene by examples of both of its two principal sections--namely, those with an uneven number of toes (one or three) on the foot (_perissodactyle ungulates_), and those with an even number of toes (two or four) to each foot (_artiodactyle ungulates_). amongst the odd-toed ungulates, the living family of the tapirs (_tapirdoe_) is represented by the genus _coryphodon_ of owen. nearly related to the preceding are the species of _paloeotherium_, which have a historical interest as being amongst the first of the tertiary mammals investigated by the illustrious cuvier. several species of _paloeothere_ are known, varying greatly in size, the smallest being little bigger than a hare, whilst the largest must have equalled a good-sized horse in its dimensions. the species of _paloeotherium_ appear to have agreed with the existing tapirs in possessing a lengthened and flexible nose, which formed a short proboscis or trunk (fig. ), suitable as an instrument for stripping off the foliage of trees--the characters of the molar teeth showing them to have been strictly herbivorous in their habits. they differ, however, from the tapirs, amongst other characters, in the fact that both the fore and the hind feet possessed three toes each; whereas in the latter there are four toes on each fore-foot, and the hind-feet alone are three-toed. the remains of _paloeotheria_ have been found in such abundance in certain localities as to show that these animals roamed in great herds over the fertile plains of france and the south of england during the later portion of the eocene period. the accompanying illustration (fig. ) represents the notion which the great cuvier was induced by his researches to form as to the outward appearance of _paloeotherium magnum_. recent discoveries, however, have rendered it probable that this restoration is in some important respects inaccurate. instead of being bulky, massive, and more or less resembling the living tapirs in form, it would rather appear that _paloeotherium magnum_ was in reality a slender, graceful, and long-necked animal, more closely resembling in general figure a llama, or certain of the antelopes. [illustration: fig. .--outline of _paloeotherium magnum_, restored. upper eocene, europe. (after cuvier.)] the singular genus _anchitherium_ forms a kind of transition between the _paloeotheria_ and the true horses (_equidoe_). the horse (fig. , d) possesses but one fully-developed toe to each foot, this being terminated by a single broad hoof, and representing the _middle_ toe--the _third_ of the typical five-fingered or five-toed limb of quadrupeds in general. in addition, however, to this fully-developed toe, each foot in the horse carries two rudimentary toes which are concealed beneath the skin, and are known as the "splint-bones." these are respectively the _second_ and _fourth_ toes, in an aborted condition; and the first and fifth toes are wholly wanting. in _hipparion_ (fig. , c), the foot is essentially like that of the modern horses, except that the second and fourth toes no longer are mere "splint-bones," hidden beneath the skin; but have now little hoofs, and hang freely, but uselessly, by the side of the great middle toe, not being sufficiently developed to reach the ground. in _anchitherium_, again (fig. , b), the foot is three-toed, like that of _hipparion_; but the two lateral toes (the second and fourth) are so far developed that they now reach the ground. the _first_ digit (thumb or great toe) is still wanting; as also is the _fifth_ digit (little finger or little toe). lastly, the eocene rocks have yielded in north america the remains of a small equine quadruped, to which marsh has given the name of _orohippus_. in this singular form--which was not larger than a fox--the foot (fig. , a) carries _four_ toes, all of which are hoofed and touch the ground, but of which the _third_ toe is still the largest. the _first_ toe (thumb or great toe) is still wanting; but in this ancient representative of the horses, the _fifth_ or "little" toe appears for the first time. as all the above-mentioned forms succeed one another in point of time, it may be regarded as probable that we shall yet be able to point, with some certainty, to some still older example of the _equidoe_, in which the first digit is developed, and the foot assumes its typical five-fingered condition. [illustration: fig. .--skeleton of the foot in various forms belonging to the family of the _equidoe_. a, foot of _orohippus_, eocene; b, foot of _anchitherium</>, upper eocene and lower miocene; c, foot of _hipparion_, upper miocene and pliocene: d, foot of horse (_equus_), pliocene and recent. the figures indicate the numbers of the digits in the typical five-fingered hand of mammals. (after marsh.)] passing on to the even-toed or _artiodactyle ungulates_, no representative of the _hippotamus_ seems yet to have existed, but there are several forms (_choeropotamus, hyopotamus_, &c.) more or less closely allied to the pigs (_suida_); and the singular group of the _anoplotheridoe_ may be regarded as forming a kind of transition between the swine and the ruminants. the _anoplotheria_ (fig. ) were slender in form, the largest not exceeding a donkey in size, with long tails, and having the feet terminated by two hoofed toes each, sometimes with a pair of small accessory hoofs as well. the teeth exhibit the peculiarity that they are arranged in a continuous series, without any gap or interval between the molars and the canines; and the back teeth, like those of all the ungulates, are adapted for grinding vegetable food, their crowns resembling in form those of the true ruminants. the genera _dichobune_ and _xiphodon_, of the middle and upper eocene, are closely related to _anoplotherium_, but are more slender and deer-like in form. no example of the great ruminant group of the ungulate quadrupeds has as yet been detected in deposits of eocene age. [illustration: fig. .--_anoplotherium commune_. eocene tertiary, france. (after cuvier.)] whilst true ruminants appear to be unknown, the eocene strata of north america have yielded to the researches of professor marsh examples of an extraordinary group (_dinocerata_), which may be considered as in some respects intermediate between the ungulates and the proboscideans. in _dinoceras_ itself (fig. ) we have a large animal, equal in dimensions to the living elephants, which it further resembles in the structure of the massive limbs, except that there are only four toes to each foot. the upper jaw was devoid of front teeth, but there were two very large canine teeth, in the form of tusks directed perpendicularly downwards; and there was also a series of six small molars on each. each upper jaw-bone carried a bony projection, which was probably of the nature of a "horn-core," and was originally sheathed in horn. two similar, but smaller, horn-cores are carried on the nasal bones; and two much larger projections, also probably of the nature of horn-cores, were carried upon the forehead. we may thus infer that _dinoceras_ possessed three pairs of horns, all of which resembled the horns of the sheep and oxen in consisting of a central bony "core," surrounded by a horny sheath. the nose was not prolonged into a proboscis or "trunk," as in the existing elephants; and the tail was short and slender. many forms of the _dinocerata_ are known; but all these singular and gigantic quadrupeds appear to have been confined to the north american continent, and to be restricted to the eocene period. [illustration: fig. .--skull of _dinoceras mirabilis_, greatly reduced. eocene, north america. (after marsh.)] the important order of the elephants (_proboscidea_) is also not known to have come into existence during the eocene period. on the other hand, the great order of the beasts of prey (_carnivora_) is represented in eocene strata by several forms belonging to different types. thus the _ardocyon_ presents us with an eocene carnivore more or less closely allied to the existing racoons; the _paloeonyctis_ appears to be related to the recent civet-cats; the genus _hyoenodon_ is in some respects comparable to the living hyænas; and the _canis parisiensis_ of the gypsum-bearing beds of montmartre may perhaps be allied to the foxes. [illustration: fig. .--portion of the skeleton of _vespertilio parisienis_. eocene tertiary, france.] the order of the bats (_cheiroptera_) is represented in eocene strata of the paris basin (gypseous series of montmartre) by the _vespertilio parisiensis_ (fig. ), an insect-eating bat very similar to some of the existing european forms. lastly, the eocene deposits have yielded more or less satisfactory evidence of the existence in europe at this period of examples of the orders of the gnawing mammals (_rodentia_), the insect-eating mammals (_insectivora_), and the monkeys (_quadrumana_).[ ] [footnote : a short list of the more important works relating to the eocene rocks and fossils will be given after all the tertiary deposits have been treated of.] chapter xix. the miocene period. the miocene rocks comprise those tertiary deposits which contain less than about per cent of existing species of shells (_mollusca_), and more than per cent--or those deposits in which the proportion of living shells is less than of extinct species. they are divisible into a _lower miocene_ (_oligocene_) and an _upper miocene_ series. in _britain_, the miocene rocks are very poorly developed, one of their leading developments being at bovey tracy in devonshire, where there occur sands, clays, and beds of lignite or imperfect coal. these strata contain numerous plants, amongst which are vines, figs, the cinnamon-tree, palms, and many conifers, especially those belonging to the genus sequoia (the "red-foods"). these bovey tracy lignites are of lower miocene age, and they are lacustrine in origin. also of lower miocene age are the so-called "hempstead beds" of yarmouth in the isle of wight. these attain a thickness of less than feet, and are shown by their numerous fossils to be principally a true marine formation. lastly, the duke of argyll, in , showed that there existed at ardtun, in the island of mull, certain tertiary strata containing numerous remains of plants; and these also are now regarded as belonging to the lower miocene. in _france_, the lower miocene is represented in auvergne, cantal, and velay, by a great thickness of nearly horizontal strata of sands, sandstone, clays, marls, and limestones, the whole of fresh-water origin. the principal fossils of these lacustrine deposits are _mammalia_, of which the remains occur in great abundance. in the valley of the loire occur the typical european deposits of upper miocene age. these are known as the "faluns," from a provincial term applied to shelly sands, employed to spread upon soils which are deficient in lime; and the upper miocene is hence sometimes spoken of as the "falunian" formation. the faluns occur in scattered patches, which are rarely more than feet in thickness, and consist of sands and marls. the fossils are chiefly marine; but there occur also land and fresh-water shells, together with the remains of numerous mammals. about per cent of the shells of the faluns are identical with existing species. the sands, limestones, and marls of the department of gers, near the base of the pyrenees, rendered famous by the number or mammalian remains exhumed from them by m. lartet, also belong to the age of the faluns. in _switzerland_, between the alps and the jura, there occurs a great series of miocene deposits, known collectively as the "molasse," from the soft nature of a greenish sandstone, which constitutes one of its chief members. it attains a thickness of many thousands of feet, and rises into lofty mountains, some of which--as the rigi--are more than feet in height. the middle portion of the molasse is of marine origin, and is shown by its fossils to be of the age of the faluns; but the lower and upper portions of the formation are mainly or entirely of fresh-water origin. the lower molasse (of lower miocene age) has yielded about species of plants, mostly of tropical or sub-tropical forms. the upper molasse has yielded about the same number of plants, with about species of insects, such as wood-eating beetles water-beetles, white ants, dragon-flies, &c. in _belgium_, strata of both lower and upper miocene age are known,--the former (_rupelian clays_) containing numerous marine fossils; whilst the latter (_bolderberg sands_) have yielded numerous shells corresponding with those of the faluns. in _austria_, miocene strata are largely developed, marine beds belonging to both the lower and upper division of the formation occurring extensively in the vienna basin. the well-known brown coals of radaboj, in croatia, with numerous plants and insects, are also of lower miocene age. in _germany_, deposits belonging to both the lower and upper division of the miocene formation are extensively developed. to the former belong the marine strata of the mayence basin, and the marine _rupelian clay_ near berlin; whilst a celebrated group of strata belonging to the upper miocene occurs near epplesheim, in hesse-darmstadt, and is well known for the number of its mammalian remains. in _greece_, at pikermé, near athens, there occurs a celebrated deposit of upper miocene age, well known to palæontologists through the researches of m. m. wagner, roth, and gaudry upon the numerous mammalia which it contains. in _italy_, also, strata of both lower and upper miocene age are well developed in the neighbourhood of turin. in the _siwâlik hills_, in india, at the southern foot of the himalayas, occurs a series of upper miocene strata, which have become widely celebrated through the researches of dr falconer and sir proby cautley upon the numerous remains of mammals and reptiles which they contain. beds of corresponding age, with similar fossils, are known to occur in the island of perim in the gulf of cambay. lastly, miocene deposits are found in _north america_, in new jersey, maryland, virginia, missouri, california, oregon, &c., attaining a thickness of feet or more. they consist principally of clays, sands, and sandstones, sometimes of marine and sometimes of fresh-water origin. near richmond, in virginia, there occurs a remarkable stratum, wrongly called "infusorial earth," which is occasionally feet in thickness, and consists almost wholly of the siliceous envelopes of certain low forms of plants (diatoms), along with the spicules of sponges and other siliceous organisms (see fig. ). the _white river group_ of hayden occurs in the upper missouri region, and is largely exposed over the barren and desolate district known as the "mauvaises terres." they have a thickness of feet or more, and contain numerous remains of mammals. they are of lacustrine origin, and are believed to be of the age of the lower miocene. upon the whole, about from to per cent of the _mollusca_ of the american miocene are identical with existing species. in addition to the regions previously enumerated, miocene strata are known to be developed in _greenland, iceland, spitzbergen_, and in other areas of less importance. the _life_ of the miocene period is extremely abundant, and, from the nature of the deposits of this age, also extremely varied in its character. the marine beds of the formation have yielded numerous remains of both vertebrate and invertebrate sea-animals; whilst the fresh-water deposits contain the skeletons of such shells, fishes, &c., as now inhabit rivers or lakes. both the marine and the lacustrine beds have been shown to contain an enormous number of plants, the latter more particularly; whilst the brown coals of the formation are made up of vegetable matter little altered from its original condition. the remains of air-breathing animals, such as insects, reptiles, birds, and mammals, are also abundantly found, more especially in the fresh-water beds. the _plants_ of the miocene period are extraordinarily numerous, and only some of the general features of the vegetation of this epoch can be indicated here. our chief sources of information as to the miocene plants are the brown coals of germany and austria, the lower and upper molasse of switzerland, and the miocene strata of the arctic regions. the lignites of austria have yielded very numerous plants, chiefly of a tropical character--one of the most noticeable forms being a palm of the genus _sabal_ (fig. , b), now found in america. the plants of the lower miocene of switzerland are also mostly of a tropical character, but include several forms now found in north america, such as a tulip-tree (_liriodendron_) and a cypress (_taxodium_). amongst the more remarkable forms from these beds may be mentioned fan-palms (_chamoerops_, fig , a), numerous tropical ferns, and two species of cinnamon. the plant-remains of the upper molasse of switzerland indicate an extraordinarily rank and luxuriant vegetation, composed mainly of plants which now live in warm countries. among the commoner plants of this formation may be enumerated many species of maple (_acer_), plane-trees (_platanus_ fig. ), cinnamon-trees (fig. ), and other members of the _lauraceoe_, many species of _proteaccoe_ (_banksia, grevillea_, &c.), several species of sarsaparilla (_smilax_), palms, cypresses, &c. [illustration: fig. .--miocene palms a, _chamoerops helvetica_; b, _sabal major_. lower miocene of switzerland and france.] [illustration: fig. .--_platanus aceroides_, an upper miocene plane-tree. a, leaf; b, the core of a bundle of fruits; c, a single fruit.] [illustration: fig. .--_cinnamomum polymorphum_. a, leaf; b, flower. upper miocene.] in britain, the lower miocene strata of bovey tracy have yielded remains of ferns, vines, fig, cinnamon, _proteaccoe_, &c., along with numerous conifers. the most abundant of these last is a gigantic pine--the _sequoia couttsioe_--which is very nearly allied to the huge _sequoia_ (_wellingtonia_) _gigantea_ of california. a nearly-allied form (_sequoia langsdorffi_) has been detected in the leaf-bed of ardtun, in the hebrides. in greenland, as well as in other parts of the arctic regions, miocene strata have been discovered which have yielded a great number of plants, many of which are identical with species found in the european miocene. amongst these plants are found many trees, such as conifers, beeches, oaks, maples, plane-trees, walnuts, magnolias, &c., with numerous shrubs, ferns, and other smaller plants. with regard to the miocene flora of the arctic regions, sir charles lyell remarks that "more than thirty species of coniferæ have been found, including several sequoias (allied to the gigantic wellingtonia of california), with species of _thujopsis_ and _salisburia_, now peculiar to japan. there are also beeches, oaks, planes, poplars, maples, walnuts, limes, and even a magnolia, two cones of which have recently been obtained, proving that this splendid evergreen not only lived but ripened its fruit within the arctic circle. many of the limes, planes, and oaks were large-leaved species; and both flowers and fruits, besides immense quantities of leaves, are in many cases preserved. among the shrubs are many evergreens, as _andromeda_, and two extinct genera, _daphnogene_ and _m'clintockia_, with fine leathery leaves, together with hazel, blackthorn, holly, logwood, and hawthorn. a species of zamia (_zimites_) grew in the swamps, with _potamogeton, sparganium_, and _menyanthes_; while ivy and villes twined around the forest-trees, and broad-leaved ferns grew beneath their shade. even in spitzbergen, as far north as lat. ° ', no less than ninety-five species of fossil plants have been obtained, including _taxodium_ of two species, hazel, poplar, alder, beech, plane-tree, and lime. such a vigorous growth of trees within ° of the pole, where now a dwarf willow and a few herbaceous plants form the only vegetation, and where the ground is covered with almost perpetual snow and ice, is truly remarkable." taking the miocene flora as a whole, dr heer concludes from his study of about plants contained in the european miocene alone, that the miocene plants indicate tropical or sub-tropical conditions, but that there is a striking inter-mixture of forms which are at present found in countries widely removed from one another. it is impossible to state with certainty how many of the miocene plants belong to existing species, but it appears that the larger number are extinct. according to heer, the american types of plants are most largely represented in the miocene flora, next those of europe and asia, next those of africa, and lastly those of australia. upon the whole, however, the miocene flora of europe is mostly nearly allied to the plants which we now find inhabiting the warmer parts of the united states; and this has led to the suggestion that in miocene times the atlantic ocean was dry land, and that a migration of american plants to europe was thus permitted. this view is borne out by the fact that the miocene plants of europe are most nearly allied to the living plants of the eastern or atlantic seaboard of the united states, and also by the occurrence of a rich miocene flora in greenland. as regards greenland, dr heer has determined that the miocene plants indicate a temperate climate in that country, with a mean annual temperature at least ° warmer than it is at present. the present limit of trees is the isothermal which gives the mean temperature of fahr. in july, or about the parallel of ° n. latitude. in miocene times, however, the limes, cypresses, and plane-trees reach the th degree of latitude, and the pines and poplars must have ranged even further north than this. the _invertebrate animals_ of the miocene period are very numerous, but they belong for the most part to existing types, and they can only receive scanty consideration here. the little shells of _foraminifera_ are extremely abundant in some beds, the genera being in many cases such as now flourish abundantly in our seas. the principal forms belong to the genera _textularia_ (fig. ), _robulina, glandulina, polystomella, amplistegina_, &c. corals are very abundant, in many instances forming regular "reefs;" but all the more important groups are in existence at the present day. the red coral (_corallium_), so largely sought after as an ornamental material, appears for the first time in deposits of this age. amongst the _echinoderms_, we meet with heart-urchins (_spatangus_), cake-urchins (_scutella_; fig. ), and various other forms, the majority of which are closely allied to forms now in existence. [illustration: fig. .--_textularia meyeriana_, greatly enlarged. miocene tertiary.] numerous crabs and lobsters represent the _crustacea_; but the most important of the miocene articulate animals are the _insects_. of these, more than thirteen hundred species have been determined by dr heer from the miocene strata of switzerland alone. they include almost all the existing orders of insects, such as numerous and varied forms of beetles (_coleoptera_), forest-bugs (_hemiptera_), ants (_hymenoptera_), flies (_diptera_), termites and dragon-flies (_neuroptera_), grasshoppers (_orthoptera_), and butterflies (_lepidoptera_). one of the latter, the well-known _vanessa pluto_ of the brown coals of croatia, even exhibits the pattern of the wing, and to some extent its original coloration; whilst the more durably-constructed insects are often in a state of exquisite preservation. [illustration: fig. .--different views of _scutella subrotunda_, a miocene "cake-urchin" from the south of france.] the _mollusca_ of the miocene period are very numerous, but call for little special comment. upon the whole, they are generically very similar to the shell-fish of the present day; whilst, as before stated, from fifteen to thirty per cent of the _species_ are identical with those now in existence. so far as the european area is concerned, the molluscs indicate a decidedly hotter climate than the present one, though they have not such a distinctly tropical character as is the case with the eocene shells. thus we meet with many cones, volutes, cowries, olive-shells, fig-shells, and the like, which are decidedly indicative of a high temperature of the sea. _polyzoans_ are abundant, and often attain considerable dimensions; whilst _brachiopods_, on the other hand, are few in number. bivalves and _univalves_ are extremely plentiful; and we meet here with the shells of winged-snails (_pteropods_), belonging to such existing genera as _hyalea_ (fig. ) and _cleodora_. lastly, the _cephalopods_ are represented both by the chambered shells of _nautili_ and by the internal skeletons of cuttle-fishes (_spirulirostra_.) [illustration: fig. .--different views of the shell of _hyalea orbignyana_, a miocene pteropod.] the _fishes_ of the miocene period are very abundant but of little special importance. besides the remains of bony fishes, we meet in the marine deposits of this age with numerous pointed teeth belonging to different kinds of sharks. some of the genera of these--such as _carcharodon_ (fig. ), _oxyrhina_ (fig. ), _lamna_, and _galeocerdo_--are very widely distributed, ranging through both the old and new worlds; and some of the species attain gigantic dimensions. amongst the _amphibians_ we meet with distinctly modern types, such as frogs (_rana_) and newts or salamanders. the most celebrated of the latter is the famous _andrias scheuchzeri_ (fig. ), discovered in the year in the fresh-water miocene deposits of oeningen, in switzerland. the skeleton indicates an animal nearly five feet in length; and it was originally described by scheuchzer, a swiss physician, in a dissertation published in , as the remains of one of the human beings who were in existence at the time of the noachian deluge. hence he applied to it the name of _homo diluvii testis_. in reality, however, as shown by cuvier, we have here the skeleton of a huge newt, very closely allied to the giant salamander (_menopoma maxima_) of java. [illustration: fig. .--tooth of _oxyrhina xiphodon_. miocene.] [illustration: fig. .--tooth of _carcharodon productus_. miocene.] the remains of _reptiles_ are far from uncommon in the miocene rocks, consisting principally of chelonians and crocodilians. the land-tortoises (_testudinidoe_) make their first appearance during this period. the most remarkable form of this group is the huge _colossochelys atlas_ of the upper miocene deposits of the siwâlik hills in india, described by dr falconer and sir proby cautley. far exceeding any living tortoise in its dimensions, this enormous animal is estimated as having had a length of about twenty feet, measured from the tip of the snout to the extremity of the tail, and to have stood upwards of seven feet high. all the details of its organisation, however, prove that it must have been "strictly a land animal, with herbivorous habits, and probably of the most inoffensive nature." the accomplished palæontologist just quoted, shows further that some of the traditions of the hindoos would render it not improbable that this colossal tortoise had survived into the earlier portion of the human period. of the _birds_ of the miocene period it is sufficient to remark that though specifically distinct, they belong, so far as known, wholly to existing groups, and therefore present no points of special palæontological interest. the _mammals_ of the miocene are very numerous, and only the more important forms can be here alluded to. amongst the _marsupials_, the old world still continued to possess species of opossum (_didephys_), allied to the existing american forms. the _edentates_ (sloths, armadillos, and ant-eaters), at the present day mainly south american, are represented by two large european forms. one of these is the large _macrotherium giganteum_ of the upper miocene of gers in southern france, which appears to hare been in many respects allied to the existing scaly ant-eaters or pangolins, at the same time that the disproportionately long fore-limbs would indicate that it possessed the climbing habits of the sloths. the other is the still more gigantic _ancylotherium pentelici_ of the upper miocene of pikermé, which seems to have been as large as, or larger than, the rhinoceros, and which must have been terrestrial in its habits. this conclusion is further borne out by the comparative equality of length which subsists between the fore and hind limbs, and is not affected by the curvature and crookedness of the claws, this latter feature being well marked in such existing terrestrial edentates as the great ant-eater. [illustration: fig. .--front portion of the skeleton of _andrias scheuchzeri_, a giant salamander from the miocene tertiary of oeningen, in switzerland. reduced in size.] the aquatic _sirenians_ and _cetaceans_ are represented in miocene times by various forms of no special importance. amongst the former, the previously existing genus _halitherium_ continued to survive, and amongst the latter we meet with remains of dolphins and of whales of the "zeuglodont" family. we may also note here the first appearance of true "whalebone whales," two species of which, resembling the living "right whale" of arctic seas, and belonging to the same genus (_baloena_), have been detected in the miocene beds of north america. the great order of the _ungulates_ or hoofed quadrupeds is very largely developed in strata of miocene age, various new types of this group making their appearance here for the first time, whilst some of the characteristic genera of the preceding period are still represented under new shapes. amongst the odd-toed or "perissodactyle" ungulates, we meet for the first time with representatives of the family _rhinoceridoe_ comprising only the existing rhinoceroses. in india in the upper miocene beds of the siwâlik hills, and in north america, several species of rhinoceros have been detected, agreeing with the existing forms in possessing three toes to each foot, and in having one or two solid fibrous "horns" carried upon the front of the head. on the other hand, the forms of this group which distinguish the miocene deposits of europe appear to have been for the most part hornless, and to have resembled the tapirs in having three-toed hind-feet, but four-toed fore-feet. the family of the tapirs is represented, both in the old and new worlds, by species of the genus _lophiodon_, some of which were quite diminutive in point of size, whilst others attained the dimensions of a horse. nearly allied to this family, also, is the singular group of quadrupeds which marsh has described from the miocene strata of the united states under the name of _brontotheridoe_. these extraordinary animals, typified by _brontotherium_ (fig. ) itself, agree with the existing tapirs of south america and the indian archipelago in having the fore-feet four-toed, whilst the hind-feet are three-toed; and a further point of resemblance is found in the fact (as shown by the form of the nasal bones) that the nose was long and flexible, forming a short movable proboscis or trunk, by means of which the animal was enabled to browse on shrubs or trees. they differ, however, from the tapirs, not only in the apparent presence of a long tail, but also in the possession of a pair of very large "horn-cores," carried upon the nasal bones, indicating that the animal possessed horns of a similar structure to those of the "hollow-horned" ruminants (_e.g._, sheep and oxen). _brontotherium gigas_ is said to be nearly as large as an elephant, whilst _b. ingens_ appears to have attained dimensions still more gigantic. the well-known genus _titanotherium_ of the american miocene would also appear to belong to this group. [illustration: fig. .--skull of _brontotherium ingens_. miocene tertiary, united states. (after marsh.)] the family of the horses (_equidoe_) appears under various forms in the miocene, but the most important and best known of these is _hipparion_. in this genus the general conformation of the skeleton is extremely similar to that of the existing horses, and the external appearance of the animal must have been very much the same. the foot of _hipparion_, however, as has been previously mentioned, differed from that of the horse in the fact that whilst both possess the middle toe greatly developed and enclosed in a broad hoof, the former, in addition, possessed two lateral toes, which were sufficiently developed to carry hoofs, but were so far rudimentary that they hung idly by the side of the central toe without touching the ground (see fig. ). in the horse, on the other hand, these lateral toes, though present, are not only functionally useless, but are concealed beneath the skin. remains of the _hipparion_ have been found in various regions in europe and in india; and from the immense quantities of their bones found in certain localities, it may be safely inferred that these middle tertiary ancestors of the horses lived, like their modern representatives, in great herds, and in open grassy plains or prairies. amongst the even-toed or _artiodactyle_ ungulates, we for the first time meet with examples of the _hippopotamus_, with its four-toed feet, its massive body, and huge tusk-like lower canine teeth. the miocene deposits of europe have not hitherto yielded any remains of _hippopotamus_; but several species have been detected in the upper miocene of the siwâlik hills by dr falconer and sir proby cautley. these ancient indian forms, however, differ from the existing _hippopotamus amphibius_ of africa in the fact that they possessed six incisor teeth in each jaw (fig. ), whereas the latter has only four. [illustration: fig. .--a, skull of _hippopotamus sivalensis_, viewed from below, one-eighth of the natural size; b, molar tooth of the same, showing the surface of the crown, one-half of the natural size: c, front of the lower jaw of the same, showing the six incisors and the tusk-like canines, one-eighth of the natural size. upper miocene, siwâlik hills; (after falconer and cautley.)] amongst the other even-toed ungulates, the family of the pigs (_suida_) is represented by true swine (_sus erymanthius_), peccaries (_dicotyles antiquus_), and by forms which, like the great _elotherium_ of the american miocene, have no representative at the present day. the upper miocene of india has yielded examples of the camels. small musk-deer (_amphitragulus_ and _dremotherium_) are known to have existed in france and greece; and the true deer (_cervidoe_), with their solid bony antlers, appear for the first time here in the person of species allied to the living stags (_cervus_), accompanied by the extinct genus _dorcatherium_. the giraffes (_camelopardalidoe_), now confined to africa, are known to have lived in india and greece; and the allied _helladotherium_, in some respects intermediate between the giraffes and the antelopes, ranged over southern europe from attica to france. the great group of the "hollow-horned" ruminants (_cavicornia_), lastly, came into existence in the miocene period; and though the typical families of the sheep and oxen are apparently wanting, there are true antelopes, together with forms which, if systematically referable to the _antilopidoe_, nevertheless are more or less clearly transitional between this and the family of the sheep and goats. thus the _paloeoreas_ of the upper miocene of greece may be regarded as a genuine antelope; but the _tragoceras_ of the same deposit is intermediate in its characters between the typical antelopes and the goats. perhaps the most remarkable, however, of these miocene ruminants is the _sivatherium giganteum_ (fig. ) of the siwâlik hills, in india. in this extraordinary animal there were two pairs of horns, supported by bony "horn-cores," so that there can be no hesitation in referring _sivatherium_ to the cavicorn ruminants. if all these horns had been simple, there would have been no difficulty in considering _sivatherium_ as simply a gigantic four-horned antelope, essentially similar to the living _antilope_ (_tetraceros_) _quadricornis_ of india. the hinder pair of horns, however, is not only much larger than the front pair, but each possesses two branches or snags--a peculiarity not to be paralleled amongst any existing antelope, save the abnormal prongbuck (_antilocapra_) of north america. dr murie, however, in an admirable memoir on the structure and relationships of _sivatherium_, has drawn attention to the fact that the prongbuck sheds the _sheath_ of its horns annually, and has suggested that this may also have been the case with the extinct form. this conjecture is rendered probable, amongst other reasons, by the fact that no traces of a horny sheath surrounding the horn-cores of the indian fossil have been as yet detected. upon the whole, therefore, we may regard the elephantine _sivatherium_ as being most nearly allied to the prongbuck of western america, and thus as belonging to the family of the antelopes. [illustration: fig. .--skull of _sivatherium giganteum_, reduced in size. miocene, india. (after murie.)] it is to the miocene period, again, to which we must refer the first appearance of the important order of the elephants and their allies (_proboscideans_), all of which are characterised by their elongated trunk-like noses, the possession of five toes to the foot, the absence of canine teeth, the development of two or more of the incisor teeth into long tusks, and the adaptation of the molar teeth to a vegetable diet. only three generic groups of this order are known-namely, the extinct _deinotherium_, the equally extinct _mastodons_, and the _elephants_; and all these three types are known to have been in existence as early as the miocene period, the first of them being exclusively confined to deposits of this age. of the three, the genus _deinotherium_ is much the most abnormal in its characters; so much so, that good authorities regard it as really being one of the sea-cows (_sirenia_)--though this view has been rendered untenable by the discovery of limb-bones which can hardly belong to any other animal, and which are distinctly proboscidean in type. the most celebrated skull of the deinothere (fig. ) is one which was exhumed from the upper miocene deposits of epplesheim, in hesse-darmstadt, in the year . this skull was four and a half feet in length, and indicated an animal larger than any existing species of elephant. the upper jaw is destitute of incisor or canine teeth, but is furnished on each side with five molars, which are opposed to a corresponding series of grinding teeth in the lower jaw. no canines are present in the lower jaw; but the front portion of the jaw is abruptly bent downwards, and carries two huge tusk-like incisor teeth, which are curved downwards and backwards, and the use of which is rather problematical. not only does the deinothere occur in europe, but remains belonging to this genus have also been detected in the siwâlik hills, in india. [illustration: fig. .--skull of _deinotherium giganteum_, greatly reduced. from the upper micene of germany.] the true elephants (_elephas_) do not appear to have existed during the miocene period in europe, but several species have been detected in the upper miocene deposits of the siwâlik hills, in india. the fossil forms, though in all cases specifically, and in some cases even sub-generically, distinct, agree with those now in existence in the general conformation of their skeleton, and in the principal characters of their dentition. in all, the canine teeth are wanting in both jaws; and there are no incisor teeth in the lower jaw, whilst there are two incisors in the front of the upper jaw, which are developed into two huge "tusks." there are six molar teeth on each side of both the upper and lower jaw, but only one, or at most a part of two, is in actual use at any given time; and as this becomes worn away, it is pushed forward and replaced by its successor behind it. the molars are of very large size, and are each composed of a number of transverse plates of enamel united together by ivory; and by the process of mastication, the teeth become worn down to a flat surface, crossed by the enamel-ridges in varying patterns; these patterns are different in the different species of elephants, though constant for each; and they constitute one of the most readily available means of separating the fossil forms from one another. of the seven miocene elephants of india, as judged by the characters of the molar, teeth, two are allied to the existing indian elephant, one is related to the living african elephant, and the remaining four are in some respects intermediate between the true elephants and the mastodons. [illustration: fig. .--a, molar tooth of _elephas planifrons_, one-third of the natural size, showing the grinding surface--from the upper miocene of india; b, profile view of the last upper molar of _mastodon sivalensis_, one-third of the natural size--from the upper miocene of india. (after falconer.)] the _mastodons_, lastly, though quite elephantine in their general characters, possess molar teeth which have their crowns furnished with conical eminences or tubercles placed in pairs (fig. , b), instead of having the approximately flat surface characteristic of the grinders of the elephants. as in the latter, there are two upper incisor teeth, which grow permanently during the life of the animal, and which constitute great tusks; but the mastodons, in addition, often possess two lower incisors, which in some cases likewise grow into small tusks. three species of _mastodon_ are known to occur in the upper miocene of the siwâlik hills of india; and the miocene deposits of the european area have yielded the remains of four species, of which the best known are the _m. longirostris_ and the _m. angustidens_. whilst herbivorous quadrupeds, as we have seen, were extremely abundant during miocene times, and often attained gigantic dimensions, beasts of prey (_carnivora_) were by no means wanting, most of the principal existing families of the order being represented in deposits of this age. thus, we find aquatic carnivores belonging to both the living groups of the seals and walruses; true bears are wanting, but their place is filled by the closely-allied genus _amphicyon_, of which various species are known; weasels and otters were not unknown, and the _hyoenictis_ and _iditherium_ of the upper miocene of greece are apparently intermediate between the civet-cats and the hyænas; whilst the great cats of subsequent periods are more than adequately represented by the huge "sabre-toothed tiger" (_machairodus_), with its immense trenchant and serrated canine teeth. amongst the _rodent_ mammals, the miocene rocks have yielded remains of rabbits, porcupines (such as the _hystrix primigenius_ of greece), beavers, mice, jerboas, squirrels, and marmots. all the principal living groups of this order were therefore differentiated in middle tertiary times. the _cheiroptera_ are represented by small insect-eating bats; and the order of the insectivorous mammals is represented by moles, shrew-mice, and hedgehogs. [illustration: fig. .--lower jaw of _pliopithcus antiquus_. upper miocene, france.] lastly, the monkeys (_quadrumana_) appear to have existed during the miocene period under a variety of forms, remains of these animals having been found both in europe and in india; but no member of this order has as yet been detected in the miocene tertiary of the north american continent. amongst the old world monkeys of the miocene, the two most interesting are the _pliopithecus_ and _dryopithecus_ of france. the former of these (fig. ) is supposed to have been most nearly related to the living _semnopitheci_ of southern asia, in which case it must have possessed a long tail. the _mesopithecus_ of the upper miocene of greece is also one of the lower monkeys, as it is most closely allied to the existing macaques. on the other hand, the _dryopithecus_ of the french upper miocene is referable to the group of the "anthropoid apes," and is most nearly related to the gibbons of the present day, in which the tail is rudimentary and there are no cheek-pouches. _dryopithecus_ was, also, of large size, equalling man in stature, and apparently living amongst the trees and feeding upon fruits. chapter xx. the pliocene period. the highest division of the tertiary deposits is termed the _pliocene_ formation, in accordance with the classification proposed by sir charles lyell. the pliocene formations contain from to per cent of existing species of _mollusca_, the remainders belonging to extinct species. they are divided by sir charles lyell into two divisions, the older pliocene and newer pliocene. the pliocene deposits of britain occur in suffolk, and are known by the name of "crags," this being a local term used for certain shelly sands, which are employed in agriculture. two of these crags are referable to the older pliocene, viz., the white and red crags,--and one belongs to the newer pliocene, viz., the norwich crag. the _white or coralline crag_ of suffolk is the oldest of the pliocene deposits of britain, and is an exceedingly local formation, occurring in but a single small area, and having a maximum thickness of not more than feet. it consists of soft sands, with occasional intercalations of flaggy limestone. though of small extent and thickness, the coralline crag is of importance from the number of fossils which it contains. the name "coralline" is a misnomer; since there are few true corals, and the so-called "corals" of the formation are really _polyzoa_, often of very singular forms. the shells of the coralline crag are mostly such as inhabit the seas of temperate regions; but there occur some forms usually looked upon as indicating a warm climate. the _upper_ or _red crag_ of suffolk--like the coralline crag--has a limited geographical extent and a small thickness, rarely exceeding feet. it consists of quartzose sands, usually deep red or brown in colour, and charged with numerous fossils. altogether more than species of shells are known from the red crag, of which per cent are referable to existing species. the shells indicate, upon the whole, a temperate or even cold climate, decidedly less warm than that indicated by the organic remains of the coralline crag. it appears, therefore, that a gradual refrigeration was going on during the pliocene period, commencing in the coralline crag, becoming intensified in the red crag, being still more severe in the norwich crag, and finally culminating in the arctic cold of the glacial period. besides the _mollusca_, the red crag contains the ear-bones of whales, the teeth of sharks and rays, and remains of the mastodon, rhinoceros, and tapir. the _newer pliocene_ deposits are represented in britain by the _norwich crag_, a local formation occurring near norwich. it consists of incoherent sands, loams, and gravels, resting in detached patches, from to feet in thickness, upon an eroded surface of chalk. the norwich crag contains a mixture of marine, land, and fresh-water shells, with remains of fishes and bones of mammals; so that it must have been deposited as a local sea-deposit near the mouth of an ancient river. it contains altogether more than marine shells, of which per cent belong to existing species. of the mammals, the two most important are an elephant (_elephas meridionalis_), and the characteristic pliocene mastodon (_m. arvernensis_), which is hitherto the only mastodon found in britain. according to the most recent views of high authorities, certain deposits--such as the so-called "bridlington crag" of yorkshire, and the "chillesford beds" of suffolk--are to be also included in the newer pliocene, upon the ground that they contain a small proportion of extinct shells. our knowledge, however, of the existing molluscan fauna, is still so far incomplete, that it may reasonably be doubted if these supposed extinct forms have actually made their final disappearance, whilst the strata in question have a strong natural connection with the "glacial deposits," as shown by the number of arctic mollusca which they contain. here, therefore, these beds will be included in the post-pliocene series, in spite of the fact that some of their species of shells are not known to exist at the present day. the following are the more important pliocene deposits which have been hitherto recognised out of britain:-- . in the neighbourhood of antwerp occur certain "crags," which are the equivalent of the white and red crag in part. the lowest of these contains less than per cent, and the highest per cent, of existing species of shells, the remainder being extinct. . bordering the chain of the apennines, in italy, on both sides is a series of low hills made up of tertiary strata, which are known as the sub-apennine beds. part of these is of miocene age, part is older pliocene, and a portion is newer pliocene. the older pliocene portion of the sub-apennines consists of blue or brown marls, which sometimes attain a thickness of feet. . in the valley of the arno, above florence, are both older and newer pliocene strata. the former consist of blue clays and lignites, with an abundance of plants. the latter consist of sands and conglomerates, with remains of large carnivorous mammals, mastodon, elephant, rhinoceros, hippopotamus, &c. . in sicily, newer pliocene strata are probably more largely developed than anywhere else in the world, rising sometimes to a height of feet above the sea. the series consists of clays, marls, sands, and conglomerates, capped by a compact limestone, which attains a thickness of from to feet. the fossils of these beds belong almost entirely to living species, one of the commonest being the great scallop of the mediterranean (_pecten jacoboeus_). . occupying an extensive area round the caspian, aral, and azof seas, are pliocene deposits known as the "aralo-caspian" beds. the fossils in these beds are partly freshwater, partly marine, and partly intermediate in character, and they are in great part identical with species now inhabiting the caspian. the entire formation appears to indicate the former existence of a great sheet of brackish water, forming an inland sea, like the caspian, but as large as, or larger than, the mediterranean. . in the united states, strata of pliocene age are found in north and south carolina. they consist of sands and clays, with numerous fossils, chiefly _molluscs_ and _echinoderms_. from to per cent of the fossils belong to existing species. on the loup fork of the river platte, in the upper missouri region, are strata which are also believed to be referable to the pliocene period, and probably to its upper division. they are from to feet thick, and contain land-shells, with the bones of numerous mammals, such as camels, rhinoceroses, mastodons, elephants, the horse, stag, &c. as regards the _life_ of the pliocene period, there are only two classes of organisms to which our attention need be directed--namely, the shell-fish and the mammals. so far as the former are concerned, we have to note in the first place that the introduction of new species of animals upon the globe went on rapidly during this period. in the older pliocene deposits, the number of shells of existing species is only from to per cent; but in the newer pliocene the proportion of living forms rises to as much as from to per cent. whilst the molluscs thus become rapidly modernised, the mammals still all belong to extinct species, though modern generic types gradually supersede the more antiquated forms of the miocene. in the second place, there is good evidence to show that the pliocene period was one in which the climate of the northern hemisphere underwent a gradual refrigeration. in the miocene period, there is evidence to show that europe possessed a climate very similar to that now enjoyed by the southern united states, and certainly very much warmer than it is at present. the presence of palm-trees upon the land, and of numerous large cowries, cones, and other shells of warm regions in the sea, sufficiently proves this. in the older pliocene deposits, on the other hand, northern forms predominate amongst the shells, though some of the types of hotter regions still survive. in the newer pliocene, again, the molluscs are such as almost exclusively inhabit the seas of temperate or even cold regions; whilst if we regard deposits like the "bridlington crag" and "chillesford beds" as truly referable to this period, we meet at the close of this period with shells such as nowadays are distinctively characteristic of high latitudes. it might be thought that the occurrence of quadrupeds such as the elephant, rhinoceros, and hippopotamus, would militate against this generalisation, and would rather support the view that the climate of europe and the united states must have been a hot one during the later portion of the pliocene period. we have, however, reason to believe that many of these extinct mammals were more abundantly furnished with hair, and more adapted to withstand a cool temperature, than any of their living congeners. we have also to recollect that many of these large herbivorous quadrupeds may have been, and indeed probably were, more or less migratory in their habits; and that whilst the winters of the later portion of the pliocene period were cold, the summers might have been very hot. this would allow of a northward migration of such terrestrial animals during the summer-time, when there would be an ample supply of food and a suitably high temperature, and a southward recession towards the approach of winter. the chief palæontological interests of the pliocene deposits, as of the succeeding post-pliocene, centre round the mammals of the period; and amongst the many forms of these we may restrict our attention to the orders of the hoofed quadrupeds (_ungulates_), the _proboscideans_, the _carnivora_, and the _quadrumana_. almost all the other mammalian orders are more or less fully represented in pliocene times, but none of them attains any special interest till we enter upon the post-pliocene. amongst the odd-toed ungulates, in addition to the remains of true tapirs (_tapirus arvernensis_), we meet with the bones of several species of rhinoceros, of which the _rhinoceros etruscus_ and _r. megarhinus_ (fig. ) are the most important. the former of these (fig. , a) derives its specific name from its abundance in the pliocene deposits of the val d'arno, near florence, and though principally pliocene in its distribution, it survived into the earlier portion of the post-pliocene period. _rhinoceros etruscus_ agreed with the existing african forms in having two horns placed one behind the other, the front one being the longest; but it was comparatively slight and slender in its build, whilst the nostrils were separated by an incomplete bony partition. in the _rhinoceros megarhinus_ (fig. , b), on the other hand, no such partition exists between the nostrils, and the nasal bones are greatly developed in size. it was a two-horned form, and is found associated with _elephas meridionalis_ and _e. antiquus_ in the pliocene deposits of the val d'arno, near florence. like the preceding, it survived, in diminished numbers, into the earlier portion of the post-pliocene period. [illustration: fig. .--a. under surface of the skull of _rhinoceros etruscus_, one-seventh of the natural size--pliocene, italy.; b, crowns of the three true molars of the upper jaw, left side, of _rhinoceros megarhinus_ (_r. leptorhinus_, falconer), one-half of the natural size--pliocene, france. (after falconer.)] the horses (_equidoe_) are represented, both in europe and america, by the three-toed hipparions, which survive from the miocene, but are now verging upon extinction. for the first time, also, we meet with genuine horses (_equus_), in which each foot is provided with a single complete toe only, encased in a single broad hoof. one of the american species of this period (the _equus excelsus_) quite equalled the modern horse in stature; and it is interesting to note the occurrence of indigenous horses in america at such a comparatively late geological epoch, seeing that this continent certainly possessed none of these animals when first discovered by the spaniards. amongst the even-toed ungulates, we may note the occurrence of swine (_suida_), of forms allied to the camels (_camelidoe_), and of various kinds of deer (_cervidoe_); but the most interesting pliocene mammal belonging to this section is the great _hippopotamus major_ of britain and europe. this well-known species is very closely allied to the living _hippopotamus amphibius_ of africa, from which it is separated only by its larger dimensions, and by certain points connected with the conformation of the skeleton. it is found very abundantly in the pliocene deposits of italy and france, associated with the remains of the elephant, mastodon, and rhinoceros, and it survived into the earlier portion of the post-pliocene period. during this last-mentioned period, it extended its range northwards, and is found associated with the reindeer, the bison, and other northern animals. from this fact it has been inferred, with great probability, that the _hippotamus major_ was furnished with a long coat of hair and fur, thus differing from its nearly hairless modern representative, and resembling its associates, the mammoth and the woolly rhinoceros. [illustration: fig. .--third milk-molar of the left side of the upper jaw of _mastodon arvernensis_, showing the grinding surface. pliocene.] passing on to the pliocene proboscideans, we find that the great _deinotheria_ of the miocene have now wholly disappeared, and the sole representatives of the order are mastodons and elephants. the most important member of the former group is the _mastodon arvernensis_ (fig. ), which ranged widely over southern europe and england, being generally associated with remains of the _elephas meridionalis, e. antiquus, rhinoceros megarhinus_, and _hippopotamus major_. the lower jaw seems to have been destitute of incisor teeth; but the upper incisors are developed into great tusks, which sometimes reach a length of nine feet, and which have the simple curvature of the tusks of the existing elephants. amongst the pliocene elephants the two most important are the _elephas meridionalis_ and the _elephas antiquus_. of these, the _elephas meridionalis_ (fig. ) is found abundantly in the pliocene deposits of southern europe and england, and also survived into the earlier portion of the post-pliocene period. its molar teeth are of the type of those of the existing african elephant, the spaces enclosed by the transverse enamel-plates being more or less lozenge-shaped, whilst the curvature of the tusks is simple. the _elephas antiquus_ (fig. ) is very generally associated with the preceding, and it survived to an even later stage of the post-pliocene period. the molar teeth are of the type of the existing indian elephant, with comparatively thin enamel-ridges, placed closer together than in the african type; whilst the tusks were nearly straight. [illustration: fig. .--molar tooth of _elephas meridionalis_, one-third of the natural size. pliocene and post-pliocene.] [illustration: fig. .--molar tooth of _elephas antiquus_, one-third of the natural size. pliocene and post-pliocene.] amongst the pliocene _carnivores_, we meet with true bears (_ursus arvernensis_), hyænas (such as _hyoena hipparionum_), and genuine lions (such as the _felis angustus_ of north america); but the most remarkable of the beasts of prey of this period is the great "sabre-toothed tiger" (_machairodus_), species of which existed in the earlier miocene, and survived to the later post-pliocene. in this remarkable form we are presented with perhaps the most highly carnivorous type of all known beasts of prey. not only are the jaws shorter in proportion even than those of the great cats of the present day, but the canine teeth (fig. ) are of enormous size, greatly flattened so as to assume the form of a poignard, and having their margins finely serrated. a part from the characters of the skull, the remainder of the skeleton, so far as known, exhibits proofs that the sabre-toothed tiger was extraordinarily muscular and powerful, and in the highest degree adapted for a life of rapine. species of _machairodus_ must have been as large as the existing lion; and the genus is not only european, but is represented both in south america and in india, so that the geographical range of these predaceous beasts must have been very extensive. [illustration: fig. .--a, skull of _machairodus cultridens_, without the lower jaw, reduced in size; b, canine tooth of the same, one-half the natural size. pliocene, france.] lastly, we may note that the pliocene deposits of europe have yielded the remains of monkeys (_quadrumana_), allied to the existing _semnopitheci_ and macaques. literature. the following list comprises a small selection of some of the more important and readily accessible works and memoirs relating to the tertiary rocks and their fossils. with few exceptions, foreign works relating to the tertiary strata of the continent of europe or their organic remains have been omitted:-- ( ) 'elements of geology.' lyell. ( ) 'students' elements of geology.' lyell. ( ) 'manual of palæontology.' owen. ( ) 'british fossil mammals and birds.' owen. ( ) 'traité de paléontologie.' pictet. ( ) 'cours elémentaire de paléontologie.' d'orbigny. ( ) "probable age of the london clay," &c.--'quart. journ. geol. soc.,' vol. iii. prestwich. ( ) 'structure and probable age of the bagshot sands'--ibid., vol. iii. prestwich. ( ) 'tertiary formations of the isle of wight'--ibid., vol. ii. prestwich. ( ) 'structure of the strata between the london clay and the chalk,' &c.--ibid., vols. vi., viii., and x. prestwich. ( ) 'correlation of the eocene tertiaries of england, france, and belgium'--ibid., vol. xxvii. prestwich. ( ) 'on the fluvio-marine formations of the isle of wight'--ibid., vol. ix. edward forbes. ( ) 'newer tertiary deposits of the sussex coast'--ibid., vol. xiii. godwin-austen. ( ) 'kainozoic formations of belgium'--ibid., vol. xxii. godwin-austen. ( ) 'tertiary strata of belgium and french flanders'--ibid., vol. viii. lyell. ( ) 'on tertiary leaf-beds in the isle of mull'--ibid., vol. vii. the duke of argyll. ( ) 'newer tertiaries of suffolk and their fauna'--ibid., vol. xxvi. ray lankester. ( ) 'lower london tertiaries of kent'--ibid., vol. xxii. whitaker. ( ) "guide to the geology of london"--'mem. geol. survey.' whitaker. ( ) 'memoirs of the geological survey of great britain.' ( ) 'introductory outline of the geology of the crag district' (supplement to crag mollusca, palæontographical society). s. v. wood, jun., and f. w. harmer. ( ) "tertiary fluvio-marine deposits of the isle of wight." edward forbes. edited by godwin-austen; with descriptions of the fossils by morris, salter, and rupert jones--'memoirs of the geological survey.' ( ) 'geological excursions round the isle of wight.' mantell. ( ) 'catalogue of british fossils.' morris. ( ) 'catalogue of fossils in the museum of practical geology.' etheridge. ( ) 'monograph of the crag polyzoa' (palæontographical society). busk. ( ) 'monograph of the tertiary brachiopoda' (ibid.) davidson. ( ) 'monograph of the tertiary malacostracous crustacea' (ibid.) bell. ( ) 'monograph of the tertiary corals' (ibid.) milne-edwards and haime. ( ) 'supplement to the tertiary corals' (ibid.) martin duncan. ( ) 'monograph of the eocene mollusca' (ibid.) fred. e. edwards. ( ) 'monograph of the eocene mollusca' (ibid.) searles v. wood. ( ) 'monograph of the crag mollusca' (ibid.) searles v. wood. ( ) 'monograph of the tertiary entomostraca' (ibid.) rupert jones. ( ) 'monograph of the foraminifera of the crag' (ibid.) rupert jones, parker, and h. b. brady. ( ) 'monograph of the radiaria of the london clay' (ibid.) edward forbes. ( ) 'monograph of the cetacea of the red crag' (ibid.) owen. ( ) 'monograph of the fossil reptiles of the london clay' (ibid.) owen and bell. ( ) "on the skull of a dentigerous bird from the london clay of sheppey"--'quart. journ. geol. soc.,' vol. xxix. owen. ( ) 'ossemens fossiles.' cuvier. ( ) 'fauna antiqua sivalensis.' falconer and sir proby cautley. ( ) 'palæontological memoirs.' falconer. ( ) 'animaux fossiles et géologie de l'attique.' gaudry. ( ) "principal characters of the dinocerata"--'american journ. of science and arts,' vol. xi. marsh. ( ) 'principal characters of the brontotheridæ' (ibid.) marsh. ( ) 'principal characters of the tillodontia' (ibid.) marsh. ( ) "extinct vertebrata of the eocene of wyoming"--'geological survey of montana,' &c., . cope. ( ) "ancient fauna of nebraska"--'smithsonian contributions to knowledge,' vol. vi. leidy. ( ) 'manual of geology.' dana. ( ) "palæontology and evolution" (presidential address to the geological society of london, )--'quart. journ. geol. soc.,' vol. xxvi. huxley.' ( ) 'mineral conchology.' sowerby. ( ) 'description des coquilles fossiles,' &c. deshayes. ( ) 'description des coquilles tertiaires de belgique.' nyst. ( ) 'fossilen polypen des wiener tertiär-beckens.' reuss. ( ) 'palæontologische studien über die älteren tertiär-schichten der alpen.' reuss. ( ) 'land und süss-wasser conchylien der vorwelt.' sandberger. ( ) 'flora tertiaria helvetica.' heer. ( ) 'flora fossilis arctica.' heer. ( ) 'recherches sur le climat et la végétation du pays tertiaire.' heer. ( ) 'fossil flora of great britain.' lindley and hutton. ( ) 'fossil fruits and seeds of the london clay.' bowerbank. ( ) "tertiary leaf-beds of the isle of mull"--'quart. journ. geol. soc.,' vol. vii. edward forbes. ( ) 'the geology of england and wales.' horace b. woodward.[ ] [footnote : this work--published whilst these sheets were going through the press--gives to the student a detailed view of all the strata of england and wales, with their various sub-divisions, from the base of the palæozoic to the top of the tertiary.] chapter xxi. the quaternary period. the post-pliocene period. later than any of the tertiary formations are various detached and more or less superficial accumulations, which are generally spoken of as the _post-tertiary formations_, in accordance with the nomenclature of sir charles lyell--or as the _quaternary formations_, in accordance with the general usage of continental geologists. in all these formations we meet with no _mollusca_ except such as are now alive--with the partial and very limited exception of some of the oldest deposits of this period, in which a few of the shells occasionally belong to species not known to be in existence at the present day. whilst the _shell-fish_ of the quaternary deposits are, generally speaking, identical with existing forms, the _mammals_ are sometimes referable to living, sometimes to extinct species. in accordance with this, the quaternary formations are divided into two groups: ( ) the _post-pliocene_, in which the shells are almost invariably referable to existing species, but some of the _mammals are extinct_; and ( ) the _recent_, in which _the shells and the mammals alike belong to existing species_. the post-pliocene deposits are often spoken of as the pleistocene formations (gr. _pleistos_, most; _kainos_, new or recent), in allusion to the fact that the great majority of the living beings of this period belong to the species characteristic of the "new" or recent period. the _recent_ deposits, though of the highest possible interest, do not properly concern the palæontologist strictly so-called, but the zoologist, since they contain the remains of none but existing animals. they are "pre-historic," but they belong entirely to the existing terrestrial order. the _post-pliocene_ deposits, on the other hand, contain the remains of various extinct mammals; and though man undoubtedly existed in, at any rate, the later portion of this period, if not throughout the whole of it, they properly form part of the domain of the palæontologist. the post-pliocene deposits are extremely varied, and very widely distributed; and owing to the mode of their occurrence, the ordinary geological tests of age are in their case but very partially available. the subject of the classification of these deposits is therefore an extremely complicated one; and as regards the age of even some of the most important of them, there still exists considerable difference of opinion. for our present purpose, it will be convenient to adopt a classification of the post-pliocene deposits founded on the relations which they bear in time to the great "ice-age" or "glacial period;" though it is not pretended that our present knowledge is sufficient to render such a classification more than a provisional one. in the early tertiary period, as we have seen, the climate of the northern hemisphere, as shown by the eocene animals and plants, was very much hotter than it is at present--partaking, indeed, of a sub-tropical character. in the middle tertiary or miocene period, the temperature, though not so high, was still much warmer than that now enjoyed by the northern hemisphere; and we know that the plants of temperate regions at this time flourished within the arctic circle. in the later tertiary or pliocene period, again, there is evidence that the northern hemisphere underwent a further progressive diminution of temperature; though the climate of europe generally seems at the close of the tertiary period to have been if anything warmer, or at any rate not colder, than it is at the present day. with the commencement of the quaternary period, however, this diminution of temperature became more decided; and beginning with a temperate climate, we find the greater portion of the northern hemisphere to become gradually subjected to all the rigours of intense arctic cold. all the mountainous regions of northern and central europe, of britain, and of north america, became the nurseries of huge ice-streams, and large areas of the land appear to have been covered with a continuous ice-sheet. the arctic conditions of this, the well-known "glacial period," relaxed more than once, and were more than once re-established with lesser intensity. finally, a gradual but steadily progressive amelioration of temperature took place; the ice slowly gave way, and ultimately disappeared altogether; and the climate once more became temperate, except in high northern latitudes. the changes of temperature sketched out above took place slowly and gradually, and occupied the whole of the post-pliocene period. in each of the three periods marked out by these changes--in the early temperate, the central cold, and the later temperate period--certain deposits were laid down over the surface of the northern hemisphere; and these deposits collectively constitute the post-pliocene formations. hence we may conveniently classify all the accumulations of this age under the heads of ( ) _pre-glacial_ deposits, ( ) _glacial_ deposits, and ( ) _post-glacial_ deposits, according as they were formed before, during, or after the "glacial period." it cannot by any means be asserted that we can definitely fix the precise relations in time of all the post-pliocene deposits to the glacial period. on the contrary, there are some which hold a very disputed position as regards this point; and there are others which do not admit of definite allocation in this manner at all, in consequence of their occurrence in regions where no "glacial period" is known to have been established. for our present purpose, however, dealing as we shall have to do principally with the northern hemisphere, the above classification, with all its defects, has greater advantages than any other that has been yet proposed. i. pre-glacial deposits.--the chief pre-glacial deposit of britain is found on the norfolk coast, reposing upon the newer pliocene (norwich crag), and consists of an ancient land-surface which is known as the "cromer forest-bed." this consists of an ancient soil, having embedded in it the stumps of many trees, still in an erect position, with remains of living plants, and the bones of recent and extinct quadrupeds. it is overlaid by fresh-water and marine beds, all the shells of which belong to existing species, and it is finally surmounted by true "glacial drift." while all the shells and plants of the cromer forest-bed and its associated strata belong to existing species, the mammals are partly living, partly extinct. thus we find the existing wolf (_canis lupus_), red deer (_cervus elaphus_), roebuck (_cervus capreolus_), mole (_talpa europtoea_), and beaver (_castor fiber_), living in western england side by side with the _hippopotamus major, elephas antiquus, elephas meridionalis, rhinoceros etruscus_, and _r. megarhinus_ of the pliocene period, which are not only extinct, but imply an at any rate moderately warm climate. besides the above, the forest-bed has yielded the remains of several extinct species of deer, of the great extinct beaver (_trogontherium cuvieri_), of the caledonian bull or "urus" (_bos primigenius_), and of a horse (_equus fossilis_), little if at all distinguishable from the existing form. the so-called "bridlington crag" of yorkshire, and the "chillesford beds" of suffolk, are probably to be regarded as also belonging to this period; though many of the shells which they contain are of an arctic character, and would indicate that they were deposited in the commencement of the glacial period itself. owing, however, to the fact that a few of the shells of these deposits are not known to occur in a living condition, these, and some other similar accumulations, are sometimes considered as referable to the pliocene period. ii. glacial deposits.--under this head is included a great series of deposits which are widely spread over both europe and america, and which were formed at a time when the climate of these countries was very much colder than it is at present, and approached more or less closely to what we see at the present day in the arctic regions. these deposits are known by the general name of the _glacial deposits_, or by the more specialised names of the drift, the northern drift, the boulder-clay, the till, &c. these glacial deposits are found in britain as far south as the thames, over the whole of northern europe, in all the more elevated portions of southern and central europe, and over the whole of north america, as far south as the th parallel. they generally occur as sands, clays, and gravels, spread in widely-extended sheets over all the geological formations alike, except the most recent, and are commonly spoken of under the general term of "glacial drift." they vary much in their exact nature in different districts, but they universally consist of one, or all, of the following members:-- . _unstratified_ clays, or loams, containing numerous angular or sub-angular blocks of stone, which have often been transported for a greater or less distance from their parent rock, and which often exhibit polished, grooved, or striated surfaces. these beds are what is called _boulder-clay_, or _till_. . sands, gravels, and clays, often more or less regularly _stratified_, but containing erratic blocks, often of large size, and with their edges _unworn_, derived from considerable distances from the place where they are now found. in these beds it is not at all uncommon to find fossil shells; and these, though of existing species, are generally of an arctic character, comprising a greater or less number of forms which are now exclusively found in the icy waters of the arctic seas. these beds are often spoken of as "stratified drift." . _stratified_ sands and gravels, in which the pebbles are _worn_ and rounded, and which have been produced by a rearrangement of ordinary glacial beds by the sea. these beds are commonly known as "drift-gravels," or "regenerated drift". some of the last-mentioned of these are doubtless post-glacial; but, in the absence of fossils, it is often impossible to arrive at a positive opinion as to the precise age of superficial accumulations of this nature. it is also the opinion of high authorities that a considerable number of the so-called "cave-deposits," with the bones of extinct mammals, truly belong to the glacial period, being formed during warm intervals when the severity of the arctic cold had become relaxed. it is further believed that some, at any rate, of the so-called "high-level" river-gravels and "brick-earths" have likewise been deposited during mild or warm intervals in the great age of ice; and in two or three instances this has apparently been demonstrated--deposits of this nature, with the bones of extinct animals and the implements of man, having been shown to be overlaid by true boulder-clay. the fossils of the undoubted glacial deposits are principally shells, which are found in great numbers in certain localities, sometimes with _foraminifera_, the bivalved cases of ostracode crustaceans, &c. whilst some of the shells of the "drift" are such as now live in the seas of temperate regions, others, as previously remarked, are such as are now only known to live in the seas of high latitudes; and these therefore afford unquestionable evidence of cold conditions. amongst these arctic forms of shells which characterise the glacial beds may be mentioned _pecten islandicus_ (fig. ), _pecten groenlandicus, scalaria groenlandica, leda truncata, astarte borealis, tellina proxima, nattra clausa_, &c. [illustration: fig. .--left valve of _pecten islandicus_, glacial and recent.] iii. post-glacial deposits.--as the intense cold of the glacial period became gradually mitigated, and temperate conditions of climate were once more re-established, various deposits were formed in the northern hemisphere, which are found to contain the remains of extinct mammals, and which, therefore, are clearly of post-pliocene age. to these deposits the general name of _post-glacial_ formations is given; but it is obvious that, from the nature of the case, and with our present limited knowledge, we cannot draw a rigid line of demarcation between the deposits formed towards the close of the glacial period, or during warm "interglacial" periods, and those laid down after the ice had fairly disappeared. indeed it is extremely improbable that any such rigid line of demarcation should ever have existed; and it is far more likely that the glacial and post-glacial periods, and their corresponding deposits, shade into one another by an imperceptible gradation. accepting this reservation, we may group together, under the general head of "post-glacial deposits," most of the so-called "valley-gravels," "brick-earths," and "cave-deposits," together with some "raised beaches" and various deposits of peat. though not strictly within the compass of this work, a few words may be said here as to the origin and mode of formation of the brick-earths, valley-gravels, and cave-deposits, as the subject will thus be rendered more clearly intelligible. every river produces at the present day beds of fine mud and loam, and accumulations of gravel, which it deposits at various parts of its course--the gravel generally occupying the lowest position, and the finer sands and mud coming above. numerous deposits of a similar nature are found in most countries in various localities, and at various heights above the present channels of our rivers. many of these fluviatile (lat. _fluvius_, a river) deposits consist of fine loam, worked for brick-making, and known as "brick-earths;" and they have yielded the remains of numerous extinct mammals, of which the mammoth (_elephas primigenius_) is the most abundant. in the valley of the rhine these fluviatile loams (known as "loess") attain a thickness of several hundred feet, and contain land and fresh-water shells of existing species. with these occur the remains of mammals, such as the mammoth and woolly rhinoceros. many of these brick-earths are undoubtedly post-glacial, but others seem to be clearly "inter-glacial;" and instances have recently been brought forward in which deposits of brick-earth containing bones and shells of fresh-water molluscs have been found to be overlaid by regular unstratified boulder-clay. the so-called "valley-gravels," like the brick-earths, are fluviatile deposits, but are of a coarser nature, consisting of sands and gravels. every river gives origin to deposits of this kind at different points along the course of its valley; and it is not uncommon to find that there exist in the valley of a single river two or more sets of these gravel-beds, formed by the river itself, but formed at times when the river ran at different levels, and therefore formed at different periods. these different accumulations are known as the "high-level" and "low-level" gravels; and a reference to the accompanying diagram will explain the origin and nature of these deposits (fig. ). when a river begins to occupy a particular line of drainage, and to form its own channel, it will deposit fluviatile sands and gravels along its sides. as it goes on deepening the bed or valley through which it flows, it will deposit other fluviatile strata at a lower level beside its new bed. in this way have arisen the terms "high-level" and "low-level" gravels. we find, for instance, a modern river flowing through a valley which it has to a great extent or entirely formed itself; by the side of its immediate channel we may find gravels, sand, and loam (fig. , ') deposited by the river flowing in its present bed. these are _recent_ fluviatile or alluvial deposits. at some distance from the present bed of the river, and at a higher level, we may find other sands and gravels, quite like the recent ones in character and origin, but formed at a time when the stream flowed at a higher level, and before it had excavated its valley to its present depth. these (fig. , ') are the so-called "_low-level_ gravels" of a river. at a still higher level, and still farther removed from the present bed of the river, we may find another terrace, composed of just the same materials as the lower one, but formed at a still earlier period, when the excavation of the valley had proceeded to a much less extent. these (fig. , ') are the so-called "_high-level_ gravels" of a river, and there may be one or more terraces of these. [illustration: fig. .--recent and post-pliocene alluvial deposits. , peat of the recent period; , gravel of the modern river: ', loam of the modern river; . lower-level valley-gravel with bones of extinct mammals (post-pliocene); ', loam of the same age as ; . higher-level valley-gravel (post-pliocene); ', loam of the same age as ; . upland gravels of various kinds (often glacial drift); , older rock. (after sir charles lyell.)] the important fact to remember about these fluviatile deposits is this--that here the ordinary geological rule is reversed. the high-level gravels are, of course, the highest, so far as their actual elevation above the sea is concerned; but geologically the lowest, since they are obviously much older than the low-level gravels, as these are than the recent gravels. how much older the high-level gravels may be than the low-level ones, it is impossible to say. they occur at heights varying from to feet above the present river-channels, and they are therefore older than the recent gravels by the time required by the river to dig out its own bed to this depth. how long this period may be, our data do not enable us to determine accurately; but if we are to calculate from the observed rate of erosion of the actually existing rivers, the period between the different valley-gravels must be a very long one. the lowest or recent fluviatile deposits which occur beside the bed of the present river, are referable to the recent period, as they contain the remains of none but living mammals. the two other sets of gravels are post-pliocene, as they contain the bones of extinct mammals, mixed with land and fresh-water shells of existing species. among the more important extinct mammals of the low-level and high-level valley-gravels may be mentioned the _elephas antiquus_, the mammoth (_elephas primigenius_), the woolly rhinoceros (_r. tichorhinus_), the hippopotamus, the cave-lion, and the cave-bear. along with these are found unquestionable traces of the existence of man, in the form of rude flint implements of undoubted human workmanship. the so-called "cave-deposits," again, though exhibiting peculiarities due to the fact of their occurrence in caverns or fissures in the rocks, are in many respects essentially similar to the older valley-gravels. caves, in the great majority of instances, occur in limestone. when this is not the case, it will generally be found that they occur along lines of sea-coast, or along lines which can be shown to have anciently formed the coast-line. there are many caves, however, in the making of which it can be shown that the sea has had no hand; and these are most of the caves of limestone districts. these owe their origin to the solvent action upon lime of water holding carbonic acid in solution. the rain which falls upon a limestone district absorbs a certain amount of carbonic acid from the air, or from the soil. it then percolates through the rock, generally along the lines of jointing so characteristic of limestones, and in its progress it dissolves and carries off a certain quantity of carbonate of lime. in this way, the natural joints and fissures in the rock are widened, as can be seen at the present day in any or all limestone districts. by a continuance of this action for a sufficient length of time, caves may ultimately be produced. nothing, also, is commoner in a limestone district than for the natural drainage to take the line of some fissure, dissolving the rock in its course. in this way we constantly meet in limestone districts with springs issuing from the limestone rock--sometimes as large rivers--the waters of which are charged with carbonate of lime, obtained by the solution of the sides of the fissure through which the waters have flowed. by these and similar actions, every district in which limestones are extensively developed will be found to exhibit a number of natural caves, rents, or fissures. the first element, therefore, in the production of cave-deposits, is the existence of a period in which limestone rocks were largely dissolved, and caves were formed in consequence of the then existing drainage taking the line of some fissure. secondly, there must have been a period in which various deposits were accumulated in the caves thus formed. these cavern-deposits are of very various nature, consisting of mud, loam, gravel, or breccias of different kinds. in all cases, these materials have been introduced into the cave at some period subsequent to, or contemporaneous with, the formation of the cave. sometimes the cave communicates with the surface by a fissure through which sand, gravel, &c., may be washed by rains or by floods from some neighbouring river. sometimes the cave has been the bed of an ancient stream, and the deposits have been formed as are fluviatile deposits at the surface. or, again, the river has formerly flowed at a greater elevation than it does at present, and the cave has been filled with fluviatile deposits by the river at a time prior to the excavation of its bed to the present depth (fig. ). in this last case, the cave-deposits obviously bear exactly the same relation in point of antiquity to recent deposits, as do the low-level and high-level valley-gravels to recent river-gravels. in any case, it is necessary for the physical geography of the district to change to some extent, in order that the cave-deposits should be preserved. if the materials have been introduced by a fissure, the cave will probably become ultimately filled to the roof, and the aperture of admission thus blocked up. if a river has flowed through the cave, the surface configuration of the district must be altered so far as to divert the river into a new channel. and if the cave is placed in the side of a river-valley, as in fig. , the river must have excavated its channel to such a depth that it can no longer wash out the contents of the cave even in high floods. [illustration: fig .--diagrammatic section across a river-valley and cave. _a a_, recent valley-gravels near the channel (b) of the existing river; c, cavern, partly filled with cave-earth; _d d_, high-level gravels, filling fissures in the limestone, which perhaps communicate in some instances with the cave, and form a channel by which materials of various kinds were introduced into it; _e e_, inclined beds of limestone.] if the cave be entirely filled, the included deposits generally get more or less completely cemented together by the percolation through them of water holding carbonate of lime in solution. if the cave is only partially filled, the dropping of water from the roof holding lime in solution, and its subsequent evaporation, would lead to the formation over the deposits below of a layer of stalagmite, perhaps several inches, or even feet, in thickness. in this way cave-deposits, with their contained remains, may be hermetically sealed up and preserved without injury for an altogether indefinite period of time. in all caves in limestone in which deposits containing bones are found, we have then evidence of three principal sets of changes. ( .) a period during which the cave was slowly hollowed out by the percolation of acidulated water; ( .) a period in which the cave became the channel of an engulfed river, or otherwise came to form part of the general drainage-system of the district; ( .) a period in which the cave was inhabited by various animals. as a typical example of a cave with fossiliferous post-pliocene deposits, we may take kent's cavern, near torquay, in which a systematic and careful examination has revealed the following sequence of accumulations in descending order:-- (a) large blocks of limestone, which lie on the floor of the cave, having fallen from the roof, and which are sometimes cemented together by stalagmite. (b) a layer of black mould, from three to twelve inches thick, with human bones, fragments of pottery, stone and bronze implements, and the bones of animals now living in britain. this, therefore, is a _recent_ deposit. (c) a layer of stalagmite, from sixteen to twenty inches thick, but sometimes as much as five feet, containing the bones of man, together with those of extinct post-pliocene mammals. (d) a bed of red cave-earth, sometimes four feet in thickness, with numerous bones of extinct mammals (mammoth, cave-bear, &c.), together with human implements of flint and horn. (e) a second bed of stalagmite, in places twelve feet in thickness, with bones of the cave-bear. (f) a red-loam and cave-breccia, with remains of the cave-bear and human implements. the most important mammals which are found in cave-deposits in europe generally, are the cave-bear, the cave-lion, the cave-hyæna, the reindeer, the musk-ox, the glutton, and the lemming--of which the first three are probably identical with existing forms, and the remainder are certainly so--together with the mammoth and the woolly rhinoceros, which are undoubtedly extinct. along with these are found the implements, and in some cases the bones, of man himself, in such a manner as to render it absolutely certain that an early race of men was truly contemporaneous in western europe with the animals above mentioned. iv. unclassified post-pliocene deposits.--apart from any of the afore mentioned deposits, there occur other accumulations--sometimes superficial, sometimes in caves--which are found in regions where a "glacial period" has not been fully demonstrated, or where such did not take place; and which, therefore, are not amenable to the above classification. the most important of these are known to occur in south america and australia; and though their numerous extinct mammalia place their reference to the post-pliocene period beyond doubt, their relations to the glacial period and its deposits in the northern hemisphere have not been precisely determined. chapter xxii. the post-pliocene period--_continued_. as regards the _life_ of the post-pliocene period, we have, in the first place, to notice the effect produced throughout the northern hemisphere by the gradual supervention of the glacial period. previous to this the climate must have been temperate or warm-temperate; but as the cold gradually came on, two results were produced as regards the living beings of the area thus affected. in the first place, all those mammals which, like the mammoth, the woolly rhinoceros, the lion, the hyæna, and the hippopotamus, require, at any rate, moderately warm conditions, would be forced to migrate southwards to regions not affected by the new state of things. in the second place, mammals previously inhabiting higher latitudes, such as the reindeer, the musk-ox, and the lemming, would be enabled by the increasing cold to migrate southwards, and to invade provinces previously occupied by the elephant and the rhinoceros. a precisely similar, but more slowly-executed process, must have taken place in the sea, the northern mollusca moving southwards as the arctic conditions of the glacial period became established, whilst the forms proper to temperate seas receded. as regards the readily locomotive mammals, also, it is probable that this process was carried on repeatedly in a partial manner, the southern and northern forms alternately fluctuating backwards and forwards over the same area, in accordance with the fluctuations of temperature which have been shown by mr james geikie to have characterised the glacial period as a whole. we can thus readily account for the intermixture which is sometimes found of northern and southern types of mammalia in the same deposits, or in deposits apparently synchronous, and within a single district. lastly, at the final close of the arctic cold of the glacial period, and the re-establishment of temperate conditions over the northern hemisphere, a reversal of the original process took place--the northern mammals retiring within their ancient limits, and the southern forms pressing northwards and reoccupying their original domains. the _invertebrate_ animals of the post-pliocene deposits require no further mention--all the known forms, except a few of the shells in the lowest beds of the formation, being identical with species now in existence upon the globe. the only point of importance in this connection has been previously noticed--namely, that in the true glacial deposits themselves a considerable number of the shells belong to northern or arctic types. as regards the _vertebrate_ animals of the period, no extinct forms of fishes, amphibians, or reptiles are known to occur, but we meet with both extinct birds and extinct mammals. the remains of the former are of great interest, as indicating the existence during post-pliocene times, at widely remote points of the southern hemisphere, of various wingless, and for the most part gigantic, birds. all the great wingless birds of the order _cursores_ which are known as existing at the present day upon the globe, are restricted to regions which are either wholly or in great part south of the equator. thus the true ostriches are african; the rheas are south american; the emeus are australian; the cassowaries are confined to northern australia, papua, and the indian archipelago; the species of _apteryx_ are natives of new zealand; and the dodo and solitaire (wingless, though probably not true _cursores_), both of which have been exterminated within historical times, were inhabitants of the islands of mauritius and rodriguez, in the indian ocean. in view of these facts, it is noteworthy that, so far as known, all the cursorial birds of the post-pliocene period should have been confined to the same hemisphere as that inhabited by the living representatives of the order. it is still further interesting to notice that the extinct forms in question are only found in geographical provinces which are now, or have been within historical times, inhabited by similar types. the greater number of the remains of these have been discovered in new zealand, where there now live several species of the curious wingless genus _apteryx_; and they have been referred by professor owen to several generic groups, of which _dinornis_ is the most important (fig. ). fourteen species of _dinornis_ have been described by the distinguished palæontologist just mentioned, all of them being large wingless birds of the type of the existing ostrich, having enormously powerful hind-limbs adapted for running, but with the wings wholly rudimentary, and the breast-bone devoid of the keel or ridge which characterises this bone in all birds which fly. the largest species is the _dinornis giganteus_, one of the most gigantic of living or fossil birds, the shank (tibia) measuring a yard in length, and the total height being at least ten feet. another species, the _dinornis elephantopus_ (fig. ), though not standing more than about six feet in height, was of an even more ponderous construction--"the framework of the skeleton being the most massive of any in the whole class of birds," whilst "the toe-bones almost rival those of the elephant" (owen). the feet in _dinornis_ were furnished with three toes, and are of interest as presenting us with an undoubted bird big enough to produce the largest of the foot-prints of the triassic sandstones of connecticut. new zealand has now been so far explored, that it seems questionable if it can retain in its recesses any living example of _dinornis_; but it is certain that species of this genus were alive during the human period, and survived up to quite a recent date. not only are the bones very numerous in certain localities, but they are found in the most recent and superficial deposits, and they still contain a considerable proportion of animal matter; whilst in some instances bones have been found with the feathers attached, or with the horny skin of the legs still adhering to them. charred bones have been found in connection with native "ovens;" and the traditions of the maories contain circumstantial accounts of gigantic wingless birds, the "moas," which were hunted both for their flesh and their plumage. upon the whole, therefore, there can be no doubt but that the moas of new zealand have been exterminated at quite a recent period--perhaps within the last century--by the unrelenting pursuit of man,--a pursuit which their wingless condition rendered them unable to evade. [illustration: fig. .--skeleton of _dinornis elephantopus_, greatly reduced. post-pliocene, new zealand. (after owen.)] in madagascar, bones have been discovered of another huge wingless bird, which must have been as large as, or larger than, the _dinornis giganteus_, and which has been described under the name of _Æpiornis maximus_. with the bones have been found eggs measuring from thirteen to fourteen inches in diameter, and computed to have the capacity of three ostrich eggs. at least two other smaller species of _Æpiornis_ have been described by grandidier and milne-edwards as occurring in madagascar; and they consider the genus to be so closely allied to the _dinornis_ of new zealand, as to prove that these regions, now so remote, were at one time united by land. unlike new zealand, where there is the _apteryx_, madagascar is not known to possess any living wingless birds; but in the neighbouring island of mauritius the wingless dodo (_didus ineptus_) has been exterminated less than three hundred years ago; and the little island of rodriguez, in the same geographical province, has in a similar period lost the equally wingless solitaire (_pezophaps_), both of these, however, being generally referred to the _rasores_. the _mammals_ of the post-pliocene period are so numerous, that in spite of the many points of interest which they present, only a few of the more important forms can be noticed here, and that but briefly. the first order that claims our attention is that of the _marsupials_, the headquarters of which at the present day is the australian province. in oolitic times europe possessed its small marsupials, and similar forms existed in the same area in the eocene and miocene periods; but if size be any criterion, the culminating point in the history of the order was attained during the post-pliocene period in australia. from deposits of this age there has been disentombed a whole series of remains of extinct, and for the most part gigantic, examples of this group of quadrupeds. not to speak of wombats and phalangers, two forms stand out prominently as representatives of the post-pliocene animals of australia. one of these is _diprotodon_ (fig. ), representing, with many differences, the well-known modern group of the kangaroos. in its teeth, _diprotodon_ shows itself to be closely allied to the living, grass-eating kangaroos; but the hind-limbs were not so disproportionately long. in size, also, _diprotodon_ must have many times exceeded the dimensions of the largest of its living successors, since the skull measures no less than three feet in length. the other form in question is _thylacoleo_ (fig. ), which is believed by professor owen to belong to the same group as the existing "native devil" (_dasyurus_) of van diemen's land, and therefore to have been flesh-eating and rapacious in its habits, though this view is not accepted by others. the principal feature in the skull of _thylacoleo_ is the presence, on each side of each jaw, of a single huge tooth, which is greatly compressed, and has a cutting edge. this tooth is regarded by owen as corresponding to the great cutting tooth of the jaw of the typical carnivores, but professor flower considers that _thylacoleo_ is rather related to the kangaroo-rats. the size of the crown of the tooth in question is not less than two inches and a quarter; and whether carnivorous or not, it indicates an animal of a size exceeding that of the largest of existing lions. [illustration: fig. .--skull of _diprotodon australis_, greatly reduced. post-pliocene, australia.] [illustration: fig. .--skull of _thylacoleo_. post-pliocene, australia. greatly reduced. (after flower.)] the order of the _edentates_, comprising the existing sloths, ant-eaters, and armadillos, and entirely restricted at the present day to south america, southern asia, and africa, is one alike singular for the limited geographical range of its members, their curious habits of life, and the well-marked peculiarities of their anatomical structure. south america is the metropolis of the existing forms; and it is an interesting fact that there flourished within post-pliocene times in this continent, and to some extent in north america also, a marvellous group of extinct edentates, representing the living sloths and armadillos, but of gigantic size. the most celebrated of these is the huge _megatherium cuvieri_ (fig. ) of the south american pampas. the megathere was a colossal sloth-like animal which attained a length of from twelve to eighteen feet, with bones more massive than those of the elephant. thus the thigh-bone is nearly thrice the thickness of the same bone in the largest of existing elephants, its circumference at its narrowest point nearly equalling its total length; the massive bones of the shank (tibia and fibula) are amalgamated at their extremities; the heel-bone (calcaneum) is nearly half a yard in length; the haunch-bones (ilia) are from four to five feet across at their crests; and the bodies of the vertebræ at the root of the tail are from five to seven inches in diameter, from which it has been computed that the circumference of the tail at this part might have been from five to six feet. the length of the fore-foot is about a yard, and the toes are armed with powerful curved claws. it is known now that the megathere, in spite of its enormous weight and ponderous construction, walked, like the existing ant-eaters and sloths, upon the outside edge of the fore-feet, with the claws more or less bent inwards towards the palm of the hand. as in the great majority of the edentate order, incisor and canine teeth are entirely wanting, the front of the jaws being toothless. the jaws, however, are furnished with five upper and four lower molar teeth on each side. these grinding teeth are from seven to eight inches in length, in the form of four-sided prisms, the crowns of which are provided with well-marked transverse ridges; and they continue to grow during the whole life of the animal. there are indications that the snout was prolonged, and more or less flexible; and the tongue was probably prehensile. from the characters of the molar teeth it is certain that the megathere was purely herbivorous in its habits; and from the enormous size and weight of the body, it is equally certain that it could not have imitated its modern allies, the sloths, in the feat of climbing, back downwards, amongst the trees. it is clear, therefore, that the megathere sought its sustenance upon the ground; and it was originally supposed to have lived upon roots. by a masterly piece of deductive reasoning, however, professor owen showed that this great "ground-sloth" must have truly lived upon the foliage of trees, like the existing sloths--but with this difference, that instead of climbing amongst the branches, it actually uprooted the tree bodily. in this _tour de force_, the animal sat upon its huge haunches and mighty tail, as on a tripod, and then grasping the trunk with its powerful arms, either wrenched it up by the roots or broke it short off above the ground. marvellous as this may seem, it can be shown that every detail in the skeleton of the megathere accords with the supposition that it obtained its food in this way. similar habits were followed by the allied _mylodon_ (fig. ), another of the great "ground-sloths," which inhabited south america during the post-pliocene period. in most respects, the _mylodon_ is very like the megathere; but the crowns of the molar teeth are flat instead of being ridged. the nearly-related genus _megalonyx_, unlike the megathere, but like the mylodon, extended its range northwards as far as the united states. [illustration: fig. .--_megatherium cuvieri_. post-pliocene, south america.] just as the sloths of the present day were formerly represented in the same geographical area by the gigantic megatheroids, so the little banded and cuirassed armadillos of south america were formerly represented by gigantic species, constituting the genus _glyptodon_. the _glyptodons_ (fig. ) differed from the living armadillos in having no bands in their armour, so that they must have been unable to roll themselves up. it is rare at the present day to meet with any armadillo over two or three feet in length; but the length of the _glyptodon clavipes_, from the tip of the snout to the end of the tail, was more than nine feet. [illustration: fig. .--skeleton of _mylodon robustus_. post-pliocene, south america.] [illustration: fig. .--skeleton of _glyptodon clavipes_. post-pliocene, south america.] there are no canine or incisor teeth in the _glyptodon_, but there are eight molars on each side of each jaw, and the crowns of these are fluted and almost trilobed. the head is covered by a helmet of bony plates, and the trunk was defended by an armour of almost hexagonal bony pieces united by sutures, and exhibiting special patterns of sculpturing in each species. the tail was also defended by a similar armour, and the vertebræ were mostly fused together so as to form a cylindrical bony rod. in addition to the above-mentioned forms, a number of other edentate animals have been discovered by the researches of m. lund in the post-pliocene deposits of the brazilian bone-caves. amongst these are true ant-eaters, armadillos, and sloths, many of them of gigantic size, and all specifically or generically distinct from existing forms. passing over the aquatic orders of the _sirenians_ and _cetaceans_, we come next to the great group of the hoofed quadrupeds, the remains of which are very abundant in post-pliocene deposits both in europe and north america. amongst the odd-toed ungulates the most important are the rhinoceroses, of which three species are known to have existed in europe during the post-pliocene period. two of these are the well-known pliocene forms, the _rhinoceros etruscus_ and the _r. megarhinus_ still surviving in diminished numbers; but the most famous is the _rhinoceros tichorhinus_ (fig. ), or so-called "woolly rhinoceros." this species is known not only by innumerable bones, but also by a carcass, at the time of its discovery complete, which was found embedded in the frozen soil of siberia towards the close of last century, and which was partly saved from destruction by the exertions of the naturalist pallas. from this, we know that the tichorhine rhinoceros, like its associate the mammoth, was provided with a coating of hair, and therefore was enabled to endure a more severe climate than any existing species. the skin was not thrown into the folds which characterise most of the existing forms; and the technical name of the species refers to the fact that the nostrils were completely separated by a bony partition. the head carried two horns, placed one behind the other, the front one being unusually large. as regards its geographical range, the woolly rhinoceros is found in europe in vast numbers north of the alps and pyrenees, and it also abounded in siberia; so that it would appear to be a distinctly northern form, and to have been adapted for a temperate climate. it is not known to occur in pliocene deposits, but it makes its first appearance in the pre-glacial deposits, surviving the glacial period, and being found in abundance in post-glacial accumulations. it was undoubtedly a contemporary of the earlier races of men in western europe; and it may perhaps be regarded as being the actual substantial kernel of some of the "dragons" of fable. [illustration: fig. .--skull of the tichorhine rhinoceros, the horns being wanting. one-tenth of the natural size. post-pliocene deposits of europe and asia.] the only other odd-toed ungulate which needs notice is the so-called _equus fossilis_ of the post-pliocene of europe. this made its appearance before the glacial period, and appears to be in reality identical with the existing horse (_equus caballus_). true horses also occur in the post-pliocene of north america; but, from some cause or another, they must have been exterminated before historic times. [illustration: fig. --skeleton of the "irish elk" (_cervus megaceros_). post-pliocene, britain.] amongst the even-toed ungulates, the great _hippopotamus major_ of the pliocene still continued to exist in post-pliocene times in western europe; and the existing wild boar (_sus scrofa_), the parent of our domestic breeds of pigs, appeared for the first time. the old world possessed extinct representatives of its existing camels, and lost types of the living llamas inhabited south america. amongst the deer, the post-pliocene accumulations have yielded the remains of various living species, such as the red deer (_cervus elaphus_), the reindeer (_cervus tarandus_), the moose or elk (_alces malchis_), and the roebuck (_cervus capreolus_), together with a number of extinct forms. among the latter, the great "irish elk" (_cervus megaceros_) is justly celebrated both for its size and for the number and excellent preservation of its discovered remains. this extinct species (fig. ) has been found principally in peat-mosses and post-pliocene lake-deposits, and is remarkable for the enormous size of the spreading antlers, which are widened out towards their extremities, and attain an expanse of over ten feet from tip to tip. it is not a genuine elk, but is intermediate between the reindeer and the fallow-deer. among the existing deer of the post-pliocene, the most noticeable is the reindeer, an essentially northern type, existing at the present day in northern europe, and also (under the name of the "caribou") in north america. when the cold of the glacial period became established, this boreal species was enabled to invade central and western europe in great herds, and its remains are found abundantly in cave-earths and other post-pliocene deposits as far south as the pyrenees. [illustration: fig. .--skull of the urns (_bos primigenius_). post-pliocene and recent. (after owen.)] in addition to the above, the post-pliocene deposits of europe and north america have yielded the remains of various sheep and oxen. one of the most interesting of the latter is the "urus" or wild bull (_bos primigenius_, fig. ), which, though much larger than any of the existing fossils, is believed to be specifically undistinguishable from the domestic ox (_bos taurus_), and to be possibly the ancestor of some of the larger european varieties of oxen. in the earlier part of its existence the urus ranged over europe and britain in company with the woolly rhinoceros and the mammoth; but it long survived these, and does not appear to have been finally exterminated till about the twelfth century. another remarkable member of the post-pliocene cattle, also to begin with an associate of the mammoth and rhinoceros, is the european bison or "aurochs" (_bison priscus_). this "maned" ox formerly abounded in europe in post-glacial times, and was not rare even in the later periods of the roman empire, though much diminished in numbers, and driven back into the wilder and more inaccessible parts of the country. at present this fine species has been so nearly exterminated that it no longer exists in europe save in lithuania, where its preservation has been secured by rigid protective laws. lastly, the post-pliocene deposits have yielded the remains of the singular living animal which is known as the musk-ox or musk-sheep (_ovibos moschatus_). at the present day, the musk-ox is an inhabitant of the "barren grounds" of arctic america, and it is remarkable for the great length of its hair. it is, like the reindeer, a distinctively northern animal; but it enjoyed during the glacial period a much wider range than it has at the present day, the conditions suitable for its existence being then extended over a considerable portion of the northern hemisphere. thus remains of the musk-ox are found in greater or less abundance in post-pliocene deposits over a great part of europe, extending even to the south of france; and closely-related forms are found in similar deposits in the united states. [illustration: fig. .--skeleton of the mammoth (_elephas primigenius_). portions of the integument still adhere to the head, and the thick skin of the soles is still attached to the feet. post-pliocene.] coming to the _proboscideans_, we find that the _mastodons_ seem to have disappeared in europe at the close of the pliocene period, or at the very commencement of the post-pliocene. in the new world, on the other hand, a species of mastodon (_m. americanus_ or _m. ohioticus_) is found abundantly in deposits of post-pliocene age, from canada to texas. very perfect skeletons of this species have been exhumed from morasses and swamps, and large individuals attained a length (exclusive of the tusks) of seventeen feet and a height of eleven feet, the tusks being twelve feet in length. remains of _elephants_ are also abundant in the post-pliocene deposits of both the old and the new world. amongst these, we find in europe the two familiar pliocene species _e. meridionales_ and _e. antiquus_ still surviving, but in diminished numbers. with these are found in vast abundance the remains of the characteristic elephant of the post-pliocene, the well-known "mammoth" (elephas primigenius_), which is accompanied in north america by the nearly-allied, but more southern species, the _elephas americanus_. the mammoth (fig. ) is considerably larger than the largest of the living elephants, the skeleton being over sixteen feet in length, exclusive of the tusks, and over nine feet in height. the tusks are bent almost into a circle, and are sometimes twelve feet in length, measured along their curvature. in the frozen soil of siberia several carcasses of the mammoth have been discovered with the flesh and skin still attached to the bones, the most celebrated of these being a mammoth which was discovered at the beginning of this century at the mouth of the lena, on the borders of the frozen sea, and the skeleton of which is now preserved at st petersburg (fig. ). from the occurrence of the remains of the mammoth in vast numbers in siberia, it might have been safely inferred that this ancient elephant was able to endure a far more rigorous climate than its existing congeners. this inference has, however, been rendered a certainty by the specimens just referred to, which show that the mammoth was protected against the cold by a thick coat of reddish-brown wool, some nine or ten inches long, interspersed with strong, coarse black hair more than a foot in length. the teeth of the mammoth (fig. ) are of the type of those of the existing indian elephant, and are found in immense numbers in certain localities. the mammoth was essentially northern in its distribution, never passing south of a line drawn through the pyrenees, the alps, the northern shores of the caspian, lake baikal, kamschatka, and the stanovi mountains (dawkins). it occurs in the pre-glacial forest-bed of cromer in norfolk, survived the glacial period, and is found abundantly in post-glacial deposits in france, germany, britain, russia in europe, asia, and north america, being often associated with the reindeer, lemming, and musk-ox. that it survived into the earlier portion of the human period is unquestionable, its remains having been found in a great number of instances associated with implements of human manufacture; whilst in one instance a recognisable portrait of it has been discovered, carved on bone. [illustration: fig. .--molar tooth of the mammoth (_elephas primigenius_), upper jaw, right side, one-third of the natural size. a, grinding surface; b, side view. post-pliocene.] amongst other elephants which occur in post-pliocene deposits may be mentioned, as of special interest, the pigmy elephants of malta. one of these--the _elephas melitensis_, or so-called "donkey-elephant"--was not more than four and a half feet in height. the other--the _elephas falconeri_, of busk--was still smaller, its average height at the withers not exceeding two and a half to three feet. [illustration: fig. .--skull of _ursus spelpeus_. post-pliocene, europe. one-sixth of the natural size.] whilst herbivorous animals abounded during the post-pliocene, we have ample evidence of the coexistence with them of a number of carnivorous forms, both in the new and the old world. the bears are represented in europe by at least three species, two of which--namely, the great grizzly bear (_ursus ferox_) and the smaller brown bear (_ursus arctos_)--are in existence at the present day. the third species is the celebrated cave-bear (_ursus speloeus_, fig. ), which is now extinct. the cave-bear exceeded in its dimensions the largest of modern bears; and its remains, as its name implies; have been found mainly in cavern-deposits. enormous numbers of this large and ferocious species must have lived in europe in post-glacial times; and that they survived into the human period, is clearly shown by the common association of their bones with the implements of man. they are occasionally accompanied by the remains of a glutton (the _gulo speloeus_), which does not appear to be really separable from the existing wolverine or glutton of northern regions (the _gulo luscus_). in addition, we meet with the bones of the wolf, fox, weasel, otter, badger, wild cat, panther, hyæna, and lion, &c., together with the extinct _machairodus_ or "sabre-toothed tiger." the only two of these that deserve further mention are the hyæna and the lion. the cave-hyæna (_hyoena speloea_, fig. ) is regarded by high authorities as nothing more than a variety of the living spotted hyæna (_h. crocuta_) of south africa. this well-known species inhabited britain and a considerable portion of europe during a large part of the post-pliocene period; and its remains often occur in great abundance. indeed, some caves, such as the kirkdale cavern in yorkshire, were dens inhabited during long periods by these animals, and thus contain the remains of numerous individuals and of successive generations of hyænas, together with innumerable gnawed and bitten bones of their prey. that the cave-hyæna was a contemporary with man in western europe during post-glacial times is shown beyond a doubt by the common association of its bones with human implements. [illustration: fig. .--skull of _hyoena speloea_, one-fourth of the natural size. post-phocene, europe.] lastly, the so-called cave-lion (_felis speloea_), long supposed to be a distinct species, has been shown to be nothing more than a large variety of the existing lion (_felis leo_). this animal inhabited britain and western europe in times posterior to the glacial period, and was a contemporary of the cave-hyæna, cave-bear, woolly rhinoceros, and mammoth. the cave-lion also unquestionably survived into the earlier portion of the human period in europe. the post-pliocene deposits of europe have further yielded the remains of numerous _rodents_--such as the beaver, the northern lemming, marmots, mice, voles, rabbits, &c.--together with the gigantic extinct beaver known as the _trogontherium cuvieri_ (fig. ). the great _castoroides ohioensis_ of the post-pliocene of north america is also a great extinct beaver, which reached a length of about five feet. lastly, the brazilian bone-caves have yielded the remains of numerous rodents of types now characteristic of south america, such as guinea-pigs, capybaras, tree-inhabiting porcupines, and coypus. [illustration: fig. .--lower jaw of _trogontherium cuvieri_, one-fourth of the natural size. post-pliocene, britain.] the deposits just alluded to have further yielded the remains of various monkeys, such as howling monkeys, squirrel monkeys, and marmosets, all of which belong to the group of _quadrumana_ which is now exclusively confined to the south american continent--namely, the "platyrhine" monkeys. we still have very briefly to consider the occurrence of man in post-pliocene deposits; but before doing so, it will be well to draw attention to the evidence afforded by the post-pliocene mammals as to the climate of western europe at this period. the chief point which we have to notice is, that a considerable revolution of opinion has taken place on this point. it was originally believed that the presence of such animals as elephants, lions, the rhinoceros, and the hippopotamus afforded an irrefragable proof that the climate of europe must have been a warm one, at any rate during post-glacial times. the existence, also, of numbers of mammoths in siberia, was further supposed to indicate that this high temperature extended itself very far north. upon the whole, however, the evidence is against this view. not only is there great difficulty in supposing that the arctic conditions of the glacial period were immediately followed by anything warmer than a cold-temperate climate; but there is nothing in the nature of the mammals themselves which would absolutely forbid their living in a temperate climate. the _hippopotamus major_, though probably clad in hair, offers some difficulty--since, as pointed out by professor busk, it must have required a climate sufficiently warm to insure that the rivers were not frozen over in the winter; but it was probably a migratory animal, and its occurrence may be accounted for by this. the woolly rhinoceros and the mammoth are known with certainty to have been protected with a thick covering of wool and hair; and their extension northwards need not necessarily have been limited by anything except the absence of a sufficiently luxuriant vegetation to afford them food. the great american mastodon, though not certainly known to have possessed a hairy covering, has been shown to have lived upon the shoots of spruce and firs, trees characteristic of temperate regions--as shown by the undigested food which has been found with its skeleton, occupying the place of the stomach. the lions and hyænas, again, as shown by professor boyd dawkins, do not indicate necessarily a warm climate. wherever a sufficiency of herbivorous animals to supply them with food can live, there they can live also; and they have therefore no special bearing upon the question of climate. after a review of the whole evidence, professor dawkins concludes that the nearest approach at the present day to the post-pliocene climate of western europe is to be found in the climate of the great siberian plains which stretch from the altai mountains to the frozen sea. "covered by impenetrable forests, for the most part of birch, poplar, larch, and pines, and low creeping dwarf cedars, they present every gradation in climate from the temperate to that in which the cold is too severe to admit of the growth of trees, which decrease in size as the traveller advances northwards, and are replaced by the grey mosses and lichens that cover the low marshy 'tundras.' the maximum winter cold, registered by admiral von wrangel at nishne kolymsk, on the banks of the kolyma, is-- ° in january. 'then breathing becomes difficult; the reindeer, that citizen of the polar region, withdraws to the deepest thicket of the forest, and stands there motionless as if deprived of life;' and trees burst asunder with the cold. throughout this area roam elks, black bears, foxes, sables, and wolves, that afford subsistence to the jakutian and tungusian fur-hunters. in the northern part countless herds of reindeer, elks, foxes, and wolverines make up for the poverty of vegetation by the rich abundance of animal life. 'enormous flights of swans, geese, and ducks arrive in the spring, and seek deserts where they may moult and build their nests in safety. ptarmigans run in troops amongst the bushes; little snipes are busy along the brooks and in the morasses; the social crows seek the neighbourhood of new habitations; and when the sun shines in spring, one may even sometimes hear the cheerful note of the finch, and in autumn that of the thrush.' throughout this region of woods, a hardy, middle-sized breed of horses lives under the mastership and care of man, and is eminently adapted to bear the severity of the climate.... the only limit to their northern range is the difficulty of obtaining food. the severity of the winter through the southern portion of this vast wooded area is almost compensated for by the summer heat and its marvellous effect on vegetation."--(dawkins, 'monograph of pleistocene mammalia.') finally, a few words must be said as to the occurrence of the remains of man in post-pliocene deposits. that man existed in western europe and in britain during the post-pliocene period, is placed beyond a doubt by the occurrence of his bones in deposits of this age, along with the much more frequent occurrence of implements of human manufacture. at what precise point of time during the post-pliocene period he first made his appearance is still a matter of conjecture. recent researches would render it probable that the early inhabitants of britain and western europe were witnesses of the stupendous phenomena of the glacial period; but this cannot be said to have been demonstrated. that man existed in these regions during the post-glacial division of post-pliocene time cannot be doubted for a moment. as to the physical peculiarities of the ancient races that lived with the mammoth and the woolly rhinoceros, little is known compared with what we may some day hope to know. such information as we have, however, based principally on the skulls of the engis, neanderthal, cro-magnon, and bruniquel caverns, would lead to the conclusion that post-pliocene man was in no respect inferior in his organisation to, or less highly developed than, many existing races. all the known skulls of this period, with the single exception of the neanderthal cranium, are in all respects average and normal in their characters; and even the neanderthal skull possessed a cubic capacity at least equal to that of some existing races. the implements of post-pliocene man are exclusively of stone or bone; and the former are invariably of rude shape and _undressed_. these "palæolithic" tools (gr. _palaios_; ancient; _lithos_, stone) point to a very early condition of the arts; since the men of the earlier portion of the recent period, though likewise unacquainted with the metals, were in the habit of polishing or dressing the stone implements which they fabricated. it is impossible here to enter further into this subject; and it would be useless to do so without entering as well into a consideration of the human remains of the recent period--a period which lies outside the province of the present work. so far as post-pliocene man is concerned, the chief points which the palæontological student has to remember have been elsewhere summarised by the author as follows:-- . man unquestionably existed during the later portion of what sir charles lyell has termed the "post-pliocene" period. in other words, man's existence dates back to a time when several remarkable mammals, previously mentioned, had not yet become extinct; but he does not date back to a time anterior to the present _molluscan_ fauna. . the antiquity of the so-called post-pliocene period is a matter which must be mainly settled by the evidence of geology proper, and need not be discussed here. . the extinct mammals with which man coexisted in western europe are mostly of large size, the most important being the mammoth (_elephas primogenius_), the woolly rhinoceros (_rhinoceros tichorhinus_), the cave-lion (_felis speloea_), the cave-hyæna(_hyoena speloea), and the cave-bear (_ursus speloeus_). we do not know the causes which led to the extinction of these mammals; but we know that hardly any mammalian species has become extinct during the historical period. . the extinct mammals with which man coexisted are referable in many cases to species which presumably required a very different climate to that now prevailing in western europe. how long a period, however, has been consumed in the bringing about of the climatic changes thus indicated, we have no means of calculating with any approach to accuracy. . some of the deposits in which the remains of man have been found associated with the bones of extinct mammals, are such as to show incontestably that great changes in the physical geography and surface-configuration of western europe have taken place since the period of their accumulation. we have, however, no means at present of judging of the lapse of time thus indicated except by analogies and comparisons which may be disputed. . the human implements which are associated with the remains of extinct mammals, themselves bear evidence of an exceedingly barbarous condition of the human species. post-pliocene or "palæolithic" man was clearly unacquainted with the use of any of the metals. not only so, but the workmanship of these ancient races was much inferior to that of the later tribes, who were also ignorant of the metals, and who also used nothing but weapons and tools of stone, bone, &c. . lastly, it is only with the human remains of the post-pliocene period that the palæontologist proper has to deal. when we enter the "recent" period, in which the remains of man are associated with those of _existing species of mammals_, we pass out of the region of pure palæontology into the domain of the archæologist and the ethnologist. literature. the following are some of the principal works and memoirs to which the student may refer for information as to the post-pliocene deposits and the remains which they contain, as well as to the primitive races of mankind:-- ( ) 'elements of geology.' lyell. ( ) 'antiquity of man.' lyell. ( ) 'palæontological memoirs.' falconer. ( ) 'the great ice-age.' james geikie. ( ) 'manual of palæontology.' owen. ( ) 'british fossil mammals and birds.' owen. ( ) 'cave-hunting.' boyd dawkins. ( ) 'prehistoric times.' lubbock. ( ) 'ancient stone implements.' evans. ( ) 'prehistoric man.' daniel wilson. ( ) 'prehistoric races of the united states.' foster. ( ) 'manual of geology.' dana. ( ) 'monograph of pleistocene mammalia' (palæontographical society). boyd dawkins and sanford. ( ) 'monograph of the post-tertiary entomostraca of scotland, &c., with an introduction on the post-tertiary deposits of scotland' (ibid.) g. s. brady, h. w. crosskey, and d. robertson. ( ) "reports on kent's cavern"--'british association reports.' pengelly. ( ) "reports on the victoria cavern, settle"--'british association reports.' tiddeman. ( ) 'ossemens fossiles.' cuvier. ( ) 'reliquiæ diluvianæ.' buckland. ( ) "fossil mammalia"--'zoology of the voyage of the beagle.' owen. ( ) 'description of the tooth and part of the skeleton of the _glyptodon_.' owen. ( ) "memoir on the extinct sloth tribe of north america"--'smithsonian contributions to knowledge.' leidy. ( ) "report on extinct mammals of australia"--'british association,' . owen. ( ) 'description of the skeleton of an extinct gigantic sloth (_mylodon robtutus_).' owen. ( ) "affinities and probable habits of thylacoleo"--'quart. journ. geol. soc.,' vol. xxiv. flower. ( ) 'prodromus of the palæontology of victoria.' m'coy. ( ) 'les ossemens fossiles des cavernes de liège.' schmerling. ( ) 'die fauna der pfahlbauten in der schweiz.' rütimeyer. ( ) "extinct and existing bovine animals of scandinavia"--'annals of natural history,' ser. , vol. iv., . nilsson. ( ) 'man's place in nature.' huxley. ( ) 'les temps antéhistoriques en belgique.' dupont. ( ) "classification of the pleistocene strata of britain and the continent"--'quart. journ. geol. soc.,' vol. xxviii. boyd dawkins. ( ) 'distribution of the post-glacial mammalia' (ibid.), vol. xxv. boyd dawkins. ( ) 'on british fossil oxen' (ibid.), vols. xxii. and xxiii. boyd dawkins. ( ) 'british prehistoric mammals' (congress of prehistoric archæology, ). boyd dawkins. ( ) 'reliquiæ aquitanicæ.' lartet and christy. ( ) 'zoologie et paléontologie françaises.' gervais. ( ) 'notes on the post-pliocene geology of canada.' dawson. ( ) "on the connection between the existing fauna and flora of great britain and certain geological changes"--'mem. geol. survey.' edward forbes. ( ) 'cavern-researches.' m'enery. edited by vivian. ( ) "quaternary gravels"--'quart. journ. geol. soc.,' vol. xxv. tylor. chapter xxiii. the succession of life upon the globe. in conclusion, it may not be out of place if we attempt to summarise, in the briefest possible manner, some of the principal results which may be deduced as to the succession of life upon the earth from the facts which have in the preceding portion of this work been passed in review. that there was a time when the earth was void of life is universally admitted, though it may be that the geological record gives us no direct evidence of this. that the globe of to-day is peopled with innumerable forms of life whose term of existence has been, for the most part, but as it were of yesterday, is likewise an assertion beyond dispute. can we in any way connect the present with the remote past, and can we indicate even imperfectly the conditions and laws under which the existing order was brought about? the long series of fossiliferous deposits, with their almost countless organic remains, is the link between what has been and what is; and if any answer to the above question can be arrived at, it will be by the careful and conscientious study of the facts of palæontology. in the present state of our knowledge, it may be safely said that anything like a dogmatic or positive opinion as to the precise sequence of living forms upon the globe, and still more as to the manner in which this sequence may have been brought about, is incapable of scientific proof. there are, however, certain general deductions from the known facts which may be regarded as certainly established. in the first place, it is certain that there has been a _succession_ of life upon the earth, different specific and generic types succeeding one another in successive periods. it follows from this, that the animals and plants with which we are familiar as living, were not always upon the earth, but that they have been preceded by numerous races more or less differing from them. what is true of the species of animals and plants, is true also of the higher zoological divisions; and it is, in the second place, quite certain that there has been a similar _succession_ in the order of appearance of the primary groups ("sub-kingdoms," "classes," &c.) of animals and vegetables. these great groups did not all come into existence at once, but they made their appearance successively. it is true that we cannot be said to be certainly acquainted with the first _absolute_ appearance of any great group of animals. no one dare assert positively that the apparent first appearance of fishes in the upper silurian is really their first introduction upon the earth: indeed, there is a strong probability against any such supposition. to whatever extent, however, future discoveries may push back the first advent of any or of all of the great groups of life, there is no likelihood that anything will be found out which will materially alter the _relative_ succession of these groups as at present known to us. it is not likely, for example, that the future has in store for us any discovery by which it would be shown that fishes were in existence before molluscs, or that mammals made their appearance before fishes. the sub-kingdoms of invertebrate animals were all represented in cambrian times--and it might therefore be inferred that _these_ had all come simultaneously into existence; but it is clear that this inference, though incapable of actual disproof, is in the last degree improbable. anterior to the cambrian is the great series of the laurentian, which, owing to the metamorphism to which it has been subjected, has so far yielded but the singular _eozoön_. we may be certain, however, that others of the invertebrate sub-kingdoms besides the protozoa were in existence in the laurentian period; and we may infer from known analogies that they appeared successively, and not simultaneously. when we come to smaller divisions than the sub-kingdoms--such as classes, orders, and families--a similar succession of groups is observable. the different classes of any given sub-kingdom, or the different orders of any given class, do not make their appearance together and all at once, but they are introduced upon the earth in _succession_. more than this, the different classes of a sub-kingdom, or the different orders of a class, _in the main succeed one another in the relative order of their zoological rank--the lower groups appearing first and the higher groups last_. it is true that in the cambrian formation--the earliest series of sediments in which fossils are abundant--we find numerous groups, some very low, others very high, in the zoological scale, which _appear_ to have simultaneously flashed into existence. for reasons stated above, however, we cannot accept this appearance as real; and we must believe that many of the cambrian groups of animals really came into being long before the commencement of the cambrian period. at any rate, in the long series of fossiliferous deposits of later date than the cambrian the above-stated rule holds good as a broad generalisation--that the lower groups, namely, precede the higher in point of time; and though there are apparent exceptions to the rule, there are none of such a nature as not to admit of explanation. some of the leading facts upon which this generalisarion is founded will be enumerated immediately; but it will be well, in the first place, to consider briefly what we precisely mean when we speak of "higher" and "lower" groups. it is well known that naturalists are in the habit of "classifying" the innumerable animals which now exist upon the globe; or, in other words, of systematically arranging them into groups. the precise arrangement adopted by one naturalist may differ in minor details from that adopted by another; but all are agreed as to the fundamental points of classification, and all, therefore, agree in placing certain groups in a certain sequence. what, then, is the principle upon which this sequence is based? why, for example, are the sponges placed below the corals; these below the sea-urchins; and these, again, below the shell-fish? without entering into a discussion of the principles of zoological classification, which would here be out of place, it must be sufficient to say that the sequence in question is based upon the _relative type of organisation_ of the groups of animals classified. the corals are placed above the sponges upon the ground that, regarded as a whole, the _plan or type of structure_ of a coral is more complex than that of a sponge. it is not in the slightest degree that the sponge is in any respect less highly organised or less perfect, as a sponge, than is the coral as a coral. each is equally perfect in its own way; but the structural pattern of the coral is the highest, and therefore it occupies a higher place in the zoological scale. it is upon this principle, then, that the primary subdivisions of the animal kingdom (the so-called "sub-kingdoms") are arranged in a certain order. coming, again, to the minor subdivisions (classes, orders, &c.) of each sub-kingdom, we find a different but entirely analogous principle employed as a means of classification. the numerous animals belonging to any given sub-kingdom are formed upon the same fundamental plan of structure; but they nevertheless admit of being arranged in a regular series of groups. all the shell-fish, for example, are built upon a common plan, this plan representing the ideal mollusc; but there are at the same time various groups of the _mollusca_, and these groups admit of an arrangement in a given sequence. the principle adopted in this case is simply of _the relative elaboration of the common type_. the oyster is built upon the same ground-plan as the cuttle-fish; but this plan is carried out with much greater elaboration, and with many more complexities, in the latter than in the former: and in accordance with this, the _cephalopoda_ constitute a higher group than the bivalve shell-fish. as in the case of superiority of structural type, so in this case also, it is not in the least that the oyster is an _imperfect_ animal. on the contrary, it is just as perfectly adapted by its organisation to fill its own sphere and to meet the exigencies of its own existence as is the cuttle-fish; but the latter lives a life which is, physiologically, higher than the former, and its organisation is correspondingly increased in complexity. this being understood, it may be repeated that, in the main, the succession of life upon the globe in point of _time_ has corresponded with the relative order of succession of the great groups of animals in _zoological rank_; and some of the more striking examples of this may be here alluded to. amongst the _echinoderms_, for instance, the two orders generally admitted to be the "lowest" in the zoological scale--namely, the _crinoids_ and the _cystoids_--are likewise the oldest, both, appearing in the cambrian, the former slowly dying out as we approach the recent period, and the latter disappearing wholly before the close of the palæozoic period. amongst the _crustaceans_, the ancient groups of the trilobites, ostracodes, phyllopods, eurypterids, and limuloids, some of which exist at the present day, are all "low" types; whereas the highly-organised decapods do not make their appearance till near the close of the palæozoic epoch, and they do not become abundant till we reach mesozoic times. amongst the _mollusca_, those bivalves which possess breathing-tubes (the "siphonate" bivalves) are generally admitted to be higher than those which are destitute of these organs (the "asiphonate" bivalves); and the latter are especially characteristic of the palæozoic period, whilst the former abound in mesozoic and kainozoic formations. similarly, the univalves with breathing-tubes and a corresponding notch in the mouth of the shell ("siphonostomatous" univalves) are regarded as higher in the scale than the round-mouthed vegetable-eating sea-snails, in which no respiratory siphons exist ("holostomatous" univalves); but the latter abound in the palæozoic rocks--whereas the former do not make their appearance till the jurassic period, and their higher groups do not seem to have existed till the close of the cretaceous. the _cephalopods_, again--the highest of all the groups of mollusca--are represented in the palæozoic rocks exclusively by tetrabranchiate forms, which constitute the lowest of the two orders of this class; whereas the more highly specialised dibranchiates do not make their appearance till the commencement of the mesozoic. the palæozoic tetrabranchiates, also, are of a much simpler type than the highly complex _ammonitidoe_ of the mesozoic. similar facts are observable amongst the _vertebrate animals_. the fishes are the lowest class of vertebrates, and they are the first to appear, their first certain occurrence being in the upper silurian; whilst, even if the lower silurian and upper cambrian "conodonts" were shown to be the teeth of fishes, there would still remain the enormously long periods of the laurentian and lower cambrian, during which there were invertebrates, but no vertebrates. the _amphibians_, the next class in zoological order, appears later than the fishes, and is not represented till the carboniferous; whilst its highest group (that of the frogs and toads) does not make its entrance upon the scene till tertiary times are reached. the class of the _reptiles_, again, the next in order, does not appear till the permian, and therefore not till after amphibians of very varied forms had been in existence for a protracted period. the _birds_ seem to be undoubtedly later than the reptiles; but, owing to the uncertainty as to the exact point of their first appearance, it cannot be positively asserted that they preceded mammals, as they should have done. finally, the mesozoic types of _mammals_ are mainly, if not exclusively, referable to the _marsupials_, one of the lowest orders of the class; whilst the higher orders of the "placental" quadrupeds are not with certainty known to have existed prior to the commencement of the tertiary period. facts of a very similar nature are offered by the succession of plants upon the globe. thus the vegetation of the palæozoic period consisted principally of the lowly-organised groups of the cryptogamous or flowerless plants. the mesozoic formations, up to the chalk, are especially characterised by the naked-seeded flowering plants--the conifers and the cycads; whilst the higher groups of the angiospermous exogens and monocotyledons characterise the upper cretaceous and tertiary rocks. facts of the above nature--and they could be greatly multiplied--seem to point clearly to the existence of some law of progression, though we certainly are not yet in a position to formulate this law, or to indicate the precise manner in which it has operated. two considerations, also, must not be overlooked. in the first place, there are various groups, some of them highly organised, which make their appearance at an extremely ancient date, but which continue throughout geological time almost unchanged, and certainly unprogressive. many of these "persistent types" are known--such as various of the _foraminifera_, the _linguloe_, the _nautili_, &c.; and they indicate that under given conditions, at present unknown to us, it is possible for a life-form to subsist for an almost indefinite period without any important modification of its structure. in the second place, whilst the facts above mentioned point to some general law of progression of the great zoological groups, it cannot be asserted that the primeval types _of any given group_ are necessarily "lower," zoologically speaking, than their modern representatives. nor does this seem to be at all necessary for the establishment of the law in question. it cannot be asserted, for example, that the ganoid and placoid fishes of the upper silurian are in themselves less highly organised than their existing representatives; nor can it even be asserted that the ganoid and placoid orders are low _groups_ of the class _pisces_. on the contrary, they are high groups; but then it must be remembered that these are probably not really the first fishes, and that if we meet with fishes at some future time in the lower silurian or cambrian, these may easily prove to be representatives of the lower orders of the class. this question cannot be further entered into here, as its discussion could be carried out to an almost unlimited length; but whilst there are facts pointing both ways, it appears that at present we are not justified in asserting that the earlier types of each group--so far as these are known to us, or really are without predecessors--are _necessarily_ or _invariably_ more "degraded" or "embryonic" in their structure than their more modern representatives. it remains to consider very briefly how far palæontology supports the doctrine of "evolution," as it is called; and this, too, is a question of almost infinite dimensions, which can but be glanced at here. does palæontology teach us that the almost innumerable kinds of animals and plants which we know to have successively flourished upon the earth in past times were produced separately and wholly independently of each other, at successive periods? or does it point to the theory that a large number of these supposed distinct forms, have been in reality produced by the slow modification of a comparatively small number of primitive types? upon the whole, it must be unhesitatingly replied that the evidence of palæontology is in favour of the view that the succession of life-forms upon the globe has been to a large extent regulated by some orderly and constantly-acting law of modification and evolution. upon no other theory can we comprehend how the fauna of any given formation is more closely related to that of the formation next below in the series, and to that of the formation next above, than to that of any other series of deposits. upon no other view can we comprehend why the post-tertiary mammals of south america should consist principally of edentates, llamas, tapirs, peccaries, platyrhine monkeys, and other forms now characterising this continent; whilst those of australia should be wholly referable to the order of marsupials. on no other view can we explain the common occurrence of "intermediate" or "transitional" forms of life, filling in the gaps between groups now widely distinct. on the other hand, there are facts which point clearly to the existence of some law other than that of evolution, and probably of a deeper and more far-reaching character. upon no theory of evolution can we find a satisfactory explanation for the constant introduction throughout geological time of new forms of life, which do not appear to have been preceded by pre-existent allied types; the graptolites and trilobites have no known predecessors, and leave no known successors. the insects appear suddenly in the devonian, and the arachnides and myriapods in the carboniferous, under well-differentiated and highly-specialised types. the dibranchiate cephalopods appear with equal apparent suddenness in the older mesozoic deposits, and no known type of the palæozoic period can be pointed to as a possible ancestor. the _hippuritidoe_ of the cretaceous burst into a varied life to all appearance almost immediately after their first introduction into existence. the wonderful dicotyledonous flora of the upper cretaceous period similarly surprises us without any prophetic annunciation from the older jurassic. many other instances could be given; but enough has been said to show that there is a good deal to be said on both sides, and that the problem is one environed with profound difficulties. one point only seems now to be universally conceded, and that is, that the record of life in past time is not interrupted by gaps other than those due to the necessary imperfections of the fossiliferous series, to the fact that many animals are incapable of preservation in a fossil condition, or to other causes of a like nature. all those who are entitled to speak on this head are agreed that the introduction of new and the destruction of old species have been slow and gradual processes, in no sense of the term "catastrophistic." most are also willing to admit that "evolution" has taken place in the past, to a greater or less extent, and that a greater or less number of so-called species of fossil animals are really the modified descendants of pre-existent forms. _how_ this process of evolution has been effected, to what extent it has taken place, under what conditions and laws it has been carried out, and how far it may be regarded as merely auxiliary and supplemental to some deeper law of change and progress, are questions to which, in spite of the brilliant generalisations of darwin, no satisfactory answer can as yet be given. in the successful solution of this problem--if soluble with the materials available to our hands--will lie the greatest triumph that palæontology can hope to attain; and there is reason to think that, thanks to the guiding-clue afforded by the genius of the author of the 'origin of species,' we are at least on the road to a sure, though it may be a far-distant, victory. appendix. tabular view of the chief divisions of the animal kingdom. (extinct groups are marked with an asterisk. groups not represented at all as fossils are marked with two asterisks.) invertebrate animals. sub-kingdom i.--protozoa. animal simple or compound; body composed of "sarcode," not definitely segmented; no nervous system; and no digestive apparatus, beyond occasionally a mouth and gullet. class i. gregarinidÆ.** class ii. rhizopoda. _order_ . _monera_.** " . _amoebea_.** " . _foraminifera_. " . _radiolaria_ (polycystines, &c.) " . _spongida_ (sponges). class iii. infusoria.** sub-kingdom ii.--coelenterata. animal simple or compound; body-wall composed of two principal layers; digestive canal freely communicating with the general cavity of the body; no circulating organs, and no nervous system or a rudimentary one; mouth surrounded by tentacles, arranged, like the internal organs, in a "radiate" or star-like manner. class i. hydrozoa. _sub-class_ . _hydroida_ ("hydroid zoophytes"). _ex._ fresh-water polypes,** pipe-corallines (_tubularia_), sea-firs (_sertularia_). _sub-class_ . _siphonophora_** ("oceanic hydrozoa"). _ex_. portuguese man-of-war (_physalia_). _sub-class_ . _discophora_ ("jelly-fishes"). only known as fossils by impressions of their stranded carcasses. _sub-class_ . _lucernarida_ ("sea-blubbers"). also only known as fossils by impressions left in fine-grained strata. _sub-class_ . _graptolitidoe_* ("graptolites"). class ii. actinozoa. _order_ . _zoantharia_. _ex_. sea-anemones** (_actinidoe_), star-corals (_astroeidoe_). _order_ . _alcyonaria_. _ex_. sea-pens (_pennatula_), organ-pipe coral (_tubipora_), red coral (_corallium_). _order_ . _rugosa_ ("rugose corals"). " . _ctenophora_.** _ex_. venus's girdle (_cestum_). sub-kingdom iii.--annuloida. animals in which the digestive canal is completely shut off from the cavity of the body; a distinct nervous system; a system of branched "water-vessels," which usually communicate with the exterior. body of the adult often "radiate," and never composed of a succession of definite rings. class i. echinodermata. _order_ . _crinoidea_ ("sea-lilies"). _ex_. feather-star (_comatula_), stone-lily (_encrinus_*). _order_ . _blastoidea_* ("pentremites"). " . _cystoidea_* ("globe-lilies"). " . _ophiuroidea_ ("brittle-stars"). _ex_. sand-stars (_ophiura_), brittle-stars (_ophiocoma_). _order_ . _asteroidea_ ("star-fishes"). ex. cross-fish (_uraster_), sun-star (_solaster_). _order_ . _echinoidea_ ("sea-urchins"). ex. sea-eggs (_echinus_), heart-urchins (_spatangus_). _order_ . _holothuroidea_ ("sea-cucumbers"). _ex_. trepangs (_holothuria_). class ii. scolecida** (intestinal worms, wheel animalcules, &c.) sub-kingdom iv.--annulosa. animal composed of numerous definite segments placed one behind the other; nervous system forming a knotted cord placed along the lower (ventral) surface of the body. _division a. anarthropoda_. no jointed limbs. class i. gephyrea** ("spoon-worms"). class ii. annelida. ("ringed-worms"). _ex_. leeches** (_hirudinea_), earthworms** (_oligochoeta_), tube-worms (_tubicola_), sea-worms and sea-centipedes (_errantia_). class iii. chÆtognatha** ("arrow-worms"). _division b. arthropoda or articulata_. limbs jointed to the body. class i. crustacea ("crustaceans"). _ex_. barnacles and acorn-shells (_cirripedia_), water-fleas (_ostracoda_), brine-shrimps and fairy-shrimps (_phyllopoda_), trilobites* (_trilobita_), king-crabs and eurypterids* (_merostomata_), wood-lice and slaters (_isopoda_), sand-hoppers (_amphipoda_), lobsters, shrimps, hermit-crabs, and crabs (_decapoda_). class ii. arachnida. _ex._ mites (_acarina_), scorpions (_pedipalpi_), spiders (_araneida_). class iii. myriapoda. _ex._ centipedes (_chilopoda_), millipedes and galley-worms (_chilignatha_). class iv. insecta ("insects"). _ex_. field-bugs (_hemiptera_); crickets, grasshoppers, &c. (_orthoptera_); dragon-flies and may-flies (_neuroptera_); goats and house-flies (_diptera_); butterflies and moths (_lepidoptera_); bees, wasps, and ants (_hymenoptera_); beetles (_coleoptera_). sub-kingdom v.--mollusca. animal soft-bodied, generally with a hard covering or shell; no distinct segmentation of the body; nervous system of scattered masses. class i. polyzoa ("sea-mosses"). _ex_. sea-mats (_flustra_), lace-corals (_fenestellidoe_*). class ii. tunicata** ("tunicaries"). _ex_. sea-squirts (_ascidia_). class iii. brachiopoda ("lamp-shells"). _ex_. goose-bill lamp-shell (_lingula_). class iv. lamellibranchiata ("bivalves"). _ex_. oyster (_ostrea_), mussel (_mytilus_), scallop (_pecten_), cockle (_cardium_). class v. gasteropoda ("univalves"). _ex_. whelks (_buccinum_), limpets (_patella_), sea-slugs** (_doris_), land-snails (_helix_). class vi. pteropoda ("winged snails"). ex. _hyalea, cleodora_. class vii. cephalopoda ("cuttle-fishes"). _ex_. calamary (_loligo_), poulpe (_octopus_), paper nautilus (_arganauta_), pearly nautilus (_nautilus_), belemnites,* orthoceratites,* ammonites.* vertebrate animals. sub-kingdom vi.--vertebrata. body composed of definite segments arranged longitudinally one behind the other; main masses of the nervous system placed dorsally; a backbone or "vertebral column" in the majority. class i. pisces ("fishes"). _ex_. lancelet** (_amphioxus_); lampreys and hag-fishes (_marsipobranchii_**); herring, salmon, perch, &c. (_teleostei_ or "bony fishes"); gar-pike, sturgeon, &c. (_ganoidei_); sharks, dog-fishes, rays, &c. (_elasmobranchii_ or "placoids"). class ii. amphibia ("amphibians"). ex. _labyrinthodontia_,* cæcilians,** newts and salamanders (_urodela_), frogs and toads (_anoura_). class iii. reptilia ("reptiles"). ex. _deinosauria_,* _pterosauria_,* _anomodontia_,* plesiosaurs (_sauropterygia_*), ichthyosaurs (_ichthyopterygia_*), tortoises and turtles (_chelonia_), snakes (_ophidia_), lizards (_lacertilia_), crocodiles (_crocodilia_). class iv. aves ("birds"). _ex_. toothed birds (_odontornithes_*); lizard-tailed birds (_archoeopteryx_*); ducks, geese, gulls, &c. (_natatores_); storks, herons, snipes, plovers, &c. (_grallatores_); ostrich, emeu, cassowary, dinornis,* Æpiornis,* &c. (_cursores_); fowls, game birds, and doves (_rasores_); cuckoos, woodpeckers, parrots, &c. (_scansores_); crows, starlings, finches, hummingbirds, swallows, &c. (_insessores_); owls, hawks, eagles, vultures (_raptores_). class v. mammalia ("quadrupeds"). _ex_. duck-mole and spiny ant-eater (_monotremata_**); kangaroos, phalangers, opossums, tasmanian devil, &c. (_marsupialia_); sloths, ant-eaters, armadillos (_edentata_); manatees and dugongs (_sirenia_); whales, dolphins, porpoises (_cetacea_); rhinoceros, tapir, horses, hippopotamus, pigs, camels and llamas, giraffes, deer, antelopes, sheep, goats, oxen (_ungulata_); hyrax (_hyracoidea_**); elephants, mastodon,* deinotherium* (_proboscidea_); seals, walrus, bears, dogs, wolves, cats, lions, tigers, &c. (_carnivora_); hares, rabbits, porcupines, beavers, rats, mice, lemmings, squirrels, marmots, &c. (_rodentia_); bats (_cheiroptera_); moles, shrew-mice, hedgehogs (_insectivora_); lemurs, spider-monkeys, macaques, baboons, apes (_quadrumana_); man (_bimana_). glossary. abdomen (lat. _abdo_, i conceal). the posterior cavity of the body, containing the intestines and others of the viscera. in many invertebrates there is no separation of the body-cavity into thorax and abdomen, and it is only in the higher _annulosa_ that a distinct abdomen can be said to exist. aberrant (lat. _aberro_, i wander away). departing from the regular type. abnormal (lat. _ab_, from; _norma_, a rule). irregular; deviating from the ordinary standard. acrodus (gr. _akros_, high; _odous_, tooth). a genus of the cestraciont fishes, so called from the elevated teeth. acrogens (gr. _akros_, high; _gennao_, i produce). plants which increase in height by additions made to the summit of the stem by the union of the bases of the leaves. acrotreta (gr. _akros_, high; _tretos_, pierced). a genus of brachiopods, so called from the presence of a foramen at the summit of the shell. actinocrinus (gr. _aktin_, a ray; _krinon_, a lily). a genus of crinoids. actinozoa (gr. _aktin_, a ray; and _zoön_, an animal). that division of the _coelenterata_ of which the sea-anemones may be taken as the type. Æglina (_Æglé_, a sea-nymph). a genus of trilobites. Æpiornis (gr. _aipus_, huge; _ornis_, bird). a genus of gigantic cursorial birds. agnostus (gr. _a_, not; _gignosko_, i know). a genus of trilobites. alces (lat. _alces_, elk). the european elk or moose. alecto (the proper name of one of the furies). a genus of _polyzoa_. alethopteris (gr. _alethes_, true; _pteris_, fern). a genus of ferns. algÆ. (lat. _alga_, a marine plant). the order of plants comprising the sea-weeds and many fresh-water plants. alveolus (lat. _alvus_, belly). applied to the sockets of the teeth. amblypterus (gr. _amblus_, blunt; _pteron_, fin). an order of ganoid fishes. ambonychia (gr. _ambon_, a boss; _onux_, claw). a genus of palæozoic bivalves. ambulacra (lat. _ambulacrum_, a place for walking). the perforated spaces or "avenues" through which are protruded the tube-feet, by means of which locomotion is effected in the _echinodermata_. ammonitidÆ. a family of tetrabranchiate cephalopods, so called from the resemblance of the shell of the type-genus, _ammonites_, to the horns of the egyptian god, jupiter-ammon. amorphozoa (gr. _a_, without; _morphe_, shape; _zoön_, animal). a name sometimes used to designate the _sponges_. amphibia (gr. _amphi_, both; _bios_, life). the frogs, newts, and the like, which have gills when young, but can always breathe air directly when adult. amphicyon (gr. _amphi_, both--implying doubt; _kuon_, dog). an extinct genus of _carnivora_. amphilestes (gr. _amphi_, both; _lestes_, a thief). a genus of jurassic mammals. amphispongia (gr. _amphi_, both; _spoggos_, sponge). a genus of silurian sponges. amphistegina (gr. _amphi_, both; _stegé_, roof). a genus of _foraminifera_. amphitherium (gr. _amphi_, both; _therion_, beast). a genus of jurassic mammals. amphitragulus (gr. _amphi_, both; dim. of _tragos_, goat). an extinct genus related to the living musk-deer. amplexus (lat. an ambrace). a genus of rugose corals. ampyx (gr. _ampux_, a wreath or wheel). a genus of trilobites. anarthropoda (gr. _a_, without; _arthros_, a joint; _pous_, foot). that division of _annulose_ animals in which there are no articulated appendages. anchitherium (gr. _agchi_, near; _therion_, beast). an extinct genus of mammals. ancyloceras (gr. _agkulos_, crooked; _ceras_, horn). a genus of _ammonitidoe_. ancylotherium (gr. _agkulos_, crooked; _therion_, beast). an extinct genus of edentate mammals. andrias (gr. _andrias_, image of man). an extinct genus of tailed amphibians. angiosperms (gr. _angeion_, a vessel; _sperma_, seed). plants which have their seeds enclosed in a seed-vessel. annelida (a gallicised form of _annulata_). the ringed worms, which form one of the divisions of the _anarthropoda_. annularia (lat. _annulus_, a ring). a genus of palæozoic plants, with leaves in whorls. annulosa (lat. _annulus_). the sub-kingdom comprising the _anarthropoda_ and the _arthropoda_ or _articulata_, in all of which the body is more or less evidently composed of a succession of rings. anomodontia (gr. _anomos_, irregular; _odous_, tooth). an extinct order of reptiles, often called _dicynodontia_. anomura (gr. _anomos_, irregular; _oura_, tail). a tribe of decapod _crustacea_, of which the hermit-crab is the type. anoplotheridÆ (gr. _anoplos_, unarmed; _ther_, beast). a family of tertiary ungulates. anoura (gr. _a_, without; _oura_, tail). the order of _amphibia_ comprising the frogs and toads, in which the adult is destitute of a tail. often, called _batrachia_. antennÆ (lat. _antenna_, a yard-arm). the jointed horns or feelers possessed by the majority of the _articulata_. antennules (dim. of _antennoe_). applied to the smaller pair of antennæ in the _crustacea_. anthracosaurus (gr. _anthrax_, coal; _saura_, lizard). a genus of labyrinthodont amphibians. anthrapalÆmon (gr. _anthrax_, coal; _paloemon_, a prawn--originally a proper name). a genus of long-tailed crustaceans from the coal-measures. antlers. properly the branches of the horns of the deer tribe (_cervidoe_), but generally applied to the entire horns. apiocrinidÆ (gr. _apion_, a pear; _krinon_, lily). a family of crinoids--the "pear-encrinites." apteryx (gr. _a_, without; _pterux_, a wing). a wingless bird of new zealand, belong to the order _cursores_. aqueous (lat. _aqua_, water). formed in or by water. arachnida (gr. _arachne_, a spider). a class of the _articulata_, comprising spiders, scorpions, and allied animals. arborescent. branched like a tree. archÆocidaris (gr. _archaios_, ancient; lat. _cidaris_, a diadem). a palæozoic genus of sea-urchins, related to the existing _cidaris_. archÆocyathus (gr. _archaios_, ancient; _kuathos_, cup). a genus of palæozoic fossils allied to the sponges. archÆopteryx (gr. _archaios_, ancient; _pterux_, a wing). the singular fossil bird which alone constitutes the order of the _saururoe_. arctocyon (gr. _arctos_, bear; _kuon_, dog). an extinct genus of carnivora. arenaceous. sandy, or composed of grains of sand. arenicolites (lat. _arena_, sand; _colo_, i inhabit). a genus founded on burrows supposed to be formed by worms resembling the living lobworms (_arenicola_). articulata (lat. _articulus_, a joint). a division of the animal kingdom, comprising insects, centipedes, spiders, and crustaceans, characterised by the possession of jointed bodies or jointed limbs. the term _arthropoda_ is now more usually employed. artiodactyla (gr. _artios_, even; _daktulos_, a finger or toe). a division of the hoofed quadrupeds (_ungulata_) in which each foot has an even number of toes (two or four). asaphus (gr. _asaphes_, obscure). a genus of trilobites. ascoceras (gr. _askos_, a leather bottle; _keras_, horn). a genus of tetrabranchiate cephalopods. asiphonate. not possessing a respiratory tube or siphon. (applied to a division of the _lamellibranchiate_ molluscs.) asteroid (gr. _aster_, a star; and _eidos_, form). star-shaped, or possessing radiating lobes or rays like a star-fish. asteroidea. an order of _echinodermata_, comprising the star-fishes, characterised by their rayed form. asterophyllites (gr. _aster_, a star; _phullon_, leaf). a genus of palæozoic plants, with leaves in whorls. astrÆidÆ (gr. _astroea_, a proper name). the family of the star-corals. astylospongia (gr. _a_, without; _stulos_, a column; _spoggos_, a sponge). a genus of silurian sponges. athyris (gr. _a_, without; _thura_, door). a genus of brachiopods. atrypa (gr. _a_, without; _trupa_, a hole). a genus of brachiopods. aves (lat. _avis_, a bird). the class of the birds. avicula (lat. a little bird). the genus of bivalve molluscs comprising the pearl-oysters. axophyllum (gr. _axon_, a pivot; _phullon_, a leaf). a genus of rugose corals. azoic (gr. _a_, without; _zoé_, life). destitute of traces of living beings. baculites (lat. _baculum_, a staff). a genus of the _ammonitidoe_. balÆna (lat. a whale). the genus of the whalebone whales. balanidÆ (gr. _balanos_, an acorn). a family of sessile _cirripedes_, commonly called "acorn-shells." batrachia (gr. _batrachos_, a frog). often loosely applied to any of the _amphibia_, but sometimes restricted to the amphibians as a class, or to the single order of the _anoura_. belemnitidÆ (gr. _belemnon_, a dart). an extinct group of dibranchiate cephalopods, comprising the belemnites and their allies. belemnoteuthis (gr. _belemnon_, a dart; _teuthis_, a cuttle-fish). a genus allied to the belemnites proper. belinurus (gr. _belos_, a dart; _oura_, tail). a genus of fossil king-crabs. bellerophon (gr. proper name). a genus of oceanic univalves (_heteropoda_). beloteuthis (gr. _belos_, a dart; _teuthis_, a cuttle-fish). an extinct genus of dibranchiate cephalopods. beyrichia (named after prof. beyrich). a genus of ostracode crustaceans. bilateral. having two symmetrical sides. bimana (lat. _bis_, twice; _manus_, a hand). the order of _mammalia_ comprising man alone. bipedal (lat. _bis_, twice; _pes_, foot). walking upon two legs. bivalve (lat. _bis_, twice; _valvoe_, folding-doors). composed of two plates or valves; applied to the shell of the _lamellibranchiata_ and _brachiopoda_, and to the carapace of certain _crustacea_. blastoidea (gr. _blastos_, a bud; and _eidos_, form). an extinct order of _echinodermata_, often called _pentremites_. brachiopoda (gr. _brachion_, an arm; _pous_, the foot). a class or the _molluscoida_, often called "lamp-shells," characterised by possessing two fleshy arms continued from the sides of the mouth. brachyura (gr. _brachus_, short; _oura_, tail). a tribe of the decapod _crustaceans_ with short tails (_i.e._, the crabs). bradypodidÆ. (gr. _bradus_, slow; _podes_, feet). the family of _edentata_ comprising the sloths. branchia (gr. _bragchia_, the gill of a fish). a respiratory organ adapted to breathe air dissolved in water. branchiate. possessing gills or branchiæ. bronteus (gr. _broné_, thunder--an epithet of jupiter the thunderer). a genus of trilobites. brontotherium (gr. _bronté_, thunder; _therion_ beast). an extinct genus of ungulate quadrupeds. brontozoum (gr. _bronté_, thunder; _zoön_, animal). a genus founded on the largest footprints of the triassic sandstones of connecticut. buccinum (lat. _buccinun_, a trumpet). the genus of univalves comprising the whelks. cainozoic (_see_ kainozoic.) calamites (lat. _calamus_, a reed). extinct plants with reed-like stems, believed to be gigantic representatives of the _equisetaceoe_. calcareous (lat. _calx_, lime). composed of carbonate of lime. calice. the little cup in which the polype of a coralligenous zoophyte (_actinozoön_) is contained. calymene (gr. _kalumené_, concealed). a genus of trilobites. calyx (lat. a cup). applied to the cup-shaped body of a _crinoid_ (_echinodermata_). camarophoria (gr. _kamara_, a chamber; _phero_, i carry). a genus of brachiopods. camelopardalidÆ. (lat. _camelus_, a camel; _pardalis_, a panther). the family of the giraffes. canine (lat. _canis_, a dog). the eye-tooth of mammals, or the tooth which is placed at or close to the præmaxillary suture in the upper jaw, and the corresponding tooth in the lower jaw. carapace. a protective shield. applied to the upper shell of crabs, lobsters, and many other _crustacea_. also the upper half of the immovable case in which the body of a chelonian is protected. carcharodon (gr. _karcharos_. rough; _odous_, tooth). a genus of sharks. cardiocarpon (gr. _kardia_, the heart; _karpos_, fruit). a genus of fossil fruit from the coal-measures. cardium (gr. _kardia_, the heart). the genus of bivalve molluscs comprising the cockles. _cardinia, cardiola_, and _cardita_ have the same derivation. carnivora (lat. _caro_, flesh; _voro_, i devour). an order of the _mammalia_. the "beasts of prey." carnivorous (lat. _caro_, flesh; _voro_, i devour). feeding upon flesh. caryocaris (gr. _karua_, a nut; _karis_, a shrimp). a genus of phyllopod crustaceans. caryocrinus (gr. _karua_, a nut; _krinon_, a lily). a genus of cystideans. caudal (lat. _cauda_, the tail). belonging to the tail. cavicornia (lat. _cavus_, hollow; _cornu_, a horn). the "hollow-horned" ruminants, in which the horn consists of a central bony "horn-core" surrounded by a horny sheath. centrum (gr. _kentron_, the point round which a circle is described by a pair of compasses). the central portion or "body" of a vertebra. cephalaspidÆ. (gr. _kephale_, head; _aspis_, shield). a family of fossil fishes. cephalic (gr. _kephale_, head). belonging to the head. cephalopoda (gr. _kephale_; and _podes_, feet). a class of the _mollusca_, comprising the cuttle-fishes and their allies, in which there is a series of arms ranged round the head. ceratiocaris (gr. _keras_, a horn; _karis_, a shrimp). a genus of phyllopod crustaceans. ceratites (gr. _keras_, a horn). a genus of _ammonitidoe_. ceratodus (gr. _keras_, a horn; _odous_, tooth). a genus of dipnoous fishes. cervical (lat. _cervix_, the neck). connected with or belonging to the region of the neck. cervidÆ (lat. _cervus_, a stag). the family of the deer. cestraphori (gr. _kestra_, a weapon; _phero_, i carry). the group of the "cestraciont fishes," represented at the present day by the port-jackson shark; so called from their defensive spines. cetacea (gr. _ketos_, a whale). the order of mammals comprising the whales and the dolphins. cetiosaurus (gr. _ketos_, whale; _saura_, lizard). a genus of deinosaurian reptiles. cheiroptera (gr. _cheir_, hand; _pteron_, wing). the mammalian order of the bats. cheirotherium (gr. _cheir_, hand; _therion_, beast). the generic name applied originally to the hand-shaped footprints of labyrinthodonts. cheirurus (gr. _cheir_, hand; _oura_, tail). a genus of trilobites. chelonia (gr. _cheloné_, a tortoise). the reptilian order of the tortoises and turtles. chonetes (gr. _choné_ or _choané_, a chamber or box). a genus of brachiopods. cidaris (lat. a diadem). a genus of sea-urchins. cladodus (gr. _klados_, branch; _odous_, tooth). a genus of fishes. clathropora (lat. _clathti_, a trellis; _porus_, a pore). a genus of lace-corals (_polyzoa_). clisiophyllum (gr. _klision_, a hut; _phullon_, leaf). a genus of rugose corals. clymenia (_clumene_, a proper name). a genus of tetrabranchiate cephalopods. coccosteus (gr. _kokkos_, berry; _osteon_, bone). a genus of ganoid fishes. cochliodus (gr. _kochlion_, a snail-shell; _odous_, tooth). a genus of cestraciont fishes. coelenterata (gr. _koilos_, hollow; _enteron_, the bowel). the sub-kingdom which comprises the _hydrozoa_ and _actinozoa_. proposed by frey and leuckhart in place of the old term _radiata_, which included other animals as well. coleoptera (gr. _koleos_, a sheath; _pteron_, wing). the order of insects (beetles) in which the anterior pair of wings are hardened, and serve as protective cases for the posterior pair of membranous wings. colossochelys (gr. _kolossos_, a gigantic statue; _chelus_, a tortoise). a huge extinct land-tortoise. comatula (gr. _koma_, the hair). the feather-star, so called in allusion to its tress-like arms. condyle (gr. _kondulos_, a knuckle). the surface by which one bone articulates with another. applied especially to the articular surface or surfaces by which the skull articulates with the vertebral column. coniferÆ (lat. _conus_, a cone; _fero_, i carry). the order of the firs, pines, and their allies, in which the fruit is generally a "cone" or "fir-apple." conularia (lat. _conulus_, a little-cone). an extinct genus of pteropods. copralites (gr. _kopros_, dung; _lithos_, stone). properly applied to the fossilised excrements of animals; but often employed to designate phosphatic concretions which are not of this nature. corallite. the corallum secreted by an _actinozoön_ which consists of a single polype; or the portion of a composite corallum which belongs to, and is secreted by, an individual polype. corallum (from the latin for red coral). the hard structures deposited in, or by the tissues of an _actinozoön_,--commonly called a "coral." coriaceous (lat. _corium_. hide). leathery. coryphodon (gr. _korus_, helmet; _odous_, tooth). an extinct genus of mammals, allied to the tapirs. cranium (gr. _kranion_, the skull). the bony or cartilaginous case in which the brain is contained. cretaceous (lat. _creta_, chalk). the formation which in europe contains white chalk as one of its most conspicuous members. crinoidea (gr. _krinon_, a lily; _eidos_, form). an order of _echinodermata_, comprising forms which are usually stalked, and sometimes resemble lilies in shape. crioceras (gr. _krios_, a ram; _keras_, a horn). a genus of _ammonitidoe_. crocodilia (gr. _krokodeilos_, a crocodile). an order of reptiles. crossopterygidÆ. (gr. _krossotos_, a fringe; _pterux_, a fin). a sub-order of ganoids in which the paired fins possess a central lobe. crustacea (lat. _crusta_, a crust). a class of articulate animals, comprising crabs, lobsters, &c., characterised by the possession of a hard shell or crust, which they cast periodically. cryptogams (gr. _kruptos_, concealed; _gamos_, marriage). a division of plants in which the organs of reproduction are obscure and there are no true flowers. ctenacanthus (gr. _kteis_, a comb; _akantha_, a thorn). a genus of fossil fishes, named from its fin-spines. ctenoid (gr. _kteis_, a comb; _eidos_, form). applied to those scales of fishes the hinder margins of which are fringed with spines or comb-like projections. cursores (lat. _curro_, i run). an order of _aves_, comprising birds destitute of the power of flight, but formed for running vigorously (_e.g._, the ostrich and emeu). cuspidate. furnished with small pointed eminences or "cusps." cyathocrinus (gr. _kuathos_, a cup; _krinon_, a lily). a genus of crinoids. cyathophyllum (gr. _kuathos_, a cup; _phullon_, a leaf). a genus of rugose corals. cycloid (gr. _kuklos_, a circle; _eidos_, form). applied to those scales of fishes which have a regularly circular or elliptical outline with an even margin. cyclophthalmus (gr. _kuklos_, a circle; _ophthalmos_, eye). a genus of fossil scorpions. cyclostomi (gr. _kuklos_, and _stoma_, mouth). sometimes used to designate the hag-fishes and lampreys, forming the order _marsipobranchii_. cyprÆa (a name of venus). the genus of univalve molluscs comprising the cowries. cyrtoceras (gr. _kurtos_. crooked; _keras_, horn). a genus of tetrabranchiate cephalopods. cystiphyllum (gr. _kustis_, a bladder; _phullon_, a leaf). a genus of rugose corals. cystoidea (gr. _kustis_, a bladder; _eidos_, form). the "globe-crinoids," an extinct order of _echinodermata_. dadoxylon (gr. _dadion_, a torch; _xulon_, wood). an extinct genus of coniferous trees. decapoda (gr. _deka_, ten; _podes_, feet). the division of _crustacea_ which have ten feet; also the family of cuttle-fishes, in which there are ten arms or cephalic processes. deciduous (lat. _decido_, i fall off). applied to parts which fall off or are shed during the life of the animal. deinosauria (gr. _deinos_, terrible; _saura_, lizard). an extinct order of reptiles. deinotherium (gr. _deinos_, terrible; _therion_, beast). an extinct genus of proboscidean mammals. dendrograptus (gr. _dendron_, tree; _grapho_, i write). a genus of graptolites. desmidiÆ. minute fresh-water plants, of a green colour, without a siliceous epidermis. diatomaceÆ (gr. _diatemno_, i sever). an order of minute plants which are provided with siliceous envelopes. dibranchiata (gr. _dis_; twice; _bragchia_, gill). the order of _cephalopoda_ (comprising the cuttle-fishes, &c.) in which only two gills are present. diceras (gr. _dis_, twice; _keras_, horn). an extinct genus of bivalve molluscs. dictyonema (gr. _diktuon_, a net; _nema_, thread). an extinct genus of _polyzoa_. dicynodontia (gr. _dis_, twice; _kuon_, dog; _odous_, tooth). an extinct order of reptiles. didymograptus (gr. _didumos_, twin; _grapho_, i write). a genus of graptolites. dimorphodon (gr. _dis_, twice; _morphé_, shape; _oduos_, tooth). a genus of pterosaurian reptiles. dinichthys (gr. _deinos_, terrible; _ichthus_, fish). an extinct genus of fishes. dinoceras (gr. _deinos_, terrible; _keras_, horn). an extinct genus of mammals. dinophis (gr. _deinos_, terrible; _ophis_, snake). an extinct genus of snakes. dinornis (gr. _deinos_, terrible; _ornis_, bird). an extinct genus of birds. diplograptus (gr. _diplos_, double; _grapho_, i write). a genus of graptolites. dipnoi (gr. _dis_, twice; _pnoé_, breath). an order of fishes, comprising the mud-fishes, so called in allusion to their double mode of respiration. diprotodon (gr. _dis_, twice; _protos_, first; _odous_, tooth). a genus of extinct marsupials. diptera (gr. _dis_, twice; _pteron_, wing). an order of insects characterised by the possession of two wings. discoid (gr. _diskos_, a quoit; _eidos_, form). shaped like a round plate or quoit. dolomite (named after m. dolomieu). magnesian limestone. dorsal (lat. _dorsum_, the back). connected with or placed upon the back. dromatherium (gr. _dromaios_, nimble; _therion_, beast). a genus of triassic mammals. dryopithecus (gr. _drus_, an oak; _pithekos_, an ape). an extinct genus of monkeys. echinodermata (gr. _echinos_; and _derma_, skin). a class of animals comprising the sea-urchins, star-fishes, and others, most of which have spiny skins. echinoidea (gr. _echinos_; and _eidos_, form). an order of _echinodermata_, comprising the sea-urchins. edentata (lat. _e_, without; _dens_, tooth). an order of _mammalia_ often called _bruta_. edentulous. toothless, without any dental apparatus. applied to the mouth of any animal, or to the hinge of the bivalve molluscs. elasmobranchii (gr. _elasma_, a plate; _bragchia_, gill). an order of fishes, including the sharks and rays. enaliosauria (gr. _enalios_, marine; _saura_, lizard), sometimes employed as a common term to designate the extinct reptilian orders of the _ichthyosauria_ and _plesiosauria_. eocene (gr. _eos_, dawn; _kainos_, new or recent). the lowest division of the tertiary rocks, in which species of existing shells are to a small extent represented. eophyton (gr. _eos_, dawn; _phuton_, a plant). a genus of cambrian fossils, supposed to be of a vegetable nature. eozoÖn (gr. _eos_, dawn; _zoön_, animal). a genus of chambered calcareous organisms found in the laurentian and huronian formations. equilateral (lat. _oequus_, equal; _latus_, side). having its sides equal. usually applied to the shells of the _brachiopoda_. when applied to the spiral shells of the _foraminifera_, it means that all the convolutions of the shell lie in the same plane. equisetaceÆ (lat. _equus_, horse; _seta_, bristle). a group of cryptogamous plants, commonly known as "horse-tails." equivalve (lat. _oequus_, equal; _valvoe_, folding-doors). applied to shells which are composed of two equal pieces or valves. errantia (lat. _erro_, i wander). an order of _annelida_, often called _nereidea_, distinguished by their great locomotive powers. euomphalus (gr. _eu_, well; _omphalos_, navel). an extinct genus of univalve molluscs. eurypterida (gr. _eurus_, broad; _pteron_, wing). an extinct sub-order of _crustacea_. exogyra (gr. _exo_, outside; _guros_, circle). an extinct genus of oysters. fauna (lat. _fauni_, the rural deities of the romans). the general assemblage of the animals of any region or district. favosites (lat. _favus_, a honeycomb). a genus of tabulate corals. fenestellidÆ. (lat. _fenestella_, a little window). the "lace-corals," a group of palæozoic polyzoans. filices (lat. _filix_, a fern). the order of cryptogamic plants comprising the ferns. filiform (lat. _filum_, a thread; _forma_, shape). thread-shaped. flora (lat. _flora_, the goddess of flowers). the general assemblage of the plants of any region or district. foraminifera (lat. _foramen_, an aperture; _fero_, i carry). an order of protozoa, usually characterised by the possession of a shell perforated by numerous pseudopodial apertures. frugivorous (lat. _frux_, fruit; _voro_, i devour). living upon fruits. fucoids (lat. _fucus_, sea-weed; gr. _eidos_, likeness). fossils, often of an obscure nature, believed to be the remains of sea-weeds. fusulina (lat. _fusus_, a spindle). an extinct genus of _foraminifera_. ganoid (gr, _ganos_, splendour, brightness). applied to those scales or plates which are composed of an inferior layer of true bone covered by a superior layer of polished enamel. ganoidei. an order of fishes. gasteropoda (gr. _gaster_, stomach; _pous_, foot). the class of the mollusca comprising the ordinary univalves, in which locomotion is usually effected by a muscular expansion of the under surface of the body (the "foot"). globigerina (lat. _globus_, a globe; _gero_, i carry). a genus of _foraminifera_. glyptodon (gr. _glupho_, i engrave; _odous_, tooth). an extinct genus of armadillos, so named in allusion to the fluted teeth. goniatites (gr. _gonia_, angle). a genus of tetrabranchiate cephalopods. grallatores (lat. _gralloe_, stilts). the order of the long-legged wading birds. graptolitidÆ. (gr. _grapho_, i write; _lithos_, stone). an extinct sub-class of the _hydrozoa_. gymnosperms (gr. _gumnos_, naked; _sperma_, seed). the conifers and cycads, in which the seed is not protected within a seed-vessel. halitherium (gr. _hals_, sea; _therion_, beast). an extinct genus of sea-cows (_sirenia_). hamites (lat. _hamus_, a hook). a genus of the _ammonitidoe_. heliophyllum (gr. _helios_, the sun; _phullon_, leaf). a genus of rugose corals. helladotherium (gr. _hellas_, greece; _therion_, beast). an extinct genus of ungulate mammals. hemiptera (gr. _hemi_, and _pteron_, wing). an order of insects in which the anterior wings are sometimes "hemelytra." hesperornis (gr. _hesperos_, the evening star; _ornis_, bird). an extinct genus of birds. heterocercal (gr. _heteros_, diverse; _kerkos_, tail). applied to the tail of fishes when it is unsymmetrical, or composed of two unequal lobes. heteropoda (gr. _heteros_, diverse; _podes_, feet). an aberrant group of the gasteropods, in which the foot is modified so as to form a swimming organ. hipparion (gr. _hipparion_, a little horse). an extinct genus of _equidoe_. hippopotamus (gr. _hippos_, horse; _potamos_, river). a genus of hoofed quadrupeds--the "river-horses." hippuritidÆ. (gr. _hippos_, horse; _oura_, tail). an extinct family of bivalve molluscs. holoptychius (gr. _holos_, whole; _ptucé_, wrinkle). an extinct genus of ganoid fishes. holostomata (gr. _holos_, whole; _stoma_, mouth). a division of _gasteropodous molluscs_, in which the aperture of the shell is rounded, or "entire." holothuroidea (gr. _holothourion_, and _eidos_, form). an order of _echinodermata_ comprising the trepangs. homocercal (gr. _homos_, same; _kerkol_, tail). applied to the tail of fishes when it is symmetrical, or composed of two equal lobes. hybodunts (gr. _hubos_, curved; _odous_, tooth). a group of fishes of which _hybodus_ is the type-genus. hydroida (gr. _hudra_; and _eidos_, form). the sub-class of the _hydrozoa_, which comprises the animals most nearly allied to the hydra. hydrozoa (gr. _hudra_; and _zoön_, animal). the class of the _coelenterata_ which comprises animals constructed after the type of the hydra. hymenoptera (gr. _humen_, a membrane; _pteron_, a wing). an order of insects (comprising bees, ants, &c.) characterised by the possession of four membranous wings. ichthyodorulite (gr. _ichthus_, fish; _dorus_, spear; _lithos_, stone). the fossil fin-spine of fishes. ichthyopterygia (gr. _ichthus_; _pterux_, wing). an extinct order of reptiles. ichthyornis (gr. _ichthus_, fish; _ornis_, bird). an extinct genus of birds. ichthyosauria (gr. _ichthus_; _saura_, lizard). synonymous with _ichthyopterygia_. iguanodon (_iguana_, a living lizard; gr. _odous_, tooth). a genus of deinosaurian reptiles. incisor (lat. _incido_, i cut). the cutting teeth fixed in the intermaxillary bones of the _mammalia_, and the corresponding teeth in the lower jaw. inequilateral. having the two sides unequal, as in the case of the shells of the ordinary bivalves (_lamellibranchiata_). when applied to the shells of the _foraminifera_, it implies that the convolutions of the shell do not lie in the same plane, but are obliquely wound round an axis. inequivalve. composed of two unequal pieces or valves. inoceramus (gr. _is_, a fibre; _keramos_, an earthen vessel). an extinct genus of bivalve molluscs. insecta (lat. _inseco_, i cut into). the class of articulate animals commonly known as insects. insectivora (lat. _insectum_, an insect; _voro_, i devour). an order of mammals. insectivorous. living upon insects. insessores (lat. _insedeo_, i sit upon). the order of the perching birds, often called _passeres_. interambulacra. the rows of plates in an _echinoid_ which are not perforated for the emission of the "tube-feet." intermmaxillÆ or prÆmaxillÆ. the two bones which are situated between the two superior maxillæ in _vertebrata_. in man, and some monkeys, the præmaxillæ anchylose with the maxillæ, so as to be irrecognisable in the adult. invertebrata (lat. _in_, without; _vertebra_, a bone of the back). animals without a spinal column or backbone. isopoda. (gr. _isos_, equal; _podes_, feet). an order of _crustacea_ in which the feet are like one another and equal. kainozoic (gr. _kainos_, recent; _zoe_, life). the tertiary period in geology comprising those formations in which the organic remains approximate more or less closely to the existing fauna and flora. labyrinthodontia (gr. _laburinthos_, a labyrinth; _odous_, tooth). an extinct order of _amphibia_, so called from the complex microscopic structure of the teeth. lacertilia (lat. _lacerta_, a lizard). an order of _reptilia_ comprising the lizards and slow-worms. lamellibranchiata (lat. _lamella_, a plate; gr. _bragchia_, gill). the class of _mollusca_ comprising the ordinary bivalves, characterised by the possession of lamellar gills. lepidodendron (gr. _lepis_, a scale; _dendron_, a tree). a genus of extinct plants, so named from the scale-like scars upon the stem left by the falling off of the leaves. lepidoptera (gr. _lepis_, a scale; _pteron_, a wing). an order of insects, comprising butterflies and moths, characterised by possessing four wings which are usually covered with minute scales. lepidosiren (gr. _lepis_, a scale; _seiren_, a siren--the generic name of the mud-eel or _siren lacertina_). a genus of dipnoous fishes, comprising the "mud-fishes." lepidostrobus (gr. _lepis_, a scale; _strobilos_, a fir-cone). a genus founded on the cones of _lepidodendron_. leptÆna (gr. _leptos_. slender). a genus of brachiopods. lingula (lat. _lingula_, a little tongue). a genus of brachiopods. lycopodiaceÆ (gr. _lupos_, a wolf; _pous_, foot). the group of cryptogamic plants generally known as "club-mosses." machÆracanthus (gr. _machaira_, a sabre; _acantha_, thorn or spine). an extinct genus of fishes. machairodus (gr. _machaira_, a sabre; _odous_, tooth). an extinct genus of carnivora. macrotherium (gr. _makros_, long; _therion_. beast). an extinct genus of edentata. macrura (gr. _makros_, long; _oura_, tail). a tribe of decapod _crustaceans_ with long tails (e.g., the lobster, shrimp, &c.) mammalia (lat. _mamma_, the breast). the class of vertebrate animals which suckle their young. mandible (lat. _mandibulum_, a jaw). the upper pair of jaws in insects; also applied to one of the pairs of jaws in _crustacea_ and spiders, to the beak of cephalopods, the lower jaw of vertebrates, &c. mantle. the external integument of most of the mollusca, which is largely developed, and forms a cloak in which the viscera are protected. technically called the "pallium." manus (lat. the hand). the hand of the higher vertebrates. marsipobranchii (gr. _marsipos_, a pouch; _bragchia_, gill). the order of fishes comprising the hag-fishes and lampreys, with pouch-like gills. marsupialia (lat. _marsupium_, a pouch). an order of mammals in which the females mostly have an abdominal pouch in which the young are carried. mastodon (gr. _mastos_, nipple; _odous_, tooth). an extinct genus of elephantine mammals. megalonyx (gr. _megas_, great; _onux_, nail). an extinct genus of edentate mammals. megalosaurus (gr. _megas_, great; _saura_, lizard). a genus of deinosaurian reptiles. megatherium (gr. _megas_, great; _therion_, beast). an extinct genus of edentata. mesozoic (gr. _mesos_, middle; and _zoe_, life). the secondary period in geology. microlestes (gr. _mikros_, little; _lestes_, thief). an extinct genus of triassic mammals. millepora (lat. _mille_, one thousand; _porus_, a pore). a genus of "tabulate corals." miocene (gr. _meion_, less; _kainol_, new). the middle tertiary period. molars (lat. _mola_, a mill). the "grinders" in man, or the teeth in diphyodont mammals which are not preceded by milk-teeth. mollusca (lat. _mollis_, soft). the sub-kingdom which includes the shell-fish proper, the _polyzoa_, the _tunicata_, and the lamp-shells; so called from the generally soft nature of their bodies. molluscoida (_mollusca_; gr. _eidos_, form). the lower division of the _mollusca_, comprising the _polyzoa, tunicata_, and _brachiopoda_. monograptus (gr. _monos_, single; _grapho_, i write). a genus of graptolites. mylodon (gr. _mulos_, a mill; _odous_, tooth). an extinct genus of edentate mammals. myriapoda or myriopoda (gr. _murios_, ten thousand; _podes_, feet). a class of _arthropoda_ comprising the centipedes and their allies, characterised by their numerous feet. natatores (lat. _nare_, to swim). the order of the swimming birds. natatory (lat. _nare_, to swim). formed for swimming. nautiloid. resembling the shell of the _nautilus_ in shape. nervures (lat. _nervus_, a sinew). the ribs which support the membranous wings of insects. neuroptera (gr. _neuron_, a nerve; _pteron_, a wing). an order of insects characterised by four membranous wings with numerous reticulated nervures (_e.g._, dragon-flies). neuropteris (gr. _neuron_, a nerve; _pteris_, a fern). an extinct genus of ferns. nothosaurus (gr. _nothos_, spurious; _saura_, lizard). a genus of _plesiosaurian_ reptiles. notochord (gr. _notos_, back; _chorde_, string). a cellular rod which is developed in the embryo of vertebrates immediately beneath the spinal cord, and which is usually replaced in the adult by the vertebral column. often it is spoken of as the "chorda dorsalis." nudibranchiata (lat. _nudus_, naked; and gr. _bragchia_, gill). an order of the _gasteropoda_ in which the gills are naked. nummulina (lat. _nummus_, a coin). a genus of _foraminifera_, comprising the coin-shaped "nummulites." obolella (lat. dim. of _obolus_, a small coin). an extinct genus of brachiopods. occipital. connected with the _occiput_, or the back part of the head. oceanic. applied to animals which inhabit the open ocean (= pelagic). odontopteryx (gr. _oduos_, tooth; _pterux_, wing). an extinct genus of birds. odontornithes (gr. _oduos_, tooth; _ornis_, bird). the extinct order of birds, comprising forms with distinct teeth in sockets. oligocene (gr. _oligos_, few; _kainos_, new). a name used by many continental geologists as synonymous with the lower miocene. ophidia (gr. _ophis_, a serpent). the order of reptiles comprising the snakes. ophiuroidea (gr. _ophis_, snake; _oura_, tail; _eidos_, form). an order of _echinodermata_, comprising the brittle-stars and sand-stars. ornithoscelida (gr. _ornis_, bird; _skelos_, leg). applied by huxley to the deinosaurian reptiles, together with the genus _compsognathus_, on account of the bird-like character of their hind-limbs. orthis (gr. _orthos_, straight). a genus of brachiopods, named in allusion to the straight hinge-line. orthoceratidÆ (gr. _orthos_, straight; _keras_, horn). a family of the _nautilidoe_, in which the shell is straight, or nearly so. orthoptera (gr. _orthos_, straight; _pteron_, wing). an order of insects. osteolepis (gr. _osteon_, bone; _lepis_, scale). an extinct genus of ganoid fishes. ostracoda (gr. _ostrakon_, a shell). an order of small crustaceans which are enclosed in bivalve shells. otodus (gr. _ota_, ears; _odous_, tooth). an extinct genus of sharks. oudenodon (gr. _ouden_, none; _odous_, tooth). a genus of dicynodont reptiles. ovibus (lat. _ovis_, sheep; _bos_, ox). the genus comprising the musk-ox. pachydermata (gr. _pachus_, thick; _derma_, skin). an old mammalian order constituted by cuvier for the reception of the rhinoceros, hippopotamus, elephant, &c. palÆaster (gr. _palaios_, ancient; _aster_, star). an extinct genus of star-fishes. palÆocaris (gr. _palaios_, ancient; _karis_, shrimp). an extinct genus of decapod crustaceans. palÆolithic (gr. _palaios_, ancient; _lithos_, stone). applied to the rude stone implements of the earliest known races of men, to the men who made these implements, or to the period at which they were made. palÆontology (gr. _palaios_, ancient; and _logos_, discourse). the science of fossil remains or of extinct organised beings. palÆophis (gr. _palaios_, ancient; _ophis_, serpent). an extinct genus of snakes. palÆosaurus (gr. _palaios_, ancient; _saura_, lizard). a genus of thecodont reptiles. palÆotheridÆ. (gr. _palaios_, ancient; _ther_, beast). a group of tertiary ungulates. palÆozoic (gr. _palaios_, ancient; and _zoe_, life). applied to the oldest of the great geological epochs. paradoxides (lat. _paradoxus_, marvellous). a genus of trilobites. patagium (lat. the border of a dress). applied to the expansion of the integument by which bats, flying squirrels, and other animals support themselves in the air. pecopteris (gr. _peko_, i comb; _pteris_, a fern). an extinct genus of ferns. pecten (lat. a comb). the genus of bivalve molluscs comprising the scallops. pectoral (lat. _pectus_, chest). connected with, or placed upon, the chest. pentacrinus (gr. _penta_, five; _krinon_, lily). a genus of crinoids in which the column is five-sided. pentamerus (gr. _penta_, five; _meros_, part). an extinct genus of brachiopods. pentremites (gr. _penta_, five; _trema_, aperture). a genus of _blastoidea_, so named in allusion to the apertures at the summit of the calyx. perennibranchiata (lat. _perennis_, perpetual; gr. _bragchia_, gill). applied to those amphibia in which the gills are permanently retained throughout life. perissodactyla (gr. _perissos_, uneven; _daktulos_, finger). applied to those hoofed quadrupeds (_ungulata_) in which the feet have an uneven number of toes. petaloid. shaped like the petal of a flower. phacops (gr. _phaké_, a lentil; _ops_, the eye). a genus of trilobites. phalanges (gr. _phalanx_, a row). the small bones composing the digits of the higher _vertebrata_. normally each digit has three phalanges. phanerogams (gr. _phaneros_, visible; _gamos_, marriage). plants which have the organs of reproduction conspicuous, and which bear true flowers. pharyngobranchii (gr. _pharugx_, pharynx; _bragchia_, gill). the order of fishes comprising only the lancelet. phascolotherium (gr. _phaskolos_, a pouch; _therion_, a beast). a genus of oolitic mammals. phragmacone (gr. _phragma_, a partition; and _konos_, a cone). the chambered portion of the internal shell of a _belemnite_. phyllopoda (gr. _phullon_, leaf; and _pous_, foot). an order of _crustacea_. pinnate (lat. _pinna_, a feather). feather-shaped; or possessing lateral processes. pinnigrada (lat. _pinna_, a feather; _gradior_, i walk). the group of _carnivora_, comprising the seals and walruses, adapted for an aquatic life. often called _pinnipedia_. pinnulÆ. (lat. dim. of _pinna_). the lateral processes of the arms of _crinoids_. pisces (lat. _piscis_, a fish). the class of vertebrates comprising the fishes. placoid (gr. _plax_, a plate; _eidos_, form). applied to the irregular bony plates, grains, or spines which are found in the skin of various fishes (_elasmobranchii_). plagiostomi (gr. _plagios_, transverse; _stoma_, mouth). the sharks and rays, in which the mouth is transverse, and is placed on the under surface of the head. platyceras (gr. _platus_, broad; _keras_, horn). a genus of univalve molluscs. platycrinus (gr. _platus_, broad; _krinom_, lily). a genus of crinoidea. platyrhina (gr. _platus_, broad; _rhines_, nostrils). a group of the _quadrumana_. platysomus (gr. _platus_, wide; _soma_, body). a genus of ganoid fishes. pleistocene (gr. _pleistos_, most; _kainos_, new). often used as synonymous with "post-pliocene." pleurotomaria (gr. _pleura_, the side; _tomé_, notch). a genus of univalve shells. pliocene (gr. _pleion_, more; _kainos_, new). the later tertiary period. pliopithecus (gr. _pleion_, more; _pithekos_, ape). an extinct genus of monkeys. pliosaurus (gr. _pleion_, more; _saura_, lizard). a genus of plesiosaurian reptiles. polycystina (gr. _polus_, many; and _kustis_, a cyst). an order of _protozoa_ with foraminated siliceous shells. polypary. the hard chitinous covering secreted by many of the _hydrozoa_. polype (gr. _polus_, many; _pous_, foot). restricted to the single individual of a simple _actinozoön_, such as a sea-anemone, or to the separate zooids of a compound _actinozoön_. often applied indiscriminately to any of the _coelenterata_, or even to the polyzoa. polypora (gr. _polus_, many; _poros_, a passage). a genus of lace-corals (_fenestellidoe_). polythalamous (gr. _polus_; and _thalamos_, chamber). having many chambers; applied to the shells of _foraminifera_ and _cephalopoda_. polyzoa (gr. _polus_; and _zoön_, animal). a division of the _molluscoida_ comprising compound animals, such as the sea-mat--sometimes called _bryozoa_. porifera (lat. _porus_, pore; and _fero_, i carry). sometimes used to designate the _foraminifera_, or the _sponges_. prÆmolars (lat. _proe_, before; _molares_, the grinders). the molar teeth of mammals which succeed the molars of the milk-set of teeth. in man, the bicuspid teeth. proboscidea (lat. _proboscis_, the snout). the order of mammals comprising the elephants. procoelous (gr. _pro_, before; _koilos_, hollow). applied to vertebræ the bodies of which are hollow or concave in front. producta (lat. _productus_, drawn out or extended). an extinct genus of brachiopods, in which the shell is "eared," or has its lateral angles drawn out. protichnites (gr. _protos_, first; _ichnos_, footprint). applied to certain impressions in the potsdam sandstone of north america, believed to have been produced by large crustaceans. protophyta (gr. _protos_; and _phuton_, plant). the lowest division of plants. protoplasm (gr. _protos_; and _plasso_ i mould). the elementary basis of organised tissues. sometimes used synonymously for the "sarcode" of the _protozoa_. protorosaurus or proterosaurus (gr. _protos_, first; _orao_, i see or discover; _saura_, lizard: or _proteros_, earlier; _saura_, lizard). a genus of permian lizards. protozoa (gr. _protos_; and _zoön_, animal). the lowest division of the animal kingdom. psammodus (gr. _psammos_, sand; _odous_, tooth). an extinct genus of cestraciont sharks. pseudopodia (gr. _pseudos_, falsity; and _pous_, foot). the extensions of the body-substance which are put forth by the _rhizopoda_ at will, and which serve for locomotion and prehension. psilophyton (gr. _psilos_, bare; _phuton_, plant). an extinct genus of lycopodiaceous plants. pteranodon (gr. _pteron_, wing; _a_, without; _odous_, tooth). a genus of pterosaurian reptiles. pteraspis (gr. _pteron_, wing; _aspis_, shield). a genus of ganoid fishes. pterichthys (gr. _pteron_, wing; _ichthus_, fish). a genus of ganoid fishes. pterodactylus (gr. _pteron_, wing; _daktulos_, finger). a genus of pterosaurian reptiles. pteropoda (gr. _pteron_, wing; and _pous_, foot). a class of the _mollusca_ which swim by means of fins attached near the head. pterosauria (gr. _pteron_, wing; _saura_, lizard). an extinct order of reptiles. ptilodictya (gr. _ptilon_, a feather; _diktuon_, a net). an extinct genus of _polyzoa_. ptychoceras (gr. _ptucé_, a fold; _keras_, a horn). a genus of _ammonitidoe_. pulmonate. possessing lungs. pyriform (lat. _pyrus_, a pear; and _forma_, form). pear-shaped. quadrumana (lat. _quatuor_, four; _manus_, hand). the order of mammals comprising the apes, monkeys, baboons, lemurs, &c. radiata (lat. _radius_, a ray). formerly applied to a large number of animals which are now placed in separate sub-kingdoms (e.g., the _coelenterata_, the _echinodermata_, the _infusoria_, &c.) radiolaria (lat. _radius_, a ray). a division of _protozoa_. ramus (lat. a branch). applied to each half or branch of the lower jaw, or mandible, of vertebrates. raptores (lat. _rapto_, i plunder). the order of the birds of prey. rasores (lat. _rado_, i scratch). the order of the scratching birds (fowls. pigeons, &c.) receptaculites (lat. _receptaculum_, a storehouse). an extinct genus of protozoa. reptilia (lat. _repto_, i crawl). the class of the _vertebrata_ comprising the tortoises, snakes, lizards, crocodiles, &c. retepora (lat. _reté_, a net; _porus_, a pore). a genus of lace-corals (_polyzoa_). rhamphorhynchus (gr. _rhamphos_, beak; _rhugchos_, nose). a genus of pterosaurian reptiles. rhinoceros (gr. _rhis_, the nose; _keras_, horn). a genus of hoofed quadrupeds. rhizopoda (gr. _rhiza_, a root; and _pous_, foot). the division of _protozoa_ comprising all those which are capable of emitting pseudopodia. rhyncholites (gr. _rhugchos_, beak; and _lithos_, stone). beak-shaped fossils consisting of the mandibles of _cephalopoda_. rhynchonella (gr. _rhugchos_, nose or beak). a genus of brachiopods. rodentia (lat. _rodo_, i gnaw). an order of the mammals; often called _glires_ (lat. _glis_, a dormouse). rotalia (lat. _rota_, a wheel). a genus of _foraminifera_. rugosa (lat. _rugosus_, wrinkled). an order of corals. ruminantia (lat. _ruminor_, i chew the cud). the group of hoofed quadrupeds (_ungulata_) which "ruminate" or chew the cud. sarcode (gr. _sarx_, flesh; _eidos_, form). the jelly-like substance of which the bodies of the _protozoa_ are composed. it is an albuminous body containing oil-granules, and is sometimes called "animal protoplasm." sauria (gr. _saura_, a lizard). any lizard-like reptile is often spoken of as a "saurian;" but the term is sometimes restricted to the crocodiles alone, or to the crocodiles and lacertilians. sauropterygia (gr. _sauro_; _pterux_, wing). an extinct order of reptiles, called by huxley _plesiosauria_, from the typical genus _plesiosaurus_. saururÆ (gr. _saura_; _oura_, tail). the extinct order of birds comprising only the _archoeopteryx_. scansores (lat. _scando_, i climb). the order of the climbing birds (parrots, woodpeckers, &c.) scaphites (lat. _scapha_, a boat). a genus of the _ammonitidoe_. scolithus (gr. _skolex_, a worm; _lithos_, a stone). the vertical burrows of sea-worms in rocks. scuta (lat. _scutum_, a shield). applied to any shield-like plates; especially to those which are developed in the integument of many reptiles. selachia or selachii (gr. _selachos_, a cartilaginous fish, probably a shark). the sub-order of _elasmobranchii_ comprising the sharks and dog-fishes. sepiostaire. the internal shell of the sepia, commonly known as the "cuttle-bone." septa. partitions. serpentiform. resembling a serpent in shape. sertularida (lat. _sertum_, a wreath). an order of _hydrozoa_. sessile (lat. _sedo_, i sit). not supported upon a stalk or peduncle; attached by a base. sethÆ (lat. bristles). bristles or long stiff hairs. sigillarioids (lat. _sigilla_, little images). a group of extinct plants of which _sigillaria_ is the type, so called from the seal-like markings on the bark. siliceous (lat. _silex_, flint). composed of flint. sinistral (lat. _sinistra_, the left hand). left-handed; applied to the direction of the spiral in certain shells, which are said to be "reversed." siphon (gr. a tube). applied to the respiratory tubes in the _mollusca_; also to other tubes of different functions. siphonia (gr. _siphon_, a tube). a genus of fossil sponges. siphonostomata (gr. _siphon_; and _stoma_, mouth). the division of _gasteropodous molluscs_ in which the aperture of the shell is not "entire," but possesses a notch or tube for the emission of the respiratory siphon. siphuncle (lat. _siphunculus_, a little tube). the tube which connects together the various chambers of the shell of certain _cephalopoda_ (_e.g._, the pearly nautilus). sirenia (gr. _seiren_. a mermaid). the order of _mammalia_ comprising the dugongs and manatees. sivatherium (_siva_, a hindoo deity; gr. _therion_, beast). an extinct genus of hoofed quadrupeds. solidungula (lat. _solidus_, solid; _ungula_, a hoof). the group of hoofed quadrupeds comprising the horse, ass, and zebra, in which each foot has only a single solid hoof. often called _solipedia_. sphenopteris (gr. _sphen_, a wedge; _pteris_, a fern). an extinct genus of ferns. spicula (lat. _spicidum_, a point). pointed needle-shaped bodies. spirifera (lat. _spira_, a spire or coil; _fero_, i carry). an extinct genus of brachiopods, with large spiral supports for the "arms." spirorbis (lat. _spira_, a spire; _orbis_, a circle). a genus of tube-inhabiting annelides, in which the shelly tube is coiled into a spiral disc. spongida (gr. _spoggos_, a sponge). the division of _protozoa_ commonly known as sponges. stalactites (gr. _stalasso_, i drop). icicle-like encrustations and deposits of lime, which hang from the roof of caverns in limestone. stalagmite (gr. _stalagma_, a drop). encrustations of lime formed on the floor of caverns which are hollowed out of limestone. stigmaria (gr. _stigma_, a mark made with a pointed instrument). a genus founded on the roots of various species of _sigillaria_. stratum (lat. _stratus_, spread out; or _stratum_, a thing spread out). a layer of rock. stromatopora (gr. _stroma_, a thing spread out; _paras_, a passage or pore). a palæozoic genus of _protozoa_. strophohena (gr. _strophao_, i twist; _mené_, moon). an extinct genus of brachiopods. sub-calcareous. somewhat calcareous. sub-central. nearly central, but not quite. suture (lat. _suo_, i sew). the line of junction of two parts which are immovably connected together. applied to the line where the whorls of a univalve shell join one another; also to the lines made upon the exterior of the shell of a chambered _cephalopod_ by the margins of the septa. syringopora (gr. _surigx_, a pipe; _poros_, a pore). a genus of tabulate corals. tabulÆ. (lat. _tabula_, a tablet). horizontal plates or floors found in some corals, extending across the cavity of the "theca" from side to side. tegumentary (lat. _tegumentum_, a covering). connected with the integument or skin. teleosaurus (gr. _teleios_, perfect; _saura_, lizard). an extinct genus of crocodilian reptiles. teleostei (gr. _teleios_, perfect; _osteon_, bone). the order of the "bony fishes." telson (gr. a limit). the last joint in the abdomen of _crustacea_; variously regarded as a segment without appendages, or as an azygous appendage. tentaculites (lat. _tentaculum_, a feeler). a genus of _pteropoda_. terebratula (lat. _terebratus_, bored or pierced). a genus of _brachiopoda_, so called in allusion to the perforated beak of the ventral valve. test (lat. _testa_, shell). the shell of _mollusca_, which are for this reason sometimes called "_testacea_;" also, the calcareous case of _echinoderms_; also, the thick leathery outer tunic in the _tunicata_. testaceous. provided with a shell or hard covering. testudinidÆ (lat. _testudo_, a tortoise). the family of the tortoises. tetrabranchiata (gr. _tetra_, four; _bragchia_, gill). the order of _cephalopoda_ characterised by the possession of four gills. textularia. (lat. _textilis_, woven). a genus of _foraminifera_. theca (gr. _theké_, a sheath). a genus of pteropods. thecodontosaurus (gr. _theké_, a sheath; _odous_, tooth; _saura_, lizard). a genus of "thecodont" reptiles, so named in allusion to the fact that the teeth are sunk in distinct sockets. theriodont (gr. _therion_, a beast; _odous_, tooth). a group of reptiles so named by owen in allusion to the mammalian character of their teeth. thorax (gr. a breastplate). the region of the chest. thylacoleo (gr. _thulakos_, a pouch; _leo_, a lion). an extinct genus of marsupials. trigonia (gr. _treis_, three; _gonia_, angle). a genus of bivalve molluscs. trigonocarpon (gr. _treis_, three; _gonia_. angle; _karpos_, fruit). a genus founded on fossil fruits of a three-angled form. trilobita (gr. _treis_, three; _lobos_, a lobe). an extinct order of _crustaceans_. trinucleus (lat. _tris_, three; _nucleus_, a kernel). a genus of trilobites. trogontherium (gr. _trogo_, i gnaw; _therion_, beast). an extinct genus of beavers. tubicola (lat. _tuba_, a tube; and _colo_, i inhabit). the order of _annelida_ which construct a tubular case in which they protect themselves. tubicolous. inhabiting a tube. tunicata (lat. _tunica_, a cloak). a class of _molluscoida_ which are enveloped in a tough leathery case or "test." turbinated (lat. _turbo_, a top). top-shaped; conical with a round base. turrilites (lat, _turris_, a tower). a genus of the _ammonitidoe_. umbo (lat. the boss of a shield). the beak of a bivalve shell. unguiculate (lat. _unguis_, nail). furnished with claws. ungulata (lat. _ungula_, hoof). the order of mammals comprising the hoofed quadrupeds. ungulate. furnished with expanded nails constituting hoofs. unilocular (lat. _unus_, one; and _loculus_. a little purse). possessing a single cavity or chamber. applied to the shells of _foraminifera_ and _mollusca_. univalve (lat. _unus_, one; _valvoe_, folding-doors). a shell composed of a single piece or valve. urodela (gr. _oura_, tail; _delos_, visible). the order of the tailed amphibians (newts, &c.) ventral (lat. _venter_, the stomach). relating to the inferior surface of the body. ventriculites (lat. _ventriculum_, a little stomach). a genus of siliceous sponges. vermiform (lat. _vermis_, worm; and _forma_, form). worm-like. vertebra (lat. _verto_, i turn). one of the bony segments of the vertebral column or backbone. vertebrata (lat. _vertebra_, a bone of the back, from _vertere_, to turn). the division of the animal kingdom roughly characterised by the possession of a backbone. vesicle (lat. _vesica_, a bladder). a little sac or cyst. whorl. the spiral turn of a univalve shell. xiphosura (gr. _xiphos_, a sworn; and _oura_, tail). an order of _crustacea_, comprising the _limuli_ or king-crabs, characterised by their long sword-like tails. xylobius (gr. _xulon_, wood; _bios_, life). an extinct genus of myriapods, named in allusion to the fact that the animal lived on decaying wood. zaphrentis (proper name). a genus of rugose corals. zeuglodontidÆ. (gr. _zeuglé_, a yoke; _odous_, a tooth). an extinct family of cetaceans, in which the molar teeth are two-fanged, and look as if composed of two parts united by a neck. zoophyte (gr. _zoön_, animal; _phuton_, plant). loosely applied to many plant-like animals, such as sponges, corals, sea-anemones, sea-mats, &c. index. acadian group. _acer_. _acervularia_. _acidaspis_. acorn-shells. _acroculia_. _acrodus; nobilis_. _acrotreta_. _acroura_. _actinocrinus_. _Æglina_. _Æpiornis_. _agnostus; rex_. _alces malchis_. _alecto_. _alethopteris_. _algoe_ (_see_ sea-weeds). alligators. _alnus_. _amblypterus; macropterus_. _ambonychia_. _ammonites; humpresianus; bifrons_. _ammonitidoe_. _amphibia_; of the carboniferous; of the permian; of the trias; of the jurassic; of the miocene. _amphicyon_. _amphilestes_. _amphispongia_. _amphistegina_. _amphitherium; prevostii_. _amphitragulus_. _amplexus; coralloides_. _ampyx_. _anachytes_. _anchitherium_. _ancyloceras; matheronianus_. _ancylotherium pentelici_. _andrias scheuchzeri_. _angiosperms_. animal kingdom, divisions of. _anisopus_. _annelida_, of the cambrian period; of the lower silurian; of the upper silurian; of the devonian; of the carboniferous. _annularia_. _anomodontia_. _anoplotheridoe_. _anoplotherium; commune_. ant-eaters. antelopes. _anthracosaurus russelli_. _anthrapaloemon gracilis_. _antilocapra_. _antilope quadricornis_. antwerp crag. apes. _apiocrinus_. _apteryx_. aqueous rocks. _arachnida_ of the coal-measures. aralo-caspian beds. _araucaria_. _araucarioxylon_. _arca; antiqua_. _archoeocidaris_. _archoeocyathus_. _archoeopteryx; macrura_. _archoeospoerinoe_. _archimedes; wortheni_. _archiulus_. arctic regions, miocene flora of. _arctocyon_. arenaceous rocks. _arenicolites; didymus_. arenig rocks. argillaceous rocks. armadillos. _artiodactyle ungulates_. _asaphus; tyrannus_. _ascoceras_. _aspidella_. _aspidura loricata_. _astarte borealis_. _asterophyllites_. _asterosteus_. _astroeidoe_. _astroeospongia_. _astylospongia; proemorsa_. _athyris; subtilita_. atlantic ooze. _atrypa; congesta; hemispoerica; reticularis_. auger-shells. aurochs. aves (_see_ birds). _avicula; cantorta; socialis_. "avicula contorta beds". _aviculidoe_. _aviculopecten_. _axophyllum_. aymestry limestone. azoic rocks. _baculites; anceps_. bagshot and bracklesham beds. _bakewellia_. _baloena_. bala group. bala limestone. _balanidoe_. _banksia_. barbadoes earth. barnacles. bath oolite. bats. bears. beaver. beetles. _belemnitella mucronata_. _beleminites; canaliculatus_. _belemnitidoe_. _belemnoteuthis_. _belinurus_. _bellerophon; argo_. _belodon; carolinensis_. _belosepia_. _beloteuthis subcostata_. bembridge beds. _beryx; lewesiensis_. _beyrichia; complicata_. bird's-eye limestone. birds, of the trias; of the jurassic; of the cretaceous; of the eocene; of the post-pliocene. _bison priscus_. bituminous schists of caithness. bivalves (_see_ lamellibranchiata). black-lead (_see_ graphite). black-river limestone. _blastoidea_; of the devonian; of the carboniferous. _boidoe_. bolderberg beds. bone-bed, of the upper ludlow; of the trias. bony fishes (_see_ teleostean fishes). _bos primigenius; _taurus_. boulder-clay. _bourgueticrinus_. bovey-tracy beds. _brachiopoda_; of the cambrian rocks; of the lower silurian; of the upper silurian; of the devonian; of the carboniferous; of the permian; of the trias; of the jurassic; of the cretaceous; of the eocene. _brachymetopus_. brachyurous crustaceans. bradford clay. breaks in the geological and palæontological record. breccia. brick-earths. bridlington crag. brittle-stars (_see_ ophiuroidea). _bronteus_. _brontotheridoe_. _brontotherium ingens_. _brontozoum_. _buccinum_. _bucklandia_. _bulimus_. bunter sandstein. butterflies. _byssoarca_. cainozoic (_see_ kainozoic). calamaries. _calamites; cannoeformis_. calcaire grossier. calcareous rocks; tufa. calciferous sand-rock. _calveria_. _calymene; blumenbachii_. _camarophoria globulina_. cambrian period; rocks of, in britain; in bohemia; in north america; life of. _camelopardalidoe_. camels. _canis lupus; parisiensis_. caradoc rocks. carbon, origin of. carboniferous limestone. carboniferous period; rocks of; life of. carboniferous slates of ireland. _carcharias_. _carcharodon; productus_. _cardinia_. _cardiocarpon_. _cardiola; fibrosa; interrupta_. _cardita; planicosta_. _cardium; rhoeticum_. caribou. _carnivora_, of the eocene; of the miocene; of the pliocene; of the post-pliocene. _caryocaris_. _caryocrinus ornatus_. _castor fiber_. _castoroides ohioensis_. catastrophism, theory of. _catopterus_. cauda-galli grit. _caulopteris_. cave-bear. cave-deposits. cave-hyæna. cave-lion. caves, formation of; deposits in. _cavicornia_. cement-stones. _cephalaspis_. _cephalopoda_, of the cambrian period; of the lower silurian; of the upper silurian; of the devonian; of the carboniferous; of the permian; of the trias; of the jurassic; of the cretaceous; of the eocene; of the miocene. _ceratiocaris_. _ceratites; nodosus_. _ceratodus; altus; fosteri; serratus_. _ceriopora; hamiltonensis_. _cerithium; _hexagonum_. _cervidoe_, of the miocene period; of the pliocene; of the post-pliocene. _cervus; capreolus; elaphus; megaceros; tarandus_. _cestracion philippi_. cestracionts, of the devonian; of the carboniferous; of the permian; of the trias; of the jurassic; of the cretaceous. _cetacea_; of the eocene; of the miocene. _cetiosaurus_. _choeropotamus_. _choetetes; tumidus_. chain-coral. chalk; structure of; foraminifera of; origin of; with flints; without flints. _chama_. _chamoerops; helvetica_. chazy limestone. _cheiroptera_, of the eocene; of the miocene. _cheirotherium_. _cheirurus; bimucronatus_. _chelichnus duncani_. _chelone benstedi; planiceps_. _chelonia_, of the permian; of the jurassic; of the cretaceous; of the eocene; of the miocene. _chemnitzia_. chemung group. chert. chillesford beds. _chonetes; hardrensis_. _chonophyllum_. _cidaris_. cincinnati group. _cinnamomum polymorphum_. cinnamon-trees. _cladodus_. claiborne beds. _clathropora; intertexta_. clay; red, origin of. clay-ironstone, nodules of. _cleidophorus_. _cleodora_. _climacograptus_. clinton formation. _clisiophyllum_. _clupeidoe_. _clymenia; sedgwickii_. coal; structure of; mode of formation of. coal-measures; mineral characters of; mode of formation of; plants of. coccoliths. _coccosteus_. _cochliodus; cantortus_. _coleoptera_. _colossochelys atlas_. _columnaria; alveolata_. _comatula_. conclusions to be drawn from fossils. concretions, calcareous; phosphatic; of clay-ironstone; of manganese. conglomerate. _coniferoe_; wood of; of devonian period; of the carboniferous; of the permian; of the trias; of the jurassic period. coniston flags and grits. connecticut sandstones, footprints of. _conocoryphe mathewi; sultzeri_. conodonts. _constellaria_. constricting serpents of the eocene. contemporaneity of strata. continuity, theory of. _conularia; ornata_. _conulus_. _conus_. coomhola grits. coprolites. coralline crag. corallines. _corallium_. coral-rag. coral-reefs. coral-rock. coral-sand. corals; of the lower silurian; of the upper silurian; of the devonian; of the carboniferous; of the permian; of the trias; of the jurassic; of the cretaceous; of the eocene; of the miocene. _corbula_. cornbrash. corniferous limestone. _cornulites_. cornus. _coryphodon_. cowries. crabs. crag, red; white; norwich; antwerp; bridlington; coralline. _crania; ignabergensis_. _crassatella_. _crepidophyllum; archiaci_. cretaceous period; rocks of, in britain; in north america; life of. crinoidal limestone. _crinoidea_; of the cambrian; of the lower silurian; of the upper silurian; of the devonian; of the carboniferous; of the permian; of the triss; of the jurassic; of the cretaceous; of the eocene. _crioceras; cristatum_. _crocodilia_; of the trias; of the jurassic; of the cretaceous; of the eocene. cromer forest-bed. _crossozamites_. _crotalocrinus_. _crustacea_, of the cambrian; of the lower silurian; of the upper silurian; of the devonian; of the carboniferous; of the permian; of the trias; of the jurassic; of the cretaceous. cryptogams. _ctenacanthus_. _ctenodonta_. _cupressus_. cursores. cuttle-fishes (_see_ dibranchiate cephalopods). _cyathocrinus_. _cyathophyllum_. _cycadopteris_. cycads; of the carboniferous; of the permian; of the trias; of the jurassic; of the cretaceous. _cyclas_. _cyclonema_. _cyclophthalmus senior_. _cyclostoma; arnoudii_. _cynodraco_. _cyproea; elegans_. cypress. _cypridina_. cypridina slates. _cyrena_. _cyrtina_. _cyrtoceras_. _cystiphyllum; vesiculosum_. _cystoidea_; of the cambrian; of the lower silurian; of the upper silurian. dachstein beds. _dadoxylon_. _daonella; lommelli_. _dasornis londinensis_. decapod crustaceans. deer. _deinosauria_; of the trias; of the jurassic; of the cretaceous. _deinotherium; giganteum_. denbighshire flags and grits. _dendrocrinus_. _dendrograptus_. desmids. devonian formation; origin of name; relation to old red sandstone; of devonshire; of north america; life of. _diadema_. diatoms; of the devonian; of the carboniferous; of flints; of richmond earth. dibranchiate cephalopods; of the trias; of the jurassic; of the cretaceous; of the eocene; of the miocene. _diceras; arietina_. diceras limestone. _dichobune_. _dichograptus; octobrachiatus_. dicotyledonous plants. _dicotyles antiquus_. _dicranograptus_. _dictyonema; sociale_. _dicynodon; lacerticeps_. _didelphys; gypsorum_. _didus ineptus_. _didymograptus; divaricatus_. _dikellocephalus celticus; minnesotensis_. _dimorphodon_. _dinichthys; hertzeri_. _ditoceras; mirabilis_. _dinocerata_. _dinophis_. _dinornis; elephantopus; giganteus_. _dinosauria_ (see _deinosauria_). _dinotherium_ (see _deinotherium_). _diphyphyllum_. _diplograptus; pristis_. _dipnoi_. _diprotodon; australis_. _diptera_. _discina_. _discoidea; cylindrica_. _dithyrocaris; scouleri_. dodo. dog whelks. dolomite. dolomitic couglomerate of bristol. dolphins. _dorcatherium_. downton sandstone. _draco volans_. dragon-flies. drift, glacial. _dremotherium_. _dromatherium sylvestre_. _dryandra_. _dryopithecus_. dugougs. _echinodermata_, of the cambrian; of the lower silurian; of the upper silurian; of the devonian; of the carboniferous; of the permian; of the trias; of the jurassic; of the cretaceous; of the eocene. _echinoidea_; of the upper silurian; or the devonian; of the carboniferous; of the permian; of the jurassic; of the cretaceous. _edentata_; of the eocene; of the miocene; of the post-pliocene. _edriocrinus_. eifel limostone. _elasmobranchii_ (_see_ placoid fishes). _elasmosaurus_. elephants. _elphas; americanus; antiquus; falconeri; melitensis; meridionalis; planifrons; primigenius_. elk; irish. _ellipsocephalus hoffi_. _elotherium_. _emydidoe_. _emys_. enaliosaurians. encrinital warble. _encrinurus_. _encrinus liliiformis_. endogenous plants. _endophyllum_. _endothyra; bailyi_. engis skull. _entomis_. _entomoconchus scouleri_. eocene period; rocks of, in britain; in france; in north america; life of. _eocidaris_. _eophyton; linneanum_. eophyton sandstone. _eosaurus acadianus_. eozoic rocks. _eozoön bavaricum_. _eozoön canadense_; appearance of, in mass; minute structure of; affinities of, with _foraminifera_. _ephemeridoe_. _equisetaceoe_. _equisetites_. _equidoe_. _equus; caballus; excelsus; fossilis_. _eridophyllum_. _eryon arctiformis_. _eschara_. _escharidoe_. _escharina; oceani_. _estheria; tenella_. _eucalyptocrinus; polydactylus_. _eucladia_. _euomphalus; discors_. _euplectella_. _euproöps_. european bison. _eurypterida_; of the upper silurian; of the devonian. even-toed ungulates. exogenous plants. _exogyra; virgula_. extinction of species. _fagus_. faluns. fan-palms. _favistella_. _favostites; gothlandica; hemisphoerica_. faxöe limestone. _felis angustus; leo; speloea_. _fenestella; cribrosa; magnifica; retiformis_. _fenestellidoe_. ferns, of the devonian; of the carboniferous; of the permian; of the trias; of the jurassic; of the cretaceous. fig-shells. fishes; of the upper silurian; of the devonian; of the carboniferous; of the permian; of the trias; of the jurassic; of the cretaceous; of the eocene; of the miocene. flint; structure of; origin of; organisms of; of chalk. human implements associated with bones of extinct mammals. flora (_see_ plants). footprints of _cheirotherium_; of the triassic sandstones of connecticut. _foraminifera_; of the cambrian; of the lower silurian; of the carboniferous; of the permian; of the trias; of the jurassic; of the cretaceous; of the eocene; of the miocene; of the post-pliocene; of atlantic ooze; as builders of limestone; as forming green sands. _forbesiocrinus_. forest-bed of cromer. forest-bugs. forest-marble. formation, definition of; succession of. fossiliferous rocks; chronological succession of. fossilisation, processes of. fossils, definition of; distinctive, of rock-groups; conclusions to be drawn from; biological relations of. foxes. fringe-finned ganoids. fucoidal sandstone. fucoids. fuller's earth. _fusulina; cylindrica_. _fusus_. _galeocerdo_. _galerites; albo-galerus_. _galestes_. ganoid fishes; of the upper silurian; of the devonian; of the carboniferous; of the permian; of the trias; of the jurassic; of the cretaceous; of the eocene. gaspé beds. _gasteropoda_, of the cambrian; of the lower silurian; of the upper silurian; of the devonian; of the carboniferous; of the permian; of the trias; of the jurassic; of the cretaceous; of the eocene. _gastornis parisiensis_. gault. gavial. genesee slates. geological record, breaks in the. giraffes. glacial period; deposits of. _glandulina_. glauconite. _glauconome; pulcherrima_. globe crinoids (_see_ cystoidea). _globigerina_. glutton. _glyptaster_. _glyptocrinus_. _glyptodon; clavipes_. _glyptoloemus_. goats. _goniatites; jossoe_. _gorgonidoe_. _grallatores_. graphite; mode of occurrence of; origin of. _graptolites_; structure of; of the lower silurian; of the upper silurian. great oolite; upper. greenland. miocene plants of. greensand, lower. green sands, origin of. _grevillea_. _griffithides_. grizzly bear. groond sloths. _gryphoea; incurva_. guelph limestone. _gulo luscus; speloeus_. guttenstein beds. gymnospermous exogens. gypsum. _gyracanthus_. _gyroceras_. _hadrosaurus_. _halitherium_. hallstadt beds. _halobia_. _halysites; agglomerata; catenularia_. hamilton formation. _hamites; rotundus_. _haplophlebium barnesi_. harlech grits. _harpes; ungula_. hastings sands. headon and osborne series. heart-urchins. _heliolites_. _heliophyllum; exiguum_. _helix_. _helladotherium_. _helopora fragilis_. _hemicidaris crenularis_. _hemiptera_. _hemitrochiscus paradoxus_. hempstead beds. _hesperornis; regalis_. _heteropoda_; of the lower silurian; of the upper silurian; of the devonian; of the carboniferous. _hinnites_. _hipparion_. _hippopodium_. _hippopotamus; amphibus; major; sivalensis_. _hippothoa_. hippurite marble. _hippurites; toucasiana_. _hippuritidoe_. _histioderma_. hollow-horned ruminants. _holocystis elegan_. _holopea; subconica_. _holopella; obsoleta_. _holoptychius; nobilissimus_. holostomatous univalves. holothurians. _holtenia_. _homacanthus_. _homalonotus; armatus_. _homo diluvii testis_. honeycomb corals. hoofed quadrupeds. hudson river group. huronian period; rocks of. _hyoena crocuta; speloea; hipparionum_. _hyoenictis_. _hyoenodon_. _hyalea d'orbignyana_. _hybodus_. _hydractinia_. hydroid zoophytes. _hymenocaris vermicauda_. _hymenophyllites_. _hymenoptera_. _hyopotamus_. _hyperodapedon_. _hypsiprymnopsis_. _hystrix primigenius_. _ichthyocrinus loevis_. _ichthyornis; dispar_. _ichthyosaurus; communis_. _ictitherium_. _iguana_. _iguanodon; mantelli_. ilfracombe group. _illoenus_. imperfection of the palæontological record. inferior oolite. infusorial earth. _inoceramus; sulcatus_. _insectivora_, of the eocene; of the miocene. insects, of the devonian; of the carboniferous; of the jurassic; of the miocene. irish elk. _ischadites_. isopod crustaceans. jackson beds. jurassic period; rocks of; life of. _kaidacarpum_. kainozoic period. kangaroo. kelloway rock. kent's cavern, deposits in. keuper. kimmeridge clay. king-crabs. _koninckia_. kössen beds. _labyrinthodon joegeri_. _labyrinthodontia_; of the carboniferous; of the permian; of the trias. lace-corals. _lacertilia_; of the permian; of the trias; of the jurassic; of the cretaceous. _loelaps_. _lamellibranchiata_, of the cambrian; of the lower silurian; of the upper silurian; of the devonian; of the carboniferous; of the permian; of the trias; of the jurassic; of the cretaceous; of the eocene. _lamna_. lamp-shells (see _brachiopoda_). land-tortoises. _lauraceoe_. laurentian period; rocks of; lower laurentian; upper laurentian; areas occupied by laurentian rocks; limestones of; iron-ores of; phosphate of lime of; graphite of; life of. leaf-beds of the isle of mull. _leda; truncata_. _leguminosites marcouanus_. lemming. _lepadidoe_. _lepadocrinus gebhardi_. _leperditia; canadensis_. _lepidaster_. _lepidechinus_. _lepidesthes_. lepidodendroids. _lepidodendron; sternberg_. _lepidoptera_. _lepidosiren_. _lepidosteus_. _lepidostrobus_. _lepidotus_. _leptoena; liassica; sericea_. _leptocoelia; plano-convexa_. lias. lichas. _licrophycus ottawaensis_. lignitic formation of north america. lily-encrinite. _lima_. lime, phosphate of. limestone; varieties of; origin of; microscopical structure of; crinoidal; foraminiferal; coralline; magnesian; metamorphic; oolitic; pisolitic; bituminous; laurentian. _limnoea; pyramidalis_. _limulus_. _lingula; credneri_. lingula flags. _lingulella; davisii; ferruginea_. _liriodendron; meeki_. _lithostrotion; irregulare_. _lituites_. lizards (see _lacertilia_). llama. llanberis slates. llandeilo rocks. llandovery rocks; lower; upper. lobsters. loess. london clay. longmynd rocks. _lonsdaleia_. _lophiodon_. _lophophyllum_. lower cambrian; chalk; cretaceous; devonian; eocene; greensand; helderberg; laurentian rocks; ludlow rock; miocene; old red sandstone; oolites; silurian period; rocks of, in britain; in north america; life of. _loxonema_. ludlow rock. _lycopodiaceoe_. lynton group. _lyrodesma_. macaques. _machoeracanthus major_. _machairodus; cultridens_. _maclurea; crenulata_. _macrocheilus_. _macropetalichthys; sullivanti_. _macrotherium giganteum_. _macrurous crustaceans_. _mactra_. maestricht chalk. magnesian limestone; nature and structure of; of the permian series. magnolia. _mammalia_, of the trias; of the jurassic; of the eocene; of the miocene; of the pliocene; of the post-pliocene. mammoth. man, remains of, in post-pliocene deposits. manatee. _mantellia; megalophylla_. maple. marble; encrinital; statuary. marcellus shales. _mariacrinus_. marmots. marsupials; of the trias; of the jurassic; of the eocene; of the miocene; of the post-pliocene. _marsupiocrinus_. _marsupites_. _mastodon; americanus, angustidens; arvenensis; longirostris; ohioticus; sivalensis_. medina sandstone. _megalichthys_. _megalodon_. _megalomus_. _megalonyx_. _megalosaurus_. _megatherium; cuvieri_. _melania_. _melonites_. menevian group. _menobranchus_. _meristella; cylindrica; intermedia; naviformis_. _mesopithecus_. mesozoic period. _michelinia_. _micraster_. _microlestes; antiquus_. middle devonian; eocene; oolites; silurian. miliolite limestone. _millepora_. millstone grit. miocene period; rocks of, in britain; in france; in belgium; in switzerland; in austria; in germany; in italy; in india; in north america; life of. mitre-shells. _mitra_. moas of new zealand. _modiolopsis; solvensis_. molasse. mole. monkeys. monocotyledonous plant. _monograptus; priodon_. _monotis_. monte bolca, fishes of. _montlivaltia_. mosasauroids. _mosasaurus; camperi; princeps_. mountain limestone. mud-fishes. mud-turtles. mull, miocene strata of. _murchisonia; gracilis_. _murex. muschelkalk. musk-deer. musk-ox. musk-sheep. _myliobatis edwardsii_. _mylodon; robustus_. _myophoria; lineata_. _myriapoda_ of the coal. _nassa_. _natatores_. _natica_. _nautilus; danicus; pompilius_. neanderthal skull. neocomian series. _neolimulus_. _nerinoea; goodhallii_. _nerita_. _neuroptera_. _neuropteris_. newer pliocene. new red sandstone. newts. niagara limestone. _nipadites; ellipticus_. _noeggerathia_. norwich crag. _nothosaurus; mirabilis_. _notidanus_. _numenius gypsorum_. _nummulina; loevigata; pristina_. _nummulitic limestone_. oak. _obolella; sagittalis_. odd-toed ungulates. _odontaspis_. _odontopteris; schlotheimi_. _odontopteryx; toliapicus_. _odontornithes_. _ogygia; buchii_. older pliocene. _oldhamia; antiqua_; slates of ireland. old red sandstone; origin of name; of scotland; relations of, to devonian. _olenus; micrurus_. oligocene. _oligoporus_. olive-shells. _omphyma_. _onchus; tenuistriatus_. oneida conglomerate. _onychodus; sigmoides_. oolitic limestone, structure of; mode of formation of. oolitic rocks (_see_ jurassic). ooze, atlantic. _ophidia_; of the eocene. _ophiuroidea_, of the lower silurian; of the upper silurian; of the carboniferous; of the trias; of the jurassic. opossum. _orbitoides_. oriskany sandstone. _ormoxylon_. _orohippus_. _orthis; biforata; davidsoni; elegantula; flabellulum; hicksii; lenticularis; plicatella; resupinata; subquadrala; testudinaria_. _orthoceras; crebriseptum_. _orthonota_. _orthoptera_. _osmeroides; mantelli_. _osmerus_. _ostealepis_. _ostracode_ crustaceans of the cambrian; of the lower silurian; of the upper silurian; of the devonian; of the carboniferous; of the permian; of the trias; of the jurassic; of the cretaceous. _ostrea acuminata; couloni; deltoidea; distorta; expansa, gregarea; marshii_. _otodus; obtiquus_. _otozamites_. _otozoum_. _oudenodon; bainii_. _ovibos moschatus_. oxford clay. _oxyrhina; xiphodon_. oysters. _pachyphyllum_. _paloearca_. _paloeaster; ruthveni_. _palasterina; primoeva_. _paloechinus; ellipticus_. _paloeocaris; typus_. _paloeocoma; colvini_. _paloeocoryne_. palæolithic man, remains of. _paloeomanon_. _paloeoniscus_. _paloeontina oolitica_. palæontological evidence as to evolution. palæontological record, imperfection of the. palæontology, definition of. _paloeonyctis_. _paloeophis; toliapictus; typhoeus_. _paloeoreas_. _paloeosaurus; platyodon_. _paloeosiren beinerti_. _paloeotherium; magnum_. _paloeoxylon_. palæozoic period. palms. _paludina_. _pandaneoe_. _pandanus_. _paradoxides; bohemicus_. _parasmilia_. _parkeria_. pear encrinite. pearly nautilus. peccaries. _pecopteris_. _pecten groenlandicus; islandicus; valoniensis_. penarth beds. _pennatulidoe_. _pentacrinus; caput-medusoe; fasciculosus_. _pentamerus; galeatus; knightii_. _pentremites_ (_see_ blastoidea). _pentremites conoideus; pyriformis_. perching birds. _percidoe_. _periechocrinus_. _perissodactyle ungulates_. permian period; rocks of, in britain; in north america; life of. persistent types of life. _petalodus_. _petraster_. petroleum, origin of. pezophaps. _phacops; downingioe; granulatus; loevis; latifrons; longicaudatus; rana_. _phoenopora ensiformis_. phalangers. phanerogams. _phaneropleuron_. _phascolotherium_. _pheronema_. _phillipsastroea_. _phillipsia; seminifera_. _pholadomya_. _phormosoma_. _phorus_. phosphate of lime, concretions of; disseminated in rocks; origin of. _phyllograptus; typus_. _phyllopoda_, of the cambrian; of the lower silurian; of the upper silurian; of the devonian; of the carboniferous; of the permian; of the trias. _phyllopora_. _physa; columnaris_. pigs. pilton group. _pinites_. _pisces (_see_ fishes). _pisolite_. pisolitic limestone of france. _placodus; gigas_. placoid fishes; of the upper silurian; of the devonian; of the carboniferous; of the permian; of the trias; of the jurassic; of the cretaceous; of the eocene; of the miocene. _plagiaulax_. _planolites; vulgaris_. _planorbis_. plants, of the cambrian; of the lower silurian; of the upper silurian; of the devonian; of the carboniferous; of the permian; of the trias; of the jurassic; of the cretaceous; of the eocene; of the miocene. _plasmopora_. _platanus; aceroides_. _platephemera antiqua_. _platyceras; dumosum; multisinuatum; ventricosum_. _platycrinus; tricontadactylus_. _platyostoma; niagarense_. platyrhine monkeys. _platyschisma helicites_. _platysomus; gibbosus_. _platystoma_. pleistocene period; climate of. _plesiosaurus; dolichodeirus_. _pleurocystites squamosus_. _pleurotoma_. _pleurotomaria_. _plicatula_. pliocene period; rocks of, in britain; in belgium; in italy; in north america; life of. _pliopithecus; antiquus_. _pliosaurus_. _podocarya_. _podozamites; lanceolatus_. polir-schiefer. _polycystina_; of barbadoes-earth. _polypora; dendroides_. _polypterus_. _polystomella_. _polytremacis_. _polyzoa_, of the cambrian; of the lower silurian; of the upper silurian; of the devonian; of the carboniferous; of the permian; of the trias; of the cretaceous; of the miocene. _populus_. _porcellia_. porcupines. portage group. port-jackson shark. portland beds. post-glacial deposits. post-pliocene period. post-tertiary period. _poteriocrinus_. potsdam sandstone. pre-glacial deposits. _prestwichia; rotundata_. _primitia; strangulata_. primordial trilobites. primordial zone. _proboscidea_, of the miocene; of the pliocene; of the post-pliocene. _producta; horrida; longispina; semireticulata_. _productella_. _productidoe_. _proëtus_. prong-buck. _protaster; sedgwickii_. _proteaceoe_. _proteus_. _protichnites_. _protocystites_. _protornis glarisiensis_. _protorosaurus; speneri_. _protospongia; fenestrata_. _prototaxites; logani_. _psammobia_. _psammodus_. _psaronius_. _pseudocrinus bifasciatus_. _psilophyton; princeps_. _pteranodon; longiceps_. _pteraspis; banksii_. _pterichthys; cornutus_. _pterinoea; subfalcata_. _pteroceras_. _pterodactylus; crassirostris_. _pterophyllum; joegeri_. _pteropoda_, of the cambrian; of the lower silurian; of the upper silurian; of the devonian; of the carboniferous; of the permian; of the jurassic. _pterosauria_; of the jurassic; of the cretaceous. _pterygotus anglicus_. _ptilodictya; acuta; falciformis; raripora; schafferi_. _ptychoceras; emericianum_. _ptychodus_. _pupa vetusta_. purbeck beds; mammals of. _puryuroidea_. _pycnodus_. _pyrula_. _quadrumana_, of the eocene; of the miocene; of the pliocene; of the post-pliocene. quadrupeds (_see_ mammalia). quaternary period. quebec group. _quercus_. rabbits. _rana_. _raptores_. _rasores_. recent period. _reptaculites_. red clays, origin of. red coral. red crag. red deer. reindeer. _remopleurides_. reptiles; of the permian; of the trias; of the jurassic; of the cretaceous; of the eocene. _retepora; ehrenbergi; phillipsi_. _retiolites_. _retzia_. _rhætic beds_. _rhamphorhynchus; bucklandi_. _rhinoceridoe_. _rhinoceros etruscus; leptorhinus; megarhinus; tichorhinus_. _rhinopora verrucosa_. _rhizodus_. _rhombus minimus_. rhyncholites. _rhynchonella; cuneata; neglecta; pleurodon; varians. _rhynchosaurus; articeps. rice-shells. richmond earth. ringed worms (_see_ annelida). river-gravels, high-level and low-level. _robulina_. rocks, definition of; divisions of; igneous; aqueous; mechanically-formed; chemically-formed; organically-formed; arenaceous; argillaceous; calcareous; siliceous. _rodentia_, of the eocene; of the miocene; of the post-pliocene. roebuck. _rostellaria_. _rotalia; boueana_. rugose corals; of the lower silurian; of the upper silurian; of the devonian; of the carboniferous; of the permian; of the upper greensand. rupelian clay. _sabal major_. sabre-toothed tiger. _saccammina_. _saccosoma. salamanders. salina group. _salix; meeki_. _salmonidoe_. _sao hirsuta_. _sassafras cretacea_. _sauropterygia_. _scalaria; groenlandica_. _scaphites; oequalis_. _schizodus_. schoharie grit. _scolecoderma_. _scoliostoma_. _scolithus; canadensis_. scorpions of the coal-measures. scorpion-shells. screw-pines. _scutella; subrotunda_. sea-cows (_see_ sirenia). sea-lilies (_see_ crinoidea). sea-lizards (_see_ enaliosaurians). seals. sea-mats and sea-mosses (_see_ polyzoa). sea-shrubs (_see_ gorgonidæ). sea-urchins (_see_ echinoidea). sea-weeds. secondary period. sedimentary rocks. _semnopithecus_. septaria. _sequoia; couttsioe; gigantea; langsdorffii_. _serolis_. serpents (_see_ ophidia). _serpulites_. sewâlik hills (_see_ siwâlik hills). sheep. shell-sands. _sigillaria; groeseri_. sigillarioids. silicates, infiltration of the shells of foraminifera by. siliceous rocks. siliceous sponges. silicification. silurian period (_see_ lower silurian and upper silurian). _simosaurus; gaillardoti_. _siphonia; ficus_. siphonostomatous univalves. _siphonotreta_. _sirenia_; of the eocene; of the miocene. _siren lacertina_. _sivatherium; giganteum_. siwâlik hills, miocene strata of. skiddaw slates. sloths. _smilax_. _smithia_. snakes (_see_ ophidia). soft tortoises. _solarium_. solenhofen slates. solitaire. _spalacotherium_. _spatangus_. _sphoerospongia_. _sphagodus_. _sphenodon_. _sphenopteris_. spiders of the coal-measures. spider-shells. spindle-shells. _spirifera; crispa; disjuncta; hysterica; mucronata; niagarensis; rostrata; sculptilis; trigonalis_. _spiriferidoe_. _spirophyton cauda-galli_. _spirorbis; arkonensis; carbonarus; laxus; lewisii; omphalodes; spinulifera_. _spirulirostra_. _spondylus; spinosus_. sponges, of the cambrian; of the lower silurian; of the upper silurian; of the devonian; of the carboniferous; of the permian; of the trias; of the jurassic; of the cretaceous. _spongilla_. _spongillopsis_. _spongophyllum_. spore-eases, of cryptogams in the ludlow rocks; in the coal. squirrels. _stagonolepis_. staircase-shell. stalactite. stalagmite. star-corals. star-fishes. st cassian beds. _stephanophyllia_. _stereognathus_. _stigmaria; ficoides_. stonesfield slate; mammals of. strata, contemporaneity of. stratified rock. _streptelasma_. _streptorhynchus_. _stromatopora; rugosa; tuberculata_. _strombodes; pentagonus_. _strombus_. _strophalosia_. _strophodus_. _strophomena; alternata; deltoidea; filitexta; rhomboidalis; subplana_. sub-apennine beds. sub-carboniferous rocks. succession of life upon the globe. _suida_. sulphate of lime. _sus erymanthius; scrofa_. _synastroea_. _synhelia sharpeana_. _synocladia; virgulacea_. _syringopora; ramulosa_. tabulate corals; of the lower silurian; of the upper silurian; of the devonian; of the carboniferous; of the permian. _talpa europoea_. _tapiridoe_. tapirs. _tapirus arvernensis_. _taxocrinus tuberculatus_. _taxodium_. _teleosaurus_. teleostean fishes; of the cretaceous. _telerpeton elginense_. _tellina proxima_. _tentaculites; ornatus_. _terebra_. _terebratella; astleriana_. _terebratula; digona; elongata; hastata; quadrifida; sphoeroidalis_. _terebratulina; caput-serpentis; striata_. termites. terrapins. tertiary period. tertiary rocks, classification of. _testudinidoe_. tetrabranchiate cephalopods; of the cambrian; of the lower silurian; of the upper silurian; of the devonian; of the carboniferous; of the permian; of the trias; of the jurassic; of the cretaceous; of the eocene; of the miocene. _textularia; meyeriana_. thanet sands. _theca_. _theca davidii_. _thecidium_. thecodont reptiles. _thecodontosaurus; antiquus_. _thecosmilia annularis_. _thelodus_. theriodont reptiles. _thylacoleo_. tile-stones. _titanotherium_. toothed birds. tortoises. _tragoceras_. travertine. tree-ferns, of the devonian; of the coal-measures. tremadoc slates. _trematis_. trenton limestone. _trianthrus beckii_. triassic period; rocks of, in britain; in germany; in the austrian alps; in north america; life of. _triconodon_. _trigonia_. _trigoniadoe_. _trigonocarpum; ovatum_. trilobites; of the cambrian; of the lower silurian; of the upper silurian; of the devonian; of the carboniferous. _trimerellidoe_. _trinucleus; concentricus_. _trionycidoe_. _triton_. _trochocyathus_. _trochonema_. _trogontherium; cuvieri_. trumpet-shells. tulip-tree. _turbinolia sulcata_. _turbinolidoe_. _turrilites; catenulatus_. _turritella_. turtles. _typhis tubifer_. _ullmania selaginoides_. unconformability of strata. under-clay of coal. _ungulata_, of the eocene; of the miocene; of the pliocene; of the post-pliocene. uniformity, doctrine of. _unio_. univalves (_see_ gasteropoda). upper cambrian; chalk; cretaceous; devonian; eocene; greensand; helderberg; laurentian; llandovery; ludlow rock; miocene; oolites; silurian period; rocks of, in britain; in north america; life of. _ursus arctos; arvernensis; ferox; speloea_. _ursus_. valley-gravels, high-level and low-level. _vanessa pluto_. _varanidoe_. vegetation (_see_ plants). _ventriculites; simplex_. venus's flower-basket. _vermilia_. _vespertilio parisiensis_. vicksburg beds. vines. vitreous sponges. _voltzia; heterophylla_. _voluta; elongata_. volutes. _walchia; piniformis_. walrus. wealden beds. _wellingtonia_. wenlock beds; limestone; shale. wentle-traps. werfen beds. whalebone whales. whales. whelks. white chalk; structure of; origin of. white crag. white river beds. wild boar. _williamsonia_. winged lizards (_see_ pterosauria). winged snails (_see_ pteropods). wing-shells. wolf. wolverine. wombats. woolhope limestone. woolly rhinoceros. woolwich and reading beds. worm-burrows. _xanthidia_. _xenoneura antiquorum_. _xiphodon_. _xylobius; sigillarioe_. _zamia spiralis_. _zamites_. _zaphrentis; cornicula; stokesi; vermicularis_. _zeacrinus_. zechstein. _zeuglodon; cetoides_. theory of the earth with proofs and illustrations. in four parts. _by james hutton, m.d. and f.r.s.e._ vol. ii. contents. part ii. _farther induction of facts and observations, respecting the geological part of the theory_ _introduction_ chap. i. _facts in confirmation of the theory of elevating land above the surface of the sea._ chap. ii. _the same subject continued, with examples from different countries._ chap. iii. _facts in confirmation of the theory, respecting those operations which re-dissolve the surface of the earth._ chap. iv. _the same subject continued, in giving still farther views of the dissolution of the earth._ chap. v. _facts in confirmation of the theory respecting the operations of the earth employed in forming soil for plants._ chap. vi. _a view of the economy of nature, and necessity of wasting the surface of the earth, in serving the purposes of this world._ chap. vii. _the same subject continued, in giving a view of the operations of air and water upon the surface of the land._ chap. viii. _the present form of the surface of the earth explained, with a view of the operation of time upon our land._ chap. ix. _the theory illustrated, with a view of the summits of the alps._ chap. x. _the theory illustrated, with a view of the valleys of the alps._ chap. xi. _facts and opinions concerning the natural construction of mountains and valleys._ chap. xii. _the theory illustrated, by adducing examples from the different quarters of the globe._ chap. xiii. _the same subject continued._ chap. xiv. _summary of the doctrine which has been now illustrated._ part ii. _farther induction of facts_ and _observations, respecting the geological part_ of the _theory_. introduction. by the present theory, the earth on which we dwell is represented as having been formed originally in horizontal strata at the bottom of the ocean; hence it should appear, that the land, in having been raised from the sea, and thus placed upon a higher level, had been of a different shape and condition from that in which we find it at the present time. this is a proposition now to be considered. in whatever order and disposition the hard and solid parts of the land were at the time of its emerging from the surface of the sea, no provision would have then been made for conducting the rivers of the earth; therefore, the water from the heavens, moving from the summits of the land to the shores, must have formed for themselves those beds or channels in which the rivers run at present; beds which have successively changed their places over immense extents of plains that have often been both destroyed and formed again; and beds which run between the skirts of hills that have correspondent angles, for no other reason but because the river has hollowed out its way between them. in this view of things, the form of our land must be considered as having been determined by three different causes, all of which have operated, more or less, in producing the present state of those things which we examine. first, there is a regular stratification of the materials, from whence we know the original structure, shape, and situation of the subject. secondly, there are the operations of the mineral region, some of which have had regular effects upon the strata, as we find in the veins or contractions of the consolidated masses; others have had more irregular effects, but which may still be distinguished by means of our knowing the original state and structure of those masses. lastly, there are operations proper to the _surface_ of this globe, by which the form of the habitable earth may be affected; operations of which we understand both the causes and the effects, and, therefore, of which we may form principles for judging of the past, as well as of the future. such are the operations of the fun and atmosphere, of the wind and water, of the rivers and the tides. it is the joint operation and result of those three different causes that are to be perceived in the general appearances of this earth, and not the effects of any one alone; although, in particular places of the earth, the operation peculiar to each of these may be considered by itself, in abstracting those of the others, more or less. thus there are several views in which the subject is to be examined, in order to find facts with which the result of the theory may be compared, and by which confirmation may be procured to our reasoning, as well as explanation of the phenomena in question. chapter i. _facts in confirmation of the theory of elevating land above the surface of the sea._ the first object now to be examined, in confirmation of the theory, is that change of posture and of shape which is so frequently found in mountainous countries, among the strata which had been originally almost plain and horizontal. here it is also that an opportunity is presented of having sections of those objects, by which the internal construction of the earth is to be known. it is our business to lay before the reader examples of this kind, examples which are clearly described, and which may be examined at pleasure. no person has had better opportunities of examining the structure of mountains than m. de saussure, and no body more capable of taking those comprehensive views that are so necessary for the proper execution of such a task. we shall therefore give some examples from this author, who has every where described nature with a fidelity which even inconsistency with his system could not warp. speaking of the general situation of the beds of the saleve, (p. .) «dans quelques endroits, et même presque partout, les couches descendent tout droit du haut de la montagne jusques à son pied: mais au dessus de collonge le sommet arrondi en dos d'âne présente des couches qui descendent de part et d'autre, au sud-est vers les alpes, et au nord-ouest vers notre vallée; avec cette difference, que celles qui descendent vers les alpes parviennent jusques au bas; au lieu que celles qui nous regardent sont coupées à pic, à une grande hauteur. «ces deux inclinaisons ne sont pas les seules que l'on observe dans le bancs du mont saleve, ils en ont encore une troisième; ils sont relevés vers le milieu de la longueur de la montagne, et descendent de là vers ses extrémités. cette pente, qui sur le grand saleve n'est pas bien sensible, devient très remarquable au petit saleve, et même très rapide à son extrémité. les dernières couches au nord au dessus d'Étrembières descendent vers le nord-nord-est, sous un angle de au degrés. «on verra, dans le cours de cet ouvrage, combien le montagnes calcaires ont fréquemment cette forme. «§ . outre ces grandes couches qui constituent le corps de la montagne, et qui peuvent en général être mises dans la classe des couches horizontales, on en trouve d'autres dont l'inclinaison est absolument différente. elles sont situés au bas de grande saleve du coté qui regarde notre vallée; on les voit appliquées contre les tranches inférieures des bancs horizontaux ou très-inclinées en appui contre la montagne. «ces couches s'élèvent en quelques endroits, par exemple, entre veiry et crévin, à peu-près à la moitié de la hauteur du grande saleve. celles qui touchent immédiatement la montagne, sont le plus inclinées; on en voit là de verticales et même quelque fois de renversées en sens contraire, qui sont soutenues par le plus extérieures. celle ci font avec l'horizon un angle de à degrés. ces couches sont souvent très étendues, bien suivies, et continues à de très-grandes distances. leur assemblage forme une épaisseur considérable au pied de la montagne. elles ont cependant été rompues, et manquent même totalement dans quelques places. cela même donne la facilité de les bien observer, parce qu'en se postant dans ces intervalles, on peut les prendre en flanc, et voir distinctement leurs tranches, et tout leur structure. «on observe ces couches non-seulement au pied de rocs nuds du grand saleve, mais encore dans la partie de sa pente qui est boisée par exemple au dessous de la croisette, le chemin qui de ce hameau descend au village de collonge, passe sur les couches inclinées, comme celles que je viens de décrire.» in § , the description is continued. «en suivant le pied de la montagne entre le coin et crévin, on voit reparaître nos couches verticales ou très inclinées qui vis à vis du coin, ont été détruites comme je viens de le dire. ces couches là ou elles sorte que l'on peut comparer toutes les couches de la montagne à celles d'un jeu de cartes ployé en deux suivant sa longueur.» in considering the chains of the jura, on the west side of that which looks to the lake, our author has the following interesting observations, p. . «les chaînes dont il est composé, à mesure qu'ils s'éloignent de la haute ligne orientale perdent graduellement de leur hauteur et de leur continuité; le plus occidentales ne forment pas, comme la premiere, des chaînes de montagnes élevée et non interrompues; ce sont des monticules allongés il est vrai, mais isolés ou qui du moins ne sont unis que par leurs bases. «§ . leur structure n'est pas la même dans toute l'étendue du jura. la forme primitive la plus générale ressemble cependant à celles de la haute chaîne; c'est-à-dire, que ce sont de voûtes, composées et remplies d'arcs concentriques. «c'est surtout entre pontarlier et besançon, que l'on rencontre des collines qui ont régulièrement cette structure. la grande route traverse de larges vallées, dans lesquelles les couches sont horizontales; mais ces vallées sont séparées par des chaînes peu élevées dont le couches arquées montent jusques au haut de la montagne, et descendent ensuite du coté opposé. on en voit aussi de la même forme dans la prévôté de moutier grand val. la birs traverse des rochers qui offrent à découvert la construction intérieure des montagnes; les couches de roc forment dans cet endroit des voûtes élevées l'une sur l'autre en suivant le contour extérieur de la montagne.--_dict. géog. de la suisse, tom._ . _p._ . «d'autres fois le sommet de la montagne est plus aigu que n'est celui d'une voûte, et les couches paralelles entr'elles, mais inclinées à l'horizon en sens contraire, présentent dans leur section, la form d'un chevron ou d'un lambda [greek: l]. «§ . mais cette même structure presente fréquemment une singularité remarquable. ce sont des bancs perpendiculaires à l'horizon qui occupent à-peu-pres le milieu ou le coeur de la montagne et qui séparent les couches d'une des faces de celles de la face opposée. «j'ai observé plusieurs montagnes secondaires, et du jura et d'ailleurs, et surtout un grande nombre de montagne primitive, dont la structure est la même[ ].» [footnote : this correspondency in the shape of the primitive and secondary mountains of our author, of which the structure is the same, is an important observation for our theory, which makes the origin of those two different things to be similar; it is inconsistent, however, with the notion of primitive parts, which some philosophers have entertained.] «§ . les couches perpendiculaires à l'horizon, que l'on rencontre fréquemment dans le jura ont presque toutes leurs plans dirigés du nord-nord-est au sud-sud-ouest, suivant la direction générale de cette chaîne de montagne. cette observation est d'une assez grande importance parce qu'elle exclut ou rend du moins improbable l'idée d'un bouleversement. «j'ai cru pendant long-temps que toutes les couches dévoient avoir été formées dans une situation horizontale, ou peu inclinée à l'horizon, et que celles que l'on rencontre dans une situation perpendiculaire, ou très-inclinées, avoient été mises dans cet état par quelque révolution; mais à force de rencontrer des couches dans cette situation, de les voir dans de montagnes bien conservées, et qui ne paroissoient point avoir subi de bouleversement, et d'observer une grande régularité dans la forme et dans la direction de ces couches; je suis venu à penser que la nature peut bien avoir aussi formé de ces bancs très-inclinés, et même perpendiculaire à la surface de la terre.» here the reasoning of our author is sufficiently just; he sees too much order in the effect to ascribe it to a cause merely fortuitous. but surely nothing in those appearances hinders the conclusion, that the strata now found in ail possible positions, had been originally horizontal when at the bottom of the sea, and that they had been afterwards regularly bent and broken, by the same cause which operated in placing them above the level of the ocean. the force of this argument will appear, by considering the various regular and irregular positions in which they are found. «§ . dans quelques endroits du jura, on voit des espèces de demi-cirques formés par des rochers dont le couches sont de portions de la surface d'un même cône et tendent à un centre commun élevé au dessus de l'horizon. «ainsi auprès de pontarlier, etc. «§ . mais il est bien plus fréquent de voir des montagnes dont les couches ont la forme d'une demi-voûte, et qui vues de profil présentent, comme notre montagne de saleve, un pente douce d'une coté, et des escarpemens de l'autre. «plusieurs vallées du jura sont situées entre deux chaine de montagnes qui ont cette forme, et qui se presentent réciproquement leur faces escarpées. on croit même apercevoir quelque correspondance, entre les couches de ces montagnes opposées, et l'on diroit qu'elles furent anciennement unies, et que la partie intermédiaire a été détruite, ou que la montagne s'est fendue du haut en bas, et que ses deux moitiés se sont écartées pour faire place à la vallée qu'elles renferment. «§ . pour résumer en peu de mots les idées que je me forme de la structure du jura; je dirai que je crois qu'il est composé de différentes chaînes à-peu-près paralleles entr'elles, et à celles des alpes, mais tirant un peu plus du nord au midi: que la chaine la plus élevée et la plus voisine des alpes, a eu originairement la forme d'une dos d'âne dont les pentes partent du faite, recouvrent les flancs, et descendent jusques au pieds de la montagne: que les chaînes suivantes du coté de l'ouest, sont composées de montagnes graduellement moins élevées et moins étendues; que les couches de ces montagnes ont généralement la forme de voûtes entières ou de moitié de voûtes; et qu'elles viennent mourir dans des plaines, qui ont pour base des bancs calcaires tout à fait horizontaux de la même nature que ceux du mont jura, et qui furent peut-être anciennement continus avec eux.» our author has here described most accurately, not only the present shape and positions of particular strata, but the general shape and structure of the land him the saleve and jura, which are not in the alps, to the plains of france, where the strata are generally in a more horizontal situation. having thus seen the structure of what are commonly termed the secondary mountains, a structure which prevails generally in all parts of the land, at least in all that which is not primitive in the estimation of naturalists, who suppose a different origin to different parts, it will now be thought a most interesting view of nature, to see the same accurate examination of the structure of the earth, from those secondary mountains of geneva to the center of the alps, where we find such a variety of mountains of different materials, (whether they shall be called primitive or secondary) and where such opportunity is found for seeing the structure of those mountains. for, if we shall find the same principles, here prevailing in the formation of those supposed primitive mountains as are found over all the earth in general, and as are employed in fashioning or shaping every species of material, it will be allowed us to conclude, that, in this situation of things, we have what is general in the formation of land, notwithstanding imaginary distinctions of certain parts which had been formed one way, and of others which are supposed to be operations of an opposite nature. this question therefore will be properly decided in our author's journey to the alps; for, if we shall there find calcareous strata perfectly consolidated, as they should be by the extreme operation of subterranean heat and fusion; if we find materials of every species formed after the manner of stratification; and if all those different strata variously consolidated shall be found in all positions, similar to those which we have now seen in the examination of the jura and saleve, with this difference, that the deplacement and contorsion may be more violent in those highly consolidated strata, we shall then generalise an operation by which the present state of things must have been produced; and in those regular appearances, we shall acknowledge the operation of an internal heat, and of an elevating power. «§ . les pentes rapides des bancs dont est formé le mole, les directions variées de ces mêmes bancs sont aussi conformes à une observation générale et importante, que le montagnes secondaires sont d'autant plus irrégulières et plus inclinées qu'elles s'approchent plus des primitives. «a la verité, quelque montagnes calcaires même à de grandes distances des primitives ont ça et là des couches inclinées et même quelquefois verticales; mais ces exception locales n'empêchent pas qu'il ne soit vrai qu'en general, les bancs calcaires, que l'on trouve dans les plaines qui sont éloignées des hautes montagnes, ont leurs bancs ou horizontaux ou peu inclinés; tandis, qu'au contraire, les montagnes qui s'approchent, du centre des grands chaînes, n'ont que très-rarement des couches horizontales, et presentent presque par-tout des couches fortement et diversement inclinées.» that is to say, that there is no place of the earth, however plain and horizontal in general may be the strata, in which examples are not found of this manner of disordering or displacing strata; at the same time they are more crested and more disordered in proportion to the mountainous nature of the country. here is the proposition contained in that general observation of natural history; and this is a proposition which either naturally flows from the theory, or is perfectly consistent with it. «§ , a. le rocher dont j'ai parlé (§ ) qui touche celui de la dole, et qui porte le nom de vouarne, est d'une structure singulière. les bancs dont il est composé sont escarpés, les uns en montant contre le nord-est sous un angle de à degrés; les autres en s'élevant contre le sud-est. «§ . en avant de ce rocher, du coté l'est, on en voit un autre d'une structure très remarquable. il a la forme d'un chevron aigu ou d'un lambda [greek: l]. on le nomme, sans doute à cause de sa forme, le rocher de fin château. les bancs dont il est composé sont très inclinés à l'horizon, et s'appuient réciproquement contre leurs sommités respectives. les planches que l'on dresse en appui les unes contre les autres pour les faire secher, peuvent donner une idée de la situation de les bancs. cette forme n'est pas rare dans ces rochers calcaires; mais elle est bien plus fréquente encore, et plus décidée dans le rochers primitifs, comme nous le verrons dans la suite. «le rocher de fin château presente dans cette forme même une circonstance très-remarquable; c'est que l'intervalle que les jambes du lambda [greek: l] laissent entr'elles, est rempli par des couches perpendiculaires à l'horizon. on diroit que ces couches chassées en haut par une force souterraine, ou soulevé de part et d'autre, des bancs qui sont demeurés appuyés contre elles. nous avons déjà vu des rochers de cette forme, § .» here the truth of our theory is so evident, that this philosopher naturally acknowledges it without intention. in his journey to mont blanc, he observes, page , «un peu au delà de contamine on passe sous les ruines du château de faucigny, bâti sur le sommet d'un rocher escarpé, qui fait partie de la base du môle. tant qu'on est immédiatement au dessous de ce rocher on ne démêle pas bien sa structure; mais après l'avoir passe, on peut voir à l'aide d'une lunette, qu'il est composé de couches perpendiculaires à l'horizon, et dirigées du nord-est au sud-ouest. au dessous de ce rocher au sud-est, on voit d'autres couches verticales, mais dont les plans coupent à l'angle droits ceux des premiers. «a une bonne demi-lieue de ce château on observe, comme au pied du mont saleve, une masse de rochers, dont les couches minces, presque perpendiculaires à l'horizon, sont adossées aux escarpemens de couches épaisses et bien suivies, qui paroissent horizontales.» speaking of the mont brezon, our author says, page , «mais le pied de cette montagne est encore, comme celui de saleve, couvert de grandes couches presque perpendiculaires à l'horizon et appuyées contre le corps même de la montagne. et quoique le brezon se termine â une petite demi-lieue de la bonne ville, cependant ses couches qui sont appuyées contre le pied de la chaîne méridionale, et qui tournent ainsi le dos à l'arve, continuent de régner jusques au village de siongy pendant l'espace de prés de deux lieues. elles sont à la verite coupées par une petite vallée à l'extrémité du pied du brezon, mais elles recommencent au de là de cette coupure. «§ . cette petite vallée, qui s'ouvre au pied du brezon, est étroite et tortueuse; les angles saillans engrenées dans les angles rentrans y sont extrêmement sensibles. elle conduit au village de brezon, qui est situé derrière la montagne de ce nom. «au dessus de ce village sont de grands et beaux pâturages avec des chalets qui ne sont habités qu'en été, et que l'on nomme les granges de solaison. c'est là que j'allois coucher quand je visitois le brezon et les montagnes voisines. les granges de solaison sont dominées, au sud-est par le monts vergi, chaîne calcaire très élevée, dont j'ai aussi parcouru les sommets qui se voyent des environs de genève, sur la droite du môle. «cette chaîne court du nord-est au sud-ouest, et vient se terminer derrière les montagnes qui bordent notre route à droite. «§ . on peut, des environs de siongy, observer la structure de la dernière montagne de cette chaine; elle est très remarquable. les couches horizontales au sommet se courbent presqu'à angles droits, et descendent de là perpendiculairement du coté du nord-ouest. on diroit qu'elles ont été ployées par une violent effort; on les voit séparées et éclatées en divers endroits. «§ . le mole se termine à la jonction du giffre avec l'arve; ses dernières couches descendent avec rapidité dans le lit de cette petite riviere, «les montagnes qui suivent le môle, et qui forment après lui le coté septentrional de la vallée de l'arve, sont basses et indifférentes, une seule est remarquable par sa forme pyramidale, et par ses couches qui convergent á son sommet, et lui donnent la forme d'un chevron. «§ . la ville même de cluse est bâtie sur le pied d'une montagne, dont la structure est très extraordinaire; on en juge mieux à une certain distance que de la ville même. «cette montagne de forme conique émoussée, ou plutôt parabolique, est pour ainsi dire coiffée d'une bande de rochers, qui du haut de sa tête descendent à droite et à gauche jusques à son pied. ces rochers nuds sont relevées par le fond de verdure dont le reste de montagne est couverte. ils sont composés de plusieurs bandes parallèles entr'elles; les extérieures sont blanches et épaisses, les intérieures sont brunes et plus minces. le corps même de la montagne, dont on apperçoit çà et là les rochers au travers du bois, qui les couvre, paroi composé de couches irrégulières et diversement inclinées. on pourroit soupçonner que cette bande n'est que le reste d'une espèce de callote qui vraisemblablement couvroit autrefois toute la montagne. «§ . des que l'on est sorti de la ville de cluse, on voit en se retournant sur la droite, les rochers en surplomb sous lesquels on a passé avant de traverser l'arve. on distingue d'ici le profil des couches de ces rochers; et on reconnoit qu'elles sont presque perpendiculaires à l'horizon. «ces couches sont adossées à d'autres couches calcaires et verticales comme elles, mais qui sont la continuation de couches à-peu-près horizontales: on diroit qu'une force inconnue a ployé à angles droits l'extrémité de ces couches, et les a ainsi contrainte à prendre une situation verticale. «§ . si du grande chemin qui est au pied de la caverne, on jette les yeux sur le rocher dans lequel est son ouverture, on observera que les bancs de ce rocher sont très épais, et composés d'une pierre calcaire grise; qu'au dessus cette pierre grise on en voit une autre de couleur brune, dont les couches font très minces; mais qui par leur répétition forment une épaisseur considérable. «ces couches de pierres à feuillets minces, continuent jusques à sallanches et au de là; et sont renfermées par dessus et par dessous entre des bancs de pierre grise compacte et à couches épaisses. quelquefois la pierre grise qui sert de base, ou comme disent les mineurs, de plancher à la brune, s'enfonce et alors celle-ci paroit à fleur de terre; ailleurs cette pierre grise se relève et porte la brune à une grande hauteur. «cette pierre brune et feuilletée est comme la grise de nature calcaire; mais un mélange d'argile, et peut-être un peu de matière grasse ou phlogistique lui donnent sa couleur brune et la disposent à se rompre en fragmens angulaires et à cotés plans. «ce genre de pierre est fort sujet à avoir ses couches fléchies ou ondées en forme de s de z ou de c. près de la caverne, on, voit une lacune dans le milieu des bancs du roc gris; les couches minces ont rempli cette lacune, mais elles sont dans cet espace extrêmement tourmentées. on comprend que ce vide et ce remplacement, se sont faits dans le temps même de la formation de ces rochers.» we have the following description of the cascade mountain, p. . «les couches de cette montagne sont la continuation des couches supérieures du rocher de la cascade, et forment des arcs concentriques, tournés en sens contraire; en sorte que la totalité de ces couches a la forme d'une s, dont la partie supérieure se recourbe fort en arrière. «le rocher de la cascade, représenté par la planche iv. est tout calcaire; les couches, qui sont au dessous des lettres d et e, sont composées de ce roc gris compact dont les bancs, comme nous l'avons vu plus haut, sont ordinairement épais, mais les couches extérieures entre e et f, sont du roc brun à couches minces, dont nous avons aussi parlé. ces même couches minces se voyent encore à l'intersection de perpendiculaire qui passent par lettres a et e. «ici dont c'est le roc gris qui est renfermé entre deux bancs de roc brun au lieu qu'auprès de la caverne, c'étoit le roc brun, qui étoit resserré entre deux bancs de roc gris; mais cette différence n'est pas ce qu'il y a de plus difficile à expliquer; c'est la forme arquée de ces grandes couches dont il faudroit rendre raison.» having measured this rock geometrically, the result is as follows: «le plus grand des arcs de cercle que forment ces couches extérieures de ce rocher, a donc pour corde une ligne d'environ pieds: dans toute cette étendue, ces couches de même que les intérieures sont suivies sans interruption. «je dois cependant avertir, qu'en avant du rocher de la cascade à la hauteur de la lettre a, et au dessous, on voit des couches détachées des circulaires, et indépendantes d'elles; ce sont de plans inclinés en appui contre le corps de la montagne, semblables à ceux que j'ai observé au pied du mont saleve, et d'une formation vraisemblablement plus récente que le corps même de la montagne. «mais derrière ces plans, on voit les couches arquées, qui sont horizontales dans le bas, servir de base au rocher, se relever ensuite sur la droite, et venir en tournant former le faite de ce même rocher.» «it may be interesting to hear our author's reasoning upon this subject, more especially as it will give more faith or light, if it were possible, to his descriptions, which are irreproachable. «§ . il s'agiroit à present de dire quelle force a pu donner à ces couches cette situation; comment elles out pu être retroussées de façon que les plus basses soient devenues les plus élevées? «la première idée qui se présente est celle des eaux souterrains. ce qui pourroit même faire soupçonner que ces couches ont été réellement relevées par une force souterraine c'est que, sur la droite du rocher qu'elles forment, il y à un vide ou il manque à peu-pres ce qu'il faudroit pour former la hauteur de la cascade; car la montagne que l'on voit sous les lettres g et h, est sur une ligne beaucoup plus reculée. sur la droite de ce vide ces couches recommencent sur la ligne de celles qui sont recourbées; on les voit coupées à pic de leur coté, avec les mêmes couleurs, la même épaisseur, mais dans une situation horizontale. «j'ai observé dans plus d'une montagne des couches ainsi retroussées, aupres desquelles on voit le vide qu'elles paroissent avoir laissé en se repliant sur elles mêmes. «dans l'ober hasli la vallée de meiringen au dessus du village de stein. «dans le canton de uri, sur le bords du lac de lucerne, on en voit aussi plusieurs exemples bien distincts. «une montagne plus rapprochée de notre cascade, et qui presente aussi ce phénomène, est située derrière elle au nord-est entre le village de seiz et les granges des fonds. cette montagne porte le nom d'anterne. elle est plus élevée que celle du nant d'arpenaz, ses couches forment des arcs concentriques plus grands et plus recourbés encore, et l'on voit de même à leur droite un vide qu'elles semblent avoir laissé en se levant et se repliant sur la gauche. «mais malgré ces observations, ce n'est pas sans peine que j'ai recours à ces agens presque sur-naturelles, sur-tout quand je n'aperçois aucun de leurs vestiges; car cette montagne et celle d'alentour ne laissent apercevoir aucune trace du feu. je laissé donc cette question en suspens; j'y reviendrai plus d'une fois, et même avant la fin de ce chapitre. «il faut à present jetter un coup-d'oeil sur les montagnes de l'autre coté de l'arve. «§ . vis-à-vis de la cascade de l'autre coté de la rivière, on voit un chaine de montagnes extrêmement élevées, qui présentent leurs escarpemens au dessus de sallenche, et contre le mont blanc. leurs couches descendent par conséquent vers la vallée du reposoir, située à leur pied au nord-ouest. «mais au pied des escarpemens de cette même chaine, on voit une rangée de bases montagnes paralleles à sa direction, inclinées en appui contre ses escarpemens et qui descendent en pente douce vers sallenche; de même encore une fois qu'au mont saleve. «§ . de la cascade jusques à st martin, on voit fréquemment à sa gauche des couches singulièrement contournées, et toujours dans cette espèce de pierre calcaire brune que nous suivons depuis si long-tems. quelques-unes de ces couches forment presqu'un cercle entier, les plus remarquables sont à une demi-lieue de la cascade. elles représentent des arcs dont les convexités se regardent à peu près comme dans un x; mais avec des plans situes obliquement entre les deux convexités, et des couches planes et horizontales immédiatement au-dessus de l'arc de la gauche. «ces diverses couches sont si bien suivies dans tous leurs contours, et si singulièrement entrelacées que j'ai peine à croire qu'elles ayent été formées dans une situation horizontale, et qu'ensuite des bouleversemens leur ayent donné ces positions bizarres. «déjà il faudroit supposer que ces bouleversemens se sont faits dans un tems ou ces couches étoient encore molles et parfaitement flexibles, car on n'y voit rien de rompu, leurs courbures, même les plus angulaires, sont absolument entières. «ensuite il faudroit, que ces couches, dans cet état de mollesse, eussent été froissées et contournées d'une maniere tout-à-fait étrange, et presqu'impossible à expliquer en détail. d'ailleurs des explosions souterraines rompent, déchirent, et ne soulèvent pas avec le ménagement qu'exigeroit la conservation de continuité de toutes ces parties. «la crystallization peut seul, à mon avis, rendre raison de ces bizarreries; nous voyons, comme je l'ai déjà dit, des albâtres formés pour ainsi dire sous nos yeux par de vrayes crystallizations dans les crevasses, et dans les cavernes des montagnes, presenter des couches dans lesquelles on observe des jeux tout aussi singuliers[ ].» [footnote : m. de saussure would explain the various shape and contortions of strata upon the principles of crystallization; but surely he has not adverted to the distinction of crystallization as an operation giving form or shape, and as giving only solidity or hardness, which last, it is apprehended, is the only sense in which our author here considers crystallization, although, from the way in which he has employed this principle, it would seem that it is the figure which is to be explained by it. this conjecture is supported by the example of alabaster or _stalactites_, with which he compares the section of those mountains; for, in the example of implicated figures of the stalactite marble, similar to those of the present distorted strata, crystallization has nothing to do with that part of the figure which corresponds to the case now under consideration; it forms indeed certain figures of crystals in the mass by which also the configuration of some minute parts, affected by those crystals, is determined; but the figure of those alabasters, which is to be compared with the present subject, arises solely from the current of petrifying water along the surface of the mass. this mass, therefore, being formed by succession from that water, crystallising calcareous earth, and carrying colouring parts of other earth, gives an appearance of stratification to a figure which is absolutely inconsistent with stratification; an operation which is performed by depositing materials at the bottom of the sea, and which the marine bodies contained in some of the strata sufficiently attest.] «je ne repugnerois donc pas à croire que le rocher de la cascade a pu être formé dans la situation dans laquelle il se presente; si ce vuide à sa droite, ses couches qui, bien que suivies, montrent pourtant quelques ruptures dans les flexions un peu fortes, et ses grands bancs de cette pierre grise compacte, qui n'est point si sujette à ces formes bizarres, n'éstablissoient pas une difference sensible entr'elles et celles que nous venons examiner.» it is impossible to be more impartial than m. de saussure has proved himself to be on this occasion, or to reason more in the manner in which every philosopher ought to reason on all occasions. but to see the full value of this author's impartiality, notwithstanding of his system, let us follow him in the second volume of voyages dans les alpes. it is in chap. xx. entitled, poudingues de valorsine, that we find the following description, with his reasoning upon that appearance. «on voit la (page .) que la base de cette montagne est un vrai granit gris à grains médiocres, et dont la structure n'a rien de distinct; mais au-dessus de ces granits on trouve des roches feuilletées quartzeuses mélangées de mica et de feldspath genre moyenne entre le granit veiné et la roche feuilletée ordinaire. leurs couches courent du nord au sud, comme la vallée de valorsine, et font avec l'horizon un angle de degrés, en s'appuyant au couchant contre cette même vallée. ces roches continuent dans la même situation jusques à ce qu'apres une demi-heure de marche, on les perd de vue sous la verdure qui tapisse une petite plaine, située au milieu des bois, et qui se nomme le _plan des cebianes_. «§ . de-là, en montant obliquement du coté du sud, on rencontre de grands blocs d'un schiste gris ou de couleur de lie-de-vin, quelquefois même d'un violet decidé, qui renferment une grande quantite de cailloux étrangers, les uns angulaires, les autres arrondis, et de différentes grosseurs, depuis celle d'un grain de sable jusqu'à celle de la tête. je fus curieux de voir ces poudingues dans leur lieu natal; je montai droit en haut pour y arriver; mais là quel ne fut pas mon étonnement de trouver leur couches dans une situation verticale! «§ . on comprendra sans peine la raison de cet étonnement si l'on consideré qu'il est impossible que ces poudingues aient été formées dans cette situation. «que des particules de la plus extrême ténuité, suspendues dans un liquide, puissent s'agglutiner entr'elles et former des couches verticales, c'est ce que nous avons la preuve en fait dans les albâtres, les agathes, et même dans les crystallizations artificielles. mais qu'une pierre toute formée, de la grosseur de la tête, se soit arrêtée au milieu d'une parois verticale, et ait attendu là que les petites particules de la pierre vinssent l'envelopper, la souder et la fixer dans cette place, c'est une supposition absurde et impossible. il faut donc regarder comme une chose démontrée, que ces poudingues ont été formés dans une position horizontale, ou à peu-près telle, et redressés, ensuite après leurs endurcissement. quelle est la cause qui les a redressés? c'est ce que nous ignorons encore; mais c'est déjà un pas, et un pas important, au milieu de la quantité prodigieuse de couches verticales que nous rencontrons dans nos alpes, que d'en avoir trouvé quelques-unes dont on soit parfaitement sûr qu'elles ont été formées dans une situation horizontale. «§ . la nature même de la matière qu'enveloppe les cailloux de ces poudingues rend ce fait plus curieux et plus décisif. car si c'étoit une pâte informe et grossière, on pourroit croire que ces cailloux et la pâte qui les lie ont été jetés pêle-mêle dans quelques crevasses verticales, où la partie liquide c'est endurcie par le dessèchement. mais bien loin de-là, le tissu de cette pâte est d'une finesse admirables; c'est une schiste, dont les feuillets élémentaires sont excessivement minces, mêlés de mica, et parfaitement parallèles aux plans qui divisent les couches de la pierre. ces couches mêmes sont très-régulières, bien suives et de différentes épaisseurs, depuis une demi pouce jusques à plusieurs pieds. celles qui sont minces contiennent peu et quelquefois point de cailloux étrangers, et on observe quelques alternatives de ces couches minces sans cailloux et des couches épaisses qui en contiennent. la couleur du fond de ce schiste varie beaucoup; il est ici gris, là verdâtre, le plus souvent violet ou rougeâtre; on en voit aussi qui est marbré de ces différentes couleurs. ses couches sont dirigées du nord au sud exactement comme celles des roches granitoïdes qui sont au-dessous, § . mais l'inclinaison du schiste est beaucoup plus grande, ses couches sont souvent tout-à-fait verticales, et lorsqu'elles ne le sont pas, elles montent de quelques degrés du même coté que les roches dont je viens de parler; c'est-à-dire, du coté de l'ouest. «§ . les cailloux enclavés dans ce schiste sont, comme je l'ai dite, de différentes grandeurs, depuis celle du grain de sable, jusques à ou pouces de diamètre; ils appartiennent tous à la classe des roches que j'appelle primitives; je n'y ai cependant pas vu de granit en masse; seulement des granits feuilletés, des roches feuilletées, mélangées de quartz et de mica; des fragmens même de quartz pur; mais absolument aucun schiste purement argileux, ni aucune pierre calcaire, rien qui fît effervescence avec l'eau-forte, et la pâte même qui renferme ces cailloux n'en fait aucune. leur forme varie; les uns sont arrondis et ont manifestement perdu leurs angles par le frottement; d'autres ont tous leurs angles vifs, quelques uns même ont la forme rhomboïdale qu'affectent si fréquemment les roches de ce genre. dans les parties de la pierre ou ces cailloux étrangers sont entassés en très-grand nombre, les élémens du schiste n'ont pas eu la liberté de s'arranger et de former des feuillets parallèles; mais par-tout où les cailloux laissent entr'eux des intervalles sensibles, les feuillets reparoissent, et sont constamment paralleles, et entr'eux et aux plans qui divisent les couches. «§ . les bancs de ces schistes poudingues forment dans la montagne une épaisseur d'environ cent toises, comptées de l'est à l'ouest transversalement aux couches, et je l'ai suivie dans le sens de la longueur l'espace de plus d'une lieue; on ne peut pas la suivre plus long-temps, parce que les bancs se cachent et s'enfoncent sous la terre.» here m. de saussure, who is always more anxious to establish truth, than preserve theory, gives up the formation of the alpine strata by crystallization. let us now see how he acknowledges the evidence of softness in those strata. it is in his description of the val de mont joye, tom. d. page . «ce sont des roches dures à fond de quartz, ou de feldspath blanc, confusément cristallisé, avec des veines noires de mica ou de schorl en petites lames. ces veines, qui pénètrent tout au travers de la pierre, sont la section des couches dont elle est composée; on les voit, ici planes et parallèles, entr'elles; la en zig-zags, renfermés entre de plans parfaitement parallèles; accident dont les étoffes tout-à-la-fois rayées et chinées donnent encore le dessin. ces anfractuosités des couches sont-elles un effect de la crystallization, ou bien d'un mouvement de pression qui a refoulé des couches planes lorsqu'elles étoient encore flexibles, après quoi d'autres couches planes sont venues se former sur elles.» m. de saussure has no idea of strata formed at the bottom of the sea, being afterwards softened by means of heat and fusion. he had already given up the supposition of those vertical or highly inclined strata having been formed in their present position; but had this geologist seen that it was the same cause by which those strata had both been raised in their place and softened in their substance, i am persuaded that he would have freely acknowledged, in this zig-zag shape, which is so common in the alpine strata, the fullest evidence of the softening and the elevating power. at the _tour de fols_, near st bernard, m. de saussure found an appearance the most distinct of its kind, and worthy to be recorded as a leading fact in matters of geology. _voyages dans les alpes_, tome d. pag. . «la direction général des couches de ces rochers et des ardoises qui les séparent, est donc du midi au nord, ou plus exactement du sud-sud-ouest au nord-nord-est; mais cette direction est coupée à angles droits par des couches d'ardoises et de feuillet quartzeux, qui passent du levant au couchant par le milieu des couches qui courent du midi au nord.» clearly as this fact must demonstrate, to a reasoning person, the fracture and dislocation of strata, our author, who knows so well the reasoning of naturalists on such an occasion, gives us his opinion as follows: «quant à la raison de ce fait, on peut l'attribuer à de boulversemens, et c'est ce qui me paroît le plus vraisemblable. on pourroit cependant supposer qu'il existoit au milieu de ces couches une grande fissure, qui a été remplie par des couches transversales. mais il faudroit pour cela que ce remplissage se fût fait dans le temps même de la formation de ce montagne, puisque les ardoises et les pyramides quartzeuses, donc la direction est transversales, sont précisément de la même nature que les autres; et il faudrait encore supposer, qu'elles ont été formées dans la situation très-inclinée qu'on leur voit aujourd'hui; supposition que l'on aura quelque peine à admettre.» in this second volume, m. de saussure gives us a general view with regard to the mountains which border the valley of the rhône, p. . «§ . cette suite de montagnes calcaire que nous avons côtoyée depuis st maurice jusques à chillon, ne presente presque nulle part des couches régulières et horizontales: elles sont presque par-tout inclinées, fléchies, et paroissent avoir été tourmentées par des causes violentes: car de simples affaissemens ne suffisent pas à mon gré pour rendre raison de toutes leurs formes. leurs escarpemens sont aussi assez irrégulièrement situés; la plus grande partie d'entr'eux paroît cependant tournée du côté de la vallée du rhône. «la suite des montagnes qui correspond à celle-ci sur la rive gauche du rhône et du lac est aussi calcaire, et à-peu-pres aussi irrégulière. la plupart de ces montagnes, celles surtout qui sont les plus voisines du lac, sont escarpées, et du coté du lac et de celui du rhône. les vallées qui les séparent paroissent les diviser en chaînes paralleles au lac, qui courent du nord-est au sud-ouest. les plus voisines du lac sont escarpées contre lui, comme je viens de le dire, tandis que les plus éloignées du lac, ou les plus proches du centre des alpes, sont inclinées contre ces mêmes alpes. _le val de lie_ sépare ces deux ordres de montagnes: cette vallée riche et fertile a la forme d'un berceau; les deux chaînes qui la bordent s'élèvent en pente douce de son côté, et tournent leurs escarpemens, l'une contre le lac, l'autre contre les alpes; au reste je n'ai point parcouru ces montagnes, je n'ai pu en juger qu'en les observant de loin. «mais ce dont on peut être certain, c'est que, si les montagnes qui bordent ces deux rives de la vallée du rhône, se ressemblent par leur nature, qui est calcaire de part et d'autre elles ne se ressemblent point par leur structure. on n'y voit aucune correspondance, ni dans les positions, ni dans les formes: les vallées qui les séparent ne se correspondent pas non plus. ce défaut de correspondance me paroît encore réveiller l'idée des bouleversemens.» the general result, from these observations of our author, is this. first, there is no distinction to be made of what is termed primary and secondary mountains, with regard to the position of their strata; every different species of stratum, from the stratified granite and quartzy _schistus_ of the alps to the _oolites_ of the jura and saleve, being found in every respect the same; whether this shall be supposed as arising from their original formation, or, according to the present theory, from a subsequent deplacement of strata formed originally in a horizontal situation. secondly, it appears that, in all those alpine regions, the vertical position of strata prevails; and that this appearance, which seems to be as general in the alpine regions of the globe as it is here in the mountainous regions of the alps, has been brought about both by the fracture and flexure of those masses, which, if properly strata, must have been originally extended in planes nearly horizontal. whereas, in descending from that mountainous region towards the more level country of france, the same changes in the natural position of strata are observed, with this difference, that here they are in a less degree. now that those vertical strata had been originally formed at the bottom of the sea is evident from this author's observation, which has been already referred to (vol. st, page ). thirdly, in all those accurate observations of a naturalist, so well qualified for this purpose, there appears nothing but what is perfectly consistent with such a cause as had operated by slow degrees, and softened the bodies of rocks at the same time that it bended them into shapes and positions inconsistent with their original formation, and often almost diametrically opposite to it; although there appeared to our author an insurmountable difficulty in ascribing those changes to the operation of subterranean fire, according to the idea hitherto conceived of that agent. this grand mineral view of so large a tract of country is the more interesting, in that there has not occurred the least appearance of volcanic matter, nor basaltic rock, in all that space, where so great manifestation is made of those internal operations of the globe by which strata had been consolidated in their substance, and erected into positions the most distant from that in which they had been formed. it is peculiarly satisfactory to me, and i hope also to my readers, to have the observations of so able a philosopher and so diligent a naturalist to offer in confirmation of a theory which had been formed from appearances of the same kind in a country so far distant from those of our author now described, as are the alps of savoy from those of scotland. it gives me a singular pleasure, in thus collecting facts for the support of my opinion, to contribute all i can to recommend the study of a work in natural history the most exemplary of its kind; and a work which will remain the unalterable conveyance of precious information when theories making a temporary figure may be changed. to a person who understands the present theory, there can be no occasion here to give the particular applications which will naturally occur in reading those various descriptions. in these examples are contained every species of bending, twisting, and displacement of the strata, from the horizontal state in which they had been originally formed to the vertical, or even to their being doubled back; and although m. de saussure had endeavoured to reason himself into a belief of those inverted strata having been formed in their present place, it is evident that he had only founded this opinion upon a principle which, however just, may here perhaps be found misplaced; it is that of not endeavouring to explain appearances from any supposition of which we have not full conviction. i flatter myself, that when he shall have considered the arguments which have here been employed for the manifold, the general operations of subterranean fire, as well as for the long continued operations of water on the surface of the erected land, he will not seek after any other explanation than that which had naturally occurred to himself upon the occasion, and which he most ingenuously declares to have great weight, although not sufficient to persuade him of its truth. chap. ii. _the same subject continued, with examples from different countries._ our theory, it must be remembered, has for principle, that all the alpine as well as horizontal strata had their origin at the bottom of the sea, from the deposits of sand, gravel, calcareous and other bodies, the materials of the land which was then going into ruin; it must also be observed, that all those strata of various materials, although originally uniform in their structure and appearance as a collection of stratified materials, have acquired appearances which often are difficult to reconcile with that of their original, and is only to be understood by an examination of a series in those objects, or that gradation which is sometimes to be perceived from the one extreme state to the other, that is from their natural to their most changed state. m. de saussure who will not be suspected of having any such theory in his view, will be found giving the most exemplary confirmation to that system of things. i would therefore beg leave farther to transcribe what he has observed most interesting with regard to that gradation of changed strata. it is in the high passage of the bon-homme, tom. . p. . «depuis le col, dont je viens de parler, jusqu'a la croix, qui suivant l'usage, est placée au point le plus élevé du passage, on a trois quarts de lieue, ou une petite heure de route, dans laquelle on traverse des grès, des brèches calcaires, des pierres calcaires simples de couleur grise, d'autres calcaires bleuâtres et des ardoises: ces alternatives se répètent à plusieurs reprises. parmi ces grès on en trouve qui renferment des cailloux roulés, et qui font effervescence avec les acides; d'autres qui ne renferment point de cailloux, et qui ne font point d'effervescence. «quelques-uns de ces grès m'out paru remarquables par leur ressemblance avec des roches feuilletées; ils sont compactes mêlés de mica; un suc quartzeux remplit tous les interstices de leurs grains, et leur donne une dureté et une solidité singuliers; il n'y a personne, qui en voyant des morceaux détachés de cette pierre, ne la prît pour une roche feuilletée; mais quand on la trouve dans le lieu de sa formation, et qu'on voit les gradations qui la lient avec des grès indubitables, par exemple avec ceux qui renferment des cailloux roulés, on ne peut plus douter de sa nature. ces couches sont en général inclinées de degrés en descendant au sud-est.» our author would here make a distinction of the _roche feuilletée_ and the _grès_; the one he considers as primitive, and as having had an origin of which we are extremely ignorant; the other he considers as a secondary thing, and as having been formed of sand deposited at the bottom of moving water, and afterwards becoming stone. this great resemblance, therefore, of those two things so different in the opinion of naturalists, struck him in that forcible manner. nothing can be a stronger confirmation of the present theory, which gives a similar origin to those two different things, than is the observation of so good a naturalist, finding those two things in a manner undistinguishable. he thus proceeds: «j'ai vu dans les vosges de très-beaux grès du même genre; ils ne ressembloient cependant pas autant à des roches primitives, parce qu'ils ne contenoient pas de mica. mais ce qu'il y a ici de plus digne d'attention, et que l'on ne voit point dans les vosges, c'est de trouver des grès de cette nature renfermés entre des bancs de pierre calcaire. cependant plus ces grès s'éloignent de la roche primitive, qui forme la base de la montagne, et moins ils sont solides et quartzeux jusqu'à ce qu'enfin les plus élevés font effervescence avec l'eau-forte.» here again the alpine lime-stones, which, according to the present naturalists, should be primitive, are plainly homologated in their origin with strata formed of sand. our author proceeds, (p. ,) § , «le haut du passage du bon-homme, au pied de la croix est d'ardoises minces mêlées de feuillets de quartz. en descendant au chapiu, on trouve ces mêmes ardoises alternant avec des couches de grès mince feuilleté, mêlé de mica, puis des calcaires simples, puis des brèches calcaires qui renferment des fragmens calcaires à angles vifs. toutes ces couches descendent au sud-est suivant la pente de la montagne, mais avec un peu plus de rapidité. «comme cette montagne est absolument dégarnie d'arbres, on y voit d'un coup-d'oeil les progrès de l'action des eaux. des sillons à peine visibles dans le haut, s'élargissent et s'approfondissent graduellement vers le bas, où ils forment enfin des ravines profondes, que l'on pourrait presque nommer des vallées. ces sillons ramifies sur toute la pente de la montagne et remplis encore de neige, tandis que leurs intervalles sont couverts de gazon, forment sur ce fond verd une broderie blanche, dont l'effet est extrêmement singulier. lorsque je passai là, le juillet , tous les enfoncemens de ces neiges étoient couverts de la poudre rouge que j'ai décrite § . «vers la bas de la descente, on trouve des chalets que je m'étonnai de voir construits en pierres de taille, d'une forme très régulière; je demandai la raison de cette recherche, peu commune dans les montagnes, et j'appris que c'étoit la nature qui avoit fait tous les frais de cette taille. effectivement je trouvai un peu plus bas une profonde ravine, creusée par les eaux dans des couches d'un beau grés qui se divise de lui-même, et que l'on voit dans sa position originelle actuellement divise en grands parallélépipèdes rectangles. est-ce une retraite opérée par le dessèchement, ou n'est-ce pas plutôt l'affaissement successif des couches qui les a divisées de cette manière? c'est ce que je ne déciderai pas dans ce cas particulier.» the only thing which, in this particular case, makes our author express his wonder, is the extreme regularity of these natural divisions of stone; for, the same appearances are to be found in every case of consolidated strata, though not always with such extreme regularity. but this is one of the most irrefragable arguments for those various bodies having been consolidated by means of heat and fusion. the contraction of the mass, consolidated by fusion or the effect of fire, is the cause of those natural divisions in the strata; and the regularity, which is always to be observed more or less, depends upon the proper circumstances of the case, and the uniform nature of the mass. (page .) «le matin avant de partir du chapiu, j'allai voir si les beaux grès rectangulaires, que j'avois observés la veille descendoient jusqu'au bas de la montagne; j'y trouvai effectivement des grès mais à couches minces, et qui ne se divisoient point avec régularité; en revanche, je vis des couches de ce grés ployées et reployées en zig-zags, comme celles que j'avois rencontrées aux contamines, § , et ces couches ondées étoient aussi renfermées entre de couches planes et parallèles. ce phénomène est bien plus rare dans les grès, que dans les roches feuilletées proprement dites.» thus every appearance is found by which the primitive _schisti_ are perfectly resembled, both as to their original formation and their accidents, with the strata, which are acknowledged by naturalists as being the common operation of the sea. our author then gives an account of the _passage de fours_, in which he makes the following observations: «§ . tout près du sommet du col, on rencontre de beaux bancs de grès jaunâtre qui sortent de dessous la pierre calcaire, et qui pourtant ne font aucune effervescence avec les acides. «§ . je mis deux heures et trois quarts à monter depuis le hameau du glacier jusqu'au haut du col, d'où l'on descend à la croix du bon-homme. j'envoyai mes mulets m'attendre à cette croix, et je m'acheminai avec pierre balme sur ma droite, pour atteindre le faite de la montagne dont la cime arrondie me paroissoit devoir dominer sur toutes les montagnes d'alentour. j'ai donné à cette sommité, qui n'avoit point de nom, celui de _cime des fours_, à cause du passage qu'elle domine. de grandes plaques de neige couvroient en divers endroits la route que j'avois à faire pour y aller; le roc se montroit cependant assez pour que l'on pût reconnoître sa nature. «§ . je traversai d'abord des couches des grès qui étoient la continuation de celles dont je viens de parler, § . je trouvai ensuite des bancs d'une espèce de poudingue grossier, dont le fond étoit ce même grès rempli de cailloux arrondis. quelques uns de ces bancs se sont décomposés, et les eaux out entraîné les parties de sable qui lioient les cailloux, en sorte que ceux-ci sont demeurés libres et entassés exactement comme au bord d'un lac ou d'une rivière. il étoit si étrange de marcher à cette hauteur sur des cailloux roulés, que pierre balme en témoigna son étonnement, même avant, que j'en parlasse. on auroit été tenté de croire qu'une cascade tombant anciennement de quelque rocher plus élevé, détruit dès-lors par le temps, avoit arrondi ces cailloux, si on n'en trouvoit pas de semblables encore enclavés dans les couches régulières du grès qui compose le haut de cette montagne. «§ . quoique depuis long-temps je ne doute plus que les eaux n'aient couvert et même formé ces montagnes, et qu'il y en ait même des preuves plus fortes que l'existence de ces cailloux roulés, cependant leur accumulation sur cette cime avoit quelque chose de si extraordinaire, et qui parloit aux sens un langage si persuasif, que je ne pouvois pas revenir de mon étonnement. si en marchant sur ces cailloux, et en les observant, j'oubliois pour un moment le lieu où j'étois, je me croyois au bord de notre lac; mais, pour peu que mes yeux s'écartassent à droite ou à gauche, je voyois au-dessous de moi des profondeurs immenses; et ce contraste avoit quelque chose qui tenoit d'un rêve; je me représentois alors avec une extrême vivacité les eaux remplissant toutes ces profondeurs, et venant battre et arrondir à mes pieds ces cailloux sur lesquels je marchois, tandis que les hautes aiguilles formoient seules des isles au-dessus de cette mer immense; je me demandois ensuite quand et comment ces eaux s'étoient retirées. mais il fallut m'arracher à ces grandes spéculations et employer plus utilement mon temps à l'exacte observation de ces singuliers phénomènes.» the fact here worthy of observation is the effect of time in decomposing this _grès_, or sand-stone, which contains the gravel. all the other appearances follow naturally from the situation of this place, which is a summit, and does not allow of such a collection of water as might travel or transport the loose gravel, although it has been sufficient for carrying away the sand. this decomposition of the sand stone we shall find also explained from what follows of the description of this place. «§ . tous les bancs de grès que l'on voit sur cette montagne ne renferment pas des cailloux roulés; il y a des alternatives irrégulières, de bancs de grés pur, et de bancs de grès mêlé de cailloux. les plus élevés n'en contiennent point. le plus haut de ceux qui en renferment est un banc bien suivi d'un pied d'épaisseur, et qui monte de degrés au nord-nord-ouest. «quelques-uns de ces bancs, remplis de cailloux, offrent une particularité bien remarquable; on voit à leur surface extérieure, exposée à l'air, une espèce de réseau formé par des veines noires solides, et saillantes de deux ou trois pouces au-dessus de la surface de la pierre; les mailles de ce réseau sont quelquefois irrégulieres, mais ce sont pour la plupart des quadrilatères obliquangles, dont les côtés ont huit à dix pouces de longueur. comme ces pierres ont toutes un tendance à se partager en rhomboïdes, il paroît qu'il y a eu anciennement des fentes qui divisoient les bancs en parties de cette forme; et que ces fentes ont été remplies par du sable qui a été cimenté par un suc ferrugineux; ce gluten solide a rendu ces parties plus dures que le reste de la pierre; et lorsque les injures de l'air ont rongé la surface de ces bancs, les mailles du réseau sont demeurées saillantes. «les cailloux arrondis, qui out été long-temps exposés à l'air, out aussi pris par dehors une teinte noirâtre ferrugineuse, mais ceux qui sont encore renfermés dans les bancs de grés ont comme lui une couleur jaunâtre. je n'en trouvai là aucun qui ne fut de nature primitive, et la plupart étoient de feldspath gris ou roux très-dur, et confusément crystallisé. ce sont donc des pierres qui n'ont point naturellement une forme arrondie; et qui, par conséquent, ne tiennent celle qu'elles ont ici, que du roulement, et du frottement des eaux. «tous ces grès font effervescence avec l'eau-forte, mais les parties du réseau ferrugineux en font beaucoup moins que le fond même du grès. de même si l'on compare entr'eux les grès qui renferment des cailloux avec ceux qui n'en contiennent pas, on trouve dans ceux-ci plus de gluten calcaire, l'eau-forte diminue beaucoup plus leur cohérence. «sur la cime même de la montagne, ces grès sont recouverts par une ardoise grise, luisante, qui s'exfolie à l'air. et si l'on redescend de cette même cime par le nord-est, du côté opposé au passage des fours, on retrouvera des bancs d'un grès parfaitement semblable, et qui se divisent là d'eux-mêmes en petits fragmens parallélépipèdes. «du haut de cette cime, élevée de toises au-dessus de la mer, on a une vue très entendue. au nord et au nord-ouest les vallées de mont joie, de passy, de sallanches; au couchant la haut cime calcaire dont j'ai parlé, § ; au sud les montagnes qui s'étendent depuis le chapiu jusqu'au col de la seigne; à l'est, ce même col que l'on domine beaucoup. sur la droite de ce col, on voit du côté de l'italie la chaîne du cramont, et plusieurs autres chaînes qui lui sont parallèles, tourner tous leurs escarpemens contre la chaîne centrale, de même qu'on voit du côte de la savoye, les chaînes du reposoir, de passy, de servoz, tourner en sens contraire leurs escarpemens contre cette même chaîne. car c'est-la une des vues très étendues sur les deux cotés opposés des alpes; puisque l'on découvre d'ici les montagnes de courmayeur et de l'allée blanche, qui sont du côté méridional de la chaine, et celles du faucigny et de la tarentaise, qui sont du côté septentrional. or les sites d'ou l'on jouit tout á-la-fois de ces deux aspects sont très rares; parce que les hautes cimes de la chaîne centrale sont presque toutes inaccessibles, et les cols par lesquels on la traverse sont presque tous tortueux, étroite, et ne présentent pour la plupart que de vues très bornées.» we have here two facts extremely important with regard to the present theory. the one of these respects the original formation of those alpine strata; the other the elevation of those strata from the bottom of the sea, and particularly the erection of those bodies, which had been formed horizontal, to their present state, which is that of being extremely inclined. it is to this last, that i would now particularly call the attention of my readers. it is rarely that such an observation as this is to be met with. perhaps it is rarely that this great fact occurs in nature, that is, so as to be a thing perceptible; it is still more rare that a person capable of making the observation has had the opportunity of perceiving it; and it is fortunate for the present theory, that our author, without prejudice or the bias of system, had been led, in the accuracy of a general examination, to make an observation which, i believe, will hardly correspond with any other theory but the present. if strata are to be erected from the horizontal towards the vertical position, a subterraneous power must be placed under those strata; and this operation must affect those consolidated bodies with a certain degree of regularity, which however, from many interfering circumstances, may be seldom the object of our observation. if indeed we are to confine this subterraneous operation to a little spot, the effect may be very distinctly perceived in one view; such are those strata elevated like the roof of a house, which m. de saussure has also described. but when the operation of this cause is to be extended to a great country, as that of the alps, it is not easy to comprehend, as it were, in one view, the various corresponding effects of the same cause, through a space of country so extensive, and where so many different and confounding observations must be made. in this case, we must generalize the particular observations, with regard to the inclinations of strata and their direction, in order to find a similar effect prevailing among bodies thus changed according to a certain rule; this rule then directs our understanding of the cause. the general direction of those alpine strata, in this place, is to run s.e. and n.w. that is to say, this is the horizontal line of those inclined beds. we also find that there is a middle line of inclination for those erected strata in this alpine region; as if this line had been the focus or centre of action and elevation, the strata on each side being elevated towards this lint, and declined from it by descending in the opposite direction. the view which our author has now given us from this mountain is a most interesting object, and it is a beautiful illustration of this theory; for, the breaking of the tops of mountains, composed of erected strata, must be on that side to which their strata rise; and this rupture being here towards the central line of greatest elevation, the ridges must in their breaking generally respect the central ridge. but this is the very view which our enlightened observator has taken of the subject; and it is confirmed in still extending our observations westward through the kingdom of france, where we find the ridges of the jura, and then those of burgundy gradually diminishing in their height as they recede from the centre of elevation, but still preserving a certain degree of regularity in the course of their direction. but our author has still further observed that this is a general rule with regard to mountains. i will give it in his own words, tom. . (p. .) «§ . mais la chaîne centrale n'est pas la seule primitive qu'il y ait de ce côté des alpes. du haut du cramont en se tournant du côté de i'italie, on voit un entassement de montagnes qui s'étendent aussi loin que peut aller la vue. parmi ces montagnes on en distingue un au sud-ouest qui est extrêmement élevée: son nom est _ruitor_: elle se présente au cramont à-peu-près près sous le même aspect que le mont-blanc à genève; sa cime est couverte de neiges, un grand glacier descend de sa moyenne région, et il en sort un torrent qui vient se jetter dans la riviere de la tuile. cette haut montagne, de nature primitive, est au centre d'une chaîne de montagnes moins élevées, mais primitives comme elle, et qui passent au-dessus du val de cogne. on voit de la cime du cramont des montagnes secondaires situées entre le cramont et cette chaîne primitive, et on reconnoît que les couches de ces montagnes s'élèvent contre cette chaîne en tournant le dos à la chaîne centrale. «§ . l'inclinaison du cramont et de la chaîne contre le mont-blanc, n'est donc pas un phénomène qui n'appartienne qu'à cette seule montagne; il est commun à toutes les montagnes primitives, dont c'est une loi générale que les secondaires qui les bordent, ont de part et d'autre leurs couches ascendantes vers elles. c'est sur le cramont, que je fis pour la première fois, cette observation alors nouvelle, que j'ai verifié ensuite sur un grand nombre d'autres montagnes, non pas seulement dans la chaîne des alpes, mais encore dans diverses autres chaînes, comme je le ferai voir dans le ive. volume. les preuves multipliées que j'en avois sous les yeux au moment où je l'eus faite, et d'autres analogues que ma mémoire me rappela d'abord, me firent soupçonner son universalité, et je la liai immédiatement aux observations que je venois de faire sur la structure du mont-blanc et de la chaîne primitive dont il fait partie. je voyois cette chaîne composée de feuillets que l'on pouvoit considérer comme des couches; je voyois ces couches verticales dans le centre de cette chaîne et celles des secondaires presque verticales dans le point de leur contact avec elles, le devenir moins à de plus grandes distances, et s'approcher peu-à-peu de la situation horizontale à mesure qu'elles s'éloignoient de leur point d'appui. je voyois ainsi les nuances entre les primitives et les secondaires, que j'avois déjà observées dans la matière dont elles sont composées, s'étendre aussi à la forme et à la situation de leurs couches; puisque les sommités secondaires que j'avois là sous les yeux se terminoient en lames piramidales aigues et tranchantes, tout comme le mont-blanc, et les montagnes primitives de la chaîne. je conclus de tout ces rapports, que, puisque les montagnes secondaires avoient été formées dans le sein des eaux, il falloit que les primitives eussent aussi la même origine. retraçant alors dans ma tête la suite des grandes révolutions qu'a subies notre globe, je vis la mer, couvrant jadis toute la surface du globe, former par des dépôts et des crystallisations successives, d'abord les montagnes primitives puis les secondaires; je vis ces matières s'arranger horizontalement par couches concentriques; et ensuite le feu ou d'autres fluides élastiques renfermes dans l'intérieur du globe, soulever et rompre cette écorce, et faire sortir ainsi la partie intérieure et primitive de cette même écorce, tandis que ses parties extérieures ou secondaires demeuroient appuyées contre les couches intérieures. je vis ensuite les eaux se précipiter dans les gouffres crevés et vides par l'explosion des fluides élastiques; et ces eaux, en courant à ces gouffres, entraîner à de grandes distances ces blocs énormes que nous trouvons épars dans nos plaines. je vis enfin après la retraite des eaux les germes des plantes et des animaux, fécondés par l'air nouvellement produit, commencer à se développer, et sur la terre abandonnée par les eaux, et dans les eaux mêmes, qui s'arrêtèrent dans les cavités de la surface. «telles font les pensées que ces observations nouvelles m'inspirèrent en . on verra dans le ive. volume comment douze ou treize ans d'observations et de réflections continuelles sur ce même sujet auront modifié ce premier germe de mes conjectures; je n'en parle ici qu'historiquement, et pour faire voir qu'elles sont les premières idées que le grande spectacle du cramont doit naturellement faire éclore dans une tête qui n'a encore épousé aucun système.» how far these appearances, which had suggested to this philosopher those ideas, agree with or confirm the present theory, which had been founded upon other observations, is here submitted to the learned. we have now not only found a cause corresponding to that which can alone be conceived as producing this evident deplacement of bodies formed horizontally at the bottom of the sea, but we have also found that this same cause has operated every where upon those strata, in consolidating by means of fusion the porous texture of their masses. now when the evidence of those two facts are united, we cannot refuse to admit, as a part of the general system of the earth, that which is every where to be observed, although not every where to such advantage as in those regular appearances, which our author has now described from those alpine regions. i have only one more example to give concerning this great region of the alps belonging to savoy and switzerland. it is from the author of les tableaux de la suisse. [ ] «on s'embarque à fluelen à une demi-lieue d'altorf sur le lac des quatre waldstoett ou cantons forestiers; les bords de ce lac sont des rochers souvent à pic et d'une très grande élévation et la profondeur de ses eaux proportionnée. ces roches sont toutes calcaires, et souvent remarquables par la position singulière de leurs couches. a une demi-lieue environ de fluelen, sur la droite, des couches de six pouces environ d'épaisseur sont déposées en zig-zags comme une tapisserie de point-d'hongrie; à une lieue et demie à côté de couches bien horizontales, de quatre à cinq pieds d'épaisseur il y en a de contournées de forme circulaire et d'elliptiques. il seroit difficile de se faire une idée de la formation de pareilles couches, et d'expliquer comment les eaux ont pu les deposer ainsi.» [footnote : discours sur l'hist. nat. de la suisse, page clv.] having thus given a view of a large tract of country where the strata are indurated or consolidated and extremely elevated, without the least appearance of subterraneous fire or volcanic productions, it will now be proper to compare with this another tract of country, where the strata, though not erected to that extreme degree, have nevertheless been evidently elevated, and, which is principally to the present purpose, are superincumbent upon immense beds of basaltes or subterranean lava. this mineral view is now to be taken from m. de luc, lettres _phisiques_ et morales, tom. . this naturalist had discovered along the side of the rhine many ancient volcanos which have been long extinct; but that is no part of the subject which we now inquire after; we want to see the operations of subterraneous lava which this author has actually exposed to our view without having seen it in that light himself. he would persuade us, as he has done himself, that there had been in the ancient sea volcanic eruptions under water which formed basaltic rocks; and that those eruptions had been afterwards covered with strata formed by the deposits made in that sea; which strata are now found in the natural position in which they had been formed, the sea having retreated into the bowels of the earth, and left those calcareous and arenaceous strata, with the volcanic productions upon which they had been deposited, in the atmosphere. it would be out of place here to examine the explanation which this author has given with regard to the consolidation of those deposited strata which is by means of the filtration of water, but as in this place there occurs some unusual or curious examples of a particular consolidation of limestone or calcareous deposits, as well as similar consolidations of the siliceous sort, it may be worth while to mention them in their place that so we may see the connection of those things, and give all the means of information which the extremely attentive observations of this naturalist has furnished to the world of letters. at oberwinter our author remarks a stratum of consolidated sand above volcanic matter, tome , p. . «tant que j'ai parcouru le pied du cône, je n'ai vu qu'un terrain composé de ces débris, et cultivé en vignes. mais après l'avoir dépassé, j'ai trouvé la coupe verticale d'une colline à couches pierreuses, si réguliers, que je les ai prises au premier coup d'oeil pour de la pierre à chaux. l'esprit de nitre m'a détrompé: c'est une pierre sableuse très compacte, dont les couches, qui n'ont souvent que quelques pouces d'épaisseur, s'élèvent par une pente insensible vers le cône volcanique qu'elle recouvrent de ce coté là sans aucune apparence de désordre. ces couches qui sont visiblement des dépôts de la mer, quoique je n'y ai pas trouvé de corps marins, ont été formées depuis que le cône s'étoit élevé.» this is a species of reasoning which this acute naturalist would surely not have let pass in any other cosmologist. but here the love of system, or a particular theory, seems to have warped his judgment. for, had our author been treating of beds or bodies deposited in water, and preserving the natural situation in which they had been formed, he would have had reason to conclude that the superior bed was of the latest formation; but here is no question of superincumbent strata; it is a stratum which is superincumbent on a lava; and it is equally natural to suppose the lava posterior to the stratum as the stratum posterior to the lava. our author meets with a limestone too much erected in its position to be supposed as in its natural place, and then he explains this phenomenon in the following manner, p. . «les rochers d'ehrentbreitstein et de lahnstein sont donc des faits particuliers. ces rochers là ont été formes par des dépôts de la mer: les corps marin qu'ils renferment en font foi. dès lors ils ont dû avoir dans leur origine la seule position que la mer pût leur donner; l'horizontale ou légèrement inclinée. leur couches sont aujourd'hui rompues, et leur inclination n'est plus celle de dépôts immédiats de la mer. les collines, auxquelles elle appartenoient, sont en même tems entourées de volcans anciens; et il est naturel d'en conclure, que c'est à eux que ces grands rochers doivent leur position actuelle.» here one would expect our author is to allow that volcanos may erect rocks in heightening them in their place; but this is not the light in which it has been seen by him, as will appear from what follows. «l'enfoncement d'une de leurs cotés n'est rien, quand on considère le prodigieuse excavation qui ont dû se faire, pour porter au dehors toutes les montagnes, les collines, et les plaines volcaniques qui se trouvent dans ce vaste circuit.» when a small portion of a stratum is examined, such as the present case, it is impossible from inspection to determine, whether it owes its inclined position to the sinking or the raising of the ground; the stratum is changed from its original position, but whether this has been brought about by the raising of the one side, or the sinking of the other is not apparent from what then is seen. but unless we are to explain the appearance of strata above the level of the sea by a supposition which is that of the retreat of the ocean, a theory which this author has adopted, it is as impossible to explain the present appearance of horizontal strata as of those that are inclined. at the same time, if a power placed below the strata is to be employed for the purpose of raising them from the bottom of the sea, to the place in which we find them at present, it is impossible that this should be done without the fracture of those strata in certain places; and it is much more difficult to conceive this operation not to be attended with changing the natural horizontal position of strata, and thus leaving them in many places inclined, than otherwise by supposing that this internal power of the globe should elevate the strata without changing their original position. with this description of strata on the rhine, we may compare that of m. monnet respecting those which he found upon the meuse, (nouveau voyage minéralogique, etc. journal physique, aoust, .) speaking of the schistus, or slate, he adds: «mais ces petites veines nous donnent lieu de faire une observation importante; c'est qu'elles se présentent assez communement perpendiculaire, tandis que les grands bancs d'ardoises, ceux qu'on exploite, sont, comme nous l'avons dit, couchés sur une ligne de à degrés. j'ai parlé des montagnes de marbre qui sont derrière givet, et de celles sur la quelle est situé charlemont. j'ai fait voir que bien loin que les bancs de marbre, qui forment la montagne du givet, soient horizontaux comme on seroit tenté de le croire, d'après les principes de quelques naturalistes systématiques, qui pensent que tous les bancs de pierres calcaires ne sauroient être autrement; j'ai fait voir, dis-je, que ces bancs sont presque perpendiculaire à l'horizon; et de plus, qu'ils sont tellement collés les uns contre les autres, qu'à peine on peut les distinguer.» the changed structure and position of the strata, now exemplified from the observations both of m. de saussure and m. de luc, observations made in a great extent from france to germany, show the effects without the means by which those effects had been produced; and, in this case, it is by judging from certain principles of natural philosophy that the cause is discovered in the effect. we are now to see the deplacement of at least a great body of earth in another light, by having at the same time in our view both the cause and the effect. nothing can give a more proper example of this than the mine of rammelsberg; and no description better adapted to give a clear idea than that of m. de luc, which i shall now transcribe. lettres phisiques et morales, tome . p. to . «deux _filons_ principaux occupent les mineurs dans le _rammelsberg_: filons immenses, car ils ont jusqu'à ou toises d'épaisseur dans une étendue dont on ne connoit pas encore les bornes. l'un de ces _filons_ fait avec l'horizon un angle de degrés; c'est l'inférieur: l'autre s'élève de degrés: et leur distance étant peu considérable, leurs plans doivent se rencontrer dans un point qui n'est pas fort éloigné des mines. leurs _directions_ sont aussi différentes: celle du _filon_ de degrés est à ½ _heures_; et celle du _filon_ de degrés est a _h._- / : tellement qu'ils se croisent à l'endroit ou est percé le puits des pompes. «on est embarrassé d'expliquer l'état de cette montagne par des secousses. il faut au moins supposer que la montagne entière a été culbutée, et encore reste-t-il à comprendre, comment s'est soutenue cette grande piece qui sépare les filons, et qui, en supposant vuides les espaces de ceux-ci, se trouveroit absolument en l'air. «ce phénomène important à l'histoire des montagnes, je veux dire ces intersections des _filons_, est très fréquent dans les mines et très remarqué par les mineurs. il arrive souvent que des _filons_, qui sont à la même _heure_, c'est-à-dire, qui ont des _directions_ semblables vers l'horizon, ont une chute ou inclinaison différente, et telle que leurs deux plans se coupent à une certaine profondeur. si le mineur ne s'en apperçoit pas assez tôt, et que des le commencement de son exploitation, il n'étançonne pas fortement partout ou il enlevé les _filons_, tout son ouvrage peut être écrasé par l'enfoncement de la pièce qui les séparoit. cette pièce même a un nom chez le mineurs; ils la nomment _bergkiel_, c'est-à-dire coin de la matière de la montagne: et quand deux filons sont voisins l'une de l'autre, le géomètre souterrain en étudie l'inclinaison pour juger à l'avance s'il y aura un _bergkiel_; et qu'en ce cas la mineur prenne ses précautions, en conservant des appuis naturels dans la gangue, ou s'en faisant d'artificiels, à mesure qu'il s'enfonce. or si, en élevant les filons, ce coin se trouve sans appui; comment s'est-il soutenu avant que les filons fussent formés? «voilà une question forte embarrassante. mais peut-être n'a-t-on pas fait assez d'attention jusqu'ici à la mauvaise gangue, qui se trouve être de la même nature que la montagne. peut-être trouveroit on par la, qu'en même tems que les fentes se font faites, il y est tombé des pièces des còtés, qui ont empêché la réunion des parties de la montagne; fragmens qui, aujourd'hui, font partie des _filons_, et qu'on pourroit laisser encore pour appuis naturels, n'exploitant qu'autour d'eux lorsqu'on auroit appris à les connoître. «ce peu d'inclinaison des _filons_ du rammelsberg rappelleroit l'idée des _couches_ formées de dépôts successifs, s'ils étoient parallèles. mais leur manque de parallélisme en tout sens exclut cette explication. car dans toutes les montagnes qui doivent leur formation aux dépôts des eaux, les _couches_ sont parallèles; et l'on sent bien qu'elles doivent l'être. «la nature des _filons_ du _rammelsberg_ est aussi différente de celle de _claustbat_ que l'est leur situation. c'est un massif compacte, et presque partout le même, de minéral de _plomb_ et _argent_ pauvre, pénétré de _pyrite_ sulphureuse. ils sont traversés en plusieurs endroits par de _ruscheln_, qui ont fait glisser le toit vers le _mur_; tellement que malgré l'épaisseur de ces _filons_, on crut une fois en avoir trouvé la fin. ils sont aussi coupés dans leur intérieur, en sens différens, par d'autres plus petits _filons_, composés de matières très différentes; surtout d'une _pyrite cuivreuse_ dure et pauvre, et que par cette raison on ne tente pas de séparer. «en mettant à part ces petits _filons_ particuliers, ainsi que les ruscheln, dus probablement les uns et les autres à des causes postérieures à celles qui ont produit les filons principaux, la masse compacte de ceux-ci réveille beaucoup l'idée d'une matière fondue; en même tems qu'on seroit fort embarrassé à concevoir, d'où viendroit cette matière, si distincte de toute autre, lorsqu'on voudroit l'attribuer à l'eau. «cette idée, que je dois à mr. de redden, perfectionnée par l'étude des phénomènes, donnera peut-être un jour le mot de toutes ces énigmes.» here is the clearest evidence that an enormous mass of mountain had been raised by a subterranean force; that this force had acted upon an enormous column of melted minerals, the specific gravity of which is great; and that this fluid mass had suspended a great wedge of this mountain, or raised it up. now, if by means which are natural to the globe, means which are general to the earth, as appearing in every mineral vein, this mass of mountain had been raised up and suspended twenty fathoms, there is no reason why we should suppose nature limited, whether in raising a greater mass of earth, or of raising it a greater height. that the height to which the land of this globe shall be raised, is a thing limited in the system of this earth, in having a certain bounds which it shall not exceed, cannot be disputed, while wisdom in that system is acknowledged; but it is equally evident, that we cannot set any other bounds to the operation of this cause, than those which nature appears actually to have observed in elevating a continent of land above the level of the sea for the necessary purpose of this world, in which there is to be produced a variety of climates, as there is of plants, from the burning coast under the equator to the frozen mountains of the andes. here therefore we have, although upon a smaller scale, the most perfect view of that cause which has every where been exerted in the greater operations of this earth, and has transformed the bottom of the sea to the summits of our mountains. now, this moving power appears to have been the effect of an internal fire, a power which has been universally employed for the consolidation of strata, by introducing various degrees of fusion among the matter of those masses, and a power which is peculiarly adapted to that essential purpose in the system of this earth, when dry land is formed by the elevation of what before had existed as the bottom of the sea. i hope it will not be thought that too much is here adduced in confirmation of this part of the theory. the elevation of strata from their original position, which was horizontal, is a material part; it is a fact which is to be verified, not by some few observations, or appearances here and there discovered in seeking what is singular or rare, but by a concurrence of many observations, by what is general upon the surface of the globe. it is therefore highly interesting not only to bring together that multitude of those proofs which are to be found in every country, but also to give examples of that variety of ways in which the fact is to be proved. were it necessary, much more might be given, having many examples in this country of scotland, in derbyshire, and in wales, from my proper observation; but, in giving examples for the confirmation of this theory, i thought it better to seek for such as could not be suspected of partiality in the observation. chap. iii. _facts in confirmation of the theory, respecting those operations which re-dissolve the surface of the earth_. we have now discussed the proof of those mineral operations by which the horizontal strata, consolidated at the bottom of the sea, had been changed in their position, and raised into the place of land. the next object of our research is to see those operations, belonging to the surface of the earth, by which the consolidated and erected strata have been again dissolved, in order to serve the purpose of this world, and to descend again into the bottom of the sea from whence they came. of all the natural objects of this world, the surface of the earth is that with which we are best acquainted, and most interested. it is here that man has the disposal of nature so much at his will; but here, man, in disposing of things at the pleasure of his will, must learn, by studying nature, what will most conduce to the success of his design, or to the happy economy of his life. no part of this great object is indifferent to man; even on the summits of mountains, too high for the sustaining of vegetable life, he sees a purpose of nature in the accumulated snow and in majestic streams of the descending ice. on every other spot of the surface of this earth, the system of animal and vegetable life is served, in the continual productions of nature, and in the repeated multiplication of living beings which propagate their species. but, for this great purpose of the world, the solid structure of this earth must be sacrificed; for, the fertility of our soil depends upon the loose and incoherent state of its materials; and, that state of our fertile soil necessarily exposes it to the ravages of the rain upon the inclined surface of the earth. in studying this part of the economy of nature, we may perceive the most perfect wisdom in the actual constitution of things; for, while it is so ordered that the solid mass of earth should be resolved for the purpose of vegetation, the perishable soil is as much as possible preserved by the protection of those solid parts; and these consolidated masses are resolved in so slow a manner, that nothing but the most philosophic eye, by reasoning upon a chain of facts, is able to discover it. thus it may be concluded, that the apparent permanency of this earth is not real or absolute; and that the fertility of its surface, like the healthy state of animal bodies, must have its period, and be succeeded by another. the study of this subject must tend to enlarge the mind of man, in seeing what is past, and in foreseeing what must come to pass in time; and here is a subject in which we find an extensive field for investigation, and for pleasant satisfaction. the hideous mountains and precipitous rocks, which are so apt to inspire horror and discontentment in minds which look at sensible objects only for immediate pleasure, afford matter of the most instructive speculation to the philosopher, who studies the wisdom of nature through the medium of things. as, on the one hand, the summit of the mountain may be supposed the point of absolute sterility, so, on the other, the sandy desert, moved by nothing but the parching winds of continents distant from the sources of abundant rains, finishes the scale of natural fertility, which thus diminishes in the two opposite extremes of hot and dry, of cold and wet; thus is provided an indefinite variety of soils and climates for that diversity of living organised bodies with which the world is provided for the use of man. but, between those two extremes, of mountains covered with perpetual snow, and parched plains in which every living thing must perish, we find the most pleasant subject of contemplation, in studying the means employed in nature for producing the beautiful and benevolent system of hills and valleys, of fertile soils and well watered plains, of the most agreeable circumstances and proper situations for every thing that lives, and for the preservation of an indefinite variety of organised bodies which propagate their species. without this philosophic view of things, the prospect of the surface of this earth is far from giving always satisfaction or contentment to the mind of man, who is subject to be continually displeased with that which is presented to his view, and which, in his opinion, is not the best; in his partial views of things, it is either too high or too low, too cold or too warm, too moist or too dry, too stiff for the labour of his plough, or too loose for the growing of his corn. but, considering nature as the common parent of living growing propagating bodies, which require an indefinite variety of soils and climates, the philosopher finds the most benevolent purpose in the end proposed, or effect which is attained, and sees perfect wisdom in the effectual means which are employed. this is the view that i would wish men of science to take; and it is for this purpose that i am now to examine the phenomena of the surface of this earth. if strata, formed at the bottom of the sea, had been consolidated by internal operations proper to the earth, and afterwards raised for the purpose of a habitable world; and if, for the purpose of vegetation, the solid land must be resolved into soil by the dissolution and separation of its parts, as is required in the theory, the strata, instead of being entire immediately below the soil, should be found in a mutilated state; the ends of hard and solid beds should present their fractures or abrupt sections immediately under the confused materials with which they are covered; and the softer strata should appear to suffer gradual resolution and decay, by which may be perceived their transition into soil, the most important part of all the operations of the globe which do not immediately concern our life. these are facts which every person of observation has it in his power to verify; they are facts for which nothing further can be laid than that the thing is truly so; and they are facts from which the most important arguments might be formed, were any doubt to be entertained concerning the justness of the theory which has now been given. the theory consists in this, that it is necessary to have a habitable country situated in the atmosphere, or above the surface of the sea. it is difficult to say precisely what constitutes a habitable country. a resting place out of the water suffices for such amphibious animals as, while they necessarily live in the atmosphere, feed in the sea. man, more versatile in his nature than most animals, and more capable of adapting his manners to his circumstances, is even sometimes found subsisting in situations where the land affords him little more than it does the seal on which he feeds. the growth of terrestrial plants, however, seems necessary to the idea of a habitable country; and, for the growth of plants, there is required soil: now, this is only to be procured by the resolution or decay of solid land. we are not to consider the resolution of our land as being the effect of accident, while it is performed by the operations of the sun and atmosphere, by the alternate action of moisture and of drought, and by the casual operations of a river in a flood. nothing is more steady than the resolution of our land; nothing rests upon more certain principles; and there is nothing which in science may be more easily investigated. calcareous, argillaceous, and other soluble earths, compose many of the strata; but in many more, which are partly or chiefly composed of insoluble substances, those soluble earths are mixed in various proportions. now, when the siliceous substance, which is the insoluble part, shall be supposed resisting every effort of the elements towards its dissolution, those compound masses upon the surface of the earth, however endued with hardness and solidity, are gradually impaired by the dissolution of some of their constituent parts, and by the separation of others which are thus exposed to the ablution of water. in like manner, by the resolution of the surrounding parts, the solid _silex_, which is supposed to be insoluble, is removed from its bed, and thus suffers new parts of the solid land to be exposed to those injuries of the air, by which the general good of plants, of animals, and even of future worlds, are consulted. the solid land is resolved into stones, gravel, sand, earths, and clays; all or either of these, by retaining moisture, and affording places for the roots of plants, are disposed for vegetation in different degrees; a mixture of the different earths being, upon the whole, the best suited to that purpose; and this compound body, mixed with vegetable or animal substances, becoming a most luxuriant soil. soils are thus formed, either by the resolution of the surface of that land upon which they are to rest, or by the transportation of those solid parts to be again deposited upon another basis. in this manner soils are constantly changing upon the same spot; sometimes they are meliorated, at other times impoverished. from the tops of the mountains to the shores of the sea, all the soils are subject to be moved from their places, by the natural operations of the surface, and to be deposited in a lower situation; thus gradually proceeding from the mountain to the river, and from the river, step by step, into the sea. countries are thus formed at the mouths of rivers in the sea, so long as the quantities of materials transported from the land exceeds that which is carried from the shore, by tides and currents, into the deeper water. the soil, with which the surface of this earth is always covered more or less, is extremely various, both with respect to quantity and quality; it is found resting upon the solid parts; and those solid parts are always more or less affected by the influences of the atmosphere near the surface of the earth. those parts of the strata which approach the surface are always in a decayed state; and this sometimes may be observed for very considerable depths, according as the quality of the materials, and the situation of the place dispose to that effect. this general observation however may be formed, that, _cet. par._ the strata become always more solid, or are found in their sound and natural state, more and more in proportion as we sink into the earth, or have proceeded from the surface. there is nothing of which we have more distinct experience than this, that, universally upon the surface of the earth, the solid parts are dissolving and always going into decay; whereas, at a sufficient depth below, they are found in their natural consolidated state. the operations of man in digging into the ground, as well as the sections of the earth so often formed by brooks and rivers, affords such ample testimony of this truth that nothing farther need be observed upon this head only that this is a most important operation in the natural economy of the globe, and forms a subject of the greatest consequence in the present theory of the earth, which holds for principle, that the strata are consolidated in the mineral regions far beyond reach of human observation. consistently with this view of things, the strata or regular solid parts, under the soil or travelled earth, should be found in some shape corresponding to the represented state of those things, when affected by the powers which have acted upon the surface of the earth. here, accordingly, the strata are always to be observed with those marks of resolution, of fracture, and of separation, which have most evidently arisen from the joint operation of those several causes that have been now explained. but though every operation of the globe be necessarily required for the explanation of those appearances which we now examine, it is principally the action of the sun and atmosphere, and the operations of the waters flooding the surface of the earth, that form the proper subject of the present investigation. it must not be imagined that, from the present state of things, we may be always able to explain every particular appearance of this kind which occurs; for example, why upon an eminence, or the summit of a ridge of land which declines on every side, an enormous mass of travelled soil appears; or why in other places, where the immediate cause is equally unseen, the solid strata should be exposed almost naked to our view. we know the agents which nature has employed for those purposes; we know the operations in which the solid parts are rendered soil of various qualities and for different purposes; and when we find the marks of those natural operations in places where, according to the present circumstances, the proper agents could not have acted or existed, we are hereby constrained to believe, that the circumstances of those places have been changed, while the operations of nature are the same. it is thus that we shall find reason to conclude an immense period of time, in those operations which are measured by the depradations of water acting upon the surface of the earth; a period however which is to be esteemed a little thing compared with that in which a continent had taken birth and gone into decay; but a period which interests us the more to examine, in that it approaches nearer to another period, for the estimation of which _some data_ may perhaps be found by naturalists and antiquaries, when their researches shall be turned to this subject. it is only in this manner that there is any reasonable prospect of forming some sort of calculation concerning that elapsed time in which the present earth was formed, a thing which from our present data we have considered as indefinite. in this view which we are now taking of the surface of the earth, nothing is more interesting than the beds of rivers; these take winding courses around the hills which they cannot surmount; sometimes again they break through the barrier of rocks opposed to their current; thus making gaps in places by wearing away the solid rock over which they formerly had run upon a higher level; and thus leaving traces of their currents in the furrowed sides of rocky mountains, far from the course of any water at the present time. so strongly has m. de saussure been impressed with this and some other appearances, that he has imagined a current of water which, however in the possibility of things, is not in nature; and which moreover could not have produced the appearances now mentioned, which is the work of time, and the continued operation of a lesser cause. we are further obliged to him for the following facts. vol. . (page .) «les tranches nues et escarpées des grandes couches du petit et surtout du grande saleve, présentent presque partout les traces les plus marquées du passage des eaux, qui les ont rongées et excavées, on voit sur ces rochers, des sillons à peu près horizontaux, plus ou moins larges et profonds; il a de à pieds de largeur, et d'une longueur double ou triple, sur ou pieds de profondeur. tous ces sillons ont leur bords terminés des courbures arrondies; telles que les eaux ont coutume de les tracer. je dis qu'ils sont à peu près horizontaux, parce qu'ils sont par fois inclinés de quelques degrés, en descendant vers le sud-sud-ouest, suivant la pente qu'a du avoir le courant.» this is evidently the effect of a river running along the side of a rock of such soft materials as may be worn by the friction of sand and stones; and such are the materials of the rocks now considered. notwithstanding that it is so easy to explain this appearance by the operation of natural causes, m. de saussure proceeds in taking it in another view. «de tels filons ne sauroient avoir été tracés par les eaux des pluies; car celles-ci forment des excavations, ou perpendiculaires à l'horizon ou dirigées suivant la plus grande inclinaison des faces des rochers; au lieu que celles la font tracées presqu'horizontalement sur de faces tou-à-fait verticales.» here our author takes it for granted that things upon the surface of this earth were always the same as at present; and he reasons justly from these principles. but we are now tracing a former state of things; and those furrowed rocks testify the former current of a river by their side. this operation of rivers undermining the sides of mountains, and causing scenes of ruin and destruction, may be illustrated by what our author has described under the title of _ravage du temps sur les rochers de saleve_, § . «là ou ces couches manquent, il est aisé de voir qu'elles ont été détruites par le tems; les couches même horizontales, contres lesquelles elles out appuyées, ont souffert en bien des endroits des altérations considérables. «un peintre qui voudroit monter son imagination, et se faire des grandes idées des ravages du tems sur de grands objects, devroit aller au pied de saleve, à l'extrémité des ces grands rochers, au-dessus du coin, hameau fort élevé de la paroisse de collonge. «on voit là des rochers taillés à pic à la hauteur de plusieurs centaines de pied avec des faces, ici planes et uniformes, là partagées et sillonnes par les eaux. «la base de ces rochers est couverte de débris et de fragmens énormes, confusément entassés; un de ces débris soutenu fortuitement par d'autres est demeuré, et paroît de près un obélisque quadrangulaire d'une hauteur prodigieuse; de plus loin on reconnoît que sa sommité est une arrête tranchante, et qu'il a la forme d'un coin; et c'est peut-être cette forme qui a donné son nom au hameau qu'il domine. «l'angle même de la montagne est partagé par une fente qui le traverse de part en part. cette profonde fissure mérite qu'on la voye, et même qu'on la pénètre. elle est tortueuse, et dans quelques endroits si étroite, qu'à peine un homme peut il y passer. quand vous y êtes engagés vous trouvez des places ou les sinuosités du rocher vous cache le ciel, plus loin elles le laissent apercevoir par échappées; ailleurs vous voyez des blocs de rochers engagés dans la crevasse, et suspendus au-dessus de votre tête.» in his route from contamine to bonneville, he observes, page , «enfin vis-a-vis la bonne-ville, ces mêmes escarpemens des bases du mole, présentent une grande échancrure, qui paroît être le vuide qu'a laissé une montagne qui s'est anciennement écroulée; ses débris sont encore entassés au-dessous de l'échancrure. il paroît même qu'elle étoit plus élevée que ses voisines, j'en juge par leur couches qui montent à droite et à gauche, contre le vuide qu'elle à laissé. «§ . en suivant la route de servez, on voit sur sa gauche la continuation des rocs escarpés qui couronnent les montagnes situées au-dessus de passy. un de ces rochers est si élevé, et en même tems si mince que l'on a peine à concevoir qu'il puisse se tenir debout et résister aux orages. «c'est auprès de cette sommité élevée qu'étoit située une montagne qui s'éboula en , avec un fracas si épouvantable, et une poussière si épaisse et si obscure, que bien de gens crurent que c'étoit la fin du monde.» vitaliano donati, who was sent from turin to examine this phenomenon, says in his letter, which m. de saussure transcribes, that the great snows, which fell that year in savoy, increasing the operation of some lakes, the waters of which continually undermined this mountain, occasioned the fall of three millions of cubic toises of rock. in describing the saleve, our author proceeds to mention other appearances equally conclusive with regard to the operations of water, but such as may be found over all the surface of the globe, to have been brought about by natural causes. «ce que l'on nomme le grottes de l'hermitage, ou ces excavations profondes de pieds, et ou fois aussi longues produites par la destruction totale de plusieurs couches de rocher. «la gorge même de monetier, ou cette grande échancrure qui sépare le grand saleve du petit, et dans le fond de laquelle est renfermé le joli vallon de monetier, paroît avoir été formée par un courant semblable, qui descendant des alpes par la vallée de l'arve, venoit se jetter dans notre grand courant; car les couches correspondantes du grand et du petit saleve indiquent leur ancienne jonction; et l'on ne comprend pas quel agent auroit pu détacher et emporter la pièce énorme qui manque en cet endroit à la montagne.» further, in treating of the changes made in the form of the jura by the ravages of time, our author observes, page , vol. i. «le faite de la montagne, battu de tous cotés par les vents, et par les pluies, a souffert des altérations les plus grandes: ici les couches du coté du lac ont été detruites, et laissent voir les sommités des couches opposées, dont les escarpemens paroissent tourner contre ce même lac; là, ce font les couches du coté de la vallée de mijoux, qui out été emportées, et la montagne en pente uniforme de notre coté, est escarpée du coté de celle vallée; plus loin, le faite entier a été enlevé, et là on voit des abaissemens ou des gorges comme aux faucilles, à st. serge, etc. «les flancs et la base de la montagne ont aussi été dégradés par les torrens que produisent la pluie et les neiges fondues, qui ont formé de larges et profondes excavations.» these ravages of time, or rather of the wasting operations of the surface of the earth, however great, compared with the little changes that we find in our experience, or in the most ancient record of our histories, are little things, considering the softness and solubility of the materials, and compared with the wasting of the alps, which we find in tracing up those same rivers to their sources in the icy valleys. let us go up the arve to the valley of chamouni. from this fertile valley, m. de saussure heads us up the montanvert, fathoms above the level of the valley, and consequently above that of the sea. from this mountain we descend again into the high frozen valley which runs between the granite mountains, and pours its ice into the valley of chamouni. in this high valley, which communicates with an immensity of the like kind, we find ourselves among the most hard and durable materials. here we must perceive, that most enormous masses of those solid materials had, in the course of time, been wasted by the flow effects of air and water, of the sun and frost, in order to hollow out those barren valleys of immense extent, which have, during an amazing tract of time, contributed from their solid rocks to the formation of travelled soils below, but which materials have long ago been travelling in the sea. the sides of those valleys are solid rock here exposed naked to our view. it is to such a place as this that we should go to see the operations of the surface wasting the solid body of the globe, and to read the unmeasurable course of time that must have flowed during those amazing operations which the vulgar do not see, and which the learned seem to see without wonder! m. de saussure, in his second volume of _voyages dans les alps_, has given us a most interesting view of this scene, p. . «en montant au montanvert, on a toujours sous ses pieds la vue de la vallée de chamouni, de l'arve qui l'arrose dans toute la longueur, d'une soule de villages et de hameaux entourés d'arbres et de champs bien cultivés. au moment ou l'on arrive au montanvert, la scène change; et au lieu de cette riante et fertile vallée, on se trouve presqu'au bord d'un précipice, dont le fond est une vallée beaucoup plus large et plus étendue, remplie de neige et de glace, et bordée de montagnes colossales, qui étonnent par leur hauteur et par leurs formes, et qui effraient par leur stérilité et leurs escarpements.» it is the cause of this appearance, of deep valleys and colossal mountains, that i would now wish my readers to perceive. this is a thought which seldom strikes the mind of wondering spectators, viewing those lofty objects; they are occupied with what they see, and do not think how little what they see may have been, compared with what had been removed in the gradual operations of the globe. we have but to suppose this scene hewn out of the solid mass of country raised above the level of the valley; and, that this had been the case, must appear from the examination of all around. let us follow our author up those valleys between the solid granite mountains, valleys which properly are great rivers of ice moving, grandly but slowly, the ruins of those mountains upon which they were gathered. it is the glacier de bois upon which he is set out, (p. .) «après une bonne demi-heure de marche sur le glacier, nous traversons une arrête de glace chargée de terre, de sable et de débris de rocher. j'ai parlé dans le er. vol. de ces arrêtes parallèles à la longueur de glaciers, que l'on voit souvent dans le milieu de leur largeur, ou à des distances plus ou moins grandes de leurs bords. j'ai fait voir qu'elles sont produites par des débris qui du haut des montagnes, roulent sur le glacier, et qui entraînés par la glace sur laquelle ils reposent suivent comme elle une direction oblique en descendant tout-à-la-fois vers le milieu et vers le bas de la vallée. «dix minutes après, nous traversâmes une seconde arrête plus haute que la premiere, et nous jugeâmes que sous ces débris la glace étoit de ou pieds plus élevée que dans les endroits où l'air et les rayons du soleil agissent librement sur elle. on rencontre une troisième arrête à vingt minutes de la seconde, et la quatrième, qui est la dernière, la suit de très-près. «ici nous nous trouvons au point où le glacier des bois se divise, comme je l'ai dit, § , en deux grandes branches, dont l'une tourne à droite vers le mont-blanc, et prend le nom de glacier de _tacul_, et l'autre à gauche se nomme le glacier de _lechaud_. il seroit, sans doute, plus intéressant de suivre celle de la droite, et de s'approcher ainsi du mont-blanc; ses pentes de neige et de glace, qui se presentent à nous, semblent même n'être point absolument inaccessibles: mais ce sont des apparences trompeuses; des glaciers entrecoupés de profondes crevasses masquées çà et là par des couches minces de neige les approches de cette redoutable montagne, quoique peut-être en choisissant une année ou il seroit tombé beaucoup de neige, et en prenant le temps où cette neige seroit encore ferme, quelque chasseur adroit et courageux pourroit tenter cette route. «comme dans ce moment cette entreprise est absolument impraticable, nous suivons la branche gauche de la vallée, et après deux heures de marche sur le glacier des bois, nous en sortons au pied de celui du taléfre, c'est-à-dire, à l'endroit où celui-ci vient verser sa glace dans celui-là qui a changé de nom, et qui s'appelle ici le _glacier de léchaud_. «la vue du glacier du taléfre est ici majestueuse et terrible. comme la pente par laquelle il descend est extrêmement rapide, les glaçons se pressant mutuellement, se dressent, se relèvent, et présentent des tours, des pyramides diversement inclinées, qui semblent prêtes à écraser le voyageur téméraire qui oseroit s'en approcher. «pour parvenir au sommet de ce glacier, où il est moins incliné et par cela même moins inégal, nous gravissons le rocher qui est à la gauche du côté du couchant. ce rocher se nomme _le couvercle_; il est dominé par une cime inaccessible, qui, suivant l'usage du pays, est décorée du nom _aiguille_, et, en prenant le nom du glacier le plus proche, s'appelle _l'aiguille du taléfre_. «la pente, par laquelle on gravit le couvercle, est excessivement rapide; on suit une espèce de sillon creusé dans le roc par la nature; quelques pointes de roc aux quelles on se cramponne, en montant avec les mains, autant et plus qu'avec les pieds, ont fait donner à ce passage le nom _d'égralets_ ou de petits degrés. ce passage n'est cependant point dangereux, parce que le roc, qui est un granit très-cohérent, permet d'assurer toujours solidement les mains et les pieds; mais la rapidité le rend un peu effrayant à la descente. «lorsqu'on est au haut des égralets, on suite un pente beaucoup moins rapide; on marche tantôt sur du gazon, tantôt sur de grandes tables de granit, et on arrive ainsi au bord du plan du glacier du taléfre. on nomme le _plan_ d'un glacier la partie élevée et à-peu-près horizontale dans laquelle on peut le traverser. «nous avions mis une heure et un quart à monter du glacier de léchaud au plan de celui du taléfre. nous fumes tentés de nous reposer un moment avant d'entrer sur celui-ci. tout nous invitoit à choisir cette place, un beau gazon arrosé par un ruisseau qui sortoit de dessous la neige et qui rouloit son eau crystalline sur un sable argenté, et ce qui étoit plus séduisant encore, une vue d'une étendue et d'une beauté dont une description ne peut donner qu'une bien foible idée. «§ . en effet comment peindre, à l'imagination des objets qui n'ont rien de commun avec tout ce que l'on voit dans le reste du monde; comment faire passer dans l'âme du lecteur cette impression mêlée d'admiration et de terreur qu'inspirent ces immenses amas de glaces entourés et surmontés de ces rochers pyramidaux plus immenses encore; le contraste de la blancheur des neiges avec la couleur obscure des rochers, mouillés par les eaux que ces neiges distillent, la pureté de l'air, éclat de la lumière du soleil, qui donne à tous ces objets une netteté et une vivacité extraordinaires; le profond et majestueux silence qui regne dans ces vastes solitudes, silence qui n'est troublé que de loin en loin par le fracas de quelque grand rocher de granit ou de glace qui s'écroule du haut de quelque montagne; et la nudité même de ces rochers élevés, où l'on ne découvre ni animaux, ni arbustes, ni verdure. et quand on se rappelle la belle végétation, et les charmans paysages que l'on a vus le jours précédens dans le basses vallées, on est tenté de croire qu'on a été subitement transporté dans un autre monde oublié par la nature, ou sur une comète dans son aphélie. la vue du montanvert ne donne de celle-ci qu'une idée très-imparfaite; là on ne voit qu'un seul glacier, au lieu que d'ici vous voyez les trois grands glaciers des bois, de léchaud et du tacul, sans compter un grand nombre d'autres moins considérables qui, comme celui du taléfre, versent leurs glaces dans les glaciers principaux. «les rochers innombrables que l'on voit au-dessus de ces glaciers sont tous de granit, car s'il y a, comme j'en suis certain, des rochers feuilletées, interposées entre ces granits, des _gneufs_, par exemple, ou des roches de corne; comme elles étoient plus tendres que les granits, leurs parties faillantes ont été détruites par les injures de l'air, et il ne reste plus que leurs bases, cachés au fond des gorges qui séparent les hautes pyramides.» this is a fact which, independent of the good authority we have here, we would have been naturally led, from the theory, to suppose. for, in wearing out the solid mass, which had been once continuous among those mountains, something must have determined the situation of those valleys; but what so likely as some parts more destructible by the wasting operations of the surface than others, which are therefore less impaired, and remain more high. now, whatever may be our theory with regard to the origin or formation of these solid masses of the globe, this must be concluded for certain,--that what we see remaining is but a specimen of what had been removed,--and that we actually see the operations by which that great work had been performed: we only need to join in our imagination that portion of time which, upon the surest principles, we are forced to acknowledge in this view of present things. chap. iv. _the same subject continued, in giving still farther views of the dissolution of the earth._ to have an idea of this operation of running water changing the surface of the earth, one should travel in the alps; it is there that are to be seen all the steps of this progression of things, and so closely connected in the scene which lies before one, that there is not required any chain of argument, or distant reasoning from effect to cause, in order to understand the natural operations of the globe, in the state of things which now appears. so strongly are the operations of nature marked in those scenes, that even a description is sufficient to give a lively idea of the process which had been transacted. with this view, i shall here transcribe, from the _tableau de la suisse_, a description of that remarkable passage by the mountain of st. gothard, from switzerland to italy, hoping, that, even independent of the illustration hereby given to the theory, the reader will be pleased to see such a picture of that country as will either excite new ideas in a person who has not seen such scenes, or call up those which it is proper for a naturalist to have[ ]. [footnote : tableaux de la suisse discours, etc. p. . route d'altorf au st. gothard.] «nous allons donner les observations que nous avons faites, en montant le saint gothard par le côté septentrional, et nous terminerons ce que nous avons à dire par la description du haut de cette montagne. il y a aux environs d'altorf, chef-lieu du canton d'uri, de grands terrains couverts de pierres roulées, dont la plus grande partie est amenée par le schechen, torrent qui descend de la vallée du même nom, et l'autre par la reuss qui descend du st. gothard. sans se donner beaucoup de peines, on y a la facilite de voir et d'examiner une grande variété de pierres d'espèces différentes et de connoître d'avance les rochers qui composent les montagnes qu'on va parcourir; nous répétons ici que toutes les pierres arrondies ont pris cette forme par le roulis qu'elles ont essuyées dans les torrens, en se précipitant avec les eaux qui les ont amenées: plus nous avons parcouru de montagnes, plus nous nous sommes confirmés que cette observation étoit vraie et exact. si on a la constance de suivre une espèce jusqu'au lieu de son origine ou position premiere, on l'y trouvera anguleuse, et n'ayant subi d'autres changemens que celui que le tems imprime à toutes les substances qui restent en place; on verra qu'à mesure qu'elles s'éloignent de leur premiere position leurs angles et leurs parties saillantes se détruisent, et qu'elles finissent par prendre la forme ronde ou approchante, en raison de leurs dureté et du chemin qu'elles auront parcouru. nous renvoyons à ce sujet ce qui a été dit vers le commencement de ces observations, en parlant du trient. nous ajoutons seulement qu'il n'y a guère d'espèce de pierres roulées dans les montagnes, dont nous n'ayons pas trouvé les rochers analogues, et qu'avec du tems et les courses convenables, en observant bien les directions des montagnes et des torrents, on les trouveroit toutes. altorf est entouré de très-hautes montagnes, des vallons aboutissent de tous côtes dans ses environs, parce-que c'est le lieu le plus bas où les eaux vont se jetter dans le lac de wahlasthall ou de lucerne, à l'extrémité duquel altorf est situé; le vallon est assez couvert dans le bas, il est cultivé dans quelques parties, et il y a des arbres fruitiers; c'est sur-tout aux environs de birglen qu'on rencontre beaucoup de pierres roulées et des rochers amenés par les eaux. «les rochers sont de pierre calcaire, et continuent jusqu'à silenen à deux lieues d'altorf; les montagnes sont fort hautes et fort escarpées des deux côtés du vallon, de beaux près sont dans le bas; quelque arbres fruitiers et sur-tout des noyers sont à mi-côte, et entre les rochers, des forêts de sapins. avant d'arriver à silenen, on apperçoit le glacier de tittlis; il est sur le territoire d'engelberg, et on trouve encore quelques hêtres; derrière les montagnes boisées il s'en élève d'autre nues et arides. des points et des vues admirables par la dégradation des montagnes et pour le sauvage, s'offrent de toutes parts. des chalets, des habitations isolées, sont situés au pied des plus affreux rochers qui les menacent d'une ruine prochaine. l'habitant y vit sans crainte, entouré de son pré et de son petit bien dont il est tranquille possesseur. «la chaleur concentrée dans ce vallon y fait mûrir différentes productions peu recherchées; à la verité, ce sont des fruits fort communs, excellens pour le pays, parce qu'on n'y en connoit pas de meilleurs. c'est du petit village d'amsteeg entouré de fort hautes montagnes, qu'on commence à monter ce qu'on nomme le saint gothard general: le chemin devient plus roide, la reuss y est plus resserrés et roule ses eaux dans un lit fort profond et très-escarpé, des torrens des cascades, tombent de différens endroits des deux côtés de ce vallon et de belles forêts de sapin, où il y a des arbres prodigieux pour la hauteur, varient les points de vues; on s'élève beaucoup au-dessus du fond des vallons par des chemins rapides: l'exposition plus heureuse fait cultiver du jardinage et des arbres fruitiers; il y a beaucoup de chanvre dans ces environs. de l'autre côté du vallon, sur la gauche de la reuss, est une usine ou on fabriquoit de l'alum et du vitriol, les travaux ont cessé, ces établissemens et l'exploitation des mines sont peu connus et peu suivis en suisse. la reuss semble toujours s'enfoncer d'avantage, par-tout elle roule ses flots avec bruit et fracas, elle s'est creusée un lit à des profondeurs incroyables; il n'y a point d'endroit ou l'on puisse mieux voir cet étonnant travail des eaux que sur le pont du pfaffensprung, à une demi-lieue de vassen; il est à une hauteur si effrayante que le premier mouvement, quand on regarde au bas du pont, est de se tenir au parapet, et le second de le quitter, dans la crainte qu'il ne manque, ce n'est que par réflexion qu'on y revient, on voit la progression et le travail successif de l'eau du haut jusqu'en bas; la roche a des sinuosités où des angles arrondis, rentrans et faillans, alternativement de chaque côté, et dont saillans sont opposes aux rentrans, de façon qu'il reste peu d'espace pour apercevoir l'eau, ce canal ou ce, gouffre n'ayant pas plus de deux toises et demie de large. depuis silenen on ne voit plus de pierres calcaires, les rochers sont schisteux argileux, mêlé de beaucoup de quartz; le lit de la reuss est rempli de granits, mais qui viennent des montagnes supérieures. au-dessus du pont, dont nous venons de faire mention, on rencontre un passage des plus pittoresques, composé de moulins, de scieries, de chutes d'eau, dominés par le village de vassen, et entourés de montagnes fort extraordinaire. une roche argileuse sur un plan incliné, s'est détachée de la hauteur, et a emporté un pont et un moulin. «on monte beaucoup après avoir passé vassen; ces environs sont d'une variété étonnante pour la beauté et la singularité des paysages. des nappes d'eau, des cascades qui se précipitent de roches en roches, forment dix et quinze chutes avant de se perdre dans les sapins qui contrastent avec la blancheur des eaux toutes réduites en écume. des maisons d'une construction particulière, placées contre les rochers pour les mettre à l'abri des avalanches, des poutres jetées sur différentes masses de rochers pour passer la reuss et autres torrens dont les eaux sont bouillonnantes et jaillissantes, des arcades de pierres pour joindre des rochers suspendus sur ces précipices, rochers de mille formes bizarres occupent le voyageur, et ne lui donnent plus le tems d'apercevoir les mauvais pas qu'il franchit. il y a sans doute des hommes assez malheureux, qui ne verroient que des dangers, et ne seroient occupés que de leurs craintes et des terreurs paniques; c'est en effet une grande privation de ne pas sentir les beautés de la nature, elle devient un malheur réel quand ce plaisir se trouve remplacé par des angoisses et de la frayeur. un tableau d'un autre genre nouveau, et pour lequel les expressions manquent, est une forêt rasée et abattue par une avalanche, il y a quelques années, ces sapins de plus de cent pied de long, ont eu le tems de perdre leurs feuilles et de permettre à la vue de passer à travers cette énorme quantité de bois et de branches entre lacées de mille manières bizarres, et d'apercevoir des rocs épars, des eaux qui circulent autour, et tombent quelque fois en cascades. c'est une spectacle qui devient effrayant quand on pense à la force et à la violence du moyen qui a pu occasionner un pareil effet. on recueille dans ce canton la résine des mélèzes. quoique vassen soit déjà fort élevé, on y cultive encore quelque jardinage, et il y a aussi quelque cerisiers sauvages. il y a environ cinq-lieues jusqu'à altorf. «après avoir passé vassen, on trouve cinq ou six superbes cascades formées par la reuss. elle fait un bruit à étourdir: la chaleur qu'il faisoit, avoit procuré une abondante fonte de neige, et l'eau avoit beaucoup augmenté depuis le matin. des bouleaux, des sapins, et des mélèzes, groupés ensemble, formoient des contrastes agréables par la variété et le mélange des différens verts. les chemins sont faits à grand frais et avec beaucoup de soin; on a jetté des arcades en différens endroits pour joindre les rochers, et faire passer les chemins par-dessus; on entend mugir la reuss sous ses pieds elle écume par-tout, il faut être accoutumé à ce spectacle pour n'en pas être effrayé. les rochers de droite et de gauche sont par-tout à pic et d'une granit, qui est jaunâtre dans différens endroits; dans d'autres, il est décomposé, passant à l'état d'argile; c'est le felds-path qui subit le premiere ce changement. des quartiers de rochers des parties de montagnes sont épars; des chalets, des habitations solitaires sont placé aux environs des endroits où il y a quelque pâturage. il y a un de ces rochers qui est une belle masse de granit, appellée la pierre du diable; on n'oublie pas de la faire remarquer, parce qu'il y a un conte populaire à son sujet que de graves auteurs nous ont conservé. le vallon se rétrécit beaucoup avant d'arriver à gestinen. «on a élevé par-tout de murailles à de très-grandes hauteur pour faire le chemin. tout ce travail, vu le local, est incroyable pour la difficulté; de gros blocs de granits sont rangés sur les bords du chemin pour servir de barrières dans les endroits les plus dangereux. ces passages sont si étroit qu'il faut peu de chose pour les interrompre. le pont du diable est d'une seul arche à plein ceintre de quatre toises d'ouverture deux et demie de large, et de douze toises d'élévation au-dessus de l'eau; le fracas et la rapidité avec laquelle l'eau passe sous ce pont, ne permettent gueres qu'on la considère tranquillement de dessus le pont, on est toujours tenté de s'en éloigner.--la distance depuis gestinen jusqu'à teufelsbruck ou pont du diable, qui est environ deux lieues, suffit pour prouver ce que nous disons; cette vallée, qu'on nomme schollenen, offre à chaque pas des difficultés vaincues, des rochers franchis, des intervalles comblés par des murailles, où il a fallu employer des montagnes de pierres. «les chemins sont pavés partout mieux que dans beaucoup de villes; des chevaux et des mulets chargés les fréquentent toute l'année; et dans quels pays ces grands travaux ont-ils été exécutes? dans un véritable chaos de rochers et montagnes dont partie sont bouleversés, et l'autre paroît prête à s'écrouler sur le passant, qui ne voit sous ses pieds que des écueils, des gouffres et des précipices, au fond desquels roule un torrent écumant et furieux. si les rochers sont menaçans, les avalanches sont encore plus dangereuses dans ce redoutable passage; il n'y a point d'année qu'il ne périsse des hommes et des bêtes de somme; on fait voir un endroit où une avalanche transporta à plus de cent toises au-dela de la reuss, dix-neuf chevaux et mulets chargés ainsi que leurs conducteurs; dans d'autres endroits des quartiers de rochers prodigieux qui ont été déplacés et transportés de même. «après avoir passé le pont du diable, le chemin tourne à gauche, puis à droite, pour monter une rampe assez rapide, très-bien pavée, qui conduit à une ouverture dans le rocher, c'est le seul passage qui se presente, nommé urner-loch, trou du pays d'urner ou urseren; un rocher fort élevé est sur la gauche, et les cascades de la reuss à droite; l'entrée du passage est obscure, c'est une galerie souterraine pratiquée dans le roc, haute de neuf pieds environ de façon qu'un homme peut y passer à cheval, de onze pieds de large et trente-deux toises de long; on a pratiqué dans le milieu une ouverture pour donner du jour; cette roche est toute de granit, ainsi que celles qui sont autour du pont du diable; il y a environ soixante ans que cette galerie a été ouverte; le chemin passoit auparavant en dehors sur une espèce de pont qui tournoit le rocher, et se trouvoit exactement suspendu et fort mal assuré au-dessus des cascades de la reuss; de frequens accidens, de grands frais pour reconstruire et entretenir ce pont, souvent entraîné par les eaux, ont necessité l'ouverture de ce passage. «en sortant de ce passage obscur, on est surpris d'entrer dans une plaine ouverte, riante et couverte de verdure, et de voir couler à côté de soi une onde limpide et tranquille. ce tableau est d'autant plus frappant qu'on vient de voir le contraste le plus effrayant; ce passage souterrain est comme le rideau qui se lève entre deux décorations, dont l'une representoit le chaos et le bouleversement de la nature, et l'autre celle de la nature naissante et parée des premiers et des plus simples ornemens; cette plaine est unie, de forme ovale, couverte d'un vaste gazon et de pâturages, entre lesquels serpente doucement la reuss: sur ces bords il y a quelques buissons et peu d'arbres, ce sont des aulnes. des cabanes de bois, des chalets isolés et solitaires sont répandus ca et là à l'entrée du vallon: à gauche est le village d'in-der-matt bâti en pierres, et à neuf; dans le fond celui de hospital et situé sur le penchant d'un coteau, il est dominé par une grosse tour: les montagnes du st. gothard servent de fond au tableau, elles sont trop éloignées pour laisser apercevoir leur aridité; des montagnes nues, couvertes d'une verdure légère sans arbres et sans buissons, bordent les deux côtés du vallon: enfin tout paroît jeune et d'une création nouvelle au premier coup d'oeil, qui met le spectateur dans l'état où est un homme à son réveil après un rêve épouvantable, où il n'a vu que des objets effrayans; il se trouve heureux et content d'être en sûreté et hors des dangers qui le menaçoient, tant les impressions de son rêve lui sont encore présentes. «ce vallon offre des remarques intéressantes pour l'histoire naturelle, sa position, sa forme, et son nivellement ne laissent aucun doute que cet emplacement n'ait été le séjour des eaux; en examinant les bords du lit de la reuss, on reconnoît que le terrain de ce vallon est par couches horizontales de pierres argileuses; le pied des montagnes qui entourent le vallon sur la droite est de pierre calcaire grise, à la même hauteur, et à mi-côte, sur la gauche, on trouve de la pierre ollaire. voilà encore une de ces circonstances où il seroit intéressant de connoître la hauteur exacte de cette pierre calcaire, et de pouvoir comparer son niveau avec d'autres que nous avons déjà observé être aussi déposées au pied des montagnes dans de petits vallons fort élevés, analogues à celui dont il est question. quelque secousse aura rompu l'enceinte de rocher qui fermoit ce bassin: l'écoulement des eaux aura achevé de creuser ce passage, où coule actuellement la reuss, et le vallon qui est au-dessous. quoique les angles rentrans et saillans des montagnes ayent lieu dans quelque endroits, il s'en faut de beaucoup que ce soit une règle certaine: le vallon qui descend du saint gothard à altorff est une de ces exceptions. une autre chose remarquable dans ce vallon, c'est qu'au sortir du passage souterrain que nous avons dit être creusé dans le granit, il y a tout à côté sans interruption, et formant la même masse de rocher, de la pierre schisteuse micacée, mêlée de quartz, dont les couches sont perpendiculaire, se fendent et tombent par morceaux, qui ont la forme de poutres ou de bois équarris. cette espèce de roche est aussi haute que celle de granit, et composée, dans des proportions différentes, des mêmes parties intégrantes que le granit; n'a-t-elle pas été apposée et formée contre celle de granit, qui assurément doit être plus ancienne, puisqu'elle est enveloppée par la roche schisteuse[ ]? [footnote : here is an example of the junction of the granite with the schistus; and probably here will be a proper opportunity of investigating the formation of those two things. our author here supposes the granite to be the primary, and the schistus to be the secondary body; on the contrary, i believe that schistus to be the primary in relation to the granite, and that the granite had invaded the schistus, as will be made to appear in its proper place.] ce vallon, d'une bonne lieue de longueur sur moitié de largeur, peut occasionner bien des réflexions; nous avons été obligé de passer rapidement sur ces objets, nous ne faisons que les indiquer. au-haut de la montagne rapide, qui est au-dessus du village d'in-der-matt, il y a un petit bois de sapins, auquel il est défendu de toucher sous peine de la vie. il est réservé contre les avalanches; ce sont les seules arbres qu'on voie sur les hauteurs environnantes; derrière ce bois on apperçoit un glacier d'où descend un torrent qui va se jetter dans la reuss; il amène, ainsi que les autres qui descendent de ce coté, des pierres schisteuses micacées, mêlées de quartz, de même nature que celle qui est à coté du passage souterrain. on monte par un beau chemin au village de hospital, qui dépend aussi du pays d'urseren: tout ce canton est renommé pour ces excellens fromages. il n'y a que des pâturages et point d'autre culture. le bois, qui est de première nécessité dans un pays aussi froid, aussi élevé et toujours entouré de neige, y manque totalement, on est obligé de l'aller chercher dans la vallée de schollenen, et on traine sur la neige le bois de charpente. le village de hospital est situé sur des roches schisteuses mêlées de mica et de quartz, elles sont bleues, verdâtres, et grises. c'est à hospital qu'est la rencontre de différens chemins pour passer le saint-gothard; il y en a un qui venant du vallais, passe à côté du glacier du rhône et par la montagne de fourk. un second qui vient des grisons, passe par disentis et chiamut entre les sources du bas rhin. ce sont des sentiers: qu'on juge de ce qu'ils peuvent être d'après le grand chemin que nous venons de décrire, qui conduit de la suisse en italie. «sur la droite du village de hospital est un vallon que nous avons visité jusqu'au village de zum-d'orff, à une grand demi-lieue. il y règne aussi une couche de pierre calcaire à même hauteur, au bas de la montagne qui renferme le vallon, et nous prions de remarquer qu'elle est aussi sur la droite, et que sur la gauche il y à de pierre ollaire; une masse énorme de cette espèce, sous laquelle on travailloit depuis long-tems pour en tirer de quoi faire des poêles, ayant perdu son équilibre, est tombée sur le côté. les rochers qui dominent, sont des rochers schisteuse micacées avec du quartz. ce dernier village fait aussi partie de la vallée d'urseren, c'est le pays habité le plus élevé de l'europe; les habitons sont forts et robustes; les montagnes de ce canton étant nues, arides, et fort rapide, les avalanches y sont fréquentes. «c'est au sortir de hospital qu'on monte véritablement le mont saint gothard: le chemin est escarpé, pavé, et bien entretenu. par un vallon à droite descend le garceren, torrent qui vient des glaciers; son eau est blanchâtre, se jette dans la reuss, et en trouble la limpidité; les rochers sont de plus en plus dépouillés, secs et arides, on trouve les derniers buissons, des aulnes rabougris. la reuss tombe de rocher en rocher, des blocs et des quartiers énormes, qui remplissent son lit, lui barrent souvent le passage; ses eaux s'élancent par-dessus quand elle ne peut le contourner; on ne voit enfin que des rochers, des abymes et des précipices; on marche néanmoins en sûreté au milieu de ce désordre de la nature; les chemins sont bien pavés, et assez larges pour que deux chevaux ou deux mulets chargés puissent y passer de front. sur un rocher à droite, à une lieue de hospital environ, on trouve taillés dans le roc les limites entre le pays d'urseren, et la partie italienne ou vallée de livenen; ainsi tout sommet du st. gothard appartient à la partie italienne, qui est actuellement sujette du canton d'uri. on parvient enfin sur un terrain plus uni, et une espèce de plateau, c'est le haut du saint gothard; à une demi-lieue sur la droite, entre des rochers forts hauts, forts escarpés et à pic, est une espèce d'entonnoir, ou se rassemblent les eaux des neiges fondues; elles y forment le petit lac de luzendro, gelé le trois quarts de l'année, d'ou la reuss tire sa source en partie; car le glaciers du mont de la fourche ou fourk dans le haut vallais, fournissent aussi un torrent qui est regardé comme la seconde source de la reuss; le rhône prend sa source dans la partie opposée du même glacier. le haut du saint gothard est un vrai vallon, puisque des cimes, des pyramides, des montagnes prodigieuses, composées toutes de rochers, s'élèvent au-dessus, et l'entourent de tous côtés. l'espace qui est entre ces rochers a une forme a-peu-prés circulaire; il paroît avoir été un fond qui a été élevé et comblé jusqu'au point ou il est par les débris des montagnes qui le dominent, et qui s'y amoncèlent encore actuellement sous nos yeux; il a une espéce de niveau qui va un peu en pente du côté du midi, et du côté du nord par lesquels se fait l'écoulement des eaux fournies par la fonte des neiges, dont la reuss et le tessin sont les canaux. des masses étonnantes de rochers remplissent la surface de ce vallon: elles y sont placées dans une désordre qui ne ressemble point aux positions des rochers actuels, et autorise à croire qu'elles y ont été jetées et culbutées au hazard. ces masses isolées sont toutes de granit, composé de quartz, de feldspath, et de mica verdâtre; le chemin qui traverse ce vallon tourne autour de ces masses. il faut que les pics élevés qui bordent ce vallon ayent été beaucoup plus hauts qu'ils ne le sont actuellement pour avoir pu fournir à combler cette étendue, qui a une lieue au moins. il n'est pas douteux non plus, que les vastes montagnes qui font au pied de toutes celles qui forment l'enceinte du gothard, au moyen desquelles on trouve un accès plus facile, et des rampes moins rapides pour s'élèvent comme par degrés à cette hauteur, qui composent enfin ces montagnes de seconde et de troisieme formation, ne doivent leur existence qu'aux débris de ces colosses qui dominent tout. l'examen de ce qui se passe sous nos yeux journellement, ne peut nous laisser aucun doute sur l'abaissement de montagnes. il n'y a point de torrent, point d'écoulement d'eaux, quelque petit qu'il soit, qui n'entraîne en descendant des montagnes, des terres, des graviers, ou des sables, pour les porter plus bas. les grands torrens, les fleuves, les rivières, gonflés par les fontes subites des glaces et des neiges, entraînent des rochers entières, creusent de vastes et profonds ravins; ces masses de rochers diminuent par le choc et le frottement qu'elles essuient entre elles, et sur les rochers sur lesquels elles passent, dont elles occasionnent reciproquement la destruction; ce sont des débris de cette espéce de trituration qui troublent les eaux, et dont le dépôt élève insensiblement les bords des rivières, forme le limon fécondant de nos plaines, et va former jusque dans le sein des mers ces atterrissemens, ces barres, et ces bancs qui en reculent les bornes. les rochers les plus durs, ces granits que les meilleurs outils ont tant de peine à façonner, ne résistent point au tems et aux intempéries des saisons; leur superficie se dénature et se décompose souvent au point de ne pas les reconnoître: des lichens, des petites mousses s'insinuent dans leur tissu, l'eau y pénètre, et la gelée sépare leurs parties; s'ils se trouvent placé sur une pente de façon à pouvoir être entraîné par les eaux, la plus grosse masse est bientôt réduite à peu de chose, apres avoir parcouru un plan incliné; quels changemens ne doit pas avoir opéré cette marche constante de la nature. a quel point n'est elle pas rendu méconnoissable la superficie du globe que nous habitons. pour peu qu'on réfléchisse que les montagnes fournissent continuellement aux plaines, et que celle-ci ne rendent rien aux montagnes, on pourra se faire quelque idée des changemens que la révolution des siècles à du opérer. aussi n'est ce que sur les hautes montagnes qu'on apperçoit encore parmi leurs vastes débris, les matériaux qui ont servi et servent aux créations nouvelles que la nature opère journellement, qu'ils sont grands, qu'ils sont majestueux ces antiques débris! que l'homme est petit, qu'il est confondu quand il ose y porter un regard curieux!» in this picture of the alps, there is presented to our view the devastation of solid rocks by agents natural to the surface of the earth; here is the degradation of mountains in the course of time. of these ruins plains are formed below; and these plains are continually shifting their place, in affording materials to be washed away and rolled in the rivers, and in receiving from the higher grounds the spoils of ruined rocks and mountains. such operations are general to the globe, or are to be found over all this earth; but it is not every where that we have descriptions proper to give just ideas of this subject, which escapes the common observation of mankind. as i have given an example in the alps of savoy and switzerland, it may be proper to give some view of the same operation in those of the pyrénées (essai sur la minéralogie des monts pyrénées) page . «la vallée d'aspe est arrosée dans toute sa longueur, par le gave, qui prend sa source vers les frontières d'espagne: dans les temps de pluie et d'orage, cette rivière est colorée en rouge par des terres composées de schiste rougeâtre, qui s'éboulent: des montagnes de gabedaille et de peyrenère: au reste les eaux du gave profondément encaissées dans leur lit ne peuvent plus contribuer à la fecondité des plaines qu'elles ont formées. «on observe, en suivent cette rivière que lorsque les montagnes courent parallèlement, les angles faillans qu'elles forment correspondent aux angles rentrans; cette règle générale sert à établir que les vallées des pyrénées, qu'il faudroit plutôt appeler _de gorges_ puisqu'elles n'ont qu'une demi-lieue dans leur plus grande largeur, sont l'ouvrage des eaux; mais doit on les ranger parmi celles que m. de buffon a démontré avoir été creusées par les courans de la mer, ou les supposer formées par les torrens qui se précipitent des montagnes? «ne croyez pas, dit m. d'arcet, en faisant mention des vallées des pyrénées, que les eaux aient pris ces routes parce qu'elles les ont trouvées frayées antérieurement à leur cours; ce sont les eaux même d'en-haut, qui, se ressemblant peu-à-peu, se sont ouvert de force ces passages: elles se sont creusé ces lits dans le temps passés, comme elles les creusent encore tous les jours. _voyez la discours sur l'État actuel de pyrénées, p._. . (p. .) «les pierres que les eaux du val de canfrac entraînent, sont rarement usées dans leurs angles; on en trouve peu dont la figure soit arrondie, comme celle des pierres que roulent les torrens de la partie septentrionale des pyrénées; le sol des environs de jacia, plus élevé que celui des plaines du côté de la france, s'oppose a ce qu'elles soient emportées à d'assez grandes distances, et avec la rapidité necessaire pour recevoir, par un long frottement, une figure arrondie: on ne voit point de pierres roulées dans les plaines qui entourent cette ville, les bancs calcaires ne sont couverts que d'une croûte de terre peu épaisse; un telle formation diffère de celle qu'on observe au pied des monts pyrénées, du côté de la france, ou le sol de plusieurs contrées est composé des débris que les rivières y ont déposés[ ]; une partie de l'Égypte, selon hérodote, a été pareillement formée des matières que le nil y a apportées; aristotle la nomme l'ouvrage du fleuve: c'est pourquoi les Éthiopiens se vantoient que l'Égypte leur étoit redevable de son origine. les habitans de pyrénées pourroient dire la même chose de presque toutes les contrées situées le long de la chaine septentrionale, depuis l'océan jusqu'à la méditerranée, et qui forment cette espace d'isthme qui sépare les deux mers: c'est ainsi que la nature change continuellement la surface de notre globe; elle élève les plaines, abaisse les montagnes; et l'eau est principal agent qu'elle emploie pour opérer ces grandes révolutions; il ne faut que du temps, pour que le mot de louis xiv. à son petit-fils, se réalise. la postérité pourra dire un jour; _il n'y a plus de pyrénées_. on conçoit combien cette époque est éloignée de nous. m. gensanne a trouvé, par des observations qu'il pretend non équivoques, que la surface de ces montagnes baisse d'environ dix pouces par siècle; ainsi, en les supposant seulement de quinze cens toises au-dessus du niveau de la mer, et toujours susceptibles du même degré d'abaissement, il s'écoulera un million d'années avant leur destruction totale.» [footnote : the notion, that the water-worn gravel, which we so frequently find upon the surface of the earth, had been the effect of rivers transporting the rocks and stones, is not accurate or in perfect science. that stones are thus continually transported is certain; it is also indisputable, that in this operation they are broken and worn by attrition, more or less; but, that angular stones of the hardest substance are thus made into that round gravel, which we find so abundantly in many places forming the soil or loose materials of the surface, is a conclusion which does not necessarily follow from the premises, so far as there is another way of explaining those appearances, and that by a cause much more proportioned to the effect. the view which i take of the subject is this; first, that those water-worn materials had their great roundness from the attrition occasioned by the waves of the sea upon some former coast. secondly, that, after having been thus formed by agitation on the shores, and transported into the deep, this gravel had contributed to the formation of secondary strata, such as the puddingstone which has been described in part i. chap , and ; and, lastly that it has been from the decay and resolution of those secondary strata, in the wafting operations of the surface, that have come those rounded siliceous bodies, which could not be thus worn by travelling in the longest river.] i do not know in what manner m. gensanne made his calculation; i would suspect it was from partial, and not from general observations. we have mountains in this country, and those not made of more durable materials than what are common to the earth, which are not sensibly diminished in their height with a thousand years. the proof of this are the roman roads made over some of those hills. i have seen those roads as distinct as if only made a few years, with superficial pits beside them, from whence had been dug the gravel or materials of which they had been formed. the natural operation of time upon the surface of this earth is to dissolve certain substances, to disunite the solid bodies which are not soluble, but which, in having been consolidated by fusion, are naturally separated by veins and cutters, and to carry those detached bodies, by the mechanic force of moving water, successively from stage to stage, from places of a higher situation to those below. thus the beds of rivers are to be considered as the passages through which both the lighter and heavier bodies of the land are gradually travelling; and it is through them that those moveable bodies are from time to time protruded towards the sea shore. but, in the course of rivers, it often happens that there intervenes a lake; and this must be considered as a repository for heavy bodies which had been transported by the force of running water, in the narrow bed through which it was obliged to pass; for, being arrived in the lake, the issue of which is above the level of its bottom, the moving water loses its force in protruding heavy bodies, which therefore it deposits. thus the bottom of the lake would be filled up, before the heavy materials which the river carries could be made to advance any farther towards the sea. reasoning upon these principles, we shall find, that the general tendency of the operations of water upon the surface of this earth is to form plains of lakes, and not, contrarily, lakes of plains. for example, it was not the rhône that formed the lake of geneva; for, had the lake subsisted in its present state, while the rhône had transported all the matter which it is demonstrable had passed through that channel from the alps, the bed of the lake must have been made a plain through, which the river would continue to pass, but in a changing channel, as it does in any other plain. we are therefore led to believe, that the passage of the rhône through the lake, in its present state, is not a thing of long existence, compared with the depredations which time had made by that river upon the earth above the lake. but how far there are any means for judging, with regard to the causes of that change which must have taken place, and produced the present state of things about this lake, can only be determined by those who have the proper opportunity of examining that country. if lakes are not in the natural constitution of the earth, when this is elevated from the sea into the place of land, they must be formed by some posterior operation, which may be now considered. there are in nature, that is, in the natural operations of the globe, two ways by which a lake may properly be formed in a place where it had not before existed. one of these is the sliding or overshooting of a mountain or a rock, which, being undermined by the river, and pressed by its weight, may give way, and thus close up the defile through which the river had worn for itself a passage. the other is the operation of an earthquake, which may either sink a higher ground, or raise a lower, and thus produce a lake where none had been before. to which, indeed, may be added a third, the dissolution of saline or soluble earthy substances which had filled the place. so many must have been those alterations upon the surface of the earth which we inhabit, and so short the period of history by which, from the experience of man, we have to judge, that we must be persuaded we see but little of those operations which make any sensible change upon the earth; and we should be cautious not to form a history of nature from our narrow views of things; views which comprehend so little of the effects of time, that they may be considered as nothing in the scale by which we are to calculate what has passed in the works of nature. to form an idea of the quantity of the solid land which has been carried away from the surface of the earth, we must consider our land, with the view of a mineralist, as having all the soil and travelled materials removed, so as we might see the terminations of all the strata, where these are broken off and left abrupt. now, the generality of those strata are declined from the horizontal plane in which they had been formed, and shew that the upper extremity had been broken off and carried away; and the quantity of that which has been carried away, since the time of the formation of those strata, so far as may be judged from the nature and situation of what remains, must be concluded as very great. this is best to be observed in mountainous countries, where not only the causes of this destruction of the land are more powerful, but the opportunities of investigating the effects more frequent, from the washing away of the loose soil or covering. the correspondent angles of the valleys among mountains is a subject of this nature, in which may be perceived a visible waste of the solid mountain which has those correspondent angles. i am happy to have an authority so much better than my own observations to give on this occasion, where the question relates to what is common or general in these appearances. it is that of m. de luc, lettres physique et morales, tom. . p. . «mais avant de finir sur les montagnes _primordiales_, il faut que je revienne à ces _angles saillans et rentrans alternativement opposés_, qui lorsque mr. bourguet les annonça, firent un si grand bruit parmi les naturalistes qu'on ne douta plus que toutes les montagnes ne fussent l'ouvrage de la _mer_. voici ce que c'est que ce phénomène prétendu démonstratif. «lorsqu'on voyage dans les vallées, on va ordinairement en tournoyant; et quand un angle saillant oblige à courber la route, on trouve assez souvent un angle rentrant qui lui fait face, et la vallée conserve à peu près la même largeur. m. bourguet ayant fait cette remarque, et considérant que les bords opposés d'une rivière qui serpente, offrent la même opposition des angles saillans et rentrans, en conclut en général, que les montagnes avoient été formées par les courans de la mer. «si toutes les montagnes, et les _alpes_ par exemple, avoient tous les autres caractères qu'exige une telle formation celui-là sans doute ne paroîtroit pas les contredire; et l'on ne peut même disconvenir, qu'au premier coup d'oeil, ces zig-zags ne ressemblent beaucoup aux effets des eaux courantes. cependant ce caractère appartient bien plus aux eaux qui se frayent une route, qu'à celles qui font des dépôts. un rivière qui creuse son lit, se détourne à la rencontre d'un obstacle, et ronge le côté opposé; c'est ce qui produit ses méandres. mais on ne voit point les mêmes causes de zig-zags dans les courans au sein de la mer; à moins qu'il n'y ait déjà des montagnes. «en effet si l'on considère les montagnes et les collines qui par leurs couches et les corps étrangers qu'elles renferment, montrent sans équivoque qu'elles sont l'ouvrage des eaux, on les trouvera le plus souvent rangées sans ordre. quelquefois elles ne paroissent que des monceaux posés çà et là; comme dans une grand partie du _piémont_. ou si elles sont sous la forme de chaînes continues, on y trouve peu de parallélisme, c'est-à-dire de ces angles rentrans opposés aux angles saillans: tel est le jura. «mais si les courans de la mer ont trouvé des montagnes toutes faites, et qu'ils les ayent traversées, dans quelque sens que ce soit; ils se sont frayé des routes dans les endroits où la resistance étoit moindre, et ont rongé les bords de leurs canaux à la manière des rivières. on doit donc y trouver du parallélisme. «si maintenant on considère la chaîne des _alpes_, on verra qu'elle répond fort bien à cet effet naturel. quoique ces montagnes forment une chaîne dans leur ensemble, leurs parties supérieures ne montrent aucune sorte d'arrangement particulier, aucune trace de zig-zags: c'est dans le fond des grandes vallées, ou dans les coupures qui servent à l'écoulement des eaux, que ce parallélisme des côtés opposés se remarque; quoiqu'avec bien des exceptions. et ce qu'il y a de plus important à considérer, c'est que ces grandes vallées ou les angles saillans et rentrans forment l'engrènement le plus sensible, coupent ordinairement la chaîne en travers, au lieu de la suivre; ce qui annonce plutôt destruction qu'édification. «ainsi _les angles saillans et rentrans alternativement opposes dans les vallées des montagnes_, peuvent bien contribuer à prouver qu'elles ont été toutes sous les eaux de la _mer_; mais non que la mer les aît toutes faites. c'est ici donc un nouvel exemple de la nécessité de considérer attentivement les idées qui paroissent le plus naturelles au premier coup d'oeil: car cet aperçu étoit bien un de ceux qu'on est tenté d'admettre sans examiner autre chose que la vérité du fait.» here we have the testimony of this author concerning the nature of those causes by which the shape of the surface of the earth, in those regular appearances of corresponding parts, had been determined, viz. that these had been destroying operations, and not those by which the mountains had been formed. we differ, however, from this naturalist with regard to the particular agent here employed. it will be shown, in a subsequent chapter, that there is almost as little reason to conclude from this appearance, that the space between the correspondent angles had been hollowed by the currents of the sea, as that those angles had been formed by matters deposited in that shape and situation. farther, treating of the calcareous mountains, the same author observes, (lettre . p. .) «cette chaîne extérieure des _alpes_ évidemment d'origine _marine_, a cependant des caractères qui la distinguent de la plupart des autres montagnes de la même classe; et ces caractères semblent annoncer plus d'antiquité. je crois d'abord pouvoir les regarder comme les montagnes _secondaires_ les plus hautes de notre continent. (je ne parle ici que des montagnes marines.) ensuite leur destruction est beaucoup plus grande que celle d'aucune autre montagne de ce genre qui me soit connue: car elles sont presque aussi couronnées de pics que les _alpes primordiales_; et ces _pics_, étant par _couches_, montrent des restes d'anciens sommets qui devoient avoir une grande étendue. ce qui, joint à quelques dérangemens dans leurs couches, paroît indiquer que ces montagnes ont été exposées plus longtemps que la plupart des autres montagnes _secondaires_, aux revolutions qu'essuyoit le fond de la _mer_; et qu'elles en sont sorties déjà fort altérées.» there is at present no question concerning the particular shape in which the mountains of the earth had come out of the waters of the sea. we are considering the wasting of those mountains, in being exposed to the atmosphere and waters of the earth; and the operation that the sea may have had upon their surface, is a subject for judging of which we have not the smallest data, unless by taking the thing for granted, or supposing that the present state of things is that former shape after which we inquire. now, this is a species of reasoning that m. de luc would certainly explode; for he admits, as we shall afterwards find, great changes among the mountains of the alps, from the influences of the atmosphere, perhaps more rapid changes than we are disposed to allow. therefore, to call in the aid of the ocean, for the degradation of these secondary calcareous mountains, holds of no reason that i can see, unless it be that of diminishing the time which otherwise would have been required in bringing about those changes by the atmosphere alone. to conclude: whether we examine the mountain or the plain; whether we consider the degradation of the rocks, or the softer strata of the earth; whether we contemplate nature, and the operations of time, upon the shores of the sea, or in the middle of the continent, in fertile countries, or in barren deserts, we shall find the evidence of a general dissolution on the surface of the earth, and of decay among the hard and solid bodies of the globe; and we shall be convinced, by a careful examination, that there is a gradual destruction of every thing which comes to the view of man, and of every thing that might serve as a resting place for animals above the surface of the sea. chap. v. _facts in confirmation of the theory respecting the operations of the earth employed in forming soil for plants._ i have distinguished the mineral operations of the earth, by which solid bodies are formed of loose materials, as well as the resolving or decomposing operations which are proper to the surface exposed to the sun and atmosphere. i have also pointed out the end or intention of those several operations, and likewise the means by which they have been brought about. we may now turn our view to that part of the system in which an indefinite variety of soils, for the growth of plants and life of animals, is to be provided upon the face of the earth, corresponding to that diversity which, in the wisdom of nature, has been made of climates. in this last view, now to be considered, some confirmation should be given to the theory, in finding the soil, or travelled materials upon the surface of the land, composed of earth, that is, of sand and clay, of stones and gravel; the earth and stones as arising from the resolution and separation of the solids in the neighbourhood of the place; the gravel, again, as having often travelled from more distant parts. it would be very improper to adduce any example of a particular, where the force of the argument lies in the generality alone. it is enough to have mentioned the facts which are to be examined: every person of inquiry and observation will judge for himself how far those facts are true. but there is one general remark that may be made on this occasion, where the operations of the surface are concerned, and which may assist the investigation of this subject; it is with regard to the gravel or stones worn by attrition, which may have come from a distance. in proportion as hard and insoluble stones are near to their natural beds, they will be found with the sharp angles of their fracture, unless there may have been a cause of agitation and attrition on the spot; they will also be in greater quantity, _cet. par._ in this place; whereas the farther they may have travelled, they will naturally incline to be more rounded, and, in equal circumstances, will always be more scarce. we have thus principles by which to judge of every appearance in relation to the travelled materials of our soil. when, for example, we find an immense quantity of the hardest stones worn round by attrition, and collected not far distant from their native place, we cannot suppose that they have acquired their shape by the attrition in the distance they have travelled, but in an agitation which they must have received nearly in the place from whence they came. such is the gravel in the chalk country of england. around london, in all directions, immense quantities of gravel are round, which consists almost entirely of flint worn or rounded by attrition; but this is the very centre of the chalk country, at least of england; and no doubt the same appearances will be found in france. we must therefore conclude, that the south of england was under water when that gravel was formed; and that immense quantities of the chalk above had been destroyed by the agitation of the sea in preparing such quantities of gravel which still remain upon the land; besides the immense quantities which must have been dispersed all around during the operation, as well as carried into the sea by the rivers since the elevation of our land. it is not uncommon to find this gravel twenty or thirty feet deep; and masses are found of much greater thickness. were these masses of gravel formed in a deep hollow place, they would draw to no conclusion beyond the appearance itself; but they are, on the contrary, in form of hills; and therefore they serve as a kind of measure or indication of what had been carried away when these were left remaining. we may observe a series or a progress in those forming and destroying operations, by which, on the one hand, the flinty bodies, already formed in the mineral region, were again destroyed, in being diminished by their mutual attrition; and, on the other hand, those diminished bodies were again consolidated into one mass of flinty stone, without the smallest pore or interstice. this example is to be found in the puddingstone of england. it consists of flint pebbles, precisely like kensington gravel, penetrated or perfectly consolidated by a flinty substance. here are the two opposite processes of the globe carried on at the same time and nearly in the same place. but it must be considered, that our land was then in the state of emerging from the sea, and those operations of subterranean fire fit for elevating land was then no doubt exerted with great energy; at present, no such thing appears in this place. but, from the momentary views we have of things, it would be most unphilosophical to draw such absolute conclusions. the argument now employed rests upon the identity of the substance of the gravel with that of the entire flint, which is found in the chalk country; and it goes to prove that the sea had worn away a great deal of that chalk country above the place upon which this body of gravel is now resting; consequently that the sea had formerly flowed over that country covered with gravel, and had dispersed much of that gravel in transporting it to other regions, where that species of flint was not naturally produced. by a parity of reasoning, the gravel produced in the neighbouring regions, and which would be proper to those places, as consisting of their peculiar productions, must have been likewise dispersed and mixed with the surrounding bodies of gravel. but as in the country of which we are now treating, there are considerable regions, the different productions of which are perfectly distinct, we have a proper opportunity of bringing those conclusions of the theory to the test of observation. for this purpose, let us examine the different countries which surround the chalk regions of england, france, and flanders; if the gravel upon those neighbouring countries contain flint which the country does not naturally produce; and if the mixture of this flint among the gravel, which is proper to the country itself, be with regard to quantity in proportion to the vicinity of the flint country, the theory will then be confirmed; and there is no doubt that this is so. on the other hand, let us examine the gravel about london, which is far distant from any place that produces quartz; if we shall find a very small proportion of quartz gravel in this flinty soil, we may be assured that the quartz has travelled from a distance, and that the theory is thus approved. this is actually the case, and i have seen puddingstone containing quartz gravel among the flint. in confirmation of this view of the travelled soil, it may be observed, that in lower saxony about hamburgh, and for a great way to the south-west, the gravel is mostly of broken flint, such as is around the chalk countries: yet it is at a distance from the chalk of flanders; there is however at luxemburgh chalk with flint, the same as in england and france. therefore the flinty soil of that country, in like manner, demonstrates the great destruction of the solid parts, and illustrates the formation of soil by the remainder of the hard parts below, and the alluvion of other parts. there is most undoubted evidence that the solid body of our land had been formed at the bottom of the sea, and afterwards raised above the surface of the water; but, in the case which has now been described, it appears that the travelled soil of the surface of our land had been lately under the surface of the sea. we have thus therefore traced the different steps in the operations of nature, of which the last step may be considered as thus exposed to our view almost as much as the operations of man in building the pyramids of egypt. but surely there are other documents to be found in examining the different coasts of this island with attention; and there must be a consistency in the general appearance which never fails to attend on truth. from the south to the north of this island, there are, in many places, the most evident marks of the sea having been upon a higher level on the land; this height seems to me to amount to about or feet perpendicular at least, which the land must have been raised. some of those facts may now be mentioned. upon the banks of the thames, i have found sea shells in the travelled soil a considerable height above the level of the sea. in low suffolk there are great bodies of sea shells found in the soil which the farmers call _crag,_ and with it manure their land. i do not know precisely the height above the sea; but i suppose it cannot exceed feet. in the frith of forth there are, in certain places, particularly about newhaven, the most perfect evidence of a sea bank, where the washing of the sea had worn the land, upon a higher level than the present. the same appearance is to be found at ely upon the fife coast, where the sea had washed out grottos in the rocks; and above kinneel, there is a bed of oyster shells some feet deep appearing in the side of the bank, about or feet above the level of the sea, which corresponds with the old sea banks. i have seen the same evidence in the frith of cromarty, where a body of sea shells, in a similar situation, was found, and employed in manuring the land. there are many other marks of a sea beach upon a higher level than the present, but i mention only those which i can give with certainty. we have been considering an extensive country more or less covered with gravel; such is england south of yorkshire; both upon the east and west sides of the island. this country having no high mountainous part in the middle, so as to give it a considerable declivity towards the shores and rivers, the gravel has remained in many places, and in some parts of a considerable thickness. but in other parts of the island, where the declivity of the surface favours the transportation of gravel by the currents of water, there is less of the gravel to be found in the soil, and more of the fragments of stone not formed into gravel. still, however, the same rule holds with regard to tracing the gravel from its source, and finding particular substances among the gravel of every region, in proportion to the quantity of country yielding that substance, and the vicinity to the place from whence it came. here are principles established, for the judging of a country, in some respects, from a specimen of its gravel or travelled stones. in this manner, i think, i can undertake to tell from whence had come a specimen of gravel taken up any where, at least upon the east side of this island. nor will this appear any way difficult, when it is considered, that, from portland to caithness or the orkneys, there are at least ten different productions of hard stone in the solid land which are placed at proper distances, are perfectly distinguishable in the gravel which is formed of them, and with all of which i am well acquainted. let us suppose the distance to be miles, and this to be divided equally into different regions of miles each, it must be evident that we could not only tell the region, which is knowing within miles of the place, but we could also tell the intermediate space, by seeing an equal mixture of the gravel of two contiguous regions; and this is knowing within miles of the place. if this be allowed, it will not seem difficult to estimate an intermediate distance from the different proportions of the mixed gravel. this is supposing the different regions to be in all respects equal, which is far from being in reality the case; nevertheless, a person well acquainted with the different extent and various natures of those regions, may make allowances for the different known circumstances that must have influenced in those operations, although it is most probable there will be others which must be unknown, and for which he can make no allowance. the author of the tableaux de la suisse has entered very much into this view of things; he has given us some valuable observations in relation to this subject, which i would here beg leave to transcribe[ ]. [footnote : discours sur l'histoire naturelle de la suisse, p. .] «nous avons dit précédemment que c'étoit entre orfière et liddes que nous avions vu les derniers granites roulés, on n'en rencontre plus dans tout le reste de la route jusqu'au haut du mont st. bernard. les rochers qui dominent ce sommet ne sont pas composés de granites, et quoiqu'on ne puisse aborder jusqu'à leur plus grande élévation, on peut juger de leurs espèces, par les masses qui s'en précipitent. d'où peuvent donc provenir ces masses roulées de granites qui se trouvent jetés et répandus sur le penchant et au bas de ce mont? il y a peut-être quelque montagne ou rocher de granite que nous n'avons pas été à portée de voir: il faudroit plus d'un mois pour faire un pareil examen et parcourir les montagnes environnantes, et faute de pouvoir parvenir à certains sommets, examiner scrupuleusement les fonds pour juger des hauts. de pareilles recherches sont plus difficiles et plus longues qu'on ne le croit communement quand on veut réellement voir et observer. beaucoup de vallons sont comblés à des hauteurs prodigieuses, par les amas et les débris provenant des montagnes supérieures: ils cessent d'être des vallons, pour former ou faire partie de montagnes. ces déplacement et des bouleversemens, changeant la direction et le courant des torrens, entraînent dans des parties bien opposées des débris qu'on croiroit devoir chercher et trouver ailleurs. on seroit induit en erreur, en voulant suivre toujours le cours actuel des eaux qui descendent des montagnes. ce n'est pas dans cette occasion seul mais l'allemagne, la corse, la sardaigne, et beaucoup de pays de hautes montagnes, nous out fourni également des exemples de masses de rochers roulés de différentes espèces dont il n'existoit pas de rochers pareils, dans toutes les parties élevées environnantes, à plusieurs lieues, à plusieurs journées de chemin, et souvent totalement inconnus dans les pays d'alentour. si nous avons remarqué les même espèces de rochers faisant corps, et attachés au sol, à une ou plusieurs lieues de distance; nous avons vu souvent que des montagnes plus hautes étoient entre ces masses roulées et les rochers, d'ou on auroit pu supposer qu'elles ont été arrachées: il repugne à croire que des masses, d'un poids prodigieux, ayent été transportées et roulées en travers d'un vallon profond, pour remonter et passer de l'autre côté d'une montagne. nous abandonnons, a ceux qui travaillent dans le cabinet, à l'arrangement du globe, la recherche des moyens que la nature a employé pour produire de pareils effets. nous nous contenterons, ainsi que nous avons promis, de rendre compte de ce que nous avons vu et observé, et d'engager ceux qui auront la facilité de faire des remarques analogues de constater leurs observations en indiquant toujours les lieux fidèlement, ainsi que nous le faisions pour la suisse.» here the experience of our naturalist amounts to this, that, in those operations by which the solid land is wasted, and the hard materials worn by attrition and transported, it is not always evident from whence had come every particular body of stone or mineral which had travelled by means of water; nor the particular route which, in descending from a higher to a lower place, the protruded body had been made to take, although, in general, these facts may be discovered without much difficulty. now, this state of things is no other than the natural consequence of the great wasting of the surface and solid parts of our land, and the unequal degradation of this surface, by which means the shape of the earth is so changed, that it would often be impossible, from the present state, to judge of the course in which many bodies had been travelled by water. m. de saussure has described a very curious appearance of this kind: it is the finding the travelled materials of mont blanc, or fragments detached from the summit and centre of the alps, in such places as give reason to conclude that they had passed through certain openings between the mountains of the jura. this is a thing which he thinks could not happen according to the ordinary course of nature; he therefore ascribes this appearance to some vast _debacle_, or general flood, which had with great impetuosity transported all at once those heavy bodies, in the direction of that great current, through the defiles of the alps, or the openings of those mountains. in giving this beautiful example of the wasting and transporting operations of this earth, this naturalist overlooks the principles which i would wish to inculcate; and he considers the surface of the earth, in its present state, as being the same with that which had subsisted while those stones had been transported. now, upon that supposition, the appearances are inexplicable; for, how transport those materials, for example, across the lake of geneva? but there is no occasion to have recourse to any extraordinary cause for this explanation; it must appear that all the intervening hollows, plains, and valleys, had been worn away by means of the natural operations of the surface; consequently, that, in a former period of time, there had been a practicable course in a gradual declivity from the alps to the place where those granite masses are found deposited. in that case, it will be allowed that there are natural means for the transportation of those granite masses from the top of the alps, by means of water and ice adhering to those masses of stone, at the same time perhaps that there were certain summits of mountains which interrupted this communication, such as the jura, etc. through the openings of which ridges they had passed. in this case of blocks of alpine stones upon the jura, the question is concerning the transportation of those stones; but, in other cases, the question may be how those blocks were formed. that many such blocks of stone are formed by the decay of the rock around them, is clearly proved by the observations of m. hassenfratz, published in the _annales de chimie_, october . he has particularly mentioned a place on the road from saint-flour to montpellier, where an amazing collection of these blocks of granite is to be seen. it is here particularly that he observes these blocks to be the more durable parts which remain after the rock around them is decayed and washed away. the proof is satisfactory; the operation is important to the present theory; and therefore i shall give it in his own words. «tous les blocs de granit dur dégagés et sortis entièrement des masses qui forment les montagnes, posent immédiatement sur le granit friable ou sur d'autres blocs durs qui eux-mêmes sont sur le granit friable. «quoique la plupart des blocs de granit dur, que l'on observe sur toute l'étendue de ce terrain granitique, soient entièrement sortis et dégagés de la masse de pierre qui forme la montagne, on en rencontre cependant qui ne sont pas encore tout-à-fait dégagés. et c'est ici l'observation essentielle qui conduit directement à l'explication du phénomène de l'arrangement, de l'entassement, et de _l'amoncellement_ des blocs d'une manière simple et absolue. «on voit sur la surface du terrain des portions de blocs durs qui semblent sortir peu à peu, et se dégager de la masse de granit friable; celui-ci se décompose et se réduit en poussière tout autour de cette masse dure que les causes de décomposition du granit friable semblent respecter. «quelques-uns de ces blocs durs, sortans de la montagne granitique, sont déjà considérable; on distingue qu'ils n'y tiennent plus que par une très-petite partie; d'autres commencent à paroître se dégager, ils ne _saillent_, ils ne sortent encore que de quelque pieds, et même de quelques pouces. enfin, en examinant soigneusement et attentivement toute la surface de ce terrain granitique, on apperçoit tous les intermédiaires entre un bloc de granit dur contenu et enchassé dans la masse totale du granit friable et un bloc entièrement dégagé. «ces observations, suivies avec attention, ne laissent aucun doute que les blocs de granit que l'on observe sur toute l'étendue de ce terrain granitique, n'aient fait autrefois partie d'une couche considérable de granit décomposable qui couvroit ces montagnes et exhaussoit leur sol; que cette couche, dont il semble impossible d'apprécier la hauteur, malgré les blocs considérable qui restent et qui attestent son existence, a été décomposée par l'air et l'intempérie des saisons; que la poussière, le sable résultans de cette décomposition, ont été entraînés par les eaux, et déposés à divers points de la surface de la globe; et que ces blocs ont été peu-à-peu dégagés de la couche, ainsi qu'il s'en dégage encore tous les jours.» to enable the reader to form a notion of what these blocks are, i shall farther give what our author has said in describing this place where they are found. «c'est après avoir quitté le terrain volcanique, c'est dans le terrain granitique que j'ai trouvé des blocs énormes de granit, qui ont fixé mon attention. «toute l'étendue du terrain granitique que j'ai traversée, se trouve presque couverte de ces masses; les uns sur les sommets des montagnes les plus élevées, les autres sur la pente et dans les vallées. plusieurs de ces masses sont arrangées les uns sur les autres avec un art inimitable, les autres sont isolées et éparses. «peu de ces masses m'ont présenté un spectacle plus beau et plus imposant que celles que l'on rencontre à heures de marche de s. flour, à une petite demi heure avant d'arriver à la garde. «là, sur le sommet d'une montagne, est un amas considérable de blocs de granit, étonnans par leur volume et leur nombre. la grande route passe à travers, et circule autour de ces masses que les constructeurs des chemins n'ont pas osé attaquer. «le voyageur est pénétré d'admiration en voyant l'ordre et l'arrangement symétrique de ces blocs monstrueux par leur masse, et qu'il ne cesse d'observer en suivant la trace tortueuse du chemin qui les contourne. «quelques-uns de ces blocs sont posés purement et simplement les uns sur les autres, et forment une colonne isolée; le plus gros sert de base, et les autres, graduellement plus petits, son posés dessus. on voit jusqu'à trois de ces blocs immédiatement l'un sur l'autre. «d'autres fois, le bloc qui sert de base est beaucoup plus petit que celui qui le couvre immédiatement; et s'arrangement de ces deux blocs présente l'aspect d'un champignon. «plus souvent plusieurs blocs séparés les uns des autres, forment la base, et un ou plusieurs blocs sont posés immédiatement dessus, sans ordre constant, tantôt inclinés, mais toujours d'une manière stable et fixe, propre à resister aux plus grands efforts. «enfin, par fois, des masses plus petites placées entre les grosses, semblent assurer la situation fixe de l'ensemble des blocs; mais ces rencontres sont fort rares.» here is a distinct view of this part of nature; a view in which the present state of things plainly indicates what has passed, without our being obliged to raise our imagination to so high a pitch as is sometimes required, when we take the mountains themselves, instead of these blocks, as steps of the investigation. here is a view, therefore, that must convince the most scrupulous, or jealous with regard to the admitting of theory, first, that those mountains had been much higher; secondly, that they had been degraded in their present place; thirdly, that this continent has subsisted in its present place for a very long space of time, during the slow progress of those imperceptible operations; and, lastly, that much of the solid parts of this earth has been thus travelled by the waters to the sea, after serving the purpose of soil upon the surface of the land. but though m. hassenfratz has thus given us a most satisfactory view of the natural history of those blocks of stone which are now upon or near their native place, this will not explain other appearances of the same kind, where such blocks are found at great distances from their native places, in situations where the means of their transportation is not to be immediately perceived, such as those resting upon the jura and saleve, and where blocks of different kinds of stone are collected together. these last examples are the records of something still more distant in the natural history of this earth; and they give us a more extensive view of those operations by which the surface of this earth is continually changing. it is, however, extremely interesting to this theory of the earth, to have so distinctly ascertained some of those first steps by which we are to ascend in taking the more distant prospect; and these observations of m. hassenfratz answer this end most completely. thus all the appearances upon the surface of this earth tend to show that there is no part of that surface to be acknowledged as in its original state, that is to say, the state in which it had come immediately from the mineral operations of the globe; but that, every where, the effects of other operations are to be perceived in the present state of things. the reason of this will be evident, when we consider, that the operations of the mineral kingdom have properly in view to consolidate the loose materials which had been deposited and amassed at the bottom of the sea, as well as to raise above the level of the ocean the solid land thus formed. but the fertility of the earth, for which those operations were performed, and the growth of plants, for which the surface of the earth is widely adapted, require a soil; now the natural, the proper soil for plants, is formed from the destruction of the solid parts. accordingly, we find the surface of this earth, below the travelled soil, to consist of the hard and solid parts, always broken and imperfect where they are contiguous with the soil; and we find the soil always composed of materials arising from the ruin and destruction of the solid parts. chap. vi. _a view of the economy of nature, and necessity of wasting the surface of the earth, in serving the purposes of this world_. there is not perhaps one circumstance, in the constitution of this terraqueous globe, more necessary to the present theory, than to see clearly that the solid land must be destroyed, in undergoing the operations which are natural to the surface of the earth, and in serving the purposes which are necessary in the system of this living world. for, all the land of the present earth being a certain composition of materials, perfectly similar to such as would result from the gradual destruction of a continent in the operations of the inhabited world, this composition of our land could not be explained without having recourse to preternatural means, were there not in the constitution of this earth an active cause necessarily, in the course of time, destroying continents. it is therefore of great importance to this theory, to show, that the land is naturally wasted, though with the utmost economy; and that the continents of this earth must be in time destroyed. it is of importance to the happiness of man, to find consummate wisdom in the constitution of this earth, by which things are so contrived that nothing is wanting, in the bountiful provision of nature, for the pleasure and propagation of created beings; more particularly of those who live in order to know their happiness, and who know their happiness on purpose to see the bountiful source from whence it flows. we are to conceive the continent of the earth, when first produced above the surface of the ocean, to be in general consolidated, with regard to its structure, by the same mineral operations which are necessarily employed in raising it from its primary situation at the bottom of the sea, to that in which we now inhabit it. we are now to consider the purpose of this mineral body, exposed to the influences of the atmosphere, that so we may see the intention of its solid composition, as well as that of its resolution, or natural solubility when thus exposed; and we are to trace the ultimate effects of this order of action in the economy of the globe, that so we may perceive the wisdom of nature perpetuating the system of a living world in an endless succession, of changing perishable forms. the purpose of the land of this earth, in being placed above the sea and immersed in the atmosphere, is to sustain a system of plants and animals. but; for the purpose of plants; there is required a soil; and, as there is in the vegetable system a vast variety of plants with different habits or natural constitutions, there is also required a diversity of soils, in which those vegetable bodies are to be made to live and prosper. from the bare rock exposed to the sun and wind, to the tender mud immersed in water, there is a series to be observed; and in every stage or step of this gradation, there are plants adapted to those various soils or situations. therefore nothing short of that diversity of soils and situations, which we find upon the surface of the earth, could fulfill the purpose of nature, in producing a system of vegetables endued with such a diversity of forms and habits. the soil or surface of this earth is no more properly contrived for the life and sustenance of plants, than are those plants for that diversity of animals, which will thus appear to be the peculiar care of nature in forming a world. scarce a plant perhaps that has not its peculiar animal which feeds upon its various productions; scarce an animal that has not its peculiar tribe of plants on which the economy of its life, its pleasure, or its prosperity must depend. if we shall suppose the continent of our earth to be a solid rock, on which the rain might fall, and the wind and waves might dash perpetually, without impairing its mass or changing its constitution, what an imperfect world would we have! how ill adapted to the preservation of animal and vegetable life! but the opposite extreme would equally frustrate the intention of nature, in producing bounteously for the various demands of that multiplicity of species which the author of this world has thought proper to produce. for if, instead of a solid rock, we shall suppose a continent composed of either dry sand or watery mud, without solidity or stability, how imperfect still would be that world for the purpose of sustaining lofty trees and affording fruitful soils! we have now mentioned the two extreme states of things; but the constitution of this earth is no other than an indefinite number of soils and situations, placed between those two extremes, and graduating from the one extreme, in which some species of animals and plants delight in finding their prosperity, to the other, in which another species, which would perish in the first, are made to grow luxuriantly. that is to say, the surface of this earth, which is so widely adapted to the purpose of an extensive system of vegetating bodies and breathing animals, must consist of a gradation from solid rock to tender earth, from watery soil to dry situations; all this is requisite, and nothing short of this can fulfil the purpose of that world which we actually see. we have been representing this continent of our earth as coming out of the ocean a solid mass, which surely it is in general, or in a great degree; but we find the surface of this body at present in a very different state; and now it will be proper to take a view of this change from solid rock to fertile soil. upon this occasion i shall give the description of nature from the writings of a philosopher who has particularly studied this subject. it is true that m. de luc, who furnishes the description, draws, from this process of nature, an argument for the perpetual duration or stability of mountains; and this is the very opposite of that view which i have taken of the subject; but as, in this operation of nature producing plants on stones, he allows the surface of the solid stone to be changed into earth and vegetables, it is indifferent to the present theory how he shall employ this earth and vegetable substance, provided it be acknowledged that there is a change from the solid state of rock to the loose or tender nature of an earth, from the state of a body immovable by the floods and impenetrable to the roots of plants, to one in which some part of the body may be penetrated and removed. [ ]«les pluies et les rosées forment partout où elles séjournent, des dépôts qui sont la première source de toute _végétation_. ces dépôts sont toujours mêlés des semences des _mousses_, que l'air charie continuellement, et auxquelles se joignent bientôt les semences presque aussi abondantes des _gramens_, qui sont l'herbe dominante de nos prairies. ainsi partout où la pluie a formé quelque petit dépôt, il croît de la mousse ou des _gramens_. ceux-ci demandent un peu plus de _terre végétale_ pour croître, ils germent, et se conservent principalement dans les intervalles et les creux des pierres: mais la _mousse_ croît bientôt sur la surface la plus unie. il n'est aucune pierre long-temps exposée à l'air, qui soit parfaitement polie; l'action de l'air, du soleil, des eaux, des gelées, detruiroit ce poli quand il existeroit. le moindre creux alors reçoit un dépôt de la pluie, et nourrit un brin de _mousse,_ ces brins poussent des racines; et de nouveaux jets autour d'eux, qui contribuent à arrêter l'eau de la pluie et de la rosée, et par ce moyen à arrêter les dépôts nourriciers.» [footnote : histoire de la terre, tom. . page .] «quand la mousse a multiplié ses filets, les dépôts s'augmentent plus rapidement encore; les brins de la _mousse,_ en séchant et pourrissant, en forment eux-mêmes; car leur substance n'étoit que ces mêmes dépôts façonnés: d'autres semences charriées par l'air, qui au-paravant glissaient sur les pierres, parce que rien ne les retenoit, tombent dans le fond de la _mousse_, et y trouvent l'humidité nécessaire pour produire leurs premières racines: celles-ci s'entrelassent dans la _mousse_, où elles se conservent à l'abri du soleil, et sont alors autant de petites bouches qui pompent les sucs, que l'air, les pluies, et les rosées y déposent. ces premières plantes sont foibles, quelque fois même elles ne parviennent pas à leur perfection: mais elles ont contribué à fixer la _terre végétable_. en séchant et se décomposant, elles se transforment en cette _terre_, qui tombe au fond de la _mousse_, et qui prépare ainsi de la nourriture pour de nouvelles plantes qui alors prospèrent et fructifient. «nous connoissons peu encore ce que c'est que cette _terre végétable_, ce dépôt des pluies ou en général de l'air. cependant, en rassemblant les phénomènes, on peut conjecturer, que la plupart des corps terrestres sont susceptibles d'être changés en cette substance, et qu'il ne s'agit pour cette transformation que de les décomposer. j'entends par là une telle division de leurs parties, que devenant presque des élémens, elles puissent être intimement mêlées à l'eau, et pompées avec elle par les tuyaux capillaires des plantes. en un mot, il semble suffisant qu'une matière puisse entrer en circulation dans les végétaux, pour qu'elle serve à en développer le tissu, et qu'elle y prenne la figure et les qualités que chacun de ces laboratoires est propres à produire. «nous pouvons accélérer de bien des manières la transformation des matières terrestres en _terre végétable_. la fermentation, la calcination, une plus grande exposition à l'air, différens mélanges, rendent propres à la végétation, des matières qui ne l'étoient par elles-mêmes: voila ce que peuvent nos soins. mais l'air travaille sans cesse et en mille manières. son simple frottement sur tous les corps, en enlève des particules si atténuées que nous ne les reconnoissons plus. la _poussière_ de nos appartemens en est peut-être un exemple. de quelque nature que soient les corps dont elle se détache, c'est une poudre grisâtre qui semble être partout la même. la formation de la _terre végétable_ a probablement quelque rapport à celle-là. toute la surface de la terre, les rocs les plus durs, les sables et les graviers les plus arides, les métaux même, éprouvent l'action _rongeante_ de l'air et leurs particules atténuées, décomposées, recomposées de mille manières, sont probablement la source principal de la végétation. _l'air_ lui-même ainsi que _l'eau_, s'y combinent: beaucoup d'observations et d'expériences nous prouvent que ces deux fluides fournissent leur propre substance aux parties solides des végétaux, et par conséquent à la _terre végétable_ qui les produit et qu'ils déposent. quantité de plantes se nourrissent de _l'eau_ seule, et nous laissant cependant en se séchant, un résidu de matière solide permanente. _l'air_ aussi se _fixe_ dans les corps terrestres, il fait partie de leur substance solide; les chimistes savent de plus en plus, et le _fixer_, et lui redonner son élasticité primitive, par divers procédés: et avant la multitude d'expériences qui se sont de nos jours sur cet objet intéressant de la physique, le dr. hales avoit montré, que les végétaux renferment une très-grande quantité _d'air_, qui s'y trouve sans ressort et comme matière constituante. «voila donc probablement les sources où la nature puise peu à peu la _terre végétable_ dont elle recouvre la surface de nos continens. ce sont les particules, peut-être, de tous les corps tant solides que fluides, extraites ou fixées par des procédés qui les rapprochent de leurs premiers élémens, et leur font prendre à nos yeux une même apparence. ces particules sont ainsi rendues propres à circuler dans les semences des plantes, à en étendre le tissu à y prendre toutes les propriétés qui caractérisent chaque espéce, et à les conserver tant que la plante existe. ces mêmes particules, après la destruction des plantes, prennent le caractère général de _terre végétable_, c'est-à-dire de provision toute faite pour la végétation. «les plus petits recoins des montagnes, qui peuvent arrêter l'eau de la pluie, sont certainement fertilisés; ce ne sont pas seulement les grandes surfaces plates, ni les pentes; ce sont même les faces escarpées des rochers les plus durs. s'il s'y fait quelque crevasse, un arbre s'y établit bientôt; et souvent il contribue, par l'accroissement de ses racines, à accélérer la chute du lambeau de rocher qui l'avoit reçu. s'il y a quelque petite terrasse, ou seulement quelque partie saillante grande comme la main, elle est bientôt gazonnée. les plus petites sinuosités se peuplent de plantes; et les surfaces les plus unies, celles mêmes qui sont tournées vers la bas, reçoivent au moins quelqu'une de ces _mousses_ plates, nommés _lichen_ par les botanistes, qui ne font en apparence que passer une couleur sur la pierre. mais cette couche est écaillée, et elle loge bientôt de petites plantes dans ses replis; de celles qui veulent l'ardeur du soleil, si le rocher est au midi, ou la fraîcheur de l'ombre, s'il est au nord: c'est sur ces rochers en un mot, qui paroissent nues aux spectateurs ordinaires, que se trouve la plus grande variété de ces petites plantes, qui font les délices des botanistes, et l'une des sources les plus abondantes où la médicine puise les secours réels qu'elle fournit à l'humanité. «quelle richesse dans les ressources de la nature! la pesanteur n'est pas plus prête à entraîner les pierres qui se détachent des montagnes, que l'air à fournir de semences celles qui se fixent: et dès qu'une fois elles sont recouvertes de plantes, elles sont certainement fixées pour toujours, du moins contre les injures de l'air. le fait même nous l'annonce. si ces ravins ou ces terreins quelconques, tendoient encore à rouler ou à se dégrader, en un mot à se detruire de quelque manière que ce fut, ils ne le recouvriroient, ni de _mousses_ ni d'aucune autre plante. la première végétation est due à quelque dépôt de _terre végétable_; et les pluies ou l'air n'en forment que lentement; le moindre mouvement la détruite. le terrein est donc bien certainement fixe quand il se recouvre de plantes; et s'il s'y accumule de la _terre végétable_, c'est un signe bien evident que rien ne l'attaque plus: car elle seroit la première emportée si quelque cause extérieure tendoit a detruire le sol qui la porte.» the doctrine here laid down by our author consists in this; first, that there is a genus of plants calculated to grow upon rocks or stones; those hard bodies then decay, in decomposing themselves, and affording sustenance to the plants which they sustain. secondly, that by this dissolution of those rocks, and the accumulation of those vegetable bodies, there is soil prepared for the nurture and propagation of another genus of plants, by which the surface of the earth, naturally barren, is to be fertilised. it is also in this natural progress of things that the solid parts of the globe come to be wasted in the operations of the surface, and that lofty rocks are levelled, in always tending to bring the uneven surface of the earth to a slope of vegetating or fertile soil. here we are to distinguish carefully between the facts described by this author, who has seen so much of nature, and the conclusion which he would draw from his principles. the surface of most stones are dissolved, or corroded by the air and moisture. this gives lodgement to the roots of plants, which grow, die, and decay; and these are carried away with the earthy parts of the solid stone, in order to form a vegetable soil for larger plants, growing upon some bottom or resting place to which that earth is carried. here is so far the purpose of rocks, to sustain a genus of plants which are contrived to live upon that soil; and here is so far a purpose for certain plants, in decomposing rocks to form a soil for other plants which have been made upon a larger scale, and are adapted to the use of man, the ultimate in the view of nature. our author concludes thus: (p. .) «le tems ne fera qu'augmenter l'épaisseur de la couche de _terre végétable_ qui couvre les montagnes, et qui les garantit ainsi de plus en plus de cette destruction à laquelle on les croit exposés: les pluies en un mot, au lieu de les dégrader comme on se l'imagine y accumuleront leurs dépôts. tel est l'agent simple qu'employe si admirablement le createur pour la conservation de son ouvrage.» such, indeed, is the admirable contrivance of the system, that, in the works of nature, nothing shall be destroyed more than is necessary for the preservation of the whole. but, that the whole is preserved by the necessary destruction of every individual body, and the change of every part which comes within the examination of our senses, is sufficiently evident to require no farther illustration in this place, where we are contemplating the destruction of the strongest things, by means the most effectual, though really slow, and apparently most feeble. in his th letter, this author describes the progress of nature, in bringing precipitous rocks to that slope and covering of soil which is to maintain plants of every kind, and to establish woods. (p. .) «j'ai l'honneur d'exposer à v.m. les causes qui garantissent de destruction extérieure les terreins sur lesquels la _pesanteur_ ne peut plus agir que pour les consolider. mais ce n'est pas ainsi que sont actuellement la plupart de nos montagnes; il en est peu qui soyent déjà parvenus à cet état permanent. tout roc nud est attaqué par l'air et les météores, et il tend à se détruire quelle que soit sa dureté. mais ce seroit peu que cette destruction extérieure; elle pourroit même cesser enfin totalement par l'effet seul des _mousses_, s'il n'y avoit pas des causes plus puissantes qui pendant quelque tems agissent dans l'intérieur. «il n'est presque point de rocher qui offre à l'air une seule masse compacte; ils sont ou crevassés, ou formés par couches; et l'eau s'insinue toujours dans ces fentes. quand cette eau vient à se geler, elle agit comme un coin pour écarter les pièces entre lesquelles elle se trouve. v.m. seroit étonnée de la grandeur des masses que cette cause peut mouvoir: elle agit exactement comme la poudre à canon dans les mines; détachant toutes les pièces extérieures qui commencent à se séparer, et en découvrant ainsi de nouvelles. chaque hiver renouvelle donc la surface de certains rochers, ou facilite l'ouvrage pour les hivers suivans. plusieurs autres causes agissent encore pour séparer les rochers déjà crevassés, qui se trouvent à l'extérieur des faces escarpées. le petit moellon qui s'y accumule, les dépôts des pluies, les plantes qui y croissent, les alternatives de l'humidité et de la sécheresse, les vicissitudes de la chaleur, les vents même, sont autant de causes continuellement agissantes quand la _pesanteur_ les seconde. les rochers escarpés se détruisent donc par de continuels éboulemens. «mais toutes ces matières qui tombent, ne sont pas perdues pour les montagnes; il s'en perd même bien peu. elles s'arrêtent au pied des rochers dont elles sont successivement détachées; et là elles s'entassent, s'élevant en forme de _talus_ contre ces rochers eux-mêmes.» if the solid body of the alps, the most consolidated masses of our land, is thus reduced to the state of soil upon the surface of the earth contrived for the use of plants, _a fortiori_, softer bodies, less elevated and less consolidated masses, will be considered as easily arriving at the purpose for which the surface of the earth has been intended. we only wish now to see the ultimate effect that necessarily follows from this progress of things; and how, in this course of nature, the land must end, however long protracted shall be the duration of this body, and however much economy may be perceived in this gradual waste of land;--a waste which by no means is so slow as not to be perceived by men reasoning in science; although scientific men, either reasoning for the purpose of a system which they had devised, or, deceived by the apparent state of things which truly change, may not acknowledge the necessary consequence of what they had perceived. let us now suppose all the solid mass of land, contained in our continent, to be transformed into soil and vegetable earth, it must be evident that no covering of plants, or interlacing of vegetable fibres, could protect this mass of loose or incoherent materials from the ravages of floods, so long as rivers flowed, nor from being swallowed by the ocean, so long as there were winds and tides. from the border of the land upon the shore, to the middle of the ocean, there is either at present an equable declivity at the bottom of the sea, or every thing tends to form this declivity, in gradually moving bodies along this bottom. but, however gradual the declivity of the bottom, or however slow the progress of loose materials from the shore towards the deepest bottom of the sea, so long as there are moving powers for those materials, they must have a progress to that end; the law of gravitation, always active, must prevail, and sooner or later the moving sea must swallow up the land. but, along the borders of our continent, and in the courses of our rivers, there are rocks; these must be surmounted or destroyed, before the parts which they protect can be delivered up to the influence of those moving powers which tend to form a level; and we may be assured that those bulwarks waste. the bare inspection of our rocky coasts and rivers will satisfy the enlightened observator of this truth; and to endeavour to prove this to a person who has not principles by which to reason upon the subject, or to one who has false principles, by which he would create perpetual stability to decaying things, would be but labour lost. in proportion as the solid bulwark is destroyed, so is the soil which had been protected by it; and, in proportion as the solid parts of the mass of land are exposed to the influences of the atmosphere and water, by the ablution of the soil, more soil is prepared for the growth of plants, and more earth is detached from the solid rock, to form deep soils upon the surface of the earth, and to establish fertile countries at the mouths of rivers, even in making encroachment on the space allotted for the sea. but this production of land, in augmentation of our coasts, is only made by the destruction of the higher country. while, therefore, we allow that there is any augmentation made to the coast, or any earthy matter travelling in our rivers, the land above the coast cannot be stable, nor the constitution of our earth fixed in a state which has no tendency to be removed. m. de luc, in his histoire de la terre, would make the mountains last for ever, after they have come to a certain slope. he sums up his reasoning upon this subject in these words: «l'adoucissement des pentes arrête d'abord l'effet de ces deux grandes causes causes de destruction de montagnes, la _pesanteur_ et les _eaux_: la végétation ensuite arrêté l'effet de toutes les petites cause.» if all the great and little causes of demolition are arrested by the slope of mountains and the growth of plants, the surface of the earth might then remain without any farther change; and this would be a fact in opposition to the present theory, which represents the surface of the earth as constantly tending to decay, for the purpose of vegetation, and as being only preserved from a quick destruction by the solid rocks protecting, from the ravages of the floods and sea, the loose materials of the land. it will therefore be proper to show, that this author's argument does not go to prove his proposition in the terms which he has given it, which is, that those sloped mountains are to last for ever, but only that these causes, which he has so well described, make the destruction of the mountains become more slow[ ]. [footnote : this also would appear to be a part of that wise system of nature, in which nothing is done in vain, and in which every thing tends to accomplish the end with the greatest marks of economy and benevolence. had it been otherwise, and the demolishing powers of the land increased, in a growing rate with the diminution of the height, the changes of this earth and renovation of our continent, in which occasionally animal life must suffer, would necessarily require to be often repeated; and, in that case, chaos and confusion would seem to be introduced into that system which at present appears to be established with such order and economy that man suspects not any change; it requires the views of scientific men to perceive that things are not at present such as they were created; it requires all the observation of a natural philosopher to know that in this earth there had been change, although it is not every natural philosopher that observes the benevolence accompanying this constitution of things which must subsist in change.] the slope which our author gives to his mountains, in order to secure them from the ravages of time, is that which, according to his own reasoning, renders them fertile and proper for the culture of man; but fertile soil yields always something to the floods to carry away; and, while any thing is carried from the soil, the land must waste, although it may not then waste at the rate of those within the valleys of the alps. according to the doctrine of this author, our mountains of tweeddale and tiviotdale, being all covered with vegetation, are arrived at that period in the course of things when they should be permanent. but is it really so? do they never waste? look at the rivers in a flood;--if these run clear, this philosopher has reasoned right, and i have lost my argument. our clearest streams run muddy in a flood. the great causes, therefore, for the degradation of mountains never stop as long as there is water to run; although, as the heights of mountains diminish, the progress of their diminution may be more and more retarded. let us now see how far our author has reasoned justly with regard to vegetation, which, he says, stops the effects of all the little causes of destruction; this is the more necessary, as, in the present theory, it is the little causes, long continued, which are considered as bringing about the greatest changes of the earth. along the courses of our rivers there are plains between the mountains of greater or lesser extent; these are almost always fertile, and generally cultivated when large; when small, they are in pasture. the origin of these fertile soils, and their perpetual change, is to be described with a view to show, that vegetation, although most powerful in stopping the ravages of water, and for accumulating soil retained by this means, does it only for a time; after which the soil is again abandoned to the ravages of the running water, when no more protected by the vegetation. let us suppose the river running upon the one side of the haugh (which is the name we gave those little fertile plains) and close by the side of the mountain. in this case the bed of the river is deepest at the side of the mountain, which it undermines, leaving a falling _(un éboulement)_ on that side; on the other side, the river shelves gradually from the plain, and leaves soil in its bottom or stony bed upon the side of the haugh, in proportion as it makes advances in carrying away the bank at the bottom of the sloping mountain. the part which vegetation takes in this operation is now to be considered. when the river has enlarged its bed by preying upon one side, whether of the mountain or the haugh, the water only covers it in a flood; at other times, it leaves it dry. here, among the rocks and stones, the feeds of plants, left by the water or blown by the wind, spring up and grow; and, in little floods, some sand and mud is left among those plants; this encourages the growth of other plants, which more and more retain the fertile spoils of the river in its floods. at last, this bed of the river is covered perfectly with plants, which having retained plenty of fertile soil, although still rooted among the stones, opposes to the river a resistance which its greatest velocity is not able to overcome. in this state, the haugh is always deepening or increasing its soil, and has its surface heightened. at last, when this soil becomes so high as only to be flooded now and then, it becomes most fertile, as the heavier parts are carried in the bed of the river, and the lighter soil deposited upon the plain. the operations of the river, upon the plain, thus increase at the same time the height and fertility of the haugh. but this operation, of accumulated soil upon the stony bottom, has a period, at which time the river must return again upon its steps, and sweep away the haugh which it had formed. this is the natural course of things; and it happens necessarily from the deepening of the soil. let us then examine this operation. when no more soil is left upon the stony bottom than is sufficient for the covering of the ground, and rooting of plants which are also fixed in the solid ground or bottom of the soil, the water is not able to carry away the plants; and these plants protect the surface of loose soil. when again there is a depth of soil accumulated upon the haugh, the surface only is protected by the vegetable covering. but what avails it to the soil to be protected from above, when undermined by the enemy! the vegetable roots now no longer reaching to the bottom where solidity is found, the tender soil below is easily washed away by the continued efforts of the stream; and the unsupported meadow, with the impregnable texture of its leaves, its roots, and its fibres, falls ruinously into the river, and is born away in triumph by the flood. the water thus reclaims its long deserted bed,--only in order to pass from it again, and circulate or meander from hill to hill in varying perpetually its course. now this progress of the river, or this changing of its bed, is determined by the strong resistance of the new made haugh, humbly standing firm in the protection of its vegetation, while the elevated surface of the older haugh, deserted by the inferior soil which it had ceased to protect, falls a victim to its exalted state, and passes away to aggrandize another. this is the fate of haughs or plains erected by the operations of a river, and again destroyed in the natural course of things, or in the very continuation of that active cause by which they had been formed. the water is constantly carrying the moveable soil from the higher to the lower place; vegetation often disputes the possession of these spoils of ruined mountains for a while; but, in the end, this vegetable protector, not only delivers up to the destroying cause the mineral soil which it had preserved, but, by its buoyancy in water, it facilitates the transportation of the stony parts to which this fibrous body is attached. over and over a thousand times may be repeated this alternate possession of the transferable soil, by moving water on the one part and by fixed vegetation on the other, but at last all must land upon the shore, whether the river tends. thus the mountain and the plain, the vegetable earth and the plants produced in that soil, must all return into the sea from whence either they themselves or their materials had come. in proportion as the mountains are diminished, the haugh or plain between them grows more wide, and also on a lower level; but, while there is a river running in a plain, and floods produced in the seasons of rain, there can be nothing stable in this constitution of things evidently founded upon change. the description now given is from the rivers of this country, where it is not unfrequent to see relicts of three or four different haughs which had occupied the same spot of ground upon different levels, consequently which had been formed and destroyed at different periods of time. but the same operation is transacted every where; it is seen upon the plains of indostan, as in the haughs of scotland; the ganges operates upon its banks, and is employed in changing its bed continually as well as the tweed[ ]. the great city of babylon was built upon the haugh of a river. what is become of that city? nothing remains,--even the place, on which it stood, is not known. [footnote : an account of the ganges and burrampooter rivers, by james rennel, esquire. philosophical transactions, .] chap. vii. _the same subject continued, in giving a view of the operations of air and water upon the surface of the land._ we have but to enlarge our thoughts with regard to things past by attending to what we see at present, and we shall understand many things which to a more contracted view appear to be in nature insulated or without a proper cause; such are those great blocks of granite so foreign to the place on which they stand, and so large as to seem to have been transported by some power unnatural to the place from whence they came. we have but to consider the surface of this earth as having been upon a higher level; as having been every where the beds of rivers, which had moved the matter of strata and fragments of rocks, now no more existing; and as thus disposed upon different planes, which are, like the haughs of rivers, changing in a continual succession, but changing upon a scale too slow to be perceived. m. de luc has given a picture which is very proper to assist our imagination in contemplating a more ancient state of this earth, although in this he has a very different end in view, and means to show that the world, which we inhabit at present, is of a recent date. it is in the d letter of his histoire de la terre, which i beg leave here to transcribe. «des montagnes basses (comme le _jura_, qui est bas comparativement aux alpes) sont bientôt fixées par ce moyen. il ne se fait presque qu'un seul _talus_ depuis leur sommet jusques dans les basses vallées, ou sur la plaine. aussi l'état de ces montagnes est-il déjà presqu'entièrement _fixé_: on y voit très peu de rochers nuds qui s'éboulent, excepté, auprès des _rivières_. c'est dans ces lieux-la que l'ouvrage tarde le plus à se finir. le bas des _talus_ est miné par l'eau; leur surface s'éboule donc, pour ainsi dire, sans cesse, et laisse à découvert les rochers des sommets, qui par la continuent aussi à _s'ébouler_. mais les vallées s'élargissent enfin; et les _talus_ s'éloignant ainsi des _rivières_, commencent à éprouver les influences du repos.» here nothing can be more positively described than the natural destruction of those mountains by the operation of the rivers which run between them; and this is from the authority of matter of fact, which, on all occasions, this author faithfully describes. at the same time, we are desired to believe, upon no better authority than the imagination of a person hurried on by system, that those mountains are absolutely to come to rest. i am aware of the danger to which a spirit of systematising leads; and i wish for nothing more than to have my theory strictly examined, in comparing it with nature. our author thus proceeds: «la vue seule de la chaine du _jura_ nous apprend donc ce que deviendroit enfin toutes les montagnes. dans la plus grande partie de son étendue, il ne souffre plus aucun changement ruineux: la _végétation_ le recouvre presque partout. les bas sont cultivés de toute sorte de manière suivant leur exposition; les sommets sont couverts de pelouses, qui forment les pâturages les plus precieux. cette gazonade s'étend aussi sur toutes les parties des pentes qui ne sont pas trop rapides, et le reste est couvert de bois. «j'ai parcouru fort souvent le pied de ces montagnes: leur état est presque partout tel que je viens d'avoir l'honneur de la descrire à v.m. j'ai sur-tout observé avec attention les lits des _torrens_ qui, en descendent pour se rendre dans les lacs de _geneva_, de _neufchâtel_ et de _bienne_, ainsi que dans l'aar et dans le rhin: et hormis ceux de ces _torrens_ qui viennent des gorges où les terrains sont encore escarpés, ils ne roulent plus que l'ancien gravier qu'ils out apporté autrefois. «mais il n'en est pas ainsi des _alpes_, des _pyrénées_, et des autres montagnes, qui, comme celles-là, sont beaucoup plus élevées, ou qui sans l'être davantage ont été livrées aux influences de l'air dans un désordre plus grand. dans ce genre de montagnes il reste encore à la _végétation_ de bien grandes conquêtes à faire. «ces montagnes ne sont pas telles que v.m. pourroit se les figurer naturellement; il faut y être monté pour s'en former une juste idée. ce sont des montagnes sur d'autres montagnes. de près on ne voit que les parties inférieures; de loin tout se confond; il faut donc être arrivé sur une des premières _terrasses_ pour voir les secondes; sur celles-ci pour les troisièmes; et ainsi de suite. «la plupart de ces _terrasses_ successives sont de grandes plaines, dominées par des rochers qui s'éboulent, et forment des _talus_. si dans la succession des siècles, les _éboulemens_ de ces bandes de rochers en amphithéâtre finissoient sans emporter les plaines qu'ils soutiennent, et que les _torrens_ eussent creusé leur lit pendant ce tems là à quelque distance des _talus_ tout seroit fini par cette première operation. mais il y a peu de hautes montagnes où les arrangemens soient si simples: souvent ces bandes empiètent les unes sur les autres en _s'éboulant_, et alors le repos est bien différé. «supposons que ces _terrasses_ soient étroites, et que leurs murs, c'est-à-dire les rochers qui les soutiennent, soient fort élevés. les _terrasses_ alors ne suffiront pas pour recevoir les _éboulemens_ qui doivent se faire sur elles car le dessus de chacune d'elles s'étrécit de plus en plus par la destruction du rocher qui la soutient. il pourra donc arriver que ce talus, s'étant étendu jusqu'au bord de la terrasse, se trouve reposer sur une base qui s'éboule encore; et même cela arrive très souvent; de sorte qu'à chaque rétrécissement de la base, le _talus_ lui-même s'éboule. ainsi deux _talus_, qui étoient peut-être déjà en pleine végétation par la lenteur des éboulemens des rochers qui les formoient, pourront être fort reculés à cet égard; le _talus_ supérieur, parce que la surface fertilisée glissera en bas; et le _talus_ inférieur, parce que la sienne sera ensevelie sous de nouveaux décombres. «les montagnes qui sont dans ce cas seront proportionnellement plus abaissées que les autres; parce que leurs _talus_ se confondant ainsi et devenant par là fort étendus demeureront longtemps à devenir solides. les eaux partant de fort haut, auront le tems de s'y rassembler et de devenir destructives vers le bas. au lieu que dans les montagnes où les terrasses subsisteront encore après que tous les rochers se seront _éboulés_, les eaux étant reçues par reprises, perdront beaucoup de leur rapidité. elles se rassembleront dans les enfoncemens des petites vallées supérieures, elles s'y formeront des lits qu'elles ne rongeront presque point; et la _végétation_ restera tranquille partout.» let us now consider the height of the _alps_, in general, to have been much greater than it is at present; and this is a supposition of which we have no reason to suspect the fallacy; for, the wasted summits of those mountains attest its truth. there would then have been immense valleys of ice sliding down in all directions towards the lower country, and carrying large blocks of granite to a great distance, where they would be variously deposited, and many of them remain an object of admiration to after ages, conjecturing from whence, or how they came. such are the great blocks of granite which now repose upon the hills of _saleve_. m. de saussure, who has examined them carefully, gives demonstration of the long time during which they have remained in their present place. the lime-stone bottom around being dissolved by the rain, while that which serves as the basis of those masses stands high above the rest of the rock, in having been protected from the rain. but no natural operation of the globe can explain the transportation of those bodies of stone, except the changed state of things arising from the degradation of the mountains. every thing, therefore, tends to show that the surface of the earth must wear; but m. de luc, although he allows the principles on which this reasoning is founded, labours to prove that those destructive causes will not operate in time. now, what would be the consequence of such a system?--that the source of vegetation upon the surface of the earth would cease at last, and perfect sterility be necessarily the effect of allowing no farther degradation to the surface of the earth; for, what is to supply the matter of plants? water, air, and light alone, will not suffice; there are necessarily required other elements which the earth alone affords. if, therefore, this world is to continue, as it has done, to form continents of calcareous strata at the bottom of the ocean, the animals which form these strata, with their _exuviae_, must be fed. but, on what can they be fed? not on water alone; the consequence of such a supposition would lead us to absurdity; nor can they be fed on any other element without the dissolution of land. according to my views of things, it is certain that those animals are ultimately fed on vegetable bodies; and it is equally certain, that plants require a soil on which they may not only fix their fibrous roots, but find their nourishment at least in part; for, that air, water, and the matter of light, also contribute, cannot be doubted. but if animals, which are to form the strata of the earth, are to be fed on plants, and these are to be nourished by the matter of this earth, the waste of vegetable matter upon the surface of the earth must be repaired; the exhausted soil must be transported from the surface of the land; and fertility must be restored by the gradual decay of solid parts, and by the successive removal of soil from stage to stage. what a reverie, therefore, is that idea, of bringing the earth to perfection by fixing the state of its vegetable surface! the description of those natural operations, which m. de luc has given with a view to establish the duration of the mountains, is founded upon nothing but their destruction. these beds of rivers, which, according to our author, are _hardly_ to be wasted any more, will not satisfy a philosopher, who requires to see no degree of wasting in a body which is to remain for ever, or continue without change. but, however untenable this supposition of a fixed state in the surface of this earth, the accuracy of the natural philosopher may still be observed in the absurdity of the proposition. «l'état des _montagnes_ sera _fixe_, partout où les _rivières_ seront arrivées au point de n'emporter pas plus de limon hors de leur enceinte, que l'air et les pluies n'y déposeront de _terre végétable_, et voila enfin quel sera le repos, l'état permanent de la surface de notre globe. car alors il y aura compensation entre les destructions et les réparations simultanées, et les montagnes sûrement ne s'abaisseront plus.» surely, if there is in the system of nature wisdom, we may look for compensation between the destroying and repairing operations of the globe. but why seek for this compensation in the _rest_ or immobility of things? why suppose perfection in the want of change? the summit of the alps was once the bottom of the sea; the existence of our land depended then upon the change of seas and continents. but has the earth already undergone so great changes, and is it not yet arrived at the period of its perfection? how can a philosopher, who is so much employed in contemplating the beauty of nature, the wisdom and goodness of providence, allow himself to entertain such mean ideas of the system as to suppose, that, in the indefinite succession of time past, there has not been perfection in the works of nature? every material being exists in motion, every immaterial being in action and in passion; rest exists not any where; nor is it found in any other way, except among the parts of space. surely it is contrary to every species of philosophy, whether ancient or modern, to found a system on the inutility of repose, or place perfection in the vacuity of rest, when every thing that truly exists, exists in motion; when every real information which we have is derived from a change; and when every excess in nature is compensated, not by rest, but by alternation. m. de luc allows the rivers to carry matter always to the sea; but then, at a certain period, this matter carried by the floods is to be compensated to the mountains by the vegetable earth received from the air and rains. here is a proposition which should be well considered, before it be admitted as a principle, which shall establish the perpetuity of these mountains, if it be true; or, if false, assure us of their future demolition. let us now examine it. if from air and rain there is produced earth which cannot afterwards be resolved by the operation of those elements, and thus again dissolved in the air and water of the land, then this author might have had some pretext, however insufficient, for alledging that it might be possible to compensate the loss of mineral substances, carried off the surface of the earth, by the production of this vegetable matter from the air and rain; but, when there is not sufficient reason to conclude that any substance, produced in vegetation, can resist the continued influences of the air and water, without being decomposed in its principles, and at last entirely dissolved in water, the cautious argument here employed by this author, for the permanency of mountains, must appear as groundless in its principle as it would be insufficient for his purpose, were it to be admitted; but this will require some discussion. that which preserves vegetable bodies so long from dissolution in water, is what may be called the inflammable or phlogistic composition of those bodies. this composition is quickly resolved in combustion; but it is no less surely resolved by the influences of the sun and atmosphere, only in a slower manner. therefore, to place the permanency of this earth, or any of its surface, upon a substance which in that situation necessarily decays, is to form a speculation inconsistent with the principles of natural philosophy[ ]. [footnote : it is from inadvertency to this fact in natural history, the consuming of vegetable substances exposed to the influences of the atmosphere, that m. de luc, in his _histoire de la terre_, has pretended to determine the past duration of the german heaths as not of a very high antiquity. he has measured the increase of the vegetable soil, an increase formed by the accumulation of the decayed heath; and, from the annual increase or deposits of vegetable matter on that surface, he has formed a calculation which he then applies to every period of this turfy augmentation, not considering that there may be definitive causes which increase with this growing soil, and which, increasing at a greater rate in proportion as the soil augments, may set a period to the further augmentation of that vegetable soil. such is fire in the burning of those parched heaths; such is the slower but constant and growing operation of the oxygenating atmosphere upon this turfy substance exposed to the air and moisture. this author has very well described the constant augmentation of this vegetable substance in the morasses of that country, as it also happens in those of our own; but there is a wide difference in those two cases of peat bog and healthy turf; the vegetable substance in the morass is under water, and therefore has its inflammable quality or combustible substance protected from the consuming operation of the vital or atmospheric air; the turfy soil, on the contrary, is exposed to this source of resolution in the other situation.] but even supposing that the degradation of mountains were to be suspended by the pretended compensation which is formed, by the rivers carrying mineral mud into the sea, and the air and rain producing vegetable earth; in what must this operation end? in carrying into the sea, to be deposited at its bottom, all the vegetable earth produced by the air and rain. but our cosmologist, in thus procuring an eternal station to his mountains, has not told us whether this transmutation of the air and rain be a finite operation, or one that is infinite; whether it be in other respects confident with the natural operations of the globe; and whether, to have the air and water of the globe converted into earth, would ultimately promote, or not, that perfection which he wishes to establish. here, therefore, in allowing to this philosophy all its suppositions, it would be necessary to make another compensation, in preserving mountains at the expense of air and rain; and, the waste of air and water, which are limited, would require to be repaired. it is not in our purpose here to treat of moral causes; but this author having endeavoured to fortify his system by observing, that the world certainly cannot be ancient, since men have not ceased as yet to quarrel and fight, (lettre .) it may be proper to observe, that the absolute rest of land, like the peace among mankind, will never happen till those things are changed in their nature and constitution, that is to say, until the matter of this globe shall be no more a living world, and man no more an animal that reasons from his proper knowledge, which is still imperfect. if man must learn to reason, as children learn to speak, he must reason erroneously before he reasons right; therefore, philosophers will differ in their opinions as long as there is any thing for man to learn. but this is right; for, how are false opinions to be corrected, except in being opposed by the opinions of other men? it is foolish, indeed, for men to quarrel and fight, because they differ in opinion. man quarrels properly, when he is angry; and anger perhaps is almost always ultimately founded upon erroneous opinion. but, in nature, there is no opinion; there is truth in every thing that is in nature; and in man alone is error. let us, therefore, in studying nature, learn to know the truth, and not indulge erroneous notions, by endeavouring to correct, in nature, that which perhaps is only wrong in our opinion. having shown that every thing, which is moveable upon the surface of the land, tends to the sea, however slowly in its pace, we are now to examine, what comes of those materials deposited within the regions of the waves, still however within the reach of man, and still subservient more immediately to that soil on which plants grow, and man may dwell. as, from the summit of the land, the natural tendency of moveable bodies is to fall into the water of the sea, so, from the borders of the land or coast, there being a declivity towards the deepest bottom of the sea, and there being currents in the waters of the ocean occasionally rendered more rapid on the shore, every moveable thing must tend to travel from the coast, and to proceed alone; the shelving bottom of the sea into the unfathomable deep, when they are beyond the reach of man or the possibility of returning to the shore. but it is not every where upon the coast that those materials are equally delivered; neither is it every where along the shore that the currents of the ocean are equally perceived, or operate with equal power in moving bodies along the shelving bottom of the sea. hence in some places deep water is found washing rocky coasts, where the waste of land is only to be perceived from what is visibly wanting in the continuity of those hard and solid bodies. in other places, again, the land appears to grow and to encroach upon the space which had been occupied by the sea; for here the materials of the land are so accumulated on the coast, that the bottom of the sea is filled up, and dry land is formed in the bafon of the sea, from those materials which the rivers had brought down upon the shore.[ ] [footnote : we are not however to estimate this operation, of forming soil by the muddy waters of a river depositing sediment, in the manner that m. de luc has endeavoured to calculate the short time elapsed in forming the marshlands of the elbe. this philosopher, with a view to show that the present earth has not subsisted long since the time it had appeared above the surface of the sea, has given an example of the marsh of _wisebhafen_ where the earth, wasted by inundation, was in a very little time replaced, and the soil heightened by the flowings of the elbe, and this he marks as a leading fact or principle, in calculating the past duration of our continents, of which he says, we are not to lose sight (tome , p. .) but here this philosopher does not seem to be aware, that he is calculating upon very false grounds, when he compares two things which are by no means alike, the natural operations of a river upon its banks, making and unmaking occasionally its haughs or level lands, that is to say, alternately making and destroying, and the artificial operations of man receiving the muddy water of a tide-way into the still water of a pond formed by his ramparts; yet, it is by this last operation that our author forms an estimate which he applies to the age of this earth, in calculating how long time might have been required for producing the marsh lands of the elbe. i would here ask if he can calculate what time it may have required to hollow out the bed of the elbe from its source to the sea; and to tell how often the marsh-lands, which he now sees cultivated, had been formed and destroyed by the river before they were cultivated in their present state; or if there is any security that they shall not again be taken away by the river, and again formed in the same place. if this is the case, that the river is constantly changing the fertile lands, which it forms by its inundation, what judgement are we to form by calculating the quantity of sediment in a certain measure of its muddy water.] holland affords the very best example of this fact. it is a low country formed in the sea. this low land is situated in the bottom of a deep bay, or upon the coast of a shallow sea, where more materials are brought by the great rivers from the land of germany than what the currents of the sea can carry out into the deep. here banks of sand are gathered together by streams and tides; this sand is blown in hillocks by the wind; and those sand hills are retained by the plants which have taken root and fixed those moving sands. behind that chain of hillocks, which line the sea shore, the waters of the rivers formed a lake, and the bottom of this lake had been gradually filled up or heightened by materials travelling in the rivers, and here finding rest. it grew up until it became a marsh; then man took possession of the soil; he has turned it to his own life; and, by artificial ramparts of his forming, preserves it in the present state, some parts above the level of the sea, others considerably below the ordinary rise of tides. m de luc, who has given a very scientific view of this country in his lettres physiques et morales, has there also furnished us with the following register of what had been found by sinking in that soil. it was at amsterdam at the year in making a well. «voici la désignation des matières qui furent trouvées en partant de la surface. pieds, mêlés _de sable tourbeux_, de fable _des dunes pur_ et _d'argile_ ou limon. .---de même _sable des dunes pur_, et _d'argile_ bleuâtre. .---du même _sable_ pur. pieds.--ou rien encore n'indiquoit la présence de la mer. .---de _sable marin_, et _de limon_, mêles l'un et l'autre de _coquilles_ dans plusieurs couches. pieds.--soit la plus grande profondeur, où s'est manifestée la _présence_ de la mer. .---_argille_ dure sans mélange de coquilles, soit que ce soit une couche _argilleuse continentale,_ ou les premiers dépôts des fleuves; ce qu'il est difficile de déterminer. pieds. .---sable mêlé de pierres; qui est enfin sûrement le _sol_ vierge continental. .---sable pur; continental encore; car j'ai remarqué partout dans la _geest_, que c'est dans la couche supérieure, à une petite profondeur que se trouvent les pierres; au-dessous le _sable_ est pur. pieds.--c'est à cette profondeur, ou dans la masse de ces deux dernières couches, que se trouva l'eau douce, et par conséquent le vrai _sol continental_.» the light that we have from this pit which has been made in the soil, according to my view of the subject, is this, that here is the depth of feet in travelled soil, and no solid bottom found at this distance from the surface or level of the sea. how far this depth may be from the bottom of these travelled materials is unknown; but this is certain, that all that depth, which has been sunk, had been filled up with those materials[ ]. [footnote : an interesting map for the use of natural history would be made by tracing the places (behind this country of loose or travelled soil) where the solid strata appear above the level of the sea. we should be thus able to form some notion of the quantity of materials which had been deposited in the water of this sea. but, though we might thus enlarge our views a little with regard to the transactions of time past, it would only be in a most imperfect manner that we would thus form a judgment; for, not knowing the quantity of sand and mud carried out by the currents from the german sea into the atlantic, we could only thus perceive a certain minimum, which is perhaps a little portion of the whole.] it will thus appear of what unstable materials is composed the land of that temporary country. it will also be evident, that, by removing the sand banks of this coast, the whole of this low country would be swallowed by the sea, notwithstanding every effort that the power of man could make. but it may be alledged, that those sand banks are increasing still with the alluvion of germany, instead of being in a decreasing state. i should also incline to believe that this is truly the case; but, though we may acknowledge the growth of land upon the coast of holland, we must deny that a stable country can be formed in the bed of the sea by such means. for, however increasing may be the sand in the german sea, and however great additions may be made of habitable country to the coast of holland, yet, as the islands of great britain and ireland are worn by attrition on the shores, and are wasted by being washed away into the ocean, the causes for the accumulation of sand in the german sea must cease in time, when, in this progress of things, the sand banks, on which depends the existence of holland, must diminish, and at last be swept away, in leaving the solid coast of germany to be again buffeted by the waves, as is at present the coasts of ireland, france, and spain. this reasoning is, indeed, very far removed from that which is commonly employed for the purpose of conducting human operations, or establishing the political system of a nation; it is not, however, the less interesting to man, in that it cannot direct him immediately in his worldly affairs; and it is the only way of reasoning that can be employed in order to enlighten man with a view of those operations which are not to be limited in time, and which are to be concluded as in the system of nature, a system which man contemplates with much pleasure, and studies with much profit. thus we have shown, that, from the top of the mountain to the shore of the sea, which are the two extremities of our land, every thing is in a state of change; the rock and solid strath dissolving, breaking, and decomposing, for the purpose of becoming soil; the soil travelling along the surface of the earth, in its way to the shore; and the shore wearing and wasting by the agitation of the sea, an agitation which is essential to the purposes of a living world. without those operations, which wear and waste the coast, there would not be wind and rain; and, without those operations which wear and waste the solid land, the surface of the earth would become sterile. but showers of rain and fertile soil are necessarily required in the system of this world; consequently, the dissolution of the rocks, and solid strata of the earth, and the gradual, flow, but sure destruction of the present land, are operations necessary in the system of this world; so far from being evils, they are wisely calculated, in the system of nature, for the general good. chap. viii. _the present form of the surface of the earth explained, with a view of the operation of time upon our land_. it is not to _common_ observation that it belongs to see the effects of time, and the operation of physical causes, in what is to be perceived upon the surface of this earth; the shepherd thinks the mountain, on which he feeds his flock, to have been always there, or since the beginning of things; the inhabitant of the valley cultivates the soil as his father had done, and thinks that this soil is coeval with the valley or the mountain. but the man of scientific observation, who looks into the chain of physical events connected with the present state of things, sees great changes that have been made, and foresees a different state that must follow in time, from the continued operation of that which actually is in nature. it is thus that enlightened natural history affords to philosophy principles, from whence the most important conclusions may be drawn. it is thus that a system may be perceived in that which, to common observation, seems to be nothing but the disorderly accident of things; a system in which wisdom and benevolence conduct the endless order of a changing world. what a comfort to man, for whom that system was contrived, as the only living being on this earth who can perceive it; what a comfort, i say, to think that the author of our existence has given such evident marks of his good-will towards man, in this progressive state of his understanding! what greater security can be desired for the continuance of our intellectual existence,--an existence which rises infinitely above that of the mere animal, conducted by reason for the purposes of life alone. the view of this interesting subject, which i had given in the first part, published in the transactions of the edinburgh royal society, has been seen by some men of science in a light which does not allow them, it would appear, to admit of the general principle which i would thereby endeavour to establish. some contend that the rivers do not travel the material of the decaying land;--why?--because they have not seen all those materials moved. others alledge, that stones and rocks may be formed upon the surface of the earth, instead of being there all in a state of decay. these are matters of fact which it is in the power of men who have proper observation to determine; it is my business to generalise those facts and observations, and to bring them in confirmation of a theory which is necessarily founded upon the decaying nature and perishing state of all that appears to us above the surface of the sea. nothing is more evident, than that the general effect of mineral operations is to consolidate that which had been in an incoherent state when formed at the bottom of the sea, and thus to produce those rocks and indurated bodies which constitute the basis of our vegetable soil; but, that indurating or consolidating operation is not the immediate object of our observation; and, to see the evidence of that operation, or the nature of that cause, requires a long chain of reasoning from the most extensive physical principles. our present subject of investigation requires no such abstract distant _media_, by which the effect is to be connected with its cause; the actual operation in general is the object of our immediate observation; and here we have only to reason from less to more, and not to homologate things which may, to men of narrow principles, appear to be of different kinds. but even here we find difficulty in persuading those who have taken unjust views of things; for, those who will not deny the truth of every step in this chain of reasoning, will deny the end to which it leads, merely because they are not disposed to admit the progress of that order which appears in nature. in the last chapter, i have been using arguments to prove that m. de luc has reasoned erroneously, in concluding the future stability of a continent; and i have been endeavouring to show that our continent is necessarily wasted in procuring food to plants, or in serving the various purposes of a system of living animals. we have now in view to illustrate this theory of the degradation of the surface of the earth; a theory necessarily leading to that system of the world in which a provision is made for future continents; and a theory explaining various natural appearances which otherwise are not to be understood. a door may thus be opened for the investigation of natural history, particularly that which traces back, from the present state of things, those operations of nature which are more immediately connected with what we take much pleasure to behold, viz. the surface of the earth stored with such a variety of beautiful plants, and inhabited by such a diversity of animals, all subservient to the use of man. there are two ways in which we may look for the transactions of time past, in the present state of things, upon the surface of this earth, and read the operations of an ancient date in those which are daily transacted under our eye. the one of these is to examine the soil, and to trace the origin of that which we find loose upon the surface of the earth, or only compacted by the soft and cohesive nature of some of its materials. in thus studying the soil we shall learn the destruction of the solid parts; and though, by this means, we cannot form an estimate of the quantity of this destruction which had been made, we shall, upon many occasions, see a certain _minimum_ of this quantity which may perhaps astonish us. the second method here proposed, is to examine the solid part of the earth, in order to learn the quantity of matter which had been separated from this mass. here also we shall not be able to compute the quantity of what had been destroyed; but we shall every where find a certain _minimum_ of this quantity, which will give us an extensive view with regard to the operation of the elements and seasons upon the surface of this earth. we shall now examine more particularly those two ways of judging with regard to the operations of time past, and the changes which have been made upon the surface of our land, by those active causes, which, being in the constitution of this earth, must continue to operate with undiminished power, and tend to preserve the _whole_ amidst the destruction of its particular parts. the quality of the soil or travelled earth of the globe is various; because the solid parts, from the destruction of which the soil is formed, consist of very different substances, in the different portions of each country. thus, in one part of a country, the soil will be calcareous, or containing much of that species of substance; in another, again, it will be argillaceous; in another sandy, where the prevailing substance is siliceous. these are the original soils; other substances may be considered as adventitious to this soil, though natural to the surface of the earth, which is covered with plants and animals. the substance of those animal and vegetable bodies, mixed with the soil, adds greater fertility to the earth, and gives a soil which is still more compounded in its nature, but still composed of those materials now enumerated. we have been now supposing the solid parts below, or in the same field, as furnishing materials of which the soil is formed; this soil then partakes of the nature of those solid parts, whether more simple or more compound. there is, however, another subject of variety, or still greater composition in soils; this is the transportation of materials from a distance; and this, in general, is performed by the ablution of water, in following the declivity of the surface. but sand is sometimes travelled by the wind, and proceeds along the surface of the earth, without regard to the declivity, and changes the nature of soil in those places which happen to be exposed to this accident. there cannot be any extensive, great, or distant travelling of sand or soil by means of the wind, except in those places which are sterile for want of rain, and thus are destitute of rivers and of streams; for, these running waters form every where a bar to this progressive movement of the soil, even if the sterility or dryness should permit the blowing of the sand. but the operation of streams and rivers, carrying soil and stones along the surface of the earth, is constant, great, and general over all the globe, so far as a superfluity of water, in the seasons of rain, falls upon the earth. from the amazing quantity of those far travelled materials, which in many places are found upon the surface of the ground, we may with certainty conclude, that there has been a great consumption of the most hard and solid parts of the land; and therefore that there must necessarily have been a still much greater destruction of the more soft and tender substances, and the more light and subtile parts which, during those operations of water, had been floated away into the sea. this appears from the enormous quantities of stones and gravel which have been transported at distances that seem incredible, and deposited at heights above the present rivers, which renders the conveyance of those bodies altogether inconceivable by any natural operation, or impossible from the present shape of the surface. this therefore leads us to conclude, that the surface of the earth must have been greatly changed since the time of those deposits of certain foreign materials of the soil. examples of this kind have been already given. i shall now give one from the journal de physique. «les bords du rhône aux environs de lyon, et sur la longueur de quarante lieues, et de plus, des montagnes entières, dans le même pays, sont formes de pierres dont on ne trouve les analogues que dans la suisse. ce fait presqu'incompréhensible est accompagné de beaucoup de circonstances qui méritent d'être détaillées dans un discours plus longue que celui-ci. il y a cependant une que je ne peux pas m'empêcher de rapporter ici, comme une suite de ce que je viens de dire. «dans cette grand catastrophe, à laquelle j'attribue le transport de ces matières alpines, il se fit de grandes échancrures dans le jura; les plus profondes que j'aie vues sont celles de jougue de sainte-croix, du val de mousthier travers, de someboz au val de saint-inver, une cinquième aux environs du village de grange, trois lieues plus bas que bienne, et une sixième à quatre à cinq lieues plus bas que soleure, à l'endroit dit la cluse. cette dernière est la plus profonde, et se trouve de niveau avec les eaux de l'aar. beaucoup de ces matières étrangères au jura, ont passé par ces échancrures, et sans doute, par bien d'autres et se sont répandues, dans plusieurs de ces vallées. j'en ai vu un suite bien marquée qui a passé par jougue, par saint-antoine, part mont perreux, les grangettes, les granges friards, oye, et qui est allée jusqu'aux plaines de pontarlier. cette suite est en ligne droite vis-à vis l'échancrure de jougue, et la direction de la vallée qui est au bas de ce village. on en trouve quelques morceaux à metabiefs, mais je n'en ai point vu aux longevilles, ni à roche-jean. il y en a au-dessus de saint-croix ou d'autres ont pu passer aussi pour aller de même aux environs de portarlier. il y en a dans le val de mousthier-travers jusqu'au dessus de village de butte; elles ont même passé les roches de saint-sulpice du côté des verrières de suisse, ou l'on a été obligé d'en faire sauter de gros blocs avec de la poudre pour dégager la grande route; il y en a dans les vallées de tavannes, et de delemont; on en trouve bien plus loin, j'en ai vu près de roulans, et je ne douterois pas que les pierres meulières de moissez et des environs n'eussent la même origine.» m. de saussure, who has so well observed every thing that can be perceived upon the surface of the earth, gives us the following remarks which are general to mountainous countries. (voyages dans les alpes, tome d § ). «dans le haut des vallées entourées de hautes montagnes, on ne voit point de cailloux roulées, qui soient étrangers à la vallée même dans laquelle on les trouve; ceux que l'on y rencontre ne sont jamais que les débris des montagnes voisines. dans le plaines au contraire, et à l'embouchure des vallées, qui aboutissent aux plaines et même assez haut sur les pentes des montagnes qui bordent ces plaines, on trouve des cailloux et des blocs que l'on diroit tombés du ciel, tant leur nature diffère de toute ce que l'on voit dans les environs.» here are facts which can only be explained in supposing that the valleys have been hollowed out of the solid mass, by the gradual operation of the rivers. in that case stones, travelled from a far, will be found at considerable heights, upon the sides of the valleys at their under end, or where, as our author says, they terminate in plains. we have a striking example of the operation of time and the influences of the atmosphere, in wasting the surface of the rocks, and forming soil upon the earth; this is the kaolin of the chinese, or the true porcelain earth, which is the produce of granite countries. the feldspar of the granite rock exposed to the atmosphere is corroded very slowly indeed, by the effects of air and moisture, and in having the soluble earth or calcareous part of its composition dissolved; the surface of this stone, thus, in a long course of time, becomes opaque in having the white siliceous earth exposed to view, and thus appears like a calcined substance. the snows and rain detaches from this surface of the rock the white earth, which being deposited in the plain below, forms a stratum of kaolin more or less pure, according to the circumstance of the place. as this operation of the atmosphere upon the surface of granite is so extremely slow as to be altogether unmeasurable to man; and as there are in many places of the earth inexhaustible quantities of this kaolin, notwithstanding a small portion only of the ablution of the rock had been retained upon the surface and deposited by itself, it must appear that much time had been required for amassing those beds of kaolin, and that these operations, which in the age of a continent is nothing, or only as a day, are, with regard to the experience of man, unmeasurable. for approbation of this theory, it is not necessary to show, that wherever there is granite found, there should be also kaolin observed; but it is necessary that wherever kaolin is found, there should be also granite or feldspar to explain its origin; and to this proof the theory is most willingly submitted. the following are the places which have come to my knowledge. first loch dune in the shire of ayr; this lake receives its water from the granite hills which are at its head. secondly, some small lakes which receive the washings of the granite mountain, crifle, in east galloway. thirdly, cornwall, a county in which i have not been, but which is sufficiently known as possessing kaolin and granite. another example from a very distant country we have both from m. pallas, in the oural mountains, and from m. patrin, who has given a mineralogical _notice_ of the douari, _journal de physique, mars_ . here we find the following observation. «parmi les chose intéressantes qu'offrent les rives de chilea, on remarque au dessous de la fonderie, des collines de petunt-fé blanc comme la neige, parsemé de mica argentin de la plus grande ténuité. dans le voisinage de ce petunt-fé est une argile micacée, qui en est peut-être une décomposition: on essaya en ma présence d'en faire de la poterie qui avoit tous les caractères du meilleurs biscuit de porcelaine.» we have now been endeavouring to illustrate the wasting and washing away of the solid land, in the examples of decayed rocks and water worn stones, all of which are traceable, though at a great distance, to their source; we are now to consider another species of substance, which is still more particular as to the place of its production, or to its original situation, this being only in the veins of the earth. among all the various productions of mineral veins, we have only now in view some particular metallic substances which do not seem to waste and be dissolved, as many of them are, in being long exposed to the influence of air and rain. when, therefore, the solid parts of the land are wasted in time, and carried away from the surface of the earth, the contents of the veins, which are occasionally found in those decayed parts of the land, are also carried away in the stream; but as the specific gravity of those metallic contents is much greater than the other stony materials moved in the stream, they sink to the bottom, and tend much more to be deposited upon the land, than those stones which had moved with them from their place. hence it is, that deposits, rich in those metallic substances, are formed in certain places of the soil; and these are sought for, upon account of the value of their contents. thus, stream tin, which in the time of the romans formed a subject of traffic, is still found in the soil of cornwall, even in great profusion, at this day. nothing can tend more to illustrate this travelling of the wasted surface of the solid land, than the contents of those mineral veins suffering in the general destruction of things, but partly saved from that total ablution by which so much of the solid parts had been made to disappear; and nothing can, in a more beautiful manner, show this order of things, than the method practised by the cornish miners in quest of the original country of that metal, by _shoding_, (as it is called) upwards in running back the tract in which the stream tin had been conveyed. this is done by trying parcels of the soil, in always mounting to see from whence the mineral below had come. gold is thus found almost in every country but it is only in the most sparing manner that it may thus be in general procured, by reason of the few veins in which gold is found, and the small quantity of this metal contained in those veins. america, however, affords an example of veins rich in gold, and it is also there that quantities of stream gold is found in the soil, bearing a due proportion to the number and riches of the veins. i shall give an example concerning the situation in which this stream gold is found in peru (voyage au pérou, par m. bouguer, page .) «cette cordelière occidentale contient beaucoup d'or de même que le pied de l'orient, et celui d'une autres chaîne très-longue qui s'en détache un peu au sud de popayan, et qui après avoir passé par santa fé de bogota, et par mérida, va se terminer vers caracas sur la mer du nord; outre que l'or en paillettes occupe toujours des postes assez bas à l'égard du reste de la cordelière, on ne peut aussi jamais le découvrir qu'en enlevant presque toujours deux couches de différentes terres qui le cachent. la première, qui est de la terre ordinaire, a trois ou quatre pieds d'épaisseur et quelquefois dix ou douze. on trouve souvent au dessous une couche moins épaisse qui tire sur le jaune, et plus bas est une troisième qui a une couleur violette, qui a souvent trois ou quatre pieds d'épaisseur, mais qui n'a aussi quelquefois qu'un pouce, et c'est cette troisième dans laquelle l'or est mêlé. au dessous la terre change encore de couleur, elle devient noire comme à la surface du sol, et elle ne contient aucun métal. d'ailleurs on ne creuse pas indistinctement par tout. on se détermine à chercher en certains endroits plutôt qu'en d'autres par la pente de terrain. on agit comme si l'or avant que d'avoir été couvert par les deux couches supérieures, avoit été charrié par des eaux courantes. on s'est assuré aussi que les terres une fois _lavées_ ou dépouillée de leurs richesses n'en produisent point d'autres; ce qui prouve que l'or y avoit été comme déposé.» therefore, whether we consider the quantity or the quality of the materials which are found composing the soil upon the surface of the earth, we must be led to acknowledge an immense waste of the solid parts, in procuring those relicts which indicate what had been destroyed. we have now to examine what is left of that solid part which had furnished the materials of our soil; this is the part which supports the vegetable or travelled earth, and this earth sustains the plants and animals which live upon the globe. it is by this solid part that we are to judge concerning the operations of time past; of those destructive operations by which so great a portion of the earth had been wasted and carried away, and is now sunk at the bottom of the sea. man first sees things upon the surface of the earth no otherwise than the brute, who is made to act according to the mere impulse of his sense and reason, without inquiring into what had been the former state of things, or what will be the future. but man does not continue in that state of ignorance or insensibility to truth; and there are few of those who have the opportunity of enlightening their minds with intellectual knowledge, that do not wish at some time or another to be informed of what concerns the whole, and to look into the transactions of time past, as well as to form some judgment with regard to future events. it is only from the examination of the present state of things that judgments may be formed, in just reasoning, concerning what had been transacted in a former period of time; and it is only by seeing what had been the regular course of things, that any knowledge can be formed of what is afterwards to happen; but, having observed with accuracy the matter of fact, and having thus reasoned as we ought, without supposition or misinformation, the result will be no more precarious than any other subject of human understanding. to those who thus exercise their minds, the following remarks may furnish a subject for some speculation. now, though to human policy it imports not any thing, perhaps, to know what alterations time had made upon the form and quantity of this earth, divided into kingdoms, states, or empires, or what may become of this continent long after every kingdom now subsisting is forgotten, it much concerns the present happiness of man to know himself, to see the wisdom of that system which we ascribe to nature, and to understand the beauty and utility of those objects which he sees. there are two different operations belonging to the surface of this globe which we are now to consider, and by which we shall be enabled to form some computation of what had been in space and time, from that which now appears. moving water is the means employed in both those operations; but, in the one case, it is the water of the sea; in the other again, it is the water of the land. the effect of the one operation is the wasting of the coast, and the diminution of that basis on which our land and soil depends; of the other, again, it is the degradation of our mountains, and the wasting of our soil. in the course of this last operation, there is also occasionally land formed in the sea, in addition to our coast. with regard to the wearing of the coast by the agitation of the waves, this is an operation of which some understanding is to be formed from the surest of all records, from a careful examination of our shores which are in this decaying state, and by observing what has been removed from those portions which we find remaining. few people have either the skill or the opportunity of thus judging of the state of our earth from that which actually appears; but there is no person, who studies this science of geology, that may not satisfy himself with regard to the truth of this theory, by looking into our maps and charts, and making proper allowances for causes which cannot appear in the maps, but which may be understood by a person of knowledge making observations on the spot. in order to assist this study, the following observations may be made. it is a general observation among mariners, that a high coast and rocky shore have deep water; whereas a low coast, and sandy shore, are as naturally attended with shallow water. the explanation of this fact will appear by considering, that a steep rocky coast is occasioned by the sea having worn away the land; and, when that is the case, we are not to expect sand should be accumulated upon that shore, so as to make the sea shallow. look round all the coasts of great britain and ireland that are exposed to the wide ocean, as likewise those of france and norway, deep water, and a worn coast, are universally to be acknowledged. if again the coast is shallow, this is a proof that the land affords more materials than the sea can carry away; consequently, instead of being impaired, the coast may here increase and be protruded from the land. such is the case in many places along the coast of north america, where several reasons concur in accumulating sand upon that coast; for, not only is the shore plentifully provided with sand from the rivers of that continent, but also the sand of the mexican gulf would appear to be carried along this coast with the stream which flows here towards the north, and which has thus contributed to form the banks of newfoundland. the second general observation is to be considered as respecting the shape of coasts, in like manner as the first had in view their elevations. now, it is plain that the shape of the coast, in any part of the land, must depend upon a combination of two different causes. the first of these is the composition of the land or solid parts of the coast; if this be uniform and regular, so will be the shape of the coast; if it is irregular and mixed, consisting of parts of very different degrees of hardness and resistance to the wasting operations, the coast will then be, _cet. par._ irregular and indented. the second, again, respects the wearing power. if this wearing power shall be supposed to be equally applied to all the coast; and, if every part of that coast were of an equal quality or resisting power, no explanation could be given, from the present state of things, for the particular shape of that coast, which ought then to be wasted in an equable manner by the sea. but neither is the coast, of any extensive country at least, composed of such uniform materials; nor is the application of the wearing power to the coast an equal thing; and this will form the subject of another observation. the third general observation, therefore, regards the operations of the sea upon the coast, and the effects which may be perceived in consequence of that cause, independent of the qualities of the coast, or supposing them in general to be alike. here, according to the theory, we should expect to find deep water and an indented coast upon a country, in proportion as that coast is exposed to the violence of the sea, or is open directly to the ocean. we have but to look along the west coast of norway, the north-west of scotland, the west of ireland, and the south-west of england and of france; and we shall soon be convinced that the sea has made ravages upon those coasts in proportion to its power, and has left them in a shape corresponding to the composition of the land, in destroying the softer, and leaving the harder parts[ ]. [footnote : m. de lamblardie, _ingénieur des ponts et chaussées_, has made a calculation, seemingly upon good grounds, with regard to the wasting of a part of the coast of france, between the seine and the somme. this coast is composed of _falaises_, (or chalk cliffs, like the opposite coast of england), which are feet high above the level of the sea, composed of strata of marl, separated by beds of flint. this coast is found to be wasted, at an average, at the rate of one foot _per annum_. we may thus perhaps form some idea of the time since the coast of france and that of england had been here united, or one continued mass of those strata which are the same on both those coasts.] with those hard and rugged coasts of britain and ireland, let us contrast the east coasts; what a difference between these and the west side! upon the west side, there are no sand banks left upon the coast; the mariner has nothing there to fear but rocks. it is otherwise on the east; here we find a tamer coast, and, in many places, a sandy bottom. on the west, nothing appears opposed to the storm of the ocean except the hardest and most solid rock; on the east, we find coasts exposed to the sea which could not have remained in a similar situation on the west. let us but compare the two opposite coasts of england, viz. the promontory of norfolk and suffolk upon the one side, and pembrokeshire and carnarvonshire on the other, both similarly exposed, the one to the north east storm of the german sea, the other to the south west billows of the atlantic. what a striking difference! the coast in the bay of cardigan is a hard and strong coast compared with that of norfolk and suffolk; the one is strong schistus, the other the most tender clay; yet the soft coast stands protuberant to the sea, the harder coast is hollowed out into a bay; the one has no protection but the sands with which it is surrounded, the other had not remained till this day but for the protection of the most solid rocks of pembrokeshire and carnarvonshire, which oppose the fury of the waves. the last general observation which i shall propose, has, for its subject, a more enlarged view than those now taken of the coast, a view indeed which is not so immediately the object of our observation, but which is nevertheless to be made most evident, by means of the others now considered. we have seen that the land exposed to the sea is destroyed, and the coast wasted more or less, in proportion to the wearing causes, and to the different resisting powers opposed to those causes of decay; we are now to make our observations with regard to the extent and quality of that which has been already destroyed, a subject which can only be conjectured at from the scientific view which may be taken of things, and from the careful examination of that which has been left behind upon the different coasts. our land is wasted by the sea; and there is also a natural progress to be observed which necessarily takes place on this occasion; for, the coast is found variously indented, that is to say, more or less, according as the land is exposed to this wasting and wearing operation of the sea, and according as the wasted land is composed of parts resisting with different degrees of power the destroying cause. the land, thus being worn and wasted away, forms here and there peninsulas, which are the more durable portions of that which had been destroyed around; and these remaining portions are still connected with the main land, of which they at present form a part. but those promontories and peninsulas are gradually detached from the main land, in thus forming islands, which are but little removed from the land. an example of this we have in anglesay, which is but one degree removed from the state of being a promontory. these islands again, in being subdivided, are converted into barren rocks, which point out to us the course in which the lost or wasted land upon the coast had formerly existed. to be satisfied of this, let us but look upon the western coast of scotland; from the islands of st. kilda to galloway, on the one side, and to shetland on the other; in this tract, we have every testimony, for the truth of the doctrine, that is consistent with the nature of the subject. the progress of things is too slow to admit of any evidence drawn immediately from observation; but every other proof is at hand; every appearance corresponds with the theory; and of every step in the progress, from a continent of high land to the point of a rock sunk below the surface of the sea, abundant examples may be found. we do not see the beginning and ending of any one island or piece of country, because the operation is only accomplished in the course of time, and the experience of man is only in the present moment. but man has science and reason, in order to understand what has already been from what appears; and we have but to open our eyes to see all the stages of the operation although not in one individual object. now, where the nature of things will not admit of having all and every step of the progress to be perceived in one object, an indefinite progression in the various states of different objects, showing the series or gradation from a continent to a rock, must form a proof in which no deficiency will be found. i have given for example the coast of scotland; but all over the world where there is a coast not covered with sand, or where it is exposed to the violence of the sea, it is the same. take the map of any country, provided it be sufficiently particular, and you will see the breaking of continents or islands, first, into promontories or peninsulas; secondly, into islands which stand on the same solid basis with the continent; and, lastly, into rocks which are related to the islands, in like manner as those parasitical islands are related to the head lands and the shore. here is a general fact, from the simple inspection of which we must conclude one of two things; either that those rocks and smaller islands, which we have termed parasitical, are in a state of progression, by which in time they will be joined to the main land, and form one continent; or that they are in a state of degradation, by which in time they will be made to disappear. there is no other supposition to be made; and, of that alternative, there is no room to hesitate a moment which to choose. this is not a matter of mere probability, it is the subject of physical demonstration. should we find an old manuscript in a similar condition, we could not conclude with more certainty, that the deficient or intervening places had been destroyed, than we here conclude that the part which is now wanting, between the two remaining portions of the same rock or strata, had once connected those two portions, and had been destroyed by the operation of those causes which are every day employed in still increasing the breach. though over all the world, where the shore is washed bare by the sea, examples are to be found which require but to be seen to give compleat conviction, it is not in every place that the eye of a naturalist has been employed in taking this view of the coast; nor is it upon every occasion that enlightened philosophers of this kind have given their thoughts upon the subject. m. de spallanzani has given us the following observations with regard to the coast of italy[ ]. [footnote : observations sur la physique, etc. juliet .] «autant l'intérieur du petit bourg de porto-venere et les rochers qui l'environnent sont a l'abri des tempêtes, autant les parties extérieures sont exposées aux coups de mer les plus violens, lorsqu'elles sont en proie au deux terribles vents d'afrique et à celui du sud-est. ce dernier en particulier soulève les flots avec tant de violence et à une telle hauteur contre les écueils qui servent de défense à ce petit terrain, que la mer semble menacer de l'engloutir. j'ai été le témoin d'un de ces orages, et quoique je fusse à l'abri de tout danger, je ne pourroit vous representer l'horreur que me fit éprouver ce spectacle. j'ai voulu prendre avec exactitude la hauteur moyenne de l'élevation des flots dans les plus violens coups de vent; et quand je vous en parlerai vous serez étonné de leur force et de l'étendue de leurs effets. les rochers qui sont à la partie méridionale de porto-venere se rongent et se détruisent peu-à-peu de même que les trois isles voisines _tiro_, le _petit tiro_, et _palmarin_. on le remarque surtout dans cette dernier: les bords voisins de la terre ont une pente douce; ils sont couverts d'arbres et de plantes, tandis que la partie opposée est déserte et inaccessible couverte de précipices, de ruines et d'horreurs; les autres parties du rivage sont renfermées par la rivière du ponent et par celle du levant, de même que celles qui s'approchent des côtes de provence. il me paroît que la mer a beaucoup gagné sur le terre dans ces parages; et pour parler seulement de palmarin, la plus grande, et la plus remarquable des trois îsles que j'ai nommées, je crois être suffisamment fondé pour conclure que la même pente facile et longue qu'on observe du côte de la terre avoit aussi existé du côte de la mer; mais que cette dernière avoit été détruite par les orages, qui se sont succédés pendant le cours de siècles. la vue réfléchie de ces trois îsles me force à les regarder comme ayant été autre fois réunies, et formant une îsle seule par leur réunion, ou plutôt comme une presqu'île attenante à porto-venere.» we have a still more interesting observation made upon this same coast of italy, by a naturalist to whom the world is much indebted for his excellent remarks upon what he has, by his great industry, brought to light. i mean the chevalier de dolomieu; where-ever he goes, natural history reaps the benefit of the most enlightened observations. we are now to avail ourselves of his mémoire sur les iles ponces. the pumice islands form part of a chain of land that may be traced forming a circular line from the cape missene to the mount circello at the other side of the gulf of gaeta. the islands of ischia and procida, which form part of this chain of land, might, from the inspection of the map, be allowed as having once formed a continuation of the land from the continent of italy, even without the testimony of natural history, that traces this connection from the materials of those masses which now are separated. the pumice islands form the middle part of that chain, and are the farthest removed from that continent of which it is probable they once formed a part. they are connected with the promontory of missene on the one hand, as being of the same or similar volcanic origin, and on the other with mount circello, by a curious circumstance in the island zanone, which, but a little more of the devouring operation of the sea, would have concealed from our observation. the island of ventotiene, which is the nearest of them to ischia, would appear to be the ancient island of pendataria, in which julia was confined. the marks of degradation in this island, i would wish to give in the chevalier's own words, (p. .) «cette îsle continue à être devorée par la mer, elle l'attaque dans toutes les parties de son contour, où elle trouve peu de resistance, et elle ne cesse de creuser, principalement, tous les escarpemens du nord. il paroît, par les vestiges des antiquités qui sont sur la pointe dite _di nevola_, que sous l'empire de césar cette îsle avoit encore une étendue plus considérable. il s'y fait journellement des éboulemens; on peut prévoir qu'elle diminuera progressivement, qu'elle se divisera, et que dans les temps à venir elle sera réduite aux rochers de laves qui la supportent, et qui seuls peuvent résister, pendant une longue suite de siècles, à tous les efforts des flots; ce ne sera sûrement pas la seule terre que le temps et la mer auront dévorée, et que les vicissitudes de la nature ont fait disparoître avant que l'histoire en ait pu constater l'existence.» as the island of ventotiene connects this group of the pumice islands with the continent of missene, that of zanone, on the other side, connects them with the continent at mount circello. here is a fact of which our author now gives proper evidence. it would appear that mount circello is composed of an alpine limestone. but in the north end of the island of zanone, the chevalier de dolomieu finds a small part of a similar limestone in vertical strata, closely united with the volcanic materials of the islands now under consideration. it is impossible that this portion of calcareous rock could be formed in its present situation, and we have but to examine nature in order to be convinced that this limestone part had been once continued from mount circello. here again i beg leave to give this author's own words, (page .) «cette réunion de deux matières aussi différentes par leur origine que le font celles qui forment l'isle zanone, est une circonstance des plus singuliers. la pierre calcaire ne contient point de coquillages; sa densité sa dureté; son odeur fétide annonce une origine ancienne; elle n'est point formée par un dépôt de nouvelle date; elle diffère des pierres calcaires-coquillière qui recouvrent les volcans du padouan et du vicentin, et de celles qui se sont mêlés avec les produits du feu dans les volcans éteintes de la sicile: les laves ici reposent sur elle: elle paroît donc antérieure à l'époque des irruptions qui ont élevé les îsles ponces. par sa nature elle est semblable aux pierres du mont circé, et à celles de l'intérieure de l'apennin; il semble que cette portion de montagne calcaire, abstraction faite des matières volcaniques qui lui sont réunies, a appartenu à quelqu'unes des montagnes qui dépendent de la chaine qui traverse l'italie; car il n'est pas possible que ni elle ni le mont circé ayent été formés seules et isolés ainsi que nous les voyons. mais quand ont-ils été détachées? étoient-ils déjà isolés lorsque les feux ont commencé la formation des îsles ponces? ou seroit-ce la même révolution qui les auroit séparés du continent, et qui a opéré le désordre que nous voyons dans ces îsles volcanique? on ne peut former sur toutes ces questions que des conjectures bien vagues.» our present inquiry is only with regard to the operation of those causes which we now perceive to be acting upon the coasts of the land; which must be considered as having been operating for a long time back, and which must be considered as continuing to operate. one example more i wish to give, not only as it is much to the purpose, and properly described, but because it contains the natural history of a coast well known from the circumstance of the giant's causeway which it contains; a coast composed of stratified chalk indurated and consolidated to a species of marble or lime-stone, and of great masses of basaltes or columnar whin-stone. now, though our present object is not the formation of land, yet, knowing the mineral constitution of this land, the coast of which we are considering as having been worn by the action of the sea, the view here to be given, of the white marble and basaltic cliffs, is satisfactory in the highest degree. it is from letters concerning the northern coast of the county of antrim, by the reverend william hamilton, a. m. «the chalky cliffs of the island of raghery, crowned by a venerable covering of brown rock, form a very beautiful and picturesque appearance as one sails towards them; and, if the turbulence of the sea does not restrain the eyes and fancy from expatiating around, such a striking similitude appears between this and the opposite coast, as readily suggests an idea that the island might once have formed a part of the adjoining country, from whence it has been disunited by some violent shock of nature. «you, to whom demonstration is familiar, will wonder to see two shores, seven or eight miles asunder, so expeditiously connected by such a slender and fanciful middle term as apparent similitude; and yet the likeness is so strong, and attended with such peculiar circumstances, that i do not entirely despair of prevailing even on you to acknowledge my opinion as a probable one. «it does not appear unreasonable to conclude, that, if two pieces of land, separated from each other by a chasm, be composed of the same kind of materials, similarly arranged, at equal elevations, these different lands might have been originally connected, and the chasm be only accidental. for, let us conceive the materials to be deposited by any of the elements of fire, air, earth, or water, or by any cause whatever, and it is not likely that this cause (otherwise general) should in all its operations regularly stop short at the chasm. «the materials of which the island of raghery is composed are accurately the same as those of the opposite shore; and the arrangement answers so closely, as almost to demonstrate, at first view, their former union. but to explain this more clearly, it will be necessary to give you a general sketch of this whole line of coast. «the northern coast of antrim seems to have been originally a compact body of lime-stone rock, considerably higher than the present level of the sea; over which, at some later period, extensive bodies of vitrifiable stone have been superinduced in a state of softness. the original calcareous stratum appears to be much deranged and interrupted by those incumbent masses. in some places it is depressed greatly below its ancient level; shortly after it is borne down to the water's edge, and can be traced under its surface. by and by it dips entirely, and seems irretrievably lost under the superior mass. in a short space, however, it begins to emerge, and, after a similar variation, recovers its original height. «in this manner, and with such repeated vicissitudes of elevation and depression, it pursues a course of forty miles along the coast from lough foyle to lough larne. «it naturally becomes an object of curiosity to inquire what the substance is from which the lime-stone seems thus to have shrunk, burying itself (as it were in terror) under the covering of the ocean: and, on examination, it appears to be the columnar basaltes, under which the lime-stone stratum is never found; nor indeed does it ever approach near to it without evident signs of derangement. «thus, for example, the chalky cliffs may be discovered a little eastward from portrush; after a short course, they are suddenly depressed to the water's edge, under dunluce castle, and, soon after, lost entirely in passing near the basalt-hill of dunluce, whose craigs, near the sea, are all columnar. at the river bush the lime-stone recovers, and skims a moment above the level of the sea, but immediately vanishes in approaching towards the great basalt promontory of bengore, under which it is completely lost for the space of more than three miles. «eastward from thence, beyond dunsaverock castle, it again emerges, and, rising to a considerable height, forms a beautiful barrier to white park bay and the ballintoy shore. after this it suffers a temporary depression near the basalt hill of knocksoghy, and then ranges along the coast as far as ballycastle bay. «fairhead, standing with magnificence on its massy columns of basaltes, again exterminates it; and once again it rises to the eastward, and pursues its devious course, forming, on the glenarm shores, a line of coast the most fantastically beautiful that can be imagined. «if this, tedious expedition have not entirely worn out your patience, let us now take a view of the coast of ragery itself, from the lofty summit of fairhead, which overlook it. westward we see its white cliff rising abruptly from the ocean, corresponding accurately in materials and elevation with those of the opposite shore, and like them, crowned with a venerable load of the same vitrifiable rock. eastward, we behold it dip to the level of the sea, and soon give place to many beautiful arrangements of basalt pillars which form the eastern end of the island, and lie opposite to the basaltes of fairhead, affording in every part a reasonable presumption that the two coasts were formerly connected, and that each was created and deranged by the same causes extensively operating over both. «but it is not in these larger features alone that the similitude may be traced; the more minute and accidental circumstances serve equally well to ascertain it. «thus, an heterogeneous mass of freestone, coals, iron-ore, etc. which forms the east side of ballycastle bay, and appears quite different from the common fossils of the country, may be traced also directly opposite, running under rathlin, with circumstances which almost demonstrably ascertain it to be the same vein. «what i would infer from hence is, that this whole coast has undergone considerable changes; that those abrupt promontories, which now run wildly into the ocean, in proud defiance of its boisterous waves, have been rendered broken and irregular by some violent convulsion of nature; and that the island of ragery, standing as it were in the midst between this and the scottish coast, may be the surviving fragment of a large tract of country which, at some period of time, has been buried in the deep.» besides this argument of the gradation from a continent of land to a bare rock, we have another from the consideration of those rocks themselves, so far as these could not be formed by nature in their present state, but must have been portions of a greater mass. how, for example, could a perpendicular mountain, such as st. kilda, have been produced in the ocean? of whatever materials we shall suppose it formed, we never shall find means for the production of such a mass in its present insulated state. let us take examples of this kind near our coast, and of known rocks. staffa and ailsa, on the west coast, and the bass, upon the east, are mountains of either whin-stone or granite, similar to many such mountains within the land; and they are perpendicular around, except perhaps on one part. it is demonstrable that such basaltic rock as contains zeolite and calcareous spar, as most of our whin-stones do, could not have been the eruption of a volcano, consequently those rocks must have been masses protruded in a fluid state, under an immense cover of earth at the time of their production; and they could not have risen immediately out of the sea, with all their various minerals, their veins and cutters, their faces and their angles. in like manner, the east coast of caithness is a perpendicular cliff of sand-stone, lying in a horizontal position, and thus forming a flat country above the shore. but along this coast there are small islands, pillars, and peninsulas, of the same strata, corresponding perfectly with that which forms the greater mass. now, shall we suppose those strata of sand-stone to have been formed in their place, and to have reached no farther eastward into the sea?--it is unsupposable. or, shall we conceive that the sea, which has made such depredations in land composed of much more solid materials, had spared this, and had not wasted much more than that now pointed out by the ruins which remain?--impossible; we must suppose that there had once existed much land where nothing now is found but sea. but, if we are to suppose much to have been wasted, where shall we stop in this process of restoring continents? that is the question now to be discussed. with this view, let us now turn our attention to the north-west coast of europe, in consulting the general as well as the most particular maps. upon the one extremity of britain, we find cornwall separating it as it were from the main land; and, from this promontory, the scilly isles pointing out what had been destroyed in that direction, which is here to be considered as the line of greatest resistance. but what a quantity of the soft materials, or less resisting parts on either side, has been destroyed! upon the other extremity of britain, we find the country of scotland, forming itself into promontories and islands, and those islands and rocks pointing out to us what had been the former extent of our continent and land around. but, in following this connection of things, we cannot refuse to acknowledge that ireland had formerly been in one mass of land with britain, in like manner as the orkneys had been with scotland[ ]. [footnote : i have the most satisfactory evidence of this fact, in finding the schistus of galloway and of england in the opposite coast of ireland, corresponding to its direction in stretching from the coasts of britain.] it will be still less possible to refuse the junction of england with the continent of france; the testimony of that peculiar body of chalk and flint, which borders each of those opposite coasts, forms an argument which is irrefragable. now, in order to complete our continent, we have only to connect the shetland islands with the coast of norway. but this is a notion which, however probable it may appear, is not proposed as a fact immediately supported by natural appearances; it is only to be considered as an enlarged view in which we may contemplate the operations of this earth upon a more extended scale; one which may be conceived as a step in our cosmogeny, and one which, while it illustrates the theory of the earth already given, is by no means required in order to confirm a theory founded upon appearances which leave no manner of doubt. chap. ix. _the theory illustrated, with a view of the summits of the alps._ there are two different directions in which we may observe the destruction of our land to proceed; in the one of these, the basis of our continent is diminished by the incroachment of the sea; in the other, again, it is the height of the land above the level of the sea that is lowered. we have been considering the incroachment of the sea upon the continent; let us now examine how far there may also appear sufficient documents, by which we may be led to conclude a long progress in time past, for the destruction of the solid mass of earth above the sea, without diminishing its basis. if we shall suppose this earth composed of horizontal strata, and of one level surface, without the least protuberance remaining by which we might be informed of what had been removed by time in the operation of second causes, we should be ignorant of every thing of cosmogeny but this, that the strata of the globe had been originally formed (by the sea) in the same shape as we had found them on the surface of the land. but this is not the shape of the surface of our continent: we have every where abundance of eminences, sufficient to give us great information with regard to what had passed in former periods of time, if the strata of the globe were in that regular shape which they had originally assumed in being deposited at the bottom the sea. the strata, however, are not in that regular shape and position from whence we might learn, by examining the remaining portions, what had been carried away from the surface in general; they are found variously inclined to the horizon; and this we find both occasioned from the fracture and flexure of those bodies, thus changed from their natural horizontal state. thus, though there are in many places immense masses of strata cut off abruptly, and exposed to view, without the remainder appearing, we cannot from hence form any estimate of the general quantity of destruction; at the same time, it must be evident, from a general inspection, that there has been an immense quantity removed; and that an immense time had been required in bringing about those revolutions of things, which are not done by violent changes, but by slow degrees. besides that general conclusion with regard to the destruction of the strata, there is also in many places a demonstration of that fact, from a measured minimum of the quantity which had been removed. it is to the mining business chiefly that we are indebted for that demonstration of which we now shall give an example. the coal strata, about newcastle upon tyne, dip to the south-east at the rate of one in twelve, or thereabouts. this is but little removed from the horizontal position; at the same time, the strata come all up to the soil or surface in a country which is level, or with little risings. but in those strata there is a slip, or hitch, which runs from north-east to south-west, for or miles in a straight line; the surface on each side of this line is perfectly equal, and nothing distinguishable in the soil above; but, in sinking mines, the same strata are found at the distance of fathoms from each other. here therefore is a demonstration, that there had been worn away, and removed into the sea, fathoms more from the country on the one side of this line, than from that on the other. it is far from having given us all the height of country which has been washed away, but it gives us a minimum of that quantity. the examination of what is commonly called a secondary country is not sufficient to give us an idea of the immense operation of time in wearing the surface of this earth. it is not that those countries of inferior hardness and elevation have been spared in the course of time, but because we have not, in those levelled countries, such great remainders, by which we are to judge the quantity of what is lost. in the alpine country, again, though it be the same system of things with that which takes place in the lower country, the revolution of things is more marked for our view; and the ravages of time, in destroying the solid parts of the globe, in order to make soil of that which is removed, may be seen in all the steps of that important operation; whereas, in the more level countries, the scale of elevation is imperceptible, and that of time is so slow as renders our examination fruitless. it is the alps, therefore, chiefly that we are to take for an example, in tracing this operation of nature upon the surface of this earth, and forming some idea of the course of time that must have flowed during that operation in which the height of our land had been diminished. on whatever side we approach the alps, we find some great river discharging the waters which had been gathered above, and with that water all the waste of earth and stone which had been made among those lofty masses of decaying rock. now, we find this river running in a valley proportioned, in general, to this vehicle, in which is travelled the wreck of ruinous mountains. spacious plains attend those mighty streams; and, tho' sometimes we find the greatest rivers much confined between approaching hills of solid rock, the valley opens again, and, on the whole, is always corresponding to the current of water which has successively run in all the quarters of this plain. here a question occurs; has this valley been made by the operation of the river itself, or has it been the effect of other causes? let us now resolve that question. if the valley was made for the river by any other natural cause, either we should tell by what means this work had been performed, or all reasoning upon the subject is at an end, and fancy substituted in its place. if again the river be considered as the means employed by nature in making this valley, then all the solid parts between the bounding mountains must have been removed, and the fertile plains must have been formed by the water depositing those materials which we find in the soil, and which had come originally from the solid mountains. there is no occasion to enter into any argument to prove this fact; nobody that examines the matter will find any reason to doubt; and it would be as unreasonable for those to doubt who have not examined, as for those who find no reasonable subject of doubt to disbelieve. we are now to suppose the great river to have formed the valley and extensive plain in which the water runs,--a valley corresponding to the grandeur of the river by which it has been formed. but, as we ascend this great valley, we find other valleys branching from this main valley; and, in all those subordinate valleys, we find rivers corresponding in like manner with the magnitude of the valley. here, therefore, is infinitely more than a single river, and a valley corresponding to the river; here is a _system_ of rivers and of valleys, things calculated in perfect wisdom, or properly adapted to each other. now it is just as easy, by our theory, to explain this system of rivers and valleys, as it is to understand the single appearance of a river and a valley. but it is only in this manner that such a complicated operation, of a series in rivers and their valleys, is to be explained; and we can neither suppose the land to be formed with this intention by a supernatural cause, nor imagine any other natural cause so arranging things, upon the surface of the earth, as to form this perfect system, which holds of nothing but itself; a system in which is manifested wisdom, so far as all the parts are properly adapted to each other, and thus made to answer that intention which is so visible in the economy of this world. the direction of the principal valleys of the alps, or every mountainous region of the globe, may be considered as proceeding from the centre of that region to the plain country in which each river is to terminate; each secondary river with its valley then branches from the primary as from a stem, consequently runs in a direction perpendicular or inclined to the other. but the secondary rivers also have their branches; and subordinate branches still are branched. in thus tracing rivers and their branchings, we come at last to rivulets that only run in times of rain, and at other times are dry. it is here i would wish to carry my reader, in order to be convinced, with his proper observation, of this great fact,--that the rivers, in general, have hollowed out their valleys. the changes of the valley of the main river are but slow, the plain indeed is wasted in one place, but it is repaired in another, and we do not perceive the place from whence that repairing matter had proceeded. therefore, that which here appears does not immediately suggest to the spectator what had been the state of things before the valley had been hollowed out, or before that plain, through which the river runs so naturally as being in the lowest place, was made. but it is otherwise in the valley of the rivulet; no person can examine this subject without seeing that the rivulet carries away matter which cannot be repaired except by wearing away some part of the mountain, or the surface of that place upon which the rain, which forms the stream, is gathered. in those rivulets, or their little plains, we see the detached parts remaining in the soil, and also the place from whence those detached parts were taken. here we need no long chain of reasoning from effect to cause; the whole operation is in a manner before our eyes. in this case, it requires but little study to replace the removed parts; and thus to see the work of nature, resolving the most hard and solid masses by the continued influences of the sun and atmosphere. in this state of things, we are easily made to understand how heavy bodies are travelled along the declivity of the earth, by means of water running from the height. such is the system of rivers and their valleys; nor is there upon the continent a spot on which some river has not run. but, in the alps of switzerland and savoy, there is another system of valleys, above that of the rivers, and connected with it. these are valleys of moving ice, instead of water. this icy valley is also found branching from a greater to a lesser, until at last it ends upon the summit of a mountain, covered continually with snow. the motion of things in those icy valleys is commonly exceeding slow, the operation however of protruding bodies, as well as that of fracture and attrition, is extremely powerful. to illustrate those operations of excavating the valleys of rivers and of thus undermining mountains which fall by their proper weight, i shall transcribe some descriptions of what is to be found among the alps. but first i would wish to carry my reader to the summit of that country, to examine the state of that part which nothing can have affected but the immediate influences of the sun and air. after having thus formed some idea of the summit of this wasting country, we shall next examine the valleys through which the materials of the degraded summit must have travelled. in order to give a proper idea of this central part of the alps, which is so interesting a part in the natural history of the earth, m. de saussure, in the plates of his _voyages dans les alpes_, tom. . has given us two views, the one in profile, the other in face, of the mont-blanc. i have caused copy those plates, which are necessary to be consulted in reading the following description of this centre of the alps. this author has taken much pains to form, to himself a proper idea of the object which we have now in view; and he gives a description of the mont-blanc as seen from the top of the cramont. it is that description which i am now to transcribe[ ]. [footnote : voyage dans les alpes, tom. .] § . «le premier objet de mon étude fut le mont blanc. il se présente ici de la maniere la plus brillante et la plus commode pour l'observateur. on l'embrasse d'un seul coup-d'oeil, depuis sa base jusqu'à sa cime, et il semble avoir écarté et rejeté sur ses épaules son manteau de neiges et de glaces pour laisser voir à découvert la structure de son corps. taillé presqu'à pic dans une hauteur perpendiculaire de toises, les neiges et les glaces ne peuvent s'arrêter que dans un petit nombre d'échancrures, et il montre partout à nud le roc vif dont il est composé. «sa forme paroît être celle d'une pyramide, qui presente au sud-est du côté du cramont une de ses faces. l'arrête droite de cette pyramide du côté du sud-ouest, monte au sommet, en faisant avec l'horison un angle de à degrés. l'arrête gauche du coté du nord-est, monte au même sommet sous un angle de à degrés, en sorte que l'angle au sommet est d'environ degrés. «cette pyramide paroît elle même composée de grands feuillets triangulaires ou pyramidaux. trois de ces grands feuillets ont leurs bases dans l'allée-blanche, et forment ensemble tout l'avant corps de la base de la pyramide. chacun de ces feuillets, vu de l'allée-blanche, paroît une grande montagne, je les ai décrits dans le chapitre précédent sous le noms de mont-pétéret, mont-rouge, et mont-broglia, § , , . mais du haut du cramont, on voit plus nettement leur forme, et leur ensemble, on distingue, par exemple, qu'ils sont eux-mêmes composés de grandes feuilles pyramidales; on voit que les injures du temps ont détruit la pointe du mont-rouge, tandis que celles des deux autres pyramides sont demeurées entières. «ces trois feuillets ne s'élèvent pas jusqu'à la moitié de la hauteur du mont-blanc; d'autres feuillets plus petits, situés derrière et au-dessus d'eux, et placés sur deux lignes principales qui convergent au sommet, achèvent de couvrir la face de cette grande pyramide. ces feuillets sont tous de forme pyramidale; les plus petits sont les plus aigus; j'en ai mesuré plusieurs, dont l'angle au sommet n'étoit que de degrés. tous, absolument tous, ont leurs plans parallèles à l'allée-blanche, et par conséquent dirigés du nord-est au sud-ouest. «§ . quant à la matière dont est composée cette grande et haute montagne, toute sa cime et toute sa base, tant au centre que du côté du nord-est, sont indubitablement de granit; mais le côté sud-ouest de la base, ou le mont-broglia que nous avons vu de près, § , est d'une pierre moins dure, mélangée de schorl, de feldspath, de mica, de quartz gras et de pyrites. «on voit très-bien du haut du cramont que cette partie de la base n'est point du granit; sa couleur est d'un brun rougeâtre, elle ne se termine point par des arrêtes vives et nettes, n'est point composée de grandes tables planes. ce font cependant des feuillets pyramidaux, mais petits et pressés les unes contre les autres; à mesure qu'ils s'approchent du sommet, et par cela même du coeur de la montagne, ils perdent leur couleur rouge, leurs angles deviennent plus vifs, leurs tables plus grandes et plus planes, et enfin prés de la cime, et à la cime même, ce sont de vrais granits parfaitement caractérisés. on peut donc conclure, que le corps entier du mont-blanc, et même ces bases avancées du côté de l'italie, sont toutes de granit, excepté la base de l'arrête extérieure du côté du sud-ouest. «§ . la montagne qui touche le mont-blanc du côté du nord-est, et qui, vue de genève, forme en quelque maniere le premiere escalier en descendant de la cime, est aussi composée de tables de granit qui paroissent dirigées du nord-est au sud-ouest. mais la sommité qui suit celle-ci en tirant toujours au nord-est, et qui forme le second escalier, paroît avoir quelques feuillets tournans autour de son corps pyramidal, comme les feuillets d'un artichaux, et comme j'ai dépeint l'aiguille du midi, _tome_ i. _pl._ . en tirant plus encore au nord-est, on reconnoît les jorasses que nous avons vues du haut du taléfre, § , elles paroissent d'ici, après le mont-blanc et ses escaliers, les sommités les plus élevées de toute cette chaîne, et elles semblent résulter de l'assemblage de plusieurs suites de feuillets pyramidaux convergents vers leur sommet. en général toutes les cimes élevées que l'on peut distinguer dans cette chaine, depuis le mont-blanc jusqu'au col ferret, sont soutenues par des augives composées d'une ou de plusieurs suites de feuillets pyramidaux appuyés les uns contre les autres; les extérieures ont leurs bases dans le fond de la vallée, et les intérieures remontent par degrés jusqu'au haut des cimes. les deux escaliers du mont-blanc sont les seules sommités qui n'aient pas des augives de ce genre. «§ . je demande á present quelle idée on peut se faire de l'origine de ces feuillets plans et de toutes ces pyramides grandes et petites qui résultent de leur assemblage, si on ne les considère pas comme les restes ou les noyaux les plus durs des couches qui out résisté aux ravages du temps, tandis que les parties intermédiaires, qui les lioient entr'elles, out été détruites par ces mêmes ravages. «mais jusqu'à quel point la crystallization a-t-elle contribué á déterminer ces formes pyramidales? doit-on considérer le mont-blanc ou telle autre de ces aiguilles, comme un énorme crystal? c'est une question de théorie que j'examinerai ailleurs. quant à présent je me contenterai de conclure, que la face méridionale de la chaîne centrale des alpes est, comme la face septentrionale de cette même chaîne, composée, pour la plus grande partie, de couches de granit à-peu-près verticales, et dirigées pour la plupart du nord-est au sud-ouest.» this theoretical question of our author is so properly connected with the natural history which he has here given us, that it is not difficult to resolve it in the most satisfactory manner. here is an enormous mass of granite, the origin of which we are not now inquiring after, but the causes of its present form. the internal part of this granite subsists in a state of the most perfect solidity; the external again is evidently in a decaying state. this is a fact which we learn from the nature of feldspar, of which granite is in part composed; this crystallised substance is every where decomposed, where long exposed to the atmosphere. but it is not this gradual decay of the mass of granite perishing equably from its external surface, and resolved into some of its component parts, that we are here to consider; it is only mentioned to show that the mass of granite is subject to decay, when exposed to the influence of the atmosphere, like every other compound mineral body, and to lose that perfect solidity which we find in the centre of the mass. we find the granite masses not only subject to decay from the external surface, by the decomposition of the feltspar, or the dissolution of its constituent parts, but also liable to be separated into blocks of different degrees of regularity, commonly rectangular or approaching to the rhombic shape. this is the consequence, either of larger veins and fissures, filled with matter which is still more dissolvable than is the substance of the granite, or else by imperceptible crevices or cutters, into which the atmospheric influences gradually insinuate, and form at last a visible separation. in examining the tops of granite mountains, or where this rock is exposed to the weather, we may perceive those two species of decay proceeding together. the external surface of the stone, where there is a sufficient mixture of feltspar, is separating into grains which form a species of sand, being nothing but the particles of granite separating by means of the decaying sparry part. but a similar progress may be observed, from the external surface penetrating in lines the mass of solid rock, and dividing that mass into the rectangular blocks into which those exposed places are gradually resolved. now the tops of all those mountains are formed into an assemblage of pyramids, declining in height from the central pyramid; and all those pyramids are again in like manner subdivided into lesser pyramids. but the smallest of those pyramids are no other than the rectangular blocks into which those granite masses always separate by the influence of the atmosphere. it will now be evident, that those mountains, thus resolving into separate blocks, must acquire this series of pyramidal constructions; for, in every particular mass of mountain, there must be a central part, from which the separated blocks cannot be removed, while those around, or towards the sides, are detached by the swelling water upon freezing, and separated from the more central masses which are thus the latest of being removed. it is impossible to see this series of pyramidal relics, without at the same time perceiving that manner of formation, by the gradual resolution of the solid mass of granite, as it comes to be exposed in succession to the influences of the atmosphere, which m. de saussure has termed _les ravage du temps_. but if it be in this manner, that time wastes the solid masses of this globe; and if all the solid masses of the earth have acquired their solid state by the same means, _i.e._ by heat and fusion, as is maintained in the present theory, we should find similar pyramidal mountains formed of different materials. now there can be nothing more different than masses of lime-stone and those of granite. but pyramidal mountains are equally formed of those two different materials. in plate v, under the letter b, may be seen the calcareous pyramids which are near the _col de la seigne_, and which in plate vi. are represented under the letter g. here is a view of the summit of the alps, from whence we may be allowed to draw the most important conclusions in favour of our theory. this summit is of solid granite, a mass in which there is no stratification, such as is to be perceived in all the other masses of those alpine regions. with regard again to the extent of this mass of granite, its basis is about two leagues in breadth, by at least thrice that space in length; and now we are to consider in what shape this mass of granite presents itself to our view. the summit of mont blanc, which may be considered as in the centre of this mass, is a pyramid; and this great central pyramid is surrounded by a number of other great pyramids of the same kind. the points of those pyramids are extremely lofty; and, having sides often vastly steep, if not perpendicular, those colossal pyramids rise from the icy valleys in such a shape as has given occasion to their being named _needles_. thus we find the whole space of this granite mass consisting of a mixture of icy valleys, and pyramidal rocks on which hardly any thing rests. now, these lofty rocks or pointed mountains must have been either originally formed of that shape, or posteriorly hewn out by the hand of nature, gradually wasting mountains in the course of time, and operations of the surface. if it is by the first that we are to explain the present state of things, then observation is superfluous, and our reasoning is at an end; for, when even observation should not contradict the proposition, which it actually does, it would be useless, as it can afford no data from a former state, which is supposed to have been no other than it is at present; and reasoning cannot be admitted if we have no data. therefore, if we are to reason upon the subject, we are obliged to admit, that nature must have hollowed out of the solid rock all those pyramidal mountains, and a system of inclined valleys carrying the ice from the summits. let us now reason from our principles, in order to see how far the present appearances of things would naturally result from those wasting causes acting upon a mass of granite, of a given basis and of sufficient height, during a space of time which is unlimited. we are to suppose our mass of granite without any structure except that of the veins and cutters, formed by the contraction of the solid mass in cooling. now, those separations will naturally give direction to the operation of the wasting causes, whether we consider these as chymical or mechanical. hollow tracts would thus be formed in the solid mass; in those hollow ways would flow the water, carrying the detached portions of the rock; and those hard materials, by their attrition upon the solid mass, would more and more increase the channels in which they move. thus there would be early formed a system of valleys in this rock, and among those valleys a number of central points, or summits over which no running water would carry hard materials to operate upon the solid rock over which it flows. here therefore, in the nature of things, is placed the rudiments of our needles, those colossal pyramids which acquire height gradually as the valleys widen, and whose _apices_ may arrive at an angle of a certain degree of acuteness. but what a waste of rock to have formed all those needles which we find rising from the icy valleys round mount blanc! upon the supposition that this had been the origin of those pyramidal mountains, it must be evident, that there is a _ne plus ultra_ of acuteness to which the _apex_ of a pyramid would in time arrive; and that then the decaying summit would tumble by the lump alternately, and regain the acuteness of its point. now, if this be the case, although we cannot see the process, which is too slow for human observation, we should actually find them in all the stages of this progress. but this is precisely the state in which the summits of those mountains are to be found. m. de saussure gives a view of one of those pyramids, which will serve to illustrate this subject in the most perfect manner. it is from the montanvert that this object is to be perceived. (voyages dans les alpes, vol. .). these high peaks of solid rock demonstrate the manner in which those enormous masses of mountains are degraded, and also the means which are employed by nature for that purpose; but this scene, however well represented, is too far removed, in its appearance, from the ordinary mountains of this earth, to satisfy the doubts of every reader or to generalise a principle which must be universal in the system of this earth. we therefore have occasion for a mean, by which the extreme of those alpine summits shall be generalised or connected with our low inclined plains; and, on this occasion, i will give m. de saussure's most excellent description of the breven. nothing can better suit our present purpose than the subject of this natural history; and i am persuaded that most readers will be better informed by the description of this naturalist, than they would be by their own observation. «§. . j'ai déjà plusieurs fois nommé cette montagne, qui est située immédiatement au-dessus du prieuré de chamouni, du côté du nord-ouest: elle est liée par sa base avec les aiguilles-rouges, dont j'ai aussi parlé dans le premier volume. mais sa cime est nue, isolée, arrondie sur les derrières, et coupée à pic du côté de chamouni. c'est à tous égards une des montagnes les plus intéressantes pour un naturaliste. «j'y montai pour la premiere fois en , et je ne crois pas qu'aucun naturaliste l'eût visitée avant moi; j'y retournai l'année suivante; j'y allai encore en , et j'y montai enfin pour la dernière fois en , afin de vérifier mes anciennes observations, et de me mettre en état d'en donner une description plus exacte. «§ . on peut du prieuré monter au sommet du bréven et redescendre dans le même jour, mais c'est une course pénible, car il faut au moins cinq heures pour monter, et la pente est extrêmement rapide. on peut cependant faire à mulet le premier tiers de cette montée. comme je voulus avoir le tems d'observer tout avec soin, j'y destinai deux jours, et j'allai coucher le premier jour dans un chalet, nommé _plianpra_, qui, en partant du prieuré, est aux deux tiers de la hauteur totale de la montagne. «en montant à plianpra, on fait près des trois quarts du chemin sur des débris tombés et roulés du haut de la tête du bréven. la colline même sur laquelle est bâti le village du prieuré n'est composée que des débris de cette montagne; ces débris ont débouché par une gorge que nous traversons en montant, et se versant ensuite à droite et à gauche, ils ont pris la forme d'un cône, dont le sommet est au milieu de cette gorge. les collines de ce genre et de cette forme se rencontrent bien fréquemment dans les vallées bordées par de hautes montagnes. «ces débris, qui ne viennent pas seulement de la tête du bréven, mais de ses flancs et de sa base, sont des roches feuilletées mélangées de quartz, de mica et de feldspath dans toutes les proportions imaginables. de ces différentes proportions naissent différens degrés de dureté, depuis le granit feuilleté le plus dur jusques à la roche micacée la plus tendre. «§ . les rochers au pied desquels on passe avant de gravir la montée rapide et herbée qui aboutit à plianpra, sont composés d'une roche feuilletée assez dure, dont les couches bien parallèles aux veines intérieures de la pierre, suivent la direction de l'aiguille aimantée et sont très-inclinées à l'horison. «le chalet de plianpra est situé au milieu d'une assez grande prairie en pente douce du côté de la vallée de chamouni, et dominée du côté opposé par les rocs nus qui forment les sommités de la chaîne du bréven. du bord de cette prairie, on a une très-belle vue du mont-blanc, de la vallée de chamouni et des glaciers qui y aboutissent. ces mêmes objets se présentent avec bien plus d'éclat de la cime du bréven; cependant la vue de plianpra mériteroit bien que ceux qui n'auroient pas la force ou le courage d'aller jusques à la cime, montassent du moins jusque là pour s'en former une idée. «comme je ne voulois monter sur le bréven que lendemain, j'employai le reste de la journée à observer les environs du chalet. j'examinai surtout avec soin des rochers situés à une demi-lieue au nord au-dessus du chalet, qui de loin paroissent colorés en rouge, comme plusieurs sommités de cette chaîne: c'est par cette raison qu'elle porte le nom _d'aiguilles-rouges_. «§ . je trouvai que c'étoient encore des granits veinés, mélangés de quartz, de feldspath, de mica et de fer qui colore la pierre en se décomposant au-dehors: cette teinte pénètre même quelquefois assez avant dans l'intérieur. ces rochers sont divisés par couches bien distinctes, à-peu-près verticales, et dans la direction de l'aiguille aimantée, comme celles que j'avois observées au-dessous du chalet. ces couches sont coupées par des fentes à-peu-près perpendiculaires à leurs plans, et qui sont pour la plupart parallèles à l'horison, de maniere que ces rochers se trouvent ainsi divisés en grandes pieces de forme à-peu-près rhomboïdale. les veines mêmes intérieures de la pierre sont aussi très-bien prononcées, et exactement parallèles à ses couches; observation générale et de la plus grande importance, parce qu'elle prouve que ces couches sont bien de vraies couches, et non point des fissures produites fortuitement par la retraite ou par un affaissement inégal des parties du rocher. ces veines sont dessinées sur le fond blanc de la pierre des feuillets minces de mica noirâtre; elles sont tantôt planes, tantôt ondées, mais toujours régulières et parallèles entr'elles, excepté là où il se rencontre des noeuds; encore reprennent-elles leur direction après en avoir fait le tour. comme le mica s'y trouve en petite quantité, la pierre est dure, et ne se brise qu'à grands coups de marteau. lorsqu'on l'observe de près dans sa cassure, on voit que les petites lames ou écailles de mica sont constamment couchées dans le sens des veines de la pierre. ces mêmes écailles n'ont presque aucune adhérence entr'elles, en sorte que les feuillets dont la pierre est composée, n'adhèrent entr'eux que par les points où il ne se trouve point de mica. «§ . je me demandois à moi-même, en observant cette pierre, s'il étoit possible qu'elle eût été formée dans cette situation verticale; si ces écailles incohérentes auroient pu venir s'attacher à ces murs verticaux, et si le mouvement des eaux, clairement indiqué par le tissu feuilleté de la pierre, n'auroit pas dû les détacher et les faire tomber à mesure qu'elles se formoient. je me demandois encore, si les fentes qui coupent ces feuillets, perpendiculairement à leurs plans, ne dateroient point d'un tems ou ces couches auroient été horisontales, et n'auroient point été produites alors par le poids et l'affaissement inégal des parties de la pierre. mais pour admettre cette supposition, il faudroit expliquer comment ces bancs, d'abord horisontaux, ont pu se redresser; pourquoi ce redressement a été si fréquent, si régulier, etc. etc. je réserve pour un autre tems la discussion de ces grandes questions; mais je ne crois pas inutile de faire apercevoir la liaison qu'ont avec la théorie des observations si minutieuses en apparence. «en faisant ces réflexions, je retournai au chalet de plianpra où je passai la nuit sur de la paille que j'avois fait étendre auprès du feu, parce que la soirée étoit extrêmement fraîche. «§ on commence à monter par de jolis sentiers peu inclinés, pratiqués le long d'un grand rocher semblable à ceux que j'avois observés la veille. on a ensuite le choix de monter, ou par des pentes couvertes de rocailles un peu fatigantes, ou par des gazons extrêmement rapides. ceux-ci paroissent d'abord plus agréables et moins pénibles; cependant ces gazons sont si serrés et si glissans, qu'ils en deviennent dangereux, au moins pour ceux qui n'ont pas l'habitude des montagnes. ces rocailles sont débris de roches feuilletées, semblables à celles que l'on rencontre en montant du prieuré à plianpra. «§ . b. au bout d'une heure de marche, on arrive au pied d'un rocher assez escarpé, qu'il faut escalader pour parvenir à la cime de la montagne. c'est une roche micacée, mais qui contient cependant assez de quartz pour avoir de la consistance. elle se sépare par feuillets si décidés, que sans employer d'autre instrument que mes mains, j'en détachai une dalle, qui avoit sept pieds de hauteur sur quatre de largeur, et à peine un pouce dans sa plus grande épaisseur. «j'avois quelque desir de descendre de-là au pied des grandes tables verticales qui composent la tête du bréven, pour les observer de près et comparer ainsi leur base avec leur cime; mais de cet endroit la chose est impossible, la pente est d'une telle rapidité qu'une pierre médiocrement grosse, que je mis en mouvement, roula avec beaucoup de vitesse, en entraîna d'autres, celles-ci d'autres, et elles formèrent enfin un torrent de pierres qui se précipita avec un fracas mille fois répété par les grands rochers du bréven. «comme donc je ne pouvois pas descendre, je montai par le passage ordinaire, qui est une espèce de couloir ou de cheminée ouverte, adossée à un rocher presqu'à pic, de ou pieds de hauteur. bien des curieux sont venus jusques au pied de ce passage sans oser le franchir; mais je vis en revenant qu'à un demi-quart de lieue plus au nord, on trouve un autre passage extrêmement commode, qui mène au même but, et qu'il faut par conséquent toujours préférer. «ce rocher une fois escaladé, on monte par une pente douce, sans danger et sans fatigue, jusqu'au sommet du bréven. «§ . c. en montant le long du bord, du côté de chamouni, j'eus un plaisir inexprimable à contempler les magnifiques tables de granit dont est composée toute la tête de cette montagne. car bien que les écailles du mica noirâtre dont cette roche est mélangée, soient parallèles entr'elles et lui donnent ainsi quelque ressemblance avec une roche feuilletée, cependant la quantité de quartz et de feldspath qui entrent dans sa composition, son extrême dureté, le peu de disposition qu'elle a à se fondre dans le sens de ses feuillets, la placent, sinon pour le nomenclateur, du moins pour le naturaliste, dans la classe des vrais granits[ ]; et le parfait parallélisme de ces feuillets avec les faces des grandes tables, ou des grandes divisions du rocher, démontre que ces tables sont des couches, et non des parties séparées par des fissures accidentelles.» [footnote : «la dénomination de _granit veiné_ que j'ai, à ce que je crois, employée le premier, a paru très-heureuse à quelques naturalistes, et a, au contraire, souverainement déplu à quelques autres. un de ces derniers prétend que ce que je nomme granit veiné n'est qu'un amas de gravier graniteux, et par conséquent une espèce de grès grossier. mais je voudrois que ceux qui de bonne foi pourroient croire que j'aie commis une erreur aussi grossière et aussi fréquemment répétée, observassent les granits du bréven; et j'en enverrais volontiers à ceux d'entr'eux que le souhaiteroient. lorsqu'ils verroient que les parties de quartz et de feldspath qui entrent dans leur composition, ont tous leurs angles vifs et tranchans, que ces parties sont intimement unies entre elles et empâtées les unes avec les autres, comme dans les granits en masse; que leur cohérence est aussi grande que dans ces derniers granits, et que cette roche n'en diffère absolument, comme je l'ai déjà dit, que par le parallélisme qu'observent entr'elles les lames rares de mica dont elle est mélangée: je suis persuadé qu'ils reconnoîtroient qu'elle a tous les caractères essentiels du ranit, qu'elle doit avoir la même origine, et qu'en un mot elle est au granit proprement dit, ce qu'une pierre calcaire feuilletée est à une pierre calcaire dans laquelle on ne distingue point de feuillets.»] «l'extrême régularité de ces tables achève de démontrer que ce sont de véritables couches. leurs plans qui sont ici à découvert dans une hauteur perpendiculaire de plus de pieds, sont parfaitement suivis, comme taillés au ciseau, dirigés tous comme l'aiguille aimantée, et verticaux, à quelques degrés près dont ils s'appuyent contre le corps de la montagne. on s'assure en montant que cette structure est celle de la montagne entière; on voit les profils d'une infinité de ces couches, on passe sur les sommités de ces tranches verticales, et on les voit se prolonger dans cette même direction tout au travers de la montagne. or je demande si un naturaliste qui aura observé cet ensemble et ces détails pourra regarder cette montagne comme le produit du concours fortuit de grains de sable agglutinés entr'eux. «ces tables sont coupées un peu obliquement à leurs plans par des fentes dont la plupart sont à-peu-près horizontales et d'autres trés-inclinées à l'horizon. la pierre se trouve ainsi très-fréquemment coupée en parallélépipèdes obliquangles. ces mêmes fentes rendent raison, d'une observation que j'avois faite en . en examinant avec une bonne lunette, depuis une fenêtre du prieuré, les faces verticales des couches de la sommité du bréven, j'avois remarqué un grand dieze [illustration] bien nettement écrit sur la face de la montagne, je le vis de prés en , et je reconnus qu'il étoit formé par quatre de ces fentes qui se coupoient obliquement. «§ . la cime de la montagne est une pointe mousse, coupée à pic du côté de la vallée de chamouni et arrondie de tous les autres côtés. cette tête est entièrement couverte de débris et de blocs confusément entassé. on est étonné de trouver là ces débris, car cette cime est absolument isolée, et séparée par de larges et profondes vallées des sommités qui la surpassent en hauteur: il semble que ces débris n'aient pu tomber que du ciel; mais quand on les examine avec soin, on voit qu'ils sont du même genre de pierre que la montagne elle même; et que tous leurs angles font vifs, leurs faces planes et leur forme souvent rhomboïdale. on reconnoît donc par là que les parties supérieures de la montagne, qui sont plus exposées aux injures de l'air et qui ne sont pas assujetties par des masses situées au-dessus d'elles, se délitent et se separent. je trouvai cependant sur la cime une pierre d'une espece différente; c'étoit une roche composée de schorl noir en aiguilles, de quartz et de grenats; sa forme étoit exactement rhomboïdale. mais ce genre de pierre se rencontre assez souvent en filons dans les roches feuilletées et dans les granits veinés; il est donc vraisemblable que le filon auquel ce fragment avoit appartenu s'est détruit avec la partie supérieure du rocher, du moins n'en ai-je pu trouver aucun indice dans la partie solide de la montagne. «l'admirable régularité des couches de cette cime élevée mérite l'attention des amateurs de la géologie, et la vue qu'elle présente dédommageroit seule de la peine d'y monter. «§ . mon but principal dans la premiere course que je fis au bréven étoit de prendre de là une idée juste des glaciers de la vallée de chamouni, de leur forme, de leur position, et de l'ensemble des montagnes sur lesquelles ils sont situés. comme cette montagne est postée à-peu-près au milieu de la vallée de chamouni, en face du mont-blanc et vis-à-vis des principaux glaciers qui en descendent, c'étoit certainement un des meilleurs observatoires que l'on pût choisir dans cette intention. j'y montai par le jour le plus beau et le plus clair; c'étoit mon premier voyage dans les hautes alpes, je n'étois point encore accoutumé à ces grands spectacles; en sorte que cette vue fit sur moi une impression qui ne s'effacera jamais de mon souvenir. «on découvre tout-à-la-fois et presque dans un seul tableau les six glaciers qui vont se verser dans la vallée de chamouni, les cimes inaccessibles entre lesquelles ils prennent leur naissance; le mont-blanc surtout, que l'on trouve d'autant plus grand, d'autant plus majestueux, qu'on l'observe d'un lieu plus élevé. on voit ces étendues immenses de neige et de glaces, dont, malgré leur distance, on a peine à soutenir l'éclat, ces beaux glaciers qui s'en détachent comme autant de fleuves solides qui vont entre de grandes forêts de sapins, descendre en replis tortueux, et se verser au fond de la vallée de chamouni; les yeux fatigués de l'éclat de ces neiges et de ces glaces se reposent délicieusement ou sur ces forêts, dont le verd foncé contraste avec la blancheur des glaces qui les traversent, ou dans la fertile et riante vallée qu'arrosent les eaux qui découlent de ces glaciers.» our object at present is not to see the degradation of that great mass of granite out of which have been hewn, by the hand of time and influences of the atmosphere, these lofty pyramids which surround mont-blanc; it is to see the degradation of that immense mass of vertical or highly inclined strata, out of which that great mass of granite rises; and it is to understand the conical and rounded forms which are to be perceived more or less in all the inferior mountains, where apparently the degradation has come to a stand, and where the surface is actually employed in vegetation, or in maintaining the system of living bodies in this world. how high those vertical strata may have been erected, or how much may have been wasted of that mass in forming the mountains and their valleys, is a question which it is impossible to resolve: it is evident, however, that this quantity must have been very great. in the mont-rosa we find those strata at present in the horizontal situation, as high as the summits of those granite pyramids that overlook the mass of vertical strata which we are now considering; and, in those mountains of rosa, the valleys are most profound. it is therefore most reasonable to suppose, that the mass out of which the breven and all the other mountains had been formed, was once as high, at least, as the summit of mont-blanc. it is altogether inconceivable, that this mass of vertical and horizontal strata could have been formed, either originally, or by any mineral operation, into the present shape of things; therefore, we must look out for another cause. let us now suppose them degraded by the hand of time, and all their moveable materials transported in the floods; in what state would they be left for our examination?--here is a question that must decide the theory of those mountains; for, if it is not possible to conceive the present appearances as arising from any other cause than this gradual degradation which we see operating at present, we must conclude that this is the system of nature established for the purpose of this world. but this is the very state in which they are found; every where the solid parts are going into decay, and furnishing those heaps of earth and stones that form the slopes by which we ascend from step to step. wherever earth and stones may lie, there they are found to form a bank for vegetation; whenever these loose materials are carried away to a lower; station, the more solid parts above are still decaying in order to furnish more. there is not one step in all this progress, (of the summit of the solid mountain forming earth and stones, and travelling to the sea) that is not to be actually perceived, although it is only _scientifically_ that man, who reasons in the present moment, may see the effect of time which has no end. the summit of the granite pyramids of mont-blanc, the summit of the breven, that of the saleve[ ], and of every little hillock upon the surface of the earth, attest this truth, that there is no other natural means by which this end may be attained. it is true, indeed, that geologists every where imagine to themselves great events, or powerful causes, by which these changes of the earth should be brought about in a short space of time; but they are under a double deception; _first_ with regard to time which is limited, whereas they want to explain appearances by a cause acting in a limited time; _secondly_, with regard to operation, their supposition of a great _debacle_ is altogether incompetent for the end required. how, for example, accumulate the _debris_ of the breven, as we have now seen, upon the summit of that mountain, by the force of running water? but this is only one of a thousand appearances that proves the operations of time, and refutes the hypothesis of violent causes. [footnote : see part ii. chap. .] from the top of those decaying pyramids to the sea, we have a chain of facts which clearly demonstrate this proposition, that the materials of the wasted mountains have travelled through the rivers; for, in every step of this progress, we may see the effect, and thus acknowledge the proper cause. we may often even be witness to the action; but it is only a small part of the whole progress that we may thus perceive, nevertheless it is equally satisfactory as if we saw the whole; for, throughout the whole of this long course, we may see some part of the mountain moving some part of the way. what more can we require? nothing but time. it is not any part of the process that will be disputed; but, after allowing all the parts, the whole will be denied; and, for what?--only because we are not disposed to allow that quantity of time which the ablution of so much wasted mountain might require. chap. x. _the theory illustrated with a view of the valleys of the alps._ such is the summit of the alps, a body wasting by the influence of the elements, slowly changing, but in actual decay. this mass of granite is arrived at such a perfect state of degradation as leaves no trace of its original shape or height, from whence we might compute the quantity which has been lost, or time which had flowed in bringing about that event. we are now to take a view of the valleys that are formed at the same time that the mountains are degraded. to the valleys of ice succeed those formed by water upon the same principle by moving the hard materials procured from the summits. let us now begin at the bottom of one of those fertile valleys, and ascend, tracing the marks of time and labour in those operations by which the surface of the earth is modified according to the system of the globe. (m. bourrit[ ], _nouvelle description des alpes_.) «saint-maurice est entre le rhône et une montagne; «quoique la situation de saint-maurice paroisse l'exposer au malheur d'être un jour ensevelie sous les ruines des montagnes, cependant on ne vit pas ici avec moins de sécurité qu'ailleurs: ce qu'il y a de plus à craindre, c'est la submersion du pays; ce malheur pourrait arriver si l'une ou l'autre des montagnes qui forment la gorge, venoit à tomber soit par un tremblement de terre, soit par des affaissemens considérables: cette gorge étant étroite, le rhône ne pourroit plus s'écouler il s'étendroit nécessairement au large, bientôt toute la vallée jusqu'à martigni, sion même, rentreroit sous les eaux qui l'ont autrefois couvert, et tout ce pays ne formeroit plus qu'un lac, à moins que le rhône ne se fît jour sous les rochers renversés, comme il passe au travers de ceux qui semblent lui disputer le passage à cinq-lieues au-dessous de genève.» [footnote : m. bourrit, etc.] «avant de pénétrer dans le vallais, il convient d'en donner une idée générale: il forme cette partie des alpes connue sous le nom d'alpes pennines; il contient non-seulement les plus hautes montagnes des alpes, mais encore la plus longue vallée qui il y ait en europe, puis qu'elle a trente-quatre lieues depuis saint-maurice jusqu'à-la source du rhône, qui la traverse dans toute cette étendue: sa largeur est depuis demi-lieu jusqu'à une lieue et demie; sa direction suit le soleil. outre cette vallée, il y en a d'autres qui y viennent aboutir dans diverses directions: celle-ci sont enclavées dans les deux chaînes de montagnes qui bordent la grande vallée; quelques-unes remontent à quatre lieues et même à six, dans les sinuosités que forment les rochers qui bordent les deux côtés du fleuve.» to give an idea of these valleys which proceed to the icy tops of mountains, or to the high valleys of ice, i shall transcribe some descriptions of this country from the tableaux de la suisse discours, etc. page . «_route au mont-saint bernard._ «on passe par martigny pour aller au mont du grand saint-bernard; cette ville est un dépôt pour les marchandises qui vont et viennent d'italie. le château à côté de cette ville est situé sur des rochers calcaires qui bordent la drance dans cette partie; ce torrent prend sa source au mont saint-bernard. on compte huit lieues de martigny à l'hospice situé sur ce mont; à une demie-lieue on commence à monter insensiblement; le chemin est beau et peut se faire en voiture jusqu'au bourg saint-pierre. «le vaste base de ces monts accumulés n'est qu'un composé des débris des montagnes supérieures; on rencontre ici des granits roulés, composés de quartz, de feld-spath, et de mica; des graviers et des sables provenant de la décomposition des granits des pierre calcaire grise, puis de grosse masses de granit arrondies, dont il seroit difficile d'assigner l'origine, puisque toutes les montagnes à portée de la vue et qui forme cette gorge sont absolument de pierres micacées par lits et par couches, ou schisteuses mêlées de gros et petits rognons, de filons et de veines de quartz; elles font en général toutes feu avec le briquet. le chemin et la drance qu'on passe et repasse plusieurs fois, occupent tout le fond de la vallée qui devient fort étroite. on rencontre des pierres schisteuses, quartzeuses et sablonneuses, seules sans mélange d'autre espèces. «saint-branchier, bon village, est situé entre des montagnes très-hautes et trés-escarpées composées des mêmes espèces des pierres schisteuses micacées que les précédentes; elles sont de couleur bleuâtre, vue en grandes masses et inclinées à l'horison; cette inclinaison suivant la même direction de ce côté ci de la drance, et les couches se correspondant l'une à l'autre, on voit que ce torrent s'y est creusé un passage. en avançant, on trouve de l'ardoise feuilletée bleue avec des veines de spath calcaire, ensuite une grande quantité de granits et de pierres calcaires roulées, sans que les montagnes environnantes changent d'espèces; les montagnes à l'est sont bien cultivées, rapportent différentes sortes de grains, avant et après avoir passé orsiére; on retrouve de l'ardoise entre ce village et liddes et les derniers granits roulés. «la drance est ici fort resserrée et trés encaissée; ce n'est pas sans frémir qu'on s'apperçoit, quand on est sur deux morceaux de bois jetés d'une roche à l'autre, appellés ici pont, qu'on a un gouffre de plus de trois cent pieds au dessous de soi, il faut être sur cette espèce de pont pour s'en apercevoir et distinguer les différents sinuosités tracées sur chaque côté de cette roche du haut jusqu'en bas; ce sont autant de preuves des différentes hauteurs où l'eau a passé avant de parvenir à sa profondeur actuelle. «la dernier village qu'on rencontre, avant d'arriver au saint-bernard, est le bourg saint-pierre, on mont insensiblement jusqu'à ce village, et on ne peut plus se servir de voitures pour aller au-delà. les montagnes sont plus rapides, il n'y a plus de chemin fait, et on n'en peut point pratiquer, moins a cause de la quantité des rochers dont toute cette partie est couverte que par la difficulté de les entretenir ou de les renouveler chaque année, parce que les torrens et les avalanches les detruiroient; de plus on ne pourroit y travailler que trois ou quatre mois de l'année, les huit ou neuf autres mois le pays, au dela du bourg, étant presque toujours couvert de neige. la truite ne remonte pas au-delà du bourge saint-pierre, elle se trouve arrêtée par les cascades et chutes trop considérables de la vassorée qui va se jetter dans la drance. ce torrent sort encaissé et resserré dans le lit qu'il s'est creusé, provient d'un glacier qu'on rencontre en montant le saint-bernard qui porte le même nom. l'entrée du valais est fermée et défendue de ce coté par le lit de la vassorée; c'est le fosse le plus profond et le plus escarpé qui existe. des ouvrage crénelés et une porte sont placés à l'entrée du bourg saint-pierre, nous avons donné un dessin de la chute de ce torrent, on voit le travail des eaux dans le rocher qu'il a miné et où il s'est ouvert un passage. «on compte trois lieues de ce bourg à l'hospice, sur le haut du saint-bernard; c'est le passage le plus fréquenté pour communiquer du bas-vallais en italie par le piémont et la vallée d'aost; le transport des marchandises ne se fait qu'à dos de mulets et de chevaux; c'est du produit de ces transports que vivent la plupart des habitans qui sont des deux côtés de ce mont; celui des fromages, qui est la principale production de ces hautes alpes, fait le plus fort article. on ne rencontre sur cette route que des rochers entassés les uns sur les autres, entre lesquels on passe par mille détours, en suivant les petits vallons qu'ils forment. des torrents des eaux y roulent et s'y précipitent de tous côtés; on voit dans ces bas, de bois de sapins mêlés de quelques pins et puis des mélèzes; ils diminuent insensiblement, leurs végétation est moins vigoureuse, les arbres sont plus rares les derniers qu'on rencontre sont des mélèzes à une heure de saint-pierre. plus loin, on ne voit plus que des buissons bas et rabougris; au bord de quelque ruisseau ou torrent ce sont des aulnes ou vergnes; le dernier arbrisseau que nous avons vu, entre les mélèzes et les aulnes, est un sureau sans fruit. les pâturages, l'herbe et le gazon suivent la même progression. ce n'est-que dans quelques endroits, d'où les eaux n'on pas entraîné une restant de terre végétale, qu'il se voit un gazon fin, menu et serré; de petites fleurs, aussi bases que ces gazons, nuancées des plus belles et des plus vives couleurs, y forment des groupes de la plus grande beauté; des mousses non moins curieuses que variées, couvrent et colorent quelques parties de rochers; le reste n'offre à l'oeil que d'énormes masses de rochers, entrecoupés de fentes, de crevasses; des pierres culbutées et amoncelées dans les fonds, qui font en partie couverts de neïge. «a une demie lieue de l'hospice dans une vallon assez large pour une pareille hauteur, nommé les envers des foireuse, on rencontre une énorme quantité de pierre roulées qui remplissent presque tout le haut de ce vallons. cet amas de pierres provient des glaciers et des hauteurs qui descendent du mont-velan, qui est la partie la plus élevée du groupe de montagnes, qui forment le grand saint bernard. là sont des neiges et des glaciers de cette partie, fournit aussi la drance qui va se jetter dans le rhône au dessous de martigny. on ne voit de ces pierres roulées qu'en cet endroit, elles viennent directement des glaciers, elles ont été charriées par les eaux qui en viennent, et ne peuvent avoir pris leur forme que par les même causes, dont nous avons parlé ci-devant dans l'observation faite en savoie sur les pierres roulées; elles sont toutes, ainsi que les rochers au-dessus, d'ou-elles proviennent, composées de parties micacées-argilleuses, plus ou moins mêlées de partie de rognons, de veines et de filons de quartz, par lits et par couches irrégulières, plus ou moins épaisses. les parties micacées de ces pierres sont variées de différentes nuances, tirant sur le gris, le bleu, le verd, et le jaune; ces nuances sont quelquefois mêlées. tous les rochers composans ce côté de montagne tourné au nord, sont de la même espèce. nous n'y avons pas vu un seul granit, c'est-à-dire, une pierre composée de petites masses irrégulières de quartz, mêlées et agglutinées, avec des parties micacées argilleuses, et quelquefois mélangés de feldspath. parmi ces pierres, il y en a quelques-unes provenant du même filon, qui contiennent de la pyrite cuivreuse dans un filon de quartz. «nous avons dit precedement que c'étoit entre orfière et liddes que nous avions vu des derniers granites roulés, on n'en rencontre plus dans toute le reste de la route jusqu'au haut du mont saint-bernard. les rochers, qui dominent ce sommet, ne sont pas composes de granites, et quoiqu'on ne puisse aborder jusqu'à leurs plus grands élévation, on peut juger de leurs espèces, par les masses qui s'en précipitent. «(page .) malgré la chaleur qu'il avoit fait le jour de l'arrivée au saint-bernard, la nuit fut froide; le lendemain ( juillet) le haut de la montagne étoit enveloppé de nuages épais, mais tranquilles, il n'y avoit point d'agitation dans l'air on assuroit qu'il faisoit beau au-dessous de ce sommet; nous fûmes visiter le revers meridional de la montagne qui conduit au val d'aost; après une demie heure de marche, nous fumes hors de cet atmosphère sombre et humide, le soleil étoit chaud, le ciel pur et serein: on voyoit dans le lointain les sommets des plus hautes montagnes enveloppés dans les nuages comme le saint-bernard: les sommets les plus à portée étoient découverts et éclairés par le soleil; ces rochers terminés en pointe, en pyramides et en aiguilles, sembloient s'élancer dans la région pure de l'éther: des vallons profonds, des écueils, et des précipices effrayants les entouraient. toutes ces masses sont, comme dans la partie opposée de la montagne, des pierre schisteuses, argilleuses et micacées: le plupart schisteuses, c'est-à-dire par feuillets, par lits ou par couches différemment inclinées, le toute mêlé de veines et de parties quartzeuses, de couleurs variées, mais les verdâtres dominent: il y a de plus sur la hauteur de ce revers des masses et des blocs prodigieux, sans mélange, de quartz blanc et grenu à sa superficie, lesquels, au premier coup-d'oeil, paroissoient être de marbre de carare; à quelque distance c'est un chaos immense de blocs de pierres de toutes grandeurs, jetés, culbutés, entassés dans la plus grand confusion; c'est la même espèce de pierre micacée; il faut que des sommets, des rochers prodigieux se soient écroulés pour avoir produit un pareil désordre qui ressemble à la destruction d'un mond. «(page .) on trouve aux environs du couvent quelques schistes argilleux ou ardoises grises feuilletées détruites à moitié. on ne voir nulle part de ces ardoises sur pied ou formant des masses attachées au sol; il faut que les couches ou les lits de ces ardoises, qui avoient été formés et placés sur ces hauts, ayent été détruits et renversés par le temps. «enfin toute cette montagne, une des plus hautes des alpes poenines, qui conserve des neiges et de glaces permanentes, est composée en général de pierres et de roches schisteuses, dont les couches et les lits sont plus on moins sensibles et inclinés, et d'une grande dureté. leurs parties constituantes sont un mica argilleux dont les lames ou les parties sont plus ou moins grandes et brillantes et diversement colorées: elles sont traversées de filons et de veines mêlés de rognons et de globule de quartz ordinairement blanc, quelquefois vitreux, transparent, opaque ou grenu: nous n'y avons vu des granits que sur le penchant de la montagne; ils y étoient isolés et roulés. quelqu'un qui aura plus de temps, plus de loisir, découvrira peut-être d'où ces masses proviennent[ ].» [footnote : m. de saussure, in his d volume of voyages dans les alpes, has shown the origin of these travelled granites, and traced the way by which they have come.] we have here a picture of one of those valleys which branch from, or join the main valley of the rhône. in this subordinate valley, there is the most evident marks of the operations of water hollowing out its way, in flowing from the summits of the mountains, and carrying the fragments of rocks and stones along the shelving surface of the earth; thus wearing down that surface, and excavating the solid rock. on the summit of the mountain, again, there is an equal proof of the operation of water and the influences of the atmosphere continued during a long succession of ages. it is impossible perhaps to conjecture as to the quantity of rock which has been wasted and carried away by water from this alpine region; the summits testify that a great deal had been above them, as that which remains has every mark of being the relicts of what had been removed, and moved only by those operations which here are natural to the surface of the earth. let us now abstract any consideration of that quantity above the summits of those mountains, as a quantity which cannot be estimated; and let us only consider all the cavity below the summits of those ridges of mountains to have been hollowed out by those operations of running water which we now have in view. in taking this view of the mountains on each side which supply the water of the rhône, what an immense quantity of stones, of sand, and fragments of rock, must have travelled in the bed of that river, or bottom of that valley which receives the torrents coming from the mountains! the excavation of this great valley, therefore, will not be found any way disproportionate to that which is more evident in the branches; and, though the experience of man goes for nothing in this progress of things, yet, having principles in matter of fact from whence he may reason back into the boundless mass of time already elapsed, it is impossible that he can be deceived in concluding that here is the general operation of nature wasting and wearing the surface of the earth for the purposes of this world, and giving the present shape of things, which we so much admire in the contrast of mountains and plains, of hills and valleys, although we may not calculate with accuracy, or ascribe to each particular operation every individual appearance. with a view to corroborate what has been here alledged of the valley of the rhône, i would beg leave to transcribe still more from the same author. from the immense masses of horizontal strata remaining upon both sides of the valley of the rhône, with a face broken off abruptly, we shall find the most perfect evidence of that which had been carried away in the course of time, and in the forming of those valleys. «(page .) route au bains de loiche. nous quitterons un moment les bords du rhône pour visiter les bains de loiche, afin de ne pas revenir sur nos pas. de sierre on passe par claré et salge, en laissant le rhône sur la droite; tout ce terrain est calcaire et fort pierreux. a faren (villages qui ne font point sur les cartes) on commence à monter la montagne de faren; le chemin est fort rapide et mauvais, et dure une bonne heure et demie; on trouve sur le haut de cette montagne de blocs de granit composés de quartz, de feld-spath, et de mica, d'où viennent-ils? on ne voit que des roches calcaires et point de montagne plus élevée au-dessus; on passe par un bois de pins, on parvient enfin à un escarpement à pic, dont on n'a point d'idée pour la hauteur; on reste stupéfait de voir le gouffre qu'on a devant soi, et on ne prévoit pas trop comment on parviendra dans ce fond, où la vue a peine à distinguer la dala, gros torrent qui y précipite ses eaux. on a taillé à grands frais un sentier tortueux dans cette roche toute calcaire; on a eu soin de garnir le coté scabreux du sentier avec des pierres ou des garde fou, pour rendre ce passage moins effrayant; ces précautions ne peuvent guérir de la crainte de voir tomber d'énormes quartiers de rochers suspendus au-dessus de soi, ils sont fendus et crevassés partout, et menacent de se précipiter à chaque instant; on ne peut même s'empêcher de remarquer qu'il y en a qui sont tombés nouvellement! ce sont des mineurs tiroliens qui ont fait cet ouvrage, ainsi que le passage du mont-gemmi. «quand on est descendu au tiers environ de cet énorme fond, on passe sur les décombres de cette vaste montagne, et par un bois de pins et de sapins; la vue ne perce pas dans ce fond ténébreux, on entend plutôt le bruit du torrent qu'on ne l'apperçoit. ayant eu occasion de voir et d'examiner par la suite ces bas et le pied de cette étonnante montagne calcaire, nous avons vu dans plus d'un endroit qu'elle pose, et que ces fondements sont un lit de schistes argilleux ou d'ardoises feuilletées sans mélange, que ce lit est détruit et se détruit dans différens endroits, qu'il est incliné et affaissé dans d'autres, et que c'est la destruction qui a occasionné la chute d'une partie de cette montagne; elle est par-tout à pic de ce côté, et a subi successivement ces renversements qui paroissent plus anciens les unes que les autres, car ces débris sont plus ou moins couverts de bois, d'arbres, et de productions végétales. «on continue la route à mi côte au travers de ces débris. le sommet de ces montagnes éclairés par le soleil, étoit peint de rouge, de jaune, de blanc, de bleu, et de noir, dans les endroits où les eaux avoient coulé par-dessus, ils ressemblent de loin à des murailles, des tours, des forts, et des fortifications de différentes formes placées pour se défendre contre des ennemis qui viendroient par les airs. les neiges qu'on apperçoit dans différents endroits, produisent des chutes d'eau, des cascades, dont partie se réduit en vapeurs avant d'atteindre le bas: le haut des montagnes qu'on voit de l'autre côté de ce vallon, est également calcaire, elles sont plus basses, couverts d'arbres et de sapins; au lieu que celles dont il est question sont nues et arides; elles sont le séjour des neiges et sont partie de la gemmi. «une de plus haute montagnes du vallais, et située sur une terrain très-élevé, est la gemmi; elle fait partie de la grande chaîne qui sépare le canton de berne du vallais. elle est remarquable, à cause de l'importance du chemin qu'on y a pratiqué, des grandes difficultés qu'il a fallu surmonter, et qu'elle est la seule communication entre les deux cantons. nous parlerons de ce chemin, après avoir décrit la nature de ce prodigieux rocher. la gemmi est la partie la plus haute de cette chaîne qui commence aux galleries; elle est en general calcaire. on commence a monter insensiblement en sortant de loiche; on traverse beaucoup de pâturages; on voit quelques champs de seigle qui étoient encore sur pied et à moitié verts, des bosquets et de petits bois de sapins. des masses considérables des rochers, des monceaux de pierres entassées descendues des hauteurs, couvrent cette superficie qui devient d'autant plus rapide qu'on approche plus du pied du rocher: cette pente qui est au pied de l'escarpement et de toutes les autres montagnes, est formé des pierres et des sables qui tombent des hauts et produisent, à la longue, des talus formes en pain de sucre, adosses contre les parties escarpées; les plus grosses pierres roulent et se précipitent plus bas, servent de point d'appui aux nouveaux matériaux qui s'y arrêtent, augmentent la hauteur des talus, en élargissant les basis, et finissent par devenir des montagnes très considérables qui ont augmenté en raison de la quantité des débris qu'ont pu fournir les parties plus élevées; c'est ce qu'on nomme montagnes de troisième formation, composées des ruines de celles qui dominent ces talus; ces éboulemens sont ordinairement plus fertiles, plus couverts de végétaux, d'arbres et de forêts, sur-tout s'ils sont composés de différentes espèces de débris. nous avons déjà vu que les montagnes calcaires sont elles-mêmes assises sur des couches et des lits d'ardoise ou de schiste, qui, par l'arrangement de leurs feuillets et de leurs couches, paroissent aussi avoir été arrangés et formés successivement; quelle est donc la base primitive sur laquelle sont appuyées et reposent ces masses qui étonnent l'imagination, à quelle profondeur faudra-t-il l'aller chercher? si nous concevons la formation et la manière dont se sont accrues et élevées ces troisièmes montagnes, pouvons-nous imaginer comment se sont arrangées celles qui sont si élevées au-dessus d'elles, ce tout que rien ne domine. c'est en examinant en considérant ces grands spectacles que ces réflections nous viennent; nous nous arrêtons, pour continuer à décrire ce que nous avons vu et remarqué, qui est la tâche que nous nous sommes imposée. «en arrivant au pied de l'escarpement, le premier objet qui frappe la vue, ce sont des bancs de schistes ou d'ardoises bleuâtres, mêlés de larges filons de quartz qui forment la base, et les fondemens sur lesquels est élevé ce mur de pierres calcaires. car cette roche est élevée de même à pic; ce lit d'ardoises est un peu incliné vers le couchant, ainsi que tout ce qui repose dessus; la destruction de ce lit a causé, ainsi qu'aux galeries, la chute des rochers supérieurs, et leur a occasionné cet à-plomb. avant ces éboulements, ces couches schisteuses devoient être découvertes à une grande hauteur, être exposées aux injures du tems et des saisons, se détruire et se décomposer plus aisément. peut-être que l'enveloppe calcaire les couvroient entièrement, et que ces schistes n'ont commencé à se détruire qu'après la ruine de la pierre calcaire. actuellement ces schistes sont enterrés et couverts; ce n'est qu'en peu d'endroits qu'on les apperçoit; appuyés soutenus et couverts par ces immenses débris en talus, ce sont des contre forts qui les aiderons à supporter plus longtemps les prodigieuses masses sous lesquelles ces schistes sont ensevelis. nous allons placer par ordre les différentes substances, telle qu'elle se présentent en montant. « . base de schiste ou d'ardoise feuilletée bleuâtre, traversé, de larges filons de quartz. on ne voit, on ne peut estimer son épaisseur dont partie est enterrée. « . immédiatement dessus pose la pierre calcaire, elle est d'une grain fin, serré, couleur grise-jaunâtre, ainsi que toute le reste. « . des filons de différentes épaisseurs, d'un spath calcaire jaunâtre. « . quelques petits filons ou renules de schiste pur. « . de la pierre calcaire d'un grain plus grossier. « . d'autres couches d'un grain plus fin. « . couches de pierres calcaires mêlées d'une quantité suffisante de sable pour faire feu avec le briquet, sans cesser de faire effervescence avec les acides. « . de petits filons ou couches ondoyantes de spath. « . de la pierre calcaire dans laquelle sont déposés des espèces de noyaux oblongs, quelques fois par couches, mais sans suite, composés d'un sable fin de couleurs grisâtre, plus blanc que la pierre calcaire, très-durs, faisant feu au briquet, et sans effervescence avec les acides. « . on retrouve encore des couches minces sablonneuses mêlées de parties calcaires. « . d'autres de pierre calcaire compacte et d'une épaisseur considérable. « . alternativement de moins compactes. dans l'une de ces couches il y a de la pyrite vitriolique décomposé, qui teint en jaune les parties du rochers sur lesquels a flué la décomposition martiale. « . quelques filons de spath jaunâtre, entremêlés de veines de schiste pur, ne faisant pas effervescence. « . de la pierre calcaire. « . des schistes mêlés de parties calcaires. « . de la pierre calcaire pure. « . de larges filons de spath calcaire jaunâtre mêlés de quartz, faisant feu au briquet, et une peu d'effervescence. « . de la pierre calcaire pure grise, plus foncée que dans le bas. « . des couches calcaires jaunâtres. « . enfin tout le haut n'est que pierre calcaire grise et dénaturée. cette partie supérieure du monte est fort étendue. tout ce qui est sur le local qui va en pente assez douce vers le milieu, n'a pas été assujetti à de roulis et à des frottemens, il n'y a que la longueur du tems qui l'ait dégradé, et lui ait imprime le caractère de la vétusté. on ne voit que des pierres calcaires, elles sont remplies de trous, de fentes, et de crevasses; beaucoup, paroissent poreuses comme de la la pierre ponce grossière; le séjour des neiges des eaux, la gelée, et l'intempérie des saisons a tout fait. on voit de tous côtés que l'eau s'y infiltre et s'y perd. l'arrangement de cette espèce de pierre par couches, facilite l'entrée des eaux dans l'intérieur de la montagne pour aller donner naissance à des sources, à des torrents, et quelquefois à d'assez fortes rivieres qui sortent du pied de ces montagnes calcaires; lors de la fonte des neiges, l'eau ne se verse point des sommets de ces sortes de montagnes comme de dessus les autres espèces de rochers qui absorbent moins les eaux. dans le milieu de ce haut il y a un petit lac d'un grand quart de lieue de long de forme ovale, ou se rassemblent les eaux des neiges fondues; il n'y a point d'issues à ce lac, ses eaux sont absorbées, et se perdent dans l'intérieur de la montagne; il n'y avoit que peu de glace alors sur ce lac, mais il y avoit encore beaucoup de neiges aux environs; un glacier est sur la droite, se prolonge et va fermer le sommet du vallon où est loiche; c'est le même glacier qu'on apperçoit derrière les sources chaudes. deux aiguilles de rocher en cône, fort hautes s'élèvent au-dessus du sommet; elles sont toujours couvertes de neiges: leur ressemblance et leur proximité a donné le nom de gemmi jumeaux, à cette montagne--on voit à ses pieds à une profondeur immense le village de loiche, qui paroît être tout au pied du rocher; il faut cependant une grand heure et demie pour s'y rendre, tant la hauteur diminue le point de perspective. le chemin qui est pratiqué dans ce rocher, y a été par-tout taillé; il le contourne certains endroits, dans d'autres il est creusé de façon qu'il forme une voûte couverte, et qu'on a le rocher suspendu au-dessus de soi. il est rare de trouver l'occasion de pouvoir examiner de détailler avec autant de facilité une montagne d'une pareille hauteur. a compter des galleries jusqu'aux glaciers de la gemmi, ces rochers perpendiculaires et à pic ont plus de trois lieues d'étendue; ils diminuent en hauteur à mesure que le pays s'élève, et se confond dans les plus hautes alpes, qui sont surmontées d'autre masses de rochers. «de l'autre coté du vallon, et vis-à-vis des montagnes qui forment celles de la gemmi, est la montagne du midi, séparée par la dala, torrent qui vient du glacier à la tête du vallon, dont les eaux paroissent avoir creusé le lit étroit et profond. cette montagne est calcaire comme la gemmi, et paroît en avoir fait partie: je n'ai pu vérifier nulle part si elle étoit posée sur des schistes: tout est dans un grand bouleversement sur sa pente qui est fort rapide. a environs trois quarts de lieue des bains, un sentier fort difficile, qui passe sur les décombres de cette montagne et dans des bois de sapins fort obscurs, conduit par un pente fort rapide a un rocher perpendiculaire, comme sont presque tous ceux du canton on y trouve des échelles appuyées contre; on parvient à la première, en grimpant par les avances et les saillies du rocher; d'autres roches facilitent le moyen d'arriver à la seconde; on trouve ainsi sept échelles dont quelques-unes sont fort hautes, et par lesquelles on se guide au sommet de ce rocher; on est bien surpris d'y trouver un terrain en pente, où il y a des champs labourés et des vignes qui entourent le village d'albinien, dont les habitans ont placé ces échelles pour raccourcir le chemin qui conduit à loiche, où ils vont vendre leurs denrées. «nous quittons les bains de loiche pour nous rapprocher du rhône: on repasse par inden, on ne trouve ensuite que des pierres, des rochers, des escarpemens; c'est un chemin des plus mauvais jusqu'au bourg de loiche; c'est pour éviter ce chemin qu'on a fait celui des galleries. le bourg de leuck, ou loiche, est un des principaux endroits du vallais, bâti en pierres, dans une position fort élevée et très-forte; l'art avoit encore ajouté anciennement à la force de son assiette, il y a encore d'anciens forts et des tours; toute cette hauteur est calcaire; on a la plus belle vue de ce lieu, elle s'étend sur tout le bas vallais jusqu'au dela de martigny; nous avons donné une foible idée de cette vue, avant d'arriver aux bains de loiche, car les expressions manquent pour rendre ces grands tableaux. un spectacle bien intéressant pour ceux qui étudient les changemens qui arrivent journellement à la surface du globe, est la vue du kolebesch, montagne fort élevée en face du bourg de leuck, et de l'autre côté du rhône; cette montagne est calcaire ainsi que la chaîne sur la rive gauche du rhône, du moins la partie avancée qui forme le vallon où coule ce fleuve. des chutes, des éboulemens y ont produit de grands changemens; les eaux et les torrens qui viennent des parties élevées, ont entraîné ces débris, les ont déposés aux pieds de la montagne, et en ont formé une colline qui a plus d'une demie-lieue jusqu'au rhône, et plus d'une grande lieue de large, en forme circulaire; elle s'étend vers le haut et le bas vallais; la partie supérieure est couverte de prés et des pâturages; celle du côté du bas vallais est couverte d'une forêt; elle va en pente douce; la grosseur des arbres prouve combien la formation de ce terrain est ancienne. depuis la consolidation de ce terrain des torrens nouveaux y ont creusé un ravin large et profond, par lequel s'écoulent actuellement les eaux des montagnes, et les pierres qu'elles en arrachent. le rhône mine et emporte le pied de cette colline qui resserroit son cours, avec ces matériaux il va plus loin former des atterrissemens composés des matières les plus pesantes; les parties les plus fines le limon suspendu dans ces eaux servent ensuite à couvrir les anciens atterrissemens, au moyen desquels ils deviennent susceptibles de toute espèce de végétation; ses eaux finissent de s'épurer dans le lac leman, d'ou il sort clair et limpide, ainsi que toutes les rivieres qui sortent des lacs jusqu'à ce que d'autre torrens, tombant des montagnes, viennent les troubler de nouveau.» here is a most satisfactory view of the structure of this country on each side of the rhône; strata of lime-stone and schisti, almost horizontal or little inclined, compose the mountains from their most lofty summits to the deepest bottom of those valleys. such mountains cannot have been formed in any other manner than by the waste and degradation of their horizontal strata; consequently, here we are certain, that, from the summit of the gemmi to those upon the other side of the rhône, all the solid substance had been hollowed out by water. thus were formed the valleys of the rhône, the dala, and a multitude of others. m. de saussure has given us a description of a tract of alpine country of the same kind with that of the _vallais_ now considered, so far as the strata are here in a horizontal position, instead of that highly inclined situation in which those primary bodies are commonly found. it is the description of mount-rosa journal de physique, juillet . here the same interesting observation may be made with regard to the immense destruction which must necessarily have taken place, in the elevated mass of solid earth, by the dissolving or wearing power of running water; and this will be clearly explained by the formation of those mountains and valleys, which, while they correspond with mountains and valleys in general, have something particular that distinguishes them from most of the alps, where the strata, being much inclined, give occasion to form ranges of peaks disposed in lines according to the directions of the inclined strata. here on the contrary, there being no general inclination of the strata to direct the formation of the peaks, they are found without any such order. i shall give it in m. de saussure's own words. «en effect toutes les hautes sommités que j'avois observées jusqu'à ce jour sont ou isolées comme l'etna, ou rangées sur des lignes droites comme le mont-blanc et ses cimes collaterales. mais là je voyois le mont rose composé d'une suite non-interrompue de pics gigantesques presqu'égaux entr'eux, former un vaste cirque et renfermer dans leur enceinte, le village de macugnaga, ses hameaux, ses pâturages, les glaciers qui les bordent, et les pentes escarpées qui s'élèvent jusqu'aux cimes de ces majestueux colosses. «mais ce n'est pas seulement la singularité de cette forme qui rend cette montagne remarquable; c'est peut-être plus encore sa structure. j'ai constaté que le mont-blanc et tous les hauts sommets de sa chaîne sont composés de couches verticales. au mont-rose jusqu'aux cimes les plus élevées, tout est horizontal ou incliné au plus de degrés. «enfin il se distingue encore par la matière dont il est construit. il n'est point de granits en masse, comme le mont-blanc et les hautes cîmes qui l'entourent; ce sont des granits veinés et des roches feuilletées de différens genre qui constituent la masse entière de cet assemblages de montagnes, depuis bases jusqu'à ses plus hautes cimes. ce n'est pas que l'on n'y trouve du granit en masses, mais il y est purement accidentel, et sous la forme de rognons, de filons, ou de couches interposées entre celles des roches feuilletées. «on ne dira donc plus que les granits veinés, le _gneiss_ et les autres roches de ce genre, ne sont que les débris des granits rassemblés et agglutinés au pied des hautes montagnes, puisque voilà des roches de ce genre dont la hauteur égale à très-peu-près celle des cimes granitiques les plus hautes connues, et ou l'on ferois bien embarrassé à trouver la place des montagnes de granit dont les débris out pu leur servir de matériaux; sur-tout si l'on considère la masse énorme de l'ensemble des murs d'un cirque tel que celui du mont-rose. en effet, ce seroit une hypothèse inadmissible que de supposer, qu'anciennement il a existé dans le vuide actuel du cirque une montagne de granit, et que ce cirque est le produit des débris de cette montagne. car comment ne resteroit-il aucun vestige de cette montagne? on conçoit bien que sa tête auroit pu se détruire, mais son corps, la base du moins, protégée par les débris de sa tête accumulés autour d'elle qu'est ce qui auroit pu l'anéantir; d'ailleurs les parois intérieures du cirque quoique très-escarpées ne sont pourtant pas verticale; elles s'avancent de tous côtés vers l'intérieur; et le fond, le milieu même du cirque n'est point du granit, il est de la même nature que ses bords. enfin nous avons reconnu que les montagnes qui forment la couronne du mont-rose se prolongent au dehors à de grandes distances en sorte que leur ensemble forme une masse incomparablement plus grande que celle qui auroit rempli le vuide intérieur du cirque. «il faut donc reconnoître, comme tous les phénomènes le démontrent d'ailleurs, qu'il existe de montagnes de roches feuilletées, composées des mêmes élémens que le granit, et qui sont sorties comme lui des mains de la nature sans avoir commencé par êtres elles-mêmes des granits[ ].» [footnote : m. de saussure, upon the evidence before us, might have gone farther, and maintained that the masses of granite, which here traverse the strata in form of veins and irregular blocks, had been truly of a posterior formation. but this is a subject which we shall have afterwards to consider in a particular manner; and then this example must be recollected.] here is an example the most interesting that can be imagined. those mountains are the highest in europe, and their lofty peaks are altogether inaccessible upon one side. they had all been formed of the same horizontal strata. how then have they become separated peaks? and how have the valleys been hollowed out of this immense mass of elevated country?--no otherwise than as we may perceive it, upon every mountain, and after every flood. it is not often indeed, that, in those alpine regions, any considerable tract of country is to be found, where an example so convincing is exhibited. it is more common for those mountains of primary strata or schistus to rise up in ridges, which, though divided into great pyramids, may still be perceived as connected in the direction of their erected strata. these last, although affording the most satisfactory view of that mineral operation by which land, formed and consolidated at the bottom of the sea, had been elevated and displaced, are not so proper to inform us of the amazing waste of those extremely consolidated bodies, as are those where the strata have preserved their original horizontal portion. it is in this last case, that there are data remaining for calculating the _minimum_ of the waste that must have been made of those mountains, by the regular and long continued operations of the atmospheric elements upon the surface of this earth. it is the singularity of these horizontal strata in that extensive alpine mass, which seems to have engaged m. de saussure, who has inspected so much of those instructive countries, to make a tour around those mountains, and to give us a particular description of this interesting place. now, from this description, it is evident, that there is an immense mass of primary or alpine strata nearly in the horizontal position, which is common to all the strata at their original formation; that this horizontal mass had been raised into the highest place of land upon this globe; and that, in this high situation, it has suffered the greatest degradation, in being wasted by the hand of time, or operations of the elements employed in forming soil for plants, and procuring fertility for the use of animals. here is nothing but a truth that may almost every where be perceived; but here that important truth is to be perceived on so great a scale, as to enable us to enlarge our ideas with regard to the natural operations of this earth, and to overcome those prejudices which contracted views of nature, and magnified opinions of the experience of man may have begotten,--prejudices that are apt to make us shut our eyes against the cleared light of reason. abundant more examples of this kind, were it necessary, might be given, both from this very good observator, and from m. de luc[ ]. [footnote : vid. discours sur l'histoire naturelle de la suisse, passim; _but more particularly under the article of route du grindle_ wald à meiringen _dans le pays de hasti:_ also hist: de la terre, lettre . p. , et lettre . page , etc.] i will now only mention one from this last author, which we find in the journal de physique, juin . «entre francfort et hanau, le mein est bordé sur ses deux rives, de collines dans lesquelles la _lave_ se trouve enchâssée entre des _couches calcaires_. ces _couches_ sont très-remarquables par leur contenue, qui est le même au-dessus et au-dessous de la _lave_, et qu'on retrouve dans les _couches_ d'une grande étendue de pays, ou, comme d'ordinaire, on voit leurs sections abruptes dans les flancs de collines, mais sans _lave_, excepté dans le lieu indiqué.» the particular structure of those lime-stone strata, with the body of basaltes or subterraneous lava which is interposed among them, shows evidently the former connection of those two banks of the river, by solid matter, the same as that which we see left there, and in the flanks of those hills. that which is wanting, therefore, of those stratified masses, in that great extent of country, marks out to us the minimum of what has been lost, in having been worn by the attrition of travelled materials. i would now beg leave, for a moment, to transport my reader to the other side of the atlantic, in order to perceive if the same system of rivers wearing mountains is to be found in that new world, as we have found it in the old. of all the mountains upon the earth, so far as we are informed by our maps, none seem to be so regularly disposed as are the ridges of the virginian mountains. there is in that country a rectilinear continuity of mountains, and a parallelism among the ridges, no where else to be observed, at least not in such a great degree. at neither end of those parallel ridges is there a direct conveyance for the waters to the sea. at the south end, the allegany ridge runs across the other parallel ridges, and shuts up the passage of the water in that direction. on the north, again, the parallel ridges terminate in great irregularity. the water therefore, that is collected from the parallel valley, is gathered into two great rivers, which break through those ridges, no doubt at the most convenient places, forming two great gapes in the _blue ridge_, which is the most easterly of those parallel ridges. now, so far as mountains are in the original constitution of a country, the ridges of those mountains must have been a directing cause to the rivers. but so far as rivers, in their course from the higher to the lower country, move bodies with the force of their rolling waters, and wear away the solid strata of the earth, we must consider rivers as also forming mountains, at least as forming the valleys which are co-relative in what is termed _mountain_. nothing is more evident than the operation of those two causes in this mountainous country of virginia; the original ridges of mountains, or indurated and elevated land, have directed the courses of the rivers, and the running of those rivers have modified the mountains from whence their origin is taken. i have often admired, in the map, that wonderful regularity with which those mountains are laid down, and i have much wished for a sight of that gap, through which the rivers, gathered in the long valleys of those mountains, break through the ridge and find a passage to the sea. a description of this gap we have by mr jefferson, in his notes on virginia. «the passage of the potomac, through the blue ridge, is perhaps one of the most stupendous scenes in nature. you stand on a very high point of land. on your right comes up the shenandoah, having ranged, along the foot of the mountains, an hundred miles to seek a vent. on the left approaches the potomac, in quest of a passage also. in the moment of their junction, they rush together against the mountain, rend it asunder, and pass off to the sea. «the first glance of this scene hurries our senses into the opinion, that this earth had been erected in time; that the mountains were formed first; that the rivers began to flow afterwards; that in this place particularly they have been dammed up by the blue ridge of mountains, and have formed an ocean which filled the whole valley; that, continuing to rise, they have at length broken over this spot, and have torn the mountain down from its summit to its base. the piles of rock on each hand, but particularly on the shenandoah, the evident marks of this disrupture and avulsion from their beds, by the most powerful agents of nature, corroborate the impression. but the distant finishing which nature has given to the picture is of a different character. it is a true contrast to the foreground. it is as placid and delightful as that is wild and tremendous. for the mountain being cloven asunder, she presents to your eye, through the cleft, a small catch of smooth blue horizon at an infinite distance in the plain country, inviting you, as it were, from the riot and tumult roaring around, to pass through the breach, and partake of the calm below. here the eye ultimately composes itself; and that way too the road happens actually to lead. you cross the potomac above the junction, pass along its side through the base of the mountain for three miles, its terrible precipices hanging in fragments over you, and within about twenty miles reach of frederick town, and the fine country around it. this scene is worth a voyage across the atlantic. yet here, as in the neighbourhood of the natural bridge, are people who have passed their lives within half a dozen of miles, and have never been to survey these monuments of a war between the rivers and mountains, which must have shaken the earth itself to its center.» to this description of the passage of the potomac may be added what mr jefferson, in the appendix, has given from his friend mr thomson, secretary of congress. «the reflections i was led into on viewing this passage of the potomac through the blue ridge were, that this country must have suffered some violent convulsion, and that the face of it must have been changed from what it probably was some centuries ago; that broken and ragged faces of the mountain on each side of the river; the tremendous rocks which are left with one end fixed in the precipice, and the other jutting out, and seemingly ready to fall for want of support; the bed of the river for several miles below obstructed, and filled with the loose stones carried from this mound; in short, every thing on which you cast your eye evidently demonstrates a disrupture and breach in the mountain, and that before this happened, what is now a fruitful vale, was formerly a great lake, or collection of water, which possibly might have here formed a mighty cascade, or had its vent to the ocean by the susquehanna, where the blue ridge seems to terminate. besides this, there are other parts of this country which bear evident traces of a like convulsion. from the best accounts i have been able to obtain, the place where the delaware now flows through the kittatinny mountain, which is a continuation of what is called the north ridge, or mountain, was not its original course, but that it passed through what is now called the wind-gap, a place several miles to the westward, and above an hundred feet higher than the present bed of the river. this wind-gap is about a mile broad, and the stones in it such as seem to have been washed for ages by water running over them. should this have been the case, there must have been a lake behind that mountain; and, by some uncommon swell in the waters, or by some convulsion of nature, the river must have opened its way through a different part of the mountain, and meeting there with less obstruction, carried away with it the opposing mounds of earth, and deluged the country below with the immense collection of waters to which this new passage gave vent. there are still remaining, and daily discovered, innumerable instances of such a deluge on both sides of the river, after it passed the hills above the falls of trenton, and reached the champaign. on the new jersey side, which is flatter than the pennsylvania side, all the country below croswick hills seems to have been overflowed to the distance of from ten to fifteen miles back from the river, and to have acquired a new soil, by the earth and clay brought down and mixed with the native sand. the spot on which philadelphia stands evidently appears to be made ground. the different strata through which they pass in digging for water, the acorns, leaves, and sometimes branches which are found above twenty feet below the surface, all seem to demonstrate this.» how little reason there is to ascribe to extraordinary convulsions the excavations which are made by water upon the surface of the earth, will appear most evidently from the examination of that natural bridge of which mention is made above, and which is situated in the same ridge of mountains, far to the south, upon a branch of james's river. mr jefferson gives the following account of it. "the natural bridge, the most sublime of nature's works, is on the ascent of a hill, which seems to have been cloven through its length by some great convulsion. the fissure, just at the bridge, is by some admeasurements feet deep, by others ; it is about feet wide at the bottom, and feet at the top; this of course determines the length of the bridge, and its height from the water. its breadth in the middle is about feet, but more at the ends; and the thickness of the mass at the summit of the arch about feet. a part of its thickness is constituted by a coat of earth, which gives growth to many large trees. the residue, with the hill on both sides, is one solid rock of lime-stone. the arch approaches the semi-elliptical form; but the larger axis of the ellipsis, which would be the cord of the arch, is many times longer than the transverse. though the sides of the bridge are provided in some parts with a parapet of fixed rock, yet few men have resolution to walk to them, and look over into the abyss. you involuntarily fall on your hands and feet, and creep to the parapet, and look over it. looking down from this height about a minute gave me a violent headache. if the view from the top be painful and intolerable, that from below is delightful in the extreme. it is impossible for the emotions arising from the sublime to be felt beyond what they are here. on the sight of so beautiful an arch, so elevated, so light, and springing as it were up to heaven, the rapture of the spectator is really indescribable! the fissure, continuing narrow, deep, and straight, for a considerable distance above and below the bridge, opens a short but very pleasing view of the north mountain on one side, and blue ridge on the other, at the distance each of them of about five miles. this bridge is in the county of rockbridge, to which it has given name, and affords a public and commodious passage over a valley, which cannot be crossed elsewhere for a considerable distance. the stream passing under it is called cedar creek: it is a water of james's river, and sufficient in the driest seasons to turn a grist mill, though its fountain is not more than two miles above[ ]." [footnote : upon this occasion it may be observed, the most wonderful thing, with regard to cosmology, is that such remnants, forming bridges, are so rare; this therefore must be an extraordinary piece of solid rock, or some very peculiar circumstances must have concurred to preserve this monument of the former situation of things.] thus both in what is called the old world and the new, we shall be astonished in looking into the operations of time employing water to move the solid masses from their places, and to change the face of nature, on the earth, without defacing nature. at all times there is a terraqueous globe, for the use of plants and animals; at all times there is upon the surface of the earth dry land and moving water, although the particular shape and situation of those things fluctuate, and are not permanent as are the laws of nature. it is therefore most reasonable, from what appears, to conclude, that the tops of the mountains have been in time past much degraded by the decay of rocks, or by the natural operations of the elements upon the surface of the earth; that the present mountains are parts which either from their situation had been less exposed to those injuries of what is called time, or from the solidity of their constitution have been able to resist them better; and that the present valleys, or hollows between the mountains, have been formed in wasting the rock and in washing away the soil. if this is the case, that rivers have every where run upon higher levels than those in which we find them flowing at the present, there must be every where to an observing eye marks left upon the sides of rivers, by which it may be judged if this conclusion be true. i shall now transcribe a description of a part of the _vallais_ by which this will appear. (discours sur l'histoire naturelle de la suisse.) «après avoir passé le village de saint-leonard, on commence à monter la montagne de la platière; cette route est on ne peut plus intéressante pour le naturaliste etc. «on se trouve fort élevé au-dessus du rhône quand on est sur le haut de ce chemin, dont on découvre un de plus singuliers, des plus riches, et de plus variés passages qu'on puisse imaginer. on voit sous ses pieds le rhône serpenter dans le lit qu'il se creuse actuellement, car il change et tout prouve qu'il en a souvent changé; une quantité prodigieuse de petites isles le séparent et le coupent en une multitude de canaux et de bras; ces isles sont couvertes les unes d'arbres, d'arbustes, de pâturages, de bosquets et de verdure, d'autres de pierres, de sable, et de débris de rochers; quelques-unes sont formées ou occasionnées par un amas de troncs d'arbres entassés avec de grands sapins renversés dont les long tiges hérissées de branches droites et nues représentent des chevaux de frise, et donnent l'idée de ces abatis destinés à preserver un pays contre l'approche de l'ennemi. du côté du bas vallais, on suit à perte de vue le fleuve dans ses sinuosités et ses détours, on l'apperçoit également dans le haut vallais; des avances de montagne le cachent quelquefois: il reparoît et diminue insensiblement en approchant de ces monts élevés ou il prend sa source: le fond du vallon paroît être de niveau, s'abaisser seulement d'une pente douce du côté du bas vallais: des mamelons, des hauteurs des monticules isolés, quelquefois groupés de différentes manieres, sont répandus dans cet espace, et rappellent la vue d'une pré dévasté par les taupes; plusieurs de ces hauteurs sont surmontées des ruines d'antiques châteaux, d'eglises, et de chapelles; des villages distribués ça et là enrichissent ce fond, qui d'ailleurs est couvert de pâturages, de champs d'arbres, de bois, et de bosquets; les enclos des possessions le coupent en mille figure bizarres et irrégulières. ces monticules avec leurs fabriques s'élèvent au-dessus de tous ces objets variés; quelques-unes se distinguent par leur côtés écroulés qui sont à pic; la blancheur de ces éboulemens contraste singulièrement avec les verts qui sont les couleurs dominantes du vallon. au-de-la des coteaux, des montagnes s'élèvent et vont s'appuyer et s'adosser à ces masses, à ces colosses énormes de rochers à pic élevés comme des murailles et d'une hauteur prodigieuse qui forment cette barrière qui sépare le vallais de la savoie. les contours du pied de ces monts forment des entrées de vallons et de vallées d'ou descendent et se précipitent des torrens qui viennent grossir les eaux du rhône; la vue cherche à pénétrer et à s'étendre dans ces espaces, l'imagination cherche vainement des passages dans effrayantes limites, parmi ces écueils et ces rochers amoncelés, elle est arrêtée partout; de noires forêts de sapin sont suspendues parmi ces rochers blancs-jaunâtres, qui se terminent enfin par une multitude d'aiguilles et de pyramides qu'on voit percer au travers des neiges et des glaces, s'élancer dans les nues, s'y cacher et s'y perdre. «en examinant de plus près ces mamelons répandus dans le vallon, on voit qu'ils sont composés de pierres, de sables, et de débris rapportés et amoncelés sans ordre depuis des temps dont rien ne peut fixer l'époque: on voit que les eaux du rhône ont coulé à leurs pied, qu'il en a miné plusieurs et a occasionné leurs chutes et leurs ruines. on voit actuellement quelques mamelons qui subissent ces mêmes dégradations, et fournissent au rhône les matériaux dont il va former plus loin ces atterissemens dont nous avons parlé. la confusion et le désordre qui se remarque dans la composition intérieure de ces mamelons prouvent qu'ils ne sont pas le produit de la mer ou des eaux qui ont travaillé successivement et lentement à la formation de la plupart des terrains; mais que le fond de ce vallon a été rempli des décombres et des débris des montagnes supérieures, qu'ils y ont été entraînés par des inondations et des débordemens subits; que les eaux du rhône ensuite ont parcouru ce vallon qu'il a souvent changé de lit; que c'est en tournant et en circulant dans ce terrain nouvellement formé, qu'il a creusé les espaces qui sont entre ces mamelons, et que c'est en creusant le terrain qu'ils se sont élevés; leurs formes et leurs pentes allongées vers le bas vallais, sont de nouvelles preuves que ce sont les eaux actuelles qui ont changé la surface de ce terrain, nous verrons de nouvelles preuves de ce que nous disons en avançant d'avantage vers le haut vallais; il n'y a peut-être point d'endroit plus propre à étudier le travail des eaux que ce vallon qu'on a la facilité de voir et d'examiner sous des aspects différentes.» another example of the same kind, with regard to the bed of the rhine, we have from the same author. (discours, etc. page .) «_de richenau à coire, troyen, et saint-gal._ «pour aller à coire on passe le port qui est sur le haut rhin; en côtoyant ce fleuve, qui coule dans un fond, on entre dans une plaine de niveau, qui n'a qu'une pente très insensible de trois quarts de lieue; le fond du terrain n'est qu'un amas de pierres roulées de toutes espèces. les deux côtés sont bordés de montagnes calcaire qui courent parallèlement entr'elles. celle de la gauche, au pied de laquelle coule le rhine, est très rapide et perpendiculaire à son sommet; celle qui est à droite de la plaine ou petit vallon, puisqu'il se trouve entre des montagnes, est moins haute, plus boisée, et couverte de sapins. le vallon est aussi couvert, en partie, de très-grands et beaux pins; mais ce qu'on y voit de plus remarquable, c'est une douzaine de gros mamelons ou butes, élevées de cinquante à soixante toises, plus ou moins isolée, et à différentes distances les unes des autres; ces butes sont rondes, la plupart allongées dans le sens du vallon, et composées de débris calcaires et de sables; le fond du vallon est mêlé de plus d'espèces de galets. on ne croit pas se tromper en disant que ce vallon a été rempli de matières apportées par les eaux jusqu'à la hauteur ou sont encore actuellement les mamelons; que de nouvelles inondations ont ensuite creusé et entraîné ce qui manque de terrain à ces mamelons; que c'est en circulant autour de ces mamelons que les eaux leur ont donné la forme ronde; et surtout allongée dans le sens du vallon, et que c'est par le moyen de ces mêmes eaux que le fond actuel de cette plaine a pris ce niveau et cette pente insensible vers un pays plus ouvert qui est au-dela. on a déjà fait mention de pareils mamelons qui se trouvent dans le vallon du vallais parcouru par le rhône.» these examples may also be supported by what this author observes in another place[ ]. [footnote : discours, etc. page .] «le vallon où est situé meiringen, est visiblement formé par le dépôt des eaux, il est de niveau, et s'étend trois lieues en longueur jusqu'au lac de brientz, à la suite duquel est le même terrain nivelé, qui va jusqu'au lac de thun, dont on a parlé. une autre observation qui concourt à favoriser ce sentiment, c'est que toutes les roches calcaires, qui entourent le vallon, sont à pic, qu'on y remarque des cavités circulaires et des enfoncemens à même hauteur et à différents points, qui constatent la fouille et le mouvement des eaux contre ces parois.» thus we have seen the operation of the atmospheric elements degrading mountains, and hollowing out the valleys of this earth. the land which comes from the mineral region in a consolidated state, in order to endure the injuries of those atmospheric elements, must be resolved in time for the purposes of fertilising the surface of this earth. in no station whatever is it to be exempted from the wasting operations, which are equally necessary, in the system of this world, as were those by which it had been produced. but with what wisdom is that destroying power disposed! the summit of the mountain is degraded, and the materials of this part, which in a manner has become useless from its excessive height, are employed in order to extend the limits of the shore, and thus increase the useful basis of our dwellings. it is our business to trace this operation through all the intermediate steps of that progress, and thus to understand what we see upon the surface of this earth, by knowing the principles upon which the system of this world proceeds. chap. xi. _facts and opinions concerning the natural construction of mountains and valleys._ the valley of the rhône is continued up to the mountain of st. gothard, which may be considered as the centre of the continent, since, from the different sides of this mountain, the water runs in all directions. to the german sea it runs by the rhine, to the mediterranean by the rhone, and to the adriatic by the po. here it may be proper to take a general view of this mountainous country, or that great mass of rock or solid strata which has been either formed originally in its present shape, or has been excavated by the constant operation of water running from the summit in all the different directions. on the one hand, it is supposed that the forming cause which had produced those mountains, in collecting their materials at the bottom of the sea, had also determined the shape in which their various ridges are at present found; on the other hand, it is supposed that the destructive causes, which operate in degrading mountains, have immediately contributed to produce their present forms, and that it is only mediately or more remotely that this shape has been determined by mineral operations and the constitution of the solid parts, which thus oppose the wearing operations of the surface with different degrees of hardness and solidity. whether natural appearances correspond with the one or the other of those two different suppositions, every person who has the opportunity of making such an examination, and has sufficient knowledge of the subject to judge from his observation, will determine for himself. i will here give the opinion of a person who has had great opportunities for this purpose, who is an intelligent as well as an attentive observator, and who has had particularly this question in his view. it is from 'tableaux de la suisse'[ ]. [footnote : «discours sur l'histoire naturelle de la suisse.»] «quand nous nous sommes trouvé sur ces points élevés, nous avons toujours considéré le total des montagnes prises ensemble, leurs situations respectives, les unes par rapport aux autres; afin de reconnoître, s'il y avoit quelque chose de constant dans leurs position; rien n'est plus varié. dans la grande chaîne de montagnes qui sépare le canton de berne du vallais d'un côté, et les alpes qui séparent le vallais de la savoie de l'autre, en considérant le course du rhône sous differens points de vue, on n'a point vu que les angles saillans de ces très hautes montagnes fussent opposés aux angles rentrans des montagnes qui sont vis-à-vis; le fameux vallon qui est sur le haut du saint-gothard, le point le plus élevé de l'europe, contredit également cette observation, aussi que les positions de la plus grande partie des montagnes qui forment son vaste circuit. le vallon de scholenen, qui a plus de huit lieues, et dans lequel la reusse coule du sommet du saint-gothard jusqu'au lac de lucerne, offre à peine quelques exemples d'angles rentrans opposés à des angles saillans. les nombreux vallons que nous avons constamment traversés ceux qui conduisent au grindelwald, et celui qui mène au pays de hasli qui sont sous nos yeux, n'établirent pas d'avantage cette correspondance d'angles saillans et angles rentrans, qu'on regarde comme si constante. dans les montagnes basses, du troisième et quatrième ordre, ou inférieures, on remarque plus souvent cette correspondance, encore n'est-elle pas constante: les eaux ordinaires ont formé ces vallons; mais si on veut donner une théorie générale, c'est assurement dans les plus hautes montagnes qu'il faut prendre ses exemples. ce qui se trouve au-dessous de ces points les plus élevés, a pris sa forme de la disposition même des plus hauts sommets.» m. de saussure, in his second volume of _voyages dans les alpes_, gives the strongest confirmation to the theory of the gradual degradation of mountains by the means of rain. «§ . je reviens aux observations. il en est une très importante pour la théorie de la terre, dont on peut du haut du cramont apprécier la valeur, mieux que d'aucun autre site; je veux parler de la fameuse observation de _bourguet_ sur la correspondance des angles saillans avec les angles rentrans des vallées. j'ai a déjà dit un mot dans le er. volume, § , mais j'ai renvoyé à ce chapitre les developpemens que je vais donner. «ce qui avoit fait regarder cette observation comme très-importante, c'est que l'on avoit cru qu'elle pourroit servir à démontrer que les vallées ont été creusées par des courans de la mer, dans le temps où elle couvroit encore les montagnes; ou que les montagnes qui bordent ces vallées avoient été elles-mêmes formées par l'accumulation des dépôts rejetés sur les bords de ces mêmes courans. «mais l'inspection des vallées que l'on découvre du haut du cramont démontre pleinement le peu de solidité de ces deux suppositions. en effet, toutes les vallées que l'on découvre du haut de cette cime sont fermées, au moins à l'une de leurs extrémités et quelques-unes à leurs deux extrémités, par des cols élevés, ou même par des montagnes d'une très-grande hauteur: toutes sont coupées à angles droits par d'autres vallées, et l'on voit enfin clairement que la plupart d'entr'elles ont été creusées, non point dans la mer, mais, ou au moment de sa retraite, ou depuis sa retraite, par les eaux des neiges et des pluies. «on a d'abord sous ses yeux la grande vallée de l'allée-blanche, qui étant parallèle à la direction général de cette partie des alpes, est du nombre de celles que je nomme _longitudinales_; et l'on voit cette vallée barrée à l'une de ses extrémités par le col de la seigne et à l'autre par le col ferret. en se retournant du côté de l'italie, on voit plusieurs vallées à-peu-près parallèles à celle-là, comme celle de la tuile, celle du grand saint bernard, qui toutes aboutissent, par le haut, à quelque col très-élevé, et par le bas, à la doire, où elles viennent se jeter vis-à-vis de quelque montagne qui leur correspond de l'autre côté de cette vallée. «si l'on considère ensuite cette même vallée de la doire, qui descend de courmayeur à yvrée, on la verra barrée par le mont-blanc et par la chaîne centrale, qui la coupent à angles droits dans la partie supérieure. on verra cette même vallée s'ouvrir, dans un espace de sept ou huit lieues, deux ou trois inflexions tout-à-fait brusques; et on la verra enfin coupée à angles droits par une quantité de vallées qui viennent y verser leurs eaux, et qui sont elles mêmes coupées par d'autres, dont elles reçoivent aussi le tribut. or quand on réfléchit à la largeur et à l'étendue des courans de la mer, peut-on concevoir que ces sillons étroits, barrés, qui se coupent en échiquier à de très-petites distances, aient pu être creusés par de semblables courans. «l'observation de la correspondance des angles, fut-elle aussi universelle qu'elle l'est peu, ne prouveroit donc autre chose, sinon que les vallées sont nées de la fissure et de l'écartement des montagnes, ou qu'elles ont été creusées par les torrens et les rivières qui y coulent actuellement. on voit un grand nombre de vallées naître, comme je l'ai fait voir au bon-homme, § , sur les flancs d'une montagne; on les voit s'élargir et s'approfondir a proportion des eaux qui y coulent; un ruisseau qui sort d'une glacier, ou qui sort d'une prairie, creuse un sillon, petit d'abord, mais qui s'agrandit successivement à mesure que ses eaux grossissent, par la réunion d'autres sources ou d'autres torrens. «il n'est même pas nécessaire, pour se convaincre de la vérité da ces faits, de gravir sur le cramont. il suffit de jeter les yeux sur la premiere carte que l'on trouvera sous la main, des pyrénées, de l'apennin, des alpes, ou de quelqu'autre chaîne de montagnes que ce puisse être. on y verra toutes les vallées indiquées par le cours des rivieres; on verra ces rivieres et les vallées dans lesquelles elles coulent, aboutir par une de leurs extrémités au sommet de quelque montagne ou de quelque col élevé. les replis tortueux d'un grand fleuve, indiqueront une vallée principale, dans laquelle des torrens ou des rivieres qui indiquent d'autres vallées moins considérables, viennent aboutir, sous des angles plus ou moins approchans de l'angle droit. or ces rivieres qui viennent de droite et de gauche se jeter dans la vallée principale, ne s'accordent pas pour se jeter par paires dans le même point du fleuve; elles sont comme les branches d'un arbre qui s'implantent alternativement sur son tronc, et par conséquent, chaque petite vallée se jette dans la vallée principale vis-à-vis d'une montagne. et de plus on verra aussi sur les cartes que même les plus grandes vallées ont presque toutes des étranglemens qui forment des écluses, des fourches, des défilés. «je ne prétends cependant pas que l'érosion des eaux pluviales, des torrens et des rivieres, soit l'unique cause de la formation des vallées: le redressement des couches des montagnes nous force à en admettre une autre, dont je parlerai ailleurs; j'ai voulu seulement prouver, ici que la correspondance des angles, lorsqu'elle a lieu dans les vallées, ne prouve point que ces vallées soient l'ouvrage des courans de la mer.» the place to which m. de saussure here remits us is where he afterwards, in describing the _val d'aoste_, makes the following observation. «(§ .) au-dela de nuz, les montagnes qui bordent au midi la vallée, et dont on voit d'ici très-bien la structure, sont composées de grandes couches appliquées les unes contre les autres, et terminées par des cimes aigues, escarpées contre le midi, elles tournent ainsi le dos à la vallée, dont la direction est toujours à degrés de l'est par nord. celles de la gauche que nous côtoyons, et qui sont de nature schisteuse, tournent aussi le dos à la vallée en s'élevant contre le nord. je crois pouvoir conclure de là, que cette vallée est une de celles dont la formation tient à celle des montagnes mêmes, et non point à l'érosion des courans de la mer ou des rivières. les vallées de ce genre, paroissent avoir été formées par un affaissement partiel des couches des montagnes, qui ont consenti, dans la direction qu'ont actuellement ces vallées.» here i would beg leave to differ a little from this opinion of m. de saussure, at least from the manner in which it is expressed; for perhaps at bottom our opinions upon this subject do not differ much. m. de saussure says that the formation of this valley depends upon the mountains themselves, and not upon the erosion of the rivers. i agree with our author, so far as the mountains may have here determined the shape and situation of the valley; but, so far as this valley was hollowed out of the solid mass of our earth, there cannot be the least doubt that the proper agent was the running water of the rivers. the question, therefore, comes to this, how far it is reasonable to conclude that this valley had been hollowed out of the solid mass. now, according to the present theory, where the strata consolidated at the bottom of the sea are supposed to be erected into the place of land, we cannot suppose any valley formed by another agent than the running water upon the surface, although the parts which are first to be washed away, and those which are to remain longest, must be determined by a concurrence of various circumstances, among which this converging declivity of the strata in the bordering mountains, doubtless, must be enumerated. with regard to any other theory which shall better explain the present shape of the surface of the earth, by giving a cause for the changed position of the strata originally horizontal, i cannot form a judgment, as i do not understand by what means strata, which were formed horizontally, should have been afterwards inclined, unless it be that of a power acting under those strata, and first erecting them in relation to the solid globe on which they rested. besides, in supposing this valley original, and not formed by the erosion of the rivers, what effect should we ascribe to the transport of all those materials of the alps, which it is demonstrable must have travelled through this valley? whether is it more reasonable to suppose, on the one hand, that the action and attrition of all the hard materials, running for millions of ages between those two mountains, had hollowed out that mass which originally intervened; or, on the other, that this valley had been originally formed in its present shape, while thousands of other valleys have been hollowed out of the solid mass? but to put this question out of doubt, with regard to this very valley of the river _doire_, m de saussure has given us the following decisive fact, § : «immédiatement au-dessus de cette source, est un rocher qui répond si précisément à un autre rocher de la même nature, situé de l'autre côté de la vallée de courmayeur, qu'on ne sauroit douter qu'ils n'aient été anciennement unis par une montagne intermédiaire, détruite par les ravages du temps.» now, to see how little the situation of the strata influences the shape of the valleys, i shall transcribe the two paragraphs immediately following that which has given occasion to the present discussion. «un peu au-dela de nux, la vallée cesse d'être large et plane, comme elle étoit dans le environs de la cité; elle devient étroite et très variée; là stérile et sauvage, ici couverte de vergers et de prairies arrosées par la doire. «§ . les couches des montagnes à notre gauche, qui depuis la cité avoient constamment couru à l'est et monté au nord, paroissent changer à un quart de lieue du village de chambaise, qui est à une lieue et un quart de nux. elles montent d'abord au sud-est, et peu plus loin droit au sud, tandis que l'autre côté de la vallée elles paroissent monter à l'est.» in every mountain, and in every valley, the solid parts below have contributed in some manner to determine the shape of the surface of the earth; but in no place is the original shape of the earth, such as it had first appeared above the sea, to be found. every part of the land is wasted; even the tops of the mountains, over which no floods of water run, are degraded. but this wasting operation, which affects the solid rock upon the summit of the mountain, operates slowly in some places, compared with that which may be observed in others. now, it is in the valleys that this operation is so perceptible; and it is in the valley that there is such a quick succession of things as must strike the mind of any diligent observer; but this is the reason why we must conclude, that at least all the valleys are the operation of running water in the course of time. if this is granted, we have but to consider the mountains as formed by the hollowing out of the valleys, and the valleys as hollowed out by the attrition of hard materials coming from the mountains. here is the explanation of the general appearance of mountain and valley, of hill and dale, of height and hollow; while each particular shape must have its dependence, consequently its explanation, upon some local circumstance. but, besides the general conformation of mountains and valleys, there may be also, in the forms of mountains, certain characters depending upon the species of substances or rocks of which they are composed, and the general manner in which those masses are wasted by the operations of the surface. thus there is some character in the external appearance of a hill, a mountain, or a ridge of hills and mountains; but this appearance is generally attended with various circumstances, or is so complicated in its nature, as to be always difficult to read; and it is but seldom that it affords any very particular information; although, after knowing all the state and circumstances of the case, i have always found the appearances most intelligible, and strictly corresponding with the general principle of atmospheric influence acting upon the particular structure of the earth below. m. de saussure has given us an observation of this kind, in describing the mountains through which the rhône has made its way out of the alps, at the bottom of the vallée. «§. . plus loin le village de _juviana_ ou envionne on voit des rochers qui ont une forme que je nomme _moutonnée_; car on est tenté de donner des noms à des modifications qui n'en ont pas, et qui ont pourtant un caractère propre. les montagnes que je désigne par cette expression sont composées d'un assemblage de têtes arrondies, couvertes quelquefois de bois, mais plus souvent d'herbes, ou tout au plus de brousailles. ces rondeurs contiguës et répétées forment en grand l'effet d'une toison bien fournie, ou de ces perruques que l'on nommé aussi _moutonnées_. les montagnes qui se présentent sous cette forme, sont presque toujours de rochers primitives, ou au moins des stéatites; car je n'ai jamais vu aucune montagne de pierre à chaux ou d'ardoise revêtir cette apparence. les signes qui peuvent donner quelque indice de la nature des montagnes, à de grandes distances et au travers des plantes qui le couvrent, sont en petit nombre, et méritent d'être étudiés et consacrés par des termes propres.» when philosophers propose vague theories of the earth, theories which contain no principle for investigating either the general disorder of strata or the particular form of mountains, such theories can receive no confirmation from the examination of the earth, nor can they afford any rule by which the phenomena in question might be explained. this is not the case when a theory presents both the efficient and final cause of those disorders in bodies which had been originally formed regular, and which shows the use as well as means for the formation of our mountains. here illustration and confirmation of the theory may be found in the examination of nature; and natural appearances may receive that explanation which the generalization of a proper theory affords. the particular forms of mountains depend upon the compound operation of two very different causes. one of these consists in those mineral operations by which the strata of the earth are consolidated and displaced, or disordered in the production of land above the sea; the other again consists in those meteorological operations by which this earth is rendered a habitable world. in the one operation, loose materials are united, for the purpose of resisting the dissolving powers which act upon the surface of the earth; in the other, consolidated masses are again dissolved, for the purpose of serving vegetation and entertaining animal life. but, in fulfilling those purposes of a habitable earth, or serving that great end, the land above the level of the sea is wasted, and the materials are transported to the bottom of the ocean from whence that consolidated land had come. at present we only want to see the cause of those particular shapes which are found among the most elevated places of our earth, those places upon which the wasting powers of the surface act with greatest energy or force. in explaining those appearances of degraded mountains variously shaped, the fact we are now to reason upon is this; first, that in the consolidated earth we find great inequality in the resisting powers of the various consolidated bodies, both from the different degrees of consolidation which had taken place among them, and the different degrees of solubility which is found in the consolidated substances; and, secondly, that we find great diversity in the size, form, and positions of those most durable bodies which, by resisting longer the effects of the wearing operations of the surface, must determine the shape of the remaining mass. now so far as every particular shape upon the surface of this earth is found to correspond to the effect of those two causes, the theory which gave those principles must be confirmed in the examination of the earth; and so far as the theory is admitted to be just, we have principles for the explanation of every appearance of that kind, whether from the forming or destroying operations of this earth, there being no part upon the surface of this earth in which the effect of both those causes must not more or less appear. but though the effects of those two causes be evident in the conformation of every mountainous region, it is not always easy to analyse those effects so as to see the efficient cause. without sections of mountains their internal structure cannot be perceived, if the surface which we see be covered with soil as is generally the case. it is true, indeed, that the solid bodies often partially appear through that covering of soil, and so far discover to us what is to be found within; but as those solid parts are often in disorder, we cannot, from a small portion, always judge of the generality. besides, the solid parts of mountains is often a compound thing, composed both of stratified and injected bodies; it is therefore most precarious, from a portion which is seen, to form a judgment of a whole mass which is unexplored. nevertheless, knowing the principles observed by nature both in the construction and degradation of mountains, and cautiously inferring nothing farther than the data will admit of, some conclusion may be formed, in reasoning from what is known to what is still unknown. it is with this view that we are now to consider the general forms of mountains, such as they appear to us at a certain distance, when we have not the opportunity of examining them in a more perfect manner. for, though we may not thus learn always to understand that which is thus examined, we shall learn, what is still more interesting, viz. that those mountains have been formed in the natural operations of the earth, and according to physical rules that may be investigated. we are to distinguish mountains as being either on the one hand soft and smooth, or on the other hand as hard and rocky. if we can understand those two great divisions by themselves, we shall find it easy to explain the more complex cases, where these two general appearances partially prevail. let us therefore examine this general division which we have made with regard to the external character of mountains. the soft and smooth mountains are generally formed of the schisti, when there is any considerable extent of such alpine or mountainous region. the substance is sufficiently durable to form a mountain, or sufficiently strong, in its natural state, to resist the greatest torrent of water; at the same time this fissible substance generally decays so completely, when exposed to the atmosphere, as to leave no salient rock exposed by which to characterise the mountain. of this kind are the schisti of wales, of cumberland, of the isle of man, and of the south of scotland. i do not say absolutely, that there is no other kind of material, besides the schisti which gives this species of mountain, but only that this is generally the case in alpine situations. it may be also formed of any other substance which has solidity enough to remain in the form of mountains, and at same time not enough to form salient rocks. such, for example, is the chalk hills of the isle of wight and south of england. but these are generally hills of an inferior height compared with our alpine schisti, and hardly deserve the term of mountain. this material of our smooth green mountains may be termed an argillaceous schistus; it has generally calcareous veins, and is often fibrous in its structure resembling wood, instead of being slatey, which it is in general. there is however another species of schistus, forming also the same sort of mountain; it is the micaceous quartzy schistus of the north of scotland. now it must be evident that the character of those mountains arises from there being no part of those schisti that resists the influence of the atmosphere, in exfoliating and breaking into soil; and this soil is doubtless of different qualities, according to the nature of those schisti from which the soil is formed. such mountains are necessarily composed of rounded masses, and not formed of angular shapes. they are covered with soil, which is more or less either stoney or tender, sterile or fertile, according to the materials which produce that soil. the fertile mountains are green and covered with grass; the sterile mountains again are black, or covered with heath in our climates. thus we have a general character of smooth and rounded mountains; and also a distinction in that general character from the produce of the soil indicating the nature of the solid materials, as containing, either on the one hand calcareous and argillaceous substances, or, on the other, as only containing those that are micaceous and siliceous. with regard again to the other species of mountain, which we have termed rocky, we must make a subdistinction of those which are regular, and those in which there is no regularity to be perceived. it must be plain that it is only of those which have regularity that we can form a theory. it is this, that the regularity in the shape of those mountains arises from the rock of the mountain being either on the one hand an uniform solid mass, or on the other hand a stratified mass, or one formed upon some regular principle distinguishable in the shape. in the first of these, we have a conical or pyramidal shape, arising from the gradual decay of the rock exposed to the destructive causes of the surface, as already explained in this chapter. in the second, again, we find the original structure of the mass influencing the present shape in conjunction with the destructive causes, by which a certain regularity may be observed. now, this original shape is no other than that of beds or strata of solid resisting rock, which may be regularly disposed in a mountain, either horizontally, vertically, or in an inclined position; and those solid beds may then affect the shape of the mountain in some regular or distinguishable manner, besides the other parts of its shape which it acquires upon the principle of decay. in distinguishing, at a distance, those regular causes in the form of mountains, we may not be able to tell, with certainty, what the substance is of which the mountain is composed; yet, with regard to the internal structure of that part of the earth, a person of knowledge and experience in the subject may form a judgment in which, for coming at truth, there is more than accident; there is even often more than probable conjecture. thus, a horizontal bed of rock forms a table mountain, or such as m. bouguer found in the valley of the madelena. an inclined rock of this kind forms a mountain sloping on the one side, and having a precipice upon the upper part of the other side, with a slope of fallen earth at the bottom; such as the ridges observed by m. de saussure from the top of the cramont, having precipices upon one side, which also had a respect to certain central points, an observation which draws to more than the simple structure of the mountain. were it vertical, again, it would form a rocky ridge extended in length, and having its sides equally sloped, so far as the other circumstances of the place would permit. therefore, whether we suppose the mountains formed of a rock in mass, or in that of regular beds, this must have an influence in the form of this decaying surface of the earth, and may be distinguished in the shape of mountains. it is but rarely that we find mountains formed altogether of rock, although we often find them of the other sort, where little or nothing of rock is to be seen. but often also we find the two cases variously compounded. this is the source of the difficulty which occurs in the reading of the external characters of mountains; and this is one of the causes of irregularity in the form of mountains, by which there is always some degree of uncertainty in our judgment from external appearances. we may form another distinction with regard to the structure of mountains, a distinction which depends upon a particular cause, and which will afford an explanation of some other appearance in the surface of the earth. mountains in general may be considered as, being either on the one hand associated, or on the other insulated; and this forms a distinction which may be explained in the theory, and afford some ground for judging of the internal structure from the external appearance. the associated mountains are formed by the wearing down of the most decayable, or softer places, by the collected waters of the surface; consequently there is a certain similarity, or analogy, of the mountains formed of the same materials, and thus associated. the highest of those mountains should be near the center of the mass; but, in extensive masses of this kind, there may also be more than one center. nor are all the associated mountains to be of one kind, however, to a certain extent, similarity may be expected to prevail among them. it must now be evident, that when we find mountains composed of very different materials, such as, _e.g._ of granite, and of lime-stone or marl, and when the shape of those mountains are similar, or formed upon the same principle, such as, _e.g._ the pyramidal mountains of the alps, we are then to conclude, as has already been exemplified (chap. . page .) that those consolidated masses of this earth had been formed into the pyramidal mountains in the same manner. we have there also shown that this principle of formation is no other than the gradual decay of the solid mass by gravity and the atmospheric influences. consequently, those pyramidal mountains, though composed of such different materials, may, at a certain distance, where smaller characteristic distinctions may not be perceivable, appear to be of the same kind; and this indeed they truly are, so far as having their general shape formed upon the same principle. we come now to treat of insulated mountains. here volcanos must be mentioned as a cause. by means of a volcano, a mountain may be raised in a plain, and a volcanic mountain might even rise out of the sea. the formation of this species of mountain requires not the wearing operations of the earth which we have been considering as the modifier of our alpine regions. this volcanic mountain has a conical shape, perhaps more from the manner of its formation which is accretion, than from the wasting of the surface of the earth. it is not, however, of this particular specie of mountain that i mean to treat, having had no opportunity of examining any of that species. the genus of mountain which we are now considering, is that of the eruptive kind. but there is much of this eruptive matter in the bowels of the earth, which, so far as we know, never has produced a volcano. it is to this species of eruption that i am now to attribute the formation of many insulated mountains, which rise in what may be termed low countries, in opposition to the highlands or alpine situations. such is wrekin in shropshire, which some people have supposed to have been a volcano. such are the hundred little mountains in the lowlands of this country of scotland, where those insulated hills are often called by the general term _law_; as, for example, north berwick law. when masses of fluid matter are erupted in the mineral regions among strata which are to form our land; and when those elevated strata are, in the course of time, wasted and washed away, the solid mass of those erupted substances, being more durable than the surrounding strata, stand up as eminences in our land. now these often, almost always, form the small insulated mountains which are found so frequently breaking out in the lowlands of scotland. they appear in various shapes as well as sizes; and they hold their particular form from the joint operation of two different causes; one is the extent and casual shape of the erupted mass; the other is the degradation of that mass, which is wasted by the influences of the atmosphere, though wasted slower than the strata with which it was involved. when the formation of this erupted mass has been determined by the place in any regular form, which may be distinguished in the shape of a mountain, it gives a certain character which is often not difficult to read. thus, our whin-stone, interjected in flat beds between the regular strata, often presents its edge upon, or near the summit of our insolated mountains and eminences. they are commonly in the form of inclined planes; and, to a person a little conversant in this subject, they are extremely distinguishable in the external form of the hill. we have a good example of this in the little mountain of arthur's seat, by this town of edinburgh. this is a peaked hill of an irregular erupted mass; but on the south and north sides of this central mass, the basaltic matters had been forced also in those inclined beds among the regular strata. on the north side we find remarkable masses of whin-stone in that regular form among the strata, and lying parallel with them. the most conspicuous of these basaltic beds forms the summit of the hill which is called salisbury craig. here the bed of whin-stone, more than or feet thick, rises to the west at an angle of about degrees; it forms the precipicious summit which looks to the west; and this is an appearance which is distinguishable upon a hundred other occasions in the hills and mountains of this country. rivers make sections of mountains through which they pass. therefore, nothing is more interesting for bringing to our knowledge the former state of things upon the surface of this earth, than the examination of those valleys which the rivers have formed by wearing down the solid parts of alpine countries. we have already seen that the wide extensive valley of the rhône, between loiche and kolebesche, as well as the whole extensive circus of the rosa mountains, has on each side mountains of the same substances, the strata of which are horizontal; consequently, here the valley must have been hollowed out of the solid rock; for there is no natural operation by which those opposite mountains of horizontal strata could have been formed, except in the continuation of those beds. we are therefore to conclude, that the solid strata between those ridges of lofty mountains had been continuous. the most perfect confirmation which this theory could receive, would be to find that those ridges of mountains, which the rhône divides in issuing from the alps into the plain, had been also united, in forming one continued mass of solid rocks. but the observations of m. de saussure, who has most carefully examined this subject, will leave no room to doubt of that fact. this view of the entry to the valley of the rhône is too interesting not to give it here a place. it follows immediately after that which we have last transcribed. «ces montagnes que j'allai sonder au haut des prairies qui les séparent de la grande route, sont composées d'un mélange très ressemblant au précédent, et ce sont-là, les derniers rochers primitifs que l'on rencontre en sortant des alpes par cette vallée. le village de juviana, dont ils occupent les derrières, est encore à une lieue de st maurice. «§ . a l'extrémité de ces rochers, on voit une grande ravine, ou plutôt une vallée ouverte du nord au midi, dans laquelle coule le torrent de st. barthelemi. cette vallée termine les montagnes primitives que je viens de décrire: au-delà commencent les montagnes calcaires. cependant le pied de la montagne primitive, coupé par le torrent, est demeuré engagé sous les premières couches de la montagne calcaire. «au travers de cette vallée, on voit de hautes montagnes couverte de neige, situées derriere celles qui bordent notre route. la plus haute et la plus remarquable de ces montagnes se nomme la _dent_ ou _l'aiguille du midi_. de l'autre côté du rhône, on voit une autre cime aussi très-élevée, qui se nomme la _dent_ ou _l'aiguille de la morele_. ces deux hautes cimes ont entr'elles une correspondance de hauteur, de forme, et même de matière tout-à-fait singulière. l'une et l'autre présentent leurs escarpemens à la vallée du rhône. leurs cimes crénelées sont de la même couleur brune. sous ces cimes brunes, on voit de part et d'autre une bande grise, qui paroît horizontale, et au-dessous de cette bande grise, le rocher, dans l'une comme dans l'autre, reprend sa couleur jaunâtre. ces montagnes sont sûrement secondaires, les bandes grises paroissent être de pierre à chaux, et les jaunes de schiste argilleux et de grès, à en juger du moins à cette distance, car je ne les ai point observées de plus près. elles paroissent aussi appartenir à des chaînes secondaires qui passent derrière les chaînes primitives, que nous avons observées sur les bords du rhône, et quoique les bandes jaunes et grises que l'on y observe, semblent horizontales, je ne doute point que les couches mêmes, dont ces bandes sont les sections, ne descendent en arriere avec assez de rapidité; le escarpemens de ces montagnes en font une preuve à-peu-près certaine. «ces hautes montagnes auroient-elles été anciennement liées entr'elles par des intermédiaires de la même nature, que couvroient, et les primitives que nous avons observées, et toute cette vallée dans laquelle coule aujourd'hui le rhône? je me garderois bien de l'affirmer, mais je ferois tenté de le croire. «§ . depuis la vallée dont je viens de parler, et qui termine au couchant les montagnes primitives, celles qui suivent jusques à st. maurice, sont de nature calcaire à couches épaisses et suivies. ces couches s'élèvent contre les primitives que nous avons côtoyées; et celles qui en sont les plus voisines paroissent fort tourmentées; ici fléchies, là rompues. après une interruption, ces rochers sont suivis d'autres rochers, aussi calcaires, coupés à pic du côté de la vallée, et composés de grandes assises horizontales. ces rochers forment une enceinte demi-circulaire, qui vient presque se joindre à ceux qui bordent la rive droite du rhône, et former ainsi l'entrée de cette vallée, dont le fleuve ne sort que par une issue très-étroite. «la ville de st. maurice est ainsi renfermée par cette enceinte de rochers, dont les bancs épais, bien suivis, séparés par des cordons de verdure, et couronnés par des forêts, avec un hermitage niché entre ces bancs, présente une aspect singulier et pittoresque. «§ . les rochers correspondans de l'autre côté du rhône, ou sur la rive droite de ce fleuve sont aussi calcaires. la montagne qui domine cette rive, un peu au-dessus de st. maurice, est composée de couches contournées, froissées et repliées de la maniere la plus étrange. ce qu'il y a encore de remarquable, c'est que ces couches ainsi repliées en ont d'autres à côté d'elles qui sont planes, presque verticales, et d'autres sous elles, qui sont horizontales. il faudroit avoir observé de près ce singulier rocher, et avoir déterminé comment et jusqu'à quel point ces couches sont unies entr'elles pour former les conjectures sur leur origine. car la vallée est trop large pour que l'on puisse en juger avec précision d'une rive à l'autre. «on voit avec peine que cette large vallée soit aussi peu cultivée; elle est presque partout couverte, ou de marais, ou de débris des montagnes voisines. «§ . avant de quitter cette vallée, je jetterai un coup-d'oeil général sur la singulière suite de rochers qui composent la chaîne que nous venons d'observer. «les deux extrémités sont calcaires, avec cette différence, que celle qui est la plus près de martigny est mêlée de mica, tandis que celle de st maurice n'en contient point. entre ces calcaires sont refermées des rochers que l'on regarde comme primitives; et au milieu de ces roches on trouve des ardoises et des poudingues. on fait que ce dernier genre est ordinairement classé parmi les montagnes tertiaires, ou de la formation la plus récente. mais ces poudingues-ci, qui ne contiennent aucun fragment de pierre calcaire, qui ne sont même point unis par un gluten calcaire, ne sont vraisemblablement pas postérieures à la formation des montagnes calcaires, ou du moins ils ne doivent point être confondus avec ces grès et ces poudingues de formation nouvelle, qui entrent dans la composition des montagnes du troisième ordre. «quant aux ardoises que se trouvent interposées au milieu de ces grès et de ces poudingues, § , elles sont de nature argilleuse, et dans l'ordre des pierres que l'on nomme secondaires. «ces ardoises, de même que toutes les pierres de ces montagnes, ont leurs couches dans une situation verticale: mais nous avons vu qu'il y a lieu de croire qu'elles ont été anciennement horizontales.» it is singularly fortunate that such remarkable appearances, as are found in the rocks of this place, had called the attention of m. de saussure to investigate a subject so interesting to the present theory; and it is upon this, as well as on many other occasions, that the value of those observations of natural history will appear. they are made by a person eminent for knowledge; and they are recorded with an accuracy and precision which leaves nothing more to be desired. from _martigny_ to _st. maurice_, about three leagues, there is a most interesting valley of the rhône, through which this river makes its way from the _vallais_, or great valley above, among those mountains which seem to have shut up the _vallais_, and through which the river must pass in running to the lake. m. de saussure found some singular masses, which attracted his attention, in examining the structure of the rocks on the left side of this little valley. like a true philosopher, and accurate naturalist, he desired to compare what was to be observed in the other side of this valley of the rhône, which he had found so singular and so interesting on that which he had examined. accordingly, in spring , he made a journey for that purpose. in this survey he found the most perfect correspondence between the two sides of this valley, so far as rocks of the same individual species, and precisely in the same order, are found upon the one side and upon the other. this author, after describing those particular appearances, sums up the evidence which arises from this comparison of the two sides of the valley; and he here gives an example of just reasoning, of accuracy, and impartiality, which, independent of the subject, cannot be read without pleasure and approbation. but when it is considered, that here is a matter of the highest importance to the present theory, or to any other system of geology, no less than a demonstration that the rocks, of which the mountains on both sides of the valley of the rhône are formed, are the same, and must have been originally continued in one mass, the following observations of our author will be most acceptable to every person who inclines to read upon this subject. «§ . on voit par cet exposé, que bien que la vallée du rlione ait dans ce trajet près d'une lieue de largeur moyenne, les montagnes qui la bordent sont en general du même genre, et dans la même situation sur l'une et l'autre rive. «il y a cependant trois différences que je dois exposer et apprécier en peu de mots. «la plus importante est dans ces couches de pierre calcaire, § , que j'ai trouvées sur la rive droite, et que je n'ai point vue sur la gauche. mais il est possible qu'elles y soient, et qu'elles m'ayent échappé, masquées par des débris ou par d'autre causes accidentelles; cette supposition est d'autant plus possible, que l'épaisseur de ces couches n'est que de quelques pieds. d'ailleurs il arrive souvent, que des filons, tel que paroît être celui dont je parle, ne s'étendent pas à de grandes distances, quoique la nature de la montagne demeure la même. enfin ce qui diminue l'importance de cette différence, c'est que ces couches calcaires se trouvent dans le voisinage de l'ardoise qui passe, comme la pierre calcaire, pour une pierre de nature secondaire, et qui alterne très-fréquemment avec elle. «une autre difference que l'on aura pu remarquer, c'est que sur la rive droite, je n'ai point trouvé de petrosilex pur et en grandes masses, comme sur la rive gauche dans les environs de la cascade. mais cette différence ne me frappe pas non plus beaucoup; parce qu'au lieu de petrosilex, j'ai trouvé sur la rive droite des roches composées en très-grande partie de feldspath. or je regarde le pétrosilex et le feldspath comme des pierres de la même nature. leur dureté est à-très-peu-près la même; leur densité la même, leur fusibilité la même; l'analyse chymique démontre dans l'un et dans l'autre les mêmes principes, la terre siliceuse, la terre argilleuse et le fer; et de plus ces ingrédiens s'y trouvent à très-peu-près dans les mêmes proportions. il ne reste donc de différence que dans la couleur et dans l'agrégation des élémens. or on fait que ces qualités accidentelles tiennent souvent à des causes qui peuvent être purement locales. «la troisième différence, celle qui se trouve dans la direction de quelques-unes des couches, je l'ai déjà indiquée, § . et il semble inutile de répéter, que quand des couches formées originairement dans une situation horizontale, ont été redressées par des opérations violentes de la nature, il n'y a pas lieu de s'étonner qu'elles n'aient pas exactement la même position dans tout l'espace qu'elles occupent. «les différences ne sont donc pas très-significantes, et les ressemblances sont au contraire du plus grand poids. ce qui leur donne à mon gré la plus grande force, c'est la rareté des pierres dont ces montagnes sont composées, ces espèces de porphyres à base de pétrosilex, ces rochers feuilletées mélangées de feldspath et de mica; c'est encore la correspondance de l'ordre dans lequel elles se suivent; ces bancs de poudingues séparés par des ardoises sur une rive comme sur l'autre; leur situation également ou à-peu-près telle. viola de grandes et fortes analogies et qui ne permettent pas de douter que ces montagnes, produites dans le même temps et par les mêmes causes, n'aient été anciennement unies.» having thus shown, that the rhône had in the course of time hollowed out its way from the central mountain of the _st. gothard_ through the extensive valley of the _vallais_ we may still further trace the marks of its operation in the more open country towards the lake. it is an observation which m. de saussure made in his way from the valley of the rhône to geneva. «§ . la grande route de bex à villeneuve suit toujours le fond de la vallée du rhône, en côtoyant les montagnes qui bordent la droite ou le coté oriental de cette vallée. ces montagnes sont en général de nature calcaire, mais on voit à leur pied, jusques auprès de la ville d'aigle, située à une lieue et demi de bex, la continuation des collines de gypse qui renferment les sources salées. «§ . a l'opposite de ces collines, au couchant de la grande route, on voit sortir du fond plat de la vallée deux collines allongées dans le sens de cette même vallée. ces collines sont l'une et l'autre d'une pierre calcaire dure et escarpées presque de tous les côtes. l'une la plus voisine de bex, ou la plus méridionale, se nomme _charpigny_, l'autre _saint tryphon._ «il paroît évident que ces rochers isolés au milieu de cette large vallée sont de noyaux plus dures et plus solides qui ont résisté aux causes destructrices par lesquelles cette vallée à été creusé. ils ne sont cependant pas exactement de la même nature, et surtout pas de la même structure; car celui de _saint tryphon_ est composé de couches régulières, horizontales ou à-peu-près telles, tandis que celui de _charpigny_ a les siennes très-inclinées et souvent dans un grand désordre.» in m. de saussure's journey to the alps, we have now seen a description of the shape that had been given to things, by those operations in which strata had been consolidated and elevated above the sea; nothing but disorder and confusion seems to have presided in those causes, by which this mass of continent had been exposed to the sight of men; and nature, it would appear, had nothing in view besides the induration, the consolidation, and the elevation of that mass into the snowy regions of the atmosphere. from the descriptions now given, we see the operation of the waters upon the surface of the earth; we perceive a regular system of mountains and valleys, of rivulets and rivers, of fertile hills and plains, of all that is valuable to the life of man, and that which is still more valuable to man than life, viz. the knowledge of order in the works of nature, and the perception of beauty in the objects that surround him. let us now turn our view to distant regions, and see the effect of causes which, being general, must be every where perceived. chap. xii. _the theory illustrated, by adducing examples from the different quarters of the globe_ the system which we investigate is universal on this earth; it hangs upon, the growth of plants, and life of animals; it cannot have one rule in europe, and another in india, although there may be animals and plants, the constitutions of which are properly adapted to certain climates, and not to others. the operation of a central fire, in making solid land on which the breathing animals are placed, and the influences of the atmosphere, in making of that solid land loose soil for the service of the vegetable system, are parts in the economy of this world which must be every where distinguishable. but this the reader is not to take upon my bare assertion; and i would wish to carry him, by the observations of other-men, to all the quarters of the globe. mr marsden, without pretending to be a natural historian, gives us a very good picture of the water-worn surface of sumatra. history of sumatra, page . "along the western coast of the island, the low country, or space of land which extends from the sea shore to the foot of the mountains, is intersected and rendered uneven to a surprising degree, by swamps, whose irregular and winding course may in some places be traced in a continual chain for many miles till they discharge themselves either into the sea, or some neighbouring lake, or the fens that are so commonly found near the banks of the larger rivers, and receive their over flowings in the rainy monsoons. the spots of land, which these swamps incompass, become so many islands and peninsulas, sometimes flat at the top, and often mere ridges; having in some places, a gentle declivity, and in others descending almost perpendicularly to the depth of an hundred feet. in few parts of the country of bencoolen or of the northern districts adjacent to it, could a tolerable level space of four hundred yards be marked out: about soogey-lamo in particular, there is not a plain to be met with of the fourth part of that extent. i have often from an elevated situation, where a wider range was subjected to the eye, surveyed with admiration the uncommon face which nature assumes, and made enquiries and attended to conjectures on the causes of those inequalities. some chose to attribute them to the successive concussions of earthquakes, through a course of centuries. but they do not seem to be the effect of such a cause. there are no abrupt fissures; the hollows and swellings are for the most part smooth and regularly sloping, so as to exhibit not unfrequently, the appearance of an amphitheatre, and they are clothed with verdure from the summit to the edge of the swamp. from this latter circumstance, it is also evident that they are not, as others suppose, occasioned by the falls of heavy rains that deluge the country for one half of the year. the most summary way for accounting for this extraordinary unevenness of the surface were to conclude, that in the original construction of our globe, sumatra was thus formed by the same hand which spread out the sandy plains of arabia, and raised up the alps and andes beyond the regions of the clouds." our author then, after reprobating this idea, endeavours to explain the appearance here examined by the constant though imperceptible operation of springs. the present purpose is not so much concerning the explanation of those appearances, as to inquire if these be the general appearances of things over all the surface of the earth. the general appearance here is that of land washed away upon the surface by water, which has every where left the marks of its operation in the shape of the ground. as for any particulars in the shape of this water-worn surface, this can only be explained in knowing the nature of the soil and solid parts, and the circumstances of the operation in which they have been wasted. if the shape of the land here described by mr marsden has been produced by means of water, it must be by water moving from a higher to a lower place; and, in that respect, it is the same operation which every where prevails, in producing similar effects, although it is not every where that this effect comes to be the object of our notice. it is therefore so necessary to illustrate, in giving a diversity of cases. but it is not every case that can be understood as belonging to this rule; for, though the shape of every part has been modified by the operation of this cause, it is not every where that this relation of cause and effect is immediately perceived. there must be a certain regularity in the parts to be described, and a certain conformity wish those in which we have no doubt, or in which we certainly acknowledge the efficacy of the cause. in america, this system of swamps and savannas are to be found upon a large scale; but for this very reason, they are not so remarkable to men. man only sees a system of things, so far as that system is more immediately within the reach of his perception; for, without having prepared _media_, by which he may compare things that are distant either in their nature or their place, how could he judge those things to be connected in a system? it is in this manner that, seeing only the small part of an extended system of things, he sees no system in it, and, consequently he cannot give any scientifical description of the subject. there is another case in which men of science, or systematising men, are apt to fall into delusion: it is not from any deficiency of seeing effects, and knowing general causes; it is from the misapplication of known causes to effects which are perceived. we have a remarkable example of this in the view which m. de bouguer has taken of a singular appearance which he met with, perhaps more interesting to the present theory than almost any other of which we know. (voyage au pérou, page .) «une particularité qui a attiré souvent mon attention dans toutes ces contrées, c'est que toutes les montagnes aupres desquelles je passois, et qui sont au pied et au dehors de la grande cordelière, me paroissoient avoir eu une origine toute différente de celles que j'avois vues auparavant. les lits de différentes terres et le plus souvent de rochers dont elles étoient formées, n'étoient pas inclinés de divers côtés, comme dans les autres: ils étoient parfaitement horizontaux, et je les voyois quelquefois se répandre fort loin dans les différentes montagnes. la plupart de celle-ci ont deux ou trois cent toises de hauteur, et elles sont presque toutes inaccessibles; elles sont souvent escarpées comme des murailles: c'est ce qui permet de mieux voir leurs lits horizontaux dont elles présentent l'extrémité. le spectacle qu'elles fournissent n'est pas riant, mais il est rare et singulier. lorsque le hazard a voulu que quelqu'une fût ronde, et qu'elle se trouvât absolument détachée des autres; chacun de ses lits est devenu comme un cylindre très-plat, ou comme un cône tronqué qui n'a que très-peu de hauteur; et ces différens lits placés les uns au-dessus des autres, et distingués par leurs couleurs et par les divers talus de leur contour, ont souvent donné au tout la forme d'ouvrage artificiel et fait avec la plus grande régularité. il est une de ces montagnes à environ une lieue de honda sur le bord du guali et sur le chemin de mariquita, qui est exposée à la vue de tous les voyageurs; mais je sens que si j'en donnois ici une représentation, il faudroit que je comptasse sur le credit que doit naturellement avoir le rapport de quelqu'un qui n'a aucun intérêt d'altérer la vérité, et qui a en toute sa vie le plus grand éloignement pour le mensonge. on voit dans ces pays là les montagnes y prendre continuellement l'aspect d'anciens et somptueux édifices, de chapelles, de dômes, de châteaux; quelquefois ce sont des fortifications formées de longues courtines munies de boulevarts. il est difficile lorsqu'on observe tous ces objets et la manière dont leurs couches se répondent, de douter que le terrain ne se soit abaissé tout autour. il paroît que ces montagnes dont la base étoit plus solidement appuyée, sont restées comme des espèces de témoins ou de monumens qui indiquent la hauteur qu'avoit anciennement le sol.» there are but two ways in which those appearances may be explained; one of these is that which m. bouguer has adopted; the other, again, belongs to the present theory, which represents the action of running water upon the surface of the earth as instrumental in producing its particular forms, and thus forming many natural appearances upon the surface of the earth. the first of these, viz. that a mass of solid land, in such a shape as that here described, should remain while all around it sinks, is an opinion which, however possible it may be, is not supported, i believe, by any example in nature; the last again, viz. that the parts around those insulated masses, and those that had intervened between the corresponding mountains, have been carried away by the natural operation of the rivers, is not only the most easy to conceive, but is also, so far as those operations are concerned, conform to every appearance upon the surface of the globe. it is not necessary to go to south america, and the rivers of the cordeliers, for examples to illustrate that which every one may see performed almost at his own door; but it is there that an example has occurred, which, though it has imposed upon an eminent philosopher, cannot properly be employed in support of any other theory but the present. our author proceeds: «je ne connois les environs de l'orénoque que par relation, mais je sçais qu'en plusieurs endroits les montagnes y sont également formées de couches horizontales, et qu'elles ont souvent en haut des plateformes qui sont exactement de niveau. on ne trouve à ce que je crois rien de semblable au pérou malgré la variété presque infinie qui y est répandue. toutes les couches y vont en s'inclinant autour de chaque sommet, en se conformant à la pente des collines.» it would appear that it is a rare thing to find a great extent of indurated strata in a horizontal position. now, this circumstance is necessary in affording the appearances here considered; those particular appearances, therefore, are only to be found more partially in other places, where the strata are inclined. if here, therefore, where the strata are horizontal, and where the spaces between the summits of those mountains had evidently been as solid as the masses which remain, we find mountains formed by the waste of land, and a system of rivers forming valleys amidst these mountains, have we not reason to conclude, that in other mountainous regions, where the regular position of the strata has been broken and confounded, and where the same system of river and valley universally is found, the form of the surface has been produced upon no other principle than that of the natural waste of the solid mass, and the washing down of the heights for the formation of the fertile plains? nothing can tend more to illustrate the theory than a proper comparison of the old world with that which is called the new. it is not that we are to expect to see the operation of a longer time, upon the one of those continents, compared with the other; we equally lose all measure of time, in tracing the operations of nature on either continent. but in those operations there is rule to be observed; and the question is, if the same order of things may be perceived in all the quarters of the globe? this is a question which the learned, even, in their closet, may be able to decide. they have but to look at the maps to be convinced that every where the process of nature, in forming habitable countries, is uniform; and that the system of what is called the watering those countries with rivers, is universally the same; a system which is now considered as giving us a view of the operations of water wearing down the land which it has fertilized, and shaping the surface of the earth so as to make it on the whole most useful. there cannot be a doubt of the effects of those natural operations which belong to the surface of the earth, and which affect more powerfully the surfaces of the mountains; the only question is with regard to the general amount of those operations, and to the particular occasions which may have concurred in producing those effects. these questions can only be resolved in making particular observations. a general theory may thus be formed, of those operations by which the surface of the earth above the level of the sea has been changed, and will continue to be so as long as it remains a surface exposed to the influence of those agents which must be acknowledged in this place. naturalists, who have examined the various parts of the earth, almost all agree in this, that great effects have been produced by water moving upon the surface of the earth; but they often differ with respect to the cause of that motion, and also as to the time or manner in which the effect is brought about. some suppose great catastrophes to have occasioned sudden changes upon the surface, in having removed immense quantities of the solid body, and in having deposited parts of the removed mass at great distances from their original beds. others again, in acknowledging the natural operations which we see upon the surface of the earth, have only supposed certain occasions in which the consequence of those natural operations have been extremely violent, in order to explain to themselves appearances which they know not how to reconcile with the ordinary effects of those destructive causes. the theory of the earth which i would here illustrate is founded upon the greatest catastrophes which can happen to the earth, that is, in being raised from the bottom of the sea, and elevated to the summits of a continent, and in being again sunk from its elevated station to be buried under that mass of water from whence it had originally come. but the changes which we are now investigating have no farther relation to those great catastrophes, except in so far as these great operations of the globe have put the solid land in such a situation as to be affected by the atmospheric influences and operations of the surface. the water from the atmosphere, collected upon the surface of the earth, forms channels to itself in running towards the sea or lower ground; and it is these channels, increasing in their size as they are diminished in number by the uniting of their waters, that give so clear a prospect of the operations of time past, and prove the theory of the land being in a continual state of decay, and necessarily wasted for the purpose of this world. every description, therefore, of a river and its valleys, from its sources in the mountains to its mouth where it delivers those waters to the sea, is interesting to the present theory, which is the generalization of those facts by which the end or intention of nature is to be observed. m. reboul, in a memoir read to the academy of sciences at paris in , has given a very distinct view of the _vallée du gave béarnois dans les pyrénées_; there are many things interesting in this memoir; and i shall now endeavour to avail myself of it. «le torrent qui porte le nom de gave de pau parcourt depuis sa source près des limites de l'espagne, jusqu'à la petite ville de lourde, une vallée qui se dirige du sud au nord sur une longueur d'environ dix lieues. cet espace, qui forme son lit dans l'intérieur des pyrénées, ressemble moins à une vallée dans la majeure partie de son étendue, qu'à une entaille étroite et profonde, dont les flancs sont souvent coupés à pic d'une hauteur effrayante, et dont le fond est toujours couvert d'une eau écumeuse. cette long coupure se termine, ainsi que plusieurs de ses branches, aux sommets les plus élevés des pyrénées, et elle reçoit les eaux qui distillent sans cesse de leur neiges durcies. sa division géographique est en deux vallées, dont l'une plus voisine de la plain est appelée lavedan, et dont l'autre ne fait que partie de la contrée qui porte le nom de barèges.» from the summit of that ridge of mountains which run from the atlantic to the mediterranean, the vallies of the principal rivers run from the south northward towards the plain of france; from this again they turn westward in order to find their way to the sea. the mountains, which then separate these rivers from the plain, are composed of schistus and great collections of water-worn gravel which had come from the mountains of the pyrénées. upon this occasion mr reboul observes: «les ruines amoncelées et la grand quantité de cailloux roulés qui forment ces digues naturelles, invitent sans doute à penser que ce sont les torrens eux-mêmes qui ont comblé leur lit et obstrué leur passage, mais on ne peut concevoir que cet effet ait pu avoir lieu que dans des tems très-reculés, et avant l'entière excavation des vallées. peut-être paroîtra-t-il naturel d'imaginer que les masses out été produites par le conflit des eaux qui se précipitoient des montagnes et des flots de la mer, lorsqu'elle recouvroit encore les plaines, etc. «je ne fatiguerai point le lecteur du dénombrement inutile de tous les bancs pierreux de ces substances qui se succèdent le long de la vallée, et prenant seulement le résultat de mes observations, je me bornerai à dire que depuis lourde jusqu'à luz, les parois de la gorge sont alternativement composées de matières argilleuses et calcaires, quelquefois sous la forme de couches diversement inclinées, mais plus souvent fissiles, montrant de feuillets de différentes grandeurs et d'un tissu plus ou moins compacte. ces schistes hétérogènes sont presque toujours entassés et superposés dans la même montagne, mais en plusieurs endroits un seul genre prédomine, etc. l'espèce d'uniformité qui semble exister dans la composition de ces masses, ne se trouve nullement dans leurs disposition; on chercheroit en vain dans leurs couches une direction et une inclinaison générale et constante, on pourroit tout au plus hazarder à ce sujet de légères conjectures; mais si l'ordre primitif de ces montagnes est dérobé à l'oeil de l'observateur, on trouve à chaque pas des indices certains, des marques évidentes de la manière dont il a été altéré ou détruit. «je reconnus d'abord que les mêmes cailloux, les mêmes débris de marbre et d'ardoise qui couvraient le fond de la vallée, et que le gave entraîne et remplace sans cesse, se trouvent aussi à plusieurs toises au-dessus de son niveau. je voyois quelquefois les sédimens fluviatiles recouverts et ensevelis sous des grandes masses de pierre feuilletée adhérente à la montagne; levant ensuite les yeux, j'observai que de l'un ou de l'autre côté du torrent, les flancs des montagnes étoient souvent couverts et comme plaqués de semblables masses de schiste, dont les couches et les feuillets offroient toujours des directions contraires à celles des schistes de même nature, auxquels ils étoient adossés. les eaux du torrent, qui ont sans doute renversé ces couches sur elles-mêmes, y ont déposé des marques de leur passage; elles ont abandonné, engagé sous ces débris mêmes, à des grandes hauteurs, des blocs énormes de granit que le voyageur surpris voit pendre sur sa tête; de pareils blocs arrondis et usés couvrent le fond de la vallée, et opposent quelquefois au torrent une digue qui le fait jaillir et retomber en écume; enfin j'ai suivi les traces de ce courant aux différentes hauteurs des parois du canal où il coule aujourd'hui à plusieurs centaines de toises de profondeur. il a dû les parcourir toutes successivement en creusant et rétrécissant sont lit et augmentant sa vitesse. «les crêtes des sommités qui forment les bords les plus élevés de la gorge, sont escarpées dans la direction du courant. j'ai aperçu quelquefois des portions de montagnes séparées de la crête, ou du sommet principal, et dont les eaux semblent en avoir fait des espèces d'îles, en creusant autour d'elles un fossé profond, où l'on voit fort bien les angles saillans de l'île correspondre aux angles rentrans de la montagne, etc. «dans la partie de la vallée où s'observent ces phénomènes, on marche toujours entre deux montagnes resserrées, dont les nuage dérobent souvent les cimes, mais par-tout où les eaux de quelque torrent considérable viennent se réunir à celles du gave, il s'est formé un bassin d'une étendue moyenne, qui ne fut d'abord vraisemblablement qu'une grande mare d'eau semblable à ces lacs qui existent encore dans le sein des pyrénées et des alpes. ainsi on voit, à une lieu avant argelès, les montagnes s'écarter, se replier en un vaste circuit, et entourer, comme d'une muraille stérile et ruineuse, des prairies arrosées par mille canaux et par le brouillard des cascades; des coteaux, où l'on voit s'élever, parmi les vergers et les bois, des villages ornés de marbre, des châteaux majestueux et les délicieuses habitations de quelques moines fortunés. «le penchant qui borde ce vallon du côté de l'est n'est creusé que par quelques ravins très-inclinés, dont les eaux se précipitent en écume et disparoissent, avant d'arriver au bas de la montagne, sous l'ombre des bois et d'une foule d'habitations rustiques: mais le penchant de l'ouest, plus profondément excavé par les torrens, présentent les issues de trois autres vallées, dont les deux principales vont prendre leurs origine aux limites de l'espagne; l'autre, plus voisine de la plaine, est à-peu-près dirigée de l'est à l'ouest. elles s'appelle _estrem de sales_, et joint ses eaux à celles du gave un peu au-dela de l'extrémité intérieure de ce grand bassin qu'elle a concouru à former. c'est au centre du bassin, auprès du village d'argelés, que le gave d'azun arrive avec fracas, et c'est à son extrêmité supérieure que le gave de cautrês s'y précipite en sortant d'une gorge dont l'aspect frappe d'étonnement et d'horreur. le cours de ces deux gaves est auprès de leur embouchure oblique à celui du gave principal; mais ils se replient ensuite vers le centre de la chaîne et deviennent presque parallèles. auprès de luz se découvre un autre bassin où se joignent les eaux du gave à celles du torrent de la lise, qui n'a creusé qu'un ravin, et à celles du bastan qui descend d'un vallon très-évasé dans la direction de l'est à l'ouest, où se trouvent les eaux minérales de barèges. ce nouveau bassin n'offre que le spectacles d'une vaste prairie bordée de montagnes prodigieuses. je n'entreprendrai point de rien ajouter ici touchant ces diverses branches de la vallée du gave béarnois; chacune d'elles exigeroit une description détaillé, soit à cause de son étendue, soit à cause de la variété de ses phénomènes. «de luz à gavarnie le gave se trouve de nouveau resserré dans une gorge étroite où les montagnes paroissent encore s'élever et les abîmes s'enfoncer; ses eaux ne coulent plus qu'en cascades bruyantes, et quelquefois le voyageur, qui les voit écumer sous ses pieds du haut du sentier tracé sur la montagne, entend à peine un murmure lointain. on y remarque de nouveau les phénomènes, décrit ci-devant, des pierres feuilletées renversées de leur première direction, des bancs entiers courbés et brisés dans leur chûte, des débris granitiques arrondis par les eaux, déposès à de très-grandes hauteurs dans le fond des ravins où le courant n'existe plus, etc. «a gèdre le gave reçoit les eaux de héas, lieu devenu célèbre et enrichi par la dèvotion espagnole. a peine a-t-on passé le torrent, que le granit commence à paroître. le gave roule ses eaux sur cette base qu'il entame difficilement: aussi son lit est-il plus large et la gorge moins profonde: le granit se montre enterré sous de grandes montagnes calcaires. du côté de l'ouest il est presque toujours recouvert de ces masses qu'on distingue de loin à leur teinte grise et blanchâtre mêlée de sillons d'un rouge peu foncé. a l'est les montagnes calcaires laissent le granit à découvert, et lui demeurent comme adossées. celles qui leur succèdent offrent des marques, effrayantes de décrépitude; leurs crêtes sont démantelées, et leurs flancs sont lésardés et hérissés de rochers suspendus. le fond de la vallée semble enseveli sous les débris de cette montagne à demi écroulées. on trouve, parmi les ruines, des blocs de plusieurs milliers de pieds cubes. le gave les couvre quelquefois de ses eaux, se précipite dans les intervalles qu'ils laissent entr'eux, et renaît comme sous une voûte affaissée. plusieurs de ces lambeaux affectent sur leurs plans la forme de parallélogrammes et de rectangles; mais ceux que l'on voit encore attachés au corps de la montagne, sont pour la plupart pyramidaux, et sa crête est formée d'une suite de ces pyramides granitiques. toutefois on ne peut pas se refuser à voir que le granit est ici disposé en couches très-distinctes qui paroissent surmontées dans quelques points des sommités, de bancs calcaire. la direction de ces couches granitiques n'est pas constante dans toute la masse; elles semblent s'incliner vers le sud-ouest du côté de gavernie, et vers le nord-est du côté de gèdre. quoique leurs substance soit mêlées de plusieurs roches hétérogènes, elle est généralement composées de quartz, de feld-spath, et de mica; mais ces deux substances y sont dans un état frappant de décomposition, et semblent quelquefois réduites en chaux de fer. «au-delà de leurs débris, dont l'amas est désigné par le montagnards sous le nom de _peyrade_ et sous celui de _catios_ par les gens du monde, le granit est de nouveau surmonté de substances calcaires. il sort de base aux pics coniques de caumelie et de pimené. cette base forme elle-même une vaste montagne qu'on appelle _allans_; ses roches, d'un granit ferrugineux et sombre, sont entourées d'une couronne blanchâtre et calcaire, où végètent quelque sapins épars: gavarnie est à ses pieds. «c'est à une légère distance de ce village, que se termine la vallée du gave béarnois, ou plutôt qu'elle prend naissance avec le torrent qui l'a formée. on apperçoit de loin les vastes sommets et les champs élevés de neige et de glace d'où ses eaux se précipitent; on reconnoît ensuite qu'ils ne forment qu'une montagne ou plutôt une masse énorme par sa hauteur et son volume, composée d'une même matière, et qui, placée sur une base vers laquelle on n'a cessé de monter pendant l'espace de dix lieues, s'élève tout-à-coup de sept à huit cens toises, et domine au loin toutes les montagnes qui l'entourent. les différens sommets dont elle est couronnée se présentent sous mille formes bizarres; ce sont des pyramides irrégulières et de vastes cylindres, ou de cônes tronqués près de leur base, qui ressemblent assez à des tours écrasées. les crêtes, qui sont formées du prolongement de ces sommités, sont autant de murailles inaccessibles bordées d'un long tas de ruines ou d'un large fossé de neige glacée, et quelquefois interrompues par de brèches profondes. on ne peut apercevoir tous ces objets du fond de la vallée, et il faut s'élever sur quelque hauteur voisine, telle que le sommet de bergons, ou celui de pimené, pour embrasser toutes les parties de ce vaste tableau. en remontant vers les sources du gave, qui en occupe le centre, on pénètre par un coupure peu profonde dans une prairie de forme ovale assez régulière bordée à l'est et à l'ouest par des hauteurs plantées de sapins et de hêtres, et au sud par un amas de rochers écroulés, et par les sommets que je viens de décrire. le gave y serpente sur un lit de sable et de cailloux, et reçoit les eaux qui descendent, en écumant, des hauteurs voisines; il se fraie un chemin vers cette prairie parmi les débris entassées qui la bornent au sud, et qui la séparent d'une autre bassin non moins vaste, où le torrent commence son cours, et où la montagne s'élève tout autour en un rempart inaccessible. «on peut prendre une idée légère et imparfaite de cette majestueuse enceint, en se la figurant comme un amphithéâtre moins remarquable par la vaste étendue de son arêne que par la hauteur prodigieuse de ses murs qui, par-tout bordés de parties saillantes, d'échancrures profondes, et hérissés de rochers dont la ruine est prochaine, se sont entièrement écroulés du côté du nord; elle-est couronnée vers le sud par deux sommets cylindriques recouverts d'une croûte épaisse de neige durcie, et que leur forme a fait nommer tour de marbre. au-dessous se succèdent, en forme de gradins, de vastes platte bandes d'une neige qui ne disparoît jamais, et qui ne cesse point de se fondre insensiblement. les eaux produites par cette stillation continuelle se divisent en sept ou huit petits torrens qui naissant sous ces lits de glace, et roulent sur le penchant rapide de la montagne ou jaillissent en cascades, quand elle se trouve coupée a pic. l'un de ces torrens venant du côté de l'est et dont le volume surpasse celui de tous les autres ensemble, se précipite du haut d'un rocher qui s'avance en saillie, et tombe avec un bruit horrible à plus de pieds de profondeur. ses eaux, divisées dans les airs et réduites comme en poussiere, forment autour de la cascade un brouillard suspendu qui dérobe aux yeux du spectateur tout son volume et la vitesse de sa chute. l'arène ou se réunissent toutes ces eaux et où commence le gave, est de forme irrégulière; sa surface inégale offre tantôt de grands plateaux de neige, des blocs de rochers écroulés et d'autre débris atténué et réduits à l'état terreux où végètent de belles plantes que le soleil éclaire à peine. le gave, en tombant sur les amas de neige, y a creusé un gouffre au fond duquel le soleil avant son déclin peint le cercle coloré de l'iris. les eaux disparoissent sous la neige et renaissent ensuite comme sous un pont étroit ou sou la voûte d'un aqueduc; elles serpentent, se replient à travers les ruines amoncelées, et surmontent les obstacles qui s'opposent à leur sortie. «si l'aspect magnifique et la beauté sauvage de cette enceinte sont difficiles à représenter, sa structure n'en est pas moins facile à saisir; et dans ce lieu, qui semble fait pour le tourment du peintre de la nature, elle se découvre sans peine au yeux de l'observateur et de l'historien. _la grande enceinte de la cascade de gavarnie_, dit m. d'arcet, _fut un lac autrefois: l'aspect des lieux fait naître naturellement cette idée. dans la suite les rochers qui la fermoient sur le devant, s'étant détruits, les eaux se sont écoulées et perdues_. «on ne peut se refuser à croire avec m. d'arcet, que l'enceinte des cascades de marbre n'ait été autrefois un lac. le nombre et l'étendue de ces amas d'eau diminuent tous les jours dans les pyrénées comme dans tout pays de montagnes; les eaux qui viennent s'y rendre en exhaussent le fond par les cailloux et les débris terreux qu'elles y entraînent, et celles qui s'écoulent en abaissent le niveau, en creusant insensiblement le canal par lequel elles sortent. ainsi la marche lente et progressive de la nature sans l'intermède des accidens et de révolutions, suffit pour combler ces vastes creuse où les eaux se sont amassées, ou pour ouvrir des issues qui ne leur permettent plus d'y séjourner. le nombre de ces lacs abandonnés et perdus n'est guère au-dessous de celui de lacs encore existans. les naturels du pays ont appris eux-mêmes à distinguer ces monumens naturel; ils ont saisi leur structure semblable à celle d'un vaisseau évasé et coupé dans ses parois d'une ou de plusieurs entailles profondes, et les ont tous désignés par le mot _oule_, qui dérive du mot latin _olla_, et signifie chez eux marmite; comparaison aussi juste que peu noble et bien digne de ces observateurs froids, mais exacts, également dépourvue de prévention et d'enthousiasme. ces _oules_ se trouvent souvent placées aux extrêmité supérieurs des vallées, à l'origine des torrens qui les remplissoient autrefois. en effect, ceux-ci naissent communément sous quelque vaste amas de neige, ou s'écoulent d'un réservoir qui rassemble les eaux des hauteurs voisines. le nombre de ces lacs augmente à mesure qu'on s'élève, et c'est une observation générale, que ceux des vallées sont pour la plupart comblés ou perdus, et que ceux des montagnes, surtout de celle de granit, sont presque tous conservés. j'ai dit précédemment, d'après l'observation de m. d'arcet, que l'enceinte des cascades présentoit la forme d'un réservoir entr'ouvert et épuisé, et qu'elle étoit précédée d'un autre bassin dont l'aspect est moins sauvage et la forme plus régulière. tout porte à penser que celui-ci a été aussi long-tems rempli d'eau, ou plutôt il résulte d'un examen détaillé de ces lieux, que le deux bassins ne faisoient autrefois qu'un seul et immense réservoir, où les eaux étoient retenues à deux ou trois cens toises d'élévation au-dessus du sol où elles coulent aujourd'hui. les rochers qui séparent le premier bassin de l'enceinte des cascades, ne sont, comme je l'ai déjà remarqué, qu'un vaste amas de débris; mais ces débris ne ressemblent point à ceux d'une muraille renversée sur elle-même, ou d'une digue rompue par l'effort des eaux. il est au contraire aisé de se convaincre qu'ils ont été détachés de cette partie de la montagne qui bord l'enceinte du côté de l'est, et sur laquelle sont les sommets les plus élevés de toute cette masse. on voit encore sur ses flancs déchirés pendre d'énormes quartiers de roche prêts à s'écrouler. ceux qui sont déjà tombés ont demeuré entassés les uns sur les autres. l'amas qu'ils ont formé est adossé à la montagne dont ils faisoient jadis partie, et s'incline jusqu'aux parois opposée de l'enceinte. le torrent qui la traverse se trouve ainsi rejeté du côté de l'ouest, et le lit qu'il a creusé suit les contours de cet amas de débris. un tems a donc existé auquel les deux enceintes dont j'ai parlé, étant remplies d'eau, ne formoient qu'un seul lac vaste et profond; et peut-être la même révolution qui les a séparées a-t-elle changé tout-à-fait leur forme et causé l'entière dispersion de leurs eaux; car si l'on considère que l'enceinte du bassin de la prairie est entièrement détruite du côté du nord et de la vallée, on doit se convaincre que les eaux ne l'ont point corrodée lentement, mais qu'elles l'ont entrouverte et emportée par un effort violent et subit. or à quelle cause peut-on mieux attribuer le mouvement rapide et le choc qui dut les agiter, qu'à la chute instantanée de plusieurs milliers de toises cubes de rocher. je me représente alors ce lac paisible et élevé changé en une mer courroucée, ses eaux bouleversées jusqu'au fond de ses abîmes jaillir au-dessus des sommets voisins, et retombant sur elles mêmes ébranler de leur poids et de leur chute la barrière qui les retenoit, cette barrière trop foible enfin renversée et ses débris transportés au loin. «m. d'arcet, dans son discours sur les pyrénées, a présagé la même révolution pour le lac d'escoubons le plus considérable de ceux qui dominent les bains de barèges, et on ne peut douter que si quelqu'éboulement considérable vient hâter et accroître l'effet de cette débâcle inévitable, ces régions élevées subiront un nouveau déluge dont les hommes et les troupeaux seront la victime, qui ensevelira plusieurs villages, et inondera les tanières des bêtes fauves.» m. reboul has here imagined to himself the former existence of an immense deep lake, which, no doubt, is a thing that may have been, like many others which actually exist. but then he likewise supposes a particular revolution of things, in which one side of that stony circuit, forming the bason of the lake, had been destroyed while the water was discharged. it is this last hypothesis which appears to me to be a thing altogether inadmissible, according to the natural order of things. in order to see this, it must be considered, that the side of the bason, which has disappeared, must have been either of similar materials to those which we see now remaining, or it must be supposed as composed of loose materials, such as had been more soft, or of those that might be easily dissolved and washed away by the water. if this last had been the state of things, there would not have been occasion for any violent catastrophe, as m. reboul has supposed; the natural overflowing of the lake had been sufficient to wear the mound by which the water had been detained, and to carry away those materials so as one side might disappear. if, again, this mound had been formed of rock, like what remains of those mountains, in that case, the catastrophe, which this author has suggested as the cause of that destruction, would have been ineffectual to procure that end; for, though such a _débacle_ might have carried away a great mass of loose materials, it could not have moved a mound of solid rock. that of which we have here undoubted information, and that which i am labouring to generalise by comparing similar phenomena, such as are to be found over all the earth, is this, that the natural operations of the atmospheric elements decompose the solid rocks, break down the consolidated strata, waste and wash away those loosened materials of the mountains, and thus excavate the valleys, as the channels by which an indefinite quantity of materials are to be transported to the sea for the construction of future continents. it is this operation of nature which we see performed, more or less, every day, which some natural philosophers have such difficulty in admitting at all, and which others overlook in seeking for some wonderful operation to produce the effect in a shorter time. the prodigious waste that evidently appears, in many places, to have been made of the solid land, and the almost imperceptible effects of the present agents which appear, have given, occasion to those different opinions concerning that which has already happened, or that natural history by which we are to learn the system of this world. the object which i have in view, is to show, first, that the natural operations of the earth, continued in a sufficient space of time, would be adequate to the effects which we observe; and, secondly, that it is necessary, in the system of this world, that these wasting operations of the land should be extremely slow. in that case, those different opinions would be reconciled in one which would explain, at the same time, the apparent permanency of this surface on which we dwell, and the great changes that appear to have been already made. now if, in the indefinite course of time, (which we cannot refuse to nature, and which is only to be traced in those effects), the chymical and mechanical operations of the surface are capable of diminishing the mass of land above the level of the sea, (of which fact the appearances here so well described by m. reboul, and those which are every where else to be observed, leave no room to doubt); and, if the wise system, of a world sustaining plants and animals, requires the long continuance of a continent above the surface of the sea, what reason have we to look out for any other causes, besides those which naturally arise from that constitution of things? and, why refuse to see, in this constitution of things, that wisdom of contrivance, that bountiful provision, which is so evident, whether we look up into the great expanse of boundless space, where luminous bodies without number are placed, and where, in all probability, still more numerous bodies are perpetually moving and illuminated for some great end; or whether we turn our prospect towards ourselves, and see the exquisite mechanism and active powers of things, growing from a state apparently of non-existence, decaying from their state of natural perfection, and renovating their existence in a succession of similar beings to which we see no end. we have been comparing similar operations of nature in different countries; but at present we have something farther in our view than to compare the distant regions of the earth. we want to see if it be the same system that is observed in the higher regions of the globe as in the lower. we shall thus have investigated the subject as far as we can go. the high region of the andes and cordeliers affords an opportunity of deciding that question. it is there that we find a habitable country raised above the rest of the earth. it is there that nature, in elevating land, has proceeded upon a larger scale. here, therefore, in the operations of water upon the surface of the earth, we are to look for effects proportioned to the cause. let us cast our eye upon the southern continent of the new world; there is not, from the one end to the other, any great river that flows to the sea upon the west side. a ridge of mountains, at no great distance from the coast, divides the water of this continent; a small part runs to the west; the most part runs to the east; and forms a country which, for fertile plains and navigable rivers, has not its equal upon the globe. but let us observe the course of the rivers; while confined by the ridges of the andes and cordeliers; they run either south or north, and are thus for some time constrained to take a course very different from that which they are afterwards to pursue. it is while thus retained within the ridges of the andes that those rivers water plains which they had formed; and it is here that we find countries so much elevated above the rest of the world, that, under the direct rays of the sun, their inhabitants are made to suffer from the cold. it is the collection of those waters running from south to north, and descending from an enormous height, that have formed in the plain those appearances that struck so much the french philosopher, as to make him give us a detail, which, though out of his line, is extremely interesting in the natural history of the earth. it is in the valley of the madelena that m. bouguer found those grand relicts of the wasted strata; but we are now to take a view of a country situated high above the level of that valley. it is that of santa fée de bogota; a fertile plain estimated at toises, almost about two miles above the level of the sea; and which pours its water into the valley of the madelena about a degree above honda, which is mentioned by m. bouguer as giving so fine an example of those water-worn rocks. the extreme singularity in the situation of this country, and at the same time the perfect similarity which is here to be observed of this country with all the rest of the earth, as the work of water, will excuse my transcribing from m. le blond, _(journal de physique,_ mai ) what i judge to be interesting to my readers. «si un observateur attentif parcourt les plaines immenses de l'amérique méridionale, s'il monte les fleuves rapides et profonds qui les traversent, et les inondent, et s'il franchit les montagnes prodigieuses que l'action des eaux détruit, il apercevra bientôt qu'un développement successif et inévitable de ce nouveau continent tend à l'agrandir dans tous les sens, et rendra peut-être un jour sa surface égale à celle de notre hémisphère. «il est des sites dans les montagnes des cordillères ou des obstacles plus ou moins puissant retardent cette même dégradation: la plaine de santa fée de bogota est entre ces sites celui qui m'a paru le mieux caractérisé et le plus frappant. il sera l'objet de ce memoire: on verra avec surprise qu'un pays sain, agréable, abondant, et fertile aujourd'hui, étoit autrefois le plus dépourvu et le plus misérable du monde, ou l'indien malheureux n'avoit pour tout bien que des rivieres sans poissons, des oiseaux en petit nombre, un quadrupéde ou deux, et quelques légumes; on sera étonné d'apprendre qu'une temperature froide environnée d'un climat brûlant, fut une barrière insurmontable pour presque tous les animaux et les plantes des pays chauds. la nature agresse et avare de ses dons sembloit en rejeter l'homme, et vouloir y être en quelque sorte séparée du reste du monde par des rochers énormes, coupés verticalement, qu'on ne parvient à franchir qu'avec des difficultés étranges à travers un brouillard humide et ténébreux, qui persuade au voyageur fatigué qu'il travers la région des nues. «arrivé au haut de ces montagnes, un nouveau ciel, un nouvel ordre de choses se présentent; ce ne sont plus ces insectes degoûtans et insupportables qui le fatiguoient sans relâche; ces reptiles venimeux, dont il redoutoit la morsure; ces bêtes féroces toujours prêts à le dévorer; enfin, cette, chaleur suffocante des lieux bas qu'il vient de quitter; l'air qu'il respire rafraîchit et le vivifie; il s'arrête, et ce qui l'environne l'étonné et le ravit; s'il regarde au-dessous de lui, tout est éclipsé par des nuages, dont la surface égale mouvante lui représente une mer qu'habite le silence et que termine son horison; s'il jette la vue sur la plaine qui se perd devant lui, les nues qu'il croyait sous ses pieds, roulent majestueusement sur sa tête; de nouvelles montagnes s'élèvent de toutes parts, et forment un nouveau monde qui paroît indépendant du premier. «pour donner une idée exacte de ce pays singulier, j'ai cru devoir transporter le spectateur à la capitale, où de là comme d'un centre, il pût observer plus commodément les phénomènes que j'ai à lui presenter. «la ville de santa fée de bogota, capital du nouveau royaume de grenade, a environ degrés de latitude n. et de longitude, prise de l'île de fer, est située au pied et sur le penchant d'une montagne escarpée qui la couvre à l'est; elle domine une plaine de douze lieues de largeur sur une longueur indéterminée et très considérable, qui présente toute l'année le riant tableau des plus belles campagnes de l'europe: les coteaux toujours verts où les troupeaux bondissent, les prairies couverts de bétail, les champs bien cultivés, les maisons de campagne agréables, les hameaux, les villages, les vergers, les jardins, montrent à la fois, les fleurs du printemps et les fruits de l'automne, que l'abondance des pluies ou les sécheresses retardent ou avancent quelquefois mais dont l'éternelle durée bien loin d'inspirer le plaisir, et d'offrir l'attrait piquant de la nouveauté qui fait le charme de ces saisons dans nos climats, amène bientôt l'indifférence pour une beauté toujours le même, pour des agrémens qui ne changent pas. «ce climat est d'ailleurs si étrange et tellement constitué, que quand on est au soleil, on se trouve bientôt incommodé de sa chaleur; est on à l'ombre? on se sent pénétré d'un air subtil et froid qui transit. «a trois lieues à-peu-près à l'ouest de la ville, passe la rivière de bogota qui, après avoir reçu les eaux de toute la plaine, la rivière de serrefuela et les torrens qui se précipitent de la chaîne de montagnes, dirige son cours paisible vers tekendama à sept ou huit lieues au sud-est à-peu-près; c'est-là que ces eaux rassemblées coulent entre une suite de rochers granitiques, dont le plain incliné accélère leurs vitesse; elles n'offrent bientôt plus qu'un courant rapide, étroit et profond qui, au moment de sa chûte, rejaillit sur un rocher placé plus bas que son lit, d'où il tombe dans une abîme dont on n'a pu jusqu'ici mesurer la profondeur; c'est la cataracte ou saut de tékendama. «des trous pratiqués dans le roc par les anciens aux endroits les plus commodes pour voir toute l'étendue de cette chûte prodigieuse, donnent le moyen d'observer sans risque la continuation des rochers qui s'avancent à droite et à gauche et annoncent par leurs hauteur qu'avant le passage que les eaux semblent avoir forcé, la plain de santa fée n'étoit alors qu'un lac d'une très-grand étendue: une tradition constante du pay, mais peu vraisemblable, porte que les indiens ont creusé cette espèce de canal. «il y a quelques-uns de ces trous d'où l'on voit confusément le lieu où finit cette chûte d'eau effroyable; la rivière qui en provient n'offre plus qu'un foible ruisseau, dont le cours presqu'insensible se perd parmi les plantes qui croissent sur ses bords; ainsi disparoissent dans l'éloignement les masses les plus énormes: quelques espèces de perroquets et d'autres oiseaux de pays chauds, qui habite cette vallée profonde et inabordable de ce côté, s'élèvent assez quelquefois pour pouvoir être remarqués d'en-haut; mais le froid subit de ces montagnes qu'ils craignent, est une obstacle invincible qu'ils ne franchissent jamais: pour jouir commodément de ce point de vue, à la fois admirable et effrayant, il faut choisir un jour calme et serein, entre sept à huit heures du matin. «il est necessaire de prendre un long détour et cheminer pendant toute une journée, presque toujours à travers des rochers et des précipices, pour parvenir au pied de cette cataracte; on est alors étrangement surpris de voir que cette rivière à peine sensible d'en haut, soit encore un torrent prodigieux, dont la chute en cascades dans une angle de degrés, offre pendant l'espace d'une grande demie lieue des amas de rochers entassés au hazard, que frappe et détruit sans relâche le plus bruyant conflict des eaux; c'est après cet espace que le courant, devenu plus paisible permet encore de comparer la rivière de bogota à ce qu'est la seine dans l'été. «un phénomène bien extraordinaire et qui sert en même tems à donner la plus haute idée de l'étendue prodigieuse de cette cataracte, c'est que sa chute commence dans un pays très-froid où il gèle souvent pendant la nuit, et finit dans un autre où la chaleur, égale à nos beaux jours d'été, offre la végétation prompte et facile de toutes les plantes des pays chauds: seroit-ce le passage subit de l'air du chaud au froid qui occasionneroit ces gelées blanches, à-peu-près comme celles qui ont lieu dans nos climats aux approche de l'hiver et à l'entrée du printemps? car on en éprouve rarement dans la plane. «une autre particularité remarquable de ce pays, c'est le défaut de poisson dans toutes les rivières qui l'arrosent: on en trouve cependant dans celle de bogota où les autres rivières viennent se rendre; mais c'est une seule espèce très-peu abondante, que les espagnols appellent el capitan, ou le capitaine; la plus grande longueur de ce poisson est d'environ un pied, sur six pouces de grosseur; il vit dans les eaux troubles et vaseuses de cette rivière, et jamais dans les eaux claires; il est gras et excellent à manger: son genre est celui de la _mustelle fluviatile de france_ et le _gades_ de linné. «il est certain cependant que les poissons de toutes les sortes abondent dans les grandes rivières de l'amérique méridionale et notamment dans celle de la magdelaine; ne pourroit-on pas supposer d'après cela, que puisque toute communication des eaux de tout le pays élevé de santa fée est interrompue avec cette dernière par le saut de tekendama, ces mêmes eaux n'ont pu en être peuplées comme celle-ci paroissent avoir été, au moins en partie, par la mer. ce même défaut de poisson se remarque dans la plus part de lacs et des rivières des cordillères, probablement par une cause semblable; il n'y en a point dans les deux lacs assez étendus qui sont près de la ville d'hyvarra dans la province de _quito_, non plus que dans les rivières de la province de pastos. «on peut objecter qu'une temperature toujours froide comme celle de santa fée, joint à la limpidité et la rapidité des torrens des cordillères, suffisent pour écarter les poissons, de même que cela arrive dans plusieurs rivières de l'europe. «cette objection seroit vraie pour la plupart des torrens des cordillères, mais on observera que la rivière de bogota quoique froide, est presque stagnante dans bien des endroits, et coule toujours sur de la vase qui en rend les eaux bourbeuses; il est à présumer que, s'il étoit possible d'y tranporter des poissons de nos rivières, ils y réussiroient aussi bien que les autres productions de l'europe qui se sont naturalisées dans ce pays. quant à la température constante froide de ces eaux, qui pourroient paroître s'opposer au développement des oeufs du poisson qui habite les rivières des pays chauds, on y respondra par le fait suivant. «a vingt lieues environ au nord de santa fée à la même élévation et à la même température, est un grand lac où l'on trouve des îles habitées, et qui en a paru assez grand pour être indiqué dans les cartes géographiques, si on en savoit les dimensions; c'est le lac de chiquinquira assez poissonneux pour y faire des pêches abondantes, parce que la rivière qui en sort n'est pas interrompue par des sauts dans son cours jusqu'à la rivière de la magdelaine; cependant les espèces de poissons qu'on trouve dans ce lac ne sont pas aussi variées que dans cette grande rivière, sans doute à cause de la rapidité du courant, que le poisson ne remonte pas également bien. «lorsqu'on gravit sur les montagnes escarpées qui dominent la ville de santa-fée, on ne rencontre, depuis leur base jusqu'à leurs sommets, terminés par des rochers de granité, que des bruyère, des fougères, quelques plantes sauvages, etc. et pas un arbre qu'on puisse seulement appeler un boisson excepté dans quelques gorges à l'abri de courans d'air, où l'on en voit quelques-uns dont les plus grands, n'égale pas nos prunières; cette végétation engourdie paraît être due au froid vif et continuel qu'il fait sur ces montagnes; car plus on monte, moins elle se développe, et enfin finit par cesser tout-à-fait: on remarque à la moitié de la hauteur d'une de ces montagnes (à une demi-lieue à peu-près de la ville) une mine de charbon de terre en filon que renferme une rocher entrouvert, dans une situation verticale[ ], les torrens y roulent de l'or.» [footnote : here is an evidence that those vertical strata, now elevated into the highest stations upon the earth; had been formed originally of the spoils of the land, and deposited at the bottom of the sea.] «si l'on descend dans la plaine, si l'on remonte sur les collines, toutes à-peu-près de la même hauteur qui sont entièrement séparées des montagnes voisines, et situées dans la direction ou courant des rivières, on remarque aisément qu'elle sont les restes d'une plaine antérieure que les eaux ont dégradée. au lieu de ces forêts, et de ces boissons qui surchargent bientôt nos campagnes lorsque la main de l'homme cesse de les cultiver, un gazon touffu couvre la plaine et les collines de santa-fée d'une verdure agréable sans nul arbrisseau qui puisse en altérer l'uniformité, où les graminée, le plantain, le scorçonnaire, le trèfle, le marrube, la pimprenelle, le pourpier, la patience, le chardon, le raifort, le cresson, la chicorée sauvage, la jonquille, la marguerite, le fraisier, la violette, le serpolet, le thym, et mille autres plantes d'europe et particulières à ce pays, offrent les variétés les plus piquantes par la beauté des fleurs et i'odeur de leurs parfums; des rochers qu'entourent le rosier ou la ronce, et quelques cavernes que le hazard presente sur ces mêmes collines, en rendent l'aspect pittoresque et délicieux.» here is a picture of a country such as we might find in europe; only it is placed under the line, and elevated above the highest of the frozen summits of the european alps. we may observe that the same order of things obtains here as in every other place upon the surface of this earth; mountains going into decay; plains formed below from the ruins of the mountains; these plains ruined again, and hills formed in their place; rivers wearing rocks and breaking through the obstacles which had before detained their waters; and a gradual progress of soil from the summits of the continent to the border at the sea, over the fertile surface of the land, successively destroyed and successively renewed. here are to be observed two states of country along side of each other, the plain of the bogota, and the valley of the madalena. the courses of the two rivers show the direction of those ridges of mountains which had been raised from the deep; they run south and north, as do those valleys which they drain. at this place we find the valley of the river cauca, and the valley of the magdalena parallel to each other, and also to this high plain of the bogota. now the waters of this high country, instead of running northward to the sea, as do those of the two valleys below, run both from the south and north until, uniting together, they proceed westward, break the rampard of granite rocks at tekendama, and fall at once from the high plain down into the valley of the madalena. those water formed plains which we perceive subsisting at unequal levels immediately adjoining to each other, while they present us with a view of the degradation of the elevated earth, at the same time illustrate the indefinite duration of a continent; for, we judge not of the progress of things from the actual operations of the surface, which are too slow for the life of man, and too vague for the subject of his history, but from the state of things which we contemplate with a scientific eye, and from the nature of things which we know to be in rule. in like manner the horizontal situation of the solid strata in the mountains of that low country, while those of the high country are more or less inclined, afford the most instructive view of the internal operations of the globe, by which the andes had been raised from the bottom of the sea, and of the external operations of the earth by which mountains are formed by the wasting of the elevated surface. with this description of those high plains upon the north side of the line, let us compare what d. ulloa has said upon the same subject in describing the continuation of that high country to the south. i shall give it from the best french translation. it is after describing a cut or narrow ravine in the solid rock with perpendicular sides, about forty yards deep, in which a rivulet runs and the road passes. «cette excavation est, en petit, une modèle des vastes _quebradas_ ou profondeurs, et fait comprendre leur origine: elles ne pouvoient être que semblables à celle-ci: tout s'y est passé de même, ou plus tôt ou plus tard. les flancs en ont été plus ou moins perpendiculaires, jusqu'au moment où ils se sont affaissées, et ont formé des plains inclinés, lorsque l'eau faisant de plus profondes excavations, eut miné la base qui les soutenoit. ne pouvant plus alors persévérer dans leur premier état, les terrains ont croulé, et ont pris l'inclinaison qu'ils ont conservée depuis. la même chose arrivera nécessairement à ce passage de _conaïca_ lorsqu'avec le laps du tems, les effets des pluies, de gelées, des rayons solaires, auront fait tomber en ruine ces parois, quoique de roche rive; car ses agens puissans font sentir leur énergie aux corps les plus durs. ainsi les bords du _chapilancas_ perdront insensiblement la régularité de leur distance, de leurs côtés rentrans et saillans, après l'avoir peut-être conservée plus long tems que d'autres excavations, parce que c'est une pierre dure, qui n'est mêlée d'aucune veine de terre movible. nous pouvons le croire sans hésiter; car ce n'est que le seul frottement de l'eau qui a excavé ce lit jusqu'à la profondeur qu'il a. mais le tems, qui réduit les roches les plus dures en sablon, ira toujours en élargissant la partie inférieure, par son action continuelle et insensible: aussi voit-on ce ruisseau rouler de petites pierres qui se détachent sous les eaux, comme on en apperçoit dans la plaine où il les entraîne, en sortant de la montagne, pour se décharger dans une terrain plus spatieux. «que ce canal ait été excavé à cette profondeur par l'effet continuel du frottement des eaux, ou qu'il a été ouvert par une secousse de tremblement de terre qui fit fendre la montaigne, de sorte que le ruisseau qui couloit d'un autre côté, se soit jetté de celui-ci. il est certain que cette ouverture profonde est postérieure à l'arrangement que les terrains eurent après le déluge; et que c'est ainsi que ces énormes _quebradas_ de la partie méridionale de l'amérique, se sont formées avec le tems, par le frottement du cours rapide des eaux. en effet, on observe que la force avec laquelle s'écoulent toutes les eaux de cette partie du globe, suffit pour arracher des roches d'une masse extraordinaire. c'est pourquoi l'on voit en certaines parages des marques évidentes de leurs excavations profondes au milieu même des lits de ces eaux. ce sont des cubes d'une grandeur énorme, qui n'ont pu être détachés avec la même facilité que les parties contiguës. la rivière _d'iscutbaca_, qui coule près d'une hameau de même nom, nous présente dans son lit une de ces masses, dont la forme est précisément celle d'une cube. lorsque l'eau est basse, ce cube s'élève à sept ou huit _varas_ au-dessus du courant: chaque côté porte douze _varas_ de face. mais ces masses, et autres moindres de différentes formes, qui se voient dans les eaux, ne peuvent être arrivées à cet état, sans que l'eau les ait dégarnies peu-à-peu des pierres, des sables que les envelopoient, et qu'elle a arrachés de tous côtés pour les laisser isolées; or elles se maintiendrons dans cette position, jusqu'à ce que les eaux, cavant de plus en plus, rencontrent enfin à la base des veines de matières friables et dissolubles, qu'elles pénétreront et qu'elles emporteront, en détruisant l'assiette sur laquelle posent ces masses jusqu'alors _inamovibles_. une crue d'eau considérable, et qui ne laissera plus paroître qu'une _varas_ de cette masse, pourra dans ce tems-là l'arracher, et la faire rouler; mais ce mouvement, et les chocs qu'elle éprouvera de la part d'autres masses moins grosses, suffiront pour en briser les parties saillantes, et la réduire en parties moins volumineuses, qui rouleront avec plus de facilité; et qui par cette seul cause diminueront encore. c'est à cette cause qu'on doit attribuer ces quantités prodigieuses de pierres répandues ça et là sur les bords de ces eaux, de même que ces roches enormes qu'on y voit détachées, et que jamais les forces humaines n'auroient pu mettre en mouvement. «mais pour donner une idée quelconque de la profondeur de ces excavations, relativement au terrain ou au sol habitable de la partie haute de l'amérique, il est à propos de rapporter quelques expériences. «guancavelica est une bourgade, ou un corps municipal, situé dans une de ces profondeurs, formées par différentes suites d'éminences. le mercure du baromètre y descend, et s'arrête à dix-huit pouces une ligne et demie. sa plus grande variation y est de - / à - / . sa hauteur est donc de toises, ou - / _varas_ au-dessus du niveau de la _mer_. au haut du mont où se trouve la mine de mercure, mont qui est habitable par-tout, et qui est immédiatement surmonté par d'autres, autant qu'il s'élève au-dessus de guancavelica, le mercure descend et s'arrête à pouces lignes. sa hauteur est donc de - / toises, ou de varas au-dessus du niveau de la mer. ainsi les eaux ont encore fait cet autre excavation comme il est facile de le voir par des indices manifestes. on remarque en effet dans la partie voisine de leur lit, des roches détachées, toutes semblables à celles qui sont au milieu des eaux; ce qui prouve que les eaux ont été au même niveau à une époque beaucoup plus ancienne, et qu'elles ont excavé le sol, a force d'en arracher les parties agrégées. «ces terrains sont couverts par un si grand nombre de courans, qu'il n'en est aucun ou l'on n'en aperçoive, soit dans des ravins, soit entre des montagnes. j'ai observé que la superficie des terrains qui en avoisine les lits, est plus unie aux confluens, où plusieurs de ces courans se réunissent. cela vient de ce que l'éminence, qui se trouve au confluent, paroît avoir été diminuée à la partie où elle a du former une pointe saillante, à mesure que les eaux l'ont rongée de l'un ou de l'autres côté, en continuant leurs excavation. ces surfaces planes sont comme par étages, les unes plus hautes que les autres, et se sont insensiblement formées, selon que l'eau s'est plus ou moins arrêtée à différente hauteur, pendent qu'elle creusoit ces lits. on observe, au contraire, que les bords élevés dans ces courans, n'ont presque point de largeur dans les endroits où l'eau a pu suivre son cours très-directement. c'est cependant sur ces bords étroits et escarpées que se trouvent pratiqués les chemins par où l'on passe. le danger y est très grand: car à peine un animal peut-il poser le pied. toutes les fois que le courant fait un détour, la surface des bords a plus de largeur; cependant moins que lorsque plusieurs se réunissent. un voit facilement pourquoi. l'eau forcée de se détourner, s'éloigne plus de la rive que quand elle va en ligne droite, et ronge ainsi le côté saillant sur lequel elle fait son détour, et qui en devient comme le centre. «on peut conclure de ce que je viens de dire, à quelle élévation est la partie haute ou montagneuse de l'amérique, relativement à la partie basse, et qu'il y a des excavations extrêmement profondes; car elles ont, comme je l'ai déjà dit, - / varas perpendiculaires, ou même d'avantages: cependant elles ont assez de surface pour devenir le local de nombre d'habitations fort peuplées, qui en tirent tous les produits nécessaires à la vie. parmi ces _quebradas_, il en est de plus étendues ou de moins profondes que les autres. or, c'est en ceci que cette partie du monde se distingue de toutes les autres. «mais il est indifférent pour mes vues que ces vastes ouvertures soient l'effet des courans d'eau, ou de toute autre cause. ce que je me propose, est uniquement de montrer qu'elles sont d'autant plus profondes et plus vastes, que ces terrains sont immensément hauts.» m. monnet considers the natural operations of water, upon the surface of the earth, as truly forming the shape of that surface; but he draws some very different conclusions from those which i have formed. it is in his _nouveau voyage minéralogique, fait dans cette partie du hainault connue sou le nom de thiérache._ journal de physique, aoust . «il ne faut pas s'attendre à trouver dans ce pays des hautes montagnes qui frappent la vue de loin; c'est seulement un pays dont l'élévation est générale sur tout ce qui l'entoure, et est coupé profondément par des vallées ou ravin, ouvrage des eaux, qui, la comme ailleurs, ont use et coupé peu-à-peu les terrains et les roches les plus dures, pour s'ouvrir un passage; et peut-être pourroit-on dire; si la diminution des eaux n'étoit pas trop sensible, qu'un jour ce pays offrira des montagnes hautes est escarpées comme tant d'autres, après que les eaux auront creusé, pendant des milliers de siècles, ses gorges, ses ravins, et diminué la largeur des masses de terrain qui sont entr'eux. «quant à present, on ne peut y voir que de petites montagnes, ou plutôt des bosses de terre, avec des platures plus ou moins considérables à leurs sommets, avec de côtés coupées plus ou moins obliquement, ou plus ou moins droites. ce qu'on y trouve de singulier c'est que ces petites montagnes sont presque toutes plus basses que les plaines qui les avoisinent, encore ne sont elles que dans la partie calcaire. «la plus profonde tranchée de ce pays est, sans contredit, celle ou coule la meuse, qui, malgré la dureté des roches d'ardoise et de quartz au travers desquelles elle passe, a coupé le terrain depuis charleville jusqu'â givet, à une très-grande profondeur. dans cette distance, on voit presque par-tout les côtés coupées presque à pic sur la rivière, de deux à trois cents pieds de hauteur perpendiculaire; et comme c'est une règle générale, que plus les côtés sont coupées droites, moins elles sont distantes l'une de l'autre, on conçoit que le canal de la meuse, dans cette étendue de terrain, doit être fort étroit, eut égard à beaucoup d'autres où il coule un bien moindre volume d'eau. cela n'empêche pas qu'on n'y aperçoive des marques de la règle général que fait l'eau, et n'y ait taillé des angles saillans et des angles rentrans, qui sont très-grands en certains endroits. nous verrons que revin et fumai, deux lieux principaux des bords de la meuse, sont situés sur deux de plus grandes de ces ouvertures où se trouvent des platures assez vaste pour permettre, outre un emplacement considérable pour les maisons, l'établissement de beaucoup de jardins, et même des pièces à grain et des prairies. aussi, quand on arrive sur la tranchée de la meuse, les lieux et les terrains cultivés qu'on voit dans son fond, paroissent comme séparés sous les autres et comme dans un autre pays. «les autres coupures ou ravins de ce pays, quoique moins profonds, offrent cependant cette singularité, remarquée déjà ailleurs, que leurs grandeurs et profondeur ne sont point du tout proportionnées au volume de l'eau qui y coule. «le massif sur lequel est situé beaumont, est coupé presque perpendiculairement à l'ouest, sud-ouest et cette coupe en fait de ce côté-là un rempart inaccessibles, ayant plus de pieds de hauteur. quand j'ai considéré cette grande coupe, et le détour que fait la petite rivière qui coule au bas de ce massif, je n'ai pus me refuser à croire qu'il n'y avoit en là un bien plus grande courant d'eau, qui a battu et miné ce massif, en s'y brisant avec force; car on ne peut supposer, avec quelque vraisemblance, que cet ouvrage ait été fait par le volume d'eau qui y coule actuellement: et il ne faut pas s'étonner de ce disparate; par-tout vous le trouverez; ce qui démontre évidemment que la quantité d'eau diminue insensiblement, et que la partie solide de notre globe augmente à proportion que la partie liquide diminue; et s'il faut encore étendre ce principe, j'ajouterai, que par-tout vous verrez les bornes de la mer et des rivières reculées; par-tout vous trouverez d'anciens courans d'eau desséchés, et même des rivières considérables, à en juger par les collines ondulées qu'on voit encore. mais cette partie essentielle de la minéralogie qui est effrayante par les conséquences qu'elle presente, et qui peut influer sur le système général du monde, sera étendue un jour dans un autre memoire, où je décrirai d'anciens cours de rivières de la france, qui n'existent plus. j'espère fair voir alors, appuyé par les faits que me fournira l'histoire, que les rivières et les fleuves actuels ont été plus volumineux qu'ils ne le sont maintenant, et qu'il existoit en france un grande nombre de vastes lacs, comme dans l'amérique septentrionale, et dont à peine il nous reste des traces aujourd-hui.» this opinion of m. monnet, concerning the diminution of water upon the earth, does not follow necessarily from those appearances which he has mentioned. the surface of the earth is certainly changed by the gradual operations of the running water, and it may not be unfrequent, perhaps, to find a small stream of water in places where a greater stream had formerly run; this will naturally happen upon many occasions, as well as the opposite, by the changes which are produced upon the form of the surface. likewise the conversion of lakes into plains is a natural operation of the globe, or a consequence of the degradation of the elevated surface of the earth, without there being any reason to suppose that the general quantity of running water upon the land diminishes, or that the boundaries of the various seas are suffering any permanent removal. whether we examine the alps in the old world, or the andes in the new, we always find the evidence of this proposition, that the exposed parts of the solid earth are decaying and degraded; that these materials are hauled from the heights to be travelled by the waters over the surface of the earth; and that the surface of the earth is perpetually changing, in having materials moved from one place and deposited in another. but these changes follow rules, which we may investigate; and, by reasoning according to those rules or general laws, upon the present state of things, we may see the operation of those active principles or physical causes in very remote periods of this mundane system, and foresee future changes in the endless progress of time, by which there is, for every particular part, a succession of decay and renovation. chap. xiii. _the same subject continued._ the chevalier de dolomieu, in his most indefatigable search after natural history and volcanic productions, has given us the description of some observations which are much calculated to put this subject in a conspicuous point of view. i give them here as examples of the operation of water wasting the land and forming valleys in a system where every thing is tending to the wisest end or purpose; but they are no less interesting as proper to give us a view of the mineral operations of the globe. that therefore which, according to the order of the subject, ought to be cited in another part of this work, is here necessarily mixed in the narrative of this natural historian. there is, upon this occasion, such a connection of the facts by which the mineral operations of the earth, either consolidating the materials deposited at the bottom of the sea, or elevating land by the power of subterraneous heat, are to be understood, and of those by which the operations of the surface are to be explained, that while they cannot be separated in this narration, they throw mutual light upon each other. it is in his mémoire sur les volcans éteints du val di noto en sicile. journal de physique, septembre . «je trouvai les premiers indices de ces volcans, en allant de syracuse à sortino, à une lieue de cette ville, au fond du profond vallon qui y conduit. quelques morceaux de laves entraînés et arrondis par les eaux m'annoncèrent d'avance que j'allois entrer dans un pay volcanique. mon attention se fixa bientôt après sur un courant de laves que je vis sortir d'une montagne calcaire qui étoit sur ma droite, il étois coupé par une vallon dont les eaux couloient sur un sol calcaire, et alloit se perdre dans le massif également calcaire qui étoit sur ma gauche. je passai en suite alternativement sur des matières calcaires et volcaniques, pour arriver à sortino, ville baronale bâtie sur une montagne calcaire qui domine la vallon, et qui lui presente des escarpemens de plus de toises d'élévation, dans lesquels les banc de pierres dure sont horizontaux, et exactement parallèles.» here, it is to be observed, are horizontal beds remaining, which give a measure of what had been abstracted by some cause, which is our present subject of investigation. the chevalier proceeds: «les environs de sortino m'offrirent des phénomènes et des singularités dont l'explication me parut difficile, et qui tinrent pendant longtemps mon esprit en suspens. je vis d'abord les matières volcaniques ensevelies sous des bancs horizontaux de pierres calcaires, très-coquillières, contenant sur-tout une infinité de madréporites, quelques-uns d'un volume énorme. je vis ensuite des hauteurs dont les sommets seuls étoient volcaniques, et les noyaux calcaires, sans que les laves qui couronnoient ces sommets eussent communication avec aucun courant, et eussent d'autre étendue que le plateau qu'elles recouvroient. ces laves n'avoient pu être formées où je les voyois; elles étoient venues d'ailleurs; mais d'où et comment? etc. je me déterminai à consulter les montagnes les plus hautes, qui étoient à quelque distance. j'en vis de loin plusieurs dont la forme étoit à peu-près conique, et dont les sommets étoient pointus; elles étoient vers le nord, ou nord-ouest de sortino, dans la direction de l'etna, qui terminoit mon horizon, à une distance de ou lieues, etc. «la montagne saint-george, une des plus hautes de tout le canton du sommet de laquelle je pouvois prendre une idée topographique de tous le pays, qui domine tout ce qui entoure, à l'exception de quelques pics calcaires qui lui sont au sud; (tel que celui de la montagne de boujuan); cette montagne, dis-je, dont la forme est conique, et qui est isolée par des vallées, dont le sol lui étoit sur-abaissé de ou toises, a sa base calcaire. sur cette première assise repose une couche volcanique, ensuite une autre tranche volcanique calcaire, à laquelle succède un sommet formé d'une lave dure. une autre montagne auprès du fief de la copodia, également conique, est toute volcanique, à l'exception d'une couche de pierre calcaire dure et blanche, qui la tranche à moitié hauteur parallèlement à sa base. quelques montagnes où les couches volcaniques ou calcaires sont plus ou moins nombreuses. la montagne de pimalia est volcanique à sa base et calcaire à son sommet; et enfin la montagne isolée sur laquelle est bâtie la ville de carientini est moitié calcaire et moitié volcanique: mais ici la division des deux substances se fait par un plan verticale, etc. après être arrivé à cette limite des volcans, dont je poursuivois le foyer, je pris du côté de l'est; je suivis jusqu'à melilli les hauteurs qui accompagnent la vallée de lentini, et qui dominent la plaine d'auguste; et cheminant à mi côté je vis déboucher du milieu des montagnes calcaires, qui, réunies par leur base, ne forme qu'une même groupe, sous le nom de monts hybleens, _colles hyblei_, plusieurs courans de lave qui se terminent comme s'ils avoient été coupés sans avoir eu le temps de descendre dans la vallée, et de s'incliner pour en prendre la pente. plusieurs de ces courans sont cristallisés en basaltes prismatiques; on en voit de très-belles colonnes au-près de melilli. au delà de cette ville jusqu'à syracuse, on ne voit plus de traces de volcans, et les escarpemens en face du golfe d'auguste n'offrent qu'un massif calcaire en bancs horizontaux, etc. «je revins a sortino, et en allant visiter l'emplacement de l'ancienne erbessus, connue maintenant sous le nom de pentarica, je traversai deux gorges d'une extrême profondeur, dont les encaissemens, taillés presque à pic, ont plus de pieds d'élévation, etc.» the chevalier then found, in the mountain of santa venere, an extinct volcano; and proceeds in his memoir to give some explanation for those appearances, as follows: «je ne pus pas douter que cette montagne ne fût le volcan que je cherchois, et qui avoit répandus ses laves à une très-grande distance autour de lui, sur-tout dans la partie de l'est; mais il me restoit à résoudre le problème de la formation des montagnes isolées et coniques, mi-parties volcaniques et calcaires, qui ne tiennent à aucune courant, et qui sembloient n'avoir aucune relation directe avec mon volcan. l'étude de la montagne santa-venere, et des pays circonvoisins, m'apprit que ce volcan s'étoit élevé au milieu de la mer qui alors occupoit nos continens, que sa tête seule s'étoit soulevée au-dessus du niveau des eaux. je fus convaincu que, lorsqu'il répandoit autour de lui des torrens de matières enflammées, la mer entassoit des dépôts calcaires; que chaque nouvelle éruption trouvoit un sol plus élevé, sur lequel elle se répandoit; que bientôt les nouvelles matières volcaniques étoient ensevelies sous de nouveaux dépôts, et qu'ainsi, par l'entassement successif et régulier des produit du feu et des dépôts de l'eau, s'étoit formé un énorme massif, á sommet aplati et horizontal. ce massif occupoit tout le centre du val di noto, recouvroit de plusieurs centaines de toises le sol sur lequel s'étoit répandu les premières laves, et fut divisé, morcelé et dégradé par les courans ou par le ballottement des eaux, lors de la grande débâcle du de la catastrophe qui changea l'emplacement des mers. les vallons et les gorges qui se formèrent au milieu de ce massis, séparèrent les laves de la montagne à qui elles appartenoient, coupèrent les courans, et façonnèrent, avec les débris de ce massif des montagnes de toutes les formes, mais la majeure partie conique, ainsi qu'on peut le voir journellement, lorsque, dans un terrain argilleux et submergé l'eau, se retirant avec précipitation, excave par-tout où elles trouve moins de resistance, creuse les premiers sillons qu'elle a tracés et forme des petits cônes, dont les sommets sont à la hauteur du sol sur lequel reposoient les eaux. les parties où les laves avoient coulé successivement dans la même direction, les unes au-dessus des autres, ont donné naissance aux montagnes dans lesquelles les couches volcaniques et calcaires se succèdent parallèlement. celles sur lesquelles aucunes laves ne se sont portées, n'ont produit que des montagnes totalement calcaires que se trouvent entremêlées avec les autres. celles enfin sur lesquelles le hazard ou des circonstances locales out entasse de préférence, et dans le même lieu, les matières que vomissoit le volcan, sans laisser le temps au dépôt des eaux de se mêler avec elles, ont produit quelques petites montagnes presque entièrement volcanique, où les cendres sont agglutinées par une pâte calcaire, etc. cette théorie rend raison de tous le phénomènes et de toutes les singularités qui s'observent dans le mélange des produits du feu et des dépôts de l'eau, et une infinité de preuves de differens genres, mais qui seroient étrangères à ce memoire, concourent à démontrer, l'existence d'un ancien plateau qui étoit élevé de plusieurs centaines de toises au-dessus du sol actuel des vallées et du niveau de la mer, qui couvroit non seulement le val _di noto_, mais encore toute la sicile, et dont les débris ont formé toutes les montagnes actuellement existantes, à l'exception de l'etna.» it is not the explanation here given by the chevalier de dolomieu, of the manner in which this great mass of land was formed in the sea, that is concerned with the subject at present under our examination, but certain facts set forth in the memoir, and a certain conclusion which is there endeavoured to be drawn from those interesting facts[ ]. this will be understood by considering; first, it is on all hands acknowledged, that the stratified matter of the globe was successively deposited in the bottom of the sea; secondly, it is also agreed, that this great mass of sicily, formed originally under the sea, was afterwards placed in the atmosphere, whether by the retreat of the sea or by the elevation of the land; and now, lastly, we are of one mind with respect to the present shape of things, as having been produced by the wasting away of great part of that mass which had been once continued all over the island, as high at least as the tops of the mountains, _i.e._ about a mile above the level of the sea; we only differ in the time and agents which have been employed in this operation. [footnote : in the first part of this work, the distinction has been made of true volcanic productions, and those which are so frequently confounded with them; these last, though the creatures of subterranean fire, and bodies which have been made to flow in a fluid state, are clearly different from those masses of lava which have issued from a volcano, as has been there described. i would only here observe, that, according to this theory, these bodies, which the chevalier de dolomieu here represented as lava and volcanic production, must be considered as unerupted lavas, which had been made to flow among the strata of the earth, where other at the bottom of the sea, or during those operations by which this land was erected above the level of the ocean.] on the one hand, the memoir now before us represents this great effect as belonging to an unknown cause, so far as we are ignorant of that grand _débacle_ or _catastrophe_ which changed the situation of the sea. on the other hand, the theory now proposed explains this operation, of forming those conical mountains of sicily, and hollowing out its valleys, by known causes, and by employing powers the most necessary, the most constant, and the most general, that act upon the surface of the earth. but, besides explaining this change of land and water by an unknown cause, our author has here employed, for the removing of this mass of solid rock, powers which appear to me no ways adequate to the end proposed. the running of water upon the soft mud left by a river, given here as an example, corresponds indeed in some respects with the form of valleys; for, water acts upon the same principle, whether it makes a channel through the subtile sediment of a river, or through the travelled materials of a valley. but it is not here that there is any difficulty in conceiving the rivers of sicily to have shaped the mountains and the valleys; it is in removing the masses of solid rock, which covered the whole surface of this land in successive strata, that any doubt could occur in ascribing the actual appearances of things to the natural operations of the earth; but it is here particularly that the retreat of the sea, in whatever manner supposed to be done, is altogether incompetent for the purpose which is now considered. i flatter myself, that when the chevalier de dolomieu, who has employed his uncommon talents in examining and elucidating the effects of fire in the bowels of those burning mountains, shall consider and examine the effects of time upon the surface of the earth, he will be ready to adopt my opinion, that there is no occasion to have recourse to any unknown cause, in explaining appearances which are every where to be found, although not always attended with such remarkable circumstances as those with which his labours have enriched natural history. it may be proper to give a view of the operations of nature upon the apennines. it is from an account of a journey into the province of abruzzo, by sir william hamilton. phil. trans. . the road follows the windings of the garigliano, which is here a beautiful clear trout stream, with a great variety of cascades and water-falls, particularly a double one at isola, near which place cicero had a villa; and there are still some remains of it, though converted into a chapel. the valley is extensive, and rich with fruit trees, corn, vines, and olives. large tracts of land are here and there covered with woods of oak and chestnut, all timber trees of the largest size. the mountains nearest the valley rise gently, and are adorned with either modern castles towns, and villages, or the ruins of ancient ones. the next range of mountains, rising behind these, are covered with pines, larches, and such trees and shrubs as usually abound in a like situation; and above them a third range of mountains and rocks, being the most elevated part of the apennine, rise much higher, and, being covered with eternal snow, make a beautiful contrast with the rich valley above mentioned; and the snow is at so great a distance as not to give that uncomfortable chill to the air which i have always found in the narrow valleys of the alps and the tyrol. having thus examined the alpine countries both of the old world and the new, it remains to observe some river in a more low or level country emptying itself into a sea that does not communicate with the ocean. the wolga will now serve for this purpose; and we shall take our facts from the observations of those men of science who were employed by their enlightened sovereign to give the natural as well as the economical history of her dominions. russia may be considered as a square plain, containing about degrees of longitude, and of latitude, that is, between the ° and ° degrees. the east side is bounded by the oural mountains, running in a straight line from north to south. the west is bounded by poland. the south reaches to the caspian and black seas, as does the north to the polar ocean. the greatest part of the water which falls upon this extensive country is delivered into the caspian by the river wolga; and this water runs from the east and west sides, gathered in two great rivers, the kama and the oka. the water thus gathered from the two opposite extremities of this great kingdom meet in the middle with the wolga, which receives its water from the north side. we thus find the water of this great plain running in all directions to its centre. had this been the lowest place, here would have been formed a sea or lake. but this water found a lower place in the bed of the caspian; and into this bason it has made its way, in forming to itself a channel in the great plain of the wolga. our present purpose is to show that this channel, which the wolga has cut for itself, had been once a continued mass of solid rock and horizontal strata, which in the course of time has been hollowed out to form a channel for those waters. these waters have been traversing all that plain, and have left protuberances as so many testimonies of what had before existed; for, we here find the horizontal strata cut down and worn away by the rivers. m. pallas gives us very good reason to believe that the caspian sea had formerly occupied a much greater extent than at present; there are the marks of its ancient banks; and the shells peculiar to the caspian sea are found in the soil of that part of its ancient bottom which it has now deserted, and which forms the low saline _steppe_. he also makes it extremely probable that the caspian then communicated with the euxine or black sea, and that the breaking through of the channel from the euxine into the mediterranean had occasioned the disjunction of those seas which had been before united, as the surface of the caspian is lowered by the great evaporation from that sea surrounded with dry deserts. however that may he, it is plain, that throughout all this great flat inland country of russia, the solid rocks are decaying and wearing away by the operation of water, as certainly, though perhaps not so rapidly, as in the more mountainous regions of the earth. if there is so much of the solid parts worn and washed away upon the surface of this earth, as represented in our theory; and if the rivers have run so long in their present courses, it may perhaps be demanded, why are not all the lakes filled up with soil; and why have not the black and caspian seas become land or marshy ground, with rivers passing through them to the ocean? here is a question that may be considered either as being general to all the lakes upon the earth, or as particular to every lake which should thus find a proper explanation in the theory. with regard to the last of these, the question has already been considered in this view, when the particular case of the rhône was taken as an example; and now we are only to consider the question as general to the globe, or so far as belonging to the theory, without particularising any one case. it must be evident, that the objection to the theory, here supposed to be made, is founded necessarily upon this, that the solid basis of our continent, on whose surface are found the lakes in question, is preserved without change, because, otherwise, the smallest variation in the basis may produce the most sensible effects upon the surface; and in this manner might be produced dry land where there had been a lake, or a lake where none had been before. but, as the present theory is founded upon no such principle of stability in the basis of our land, no objection, to the wasting operations of the surface of the earth, can be formed against our theory, from the consideration of those lakes, when the immediate cause of them should not appear. the natural tendency of the operations of water upon the surface of this earth is to form a system of rivers every where, and to fill up occasional lakes. the system of rivers is executed by wearing and wasting away the surface of the earth; and this, it must be allowed, is perfect or complete, at least so far as consistent with another system, which would also appear to be in nature. this is a system of lakes with which the rivers are properly connected. now, as there are more way than one by which a lake may be formed, consistent with the theory, the particular explanation of every lake must be left to the natural history of the place, so far as this shall be found sufficient for the purpose. there are many places which give certain appearances, from which it is concluded, by most intelligent observators, that there had formerly existed great lakes of fresh water, which had been drained by the discharge of those waters through conduits formed by some natural operation; and those naturalists seem to be disposed to attribute to some great convulsion, rather than to the slow operation of a rivulet, those changes which may be observed upon the surface of the earth. let us now examine some of those appearances, in order to connect them with that general system of moving water which we have been representing as every where modifying the surface of the earth on which we dwell. it is the p. chrysologue de gy, who gives the following description. journal de physique, avril . «la principaute de porrentrui l'emporte encore en ce genre sur le reste du jura à ce qu'il paroît. on pourra en juger sur les circonstances locales que je vais rapporter. une partie de cette principauté est divisée en quatre grandes vallées, d'environs quatre lieues de long, sur trois quarts-d'heure ou une heure de large, séparées par autant de chaînes de montagnes fort élevés et large en quelques endroits d'une lieue et demie. les extrémités de chacune de ces vallées sont plus élevées que le milieu, et on ne peut pas en sortir par ces extrémités sans beaucoup monter. mais ces vallées ont des communications entr'elles par une pente assez douce à travers ces masses énormes de montagnes qui les separent, et qui sont coupées au niveau du milieu des vallées sur , , toises de hauteur et dans toute leur largeur. on pourroit assez justement comparer ces vallées à des berceaux posés les uns à côté des autres, dont les extrémités, remplies en talus, seroient plus élevés que les cotés, et dont ces côtés seroient coupés jusqu'au fond, pour laisser une passage de l'un à l'autre. je connois sept à huit passages semblables à travers ces hautes montagnes, dans une quarré d'environ quatre à cinq lieues; et dont quatre aboutissent à la vallée de mouthier-grand-val. ces passages sont évasés dans le dessus, d'environ une demi-lieue par endroits; mais leurs parois, en talus, se rejoignent dans le fond où coule un ruisseau. on a pratiqué des routes sur quelques-uns de ces talus, mais les roches sont quelquefois si resserrées et si escarpées, qu'on a été obligé de construire un canal sur le ruisseau, pour y faire passer la route. c'est-là que l'on voit à son aise, la nature de ces rochers primitives, leur direction, leur inclinaison, et tous leurs autres accidens qui demanderaient chacun une dissertation particulière trop longue pour le moment, et il faut les avoir vues pour se faire une juste idée des sentimens de grandeur, de surprise, et d'admiration qu'elles inspirent, et que l'on ne peut pas exprimer par des paroles. cependant, les sources de ruisseaux, ou si l'on veut des rivières qui traversent ces montagnes, sont beaucoup plus basses que les sommités des montagnes elles-mêmes, ces sources ne font donc pas la cause de ces effets merveilleux. il a fallu un agent plus puissant pour creuser ces abîmes.» m. de la metherie has taken a very enlightened view of the country of france; and has given us a plan of the different ridges of mountains that may be traced in that kingdom, (journal de physique, janvier ). now there is a double purpose in natural history to which such a plan as this may be applied; viz. first, to trace the nature of the solid parts, on which the soil for vegetation rests; and, secondly, to trace the nature of the soil or cultivated surface of the earth, on which depends the growth of plants. with regard to the first, we may see here the granite raising up the strata, and bringing them to the light, where they appear on each side of those centrical ridges. what m. de la metherie calls _monts secondaires_, i would call the proper strata of the globe, whether primary or secondary; and the _monts granit_, i would consider as mineral masses, which truly, or in a certain sense, are secondary, as having been made to invade, in a fluid state, the strata from below, when they were under water; and which masses had served to raise the country above the level of the ocean. but this is not the subject here immediately under consideration; we are now tracing the operations of rivers upon the surface of the earth, in order to see in the present state of things a former state, and to explain the apparent irregularity of the surface and confusion of the various mineral bodies, by finding order in the works of nature; or a general system of the globe, in which the preservation of the habitable world is consulted. for this last purpose also the mineral map of m. de la metherie is valuable. it gives us a plan of the valleys of the great rivers, and their various branches, which, however infinitely ramified, may be considered as forming each one great valley watered, or rather drained, by its proper river. but the view i would now wish to take of those valleys, is that of habitable and fertile countries formed by the attrition of those rivers; and to perceive the operation of water wearing down the softer and less solid parts, while the more hard and solid rocks of the ridges, as well as scattered mountains, had resisted and preserved a higher station. in this map, for example, let us suppose the first and second ridge of our author's plan to be joined at the mouth of the loire, and retain the water of that river, as high as the summit of its surrounding ridges; this great valley of the loire, which at present is so fine and fertile a country, would become a lake; in like manner as the proper valley of the rhône, above st maurice, would be drowned by shutting up that gap of the mountains through which the rhône passes in order to enter the plain of geneva. this is the view that p. chrysologue takes of those small valleys formed between the ridges of the jura. but this is not perhaps the just view of the subject; for though by closing the gap by which the loire or rhône, passes through the inclosing ridge, the present country above would certainly be overflowed by the accumulated waters, yet it is more natural to suppose, that the great gap of the loire, or the rhône, had been formed gradually, in proportion as the inclosed country had been worn down and transported to the sea. we have but to consider, that the attrition of those transported materials must have been as necessary for the hollowing out of those gaps in the solid rock of the obstructing mountains, as the opening of those gaps may have been for the transporting of those materials to the sea. but it is perhaps impossible, from the present appearance of things, to see what revolutions may have happened to this country in the course of its degradation; what lakes may have been formed; what mountains of softer materials may have been levelled; and what basons of water filled up and obliterated. this general view of the valley of the loire, and all its branches, is perhaps too extensive to be admitted in this reasoning from effect to cause; we must approximate it by an intermediate step, which will easily be acknowledged as entering within the rule. it is in forrez, near the head of the loire. there we find the plain of mont brison, , toises or miles long and half as wide, surrounded by a ridge of granite mountains on every side. here the river, which is a small branch of the loire, enters at the upper end of the plain (as m. de bournon has described)[ ] «par une gorge très étroite et tortueuse,» and goes out in like manner at the under end. [footnote : journal de physique, mai .] those french philosophers, who have seen this plain, have little doubts of this having been a lake, that is to say, they easily admit of the original continuity of those ridges of mountains in which the gaps are now found, through which the river passes. but upon those principles it must be evident, that the river has hollowed out that plain, at the same time that it had formed the gaps in those ridges of the granite mountains. the only solid part, or original stratum, which m. de bournon has described as having seen in this plain, is a decomposing _grès_ or sandstone; but there is reason to suppose, that there had been both calcareous and argillaceous or marly strata filling the hollow of that space which is inclosed by the granite mountains; consequently, no difficulty in conceiving that the river, which must wear away a passage through those mountains, should also hollow out the softer materials within, and thus form the plain, or rather a succession of plains, in proportion as the level of the water had been lowered with the wearing mountains. if we are allowed to make this step, which i think can hardly be refused, we may proceed to enlarge our view, by comprehending, first, the vallais of the rhône, secondly, the countries of the seine and rhône, above the mountains through which those two rivers in conjunction have broke, below lyons; and, lastly, that country of the rhône and durance which is almost inclosed by the surrounding mountains, meeting at the mouth of the rhône. but this reasoning will equally apply to the countries of the garonne, the loire, and the seine. one observation more may now be made with regard to the courses of great rivers, and the fertile countries which they form in depositing the travelled soil; it is this. that though those rivers have hollowed out their beds and raised their banks; though they are constantly operating in forming fertile soil in one place and destroying it in another; and though, in many particular situations, the fertile countries, formed at the mouths of those rivers, are visibly upon the increase, yet the general progress of those operations is so slow, that human history does not serve to give us information almost of any former state of things. the nile will serve as an example of this fact. the river nile, which rises in the heights of ethiopia, runs an amazing tract through desert countries, and discharges its waters near the bottom of the mediterranean sea, fertilizes a long valley among barren countries with which it is surrounded, and thus lays the foundation of a kingdom, which, from its situation and the number of people it can maintain and easily bring together for any manner of action, is perhaps the strongest that can well be imagined. accordingly, it has been of old a great kingdom, that is to say, a powerful state within itself; and has left monuments of this power, which have long been the admiration of the world. the most ancient grecian histories mention these monuments as being no better known, with regard to their dates and authors, than they are at this day. the conclusion here meant to be drawn is this, that, in a period of time much more ancient than the most ancient periods in human history, egypt had been a country formed and watered by the nile in like manner as it is at present; that though continual changes are making in this as well as in every other river, yet, on the whole, no sensible alteration can be discerned within the compass of human experience, consequently, it is only by considering, in a scientific manner, the nature of things, and making allowances for operations which have taken place in time past, that any competent judgment can be formed of the present shape and condition of countries, or of any particular place upon the surface of this earth, so far as regards its date, its causes, or its future state. nothing, almost, but the kingdom of egypt would have formed those stupendous monuments of art and labour; and nothing but the present state of egypt, fertilised by the nile, could have formed that powerful kingdom which might execute those works. thus there is a system of mountains and valleys, of hills and plains, of rivulets and rivers, all of which are so perfectly connected, and so admirably proportioned, in their forms and quantities, like the arteries and veins of the animal body, that it would be absurd to suppose any thing but wisdom could have designed this system of the earth, in delivering water to run from the higher ground; or that any thing could have formed this beautiful disposition of things but the operation of the most steady causes; operations which, in the unlimited succession of time, has brought to our view scenes which seem to us to have been always, or to have been in the original construction of this earth. to suppose the currents of the ocean to have formed that system of hill and dale, of branching rivers and rivulets, divided almost _ad infinitum_, which assemble together the water poured at large upon the surface of the earth, in order to nourish a great diversity of animals calculated for that moving element, and which carry back to the sea the superfluity of water, would be to suppose a systematic order in the currents of the ocean, an order which, with as much reason, we might look for, in the wind. the diversity of heights upon the surface of the earth, and of hardness and solidity in the masses of which the land is formed, is doubtless governed by causes proper to the mineral kingdom, and independent either of the atmosphere or sea; but the form and structure by which the surface of the earth is fitted peculiarly to the purpose of this living world, in giving a fertility which sustains both plants and animals, is only caused by those powers which work upon the surface of the earth,--those powers, the operation of which men in general see with indifference every day, sometimes with horror or apprehension. the system of sustaining plants and animals upon a surface where fertility abounds, and where even the desert has its proper use, is to be perceived from the summit of the mountain to the shore within the region of the sea; and although we have principally taken the alps, or alpine situations, for particular examples, in illustrating this operation of the waters upon the surface of the earth, it is because the effects are here more obvious to every inquirer, and not because there is here to be acknowledged any other principle than that which is to be found on all the surface of the earth, a principle of generation in one sense, and of destruction in another. we may also find in this particular, a certain degree of confirmation to another part of the same theory; a part which does not come so immediately within our view, and concerning which so many contradictory hypotheses have been formed. naturalists have supposed a certain original construction of mountains, which constitution of things, however, they never have explained; they have also distinguished those which have evidently been formed in another manner, that is to say, those the materials of which had been collected in the ocean. now, here are two things perfectly different; on the one hand original mountains formed by nature, but we know not how, endued with solidity, but not differing in this respect from those of a posterior formation; on the other hand, secondary mountains, formed by the collection of materials in the sea, therefore, not having solidity as a quality inherent in their constitution, but only occasional or accidental in their nature. if, therefore, it be the natural constitution of things upon the surface of this earth to indurate and become solid, however originally formed loose and incoherent, we should thus find an explanation of the consolidation of those masses which had been lately formed of the loose materials of the ocean; if, on the contrary, we find those pretended primitive mountains, those bodies which are endued with hardness and solidity, wasting by the hand of time, and thus wearing in the operations natural to the surface of the earth, where shall we find the consolidating operations, those by which beds of shells have been transformed into perfect marble, and siliceous bodies into solid flint? or how reconcile those opposite intentions in the same cause? nothing can be more absurd than to suppose a collection of shells and corals, amassed about the primitive mountains of the earth, to become mountains equally solid with the others, upon the removal of the sea; it would be inconsistent with every principle of sound reasoning to suppose those masses of loose materials to oppose equal resistance to the wasting and destroying operations of the surface of the earth, as do those pretended primitive masses, which might be supposed endued with natural hardness and solidity; yet, consult the matter of fact, and it does not appear that there is any difference to be perceived. there are lofty mountains to be found both of the one kind and the other; both those different masses yield to the wasting operations of the surface; and they are both carried away with the descending waters of the earth. it is not here meant to affirm, that a mass of marble, which is a calcareous substance, opposes equal resistance, whether to the operations of dissolution or attrition, as a mass composed of granite or of quartz; it is only here maintained that there are in the alps lofty mountains of marble, as there are in other places lower masses of granite and its accompanying schistus. but that which is particularly to be attended to here is this: in all countries of the earth, whether of primitive masses or those of secondary formation, whether uniform and homogeneous, or compound and mixed of those two different kinds of bodies, the system is always the same, of hills and valleys, lakes and rivers, ravines and streams: no man can say, by looking into the most perfect map, what is primary or what secondary in the constitution of the globe. it is the same system of larger rivers branching into lesser and lesser in a continued series, of smaller rivers in like manner branching into rivulets, and of rivulets terminating at last into springs or temporary streams. the principle is universal; and, having learned the natural history of one river, we know the constitution of every other upon the face of the earth. thus all the surface of this earth is formed according to a regular system of heights and hollows, hills and valleys, rivulets and rivers, and these rivers return the waters of the atmosphere into the general mass, in like manner as the blood, returning to the heart, is conducted in the veins. but as the solid land, formed at the bottom of the sea or in the bowels of the earth, could not be there constructed according to that system of things which we find so widely pursued upon the surface of the globe, it must be by wasting the solid parts of the land that this system of the surface has been formed, in like manner as it is by the operations of the sea that the shape of the land is determined, upon the shore. thus it has been shown, that the general tendency of the operations natural to the surface of the globe is to wear the surface of the earth, and waste the land; consequently that, however long the continents of this earth may be supposed to last, they are on the whole in a constant state of diminution and decay; and, in the progress of time, will naturally disappear. hence confirmation is added to that mineral system of the earth, by which the present land is supposed to have acquired solidity and hardness; and according to which future land is supposed to be preparing from the materials of the sea and former continents; which land will be brought to light in time, to supply the place of that which necessarily wastes, in serving plants and animals. but what is here more particularly to the purpose is this; that we find an explanation of that various shape and conformation which is to be observed upon the surface of this earth, as being the effect of causes which are constant and unremitting in their operation, which are widely adapted to the end or absolutely necessary in the system of this world, and which, in the indefinite course of time, become unlimited in their effect, or powerful in any conceivable degree. it is not sufficient for establishing the present theory, to refute that most unscientific hypothesis, adopted by some eminent philosophers, of mountains and valleys being the effect of currents in the ocean; it is necessary to see what is their proper cause, and to show that by no other cause known could the general effect, which is of such importance in the system of this world, be actually produced. it is for this reason that we have endeavoured to show that there is a general, an universal system of river and valley, which renders the surface of this earth a sort of organized body destined to a purpose which it perfectly fulfils. but to see the full force of this argument, taken from that order of things which is perceived in that system of valley and river all over the earth, let us examine, first, what would be the effect, in the constitution of this world, of bodies of land formed upon no such system; and, secondly, what would be the effect of the natural constitution of this world and meteorological operations of the atmosphere, if continued for a sufficient length of time, upon a mass of land without any systematic form. for this purpose we shall take for example a portion of this earth, which is the best known to us, that is the south-western part of europe, in order to compare its present state, which so perfectly fulfils the purpose of this world, with that in which no order of valley and of rivers should be fund. let us begin at the summit, which is the mont-blanc. at present the water, falling from the heavens upon this continent, is gathered into a system of rivers which run through valleys, and is delivered at last into the adriatic, the mediterranean, the atlantic, and the german seas; all the rest of this continent, except some lakes and marshes, is dry land, properly calculated, for the sustenance of a variety of plants and animals, and so fulfils the purpose of a habitable earth. now, destroy that system of river and valley, and the whole would become a mixture of lakes and marshes, except the summits of a few barren rocks and mountains. no regular channels for conveying the super-abundant water being made, every thing must be deluged, and nothing but a system of aquatic plants and animals appear. a continent of this sort is not found upon the globe; and such a constitution of things, in general, would not answer the purpose of the habitable world which we possess. it is therefore necessary to modify the surface of such a continent of land, as had been formed in the sea, and produced, by whatever means, into the atmosphere for the purpose of maintaining that variety of plants and animals which we behold; and now we are to examine how far the proper means for that modification is to be found necessarily in the constitution of this world. if we consider our continent as composed of such materials as may decay by the influence of the atmosphere, and be moved by water descending from the higher to the lower ground, as is actually the case with the land of our globe, then the water would gradually form channels in which it would run from place to place; and those channels, continually uniting as they proceed to the sea or shore, would form a system of rivers and their branchings. but this system of moving water must gradually produce valleys, by carrying away stones and earthy matter in their floods; and those valleys would be changing according to the softness, and hardness, destructability or indestructability of the solid parts below. still however the system of valley and river would be preserved; and to this would be added the system of mountains, and valleys, of hills and plains, to the formation of which the unequal wearing down of the solids must in a great measure contribute. here therefore it is evident, _first_, that the great system upon the surface of this earth, is that of valleys and rivers; _secondly_, that no such system could arise from the operations of the sea when covering the nascent land; _thirdly_, that this system is accomplished by the same means which, are employed for procuring soil from the decaying rocks and strata; and, _lastly_, that however this system shall be interrupted and occasionally destroyed, it would necessarily be again formed in time, while the earth continued above the level of the sea. whatever changes take place from the operation of internal causes, the habitable earth, in general, is always preserved with the vigour of youth, and the perfection of the most mature age. we cannot see man cultivate the field, without perceiving that system of dry land provided by nature in forming valleys and rivers; we cannot study the rocks and solid strata of the earth, those bulwarks of the field and shore, without acknowledging the provident design of nature in giving as much permanency to our continent, as is consistent with sufficient fertility; and we cannot contemplate the necessary waste of a present continent, without perceiving the means for laying the foundation of another. but the evidence of those truths is not open to a vulgar view; _media_ are required, or much reasoning; and between the first link and the last, in this chain, what a distance, from the wasting of hard bodies upon the surface of the earth, to the formation of a solid rock at the bottom of the sea. chap. xiv. _summary of the doctrine which has been now illustrated._ the system of this earth appears to comprehend many different operations; and it exhibits various powers co-operating for the production of those effects which we perceive. of this we are informed by studying natural appearances; and in this manner we are led to understand the nature of things, in knowing causes. that our land, which is now above the level of the sea, had been formerly under water, is a fact for which there is every where the testimony of a multitude of observations. this indeed is a fact which is admitted upon all hands; it is a fact upon which the speculations of philosophers have been already much employed; but it is a fact still more important, in my opinion, than it has been ever yet considered. it is not, however, as a solitary fact that any rational system may be founded upon this truth, that the earth had been formerly at the bottom of the sea; we must also see the nature and constitution of this earth as necessarily subsisting in continual change; and we must see the means employed by nature for constructing a continent of solid land in the fluid bosom of the deep. it is then that we may judge of that design, by finding ends and means contrived in wisdom, that is to say, properly adapted to each other. we have now given a theory founded upon the actual state of this earth, and the appearances of things, so far as they are changing; and we have, in support of that theory, adduced the observations of scientific men, who have carefully examined nature and described things in a manner that is clear and intelligible. we are now to take a review of the principle points on which this theory hangs; and to endeavour to point out the importance of the subject, and the proper manner of judging with regard to a theory of the earth, how far it is conform to the general system of nature, which has for object a world. if it should be admitted, that this earth had been formed by the collection of materials deposited within the sea, there will then appear to be certain things which ought to be explained by a theory, before that theory be received as belonging to this earth. these are as follows: _first_, we ought to show how it came about that this whole earth, or by far the greatest part in all the quarters of the globe, had been formed of transported materials collected together in the sea. it must be here remembered, that the highest of our mountainous countries are equally formed of those travelled materials as are the lowest of our plains; we are not therefore to have recourse to any thing that we see at present for the origin of those materials which actually compose the earth; and we must show from whence had come those travelled materials, manufactured by water, which were employed in composing the highest places of our land. _secondly_, we must explain how those loose and incoherent materials had been consolidated, as we find they are at present. we are not here to allow ourselves the liberty, which naturalists have assumed without the least foundation, of explaining every thing of this sort by _infiltration_, a term in this case expressing nothing but our ignorance. _thirdly_, the strata are not always equally consolidated. we often find contiguous strata in very different states with respect to solidity; and sometimes the most solid masses are found involved in the most porous substance. some explanation surely would be expected for this appearance, which is of a nature so conclusive as ought to attract the attention of a theorist. _fourthly_, it is not sufficient to show how the earth in general had been consolidated; we must also explain, how it comes to pass that the consolidated bodies are always broken and intersected by veins and fissures. in this case, the reason commonly given, that the earth exposed to the atmosphere had shrunk like moist clay, or contracted by the operation of drying, can only show that such naturalists have thought but little upon the subject. the effect in no shape or degree corresponds to that cause; and veins and fissures, in the solid bodies, are no less frequent under the level of the sea, than on the summits of our mountains. _fifthly_, having found a cause for the fracture and separation of the solid masses, we must also tell from whence the matter with which those chasms are filled, matter which is foreign both to the earth and sea, had been introduced into the veins that intersect the strata. if we fail in this particular, what credit could be given to such hypotheses as are contrived for the explanation of more ambiguous appearances, even when those suppositions should appear most probable? _sixthly_, supposing that hitherto every thing had been explained in the most satisfactory manner, the most important appearances of our earth still remain to be considered. we find those strata that were originally formed continuous in their substance, and horizontal in their position, now broken, bended, and inclined, in every manner and degree; we must give some reason in our theory for such a general changed state and disposition of things; and we must tell by what power this event, whether accidental or intended, had been brought about. _lastly_, whatever powers had been employed in preparing land, while situated under water, or at the bottom of the sea, the most powerful operation yet remains to be explained; this is the means by which the lowest surface of the solid globe was made to be the highest upon the earth. unless we can show a power of sufficient force, and placed in a proper situation for that purpose, our theory would go for nothing, among people who investigate the nature of things, and who, founding on experience, reason by induction from effect to cause. nothing can be admitted as a theory of the earth which does not, in a satisfactory manner, give the efficient causes for all these effects already enumerated. for, as things are universally to be acknowledged in the earth, it is essential in a theory to explain those natural appearances. but this is not all. we live in a world where order every where prevails; and where final causes are as well known, at least, as those which are efficient. the muscles, for example, by which i move my fingers when i write, are no more the efficient cause of that motion, than this motion is the final cause for which the muscles had been made. thus, the circulation of the blood is the efficient cause of life; but, life is the final cause, not only for the circulation of the blood, but for the revolution of the globe: without a central luminary, and a revolution of the planetary body, there could not have been a living creature upon the face of this earth; and, while we see a living system on this earth, we must acknowledge, that in the solar system we see a final cause. now, in a theory which considers this earth as placed in a system of things where ends are at least attained, if not contrived in wisdom, final causes must appear to be an object of consideration, as well as those which are efficient. a living world is evidently an object in the design of things, by whatever being those things had been designed, and however either wisdom or folly may appear in that design. therefore the explanation, which is given of the different phenomena of the earth, must be consistent with the actual constitution of this earth as a living world, that is, a world maintaining a system of living animals and plants. not only are no powers to be employed that are not natural to the globe, no action to be admitted of except those of which we know the principle, and no extraordinary events to be alledged in order to explain a common appearance, the powers of nature are not to be employed in order to destroy the very object of those powers; we are not to make nature act in violation to that order which we actually observe, and in subversion of that end which is to be perceived in the system of created things. in whatever manner, therefore, we are to employ the great agents, fire and water, for producing those things which appear, it ought to be in such a way as is consistent with the propagation of plants and life of animals upon the surface of the earth. chaos and confusion are not to be introduced into the order of nature, because certain things appear to our partial views as being in some disorder. nor are we to proceed in feigning causes, when those seem insufficient which occur in our experience. animal life being thus considered as an object in the view of nature, we are to consider this earth as being the means appointed for that end; and then the question is suggested, how far wisdom may appear in the constitution of this earth, as being _means_ properly adapted to the system of animal life, which is evidently the end. this is taking for granted, that there is a known system of the earth which is to be tried--how far properly adapted to the end intended in nature. but, it is this very system of the earth which is here the subject of investigation; and, it is in order to discover the _true system_ that we are to examine, by means of final causes, every theory which pretends to show the nature of that system, or to assign efficient causes to physical events. here then we have a rule to try the propriety of every operation which should be acknowledged as in the system of nature, or as belonging to the theory of this earth. it is not necessary that we should see the propriety of every natural operation; our natural ignorance precludes us from any title to form a judgment in things of which we are not properly informed; but, no suppositions of events, or explanations of natural appearances, are to be admitted into our theory, if the propriety of those alledged operations is not made to appear. we are now to make an application. this earth, which is now dry land, was under water, and was formed in the sea. here is a matter of fact, and not of theory, so far as it can be made as evident as any thing of which we have not seen the immediate act or execution. but the propriety of this matter of fact is only to be perceived in making the following acknowledgment, that the origin of this earth is necessarily placed in the bottom of the sea. in supposing any other origin to this habitable earth, we would see the impropriety of having it covered with water, or drowned in the sea. but, being formed originally at the bottom of the sea, if we can explain the phenomena of this earth by natural causes, we will acknowledge the wisdom of those means, by which the earth, thus formed at the bottom of the sea, had been perfected in its nature, and made to fulfil the purpose of its intention, by being placed in the atmosphere. if the habitable earth does not take its origin in the waters of the sea, the washing away of the matter of this earth into the sea would put a period to the existence of that system which forms the admirable constitution of this living world. but, if the origin of this earth is founded in the sea, the matter which is washed from our land is only proceeding in the order of the system; and thus no change would be made in the general system of this world, although this particular earth, which we possess at present, should in the course of nature disappear. it has already been our business to show that the land is actually wasted universally, and carried away into the sea. now, what is the final cause of this event?--is it in order to destroy the system of this living world, that the operations of nature are thus disposed upon the surface of this earth? or, is it to perpetuate the progress of that system, which, in other respects, appears to be contrived with so much wisdom? here are questions which a theory of the earth must solve; and here indeed, must be found the most material part by far of any theory of the earth. for, as we are more immediately concerned with the operations of the surface, it is the revolutions of that surface which forms, for us, the most interesting subject of inquiry. thus we are led to inquire into the final cause of things, while we investigate an operation of such magnitude and importance, as is that of forming land of sea, and sea of land, of apparently reversing nature, and of destroying that which is so admirably adapted to its purpose. was it the work of accident, or effect of an occasional transaction, that by which the sea had covered our land? or, was it the intention of that mind which formed the matter of this globe, which endued that matter with its active and its passive powers, and which placed it with so much wisdom among a numberless collection of bodies, all moving in a system? if we admit the first, the consequence of such a supposition would be to attribute to chance the constitution of this world, in which the systems of life and sense, of reason and intellect, are necessarily maintained. if again we shall admit, that there is intention in the cause by which the present earth had been removed from the bottom of the sea, we may then inquire into the nature of that system in which a habitable earth, possessed of beauty, arranged in order, and preserved with economy, had been formed by the mixture and combination of the different elements, and made to rise out of the wreck of a former world. in examining the structure of our earth, we find it no less evidently formed of loose and incoherent materials, than that those materials had been collected from different parts, and gathered together at the bottom of the sea. consequently, if this continent of land, first collected in the sea, and then raised above its surface, is to remain a habitable earth, and to resist the moving waters of the globe, certain degrees of solidity or consolidation must be given to that collection of loose materials; and certain degrees of hardness must be given to bodies which were soft or incoherent, and consequently so extremely perishable in the situation where they now are placed. but, at the same time that this earth must have solidity and hardness to resist the sudden changes which its moving fluids would occasion, it must be made subject to decay and, waste upon the surface exposed to the atmosphere; for, such an earth as were made incapable of change, or not subject to decay, could not afford that fertile soil which is required in the system of this world, a soil on which depends the growth of plants and life of animals,--the end of its intention. now, we find this earth endued precisely with that degree of hardness and consolidation, as qualifies it at the same time to be a fruitful earth, and to maintain its station with all the permanency compatible with the nature of things, which are not formed to remain unchangeable. thus we have a view of the most perfect wisdom, in the contrivance of that constitution by which the earth is made to answer, in the best manner possible, the purpose of its intention, that is, to maintain and perpetuate a system of vegetation, or the various race of useful plants, and a system of living animals, which are in their turn subservient to a system still infinitely more important, i mean, a system of intellect. without fertility in the earth, many races of plants and animals would soon perish, or be extinct; and, without permanency in our land, it were impossible for the various tribes of plants and animals to be dispersed over all the surface of a changing earth. the fact is, that fertility, adequate to the various ends in view, is found in all the quarters of the world, or in every country of the earth; and, the permanency of our land is such, as to make it appear unalterable to mankind in general, and even to impose upon men of science, who have endeavoured to persuade us that this earth is not to change. nothing but supreme power and wisdom could have reconciled those two opposite ends of intention, so as both to be equally pursued in the system of nature, and both so equally attained as to be imperceptible to common observation, and at the same time a proper object for the human understanding. we thus are led to inquire into the efficient causes of this constitution of things, by which solidity and stability had been bestowed upon a mass of loose materials, and by which this solid earth, formed first at the bottom of the sea, had been placed in the atmosphere, where plants and animals find the necessary conditions of their life. now, we have shown, that subterraneous fire and heat had been employed in the consolidation of our earth, and in the erection of that consolidated body into the place of land. the prejudices of mankind, who cannot see the steps by which we come at this conclusion, are against the doctrine; but, prejudice must give way to evidence. no other theory will in any degree explain appearances, while almost every appearance is easily explained by this theory. we do not dispute the chymical action and efficacy of water, or any other substance which is found among the materials collected at the bottom of the sea; we only mean to affirm, that every action of this kind is incapable of producing perfect solidity in the body of earth in that situation of things, whatever time should be allowed for that operation, and that whatever may have been the operations of water, aided by fire, and evaporated by heat, the various appearances of mineralization, (every where presented to us in the solid earth, and the most perfect objects of examination), are plainly inexplicable upon the principle of aqueous solution. on the other hand, the operation of heat, melting incoherent bodies, and introducing softness into rigid substances which are to be united, is not only a cause which is proper to explain the effects in question, but also appears, from a multitude of different circumstances, to have been actually exerted among the consolidated bodies of our earth, and in the mineral veins with which the solid bodies of the earth abound. the doctrine, therefore, of our theory is briefly this, that, whatever may have been the operation of dissolving water, and the chymical action of it upon the materials accumulated at the bottom of the sea, the general solidity of that mass of earth, and the placing of it in the atmosphere above the surface of the sea, has been the immediate operation of fire or heat melting and expanding bodies. here is a proposition which may be tried, in applying it to all the phenomena of the mineral region; so far as i have seen, it is perfectly verified in that application. we have another proposition in our theory; one which is still more interesting to consider. it is this, that as, in the mineral regions, the loose or incoherent materials of our land had been consolidated by the action of heat; so, upon the surface of this earth exposed to the fluid elements of air and water, there is a necessary principle of dissolution and decay, for that consolidated earth which from the mineral region is exposed to the day. the solid body being thus gradually impaired, there are moving powers continually employed, by which the summits of our land are constantly degraded, and the materials of this decaying surface travelled towards the coast. there are other powers which act upon the shore, by which the coast is necessarily impaired, and our land subjected to the perpetual incroachment of the ocean. here is a part of the theory with which every appearance of the surface may be compared. i am confident that it will stand the test of the most rigid examination; and that nothing but the most inconsiderate judgment may mistake a few appearances, which, when properly understood, instead of forming any subject of objection to the theory, will be found to afford it every reasonable support or confirmation. we have now seen, that in every quarter of the globe, and in every climate of the earth, there is formed, by means of the decay of solid rocks, and by the transportation of those moveable materials, that beautiful system of mountains and valleys, of hills and plains, covered with growing plants, and inhabited by animals. we have seen, that, with this system of animal and vegetable economy, which depends on soil and climate, there is also a system of moving water, poured upon the surface of the earth[ ], in the most beneficial manner possible for the use of vegetation, and the preservation of our soil; and that this water is gathered together again by running to the lowest place, in order to avoid accumulation of water upon the surface, which would be noxious. [footnote : see dissertations upon subjects of natural philosophy, part i.] it is in this manner that we first have streams or torrents, which only run in times of rain. but the rain-water absorbed into the earth is made to issue out in springs, which run perpetually, and which, gathering together as they run, form rivulets, watering valleys, and delighting the various inhabitants of this earth. the rivulets again are united in their turn, and form those rivers which overflow our plains, and which alternately bring permanent fertility and casual devastation to our land. those rivers, augmenting in their volume as they unite, pour at last their mighty waters into the ocean; and thus is completed that circulation of wholesome fluids, which the earth requires in order to be a habitable world. our theory farther shows, that in the ocean there is a system of animals which have contributed so materially to the formation of our land. these animals are necessarily maintained by the vegetable provision, which is returned in the rivers to the sea, and which the land alone or principally produces. thus we may perceive the mutual dependence upon each other of those two habitable worlds,--the fluid ocean and the fertile earth. the land is formed in the sea, and in great part by inhabitants of that fluid world. but those animals, which form with their _exuviae_ such a portion of the land, are maintained, like those upon the surface of the earth, by the produce of that land to which they formerly had contributed. thus the vegetable matter, which is produced upon the surface of the earth in such abundance for the use of animals, and which, in such various shapes, is carried by the rivers into the sea, there sustains that living system which is daily employed to make materials for a future land. here is a compound system of things, forming together one whole living world; a world maintaining an almost endless diversity of plants and animals, by the disposition of its various parrs, and by the circulation of its different kinds of matter. now, we are to examine into the necessary consequence of this disposition of things, where the matter of this active world is perpetually moved, in that salutary circulation by which provision is so wisely made for the growth and prosperity of plants, and for the life and comfort of its various animals. if, in examining this subject, we shall find that there is nothing in the system but what is necessary, that is, nothing in the means employed but what the importance of the end requires; if we shall find that the end is steadily pursued, and that there is no deficiency in the means which are employed; and if it shall be acknowledged that the end which is attained is not idle or insignificant, we then may draw this conclusion, that such a system is in perfect wisdom; and therefore that this system, so far as it is found corresponding properly with natural appearances, is the system of nature, and not the creature of imagination. let us then take a cursory view of this system of things, upon which we have proceeded in our theory, and upon which the constitution of this world seems to depend. our solid earth is every where wasted, where exposed to the day. the summits of the mountains are necessarily degraded. the solid and weighty materials of those mountains are every where urged through the valleys, by the force of running water. the soil, which is produced in the destruction of the solid earth, is gradually travelled by the moving water, but is constantly supplying vegetation with its necessary aid. this travelled soil is at last deposited upon the coast, where it forms most fertile countries. but the billows of the ocean agitate the loose materials upon the shore, and wear away the coast, with the endless repetitions of this act of power, or this imparted force. thus the continent of our earth, sapped in its foundation, is carried away into the deep, and sunk again at the bottom of the sea, from whence it had originated. we are thus led to see a circulation in the matter of this globe, and a system of beautiful economy in the works of nature. this earth, like the body of an animal, is wasted at the same time that it is repaired. it has a state of growth and augmentation; it has another state, which is that of diminution and decay. this world is thus destroyed in one part, but it is renewed in another; and the operations by which this world is thus constantly renewed, are as evident to the scientific eye, as are those in which it is necessarily destroyed. the marks of the internal fire, by which the rocks, beneath the sea are hardened, and by which the land is produced above the surface of the sea, have nothing in them which is doubtful or ambiguous. the destroying operations again, though placed within the reach of our examination, and evident almost to every observer, are no more acknowledged by mankind, than is that system of renovation which philosophy alone discovers. it is only in science that any question concerning the origin and end of things is formed; and it is in science only that the resolution of those questions is to be attained. the natural operations of this globe, by which the size and shape of our land are changed, are so slow as to be altogether imperceptible to men who are employed in pursuing the various occupations of life and literature. we must not ask the industrious inhabitant, for the end or origin of this earth: he sees the present, and he looks no farther into the works of time than his experience can supply his reason. we must not ask the statesman, who looks into the history of time past, for the rise and fall of empires; he proceeds upon the idea of a stationary earth, and most justly has respect to nothing but the influence of moral causes. it is in the philosophy of nature that the natural history of this earth is to be studied; and we must not allow ourselves ever to reason without proper data, or to fabricate a system of apparent wisdom in the folly of a hypothetical delusion. when, to a scientific view of the subject, we join the proof which has been given, that in all the quarters of the globe, in every place upon the surface of the earth, there are the most undoubted marks of the continued progress of those operations which wear away and waste the land, both in its height and width, its elevation and extention, and that for a space of duration in which our measures of time are lost, we must sit down contented with this limitation of our retrospect, as well as prospect, and acknowledge, that it is in vain to seek for any computation of the time, during which the materials of this earth had been prepared in a preceding world, and collected at the bottom of a former sea. the system of this earth will thus appear to comprehend many different operations, or it exhibits various powers co-operating for the production of those appearances which we properly understand in knowing causes. thus, in order to understand the natural conformation of this country, or the particular shape of any other place upon the globe, it is not enough to see the effects of those powers which gradually waste and wear away the surface, we must also see how those powers affecting the surface operate, or by what principle they act. besides, seeing those powers which are employed in thus changing the surface of the earth, we must also observe how their force is naturally augmented with the declivity of the ground on which they operate. neither is it sufficient to understand by what powers the surface is impaired, for, it may be asked, why, in equal circumstances, one part is more impaired than another; this then leads to the examination of the mineral system, in which are determined the hardness and solidity, consequently, the permanency of those bodies of which our land is composed; and here are sources of indefinite variety. in the system of the globe every thing must be consistent. the changing and destroying operations of the surface exposed to the sun and influences of the atmosphere, must correspond to those by which land is composed at the bottom of the sea; and the consolidating operations of the mineral region must correspond to those appearances which in the rocks, the veins, and solid stones, give such evident, such universal testimony of the power of fire, in bringing bodies into fusion, or introducing fluidity, the necessary prelude to solidity and concretion. those various powers of nature have thus been employed in the theory, to explain things which commonly appear; or rather, it is from things which universally appear that causes have been concluded, upon scientific principles, for those effects. a system is thus formed, in generalising all those different effects, or in ascribing all those particular operations to a general end. this end, the subject of our understanding, is then to be considered as an object of design; and, in this design, we may perceive, either wisdom, so far as the ends and means are properly adapted, or benevolence, so far as that system is contrived for the benefit of beings who are capable of suffering pain and pleasure, and of judging good and evil. but, in this physical dissertation, we are limited to consider the manner in which things present have been made to come to pass, and not to inquire concerning the moral end for which those things may have been calculated. therefore, in pursuing this object, i am next to examine facts, with regard to the mineralogical part of the theory, from which, perhaps, light may be thrown upon the subject; and to endeavour to answer objections, or solve difficulties, which may naturally occur from the consideration of particular appearances. end of volume second. transcriber's note: the punctuation and spelling from the original text have been faithfully preserved. only obvious typographical errors have been corrected. the pointing finger symbol in the advertisement section is represented by -->. the cruise of the betsey; or, a summer ramble among the fossiliferous deposits of the hebrides. with rambles of a geologist; or, ten thousand miles over the fossiliferous deposits of scotland. by hugh miller, ll. d., author of "the old red sandstone," "footprints of the creator," "my schools and schoolmasters," "the testimony of the rocks," etc. boston: gould and lincoln, washington street. new york: sheldon and company. cincinnati: geo. s. blanchard. . entered according to act of congress, in the year , by gould and lincoln, in the clerk's office of the district court of the district of massachusetts. authorized edition. by a special arrangement with the late hugh miller, gould and lincoln became the authorized american publishers of his works. by a similar arrangement made with the family since his decease, they will also publish his posthumous works, of which the present volume is the first. electrotyped by w. f. draper, andover, mass. printed by geo. c. rand & avery, boston. preface. naturalists of every class know too well how hugh miller died--the victim of an overworked brain; and how that bright and vigorous spirit was abruptly quenched forever. during the month of may ( ) mrs. miller came to malvern, after recovering from the first shock of bereavement, in search of health and repose, and evidently hoping to do justice, on her recovery, to the literary remains of her husband. unhappily the excitement and anxiety naturally attaching to a revision of her husband's works proved over much for one suffering under such recent trial, and from an affection of the brain and spine which ensued; and, in consequence, mrs. miller has been forbidden, for the present, to engage in any work of mental labor. under these circumstances, and at mrs. miller's request, i have undertaken the editing of "the cruise of the betsey, or a summer ramble among the fossiliferous deposits of the hebrides," as well as "the rambles of a geologist," hitherto unpublished, save as a series of articles in the "witness" newspaper. the style and arguments of hugh miller are so peculiarly his own, that i have not presumed to alter the text, and have merely corrected some statements incidental to the condition of geological knowledge at the time this work was penned. "the cruise of the betsey" was written for that well-known paper the "witness" during the period when a disputation productive of much bitter feeling waged between the free and established churches of scotland; but as the disruption and its history possesses little interest to a large class of the readers of this work, who will rejoice to follow their favorite author among the isles and rocks of the "bonnie land," i have expunged _some_ passages, which i am assured the author would have omitted had he lived to reprint this interesting narrative of his geological rambles. hugh miller battled nobly for his faith while living. the sword is in the scabbard: let it rest! w.s. symonds. pendock rectory, april , . contents. part i. the cruise of the betsey. chapter i. preparation--departure--recent and ancient monstrosities--a free church yacht--down the clyde--jura--prof. walker's experiment--whirlpool near scarba--geological character of the western highlands--an illustration--different ages of outer and inner hebrides--mt. blanc and the himalayas "mere upstarts"--esdaile quarries--oban--a section through conglomerate and slate examined--mcdougal's dog-stone--power of the ocean to move rocks--sound of mull--the betsey--the minister's cabin--village of tobermory--the "florida," a wreck of the invincible armada--geologic exploration and discovery--at anchor. chapter ii. the minister's larder--no harbor--eigg shoes--_tormentilla erecta_--for the _witness'_ sake--eilean chaisteil--appearance of eigg--chapel of st. donan--shell-sand--origin of secondary calcareous rock suggested--exploration of eigg--pitchstone veins--a bone cave--massacre at eigg--grouping of human bones in the cave--relics--the horse's tooth--a copper sewing needle--teeth found--man a worse animal than his teeth show him to have been designed for--story of the massacre--another version--scuir of eigg--the scuir a giant's causeway--character of the columns--remains of a prostrate forest. chapter iii. structure of the scuir--a stray column--the piazza--a buried pine forest the foundation of the scuir--geological poachers in a fossil preserve--_pinites eiggensis_--its description--witham's experiments on fossil pine of eigg--rings of the pine--ascent of the scuir--appearance of the top--white pitchstone--mr. greig's discovery of pumice--a sunset scene--the manse and the yacht--the minister's story--a cottage repast--american timber drifted to the hebrides--agency of the gulf stream--the minister's sheep. chapter iv. an excursion--the chain of crosses--bay of laig--island of rum--description of the island--superstitions banished by pure religion--fossil shells--remarkable oyster bed--new species of belemnite--oölitic shells--white sandstone precipices--gigantic petrified mushrooms--"christabel" in stone--musical sand--_jabel nakous_, or mountain of the bell--experiments of travellers at _jabel nakous_--welsted's account--_reg-rawan_, or the moving sand--the musical sounds inexplicable--article on the subject in the north british review. chapter v. trap-dykes--"cotton apples"--alternation of lacustrine with marine remains--analogy from the beds of esk--aspect of the island on its narrow front--the puffin--ru stoir--development of old red sandstone--striking columnar character of ru stoir--discovery of reptilian remains--john stewart's wonder at the bones in the stones--description of the bones--"dragons, gorgons, and chimeras"--exploration and discovery pursued--the midway shieling--a celtic welcome--return to the yacht--"array of fossils new to scotch geology"--a geologist's toast--hoffman and his fossil. chapter vi. something for non-geologists--man destructive--a better and last creation coming--a rainy sabbath--the meeting house--the congregation--the sermon in gaelic--the old wondrous story--the drunken minister of eigg--presbyterianism without life--dr. johnson's account of the conversion of the people of rum--romanism at eigg--the two boys--the freebooter of eigg--voyage resumed--the homeless minister--harbor of isle ornsay--interesting gneiss deposit--a norwegian keep--gneiss at knock--curious chemistry--sea-cliffs beyond portsea--the goblin luidag--scenery of skye. chapter vii. exploration resumed--geology of rasay--an illustration--the storr of skye--from portree to holm--discovery of fossils--an island rain--sir r. murchison--labor of drawing a geological line--three edinburgh gentlemen--_prosopolepsia_--wrong surmises corrected--the mail gig--the portree postmaster--isle ornsay--an old acquaintance--reminiscences--a run for rum--"semi-fossil madeira"--idling on deck--prognostics of a storm--description of the gale--loch scresort--the minister's lost _sou-wester_--the free church gathering--the weary minister. chapter viii. geology of rum--its curious character illustrated--rum famous for bloodstones--red sandstones--"scratchings" in the rocks--a geological inscription without a key--the lizard--vitality broken into two--illustrations--speculation--scuir more--ascent of the scuir--the bloodstones--an illustrative set of the gem--m'culloch's pebble--a chemical problem--the solitary shepherd's house--sheep _versus_ men--the depopulation of rum--a haul of trout--rum mode of catching trout--at anchor in the bay of glenelg. chapter ix. kyles of skye--a gneiss district--kyle rhea--a boiling tide--a "take" of sillocks--the betsey's "paces"--in the bay at broadford--rain--island of pabba--description of the island--its geological structure--astrea--polypifers--_gryphoea incurva_--three groups of fossils in the lias of skye--abundance of the petrifactions of pabba--scenery--pabba a "piece of smooth, level england"--fossil shells of pabba--- voyage resumed--kyle akin--ruins of castle maoil--a "thornback" dinner--the bunch of deep sea tangle--the caileach stone--kelp furnaces--escape of the betsey from sinking. chapter x. isle orusay--the sabbath--a sailor-minister's sermon for sailors--the scuir sermon--loch carron--groups of moraines--a sheep district--the editor of the _witness_ and the establishment clergyman--dingwall--conon-side revisited--the pond and its changes--new faces.--the stonemason's mark--the burying-ground of urquhart--an old acquaintance--property qualification for voting in scotland--montgerald sandstone quarries--geological science in cromarty--the danes at cromarty--the danish professor and the "old red sandstone"--harmonizing tendencies of science. chapter xi. ichthyolite beds--an interesting discovery--two storeys of organic remains in the old red sandstone--ancient ocean of lower old red--two great catastrophes--ancient fish scales--their skilful mechanism displayed by examples--bone lips--arts of the slater and tiler as old as old red sandstone--jet trinkets--flint arrow-heads--vitrified forts of scotland--style of grouping lower old red fossils--illustration from cromarty fishing phenomena--singular remains of holoptychius--ramble with mr. robert dick--color of the planet mars--tombs never dreamed of by hervey--skeleton of the bruce--gigantic holoptychius--"coal money currency"--upper boundary of lower old red--every one may add to the store of geological facts--discoveries of messrs. dick and peach. chapter xii. ichthyolite beds of clune and lethenbarn--limestone quarry--destruction of urns and sarcophagi in the lime-kiln--nodules opened--beautiful coloring of the remains--patrick duff's description--new genus of morayshire ichthyolite described--form and size of the nodules or stone coffins--illustration from mrs. marshall's cements--forest of darnaway--the hill of berries--sluie--elgin--outliers of the weald and the oölite--description of the weald at linksfield--mr. duff's _lepidotus minor_--eccentric types of fish scales--visit to the sandstones of scat-craig--fine suit of fossils at scat-craig--true graveyard bones, not mere impressions--varieties of pattern--the diker's "carved flowers"--_stagonolepis_, a new genus--termination of the ramble. chapter xiii. supplementary. supplementary--isolated reptile remains in eigg--small isles revisited--the betsey again--storm bound--tacking--becalmed--medusæ caught and described--rain--a shoal of porpoises--change of weather--the bed-ridden woman--the poor law act for scotland--geological excursion--basaltic columns--oölitic beds--abundance of organic remains--hybodus teeth--discovery of reptile remains _in situ_--musical sand of laig re-examined--explanation suggested--sail for isle ornsay--anchored clouds--a leak sprung--peril of the betsey--at work with pump and pails--safe in harbor--return to edinburgh. part ii. rambles of a geologist. chapter i. embarkation--a foundered vessel--lateness of the harvest dependent on the geological character of the soil--a granite harvest and an old red harvest--cottages of redstone and of granite--arable soil of scotland the result of a geological grinding agency--locality of the famine of --mr. longmuir's fossils--geology necessary to a theologian--popularizers of science when dangerous--"constitution of man," and "vestiges of creation"--atop of the banff coach--a geologist's field equipment--the trespassing "stirk"--silurian schists inlaid with old red--bay of gamrie, how formed--gardenstone--geological free-masonry illustrated--how to break an ichthyolite nodule--an old rhyme mended--a raised beach--fossil shells--scotland under water at the time of the boulder-clays. chapter ii. character of the rocks near gardenstone--a defunct father-lasher--a geological inference--village of gardenstone--the drunken scot--gardenstone inn--lord gardenstone--a tempest threatened--the author's ghost story--the lady in green--her appearance and tricks--the rescued children--the murdered peddler and his pack--where the green dress came from--village of macduff--peculiar appearance of the beach at the mouth of the deveron--dr. emslie's fossils--_pterichthys quadratus_--argillaceous deposits of blackpots--pipe-laying in scotland--fossils of blackpots clay--mr. longmuir's description of them--blackpots deposit a re-formation of a liasic patch--period of its formation. chapter iii. from blackpots to portsoy--character of the coast--burn of boyne--fever phantoms--graphic granite--maupertuis and the runic inscription--explanation of the _quo modo_ of graphic granite--portsoy inn--serpentine beds--portsoy serpentine unrivalled for small ornaments--description of it--significance of the term _serpentine_--elizabeth bond and her "letters"--from portsoy to cullen--attritive power of the ocean illustrated--the equinoctial--from cullen to fochabers--the old red again--the old pensioner--fochabers--mr. joss, the learned mail-guard--the editor a sort of coach-guard--on the coach to elgin--geology of banffshire--irregular paging of the geologic leaves--geologic map of the county like joseph's coat--striking illustration. chapter iv. yellow-hued houses of elgin--geology of the country indicated by the coloring of the stone houses--fossils of old red north of the grampians different from those of old red south--geologic formations at linksfield difficult to be understood--ganoid scales of the wealden--sudden reaction, from complex to simple, in the scales of fishes--pore-covered scales--extraordinary amount of design exhibited in ancient ganoid scales--holoptychius scale illustrated by cromwell's "fluted pot"--patrick duff's geological collection--elgin museum--fishes of the ganges--armature of ancient fishes--compensatory defences--- the hermit-crab--spines of the pimelodi--ride to campbelton--theories of the formation of ardersier and fortrose promontories--tradition of their construction by the wizard, michael scott--a region of legendary lore. chapter v. rosemarkie and its scaurs--kaes' craig--a jackdaw settlement--"rosemarkie kaes" and "cromarty cooties"--"the danes," a group of excavations--at home in cromarty--the boulder-clay of cromarty "begins to tell its story"--one of its marked scenic peculiarities--hints to landscape painters--"samuel's well"--a chain of bogs geologically accounted for--another scenic peculiarity--"_ha-has_ of nature's digging"--the author's earliest field of hard labor--picturesque cliff of boulder-clay--scratchings on the sandstone--invariable characteristic of true boulder-clay--scratchings on pebbles in the line of the longer axis--illustration from the boulder-clay of banff. chapter vi. organisms of the boulder-clay not unequivocal--first impressions of the boulder-clay--difficulty of accounting for its barrenness of remains--sir charles lyell's reasoning--a fact to the contrary--human skull dug from a clay-bank--the author's change of belief respecting organic remains of the boulder-clay--shells from the clay at wick--questions respecting them settled--conclusions confirmed by mr. dick's discoveries at thurso--sir john sinclair's discovery of boulder-clay shells in --comminution of the shells illustrated--_cyprina islandica_--its preservation in larger proportions than those of other shells accounted for--boulder-clays of scotland reformed during the existing geological epoch--scotland in the period of the boulder-clay "merely three detached groups of islands"--evidence of the subsidence of the land in scotland--confirmed by rev. mr. cumming's conclusion--high-lying granite boulders--marks of a succeeding elevatory period--scandinavia now rising--autobiography of a boulder desirable--a story of the supernatural. chapter vii. relation of the deep red stone of cromarty to the ichthyolite beds of the system--ruins of a fossil-charged bed--journey to avoch--red dye of the boulder-clay distinct from the substance itself--variation of coloring in the boulder-clay red sandstone accounted for--hard-pan how formed--a reformed garden--an ancient battle-field--antiquity of geologic and human history compared--burn of killein--observation made in boyhood confirmed--fossil-nodules--fine specimen of _coccosteus decipiens_--blank strata of old red--new view respecting the rocks of black isle--a trip up moray and dingwall friths--altered color of the boulder-clay--up the auldgrande river--scenery of the great conglomerate--graphic description--laidlaw's boulder--_vaccinium myrtillus_--profusion of travelled boulders--the boulder _clach malloch_--its zones of animal and vegetable life. chapter viii. imaginary autobiography of the _clach malloch_ boulder--its creation--its long night of unsummed centuries--laid open to light on a desert island--surrounded by an arctic vegetation--undermined by the rising sea--locked up and floated off on an ice-field--at rest on the sea-bottom--another night of unsummed years--the boulder raised again above the waves by the rising of the land--beholds an altered country--pine forests and mammals--another period of ages passes--the boulder again floated off by an iceberg--finally at rest on the shore of cromarty bay--time and occasion of naming it--strange phenomena accounted for by earthquakes--how the boulder of petty bay was moved--the boulder of auldgrande--the old highland paupers--the little parsi girl--her letter to her papa--but one human nature on earth--journey resumed--conon burying ground--an aged couple--gossip. chapter ix. the great conglomerate--its undulatory and rectilinear members--knock farril and its vitrified fort--the old highlanders an observant race--the vein of silver--summit of knock farril--mode of accounting for the luxuriance of herbage in the ancient scottish fortalices--the green graves of culloden--theories respecting the vitrification of the hill-forts--combined theories of williams and mackenzie probably give the correct account--the author's explanation--transformations of fused rocks--strathpetlier--the spa--permanent odoriferous qualities of an ancient sea-bottom converted into rock--mineral springs of the spa--infusion of the powdered rock a substitute--belemnite water--the lively young lady's comments--a befogged country seen from a hill-top--ben-wevis--journey to evanton--a geologist's night-mare--the route home--ruins of craig house--incompatibility of tea and ghosts--end of the tour. chapter x. recovered health--journey to the orkneys--aboard the steamer at wick--mr. bremner--masonry of the harbor of wick--the greatest blunders result from good rules misapplied--mr. bremner's theory about sea-washed masonry--singular fracture of the rock near wick--the author's mode of accounting for it--"simple but not obvious" thinking--mr. bremner's mode of making stone erections under water--his exploits in raising foundered vessels--aspect of the orkneys--the ungracious schoolmaster--in the frith of kirkwall--cathedral of st magnus--appearance of kirkwall--its "perished suppers"--its ancient palaces--blunder of the scotch aristocracy--the patronate wedge--breaking ground in orkney--minute gregarious coccosteus--true position of the coccosteus' eyes--ruins of one of cromwell's forts--antiquities of orkney--the cathedral--its sculptures--the mysterious cell--prospect from the tower--its chimes--ruins of castle patrick. chapter xi. the bishop's palace at orkney--haco the norwegian--icelandic chronicle respecting his expedition to scotland--his death--removal of his remain to norway--why norwegian invasion ceased--straw-plaiting--the lassies of orkney--orkney type of countenance--celtic and scandinavian--an accomplished antiquary--old manuscripts--an old tune book--manuscript letter of mary queen of scots--letters of general monck--the fearless covenanter--cave of the rebels--why the tragedy of "gustavus vasa" was prohibited--quarry of pickoquoy--its fossil shells--journey to stromness--scenery--birth-place of malcolm, the poet--his history--one of his poems--his brother a free church minister--new scenery. chapter xii. hills of orkney--their geologic composition--scene of scott's "pirate"--stromness--geology of the district--"seeking beasts"--conglomerate in contact with granite--a palæozoic hudson's bay--thickness of conglomerate of orkney--oldest vertebrate yet discovered in orkney--its size--figure of a characteristic plate of the asterolepis--peculiarity of old red fishes--length of the asterolepis--a rich ichthyolite bed--arrangement of the layers--queries as to the cause of it--minerals--an abandoned mine--a lost vessel--kelp for iodine--a dangerous coast--incidents of shipwreck--hospitality--stromness museum--diplopterus mistaken for dipterus--their resemblances and differences--visit to a remarkable stack--paring the soil for fuel, and consequent barrenness--description of the stack--wave-formed caves--height to which the surf rises. chapter xiii. detached fossils--remains of the pterichthys--terminal bones of the coccosteus, etc., preserved--internal skeleton of coccosteus--the shipwrecked sailor in the cave--bishop grahame--his character, as drawn by baillie--his successor--ruins of the bishop's country-house--sub-aërial formation of sandstone--formation near new kaye--inference from such formation--tour resumed--loch of stennis--waters of the loch fresh, brackish, and salt--vegetation varied accordingly--change produced in the flounder by fresh water--the standing stones, second only to stonehenge--their purpose--their appearance and situation--diameter of the circle--what the antiquaries say of it--reference to it in the "pirate"--dr. hibbert's account. chapter xiv. on horseback--a pared moor--small landholders--absorption of small holdings in england and scotland--division of land favorable to civil and religious rights--favorable to social elevation--an inland parish--the landsman and lobster--wild flowers of orkney--law of compensation illustrated by the tobacco plant--poverty tends to productiveness--illustrated in ireland--profusion of ichthyolites--orkney a land of defunct fishes--sandwick--a collection of coccostean flags--a quarry full of heads of dipteri--the bergil, or striped wrasse--its resemblance to the dipterus--poverty of the flora of the lower old red--no true coniferous wood in the orkney flagstones--departure for hoy--the intelligent boatman--story of the orkney fisherman. chapter xv. hoy--unique scenery--the dwarfie stone of hoy--sir walter scott's account of it--its associations--inscription of names--george buchanan's consolation--the mythic carbuncle of the hill of hoy--no fossils at hoy--striking profile of sir walter scott on the hill of hoy--sir walter, and shetland and orkney--originals of two characters in "the pirate"--bessie millie--garden of gow, the "pirate"--childhood's scene of byron's "torquil"--the author's introduction to his sister--a german visitor--german and scotch sabbath-keeping habits contrasted--mr. watt's specimens of fossil remains--the only new organism found in orkney--back to kirkwall--to wick--vedder's ode to orkney. the cruise of the betsey. chapter i. preparation--departure--recent and ancient monstrosities--a free church yacht--down the clyde--jura--prof. walker's experiment--whirlpool near scarba--geological character of the western highlands--an illustration--different ages of outer and inner hebrides--mt. blanc and the himalayas "mere upstarts"--esdaile quarries--oban--a section through conglomerate and slate examined--m'dougal's dog-stone--power of the ocean to move rocks--sound of mull--the betsey--the minister's cabin--village of tobermory--the "florida," a wreck of the invincible armada--geologic exploration and discovery--at anchor. the pleasant month of july had again come round, and for full five weeks i was free. chisels and hammers, and the bag for specimens, were taken from their corner in the dark closet, and packed up with half a stone weight of a fine _soft_ conservative edinburgh newspaper, valuable for a quality of preserving old things entire. at noon on st. swithin's day (monday the th), i was speeding down the clyde in the toward castle steamer, for tobermory in mull. in the previous season i had intended passing direct from the oölitic deposits of the eastern coast of scotland, to the oölitic deposits of the hebrides. but the weeks glided all too quickly away among the ichthyolites of caithness and cromarty, and the shells and lignites of sutherland and ross. my friend, too, the rev. mr. swanson, of small isles, on whose assistance i had reckoned, was in the middle of his troubles at the time, with no longer a home in his parish, and not yet provided with one elsewhere; and i concluded he would have but little heart, at such a season, for breaking into rocks, or for passing from the too pressing monstrosities of an existing state of things, to the old lapidified monstrosities of the past. and so my design on the hebrides had to be postponed for a twelvemonth. but my friend, now afloat in his free church yacht, had got a home on the sea beside his island charge, which, if not very secure when nights were dark and winds loud, and the little vessel tilted high to the long roll of the atlantic, lay at least beyond the reach of man's intolerance, and not beyond the protecting care of the almighty. he had written me that he would run down his vessel from small isles to meet me at tobermory, and in consequence of the arrangement i was now on my way to mull. st. swithin's day, so important in the calendar of our humbler meteorologists, had in this part of the country its alternate fits of sunshine and shower. we passed gaily along the green banks of the clyde, with their rich flat fields glittering in moisture, and their lines of stately trees, that, as the light flashed out, threw their shadows over the grass. the river expanded into the estuary, the estuary into the open sea; we left behind us beacon, and obelisk, and rock-perched castle;-- "merrily down we drop below the church, below the tower, below the light house top," and, as the evening fell, we were ploughing the outer reaches of the frith, with the ridgy table-land of ayrshire stretching away, green, on the one side, and the serrated peaks of arran rising dark and high on the other. at sunrise next morning our boat lay, unloading a portion of her cargo, in one of the ports of islay, and we could see the irish coast resting on the horizon to the south and west, like a long undulating bank of thin blue cloud; with the island of rachrin--famous for the asylum it had afforded the bruce when there was no home for him in scotland,--presenting in front its mass of darker azure. on and away! we swept past islay, with its low fertile hills of mica-schist and slate; and jura, with its flat dreary moors, and its far-seen gigantic paps, on one of which, in the last age, professor walker, of edinburgh, set water a-boil with six degrees of heat less than he found necessary for the purpose on the plain below. the professor describes the view from the summit, which includes in its wide circle at once the isle of skye and the isle of man, as singularly noble and imposing; two such prospects more, he says, would bring under the eye the whole island of great britain, from the pentland frith to the english channel. we sped past jura. then came the gulf of coryvrekin, with the bare mountain island of scarba overlooking the fierce, far-famed whirlpool, that we could see from the deck, breaking in long lines of foam, and sending out its waves in wide rings on every side, when not a speck of white was visible elsewhere in the expanse of sea around us. and then came an opener space, studded with smaller islands,--mere hill-tops rising out of the sea, with here and there insulated groups of pointed rocks, the skeletons of perished hills, amid which the tide chafed and fretted, as if laboring to complete on the broken remains their work of denudation and ruin. the disposition of land and water on this coast suggests the idea that the western highlands, from the line in the interior, whence the rivers descend to the atlantic, with the islands beyond to the outer hebrides, are all parts of one great mountainous plane, inclined slantways into the sea. first, the long withdrawing valleys of the main land, with their brown mossy streams, change their character as they dip beneath the sea-level, and become salt-water lochs. the lines of hills that rise over them jut out as promontories, till cut off by some transverse valley, lowered still more deeply into the brine, and that exists as a kyle, minch, or sound, swept twice every tide by powerful currents. the sea deepens as the plain slopes downward; mountain-chains stand up out of the water as larger islands, single mountains as smaller ones, lower eminences as mere groups of pointed rocks; till at length, as we pass outwards, all trace of the submerged land disappears, and the wide ocean stretches out and away its unfathomable depths. the model of some alpine country raised in plaster on a flat board, and tilted slantways, at a low angle, into a basin of water, would exhibit, on a minute scale, an appearance exactly similar to that presented by the western coast of scotland and the hebrides. the water would rise along the hollows, longitudinal and transverse, forming sounds and lochs, and surround, island-like, the more deeply submerged eminences. but an examination of the geology of the coast, with its promontories and islands, communicates a different idea. these islands and promontories prove to be of very various ages and origin. the _outer_ hebrides may have existed as the inner skeleton of some ancient country, contemporary with the main land, and that bore on its upper soils the productions of perished creations, at a time when by much the larger portion of the _inner_ hebrides,--skye, and mull, and the small isles,--existed as part of the bottom of a wide sound, inhabited by the cephalopoda and enaliosaurians of the lias and the oölite. judging from its components, the long island, like the lammermoors and the grampians, may have been smiling to the sun when the alps and the himalaya mountains lay buried in the abyss; whereas the greater part of skye and mull must have been, like these vast mountain-chains of the continent, an oozy sea-floor, over which the ligneous productions of the neighboring lands, washed down by the streams, grew heavy and sank, and on which the belemnite dropped its spindle and the ammonite its shell. the idea imparted of _old_ scotland to the geologist here,--of scotland, proudly, aristocratically, supereminently old,--for it can call mont blanc a mere upstart, and dhawalageri, with its twenty-eight thousand feet of elevation, a heady fellow of yesterday,--is not that of a land settling down by the head, like a foundering vessel, but of a land whose hills and islands, like its great aristocratic families, have arisen from the level in very various ages, and under the operation of circumstances essentially diverse. we left behind us the islands of lunga, luing, and seil, and entered the narrow sound of kerrera, with its border of old red conglomerate resting on the clay-slate of the district. we had passed esdaile near enough to see the workmen employed in the quarries of the island, so extensively known in commerce for their roofing slate, and several small vessels beside them, engaged in loading; and now we had got a step higher in the geological scale, and could mark from the deck the peculiar character of the conglomerate, which, in cliffs washed by the sea, when the binding matrix is softer than the pebbles which it encloses, roughens, instead of being polished, by the action of the waves, and which, along the eastern side of the sound here, seems as if formed of cannon-shot, of all sizes, embedded in cement. the sound terminates in the beautiful bay of oban, so quiet and sheltered, with its two island breakwaters in front,--its semi-circular sweep of hill behind,--its long white-walled village, bent like a bow, to conform to the inflection of the shore,--its mural precipices behind, tapestried with ivy,--its rich patches of green pasture,--its bosky dingles of shrub and tree,--and, perched on the seaward promontory, its old, time-eaten keep. "in one part of the harbor of oban," says dr. james anderson, in his "practical treatise on peat moss," ( ), "where the depth of the sea is about twenty fathoms, the bottom is found to consist of quick peat, which affords no safe anchorage." i made inquiry at the captain of the steamer, regarding this submerged deposit, but he had never heard of it. there are, however, many such on the coasts of both britain and ireland. we staid at oban for several hours, waiting the arrival of the fort william steamer; and, taking out hammer and chisel from my bag, i stepped ashore to question my ancient acquaintance, the old red conglomerate, and was fortunate enough to meet on the pier-head, as i landed, one of the best of companions for assisting in such work, mr. colin elder, of isle ornsay,--the gentleman who had so kindly furnished my friend mr. swanson with an asylum for his family, when there was no longer a home for them in small isles. "you are much in luck," he said, after our first greeting: "one of the villagers, in improving his garden, has just made a cut for some fifteen or twenty yards along the face of the precipice behind the village, and laid open the line of junction between the conglomerate and the clay-slate. let us go and see it." i found several things worthy of notice in the chance section to which i was thus introduced. the conglomerate lies uncomfortably along the edges of the slate strata, which present under it an appearance exactly similar to that which they exhibit under the rolled stones and shingle of the neighboring shore, where we find them laid bare beside the harbor, for several hundred yards. and, mixed with the pebbles of various character and origin of which the conglomerate is mainly composed, we see detached masses of the slate, that still exhibit on their edges the identical lines of fracture characteristic of the rock, which they received, when torn from the mass below, myriads of ages before. in the incalculably remote period in which the conglomerate base of the old red sandstone was formed, the clay-slate of this district had been exactly the same sort of rock that it is now. some long anterior convulsion had upturned its strata, and the sweep of water, mingled with broken fragments of stone, had worn smooth the exposed edges, just as a similar agency wears the edges exposed at the present time. quarries might have been opened in this rock, as now, for a roofing-slate, had there been quarriers to open them, or houses to roof over; it was in every respect as ancient a looking stone then as in the present late age of the world. there are no sermons that seem stranger or more impressive to one who has acquired just a little of the language in which they are preached, than those which, according to the poet, are to be found in stones; a bit of fractured slate, embedded among a mass of rounded pebbles, proves voluble with ideas of a kind almost too large for the mind of man to grasp. the eternity that hath passed is an ocean without a further shore, and a finite conception may in vain attempt to span it over. but from the beach, strewed with wrecks, on which we stand to contemplate it, we see far out towards the cloudy horizon, many a dim islet and many a pinnacled rock, the sepulchres of successive eras,--the monuments of consecutive creations: the entire prospect is studded over with these landmarks of a hoar antiquity, which, measuring out space from space, constitute the vast whole a province of time; nor can the eye reach to the open, shoreless infinitude beyond, in which only god existed; and, as in a sea-scene in nature, in which headland stretches dim and blue beyond headland, and islet beyond islet, the distance seems not lessened, but increased, by the crowded objects--we borrow a larger, not a smaller idea of the distant eternity, from the vastness of the measured periods that occur between. over the lower bed of conglomerate, which here, as on the east coast, is of great thickness, we find a bed of gray stratified clay, containing a few calcareo-argillaceous nodules. the conglomerate cliffs to the north of the village present appearances highly interesting to the geologist. rising in a long wall within the pleasure-grounds of dunolly castle, we find them wooded atop and at the base; while immediately at their feet there stretches out a grassy lawn, traversed by the road from the village to the castle, which sinks with a gradual slope into the existing sea-beach, but which ages ago must have been a sea-beach itself. we see the bases of the precipices hollowed and worn, with all their rents and crevices widened into caves; and mark, at a picturesque angle of the rock, what must have been once an insulated sea-stack, some thirty or forty feet in height, standing up from amid the rank grass, as at one time it stood up from amid the waves. tufts of fern and sprays of ivy bristle from its sides, once roughened by the serrated kelp-weed and the tangle. the highlanders call it m'dougal's dog-stone, and say that the old chieftains of lorne made use of it as a post to which to fasten their dogs,--animals wild and gigantic as themselves,--when the hunters were gathering to rendezvous, and the impatient beagles struggled to break away and begin the chase on their own behalf. it owes its existence as a stack--for the precipice in which it was once included has receded from around it for yards--to an immense boulder in its base--by far the largest stone i ever saw in an old red conglomerate. the mass is of a rudely rhomboidal form, and measures nearly twelve feet in the line of its largest diagonal. a second huge pebble in the same detached spire measures four feet by about three. both have their edges much rounded, as if, ere their deposition in the conglomerate, they had been long exposed to the wear of the sea; and both are composed of an earthy amygdaloidal trap. i have stated elsewhere ["old red sandstone," chapter xii.], that i had scarce ever seen a stone in the old red conglomerate which i could not raise from the ground; and ere i said so i had examined no inconsiderable extent of this deposit, chiefly, however, along the eastern coast of scotland, where its larger pebbles rarely exceed two hundred weight. how account for the occurrence of pebbles of so gigantic a size here? we can but guess at a solution, and that very vaguely. the islands of mull and kerrera form, in the present state of things, inner and outer breakwaters between what is now the coast of oban and the waves of the atlantic; but mull, in the times of even the oölite, must have existed as a mere sea-bottom; and kerrera, composed mainly of trap, which has brought with it to the surface patches of the conglomerate, must, when the conglomerate was in forming, have been a mere sea-bottom also. is it not possible, that when the breakwaters _were not_, the atlantic _was_, and that its tempests, which in the present time can transport vast rocks for hundreds of yards along the exposed coasts of shetland and orkney, may have been the agent here in the transport of these huge pebbles of the old red conglomerate? "rocks that two or three men could not lift," say the messrs. anderson of inverness, in describing the storms of orkney, "are washed about even on the tops of cliffs, which are between sixty and a hundred feet above the surface of the sea, when smooth; and detached masses of rock, of an enormous size, are well known to have been carried a considerable distance between low and high-water mark." "a little way from the brough," says dr. patrick neill, in his 'tour through orkney and shetland,' "we saw the prodigious effects of a late winter storm: many great stones, one of them of several tons weight, had been tossed up a precipice twenty or thirty feet high, and laid fairly on the green sward." there is something farther worthy of notice in the stone of which the two boulders of the dog-stack are composed. no species of rock occurs more abundantly in the embedded pebbles of this ancient conglomerate than rocks of the trap family. we find in it trap-porphyries, greenstones, clinkstones, basalts, and amygdalolds, largely mingled with fragments of the granitic, clay-slate, and quartz rocks. the plutonic agencies must have been active in the locality for periods amazingly protracted; and many of the masses protruded at a very early time seem identical in their composition with rocks of the trap family, which in other parts of the country we find referred to much later eras. there occur in this deposit rolled pebbles of a basalt, which in the neighborhood of edinburgh would be deemed considerably more modern than the times of the mountain limestone, and in the isle of skye, considerably more modern than the times of the oölite. the sunlight was showering its last slant rays on island and loch, and then retreating upwards along the higher hills, chased by the shadows, as our boat quitted the bay of oban, and stretched northwards, along the end of green lismore, for the sound of mull. we had just enough of day left, as we reached mid sea, to show us the gray fronts of the three ancient castles,--- which at this point may be at once seen from the deck,--dunolly, duart, and dunstaffnage; and enough left us as we entered the sound, to show, and barely show, the lady rock, famous in tradition, and made classic by the pen of campbell, raising its black back amid the tides, like a belated porpoise. and then twilight deepened into night, and we went snorting through the strait with a stream of green light curling off from either bow in the calm, towards the high dim land, that seemed standing up on both sides like tall hedges over a green lane. we entered the bay of tobermory about midnight, and cast anchor amid a group of little vessels. an exceedingly small boat shot out from the side of a yacht of rather diminutive proportions, but tautly rigged for her size, and bearing an outrigger astern. the water this evening was full of phosphoric matter, and it gleamed and sparkled around the little boat like a northern aurora around a dark cloudlet. there was just light enough to show that the oars were plied by a sailor-like man in a guernsey frock, and that another sailor-like man,--the skipper, mayhap,--attired in a cap and pea-jacket, stood in the stern. the man in the guernsey frock was john stewart, sole mate and half the crew of the free church yacht betsey; and the skipper-like man in the pea-jacket was my friend the minister of the protestants of small isles. in five minutes more i was sitting with mr. elder beside the little iron stove in the cabin of the betsey; and the minister, divested of his cap and jacket, but still looking the veritable skipper to admiration, was busied in making us a rather late tea. the cabin,--my home for the greater part of the three following weeks, and that of my friend for the greater part of the previous twelvemonth,--i found to be an apartment about twice the size of a common bed, and just lofty enough under the beams to permit a man of five feet eleven to stand erect in his night-cap. a large table, lashed to the floor, furnished with tiers of drawers of all sorts and sizes, and bearing a writing desk bound to it a-top, occupied the middle space, leaving just room enough for a person to pass between its edges and the narrow coffin-like beds in the sides, and space enough at its fore-end for two seats in front of the stove. a jealously barred skylight opened above; and there depended from it this evening a close lantern-looking lamp, sufficiently valuable, no doubt, in foul weather, but dreary and dim on the occasions when all one really wished from it was light. the peculiar furniture of the place gave evidence to the mixed nature of my friend's employment. a well-thumbed chart of the western islands lay across an equally well-thumbed volume of henry's "commentary." there was a polyglot and a spy-glass in one corner, and a copy of calvin's "institutes," with the latest edition of "the coaster's sailing directions," in another; while in an adjoining state-room, nearly large enough to accommodate an arm-chair, if the chair could have but contrived to get into it, i caught a glimpse of my friend's printing press and his case of types, canopied overhead by the blue ancient of the vessel, bearing, in stately six-inch letters of white bunting, the legend, "free church yacht." a door opened, which communicated with the forecastle, and john stewart, stooping very much, to accommodate himself to the low-roofed passage, thrust in a plate of fresh herrings, splendidly toasted, to give substantiality and relish to our tea. the little rude forecastle, a considerably smaller apartment than the cabin, was all a-glow with the bright fire in the coppers, itself invisible; we could see the chain-cable dangling from the hatchway to the floor, and john stewart's companion, a powerful-looking, handsome young man, with broad bare breast, and in his shirt-sleeves, squatted full in front of the blaze, like the household goblin described by milton, or the "christmas present" of dickens. mr. elder left us for the steamer, in which he prosecuted his voyage next morning to skye; and we tumbled in, each to his narrow bed,--comfortable enough sort of resting places, though not over soft; and slept so soundly, that we failed to mark mr. elder's return for a few seconds, a little after daybreak. i found at my bedside, when i awoke, a fragment of rock which he had brought from the shore, charged with liasic fossils; and a note he had written, to say that the deposit to which it belonged occurred in the trap immediately above the village-mill; and further, to call my attention to a house near the middle of the village, built of a mouldering red sandstone, which had been found _in situ_ in digging the foundations. i had but little time for the work of exploration in mull, and the information thus kindly rendered enabled me to economize it. the village of tobermory resembles that of oban. a quiet bay has its secure island-breakwater in front; a line of tall, well-built houses, not in the least rural in their aspect, but that seem rather as if they had been transported from the centre of some stately city entire and at once, sweeps round its inner inflection, like a bent bow; and an amphitheatre of mingled rock and wood rises behind. with all its beauty, however, there hangs about the village an air of melancholy. like some of the other western coast villages, it seems not to have grown, piece-meal, as a village ought, but to have been made wholesale, as frankenstein made his man; and to be ever asking, and never more incessantly than when it is at its quietest, why it should have been made at all? the remains of the florida, a gallant spanish ship, lie off its shores, a wreck of the invincible armada, "deep whelmed," according to thompson, "what time, snatched sudden by the vengeful blast, the scattered vessels drove, and on blind shelve, and pointed rock that marks th' indented shore, relentless dashed, where loud the northern main howls through the fractured caledonian isles." macculloch relates, that there was an attempt made, rather more than a century ago, to weigh up the florida, which ended in the weighing up of merely a few of her guns, some of them of iron greatly corroded; and that, on scraping them, they became so hot under the hand that they could not be touched, but that they lost this curious property after a few hours' exposure to the air. there have since been repeated instances elsewhere, he adds, of the same phenomenon, and chemistry has lent its solution of the principles on which it occurs; but, in the year , ere the riddle was read, it must have been deemed a thoroughly magical one by the simple islanders of mull. it would seem as if the guns, heated in the contest with drake, hawkins, and frobisher, had again kindled, under some supernatural influence, with the intense glow of the lost battle. the morning was showery; but it cleared up a little after ten, and we landed to explore. we found the mill a little to the south of the village, where a small stream descends, all foam and uproar, from the higher grounds along a rocky channel half-hidden by brushwood; and the liasic bed occurs in an exposed front directly over it, coped by a thick bed of amygdaloidal trap. the organisms are numerous; and, when we dig into the bank beyond the reach of the weathering influences, we find them delicately preserved, though after a fashion that renders difficult their safe removal. originally the bed must have existed as a brown argillaceous mud, somewhat resembling that which forms in the course of years, under a scalp of muscles; and it has hardened into a more silt-like clay, in which the fossils occur, not as petrifactions, but as shells in a state of decay, except in some rare cases, in which a calcareous nodule has formed within or around them. viewed in the group, they seem of an intermediate character, between the shells of the lias and the oölite. one of the first fossils i disinterred was the gryphæa obliquata,--a shell characteristic of the liasic formation; and the fossil immediately after, the pholadomy æqualis, a shell of the oölitic one. there occurs in great numbers a species of small pecten,--some of the specimens scarce larger than a herring scale; a minute ostrea, a sulcated terebratula, an isocardia, a pullastra, and groups of broken serpulæ in vast abundance. the deposit has also its three species of ammonite, existing as mere impressions in the clay; and at least two species of belemnite,--one of the two somewhat resembling the belemnites abbreviatus, but smaller and rather more elongated: while the other, of a spindle form, diminishing at both ends, reminds one of the belemnites minimus of the gault. the red sandstone in the centre of the village occurs detached, like this liasic bed, amid the prevailing trap, and may be seen _in situ_ beside the southern gable of the tall, deserted looking house at the hill-foot, that has been built of it. it is a soft, coarse-grained, mouldering stone, ill fitted for the purposes of the architect; and more nearly resembles the new red sandstone of england and dumfriesshire, than any other rock i have yet seen in the north of scotland. i failed to detect in it aught organic. we weighed anchor about two o'clock, and beat gallantly out the sound, in the face of an intermittent baffling wind and a heavy swell from the sea. i would fain have approached nearer the precipices of ardnamurchan, to trace along their inaccessible fronts the strange reticulations of trap figured by macculloch; but prudence and the skipper forbade our trusting even the docile little betsey, on one of the most formidable lee shores in scotland, in winds so light and variable, and with the swell so high. we could hear the deep roar of the surf for miles, and see its undulating strip of white flickering under stack and cliff. the scenery here seems rich in legendary association. at one tack we bore into bloody bay, on the mull coast,--the scene of a naval battle between two island chiefs; at another, we approached, on the mainland, a cave inaccessible save from the sea, long the haunt of a ruthless highland pirate. ere we rounded the headland of ardnamurchan, the slant light of evening was gleaming athwart the green acclivities of mull, barring them with long horizontal lines of shadow, where the trap terraces rise step beyond step, in the characteristic stair-like arrangement to which the rock owes its name; and the sun set as we were bearing down in one long tack on the small isles. we passed the isle of muck, with its one low hill; saw the pyramidal mountains of rum looming tall in the offing; and then, running along the isle of eigg, with its colossal scuir rising between us and the sky, as if it were a piece of babylonian wall, or of the great wall of china, only vastly larger, set down on the ridge of a mountain, we entered the channel which separates the island from one of its dependencies, eilean chaisteil, and cast anchor in the tideway, about fifty yards from the rocks. we were now at home,--the only home which the proprietor of the island permits to the islanders' minister; and, after getting warm and comfortable over the stove and a cup of tea, we did what all sensible men do in their own homes when the night wears late,--got into bed. chapter ii. the minister's larder--no harbor--eigg shoes--_tormentilla erecta_--for the _witness'_ sake--eilean chaisteil--appearance of eigg--chapel of st. donan--shell-sand--origin of secondary calcareous rock suggested--exploration of eigg--pitchstone veins--a bone cave--massacre at eigg--grouping of human bones in the cave--relics--the horse's tooth--a copper sewing needle--teeth found--man a worse animal than his teeth show him to have been designed for--story of the massacre--another version--scuir of eigg--the scuir a giant's causeway--character of the columns--remains of a prostrate forest. we had rich tea this morning. the minister was among his people; and our first evidence of the fact came in the agreeable form of three bottles of fine fresh cream from the shore. then followed an ample baking of nice oaten cakes. the material out of which the cakes were manufactured had been sent from the minister's store aboard,--for oatmeal in eigg is rather a scarce commodity in the middle of july; but they had borrowed a crispness and flavor from the island, that the meal, left to its own resources, could scarcely have communicated; and the golden-colored cylinder of fresh butter which accompanied them was all the island's own. there was an ample supply of eggs too, as one not quite a conjuror might have expected from a country bearing such a name,--eggs with the milk in them; and, with cream, butter, oaten cakes, eggs, and tea, all of the best, and with sharp-set sea-air appetites to boot, we fared sumptuously. there is properly no harbor in the island. we lay in a narrow channel, through which, twice every twenty-four hours, the tides sweep powerfully in one direction, and then as powerfully in the direction opposite; and our anchors had a trick of getting foul, and canting stock downwards in the loose sand, which, with pointed rocks all around us, over which the current ran races, seemed a very shrewd sort of trick indeed. but a kedge and halser, stretched thwartwise to a neighboring crag, and jammed fast in a crevice, served in moderate weather to keep us tolerably right. in the severer seasons, however, the kedge is found inadequate, and the minister has to hoist sail and make out for the open sea, as if served with a sudden summons of ejectment. among the various things brought aboard this morning, there was a pair of island shoes for the minister's cabin use, that struck my fancy not a little. they were all around of a deep madder red color, soles, welts and uppers; and, though somewhat resembling in form the little yawl of the betsey, were sewed not unskilfully with thongs; and their peculiar style of tie seemed of a kind suited to furnish with new idea a fashionable shoemaker of the metropolis. they were altogether the production of eigg, from the skin out of which they had been cut, with the lime that had prepared it for the tan, and the root by which the tan had been furnished, down to the last on which they had been moulded, and the artisan that had cast them off, a pair of finished shoes. there are few trees, and, of course, no bark to spare, in the island; but the islanders find a substitute in the astringent lobiferous root of the _tormentilla erecta_, which they dig out for the purpose among the heath, at no inconsiderable expense of time and trouble. i was informed by john stewart, an adept in all the multifarious arts of the island, from the tanning of leather and the tilling of land, to the building of a house or the working of a ship, that the infusion of root had to be thrice changed for every skin, and that it took a man nearly a day to gather roots enough for a single infusion. i was further informed that it was not unusual for the owner of a skin to give it to some neighbor to tan, and that, the process finished, it was divided equally between them, the time and trouble bestowed on it by the one being deemed equivalent to the property held in it by the other. i wished to call a pair of these primitive-looking shoes my own, and no sooner was the wish expressed, than straightway one islander furnished me with leather, and another set to work upon the shoes. when i came to speak of remuneration, however, the islanders shook their heads. "no, no, not from the _witness_: there are not many that take our part, and the _witness_ does." i hold the shoes, therefore, as my first retainer, determined, on all occasions of just quarrel, to make common cause with the poor islanders. the view from the anchoring ground presents some very striking features. between us and the sea lies eilean chaisteil, a rocky trap islet, about half a mile in length by a few hundred yards in breadth; poor in pastures, but peculiarly rich in sea-weed, of which john stewart used, he informed me, to make finer kelp, ere the trade was put down by act of parliament, than could be made elsewhere in eigg. this islet bore, in the remote past, its rude fort or dun, long since sunk into a few grassy mounds; and hence its name. on the landward side rises the island of eigg proper, resembling in outline two wedges, placed point to point on a board. the centre is occupied by a deep angular gap, from which the ground slopes upward on both sides, till, attaining its extreme height at the opposite ends of the island, it drops suddenly on the sea. in the northern rising ground the wedge-like outline is complete; in the southern one it is somewhat modified by the gigantic scuir, which rises direct on the apex of the height, _i.e._, the thick part of the wedge; and which, seen bows-on from this point of view, resembles some vast donjon keep, taller, from base to summit, by about a hundred feet, than the dome of st. paul's. the upper slopes of the island are brown and moory, and present little on which the eye may rest, save a few trap terraces, with rudely columnar fronts; its middle space is mottled with patches of green, and studded with dingy cottages, each of which this morning, just a little before the breakfast hour, had its own blue cloudlet of smoke diffused around it; while along the beach, patches of level sand, alternated with tracts of green bank, or both, give place to stately ranges of basaltic columns, or dingy groups of detached rocks. immediately in front of the central hollow, as if skilfully introduced, to relieve the tamest part of the prospect, a noble wall of semi-circular columns rises some eighty or a hundred feet over the shore; and on a green slope, directly above, we see the picturesque ruins of the chapel of st. donan, one of the disciples of columba, and the culdee saint and apostle of the island. one of the things that first struck me, as i got on deck this morning, was the extreme whiteness of the sand. i could see it gleaming bright through the transparent green of the sea, three fathoms below our keel, and, in a little flat bay directly opposite, it presented almost the appearance of pulverized chalk. a stronger contrast to the dingy trap-rocks around which it lies could scarce be produced, had contrast for effect's sake been the object. on landing on the exposed shelf to which we had fastened our halser, i found the origin of the sand interestingly exhibited. the hollows of the rock, a rough trachyte, with a surface like that of a steel rasp, were filled with handfuls of broken shells thrown up by the surf from the sea-banks beyond: fragments of echini, bits of the valves of razor-fish, the island cyprina, mactridæ, buccinidæ, and fractured periwinkles, lay heaped together in vast abundance. in hollow after hollow, as i passed shorewards, i found the fragments more and more comminuted, just as, in passing along the successive vats of a paper-mill, one finds the linen rags more and more disintegrated by the cylinders; and immediately beyond the inner edge of the shelf, which is of considerable extent, lies the flat bay, the ultimate recipient of the whole, filled to the depth of several feet, and to the extent of several hundred yards, with a pure shell-sand, the greater part of which had been thus washed ashore in handfuls, and ground down by the blended agency of the trachyte and the surf. once formed, however, in this way it began to receive accessions from the exuviæ of animals that love such localities,--the deep arenaceous bed and soft sand-beach; and these now form no inconsiderable proportion of the entire mass. i found the deposit thickly inhabited by spatangi, razor-fish, gapers, and large, well-conditioned cockles, which seemed to have no idea whatever that they were living amid the debris of a charnel house. such has been the origin here of a bed of shell-sand, consisting of many thousand tons, and of which at least eighty per cent. was once associated with animal life. and such, i doubt not, is the history of many a calcareous rock in the later secondary formations. there are strata, not a few, of the cretaceous and oölitic groups, that would be found--could we but trace their beginnings with a certainty and clearness equal to that with which we can unravel the story of this deposit--to be, like it, elaborations from dead matter, made through the agency of animal secretion. we set out on our first exploratory ramble in eigg an hour before noon. the day was bracing and breezy, and a clear sun looked cheerily down on island, and strait, and blue open sea. we rowed southwards in our little boat, through the channel of eilean chaisteil, along the trap-rocks of the island, and landed under the two pitchstone veins of eigg, so generally known among mineralogists, and of which specimens may be found in so many cabinets. they occur in an earthy, greenish-black amygdaloid, which forms a range of sea-cliffs varying in height from thirty to fifty feet, and that, from their sad hue and dull fracture, seem to absorb the light; while the veins themselves, bright and glistening, glitter in the sun, as if they were streams of water traversing the face of the rock. the first impression they imparted, in viewing them from the boat, was, that the inclosing mass was a pitch caldron, rather of the roughest and largest, and much begrimmed by soot, that had cracked to the heat, and that the fluid pitch was forcing its way outwards through the rents. the veins expand and contract, here diminishing to a strip a few inches across, there widening into a comparatively broad belt, some two or three feet over; and, as well described by m'culloch, we find the inclosed pitchstone changing in color, and assuming a lighter or darker hue, as it nears the edge or recedes from it. in the centre it is of a dull olive green, passing gradually into blue, which in turn deepens into black; and it is exactly at the point of contact with the earthy amygdaloid that the black is most intense, and the fracture of the stone glassiest and brightest. i was lucky enough to detach a specimen, which, though scarce four inches across, exhibits the three colors characteristic of the vein,--its bar of olive green on the one side, of intense black on the other, and of blue, like that of imperfectly fused bottle-glass, in the centre. this curious rock,--so nearly akin in composition and appearance to obsidian,--a mineral which, in its dense form, closely resembles the coarse dark-colored glass of which common bottles are made, and which, in its lighter form, exists as pumice,--constitutes one of the links that connect the trap with the unequivocally volcanic rocks. the one mineral may be seen beside smoking crater, as in the lipari isles, passing into pumice; while the other may be converted into a substance almost identical with pumice, by the chemist. "it is stated by the honorable george knox, of dublin," says mr. robert allan, in his valuable mineralogical work, "that the pitchstone of newry, on being exposed to a high temperature, loses its bitumen and water, and is converted into a light substance in every respect resembling pumice." but of pumice in connection with the pitchstones of eigg, more anon. leaving our boat to return to the betsey at john stewart's leisure, and taking with us his companion, to assist us in carrying such specimens as we might procure, we passed westwards for a few hundred yards under the crags, and came abreast of a dark angular opening at the base of the precipice, scarce two feet in height, and in front of which there lies a little sluggish, ankle-deep pool, half mud, half water, and matted over with grass and rushes. along the mural face of the rock of earthy amygdaloid there runs a nearly vertical line, which in one of the stratified rocks one might perhaps term the line of a fault, but which in a trap rock may merely indicate where two semi-molten masses had pressed against each other without uniting--just as currents of cooling lead, poured by the plumber from the opposite end of a groove, sometimes meet and press together, so as to make a close, polished joint, without running into one piece. the little angular opening forms the lower termination of the line, which, hollowing inwards, recedes near the bottom into a shallow cave, roughened with tufts of fern and bunches of long silky grass, here and there enlivened by the delicate flowers of the lesser rock-geranium. a shower of drops patters from above among the weeds and rushes of the little pool. my friend the minister stopped short. "there," he said, pointing to the hollow, "you will find such a bone cave as you never saw before. within that opening there lie the remains of an entire race, palpably destroyed, as geologists in so many other cases are content merely to imagine, by one great catastrophe. that is the famous cave of frances (_uamh fraingh_), in which the whole people of eigg were smoked to death by the m'leods." we struck a light, and, worming ourselves through the narrow entrance, gained the interior,--a true rock gallery, vastly more roomy and lofty than one could have anticipated from the mean vestibule placed in front of it. its extreme length we found to be two hundred and sixty feet; its extreme breadth twenty-seven feet; its height, where the roof rises highest, from eighteen to twenty feet. the cave seems to have owed its origin to two distinct causes. the trap-rocks on each side of the vertical fault-like crevice which separates them are greatly decomposed, as if by the moisture percolating from above; and directly in the line of the crevice must the surf have charged, wave after wave, for ages ere the last upheaval of the land. when the dog-stone at dunolly existed as a sea-stack, skirted with algæ, the breakers on this shore must have dashed every tide through the narrow opening of the cavern, and scooped out by handfuls the decomposing trap within. the process of decomposition, and consequent enlargement, is still going on inside, but there is no longer an agent to sweep away the disintegrated fragments. where the roof rises highest, the floor is blocked up with accumulations of bulky decaying masses, that have dropped from above; and it is covered over its entire area by a stratum of earthy rubbish, which has fallen from the sides and ceiling in such abundance, that it covers up the straw beds of the perished islanders, which still exist beneath as a brown mouldering felt, to the depth of from five to eight inches. never yet was tragedy enacted on a gloomier theatre. an uncertain twilight glimmers gray at the entrance, from the narrow vestibule; but all within, for full two hundred feet, is black as with egyptian darkness. as we passed onward with our one feeble light, along the dark mouldering walls and roof, which absorbed every straggling ray that reached them, and over the dingy floor, ropy and damp, the place called to recollection that hall in roman story, hung and carpeted with black, into which domitian once thrust his senate, in a frolic, to read their own names on the coffin-lids placed against the wall. the darkness seemed to press upon us from every side, as if it were a dense jetty fluid, out of which our light had scooped a pailful or two, and that was rushing in to supply the vacuum; and the only objects we saw distinctly visible were each other's heads and faces, and the lighter parts of our dress. the floor, for about a hundred feet inwards from the narrow vestibule, resembles that of a charnel-house. at almost every step we came upon heaps of human bones grouped together, as the psalmist so graphically describes, "as when one cutteth and cleaveth wood upon the earth." they are of a brownish, earthy hue, here and there tinged with green; the skulls, with the exception of a few broken fragments, have disappeared; for travellers in the hebrides have of late years been numerous and curious; and many a museum,--that at abbotsford among the rest,--exhibits, in a grinning skull, its memorial of the massacre at eigg. we find, too, further marks of visitors in the single bones separated from the heaps and scattered over the area; but enough still remains to show, in the general disposition of the remains, that the hapless islanders died under the walls in families, each little group separated by a few feet from the others. here and there the remains of a detached skeleton may be seen, as if some robust islander, restless in his agony, had stalked out into the middle space ere he fell; but the social arrangement is the general one. and beneath every heap we find, at the depth, as has been said, of a few inches, the remains of the straw-bed upon which the family had lain, largely mixed with the smaller bones of the human frame, ribs and vertebræ, and hand and feet bones; occasionally, too, with fragments of unglazed pottery, and various other implements of a rude housewifery. the minister found for me, under one family heap, the pieces of a half-burned, unglazed earthen jar, with a narrow mouth, that, like the sepulchral urns of our ancient tumuli, had been moulded by the hand, without the assistance of the potter's wheel; and to one of the fragments there stuck a minute pellet of gray hair. from under another heap he disinterred the handle-stave of a child's wooden porringer (_bicker_), perforated by a hole still bearing the mark of the cord that had hung it to the wall; and beside the stave lay a few of the larger, less destructible bones of the child, with what for a time puzzled us both not a little,--one of the grinders of a horse. certain it was, no horse could have got there to have dropped a tooth,--a foal of a week old could not have pressed itself through the opening; and how the single grinder, evidently no recent introduction into the cave, could have got mixed up in the straw with the human bones, seemed an enigma somewhat of the class to which the reel in the bottle belongs. i found in edinburgh an unexpected commentator on the mystery, in the person of my little boy,--an experimental philosopher in his second year. i had spread out on the floor the curiosities of eigg,--among the rest, the relics of the cave, including the pieces of earthern jar, and the fragment of the porringer; but the horse's tooth seemed to be the only real curiosity among them in the eyes of little bill. he laid instant hold of it; and, appropriating it as a toy, continued playing with it till he fell asleep. i have now little doubt that it was first brought into the cave by the poor child amid whose mouldering remains mr. swanson found it. the little pellet of gray hair spoke of feeble old age involved in this wholesale massacre with the vigorous manhood of the island; and here was a story of unsuspecting infancy amusing itself on the eve of destruction with its toys. alas, for man! "should not i spare nineveh, that great city," said god to the angry prophet, "wherein are more than six score thousand persons that cannot discern between their right hand and their left?" god's image must have been sadly defaced in the murderers of the poor inoffensive children of eigg, ere they could have heard their feeble wailings, raised, no doubt, when the stifling atmosphere within began first to thicken, and yet ruthlessly persist in their work of indiscriminate destruction. various curious things have from time to time been picked up from under the bones. an islander found among them, shortly before our visit, a sewing needle of copper, little more than an inch in length; fragments of eigg shoes, of the kind still made in the island, are of comparatively common occurrence; and mr. james wilson relates, in the singularly graphic and powerful description of _uamh fraingh_, which occurs in his "voyage round the coasts of scotland" ( ), that a sailor, when he was there, disinterred, by turning up a flat stone, a "buck-tooth" and a piece of money,--the latter a rusty copper coin, apparently of the times of mary of scotland. i also found a few teeth; they were sticking fast in a fragment of jaw; and, taking it for granted, as i suppose i may, that the dentology of the murderous m'leods outside the cave must have very much resembled that of the murdered m'donalds within, very harmless looking teeth they were for being those of an animal so maliciously mischievous as man. i have found in the old red sandstone the strong-based tusks of the semi-reptile holoptychius; i have chiselled out of the limestone of the coal measures the sharp, dagger-like incisors of the megalichthys; i have picked up in the lias and oölite the cruel spikes of the crocodile and the ichthyosaurus; i have seen the trenchant, saw-edged teeth of gigantic cestracions and squalidæ that had been disinterred from the chalk and the london clay; and i have felt, as i examined them, that there could be no possibility of mistake regarding the nature of the creatures to which they had belonged;--they were teeth made for hacking, tearing, mangling,--for amputating limbs at a bite, and laying open bulky bodies with a crunch; but i could find no such evidence in the human jaw, with its three inoffensive looking grinders, that the animal it had belonged to,--far more ruthless and cruel than reptile-fish, crocodiles, or sharks,--was of such a nature that it could destroy creatures of even its own kind by hundreds at a time, when not in the least incited by hunger, and with no ultimate intention of eating them. man must surely have become an immensely worse animal than his teeth show him to have been designed for; his teeth give no real evidence regarding his real character. who, for instance, could gather from the dentology of the m'leods the passage in their history to which the cave of frances bears evidence? we quitted the cave, with its stagnant damp atmosphere and its mouldy unwholesome smells, to breathe the fresh sea-air on the beach without. its story, as recorded by sir walter in his "tales of a grandfather," and by mr. wilson, in his "voyage," must be familiar to the reader; and i learned from my friend, versant in all the various island traditions regarding it, that the less i inquired into its history on the spot, the more was i likely to feel satisfied that i knew something about it. there seem to have been no chroniclers, in this part of the hebrides, in the rude age of the unglazed pipkin and the copper needle; and many years seem to have elapsed ere the story of their hapless possessors was committed to writing; and so we find it existing in various and somewhat conflicting editions. "some hundred years ago," says mr. wilson, "a few of the m'leods landed in eigg from skye, where, having greatly misconducted themselves, the eiggites strapped them to their own boats, which they sent adrift into the ocean. they were, however, rescued by some clansmen; and, soon after, a strong body of the m'leods set sail from skye, to revenge themselves on eigg. the natives of the latter island feeling they were not of sufficient force to offer resistance, went and hid themselves (men, women, and children) in this secret cave, which is narrow, but of great subterranean length, with an exceedingly small entrance. it opens from the broken face of a steep bank along the shore; and, as the whole coast is cavernous, their particular retreat would have been sought for in vain by strangers. so the skye-men, finding the island uninhabited, presumed the natives had fled, and satisfied their revengeful feelings by ransacking and pillaging the empty houses. probably the _movables_ were of no great value. they then took their departure and left the island, when the sight of a solitary human being among the cliffs awakened their suspicion, and induced them to return. unfortunately a slight sprinkling of snow had fallen, and the footsteps of an individual were traced to the mouth of the cave. not having been there ourselves at the period alluded to, we cannot speak with certainty as to the nature of the parley which ensued, or the terms offered by either party; but we know that those were not the days of protocols. the ultimatum was unsatisfactory to the skye-men, who immediately proceeded to 'adjust the preliminaries' in their own way, which adjustment consisted in carrying a vast collection of heather, ferns, and other combustibles, and making a huge fire just in the very entrance of the _uamh fraingh_, which they kept up for a length of time; and thus, by 'one fell smoke,' they smothered the entire population of the island." such is mr. wilson's version of the story, which, in all its leading circumstances, agrees with that of sir walter. according, however, to at least one of the eigg versions, it was the m'leod himself who had landed on the island, driven there by a storm. the islanders, at feud with the m'leod's at the time, inhospitably rose upon him, as he bivouacked on the shores of the bay of laig; and in a fray, in which his party had the worse, his back was broken, and he was forced off half dead to sea. several months after, on his partial recovery, he returned, crook-backed and infirm, to wreak his vengeance on the inhabitants, all of whom, warned of his coming by the array of his galleys in the offing, hid themselves in the cave, in which, however, they were ultimately betrayed--as narrated by sir walter and mr. wilson--by the track of some footpaths in a sprinkling of snow; and the implacable chieftain, giving orders on the discovery, to unroof the houses in the neighborhood, raised high a pile of rafters against the opening, and set it on fire. and there he stood in front of the blaze, hump-backed and grim, till the wild, hollow cry from the rock within had sunk into silence, and there lived not a single islander of eigg, man, woman, or child. the fact that their remains should have been left to moulder in the cave is proof enough, of itself, that none survived to bury the dead. i am inclined to believe, from the appearance of the place, that smoke could scarcely have been the real agent of destruction; then, as now, it would have taken a great deal of pure smoke to smother a highlander. it may be perhaps deemed more probable, that the huge fire of rafter and roof-tree piled close against the opening, and rising high over it, would draw out the oxygen within as its proper food, till at length all would be exhausted; and life would go out for want of it, like the flame of a candle under an upturned jar. sir walter refers the date of the event to some time "about the close of the sixteenth century;" and the coin of queen mary, mentioned by mr. wilson, points at a period at least not much earlier; but the exact time of its occurrence is so uncertain, that a roman catholic priest of the hebrides, in lately showing his people what a very bad thing protestantism is, instanced, as a specimen of its average morality, the affair of the cave. the _protestant_ m'leods of skye, he said, full of hatred in their hearts, had murdered, wholesale, their wretched brethren, the _protestant_ m'donalds of eigg, and sent them off to perdition before their time. quitting the beach, we ascended the breezy hill-side on our way to the scuir,--an object so often and so well described, that it might be perhaps prudent, instead of attempting one description more, to present the reader with some of the already existing ones. "the scuir of eigg," says professor jamieson, in his 'mineralogy of the western islands,' "is perfectly mural, and extends for upwards of a mile and a half, and rises to a height of several hundred feet. it is entirely columnar, and the columns rise in successive ranges, until they reach the summit, where, from their great height, they appear, when viewed from below, diminutive. staffa is an object of the greatest beauty and regularity; the pillars are as distinct as if they had been reared by the hand of art; but it has not the extent or sublimity of the scuir of eigg. the one may be compared with the greatest exertions of human power; the other is characteristic of the wildest and most inimitable works of nature." "the height of this extraordinary object is considerable," says m'culloch, dashing off his sketch with a still bolder hand; "yet its powerful effect arises rather from its peculiar form, and the commanding elevation which it occupies, than from its positive altitude. viewed in one direction, it presents a long irregular wall, crowning the summit of the highest hill, while in the other it resembles a huge tower. thus it forms no natural combination of outline with the surrounding land, and hence acquires that independence in the general landscape which increases its apparent magnitude, and produces that imposing effect which it displays. from the peculiar position of the scuir, it must also inevitably be viewed from a low station. hence it everywhere towers high above the spectator; while, like other objects on the mountain outline, its apparent dimensions are magnified, and its dark mass defined on the sky, so as to produce all the additional effects arising from strong oppositions of light and shadow. the height of this rock is sufficient in this stormy country frequently to arrest the passage of the clouds, so as to be further productive of the most brilliant effects in landscape. often they may be seen hovering on its summit, and adding ideal dimensions to the lofty face, or, when it is viewed on the extremity, conveying the impression of a tower, the height of which is such as to lie in the regions of the clouds. occasionally they sweep along the base, leaving its huge and black mass involved in additional gloom, and resembling the castle of some arabian enchanter, built on the clouds, and suspended in air." it might be perhaps deemed somewhat invidious to deal with pictures such as these in the style the connoisseur in the "vicar of wakefield" dealt with the old painting, when, seizing a brush, he daubed it over with brown varnish, and then asked the spectators whether he had not greatly improved the tone of the coloring. and yet it is just possible, that in the case of at least m'culloch's picture, the brown varnish might do no manner of harm. but a homelier sketch, traced out on almost the same leading lines, with just a little less of the aërial in it, may have nearly the same subduing effect; i have, besides, a few curious touches to lay in, which seem hitherto to have escaped observation and the pencil; and in these several circumstances must lie my apology for adding one sketch more to the sketches existing already. the scuir of eigg, then, is a veritable giant's causeway, like that on the coast of antrim, taken and magnified rather more than twenty times in height, and some five or six times in breadth, and then placed on the ridge of a hill nearly nine hundred feet high. viewed sideways, it assumes, as described by m'culloch, the form of a perpendicular but ruinous rampart, much gapped above, that runs for about a mile and a quarter along the top of a lofty sloping talus. viewed endways, it resembles a tall massy tower,--such a tower as my friend, mr. d.o. hill, would delight to draw, and give delight by drawing,--a tower three hundred feet in breadth by four hundred and seventy feet in height, perched on the apex of a pyramid, like a statue on a pedestal. this strange causeway is columnar from end to end; but the columns, from their great altitude and deficient breadth, seem mere rodded shafts in the gothic style; they rather resemble bundles of rods than well-proportioned pillars. few of them exceed eighteen inches in diameter, and many of them fall short of half a foot; but, though lost in the general mass of the scuir as independent columns, when we view it at an angle sufficiently large to take in its entire bulk, they yet impart to it that graceful linear effect which we see brought out in tasteful pencil sketches and good line engravings. we approached it this day from the shore in the direction in which the eminence it stands upon assumes the pyramidal form, and itself the tower-like outline. the acclivity is barren and stony,--a true desert foreground, like those of thebes and palmyra; and the huge square shadow of the tower stretched dark and cold athwart it. the sun shone out clearly. one half the immense bulk before us, with its delicate vertical lining, lay from top to bottom in deep shade, massive and gray; one half presented its many-sided columns to the light, here and there gleaming with tints of extreme brightness, where the pitchstones presented their glassy planes to the sun; its general outline, whether pencilled by the lighter or darker tints, stood out sharp and clear; and a stratum of white fleecy clouds floated slowly amid the delicious blue behind it. but the minuter details i must reserve for my next chapter. one fact, however, anticipated just a little out of its order, may heighten the interest of the reader. there are massive buildings,--bridges of noble span, and harbors that abut far into the waves,--founded on wooden piles; and this hugest of hill-forts we find founded on wooden piles also. it is built on what a scotch architect would perhaps term a pile-_brander_ of the _pinites eiggensis_, an ancient tree of the oölite. the gigantic scuir of eigg rests on the remains of a prostrate forest. chapter iii. structure of the scuir--a stray column--the piazza--a buried pine forest the foundation of the scuir--geological poachers in a fossil preserve--_pinites eiggensis_--its description--witham's experiments on fossil pine of eigg--rings of the pine--ascent of the scuir--appearance of the top--white pitchstone--mr. greig's discovery of pumice--a sunset scene--the manse and the yacht--the minister's story--a cottage repast--american timber drifted to the hebrides--agency of the gulf stream--the minister's sheep. as we climbed the hill-side, and the shinar-like tower before us rose higher over the horizon at each step we took, till it seemed pointing at the middle sky, we could mark peculiarities in its structure which escape notice in the distance. we found it composed of various beds, each of which would make a giant's causeway entire, piled over each other like stories in a building, and divided into columns, vertical, or nearly so, in every instance except in one bed near the base, in which the pillars incline to a side, as if losing footing under the superincumbent weight. innumerable polygonal fragments,--single stones of the building,--lie scattered over the slope, composed, like almost all the rest of the scuir, of a peculiar and very beautiful stone, unlike any other in scotland--a dark pitchstone-porphyry, which, inclosing crystals of glassy feldspar, resembles in the hand-specimen, a mass of black sealing-wax, with numerous pieces of white bugle stuck into it. some of the detached polygons are of considerable size; few of them larger and bulkier, however, than a piece of column of this characteristic porphyry, about ten feet in length by two feet in diameter, which lies a full mile away from any of the others, in the line of the old burying-ground, and distant from it only a few hundred yards. it seems to have been carried there by man: we find its bearing from the scuir lying nearly at right angles with the direction of the drift-boulders of the western coast, which are, besides, of rare occurrence in the hebrides; nor has it a single neighbor; and it seems not improbable, as a tradition of the island testifies, that it was removed thus far for the purpose of marking some place of sepulture, and that the catastrophe of the cave arrested its progress after by far the longer and rougher portion of the way had been passed. the dry-arm bones of the charnel-house in the rock may have been tugging around it when the galleys of the m'leod hove in sight. the traditional history of eigg, said my friend the minister, compared with that of some of the neighboring islands, presents a decapitated aspect: the m'leods cut it off by the neck. most of the present inhabitants can tell which of their ancestors, grandfather, or great-grandfather, or great-great-grandfather, first settled in the place, and where they came from; and, with the exception of a few vague legends about st. donan and his grave, which were preserved apparently among the people of the other small isles, the island has no early traditional history. we had now reached the scuir. there occur, intercalated with the columnar beds, a few bands of a buff-colored non-columnar trap, described by m'culloch as of a texture intermediate between a greenstone and a basalt, and which, while the pitchstone around it seems nearly indestructible, has weathered so freely as to form horizontal grooves along the face of the rock, from two to five yards in depth. one of these runs for several hundred feet along the base of the scuir, just at the top of the talus, and greatly resembles a piazza, lacking the outer pillars. it is from ten to twelve feet in height, by from fifteen to twenty in depth; the columns of the pitch stone-bed immediately above it seem perilously hanging in mid air; and along their sides there trickles, in even the driest summer weather,--for the scuir is a condenser on an immense scale--minute runnels of water, that patter ceaselessly in front of the long deep hollow, like rain from the eaves of a cottage during a thunder shower. inside, however, all is dry, and the floor is covered to the depth of several inches with the dung of sheep and cattle, that find, in this singular mountain piazza, a place of shelter. we had brought a pickaxe with us; and the dry and dusty floor, composed mainly of a gritty conglomerate, formed the scene of our labors. it is richly fossiliferous, though the organisms have no specific variety; and never, certainly, have i found the remains of former creations in a scene in which they more powerfully addressed themselves to the imagination. a stratum of peat-moss, mixed with fresh-water shells, and resting on a layer of vegetable mould, from which the stumps and roots of trees still protruded, was once found in italy, buried beneath an ancient tesselated pavement; and the whole gave curious evidence of a kind fitted to picture to the imagination a background vista of antiquity, all the more remotely ancient in aspect from the venerable age of the object in front. dry ground covered by wood, a lake, a morass, and then dry ground again, had all taken precedence, on the site of the tesselated pavement, in this instance, of an old roman villa. but what was antiquity in connection with a roman villa, to antiquity in connection with the scuir of eigg? under the old foundations of this huge wall we find the remains of a pine forest, that, long ere a single bed of the porphyry had burst from beneath, had sprung up and decayed on hill and beside stream in some nameless land,--had then been swept to the sea,--had been entombed deep at the bottom in a grit of oölite,--had been heaved up to the surface, and high over it, by volcanic agencies working from beneath,--and had finally been built upon, as moles are built upon piles, by the architect that had laid down the masonry of the gigantic scuir, in one fiery layer after another. the mountain wall of eigg, with its dizzy elevation of four hundred and seventy feet, is a wall founded on piles of pine laid crossways; and, strange as the fact may seem, one has but to dig into the floor of this deep-hewn piazza, to be convinced that at least it _is_ a fact. just at this interesting stage, however, our explorations bade fair to be interrupted. our man who carried the pickaxe had lingered behind us for a few hundred yards, in earnest conversation with an islander; and he now came up, breathless and in hot haste, to say that the islander, a roman catholic tacksman in the neighborhood, had peremptorily warned him that the scuir of eigg was the property of dr. m'pherson of aberdeen, not ours, and that the doctor would be very angry at any man who meddled with it. "that message," said my friend, laughing, but looking just a little sad through the laugh, "would scarce have been sent us when i was minister of the establishment here; but it seems allowable in the case of a poor dissenter, and is no bad specimen of the thousand little ways in which the roman catholic population of the island try to annoy me, now that they see my back to the wall." i was tickled with the idea of a fossil preserve, which coupled itself in my mind, through a trick of the associative faculty, with the idea of a great fossil act for the british empire, framed on the principles of the game-laws; and, just wondering what sort of disreputable vagabonds geological poachers would become under its deteriorating influence, i laid hold of the pickaxe and broke into the stonefast floor; and thence i succeeded in abstracting,--feloniously, i dare say, though the crime has not yet got into the statute-book--some six or eight pieces of the _pinites eiggensis_, amounting in all to about half a cubic foot of that very ancient wood--value unknown. i trust, should the case come to a serious bearing, the members of the london geological society will generously subscribe half-a-crown a-piece to assist me in feeing counsel. there are more interests than mine at stake in the affair. if i be cast and committed,--i, who have poached over only a few miserable districts in scotland,--pray, what will become of some of them,--the lyells, bucklands, murchisons and sedgwicks,--who have poached over whole continents? we were successful in procuring several good specimens of the eigg pine, at a depth, in the conglomerate, of from eight to eighteen inches. some of the upper pieces we found in contact with the decomposing trap out of which the hollow piazza above had been scooped; but the greater number, as my set of specimens abundantly testify, lay embedded in the original oölitic grit in which they had been locked up, in, i doubt not, their present fossil state, ere their upheaval, through plutonic agency, from their deep-sea bottom. the annual rings of the wood, which are quite as small as in a slow-growing baltic pine, are distinctly visible in all the better pieces i this day transferred to my bag. in one fragment i reckon sixteen rings in half an inch, and fifteen in the same space in another. the trees to which they belonged seem to have grown on some exposed hill-side, where, in the course of half a century, little more than from two or three inches were added to their diameter. the _pinites eiggensis_, or eigg pine, was first introduced to the notice of the scientific world by the late mr. witham, in whose interesting work on "the internal structure of fossil vegetables" the reader may find it figured and described. the specimen in which he studied its peculiarities "was found," he says, "at the base of the magnificent mural escarpment named the scuir of eigg,--not, however, _in situ_, but among fragments of rocks of the oölitic series." the authors of the "fossil flora," where it is also figured, describe it as differing very considerably in structure from any of the coniferæ of the coal measures. "its medullary rays," says messrs. lindley and hutton, "appear to be more numerous, and frequently are not continued through one zone of wood to another, but more generally terminate at the concentric circles. it abounds also in turpentine vessels, or lacunæ, of various sizes, the sides of which are distinctly defined." viewed through the microscope, in transparent slips, longitudinal and transverse, it presents, within the space of a few lines, objects fitted to fill the mind with wonder. we find the minutest cells, glands, fibres, of the original wood preserved uninjured. _there_ still are those medullary rays entire that communicated between the pith and the outside,--_there_ still the ring of thickened cells that indicated the yearly check which the growth received when winter came on,--_there_ the polygonal reticulations of the cross section, without a single broken mesh,--_there_, too, the elongated cells in the longitudinal one, each filled with minute glands that take the form of double circles,--_there_ also, of larger size and less regular form, the lacunæ in which the turpentine lay: every nicely organized speck, invisible to the naked eye, we find in as perfect a state of keeping in the incalculably ancient pile-work on which the gigantic scuir is founded, as in the living pines that flourish green on our hill-sides. a net-work, compared with which that of the finest lace ever worn by the fair reader would seem a net-work of cable, has preserved entire, for untold ages, the most delicate peculiarities of its pattern. there is not a mesh broken, nor a circular dot away! the experiments of mr. witham on the eigg fossil, furnish an interesting example of the light which a single, apparently simple, discovery may throw on whole departments of fact. he sliced his specimen longitudinally and across, fastened the slices on glass, ground them down till they became semi-transparent, and then, examining them under reflected light by the microscope, marked and recorded the specific peculiarities of their structure. and we now know, in consequence, that the ancient eigg pine, to which the detached fragment picked up at the base of the scuir belonged,--a pine alike different from those of the earlier carboniferous period and those which exist contemporary with ourselves,--was, some _three creations_ ago, an exceedingly common tree in the country now called scotland,--as much so, perhaps, as the scotch fir is at the present day. the fossil trees found in such abundance in the neighborhood of helmsdale that they are burnt for lime,--the fossil wood of eathie, in cromartyshire, and that of shandwick, in ross,--all belong to the _pinites eiggensis_. it seems to have been a straight and stately tree, in most instances, as in the eigg specimens, of slow growth. one of the trunks i saw near navidale measured two feet in diameter, but a full century had passed ere it attained to a bulk so considerable; and a splendid specimen in my collection, from the same locality, which measures twenty-one inches, exhibits even _more_ than a hundred annual rings. in one of my specimens, and one only, the rings are of great breadth. they differ from those of all the others in the proportion in which i have seen the annual rings of a young, vigorous fir that had sprung up in some rich, moist hollow, differ from the annual rings of trees of the same species that had grown in the shallow, hard soil of exposed hill-sides. and this one specimen furnishes curious evidence that the often-marked but little understood law, which gives us our better and worse seasons in alternate groups, various in number and uncertain in their time of recurrence, obtained as early as the age of the oölite. the rings follow each other in groups of lesser and larger breadth. one group of four rings measures an inch and a quarter across, while an adjoining group of five rings measures only five-eighth parts; and in a breadth of six inches there occur five of these alternate groups. for some four or five years together, when this pine was a living tree, the springs were late and cold, and the summers cloudy and chill, as in that group of seasons which intervened between and ; and then, for four or five years, more springs were early and summers genial, as in the after group of , and . an arrangement in nature,--first observed, as we learn from bacon, by the people of the low countries, and which has since formed the basis of meteoric tables, and of predictions and elaborate cycles of the weather,--bound together the twelvemonths of the oölitic period in alternate bundles of better and worse: vegetation throve vigorously during the summers of one group, and languished, in those of another, in a state of partial development. sending away our man shipwards, laden with a bag of fossil wood, we ascended by a steep broken ravine to the top of the scuir. the columns, as we pass on towards the west, diminish in size, and assume in many of the beds considerable variety of direction and form. in one bed they belly over with a curve, like the ribs of some wrecked vessel from which the planking has been torn away; in another they project in a straight line, like muskets planted slantways on the ground to receive a charge of cavalry; in others the inclination is inwards, like that of ranges of stakes placed in front of a sea-dyke, to break the violence of the waves; while yet in others they present, as in the eastern portion of the scuir, the common vertical direction. the ribbed appearance of every crag and cliff, imparts to the scene a peculiar character; every larger mass of light and shadow is corded with minute stripes; and the feeling experienced among the more shattered peaks, and in the more broken recesses, seems near akin to that which it is the tendency of some magnificent ruin to excite, than that which awakens amid the sublime of nature. we feel as if the pillared rocks around us were like the cyclopean walls of southern italy,--the erections of some old gigantic race passed from the earth forever. the feeling must have been experienced on former occasions, amid the innumerable pillars of the scuir; for we find m'culloch, in his description, ingeniously analyzing it. "the resemblance to architecture here is much increased," he says, "by the columnar structure, which is sufficiently distinguishable, even from a distance, and produces a strong effect of artificial regularity when seen near at hand. to this vague association in the mind of the efforts of art with the magnitude of nature, is owing much of that sublimity of character which the scuir presents. the sense of power is a fertile source of the sublime; and as the appearance of power exerted, no less than that of simplicity, is necessary to confer this character on architecture, so the mind, insensibly transferring the operations of nature to the efforts of art where they approximate in character, becomes impressed with a feeling rarely excited by her more ordinary forms, where these are even more stupendous." the top of the scuir, more especially towards its eastern termination, resembles that of some vast mole not yet levelled over by the workmen; the pavement has not yet been laid down, and there are deep gaps in the masonry, that run transversely, from side to side, still to fill up. along one of these ditch-like gaps, which serves to insulate the eastern and highest portion of the scuir from all its other portions, we find fragments of a rude wall of uncemented stones, the remains of an ancient hill-fort; which, with its natural rampart of rock on three of its four sides, more than a hundred yards in sheer descent, and with its deep ditch and rude wall on the fourth, must have formed one of the most inaccessible in the kingdom. the masses of pitchstone a-top, though so intensely black within, are weathered on the surface into almost a pure white; and we found lying detached among them, fragments of common amygdaloid and basalt, and minute slaty pieces of chalcedony that had formed apparently in fissures of the trap. we would have scrutinized more narrowly at the time had we expected to find anything more rare; but i did not know until full four months after, that aught more rare was to be found. had we examined somewhat more carefully, we might possibly have done what mr. woronzow greig did on the scuir about eighteen years previous,--picked up on it a piece of _bona fide_ scotch pumice. this gentleman, well known through his exertions in statistical science, and for his love of science in general, and whose tastes and acquirements are not unworthy the son of mrs. somerville, has kindly informed me by letter regarding his curious discovery. "i visited the island of eigg," he says, "in or , for the purpose of shooting, and remained in it several days; and as there was a great scarcity of game, i amused myself in my wanderings by looking about for natural curiosities. i knew little about geology at the time, but, collecting whatever struck my eye as uncommon, i picked up from the sides of the scuir, among various other things, a bit of fossil wood, and, nearly at the summit of the eminence, a piece of pumice of a deep brownish-black color, and very porous, the pores being large and round, and the substance which divided them of a uniform thickness. this last specimen i gave to mr. lyell, who said that it could not originally have belonged to eigg, though it might possibly have been washed there by the sea,--a suggestion, however, with which its place on the top of the scuir seems ill to accord. i may add, that i have since procured a larger specimen from the same place." this seems a curious fact, when we take into account the identity, in their mineral components, of the pumice and obsidian of the recent volcanoes; and that pitchstone, the obsidian of the trap-rocks, is resolvable into a pumice by the art of the chemist. if pumice was to be found anywhere in scotland, we might _a priori_ expect to find it in connection with by far the largest mass of pitchstone in the kingdom. it is just possible, however, that mr. greig's two specimens may not date farther back, in at least their existing state, than the days of the hill-fort. powerful fires would have been required to render the exposed summit of the scuir at all comfortable; there is a deep peat-moss in its immediate neighborhood, that would have furnished the necessary fuel; the wind must have been sufficiently high on the summit to fan the embers into an intense white heat; and if it was heat but half as intense as that which was employed in fusing into one mass the thick vitrified ramparts of craig phadrig and knock farril, on the east coast, it could scarce have failed to anticipate the experiment of the hon. mr. knox, of dublin, by converting some of the numerous pitchstone fragments that lie scattered about, "into a light substance in every respect resembling pumice." it was now evening, and rarely have i witnessed a finer. the sun had declined half-way adown the western sky, and for many yards the shadow of the gigantic scuir lay dark beneath us along the descending slope. all the rest of the island, spread out at our feet as in a map, was basking in yellow sunshine; and with its one dark shadow thrown from its one mountain-elevated wall of rock, it seemed some immense fantastical dial, with its gnomon rising tall in the midst. far below, perched on the apex of the shadow, and half lost in the line of the penumbra, we could see two indistinct specks of black, with a dim halo around each,--specks that elongated as we arose, and contracted as we sat, and went gliding along the line as we walked. the shadows of two gnats disporting on the edge of an ordinary gnomon would have seemed vastly more important, in proportion, on the figured plane of the dial, than these, our ghostly representatives, did here. the sea, spangled in the wake of the sun with quick glancing light, stretched out its blue plain around us; and we could see included in the wide prospect, on the one hand, at once the hill-chains of morven and kintail, with the many intervening lochs and bold jutting headlands that give variety to the mainland; and, on the other, the variously complexioned hebrides, from the isle of skye to uist and barra, and from uist and barra to tiree and mull. the contiguous small isles, muck and rum, lay moored immediately beside us, like vessels of the same convoy that in some secure roadstead drop anchor within hail of each other. i could willingly have lingered on the top of the scuir until after sunset; but the minister, who, ever and anon, during the day, had been conning over some notes jotted on a paper of wonderfully scant dimensions, reminded me that this was the evening of his week-day discourse, and that we were more than a particularly rough mile from the place of meeting, and within, half an hour of the time. i took one last look of the scene ere we commenced our descent. there, in the middle of the ample parish glebe, that looked richer and greener in the light of the declining sun than at any former period during the day,--rose the snug parish manse; and yonder,--in an open island channel, with a strip of dark rocks fringing the land within, and another dark strip fringing the barren eilean chaisteil outside,--lay the betsey, looking wonderfully diminutive, but evidently a little thing of high spirit, taut-masted, with a smart rake aft, and a spruce outrigger astern, and flaunting her triangular flag of blue in the sun. i pointed first to the manse, and then to the yacht. the minister shook his head. "'tis a time of strange changes," he said; "i thought to have lived and died in that house, and found a quiet grave in the burying-ground yonder beside the ruin; but my path was a clear though a rugged one; and from almost the moment that it opened up to me, i saw what i had to expect. it has been said that i might have lain by here in this out-of-the-way corner, and suffered the church question to run its course, without quitting my hold of the establishment. and so i perhaps might. it is easy securing one's own safety, in even the worst of times, if one look no higher; and i, as i had no opportunity of mixing in the contest, or of declaring my views respecting it, might be regarded as an unpledged man. but the principles of the evangelical party were my principles; and it would have been consistent with neither honor nor religion to have hung back in the day of battle, and suffered the men with whom in heart i was at one to pay the whole forfeit of our common quarrel. so i attended the convocation, and pledged myself to stand or fall with my brethren. on my return i called my people together, and told them how the case stood, and that in may next i bade fair to be a dependent for a home on the proprietor of eigg. and so they petitioned the proprietor that he might give me leave to build a house among them,--exactly the same sort of favor granted to the roman catholics of the island. but month after month passed, and they got no reply to their petition; and i was left in suspense, not knowing whether i was to have a home among them or no. i did feel the case a somewhat hard one. the father of dr. m'pherson of eigg had been, like myself, a humble scotch minister; and the doctor, however indifferent to his people's wishes in such a matter, might have just thought that a man in his father's station in life, with a wife and family dependent on him, was placed by his silence in cruel circumstances of uncertainty. ere the disruption took place, however, i came to know pretty conclusively what i had to expect. the doctor's factor came to eigg, and, as i was informed, told the islanders that it was not likely the doctor would permit a _third_ place of worship on the island: the roman catholics had one, and the establishment had a kind of one, and there was to be no more. the factor, an active messenger-at-arms, useful in raising rents in these parts, has always been understood to speak the mind of his master; but the congregation took heart in the emergency, and sent off a second petition to dr. m'pherson, a week or so previous to the disruption. ere _it_ received an answer, the disruption took place; and, laying the whole circumstances before my brethren in edinburgh, who, like myself, interpreted the silence of the doctor into a refusal, i suggested to them the scheme of the betsey, as the only scheme through which i could keep up unbroken my connection with my people. so the trial is now over, and here we are, and yonder is the betsey." we descended the scuir together for the place of meeting, and entered, by the way, the cottage of a worthy islander, much attached to his minister. "we are both very hungry," said my friend: "we have been out among the rocks since breakfast-time, and are wonderfully disposed to eat. do not put yourself about, but give us anything you have at hand." there was a bowl of rich milk brought us, and a splendid platter of mashed potatoes, and we dined like princes. i observed, for the first time, in the interior of this cottage, what i had frequent occasion to remark afterwards, that much of the wood used in building in the smaller and outer islands of the hebrides must have drifted across the atlantic, borne eastwards and northwards by the great gulf-stream. many of the beams and boards, sorely drilled by the _teredo navalis_, are of american timber, that, from time to time, has been cast upon the shore,--a portion of it, apparently, from timber-laden vessels unfortunate in their voyage, but a portion of it, also, with root and branch still attached, bearing mark of having been swept to the sea by transatlantic rivers. nuts and seeds of tropical plants are occasionally picked up on the beach. my friend gave me a bean or nut of the _dolichos urens_, or cow-itch shrub, of the west indies, which an islander had found on the shore sometime in the previous year, and given to one of the manse children as a toy; and i attach some little interest to it, as a curiosity of the same class with the large canes and the fragment of carved wood found floating near the shores of madeira by the brother-in-law of columbus, and which, among other pieces of circumstantial evidence, led the great navigator to infer the existence of a western continent. curiosities of this kind seem still more common in the northern than in the western islands of scotland. "large exotic nuts or seeds," says dr. patrick neill, in his interesting "tour," quoted in a former chapter, "which in orkney are known by the name of molucca beans, are occasionally found among the _rejectamenta_ of the sea, especially after westerly winds. there are two kinds commonly found: the larger (of which the fishermen very generally make snuff-boxes) seem to be seeds from the great pod of the _mimosa scandens_ of the west indies; the smaller seeds, from the pod of the _dolichos urens_, also a native of the same region. it is probable that the currents of the ocean, and particularly that great current which issues from the gulf of florida, and is hence denominated the gulf stream, aid very much in transporting across the mighty atlantic these american products. they are generally quite fresh and entire, and afford an additional proof how impervious to moisture, and how imperishable, nuts and seeds generally are." the evening was fast falling ere the minister closed his discourse; and we had but just light enough left, on reaching the betsey, to show us that there lay a dead sheep on the deck. it had been sent aboard to be killed by the minister's factotum, john stewart; but john was at the evening preaching at the time, and the poor sheep, in its attempts to set itself free, had got itself entangled among the cords, and strangled itself. "alas, alas!" exclaimed the minister, "thus ends our hope of fresh mutton for the present, and my hapless speculation as a sheep farmer for evermore." i learned from him, afterwards, over our tea, that shortly previous to the convocation he had got his glebe,--one of the largest in scotland,--well stocked with sheep and cattle, which he had to sell, immediately on the disruption, in miserably bad condition, at a loss of nearly fifty per cent. he had a few sheep, however, that would not sell at all, and that remained on the glebe, in consequence, until his successor entered into possession. and he, honest man, straightway impounded them, and got them incarcerated in a dark, dirty hole, somewhat in the way giant despair incarcerated the pilgrims,--a thing he had quite a legal right to do, seeing that the mile-long glebe, with its many acres of luxuriant pasture, was now as much his property as it had been mr. swanson's a few months before, and seeing mr. swanson's few sheep had no right to crop his grass. but a worthy neighbor interfered,--mr. m'donald, of keil, the principal tenant in the island. mr. m'donald,--a practical commentator on the law of kindness,--was sorely scandalized at what he deemed the new minister's gratuitous unkindness to a brother in calamity; and, relieving the sheep, he brought them to his own farm, where he found them board and lodging on my friend's behalf, till they could be used up at leisure. and it was one of the last of this unfortunate lot that now contrived to escape from us by anticipating john stewart. "a black beginning makes a black ending," said gouffing jock, an ancient border shepherd, when his only sheep, a black ewe, the sole survivor of a flock smothered in a snow-storm, was worried to death by his dogs. then, taking down his broadsword, he added, "come awa, my auld friend; thou and i maun e'en stock bowerhope-law ance mair!" less warlike than gouffing jock, we were content to repeat over the dead, on this occasion, simply the first portion of his speech; and then, betaking ourselves to our cabin, we forgot all our sorrows over our tea. chapter iv. an excursion--the chain of crosses--bay of laig--island of rum--description of the island--superstitions banished by pure religion--fossil shells--remarkable oyster bed--new species of belemnite--oölitic shells--white sandstone precipices--gigantic petrified mushrooms--"christabel" in stone--musical sand--_jabel nakous_, or mountain of the bell--experiments of travellers at _jabel nakous_--welsted's account--_reg-rawan_, or the moving sand--the musical sounds inexplicable--article on the subject in the north british review. there had been rain during the night; and when i first got on deck, a little after seven, a low stratum of mist, that completely enveloped the scuir, and truncated both the eminence on which it stands and the opposite height, stretched like a ruler across the flat valley which indents so deeply the middle of the island. but the fogs melted away as the morning rose, and ere our breakfast was satisfactorily discussed, the last thin wreath had disappeared from around the columned front of the rock-tower of eigg, and a powerful sun looked down on moist slopes and dank hollows, from which there arose in the calm a hazy vapor, that, while it softened the lower features of the landscape, left the bold outline relieved against a clear sky. accompanied by our attendant of the previous day, bearing bag and hammer, we set out a little before eleven for the north-western side of the island, by a road which winds along the central hollow. my friend showed me as we went, that on the edge of an eminence, on which the traveller journeying westwards catches the last glimpse of the chapel of st. donan, there had once been a rude cross erected, and another rude cross on an eminence on which he catches the last glimpse of the first; and that there had thus been a chain of stations formed from sea to sea, like the sights of a land-surveyor, from one of which a second could be seen, and a third from the second, till, last of all, the emphatically holy point of the island,--the burial-place of the old culdee,--came full in view. the unsteady devotion, that journeyed, fancy-bound, along the heights, to gloat over a dead man's bones, had its clue to carry it on in a straight line. its trail was on the ground; it glided snake-like from cross to cross, in quest of dust; and, without its finger-posts to guide it, would have wandered devious. it is surely a better devotion that, instead of thus creeping over the earth to a mouldy sepulchre, can at once launch into the sky, secure of finding him who once arose from one. in less than an hour we were descending on the bay of laig, a semi-circular indentation of the coast, about a mile in length, and, where it opens to the main sea, nearly two miles in breadth; with the noble island of rum rising high in front, like some vast breakwater; and a meniscus of comparatively level land, walled in behind by a semi-circular rampart of continuous precipice, sweeping round its shores. there are few finer scenes in the hebrides than that furnished by this island bay and its picturesque accompaniments,--none that break more unexpectedly on the traveller who descends upon it from the east; and rarely has it been seen, to greater advantage than on the delicate day, so soft, and yet so sunshiny and clear, on which i paid it my first visit. the island of rum, with its abrupt sea-wall of rock, and its steep-pointed hills, that attain, immediately over the sea, an elevation of more than two thousand feet, loomed bold and high in the offing, some five miles away, but apparently much nearer. the four tall summits of the island rose clear against the sky like a group of pyramids; its lower slopes and precipices, variegated and relieved by graceful alternations of light and shadow, and resting on their blue basement of sea, stood out with equal distinctness; but the entire middle space from end to end was hidden in a long horizontal stratum of gray cloud, edged atop with a lacing of silver. such was the aspect of the noble breakwater in front. fully two-thirds of the semi-circular rampart of rock which shuts in the crescent-shaped plain directly opposite lay in deep shadow; but the sun shone softly on the plain itself, brightening up many a dingy cottage, and many a green patch of corn; and the bay below stretched out, sparkling in the light. there is no part of the island so thickly inhabited as this flat meniscus. it is composed almost entirely of oölitic rocks, and bears atop, especially where an ancient oyster-bed of great depth forms the subsoil, a kindly and fertile mould. the cottages lie in groups; and, save where a few bogs, which it would be no very difficult matter to drain, interpose their rough shag of dark green, and break the continuity, the plain around them waves with corn. lying fair, green and populous within the sweep of its inaccessible rampart of rock, at least twice as lofty as the ramparts of babylon of old, it reminds one of the suburbs of some ancient city lying embosomed, with all its dwellings and fields, within some roomy crescent of the city wall. we passed, ere we entered on the level, a steep-sided narrow dell, through which a small stream finds its way from the higher grounds, and which terminates at the upper end in an abrupt precipice, and a lofty but very slim cascade. "one of the few superstitions that still linger on the island," said my friend the minister, "is associated with that wild hollow. it is believed that shortly before a death takes place among the inhabitants, a tall withered female may be seen in the twilight, just yonder where the rocks open, washing a shroud in the stream. john, there, will perhaps tell you how she was spoken to on one occasion, by an over-bold, over-inquisitive islander, curious to know whose shroud she was preparing; and how she more than satisfied his curiosity, by telling him it was his own. it is a not uninteresting fact," added the minister, "that my poor people, since they have become more earnest about their religion, think very little about ghosts and spectres: their faith in the realities of the unseen world seems to have banished from their minds much of their old belief in its phantoms." in the rude fences that separate from each other the little farms in this plain, we find frequent fragments of the oyster bed, hardened into a tolerably compact limestone. it is seen to most advantage, however, in some of the deeper cuttings in the fields, where the surrounding matrix exists merely as an incoherent shale; and the shells may be picked out as entire as when they lay, ages before, in the mud, which we still see retaining around them its original color. they are small, thin, triangular, much resembling in form some specimens of the _ostrea deltoidea_, but greatly less in size. the nearest resembling shell in sowerby is the _ostrea acuminata_,--an oyster of the clay that underlies the great oölite of bath. few of the shells exceed an inch and a half in length, and the majority fall short of an inch. what they lack in bulk, however, they make up in number. they are massed as thickly together, to the depth of several feet, as shells on the heap at the door of a newhaven fisherman, and extend over many acres. where they lie open we can still detect the triangular disc of the hinge, with the single impression of the abductor muscle; and the foliaceous character of the shell remains in most instances as distinct as if it had undergone no mineral change. i have seen nowhere in scotland, among the secondary formations, so unequivocal an oyster-bed; nor do such beds seem to be at all common in formations older than the tertiary in england, though the oyster itself is sufficiently so. we find mantell stating, in his recent work ("medals of creation"), after first describing an immense oyster bed of the london basin, that underlies the city (for what is now london was once an oyster-bed), that in the chalk below, though it contains several species of ostrea, the shells are diffused promiscuously throughout the general mass. leaving, however, these oysters of the oölite, which never net inclosed nor drag disturbed, though they must have formed the food of many an extinct order of fish,--mayhap reptile,--we pass on in a south-western direction, descending in the geological scale as we go, until we reach the southern side of the bay of laig. and there, far below tide-mark, we find a dark-colored argillaceous shale of the lias, greatly obscured by boulders of trap,--the only deposit of the liasic formation in the island. a line of trap-hills that rises along the shore seems as if it had strewed half its materials over the beach. the rugged blocks lie thick as stones in a causeway, down to the line of low ebb,--memorials of a time when the surf dashed against the shattered bases of the trap-hills, now elevated considerably beyond its reach; and we can catch but partial glimpses of the shale below. wherever access to it can be had, we find it richly fossiliferous; but its organisms, with the exception of its belemnites, are very imperfectly preserved. i dug up from under the trap-blocks some of the common liasic ammonites of the north-eastern coast of scotland, a few of the septa of a large nautilus, broken pieces of wood, and half-effaced casts of what seems a branched coral; but only minute portions of the shells have been converted into stone; here and there a few chambers in the whorls of an ammonite or nautilus, though the outline of the entire organism lies impressed in the shale; and the ligneous and polyparious fossils we find in a still greater state of decay. the belemnite alone, as is common with this robust fossil,--so often the sole survivor of its many contemporaries,--has preserved its structure entire. i disinterred from the shale good specimens of the belemnite _sulcatus_ and belemnite _elongatus_, and found, detached on the surface of the bed, a fragment of a singularly large belemnite, a full inch and a quarter in diameter, the species of which i could not determine. returning by the track we came, we reach the bottom of the bay, which we find much obscured with sand and shingle; and pass northwards along its side, under a range of low sandstone precipices, with interposing grassy slopes, in which the fertile oölitic meniscus descends to the beach. the sandstone, white and soft, and occurring in thick beds, much resembles that of the oölite of sutherland. we detect in it few traces of fossils; now and then a carbonaceous marking, and now and then what seems a thin vein of coal, but which proves to be merely the bark of some woody stem, converted into a glossy bituminous lignite, like that of brora. but in beds of a blue clay, intercalated with the sandstone, we find fossils in abundance, of a character less obscure. we spent a full half-hour in picking out shells from the bottom of a long dock-like hollow among the rocks, in which a bed of clay has yielded to the waves, while the strata on either side stand up over it like low wharfs on the opposite side of a river. the shells, though exceedingly fragile,--for they partake of the nature of the clayey matrix in which they are imbedded,--rise as entire as when they had died among the mud, years, mayhap ages, ere the sandstone had been deposited over them; and we were enabled at once to detect their extreme dissimilarity, as a group, to the shells of the liasic deposit we had so lately quitted. we did not find in this bed a single ammonite, belemnite, or nautilus; but chalky bivalves, resembling our existing tellina, in vast abundance, mixed with what seem to be a small buccinum and a minute trochus, with numerous rather equivocal fragments of a shell resembling an oiliva. so thickly do they lie clustered together in this deposit, that in some patches where the sad-colored argillaceous ground is washed bare by the sea, it seems marbled with them into a light gray tint. the group more nearly resembles in type a recent one than any i have yet seen in a secondary deposit, except perhaps in the weald of moray, where we find in one of the layers a planorbis scarce distinguishable from those of our ponds and ditches, mingled with a paludina that seems as nearly modelled after the existing form. from the absence of the more characteristic shells of the oölite, i am inclined to deem the deposit one of estuary origin. its clays were probably thrown down, like the silts of so many of our rivers, in some shallow bay, where the waters of a descending stream mingled with those of the sea, and where, though shells nearly akin to our existing periwinkles and whelks congregate thickly, the belemnite, seared by the brackish water, never plied its semi-cartilaginous fins, or the nautilus or ammonite hoisted its membranaceous sail. we pass on towards the north. a thick bed of an extremely soft white sandstone presents here, for nearly half a mile together, its front to the waves, and exhibits, under the incessant wear of the surf, many singularly grotesque combinations of form. the low precipices, undermined at the base, beetle over like the sides of stranded vessels. one of the projecting promontories we find hollowed through and through by a tall rugged archway; while the outer pier of the arch,--if pier we may term it,--worn to a skeleton, and jutting outwards with a knee-like angle, presents the appearance of a thin ungainly leg and splay foot, advanced, as if in awkward courtesy, to the breakers. but in a winter or two, judging from its present degree of attenuation, and the yielding nature of its material, which resembles a damaged mass of arrow-root, consolidated by lying in the leaky hold of a vessel, its persevering courtesies will be over, and pier and archway must lie in shapeless fragments on the beach. wherever the surf has broken into the upper surface of this sandstone bed, and worn it down to nearly the level of the shore, what seem a number of double ramparts, fronting each other, and separated by deep square ditches exactly parallel in the sides, traverse the irregular level in every direction. the ditches vary in width from one to twelve feet; and the ramparts, rising from three to six feet over them, are perpendicular as the walls of houses, where they front each other, and descend on the opposite sides in irregular slopes. the iron block, with square groove and projecting ears, that receives the bar of a railway, and connects it with the stone below, represents not inadequately a section of one of these ditches, with its ramparts. they form here the sole remains of dykes of an earthy trap, which, though at one time in a state of such high fusion that they converted the portions of soft sandstone in immediate contact with them into the consistence of quartz rock, have long since mouldered away, leaving but the hollow rectilinear rents which they had occupied, surmounted by the indurated walls which they had baked. some of the most curious appearances, however, connected with the sandstone, though they occur chiefly in an upper bed, are exhibited by what seem fields of petrified mushrooms, of a gigantic size, that spread out in some places for hundreds of yards under the high-water level. these apparent mushrooms stand on thick squat stems, from a foot to eighteen inches in height; the heads are round like those of toad-stools, and vary from one foot to nearly two yards in diameter. in some specimens we find two heads joined together in a form resembling a squat figure of _eight_, of what printers term the egyptian type, or, to borrow the illustration of m'culloch, "like the ancient military projectile known by the name of double-headed shot;" in other specimens three heads have coalesced in a trefoil shape, or rather in a shape like that of an ace of clubs divested of the stem. by much the greater number, however, are spherical. they are composed of concretionary masses, consolidated, like the walls of the dykes, though under some different process, into a hard siliceous stone, that has resisted those disintegrating influences of the weather and the surf, under which the yielding matrix in which they were embedded has worn from around them. here and there we find them lying detached on the beach, like huge shot, compared with which the greenstone balls of mons meg are but marbles for children to play with; in other cases they project from the mural front of rampart-like precipices, as if they had been showered into them by the ordnance of some besieging battery, and had stuck fast in the mason-work. abbotsford has been described as a romance in stone and lime; we have here, on the shores of laig, what seems a wild but agreeable tale, of the extravagant cast of "christabel," or the "rhyme of the ancient mariner," fretted into sandstone. but by far the most curious part of the story remains to be told. the hollows and fissures of the lower sandstone bed we find filled with a fine quartzose sand, which, from its pure white color, and the clearness with which the minute particles reflect the light, reminds one of accumulations of potato-flour drying in the sun. it is formed almost entirely of disintegrated particles of the soft sandstone; and as we at first find it occurring in mere handfuls, that seem as if they had been detached from the mass during the last few tides, we begin to marvel to what quarter the missing materials of the many hundred cubic yards of rock, ground down along the shore in this bed during the last century or two, have been conveyed away. as we pass on northwards, however, we see the white sand occurring in much larger quantities,--here heaped up in little bent-covered hillocks above the reach of the tide,--there stretching out in level, ripple-marked wastes into the waves,--yonder rising in flat narrow spits among the shallows. at length we reach a small, irregularly-formed bay, a few hundred feet across, floored with it from side to side; and see it, on the one hand, descending deep into the sea, that exhibits over its whiteness a lighter tint of green, and, on the other, encroaching on the land, in the form of drifted banks, covered with the plants common to our tracts of sandy downs. the sandstone bed that has been worn down to form it contains no fossils, save here and there a carbonaceous stem; but in an underlying harder stratum we occasionally find a few shells; and, with a specimen in my hand charged with a group of bivalves resembling the existing conchifera of our sandy beaches, i was turning aside this sand of the oölite, so curiously reduced to its original state, and marking how nearly the recent shells that lay embedded in it resembled the extinct ones that had lain in it so long before, when i became aware of a peculiar sound that it yielded to the tread, as my companions paced over it. i struck it obliquely with my foot, where the surface lay dry and incoherent in the sun, and the sound elicited was a shrill, sonorous note, somewhat resembling that produced by a waxed thread, when tightened between the teeth and the hand, and tipped by the nail of the forefinger. i walked over it, striking it obliquely at each step, and with every blow the shrill note was repeated. my companions joined me; and we performed a concert, in which, if we could boast of but little variety in the tones produced, we might at least challenge all europe for an instrument of the kind which produced them. it seemed less wonderful that there should be music in the granite of memnon, than in the loose oölitic sand of the bay of laig. as we marched over the drier tracts, an incessant _woo_, _woo_, _woo_, rose from the surface, that might be heard in the calm some twenty or thirty yards away; and we found that where a damp semi-coherent stratum lay at the depth of three or four inches beneath, and all was dry and incoherent above, the tones were loudest and sharpest, and most easily evoked by the foot. our discovery,--for i trust i may regard it as such,--adds a third locality to two previously known ones, in which what may be termed the musical sand,--no unmeet counterpart to the "singing water" of the tale,--has now been found. and as the island of eigg is considerably more accessible than _jabel nakous_, in arabia petræa, or _reg-rawan_, in the neighborhood of cabul, there must be facilities presented through the discovery which did not exist hitherto, for examining the phenomenon in acoustics which it exhibits,--a phenomenon, it may be added, which some of our greatest masters of the science have confessed their inability to explain. _jabel nakous_, or the "mountain of the bell," is situated about three miles from the shores of the gulf of suez, in that land of wonders which witnessed for forty years the journeyings of the israelites, and in which the granite peaks of sinai and horeb overlook an arid wilderness of rock and sand. it had been known for many ages by the wild arab of the desert, that there rose at times from this hill a strange, inexplicable music. as he leads his camel past in the heat of the day, a sound like the first low tones of an Æolian harp stirs the hot breezeless air. it swells louder and louder in progressive undulations, till at length the dry baked earth seems to vibrate under foot, and the startled animal snorts and rears, and struggles to break away. according to the arabian account of the phenomenon, says sir david brewster, in his "letters on natural magic," there is a convent miraculously preserved in the bowels of the hill; and the sounds are said to be those of the "_nakous_, a long metallic ruler, suspended horizontally, which the priest strikes with a hammer, for the purpose of assembling the monks to prayer." there exists a tradition that on one occasion a wandering greek saw the mountain open, and that, entering by the gap, he descended into the subterranean convent, where he found beautiful gardens and fountains of delicious water, and brought with him to the upper world, on his return, fragments of consecrated bread. the first european traveller who visited _jabel nakous_, says sir david, was m. seetzen, a german. he journeyed for several hours over arid sands, and under ranges of precipices inscribed by mysterious characters, that tell, haply, of the wanderings of israel under moses. and reaching, about noon, the base of the musical fountain, he found it composed of a white friable sandstone, and presenting on two of its sides sandy declivities. he watched beside it for an hour and a quarter, and then heard, for the first time, a low undulating sound, somewhat resembling that of a humming top, which rose and fell, and ceased and began, and then ceased again; and in an hour and three quarters after, when in the act of climbing along the declivity, he heard the sound yet louder and more prolonged. it seemed as if issuing from under his knees, beneath which the sand, disturbed by his efforts, was sliding downwards along the surface of the rock. concluding that the sliding sand was the cause of the sounds, not an effect of the vibrations which they occasioned, he climbed to the top of one of the declivities, and, sliding downwards, exerted himself with hands and feet to set the sand in motion. the effect produced far exceeded his expectations; the incoherent sand rolled under and around in a vast sheet; and so loud was the noise produced, that "the earth seemed to tremble beneath him to such a degree, that he states he should certainly have been afraid if he had been ignorant of the cause." at the time sir david brewster wrote ( ), the only other european who had visited _jabel nakous_ was mr. gray, of university college, oxford. this gentleman describes the noises he heard, but which he was unable to trace to their producing cause, as "beginning with a low continuous murmuring sound, which seemed to rise beneath his feet," but "which gradually changed into pulsations as it became louder, so as to resemble the striking of a clock, and became so strong at the end of five minutes _as to detach the sand_." the mountain of the bell has been since carefully explored by lieutenant j. welsted, of the indian navy; and the reader may see it exhibited in a fine lithograph, in his travels, as a vast irregularly conical mass of broken stone, somewhat resembling one of our highland cairns, though, of course, on a scale immensely more huge, with a steep, angular slope of sand resting in a hollow in one of its sides, and rising to nearly its apex. "it forms," says lieutenant welsted, "one of a ridge of low, calcareous hills, at a distance of three and a half miles from the beach, to which a sandy plain, extending with a gentle rise to their base, connects them. its height, about four hundred feet, as well as the material of which it is composed,--a light-colored friable sandstone,--is about the same as the rest of the chain; but an inclined plane of almost impalpable sand rises at an angle of forty degrees with the horizon, and is bounded by a semi-circle of rocks, presenting broken, abrupt, and pinnacled forms, and extending to the base of this remarkable hill. although their shape and arrangement in some respects may be said to resemble a whispering gallery, yet i determined by experiment that their irregular surface renders them but ill adapted for the production of an echo. seated at a rock at the base of the sloping eminence, i directed one of the bedouins to ascend; and it was not until he had reached some distance that i perceived the sand in motion, rolling down the hill to the depth of a foot. it did not, however, descend in one continued stream; but, as the arab scrambled up, it spread out laterally and upwards, until a considerable portion of the surface was in motion. at their commencement the sounds might be compared to the faint strains of an Æolian harp when its strings first catch the breeze: as the sand became more violently agitated by the increased velocity of the descent, the noise more nearly resembled that produced by drawing the moistened fingers over glass. as it reached the base, the reverberations attained the loudness of distant thunder, causing the rock on which we were seated to vibrate; and our camels,--animals not easily frightened,--became so alarmed that it was with difficulty their drivers could restrain them." "the hill of _reg-rawan_ or the 'moving sand,'" says the late sir alexander burnes, by whom the place was visited in the autumn of , and who has recorded his visit in a brief paper, illustrated by a rude lithographic view, in the "journal of the asiatic society" for , "is about forty miles north of cabul, towards hindu-kush, and near the base of the mountains." it rises to the height of about four hundred feet, in an angle formed by the junction of two ridges of hills; and a sheet of sand, "pure as that of the sea-shore," and which slopes in an angle of forty degrees, reclines against it from base to summit. as represented in the lithograph, there projects over the steep sandy slope on each side, as in the "mountain of the bell," still steeper barriers of rock; and we are told by sir alexander, that though "the mountains here are generally composed of granite or mica, at _reg-rawan_ there is sandstone and lime." the situation of the sand is curious, he adds: it is seen from a great distance; and as there is none other in the neighborhood, "it might almost be imagined, from its appearance, that the hill had been cut in two, and that the sand had gushed forth as from a sand-bag." "when set in motion by a body of people who slide down it, a sound is emitted. on the first trial we distinctly heard two loud hollow sounds, such as would be given by a large drum;"--"there is an echo in the place; and the inhabitants have a belief that the sounds are only heard on friday, when the saint of _reg-rawan_, who is interred hard by, permits." the phenomenon, like the resembling one in arabia, seems to have attracted attention among the inhabitants of the country at an early period; and the notice of an eastern annalist, the emperor baber, who flourished late in the fifteenth century, and, like cæsar, conquered and recorded his conquests, still survives. he describes it as the _khwaja reg-rawan_, "a small hill, in which there is a line of sandy ground reaching from the top to the bottom," from which there "issues in the summer season the sound of drums and nagarets." in connection with the fact that the musical sand of eigg is composed of a disintegrated sandstone of the oölite, it is not quite unworthy of notice that sandstone and lime enter into the composition of the hill of _reg-rawan_,--that the district in which the hill is situated is not a sandy one,--and that its slope of sonorous sand seems as if it had issued from its side. these various circumstances, taken together, lead to the inference that the sand may have originated in the decomposition of the rock beneath. it is further noticeable, that the _jabel nakous_ is composed of a white friable sandstone, resembling that of the white friable bed of the bay of laig, and that it belongs to nearly the same geological era. i owe to the kindness of dr. wilson of bombay, two specimens which he picked up in arabia petræa, of spines of cidarites of the mace-formed type so common in the chalk and oölite, but so rare in the older formations. dr. wilson informs me that they are of frequent occurrence in the desert of arabia petræa, where they are termed by the arabs petrified olives; that nummulites are also abundant in the district; and that the various secondary rocks he examined in his route through it seem to belong to the cretaceous group. it appears not improbable, therefore, that all the sonorous sand in the world yet discovered is formed, like that of eigg, of disintegrated sandstone; and at least two-thirds of it of the disintegrated sandstone of secondary formations, newer than the lias. but how it should be at all sonorous, whatever its age or origin, seems yet to be discovered. there are few substances that appear worse suited than sand to communicate to the atmosphere those vibratory undulations that are the producing causes of sound: the grains, even when sonorous individually, seem, from their inevitable contact with each other, to exist under the influence of that simple law in acoustics which arrests the tones of the ringing glass or struck bell, immediately as they are but touched by some foreign body, such as the hand or finger. the one grain, ever in contact with several other grains, is a glass or bell on which the hand always rests. and the difficulty has been felt and acknowledged. sir john herschel, in referring to the phenomenon of the _jabel nakous_, in his "treatise on sound," in the "encyclopædia metropolitana," describes it as to him "utterly inexplicable;" and sir david brewster, whom i had the pleasure of meeting in december last, assured me it was not less a puzzle to him than to sir john. an eastern traveller, who attributes its production to "a reduplication of impulse setting air in vibration in a focus of echo," means, i suppose, saying nearly the same thing as the two philosophers, and merely conveys his meaning in a less simple style. i have not yet procured what i expect to procure soon,--sand enough from the musical bay at laig to enable me to make its sonorous qualities the subject of experiment at home. it seems doubtful whether a small quantity set in motion on an artificial slope will serve to evolve the phenomena which have rendered the mountain of the bell so famous. lieutenant welsted informs us, that when his bedouin first set the sand in motion, there was scarce any perceptible sound heard;--it was rolling downwards for many yards around him to the depth of a foot, ere the music arose; and it is questionable whether the effect could be elicited with some fifty or sixty pounds weight of the sand of eigg, on a slope of but at most a few feet, which it took many hundred weight of sand of _jabel nakous_, and a slope of many yards, to produce. but in the stillness of a close room, it is just possible that it may. i have, however, little doubt, that from small quantities the sound evoked by the foot on the shore may be reproduced: enough will lie within the reach of experiment to demonstrate the strange difference which exists between this sonorous sand of the oölite, and the common unsonorous sand of our sea-beaches; and it is certainly worth while examining into the nature and producing causes of a phenomenon so curious in itself, and which has been characterized by one of the most distinguished of living philosophers as "the most celebrated of all the acoustic wonders which the natural world presents to us." in the forthcoming number of the "north british review,"--which appears on monday first,[ ]--the reader will find the sonorous sand of eigg referred to, in an article the authorship of which will scarcely be mistaken. "we have here," says the writer, after first describing the sounds of _jabel nakous_, and then referring to those of eigg, "the phenomenon in its simple state, disembarrassed from reflecting rocks, from a hard bed beneath, and from cracks and cavities that might be supposed to admit the sand; and indicating as its cause, either the accumulated vibration of the air when struck by the driven sand, or the accumulated sounds occasioned by the mutual impact of the particles of sand against each other. if a musket-ball passing through the air emits a whistling note, each individual particle of sand must do the same, however faint be the note which it yields; and the accumulation of these infinitesimal vibrations must constitute an audible sound, varying with the number and velocity of moving particles. in like manner, if two plates of silex or quartz, which are but large crystals of sand, give out a musical sound when mutually struck, the impact or collision of two minute crystals or particles of sand must do the same, in however inferior a degree; and the union of all these sounds, though singly imperceptible, may constitute the musical notes of the bell mountain, or the lesser sounds of the trodden sea-beach at eigg." here is a vigorous effort made to unlock the difficulty. i should, however, have mentioned to the philosophic writer,--what i inadvertently failed to do,--that the sounds elicited from the sand of eigg seem as directly evoked by the slant blow dealt it by the foot, as the sounds similarly evoked from a highly waxed floor, or a board strewed over with ground rosin. the sharp shrill note follows the stroke, altogether independently of the grains driven into the air. my omission may serve to show how much safer it is for those minds of the observant order, that serve as hands and eyes to the reflective ones, to prefer incurring the risk of being even tediously minute in their descriptions, to the danger of being inadequately brief in them. but, alas! for purposes of exact science, rarely are verbal descriptions otherwise than inadequate. let us look, for example, at the various accounts given us of _jabel nakous_. there are strange sounds heard proceeding from a hill in arabia, and various travellers set themselves to describe them. the tones are those of the convent _nakous_, says the wild arab;--there must be a convent buried under the hill. more like the sounds of a humming-top, remarks a phlegmatic german traveller. not quite like them, says an english one in an oxford gown;--they resemble rather the striking of a clock. nay, listen just a little longer and more carefully, says a second englishman, with epaulettes on his shoulder: "the sounds at their commencement may be compared to the faint strains of an Æolian harp when its strings first catch the breeze," but anon, as the agitation of the sand increases, they "more nearly resemble those produced by drawing the moistened fingers over glass." not at all, exclaims the warlike zahor ed-din muhammed baber, twirling his whiskers: "i know a similar hill in the country towards hindu-kush: it is the sound of drums and nagarets that issues from the sand." all we really know of this often-described music of the desert, after reading all the descriptions, is, that its tones bear certain analogies to certain other tones,--analogies that seem stronger in one direction to one ear, and stronger in another direction to an ear differently constituted, but which do not exactly resemble any other sounds in nature. the strange music of _jabel nakous_, as a combination of tones, is essentially unique. chapter v. trap-dykes--"cotton apples"--alternation of lacustrine with marine remains--analogy from the beds of esk--aspect of the island on its narrow front--the puffin--ru-stoir--development of old red sandstone--striking columnar character of ru-stoir--discovery of reptilian remains--john stewart's wonder at the bones in the stones--description of the bones--"dragons, gorgons, and chimeras"--exploration and discovery pursued--the midway shieling--a celtic welcome--return of the yacht--"array of fossils new to scotch geology"--a geologist's toast--hoffman and his fossil. we leave behind us the musical sand, and reach the point of the promontory which forms the northern extremity of the bay of laig. wherever the beach has been swept bare, we see it floored with trap-dykes worn down to the level, but in most places accumulations of huge blocks of various composition cover it up, concealing the nature of the rock beneath. the long semi-circular wall of precipice which, sweeping inwards at the bottom of the bay, leaves to the inhabitants between its base and the beach their fertile meniscus of land, here abuts upon the coast. we see its dark forehead many hundred feet overhead, and the grassy platform beneath, now narrowed to a mere talus, sweeping upwards to its base from the shore,--steep, broken, lined thick with horizontal pathways, mottled over with ponderous masses of rock. among the blocks that load the beach, and render our onward progress difficult and laborious, we detect occasional fragments of an amygdaloidal basalt, charged with a white zeolite, consisting of crystals so extremely slender that the balls, with their light fibrous contents, remind us of cotton apples divested of the seeds. there occur, though more rarely, masses of a hard white sandstone, abounding in vegetable impressions, which, from their sculptured markings, recalled to memory the sigillaria of the coal measures. here and there, too, we find fragments of a calcareous stone, so largely charged with compressed shells, chiefly bivalves, that it may be regarded as a shell breccia. there occur, besides, slabs of fibrous limestone, exactly resembling the limestone of the ichthyolite beds of the lower old red; and blocks of a hard gray stone, of silky lustre in the fresh fracture, thickly speckled with carbonaceous markings. these fragmentary masses,--all of them, at least, except the fibrous limestone, which occurs in mere plank-like bands,--represent distinct beds, of which this part of the island is composed, and which present their edges, like courses of ashlar in a building, in the splendid section that stretches from the tall brow of the precipice to the beach; though in the slopes of the talus, where the lower beds appear in but occasional protrusions and land-slips, we find some difficulty in tracing their order of succession. near the base of the slope, where the soil has been undermined and the rock laid bare by the waves, there occur beds of a bituminous black shale,--resembling the dark shales so common in the coal measures,--that seem to be of fresh water or estuary origin. their fossils, though numerous, are ill preserved; but we detect in them scales and plates of fishes, at least two species of minute bivalves, one of which very much resembles a cyclas; and in some of the fragments, shells of cypris lie embedded in considerable abundance. after all that has been said and written by way of accounting for those alternations of lacustrine with marine remains, which are of such frequent occurrence in the various formations, secondary and tertiary, from the coal measures downwards, it does seem strange enough that the estuary, or fresh-water lake, should so often in the old geologic periods have changed places with the sea. it is comparatively easy to conceive that the inner hebrides should have once existed as a broad ocean sound, bounded on one or either side by oölitic islands, from which streams descended, sweeping with them, to the marine depths, productions, animal and vegetable, of the land. but it is less easy to conceive, that in that sound, the area covered by the ocean one year should have been covered by a fresh-water lake in perhaps the next, and then by the ocean again a few years after. and yet among the oölitic deposits of the hebrides evidence seems to exist that changes of this nature actually took place. i am not inclined to found much on the apparently fresh-water character of the bituminous shales of eigg;--the embedded fossils are all too obscure to be admitted in evidence; but there can exist no doubt that fresh water, or at least estuary formations, do occur among the marine oölites of the hebrides. sir r. murchison, one of the most cautious, as he is certainly one of the most distinguished, of living geologists, found in a northern district of skye, in , a deposit containing cyclas, paludina, neritina,--all shells of unequivocally fresh-water origin,--which must have been formed, he concludes, in either a lake or estuary. what had been sea at one period had been estuary or lake at another. in every case, however, in which these intercalated deposits are restricted to single strata of no great thickness, it is perhaps safer to refer their formation to the agency of temporary land-floods, than to that of violent changes of level, now elevating and now depressing the surface. there occur, for instance, among the marine oölites of brora,--the discovery of mr. robertson, of inverugie,--two strata containing fresh-water fossils in abundance; but the one stratum is little more than an inch in thickness,--the other little more than a foot; and it seems considerably more probable, that such deposits should have owed their existence to extraordinary land-floods, like those which in devastated the province of moray, and covered over whole miles of marine beach with the spoils of land and river, than that a sea-bottom should have been elevated for their production, into a fresh-water lake, and then let down into a sea-bottom again. we find it recorded in the "shepherd's calendar," that after the thaw which followed the great snow-storm of , there were found on a part of the sands of the solway frith known as the beds of esk, where the tide disgorges much of what is thrown into it by the rivers, "one thousand eight hundred and forty sheep, nine black cattle, three horses, two men, one woman, forty-five dogs, and one hundred and eighty hares, beside a number of meaner animals." a similar storm in an earlier time, with a soft sea-bottom prepared to receive and retain its spoils, would have formed a fresh-water stratum intercalated in a marine deposit. rounding the promontory, we lose sight of the bay of laig, and find the narrow front of the island that now presents itself exhibiting the appearance of a huge bastion. the green talus slopes upwards, as its basement, for full three hundred feet; and a noble wall of perpendicular rock, that towers over and beyond for at least four hundred feet more, forms the rampart. save towards the sea, the view is of but limited extent; we see it restricted, on the landward side, to the bold face of the bastion; and in a narrow and broken dell that runs nearly parallel to the shore for a few hundred yards between the top of the talus and the base of the rampart,--a true covered way,--we see but the rampart alone. but the dizzy front of black basalt, dark as night, save where a broad belt of light-colored sandstone traverses it in an angular direction, like a white sash thrown across a funeral robe,--the fantastic peaks and turrets in which the rock terminates atop,--the masses of broken ruins, roughened with moss and lichen, that have fallen from above, and lie scattered at its base,--the extreme loneliness of the place, for we have left behind us every trace of the human family,--and the expanse of solitary sea which it commands,--all conspire to render the scene a profoundly imposing one. it is one of those scenes in which a man feels that he is little, and that nature is great. there is no precipice in the island in which the puffin so delights to build as among the dark pinnacles overhead, or around which the silence is so frequently broken by the harsh scream of the eagle. the sun had got far adown the sky ere we had reached the covered way at the base of the rock. all lay dark below; and the red light atop, half absorbed by the dingy hues of the stone, shone with a gleam so faint and melancholy, that it served but to deepen the effect of the shadows. the puffin, a comparatively rare bird in the inner hebrides, builds, i was told, in great numbers in the continuous line of precipice which, after sweeping for a full mile round the bay of laig, forms the pinnacled rampart here, and then, turning another angle of the island, runs on parallel to the coast for about six miles more. in former times the puffin furnished the islanders, as in st. kilda, with a staple article of food, in those hungry months of summer in which the stores of the old crop had begun to fail, and the new crop had not yet ripened; and the people of eigg, taught by their necessities, were bold cragsmen. but men do not peril life and limb for the mere sake of a meal, save when they cannot help it; and the introduction of the potato has done much to put out the practice of climbing for the bird, except among a few young lads, who find excitement enough in the work to pursue it for its own sake, as an amusement. i found among the islanders what was said to be a piece of the natural history of the puffin, sufficiently apocryphal to remind one of the famous passage in the history of the barnacle, which traced the lineage of the bird to one of the pedunculated cirripedes, and the lineage of the cirripede to a log of wood. the puffin feeds its young, say the islanders, on an oily scum of the sea, which renders it such an unwieldy mass of fat, that about the time when it should be beginning to fly, it becomes unable to get out of its hole. the parent bird, not in the least puzzled, however, treats the case medicinally, and,--like mothers of another two-legged genus, who, when their daughters get over stout, put them through a course of reducing acids to bring them down,--feeds it on sorrel leaves for several days together, till, like a boxer under training, it gets thinned to the proper weight, and becomes able, not only to get out of its cell, but also to employ its wings. we pass through the hollow, and, reaching the farther edge of the bastion, towards the east, see a new range of prospect opening before us. there is first a long unbroken wall of precipice,--a continuation of the tall rampart overhead,--relieved along its irregular upper line by the blue sky. we mark the talus widening at its base, and expanding, as on the shores of the bay of laig, into an irregular grassy platform, that, sinking midway into a ditch-like hollow, rises again towards the sea, and presents to the waves a perpendicular precipice of redstone. the sinking sun shone brightly this evening; and the warm hues of the precipice, which bears the name of _ru-stoir_,--the red head,--strikingly contrasted with the pale and dark tints of the alternating basalts and sandstones in the taller cliff behind. the ditch-like hollow, which seems to indicate the line of a fault, cuts off this red headland from all the other rocks of the island, from which it appears to differ as considerably in texture as in hue. it consists mainly of thick beds of a pale red stone, which m'culloch regarded as a trap, and which, intercalated with here and there a thin band of shale, and presenting not a few of the mineralogical appearances of what geologists of the school of the late mr. cunningham term primary old red sandstone, in some cases has been laid down as a deposit of old red proper, abutting in the line of a fault on the neighboring oölites and basalts. in the geological map which i carried with me,--not one of high authority however,--i found it actually colored as a patch of this ancient system. the old red sandstone is largely developed in the neighboring island of rum, in the line of which the _ru-stoir_ seems to have a more direct bearing than any of the other deposits of eigg; and yet the conclusion regarding this red headland merely adds one proof more to the many furnished already, of the inadequacy of mineralogical testimony, when taken in evidence regarding the eras of the geologist. the hard red beds of _ru-stoir_ belong, as i was fortunate enough this evening to ascertain, not to the ages of the coccosteus and pterichthys, but to the far later ages of the plesiosaurus and the fossil crocodile. i found them associated with more reptilian remains, of a character more unequivocal than have been yet exhibited by any other deposit in scotland. what first strikes the eye, in approaching the _ru-stoir_ from the west, is the columnar character of the stone. the precipices rise immediately over the sea, in rude colonnades of from thirty to fifty feet in height; single pillars, that have fallen from their places in the line, and exhibit a tenacity rare among the trap-rocks,--for they occur in unbroken lengths of from ten to twelve feet,--lie scattered below; and in several places where the waves have joined issue with the precipices in the line on which the base of the columns rest, and swept away the supporting foundation, the colonnades open into roomy caverns, that resound to the dash of the sea. wherever the spray lashes, the pale red hue of the stone prevails, and the angles of the polygonal shafts are rounded; while higher up all is sharp-edged, and the unweathered surface is covered by a gray coat of lichens. the tenacity of the prostrate columns first drew my attention. the builder scant of materials would have experienced no difficulty in finding among them sufficient lintels for apertures from eight to twelve feet in width. i was next struck with the peculiar composition of the stone; it much rather resembles an altered sandstone, in at least the weathered specimens, than a trap, and yet there seemed nothing to indicate that it was an _old red_ sandstone. its columnar structure bore evidence to the action of great heat; and its pale red color was exactly that which the oölitic sandstones of the island, with their slight ochreous tinge, would assume in a common fire. and so i set myself to look for fossils. in the columnar stone itself i expected none, as none occur in vast beds of the unaltered sandstones, out of some one of which i supposed it might possibly have been formed; and none i found: but in a rolled block of altered shale of a much deeper red than the general mass, and much more resembling old red sandstone, i succeeded in detecting several shells, identical with those of the deposit of blue clay described in a former chapter. there occurred in it the small univalve resembling a trochus, together with the oblong bivalve, somewhat like a tellina; and, spread thickly throughout the block, lay fragments of coprolitic matter, and the scales and teeth of fishes. night was coming on, and the tide had risen on the beach; but i hammered lustily, and laid open in the dark red shale a vertebral joint, a rib, and a parallelogramical fragment of solid bone, none of which could have belonged to any fish. it was an interesting moment for the curtain to drop over the promontory of _ru-stoir_; i had thus already found in connection with it well nigh as many reptilian remains as had been found in all scotland before,--for there could exist no doubt that the bones i laid open were such; and still more interesting discoveries promised to await the coming morning, and a less hasty survey. we found a hospitable meal awaiting us at a picturesque old two-story house, with, what is rare in the island, a clump of trees beside it, which rises on the northern angle of the oölitic meniscus; and after our day's hard work in the fresh sea-air, we did ample justice to the viands. dark night had long set in ere we reached our vessel. next day was saturday; and it behooved my friend, the minister,--as scrupulously careful in his pulpit preparations for the islanders of eigg as if his congregation were an edinburgh one,--to remain on board, and study his discourse for the morrow. i found, however, no unmeet companion for my excursion in his trusty mate john stewart. john had not very much english, and i had no gaelic; but we contrived to understand one another wonderfully well; and ere evening i had taught him to be quite as expert in hunting dead crocodiles as myself. we reached the _ru-stoir_, and set hard to work with hammer and chisel. the fragments of red shale were strewed thickly along the shore for at least three quarters of a mile; wherever the red columnar rock appeared, there lay the shale, in water-worn blocks, more or less indurated; but the beach was covered over with shingle and detached masses of rock, and we could nowhere find it _in situ_. a winter storm powerful enough to wash the beach bare might do much to assist the explorer. there is a piece of shore on the eastern coast of scotland, on which for years together i used to pick up nodular masses of lime containing fish of the old red sandstone; but nowhere in the neighborhood could i find the ichthyolite bed in which they had originally formed. the storm of a single night swept the beach; and in the morning the ichthyolites lay revealed _in situ_ under a stratum of shingle which i had a hundred times examined, but which, though scarce a foot in thickness, had concealed from me the ichthyolite bed for five twelvemonths together! wherever the altered shale of _ru-stoir_ has been thrown high on the beach, and exposed to the influences of the weather, we find it fretted over with minute organisms, mostly the scales, plates, bones, and teeth of fishes. the organisms, as is frequently the case, seem indestructible, while the hard matrix in which they are embedded has weathered from around them. some of the scales present the rhomboidal outline, and closely resemble those of the _lepidotus minor_ of the weald; others approximate in shape to an isosceles triangle. the teeth are of various forms: some of them, evidently palatal, are mere blunted protuberances glittering with enamel,--some of them present the usual slim, thorn-like type common in the teeth of the existing fish of our coasts,--some again are squat and angular, and rest on rectilinear bases, prolonged considerably on each side of the body of the tooth, like the rim of a hat or the flat head of a scupper nail. of the occipital plates, some present a smooth enamelled surface, while some are thickly tuberculated,--each tubercle bearing a minute depression in its apex, like a crater on the summit of a rounded hill. we find reptilian bones in abundance,--a thing new to scotch geology,--and in a state of keeping peculiarly fine. they not a little puzzled john stewart: he could not resist the evidence of his senses: they were bones, he said, real bones,--there could be no doubt of that: _there_ were the joints of a backbone, with the hole the brain-marrow had passed through; and _there_ were shank-bones and ribs, and fishes' teeth; but how, he wondered, had they all got into the very heart of the hard red stones? he had seen what was called wood, he said, dug out of the side of the scuir, without being quite certain whether it was wood or no; but there could be no uncertainty here. i laid open numerous vertebræ of various forms,--some with long spinous processes rising over the body or _centrum_ of the bone,--which i found in every instance, unlike that of the ichthyosaurus, only moderately concave on the articulating faces; in others the spinous process seemed altogether wanting. only two of the number bore any mark of the suture which unites, in most reptiles, the annular process to the centrum; in the others both centrum and process seemed anchylosed, as in quadrupeds, into one bone; and there remained no scar to show that the suture had ever existed. in some specimens the ribs seem to have been articulated to the sides of the centrum; in others there is a transverse process, but no marks of articulation. some of the vertebræ are evidently dorsal, some cervical, one apparently caudal; and almost all agree in showing in front two little eyelets, to which the great descending artery seems to have sent out blood-vessels in pairs. the more entire ribs i was lucky enough to disinter have, as in those of crocodileans, double heads; and a part of a fibula, about four inches in length, seems also to belong to this ancient family. a large proportion of the other bones are evidently plesiosaurian. i found the head of the flat humerus so characteristic of the extinct order to which the plesiosaurus has been assigned, and two digital bones of the paddle, that, from their comparatively slender and slightly curved form, so unlike the digitals of its cogener the ichthyosaurus, could have belonged evidently to no other reptile. i observed, too, in the slightly curved articulations of not a few of the vertebræ, the gentle convexity in the concave centre, which, if not peculiar to the plesiosaurus, is at least held to distinguish it from most of its contemporaries. among the various nondescript organisms of the shale, i laid open a smooth angular bone, hollowed something like a grocer's scoop; a three-pronged caltrop-looking bone, that seems to have formed part of a pelvic arch; another angular bone, much massier than the first, regarding the probable position of which i could not form a conjecture, but which some of my geological friends deem cerebral; an extremely dense bone, imperfect at each end, which presents the appearance of a cylinder slightly flattened; and various curious fragments, which, with what our scotch museums have not yet acquired,--entire reptilian fossils for the purposes of comparison,--might, i doubt not, be easily assigned to their proper places. it was in vain that, leaving john to collect the scattered pieces of shale in which the bones occurred, i set myself again and again to discover the bed from which they had been detached. the tide had fallen, and a range of skerries lay temptingly off, scarce a hundred yards from the water's edge: the shale beds might be among them, with plesiosauri and crocodiles stretching entire; and fain would i have swum off to them, as i had done oftener than once elsewhere, with my hammer in my teeth, and with shirt and drawers in my hat; but a tall brown forest of kelp and tangle in which even a seal might drown, rose thick and perilous round both shore and skerries; a slight swell was felting the long fronds together; and i deemed it better, on the whole, that the discoveries i had already made should be recorded, than that they should be lost to geology, mayhap for a whole age, in the attempt to extend them. the water, beautifully transparent, permitted the eye to penetrate into its green depths for many fathoms around, though every object presented, through the agitated surface, an uncertain and fluctuating outline. i could see, however, the pink-colored urchin warping himself up, by his many cables, along the steep rock-sides; the green crab stalking along the gravelly bottom; a scull of small rock-cod darting hither and thither among the tangle-roots; and a few large medusæ slowly flapping their continuous fins of gelatine in the opener spaces, a few inches under the surface. many curious families had their representatives within the patch of sea which the eye commanded; but the strange creatures that had once inhabited it by thousands, and whose bones still lay sepulchred on its shores, had none. how strange, that the identical sea heaving around stack and skerry in this remote corner of the hebrides should have once been thronged by reptile shapes more strange than poet ever imagined,--dragons, gorgons and chimeras! perhaps of all the extinct reptiles, the plesiosaurus was the most extraordinary. an english geologist has described it, grotesquely enough, and yet most happily, as a snake _threaded_ through a tortoise. and here on this very spot, must these monstrous dragons have disported and fed; here must they have raised their little reptile heads and long swan-like necks over the surface, to watch an antagonist or select a victim; here must they have warred and wedded, and pursued all the various instincts of their unknown natures. a strange story, surely, considering it is a true one! i may mention in the passing, that some of the fragments of the shale in which the remains are embedded have been baked by the intense heat into an exceedingly hard, dark-colored stone, somewhat resembling basalt. i must add further, that i by no means determine the rock with which we find it associated to be in reality an altered sandstone. such is the appearance which it presents where weathered; but its general aspect is that of a porphyritic trap. be it what it may, the fact is not at all affected, that the shores, wherever it occurs on this tract of insular coast, are strewed with reptilian remains of the oölite. the day passed pleasantly in the work of exploration and discovery; the sun had already declined far in the west; and, bearing with us our better fossils, we set out, on our return, by the opposite route to that along the bay of laig, which we had now thrice walked over. the grassy talus so often mentioned continues to run on the eastern side of the island for about six miles, between the sea and the inaccessible rampart of precipice behind. it varies in breadth from about two to four hundred yards; the rampart rises over it from three to five hundred feet; and a noble expanse of sea, closed in the distance by a still nobler curtain of blue hills, spreads away from its base: and it was along this grassy talus that our homeward road lay. let the edinburgh reader imagine the fine walk under salisbury crags lengthened some twenty times,--the line of precipices above heightened some five or six times,--the gravelly slope at the base not much increased in altitude, but developed transversely into a green undulating belt of hilly pasture, with here and there a sunny slope level enough for the plough, and here and there a rough wilderness of detached crags and broken banks; let him further imagine the sea sweeping around the base of this talus, with the nearest opposite land--bold, bare and undulating atop--some six or eight miles distant; and he will have no very inadequate idea of the peculiar and striking scenery through which, this evening, our homeward route lay. i have scarce ever walked over a more solitary tract. the sea shuts it in on the one hand, and the rampart of rocks on the other; there occurs along its entire length no other human dwelling than a lonely summer shieling; for full one-half the way we saw no trace of man; and the wildness of the few cattle which we occasionally startled in the hollows showed us that man was no very frequent visitor among them. about half an hour before sunset we reached the midway shieling. rarely have i seen a more interesting spot, or one that, from its utter loneliness, so impressed the imagination. the shieling, a rude low-roofed erection of turf and stone, with a door in the centre some five feet in height or so, but with no window, rose on the grassy slope immediately in front of the vast continuous rampart. a slim pillar of smoke ascends from the roof, in the calm, faint and blue within the shadow of the precipice, but it caught the sunlight in its ascent, and blushed, ere it melted into the ether, a ruddy brown. a streamlet came pouring from above in a long white thread, that maintained its continuity unbroken for at least two-thirds of the way; and then, untwisting into a shower of detached drops, that pattered loud and vehemently in a rocky recess, it again gathered itself up into a lively little stream, and, sweeping past the shieling, expanded in front into a circular pond, at which a few milch cows were leisurely slaking their thirst. the whole grassy talus, with a strip mayhap a hundred yards wide, of deep green sea, lay within the shadow of the tall rampart; but the red light fell, for many a mile beyond, on the glassy surface; and the distant cuchullin hills, so dark at other times, had all their prominent slopes and jutting precipices tipped with bronze; while here and there a mist streak, converted into bright flame, stretched along their peaks or rested on their sides. save the lonely shieling, not a human dwelling was in sight. an island girl of eighteen, more than merely good-looking, though much embrowned by the sun, had come to the door to see who the unwonted visitors might be, and recognized in john stewart an old acquaintance. john informed her in her own language that i was mr. swanson's sworn friend, and not a _moderate_, but one of their own people, and that i had fasted all day, and had come for a drink of milk. the name of her minister proved a strongly recommendatory one: i have not yet seen the true celtic interjection of welcome,--the kindly "o o o,"--attempted on paper; but i had a very agreeable specimen of it on this occasion, _viva voce_. and as she set herself to prepare for us a rich bowl of mingled milk and cream, john and i entered the shieling. there was a turf fire at the one end, at which there sat two little girls, engaged in keeping up the blaze under a large pot, but sadly diverted from their work by our entrance; while the other end was occupied by a bed of dry straw, spread on the floor from wall to wall, and fenced off at the foot by a line of stones. the middle space was occupied by the utensils and produce of the dairy,--flat wooden vessels of milk, a butter-churn, and a tub half-filled with curd; while a few cheeses, soft from the press, lay on a shelf above. the little girls were but occasional visitors, who had come, out of a juvenile frolic, to pass the night in the place; but i was informed by john that the shieling had two other inmates, young women, like the one so hospitably engaged in our behalf, who were out at the milking, and that they lived here all alone for several months every year, when the pasturage was at its best, employed in making butter and cheese for their master, worthy mr. m'donald of keill. they must often feel lonely when night has closed darkly over mountain and sea, or in those dreary days of mist and rain so common in the hebrides, when nought may be seen save the few shapeless crags that stud the nearer hillocks around them, and nought heard save the moaning of the wind in the precipices above, or the measured dash of the wave on the wild beach below. and yet they would do ill to exchange their solitary life and rude shieling for the village dwellings and gregarious habits of the females who ply their rural labors in bands among the rich fields of the lowlands, or for the unwholesome backroom and weary task-work of the city seamstress. the sunlight was fading from the higher hill-tops of skye and glenelg as we bade farewell to the lonely shieling and the hospitable island girl. the evening deepened as we hurried southwards along the scarce visible pathway, or paused for a few seconds to examine some shattered block, bulky as a highland cottage, that had fallen from the precipice above. now that the whole landscape lay equally in shadow, one of the more picturesque peculiarities of the continuous rampart came out more strongly as a feature of the scene than when a strip of shade rested along the face of the rock, imparting to it a retiring character, and all was sunshine beyond. a thick bed of white sandstone, as continuous as the rampart itself, runs nearly horizontally about midway in the precipice for mile after mile, and, standing out in strong contrast with the dark-colored trap above and below, reminds one of a belt of white hewn work in a basalt house front, or rather,--for there occurs above a second continuous strip, of an olive hue, the color assumed, on weathering by a bed of amygdaloid,--of a piece of dingy old-fashioned furniture, inlaid with one stringed belt of bleached holly, and another of faded green-wood. at some of the more accessible points i climbed to the line of white belting, and found it to consist of the same soft quartzy sandstone that in the bay of laig furnishes the musical sand. lower down there occur, alternating with the trap, beds of shale and of blue clay, but they are lost mostly in the talus. ill adapted to resist the frosts and rains of winter, their exposed edges have mouldered into a loose soil, now thickly covered over with herbage; and, but for the circumstance that we occasionally find them laid bare by a water-course, we would scarce be aware of their existence at all. the shale exhibits everywhere, as on the opposite side of the _ru-stoir_, faint impressions of a minute shell resembling a cyclas, and ill-preserved fragments of fish-scales. the blue clay i found at one spot where the pathway had cut deep into the hill-side, richly charged with bivalves of the species i had seen so abundant in the resembling clay of the bay of laig; but the closing twilight prevented me from ascertaining whether it also contained the characteristic univalves of the deposit, and whether its shells,--for they seem identical with those of the altered shales of the _ru-stoir_,--might not be associated, like these, with reptilian remains. night fell fast, and the streaks of mist that had mottled the hills at sunset began to spread gray over the heavens in a continuous curtain; but there was light enough left to show me that the trap became more columnar as we neared our journey's end. one especial jutting in the rock presented in the gloom the appearance of an ancient portico, with pediment and cornice, such as the traveller sees on the hill-sides of petræa in front of some old tomb; but it may possibly appear less architectural by day. at length, passing from under the long line of rampart, just as the stars that had begun to twinkle over it were disappearing, one after one, in the thickening vapor, we reached the little bay of kildonan, and found the boat waiting us on the beach. my friend the minister, as i entered the cabin, gathered up his notes from the table, and gave orders for the tea-kettle; and i spread out before him--a happy man--an array of fossils new to scotch geology. no one not an enthusiastic geologist or a zealous roman catholic can really know how vast an amount of interest may attach to a few old bones. has the reader ever heard how fossil relics once saved the dwelling of a monk, in a time of great general calamity, when all his other relics proved of no avail whatever? thomas campbell, when asked for a toast in a society of authors, gave the memory of napoleon bonaparte; significantly adding, "he once hung a bookseller." on a nearly similar principle i would be disposed to propose among geologists a grateful bumper in honor of the revolutionary army that besieged maestricht. that city, some seventy-five or eighty years ago, had its zealous naturalist in the person of m. hoffmann, a diligent excavator in the quarries of st. peter's mountain, long celebrated for its extraordinary fossils. geology, as a science, had no existence at the time; but hoffmann was doing, in a quiet way, all he could to give it a beginning;--he was transferring from the rock to his cabinet, shells, and corals, and crustacea, and the teeth and scales of fishes, with now and then the vertebræ, and now and then the limb-bone, of a reptile. and as he honestly remunerated all the workmen he employed, and did no manner of harm to any one, no one heeded him. on one eventful morning, however, his friends the quarriers laid bare a most extraordinary fossil,--the occipital plates of an enormous saurian, with jaws four and a half feet long, bristling over with teeth, like _chevaux de frise_; and after hoffmann, who got the block in which it lay embedded, cut out entire, and transferred to his house, had spent week after week in painfully relieving it from the mass, all maestricht began to speak of it as something really wonderful. there is a cathedral on st. peter's mountain,--the mountain itself is church-land; and the lazy canon, awakened by the general talk, laid claim to poor hoffmann's wonderful fossil as _his_ property. he was lord of the manor, he said, and the mountain and all that it contained belonged to him. hoffmann defended his fossil as he best could in an expensive lawsuit; but the judges found the law clean against him; the huge reptile head was declared to be "treasure trove" escheat to the lord of the manor; and hoffmann, half broken-hearted, with but his labor and the lawyer's bills for his pains, saw it transferred by rude hands from its place in his museum, to the residence of the grasping churchman. the huge fossil head experienced the fate of dr. chalmer's two hundred churches. hoffmann was a philosopher, however, and he continued to observe and collect as before; but he never found such another fossil; and at length, in the midst of his ingenious labors, the vital energies failed within him, and he broke down and died. the useless canon lived on. the french revolution broke out; the republican army invested maestricht; the batteries were opened; and shot and shell fell thick on the devoted city. but in one especial quarter there alighted neither shot nor shell. all was safe around the canon's house. ordinary relics would have availed him nothing in the circumstances,--no, not "the three kings of cologne," had he possessed the three kings entire, or the jaw-bones of the "eleven thousand virgins;" but there was virtue in the jaw-bones of the mosasaurus, and safety in their neighborhood. the french _savans_, like all the other _savans_ of europe, had heard of hoffmann's fossil, and the french artillery had been directed to play wide of the place where it lay. maestricht surrendered; the fossil was found secreted in a vault, and sent away to the _jardin des plantes_ at paris, maugre the canon, to delight there the heart of cuvier; and the french, generously addressing themselves to the heirs of hoffmann as its legitimate owners, made over to them a considerable sum of money as its price. they reversed the finding of the maestricht judges; and all save the monks of st. peter's have acquiesced in the justice of the decision. chapter vi. something for non-geologists--man destructive--a better and last creation coming--a rainy sabbath--the meeting house--the congregation--the sermon in gaelic--the old wondrous story--the drunken minister of eigg--presbyterianism without life--dr. johnson's account of the conversion of the people of rum--romanism at eigg--the two boys--the freebooter of eigg--voyage resumed--the homeless minister--harbor of isle ornsay--interesting gneiss deposit--a norwegian keep--gneiss at knock--curious chemistry--sea-cliffs beyond portsea--the goblin luidag--scenery of skye. i reckon among my readers a class of non-geologists, who think my geological chapters would be less dull if i left out the geology; and another class of semi-geologists, who say there was decidedly too much geology in my last. with the present chapter, as there threatens to be an utter lack of science in the earlier half of it, and very little, if any, in the latter half, i trust both classes may be in some degree satisfied. it will bear reference to but the existing system of things,--assuredly not the last of the consecutive creations,--and to a species of animal that, save in the celebrated guadaloupe specimens, has not yet been found locked up in stone. there have been much of violence and suffering in the old immature stages of being,--much, from the era of the holoptychius, with its sharp murderous teeth and strong armor of bone, down to that of the cannibal ichthyosaurus, that bears the broken remains of its own kind in its bowels,--much, again, from the times of the crocodile of the oölite, down to the times of the fossil hyena and gigantic shark of the tertiary. nor, i fear, have matters greatly improved in that latest-born creation in the series, that recognizes as its delegated lord the first tenant of earth accountable to his maker. but there is a better and a last creation coming, in which man shall re-appear, not to oppress and devour his fellow-men, and in which there shall be no such wrongs perpetrated as it is my present purpose to record,--"new heavens and a new earth, wherein dwelleth righteousness." well sung the ayrshire ploughman, when musing on the great truth that the present scene of being "is surely not the last,"--a truth corroborated since his day by the analogies of a new science,-- "the poor, oppressed, honest man, had never sure been born, had not there been some recompense to comfort those that mourn." it was sabbath, but the morning rose like a hypochondriac wrapped up in his night-clothes,--gray in fog, and sad with rain. the higher grounds of the island lay hid in clouds, far below the level of the central hollow; and our whole prospect from the deck was limited to the nearer slopes, dank, brown, and uninhabited, and to the rough black crags that frown like sentinels over the beach. now the rime thickened as the rain pattered more loudly on the deck; and even the nearer stacks and precipices showed as unsolid and spectral in the cloud as moonlight shadows thrown on a ground of vapor; anon it cleared up for a few hundred yards, as the shower lightened; and then there came in view, partially at least, two objects that spoke of man,--a deserted boat harbor, formed of loosely piled stone, at the upper extremity of a sandy bay; and a roofless dwelling beside it, with two ruinous gables rising over the broken walls. the entire scene suggested the idea of a land with which man had done for ever;--the vapor-enveloped rocks,--the waste of ebb-uncovered sand,--the deserted harbor,--the ruinous house,--the melancholy rain-fretted tides eddying along the strip of brown tangle in the foreground,--and, dim over all, the thick, slant lines of the beating shower!--i know not that of themselves they would have furnished materials enough for a finished picture in the style of hogarth's "end of all things;" but right sure am i that in the hands of bewick they would have been grouped into a tasteful and poetic vignette. we set out for church a little after eleven,--the minister encased in his ample-skirted storm-jacket of oiled canvas, and protected atop by a genuine _sou-wester_, of which the broad posterior rim eloped half a yard down his back; and i closely wrapped up in my gray maud, which proved, however, a rather indifferent protection against the penetrating powers of a true hebridean drizzle. the building in which the congregation meets is a low dingy cottage of turf and stone, situated nearly opposite to the manse windows. it had been built by my friend, previous to the disruption, at his own expense, for a gaelic school, and it now serves as a place of worship for the people. we found the congregation already gathered, and that the very bad morning had failed to lessen their numbers. there were a few of the male parishioners keeping watch at the door, looking wistfully out through the fog and rain for their minister; and at his approach nearly twenty more came issuing from the place,--like carder bees from their nest of dried grass and moss,--to gather round him, and shake him by the hand. the islanders of eigg are an active, middle-sized race, with well-developed heads, acute intellects, and singularly warm feelings. and on this occasion at least there could be no possibility of mistake respecting the feelings with which they regarded their minister. rarely have i seen human countenances so eloquently vocal with veneration and love. the gospel message, which my friend had been the first effectually to bring home to their hearts,--the palpable fact of his sacrifice for the sake of the high principles which he has taught,--his own kindly disposition,--the many services which he has rendered them, for not only has he been the minister, but also the sole medical man, of the small isles, and the benefit of his practice they have enjoyed, in every instance, without fee or reward,--his new life of hardship and danger, maintained for their sakes amid sinking health and great privation,--their frequent fears for his safety when stormy nights close over the sea,--and they have seen his little vessel driven from her anchorage, just as the evening has fallen,--all these are circumstances that have concurred in giving him a strong hold on their affections. the rude turf-building we found full from end to end, and all a-steam with a particularly wet congregation, some of whom, neither very robust nor young, had travelled in the soaking drizzle from the farther extremities of the island. and, judging from the serious attention with which they listened to the discourse, they must have deemed it full value for all it cost them. i have never yet seen a congregation more deeply impressed, or that seemed to follow the preacher more intelligently; and i was quite sure, though ignorant of the language in which my friend addressed them, that he preached to them neither heresy nor nonsense. there was as little of the reverence of externals in the place as can well be imagined: an uneven earthen floor,--turf-walls on every side, and a turf-roof above,--two little windows of four panes a-piece, adown which the rain-drops were coursing thick and fast,--a pulpit grotesquely rude, that had never employed the bred carpenter,--and a few ranges of seats of undressed deal, such were the mere materialisms of this lowly church of the people; and yet here, notwithstanding, was the living soul of a christian community,--understandings convinced of the truth of the gospel, and hearts softened and impressed by its power. my friend, at the conclusion of his discourse, gave a brief digest of its contents in english, for the benefit of his one saxon auditor; and i found, as i had anticipated, that what had so moved the simple islanders was just the old wondrous story, which, though repeated and re-repeated times beyond number, from the days of the apostles till now, continues to be as full of novelty and interest as ever,--"god so loved the world, that he gave his only begotten son, that whosoever believeth on him should not perish, but have everlasting life." the great truths which had affected many of these poor people to tears, were exactly those which, during the last eighteen hundred years, have been active in effecting so many moral revolutions in the world, and which must ultimately triumph over all error and all oppression. on this occasion, as on many others, i had to regret my want of gaelic. it was my misfortune to miss being born to this ancient language, by barely a mile of ferry. i first saw light on the southern shore of the frith of cromarty, where the strait is narrowest, among an old established lowland community, marked by all the characteristics, physical and mental, of the lowlanders of the southern districts; whereas, had i been born on the northern shore, i would have been brought up among a celtic tribe, and gaelic would have been my earliest language. thus distinct was the line between the two races preserved, even after the commencement of the present century. in returning to the betsey during the mid-day interval in the service, we passed the ruinous two-gabled house beside the boat-harbor. during the incumbency of my friend's predecessor, it had been the public-house of the island, and the parish minister was by far its best customer. he was in the practice of sitting in one of its dingy little rooms, day after day, imbibing whisky and peat-reek; and his favorite boon companion on these occasions was a roman catholic tenant who lived on the opposite side of the island, and who, when drinking with the minister, used regularly to fasten his horse beside the door, till at length all the parish came to know that when the horse was standing outside the minister was drinking within. in course of time, through the natural gravitation operative in such cases, the poor incumbent became utterly scandalous, and was libelled for drunkenness before the general assembly; but, as the island of eigg lies remote from observation, evidence was difficult to procure; and had not the infatuated man got senselessly drunk one evening, when in edinburgh on his trial, and staggered, of all places in the world, into the general assembly, he would probably have died minister of eigg. as the event happened, however, the testimony thus unwittingly furnished in the face of the court that tried him was deemed conclusive;--he was summarily deposed from his office, and my friend succeeded him. presbyterianism without the animating life is a poor shrunken thing: it never lies in state when it is dead; for it has no body of fine forms, or trapping of imposing ceremonies, to give it bulk or adornment: without the vitality of evangelism it is nothing; and in this low and abject state my friend found the presbyterianism of eigg. his predecessor had done it only mischief; nor had it been by any means vigorous before. rum is one of the four islands of the parish; and all my readers must be familiar with dr. johnson's celebrated account of the conversion to protestantism of the people of rum. "the inhabitants," says the doctor, in his "journey to the western islands," "are fifty-eight families, who continued papists for some time after the laird became a protestant. their adherence to their old religion was strengthened by the countenance of the laird's sister, a zealous romanist; till one sunday, as they were going to mass under the conduct of their patroness, maclean met them on the way, gave one of them a blow on the head with a yellow stick,--i suppose a cane, for which the erse had no name, and drove them to the kirk, from which they have never departed. since the use of this method of conversion, the inhabitants of eigg and canna who continue papists call the protestantism of rum the religion of the yellow stick." now, such was the kind of protestantism that, since the days of dr. johnson, had also been introduced, i know not by what means, into eigg. it had lived on the best possible terms with the popery of the island; the parish minister had soaked day after day in the public-house with a roman catholic boon companion; and when a papist man married a protestant woman, the woman, as a matter of course, became papist also; whereas, when it was the man who was a protestant, and the woman a papist, the woman remained what she had been. roman catholicism was quite content with terms, actual though not implied, of a kind so decidedly advantageous; and the roman catholics used good-humoredly to urge on their neighbors the protestants, that, as it was palpable they had no religion of any kind, they had better surely come over to them, and have some. in short, all was harmony between the two churches. my friend labored hard, as a good and honest man ought, to impart to protestantism in his parish the animating life of the reformation; and, through the blessing of god, after years of anxious toil, he at length fully succeeded. i had got wet, and the day continued bad; and so, instead of returning to the evening sermon, which began at six, i remained alone aboard of the vessel. the rain ceased in little more than an hour after, and in somewhat more than two hours i got up on deck to see whether the congregation was not dispersing, and if it was not yet time to hang on the kettle for our evening tea. the unexpected apparition of some one aboard the free church yacht startled two ragged boys who were manoeuvring a little boat a stone-cast away, under the rocky shores of _eilean chaisteil_, and who, on catching a glimpse of me, flung themselves below the thwarts for concealment. an oar dropped into the water; there was a hasty arm and half a head thrust over the gunwale to secure it; and then the urchin to whom they belonged again disappeared. meanwhile the boat drifted slowly away: first one little head would appear for a moment over the gunwale, then another, as if reconnoitering the enemy; but i still kept my place on deck; and at length, tired out, the ragged little crew took to their oars, and rowed into a shallow bay at the lower extremity of the glebe, with a cottage, in size and appearance much resembling an ant-hill, peeping out at its inner extremity among some stunted bushes. i had marked the place before, and had been struck with the peculiarity of the choice that could have fixed on it as a site for a dwelling: it is at once the most inconvenient and picturesque on this side the island. a semi-circular line of columnar precipices, that somewhat resembles an amphitheatre turned outside in,--for the columns that overlook the area are quite as lofty as those which should form the amphitheatre's outer wall,--sweeps round a little bay, flat and sandy at half-tide, but bordered higher up by a dingy, scarce passable beach of columnar fragments that have toppled from above. between the beach and the line of columns there is a bosky talus, more thickly covered with brushwood than is at all common in the hebrides, and scarce more passable than the rough beach at its feet. and at the bottom of this talus, with its one gable buried in the steep ascent,--for there is scarce a foot-breadth of platform between the slope and the beach,--and with the other gable projected to the tide-line on rugged columnar masses, stands the cottage. the story of the inmate,--the father of the two ragged boys,--is such a one as crabbe would have delighted to tell, and as he could have told better than any one else. he had been, after a sort, a freebooter in his time, but born an age or two rather late; and the law had proved over strong for him. on at least one occasion, perhaps oftener,--for his adventures are not all known in eigg,--he had been in prison for sheep-stealing. he had the dangerous art of subsisting without the ostensible means, and came to be feared and avoided by his neighbors as a man who lived on them without asking their leave. with neither character nor a settled way of living, his wits, i am afraid, must have been often whetted by his necessities: he stole lest he should starve. for some time he had resided in the adjacent island of muck; but, proving a bad tenant, he had been ejected by the agent of the landlord, i believe a very worthy man, who gave him half a boll of meal to get quietly rid of him, and pulled down his house, when he had left the island, to prevent his return. betaking himself, with his boys, to a boat, he set out in quest of some new lodgment. he made his first attempt or two on the mainland, where he strove to drive a trade in begging, but he was always recognized as the convicted sheep-stealer, and driven back to the shore. at length, after a miserable term of wandering, he landed in the winter season on eigg, where he had a grown-up son, a miller; and, erecting a wretched shed with some spars and the old sail of a boat placed slantways against the side of a rock, he squatted on the beach, determined, whether he lived or died, to find a home on the island. the islanders were no strangers to the character of the poor forlorn creature, and kept aloof from him,--none of them, however, so much as his own son; and, for a time, my friend the minister, aware that he had been the pest of every community among which he had lived, stood aloof from him too, in the hope that at length, wearied out, he might seek for himself a lodgment elsewhere. there came on, however, a dreary night of sleet and rain, accompanied by a fierce storm from the sea; and intelligence reached the manse late in the evening, that the wretched sheep-stealer had been seized by sudden illness, and was dying on the beach. there could be no room for further hesitation in this case; and my friend the minister gave instant orders that the poor creature should be carried to the manse. the party, however, which he had sent to remove him found the task impracticable. the night was pitch dark; and the road, dangerous with precipices, and blocked up with rough masses of rock and stone, they found wholly impassable with so helpless a burden. and so, administering some cordials to the poor, hapless wretch, they had to leave him in the midst of the storm, with the old wet sail flapping about his ears, and the half-frozen rain pouring in upon him in torrents. he must have passed a miserable night, but it could not have been a whit more miserable than that passed by the minister in the manse. as the wild blast howled around his comfortable dwelling, and shook the casements as if some hand outside were assaying to open them, or as the rain pattered sharp and thick on the panes, and the measured roar of the surf rose high over every other sound, he could think of only the wretched creature exposed to the fury of a tempest so terrible, as perchance wrestling in his death agony in the darkness beside the breaking wave, or as already stiffening on the shore. he was early astir next morning, and almost the first person he met was the poor sheep-stealer, looking more like a ghost than a living man. the miserable creature had mustered strength enough to crawl up from the beach. my friend has often met better men with less pleasure. he found a shelter for the poor outcast; he tended him, prescribed for him, and, on his recovery, gave him leave to build for himself the hovel at the foot of the crags. the islanders were aware they had got but an indifferent neighbor through the transaction, though none of them, with the exception of the poor creature's son, saw what else their minister could have done in the circumstances. but the miller could sustain no apology for the arrangement that had given him his vagabond father as a neighbor; and oftener than once the site of the rising hovel became a scene of noisy contention between parent and son. some of the islanders informed me that they had seen the son engaged in pulling down the stones of the walls as fast as the father raised them up; and, save for the interference of the minister, the hut, notwithstanding the permission he gave, would scarce have been built. on the morning of monday we unloosed from our moorings, and set out with a light variable breeze for isle ornsay, in skye, where the wife and family of mr. swanson resided, and from which he had now been absent for a full month. the island diminished, and assumed its tint of diluting blue, that waxed paler and paler hour after hour, as we left it slowly behind us; and the scuir, projected boldly from its steep hill-top, resembled a sharp hatchet-edge presented to the sky. "nowhere," said my friend, "did i so thoroughly realize the disruption of last year as at this spot. i had just taken my last leave of the manse; mrs. swanson had staid a day behind me in charge of a few remaining pieces of furniture, and i was bearing some of the rest, and my little boy bill, scarce five years of age at the time, in the yacht with me to skye. the little fellow had not much liked to part from his mother, and the previous unsettling of all sorts of things in the manse had bred in him thoughts he had not quite words to express. the further change to the yacht, too, he had deemed far from an agreeable one. but he had borne up, by way of being very manly; and he seemed rather amused that papa should now have to make his porridge for him, and to put him to bed, and that it was john stewart, the sailor, who was to be the servant girl. the passage, however, was tedious and disagreeable; the wind blew a-head, and heart and spirits failing poor bill, and somewhat sea-sick to boot, he lay down on the floor, and cried bitterly to be taken home. 'alas, my boy!' i said, 'you have no home now: your father is like the poor sheep-stealer whom you saw on the shore of eigg.' this view of matters proved in no way consolatory to poor bill. he continued his sad wail, 'home, home, home!' until at length he fairly sobbed himself asleep; and i never, on any other occasion, so felt the desolateness of my condition as when the cry of my boy,--'home, home, home!'--was ringing in my ears." we passed, on the one hand, loch nevis and loch hourn, two fine arms of the sea that run far into the mainland, and open up noble vistas among the mountains; and, on the other, the long undulating line of sleat in skye, with its intermingled patches of woodland and arable on the coast, and its mottled ranges of heath and rock above. towards evening we entered the harbor of isle ornsay, a quiet, well-sheltered bay, with a rocky islet for a breakwater on the one side, and the rudiments of a highland village, containing a few good houses, on the other. half a dozen small vessels were riding at anchor, curtained round, half-mast high, with herring nets; and a fleet of herring-boats lay moored beside them a little nearer the shore. there had been tolerable takes for a few nights in the neighboring sea, but the fish had again disappeared, and the fishermen, whose worn-out tackle gave such evidence of a long-continued run of ill-luck, as i had learned to interpret on the east coast, looked gloomy and spiritless, and reported a deficient fishery. i found mrs. swanson and her family located in one of the two best houses in the village, with a neat enclosure in front, and a good kitchen-garden behind. the following day i spent in exploring the rocks of the district,--a primary region with regard to organic existence, "without _form_ and void." from isle ornsay to the point of sleat, a distance of thirteen miles, gneiss is the prevailing deposit; and in no place in the district are the strata more varied and interesting than in the neighborhood of knockhouse, the residence of mr. elder, which i found pleasingly situated at the bottom of a little open bay, skirted with picturesque knolls partially wooded, that present to the surf precipitous fronts of rock. one insulated eminence, a gun-shot from the dwelling-house, that presents to the sea two mural fronts of precipice, and sinks in steep grassy slopes on two sides more, bears atop a fine old ruin. there is a blind-fronted massy keep, wrapped up in a mantle of ivy, perched at the one end, where the precipice sinks steepest; while a more ruinous though much more modern pile of building, perforated by a double row of windows, occupies the rest of the area. the square keep has lost its genealogy in the mists of the past, but a vague tradition attributes its erection to the norwegians. the more modern pile is said to have been built about three centuries ago by a younger son of m'donald of the isles; but it is added that, owing to the jealousy of his elder brother, he was not permitted to complete or inhabit it. i find it characteristic of most highland traditions, that they contain speeches: they constitute true oral specimens of that earliest and rudest style of historic composition in which dialogue alternates with narrative. "my wise brother is building a fine house," is the speech preserved in this tradition as that of the elder son: "it is rather a pity for himself that he should be building it on another man's lands." the remark was repeated to the builder, says the story, and at once arrested the progress of the work. mr. elder's boys showed me several minute pieces of brass, somewhat resembling rust-eaten coin, that they had dug out of the walls of the old keep; but the pieces bore no impress of the dye, and seemed mere fragments of metal beaten thin by the hammer. the gneiss at knock is exceedingly various in its composition, and many of its strata the geologist would fail to recognize as gneiss at all. we find along the precipices its two unequivocal varieties, the schistose and the granitic, passing not unfrequently, the former into a true mica schist, the latter into a pale feldspathose rock, thickly pervaded by needle-like crystals of tremolite, that, from the style of the grouping, and the contrast existing between the dark green of the enclosed mineral, and the pale flesh-color of the ground, frequently furnishes specimens of great beauty. in some pieces the tremolite assumes the common fan-like form; in some, the crystals, lying at nearly right angles with each other, present the appearance of ancient characters inlaid in the rock; in some they resemble the footprints of birds in a thin layer of snow; and in one curious specimen picked up by mr. swanson, in which a dark linear strip is covered transversely by crystals that project thickly from both its sides, the appearance presented is that of a minute stigmaria of the coal measures, with the leaves, still bearing their original green color, bristling thick around it. mr. elder showed me, intercalated among the gneiss strata of a little ravine in the neighborhood of isle ornsay, a thin band of a bluish-colored indurated clay, scarcely distinguishable, in the hand specimen, from a weathered clay-stone, but unequivocally a stratum of the rock. i have found the same stone existing, in a decomposed state, as a very tenacious clay, among the gneiss strata of the hill of cromarty; and oftener than once had i amused myself in fashioning it, with tolerable success, into such rude pieces of pottery as are sometimes found in old sepulchral tumuli. such are a few of the rocks included in the general gneiss deposit of sleat. if we are to hold, with one of the most distinguished of living geologists, that the stratified primary rocks are aqueous deposits altered by heat, to how various a chemistry must they not have been subjected in this district! in one stratum, so softened that all its particles were disengaged to enter into new combinations, and yet not so softened but that it still maintained its lines of division from the strata above and below, the green tremolite was shooting its crystals into the pale homogeneous mass; while in another stratum the quartz drew its atoms apart in masses that assumed one especial form, the feldspar drew its atoms apart into masses that assumed another and different form, and the glittering mica built up its multitudinous layers between. here the unctuous chlorite constructed its soft felt; there the micaceous schist arranged its undulating layers; yonder the dull clay hardened amid the intense heat, but, when all else was changing, retained its structure unchanged. surely a curious chemistry, and conducted on an enormous scale! it had been an essential part of my plan to explore the splendid section of the lower oölite furnished by the line of sea-cliffs that, to the north of the portree, rise full seven hundred feet over the beach; and on the morning of wednesday i set out with this intention from isle ornsay, to join the mail gig at broadford, and pass on to portree,--a journey of rather more than thirty miles. i soon passed over the gneiss, and entered on a wide deposit, extending from side to side of the island, of what is generally laid down in our geological maps as old red sandstone, but which, in most of its beds, quite as much resembles a quartz rock, and which, unlike any old red proper i have ever seen, passes, by insensible gradations, into the gneiss.[ ] wherever it has been laid bare in flat tables among the heath, we find it bearing those mysterious scratches on a polished surface which we so commonly find associated on the mainland with the boulder clay; but here, as in the hebrides generally, the boulder clay is wanting. to the tract of red sandstone there succeeds a tract of lias, which, also extending across the island, forms by far the most largely-developed deposit of this formation in scotland. it occupies a flat dingy valley, about six miles in length, and that varies from two to four miles in breadth. the dreary interior is covered with mosses, and studded with inky pools, in which the botanist finds a few rare plants, and which were dimpled, as i passed them this morning, with countless eddies, formed by myriads of small quick glancing trout, that seemed busily engaged in fly-catching. the rock appears but rarely,--all is moss, marsh, and pool; but in a few localities on the hill-sides, where some stream has cut into the slope, and disintegrated the softer shales, the shepherd finds shells of strange form strewed along the water-courses, or bleaching white among the heath. the valley,--evidently a dangerous one to the night traveller, from its bogs and its tarns,--is said to be haunted by a spirit peculiar to itself,--a mischievous, eccentric, grotesque creature, not unworthy, from the monstrosity of its form, of being associated with the old monsters of the lias. luidag--for so the goblin is called--has but one leg, terminating, like an ancient satyr's, in a cloven foot; but it is furnished with two arms, bearing hard fists at the end of them, with which it has been known to strike the benighted traveller in the face, or to tumble him over into some dark pool. the spectre may be seen at the close of evening hopping vigorously among the distant bogs, like a felt ball on its electric platform; and when the mist lies thick in the hollows, an occasional glimpse may be caught of it even by day. but when i passed the way there was no fog: the light, though softened by a thin film of cloud, fell equally over the heath, revealing hill and hollow; and i was unlucky enough not to see this goblin of the liasic valley. a deep indentation of the coast, which forms the bay of broadford, corresponds with the hollow of the valley. it is simply a portion of the valley itself occupied by the sea; and we find the lias, from its lower to its upper beds, exposed in unbroken series along the beach. in the middle of the opening lies the green level island of pabba, altogether composed of this formation, and which, differing, in consequence, both in outline and color, from every neighboring island and hill, seems a little bit of flat fertile england, laid down, as if for contrast's sake, amid the wild rough hebrides. of pabba and its wonders, however, more anon. i explored a considerable range of shore along the bay; but as i made it the subject of two after explorations ere i mastered its deposits, i shall defer my description till a subsequent chapter. it was late this evening ere the post-gig arrived from the south, and the night and several hours of the following morning were spent in travelling to portree. i know not, however, that i could have seen some of the wildest and most desolate tracts in skye to greater advantage. there was light enough to show the bold outlines of the hills,--lofty, abrupt, pyramidal,--just such hills, both in form and grouping, as a profile in black showed best; a low blue vapor slept in the calm over the marshes at their feet; the sea, smooth as glass, reflected the dusk twilight gleam in the north, revealing the narrow sounds and deep mountain-girdled lochs along which we passed; gray crags gleamed dimly on the sight; birch-feathered acclivities presented against sea and sky their rough bristly edges; all was vast, dreamy, obscure, like one of martin's darker pictures: the land of the seer and the spectre could not have been better seen. morning broke dim and gray, while we were yet several miles from portree; and i reached the inn in time to see from my bed-room windows the first rays of the rising sun gleaming on the hill-tops. chapter vii. exploration resumed--geology of rasay--an illustration--storr of skye--from portree to holm--discovery of fossils--an island rain--sir r. murchison--labor of drawing a geological line--three edinburgh gentlemen--_prosopolepsia_--wrong surmises corrected--the mail gig--the portree postmaster--isle ornsay--an old acquaintance--reminiscences--a run for rum--"semi-fossil madeira"--idling on deck--prognostics of a storm--description of the gale--loch scresort--the minister's lost _sou-wester_--the free church gathering--the weary minister. i breakfasted in the travellers' room with three gentlemen from edinburgh; and then, accompanied by a boy, whom i had engaged to carry my bag, set out to explore. the morning was ominously hot and breathless; and while the sea lay moveless in the calm, as a floor of polished marble, mountain and rock, and distant island, seemed tremulous all over, through a wavy medium of thick rising vapor. i judged from the first that my course of exploration for the day was destined to terminate abruptly; and as my arrangements with mr. swanson left me, for this part of the country, no second day to calculate upon, i hurried over deposits which in other circumstances i would have examined more carefully,--content with a glance. accustomed in most instances to take long aims, as cuddy headrig did, when he steadied his musket on a rest behind the hedge, and sent his ball through laird oliphant's forehead, i had on this occasion to shoot flying; and so, selecting a large object for a mark, that i might run the less risk of missing, i strove to acquaint myself rather with the general structure of the district than with the organisms of its various fossiliferous beds. the long narrow island of rasay lies parallel to the coast of skye, like a vessel laid along a wharf, but drawn out from it as if to suffer another vessel of the same size to take her berth between; and on the eastern shores of both skye and rasay we find the same oölitic deposits tilted up at nearly the same angle. the section presented on the eastern coast of the one is nearly a duplicate of the section presented on the eastern coast of the other. during one of the severer frosts of last winter i passed along a shallow pond, studded along the sides with boulder stones. it had been frozen over; and then, from the evaporation so common in protracted frosts, the water had shrunk, and the sheet of ice which had sunk down over the central portion of the pond exhibited what a geologist would term very considerable marks of disturbance among the boulders at the edges. over one sharp-backed boulder there lay a sheet tilted up like the lid of a chest half-raised; and over another boulder immediately behind it there lay another uptilted sheet, like the lid of a second half-open chest; and in both sheets, the edges, lying in nearly parallel lines, presented a range of miniature cliffs to the shore. now, in the two uptilted ice-sheets of this pond i recognized a model of the fundamental oölitic deposits rasay and skye. the mainland of scotland had its representative in the crisp snow-covered shore of the pond, with its belt of faded sedges; the place of rasay was indicated by the inner, that of skye by the outer boulder; while the ice-sheets, with their shoreward-turned line of cliffs, represented the oölitic beds, that turn to the mainland their dizzy range of precipices, varying from six to eight hundred feet in height, and then, sloping outwards and downwards, disappear under mountain wildernesses of overlying trap. and it was along a portion of the range of cliff that forms the outermost of the two uptilted lines, and which presents in this district of skye a frontage of nearly twenty continuous miles to the long sound of rasay, that my to-day's course of exploration lay. from the top of the cliff the surface slopes downwards for about two miles into the interior, like the half-raised chest-lid of my illustration sloping towards the hinges, or the uptilted ice-table of the boulder sloping towards the centre of the pond; and the depression behind forms a flat moory valley, full fifteen miles in length, occupied by a chain of dark bogs and treeless lochans. a long line of trap-hills rises over it, in one of which, considerably in advance of the others, i recognized the storr of skye, famous among lovers of the picturesque for its strange group of mingled pinnacles and towers; while directly crossing into the valley from the sound, and then running southwards for about two miles along its bottom, is the noble sea-arm, loch portree, in which, as indicated by the name (the king's port) a scottish king of the olden time, in his voyage round his dominions, cast anchor. the opening of the loch is singularly majestic;--the cliffs tower high on either side in graceful magnificence: but from the peculiar inward slope of the land, all within, as the loch reaches the line of the valley, becomes tame and low, and a black dreary moor stretches from the flat terminal basin into the interior. the opening of loch portree is a palace gateway, erected in front of some homely suburb, that occupies the place which the palace itself should have occupied. there was, however, no such mixture of the homely and the magnificent in the route i had selected to explore. it lay under the escarpment of the cliff; and i purposed pursuing it from portree to holm, a distance of about six miles, and then returning by the flat interior valley. on the one hand rose a sloping rampart, full seven hundred feet in height, striped longitudinally with alternating bands of white sandstone and dark shale, and capped atop by a continuous coping of trap, that lacked not massy tower, and overhanging turret, and projecting sentry-box; while, on the other hand, spreading outwards in the calm from the line of dark trap-rocks below, like a mirror from its carved frame of black oak, lay the sound of rasay, with its noble background of island and main rising bold on the east, and its long mountain vista opening to the south. the first fossiliferous deposit which gave me occasion this morning to use my hammer occurs near the opening of the loch, beside an old celtic burying-ground, in the form of a thick bed of hard sandstone, charged with belemnites,--a bed that must at one time have existed as a widely-spread accumulation of sand,--the bottom, mayhap, of some extensive bay of the oölite, resembling the loch portree of the present day, in which eddy tides deposited the sand swept along by the tidal currents of some neighboring sound, and which swarmed as thickly with cephalopoda as the loch swarmed this day with minute purple-tinged medusæ. i found detached on the shore, immediately below this bed, a piece of calcareous fissile sandstone, abounding in small sulcated terebratulæ, identical, apparently, with the terebratula of a specimen in my collection from the inferior oölite of yorkshire. a colony of this delicate brachiopod must have once lain moored near this spot, like a fleet of long-prowed galleys at anchor, each one with its cable of many strands extended earthwards from the single _dead-eye_ in its umbone. for a full mile after rounding the northern boundary of the loch, we find the immense escarpment composed from top to bottom exclusively of trap; but then the oölite again begins to appear, and about two miles further on the section becomes truly magnificent,--one of the finest sections of this formation exhibited anywhere in britain, perhaps in the world. in a ravine furrowed in the face of the declivity by the headlong descent of a small stream, we may trace all the beds of the system in succession, from the cornbrash, an upper deposit of the lower oölite, down to the lias, the formation on which the oölite rests. the only modifying circumstance to the geologist is, that though the sandstone beds run continuously along the cliff for miles together, distinct as the white bands in a piece of onyx, the intervening beds of shale are swarded over, save where we here and there see them laid bare in some abrupter acclivity or deeper water-course. in the shale we find numerous minute ammonites, sorely weathered; in the sandstone, belemnites, some of them of great size; and dark carbonaceous markings, passing not unfrequently into a glossy cubical coal. at the foot of the cliff i picked up an ammonite of considerable size and well-marked character,--the _ammonites murchisonæ_, first discovered on this coast by sir r. murchison about fifteen years ago. it measures, when full grown, from six to seven inches in diameter; the inner whorls, which are broadly visible, are ribbed; whereas the two, and sometimes the three outer ones, are smooth,--a marked characteristic of the species. my specimen merely enabled me to examine the peculiarities of the shell just a little more minutely than i could have done in the pages of sowerby; for such was its state of decay, that it fell to pieces in my hands. i had now come full in view of the rocky island of holm, when the altered appearance of the heavens led me to deliberate, just as i was warming in the work of exploration, whether, after all, it might not be well to scale the cliffs, and strike directly on the inn. it was nearly three o'clock; the sky had been gradually darkening since noon, as if one thin covering of gauze after another had been drawn over it; hill and island had first dimmed and then disappeared in the landscape; and now the sun stood up right over the fast-contracting vista of the sound, round and lightless as the moon in a haze; and the downward cataract-like streaming of the gray vapor on the horizon showed that there the rain had already broken, and was descending in torrents. we had been thirsty in the hot sun, and had found the springs few and scanty; but the boy now assured me, in very broken english, that we were to get a great deal more water than would be good for us, and that it might be advisable to get out of its way. and so, climbing to the top of the cliffs, along a water-course, we reached the ridge, just as the fog came rolling downwards from the peaked brow of the storr into the flat moory valley, and the melancholy lochans roughened and darkened in the rain. we were both particularly wet ere we reached portree. in exploring our scotch formations, i have had frequent occasion, in ross, sutherland, caithness, and now once more in skye, to pass over ground described by sir r. murchison; and in every instance have i found myself immensely his debtor. his descriptions possess the merit of being true: they are simple outlines often, that leave much to be filled up by after discovery; but, like those outlines of the skilful geographer that fix the place of some island or strait, though they may not entirely define it, they always indicate the exact position in the scale of the formations to which they refer. they leave a good deal to be done in the way of mapping out the interior of a deposit, if i may so speak; but they leave nothing to be done in the way of ascertaining its place. the work accomplished is _bona fide_ work,--actual, solid, not to be done over again,--work such as could be achieved in only the school of dr. william smith, the father of english geology. i have found much to admire, too, in the sections of sir r. murchison. his section of this part of the coast, for example, strikes from the extreme northern part of skye to the island of holm, thence to scrapidale in rasay, thence along part of the coast of scalpa, thence direct through the middle of pabba, and thence to the shore of the bay of laig. the line thus taken includes, in regular sequence in the descending order, the whole oölitic deposits of the hebrides, from the cornbrash, with its overlying fresh-water outliers of mayhap the weald, down to where the lower lias rests on the primary red sandstones of sleat. it would have cost m'culloch less exploration to have written a volume than it must have cost sir r. murchison to draw this single line; but the line once drawn, is work done to the hands of all after explorers. i have followed repeatedly in the track of another geologist, of, however, a very different school, who explored, at a comparatively recent period, the deposits of not a few of our scotch counties. but his labors, in at least the fossiliferous formations, seem to have accomplished nothing for geology,--i am afraid, even less than nothing. so far as they had influence at all, it must have been to throw back the science. a geologist who could have asserted only three years ago ("geognostical account of banffshire," ), that the old red sandstone of scotland forms merely "a part of the great coal deposit," could have known marvellously little of the fossils of the one system, and nothing whatever of those of the other. had he examined ere he decided, instead of deciding without any intention of examining, he would have found that, while both systems abound in organic remains, they do not possess, in scotland at least, a single species in common, and that even their types of being, viewed in the group, are essentially distinct. the three edinburgh gentlemen whom i had met at breakfast were still in the inn. one of them i had seen before, as one of the guests at a wesleyan soiree, though i saw he failed to remember that i had been there as a guest too. the two other gentlemen were altogether strangers to me. one of them,--a man on the right side of forty, and a superb specimen of the powerful, six-feet two-inch norman celt,--i set down as a scion of some old highland family, who, as the broadsword had gone out, carried on the internal wars of the country with the formidable artillery of statute and decision. the other, a gentleman more advanced in life, i predicated to be a highland proprietor, the uncle of the younger of the two,--a man whose name, as he had an air of business about him, occurred, in all probability, in the almanac, in the list of scotch advocates. both were of course high tories,--i was quite sure of that,--zealous in behalf of the establishment, though previous to the disruption they had not cared for it a pin's point,--and prepared to justify the virtual suppression of the toleration laws in the case of the free church. i was thus decidedly guilty of what old dr. more calls a _prosopolepsia_,--_i.e._ of the crime of judging men by their looks. at dinner, however, we gradually ate ourselves into conversation: we differed, and disputed, and agreed, and then differed, disputed and agreed again. i found first, that my chance companions were really not very high tories; and then, that they were not tories at all; and then, that the younger of the two was very much a whig, and the more advanced in life,--strange as the fact might seem,--very considerably a _presbyterian_ whig; and finally, that this latter gentleman, whom i had set down as an intolerant highland proprietor, was a respected writer to the signet, a free church elder in edinburgh; and that the other, his equally intolerant nephew, was an edinburgh advocate, of vigorous talent, much an enemy of all oppression, and a brother contributor of my own to one of the quarterlies. of all my surmisings regarding the stranger gentlemen, only two points held true,--they were both gentlemen of the law, and both had celtic blood in their veins. the evening passed pleasantly; and i can now recommend from experience, to the hapless traveller who gets thoroughly wet thirty miles from a change of dress, that some of the best things he can resort to in the circumstances are, a warm room, a warm glass, and agreeable companions. on the morrow i behooved to return to isle ornsay, to set out on the following day, with my friend the minister, for rum, where he purposed preaching on the sabbath. to have lost a day would have been to lose the opportunity of exploring the island, perhaps forever; and, to make all sure, i had taken a seat in the mail gig, from the postman who drives it, ere going to bed, on the morning of my arrival; and now, when it drove up, i went to take my place in it. the postmaster of the village, a lean, hungry-looking man, interfered to prevent me. i had secured my seat, i said, two days previous. ah, but i had not secured it from him. "i know nothing of you," i replied; "but i secured it from one who deemed himself authorized to receive the fare; was he so?" "yes." "could you have received it?" "no." "show me a copy of your regulations." "i have no copy of regulations; but i have given the place in the gig to another." "just so; and what say you, postman?" "that you took the place from me, and that _he_ has no right to give a place to any one: i carry the portree letters to him, but he has nothing to do with the passengers." a person present, the proprietor or stabler of the horse, i believe, also interfered on the same side; but what carlyle terms the "gigmanity" of the postmaster was all at stake,--his whole influence in the mail-gig of portree; and so he argued, and threatened withal, and, what was the more serious part of the business, the person he had given the seat to had taken possession of the gig; and so we had to compound the matter by carrying a passenger additional. the incident is scarce worth relating; but the postmaster was so vehement and terrible, so defiant of us all,--post, stabler, and simple passenger,--and so justly impressed with the importance of being postmaster of portree, that, as i am in the way of describing rare specimens at any rate, i must refer to him among the rest, as if he had been one of the minor carnivoræ of a skye deposit,--a cuttlefish, that preyed on the weaker molluscs, or a hungry polypus, terrible among the animalculæ. we drove heavily, and had to dismount and walk afoot over every steeper acclivity; but i carried my hammer, and only grieved that in some one or two localities the road should have been so level. i regretted it in especial on the southern and eastern side of loch sligachan, where i could see from my seat, as we drove past, the dark blue rocks in the water-courses on each side the road, studded over with that characteristic shell of the lias, the _gryphæa incurva_, and that the dry-stone fences in the moor above exhibit fossils that might figure in a museum. but we rattled by. at broadford, twenty-five miles from portree, and nine miles from isle ornsay, i partook of a hospitable meal in the house of an acquaintance; and in little more than two hours after was with my friend the minister at isle ornsay. the night wore pleasantly by. mrs. swanson, a niece of the late dr. smith of campbelton, so well known for his celtic researches and his exquisite translations of ancient celtic poetry, i found deeply versed in the legendary lore of the highlands. the minister showed me a fine specimen of pterichthys which i had disinterred for him, out of my first discovered fossiliferous deposit of the old red sandstone, exactly thirteen years before, and full seven years ere i had introduced the creature to the notice of agassiz. and the minister's daughter, a little chubby girl of three summers, taking part in the general entertainment, strove to make her gaelic sound as like english as she could, in my especial behalf. i remembered, as i listened to the unintelligible prattle of the little thing, unprovided with a word of english, that just eighteen years before, her father had had no gaelic; and wondered what he would have thought, could he have been told, when he first sat down to study it, the story of his island charge in eigg, and his free church yacht the betsey. nineteen years before, we had been engaged in beating over the eathie lias together, collecting belemnites, ammonites, and fossil wood, and striving in friendly emulation the one to surpass the other in the variety and excellence of our specimens. our leisure hours were snatched, at the time, from college studies by the one, from the mallet by the other: there were few of them that we did not spend together, and that we were not mutually the better for so spending. i at least, owe much to these hours,--among other things, views of theologic truth, that determined the side i have taken in our ecclesiastical controversy. our courses at an after period lay diverse; the young minister had greatly more important business to pursue than any which the geologic field furnishes; and so our amicable rivalry ceased early. in the words in which an english poet addresses his brother,--the clergyman who sat for the picture in the "deserted village,"--my friend "entered on a sacred office, where the harvest is great and the laborers are few, and left to me a field in which the laborers are many, and the harvest scarce worth carrying away." next day at noon we weighed anchor, and stood out for rum, a run of about twenty-five miles. a kind friend had, we found, sent aboard in our behalf two pieces of rare antiquity,--rare anywhere, but especially rare in the lockers of the betsey,--in the agreeable form of two bottles of semi-fossil madeira,--madeira that had actually existed in the grape exactly half a century before, at the time when robespierre was startling paris from its propriety, by mutilating at the neck the busts of other people, and multiplying casts and medals of his own; and we found it, explored in moderation, no bad study for geologists, especially in coarse weather, when they had got wet and somewhat fatigued. it was like landlord boniface's ale, mild as milk, had exchanged its distinctive flavor as madeira for a better one, and filled the cabin with fragrance every time the cork was drawn. old observant homer must have smelt some such liquor somewhere, or he could never have described so well the still more ancient and venerable wine with which wily ulysses beguiled one-eyed polypheme:-- "unmingled wine, mellifluous, undecaying, and divine, which now, some ages from his race concealed, the hoary sire in gratitude revealed.... scarce twenty measures from the living stream to cool one cup sufficed: the goblet crowned, breathed aromatic fragrances around." winds were light and variable. as we reached the middle of the sound opposite armadale, there fell a dead calm; and the betsey, more actively idle than the ship manned by the ancient mariner, dropped sternwards along the tide, to the dull music of the flapping sail. the minister spent the day in the cabin, engaged with his discourse for the morrow; and i, that he might suffer as little from interruption as possible, _mis_-spent it upon the deck. i tried fishing with the yacht's set of lines, but there were no fish to bite,--got into the boat, but there were no neighboring islands to visit,--and sent half a dozen pistol-bullets after a shoal of porpoises, which, coming from the free church yacht, must have astonished the fat sleek fellows pretty considerably, but did them, i am afraid, no serious damage. as the evening began to close gloomy and gray, a tumbling swell came heaving in right ahead from the west; and a bank of cloud, which had been gradually rising higher and darker over the horizon in the same direction, first changed its abrupt edge atop for a diffused and broken line, and then spread itself over the central heavens. the calm was evidently not to be a calm long; and the minister issued orders that the gaff-topsail should be taken down, and the storm-jib bent; and that we should lower our topmast, and have all tight and ready for a smart gale ahead. at half past ten, however, the betsey was still pitching to the swell, with not a breath of wind to act on the diminished canvas, and with the solitary circumstance in her favor, that the tide ran no longer against her, as before. the cabin was full of all manner of creakings; the close lamp swung to and fro over the head of my friend; and a refractory concordance, after having twice travelled from him along the entire length of the table, flung itself pettishly upon the floor. i got into my snug bed about eleven; and at twelve, the minister, after poring sufficiently over his notes, and drawing the final score, turned into his. in a brief hour after, on came the gale, in a style worthy of its previous hours of preparation; and my friend,--his saturday's work in his ministerial capacity well over when he had completed his two discourses,--had to begin the sabbath morning early as the morning itself began, by taking his stand at the helm, in his capacity of skipper of the betsey. with the prospect of the services of the sabbath before him, and after working all saturday to boot, it was rather hard to set him down to a midnight spell at the helm, but he could not be wanted at such a time, as we had no other such helmsman aboard. the gale, thickened with rain, came down, shrieking like a maniac, from off the peaked hills of rum, striking away the tops of the long ridgy billows that had risen in the calm to indicate its approach, and then carrying them in sheets of spray aslant the furrowed surface, like snow-drift hurried across a frozen field. but the betsey, with her storm-jib set, and her mainsail reefed to the cross, kept her weather bow bravely to the blast, and gained on it with every tack. she had been the pleasure yacht, in her day, of a man of fortune, who had used, in running south with her at times as far as lisbon, to encounter, on not worse terms than the stateliest of her neighbors in the voyage, the swell of the bay of biscay; and she still kept true to her old character, with but this drawback, that she had now got somewhat crazy in her fastenings, and made rather more water in a heavy sea than her one little pump could conveniently keep under. as the fitful gust struck her headlong, as if it had been some invisible missile hurled at us from off the hill-tops, she stooped her head lower and lower, like old stately hardyknute under the blow of the "king of norse," till at length the lee chain-plate rustled sharp through the foam; but, like a staunch free churchwoman, the lowlier she bent, the more steadfastly did she hold her head to the storm. the strength of the opposition served but to speed her on all the more surely to the desired haven. at five o'clock in the morning we cast anchor in loch scresort,--the only harbor of rum in which a vessel can moor,--within two hundred yards of the shore, having, with the exception of the minister, gained no loss in the gale. he, luckless man, had parted from his excellent _sou-wester_; a sudden gust had seized it by the flap, and hurried it away far to the lee. he had yielded it to the winds, as he had done the temporalities, but much more unwillingly, and less as a free agent. should any conscientious mariner pick up any where in the atlantic a serviceable ochre-colored _sou-wester_, not at all the worse for the wear, i give him to wit that he holds free church property, and that he is heartily welcome to hold it, leaving it to himself to consider whether a benefaction to its full value, deducting salvage, is not owing, in honor, to the sustenation fund. it was ten o'clock ere the more fatigued aboard could muster resolution enough to quit their beds a second time; and then it behooved the minister to prepare for his sabbath labors ashore. the gale still blew in fierce gusts from the hills, and the rain pattered like small shot on the deck. loch scresort, by no means one of our finer island lochs, viewed under any circumstances, looked particularly dismal this morning. it forms the opening of a dreary moorland valley, bounded on one of its sides, to the mouth of the loch, by a homely ridge of old red sandstone, and on the other by a line of dark augitic hills, that attain, at the distance of about a mile from the sea, an elevation of two thousand feet. along the slopes of the sandstone ridge i could discern, through the haze, numerous green patches, that had once supported a dense population, long since "cleared off" to the backwoods of america, but not one inhabited dwelling; while along a black moory acclivity under the hills on the other side i could see several groups of turf cottages, with here and there a minute speck of raw-looking corn beside them, that, judging from its color, seemed to have but a slight chance of ripening. the hill-tops were lost in cloud and storm; and ever and anon, as a heavier shower came sweeping down on the wind, the intervening hollows closed up their gloomy vistas, and all was fog and rime to the water's edge. bad as the morning was, however, we could see the people wending their way, in threes and fours, through the dark moor, to the place of worship,--a black turf hovel, like the meeting-house in eigg. the appearance of the betsey in the loch had been the gathering signal; and the free church islanders,--three-fourths of the entire population--had all come out to meet their minister. on going ashore, we found the place nearly filled. my friend preached two long energetic discourses, and then returned to the yacht, "a worn and weary man." the studies of the previous day, and the fatigues of the previous night, added to his pulpit duties, had so fairly prostrated his strength, that the sternest teetotaller in the kingdom would scarce have forbidden him a glass of our fifty-year-old madeira. but even the fifty-year-old madeira proved no specific in the case. he was suffering under excruciating headache, and had to stretch himself in his bed, with eyes shut but sleepless, waiting till the fit should pass,--every pulse that beat in his temples a throb of pain. chapter viii. geology of rum--its curious character illustrated--rum famous for bloodstones--red sandstones--"scratchings" in the rocks--a geological inscription without a key--the lizard--vitality broken into two--illustrations--speculation--scuir more--ascent of the scuir--the bloodstones--an illustrative set of the gem--m'culloch's pebble--a chemical problem--the solitary shepherd's house--sheep _versus_ men--the depopulation of rum--a haul of trout--rum mode of catching trout--at anchor in the bay of glenelg. the geology of the island of rum is simple, but curious. let the reader take, if he can, from twelve to fifteen trap-hills, varying from one thousand to two thousand three hundred feet in height; let him pack them closely and squarely together, like rum-bottles in a case-basket; let him surround them with a frame of old red sandstone, measuring rather more than seven miles on the side, in the way the basket surrounds the bottles; then let him set them down in the sea a dozen miles off the land,--and he shall have produced a second island of rum, similar in structure to the existing one. in the actual island, however, there is a defect in the inclosing basket of sandstone: the basket, complete on three of its sides, wants the fourth: and the side opposite to the gap which the fourth should have occupied is thicker than the two other sides put together. where i now write there is an old dark-colored picture on the wall before me. i take off one of the four bars of which the frame is composed,--the end-bar,--and stick it on to the end-bar opposite, and then the picture is fully framed on two of its sides, and doubly framed on a third, but the fourth side lacks framing altogether. and such is the geology of the island of rum. we find the one loch of the island,--that in which the betsey lies at anchor,--and the long withdrawing valley, of which the loch is merely a prolongation, occurring in the double sandstone bar: it seems to mark--to return to my illustration--the line in which the superadded piece of frame has been stuck on to the frame proper. the origin of the island is illustrated by its structure: it has left its story legibly written, and we have but to run our eye over the characters and read. an extended sea-bottom, composed of old red sandstone, already tilted up by previous convulsions, so that the strata presented their edges, tier beyond tier, like roofing slate laid aslant on a floor, became a centre of plutonic activity. the molten trap broke through at various times, and presenting various appearances, but in nearly the same centre; here existing as an augitic rock, there as a syenite, yonder as a basalt or amygdaloid. at one place it uptilted the sandstone; at another it overflowed it; the dark central masses raised their heads above the surface, higher and higher with every earthquake throe from beneath; till at length the gigantic ben more attained to its present altitude of two thousand three hundred feet over the sea-level, and the sandstone, borne up from beneath like floating sea-wrack on the back of a porpoise, reached in long outside bands its elevation of from six to eight hundred. and such is the piece of history, composed in silent but expressive language, and inscribed in the old geological character, on the rocks of rum. the wind lowered and the rain ceased during the night, and the morning of monday was clear, bracing, and breezy. the island of rum is chiefly famous among mineralogists for its heliotropes or bloodstones; and we proposed devoting the greater part of the day to an examination of the hill of scuir more, in which they occur, and which lies on the opposite side of the island, about eight miles from the mooring ground of the betsey. ere setting out, however, i found time enough, by rising some two or three hours before breakfast, to explore the red sandstones on the southern side of the loch. they lie in this bar of the frame,--to return once more to my old illustration,--as if it had been cut out of a piece of cross-grained deal, in which the annular bands, instead of ranging lengthwise, ran diagonally from side to side; stratum leans over stratum, dipping towards the west at an angle of about thirty degrees; and as in a continuous line of more than seven miles there seem no breaks or repetitions in the strata, the thickness of the deposit must be enormous,--not less, i should suppose, than from six to eight thousand feet. like the lower old red sandstones of cromarty and moray, the red arenaceous strata occur in thick beds, separated from each other by bands of a grayish-colored stratified clay, on the planes of which i could trace with great distinctness ripple markings; but in vain did i explore their numerous folds for the plates, scales, and fucoid impressions which abound in the gray argillaceous beds of the shores of the moray and cromarty friths. it would, however, be rash to pronounce them non-fossiliferous, after the hasty search of a single morning,--unpardonably so in one who had spent very many mornings in putting to the question the gray stratified beds of ross and cromarty, ere he succeeded in extorting from them the secret of their organic riches. we set out about half-past ten for scuir more, through the red sandstone valley in which loch scresort terminates, with one of mr. swanson's people, a young active lad of twenty, for our guide. in passing upwards for nearly a mile along the stream that falls into the upper part of the loch, and lays bare the strata, we saw no change in the character of the sandstone. red arenaceous beds of great thickness alternate with grayish-colored bands, composed of a ripple-marked micaceous slate and a stratified clay. for a depth of full three thousand feet, and i know not how much more,--for i lacked time to trace it further,--the deposit presents no other variety: the thick red bed of at least a hundred yards succeeds the thin gray band of from three to six feet, and is succeeded by a similar gray band in turn. the ripple-marks i found as sharply relieved in some of the folds as if the wavy undulations to which they owed their origin had passed over them within the hour. the comparatively small size of their alternating ridges and furrows give evidence that the waters beneath which they had formed had been of no very profound depth. in the upper part of the valley, which is bare, trackless, and solitary, with a high monotonous sandstone ridge bounding it on the one side, and a line of gloomy trap-hills rising over it on the other, the edges of the strata, where they protrude through the mingled heath and moss, exhibit the mysterious scratchings and polishings now so generally connected with the glacial theory of agassiz. the scratchings run in nearly the line of the valley, which exhibits no trace of moraines; and they seem to have been produced rather by the operation of those extensively developed causes, whatever their nature, that have at once left their mark on the sides and summits of some of our highest hills, and the rocks and boulders of some of our most extended plains, than by the agency of forces limited to the locality. they testify, agassiz would perhaps say, not regarding the existence of some local glacier that descended from the higher grounds into the valley, but respecting the existence of the great polar glacier. i felt, however, in this bleak and solitary hollow, with the grooved and polished platforms at my feet, stretching away amid the heath, like flat tombstones in a graveyard, that i had arrived at one geologic inscription to which i still wanted the key. the vesicular structure of the traps on the one hand, identical with that of so many of our modern lavas,--the ripple-markings of the arenaceous beds on the other, indistinguishable from those of the sea-banks on our coasts,--the upturned strata and the overlying trap,--told all their several stories of fire, or wave, or terrible convulsion, and told them simply and clearly; but here was a story not clearly told. it summoned up doubtful, ever-shifting visions,--now of a vast ice continent, abutting on this far isle of the hebrides from the pole, and trampling heavily over it,--now of the wild rush of a turbid, mountain-high flood breaking in from the west, and hurling athwart the torn surface, rocks, and stones, and clay,--now of a dreary ocean rising high along the hills, and bearing onward with its winds and currents, huge icebergs, that now brushed the mountain-sides, and now grated along the bottom of the submerged valleys. the inscription on the polished surfaces, with its careless mixture of groove and scratch, is an inscription of very various readings. we passed along a transverse hollow, and then began to ascend a hill-side, from the ridge of which the water sheds to the opposite shore of the island, and on which we catch our first glimpse of scuir more, standing up over the sea, like a pyramid shorn of its top. a brown lizard, nearly five inches in length, startled by our approach, ran hurriedly across the path; and our guide, possessed by the general highland belief that the creature is poisonous, and injures cattle, struck at it with a switch, and cut it in two immediately behind the hinder legs. the upper half, containing all that anatomists regard as the vitals, heart, brain, and viscera, all the main nerves, and all the larger arteries, lay stunned by the blow, as if dead; nor did it manifest any signs of vitality so long as we remained beside it; whereas the lower half, as if the whole life of the animal had retired into _it_, continued dancing upon the moss for a full minute after, like a young eel scooped out of some stream, and thrown upon the bank; and then lay wriggling and palpitating for about half a minute more. there are few things more inexplicable in the province of the naturalist than the phenomenon of what may be termed divided life,--vitality broken into two, and yet continuing to exist as vitality in both the dissevered pieces. we see in the nobler animals mere glimpses of the phenomenon,--mere indications of it, doubtfully apparent for at most a few minutes. the blood drawn from the human arm by the lancet continues to live in the cup until it has cooled and begun to coagulate; and when head and body have parted company under the guillotine, both exhibit for a brief space such unequivocal signs of life, that the question arose in france during the horrors of the revolution, whether there might not be some glimmering of consciousness attendant at the same time on the fearfully opening and shutting eyes and mouth of the one, and the beating heart and jerking neck of the other. the lower we descend in the scale of being, the more striking the instances which we receive of this divisibility of the vital principle. i have seen the two halves of the heart of a ray pulsating for a full quarter of an hour after they had been separated from the body and from each other. the blood circulates in the hind leg of a frog for many minutes after the removal of the heart, which meanwhile keeps up an independent motion of its own. vitality can be so divided in the earthworm, that, as demonstrated by the experiments of spalanzani, each of the severed parts carries life enough away to set it up as an independent animal; while the polypus, a creature of still more imperfect organization, and with the vivacious principle more equally diffused over it, may be multiplied by its pieces nearly as readily as a gooseberry bush by its slips. it was sufficiently curious, however, to see, in the case of this brown lizard, the least vital half of the creature so much more vivacious, apparently, than the half which contained the heart and brain. it is not improbable, however, that the presence of these organs had only the effect of rendering the upper portion which contained them more capable of being thrown into a state of insensibility. a blow dealt one of the vertebrata on the head at once renders it insensible. it is after this mode the fisherman kills the salmon captured in his wear, and a single blow, when well directed, is always sufficient; but no single blow has the same effect on the earthworm; and here it was vitality in the inferior portion of the reptile,--the earthworm portion of it, if i may so speak,--that refused to participate in the state of syncope into which the vitality of the superior portion had been thrown. the nice and delicate vitality of the brain seems to impart to the whole system in connection with it an aptitude for dying suddenly,--a susceptibility of instant death, which would be wanting without it. the heart of the rabbit continues to beat regularly long after the brain has been removed by careful excision, if respiration be artificially kept up; but if, instead of amputating the head, the brain be crushed in its place by a sudden blow of a hammer, the heart ceases its motion at once. and such seemed to be the principle illustrated here. but why the agonized dancing on the sward of the inferior part of the reptile?--why its after painful writhing and wriggling? the young eel scooped from the stream, whose motions it resembled, is impressed by terror, and can feel pain; was _it_ also impressed by terror, or susceptible of suffering? we see in the case of both exactly the same signs,--the dancing, the writhing, the wriggling; but are we to interpret them after the same manner? in the small red-headed earthworm divided by spalanzani, that in three months got upper extremities to its lower part, and lower extremities, in as many weeks, to its upper part, the dividing blow must have dealt duplicate feelings,--pain and terror to the portion below, and pain and terror to the portion above,--so far, at least, as a creature so low in the scale was susceptible of these feelings; but are we to hold that the leaping, wriggling tail of the reptile possessed in any degree a similar susceptibility? _i_ can propound the riddle, but who shall resolve it? it may be added, that this brown lizard was the only recent saurian i chanced to see in the hebrides, and that, though large for its kind, its whole bulk did not nearly equal that of a single vertebral joint of the fossil saurians of eigg. the reptile, since his deposition from the first place in the scale of creation, has sunk sadly in those parts: the ex-monarch has become a low plebeian. we came down upon the coast through a swampy valley, terminating in the interior in a frowning wall of basalt, and bounded on the south, where it opens to the sea, by the scuir more. the scuir is a precipitous mountain, that rises from twelve to fifteen hundred feet direct over the beach. m'culloch describes it as inaccessible, and states that it is only among the debris at its base that its heliotropes can be procured; but the distinguished mineralogist must have had considerably less skill in climbing rocks than in describing them, as, indeed, some of his descriptions, though generally very admirable, abundantly testify. i am inclined to infer from his book, after having passed over much of the ground which he describes, that he must have been a man of the type so well hit off by burns in his portrait of captain grose,--round, rosy, short-legged, quick of eye but slow of foot, quite as indifferent a climber as bailie nicol jarvie, and disposed at times, like the elderly gentleman drawn by crabbe, to prefer the view at the hill-foot to the prospect from its summit. i found little difficulty in scaling the sides of scuir more for a thousand feet upwards,--in one part by a route rarely attempted before,--and in ensconcing myself among the bloodstones. they occur in the amygdaloidal trap of which the upper part of the hill is mainly composed, in great numbers, and occasionally in bulky masses; but it is rare to find other than small specimens that would be recognized as of value by the lapidary. the inclosing rock must have been as thickly vesicular in its original state as the scoria of a glass-house; and all the vesicles, large and small, like the retorts and receivers of a laboratory, have been vessels in which some curious chemical process has been carried on. many of them we find filled with a white semi-translucent or opaque chalcedony; many more with a pure green earth, which, where exposed to the bleaching influences of the weather, exhibits a fine verdigris hue, but which in the fresh fracture is generally of an olive green, or of a brownish or reddish color. i have never yet seen a rock in which this earth was so abundant as in the amygdaloid of scuir more. for yards together in some places we see it projecting from the surface in round globules, that very much resemble green peas, and that occur as thickly in the inclosing mass as pebbles in an old red sandstone conglomerate. the heliotrope has formed among it in centres, to which the chalcedony seems to have been drawn, as if by molecular attraction. we find a mass, varying from the size of a walnut to that of a man's head, occupying some larger vesicle or crevice of the amygdaloid, and all the smaller vesicles around it, for an inch or two, filled with what we may venture to term satellite heliotropes, some of them as minute as grains of wild mustard, and all of them more or less earthy, generally in proportion to their distance from the first formed heliotrope in the middle. no one can see them in their place in the rock, with the abundant green earth all around, and the chalcedony, in its uncolored state, filling up so many of the larger cavities, without acquiescing in the conclusion respecting the origin of the gem first suggested by werner, and afterwards adopted and illustrated by m'culloch. the heliotrope is merely a chalcedony, stained in the forming with an infusion of green earth, as the colored waters in the apothecary's window are stained by the infusions, vegetable and mineral, from which they derive their ornamental character. the red mottlings which so heighten the beauty of the stone occur in comparatively few of the specimens of scuir more. they are minute jasperous formations, independent of the inclosing mass; and, from their resemblance to streaks and spots of blood, suggest the name by which the heliotrope is popularly known. i succeeded in making up, among the crags, a set of specimens curiously illustrative of the origin of the gem. one specimen consists of white, uncolored chalcedony; a second, of a rich verdigris-hued green earth; a third, of chalcedony barely tinged with green; a fourth, of chalcedony tinged just a shade more deeply; a fifth, tinged more deeply still; a sixth, of a deep green on one side, and scarce at all colored on the other; and a seventh, dark and richly toned,--a true bloodstone,--thickly streaked and mottled with red jasper. in the chemical process that rendered the scuir more a mountain of gems there were two deteriorating circumstances, which operated to the disadvantage of its larger heliotropes: the green earth, as if insufficiently stirred in the mixing, has gathered, in many of them, into minute soft globules, like air-bubbles in glass, that render them valueless for the purposes of the lapidary, by filling them all over with little cavities; and in not a few of the others, an infiltration of lime, that refused to incorporate with the chalcedonic mass, exists in thin glassy films and veins, that, from their comparative softness, have a nearly similar effect with the impalpable green earth in roughing the surface under the burnisher. we find figured by m'culloch, in his "western islands," the internal cavity of a pebble of scuir more, which he picked up on the beach below, and which had been formed evidently within one of the larger vesicles of the amygdaloid. he describes it as curiously illustrative of a various chemistry; the outer crust is composed of a pale-zoned agate, inclosing a cavity, from the upper side of which there depends a group of chalcedonic stalactites, some of them, as in ancient spar caves, reaching to the floor; and bearing on its under side a large crystal of carbonate of lime, that the longer stalactites pass through. in the vesicle in which this hollow pebble was formed three consecutive processes must have gone on. first, a process of infiltration coated the interior all around with layer after layer, now of one mineral substance, now of another, as a plasterer coats over the sides and ceiling of a room with successive layers of lime, putty, and stucco; and had this process gone on, the whole cell would have been filled with a pale-zoned agate. but it ceased, and a new process began. a chalcedonic infiltration gradually entered from above; and, instead of coating over the walls, roof, and floor, it hardened into a group of spear-like stalactites, that lengthened by slow degrees, till some of them had traversed the entire cavity from top to bottom. and then this second process ceased like the first, and a third commenced. an infiltration of lime took place; and the minute calcareous molecules, under the influence of the law of crystallization, built themselves up on the floor into a large smooth-sided rhomb, resembling a closed sarcophagus resting in the middle of some egyptian cemetery. and then, the limestone crystal completed, there ensued no after change. as shown by some other specimens, however, there was a yet farther process: a pure quartzose deposition took place, that coated not a few of the calcareous rhombs with sprigs of rock-crystal. i found in the scuir more several cellular agates in which similar processes had gone on,--none of them quite so fine, however, as the one figured by m'culloch; but there seemed no lack of evidence regarding the strange and multifarious chemistry that had been carried on in the vesicular cavities of this mountain, as in the retorts of some vast laboratory. here was a vesicle filled with green earth,--there a vesicle filled with calcareous spar,--yonder a vesicle crusted round on a thin chalcedonic shell with rock-crystal,--in one cavity an agate had been elaborated, in another a heliotrope, in a third a milk-white chalcedony, in a fourth a jasper. on what principle, and under what direction, have results so various taken place in vesicles of the same rock, that in many instances occur scarce half an inch apart? why, for instance, should that vesicle have elaborated only green earth, and the vesicle separated from it by a partition barely a line in thickness, have elaborated only chalcedony? why should this chamber contain only a quartzose compound of oxygen and silica, and that second chamber beside it contain only a calcareous compound of lime and carbonic acid? what law directed infiltrations so diverse to seek out for themselves vesicles in such close neighborhood, and to keep, in so many instances, each to his own vesicle? i can but state the problem,--not solve it. the groups of heliotropes clustered each around its bulky centrical mass seem to show that the principle of molecular attraction may be operative in very dense mediæ,--in a hard amygdaloidal trap even; and it seems not improbable, that to this law, which draws atom to its kindred atom, as clansmen of old used to speed at the mustering signal to their gathering place, the various chemistry of the vesicles may owe its variety. i shall attempt stating the chemical problem furnished by the vesicles here in a mechanical form. let us suppose that every vesicle was a chamber furnished with a door, and that beside every door there watched, as in the draught doors of our coal-pits, some one to open and shut it, as circumstances might require. let us suppose further, that for a certain time an infusion of green earth pervaded the surrounding mass, and percolated through it, and that every door was opened to receive a portion of the infusion. we find that no vesicle wants its coating of this earthy mineral. the coating received, however, one-half the doors shut, while the other half remained agap, and filled with green earth entirely. next followed a series of alternate infusions of chalcedony, jasper, and quartz; many doors opened and received some two or three coatings, that form around the vesicles skull-like shells of agate, and then shut; a few remained open, and became as entirely occupied with agate as many of the previous ones had become filled with green earth. then an ample infusion of chalcedony pervaded the mass. numerous doors again opened; some took in a portion of the chalcedony, and then shut; some remained open, and became filled with it; and many more that had been previously filled by the green earth opened their doors again, and the chalcedony pervading the green porous mass, converted it into heliotrope. then an infusion of lime took place. doors opened, many of which had been hitherto shut, save for a short time, when the green earth infusion obtained, and became filled with lime; other doors opened for a brief space, and received lime enough to form a few crystals. last of all, there was a pure quartzose infusion, and doors opened, some for a longer time, some for a shorter, just as on previous occasions. now, by mechanical means of this character,--by such an arrangement of successive infusions, and such a device of shutting and opening of doors,--the phenomena exhibited by the vesicles could be produced. there is no difficulty in working the problem mechanically, if we be allowed to assume in our data successive infusions, well-fitted doors, and watchful door-keepers; and if any one can work it chemically,--certainly without door-keepers, but with such doors and such infusions as he can show to have existed,--he shall have cleared up the mystery of the scuir more. i have given their various cargoes to all its many vesicles by mechanical means, at no expense of ingenuity whatever. are there any of my readers prepared to give it to them by means purely chemical? there is a solitary house in the opening of the valley, over which the scuir more stands sentinel,--a house so solitary, that the entire breadth of the island intervenes between it and the nearest human dwelling. it is inhabited by a shepherd and his wife,--the sole representatives in the valley of a numerous population, long since expatriated to make way for a few flocks of sheep, but whose ranges of little fields may still be seen green amid the heath on both sides, for nearly a mile upwards from the opening. after descending along the precipices of the scuir, we struck across the valley, and, on scaling the opposite slope sat down on the summit to rest us, about a hundred yards over the house of the shepherd. he had seen us from below, when engaged among the bloodstones, and had seen, withal, that we were not coming his way; and, "on hospitable thoughts intent," he climbed to where we sat, accompanied by his wife, she bearing a vast bowl of milk, and he a basket of bread and cheese. and we found the refreshment most seasonable, after our long hours of toil, and with a rough journey still before us. it is an excellent circumstance, that hospitality grows best where it is most needed. in the thick of men it dwindles and disappears, like fruits in the thick of a wood; but where man is planted sparsely, it blossoms and matures, like apples on a standard or espalier. it flourishes where the inn and the lodging-house cannot exist, and dies out where they thrive and multiply. we reached the cross valley in the interior of the island about half an hour before sunset. the evening was clear, calm, golden-tinted; even wild heaths and rude rocks had assumed a flush of transient beauty; and the emerald-green patches on the hill-sides, barred by the plough lengthwise, diagonally, and transverse, had borrowed an aspect of soft and velvety richness, from the mellowed light and the broadening shadows. all was solitary. we could see among the deserted fields the grass-grown foundations of cottages razed to the ground; but the valley, more desolate than that which we had left, had not even its single inhabited dwelling: it seemed as if man had done with it forever. the island, eighteen years before, had been divested of its inhabitants, amounting at the time to rather more than four hundred souls, to make way for one sheep-farmer and eight thousand sheep. all the aborigines of rum crossed the atlantic; and at the close of , the entire population consisted of but the sheep-farmer, and a few shepherds, his servants; the island of rum reckoned up scarce a single family at this period for every five square miles of area which it contained. but depopulation on so extreme a scale was found inconvenient; the place had been rendered too thoroughly a desert for the comfort of the occupant; and on the occasion of a clearing which took place shortly after in skye, he accommodated some ten or twelve of the ejected families with sites for cottages, and pasturage for a few cows, on the bit of morass beside loch scresort, on which i had seen their humble dwellings. but the whole of the once-peopled interior remains a wilderness, without inhabitant,--all the more lonely in its aspect from the circumstance that the solitary valleys, with their plough-furrowed patches, and their ruined heaps of stone, open upon shores every whit as solitary as themselves, and that the wide untrodden sea stretches drearily around. the armies of the insect world were sporting in the light this evening by millions; a brown stream that runs through the valley yielded an incessant popling sound, from the myriads of fish that were ceaselessly leaping in the pools, beguiled by the quick glancing wings of green and gold that fluttered over them; along a distant hill-side there ran what seemed the ruins of a gray-stone fence, erected, says tradition, in a remote age, to facilitate the hunting of the deer; there were fields on which the heath and moss of the surrounding moorlands were fast encroaching, that had borne many a successive harvest; and prostrate cottages, that had been the scenes of christenings, and bridals, and blythe new-year's days;--all seemed to bespeak the place a fitting habitation for man, in which not only the necessaries, but also a few of the luxuries of life, might be procured; but in the entire prospect not a man nor a man's dwelling could the eye command. the landscape was one without figures. i do not much like extermination carried out so thoroughly and on system;--it seems bad policy; and i have not succeeded in thinking any the better of it though assured by economists that there are more than people enough in scotland still. there are, i believe, more than enough in our workhouses,--more than enough on our pauper-rolls,--more than enough huddled up, disreputable, useless, and unhappy, in the miasmatic alleys and typhoid courts of our large towns; but i have yet to learn how arguments for local depopulation are to be drawn from facts such as these. a brave and hardy people, favorably placed for the development of all that is excellent in human nature, form the glory and strength of a country;--a people sunk into an abyss of degradation and misery, and in which it is the whole tendency of external circumstances to sink them yet deeper, constitute its weakness and its shame; and i cannot quite see on what principle the ominous increase which is taking place among us in the worse class, is to form our solace or apology for the wholesale expatriation of the better. it did not seem as if the depopulation of rum had tended much to any one's advantage. the single sheep-farmer who had occupied the holdings of so many had been unfortunate in his speculations, and had left the island: the proprietor, his landlord, seemed to have been as little fortunate as the tenant, for the island itself was in the market; and a report went current at the time, that it was on the eve of being purchased by some wealthy englishman, who purposed converting it into a deer-forest. how strange a cycle! uninhabited originally save by wild animals, it became at an early period a home of men, who, as the gray wall on the hill-side testified, derived, in part at least, their sustenance from the chase. they broke in from the waste the furrowed patches on the slopes of the valleys,--they reared herds of cattle and flocks of sheep,--their number increased to nearly five hundred souls,--they enjoyed the average happiness of human creatures in the present imperfect state of being,--they contributed their portion of hardy and vigorous manhood to the armies of the country,--and a few of their more adventurous spirits, impatient of the narrow bounds which confined them, and a course of life little varied by incident, emigrated to america. then came the change of system so general in the highlands; and the island lost all its original inhabitants, on a wool and mutton speculation,--inhabitants, the descendants of men who had chased the deer on its hills five hundred years before, and who, though they recognized some wild island lord as their superior, and did him service, had regarded the place as indisputably their own. and now yet another change was on the eve of ensuing, and the island was to return to its original state, as a home of wild animals, where a few hunters from the mainland might enjoy the chase for a month or two every twelvemonth, but which could form no permanent place of human abode. once more, a strange and surely most melancholy cycle! there was light enough left, as we reached the upper part of loch scresort, to show us a shoal of small silver-coated trout, leaping by scores at the effluence of the little stream along which we had set out in the morning on our expedition. there was a net stretched across where the play was thickest; and we learned that the haul of the previous tide had amounted to several hundreds. on reaching the betsey, we found a pail and basket laid against the companion-head,--the basket containing about two dozen small trout,--the minister's unsolicited teind of the morning draught; the pail filled with razor-fish of great size. the people of my friend are far from wealthy; there is scarce any circulating medium in rum; and the cottars in eigg contrive barely enough to earn at the harvest in the lowlands money sufficient to clear with their landlord at rent-day. their contributions for ecclesiastical purposes make no great figure, therefore, in the lists of the sustentation fund. but of what they have they give willingly and in a kindly spirit; and if baskets of small trout, or pailfuls of spout-fish, went current in the free church, there would, i am certain, be a per centage of both the fish and the mollusc, derived from the small isles, in the half-yearly sustentation dividends. we found the supply of both,--especially as provisions were beginning to run short in the lockers of the betsey,--quite deserving of our gratitude. the razor-fish had been brought us by the worthy catechist of the island. he had gone to the ebb in our special behalf, and had spent a tide in laboriously filling the pail with these "treasures hid in the sand;" thoroughly aware, like the old exiled puritan, who eked out his meals in a time of scarcity with the oysters of new england, that even the razor-fish, under this head, is included in the promises. there is a peculiarity in the razor-fish of rum that i have not marked in the razor-fish of our eastern coasts. the gills of the animal, instead of bearing the general color of its other parts, like those of the oyster, are of a deep green color, resembling, when examined by the microscope, the fringe of a green curtain. we were told by john stewart, that the expatriated inhabitants of rum used to catch trout by a simple device of ancient standing, which preceded the introduction of nets into the island, and which, it is possible, may in other localities have not only preceded the use of the net, but may have also suggested it: it had at least the appearance of being a first beginning of invention in this direction. the islanders gathered large quantities of heath, and then tying it loosely into bundles, and stripping it of its softer leafage, they laid the bundles across the stream on a little mound held down by stones, with the tops of the heath turned upwards to the current. the water rose against the mound for a foot or eighteen inches, and then murmured over and through, occasioning an expansion among the hard elastic sprays. next a party of the islanders came down the stream, beating the banks and pools, and sending a still thickening shoal of trout before them, that, on reaching the miniature dam formed by the bundles, darted forward for shelter, as if to a hollow bank, and stuck among the slim hard branches, as they would in the meshes of a net. the stones were then hastily thrown off,--the bundles pitched ashore,--the better fish, to the amount not unfrequently of several scores, secured,--and the young fry returned to the stream, to take care of themselves, and grow bigger. we fared richly this evening, after our hard day's labor, on tea and trout; and as the minister had to attend a meeting of the presbytery of skye on the following wednesday, we sailed next morning for glenelg, whence he purposed taking the steamer for portree. winds were light and baffling, and the currents, like capricious friends, neutralized at one time the assistance which they lent us at another. it was dark night ere we had passed isle ornsay, and morning broke as we cast anchor in the bay of glenelg. at ten o'clock the steamer heaved-to in the bay to land a few passengers, and the minister went on board, leaving me in charge of the betsey, to follow him, when the tide set in, through the kyles of skye. chapter ix. kyles of skye--a gneiss district--kyle rhea--a boiling tide--a "take" of sillocks--the betsey's "paces"--in the bay at broadford--rain--island of pabba--description of the island--its geological structure--astrea--polypifers--_gryphæa incurva_--three groups of fossils in the lias of skye--abundance of the petrifactions of pabba--scenery--pabba a "piece of smooth, level england"--fossil shells of pabba--voyage resumed--kyle akin--ruins of castle maoil--a "thornback" dinner--the bunch of deep sea tangle--the caileach stone--kelp furnaces--escape of the betsey from sinking. no sailing vessel attempts threading the kyles of skye from the south in the face of an adverse tide. the currents of kyle rhea care little for the wind-filled sail, and battle at times, on scarce unequal terms, with the steam-propelled paddle. the toward castle this morning had such a struggle to force her way inwards, as may be seen maintained at the door of some place of public meeting during the heat of some agitating controversy, when seat and passage within can hold no more, and a disappointed crowd press eagerly for admission from without. viewed from the anchoring place at glenelg, the opening of the kyle presents the appearance of the bottom of a landlocked bay;--the hills of skye seem leaning against those of the mainland: and the tide-buffeted steamer looked this morning as if boring her way into the earth, like a disinterred mole, only at a rate vastly slower. first, however, with a progress resembling that of the minute-hand of a clock, the bows disappeared amid the heath, then the midships, then the quarter-deck and stern, and then, last of all, the red tip of the sun-brightened union-jack that streamed gaudily behind. i had at least two hours before me ere the betsey might attempt weighing anchor; and, that they might leave some mark, i went and spent them ashore in the opening of glenelg,--a gneiss district, nearly identical in structure with the district of knock and isle ornsay. the upper part of the valley is bare and treeless, but not such its character where it opens to the sea; the hills are richly wooded; and cottages, and cornfields, with here and there a reach of the lively little river, peep out from among the trees. a group of tall roofless buildings, with a strong wall in front, form the central point in the landscape; these are the dismantled berera barracks, built, like the line of forts in the great caledonian valley,--fort george, fort augustus, and fort william,--to overawe the highlands at a time when the loyalty of the highlander pointed to a king beyond the water; but all use for them has long gone by, and they now lie in dreary ruin,--mere sheltering places for the toad and the bat. i found in a loose silt on the banks of the river, at some little distance below tide-mark, a bed of shells and coral, which might belong, i at first supposed, to some secondary formation, but which i ascertained, on examination, to be a mere recent deposit, not so old by many centuries as our last raised sea-beaches. there occurs in various localities on these western coasts, especially on the shores of the island of pabba, a sprig coral, considerably larger in size than any i have elsewhere seen in scotland; and it was from its great abundance in this bed of silt that i was at first led to deem the deposit an ancient one. we weighed anchor about noon, and entered the opening of kyle rhea. vessel after vessel, to the number of eight or ten in all, had been arriving in the course of the morning, and dropping anchor, nearer the opening or farther away, each according to its sailing ability, to await the turn of the tide; and we now found ourselves one of the components of a little fleet, with some five or six vessels sweeping up the kyle before us, and some three or four driving on behind. never, except perhaps in a highland river big in flood, have i seen such a tide. it danced and wheeled, and came boiling in huge masses from the bottom; and now our bows heaved abruptly round in one direction, and now they jerked as suddenly round in another; and, though there blew a moderate breeze at the time, the helm failed to keep the sails steadily full. but whether our sheets bellied out, or flapped right in the wind's eye, on we swept in the tideway, like a cork caught during a thunder shower in one of the rapids of the high street. at one point the kyle is little more than a quarter of a mile in breadth; and here, in the powerful eddy which ran along the shore, we saw a group of small fishing-boats pursuing a shoal of sillocks in a style that blent all the liveliness of the chase with the specific interest of the angle. the shoal, restless as the tides among which it disported, now rose in the boilings of one eddy, now beat the water into foam amid the stiller dimplings of another. the boats hurried from spot to spot wherever the quick glittering scales appeared. for a few seconds, rods would be cast thick and fast, as if employed in beating the water, and captured fish glanced bright to the sun; and then the take would cease, and the play rise elsewhere, and oars would flash out amain, as the little fleet again dashed into the heart of the shoal. as the kyle widened, the force of the current diminished, and sail and helm again became things of positive importance. the wind blew a-head, steady though not strong; and the betsey, with companions in the voyage against which to measure herself, began to show her paces. first she passed one bulky vessel, then another: she lay closer to the wind than any of her fellows, glided more quickly through the water, turned in her stays like lady betty in a minuet; and, ere we had reached kyle akin, the fleet in the middle of which we had started were toiling far behind us, all save one vessel, a stately brig; and just as we were going to pass her too, she cast anchor, to await the change of the tide, which runs from the west during flood at kyle akin, as it runs from the east through kyle rhea. the wind had freshened; and as it was now within two hours of full sea, the force of the current had somewhat abated; and so we kept on our course, tacking in scant room, however, and making but little way. a few vessels attempted following us, but, after an inefficient tack or two, they fell back on the anchoring ground, leaving the betsey to buffet the currents alone. tack followed tack sharp and quick in the narrows, with an iron-bound coast on either hand. we had frequent and delicate turning: now we lost fifty yards, now we gained a hundred. john stewart held the helm; and as none of us had ever sailed the way before, i had the vessel's chart spread out on the companion-head before me, and told him when to wear and when to hold on his way,--at what places we might run up almost to the rock edge, and at what places it was safest to give the land a good offing. hurrah for the free church yacht betsey! and hurrah once more! we cleared the kyle, leaving a whole fleet tide-bound behind us; and, stretching out at one long tack into the open sea, bore, at the next, right into the bay at broadford, where we cast anchor for the night, within two hundred yards of the shore. provisions were running short; and so i had to make a late dinner this evening on some of the razor-fish of rum, topped by a dish of tea. but there is always rather more appetite than food in the country;--such, at least, is the common result under the present mode of distribution: the hunger overlaps and outstretches the provision; and there was comfort in the reflection, that with the razor-fish on which to fall back, it overlapped it but by a very little on this occasion in the cabin of the betsey. the steam-boat passed southwards next morning, and i was joined by my friend the minister a little before breakfast. the day was miserably bad: the rain continued pattering on the skylight, now lighter, now heavier, till within an hour of sunset, when it ceased, and a light breeze began to unroll the thick fogs from off the landscape, volume after volume, like coverings from off a mummy,--leaving exposed in the valley of the lias a brown and cheerless prospect of dark bogs and of debris-covered hills, streaked this evening with downward lines of foam. the seaward view is more pleasing. the deep russet of the interior we find bordered for miles along the edge of the bay with a many-shaded fringe of green; and the smooth grassy island of pabba lies in the midst, a polished gem, all the more advantageously displayed from the roughness of the surrounding setting. we took boat, and explored the lias in our immediate neighborhood till dusk. i had spent several hours among its deposits when on my way to portree, and several hours more when on my journey across the country to the east coast; but it may be well, for the sake of maintaining some continuity of description, to throw together my various observations on the formation, as if made at one time, and to connect them with my exploration of pabba, which took place on the following morning. the rocks of pabba belong to the upper part of the lias; while the lower part may be found leaning to the south, towards the red sandstones of the bay of lucy. taking what seems to be the natural order, i shall begin with the base of the formation first. in the general indentation of the coast, in the opening of which the island of pabba lies somewhat like a long green steam-boat at anchor, there is included a smaller indentation, known as the bay or cove of lucy. the central space in the cove is soft and gravelly; but on both its sides it is flanked by low rocks, that stretch out into the sea in long rectilinear lines, like the foundations of dry-stone fences. on the south side the rocks are red; on the north they are of a bluish-gray color; their hues are as distinct as those of the colored patches in a map; and they represent geological periods that lie widely apart. the red rocks we find laid down in most of our maps as old red, though i am disposed to regard them as of a much higher antiquity than even that ancient system; while the bluish-gray rocks are decidedly liasic.[ ] the cove between represents a deep ditch-like hollow, which occurs in skye, both in the interior and on the sea-shore, in the line of boundary betwixt the red sandstone and the lias; and it "seems to have originated," says m'culloch, "in the decomposition of the exposed parts of the formations at their junction." "hence," he adds, "from the wearing of the materials at the surface, a cavity has been produced, which becoming subsequently filled with rubbish, and generally covered over with a vegetable soil of unusual depth, effectually prevents a view of the contiguous parts." the first strata exposed on the northern side are the oldest liasic rocks anywhere seen in scotland. they are composed chiefly of greenish-colored fissile sandstones and calciferous grits, in which we meet a few fossils, very imperfectly preserved. but the organisms increase as we go on. we see in passing, near a picturesque little cottage,--the only one on the shores of the bay,--a crag of a singularly rough appearance, that projects mole-like from the sward upon the beach, and then descending abruptly to the level of the other strata, runs out in a long ragged line into the sea. the stratum, from two to three feet in thickness, of which it is formed, seems wholly built up of irregularly-formed rubbly concretions, just as some of the garden-walls in the neighborhood of edinburgh are built of the rough scoria of our glass-houses; and we find, on examination, that every seeming concretion in the bed is a perfectly formed coral of the genus astrea. we have arrived at an entire bed of corals, all of one species. their surfaces, wherever they have been washed by the sea, are of great beauty: nothing can be more irregular than the outline of each mass, and yet scarce anything more regular than the sculpturings on every part of it. we find them fretted over with polygons, like those of a honeycomb, only somewhat less mathematically exact, and the centre of every polygon contains its many-rayed star. it is difficult to distinguish between species in some of the divisions of corals: one astrea, recent or extinct, is sometimes found so exceedingly like another of some very different formation or period, that the more modern might almost be deemed a lineal descendant of the more ancient species. with an eye to the fact, i brought with me some characteristic specimens of this astrea[ ] of the lower lias, which i have ranged side by side with the astreæ of the oölite i had found so abundant a twelvemonth before in the neighborhood of helmsdale. in some of the hand specimens, that present merely a piece of polygonal surface, bounded by fractured sides, the difference is not easily distinguishable: the polygonal depressions are generally smaller in the oölitic species, and shallower in the liasic one; but not unfrequently these differences disappear, and it is only when compared in the entire unbroken coral that their specific peculiarities acquire the necessary prominence. the oölitic astrea is of much greater size than the liasic one: it occurs not unfrequently in masses of from two to three feet in diameter; and as its polygons are tubes that converge to the footstalk on which it originally formed, it presents in the average outline a fungous-like appearance; whereas in the smaller liasic coral, which rarely exceeds a foot in diameter, there is no such general convergency of the tubes; and the form in one piece, save that there is a certain degree of flatness common to all, bears no resemblance to the form in another. some of the recent astreæ are of great beauty when inhabited by the living zoöphites whose skeleton framework they compose. every polygonal star in the mass is the house of a separate animal, that, when withdrawn into its cell, presents the appearance of a minute flower, somewhat like a daisy stuck flat to the surface, and that, when stretched out, resembles a small round tower, with a garland of leaves bound round it atop for a cornice. the _astrea viridis_, a coral of the tropics, presents on a ground of velvety brown myriads of deep green florets, that ever and anon start up from the level in their tower-like shape, contract and expand their petals, and then, shrinking back into their cells, straightway became florets again. the lower lias presented in one of its opening scenes, in this part of the world, appearances of similar beauty widely spread. for miles together,--we know not how many,--the bottom of a clear shallow sea was paved with living astreæ: every irregular rock-like coral formed a separate colony of polypora, that, when in motion, presented the appearance of continuous masses of many-colored life, and when at rest, the places they occupied were more thickly studded with the living florets than the richest and most flowery piece of pasture the reader ever saw, with its violets or its daisies. and mile beyond mile this scene of beauty stretched on through the shallow depths of the liasic sea. the calcareous framework of most of the recent astreæ are white; but in the species referred to,--the _astrea viridis_,--it is of a dark-brown color. it is not unworthy of remark, in connection with these facts, that the oölitic astrea of helmsdale occurs as a white, or, when darkest, as a cream-colored petrifaction; whereas the liasic astrea of skye is invariably of a deep earthy hue. the one was probably a white, the other a dingy-colored coral. the liasic bed of astreæ existed long enough here to attain a thickness of from two to three feet. mass rose over mass,--the living upon the dead,--till at length, by a deposit of mingled mud and sand,--the effect, mayhap, of some change of currents, induced we know not how,--the innumerable polypedes of the living surface were buried up and killed, and then, for many yards, layer after layer of a calciferous grit was piled over them. the fossils of the grit are few and ill preserved; but we occasionally find in it a coral similar to the astrea of the bed below, and, a little higher up, in an impure limestone, specimens, in rather indifferent keeping, of a genus of polypifer which somewhat resembles the turbinolia of the mountain limestone. it presents in the cross section the same radiated structure as the _turbinolia fungites_, and nearly the same furrowed appearance in the longitudinal one; but, seen in the larger specimens, we find that it was a branched coral, with obtuse forky boughs, in each of which, it is probable, from their general structure, there lived a single polype. it may have been the resemblance which these bear, when seen in detached branches, to the older caryophyllia, taken in connection with the fact that the deposit in which they occur rests on the ancient red sandstone of the district, that led m'culloch to question whether this fossiliferous formation had not nearly as clear a claim to be regarded as an analogue of the carboniferous limestone of england as of its lias; and hence he contented himself with terming it simply the gryphite limestone. sir r. murchison, whose much more close and extensive acquaintance with fossils enabled him to assign to the deposit its true place, was struck, however, with the general resemblance of its polypifers to "those of the madreporite limestone of the carboniferous series." these polypifers occur in only the lower lias of skye.[ ] i found no corals in its higher beds, though these are charged with other fossils, more characteristic of the formation, in vast abundance. in not a few of the middle strata, composed of a mud-colored fissile sandstone, the gryphites lie as thickly as currants in a christmas cake; and as they weather white, while the stone in which they are embedded retains its dingy hue, they somewhat remind one of the white-lead tears of the undertaker mottling a hatchment of sable. in a fragment of the dark sandstone, six inches by seven, which i brought with me, i reckon no fewer than twenty-two gryphites; and it forms but an average specimen of the bed from which i detached it. by far the most abundant species is that not inelegant shell so characteristic of the formation, the _gryphæa incurva_. we find detached specimens scattered over the beach by hundreds, mixed up with the remains of recent shells, as if the _gryphæa incurva_ were a recent shell too. they lie, bleached white by the weather, among the valves of defunct oysters and dead buccinidæ; and, from their resemblance to lamps cast in the classic model, remind one, in the corners where they have accumulated most thickly, of the old magician's stock in trade, who wiled away the lamp of aladdin from aladdin's simple wife. the _gryphæa obliquita_ and _gryphæa m'cullochii_ also occur among these middle strata of the lias, though much less frequently than the other. we, besides, found in them at least two species of pecten, with two species of terebratula,--the one smooth, the other sulcated; a bivalve resembling a donax; another bivalve, evidently a gervillia, though apparently of a species not yet described; and the ill-preserved rings of large ammonites, from ten inches to a foot in diameter. towards the bottom of the bay the fossils again become more rare, though they re-appear once more in considerable abundance as we pass along its northern side; but in order to acquaint ourselves with the upper organisms of the formation, we have to take boat and explore the northern shores of pabba. the lias of skye has its three distinct groups of fossils: its lower coraline group, in which the astrea described is most abundant; its middle group, in which the _gryphæa incurva_ occurs by millions; and its upper group, abounding in ammonites, nautili, pinnæ, and serpulæ. friday made amends for the rains and fogs of its disagreeable predecessor: the morning rose bright and beautiful, with just wind enough to fill, and barely fill, the sail, hoisted high, with miser economy, that not a breath might be lost; and, weighing anchor, and shaking out all our canvass, we bore down on pabba, to explore. this island, so soft in outline and color, is formidably fenced round by dangerous reefs; and, leaving the betsey in charge of john stewart and his companion, to dodge on in the offing, i set out with the minister in our little boat, and landed on the north-eastern side of the island, beside a trap-dyke that served us as a pier. he would be a happy geologist who, with a few thousands to spare, could call pabba his own. it contains less than a square mile of surface; and a walk of little more than three miles and a half along the line where the waves break at high water brings the traveller back to his starting point; and yet, though thus limited in area, the petrifactions of its shores might of themselves fill a museum. they rise by thousands and tens of thousands on the exposed planes of its sea-washed strata, standing out in bold relief, like sculpturings on ancient tombstones, at once mummies and monuments,--the dead and the carved memorials of the dead. every rock is a tablet of hieroglyphics, with an ascertained alphabet; every rolled pebble a casket with old pictorial records locked up within. trap-dykes, beyond comparison finer than those of the water of leith, which first suggested to hutton his theory, stand up like fences over the sedimentary strata, or run out like moles far into the sea. the entire island, too, so green, rich, and level, is itself a specimen illustrative of the effect of geologic formation on scenery. we find its nearest neighbor,--the steep, brown, barren island of longa, which is composed of the ancient red sandstone of the district,--differing as thoroughly from it in aspect as a bit of granite differs from a bit of clay-slate; and the whole prospect around, save the green liasic strip that lies along the bottom of the bay of broadford, exhibits, true to its various components, plutonic or sedimentary, a character of picturesque roughness or bold sublimity. the only piece of smooth, level england, contained in the entire landscape, is the fossil-mottled island of pabba. we were first struck, on landing this morning, by the great number of pinnæ embedded in the strata,--shells varying from five to ten inches in length,--one species of the common flat type, exemplified in the existing _pinna sulcata_, and another nearly quadrangular, in the cross section, like the _pinna lanceolata_ of the scarborough limestone. the quadrangular species is more deeply crisped outside than the flat one. both species bear the longitudinal groove in the centre, and when broken across, are found to contain numerous smaller shells,--terebratulæ of both the smooth and sulcated kinds, and a species of minute smooth pecten resembling the _pecten demissus_, but smaller. the pinnæ, ere they became embedded in the original sea-bottom, long since hardened into rock around them, were, we find, dead shells, into which, as into the dead open shells of our existing beaches, smaller shells were washed by the waves. our recent pinnæ are all sedentary shells, some of them full two feet in length, fastened to their places on their deep-sea floors by flowing silky byssi,--cables of many strands,--of which beautiful pieces of dress, such as gloves and hose, have been manufactured. an old french naturalist, the abbe le pluche, tells us that "the pinna with its fleshy tongue" (foot),--a rude inefficient looking implement for work so nice,--"spins such threads as are more valuable than silk itself, and with which the most beautiful stuffs that ever were seen have been made by sicilian weavers." gloves made of the byssus of recent pinnæ may be seen in the british museum. associated with the numerous pinnæ of pabba we found a delicately-formed modiola, a small ostrya, plagiostoma, terebratula, several species of pectens, a triangular univalve resembling a trochus, innumerable groups of serpulæ, and the star-like joints of pentacrinites. the gryphæ are also abundant, occurring in extensive beds; and belemnites of various species lie as thickly scattered over the rock as if they had been the spindles of a whole kingdom thrown aside in consequence of some such edict framed to put them down as that passed by the father of the sleeping beauty. we find, among the detached masses of the beach, specimens of nautilus, which, though rarely perfect, are sufficiently so to show the peculiarities of the shell; and numerous ammonites project in relief from almost every weathered plane of the strata. these last shells, in the tract of shore which we examined, are chiefly of one species,--the _ammonites spinatus_,--one of which, considerably broken, the reader may find figured in sowerby's "mineral conchology," from a specimen brought from pabba sixteen years ago by sir r. murchison. it is difficult to procure specimens tolerably complete. we find bits of outer rings existing as limestone, with every rib sharply preserved, but the rest of the fossil lost in the shale. i succeeded in finding but two specimens that show the inner whorls. they are thickly ribbed; and the chief peculiarity which they exhibit, not so directly indicated by mr. sowerby's figure, is, that while the ribs of the outer whorl are broad and deep, as in the _ammonites obtusus_, they suddenly change their character, and become numerous and narrow in the inner whorls, as in the _ammonites communis_. the tide began to flow, and we had to quit our explorations, and return to the betsey. the little wind had become less, and all the canvas we could hang out enabled us to draw but a sluggish furrow. the stern of the betsey "wrought no buttons" on this occasion; but she had a good tide under her keel; and ere the dinner-hour we had passed through the narrows of kyle akin. the village of this name was designed by the late lord m'donald for a great seaport town; but it refused to grow; and it has since become a gentleman in a small way, and does nothing. it forms, however, a handsome group of houses, pleasantly situated on a flat green tongue of land, on the skye side, just within the opening of the kyle; and there rises on an eminence beyond it a fine old tower, rent open, as if by an earthquake, from top to bottom, which forms one of the most picturesque objects i have almost ever seen in a landscape. there are bold hills all around, and rocky islands, with the ceaseless rush of tides in front; while the cloven tower, rising high over the shore, is seen, in threading the kyles, whether from the south or north, relieved dark against the sky, as the central object in the vista. we find it thus described by the messrs. anderson of inverness, in their excellent "guide book,"--by far the best companion of the kind with which the traveller who sets himself to explore our scottish highlands can be provided. "close to the village of kyle akin are the ruins of an old square keep, called castle muel or maoil, the walls of which are of a remarkable thickness. it is said to have been built by the daughter of a norwegian king, married to a mackinnon or macdonald, for the purpose of levying an impost on all vessels passing the kyles, excepting, says the tradition, those of her own country. for the more certain exaction of this duty, she is reported to have caused a strong chain to be stretched across from shore to shore; and the spot in the rocks to which the terminal links were attached is still pointed out." it was high time for us to be home. the dinner hour came; but, in meet illustration of the profound remark of trotty-veck, not the dinner. we had been in a cold moderate district, whence there came no half-dozens of eggs, or whole dozens of trout, or pailfuls of razor-fish, and in which hard cabin-biscuit cost us sixpence per pound. and now our stores were exhausted, and we had to dine as best we could, on our last half-ounce of tea, sweetened by our last quarter of a pound of sugar. i had marked, however, a dried thornback hanging among the rigging. it had been there nearly three weeks before, when i came first aboard, and no one seemed to know for how many weeks previous; for as it had come to be a sort of fixture in the vessel, it could be looked at without being seen. but necessity sharpens the discerning faculty, and on this pressing occasion i was fortunate enough to see it. it was straightway taken down, skinned, roasted, and eaten; and, though rather rich in ammonia,--a substance better suited to form the food of the organisms that do not unite sensation to vitality, than organisms so high in the scale as the minister and his friend,--we came deliberately to the opinion, that on the whole, we could scarce have dined so well on one of major bellenden's jack-boots,--"so thick in the soles," according to jenny dennison, "forby being tough in the upper leather." the tide failed us opposite the opening of loch alsh; the wind, long dying, at length died out into a dead calm; and we cast anchor in ten fathoms water, to wait the ebbing current that was to carry us through kyle rhea. the ebb-tide set in about half an hour after sunset; and in weighing anchor to float down the kyle,--for we still lacked wind to sail down it,--we brought up from below, on one of the anchor-flukes, an immense bunch of deep-sea tangle, with huge soft fronds and long slender stems, that had lain flat on the rocky bottom, and had here and there thrown out roots along its length of stalk, to attach itself to the rock, in the way the ivy attaches itself to the wall. among the intricacies of the true roots of the bunch, if one may speak of the true roots of an alga, i reckoned from eighteen to twenty different forms of animal life,--flustræ, sertulariæ, serpulæ, anomiæ, modiolæ, astarte, annelida, crustacea, and radiata. among the crustaceans i found a female crab of a reddish-brown color, considerably smaller than the nail of my small finger, but fully grown apparently, for the abdominal flap was loaded with spawn; and among the echinoderms, a brownish-yellow sea-urchin about the size of a pistol-bullet, furnished with comparatively large but thinly-set spines. there is a dangerous rock in the kyle rhea, the caileach stone, on which the commissioners for the northern lighthouses have stuck a bit of board about the size of a pot-lid, which, as it is known to be there, and as no one ever sees it after sunset, is really very effective, considering how little it must have cost the country, in wrecking vessels. i saw one of its victims, the sloop of an honest methodist, in whose bottom the caileach had knocked out a hole, repairing at isle ornsay; and i was told, that if i wished to see more, i had only just to wait a little. the honest methodist, after looking out in vain for the bit of board, was just stepping into the shrouds, to try whether he could not see the rock on which the bit of board is placed, when all at once his vessel found out both board and rock for herself. we also had anxious looking out this evening for the bit of board: one of us thought he saw it right a-head; and when some of the others were trying to see it too, john stewart succeeded in discovering it half a pistol-shot astern. the evening was one of the loveliest. the moon rose in cloudy majesty over the mountains of glenelg, brightening as it rose, till the boiling eddies around us curled on the darker surface in pale circlets of light, and the shadow of the betsey lay as sharply defined on the brown patch of calm to the larboard as if it were her portrait taken in black. immediately at the water-edge, under a tall dark hill, there were two smouldering fires, that now shot up a sudden tongue of bright flame, and now dimmed into blood-red specks, and sent thick strongly-scented trails of smoke athwart the surface of the kyle. we could hear, in the calm, voices from beside them, apparently those of children; and learned that they indicated the places of two kelp-furnaces,--things which have now become comparatively rare along the coasts of the hebrides. there was the low rush of tides all around, and the distant voices from the shore, but no other sounds; and, dim in the moonshine, we could see behind us several spectral-looking sails threading their silent way through the narrows, like twilight ghosts traversing some haunted corridor. it was late ere we reached the opening of isle ornsay; and as it was still a dead calm we had to tug in the betsey to the anchoring ground with a pair of long sweeps. the minister pointed to a low-lying rock on the left-hand side of the opening,--a favorite haunt of the seal. "i took farewell of the betsey there last winter," he said. "the night had worn late, and was pitch dark; we could see before us scarce the length of our bowsprit; not a single light twinkled from the shore; and, in taking the bay, we ran bump on the skerry, and stuck fast. the water came rushing in, and covered over the cabin-floor. i had mrs. swanson and my little daughter aboard with me, with one of our servant-maids who had become attached to the family, and insisted on following us from eigg; and, of course, our first care was to get them ashore. we had to land them on the bare uninhabited island yonder, and a dreary enough place it was at midnight, in winter, with its rocks, bogs, and heath, and with a rude sea tumbling over the skerries in front; but it had at least the recommendation of being safe, and the sky, though black and wild, was not stormy. i had brought two lanterns ashore: the servant girl, with the child in her lap, sat beside one of them, in the shelter of a rock; while my wife, with the other, went walking up and down along a piece of level sward yonder, waving the light, to attract notice from the opposite side of the bay. but though it was seen from the windows of my own house by an attached relative, it was deemed merely a singularly-distinct apparition of will o' the wisp, and so brought us no assistance. meanwhile we had carried out a kedge astern of the betsey, as the sea was flowing at the time, to keep her from beating in over the rocks; and then, taking our few movables ashore, we hung on till the tide rose, and, with our boat alongside ready for escape, succeeded in warping her into deep water, with the intention of letting her sink somewhere beyond the influence of the surf, which, without fail, would have broken her up on the skerry in a few hours, had we suffered her to remain there. but though, when on the rock, the tide had risen as freely over the cabin sole inside as over the crags without, in the deep water the betsey gave no sign of sinking. i went down to the cabin; the water was knee-high on the floor, dashing against bed and locker, but it rose no higher;--the enormous leak had stopped, we knew not how; and, setting ourselves to the pump, we had in an hour or two a clear ship. the betsey is clinker-built below. the elastic oak planks had yielded inwards to the pressure of the rock, tearing out the fastenings, and admitted the tide at wide yawning seams; but no sooner was the pressure removed, than out they sprung again into their places, like bows when the strings are slackened; and when the carpenter came to overhaul, he found he had little else to do than to remove a split plank, and to supply a few dozens of drawn nails." chapter x. isle ornsay--the sabbath--a sailor-minister's sermon for sailors--the scuir sermon--loch carron--groups of moraines--a sheep district--the editor of the _witness_ and the establishment clergyman--dingwall--conon-side revisited--the pond and its changes--new faces--the stonemason's mark--the burying ground of urquhart--an old acquaintance--property qualification for voting in scotland--montgerald sandstone quarries--geological science in cromarty--the danes at cromarty--the danish professor and the "old red sandstone"--harmonizing tendencies of science. the anchoring ground at isle ornsay was crowded with coasting vessels and fishing boats; and when the sabbath came round, no inconsiderable portion of my friend's congregation was composed of sailors and fishermen. his text was appropriate,--"he bringeth them into their desired haven;" and as his sea-craft and his theology were alike excellent, there were no incongruities in his allegory, and no defects in his mode of applying it, and the seamen were hugely delighted. john stewart, though less a master of english than of many other things, told me he was able to follow the minister from beginning to end,--a thing he had never done before at an english preaching. the sea portion of the sermon, he said, was very plain: it was about the helm, and the sails, and the anchor, and the chart, and the pilot,--about rocks, winds, currents, and safe harborage; and by attending to this simpler part of it, he was led into the parts that were less simple, and so succeeded in comprehending the whole. i would fain see this unique discourse, preached by a sailor minister to a sailor congregation, preserved in some permanent form, with at least one other discourse,--of which i found trace in the island of eigg, after the lapse of more than a twelvemonth,--that had been preached about the time of the disruption, full in sight of the scuir, with its impregnable hill-fort, and in the immediate neighborhood of the cave of frances, with its heaps of dead men's bones. one note stuck fast to the islanders. in times of peril and alarm, said the minister, the ancient inhabitants of the island had two essentially different kinds of places in which they sought security; they had the deep, unwholesome cave, shut up from the light and the breath of heaven, and the tall rock summit, with its impregnable fort, on which the sun shone and the wind blew. much hardship might no doubt be encountered on the one, when the sky was black with tempest, and rains beat, or snows descended; but it was found associated with no story of real loss or disaster,--it had kept safe all who had committed themselves to it; whereas, in the close atmosphere of the other there was warmth, and, after a sort, comfort; and on one memorable day of trouble the islanders had deemed it the preferable sheltering place of the two. and there survived mouldering skeletons and a frightful tradition, to tell the history of their choice. places of refuge of these very opposite kinds, said the minister, continuing his allegory, are not peculiar to your island; never was there a day or a place of trial in which they did not advance their opposite claims: they are advancing them even now all over the world. the one kind you find described by one great prophet as low-lying "refuges of lies," over which the desolating "scourge must pass," and which the destroying "waters must overflow;" while the true character of the other may be learned from another great prophet, who was never weary of celebrating his "rock and his fortress." "wit succeeds more from being happily addressed," says goldsmith, "than even from its native poignancy." if my friend's allegory does not please quite as well in print and in english as it did when delivered _viva voce_ in gaelic, it should be remembered that it was addressed to an out-door congregation, whose minds were filled with the consequences of the disruption,--that the bones of _uamh fraingh_ lay within a few hundred yards of them,--and that the scuir, with the sun shining bright on its summit, rose tall in the background, scarce a mile away. on monday i spent several hours in reëxploring the lias of lucy bay and its neighborhood, and then walked on to kyle-akin, where i parted from my friend mr. swanson, and took boat for loch carron. the greater part of the following day was spent in crossing the country to the east coast in the mail-gig, through long dreary glens, and a fierce storm of wind and rain. in the lower portion of the valley occupied by the river carron, i saw at least two fine groups of moraines. one of these, about a mile and a half above the parish manse, marks the place where a glacier, that had once descended from a hollow amid the northern range of hills, had furrowed up the gravel and earth before it in long ridges, which we find running nearly parallel to the road; the other group, which lies higher up the valley, and seems of considerably greater extent, indicates where one of those river-like glaciers that fill up long hollows, and impel their irresistible flood downwards, slow as the hour-hand of a time-piece, had terminated towards the sea. i could but glance at the appearances as the gig drove past, and point them out to a fellow passenger, the establishment minister of----, remarking, at the same time, how much more dreary the prospect must have seemed than even it did to-day, though the fog was thick and the drizzle disagreeable, when the lateral hollows on each side were blocked up with ice, and overhanging glaciers, that ploughed the rock bare in their descent, glistened on the bleak hill-sides. i wore a gray maud over a coat of rough russet, with waist-coat and trowsers of plaid; and the minister, who must have taken me, i suppose, for a southland shepherd looking out for a farm, gave me much information of a kind i might have found valuable had such been my condition and business, regarding the various districts through which we passed. on one high-lying farm, the grass, he said, was short and thin, but sweet and wholesome, and the flocks throve steadily, and were never thinned by disease; whereas on another farm, that lay along the dank bottom of a valley, the herbage was rank and rich, and the sheep fed and got heavy, but braxy at the close of autumn fell upon them like a pestilence, and more than neutralized to the farmer every advantage of the superior fertility of the soil. it was not uninteresting, even for one not a sheep-farmer, to learn that the life of the sheep is worth fewer years' purchase in one little track of country than in another adjacent one; and that those differences in the salubrity of particular spots which obtain in other parts of the world in regard to our own species, and which make it death to linger on the luxuriant river-side, while on the arid plain or elevated hill-top there is health and safety, should exist in contiguous walks in the highlands of scotland in reference to some of the inferior animals. the minister and i became wonderfully good friends for the time. all the seats in the gig, both back and front, had been occupied ere he had taken his passage, and the postman had assigned him a miserable place on the narrow elevated platform in the middle, where he had to coil himself up like a hedgehog in its hole, sadly to the discomfort of limbs still stout and strong, but stiffened by the long service of full seventy years. and, as in the case made famous by cowper, of the "softer sex" and the old-fashioned iron-cushioned arm-chairs, the old man had, as became his years, "'gan murmur." i contrived, by sitting on the edge of the gig on the one side, and by getting the postman to take a similar seat on the other, to find room for him in front; and there, feeling he had not to do with savages, he became kindly and conversible. we beat together over a wide range of topics;--the scotch banks, and sir robert peel's intentions regarding them,--the periodical press of scotland,--the edinburgh literati,--the free church even: he had been a consistent moderate all his days, and disliked renegades, he said; and i, of course, disliked renegades too. we both remembered that, though civilized nations give quarter to an enemy overpowered in open fight, they are still in the habit of shooting deserters. in short, we agreed on a great many different matters; and, by comparing notes, we made the best we could of a tedious journey and a very bad day. at the inn at garve, a long stage from dingwall, we alighted, and took the road together, to straighten our stiffened limbs, while the post man was engaged in changing horses. the minister stopped short in the middle of a discussion. we are not on equal terms, he said: you know who i am, and i don't know you: we did not start fair at the beginning, but let us start fair now. ah, we have agreed hitherto, i replied; but i know not how we are to agree when you know who i am: are you sure you will not be frightened? frightened! said the minister sturdily; no, by no man. then, i am the editor of the _witness_. there was a momentary pause. "well," said the minister, "it's all the same: i'm glad we should have met. give me, man, a shake of your hand." and so the conversation went on as before till we parted at dingwall,--the establishment clergyman wet to the skin, the free church editor in no better condition; but both, mayhap, rather less out of conceit with the ride than if it had been ridden alone. i had intended passing at least two days in the neighborhood of dingwall, where i proposed renewing an acquaintance, broken off for three-and-twenty years, with those bituminous shales of strathpeffer in which the celebrated mineral waters of the valley take their rise,--the old red conglomerate of brahan, the vitrified fort of knockferrel, the ancient tower of fairburn, above all, the pleasure-grounds of conon-side. i had spent the greater portion of my eighteenth and nineteenth years in this part of the country; and i was curious to ascertain to what extent the man in middle life would verify the observations of the lad,--to recall early incidents, revisit remembered scenes, return on old feelings, and see who were dead and who were alive among the casual acquaintances of nearly a quarter of a century ago. the morning of wednesday rose dark with fog and rain, but the wind had fallen; and as i could not afford to miss seeing conon-side, i sallied out under cover of an umbrella. i crossed the bridge, and reached the pleasure-grounds of conon-house. the river was big in flood: it was exactly such a river conon as i had lost sight of in the winter of ; and i had to give up all hope of wading into its fords, as i used to do early in the autumn of that year, and pick up the pearl muscles that lie so thickly among the stones at the bottom. i saw, however, amid a thicket of bushes by the river-side, a heap of broken shells, where some herd-boy had been carrying on such a pearl fishery as i had sometimes used to carry on in my own behalf so long before; and i felt it was just something to see it. the flood eddied past, dark and heavy, sweeping over bulwark and bank. the low-stemmed alders that rose on islet and mound seemed shorn of half their trunks in the tide; here and there an elastic branch bent to the current, and rose and bent again; and now a tuft of withered heath came floating down, and now a soiled wreath of foam. how vividly the past rose up before me!--boyish day-dreams forgotten for twenty years,--the fossils of an early formation of mind, produced at a period when the atmosphere of feeling was warmer than now, and the immaturities of the mental kingdom grew rank and large, like the ancient cryptogamiæ, and bore no specific resemblance to the productions of a present time. i had passed in the neighborhood the first season i anywhere spent among strangers, at an age when home is not a country, nor a province even, but simply a little spot of earth inhabited by friends and relatives; and the rude verses, long forgotten, in which my joy had found vent when on the eve of returning to that home,--a home little more than twenty miles away,--came chiming as freshly into my memory as if scarce a month had passed since i had composed them beside the conon.[ ] three-and-twenty years form a large portion of the short life of man,--one-third, as nearly as can be expressed in unbroken numbers, of the entire term fixed by the psalmist, and full one-half, if we strike off the twilight periods of childhood and immature youth, and of senectitude weary of its toils. i found curious indications among the grounds of conon-side, of the time that had elapsed since i had last seen them. there was a rectangular pond in a corner of a moor, near the public road, inhabited by about a dozen voracious, frog-eating pike, that i used frequently to visit. the water in the pond was exceedingly limpid; and i could watch from the banks every motion of the hungry, energetic inmates. and now i struck off from the river-side by a narrow tangled pathway, to visit it once more. i could have found out the place blindfold: there was a piece of flat brown heath that stretched round its edges, and a mossy slope that rose at its upper side, at the foot of which the taste of the proprietor had placed a rustic chair. the spot, though itself bare and moory, was nearly surrounded by wood, and looked like a clearing in an american forest. there were lines of graceful larches on two of its sides, and a grove of vigorous beeches that directly fronted the setting sun on a third; and i had often found it a place of delightful resort, in which to saunter alone in the calm summer evenings, after the work of the day was over. such was the scene as it existed in my recollection. i came up to it this day through dripping trees, along a neglected pathway; and found, for the open space and the rectangular pond, a gloomy patch of water in the middle of a tangled thicket, that rose some ten or twelve feet over my head. what had been bare heath a quarter of a century before had become a thick wood; and i remembered, that when i had been last there, the open space had just been planted with forest-trees, and that some of the taller plants rose half-way to my knee. human lifetimes, as now measured, are not intended to witness both the seed-times and the harvests of forests,--both the planting of the sapling, and the felling of the huge tree into which it has grown; and so the incident impressed me strongly. it reminded me of the sage shalum in addison's antediluvian tale, who became wealthy by the sale of his great trees, two centuries after he had planted them. i pursued my walk, to revisit another little patch of water which i had found so very entertaining a volume three-and-twenty years previous, that i could still recall many of its lessons; but the hand of improvement had been busy among the fields of conon-side; and when i came up to the spot which it had occupied, i found but a piece of level arable land, bearing a rank swathe of grass and clover.[ ] not a single individual did i find on the farm who had been there twenty years before. i entered into conversation with one of the ploughmen, apparently a man of some intelligence; but he had come to the place only a summer or two previous, and the names of most of his predecessors sounded unfamiliar in his ears: he knew scarce anything of the old laird or his times, and but little of the general history of the district. the frequent change of servants incident to the large-farm system has done scarce less to wear out the oral antiquities of the country than has been done by its busy ploughs in obliterating antiquities of a more material cast. the mythologic legend and traditionary story have shared the same fate, through the influence of the one cause, which has been experienced by the sepulchral tumulus and the ancient encampment under the operations of the other. i saw in the pillars and archways of the farm-steading some of the hewn stones bearing my own mark,--an anchor, to which i used to attach a certain symbolical meaning; and i pointed them out to the ploughman. i had hewn these stones, i said, in the days of the old laird, the grandfather of the present proprietor. the ploughman wondered how a man still in middle life could have such a story to tell. i must surely have begun work early in the day, he remarked, which was perhaps the best way for getting it soon over. i remembered having seen similar markings on the hewn-work of ancient castles, and of indulging in, i daresay, idle enough speculations regarding what was doing at court and in the field, in scotland and elsewhere, when the old long-departed mechanics had been engaged in their work. when this mark was affixed, i have said, all scotland was in mourning for the disaster at flodden, and the folk in the work-shed would have been, mayhap, engaged in discussing the supposed treachery of home, and in arguing whether the hapless james had fallen in battle, or gone on a pilgrimage to merit absolution for the death of his father. and when this other more modern mark was affixed, the gowrie conspiracy must have been the topic of the day, and the mechanics were probably speculating,--at worst not more doubtfully than the historians have done after them,--on the guilt or innocence of the ruthvens. it now rose curiously enough in memory, that i was employed in fashioning one of the stones marked by the anchor,--a corner stone in a gate-pillar,--when one of my brother apprentices entered the work-shed, laden with a bundle of newly sharpened irons from the smithy, and said he had just been told by the smith that the great napoleon bonaparte was dead. i returned to the village of conon bridge, through the woods of conon house. the day was still very bad: the rain pattered thick on the leaves, and fell incessantly in large drops on the pathways. there is a solitary, picturesque burying-ground on a wooded hillock beside the river, with thick dark woods all around it,--one of the two burying-grounds of the parish of urquhart,--which i would fain have visited, but the swollen stream had risen high around, converting the hillock into an island, and forbade access. i had spent many an hour among the tombs. they are few and scattered, and of the true antique cast,--roughened with death's heads, and cross-bones, and rudely sculptured armorial bearings; and on a broken wall, that marked where the ancient chapel once had stood, there might be seen, in the year , a small, badly-cut sun-dial, with its iron gnomon wasted to a saw-edged film, that contained more oxide than metal. the only fossils described in my present chapter are fossils of mind; and the reader will, i trust, bear with me should i produce one fossil more of this somewhat equivocal class. it has no merit to recommend it,--it is simply an organism of an immature intellectual formation, in which, however, as in the carboniferous period, there was provision made for the necessities of an after time.[ ] if a young man born on the wrong side of the tweed for _speaking_ english, is desirous to acquire the ability of _writing_ it, he should by all means begin by trying to write it in verse. i passed, on my return to dingwall, through the village of conon bridge; and remembering that one of the masons who had hewn beside me in the work-shed so many years before lived in the village at the time, i went direct to the house he had inhabited, to see whether he might not be there still. it was a low-roofed domicile beside the river, but in the days of my old acquaintance it had presented an appearance of great comfort and neatness; and as there now hung an air of neglect about it, i inferred that it had found some other tenant. i inquired, however, at the door, and was informed that mr. ---- now lived higher up the street. i would find him, it was added, in the best house on the right-hand side,--the house with a hewn front, and a shop in it. he kept the shop, and was the owner of the house, and had another house besides, and was one of the elders of the free church in urquhart. such was the standing of my old acquaintance the journeyman mason of twenty-three years ago. he had been, when i knew him, a steady, industrious, religious man,--with but one exception the only contributor to missionary and bible societies among a numerous party of workmen; and he was now occupying a respectable place in his village, and was one of the voters of the county. let chartism assert what it pleases on the one hand, and toryism what it may on the other, the property-qualification of the reform bill is essentially a good one for such a country as scotland. in our cities it no doubt extends the political franchise to a fluctuating class, ill hafted in society, who possess it one year and want it another; but in our villages and smaller towns it hits very nearly the right medium for forming a premium on steady industry and character, and for securing that at least the mass of those who possess it should be sober-minded men, with a stake in the general welfare. in running over the histories of the various voters in one of our smaller towns, i found that nearly one-half of the whole had, like my old comrade at conon bridge, acquired for themselves, through steady and industrious habits, the qualification from which they derive their vote. my companion failed to recognize in the man turned of forty the smooth-cheeked stripling of eighteen, with whom he had wrought so long before. i soon succeeded, however, in making good my claim to his acquaintance. he had previously established the identity of the editor of his newspaper with his quondam fellow-workman, and a single link more was all the chain wanted. we talked over old matters for half an hour. his wife, a staid respectable matron, who, when i had been last in the district, was exactly such a person as her eldest daughter, showed me an encyclopædia, with colored prints, which she wished to send, if she knew but how, to the free church library. i walked with him through his garden, and saw trees loaded with yellow-cheeked pippins, where i had once seen only unproductive heath, that scantily covered a barren soil of ferruginous sand, and unwillingly declining an invitation to wait tea,--for a previous engagement interfered,--i took leave of the family, and returned to dingwall. the following morning was gloomy, and threatened rain; and giving up my intention of exploring strathpeffer, i took the morning coach for invergordon, and then walked to cromarty, where i arrived just in time for breakfast. i marked, from the top of the coach, about two miles to the north-east of dingwall, beds of a deep gray sandstone, identical in color and appearance with some of the gray sandstones of the middle old red of forfarshire, and learned that quarries had lately been opened in these beds near montgerald. the old red sandstone lies in immense development on the flanks of ben-wevis; and it is just possible that the analogue of the gray flagstones of forfar may be found among its upper beds. if so, the quarriers should be instructed to look hard for organic remains,--the broad-headed cephalaspis, so characteristic of the formation, and the huge crustacean, its contemporary, that disported in plates large as those of the steel mail of the later ages of chivalry. the geologists of dingwall,--if dingwall has yet got its geologists,--might do well to attempt determining the point. i found the science much in advance in cromarty, especially among the ladies,--its great patronizers and illustrators everywhere,--and, in not a few localities, extensive contributors to its hoards of fact. just as i arrived, there was a pic-nic party of young people setting out for the lias of shandwick. they spent the day among its richly fossiliferous shales and limestones, and brought back with them in the evening, ammonites and gryphites enough to store a museum. cromarty had been visited during the summer by geologists speaking a foreign tongue, but thoroughly conversant with the occult yet common language of the rocks, and deeply interested in the stories which the rocks told. the vessels in which the crown prince of denmark voyaged to the faroe isles had been for some time in the bay; and the danes, his companions, votaries of the stony science, zealously plied chisel and hammer among the old red sandstones of the coast. a townsman informed me that he had seen a danish professor hammering like the tutelary thor of his country among the nodules in which i had found the first pterichthys and first diplacanthus ever disinterred; and that the professor, ever and anon as he laid open a specimen, brought it to a huge smooth boulder, on which there lay a copy of the "old red sandstone," to ascertain from the descriptions and prints its family and name. shall i confess that the circumstance gratified me exceedingly? there are many elements of discord among mankind in the present time, both at home and abroad,--so many, that i am afraid we need entertain no hope of seeing an end, in at least our day, to controversy and war. and we should be all the better pleased, therefore, to witness the increase of those links of union,--such as the harmonizing bonds of a scientific sympathy,--the tendency of which is to draw men together in a kindly spirit, and the formation of which involves no sacrifice of principle, moral or religious. i do not think that the foreigner, after geologizing in my company, would have had any very vehement desire, in the event of a war, to cut me down, or to knock me on the head. i am afraid this chapter would require a long apology, and for a long apology space is wanting. but there will be no egotism, and much geology, in my next. chapter xi. ichthyolite beds--an interesting discovery--two storeys of organic remains in the old red sandstone--ancient ocean of lower old red--two great catastrophes--ancient fish scales--their skilful mechanism displayed by examples--bone lips--arts of the slater and tiler as old as old red sandstone--jet trinkets--flint arrow-heads--vitrified forts of scotland--style of grouping lower old red fossils--illustration from cromarty fishing phenomena--singular remains of holoptychius--ramble with mr. robert dick--color of the planet mars--tombs never dreamed of by hervey--skeleton of the bruce--gigantic holoptychius--"coal money currency"--upper boundary of lower old red--every one may add to the store of geological facts--discoveries of messrs. dick and peach. i spent one long day in exploring the ichthyolite beds on both sides the cromarty frith, and another long day in renewing my acquaintance with the liasic deposit at shandwick. in beating over the lias, though i picked up a few good specimens, i acquired no new facts; but in re-examining the old red sandstone and its organisms i was rather more successful. i succeeded in eliciting some curious points not yet recorded, which, with the details of an interesting discovery made in the far north in this formation, i may be perhaps able to weave into a chapter somewhat more geological than my last. some of the readers of my little work on the old red sandstone will perhaps remember that i described the organisms of that ancient system as occurring in the neighborhood of cromarty mainly on one platform, raised rather more than a hundred feet over the great conglomerate; and that on this platform, as if suddenly overtaken by some wide-spread catastrophe, the ichthyolites lie by thousands and tens of thousands, in every attitude of distortion and terror. we see the spiked wings of the pterichthys elevated to the full, as they had been erected in the fatal moment of anger and alarm, and the bodies of the cheirolepis and cheiracanthus bent head to tail, in the stiff posture into which they had curled when the last pang was over. in various places in the neighborhood the ichthyolites are found _in situ_ in their coffin-like nodules, where it is impossible to trace the relation of the beds in which they occur to the rocks above and below; and i had suspected for years that in at least some of the localities, they could not have belonged to the lower platform of death, but to some posterior catastrophe that had strewed with carcasses some upper platform. i had thought over the matter many a time and oft when i should have been asleep,--for it is marvellous how questions of the kind grow upon a man; and now, selecting as a hopeful scene of inquiry the splendid section under the northern sutor, i set myself doggedly to determine whether the old red sandstone in this part of the country has not at least its two storeys of organic remains, each of which had been equally a scene of sudden mortality. i was entirely successful. the lower ichthyolite bed occurs exactly one hundred and fourteen feet over the great conglomerate; and three hundred and eighteen feet higher up i found a second ichthyolite bed, as rich in fossils as the first, with its thorny acanthodians twisted half round, as if still in the agony of dissolution, and its pterichthyes still extending their spear-like arms in the attitude of defence. the discovery enabled me to assign to their true places the various ichthyolite beds of the district. those in the immediate neighborhood of the town, and a bed which abuts on the lias at eathie, belong to the upper platform; while those which appear in eathie burn, and along the shores at navity, belong to the lower. the chief interest of the discovery, however, arises from the light which it throws on the condition of the ancient ocean of the lower old red, and on the extreme precariousness of the tenure on which the existence of its numerous denizens was held. in a section of little more than a hundred yards there occur at least two platforms of violent death,--platforms inscribed with unequivocal evidence of two great catastrophes which over wide areas depopulated the seas. in the old red sandstone of caithness there are many such platforms: storey rises over storey; and the floor of each bears its closely-written record of disaster and sudden extinction. pompeii in this northern locality lies over herculaneum, and anglano over both. we cease to wonder why the higher order of animals should not have been introduced into a scene of being that had so recently arisen out of chaos, and over which the reign of death so frequently returned. in a somewhat different sense from that indicated by the poet of the "seasons," "as yet the trembling _year_ was unconfirmed, and _winter_ oft at eve resumed the gale." lying detached in the stratified clay of the fish-beds, there occur in abundance single plates and scales of ichthyolites, which, as they can be removed entire, and viewed on both sides, illustrate points in the mechanism of the creatures to which they belonged that cannot be so clearly traced in the same remains when locked up in stone. there is a vast deal of skilful carpentry exhibited--if carpentry i may term it--in the coverings of these ancient ichthyolites. in the commoner fish of our existing seas the scales are so thin and flexible,--mere films of horn,--that there is no particularly nice fitting required in their arrangement. the condition, too, through which portions of unprotected skin may be presented to the water, as over and between the rays of the fins, and on the snout and lips, obviates many a mechanical difficulty of the earlier period, when it was a condition, as the remains demonstrate, that no bit of naked skin, should be exposed, and when the scales and plates were formed, not of thin horny films, but of solid pieces of bone. thin slates lie on the roof of a modern dwelling, without any nice fitting;--they are scales of the modern construction: but it required much nice fitting to make thick flagstones lie on the roof of an ancient cathedral;--_they_, on the other hand, were scales of the ancient type. again, it requires no ingenuity whatever, to suffer the hands and face to go naked,--and such is the condition of our existing fish, with their soft skinny snouts and membranous fins; but to cover the hands with flexible steel gauntlets, and the face with such an iron mask as that worn by the mysterious prisoner of louis xiv., would require a very large amount of ingenuity indeed; and the ancient ichthyolites of the old red were all masked and gauntleted. now the detached plates and scales of the stratified clay exhibit not a few of the mechanical contrivances through which the bony coverings of these fish were made to unite--as in coats of old armor--great strength with great flexibility. the scales of the osteolepis and diplopterus i found nicely bevelled atop and at one of the sides; so that where they overlapped each other,--for at the joints not a needle-point could be insinuated,--the thickness of the two scales equalled but the thickness of one scale in the centre, and thus an equable covering was formed. i brought with me some of these detached scales, and they now lie fitted together on the table before me, like pieces of complicated hewn work carefully arranged on the ground ere the workman transfers them to their place on the wall. in the smaller-scaled fish, such as the cheiracanthus and cheirolepis, a different principle obtained. the minute glittering rhombs of bone were set thick on the skin, like those small scales of metal sewed on leather, that formed an inferior kind of armor still in use in eastern nations, and which was partially used in our own country just ere the buff coat altogether superseded the coat of mail. i found a beautiful piece of jaw in the clay, with the enamelled tusks bristling on its brightly enamelled edge, like iron teeth in an iron rake. mr. parkinson expresses some wonder, in his work on fossils, that in a fine ichthyolite in the british museum, not only the teeth should have been preserved, but also the lips; but we now know enough of the construction of the more ancient fish, to cease wondering. the lips were formed of as solid bone as the teeth themselves, and had as fair a chance of being preserved entire; just as the metallic rim of a toothed wheel has as fair a chance of being preserved as the metallic teeth that project from it. i was interested in marking the various modes of attachment to the body of the animal which the detached scales exhibit. the slater fastens on his slates with nails driven into the wood: the tiler secures his tiles by means of a raised bar on the under side of each, that locks into a corresponding bar of deal in the framework of the roof. now in some of the scales i found the art of the tiler anticipated; there were bars raised on their inner sides, to lay hold of the skin beneath; while in others it was the art of the slater that had been anticipated,--the scales had been slates fastened down by long nails driven in slantwise, which were, however, mere prolongations of the scale itself. great truths may be repeated until they become truisms, and we fail to note what they in reality convey. the great truth that all knowledge dwelt without beginning in the adorable creator must, i am afraid, have been thus common-placed in my mind; for at first it struck me as wonderful that the humble arts of the tiler and slater should have existed in perfection in the times of the old red sandstone. i had often remarked amid the fossiliferous limestones of the lower old red, minute specks and slender veins of a glossy bituminous substance somewhat resembling jet, sufficiently hard to admit of a tolerable polish, and which emitted in the fire a bright flame, i had remarked, further, its apparent identity with a substance used by the ancient inhabitants of the northern part of the country in the manufacture of their rude ornaments, as occasionally found in sepulchral urns, such as beads of an elliptical form, and flat parallelograms, perforated edge-wise by some four or five holes a-piece; but i had failed hitherto in detecting in the stone, portions of sufficient bulk for the formation of either the beads or the parallelograms. on this visit to the ichthyolite beds, however, i picked up a nodule that inclosed a mass of the jet large enough to admit of being fashioned into trinkets of as great bulk as any of the ancient ones i have yet seen, and a portion of which i succeeded in actually forming into a parallelogram, that could not have been distinguished from those of our old sepulchral urns. it is interesting enough to think, that these fossiliferous beds, altogether unknown to the people of the country for many centuries, and which, when i first discovered them, some twelve or fourteen years ago, were equally unknown to geologists, should have been resorted to for this substance, perhaps thousands of years ago, by the savage aborigines of the district. but our antiquities of the remoter class furnish us with several such facts. it is comparatively of late years that we have become acquainted with the yellow chalk-flints of banffshire and aberdeen; though before the introduction of iron into the country they seem to have been well known all over the north of scotland. i have never yet seen a stone arrow-head found in any of the northern localities, that had not been fashioned out of this hard and splintery substance,--a sufficient proof that our ancestors, ere they had formed their first acquaintance with the metals, were intimately acquainted with at least the mechanical properties of the chalk-flint, and knew where in scotland it was to be found. they were mineralogists enough, too, as their stone battle-axes testify, to know that the best tool-making rock is the axe-stone of werner; and in some localities they must have brought their supply of this rather rare mineral from great distances. a history of those arts of savage life, as shown in the relics of our earlier antiquities, which the course of discovery sereved thoroughly to supplant, but which could not have been carried on without a knowledge of substances and qualities afterwards lost, until re-discovered by scientific curiosity, would form of itself an exceedingly curious chapter. the art of the gun-flint maker (and it, too, promises soon to pass into extinction) is unquestionably a curious one, but not a whit more curious or more ingenious than the art possessed by the rude inhabitants of our country eighteen hundred years ago, of chipping arrow-heads with an astonishing degree of neatness out of the same stubborn material. they found, however, that though flint made a serviceable arrow-head, it was by much too brittle for an adze or battle-axe; and sought elsewhere than among the banffshire gravels for the rock out of which these were to be wrought. where they found it in our northern provinces i have not yet ascertained. it is but a short time since i came to know that they were beforehand with me in the discovery of the bituminous jet of the lower old red sandstone, and were excavators among its fossiliferous beds. the vitrified forts of the north of scotland give evidence of yet another of the obsolete arts. before the savage inhabitants of the country were ingenious enough to know the uses of mortar, or were furnished with tools sufficiently hard and solid to dress a bit of sandstone, they must have been acquainted with the _chemical_ fact, that with the assistance of fluxes, a pile of stones could be fused into a solid wall, and with the _mineralogical_ fact, that there are certain kinds of stones which yield much more readily to the heat than others. the art of making vitrified forts was the art of making ramparts of rock through a knowledge of the less obstinate earths and the more powerful fluxes. i have been informed by mr. patrick duff of elgin, that he found, in breaking open a vitrified fragment detached from an ancient hill-fort, distinct impressions of the serrated kelp-weed of our shores,--the identical flux which, in its character as the kelp of commerce, was so extensively used in our glass-houses only a few years ago. i was struck, during my explorations at this time, as i had been often before, by the style of grouping, if i may so speak, which obtains among the lower old red fossils. in no deposit with which i am acquainted, however rich in remains, have all its ichthyolites been found lying together. the collector finds some one or two species very numerous; some two or three considerably less so, but not unfrequent; some one or two more, perhaps, exceedingly rare; and a few, though abundant in other localities, that never occur at all. in the cromarty beds, for instance, i never found a holoptychius, and a dipterus only once; the diplopterus is rare; the glyptolepis not common; the cheirolepis and pterichthys more so, but not very abundant; the cheiracanthus and diplacanthus, on the other hand, are numerous; and the osteolepis and coccosteus more numerous still. but in other deposits of the same formation, though a similar style of grouping obtains, the proportions are reversed with regard to species and genera: the fish rare in one locality abound in another. in banniskirk, for instance, the dipterus is exceedingly common, while the osteolepis and coccosteus are rare, and the cheiracanthus and cheirolepis seem altogether awanting. again, in the morayshire deposits, the glyptolepis is abundant, and noble specimens of the lower old red holoptychius--of which more anon--are to be found in the neighborhood of thurso, associated with remains of the diplopterus, coccosteus, dipterus, and osteolepis. the fact may be deemed of some little interest by the geologist, and may serve to inculcate caution, by showing that it is not always safe to determine regarding the place or age of subordinate formations from the per centage of certain fossils which they may be found to contain, or from the fact that they should want some certain organisms of the system to which they belong, and possess others. these differences may and do exist in contemporary deposits; and i had a striking example, on this occasion, of their dependence on a simple law of instinct, which is as active in producing the same kind of phenomena now as it seems to have been in the earlier days of the old red sandstone. the cromarty and moray friths, mottled with fishing boats (for the bustle of the herring fishers had just begun), stretched out before me. a few hundred yards from the shore there was a yawl lying at anchor, with an old fisherman and a few boys angling from the stern for sillocks (the young of the coal-fish) and for small rock-cod. a few miles higher up, where the cromarty frith expands into a wide landlocked basin, with shallow sandy shores, there was a second yawl engaged in fishing for flounders and small skate,--for such are the kinds of fish that frequent the flat shallows of the basin. a turbot-net lay drying in the sun: it served to remind me that some six or eight miles away, in an opposite direction, there is a deep-sea bank, on which turbot, halibut, and large skate are found. numerous boats were stretching down the moray frith, bound for the banks of a more distant locality, frequented at this early stage of the herring fishing by shoals of herrings, with their attendant dog-fish and cod; and i knew that in yet another deep-sea range there lie haddock and whiting banks. almost every variety of existing fish in the two friths has its own peculiar habitat; and were they to be destroyed by some sudden catastrophe, and preserved by some geologic process, on the banks and shoals which they frequent, there would occur exactly the same phenomena of grouping in the fossiliferous contemporaneous deposits which they would thus constitute, as we find exhibited by the deposits of the lower old red sandstone. the remains of holoptychius occur, i have said, in the neighborhood of thurso. i must now add, that very singular remains they are,--full of interest to the naturalist, and, in great part at least, new to geology. my readers, votaries of the stony science, must be acquainted with the masterly paper of mr. sedgwick and sir r. murchison "on the old red sandstone of caithness and the north of scotland generally," which forms part of the second volume (second series) of the "transactions of the geological society," and with the description which it furnishes, among many others, of the rocks in the neighborhood of thurso. calcareo-bituminous flags, grits, and shales, of which the paving flagstones of caithness may be regarded as the general type, occur on the shores, in reefs, crags, and precipices; here stretching along the coast in the form of flat, uneven bulwarks: there rising over it in steep walls; yonder leaning to the surf, stratum against stratum, like flights of stairs thrown down from their slant position to the level; in some places severed by faults; in others cast about in every possible direction, as if broken and contorted by a thousand antagonist movements; but in their general bearing rising towards the east, until the whole calcareo-bituminous schists of which this important member of the system is composed disappear under the red sandstones of dunnet head. such, in effect, is the general description of mr. sedgwick and sir r. murchison, of the rocks in the neighborhood of thurso. it indicates further, that in at least three localities in the range there occur in the grits and shales, scales and impressions of fish. and such was the ascertained geology of the deposit when taken up last year by an ingenious tradesman of thurso, mr. robert dick, whose patient explorations, concentrated mainly on the fossil remains of this deposit, bid fair to add to our knowledge of the ichthyology of the old red sandstone. let us accompany mr. dick in one of his exploratory rambles. the various organisms which he disinterred i shall describe from specimens before me, which i owe to his kindness,--the localities in which he found them, from a minute and interesting description, for which i am indebted to his pen. leaving behind us the town at the bottom of its deep bay, we set out to explore a bluff-headed parallelogramical promontory, bounded by thurso bay on the one hand, and murkle bay on the other, and which presents to the open sea, in the space that stretches between, an undulating line of iron-bound coast, exposed to the roll of the northern ocean. we pass two stations in which the hard caithness flagstones so well known in commerce are jointed by saws wrought by machinery. as is common in the old red sandstone, in which scarce any stratum solid enough to be of value to the workmen, whether for building or paving, contains good specimens, we find but little to detain us in the dark coherent beds from which the flags are quarried. here and there a few glittering scales occur; here and there a few coprolitic patches; here and there the faint impression of a fucoid; but no organism sufficiently entire to be transferred to the bag. as we proceed outwards, however, and the fitful breeze comes laden with the keen freshness of the open sea, we find among the hard dark strata in the immediate neighborhood of thurso castle, a paler-colored bed of fine-grained semi-calcareous stone, charged with remains in a state of coherency and keeping better fitted to repay the labor of the specimen-collector. the inclosing matrix is comparatively soft: when employed in the neighboring fences as a building stone, we see it resolved by the skyey influences into well-nigh its original mud; whereas the organisms which it contains are composed of a hard, scarce destructible substance,--bone steeped in bitumen; and the enamel on their outer surfaces is still as glossy and bright as the japan on a _papier-maché_ tray fresh from the hands of the workman. their deep black, too, contrasts strongly with the pale hue of the stone. they consist chiefly of scales, spines, dermal plates, snouts, skull-caps, and vegetable impressions. a little farther on, in a thick bed interposed between two faults, the same kind of remains occur in the same abundance, largely mingled with scales and teeth of holoptychius, tuberculated plates, and coprolitic blotches; and further on still, in a rubbly flagstone, near where a little stream comes trotting merrily from the uplands to the sea, there occur skull-plates,--at least one of which has been disinterred entire,--large and massy as the helmets of ancient warriors. we have now reached the outer point of the promontory, where the seaward wave, as it comes rolling unbroken from the pole, crosses, in nearing the shore, the eastward sweep of the great gulf-stream, and then casts itself headlong on the rocks. the view has been extending with almost every step we have taken, and it has now expanded into a wide and noble prospect of ocean and bay, island and main, bold surf-skirted headlands, and green retiring hollows. yonder, on the one hand, are the orkneys, rising dim and blue over the foam-mottled currents of the pentland frith; and yonder, on the other, the far-stretching promontory of holborn head, with the line of coast that sweeps along the opposite side of the bay; here sinking in abrupt flagstone precipices direct into the tide; there receding in grassy banks formed of a dark blue diluvium. the fields and dwellings of living men mingle in the landscape with old episcopal ruins and ancient burying-grounds; and yonder, well-nigh in the opening of the frith, gleams ruddy to the sun,--a true blood-colored blush, when all around is azure or pale,--the tall red sandstone precipices of dunnet head. it has been suggested that the planet mars may owe its red color to the extensive development of some such formation as the old red sandstone of our own planet: the existing formation in mars may, at the present time, it is said, be a red sandstone formation. it seems much more probable, however, that the red flush which characterizes the whole of that planet,--its oceans as certainly as its continents,--should be rather owing to some widely-diffused peculiarity of the surrounding atmosphere, than to aught peculiar in the varied surface of land and water which that atmosphere surrounds; but certainly the extensive existence of such a red system might produce the effect. if the rocks and soils of dunnet head formed average specimens of those of our globe generally, we could look across the heavens at mars with a disk vastly more rubicund and fiery than his own. the earth, as seen from the moon, would seem such a planet bathed in blood as the moon at its rising frequently appears from the earth. we have rounded the promontory. the beds exposed along the coast to the lashings of the surf are of various texture and character,--here tough, bituminous, and dark; there of a pale hue, and so hard that they ring to the hammer like plates of cast iron; yonder soft, unctuous, and green,--a kind of chloritic sandstone. and these very various powers of resistance and degrees of hardness we find indicated by the rough irregularities of the surface. the softer parts retire in long trench-like hollows,--the harder stand out in sharp irregular ridges. fossils abound: the bituminous beds glitter bright with glossy quadrangular scales, that look like sheets of black mica inclosed in granite. we find jaws, teeth, tubercled plates, skull-caps, spines, and fucoids,--"tombs among which to contemplate," says mr. dick, "of which hervey never dreamed." the condition of complete keeping in which we discover some of these remains, even when exposed to the incessant dash of the surf, seems truly wonderful. we see scales of holoptychius standing up in bold relief from the hard cherty rock that has worn from around them, with all the tubercles and wavy ridges of their sculpture entire. this state of keeping seems to be wholly owing to the curious chemical change that has taken place in their substance. ere the skeleton of the bruce, disinterred entire after the lapse of five centuries, was recommitted to the tomb, there were such measures taken to secure its preservation, that were it to be again disinterred even after as many centuries more had passed, it might be found retaining unbroken its gigantic proportions. there was molten pitch poured over the bones in a state of sufficient fluidity to permeate all their pores, and fill up the central hollows, and which, soon hardening around them, formed a bituminous matrix, in which they may lie unchanged for more than a thousand years. now, exactly such was the process of keeping to which nature resorted with these skeletons of the old red sandstone. the animal matter with which they were charged had been converted into a hard black bitumen. like the bones of the bruce, they are bones steeped in pitch; and so thoroughly is every pore and hollow still occupied, that, when cast into the fire, they flamed like torches. in one of the beds at which we have now arrived mr. dick found the occipital plates of a holoptychius of gigantic proportions. the frontal plates measured full sixteen inches across, and from the nape of the neck to a little above the place of the eyes, full eighteen; while a single plate belonging to the lower part of the head measures thirteen and a half inches by seven and a half. i have remarked, in my little work on the old red sandstone,--founding on a large amount of negative evidence, that a mediocrity of size and bulk seems to have obtained among the fish of the lower old red, though in at least the upper formation, a considerable increase in both took place. a single piece of positive evidence, however, outweighs whole volumes of a merely negative kind. from the entire plate now in my possession, which is identical with one figured in mr. noble of st. madoes' specimen, and from the huge fragments of the upper plates now before me, some of which are full five-eighth parts of an inch in thickness, i am prepared to demonstrate that this holoptychius of the lower old red must have been at least thrice the size of the _holoptychius nobilissimus_ of clashbennie. still we pass on, though with no difficulty, over the rough contorted crags, worn by the surf into deep ruts and uneven ridges, gnarled protuberances, and crater-like hollows. the fossiliferous beds are still very numerous, and largely charged with remains. we see dermal bones, spines, scales, and jaws, projecting in high relief from the sea-worn surface of the ledges below, and from the weatherworn faces of the precipices above; for an uneven wall of crags some thirty or forty feet high, now runs along the shore. we have reached what seems a large mole, that sloping downwards athwart the beach from the precipices, like a huge boat-pier, runs far into the surf. we find it composed of a siliceous bed, so intensely compact and hard, that it has preserved its proportions entire, while every other rock has worn from around it. for century after century have the storms of the fierce north-west sent their long ocean-nursed waves to dash against it in foam; for century after century have the never-ceasing currents of the pentland chafed against its steep sides, or eddied over its rough crest; and yet still does it remain unwasted and unworn,--its abrupt wall retaining all its former steepness, and every angular jutting all the original sharpness of edge. as we advance the scenery becomes wilder and more broken: here an irregular wall of rock projects from the crags towards the sea; there a dock-like hollow, in which the water gleams green, intrudes from the sea upon the crags; we pass a deep lime-encrusted cave, with which tradition associates some wild legends, and which, from the supposed resemblance of the hanging stalactites to the entrails of a large animal wounded in the chase, bears the name of pudding-gno; and then, turning an angle of the coast, we enter a solitary bay, that presents at its upper extremity a flat expanse of sand. our walk is still over sepulchres charged with the remains of the long-departed. scales of holoptychius abound, scattered like coin over the surface of the ledges. it would seem--to borrow from mr. dick--as if some old lord of the treasury, who flourished in the days of the coal-money currency, had taken a squandering fit at sanday bay, and tossed the dingy contents of his treasure-chest by shovelfuls upon the rocks. mr. dick found in this locality some of his finest specimens, one of which--the inner side of the skull-cap of a holoptychius, with every plate occupying its proper place, and the large angular holes through which the eyes looked out still entire--i trust to be able by and by to present to the public in a good engraving. there occur jaws, plates, scales spines,--the remains of fucoids, too, of great size and in vast abundance. mr. dick has disinterred from among the rocks of sanday bay flattened carbonaceous stems four inches in diameter. we are still within an hour's walk of thurso; but in that brief hour how many marvels have we witnessed!--how vast an amount of the vital mechanisms of a perished creation have we not passed over! our walk has been along ranges of sepulchres, greatly more wonderful than those of thebes or petræa, and mayhap a thousand times more ancient. there is no lack of life along the shores of the solitary little bay. the shriek of the sparrow-hawk mingles from the cliffs with the hoarse deep croak of the raven; the cormorant on some wave-encircled ledge, hangs out his dark wing to the breeze; the spotted diver, plying his vocation on the shallows beyond, dives and then appears, and dives and appears again, and we see the silver glitter of scales from his beak; and far away in the offing the sunlight falls on a scull of seagulls, that flutter upwards, downwards, and athwart, now in the air, thick as midges over some forest-brook in an evening of midsummer. but we again pass onwards, amid a wild ruinous scene of abrupt faults, detached fragments of rocks, and reversed strata: again the ledges assume their ordinary position and aspect, and we rise from lower to higher and still higher beds in the formation,--for such, as i have already remarked, is the general arrangement from west to east, along the northern coast of caithness, of the old red sandstone. the great conglomerate base of the formation we find largely developed at port skerry, just where the western boundary line of the county divides it from the county of sutherland; its thick upper coping of sandstone we see forming the tall cliffs of dunnet head; and the greater part of the space between, nearly twenty miles as the crow flies, is occupied chiefly by the shales, grits, and flagstones, which we have found charged so abundantly with the strangely-organized ichthyolites of the second stage of vertebrate existence. in the twenty intervening miles there are many breaks and faults, and so there may be, of course, recurrences of the same strata, and re-appearances of the same beds; but, after making large allowance for partial foldings and repetitions, we must regard the development of this formation, with which the twenty miles are occupied, as truly enormous. and yet it is but one of three that occur in a single system. we reach the long flat bay of dunnet, and cross its waste of sands. the incoherent coils of the sand-worm lie thick on the surface; and here a swarm of buzzing flies, disturbed by the foot, rises in a cloud from some tuft of tangled sea-weed; and here myriads of gray crustaceous sand-hoppers dart sidelong in the little pools, or vault from the drier ridges a few inches into the air. were the trilobites of the silurian system,--at one period, as their remains testify, more than equally abundant,--creatures of similar habits? we have at length arrived at the tall sandstone precipices of dunnet, with their broad decaying fronts of red and yellow; but in vain may we ply hammer and chisel among them: not a scale, not a plate, not even the stain of an imperfect fucoid appears. we have reached the upper boundary of the lower old red formation, and find it bordered by a desert devoid of all trace of life. some of the characteristic types of the formation re-appear in the upper deposits; but though there is a reproduction of the original works in their more characteristic passages, if i may so speak, many of the readings are diverse, and the editions are all new. it is one of the circumstances of peculiar interest with which geology at its present stage is invested, that there is no man of energy and observation who may not rationally indulge in the hope of extending its limits by adding to its facts. mr. dick, an intelligent tradesman of thurso, agreeably occupies his hours of leisure, for a few months, in detaching from the rocks in his neighborhood their organic remains; and thus succeeds in adding to the existing knowledge of palæozoic life, by disinterring ichthyolites which even agassiz himself would delight to figure and describe. several of the specimens in my possession, which i owe to the kindness of mr. dick, are so decidedly unique, that they would be regarded as strangers in the completest geological museums extant. it is a not uncurious fact, that when the thurso tradesman was pursuing his labors of exploration among rocks beside the pentland frith, a man of similar character was pursuing exactly similar labors, with nearly similar results, among rocks of nearly the same era, that bound, on the coast of cornwall, the british channel. when the one was hammering in "ready-money cove," the other, at the opposite end of the island, was disturbing the echoes of "pudding-gno;" and scales, plates, spines, and occipital fragments of palæozoic fishes rewarded the labors of both. in an article on the scientific meeting at york, which appeared in "chambers' journal" in the november of last year, the reading public were introduced to a singularly meritorious naturalist, mr. charles peach,[ ] a private in the mounted guard (preventive service), stationed on the southern coast of cornwall, who has made several interesting discoveries on the outer confines of the animal kingdom, that have added considerably to the list of our british zoöphites and echinodermata. the article, a finely-toned one, redolent of that pleasing sympathy which mr. robert chambers has ever evinced with struggling merit, referred chiefly to mr. peach's labors as a naturalist; but he is also well known in the geological field. chapter xii. ichthyolite beds of clune and lethenbarn--limestone quarry--destruction of urns and sarcophagi in the lime-kiln--nodules opened--beautiful coloring of the remains--patrick duff's description--new genus of morayshire ichthyolite described--form and size of the nodules or stone coffins--illustration from mrs. marshall's cements--forest of darnaway--the hill of berries--sluie--elgin--outliers of the weald and the oölite--description of the weald at linksfield--mr. duff's _lepidotus minor_--eccentric types of fish scales--visit to the sandstones of scat-craig--fine suit of fossils at scat-craig--true graveyard bones, not mere impressions--varieties of pattern--the diker's "carved flowers"--_stagonolepis_, a new genus--termination of the ramble. my term of furlough was fast drawing to a close. it was now wednesday the th august, and on monday the th it behooved me to be seated at my desk in edinburgh. i took boat, and crossed the moray frith from cromarty to nairn, and then walked on, in a very hot sun, over shakspeare's moor to boghole, with the intention of examining the ichthyolite beds of clune and lethenbarn, and afterwards striking across the country to forres, through the forest of darnaway, where the forest abuts on the findhorn, at the picturesque village of sluie. when i had last crossed the moor, exactly ten years before, it was in a tremendous storm of rain and wind; and the dark platform of heath and bog, with its old ruinous castle standing sentry over it, seemed greatly more worthy of the genius of the dramatist, as cloud after cloud dashed over it, like ocean waves breaking on some low volcanic island, than it did on this clear, breathless afternoon, in the unclouded sunshine. but the sublimity of the moor on which macbeth met the witches depends in no degree on that of the "heath near forres," whether seen in foul weather or fair; its topography bears relation to but the mind of shakspeare; and neither tile-draining nor the plough will ever lessen an inch of its area. the limestone quarry of clune has been opened on the edge of an extensive moor, about three miles from the public road, where the province of moray sweeps upwards from the broad fertile belt of corn-land that borders on the sea, to the brown and shaggy interior. there is an old-fashioned bare-looking farm-house on the one side, surrounded by a few uninclosed patches of corn; and the moorland, here dark with heath, there gray with lichens, stretches away on the other. the quarry itself is merely a piece of moor that has been trenched to the depth of some five or six feet from the surface, and that presents, at the line where the broken ground leans against the ground still unbroken, a low uneven frontage, somewhat resembling that of a ruinous stone-fence. it has been opened in the outcrop of an ichthyolite bed of the lower old red sandstone, on which in this locality the thin moory soil immediately rests, without the intervention of the common boulder clay of the country; and the fish-enveloping nodules, which are composed in this bed of a rich limestone, have been burnt, for a considerable number of years, for the purposes of the agriculturist and builder. there was a kiln smoking this evening beside the quarry; and a few laborers were engaged with shovel and pickaxe in cutting into the stratified clay of the unbroken ground, and throwing up its spindle-shaped nodules on the bank, as materials for their next burning. antiquaries have often regretted that the sculptured marble of greece and egypt,--classic urns, to whose keeping the ashes of the dead had been consigned, and antique sarcophagi, roughened with hieroglyphics,--should have been so often condemned to the lime-kiln by the illiterate copt or tasteless mohammedan; and i could not help experiencing a somewhat similar feeling here. the urns and sarcophagi, many times more ancient than those of greece and egypt, and that told still more wondrous stories, lay thickly ranged in this strange catacomb,--so thickly, that there were quite enough for the lime-kiln and the geologists too; but i found the kiln got all, and this at a time when the collector finds scarce any fossils more difficult to procure than those of the lower old red sandstone. i asked one of the laborers whether he did not preserve some of the better specimens, in the hope of finding an occasional purchaser. not now, he said: he used to preserve them in the days of lady cumming of altyre; but since her ladyship's death, no one in the neighborhood seemed to care for them, and strangers rarely came the way. the first nodule i laid open contained a tolerably well-preserved cheiracanthus; the second, an indifferent specimen of glyptolepis; and three others, in succession, remains of coccosteus. almost every nodule of one especial layer near the top incloses its organism. the coloring is frequently of great beauty. in the cromarty, as in the caithness, orkney, and gamrie specimens, the animal matter with which the bones were originally charged has been converted into a dark glossy bitumen, and the plates and scales glitter from a ground of opaque gray, like pieces of japan-work suspended against a rough-cast wall. but here, as in the other morayshire deposits, the plates and scales exist in nearly their original condition, as bone that retains its white color in the centre of the specimens, where its bulk is greatest, and is often beautifully tinged at its thinner edges by the iron with which the stone is impregnated. it is not rare to find some of the better preserved fossils colored in a style that reminds one of the more gaudy fishes of the tropics. we see the body of the ichthyolite, with its finely arranged scales, of a pure snow-white. along the edges, where the original substance of the bone, combining with the oxide of the matrix, has formed a phosphate of iron, there runs a delicately shaded band of plum-blue; while the out-spread fins, charged still more largely with the oxide, are of a deep red. the description of mr. patrick duff, in his "geology of moray," so redolent of the quiet enthusiasm of the true fossil-hunter, especially applies to the ichthyolites of this quarry, and to those of a neighboring opening in the same bed,--the quarry of lethenbarn. "the nodules," says mr. duff, "which in their external shape resemble the stones used in the game of curling, but are elliptical bodies instead of round, lie in the shale on their flat sides, in a line with the dip. when taken out, they remind one of water-worn pebbles, or rather boulders of a shore. a smart blow on the edge splits them along on the major axis, and exposes the interesting inclosure. the practised geologist knows well the thrilling interest attending the breaking up of the nodule: the uninitiated cannot sympathize with it. there is no time when a fossil looks so well as when first exposed. there is a clammy moisture on the surface of the scales or plates, which brings out the beautiful coloring, and adds brilliancy to the enamel. exposure to the weather soon dims the lustre; and even in a cabinet an old specimen is easily known by its tarnished aspect." i found at clune no ichthyolite to which the geologists have not been already introduced, or with which i had not been acquainted previously in the cromarty beds. the lower old red of morayshire furnishes, however, at least one genus not yet figured nor described, and of which, so far as i am aware, only a single specimen has yet been found. it seems to have been a small delicately-formed fish; its head covered with plates; its body with round scales of a size intermediate between those of the osteolepis and cheiracanthus; its anterior dorsal fin placed, as in the dipterus, diplopterus, and glyptolepis, directly opposite to its ventral fins; the enamelled surfaces of the minute scales were fretted with microscopic undulating ridges, that radiated from the centre to the circumference; similar furrows traversed the occipital plates; and the fins, unfurnished with spines, were formed, as in the dipterus and diplopterus, of thick-set, enamelled rays. the posterior fins and tail of the creature were not preserved. i may mention, for the satisfaction of the geologist, that i saw this unique fossil in the possession of the late lady cumming of altyre, a few weeks previous to the lamented death of her ladyship; and that, on assuring her it was as new in relation to the cromarty and caithness fish-beds as to those of moray, she intimated an intention of forthwith sending a drawing of it to agassiz; but her untimely decease in all probability interfered with the design, and i have not since heard of this new genus of ichthyolite, or of her ladyship's interesting specimen, hitherto apparently its only representative and memorial. in the morayshire, as in the cromarty beds, the limestone nodules take very generally the form of the fish which they inclose: they are stone coffins, carefully moulded to express the outline of the corpses within. is the fish entire?--the nodule is of a spindle form, broader at the head and narrower at the tail. is it slightly curved, in the attitude of violent death?--the nodule has also its slight curve. is it bent round, so that the extremities of the creature meet?--the nodule, in conformity with the outline, is circular. is it disjointed and broken?--the nodule is correspondingly irregular. in nine cases out of ten, the inclosing coffin, like that of an old mummy, conforms to the outline of the organism which it incloses. it is further worthy of remark, too, that a large fish forms generally a large nodule, and a small fish a small one. here, for instance, is a nodule fifteen inches in length, here a nodule of only three inches, and here a nodule of intermediate size, that measures eight inches. we find that the large nodule contains a cheirolepis thirteen inches in length, the small one a diplacanthus of but two and a half inches in length, and the intermediate one a cheiracanthus of seven inches. the size of the fish evidently regulated that of the nodule. the coffin is generally as good a fit in size as in form; and the bulk of the nodule bears almost always a definite proportion to the amount of animal matter round which it had formed. i was a good deal struck, a few weeks ago, in glancing over a series of experiments conducted for a different purpose by a lady of singular ingenuity,--mrs. marshall, the inventor and patentee of the beautiful marble-looking plaster, _intonacco_,--to find what seemed a similar principle illustrated in the compositions of her various cements. these are all formed of a basis of lime, mixed in certain proportions with organic matter. the reader must be familiar with cements of this kind long known among the people, and much used in the repairing of broken pottery, such as a cement compounded of quicklime made of oyster shells, mixed up with a glue made of skim-milk cheese, and another cement made also of quicklime mixed up with the whites of eggs. in mrs. marshall's cements, the organic matter is variously compounded of both animal and vegetable substances, while the earth generally employed is sulphate of lime; and the result is a close-grained marble-like composition, considerably harder than the sulphate in its original crystalline state. she had deposited, in one set of her experiments, the calcareous earth, mixed up with sand, clay, and other extraneous matters, on some of the commoner molluscs of our shores; and universally found that the mass, incoherent everywhere else, had acquired solidity wherever it had been permeated by the animal matter of the molluscs. each animal, in proportion to its size, is found to retain, as in the fossiliferous spindles of the old red sandstone, its coherent nodule around it. one point in the natural phenomenon, however, still remains unillustrated by the experiments of mrs. marshall. we see in them the animal matter giving solidity to the lime in immediate contact with it; but we do not see it possessing any such affinity for it as to form, in an argillaceous compound, like that of the ichthyolite beds, a centre of attraction powerful enough to draw together the lime diffused throughout the mass. it still remains for the geologic chemist to discover on what principle masses of animal matter should form the attracting nuclei of limestone nodules. the declining sun warned me that i had lingered rather longer than was prudent among the ichthyolites of clune; and so, striking in an eastern direction across a flat moor, through which i found the schistose gneiss of the district protruding in masses resembling half-buried boulders, i entered the forest of darnaway. there was no path, and much underwood, and i enjoyed the luxury of steering my course, out of sight of road and landmark, by the sun, and of being not sure at times whether i had skill enough to play the part of the bush-ranger under his guidance. a sultry day had clarified and cooled down into a clear, balmy evening; the slant beam was falling red on a thousand tall trunks,--here gleaming along some bosky vista, to which the white silky wood-moths, fluttering by scores, and the midge and the mosquito dancing by myriads, imparted a motty gold-dust atmosphere; there penetrating in straggling rays far into some gloomy recess, and resting in patches of flame, amid the darkness, on gnarled stem, or moss-cushioned stump, or gray beard-like lichen. i dislodged, in passing through the underwood, many a tiny tenant of the forest, that had a better right to harbor among its wild raspberries and junipers than i had to disturb them,--velvety night-moths, that had sat with folded wings under the leaves, awaiting the twilight, and that now took short blind flights of some two or three yards, to get out of my way,--and robust, well-conditioned spiders, whose elastic, well-tightened lines snapped sharp before me as i pressed through, and then curled up on the scarce perceptible breeze, like broken strands of wool. but every man, however whiggish in his inclinations, entertains a secret respect for the powerful; and though i passed within a few feet of a large wasps' nest, suspended to a jutting bough of furze, the wasps i took especial care _not_ to disturb. i pressed on, first through a broad belt of the forest, occupied mainly by melancholy scotch firs; next through an opening, in which i found an american-looking village of mingled cottages, gardens, fields and wood; and then through another broad forest-belt, in which the ground is more varied with height and hollow than in the first, and in which i found only forest trees, mostly oaks and beeches. i heard the roar of the findhorn before me, and premised i was soon to reach the river; but whether i should pursue it upwards or downwards, in order to find the ferry at sluie, was more than i knew. there lay in my track a beautiful hillock, that reclines on the one side to the setting sun, and sinks sheer on the other, in a mural sandstone precipice, into the findhorn. the trees open over it, giving full access to the free air and the sunshine; and i found it as thickly studded over with berries as if it had been the special care of half a dozen gardeners. the red light fell yet redder on the thickly inlaid cranberries and stone-brambles of the slope, and here and there, though so late in the season, on a patch of wild strawberries; while over all, dark, delicate blueberries, with their flour-bedusted coats, were studded as profusely as if they had been peppered over it by a hailstone cloud. i have seldom seen such a school-boy's paradise, and i was just thinking what a rare discovery i would have deemed it had i made it thirty years sooner, when i heard a whooping in the wood, and four little girls, the eldest scarcely eleven, came bounding up to the hillock, their lips and fingers already dyed purple, and dropped themselves down among the berries with a shout. they were sadly startled to find they had got a companion in so solitary a recess; but i succeeded in convincing them that they were in no manner of danger from him; and on asking whether there was any of them skilful enough to show me the way to sluie, they told me they all lived there, and were on their way home from school, which they attended at the village in the forest. hours had elapsed since the master had _let them go_, but in so fine an evening the berries wouldn't, and so they were still in the wood. i accompanied them to sluie, and was ferried over the river in a salmon coble. there is no point where the findhorn, celebrated among our scotch streams for the beauty of its scenery, is so generally interesting as in the neighborhood of this village; forest and river,--each a paragon in its kind,--uniting for several miles together what is most choice and characteristic in the peculiar features of both. in no locality is the surface of the great forest of darnaway more undulated, or its trees nobler; and nowhere does the river present a livelier succession of eddying pools and rippling shallows, or fret itself in sweeping on its zig-zag course, now to the one bank, now to the other, against a more picturesque and imposing series of cliffs. but to the geologist the locality possesses an interest peculiar to itself. the precipices on both sides are charged with fossils of the upper old red sandstone: they form part of a vast indurated graveyard, excavated to the depth of an hundred feet by the ceaseless wear of the stream; and when the waters are low, the teeth-plates and scales of ichthyolites, all of them specifically different from those of clune and lethenbarn, and most of them generically so, may be disinterred from the strata in handfuls. but the closing evening left me neither light nor time for the work of exploration. i heard the curfew in the woods from the yet distant town, and dark night had set in long ere i reached forres. on the following morning i took a seat in one of the south coaches, and got on to elgin an hour before noon. elgin, one of the finest of our northern towns, occupies the centre of a richly fossiliferous district, which wants only better sections to rank it among the most interesting in the kingdom. an undulating platform of old red sandstone, in which we see, largely developed in one locality, the lower formation of the coccosteus, and in another, still more largely, the upper formation of the _holoptychius nobilissimus_, forms, if i may so speak, the foundation deposit of the district,--the true geologic plane of the country; and, thickly scattered over this plane, we find numerous detached knolls and patches of the weald and the oölite, deposited like heaps of travelled soil, or of lime shot down by the agriculturist on the surface of a field. the old red platform is mottled by the outliers of a comparatively modern time: the sepulchral mounds of later races, that lived and died during the reptile age of the world, repose on the surface of an ancient burying-ground, charged with remains of the long anterior age of the fish; and over all, as a general covering, rest the red boulder-clay and the vegetable mould. mr. duff, in his valuable "sketch of the geology of moray," enumerates five several localities in the neighborhood of elgin in which there occur outliers of the weald; though, of course, in a country so flat, and in which the diluvium lies deep, we cannot hold that all have been discovered. and though the outliers of the oölite have not yet been ascertained to be equally numerous, they seem of greater extent; the isolated masses detached from them by the denuding agencies lie thick over extensive areas; and in working out the course of improvement which has already rendered elginshire the garden of the north, the ditcher at one time touches on some bed of shale charged with the characteristic ammonites and belemnites of the system, and at another on some calcareous sandstone bed, abounding with its pectens, its plagiostoma, and its pinnæ. some of these outliers, whether wealden or oölitic, are externally of great beauty. they occur in the parish of lhanbryde, about three miles to the east of elgin, in the form of green pyramidal hillocks, mottled with trees, and at linksfield, as a confluent group of swelling grassy mounds. and from their insulated character, and the abundance of organisms which they inclose, they serve to remind one of those green pyramids of central america in which the traveller finds deposited the skeleton remains of extinct races. it has been suggested by mr. duff, in his "sketch,"--a suggestion which the late sutherlandshire discoveries of mr. robertson of inverugie have tended to confirm,--that the oölite and weald of moray do not, in all probability, represent consecutive formations: they seem to bear the same sort of relation to each other as that mutually borne by the mountain limestone and the coal measures. the one, of lacustrine or of estuary origin, exhibits chiefly the productions of the land and its fresh waters; the other, as decidedly of marine origin, is charged with the remains of animals whose proper home was the sea. but the productions, though dissimilar, were in all probability contemporary, just as the crabs and periwinkles of the frith of forth are contemporary with the frogs and lymnea of flanders moss. i had little time for exploration in the neighborhood of elgin; but that little, through the kindness of my friend mr. duff, i was enabled to economize. we first visited together the outlier of the weald at linksfield. it may be found rising in the landscape, a short mile below the town, in the form of a green undulating hillock, half cut through by a limestone quarry; and the section thus furnished is of great beauty. the basis on which the hillock rests is formed of the well-marked calcareous band in the upper old red, known as the cornstone, which we find occurring here, as elsewhere, as a pale concretionary limestone of considerable richness, though in some patches largely mixed with a green argillaceous earth, and in others passing into a siliceous chert. over the pale-colored base, the section of the hillock is ribbed like an onyx: for about forty feet, bands of gray, green, and blue clays alternate with bands of cream-colored, light-green, and dark-blue limestones; and over all there rests a band of the red boulder-clay, capped by a thin layer of vegetable mould. it is a curious circumstance, well fitted to impress on the geologist the necessity of cautious induction, that the boulder-clay not only _overlies_, but also _underlies_, this fresh-water deposit; a bed of unequivocally the same origin and character with that at the top lying intercalated, as if filling up two low flat vaults, between the upper surface of the cornstone and the lower band of the weald. it would, however, be as unsafe to infer that this intervening bed is older than the overlying ones, as to infer that the rubbish which chokes up the vaulted dungeon of an old castle is more ancient than the arch that stretches over it. however introduced into the cavity which it occupies,--whether by land-springs or otherwise,--we find it containing fragments of the green and pale limestones that lie above, just as the rubbish of the castle dungeon might be found to contain fragments of the castle itself. when the bed of red boulder-clay was intercalated, the rocks of the overlying wealden were exactly the same sort of indurated substances that they are now, and were yielding to the operations of some denuding agent. the alternating clays and limestones of this outlier, each of which must have been in turn an upper layer at the bottom of some lake or estuary, are abundantly fossiliferous. in some the fresh-water character of the deposit is well marked: cyprides are so exceedingly numerous in some of the bands, that they impart to the stone an oölitic appearance; while others of a dark-colored limestone we see strewed over, like the oozy bottom of a modern lake, with specimens of what seem paludina, cyclas, and planorbus. some of the other shells are more equivocal: a mytilus or modiola, which abounds in some of the bands, may have been either a sea or a fresh-water shell; and a small oyster and astarte seem decidedly marine. remains of fish are very abundant,--scales, plates, teeth, ichthyodorulites, and in some instances entire ichthyolites. i saw, in the collection of mr. duff, a small but very entire specimen of _lepidotus minor_, with the fins spread out on the limestone, as in an anatomical preparation, and almost every plate and scale in its place. some of his specimens of ichthyodorulites, too, are exceedingly beautiful, and of great size, resembling jaws thickly set with teeth, the apparent teeth being mere knobs ranged along the concave edge of the bone, the surface of which we see gracefully fluted and enamelled. what most struck me, however, in glancing over the drawers of mr. duff, was the character of the ganoid scales of this deposit. the ganoid order in the days of the weald was growing old; and two new orders,--the ctenoid and cycloid,--were on the eve of taking its place in creation. hitherto it had comprised at least two-thirds of all the fish that had existed ever since the period in which fish first began; and almost every ganoid fish had its own peculiar pattern of scale. but it would now seem as if well nigh all the simpler patterns were exhausted, and as if, in order to give the variety which nature loves, forms of the most eccentric types had to be resorted to. with scarce any exception save that furnished by the scales of the _lepidotus minor_, which are plain lozenge-shaped plates, thickly japanned, the forms are strangely complex and irregular, easily expressible by the pencil, but beyond the reach of the pen. the remains of reptiles have been found occasionally, though rarely, in this outlier of the weald,--the vertebra of a plesiosaurus, the femur of some chelonian reptile, and a large fluted tooth, supposed saurian. i would fain have visited some of the neighboring outliers of the oölite, but time did not permit. mr. duff's collection, however, enabled me to form a tolerably adequate estimate of their organic contents. viewed in the group, these present nearly the same aspect as the organisms of the upper lias of pabba. there is in the same abundance large pinnæ, and well-relieved pectens, both ribbed and smooth; the same abundance, too, of belemnites and ammonites of resembling type. both the moray outliers and the pabba deposit have their terebratulæ, gervilliæ, plagiostoma, cardiadæ, their bright ganoid scales, and their imperfectly-preserved lignites. they belong apparently to nearly the same period, and must have been formed in nearly similar circumstances,--the one on the western, the other on the eastern coast of a country then covered by the vegetation of the oölite, and now known, with reference to an antiquity of but yesterday, as the ancient kingdom of scotland. i saw among the ammonites of these outliers at least one species, which, i believe, has not yet been found elsewhere, and which has been named, after mr. robertson of inverugie, the gentleman who first discovered it, _ammonites robertsoni_. like most of the genus to which it belongs, it is an exceedingly beautiful shell, with all its whorls free and gracefully ribbed, and bearing on its back, as its distinguishing specific peculiarity, a triple keel. i spent the evening of this day in visiting, with mr. duff, the upper old red sandstones of scat-craig. in elginshire, as in fife and elsewhere, the upper old red consists of three grand divisions,--a superior bed of pale yellow sandstone, which furnishes the finest building-stone anywhere found in the north of scotland,--an intermediate calcareous bed, known technically as the cornstone,--and an inferior bed of sandstone, chiefly, in this locality, of a grayish-red color, and generally very incoherent in its structure. the three beds, as shown by the fossil contents of the yellow sandstones above, and of the grayish-red sandstones below, are members of the same formation,--a formation which, in scotland at least, does not possess an organism in common with the middle old red formation; that of the cephalaspis, as developed in forfarshire, stirling, and ayr, or the lower old red formation; that of the coccosteus, as developed in caithness, cromarty, inverness, and banff shires, and in so many different localities in moray. the sandstones at scat-craig belong to the grayish-red base of the upper old red formation. they lie about five miles south of elgin, not far distant from where the palæozoic deposits of the coast-side lean against the great primary nucleus of the interior. we pass from the town, through deep rich fields, carefully cultivated and well inclosed: the country, as we advance on the moorlands, becomes more open; the homely cottage takes the place of the neat villa; the brown heath, of the grassy lea; and unfenced patches of corn here and there alternate with plantings of dark sombre firs, in their mediocre youth. at length we near the southern boundary of the landscape,--an undulating moory ridge, partially planted; and see where a deep gap in the outline opens a way to the upland districts of the province, a lively hill-stream descending towards the east through the bed which it has scooped out for itself in a soft red conglomerate. the section we have come to explore lies along its course: it has been the grand excavator in the densely occupied burial-ground over which it flows; but its labors have produced but a shallow scratch after all,--a mere ditch, some ten or twelve feet deep, in a deposit the entire depth of which is supposed greatly to exceed a hundred fathoms. the shallow section, however, has been well wrought; and its suit of fossils is one of the finest, both from the great specific variety which they exhibit, and their excellent state of keeping, that the upper old red sandstone has anywhere furnished. so great is the incoherency of the matrix, that we can dig into it with our chisels, unassisted by the hammer. it reminds us of the loose gravelly soil of an ancient graveyard, partially consolidated by a night's frost,--a resemblance still further borne out by the condition and appearance of its organic contents. the numerous bones disseminated throughout the mass do not exist, as in so many of the upper old red sandstone rocks, as mere films or impressions, but in their original forms, retaining bulk as well as surface: they are true graveyard bones, which may be detached entire from the inclosing mass, and of which, were we sufficiently well acquainted with the anatomy of the long-perished races to which they belonged, entire skeletons might be reconstructed. i succeeded in disinterring, during my short stay, an occipital plate of great beauty, fretted on its outer surface by numerous tubercles, confluent on its anterior part, and surrounded on its posterior portion, where they stand detached, by punctulated markings. i found also a fine scale of _holoptychius nobilissimus_, and a small tooth, bent somewhat like a nail that had been drawn out of its place by two opposite wrenches, and from the internal structure of which professor owen has bestowed on the animal to which it belonged the generic name dendrodus. i have ascertained, however, through the indispensable assistance of mr. george sanderson, that the genus holoptychius of agassiz, named from a peculiarity in the sculpture of the scale, is the identical genus dendrodus of professor owen, named from a peculiarity in the structure of the teeth. those teeth of the genus holoptychius, whether of the lower or upper old red, that belong to the second or _reptile_ row with which the creature's jaws were furnished, present in the cross section the appearance of numerous branches, like those of trees, radiating from a centre like spokes from the nave of a wheel; and their arborescent aspect suggested to the professor the name dendrodus. it seems truly wonderful, when one but considers it, to what minute and obscure ramifications the variety of pattern, specific and generic, which nature so loves to preserve, is found to descend. we see great diversity of mode and style in the architecture of a city built of brick; but while the houses are different, the bricks are always the same. it is not so in nature. the bricks are as dissimilar as the houses. we find, for instance, those differences, specific and generic, that obtain among fishes, both recent and extinct, descending to even the microscopic structure of their teeth. there is more variety of pattern,--in most cases of very elegant pattern,--in the sliced fragments of the teeth of the ichthyolites of a single formation, than in the carved blocks of an extensive calico-print yard. each species has its own distinct pattern, as if in all the individuals of which it consisted the same block had been employed to stamp it; each genus has its own general _type_ of pattern, as if the same inventive idea, variously altered and modified, had been wrought upon in all. in the genus dendrodus, for instance, it is the generic type, that from a central nave there should radiate, spoke-like, a number of leafy branches; but in the several species, the branches, if i may so express myself, belong to different shrubs, and present dissimilar outlines. there are no repetitions of earlier patterns to be found among the generically different ichthyolites of other formations. we see in the world of fashion old modes of ornament continually reviving: the range of invention seems limited; and we find it revolving, in consequence, in an irregular, ever-returning cycle. but infinite resource did not need to travel in a circle, and so we find no return or doublings in its course. it has appeared to me, that an argument against the transmutation of species, were any such needed, might be founded on those inherent peculiarities of structure that are ascertained thus to pervade the entire texture of the framework of animals. if we find one building differing from another merely in external form, we have no difficulty in conceiving how, by additions and alterations, they might be made to present a uniform appearance; transmutation, development, progression,--if one may use such terms,--seem possible in such circumstances. but if the buildings differ from each other, not only in external form, but also in every brick and beam, bolt and nail, no mere scheme of external alteration can induce a real resemblance. every brick must be taken down, and every beam and belt removed. the problem cannot be wrought by the remodelling of an old house: there is no other mode of solving it save by the erection of a new one. among the singularly interesting old red fossils of mr. duff's collection i saw the impression of a large ichthyolite from the superior yellow sandstone of the upper old red, which had been brought him by a country diker only a few days before. in breaking open a building stone, the diker had found the inside of it, he said, covered over with curiously carved flowers; and, knowing that mr. duff had a turn for curiosities, he had brought the flowers to him. the supposed flowers are the sculpturings on the scales of the ichthyolite; and, true to the analogy of the diker, on at least a first glance, they may be held to resemble the rather equivocal florets of a cheap wall-paper, or of an ornamental tile. the specimen exhibits the impressions of four rows of oblong rectangular scales. one row contains seven of these, and another eight. each scale averages about an inch and a quarter in length, by about three quarters of an inch in breadth; and the parallelogramical field which it presents is occupied by a curious piece of carving. by a sort of pictorial illusion, the device appears as if in motion: it would seem as if a sudden explosion had taken place in the middle of the field, and as if the numerous dislodged fragments, propelled all around by the central force, were hurrying to the sides. but these seeming fragments were not elevations in the original scale, but depressions. they almost seem as if they had been indented into it, in the way one sees the first heavy drops of a thunder shower indented into a platform of damp sea sand; and this last peculiarity of appearance seems to have suggested the name which this sole representative of an extinct genus has received during the course of the last few weeks from agassiz. an elgin gentleman forwarded to neufchatel a singularly fine calotype of the fossil, taken by mr. adamson of edinburgh, with a full-size drawing of a few of the scales; and from the calotype and the drawing the naturalist has decided that the genus is entirely new, and that henceforth it shall bear the descriptive name of stagonolepis, or drop-scale. as i looked for the first time on this broken fragment of an ichthyolite,--the sole representative and record of an entire genus of creatures that had been once called into existence to fulfil some wise purpose of the creator long since accomplished,--i bethought me of rogers's noble lines on the torso,-- "and dost thou still, thou mass of breathing stone, (thy giant limbs to night and chaos hurled) still sit as on the fragment of a world, surviving all?" here, however, was a still more wonderful torso than that of the dismembered hercules, which so awakened the enthusiasm of the poet. strange peculiarities of being,--singular habits, curious instincts, the history of a race from the period when the all-producing word had spoken the first individuals into being, until, in circumstances unfitted for their longer existence, or in some great annihilating catastrophe, the last individuals perished,--were all associated with this piece of sculptured stone; but, like some ancient inscription of the desert, written in an unknown character and dead tongue, its dark meanings were fast locked up, and no inhabitant of earth possessed the key. does that key anywhere exist, save in the keeping of him who knows all and produced all, and to whom there is neither past nor future? or is there a record of creation kept by those higher intelligences,--the first-born of spiritual natures,--whose existence stretches far into the eternity that has gone by, and who possess, as their inheritance, the whole of the eternity to come? we may be at least assured, that nothing can be too low for angels to remember, that was not too low for god to create. i took coach for edinburgh on the following morning; for with my visit to scat-craig terminated the explorations of my summer ramble. during the summer of the present year i have found time to follow up some of the discoveries of the last. in the course of a hasty visit to the island of eigg, i succeeded in finding _in situ_ reptile remains of the kind which i had found along the shores in the previous season, in detached water-rolled masses. the deposit in which they occur lies deep in the oölite. in some parts of the island there rest over it alternations of beds of trap and sedimentary strata, to the height of more than a thousand feet; but in the line of coast which intervenes between the farm-house of keill and the picturesque shieling described in my fifth chapter, it has been laid bare by the sea immediately under the cliffs, and we may see it jutting out at a low angle from among the shingle and rolled stones of the beach for several hundred feet together, charged everywhere with the teeth, plates, and scales of ganoid fishes, and somewhat more sparingly, with the ribs, vertebræ, and digital bones of saurians. but a full description of this interesting deposit, as its discovery belongs to the summer ramble of a year, the ramblings of which are not yet completed, must await some future time. chapter xiii. supplementary. supplementary--isolated reptile remains in eigg--small isles revisited--the betsey again--storm bound--tacking--becalmed--medusæ caught and described--rain--a shoal of porpoises--change of weather--the bed-ridden woman--the poor law act for scotland--geological excursion--basaltic columns--oölitic beds--abundance of organic remains--hybodus teeth--discovery of reptile remains _in situ_--musical sand of laig re-examined--explanation suggested--sail for isle ornsay--anchored clouds--a leak sprung--peril of the betsey--at work with pump and pails--safe in harbor--return to edinburgh. it is told of the "spectator," on his own high authority, that having "read the controversies of some great men concerning the antiquities of egypt, he made a voyage to grand cairo, on purpose to take the measure of a pyramid, and that, so soon as he had set himself right in that particular, he returned to his native country with great satisfaction." my love of knowledge has not carried me altogether so far, chiefly, i dare say, because my voyaging opportunities have not been quite so great. ever since my ramble of last year, however, i have felt, i am afraid, a not less interest in the geologic antiquities of small isles than that cherished by "spectator" with respect to the comparatively modern antiquities of egypt; and as, in a late journey to these islands the object of my visit involved but a single point, nearly as insulated as the dimensions of a pyramid, i think i cannot do better than shelter myself under the authority of the short-faced gentleman who wrote articles in the reign of queen anne. i had found in eigg, in considerable abundance and fine keeping, reptile remains of the oölite; but they had occurred in merely rolled masses, scattered along the beach. i had not discovered the bed in which they had been originally deposited, and could neither tell its place in the system, nor its relation to the other rocks of the island. the discovery was but a half-discovery,--the half of a broken medal, with the date on the missing portion. and so, immediately after the rising of the general assembly in june last [ ], i set out to revisit small isles, accompanied by my friend mr. swanson, with the determination of acquainting myself with the burial-place of the old oölitic reptiles, if it lay anywhere open to the light. we found the betsey riding in the anchoring ground at isle ornsay, in her foul-weather dishabille, with her topmast struck and in the yard, and her cordage and sides exhibiting in their weathered aspect the influence of the bleaching rains and winds of the previous winter. she was at once in an undress and getting old, and, as seen from the shore through rain and spray,--for the weather was coarse and boisterous,--she had apparently gained as little in her good looks from either circumstance as most other ladies do. we lay storm-bound for three days at isle ornsay, watching from the window of mr. swanson's dwelling the incessant showers sweeping down the loch. on the morning of saturday, the gale, though still blowing right ahead, had moderated; the minister was anxious to visit this island charge, after his absence of several weeks from them at the assembly; and i, more than half afraid that my term of furlough might expire ere i had reached my proposed scene of exploration, was as anxious as he; and so we both resolved, come what might, on doggedly beating our way adown the sound of sleat to small isles. if the wind does not fail us, said my friend, we have little more than a day's work before us, and shall get into eigg about midnight. we had but one of our seamen aboard, for john stewart was engaged with his potato crop at home; but the minister was content, in the emergency, to rank his passenger as an able-bodied seaman; and so, hoisting sail and anchor, we got under way, and, clearing the loch, struck out into the sound. we tacked in long reaches for several hours, now opening up in succession the deep withdrawing lochs of the mainland, now clearing promontory after promontory in the island district of sleat. in a few hours we had left a bulky schooner, that had quitted isle ornsay at the same time, full five miles behind us; but as the sun began to decline, the wind began to sink; and about seven o'clock, when we were nearly abreast of the rocky point of sleat, and about half-way advanced in our voyage, it had died into a calm; and for full twenty hours thereafter there was no more sailing for the betsey. we saw the sun set, and the clouds gather, and the pelting rain come down, and nightfall, and morning break, and the noon-tide hour pass by, and still were we floating idly in the calm. i employed the few hours of the saturday evening that intervened between the time of our arrest and nightfall, in fishing from our little boat for medusæ with a bucket. they had risen by myriads from the bottom as the wind fell, and were mottling the green depths of the water below and around far as the eye could reach. among the commoner kinds,--the kind with the four purple rings on the area of its flat bell, which ever vibrates without sound, and the kind with the fringe of dingy brown, and the long stinging tails, of which i have sometimes borne from my swimming excursions the nettle-like smart for hours,--there were at least two species of more unusual occurrence, both of them very minute. the one, scarcely larger than a shilling, bore the common umbiliferous form, but had its area inscribed by a pretty orange-colored wheel; the other, still more minute, and which presented in the water the appearance of a small hazel-nut of a brownish-yellow hue, i was disposed to set down as a species of beroe. on getting one caught, however, and transferred to a bowl, i found that the brownish-colored, melon-shaped mass, though ribbed like the beroe, did not represent the true outline of the animal; it formed merely the centre of a transparent gelatinous bell, which, though scarce visible in even the bowl, proved a most efficient instrument of motion. such were its contractile powers, that its sides nearly closed at every stroke, behind the opaque orbicular centre, like the legs of a vigorous swimmer; and the animal, unlike its more bulky congeners,--that, despite their slow but persevering flappings, seemed greatly at the mercy of the tide, and progressed all one way,--shot, as it willed, backwards, forwards, or athwart. as the evening closed, and the depths beneath presented a dingier and yet dingier green, until at length all had become black, the distinctive colors of the acelpha,--the purple, the orange, and the brown,--faded and disappeared, and the creatures hung out, instead, their pale phosphoric lights, like the lanterns of a fleet hoisted high to prevent collision in the darkness. now they gleamed dim and indistinct as they drifted undisturbed through the upper depths, and now they flamed out bright and green, like beaten torches, as the tide dashed them against the vessel's sides. i bethought me of the gorgeous description of coleridge, and felt all its beauty:-- "they moved in tracks of shining white, and when they reared, the elfish light fell off in hoary flakes. within the shadow of the ship i watched their rich attire,-- blue, glassy green, and velvet black: they curled, and swam, and every track was a flash of golden fire." a crew of three, when there are watches to set, divides wofully ill. as there was, however, nothing to do in the calm, we decided that our first watch should consist of our single seaman, and the second of the minister and his friend. the clouds, which had been thickening for hours, now broke in torrents of rain, and old alister got into his water-proof oil-skin and souwester, and we into our beds. the seams of the betsey's deck had opened so sadly during the past winter, as to be no longer water-tight, and the little cabin resounded drearily in the darkness, like some dropping cave, to the ceaseless patter of the leakage. we continued to sleep, however, somewhat longer than we ought,--for alister had been unwilling to waken the minister; but we at length got up, and, relieving watch the first from the tedium of being rained upon and doing nothing, watch the second was set to do nothing and be rained upon in turn. we had drifted during the night-time on a kindly tide, considerably nearer our island, which we could now see looming blue and indistinct through the haze some seven or eight miles away. the rain ceased a little before nine, and the clouds rose, revealing the surrounding lands, island and main,--rum, with its abrupt mountain-peaks,--the dark cuchullins of skye,--and, far to the south-east, where inverness bounds on argyllshire, some of the tallest hills in scotland,--among the rest, the dimly-seen ben-wevis. but long wreaths of pale gray cloud lay lazily under their summits, like shrouds half drawn from off the features of the dead, to be again spread over them, and we concluded that the dry weather had not yet come. a little before noon we were surrounded for miles by an immense but thinly-spread shoal of porpoises, passing in pairs to the south, to prosecute, on their own behalf, the herring fishing in lochfine or gareloch; and for a full hour the whole sea, otherwise so silent, became vocal with long-breathed blowings, as if all the steam-tenders of all the railways in britain were careering around us; and we could see slender jets of spray rising in the air on every side, and glossy black backs and pointed fins, that looked as if they had been fashioned out of kilkenny marble, wheeling heavily along the surface. the clouds again began to close as the shoal passed, but we could now hear in the stillness the measured sound of oars, drawn vigorously against the gunwale in the direction of the island of eigg, still about five miles distant, though the boat from which they rose had not yet come in sight. "some of my poor people," said the minister, "coming to tug us ashore!" we were boarded in rather more than half an hour after,--for the sounds in the dead calm had preceded the boat by miles,--by four active young men, who seemed wonderfully glad to see their pastor; and then, amid the thickening showers, which had recommenced heavy as during the night, they set themselves to tow us into the harbor. the poor fellows had a long and fatiguing pull, and were thoroughly drenched ere, about six o'clock in the evening, we had got up to our anchoring ground, and moored, as usual, in the open tideway between _eilan chasteil_ and the main island. there was still time enough for an evening discourse, and the minister, getting out of his damp clothes, went ashore and preached. the evening of sunday closed in fog and rain, and in fog and rain the morning of monday arose. the ceaseless patter made dull music on deck and skylight above, and the slower drip, drip, through the leaky beams, drearily beat time within. the roof of my bed was luckily water-tight; and i could look out from my snuggery of blankets on the desolations of the leakage, like bacon's philosopher surveying a tempest from the shore. but the minister was somewhat less fortunate, and had no little trouble in diverting an ill-conditioned drop that had made a dead set at his pillow. i was now a full week from edinburgh, and had seen and done nothing; and, were another week to pass after the same manner,--as, for aught that appeared, might well happen,--i might just go home again, as i had come, with my labor for my pains. in the course of the afternoon, however, the weather unexpectedly cleared up, and we set out somewhat impatiently through the wet grass, to visit a cave a few hundred yards to the west of _naomh fraingh_, in which it had been said the protestants of the island might meet for the purposes of religious worship, were they to be ejected from the cottage erected by mr. swanson, in which they had worshipped hitherto. we reëxamined, in the passing, the pitch stone dike mentioned in a former chapter, and the charnel cave of frances; but i found nothing to add to my former descriptions, and little to modify, save that perhaps the cave appeared less dark, in at least the outer half of its area, than it had seemed to me in the former year, when examined by torch-light, and that the straggling twilight, as it fell on the ropy sides, green with moss and mould, and on the damp bone-strewn floor, overmantled with a still darker crust, like that of a stagnant pool, seemed also to wear its tint of melancholy greenness, as if transmitted through a depth of sea-water. the cavern we had come to examine we found to be a noble arched opening in a dingy-colored precipice of augitic trap,--a cave roomy and lofty as the nave of a cathedral, and ever resounding to the dash of the sea; but though it could have amply accommodated a congregation of at least five hundred, we found the way far too long and difficult for at least the weak and the elderly, and in some places inaccessible at full flood; and so we at once decided against the accommodation which it offered. but its shelter will, i trust, scarce be needed. on our return to the betsey, we passed through a straggling group of cottages on the hill-side, one of which, the most dilapidated and smallest of the number, the minister entered, to visit a poor old woman, who had been bed-ridden for ten years. scarce ever before had i seen so miserable a hovel. it was hardly larger than the cabin of the betsey, and a thousand times less comfortable. the walls and roof, formed of damp grass-grown turf, with a few layers of unconnected stone in the basement tiers, seemed to constitute one continuous hillock, sloping upwards from foundation to ridge, like one of the lesser moraines of agassiz, save where the fabric here and there bellied outwards or inwards, in perilous dilapidation, that seemed but awaiting the first breeze. the low chinky door opened direct into the one wretched apartment of the hovel, which we found lighted chiefly by holes in the roof. the back of the sick woman's bed was so placed at the edge of the opening, that it had formed at one time a sort of partition to the portion of the apartment, some five or six feet square, which contained the fire-place; but the boarding that had rendered it such had long since fallen away, and it now presented merely a naked rickety frame to the current of cold air from without. within a foot of the bed-ridden woman's head there was a hole in the turf-wall, which was, we saw, usually stuffed with a bundle of rags, but which lay open as we entered, and which furnished a downward peep of sea and shore, and the rocky _eilan chasteil_, with the minister's yacht riding in the channel hard by. the little hole in the wall had formed the poor creature's only communication with the face of the external world for ten weary years. she lay under a dingy coverlet, which, whatever its original hue, had come to differ nothing in color from the graveyard earth, which must so soon better supply its place. what perhaps first struck the eye was the strange flatness of the bed-clothes, considering that a human body lay below: there seemed scarce bulk enough under them for a human skeleton. the light of the opening fell on the corpse-like features of the woman,--sallow, sharp, bearing at once the stamp of disease and of famine; and yet it was evident, notwithstanding, that they had once been agreeable,--not unlike those of her daughter, a good-looking girl of eighteen, who, when we entered, was sitting beside the fire. neither mother nor daughter had any english; but it was not difficult to determine, from the welcome with which the minister was greeted from the sick-bed, feeble as the tones were, that he was no unfrequent visitor. he prayed beside the poor creature, and, on coming away, slipped something into her hand. i learned that not during the ten years in which she had been bed-ridden had she received a single farthing from the proprietor, nor, indeed, had any of the poor of the island, and that the parish had no session-funds. i saw her husband a few days after,--an old worn-out man, with famine written legibly in his hollow cheek and eye, and on the shrivelled frame, that seemed lost in his tattered dress; and he reiterated the same sad story. they had no means of living, he said, save through the charity of their poor neighbors, who had so little to spare; for the parish or the proprietor had never given them anything. he had once, he added, two fine boys, both sailors, who had helped them; but the one had perished in a storm off the mull of cantyre, and the other had died of fever when on a west india voyage; and though their poor girl was very dutiful, and staid in their crazy hut to take care of them in their helpless old age, what other could she do in a place like eigg than just share with them their sufferings? it has been recently decided by the british parliament, that in cases of this kind the starving poor shall not be permitted to enter the law courts of the country, there to sue for a pittance to support life, until an intermediate newly-erected court, alien to the constitution, before which they must plead at their own expense, shall have first given them permission to prosecute their claims. and i doubt not that many of the english gentlemen whose votes swelled the majority, and made it such, are really humane men, friendly to an equal-handed justice, and who hold it to be the peculiar glory of the constitution, as well shown by de lolme, that it has not one statute-book for the poor, and another for the rich, but the same law and the same administration of law for all. they surely could not have seen that the principle of their poor law act for scotland sets the pauper beyond the pale of the constitution in the first instance, that he may be starved in the second. the suffering paupers of this miserable island cottage would have all their wants fully satisfied in the grave, long ere they could establish at their own expense, at edinburgh, their claim to enter a court of law. i know not a fitter case for the interposition of our lately formed "scottish association for the protection of the poor" than that of this miserable family; and it is but one of many which the island of eigg will be found to furnish. after a week's weary waiting, settled weather came at last; and the morning of tuesday rose bright and fair. my friend, whose absence at the general assembly had accumulated a considerable amount of ministerial labor on his hands, had to employ the day professionally; and as john stewart was still engaged with his potato crop, i was necessitated to sally out on my first geological excursion alone. in passing vessel-wards, on the previous year, from the _ru stoir_ to the farm-house of keill, along the escarpment under the cliffs, i had examined the shores somewhat too cursorily during the one-half of my journey, and the closing evening had prevented me from exploring them during the other half at all; and i now set myself leisurely to retrace the way backwards from the farm-house to the _stoir_. i descended to the bottom of the cliffs, along the pathway which runs between keill and the solitary midway shieling formerly described, and found that the basaltic columns over head, which had seemed so picturesque in the twilight, lost none of their beauty when viewed by day. they occur in forms the most beautiful and fantastic; here grouped beside some blind opening in the precipice, like pillars cut round the opening of a tomb, on some rock-front in petræa; there running in long colonnades, or rising into tall porticoes; yonder radiating in straight lines from some common centre, resembling huge pieces of fan-work, or bending out in bold curves over some shaded chasm, like rows of crooked oaks projecting from the steep sides of some dark ravine. the various beds of which the cliffs are composed, as courses of ashlar compose a wall, are of very different degrees of solidity: some are of hard porphyritic or basaltic trap; some of soft oölitic sandstone or shale. where the columns rest on a soft stratum, their foundations have in many places given way, and whole porticoes and colonnades hang perilously forward in tottering ruin, separated from the living rock behind by deep chasms. i saw one of these chasms, some five or six feet in width, and many yards in length, that descended to a depth which the eye could not penetrate; and another partially filled up with earth and stones, through which, along a dark opening not much larger than a chimney-vent, the boys of the island find a long descending passage to the foot of the precipice, and emerge into light on the edge of the grassy talus half-way down the hill. it reminded me of the tunnel in the rock through which imlac opened up a way of escape to rasselas from the happy valley,--the "subterranean passage," begun "where the summit hung over the middle part," and that "issued out behind the prominence." from the commencement of the range of cliffs, on half-way to the shieling, i found the shore so thickly covered up by masses of trap, the debris of the precipices above, that i could scarce determine the nature of the bottom on which they rested. i now, however, reached a part of the beach where the oölitic beds are laid bare in thin party-colored strata, and at once found something to engage me. organisms in vast abundance, chiefly shells and fragmentary portions of fishes, lie closely packed in their folds. one limestone bed, occurring in a dark shale, seems almost entirely composed of a species of small oyster; and some two or three other thin beds, of what appears to be either a species of small mytilus or avicula, mixed up with a few shells resembling large paludina, and a few more of the gaper family, so closely resembling existing species, that john stewart and alister at once challenged them as _smurslin_, the hebridean name for a well-known shell in these parts,--the _mya truncata_. the remains of fishes,--chiefly ganoid scales and the teeth of placoids,--lie scattered among the shells in amazing abundance. on the surface of a single fragment, about nine inches by five, which i detached from one of the beds, and which now lies before me, i reckon no fewer than twenty-five teeth, and twenty-two on the area of another. they are of very various forms,--some of them squat and round, like ill-formed small shot,--others spiky and sharp, not unlike flooring nails,--some straight as needles, some bent like the beak of a hawk,--some, like the palatal teeth of the acrodus of the lias, resemble small leeches; some, bearing a series of points ranged on a common base, like masts on the hull of a vessel, the tallest in the centre, belong to the genus hybodus. there is a palpable approximation in the teeth of the leech-like form to the teeth with the numerous points. some of the specimens show the same plicated structure common to both; and on some of the leech backs, if i may so speak, there are protuberant knobs, that indicate the places of the spiky points on the hybodent teeth. i have got three of each kind slit up by mr. george sanderson, and the internal structure appears to be the same. a dense body of bone is traversed by what seem innumerable roots, resembling those of woody shrubs laid bare along the sides of some forest stream. each internal opening sends off on every side its myriads of close-laid filaments; and nowhere do they lie so thickly as in the line of the enamel, forming, from the regularity with which they are arranged, a sort of framing to the whole section. it is probable that the hybodus,--a genus of shark which became extinct some time about the beginning of the chalk,--united, like the shark of port jackson, a crushing apparatus of palatal teeth to its lines of cutting ones. among the other remains of these beds i found a dense fragment of bone, apparently reptilian, and a curious dermal plate punctulated with thick-set depressions, bounded on one side by a smooth band, and altogether closely resembling some saddler's thimble that had been cut open and straightened. following the beds downwards along the beach, i found that one of the lowest which the tide permitted me to examine,--a bed colored with a tinge of red,--was formed of a denser limestone than any of the others, and composed chiefly of vast numbers of small univalves resembling neritæ. it was in exactly such a rock i had found, in the previous year, the reptile remains; and i now set myself, with no little eagerness, to examine it. one of the first pieces i tore up contained a well-preserved plesiosaurian vertebra; a second contained a vertebra and a rib; and, shortly after, i disinterred a large portion of a pelvis. i had at length found, beyond doubt, the reptile remains _in situ_. the bed in which they occur is laid bare here for several hundred feet along the beach, jutting out at a low angle among boulders and gravel, and the reptile remains we find embedded chiefly in its under side. it lies low in the oölite. all the stratified rocks of the island, with the exception of a small liasic patch, belong to the lower oölite, and the reptile-bed occurs deep in the base of the system,--low in its relation to the nether division, in which it is included. i found it nowhere rising to the level of high-water mark. it forms one of the foundation tiers of the island, which, as the latter rises over the sea in some places to the height of about fourteen hundred feet, its upper peaks and ridges must overlie the bones, making allowance for the dip, to the depth of at least sixteen hundred. even at the close of the oölitic period this sepulchral stratum must have been a profoundly ancient one. in working it out, i found two fine specimens of fish jaws, still retaining their ranges of teeth;--ichthyodorulites,--occipital plates of various forms, either reptile or ichthyic,--ganoid scales, of nearly the same varieties of pattern as those in the weald of morayshire,--and the vertebræ and ribs, with the digital, pelvic, and limb-bones, of saurians. it is not unworthy of remark, that in none of the beds of this deposit did i find any of the more characteristic shells of the system,--ammonites, belemnites, gryphites, or nautili. i explored the shores of the island on to the _ru stoir_, and thence to the bay of laig; but though i found detached masses of the reptile bed occurring in abundance, indicating that its place lay not far beyond the fall of ebb, in no other locality save the one described did i find it laid bare. i spent some time beside the bay of laig in reëxamining the musical sand, in the hope of determining the peculiarities on which its sonorous qualities depended. but i examined, and cross-examined it in vain. i merely succeeded in ascertaining, in addition to my previous observations, that the loudest sounds are elicited by drawing the hand slowly through the incoherent mass, in a segment of a circle, at the full stretch of the arm, and that the vibrations which produce them communicate a peculiar titillating sensation to the hand or foot by which they are elicited, extending in the foot to the knee, and in the hand to the elbow. when we pass the wet finger along the edge of an ale-glass partially filled with water, we see the vibrations thickly wrinkling the surface: the undulations which, communicated to the air, produce sound, render themselves, when communicated to the water, visible to the eye; and the titillating feeling seems but a modification of the same phenomenon acting on the nerves and fluids of the leg or arm. it appears to be produced by the wrinklings of the vibrations, if i may so speak, passing along sentient channels. the sounds will ultimately be found dependent, i am of opinion, though i cannot yet explain the principle, on the purely quartzose character of the sand, and the friction of the incoherent upper strata against under strata coherent and damp. i remained ten days in the island, and went over all my former ground, but succeeded in making no further discoveries. on the morning of wednesday, june th, we set sail for isle ornsay, with a smart breeze from the north-west. the lower and upper sky was tolerably clear, and the sun looked cheerily down on the deep blue of the sea; but along the higher ridges of the land there lay long level strata of what the meteorologists distinguish as parasitic clouds. when every other patch of vapor in the landscape was in motion, scudding shorewards from the atlantic before the still-increasing gale, there rested along both the scuir of eigg and the tall opposite ridge of the island, and along the steep peaks of rum, clouds that seemed as if anchored, each on its own mountain-summit, and over which the gale failed to exert any propelling power. they were stationary in the middle of the rushing current, when all else was speeding before it. it has been shown that these parasitic clouds are mere local condensations of strata of damp air passing along the mountain-summits, and rendered visible but to the extent in which the summits affect the temperature. instead of being stationary, they are ever-forming and ever-dissipating clouds,--clouds that form a few yards in advance of the condensing hill, and that dissipate a few yards after they have quitted it. i had nothing to do on deck, for we had been joined at eigg by john stewart; and so, after watching the appearance of the stationary clouds for some little time, i went below, and, throwing myself into the minister's large chair, took up a book. the gale meanwhile freshened, and freshened yet more; and the betsey leaned over till her lee chain-plate lay along in the water. there was the usual combination of sounds beneath and around me,--the mixture of guggle, clunk, and splash,--of low, continuous rush, and bluff, loud blow, which forms in such circumstances the voyager's concert. i soon became aware, however, of yet another species of sound, which i did not like half so well,--a sound as of the washing of a shallow current over a rough surface; and, on the minister coming below, i asked him, tolerably well prepared for his answer, what it might mean. "it means," he said, "that we have sprung a leak, and a rather bad one; but we are only some six or eight miles from the point of sleat, and must soon catch the land." he returned on deck, and i resumed my book. presently, however, the rush became greatly louder; some other weak patch in the betsey's upper works had given way, and anon the water came washing up from the lee side along the edge of the cabin floor. i got upon deck to see how matters stood with us; and the minister, easing off the vessel for a few points, gave instant orders to shorten sail, in the hope of getting her upper works out of the water, and then to unship the companion ladder, beneath which a hatch communicated with the low strip of hold under the cabin, and to bring aft the pails. we lowered our foresail; furled up the mainsail half-mast high; john stewart took his station at the pump; old alister and i, furnished with pails, took ours, the one at the foot, the other at the head, of the companion, to hand up and throw over; a young girl, a passenger from eigg to the mainland, lent her assistance, and got wofully drenched in the work; while the minister, retaining his station at the helm, steered right on. but the gale had so increased, that, notwithstanding our diminished breadth of sail, the betsey, straining hard in the rough sea, still lay in to the gunwale; and the water, pouring in through a hundred opening chinks in her upper works, rose, despite of our exertions, high over plank, and beam, and cabin-floor, and went dashing against beds and lockers. she was evidently filling, and bade fair to terminate all her voyagings by a short trip to the bottom. old alister, a seaman of thirty years' standing, whose station at the bottom of the cabin stairs enabled him to see how fast the water was gaining on the betsey, but not how the betsey was gaining on the land, was by no means the least anxious among us. twenty years previous he had seen a vessel go down in exactly similar circumstances, and in nearly the same place, and the reminiscence, in the circumstances, seemed rather an uncomfortable one. it had been a bad evening, he said, and the vessel he sailed in, and a sloop, her companion, were pressing hard to gain the land. the sloop had sprung a leak, and was straining, as if for life and death, under a press of canvas. he saw her outsail the vessel to which he belonged, but, when a few shots a-head she gave a sudden lurch, and disappeared from the surface instantaneously as a vanishing spectre, and neither sloop nor crew were ever more heard of. there are, i am convinced, few deaths less painful than some of those untimely and violent ones at which we are most disposed to shudder. we wrought so hard at pail and pump,--the occasion, too, was one of so much excitement, and tended so thoroughly to awaken our energies,--that i was conscious, during the whole time, of an exhilaration of spirits rather pleasurable than otherwise. my fancy was active, and active, strange as the fact may seem, chiefly with ludicrous objects. sailors tell regarding the flying dutchman, that he was a hard-headed captain of amsterdam, who, in a bad night and head wind, when all the other vessels of his fleet were falling back on the port they had recently quitted, obstinately swore that, rather than follow their example, he would keep beating about till the day of judgment. and the dutch captain, says the story, was just taken at his word, and is beating about still. when matters were at the worst with us, we got under the lea of the point of sleat. the promontory interposed between us and the roll of the sea; the wind gradually took off; and, after having seen the water gaining fast and steadily on us for considerably more than an hour, we, in turn, began to gain on the water. it came ebbing out of drawers and beds, and sunk downwards along pannels and table-legs,--a second retiring deluge; and we entered isle ornsay with the cabin-floor all visible, and less than two feet water in the hold. on the following morning, taking leave of my friend the minister, i set off, on my return homewards, by the skye steamer, and reached edinburgh on the evening of saturday. rambles of a geologist; or, ten thousand miles over the fossiliferous deposits of scotland. rambles of a geologist; or, ten thousand miles over the fossiliferous deposits of scotland.[ ] chapter i. embarkation--a foundered vessel--lateness of the harvest dependent on the geological character of the soil--a granite harvest and an old red harvest--cottages of redstone and of granite--arable soil of scotland the result of a geological grinding agency--locality of the famine of --mr. longmuir's fossils--geology necessary to a theologian--popularizers of science when dangerous--"constitution of man," and "vestiges of creation"--atop of the banff coach--a geologist's field equipment--the trespassing "stirk"--silurian schists inlaid with old red--bay of gamrie how formed--gardenstone--geological free-masonry illustrated--how to break an ichthyolite nodule--an old rhyme mended--a raised beach--fossil shells--scotland under water at the time of the boulder clays. from circumstances that in no way call for explanation, my usual exploratory ramble was thrown this year ( ) from the middle of july into the middle of september; and i embarked at granton for the north just as the night began to count hour against hour with the day. the weather was fine, and the voyage pleasant. i saw by the way, however, at least one melancholy memorial of a hurricane which had swept the eastern coasts of the island about a fortnight before, and filled the provincial newspapers with paragraphs of disaster. nearly opposite where the red head lifts its mural front of old red sandstone a hundred yards over the beach, the steamer passed a foundered vessel, lying about a mile and a half off the land, with but her topmast and the point of her peak over the surface. her vane, still at the mast-head, was drooping in the calm; and its shadow, with that of the fresh-colored _spar_ to which it was attached, white atop and yellow beneath, formed a well-defined undulatory strip on the water, that seemed as if ever in the process of being rolled up, and yet still retained its length unshortened. every recession of the swell showed a patch of mainsail attached to the peak: the sail had been hoisted to its full stretch when the vessel went down. and thus, though no one survived to tell the story of her disaster, enough remained to show that she had sprung a leak when straining in the gale, and that, when staggering under a press of canvas towards the still distant shore, where, by stranding her, the crew had hoped to save at least their lives, she had disappeared with a sudden lurch, and all aboard had perished. i remembered having read, among other memorabilia of the hurricane, without greatly thinking of the matter, that "a large sloop had foundered off the red head,--name unknown." but the minute portion of the wreck which i saw rising over the surface, to certify, like some frail memorial in a churchyard, that the dead lay beneath, had an eloquence in it which the words wanted, and at once sent the imagination back to deal with the stern realities of the disaster, and the feelings abroad to expatiate over saddened hearths and melancholy homesteads, where for many a long day the hapless perished would be missed and mourned, but where the true story of their fate, though too surely guessed at, would never be known. the harvest had been early; and on to the village of stonehaven, and a mile or two beyond, where the fossiliferous deposits end and the primary begin, the country presented from the deck only a wide expanse of stubble. every farm-steading we passed had its piled stack-yard; and the fields were bare. but the line of demarcation between the old red sandstone and the granitic districts formed also a separating line between an earlier and later harvest; the fields of the less kindly subsoil derived from the primary rocks were, i could see, still speckled with sheaves; and, where the land lay high, or the exposure was unfavorable, there were reapers at work. all along in the course of my journey northward from aberdeen i continued to find the country covered with shocks, and laborers employed among them; until, crossing the spey, i entered on the fossiliferous districts of moray; and then, as in the south, the champaign again showed a bare breadth of stubble, with here and there a ploughman engaged in turning it down. the traveller bids farewell at stonehaven to not only the old red sandstone and the early-harvest districts, but also to the rich wheat-lands of the country, and does not again fairly enter upon them until, after travelling nearly a hundred miles, he passes from banffshire into the province of moray. he leaves behind him at the same line the wheat-fields and the cottages built of red stone, to find only barley and oats, and here and there a plot of rye, associated with cottages of granite and gneiss, hyperstene and mica schist; but on crossing the spey, the red cottages reäppear, and fields of rich wheat-land spread out around them, as in the south. the circumstance is not unworthy the notice of the geologist. it is but a tedious process through which the minute lichen, settling on a surface of naked stone, forms in the course of ages a soil for plants of greater bulk and a higher order; and had scotland been left to the exclusive operation of this slow agent, it would be still a rocky desert, with perhaps here and there a strip of alluvial meadow by the side of a stream, and here and there an insulated patch of rich soil among the hollows of the crags. it might possess a few gardens for the spade, but no fields for the plough. we owe our arable land to that comparatively modern geologic agent, whatever its character, that crushed, as in a mill, the upper parts of the surface-rocks of the kingdom, and then overlaid them with their own debris and rubbish to the depth of from one to forty yards. this debris, existing in one locality as a boulder-clay more or less finely comminuted, in another as a grossly pounded gravel, forms, with few exceptions, that subsoil of the country on which the existing vegetation first found root; and, being composed mainly of the formations on which it more immediately rests, it partakes of their character,--bearing a comparatively lean and hungry aspect over the primary rocks, and a greatly more fertile one over those deposits in which the organic matters of earlier creations lie diffused. saxon industry has done much for the primary districts of aberdeen and banffshires, though it has failed to neutralize altogether the effects of causes which date as early as the times of the old red sandstone; but in the highlands, which belong almost exclusively to the non-fossiliferous formations, and which were, on at least the western coasts, but imperfectly subjected to that grinding process to which we owe our subsoils, the poor celt has permitted the consequences of the original difference to exhibit themselves in full. if we except the islands of the inner hebrides, the famine of was restricted in scotland to the primary districts. i made it my first business, on landing in aberdeen, to wait on my friend mr. longmuir, that i might compare with him a few geological notes, and benefit by his knowledge of the surrounding country. i was, however, unlucky enough to find that he had gone, a few days before, on a journey, from which he had not yet returned; but, through the kindness of mrs. longmuir, to whom i took the liberty of introducing myself, i was made free of his stone-room, and held half an hour's conversation with his scotch fossils of the chalk. these had been found, as the readers of the _witness_ must remember from his interesting paper on the subject, on the hill of dudwick, in the neighborhood of ellon, and were chiefly impressions--some of them of singular distinctness and beauty--in yellow flint. i saw among them several specimens of the inoceramus, a thin-shelled, ponderously-hinged conchifer, characteristic of the cretaceous group, but which has no living representative; with numerous flints, traversed by rough-edged, bifurcated hollows, in which branched sponges had once lain; a well-preserved pecten; the impressions of spines of echini of at least two distinct species; and the nicely-marked impression of part of a cidaris, with the balls on which the sockets of the club-like spines had been fitted existing in the print as spherical moulds, in which shot might be cast, and with the central ligamentary depression, which in the actual fossil exists but as a minute cavity, projecting into the centre of each hollow sphere, like the wooden fusee into the centre of a bomb-shell. this latter cast, fine and sharp as that of a medal taken in sulphur, seems sufficient of itself to establish two distinct points: in the first place, that the siliceous matter of which the flint is composed, though now so hard and rigid, must, in its original condition, have been as impressible as wax softened to receive the stamp of the seal; and, in the next, that though it was thus yielding in its character, it could not have greatly shrunk in the process of hardening. i looked with no little interest on these remains of a scotch formation now so entirely broken up, that, like those ruined cities of the east which exist but as mere lines of wrought material barring the face of the desert, there has not "been left one stone of it upon another," but of which the fragments, though widely scattered, bear imprinted upon them, like the stamped bricks of babylon, the story of its original condition, and a record of its _founders_. all mr. longmuir's cretaceous fossils from the hill of dudwick are of flint,--a substance not easily ground down by the denuding agencies. i found several other curious fossils in mr. longmuir's collection. greatly more interesting, however, than any of the specimens which it contains, is the general fact, that it should be the collection of a free church minister, sedulously attentive to the proper duties of his office, but who has yet found time enough to render himself an accomplished geologist; and whose week-day lectures on the science attract crowds, who receive from them, in many instances, their first knowledge of the strange revolutions of which our globe has been the subject, blent with the teachings of a wholesome theology. the present age, above all that has gone before, is peculiarly the age of physical science; and of all the physical sciences, not excepting astronomy itself, geology, though it be a fact worthy of notice, that not one of our truly accomplished geologists is an infidel, is the science of which infidelity has most largely availed itself. and as the theologian in a metaphysical age,--when skepticism, conforming to the character of the time, disseminated its doctrines in the form of nicely abstract speculations,--had, in order that the enemy might be met in his own field, to become a skilful metaphysician, he must now, in like manner, address himself to the tangibilities of natural history and geology, if he would avoid the danger and disgrace of having his flank turned by every sciolist in these walks whom he may chance to encounter. it is those identical bastions and outworks that are _now_ attacked, which must be _now_ defended; not those which were attacked some eighty or a hundred years ago. and as he who succeeds in first mixing up fresh and curious truths, either with the objections by which religion is assailed or the arguments by which it is defended, imparts to his cause all the interest which naturally attaches to these truths, and leaves to his opponent, who passes over them after him as at second hand, a subject divested of the fire-edge of novelty, i can deem mr. longmuir well and not unprofessionally employed, in connecting with a sound creed the picturesque marvels of one of the most popular of the sciences, and by this means introducing them to his people, linked, from the first, with right associations. according to the old fiction, the look of the basilisk did not kill unless the creature saw before it was seen;--its mere _return_ glance was harmless; and there is a class of thoroughly dangerous writers who in this respect resemble the basilisk. it is perilous to give them a first look of the public. they are formidable simply as the earliest popularizers of some interesting science, or the first promulgators of some class of curious little-known facts, with which they mix up their special contributions of error,--often the only portion of their writings that really belongs to themselves. nor is it at all so easy to _counteract_ as to _confute_ them. a masterly confutation of the part of their works truly their own may, from its subject, be a very unreadable book: it can have but the insinuated poison to deal with, unmixed with the palatable pabulum in which the poison has been conveyed; and mere treatises on poisons, whether moral or medical, are rarely works of a very delectable order. it seems to be on this principle that there exists no confutation of the "constitution of man" in which the ordinary reader finds amusement to carry him through; whereas the work itself, full of curious miscellaneous information, is eminently readable; and that the "vestiges of creation,"--a treatise as entertaining as the "arabian nights,"--bids fair, not from the amount of error which it contains, but from the amount of fresh and interestingly told truth with which the error is mingled, to live and do mischief when the various solidly-scientific replies which it has called forth are laid upon the shelf. both the "constitution" and the "vestiges" had the advantage, so essential to the basilisk, of taking the first glance of the public on their respective subjects; whereas their confutators have been able to render them back but mere _return_ glances. the only efficiently counteractive mode of looking down the danger, in cases of this kind, is the mode adopted by mr. longmuir. there was a smart frost next morning; and, for a few hours, my seat on the top of the banff coach, by which i travelled across the country to where the gamrie and banff roads part company, was considerably more cool than agreeable. but the keen morning improved into a brilliant day, with an atmosphere transparent as if there had been no atmosphere at all, through which the distant objects looked out as sharp of outline, and in as well-defined light and shadow, as if they had occupied the background, not of a scotch, but of an italian landscape. a few speck-like sails, far away on the intensely blue sea, which opened upon us in a stretch of many leagues, as we surmounted the moory ridge over macduff, gleamed to the sun with a radiance bright as that of the sparks of a furnace blown to a white heat. the land, uneven of surface, and open, and abutting in bold promontories on the frith, still bore the sunny hue of harvest, and seemed as if stippled over with shocks from the ridgy hill summits, to where ranges of giddy cliffs flung their shadows across the beach. i struck off for gamrie by a path that runs eastward, nearly parallel to the shore,--which at one or two points it overlooks from dark-colored cliffs of grauwacke slate,--to the fishing village of gardenstone. my dress was the usual fatigue suit of russet, in which i find i can work amid the soil of ravines and quarries with not only the best effect, but with even the least possible sacrifice of appearance: the shabbiest of all suits is a good suit spoiled. my hammer-shaft projected from my pocket; a knapsack, with a few changes of linen, slung suspended from my shoulders; a strong cotton umbrella occupied my better hand; and a gray maud, buckled shepherd-fashion aslant the chest, completed my equipment. there were few travellers on the road, which forked off on the hill-side a short mile away, into two branches, like a huge letter y, leaving me uncertain which branch to choose; and i made up my mind to have the point settled by a woman of middle age, marked by a hard, _manly_ countenance, who was coming up towards me, bound apparently for the banff or macduff market, and stooping under a load of dairy produce. she too, apparently, had her purpose to serve or point to settle; for as we met, she was the first to stand; and, sharply scanning my appearance and aspect at a glance, she abruptly addressed me. "honest man," she said, "do you see yon house wi' the chimla?" "that house with the farm-steadings and stacks beside it?" i replied. "yes." "then i'd be obleeged if ye wald just stap in as ye'r gaing east the gate, and tell _our_ folk that the stirk has gat fra her tether, an' 'ill brak on the wat clover. tell them to sen' for her _that_ minute." i undertook the commission; and, passing the endangered stirk, that seemed luxuriating, undisturbed by any presentiment of impending peril, amid the rich swathe of a late clover crop, still damp with the dews of the morning frost, i tapped at the door of the farm-house, and delivered my message to a young good-looking girl, in nearly the words of the woman:--"the gude-wife bade me tell _them_," i said, "to send that instant for the stirk, for she had gat fra her tether, and would brak on the wat clover." the girl blushed just a very little, and thanked me; and then, after obliging me, in turn, by laying down for me my proper route,--for i had left the question of the forked road to be determined at the farm-house,--she set off at high speed, to rescue the unconscious stirk. a walk of rather less than two hours brought me abreast of the bay of gamrie,--a picturesque indentation of the coast, in the formation of which the agency of the old denuding forces, operating on deposits of unequal solidity, may be distinctly traced. the surrounding country is composed chiefly of silurian schists, in which there is deeply inlaid a detached strip of mouldering old red sandstone, considerably more than twenty miles in length, and that varies from two to three miles in breadth. it seems to have been let down into the more ancient formation,--like the keystone of a bridge into the ringstones of the arch when the work is in the act of being completed,--during some of those terrible convulsions which cracked and rent the earth's crust, as if it had been an earthen pipkin brought to a red heat and then plunged into cold water. its consequent occurrence in a lower tier of the geological edifice than that to which it originally belonged has saved it from the great denudation which has swept from the surface of the surrounding country the tier composed of its contemporary beds and strata, and laid bare the grauwacke on which this upper tier rested. but where it presents its narrow end to the sea, as the older houses in our more ancient scottish villages present their gables to the street, the waves of the german ocean, by incessantly charging against it, propelled by the tempests of the stormy north, have hollowed it into the bay of gamrie, and left the more solid grauwacke standing out in bold promontories on either side, as the headlands of gamrie and troup. in passing downwards on the fishing village of gardenstone, mainly in the hope of procuring a guide to the ichthyolite beds, i saw a laborer at work with a pickaxe, in a little craggy ravine, about a hundred yards to the left of the path, and two gentlemen standing beside him. i paused for a moment, to ascertain whether the latter were not brother-workers in the geologic field. "hilloa!--here,"--shouted out the stouter of the two gentlemen, as if, by some _clairvoyant_ faculty, he had dived into my secret thought; "come here." i went down into the ravine, and found the laborer engaged in disinterring ichthyolitic nodules out of a bed of gray stratified clay, identical in its composition with that of the cromarty fish-beds; and a heap of freshly-broken nodules, speckled with the organic remains of the lower old red sandstone,--chiefly occipital plates and scales,--lay beside him. "know you aught of these?" said the stouter gentleman, pointing to the heap. "a little," i replied; "but your specimens are none of the finest. here, however, is a dorsal plate of coccosteus; and here a scattered group of scales of osteolepis; and here the occipital plates of _cheirolepis cummingiæ_; and here the spine of the anterior dorsal of _diplacanthus striatus_." my reading of the fossils was at once recognized, like the mystic sign of the freemason, as establishing for me a place among the geologic brotherhood; and the stout gentleman producing a spirit-flask and a glass, i pledged him and his companion in a bumper. "was i not sure?" he said, addressing his friend: "i knew by the cut of his jib, notwithstanding his shepherd's plaid, that he was a wanderer of the scientific cast." we discussed the peculiarities of the deposit, which, in its mineralogical character, and generically in that of its organic contents, resembles, i found, the fish-beds of cromarty (though, curiously enough, the intervening contemporary deposits of moray and the western parts of banffshire differ widely, in at least their chemistry, from both); and we were right good friends ere we parted. to men who travel for amusement, incident is incident, however trivial in itself, and always worth something. i showed the younger of the two geologists my mode of breaking open an ichthyolitic nodule, so as to secure the best possible section of the fish. "ah," he said, as he marked a style of handling the hammer which, save for the fifteen years' previous practice of the operative mason, would be perhaps less complete,--"ah, you must have broken open a great many." his own knowledge of the formation and its ichthyolites had been chiefly derived, he added, from a certain little treatise on the "old red sandstone," rather popular than scientific, which he named. i of course claimed no acquaintance with the work; and the conversation went on. the ill luck of my new friends, who had been toiling among the nodules for hours without finding an ichthyolite worth transferring to their bag, showed me that, without excavating more deeply than my time allowed, i had no chance of finding good specimens. but, well content to have ascertained that the ichthyolite bed of gamrie is identical in its composition, and, generically at least, in its organisms, with the beds with which i was best acquainted, i rose to come away. the object which i next proposed to myself was, to determine whether, as at eathie and cromarty, the fossils here appear not only on the hill-side, but also crop out along the shore. on taking leave, however, of the geologists, i was reminded by the younger of what i might have otherwise forgotten,--a raised beach in the immediate neighborhood (first described by mr. prestwich, in his paper on the gamrie ichthyolites), which contains shells of the existing species at a higher level than elsewhere,--so far as is yet known,--on the east coast of scotland. and, kindly conducting me till he had brought me full within view of it, we parted. the ichthyolites which i had just been laying open occur on the verge of that strathbogie district in which the church controversy raged so hot and high; and by a common enough trick of the associative faculty, they now recalled to my mind a stanza which memory had somehow caught when the battle was at the fiercest. it formed part of a satiric address, published in an aberdeen newspaper, to the not very respectable non-intrusionists who had smoked tobacco and drank whisky in the parish church at culsalmond, on the day of a certain forced settlement there, specially recorded by the clerks of the justiciary court. "tobacco and whisky cost siller, and meal is but scanty at hame; but gang to the stane-mason m----r, wi' old red sandstone fish he'll fill your wame." rather a dislocated line that last, i thought, and too much in the style in which zachary boyd sings "pharaoh and the pascal." and as it is wrong to leave the beast of even an enemy in the ditch, however long its ears, i must just try and set it on its legs. would it not run better thus? "tobacco and whisky cost siller, an' meal is but scanty at hame; but gang to the stane-mason m----r," he'll pang wi' ichth'ólites your wame,-- wi' _fish_!! as agassiz has ca'ed 'em, in greek, like themsel's, _hard_ an' _odd_, that were baked in stane pies afore adam gaed names to the haddocks and cod. bad enough as rhyme, i suspect; but conclusive as evidence to prove that the animal spirits, under the influence of the bracing walk, the fine day, and the agreeable recounter at the fish-beds,--not forgetting the half-gill bumper,--had mounted very considerably above their ordinary level at the editorial desk. the raised beach may be found on the slopes of a grass-covered eminence, once the site of an ancient hill-fort, and which still exhibits, along the rim-like edge of the flat area atop, scattered fragments of the vitrified walls. a general covering of turf restricted my examination of the shells to one point, where a land-slip on a small scale had laid the deposit bare; but i at least saw enough to convince me that the debris of the shell-fish used of old as food by the garrison had not been mistaken for the remains of a raised beach,--a mistake which in other localities has occurred, i have reason to believe, oftener than once. the shells, some of them exceedingly minute, and not of edible species, occur in layers in a siliceous stratified sand, overlaid by a bed of bluish-colored silt. i picked out of the sand two entire specimens of a full-grown fusus, little more than half an inch in length,--the _fusus turricola_; and the greater number of the fragments that lay bleaching at the foot of the broken slope, in a state of chalky friability, seemed to be fragments of those smaller bivalves, belonging to the genera _donax_, _venus_, and _mactra_, that are so common on flat sandy shores. but when the sea washed over these shells, they could have been the denizens of at least no _flat_ shore. the descent on which they occur sinks downwards to the existing beach, over which it is elevated at this point two hundred and thirty feet, at an angle with the horizon of from thirty-five to forty degrees. were the land to be now submerged to where they appear on the hill-side, the bay of gamrie, as abrupt in its slopes as the upper part of loch lomond or the sides of loch ness, would possess a depth of forty fathoms water at little more than a hundred yards from the shore. i may add, that i could trace at this height no marks of such a continuous terrace around the sides of the bay as the waves would have infallibly excavated in the diluvium, had the sea stood at a level so high, or, according to the more prevalent view, had the land stood at a level so low, for any considerable time; though the green banks which sweep around the upper part of the inflection, unscarred by the defacing plough, would scarce have failed to retain some mark of where the surges had broken, had the surges been long there. whatever may in this special case be the fact, however, i cannot doubt that in the comparatively modern period of the boulder clays, scotland lay buried under water to a depth at least five times as great as the space between this ancient sea-beach and the existing tide-line. chapter ii. character of the rocks near gardenstone--a defunct father-lasher--a geological inference--village of gardenstone--the drunken scot--gardenstone inn--lord gardenstone--a tempest threatened--the author's ghost story--the lady in green--her appearance and tricks--the rescued children--the murdered peddler and his pack--where the green dress came from--village of macduff--peculiar appearance of the beach at the mouth of the deveron--dr. emslie's fossils--_pterichthys quadratus_--argillaceous deposit of blackpots--pipe-laying in scotland--fossils of blackpots clay--mr. longmuir's description of them--blackpots deposit a re-formation of a liasic patch--period of its formation. i lingered on the hill-side considerably longer than i ought; and then, hurrying downwards to the beach, passed eastwards under a range of abrupt, mouldering precipices of red sandstone, to the village. from the lie of the strata, which, instead of inclining coastwise, dip towards the interior of the country, and present in the descent seawards the outcrop of lower and yet lower deposits of the formation, i found it would be in vain to look for the ichthyolite beds along the shore. they may possibly be found, however, though i lacked time to ascertain the fact, along the sides of a deep ravine, which occurs near an old ecclesiastical edifice of gray stone, perched, nest-like, half-way up the bank, on a green hummock that overlooks the sea. the rocks, laid bare by the tide, belong to the bed of coarse-grained red sandstone, varying from eighty to a hundred and fifty feet in thickness, which lies between the lower fish-bed and the great conglomerate, and which, in not a few of its strata, passes itself into a species of conglomerate, different only from that which it overlies, in being more finely comminuted. the continuity of this bed, like that of the deposit on which it rests, is very remarkable. i have found it occurring at many various points, over an area at least ten thousand square miles in extent, and bearing always the same well-marked character of a more thoroughly ground-down conglomerate than the great conglomerate on which it reposes. the underlying bed is composed of broken fragments of the rocks below, crushed, as if by some imperfect rudimentary process, like that which in a mill merely breaks the grain; whereas, in the bed above, a portion of the previously-crushed materials seems to have been subjected to some further attritive process, like that through which, in the mill, the broken grain is ground down into meal or flour. as i passed onwards, i saw, amid a heap of drift-weed stranded high on the beach by the previous tide, a defunct father-lasher, with the two defensive spines which project from its opercles stuck fast into little cubes of cork, that had floated its head above water, as the tyro-swimmer floats himself upon bladders; and my previous acquaintance with the habits of a fishing village enabled me at once to determine why and how it had perished. though almost never used as food on the eastern coast of scotland, it had been inconsiderate enough to take the fisherman's bait, as if it had been worthy of being eaten; and he had avenged himself for the trouble it had cost him, by mounting it on cork, and sending it off, to wander between wind and water, like the flying dutchman, until it died. was there ever on earth a creature save man that could have played a fellow-mortal a trick at once so ingeniously and gratuitously cruel? or what would be the proper inference, were i to find one of the many-thorned ichthyolites of the lower old red sandstone with the spines of its pectorals similarly fixed on cubes of lignite?--that there had existed in these early ages not merely _physical death_, but also _moral evil_; and that the being who perpetrated the evil could not only inflict it simply for the sake of the pleasure he found in it, and without prospect of advantage to himself, but also by so adroitly reversing, fiend-like, the purposes of the benevolent designer, that the weapons given for the defence of a poor harmless creature should be converted into the instruments of its destruction. it was not without meaning that it was forbidden by the law of moses to seethe a kid in its mother's milk. a steep bulwark in front, against which the tide lashes twice every twenty-four hours,--an abrupt hill behind,--a few rows of squalid cottages built of red sandstone, much wasted by the keen sea-winds,--a wilderness of dunghills and ruinous pig-styes,--women seated at the doors, employed in baiting lines or mending nets,--groups of men lounging lazily at some gable-end fronting the sea,--herds of ragged children playing in the lanes,--such are the components of the fishing village of gardenstone. from the identity of name, i had associated the place with that lord gardenstone of the court of sessions who published, late in the last century, a volume of "miscellanies in prose and verse," containing, among other clever things, a series of tart criticisms on english plays, transcribed, it was stated in the preface, from the margins and fly-leaves of the books of a "small library kept open by his lordship" for the amusement of travellers at the inn of some village in his immediate neighborhood; and taking it for granted, somehow, that gardenstone was the village, i was looking around me for the inn, in the hope that where his lordship had opened a library i might find a dinner. but failing to discern it, i addressed myself on the subject to an elderly man in a pack-sheet apron, who stood all alone, looking out upon the sea, like napoleon, in the print, from a projection of the bulwark. he turned round, and showed, by an unmistakable expression of eye and feature, that he was what the servant girl in "guy mannering" characterizes as "very particularly drunk,"--not stupidly, but happily, funnily, conceitedly drunk, and full of all manner of high thoughts of himself. "it'll be an awfu' coorse nicht," he said, "fra the sea." "very likely," i replied, reiterating my query in a form that indicated some little confidence of receiving the needed information; "i daresay you could point me out the public-house here?" "aweel, i wat, that i can; but what's that?" pointing to the straps of my knapsack;--"are ye a sodger on the queen's account, or ye'r ain?" "on my own, to be sure; but have ye a public-house here?" "ay, twa; ye'll be a traveller?" "o yes, great traveller, and very hungry: have i passed the best public-house?" "ay; and ye'll hae come a gude stap the day?" a woman came up, with spectacles on nose, and a piece of white seam-work in her hand; and, cutting short the dialogue by addressing myself to her, she at once directed me to the public-house. "hoot, gude-wife," i heard the man say, as i turned down the street, "we suld ha'e gotten mair oot o' him. he's a great traveller yon, an' has a gude scots tongue in his head." travellers, save when, during the herring season, an occasional fish-curer comes the way, rarely bait at the gardenstone inn; and in the little low-browed room, with its windows in the thatch, into which, as her best, the land-lady ushered me, i certainly found nothing to identify the _locale_ with that chosen by the literary lawyer for his open library. but, according to ferguson, though "learning was scant, provision was good;" and i dined sumptuously on an immense platter of fried flounders. there was a little bit of cold pork added to the fare; but, aware from previous experience of the pisciverous habits of the swine of a fishing village, i did what i knew the defunct pig must have very frequently done before me,--satisfied a keenly-whetted appetite on fish exclusively. i need hardly remind the reader that lord gardenstone's inn was not that of gardenstone, but that of laurence-kirk,--the thriving village which it was the special ambition of this law-lord of the last century to create; and which, did it produce only its famed snuff-boxes, with the invisible hinges, would be rather a more valuable boon to the country than that secured to it by those law-lords of our own days, who at one fell blow disestablished the national religion of scotland, and broke off the only handle by which their friends the politicians could hope to _manage_ the country's old vigorous presbyterianism. meanwhile it was becoming apparent that the man with the apron had as shrewdly anticipated the character of the coming night as if he had been soberer. the sun, ere its setting, disappeared in a thick leaden haze, which enveloped the whole heavens; and twilight seemed posting on to night a full hour before its time. i settled a very moderate bill, and set off under the cliffs at a round pace, in the hope of scaling the hill, and gaining the high road atop which leads to macduff, ere the darkness closed. i had, however, miscalculated my distance; i, besides, lost some little time in the opening of the deep ravine to which i have already referred as that in which possibly the fish-beds may be found cropping out; and i had got but a little beyond the gray ecclesiastical ruin, with its lonely burying-ground, when the tempest broke and the night fell. one of the last objects which i saw, as i turned to take a farewell look of the bay of gamrie, was the magnificent promontory of troup head, outlined in black on a ground of deep gray, with its two terminal stacks standing apart in the sea. and straightway, through one of those tricks of association so powerful in raising, as if from the dead, buried memories of things of which the mind has been oblivious for years, there started up in recollection the details of an ancient ghost-story, of which i had not thought before for perhaps a quarter of a century. it had been touched, i suppose, in its obscure, unnoted corner, as ithuriel touched the toad, by the apparition of the insulated stacks of troup, seen dimly in the thickening twilight over the solitary burying-ground. for it so chances that one of the main incidents of the story bears reference to an insulated sea-stack; and it is connected altogether, though i cannot fix its special locality, with this part of the coast. the story had been long in my mother's family, into which it had been originally brought by a great-grandfather of the writer, who quitted some of the seaport villages of banffshire for the northern side of the moray frith, about the year ; and, when pushing on in the darkness, straining as i best could, to maintain a sorely-tried umbrella against the capricious struggles of the tempest, that now tatooed furiously upon its back as if it were a kettle-drum, and now got underneath its stout ribs, and threatened to send it up aloft like a balloon, and anon twisted it from side to side, and strove to turn it inside out, like a kilmarnock night-cap,--i employed myself in arranging in my mind the details of the narrative, as they had been communicated to me half an age before by a female relative. the opening of the story, though it existed long ere the times of sir walter scott or the waverly novels, bears some resemblance to the opening in the "monastery," of the story of the white lady of avenel. the wife of a banffshire proprietor of the minor class had been about six months dead, when one of her husband's ploughmen, returning on horseback from the smithy, in the twilight of an autumn evening, was accosted, on the banks of a small stream, by a stranger lady, tall and slim, and wholly attired in green, with her face wrapped up in the hood of her mantle, who requested to be taken up behind him on the horse, and carried across. there was something in the tones of her voice that seemed to thrill through his very bones, and to insinuate itself, in the form of a chill fluid, between his skull and the scalp. the request, too, appeared a strange one; for the rivulet was small and low, and could present no serious bar to the progress of the most timid traveller. but the man, unwilling ungallantly to offend a lady, turned his horse to the bank, and she sprang up lightly behind him. she was, however, a personage that could be better seen than felt; she came in contact with the ploughman's back, he said, as if she had been an ill-filled sack of wool; and when, on reaching the opposite side of the streamlet, she leaped down as slightly as she had mounted, and he turned fearfully round to catch a second glimpse of her, it was in the conviction that she was a creature considerably less earthly in her texture than himself. she had opened, with two pale, thin arms, the enveloping hood, exhibiting a face equally pale and thin, which seemed marked, however, by the roguish, half-humorous expression of one who had just succeeded in playing off a good joke. "my dead mistress!!" exclaimed the ploughman. "yes, john, _your mistress_," replied the ghost. "but ride home, my bonny man, for it's growing late: you and i will be better acquainted ere long." john accordingly rode home and told his story. next evening, about the same hour, as two of the laird's servant-maids were engaged in washing in an out-house, there came a slight tap to the door. "come in," said one of the maids; and the lady entered, dressed, as on the previous night, in green. she swept past them to the inner part of the washing-room; and, seating herself on a low bench, from which, ere her death, she used occasionally to superintend their employment, she began to question them, as if still in the body, about the progress of their work. the girls, however, were greatly too frightened to make any reply. she then visited an old woman who had nursed the laird, and to whom she used to show, ere her departure, greatly more kindness than her husband. and she now seemed as much interested in her welfare as ever. she inquired whether the laird was kind to her, and looking round her little smoky cottage, regretted she should be so indifferently lodged, and that her cupboard, which was rather of the emptiest at the time, should not be more amply furnished. for nearly a twelvemonth after, scarce a day passed in which she was not seen by some of the domestics; never, however, except on one occasion, after the sun had risen, or before it had set. the maids could see her, in the gray of the morning flitting like a shadow round their beds, or peering in upon them at night through the dark window-panes, or at half-open doors. in the evening she would glide into the kitchen or some of the out-houses,--one of the most familiar and least dignified of her class that ever held intercourse with mankind,--and inquire of the girls how they had been employed during the day; often, however, without obtaining an answer, though from a cause different from that which had at first tied their tongues. for they had become so regardless of her presence, viewing her simply as a troublesome mistress, who had no longer any claim to be heeded, that when she entered, and they had dropped their conversation, under the impression that their visitor was a creature of flesh and blood like themselves, they would again resume it, remarking that the entrant was "only the green lady." though always cadaverously pale, and miserable looking, she affected a joyous disposition, and was frequently heard to laugh, even when invisible. at one time, when provoked by the studied silence of a servant girl, she flung a pillow at her head, which the girl caught up and returned; at another, she presented her first acquaintance, the ploughman, with what seemed to be a handful of silver coin, which he transferred to his pocket, but which, on hearing her laugh, he drew out, and found to be merely a handful of slate shivers. on yet another occasion, the man, when passing on horseback through a clump of wood, was repeatedly struck from behind the trees by little pellets of turf; and, on riding into the thicket, he found that his assailant was the green lady. to her husband she never appeared; but he frequently heard the tones of her voice echoing from the lower apartments, and the faint peal of her cold, unnatural laugh. one day at noon, a year after her first appearance, the old nurse was surprised to see her enter the cottage; as all her previous visits had been made early in the morning or late in the evening; whereas now,--though the day was dark and lowering, and a storm of wind and rain had just broken out,--still it _was_ day. "mammie," she said, "i cannot open the heart of the laird, and i have nothing of my own to give you; but i think i can do something for you now. go straight to the white house [that of a neighboring proprietor], and tell the folk there to set out with all the speed of man and horse for the black rock in the sea, at the foot of the crags, or they'll rue it dearly to their dying day. their bairns, foolish things, have gone out to the rock, and the tide has flowed around them; and, if no help reach them soon, they'll be all scattered like sea-ware on the shore ere the fall of the sea. but if you go and tell your story at the white house, mammie, the bairns will be safe for an hour to come, and there will be something done by their mother to better you, for the news." the woman went, as directed, and told her story; and the father of the children set out on horseback in hot haste for the rock,--a low, insulated skerry, which, lying on a solitary part of the beach, far below the line of flood, was shut out from the view of the inhabited country by a wall of precipices, and covered every tide by several feet of water. on reaching the edge of the cliffs, he saw the black rock, as the woman had described, surrounded by the sea, and the children clinging to its higher crags. but, though the waves were fast rising, his attempts to ride out through the surf to the poor little things were frustrated by their cries, which so frightened his horse as to render it unmanageable; and so he had to gallop on to the nearest fishing village for a boat. so much time was unavoidably lost in consequence, that nearly the whole beach was covered by the sea, and the surf had begun to lash the feet of the precipices behind; but until the boat arrived, not a single wave dashed over the black rock; though immediately after the last of the children had been rescued, an immense wreath of foam rose twice a man's height over its topmost pinnacle. the old nurse, on her return to the cottage, found the green lady sitting beside the fire. "mammie," she said, "you have made friends to yourself to-day, who will be kinder to you than your foster-son. i must now leave you. my time is out, and you'll be all left to yourselves; but i'll have no rest, mammie, for many a twelvemonth to come. ten years ago, a travelling peddler broke into our garden in the fruit season, and i sent out our old ploughman, who is now in ireland, to drive him away. it was on a sunday, and everybody else was in church. the men struggled and fought, and the peddler was killed. but though i at first thought of bringing the case before the laird, when i saw the dead man's pack, with its silks and its velvets, and this unhappy piece of green satin (shaking her dress), my foolish heart beguiled me, and i made the ploughman bury the peddler's body under our ash tree, in the corner of our garden, and we divided his goods and money between us. you must bid the laird raise his bones, and carry them to the churchyard; and the gold, which you will find in the little bowl under the tapestry in my room, must be sent to a poor old widow, the peddler's mother, who lives on the shore of leith. i must now away to ireland to the ploughman; and i'll be e'en less welcome to him, mammie, than at the laird's; but the hungry blood cries loud against us both,--him and me,--and we must suffer together. take care you look not after me till i have passed the knowe." she glided away, as she spoke, in a gleam of light; and when the old woman had withdrawn her hand from her eyes, dazzled by the sudden brightness, she saw only a large black gray-hound crossing the moor. and the green lady was never afterwards seen in scotland. the little hoard of gold pieces, however, stored in a concealed recess of her former apartment, and the mouldering ruins of the peddler under the ash tree, gave evidence to the truth of her narrative. the story was hardly wild enough for a night so drear and a road so lonely; its ghost-heroine was but a homely ghost-heroine, too little aware that the same familiarity which, according to the proverb, breeds contempt when exercised by the denizens of this world, produces similar effects when too much indulged in by the inhabitants of another. but the arrangement and restoration of the details of the tradition,--for they had been scattered in my mind like the fragments of a broken fossil,--furnished me with so much amusement, when struggling with the storm, as to shorten by at least one-half the seven miles which intervene between gamrie and macduff. instead, however, of pressing on to banff, as i had at first intended, i baited for the night at a snug little inn in the latter village, which i reached just wet enough to enjoy the luxury of a strong clear fire of newcastle coal. mrs. longmuir had furnished me with a note of introduction to dr. emslie of banff, an intelligent geologist, familiar with the deposits of the district; and, walking on to his place of residence next morning, in a rain as heavy as that of the previous night, i made it my first business to wait on him, and deliver the note. ere, however, crossing the deveron, which flows between banff and macduff, i paused for a few minutes in the rain, to mark the peculiar appearance presented by the beach where the river disembogues into the frith. occurring as a rectangular spit in the line of the shore, with the expanded stream widening into an estuary on its upper side, and the open sea on the lower, it marks the scene of an obstinate contest between antagonist forces,--the powerful sweep of the torrent, and the not less powerful waves of the stormy north-east; and exists, in consequence, as a long gravelly prism, which presents as steep an angle of descent to the waves on the one side as to the current on the other. it is a true river bar, beaten in from its proper place in the sea by the violence of the surf, and fairly stranded. dr. emslie obligingly submitted to my inspection his set of gamrie fossils, containing several good specimens of pterichthys and coccosteus, undistinguishable, like those i had seen on the previous day, in their state of keeping, and the character of the nodular matrices in which they lie, from my old acquaintance the cephalaspians of cromarty. the animal matter which the bony plates and scales originally contained has been converted, in both the gamrie and cromarty ichthyolites, into a jet-black bitumen; and in both, the inclosing nodules consist of a smoke-colored argillaceous limestone, which formed around the organisms in a bed of stratified clay, and at once exhibits, in consequence, the rectilinear lines of the stratification, mechanical in their origin, and the radiating ones of the sub-crystalline concretion, purely a trick of the chemistry of the deposit. a pterichthys in dr. emslie's collection struck me as different in its proportions from any i had previously seen, though, from its state of rather imperfect preservation, i hesitated to pronounce absolutely upon the fact. i cannot now doubt, however, that it belonged to a species not figured nor described at the time; but which, under the name of _pterichthys quadratus_, forms in part the subject of a still unpublished memoir, in which sir philip egerton, our first british authority on fossil fish, has done me the honor to associate my humble name with his own; and which will have the effect of reducing to the ranks of the pterichthyan genus the supposed genera _pamphractus_ and _homothorax_. a second set of fossils, which dr. emslie had derived from his tile-works at blackpots, proved, i found, identical with those of the eathie lias. as this banffshire deposit had formed a subject of considerable discussion and difference among geologists, i was curious to examine it; and the doctor, though the day was still none of the best, kindly walked out with me, to bring under my notice appearances which, in the haste of a first examination, i might possibly overlook, and to show me yet another set of fossils which he kept at the works. he informed me, as we went, that the grauwacke (lower silurian) deposits of the district, hitherto deemed so barren, had recently yielded their organisms in a slate quarry at gamrie-head; and that they belong to that ancient family of the pennatularia which, in this northern kingdom, seems to have taken precedence of all the others. judging from what now appears, the graptolite must be regarded as the first settler who squatted for a living in that deep-sea area of undefined boundary occupied at the present time by the bold wave-worn headlands and blue hills of scotland; and this new banffshire locality not only greatly extends the range of the fossil in reference to the kingdom, but also establishes, in a general way, the fossiliferous identity of the lower silurian deposits to the north of the grampians with that of peebles-shire and galloway in the south,--so far as i know, the only other two scottish districts in which this organism has been found. the argillaceous deposit of blackpots occupies, in the form of a green swelling bank, a promontory rather soft than bold in its contour, that projects far into the sea, and forms, when tipped with its slim column of smoke from the tile-kiln, a pleasing feature in the landscape. i had set it down on the previous day, when it first caught my eye from the lofty cliffs of gamrie-head, at the distance of some ten or twelve miles, as different in character from all the other features of the prospect. the country generally is moulded on a framework of primary rock, and presents headlands of hard, sharp outline, to the attrition of the waves; whereas this single headland in the midst,--soft-lined, undulatory, and plump,--seems suited to remind one of burns's young kirk alloway beauty disporting amid the thin old ladies that joined with her in the dance. and it _is_ a greatly younger beauty than the cambrian and mica-schist protuberances that encroach on the sea on either side of it. the sheds and kilns of a tile-work occupy the flat terminal point of the promontory; and as the clay is valuable, in this tile-draining age, for the facility with which it can be moulded into pipe-tiles (a purpose which the ordinary clays of the north of scotland, composed chiefly of re-formations of the old red sandstone, are what is technically termed too _short_ to serve), it is gradually retreating inland before the persevering spade and mattock of the laborer. the deposit has already been drawn out into many hundred miles of cylindrical pipes, and is destined to be drawn out into many thousands more,--such being one of the strange metamorphoses effected in the geologic formations, now that that curious animal the bimana has come upon the stage; and at length it will have no existence in the country, save as an immense system of veins and arteries underlying the vegetable mould. will these veins and arteries, i marvel, form, in their turn, the _fossils_ of another period, when a higher platform than that into which they have been laid will be occupied to the full by plants and animals specifically different from those of the present scene of things,--the existences of a happier and more finished creation? my business to-day, however, was with the fossils which the deposit now contains,--not with those which it may ultimately form. the blackpots clay is of a dark-bluish or greenish-gray color, and so adhesive, that i now felt, when walking among it, after the softening rains of the previous night and morning, as if i had got into a bed of bird-lime. it is thinly charged with rolled pebbles, septaria, and pieces of a bituminous shale, containing broken belemnites, and sorely-flattened ammonites, that exist as thin films of a white chalky lime. the pebbles, like those of the boulder-clay of the northern side of the moray frith, are chiefly of the primary rocks and older sandstones, and were probably in the neighborhood, in their present rolled form, long ere the re-formation of the inclosing mass; while the shale and the septaria are, as shown by their fossils, decidedly liasic. i detected among the conchifers a well-marked species of our northern lias, figured by sowerby from eathie specimens,--the _plagiostoma concentrica_; and among the cephalopoda, though considerably broken, the _belemnite elongatus_ and _belemnite lanceolata_, with the _ammonite koenigi_ (_mutabilis_),--all eathie shells. i, besides, found in the bank a piece of a peculiar-looking quartzose sandstone, traversed by hard jaspedeous veins of a brownish-gray color, which i have never found, in scotland at least, save associated with the lias of our north-eastern coasts. further, my attention was directed by dr. emslie to a fine lignite in his collection, which had once formed some eighteen inches or two feet of the trunk of a straight slender pine,--probably the _pinites eiggensis_,--in which, as in most woods of the lias and oölite, the annual rings are as strongly marked as in the existing firs or larches of our hill-sides.[ ] the blackpots deposit is evidently a re-formation of a liasic patch, identical, both in mineralogical character and in its organic remains, with the lower beds of the eathie lias; while the fragments of shale which it contains belong chiefly to an upper liasic bed. so rich is the dark-colored tenacious argil of the inferior lias of eathie, that the geologist who walks over it when it is still moist with the receding tide would do well to look to his footing;--the mixture of soap and grease spread by the ship-carpenter on his launch-slips, to facilitate the progress of his vessel seawards, is not more treacherous to the tread: while the upper liasic deposit which rests over it is composed of a dark slaty shale, largely charged with bitumen. and of a liasic deposit of this compound character, consisting in larger part of an inferior argillaceous bed, and in lesser part of a superior one of dark shale, the tile-clay of blackpots has been formed. i had next to determine whether aught remained to indicate the period of its re-formation. the tile-works at the point of the promontory rest on a bed of shell-sand, composed exclusively, like the sand so abundant on the western coast of scotland, of fragments of existing shells. these, however, are so fresh and firm, that, though the stratum which they form seems to underlie the clay at its edges, i cannot regard them as older than the most modern of our ancient sea-margins. they formed, in all probability, in the days of the old coast line, a white shelly beach, under such a precipitous front of the dark clay as argillaceous deposits almost always present to the undermining wear of the waves. on the recession of the sea, however, to its present line, the abrupt, steep front, loosened by the frosts and washed by the rains, would of course gradually moulder down over them into a slope; and there would thus be communicated to the shelly stratum, at least at its edges, an underlying character. the true period of the re-formation of the deposit was, i can have no doubt, that of the boulder-clay. i observed that the septaria and larger masses of shale which the bed contains, bear, on roughly-polished surfaces, in the line of their larger axes, the mysterious groovings and scratchings of this period,--marks which i have never yet known to fail in their chronological evidence. it may be mentioned, too, simply as a fact, though one of less value than the other, that the deposit occurs in its larger development exactly where, in the average, the boulder-clays also are most largely developed,--a little over that line where the waves for so many ages charged against the coast, ere the last upheaval of the land or the recession of the sea sent them back to their present margin. there had probably existed to the west or north-west of the deposit, perhaps in the middle of the open bay formed by the promontory on which it rests,--for the small proportion of other than liasic materials which it contains serves to show that it could be derived from no great distance,--an outlier of the lower lias. the icebergs of the cold glacial period, propelled along the submerged land by some arctic current, or caught up by the gulf-stream, gradually grated it down, as a mason's laborer grates down the surface of the sandstone slab which he is engaged in polishing; and the comminuted debris, borne eastwards by the current, was cast down here. it has been stated that no liasic remains have been found in the boulder-clays of scotland. they are certainly rare in the boulder-clays of the northern shores of the moray frith; for there the nearest lias, bearing in a western direction from the clay, is that of applecross, on the other side of the island; and the materials of the boulder-deposits of the north have invariably been derived in the line, westerly in its general bearing, of the grooves and scratches of the iceberg era. but on the southern shore of the frith, where that westerly line passed athwart the liasic beds of our eastern coast, organisms of the lias are comparatively common in the boulder-clays; and here, at blackpots, we find an extensive deposit of the same period formed of liasic materials almost exclusively. fragments of still more modern rocks occur in the boulder-clays of caithness. my friend mr. robert dick, of thurso, to whose persevering labors and interesting discoveries in the old red sandstone of his locality i have had frequent occasion to refer, has detected in a blue boulder-clay, scooped into precipitous banks by the river thorsa, fragments both of chalk-flints and a characteristic conglomerate of the oölite. he has, besides, found it mottled from top to bottom, a full hundred feet over the sea-level, and about two miles inland, with comminuted fragments of existing shells. but of this more anon. chapter iii. from blackpots to portsoy--character of the coast--burn of boyne--fever phantoms--graphic granite--maupertuis and the runic inscription--explanation of the _quo modo_ of graphic granite--portsoy inn--serpentine beds--portsoy serpentine unrivalled for small ornaments--description of it--significance of the term _serpentine_--elizabeth bond and her "letters"--from portsoy to cullen--attritive power of the ocean illustrated--the equinoctial--from cullen to fochabers--the old red again--the old pensioner--fochabers--mr. joss, the learned mail-guard--the editor a sort of coach-guard--on the coach to elgin--geology of banffshire--irregular paging of the geologic leaves--geologic map of the county like joseph's coat--striking illustration. i parted from dr. emslie, and walked on along the shore to portsoy,--for three-fourths of the way over the prevailing grauwacke of the county, and for the remaining fourth over mica schist, primary limestone, hornblende slate, granitic and quartz veins, and the various other kindred rocks of a primary district. the day was still gloomy and gray, and ill suited to improve homely scenery; nor is this portion of the banff coast nearly so striking as that which i had travelled over the day before. it has, however, its spots of a redeeming character,--rocky recesses on the shore, half-beach, half-sward, rich in wild-flowers and shells,--where one could saunter in a calm sunny morning, with one's _bairns_ about one, very delightfully; and the interior is here and there agreeably undulated by diluvial hillocks, that, when the sun falls low in the evening, must chequer the landscape with many a pleasing alternation of light and shadow. the burn of boyne,--which separates, about two miles from portsoy, a grauwacke from a mica-schist district,--with its bare, open valley, its steep limestone banks, and its gray, melancholy castle, long since roofless and windowless, and surrounded by a few stunted trees, bears a deserted and solitary shagginess about it, that struck me as wildly agreeable. it is such a valley as one might expect to meet a ghost in, in some still, dewy evening, as gloamin was darkening into uncertainty the outlines of the ancient ruin, and the newly-kindled stars looked down upon the stream. it so happened, however, that my only story connected with either ruin or valley was as little a ghost story as might be. i remember that, when lying ill of fever on one occasion,--indisposed enough to see apparition after apparition flitting across the bed-curtains, like the figures of a magic lantern posting along the darkened wall, and yet self-possessed enough to know that they were but mere pictures in the eye, and to watch them as they rose,--i set myself to determine whether they were in any degree amenable to the will, or connected by the ordinary associative links of the metaphysician. fixing my mind on a certain object, i strove to call it up in the character, not of an image of the conceptive faculty, but of a fever-vision on the retina. the image which i pictured to myself was that of a death's head, yellow and grim, and lighted up, as if from within, amid the darkness of a burial vault. but the death's head obstinately refused to rise. i had no control, i found, over the fever imagery. and the picture that rose instead, uncalled and unexpected, was that of a coal-fire burning brightly in a grate, with a huge tea-kettle steaming cheerily over it. in traversing the bare height which, rising on the western side of the valley of the boyne, owes its comparatively bold relief in the landscape to the firmness of the primary rock which composes it, i picked up a piece of graphic granite, bearing its inlaid characters of dark quartz on a ground of cream-colored feldspar. this variety, however, though occasionally found in rolled boulders in the neighborhood of portsoy, is not the graphic granite for which the locality is famous, and which occurs in a vein in the mica schist of the eminence i was now traversing, about a mile to the east of the town. the prevailing ground of the granite of the vein is a flesh-colored feldspar; and the thickly-marked quartzose characters with which it is set, greatly smaller and paler than in the cream-colored stone, bear less the antique hebraic look, and would scarce deceive even the most credulous antiquary. antiquarians, however, _have_ been sometimes deceived by weathered specimens of this graphic rock, in which the characters were of considerable size, and restricted to thin veins, covering the surface of a schistose groundwork. maupertuis, during his famous journey to lapland, undertaken in , to establish, from actual measurement, that the degrees of latitude are longer towards the pole than at the equator, and which demonstrated, of consequence, the true figure of the earth, travelled thirty leagues out of his way, through a wild country covered with snow, to examine an ancient monument, of which, he says, "the fins and laplanders frequently spoke, as containing in its inscription the knowledge of everything of which they were ignorant." he found it on the side of a mountain, buried in snow; and ascertained, after kindling a great fire around it, in order to lay it bare, that it was a stone of irregular form, composed of various layers of unequal hardness, and that the characters, which were rather more than an inch in length, were written on "a layer of a species of flint," chiefly in two lines, with a few scattered signs beneath, while the rest of the mass was composed of a rock more soft and foliated. graphic granite, it may be mentioned, generally occurs, not in masses, but in veins and layers. the inscription had been described in a previously published dissertation of immense erudition, as runic; but a runic scholar of the party found he could make nothing of it. the philosopher himself was struck by the frequent repetition of characters of nearly the same form on the stone; but he was ingenious enough to get over the difficulty, by remembering that in our notation, after the arabic manner, characters shaped exactly alike may be very frequently repeated,--nay, as in some of the lines of the lapland inscription, may succeed each other, as in the sums i. ii. iii. iiii. or x. xx. xxx.,--and yet very distinct and definite ideas attach to them all. still, however, he could not, he says, venture on authoritatively deciding whether the inscription was a work of man or a sport of nature. he stood between his two conclusions, like our edinburgh antiquarians between the two fossil maries of gueldres; and, richer in eloquence than most of the philosophers his contemporaries, was quite prepared, in his uncertainty, to give gilded mounting and a purple pall to both. "should it be no other than a sport of nature," he concludes, "the reputation which the stone bears in this country deserves that we should have given a description of it. if, on the other hand, what is on it be an inscription, though it certainly does not possess the beauty of the sculpture of greece or rome, it very possibly has the advantage of being the oldest in the universe. the country in which it is found is inhabited only by a race of men who live like beasts in the forests. we cannot imagine that they can have ever had any memorable event to transmit to posterity, nor, if ever they had had, that they could have invented the means. nor can it be conceived that this country, with its present aspect, ever possessed more civilized inhabitants. the rigor of the climate and the barrenness of the land have destined it for the retreat of a few miserable wretches, who know no other. it seems, therefore, that the inscription must have been cut at a period when the country was situated in a different climate, and before some one of those great revolutions which, we cannot doubt, have taken place on our globe. the position that the earth's axis holds at present with respect to the ecliptic, occasions lapland to receive the sun's rays very obliquely: it is therefore condemned to a long winter, adverse to man, as well as to all the productions of nature. no great movement, possibly, in the heavens was necessary, however, to cause all its misfortunes. these regions may formerly have been those on which the sun shone most favorably; the polar circles may have been what now the tropics are, and the torrid zone have filled the place occupied by the temperate." pretty well, monsieur, for a philosopher! the various attempts made to unriddle the real history of graphic granite are, however, scarce less curious than the speculations connected with what may be termed its romance. it seems to be generally held, since the days of old hutton, who, in his "theory of the earth," discussed the subject with his usual ingenuity, that the feldspathic basis of the stone first crystallized, leaving interstices between the crystals, partaking of a certain regularity of form,--a consequence of the regularity of the crystals themselves,--and of a certain irregularity from the eccentric dispositions which these manifest in their position and relations to each other; and that these interstices, being afterwards filled up with quartz, form the characters of the rock,--characters partaking enough of the first element of _regularity_ to present their peculiar graphic appearance, and enough of the second element of _irregularity_ to exhibit forms of an alphabet-like variety of outline. the chemist, however, in cross-questioning the explanation, has his puzzle to propound regarding it. quartz, he says, being considerably less fusible than feldspar, would naturally consolidate first, and so would give form to the more fusible substance, instead of deriving form from it. on what principle, then, is it that, reversing its ordinary character, it should have been the last of the two substances to consolidate in the graphic granite?--a query to which there seems to be no direct reply, but which as little affects the fact that it _was_ the substance which last consolidated, and which took form from the other, as the decision of the learned strasburgers, which determined the impossibility of the long nose in slawkenbergius's tale, affected the actual existence of that remarkable feature. "it happens _to be_, notwithstanding your objection," said the controversialists on the pro-nose side of the question. "but it _ought not_," replied their opponents. the rain again returned as i was engaged in examining the graphic granite of the portsoy vein; the breeze from the sea heightened into a gale, that soon fringed the coast with a broad border of foam; and i entered the town, which looked but indifferently well in its gray dishabille of haze and spray, tolerably wet and worn, with but the prospect before me of being weather-bound for the rest of the day. i found an old-fashioned inn, kept by somewhat old-fashioned people, who had lately come from the country to "open a public;" and ensconced myself by the fireside, in a huge many-windowed room, that must have witnessed the county dinners of at least a century ago. soon wearying, however, of hearing the rain beating mad-like ratans upon the panes, and availing myself of a comparatively "lucid interval," i sallied out, wrapped up in my plaid, to examine the serpentine beds in the neighborhood, which produce what is so extensively known as the portsoy marble. the _beds_ or _veins_ of this substance,--for it is still a moot point whether they occur here as mere insulated masses of contemporary origin with the primary formations which surround them, or as plutonic dykes injected into fissures at a later period,--are of very considerable extent, one of them measuring about twenty-five yards across, and another considerably more than a quarter of a mile; and, had they but the solidity of the true marbles, they would scarce fail to be regarded as valuable quarries of a highly ornamental stone, admirably suited for the interior decorations of the architect. but they are unluckily what the quarrier would term rubbly,--traversed by an infinity of cracks and fissures; and it is rare indeed to find a continuous mass out of which a chimney-jamb or lintel could be fashioned. the serpentine was wrought here considerably more than a century and a half ago, and exported to france for the magnificent palace of versailles; which, though regarded by the french nation, says voltaire, as "a favorite without merit," louis the fourteenth persisted at the time in lavishly beautifying, and looked as for abroad as portsoy for materials with which to adorn it. i have, however, seen it stated that the greater part of a ship's cargo, brought afterwards to paris on speculation, was suffered to lie unwrought for years in the stone-dealer's yard, and was ultimately disposed of as rubbish,--a consequence, probably, of its unfitness, from its shaky texture, for ornamental purposes on a large scale, though for ornaments of the smaller kind, such as boxes, vases, and plates, it has been pronounced unrivalled. "at zöblitz, in upper saxony," says professor jamieson, "several hundred people are employed in quarrying, cutting, turning, and polishing the serpentine which occurs in that neighborhood; and the various articles into which it is manufactured are carried all over germany. the serpentine of portsoy," he adds, "is, however, far superior to that of zöblitz, in color, hardness, and transparency, and, when cut, is very beautiful." it is really a pretty stone; and, bad as the evening was, it was by no means one of the worst of evenings for seeing it to advantage _in situ_, or among the rolled pebbles on the shore. the varnish-like gloss of the wet imparted to the undressed masses all the effect of polish, and brought out in their proper variegations of color, every cloud, streak, and vein. viewed in the mass, the general hue is green; so much so, that an insulated stack, which stands abreast of one of the beds, a stone-cast in the sea, has greatly the appearance, at a little distance, of an immense mass of verdigris. but red, gray, and brown are also prevailing colors in the rock; occasional veins and blotches of white give lightness to the darker portions; and veins of hematitic and deep umbry tints, variety to the portions that are lighter. the greens vary from the palest olive to the deepest black-green of the mineralogist; the reds and browns, from blood-red to dark chocolate, and from wood-brown to brownish-black; and, thus various in shade, they occur in almost every possible variety of combination and form,--dotted, spotted, clouded, veined,--so that each separate pebble on the shore seems the representative of a rock different from the rocks represented by almost all the others. though not much of a mineralogist, i could have spent considerably more time than the weather permitted me to employ this evening, in admiring the beauties of this beach of _marbles_, or rather,--as the real name, derived from those gorgeous, many-colored cloudings, that impart a terrible splendor to the skins of the snake and viper family, is not only the more correct, but also the more poetical of the two,--this beach of _serpentines_. i had, however, to compromise matters between the fierce wind and rain and the pretty rocks and pebbles, by adjourning to the workshop of the portsoy lapidary, mr. clark, and examining under cover his polished specimens, of which i purchased for a few shillings a characteristic and elegant little set. portsoy is peculiarly rich in minerals; and hence it reckons among its mechanics of the ordinary class, what perhaps no other village in scotland of the same size and population possesses,--a skilful lapidary. mr. clark's collection of the graphic granites, serpentines, and talcose and mica schists, of the district, with their associated minerals, such as schorl, talc, asbestos, amianthus, mountain cork, steatite, and schiller spar, will be found eminently worthy a visit by the passing traveller. i made several inquiries in the village, though not, as it proved, in the right direction, regarding a poor old lady, several years dead, of whom i had known a very little considerably more than a quarter of a century before, and whose grave i would have visited, bad as the night was, had i met any one who could have pointed it out to me. but ungrateful portsoy seemed to have forgotten poor miss bond, who, in all her printed letters and little stories, so rarely forgot _it_. have any of my readers ever seen the work (in two slim volumes), "letters of a village governess," published in by elizabeth bond, and dedicated to sir walter scott? if not, and should they chance to see, as i lately did, a copy on a stall (with uncut leaves, alas! and selling dog cheap), they might possibly do worse things than buy it.[ ] with better weather i could have spent a day or two very agreeably in portsoy and its neighborhood; but the rain dashed unceasingly, and made exploration under the cover of the umbrella somewhat resemble that of a sea-bottom under cover of the diving-bell. i could see but little at a time, and the little imperfectly. miss bond, in her "letters," refers, in her light, pleasing style, to what in more favorable circumstances _might_ be seen. "my troop of _light infantry_," she says, "keeps me so well employed here during the day, that the silence and repose of the evening is very delightful. in fine weather i walk by the sea-side, and scramble among the rugged rocks, many of which are inaccessible to human feet, forming a fine retreat for foxes. these animals often may be seen from the heights, sporting with their cubs in perfect safety. this day i went to see the works of an old _virtuoso_, who turns in marble, or rather granite [serpentine] all kinds of chimney-piece ornaments, rings, ear-rings, etc. several specimens of his work, which must have cost him a vast deal of trouble, i thought very beautiful. it was in this neighborhood that the celebrated ferguson spent so much of his time. the globular stones on the gate of durn are still to be seen, on which he mapped out the figuring of the terrestrial and celestial globes. i was told it was forbidden ground to approach the premises of durn; but i could not resist the temptation of visiting the spot where the young philosopher had shown such early proofs of his genius; and i accordingly paid the forfeit of an _impertinent_, for the gentleman who resides there caught the prowler, and in genteel terms bade her go about her business, and never return. how ungracious! she was doing no harm." the morning arose as gloomily as the evening had fallen; and i walked on in the rain to cullen, fully disposed to sympathize by the way with the "hardy byron,"--he of the "narrative,"--who, from his ill-luck in weather, went among his sailors by the name of "foul-weather jack." in the sandy bay of cullen, where the road, after inflecting inland for some five or six miles, comes again upon the sea, i found the surf charging home in long white lines six waves deep,-- "each stepping where his comrade stood, the instant that he fell." the appearance was such as to impart no inadequate idea of the vast attritive power of ocean in wearing down the land. when pausing for a little abreast of the fishing village, partially sheltered by an old boat, to mark the fierce turmoil, it suddenly occurred to me,--as the tempest weltered around reef and skerry, and roared wildly, mile after mile, along the beach,--that the day and night were now just equal, and that it was the customary equinoctial storm that had broken out to accompany me on my journey. and so, calculating on a few days more of it, instead of waiting on in the hope of a fair afternoon to examine the outlier of old red which occurs in the neighborhood of cullen, i was content to see at a distance its mural-sided cliffs rising like broken walls through the flat sand; and, taking the road for fochabers, with the intention of leaving exploration till fairer weather set in, i resolved on posting straight on, to join my relatives on the opposite side of the frith. the deep-red color of the boulder-clay, as exhibited by the way-side, in the water-courses and the water,--for every runnel was tumbling down big and turbid with the rains,--intimated, when, after leaving cullen some six or seven miles behind me, i passed from a bare moory region of quartz rock into a region of woods and fields, that i was again upon my ancient acquaintance, the old red sandstone. and the section furnished by the burn of tynet showed me shortly after that the intimation was a correct one, and how generally it may be laid down as a rule, that at least the more impalpable portions of the boulder-clay are derived from the rocks on which it rests. the ichthyolite beds appear in the course of the burn. they have furnished several good specimens,--among the others, the specimen of coccosteus figured by mr. patrick duff in his "sketches of the geology of moray;" and they are, besides, curious, as being the first to exhibit to the traveller who explores from gamrie westwards, that peculiar style of coloring which characterizes the old red ichthyolites of the shires of moray and nairn, and which differs so strikingly from the more sombre style exhibited by the other ichthyolites of banffshire, with those of cromarty, ross, caithness, and orkney. instead of bearing, like these, one uniform hue, as if deeply shaded with indian ink, they are gorgeously attired, especially when newly laid open, in white, red, purple, and blue. the day, however, was ill-suited for fishing pterichthyes and osteolepi out of the tynet: the red water was roaring from bank to brae; here eddying along the half-submerged furze,--there tearing down the boulder-days in raw, red land-slips; and so, casting but one eager glance at the bed where the fish lay, i travelled on, and entered the tall woods to the east of fochabers. the rain ceased for a time; and i met in the woods an old pensioner, who had been evidently weather-bound in some public-house, and had now taken the opportunity of the fair interval to stagger to his dwelling. he was eminently, exuberantly happy,--there could not be two opinions on that head,--full of all manner of bright sunshiny thoughts and imaginations, rendered just a little tremulous and uncertain by the _summer-heat_ exhalations of the imbibed moisture, like distant objects in a hot noonday landscape in july seen through volumes of rising vapor; and a sheep's head and trotters, which he carried under his arm, was, i saw, to serve as a peace-offering to his wife at home. true, he had been taking a dram, but he was mindful of the family for all that. he confronted me with the air of an old acquaintance; gave the military salute; and then, laying hold of a corner of my plaid with his thumb and forefinger,--"i know you," he said, "i know _your kind_ well; ye're a highland-donald. od, i've seen ye in the _thick o't_. ye're _reugh_ fellows when ye're bluid's up!" he had taken me for a grenadier of the d; and i lacked the moral courage to undeceive him. i met nothing further on my way worthy of record, save and except a sheep's trotter, dropped by the old pensioner in one of his zig-zaggings to the extreme left; but having no particular use for the trotter at the time and in the circumstances, i left it to benefit the next passer-by. i finished my journey of eighteen miles in capital style, and was within five minutes' walk of fochabers when the horn of the mail-guard was sounding up the street. and, entering the village, i found the vehicle standing opposite the inn door, minus the horses. the _insides_ and _outsides_ were sitting down to dinner together as i entered the inn; and i felt, after my long walk, that it would be rather an agreeable matter to join with them. but in the hope of meeting my old friend mr. joss, i requested to be shown, not into the passengers' room, but into that of the coachman and guard; and with them i dined. it so chanced, however, that mr. joss was not _out_ that day; and the man in the red long coat was a stranger whom i had never seen before. i inquired of him regarding mr. joss,--one of perhaps the most remarkable mail-guards in europe. i have at least never heard of another who, like him, amuses his leisure on the coach-top with the "principia" of newton, and understands it. and the man, drawing his inference from the interest in mr. joss which my queries evinced, asked me whether i myself was not a coach-guard. "no," i rather thoughtlessly replied, "i am not a coach-guard." half a minute's consideration, however, led me to doubt whether i had given the right answer. "i am not sure," i said to myself, on second thoughts, "but the man has cut pretty fairly on the point;--i daresay _i am_ a sort of coach-guard. i have to mount my twice-a-week coach in all weathers, like any mail-guard among them all; i have to start at the appointed hour, whether the vehicle be empty or full; i have to keep a sharp eye on the opposition coaches; i am responsible, like any other mail-guard, for all the parcels carried, however little i may have had to do with the making of them up; i have always to keep my blunderbuss full charged to the muzzle,--not wishing harm to any one, but bound in duty to let drive at all and sundry who would make war upon the passengers, or attempt running the conveyance off the road; and, finally, as my friend mr. joss takes the "principia" to _his_ coach-top, i take pockets full of fossils to the top of mine, and amuse myself in fine days by working out, as i best can, the problems which they furnish. yes, i rather think _i am_ a coach-guard." and so, taking my seat beside my red-coated brother, who had guessed the true nature of my occupation so much more shrewdly than myself, i rode on to elgin, where i passed the night. it is difficult to arrange in the mind the geologic formations of banffshire in their character as a series of deposits. the pages of the stony record which the county composes, like those of an unskilfully-folded pamphlet, have been strangely mixed together, so that page last succeeds in some places to page first, and, of the intermediate pages, some appear at the beginning of the work, and some at the end. it is not until we reach the western confines of the county, some two or three miles short of the river spey, its terminal boundary in this direction, that we find the beds comparatively little disturbed, and arranged chronologically in their original places. in the eastern and southern parts of the shire, rocks widely separated by the date of their formation have been set down side by side in patches, occasionally of but inconsiderable extent. now the traveller passes over a district of grauwacke, now over a re-formation of the lias; anon he finds himself on a primary limestone,--gneiss, syenite, clay-slate, or quartz-rock; and yet anon amid the fossils of some outlier of the old red. the geological map of the county is, like joseph's coat, of many colors. i remember seeing, when a boy, more years ago than i am inclined to specify, some workmen engaged in pulling down what had been a house-painter's shop, a full century before. the painter had been in the somewhat slovenly habit of cleaning his brushes by rubbing them against a hard-cast wall, which was covered, in consequence, by a many-colored layer of paint, a full half-inch in thickness, and as hard as a stone. taking a little bit home with me, i polished it by rubbing the upper surface smooth; and, lo! a geological map. the _strata_ of variously hued pigment, spread originally over the surface of the hard-cast wall, were cut open, by the _denudation_ of the grindstone, into all manner of fantastic forms, and seemed thrown into all sorts of strange neighborhoods. the _map_ lacked merely the additional perplexity of a few bold _faults_, with here and there a decided _dike_, in order to render it on a small scale a sort of miniature transcript of the geology of banff; and i have very frequently found my thoughts reverting to it, in connection with deposits of this broken character. on a rough _hard-cast_ basis of granite i have laid down in imagination, as if by way of priming, coat after coat of the primary rocks,--gneiss, and stratified hornblend, and mica-schist, and quartz-rock, and day-slate; and then, after breaking the coatings well up, and rubbing them well down, and so spoiling and crumpling up the work as to make their original order considerably a puzzle, i have begun anew to paint over the rough surface with thick coatings of grauwacke and grauwacke-slate. when this part of the operation was completed, i have again begun to break up and grind down,--here letting a tract of grauwacke sink into the broken primary,--there wearing it off the surface altogether,--yonder elevating the original granitic _hard-cast_ till it rose over all the coatings, primary and palæozoic. and then i have begun to paint yet a third time with thick old red sandstone pigment; and yet again to break up and wear down,--here to insert a tenon of the old red deep into a mortise of the grauwacke, as at gamrie,--there to dovetail it into the clay-slate, as at tomantoul,--yonder, after laying it across the upturned quartz-rock, as at cullen, to rub by much the greater part of it away again, leaving but mere remainder-patches and fragments, to mark where it had been. lastly, if i had none of the superior palæozoic or secondary formations to deal with, i have brushed over the whole, by way of finish, with the variously-derived coatings of the superficial deposits; and thus, as i have said, i have often completed, in idea, after the chance suggestion of the old painter's shop, my portable models of the geology of disturbed districts like the banffshire one. the deposits of moray are greatly less broken. denudation has partially worn them down; but they seem to have almost wholly escaped the previous crumpling process. chapter iv. yellow-hued houses of elgin--geology of the country indicated by the coloring of the stone houses--fossils of old red north of the grampians different from those of old red south--geologic formations at linksfield difficult to be understood--ganoid scales of the wealden--sudden reaction, from complex to simple, in the scales of fishes--pore-covered scales--extraordinary amount of design exhibited in ancient ganoid scales--holoptychius scale illustrated by cromwell's "fluted pot"--patrick duff's geological collection--elgin museum--fishes of the ganges--armature of ancient fishes--compensatory defences--the hermit-crab--spines of the pimelodi--ride to campbelton--theories of the formation of ardersier and fortrose promontories--tradition of their construction by the wizard, michael scott--a region of legendary lore. the prevailing yellow hue of the elgin houses strikes the eye of the geologist who has travelled northwards from the frith of forth. he takes leave of a similar stone at cupar-fife,--a warmly-tinted yellow sandstone, peculiarly well-suited for giving effect to architectural ornament; and after passing along the deep-red sandstone houses of the shires of angus and kincardine, and the gneiss, granite, hyperstene, and mica-schist houses of aberdeen and banff shires, he again finds houses of a deep red on crossing the spey, and houses of a warm yellow tint on reaching elgin,--geologically the cupar-fife of the north. and the story that the colored buildings tell him is, that he has been passing, though by a somewhat circuitous route of a hundred and fifty miles, over an anticlinal geological section,--_down_ in the scale till he reached aberdeen and had gone a little beyond it, and then _up_ again, until at elgin he arrives at the same superior yellow bed of old red sandstone which he had quitted at cupar-fife. both beds contain the same organisms. the holoptychius of dura den, near cupar, must have sprung from the same original as the holoptychius of the hospital and bishop-mill quarries near elgin; and it seems not improbable that the two beds, thus identical in their character and contents, may have existed, ere the upheaval of the grampians broke their continuity, as an extended deposit, at the bottom of the same sea. but with this last and newest of the formations of the old red sandstone the identity of the deposits to the south and north ceases. the strata which in the south overlie the yellow bed of the holoptychius represent the carboniferous period, the overlying strata in the north represent the oölitic one. on the one side the miner sinks his shaft, and finds a true coal, composed of the stigmaria, calamites, club-mosses, ferns, and araucarians of the palæozoic era; he sinks his shaft on the other side, and finds but thin seams of an imperfect lignite, composed of the cycadeæ, pines, sphenopteri, and clathraria of the secondary period. the flora which found its subsoil in the old red sandstone north of the grampians, belonged to a scene of things so much more modern than the flora which found its subsoil in the old red sandstone of the south, that all its productions were green and flourishing, waving beside lake, river, and sea, at a time when the productions of the other were locked up, as now, in sand and shale, lime and clay,--the dead mummies of ages long departed. another thoroughly wet morning! varied only from the morning of the preceding day by the absence of wind, and the greater weight of the persevering vertical rain, that leaped upwards in myriads of little dancing pyramids from the surface of every pool. i walked out under cover of my umbrella, to renew my acquaintance with the outlier of the weald at linksfield, and ascertain what sort of section it now presented under the quarrying operations of the limeburners. there was, however, little to be seen; the bands of green and blue clays, alternating with strata of fossiliferous limestone, and layers of a gray shade, thickly charged with minute shells of cypris, were sadly blurred this morning by the trail of numerous slips from above, which had fallen during the rains, and softened into mud as they rushed downwards athwart the face of the quarry: and the arched band of boulder-clay which so mysteriously underlies the deposit was, save in a few parts, wholly covered up by the debris. the occurrence of the clay here as an inferior bed, with but the cornstone of the old red beneath, and all the beds of the weald resting over it, forms a riddle somewhat difficult of solution; but it is palpably not reading it aright to regard the deposit, with at least one geologist who has written on the subject, as older than the rocks above. it is, on the contrary, as a vast amount of various and unequivocal evidence demonstrates, incalculably more modern; nay, we find proof of the fact here in that very bed which has been instanced as rendering it doubtful; the clay of which the interpolation is composed is found to contain fragments, not only of the cornstone on which it rests, but also of the wealden limestone and shales which it underlies. it forms the mere filling up of a flat-roofed cavern, or rather of two flat-roofed caverns,--for the limestone roof dipped in the centre to the cornstone floor,--which, previous to the times of the boulder-clay, had lain open in what was then, as now, an old-world deposit, charged with long extinct organisms, but which, during the iceberg period, was penetrated and occupied by the clay, as run lime penetrates and occupies the interstices of a dry-stone wall. it was no day for gathering fossils. i saw a few ganoid scales, washed by the rain from the investing rubbish, glittering on fragments of the limestone, with a few of the characteristic shells of the deposit, chiefly unionidæ; but nothing worth bringing away. the adhesive clay of the weald, widely scattered by the workmen, and wrought into mortar by the beating rains, made it a matter of some difficulty for the struggling foot to retain the shoe, and, sticking to my soles by pounds at a time, rendered me obnoxious to the old english nickname of "rough-footed scot." and so, after traversing the heaps, somewhat like a fly in treacle, i had to yield to the rain above and the mud beneath, and to return to do in elgin what cannot be done equally well in almost any other town of its size in scotland,--pursue my geological inquiries under cover. on this, as on other occasions, i was struck by the complex and very various forms assumed by the ganoid scales of the wealden. throughout the oölitic system generally, including the lias, there obtains a singular complexity of type in these little glittering tiles of enamelled bone, which contrasts strongly with the greatly more simple style which obtained among the ganoids of the palæozoic period. in many of these last, as in the coelacanth family, including the genera holoptychius, asterolepis, and glyptolepis, in all their many species, with at least one genus of dipterians, the genus dipterus, the external outline and arrangement of scale was as simple as in any of the cycloid family of the present time. like slates on a roof, each single scale covered two, and was covered by two in turn; and the only point of difference which existed in relation to the _laying down_ of these massy _slates_ of _bone_, and the laying down of the very thin ones of _horn_ which cover fish such as the carp or salmon, was, that in the massier _slates_, the sides, or _cover_,--nicely bevelled, in order to preserve an equability of thickness throughout,--were so adjusted, that two scales at their edges, where they lay the one over the other, were not thicker than one scale at its centre. even in the other ganoids, their contemporaries, such as the osteolepis and diplopterus, where the scales were ranged more in the tile fashion, side by side, there was, with much ingenious carpentry in the fitting, a general simplicity of form. it would almost appear, however, that ere the ganoid order reached the times of the weald, the simple forms had been exhausted, and that nature, abhorring repetition, and ever stamping upon the scales some specific characteristic of the creature that bore them, was obliged to have recourse to forms of a more complex and involved outline. these latter-day scales send out nail-like spikes laterally and atop, to lay hold upon their neighbors, and exhibit in their undersides grooves that accommodated the nails sent out, in turn, by their neighbors, to lay hold upon _them_. their forms, too, are indescribably various and fantastic. it seems curious enough, that immediately after this extremely _artificial_ state of things, if i may so speak, the two prevailing orders of the fish of the present day, the cycloids and ctenoids, should have been ushered upon the scene, and more than the original simplicity of scale restored. there took place a sudden reäction, from the fantastic and the complex to the simple and the plain. it is further worthy of notice, that though many of the ganoid scales of the secondary systems, including those of the wealden, glitter as brightly in burnished enamel as the more splendent scales of the old red sandstone and coal measures, there is a curious peculiarity exhibited in the structure of many of the older scales of the highly enamelled class, which, so far as i have yet seen, does not extend beyond the palæozoic period. the outer layer of the scale, which lies over a middle layer of a cellular cancellated structure, and corresponds, apparently, with that scarf-skin which in the human subject overlies the _rete mucosum_, is thickly set over with microscopic pores, funnel-shaped in the transverse section, and which, examined by a good glass, in the horizontal one resemble the puncturings of a sieve. the megalichthys of the coal measures, with its various carboniferous congeners, with the genera diplopterus, dipterus, and osteolepis of the old red sandstone,--all brilliantly enamelled fish,--are thickly pore-covered. but whatever purpose these pores may have served, it seems in the secondary period to have been otherwise accomplished, if, indeed, it continued to exist. it is a curious circumstance, that in no case do the pores seem to pass _through_ the scale. whatever their use, they existed merely as communications between the cells of the middle cancellated layer and the surface. in a fish of the chalk,--_macropoma mantelli_,--the exposed fields of the scales are covered over with apparently hollow, elongated cylinders, as the little tubes in a shower-bath cover their round field of tin, save that they lie in a greatly flatter angle than the tubes; but i know not that, like the pores of the dipterians and the megalichthys, they communicated between the interior of the scale and its external surface. their structure is at any rate palpably different, and they bear no such resemblance to the pores of the human skin as that which the palæozoic pores present. the amount of design exhibited in the scales of some of the more ancient ganoids,--design obvious enough to be clearly read,--is very extraordinary. a single scale of _holoptychius nobilissimus_,--fast locked up in its red sandstone rock,--laid by, as it were, for ever,--will be seen, if we but set ourselves to unravel its texture, to form such an instance of nice adaptation of means to an end as might of itself be sufficient to confound the atheist. let me attempt placing one of these scales before the reader, in its character as a flat counter of bone, of a nearly circular form, an inch and a half in diameter, and an eighth-part of an inch in thickness; and then ask him to bethink himself of the various means by which he would impart to it the greatest possible degree of strength. the human skull consists of two tables of solid bone, an inner and an outer, with a spongy cellular substance interposed between them, termed the _diploe_; and such is the effect of this arrangement, that the blow which would fracture a continuous wall of bone has its force broken by the spongy intermediate layer, and merely injures the outer table, leaving not unfrequently the inner one, which more especially protects the brain, wholly unharmed. now, such also was the arrangement in the scale of the _holoptychius nobilissimus_. it consisted of its two well-marked tables of solid bone, corresponding in their dermal character, the outer to the cuticle, the inner to the true skin, and the intermediate cellular layer to the _rete mucosum_; but bearing an unmistakable analogy also, as a mechanical contrivance, to the two plates and the _diploe_ of the human skull. to the strengthening principle of the two tables, however, there were two other principles added. cromwell, when commissioning for a new helmet, his old one being, as he expresses it, "ill set," ordered his friend to send him a "_fluted pot_," _i.e._, a helmet ridged and furrowed on the surface, and suited to break, by its protuberant lines, the force of a blow, so that the vibrations of the stroke would reach the body of the metal deadened and flat. now, the outer table of the scale of the holoptychius was a "fluted pot." the alternate ridges and furrows which ornamented its surface served a purpose exactly similar with that of the flutes and fillets of cromwell's helmet. the inner table was strengthened on a different but not less effective principle. the human stomach consists of three coats; and two of these, the outermost or peritoneal coat, and the middle or muscular coat, are so arranged, that the fibres of the one cross at nearly right angles those of the other. the violence which would tear the compact sides of this important organ along the fibres of the outer coat, would be checked by the transverse arrangement of the fibres of the middle coat, and _vice versa_. we find the cotton manufacturer weaving some of his stronger fabrics on a similar plan;--they also are made to consist of two _coats_; and what is technically termed the _tear_ of the upper is so disposed that it lies at an angle of forty-five degrees with the _tear_ of the coat which lies underneath. now, the inner table of the scale of the holoptychius was composed, on this principle, of various layers or coats, arranged the one over the other, so that the fibres of each lay at right angles with the fibres of the others in immediate contact with it. in the inner table of one scale i reckon nine of these alternating, variously-disposed layers; so that any application of violence, which, in the language of the lath-splitter, would _run lengthwise along the grain_ of four of them, would be checked by the _cross grain_ in five. in other words, the line of the _tear_ in five of the layers was ranged at right angles with the line of the _tear_ in four. there were thus in a single scale, in order to secure the greatest possible amount of strength,--and who can say what other purposes may have been secured besides?--three distinct principles embodied,--the principle of the two tables and _diploe_ of the human skull,--the principle of the variously arranged coats of the human stomach,--and the principle of oliver cromwell's "fluted pot." there have been elaborate treatises written on those ornate flooring-tiles of the classical and middle ages, that are occasionally dug up by the antiquary amid monastic ruins, or on the sites of old roman stations. but did any of them ever tell a story half so instructive or so strange as that told by the incalculably more ancient ganoid _tiles_ of the palæozoic and secondary periods? i called, on my way back from linksfield, upon my old friend mr. patrick duff, and was introduced once more to his exquisite collection, with its unique ichthyolites of at least two genera of fishes of the old red,--the _stagonolepis_ and _placothorax_ of agassiz,--which up to the present time are to be seen nowhere else; and various other fine specimens of rare species, which, having sat for their portraits, have their forms preserved in the great work of the naturalist of neufchatel. he showed me, with some triumph, one of his later acquisitions,--a fine specimen of holoptychius from the upper yellow sandstone of bishop-mill, which exhibits the dorsal ridge covered with a line of large overlapping scales, not at all unlike those overlapping plates which cover the tail of the lobster; for which, by the way, they were mistaken by the workman who first laid the fossil open. i examined, too, with some interest, fragments of a gigantic species of pterichthys, belonging to an inferior division of the same upper old red formation as the yellow stone, designated by agassiz _pterichthys major_, which must have attained to at least thrice the size, linearly, of even its bulkier congeners of the lower formation of the coccosteus. after examining many a drawer, stored, from the deposits of the neighborhood, with characteristic fossils of the lias, the weald, and the oölite, and of the upper and lower old red, we set out together to expatiate amid the treasures of the town museum. among other recent additions to the museum, there is an interesting set of the fishes of the ganges, the donation of a gentleman long resident in india, to which mr. duff called my attention, as illustrative, in some of the specimens, of the more characteristic ichthyolites of the old red sandstone. one numerous family, the pimelodi, abundantly represented in the gangetic region, in not only the rivers, but also the ponds, tanks, and estuaries of the district, is certainly worthy the careful study of the geologist. it approaches nearer, in some of its more strongly-marked genera, to the coccosteus of the lower old red, than any other tribe of existing fishes which i have yet seen. the body of the pimelodus, from the anterior dorsal downwards, is as naked as that of the eel; whereas the head, and in several of the species the back, is armed with strong plates of naked bone, curiously fretted, as in many of the ichthyolites of the lower, and more especially of the upper old red sandstone, into ridges of confluent tubercles, that radiate from the centre to the edges of the plates. the dorsal plate, too, when detached, as in many of the species, from the plates of the head, bears upon its inner side a strong central ridge, that deepens as it descends, till it abruptly terminates a little short of the termination of the plate, exactly as in the dorsal plate of coccosteus, which sunk its central ridge deep into the back of the animal. the point of resemblance to be mainly noticed, however, is the contrast furnished by the powerful armature of the head and back, with the unprotected nakedness of the posterior portions of the creature;--a point specially noticeable in the coccosteus, and apparent also, though in a lesser degree, in some of the other genera of the old red, such as the pterichthyes and asterolepides. from the snout of the coccosteus down to the posterior termination of the dorsal plate, the creature was cased in strong armor, the plates of which remain as freshly preserved in the ancient rocks of the country as those of the pimelodi of the ganges on the shelves of the elgin museum; but from the pointed termination of the plate immediately over the dorsal fin, to the tail, comprising more than one half the entire length of the animal, all seems to have been exposed, without the protection of even a scale, and there survives in the better specimens only the internal skeleton of the fish and the ray-bones of the fins. it was armed, like a french dragoon, with a strong helmet and a short cuirass; and so we find its remains in the state in which those of some of the soldiers of napoleon's old guard, that had been committed unstripped to the earth, may be dug up in the future on the fatal field of borodino, or along the banks of the dwina or the wap. the cuirass lies still attached to the helmet, but we find only the naked skeleton attached to the cuirass. the pterichthys to its strong helmet and cuirass added a posterior armature of comparatively feeble scales, as if, while its upper parts were shielded with plate armor, a lighter covering of ring or scale armor sufficed for the less vital parts beneath. in the asterolepis the arrangement was somewhat similar, save that the plated cuirass was wanting: it was a strongly helmed warrior in slight scale armor; for the disproportion between the strength of the plated head-piece and that of the scaly coat was still greater than in the pterichthys. the occipital star-covered plates are, in some of the larger specimens, fully three-quarters of an inch in thickness, whereas the thickness of the delicately-fretted scales rarely exceeds a line. why this disproportion between the strength of the armature in different parts of the same fish should have obtained, as in pterichthys and asterolepis, or why, while one portion of the animal was strongly armed, another portion should have been left, as in coccosteus, wholly exposed, cannot of course be determined by the mere geologist. his rocks present him with but the fact of the disproportion, without accounting for it. but the natural history of existing fish, in which, as in the pimelodi, there may be detected a similar peculiarity of armature, may perhaps throw some light on the mystery. in hamilton's "fishes of the ganges" i find but little reference made to the instincts and habits of the animals described: their deep-river haunts lie, in many cases, beyond the reach of observation; and of the observations actually made, the descriptive naturalist, intent often on mere peculiarities of structure, is not unfrequently too careless. hamilton describes the habitats of the various indian species of pimelodi, whether brackish estuaries, ponds, or rivers, but not their characteristic instincts. of the silurus, however, a genus of the same great family, i read elsewhere that some of the species, such as the _silurus glanis_, being unwieldy in their motions, do not pursue their prey, which consists of small fishes, but lie concealed among the mud, and seize on the chance stragglers that come their way. and of the _pimelodus gulio_, a little, strongly-helmed fish, with a naked body, i was informed by mr. duff, on the authority of the gentleman who had presented the specimens to the museum, that it burrowed in the holes of muddy banks, from which it shot out its armed head, and arrested, as they passed, the minute animals on which it preyed. the animal world is full of such compensatory defences: there is a half-suit of armor given to shield half the body, and a wise instinct to protect the rest. the _pholas crispata_ cannot shut its valves so as to protect its anterior parts, without raising them from off those parts which lie behind: like the irishman in the haunted house, who attempted lengthening his blanket by cutting strips from the top and sewing them on to the bottom, it loses at the one end what it gains at the other; but, hemmed round by the solid walls of the recess which it is its nature to hollow out for itself in shale or stone, the anterior parts, though uncovered by the shell, are not exposed. by closing its valves anteriorly, it shuts the door of its little house, made like that of the coney-folk of scripture, in the rock; and then, of the entire cell in which it dwells so secure, what is not shut door is impregnable wall. the remark of paley, that the "human animal is the only one which is naked, and the only one which can clothe itself," is by no means quite correct. one half the hermit crab is as naked as the "human animal," and even less fitted for exposure; for it consists of a thin-skinned, soft, unmuscular bag, filled with delicate viscera; but not even the human animal is more skilful in clothing himself in the spoils of other animals than the hermit crab in wrapping up its naked bag in the strong shell of some dead fusus or buccinum, which it carries about with it in all its peregrinations, as at once clothes, armor, and house. nature arms its front, and it is itself wise enough to arm its rear. now, it seems not improbable that the half-armed coccosteus, a heavy fish, indifferently furnished with fins, may have burrowed, like the recent _silurus glanis_ or _pimelodus gulio_, in a thick mud,--of the existence of which in vast quantity, during the times of the old red sandstone, the dark caithness flagstones, the fetid breccia of strathpeffer, and the gray stratified clays of cromarty, moray, and banff, unequivocally testify; and that it may have thus not only succeeded in capturing many of its light-winged contemporaries, which it would have vainly pursued in open sea, but may have been enabled also to present to its enemies, when assailed in turn, only its armed portions, and to protect its unarmed parts in its burrow. it is further worthy of notice, that many of the pimelodi are furnished with spines, not, like those ichthyodorulites which occur so frequently in the older secondary and palæozoic divisions, unfinished in appearance at their lower extremity, as if, like the spines of the ancient acanthodi, or those of the recent dog-fish (_spinax acanthias_), they had been simply embedded in the flesh, but bearing, like the wings of the pterichthys, an articulated aspect. those of the _pimelodus rita_ and _pimelodus gagata_ are of singular beauty; and when the creatures have no further use for them, and the mud of the ganges has been consolidated into shale or baked into flagstone around them, they will make very exquisite fossils. a correct drawing of the plates and spines of some of the members of the pimelodi family, with a portion of the internal skeletons, arranged in their proper places, but divested of those more destructible parts to which they are attached, would serve admirably to show what strange forms fish not greatly removed from the ordinary type may assume in the fossil state, and might throw some light on the extraordinary appearance assumed, as ichthyolites, by the old family of the cephalaspians. the geological department of the elgin museum is not yet very complete. the private collections of the locality, by forestalling, greatly restrict the supply from the rich deposits in the neighborhood, and have an unquestioned right to do so. the museum contains, however, several interesting organisms. i saw, among the others, a specimen of diplopterus, that showed the form and position of the fins of this rather rare ichthyolite much better than any of the morayshire specimens portrayed by agassiz in his great work; and beside it, one of the two specimens of _pterichthys oblongus_ which he figures, and on which he establishes the species. the other individual,--a cromarty specimen,--graces my little collection. the gloomy day passed pleasantly in deciphering, with so accomplished a geologist as mr. duff, these curious hieroglyphics of the old world, that tell such wonderful stories, and in comparing _viva voce_, as we were wont to do long years before in lengthy epistles, our respective notions regarding the true key for laying open their more occult meanings. and, after sharing with him in his family dinner, i again took my seat on the mail, as a chill, raw evening was falling, and rode on, some six or eight and twenty miles, to campbelton. the rain pattered drearily through the night on my bed-room window; and as frequent exposure to the wet had begun to tell on a constitution not altogether so strong as it had once been, i awakened oftener than was quite comfortable, to hear it. the morning, however, was dry, though gray and sunless; and, taking an early breakfast at the inn, i traversed the flat gravelly points of ardersier and fortrose, that, projecting like moles far into the frith, narrow the intervening ferry to considerably less than one-third the width which it would present were they away. the origin of these long detrital promontories, which form, when viewed from the heights on either side, so peculiar a feature in the landscape, and which, were they directly opposite, instead of being set down a mile awry, would shut up the opening altogether, has not yet been satisfactorily accounted for. one special theory assigns their formation to the agency of the descending tide, striking in zig-gig style, in consequence of some peculiarity of the coast-line or of the bottom, from side to side of the frith, and depositing a long trail of sand and gravel, at nearly right angles with the beach, first on the one shore and then on the other. but why the tide, which runs in various zig-zag crossings in the course of the frith, should have the effect here, and nowhere else, of raising two vast mounds, each a full mile and a quarter in length, with an average breadth of from two to five furlongs, is by no means very apparent. certainly the present tides of the frith could not have formed them, nor could they have been elevated to their present average height of ten or twelve feet over the flood-line in a sea standing at the existing level. if they in reality originated in this cause, it must have been ere the latter upheavals of the land or recessions of the sea, when the great caledonian valley existed as a narrow ocean sound, swept by powerful currents. upon another and entirely different hypothesis, these flat promontories have been regarded as the remains, levelled by the waves, and gapped direct in the middle by the tide, of a vast transverse morain of the great valley, belonging to the same glacial age as the lateral morains some ten or fifteen miles higher up, that extend from the immediate neighborhood of inverness to the mansion-house of dochfour. but this hypothesis, like the other, is not without its difficulties. why, for instance, should the promontories be a mile awry? there is, however, yet another mode of accounting for their formation, which i am not in the least disposed to criticise. they were constructed, says tradition, through the agency of the arch-wizard michael scott. michael had called up the hosts of faery to erect the cathedral of elgin and the chanonry kirk of fortrose, which they completed from foundation to ridge, each in a single night,--committing, in their hurry, merely the slight mistake of locating the building intended for elgin in fortrose, and that intended for fortrose in elgin; but, their work over and done, and when the magician had no further use for them, they absolutely refused to be _laid_; and, like a _posse_ of irish laborers thrown out of a job, came thronging round him, clamoring for more employment. fearing lest he should be torn in pieces,--a catastrophe which has not unfrequently happened in such circumstances in the olden time, and of which those recent philanthropists who engage themselves in finding work for the unemployed may have perhaps entertained some little dread in our own days,--he got rid of them for the time by setting them off in a body to run a mound across the moray frith from fortrose to ardersier. toiling hard in the evening of a moonlight night, they had proceeded greatly more than two-thirds towards the completion of the undertaking, when a luckless highlander passing by bade god-speed the work, and, by thus breaking the charm, arrested at once and forever the construction of the mound, and saved the navigation of inverness. i stood for a few seconds at the burn of rosemarkie undecided whether i should take the scarfs-craig road,--a break-neck path which runs eastwards along the cliffs, and which, though the rougher, is the more direct cromarty line of the two,--or the considerably better though longer line of the white bog, which strikes upwards along the burn in a westerly direction, and joins the cromarty and inverness highway on the moor of the maolbuie. i had got into a part of the country where every little locality, and every more striking feature in the landscape, has its associated tradition; and the pause of a few moments at the two roads recalled to my memory the details of a ghost-story, long regarded in the district in which it was best known as one of the most authentic of its class, but which seems by no means inexplicable on natural principles.[ ] chapter v. rosemarkie and its scaurs--kaes' craig--a jackdaw settlement--"rosemarkie kaes" and "cromarty cooties"--"the danes," a group of excavations--at home in cromarty--the boulder-clay of cromarty "begins to tell its story"--one of its marked scenic peculiarities--hints to landscape painters--"samuel's well"--a chain of bogs geologically accounted for--another scenic peculiarity--"_ha-has_ of nature's digging"--the author's earliest field of hard labor--picturesque cliff of boulder-clay--scratchings on the sandstone--invariable characteristic of true boulder-clay--scratchings on pebbles in the line of the longer axis--illustration from the boulder-clay of banff. rosemarkie, with its long narrow valley and its red abrupt _scaurs_,[ ] is chiefly interesting to the geologist for its vast beds of the boulder-clay. i am acquainted with no other locality in the kingdom where this deposit is hollowed into ravines so profound, or presents precipices so imposing and lofty. the clay lies thickly over most part of the black isle and the peninsula of easter ross,--both soft sandstone districts,--bearing everywhere an obvious relation, as a deposit, to both the form and the conditions of exposure of the existing land,--just as the accumulated snow of a long-lying snow-storm, exposed to the drifting wind, bears relation to the heights and hollows of the tracts which it covers. on the higher eminences the clay forms a comparatively thin stratum, and in not a few instances it has been wholly worn away; while on the lower grounds, immediately over the old coast line, and in the sides of hollow valleys,--exactly such places as we might expect to see the snow occupying most deeply after a night of drift,--we find it accumulated in vast beds of from eighty to an hundred feet in thickness. one of these occurs in the opening of the narrow valley along which my course this morning lay, and is known far and wide,--for it forms a marked feature in the landscape, and harbors in its recesses a countless multitude of jackdaws,--as the "kaes' craig of rosemarkie." it presents the appearance of a hill that had been cut sheer through the middle from top to base, and exhibits in its abrupt front a broad red perpendicular section of at least a hundred feet in height, barred transversely by thin layers of sand, and scored vertically by the slow action of the rains. originally it must have stretched its vanished limb across the opening like some huge snow-wreath accumulated athwart a frozen rivulet; but the incessant sweep of the stream that runs through the valley has long since amputated and carried it away; and so only half the hill now remains. the kaes' craig resembles in form a lofty chalk cliff, square, massy, abrupt, with no sloping fillet of vegetation bound across its brow, but precipitous direct from the hill-top. the little ancient village of rosemarkie stretches away from its base on the opposite side of the stream; and on its summit and along its sides, groups of chattering jackdaws, each one of them as reflective and philosophic as the individual immortalized by cowper, look down high over the chimneys into the streets. the clay presents here, more than in almost any other locality with which i am acquainted, the character of a stratified deposit; and the numerous bands of sand by which the cliff is horizontally streaked from top to bottom we find hollowed, as we approach, into a multitude of circular openings, like shot-holes in an old tower, which form breeding-places for the daw and the sand-martin. the biped inhabitants of the cliff are greatly more numerous than the biped inhabitants of the quiet little hamlet below; and on fortrose fair-days, when, in virtue of an old feud, the rosemarkie boys were wont to engage in formidable bickers with the boys of cromarty, i remember, as one of the invading belligerents, that, in bandying names with them in the fray, we delighted to bestow upon them, as their hereditary sobriquet, given, of course, in allusion to their feathered neighbors, the designation of the "_rosemarkie kaes_." cromarty, however, is two-thirds surrounded by the waters of a frith abounding in sea-fowl; and the little fellows of rosemarkie, indignant at being classed with their _kaes_, used to designate us with hearty emphasis, in turn, as the "_cromarty cooties_," _i.e._, coots. a little higher up the valley, on the western side, there occurs in the clay what may be termed a _group_ of excavations, composing a piece of scenery ruinously broken and dreary, and that bears a specific character of its own which scarce any other deposit could have exhibited. the excavations are of considerable depth and extent,--hollows out of which the materials of pyramids might have been taken. the precipitous sides are fretted by jutting ridges and receding inflections, that present in abundance their diversified alternations of light and shadow. the steep descents form cycloid curves, that flatten at their bases, and over which the ferruginous stratum of mould atop projects like a cornice. between neighboring excavations there stand up dividing walls, tall and thin as those of our city buildings, and in some cases broken at their upper edges into rows of sharp pinnacles or inaccessible turf-coped turrets; while at the bottom of the hollows, washed by the runnels which, in the slow lapse of years, have been the architects of the whole, we find cairn-like accumulations of water-rolled stones,--the disengaged pebbles and boulders of the deposit. the boulders and pebbles project also from the steep sides, at all heights and of all sizes, like the primary masses inclosed in our ancient conglomerates, when exhibited in wave-worn precipices,--forcing upon the mind the conclusion that the boulder-clay is itself but an unconsolidated conglomerate of the later periods, which occupies nearly the same relative position to the existing vegetable mould, with all its recent productions, that the great conglomerate of the old red sandstone occupies in relation to the lower ichthyolite beds of that system, with their numerous extinct organisms. but its buried stones are fretted with hieroglyphic inscriptions, in the form of strange scratchings and polishings, grooves, ridges, and furrows,--always associated with the boulder-clays,--which those of the more ancient conglomerates want, and which, though difficult to read, seem at length to be yielding up the story which they record. of this, however, more anon. viewed by moonlight, when the pale red of the clay where the beam falls direct is relieved by the intense shadows, these excavations of the valley of rosemarkie form scenes of strange and ghostly wildness: the projecting, buttress-like angles,--the broken walls,--the curved inflections,--the pointed pinnacles,--the turrets, with their masses of projecting coping,--the utter lack of vegetation, save where the heath and the furze rustle far above,--all combine to form assemblages of dreary ruins, amid which, in the solitude of night, one almost expects to see spirits walk. these excavations have been designated, from time immemorial, by the neighboring town's-people, as "the danes;" but whether the name be, as is most probable, merely a corruption of an appropriate enough saxon word, "the dens," or derived, as a vague tradition is said to testify, from the ages of danish invasion, it is not quite the part of the geologist to determine. it may be worth mentioning, however, from its bearing on the point, that there are two excavations in the boulder-clay near cromarty, one of which has been long known by the name of "the morial's den," while the other, greatly smaller in size, rejoices in the double diminutive of "the little dennie." for an hour or so the danes proved agreeable though somewhat silent companions; and then, climbing the opposite side of the valley, i gained the high road, and, walking on to cromarty, found myself once more among "the old familiar faces." in a few days the storm blew by; and as the prolonged rains had cleared out the deep ravines of the district, and given to the boulder-clay in which they are scooped a freshness in its section analogous to fresh fracture in rocks of harder consistency, i availed myself of the facilities afforded me in consequence, for exploring it once more. it has long constituted one of the hardest of the many riddles with which our scottish deposits exercise the patience and ingenuity of the geologist. i remember a time when, after passing a day under its barren _scaurs_, or hid in its precipitous ravines, i used to feel in the evening as if i had been travelling under the cloud of night, and had seen nothing. it was a morose and taciturn companion, and had no speculation in it. i might stand in front of its curved precipices, red, yellow or gray, according to the prevailing average color of the rocks on which it rests, and mark their water-rolled boulders, of all qualities and sizes, sticking out in bold relief from the surface, like the rock-like protuberances that roughen the rustic basements of the architect, from the line of the wall; but i had no _open sesame_ to form vistas through them into the recesses of the past. i saw merely the stiff pastry matrix of which they are composed, and the inclosed pebbles. but the boulder-clay has of late become more sociable; and, though with much hesitancy and irresolution, like old mr. spectator on the first formal opening of his mouth,--a consequence, doubtless, in both cases of previous habits of silence long indulged,--it begins to tell its story. and a most curious story it is. the morning was clear, but just a little chill; and a soft covering of snow, that had fallen during the storm on the flat summit of ben-wevis, and showed its extreme tenuity by the paleness of its tint of watery blue, was still distinctly visible at the distance of full twenty miles. the sun, low in the sky,--for the hour was early,--cast its slant rays athwart the prospect, giving to each nearer bank and hillock, and to the more distant protuberances on the mountain-sides, those well-defined accompaniments of shadow that serve by throwing the minor features of a landscape upon the eye in bold relief, to impart to it an air of higher finish and more careful filling up than it ever bears under a more vertical light. i took the road which, leading westward from the town towards invergordon ferry, skirts the frith on the one hand, and runs immediately under the noble escarpment of green bank formed by the old coast line on the other. fully two-thirds of the entire height of the rampart here, which rises in all about a hundred feet over the sea-level, is formed of the boulder-clay; and i am acquainted with no locality in which the deposit presents more strongly, for at least the first half mile, one of its marked scenic peculiarities. it is furrowed vertically on the slope, as if by enormous flutings in the more antique doric style; and the ridges by which these are separated,--each from a hundred to a hundred and fifty feet in length, and from five-and-twenty to thirty feet in average height,--resemble those burial mounds with which the sexton frets the churchyard turf; with this difference, however, that they seem the burial mounds of giants, tall and bulky as those that of old warred against the gods. they are striking enough to have caught the eye of the children of the place, and are known among them as the giants' graves. i could fain have taken their portrait in a calotype this morning, as they lay against the green bank,--their feet to the shore, and their heads on the top of the escarpment,--like patients on a reclining bed, and strongly marked, each by its broad bar of yellow light and of dark shadow, like the ebon and ivory buttresses of the poet. this little vignette, i would have said to the landscape painter, represents the boulder-clay, after its precipitous banks--worn down, by the frosts and rains of centuries, into parallel runnels, that gradually widened into these hollow grooves--had sunk into the angle of inclination at which the disintegrating agents ceased to operate, and the green sward covered all up. you must be studying these peculiarities of aspect more than ever you studied them before. there is a time coming when the connoisseur will as rigidly demand the specific character of the various geologic rocks and deposits in your hills, _scaurs_, and precipices, as he now demands specific character in your shrubs and trees. it is worthy the notice of the young geologist, who has just set himself to study the various effects produced on the surface of a country by the deposits which lie under it, that for about a quarter of a mile or so, the base of the escarpment here is bordered by a line of bogs, that bear in the driest weather their mantling of green. they are fed with a perennial supply of water, by a range of deep-seated springs, that come bursting out from under the boulder-clay; and one of their number, which bears i know not why, the name of samuel's well, and yields its equable flow at an equable temperature, summer and winter, into a stone trough by the way-side, is not a little prized by the town's-people, and the seamen that cast anchor in the opposite roadstead, for the lightness and purity of its water. what is specially worthy of notice in the case is, the very definite beginning and ending of the chain of bogs. all is dry at the base of the escarpment, up to the point at which they commence; and then all is equally dry at the point at which they terminate. and of exactly the same extent,--beginning where the bogs begin, and ending where they end,--we may trace an ancient stratum of pure sand,--of considerable thickness, intercalated between the base of the clay and the superior surface of the old red sandstone. it is through this permeable sand that the profoundly seated springs find their way to the surface,--for the clay is impermeable; and where it comes in contact with the rock on either side of the arenaceous stratum, the bogs cease. the chain of green bogs is a consequence of the stratum of permeable sand. i have in vain sought this ancient layer of sand,--decidedly of the same era with the argillaceous bed which overlies it,--for aught organic. a single shell, so unequivocally of the period of the boulder-clay as to occur at the base of the deposit, would be worth, i have said, whole drawerfuls of fossils furnished by the better-known deposits. but i have since seen in abundance shells of the boulder-clay. there is another scenic peculiarity of the clay, which the neighborhood of cromarty finely illustrates, and of which my walk this morning furnished numerous striking instances. the giants' graves--to borrow from the children of the place--occur on the steep slopes of the old coast line, or in the sides of ravines, where the clay, as i have said, had once presented a precipitous front, but had been gradually moulded, under the attritive influences of the elements, into series of alternating ridges and furrows, which, when they had flattened into the proper angle, the green sward covered up from further waste. but the deep dells and narrow ravines in which many ranges of these graves occur are themselves peculiarities of the deposit. wherever the boulder-clay lies thick and continuous, as in the parish of cromarty, on a sloping table-land, every minute streamlet cuts its way to the solid rock at the bottom, and runs through a deep dell, either softened into beauty by the disintegrating process, or with all its precipices standing up raw and abrupt over the stream. four of these ravines, known as the "old chapel burn," the "ladies' walk," the "morial's den," and the "red burn," each of them cutting the escarpment of the ancient coast line from top to base, and winding far into the interior, occur in little more than a mile's space; and they lie still more thickly farther to the west. these dells of the boulder clay, in their lower windings,--for they become shallower and tamer as they ascend, till they terminate in the uplands in mere _drains_, such as a ditcher might excavate at the rate of a shilling or two per yard,--are eminently picturesque. on those gentler slopes where the vegetable mould has had time and space to accumulate, we find not a few of the finest and tallest trees of the district. there is a bosky luxuriance in their more sheltered hollows, well known to the schoolboy what time the fern begins to pale its fronds, for their store of hips, sloes, and brambles; and red over the foliage we may see, ever and anon as we wend upwards, the abrupt frontage of some precipitous _scaur_, suited to remind the geologist, from its square form and flat breadth of surface, of the cliffs of the chalk. when viewed from the sea, at the distance of a few miles, these ravines seem to divide the sloping tracts in which they occur into large irregular fields, laid out considerably more in accordance with the principles of the landscape gardener than the stiffly squared rectilinear fields of the agriculturist. they are _ha-has_ of nature's digging; and their bottom and sides in this part of the country we still find occupied in a few cases--though in many more they have been ravaged by the wasteful axe--by noble forest-_hedges_, tall enough to overtop, in at least their middle reaches, the tracts of table-land which they divide. i passed, a little farther on, the quarry of old red sandstone, with a huge bank of boulder-clay resting over it, in which i first experienced the evils of hard labor, and first set myself to lessen their weight by becoming an observer of geological phenomena. it had been deserted apparently for many years; and the debris of the clay partially covered up, in a sloping talus, the frontage of rock beneath. old red sandstone and boulder-clay, a broad bar of each!--such was the compound problem which the excavation propounded to me when i first plied the tool in it,--a problem equally dark at the time in both its parts. i have since got on a very little way with the old red portion of the task; but alas for the boulder-clay portion of it! a bar of impenetrable shadow has rested long and obstinately over the newer deposit; and i scarce know whether the light which is at length beginning to play on its pebbly front be that of the sun or of a delusive meteor. but courage, patient hearts! the boulder-clay will one day yield up _its_ secret too. still further on by a few hundred yards, i could have again found use for the calotype, in transferring to paper the likeness of a protuberant picturesque cliff, which, like the giants' graves, could have belonged, of all our scotch deposits, to only the boulder-clay. it stands out, on the steep acclivity of a furze-covered bank, abrupt as a precipice of solid rock, and yet seamed by the rain into numerous divergent channels, with pyramidal peaks between; and, combining the perpendicularity of a true cliff with the water-scooped furrows of a yielding clay, it presents a peculiarity of aspect which strikes, by its grotesqueness, eyes little accustomed to detect the picturesque in landscape. i remember standing to gaze upon it when a mere child; and the fisher children of the neighboring town still tell that "_it has been prophesied_" it will one day fall, "and kill a man and a horse on the road below,"--a legend which shows it must have attracted _their_ notice too. i selected as the special scene of exploration this morning, a deep ravine of the boulder-clay, which had been recently deepened still more by the waters of a mill-pond, that had burst during a thunder-shower, and, after scooping out for themselves a bed in the clay some twelve or fifteen feet deep, where there had been formerly merely a shallow drain, had then tumbled into the ravine, and bared it to the rock. the sandstones of the district, soft and not very durable, show the scratched and polished surfaces but indifferently well, and, when exposed to the weather, soon lose them; but in the bottom of the runnel by which the ravine is swept i found them exceedingly well marked,--the polish as decided as the soft red stone could receive, and the lines of scratching running in their general bearing due east and west, at nearly right angles with the course of the stream. wherever the rock had been laid bare during the last few months, _there_ were the markings; wherever it had been laid bare for a few twelvemonths, they were gone. i next marked a circumstance which has now for several years been attracting my attention, and which i have found an invariable characteristic of the true boulder-clay. not only do the rocks on which the deposit rests bear the scratched and polished surfaces, but in every instance the fragments of stone which it incloses bear the scratchings also, if from their character capable of receiving and retaining such markings, and neither of too coarse a grain nor of too hard a quality. if of limestone, or of a coherent shale, or of a close, finely-grained sandstone, or of a yielding trap, they are scratched and polished,--invariably on one, most commonly on both their sides; and it is a noticeable circumstance, that the lines of the scratchings occur, in at least nine cases out of every ten, in the lines of their longer axes. when decidedly oblong or spindle-shaped, the scratchings run lengthwise, preserving in most cases, on the under and upper sides, when both surfaces are scratched, a parallelism singularly exact; whereas, when of a broader form, so that the length and breadth nearly approximate,--though the lines generally find out the longer axis, and run in that direction,--they are less exact in their parallelism, and are occasionally traversed by cross furrows. of such certain occurrence is this longitudinal lining on the softer and finer-grained pebbles of the boulder-clay, that i have come to regard it as that special characteristic of the deposit on which i can most surely rely for purposes of identification. i am never quite certain of the boulder-clay when i do not detect it, nor doubtful of the true character of the deposit when i do. when examining, for instance, the accumulation of broken liasic materials in the neighborhood of banff, i made it my first care to ascertain whether the bank inclosed fragments of stone or shale bearing the longitudinal markings; and felt satisfied, on finding that it did, that i had discovered the period of its re-formation. chapter vi. organisms of the boulder-clay not unequivocal--first impressions of the boulder-clay--difficulty of accounting for its barrenness of remains--sir charles lyell's reasoning--a fact to the contrary--human skull dug from a clay-bank--the author's change of belief respecting organic remains of the boulder-clay--shells from the clay at wick--questions respecting them settled--conclusions confirmed by mr. dick's discoveries at thurso--sir john sinclair's discovery of boulder-clay shells in --comminution of the shells illustrated--_cyprina islandica_--its preservation in larger proportions than those of other shells accounted for--boulder-clays of scotland reformed during the existing geological epoch--scotland in the period of the boulder-clay "merely three detached groups of islands"--evidence of the subsidence of the land in scotland--confirmed by rev. mr. cumming's conclusion--high-lying granite boulders--marks of a succeeding elevatory period--scandinavia now rising--autobiography of a boulder desirable--a story of the supernatural. for the greater part of a quarter of a century i had been finding organisms in abundance in the boulder-clay, but never anything organic that unequivocally belonged to its own period. i had ascertained that it contains in ross and cromarty nodules of the old red sandstone, which bear inside, like so many stone coffins, their well laid out skeletons of the dead; but then the markings on their surface told me that when the boulder-clay was in the course of deposition, they had been exactly the same kind of nodules that they are now. in moray, it incloses, i had found, organisms of the lias; but _they_ also testify that they present an appearance in no degree more ancient at the present time than they did when first enveloped by the clay. in east and west lothian too, and in the neighborhood of edinburgh, i had detected in it occasional organisms of the mountain limestone and the coal measures; but these, not less surely than its liasic fossils in moray, and its old red ichthyolites in cromarty and ross, belonged to an incalculably more ancient state of things than itself; and--like those shrivelled manuscripts of pompeii or herculaneum, which, whatever else they may record, cannot be expected to tell aught of the catastrophe that buried them up--they throw no light whatever on the deposit in which they occur. i at length came to regard the boulder-clay--for it is difficult to keep the mind in a purely blank state on any subject on which one thinks a good deal--as representative of a chaotic period of death and darkness, introductory, mayhap, to the existing scene of things. after, however, i had begun to mark the invariable connection of the clay, as a deposit, with the dressed surfaces on which it rests, and the longitudinal linings of the pebbles and boulders which it incloses, and to associate it, in consequence, with an ice-charged sea and the great gulf stream, it seemed to me extremely difficult to assign a reason why it should be thus barren of remains. sir charles lyell states, in his "elements," that the "stranding of ice-islands in the bays of iceland since has driven away the fish for several successive seasons, and thereby caused a famine among the inhabitants of the country;" and he argues from the fact, "that a sea habitually infested with melting ice, which would chill and freshen the water, might render the same uninhabitable by marine mollusca." but then, on the other hand, it is equally a fact that half a million of seals have been killed in a single season on the meadow-ice a little to the north of newfoundland, and that many millions of cod, besides other fish, are captured yearly on the shores of that island, though grooved and furrowed by ice-floes almost every spring. of the seal family it is specially recorded by naturalists, that many of the species "are from choice inhabitants of the margins of the frozen seas towards both poles; and, of course, in localities in which many such animals live, some must occasionally die." and though the grinding process would certainly have disjointed, and might probably have worn down and partially mutilated, the bones of the amphibious carnivora of the boulder period, it seems not in the least probable, judging from the fragments of loose-grained sandstone and soft shale which it has spared, that it would have wholly destroyed them. so it happened, however, that from north berwick to the ord hill of caithness, i had never found in the boulder-clay the slightest trace of an organism that could be held to belong to itself; and as it seems natural to build on negative evidence, if very extensive, considerably more than mere negative evidence, whatever the circumstances, will carry, i became somewhat skeptical regarding the very existence of boulder-fossils,--a skepticism which the worse than doubtful character of several supposed discoveries in the deposit served considerably to strengthen. the clay forms, when cut by a water-course, or assailed on the coast by some unusually high tide, a perpendicular precipice, which in the course of years slopes into a talus; and as it exhibits in most instances no marks of stratification, the clay of the talus--a mere re-formation of fragments detached by the frosts and rains from the exposed frontage--can rarely be distinguished from that of the original deposit. now, in these consolidated slopes it is not unusual to find remains, animal and vegetable, of no very remote antiquity. i have seen a human skull dug out of the reclining base of a clay-bank once a precipice, fully six feet from under the surface. it might have been deemed the skull of some long-lived contemporary of enoch,--one of the accursed race, mayhap, "who sinned and died before the avenging flood." but, alas! the laborer dug a little further, and struck his pickaxe against an old rybat that lay deeper still. there could be no mistaking the character of the champfered edge, that still bore the marks of the tool, nor that of the square perforation for the lock-bolt; and a rising theory, that would have referred the boulder-clay to a period in which the polar ice, set loose by the waters of the noachian deluge, came floating southwards over the foundered land, straightway stumbled against it, and fell. both rybat and skull had come from an ancient burying-ground, that occupies a projecting angle of the table-land above. i must now state, however, that my skepticism has thoroughly given way; and that, slowly yielding to the force of positive evidence, i have become as assured a believer in the _comminuted recent shells_ of the boulder-clay as in the belemnites of the oölite and lias, or the ganoid ichthyolites of the old red sandstone. i had marked, when at wick, on several occasions, a thick boulder-clay deposit occupying the southern side of the harbor, and forming an elevated platform, on which the higher parts of pulteneytown are built; but i had noted little else regarding it than that it bears the average dark-gray color of the flagstones of the district, and that some of the granitic boulders which protrude from its top and sides are of vast size. on my last visit, however, rather more than two years ago, when sauntering along its base, after a very wet morning, awaiting the orkney steamer, i was surprised to find, where a small slip had taken place during the rain, that it was mottled over with minute fragments of shells. these i examined, and found, so far as, in their extremely broken condition, i dared determine the point, that they belonged in such large proportion to one species,--the _cyprina islandica_ of dr. fleming,--that i could detect among them only a single fragment of any other shell,--the pillar, apparently, of a large specimen of _purpura lapillus_. both shells belong to that class of old existences,--long descended, without the pride of ancient descent,--which link on the extinct to the recent scenes of being. _cyprina islandica_ and _purpura lapillus_ not only exist as living molluscs in the british seas, but they occur also as crag-shells, side by side with the dead races that have no place in the present fauna. at this time, however, i could but think of them simply in their character as recent molluscs; and as it seemed quite startling enough to find them in a deposit which i had once deemed representative of a period of death, and still continued to regard as obstinately unfossiliferous, i next set myself to determine whether it really _was_ the boulder-clay in which they occurred. almost the first pebble which i disengaged from the mass, however, settled the point, by furnishing the evidence on which for several years past i have been accustomed to settle it;--it bore in the line of its longer axis, on a polished surface, the freshly-marked grooves and scratchings of the iceberg era. still, however, i had my doubts, not regarding the deposit, but the shells. might they not belong merely to the talus of this bank of boulder-clay?--a re-formation, in all probability, not _more_ ancient than the elevation of the most recent of the old coast lines,--perhaps greatly less so. meeting with an intelligent citizen of wick, mr. john cleghorn, i requested him to keep a vigilant eye on the shells, and to ascertain for me, when opportunity offered, whether they occurred deep in the deposit, or were restricted to merely the base of its exposed front. on my return from orkney, he kindly brought me a small collection of fragments, exclusively, so far as i could judge, of _cyprina islandica_, picked up in fresh sections of the clay; at the same time expressing his belief that they really belonged to the deposit as such, and were not accidental introductions into it from the adjacent shore. and at this point for nearly two years the matter rested, when my attention was again called to it by finding, in the publication of mr. keith johnston's admirable geological map of the british islands, edited by professor edward forbes, that other eyes than mine had detected shells in the boulder-clay of caithness. "cliffs of pleistocene," says the professor, in one of his notes attached to the map, "occur at wick, containing boreal shells, especially _astarte borealis_." i had seen the boulder-clay characteristically developed in the neighborhood of thurso; but, during a rather hurried visit, had lacked time to examine it. the omission mattered the less, however, as my friend mr. robert dick is resident in the locality; and there are few men who examine more carefully or more perseveringly than he, or who can enjoy with higher relish the sweets of scientific research. i wrote him regarding professor forbes's decision on the boulder-clay of wick and its shells; urging him to ascertain whether the boulder-clay of thurso had not its shells also. and almost by return of post i received from him, in reply, a little packet of comminuted shells, dug out of a deposit of the boulder-clay, laid open by the river thorsa, a full mile from the sea, and from eighty to a hundred feet over its level. he had detected minute fragments of shell in the clay about a twelvemonth before; but a skepticism somewhat similar to my own, added to the dread of being deceived by mere surface shells, recently derived from the shore in the character _of_ shell-sand, or of the edible species carried inland for food, and then transferred from the ash-pit to the fields, had not only prevented him from following up the discovery, but even from thinking of it as such. but he eagerly followed it up now, by visiting every bank of the boulder-clay in his locality within twenty miles of thurso, and found them all charged, from top to bottom, with comminuted shells, however great their distance from the sea, or their elevation over it. the fragments lie thick along the course of the thorsa, where the encroaching stream is scooping out the clay for the first time since its deposition, and laying bare the scratched and furrowed pebbles. they occur, too, in the depths of solitary ravines far amid the moors, and underlie heath, and moss, and vegetable mould, on the exposed hill-sides. the farm-house of dalemore, twelve miles from thurso as the crow flies, and rather more than thirteen miles from wick, occupies, as nearly as may be, the centre of the county; and yet there, as on the sea-shore, the boulder-clay is charged with its fragments of marine shells. though so barren elsewhere on the east coast of scotland, the clay is everywhere in caithness a shell-bearing deposit; and no sooner had mr. dick determined the fact for himself, at the expense of many a fatiguing journey, and many an hour's hard digging, than he found that it had been ascertained long before, though, from the very inadequate style in which it had been recorded, science had in scarce any degree benefited by the discovery. in the late sir john sinclair, distinguished for his enlightened zeal in developing the agricultural resources of the country, and for originating its statistics, employed a mineralogical surveyor to explore the underground treasures of the district; and the surveyor's journal he had printed under the title of "minutes and observations drawn up in the course of a mineralogical survey of the county of caithness, ann. , by john busby, edinburgh." now, in this journal there are frequent references made to the occurrence of marine shells in the blue clay. mr. dick has copied for me the two following entries,--for the work itself i have never seen:--" , sept. th.--surveyed down the river [thorsa] to geize; found blue clay-marl, _intermixed with marine shells_ in great abundance." "sept. th.--set off this morning for dalemore. bored for shell-marl in the 'grass-park;' found it in one of the quagmires, but to no great extent. bored for shell-marl in the 'house-park.' surveyed by the side of the river, and found blue clay-marl in great plenty, _intermixed with marine shells, such as those found at geize_. this place is supposed to be about twenty miles from the sea; and is one instance, among many in caithness, of _the ocean's covering the inland country at some former period of time_." the state of keeping in which the boulder-shells of caithness occur is exactly what, on the iceberg theory, might be premised. the ponderous ice-rafts that went grating over the deep-sea bottom, grinding down its rocks into clay, and deeply furrowing its pebbles, must have borne heavily on its comparatively fragile shells. if rocks and pebbles did not escape, the shells must have fared but hardly. and very hardly they have fared: the rather unpleasant casualty of being crushed to death must have been a greatly more common one in those days than in even the present age of railways and machinery. the reader, by passing half a bushel of the common shells of our shores through a barley-mill, as a preliminary operation in the process, and by next subjecting the broken fragments thus obtained to the attritive influence of the waves on some storm-beaten beach for a twelvemonth or two, as a finishing operation, may produce, when he pleases, exactly such a water-worn shelly debris as mottles the blue boulder-clays of caithness. the proportion borne by the fragments of one species of shell to that of all the others is very extraordinary. the _cyprina islandica_ is still by no means a rare mollusc on our scottish shores, and may, on an exposed coast, after a storm, be picked up by dozens, attached to the roots of the deep-sea tangle. it is greatly less abundant, however, than such shells as _purpura lapillus_, _mytilus edule_, _cardium edule_, _littorina littorea_, and several others; whereas in the boulder-clay it is, in the proportion of at least ten to one, more abundant than all the others put together. the great strength of the shell, however, may have in part led to this result; as i find that its stronger and massier portions,--those of the umbo and hinge-joint,--are exceedingly numerous in proportion to its slimmer and weaker fragments. "the _cyprina islandica_," says dr. fleming, in his "british animals," "is the largest british bivalve shell, measuring sometimes thirteen inches in circumference, and, exclusively of the animal, weighing upwards of nine ounces." now, in a collection of fragments of cyprina sent me by mr. dick, disinterred from the boulder-clay in various localities in the neighborhood of thurso, and weighing in all about four ounces, i have detected the broken remains of no fewer than _sixteen_ hinge joints. and on the same principle through which the stronger fragments of cyprina were preserved in so much larger proportion than the weaker ones, may cyprina itself have been preserved in much larger proportion than its more fragile neighbors. occasionally, however,--escaped, as if by accident,--characteristic fragments are found of shells by no means very strong,--such as _mytilus_, _tellina_, and _astarte_. among the univalves i can distinguish _dentalium entale_, _purpura lapillus_, _turritella terebra_, and _littorina littorea_, all existing shells, but all common also to at least the later deposits of the crag. and among the bivalves mr. dick enumerates,--besides the prevailing _cyprina islandica_,--_venus casina_, _cardium edule_, _cardium echinatum_, _mytilus edule_, _astarte danmoniensis_ (_sulcata_), and _astarte compressa_, with a _mactra_, _artemis_, and _tellina_.[ ] all the determined species here, with the exception of _mytilus edule_, have, with many others, been found by the rev. mr. cumming in the boulder-clays of the isle of man; and all of them are living shells at the present day on our scottish coasts. it seems scarce possible to fix the age of a deposit so broken in its organisms, on the principle that would first seek to determine its per centage of extinct shells as the data on which to found. one has to search sedulously and long ere a fragment turns up sufficiently entire for the purpose of specific identification, even when it belongs to a well-known living shell; and did the clay contain some six or eight per cent. of the extinct in a similarly broken condition (and there is no evidence that it contains a single per cent. of extinct shells), i know not how, in the circumstances, the fact could ever be determined. a lifetime might be devoted to the task of fixing their real proportion, and yet be devoted to it in vain. all that at present can be said is, that, judging from what appears, the boulder-clays of caithness, and with them the boulder-clays of scotland generally, and of the isle of man,--for they are all palpably connected with the same iceberg phenomena, and occur along the same zone in reference to the sea-level,--were formed during the _existing_ geological epoch. these details may appear tediously minute; but let the reader mark how very much they involve. the occurrence of recent shells largely diffused throughout the boulder-clays of caithness, at all heights and distances from the sea at which the clay itself occurs, and not only connected with the iceberg phenomena by the closest juxtaposition, but also testifying distinctly to its agency by the extremely comminuted state in which we find them, tell us, not only according to old john busby, "that the ocean covered the inland country at some former period of time," but that it covered it to a great height at a time geologically recent, when our seas were inhabited by exactly the same mollusca as inhabit them now, and so far as yet appears, by none others. i have not yet detected the boulder-clay at more than from six to eight hundred feet over the level of the sea; but the travelled boulders i have often found at more than a thousand feet over it; and dr. john fleming, the correctness of whose observations few men acquainted with the character of his researches or of his mind will be disposed to challenge, has informed me that he has detected the dressed and polished surfaces at least four hundred feet higher. there occurs a greenstone boulder, of from twelve to fourteen tons weight, says mr. m'laren, in his "geology of fife and the lothians," on the south side of black hill (one of the pentland range), at about fourteen hundred feet over the sea. now fourteen or fifteen hundred feet, taken as the extreme height of the dressings, though they are said to occur greatly higher, would serve to submerge in the iceberg ocean almost the whole agricultural region of scotland. the common hazel (_corylus avellana_) ceases to grow in the latitude of the grampians, at from one thousand two hundred to one thousand five hundred feet over the sea level; the common bracken (_pteris aquilina_) at about the same height; and corn is never successfully cultivated at a greater altitude. where the hazel and bracken cease to grow, it is in vain to attempt growing corn.[ ] in the period of the boulder-clay, then, when the existing shells of our coasts lived in those inland sounds and friths of the country that now exist as broad plains or fertile valleys, the sub-aërial superficies of scotland was restricted to what are now its barren and mossy regions, and formed, instead of one continuous land, merely three detached groups of islands,--the small cheviot and hartfell group,--the greatly larger grampian and ben nevis group,--and a group intermediate in size, extending from mealfourvonny, on the northern shores of loch ness, to the maiden paps of caithness. the more ancient boulder-clays of scotland seem to have been formed when the land was undergoing a slow process of subsidence, or, as i should perhaps rather say, when a very considerable area of the earth's surface, including the sea-bottom, as well as the eminences that rose over it, was the subject of a gradual depression; for little or no alteration appears to have taken place at the time in the _relative_ levels of the higher and lower portions of the sinking area: the features of the land in the northern part of the kingdom, from the southern flanks of the grampians to the pentland frith, seemed to have been fixed in nearly the existing forms many ages before, at the close, apparently, of the oölitic period, and at a still earlier age in the lammermuir district, to the south. and so the sea around our shores must have deepened in the ratio in which the hills sank. the evidence of this process of subsidence is of a character tolerably satisfactory. the dressed surfaces occur in scotland, most certainly, as i have already stated on the authority of dr. fleming, at the height of fourteen hundred feet over the present sea-level; it has been even said, at fully twice that height, on the lofty flanks of schehallion,--a statement, however, which i have had hitherto no opportunity of verifying. they may be found, too, equally well marked, under the existing high-water line; and it is obviously impossible that the dressing process could have been going on at the higher and lower levels at the same time. when the icebergs were grating along the more elevated rocks, the low-lying ones must have been buried under from three to seven hundred fathoms of water,--a depth from three to seven times greater, be it remembered, than that at which the most ponderous iceberg could possibly have grounded, or have in any degree affected the bottom. the dressing process, then, must have been a bit-and-bit process, carried on during either a period of elevation, in which the rising land was subjected, zone after zone, to the sweep of the armed ice from its higher levels _downwards_, or during a period of subsidence, in which it was subjected to the ice, zone after zone, from its lower levels _upwards_. and that it was the lower, not the higher levels, that were first dressed, appears evident from the circumstance, that though on these lower levels we find the rocks covered up by continuous beds of the boulder-clay, varying generally from twenty to a hundred feet in thickness, they are, notwithstanding, as completely dressed under the clay as on the heights above. had it been a rising land that was subjected to the attrition of the icebergs, the debris and dressings of the higher rocks would have protected the lower from the attrition; and so the thick accumulation of boulder-clay which overlies the old coast line, for instance, would have rested, not on dressed, but on undressed surfaces. the barer rocks of the lower levels might of course exhibit their scratchings and polishings, like those of the higher; but wherever these scratchings and polishings occurred in the inferior zones, no thick protecting stratum of boulder-clay would be found overlying them; and, _vice versa_, wherever in these zones there occurred thick beds of boulder-clay, there would be detected on the rock beneath no scratchings and polishings. in order to _dress_ the entire surface of a country from the sea-line and under it to the tops of its hills, and at the same time to cover up extensive portions of its low-lying rocks with vast deposits of clay, it seems a necessary condition of the process that it should be carried on piece-meal from the lower level upwards,--not from the higher downwards. it interested me much to find, that while from one set of appearances i had been inferring the gradual subsidence of the land during the period of the boulder-clay, the rev. mr. cumming of king william's college had arrived, from the consideration of quite a different class of phenomena, at a similar conclusion. "it appears to me highly probable," i find him remarking, in his lately published "isle of man," "that at the commencement of the boulder period there was a gradual sinking of this area [that of the island]. successively, therefore, the points at different degrees of elevation were brought within the influence of the sea, and exposed to the rake of the tides, charged with masses of ice which had been floated off from the surrounding shores, and bearing on their under surfaces, mud, gravel, and fragments of hard rock." mr. cumming goes on to describe, in his volume, some curious appearances, which seem to bear direct on this point, in connection with a boss of a peculiarly-compounded granite, which occurs in the southern part of the island, about seven hundred feet over the level of the sea. there rise on the western side of the boss two hills, one of which attains to the elevation of nearly seven hundred, and the other of nearly eight hundred feet over it; and yet both hills to their summits are mottled over with granite boulders, furnished by the comparatively low-lying boss. one of these travelled masses, fully two tons in weight, lies not sixty feet from the summit of the loftier hill, at an altitude of nearly fifteen hundred feet over the sea. now, it seems extremely difficult to conceive of any other agency than that of a rising sea or of a subsiding land, through which these masses could have been rolled up the steep slopes of the hills. had the boulder period been a period of elevation, or merely a stationary period, during which the land neither rose nor sank, the travelled boulders would not now be found resting at higher levels than that of the parent rock whence they were derived. we occasionally meet on our shores, after violent storms from the sea, stones that have been rolled from their place at low ebb to nearly the line of flood; but we always find that it was by the waves of the rising, not of the falling tide, that their transport was effected. for whatever removals of the kind take place during an ebbing sea are invariably in an opposite direction;--they are removals, not from lower to higher levels, but from higher to lower. the upper subsoils of scotland bear frequent mark of the elevatory period which succeeded this period of depression. the boulder-clay has its numerous intercalated arenaceous and gravelly beds, which belong evidently to its own era; but the numerous surface-beds of stratified sand and gravel by which in so many localities it is overlaid belong evidently to a later time. when, after possibly a long protracted period, the land again began to rise, or the sea to fall, the superior portions of the boulder-clay must have been exposed to the action of the tides and waves; and the same process of separation of parts must have taken place on a large scale, which one occasionally sees taking place in the present time on a comparatively small one, in ravines of the same clay swept by a streamlet. after every shower, the stream comes down red and turbid with the finer and more argillaceous portions of the deposit; minute accumulations of sand are swept to the gorge of the ravine, or cast down in ripple-marked patches in its deeper pools; beds of pebbles and gravel are heaped up in every inflection of its banks; and boulders are laid bare along its sides. now, a separation, by a sort of washing process of an analogous character, must have taken place in the materials of the more exposed portions of the boulder-clay, during the gradual emergence of the land; and hence, apparently, those extensive beds of sand and gravel which in so many parts of the kingdom exist, in relation to the clay, as a superior or upper subsoil; hence, too, occasional beds of a purer clay than that beneath, divested of a considerable portion of its arenaceous components, and of almost all its pebbles and boulders. this _washed_ clay,--a re-formation of the boulder deposit, cast down, mostly in insulated beds in quiet localities, where the absence of currents suffered the purer particles held in suspension by the water to settle,--forms, in scotland at least, with, of course, the exception of the ancient fire-clays of the coal measures, the true brick and tile clays of the agriculturist and architect. it is to these superior beds that all the recent shells yet found above the existing sea-level in scotland, from the dornoch frith and beyond it, to beyond the frith of forth, seem to belong. their period is much less remote than that of the shells of the boulder-clay, and they rarely occur in the same comminuted condition. they existed, it would appear, not during the chill twilight period, when the land was in a state of subsidence, but during the after period of cheerful dawn, when hill-top after hill-top was emerging from the deep, and the close of each passing century witnessed a broader area of dry land in what is now scotland, than the close of the century which had gone before. scandinavia is similarly rising at the present day, and presents with every succeeding age a more extended breadth of surface. many of the boulder-stones seem to have been cast down where they now lie, during this latter time. when they occur, as in many instances, high on bare hill-tops, from five to fifteen hundred feet over the sea-level, with neither gravel nor boulder-clay beside them, we of course cannot fix their period. they may have been dropped by ice-floes or shore-ice, where we now find them, at the commencement of the period of elevation, after the clay had been formed; or they may have been deposited by more ponderous icebergs during its formation, when the land was yet sinking, though during the subsequent rise the clay may have been washed from around them to lower levels. the boulders, however, which we find scattered over the plains and less elevated hill-sides, with beds of the washed gravel or sand interposed between them and the clay, must have been cast down where they lie, during the elevatory ages. for, had they been washed out of the clay, they would have lain, not _over_ the greatly lighter sands and gravels, but _under_ them. would that they could write their own histories! the autobiography of a single boulder, with notes on the various floras which had sprung up around it, and the various classes of birds, beasts, and insects by which it had been visited, would be worth nine-tenths of all the autobiographies ever published, and a moiety of the remainder to boot. a few hundred yards from the opening of this dell of the boulder-clay, in which i have so long detained the reader, there is a wooded inflection of the bank, formed by the old coast line, in which there stood, about two centuries ago, a meal-mill, with the cottage of the miller, and which was once known as the scene of one of those supernaturalities that belong to the times of the witch and the fairy. the upper anchoring-place of the bay lies nearly opposite the inflection. a shipmaster, who had moored his vessel in this part of the roadstead, some time in the latter days of the first charles, was one fine evening sitting alone on deck, awaiting the return of his seamen, who had gone ashore, and amusing himself in watching the lights that twinkled from the scattered farm-houses, and in listening, in the extreme stillness of the calm, to the distant lowing of cattle, or the abrupt bark of the herdsman's dog. as the hour wore later, the sounds ceased, and the lights disappeared,--all but one solitary taper, that twinkled from the window of the miller's cottage. at length, however, it also disappeared, and all was dark around the shores of the bay, as a belt of black velvet. suddenly a hissing noise was heard overhead; the shipmaster looked up, and saw what seemed to be one of those meteors known as falling stars, slanting athwart the heavens in the direction of the cottage, and increasing in size and brilliancy as it neared the earth, until the wooded ridge and the shore could be seen as distinctly from the ship-deck as by day. a dog howled piteously from one of the out-houses,--an owl whooped from the wood. the meteor descended until it almost touched the roof, when a cock crew from within; its progress seemed instantly arrested; it stood still, rose about the height of a ship's mast, and then began again to descend. the cock crew a second time; it rose as before; and, after mounting considerably higher than at first, again sank in the line of the cottage, to be again arrested by the crowing of the cock. it mounted yet a third time, rising higher still; and, in its last descent, had almost touched the roof, when the faint clap of wings was heard as if whispered over the water, followed by a still louder note of defiance from the cock. the meteor rose with a bound, and, continuing to ascend until it seemed lost among the stars, did not again appear. next night, however, at the same hour, the same scene was repeated in all its circumstances: the meteor descended, the dog howled, the owl whooped, the cock crew. on the following morning the shipmaster visited the miller's, and, curious to ascertain how the cottage would fare when the cock was away, he purchased the bird; and, sailing from the bay before nightfall, did not return until about a month after. on his voyage inwards, he had no sooner doubled an intervening headland, than he stepped forward to the bows to take a peep at the cottage: it had vanished. as he approached the anchoring ground, he could discern a heap of blackened stones occupying the place where it had stood; and he was informed on going ashore, that it had been burnt to the ground, no one knew how, on the very night he had quitted the bay. he had it re-built and furnished, says the story, deeming himself what one of the old schoolmen perhaps term the _occasional_ cause of the disaster. he also returned the cock,--probably a not less important benefit,--and no after accident befel the cottage. about fifteen years ago there was a human skeleton dug up near the scene of the tradition, with the skull, and the bones of the legs and feet, lying close together, as if the body had been huddled up twofold in a hole; and this discovery led to that of the story, which, though at one time often repeated and extensively believed, had been suffered to sleep in the memories of a few elderly people for nearly sixty years. chapter vii. relation of the deep red stone of cromarty to the ichthyolite beds of the system--ruins of a fossil-charged bed--journey to avoch--red dye of the boulder-clay distinct from the substance itself--variation of coloring in the boulder-clay red sandstone accounted for--hard-pan how formed--a reformed garden--an ancient battle-field--antiquity of geologic and human history compared--burn of killein--observation made in boyhood confirmed--fossil-nodules--fine specimen of _coccosteus decipiens_--blank strata of old red--new view respecting the rocks of black isle--a trip up moray and dingwall friths--altered color of the boulder-clay--up the auldgrande river--scenery of the great conglomerate--graphic description--laidlaw's boulder--_vaccinium myrtillus_--profusion of travelled boulders--the boulder _clach malloch_--its zones of animal and vegetable life. the ravine excavated by the mill-dam showed me what i had never so well seen before,--the exact relation borne by the deep red stone of the cromarty quarries to the ichthyolite beds of the system. it occupies the same place, and belongs to the same period, as those superior beds of the lower old red sandstone which are so largely developed in the cliffs of dunnet head in caithness, and of tarbet ness in ross-shire, and which were at one time regarded as forming, north of the grampians, the analogue of the new red sandstone. i paced it across the strata this morning, in the line of the ravine, and found its thickness over the upper fish-beds, though i was far from reaching its superior layers, which are buried here in the sea, to be rather more than five hundred feet. the fossiliferous beds occur a few hundred yards below the dwelling-house of rose farm. they are not quite uncovered in the ravine; but we find their places indicated by heaps of gray argillaceous shale, mingled with their characteristic ichthyolitic nodules, in one of which i found a small specimen of cheiracanthus. the projecting edge of some fossil-charged bed had been struck, mayhap, by an iceberg, and dashed into ruins, just as the subsiding land had brought the spot within reach of the attritive ice; and the broken heap thus detached had been shortly afterwards covered up, without mixture of any other deposit, by the red boulder-clay. on the previous day i had detected the fish-beds in another new locality,--one of the ravines of the lawn of cromarty house,--where the gray shale, concealed by a covering of soil and sward for centuries, had been laid bare during the storm by a swollen runnel, and a small nodule, inclosing a characteristic plate of pterichthys, washed out. and my next object in to-day's journey, after exploring this ravine of the boulder-clay, was to ascertain whether the beds did not also occur in a ravine of the parish of avoch, some eight or nine miles away, which, when lying a-bed one night in edinburgh, i remembered having crossed when a boy, at a point which lies considerably out of the ordinary route of the traveller. i had remarked on this occasion, as the resuscitated recollection intimated, that the precipices of the avoch ravine bore, at the unfrequented point, the peculiar aspect which i learned many years after to associate with the ichthyolitic member of the system; and i was now quite as curious to test the truth of a sort of vignette landscape, transferred to the mind at an immature period of life, and preserved in it for full thirty years, as desirous to extend my knowledge of the fossiliferous beds of a system to the elucidation of which i had peculiarly devoted myself. as the traveller reaches the flat moory uplands of the parish, where the water stagnates amid heath and moss over a thin layer of peaty soil, he finds the underlying boulder-clay, as shown in the chance sections, spotted and streaked with patches of a grayish-white. there is the same mixture of arenaceous and aluminous particles in the white as in the red portions of the mass; for, as we see so frequently exemplified in the spots and streaks of the red sandstone formations, whether old or new, the coloring matter has been discharged without any accompanying change of composition in the substance which it pervaded;--evidence enough that the red dye must be something distinct from the substance itself, just as the dye of a handkerchief is a thing distinct from the silk or cotton yarn of which the handkerchief has been woven. the stagnant water above, acidulated by its various vegetable solutions, seems to have been in some way connected with these appearances. in every case in which a crack through the clay gives access to the oozing moisture, we see the sides bleached, for several feet downwards, to nearly the color of pipe-clay; we find the surface, too, when it has been divested of the vegetable soil, presenting for yards together the appearance of sheets of half-bleached linen: the red ground of the clay has been acted upon by the percolating fluid, as the red ground of a bandanna handkerchief is acted upon through the openings in the perforated lead, by the discharging chloride of lime. the peculiar chemistry through which these changes are effected might be found, carefully studied, to throw much light on similar phenomena in the older formations. there are quarries in the new red sandstone in which almost every mass of stone presents a different shade of color from that of its neighboring mass, and quarries in the old red the strata of which we find streaked and spotted like pieces of calico. and their variegated aspect seems to have been communicated, in every instance, not during deposition, nor after they had been hardened into stone but when, like the boulder-clay, they existed in an intermediate state. be it remarked, too, that the red clay here,--evidently derived from the abrasion of the red rocks beneath,--is in dye and composition almost identical with the substance on which, as an unconsolidated sandstone, the bleaching influences, whatever their character, had operated in the palæozoic period, so many long ages before;--it is a repetition of the ancient experiment in the old red, that we now see going on in the boulder-clay. it is further worthy of notice, that the bleached lines of the clay exhibit, viewed horizontally, when the overlying vegetable mould has been removed, and the whitened surface in immediate contact with it paired off, a polygonal arrangement, like that assumed by the cracks in the bottom of clayey pools dried up in summer by the heat of the sun. can these possibly indicate the ancient rents and fissures of the boulder-clay, formed, immediately after the upheaval of the land, in the first process of drying, and remaining afterwards open enough to receive what the uncracked portions of the surface excluded,--the acidulated bleaching fluid? the kind of ferruginous pavement of the boulder-clay known to the agriculturist as _pan_, which may be found extending in some cases its iron cover over whole districts,--sealing them down to barrenness, as the iron and brass sealed down the stump of nebuchadnezzar's tree,--is, like the white strips and blotches of the deposit, worthy the careful notice of the geologist. it serves to throw some light on the origin of those continuous bands of clayey or arenaceous ironstone, which in the older formations in which vegetable matter abounds, whether oölitic or carboniferous, are of such common occurrence. the _pan_ is a stony stratum, scarcely less indurated in some localities than sandstone of the average hardness, that rests like a pavement on the surface of the boulder-clay, and that generally bears atop a thin layer of sterile soil, darkened by a russet covering of stunted heath. the binding cement of the _pan_ is, as i have said, ferruginous, and seems to have been derived from the vegetable covering above. of all plants, the heaths are found to contain most iron. nor is it difficult to conceive how, in comparatively flat tracts of heathy moor, where the surface water sinks to the stiff subsoil, and on which one generation of plants after another has been growing and decaying for many centuries, the minute metallic particles, disengaged in the process of decomposition, and carried down by the rains to the impermeable clay, should, by accumulating there, bind the layer on which they rest, as is the nature of ferruginous oxide, into a continuous stony crust. wherever this _pan_ occurs, we find the superincumbent soil doomed to barrenness,--arid and sun-baked during the summer and autumn months, and, from the same cause, overcharged with moisture in winter and spring. my friend mr. swanson, when schoolmaster of nigg, found a large garden attached to the school-house so inveterately sterile as to be scarce worth cultivation; a thin stratum of mould rested on a hard impermeable pavement of _pan_, through which not a single root could penetrate to the tenacious but not unkindly subsoil below. he set himself to work in his leisure hours, and bit by bit laid bare and broke up the pavement. the upper mould, long divorced from the clay on which it had once rested, was again united to it; the piece of ground began gradually to alter its character for the better; and when i last passed the way, i found it, though in a state of sad neglect, covered by a richer vegetation than it had ever borne under the more careful management of my friend. this ferruginous pavement of the boulder-clay may be deemed of interest to the geologist, as a curious instance of deposition in a dense medium, and as illustrative of the changes which may be effected on previously existing strata, through the agency of an overlying vegetation. i passed, on my way, through the ancient battle-field to which i have incidentally referred in the story of the miller of resolis.[ ] modern improvement has not yet marred it by the plough; and so it still bears on its brown surface many a swelling tumulus and flat oblong mound, and--where the high road of the district passes along its eastern edge--the huge gray cairn, raised, says tradition, over the body of an ancient pictish king. but the contest of which it was the scene belongs to a profoundly dark period, ere the gray dawn of scottish history began. as shown by the remains of ancient art occasionally dug up on the moor, it was a conflict of the times of the stone battle-axe, the flint arrow-head, and the unglazed sepulchral urn, unindebted for aught of its symmetry to the turning-lathe,--times when there were heroes in abundance, but no scribes. and the cairn, about a hundred feet in length and breadth, by about twenty in height, with its long hoary hair of overgrown lichen waving in the breeze, and the trailing club-moss shooting upwards from its base along its sides, bears in its every lineament full mark of its great age. it is a mound striding across the stream of centuries, to connect the past with the present. and yet, after all, what a mere matter of yesterday its extreme antiquity is! my explorations this morning bore reference to but the later eras of the geologist; the portion of the geologic volume which i was attempting to decipher and translate formed the few terminal paragraphs of its concluding chapter. and yet the _finis_ had been added to them for thousands of years ere this latter antiquity began. the boulder-clay had been formed and deposited; the land, in rising over the waves, had had many a huge pebble washed out of its last formed red stratum, or dropped upon it by ice-floes from above; and these pebbles lay mottling the surface of this barren moor for mile after mile, bleaching pale to the rains and the sun, as the meagre and mossy soil received, in the lapse of centuries, its slow accessions of organic matter, and darkened around them. and then, for a few brief hours, the heath, no longer solitary, became a wild scene of savage warfare,--of waving arms and threatening faces,--and of human lives violently spilled, gushing forth in blood; and, when all was over, the old weathered boulders were heaped up above the slain, and there began a new antiquity in relation to the pile in its gathered state, that bore reference to man's short lifetime, and to the recent introduction of the species. the child of a few summers speaks of the events of last year as long gone by; while his father advanced into middle life, regards them as still fresh and recent. i reached the burn of killein,--the scene of my purposed explorations,--where it bisects the inverness road; and struck down the rocky ravine, in the line of the descending strata and the falling streamlet, towards the point at which i had crossed it so many years before. first i passed along a thick bed of yellow stone,--next over a bed of stratified clay. "the little boy," i said, "took correct note of what he saw, though without special aim at the time, and as much under the guidance of a mere observative instinct as dame quickly, when she took note of the sea-coal fire, the round table, the parcel-gilt goblet, and goodwife keech's dish of prawns dressed in vinegar, as adjuncts of her interview with old sir john when he promised to marry her. these are unequivocally the ichthyolitic beds, whether they contain ichthyolites or no." the first nodule i laid open presented inside merely a pale oblong patch in the centre, which i examined in vain with the lens, though convinced of its organic origin, for a single scale. proceeding farther down the stream, i picked a nodule out of a second and lower bed, which contained more evidently its organism,--a finely-reticulated fragment, that at first sight reminded me of some delicate festinella of the silurian system. it proved, however, to be part of the tail of a cheiracanthus, exhibiting--what is rarely shown--the interior surfaces of those minute rectangular scales which in this genus lie over the caudal fin, ranged in right lines. a second nodule presented me with the spines of _diplacanthus striatus_; and still farther down the stream,--for the beds are numerous here, and occupy in vertical extent very considerable space in the system,--i detected a stratum of bulky nodules charged with fragments of coccosteus, belonging chiefly to two species,--_coccosteus decipiens_ and _coccosteus cuspidatus_. all the specimens bore conclusive evidence regarding the geologic place and character of the beds in which they occur; and in one of the number, a specimen of _coccosteus decipiens_, sufficiently fine to be transferred to my knapsack, and which now occupies its corner in my little collection, the head exhibits all its plates in their proper order, and the large dorsal plate, though dissociated from the nail-like attachment of the nape, presents its characteristic breadth entire. it was the plates of this species, first found in the flagstones of caithness, which were taken for those of a fresh-water tortoise; and hence apparently its specific name, _decipiens_;--it is the _deceiving_ coccosteus. i disinterred, in the course of my explorations, as many nodules as lay within reach,--now and then longing for a pickaxe, and a companion robust and persevering enough to employ it with effect; and after seeing all that was to be seen in the bed of the stream and the precipices, i retraced my steps up the dell to the highway. and then, striking off across the moor to the north,--ascending in the system as i climbed the eminence, which forms here the central ridge of the old maolbuie common,--i spent some little time in a quarry of pale red sandstone, known, from the moory height on which it has been opened, as the quarry of the maolbuie. but here, as elsewhere, the folds of that upper division of the lower old red in which it has been excavated contain nothing organic. why this should be so universally the case,--for in caithness, orkney, cromarty, and ross, wherever, in short, this member of the system is unequivocally developed, it is invariably barren of remains,--cannot, i suspect, be very satisfactorily explained. fossils occur both over and under it, in rocks that seem as little favorable to their preservation; but during that intervening period which its blank strata represent, at least the _species_ of all the ichthyolites of the system seem to have changed, and, so far as is yet known, the _genus_ coccosteus died out entirely. the black isle has been elaborately described in the last statistical account of the parish of avoch as comprising at least the analogues of three vast geologic systems. the great conglomerate, and the thick bed of coarse sandstone of corresponding character that lies over it, compose all which is not primary rock of that south-eastern ridge of the district which forms the shores of the moray frith; and _they_ are represented in the account as old red sandstone proper. then, next in order,--forming the base of a parallel ridge,--come those sandstone and argillaceous bands to which the ichthyolite beds belong; and these though at the time the work appeared their existence in the locality could be but guessed at, are described as representatives of the coal measures. last of all there occur those superior sandstones of the lower old red formation in which the quarry of the maolbuie has been opened, and which are largely developed in the central or _backbone_ ridge of the district. "and these," says the writer, "we have little hesitation in assigning to the _new_ red, or variegated sandstone formation." i remember that some thirteen years ago,--in part misled by authority, and in part really afraid to represent beds of such an enormous aggregate thickness as all belonging to one inconsiderable formation,--for such was the character of the old red sandstone at the time,--i ventured, though hesitatingly, and with less of detail, on a somewhat similar statement regarding the sandstone deposits of the parish of cromarty. but true it is, notwithstanding, that the stratified rocks of the black isle are composed generally, not of the analogues of three systems, but of merely a fractional portion of a single system,--a fact previously established in other parts of the district, and which my discovery of this day in the burn of killein served yet farther to confirm in relation to that middle portion of the tract in which the parish of avoch is situated. the geologic records, unlike the sybilline books, grow in volume and number as one pauses and hesitates over them; demanding, however, with every addition to their bulk, a larger and yet larger sum of epochs and of ages. the sun had got low in the western sky, and i had at least some eight or nine miles of rough road still before me; but the day had been a happy and not unsuccessful one, and so its hard work had failed to fatigue. the shadows, however, were falling brown and deep on the bleak maolbuie, as i passed, on my return, the solitary cairn; and it was dark night long ere i reached cromarty. next morning i quitted the town for the upper reaches of the frith, to examine yet further the superficial deposits and travelled boulders of the district. i landed at invergordon a little after noon, from the leith steamer, that, on its way to the upper ports of the moray and dingwall friths, stops at cromarty for passengers every wednesday; and then passing direct through the village, i took the western road which winds along the shore towards strathpeffer, skirting on the right the ancient province of the munroes. the day was clear and genial; and the wide-spreading woods of this part of the country, a little touched by their autumnal tints of brown and yellow, gave a warmth of hue to the landscape, which at an earlier season it wanted. a few slim streaks of semi-transparent mist, that barred the distant hill-peaks, and a few towering piles of intensely white cloud, that shot across the deep blue of the heavens, gave warning that the earlier part of the day was to be in all probability the better part of it, and that the harvest of observation which it was ultimately to yield might be found to depend on the prompt use made of the passing hour. what first attracts the attention of the geologist, in journeying westwards, is the altered color of the boulder-clay, as exhibited in ditches by the way-side, or along the shore. it no longer presents that characteristic red tint,--borrowed from the red sandstone beneath,--so prevalent over the black isle, and in easter ross generally; but is of a cold leaden hue, not unlike that which it wears above the coal measures of the south, or over the flagstones of caithness. the altered color here is evidently a consequence of the large development, in ferindonald and strathpeffer, of the ichthyolitic members of the old red, existing chiefly as fetid bituminous breccias and dark-colored sandstones: the boulder-clay of the locality forms the dressings, not of red, but of blackish-gray rocks; and, as almost everywhere else in scotland, its trail lies to the east of the strata, from which it was detached in the character of an impalpable mud by the age-protracted grindings of the denuding agent. it abounds in masses of bituminous breccia, some of which, of great size, seem to have been drifted direct from the valley of strathpeffer, and are identical in structure and composition with the rock in which the mineral springs of the strath have their rise, and to which they owe their peculiar qualities. after walking on for about eight miles, through noble woods and a lovely country, i struck from off the high road at the pretty little village of evanton, and pursued the course of the river auldgrande, first through intermingled fields and patches of copsewood, and then through a thick fir wood, to where the bed of the stream contracts from a boulder-strewed bottom of ample breadth, to a gloomy fissure, so deep and dark, that in many places the water cannot be seen, and so narrow, that the trees which shoot out from the opposite sides interlace their branches atop. large banks of the gray boulder-clay, laid open by the river, and charged with fragments of dingy sandstone and dark-colored breccia, testify, along the lower reaches of the stream, to the near neighborhood of the ichthyolitic member of the old red; but where the banks contract, we find only its lowest member, the great conglomerate. this last is by far the most picturesque member of the system,--abrupt and bold of outline in its hills, and mural in its precipices. and nowhere does it exhibit a wilder or more characteristic beauty than at the tall narrow portal of the auldgrande, where the river,--after wailing for miles in a pent-up channel, narrow as one of the lanes of old edinburgh, and hemmed in by walls quite as perpendicular, and nearly twice as lofty,--suddenly expands, first into a deep brown pool, and then into a broad tumbling stream, that, as if permanently affected in temper by the strict severity of the discipline to which its early life had been subjected, frets and chafes in all its after course, till it loses itself in the sea. the banks, ere we reach the opening of the chasm, have become steep, and wild, and densely wooded; and there stand out on either hand, giant crags, that plant their iron feet in the stream; here girdled with belts of rank succulent shrubs, that love the damp shade and the frequent drizzle of the spray; and there hollow and bare, with their round pebbles sticking out from the partially decomposed surface, like the piled-up skulls in the great underground cemetery of the parisians. massy trees, with their green fantastic roots rising high over the scanty soil, and forming many a labyrinthine recess for the frog, the toad, and the newt, stretch forth their gnarled arms athwart the stream. in front of the opening, with but a black deep pool between, there lies a midway bank of huge stones. of these, not a few of the more angular masses still bear, though sorely worn by the torrent, the mark of the blasting iron, and were evidently tumbled into the chasm from the fields above. but in the chasm there was no rest for them, and so the arrowy rush of the water in the confined channel swept them down till they dropped where they now lie, just where the widening bottom first served to dissipate the force of the current. and over the sullen pool in front we may see the stern pillars of the portal rising from eighty to a hundred feet in height, and scarce twelve feet apart, like the massive obelisks of some egyptian temple; while, in gloomy vista within, projection starts out beyond projection, like column beyond column in some narrow avenue of approach to luxor or carnac. the precipices are green, with some moss or byssus, that like the miner, chooses a subterranean habitat,--for here the rays of the sun never fall; the dead, mossy water beneath, from which the cliffs rise so abruptly, bears the hue of molten pitch; the trees, fast anchored in the rock, shoot out their branches across the opening, to form a thick tangled roof, at the height of a hundred and fifty feet overhead; while from the recesses within, where the eye fails to penetrate, there issues a combination of the strangest and wildest sounds ever yet produced by water: there is the deafening rush of the torrent, blent as if with the clang of hammers, the roar of vast bellows, and the confused gabble of a thousand voices. the sun, hastening to its setting, shone red, yet mellow, through the foliage of the wooded banks on the west, where, high above, they first curve from the sloping level of the fields, to bend over the stream; or fell more direct on the jutting cliffs and bosky dingles opposite, burnishing them as if with gold and fire; but all was coldly-hued at the bottom, where the torrent foamed gray and chill under the brown shadow of the banks; and where the narrow portal opened an untrodden way into the mysterious recesses beyond, the shadow deepened almost into blackness. the scene lacked but a ghost to render it perfect. an apparition walking from within like the genius in one of goldsmith's essays "along the surface of the water," would have completed it at once. laying hold of an overhanging branch, i warped myself upwards from the bed of the stream along the face of a precipice, and, reaching its sloping top, forced my way to the wood above, over a steep bank covered with tangled underwood, and a slim succulent herbage, that sickened for want of the sun. the yellow light was streaming through many a shaggy vista, as, threading my way along the narrow ravine as near the steep edge as the brokenness of the ground permitted, i reached a huge mass of travelled rock, that had been dropped in the old boulder period within a yard's length of the brink. it is composed of a characteristic granitic gneiss of a pale flesh-color, streaked with black, that, in the hand specimen, can scarce be distinguished from a true granite, but which, viewed in the mass, presents, in the arrangement of its intensely dark mica, evident marks of stratification, and which is remarkable, among other things, for furnishing almost all the very large boulders of this part of the country. unlike many of the granitic gneisses, it is a fine solid stone, and would cut well. when i had last the pleasure of spending a few hours with the late mr. william laidlaw, the trusted friend of sir walter scott, he intimated to me his intention,--pointing to a boulder of this species of gneiss,--of having it cut into two oblong pedestals, with which he purposed flanking the entrance to the mansion-house of the chief of the rosses,--the gentleman whose property he at that time superintended. it was, he said, both in appearance and history, the most remarkable stone on the lands of balnagown; and so he was desirous that it should be exhibited at balnagown castle to the best advantage. but as he fell shortly after into infirm health, and resigned his situation, i know not that he ever carried his purpose into effect. the boulder here, beside the chasm, measures about twelve feet in length and breadth, by from five to six in height, and contains from eight to nine hundred cubic feet of stone. on its upper table-like surface i found a few patches of moss and lichen, and a slim reddening tuft of the _vaccinium myrtillus_, still bearing, late as was the season, its half-dozen blaeberries. this pretty little plant occurs in great profusion along the steep edges of the auldgrande, where its delicate bushes, springing up amid long heath and ling, and crimsoned by the autumnal tinge, gave a peculiar warmth and richness this evening to those bosky spots under the brown trees, or in immediate contact with the dark chasm on which the sunlight fell most strongly; and on all the more perilous projections, i found the dark berries still shrivelling on their stems. thirty years earlier i would scarce have left them there; and the more perilous the crag on which they had grown, the more deliciously would they have eaten. but every period of life has its own playthings; and i was now chiefly engaged with the deep chasm and the huge boulder. chasm and boulder had come to have greatly more of interest to me than the delicate berries, or than even that sovereign dispeller of ennui and low spirits, an adventurous scramble among the cliffs. in what state did the chasm exist when the huge boulder,--detached, mayhap, at the close of a severe frost, from some island of the archipelago that is now the northern highlands of scotland,--was suffered to drop beside it, from some vast ice-floe drifting eastwards on the tide? in all probability merely as a fault in the conglomerate, similar to many of those faults which in the coal measures of the southern districts we find occupied by continuous dikes of trap. but in this northern region, where the trap-rocks are unknown, it must have been filled up with the boulder-clay, or with some still more ancient accumulation of debris. and when the land had risen, and the streams, swollen into rivers, flowed along the hollows which they now occupy, the loose rubbish would in the lapse of ages gradually wash downwards to the sea, as the stones thrown from the fields above were washed downwards in a later time; and thus the deep fissure would ultimately be cleared out. the boulder-stones lie thickly in this neighborhood, and over the eastern half of ross-shire, and the black isle generally; though for the last century they have been gradually disappearing from the more cultivated tracts on which there were fences or farm-steadings to be built, or where they obstructed the course of the plough. we found them occurring in every conceivable situation,--high on hill-sides, where the shepherd crouches beside them for shelter in a shower,--deep in the open sea, where they entangle the nets of the fisherman,--on inland moors, where in some remote age they were painfully rolled together, to form the druidical circle or picts'-house,--or on the margin of the coast, where they had been piled over one another at a later time, as protecting bulwarks against the encroachments of the waves. they lie strewed more sparingly over extended plains, or on exposed heights, than in hollows sheltered from the west by high land, where the current, when it dashed high on the hill-sides, must have been diverted from its easterly course, and revolved in whirling eddies. on the top of the fine bluff hill of fyrish, which i so admired to-day, each time i caught a glimpse of its purple front through the woods, and which shows how noble a mountain the old red sandstone may produce, the boulders lie but sparsely. i especially marked, however, when last on its summit, a ponderous traveller of a vividly green hornblende, resting on a bed of pale yellow sandstone, fully a thousand feet over the present high-water level. but towards the east, in what a seaman would term the _bight_ of the hill, the boulders have accumulated in vast numbers. they lie so closely piled along the course of the river alness, about half a mile above the village, that it is with difficulty the waters, when in flood, can force their passage through. for here, apparently, when the tide swept along the hill-side, many an ice-floe, detained in the shelter by the revolving eddy, dashed together in rude collision, and shook their stony burdens to the bottom. immediately to the east of the low promontory on which the town of cromarty is built there is another extensive accumulation of boulders, some of them of great size. they occupy exactly the place to which i have oftener than once seen the drift-ice of the upper part of the cromarty frith, set loose by a thaw, and then carried seawards by the retreating tide, forced back by a violent storm from, the east, and the fragments ground against each other into powder. and here, i doubt not, of old, when the sea stood greatly higher than now, and the ice-floes were immensely larger and more numerous than those formed, in the existing circumstances, in the upper shallows of the frith, would the fierce north-east have charged home with similar effect, and the broken masses have divested themselves of their boulders. the highland chieftain of one of our old gaelic traditions conversed with a boulder-stone, and told to it the story which he had sworn never to tell to man. i too, after a sort, have conversed with boulder-stones, not, however, to tell them any story of mine, but to urge them to tell theirs to me. but, lacking the fine ear of hans anderson, the danish poet, who can hear flowers and butterflies talk, and understand the language of birds, i have as yet succeeded in extracting from them no such articulate reply "as memnon's image, long renowned of old by fabling nilus, to the quivering touch of titan's ray, with each repulsive string consenting, sounded through the warbling air." and yet, who can doubt that, were they a little more communicative, their stories of movement in the past, with the additional circumstances connected with the places which they have occupied ever since they gave over travelling, would be exceedingly curious ones? among the boulder group to the east of cromarty, the most ponderous individual stands so exactly on the low-water line of our great lammas tides, that though its shoreward edge may be reached dry-shod from four to six times every twelvemonth, no one has ever succeeded in walking dry shod round it. i have seen a strong breeze from the west, prolonged for a few days, prevent its drying, when the lammas stream was at its point of lowest ebb, by from a foot to eighteen inches,--an indication, apparently, that to that height the waters of the atlantic may be heaped up against our shores by the impulsion of the wind. and the recurrence, during at least the last century, of certain ebbs each season, which, when no disturbing atmospheric phenomena interfere with their operation, are sure to lay it dry, demonstrate, that during that period no change, even the most minute, has taken place on our coasts, in the relative levels of sea and shore. the waves have considerably encroached, during even the last half-century, on the shores immediately opposite; but it must have been, as the stone shows, simply by the attrition of the waves, and the consequent lowering of the beach,--not through any rise in the ocean, or any depression of the land. the huge boulder here has been known for ages as the _clach malloch_, or accursed stone, from the circumstance, says tradition, that a boat was once wrecked upon it during a storm, and the boatmen drowned. though little more than seven feet in height, by about twelve in length, and some eight or nine in breadth, its situation on the extreme line of ebb imparts a peculiar character to the various productions, animal and vegetable, which we find adhering to it. they occur in zones, just as on lofty hills the botanist finds his agricultural, moorland, and alpine zones rising in succession as he ascends, the one over the other. at its base, where the tide rarely falls, we find two varieties of _lobularia digitata_, dead man's hand, the orange colored and the pale, with a species of sertularia; and the characteristic vegetable is the rough-stemmed tangle, or cuvy. in the zone immediately above the lowest, these productions disappear; the characteristic animal, if animal it be, is a flat yellow sponge,--the _halichondria papillaris_,--remarkable chiefly for its sharp siliceous spicula and its strong phosphoric smell; and the characteristic vegetable is the smooth-stemmed tangle, or queener. in yet another zone we find the common limpet and the vesicular kelp-weed; and the small gray balanus and serrated kelp-weed form the productions of the top. we may see exactly the same zones occurring in broad belts along the shore,--each zone indicative of a certain overlying depth of water; but it seems curious enough to find them all existing in succession on one boulder. of the boulder and its story, however, more in my next. chapter viii. imaginary autobiography of the _clach malloch_ boulder--its creation--its long night of unsummed centuries--laid open to light on a desert island--surrounded by an arctic vegetation--undermined by the rising sea--locked up and floated off on an ice-field--at rest on the sea-bottom--another night of unsummed years--the boulder raised again above the waves by the rising of the land--beholds an altered country--pine forests and mammals--another period of ages passes--the boulder again floated off by an iceberg--finally at rest on the shore of cromarty bay--time and occasion of naming it--strange phenomena accounted for by earthquakes--how the boulder of petty bay was moved--the boulder of auldgrande--the old highland paupers--the little parsi girl--her letter to her papa--but one human nature on earth--journey resumed--conon burying ground--an aged couple--gossip. the natural, and, if i may so speak, topographical, history of the _clach malloch_,--including, of course, its zoölogy and botany, with notes of those atmospheric effects on the tides, and of that stability for ages of the existing sea-level, which it indicates,--would of itself form one very interesting chapter: its geological history would furnish another. it would probably tell, if it once fairly broke silence and became autobiographical, first of a feverish dream of intense molten heat and overpowering pressure; and then of a busy time, in which the free molecules, as at once the materials and the artisans of the mass, began to build, each according to its nature, under the superintendence of a curious chemistry,--here forming sheets of black mica, there rhombs of a dark-green hornblende and a flesh-colored feldspar, yonder amorphous masses of a translucent quartz. it would add further, that at length, when the slow process was over, and the entire space had been occupied to the full by plate, molecule, and crystal, the red fiery twilight of the dream deepened into more than midnight gloom, and a chill unconscious night descended on the sleeper. the vast palæozoic period passes by,--the scarce less protracted secondary ages come to a close,--the eocene, miocene, pliocene epochs are ushered in and terminate,--races begin and end,--families and orders are born and die; but the dead, or those whose deep slumber admits not of dreams, take no note of time; and so it would tell how its long night of unsummed centuries seemed, like the long night of the grave, compressed into a moment. the marble silence is suddenly broken by the rush of an avalanche, that tears away the superincumbent masses, rolling them into the sea; and the ponderous block, laid open to the light, finds itself on the bleak shore of a desert island of the northern scottish archipelago, with a wintry scene of snow-covered peaks behind, and an ice-mottled ocean before. the winter passes, the cold severe spring comes on, and day after day the field-ice goes floating by,--now gray in shadow, now bright in the sun. at length vegetation, long repressed, bursts forth, but in no profuse luxuriance. a few dwarf birches unfold their leaves amid the rocks; a few sub-arctic willows hang out their catkins beside the swampy runnels; the golden potentilla opens its bright flowers on slopes where the evergreen _empetrum nigrum_ slowly ripens its glossy crow-berries; and from where the sea-spray dashes at full tide along the beach, to where the snow gleams at midsummer on the mountain-summits, the thin short sward is dotted by the minute cruciform stars of the scurvy-grass, and the crimson blossoms of the sea-pink. not a few of the plants of our existing sea-shores and of our loftier hill-tops are still identical in species; but wide zones of rich herbage, with many a fertile field and many a stately tree, intervene between the bare marine belts and the bleak insulated eminences; and thus the alpine, notwithstanding its identity with the littoral flora, has been long divorced from it; but in this early time the divorce had not yet taken place, nor for ages thereafter; and the same plants that sprang around the sea-margin rose also along the middle slopes to the mountain-summits. the landscape is treeless and bare, and a hoary lichen whitens the moors, and waves, as the years pass by, in pale tufts, from the disinterred stone, now covered with weather-stains, green and gray, and standing out in bold and yet bolder relief from the steep hill-side as the pulverizing frosts and washing rains bear away the lesser masses from around it. the sea is slowly rising, and the land, in proportion, narrowing its flatter margins, and yielding up its wider valleys to the tide; the low green island of one century forms the half-tide skerry, darkened with algæ, of another, and in yet a third exists but as a deep-sea rock. as its summit disappears, groups of hills, detached from the land, become islands, skerries, deep-sea rocks, in turn. at length the waves at full wash within a few yards of the granitic block. and now, yielding to the undermining influences, just as a blinding snow-shower is darkening the heavens, it comes thundering down the steep into the sea, where it lies immediately beneath the high-water line, surrounded by a wide float of pulverized ice, broken by the waves. a keen frost sets in; the half-fluid mass around is bound up for many acres into a solid raft, that clasps fast in its rigid embrace the rocky fragment; a stream-tide, heightened by a strong gale from the west, rises high on the beach; the consolidated ice-field moves, floats, is detached from the shore, creeps slowly outwards into the offing, bearing atop the boulder; and, finally, caught by the easterly current, it drifts away into the open ocean. and then, far from its original bed in the rock, amid the jerkings of a cockling sea, the mass breaks through the supporting float, and settles far beneath, amid the green and silent twilight of the bottom, where its mosses and lichens yield their place to stony encrustations of deep purple, and to miniature thickets of arboraceous zoöphites. the many-colored acalephæ float by; the many-armed sepiadæ shoot over; while shells that love the profounder depths,--the black modiola and delicate anomia,--anchor along the sides of the mass; and where thickets of the deep-sea tangle spread out their long, streamer-like fronds to the tide, the strong cyprina and many-ribbed astarte shelter by scores amid the reticulations of the short woody stems and thick-set roots. a sudden darkness comes on, like that which fell upon sinbad when the gigantic roc descended upon him; the sea-surface is fully sixty fathoms over head; but even at this great depth an enormous iceberg grates heavily against the bottom, crushing into fragments in its course, cyprina, modiola, astarte, with many a hapless mollusc besides; and furrows into deep grooves the very rocks on which they lie. it passes away; and, after many an unsummed year has also passed, there comes another change. the period of depression and of the boulder-clay is over. the water has shallowed as the sea-line gradually sank, or the land was propelled upwards by some elevatory process from below; and each time the tide falls, the huge boulder now raises over the waters its broad forehead, already hung round with flowing tresses of brown sea-weed, and looks at the adjacent coast. the country has strangely altered its features: it exists no longer as a broken archipelago, scantily covered by a semi-arctic vegetation, but as a continuous land, still whitened, where the great valleys open to the sea, by the pale gleam of local glaciers, and snow-streaked on its loftier hill-tops. but vast forests of dark pine sweep along its hill-sides or selvage its shores; and the sheltered hollows are enlivened by the lighter green of the oak, the ash, and the elm. human foot has not yet imprinted its sward; but its brute inhabitants have become numerous. the cream-colored coat of the wild bull,--a speck of white relieved against a ground of dingy green,--may be seen far amid the pines, and the long howl of the wolf heard from the nearer thickets. the gigantic elk raises himself from his lair, and tosses his ponderous horns at the sound; while the beaver, in some sequestered dell traversed by a streamlet, plunges alarmed into his deep coffer-dam, and, rising through the submerged opening of his cell, shelters safely within, beyond reach of pursuit. the great transverse valleys of the country, from its eastern to its western coasts, are still occupied by the sea,--they exist as broad ocean-sounds; and many of the detached hills rise around its shores as islands. the northern sutor forms a bluff high island, for the plains of easter ross are still submerged; and the black isle is in reality what in later times it is merely in name,--a sea-encircled district, holding a midway place between where the sound of the great caledonian valley and the sounds of the valleys of the conon and carron open into the german ocean. though the climate has greatly softened, it is still, as the local glaciers testify, ungenial and severe. winter protracts his stay through the later months of spring; and still, as of old, vast floats of ice, detached from the glaciers, or formed in the lakes and shallower estuaries of the interior, come drifting down the sounds every season, and disappear in the open sea, or lie stranded along the shores. ages have again passed: the huge boulder, from the further sinking of the waters, lies dry throughout the neaps, and is covered only at the height of each stream-tide; there is a float of ice stranded on the beach, which consolidates around it during the neap, and is floated off by the stream; and the boulder, borne in its midst, as of old, again sets out a voyaging. it has reached the narrow opening of the sutors, swept downwards by the strong ebb current, when a violent storm from the north-east sets in; and, constrained by antagonist forces,--the sweep of the tide on the one hand, and the roll of the waves on the other,--the ice-raft deflects into the little bay that lies to the east of the promontory now occupied by the town of cromarty. and there it tosses, with a hundred more jostling in rude collision; and at length bursting apart, the _clach malloch_, its journeyings forever over, settles on its final resting-place. in a period long posterior it saw the ultimate elevation of the land. who shall dare say how much more it witnessed, or decide that it did not form the centre of a rich forest vegetation, and that the ivy did not cling round it, and the wild rose shed its petals over it, when the dingwall, moray, and dornoch friths existed as sub-aërial valleys, traversed by streams that now enter the sea far apart, but then gathered themselves into one vast river, that, after it had received the tributary waters of the shin and the conon, the ness and the beauly, the helmsdale, the brora, the findhorn, and the spey, rolled on through the flat secondary formations of the outer moray frith,--lias, and oölite, and greensand, and chalk,--to fall into a gulf of the northern ocean which intervened between the coasts of scotland and norway, but closed nearly opposite the mouth of the tyne, leaving a broad level plain to connect the coasts of england with those of the continent! be this as it may, the present sea-coast became at length the common boundary of land and sea. and the boulder continued to exist for centuries still later as a nameless stone, on which the tall gray heron rested moveless and ghost-like in the evenings, and the seal at mid-day basked lazily in the sun. and then there came a night of fierce tempest, in which the agonizing cry of drowning men was heard along the shore. when the morning broke, there lay strewed around a few bloated corpses, and the fragments of a broken wreck; and amid wild execrations and loud sorrow the boulder received its name. such is the probable history, briefly told, because touched at merely a few detached points, of the huge _clach malloch_. the incident of the second voyage here is of course altogether imaginary, in relation to at least this special boulder; but it is to second voyages only that all our positive evidence testifies in the history of its class. the boulders of the st. lawrence, so well described by sir charles lyell, voyage by thousands every year;[ ] and there are few of my northern readers who have not heard of the short trip taken nearly half a century ago by the boulder of petty bay, in the neighborhood of culloden. a highland minister of the last century, in describing, for sir john sinclair's statistical account, a large sepulchral cairn in his parish, attributed its formation to an _earthquake_! earthquakes, in these latter times, are introduced, like the heathen gods of old, to bring authors out of difficulties. i do not think, however,--and i have the authority of the old critic for at least half the opinion,--that either gods or earthquakes should be resorted to by poets or geologists, without special occasion: they ought never to be called in except as a last resort, when there is no way of getting on without them. and i am afraid there have been few more gratuitous invocations of the earthquake than on a certain occasion, some five years ago, when it was employed by the inmate of a north-country manse, at once to account for the removal of the boulder-stone of petty bay, and to annihilate at a blow the geology of the free church editor of the _witness_. i had briefly stated in one of my papers, in referring to this curious incident, that the boulder of the bay had been "borne nearly three hundred yards outwards into the sea by an enclasping mass of ice, in the course of a single tide." "not at all," said the northern clergyman; "the cause assigned is wholly insufficient to produce such an effect. all the ice ever formed in the bay would be insufficient to remove such a boulder a distance, not of three hundred, but even of _three_ yards." the removal of the stone "_is referrible to an_ earthquake!" the country, it would seem, took a sudden lurch, and the stone tumbled off. it fell athwart the flat surface of the bay, as a soup tureen sometimes falls athwart the table of a storm-beset steamer, vastly to the discomfort of the passengers, and again caught the ground as the land righted. ingenious, certainly! it does appear a little wonderful, however, that in a shock so tremendous nothing should have fallen off except the stone. in an earthquake on an equally great scale, in the present unsettled state of society, endowed clergymen would, i am afraid, be in some danger of falling out of their charges. the boulder beside the auldgrande has not only, like the _clach malloch_, a geologic history of its own, but, what some may deem of perhaps equal authority, a _mythologic_ history also. the inaccessible chasm, impervious to the sun, and ever resounding the wild howl of the tortured water, was too remarkable an object to have escaped the notice of the old imaginative celts; and they have married it, as was their wont, to a set of stories quite as wild as itself. and the boulder, occupying a nearly central position in its course, just where the dell is deepest, and narrowest, and blackest, and where the stream bellows far underground in its wildest combination of tones, marks out the spot where the more extraordinary incidents have happened, and the stranger sights have been seen. immediately beside the stone there is what seems to be the beginning of a path leading down to the water; but it stops abruptly at a tree,--the last in the descent,--and the green and dewy rock sinks beyond for more than a hundred feet, perpendicular as a wall. it was at the abrupt termination of this path that a highlander once saw a beautiful child smiling and stretching out its little hand to him, as it hung half in air by a slender twig. but he well knew that it was no child, but an evil spirit, and that if he gave it the assistance which it seemed to crave, he would be pulled headlong into the chasm, and never heard of more. and the boulder still bears, it is said, on its side,--though i failed this evening to detect the mark,--the stamp, strangely impressed, of the household keys of balconie.[ ] the sun had now got as low upon the hill, and the ravine had grown as dark, as when, so long before, the lady of balconie took her last walk along the sides of the auldgrande; and i struck up for the little alpine bridge of a few undressed logs, which has been here thrown across the chasm, at the height of a hundred and thirty feet over the water. as i pressed through the thick underwood, i startled a strange-looking apparition in one of the open spaces beside the gulf, where, as shown by the profusion of plants of _vaccinium_, the blaeberries had greatly abounded in their season. it was that of an extremely old woman, cadaverously pale and miserable looking, with dotage glistening in her inexpressive, rheum-distilling eyes, and attired in a blue cloak, that had been homely when at its best, and was now exceedingly tattered. she had been poking with her crutch among the bushes, as if looking for berries; but my approach had alarmed her; and she stood muttering in gaelic what seemed, from the tones and repetition, to be a few deprecatory sentences. i addressed her in english, and inquired what could have brought to a place so wild and lonely, one so feeble and helpless. "poor object!" she muttered in reply,--"poor object!--very hungry;" but her scanty english could carry her no further. i slipped into her hand a small piece of silver, for which she overwhelmed me with thanks and blessings; and, bringing her to one of the broader avenues, traversed by a road which leads out of the wood, i saw her fairly entered upon the path in the right direction, and then, retracing my steps crossed the log-bridge. the old woman,--little, i should suppose from her appearance, under ninety,--was i doubt not, one of our ill-provided highland paupers, that starve under a law which, while it has dried up the genial streams of voluntary charity in the country and presses hard upon the means of the humbler classes, alleviates little, if at all, the sufferings of the extreme poor. amid present suffering and privation there had apparently mingled in her dotage some dream of early enjoyment,--a dream of the days when she had plucked berries, a little herd-girl, on the banks of the auldgrande; and the vision seemed to have sent her out, far advanced in her second childhood, to poke among the bushes with her crutch. my old friend the minister of alness,--uninstalled at the time in his new dwelling,--was residing in a house scarce half a mile from the chasm, to which he had removed from the parish manse at the disruption; and, availing myself of an invitation of long standing, i climbed the acclivity on which it stands, to pass the night with him. i found, however, that with part of his family, he had gone to spend a few weeks beside the mineral springs of strathpeffer, in the hope of recruiting a constitution greatly weakened by excessive labor, and that the entire household at home consisted of but two of the young ladies his daughters, and their ward, the little buchubai hormazdji. and who, asks the reader, is this buchubai hormazdji? a little parsi girl, in her eighth year, the daughter of a christian convert from the ancient faith of zoroaster, who now labors in the free church mission at bombay. buchubai, his only child, was on his conversion, forcibly taken from him by his relatives, but restored again by a british court of law; and he had secured her safety by sending her to europe, a voyage of many thousand miles, with a lady, the wife of one of our indian missionaries, to whom she had become attached, as her second but true mamma, and with whose sisters i now found her. the little girl, sadly in want of a companion this evening, was content, for lack of a better, to accept of me as a playfellow; and she showed me all her rich eastern dresses, and all her toys, and a very fine emerald, set in the oriental fashion, which, when she was in full costume, sparkled from her embroidered tiara. i found her exceedingly like little girls at home, save that she seemed more than ordinarily observant and intelligent,--a consequence mayhap, of that early development, physical and mental, which characterizes her race. she submitted to me, too, when i had got very much into her confidence, a letter she had written to her papa from strathpeffer, which was to be sent him by the next indian mail. and as it may serve to show that the style of little girls whose fathers were fire-worshippers for three thousand years and more differs in no perceptible quality from the style of little girls whose fathers in considerably less than three thousand were pagans, papists, and protestants by turns, besides passing through the various intermediate forms of belief, i must, after pledging the reader to strict secrecy, submit it to his perusal:-- "my dearest papa,--i hope you are quite well. i am visiting mamma at present at strathpeffer. she is much better now than when she was travelling. mamma's sisters give their love to you, and mamma, and mr. and mrs. f. also. they all ask you to pray for them, and they will pray also. there are a great many at water here for sick people to drink out of. the smell of the water is not at all nice. i sometimes drink it. give my dearest love to narsion skishadre, and tell her that i will write to her.--dearest papa," etc. it was a simple thought, which required no reach of mind whatever to grasp,--and yet an hour spent with little buchubai made it tell upon me more powerfully than ever before,--that there is in reality but one human nature on the face of the earth. had i simply read of buchubai hormazdji corresponding with her father hormazdji pestonji, and sending her dear love to her old companion narsion skishadre, the names so specifically different from those which we ourselves employ in designating our country folk, would probably have led me, through a false association, to regard the parties to which they attach as scarcely less specifically different from our country folk themselves. i suspect we are misled by associations of this kind when we descant on the peculiarities of race as interposing insurmountable barriers to the progress of improvement, physical or mental. we overlook, amid the diversities of form, color, and language, the specific identity of the human family. the celt, for instance, wants, it is said, those powers of sustained application which so remarkably distinguish the saxon; and so we agree on the expediency of getting rid of our poor highlanders by expatriation as soon as possible, and of converting their country into sheep-walks and hunting-parks. it would be surely well to have philosophy enough to remember what, simply through the exercise of a wise faith, the christian missionary never forgets, that the peculiarities of race are not specific and ineradicable, but mere induced habits and idiosyncracies engrafted on the stock of a common nature by accident of circumstance or development; and that, as they have been wrought into the original tissue through the protracted operation of one set of causes, the operation of another and different set, wisely and perseveringly directed, could scarce fail to unravel and work them out again. they form no part of the inherent design of man's nature, but have merely stuck to it in its transmissive passage downwards and require to be brushed off. there was a time, some four thousand years ago, when celt and saxon were represented by but one man and his wife, with their children and their children's wives; and some sixteen or seventeen centuries earlier all the varieties of the species,--caucasian and negro, mongolian and malay,--lay close packed up in the world's single family. in short, buchubai's amusing prattle proved to me this evening no bad commentary on st. paul's sublime enunciation to the athenians, that god has "made of one blood all nations of men to dwell on all the face of the earth." i was amused to find that the little girl, who listened intently as i described to the young ladies all i had seen and knew of the auldgrande, had never before heard of a ghost, and could form no conception of one now. the ladies explained, described, defined; carefully guarding all they said, however, by stern disclaimers against the ghost theory altogether, but apparently to little purpose. at length buchubai exclaimed, that she now knew what they meant, and that she herself had seen a great many ghosts in india. on explanation, however, her ghosts, though quite frightful enough, turned out to be not at all spiritual: they were things of common occurrence in the land she had come from,--exposed bodies of the dead. next morning--as the white clouds and thin mist-streaks of the preceding day had fairly foretold--was close and wet; and the long trail of vapor which rises from the chasm of the auldgrande in such weather, and is known to the people of the neighborhood as the "smoke of the lady's baking," hung, snake-like, over the river. about two o'clock the rain ceased, hesitatingly and doubtfully, however, as if it did not quite know its own mind; and there arose no breeze to shake the dank grass, or to dissipate the thin mist-wreath that continued to float over the river under a sky of deep gray. but the ladies, with buchubai, impatient to join their friends at strathpeffer, determined on journeying notwithstanding; and, availing myself of their company and their vehicle, i travelled on with them to dingwall, where we parted. i had purposed exploring the gray dingy sandstones and fetid breccias developed along the shores on the northern side of the bay, about two miles from the town, and on the sloping acclivities between the mansion-houses of tulloch and fowlis; but the day was still unfavorable, and the sections seemed untemptingly indifferent; besides, i could entertain no doubt that the dingy beds here are identical in place with those of cadboll on the coast of easter ross, which they closely resemble, and which alternate with the lower ichthyolitic beds of the old red sandstone; and so, for the present at least, i gave up my intention of exploring them. in the evening, the sun, far gone down towards its place of setting, burst forth in great beauty; and, under the influence of a kindly breeze from the west, just strong enough to shake the wet leaves, the sky flung off its thick mantle of gray. i sauntered out along the high-road, in the direction of my old haunts at conon-side, with, however, no intention of walking so far. but the reaches of the river, a little in flood, shone temptingly through the dank foliage, and the cottages under the conon woods glittered clear on their sweeping hill-side, "looking cheerily out" into the landscape; and so i wandered on and on, over the bridge, and along the river, and through the pleasure grounds of conon-house, till i found myself in the old solitary burying-ground beside the conon, which, when last in this part of the country, i was prevented from visiting by the swollen waters. the rich yellow light streamed through the interstices of the tall hedge of forest-trees that encircles the eminence, once an island, and fell in fantastic patches on the gray tombstone and the graves. the ruinous little chapel in the corner, whose walls a quarter of a century before i had distinctly traced, had sunk into a green mound; and there remained over the sward but the arch-stone of a gothic window, with a portion of the moulded transom attached, to indicate the character and style of the vanished building. the old dial-stone, with the wasted gnomon, has also disappeared; and the few bright-colored _throch-stanes_, raw from the chisel, that had been added of late years to the group of older standing, did not quite make up for what time in the same period had withdrawn. one of the newer inscriptions, however, recorded a curious fact. when i had resided in this part of the country so long before, there was an aged couple in the neighborhood, who had lived together, it was said, as man and wife, for more than sixty years: and now, here was their tombstone and epitaph. they had lived on long after my departure; and when, as the seasons passed, men and women whose births and baptisms had taken place since their wedding-day were falling around them well stricken in years, death seemed to have forgotten _them_; and when he came at last, their united ages made up well nigh two centuries. the wife had seen her ninety-sixth and the husband his hundred and second birthday. it does not transcend the skill of the actuary to say how many thousand women must die under ninety-six for every one that reaches it, and how many tens of thousands of men must die under a hundred and two for every man who attains to an age so extraordinary; but he would require to get beyond his tables in order to reckon up the chances against the woman destined to attain to ninety-six being courted and married in early life by the man born to attain to a hundred and two. after enjoying a magnificent sunset on the banks of the conon, just where the scenery, exquisite throughout, is most delightful, i returned through the woods, and spent half an hour by the way in the cottage of a kindly-hearted woman, now considerably advanced in years, whom i had known, when she was in middle life, as the wife of one of the conon-side hinds, and who not unfrequently, when i was toiling at the mallet in the burning sun, hot and thirsty, and rather loosely knit for my work, had brought me--all she had to offer at the time--a draught of fresh whey. at first she seemed to have wholly forgotten both her kindness and the object of it. she well remembered my master, and another cromarty man who had been grievously injured, when undermining an old building, by the sudden fall of the erection; but she could bethink her of no third cromarty man whatever. "eh, sirs!" she at length exclaimed, "i daresay ye'll be just the sma' prentice laddie. weel, what will young folk no come out o'? they were amaist a' stout big men at the wark except yoursel'; an' you're now stouter and bigger than maist o' them. eh, sirs!--an' are ye still a mason?" "no; i have not wrought as a mason for the last fourteen years; but i have to work hard enough for all that." "weel, weel, it's our appointed lot; an' if we have but health an' strength, an' the wark to do, why should we repine?" once fairly entered on our talk together, we gossipped on till the night fell, giving and receiving information regarding our old acquaintances of a quarter of a century before; of whom we found that no inconsiderable proportion had already sunk in the stream in which eventually we must all disappear. and then, taking leave of the kindly old woman, i walked on in the dark to dingwall, where i spent the night. i could fain have called by the way on my old friend and brother-workman, mr. urquhart,--of a very numerous party of mechanics employed at conon-side in the year the only individual now resident in this part of the country; but the lateness of the hour forbade. next morning i returned by the conon road, as far as the noble old bridge which strides across the stream at the village, and which has done so much to banish the water-wraith from the fords; and then striking off to the right, i crossed, by a path comparatively little frequented, the insulated group of hills which separates the valley of the conon from that of the peffer. the day was mild and pleasant, and the atmosphere clear; but the higher hills again exhibited their ominous belts of vapor, and there had been a slight frost during the night,--at this autumnal season the almost certain precursor of rain. chapter ix. the great conglomerate--its undulatory and rectilinear members--knock farril and its vitrified fort--the old highlanders an observant race--the vein of silver--summit of knock farril--mode of accounting for the luxuriance of herbage in the ancient scottish fortalices--the green graves of culloden--theories respecting the vitrification of the hill-forts--combined theories of williams and mackenzie probably give the correct account--the author's explanation--transformations of fused rocks--strathpeffer--the spa--permanent odoriferous qualities of an ancient sea-bottom converted into rock--mineral springs of the spa--infusion of the powdered rock a substitute--belemnite water--the lively young lady's comments--a befogged country seen from a hill-top--ben-wevis--journey to evanton--a geologist's night-mare--the route home--ruins of craighouse--incompatibility of tea and ghosts--end of the tour. i was once more on the great conglomerate,--here, as elsewhere, a picturesque, boldly-featured deposit, traversed by narrow, mural-sided valleys, and tempested by bluff abrupt eminences. its hills are greatly less confluent than those of most of the other sedimentary formations of scotland; and their insulated summits, recommended by their steep sides and limited areas to the old savage vaubans of the highlands, furnished, ere the historic eras began, sites for not a few of the ancient hill-forts of the country. the vitrified fort of craig phadrig, of the ord hill of kessock, and of knock farril,--two of the number, the first and last, being the most celebrated erections of their kind in the north of scotland,--were all formed on hills of the great conglomerate. the conglomerate exists here as a sort of miniature highlands, set down at the northern side of a large angular bay of palæozoic rock, which indents the _true_ highlands of the country, and which exhibits in its central area a prolongation of the long moory ridge of the black isle, formed, as i have already had occasion to remark, of an _upper_ deposit of the same lower division of the old red,--a deposit as noticeable for affecting a confluent, rectilinear character in its elevations, as the conglomerate is remarkable for exhibiting a detached and undulatory one. exactly the same features are presented by the same deposits in the neighborhood of inverness; the _undulatory_ conglomerate composing, to the north and west of the town, the picturesque wavy ridge comprising the twin-eminences of munlochy bay, the ord hill of kessock, craig phadrig, and the fir-covered hill beyond in the line of the great valley; while on the south and east the _rectilinear_ ichthyolitic member of the system, with the arenaceous beds that lie over it, form the continuous straight-lined ridge which runs on from beyond the moor of the leys to beyond the moor of culloden. there is a pretty little loch in this dwarf highlands of the brahan district, into which the old celtic prophet kenneth ore, when, like prospero, he relinquished his art, buried "deep beyond plummet sound" the magic stone in which he was wont to see the distant and the future. and with the loch it contains a narrow, hermit-like dell, bearing but a single row of fields, and these of small size, along its flat bottom, and whose steep gray sides of rustic conglomerate resemble cyclopean walls. it, besides, includes among its hills the steep hill of knock farril, which, rising bluff and bold immediately over the southern slopes of strathpeffer, adds so greatly to the beauty of the valley, and bears atop perhaps the finest specimen of the vitrified fort in scotland; and the bold frontage of cliff presented by the group to the west, over the pleasure grounds of brahan, is, though on no very large scale, one of the most characteristic of the conglomerate formation which can be seen anywhere. it is formed of exactly such cliffs as the landscape gardener would make if he could,--cliffs with their rude prominent pebbles breaking the light over every square foot of surface, and furnishing footing, by their innumerable projections, to many a green tuft of moss, and many a sweet little flower. some of the masses, too, that have rolled down from the precipices among the brahan woods far below, and stand up, like the ruins of cottages, amid the trees, are of singular beauty,--worth all the imitation-ruins ever erected, and obnoxious to none of the disparaging associations which the mere show and make-believe of the artificial are sure always to awaken. whatever exhibited an aspect in any degree extraordinary was sure to attract the notice of the old highlanders,--an acutely observant race, however slightly developed their reflective powers; and the great natural objects which excited their attention we always find associated with some traditionary story. it is said that in the conglomerate cliffs above brahan, a retainer of the mackenzie, one of the smiths of the tribe, discovered a rich vein of silver, which he wrought by stealth, until he had filled one of the apartments of his cottage with bars and ingots. but the treasure, it is added, was betrayed by his own unfortunate vanity, to his chief, who hanged him in order to serve himself his heir; and no one since his death has proved ingenious enough to convert the rude rock into silver. years had, i found, wrought their changes amid the miniature highlands of the conglomerate. the sapplings of the straggling wood on the banks of loch ousy,--the pleasant little lake, or lochan rather, of this upland region,--that i remembered having seen scarce taller than myself, had shot into vigorous treehood; and the steep slopes of knock farril, which i had left covered with their dark screen of pine, were now thickly mottled over with half-decayed stumps, and bore that peculiarly barren aspect which tracts cleared of their wood so frequently assume in their transition state, when the plants that flourished in the shade have died out in consequence of the exposure, and plants that love the open air and the unbroken sunshine have not yet sprung up in their place. i found the southern acclivities of the hill covered with scattered masses of vitrified stone, that had fallen from the fortalice atop; and would recommend to the collector in quest of a characteristic specimen, that instead of laboring, to the general detriment of the pile, in detaching one from the walls above, he should set himself to seek one here. the blocks, uninjured by the hammer, exhibit, in most cases, the angular character of the original fragments better than those forcibly detached from the mass, and preserve in fine keeping those hollower interstices which were but partially filled with the molten matter, and which, when shattered by a blow, break through and lose their character. one may spend an hour very agreeably on the green summit of knock farril. and at almost all seasons of the year a green summit it is,--greener considerably than any other hill-top in this part of the country. the more succulent grasses spring up rich and strong within the walls, here and there roughened by tufts of nettles, tall and rank, and somewhat perilous of approach,--witnesses, say the botanists, that man had once a dwelling in the immediate neighborhood. the green luxuriance which characterizes so many of the more ancient fortalices of scotland seems satisfactorily accounted for by dr. fleming, in his "zoölogy of the bass." "the summits and sides of those hills which were occupied by our ancestors as _hill-forts_," says the naturalist, "usually exhibit a far richer herbage than corresponding heights in the neighborhood with the mineral soil derived from the same source. it is to be kept in view, that these positions of strength were at the same time occupied as _hill-folds_, into which, during the threatened or actual invasion of the district by a hostile tribe, the cattle were driven, especially during the night, as to places of safety, and sent out to pasture in the neighborhood during the day. and the droppings of these collected herds would, as takes place in analogous cases at present, speedily improve the soil to such an extent as to induce a permanent fertility." the further instance adduced by the doctor, in showing through what protracted periods causes transitory in themselves may remain palpably influential in their effects, is curiously suggestive of the old metaphysical idea, that as every effect has its cause, "recurring from cause to cause up to the abyss of eternity, so every cause has also its effects, linked forward in succession to the end of time." on the bleak moor of culloden the graves of the slain still exist as patches of green sward, surrounded by a brown groundwork of stunted heather. the animal matter,--once the nerves, muscles, and sinews of brave men,--which originated the change, must have been wholly dissipated ages ago. but the effect once produced has so decidedly maintained itself, that it remains not less distinctly stamped upon the heath in the present day than it could have been in the middle of the last century, only a few years after the battle had been stricken. the vitrification of the rampart which on every side incloses the grassy area has been more variously, but less satisfactorily, accounted for than the green luxuriance within. it was held by pennant to be an effect of volcanic fire, and that the walls of this and all our other vitrified strongholds are simply the crater-rims of extinct volcanoes,--a hypothesis wholly as untenable in reference to the hill-forts as to the lime-kilns of the country: the vitrified forts are as little volcanic as the vitrified kilns. williams, the author of the "mineral kingdom," and one of our earlier british geologists, after deciding, on data which his peculiar pursuits enabled him to collect and weigh, that they are _not_ volcanic, broached the theory, still prevalent, as their name testifies, that they are artificial structures, in which vitrescency was designedly induced, in order to cement into solid masses accumulations of loose materials. lord woodhouselee advocated an opposite view. resting on the fact that the vitrification is but of partial occurrence, be held that it had been produced, not of design by the builders of the forts, but in the process of their demolition by a besieging enemy, who, finding, as he premised, a large portion of the ramparts composed of wood, had succeeded in setting them on fire. this hypothesis, however, seems quite as untenable as that of pennant. fires not unfrequently occur in cities, among crowded groups of houses, where walls of stone are surrounded by a much greater profusion of dry woodwork than could possibly have entered into the composition of the ramparts of a hill-fort; but who ever saw, after a city fire, masses of wall from eight to ten feet in thickness fused throughout? the sandstone columns of the aisles of the old greyfriars in edinburgh, surrounded by the woodwork of the galleries, the flooring, the seating, and the roof, were wasted, during the fire which destroyed the pile, into mere skeletons of their former selves; but though originally not more than three feet in diameter, they exhibited no marks of vitrescency. and it does not seem in the least probable that the stonework of the knock farril rampart could, if surrounded by wood at all, have been surrounded by an amount equally great, in proportion to its mass, as that which enveloped the aisle-columns of the old greyfriars. the late sir george mackenzie of coul adopted yet a fourth view. he held that the vitrification is simply an effect of the ancient beacon-fires kindled to warn the country of an invading enemy. but how account, on this hypothesis, for ramparts continuous, as in the case of knock farril, all round the hill? a powerful fire long kept up might well fuse a heap of loose stones into a solid mass; the bonfire lighted on the summit of arthur seat in , to welcome the queen on her first visit to scotland, particularly fused numerous detached fragments of basalt, and imparted, in some spots to the depth of about half an inch, a vesicular structure to the solid rock beneath. but no fire, however powerful, could have constructed a rampart running without break for several hundred feet round an insulated hill-top. "to be satisfied," said sir george, "of the reason why the signal-fires should be kindled on or beside a heap of stones, we have only to imagine a gale of wind to have arisen when a fire was kindled on the bare ground. the fuel would be blown about and dispersed, to the great annoyance of those who attended. the plan for obviating the inconvenience thus occasioned which would occur most naturally and readily would be to raise a heap of stones, on either side of which the fire might be placed to windward; and to account for the vitrification appearing all round the area, it is only necessary to allow the inhabitants of the country to have had a system of signals. a fire at one end might denote something different from a fire at the other, or in some intermediate part. on some occasions two or more fires might be necessary, and sometimes a fire along the whole line. it cannot be doubted," he adds, "that the rampart was originally formed with as much regularity as the nature of the materials would allow, both in order to render it more durable, and to make it serve the purposes of defence." this, i am afraid, is still very unsatisfactory. a fire lighted along the entire line of a wall inclosing nearly an acre of area could not be other than a very attenuated, wire-drawn line of fire indeed, and could never possess strength enough to melt the ponderous mass of rampart beneath, as if it had been formed of wax or resin. a thousand loads of wood piled in a ring round the summit of knock farril, and set at once into a blaze, would wholly fail to affect the broad rampart below; and long ere even a thousand, or half a thousand, loads could have been cut down, collected, and fired, an invading enemy would have found time enough to moor his fleet and land his forces, and possess himself of the lower country. again, the unbroken continuity of the vitrified line militates against the signal-system theory. fire trod so closely upon the heels of fire, that the vitrescency induced by the one fire impinged on and mingled with the vitrescency induced by the others beside it. there is no other mode of accounting for the continuity of the fusion; and how could definite meanings possibly be attached to the various parts of a line so minutely graduated, that the centre of the fire kindled on any one graduation could be scarce ten feet apart from the centre of the fire kindled on any of its two neighboring graduations? even by day, the exact compartment which a fire occupied could not be distinguished, at the distance of half a mile, from its neighboring compartments, and not at all by night, at any distance, from even the compartments farthest removed from it. who, for instance, at the distance of a dozen miles or so, could tell whether the flame that shone out in the darkness, when all other objects around it were invisible, was kindled on the east or west end of an eminence little more than a hundred yards in length? nay, who could determine,--for such is the requirement of the hypothesis,--whether it rose from a compartment of the summit a hundred feet distant from its west or east end, or from a compartment merely ninety or a hundred and ten feet distant from it? the supposed signal system, added to the mere beacon hypothesis, is palpably untenable. the theory of williams, however, which is, i am inclined to think, the true one in the main, seems capable of being considerably modified and improved by the hypothesis of sir george. the hill-fort,--palpably the most primitive form of fortalice or stronghold originated in a mountainous country,--seems to constitute man's first essay towards neutralizing, by the art of fortification, the advantages of superior force on the side of an assailing enemy. it was found, on the discovery of new zealand, that the savage inhabitants had already learned to erect exactly such hill-forts amid the fastnesses of that country as those which were erected two thousand years earlier by the scottish aborigines amid the fastnesses of our own. nothing seems more probable, therefore, than that the forts of eminences such as craig phadrig and knock farril, originally mere inclosures of loose, uncemented stones, may belong to a period not less ancient than that of the first barbarous wars of scotland, when, though tribe battled with tribe in fierce warfare, like the red men of the west with their brethren ere the european had landed on their shores, navigation was yet in so immature a state in northern europe as to secure to them an exemption from foreign invasion. in an after age, however, when the roving vikings had become formidable, many of the eminences originally selected, from _their inaccessibility_, as sites for hill-forts, would come to be chosen, from _their prominence in the landscape_, as stations for beacon-fires. and of course the previously erected ramparts, higher always than the inclosed areas, would furnish on such hills the conspicuous points from which the fires could be best seen. let us suppose, then, that the rampart-crested eminence of knock farril, seen on every side for many miles, has become in the age of northern invasion one of the beacon-posts of the district, and that large fires, abundantly supplied with fuel by the woods of a forest-covered country, and blown at times into intense heat by the strong winds so frequent in that upper stratum of air into which the summit penetrates, have been kindled some six or eight times on some prominent point of the rampart, raised, mayhap, many centuries before. at first the heat has failed to tell on the stubborn quartz and feldspar which forms the preponderating material of the gneisses, granites, quartz rocks, and coarse conglomerate sandstones on which it has been brought to operate; but each fire throws down into the interstices a considerable amount of the fixed salt of the wood, till at length the heap has become charged with a strong flux; and then one powerful fire more, fanned to a white heat by a keen, dry breeze, reduces the whole into a semi-fluid mass. the same effects have been produced on the materials of the rampart by the beacon-fires and the alkali, that were produced, according to pliny, by the fires and the soda of the phoenician merchants storm-bound on the sands of the river belus. but the state of civilization in scotland at the time is not such as to permit of the discovery being followed up by similar results. the semi-savage guardians of the beacon wonder at the _accident_, as they well may; but those happy accidents in which the higher order of discoveries originate occur in only the ages of cultivated minds; and so they do not acquire from it the art of manufacturing glass. it could not fail being perceived, however, by intellects at all human, that the consolidation which the fires of one week, or month, or year, as the case happened, had effected on one portion of the wall, might be produced by the fires of another week, or month, or year, on another portion of it; that, in short, a loose incoherent rampart, easy of demolition, might be converted, through the newly-discovered process, into a rampart as solid and indestructible as the rock on which it rested. and so, in course of time, simply by shifting the beacon-fires, and bringing them to bear in succession on every part of the wall, knock farril, with many a similar eminence in the country, comes to exhibit its completely vitrified fort where there had been but a loosely-piled hill-fort before. it in no degree militates against this compound theory,--borrowed in part from williams and in part from sir george,--that there are detached vitrified masses to be found on eminences evidently never occupied by hill-forts; or that there are hill-forts on other eminences only partially fused, or hill-forts on many of the less commanding sites that bear about them no marks of fire at all. nothing can be more probable than that in the first class of cases we have eminences that had been selected as beacon-stations, which had not previously been occupied by hill-forts; and in the last, eminences that had been occupied by hill-forts which, from their want of prominence in the general landscape, had not been selected as beacon-stations. and in the intermediate class of cases we have probably ramparts that were only partially vitrified, because some want of fuel in the neighborhood had starved the customary fires, or because fires had to be less frequently kindled upon them than on the more important stations; or, finally, because these hill-forts, from some disadvantage of situation, were no longer used as places of strength, and so the beacon-keepers had no motive to attempt consolidating them throughout by the piecemeal application of the vitrifying agent. but the old highland mode of accounting for the present appearance of knock farril and its vitrified remains is perhaps, after all, quite as good in its way as any of the modes suggested by the philosophers.[ ] i spent some time, agreeably enough, beside the rude rampart of knock farril, in marking the various appearances exhibited by the fused and semi-fused materials of which it is composed,--the granites, gneisses, mica-schists, hornblendes, clay-slates, and red sandstones of the locality. one piece of rock, containing much lime, i found resolved into a yellow opaque substance, not unlike the coarse earthenware used in the making of ginger-beer bottles; but though it had been so completely molten that it had dropped into a hollow beneath in long viscid trails, it did not contain a single air-vesicle; while another specimen, apparently a piece of fused mica-schist, was so filled with air-cells, that the dividing partitions were scarcely the tenth of a line in thickness. i found bits of schistose gneiss resolved into green glass; the old red sandstone basis of the conglomerate, which forms the hill, into a semi-metallic scoria, like that of an iron-smelter's furnace; mica into a gray, waxy-looking stone, that scratched glass; and pure white quartz into porcellanic trails of white, that ran in one instance along the face of a darker-colored rock below, like streaks of cream along the sides of a burnt china jug. in one mass of pale large-grained granite i found that the feldspar, though it had acquired a vitreous gloss on the surface, still retained its peculiar rhomboidal cleavage; while the less stubborn quartz around it had become scarce less vesicular and light than a piece of pumice. on some of the other masses there was impressed, as if by a seal, the stamp of pieces of charcoal; and so sharply was the impression retained, that i could detect on the vitreous surface the mark of the yearly growths, and even of the medullary rays, of the wood. in breaking open some of the others, i detected fragments of the charcoal itself, which, hermetically locked up in the rock, had retained all its original carbon. these last reminded me of specimens not unfrequent among the trap-rocks of the carboniferous and oölitic systems. from an intrusive overlying wacke in the neighborhood of linlithgow i have derived for my collection pieces of carbonized wood in so complete a state of keeping, that under the microscope they exhibit unbroken all the characteristic reticulations of the coniferæ of the coal measures. i descended the hill, and, after joining my friends at strathpeffer,--buchubai hormazdji among the rest,--visited the spa, in the company of my old friend the minister of alness. the thorough identity of the powerful effluvium that fills the pump-room with that of a muddy sea-bottom laid bare in warm weather by the tide, is to the dweller on the sea-coast very striking. it _is_ identity,--not mere resemblance. in most cases the organic substances undergo great changes in the bowels of the earth. the animal matter of the caithness ichthyolites exists, for instance, as a hard, black, insoluble bitumen, which i have used oftener than once as sealing-wax; the vegetable mould of the coal measures has been converted into a fire-clay, so altered in the organic pabulum, animal and vegetable, whence it derived its fertility, that, even when laid open for years to the meliorating effects of the weather and the visits of the winged seeds, it will not be found bearing a single spike or leaf of green. but here, in smell, at least, that ancient mud, swum over by the diplopterus and the diplacanthus, and in which the coccosteus and pterichthys burrowed, has undergone no change. the soft ooze has become solid rock, but its odoriferous qualities have remained unaltered. i next visited an excavation a few hundred yards on the upper side of the pump-room, in which the gray fetid breccia of the strath has been quarried for dyke-building, and examined the rock with some degree of care, without, however, detecting in it a single plate or scale. lying over that conglomerate member of the system which, rising high in the knock farril range, forms the southern boundary of the valley, it occupies the place of the lower ichthyolitic bed, so rich in organisms in various other parts of the country; but here the bed, after it had been deposited in thin horizontal laminæ, and had hardened into stone, seems to have been broken up, by some violent movement, into minute sharp-edged fragments, that, without wear or attrition, were again consolidated into the breccia which it now forms. and its ichthyolites, if not previously absorbed, were probably destroyed in the convulsion. detached scales and spines, however, if carefully sought for in the various openings of the valley, might still be found in the original laminæ of the fragments. they must have been amazingly abundant in it once; for so largely saturated is the rock with the organic matter into which they have been resolved, that, when struck by the hammer, the impalpable dust set loose sensibly affects the organs of taste, and appeals very strongly to those of smell. it is through this saturated rock that the mineral springs take their course. even the surface-waters of the valley, as they pass over it contract in a perceptible degree its peculiar taste and odor. with a little more time to spare, i would fain have made this breccia of the old red the subject of a few simple experiments. i would have ground it into powder, and tried upon it the effect both of cold and hot infusion. portions of the water are sometimes carried in casks and bottles, for the use of invalids, to a considerable distance; but it is quite possible that a little of the _rock_, to which the water owes its qualities, might, when treated in this way, have all the effects of a considerable quantity of the _spring_. it might be of some interest, too, to ascertain its qualities when crushed, as a soil, or its effect on other soils; whether, for instance, like the old sterile soils of the carboniferous period, it has lost, through its rock-change, the fertilizing properties which it once possessed; or whether it still retains them, like some of the coprolitic beds of the oölite and greensand, and might not, in consequence, be employed as a manure. a course of such experiments could scarce fail to furnish with agreeable occupation some of the numerous annual visitants of the spa, who have to linger long, with but little to engage them, waiting for what, if it once fairly leave a man, returns slowly, when it returns at all. in mentioning at the dinner-table of my friend my scheme of infusing rock in order to produce spa water, i referred to the circumstance that the belemnite of our liasic deposits, when ground into powder, imparts to boiling water a peculiar taste and smell, and that the infusion, taken in very small quantities, sensibly affects both palate and stomach. and i suggested that belemnite water, deemed sovereign of old, when the belemnite was regarded as a thunderbolt, in the cure of bewitched cattle, might be in reality medicinal, and that the ancient superstition might thus embody, as ancient superstitions not unfrequently do, a nucleus of fact. the charm, i said, might amount to no more than simply the administration of a medicine to sick cattle, that did harm in no case, and good at times. the lively comment of one of the young ladies on the remark amused us all. if an infusion of stone had cured, in the last age, cattle that were bewitched, the strathpeffer water, she argued, which was, it seems, but an infusion of stone, might cure cattle that were sick now; and so, though the biped patients of the strath could scarce fail to decrease when they knew that its infused stone contained but the strainings of old mud, and the juices of dead unsalted fish, it was gratifying to think that the poor spa might still continue to retain its patients, though of a lower order. the pump-room would be converted into a rustic, straw-thatched shed, to which long trains of sick cattle, affected by weak nerves and dyspepsia, would come streaming along the roads every morning and evening, to drink and gather strength. the following morning was wet and lowering, and a flat ceiling of gray cloud stretched across the valley, from the summit of the knock farril ridge of hills on the one side, to the lower flanks of ben-wevis on the other. i had purposed ascending this latter mountain,--the giant of the north-eastern coast, and one of the loftiest of our second-class scottish hills anywhere,--to ascertain the extreme upper line at which travelled boulders occur in this part of the country. but it was no morning for wading knee-deep through the trackless heather; and after waiting on, in the hope the weather might clear up, watching at a window the poorer invalids at the spa, as they dragged themselves through the rain to the water, i lost patience, and sallied out, beplaided and umbrellaed, to see from the top of knock farril how the country looked in a fog. at first, however, i saw much fog, but little country; but as the day wore on, the flat mist-ceiling rose together, till it rested on but the distant hills, and the more prominent features of the landscape began to stand out amid the more general gray, like the stronger lines and masses in a half-finished drawing, boldly dashed off in the neutral tint of the artist. the portions of the prospect generically distinct are, notwithstanding its great extent and variety, but few; and the partial veil of haze, by glazing down its distracting multiplicity of minor points, served to bring them out all the more distinctly. there is, first stretching far in a southern and eastern direction along the landscape, the rectilinear ridge of the black isle,--not quite the sort of line a painter would introduce into a composition, but true to geologic character. more in the foreground, in the same direction, there spreads a troubled cockling sea of the great conglomerate. turning to the north and west, the deep valley of strathpeffer, with its expanse of rich level fields, and in the midst its old baronial castle, surrounded by coeval trees of vast bulk, lies so immediately at the foot of the eminence, that i could hear in the calm the rush of the little stream, swollen to thrice its usual bulk by the rains of the night. beyond rose the thick-set ben-wevis,--a true gneiss mountain, with breadth enough of shoulders, and amplitude enough of base, to serve a mountain thrice as tall, but which, like all its cogeners of this ancient formation, was arrested in its second stage of growth, so that many of the slimmer granitic and porphyritic hills of the country look down upon it, as agamemnon, according to homer, looked down upon ulysses. "broad is his breast, his shoulders larger spread, though great atrides overtops his head." all around, as if topling, wave-like, over the outer edges of the comparatively flat area of palæozoic rock which composes the middle ground of the landscape, rose a multitude of primary hill-peaks, barely discernible in the haze; while the long withdrawing dingwall frith, stretching on towards the open sea for full twenty miles, and flanked on either side by ridges of sandstone, but guarded at the opening by two squat granitic columns, completed the prospect, by adding to its last great feature. all was gloomy and chill; and as i turned me down the descent, the thick wetting drizzle again came on; and the mist-wreaths, after creeping upwards along the hill-side, began again to creep down. when i had first visited the valley, more than a quarter of a century before, it was on a hot breathless day of early summer, in which, though the trees in fresh leaf seemed drooping in the sunshine, and the succulent luxuriance of the fields lay aslant, half-prostrated by the fierce heat, the rich blue of ben-wevis, far above, was thickly streaked with snow, on which it was luxury even to look. it gave one iced fancies, wherewithal to slake, amid the bright glow of summer, the thirst in the mind. the recollection came strongly upon me, as the fog from the hill-top closed dark behind, like that sung by the old blind englishman, which "o'er the marish glides, and gathers ground fast at the lab'rer's heel, homeward returning." but the contrast had nothing sad in it; and it was pleasant to feel that it had not. i had resigned many a baseless hope and many an idle desire since i had spent a vacant day amid the sunshine, now gazing on the broad placid features of the snow-streaked mountain; and now sauntering under the tall ancient woods, or along the heath-covered slopes of the valley; but in relation to never-tiring, inexhaustible nature, the heart was no fresher at that time than it was now. i had grown no older in my feelings or in my capacity of enjoyment; and what then was there to regret? i rode down the strath in an omnibus which plies between the spa and dingwall, and then walked on to the village of evanton, which i reached about an hour after nightfall, somewhat in the circumstances of the "damp stranger," who gave beau brummel the cold. there were, however, no beau brummels in the quiet village inn in which i passed the night, and so the effects of the damp were wholly confined to myself. i was soundly pummelled during the night by a frightful female, who first assumed the appearance of the miserable pauper woman whom i had seen beside the auldgrande, and then became the lady of balconie; and, though sufficiently indignant, and much inclined to resist, i could stir neither hand nor foot, but lay passively on my back, jambed fast behind the huge gneiss boulder and the edge of the gulf. and yet, by a strange duality of perception, i was conscious all the while that, having got wet on the previous day, i was now suffering from an attack of nightmare: and held that it would be no very serious matter even should the lady tumble me into the gulf, seeing that all would be well again when i awoke in the morning. dreams of this character, in which consciousness bears reference at once to the fictitious events of the vision and the real circumstances of the sleeper, must occupy, i am inclined to think, very little time,--single moments, mayhap, poised midway between the sleeping and waking state. next day (sunday) i attended the free church in the parish, where i found a numerous and attentive congregation,--descendants, in large part, of the old devout munroes of ferindonald,--and heard a good solid discourse. and on the following morning i crossed the sea at what is known as the fowlis ferry, to explore, on my homeward route, the rocks laid bare along the shore in the upper reaches of the frith. i found but little by the way: black patches of bitumen in the sandstone of one of the beds, with a bed of stratified clay, inclosing nodules, in which, however, i succeeded in detecting nothing organic; and a few fragments of clay-slate locked up in the red sandstone, sharp and unworn at their edges, as if derived from no great distance, though there be now no clay-slate in the eastern half of ross; but though the rocks here belong evidently to the ichthyolitic member of the old red, not a single fish, not a "nibble" even, repaid the patient search of half a day. i, however, passed some time agreeably enough among the ruins of craighouse. when i had last seen, many years before, this old castle,[ ] the upper stories were accessible; but they were now no longer so. time, and the little herdboys who occasionally shelter in its vaults, had been busy in the interval; and, by breaking off a few projecting corners by which the climber had held, and by effacing a few notches into which he had thrust his toe-points, they had rendered what had been merely difficult impracticable. i remarked that the huge kitchen chimney of the building,--a deep hollow recess which stretches across the entire gable, and in which, it is said, two thrashers once plied the flail for a whole winter,--bore less of the stain of recent smoke than it used to exhibit twenty years before; and inferred that there would be fewer wraith-lights seen from the castle at nights than in those days of _evil spirits_ and illicit stills, when the cottars in the neighborhood sent more smuggled whiskey to market than any equal number of the inhabitants of almost any other district in the north. it has been long alleged that there existed a close connection between the more ghostly spirits of the country and its distilled ones. "how do you account," said a north country minister of the last age (the late rev. mr. m'bean of alves) to a sagacious old elder of his session, "for the almost total disappearance of the ghosts and fairies that used to be so common in your young days?" "tak my word for 't, minister," replied the shrewd old man, "it's a' owing to the _tea_; when the _tea_ cam in, the ghaists an' fairies gaed out. weel do i mind when at a' our neeborly meetings,--bridals, christenings, lyke-wakes, an' the like,--we entertained ane anither wi' rich nappy ale; an' whan the verra dowiest o' us used to get warm i' the face, an' a little confused in the head, an' weel fit to see amaist onything whan on the muirs on our way hame. but the tea has put out the nappy; an' i have remarked, that by losing the nappy we lost baith ghaists an' fairies." quitting the ruin, i walked on along the shore, tracing the sandstone as i went, as it rises from lower to higher beds; and where it ceases to crop out at the surface, and gravel and the red boulder-clays take the place of rock, i struck up the hill, and, traversing the parishes of resolis and cromarty, got home early in the evening. i had seen and done scarcely half what i had intended seeing or doing: alas, that in reference to every walk which i have yet attempted to tread, this special statement should be so invariably true to fact!--alas, that all my full purposes, should be coupled with but half realizations! but i had at least the satisfaction, that though i had accomplished little, i had enjoyed much; and it is something, though not all, nor nearly all, that, since time is passing, it should pass happily. in my next chapter i shall enter on my tour to orkney. it dates one year earlier ( ) than the tour with which i have already occupied so many chapters; but i have thus inverted the order of _time_, by placing it last, that i may be able so to preserve the order of _space_ as to render the tract travelled over in my narrative continuous from edinburgh to the northern extremity of pomona. chapter x. recovered health--journey to the orkneys--aboard the steamer at wick--mr. bremner--masonry of the harbor of wick--the greatest blunders result from good rules misapplied--mr. bremner's theory about sea-washed masonry--singular fracture of the rock near wick--the author's mode of accounting for it--"simple but not obvious" thinking--mr. bremner's mode of making stone erections under water--his exploits in raising foundered vessels--aspect of the orkneys--- the ungracious schoolmaster--in the frith of kirkwall--cathedral of st. magnus--appearance of kirkwall--its "perished suppers"--its ancient palaces--blunder of the scotch aristocracy--the patronate wedge--breaking ground in orkney--minute gregarious coccosteus--true position of the coccosteus' eyes--ruins of one of cromwell's forts--antiquities of orkney--the cathedral--its sculptures--the mysterious cell--prospect from the tower--its chimes--ruins of castle patrick. a twelvemonth had gone by since a lingering indisposition, which bore heavily on the springs of life, compelled me to postpone a long-projected journey to the orkneys, and led me to visit, instead, rich level england, with its well-kept roads and smooth railways, along which the enfeebled invalid can travel far without fatigue. i had now got greatly stronger; and, if not quite up to my old thirty miles per day, nor altogether so bold a cragsman as i had been only a few years before, i was at least vigorous enough to enjoy a middling long walk, and to breast a tolerably steep hill. and so i resolved on at least glancing over, if not exploring, the fossiliferous deposits of the orkneys, trusting that an eye somewhat practised in the formations mainly developed in these islands might enable me to make some amends for seeing comparatively little, by seeing well. i took coach at invergordon for wick early in the morning of friday; and, after a weary ride, in a bleak gusty day, that sent the dust of the road whirling about the ears of the sorely-tossed "outsides," with whom i had taken my chance, i alighted in wick, at the inn-door, a little after six o'clock in the evening. the following morning was wet and dreary; and a tumbling sea, raised by the wind of the previous day and night, came rolling into the bay; but the waves bore with them no steamer; and when, some five hours after the expected time, she also came rolling in, her darkened and weather-beaten sides and rigging gave evidence that her passage from the south had been no holiday trip. impatient, however, of looking out upon the sea for hours, from under dripping eaves, and through the dimmed panes of streaming windows, i got aboard with about half-a-dozen other passengers; and while the wick goods were in the course of being transferred to two large boats alongside, we lay tossing in the open bay. the work of raising box and package was superintended by a tall elderly gentleman from the shore, peculiarly scotch in his appearance,--the steam company's agent for this part of the country. "that," said an acquaintance, pointing to the agent, "is a very extraordinary man,--in his own special walk, one of the most original-minded, and at the same time most thoroughly practical, you perhaps ever saw. that is mr. bremner of wick, known now all over britain for his success in raising foundered vessels, when every one else gives them up. in the lifting of vast weights, or the overcoming the _vis inertiæ_ of the hugest bodies, nothing ever baffles mr. bremner. but come, i must introduce you to him. he takes an interest in your peculiar science, and is familiar with your geological writings." i was accordingly introduced to mr. bremner, and passed, in his company the half-hour which we spent in the bay, in a way that made me wish the time doubled. i had been struck by the peculiar style of masonry employed in the harbor of wick, and by its rock-like strength. the gray ponderous stones of the flagstone series of which it is built, instead of being placed on their flatter beds, like common ashlar in a building, or horizontal strata in a quarry, are raised on end, like staves in a pail or barrel, so that at some little distance the work looks as if formed of upright piles or beams jambed fast together. i had learned that mr. bremner had been the builder, and adverted to the peculiarity of his style of building. "you have given a vertical tilt to your strata," i said: "most men would have preferred the horizontal position. it used to be regarded as one of the standing rules of my old profession, that the 'broad bed of a stone' is the best, and should be always laid 'below.'" "a good rule for the land," replied mr. bremner, "but no good rule for the sea. the greatest blunders are almost always perpetrated through the misapplication of good rules. on a coast like ours, where boulders of a ton weight are rolled about with every storm like pebbles, these stones, if placed on what a workman would term their best beds, would be scattered along the shore like sea-wrack, by the gales of a single winter. in setting aside the prejudice," continued mr. bremner, "that what is indisputably the best bed for a stone on dry land is also the best bed in the water on an exposed coast, i reasoned thus:--the surf that dashes along the beach in times of tempest, and that forms the enemy with which i have to contend, is not simply water, with an onward impetus communicated to it by the wind and tide, and a reäctive impetus in the opposite direction,--the effect of the backward rebound, and of its own weight, when raised by these propelling forces above its average level of surface. true, it is all this; but it is also something more. as its white breadth of foam indicates, it is a subtile mixture of water and _air_, with a powerful _upward_ action,--a consequence of the air struggling to effect its escape; and this upward action must be taken into account in our calculations, as certainly as the other and more generally recognized actions. in striking against a piece of building, this subtile mixture dashes through the interstices into the interior of the masonry, and, filling up all its cavities, has by its upward action, a tendency to _set the work afloat_. and the broader the beds of the stones, of course the more extensive are the surfaces which it has to act upon. one of these flat flags, ten feet by four, and a foot in thickness, would present to this upheaving force, if placed on end, a superficies of but _four_ square feet; whereas, if placed on its broader base, it would present to it a superficies of _forty_ square feet. obviously, then, with regard to this aërial upheaving force, that acts upon the masonry in a direction in which no precautions are usually adopted to bind it fast,--for the existence of the force itself is not taken into account,--the greater bed of the stone must be just ten times over a worse bed than its lesser one; and on a tempestuous foam-encircled coast such as ours, this aërial upheaving force is in reality, though the builder may not know it, one of the most formidable forces with which he had to deal. and so, on these principles, i ventured to set my stones on end,--on what was deemed their _worst_, not their _best_ beds,--wedging them all fast together, like staves in an anker; and there, to the scandal of all the old rules, are they fast wedged still, firm as a rock." it was no ordinary man that could have originated such reasonings on such a subject, or that could have thrown himself so boldly, and to such practical effect, on the conclusions to which they led. mr. bremner adverted, in the course of our conversation, to a singular appearance among the rocks a little to the east and south of the town of wick, that had not, he said, attracted the notice it deserved. the solid rock had been fractured by some tremendous blow, dealt to it externally at a considerable height over the sea-level, and its detached masses scattered about like the stones of an ill-built harbor broken up by a storm. the force, whatever its nature, had been enormously great. blocks of some thirty or forty tons weight had been torn from out the solid strata, and piled up in ruinous heaps, as if the compact precipice had been a piece of loose brickwork, or had been driven into each other, as if, instead of being composed of perhaps the hardest and toughest sedimentary rock in the country, they had been formed of sun-dried clay. "i brought," continued mr. bremner, "one of your itinerant geological lecturers to the spot, to get his opinion; but he could say nothing about the appearance: it was not in his books." "i suspect," i replied, "the phenomenon lies quite as much within your own province as within that of the geological lecturer. it is in all probability an illustration, on a large scale, of those floating forces with which you operate on your foundered vessels, joined to the forces, laterally exerted, by which you drag them towards the shore. when the sea stood higher, or the land lower, in the eras of the raised beaches, along what is now caithness, the abrupt mural precipices by which your coast here is skirted must have secured a very considerable depth of water up to the very edge of the land;--your coast-line must have resembled the side of a mole or wharf: and in that glacial period to which the thick deposit of boulder-clay immediately over your harbor yonder belongs, icebergs of very considerable size must not unfrequently have brushed the brows of your precipices. an iceberg from eighty to a hundred feet in thickness, and perhaps half a square mile in area, could not, in this old state of things, have come in contact with these cliffs without first catching the ground outside; and such an iceberg, propelled by a fierce storm from the north-east, could not fail to lend the cliff with which it came in collision a tremendous blow. you will find that your shattered precipice marks, in all probability, the scene of a collision of this character: some hard-headed iceberg must have set itself to run down the land, and got wrecked upon it for its pains." my theory, though made somewhat in the dark,--for i had no opportunity of seeing the broken precipice until after my return from orkney,--seemed to satisfy mr. bremner; nor, on a careful survey of the phenomenon, the solution of which it attempted, did i find occasion to modify or give it up. with just knowledge enough of mr. bremner's peculiar province to appreciate his views, i was much impressed by their broad and practical simplicity; and bethought me, as we conversed, that the character of the thinking, which, according to addison, forms the staple of all writings of genius, and which he defines as "simple but not obvious," is a character which equally applies to _all_ good thinking, whatever its special department. power rarely resides in ingenious complexities: it seems to eschew in every walk the elaborately attenuated and razor-edged mode of thinking,--the thinking akin to that of the old metaphysical poets,--and to select the broad and massive style. hercules, in all the representations of him which i have yet seen, is the _broad_ hercules. i was greatly struck by some of mr. bremner's views on deep-sea founding. he showed me how, by a series of simple, but certainly not obvious contrivances, which had a strong air of practicability about them, he could lay down his erection, course by course, inshore, in a floating caisson of peculiar construction, beginning a little beyond the low-ebb line, and warping out his work piecemeal, as it sank, till it had reached its proper place, in, if necessary, from ten to twelve fathoms water, where, on a bottom previously prepared for it by the diving-bell, he had means to make it take the ground exactly at the required line. the difficulty and vast expense of building altogether by the bell would be obviated, he said, by the contrivance, and a solidity given to the work otherwise impossible in the circumstances: the stones could be laid in his floating caisson with a care as deliberate as on the land. some of the anecdotes which he communicated to me on this occasion, connected with his numerous achievements in weighing up foundered vessels, or in floating off wrecked or stranded ones, were of singular interest; and i regretted that they should not be recorded in an autobiographical memoir. not a few of them were humorously told, and curiously illustrative of that general ignorance regarding the "strength of materials" in which the scientific world has been too strangely suffered to lie, in this the world's most mechanical age; so that what ought to be questions of strict calculation are subjected to the guessings of a mere common sense, far from adequate, in many cases, to their proper resolution. "i once raised a vessel," said mr. bremner,--"a large collier, chock-full of coal,--which an english projector had actually engaged to raise with huge bags of india rubber, inflated with air. but the bags, of course taxed far beyond their strength, collapsed or burst; and so, when i succeeded in bringing the vessel up, through the employment of more adequate means, i got not only ship and cargo, but also a great deal of good india rubber to boot." only a few months after i enjoyed the pleasure of this interview with the brindley of scotland, he was called south, to the achievement of his greatest feat in at least one special department,--a feat generally recognized and appreciated as the most herculean of its kind ever performed,--the raising and warping off of the great britain steamer from her perilous bed in the sand of an exposed bay on the coast of ireland. i was conscious of a feeling of sadness as, in parting with mr. bremner, i reflected, that a man so singularly gifted should have been suffered to reach a period of life very considerably advanced, in employments little suited to exert his extraordinary faculties, and which persons of the ordinary type could have performed as well. napoleon,--himself possessed of great genius,--could have estimated more adequately than our british rulers the value of such a man. had mr. bremner been born a frenchman, he would not now be the mere agent of a steam company, in a third-rate seaport town. the rain had ceased, but the evening was gloomy and chill; and the orcades, which, on clearing the caithness coast, came as fully in view as the haze permitted, were enveloped in an undress of cloud and spray, that showed off their flat low features to no advantage at all. the bold, picturesque hebrides look well in any weather; but the level orkney islands, impressed everywhere, on at least their eastern coasts, by the comparatively tame character borne by the old red flagstones, when undisturbed by trap or the primary rocks, demand the full-dress auxiliaries of bright sun and clear sky, to render their charms patent. then, however, in their sleek coats of emerald and purple, and surrounded by their blue sparkling sounds and seas, with here a long dark wall of rock, that casts its shadow over the breaking waves, and there a light fringe of sand and broken shells, they are, as i afterwards ascertained, not without their genuine beauties. but had they shared in the history of the neighboring shetland group, that, according to some of the older historians, were suffered to lie uninhabited for centuries after their first discovery, i would rather have been disposed to marvel this evening, not that they had been unappropriated so long, but that they had been appropriated at all. the late member for orkney, not yet unseated by his shetland opponent, was one of the passengers in the steamboat; and, with an elderly man, an ambitious schoolmaster, strongly marked by the peculiarities of the genuine dominie, who had introduced himself to him as a brother voyager, he was pacing the quarter-deck, evidently doing his best to exert, under an unintermittent hot-water _douche_ of queries, the patient courtesy of a member of parliament on a visit to his constituency. at length, however, the troubler quitted him, and took his stand immediately beside me; and, too sanguinely concluding that i might take the same kind of liberty with the schoolmaster that the schoolmaster had taken with the member, i addressed to him a simple query in turn. but i had mistaken my man; the schoolmaster permitted to unknown passengers in humble russet no such sort of familiarities as those permitted by the member; and so i met with a prompt rebuff, that at once set me down. i was evidently a big, forward lad, who had taken a liberty with the master. it is, i suspect, scarce possible for a man, unless naturally very superior, to live among boys for some twenty or thirty years, exerting over them all the while a despotic authority, without contracting those peculiarities of character which the master-spirits,--our scots, lambs, and goldsmiths,--have embalmed with such exquisite truth in our literature, and which have hitherto militated against the practical realization of those unexceptionable abstractions in behalf of the status and standing of the teacher of youth which have been originated by men less in the habit of looking about them than the poets. it is worth while remarking how invariably the strong common sense of the scotch people has run every scheme under water that, confounding the character of the "village schoolmaster" with that of the "village clergyman," would demand from the schoolmaster the clergyman's work. we crossed the opening of the pentland frith, with its white surges and dark boiling eddies, and saw its twin lighthouses rising tall and ghostly amid the fog on our lee. we then skirted the shores of south ronaldshay, of burra, of copinshay, and of deerness; and, after doubling moul head, and threading the sound which separates shapinshay from the mainland, we entered the frith of kirkwall, and caught, amid the uncertain light of the closing evening, our earliest glimpse of the ancient cathedral of st. magnus. it seems at first sight as if standing solitary, a huge hermit-like erection, at the bottom of a low bay,--for its humbler companions do not make themselves visible until we have entered the harbor by a mile or two more, when we begin to find that it occupies, not an uninhabited tract of shore, but the middle of a gray straggling town, nearly a mile in length. we had just light enough to show us, on landing, that the main thoroughfare of the place, very narrow and very crooked, had been laid out, ere the country beyond had got highways, or the proprietors carts and carriages, with an exclusive eye to the necessities of the foot-passenger,--that many of the older houses presented, as is common in our northern towns, their gables to the street, and had narrow slips of closes running down along their fronts,--and that as we receded from the harbor, a goodly portion of their number bore about them an air of respectability, long maintained, but now apparently touched by decay. i saw, in advance of one of the buildings, several vigorous-looking planes, about forty feet in height, which, fenced by tall houses in front and rear, and flanked by the tortuosities of the street, had apparently forgotten that they were in orkney, and had grown quite as well as the planes of public thoroughfares grow elsewhere. after an abortive attempt or two made in other quarters, i was successful in procuring lodgings for a few days in the house of a respectable widow lady of the place, where i found comfort and quiet on very moderate terms. the cast of faded gentility which attached to so many of the older houses of kirkwall,--remnants of a time when the wealthier udallers of the orkneys used to repair to their capital at the close of autumn, to while away in each other's society their dreary winters,--reminded me of the poet malcolm's "sketch of the borough,"--a portrait for which kirkwall is known to have sat,--and of the great revolution effected in its evening parties, when "tea and turn-out" yielded its place to "tea and turn-in." but the churchyard of the place, which i had seen, as i passed along, glimmering with all its tombstones in the uncertain light, was all that remained to represent those "great men of the burgh," who, according to the poet, used to "pop in on its card and dancing assemblies, about the eleventh hour, resplendent in top-boots and scarlet vests," or of its "suppression-of-vice sisterhood of moral old maids," who kept all their neighbors right by the terror of their tongues. i was somewhat in a mood, after my chill and hungry voyage, to recall with a hankering of regret the vision of its departed suppers, so luxuriously described in the "sketch,"--suppers at which "large rounds of boiled beef smothered in cabbage, smoked geese, mutton hams, roasts of pork, and dishes of dog-fish and of welsh rabbits melted in their own fat, were diluted by copious draughts of strong home-brewed ale, and etherealized by gigantic bowls of rum punch." but the past, which is not ours, who, alas, can recall! and, after discussing a juicy steak and a modest cup of tea, i found i could regard with the indifferency of a philosopher, the perished suppers of kirkwall. i quitted my lodgings for church next morning about three-quarters of an hour ere the service commenced; and, finding the doors shut, sauntered up the hill that rises immediately over the town. the thick gloomy weather had passed with the night; and a still, bright, clear-eyed sabbath looked cheerily down on green isle and blue sea. i was quite unprepared by any previous description, for the imposing assemblage of ancient buildings which kirkwall presents full in the foreground, when viewed from the road which ascends along this hilly slope to the uplands. so thickly are they massed together, that, seen from one special point of view, they seem a portion of some magnificent city in ruins,--some such city though in a widely different style of architecture, as palmyra or baalbec. the cathedral of st. magnus rises on the right, the castle-palace of earl patrick stuart on the left, the bishop's palace in the space between; and all three occupy sites so contiguous, that a distance of some two or three hundred yards abreast gives the proper angle for taking in the whole group at a glance. i know no such group elsewhere in scotland. the church and palace of linlithgow are in such close proximity, that, seen together, relieved against the blue gleam of their lake, they form one magnificent pile; but we have here a taller, and, notwithstanding its saxon plainness, a nobler church, than that of the southern burgh, and at least one palace more. and the associations connected with the church, and at least one of the palaces ascend to a remoter and more picturesque antiquity. the castle-palace of earl patrick dates from but the time of james the sixth; but in the palace of the bishop, old grim haco died, after his defeat at largs, "of grief," says buchanan, "for the loss of his army, and of a valiant youth his relation;" and in the ancient cathedral, his body, previous to its removal to norway, was interred for a winter. the church and palace belong to the obscure dawn of the national history, and were norwegian for centuries before they were scotch. as i was coming down the hill at a snail's pace, i was overtaken by a countryman on his way to church. "ye'll hae come," he said, addressing me, "wi' the great man last night?" "i came in the steamer," i replied, "with your member, mr. dundas." "o, aye," rejoined the man; "but i'm no sure he'll be our member next time. the voluntaries yonder, ye see," jerking his head, as he spoke, in the direction of the united secession chapel of the place, "are awfu' strong and unco radical; and the free kirk folk will soon be as bad as them. but i belong to the establishment; and i side wi' dundas." the aristocracy of scotland committed, i am afraid, a sad blunder when they attempted strengthening their influence as a class by seizing hold of the church patronages. they have fared somewhat like those sailors of ulysses who, in seeking to appropriate their master's wealth, let out the winds upon themselves; and there is now, in consequence, a perilous voyage and an uncertain landing before them. it was the patronate wedge that struck from off the scottish establishment at least nine-tenths of the dissenters of the kingdom,--its secession bodies, its relief body, and, finally, its free church denomination,--comprising in their aggregate amount a great and influential majority of the scotch people. our older dissenters,--a circumstance inevitable to their position as such,--have been thrown into the movement party: the free church, in her present transition state, sits loose to all the various political sections of the country; but her natural tendency is towards the movement party also; and already, in consequence, do our scottish aristocracy possess greatly less political influence in the kingdom of which they own almost all the soil, than that wielded by their brethren the irish and english aristocracy in their respective divisions of the empire. were the representation of england and ireland as liberal as that of scotland, and as little influenced by the aristocracy, conservatism, on the passing of the reform bill, might have taken leave of office for evermore. and yet neither the english nor irish are naturally so conservative as the scotch. the patronate wedge, like that appropriated by achan, has been disastrous to the people, for it has lost to them the great benefits of a religious establishment, and very great these are; but it threatens, as in the case of the sons of carmi of old, to work more serious evil to those by whom it was originally coveted,--"evil to themselves and all their house." as i approached the free church, a squat, sun-burned, carnal-minded "old wee wifie," who seemed passing towards the secession place of worship, after looking wistfully at my gray maud, and concluding for certain that i could not be other than a southland drover, came up to me, and asked, in a cautious whisper, "will ye be wantin' a coo?" i replied in the negative; and the wee wifie, after casting a jealous glance at a group of grave-featured free church folk in our immediate neighborhood, who would scarce have tolerated sabbath trading in a seceder, tucked up her little blue cloak over her head, and hied away to the chapel. in the free church pulpit i recognized an old friend, to whom i introduced myself at the close of the service, and by whom i was introduced, in turn, to several intelligent members of his session, to whose kindness i owed, on the following day, introductions to some of the less accessible curiosities of the place. i rose betimes on the morning of monday, that i might have leisure enough before me to see them all, and broke my first ground in orkney as a geologist in a quarry a few hundred yards to the south and east of the town. it is strange enough how frequently the explorer in the old red finds himself restricted in a locality to well nigh a single organism,--an effect, probably, of some gregarious instinct in the ancient fishes of this formation, similar to that which characterizes so many of the fishes of the present time, or of some peculiarity in their constitution, which made each choose for itself a peculiar habitat. in this quarry, though abounding in broken remains, i found scarce a single fragment which did not belong to an exceedingly minute species of coccosteus, of which my first specimen had been sent me a few years before by mr. robert dick, from the neighborhood of thurso, and which i at that time, judging from its general proportions, had set down as the young of the _coccosteus cuspidatus_. its apparent gregariousness, too, quite as marked at thurso as in this quarry, had assisted, on the strength of an obvious enough analogy, in leading to the conclusion. there are several species of the existing fish, well known on our coasts, that, though solitary when fully grown, are gregarious when young. the coal-fish, which as the sillock of a few inches in length congregates by thousands, but as the colum-saw of from two and a half to three feet is a solitary fish, forms a familiar instance; and i had inferred that the coccosteus, found solitary, in most instances, when at its full size, had, like the coal-fish, congregated in shoals when in a state of immaturity. but a more careful examination of the specimens leads me to conclude that this minute gregarious coccosteus, so abundant in this locality that its fragments thickly speckle the strata for hundreds of yards together--(in one instance i found the dorsal plates of four individuals crowded into a piece of flag barely six inches square)--was in reality a distinct species. though not more than one-fourth the size, measured linearly, of the _coccosteus decipiens_, its plates exhibit as many of those lines of increment which gave to the occipital buckler of the creature its tortoise-like appearance, and through which plates of the buckler species were at first mistaken for those of a chelonian, as are exhibited by plates of the larger kinds, with an area ten times as great; its tubercles, too, some of them of microscopic size, are as numerous;--evidences, i think,--when we take into account that in the bulkier species the lines and tubercles increased in number with the growth of the plates, and that, once formed, they seem never to have been affected by the subsequent enlargement of the creature,--that this ichthyolite was not an _immature_, but really a _miniature_ coccosteus. we may see on the plates of the full-grown coccosteus, as on the shells of bivalves, such as _cardium echinatum_, or on those of spiral univalves, such as _buccinum undatum_, the diminutive markings which they bore when the creature was young; and on the plates of this species we may detect a regular gradation of tubercles from the microscopic to the minute, as we may see on the plates of the larger kinds a regular gradation from the minute to the fall-sized. the average length of the dwarf coccosteus of thurso and kirkwall, taken from the snout to the pointed termination of the dorsal plate, ranges from one and a-half to two inches; its entire length from head to tail probably from three to four. it was from one of mr. dick's specimens of this species that i first determined the true position of the eyes of the coccosteus,--a position which some of my lately-found ichthyolites conclusively demonstrate, and which agassiz, in his restoration, deceived by ill-preserved specimens, has fixed at a point considerably more lateral and posterior, and where eyes would have been of greatly less use to the animal. about a field's breadth below this quarry of the _coccosteus minor_,--if i may take the liberty of extemporizing a name, until such time as some person better qualified furnishes the creature with a more characteristic one,--there are the remains, consisting of fosse and rampart, with a single cannon lying red and honeycombed amid the ruins, of one of cromwell's forts, built to protect the town against the assaults of an enemy from the sea. in the few and stormy years during which this ablest of british governors ruled over scotland, he seems to have exercised a singularly vigilant eye. the claims on his protection of even the remote kirkwall did not escape him. the antiquities of the burgh next engaged me; and, as became its dignity and importance, i began with the cathedral, a building imposing enough to rank among the most impressive of its class anywhere, but whose peculiar _setting_ in this remote northern country, joined to the associations of its early history with the scandinavian rollos, sigurds, einars, and hacos of our dingier chronicles, serve greatly to enhance its interest. it is a noble pile, built of a dark-tinted old red sandstone,--a stone which, though by much too sombre for adequately developing the elegancies of the grecian or roman architecture, to which a light delicate tone of color seems indispensable, harmonizes well with the massier and less florid styles of the gothic. the round arch of that ancient norman school which was at one time so generally recognized as saxon, prevails in the edifice, and marks out its older portions. a few of the arches present on their ringstones those characteristic toothed and zig-zag ornaments that are of not unfamiliar occurrence on the round squat doorways of the older parish churches of england; but by much the greater number exhibit merely a few rude mouldings, that bend over ponderous columns and massive capitals, unfretted by the tool of the carver. though of colossal magnificence, the exterior of the edifice yields in effect, as in all true gothic buildings,--for the gothic is greatest in what the grecian is least,--to the sombre sublimity of the interior. the nave, flanked by the dim deep aisles, and by a double row of smooth-stemmed gigantic columns, supporting each a double tier of ponderous arches, and the transepts, with their three tiers of small norman windows, and their bold semi-circular arcs, demurely gay with toothed or angular carvings, that speak of the days of rolf and torfeinar, are singularly fine,--far superior to aught else of the kind in scotland; and a happy accident has added greatly to their effect. a rare byssus,--the _byssus aeruginosa_ of linnæus,--the _leprasia aeruginosa_ of modern botanists,--one of those gloomy vegetables of the damp cave and dark mine whose true habitat is rather under than upon the earth, has crept over arch, and column, and broad bare wall, and given to well nigh the entire interior of the building a close-fitted lining of dark velvety green, which, like the attic rust of an ancient medal, forms an appropriate covering to the sculpturings which it enwraps without concealing, and harmonizes with at once the dim light and the antique architecture. where the sun streamed upon it, high over head, through the narrow windows above, it reminded me of a pall of rich green velvet. it seems subject, on some of the lower mouldings and damper recesses, especially amid the tombs and in the aisles, to a decomposing mildew, which eats into it in fantastic map-like lines of mingled black and gray, so resembling runic fret-work, that i had some difficulty in convincing myself that the tracery which it forms,--singularly appropriate to the architecture,--was not the effect of design. the choir and chancel of the edifice, which at the time of my visit were still employed as the parish church of kirkwall, and had become a "world too wide" for the shrunken congregation, are more modern and ornate than the nave and transepts; and the round arch gives place, in at least their windows, to the pointed one. but the unique consistency of the pile is scarce at all disturbed by this mixture of styles. it is truly wonderful how completely the forgotten architects of the darker ages contrived to avoid those gross offences against good taste and artistic feeling into which their successors of a greatly more enlightened time are continually falling. instead of idly courting ornament for its own sake, they must have had as their proposed object the production of some definite effect, or the development of some special sentiment. it was perhaps well for them, too, that they were not so overladen as our modern architects with the _learning_ of their profession. extensive knowledge requires great judgment to guide it. if that high genius which can impart its own homogeneous character to very various materials be wanting, the more multifarious a man's ideas become, the more is he in danger of straining after a heterogeneous patch-work excellence, which is but excellence in its components, and deformity as a whole. every new vista opened up to him on what has been produced in his art elsewhere presents to him merely a new avenue of error. his mind becomes a mere damaged kaleidoscope, full of little broken pieces of the fair and the exquisite, but devoid of that nicely reflective machinery which can alone cast the fragments into shapes of a chaste and harmonious beauty. judging from the sculptures of st. magnus, the stone-cutter seems to have had but an indifferent command of his trade in orkney, when there was a good deal known about it elsewhere. and yet the rudeness of his work here, much in keeping with the ponderous simplicity of the architecture, serves but to link on the pile to a more venerable antiquity, and speaks less of the inartificial than of the remote. i saw a grotesque hatchment high up among the arches, that, with the uncouth carvings below, served to throw some light on the introduction into ecclesiastical edifices of those ludicrous sculptures that seem so incongruously foreign to the proper use and character of such places. the painter had set himself, with, i doubt not, fair moral intent, to exhibit a skeleton wrapped up in a winding-sheet; but, like the unlucky artist immortalized by gifford, who proposed painting a lion, but produced merely a dog, his skill had failed in seconding his intentions, and, instead of achieving a death in a shroud, he had achieved but a monkey grinning in a towel. his contemporaries, however, unlike those of gifford's artist, do not seem to have found out the mistake, and so the betowelled monkey has come to hold a conspicuous place among the solemnities of the cathedral. it does not seem difficult to conceive how unintentional ludicrosities of this nature, introduced into ecclesiastical erections in ages too little critical to distinguish between what the workman had purposed doing and what he had done, might come to be regarded, in a less earnest but more knowing age, as precedents for the introduction of the intentionally comic and grotesque. innocent accidental monkeys in towels may have thus served to usher into serious neighborhoods monkeys in towels that were such with malice _prepense_. i was shown an opening in the masonry, rather more than a man's height from the floor, that marked where a square narrow cell, formed in the thickness of the wall, had been laid open a few years before. and in the cell there was found depending from the middle of the roof a rusty iron chain, with a bit of barley-bread attached. what could the chain and bit of bread have meant? had they dangled in the remote past over some northern ugolino? or did they form in their dark narrow cell, without air-hole or outlet, merely some of the reserve terrors of the cathedral, efficient in bending to the authority of the church the rebellious monk or refractory nun? ere quitting the building, i scaled the great tower,--considerably less tall, it is said, than its predecessor, which was destroyed by lightning about two hundred years ago, but quite tall enough to command an extensive, and, though bare, not unimpressive prospect. two arms of the sea, that cut so deeply into the mainland on its opposite sides as to narrow it into a flat neck little more than a mile and a half in breadth, stretch away in long vista, the one to the south, and the other to the north; and so immediately is the cathedral perched on the isthmus between, as to be nearly equally conspicuous from both. it forms in each, to the inward-bound vessel, the terminal object in the landscape. there was not much to admire in the town immediately beneath, with its roofs of gray slate,--almost the only parts of it visible from this point of view,--and its bare treeless suburbs; nor yet in the tract of mingled hill and moor on either hand, into which the island expands from the narrow neck, like the two ends of a sand-glass; but the long withdrawing ocean-avenues between, that seemed approaching from south and north to kiss the feet of the proud cathedral,--avenues here and there enlivened on their ground of deep blue by a sail, and fringed on the lee--for the wind blew freshly in the clear sunshine--with their border of dazzling white, were objects worth while climbing the tower to see. ere my descent, my guide hammered out of the tower-bells, on my special behalf, somewhat, i daresay, to the astonishment of the burghers below, a set of chimes handed down entire, in all the notes, from the times of the monks, from which also the four fine bells of the cathedral have descended as an heirloom to the burgh. the chimes would have delighted the heart of old lisle bowles, the poet of "well-tun'd bell's enchanting harmony." i could, however, have preferred listening to their music, though it seemed really very sweet, a few hundred yards further away; and the quiet clerical poet,--the restorer of the sonnet in england, would, i doubt not, have been of the same mind. the oft-recurring tones of those bells that ring throughout his verse, and to which byron wickedly proposed adding a _cap_, form but an ingredient of the poetry in which he describes them; and they are represented always as distant tones, that, while they mingle with the softer harmonies of nature, never overpower them. "how sweet the tuneful bells responsive peal! * * * * * and, hark! with lessening cadence now they fall, and now, along the white and level tide they fling their melancholy music wide! bidding me many a tender thought recall of happy hours departed, and those years when, from an antique tower, ere life's fair prime, the mournful mazes of their mingling chime first wak'd my wondering childhood into tears!" from the cathedral i passed to the mansion of old earl patrick,--a stately ruin, in the more ornate castellated style of the sixteenth century. it stands in the middle of a dense thicket of what are _trying_ to be trees, and have so far succeeded, that they conceal, on one of the sides, the lower story of the building, and rise over the _spring_ of the large richly-decorated turrets. these last form so much nearer the base of the edifice than is common in our old castles, that they exhibit the appearance rather of hanging towers than of turrets,--of towers with their foundations cut away. the projecting windows, with their deep mouldings, square mullions, and cruciform shot-holes, are rich specimens of their peculiar style; and, with the double-windowed turrets with which they range, they communicate a sort of _high-relief_ effect to the entire erection, "the exterior proportions and ornaments of which," says sir walter scott, in his journal, "are very handsome." though a roofless and broken ruin, with the rank grass waving on its walls, it is still a piece of very solid masonry, and must have been rather stiff working as a quarry. some painstaking burgher had, i found, made a desperate attempt on one of the huge chimney lintels of the great hall of the erection,--an apartment which sir walter greatly admired, and in which he lays the scene in the "pirate" between cleveland and jack bunce, but the lintel, a curious example of what, in the exercise of a little irish liberty, is sometimes termed a _rectilinear arch_, defied his utmost efforts; and, after half-picking out the keystone, he had to give it up in despair. the bishop's palace, of which a handsome old tower still remains tolerably entire, also served for a quarry in its day; and i was scarce sufficiently distressed to learn, that on almost the last occasion on which it had been wrought for this purpose, one of the two men engaged in the employment suffered a stone, which he had loosed out of the wall, to drop on the head of his companion, who stood watching for it below, and killed him on the spot. chapter xi. the bishop's palace at orkney--haco the norwegian--icelandic chronicle respecting his expedition to scotland--his death--removal of his remains to norway--why norwegian invasion ceased--straw-plaiting--the lassies of orkney--orkney type of countenance--celtic and scandinavian--an accomplished antiquary--old manuscripts--an old tune-book--manuscript letter of mary queen of scots--letters of general monck--the fearless covenanter--cave of the rebels--why the tragedy of "gustavus vasa" was prohibited--quarry of pickoquoy--its fossil shells--journey to stromness--scenery--birth-place of malcolm, the poet--his history--one of his poems--his brother a free church minister--new scenery. the "upper story" of the bishop's palace, in which grim old haco died,--thanks to the economic burghers who converted the stately ruin into a quarry,--has wholly disappeared. though the death of this last of the norwegian invaders does not date more than ten years previous to the birth of the bruce, it seems to belong, notwithstanding, to a different and greatly more ancient period of scottish history; as if it came under the influence of a sort of aërial perspective, similar to that which makes a neighboring hill in a fog appear as remote as a distant mountain when the atmosphere is clearer. our national wars with the english were rendered familiar to our country folk of the last age, and for centuries before by the old scotch "_makkaris,_" barbour and blind harry, and in our own times by the glowing narratives of sir walter scott,--magicians who, unlike those ancient sorcerers that used to darken the air with their incantations, possessed the rare power of dissipating the mists and vapors of the historic atmosphere, and rendering it transparent. but we had no such chroniclers of the time, though only half an age further removed into the past, "when norse and danish galleys plied their oars within the frith of clyde, and floated haco's banner trim above norweyan warriors grim, savage of heart and large of limb." and hence the thick haze in which it is enveloped. curiously enough, however, this period, during which the wild scot had to contend with the still wilder wanderers of scandinavia in fierce combats that he was too little skilful to record, and which appears so obscure and remote to his descendants, presents a phase comparatively near, and an outline proportionally sharp and well-defined to the intelligent peasantry of iceland. _their_ barbours and blind harries came a few ages sooner than ours, and the fog, in consequence, rose earlier; and so, while scotch antiquaries of no mean standing can say almost nothing about the expedition or death-bed of haco, even the humbler icelanders, taught from their sagas in the long winter nights, can tell how, harassed by anxiety and fatigue, the monarch sickened, and recovered, and sickened again; and how, dying in the bishop's palace, his body was interred for a winter in the cathedral, and then borne in spring to the burying-place of his ancestors in norway. the only clear vista on the death of haco which now exists is that presented by an icelandic chronicler: to which, as it seems so little known even in orkney that the burying-place of the monarch is still occasionally sought for in the cathedral, i must introduce the reader. i quote from an extract containing the account of haco's expedition against scotland, which was translated from the original icelandic by the rev. james johnstone, chaplain to his britannic majesty's envoy extraordinary at the court of denmark, and appeared in the "edinburgh magazine" for . "king haco," says the chronicler, "now in the seven and fortieth year of his reign, had spent the summer in watchfulness and anxiety. being often called to deliberate with his captains, he had enjoyed little rest; and when he arrived at kirkwall, he was confined to his bed by his disorder. having lain for some nights, the illness abated, and he was on foot for three days. on the first day he walked about in his apartments; on the second he attended at the bishop's chapel to hear mass; and on the third he went to magnus church, and walked round the shrine of st. magnus, earl of orkney. he then ordered a bath to be prepared, and got himself shaved. some nights after, he relapsed, and took again to his bed. during his sickness he ordered the bible and latin authors to be read to him. but finding his spirits were too much fatigued by reflecting on what he had heard, he desired norwegian books might be read to him night and day: first the lives of saints; and, when they were ended, he made his attendants read the chronicles of our kings, from holden the black, and so of all the norwegian monarchs in succession, one after the other. the king still found his disorder increasing. he therefore took into consideration the pay to be given to his troops, and commanded that a merk of fine silver should be given to each courtier, and half a merk to each of the masters of the lights, chamberlain, and other attendants on his person. he ordered all the silver-plate belonging to his table to be weighed, and to be distributed if his standard silver fell short.... king haco received extreme unction on the night before the festival of st. lucia. thorgisl, bishop of stravanger, gilbert, bishop of hainar, henry, bishop of orkney, albert thorleif and many other learned men, were present; and, before the unction, all present bade the king farewell with a kiss.... the festival of the virgin st. lucia happened on a thursday; and on the saturday after, the king's disorder increased to such a degree, that he lost the use of his speech; and at midnight almighty god called king haco out of this mortal life. this was matter of great grief to all those who attended, and to most of those who heard of the event. the following barons were present at the death of the king:--briniolf johnson, erling alfson, john drottning, ronald urka, and some domestics who had been near the king's person during his illness. immediately on the decease of the king, bishops and learned men were sent for to sing mass.... on sunday the royal corpse was carried to the upper hall, and laid on a bier. the body was clothed in a rich garb, with a garland on its head, and dressed out as became a crowned monarch. the masters of the lights stood with tapers in their hands, and the whole hall was illuminated. all the people came to see the body, which appeared beautiful and animated; and the king's countenance was as fair and ruddy as while he was alive. it was some alleviation of the deep sorrow of the beholders to see the corpse of their departed sovereign so decorated. high mass was then sung for the deceased. the nobility kept watch by the body during the night. on monday the remains of king haco were carried to st. magnus church, where they lay in state that night. on tuesday the royal corpse was put in a coffin, and buried in the choir of st. magnus church, near the steps leading to the shrine of st. magnus, earl of orkney. the tomb was then closed, and a canopy was spread over it. it was also determined that watch should be kept over the king's grave all winter. at christmas the bishop and andrew plytt furnished entertainments, as the king had directed; and good presents were given to all the soldiers. king haco had given orders that his remains should be carried east to norway, and buried near his fathers and relatives. towards the end of winter, therefore, that great vessel which he had in the west was launched, and soon got ready. on ash wednesday the corpse of king haco was taken out of the ground: this happened the third of the nones of march. the courtiers followed the corpse to skalpeid, where the ship lay, and which was chiefly under the direction of the bishop thorgisl and andrew plytt. they put to sea on the first saturday in lent; but, meeting with hard weather, they steered for silavog. from this place they wrote letters to prince magnus, acquainting him with the news, and then sailed for bergen. they arrived at laxavog before the festival of st. benedict. on that day prince magnus rowed out to meet the corpse. the ship was brought near to the king's palace, and the body was carried up to a summer-house. next morning the corpse was removed to christ's church, and was attended by prince magnus, the two queens, the courtiers, and the town's people. the body was then interred in the choir of christ's church; and prince magnus addressed a long and gracious speech to those who attended the funeral procession. all the multitude present were much affected, and expressed great sorrow of mind." so far the icelandic chronicle. each age has as certainly its own mode of telling its stories as of adjusting its dress or setting its cap; and the mode of this northern historian is somewhat prolix. i am not sure, however, whether i would not prefer the simple minuteness with which he dwells on every little circumstance, to that dissertative style of history characteristic of a more reflective age, that for series of facts substitutes bundles of theories. cowper well describes the historians of this latter school, and shows how, on selecting some little-known personage of a remote time as their hero, "they disentangle from the puzzled skein in which obscurity has wrapped them up, the threads of politic and shrewd design that ran through all his purposes, and charge his mind with meanings that he never had, or, having, kept concealed." i have seen it elaborately argued by a writer of this class, that those wasting incursions of the northmen which must have been such terrible plagues to the southern and western countries of europe, ceased in consequence of their conversion to christianity; for that, under the humanizing influence of religion, they staid at home, and cultivated the arts of peace. but the hypothesis is, i fear, not very tenable. christianity, in even a purer form than that in which it first found its way among the ancient scandinavians, and when at least as generally recognized nationally as it ever was by the subjects of haco, has failed to put down the trade of aggressive war. it did not prevent honest, obstinate george the third from warring with the americans or the french: it only led him to enjoin a day of thanksgiving when his troops had slaughtered a great many of the enemy, and to ordain a fast when the enemy had slaughtered, in turn, a great many of his troops. and haco, who, though he preferred the lives of the saints, and even of his ancestors, who could not have been very great saints, to the scriptures, seems, for a king, to have been a not undevout man in his way, and yet appears to have had as few compunctions visitings on the score of his scottish war as george the third on that of the french or the american one. christianity, too, ere his invasion of scotland, had been for a considerable time established in his dominions, and ought, were the theory a true one, to have operated sooner. the cathedral of st. magnus, when he walked round the shrine of its patron saint, was at least a century old. the true secret of the cessation of norwegian invasion seems to have been the consolidation, under vigorous princes, of the countries which had lain open to it,--a circumstance which, in the later attempts of the invaders, led to results similar to those which broke the heart of tough old haco, in the bishop's palace at kirkwall. from the ruins i passed to the town, and spent a not uninstructive half-hour in sauntering along the streets in the quiet of the evening, acquainting myself with the general aspect of the people. i marked, as one of the peculiar features of the place, groups of tidily-dressed young women, engaged at the close-heads with their straw plait,--the prevailing manufacture of the town,--and enjoying at the same time the fresh air and an easy chat. the special contribution made by the lassies of orkney to the dress of their female neighbors all over the empire, has led to much tasteful dressing among themselves. orkney, on its gala, days, is a land of ladies. what seems to be the typical countenance of these islands unites an aquiline but not prominent nose to an oval face. in the ordinary scotch and english countenance, when the nose is aquiline it is also prominent, and the face is thin and angular, as if the additional height of the central feature had been given it at the expense of the cheeks, and of lateral shavings from off the chin. the hard duke-of-wellington face is illustrative of this type. but in the aquiline type of orkney the countenance is softer and fuller, and, in at least the female face, the general contour greatly more handsome. dr. kombst, in his ethnographic map of britain and ireland, gives to the coast of caithness and the shetland islands a purely scandinavian people, but to the orkneys a mixed race, which he designates the scandinavian-gaelic. i would be inclined, however,--preferring rather to found on those traits of person and character that are still patent, than on the unauthenticated statements of uncertain history,--to regard the people as essentially one from the northern extremity of shetland to the ord hill of caithness. beyond the ord hill, and on to the northern shores of the frith of cromarty, we find, though unnoted on the map, a different race,--a race strongly marked by the celtic lineaments, and speaking the gaelic tongue. on the southern side of the frith, and extending on to the bay of munlochy, the purely scandinavian race again occurs. the sailors of the danish fleet which four years ago accompanied the crown prince in his expedition to the faroe islands were astonished when, on landing at cromarty, they recognized in the people the familiar cast of countenance and feature that marked their country folk and relatives at home; and found that they were simply scandinavians like themselves, who, having forgotten their danish, spoke scotch instead. rather more than a mile to the west of the fishing village of avoch there commences a celtic district, which stretches on from munlochy to the river nairne; beyond which the scandinavian and teutonic-scandinavian border that fringes the eastern coast of scotland extends unbroken southwards through moray, banff, and aberdeen, on to forfar, fife, the lothians, and the mearns. these two intercalated patches of celtic people in the northern tract,--that extending from the ord hill to the cromarty frith, and that extending from the bay of munlochy to the nairne,--still retaining, as they do, after the lapse of ages, a sharp distinctness of boundary in respect of language, character, and personal appearance, are surely great curiosities. the writer of these chapters was born on the extreme edge of one of these patches, scarce a mile distant from a gaelic-speaking population; and yet, though his humble ancestors were located on the spot for centuries, he can find trace among them of but one celtic name; and their language was exclusively the lowland scotch. for many ages the two races, like oil and water, refused to mix. i spent the evening very agreeably with one of the free church elders of the place, mr. george petrie, an accomplished antiquary; and found that his love of the antique, joined to an official connection with the county, had cast into his keeping a number of curious old papers of the sixteenth, seventeenth, and eighteenth centuries,--not in the least connected, some of them, with the legal and civic records of the place, but which had somehow stuck around these, in their course of transmission from one age to another, as a float of brushwood in a river occasionally brings down along with it, entangled in its folds, uprooted plants and aquatic weeds, that would otherwise have disappeared in the cataracts and eddies of the upper reaches of the stream. dead as they seemed, spotted with mildew, and fretted by the moth, i found them curiously charged with what had once been intellect and emotion, hopes and fears, stern business and light amusement. i saw, among the other manuscripts, a thin slip of a book, filled with jottings, in the antique square-headed style of notation, of old scotch tunes, apparently the work of some musical county-clerk of orkney in the seventeenth century; but the paper, in a miserable state of decay, was blotted crimson and yellow with the rotting damps, and the ink so faded, that the notation of scarce any single piece in the collection seemed legible throughout. less valuable and more modern, though curious from their eccentricity, there lay, in company with the music, several pieces of verse, addressed by some orcadian claud halcro of the last age, to some local patron, in a vein of compliment rich and stiff as a piece of ancient brocade. a peremptory letter, bearing the autograph signature of mary queen of scots, to torquil mcleod of dunvegan, who had been on the eve, it would seem, of marrying a daughter of donald of the isles, gave the skye chieftain, "to wit" that, as he was of the blood royal of scotland, he could form no matrimonial alliance without the royal permission,--a permission which, in the case in point, was not to be granted. it served to show that the woman who so ill liked to be thwarted in her own amours could, in her character as the queen, deal despotically enough with the love affairs of other people. side by side with the letter of mary there were several not less peremptory documents of the times of the commonwealth, addressed to the sheriff of orkney and shetland, in the name of his highness the lord protector, and that bore the signature of george monck. i found them to consist chiefly of dunning letters,--such letters as those duns write who have victorious armies at their back,--for large sums of money, the assessments laid on the orkneys by cromwell. another series of letters, some ten or twelve years later in their date, form portions of the history of a worthy covenanting minister, the rev. alexander smith of colvine, banished to north ronaldshay from the extreme south of scotland, for the offence of preaching the gospel, and holding meetings for social worship in his own house; and, as if to demonstrate his incorrigibility, one of the series,--a letter under his own hand, addressed from his island prison to the sheriff-depute in kirkwall,--showed him as determined and persevering in the offence as ever. it was written immediately after his arrival. "the poor inhabitants," says the writer, "so many as i have yet seen, have received me with much joy. _i intend, if the lord will, to preach christ to them next lord's day_, without the least mixture of anything that may smell of sedition or rebellion. if i be farther troubled for yt, i resolve to suffer with meekness and patience." the galloway minister must have been an honest man. deeming preaching his true vocation,--a vocation from the exercise of which he dared not cease, lest he should render himself obnoxious to the woe referred to by the apostle,--he yet could not steal a march on even the sheriff, whose professional duty it was to prevent him from doing _his_; and so he fairly warned him that he proposed breaking the law. the next set of papers in the collection dated after the revolution, and were full charged with an enthusiastic jacobitisin, which seems to have been a prevalent sentiment in orkney from the death of queen anne, until the disastrous defeat at culloden quenched in blood the hopes of the party. there is a deep cave still shown on the shores of westray, within sight of the forlorn patmos of the poor covenanter, in which, when the sun got on the whig side of the hedge, twelve gentlemen, who had been engaged in the rebellion of , concealed themselves for a whole winter. so perseveringly were they sought after, that during the whole time they dared not once light a fire, nor attempt fishing from the rocks to supply themselves with food; and, though they escaped the search, they never, it is said, completely recovered the horrors of their term of dreary seclusion, but bore about with them, in broken constitutions, the effects of the hardships to which they had been subjected. they must have had full time and opportunity, during that miserable winter, for testing the justice of the policy that had sent poor smith into exile, from his snug southern parish in the presbytery of dumfries, to the remotest island of the orkneys. the great lesson taught in providence during the seventeenth and part of the eighteenth century to our scottish country folk seems to have been the lesson of toleration; and as they were slow, stubborn scholars, the lash was very frequently and very severely applied. one of the jacobite papers of mr. petrie's collection,--a triumphal poem on the victory of gladsmuir,--which, if less poetical than the ode of hamilton of bangour on the same subject, is in no degree less curious,--serves to throw very decided light on a passage in literary history which puzzled dr. johnson, and which scarce any one would think of going to orkney to settle. johnson states, in his life of the poet thomson, that the "first operation" of the act passed in "for licensing plays" was the "prohibition of 'gustavus vasa,' a tragedy of mr. brook." "why such a work should be obstructed," he adds, "it is hard to discover." we learn elsewhere,--from the compiler of the "modern universal history," if i remember aright,--that "so popular did the prohibitory order of the lord chamberlain render the play," that, "on its publication the same year, not less than a thousand pounds were the clear produce." it was not, however, until more than sixty years after, when both johnson and brook were in their graves, that it was deemed safe to license it for the stage. now, the fact that a drama, in itself as little dangerous as "cato" or "douglas," should have been prohibited by the government of the day, in the first instance, and should have brought the author, on its publication, so large a sum in the second, can be accounted for only by a reference to the keen partisanship of the period, and the peculiar circumstances of parties. the jacobites, taught by the rebellion of at once the value of the highlands and the incompetency of the chevalier st. george as a leader, had begun to fix their hopes on the chevalier's son, charles edward, at that time a young but promising lad; and, with the tragedy of brook before them, neither they, nor the english government of the day could have failed to see the foreigner george the second typified--unintentionally, surely, on the part of brook, who was a "prince of wales" whig--in the foreigner christiern the second, the scotch highlanders in the mountaineers of dalecarlia, and the young prince in gustavus. in the jacobite manuscript of mr. petrie's collection, the parallelism is broadly traced; nor is it in the least probable, as the poem is a piece of sad mediocrity throughout, that it is a parallelism which was originated by its writer. it must have been that of his party; and led, i doubt not, five years before, to the prohibition of brook's tragedy, and to the singular success which attended its publication. the passage in the manuscript suggestive of this view takes the form of an address to the victorious prince, and runs as follows:-- "meanwhile, unguarded youth, thou stoodst alone; the cruel tyrant urged his armie on; but truth and goodness were the best of arms; and, fearless prince, thou smil'd at threatened harms. thus, glorious vasa worked in swedish mines,-- thus, helpless, saw his enemy's designs,-- till, roused, his hardy highlanders arose, and poured destruction on their foreign foes." i rose betimes next morning, and crossed the peerie [little] sea, a shallow prolongation of the bay of kirkwall, cut off from the main sea by an artificial mound, to the quarry of pickoquoy, somewhat notable, only a few years ago, as the sole locality in which shells had been detected in the old red sandstone of scotland. but these have since been found in the neighborhood of thurso, by mr. robert dick, associated with bones and plates of the asterolepis, and by mr. william watt on the opposite side of the mainland of orkney, at marwick head. so far as has yet been ascertained, they are all of one species, and more nearly resemble a small cyclas than any other shell. they are, however, more deeply sulcated in concentric lines, drawn, as if by a pair of compasses, from the umbone, and somewhat resembling those of the genus astarte, than any species of cyclas with which i am acquainted. in all the specimens i have yet seen, it appears to be rather a thick dark epidermis that survives, than the shell which it covered; nay, it seems not impossible that to its thick epidermis, originally an essentially different substance from that which composed the calcareous case, the shell may have owed its preservation as a fossil; while other shells, its contemporaries, from the circumstance of their having been unfurnished with any such covering, may have failed to leave any trace of their existence behind them. it seems at least difficult to conceive of a sea inhabited by many genera of fishes, each divided into several species, and yet furnished with but one species of shell. i found the quarry of pickoquoy,--a deep excavation only a few yards beyond the high-water mark, and some two or three yards under the high-water level,--deserted by the quarrymen, and filled to the brim by the overflowing of a small stream. i succeeded, however, in detecting its shells _in situ_. they seem restricted chiefly to a single stratum, scarcely half an inch in thickness, and lie, not thinly scattered over the platform which they occupy, but impinging on each other, like all the gregarious shells, in thickly-set groups and clusters. there occur among them occasional scales of dipteri; and on some of the fragments of rock long exposed around the quarry-mouth to the weather i found them assuming a pale nacreous gloss,--an effect, it is not improbable, of their still retaining, attached to the epidermis, a thin film of the original shell. the world's history must be vastly more voluminous now, and greatly more varied in its contents, than when the stratum which they occupy formed the upper layer of a muddy sea-bottom, and they opened their valves by myriads, to prey on the organic atoms which formed their food, or shut them again, startled by the shadow of the dipterus, as he descended from the upper depths of the water to prey upon them in turn. the palate of this ancient ganoid is furnished with a curious dental apparatus, formed apparenly, like that of the recent wolf-fish, for the purpose of crushing shells. about mid-day i set out by the mail-gig for stromness. for the first few miles the road winds through a bare solitary valley, overlooked by ungainly heath-covered hills of no great altitude, though quite tall enough to prevent the traveller from seeing anything but themselves. as he passes on, the valley opens in front on an arm of the sea, over which the range of hills on the right abruptly terminates, while that on the left deflects into a line nearly parallel to the shore, leaving a comparatively level strip of moory land, rather more than a mile in breadth, between the steeper acclivities and the beach. a tall naked house rises between the road and the sea. two low islands immediately behind it, only a few acres in extent,--one of them bearing a small ruin on its apex,--give a little variety to the central point in the prospect which the naked house forms; but the arm of the sea, bordered, at the time i passed, by a broad brown selvage of sea-weed, is as tame and flat as a dutch lake; the background beyond, a long monotonous ridge, is bare and treeless; and in front lies the brown moory plain, bordered by the dull line of hills and darkened by scattered stacks of peat. the scene is not at all such a one as a poet would, for its own sake, delight to fancy; and yet, in the recollection of at least one very pleasing poet, its hills, and islands, and blue arm of the sea, its brown moory plain, and tall naked house rising in the midst, must have been surrounded by a sunlit atmosphere of love and desire, bright enough to impart to even its tamest features a glow of exquisiteness and beauty. malcolm the poet was born, and spent his years of boyhood and early youth, in the tall naked house; and the surrounding landscape is that to which he refers in his "tales of flood and field," as rising in imagination before him, bright in the red gleam of the setting sun, when, on the steep slopes of the pyrenees, the "silent stars of night were twinkling high over his head," and the "tents of the soldiery glimmering pale through the gloom." the tall house is the manse of the parish of frith and stennis; and the poet was the son of the rev. john malcolm, its minister. here, when yet a mere lad, dreaming, in the quiet obscurity of an orkney parish, far removed from the seat of war and the literary circles, of poetic celebrity and military renown, he addressed a letter to the duke of kent, the father of our sovereign lady the reigning monarch, expressing an ardent wish to obtain a commission in the army then engaged in the peninsula. the letter was such as to excite the interest of his royal highness, who replied to it by return of post, requesting the writer to proceed forthwith to london; for which he immediately set out, and was received by the duke with courtesy and kindness. he was instructed by him to take ship for spain, in which he arrived as volunteer; and, joining the army, engaged at the time in the siege of st. sebastian, under general graham, he was promoted shortly after, through the influence of his generous patron, to a lieutenancy in the d highlanders. he served in that distinguished regiment on to the closing campaign of the pyrenees; but received at the battle of toulouse a wound so severe as to render him ever after incapable of active bodily exertion; and so he had to retire from the army on half-pay, and a pension honorably earned. the history of his career as a soldier he has told with singular interest, in one of the earlier volumes of "constable's miscellany;" and his poems abound in snatches of description painfully true, drawn from his experience of the military life,--of scenes of stern misery and grim desolation, of injuries received, and of sufferings inflicted,--that must have contrasted sadly in his mind, in their character as gross realities, with the dreamy visions of conquest and glory in which he had indulged at an earlier time. the ruin of st. sebastian, complete enough, and attended with circumstances of the horrible extreme enough, to appal men long acquainted with the trade of war, must have powerfully impressed an imaginative susceptible lad, fresh from the domesticities of a rural manse, in whose quiet neighborhood the voice of battle had not been heard for centuries, and surrounded by a simple people, remarkable for the respect which they bear to human life. in all probability, the power evinced in his description of the siege, and of the utter desolation in which it terminated, is in part owing to the fresh impressibility of his mind at the time. such, at least, was my feeling regarding it, as i caught myself muttering some of its more graphic passages, and saw, from the degree of alarm evinced by the boy who drove the mail-gig, that the sounds were not quite lost in the rattle of that somewhat rickety vehicle, and that he had come to entertain serious doubts respecting the sanity of his passenger:-- "sebastian, when i saw thee last, it was in desolation's day, as through thy voiceless streets i passed, thy piles in heaps of rubbish lay; the roofless fragments of each wall bore many a dent of shell and ball; with blood were all thy gateways red, and thou,--a city of the dead! with fire and sword thy walks were swept: exploded mines thy streets had heaped in hills of rubbish; they had been traversed by gabion and fascine, with cannon lowering in the rear in dark array,--a deadly tier,-- whose thunder-clouds, with fiery breath, sent far around their iron death; the bursting shell, in fragments flung athwart the skies, at midnight sung, or, on its airy pathway sent, its meteors sweep the firmament. thy castle, towering o'er the shore, keeled on its rock amidst the roar of thousand thunders, for it stood in circle of a fiery flood; and crumbling masses fiercely sent from its high frowning battlement, smote by the shot and whistling shell, with groan and crash in ruin fell. through desert streets the mourner passed, midst-walls that spectral shadows east, like some fair spirit wailing o'er the failed scenes it loved of yore; no human voice was heard to bless that place of waste and loneliness. i saw at eve the night-bird fly, and vulture dimly flitting by, to revel o'er each morsel stolen from the cold corse, all black and swoln that on the shattered ramparts lay, of him who perished yesterday,-- of him whose pestilential steam rose reeking on the morning beam,-- whose fearful fragments, nearly gone, were blackening from the bleaching bone. the house-dog bounded o'er each scene where cisterns had so lately been: away in frantic haste he sprung, and sought to cool his burning tongue. he howled, and to his famished cry the dreary echoes gave reply; and owlet's dirge, through shadows dim, rolled back in sad response to him." the father was succeeded in his parish by the brother of malcolm,--a gentleman to whom, during my stay in orkney, i took the liberty of introducing myself in his snug little free church manse at the head of the bay, and in whose possession i found the only portrait of the poet which exists. it is that of a handsome and interesting looking _young_ man, though taken not many years before his death; for, like the greater number of his class, he did not live to be an old one, dying under forty. his brother the clergyman kindly accompanied me to two quarries in the neighborhood of his new domicil, which i found, like almost all the dry-stone fences of the district, speckled with scales, occipital plates, and gill-covers, of osteolepides and dipteri, but containing no entire ichthyolites. he had taken his side in the church controversy, he told me, firmly, but quietly; and when the disruption came, and he found it necessary to quit the old manse, which had been a home to his family for well nigh two generations, and in which both he and his brother had been born, he scarce knew what his people were to do, nor in what proportion he was to have followers among them. somewhat to his surprise, however, they came out with him almost to a man; so that his successor in the parish church had sometimes, he understood, to preach to congregations scarcely exceeding half a dozen. i had learned elsewhere how thoroughly mr. malcolm was loved and respected by his parishioners; and that unconsciousness on his own part of the strength of their affection and esteem, which his statement evinced, formed, i thought, a very pleasing trait, and one that harmonized well with the finely-toned unobtrusiveness and unconscious elegance which characterized the genius of his deceased brother. a little beyond the free church manse the road ascends between stone walls, abounding in fragments of ichthyolites, weathered blue by exposure to the sun and wind; and the top of the eminence forms the water-shed in this part of the mainland, and introduces the traveller to a scene entirely new. the prospect is of considerable extent; and, what seems strange in orkney, nowhere presents the traveller,--though it contains its large inland lake,--with a glimpse of the sea. chapter xii. hills of orkney--their geologic composition--scene of scott's "pirate"--stromness--geology of the district--"seeking beasts"--conglomerate in contact with granite--a palæozoic hudson's bay--thickness of conglomerate of orkney--oldest vertebrate yet discovered in orkney--its size--figure of a characteristic plate of the asterolepis--peculiarity of old red fishes--length of the asterolepis--a rich ichthyolite bed--arrangement of the layers--queries as to the cause of it--minerals--an abandoned mine--a lost vessel--kelp for iodine--a dangerous coast--incidents of shipwreck--hospitality--stromness museum--diplopterus mistaken for dipterus--their resemblances and differences--visit to a remarkable stack--paring the soil for fuel, and consequent barrenness--description of the stack--wave-formed caves--height to which the surf rises. the orkneys, like the mainland of scotland, exhibit their higher hills and precipices on their western coasts: the ward hill of hoy attains to an elevation of sixteen hundred feet; and there are some of the precipices which skirt the island of which it forms so conspicuous a feature, that rise sheer over the breakers from eight hundred to a thousand. unlike, however, the arrangement on the mainland, it is the newer rocks that attain to the higher elevations; the heights of hoy are composed of that arenaceous upper member of the lower old red sandstone,--the last formed of the palæozoic deposits of orkney,--which overlies the ichthyolitic flagstones and shales of caithness at dunnet head, and the ichthyolitic nodular beds of inverness, ross, and cromarty, at culloden, tarbet ness, within the northern sutor, and along the bleak ridge of the maolbuie. it is simply a tall upper story of the formation, erected along the western line of coast in the orkneys, which the eastern line wholly wants. its screen of hills forms a noble background to the prospect which opens on the traveller as he ascends the eminence beyond the free church manse of frith and stennis. a large lake, bare and treeless, like all the other lakes and lochs of orkney, but picturesque of outline, and divided into an upper and lower sheet of water by two low, long promontories, that jut out from opposite sides, and so nearly meet as to be connected by a threadlike line of road, half mound, half bridge, occupies the middle distance. there are moory hills and a few cottages in front; and on the promontories, conspicuous in the landscape, from the relief furnished by the blue ground of the surrounding waters, stand the tall stones of stennis,--one group on the northern promontory, the other on the south. a gray old-fashioned house, of no very imposing appearance, rises between the road and the lake. it is the house of stennis, or turmister, in which scott places some of the concluding scenes of the "pirate," and from which he makes cleveland and his fantastic admirer jack bunce witness the final engagement, in the bay of stromness, between the halcyon sloop of war and the savage goffe. nor does it matter anything that neither sea nor vessels can be seen from the house of turmister: the fact which would be so fatal to a dishonest historian tells with no effect against the honest "_maker_," responsible for but the management of his tale. i got on to stromness; and finding, after making myself comfortable in my inn, that i had a fine bright evening still before me, longer by some three or four degrees of north latitude than the july evenings of edinburgh, i set out, hammer in hand, to explore. stromness is a long, narrow, irregular strip of a town, fairly thrust by a steep hill into the sea, on which it encroaches in a broken line of wharf-like bulwarks, along which, at high water, vessels of a hundred tons burden float so immediately beside the houses, that their pennants on gala days wave over the chimney tops. the steep hill forms part of a granitic axis, about six miles in length by a mile in breadth, which forms the backbone of the district, and against which the great conglomerate and lower schists of the old red are upturned at a rather high angle. it is wrapped round in some places by a thin caul of the stratified primary rocks. immediately over the town, on the brow of the eminence, where the granitic axis had been laid bare in digging a foundation for the free church manse, i saw numerous masses of schistose-gneiss, passing in some of the beds into a coarse-grained mica-schist, and a lustrous hornblendic slate, that had been quarried from over it, and which may be still seen built up into the garden-wall of the erection. i walked out towards the west, to examine the junction of the granite and the great conglomerate, where it is laid bare by the sea, little more than a quarter of a mile outside the town. there was a horde of noisy urchins a little beyond the inn, who, having seen me alight from the mail-gig, had determined in their own minds that i was engaged in the political canvass going forward at the time, but had not quite ascertained my side. they now divided into two parties; and when the one, as i passed, set up a "hurra for dundas," the other met them from the opposite side of the street, with a counter cry of "anderson forever." immediately after clearing the houses, i was accosted by a man from the country. "ye'll be seeking beasts," he said: "what price are cattle gi'en the noo?" "yes, seeking _beasts_," i replied, "but very old ones: i have come to hammer your rocks for petrified fish." "i see, i see," said the man; "i took ye by ye'er gray plaid for a drover; but i ken something about the stane fish too; there's lots o' them in the quarries at skaill." i found the great conglomerate in immediate contact with the granite, which is a ternary of the usual components, somewhat intermediate in color between that of peterhead and aberdeen, and which at this point bears none of the caul of stratified primary rock by which it is overlaid on the brow of the hill. when the great conglomerate, which is mainly composed of it here, was in the act of forming, this granite must have been one of the surface rocks of the locality, and in no respect a different stone from what it is now. the widely-spread conglomerate base of the old red sandstone, which presents, over an area of so many thousand square miles, such an identity of character, that specimens taken from the neighborhood of lerwick, in shetland, can scarce be distinguished from specimens detached from the hills which rise over the great caledonian valley, contains in various places, as under the northern sutor, for instance, and along the shores of navity, fragments of rock which have not been detected _in situ_ in the districts in which they occur as agglomerated pebbles. in general, however, we find it composed of the debris of those very granites and gneisses which, as in the case of the granitic axis here, were forced through it, and through the overlying deposits, by deep-seated convulsions, long posterior in date to its formation. it appears to have been formed in a vast oceanic basin of primary rock,--a palæozoic hudson's or baffin's bay,--partially surrounded, mayhap, by bare primary continents, swept by numerous streams, rapid and headlong, and charged with the broken debris of the inhospitable regions which they drained. the graptolite-bearing grauwacke of banffshire seems to have been the only fossiliferous rock that occurred throughout the extent of this ancient northern basin. the conglomerate of orkney, like that of moray and ross, varies from fifty to a hundred yards in thickness. it is not overlaid in this section by the thick bed of coarse-grained sandstone, so well-marked a member of the formation at cromarty, nigg, and gamrie, and along the northern shores of the beauly frith; but at once passes into those gray bituminous flagstones so immensely developed in caithness and the orkneys. i traced the formation upwards this evening, walking along the edges of the upheaved strata, from where the conglomerate leans against the granite, till where it merges into the gray flagstones, and then pursued these from older and lower to newer and higher layers, anxious to ascertain at what distance over the base the more ancient organisms of the system first appear, and what their character and kind. and little more than a hundred _yards_ over the granite, and somewhat less than a hundred _feet_ over the upper stratum of the great conglomerate, i found what i sought,--a well-marked bone, perhaps the oldest vertebrate remain yet discovered in orkney, embedded in a light grayish-colored layer of hard flag. what, asks the reader, was the character of the ancient denizen of the palæozoic basin of which it had formed a part? was it a large or small fish, or of a high or low order? not certainly of a low order, and by no means of a small size. the organism in the rock was a specimen of that curious nail-shaped bone of the asterolepis which occurs as a central ridge in the single plate that occupies in this genus the wide curve of the under jaw, and as it was fully five inches in length from head to point, the plate to which it belonged must have measured ten inches across, and the frontal occipital buckler with which it was associated, one foot two inches in length (not including the three accessory plates at the nape), by ten inches in breadth. and if built, as it probably was, in the same massy proportions as its brother coelacanths the holoptychius or glyptolepis, the individual to which the nail-shaped bone belonged must have been, judging from the size of the corresponding parts in these ichthyolites, at least twice as large an animal as the splendid clashbennie holoptychius of the upper old red, now in the british museum. the bulkiest icthyolites yet found in any of the divisions of the old red system are of the genus asterolepis; and to this genus, and to evidently an individual of no inconsiderable size, this oldest of the organisms of the orkney belonged. i was so interested in the fact, that before leaving this part of the country, i brought dr. garson, stromness, and mr. william watt, jun., skaill, both very intelligent palæontologists, to mark the place and character of the fossil, that they might be able to point it out to geological visitors in the future, or, if they preferred removing it to their town museum, to indicate to them the stratum in which it had lain. for the present, i merely request the reader to mark, in the passing, that the most ancient organic remain yet found in the old red of this part of the country, nay, judging from its place, one of the most ancient yet found in scotland,--so far as i know, absolutely the _most_ ancient,--belonged to a ganoid as bulky as a large porpoise, and which, as shown by its teeth and jaws, possessed that peculiar organization which characterized the reptile fish of the upper devonian and carboniferous periods. as there are, however, no calculations more doubtful or more to be suspected than those on which the size and bulk of the extinct animals are determined from some surviving fragment of their remains,--plate or bone,--i must attempt laying before the scientific reader at least a portion of the data on which i found. [illustration] this figure represents not inadequately one of the most characteristic plates of the asterolepis. a very considerable fragment of what seems to be the same plate has been figured by agassiz from a cast of one of the huge specimens of professor asmus ("old red," table , fig. ); but as no evidence regarding its true place had turned up at the time it was supposed by the naturalist to form part of the opercular covering of the animal. it belonged, however, to a different portion of the head. in almost all the fish that appear at our tables the space which occurs within the arched sweep of the lower jaws is mainly occupied by a complicated osseous mechanism, known to anatomists as the hyoid bone and branchiostegous rays; and which serves both to support the branchial arches and the branchiostegous membrane. now, in the fish of the old red sandstone, if we except some of the acanthodians, we find no trace of this piece of mechanism: the arched space is covered over with dermal plates of bone, as a window is filled up with panes. three plates, resembling very considerably the three divisions of a pointed gothic window, furnished with a single central mullion, divided atop into two branches, occupied the space in the genera osteolepis and diplopterus; and two plates resembling the divisions of a pointed gothic window, whose single central mullion does _not_ branch atop, filled it up in the genera holoptychius and glyptolepis. in the genus asterolepis this arch-shaped space was occupied, as i have said, by a single plate,--that represented in the wood-cut; and the nail-shaped bone rose on its internal surface along the centre,--the nail-head resting immediately beneath the centre of the arch, and the nail-point bordering on the isthmus below, at which the two shoulder-bones terminated. now, in all the specimens which i have yet examined, the form and proportions of this plate are such that it can be very nearly inscribed in a semi-circle, of which the length of the nail is the radius. a nail five inches in length must have belonged to a plate ten inches in its longer diameter. i have ascertained further, that this longer diameter was equal to the shorter diameter of the creature's frontal buckler, measured across about two thirds of its entire length from the nape; and that a transverse diameter of ten inches at this point was associated in the buckler with a longitudinal diameter of fourteen inches from the nape to the snout. thus five inches along the nail represent fourteen inches along the occipital shield. the proportion, however, which the latter bore to the entire body in this genus has still to be determined. the corresponding frontal shield in the coccosteus was equal to about one-fifth the creature's entire length, and in the osteolepis and diplopterus, to nearly one-seventh its length; while the length of the _glyptolepis leptopterus_, a fish of the same family as the asterolepis, was about five and a half times that of its occipital shield. if the asterolepis was formed in the proportions of the diplopterus, the ancient individual to which this nail-like bone belonged must have been about eight feet two inches in length; but if moulded, as it more probably was, in the proportions of the glyptolepis, only six feet five inches. all the coelacanths, however, were exceedingly massive in proportion to their length; they were fish built in the square, muscular, thick-set, dirk-hatterick and balfour-of-burley style; and of the russian specimens, some of the larger bones must have belonged to individuals of from twice to thrice the length of the stromness one. passing upwards along the strata, step by step, as along a fallen stair, each stratum presenting a nearly perpendicular front, but losing, in the downward slant of the _tread_, as a carpenter would say, the height attained in the _rise_, i came, about a quarter of a mile farther to the west, and several hundred feet higher in the formation, upon a fissile dark-colored bed, largely charged with ichthyolites. the fish i found ranged in three layers,--the lower layer consisting almost exclusively of dipterians, chiefly osteolepides; the middle layer, of acanthodians, of the genera cheiracanthus and diplacanthus; and the upper layer, of cephalaspides, mostly of one species, the _coccosteus decipiens_. i found exactly the same arrangement in a bed considerably higher in the system, which occurs a full mile farther on,--the dipterians at the bottom, the acanthodians in the middle, and the cephalaspides atop; and was informed by mr. william watt, a competent authority in the case, that the arrangement is comparatively a common one in the quarries of orkney. how account for the phenomenon? how account for the three storeys, and the apportionment of the floors, like those of a great city, each to its own specific class of society? why should the first floor be occupied by osteolepides, the second by cheiracanthi and their congeners, and the third by coccostei? was the arrangement an effect of normal differences in the constitutions of the several families, operated upon by some deleterious gas or mineral poison, which, though it eventually destroyed the whole, did not so simultaneously, but consecutively,--the families of weakest constitution first, and the strongest last? or were they exterminated by some disease, that seized upon the families, not at once, but in succession? or did they visit the locality serially, as the haddock now visits our coasts in spring, and the herring towards the close of summer; and were then killed off, whether by poison or disease, as they came? these are questions which may never be conclusively answered. it is well, however, to observe, as a curious geological fact, that peculiar arrangement of the fossils by which they are suggested, and to record the various instances in which it occurs. the minerals which i remarked among the schists here as most abundant are a kind of black ironstone, exceedingly tough and hard, occurring in detached masses, and a variety of bright pyrites disseminated among the darker flagstones, either as irregularly-formed, brassy-looking concretions of small size, or spread out on their surfaces in thin leaf-like films, that resemble, in some of the specimens, the icy-foliage with which a severe frost encrusts a window-pane. still further on i came upon a vein of galena; but a miner's excavation in the solid rock, a little above high-water mark, quite as dark and nearly as narrow as a fox-earth, showed me that it had been known long before, and, as the workings seemed to have been deserted for ages, known to but little purpose. the crystals of ore, small and thinly scattered, are embedded in a matrix of barytes, stromnite, and other kindred minerals, and the thickness of the entire vein is not very considerable. i have since learned, from the "statistical account of the parish of sandwick," that the workings of the mine penetrate into the rock for about a hundred yards, but that it has been long abandoned, "as a speculation which would not pay." i observed scattered over the beach, in the neighborhood of the lead mine, considerable quantities of the hard chalk of england; and, judging there could be no deposits of the hard chalk in this neighborhood, i addressed myself on my way back, to a kelp-burner engaged in wrapping up his fire for the night with a thick covering of weed, to ascertain how it had come there. "ah, master," he replied, "that chalk is all that remains of a fine large english vessel, that was knocked to pieces here a few years ago. she was ballasted with the chalk; and as it is a light sort of stone, the surf has washed it ashore from that low reef in the middle of the tideway where she struck and broke up. most of the sailors, poor fellows, lie in the old churchyard, beside the broken ruin yonder. it is a deadly shore this to seafaring-men." i had understood that the kelp-trade was wholly at an end in orkney; and, remarking that the sea-weed which he employed was chiefly of one kind,--the long brown fronds of tang dried in the sun,--i inquired of him to what purpose the substance was now employed, seeing that barilla and the carbonate of soda had supplanted it in the manufacture of soap and glass, and why he was so particular in selecting his weed. "it's some valuable medicine," he said, "that's made of the kelp now: i forget its name; but it's used for bad sores and cancer; and we must be particular in our weed, for it's not every kind of weed that has the medicine in't. there's most of it, we're told, in the leaves of the tang." "is the name of the drug," i asked, "iodine?" "ay, that must be just it," he replied,--"iodine; but it doesn't make such a demand for kelp as the glass and the soap." i afterwards learned that the kelp-burner's character of this strip of coast, as peculiarly fatal to the mariner, was borne out by many a sad casualty, too largely charged with the wild and the horrible to be lightly forgotten. the respected free church clergyman of stromness, mr. learmonth, informed me that, ere the disruption, while yet minister of the parish, there were on one sad occasion eight dead bodies carried of a sabbath morning to his manse door. some of the incidents connected with these terrible shipwrecks, as related with much graphic effect by a boatman who carried me across the sound, on an exploratory ramble to the island of hoy, struck me as of a character considerably beyond the reach of the mere dealer in fiction. the master of one hapless vessel, a young man, had brought his wife and only child with him on the voyage destined to terminate so mournfully; and when the vessel first struck, he had rushed down to the cabin to bring them both on deck, as their only chance of safety. he had, however, unthinkingly shut the cabin-door after him; a second tremendous blow, as not unfrequently happens in such cases, so affected the framework of the sides and deck, that the door was jammed fast in its frame. and long ere it could be cut open,--for no human hand could unfasten it,--the vessel had filled to the beams, and neither the master nor his wife and child were ever seen more. in another ship, wrecked within a cable-length of the beach, the mate, a man of herculean proportions, and a skilful swimmer, stripped and leaped overboard, not doubting his ability to reach the shore. but he had failed to remark what in such circumstances is too often forgotten, that the element on which he flung himself, beaten into foam against the shallows, was, according to mr. bremner's shrewd definition, not water, but a mixture of water and air, specifically lighter than the human body; and so at the shore, though so close at hand, he never arrived, disappearing almost at the vessel's side. "the ground was rough," said my informant, "and the sea ran mountains high; and i can scarce tell you how i shuddered on finding, long ere his corpse was thrown up, his two eyes detached from their sockets, staring from a wreath of sea-weed." there is in this last circumstance, horrible enough surely for the wildest german tale ever written, a unique singularity, which removes it beyond the reach of invention. at my inn i found a pressing invitation awaiting me from the free church manse, which i was urged to make my home so long as i remained in that part of the country. a geologist, however, fairly possessed by the enthusiasm without which weak man can accomplish nothing,--whether he be a deer-stalker or mammoth-fancier, or angle for live salmon or dead pterichthyes,--has a trick of forgetting the right times of dining and taking tea, and of throwing the burden of his bodily requirements on early extempore breakfasts and late suppers; and so reporting myself a man of irregular habits and bad hours, whose movements could not in the least be depended upon, i had to decline the hospitality which would fain have adopted me as its guest, notwithstanding the badness of the character that, in common honesty, i had to certify as my own. next morning i breakfasted at the manse, and was introduced by mr. learmonth to two gentlemen of the place, who had been kindly invited to meet with me, and who, from their acquaintance with the geology of the district enabled me to make the best use of my time, by cutting direct on those cliffs and quarries in the neighborhood in which organic remains had been detected, instead of wearily re-discovering them for myself. there is a small but interesting museum in stromness, rich in the fossils of the locality; and i began the geologic business of the day by devoting an hour to the examination of its organisms, chiefly ichthyolites. i saw among them several good specimens of the genus pterichthys, and of what is elsewhere one of the rarer genera of the dipterians,--the diplopterus. a well-marked individual of the latter genus had, i found, been misnamed dipterus by some geological visitor who had recently come the way,--a mistake which, as in both ichthyolites the fins are similarly placed, occasionally occurs, but which may be easily avoided, when the specimens are in a tolerable state of preservation, by taking note of a few well-marked characteristics by which the genera are distinguished. in both dipterus and diplopterus the bright enamel of the scales was thickly punctulated by microscopic points,--the exterior terminations of funnel-shaped openings, that communicated between the surface and the cells of the middle table of the scale; but the form of the scales themselves was different,--that of the dipterus being nearly circular, and that of the diplopterus, save on the dorsal ridge, rhomboidal. again, the lateral line of the diplopterus was a raised line, running as a ridge along the scales; whereas that of the dipterus was a depressed one, existing as a furrow. their heads, too, were covered by an entirely dissimilar arrangement of plates. the rounded snout-plate of the diplopterus was suddenly contracted to nearly one-half its breadth by two semi-circular inflections, which formed the orbits of the eyes; full in the centre, a little above these, a minute, lozenge-shaped plate seemed as if inlaid in the larger one, the analogue, apparently, of the anterior frontal; and over all there expanded a broad plate, the superior frontal, half divided vertically by a line drawn downwards from the nape, which, however, stopped short in the middle; and fretted transversely by two small but deeply-indented rectangular marks, which, crossing from the central to two lateral plates, assumed the semblance of connecting pins. the snout of the dipterus was less round; it bore no mark of the eye-orbits; and the frontal buckler, broader in proportion to its length than that of the diplopterus, consisted of many more plates. i may here mention that the frontal buckler of diplopterus has not yet been figured nor described; whereas that of dipterus, though unknown as such, has been given to the world as the occipital covering of a supposed cephalaspian,--the polyphractus. polyphractus is, however, in reality a synonym for dipterus,--the one name being derived from a peculiarity of the animal's fins: the other, from the great number of its occipital plates. there is no science founded on mere observation that can be altogether free, in its earlier stages, from mistakes of this character,--mistakes to which the palæontologist, however skilful, is peculiarly liable. the teeth of the two genera were essentially different. those of the dipterus, exclusively palatal, were blunt and squat, and ranged in two rectangular patches;[ ] while those of the diplopterus bristled along its jaws and were slender and sharp. their tails, too, though both heterocercal, were diverse in their type. in each, an angular strip of gradually-diminishing scales,--a prolongation of the scaly coat which protected the body, and which covered here a prolongation of the vertebral column,--ran on to the extreme termination of the upper lobe; but there was in the diplopterus a greatly larger development of fin on the superior or dorsal side of the scaly strip than on that of the dipterus. if the caudal fin of the osteolepis be divided longitudinally into six equal parts, it will be found that one of these occurs on the upper side of the vertebral prolongation, and five on the under; in the caudal fin of the diplopterus so divided, rather more than _two_ parts will be found to occur on the upper side, and rather less than four on the under; while in the caudal fin of the dipterus the development seems to have been restricted to the under side exclusively; at least, in none of the many individuals which i have examined have i found any trace of caudal rays on the upper side. these are minute and somewhat trivial particulars; but the geologist may find them of use; and the non-geologist may be disposed to extend to them some little degree of tolerance, when he considers that they distinguished two largely developed genera of animals, to which the author of all did not deem it unworthy his wisdom to impart, in the act of creation, certain marked points of resemblance, and other certain points of dissimilarity. from the museum, accompanied by one of the gentlemen to whom mr. learmonth had introduced me at breakfast, and who obligingly undertook to act as my guide on the occasion, i set out to visit a remarkable stack on the sea-coast, about four miles north and west of stromness. we scaled together the steep granitic hill immediately over the town, and then cut on the stack, straight as the bird flies, across a trackless common, bare and stony, and miserably pared by the _flaughter_ spade. the landed proprietors in this part of the mainland are very numerous, and their properties small; and there are vast breadths of undivided common that encircle their little estates, as the atlantic encircles the orkneys. but the state in which i found the unappropriated parts of the district had in no degree the effect of making me an opponent of appropriation or the landholders. our country, had it been left as a whole to all its people, as the communist desiderates, would ere now be of exceedingly little value to any portion of them. the soil of the orkney commons has been so repeatedly pared off and carried away for fuel, that there are now wide tracts on which there is no more soil to pare, and which present, for the original covering of peaty mould, a continuous surface of pale boulder-clay, here and there mottled by detached tufts of scraggy heath, and here and there roughened by projections of the underlying rock. all is unredeemable barrenness. on the other hand, wherever a bit of private property appears, though in the immediate neighborhood of these ruined wastes, the surface is swarded over, and the soil is the better, not the worse, for the services which it has rendered to man in the past. whatever the chartist and the leveller may think of the matter, it is, i find, virtually on behalf of the many that the soil has been appropriated by the few. after passing from off the tract of moor which overlies the granitic axis of the district, to a tract equally moory which spreads over the gray flagstones, i marked, more especially in the hollows and ravines, where minute springs ooze from the rock, vast quantities of bog-iron embedded in the soil, and presenting greatly the appearance of the scoria of a smith's forge. the apparent scoria here is simply a reproduction of the iron of the underlying flagstones, transferred, through the agency of water, to that stratum of vegetable mould and boulder-clay which represents the recent period. i found the stack which i had been brought to see forming the picturesque centre of a bold tract of rock scenery. it stands out from the land as a tall insulated tower, about two hundred feet in height, sorely worn at its base by the breakers that ceaselessly fret against its sides, but considerably broader atop, where it bears a flat cover of sward on the same level with the tops of the precipices which in the lapse of ages have receded from around it. like the sward-crested hammock left by a party of laborers, to mark the depth to which they have cut in removing a bank or digging a pond, it remains to indicate how the attrition of the surf has told upon the iron-bound coast; demonstrating that lines of precipices hard as iron, and of giddy elevation, are in full retreat before the dogged perseverance of an assailant that, though baffled in each single attack, ever returns to the charge, and gains by an aggregation of infinitesimals,--the result of the whole. from the edge of a steep promontory that commands an inflection of the coast, and of the wall of rock which sweeps round it, i watched for a few seconds the sea,--greatly heightened at the time by the setting in of the flood-tide,--as it broke, surge after surge, against the base of the tall dark precipices; and marked how it accomplished its work of disintegration. the flagstone deposit here abounds in vertical cracks and flaws; and in the line of each of the many fissures which these form the waves have opened up a cave; so that for hundreds of yards together the precipices seem as if founded on arch-divided piers, and remind one of those ancient prints or drawings of old london bridge in which a range of tall sombre buildings is represented as rising high over a line of arches; or of rows of lofty houses in those cities of southern europe in which the dwellings fronting the streets are perforated beneath by lines of squat piazzas, and present above a dingy and windowless breadth of wall. in course of time the piers attenuate and give way; the undermined precipices topple down, parting from the solid mass behind in those vertical lines by which they are traversed at nearly right angles with their line of stratification; the perpendicular front which they had covered comes to be presented, in consequence, to the sea; its faults and cracks gradually widen into caves, as those of the fallen front had gradually widened at an earlier period; in the lapse of centuries, it too, resigning its place, topples over headlong, an undermined mass; the surge dashes white and furious where the dense rock had rested before; and thus, in its slow but irresistible march, the sea gains upon the land. in the peculiar disposition and character of the prevailing strata of orkney, as certainly as in the power of the tides which sweep athwart its coasts, and the wide extent of sea which, stretching around it, gives the waves scope to gather bulk and momentum, may be found the secret of the extraordinary height to which the surf sometimes rises against its walls of rock. during the fiercer tempests, masses of foam shoot upwards against the precipices, like inverted cataracts, fully two hundred feet over the ordinary tide-level, and, washing away the looser soil from their summits, leaves in its place patches of slaty gravel, resembling that of a common sea-beach. rocks less perpendicular, however great the violence of the wind and sea, would fail to project upwards bodies of surf to a height so extraordinary. but the low angle at which the strata lie, and the rectangularity maintained in relation to their line of bed by the fissures which traverse them, give to the orkney precipices,--remarkable for their perpendicularity and their mural aspect,--exactly the angle against which the waves, as broken masses of foam, beat up to their greatest possible altitude. on a tract of iron-bound coast that skirts the entrance of the cromarty frith i have seen the surf rise, during violent gales from the north-west especially, against one rectangular rock, known as the white rock, fully an hundred feet; while against scarcely any of the other precipices, more sloping, though equally exposed, did it rise more than half that height. chapter xiii. detached fossils--remains of the pterichthys--terminal bones of the coccosteus, etc., preserved--internal skeleton of coccosteus--the shipwrecked sailor in the cave--bishop grahame--his character, as drawn by baillie--his successor--ruins of the bishop's country-house--sub-aërial formation of sandstone--formation near new kaye--inference from such formation--tour resumed--loch of stennis--waters of the loch fresh, brackish, and salt--vegetation varied accordingly--change produced in the flounder by fresh water--the standing stones, second only to stonehenge--their purpose--their appearance and situation--diameter of the circle--what the antiquaries say of it--reference to it in the "pirate"--dr. hibbert's account. we returned to stromness along the edge of the cliffs gradually descending from higher to lower ranges of prepices, and ever and anon detecting ichthyolite beds in the weathered and partially decomposed strata. as the rock moulders into an incoherent clay, the fossils which it envelops become not unfrequently wholly detached from it, so that, on a smart blow dealt by the hammer, they leap out entire, resembling, from the degree of compression which they exhibit, those mimic fishes carved out of plates of ivory or of mother-of-pearl, which are used as counters in some of the games of china or the east indies. the material of which they are composed, a brittle jet, though better suited than the stone to resist the disintegrating influences, is in most cases greatly too fragile for preservation. one may, however, acquire from the fragments a knowledge of certain minute points in the structure of the ancient animals to which they belonged, respecting which specimens of a more robust texture give no evidence. the plates of coccosteus sometimes spring out as unbroken as when they covered the living animal, and, if the necessary skill be not wanting, may be set up in their original order. and i possess specimens of the head of dipterus in which the nearly circular gill-covers may be examined on both surfaces, interior and exterior, and in which the cranial portion shows not only the enamelled plates of the frontal buckler, but also the strange mechanism of the palatal teeth, with the intervening cavities that had lodged both the brain and the occipital part of the spine. the fossils on the top of the cliffs here are chiefly dipterians of the two closely allied genera, diplopterus and osteolepis. a little farther on, i found, on a hill-side in which extensive slate-quarries had once been wrought, the remains of pterichthys existing as mere patches, from which the color had been discharged, but in which the almost human-like outline of both body and arms were still distinctly traceable; and farther on still, where the steep wall of cliffs sinks into a line of grassy banks, i saw in yet another quarry, ichthyolites of all the three great ganoid families so characteristic of the old red,--cephalaspians, dipterians, and acanthodians,--ranged in the three-storied order to which i have already referred as so inexplicable. the specimens, however, though numerous, are not fine. they are resolved into a brittle bituminous coal, resembling hard pitch or black wax, which is always considerably less tenacious than the matrix in which they are inclosed; and so, when laid open by the hammer, they usually split through the middle of the plates and scales, instead of parting from the stone at their surfaces, and resemble, in consequence, those dark, shadow-like profiles taken in indian ink by the limner, which exhibit a correct outline, but no details. we find, however, in some of the genera, portions of the animal preserved that are rarely seen in a state of keeping equally perfect in the ichthyolites of cromarty, moray, or banff,--those terminal bones of the coccosteos, for instance, that were prolonged beyond the plates by which the head and upper parts of the body were covered. wherever the ichthyolites are inclosed in nodules, as in the more southerly counties over which the deposit extends, the nodule terminates, in almost every case, with the massier portions of the organism; for the thinner parts, too inconsiderable to have served as attractive nuclei to the stony matter when the concretion was forming, were left outside its pale, and so have been lost; whereas, in the northern districts of the deposit, where the fossils, as in caithness and orkney, occur in flagstone, these slimmer parts, when the general state of keeping is tolerably good, lie spread out on the planes of the slabs, entire often in their minutest rays and articulations. the numerous coccostei of this quarry exhibit, attached to their upper plates, their long vertebral columns, of many joints, that, depending from the broad dorsal shields of the ichthyolite, remind one of those skeleton fishes one sometimes sees on the shores of a fishing village, in which the bared backbone joints on, cord-like, to the broad plates of the skull. none of the other fishes of the old red sandstone possessed an internal skeleton so decidedly osseous as that of the coccosteus, and none of them presented externally so large an extent of naked skin,--provisions which probably went together. for about three-fifths of the entire length of the animal the surface was unprotected by dermal plates; and the muscles must have found the fulcrums on which they acted in the internal skeleton exclusively. and hence a necessity for greater strength in their interior framework than in that of fishes as strongly fenced round externally by scales or plates as the coleoptera by their elytrine, or the crustacea by their shells. even in the coccosteus, however, the ossification was by no means complete; and the analogies of the skeleton seem to have allied it rather with the skeletons of the sturgeon family than with the skeletons of the sharks or rays. the processes of the vertebræ were greatly more solid in their substance than the vertebræ themselves,--a condition which in the sharks and rays is always reversed; and they frequently survive, each with its little sprig of bone, formed like the letter y, that attached it to its centrum, projecting from it, in specimens from which the vertebral column itself has wholly disappeared. i found frequent traces, during my exploratory labors in orkney, of the dorsal and ventral fins of this ichthyolite; but no trace whatever of the pectorals or of the caudal fin. there seem to have been no pectorals; and the tail, as i have always had occasion to remark, was apparently a mere point, unfurnished with rays. in descending from the cliffs upon the quarries, my companion pointed to an angular notch in the rock-edge, apparently the upper termination of one of the numerous vertical cracks by which the precipices are traversed, and which in so many cases on the orkney coast have been hollowed by the waves into long open coves or deep caverns. it was up there, he said, that about twelve years ago the sole survivor of a ship's crew contrived to scramble, four days after his vessel had been dashed to fragments against the rocks below, and when it was judged that all on board had perished. the vessel was wrecked on a wednesday. she had been marked, when in the offing, standing for the bay of stromness; but the storm was violent, and the shore a lee one; and as it was seen from the beach that she could scarce weather the headland yonder, a number of people gathered along the cliffs, furnished with ropes, to render to the crew whatever assistance might be possible in the circumstances. human help, however, was to avail them nothing. their vessel, a fine schooner, when within forty yards of the promontory, was seized broadside by an enormous wave, and dashed against the cliff, as one might dash a glass-phial against a stone-wall. one blow completed the work of destruction; she went rolling in entire from keel to mast-head, and returned, on the recoil of the broken surge, a mass of shapeless fragments, that continued to dance idly amid the foam, or were scattered along the beach. but of the poor men, whom the spectators had seen but a few seconds before running wildly about the deck, there remained not a trace; and the saddened spectators returned to their homes to say that all had perished. four days after,--on the morning of the following sabbath,--the sole survivor of the crew, saved, as if by miracle, climbed up the precipice, and presented himself to a group of astonished and terrified country people, who could scarce regard him as a creature of this world. the fissure, which at the top of the cliff forms but a mere angular inflection, is hollowed below into a low-roofed cave of profound depth, into the farther extremity of which the tide hardly ever penetrates. it is floored by a narrow strip of shingly beach; and on this bit of beach, far within the cave, the sailor found himself, half a minute after the vessel had struck and gone to pieces, washed in, he knew not how. two pillows and a few dozen red herrings, which had been swept in along with him, served him for bed and board; a tin cover enabled him to catch enough of the fresh-water droppings of the roof to quench his thirst; several large fragments of wreck that had been jammed fast athwart the opening of the cave broke the violence of the wind and sea; and in that doleful prison, day after day, he saw the tides sink and rise, and lay, when the surf rolled high at the fall of the tide, in utter darkness even at mid-day, as the waves outside rose to the roof, and inclosed him in a chamber as entirely cut off from the external atmosphere as that of a diving bell. he was oppressed in the darkness, every time the waves came rolling in and compressed his modicum of air, by a sensation of extreme heat,--an effect of the condensation; and then, in the interval of recession, and consequent expansion, by a sudden chill. at low ebb he had to work hard in clearing away the accumulations of stone and gravel which had been rolled in by the previous tide, and threatened to bury him up altogether. at length he succeeded, after many a fruitless attempt, in gaining an upper ledge that overhung his prison-mouth; and, by a path on which a goat would scarce have found footing, he scrambled to the top. his name was johnstone; and the cave is still known as "johnstone's cave." such was the narrative of my companion. a little farther on, the undulating bank, into which the cliffs sink, projects into the sea as a flat green promontory, edged with hills of indurated sand, and topped by a picturesque ruin, that forms a pleasing object in the landscape. the ruin is that of a country residence of the bishops of orkney during the disturbed and unhappy reign of scotch episcopacy, and bears on a flat tablet of weathered sandstone the initials of its founder, bishop george grahame, and the date of its erection, . with a green cultivated oasis immediately around it, and a fine open sound, overlooked by the bold, picturesque cliffs of hoy, in front, it must have been, for at least half the year, an agreeable, and, as its remains testify, a not uncomfortable habitation. but i greatly fear scottish clergymen of the establishment, whether presbyterian or episcopalian, when obnoxious, from their position or their tenets, to the great bulk of the scottish people, have not been left, since at least the reformation, to enjoy either quiet or happy lives, however extrinsically favorable the circumstances in which they may have been placed. bishop grahame, only five years after the date of the erection, was tried before the famous general assembly of ; and, being convicted of having "all the ordinar faults of a bishop," he was deposed, and ordered within a limited time "to give tokens of repentance, under paine of excommunication." "he was a curler on the ice on the sabbath day," says baillie,--"a setter of tacks to his sones and grandsones, to the prejudice of the church; he oversaw adulterie; slighted charming; neglected preaching and doing of anie good; and held portions of ministers' stipends for building his cathedral." the concluding portion of his life, after his deposition, was spent in obscurity; nor did his successor in the bishoprick, subsequent to the reëstablishment of episcopacy at the restoration,--bishop honeyman,--close his days more happily. he was struck in the arm by the bullet which the zealot mitchell had intended for archbishop sharp; and the shattered bone never healed; "for, though he lived some years after," says burnet, "_they_ were forced to lay open the wound every year, for an exfoliation;" and his life was eventually shortened by his sufferings. all seemed comfortable enough, and quite quiet enough, in the bishop's country-house to-day. there were two cows quietly chewing the cud in what apparently had been the dignitary's sitting-room, and patiently awaiting the services of a young woman who was approaching at some little distance with a pail. a large gray cat, that had been sunning herself in a sheltered corner of the court-yard, started up at our approach, and disappeared through a slit hole. the sun, now gone far down the sky, shone brightly on shattered gable-tops, and roofless, rough-edged walls, revealing many a flaw and chasm in the yielding masonry; and their shadows fell with picturesque effect on the loose litter, rude implements, and gapped dry-stone fence, of the neglected farm-yard which surrounds the building. i have said that the flat promontory occupied by the ruin is edged by hills of indurated sand. existing in some places as a continuous bed of a soft gritty sandstone, scooped wave-like a-top, and varying from five to eight feet in thickness, they form a curious example of a sub-aërial formation,--the sand of which they are composed having been all blown from the sea-beach, and consolidated by the action of moisture on a calcareous mixture of comminuted shells, which forms from twenty to twenty-five per cent. of their entire mass. i found that the sections of the bed laid open by the encroachments of the sea, were scarce less regularly stratified than those of a subaqueous deposit, and that it was hollowed, where most exposed to the weather, into a number of spherical cells, which gave to those parts of the surface where they lay thickest, somewhat the aspect of a rude runic fret-work,--an appearance not uncommon in weathered sandstones. with more time to spare, i could fain have studied the deposit more carefully, in the hope of detecting a few peculiarities of structure sufficient to distinguish sub-aërially-formed from subaqueously-deposited beds of stone. sandstones of sub-aërial formation are of no very unfrequent occurrence among the recent deposits. on the coast of cornwall there are cliffs of considerable height that extend for several miles, and have attained a degree of solidity sufficient to serve the commoner purposes of the architect, which at one time existed as accumulations of blown sand. "it is around the promontory of new kaye," says dr. paris, in an interesting memoir on the subject, "that the most extensive formation of sandstone takes place. here it may be seen in different stages of induration, from a state in which it is too friable to be detached from the rock upon which it reposes, to a hardness so considerable, that it requires a violent blow from a sledge-hammer to break it. buildings are here constructed of it; the church of cranstock is entirely built with it; and it is also employed for various articles of domestic and agricultural uses. the geologist who has previously examined the celebrated specimen from guadaloupe will be struck with the great analogy which it bears to this formation." now, as vast tracts of the earth's surface,--in some parts of the world, as in northern africa, millions of square miles together,--are at present overlaid by accumulations of sand, which have this tendency to consolidate and become lasting sub-aërial formations, destined to occupy a place among the future strata of the globe, it seems impossible but that also in the old geologic periods there must have been, as now, sand-wastes and sub-aërial formations. and as the representatives of these may still exist in some of our sandstone quarries, it might be well to be possessed of a knowledge of the peculiarities by which they are to be distinguished from deposits of subaqueous origin. in order that i might have an opportunity of studying these peculiarities where they are to be seen more extensively developed than elsewhere on the eastern coast of scotland, i here formed the intention of spending a day, on my return south, among the sand-wastes of moray,--a purpose which i afterwards carried into effect. but of that more anon. on the following morning, availing myself of a kind invitation, through dr. garson, from his brother, a free church minister resident in an inland district of the mainland, in convenient neighborhood with the northern coasts of the island, and with several quarries, i set out from stromness, taking in my way the loch and standing stones of stennis, which i had previously seen from but my seat in the mail-gig as i passed. mr. learmonth, who had to visit some of his people in this direction, accompanied me for several miles along the shores of the loch, and lightened the journey by his interesting snatches of local history, suggested by the various objects that lay along our road,--buildings, tumuli, ancient battle-fields, and standing stones. the loch itself, an expansive sheet of water fourteen miles in circumference, i contemplated with much interest, and longed for an opportunity of studying its natural history. two promontories,--those occupied by the standing stones, shoot out from the opposite sides, and approach so near as to be connected by a rustic bridge. they divide the loch into two nearly equal parts, the lower of which gives access to the sea, and is salt in its nether reaches and brackish in its upper ones, while the higher is merely brackish in its nether reaches, and fresh enough in its upper ones to be potable. the shores of both were strewed, at the time i passed, by a line of wrack, consisting, for the first few miles, from where the lower loch opens to the sea, of only marine plants, then of marine plants mixed with those of fresh-water growth, and then, in the upper sheet of water, of lacustrine plants exclusively. and the fauna of the loch, like its flora, is, i was led to understand, of the same mixed character; the marine and fresh-water animals having each their own reaches, with certain debatable tracts between, in which each expatiates with more or less freedom, according to its nature and constitution,--some of the sea-fishes advancing far on the fresh water, and others, among the proper denizens of the lake, encroaching far on the salt. the common fresh-water eel strikes out, i was told, farthest into the sea-water; in which, indeed, reversing the habits of the salmon, it is known in various places to deposit its spawn; it seeks, too, impatient of a low temperature, to escape from the cold of winter, by taking refuge in water brackish enough in a climate such as ours to resist the influence of frost. of the marine fishes; on the other hand, i found that the flounder got greatly higher than any of the others, inhabiting reaches of the lake almost entirely fresh. a memoir on the loch of stennis and its productions, animal and vegetable, such as a gilbert white of selborne could produce, would be at once a very valuable and very curious document. by dividing it into reaches, in which the average saltness of the water was carefully ascertained, and its productions noted, with the various modifications which these underwent as they receded upwards or downwards from their proper habitat towards the line at which they could no longer exist, much information might be acquired, of a kind important to the naturalist, and not without its use to the geological student. i have had an opportunity elsewhere of observing a curious change which fresh-water induces on the flounder. in the brackish water of an estuary it becomes, without diminishing in general size, thicker and more fleshy than when in its legitimate habitat the sea; but the flesh loses in quality what it gains in quantity;--it is flabby and insipid, and the margin-fin lacks always its delicious strip of transparent fat. i fain wish that some intelligent resident on the shores of stennis would set himself carefully to examine its productions, and that then, after registering his observations for a few years, he would favor the world with its natural history. the standing stones,--second in britain of their kind, to only those of stonehenge,--occur in two groups; the smaller group (composed, however, of the taller stones) on the southern promontory; the larger on the northern one. rude and shapeless, and bearing no other impress of the designing faculty than that they are stuck endwise in the earth, and form, as a whole, regular figures on the sward, there is yet a sublime solemnity about them, unsurpassed in effect by any ruin i have yet seen, however grand in its design or imposing in its proportions. their very rudeness, associated with their ponderous bulk and weight, adds to their impressiveness. when there is art and taste enough in a country to hew an ornate column, no one marvels that there should also be mechanical skill enough in it to set it up on end; but the men who tore from the quarry these vast slabs, some of them eighteen feet in height over the soil, and raised them where they now stand, must have been ignorant savages, unacquainted with machinery, and unfurnished, apparently, with a single tool. and what, when contemplating their handiwork, we have to subtract in idea from their minds, we add, by an involuntary process, to their bodies: we come to regard the feats which they have accomplished as performed by a power not mechanical, but gigantic. the consideration, too, that these remains,--eldest of the works of man in this country,--should have so long survived all definite tradition of the purposes which they were raised to serve, so that we now merely know regarding them that they were religious in their uses,--products of that ineradicable instinct of man's nature which leads him in so many various ways to attempt conciliating the powers of another world,--serves greatly to heighten their effect. history at the time of their erection had no existence in these islands: the age, though it sought, through the medium of strange, unknown rites, to communicate with heaven, was not knowing enough to communicate, through the medium of alphabet or symbol, with posterity. the appearance of the obelisks, too, harmonizes well with their great antiquity and the obscurity of their origin. for about a man's height from the ground they are covered thick by the shorter lichens,--chiefly the gray-stone parmelia,--here and there embroidered by golden-hued patches of the yellow parmelia of the wall; but their heads and shoulders, raised beyond the reach alike of the herd-boy and of his herd, are covered by an extraordinary profusion of a flowing beard-like lichen of unusual length,--the lichen _calicarus_ (or, according to modern botanists, _ramalina scopulorum_), in which they look like an assemblage of ancient druids, mysteriously stern and invincibly silent and shaggy as the bard of gray, when "loose his beard and hoary hair streamed like a meteor on the troubled air." the day was perhaps too sunny and clear for seeing the standing stones to the best possible advantage. they could not be better placed than on their flat promontories, surrounded by the broad plane of an extensive lake, in a waste, lonely, treeless country, that presents no bold, competing features to divert attention from them as the great central objects of the landscape; but the gray of the morning, or an atmosphere of fog and vapor, would have associated better with the mystic obscurity of their history, their shaggy forms, and their livid tints, than the glare of a cloudless sun, that brought out in hard, clear relief their rude outlines, and gave to each its sharp dark patch of shadow. gray-colored objects, when tall and imposing, but of irregular form, are seen always to most advantage in an uncertain light,--in fog or frost-rime, or under a scowling sky, or, as parnell well expresses it, "amid the living gleams of night." they appeal, if i may so express myself, to the sentiment of the ghostly and the spectral, and demand at least a partial envelopment of the obscure. burns, with the true tact of the genuine poet, develops the sentiment almost instinctively in an exquisite stanza in one of his less-known songs, "the posey,"-- "the hawthorn i will pu', _wi' its locks o' siller gray_, where, _like an aged man, it stands at break o' day_." scott, too, in describing these very stones, chooses the early morning as the time in which to exhibit them, when they "stood in the gray light of the dawning, like the phantom forms of antediluvian giants, who, shrouded in the habiliments of the dead, come to revisit, by the pale light, the earth which they had plagued with their oppression, and polluted by their sins, till they brought down upon it the vengeance of long-suffering heaven." on another occasion, he introduces them as "glimmering, a grayish white, in the rising sun, and projecting far to the westward their long gigantic shadows." and malcolm, in the exercise of a similar faculty with that of burns and of scott, surrounds them, in his description, with a somewhat similar atmosphere of partial dimness and obscurity:-- "the hoary rocks, of giant size, that o'er the land in circles rise, of which tradition may not tell, fit circles for the wizard's spell, seen far _amidst the scowling storm_, seem each a tall and phantom form, _as hurrying vapors o'er them flee,_ frowning in grim security, while, like a dread voice from the past, around them moans the autumnal blast." there exist curious analogies between the earlier stages of society and the more immature periods of life,--between the savage and the child; and the huge circle of stennis seems suggestive of one of these. it is considerably more than four hundred feet in diameter, and the stones which compose it, varying from three to fourteen feet in height, must have been originally from thirty-five to forty in number, though only sixteen now remain erect. a mound and fosse, still distinctly traceable, run round the whole; and there are several mysterious-looking tumuli outside, bulky enough to remind one of the lesser morains of the geologist. but the circle, notwithstanding its imposing magnitude, is but a huge child's house, after all,--one of those circles of stones which children lay down on their village green, and then, in the exercise of that imaginative faculty which distinguishes between the young of the human animal and those of every other creature, convert, by a sort of conventionalism, into a church or dwelling-house, within which they seat themselves, and enact their imitations of their seniors, whether domestic or ecclesiastical. the circle of stennis was a circle, say the antiquaries, devoted to the sun. the group of stones on the southern promontory of the lake formed but a half-circle, and it was a half-circle dedicated to the moon. to the circular sun the great rude children of an immature age of the world had laid down a circle of stones on the one promontory; to the moon, in her half-orbed state, they had laid down a half-circle on the other; and in propitiating these material deities, to whose standing in the old scandinavian worship the names of our _sun_day and _mon_day still testify, they employed in their respective inclosures, in the exercise of a wild unregulated fancy, uncouth irrational rites, the extremeness of whose folly was in some measure concealed by the horrid exquisiteness of their cruelty. we are still in the nonage of the species, and see human society sowing its wild oats in a thousand various ways, very absurdly often, and often very wickedly; but matters seem to have been greatly worse when, in an age still more immature, the grimly-bearded, six-feet children of orkney were laying down their stone-circles on the green. sir walter, in the parting scene between cleveland and minna troil, which he describes as having taken place amid the lesser group of stones, refers to an immense slab "lying flat and prostrate in the middle of the others, supported by short pillars, of which some relics are still visible," and which is regarded as the sacrificial stone of the erection. "it is a current belief," says dr. hibbert, in an elaborate paper in the "transactions of the scottish antiquaries," that upon this stone a victim of royal birth was immolated. halfdan the long-legged, the son of harold the fair-haired, in punishment for the aggressions of orkney, had made an unexpected descent upon its coasts, and acquired possession of the jarldom. in the autumn succeeding halfdan was retorted upon, and, after an inglorious contest, betook himself to a place of concealment, from which he was the following morning unlodged, and instantly doomed to the asæ. einar, the jarl of orkney, with his sword carved the captive's back into the form of an eagle, the spine being longitudinally divided, and the ribs being separated by a transverse cut as far as the loins. he then extracted the lungs, and dedicated them to odin for a perpetuity of victory, singing a wild song,--'i am revenged for the slaughter of rognvalld: this have the nornæ decreed. in my fiording the pillar of the people has fallen. build up the cairn, ye active youths, for victory is with us. from the stones of the sea-shore will i pay the long-legged a hard seat.' there is certainly no trace to be detected, in this dark story, of a golden age of the world: the golden age is, i would fain hope, an age yet to come. there at least exists no evidence that it is an age gone by. it will be the full-grown _manly_ age of the world when the race, as such, shall have attained to their years of discretion. they are at present in their froward boyhood, playing at the mischievous games of war, and diplomacy, and stock-gambling, and site-refusing, and it is not quite agreeable for quiet honest people to be living amongst them. but there would be nothing gained by going back to that more infantine state of society in which the jarl einar carved into a red eagle the back of halfdan the long-legged. chapter xiv. on horseback--a pared moor--small landholders--absorption of small holdings in england and scotland--division of land favorable to civil and religious rights--favorable to social elevation--an inland parish--the landsman and lobster--wild flowers of orkney--law of compensation illustrated by the tobacco plant--poverty tends to productiveness--illustrated in ireland--profusion of ichthyolites--orkney a land of defunct fishes--sandwick--a collection of coccostean flags--a quarry full of heads of dipteri--the bergil, or striped wrasse--its resemblance to the dipterus--poverty of the flora of the lower old red--no true coniferous wood in the orkney flagstones--departure for hoy--the intelligent boatman--story of the orkney fisherman. while yet lingering amid the standing stones, i was joined by mr. garson, who had obligingly ridden a good many miles to meet me, and now insisted that i should mount and ride in turn, while he walked by my side, that i might be fresh, he said, for the exploratory ramble of the evening. i could have ventured more readily on taking the command of a vessel than of a horse, and with fewer fears of mutiny; but mount i did; and the horse, a discreet animal, finding he was to have matters very much his own way, got upon honor with me, and exerted himself to such purpose that we did not fall greatly more than a hundred yards behind mr. garson. we traversed in our journey a long dreary moor, so entirely ruined, like those which i had seen on the previous day, by belonging to everybody in general, as to be no longer of the slightest use to anybody in particular. the soil seems to have been naturally poor; but it must have taken a good deal of spoiling to render it the sterile, verdureless waste it is now; for even where it had been poorest, i found that in the island-like appropriated patches by which it is studded, it at least bears, what it has long ceased to bear elsewhere, a continuous covering of green sward. but if disposed to quarrel with the commons of orkney, i found in close neighborhood with them that with which i could have no quarrel,--numerous small properties farmed by the proprietors, and forming, in most instances, farms by no means very large. there are parishes in this part of the mainland divided among from sixty to eighty landowners. a nearly similar state of things seems to have obtained in scotland about the beginning of the eighteenth century, and for the greater part of the previous one. i am acquainted with old churchyards in the north of scotland that contain the burying-grounds of from six to ten landed proprietors, whose lands are now merged into single properties. and, in reading the biographies of our old covenanting ministers, i have often remarked as curious, and as bearing in the same line, that no inconsiderable proportion of their number were able to retire, in times of persecution, to their own little estates. it was during the disastrous wars of the french revolution,--wars from the effects of which great britain will, i fear, never fully recover,--that the smaller holdings were finally absorbed. about twenty years ere the war began, the lands of england were parcelled out among no fewer than two hundred and fifty thousand families; before the peace of , they had fallen into the hands of thirty-two thousand. in less than half a century, that base of actual proprietorship on which the landed interest of any country must ever find its surest standing, had contracted in england to less than one-seventh its former extent. in scotland the absorption of the great bulk of the lesser properties seems to have taken place somewhat earlier; but in it also the revolutionary war appears to have given them the final blow; and the more extensive proprietors of the kingdom are assuredly all the less secure in consequence of their extinction. they were the smaller stones in the wall, that gave firmness in the setting to the larger, and jammed them fast within those safe limits determined by the line and plummet, which it is ever perilous to overhang. very extensive territorial properties, wherever they exist, create almost necessarily--human nature being what it is--a species of despotism more oppressive than even that of great unrepresentative governments. it used to be remarked on the continent, that there was always less liberty in petty principalities, where the eye of the ruler was ever on his subjects, than under the absolute monarchies.[ ] and in a country such as ours, the accumulation of landed property in the hands of comparatively a few individuals has the effect often of bringing the territorial privileges of the great landowner into a state of antagonism with the civil and religious rights of the people, that cannot be other than perilous to the landowner himself. in a district divided, like orkney, among many owners, a whole country-side could not be shut up against its people by some ungenerous or intolerant proprietor,--greatly at his own risk and to his own hurt,--as in the case of glen tilt or the grampians; nor, when met for purposes of public worship, could the population of a parish be chased from off its bare moors, at his instance, by the constable or the sheriff-officer, to worship god agreeably to their consciences amid the mire of a cross-road, or on the bare sea-beach uncovered by the ebb of the tide. the smaller properties of the country, too, served admirably as stepping-stones, by which the proprietors or their children, when possessed of energy and intellect, could mount to a higher walk of society. here beside me, for instance, was my friend mr. garson, a useful and much-esteemed minister of religion in his native district; while his brother, a medical man of superior parts, was fast rising into extensive practice in the neighboring town. they had been prepared for their respective professions by a classical education; and yet the stepping-stone to positions in society at once so important and so respectable was simply one of the smaller holdings of orkney, derived to them as the descendants of one of the old scandinavian udallers, and which fell short, i was informed, of a hundred a-year. mr. garson's dwelling, to which i was welcomed with much hospitality by his mother and sisters, occupies the middle of an inclined hollow or basin, so entirely surrounded by low, moory hills, that at no point,--though the radius of the prospect averages from four to six miles,--does it command a view of the sea. i scarce expected being introduced in orkney to a scene in which the traveller could so thoroughly forget that he was on an island. of the parish of harray, which borders on mr. garson's property, no part touches the sea-coast; and the people of the parish are represented by their neighbors, who pride themselves upon their skill as sailors and boatmen, as a race of lubberly landsmen, unacquainted with nautical matters, and ignorant of the ocean and its productions. a harray man is represented, in one of their stories, as entering into a compact of mutual forbearance with a lobster,--to him a monster of unknown powers and formidable proportions,--which he had at first attempted to capture, but which had shown fight, and had nearly captured him in turn. "weel, weel, let a-be for let a-be," he is made to say; "if thou does na clutch me in thy grips, i'se no clutch thee in mine." it is to this primitive parish that david vedder, the sailor-poet of orkney, refers, in his "orcadian sketches," as "celebrated over the whole archipelago for the peculiarities of its inhabitants, their singular manners and habits, their uncouth appearance, and homely address. being the most landward district in pomona," he adds, "and consequently having little intercourse with strangers, it has become the stronghold of many ancient customs and superstitions, which modern innovation has pushed off from their pedestals in almost all the other parts of the island. the permanency of its population, too, is mightily in favor of 'old use and wont,' as it is almost entirely divided amongst a class of men yelept _pickie_, or petty lairds, each ploughing his own fields and reaping his own crops, much in the manner their great-great-grandfathers did in the days of earl patrick. and such is the respect which they entertain for their hereditary beliefs, that many of them are said still to cast a lingering look, not unmixed with reverence, on certain spots held sacred by their scandinavian ancestors." after an early dinner i set out for the barony of birsay, in the northern extremity of the mainland, accompanied by mr. garson, and passed for several miles over a somewhat dreary country, bare, sterile, and brown, studded by cold, broad, treeless lakes, and thinly mottled by groups of gray, diminutive cottages, that do not look as if there was much of either plenty or comfort inside. but after surmounting the hills that form the northern side of the interior basin, i was sensible of a sudden improvement on the face of the country. where the land slopes towards the sea, the shaggy heath gives place to a green luxuriant herbage; and the frequent patches of corn seem to rejoice in a more genial soil. the lower slopes of orkney are singularly rich in wild flowers,--richer by many degrees than the fat loamy meadows of england. they resemble gaudy pieces of carpeting, as abundant in petals as in leaves: their luxuriant blow of red and white, blue and yellow, seems as if competing, in the extent of surface which it occupies, with their general ground of green. i have remarked a somewhat similar luxuriance of wild flowers in the more sheltered hollows of the bleak north-western coasts of scotland. there is little that is rare to be found among these last, save that a few alpine plants may be here and there recognized as occurring at a lower level than elsewhere in britain; but the vast profusion of blossoms borne by species common to the greater part of the kingdom imparts to them an apparently novel character. we may detect, i am inclined to think, in this singular profusion, both in orkney and the bleaker districts of the mainland of scotland, the operation of a law not less influential in the animal than in the vegetable world, which, when hardship presses upon the life of the individual shrub or quadruped, so as to threaten its vitality, renders it fruitful in behalf of its species. i have seen the principle strikingly exemplified in the common tobacco plant, when reared in a northern country in the open air. year after year it continued to degenerate, and to exhibit a smaller leaf and a shorter stem, until the successors of what in the first year of trial had been vigorous plants of from three to four feet in height, had in the sixth or eighth become mere weeds of scarce as many inches. but while the more flourishing, and as yet undegenerate plant, had merely borne a-top a few florets, which produced a small quantity of exceedingly minute seeds, the stunted weed, its descendant, was so thickly covered over in its season with its pale yellow bells, as to present the appearance of a nosegay; and the seeds produced were not only bulkier in the mass, but also individually of much greater size. the tobacco had grown productive in proportion as it had degenerated and become poor. in the common scurvy grass, too, remarkable, with some other plants, as i have already had occasion to mention, for taking its place among both the productions of our alpine heights and of our sea-shores, it will be found that in proportion as its habitat proves ungenial, and its stems and leaves become dwarfish and thin, its little white cruciform flowers increase, till, in localities where it barely exists, as if on the edge of extinction, we find the entire plant forming a dense bundle of seed-vessels, each charged to the full with seed. and in the gay meadows of orkney, crowded with a vegetation that approaches its northern limit of production, we detect what seems to be the same principle, chronically operative; and hence, it would seem, their extraordinary gaiety. their richly-blossoming plants are the poor productive _irish_ of the vegetable world;[ ] for doubleday seems to be quite in the right in holding that the law extends to not only the inferior animals, but to our own species also. the lean, ill-fed sow and rabbit rear, it has been long known, a greatly more numerous progeny than the same animals when well cared for and fat; and every horse and cattle breeder knows, that to over-feed his animals proves a sure mode of rendering them sterile. the sheep, if tolerably well pastured, brings forth only a single lamb at a birth; but if half-starved and lean, the chances are that it may bring forth two or three. and so it is also with the greatly higher human race. place them in circumstances of degradation and hardship so extreme as almost to threaten their existence as individuals, and they increase, as if in behalf of the species, with a rapidity without precedent in circumstances of greater comfort. the aristocratic families of a country are continually running out; and it requires frequent creations to keep up the house of lords; while our poor people seem increasing in some districts in almost the mathematical ratio. the county of sutherland is already more populous than it was previous to the great clearings. in skye, though fully two-thirds of the population emigrated early in the latter half of the last century, a single generation had scarce passed ere the gap was completely filled; and miserable ireland, had the human family no other breeding-place or nursery, would of itself be sufficient in a very few ages to people the world. we returned, taking in our way the cliffs of marwick head, in which i detected a few scattered plates and scales, and which, like nine-tenths of the rocks of orkney, belong to the great flagstone division of the formation. i found the dry-stone fences on mr. garson's property still richer in detached fossil fragments than the cliffs; but there are few erections in the island that do not inclose in their walls portions of the organic. we find ichthyolite remains in the flagstones laid bare along the way-side,--in every heap of road-metal,--in the bottom of every stream,--in almost every cottage and fence. orkney is a land of defunct fishes, and contains in its rocky folds more individuals of the waning ganoid family than are now to be found in all the existing seas, lakes, and rivers of the world. i enjoyed in a snug upper room a delectable night's rest, after a day of prime exercise, prolonged till it just touched on toil, and again experienced, on looking out in the morning on the wide flat basin around, a feeling somewhat akin to wonder, that orkney should possess a scene at once so extensive and so exclusively inland. towards mid-day i walked on to the parish manse of sandwick, armed with a letter of introduction to its inmate, the rev. charles clouston,--a gentleman whose descriptions of the orkneys, in the very complete and tastefully written guide-book of the messrs. anderson of inverness, and of his own parish in the "statistical account of scotland," had, both from the high literary ability and the amount of scientific acquirement which they exhibit, rendered me desirous to see. i was politely received, though my visit must have been, as i afterwards ascertained, at a rather inconvenient time. it was now late in the week, and the coming sabbath was that of the communion in the parish; but mr. clouston obligingly devoted to me at least an hour, and i found it a very profitable one. he showed me a collection of flags, with which he intended constructing a grotto, and which contained numerous specimens of coccosteus, that he had exposed to the weather, to bring out the fine blue efflorescence,--a phosphate of iron which forms on the surface of the plates. they reminded me, from their peculiar style of coloring, and the grotesqueness of their forms, of the blue figuring on pieces of buff-colored china, and seemed to be chiefly of one species, very abundant in orkney, the _coccosteus decipiens_. we next walked out to see a quarry in the neighborhood of the manse, remarkable for containing in immense abundance the heads of dipteri,--many of them in a good state of keeping, with all the multitudinous plates to which they owe their pseudo-name, polyphractus, in their original places, and bearing unworn and untarnished their minute carvings and delicate enamel, but existing in every case as mere detached heads. i found three of them lying in one little slaty fragment of two and a half inches by four, which i brought along with me. mr. clouston had never seen the curious arrangement of palatal plates and teeth which distinguishes the dipterus; and, drawing his attention to it in an ill-preserved specimen which i found in the coping of his glebe-wall, i restored, in a rude pencil sketch, the two angular patches of teeth that radiate from the elegant dart-head in the centre of the palate, with the rhomboidal plate behind. "we have a fish, not uncommon on the rocky coasts of this part of the country," he said,--"the bergil or striped wrasse (_labras balanus_),--which bears exactly such patches of angular teeth in its palate. they adhere strongly together; and, when found in our old picts' houses, which occasionally happens, they have been regarded by some of our local antiquaries as artificial,--an opinion which i have had to correct, though it seems not improbable that, from their gem-like appearance, they may have been used in a rude age as ornaments. i think i can show you one disinterred here some years ago." it interested me to find, from mr. clouston's specimens that the palatal grinders of this recent fish of orkney very nearly resemble those of its _dipterus_ of the old red sandstone. the group is of nearly the same size in the modern as in the ancient fish, and presents the same angular form; but the individual teeth are more strongly set in the bergil than in the dipterus, and radiate less regularly from the inner rectangular point of the angle to its base outside. i could fain have procured an orkney bergil, in order to determine the general pattern of its palatal dentition with what is very peculiar in the more ancient fish,--the form of the lower jaw; and to ascertain farther, from the contents of the stomach, the species of shell-fish or crustaceans on which it feeds; but, though by no means rare in orkney, where it is occasionally used as food, i was unable, during my short stay, to possess myself of a specimen. mr. clouston had, i found, chiefly directed his palæontological inquiries on the vegetable remains of the flagstones, as the department of the science in which, in relation to orkney, most remained to be done; and his collection of these is the most considerable in the number of its specimens that i have yet seen. it, however, serves but to show how very extreme is the poverty of the flora of the lower old red sandstone. the numerous fishes of the period seem to have inhabited a sea little more various in its vegetation than in its molluscs. among the specimens of mr. clouston's collection i could detect but two species of plants,--an imperfectly preserved vegetable, more nearly resembling a club-moss than aught i have seen, and a smooth-stemmed fucoid, existing as a mere coaly film on the stone, and distinguished chiefly from the other by its sharp-edged, well-defined outline, and from the circumstance that its stems continue to retain the same diameter for a considerable distance, and this, too, after throwing off at acute angles numerous branches, nearly equal in bulk to the parent trunk. in a specimen about two and a half feet in length, which i owe to the kindness of mr. dick of thurso, there are stems continuous throughout, that, though they ramify into from six to eight branches in that space, are quite as thick atop as at bottom. they are the remains, in all probability, of a long flexible fucoid, like those fucoids of the intertropical seas that, streaming slantwise in the tide, rise not unfrequently to the surface in fifteen and twenty fathoms water. i saw among mr. clouston's specimens no such lignite as the fragment of true coniferous wood which i had found at cromarty a few years previous, and which, it would seem, is still unique among the fossils of the old red sandstone. in the chart of the pacific attached to the better editions of "cook's voyages," there are several entries along the track of the great navigator that indicate where, in mid-ocean, trees, or fragments of trees, had been picked up. the entries, however, are but few, though they belong to all the three voyages together: if i remember aright, there are only five entries in all,--two in the northern and three in the southern pacific. the floating tree, at a great distance from land, is of rare occurrence in even the present scene of things, though the breadth of land be great, and trees numerous; and in the times of the old red sandstone, when probably the breadth of land was _not_ great, and trees _not_ numerous, it seems to have been of rarer occurrence still. but it is at least something to know that in this early age of the world trees there were. i walked on to stromness, and on the following morning, that of saturday, took boat for hoy,--skirting, on my passage out, the eastern and southern shores of the intervening island of græmsay, and, on the passage back again, its western and northern shores. the boatman, an intelligent man,--one of the teachers, as i afterwards ascertained, in the free church sabbath-school,--lightened the way by his narratives of storm and wreck, and not a few interesting snatches of natural history. there is no member of the commoner professions with whom i better like to meet than with a sensible fisherman, who makes a right use of his eyes. the history of fishes is still very much what the history of almost all animals was little more than half a century ago,--a matter of mere external description, heavy often and dry, and of classification founded exclusively on anatomical details. we have still a very great deal to learn regarding the character, habits and instincts of these denizens of the deep,--much, in short, respecting that faculty which is in them through which their natures are harmonized to the inexorable laws, and they continue to live wisely and securely, in consequence, within their own element, when man, with all his reasoning ability, is playing strange vagaries in his;--a species of knowledge this, by the way, which constitutes by far the most valuable part,--the _mental_ department of natural history; and the notes of the intelligent fisherman, gleaned from actual observation, have frequently enabled me to fill portions of the wide hiatus in the history of fishes which it ought of right to occupy. in passing, as we toiled along the græmsay coast, the ruins of a solitary cottage, the boatman furnished us with a few details of the history and character of its last inmate, an orkney fisherman, that would have furnished admirable materials for one of the darker sketches of crabbe. he was, he said, a resolute, unsocial man, not devoid of a dash of reckless humor, and remarkable for an extraordinary degree of bodily strength, which he continued to retain unbroken to an age considerably advanced, and which, as he rarely admitted of a companion in his voyages, enabled him to work his little skiff alone, in weather when even better equipped vessels had enough ado to keep the sea. he had been married in early life to a religiously-disposed woman, a member of some dissenting body; but, living with him in the little island of græmsay, separated by the sea from any place of worship, he rarely permitted her to see the inside of a church. at one time, on the occasion of a communion sabbath in the neighboring parish of stromness, he seemed to yield to her entreaties, and got ready his yawl, apparently with the design of bringing her across the sound to the town. they had, however, no sooner quitted the shore than he sailed off to a green little ogygia of a holm in the neighborhood, on which, reversing the old mythologic story of calypso and ulysses, he incarcerated the poor woman for the rest of the day till evening. i could see, from the broad grin with which the boatman greeted this part of the recital, that there was, unluckily, almost fun enough in the trick to neutralize the sense of its barbarity. the unsocial fisherman lived on, dreaded and disliked, and yet, when his skiff was seen boldly keeping the sea in the face of a freshening gale, when every other was making for port, or stretching out from the land as some stormy evening was falling, not a little admired also. at length, on a night of fearful tempest, the skiff was marked approaching the coast, full on an iron-bound promontory, where there could be no safe landing. the helm, from the steadiness of her course, seemed fast lashed, and, dimly discernible in the uncertain light, the solitary boatman could be seen sitting erect at the bows, as if looking out for the shore. but as his little bark came shooting inwards on the long roll of a wave, it was found that there was no speculation in his stony glance: the misanthropic fisherman was a cold and rigid corpse. he had died at sea, as english juries emphatically express themselves in such cases, under "the visitation of god." chapter xv. hoy--unique scenery--the dwarfie stone of hoy--sir walter scott's account of it--its associations--inscription of names--george buchanan's consolation--the mythic carbuncle of the hill of hoy--no fossils at hoy--striking profile of sir walter scott on the hill of hoy--sir walter, and shetland and orkney--originals of two characters in "the pirate"--bessie millie--garden of gow, the "pirate"--childhood's scene of byron's "torquil"--the author's introduction to his sister--a german visitor--german and scotch sabbath-keeping habits contrasted--mr. watt's specimens of fossil remains--the only new organism found in orkney--back to kirkwall--to wick--vedder's ode to orkney. we landed at hoy, on a rocky stretch of shore, composed of the gray flagstones of the district. they spread out here in front of the tall hills composed of the overlying sandstone, in a green undulating platform, resembling a somewhat uneven esplanade spread out in front of a steep rampart. with the upper deposit a new style of scenery commences, unique in these islands: the hills, bold and abrupt, rise from fourteen to sixteen hundred feet over the sea-level; and the valleys by which they are traversed,--no mere shallow inflections of the general surface, like most of the other valleys of orkney,--are of profound depth, precipitous, imposing, and solitary. the sudden change from the soft, low, and comparatively tame, to the bold, stern, and high, serves admirably to show how much the character of a landscape may depend on the formation which composes it. a walk of somewhat less than two miles brought me into the depths of a brown, shaggy valley, so profoundly solitary, that it does not contain a single human habitation, nor, with one interesting exception, a single trace of the hand of man. as the traveller approaches by a path somewhat elevated, in order to avoid the peaty bogs of the bottom, along the slopes of the northern side of the dell, he sees, amid the heath below, what at first seems to be a rhomboidal piece of pavement of pale old red sandstone, bearing atop a few stunted tufts of vegetation. there are no neighboring objects of a known character by which to estimate its size; the precipitous hill-front behind is more than a thousand feet in height: the greatly taller ward hill of hoy, which frowns over it on the opposite side, is at least five hundred feet higher; and, dwarfed by these giants, it seems a mere pavior's flag, mayhap some five or six feet square, by from eighteen inches to two feet in depth. it is only on approaching it within a few yards that we find it to be an enormous stone, nearly thirty feet in length by almost fifteen feet in breadth, and in some places, though it thins, wedge-like, towards one of the edges, more than six feet in thickness,--forming altogether such a mass as the quarrier would detach from the solid rock to form the architrave of some vast gateway, or the pediment of some colossal statue. a cave-like excavation, nearly three feet square, and rather more than seven feet in depth, opens on its gray and lichened side. the excavation is widened within, along the opposite walls, into two uncomfortably short beds, very much resembling those of the cabin of a small coasting vessel. one of the two is furnished with a protecting ledge and a pillow of stone, hewn out of the solid mass, while the other, which is some five or six inches shorter than its neighbor, and presents altogether more the appearance of a place of penance than of repose, lacks both cushion and ledge. an aperture, which seems to have been originally of a circular form, and about two and a half feet in diameter, but which some unlucky herd-boy, apparently in the want of better employment, has considerably mutilated and widened, opens at the inner excavation of the extremity to the roof, as the hatch of a vessel opens from the hold to the deck; for it is by far too wide in proportion to the size of the apartment to be regarded as a chimney. a gray, rudely-hewn block of sandstone, which, though greatly too ponderous to be moved by any man of the ordinary strength, seems to have served the purpose of a door, lies prostrate beside the opening in front. and such is the famous dwarfie stone of hoy, as firmly fixed in our literature by the genius of sir walter scott, as in this wild valley by its ponderous weight and breadth of base, and regarding which--for it shares in the general obscurity of the other ancient remains of orkney--the antiquary can do little more than repeat, somewhat incredulously, what tradition tells him, viz., that it was the work, many ages ago, of an ugly, malignant goblin, half-earth half-air,--the elfin trolld,--a personage, it is said, that even within the last century, used occasionally to be seen flitting about in its neighborhood. i was fortunate in a fine breezy day, clear and sunshiny, save where the shadows of a few dense piled-up clouds swept dark athwart the landscape. in the secluded recesses of the valley all was hot, heavy and still; though now and then a fitful snatch of a breeze, the mere fragment of some broken gust that seemed to have lost its way, tossed for a moment the white cannach of the bogs, or raised spirally into the air, for a few yards, the light beards of some seeding thistle, and straightway let them down again. suddenly, however, about noon, a shower broke thick and heavy against the dark sides and gray scalp of the ward hill, and came sweeping down the valley. i did what norna of the fitful head had, according to the novelist, done before me in similar circumstances, crept for shelter into the larger bed of the cell, which, though rather scant, taken fairly lengthwise, for a man of five feet eleven, i found, by stretching myself diagonally from corner to corner, no very uncomfortable lounging-place in a thunder-shower. some provident herd-boy had spread it over, apparently months before, with a littering of heath and fern, which now formed a dry, springy conch; and as i lay wrapped up in my plaid, listening to the rain-drops as they pattered thick and heavy atop, or slanted through the broken hatchway to the vacant bed on the opposite side of the excavation, i called up the wild narrative of norna, and felt all its poetry. the opening passage of the story is, however, not poetry, but good prose, in which the curious visitor might give expression to his own conjectures, if ingenious enough either to form or to express them so well. "with my eyes fixed on the smaller bed," the sorceress is made to say, "i wearied myself with conjectures regarding the origin and purpose of my singular place of refuge. had it been really the work of that powerful trolld to whom the poetry of the scalds referred it? or was it the tomb of some scandinavian chief, interred with his arms and his wealth, perhaps also with his immolated wife, that what he loved best in life might not in death be divided from him? or was it the abode of penance chosen by some devoted anchorite of later days? or the idle work of some wandering mechanic, whom chance, and whim, and leisure, had thrust upon such an undertaking?" what follows this sober passage is the work of the poet. "sleep," continues norna, "had gradually crept upon me among my lucubrations, when i was startled from my slumbers by a second clap of thunder, and when i awoke, i saw through the dim light which the upper aperture admitted, the unshapely and indistinct form of trolld the dwarf, seated opposite to me on the lesser couch, which his square and misshapen bulk seemed absolutely to fill up. i was startled, but not affrighted; for the blood of the ancient race of lochlin was warm in my veins. he spoke, and his words were of norse,--so old, that few save my father, or i myself could have comprehended their import,--such language as was spoken in these islands ere olave planted his cross on the ruins of heathenism. his meaning was dark also, and obscure, like that which the pagan priests were wont to deliver, in the name of their idols, to the tribes that assembled at the _helgafels_.... i answered him in nearly the same strain, for the spirit of the ancient scalds of our race was upon me; and far from fearing the phantom with whom i sat cooped within so narrow a space, i felt the impulse of that high courage which thrust the ancient champions and druidesses upon contests with the invisible world, when they thought that the earth no longer contained enemies worthy to be subdued by them.... the demon scowled at me as if at once incensed and overawed; and then, coiling himself up in a thick and sulphurous vapor, he disappeared from his place. i did not till that moment feel the influence of fright, but then it seized me. i rushed into the open air, where the tempest had passed away, and all was pure and serene." shall i dare confess, that i could fain have passed some stormy night all alone in this solitary cell, were it but to enjoy the luxury of listening, amid the darkness, to the clashing rain and the roar of the wind high among the cliffs, or to detect the brushing sound of hasty footsteps in the wild rustle of the heath, or the moan of unhappy spirits in the low roar of the distant sea. or, mayhap,--again to borrow from the poet,--as midnight was passing into morning, "to ponder o'er some mystic lay, till the wild tale had all its sway; and in the bittern's distant shriek i heard unearthly voices speak, or thought the wizard priest was come to claim again his ancient home! and bade my busy fancy range to frame him fitting shape and strange; till from the dream my brow i cleared, and smiled to think that i had feared." the dwarfie stone has been a good deal undervalued by some writers, such as the historian of orkney, mr. barry; and, considered simply as a work of art or labor, it certainly does not stand high. when tracing, as i lay a-bed, the marks of the tool, which, in the harder portions of the stone, are still distinctly visible, i just thought how that, armed with pick and chisel, and working as i was once accustomed to work, i could complete such another excavation to order in some three weeks or a month. but then, i could not make my excavation a thousand years old, nor envelop its origin in the sun-gilt vapors of a poetic obscurity, nor connect it with the supernatural, through the influences of wild ancient traditions, nor yet encircle it with a classic halo, borrowed from the undying inventions of an exquisite literary genius. a half-worn pewter spoon, stamped on the back with the word _london_, which was found in a miserable hut on the banks of the awatska by some british sailors, at once excited in their minds a thousand tender remembrances of their country. and it would, i suspect, be rather a poor criticism, and scarcely suited to grapple with the true phenomena of the case, that, wholly overlooking the magical influences of the associative faculty, would concentrate itself simply on either the-workmanship or the materials of the spoon. nor is the dwarfie stone to be correctly estimated, independently of the suggestive principle, on the rules of the mere quarrier who sells stones by the cubic foot, or of the mere contractor for hewn work who dresses them by the square one. the pillow i found lettered over with the names of visitors; but the stone,--an exceedingly compact red sandstone,--had resisted the imperfect tools at the command of the traveller,--usually a nail or knife; and so there were but two of the names decipherable,--that of an "h. ross, ," and that of a "p. folster, ." the rain still pattered heavily overhead; and with my geological chisel and hammer i did, to beguile the time, what i very rarely do,--added my name to the others, in characters which, if both they and the dwarfie stone get but fair play, will be distinctly legible two centuries hence. in what state will the world then exist, or what sort of ideas will fill the head of the man who, when the rock has well-nigh yielded up its charge, will decipher the name for the last time, and inquire, mayhap, regarding the individual whom it now designates, as i did this morning, when i asked, "who was this h. ross, and who this p. folster?" i remember when it would have saddened me to think that there would in all probability be as little response in the one case as in the other; but as men rise in years they become more indifferent than in early youth to "that life which wits inherit after death," and are content to labor on and be obscure. they learn, too, if i may judge from experience, to pursue science more exclusively for its own sake, with less, mayhap, of enthusiasm to carry them on, but with what is at least as strong to take its place as a moving force, that wind and bottom of formed habit through which what were at first acts of the will pass into easy half-instinctive promptings of the disposition. in order to acquaint myself with the fossiliferous deposits of scotland, i have travelled, hammer in hand, during the last nine years, over fully ten thousand miles; nor has the work been in the least one of dry labor,--not more so than that of the angler, or grouse-shooter, or deer-stalker: it has occupied the mere leisure interstices of a somewhat busy life, and has served to relieve its toils. i have succeeded, however, in accomplishing but little: besides, what is discovery to-day will be but rudimentary fact to the tyro-geologists of the future. but if much has not been done, i have at least the consolation of george buchanan, when, according to melvill, "fand sitting in his chair, teiching his young man that servit him in his chalmer to spell a, b, ab; e, b, eb. 'better this,' quoth he, 'nor stelling sheipe.'" the sun broke out in great beauty after the shower, glistening on a thousand minute runnels that came streaming down the precipices, and revealing, through the thin vapory haze, the horizontal lines of strata that bar the hill-sides, like courses of ashlar in a building. i failed, however, to detect, amid the general many-pointed glitter by which the blue gauze-like mist was bespangled, the light of the great carbuncle for which the ward hill has long been famous,--that wondrous gem, according to sir walter, "that, though it gleams ruddy as a furnace to them that view it from beneath, ever becomes invisible to him whose daring foot scales the precipices whence it darts its splendor." the hill of hoy is, however, not the only one in the kingdom that, according to tradition, bears a jewel in its forehead. the "great diamond" of the northern sutor was at one time scarce less famous than the carbuncle of the ward hill. "i have been oftener than once interrogated on the western coast of scotland regarding the diamond rock of cromarty; and have been told, by an old campaigner who fought under abercrombie, that he has listened to the familiar story of its diamond amid the sand wastes of egypt." but the diamond has long since disappeared; and we now see only the rock. unlike the carbuncle of hoy, it was never seen by day; though often, says the legend, the benighted boatmen has gazed, from amid the darkness, as he came rowing along the shore, on its clear beacon-like flame, which, streaming from the precipice, threw a fiery strip across the water; and often have the mariners of other countries inquired whether the light which they saw so high among the cliffs, right over their mast, did not proceed from the shrine of some saint or the cell of some hermit. at length an ingenious ship-captain determined on marking its place, brought with him from england a few balls of chalk, and took aim at it in the night-time with one of his great guns. ere he had fired, however, it vanished, as if suddenly withdrawn by some guardian hand; and its place in the rock front has ever since remained as undistinguishable, whether by night or by day, as the scaurs and clefts around it. the marvels of the present time abide examination more patiently. it seems difficult enough to conceive, for instance, that the upper deposit of the lower old red in this locality, out of which the mountains of hoy have been scooped, once overlaid the flag stones of all orkney, and stretched on and away to dunnet head, tarbet ness, and the black isle; and yet such is the story, variously authenticated, to which their nearly horizontal strata, and their abrupt precipices lend their testimony. in no case has this superior deposit of the formation of the coccosteus been known to furnish a single fossil; nor did it yield me on this occasion, among the hills of hoy, what it had denied me everywhere else on every former one. sly search, however, was by no means either very prolonged or very careful. i found i had still several hours of day-light before me; and these i spent, after my return on a rough tumbling sea to stromness, in a second survey of the coast, westwards from the granitic axis of the island, to the bishop's palace, and the ichthyolitic quarry beyond. from this point of view the high terminal hill of hoy, towards the west, presents what is really a striking profile of sir walter scott, sculptured in the rock front by the storms of ages, on so immense a scale, that the colossus of rhodes, pharos and all, would scarce have furnished materials enough to supply it with a nose. there are such asperities in the outline as one might expect in that of a rudely modelled bust, the work of a master, from which, in his fiery haste, he had not detached the superfluous clay; but these interfere in no degree with the fidelity, i had almost said spirit, of the likeness. it seems well, as it must have waited for thousands of years ere it became the portrait it now is, that the human profile, which it preceded so long, and without which it would have lacked the element of individual truth, should have been that of sir walter. amid scenes so heightened in interest by his genius as those of orkney, he is entitled to a monument. to the critical student of the philosophy and history of poetic invention it is not uninstructive to observe how completely the novelist has appropriated and brought within the compass of one fiction, in defiance of all those lower probabilities which the lawyer who pleaded before a jury court would be compelled to respect, almost every interesting scene and object in both the shetland and orkney islands. there was but little intercourse in those days between the two northern archipelagos. it is not yet thirty years since they communicated with each other, chiefly through the port of leith, where their regular traders used to meet monthly; but it was necessary, for purposes of effect, that the dreary sublimities of shetland should be wrought up into the same piece of rich tissue with the imposing antiquities of orkney,--sumburgh head and roost with the ancient cathedral of st. magnus and the earl's palace, and fitful head and the sand-enveloped kirk of st. ringan with the standing stones of stennis and the dwarfie stone of hoy; and so the little jury-court probabilities have been sacrificed without scruple, and that higher truth of character, and that exquisite portraiture of external nature, which give such reality to fiction, and make it sink into the mind more deeply than historic fact, have been substituted instead. but such,--considerably to the annoyance of the lesser critics,--has been ever the practice of the greater poets. the lesser critics are all critics of the jury-court cast; while all the great masters of fiction, with shakspeare at their head, have been asserters of that higher truth which is not letter, but spirit, and contemners of the mere judicial probabilities. and so they have been continually fretting the little men with their extravagances, and they ever will. what were said to be the originals of two of sir walter's characters in the "pirate" were living in the neighborhood of stromness only a few years ago. an old woman who resided immediately over the town, in a little cottage, of which there now remains only the roofless walls, and of whom the sailors, weather-bound in the port, used occasionally to purchase a wind, furnished him with the first conception of his norna of the fitful head; and an eccentric shopkeeper of the place, who to his dying day used to designate the "pirate," with much bitterness, as a "lying book," and its author as a "wicked lying man," is said to have suggested the character of bryce snailsfoot the peddler. to the sorceress sir walter himself refers in one of his notes. "at the village of stromness, on the orkney main island, called pomona, lived," he says, "in , an aged dame called bessie millie, who helped out her subsistence by selling favorable winds to mariners. her dwelling and appearance were not unbecoming her pretensions: her house, which was on the brow of the steep hill on which stromness is founded, was only accessible by a series of dirty and precipitous lanes, and, for exposure, might have been the abode of Æolus himself, in whose commodities the inhabitant dealt. she herself was, as she told us, nearly one hundred years old, withered and dried up like a mummy. a clay-colored kerchief, folded round her head, corresponded in color to her corpse-like complexion. two light-blue eyes that gleamed with a lustre like that of insanity, an utterance of astonishing rapidity, a nose and chin that almost met together, and a ghastly expression of cunning, gave her the effect of hecate. she remembered gow the pirate, who had been a native of these islands, in which he closed his career. such was bessie millie, to whom the mariners paid a sort of tribute, with a feeling betwixt jest and earnest." on the opposite side of stromness, where the arm of the sea, which forms the harbor, is about a quarter of a mile in width, there is, immediately over the shore, a small square patch of ground, apparently a _planticruive_, or garden, surrounded by a tall dry-stone fence. it is all that survives--for the old dwelling-house to which it was attached was pulled down several years ago--of the patrimony of gow the "pirate;" and is not a little interesting, as having formed the central nucleus round which,--like those bits of thread or wire on which the richly saturated fluids of the chemist solidify and crystallize,--the entire fiction of the novelist aggregated and condensed under the influence of forces operative only in minds of genius. a white, tall, old-fashioned house, conspicuous on the hill-side, looks out across the bay towards the square inclosure, which it directly fronts. and it is surely a curious coincidence, that while in one of these two erections, only a few hundred yards apart, one of the heroes of scott saw the light, the other should have proved the scene of the childhood of one of the heroes of byron, "torquil, the nursling of the northern seas." the reader will remember, that in byron's poem of "the island," one of the younger leaders of the mutineers is described as a native of these northern isles. he is drawn by the poet, amid the wild luxuriance of an island of the pacific, as "the blue-eyed northern child, of isles more known to man, but scarce less wild,-- the fair-haired offspring of the orcades, where roars the pentland with his whirling seas,-- rocked in his cradle by the roaring wind, the tempest-born in body and in mind,-- his young eyes, opening on the ocean foam,-- had from that moment deemed the deep his home." judging from what i learned of his real history, which is well known in stromness, i found reason to conclude that he had been a hapless young man, of a kindly, genial nature; and greatly "more sinned against than sinning," in the unfortunate affair of the mutiny with which his name is now associated, and for his presumed share in which, untried and unconvicted, he was cruelly left to perish in chains amid the horrors of a shipwreck. i had the honor of being introduced on the following day to his sister, a lady far advanced in life, but over whose erect form and handsome features the years seemed to have passed lightly, and whom i met at the free church of stromness, to which, at the disruption, she had followed her respected minister. it seemed a fact as curiously compounded as some of those pictures of the last age in which the thin unsubstantialities of allegory mingled with the tangibilities of the real and the material, that the sister of one of byron's heroes should be an attached member of the free church. on my return to the inn, i found in the public room a young german of some one or two and twenty, who, in making the tour of scotland, had extended his journey into orkney. my specimens, which had begun to accumulate in the room, on chimney-piece and window-sill, had attracted his notice, and led us into conversation. he spoke english well, but not fluently,--in the style of one who had been more accustomed to read than to converse in it; and he seemed at least as familiar with two of our great british authors,--shakspeare and sir walter scott,--as most of the better-informed british themselves. it was chiefly the descriptions of sir walter in the "pirate" that had led him into orkney. he had already visited the cathedral of st. magnus and the stones of stennis; and on the morrow he intended visiting the dwarfie stone; though i ventured to suggest that, as a broad sound lay between stromness and hoy, and as the morrow was the sabbath, he might find some difficulty in doing that. his circle of acquirement was, i found, rather literary than scientific. it seemed, however, to be that of a really accomplished young man, greatly better founded in his scholarship than most of our young scotchmen on quitting the national universities; and i felt, as we conversed together, chiefly on english literature and general politics, how much poorer a figure i would have cut in his country than he cut in mine. i found, on coming down from my room next morning to a rather late breakfast, that he had been out among the stromness fishermen, and had returned somewhat chafed. not a single boatman could he find in a populous seaport town that would undertake to carry him to the dwarfie stone on the sabbath,--a fact, to their credit, which it is but simple justice to state. i saw him afterwards in the free church, listening attentively to a thoroughly earnest and excellent discourse, by the disruption minister of the parish, mr. learmonth; and in the course of the evening he dropped in for a short time to the free church sabbath-school, where he took his seat beside one of the teachers, as if curious to ascertain more in detail the character of the instruction which had operated so influentially on the boatmen, and which he had seen telling from the pulpit with such evident effect. what would not his country now give,--now, while drifting loose from all its old moorings, full on the perils of a lee shore,--for the anchor of a faith equally steadfast! he was a lutheran, he told me; but, as is too common in germany, his actual beliefs appeared to be very considerably at variance with his hereditary creed. the creed was a tolerably sound one, but the living belief regarding it seemed to do little more than take cognizance of what he deemed the fact of its death. i had carried with me a letter of introduction to mr. william watt, to whom i have already had occasion to refer as an intelligent geologist; but the letter i had no opportunity of delivering. mr. watt had learned, however, of my being in the neighborhood, and kindly walked into stromness, some six or eight miles, on the morning of monday, to meet with me, bringing me a few of his rarer specimens. one of the number,--a minute ichthyolite, about three inches in length,--i was at first disposed to set down as new, but i have since come to regard it as simply an imperfectly-preserved specimen of a cromarty and morayshire species,--the _glyptolepis microlepidotus_; though its state of keeping is such as to render either conclusion an uncertainty. another of the specimens was that of a fish, still comparatively rare, first figured in the first edition of my little volume on the "old red sandstone," from the earliest found specimen, at a time while it was yet unfurnished with a name, but which has since had a place assigned to it in the genus diplacanthus, as the species longispinus. the scales, when examined by the glass, remind one, from their pectinated character, of shells covering the walls of a grotto,--a peculiarity to which, when showing my specimen to agassiz, while it had yet no duplicate, i directed his attention, and which led him to extemporize for it, on the spot, the generic name ostralepis, or shell-scale. on studying it more leisurely, however, in the process of assigning to it a place in his great work, where the reader may now find it figured (table xiv., fig. ), the naturalist found reason to rank it among the diplacanthi. mr. watt's specimen exhibited the outline of the head more completely than mine; but the orkney ichthyolites rarely present the microscopic minutiæ; and the shell-like aspect of the scales was shown in but one little patch, where they had left their impressions on the stone. his other specimens consisted of single plates of a variety of coccosteus, undistinguishable in their form and proportions from those of the _coccosteus decipiens_, but which exceeded by about one-third the average size of the corresponding parts in that species; and of a rib-like bone, that belonged apparently to what few of the ichthyolites of the lower old red seem to have possessed,--an osseous internal skeleton. this last organism was the only one i saw in orkney with which i had not been previously acquainted, or which i could regard as new, though possibly enough it may have formed part, not of an undiscovered genus, but of the known genus asterolepis, of whose inner framework, judging from the russian specimens at least, portions must have been bony. after parting from mr. watt, i travelled on to kirkwall, which, after a leisurely journey, i reached late in the evening, and on the following morning took the steamer for wick. i brought away with me, if not many rare specimens or many new geological facts, at least a few pleasing recollections of an interesting country and a hospitable people. in the previous chapter i indulged in a brief quotation from mr. david vedder, the sailor-poet of orkney, and i shall make no apology for availing myself in the present, of the vigorous, well-turned stanzas in which he portrays some of those peculiar features by which the land of his nativity may be best recognized and most characteristically remembered. to orkney. land of the whirlpool,--torrent,--foam, where oceans meet in madd'ning shock; the beetling cliff,--the shelving holm,-- the dark insidious rock. land of the bleak, the treeless moor,-- the sterile mountain, sered and riven,-- the shapeless cairn, the ruined tower, scathed by the bolts of heaven,-- the yawning gulf,--the treacherous sand,-- love thee still, my native land. land of the dark, the runic rhyme,-- the mystic ring,--the cavern hoar,-- the scandinavian seer, sublime in legendary lore. land of a thousand sea-kings' graves,-- those tameless spirits of the past, fierce as their subject arctic waves, or hyperborean blast,-- though polar billows round thee foam, i love thee!--thou wert once my home. with glowing heart and island lyre, ah! would some native bard arise to sing, with all a poet's fire, thy stern sublimities,-- the roaring flood,--the rushing stream,-- the promontory wild and bare,-- the pyramid, where sea-birds scream, aloft in middle air,-- the druid temple on the heath, old even beyond tradition's birth. though i have roamed through verdant glades, in cloudless climes, 'neath azure skies, or plucked from beauteous orient meads, flowers of celestial dies,-- though i have laved in limpid streams, that murmur over golden sands, or basked amid the fulgid beams that flame o'er fairer lands, or stretched me in the sparry grot,-- my country! thou wert ne'er forgot. the end. footnotes: [ ] march , . [ ] professor nicol of aberdeen believes the red sandstones of the west highlands are of devonian age, and the quartzite and limestone of lower carboniferous.--_see quarterly journal of the geological society, february ._--w.s. [ ] sir r. murchison considers these rocks silurian. see "quarterly journal" of the geological society, anniversary address. [ ] probably one of the isastrea of edwards. [ ] see a paper by the rev. p.b. brodie, on lias corals, "edinburgh new philosophic journal," april, . [ ] the verses here referred to are introduced into "my schools and schoolmasters," chapter tenth. [ ] for a description of this pond see "my schools and schoolmasters," chapter tenth. [ ] these remarks refer to the poem "on seeing a sun-dial in a churchyard," which was introduced here when these chapters were first published in the "witness," but, having been afterwards inserted in the tenth chapter of "my schools and schoolmasters," is not here reproduced. [ ] mr. peach has discovered fossils in the durness limestone, which rests above the quartzite rock of the west of scotland, that covers the red sandstone long believed to be old red. the fossils are very obscure.--w.s.s. [ ] this second title hears reference to the extent of the author's geologic excursions in scotland, during the nine years from to inclusive. [ ] since the above was written, i have seen an interesting paper in "hogg's weekly instructor," in which the rev. mr. longmuir of aberdeen describes a visit to the lias clay at blackpots. mr. longmuir seems to have given more time to his researches than i found it agreeable, in a very indifferent day to devote to mine; and his list of fossils is considerably longer. their evidence, however, runs in exactly the same tract with that of the shorter list. he had been told at banff that the clay contained "petrified tangles;" and the first organism shown him by the workmen, on his arrival at the deposit, were some of the "tangles" in question. "these" he goes on to say, "we found, as may have already been anticipated, to be pieces of belemnites, well known on the other side of the frith as 'thunderbolts,' and esteemed of sovereign efficacy in the cure of bewitched cattle." though still wide of the mark, there is here an evident descent from the supernatural to the physical, from the superstitious to the true. "satisfied that we had a mass of lias clay before us, we set vigorously to work, in order either to find additional characteristic fossils, or obtain data on which to form a conjecture as to the history of this out-of-the-way deposit; and our labor was not without its reward. we shall now present a brief account of the specimens we picked up. observing a number of stones of different sizes, that had been thrown out, as they were struck, by the workman's shovel, we immediately commenced, and, like an inquisitor of old, knocked our victims on the head, that they might reveal their secrets; or, like a roman haruspex, examined their interior,--not, however, to obtain a knowledge of the future, but only to take a peep into the past. . here, then, we take up, not a regular lias lime nodule, but what appears to have formed part of one; and the first blow has laid open part of a whorl of an ammonite, which, when complete, must have measured three or four inches in diameter, and it is perfectly assimilated to the calcareous matrix. . here is a mass of indurated clay; and a gentle blow has exposed part of two ammonites, smaller than the former, but their shells are white and powdery like chalk. . another fragment is laid open; and there, quite unmistakably, lie the umbo and greater portion of the _plagiostoma concentricum_. . another fragment of a granular gritty structure presents a considerable portion of the interior of one of the shells of a pecten, but whether the attached fragment is part of one of its ears, or of the other valve turned backward, is not so easily determined. . here is a piece of belemnite in limestone, and the fracture in the fossil presents the usual glistening planes of cleavage. . next we take up a piece of distinctly laminated lias, with ammonites as thick as they can lie on the pages of this black book of natural history. . once more we strike, and we have the cast and part of the shell of another bivalve; but the valves have been jerked off each other, and have suffered a severe compound fracture; nevertheless we can have little hesitation in pronouncing it a species of _unio_. . here is another piece of limestone, with its small fragment of another shell, of very delicate texture, with finely marked traverse striæ. we are unwilling to decide on such slight evidence, but feel inclined to refer it to some species of plagiostoma. . here is a piece of pyrites, not quite so large as the first, and so vegetable-like in its markings, that it might be mistaken for part of a branch of a tree. this is also characteristic of the lias; for when the shales are deeply impregnated with bitumen and pyrites, they undergo a slow combustion when heaped up with faggots and set on fire; and in the cliffs of the yorkshire coast, after rainy weather, they sometimes spontaneously ignite, and continue to burn for several months. . as we passed through the works, on our way to the clay, we observed a sort of reservoir, into which the clay, after being freed from its impurities, had been run in a liquid state; the water had evaporated, and the drying clay had cracked in every direction. here we find its counterpart in this large mass of stone; only the clay here, mixed with a portion of lime is petrified, and the fissures filled up with carbonate of lime; thus forming the septaria, or cement stone. we have dressed a specimen of it for our guide, who has a friend that will polish it, when the dark lias will be strikingly contrasted with the white lime, and form rather a pretty piece of natural mosaic. . coming to a simple piece of machinery for removing fragments of shale and stone from the clay, we examined some of the bits so rejected, and found what we had no doubt were fish-scales. . we have yet to notice certain long slender bodies, outwardly brown, but inwardly nearly black, resembling whip-cord in size. are we to regard these as specimens of a fucus, perhaps the _filum_, or allied to it, which is known in some places by the appropriate name of sea-laces? . passing on to the office, we were shown a chop of wood that had been found in the clay, and was destined for the banff museum. it is about eighteen inches in length, and half as much in breadth; and although evidently water-worn, yet we could count between twenty-five and thirty concentric rings on one of its ends, which not only enabled us to form some conjecture of its age previous to its overthrow, but also justified us in referring it to the coniferæ of the _vorwelt_, or ancient world." mr. longmuir makes the following shrewd remarks, in answering the question, "whether have we here a mass of lias clay, as originally deposited, or has it resulted from the breaking up of lias-shale?" "the former alternative," says mr. longmuir, "we have heard, has been maintained; but we are inclined to adopt the latter, and that for the following reasons: . this clay, judging from other localities, is not _in situ_, but has every appearance of having been precipitated into a basin in the gneiss on which it rests, having apparently under it, although it is impossible to say to what extent, a bed of comminuted shells. . the fossils are all fragmentary and water-worn. this is especially the case with regard to the belemnites, the pieces averaging from one to two inches in length, no workman having ever found a complete specimen, such as occurs in the lias-shale at cromarty, in which they may be found nine inches in length. . but perhaps the most satisfactory proof, and one that in itself may be deemed sufficient, is the frequent occurrence of pieces of lias-shale, with their embedded ammonites; which clearly show that the lias had been broken up, tossed about in some violent agitation of the sea, and churned into clay, just as some denudating process of a similar nature swept away the chalk of aberdeenshire, leaving on many of its hills and plains the water-worn flints, with the characteristic fossils of the cretaceous formation." [ ] a description of miss bond and of her "letters" here referred to, is given in the fifth chapter of "my schools and schoolmasters." [ ] the story here referred to is narrated in "scenes and legends of the north of scotland," chap. xxv. [ ] _scaur_, scotice, a precipice of clay. there is no single english word that conveys exactly the same idea. [ ] mr. dick has since disinterred from out the boulder-clays of the burn of freswick, _patella vulgata_, _buccinum undatum_, _fesus antiquus_, _rostellaria_, _pes pelicana_, a _natica_, _lutraria_, and _balanus_. [ ] that similarity of condition in which the hazel and the harder cerealia thrive was noted by our north-country farmers of the old school, long ere it had been recorded by the botanist. hence such remarks, familiarized into proverbs, as "a good _nut_ year's a good _ait_ year;" or, "as the _nut_ fills the _ait_ fills." [ ] for this story, see "scenes and legends of the north of scotland," chap. xxv. [ ] "in the river st. lawrence," says sir charles lyell, "the loose ice accumulates on the shoals during the winter, at which season the water is low. the separate fragments of ice are readily frozen together in a climate where the temperature is sometimes thirty degrees below zero, and boulders become entangled with them; so that in the spring, when the river rises on the melting of the snow, the rocks are floated off, frequently conveying away the boulders to great distances. a single block of granite, fifteen feet long by ten feet both in width and height, and which could not contain less than fifteen hundred cubic feet of stone, was in this way moved down the river several hundred yards, during the late survey in . heavy anchors of ships, lying on the shore, have in like manner been closed in and removed. in october , wooden stakes were driven several feet into the ground, at one point on the banks of the st. lawrence, at high-water mark, and over them were piled many boulders as large as the united force of six men could roll. the year after, all the boulders had disappeared, and others had arrived, and the stakes had been drawn out and carried away by the ice."--'elements,' first edition, p. . [ ] the story of the lady of balconie and her keys is narrated in "scenes and legends of the north of scotland." chap. xi. [ ] this mode is described in a traditionary story regarding a gigantic tribe of _fions_, narrated in "scenes and legends of the north of scotland," chap. iv. [ ] see "my schools and schoolmasters," chap xi. [ ] i can entertain no doubt that the angular groups of palatal teeth figured by agassiz and the russian geologists as those of a supposed placoid termed the ctenodus, are in reality groups of the palatal teeth of dipterus. in some of my specimens the frontal buckler of polyphractus is connected with the gill-covers and scales of dipterus, and bears in its palate what cannot he distinguished from the teeth of ctenodus. the three genera resolve themselves into one. [ ] there is a very admirable remark to this effect in the "travelling memorandums" of the late lord gardenstone, which, as the work has been long out of print, and is now scarce, may be new to many of my readers: "it is certain, and demonstrated by the experience of ages and nations," says his lordship, in referring to the old principalities of france, "that the government of petty princes is less favorable to the security and interests of society than the government of monarchs, who possess great and extensive territories. the race of great monarchs cannot possibly preserve a safe and undisturbed state of government, without many delegations of power and office to men of approved abilities and practical knowledge, who are subject to complaint during their administration, and responsible when it is at an end; or yet without an established system of laws and regulations; so that no inconsiderable degree of security and liberty to the subject is almost inseparable from, and essential to, the subsistence and duration of a great monarchy. but it is easy for petty princes to practise an arbitrary and irregular exercise of power, by which their people are reduced to a condition of miserable slavery. indeed, very few of them, in the course of ages, are capable of conceiving any other means of maintaining the ostentatious state, the luxurious and indolent pride, which they mistake for greatness. i heartily wish that this observation and censure may not, in some instances, be applicable to great landed proprietors in some parts of britain."--travelling memorandums, vol. i. p. . . [ ] the exciting effects of a poor soil, or climate, or of severe usage, on the productive powers of various vegetable species, have been long and often remarked. flavel describes, in one of his ingenious emblems, illustrative of the influence of affliction on the christian, an orchard tree, which had been beaten with sticks and stones, till it presented a sorely stunted and mutilated appearance; but which, while the fairer and more vigorous trees around it were rich in only leaves, was laden with fruit,--a direct consequence, it is shown, of the hard treatment to which it had been subjected. i have heard it told in a northern village, as a curious anecdote, that a large pear tree, which during a vigorous existence of nearly fifty years, had borne scarce a single pear, had, when in a state of decay, and for a few years previous to its death, borne immense crops of from two to three bolls each season. and the skilful gardener not unfrequently avails himself of the principle on which both phenomena seem to have occurred,--that exhibited in the beaten and that in the decaying tree,--in rendering his barren plants fruitful. he has recourse to it even when merely desirous of ascertaining the variety of pear or apple which some thriving sapling, slow in bearing, is yet to produce. selecting some bough which may be conveniently lopped away without destroying the symmetry of the tree, he draws his knife across the bark, and inflicts on it a wound, from which, though death may not ensue for some two or three twelvemonths, it cannot ultimately recover. next spring the wounded branch is found to bear its bunches of blossoms; the blossoms set into fruit; and while in the other portions of the plant all is vigorous and barren as before, the dying part of it, as if sobered by the near prospect of dissolution, is found fulfilling the proper end of its existence. soil and climate, too, exert, it has been often remarked, a similar influence. in the united parishes of kirkmichael and culicuden, in the immediate neighborhood of cromarty, much of the soil is cold and poor, and the exposure ungenial; and "in most parts, where hardwood has been planted," says the rev. mr. sage of resolis, in his "statistical account," "it is stinted in its growth, and bark-bound. comparatively young trees of ash," he shrewdly adds, "_are covered with seed_,--_an almost infallible sign that their natural growth is checked_. the leaves, too, fall off about the beginning of september." valuable literary and scientific works, published by gould and lincoln, washington street, boston. annual of scientific discovery for ; or, year-book of facts in science and art, exhibiting the most important discoveries and improvements in mechanics, useful arts, natural philosophy, chemistry, astronomy, meteorology, zoölogy, botany, mineralogy, geology, geography, antiquities, &c., together with a list of recent scientific publications; a classified list of patents; obituaries of eminent scientific men; an index of important papers in scientific journals, reports, &c. edited by david a. wells, a.m. with a portrait of prof. o.m. mitchell, mo, cloth, $ . . volumes of the same work for years to inclusive. with portraits of professors agassiz, silltman, henry, bache, maury, hitchcock, richard m. hoe, profs. jeffries wyman, and h.d. rogers. nine volumes, mo, cloth, $ . per vol. this work, issued annually, contains all important facts discovered or announced during the year. --> each volume is distinct in itself, and contains _entirely new matter_. influence of the history of science upon intellectual education. by william whewell, d.d., of trinity college, eng., and the alleged author of "plurality of worlds." mo, cloth, cts. the natural history of the human species; its typical forms and primeval distribution. by charles hamilton smith, with an introduction containing an abstract of the views of blumenbach, prichard, bachman, agassiz, and other writers of repute. by samuel kneeland, jr., m.d. with elegant illustrations. mo, cloth, $ . . "the marks of practical good sense, careful observation, and deep research, are displayed in every page. the introductory essay of some seventy or eighty pages forms a valuable addition to the work. it comprises an abstract of the opinions advocated by the most eminent writers on this subject. the statements are made with strict impartiality, and, without a comment, left to the judgment of the reader."--_sartain's magazine._ knowledge is power. a view of the productive forces of modern society, and the results of labor, capital, and skill. by charles knight. with numerous illustrations. american edition. revised, with additions, by david a. wells, editor of the "annual of scientific discovery." mo, cloth, $ . . --> this is emphatically a book _for the people_. it contains an immense amount of important information, which everybody ought to be in possession of; and the volume should be placed in every family, and in every school and public library in the land. the facts and illustrations are drawn from almost every branch of skilful industry, and it is a work which the mechanic and artisan of every description will be sure to read with a relish. important works. a treatise on the comparative anatomy of the animal kingdom. by profs. c. th. von siebold and h. stannius. translated from the german, with notes, additions, &c. by waldo i. burnett, m.d., boston. one elegant octavo volume, cloth, $ . . this is believed to be incomparably the best and most complete work on the subject extant; and its appearance in an english dress, with the additions of the american translator, is everywhere welcomed by men of science in this country. united states exploring expedition; during the years , , , , , under charles wilkes, u.s.n. vol. xii. mollusca and shells. by augustus a. gould, m.d. elegant quarto volume, cloth, $ . . the landing at cape anne; or, the charter of the first permanent colony on the territory of the massachusetts company. now discovered, and first published from the original manuscript, with an inquiry into its authority, and a history of the colony, - , roger conant, governor. by j. wingate thornton. vo, cloth, $ . . --> "a rare contribution to the early history of new england."--_mercantile journal._ lake superior; its physical character, vegetation, and animals. by l. agassiz and others. one volume octavo, elegantly illustrated, cloth, $ . . the hallig; or, the sheepfold in the waters. a tale of humble life on the coast of schleswig. translated from the german of biernatski, by mrs. george p. marsh. with a biographical sketch of the author. mo, cloth, $ . . as a revelation of an entire new phase in human society, this work strongly reminds the reader of miss bremer's tales. in originality and brilliancy of imagination, it is not inferior to those:--its aim is far higher. the cruise of the north star; a narrative of the excursion made by mr. vanderbilt's party in the steam yacht, in her voyage to england, russia, denmark, france, spain, italy, malta, turkey, madeira, &c. by rev. john overton choules, d.d. with elegant illustrations, &c. mo, cloth, gilt backs and sides, $ . ; cloth, gilt, $ . ; turkey, gilt, $ . . pilgrimage to egypt; embracing a diary of explorations on the nile, with observations illustrative of the manners, customs, and institutions of the people, and of the present condition of the antiquities and ruins. by hon. j.v.c. smith, late mayor of the city of boston. with numerous elegant engravings. mo, cloth, $ . . poetical works. complete poetical works of william cowper; with a life and critical notices of his writings. elegant illustrations. mo, cloth, $ . . poetical works of sir walter scott. life and illustrations. mo, cloth, $ . . milton's poetical works. with a life and elegant illustrations. mo, cloth, $ . . --> the above poetical works, by standard authors, are all of uniform size and style, printed on fine paper from clear, distinct type, with new and elegant illustrations, richly bound in full gilt, and plain. works of hugh miller. the old red sandstone; or, new walks in an old field. illustrated with plates and geological sections. new edition, revised and much enlarged, by the addition of new matter and new illustrations, etc. mo, cloth, $ . . this edition contains over _one hundred pages of entirely new matter_, from the pen of hugh miller. it contains, also, several additional new plates and cuts, the old plates re-engraved and improved, and an appendix of new notes. "it is withal one of the most beautiful specimens of english composition to be found, conveying information on a most difficult and profound science, in a style at once novel, pleasing, and elegant."--dr. sprague--_albany spectator._ the footprints of the creator; or, the asterolepsis of stromness, with numerous illustrations. with a memoir of the author, by louis agassiz. mo, cloth, $ . . dr. buckland _said he would give his left hand to possess such power of description as this man._ testimony of the rocks; or, geology in its bearings on the two theologies, natural and revealed. "thou shalt be in league with the stones of the field."--_job._ with numerous elegant illustrations. one volume, royal mo, cloth, $ . . this is the largest and most comprehensive geological work that the distinguished author has yet published. it exhibits the profound learning, the felicitous style, and the scientific perception, which characterize his former works, while it embraces the latest results of geological discovery. but the great charm of the book lies in those passages of glowing eloquence, in which, having spread out his facts, the author proceeds to make deductions from them of the most striking and exciting character. the work is profusely illustrated by engravings executed at paris, in the highest style of french art. the cruise of the betsey; or, a summer ramble among the fossiliferous deposits of the hebrides. with rambles of a geologist; or, ten thousand miles over the fossiliferous deposits of scotland. mo, cloth, $ . . nothing need be said of it save that it possesses the same fascination for the reader that characterizes the author's other works. my schools and schoolmasters; or, the story of my education. an autobiography. with a full-length portrait of the author. mo, cloth, $ . . this is a personal narrative, of a deeply interesting and instructive character, concerning one of the most remarkable men of the age. my first impressions of england and its people. with a fine engraving of the author. mo, cloth, $ . . --> a very instructive book of travels, presenting the most perfectly life-like views of england and its people to be found in any language. --> _the above six volumes are furnished in sets, printed and bound in uniform style_: viz., hugh miller's works, six volumes. elegant embossed cloth, $ . , library sheep, $ . ; half calf, $ . ; antique, $ . . macaulay on scotland. a critique, from the "witness." mo, flexible cloth, cts. gould and lincoln, washington street, boston. would call particular attention to the following valuable works described in their catalogue of publications, viz.: hugh miller's works. bayne's works. walker's works. miall's works. bungener's work. annual of scientific discovery. knight's knowledge is power. krummacher's suffering saviour. banvard's american histories. the aimwell stories. newcomb's works. tweedie's works. chambers's works. harris' works. kitto's cyclopædia of biblical literature. mrs. knight's life of montgomery. kitto's history of palestin. wheewell's work. wayland's works. agassiz's works. [illustration] william's works. guyot's works. thompson's better land. kimball's heaven. valuable works on missions. haven's mental philosophy. buchanan's modern atheism. cruden's condensed concordance. eadie's analytical concordance. the psalmist: a collection of hymns. valuable school books. works for sabbath schools. memoir of amos lawrence. poetical works of milton, cowpar, scott. elegant miniature volumes. arvine's cyolopædia of anecdotes. ripley's notes on gospels, acts, and romans. sprague's european celebrities. marsh's camel and the hallig. roget's thesaurus of english words. hackett's notes on acts. m'whorter's yahveh christ. siebold and stannius's comparative anatomy. marco's geological map, u.s. religious and miscellaneous works. works in the various departments of literature, science and art. * * * * * +-----------------------------------------------------------------+ | transcriber's note: | | | | in this document, _italics_ are represented as underscores, | | =bold text= is marked with equals signs, and bullets are | | represented as » | | | | one of the tables in this document is very wide ( characters) | | | +-----------------------------------------------------------------+ * * * * * an assessment of the consequences and preparations for a catastrophic california earthquake: findings and actions taken prepared by federal emergency management agency from analyses carried out by the national security council ad hoc committee on assessment of consequences and preparations for a major california earthquake [illustration: fema symbol federal emergency management agency] washington, d.c. november table of contents page chapter: i. executive summary of findings, issues, and actions ii. geologic earthquake scenarios iii. assessment of losses for selected potential california earthquakes iv. an assessment of the current state of readiness capability of federal, state, and local governments for earthquake response v. an assessment of the social impacts annex: . copies of correspondence between president carter and governor brown . current california and federal earthquake response planning . california assembly bill no. acknowledgements chapter i executive summary of findings, issues, and actions a. background after viewing the destruction wrought by the eruption of mt. st. helens in washington state in may , president carter became concerned about the impacts of a similar event of low probability but high damage potential, namely a catastrophic earthquake in california, and the state of readiness to cope with the impacts of such an event. as a result of the president's concern, an _ad hoc_ committee of the national security council was formed to conduct a government review of the consequences of, and preparation for such an event. in addition to the federal emergency management agency, the committee included representatives from the office of science and technology policy, the united states geological survey of the department of the interior, the department of defense, the department of transportation, and the national communications system, at the federal level; state of california agencies and california local governments at the state and local levels; and consultants from the private sector. during the summer of , the participants in this review prepared working papers on relevant issues and problem areas for the consideration of the _ad hoc_ committee. pertinent facts, conclusions and recommendations were reviewed with the governor of the state of california. the president reviewed the _ad hoc_ committee's findings and approved the recommendations for federal action. this report summarizes the results of the assessment and notes these actions. a number of federal legislative and administrative actions have been taken to bring about, in the near future, an increased capability to respond to such an event. the earthquake hazards reduction act of (p.l. - ) authorizes a coordinated and structured program to identify earthquake risks and prepare to lessen or mitigate their impacts by a variety of means. the coordination of this program, the national earthquake hazards reduction program (nehrp), is the responsibility of the federal emergency management agency (fema), which is charged with focusing federal efforts to respond to emergencies of all types and lessen their impacts before they occur. the nehrp has six high-priority thrusts: » overall coordination of federal departments and agencies' programs » maintenance of a comprehensive program of research and development for earthquake prediction and hazards mitigation » leadership and support of the federal interagency committee on seismic safety in construction as it develops seismic design and construction standards for use in federal projects » development of response plans and assistance to state and local governments in the preparation of their plans » analysis of the ability of financial institutions to perform their functions after a creditable prediction of an earthquake as well as after an event, together with an exploration of the feasibility of using these institutions to foster hazard reduction » an examination of the appropriate role of insurance in mitigating the impacts of earthquakes. more recently, a cooperative federal, state, local, and private-sector effort was initiated to prepare for responding to a credible large-magnitude earthquake, or its prediction, in southern california. b. summary the review provided the overall assessment that the nation is essentially unprepared for the catastrophic earthquake (with a probability greater than percent) that must be expected in california in the next three decades. while current response plans and preparedness measures may be adequate for moderate earthquakes, federal, state, and local officials agree that preparations are woefully inadequate to cope with the damage and casualties from a catastrophic earthquake, and with the disruptions in communications, social fabric, and governmental structure that may follow. because of the large concentration of population and industry, the impacts of such an earthquake would surpass those of any natural disaster thus far experienced by the nation. indeed, the united states has not suffered any disaster of this magnitude on its own territory since the civil war. the basis for this overall assessment is summarized below and discussed in more detail in the subsequent chapters of this report. c. likelihood of future earthquakes earth scientists unanimously agree on the inevitability of major earthquakes in california. the gradual movement of the pacific plate relative to the north american plate leads to the inexorable concentration of strain along the san andreas and related fault systems. while some of this strain is released by moderate and smaller earthquakes and by slippage without earthquakes, geologic studies indicate that the vast bulk of the strain is released through the occurrence of major earthquakes--that is, earthquakes with richter magnitudes of . and larger and capable of widespread damage in a developed region. along the southern san andreas fault, some miles from los angeles, for example, geologists can demonstrate that at least eight major earthquakes have occurred in the past , years with an average spacing in time of years, plus or minus years. the last such event occurred in . based on these statistics and other geophysical observations, geologists estimate that the probability for the recurrence of a similar earthquake is currently as large as to percent per year and greater than percent in the next years. geologic evidence also indicates other faults capable of generating major earthquakes in other locations near urban centers in california, including san francisco-oakland, the immediate los angeles region, and san diego. seven potential events have been postulated for purposes of this review and are discussed in chapter ii. the current estimated probability for a major earthquake in these other locations is smaller, but significant. the aggregate probability for a catastrophic earthquake in the whole of california in the next three decades is well in excess of percent. d. casualties and property damage casualties and property damage estimates for four of the most likely catastrophic earthquakes in california were prepared to form a basis for emergency preparedness and response. chapter iii gives details on these estimates. deaths and injuries would occur principally because of the failure of man-made structures, particularly older, multistory, and unreinforced brick masonry buildings built before the adoption of earthquake-resistant building codes. experience has shown that some modern multistory buildings--constructed as recently as the late 's but not adequately designed or erected to meet the current understanding of requirements for seismic resistance--are also subject to failure. strong ground shaking, which is the primary cause of damage during earthquakes, often extends over vast areas. for example, in an earthquake similar to that which occurred in , strong ground shaking (above the threshold for causing damage) would extend in a broad strip along the southern san andreas fault, about miles long and miles wide, and include almost all of the los angeles-san bernardino metropolitan area, and all of ventura, santa barbara, san luis obispo, and kern counties. for the most probable catastrophic earthquake--a richter magnitude + earthquake similar to that of , which occurred along the southern san andreas fault--estimates of fatalities range from about , , if the earthquake were to occur at : a.m. when the population is relatively safe at home, to more than , , if the earthquake were to occur at : p.m. on a weekday, when much of the population is either in office buildings or on the streets. injuries serious enough to require hospitalization under normal circumstances are estimated to be about four times as great as fatalities. for the less likely prospect of a richter magnitude . earthquake on the newport-inglewood fault in the immediate los angeles area, fatalities are estimated to be about , to , , at the same respective times. such an earthquake, despite its smaller magnitude, would be more destructive because of its relative proximity to the most heavily developed regions; however, the probability of this event is estimated to be only about . percent per year. smaller magnitude--and consequently less damaging--earthquakes are anticipated with greater frequency on a number of fault systems in california. in either of these earthquakes, casualties could surpass the previous single greatest loss of life in the united states due to a natural disaster, which was about , persons killed when a hurricane and storm surge struck the galveston area of the texas coast in . the highest loss of life due to earthquakes in the united states occurred in san francisco in , when people were killed. by way of comparison (in spite of the vast differences in building design and practices and socioeconomic systems) the devastating tangshan earthquake in china caused fatalities ranging from the official chinese government figure of , to unofficial estimates as high as , . fortunately, building practices in the united states preclude such a massive loss of life. property losses are expected to be higher than in any past earthquake in the united states. for example, san francisco in , and anchorage in , were both much less developed than today when they were hit by earthquakes. and the san fernando earthquake in , was only a moderate shock that struck on the fringe of a large urban area. each of these three earthquakes caused damage estimated at about $ . billion in the then current dollars. estimates of property damage for the most probable catastrophic earthquake on the southern san andreas (richter magnitude +) and for the less probable but more damaging one (richter magnitude . ) on the newport-inglewood fault, are about $ billion and $ billion respectively. by comparison, tropical storm agnes caused the largest economic loss due to a natural disaster in the united states to date but it amounted to only $ . billion (in dollars). it should be noted, however, that substantial uncertainty exists in casualty and property damage estimates because they are based on experience with only moderate earthquakes in the united states (such as the san fernando earthquake) and experience in other countries where buildings are generally less resistant to damage. the uncertainty is so large that the estimated impacts could be off by a factor of two or three, either too high or too low. even if these lowest estimates prevail, however, the assessment about preparedness and the capability to respond to the disasters discussed in this report would be substantially unchanged. assuming a catastrophic earthquake, a variety of secondary problems could also be expected. search and rescue operations--requiring heavy equipment to move debris--would be needed to free people trapped in collapsed buildings. it is likely that injuries, particularly those immediately after the event, could overwhelm medical capabilities, necessitating a system of allocating medical resources to those who could be helped the most. numerous local fires must be expected; nevertheless, a conflagration such as that which followed the tokyo earthquake of , or the san francisco earthquake of , is improbable, unless a "santa ana type" wind pattern is in effect. since the near failure of a dam in the san fernando, california, earthquake of (which was a moderate event), substantial progress has been made in california to reduce the hazard from dams, in some cases through reconstruction. for planning purposes, however, experts believe that the failure of at least one dam should be anticipated during a catastrophic earthquake in either the los angeles or san francisco regions. experience in past earthquakes, particularly the san fernando earthquake, has demonstrated the potential vulnerability of commercial telephone service to earthquakes, including the possibility of damage to switching facilities from ground shaking and rupture of underground cables that cross faults. this is especially serious because immediately following earthquakes, public demand for telephone services increases drastically. this increased demand overloads the capability of the system, even if it had not been damaged, and therefore management action to reduce the availability of service to non-priority users and to accommodate emergency calls is mandatory. radio-based communication systems, particularly those not requiring commercial power, are relatively safe from damage, although some must be anticipated. the redundancy of existing communication systems, including those designed for emergency use, means that some capability for communicating with the affected region from the outside would almost surely exist. restoration of service by the commercial carriers should begin within to hours as a result of maintenance and management actions; however, total restoration of service would take significantly longer. while numerous agencies have the capability for emergency communication within themselves, non-telephonic communication among entities and agencies in the affected area is minimal. this is true for federal, state, and local agencies. this weakness has been pointed out repeatedly by earthquake response exercises, and the problem is raised by almost every emergency preparedness official at every level of government. consequently, a major problem for resolution is the operational integration of communications systems and networks among the relevant federal, state, and local agencies. because of their network-like character, most systems for transportation and water and power generation and distribution, as a whole, are resistant to failure, despite potentially severe local damage. these systems would suffer serious local outages, particularly in the first several days after the event, but would resume service over a few weeks to months. the principal difficulty would be the greatly increased need for these systems in the first few days after the event, when lifesaving activities would be paramount. portions of the san francisco bay area and of the los angeles area contain substantial concentrations of manufacturing capacity for guided missiles and space vehicles, semiconductors, aircraft parts, electronic computing equipment, and airframes. their specific vulnerability to the postulated earthquakes was not analyzed. in the event of major damage, however, the long-term impacts may be mitigated somewhat by such measures as the use of underutilized capacity located elsewhere, substitution of capacity from other industries, imports, use of other products, and drawing-down of inventories. since we have not recently experienced a catastrophic earthquake in the united states, there are many unknowns which must be estimated with best judgment. this is true particularly for the response of individuals as well as governmental and other institutions. popular assumptions of post-disaster behavior include antisocial behavior and the need for martial law, the breakdown of government institutions, and the requirement for the quick assertion of outside leadership and control. practical experience and field studies of disasters, however, indicate that these assumptions are not necessarily correct. on the contrary, the impacts of the disaster commonly produce a sense of solidarity and cooperativeness among the survivors. nonetheless, the perception remains among emergency response officials that there will be an increased need for law enforcement following the event. another major unknown involves whether a medium or short-term warning of the event would be possible and how such a warning could be utilized most effectively. the technology for earthquake prediction is in an early stage of development and, therefore it is problematical that researchers will succeed in issuing a short-term warning before a catastrophic earthquake, should the event occur in the next few years. yet as research progresses, scientifically-based, intermediate-term warnings are possible, but subject to a high degree of uncertainty. consequently, response preparations must be made for both an earthquake without warning, and one with a short-or intermediate-term warning, possibly with a significant level of uncertainty. e. capability for response planning for response to a large-scale disaster is a complicated process encompassing many variables such as population densities and distribution characteristics; land-use patterns and construction techniques; geographical configurations; vulnerability of transportation; communications and other lifeline systems; complex response operations; long-term physical, social, and economic recovery policies. these factors, together with the realization that an earthquake has the potential for being the greatest single-event catastrophe in california, make it incumbent upon the state to maintain as high a level of emergency readiness as is practicable, and to provide guidance and assistance to local jurisdictions desiring to plan and prepare for such events. annex reviews the general nature of preparedness planning and the basic characteristics of california and federal government plans. federal, state, and local emergency response capabilities are judged to be adequate for moderate earthquakes--those that are most likely to occur frequently in california and cause property damage in the range of $ billion. such an event, however, would severely tax existing resources and provide a major test of management relationships among different governmental levels. federal, state, and local officials, however, are quick to point out serious shortcomings in their ability to respond to a catastrophic earthquake. an analysis of the preparedness posture of local governments, california state organizations, and federal agencies, carried out by the california office of emergency services (oes) and fema, indicates that response to such an earthquake would become disorganized and largely ineffective. many governmental units have generalized earthquake response plans, some have tailored earthquake plans, and several plans are regularly exercised. the coordination of these plans among jurisdictions, agencies, and levels of government, however, is inadequate. in addition, the potential for prediction is not incorporated; long-term recovery issues are not considered; and communications problems are significant, as discussed above. overall, federal preparedness is deficient at this time. early reaction to a catastrophic event would likely be characterized by delays, ineffective response, and ineffectively coordinated delivery of support. fema region ix (san francisco) has drafted an earthquake response plan for the san francisco bay area. annex gives an overview of this draft plan. this is a site-specific plan for response to potential catastrophic earthquake occurrences. the emergency response portion relies upon a decentralized approach which provides for federal disaster support activities to be assigned to selected federal agencies by mission assignment letters. no specific plans have been prepared in this detail for other seismic risk areas, although it is expected that the bay area plan could be easily adapted to other areas. the department of defense and the department of transportation are developing detailed earthquake plans that would ensure a well-organized and adequate response to mission assignments for a major earthquake. the plans of other agencies need further development. very significant capabilities to assist in emergency response exist within the california national guard, california highway patrol, the departments of health services and transportation, and the u.s. department of defense. capabilities exist for such lifesaving activities as _aerial reconnaissance, search and rescue, emergency medical services, emergency construction and repair, communications, and emergency housing and food_. current estimates by both federal and state officials, however, indicate that at least to hours would be required before personnel and equipment can be mobilized and begin initial deployment to the affected area. during the period before the arrival of significant outside assistance critical to the saving of lives (especially of those trapped in collapsed buildings), the public would be forced to rely largely upon its own resources for search and rescue, first aid, and general lifesaving actions. the current level of public preparation for this critical phase of response can be described as only minimal. much of the current state of preparedness arises from past programs aimed at a wide spectrum of emergencies, particularly civil defense against nuclear attack. new or strengthened programs are needed to enhance public preparedness. fema has recently entered into a cooperative effort with california state and local governments to prepare an integrated prototype preparedness plan to respond to a catastrophic earthquake in southern california or to a prediction of such an event. the plan's completion, in late , promises to improve substantially the state of readiness to respond to the prediction and the occurrence of an earthquake in that area and to provide a model which could be applied to other earthquake-prone regions of california and the rest of the country. f. findings, issues, and actions the _ad hoc_ committee responsible for this review developed several significant findings related to the implications of major earthquakes in california and our capabilities to respond to them. it then identified major relevant issues raised by these findings and caused a number of actions to be taken. a brief discussion of the results of its review follows. . leadership =finding=: _effective leadership at all governmental levels is the single most important factor needed to improve this nation's preparedness for a catastrophic earthquake in california._ the problem of emergency preparedness is severely complicated because responsibilities for preparation and response cut across normal lines of authority. further complication arises from the large areal extent of the impacts expected from a major earthquake, affecting literally dozens of government entities. the emergency services coordinator at any level of government is effective only to the extent he or she is backed by the political leadership at that level. this is especially true when preparedness activities must be done, for the most part, within existing resources. city and county officials must increasingly accept their share of the responsibility for preparedness, but commitment by state or federal leaders is also essential. the general tendency among elected officials and the public is to ignore the existing hazard problem. experience, however, teaches that effective response mechanisms must be in place before the disaster; they cannot be developed in the time of crisis. overcoming this apathy and developing the organizational arrangements among federal, state, and local government and volunteer agencies--together with the private sector and the general public will require, above all, leadership. =issue=: the leadership role of the federal government in preparing for a catastrophic earthquake in california and how this leadership role is to be exerted require clarification. =action=: the president has communicated with the governor of california to indicate the results of this review, to express concern about the need for cooperative leadership to prepare for the event, and to offer to increase the federal effort with the state of california and local governments in the cooperative undertaking to prepare for a catastrophic earthquake. he stressed that the federal role is to supplement the effort and resources of the state, and that commitment of significant federal resources would be contingent upon the application of significant state resources. in his response to the president's communications, the governor of california underscored the state's readiness to participate in this cooperative effort and announced his signing into law a measure that would provide substantial state resources (see annex ). a summary of the new law (a.b. ) is contained in annex . . management of preparedness and response activities =finding=: _preparedness must be developed as a partnership between federal, state, and local governments with improvements needed at all levels_, as none have the resources or authorities to solve the problem alone. =issue=: since the nation faces a very probable earthquake in california sometime during the next years, fema should provide the necessary leadership, management, and coordination required to strengthen planning and preparedness within the federal government, as delegated under the national earthquake hazards reduction program of and the disaster relief act of . in this effort, fema requires the support and assistance of numerous other federal agencies. =actions=: fema is taking steps to: » strengthen significantly its management, research, application, and coordination functions, as delegated under the national earthquake hazards reduction program and disaster relief act. » lead other agencies in the development of a comprehensive preparedness strategy detailing specific objectives and assignments, and periodically monitor accomplishments in meeting assigned responsibilities. departments and agencies with appropriate capabilities will provide needed support to fema in strengthening federal preparedness and hazard mitigation programs. =issue=: a major deficiency that has been identified is the potential for delay following a catastrophic earthquake in processing a request for a presidential declaration of a major disaster, and the subsequent initiation of full-scale federal support for lifesaving actions. the first few hours are critical in saving the lives of people trapped in collapsed buildings; consequently, this is when federal support is needed most. decisions on post-event recovery aspects of federal assistance can be deferred until lifesaving operations are underway and sufficient information about damage is in hand. =action=: fema will develop and negotiate, before the event, an agreement with the state of california which will enable the president to declare a major disaster and initiate full-scale federal support for lifesaving and humanitarian action within minutes of a catastrophic earthquake. the agreement will defer resolution of issues relating to longer-term restoration and recovery and similar questions with large budgetary implications until adequate damage estimates are available. the executive branch will thus be able to arrive at an informed decision. =issue=: significant improvements in the federal, state, and local capability for coordination of operational response to a catastrophic earthquake are needed. =actions=: fema and other appropriate federal agencies will increase their efforts, in a partnership with appropriate state and local agencies and volunteer and private-sector organizations, to: » complete development and agreement on fully integrated earthquake response plans for both the san francisco and los angeles regions, including provision for predicted as well as unpredicted earthquakes, building upon the existing draft plan for san francisco. » establish a small fema staff in california dedicated to the coordination of earthquake preparedness planning and implementation. » develop improved mechanisms for the coordination of medical and mortuary activities following a catastrophic earthquake. » identify and document the critical requirements for emergency communications--particularly non-telephonic communications--among federal, state, and local agencies. shortfalls between critical requirements and current capabilities, as well as remedial actions or recommended solutions for each will be identified in accordance with the "national plan for communications support in emergencies and major disasters." this review will include consideration of using existing satellite communications or a dedicated system, should it be found necessary. » cooperatively conduct practice response exercises with state and local officials that will prepare officials and the public for conditions that might be encountered in a catastrophic earthquake and that would reveal deficiencies in planning. =issue=: improving the current inadequate preparedness of the public for a catastrophic earthquake requires a substantial increase in public information and public awareness. although public information is primarily a state, local, and private-sector responsibility, the federal government has a role as well. because citizens will have no choice but to rely largely upon their own resources in the first several hours immediately following a catastrophic earthquake, it is important that certain basic knowledge about lifesaving measures be very widely disseminated. =action=: fema will stimulate and work with the state of california and other appropriate groups to develop and publicize earthquake awareness, hazard mitigation techniques, specific post-earthquake actions to be taken, including first aid, and other pertinent information. =issue=: the possibility of a credible, scientifically-based prediction of a catastrophic earthquake poses serious challenges to government and our society. the current level of scientific understanding of earthquake prediction and the available resources are such that present instrumentation efforts are directed toward research rather than maintaining extensive monitoring networks for real-time prediction. the transition from research to fully operational capability will require additional scientific understanding as well as resources. earthquake predictions are possible, perhaps likely, however, from the current research effort. even with a significant level of uncertainty, any scientifically credible prediction that indicates a catastrophic earthquake is expected within about year or less, will require very difficult and consequential decisions on the part of elected officials at all levels of government. decisions may include such possibilities as the mobilization of national guard and u.s. department of defense resources prior to the event, the imposition of special procedures or drills at potentially hazardous facilities, such as nuclear reactors or dams, the condemnation or evacuation of particularly unsafe buildings with the subsequent need for temporary housing, and the provisions of special protection of fragile inventories. if the prediction is correct and appropriate actions are taken, thousands of lives can be saved and significant economic losses can be avoided. the costs of responding to a prediction may be substantial, however, and the commitment of resources undoubtedly will have to be made in the face of considerable uncertainty and even reluctance. indeed, the possibility of an inaccurate prediction must be faced squarely. =actions=: fema, in conjunction with other appropriate federal agencies, state and local governments, and volunteer and private-sector organizations, will increase its actions to develop procedures for responding to a credible, scientific earthquake prediction, including: » identification of constructive and prudent actions to be taken » analysis of the costs and benefits of various alternative actions » identification of roles and responsibilities in deciding which actions should be implemented and by whom » criteria for evaluating circumstances when the provision of federal assistance would be appropriate the u.s. geological survey of the department of the interior will: » maintain a sound and well-balanced program of research in earthquake prediction and hazard assessment based upon a carefully considered strategic plan » work with state and local officials and fema to develop improved mechanisms for the transmission of earthquake predictions and related information, and to plan for the utilization of the capability for earthquake prediction . resources =finding=: while leadership and management are essential ingredients to achieve an adequate earthquake preparedness posture, _the availability of adequate staffing and resources at all levels of government determines the efficacy of agency programs and initiatives_. in many agencies, earthquake preparedness has been accorded a low priority in their programs. this is a manifestation of a more general problem of minimal agency resource allocation to emergency preparedness. the results of the actions that have been indicated will be limited unless additional resources are made available. =issue=: additional resources should be provided as necessary to accelerate the earthquake hazard mitigation and preparedness activities under the national earthquake hazards reduction program. =action=: fema has reassessed its priorities and is allocating resources to increase the staffing, funding, and management attention and direction for earthquake hazards mitigation, including preparations for a catastrophic earthquake in california. this includes an increase of staff resources in fema region ix for federal, state, and local coordination of planning, preparedness, and mitigation. resource needs that cannot be fully met by the reassessment and reallocation for fiscal year should be identified and justified along with needs for fiscal year in the course of the budget submissions for fiscal year . to facilitate an adequate and balanced response by other federal agencies, fema will provide timely guidance to other agencies on specific priorities for this effort in relation to other major preparedness goals. the office of management and budget and the office of science and technology policy will work together to develop a cross-agency ranking of budgetary resources for earthquake preparedness for fiscal year . chapter ii geologic earthquake scenarios a. major events for purposes of assessing the consequences of a major california earthquake, scenarios for seven large earthquakes were developed. the scenarios depict expectable earthquakes that could severely impact on the major population centers of california. in each case they are representative of only one possible magnitude of earthquake that could occur on the indicated fault system. on each fault system there is a greater probability of one or more damaging earthquakes of somewhat smaller magnitude than the postulated event. the postulated earthquakes are listed in the following table. table major california earthquakes ------------------------------------------------------------------------- current annual likelihood probability of of occurrence richter occurrence in next region fault system magnitude[ ] (percent) - years ------------------------------------------------------------------------- los angeles- southern san bernardino san andreas . - high san francisco northern bay area san andreas . moderate san francisco bay area hayward . moderate los angeles newport- moderate inglewood . . -low san diego rose canyon . . low riverside moderate- san bernardino cucamonga . . low los angeles santa monica . . low ------------------------------------------------------------------------- [ ] this is the estimated largest magnitude earthquake expected at a reasonable level of probability. the main shock can be expected to be followed by large aftershocks over a period of weeks or longer. each large aftershock would be capable of producing additional significant damage and hampering disaster assistance operations. ------------------------------------------------------------------------- these earthquake scenarios represent the largest magnitude events estimated on the basis of a variety of geologic assumptions. the appropriateness of these assumptions depends on the intent of the analysis and the state of geologic knowledge. therefore, the resulting estimates may not be appropriate for other purposes, such as the development of seismic design criteria for a specific site. the development of such criteria commonly requires detailed analyses of the site and its immediate geologic environment beyond the scope of this report. consequently, detailed site analyses may require modification of the conclusions reached in this report, particularly fault systems other than the san andreas and hayward faults. b. geologic evidence some of the possible earthquakes listed are repeat occurrences of historical events, others are not, but geologic evidence indicates that earthquakes occurred on these faults before settlement of the region. based on available data, the postulated earthquake magnitudes would be the largest events that could be expected at a reasonable level of probability. they represent a selection of events useful for planning purposes, but are by no means the only such events likely to occur either on these or other fault systems. the historic record of seismicity in california is too short to determine confidently how often large earthquakes reoccur. information on past earthquakes must be gleaned from the geologic record and therefore, presents a picture of past seismicity that is incomplete and not yet fully deciphered. current knowledge about the recurrence of large earthquakes on specific faults is rudimentary. the probabilities of occurrence shown above are order-of-magnitude estimates and subject to considerable uncertainty, especially for the less probable events. c. description of events following are brief descriptions of postulated events. figure gives their geographic location. . los angeles-san bernardino/southern san andreas fault (magnitude . ) for the past several thousand years, great earthquakes have been occurring over a km length of the san andreas fault approximately every to years, years on the average. the last such event took place in . the probability of occurrence of this earthquake is estimated to be currently as large as to percent per year and greater than percent in the next years. the fault skirts the edge of the los angeles-san bernardino metropolitan region, thus most of the urbanized area lies further than miles from the source of strong shaking. because of the distance, shaking would be more hazardous for large structures than for one- to two-story houses. the long duration of shaking could trigger numerous slides on steep slopes and cause liquefaction in isolated areas. . san francisco bay area/northern san andreas fault (magnitude . ) a repeat occurrence of the earthquake, in which the san andreas fault broke over km of its length, would cause severe damage to structures throughout the bay area and adjacent regions. the extensive urban development on lowlands and landfill around san francisco bay would be especially hard hit and liquefaction in many of these areas would intensify the damage to structures erected on them. . san francisco bay area/hayward fault (magnitude . ) the last large events to occur on this fault were in and . should a major earthquake occur, severe ground shaking and liquefaction is expected to cause damage throughout the entire circum-bay area nearly as severe as that resulting from a -type earthquake on the san andreas fault. this earthquake would be of particular concern because of the many dams located along or near the fault. . los angeles/newport-inglewood fault (magnitude . ) this earthquake would be a serious threat to the nearby, densely-populated areas of los angeles. shaking would cause extensive structural damage throughout the los angeles basin and liquefaction near the coast would add still more destruction. . san diego area/rose canyon fault (magnitude . ) this fault--a segment of an active zone of faults extending from the newport-inglewood fault to northern mexico--would present the greatest earthquake risk to the san diego area. severe damage due to shaking and liquefaction could be expected in the coastal areas. because of unstable sea-bed sediments in the offshore area, local tsunamis (tidal waves) are possible. . los angeles/santa monica fault (magnitude . and . ) and riverside/san bernardino/cucamonga fault (magnitude . ) these faults are part of a system of east-west tending faults bordering the northern edge of the los angeles basin. this fault system caused the san fernando earthquake and is geologically similar to the system that generated the large kern county earthquake. although smaller in magnitude than the earthquakes previously described, these postulated events are potentially quite dangerous because of their vicinity to high population densities in southern california. d. earthquake effects detailed maps were prepared for each event showing qualitative estimates of ground shaking intensity resulting from each earthquake. these estimates are indicative of the general severity of damage to ordinary structures. empirical formulae providing quantitative estimates of peak ground motion at various distances from the postulated earthquakes were developed for use in the effects of severe ground shaking on individual structures or critical facilities. no estimates were made of localized effects, such as ground failures related to liquefaction (the complete failure or loss of strength, of a saturated soil due to shaking), landslides, and fault rupture. these effects can be far more destructive than ground shaking alone. [illustration: figure . geographic locations of selected regional events] chapter iii assessment of losses for selected potential california earthquakes a. introduction as part of a program that fema and its predecessor agencies have had underway for a number of years, property loss and casualty estimates were prepared in and for a number of potential maximum credible earthquakes that could impact on the san francisco and the los angeles areas--north san andreas (richter magnitude . ), hayward (richter magnitude . ), south san andreas (richter magnitude . ), and newport-inglewood (richter magnitude . ). these estimates have now been updated as part of the current assessment. estimates of property loss and casualties are based on the expected type and distribution of damage for each postulated earthquake as determined by the size and location of the earthquake and the distribution and character of the buildings and structures within the affected area. methodologies for estimates of this type are approximate at best. consequently, the figures shown below may vary upward or downward by as much as a factor of two or three. this degree of uncertainty does not affect the validity of the conclusions of this report, however, since there are greater uncertainties in all other aspects of emergency response planning. b. property loss estimates the property loss estimates were obtained by first estimating the total replacement dollar value of buildings and their contents, multiplying them by percentage loss factors (inferred from the anticipated strength of shaking in each county), and then summing to obtain the aggregate loss. included in the estimates are private as well as federal, state, and local government buildings, insured and uninsured. excluded from consideration is the replacement value of transportation and communication facilities, dams, utility installations, and special purpose structures (e.g., convention centers and sports arenas). also excluded is the potential damage resulting from a major dam failure or the indirect dollar losses due to such factors as higher unemployment, lower tax revenue, reduced productivity, and stoppage of industrial production. experience indicates that indirect losses could be approximately equal to the dollar amounts lost in buildings and their contents. the property loss estimates for four postulated earthquakes on the faults listed below are as follows. table estimates of property losses for representative earthquakes[ ] -------------------------------------------------------------------------- loss to loss of building contents total loss fault ($ in billions) ($ in billions) ($ in billions) -------------------------------------------------------------------------- northern san andreas hayward newport-inglewood southern san andreas ---------- [ ] uncertain by a possible factor of two to three. -------------------------------------------------------------------------- c. casualty estimates deaths and injuries in these earthquakes principally would occur from failures of man-made structures, particularly older, multistory, and unreinforced brick masonry buildings built before the institution of earthquake-resistant building codes. experience has shown that some modern multistory buildings--constructed as recently as the late 's, but not adequately designed or constructed to meet the current understanding of requirements for seismic resistance--are also subject to failure. consequently, the number of fatalities will be strongly influenced by the number of persons within high-occupancy buildings, capable of collapsing, or by failure of other critical facilities such as dams. additional imponderables are the degree of saturation of the ground at the time of the event and the possibility of weather conditions conducive to the spread of fire. a conflagration such as occurred in the san francisco earthquake, is not considered likely to occur in any of the analyzed events, however, because of improvements in fire resistance of construction and firefighting techniques. nonetheless, numerous smaller fires must be anticipated in any of the analyzed events and a "santa ana type" wind could cause serious problems. an additional element of uncertainty in estimating casualties from earthquake stems from not knowing where most of the population will be at the time of the earthquake. in the early morning (i.e., : a.m.) most people are at home, by far the safest environment during a seismic emergency. at : in the afternoon, on the other hand, the majority of people are at their places of employment and therefore vulnerable to collapse of office buildings. around : p.m. many more people are in the streets and thus subject to injury due to falling debris or failures of transportation systems. consequently, depending on the time of day, wide variations in the number of casualties can be expected. following are estimates of dead and injured (requiring hospitalization) for each of the four representative faults and for the three time periods just discussed. table estimates of casualties[ ] ------------------------------------------------------------------- fault time dead hospitalized[ ] ------------------------------------------------------------------- northern san andreas : a.m. , , : p.m. , , : p.m. , , hayward : a.m. , , : p.m. , , : p.m. , , southern san andreas : a.m. , , : p.m. , , : p.m. , , newport-inglewood : a.m. , , : p.m. , , : p.m. , , ---------- [ ] uncertain by a possible factor of two to three. [ ] injuries not requiring hospitalization are estimated to be from to times the number of deaths. ------------------------------------------------------------------- d. overview of other types of damage for this assessment, estimates of damage to substantial numbers of different type facilities essential to the immediate response capability were updated. earthquakes associated with the same four major fault systems identified earlier in this chapter were used as a basis for these estimates. the types of facilities analyzed included _hospitals_, _medical supply storages_, _blood banks_, and _custodial care homes_, together with their essential services and personnel resources. although newer hospitals in california are being built according to substantially improved seismic safety standards and practices, older hospital facilities can be expected to be poorly resistant to earthquakes. among residential buildings, single family homes are expected to suffer structural damage and loss of contents. damage to multifamily dwellings--particularly older buildings--would, in all likelihood, be more extensive. analysis of expected damage indicates that temporary housing for as many as , families might be needed--a requirement calling for careful planning and exceptional management skills. schools are judged to be among the safest facilities exposed to the earthquakes. since passage of the field act in , after the long beach earthquake, school buildings in california have been continuously improved to withstand seismic hazards. as a result of continuing and substantial upgrading of design and construction practices in the past years, dams and reservoirs can be expected to show an improved performance in an earthquake. nonetheless, on a contingency basis, one dam failure might be assumed for each planning effort. realizing the fact that key communications facilities, earth stations, department of defense voice and data switches, commercial transoceanic cable heads, federal telecommunications system switches, and major direct distance dial switches are located within miles of either los angeles or san francisco, damage must be expected to occur. with this realization, priorities have been assigned to all critical circuits transiting the key facilities, based on established criteria of criticality of service continuity. _national warning systems circuitry, command and control circuits, and circuits supporting diplomatic negotiations_ (of which a high concentration exists in california) are examples of those circuits carrying high-restoration priority. in the civil sector there would be to hours of minimal communications, with a possible blackout of telephonic communications in the area immediately following an earthquake. the commercial carriers would institute network control procedures to regain control of the situation as fast as possible. the impact on transportation facilities in any of the four hypothesized earthquakes could be massive. since the magnitude and severity is unprecedented in recent years, conclusions regarding losses must be accepted as tentative. as in the case of hospitals, however, the lessons learned in earthquakes during the past years are being incorporated in the design and construction of new facilities. in general, all major transportation modes would be affected--_highways_, _streets_, _overpasses and bridges_, _mass transit systems_, _railroads_, _airports_, _pipelines_, and _ocean terminals_, although major variances in losses are expected among the modes. from a purely structural standpoint, the more rigid or elevated systems (such as railroads and pipelines) which cross major faults on an east-west axis would incur the heaviest damage, with initial losses approaching percent. other major systems (such as highways, airports, and pile-supported piers at water terminals) have better survivability characteristics and therefore would fare much better, with damage generally in the moderate range of to percent. these transportation facility loss estimates are stated in terms of immediate post-quake effects. they do not reflect the impact of priority emergency recovery efforts and expedient alternatives that are available, some within hours, to aid in restoration of transportation capacity. in addition, transportation systems generally have an inherently significant degree of redundancy and flexibility. consequently, an unquantified but significant movement capability in all transport modes is expected to survive. finally, these loss estimates do not take into account the question of availability of essential supporting resources, particularly petroleum fuels, electricity, and communications. in the initial response phase, these could prove to be the most limiting factors in the capability of the transportation system. business and industry would be affected by damage to office buildings, plants, and other support facilities. although the san fernando earthquake occurred on the margin of a largely suburban area, industrial facilities incurred significant damage. for example, several buildings of the kind commonly used for light industry or warehouses suffered from collapsed roofs or walls. generally, building codes do not apply to special industrial facilities, and the ability of these structures to resist earthquake shaking will depend largely on the foresight of the design engineer. for example, a major electrical power switching yard and a water filtration plant were seriously damaged in the san fernando earthquake. about percent of the population and industrial resources of the nation are located in california. over percent of these resources (or about . percent of the nation's total) are located in the california counties that are subject to the possibility of damage from a major earthquake. much of the aerospace and electronics industry is centered in california. for example, about percent of the guided missiles and space vehicles, percent of the semiconductors, percent of the electronic computer equipment, and approximately percent of the optical instruments and lenses manufactured in the nation are manufactured in these counties. the probability that all these counties would be affected by one earthquake is extremely remote; yet the significant concentration of key industries remains a concern. for example, about percent of the nation's semiconductors are manufactured in santa clara county, an area along the northern san andres fault that suffered very heavy damage in the san francisco earthquake. estimates of damage to these industrial facilities and the resulting loss of production have not been made. similarly, the resulting impact of possible damage to national production has not been adequately analyzed. federally regulated financial institutions were generically analyzed to determine their ability to continue to promote essential services in the event of a major earthquake like those that have been postulated for this assessment. the conclusion reached thus far is that large-magnitude earthquakes pose no significant or unanticipated problems of solvency and liquidity for such institutions. the federal reserve system and other regulatory entities have procedures in place that are designed--and have been tested--specifically to provide for the continued operation of financial institutions immediately following an earthquake or other emergency. chapter iv an assessment of the current state of readiness capability of federal, state, and local governments for earthquake response a. introduction an earthquake of catastrophic magnitude, with or without credible warning, happens suddenly. the potential for disaster, however, does not occur suddenly. the degree of preparedness and commitment to comprehensive planning and mitigation programs for the inevitable event will largely determine the degree of hardship to be experienced through loss of life, human suffering, property destruction, and the other related economic, social, and psychological aspects of disruption to day-to-day community activities. the impacts can be reduced substantially from current expected levels through the development and implementation of improved and more widely practiced earthquake hazards reduction measures. these include _coordinated emergency preparedness plans and procedures_, _earthquake prediction and warning systems_, _improved construction techniques_, and _effective public education and information programs_. the state of california office of emergency services (oes) and fema conducted an analysis of the readiness capability for potential catastrophic earthquakes in california at the federal, state, and local government levels. the planning of counties and cities, of state agencies, and of federal organizations were reviewed with the following objectives: (a) identify opportunities for improvement; (b) provide a basis for making decisions that would strengthen program direction and planning efforts; and (c) specify resource needs and potential legislative initiatives. annex summarizes current federal and california earthquake planning. the environment in which preparedness planning in california occurs is characterized by the following observations of public expectations and attitudes: » there is widespread public support for government action. » most people have some ideas as to what government should be doing. » there is understanding of the need for hazard reduction as well as emergency response planning. » people are willing, in the abstract, to have government funds spent for hazard mitigation. » the public is not very satisfied with what government officials have done. » public officials perceive that current preparedness plans and response are inadequate at best. as discussed below, the review indicates that all is not well in earthquake plans and preparedness. current plans and preparedness are judged to be adequate for the "moderate" earthquakes most likely to occur frequently in california. by moderate it is meant an event causing property damage on the order of $ to $ billion. such an event, however, will severely tax existing resources and provide a major test of management relationship among different governmental jurisdictions and levels. for a catastrophic earthquake, current plans and preparedness are clearly inadequate, leading to a high likelihood that federal, state, and local response activities would become disorganized and largely fail to perform effectively for an extended period of time. b. state and local response although there are widely differing approaches, local emergency planning in california generally consists of a basic plan and a series of contingency plans. the basic plan establishes the authority, sets forth references, addresses hazard vulnerability, states the planning assumptions, establishes an emergency services organization, assigns tasks, formulates a mutual aid system, and directs the development of specific support annexes. for those hazards identified in the basic plan, a separate contingency plan is then developed to address the unique nature of the hazardous event. the contingency plan contains service support plans for each of the functional operations, including detailed standard operating procedures. the planning efforts of local jurisdictions are coordinated with adjacent jurisdictions and the california oes for consistency. a plan is not considered complete without the support annexes which make the plan operational. the survey undertaken for this assessment disclosed that approximately percent of the jurisdictions examined have existing, basic plans; percent have completed annexes; percent of the basic plans addressed an earthquake hazard vulnerability; percent have planned for earthquake contingency; and only percent (one city) has a plan to respond to an earthquake prediction. at the state level, the california oes, as an integral part of the governor's office, functions as his immediate staff and coordinating organization in carrying out the state's emergency responsibilities. specific emergency assignments have been made to state agencies by the oes director through a series of administrative orders. during emergencies the activities of these agencies and departments are coordinated by the california oes. the state oes is also responsible for maintaining and updating the california emergency plan (cep) and associated readiness plans. as in the case of local plans, the basic document is supported by operational annexes as listed below: contingency mutual aid earthquake fire and rescue earthquake prediction law enforcement oil spill medical nuclear blackmail utilities reactor accident military support radioactive material incident flood supporting systems emergency resources management warning construction and housing emergency broadcast system economic stabilization emergency public information food intelligence operations health radiological defense industrial production manpower petroleum telecommunications transportation utilities based on this planning concept, the review assessed quantitatively the preparedness activities of the state agencies that have preparedness responsibilities in accordance with the cep. the quantitative data are listed in the following table. table quantitative assessment of state preparedness activities ----------------------------------------------------------------- number of percent of preparedness element agencies agencies ----------------------------------------------------------------- existence of plan conduct of exercises public education activities public information activities operational capability ----------------------------------------------------------------- the quality of the plans, activities, and operational capabilities were then evaluated on a scale of (expected to fail/inadequate) to (expected to succeed well/adequate). the qualitative results are shown below. table qualitative assessment of state preparedness activities ---------------------------------------------------------- preparedness element capability rating ---------------------------------------------------------- planning . exercises . public education . public information . operational capability . ---------------------------------------------------------- it should be emphasized that these ratings apply to the state's _present_ level of planning and preparedness for response to a major destructive earthquake (magnitude ), not a moderate (san fernando-type) event. c. federal response at the federal level the principal capability to respond to a catastrophic earthquake in california resides in fema, the agency responsible by law to coordinate federal activities in all emergencies. fema has developed a basic plan for supplemental federal assistance for a major earthquake in the san francisco bay area. this plan, however, covers only the emergency phase of response (first few days of efforts to save lives and protect property). in addition, fema is participating in a broader effort concentrating in southern california. this cooperative effort is getting under way with state and local governments, other federal departments, voluntary agencies, practicing professions, business and commercial interests, labor, educators, and researchers. it is expected to develop an effective program to respond to an earthquake or a credible earthquake prediction in that part of the state. the emphasis is being placed on _public safety, reduction of property damage, self-help on the part of individuals, socioeconomic impacts, improved response and long-range recovery planning, mitigation activities, and public participation for both the post-prediction and immediate post-earthquake periods_. this pilot effort is expected to be usable in other highly seismic areas of california as well as in other states. in the event of a catastrophic earthquake, a substantial number of federal agencies would provide support to and be coordinated by fema. illustrative are the following: . department of defense (dod) initially, local military commanders may provide necessary support to save lives, alleviate suffering, or mitigate property damage. normally, additional dod resources would not be committed until a presidential declaration of an emergency or major disaster. when this occurs, the secretary of the army is dod executive agent for military support. the commander, sixth u.s. army, at the presidio, san francisco, has been further delegated authority to coordinate disaster relief operations in the western portion of the united states. extensive planning and coordination have taken place between the sixth u.s. army and fema region ix. dod emergency functions include: _damage survey_, _search and rescue_, _emergency medical care_, _identification and disposition of dead_, _emergency debris clearance_, _emergency roads and bridge construction_, _airfield repair_, and _identification and demolition of unsafe structures_. specific units have been identified to respond to an earthquake in any of the major population centers of california. for example, at this time the following units would be prepared for commitment within hours after a disaster is declared by the president: » six medical units with a , bed capacity » seven helicopter units with utility helicopters and medium helicopters » one infantry brigade of , personnel » two engineer units with pieces of heavy equipment » two transportation units with cargo trucks and trailers these as well as additional dod assets could be made available, contingent on defense priorities. . the national communication system this agency's plan, the "national plan for communications support in emergencies and major disasters," provides for planning and using national telecommunications assets and resources during presidentially declared emergencies and major disasters. the plan, which has been exercised repeatedly in past disasters, provides the management structure and the communications staff to support fema. restoration priorities have been assigned to all critical circuits. . department of transportation (dot) dot has established an office of emergency transportation. this office has developed and maintains comprehensive emergency plans and procedural manuals for natural disasters and other civil crises. it constantly monitors the civil transportation system for indications of potential adverse impacts from all hazards. it conducts scheduled periodic training and readiness exercises for dot emergency personnel and maintains quick response cells and emergency operating facilities at dot headquarters and in the field to provide an immediate reaction capability. the system has been activated several times in the recent past (e.g., three mile island, energy/fuel crisis, independent truckers' strike, and the mt. st. helens eruption). d. considerations for improving response capability earthquake prediction has not been incorporated into existing plans. response to predictions in the current environment, if given, would be _ad hoc_. the state of california has only a rudimentary plan and the federal government none. the city of los angeles has examined the problem extensively, but only considers its own jurisdiction and has not produced an actionable plan. current planning for the recovery period is incomplete, uncoordinated, and not functional. state and local governments have done little to plan for the recovery period when, following the emergency lifesaving phase, efforts and resources are concentrated on restoring the functioning of the community. they presume that the federal government will "step in" after a presidential declaration. the federal government has an untested draft plan for the san francisco area that is not fully coordinated with the state plans. current federal plans are geared to the provision of assistance on the order of a few hundred million dollars. thus, there is little confidence that they would function under the requirements for tens-of-billions-of-dollars and concomitant service demands. both federal and state agencies need to commit the financial resources and assignment of personnel to maintain and enhance earthquake plans and preparedness. earthquake preparedness, although responding to high damage expectation, is still based upon a relatively low probability occurrence. when it is in competition with pressing social needs for a portion of limited resources, social needs tend to prevail at all levels of government. without a clear commitment, future development of earthquake preparedness, as in the past, is problematic and its implementation is in considerable doubt. the federal earthquake preparedness effort needs to focus on a high state of readiness. history in the area of natural hazard mitigation suggests that assignment of responsibility, even by the president, when not followed by leadership and regular oversight over the allocation of financial resources, seldom leads to programs which can be expected to function. the same weakness is evidenced at the state and local government levels with few exceptions. the stresses likely to occur in emergency response programs after a catastrophic earthquake will be such that effective response will require a cooperative, integrated effort among different jurisdictions and levels of government. experience in other areas of planning and preparedness, particularly for civil defense, indicates that damage to existing programs occurs when the federal government raises expectations of the public and of other levels of government and then fails to follow through with implementation and funding. it is better to maintain the _status quo_ with minor changes at the margin than to announce substantial program initiatives and not meet their requirements. chapter v an assessment of the social impacts often, it is assumed that disasters leave masses of the population in the impacted areas dazed and helpless and unable to cope with the new conditions, or that those not so immobilized panic or display antisocial behavior. another common assumption is that local communities and organizations are rendered ineffective to handle the many problems, leading to further disorganization, loss of morale, and requiring the quick assertion of "strong" outside leadership and control. practical experience and field studies of disasters indicate that these assumptions are not necessarily correct. the widespread sharing of danger, loss, and deprivation produces an intimate cooperativeness among the survivors, which overcomes social isolation and provides a channel for very close communication and expression and a major source of physical and emotional support and reassurance. this capacity seems to account for the resiliency of personality and social organization in dealing with threat and danger. it is also at the base of the ability of social life to regenerate. in addition, a good case can be made in that community systems experiencing impact may be more efficient and rational than they are in "normal" circumstances. normal (pre-disaster) community life traditionally operates at a low level of effectiveness and efficiency. activities are directed toward a very diffuse set of goals, just as human resources within the community are inadequately utilized. upon disaster impact, certain community goals--care for victims and the restoration of essential services--develop a high priority while others are ignored or held in abeyance. thus, the entire range of community resources, even taking into account "losses," can be allocated to the accomplishment of the more critical goals. also, human resources are better utilized. many women, older persons, younger persons, and members of minorities now become "productive;" the "labor" market after impact is open to those underutilized resources. in effect, then, disasters create the conditions for the more efficient utilization of material resources and the more effective mobilization of human resources. to accomplish this, certain modifications have to occur in the normal community structure, since the usual decision-making structures are designed for a different range and type of problem. outsiders see this restructuring process as disorganized, chaotic, and creating the necessity for the imposition of some strong outside authority. on the contrary, this restructuring process is functional and adaptive. its consequences are seen in communities and societies that rebound dramatically from the disruption and destruction to levels of integration, productivity, and growth capacity far beyond the pre-disaster state. in summary, the picture drawn points to the capacity of individuals and institutions to deal with difficult problems created by disaster impact. it also points to the adaptive capacity of social organization within communities to deal with unique and dramatic problems. these findings are not an argument against planning nor against "outside" assistance, but they should condition both the nature of planning and the direction of assistance. annex letters of correspondence the white house washington september , to governor jerry brown as you know, following my trip to view the destructive impacts of the volcanic eruption of mt. st. helens in the state of washington, i directed that an assessment be undertaken of the consequences and state of preparedness for a major earthquake in california. this review, chaired by my science and technology advisor, frank press, is now complete. we are grateful for the assistance provided by your staff and the other state, and local officials in this effort. although current response plans are generally adequate for moderate earthquakes, federal, state, and local officials agree that additional preparation is required to cope with a major earthquake. prudence requires, therefore, that we take steps to improve our preparedness. while the primary responsibility for preparedness rests with the state of california, its local governments and its people, the magnitude of human suffering and loss of life that might occur and the importance of california to the rest of the nation require increased federal attention to this important issue. accordingly, i have directed that the federal government increase its work with you to supplement your efforts. the federal efforts will be led by the federal emergency management agency and include the department of defense and other departments and agencies as appropriate. as a nation, we must reduce the adverse impacts of a catastrophic earthquake to the extent humanly possible by increasing our preparedness for this potential eventuality. sincerely, [signed] jimmy carter the honorable edmund g. brown, jr. governor of california sacramento, california september , the honorable jimmy carter the president the white house washington, d.c. dear mr. president: let me take this opportunity to review our conversations over the last few months regarding increased seismic activity in california. when we met in oakland on july i raised the issue of seismic hazards. i was concerned then with the steady increase in seismic activity in california since . sharing my concern, you directed that the national security council join with my staff and certain local experts to conduct a quick study on the potential for a great earthquake in california. as you know, significant theoretical and public policy research had already been completed by our seismic safety commission, state geologist, earthquake prediction evaluation council and the office of emergency services. together with the u.s. geological survey and the federal emergency management agency (fema), they had clearly been keeping abreast of the state of the art of earthquake prediction. indeed, combined state and federal efforts, founded on major theoretical advances in american, russian and chinese seismic and geological theory since the early s, had shifted the language of earthquake prediction in california from "if" to "when"! in light of my personal interest in this subject, i have signed into law assemblyman frank vicencia's ab , a jointly funded state-federal project to design a comprehensive earthquake prediction-response plan. it is the state's intention to prepare a plan for the greater los angeles area as quickly as feasible. in my view, such a fullscale prediction-response program had become possible only after the research findings of both physical and policy scientists during the past five years. it is my conviction that such a plan is now timely--neither too early nor too late. in this context, your recognition of this issue in our conversation of september in los angeles was a welcome personal reinforcement of our state and local efforts. i am also grateful for the september briefing in sacramento by mr. john macy, director of fema, regarding the latest u.s. geological survey interpretations of anomalies around california's system of geological faults. as soon as we have received the final fema report on the details of those anomalies, i will ask the state geologist to evaluate the report, confer with colleagues in the geological survey and have all state and local officials fully briefed. at that time, i would be grateful for an early opportunity to meet with you and explore next steps. i am confident that a heightened state of awareness among my fellow californians will so deploy the resources of the state, plus available federal supplementary assistance, as to minimize the loss of life and property in the event of a great earthquake. sincerely, /s/ edmund g. brown, jr. governor annex current california and federal earthquake response planning a. nature of emergency planning an emergency, as used in this report, is defined as an unexpected, sudden or out-of-the-ordinary event or series of events adversely affecting lives and property which, because of its magnitude, cannot be handled by normal governmental processes. emergency response planning is the process that addresses preparedness for and response to an emergency. emergency response planning is an evolutionary, ongoing process and is prerequisite to all other emergency readiness activities. it is a comprehensive process that identifies the potential hazardous events, and the vulnerability to such hazards, estimates expected losses, and assesses impacts of such events. the development of written plans is followed by placement of capabilities to implement the response plan and by the conduct of periodic tests and exercises. the most difficult task in the development of an emergency plan is to anticipate as many of the problems and complications resulting from a given disaster situation as possible and to provide a basis for response to those not anticipated. the objective of emergency planning is to create the capacity for government to: » save the maximum number of lives in the event of an emergency » minimize injuries and protect property » preserve the functions of civil government » maintain and support economic and social activities essential for response and the eventual long-term recovery from the disaster emergency planning is a logical and necessary pre-emergency activity for governmental (and other organizational) entities likely to be affected by a disaster's occurrence. to be successful, such planning must be accomplished within the framework of the day-to-day governmental structure and activity but at the same time provide for response to the extraordinary circumstances and requirements inherent in disaster situations. emergency plans include the preparation of guidelines, policy directives, and procedures to be utilized in preparing for and conducting disaster operations, training, and test exercises. they should also contain clear statements of authorities, responsibilities, organizational relationships, and operating procedures necessary for the accomplishment of disaster response and recovery activities. further, they should address the four elements of mitigation, preparedness, response, and recovery (immediate and long-term). once plans are established they must be periodically updated as conditions change. updating may become necessary for a number of reasons: increased scientific, technical, and managerial knowledge; feedback from evaluation of exercises; better understanding of vulnerability; shifts in population and economic activities; construction of new critical facilities; and changes in personnel, organization, and legislation. emergency planning is a shared responsibility at all levels--in this case from the federal through the state and local jurisdictional levels. it should include business, industry, research and scientific institutions, practicing professions, and the individuals. by involving all functions of government, the planning process enhances the capability for implementing the plans through the realistic consideration of available capabilities and elimination of conflicts and inconsistencies of roles and task assignments. further, by being a part of the planning decision-making process and having identified the needs and areas of consideration, individuals, organizations, and officials responsible for emergency operations are better able to relate to the expected impact and the operational environment. the written plans also serve valuable purposes for training and familiarization of new organizations, individuals, and public officials. experience has shown repeatedly that when emergency operations are conducted in accordance with existing plans, reaction time is reduced and coordination improved, with fewer casualties, less property damage, and a higher surviving socioeconomic capability to undertake recovery. other benefits that accrue from planning include the enhancement of hazard awareness. b. california emergency planning response the state of california emergency response planning is a series of related documents, each of which serve a specific purpose. (see figures and .) the basic plan of a jurisdiction (item ( ) in figures and ) is the foundation of this planning process. it is an essential administrative (rather than operational) document, and as such it: » provides the basis (including legal authority) for and the objectives of emergency planning and operations » outlines contingencies (emergency situations) to be planned and prepared for and establishes the general principles and policies (concepts of operations) to be applied to each » describes the emergency organization in terms of who is responsible for what actions » defines interjurisdictional and interservice relationships and the direction and control structure to make assignments and resolve conflicts » contains or refers to information of common interest about supporting facilities, such as the emergency operations center and warning and communications systems » provides the planning basis for other supporting documents which are more operationally oriented the basic plan is supported by a direction and control annex and by functional annexes (see ( ) and ( ) respectively in figures and ). the direction and control annex details how overall responses to an emergency will be managed and coordinated. functional annexes (for both staff and services) are designed to address the extraordinary requirements created by emergencies. they identify the specific needs, the organizational resources available to meet those needs, and the scheme or "concept of operations" for their application. it should be noted that, because of unique requirements, annexes often do not reflect normal departmental structure. an annex becomes a departmental plan only when an agency represents the sole resource for meeting the stated need and when satisfying that need is the only task assigned to that agency by the basic plan. the second major portion of the california state planning structure consists of specific contingency plans (see ( ) in figures and ). one such plan is prepared for each extraordinary emergency or disaster, likely to occur, detailing the probable effects of the emergency on the jurisdiction and the actions to be taken in offsetting these effects. it is also called a "response plan" since it describes the operations to be undertaken to deal with catastrophic situations. contingency plans include service support plans and checklists (see ( ) and ( ) respectively in figures and ). each involved element of the emergency organization details its response actions in service support plans and itemizes functions appropriate to the specific contingency. the contingency plans, service support plans, and related checklists and standard operating procedures constitute the "operational" portions of the overall emergency plan. they address internal procedures to accomplish stated objectives and document, in advance, the specific organizational elements that will respond to each type of disaster or "need," with identification of procedures and resources. the third major part of california's overall state plan is a compendium of information and resources needed to cope with emergencies (see ( ) in figures and ). this includes references describing the control structure (emergency operations center locations, communications, key facilities, personnel lists, and equipment source listings). c. federal earthquake response planning most federal agencies operating within the state have a generic emergency response plan that establishes their internal procedures for responding to disasters. certain agencies such as the corps of engineers and the federal highway administration, which provide services and support that are used on a regular and fairly extensive basis in disaster, tend to have more highly developed disaster response plans. some of them even have rather basic earthquake response segments included in their basic plans. thus, for moderate earthquakes these plans are relatively effective and the federal response can be expected to be at least adequate. few federal agencies, however, have developed any specific plan that is adequate to respond to the demands of a catastrophic event causing property damage exceeding the $ billion range. of federal agencies whose earthquake planning status were recently evaluated by fema region ix, only the sixth u.s. army was determined to have developed a comprehensive capability that is in acceptable detail, has been exercised, and appears to be operationally adequate and reliable. other federal agencies are now beginning to perceive the need to improve their planning and response capability following the expected event, and are gradually responding to this need. providing impetus to this expanded planning activity has been the emergence of the fema region ix earthquake response plan for the san francisco bay area. this is a site-specific fema plan based on a draft that provided for a full range of federal assistance during the emergency lifesaving phase following the earthquake. although this plan never proceeded beyond the draft stage (because of evolving fema disaster field operations policy), it served as the basic guide for the development of the sixth u.s. army plan, and has remained a core document for identifying expected federal agency activities for earthquake recovery in the san francisco bay area. in , the emergency response portion of the fema region ix draft was restructured. the conduct of the post-event response program was shifted from being a centrally directed fema activity under the operational control of the regional director to a decentralized operation which provides for functional disaster support activities to be assigned by the regional director to certain federal agencies by mission assignment letters. table indicates functional task assignment areas. those with the designation "emergency support function (esf)," have been assigned to other federal agencies. table reviews the principal and support agency assignments for each of the esf functions. on the basis of these anticipated mission assignments, the tasked federal agencies participated in the development of operational annexes in the version of the san francisco earthquake response plan. upon completion of the annexes, all agencies were then required to develop the necessary agency support plans and standard operating procedures for accomplishing the mission assignment tasks. additionally, those federal agencies designated in the plan as principal agencies were tasked with the responsibility of organizing and coordinating the activities of federal agencies designated as support. the rationale for this approach was to identify the various functional areas of disaster response for which a federal activity could reasonably be expected to maintain after the occurrence of the event. with the functional areas identified, the range of federal agency talent was evaluated and federal response capabilities matched to expected functional demands. by the development of a matrix (figure ), a total of functional response areas (such as transportation, mass care, and debris removal) were identified, and federal agencies, plus volunteer organizations such as the american national red cross, were designated as having appropriate disaster response capabilities. subsequently, all agencies were rated on their capability for functioning in a principal or a support capacity. these agencies were then provided specific fema region ix mission assignments or tasking statements which, when triggered by a presidential disaster declaration, provide the legal basis for delivering the authorized assistance in response to state and local government needs. the end result of this approach has been to create a much more effective and reliable capability to respond to the needs of an earthquake disaster by those federal agencies from which a significant response would be required. +----------+ |basic plan| . | ( ) | . +----------+ . | | | . | | | . +-----------------+ | | +----------------------------|contingency plans| | | . | ( ) | | | . +-----------------+ | | administrative . operational | | +-------------+ . | | |direction and| . | | |control annex| . | | | ( ) | . | | +-------------+ . | +------+------+ . | | | . | +-------+ +-------+ . +-----------------------+ | staff | |service| . | service support plans | |annexes| |annexes|----------------------| ( ) | | ( ) | | ( ) | . | response checklists | +-------+ +-------+ . | and sop's ( ) | . +-----------------------+ . | . | . | +--------------------+ |resources compendium| | ( ) | +--------------------+ [illustration: =figure : emergency plans (description of and relationship between plan components)=] +-------------------------+ +-------------------------+ | basic plan ( ) | | | | |-+ | |-+ | authorities | | | resources manual(s) | | | policies | |-+ | ( ) | |-+ | responsibilities | | | | | | | | system interfaces | | |-+ | | | |-+ | | | | | | | | | | +-------------------------+ | | |-+ +-------------------------+ | | |-+ |direction and control ( ) | | | | |communication capabilities| | | | +--------------------------+ | | |-+ +--------------------------+ | | |-+ |public safety ( ) | | | | |law enforcement/fire | | | | +---------------------------+ | | | +---------------------------+ | | | |people care ( ) | | | |medical-health/welfare | | | +----------------------------+ | | +----------------------------+ | | |system restoration ( ) | | |engineering/utilities | | +-----------------------------+ | +-----------------------------+ | |resource management ( ) | |transportation, etc. | +------------------------------+ +------------------------------+ +----------------+ +----------------+ | | | | | | | | | earthquake |-+ | flood |-+ | response plan | | | response plan | | | ( ) | | | ( ) | | | | | | | | | | |-+ | | |-+ +----------------+ | | +----------------+ | | | | | | | | | d & c checklist | | | d & c checklist | | +-----------------+ | +-----------------+ | |svcs. sup. | |svcs. sup. | | plans ( ) | | plans ( ) | |checklists & | |checklists & | | sop's ( ) | | sop's ( ) | +-----------------+ +-----------------+ +----------------+ +----------------+ | | | war | | |-+ | |-+ | war | | | | | | response plan | | | response plan | | | ( ) | | | ( ) | | | in-place | | | crisis | | | protection | |-+ | relocation | |-+ +----------------+ | | +----------------+ | | | | | | | | | d & c checklist | | | d & c checklist | | +-----------------+ | +-----------------+ | |svcs. sup. | | svcs. sup. | | plans ( ) | | plans ( ) | |checklists & | | checklists & | | sop's ( ) | | sop's ( ) | +-----------------+ +-----------------+ [illustration: =figure : emergency planning format (a partial illustration of the component parts of a jurisdictional emergency plan)=] table federal emergency management agency region ix earthquake response and assistance tasks (san francisco bay area) annexes to basic plan disaster field activities disaster field location mission assignments emergency transportation (esf- )[ ] communication (esf- ) emergency debris clearance (esf- ) fire fighting (esf- ) emergency roads, airfields, and bridges (esf- ) emergency demolition (esf- ) administrative logistical support (esf- ) emergency medical care (esf- ) search and rescue (esf- ) identification and disposal of dead (esf- ) warnings of risks and hazards (esf- ) emergency distribution of medicine (esf- ) emergency distribution of food (esf- ) emergency distribution of consumable supplies (esf- ) emergency shelter & mass care (esf- ) damage reconnaissance (esf- ) isoseismal analysis authorities referral administration [ ] emergency support functions (esf) are cross-referenced by number in table . table emergency support functions key: a: emergency transportation b: emergency communications c: emergency debris clearance d: fire fighting e: emerg. roads, air fields & bridges f: emergency demolition g: logistical support h: emergency medical care i: search and rescue j: identif. & disposal of dead k: warnings of risks & hazards l: emergency dist. of medicine m: emergency dist. of food n: emergency dist. of consum. supplies o: emerg. shelter, feed, & mass care p: damage reconnaissance +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |esf | | | | | | | | | | | | | | | | | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |annex |(d)|(e)|(f)|(g)|(h)|(i)|(j)|(k)|(l)|(m)|(n)|(o)|(p)|(q)|(r)|(s)| +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ | federal | | | | | | | | | | | | | | | | | | agencies | a | b | c | d | e | f | g | h | i | j | k | l | m | n | o | p | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |dot - faa | s | | | | | | | | s | | | | | | | s | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |dot - fhwa | s | | | | s | | | | | | | | | | | s | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |dot - fra | s | | | | | | | | | | | | | | | s | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |dot - retco- | p | | | | | | | | | | | | | | | | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |dot - umta | s | | | | | | | | | | | | | | | s | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |dot - uscc | s | s | | s | | s | | | s | | | | | | | s | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |dod - th usa | s | s | s | s | s | s | s | p | p | p | | s | s | s | s | p | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |dod - coe | | s | p | s | p | p | | | | | | | | | | | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |icc | s | | | | | | | | | | | | s | s | | | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |da - usfs | | s | | p | s | | | | s | | | | | | s | s | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |da - fns | | | | | | | | | | | | | p | | | | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |doc - marad | s | | | | | s | | s | | | | | | | | | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |ncs | | p | | | | | | | | | | | | | | | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |ayrc | | | | | | | | s | | | | s | | | p | | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |volunteer | | | | | | | | | | | | | | | | | | agencies | | | | | | | | | | | | | | | s | | | (various) | | | | | | | | | | | | | | | | | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |hew | | | | | | | s | | | | | p | | | s | | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |us atty | | | | | | | | | | s | | | | | | | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |dol - osha | | | s | | | | | | | | | | | | | | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |usps | s | | | | | | | | | | | | | | | | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |fbi | | | | | | | | | | s | | | | | | | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |va | | | | | | | | s | | s | | s | s | | s | | +--------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+ |gsa | s | s | | | | s | p | | | | | s | | p | | | +------------------------------------------------------------------------------+ p - principal agencies s - support agencies annex assembly bill no. the governor of california signed into law assembly bill on september , , which, among others, provides for state participation in a joint federal, state, and local program to prepare a comprehensive program for responding to a major earthquake prediction. this action was initiated in january through the actions of the assembly committee on government organization, frank vicencia, chairman. inclusions of specific funds for preparedness was included following a subcommittee on emergency planning and disaster relief hearing on possible earthquake prediction on april , . the text of the law follows: assembly bill no. chapter an act to amend section of, to amend and renumber section of, and to add section . to, the government code, relating to the seismic safety commission, making an appropriation therefor, and declaring the urgency thereof, to take effect immediately. [approved by governor september , . filed with secretary of state september , .] legislative counsel's digest ab , vicencia. seismic safety commission. the seismic safety commission act, which will self-repeal, effective january , , establishes the seismic safety commission, and confers upon it various powers and duties relating to earthquake hazard reduction. the california emergency services act confers various related powers and duties upon the governor, the director and the department of emergency services, and the california emergency council. this bill would amend the seismic safety commission act by: changing the basic subject of the powers and duties of the commission to earthquake hazard mitigation and making certain corresponding changes in its powers and duties; including within commission responsibilities, scheduling on its agenda as required, a report on disaster mitigation issues from the office of emergency services and defining, for such purposes, "disaster" as all natural hazards which could have an impact on public safety; and authorizing the commission to exercise various specified powers in relation to other disasters, as so defined, in connection with issues or items reported or discussed with the office of emergency services at any commission meeting. this bill would also require the commission to initiate, as specified, a comprehensive program to prepare the state for responding to a major earthquake prediction, as specified. this bill would appropriate $ , for the purposes of this act. this act would take effect immediately as an urgency statute. appropriation: yes. _the people of the state of california do enact as follows:_ section . section . is added to the government code, to read: . . the commission shall initiate, with the assistance and participation of other state, federal, and local government agencies, a comprehensive program to prepare the state for responding to a major earthquake prediction. the program should be implemented in order to result in specific tools or products to be used by governments in responding to an earthquake prediction, such as educational materials for citizens. this program may be implemented on a prototypical basis in one area of the state affected by earthquake predictions, provided that it is useful for application in other areas of the state upon its completion. sec. . section of the government code is amended to read: . the commission is responsible for all of the following in connection with earthquake hazard mitigation: (a) setting goals and priorities in the public and private sectors. (b) requesting appropriate state agencies to devise criteria to promote earthquake and disaster safety. (c) scheduling a report on disaster mitigation issues from the office of emergency services, on the commission agenda as required. for the purposes of this subdivision, the term disaster refers to all natural hazards which could have impact on public safety. (d) recommending program changes to state agencies, local agencies, and the private sector where such changes would improve earthquake hazards and reduction. (e) reviewing the recovery and reconstruction efforts after damaging earthquakes. (f) gathering, analyzing, and disseminating information. (g) encouraging research. (h) sponsoring training to help improve the competence of specialized enforcement and other technical personnel. (i) helping to coordinate the earthquake safety activities of government at all levels. (j) establishing and maintaining necessary working relationships with any boards, commissions, departments, and agencies, or other public or private organizations. sec. . section of the government code is amended and renumbered to read: . . to implement the foregoing responsibilities, the commission may do any of the following: (a) review state budgets and review grant proposals, other than those grant proposals submitted by institutions of postsecondary education to the federal government, for earthquake related activities and to advise the governor and legislature thereon. (b) review legislative proposals, related to earthquake safety to advise the governor and legislature concerning such proposals, and to propose needed legislation. (c) recommend the addition, deletion, or changing of state agency standards when, in the commission's view, the existing situation creates undue hazards or when new developments would promote earthquake hazard mitigation, and conduct public hearings as deemed necessary on the subjects. (d) in the conduct of any hearing, investigation, inquiry, or study which is ordered or undertaken in any part of the state, to administer oaths and issue subpoenas for the attendance of witnesses and the production of papers, records, reports, books, maps, accounts, documents, and testimony. (e) in addition, the commission may perform any of the functions contained in subdivisions (a) to (d), inclusive, in relation to other disasters, as defined in subdivision (c) of section , in connection with issues or items reported or discussed with the office of emergency services at any commission meeting. sec. . the sum of seven hundred fifty thousand dollars ($ , ) is hereby appropriated from the general fund to the seismic safety commission for carrying out the provisions of section . of the government code as added by this act, contingent upon receipt of matching federal funds. sec. . this act is an urgency statute necessary for the immediate preservation of the public peace, health, or safety within the meaning of article iv of the constitution and shall go into immediate effect. the facts constituting such necessity are: in order to protect the public safety against earthquakes, including the imminent possibility of major earthquake predictions being made within the next months, it is necessary that this act take effect immediately. acknowledgements =national security council ad hoc committee on assessment of consequences and preparation for a major california earthquake= _dr. frank press_, chairperson, president's science advisor _clifton alexander, jr._, secretary of the army _roderick renick_, department of defense _cecil andres_, secretary of the department of interior _h.w. menard_, department of interior (usgs) _w. bowman cutter_, executive associate director for budget, office of management and budget _lynn daft_, associate director for domestic policy staff, white house _peter hamilton_, special assistant to the secretary of the department of defense _ted hodkowski_, intergovernmental assistant to the president, white house _john w. macy, jr._, director, federal emergency management agency _richard green_, federal emergency management agency _frank camm_, federal emergency management agency _william odom_, military assistant, national security council, white house _robert p. pirie, jr._, assistant secretary for manpower, reserve affairs and logistics, department of defense =working group members= _philip smith_, chairperson, office of science and technology policy _clarence g. collins_, department of transportation _richard diconti_, national communications system _joseph mullinix_, office of management and budget _chris shoemaker_, national security council _charles c. thiel_, federal emergency management agency _stephen travis_, domestic policy staff _robert l. wesson_, office of science and technology policy =selected contributors= _richard e. adams_, state of california, oes region v _james alexander_, state of california, oes region i _william anderson_, national science foundation _ralph archuleta_, united states geological survey _roger d. borcherdt_, united states geological survey _robert d. brown, jr._, united states geological survey _james brown_, george washington university _richard j. buzka_, united states geological survey _maria d. castain_, united states geological survey _lloyd cluff_, woodward-clyde consultants _john crawford_, federal emergency management agency _alex cunningham_, state of california, oes _donna darling_, state of california, oes region ii _gardner davis_, state of california, oes region vi _henry degenkolb_, h.j. degenkolb & associates _joseph domingues_, federal emergency management agency, region ix _russell dynes_, american sociological association _raymond r. eis_, united states geological survey _susan elkins_, federal emergency management agency, region ix _jack f. evernden_, united states geological survey _charles fritz_, national academy of sciences _thomas e. fumal_, united states geological survey _james t. haigwood_, state of california, oes region i _jane victoria hindmarsh_, state of california, oes _connie e. hooper_, federal emergency management agency _william b. joyner_, united states geological survey _harry king_, state of california, oes region ii _henry lagorio_, university of california _richard p. liechti_, united states geological survey _terry meade_, federal emergency management agency, region ix _ugo morelli_, federal emergency management agency _william myers_, federal emergency management agency _robert a. page_, united states geological survey _daniel j. ponti_, united states geological survey _h. roger pulley_, state of california, oes _f. joseph russo_, federal emergency management agency _louis schwalb_, federal emergency management agency _wanda h. seiders_, united states geological survey _paul a. spudich_, united states geological survey _frank steindl_, oklahoma state university _karl steinbrugge_, private consultant _christopher stephens_, united states geological survey _robert stevens_, federal emergency management agency, region ix _john sucich_, federal emergency management agency _hurst sutton_, private consultant _richard traub_, state of california, oes region i _monica l. turner_, united states geological survey _robert e. wallace_, united states geological survey _kay m. walz_, united states geological survey _william w. ward_, state of california, oes region ii _robert r. wilson_, federal emergency management agency _robert p. yerkes_, united states geological survey _mark d. zoback_, united states geological survey * * * * * public domain works from the university of michigan digital libraries) * * * * * +--------------------------------------------------------------+ | transcriber's note: | | | | most of the information in this document is presented in | | wide tables ( characters per line). | | | | a number of obvious typographical errors have been corrected | | in this text. for a complete list, please see the bottom of | | this document. | | | +--------------------------------------------------------------+ * * * * * department of the interior weather bureau manila central observatory catalogue of violent and destructive earthquakes in the philippines with an appendix earthquakes in the marianas islands - by rev. miguel saderra masÓ, s. j. assistant director of the weather bureau manila bureau of printing catalogue of violent and destructive earthquakes in the philippines ( - ). introduction.--the occasion for publishing this catalogue of philippine earthquakes which were of violent and destructive character has been furnished by a request from prof. john milne for a list of such phenomena, to be included in the general earthquake catalogue which this eminent seismologist is preparing under the auspices of the british association for the advancement of science. the said general catalogue has been undertaken with a view toward reducing to uniformity and completing those published years ago by robert mallet ( ) and perrey ( - ). the form adopted for professor milne's new catalogue is very concise, comprising only the date, intensity, and region together with principal localities affected. it will contain only the earthquakes of intensities vii to x according to the scale of de rossi-forel, and these will be divided into three classes: class i will be formed by the earthquakes of sufficient force to produce cracks in buildings and to throw down chimneys; they correspond to force vii of de rossi-forel. class ii consists of the earthquakes which not only threw down chimneys but also walls and some weak structures; force viii of de rossi-forel. class iii comprises the earthquakes which caused general destruction; force ix and x of de rossi-forel. as this classification is as purely conventional as every other and adopted only in the catalogue mentioned, we do not employ it in the present catalogue of philippine earthquakes, but retain the almost universally adopted scale of de rossi-forel. we shall also present more details as to the towns and buildings damaged, the number of victims and other disastrous effects than enter into the catalogue of professor milne. hence, the differences between the list prepared for professor milne as well as the partial catalogue published in our monthly bulletin for february of the present year consist in the following: ( ) this catalogue contains also several earthquakes whose intensities were between vi and vii, while in the former only such figure as according to their effects were decidedly of force vii. ( ) the new catalogue is more complete as to details concerning the towns, etc., which have been destroyed. it is to be regretted that we are unable to present here a complete historical catalogue of all the destruction wrought in the archipelago by earthquakes since the time when legaspi and urdaneta first set foot on these shores. but the old chroniclers, who dwell upon the political happenings with an attention to detail which is occasionally overdone, were invariably laconic when there was question of earthquakes and similar natural phenomena; as a rule they were satisfied with mentioning the occurrence in a general and therefore vague way, without any attempt at precision as to dates and places. still the writers in the philippines did nothing worse than imitate their colleagues throughout the rest of the world. this fact is responsible for the great contrast exhibited by our catalogue as regards the number and details of earthquakes which occurred prior to , records of which have been preserved, and the same data for the period from to the present time. this same difference is observable in all catalogues of a similar nature, even in those which cover phenomena which occurred in europe. as to the philippine writers, an additional excuse is found in the peculiar conditions of life in these islands. as far as we know, only two earthquakes which took place during the period which alone can come under consideration--that is, since the discovery of the archipelago--have claimed a considerable number of victims, and these in the capital, because outside of manila--if we except two or three of the principal cities--the buildings which could become dangerous during an earthquake have always been few. moreover, in a country in which fires consume every year thousands of dwellings and where the terrible typhoons frequently destroy whole towns with heavy loss of lives, the damage done by earthquakes has rarely been so great as to impress those occurrences indelibly upon the memory. this is beyond doubt one of the reasons why prior to the beginning of the nineteenth century hardly any data can be found concerning the numerous earthquakes which during the preceding two centuries must have occurred in the visayas and above all on the large island of mindanao. the first earthquake of which the chronicles contain a mention is that of . there is no reasonable doubt that during the twenty-eight years which had then elapsed since the founding of manila by legaspi, several strong and possibly even destructive earthquakes occurred in this part of luzon island, but, as the author of the "verdadera relación de la grande destrucción * * * del año " tells us, "when first founded, manila consisted of wooden houses roofed with a certain kind of palm leaves, the same which the natives use in their buildings." hence the damage done by these earthquakes must have been insignificant. much more terrible were the losses caused by conflagrations which within a few years twice wiped out the entire city. the first bishop of manila, domingo de salazar, seeing the city exposed to such general destructions by fire like the one of february , , gave the first impulse to the construction of stone buildings and worked indefatigably in this direction. in person he explored the surroundings of manila in quest of stone quarries and by the middle of the year he had nearly finished his palace and the cathedral, when financial difficulties caused a temporary suspension of the work. at the same time a great number of public and private buildings were under construction. the enthusiasm for structures of stone or brick with tile roofs did not diminish during the next fifty years. the chroniclers tell us that "the spaniards began to build their houses of stone and tiles without the so necessary precautions against earthquakes. * * * beautiful structures and dwelling houses were reared, so high and spacious that they resembled palaces; magnificent churches with lofty and graceful towers, within the walls of manila as well as outside of them: all of which made the city very beautiful and gay and contributed equally to health and pleasure." the disaster of , commonly called the earthquake of st. andrew, as it occurred on the feast of this apostle, november , razed nearly every one of these buildings to the ground, and since then the style and appearance of buildings has changed greatly throughout the archipelago, with a correspondingly great saving of lives in the subsequent earthquakes. masonry arches were henceforth banished from the churches; the heavy walls of the latter were further strengthened by massive buttresses; and the towers were given truly enormous substructures. but even with these precautions there is at present hardly one out of the hundreds of churches built during the seventeenth and eighteenth centuries which did not some time or other require important repairs of its masonry work or even partial reconstruction owing to earthquake damages. the only structure of this class which thus far has withstood all convulsions, is the church of st. agustin, manila. nevertheless, as we have stated before, the chroniclers hardly mention all this destruction, except in a very general and cursory manner. i do not hesitate to say: they were accustomed to see similar havoc created nearly every year in one part of the archipelago or the other by some severe typhoon, accompanied by far greater loss of lives and property, and consequently much more felt by the people than the destruction of a church, _convento_, municipal building ("tribunal"), one or two bridges, or other masonry structure. in the present catalogue our aim has been to present all that is known of the various violent and destructive earthquakes on record. the first column of each page contains the ordinal number of the disturbance for purposes of reference. in the second, the date is given as accurately as it could be ascertained, roman numerals being used to designate the months. unfortunately, of some earthquakes only the year is known; of others, the year and month. of one (no. ) the approximate hour has been recorded, but not the day of the month; while of another (no. ) the hour has been preserved for posterity, but whether the phenomenon occurred during february or march, the records leave undecided. in the third column will be found, in the first place, the intensity of the disturbance, roman numerals representing the degrees of the scale of de rossi-forel (i-x); then the region affected most, and finally the damages caused, if known, and other information, if available. in describing the epicentral regions, the present distribution of the archipelago into provinces has been used throughout the catalogue. this division is shown on the first of the two maps of the philippines which accompany this catalogue (plate i). as to the designation "benguet" occasionally occurring in the text where provinces are enumerated, but not found on the map, we beg to offer the excuse that the region thus named is exceedingly well known in the philippines as it contains baguio, _the_ health resort of the islands. for the readers outside of the archipelago we remark that benguet is at present a subprovince of the mountain province, of which it forms the southernmost part. the location of baguio is shown on the map on plate ii. a similar remark applies to lepanto and bontoc, likewise divisions of the mountain province, whose capitals, cervantes and bontoc, are indicated on the same map. as we would hardly be justified in assuming that every reader is in possession of a detailed map of the philippines, and a knowledge of the general distribution and the main directions of the principal mountain systems of an earthquake country is important, we add a second map on which these data are shown by means of dashes, together with the most important seismic regions, and the positions of the principal towns, bays, etc., mentioned in the text. (plate ii.) near the left margin of this second map will be found an index of the seismic regions just mentioned, each of them being represented by its ordinal number (large roman figures). near each of these ordinals is placed the corresponding number of earthquakes since contained in the catalogue (arabic figures), which is followed, in brackets, by an analysis of the said number, in which roman figures designate the degrees of the earthquake, scale of de rossi-forel, while small arabic figures, written like exponents, give the number of earthquakes of each degree of intensity. in drawing the map on plate ii it was not intended to represent the epicentric area of every individual earthquake center (which would have crowded the map beyond reasonable limits), but rather to show the principal seismic regions. hence most of these curves contain more than one focus. the approximate position of each of the latter has, however, been indicated by a star, while the figure placed close to the star gives the number of earthquakes which proceeded from the said center. a word must be said in apology for the constant use in the following list of the spanish word "_convento_." this word which means monastery, cloister, or convent, is universally used in the philippines to designate also the habitation of the clergy attached to a parish church. although these are, as a rule, spacious buildings and were formerly inhabited well-nigh exclusively by friars, they can not properly be called monasteries. wherefore, in order to avoid lengthy circumlocutions, the spanish word "_convento_" has been retained. the reader who is not familiar with this country may find it strange that in reporting earthquake damages so much emphasis appears to be laid on the harm done to churches and _conventos_. this is easily explained by the fact that these buildings were often the only structures within the meizoseismal area, and built nearly everywhere in the most substantial manner. in the present catalogue we have also included, by way of an appendix, the earthquakes which are known to have occurred in the marianas or ladrones group of islands. while their number is too small to warrant separate publication, we believe that the data concerning them will be welcome to the earthquake investigator. catalogue of violent and destructive earthquakes in the philippines. ----+--------------------+-----+------------------------------------------ no. | date. |intensity. | | | epicenter and effects. ----+--------------------+-----+------------------------------------------ | _y. m. d. h. m._ | | | vi | ix |manila and neighboring provinces. damaged | | |many private buildings in manila; cracked | | |the vault of the jesuit church so badly | | |that it had to be demolished and replaced | | |by a ceiling; fissured the walls and | | |ruined the roof of santo domingo church. | | | | i |viii |earthquake of destructive force and long | | |duration in manila; extent of damage | | |unknown. | | | | xi -- -- -- | vi |violent and protracted earthquake. | | | | i -- |viii |manila and adjacent provinces. did | | |considerable damage to some churches and | | |many private houses in manila. its | | |duration was unusually great, it being | | |said that during minutes the shocks were | | |almost continuous. there were several dead | | |and a great number of injured. the | | |repetitions were frequent throughout the | | |year. | | | | xii -- -- | vi-|leyte island. violent chiefly in the | | vii |country around dulag and palo (e coast of | | |northern leyte). it does not appear to | | |have been destructive. | | | | xi -- -- -- | ix |manila and provinces east of it. several | | |writers call it a "terrible earthquake | | |which progressed from e to w." | | | | -- -- -- -- | ix |panay island. great convulsions of the | | |ground; the aclan river changed its | | |course. the few stone buildings in the | | |affected districts, as, for instance, the | | |church at passi, province of iloilo, were | | |badly cracked, the wooden structures | | |either fell, owing to the snapping of the | | |uprights, or remained inclined in various | | |directions. the provinces which suffered | | |most were those of iloilo and capiz. | | | | viii -- -- -- | x |northern luzon. the historians mention it | | |as one of the earthquakes which caused the | | |greatest convulsions in northern luzon, | | |especially in ilocos norte and cagayan, | | |but above all in the region of the central | | |central cordillera, lepanto, and bontoc. | | |the data are somewhat vague. it is said | | |that part of the northern caraballo | | |mountains subsided. | | | | -- -- -- -- | ix |camarines and albay. a destructive | | |earthquake in which, it is said, a | | |mountain burst and emitted a river of | | |water and mud which swept away the town | | |of camarines and others. the name of | | |camarines was at the time used to | | |designate the present town of camalig | | |and the district near the southern slopes | | |of mayon volcano. the flood mentioned | | |was probably an avalanche of water, sand, | | |volcanic ashes, and lapilli, such as also | | |on other occasions have occurred on the | | |slopes of the same volcano during periods | | |of torrential rains. | | | ----+--------------------+-----+------------------------------------------ no. | date. |intensity. | | | epicenter and effects. ----+--------------------+-----+------------------------------------------ | _y. m. d. h. m._ | | | xii -- -- | ix |western mindanao. destructive earthquake. | | |the epicenter appears to have been in | | |illana bay. great landslides are reported | | |to have occurred at point flechas which is | | |between the bays of illana and sibuguey. | | | | i -- -- | x |northern luzon. destructive earthquake, | | |accompanied by great landslides in the | | |mountains and eruptions of water and mud | | |in the region of northern luzon which | | |comprises the provinces of the ilocos, of | | |cagayan, and the cordillera central. all | | |the historians of the archipelago mention | | |this cataclysm which occurred shortly | | |after the almost simultaneous eruptions of | | |sanguir and jolo. | | | | xi -- | x |the most terrible earthquake recorded in | | |the annals of the archipelago. it might | | |almost be said that from manila to cagayan | | |and ilocos norte it left no stone upon the | | |other. in the capital, where during the | | |preceding fifty years a great number of | | |stone buildings had been erected, | | |magnificent churches, palaces, and public | | |buildings, as well as private residences | | |and villas, the destruction was frightful. | | |ten churches were wrecked entirely, to | | |wit: the royal chapel, cathedral, santo | | |domingo, those of the recollects and | | |franciscans, santiago, san antonio, | | |nuestra señora de guia, and the parish | | |churches of binondo and san miguel; only | | |san agustin and the jesuit church remained | | |standing. twelve monasteries, colleges, | | |and hospitals were likewise converted into | | |ruins. no better fared the palace of the | | |governor-general, the real audiencia and | | |up to of the finest residences which, | | |as one author puts it, "in other cities | | |would have been considerable palaces." the | | |rest of the private houses were damaged | | |to so great an extent that the majority | | |had to be demolished. the number of | | |persons killed exceeded and the total | | |of killed and injured is stated to have | | |been , . | | | | | |outside of manila there was a general | | |destruction of villas and other buildings | | |which had been erected on both banks of | | |the pasig river. throughout the | | |neighboring provinces the masonry | | |structures built by the missionaries | | |suffered the same fate as those in manila. | | |from the farthest provinces in the north | | |were reported great alterations of the | | |surface with almost complete disappearance | | |of some native villages, changes in the | | |courses of rivers, subsidences of plains, | | |eruptions of sand, etc. all the writers of | | |the time qualify this disturbance as the | | |most disastrous earthquake not only in | | |luzon, but likewise in mindoro, | | |marinduque, and the other islands south of | | |luzon. on the other hand, the provinces of | | |camarines and albay appear to have | | |suffered little or nothing. | | | | xii -- |viii |the earthquake of november was followed | | |by almost daily repetitions and countless | | |aftershocks, one of which, on december , | | |was of such intensity as to finish the | | |wrecking of many buildings, "leaving [as a | | |chronicler writes] the city in such | | |condition that it was impossible to walk | | |through it." aftershocks of variable force | | |continued to be very frequent throughout | | |an entire year; that is, until the end of | | | . | | | ----+--------------------+-----+------------------------------------------ no. | date. |intensity. | | | epicenter and effects. ----+--------------------+-----+------------------------------------------ | _y. m. d. h. m._ | | | iii -- -- -- | vi |according to several chroniclers, the | | |aforementioned aftershocks were more were | | |more frequent and of greater intensity | | |during the month of march, some of them | | |assuming a violent character. | | | | -- -- -- -- |viii |southern luzon. very violent earthquake, | | |damaging many buildings (von hoff). | | | | v -- -- | vi |earthquake in manila and surrounding | | |provinces. | | | | viii -- | ix |destructive earthquake. some historians | | |maintain that it was as severe as that of | | | ; but it caused fewer ruins, partly on | | |account of its short duration, partly | | |because it found buildings of less height | | |and greater power or resistance than those | | |erected before . nevertheless it | | |destroyed the monastery of santa clara and | | |did great damage to the churches and | | |monasteries of the dominicans and | | |recollects, likewise to the archiepiscopal | | |palace, the jesuit college, and a | | |considerable number of private buildings. | | |the epicentral region appears to have | | |included only the southern part of luzon. | | | | vi -- -- |viii |destructive in manila and adjacent | | |provinces. in the ruins of numerous houses | | | persons perished and many more were | | |injured. of public buildings only the | | |jesuit church is mentioned as having | | |suffered to some extent. | | | | ii -- -- -- |viii |destructive in northern mindoro and | | |batangas province. mention is made of | | |extensive landslides, the opening of many | | |fissures and the subsidence of large | | |tracts on the beach of the northeast | | |coast of mindoro. the repetitions were many | | |and severe. | | | | viii -- -- | vii |damaged some buildings in manila. | | | | ii -- -- -- | vi |several violent earthquakes, which, | | |however, caused no notable damages. | | | | -- -- -- -- | vii |many chroniclers assure us that during | | |this year and the following destructive | | |earthquakes visited manila; but there is | | |great confusion as to the days and months | | |in which they occurred. | | | | ix -- -- | vii |vicinity of taal volcano. violent in | | |manila and the provinces of rizal, laguna, | | |cavite, and batangas. connected with an | | |eruption of the volcano. at each spasm of | | |the latter the earth shook so violently | | |that many buildings in manila and the | | |provinces mentioned suffered much harm, | | |especially those in the vicinity of lake | | |bombon, within which is situated the said | | |volcano. | | | | xi -- -- | ix |remarkable on account of its having been | | |very perceptible throughout the entire | | |archipelago. caused considerable damage in | | |manila and towns in southern luzon. | | | | -- -- -- -- | ix |destructive in the provinces of tayabas | | |and laguna; ruined the church and the | | |church and _convento_ at mauban and other | | |buildings in this and other towns of the | | |two provinces. | | | | -- -- -- -- | ix |destructive in tayabas province, wrecking | | |masonry structures in the town of tayabas | | |and others. | | | ----+--------------------+-----+------------------------------------------ no. | date. |intensity. | | | epicenter and effects. ----+--------------------+-----+------------------------------------------ | _y. m. d. h. m._ | | | viii -- | ix |a violent eruption of taal volcano, which | | |caused great havoc in all the towns on the | | |shores of lake bombon. the shocks which | | |accompanied each of the intermittent | | |outbursts of the volcano were so severe | | |that they left hardly any building | | |undamaged throughout the provinces in the | | |neighborhood of manila--rizal, laguna, | | |cavite, batangas, tayabas, and in northern | | |mindoro. the convulsions of the ground | | |were very remarkable; displacement | | |occurred and fissures, both wide and deep, | | |opened in the entire province of batangas | | |and likewise in cavite province, up to | | |lake bay. as the shocks occurred during | | |many days, the majority of manila's | | |inhabitants abandoned the walled city and | | |lived under tents or in structures of | | |bamboo and nipa. the greatest force of | | |the earthquakes and, consequently, the | | |greatest upheavals seem to have occurred | | |in the region stretching from taal volcano | | |toward talim island (lake bay) and the | | |antipolo mountain range. | | | | | |repetitions and aftershocks were frequent | | |during nearly a year. | | | | v -- | x |another eruption of taal volcano, the most | | |terrible in the history of the islands. | | |all the towns which surrounded lake bombon | | |were destroyed completely. when rebuilt, | | |they were placed at a distance from the | | |lake. there occurred most violent | | |earthquakes which produced disasters in | | |the neighboring provinces equal too, if | | |not exceeding those of . the spasms, | | |separated by intervals of greater or less | | |duration, lasted months, the principal | | |outbursts being always accompanied by very | | |intense earthquakes which made themselves | | |felt throughout a large part of luzon, on | | |mindoro island, and northern panay. | | | | xii | vii |a violent earthquake, but did very slight | | |damage in manila. during the month many | | |more earthquakes of less intensity were | | |felt; in fact they had been frequent ever | | |since the preceding august. there exist no | | |data concerning the provinces around | | |manila. | | | | ii | vii |manila and neighboring provinces. violent | | |earthquake, preceded and followed by | | |numerous shocks of smaller intensity. | | | | xi | vii |very violent. in manila a few walls fell | | |and tile roofs sagged. slight repetitions | | |marked the succeeding days. nothing is | | |known of the happenings in the near-by | | |provinces. | | | | xii -- -- |viii |destructive earthquake. mr. sonnerat | | |states that it wrecked many houses in | | |manila. this traveler was at the time on | | |board a ship in the very bay of manila; | | |hence it is very strange that he does not | | |give the day of the month on which the | | |disaster took place. | | | | ii -- -- |viii |very severe earthquake which laid in ruins | | |several buildings in manila, express | | |mention being made of the church of | | |nuestra señora de guia in ermita, a suburb | | |of manila. this is probably the same | | |disturbance which, according to some | | |writers, in the beginning of february | | |damaged the church of antipolo and others | | |in la laguna and cavite provinces. | | | | iv -- -- | vi |violent earthquake in dapitan and the | | |whole of northwestern mindanao. | | | | v -- |viii |very violent in southern panay, | | |especially in the province of iloilo. | | | ----+--------------------+-----+------------------------------------------ no. | date. |intensity. | | | epicenter and effects. ----+--------------------+-----+------------------------------------------ | _y. m. d. h. m._ | | | vii -- | x |panay island. a terrible earthquake which | | |left the whole island strewn with ruins. | | |of to churches and _conventos_ in | | |iloilo province only two or three remained | | |standing; in the two other provinces, | | |capiz and antique, the destruction was | | |less universal. even the thick walls of | | |the fort at iloilo were breached in many | | |places. there were subsidences in the | | |plains and landslides in the mountains and | | |mighty fissures opened. it is stated that | | |the victims were numerous: in one building | | | persons perished. | | | | -- -- -- -- | ix |many writers assert that during this year | | |a most violent earthquake shook manila | | |and was followed by severe repetitions | | |during the succeeding days. but, | | |although all agree that the quake was | | |destructive, not one of them gives | | |precise information as to its effects. | | | | ii- -- -- | vii |a violent earthquake but not destructive | iii | |in manila took place between february | | |and march . it fissured walls and ruined | | |tile roofs. | | | | x -- -- | ix |destructive earthquake in camarines | | |province. it wrecked many churches, | | |_conventos_, and other buildings | | |throughout the province, from san miguel | | |bay to the vicinity of albay. | | | | ii -- -- | vii |albay. violent earthquakes which preceded | | |and accompanied the great eruption of | | |mayon volcano, province of albay. several | | |towns situated on the slopes of the | | |mountain were destroyed by this outburst, | | |while others, at a greater distance, | | |suffered less severely. | | | | -- -- -- -- | vii |dapitan, northwestern mindanao. several | | |violent earthquakes with countless | | |repetitions distributed through months. | | | | i -- -- -- | vii |earthquake, violent in manila and | | |destructive in cagayan and isabela | | |provinces, northeastern luzon. | | | | ix -- -- | ix |central luzon. destructive, making many | | |ruins throughout the provinces of tayabas, | | |laguna, rizal, and nueva ecija. the | | |churches of cavinti and lukban were | | |destroyed, that of antipolo and others | | |badly damaged. | | | | x -- -- | ix |destructive in manila and neighboring | | |provinces. spoiled the bridge of spain | | |and the barracks in its vicinity, the | | |church of saint francis and others and | | |many private houses. frightened by the | | |continual repetitions, people left the | | |city to live in nipa houses and under | | |tents. the undulations seemed to come | | |from north-northwest. | | | | xi |viii |destructive earthquake. damaged several | | |churches in manila, likewise the prison | | |and many private residences. the shocks | | |appeared to advance from south to north. | | | | i -- | ix |southern luzon. destructive in the | | |provinces of rizal, laguna, and tayabas. | | |in manila the damage was confined to the | | |cracking of walls and the falling of such | | |as had little power of resistance; but | | |toward laguna and tayabas the destruction | | |was greater; the complete destruction of | | |the church and _convento_ of mauban is | | |expressly mentioned. | | | ----+--------------------+-----+------------------------------------------ no. | date. |intensity. | | | epicenter and effects. ----+--------------------+-----+------------------------------------------ | _y. m. d. h. m._ | | | i -- -- | vii |very violent earthquake in western | | |mindanao. the epicenter was in illana | | |bay. severe shocks were felt in cotabato | | |and zamboanga, kilometers distant | | |from each other. | | | | -- -- -- -- | ix |destructive earthquake in sorsogon and | | |masbate. ruined the masonry buildings. in | | |sorsogon bay extensive subsidences | | |occurred; the sea invaded the town, | | |causing great destruction and claiming | | |many victims. | | | | ix | ix |central luzon. destructive earthquake | | |which made itself felt with violence in | | |the provinces of rizal, laguna, cavite, | | |batangas, tayabas, bataan, zambales, | | |pampanga, bulacan, and nueva ecija. in | | |manila it damaged severely a great number | | |of buildings, among them the cathedral and | | |the churches of the jesuits, san miguel, | | |and paco, the church and _convento_ at | | |pandacan (near manila), and many houses. | | |it is stated that the damage was | | |(relatively) vastly greater in the | | |provinces of bataan, cavite, and batangas, | | |where many fissures opened and subsidences | | |and landslides occurred. the zone most | | |severely chastised seems to have stretched | | |from the zambales mountain range as far as | | |the coasts of batangas and northern | | |mindoro. aftershocks were frequent until | | |the middle of october. | | | | ix -- -- | vi |very strong earthquake in camarines and | | |albay provinces. | | | | xii -- -- | ix |destructive earthquake in batangas | | |province and northern mindoro. ruined | | |many buildings, among which were the | | |church of taal and the church and | | |_convento_ of bauang; the church of | | |batangas likewise suffered severely. | | | | -- -- -- -- |viii |destructive earthquake in camarines | | |province. made ruins in many towns of the | | |southeastern part of the province, express | | |mention being made of the church, | | |_convento_, tribunal, and the schools of | | |pulangui. | | | | iii -- -- |viii |very violent earthquake in southeastern | | |luzon. caused likewise some ruins in the | | |provinces of camarines, albay, and | | |sorsogon. | | | | -- -- -- -- | vi |very strong earthquakes throughout the | | |district of cotabato and the south of | | |lanao district; but it is not known | | |whether they caused extensive damages. | | | | iii | vii |violent earthquake; cracked some buildings | | |in manila and the neighboring provinces. | | | | vii | vii |violent earthquake which displayed its | | |greatest intensity to the east-northeast | | |of manila, in the vicinity of casiguran | | |and baler bays. damaged the church and | | |_convento_ of baler. several aftershocks | | |followed during the next days. | | | | ix -- |viii |ilocos norte and cagayan. the epicenter | | |lay within the central cordillera. did | | |some damage to the church of piddig and to | | |other towns situated near the cordillera. | | | | x | vi |laguna province. very strong earthquake, | | |doing slight damage in the towns south of | | |lake bay and close to the volcanic cone of | | |mount maquiling. | | | ----+--------------------+-----+------------------------------------------ no. | date. |intensity. | | | epicenter and effects. ----+--------------------+-----+------------------------------------------ | _y. m. d. h. m._ | | | vi | x |manila and adjacent provinces. a | | |disastrous earthquake, comparable with | | |that of . laid in ruins the cathedral | | |and nearly all the other churches, except | | |san agustin, the palace of the | | |governor-general, the audiencia, the | | |barracks, warehouses, etc.; all in all, | | |public buildings in ruins and others | | |badly damaged. of private houses were | | |destroyed, left tottering. total, | | | , buildings in ruins or badly damaged. | | |the number of victims was appalling. it is | | |estimated that in manila and the | | |surrounding towns alone the number of | | |killed reached , that of the injured | | | , . the catastrophe likewise involved | | |many towns in rizal, laguna, and cavite, | | |where it destroyed churches and a great | | |number of houses. | | | | vi -- -- | vii |violent earthquake which in manila and | | |neighboring towns brought to the ground | | |several buildings left in a tottering | | |condition by the preceding disturbance. | | | | i -- -- | vi |origin, south of illana bay. it was felt | | |very strongly both at zamboanga and | | |cotabato; the former west, the latter | | |east of the bay mentioned. | | | | xi -- | vi |strong earthquake which caused great | | |excitement in manila and adjacent | | |provinces. | | | | xii -- | vii |ilocos norte. very violent earthquake. | | |damaged several buildings at laoag and in | | |other towns of the province. | | | | i | vi |albay province. very strong earthquake. | | | | iii -- | vi |ilocos norte. very strong earthquake. | | |shocks of varying intensity were frequent | | |in this province during the months | | |december, , to april, . | | | | xii | vi |samar island. very strong and prolonged | | |earthquake. | | | | iv -- -- | vi |leyte island. very strong earthquake. | | | | vi | vi |panay island. very strong earthquake in | | |iloilo and other towns of the southern | | |part of the island. frequent, but weak | | |shocks had been felt since june . | | | | viii -- | ix |masbate island. disastrous earthquake. | | |destroyed the few masonry buildings extant | | |on the island and ruined or inclined | | |hundreds of houses of wood or light | | |materials; large trees fell, fissures | | |opened, and vast landslides occurred in | | |the mountains and along the coasts, | | |especially in the south of the island. | | |countless repetitions followed, over | | |of the more severe ones having been | | |counted during the first fortnight after | | |the earthquake. | | | | x |viii |neighboring provinces east and south of | | |manila, and northern mindoro. on luzon the | | |provinces chiefly affected were rizal, | | |laguna, cavite, and batangas. in manila | | |this earthquake did considerable damage to | | |quite a number of buildings. in the | | |provinces of cavite and batangas a few | | |churches and _conventos_ were wrecked. | | |there was no loss of life. repetitions | | |were frequent during the days | | |immediately following the earthquake. | | | ----+--------------------+-----+------------------------------------------ no. | date. |intensity. | | | epicenter and effects. ----+--------------------+-----+------------------------------------------ | _y. m. d. h. m._ | | | x | vii |very violent earthquake in southern | | |luzon, especially in laguna province. | | |slightly damaged some buildings. | | | | iii -- | vi |northeastern samar. very strong | | |earthquake. | | | | v | vii |northern luzon. very violent earthquake | | |in the provinces of ilocos norte, | | |cagayan, isabela, and the northern part | | |of the mountain province. | | | | xi -- | vii |central mindanao. a violent earthquake | | |whose epicenter lay between the gulf of | | |davao and the province of misamis. during | | |the months of november and december | | |occurred many repetitions, some of them | | |very intense. | | | | ii -- | ix |camiguin island. destructive earthquake | | |which affected only the extreme north of | | |the island, where subsequently, on the | | | th of april, a volcano which had been | | |believed extinct, burst forth again near | | |its base. this great earthquake was the | | |first of a series of shocks which preceded | | |the eruption. it ruined many buildings | | |constructed of wood, and rent asunder the | | |massive walls of the churches at mambajao | | |and catarman, while in the mountains it | | |caused many landslides. between february | | | and april , the date of the volcanic | | |eruption, four violent earthquakes were | | |felt on camiguin and the neighboring | | |islands of mindanao, cebu, bohol, etc., | | |aside from countless shocks of less | | |intensity. with the eruption, the | | |earthquakes ceased completely. | | | | vi | vi |district of davao, southeastern mindanao. | | |violent earthquake throughout the region | | |surrounding davao gulf, with frequent | | |aftershocks during the ensuing days. | | | | vii | vi |very strong earthquake, remarkable for its | | |wide extension, as it was felt strongly in | | |all the provinces of luzon north of the | | |sixteenth parallel of north latitude. | | |repetitions were frequent for three or | | |four days. | | | | x | vii |district of davao, southeastern mindanao. | | |a very violent earthquake, shaking the | | |region around the gulf of davao. | | | | xi -- | vii |surigao, northeastern mindanao. very | | |violent and prolonged earthquake in the | | |province of surigao; also remarkable for | | |its extension, being felt intensely | | |throughout eastern mindanao and | | |perceptible on all the visayan islands. | | | | xi | vii |very violent earthquake in western | | |mindanao and on the islands of basilan | | |and jolo. it caused slight damage to | | |several buildings at zamboanga. | | | | xii | ix |destructive earthquake throughout the | | |districts of lanao, cotabato, and davao, | | |mindanao. it is reported that at cotabato | | |and pollok not a single building remained | | |standing; the happenings in the moro | | |villages and forts are not known. even in | | |davao, at a distance of kilometers, | | |it developed great violence. within one | | |hour three series of most violent shocks | | |were experienced, accompanied by | | |subterraneous rumblings. | | | ----+--------------------+-----+------------------------------------------ no. | date. |intensity. | | | epicenter and effects. ----+--------------------+-----+------------------------------------------ | _y. m. d. h. m._ | | | xii |viii |most violent earthquake in the same | | |regions of lanao and cotabato, which | | |completed the devastation of the | | |preceding. also in this earthquake several | | |separate groups of shocks could be | | |distinguished, which occurred within the | | |space of a little more than half an hour. | | |the subterranean noises were much stronger | | |than on the preceding day and caused | | |consternation. during the first few days | | |following these quakes occurred uncounted | | |repetitions, some of which, like the | | |principal earthquakes, were perceptible | | |not only throughout mindanao, but likewise | | |in the visayas up to distances exceeding | | | kilometers. | | | | xii | vii |very violent earthquake throughout the | | |length of eastern mindanao, from surigao | | |to davao. it was likewise very perceptible | | |on samar and leyte islands. for a number | | |of days there were many repetitions, some | | |of them very intense, notably those which | | |took place on the st and d. | | | | i | vii |violent earthquake close to the coast of | | |zambales, near the town of agno. the | | |shock was repeated ten to twelve times, | | |accompanied by subterraneous noises; an | | |extraordinary wave was seen in the sea | | |close to the coast and in the agno river | | |which empties into the sea near the town. | | |the affected area was very small, which | | |makes it appear probable that the cause | | |must be sought in some displacements in | | |the scarps of the coast. | | | | i | vi |very strong earthquake in the province of | | |ilocos norte, followed by numerous | | |repetitions of considerable intensity | | |during the th, th, and th. | | | | vii | vi |camarines and albay. very strong | | |earthquake, followed by frequent | | |repetitions during the next two days. | | | | viii -- | vi |district of davao, southeastern mindanao. | | |very strong and prolonged earthquake in | | |the vicinity of mount apo; repetitions | | |somewhat frequent during several days. | | | | ix -- | vi |violent earthquake in northern samar, | | |catanduanes island, and the provinces of | | |sorsogon and albay, having its origin | | |to the northeast of san bernardino strait. | | |on the same and the following day occurred | | |four repetitions of moderate intensity. | | | | ix | vi |very strong earthquake in the northern | | |part of the mountain province, luzon, | | |which, during the month, was preceded and | | |followed by other shocks of less | | |intensity. | | | | xii |viii |most violent earthquake in the region | | |southwest of manila, which is comprised | | |between the zambales mountain range and | | |the northern part of mindoro. it did | | |considerable damage to buildings in the | | |provinces of bataan, cavite, and batangas. | | |the towns which suffered most severely | | |were balanga, tuy, nasugbu, calaca, | | |balayan, taal, and batangas. several | | |shocks of small intensity preceded the | | |principal quake between and o'clock. | | | | i | vi |an earthquake which was very strong in | | |batangas province and strong in northern | | |mindoro and the provinces of tayabas, | | |cavite, laguna, rizal, and bulacan. | | |during the preceding days several light | | |shocks had been felt. | | | ----+--------------------+-----+------------------------------------------ no. | date. |intensity. | | | epicenter and effects. ----+--------------------+-----+------------------------------------------ | _y. m. d. h. m._ | | | iii -- |viii |southern samar. destructive earthquake | | |whose meizoseismic area included only the | | |town of mercedes--where some walls were | | |thrown down and others cracked--and a few | | |unimportant villages in the vicinity, | | |situated on the pacific coast, near which | | |was the seat of disturbance. | | | | iii | vii |northern luzon. this earthquake was | | |violent in ilocos norte, ilocos sur, and | | |the mountain province. it was remarkable | | |for its duration of nearly one minute. | | |the resulting damage was negligible. | | | | vi | vi |this earthquake was violent in | | |northeastern mindoro and very strong on | | |romblon and marinduque islands, likewise | | |in the province of batangas. during june, | | |july, and august the same region | | |experienced several shocks of less | | |intensity. | | | | xi |viii |destructive earthquake in tayabas province | | |and on marinduque island. it caused great | | |harm in towns of mauban, lucban, and | | |others in northeastern tayabas, and | | |likewise at boac and santa cruz on | | |marinduque. many repetitions of smaller | | |intensity occurred during that day and the | | |following. | | | | i -- | vi |sorsogon province and masbate island. | | |intense earthquake, followed by frequent | | |light repetitions and five strong | | |earthquakes during the months of february | | |and march. | | | | iv | vi |northern luzon. a very strong earthquake | | |throughout northern luzon; that is, in | | |the provinces north of the th parallel | | |of latitude. its center appears to have | | |been near the ilocos coast. | | | | vii | vi |central luzon. strong earthquake in the | | |provinces of pangasinan, union, benguet, | | |nueva vizcaya, isabela, tarlac, zambales, | | |pampanga, nueva ecija, and bulacan. the | | |epicenter was near the shores of | | |casiguran bay. | | | | viii |viii |destructive earthquake in zamboanga, | | |western mindanao. it did considerable | | |damage to masonry buildings and overturned | | |walls. many large fissures opened near the | | |beach of the sea. | | | | ix | vii |violent earthquake in central and eastern | | |luzon, with innumerable repetitions until | | |the end of october. the center lay near | | |casiguran bay. the provinces affected | | |most were northern camarines, tayabas, | | |laguna, rizal, bulacan, nueva ecija, | | |nueva vizcaya, and isabela. | | | | iii | vii |very violent earthquake in abra and the | | |mountain province. destroyed some houses | | |and caused landslides on the mountain | | |sides, ruining rice terraces. it was | | |preceded by feeble shocks and followed by | | |many repetitions until the th. | | | | v |viii |an earthquake which displayed destructive | | |force in the camarines. considerable | | |damage resulted to many buildings in daet, | | |nueva caceres, iriga, buhi, and some other | | |towns. the duration of this earthquake was | | |quite unusual. many repetitions were felt | | |during the following five days. | | | | vi | vi |very strong earthquake throughout central | | |luzon. the meizoseismal area comprised | | |the northern and east-northeastern part | | |of pangasinan province. the shocks had | | |still considerable force on the southern | | |and northern coast of luzon, at distances | | |of about kilometers. | | | ----+--------------------+-----+------------------------------------------ no. | date. |intensity. | | | epicenter and effects. ----+--------------------+-----+------------------------------------------ | _y. m. d. h. m._ | | | vi -- | vii |very violent earthquake in batangas and | | |cavite provinces, in the vicinity of taal | | |volcano. during the hours immediately | | |preceding the quake, seven series of | | |violent shocks were felt. the earthquake | | |cracked many walls in the towns closest | | |to lake bombon. | | | | vii | vii |violent earthquake in camarines, which did | | |no damage, but is remarkable on account of | | |its having been felt with considerable | | |force throughout a great part of luzon and | | |the visayas. it was followed by very many | | |aftershocks of variable intensity, | | |having been recorded during the first | | |hours following the earthquake. | | | | vii | vii |leyte island. very violent earthquake, | | |doing some harm in the northern part of | | |the island. | | | | viii | vi |very strong earthquake of great extension. | | |its epicenter was southwest of luzon, near | | |the western coast of cavite and zambales | | |provinces. it was felt intensely from | | |mindoro to the provinces of union and | | |isabela. | | | | ix | vii |violent earthquake to the west of the | | |gulf of davao, in the neighborhood of apo | | |volcano. many buildings of davao suffered | | |seriously. repetitions were frequent | | |until the d. | | | | vii | x |surigao peninsula. destructive earthquake, | | |with disastrous results to buildings and | | |the topography of the region. not a single | | |stone building remained inhabitable, | | |although some of them, like the church, | | |government house, and prison at surigao, | | |were of most solid construction. besides | | |the opening of innumerable fissures and | | |vast landslides on the coasts and in the | | |mountains, there occurred extensive | | |subsidences: several accurate observations | | |seem to prove that a great part of the | | |peninsula was depressed by about feet. | | |in short, this earthquake was one of those | | |which produced the greatest changes of | | |topography experienced in the philippines. | | |there followed other very strong quakes on | | |july , , and , and august , with | | |countless repetitions of less importance | | |during several months. from july to | | |occurred on the average perceptible | | |shocks per day. | | | | viii -- | vi |district of cotabato, mindanao. very | | |strong earthquake which closed a series of | | |quakes which had begun on the th of the | | |month. of these, two felt on the th and | | |one on the st had been rather intense. | | | | ix -- -- | vi |district of davao, mindanao. very strong | | |earthquake followed by some repetitions. | | |on the th of the same month a somewhat | | |less intense earthquake had been felt in | | |the same region. | | | | x -- | vii |ilocos norte. very violent earthquake | | |which damaged buildings in the town of | | |baccarra. | | | | xii -- -- | vii |ilocos norte. very violent earthquake | | |resulting in damaged buildings at laoag | | |and other towns of the province. | | | | iii | vi |very strong earthquake in eastern panay | | |and the northwestern part of negros | | |island. | | | | vii |viii |eastern part of luzon. destructive | | |earthquake in the provinces of tayabas | | |and laguna. it damaged to some extent all | | |masonry structures, both public and | | |private, in the towns east of lake bay. | | | ----+--------------------+-----+------------------------------------------ no. | date. |intensity. | | | epicenter and effects. ----+--------------------+-----+------------------------------------------ | _y. m. d. h. m._ | | | vii | ix |central and southern luzon. destructive | | |earthquake affecting the provinces of | | |tayabas, cavite, laguna, rizal, bulacan, | | |bataan, pampanga, tarlac, nueva ecija, and | | |pangasinan. in manila, as well as in the | | |towns of the provinces mentioned, the | | |earthquake did incalculable harm to | | |buildings, besides causing subsidences, | | |fissures, lateral displacements and | | |similar effects, especially in the | | |alluvial lands along the banks of the | | |rivers pasig, the great and little | | |pampanga, and the agno. | | | | vii |viii |earthquake of destructive violence in the | | |towns surrounding lake bay, especially in | | |those south and west of the lake. | | | | | |within the epicentral region of the three | | |preceding earthquakes, which measures | | |about kilometers from north to south | | |and kilometers from east to west, | | |severe damage was done to the principal | | |stone buildings, such as churches, | | |_conventos_, court-houses, schools, and a | | |few private houses, of of the city | | |principal towns. in the of manila some | | |public buildings (administration | | |buildings, barracks, churches, | | |monasteries, and colleges) and about | | |private houses of strong materials were | | |either wrecked or badly damaged. | | |fortunately the number of victims was not | | |in proportion to the magnitude of the | | |disaster, neither in manila nor in the | | |provinces. from the various reports | | |published at the time we conclude that | | |the number of killed did not exceed , | | |nor that of the injured . | | | | ix | vi |strong earthquake along the zambales | | |coast, western luzon. frequent | | |repetitions until october d. | | | | vii | vi |very strong earthquake in southern panay | | |and northwestern negros. | | | | vii | vii |violent earthquake in the province of | | |nueva vizcaya. this was the first violent | | |forerunner of the innumerable shocks which | | |during the months of august, september, | | |and october were to spread devastation and | | |terror throughout this province. | | | | ix | ix |destructive earthquake in nueva vizcaya. | | | | ix |viii |destructive earthquake in nueva vizcaya. | | | | ix |viii |destructive earthquake in nueva vizcaya. | | | | ix |viii |destructive earthquake in nueva vizcaya. | | | | | |this memorable seismic period of nueva | | |vizcaya ended after october . during | | |august and september a missionary made a | | |list comprising over distinct | | |earthquakes, without including countless | | |repetitions of smaller intensity. the | | |effects of these earthquakes were more | | |notable by the alterations in the | | |topography of the region than by the | | |damage done to buildings, as the latter | | |were of wood and thatched with cogon | | |grass. the inhabitants were | | |terror-stricken and the authorities had | | |to work hard to prevent a general exodus | | |from the country. | | | | iv | vi |district of cotabato, mindanao. violent | | |earthquake, preceded by subterraneous | | |rumblings and followed by frequent | | |repetitions. already during march some | | |very strong shocks had preceded. | | | | x | vii |violent earthquake in camarines province | | |with several repetitions. | | | ----+--------------------+-----+------------------------------------------ no. | date. |intensity. | | | epicenter and effects. ----+--------------------+-----+------------------------------------------ | _y. m. d. h. m._ | | | xii -- -- | vii |very violent earthquake in the north of | | |cebu island and southern masbate. | | | | ii | vii |very violent earthquake in nueva vizcaya | | |and benguet provinces. it had been | | |preceded by a strong shock at h m of | | |the th. | | | | i | vii |very violent earthquake near the southern | | |coasts of camarines province, followed by | | |a strong quake on the th and by | | |numerous repetitions. | | | | vi -- -- | vi |very strong earthquake in the province of | | |misamis, northern mindanao. repeated with | | |the same intensity at h and h. | | | | x | vi |very strong earthquake in the whole south | | |and southeast of luzon, chiefly in the | | |provinces of laguna, tayabas, camarines, | | |albay, and sorsogon; likewise on masbate | | |island. many repetitions occurred until | | |the end of november. | | | | xii -- | vi |samar, leyte, and northeast mindanao. very | | |strong earthquake, with very severe | | |repetitions on the th, th, and th. | | | | ii |viii |east coast of mindanao. destructive | | |earthquake, which did extensive damage to | | |the churches and other buildings of stone | | |or wood and caused mighty fissures and | | |landslides in the mountains as well as in | | |the scarps of the pacific coast. | | | | vii | ix |northwestern mindanao. destructive | | |earthquake which ruined several buildings | | |in the towns and villages of the dapitan | | |district. the origin lay in the | | |east-northeastern part of the sulu sea. | | |the disturbance was felt strongly in | | |nearly all of the visayan islands, in | | |western mindanao and the sulu archipelago. | | |repetitions were frequent until the end of | | |october, those of july , september , | | |september , and october being very | | |intense. | | | | ix -- | vi |northeastern mindanao and southeastern | | |leyte. very strong earthquake, followed by | | |many repetitions. | | | | xi | vii |very violent earthquake in the provinces | | |of nueva vizcaya, isabela, and benguet, | | |followed by strong repetitions on | | |december , , and . | | | | iv -- | vi |very strong earthquake in the southeast | | |of panay and northwest of negros islands. | | | | ii -- | ix |panay island. destructive earthquake, | | |causing notable damages, especially in | | |the towns of the provinces of iloilo and | | |capiz. the two days following the | | |earthquake brought many aftershocks. | | | | iii |viii |camarines province. destructive earthquake | | |doing considerable harm in several towns | | |in the vicinity of nueva caceres. the th | | |witnessed a very intense repetition, while | | |lighter aftershocks were frequent until | | |the month of may. | | | | i | vi |very strong earthquake in eastern | | |mindanao, which had its epicenter in the | | |agusan river valley. | | | | viii | vi |northeastern luzon. very strong | | |earthquake, especially in the provinces | | |of cagayan and isabela, followed by many | | |repetitions of varying intensity. | | | ----+--------------------+-----+------------------------------------------ no. | date. |intensity. | | | epicenter and effects. ----+--------------------+-----+------------------------------------------ | _y. m. d. h. m._ | | | i | vii |northeastern mindanao. violent earthquake | | |in the districts of surigao and butuan. | | |repeated with equal force at h m of | | |the th, doing slight damage to buildings | | |in surigao, placer, and gigaquit, and | | |opening numerous fissures in the ground. | | |repetitions were very frequent throughout | | |the month, more than having been | | |recorded until the d. | | | | ii |viii |western mindanao. destructive earthquake | | |whose origin lay south of illana bay. it | | |was felt with equal force at zamboanga and | | |cotabato, each at a distance of more than | | | kilometers from the epicenter, but did | | |no harm worth mentioning. | | | | v |viii |destructive earthquake in the province of | | |batangas and northern mindoro. it wrecked | | |the church at ibaan and severely damaged | | |the church and other buildings in | | |batangas, bauang, calapan, and several | | |other towns. | | | | x | vii |very violent earthquake throughout eastern | | |mindanao, with epicenter in the valley of | | |the agusan river. it was very perceptible | | |in every part of the island and on many of | | |the visayas. | | | | ii |viii |destructive earthquake in northern leyte | | |which split walls in barugo, carigara, and | | |other towns, and produced large fissures | | |in the lowlands along the coast. on the | | | th and th occurred strong and more | | |than light repetitions. | | | | iv | vi |northern luzon. very strong earthquake in | | |ilocos norte and sur, the mountain | | |province, cagayan, and isabela. a | | |repetition occurring at h developed the | | |same intensity. | | | | vi | vii |very violent earthquake in eastern | | |mindanao whose center was in the agusan | | |river valley. slightly damaged buildings | | |at davao and butuan, situated | | |kilometers south and north, respectively, | | |of the focus. | | | | iii -- -- |viii |batanes islands. destructive earthquake. | | |all that is known of the effects is that | | |it wrecked some buildings at santo domingo | | |and other towns on batan island. | | | | iii | x |disastrous earthquake in the provinces of | | |pangasinan, union, and benguet. it created | | |great havoc in the masonry buildings, such | | |as churches, _conventos_, court-houses, | | |and schools, besides a few private houses, | | |of of the principal towns within the | | |meizoseismic area, produced great fissures | | |and extensive subsidences in the alluvial | | |plains, and many landslides in the steep | | |mountains of northern pangasinan. luckily | | |the falling buildings killed only one or | | |two persons. repetitions were frequent up | | |to the end of the month; of these three | | |occurring on the th and one each on the | | | th and th were of exceptional | | |intensity. | | | | iii | vii |very violent earthquake in the region | | |mentioned under no. . wrecked some | | |buildings damaged by the preceding. | | | | iii | vi |central luzon. very strong earthquake in | | |the provinces of nueva vizcaya, benguet, | | |and pangasinan. | | | | iv | vi |very strong earthquake in camarines, | | |albay, sorsogon, masbate, and northern | | |samar. its epicenter was close to masbate | | |island. | | | | vi | vii |violent earthquake in the whole western | | |part of mindanao, proceeding from the | | |neighborhood of illana bay. | | | ----+--------------------+-----+------------------------------------------ no. | date. |intensity. | | | epicenter and effects. ----+--------------------+-----+------------------------------------------ | _y. m. d. h. m._ | | | vi | x |disastrous earthquake in the agusan river | | |valley. the fact that there was no general | | |destruction of buildings with heavy loss | | |of life is due solely to the circumstance | | |that the region affected contained only | | |structures of bamboo and nipa. the effects | | |of the convulsions on the topography of | | |the region give an idea of what the | | |consequences of the quake might have been | | |had it found another class of buildings. | | |there are indications that in the southern | | |part of the valley an area of many square | | |kilometers subsided to a considerable | | |extent. repetitions were frequent | | |throughout an entire year. | | | | vii | vii |very violent earthquake in the valley of | | |the agusan river. | | | | xii | vi |very strong earthquake in southeastern | | |luzon, northern samar, and masbate. the | | |epicenter lay northeast of masbate island, | | |close to capul island, on which latter the | | |quake was violent. repeated at h m of | | |the same day. | | | | ii |viii |destructive earthquake in southeastern | | |mindanao, having its epicenter in the | | |region east of davao gulf. it produced | | |many fissures and displacements in the | | |mountains and cracked a few houses of wood | | |in the towns of mati and sigaboy. the | | |aftershocks continued on the th and | | | th, occurring at intervals of about | | |minutes. | | | | ii | vi |very strong earthquake in the valley of | | |the agusan river which was repeated with | | |the same intensity at h m of the th. | | | | iv | vi |very strong earthquake in central luzon, | | |especially in nueva ecija, pangasinan, and | | |benguet. | | | | vi |viii |agusan river valley. destructive | | |earthquake whose effects were similar to | | |those of the earthquake on june , | | |(no. ). the aftershocks, which had been | | |felt ever since the latter disturbance, | | |increased in force and frequency. | | | | vi | vii |violent earthquake in agusan river valley. | | |repeated with the same intensity at h | | | m. | | | | v | vii |northern mindoro. very violent earthquake | | |which damaged considerably the church and | | |_convento_ at calapan, these being the | | |only masonry buildings in the town. it was | | |repeated with great intensity at h m | | |of the same day and at h m of the th. | | |on the th more than aftershocks of | | |variable intensity were counted. | | | | vi | vii |northern mindoro. very violent earthquake | | |which ruined part of the church at calapan. | | |severe repetitions occurred at h m and | | | h m of the th. | | | | ix | vii |northwestern luzon. very violent | | |earthquake which damaged several buildings | | |in laoag and other towns of ilocos norte. | | |strong repetitions at h m and h m. | | | | i | vi |very strong earthquake in the mountain | | |province and the provinces of isabela and | | |cagayan. numerous aftershocks followed | | |during the day. | | | | ii | vii |agusan river valley. violent earthquake | | |with daily aftershocks during the rest of | | |the month. | | | ----+--------------------+-----+------------------------------------------ no. | date. |intensity. | | | epicenter and effects. ----+--------------------+-----+------------------------------------------ | _y. m. d. h. m._ | | | iv |viii |agusan river valley. destructive | | |earthquake. | | | | v |viii |masbate island. destructive earthquake | | |which heavily damaged several buildings, | | |bridges, and wharves. a strong repetition | | |occurred at h m of the th. weak | | |aftershocks were frequent until the th. | | | | viii |viii |ilocos sur. destructive earthquake with | | |epicentric area of kilometers in length | | |and kilometers in width. the towns | | |which suffered most were those between | | |candon and vigan. | | | | ix | vii |very violent earthquake in northwestern | | |mindanao. it produced fissures in the | | |ground and slightly injured buildings in | | |the district of dapitan. more than | | |aftershocks of varying intensity were | | |recorded during the next hours. | | | | ix | ix |disastrous earthquake in the district of | | |zamboanga, basilan, and jolo islands. it | | |wrought great destruction of buildings and | | |produced fissures, landslides, and similar | | |effects. a formidable "tsunami" (tidal | | |wave) claimed hundreds of victims on the | | |western shores of basilan. this "tsunami" | | |was the most imposing recorded in the | | |seismological history of the archipelago. | | |there followed innumerable aftershocks | | |during months, having been counted | | |before the middle of october, of which | | |those on september , , , , and , | | |and october and deserve special | | |mention on account of their great | | |intensity. | | | | x | vi |very strong earthquake in the district of | | |davao. | | | | x | ix |northern samar. destructive earthquake | | |which damaged to a considerable extent | | |buildings in sulat, palapag, catubic, | | |oras, gandara, and laoang, towns near the | | |northern and northeastern coasts of the | | |island, and also produced vast fissures | | |and other notable effects which resulted | | |in the destruction of various bridges and | | |roads. | | | | x |viii |northern samar. most violent earthquake, | | |with results similar to those of the | | |preceding, though less severe. countless | | |aftershocks continued until the following | | |april, those of october , , and | | |being the strongest. | | | | xi | vii |very violent earthquake, but of very | | |limited epicentral area, in ilocos sur, | | |northwestern luzon. it wrecked the church | | |at candon. | | | | i | vii |sulu archipelago. violent earthquake, | | |preceded by two of less severity at | | | h m and h m. | | | | xii | vi |very strong earthquake in the agusan river | | |valley. | | | | viii | vi |very strong earthquake in masbate and | | |northern cebu. | | | | ix | vii |very violent earthquake in eastern | | |tayabas; damaged the church of calauag and | | |other towns on the eastern shores of lamon | | |bay. large fissures opened on the beach | | |and the water became very turbid; dead | | |fishes were likewise found. | | | | xii | vii |very violent earthquake in southern luzon. | | |some towns in batangas province suffered | | |slight damage. | | | ----+--------------------+-----+------------------------------------------ no. | date. |intensity. | | | epicenter and effects. ----+--------------------+-----+------------------------------------------ | _y. m. d. h. m._ | | | vii | vi |northeastern mindanao. very strong | | |earthquake with epicenter in butuan bay. | | |two repetitions, which occurred on the | | | th, showed little intensity. | | | | viii | x |southwestern mindanao. destructive | | |earthquake in the lanao and cotabato | | |districts. it proceeded from the center | | |which lies in the northern part of illana | | |bay, and caused heavy damage to all the | | |buildings in the towns and in the moro | | |villages and strongholds within the | | |meizoseismal region. the effects were | | |extraordinary on land as well as within | | |the bay; in the latter the telegraph | | |cables were found broken and buried by | | |débris. it is assumed as certain that | | |there were many lives lost in the moro | | |forts, but their number is not known. the | | |aftershocks were so frequent that some | | |could be counted within the first days | | |after the disaster, some or of these | | |reaching force vi and vii. | | | | viii | ix |province of iloilo, panay. destructive | | |earthquake which seriously damaged the | | |churches and other buildings in the towns | | |of maasin, calinog, and janiuay. many | | |fissures opened in the mountains and | | |extensive subsidences took place. the | | |disturbance was preceded by an | | |extraordinary noise, which was audible at | | |great distances from the epicentral | | |region. the reports do not mention a | | |single aftershock. | | | | xi | vii |southwestern luzon. very violent | | |earthquake in the provinces of batangas, | | |cavite, bataan and zambales. the effects | | |were confined to slight damages to several | | |buildings in batangas, taal, and other | | |towns south and west of taal volcano. the | | |epicenter was near the coasts of | | |southwestern luzon, where intense | | |subterranean noises were heard. the | | |aftershocks which have been recorded were | | |of little intensity. | | | | v | vi |southeastern mindanao. very intense | | |earthquake, having its center to the | | |northwest of davao gulf. the shock was | | |perceptible throughout the island. | | | | xii |viii |destructive earthquake in the region east | | |of davao gulf which damaged many houses in | | |mati, caraga, sigaboy, etc. large fissures | | |opened and several displacements occurred | | |in the limestone layers of the pacific | | |coast near caraga. a few aftershocks were | | |felt on the th and th. | | | | x | vii |very violent earthquake in the southern | | |part of the agusan river valley. | | | | x | vii |northern luzon. very violent earthquake | | |whose epicenter lay in the northern part | | |of the mountain province. slight damage | | |was done in several towns of ilocos norte | | |and cagayan, situated near the central | | |cordillera. | | | | xii | vii |very violent earthquake in southeastern | | |luzon and the eastern visayas. its | | |epicenter lay underneath the sea, to | | |the south of masbate island. | | | ----+--------------------+-----+------------------------------------------ no. | date. |intensity. | | | epicenter and effects. ----+--------------------+-----+------------------------------------------ | _y. m. d. h. m._ | | | xii |viii |agusan river valley. destructive | | |earthquake, which left its history written | | |on the topography of the region, but made | | |little impression upon the buildings, as | | |these were of bamboo and palm leaves. the | | |shock was well felt throughout mindanao | | |and the eastern visayas. | | | | vi | vi |batanes islands. violent earthquake | | |accompanied by subterranean noises. it | | |proceeded from a center situated south of | | |balintang channel, and showed likewise | | |considerable intensity in northern luzon. | | |the th and st witnessed many | | |aftershocks. | | | | iv | ix |camarines province. destructive earthquake | | |which, within an area of kilometers | | |in length and in width, wrecked many | | |masonry buildings, produced great | | |fissures in the ground and landslides in | | |the mountains. only two cases of death | | |and a few of injuries received have been | | |recorded. | | | | iv | vii |very violent earthquake in the same region | | |as the preceding. it completed the ruin of | | |some buildings weakened by its | | |predecessor. these two earthquakes were | | |followed by numerous aftershocks of | | |varying intensity until the month of july. | | | | v |viii |southern leyte. very violent earthquake | | |with a very intense repetition at h | | | m. the meizoseismic area had a diameter | | |of only kilometers, determined by an | | |extinct volcano, mount cabalían, which is | | |situated in this part of the island. from | | |may to some earthquakes of | | |various intensities were felt. no enhanced | | |activity was observed in the volcano, but | | |many fissures and great landslides were | | |produced on its slopes. | | | | v |viii |northern luzon. very violent earthquake | | |whose center was in the northern part of | | |the central cordillera (mountain | | |province). it did considerable damage in | | |the provinces of ilocos norte and cagayan. | | |the central part of the epicentral region, | | |where the effects must have been more | | |severe, is inhabited exclusively by wild | | |tribes. no aftershocks have been recorded. | | | | xi | ix |camarines province. destructive earthquake | | |which ruined nearly all the masonry | | |buildings of the towns within an area of | | |some kilometers in length and in | | |width. within this small region, composed | | |of recent alluvial soil and traversed by | | |the quinali river, a great number of | | |fissures opened and various subsidences | | |took place. | | | | i | vi |western leyte. very strong earthquake | | |proceeding from a submarine center not | | |far from ormoc bay. it was followed by | | |two very intense aftershocks at h m and | | | h m and many of less severity until | | |the d. | | | | iii | vi |agusan river valley. very strong | | |earthquake. | | | | v | vi |very strong earthquake in western | | |mindanao and the sulu archipelago. | | | ----+--------------------+-----+------------------------------------------ no. | date. |intensity. | | | epicenter and effects. ----+--------------------+-----+------------------------------------------ | _y. m. d. h. m._ | | | ii | vi |very strong earthquake in the region | | |south of butuan bay. its epicentral area | | |was very small, comprising only butuan | | |and the towns close to the mouth of the | | |agusan river. | | | | iii |viii |eastern mindanao. very violent earthquake | | |whose epicenter stretched in a narrow | | |belt along parallel ° ' latitude north | | |from the agusan river to the pacific | | |coast. it did severe damage to the church | | |and _convento_ of bislig and in some | | |neighboring towns. | | | | iv | vi |very strong earthquake in the extreme | | |southeast of luzon, having its center | | |underneath the sea to the south of | | |catanduanes island. | | | appendix. earthquakes in the marianas islands. ----+--------------------+-----+------------------------------------------ no. | date. |intensity. | | | epicenter and effects. ----+--------------------+-----+------------------------------------------ | _y. m. d. h. m._ | | | iv -- -- -- |viii |destructive earthquake in the marinas or | | |ladrones group of islands. ruined many | | |buildings at agaña, guam island. | | | | v -- -- -- |viii |destructive earthquake on guam island. | | |considerable havoc and great panic at | | |agaña and in the other towns of the | | |island. | | | | i | ix |destructive earthquake. laid in ruins all | | |the masonry buildings on the islands--the | | |church, _convento_, and college at agaña, | | |the churches at umata, pago, and agat, | | |together with a great number of houses. | | |immense fissures opened in many places, | | |and an extraordinary commotion of short | | |duration was observed in the sea. there | | |followed countless aftershocks, some of | | |them very intense; from january to | | |march no fewer than were actually | | |counted. | | | | vii | vii |violent earthquake. did great damage to | | |the tile roofs at agaña and in other towns | | |on the island of guam. | | | | xii -- | vi |guam. violent earthquake causing great | | |alarm but little harm. | | | | vi -- | vi |guam. very strong earthquake. | | | | v | vi |guam. two very strong shocks at an | | |interval of seconds. the fact that they | | |did no damage has been attributed to the | | |absence of horizontal movements. | | | | v |viii |destructive earthquake which severely | | |damaged the masonry buildings in agaña and | | |other towns, produced many fissures and | | |displacements on the coasts and in other | | |places. the sea retired suddenly, but no | | |devastating alternations of floods and | | |ebbs followed. the few aftershocks which | | |occurred during the two following days | | |were feeble. | | | | ix | ix |destructive earthquake which wrecked or | | |damaged very seriously all the buildings | | |at agaña, guam. great fissures opened in | | |the ground and displacements occurred | | |which resulted in the destruction of | | |several bridges. similar effects are | | |reported from saipan island. personal | | |accidents were limited to a few injured. | | |aftershocks were very numerous during the | | |first days after the earthquake. | | | | xii | vi |very strong earthquake lasting over a | | |minute. at this time the aftershocks of | | |the earthquake of september were still | | |continuing. | | | | ii | vii |guam. violent earthquake which damaged to | | |some extent the government house at agaña. | | |two distinct series of shocks were | | |observed, having a total duration of more | | |than a minute. | | | ----+--------------------+-----+------------------------------------------ no. | date. |intensity. | | | epicenter and effects. ----+--------------------+-----+------------------------------------------ | _y. m. d. h. m._ | | | xii |viii |guam. destructive earthquake. two shocks | | |lasting seconds, of which the second | | |was the more severe. direction of the | | |shocks se-nw. in agaña practically all the | | |east and west walls of native mortar | | |houses were badly cracked. in nearly every | | |house articles on shelves of these walls | | |were thrown down, while those on the north | | |and south sides remained in place. the | | |women's hospital, built of local mortar, | | |was so badly injured as to require tearing | | |down; its tiled roof slid off to westward | | |and the worst cracks were in the east | | |wall. many ceiling boards in different | | |houses were shaken down. several fissures | | |opened in the ground, from one of which, | | |near the river, came a large flow of | | |water. the river bed sank in several | | |places. the passing wave could be seen | | |distinctly as it crossed the plaza, and | | |the station ship in the harbor reported | | |having felt the shock. no damage of | | |importance was done in the other towns on | | |the island. the buildings of the cable | | |station at sumay, constructed of | | |reinforced concrete, were not injured, but | | |a few objects were thrown down and the | | |steel water towers could be seen swaying. | | |no shocks were noticed before or after the | | |earthquake, nor was anything extraordinary | | |observed in the sea. the disturbance was | | |not felt at yap, western carolines. no | | |information from the other islands. | | | [illustration: (map of the philippine islands)] [illustration: earthquake map of the philippine islands - ] * * * * * +--------------------------------------------------------------+ | typographical errors corrected in text: | | | | page : neihgboring replaced with neighboring | | page : iloílo replaced with iloilo | | page : iloílo replaced with iloilo | | page : damage replaced with damaged | | | +--------------------------------------------------------------+ * * * * * note: project gutenberg also has an html version of this file which includes the original illustrations. see -h.htm or -h.zip: (http://www.gutenberg.org/files/ / -h/ -h.htm) or (http://www.gutenberg.org/files/ / -h.zip) the contemporary science series. edited by havelock ellis. volcanoes: past and present. [illustration: fig. .--eruption of vesuvius, - ] volcanoes: past and present. by edward hull, m.a., ll.d., f.r.s. examiner in geology to the university of london. with illustrations and plates of rock-sections. london: walter scott, limited, , warwick lane, paternoster row. . _by the same author._ the coal-fields of great britain: their history, structure, and resources. th edit. ( .) e. stanford. the physical history of the british isles. with a dissertation on the origin of western europe and of the atlantic ocean. ( .) e. stanford. the physical geology and geography of ireland. nd edit. ( .) e. stanford. treatise on the building and ornamental stones of great britain and foreign countries. ( .) macmillan and co. memoir on the physical geology and geography of arabia-petræa, palestine, and adjoining districts. ( .) committee of the palestine exploration fund. mount seir, sinai, and western palestine. being a narrative of a scientific expedition, - . ( .) committee of the palestine exploration fund. text-book of physiography. ( .) c. w. deacon and co. sketch of geological history. ( .) c. w. deacon and co. preface. it has not been my object to present in the following pages even an approximately complete description of the volcanic and seismic phenomena of the globe; such an undertaking would involve an amount of labour which few would be bold enough to attempt; nor would it be compatible with the aims of the _contemporary science series_. i have rather chosen to illustrate the most recent conclusions regarding the phenomena and origin of volcanic action, by the selection of examples drawn from the districts where these phenomena have been most carefully observed and recorded under the light of modern geological science. i have also endeavoured to show, by illustrations carried back into later geological epochs, how the volcanic phenomena of the present day do not differ in kind, though they may in degree, from those of the past history of our globe. for not only do the modes of eruption of volcanic materials in past geological times resemble those of the present or human epoch, but the materials themselves are so similar in character that it is only in consequence of alterations in structure or composition which the original materials have undergone, since their extrusion, that any important distinctions can be recognised between the volcanic products of recent times and those of earlier periods. i have, finally, endeavoured to find an answer to two interesting and important questions: ( ) are we now living in an epoch of extraordinary volcanic energy?--a question which such terrible outbursts as we have recently witnessed in japan, the malay archipelago, and even in italy, naturally suggest; and ( ) what is the ultimate cause of volcanic action? on this latter point i am gratified to find that my conclusions are in accordance with those expounded by one who has been appropriately designated "the nestor of modern geology," professor prestwich. within the last few years the study of the structure and composition of volcanic rocks, by means of the microscope brought to bear on their translucent sections, has added wonderfully to our knowledge of such rocks, and has become a special branch of petrological investigation. commenced by sorby, and carried on by allport, zirkel, rosenbusch, von lasaulx, teall, and many more enthusiastic students, it has thrown a flood of light upon our knowledge of the mutual relations of the component minerals of igneous masses, the alteration these minerals have undergone in some cases, and the conditions under which they have been erupted and consolidated. but nothing that has been observed has tended materially to alter conclusions arrived at by other processes of reasoning regarding volcanic phenomena, and for these we have to fall back upon observations conducted in the field on a more or less large scale, and carried on before, during, and after eruptions. macroscopic and microscopic observations have to go hand in hand in the study of volcanic phenomena. e. h. contents. part i. _introduction._ page chap. i. historic notices of volcanic action - " ii. form, structure, and composition of volcanic mountains - " iii. lines and groups of active volcanic vents - " iv. mid-ocean volcanic islands - part ii. _european volcanoes._ chap. i. vesuvius - " ii. etna - " iii. the lipari islands, stromboli - " iv. the santorin group - " v. european extinct or dormant volcanoes - " vi. extinct volcanoes of central france - " vii. the volcanic district of the rhine valley - part iii. _dormant or moribund volcanoes of other parts of the world._ chap. i. dormant volcanoes of palestine and arabia - " ii. the volcanic regions of north america - " iii. volcanoes of new zealand - part iv. _tertiary volcanic districts of the british isles._ chap. i. antrim - " ii. succession of volcanic eruptions - " iii. island of mull and adjoining coast - " iv. isle of skye - " v. the scuir of eigg - " vi. isle of staffa - part v. _pre-tertiary volcanic rocks._ chap. i. the deccan trap-series of india - " ii. abyssinian table-lands - " iii. cape colony - " iv. volcanic rocks of past geological periods of the british isles - part vi. _special volcanic and seismic phenomena._ chap. i. the eruption of krakatoa in - " ii. earthquakes - part vii. _volcanic and seismic problems._ chap. i. the ultimate cause of volcanic action - " ii. lunar volcanoes - " iii. are we living in an epoch of special volcanic activity? - appendix. a brief account of the principal varieties of volcanic rocks - index illustrations. fig. . eruption of vesuvius, - _frontispiece_ " . cotopaxi _page_ " . volcanic cone of orizaba " map of the world, showing active and extinct volcanoes " " . teneriffe, seen from the ocean " " . view of the summit of teneriffe " " . probable aspect of vesuvius at beginning of christian era " " . view of vesuvius before " " . map of district bordering bay of naples " " . view of vesuvius in " " . ideal section through etna " " . map of the lipari islands " " . the island of vulcano in eruption " " . ideal section through gulf of santorin " " . bird's-eye view of gulf of santorin " " . ground plan of rocca monfina " " . geological section of tiber valley at rome " " . generalised section through the vale of clermont " fig. . view of puy de dôme and neighbouring volcanoes _page_ " . mont demise, seen from the s.e. " " . sketch map of rhenish area in the miocene epoch " " . the volcanic range of the siebengebirge " " . section of extinct crater of the roderberg " " . plan and section of the laacher see " " . extinct craters in the jaulân " " . mount shasta " " . forms of volcanic tuff-cones, auckland " " . "the white rocks," portrush, co. antrim " " . section across the volcanic plateau of antrim " " . section at templepatrick " " . cliff above the giant's causeway " " . the giant's causeway, co. antrim " " . "the chimneys," north coast of antrim " " . section at alt na searmoin, mull " " . view of the scuir of eigg from the east " map of volcanic band of the moluccas " " . map of the krakatoa group of islands " " . section from verlaten island through krakatoa " fig. . isoseismals of the charleston earthquake _page_ " . photograph of the moon's surface " " . portion of the moon's surface " _plates._ i. & ii. magnified sections of vesuvian lavas. iii. & iv. magnified sections of volcanic rocks. volcanoes: past and present. part i. introduction. chapter i. historic notices of volcanic action. there are no manifestations of the forces of nature more calculated to inspire us with feelings of awe and admiration than volcanic eruptions preceded or accompanied, as they generally are, by earthquake shocks. few agents have been so destructive in their effects; and to the real dangers which follow such terrestrial convulsions are to be added the feelings of uncertainty and revulsion which arise from the fact that the earth upon which we tread, and which we have been accustomed to regard as the emblem of stability, may become at any moment the agent of our destruction. it is, therefore, not surprising that the ancient greeks, who, as well as the romans, were close observers of the phenomena of nature, should have investigated the causes of terrestrial disturbances, and should have come to some conclusions upon them in accordance with the light they possessed. these terrible forces presented to the greeks, who clothed all the operations of nature in poetic imagery and deified her forces, their poetical and mystical side; and as there was a deity for every natural force, so there was one for earthquakes and volcanoes. vulcan, the deformed son of juno (whose name bears so strange a resemblance to that of "the first artificer in iron" of the bible, tubal cain), is condemned to pass his days under mount etna, fabricating the thunderbolts of jove, and arms for the gods and great heroes of antiquity. the pythagoreans appear to have held the doctrine of a central fire (meson pyr) as the source of volcanic phenomena; and in the dialogues of plato allusion is made to a subterranean reservoir of lava, which, according to simplicius, was in accordance with the doctrine of the pythagoreans which plato was recounting.[ ] thucydides clearly describes the effect of earthquakes upon coast-lines of the grecian archipelago, similar to that which took place in the case of the earthquake of lisbon, the sea first retiring and afterwards inundating the shore. pliny supposed that it was by earthquake avulsion that islands were naturally formed. thus sicily was torn from italy, cyprus from syria, euboea from boeotia, and the rest; but this view was previously enunciated by aristotle in his "peri kosmou," where he states that earthquakes have torn to pieces many parts of the earth, while lands have been converted into sea, and that tracts once covered by the sea have been converted into dry land. but the most philosophical views regarding terrestrial phenomena are those given by ovid as having been held by pythagoras (about b.c. ). in the _metamorphoses_ his views regarding the interchange of land and sea, the effects of running water in eroding valleys, the growth of deltas, the effect of earthquakes in burying cities and diverting streams from their sources, are remarkable anticipations of doctrines now generally held.[ ] but what most concerns us at present are his views regarding the changes which have come over volcanic mountains. in his day vesuvius was dormant, but etna was active; so his illustrations are drawn from the latter mountain; and in this connection he observes that volcanic vents shift their position. there was a time, he says, when etna was not a burning mountain, and the time will come when it will cease to burn; whether it be that some caverns become closed up by the movements of the earth, or others opened, or whether the fuel is finally exhausted.[ ] strabo may be regarded as having originated the view, now generally held, that active volcanoes are safety-valves to the regions in which they are situated. referring to the tradition recorded by pliny, that sicily was torn from italy by an earthquake, he observes that the land near the sea in those parts was rarely shaken by earthquakes, since there are now orifices whereby fire and ignited matters and waters escape; but formerly, when the volcanoes of etna, the lipari islands, ischia, and others were closed up, the imprisoned fire and wind might have produced far more violent movements.[ ] the account of the first recorded eruption of vesuvius has been graphically related by the younger pliny in his two letters to tacitus, to which i shall have occasion to refer further on.[ ] these bring down the references to volcanic phenomena amongst ancient authors to the commencement of the christian era; from all of which we may infer that the more enlightened philosophers of antiquity had a general idea that eruptions had their origin in a central fire within the interior of the earth, that volcanic mountains were liable to become dormant for long periods, and afterwards to break out into renewed activity, that there existed a connection between volcanic action and earthquakes, and that volcanoes are safety-valves for the regions around. it is unnecessary that i should pursue the historical sketch further. those who wish to know the views of writers of the middle ages will find them recorded by sir charles lyell.[ ] the long controversy carried on during the latter part of the eighteenth century between "neptunists," led by werner on the one side, and "vulcanists," led by hutton and playfair on the other, regarding the origin of such rocks as granite and basalt, was finally brought to a close by the triumph of the "vulcanists," who demonstrated that such rocks are the result of igneous fusion; and that in the cases of basalt and its congeners, they are being extruded from volcanic vents at the present day. the general principles for the classification of rocks as recognised in modern science may be regarded as having been finally established by james hutton, of edinburgh, in his _theory of the earth_,[ ] while they were illustrated and defended by professor playfair in his work entitled, _illustrations of the huttonian theory of the earth_,[ ] although other observers, such as desmarest, collini, and guettard, had in other countries come to very clear views on this subject. the following are some of the more important works on the phenomena of volcanoes and earthquakes published during the present century:--[ ] . poulett scrope, f.r.s., _considerations on volcanoes_ ( ). this work is dedicated to lyell, his fellow-worker in the same department of science, and was undertaken, as he says, "in order to help to dispel that signal delusion as to the mode of action of the subtelluric forces with which the elevation-crater theory had mystified the geological world." the second edition was published in . . this was followed by the admirable work, _on the extinct volcanoes of central france_, published in ( nd edition, ), and is one of the most complete monographs on a special volcanic district ever written. . dr. samuel hibbert, _history of the extinct volcanoes of the basin of neuwied on the lower rhine_ ( ). dr. hibbert's work is one of remarkable merit, if we consider the time at which it was written. for not only does it give a clear and detailed account of the volcanic phenomena of the eifel and the lower rhine, but it anticipates the principles upon which modern writers account for the formation of river valleys and other physical features; and in working out the physical history of the rhine valley below mainz, and its connection with the extinct volcanoes which are found on both banks of that river, he has taken very much the same line of reasoning which was some years afterwards adopted by sir a. ramsay when dealing with the same subject. it does not appear that the latter writer was aware of dr. hibbert's treatise. . leopold von buch, _description physique des iles canaries_ ( ), translated from the original by c. boulanger ( ); _geognostische reise_ (berlin, ), vols.; and _reise durch italien_ ( ). from a large number of writings on volcanoes by this distinguished traveller, whom alexander von humboldt calls "dem geistreichen forscher der natur," the above are selected as being the most important. that on the canaries is accompanied by a large atlas, in which the volcanoes of teneriffe, palma, and lancerote, with some others, are elaborately represented, and are considered to bear out the author's views regarding the formation of volcanic cones by elevation or upheaval. the works dealing with the volcanic phenomena of central and southern italy are also written with the object, in part at least, of illustrating and supporting the same theoretical views; with these we have to deal in the next chapter. . dr. charles daubeny, f.r.s., _description of active and extinct volcanoes, of earthquakes, and of thermal springs, with remarks on the causes of these phenomena, the character of their respective products, and their influence on the past and present condition of the globe_ ( nd edition, ). in this work the author gives detailed descriptions of almost all the known volcanic districts of the globe, and defends what is called "the chemical theory of volcanic action"--a theory at one time held by sir humphrey davy. . wolfgang sartorius von waltershausen, _der Ætna_. this work possesses a melancholy interest from the fact that its distinguished author did not live to see its publication. von waltershausen, having spent several years in making an elaborate survey of etna, produced an atlas containing numerous detailed maps, views, and drawings of this mountain and its surroundings, which were published at weimar by engelmann in . a description in ms. to accompany the atlas was also prepared, but before it was printed, the author died, on the th october . the ms. having been put into the hands of the late professor arnold von lasaulx by the publisher of the atlas, it was subsequently brought out under the care of this distinguished petrologist, who was so fully fitted for an undertaking of this kind. . sir charles lyell in his _principles of geology_[ ] devotes several chapters to the consideration of volcanic phenomena, in which, being in harmony with the views of his friend, poulett scrope, he combats the "elevation theory" of von buch, as applied to the formation of volcanic mountains, holding that they are built up of ashes, stones, and scoriæ blown out of the throat of the volcano and piled around the orifice in a conical form. together with these materials are sheets of lava extruded in a molten condition from the sides or throat of the crater itself. . professor j. w. judd, f.r.s., in his able work entitled, _volcanoes: what they are, and what they teach_,[ ] has furnished the student of vulcanicity with a very complete manual of a general character on the subject. the author, having extensive personal acquaintance with the volcanoes of the south of europe and the volcanic rocks of the british isles, was well equipped for undertaking a work of the kind; and in it he supports the views of lyell and scrope regarding the mode of formation of volcanic mountains. . sir archibald geikie, f.r.s., in his elaborate monograph[ ] on the tertiary volcanic rocks of the british isles, has recorded his views regarding the origin and succession of the plateau basalts and associated rocks over the region extending from the north of ireland to the inner hebrides; and in dealing with these districts in the following pages i have made extensive use of his observations and conclusions. . _report published by the royal society on the eruption of krakatoa_--drawn up by several authors ( )--and the work on the same subject by chev. verbeek, and published by the government of the netherlands ( ). in these works all the phenomena connected with the extraordinary eruptions of krakatoa in are carefully noted and scientifically discussed, and illustrated by maps and drawings. . _the charleston earthquake of august , _, by captain clarence edward dutton, u.s. ordnance corps. ninth annual report of the united states geological survey, - , with maps and illustrations. . amongst other works which may be consulted with advantage is that of mr. t. mellard reade on _the origin of mountain ranges_; the rev. osmond fisher's _physics of the earth_; professor g. h. darwin and mr. c. davison on "the internal tension of the earth's crust," _philosophical transactions of the royal society_, vol. ; mr. r. mallet, "on the dynamics of earthquakes," _trans. roy. irish academy_, vol. xxi.; professor o'reilly's "catalogues of earthquakes," _trans. roy. irish academy_, vol. xxviii. ( and ); and mr. a. ent. gooch _on the causes of volcanic action_ (london, ). these and other authorities will be referred to in the text. [ ] see julius schwarez _on the failure of geological attempts made by the greeks_. (edition .) [ ] "vidi ego, quod fuerat quondam solidissima tellus, esse fretum. vidi factas ex æquore terras: et procul à pelago conchæ jacuere marinæ; et vetus inventa est in montibus anchora sumnis. quodque fuit campus, vallem de cursus aquarum fecit; et eluvie mons est deductus in æquor: eque paludosa siccis humus aret arenis; quæque sitim tulerant, stagnata paludibus hument. hic fontes natura novos emissit, at illuc clausit: et antiquis concussa tremoribus orbis fulmina prosiliunt...." --lib. xv. . [ ] "nec, quæ sulfureis ardet fornacibus, Ætne ignea semper erit; neque enim fuit ignea semper. nam, sive est animal tellus, et vivit, habetque spiramenta locis flammam exhalantia multis; spirandi mutare vias, quotiesque movetur, has finire potest, illas aperire cavernas: sive leves imis venti cohibentur in antris; saxaque cum saxis...." --_ibid._, . [ ] strabo, lib. vi. [ ] tacitus, lib. vi. , . [ ] _principles of geology_, th edition, vol. i., ch. . [ ] vols., edin. ( ). [ ] edin. ( ). [ ] a more extended list of early works will be found in daubeny's _volcanoes_ ( ). [ ] th edition ( ). [ ] th edition ( ). [ ] "the history of volcanic action during the tertiary period in the british isles," _trans. roy. soc., edin._ vol. xxxv, ( ). chapter ii. form, structure, and composition of volcanic mountains. the conical form of a volcanic mountain is so generally recognised, that many persons who have no intelligent acquaintance with geological phenomena are in the habit of attributing to all mountains having a conical form, and especially if accompanied by a truncated apex, a volcanic origin. yet this is very far from being the fact, as some varieties of rock, such as quartzite, not unfrequently assume this shape. of such we have an example in the case of errigal, a quartzite mountain in donegal, nearly feet high, which bears a very near approach in form to a perfect cone or pyramid, and yet is in no way connected, as regards its origin or structure, with volcanic phenomena. another remarkable instance is that of schehallion in scotland, also composed of quartz-rock; and others may be found amongst the ranges of islay and jura, described by sir a. geikie.[ ] notwithstanding, however, such exceptions, which might be greatly multiplied, the majority of cone-shaped mountains over the globe have a volcanic origin.[ ] the origin of this form in each case is entirely distinct. in the case of quartzite mountains, the conical form is due to atmospheric influences acting on a rock of uniform composition, traversed by numerous joints and fissures crossing each other at obtuse angles, along which the rock breaks up and falls away, so that the sides are always covered by angular shingle forming slopes corresponding to the angle of friction of the rock in question. in the case of a volcanic mountain, however, the same form is due either to accumulation of fragmental material piled around the cup-shaped hollow, or crater, which is usually placed at the apex of the cone, and owing to which it is bluntly terminated, or else to the welling up from beneath of viscous matter in the manner presently to be described. _views of sir humphrey davy and l. von buch._--the question how a volcanic cone came to be formed was not settled without a long controversy carried on by several naturalists of eminence. some of the earlier writers of modern times on the subject of vulcanicity--such as sir humphrey davy and leopold von buch--maintained that the conical form was due to upheaval by a force acting from below at a central focus, whereby the materials of which the mountain is formed were forced to assume a _quâ-quâ versal_ position--that is, a position in which the materials dip away from the central focus in every direction. but this view, originally contested by scrope and lyell, has now been generally abandoned. it will be seen on reflection that if a series of strata of ashes, tuff, and lava, originally horizontal, or nearly so, were to be forced upwards into a conical form by a central force, the result would be the formation of a series of radiating fissures ever widening from the circumference towards the focus. in the case of a large mountain such fissures, whether filled with lava or otherwise, would be of great breadth towards the focus, or central crater, and could not fail to make manifest beyond dispute their mechanical origin. but no fissures of the kind here referred to are, as a matter of fact, to be observed. those which do exist are too insignificant and too irregular in direction to be ascribed to such an origin; so that the views of von buch and davy must be dismissed, as being unsupported by observation, and as untenable on dynamical grounds. as a matter of fact, the "elevatory theory," or the "elevation-crater theory," as it is called by scrope, has been almost universally abandoned by writers on vulcanicity. _principal varieties of volcanic mountains as regards form._--but whilst rejecting the "elevatory theory," it is necessary to bear in mind that volcanic cones and dome-shaped elevations have been formed in several distinct ways, giving rise to varieties of structure essentially different. two of the more general of these varieties of form, the crater-cone and the dome, are found in some districts, as in auvergne, side by side. the crater-cone consists of beds or sheets of ashes, lapilli, and slag piled up in a conical form, with a central crater (or cup) containing the principal pipe through which these materials have been erupted; the dome, of a variety of trachytic lava, which has been extruded in a molten, or viscous, condition from a central pipe, and in such cases there is no distinct crater. there are other forms of volcanic mountains, such as those built up of basaltic matter, of which i shall have to speak hereafter, but the two former varieties are the most prevalent; and we may now proceed to consider the conditions under which the crater-cone volcanoes have been formed. _crateriform volcanic cones._--of this class nearly all the active volcanoes of the mediterranean region--etna, vesuvius, stromboli, and the lipari islands--may be considered as representatives. they consist essentially of masses of fragmental material, which have from time to time been blown out of an orifice and piled up around with more or less regularity (according to the force exerted, and direction of the prevalent winds), alternating with sheets of lava. in this way mountains several thousand feet in height and of vast horizontal extent are formed. the fragmental materials thus accumulated are of all sizes, from the finest dust up to blocks many tons in weight, the latter being naturally piled around nearest to the orifice. the fine dust, blown high into the air by the explosive force of the gases and vapours, is often carried to great distances by the prevalent winds. thus during the eruption of vesuvius in a.d. showers of ashes, carried high into the air by the westerly wind, fell over constantinople at a distance of miles.[ ] these loose, or partially consolidated, fragmental materials are rudely stratified, and slope downwards and outwards from the edge of the crater, so as to present the appearance of what is known as "the dip" of stratified deposits which have been upraised from the horizontal position by terrestrial forces. it was this excentrical arrangement which gave rise to the supposition that such volcanic ash-beds had been tilted up by a force acting in the direction of the volcanic throat, or orifice of eruption. the interior wall of monte di somma, the original crater of vesuvius, presents a good illustration of such fragmental beds. i shall have occasion further on to describe more fully the structure of this remarkable mountain; so that it will suffice to say here that this old prehistoric crater, the walls of which enclose the modern cone of vesuvius, is seen to be formed of irregular beds of ash, scoriæ, and fragmental masses, traversed by numerous dykes of lava, and sloping away outwards towards the surrounding plains. of similar materials are the flanks of etna composed, even at great distances from the central crater; the beds of ash and agglomerate sometimes alternating with sheets of solidified lava and traversed by dykes of similar material of later date, injected from below through fissures formed during periods of eruptive energy. numerous similar examples are to be observed in the auvergne region of central france and the eifel. and here we find remarkable cases of "breached cones," or craters, which will require some special description. standing on the summit of the puy de dôme, and looking northwards or southwards, the eye wanders over a tract formed of dome-shaped hills and of extinct crater-cones rising from a granitic platform. but what is most peculiar in the scene is the ruptured condition of a large number of the cones with craters. in such cases the wall of the crater has been broken down on one side, and we observe that a stream of lava has been poured out through the breach and overflowed the plain below. the cause of this breached form is sufficiently obvious. in such cases there has been an explosion of ashes, stones, and scoriæ from the volcanic throat, by which a cone-shaped hill with a crater has been built up. this has been followed by molten lava welling up through the throat, and gradually filling the crater. but, as the lava is much more dense than the material of which the crater wall is composed, the pressure of the lava outwards has become too great for the resistance of the wall, which consequently has given way at its weakest part and, a breach being formed, the molten matter has flowed out in a stream which has inundated the country lying at the base of the cone. in one instance mentioned by scrope, the original upper limit of the lake of molten lava has left its mark in the form of a ring of slag on the inside of the breached crater.[ ] _craterless domes._--these differ essentially both in form and composition from those just described, and have their typical representatives in the auvergne district, though not without their analogues elsewhere, as in the case of chimborazo, in south america, one of the loftiest volcanic mountains in the world. [illustration: fig. .--cotopaxi, a volcano of the cordilleras of quito, still active, and covered by snow down to a level of , feet. below this is a zone of naked rock, succeeded by another of forest vegetation. owing to the continuous extrusion of lava from the crater, the cone is being gradually built up of fresh material, and the crater is comparatively small in consequence.--(a diagrammatic view after a. von humboldt.)] taking the puy de dôme, petit suchet, cliersou, grand sarcoui in auvergne, and the mamelon in the isle of bourbon as illustrations, we have in all these cases a group of volcanic hills, dome-shaped and destitute of craters, the summits being rounded or slightly flattened. we also observe that the flanks rise more abruptly from their bases, and contrast in outline with the graceful curve of the crater cones. the dome-shaped volcanoes are generally composed of felsitic matter, whether domite, trachyte, or andesite, which has been extruded in a molten or viscous condition from some orifice or fissure in the earth's crust, and being piled up and spreading outwards, necessarily assumes such a form as that of a dome, as has been shown by experiment on a small scale by dr. e. reyer, of grätz.[ ] the contrast between the two forms (those of the dome and the crater-cone) is exemplified in the case of the grand sarcoui and its neighbours. the former is composed of a species of trachyte; the latter of ashes and fragmental matter which have been blown out of their respective vents of eruption into the air, and piled up and around in a crateriform manner with sides of gradually diminishing slope outwards, thus giving rise to the characteristic volcanic curve. the two varieties here referred to, contrasting in form, composition, and colour of material, can be clearly recognised from the summit of the puy de dôme, which rises by a head and shoulders above its fellows, and thus affords an advantageous standpoint from which to compare the various forms of this remarkable group of volcanic mountains. cotopaxi (fig. ) has been generally supposed to be a dome; but whymper, who ascended the mountain in , shows that it is a cone with a crater, , feet in largest diameter. he determined the height to be , feet above the ocean. its real elevation above the sea is somewhat masked, owing to the fact that it rises from the high plain of tapia, which is itself , feet above the sea surface. the smaller peak on the right (fig. ) is that of carihuairazo, which reaches an elevation of over , feet. chimborazo, in columbia, province of quito, is one of the loftiest of the chain of the andes, and is situated in lat. ° ' s., long. ° ' w. though not in a state of activity, it is wholly composed of volcanic material, and reaches an elevation of over , feet above the ocean; its sides being covered by a sheet of permanent snow to a level of , feet below the summit.[ ] seen from the shores of the pacific, after the long rains of winter, it presents a magnificent spectacle, "when the transparency of the air is increased, and its enormous circular summit is seen projected upon the deep azure blue of the equatorial sky. the great rarity of the air through which the tops of the andes are seen adds much to the splendour of the snow, and aids the magical effect of its reflection." chimborazo was ascended by humboldt and bonpland in almost to the summit; but at a height of , feet by barometrical measurement, their further ascent was arrested by a wide chasm. boussingault, in company with colonel hall, accomplished the ascent as far as the foot of the mass of columnar "trachyte," the upper surface of which, covered by a dome of snow, forms the summit of the mountain. the whole mass of the mountain consists of volcanic rock, varieties of andesite; there is no trace of a crater, nor of any fragmental materials, such as are usually ejected from a volcanic vent of eruption.[ ] _lava crater-cones._--a third form of volcanic mountain is that which has been built up by successive eruptions of basic lava, such as basalt or dolerite, when in a molten condition. these are very rare, and the slope of the sides depends on the amount of original viscosity. where the lava is highly fused its slope will be slight, but if in a viscous condition, successive outpourings from the orifice, unable to reach the base of the mountain, will tend to form a cone with increasing slope upwards. mauna loa and kilauea, in the hawaiian group, according to professor j. d. dana, are basalt volcanoes in a normal state. they have distinct craters, and the material of which the mountain is formed is basalt or dolerite. the volcano of rangitoto in auckland, new zealand, appears to belong to this class. basalt is the most fusible of volcanic rocks, owing to the augite and magnetite it contains, so that it spreads out with a very slight slope when highly fused. trachyte, on the other hand, is the least fusible owing to the presence of orthoclase felspar, or quartz; so that the volcanic domes formed of this material stand at a higher angle from the horizon than those of basaltic cones. [ ] _scenery and geology of scotland_ ( ), p. . [ ] humboldt says: "the form of isolated conical mountains, as those of vesuvius, etna, the peak of teneriffe, tunguagua, and cotopaxi, is certainly the shape most commonly observed in volcanoes all over the globe."--_views of nature_, translated by e. c. otté and h. g. bohn ( ). [ ] it is supposed that after the disastrous explosion of krakatoa in the fine dust carried into the higher regions of the atmosphere was carried round almost the entire globe, and remained suspended for a lengthened period, as described in a future page. [ ] another remarkable case is mentioned and figured by judd, where one of the lipari isles, composed of pumice and rising out of the mediterranean, has been breached by a lava-stream of obsidian.--_loc. cit._, p. . [ ] reyer has produced such dome-shaped masses by forcing a quantity of plaster of paris in a pasty condition up through an orifice in a board; referred to by judd, _loc. cit._, p. . [ ] whymper determined the height to be , feet; reiss and stübel make it , feet. whymper thinks there may be a crater concealed beneath the dome of snow.--_travels amongst the great andes of the equator_, by edward whymper ( ). [ ] whymper states that there is a prevalent idea that cotopaxi and a volcano called sangai act as safety-valves to each other. sangai reaches an elevation (according to reiss and stübel) of , feet, and sends intermittent jets of steam high into the air, spreading out into vast cumulus clouds, which float away southwards, and ultimately disappear.--_ibid._, p. . chapter iii. lines and groups of active volcanic vents. the globe is girdled by a chain of volcanic mountains in a state of greater or less activity, which may perhaps be considered a girdle of safety for the whole world, through which the masses of molten matter in a state of high pressure beneath the crust find a way of escape; and thus the structure of the globe is preserved from even greater convulsions than those which from time to time take place at various points on its surface. this girdle is partly terrestrial, partly submarine; and commencing at mount erebus, near the antarctic pole, ranging through south shetland isle, cape horn, the andes of south america, the isthmus of panama, then through central america and mexico, and the rocky mountains to kamtschatka, the aleutian islands, the kuriles, the japanese, the philippines, new guinea, and new zealand, reaches the antarctic circle by the balleny islands. this girdle sends off branches at several points. (see map, p. .) [illustration: fig. .--volcanic cone of orizaba (cittaltepeth), in mexico, now extinct; the upper part snow-clad, and at its base forest vegetation; it reaches a height of , parisian feet above the sea.--(after a. von humboldt.)] (_a._) the linear arrangement of active or dormant volcanic vents has been pointed out by humboldt, von buch, daubeny, and other writers. the great range of burning mountains of the andes of chili, peru, bolivia, and mexico, that of the aleutian islands, of kamtschatka and the kurile islands, extending southwards into the philippines, and the branching range of the sunda islands are well-known examples. that of the west indian islands, ranging from grenada through st. vincent, st. lucia, martinique, dominica, guadeloupe, montserrat, nevis, and st. eustace,[ ] is also a remarkable example of the linear arrangement of volcanic mountains. on tracing these ranges on a map of the world[ ] (map, p. ), it will be observed that they are either strings of islands, or lie in proximity to the ocean; and hence the view was naturally entertained by some writers that oceanic water, or at any rate that of a large lake or sea, was a necessary agent in the production of volcanic eruptions. this view seems to receive further corroboration from the fact that the interior portions of the continents and large islands such as australia are destitute of volcanoes in action, with the remarkable exceptions of mounts kenia and kilimanjaro in central africa, and a few others. it is also very significant in this connection that many of the volcanoes now extinct, or at least dormant, both in europe and asia, appear to have been in proximity to sheets of water during the period of activity. thus the old volcanoes of the haurân, east of the jordan, appear to have been active at the period when the present jordan valley was filled with water to such an extent as to constitute a lake two hundred miles in length, but which has now shrunk back to within the present limits of the dead sea.[ ] again, at the period when the extinct volcanoes of central france were in active operation, an extensive lake overspread the tract lying to the east of the granitic plateau on which the craters and domes are planted, now constituting the rich and fertile plain of clermont. [illustration: map of the world showing active and extinct volcanoes (large dots)] such instances are too significant to allow us to doubt that water in some form is very generally connected with volcanic operations; but it does not follow that it was necessary to the original formation of volcanic vents, whether linear or sporadic. if this were so, the extinct volcanoes of the british isles would still be active, as they are close to the sea-margin, and no volcano would now be active which is not near to some large sheet of water. but jorullo, one of the great active volcanoes of mexico, lies no less than miles from the ocean, and cotopaxi, in ecuador, is nearly equally distant. kilimanjaro, , feet high, and kenia, in the equatorial regions of central africa, are about miles from the victoria nyanza, and a still greater distance from the ocean; and mount demavend, in persia, which rises to an elevation of , feet near the southern shore of the caspian sea, a volcanic mountain of the first magnitude, is now extinct or dormant.[ ] such facts as these all tend to show that although water may be an accessory of volcanic eruptions, it is not in all cases essential; and we are obliged, therefore, to have recourse to some other theory of volcanic action differing from that which would attribute it to the access of water to highly heated or molten matter within the crust of the earth. (_b._) _leopold von buch on rents and fissures in the earth's crust._--the view of leopold von buch, who considered that the great lines of volcanic mountains above referred to rise along the borders of rents, or fissures, in the earth's crust, is one which is inherently probable, and is in keeping with observation. that the crust of the globe is to a remarkable extent fissured and torn in all directions is a phenomenon familiar to all field geologists. such rents and fissures are often accompanied by displacement of the strata, owing to which the crust has been vertically elevated on one side or lowered on the other, and such displacements (or "faults") sometimes amount to thousands of feet. it is only occasionally, however, that such fractures are accompanied by the extrusion of molten matter; and in the north of england and scotland dykes of igneous rock, such as basalt, which run across the country for many miles in nearly straight lines, often cut across the faults, and are only rarely coincident with them. nevertheless, it can scarcely be a question that the grand chain of volcanic mountains which stretches almost continuously along the andes of south america, and northwards through mexico, has been piled up along the line of a system of fissures in the fundamental rocks parallel to the coast, though not actually coincident therewith. (_c._) _the cordilleras of quito._--the structure and arrangement of the cordilleras of quito, for example, are eminently suggestive of arrangement along lines of fissure. as shown by alexander von humboldt,[ ] the volcanic mountains are disposed in two parallel chains, which run side by side for a distance of over miles northwards into the state of columbia, and enclose between them the high plains of quito and lacunga. along the eastern chain are the great cones of el altar, rising to an elevation of , feet above the ocean, and having an enormous crater apparently dormant or extinct, and covered with snow; then cotopaxi (fig. ), its sides covered with snow, and sending forth from its crater several columns of smoke; then guamani and cayambe ( , feet), huge truncated cones apparently extinct; these constitute the eastern chain of volcanic heights. the western chain contains even loftier mountains. here we find the gigantic chimborazo, an extinct volcano whose summit is white with snow; carihuairazo[ ] and illiniza, a lofty pointed peak like the matterhorn; corazon, a snow-clad dome, reaching a height of , feet; atacazo and pichincha, the latter an extinct volcano reaching an elevation of , feet; such is the western chain, remarkable for its straightness, the volcanic cones being planted in one grand procession from south to north. this rectilinear arrangement of the western chain, only a little less conspicuous in the eastern, is very suggestive of a line of fracture in the crust beneath. and when we contemplate the prodigious quantity of matter included within the limits of these colossal domes and their environments, all of which has been extruded from the internal reservoirs, we gain some idea of the manner in which the contracting crust disposes of the matter it can no longer contain.[ ] between the volcanoes of quito and those of peru there is an intervening space of fourteen degrees of latitude. this is occupied by the andes, regarding the structure of which we have not much information except that at this part of its course it is not volcanic. but from arequipa in peru (lat. ° s.), an active volcano, we find a new series of volcanic mountains continued southwards through tacora ( , feet), then further south the more or less active vents of sajama ( , feet), coquina, tutupaca, calama, atacama, toconado, and others, forming an almost continuous range with that part of the desert of atacama pertaining to chili. through this country we find the volcanic range appearing at intervals; and still more to the southwards it is doubtless connected with the volcanoes of patagonia, north of the magellan straits, and of tierra del fuego. mr. david forbes considers that this great range of volcanic mountains, lying nearly north and south, corresponds to a line of fracture lying somewhat to the east of the range.[ ] (_d._) _other volcanic chains._--a similar statement in all probability applies to the systems of volcanic mountains of the aleutian isles, kamtschatka, the kuriles, the philippines, and sunda isles. nor can it be reasonably doubted that the western american coast-line has to a great extent been determined, or marked out, by such lines of displacement; for, as darwin has shown, the whole western coast of south america, for a distance of between and miles south of the equator, has undergone an upward movement in very recent times--that is, within the period of living marine shells--during which period the volcanoes have been in activity.[ ] (_e._) _the kurile islands._--this chain may also be cited in evidence of volcanic action along fissure lines. it connects the volcanoes of kamtschatka with those of japan, and the linear arrangement is apparent. in the former peninsula erman counted no fewer than thirteen active volcanic mountains rising to heights of , to , feet above the sea.[ ] in the chain of the kuriles professor john milne counted fifty-two well-defined volcanoes, of which nine, perhaps more, are certainly active.[ ] they are not so high as those of kamtschatka; but, on the other hand, they rise from very deep oceanic waters, and have been probably built up from the sea bottom by successive eruptions of tuff, lava, and ash. according to the view of professor milne, the volcanoes of the kurile chain are fast becoming extinct. (_f._) _volcanic groups._--besides the volcanic vents arranged in lines, of which we have treated above, there are a large number, both active and extinct, which appear to be disposed in groups, or sporadically distributed, over various portions of the earth's surface. i say _appear to be_, because this sporadic distribution may really be resolvable (at least in some cases) into linear distribution for short distances. thus the neapolitan group, which might at first sight seem to be arranged round vesuvius as a centre, really resolves itself into a line of active and extinct vents of eruption, ranging across italy from the tyrrhenian sea to the adriatic, through ischia, procida, monte nuovo and the phlegræan fields, vesuvius, and mount vultur.[ ] again, the extinct volcanoes of central france, which appear to form an isolated group, indicate, when viewed in detail, a linear arrangement ranging from north to south.[ ] another region over which extinct craters are distributed lies along the banks of the rhine, above bonn and the moselle; a fourth in hungary; a fifth in asia minor and northern palestine; and a sixth in central asia around lake balkash. these are all continental, and the linear distribution is not apparent. [ ] for an interesting account of this range of volcanic islands see kingsley's _at last_. the grandest volcanic peak is that of guadeloupe, rising to a height of feet above the ocean, amidst a group of fourteen extinct craters. but the most active vent of the range is the souffrière of st. vincent. in the eruption of this mountain sent forth clouds of pumice, scoriæ and ashes, some of which were carried by an upper counter current to barbados, one hundred miles to the eastward, covering the surface with volcanic dust to a depth of several inches. [ ] an excellent, and perhaps the most recent, map of this kind is that given by professor prestwich in his _geology_, vol. i. p. . one on a larger scale is that by keith johnston in his _physical atlas_. [ ] _memoir on the physical geology and geography of arabia petræa, palestine_, etc., published for the committee of the palestine exploration fund ( ), p. , etc. [ ] this mountain was ascended in by mr. taylor thomson, who found the summit covered with sulphur, and from a cone fumes at a high temperature issued forth, but there was no eruption.--_journ. roy. geographical soc._, vol. viii. p. . [ ] humboldt, _atlas der kleineren schriften_ ( ). [ ] ascended by whymper june , . he found the elevation to be , feet. [ ] the arrangement of the volcanoes of peru and bolivia is also suggestive of a double line of fissure, while those of chili suggest one single line. the volcanoes of arequipa, in the southern part of peru, are dealt with by dr. f. h. hatch, in his inaugural dissertation, _ueber die gesteine der vulcan-gruppe von arequipa_ (wien, ). the volcanoes rise to great elevations, having their summits capped by snow. the volcano of charchani, lying to the north of arequipa, reaches an elevation of , parisian feet. that of pichupichu reaches a height of , par. feet. the central cone of misti has been variously estimated to range from , to , par. feet. the rocks of which the mountains are composed consist of varieties of andesite. [ ] d. forbes, "on the geology of bolivia and southern peru," _quarterly journal of the geological society_, vol. xvii. p. ( ). [ ] darwin, _structure and distribution of coral reefs_, second edition, p. . [ ] erman, _reise um die welt_. [ ] milne, "cruise amongst the kurile islands," _geol. mag._, new ser. (august ). [ ] see daubeny, _volcanoes_, map i. [ ] sir a. geikie has connected as a line of volcanic vents those of sicily, italy, central france, the n. e. of ireland, the inner hebrides and iceland, of which the central vents are extinct or dormant, the extremities active. chapter iv. mid-ocean volcanic islands. _oceanic islands._--by far the most extensive regions with sporadically distributed volcanic vents, both active and extinct, are those which are overspread by the waters of the ocean, where the vents emerge in the form of islands. these are to be found in all the great oceans, the atlantic, the pacific, and the indian; but are especially numerous over the central pacific region. as kotzebue and subsequently darwin have pointed out, all the islands of the pacific are either coral-reefs or of volcanic origin; and many of these rise from great depths; that is to say, from depths of to fathoms. it is unnecessary here to attempt to enumerate all these islands which rise in solitary grandeur from the surface of the ocean, and are the scenes of volcanic operations; a few may, however, be enumerated. [illustration: fig. .--the peak of teneriffe (pic de teyde) as seen from the ocean.--(from a photograph.)] (_a._) _iceland._--in the atlantic, iceland first claims notice, owing to the magnitude and number of its active vents and the variety of the accompanying phenomena, especially the geysers. as lyell has observed,[ ] with the exception of etna and vesuvius, the most complete chronological records of a series of eruptions in existence are those of iceland, which come down from the ninth century of our era, and which go to show that since the twelfth century there has never been an interval of more than forty years without either an eruption or a great earthquake. so intense is the volcanic energy in this island that some of the eruptions of hecla have lasted six years without cessation. earthquakes have often shaken the whole island at once, causing great changes in the interior, such as the sinking down of hills, the rending of mountains, the desertion by rivers of their channels, and the appearance of new lakes. new islands have often been thrown up near the coast, while others have disappeared. in the intervals between the eruptions, innumerable hot springs afford vent to the subterranean heat, and solfataras discharge copious streams of inflammable matter. the volcanoes in different parts of the island are observed, like those of the phlegræan fields, to be in activity by turns, one vent serving for a time as a safety-valve for the others. the most memorable eruption of recent years was that of skaptár jokul in , when a new island was thrown up, and two torrents of lava issued forth, one and the other miles in length, and which, according to the estimate of professor bischoff, contained matter surpassing in magnitude the bulk of mont blanc. one of these streams filled up a large lake, and, entering the channel of the skaptâ, completely dried up the river. the volcanoes of iceland may be considered as safety-valves to the region in which lie the british isles. (_b._) _the azores, canary, and cape de verde groups._--this group of volcanic isles rises from deep atlantic waters north of the equator, and the vents of eruption are partially active, partially dormant, or extinct. it must be supposed, however, that at a former period volcanic action was vastly more energetic than at present; for, except at the grand canary, gomera, forta ventura, and lancerote, where various non-volcanic rocks are found, these islands appear to have been built up from their foundations of eruptive materials. the highest point in the azores is the peak of pico, which rises to a height of feet above the ocean. but this great elevation is surpassed by that of the peak of teneriffe (or pic de teyde) in the canaries, which attains to an elevation of , feet, as determined by professor piazzi smyth.[ ] this great volcanic cone, rising from the ocean, its summit shrouded in snow, and often protruding above the clouds, must be an object of uncommon beauty and interest when seen from the deck of a ship. (fig. .) the central cone, formed of trachyte, pumice, obsidian, and ashes, rises out of a vast caldron of older basaltic rocks with precipitous inner walls--much as the cone of vesuvius rises from within the partially encircling walls of somma. (fig. .) from the summit issue forth sulphurous vapours, but no flame. piazzi smyth, who during a prolonged visit to this mountain in made a careful survey of its form and structure, shows that the great cone is surrounded by an outer ring of basalt enclosing two _foci_ of eruption, the lavas from which have broken through the ring of the outer crater on the western side, and have poured down the mountain. at the top of the peak its once active crater is filled up, and we find a convex surface ("the plain of rambleta") surmounted towards its eastern end by a diminutive cone, feet high, called "humboldt's ash cone." the slope of the great cone of teneriffe ranges from ° to °; and below a level of feet the general slope of the whole mountain down to the water's edge varies from ° to ° from the horizontal. the great cone is penetrated by numerous basaltic dykes. the cape de verde islands, which contain beds of limestone along with volcanic matter, possess in the island of fuego an active volcano, rising to a height of feet above the surface of the ocean. the central cone, like that of teneriffe, rises from within an outer crater, formed of basalt alternating with beds of agglomerate, and traversed by numerous dykes of lava. this has been broken down on one side like that of somma; and over its flanks are scattered numerous cones of scoriæ, the most recent dating from the years and .[ ] [illustration: fig. .--view of the summit of the peak of teneriffe ( , feet) and of the secondary crater, or outer ring of basaltic sheets which surrounds its base; seen from the east.--(after leopold von buch.)] the volcanoes of lancerote have a remarkably linear arrangement from west to east across the island. they are not yet extinct; for an eruption in destroyed a large number of villages, and covered with lava the most fertile tracts in the island, which at the time of leopold von buch's visit lay waste and destitute of herbage.[ ] in the island of palma there is one large central crater, the caldera de palma, three leagues in diameter, the walls of which conform closely to the margin of the coast. von buch calls this crater "une merveille de la nature," for it distinguishes this isle from all the others, and renders it one of the most interesting and remarkable amongst the volcanic islands of the ocean. the outer walls are formed of basaltic sheets, and towards the south this great natural theatre is connected with the ocean by a long straight valley, called the "barranco de los dolores," along whose sides the structure of the mountain is deeply laid open to view. the outer flanks of the crater are furrowed by a great number of smaller barrancos radiating outward from the rim of the caldera. von buch regards the barrancos as having been formed during the upheaval of the island, according to his theory of the formation of such mountains (the elevation-theory); but unfortunately for his views, these ravines widen outwards from the centre, or at least do not become narrower in that direction, as would be the case were the elevation-theory sound. the maps which accompany von buch's work are remarkably good, and were partly constructed by himself. (_c._) _volcanic islands in the atlantic south of the equator._--the island of ascension, formed entirely of volcanic matter, rises from a depth of fathoms in the very centre of the atlantic. as described by darwin, the central and more elevated portions are formed of trachytic matter, with obsidian and laminated ash beds. amongst these are found ejected masses of unchanged granite, fragments of which have been torn from the central pipe during periods of activity, and would seem to indicate a granitic floor, or at least an original floor upon which more recent deposits may have been superimposed. in st. helena we seem, according to daubeny, to have the mere wreck of one great crater, no one stream of lava being traceable to its source, while dykes of lava are scattered in profusion throughout the whole substance of the basaltic masses which compose the island. tristan da cunha, in the centre of the south atlantic, rises abruptly from a depth of , feet, at a distance of miles from any land; and one of its summits reaches an elevation of feet, being a truncated cone composed of alternating strata of tuff and augitic lava, surrounding a crater in which is a lake of pure water. the volcano is extinct or dormant. were the waters of the ocean to be drawn off, these volcanic islands would appear like stupendous conical mountains, far loftier, and with sides more precipitous, than any to be found on our continental lands, all of which rise from platforms of considerable elevation. the enormous pressure of the water on their sides enables these mid-oceanic islands to stand with slopes varying from the perpendicular to a smaller extent than if they were sub-aerial; and it is on this account that we find them rising with such extraordinary abruptness from the "vasty deep." (_d._) _volcanic islands of the pacific._--the volcanic islands of this great ocean are scattered over a wide tract on both sides of the equator. those to the north of this line include the sandwich islands, the mariana or ladrone islands, south island, and bonin sima; south of the equator, the galapagos, new britain, salomon, santa cruz, new hebrides, the friendly and society isles. while the coral reefs and islands of the pacific may be recognised by their slight elevation above the surface of the waters, those of volcanic origin and containing active or extinct craters of eruption generally rise into lofty elevations, so that the two kinds are called the _low_ islands and _high_ islands respectively. amongst the group are trachytic domes such as the mountain of tobreonu in the society islands, rising to a height probably not inferior to that of etna, with extremely steep sides, and holding a lake on its summit.[ ] the linear arrangement of some of the volcanic islands of the pacific is illustrated by those of the tonga, or friendly, group, lying to the north of new zealand. they consist of three divisions--( ) the volcanic; ( ) those formed of stratified volcanic tuff, sometimes entirely or partially covered by coralline limestone; and ( ) those which are purely coralline. the first form a chain of lofty cones and craters, lying in a e.n.e. and w.s.w. direction, and rising from depths of over fathoms. mr. j. j. lister, who has described the physical characters of these islands, has shown very clearly that they lie along a line--probably that of a great fissure--stretching from the volcanic island of amargura on the north (lat. ° s.), through lette, metis, kao ( feet), tofua, falcon, honga tonga, and the kermadec group into the new zealand chain on the south. some of these volcanoes are in a state of intermittent activity, as in the case of tofua (lat. ° ' s.), metis island, and amargura; the others are dormant or extinct. the whole group appears to have been elevated at a recent period, as some of the beds of coral have been raised feet and upward above the sea-level, as in the case of eua island.[ ] the greater number of the pacific volcanoes appear to be basaltic; such as those of the hawaiian group, which have been so fully described by professor j. d. dana.[ ] here fifteen volcanoes of the first class have been in brilliant action; all of which, except three, are now extinct, and these are in hawaii the largest and most eastern of the group. this island contains five volcanic mountains, of which kea, , feet, is the highest; next to that, loa, , feet; after these, hualalai, rising feet; kilauea, feet; and kohala, feet above the sea; this last is largely buried beneath the lavas of mauna kea. the group contains a double line of volcanoes, one lying to the north and west of the other; and as the highest of the hawaiian group rises from a depth in the ocean of over fathoms, the total elevation of this mountain from its base on the bed of the ocean is not far from , feet, an elevation about that of the himalayas. mauna kea has long been extinct, hualalai has been dormant since ; but mauna loa is terribly active, there having been several eruptions, accompanied by earthquakes, within recent years, the most memorable being those of and . in the former case the lava rose from the deep crater into "a lofty mountain," as described by mr. coan,[ ] and then flowed away eastward for a distance of twenty miles. the interior of the crater consists of a vast caldron, surrounded by a precipice to feet in depth, with a circumference of about fifteen miles, and containing within it a second crater, bounded by a black ledge with a steep wall of basalt--a crater within a crater; and from the floor of the inner crater, formed of molten basalt, in a seething and boiling state, arise a large number of small cones and pyramids of lava, some emitting columns of grey smoke, others brilliant flames and streams of molten lava, presenting a wonderful spectacle, the effect of which is heightened by the constant roaring of the vast furnaces below.[ ] [ ] _principles of geology_, th edition, vol. ii. p. . [ ] smyth, _report on the teneriffe astronomical experiment of _. humboldt makes the elevation , feet. a beautiful model of the peak was constructed by mr. j. nasmyth from piazzi smyth's plans, of which photographs are given by the latter. [ ] daubeny, _loc. cit._, p. . [ ] _iles canaries_, p. . [ ] daubeny, _loc. cit._, p. . [ ] lister, "notes on the geology of the tonga islands," _quart. jour. geol. soc._, no. , p. ( ). [ ] dana, _characteristics of volcanoes, with contributions of facts and principles from the hawaiian islands_. london, .--also, _geology of the american exploring expedition--volcanoes of the sandwich islands_. [ ] coan, _amer. jour. of science_, . [ ] w. ellis, the missionary, has given a vivid description of this volcano in his _tour of hawaii_. london, .--plans of the crater will be found in professor dana's work above quoted. part ii. european volcanoes. chapter i. vesuvius. having now dealt in a necessarily cursory manner with volcanoes of distant parts of the globe, we may proceed to the consideration of the group of active volcanoes which still survive in europe, as they possess a special interest, not only from their proximity and facility of access, at least to residents in europe and the british isles, but from their historic incidents; and in this respect vesuvius, though not by any means the largest of the group, stands the first, and demands more special notice. the whole group rises from the shores of the mediterranean, and consists of vesuvius, etna, stromboli, one of the lipari islands, and vulcano, a mountain which has given the name to all mountains of similar origin with itself.[ ] along with these are innumerable cones and craters of extinct or dormant volcanoes, of which a large number have been thrown out on the flanks of etna. (_a._) _prehistoric ideas regarding the nature of this mountain._--down to the commencement of the christian era this mountain had given no ostensible indication that it contained within itself a powerful focus of volcanic energy. true, that some vague tradition that the mountain once gave forth fire hovered around its borders; and several ancient writers, amongst them diodorus siculus and strabo, inferred from the appearances of the higher parts of the mountain and the character of the rocks, which were "cindery and as if eaten by fire," that the country was once in a burning state, "being full of fiery abysses, though now extinct from want of fuel." seneca (b.c. to a.d. ) had detected the true character of vesuvius, as "having been a channel for the internal fire, but not its food;" nevertheless, at this period the flanks of the mountain were covered by fields and vineyards, while the summit, partially enclosed with precipitous walls of the long extinct volcano, somma, was formed of slaggy and scoriaceous material, with probably a covering of scrub. here it was that the gladiator spartacus (b.c. ), stung by the intolerable evils of the roman government, retreated to the very summit of the mountain with some trusty followers. clodius the prætor, according to the narration of plutarch, with a party of three thousand men, was sent against them, and besieged them in a mountain (meaning vesuvius or somma) having but one narrow and difficult passage, which clodius kept guarded; all the rest was encompassed with broken and slippery precipices, but upon the top grew a great many wild vines; the besieged cut down as many as they had need of, and twisted them into ladders long enough to reach from thence to the bottom, by which, without any danger, all got down except one, who stayed behind to throw them their arms, after which he saved himself with the rest.[ ] "on the top" must (as professor phillips observes) be interpreted the summit of the exterior slope or crater edge, which would appear from the narrative to have broken down on one side, affording an entrance and mode of egress by which spartacus fell upon, and surprised, the negligent clodius glabrus. [illustration: fig. .--probable aspect of vesuvius as it appeared at the beginning of the christian era; seen from the bay of naples.] in fancied security, villas, temples, and cities had been erected on the slopes of the mountain. herculaneum, pompeii, and stabiæ, the abodes of art, luxury, and vice, had sprung up in happy ignorance that they "stood on a volcano," and that their prosperity was to have a sudden and disastrous close.[ ] (_b._) _premonitory earthquake shocks._--the first monitions of the impending catastrophe occurred in the rd year after christ, when the whole campagna was shaken by an earthquake, which did much damage to the towns and villas surrounding the mountain even beyond naples. this was followed by other shocks; and in pompeii the temple of isis was so much damaged as to require reconstruction, which was undertaken and carried out by a citizen at his own expense.[ ] these earthquake shakings continued for sixteen years. at length, on the night of august th, a.d. , they became so violent that the whole region seemed to reel and totter, and all things appeared to be threatened with destruction. the next day, about one in the afternoon, there was seen to rise in the direction of vesuvius a dense cloud, which, after ascending from the summit of the mountain into the air for a certain height in one narrow, vertical trunk, spread itself out laterally in such a form that the upper part might be compared to the cluster of branches, and the lower to the stem of the pine which forms so common a feature in the italian landscape.[ ] (_c._) _pliny's letters to tacitus._--for an account of what followed we are indebted to the admirable letters of the younger pliny, addressed to the historian tacitus, recounting the events which caused, or accompanied, the death of his uncle, the elder pliny, who at the time of this first eruption of vesuvius was in command of the roman fleet at the entrance to the bay of naples. these letters, which are models of style and of accurate description, are too long to be inserted here; but he recounts how the dense cloud which hung over the mountain spread over the whole surrounding region, sometimes illuminated by flashes of light more vivid than lightning; how showers of cinders, stones, and ashes fell in such quantity that his uncle had to flee from stabiæ, and that even at so great a distance as misenum they encumbered the surface of the ground; how the ground heaved and the bed of the sea was upraised; how the cloud descended on misenum, and even the island of capreæ was concealed from view; and finally, how, urged by a friend who had arrived from spain, he, with filial affection, supported the steps of his mother in flying from the city of destruction. such being the condition of the atmosphere and the effects of the eruption at a point so distant as cape misenum, some sixteen geographical miles from the focus of eruption, it is only to be expected that places not half the distance, such as herculaneum, pompeii, and even stabiæ, with many villages and dwellings, should have shared a worse fate. the first of these cities, situated on the coast of the bay of naples, appears to have been overwhelmed by volcanic mud; pompeii was buried in ashes and lapilli, and stabiæ probably shared a similar fate.[ ] (_d._) _appearance of the mountain at the commencement of the christian era._--at the time of the first recorded eruption vesuvius appears to have consisted of only a single cone with a crater, now known as monte di somma, the central cone of eruption which now rises from within this outer ruptured casing not having been formed. (fig. .) the first effect of the eruption of the year was to blow out the solidified covering of slag and scoriæ forming the floor of the caldron. doubtless at the close of the eruption a cone of fragmental matter and lava of some slight elevation was built up, and, if so, was subsequently destroyed; for, as we shall presently see by the testimony of the abate guilio cesare braccini, who examined the mountain not long before the great eruption of a.d. , there was no central cone to the mountain at that time; and the mountain had assumed pretty much the appearance it had at the time that spartacus took refuge within the walls of the great crater. (_e._) _destruction of pompeii._--pompeii was overwhelmed with dry ashes and lapilli. sir w. hamilton found some of the stones to weigh eight pounds. at the time of the author's visit, early in april , the excavations had laid open a section about ten feet deep, chiefly composed of alternating layers of small pumice stones (lapilli) and volcanic dust. it was during the sinking of a well in upon the theatre containing the statues of hercules and cleopatra that the existence of the ancient city was accidentally discovered. (_f._) _more recent eruptions._--since the first recorded eruption in a.d. down to the present day, vesuvius has been the scene of numerous intermittent eruptions, of which some have been recorded; but many, doubtless, are forgotten. in a.d. , during the reign of severus, an eruption of extraordinary violence took place, which is related by dion cassius, from whose narrative we may gather that at this time there was only one large crater, and that the central cone of vesuvius had not as yet been upraised. in a.d. an eruption occurred of such magnitude as to cover all europe with fine dust, and spread alarm even at constantinople. (_g._) _eruption of ._--in december occurred the great convulsion whose memorials are written widely on the western face of vesuvius in ruined villages. this eruption left layers of ashes over hundreds of miles of country, or heaps of mud swept down by hot water floods from the crater; the crater itself having been dissipated in the convulsion. braccini, who examined the mountain not long before this eruption, found apparently no cone (or mount) like that of the modern vesuvius. he states that the crater was five miles in circumference, about a thousand paces deep (or in sloping descent), and its sides covered with forest trees and brushwood, while at the bottom there was a plain on which cattle grazed.[ ] it would seem that the mountain had at this time enjoyed a long interval of rest, and that it had reverted to very much the same state in which it was at the period of the first eruption, when the flanks were peopled by inhabitants living in fancied security. but six months of violent earthquakes, which grew more violent towards the close of , heralded the eruption which took place in december, accompanied by terrific noises from within the interior of the mountain. the inhabitants of the coast were thus warned of the approaching danger, and had several days to arrange for their safety; but in the end, a great part of torre del greco was destroyed, and a like fate overtook resina and granatello, with a loss of life reported at , persons. during the eruption clouds condensed into tempests of rain, and hot water from the mountain, forming deluges of mud, swept down the sides, and reached even to nola and the apennines. nor was the sea unmoved. it retired during the violent earthquakes, and then returned full thirty paces beyond its former limits. not indeed until near the close of the seventeenth century is there any evidence that the central cone of vesuvius was in existence; but in october an eruption occurred which is recorded by sorrentino, during which was erected "a new mountain within, and higher than the old one, and visible from naples," a statement evidently referable to the existing cone--so that it is little more than two centuries since this famous volcanic mountain assumed its present form. (_h._) _eruptions between the years and ._--since a.d. there have been fifty-six recorded eruptions of vesuvius; one of these in was of terrific violence and destructiveness, and is represented by sir william hamilton in views taken both before and during the eruption. a pen-and-ink drawing of the appearance of the crater before the eruption is here reproduced from hamilton's picture, from which it will be seen that the central crater contained within itself a second crater-cone, from whence steam, lava, and stones were being erupted (fig. ). thus it will be seen that vesuvius at this epoch consisted of three crater-cones within each other. the first, monte di somma; the second, the cone of vesuvius; and the third, the little crater-cone within the second. during this eruption, vast lava-sheets invaded the fields and vineyards on the flanks of the mountain. a vivid account of this eruption, as witnessed by padre torre, is given by professor phillips.[ ] we shall pass over others without further reference until we come down to our own times, in which vesuvius has resumed its old character, and in one grand exhibition of volcanic energy, which took place in , has evinced to the world that it still contains within its deep-seated laboratory all the elements of destructive force which it exhibited at the commencement of our era. [illustration: fig. .--view of the crater of vesuvius before the eruption of , showing an interior crater-cone rising from the centre of the exterior crater.--(after sir w. hamilton.)] (_i._) _structure of the neapolitan campagna._--but before giving a description of this terrific outburst of volcanic energy, it may be desirable to give some account of the physical position and structure of this mountain, by which the phenomena of the eruption will be better understood. vesuvius and the neapolitan campagna are formed of volcanic materials bounded on the west by the gulf of naples, and on the east and south by ranges of jurassic limestone, a prolongation of the apennines, which send out a spur bounding the bay on the south, and forming the promontory of sorrento. the little island of capri is also formed of limestone, and is dissevered from the promontory by a narrow channel. the northern side of the bay is, however, formed of volcanic materials; it includes the phlegræan fields (campi phlegræi), and terminates in the promontory of miseno. lying in the same direction are the islands of procida and ischia, also volcanic. hence it will be seen that the two horns of the bay are formed of entirely different materials, that of miseno on the north being volcanic, that of sorrento on the south being composed of jurassic limestone, of an age vastly more ancient than the volcanic rocks on the opposite shore. (map, p. .) the general composition of the neapolitan campagna, from which the mountain rises, has been revealed by means of the artesian well sunk to a depth of about metres ( feet) at the royal palace of naples, and may be generalised as follows:-- { recent beds of volcanic tuff ( ) from surface to depth of { with marine shells, and containing feet { fragments of trachytic { lava, etc. (_volcanic beds_). { bituminous sands and marls ( ) from to { with marine shells of recent { species(?) (_pre-volcanic beds_). ( ) from to { eocene beds. micaceous sandstone { and marl (_macigno_). ( ) from to bottom { jurassic beds. apennine { limestone. [illustration: fig. .--map of the district bordering the bay of naples, with the islands of capri, ischia, and procida.] from the above section, for which we are indebted to mr. johnston-lavis, the most recent writer on vesuvius, it would appear that the first volcanic explosions by which the mountain was ultimately to be built up took place after the deposition of the sands and marls (no. ), while the whole campagna was submerged under the waters of the mediterranean. by the accumulation of the stratified tuff (no. ), the sea-bed was gradually filled up during a period of volcanic activity, and afterwards elevated into dry land.[ ] [illustration: fig. .--view of vesuvius from the harbour of naples at the commencement of the eruption of .--(from a sketch by the author.)] (_j._) _present form and structure of vesuvius and somma._--the outer cone of vesuvius, or monte di somma, rises from a circular platform by a moderately gentle ascent, and along the north and east terminates in a craggy crest, with a precipitous cliff descending into the atria del cavallo, forming the wall of the ancient crater throughout half its circumference; this wall is formed of scoriæ, ashes, and lapilli, and is traversed by numerous dykes of lava. along the west and south this old crater has been broken down; but near the centre there remains a round-backed ridge of similar materials, once doubtless a part of the original crater of somma, rising above the slopes of lava on either hand. on this has been erected the royal observatory, under the superintendence of professor luigi palmieri, where continuous observations are being made, by means of delicate seismometers, of the earth-tremors which precede or accompany eruptions; for it is only justice to say that vesuvius gives fair warning of impending mischief, and the instruments are quick to notify any premonitory symptoms of a coming catastrophe. the elevation of the observatory is feet above the sea. on either side of the observatory ridge are wide channels filled to a certain height with lavas of the nineteenth and preceding centuries, the most recent presenting an aspect which can only be compared to a confused multitude of black serpents and pachyderms writhing and interlocked in some frightful death-struggle. some of this lava, ten years old, as we cross its rugged and black surface presents gaping fissures, showing the mass to be red-hot a few feet from the surface, so slow is the process of cooling. these lava-streams--some of them reaching to the sea-coast--have issued forth from the atria at successive periods of eruption. from the midst of the atria rises the central cone, formed of cinders, scoriæ, and lava-streams, and fissured along lines radiating from the axis. this cone is very steep, the angle being about °- ° from the horizontal, and is formed of loose cindery matter which gives way at every step, and is rather difficult to climb. but on reaching the summit we look down into the crater, displaying a scene of ever-varying characters, rather oval in form, and about yards in diameter. from the map of professor guiscardi, published in , there are seen two minor craters within the central one, formed in , and an outflow of lava from the n.w. down the cone. at the time of the author's visit the crater was giving indications, by the great quantity of sulphurous gas and vapour rising from its surface, and small jets of molten lava beginning to flow down the outer side, of the grand outburst of internal forces which was presently to follow. (_k._) _eruption of ._--the grand eruption of , of which a detailed account is given by professor palmieri,[ ] commenced with a slight discharge of incandescent projectiles from the crater; and on the th january an aperture appeared on the upper edge of the cone from which at first a little lava issued forth, followed by the uprising of a cone which threw out projectiles accompanied by smoke, whilst the central crater continued to detonate more loudly and frequently. this little cone ultimately increased in size, until in april it filled the whole crater and rose four or five metres above the brim. at this time abundant lavas poured down from the base of the cone into the atria del cavallo, thence turned into the fossa della vetraria in the direction of the observatory and towards the crocella, where they accumulated to such an extent as to cover the hillside for a distance of about metres; then turning below the canteroni, formed a hillock without spreading much farther. in october another small crater was formed by the falling in of the lava, which after a few days gave vent to smoke and several jets of lava; and towards the end of october the detonations increased, the smoke from the central crater issued forth more densely mixed with ashes, and the seismographical apparatus was much disturbed. on the rd and th november copious and splendid lava-streams coursed down the principal cone on its western side, but were soon exhausted; and in the beginning of the little cone, regaining vigour, began to discharge lava from the summit instead of the base as heretofore. in the month of march , with the full moon, the cone opened on the north-west side--the cleavage being indicated by a line of fumaroles--and lava issued from the base and poured down into the atria as far as the precipices of monte di somma. on the rd april (another full moon) the activity of the craters increased, and on the evening of the th splendid lava-streams descended the cone in various directions, attracting on the same night the visits of a great many strangers. a lamentable event followed on the th. a party of visitors, accompanied by inexperienced guides, and contrary to the advice of professor palmieri, insisted on ascending to the place from which the lava issued. at half-past three on the morning of the th they were in the atria del cavallo, when the vesuvian cone was rent in a north-west direction and a copious torrent of lava issued forth. two large craters formed at the summit of the mountain, discharging incandescent projectiles and ashes. a cloud of smoke enveloped the unhappy visitors, who were under a hail-storm of burning projectiles. eight were buried beneath it, or in the lava, while eleven were grievously injured.[ ] the lava-stream, flowing over that of in the atria, divided into two branches, the smaller one flowing towards resina, but stopping before reaching the town; the larger precipitated itself into the fossa della vetraria, occupying the whole width of metres, and traversing the entire length of metres in three hours. it dashed into the fossa di farone, and reached the villages of massa and st. sebastiano, covering a portion of the houses, and, continuing its course through an artificial foss, or trench, invaded cultivated ground and several villages. if it had not greatly slackened after midnight, from failure of supply at its source, it would have reached naples by ponticelli and flowed into the sea. the eruption towards the end of april had reached its height. the observatory ridge was bounded on either side by two fiery streams, which rendered the heat intolerable. simultaneously with the opening of the great fissure two large craters opened at the summit, discharging with a dreadful noise an immense cloud of smoke and ashes, with bombs which rose to a height of metres above the brim of the volcano.[ ] the torrents of fire which threatened resina, bosco, and torre annunziata, and which devastated the fertile country of novelle, massa, st. sebastiano, and cerole, and two partially buried cities, the continual thunderings and growling of the craters, caused such terror, that numbers abandoned their dwellings, flying for refuge into naples, while many neapolitans went to rome or other places. fortunately, the paroxysm had now passed, the lava-streams stopped in their course, and the great torrent which passed the shoulders of the observatory through the fossa della vetraria lowered the level of its surface below that of its sides, which appeared like two parallel ramparts above it. had these streams continued to flow on the th of april as they had done on the previous night, they would have reached the sea, bringing destruction to the very walls of naples. during this eruption torre del greco was upraised to the extent of two metres, and nearly all the houses were knocked down. the igneous period of eruption having terminated, the ashes, lapilli, and projectiles became more abundant, accompanied by thunder and lightning. on the th they darkened the air, and the terrific noise of the mountain continuing or increasing, the terror at resina, portici, and naples became universal. it seemed as though the tragic calamities of the eruption of a.d. were about to be repeated. but gradually the force of the explosions decreased, and the noise from the crater became discontinuous, so that on the th the detonations were very few, and by the st may the eruption was completely over. such is a condensed account of one of the most formidable eruptions of our era. in the frontispiece of this volume a representation, taken (by permission) from a photograph by negretti & zambra, is given, showing the appearance of vesuvius during the final stage of the eruption, when prodigious masses of smoke, steam, and illuminated gas issued forth from the summit and overspread the whole country around with a canopy which the light of the sun could scarcely penetrate. it will be noticed in the above account that, concurrently with the full moon, there were two distinct and special outbreaks of activity; one occurring in march, the other in the month following. that the conditions of lunar and solar attraction should have a marked effect on a part of the earth's crust, while under the tension of eruptive forces, is only what might be expected. at full moon the earth is between the sun and the moon, and at new moon the moon is between the sun and the earth; under these conditions (the two bodies acting in concert) we have spring tides in the ocean, and a maximum of attraction on the mass of the earth. hence the crust, which at the time referred to was under tremendous strain, only required the addition of that caused by the lunar and solar attractions to produce rupture in both cases, giving rise to increased activity, and the extrusion of lava and volatile matter. it may, in general, be safely affirmed that low barometric pressure on the one hand, and the occurrence of the syzygies (when the attractions of the sun and moon are in the same line) on the other, have had great influence in determining the crises of eruptions of volcanic mountains when in a state of unrest. _contrast between the northern and southern slopes._--before leaving vesuvius it may be observed that throughout all the eruptions of modern times the northern side of the mountain, that is the old crater and flank of somma, has been secure from the lava-flows, and has enjoyed an immunity which does not belong to the southern and western side. if we look at a map of the mountain showing the direction of the streams during the last three centuries,[ ] we observe that all the streams of that period flowed down on the side overlooking the bay of naples; on the opposite side the wall of monte di somma presents an unbroken front to the lava-streams. from this it may be inferred that one side, the west, is weaker than the other; and consequently, when the lava and vapours are being forced upwards, under enormous pressure from beneath, the western side gives way under the strain, as in the case of the fissure of , and the lava and vapours find means of escape. from what has happened in the past it is clear that no place on the western side of the mountain is entirely safe from devastation by floods of lava; while the prevalent winds tend to carry the ashes and lapilli, which are hurled into the air, in the same westerly direction. [ ] for an excellent view of this remarkable volcanic group see judd's _volcanoes_, th edition, p. . [ ] plutarch, _life of cassius_; _ed. reiske_, vol. iii. p. . [ ] strabo gives the following account of the appearance and condition of vesuvius in his day:--"supra hæc loca situs est vesuvius mons, agris cinctus optimis; dempto vertice, qui magna sui parte planus, totus sterilis est, adspectu sinereus, cavernasque ostendens fistularum plenas et lapidum colore fuliginoso, utpote ab igni exesorum. ut conjectarum facere possis, ista loca quondam arsisse et crateras ignis habuisse, deinde materia deficiente restricta fuisse."--_rer. geog._, lib. v. [ ] a tablet over the entrance records this act of pious liberality, and is given by phillips, _loc. cit._, p. . [ ] the stone pine, _pinus pinea_, which turner knew how to use with so much effect in his italian landscapes. [ ] bulwer lytton's _last days of pompeii_ presents to the reader a graphic picture of the terrible event here referred to:--"the eyes of the crowd followed the gesture of the egyptian, and beheld with ineffable dismay a vast vapour shooting from the summit of vesuvius, in the form of a gigantic pine tree; the trunk--blackness, the branches--fire! a fire that shifted and wavered in its hues with every moment--now fiercely luminous, now of a dull and dying red that again blazed terrifically forth with intolerable glare!... then there arose on high the shrieks of women; the men stared at each other, but were speechless. at that moment they felt the earth shake beneath their feet; the walls of the theatre trembled; and beyond, in the distance, they heard the crash of falling roofs; an instant more and the mountain-cloud seemed to roll towards them, dark and rapid; at the same time it cast forth from its bosom a shower of ashes mixed with vast fragments of burning stone. over the crushing vines--over the desolate streets--over the amphitheatre itself--far and wide, with many a mighty splash in the agitated sea, fell that awful shower." a visit to the disinterred city will probably produce on the mind a still more lasting and vivid impression of the swift destruction which overtook this city. [ ] quoted by phillips, _loc. cit._, p. . [ ] _vesuvius_, p. _et seq._ [ ] johnston-lavis, "on the geology of monti somma and vesuvius," _quart. jour. geol. soc._, vol. ( ). [ ] palmieri, _eruption of vesuvius in _, with notes, etc., by robert mallet, f.r.s. london, . [ ] those who lost their lives were medical students, and an assistant professor in the university, antonio giannone by name. [ ] involving, as mr. mallet calculates, an initial velocity of projection of above feet per second. [ ] such as that given by professor phillips in his _vesuvius_. chapter ii. etna. (_a._) _structure of the mountain._--etna, unlike vesuvius, has ever been a burning mountain; hence it was well known as such to classic writers before the christian era. the structure and features of this magnificent mountain have been abundantly illustrated by elie de beaumont,[ ] daubeny,[ ] baron von waltershausen,[ ] and lyell,[ ] of whose writings i shall freely avail myself in the following account, not having had the advantage of a personal examination of this region. _structure of etna._--so large is etna that it would enclose within its ample skirts several cones of the size of vesuvius. it rises to a height of nearly , feet above the waters of the mediterranean,[ ] and is planted on a floor consisting of stratified marine volcanic matter, with clays, sands, and limestones of newer pliocene age. its base is nearly circular, and has a circumference of english miles. in ascending its flanks we pass successively over three well-defined physical zones: the lowest, or fertile zone, comprising the tract around the skirts of the mountain up to a level of about feet, being well cultivated and covered by dwellings surrounded by olive groves, fields, vineyards, and fruit-trees; the second, or forest zone, extending to a level of about feet, clothed with chestnut, oak, beech, and cork trees, giving place to pines; and the third, extending to the summit and called "the desert region," a waste of black lava and scoriæ with mighty crags and precipices, terminating in a snow-clad tableland, from which rises the central cone, feet high, emitting continually steam and sulphurous vapours, and in the course of almost every century sending forth streams of molten lava. the forest zone is remarkable for the great number of minor craters which rise up from the midst of the foliage, and are themselves clothed with trees. sartorius von waltershausen has laid down on his map of etna about of these cones and craters, some of which, like those of auvergne, have been broken down on one side. many of these volcanoes of second or third magnitude lie outside the forest zone, both above and below it; such as the double hill of monti rossi, near nicolosi, formed in , which is feet in height, and two miles in circumference at its base. sir c. lyell observes that these minor crater-cones present us with one of the most delightful and characteristic scenes in europe. they occur of every variety of height and size, and are arranged in picturesque groups. however uniform they may appear when seen from the sea or the plains below, nothing can be more diversified than their shape when we look from above into their ruptured craters. the cones situated in the higher parts of the forest zone are chiefly clothed with lofty pines; while those at a lower elevation are adorned with chestnuts, oaks, and beech trees. these cones have from time to time been buried amidst fresh lava-streams descending from the great crater, and thus often become obliterated. [illustration: fig. .--ideal section through etna. (after lyell.)--a. axis of present cone of eruption; b. axis of extinct cone of eruption; _a._ older lavas, chiefly trachytic; _b._ newer lavas, erupted (with _a_) before origin of the val del bove; _c._ scoria and lava of recent age; t. tertiary strata forming the foundation to the volcanic rocks. the position of the val del bove before its formation is shown by the lightly-shaded portion above b.] (_b._) _val del bove._--the most wonderful feature of mount etna is the celebrated val del bove (valle del bue), of which s. von waltershausen has furnished a very beautiful plate[ ]--a vast amphitheatre hewn out of the eastern flank of the mountain, just below the snow-mantled platform. it is a physical feature somewhat after the fashion of monte somma in vesuvius, but exceeds it in magnitude as etna exceeds vesuvius. the val del bove is about five miles in diameter, bounded throughout three-fourths of its circumference by precipitous walls of ashes, scoriæ, and lava, traversed by innumerable dykes, and rising inwards to a height of between and feet. towards the east the cliffs gradually fall to a height of about feet, and at this side the vast chasm opens out upon the slope of the mountain. at the head of the val del bove rises the platform, surmounted by the great cone and crater. it will thus be seen that by means of this hollow we have access almost to the very heart of the mountain. what is very remarkable about the structure of this valley is that the beds exhibit "the _quâ-quâ_ versal dip"--in other words, they dip away on all sides from the centre--which has led to the conclusion that in the centre is a focus of eruption which had become closed up antecedently to the formation of the valley itself. lyell has explained this point very clearly by showing that this focus had ceased to eject matter at some distant period, and that the existing crater at the summit of the mountain had poured out its lavas over those of the extinct orifice. this was prior to the formation of the val del bove itself; and the question remains for consideration how this vast natural amphitheatre came to be hollowed out; for its structure shows unquestionably that it owes its form to some process of excavation. in the first place, it is certainly not the work of running water, as in the case of the cañons of colorado; the porous matter of which the mountain is formed is quite incapable of originating and supporting a stream of sufficient volume to excavate and carry away such enormous masses of matter within the period required for the purpose. we must therefore have recourse to some other agency. numerous illustrations are to be found of the explosive action of volcanoes in blowing off either the summits of mountains, or portions of their sides. for example, there is reason for believing that the first result of the renewed energy of vesuvius was to blow into the air the upper surface of the mountain. again, so late as , during a violent earthquake in java, a country which has been repeatedly devastated by earthquakes and volcanic eruptions, the mountain of galongoon, which was covered by a dense forest, and situated in a fertile and thickly-peopled region, and had never within the period of tradition been in activity, was thus ruptured by internal forces. in the month of july , after a terrible earthquake, an explosion was heard, and immense columns of boiling water, mixed with mud and stones, were projected from the mountain like a water-spout, and in falling filled up the valleys, and covered the country with a thick deposit for many miles, burying villages and their inhabitants. during a subsequent eruption great blocks of basalt were thrown to a distance of seven miles; the result of all being that an enormous semicircular gulf was formed between the summit and the plain, bounded by steep cliffs, and bearing considerable resemblance to the val del bove. other examples of the power of volcanic explosions might be cited; but the above are sufficient to show that great hollows may thus be formed either on the summits or flanks of volcanic mountains. chasms may also be formed by the falling in of the solidified crust, owing to the extrusion of molten matter from some neighbouring vent of eruption; and it is conceivable that by one or other of these processes the vast chasm of the val del bove on the flanks of etna may have been produced. (_c._) _the physical history of etna._--the physical history of etna seems to be somewhat as follows:-- _first stage._--somewhere towards the close of the tertiary period--perhaps early pliocene or late miocene--a vent of eruption opened on the floor of the mediterranean sea, from which sheets of lava were poured forth, and ashes mingled with clays and sands, brought down from the neighbouring lands, were strewn over the sea-bed. during a pause in volcanic activity, beds of limestone with marine shells were deposited. _second stage._--this sea-bed was gradually upraised into the air, while fresh sheets of lava and other _ejecta_ were accumulated round the vents of eruption, of which there were two principal ones--the older under the present val del bove, the newer under the summit of the principal cone. thus was the mountain gradually piled up. _third stage._--the vent under the val del bove ceased to extrude more matter, and became extinct. meanwhile the second vent continued active, and, piling up more and more matter round the central crater, surmounted the former vent, and covered its _ejecta_ with newer sheets of lava, ashes, and lapilli, while numerous smaller vents, scattered all over the sides of the mountain, gave rise to smaller cones and craters. _fourth stage._--this stage is signalised by the formation of the val del bove through some grand explosion, or series of explosions, by which this vast chasm was opened in the side of the mountain, as already explained. _fifth stage._--this represents the present condition of the mountain, whose height above the sea is due, not only to accumulation of volcanic materials round the central cone, but to elevation of the whole island, as evinced by numerous raised beaches of gravel and sand, containing shells and other forms of marine species now living in the waters of the mediterranean.[ ] since then the condition and form of the mountain has remained very much the same, varied only by the results of occasional eruptions. (_d._) _dissimilarity in the constitution of the lavas of etna and vesuvius._--before leaving the subject we have been considering, it is necessary that i should mention one remarkable fact connected with the origin of the lavas of etna and vesuvius respectively; i refer to their essential differences in mineral composition. it might at first sight have been supposed that the lavas of these two volcanic mountains--situated at such a short distance from each other, and evidently along the same line of fracture in the crust--would be of the same general composition; but such is not the case. in the lava of vesuvius leucite is an essential, and perhaps the most abundant mineral. it is called by zirkel _sanidin-leucitgestein_. (see plate iv.) but in that of etna this mineral is (as far as i am aware) altogether absent. we have fortunately abundant means of comparison, as the lavas of these two mountains have been submitted to close examination by petrologists. in the case of the vesuvian lavas, an elaborate series of chemical analyses and microscopical observations have been made by the rev. professor haughton, of dublin university, and the author,[ ] from specimens collected by professor guiscardi from the lava-flows extending from to , in every one of which leucite occurs, generally as the most abundant mineral, always as an essential constituent. on the other hand, the composition of the lavas of etna, determined by professor a. von lasaulx, from specimens taken from the oldest (vorätnäischen) sheets of lava down to those of the present day, indicates a rock of remarkable uniformity of composition, in which the components are plagioclase felspar, augite, olivine, magnetite, and sometimes apatite; but of leucite we have no trace.[ ] in fact, the lavas of etna are very much the same in composition as the ordinary basalts of the british isles, while those of vesuvius are of a different type. this seems to suggest an origin of the two sets of lavas from a different deep-seated magma; the presence of leucite in such large quantity requiring a magma in which soda is in excess, as compared with that from which the lavas of etna have been derived.[ ] [ ] _mémoires pour servir_, etc., vol. ii. [ ] daubeny, _volcanoes_, p. . [ ] von waltershausen, _der Ætna_, edited by a. von lasaulx. [ ] lyell, _principles of geology_, vol. ii., edition . [ ] its height, as determined by captain smyth in trigonometrically, was , feet, and afterwards by sir j. herschel barometrically, , feet. [ ] _atlas des Ætna_ (weimar, ), in which the different lava-streams of , , , , , , and are delineated. [ ] sir william hamilton observes that history is silent regarding the first eruptions of etna. it was in activity before the trojan war, and even before the arrival of the "sizilien" settlers. diodorus and thucydides notice the earliest recorded eruptions, those from to b.c., during which time the mountain was thrice in eruption. later eruptions took place in the year , , , b.c. in the year b.c., in the reign of julius cæsar, there was a very violent outburst of volcanic activity.--_neuere beobachtungen über die vulkane italiens und am rhein_, p. , frankfurt ( ). [ ] "report on the chemical and mineralogical characters of the lavas of vesuvius from to ," _transactions of the royal irish academy_, vol. xxvi. ( ). in the lava of leucite was found to reach . per cent. of the whole mass. in that of granatello, , it reaches its lowest proportion--viz., . per cent. [ ] a. von lasaulx, in von waltershausen's _der Ætna_, book ii., x. . [ ] the view of professor judd, that leucite easily changes into felspar, and that some ancient igneous rocks which now contain felspar were originally leucitic, does not seem to be borne out by the above facts. in such cases the felspar crystals ought to retain the forms of leucite. see _volcanoes_, th edition, p. . chapter iii. the lipari islands, stromboli. (_a._) a brief account of this remarkable group of volcanic islands must here be given, inasmuch as they seem to be representatives of a stage of volcanic action in which the igneous forces are gradually losing their energy. according to daubeny, the volcanic action in these islands seems to be developed along two lines, nearly at right angles to each other, one parallel to that of the apennines, beginning with stromboli, intersecting panaria, lipari, and vulcano; the other extending from panaria to salina, alicudi, and felicudi, and again visible in the volcanic products which make their appearance at ustica. (see map, fig. .) the islands lie between the north coast of sicily and that of italy, and from their position seem to connect etna with vesuvius; but this is very problematical, as would appear from the difference of their lavas. the principal islands are those of stromboli, panaria, lipari, vulcano, salina, felicudi, and alicudi. these three last are extinct or dormant, but salina contains a crater, rising, according to daubeny, not less than feet above the sea.[ ] vulcano (referred to by strabo under the name of hiera) consists of a crater which constantly emits large quantities of sulphurous vapours, but was in a state of activity in the year , when, after frequent earthquake shocks and subterranean noises, it vomited forth during fifteen days showers of sand, together with clouds of smoke and flame, altering materially the shape of the crater from which they proceeded. [illustration: lipari islands. fig. .--map to show the position of these islands, showing the branching lines of volcanic action--one parallel to that of the apennines, the other stretching westwards at right angles thereto.] the islands of lipari are formed of beds of tuff, penetrated by numerous dykes of lava, from which uprise two or three craters, formed of pumice and obsidian passing into trachyte. volcanic operations might have here been said to be extinct, were it not that their continuance is manifested by the existence of hot springs and "stufes," or vapour baths, at st. calogero, about four miles from the town of lipari. daubeny considers it not improbable that this island may have had an active volcano even within the historical period, a view which is borne out by the statement of strabo.[ ] [illustration: fig. .--island of vulcano, one of the lipari group, in eruption.--(after sir w. hamilton.)] (_b._) but by far the most remarkable island of the group, as regards its present volcanic condition, is stromboli, which has ever been in active eruption from the commencement of history down to the present day. professor judd, who visited this island in , and has produced a striking representation of its aspect,[ ] gives an account of which i shall here avail myself.[ ] the island is of rudely circular outline, and rises into a cone, the summit of which is feet above the level of the mediterranean. from a point on the side of the mountain masses of vapour are seen to issue, and these unite to form a cloud over the summit; the outline of this vapour-cloud varying continually according to the hygrometric state of the atmosphere, and the direction and force of the wind. at the time of professor judd's visit, the vapour-cloud was spread in a great horizontal stratum overshadowing the whole island; but it was clearly seen to be made up of a number of globular masses, each of which is a product of a distinct outburst of volcanic forces. viewed at night-time, stromboli presents a far more striking and singular spectacle. when watched from the deck of a vessel, a glow of red light is seen to make its appearance from time to time above the summit of the mountain; it may be observed to increase gradually in intensity, and then as gradually to die away. after a short interval the same appearances are repeated, and this goes on till the increasing light of dawn causes the phenomenon to be no longer visible. the resemblance presented by stromboli to a "flashing light" on a most gigantic scale is very striking, and the mountain has long been known as "the lighthouse of the mediterranean." the mountain is built up of ashes, slag, and scoriæ, to a height of (as already stated) over feet above the surface of the sea; but, as professor judd observes, this by no means gives a just idea of its vast bulk. soundings in the sea surrounding the island show that the bottom gradually shelves around the shores to a depth of nearly fathoms, so that stromboli is a great conical mass of cinders and slaggy materials, having a height above its floor of about feet, and a base the diameter of which exceeds four miles. the crater of stromboli is situated, not at the apex of the cone, but at a distance of feet below it. the explosions of steam, accompanied by the roaring as of a smelting furnace, or of a railway engine when blowing off its steam, are said by judd to take place at very irregular intervals of time, "varying from less than one minute to twenty minutes, or even more." on the other hand, hoffmann describes them as occurring at "perfectly regular intervals," so that, perhaps, some variation has taken place within the interval of about forty years between each observation. both observers agree in stating that lava is to be seen welling up from some of the apertures within the crater, and pouring down the slope towards the sea, which it seldom or never reaches.[ ] the intermittent character of these eruptions appears to be due, as mr. scrope has suggested, to the exact proportion between the expansive and repressive forces; the expansive force arising from the generation of a certain amount of aqueous vapour and of elastic gas; the repressive, from the pressure of the atmosphere and from the weight of the superincumbent volcanic products. steam is here, as in a steam-engine, not the originating agent in the phenomena recorded; but the result of water coming in contact with molten lava constantly welling up from the interior, by which it is converted into steam, which from time to time acquires sufficient elastic force to produce the eruptions; the water being obviously derived from the surrounding sea, which finds its way by filtration through fissures, or through the porous mass of which the mountain is formed. were it not for the access of water this volcano would probably appear as a fissure-cone extruding a small and continuous stream of molten lava. the adventitious access of the sea water gives rise to the phenomena of intermittent explosions. the vitality of the volcano is therefore due, not to the presence of water, but to the welling up of matter from the internal reservoir through the throat of the volcano. _pantelleria._--this island, lying between the coast of sicily and cape bon in africa, is wholly volcanic. it has a circumference of thirty miles, and from its centre rises an extinct crater-cone to a height of about feet. the flanks of this volcano are diversified by several fresh craters and lava-streams, while hot springs burst out with a hissing noise on its southern flank, showing that molten matter lies below at no very great depth. this island probably lies along the dividing line between the non-volcanic and volcanic region of the mediterranean, and is consequently liable to intermittent eruptions. it was at a short distance from this island that the remarkable submarine outburst of volcanic forces took place on october th, , for an account of which we are indebted to colonel j. c. mackowen.[ ] on that day, after a succession of earthquake shocks, the inhabitants were startled by observing a column of "smoke" rising out of the sea at a distance of three miles, in a north-westerly direction. the governor, francesco valenza, having manned a boat, rowed out towards the fiery column, and on arriving found it to consist of black scoriaceous bombs, which were being hurled into the air to a height of nearly thirty yards; some of them burst in the air, others, discharging steam, ran hissing over the water; many of them were very hot, some even red-hot. one of these bombs, measuring two feet in diameter, was captured and brought to shore. it was observed that after the eruption the earthquake shocks ceased. a vast amount of material was cast out of the submarine crater, forming an island yards in length and rising up to nine feet above the surface, but after a few days it was broken up and dispersed over the sea-bed by the action of the waves. [ ] _volcanoes_, p. . these islands are described by hoffmann, _poggendorf annal._, vol. xxvi. ( ); also by lyell, _principles of geology_, vol. ii., and by judd, who personally visited them, and gives a very vivid account of their appearance and structure. [ ] strabo, lib. vi. [ ] judd, _volcanoes_, p. . [ ] stromboli has also been described by spallanzani, hoffmann, daubeny, and others. the account of judd is the most recent. of this island strabo says, "strongyle a rotundate figuræ sic dicta, ignita ipsa quoque, violentia flammarum minor, fulgore excellens; ibi habitasse Æcolum ajunt."--lib. vi. [ ] _poggend. annal._, vol. xxvi., quoted by daubeny. [ ] communicated by captain petrie to the victoria institute, st february . see also a detailed and illustrated account of the eruption communicated by a. ricco to the _annali dell' ufficio centrale meteorologico e geodonamico_, ser. ii., parte , vol. xi. summarised by mr. butler in _nature_, april , . chapter iv. the santorin group. [illustration: fig. .--ideal section through the gulf of santorin, to show the structure of the submerged volcano.--_a._ island of aspronisi; _b._ island of thera; . old kaimeni island; . new kaimeni island; . little kaimeni island.] (_a._) before leaving the subject of european active volcanoes, it is necessary to give some account of the remarkable volcanic island of santorin, in the grecian archipelago. this island for years has been the scene of active volcanic operations, and in its outline and configuration, both below and above the surface of the mediterranean, presents the aspect of a partially submerged volcanic mountain. (see section, fig. .) if, for example, we can imagine the waters of the sea to rise around the flanks of vesuvius until they have entered and overflowed to some depth the interior caldron of somma, thus converting the old crater into a crescent-shaped island, and the cone of vesuvius into an island--or group of islands--within the caldron, then we shall form some idea of the appearance and structure of the santorin group. _form of the group._--the principal island, thera, has somewhat the shape of a crescent, breaking off in a precipitous cliff on the inner side, but on the outer side sloping at an angle of about fifteen degrees into deep water. continuing the curvature of the crescent, but separated by a channel, is the island of therasia; and between this and the southern promontory of thera is another island called aspronisi. all these islands, if united, would form the rim of a crater, in which the volcanic matter slopes outward into deep water, descending at a short distance to a depth of fathoms and upwards. in the centre of the gulf thus formed rise three islands, called the old, new, and little kaimenis. these may be regarded as cones of eruption, which history records as having been thrown up at successive intervals. according to pliny, the year b.c. gave birth to old kaimeni, also called hiera, or the sacred isle; and in the first year of our era thera (the divine) made its appearance above the water, and was soon joined to the older island by subsequent eruptions. old kaimeni also increased in size by the eruptions of and . a century and a half later, in , another eruption produced the cone and crater called micra-kaimeni. thus were formed, or rather were rendered visible above the water, the central craters of eruption; and between these and the inner cliff of thera and therasia is a ring of deep water, descending to a depth of over fathoms. so that, were these islands raised out of the sea, we should have presented to our view a magnificent circular crater about six miles in diameter, bounded by nearly vertical walls of rock from to feet in height, and ruptured at one point, from the centre of which would rise two volcanic cones--namely, the kaimenis--one with a double crater, still foci of eruption, and from time to time bursting forth in paroxysms of volcanic energy, of which those of , , and were the most violent and destructive.[ ] of this last i give a bird's-eye view (fig. ). the only rock of non-volcanic origin in these islands consists of granular limestone and clay slate forming the ridge of mount st. elias, which rises to a height of feet at the south-eastern side of the island of thera, crossing the island from its outer margin nearly to the interior cliff, so that the volcanic materials have been piled up along its sides. the rocks of st. elias are much more ancient than any of the volcanic materials around; and, as bory st. vincent has shown, have been subjected to the same flexures, dip and strike, as those sedimentary rocks which go to form the non-volcanic islands of the grecian archipelago. [illustration: fig. .--bird's-eye view of the gulf of santorin during the volcanic eruption of february .--(after lyell.)] [illustration: _ground plan of rocca monfina_ fig. .--rocca monfina, in southern italy, showing a crater-ring of trachytic tuffs, from the midst of which, according to judd, an andesite lava-cone has been built up. compare with the santorin group.] (_b._) _origin of the santorin group._--in reference to the origin of the santorin group, lyell regards it as a remnant of a great volcanic mountain which possessed a focus of eruption rising in the position of the present foci, but afterwards partially destroyed and the whole submerged to a depth of over feet. but another explanation is open to us, and one not inconsistent with what we now know of the physical changes to which the mediterranean has been subjected since early tertiary times. to my mind it is difficult to conceive how such a volcanic mountain as that of santorin could have been formed under water; while, on the other hand, its physical structure and contour bear so striking a resemblance (as already observed) to those of vesuvius and rocca monfina that we are much tempted to infer that it had a somewhat similar origin. now we know that vesuvius was built up by means of successive eruptions taking place under the air; and the question arises whether it could be possible that santorin had a similar origin owing to the waters of the mediterranean having been temporally lowered at a later tertiary epoch. it has been stated by m. fouqué that the age of the more ancient volcanic beds of santorin belong, as shown by the included fossils, to the newer pliocene epoch. these are of course the unsubmerged, and therefore more recent strata, and may have been recently upheaved during one or more of the outbursts of volcanic energy. but it seems an impossibility that the gulf of santorin, with its precipitous walls and deep circular interior channel, as shown by the ideal section (fig. ), could have been formed otherwise than under the air. we are led, therefore, to inquire whether there was a time in the history of the mediterranean, since the eocene period, when the waters were lower than at present. that this was the case we have clear evidence. the remains of elephants, hippopotami, and other animals, which have been discovered in great numbers in the maltese caves, show that this island was united to sicily, and this again to europe, during the later pliocene epoch, so as to have become the abode of an europasian fauna. according to dr. wallace, a causeway of dry land existed, stretching from italy to tunis in north africa through the maltese islands--an inference involving the lowering of the waters of the mediterranean by several hundred feet.[ ] there is every reason for supposing that the old volcano of santorin was in active eruption at this period; and its history may be considered to be similar to that of vesuvius until, at the rising of the waters during the pluvial (or post-pliocene) epoch, during which they rose higher than at present, santorin was converted into a group of islands, slightly differing in form from those of the present day. this view seems to meet the difficulties regarding the origin of this group, difficulties which lyell had long since clearly recognised. (_c._) _limit of the mediterranean volcanic region._--with the santorin group we conclude our account of the active european volcanoes. it may be observed, however, that from some cause not ascertained the volcanic districts of the mediterranean and its shores are confined to the north side of that great inland sea; so that as regards vulcanicity the african coast presents a striking contrast to that of the opposite side. if we draw a line from the shores of the levant to the straits of gibraltar, by candia, malta, and to the south of pantelleria and sardinia, we shall find that the volcanic islands and districts of the mainland lie to the north of it.[ ] this has doubtless some connection with the internal geological structure. the immunity of the libyan desert from volcanic irruptions is in keeping with the remarkably undisturbed condition of the secondary strata, which seldom depart much from the horizontal position; while the igneous rocks of the atlas mountains are probably of great geological antiquity. on the other hand, the secondary and tertiary formations of the northern shores and islands of the mediterranean are generally characterised by the highly-inclined, flexured, and folded position of the strata. hence we may suppose that the crust over the region lying to the north of the volcanic line, owing to its broken and ruptured condition, was less able to resist the pressure of the internal forces of eruption than that lying to the south of it; and that, in consequence, vents and fissures of eruption were established over the former of these regions, while they are absent in the latter. [ ] fuller details will be found in daubeny's _volcanoes_, chap. xviii., and lyell's _principles of geology_, vol. ii. p. (edition ). the bird's-eye view is taken from this latter work by kind permission of the publisher, mr. j. murray, as also the accompanying ideal section, fig. . [ ] wallace, _geographical distribution of animals_ ( ). the author's _sketch of geological history_, p. (deacon & co., ). [ ] the _volcanic area_ lying to the north of this line will include sardinia, sicily, pantelleria, the grecian archipelago, asia minor, and syria; the _non-volcanic area_ lying to the south of this line will include the african coast, malta, isles of crete and cyprus. the isle of pantelleria is apparently just on the line, which, continued eastward, probably follows the north coast of cyprus, parallel to the strike of the strata and of the central axis of that island.--see "carte géologique de l'île de chypre, par mm. albert gaudry et amedée damour" ( ). chapter v. european extinct or dormant volcanoes. we are naturally led on from a consideration of the active volcanoes of europe to that of volcanoes which are either dormant or extinct in the same region. such are to be found in italy, central france, both banks of the rhine and moselle, the westerwald, vogelsgebirge, and other districts of germany; in hungary, styria, and the borders of the grecian archipelago. but the subject is too large to be treated here in detail; and i propose to confine my observations to some selected cases which are to be found in southern italy, central france, and the rhenish districts, where the volcanic features are of so recent an age as to preserve their outward form and structure almost intact. (_a._) _southern italy._--extinct volcanoes and volcanic rocks occupy considerable tracts between the western flanks of the apennines and the mediterranean coast in the neapolitan and roman states, forming the remarkable group of the phlegræan fields (campi phlegræi), with the adjoining islands of ischia, procida, nisida, vandolena, ponza, and palmarola; at melfi and avellino. all the region around rome extending along the western slopes of the apennines from velletri to orvieto, together with mount annato in tuscany, is formed of volcanic material, and the same may be said of a large part of the island of sardinia. from these districts i shall select some points which seem to be of special interest. _monte nuovo and the phlegræan fields._--the tract of which this celebrated district forms a part lies as it were in a bay of the apennine limestone of jurassic age. the floor of this bay is composed of puzzolana, a name given to beds of volcanic tuff of great thickness, and rising into considerable hills in the vicinity of the city of naples, such as that of st. elmo. its composition is peculiar, as it is chiefly formed of small pieces of pumice, obsidian, and trachyte, in beds alternating with loam, ferriferous sand, and fragments of limestone. it is evidently of marine formation, as sir william hamilton, professor pilla, and others have detected sea-shells therein, of the genera _ostræa_, _cardium_, _pecten_ and _pectunculus_, _buccinum_, etc. it is generally of a greyish colour, and sometimes sufficiently firm to be used as a building stone. the roman campagna is largely formed of similar materials, which were deposited at a time when the districts in question were submerged, and matter was being erupted from volcanic vents at various points around, and spread over the sea-bed. such is the character of the general floor on which the more recent crater-cones of this district have been built. these are numerous, and all extinct with the exception of the solfatara, near puzzuoli, from which gases mixed with aqueous vapour are continually being exhaled. the gases consist of sulphuretted hydrogen mixed with a minute quantity of muriatic acid.[ ] this district is also remarkable for containing several lakes occupying the interiors of extinct craters; amongst others, lake avernus, which, owing to its surface having been darkened by forests, and in consequence of the effluvia arising from its stagnant waters, has had imparted to it a character of gloom and terror, so that homer in the _odyssey_ makes it the entrance to hell, and describes the visit of ulysses to it. virgil follows in his steps. another lake of similar origin is lake agnano. here also is the grotto del cane, a cavern from which are constantly issuing volumes of carbonic acid gas combined with much aqueous vapour, which is condensed by the coldness of the external air, thus proving the high temperature of the ground from which the gaseous vapour issues. this whole volcanic region, so replete with objects of interest,[ ] may be considered, as regards its volcanic character, in a moribund condition; but that it is still capable of spasmodic movement is evinced by the origin of monte nuovo, the most recent of the crater-cones of the district. this mountain, rising from the shore of the bay of baiæ, was suddenly formed in september th, , and rises to a height of feet above the sea-level. it is a crater-cone, and the depth of the crater has been determined by the italian mineralogist pini to be english feet; its bottom is thus only feet above the sea-level. a portion of the base of the cone is considered partly to occupy the site of the lucrine lake, which was itself nothing more than the crater of a pre-existent volcano, and was almost entirely filled up during the explosion of . monte nuovo is composed of ashes, lapilli, and pumice-stones; and its sudden formation, heralded by earthquakes, and accompanied by the ejection of volcanic matter mixed with fire and water, is recorded by falconi, who vividly depicts the terror and consternation of the inhabitants of the surrounding country produced by this sudden and terrible outburst of volcanic forces.[ ] (_b._) _central italy and the roman states._--the tract bordering the western slopes of the apennines northward from naples into tuscany, and including the roman states, is characterised by volcanic rocks and physical features of remarkable interest and variety. these occur in the form of extinct craters, sometimes filled with water, and thus converted into circular lakes; or of extensive sheets and conical hills of tuff; or, finally, of old necks and masses of trachyte and basalt, sometimes exhibiting the columnar structure. the eternal city itself is built on hills of volcanic material which some observers have supposed to be the crater of a great volcano; but ponzi, brocchi, and daubeny all concur in the opinion that this is not the case, as will clearly appear from the following account. the geological structure of the valley of the tiber at rome is very clearly described by professor ponzi in a memoir published in , from which the accompanying section is taken.[ ] (fig. .) from this it will be seen that "the seven-hilled city" is built upon promontories of stratified volcanic tuff, of which the campagna is formed, breaking off along the banks of the tiber, the hills being the result of the erosion, or denudation, of the strata along the side of the river valley. as the strata dip from west to east across the course of the river, it follows that those on the western banks are below those on the opposite side; and thus the marine sands and marls which underlie the volcanic tuff, and are concealed by it along the eastern side of the valley, emerge on the west, and form the range of hills on that side. such being the structure of the formations under rome, it is evident that it is not "built on a volcano." [illustration: fig. .--geological section across the valley of the tiber at rome. . alluvium of the tiber; . diluvium; . volcanic tuff (recent deposits); . sands, etc.; . blue marl (sub-apennine deposits).] the tuff contains fragments of lava and pebbles of apennine limestone, and was deposited under the waters of an extensive lake at a time when volcanic action was rife amidst the alban hills. this lacustrine formation rests in turn on deposits of marine origin, containing oysters, patellæ, and other sea-shells, of which the chain of hills on the right bank of the tiber is chiefly formed. the district around albano lying to the south of rome is of peculiar interest from the assemblage of old crater-lakes which it contains; as, for instance, those of albano, vallariccia, nemi, juturna, and the lake of gabii. the lake of albano, one of the most beautiful sheets of water in the world, is about six miles in circumference, and surrounded by beds of peperino, a variety of tuff presenting a bright, undecomposed aspect when newly broken. the level of this lake was lowered by the romans during the siege of veii by means of a tunnel, so that the waters are feet lower than the level at which they originally stood. in the same district is the lake of nemi, very regular in its circular outline; that of juturna lying near the foot of the alban hills, and that of ariccia lying in a deep hollow eight miles in circumference;--all may be supposed to have been the craters of extinct volcanoes, both by reason of their shape and of the materials of which they are formed. all these old craters are, however, according to daubeny, "only the dependencies and offshoots, as it were, of the great extinct volcano, the traces of which still remain upon the summit of the alban hills, and which is comparable in its form to that of vesuvius, as it is surrounded by an outer circle of volcanic rock comparable to that of somma."[ ] to the north of the city of rome are several crateriform lakes, some of which are of great size, such as that of bolsena, over twenty miles in circumference, and the lago di bracciano, almost as large, and lying about twelve miles from the city. these extensive sheets of water are surrounded by banks of tuff and volcanic sand, in which fragments of augite, leucite, and crystals of titanite are distributed. the town of viterbo is built up at the foot of a steep hill called monte cimini, the lower part of which is composed of trachyte; this is surmounted by tuff, which appears to have been ejected from an extinct crater occupying the summit of the mountain, and now converted into a lake called the lake of vico. this crater is perfectly circular, and from its centre rises a little conical hill covered by trees. (_c._) _physical history._--space does not permit of a fuller description of the remarkable volcanic features of the tract lying along the western slope of the apennines; but from what has been stated it will be clear that volcanic forces have been in operation at one time on a grand scale in the roman states and the south of tuscany, over a tract extending from mount annato to velletri and segni. this tract was separated from that of the neapolitan volcanic region by a range of limestone hills of jurassic age between segni and gaeta, a protrusion of the alban hills westward; but the general structure and physical history of both regions are probably very similar, with the exception that the igneous forces still retain their vitality in the more southerly region. in the case of the roman volcanic district, a bay seems to have been formed about the close of the miocene period, bounded on all sides but the west by hills of limestone, over whose bed strata of marl, sandstone, and conglomerate were deposited. this tract was converted by subsequent movements into a fresh-water lake, and contemporaneously volcanic operations commenced over the whole region, and beds of tuff, often containing blocks of rock ejected from neighbouring craters, were deposited over those of marine origin. meanwhile numerous crater-cones were thrown up; and, as the land gradually rose, the waters of the lake were drained off, leaving dry the campagna and plain of the tiber. ultimately the volcanic fires smouldered down and died out, whether within the historic epoch or not is uncertain; lakes were formed within the now dormant craters, and the face of nature gradually assumed a more placid and less forbidding aspect over this memorable region, destined to be the site of rome, the mistress of the world. [ ] as determined by daubeny in . [ ] including the ruins of the temple of serapis, whose pillars are perforated by marine boring shells up to a height of about feet from their base; indicating that the land had sunk down beneath the sea, and afterwards been elevated to its present level. [ ] the account of falconi, and another by pietro giacomo di toledo, are given by sir w. hamilton, _op. cit._, p. , and also reproduced by sir c. lyell, _principles_, vol. i. p. . [ ] guiseppe ponzi, "sulla storia fisica del bacino di roma," _annali di scienze fisiche_ (roma, ). [ ] daubeny, _volcanoes_, p. . chapter vi. extinct volcanoes of central france. (_a._) _general structure of the auvergne district._--from a granitic and gneissose platform situated near the centre of france, and separated from the western spurs of the alps by the wide valley of the rhone, there rises a group of volcanic mountains surpassing in variety of form and structure any similar mountain group in europe, and belonging to an epoch ranging from the middle tertiary down almost to the present day. this volcanic group of mountains gives rise to several important rivers, such as the loire, the allier, the soule (a branch of the loire), the creuse, the dordogne, and the lot; and in the plomb du cantal attains an elevation of feet above the sea. its southern section, that of mont dore, the cantal, and the haute loire, is characterised by magnificent valleys, traversing plateaux of volcanic lava, and exhibiting the results of river erosion on a grand scale; while its northern section, that of the puy de dôme, presents to us a varied succession of volcanic crater-cones and domes, with their extruded lava-streams, almost as fresh and unchanged in form as if they had only yesterday become extinct. a somewhat similar, but less important, chain of extinct volcanoes also occurs in the velay and vivarais, between the upper waters of the loire and the allier, in the vicinity of the town of le puy.[ ] the principal city in this region is clermont-ferrand, lying near the base of the puy de dôme, and ever memorable as the birthplace of blaise pascal.[ ] [illustration: fig. .--generalised section through the puy de dôme and vale of clermont, distance about ten miles. the general floor formed of granite and gneiss (g); d. domite-lava of the puy de dôme; sc. cones of ashes and scoriæ; l. lava-sheets; a. alluvium of the vale of clermont and lake deposits.] the physical structure of this region is on the whole very simple. the fundamental rocks consist of granite and gneiss passing into schist, all of extreme geological antiquity, forming a vast platform gradually rising in a southerly direction towards the head waters of the loire and the allier in the departments of haute loire, lozère, and ardèche. on this platform are planted the whole of the volcanic mountains. (see fig. .) the granitic plateau is bounded on the east, throughout a distance of about miles, by the wide and fertile plain of clermont, watered by the allier and its numerous branches descending from the volcanic mountains, and is about miles in width from east to west in the parallel of clermont, but gradually narrowing in a southerly direction, till at brioude it becomes an ordinary mountain ravine. the eastern margin of the plain is formed by another granitic ridge expanding into a plateau towards the south, and joining in with that already described; but towards the north and directly east of clermont it forms a high ridge traversed by the railway to st. Étienne and lyons, and descending towards the east into the valley of the loire. no more impressive view is to be obtained of the volcanic region than that from the summit of this second ridge, on arriving there towards evening from the city of lyons. at your feet lies the richly-cultivated plain of clermont, dotted with towns, villages, and hamlets, and decorated with pastures, orchards, vineyards, and numerous trees; while beyond rises the granitic plateau, breaking off abruptly along the margin of the plain, and deeply indented by the valleys and gorges along which the streams descend to join the allier. but the chief point of interest is the chain of volcanic crater-cones and dome-shaped eminences which rise from the plateau, amongst which the puy de dôme towers supreme. their individual forms stand out in clear and sharp relief against the western sky, and gradually fade away towards the south into the serried masses of mont dore and cantal, around whose summits the evening mists are gathering. except the first view of the mont blanc range from the crest of the jura, there is no scene perhaps which is calculated to impress itself more vividly on the memory than that here faintly described.[ ] [illustration: fig. .--transverse view of the puy de dôme and neighbouring volcanoes from the puy de chopine.--(after scrope.)] (_b._) _the vale of clermont._--the plain upon which we look down was once the floor of an extensive lake, for it is composed of various strata of sand, clay, marl, and limestone, containing various genera and species of fresh-water shells. these strata are of great thickness, perhaps a thousand feet in some places; and along with such shells as _paludina_, _planorbis_, and _limnæa_ are also found remains of various other animals, such as fish, serpents, batrachians, crocodiles, ruminants, and those of huge pachyderms, as _rhinoceros_, _dinotherium_, and _cænotherium_. this great lake, occupying a hollow in the old granitic platform of central france, must have been in existence for an extensive period, which mm. pomel, aymard, and lyell all unite in referring to that of the lower miocene. but what is to us of special interest is the fact that, in the deposits of this lake of the haute loire, with the exception of the very latest, there is no intermixture of volcanic products such as might have been expected to occur if the neighbouring volcanoes had been in activity during its existence. hence it may be supposed that, as scrope suggested, the waters of the lake were drained off owing to the disturbance in the levels of the country caused by the first explosions of the auvergne volcanoes.[ ] if this be so, then we possess a key by which to determine the period of the first formation of volcanoes in central france; for, as the animal remains enclosed in the lacustrine deposits of the vale of clermont belong to the early miocene stage, and the earliest traces of contemporaneous volcanic _ejecta_ are found only in the uppermost deposits, we may conclude that the first outburst of volcanic action occurred towards the close of the miocene period--a period remarkable for similar exhibitions of internal igneous action in other parts of the world. (_c._) _successive stages of volcanic action in auvergne._--the volcanic region here described, which has an area of about one hundred square miles, does not appear to have been at one and the same period of time the theatre of volcanic action over its whole extent. on the contrary, this action appears to have commenced at the southern border of the region in the cantal, and travelling northwards, to have broken out in the mont dore region; finally terminating its outward manifestations among the craters and domes of the puy de dôme. in a similar manner the volcanic eruptions of the haute loire and ardèche, lying to the eastward, and separated from those of the cantal by the granitoid ridge of the montagnes de margeride, belong to two successive periods referable very closely to those of the mont dore and the puy de dôme groups.[ ] the evidence in support of this view is very clear and conclusive; for, while the volcanic craters formed of ash, lapilli, and scoriæ, together with the rounded domes of trachytic rock of which the puy de dôme group is composed, preserve the form and surface indications of recently extinguished volcanoes, those which we may assume to have been piled up in the region of mont dore and cantal have been entirely swept away by prolonged rain and river action, and the sites of the ancient craters and cones of eruption are only to be determined by tracing the great sheets of lava up the sides of the valleys to their sources, generally situated at the culminating points of their respective groups. other points of evidence of the great antiquity of the latter groups might be adduced from the extent of the erosion which has taken place in the sheets of lava having their sources in the vents of the plomb du cantal and of mont dore, owing to which, magnificent valleys, many miles in length and hundreds of feet in depth, have been cut out of these sheets of lava and their supporting rocks, whether granitic or lacustrine, and the materials carried away by the streams which flow along their beds. these points will be better understood when i come to give an account of the several groups; and in doing so i will commence with that of the cantal.[ ] (_d._) _the volcanoes of the cantal._--the original crater-cones of this group have entirely disappeared throughout the long ages which have elapsed since the lava-streams issued forth from their internal reservoirs. the general figure of this group of volcanic mountains is that of a depressed cone, whose sides slope away in all directions from the central heights, which are deeply eroded by streams rising near the apex and flowing downwards in all directions towards the circumference of the mountain, where they enter the lot, the dordogne, and the allier. the orifice of eruption was situated at the plomb du cantal, formed of solid masses of trachyte, which, owing, as mr. scrope supposes, to a high degree of fluidity, were able to extend to great distances in extensive sheets, and were afterwards covered by repeated and widely-spread flows of basalt; so that the trachyte towards the margin of the volcanic area becomes less conspicuous than the basalt by which it is more or less concealed from view, or overlapped. extensive beds of tuff and breccia accompany the trachytic masses. magnificent sections of the rocks are laid open to view along the sides of the valleys, which are steep and rock-bound. except towards the south-west, about aurillac, where lacustrine strata overlie the granite, the platform from which rises the volcanic dome is composed of granitic or gneissose rocks. accompanying the lava-streams are great beds of volcanic agglomerate, which mr. scrope considers to have been formed contemporaneously with the lava which they envelop, and to be due to torrents of water tumultuously descending the sides of the volcano at periods of eruption, and bearing down immense volumes of its fragmental _ejecta_ in company with its lava-streams.[ ] nowhere throughout this region do beds of trachyte and basalt alternate with one another; in all cases the basalt is the newer of the two varieties of rock, and this is generally the case throughout the region here described. (_e._) _volcanoes of mont dore._--this mountain lies to the north of that of cantal, and somewhat resembles it in general structure and configuration. like cantal, it is destitute of any distinct crater; all that is left of the central focus of eruption being the solidified matter which filled the throat of the original volcano, and which forms a rocky mass of lava, rising in its highest point, the pic de saucy, to an elevation (as given by ramond) of feet above the level of the sea, thus exceeding that of the plomb du cantal by feet. its figure will be best understood by supposing seven or eight rocky summits grouped together within a circle of about a mile in diameter, from whence, as from the apex of an irregular and flattened cone, all the sides slope more or less rapidly downwards, until their inclination is gradually lost in the plain around. this dome-shaped mass has been deeply eroded on opposite sides by the valleys of the dordogne and chambon; while it is further furrowed by numerous minor streams.[ ] the great beds of volcanic rock, disposed as above stated, consist of prodigious layers of scoriæ, pumice-stones, and detritus, alternating with beds of trachyte and basalt, which often descend in uninterrupted currents till they reach the granite platform, and then spread themselves for miles around. the sheets of basalt are found to stretch to greater distances than those of trachyte, and have flowed as far as or miles from their orifices of eruption; while in some cases, on the east and north sides, they have extended as far as or miles from the central height. on the other hand, a radius of about ten miles from the centre would probably include all the streams of trachyte;--so much greater has been the viscosity of the basalt over the latter rock. some portions of these great sheets of lava, cut off by river valleys or eroded areas from the main mass of which they once formed a part, are found forming isolated terraces and plateaux either on the granitic platform, or resting on the fresh-water strata of the valley of the allier, while in a northern direction they overspread a large portion of the granitic plateau from which rise the puy de dôme and associated volcanic mountains. still more remarkable are the cases in which these lava-streams have descended into the old river channels which drained the granitic plateau. thus the current which took its origin in the puy gros descended into the valley of the dordogne, while another stream invaded the gorge of champeix on the eastern side. the more ancient lava-streams just described are invaded by currents and surmounted by cones of eruption of more recent date, similar to those of the puy de dôme group lying to the northward. such cones and currents, amongst which are the puy de tartaret and that of montenard, present exactly the same characters as those of this group, to which we shall return further on. (_f._) _volcanoes of the haute loire and ardèche._--separated by the valley of the allier and the granitic ridge of la margeride from the volcanic regions of cantal and mont dore is another volcanic region of great extent, which reaches its highest elevation in the central points of mont mezen, attaining an elevation (according to cordier) of feet, and formed of "clinkstone." the volcanic products of mezen have been erupted from one central orifice of vast size, and consist mainly of extensive sheets of "clinkstone," a variety of trachytic lava, which have taken courses mainly towards the north-west and south-east. these great sheets, one of which appears to have covered a space more than miles in length with an average breadth of miles, thus overspreading an estimated area of square miles, has been deeply eroded by streams draining into the loire, along whose banks the rocks tower in lofty cliffs; while it has also suffered enormous denudation, by which outlying fragments are disconnected from the main mass, and form flat-topped hills and plateaux as far distant as roche en reigner and beauzac, at the extreme distance (as stated above) of miles from the source of eruption. but even more remarkable than the above are the vast basaltic sheets which stretch away for a distance of miles by privas almost to the banks of the rhône, opposite montlimart. these have their origin amongst the clinkstone heights of mont mezen, and taking their course along the granitic plateau in a south-easterly direction, ultimately pass over on to the jurassic and cretaceous formations composing the plateau of the coiron, which break off in vertical cliffs from to feet in height, surmounting the slopes that rise from the banks of the ardèche and escourtais rivers near villeneuve de bere. this is probably one of the most extensive sheets of basalt with which we are acquainted in the european area, and it is only a remnant of a vastly greater original sheet.[ ] [illustration: fig. .--mont demise, near le puy, seen from the s.e. (after scrope.)-- . building standing on old breccia, rocks of the col; . road to brioude; . croix de la paille; . orgue d'expailly (basalt); . spot where human bones were found.] (_g._) _newer volcanoes of the haute loire (the velay and vivarais)._--subsequently to the formation of the lava-streams above described, and probably after the lapse of a lengthened period, the region of the haute loire and ardèche became the scene of a fresh outburst of volcanic action, during which the surface of the older lavas, or of the fundamental granite, was covered by numerous crater-cones and lava-streams strewn along the banks of the allier and of the loire for many miles. these cones and craters are not quite so fresh as those of the mont dôme group; those of the haute loire being slightly earlier in point of time, and, as daubeny shows, belonging to a different system. so numerous are these more recent cones and craters that scrope counted more than of them, and probably omitted many. the volcanic phenomena now described have a special interest as bearing on the question whether man was an inhabitant of this region at the time of these later eruptions. the question seems to be answered in the affirmative by the discovery of a human skull and several bones in the volcanic breccia of mont demise, in company with remains of the elephant (_e. primigenius_), rhinoceros (_r. tichorhinus_), stag, and other large mammifers. the discovery of these remains was made in the year , and the circumstances were fully investigated and reported upon by m. aymard, and afterwards by mr. poulett scrope, upon whose mind no possible doubt of the fact remained. from what we now know of the occurrence of human remains and works of art in other parts of france and europe, no surprise need be felt at the occurrence of human remains in company with some extinct mammalia in these volcanic tuffs, which belong to the post-pliocene or superficial alluvia antecedent to the historic period.[ ] (_h._) _mont dôme chain._--we now come to the consideration of the most recent of all the volcanic mountain groups of the region of central france, that of the puy de dôme, lying to the north of mont dore and cantal. we have seen that there is almost conclusive evidence that man was a witness to the later volcanic outbursts of the vivarais, and as these craters seem to be of somewhat earlier date than those of the puy de dôme group, we cannot doubt that they were in active eruption when human beings inhabited the country, and not improbably within what is known as the _historic period_. no mention, however, is made either by cæsar, pliny, or other roman writers of the existence of active volcanoes in this region. cæsar, who was a close observer, and who carried the roman arms into auvergne, makes no mention of such; nor yet does the elder pliny, who enumerated the known burning mountains of his day all over the roman empire. it is not till we come down to the fifth century of our era that we find any notices which might lead us to infer the existence of volcanic action in central france. this is the well-known letter written by sidonius apollonarius, bishop of auvergne, to alcinus avitus, bishop of vienne, in which the former refers to certain terrific terrestrial manifestations which had occurred in the diocese of the latter. but, as dr. daubeny observes, this is no evidence of volcanic action in auvergne, where sidonius himself resided; the terrestrial disturbances above referred to may have been earthquake shocks of extreme severity.[ ] but although we have no reliably historical record of volcanic action amongst the mountains of the mont dôme group, the fact that these are, comparatively, extremely recent will be evident to an observer visiting this district, and this conclusion is based on three principal grounds: first, because of the well-preserved forms of the original craters, though generally composed of very loose material, such as ashes, lapilli, and slag; secondly, because of the freshness of the lava-streams over whose rugged surfaces even a scanty herbage has in some places scarcely found a footing;[ ] and thirdly, because the lava from the crater-cones has invaded channels previously occupied by the earlier lavas, or those which had been eroded since the overflow of the great basaltic sheets of mont dore. still, as in the case of the valleys of lake aidot, of channonat, and of royat, these streams are sufficiently ancient to have given time for the existing rivers to have worn out in them channels of some depth, but bearing no comparison to the great valleys which had been eroded out of the more ancient lavas, such as those of the coiron, of the ardèche, and of the dordogne and chambon in the district of mont dore. (_i._) _dome-shaped volcanic hills._--i have previously (page ) referred to the two classes of volcanic eminences to be found in the chain of the puy de dôme; one indicated by the name itself, formed of a variety of trachytic lava called "domite," and of the form of a dome; the other, composed of fragmental matter piled up in the form of a crater or cup, often ruptured on one side by a stream of lava which has burst through the side, owing to its superior density. of the former class the puy de dôme and the grand sarcoui (see fig. ) are the most striking examples out of the five enumerated by scrope, while there is a large number, altogether sixty-one, belonging to the latter class. these domes and crater-cones, as already stated, rise from a platform of granite, either directly or from one formed of the lava-sheets of the mont dore region, which in turn overlies the granitic platform. of the nearly perfect craters there are the petit puy de dôme, lying partially against the northern flank of the greater eminence; the puy de cone, remarkable for the symmetry of its conical form, rising to a height of feet from the plain; and the puys de chaumont and thiolet lying to the north of the puy de dôme. of those to the south of this mount, two out of the three craters of the puy de barme and the puy de vichatel are perfect; but most of the crater-cones south of the puy de dôme are breached. some of the lava streams by which these craters were broken down flowed for long distances. that the lava followed the showers of ashes and lapilli forming the walls of the craters is rendered very evident in the case of the puy de la vache, whose lava-stream coalescing with those from the puy de la solas and puy noir, deluged the surrounding tracts and flowed down the channonat valley as far as la roche blanc in the vale of clermont. in the interior of the upper part of the crater still remaining may be seen the level (so to speak) to which the molten lava rose before it burst its barrier. this level is marked by a projecting platform of reddish or yellow material, rich in specular iron, apparently part of the frothy scum which formed on the surface of the lava and adhered to the side of the basin at the moment of its being emptied. space does not permit a fuller description of this remarkable assemblage of extinct volcanoes, and the reader must be referred for further details to the work of mr. scrope. i shall content myself with some further reference to the central figure in this grand chain, the puy de dôme itself. _ascent of the puy de dôme._--on ascending by the winding path up the steep side of the mount, and on reaching the somewhat flattened summit, the first objects which strike the eye are the massive foundations of the roman temple of mercury; they are hewn out of solid grey lava, altogether different from the rock of the puy de dôme itself, which must have been obtained from one of the lava-sheets of the mont dore group. to have carried these large blocks to their present resting-place must have cost no little labour and effort. the temple is supposed to have been surmounted by a colossal statue of the winged deity, visible from all parts of the surrounding country which was dedicated to his honour, and the foundations were only discovered a few years ago when excavating for the foundation of the observatory, which stands a little further on under the charge of professor janssen. on proceeding to the northern crest of the platform a wonderful view of the extinct craters and domes--about forty in number, and terminating in the puy de beauny, the most northerly member of the chain--is presented to the spectator. to the right is the vale of clermont and the rich valley of the allier merging into the great plain of central france. on the south side of the platform a no less remarkable spectacle meets the eye. the chain of puys and broken craters stretches away southwards for a distance of nearly ten miles, while the horizon is bounded in that direction by the lofty masses of the mont dore, cantal, and le puy ranges. nor does it require much effort of the imagination to restore the character of the region when these now dormant volcanoes were in full activity, projecting showers of ashes and stones high into the air amidst flames of fire and vast clouds of incandescent gas and steam. the material of which the puy de dôme is formed consists of a light grey, nearly white, soft felsitic lava, containing crystals of mica, hornblende, and specular iron-ore. it is highly vesicular, and was probably extruded in a pasty condition from a throat piercing the granitic plateau and the overlying sheet of ancient lava of mont dore. it has been suggested that such highly felsitic and acid lavas as that of which the puy de dôme, the grand sarcoui, and cliersou are composed, may have had their origin in the granite itself, melted and rendered viscous by intense heat. dr. e. gordon hull has suggested that the domite hills (owing to their low specific gravity) may have filled up pre-existing craters of ashes and scoriæ without rupturing them, as in the case of the heavier basaltic lavas, and then still continuing to be extruded, may have entirely enveloped them in its mass; so that each domite hill encloses within its interior a crater formed of ashes, stones, and scoriæ. in the case of the puy de dôme there is some evidence that the domite matter rests on a basis of ashes and scoriæ, which may be seen in a few places around the base of the cone. it is difficult without some such theory as this to explain how a viscous mass was able to raise mountains some or feet above the surrounding plain.[ ] (_j._) _sketch of the volcanic history of central france._--it now only remains to give a brief _resumé_ of the volcanic history of this region as it may be gathered from the relations of the rocks and strata to the volcanic products, and of these latter to each other. _ st stage._--it would appear that at the close of the eocene period great terrestrial changes occurred. the bed of the sea was converted into dry land, the strata were flexured and denuded, and a depression was formed in the granitic floor of central france, which, in the succeeding miocene period, was converted into an extensive lake peopled by molluscs, fishes, reptiles, and pachyderms of the period. _ nd stage._--towards the close of the miocene epoch volcanic eruptions commenced on a grand scale over the granitic platform in the districts now called mont dore, cantal, and the vivarais. vast sheets of trachytic and basaltic lavas successively invaded the tracts surrounding the central orifices of eruption, now constituting the more ancient of the lava-sheets of the auvergne region, and, invading the waters of the neighbouring lake, overspread the lacustrine deposits which were being accumulated therein. these volcanic eruptions probably continued throughout the pliocene period, interrupted by occasional intervals of inactivity, and ultimately altogether ceased. _ rd stage._--towards the close of the pliocene period terrestrial movements took place, owing to which the waters of the lake began to fall away, and the sheets of lava were subjected to great denudation. this process, probably accelerated by excessive rainfall during the succeeding post-pliocene and pluvial periods, was continued until plains and extensive river-valleys were eroded out of the sheets of lava and their supporting granitic rocks and the adjoining lacustrine strata. _ th stage._--a new outburst of volcanic forces marks this stage, during which the chain of the puy de dôme was thrown up on the west, and that of the newer cones of the vivarais on the south-east of the lacustrine tract. the waters of the lake were now completely drained away through the channel of the allier, and denudation, extending down to the present day, began over the area now forming the vale of clermont and adjoining districts. the volcanic action ultimately spent its force; and somewhere about the time of the appearance of man, the mammoth, rhinoceros, stag, and reindeer on the scene, eruptions entirely ceased, and gradually the region assumed those conditions of repose by which it is now physically characterised. [ ] the literature referring to this region is very extensive. guettard in , afterwards faujas, published descriptions of the rocks of the vivarais and velay; and desmarest's geological map, published in , is a work of great merit. the district was afterwards described by daubeny, lyell, von buch, and others; but by far the most complete work is that of scrope, entitled _volcanoes of central france_, containing maps and numerous illustrations, published in , and republished in a more extended form in ; to this i am largely indebted. [ ] a monument to pascal, erected by the citizens, occupies the centre of the square in clermont. it will be remembered that pascal verified the conclusions arrived at by torricelli regarding the pressure of the atmosphere, by carrying a torricellian tube to the summit of the puy de dôme, and recording how the mercury continually fell during the ascent, and rose as he descended. this experiment was made in . [ ] in this visit to auvergne in the summer of , the author was accompanied by his son, dr. e. gordon hull, and sir robert s. ball. on reaching the station at the summit of the ridge it seemed as if the volcanic fires had again been lighted, for the whole sky was aglow with the rays of the western sun. [ ] on the other hand, certain beds of ash and other volcanic _ejecta_ occur in _the uppermost_ strata of lake deposits of limagne, so that these may indicate the commencement of the period of eruption, as suggested further on. [ ] only very closely; for mr. scrope considers that the crater-cones of the chain of the haute loire give evidence of a somewhat earlier epoch of activity than those of the puy de dôme, as they have undergone a greater amount of subaerial erosion. [ ] the extent of this river erosion has been clearly brought out by scrope, and is admirably illustrated by several of his panoramic views, such as that in plate ix. of his work. [ ] scrope, _loc. cit._, p. . [ ] scrope, _loc. cit._, p. . [ ] scrope gives a view of these remarkable basaltic cliffs in plate xii. of his work, from which the above account is taken. at one spot near the village of le gua there is a break in the continuity of the sheet. [ ] see scrope, _loc. cit._, p. ; also appendix, p. . while there is no _primâ facie_ reason for questioning the origin of the demise skull, yet from what lyell states in his _antiquity of man_, p. , it will be seen that he found it impossible to identify its position, or to determine beyond question that its interment was due to natural causes. but assuming this to be the case, he shows how the individual to whom it belonged might have been enveloped in volcanic tuff or mud showered down during the final eruption of the volcano of demise. mm. hébert and lartet, on visiting the locality, also failed to find _in situ_ any exact counterpart of the stone now in the museum of le puy. [ ] see daubeny, _volcanoes_, p. . [ ] that is to say, the surfaces of the lava-streams are not at all, or only slightly, decomposed into soil suitable for the growth of plants, except in rare instances. [ ] e. g. hull, "on the domite mountains of central france," _scien. proc. roy. dublin society_, july , p. . dr. hull determined the density of the domite of the puy de dôme to be . , while that of lava is about . . chapter vii. the volcanic district of the rhine valley. the region bordering the rhine along both its banks above bonn, and extending thence along the valley of the moselle and into the eifel, has been the theatre of active volcanic phenomena down into recent times, but at the present day the volcanoes are dormant or extinct. (_a._) _geological structure._--the fundamental rocks of this region belong to the silurian, devonian, and carboniferous systems, consisting of schists, grits, and limestones, with occasional horizontal beds of miocene sandstone and shale with lignite, resting on the upturned edges of the older rocks. scattered over the greater part of the district here referred to are a number of conical eminences, often with craters, the bottoms of which are usually sunk much below the present level of the country, and thus receiving the surface drainage, have been converted into little lakes called "maars," differing from ordinary lakes by their circular form and the absence of any _apparent_ outlet for their waters.[ ] but before entering into details, it may be desirable to present the reader with a short outline of the physical history of the region (which has been ably done by dr. hibbert in his treatise, to which i have already referred), so as to enable him better to understand the succession of physical events in its volcanic history. [illustration: fig. .--sketch map to show the physical condition of the rhenish area in the miocene epoch.--(after hibbert.)] (_b._) _physical history._--from the wide distribution of stratified deposits of sand and clay at high levels on both banks of the rhine north of the moselle, it would appear that an extensive fresh-water basin, which dr. hibbert calls "the basin of neuwied," occupied a considerable tract on both banks, in the centre of which the present city of neuwied stands. this basin was bounded towards the south by the slopes of the hündsruck and taunus, which at the time here referred to formed a continuous chain of mountains. (fig. .) to the south of this chain lay the tertiary basin of mayence, which was connected at an early period--that of the miocene--with the waters of the ocean, as shown by the fact that the lower strata contain marine shells; these afterwards gave place to fresh-water conditions. the basin of neuwied was bounded towards the north by a ridge of devonian strata which extended across the present gorge of the rhine between andernach and linz, and to the north of this barrier lay another more extensive fresh-water basin, that of cologne. from this it will be seen that the rhine, as we now find it, had then only an infantile existence; in fact, its waters to the south of the hündsruck ridge drained away towards the south. but towards the commencement of the pliocene period the barriers of the hündsruck and taunus, as also that of the linz, were broken through, and the course of the waters was changed; and thus gradually, as the river deepened its bed, the waters were drained off from the great lakes.[ ] this rupture of the barriers may have been due, in the first instance, to the terrestrial disturbances accompanying the volcanic eruptions of the eifel and siebengebirge, though the erosion of the gorges at bingen and at linz to their present depth and dimensions is of course due to prolonged river action. it was about the epoch we have now arrived at--viz., the close of the miocene--that volcanic action burst forth in the region of the lower rhine. it is probable that this action commenced in the district of the siebengebirge, and afterwards extended into that of the moselle and the eifel, the volcanoes of which bear evidence of recent date. layers of trachytic tuff are interstratified with the deposits of sand, clay, and lignite of the formation known as that of the brown coal--of miocene age--which underlies nearly the whole of the volcanic district on both sides of the rhine near bonn,[ ] thus showing that volcanic action had already commenced in that part to some extent; but it does not appear from dr. hibbert's statement that any such fragments of eruptive rock are to be found in the strata which were deposited over the floor of the neuwied basin.[ ] it will be recollected that the epoch assigned for the earliest volcanic eruptions of auvergne was that here inferred for those of the lower rhine--viz., the close of the miocene stage--and from evidence subsequently to be adduced from other european districts, it will be found that there was a very widely spread outburst of volcanic action at this epoch. (_c._) _the range of the siebengebirge._--this range of hills--formed of the older volcanic rocks of the lower rhine--rises along the right bank of this noble river opposite bonn, where it leaves the narrow gorge which it traverses all the way from bingen, and opens out on the broad plain of northern germany. the range consists of a succession of conical hills sometimes flat-topped--as in the case of petersberg; and at the drachenfels, near the centre of the range it presents to the river a bold front of precipitous cliffs of trachyte porphyry. the sketch (fig. ) here presented was taken by the author in from the old extinct volcano of roderberg, and will convey, perhaps, a better idea of the character of this picturesque range than a description. the siebengebirge, although appearing as an isolated group of hills, is in reality an offshoot from the range of the westerwald, which is connected with another volcanic district of central germany known as the vogelsgebirge. the highest point in the range is attained in the lohrberg, which rises feet above the sea; the next, the great tränkeberg, feet; and the next, great oelberg, feet. [illustration: fig. .--the volcanic range of the siebengebirge, seen from the left bank of the rhine, above bonn.--(original.)] the range consists mainly of trachytic rocks--namely, trachyte-conglomerate, and solid trachyte, of which h. von dechen makes two varieties--that of the drachenfels, and that of the wolkenburg. but associated with these highly-silicated varieties of lava--and generally, if not always, of later date--are basaltic rocks which cap the hills of petersberg, nonnenstrom, gr. and ll. oelberg, gr. weilberg, and ober dollendorfer hardt. the question whether there is a transition from the one variety of volcanic rock into the other, or whether each belongs to a distinct and separate epoch of eruption, does not seem to be very clearly determined. mr. leonard horner states that it would be easy to form a suite of specimens showing a gradation from a white trachyte to a black basalt;[ ] but we must recollect that when mr. horner wrote, the microscopic examination of rocks by means of thin sections was not known or practised, and an examination by this process might have proved that this apparent transition is unreal. according to h. von dechen, there are sheets of basalt older than the greater mass of the brown coal formation, and others newer than the trachyte;[ ] while dykes of basalt traversing the trachytic lavas are not uncommon.[ ] the trachyte-conglomerate--which seems to be associated with the upper beds of the brown coal strata--is traversed by dykes of trachyte of later date; and though it is difficult to trace the line between the two varieties of this rock on the ground, dr. von rath has recognised the general distinction between them, which consists in the greater abundance of hornblende and mica in the trachyte of the wolkenburg than in that of the drachenfels. the trachyte of the drachenfels was probably the neck of a volcano which burst through the fundamental schists of the devonian period. it is remarkable for the large crystals of sanidine (glassy felspar) which it contains, and has a rude columnar structure. the absence of any clearly-defined craters of eruption, such as are to be found in the eifel district and on the left bank of the rhine--as, for example, in the case of the roderberg--may be regarded as sufficient evidence that this range is of comparatively high antiquity. it seems to bear the same relation to the more modern craters of the eifel and moselle that the mont dore and cantal volcanoes do to those of the puy de dôme. in both cases, denudation carried on throughout perhaps the pliocene and post-pliocene periods down to the present day has had the effect of demolishing the original craters; so that what we now observe as forming these ranges are the consolidated columns of original molten matter which filled the throats of the old volcanoes, or the sheets of lava which were extruded from them, but are now probably much reduced in size and extent. having thus given a description of the older volcanic range on the right bank of the rhine, we shall cross the river in search of some details regarding the more recent group of rhenish volcanoes, commencing with that of the roderberg, a remarkable hill a few miles south of bonn, from which the view of the seven mountains was taken. [illustration: fig. .--section of the extinct crater of the roderberg on the bank of the rhine, above bonn.--(original.)] (_d._) _the roderberg._--this crater, which was visited by the author in , is about one-fourth of a mile in diameter, and is in the form of a cup with gentle slopes on all sides. in its centre is a farmhouse surrounded by corn-fields. the general section through the hill is represented above (fig. ). the flanks on the north side are composed of loose quartzose gravel (gerolle), a remnant of the deposits formed around the margin of the "basin of neuwied" described above (p. ). this gravel is found covering the terraces of the brown coal formation several hundred feet above the rhine. besides quartz-pebbles, the deposit contains others of slate, grit, and volcanic rock. on reaching the edge of the crater we find the gravel covered over by black and purple scoria or slag the superposition of the scoria on the gravel being visible in several places, showing that the former is of more recent origin. on the opposite side of the crater, overlooking the rhine, we find the cliff of rolandsec composed of hard vesicular lava, rudely prismatic, and extending from the summit of the hill to its base, about feet below. this is the most northerly of the group of the eifel volcanoes. (_e._) _district of the rivers brühl and nette._--the volcanic region of the lower eifel, drained by these two principal streams which flow into the rhine, will amply repay exploration by the student of volcanic phenomena, owing to the variety of forms and conditions under which these present themselves within a small space. the fundamental rock is slate or grit of devonian age, furrowed by numerous valleys, often richly wooded, and diversified by conical hills of trachyte; or by crater-cones, formed of basalt or ashes, sometimes ruptured on one side, and occasionally sending forth streams of lava, as in the cases of the perlinkopf, the bausenberg, and the engelerkopf. the district attains its greatest altitude in the high acht (der hohe acht), an isolated cone of slate capped by basalt with olivine, and reaching a level of rhenish feet.[ ] (_f._) _the laacher see._--it would be impossible in a work of this kind to attempt a detailed description of the eifel volcanoes, often of a very complex character and obscure physical history, as in the case of the basin of rieden, where tufaceous deposits, trachytic and basaltic lavas and crater-cones, are confusedly intermingled, so that i shall confine my remarks to the deservedly famous district of the laacher see, which i had an opportunity of personally visiting some years since.[ ] [illustration: fig. .--plan and section of the laacher see, a lake on the borders of the eifel, occupying the crater of an old volcano.--g. gravel and volcanic sand forming banks of the lake and rim of old crater; l. sheet of trachytic lava with columnar structure; b. basaltic dyke; s. devonian slate, etc.] the laacher see is a lake of an oval form, over an english mile in the shorter diameter, and surrounded by high banks of volcanic sand, gravel, and scoriæ, except on the east side, where cliffs of clay-slate, in a nearly vertical position, and striking nearly e.w., may be observed. its depth from the surface of the water is feet.[ ] the ashes of the encircling banks contain blocks of slate and lava which have been torn from the sides of the orifice or neck of the volcano and blown into the air; and there can be no doubt that the ashes and volcanic gravel is the result of very recent eruptions. at the east side of the lake we find a stream of scoriaceous lava of a purple or reddish colour, highly vesicular, and containing crystals of mica; but the most important lava-stream is that which has taken a southerly direction from the crater of the laacher see towards nieder mendig and mayen, for a distance of about six miles. this great stream is covered throughout half its distance by beds of volcanic ash and lapilli, but emerges into the air at a distance of about two miles from the edge of the crater (see fig. ), and was formerly extensively quarried in underground caverns for millstones. here the rock is a vesicular trachyte, of a greyish colour, solidified in vertical columns of hexagonal form, about four feet in diameter, and traversed by transverse joint planes. these quarries have been worked from the time of the roman occupation of the country; and, before the introduction of iron or steel rollers for grinding corn, millstones were exported to all parts of europe and the british isles from this quarry.[ ] the district around the laacher see is covered by laminated _ejecta_ of the old volcano, probably of subaërial origin, through which bosses of the fundamental slate peer up at intervals, while the surface is diversified by several truncated cones. (_g._) _trass of the brühl valley._--the brühl valley, which unites with that of the rhine at the town of that name, and drains the northern side of the volcanic region, has always been regarded with much interest by travellers for the presence of a deposit of "trass" with which it is partially filled. the origin of this valley was pre-volcanic, as it is hewn out of the slaty rocks of the district. but at a later period it became filled with volcanic mud (tuffstein), out of which the stream has made for itself a fresh channel. the source of this mud is considered by hibbert[ ] to have been the old volcano of the lummerfeld, which, after becoming dormant, was filled with water, and thus became a lake. at a subsequent period, however, a fresh eruption took place near the edge of the lake, resulting in the remarkable ruptured crater known as the kunksköpfe, which rises about four miles to the north of the laacher see. the eruptions of this volcano appear to have displaced the mud of the lummerfeld, causing it to flow down into the deep gorge of the brühl, which it completely filled, as stated above. on walking down the valley one may sometimes see the junction of the tuff with the slate-rock which enfolds it. the tuff consists of white felspathic mud, with fragments of slate and lava, reaching a depth in some places of feet. after it has been quarried it is ground in mills, and used for cement stone under the name of _trass_. it is said to resemble the volcanic mud by which herculaneum was overwhelmed during the first eruption of vesuvius, and which was produced by the torrents of rain mixing with the ashes as they were blown out of the volcano. sufficient has probably now been written regarding the dormant, or recently extinct, volcanic districts of europe to give the reader a clear idea regarding their nature and physical structure. other districts might be added, such as those of central germany, hungary, transylvania, and styria; but to do so would be to exceed the proposed limits of this work; and we may therefore pass on to the consideration of the volcanic region of syria and palestine, which adjoins the mediterranean district we have considered in a former page. [ ] daubeny, _loc. cit._, p. . the geology of this region has had many investigators, of whom the chief are steininger, _erloschenen vulkane in der eifel_ ( ); hibbert, _extinct volcanoes of the basin of neuwied_, ; nöggerath, _das gebirge im rheinland_, etc., vols.; horner, "on the geology of bonn," _transactions of the geological society, london_, vol. iv. [ ] the views of dr. hibbert are not inconsistent with those of the late sir a. ramsay, on "the physical history of the valley of the rhine," _quart. jour. geol. soc._, vol. xxx. ( ). [ ] von dechen, _geog. beschreib. des siebengebirges am rhein_ (bonn, ). [ ] hibbert, _loc. cit._, p. . [ ] horner, "geology of environs of bonn," _transactions of the geological society_, vol. iv., new series. [ ] h. von dechen, _geog. führer in das siebengebirge am rhein_ (bonn, ). [ ] _ibid._, p. . [ ] dr. hibbert's work is illustrated by very carefully drawn and accurate views of some of the old cones and craters of this district, accompanied by detailed descriptions. [ ] the lava of schorenberg, near rieden, is interesting from the fact, stated by zirkel, that it contains leucite, nosean, and nephelin.--_die mikros. beschaf. d. miner. u. gesteine_, p. ( ). [ ] hibbert, _loc. cit._, p. . [ ] at the time of the author's visit the underground caverns, which are deliciously cool in summer, were used for the storage of the celebrated beer brewed by the moravians of neuwied. [ ] hibbert, _loc. cit._, p. . part iii. dormant or moribund volcanoes of other parts of the world. chapter i. dormant volcanoes of palestine and arabia. (_a._) _region east of the jordan and dead sea._--the remarkable line of country lying along the valley of the jordan, and extending into the great arabian desert, has been the seat of extensive volcanic action in prehistoric times. the specially volcanic region seems to be bounded by the depression of the jordan, the dead sea, and the arabah as far south as the gulf of akabah; for, although safed, lying at the head of the sea of galilee on the west of the jordan valley, is built on a basaltic sheet, and is in proximity to an extinct crater, its position is exceptional to the general arrangement of the volcanic products which may be traced at intervals from the base of hermon into central arabia, a distance of about miles.[ ] the tract referred to has been described at intervals by several authors, of whom g. schumacher,[ ] l. lartet,[ ] canon tristram,[ ] m. niebuhr,[ ] and c. m. doughty[ ] may be specially mentioned in this connection. the most extensive manifestations of volcanic energy throughout this long tract of country appear to be concentrated at its extreme limits. at the northern extremity the generally wild and rugged tract of the jaulân and haurân, called in the bible _trachonitis_, and still farther to the eastward the plateau of the lejah, with its row of volcanic peaks sloping down to the vast level of bashan, is covered throughout nearly its whole extent by great sheets of basaltic lava, above which rise at intervals, and in very perfect form, the old crater-cones of eruption. a similar group of extinct craters with lava-flows has been described and figured by a recent traveller, mr. c. m. doughty, in parts of central arabia. the general resemblance of these arabian volcanoes to those of the jaulân is unquestionable; and as they are connected with each other by sheets of basaltic lava at intervals throughout the land of moab, it is tolerably certain that the volcanoes lying at either end of the chain belong to one system, and were contemporaneously in a state of activity. (_b._) _geological conditions._--before entering any further into particulars regarding the volcanic phenomena of this region, it may be desirable to give a short account of its geological structure, and the physical conditions amongst which the igneous eruptions were developed. down to the close of the eocene period the whole region now under consideration was occupied by the waters of the ocean. the mountains of sinai were islands in this ocean, which had a very wide range over parts of asia, africa, and europe. but at the commencement of the succeeding miocene stage the crust was subjected to lateral contraction, owing to which the ocean bed was upraised. the strata were flexured, folded, and often faulted and fissured along lines ranging north and south, the great fault of the jordan-arabah valley being the most important. at this period the mountains of the lebanon, the table-lands of judæa and of arabia, formed of limestone, previously constituting the bed of the ocean during the eocene and cretaceous periods, were converted into land surfaces. along with this upheaval of the sea-bed there was extensive denudation and erosion of the strata, so that valleys were eroded over the subaërial tracts, and the jordan-arabah valley received its primary form and outline. up to this time there does not appear to have been any outbreak of volcanic forces; but with the succeeding pliocene period these came into play, and eruptions of basaltic lava took place along rents and fissures in the strata, while craters and cones of slag, scoriæ, and ashes were thrown up over the region lying to the east of the sea of galilee and the sources of the jordan on the one hand, and the central parts of the great arabian desert on the other. these eruptions, probably intermittent, continued into the succeeding glacial or pluvial period, and only died out about the time that the earliest inhabitants appeared on the scene. (_c._) _the jaulân and haurân._--this tract is bounded by the valley of the jordan and the sea of galilee on the west, from which it rises by steep and rocky declivities into an elevated table-land, drained by the yarmûk (hieromax), the nahr er rukkâd, and other streams, which flow westwards into the jordan along deep channels in which the basaltic sheets and underlying limestone strata are well laid open to view. on consideration it seems improbable that the great sheets of augitic lava, such as cover the surface of the land of bashan, are altogether the product of the volcanic mountains which appear to be confined to special districts in this wide area. some of the craters do indeed send forth visible lava-streams, but they are insignificant as compared with the general mass of the plateau-basalts; and the crater-cones themselves appear in some cases to be posterior to the platforms of basalt from which they rise. it is very probable, therefore, that the lavas of this region have, in the main, been extruded from fissures of eruption at an early period, and spread over the surface of the country in the same manner as those of the snake river region, and the borders of the pacific ocean of north america, and possibly of the antrim plateau in ireland, afterwards to be described. the volcanic hills which rise above the plateau are described in detail by schumacher. of these, tell abû nedîr is the largest in the jaulân. it reaches an elevation of feet above the mediterranean sea, and feet above the plain from which it rises; the circumference of its base is three miles, and the rim of the crater itself, which is oval in form, is yards in its larger diameter. the interior is cultivated by circassians, and is very fruitful; the walls descend at an angle of about ° on the inside, the exterior slope of the mountain being about °. the cone seems to be formed chiefly of scoriæ, and the lava-stream, which issues forth from the interior, forms a frightfully stony and lacerated district.[ ] [illustration: fig. .--extinct craters in the jaulân, north-east from the sea of galilee, called tell abû en nedâ and tell el urâm, with a central cone.--(after schumacher.)] another remarkable volcano is the tell abû en nedâ (fig. ). this is a double crater, with a cone (probably of cinders) rising from the interior of one of them. the highest point of the rim of one of the craters reaches a level of feet above the sea. a lava-stream issues forth from abû en nedâ, and unites with another from a neighbouring volcano. tell el ahmâr is a ruptured crater of imposing aspect, reaching an elevation of feet, and sending forth a lava-current, which falls in regular terraces from the outlet towards the west and north. the ruptured crater of tell el akkasheh, which reaches a height of feet, has a less forbidding aspect than the greater number of the extinct volcanoes of this region, owing to the fact that its sides are covered by oaks, which attain to magnificent proportions along the summit. numerous other volcanic hills occur in this district, but the most remarkable is that called tell el farras (the hill of the horse). it is an isolated mountain, visible from afar, and reaches an elevation of feet, or nearly feet above the surrounding plain. the oval crater of this volcano opens towards the north, and has a depth of feet below the edge, with moderately steep sloping sides ( °- °), while the slope of the exterior, at first steep, gradually lessens to °- °. these slopes are covered with reddish or yellowish slag. the above examples will probably suffice to afford the reader a general idea of the size and form of the volcanoes in this little known region. it has been stated above that the great lava-floods have probably been poured forth intermittently. the statement receives confirmation from the observations of canon tristram, made in the valley of the yarmûk.[ ] this impetuous torrent rushes down a gorge, sometimes having limestone on one side and a wall of basalt on the other. this is due to the fact that the river channel had been eroded before the volcanic eruptions had commenced; but on the lava-stream reaching the channel, it naturally descended towards the valley of the jordan along its bed, displacing the river, or converting it into clouds of steam. subsequently the river again hewed out its channel, sometimes in the lava, sometimes between this rock and the chalky limestone. but, in addition to this, it has been observed that there is a bed of river gravel interposed between two sheets of basalt in the yarmûk ravine; showing that after the first flow of that molten rock the river reoccupied its channel, which was afterwards invaded by another molten lava-stream, into which the waters have again furrowed the channel which they now occupy. the basaltic sheets descend under the waters of the sea of galilee on the east side, and were probably connected with those of safed, crossing the jordan valley north of that lake; owing to this the waters of the lake of merom (huleh) were pent up, and formerly covered an extensive tract, now formed of alluvial deposits. (_d._) _land of moab._--proceeding southwards into the land of moab, the volcanic phenomena are here of great interest. extensive sheets of basaltic lava, described as far back as by seetzen, and more recently by lartet and tristram, are found at intervals between the wâdies mojib (arnon) and haidan. on either side of the mojib, cliffs of columnar basalt are seen capping the beds of white cretaceous limestone, while a large mass has descended into the w. haidan between cliffs of limestone and marl on either hand. around jebel attarus--a dome-shaped hill of limestone--a sheet of basaltic lava has been poured, and has descended the deep gorge of the zerka maïn, which enters the dead sea some feet below. this gorge had been eroded before the basaltic eruption, so that the stream of molten lava took its course down the bed of this stream to the water's edge, and grand sections have been laid bare by subsequent erosion along the banks. pentagonal columns of black basalt form perpendicular walls, first on one side, then on the other; while considerable masses of scoriæ, peperino, and breccia appear at the head of the glen, probably marking the orifice of eruption. other eruptions of basalt occur, one at mountar ez zara, to the south of zerka maïn, and another at wady ghuweir, near the north-eastern end of the dead sea. there are no lava-streams on the western side of the ghor, or of the dead sea.[ ] the outburst of the celebrated thermal springs of callirrhoë, together with nine or ten others, along the channel of the zerka maïn, is a circumstance which cannot be dissociated from the occurrence of basaltic lava at this spot. in a reach of three miles, according to tristram, there are ten principal springs, of which the fifth in descent is the largest; but the seventh and eighth, about half a mile lower down, are the most remarkable, giving forth large supplies of sulphurous water. the tenth and last is the hottest of all, indicating a temperature of ° fahr. thus it would appear that the heat increases with the depth from the upper surface of the table-land; a result which might be expected, supposing the heated volcanic rocks to be themselves the source of the high temperature. to a similar cause may be attributed the hot-springs of hammath, near tiberias, and those of the yarmûk near its confluence with the jordan. some of these and other springs break out along, or near, the line of the great jordan-arabah fault which ranges throughout the whole extent of this depression, from the base of hermon to the gulf of akabah, generally keeping close to the eastern margin of the valley. (_e._) _the arabian desert._--the basaltic lava-floods occupy a very large extent of the arabian desert, from el hisma (lat. ° ' n.) to the neighbourhood of mecca on the south, a distance of about miles, with occasional intervals. the lava-sheets are called "harras" (or "harrat"), one of which, harrat sfeina, terminates about ten miles north of mecca. the lava-sheets rest sometimes on the red sandstone, at other times, on the granite and other crystalline rocks of great geological antiquity. in addition to the sheets of basalt, numerous crater-cones rise from the basaltic platform at a level of feet above the sea, and two volcanic mountains, rising far to the west of the principal range, called respectively harrât jeheyma and h. rodwa, almost overlook the coast of the red sea.[ ] (_f._) _age of the volcanic eruptions._--it is very clear that the first eruptions, producing the great basaltic sheets of moab and arabia, occurred after the principal features of the country had been developed. the depression of the jordan-arabah valley, the elevation of the eastern side of this valley along the great fault line, and the channels of the principal tributary streams, such as those of the yarmûk and zerka maïn, all these had been eroded out before they were invaded by the molten streams of lava. now, as these physical features were developed and sculptured out during the miocene period, as i have elsewhere shown to be the case,[ ] we may with great probability refer the volcanic eruptions to the geological epoch following--namely, the pliocene. how far downwards towards the historic period the eruptions continued is not so certain. dr. daubeny, quoting several passages from the old testament prophets,[ ] says it might be inferred that volcanoes were in activity even so late as to admit of their being included within the limits of authentic history. the poetic language and imagery used in these passages by the prophets certainly lends a probability to this view, but nothing more. on the other hand, these regions have suffered through many centuries from the secondary effects of seismic action and subterranean forces, and earthquake shocks have laid in ruins the great temples and palaces of palmyra, baalbec, and other cities of antiquity. the same uncertainty regarding the time at which volcanic action died out, with reference to the appearance of man on the scene, hangs over the region of arabia and syria, as we have seen to be the case in reference to the extinct volcanoes of auvergne, the eifel, and the lower rhine. in all these cases the commencement and close of eruptive action appear to have been very much about the same period--namely, the miocene period on the one hand, and that at which man entered upon the scene on the other; but in the case of syria and western palestine, the close of the volcanic period may have been somewhat more than b.c. [ ] lake phiala, near the lake of huleh, is also situated to the west of the jordan valley. its origin, according to tristram, is volcanic. [ ] schumacher, "the jaulân," _quarterly statement of the palestine exploration fund_, and ; and _across the jordan_, london, . [ ] lartet, _voyage d'exploration de la mer morte_ (géologie), paris, . [ ] tristram, _land of moab_, london, ; and _land of israel_, . [ ] niebuhr, _beschreibung von arabien_, . [ ] c. m. doughty, _arabia deserta_, vols., . a generalised account of this volcanic region by the author will be found in the "memoir on the physical geology of arabia petræa, and palestine," _palestine exploration fund_, . [ ] schumacher, _loc. cit._, p. . [ ] _land of israel_, p. . [ ] "geology of arabia petræa, and palestine," _memoirs of the palestine exploration fund_, p. . [ ] doughty, _loc. cit._, vol. i., plate vi., p. . an excellent geological sketch map accompanies this work. [ ] "memoir of the geology of arabia petræa, and palestine," chap. vi. p. . [ ] nahum, i. , ; micah, i. , ; isaiah, lxiv. - ; jeremiah, l. . chapter ii. the volcanic regions of north america. (_a._) _contrast between the eastern and western regions._--in no point is there a more remarkable contrast between the physical structure of eastern and western america than in the absence of volcanic phenomena in the former and their prodigious development in the latter. the great valley of the mississippi and its tributaries forms the dividing territory between the volcanic and non-volcanic areas; so that on crossing the high ridges in which the western tributaries of america's greatest river have their sources, and to which the name of the "rocky mountains" more properly belongs, we find ourselves in a region which, throughout the later tertiary times down almost to the present day, has been the scene of volcanic operations on the grandest scale; where lava-floods have been poured over the country through thousands of square miles, and where volcanic cones, vying in magnitude with those of etna, vesuvius, or hecla, have established themselves. this region, generally known as "the great basin," is bounded on the west by the "pacific range" of mountains, and includes portions of new mexico, arizona, california, nevada, utah, colorado, idaho, oregon, wyoming, montana, and washington. to the south it passes into the mountainous region of mexico, also highly volcanic; and thence into the ridge of panama and the andes. it cannot be questioned but that the volcanic nature of the great basin is due to the same causes which have originated the volcanic outbursts of the andes; but, from whatever cause, the volcanic forces have here entered upon their secondary or moribund stage. in the yellowstone valley, geysers, hot springs, and fumaroles give evidence of this condition. in other districts the lava-streams are so fresh and unweathered as to suggest that they had been erupted only a few hundred years ago; but no active vent or crater is to be found over the whole of this wide region. a few special districts only can here be selected by way of illustration of its special features in connection with its volcanic history. (_b._) _the plateau country of utah and arizona._--this tract, which is drained by the colorado river and its tributaries, is bounded on the north by the wahsatch range, and extends eastwards to the base of the sierra nevada. round its margin extensive volcanic tracts are to be found, with numerous peaks and truncated cones--the ancient craters of eruption--of which mount san francisco is the culminating eminence. south of the wahsatch, and occupying the high plateaux of utah, enormous masses of volcanic products have been spread over an area of square miles, attaining a thickness of between and feet. the earlier of these great lava-floods appear to have been trachytic, but the later basaltic; and in the opinion of captain dutton, who has described them, they range in point of time from the middle tertiary (miocene) down to comparatively recent times. (_c._) _the grand cañon._--to the south of the high plateaux of utah are many minor volcanic mountains, now extinct; and as we descend towards the grand cañon of colorado we find numerous cinder-cones scattered about at intervals near the cliffs.[ ] extensive lava-fields, surmounted by cinder-cones, occupy the plateau on the western side of the grand cañon; and, according to dutton, the great sheets of basaltic lava, of very recent age, which occupy many hundred square miles of desert, have had their sources in these cones of eruption.[ ] crossing to the east of the grand cañon, we find other lava-floods poured over the country at intervals, surmounted by san francisco--a volcanic mountain of the first magnitude--which reaches an elevation, according to wheeler, of , feet above the ocean. it has long been extinct, and its summit and flanks are covered with snow-fields and glaciers. other parts of arizona are overspread by sheets of basaltic lava, through which old "necks" of eruption, formed of more solid lava than the sheets, rise occasionally above the surface, and are prominent features in the landscape. further to the eastward in new mexico, and near the margin of the volcanic region, is another volcanic mountain little less lofty than san francisco, called mount taylor, which, according to dutton, rises to an elevation of , feet above the ocean, and feet above the general level of the surrounding plateau of lava. this mountain forms the culminating point of a wide volcanic tract, over which are distributed numberless vents of eruption. scores of such vents--generally cinder-cones--are visible in every part of the plateau, and always in a more or less dilapidated condition.[ ] mount taylor is a volcano, with a central pipe terminating in a large crater, the wall of which was broken down on the east side in the later stage of its history. [illustration: fig. .--mount shasta ( , feet), a snow-clad volcanic cone in california, with mount shastina, a secondary crater, on the right; the valley between is filled with glacier-ice.--(after dutton).] (_d._) _california._--proceeding westwards into california, we are again confronted with volcanic phenomena on a stupendous scale. the coast range of mountains, which branches off from the sierra nevada at mount pinos, on the south, is terminated near the northern extremity of the state by a very lofty mountain of volcanic origin, called mount shasta, which attains an elevation of , feet (see fig. ). this mountain was first ascended by clarence king in ,[ ] and although forming, as it were, a portion of the pacific coast range, it really rises from the plain in solitary grandeur, its summit covered by snow, and originating several fine glaciers. the summit of mount shasta is a nearly perfect cone, but from its north-west side there juts out a large crater-cone just below the snow-line, between which and the main mass of the mountain there exists a deep depression filled with glacier ice. this secondary crater-cone has been named mount shastina, and round its inner side the stream of glacier ice winds itself, sometimes surmounting the rim of the crater, and shooting down masses of ice into the great caldron. the length of this glacier is about three miles, and its breadth about feet. another very lofty volcanic mountain is mount rainier, in the washington territory, consisting of three peaks of which the eastern possesses a crater very perfect throughout its entire circumference. this mountain appears to be formed mainly of trachytic matter. proceeding further north into british territory, several volcanic mountains near the pacific coast are said to exhibit evidence of activity. of these may be mentioned mount edgecombe, in lat. °. ; mount fairweather, lat. °. which rises to a height of , feet; and mount st. elias, lat. °. , just within the divisional line between british and russian territory, and reaching an altitude of , feet. this, the loftiest of all the volcanoes of the north american continent, except those of mexico, may be considered as the connecting link in the volcanic chain between the continent and the aleutian islands.[ ] (_e._) _lake bonneville._--returning to utah we are brought into contact with phenomena of special interest, owing to the inter-relations of volcanic and lacustrine conditions which once prevailed over large tracts of that territory. the present great salt lake, and the smaller neighbouring lakes, those called utah and sevier, are but remnants of an originally far greater expanse of inland water, the boundaries of which have been traced out by mr. c. k. gilbert, and described under the name of lake bonneville.[ ] the waters of this lake appear to have reached their highest level at the period of maximum cold of the post-pliocene period, when the glaciers descended to its margin, and large streams of glacier water were poured into it. eruptions of basaltic lava from successive craters appear to have gone on before, during, and after the lacustrine epochs; and the drying up of the waters over the greater extent of their original area, now converted into the sevier desert, and their concentration into their present comparatively narrow basins, appears to have proceeded _pari passu_ with the gradual extinction of the volcanic outbursts. two successive epochs of eruption of basalt appear to have been clearly established--an earlier one of the "provo age," when the lava was extruded from the tabernacle craters, and a later epoch, when the eruptions took place from the ice spring craters. the oldest volcanic rock appears to be rhyolite, which peers up in two small hills almost smothered beneath the lake deposits. its eruption was long anterior to the lake period. on the other hand, the cessation of the eruptions of the later basaltic sheets is evidently an event of such recent date that mr. gilbert is led to look forward to their resumption at some future, but not distant, epoch. as he truly observes, we are not to infer that, because the outward manifestations of volcanic action have ceased, the internal causes of those manifestations have passed away. these are still in operation, and must make themselves felt when the internal forces have recovered their exhausted energies; but perhaps not to the same extent as before. (_f._) _region of the snake river._--the tract of country bordering the snake river in idaho and washington is remarkable for the vast sheets of plateau-basalt with which it is overspread, extending sometimes in one great flood farther than the eye can reach, and what is still more remarkable, they are often unaccompanied by any visible craters or vents of eruption. in oregon the plateau-basalt is at least , feet in thickness, and where traversed by the columbia river it reaches a thickness of about , feet. the snake and columbia rivers are lined by walls of volcanic rock, basaltic above, trachytic below, for a distance of, in the former, one hundred, in the latter, two hundred, miles. captain dutton, in describing the high plateau of utah, observes that the lavas appear to have welled up in mighty floods without any of that explosive violence generally characteristic of volcanic action. this extravasated matter has spread over wide fields, deluging the surrounding country like a tide in a bay, and overflowing all inequalities. here also we have evidence of older volcanic cones buried beneath seas of lava subsequently extruded. (_g._) _fissures of eruption._--the absence, or rarity, of volcanic craters or cones of eruption in the neighbourhood of these great sheets has led american geologists to the conclusion that the lavas were in many cases extruded from fissures in the earth's crust rather than from ordinary craters.[ ] this view is also urged by sir a. geikie, who visited the utah region of the snake river in , and has vividly described the impression produced by the sight of these vast fields of basaltic lava. he says, "we found that the older trachytic lavas of the hills had been deeply trenched by the lateral valleys, and that all these valleys had a floor of black basalt that had been poured out as the last of the molten materials from the now extinct volcanoes. there were no visible cones or vents from which these floods of basalt could have proceeded. we rode for hours by the margin of a vast plain of basalt stretching southward and westward as far as the eye could reach.... i realised the truth of an assertion made first by richthofen,[ ] that our modern volcanoes, such as vesuvius and etna, present us with by no means the grandest type of volcanic action, but rather belong to a time of failing activity. there have been periods of tremendous volcanic energy, when instead of escaping from a local vent, like a vesuvian cone, the lava has found its way to the surface by innumerable fissures opened for it in the solid crust of the globe over thousands of square miles."[ ] (_h._) _volcanic history of western america._--the general succession of volcanic events throughout the region of western america appears to have been somewhat as follows:--[ ] the earliest volcanic eruptions occurred in the later eocene epoch and were continued into the succeeding miocene stage. these consisted of rocks moderately rich in silica, and are grouped under the heads of propylite and andesite. to these succeeded during the pliocene epoch still more highly silicated rocks of trachytic type, consisting of sanidine and oligoclase trachytes. then came eruptions of rhyolite during the later pliocene and pleistocene epochs; and lastly, after a period of cessation, during which the rocks just described were greatly eroded, came the great eruptions of basaltic lava, deluging the plains, winding round the cones or plateaux of the older lavas, descending into the river valleys and flooding the lake beds, issuing forth from both vents and fissures, and continuing intermittently down almost into the present day--certainly into the period of man's appearance on the scene. thus the volcanic history of western america corresponds remarkably to that of the european regions with which we have previously dealt, both as regards the succession of the various lavas and the epochs of their eruption. (_i._) _the yellowstone park._--the geysers and hot springs of the yellowstone park, like those in iceland and new zealand, are special manifestations of volcanic action, generally in its secondary or moribund stage. the geysers of the yellowstone occur on a grand scale; the eruptions are frequent, and the water is projected into the air to a height of over feet. most of these are intermittent, like the remarkable one known as old faithful, the castle geyser, and the giantess geyser described by dr. hayden, which ejects the water to a height of feet. the geyser-waters hold large quantities of silica and sulphur in solution, owing to their high temperature under great pressure, and these minerals are precipitated upon the cooling of the waters in the air, and form circular basins, often gorgeously tinted with red and yellow colours.[ ] [ ] j. w. powell, _exploration of the cañons of the colorado_, pp. , . major powell describes a fault or fissure through which floods of lava have been forced up from beneath and have been poured over the surface. many cinder-cones are planted along the line of this fissure. [ ] capt. c. e. dutton. _sixth ann. rep. u.s. geol. survey_, - . [ ] dutton, _loc. cit._, chap. iv. p. . [ ] _amer. jour. science_, vol. ., ser. ( ). a beautiful map of this mountain is given in the _fifth annual report, u.s. geol. survey_, - . plate . [ ] daubeny, _loc. cit._, p. . [ ] gilbert, _monograph u.s. geol. survey_, vol. i. ( ). [ ] powell, _exploration of the colorado river_, p. , etc. ( ). hayden, _rep. u.s. geol. survey of the colorado, etc._ ( - ). [ ] richthofen, _natural system of volcanic rocks_, mem. california acad. sciences, vol. i. ( ). [ ] geikie, _geological sketches at home and abroad_, p. ( ). [ ] prestwich, _geology_, vol. i. p. , quoting from richthofen. [ ] the origin of geysers is variously explained; see prestwich, _geology_, vol. i. p. . they are probably due to heated waters suddenly converted into steam by contact with rock at a high temperature. chapter iii. volcanoes of new zealand. one other region of volcanic action remains to be noticed before passing on to the consideration of those of less recent age. new zealand is an island wherein seem to be concentrated all the phenomena of volcanic action of past and present time. though it is doubtful if the term "active," in its full sense, can be applied to any of the existing craters (with two or three exceptions, such as tongariro and whakari island), we find craters and cones in great numbers in perfectly fresh condition, extensive sheets of trachytic and basaltic lavas, ashes, and agglomerates; lava-floods descending from the ruptured craters of ashes and scoriæ; old crater-basins converted into lakes; geysers, hot springs and fumaroles which may be counted by hundreds, and cataracts breaking over barriers of siliceous sinter; and, lastly, lofty volcanic mountains vying in magnitude with vesuvius and etna. all these wonderful exhibitions of moribund volcanic action seem to be concentrated in the northern island of auckland. the southern island, which is the larger, also has its natural attractions, but they are of a different kind; chief of all is the grand range of mountains called, not inappropriately, the "southern alps," vying with its european representative in the loftiness of its peaks and the splendour of its snowfields and glaciers, but formed of more ancient and solid rocks than those of the northern island. (_a._) _auckland district._--we are indebted to several naturalists for our knowledge of the volcanic regions of new zealand, but chiefly to ferdinand von hochstetter, whose beautiful maps and graphic descriptions leave nothing to be desired.[ ] in this work hochstetter was assisted by julius haast and sir j. hector. from their account we learn that the isthmus of auckland is one of the most remarkable volcanic districts in the world. it is characterised by a large number of extinct cinder-cones, in a greater or less perfect state of preservation, and giving origin to lava-streams which have poured down the sides of the hills on to the plains. besides these are others formed of stratified tuff, with interior craters, surrounding in mural cliffs eruptive cones of scoriæ, ashes, and lapilli; these cones are scattered over the isthmus and shores of waitemata and manukau. the tuff cones and craters rise from a floor of tertiary sandstone and shale, the horizontal strata of which are laid open in the precipitous bluffs of waitemata and manukau harbours; they sometimes contain fossil shells of the genera _pecten_, _nucula_, _cardium_, _turbo_, and _neritæ_. as the volcanic tuff-beds are intermingled with the upper tertiary strata, it is inferred that the first outbursts of volcanic forces occurred when the region was still beneath the waters of the ocean. cross-sections show that the different layers slope both outwards (parallel to the sides) and inwards towards the bottom of the craters. sometimes these craters have been converted into lakes, as in the case of those of the eifel; but generally they are dry or have a floor of morass. of the crater-lakes, those of kohuora, five in number, are perhaps the most remarkable; and in the case of two of these the central cones of slag appear as islets rising from the surface of the waters. the fresh-water lake pupuka has a depth of twenty-eight fathoms. to the north of auckland harbour rises out of the waters of the hauraki gulf the cone of rangitoto, feet high, the flanks formed of rugged streams of basalt, and the summit crowned by a circular crater of slag and ash, out of the centre of which rises a second cone with the vent of eruption. this is the largest and newest of the auckland volcanoes, and appears to have been built up by successive outpourings of basaltic lava from the central orifice, after the general elevation of the island. [illustration: fig. .--forms of volcanic tuff cones, with their cross-sections, in the province of auckland.--no. . simple tuff cone with central crater; no. . outer tuff cone with interior cinder cone and crater; no. . the same with lava-stream issuing from the interior cone.--(after hochstetter.)] before leaving the description of the tuff-cones, which are a peculiar feature in the volcanic phenomena of new zealand, and are of many forms and varieties, we must refer to that of mount wellington (maunga rei). this is a compound volcano, in which the oldest and smallest of the group is a tuff-crater-cone, exhibiting very beautifully the outward slope of its beds. within this crater arise two cones of cinders, each with small craters. it would appear that after a long interval the larger of the two principal cones, formed of cinders and known as mount wellington, burst forth from the southern margin of the older tuff-cone, and, being built up to a height of feet, gradually overspread the sides of its older neighbour. mount wellington itself has three craters, and from these large streams of basaltic lava have issued forth in a westerly direction, while a branch entered and partially filled the old tuff-crater to the northwards. southwards from manukau harbour, and extending a short distance from the coast-line to taranaki point, there occurs a plateau of basalt-conglomerate (_basaltkonglomerat_), with sheets of basaltic lava overspreading the tertiary strata. these plateau-basalts are intersected by eruptive masses in the form of dykes, but still there are no craters or cones of eruption to be seen; so that we may infer that the sheets, at least, were extruded from fissures in the manner of those of the colorado or idaho regions of america. proceeding still further south into the interior of the island, we here find a lofty plateau of an average elevation of , feet, interposed between the tertiary beds of the upper and middle waikato, and formed of trachytic and pitch-stone tuff, amongst which arise old extinct volcanic cones, such as those of karioi, pirongia, kakepuku, maunga tautari, aroha, and many others. these trachytic lavas would seem to be more ancient than the basaltic, previously described. (_b._) _taupo lake, and surrounding district._--but of all these volcanic districts, none is more remarkable than that surrounding the taupo lake, which lies amidst the tertiary strata of the upper waikato basin. the surface of this lake is , feet above that of the ocean, and its margin is enclosed within a border of rhyolite and pitchstone--rising into a mass of the same material , feet high on the eastern side. the form of the lake does not suggest that it is itself the crater of a volcano, but rather that it was originated by subsidence. on all sides, however, trachytic cones arise, of which the most remarkable group lies to the south of the lake, just in front of the two giant trachytic cones, the loftiest in new zealand, one called tongariro, rising about , feet, and the other ruapahu, which attains an elevation of over , feet, with the summit capped by snow. these two lofty cones, standing side by side, are supposed by the maoris to be the husband and wife to whom were born the group of smaller cones above referred to as occupying the southern shore of taupo lake. the volcano of tongariro may still be considered as in a state of activity, as its two craters (ngauruhoe and ketetahi) constantly emit steam, and several solfataras break out on its flanks.[ ] (_c._) _roto mahana._--in a northerly direction from tongariro, and distant from the coast by a few miles, lies in the bay of plenty the second of the active volcanoes of new zealand, the volcanic island of whakari (white island), from the crater of which are constantly erupted vast masses of steam clouds. the distance between these two active craters is nautical miles; and along the tract joining them steam-jets and geysers issue forth from the deep fissures through which the lava sheets have formerly been extruded. numerous lakes also occupy the larger cavities in the ground; and hot-springs, steam-fumaroles and solfataras burst out in great numbers along the banks of the roto mahana lake and the kaiwaka river by which it is drained. amongst such eruptions of hot-water and steam we might expect the formation of siliceous sinter, and the deposition of sulphur and other minerals; nor will our expectations be disappointed. for here we have the wonderful terraces of siliceous sinter deposited by the waters entering roto mahana as they descend from the numerous hot-springs or pools near its margin. all travellers concur in describing these terraces as the most wonderful of all the wonders of the lake district of new zealand--so great is their extent, and so rich and varied is their colouring. the beautiful map of roto mahana on an enlarged scale by hochstetter shows no fewer than ten large sinter terraces descending towards the margin of this lake, besides several mud-springs, fumaroles, and solfataras. but the largest and most celebrated of all the sinter terraces has within the last few years been buried from view beneath a flood of volcanic trass, or mud, an event which was as unexpected as it was unwelcome. in may, , the mountain of tarawera, which rises to the north-east of roto mahana, and on the line of eruption above described, suddenly burst forth into violent activity, covering the country for miles around with clouds of ashes, and, pouring down torrents of mud, completely enveloped the beautiful terrace of sinter which had previously been one of the wonders of new zealand. by the same eruption several human beings were entombed, and their residences destroyed. the waters of roto mahana, together with the hot-springs and fountains are fed from rain, and from the waters of taupo lake, which, sinking through fissures in the ground, come in contact with the interior heated matter, and thus steam at high temperature and pressure is generated.[ ] (_d._) _moribund condition of new zealand volcanoes._--from what has been said, it will be inferred that in the case of new zealand, as in those of auvergne, the eifel and lower rhine, arabia, and western america, we have an example of a region wherein the volcanic forces are well-nigh spent, but in which they were in a state of extraordinary activity throughout the later tertiary, down to the commencement of the present epoch. in most of these cases the secondary phenomena of vulcanicity are abundantly manifest; but the great exhibitions of igneous action, when the plains were devastated by sheets of lava, and cones and craters were piled up through hundreds and thousands of feet, have for the present, at least, passed away. [ ] _geol.-topographischer atlas von neu-seeland_, von dr. ferd. von hochstetter und dr. a. petermann. gotha: justus perthes ( ). also _new zealand_, trans. by e. sauter, stuttgart ( ). [ ] tongariro was visited in by mr. h. dyson, who describes the eruption of steam. [ ] mr. froude figures and describes the two terraces, the "white" and "pink," in _oceana_, nd edition, pp. - . part iv. tertiary volcanic districts of the british isles. chapter i. antrim. it is an easy transition to pass from the consideration of european and other dormant, or extinct, volcanic regions to those of the british isles, though the volcanic forces may have become in this latter instance quiescent for a somewhat longer period. in all the cases we have been considering, whether those of central italy, of the rhine and moselle, of auvergne, or of syria and arabia, the cones and craters of eruption are generally present entire, or but slightly modified in form and size by the effects of time. but in the case of the tertiary volcanic districts of the british isles this is not so. on the contrary, these more prominent features of vulcanicity over the surface of the ground have been removed by the agents of denudation, and our observations are confined to the phenomena presented by extensive sheets of lava and beds of ash, or the stumps and necks of former vents of eruption, together with dykes of trap by which the plateau-lavas are everywhere traversed or intersected. the volcanic region of the british isles extends at intervals from the north-east of ireland through the island of mull and adjoining districts on the mainland of morvern and ardnamurchan into the isle of skye, and comprises several smaller islets; the whole being included in the general name of the inner hebrides. it is doubtful if the volcanic lavas of co. antrim were ever physically connected with those of the west of scotland, though they may be considered as contemporary with them; and in all cases the existing tracts of volcanic rock are mere fragments of those originally formed by the extrusion of lavas from vents of eruption. in addition to these, there are large areas of volcanic rock overspread by the waters of the ocean. (_a._) _geological age._--the british volcanic eruptions now under consideration are all later than the cretaceous period. throughout antrim, and in parts of mull, the lavas are found resting on highly eroded faces either of the upper chalk (fig. ), or, where it has been altogether denuded away, on still older mesozoic strata. from the relations of the basaltic sheets of antrim to the upper chalk, it is clear that the latter formation, after its deposition beneath the waters of the cretaceous seas, was elevated into dry land and exposed to a long period of subaërial erosion before the first sheets of lava invaded the surface of the ground. we are, therefore, tolerably safe in considering the first eruptions to belong to the tertiary period; but the evidence, derived as it is exclusively from plant remains, is somewhat conflicting as to the precise epoch to which the lavas and beds of tuff containing the plant-remains are to be referred. the probabilities appear to be that they are of miocene age; and if so, the trachytic lavas, which in antrim are older than those containing plants, may be referred to a still earlier epoch--namely, that of the eocene.[ ] as plant remains are not very distinctive, the question regarding the exact time of the first volcanic eruptions will probably remain for ever undecided; but we are not likely to be much in error if we consider the entire volcanic period to range from the close of the eocene to that of the miocene; by far the greater mass of the volcanic rocks being referable to the latter epoch. in describing the british volcanic districts it will be most convenient to deal with them in three divisions--viz., those of antrim, mull, and skye, commencing with antrim.[ ] (_b._) _volcanic area._--the great sheets of basalt and other volcanic products of the north-east of ireland overspread almost the whole of the county antrim, and adjoining districts of londonderry and tyrone, breaking off in a fine mural escarpment along the northern shore of belfast lough and the sea coast throughout the whole of its range from larne harbour to lough foyle; the only direction in which these features subside into the general level of the country being around the shores of lough neagh. several outliers of the volcanic sheets are to be found at intervals around the great central plateau; such as those of rathlin island, island magee, and scrabo hill in co. down. the area of the basaltic plateau may be roughly estimated at , square miles. [illustration: fig. .--"the white rocks," portrush, co. antrim, showing the plateau-basalt resting on an eroded surface of the upper chalk, with bands of flint.--(from a photograph.)] the truncated edges of this marginal escarpment rising to levels of , to , feet, as in the case of benevenagh in co. derry, and , feet at mullaghmore, attest an originally greatly more extended range of the basaltic sheets; and it is not improbable that at the close of the miocene epoch they extended right across the present estuary of lough foyle to the flanks of the mountains of inishowen in donegal in one direction, and to those of slieve croob in the other. in the direction of scotland the promontories of kintyre and islay doubtless formed a part of the original margin. throughout this vast area the volcanic lavas rest on an exceedingly varied rocky floor, both as regards composition and geological age. (see fig. .) throughout the central, southern, eastern, and northern parts of their extent, the chalk formation may be considered to form this floor; but in the direction of armagh and tyrone, towards the southwestern margin, the basaltic sheets are found resting indiscriminately on silurian, carboniferous, and triassic strata. the general relations of the plateau-basalts to the underlying formations show, that at the close of the cretaceous period there had been considerable terrestrial disturbances and great subaërial denudation, resulting in some cases in the complete destruction of the whole of the cretaceous strata, before the lava floods were poured out; owing to which, these latter are found resting on formations of older date than the cretaceous.[ ] [illustration: fig. .--section across the volcanic plateau of antrim, from the highlands of inishowen, co. donegal, on the n.w., to belfast lough on the s.e., to show the relations of the volcanic rocks to the older formations.--b. basaltic sheets breaking off in high escarpments; t. trachyte porphyry of tardree mountain rising from below the newer plateau-basalts; c. upper chalk with flints; n.r. new red marl and sandstone (trias); m. metamorphic beds of quartzite, various schists and crystalline limestone; f. large fault.] [ ] mr. j. starkie gardner, from a recent comparison of the plant-remains of antrim and mull, concludes that "that they might belong to any age between the beginning and the end of the warmer eocene period; and that they cannot be of earlier, and are unlikely to be of later, date."--_trans. palæont. soc._, vol. xxxvii. ( ). [ ] having dealt with this district rather fully in _the physical geology and geography of ireland_ (edit. , p. ), and also in my presidential address (section c.) at the meeting of the british association, , a brief review of the subject will be sufficient here, the reader being referred to the former treatises for fuller details. the following should also be consulted: gen. portlock, _geology of londonderry and tyrone_ ( ); sir a. geikie, "history of volcanic action during the tertiary period in the british isles," _trans. roy. soc. edinburgh_, ; and the _descriptive memoirs_ of the geological survey relating to this tract of country. [ ] owing to the superposition of the basaltic masses on beds of chalk throughout a long line of coast, we are presented with the curious spectacle of the whitest rocks in nature overlain by the blackest, as may be seen in the cliffs at larne, glenarm, kinbane and portrush. (see fig. .) chapter ii. succession of volcanic eruptions. (_c._) _first stage._--the earliest eruptions of lava in the north-east of ireland belonged to the highly acid varieties, consisting of quartz-trachyte with tridymite.[ ] this rock rises to the surface at tardree and brown dod hills and templepatrick. it consists of a light-greyish felsitic paste enclosing grains of smoke-quartz, crystals of sanidine, plagioclase and biotite, with a little magnetite and apatite. it is a rock of peculiar interest from the fact that it is almost unique in the british islands, and has its petrological counterpart rather amongst the volcanic hills of the siebengebirge than elsewhere. it is generally consolidated with the columnar structure. [illustration: fig. .--part of the section shown in the quarry at templepatrick, showing the superposition of the basalt (_d_) to the trachyte (_b_), with the intervening bed of flint gravel (_c_). all these rocks are seen to rest upon an eroded surface of the chalk formation (_a_).] the trachyte appears to have been extruded from one or more vents in a viscous condition, the principal vent being probably situated under tardree mountain, where the rock occurs in greatest mass, and it probably arose as a dome-shaped mass, with a somewhat extended margin, above the floor of chalk which formed the surface of the ground.[ ] (fig. .) at templepatrick the columnar trachyte may be observed resting on the chalk, or upon a layer of flint gravel interposed between the two rocks, and which has been thrust out of position by a later intrusion of basalt coming in from the side.[ ] it is to be observed, however, that the trachytic lavas nowhere appear cropping out along with the sheets of basalt around the escarpments overlooking the sea, or inland; showing that they did not spread very far from their vents of eruption; a fact illustrating the lower viscosity, or fluidity, of the acid lavas as compared with those of the basic type. (_d._) _second stage._--after an interval, probably of long duration, a second eruption of volcanic matter took place over the entire area; but now the acid lavas of the first stage are replaced by basic lavas. now, for the first time, vast masses of basalt and dolerite are extruded both from vents of eruption and fissures; and, owing to their extreme viscosity, spread themselves far and wide until they reach the margin of some uprising ground of old palæozoic or metamorphic rocks by which the volcanic plain is almost surrounded. the great lava sheets thus produced are generally more or less amorphous, vesicular and amygdaloidal, often exhibiting the globular concentric structure, and weathering rapidly to a kind of ferruginous sand or clay under the influence of the atmosphere. successive extrusions of these lavas produce successive beds, which are piled one over the other in some places to a depth of feet; and at the close of the stage, when the volcanic forces had for the time exhausted themselves, the whole of the north-east of ireland must have presented an aspect not unlike that of one of those great tracts of similar lava in the region of idaho and the snake river in western america, described in a previous chapter. (_e._) _third stage (inter-volcanic)._--the third stage may be described as inter-volcanic. owing to the formation of a basin, probably not deep, and with gently sloping sides, a large lake was formed over the centre of the area above described. its floor was basalt, and the streams from the surrounding uplands carried down leaves and stems of trees, strewing them over its bed. occasionally eruptions of ash took place from small vents, forming the ash-beds with plants found at ballypallidy, glenarm, and along the coast as at carrick-a-raide. the streams also brought down sand and gravel from the uprising domes of trachyte, and deposited them over the lake-bed along with the erupted ashes.[ ] the epoch we are now referring to was one of economic importance; as, towards its close, there was an extensive deposition of pisolitic iron-ore over the floor of the lake, sometimes to the depth of two or three feet. this ore has been extensively worked in recent years. [illustration: fig. .--cliff section above the giant's causeway, coast of co. antrim, showing successive tiers of basaltic lava, with intervening bands of bole.] (_f._) _fourth stage (volcanic)._--the last stage described was brought to a termination by a second outburst of basic lavas on a scale probably even grander than the preceding. these lavas consisting of basalt and dolerite, with their varieties, and extruded from vents and fissures, spread themselves in all directions over the pre-existing lake deposits or the older sheets of augitic lava, and probably entirely buried the trachytic hills. these later sheets solidified into more solid masses than those of the second stage. they form successive terraces with columnar structure, each terrace differing from that above and below it in the size and length of the columns, and separated by thin bands of "bole" (decomposed lava), often reddish in colour, clearly defining the limits of the successive lava-flows. nowhere throughout the entire volcanic area are these successive terraces so finely laid open to view as along the north coast of antrim, where the lofty mural cliffs, worn back into successive bays with intervening headlands by the irresistible force of the atlantic waves, present to the spectator a vertical section from to feet in height, in which the successive tiers of columnar basalt, separated by thin bands of bole, are seen to rise one above the other from the water's edge to the summit of the cliff, as shown in fig. . here, also, at the western extremity of the line of cliffs we find that remarkable group of vertical basaltic columns, stretching from the base of the cliff into the atlantic, and known far and wide by the name of "the giant's causeway," the upper ends of the columns forming a tolerably level surface, gently sloping seawards, and having very much the aspect of an artificial tesselated pavement on a huge scale. a portion of the causeway, with the cliff in the background, is shown in the figure (fig. ). the columns are remarkable for their symmetry, being generally hexagonal, though occasionally they are pentagons, and each column is horizontally traversed by joints of the ball-and-socket form, thus dividing them into distinct courses of natural masonry. these are very well shown in the accompanying view of the remarkable basaltic pillars known as "the chimneys," which stand up from the margin of the headland adjoining the causeway, monuments of past denudation, as they originally formed individuals amongst the group belonging to one of the terraces in the adjoining coast.[ ] (fig. ). [illustration: fig. .--the giant's causeway, formed of basaltic columns in a vertical position, and of pentagonal or hexagonal section; above the causeway is seen a portion of the cliff composed of tiers of lava with intervening bands of bole, etc.--(from a photograph.)] [illustration: fig. .--"the chimneys," columns of basalt on slope of cliff overlooking the atlantic, north coast of co. antrim. the horizontal segments, or cup-and-ball joints, of the columns are well shown in this figure. (from a photograph.)] (_g._) _original thickness of the antrim lavas._--it is impossible to determine with certainty what may have been the original thickness of the accumulated sheets of basic lavas with their associated beds of ash and bole. the greatest known thickness of the lower zone of lavas is, as i have already stated, about feet. the intermediate beds of ash and bole sometimes attain a thickness of feet, and the upper group of basalt about feet; these together would constitute a series of over , feet in thickness. but this amount, great as it is, is undoubtedly below the original maximum, as the uppermost sheets have been removed by denuding agencies, we know not to what extent. nor is it of any great importance. sufficient remains to enable us to form a just conception of the magnitude both as regards thickness and extent of the erupted matter of the miocene period over the north-east of ireland and adjoining submerged tracts, and of the magnitude of the volcanic operations necessary for the production of such masses. (_h._) _volcanic necks._--as already remarked, no craters of eruption survive throughout the volcanic region of the north-east of ireland, owing to the enormous extent of the denudation which this region has undergone since the miocene epoch; but the old "necks" of such craters--in other words, the pipes filled with either solid basalt, or basalt and ashes--are still to be found at intervals over the whole area. owing to the greater solidity of the lava which filled up these "necks" over the plateau-basaltic sheets which surround them, they appear as bosses or hills rising above the general level of the ground. one of these bosses of highly columnar basalt occurs between portrush and bushmills, not far from dunluce castle, another at scawt hill, near glenarm, and a third at carmoney hill above belfast lough. but by far the most prominent of these old solidified vents of eruption is that of sleamish, a conspicuous mountain which rises above the general level of the plateau near ballymena, and attains an elevation of , feet above the sea. seen from the west, the mountain has the appearance of a round-topped cone; but on examination it is found to be in reality a huge dyke, breaking off abruptly towards the north-west, in which direction it reaches its greatest height, then sloping downwards towards the east. this form suggests that sleamish is in reality one of the fissure-vents of eruption rather than the neck of an old volcano. the rock of which it is formed consists of exceedingly massive, coarsely-crystalline dolerite, rich in olivine, and divided into large quadrangular blocks by parallel joint planes. its junction with the plateau-basalt from which it rises can nowhere be seen; but at the nearest point where the two rocks are traceable the plateau-basalt appears to be somewhat indurated; breaking with a splintery fracture and a sharp ring under the hammer, suggesting that the lava of sleamish had been extruded through the horizontal sheets, and had considerably indurated the portions in contact with, or in proximity to, it.[ ] amongst the vents filled with ash and agglomerate, the most remarkable is that of carrick-a-raide, near ballycastle. it forms this rocky island and a portion of the adjoining coast, where the beds of ash are finely displayed; consisting of fragments and bombs of basalt, with pieces of chalk, flint, and peperino, which is irregularly bedded. these ash-beds attain a thickness of about feet just below the road to ballycastle, but rapidly tail out in both directions from the locality of the vent. just below the ash-beds, the white chalk with flints may be seen extending down into the sea-bed. nowhere in antrim is there such a display of volcanic ash and agglomerate as at this spot.[ ] (_i._) _dykes: conditions under which they were erupted._--no one can visit the geological sections in co. antrim and the adjoining districts of down, armagh, derry, and tyrone, without being struck by the great number and variety of the igneous dykes by which the rocks are traversed. the great majority of these dykes are basaltic, and they are found traversing all the formations, including the cretaceous and tertiary basaltic sheets. the carlingford and mourne mountains are seamed with such dykes, and they are splendidly laid open to view along the coast south of newcastle in co. down, as also along the antrim coast from belfast to larne. the fine old castle of carrickfergus has its foundations on one of those dyke-like intrusions, but one of greater size than ordinary. all the dykes here referred to are not, however, of the same age, as is conclusively proved by sections amongst the mourne mountains where cliffs of lower silurian strata, superimposed on the intrusive granite of the district, exhibit two sets of basaltic dykes--one (the older) abruptly terminated at the granite margin, the other and newer penetrating the granite and silurian rocks alike. it is not improbable that the older dykes belong to the carboniferous or permian age, while the newer are with equal probability of tertiary age. sir a. geikie has shown that the tertiary dykes of the north of ireland are representatives of others occurring at intervals over the north of england, and central and western scotland, all pointing towards the central region of volcanic activity; or in a parallel direction thereto, approximating to the n.w. in ireland, the island of islay, and east argyleshire, but in the centre of scotland generally ranging from east to west.[ ] the area affected by the dykes of undoubted tertiary age geikie estimates at no less than , square miles--a territory greater than either scotland or ireland, and equal to more than a third of the total land-surface of the british isles;[ ] and he regards them as posterior "to the rest of the geological structures of the regions which they traverse." it is clear that the dykes referred to belong to one great system of eruption or intrusion; and they may be regarded as the manifestation of the final effort of internal forces over this region of the british isles. they testify to the existence of a continuous _magma_ (or shell) of augitic lava beneath the crust; and as the aggregate horizontal extent of all these dykes, or of the fissures which they fill, must be very considerable, it is clear that the crust through which they have been extruded has received an accession of horizontal space, and has been fissured by forces acting from beneath, as the late mr. hopkins, of cambridge, had explained on mechanical grounds in his elaborate essay many years ago.[ ] this view occurred to myself when examining the region of the north-east of ireland, but i was not then aware that it had been dealt with on mathematical principles by so eminent a mathematician. the bulging of the crust is a necessary consequence of the absence of plication of the strata due to the extrusion of this enormous quantity of molten lava; and the intrusion of thousands of dykes over the north-east of ireland, unaccompanied by foldings of the strata, must have added a horizontal space of several thousand feet to that region.[ ] [ ] a peculiar form of crystalline quartz first recognized in this rock by a distinguished german petrologist, the late prof. a. von lasaulx, who visited the district in . [ ] sir a. geikie has disputed the correctness of the view, which i advocated as far back as , that the trachytic lavas of antrim are the earliest products of volcanic action; but at the time he wrote his paper on the volcanic history of these islands, it was not known that pebbles of this trachyte are largely distributed amongst the ash-beds which occur in the very midst of the overlying basaltic sheets, as i shall have to explain later on. this discovery puts the question at rest as regards the relations of the two sets of rocks. [ ] this remarkable section at the chalk quarries of templepatrick the author has figured and described in the _physical geology and geography of ireland_, p. , nd edit. ( ), where the reader will find the subject discussed more fully than can be done here. [ ] these pebbles were first noticed by mr. mchenry, of the irish geological survey, in . [ ] the vertical position of the columns of the giant's causeway is rather enigmatical. the causeway cannot be a dyke, as has often been supposed, otherwise the columns would have been horizontal, _i.e._, at right angles to the sides of the dyke. mr. r. g. symes, of the geological survey, has suggested that the causeway columns have been vertically lowered between two lines of fault, and that originally they formed a portion of the tier of beautiful columns seen in the cliff above, and known as "the organ." [ ] sleamish and several other of the antrim vents are described by sir a. geikie in the monograph already referred to, _loc. cit._, p. , _et seq._ also in the _expl. memoirs of the geological survey of ireland_. [ ] a diagrammatised section of the carrick-a-raide volcanic neck is given by sir a. geikie, _loc. cit._, p. . [ ] geikie, _loc. cit._, p. , _et seq._ [ ] p. . the view that the crust of the earth has been horizontally extended by the intrusion of dykes is noticed by mcculloch in reference to the dykes of skye. [ ] hopkins, _cambridge phil. trans._, vol. vi. p. ( ). [ ] as suggested in my presidential address to section c. of the british association at belfast, . chapter iii. island of mull and adjoining coast. the island of mull, with the adjoining districts of morvern and ardnamurchan, forms the more southern of the two chief centres of tertiary volcanic eruptions in the west of scotland, that of skye being the more northern. these districts have been the subject of critical and detailed study by several geologists, from mcculloch down to the present day; and amongst the more recent, sir archibald geikie and professor judd hold the chief place. unfortunately, the interpretation of the volcanic phenomena by these two accomplished observers has led them to very different conclusions as regards several important points in the volcanic history of these groups of islands; as, for example, regarding the relative ages of the plateau-basalts and the acid rocks, such as the trachytes and granophyres; again as regards the presence of distinct centres of eruption; and also as regards the relations of the gabbros of skye to the basaltic sheets. such being the case, it would appear the height of rashness on the part of the writer, especially in the absence of a detailed examination of the sections over the whole region, to venture on a statement of opinion regarding the points at issue; and he must, therefore, content himself with a brief account of the phenomena as gathered from a perusal of the writings of these and other observers,[ ] guided also to some extent by the analogous phenomena presented by the volcanic region of the north-east of ireland. (_a._) _general features._--as in the case of the antrim district, the island of mull and adjoining tracts present us with the spectacle of a vast accumulation of basaltic lava-flows, piled layer upon layer, with intervening beds of bole and tuff, up to a thickness, according to geikie, of about , feet. at the grand headland of gribon, on the west coast, the basaltic sheets are seen to rise in one sheer sweep to a height of , feet, and then to stretch away with a slight easterly dip under ben more at a distance of some eight miles. this mountain, the upper part of which is formed of beds of ashes, reaches an elevation of , feet, so that the accumulated thickness of the beds of basalt under the higher part of the mountain must be at least equal to the amount stated above--that is, twice as great as the representative masses of antrim. the base of the volcanic series is seen at carsaig and gribon to rest on cretaceous and jurassic rocks, like those of antrim; hence the tertiary age is fully established by the evidence of superposition. this was further confirmed by the discovery by the duke of argyll,[ ] some years ago ( ), of bands of flint-gravel and tuff, with dicotyledonous leaves amongst the basalts of ardtun head. the basement beds of tuff and gravel contain, besides pebbles of flint and chalk, others of sanidine trachyte, showing that highly acid lavas had been extruded and consolidated before the first eruption of the plateau-basalts; another point of analogy between the volcanic phenomenon of antrim and the inner hebrides. these great sheets of augitic lava extend over the whole of the northern tract of mull, the isles of ulva and staffa, and for a distance of several miles inwards from the northern shore of the sound of mull, covering the wild moorlands of morvern and ardnamurchan, where they terminate in escarpments and outlying masses, indicating an originally much more extended range than at the present day. the summits of ben more and its neighbouring height, ben buy, are formed of beds of ash and tuff. the volcanic plateau is, according to judd, abruptly terminated along the southern side by a large vault, bringing the basalt in contact with palæozoic rocks.[ ] (_b._) _granophyres._--the greater part of the tract lying to the south of loch na keal, which almost divides mull into two islands, and extending southwards and eastwards to the shores of the firth of lorn and the sound of mull, is formed of a peculiar group of acid (or highly silicated) rocks, classed under the general term of "granophyres." these rocks approach towards true granites in one direction, and through quartz-porphyry and felsite to rhyolite in another--probably depending upon the conditions of cooling and consolidation. in their mode of weathering and general appearance on a large scale, they present a marked contrast to the basic lavas with which they are in contact from the coast of l. na keal to that of l. buy. the nature of this contact, whether indicating the priority of the granophyres to the plateau-basalts or otherwise, is a matter of dispute between the two observers above named; but the circumstantial account given by sir a. geikie,[ ] accompanied by drawings of special sections showing this contact, appears to prove that the granophyre is the newer of the two masses of volcanic rock, and that it has been intruded amongst the basaltic-lavas at a late period in the volcanic history of these islands. a copy of one of these sketches is here given (fig. ), according to which the felsite is shown to penetrate the basaltic sheets at alt na searmoin in mull; other sections seen at cruach torr an lochain, and on the south side of beinn fada, appear to lead to similar conclusions. these rocks are penetrated by numerous basaltic dykes. [illustration: fig. .--section at alt na searmoin, mull, to show the intrusion of felsite (or granophyre) (_b_) into basalt and dolerite (_a_) of the plateau-basalt series.--(geikie.)] (_c._) _representative rocks of mourne and carlingford, ireland._--assuming sir a. geikie's view to be correct, it is possible that we may have in the granite and quartz-porphyries of mourne and carlingford representatives of the granites, granophyres, and other acid rocks of the later period of mull. the granite of mourne is peculiar in structure, and differs from the ordinary type of that rock in which the silica forms the ground mass. in the case of the granite of the mourne mountains, the rock consists of a crystalline granular aggregate of orthoclase, albite, smoke-quartz, and mica; it is also full of drusy cavities, in which the various minerals crystallise out in very perfect form. as far as regards direct evidence, the age of this rock can only be stated to be post-carboniferous, and earlier than certain tertiary basaltic dykes by which it is traversed. the granophyres of mull are traversed by similar dykes, which are representatives of the very latest stage of volcanic action in the british islands. the author is therefore inclined to concur with sir a. geikie in assigning to the granite of the mourne mountains, and the representative felsitic rocks of the carlingford mountains, a tertiary age--in which case the analogy between the volcanic phenomena of the inner hebrides and of the north-east of ireland would seem to be complete.[ ] [ ] geikie, _proc. roy. soc. edinburgh_ ( ); _brit. assoc. rep._ (dundee, ); "tertiary volcanic rocks of the british isles," _quart. journ. geol. soc._, vol. xxvii. p. ; also, "history of volcanic action in british isles," _trans. roy. soc. edin._ ( ); judd, "on the ancient volcanoes of the highlands," etc., _quart. journ. geol. soc._, vol. xxx. p. ; and _volcanoes_, p. . [ ] _brit. assoc. rep._ for , p. . [ ] judd, _quart. jour. geol. soc._, vol. xxx. p. . [ ] _history of volcanic action, etc._, _loc. cit._ p. , _et seq._ the "granophyres" of geikie come under the head of "felsites," passing into "granite" in one direction and quartz-trachyte in another, according to judd; the proportion of silica from to per cent.--_quart. jour. geol. soc._, vol. xxx. p. . [ ] this view the author has expressed in a recent edition of _the physical geology of ireland_, p. ( ). chapter iv. isle of skye. this is the largest and most important of all the tertiary volcanic districts, but owing to the extensive denudation to which, in common with other tertiary volcanic regions of the british isles, it has been subjected, its present limits are very restricted comparatively to its original extent. not only is this evident from the manner in which the basaltic sheets terminate along the sea-coast in grand mural cliffs, as opposite "macleod's maidens," and at the entrance to lough bracadale on the western coast, but the evidence is, according to sir a. geikie, still more striking along the eastern coast; showing that the jurassic, and other older rocks there visible, were originally buried deep under the basaltic sheets which have been stripped from off that part of the country. these great plateau-basalts occupy about three-fourths of the entire island along the western and northern areas, rising into terraced mountains over , feet in height, and are deeply furrowed by glens and arms of the sea, along which the general structure of the tableland is laid open, sometimes for leagues at a time. it is towards the south-eastern part of the island that the most interesting and important phenomena are centred; for here we meet with representatives of the acid (or highly silicated) group of rocks, and of remarkable beds of gabbro, which have long attracted the attention of petrologists. these latter beds, throughout a considerable distance round the flanks of the cuillin hills, are interposed between the acid rocks and the plateau-basalts; but towards the north, on approaching lough sligahan, the acid rocks, consisting of granophyres, quartz-porphyries, and hornblendic-granitites, are in direct contact with the plateau-basalts; and, according to the very circumstantial account of sir a. geikie, are intrusive into them; not only sending veins into the basaltic sheets, but also producing a marked alteration in their structure where they approach the newer intrusive mass. equally circumstantial is the same author's account of the relations of the granophyres to the gabbros,[ ] as seen at meall dearg and the western border of the cuillin hills--where the former rock may be seen to send numerous veins into the latter. not only is this so, but the granophyre is frequently seen to truncate, and abruptly terminate some of the basaltic dykes by which the basic sheets are traversed--as in the neighbourhood of beinn na dubhaic. all these phenomena strongly remind us of the conditions of similar rocks amongst the mountains of mourne and carlingford in ireland; where, at barnaveve, the syenite (or hornblendic quartz-felsite) is seen to break through the masses of olivine gabbro, and send numerous veins into this latter rock.[ ] the interpretation here briefly sketched differs widely from that arrived at by professor judd. the granitoid masses of the red mountains (beinn dearg) and the neighbouring heights are, in his view, the roots of the great volcano from which were erupted the various lavas; the earlier eruptions producing the acid lavas, to be followed by the gabbros, and these by the plateau-basaltic sheets, which stretch away towards the north and west into several peninsulas. thus he holds that "the rocks of basic composition were ejected subsequently to those of the acid variety," and appeals to various sections in confirmation of this view.[ ] to reconcile these views is at present impossible; but as the controversy between these two observers is probably not yet closed, there is room for hope that the true interpretation of the relations of these rocks to each other will ere long be fully established. [ ] geikie, _loc. cit._, p. , etc. [ ] _physical geology of ireland_, nd edition, p. (fig. ). professor judd has also come to the conclusion that the granite of mourne is of tertiary age, _quart. jour. geol. soc._, vol. xxx. p. . [ ] judd, _loc. cit._, p. . chapter v. the scuir of eigg. amongst the more remarkable of the smaller islets are those of eigg, rum, canna, and muck, lying between mull on the south and skye on the north, and undoubtedly at one time physically connected together. the island of eigg is especially remarkable for the fact, as stated by geikie, that here we have the one solitary case of "a true superficial stream of acid lava--that of the scuir of eigg."[ ] (fig. .) this forms a sinuous ridge, composed of pitchstone of several kinds, of over two miles in length, rising from the midst of a tableland of bedded basalt and tuff to a height of , feet above the ocean; the plateau-basalt is traversed by basaltic dykes, ranging in a n.w.-s.e. direction. but what is specially remarkable is the evidence afforded by an examination of the course of the scuir, that it follows the channel of an ancient river-valley, which has been hollowed out in the surface of the plateau. the course of this channel is indicated by the presence of a deposit of river-gravel, which in some places forms a sort of cushion between the base of the scuir and the side of the channel. over this gravel-bed the viscous pitchstone-lava appears to have flowed, taking possession of the river-channel, and also of the beds of several small tributary streams which flowed into the channel of the scuir. the recent date of the pitchstone forming this remarkable mural ridge, once occupying the bed of a river-channel, is shown by the fact that the basaltic dykes which traverse the plateau-basalts are truncated by the river-gravel, which is, therefore, more recent; and, as we have seen, the pitchstone stream is more recent than the river-gravel. but at the time when this last volcanic eruption took place, the physical geography of the whole region must have been very different from that of the present time. from the character and composition of the pebbles in the old river-bed, amongst which are cambrian sandstone, quartzite, clay-slate, and white jurassic limestone, sir a. geikie concludes that when the river was flowing, the island must have been connected with the mainland to the east where the parent masses of these pebbles are found. [illustration: fig. .--view of the scuir of eigg from the east. the lower portion of the mountain is formed of bedded basalt, or dolerite with numerous dykes and veins of basalt, felstone, and pitchstone; the upper cliff, or scuir, is composed of pitchstone of newer age, the remnant of a lava flow which once filled a river channel in the basaltic sheets. a dyke, or sheet, of porphyry is seen to be interposed between the scuir and the basaltic sheets.--(after geikie.)] _effects of denudation._--the position of the scuir of eigg and its relations to the basaltic sheets show the enormous amount of denudation which these latter have undergone since the stream of pitchstone-lava filled the old river channel. the walls, or banks, of the channel have been denuded away, thus converting the pitchstone casting into a projecting wall of rock. that it originally extended outwards into the ocean to a far greater distance than at present is evident from the abruptly truncated face of the cliff; and yet this remarkable volcanic mass seems to have been, perhaps, the most recent exhibition of volcanic action to be found in the british isles. it is perhaps, on this account, the most striking of the numerous examples exhibited throughout the west of scotland and the north-east of ireland of the enormous amount of denudation to which these districts have been subjected since the extinction of the volcanic fires; and this at a period to which we cannot assign a date more ancient than that of the pliocene. yet, let us consider for a moment to what physical vicissitudes these districts have been subjected since that epoch. assuming, as we may with confidence, that the volcanic eruptions were subaërial, and that the tracts covered by the plateau-basalts were in the condition of dry land when the eruptions commenced, in this condition they continued in the main throughout the period of volcanic activity. but the eruptions had scarcely ceased, and the lava floods and dykes become consolidated, before the succeeding glacial epoch set in; when the snows and glaciers of the scottish highlands gradually descending from their original mountain heights, and spreading outwards in all directions, ultimately enveloped the whole of the region we are now considering until it was entirely concealed beneath a mantle of ice moving slowly, but irresistibly, outwards towards the atlantic, crossing the deep channels, such as the sound of mull and the minch, climbing up the sides of opposing rocks and islands until even the outer hebrides and the north-east of ireland were covered by one vast mantle of ice and snow. the movement of such a body of ice over the land must have been attended with a large amount of abrasion of the rocky floor; nor have the evidences of that abrasion entirely disappeared even at the present day. we still detect the grooves and scorings on the rock-surfaces where they have been protected by a coating of boulder clay; and we still find the surface strewn with the blocks and _débris_ of that mighty ice-flood. but whatever may have been the amount of erosion caused by the great ice-sheet, it was chiefly confined to the more or less horizontal surface-planes. erosion of another kind was to succeed, and to produce more lasting effects on the configuration of the surface. on the disappearance of the ice-sheet, an epoch characterised by milder conditions of climate set in. this was accompanied by subsidence and submersion of large tracts of the land during the interglacial stage; so that the sea rose to heights of several hundred feet above the present level, and has left behind stratified gravels with shells at these elevations in protected places. during this period of depression and of subsequent re-emergence the wave-action of the atlantic waters must have told severely on the coast and islands, wearing them into cliffs and escarpments, furrowing out channels and levelling obstructions. such action has gone on down to the present day. the north-west of scotland and of ireland has been subjected throughout a very lengthened period to the wear and tear of the atlantic billows. in the case of the former, the remarkable breakwater which nature has thrown athwart the north-west highlands in the direction of the waves, forming the chain of islands constituting the outer hebrides, and composed of very tough archæan gneiss and schist, has done much to retard the inroads which the waves might otherwise have made on the isle of skye; while coll and tiree, composed of similar materials, have acted with similar beneficent effect for mull and the adjoining coasts. but such is the tremendous power of the atlantic billows when impelled by westerly winds, that to their agency must be mainly attributed the small size of the volcanic land-surfaces as compared with their original extent, and the formation of those grand headlands which are presented by the igneous masses of skye, ardnamurchan, and mull towards the west. rain and river action, supplemented by that of glaciers, have also had a share in eroding channels and wearing down the upper surface of the ground, with the result we at present behold in the wild and broken scenery of the inner hebrides and adjoining coast. [ ] geikie, _loc. cit._, p. ; also _quart. jour. geol. soc._, vol. xxvii. p. . chapter vi. isle of staffa. reference has been made to this remarkable island in a former page, but some more extended notice is desirable before leaving the region of the inner hebrides. along with the islands of pladda, treshnish, and blackmore, staffa is one of the outlying volcanic islands of the group, being distant about six miles from the coast of mull, and indicates the minimum distance to which the plateau-basaltic sheets originally extended in the direction of the old marginal lands of tiree and coll. the island consists of successive sheets of bedded basaltic lava, with partings of tuff, one of which of considerable thickness is shown to lie at the base of the cliff on the south-west side of the island.[ ] the successive lava-sheets present great varieties of structure, like those on the north coast of antrim; some being amorphous, others columnar, with either straight or bent columns. the lava-sheet out of which fingal's cave is excavated consists of vertical prisms, beautifully formed, and surmounted by an amorphous mass of the same material. at the entrance of the boat cave we have a somewhat similar arrangement of the columns;[ ] but at the clam-shell cave the prisms are curved, indicating some movement in the viscous mass before they had been fully consolidated. fingal's cave is called after the celebrated prince of morvern (or morven), a province of ancient caledonia. he is supposed to have been the father of ossian, the celtic bard rendered famous by macpherson. the cave, one of many which pierce the coast-cliffs of western scotland, is feet in length, feet in height, and feet in width. on all sides regular columns of basalt, some entire, others broken, rise out of the water and support the roof. the cave is only accessible in calm weather. [ ] a drawing of this cliff is given by geikie in the _manual of geology_ (jukes and geikie), rd edition, p. . [ ] prestwich, _geology_, vol. i. p. , where a view of this cave is given. part v. pre-tertiary volcanic rocks. chapter i. the deccan trap-series of india. the great outpourings of augitic lava of tertiary and recent times which we have been considering appear to have been anticipated in several parts of the world, more especially in peninsular india and in africa, and it is desirable that we should devote a few pages to the description of these remarkable volcanic formations, as they resemble, both in their mode of occurrence and general structure, some of the great lava-floods of a more recent period we have been considering. of the districts to be described, the first which claims our notice is the deccan. (_a._) _extent of the volcanic plateau._--the volcanic plateau of the deccan stretches from the borders of the western ghats and the sea-coast near bombay inland to amarantak, at the head of the narbudda river (long. ° e.), and from belgaum (lat. ° ' n.) to near goona (lat. ° '). the vast area thus circumscribed is far from representing the original extent of the tract overspread by the lava-floods, as outlying fragments of these lavas are found as far east as long. ° e. in one direction, and at kattiwar and cutch in another. the present area, however, is estimated to be not less than , square miles.[ ] (_b._) _nature and thickness of the lava-flows._--this tract is overspread almost continuously by sheets of basaltic lava, with occasional bands of fresh-water strata containing numerous shells, figured and described by hislop, and believed by him to be of lower eocene age. the lava-sheets vary considerably in character, ranging from finest compact basalt to coarsely crystalline dolerite, in which olivine is abundant. the columnar structure is not prevalent, the rock being either amorphous, or weathering into concentric shells. volcanic ash, or bole, is frequently found separating the different lava-flows; and in the upper amygdaloidal sheets numerous secondary minerals are found, such as quartz, agate and jasper, stilbite and chlorite. the total thickness of the whole series, where complete, is about , feet, divided as follows: . upper trap; with ash and inter-trappean beds , feet . middle trap; sheets of basalt and ash , " . lower trap; basalt with inter-trappean beds " -------- , " ======== throughout the region here described these great sheets of volcanic rock are everywhere approximately horizontal, and constitute a table-land of , to , feet in elevation, breaking off in terraced escarpments, and penetrated by deep river-valleys, of which the narbudda is the most important. the foundation rock is sometimes metamorphic schist, or gneiss, at other times sandstone referred by hislop to jurassic age; and in no single instance has a volcanic crater or focus of eruption been observed. but outside the central trappean area volcanic foci are numerous, as in cutch, the rajhipla hills and the lower narbudda valley. the original excessive fluidity of the deccan trap is proved by the remarkable horizontality of the beds over large areas, and the extensive regions covered by very thin sheets of basalt or dolerite. (_c._) _geological age._--as regards the geological age of this great volcanic series much uncertainty exists, owing to the absence of marine forms in the inter-trappean beds. one single species, _cardita variabilis_, has been observed as occurring in these beds, and in the limestone below the base of the trap at dudukur. the _facies_ of the forms in this limestone is tertiary; but there is a remarkable absence of characteristic genera. on the other hand, mr. blanford states that the bedded traps are seen to underlie the eocene tertiary strata with _nummulites_ in guzerat and cutch,[ ] which would appear to determine the limit of their age in one direction. on balancing the evidence, however, it is tolerably clear that the volcanic eruptions commenced towards the close of the cretaceous period, and continued into the commencement of the tertiary, thus bridging over the interval between the two epochs; and since the greater sheets have been exposed throughout the whole of the tertiary and quarternary periods, it is not surprising if they have suffered enormously from denuding agencies, and that any craters or cones of eruption that may once have existed have disappeared. [ ] the deccan traps have been described by sykes, _geol. trans._, nd series, vol. iv.; also rev. s. hislop, "on the geology of the neighbourhood of nagpur, central india," _quart. journ. geol. soc._, vol. x. p. ; and _ibid._, vol. xvi. p. . also, h. b. medlicott and w. t. blanford, _manual of the geology of india_, vol. i. ( ). [ ] blanford, _geology of abyssinia_, p. . chapter ii. abyssinian table-lands. another region in which the volcanic phenomena bear a remarkable analogy to those of central india, just described, is that of abyssinia. nor are these tracts so widely separated that they may not be considered as portions of one great volcanic area extending from abyssinia, through southern arabia, into cutch and the deccan, in the one direction, while the great volcanic cones of kenia and kilimanjaro, with their surrounding tracts of volcanic matter, may be the extreme prolongations in the other. along this tract volcanic operations are still active in the gulf of aden; and cones quite unchanged in form, and evidently of very recent date, abound in many places along the coast both of arabia and africa. the volcanic formations of this tract are, however, much more recent than those which occupy the high plateaux of central and southern abyssinia of which we are about to speak. (_a._) _physical features._--abyssinia forms a compact region of lofty plateaux intersected by deep valleys, interposed between the basin of the nile on the west, and the low-lying tract bordering the red sea and the indian ocean on the east. the plateaux are deeply intersected by valleys and ravines, giving birth to streams which feed the head waters of the blue nile (bahr el arak) and the atbara. several fine lakes lie in the lap of the mountains, of which the zana, or dembia, is the largest, and next ashangi, visited by the british army on its march to magdala in , and which, from its form and the volcanic nature of the surrounding hills, appears to occupy the hollow of an extinct crater. the table-land of abyssinia reaches its highest elevation along the eastern and southern margin, where its average height may be , to , feet; but some peaks rise to a height of , to , feet in shoa and ankobar.[ ] (_b._) _basaltic lava sheets._--an enormous area of this country seems to be composed of volcanic rocks chiefly in the form of sheets of basaltic lava, which rise into high plateaux, and break off in steep--sometimes precipitous--mural escarpments along the sides of the valleys. these are divisible into the following series:-- ( ) _the ashangi volcanic series._--the earliest forerunners of the more recent lavas seem to have been erupted in jurassic times, in the form of sheets of contemporaneous basalt or dolerite amongst the antola limestones which are of this period. but the great mass of the volcanic rocks are much more recent, and may be confidently referred to the late cretaceous or early tertiary epochs. their resemblance to the great trappean series of western india, even in minute particulars, is referred to by mr. blanford, who suggests the view that they belong to one and the same great series of lava-flows extruded over the surface of this part of the globe. this view is inherently probable. they consist of basalts and dolerites, generally amygdaloidal, with nodules of agate and zeolite, and are frequently coated with green-earth (chlorite). beds of volcanic ash or breccia also frequently occur, and often contain augite crystals. at senafé, hills of trachyte passing into claystone and basalt were observed by mr. blanford, but it is not clear what are their relations to the plateau-basaltic sheets.[ ] ( ) _magdala volcanic series._--this is a more recent group of volcanic lavas, chiefly distinguished from the lower, or ashangi, group, by the occurrence of thick beds of trachyte, usually more or less crystalline, and containing beautiful crystals of sanidine. the beds of trachyte break off in precipitous scarps, and being of great thickness and perfectly horizontal, are unusually conspicuous. mr. blanford says, with regard to this group, that there is a remarkable resemblance in its physical aspect to the scenery of the deccan and the higher valleys of the western ghats of india, but the peculiarities of the landscape are exaggerated in abyssinia. many of the trachytic beds are brecciated and highly columnar; sedimentary beds are also interstratified with those of volcanic origin. the magdala group is unconformable to that of ashangi in some places. a still more recent group of volcanic rocks appears to occur in the neighbourhood of senafé, consisting of amorphous masses of trachyte, often so fine-grained and compact as to pass into claystone and to resemble sandstone. at akub teriki the rocks appear to be in the immediate vicinity of an ancient vent of eruption. from what has been said, it will be apparent that abyssinia offers volcanic phenomena of great interest for the observer. there is considerable variety in the rock masses, in their mode of distribution, and in the scenery which they produce. the extensive horizontal sheets of lava are suggestive of fissure-eruption rather than of eruption through volcanic craters; and although these may have once been in existence, denudation has left no vestiges of them at the present day. in all these respects the resemblance of the volcanic phenomena to those of peninsular india is remarkably striking; it suggests the view that they are contemporaneous as regards the time of their eruption, and similar as regards their mode of formation. [ ] w. t. blanford, _geology of abyssinia_, pp. - . [ ] blanford, _loc. cit._, p. . chapter iii. cape colony. _basalt of the plateau._--the extensive sheets of plateau-basalt forming portions of the neuweld range and the elevated table-land of cape colony, may be regarded as forerunners of those just described, and possibly contemporaneous with the ashangi volcanic series of abyssinia. the great basaltic sheets of the cape colony are found capping the highest elevations of the camderboo and stormberg ranges, as well as overspreading immense areas of less elevated land, to an extent, according to professor a. h. green, of at least , square miles.[ ] amongst these sheets, innumerable dykes, and masses of solid lava which filled the old vents of eruption, are to be observed. the floor upon which the lava-floods have been poured out generally consists of the "cave sandstone," the uppermost of a series of deposits which had previously been laid down over the bed of an extensive lake which occupied this part of africa during the mesozoic period. after the deposition of this sandstone, the volcanic forces appear to have burst through the crust, and from vents and fissures great floods of augitic lava, with beds of tuff, invaded the region occupied by the waters of the lake. the lava-sheets have since undergone extensive denudation, and are intersected by valleys and depressions eroded down through them into the sandstone floor beneath; and though the precise geological period at which they were extruded must remain in doubt, it appears probable that they may be referred to that of the trias.[ ] [ ] green. "on the geology of the cape colony," _quart. jour. geol. soc._, vol. xliv. ( ). [ ] the district lying along the south coast of africa is described by andrew g. bain, in the _trans. geol. soc._, vol. vii. ( ); but there is little information regarding the volcanic region here referred to. chapter iv. volcanic rocks of past geological periods of the british isles. it is beyond the scope of this work to describe the volcanic rocks of pre-tertiary times over various parts of the globe. the subject is far too large to be treated otherwise than in a distinct and separate essay. i will therefore content myself with a brief enumeration of the formations of the british isles in which contemporaneous volcanic action has been recognised.[ ] there is little evidence of volcanic action throughout the long lapse of time extending backwards from the cretaceous to the triassic epochs, that is to say, throughout the mesozoic or secondary period, and it is not till we reach the palæozoic strata that evidence of volcanic action unmistakably presents itself. _permian period._--in ayrshire, and in the western parts of devonshire, beds of felspathic porphyry, felstone and ash are interstratified with strata believed to be of permian age. in devonshire these have only recently been recognised by dr. irving and the author as of permian age, the strata consisting of beds of breccia, lying at the base of the new red sandstone. those of ayrshire have long been recognised as of the same period; as they rest unconformably on the coal measures, and consist of porphyrites, melaphyres, and tuffs of volcanic origin. _carboniferous period._--volcanic rocks occur amongst the coal-measures of england and scotland, while they are also found interbedded with the carboniferous limestone series in derbyshire, scotland, and co. limerick in ireland. the rocks consist chiefly of basalt, dolerite, melaphyre and felstone. _devonian period._--volcanic rocks of devonian age occur in the south of scotland, consisting of felstone-porphyries and melaphyres; also at boyle, in roscommon, and amongst the glengariff beds near killarney in ireland. _upper silurian period._--volcanic rocks of this stage are only known in ireland, on the borders of cos. mayo and galway, west of lough mask, and at the extreme headland of the dingle promontory in co. kerry. they consist of porphyrites, felstones and tuffs, or breccias, contemporaneously erupted during the wenlock and ludlow stages. around the flanks of muilrea, beds of purple quartz-felstone with tuff are interstratified with the upper silurian grits and slates. _lower silurian period._--volcanic action was developed on a grand scale during the arenig and caradoc-bala stages, both in wales and the lake district, and in the llandeilo stage in the south of scotland. the felspathic lavas, with their associated beds of tuff and breccia, rise into some of the grandest mountain crests of north wales, such as those of cader idris, aran mowddwy, arenig and moel wyn. a similar series is also represented in ireland, ranging from wicklow to waterford, forming a double group of felstones, porphyries, breccias, and ash-beds, with dykes of basalt and dolerite. the same series again appears amidst the lower silurian beds of co. louth, near drogheda. _metamorphic series presumably of lower silurian age._--if, as seems highly probable, the great metamorphic series of donegal and derry are the representatives in time of the lower silurian series, some of the great sheets of felspathic and hornblendic trap which they contain are referable to this epoch. these rocks have undergone a change in structure along with the sedimentary strata of which they were originally formed, so that the sheets of (presumably) augitic lava have been converted into hornblende-rock and schist. similar masses occur in north mayo, south of belderg harbour. _cambrian period._--in the pass of llanberis, along the banks of llyn padarn, masses of quartz-porphyry, felsite and agglomerate, or breccia, indicate volcanic action during this stage. these rocks underlie beds of conglomerate, slate and grit of the lower cambrian epoch, and, as mr. blake has shown, are clearly of volcanic origin, and pass upwards into the sedimentary strata of the period. a similar group, first recognised by professor sedgwick, stretches southwards from bangor along the southern shore of the menai straits. again, we find the volcanic eruptions of this epoch at st. david's, consisting of diabasic and felsitic lava, with beds of ash; and in the centre of england, amongst the grits and slates of charnwood forest presumably of cambrian age, various felstones, porphyries, and volcanic breccias are found. thus it will be seen that every epoch, from the earliest stage of the cambrian to the permian, in the british isles, gives evidence of the existence of volcanic action; from which we may infer that the originating cause, whatever it may be, has been in operation throughout all past geological time represented by living forms. the question of the condition of our globe in archæan times, and earlier, is one which only can be discussed on theoretic ground, and is beyond the scope of this work. [ ] the reader is referred to sir a. geikie's presidential address to the geological society ( ) for the latest view of this subject. [illustration: volcanic band of the moluccas. map showing the volcanic belt to which krakatoa belongs. the shaded portion is volcanic.] part vi. special volcanic and seismic phenomena. chapter i. the eruption of krakatoa in . i propose to introduce here some account of one of the most terrible outbursts of volcanic action that have taken place in modern times; namely, the eruption of the volcano of krakatoa (a corruption of rakata) in the strait of sunda, between the islands of sumatra and java, in the year . the malay archipelago, of which this island once formed a member, is a region where volcanic action is constant, and where the outbursts are exceptionally violent. with the great island of borneo as a solid, non-volcanic central core, a line of volcanic islands extends from chedooba off the coast of pegu through sumatra, java, sumbawa, flores, and, reaching the moluccas, stretches northwards through the philippines into japan and kamtschatka. this is probably the most active volcanic belt in the world, and the recent terrible earthquake and eruption in japan (november, ) gives proof that the volcanic forces are as powerful and destructive as ever.[ ] (_a._) _dormant condition down to ._--down to the year , this island, although from its form and structure evidently volcanic, appears to have been in a dormant state; its sides were covered with luxuriant forests, and numerous habitations dotted its shore. but in may of that year an eruption occurred, owing to which the aspect of krakatoa as described by vogel was entirely changed; the surface of the island when this writer passed on his voyage to sumatra appeared burnt up and arid, while blocks of incandescent rock were being hurled into the air from four distinct points. after this first recorded eruption the island relapsed into a state of repose, and except for a stream of molten lava which issued from the northern extremity, there was no evidence of its dangerous condition. the luxuriant vegetation of the tropics speedily re-established itself, and the volcano was generally regarded as "extinct."[ ] history repeats itself; and the history of vesuvius was repeated in the case of krakatoa. [illustration: fig. .--map of the krakatoa group of islands before the eruption of august (from admiralty chart)] (_b._) _eruption of may, ._[ ]--on the morning of may , , the inhabitants of batavia, of buitenzorg, and neighbouring localities, were surprised by a confused noise, mingled with detonations resembling the firing of artillery. the phenomena commenced between ten and eleven o'clock in the morning, and soon acquired such intensity as to cause general alarm. the detonations were accompanied by tremblings of the ground, of buildings and various objects contained in dwellings; but it was generally admitted that these did not proceed from earthquake shocks, but from atmospheric vibrations. no deviation of the magnetic needle was observed at the meteorological institute of batavia; but a vertical oscillation was apparent, and persons who listened with the ear placed on the ground, even during the most violent detonations, could hear no subterranean noise whatever. it became clear that the sounds came from some volcano burst into activity; but it is strange that for two whole days it remained uncertain what was the particular volcano to which the phenomena were to be referred. the detonations appeared, indeed, to come from the direction of krakatoa; but from serang, anjer, and merak, localities situated much nearer krakatoa than batavia, the telegraph announced that neither detonations nor atmospheric vibrations had been perceived. the distance between batavia and krakatoa is ninety-three english miles. the doubts thus experienced were, however, soon put to rest by the arrival of an american vessel under the command of a. r. thomas, and of other ships which hailed from the straits of sunda. from their accounts it was ascertained that in the direction of krakatoa the heavens were clouded with ashes, and that a grand column of smoke, illumined from time to time by flashes of flame, arose from above the island. thus after a repose of more than two hundred years, "the peaceable isle of krakatoa, inhabited, and covered by thick forests, was suddenly awakened from its condition of fancied security." [illustration: fig. .--section from verlaten island through krakatoa, to show the outline before and after the eruption of august, . the continuous line shows the former; the dotted line and shading, the latter; from which it will be observed that the original island has to a large extent disappeared. the line of section is shown in fig. .] (_c._) _form and appearance of the island before the eruption of ._--from surveys made in and , it would appear that the island of krakatoa consisted of three mountains or groups of mountains (figs. , ); the southern formed by the cone of rakata (properly so called), rising with a scarped face above the sea to a height of over mètres ( , feet). adjoining this cone, and rising from the centre of the island, came the group of danan, composed of many summits, probably forming part of the _enceinte annulaire_ of a crater. and near the northern extremity of the isle, a third group of mammelated heights could be recognised under the general name of perboewatan, from which issued several obsidian lava-flows, with a steep slope; these dated back perhaps to the period of the first known eruption of . this large and mountainous island as it existed at the beginning of may, , has been entirely destroyed by the terrible eruptions of that year, with the exception of the peripheric rim (composed of the most ancient of the volcanic rocks, andesite), of which verlaten island and rakata formed a part, and one very small islet, which is noted on the maps as "rots" (rock), and on the new map of the straits of sunda of the dutch navy as that of "bootsmansrots."[ ] as shown by the map in the report of the royal society, the group of islands which existed previous to were but the unsubmerged portions of one vast volcanic crater, built up of a remarkable variety of lava allied to the andesite of the java volcanoes, but having a larger percentage of silica, and hence falling under the head of "enstatite-dacite."[ ] that these volcanic rocks are of very recent origin is shown by the fact, ascertained by verbeek, that beneath them occur deposits of post-tertiary age, and that these in turn rest on the tertiary strata which are widely distributed through sumatra, java, and the adjoining islands. according to the reasoning of professor judd, the krakatoa group at an early period of its history presented the form of a magnificent crater-cone, several miles in circumference at the base, which subsequent eruptions shattered into fragments or blew into the air in the form of dust, ashes, and blocks of lava, while the central part collapsed and fell in, leaving a vast circular ring like the ancient crater of somma (see fig. , p. ), and he supposes the former eruptions to have been on a scale exceeding in magnificence those which have caused such world-wide interest within the last few years. (_d._) _eruption of th to th of august._--it was, as we have seen, in the month of may that, in the language of chev. verbeek, "the volcano of krakatoa chose to announce in a high voice to the inhabitants of the archipelago that, although almost nothing amongst the many colossal volcanic mountains of the indies, it yielded to none of them in regard to its power." these eruptions were, however, only premonitory of the tremendous and terrible explosion which was to commence on sunday, the th of august, and which continued for several days subsequently. a little after noon of that day, a rumbling noise accompanied by short and feeble explosions was heard at buitenzorg, coming from the direction of krakatoa; and similar sounds were heard at anjer and batavia a little later. soon these detonations augmented in intensity, especially about five o'clock in the evening; and news was afterwards received that the sounds had been heard in the isle of java. these sounds increased still more during the night, so that few persons living on the west side of the isle of java were able to sleep. at seven in the morning there came a crash so formidable, that those who had hoped for a little sleep at buitenzorg leaped from their beds. meanwhile the sky, which had up to this time been clear, became overcast, so that by ten o'clock it became necessary to have recourse to lamps, and the air became charged with vapour. occasional shocks of earthquake were now felt. darkness became general all over the straits and the bordering coasts. showers of ashes began to fall. the repeated shocks of earthquake, and the rapid discharges of subterranean artillery, all combined to show that an eruption of even greater violence than that of may was in progress at the isle of krakatoa. but the most interested witnesses to this terrible outburst were those on board the ships plying through the straits. amongst these was the _charles bal_, a british vessel under the command of captain watson. this ship was ten miles south of the volcano on sunday afternoon, and therefore well in sight of the island at the time when the volcano had entered upon its paroxysmal state of action. captain watson describes the island as being covered by a dense black cloud, while sounds like the discharges of artillery occurred at intervals of a second of time; and a crackling noise (probably arising from the impact of fragments of rock ascending and descending in the atmosphere) was heard by those on board. these appearances became so threatening towards five o'clock in the evening, that the commander feared to continue his voyage and began to shorten sail. from five to six o'clock a rain of pumice in large pieces, quite warm, fell upon the ship, which was one of those that escaped destruction during this terrible night.[ ] (_e._) _electrical phenomena._--during this eruption, electrical phenomena of great splendour were observed. captain wooldbridge, viewing the eruption in the afternoon of the th from a distance of forty miles, speaks of a great vapour-cloud looking like an immense wall being momentarily lighted up "by bursts of forked lightning like large serpents rushing through the air. after sunset this dark wall resembled a blood-red curtain, with edges of all shades of yellow, the whole of a murky tinge, through which gleamed fierce flashes of lightning." as professor judd observes, the abundant generation of atmospheric electricity is a familiar phenomenon in all volcanic eruptions on a grand scale. the steam-jets rushing through the orifices of the earth's crust constitute an enormous hydro-electrical engine, and the friction of the ejected materials striking against one another in their ascent and descent also does much in the way of generating electricity.[ ] it has been estimated by several observers that the column of watery vapour ascended to a height of from twelve to seventeen and even twenty-three miles; and on reaching the upper strata of the atmosphere, it spread itself out in a vast canopy resembling "the pine-tree" form of vesuvian eruptions; and throughout the long night of the th this canopy continued to extend laterally, and the particles of dust which it enclosed began to descend slowly through the air. (_f._) _formation of waves._--this tremendous outburst of volcanic forces, which to a greater or less extent influenced the entire surface of the globe, gave rise to waves which traversed both air and ocean; and in consequence of the large number of observatories scattered all over the globe, and the excellence and delicacy of the instruments of observation, we are put in possession of the remarkable results which have been obtained from the collection of the observations in the hands of competent specialists. the results are related _in extenso_ in the report of the royal society, illustrated by maps and diagrams, and are worthy of careful study by those interested in terrestrial phenomena. a brief summary is all that can be given here, but it will probably suffice to bring home to the reader the magnitude and grandeur of the eruption. the vibrations or waves generated in august, , at krakatoa may be arranged under three heads: ( ) atmospheric waves; ( ) sound waves; and ( ) oceanic waves; which i will touch upon in the order here stated. ( ) _atmospheric waves._--these phenomena have been ably handled by general strachey,[ ] from a large number of observations extending all over the globe. from these it has been clearly established that an atmospheric wave, originating at krakatoa as a centre, expanded outwards in a circular form and travelled onwards till it became a great circle at a distance of degrees from its point of origin, after which it still advanced, but now gradually contracting to a node at the antipodes of krakatoa; that is to say, at a point over the surface of north america, situated in lat. ° n. and long. ° w. (or thereabout). having attained this position, the wave was reflected or reproduced, expanding outwards for degrees and travelling backwards again to krakatoa, from which it again started, and returning to its original form again overspread the globe. this wonderful repetition, due to the spherical form of the earth, was observed no fewer than seven times, though with such diminished force as ultimately to be outside the range of observation by the most sensitive instruments. it is one of the triumphs of modern scientific appliances that the course of such a wave, generated in a fluid surrounding a globe, which might be demonstrated on mathematical principles, has been actually determined by experiments carried on over so great an area. ( ) _sound waves._--if the sound-waves produced at the time of maximum eruption were not quite as far-reaching as those of the air, they were certainly sufficiently surprising to be almost incredible, were it not that they rest, both as regards time and character, upon incontestible authority. the sound of the eruption, resembling that of the discharge of artillery, was heard not only over nearly all parts of sumatra, java, and the coast of borneo opposite the straits of sunda, but at places over two thousand miles distant from the scene of the explosions. detailed accounts, collected with great care, are given in the report of the royal society, from which the following are selected as examples:-- . at the port of acheen, at the northern extremity of sumatra, distant , miles, it was supposed that the port was being attacked, and the troops were put under arms. . at singapore, distant miles, two steamers were dispatched to look out for the vessel which was supposed to be firing guns as signals of distress. . at bankok, in siam, distant , miles, the report was heard on the th; as also at labuan, in borneo, distant , miles. . at places in the philippine islands, distant about , miles, detonations were heard on the th, at the time of the eruption. the above places lie northwards of krakatoa. in the opposite direction, we have the following examples:-- . at perth, in western australia, distant , miles, sounds as of guns firing at sea were heard; and at the victorian plains, distant about , miles, similar sounds were heard. . in south australia, at alice's springs, undoolga, and other places at distances of over , miles, the sounds of the eruption were also heard. . in a westerly direction at dutch bay, ceylon, distant , miles, the sounds were heard between a.m. and a.m. on the morning of the th of august. . lastly, at the chagos islands, distant , miles, the detonations were audible between and a.m. of the same day. some of the above distances are so great that we may fail to realise them; but they will be more easily appreciated, perhaps, if we change the localities to our own side of the globe, and take two or three cases with similar distances. then, if the eruption had taken place amongst the volcanoes of the canaries, the detonations would have been heard at gibraltar, at lisbon, at portsmouth, southampton, cork, and probably at dublin and liverpool; or, again, supposing the eruption had taken place on the coast of iceland, the report would have been heard all over the western and northern coasts of the british isles, as well as at amsterdam and the hague. the enormous distance to which the sound travelled in the case of krakatoa was greatly due to the fact that the explosions took place at the surface of the sea, and the sound was carried along that surface uninterruptedly to the localities recorded; a range of mountains intervening would have cut off the sound-wave at a comparatively short distance from its source. ( ) _oceanic waves._--as may be supposed, the eruption gave rise to great agitation of the ocean waters with various degrees of vertical oscillation; but according to the conclusions of captain wharton, founded on numerous data, the greatest wave seems to have originated at krakatoa about a.m. on the th of august, rising on the coasts of the straits of sunda to a height of fifty feet above the ordinary sea-level. this wave appears to have been observed over at least half the globe. it travelled westwards to the coast of hindostan and southern arabia, ultimately reaching the coasts of france and england. eastwards it struck the coast of australia, new zealand, the sandwich islands, alaska, and the western coast of north america; so that it was only the continent of north and south america which formed a barrier (and that not absolute) to the circulation of this oceanic wave all over the globe. the destruction to life and property caused by this wave along the coasts of sunda was very great. combined with the earthquake shocks (which, however, were not very severe), the tremendous storm of wind, the fall of ashes and cinders, and the changes in the sea-bed, it produced in the straits of sunda for some time after the eruption a disastrous transformation. lighthouses had been swept away; all the old familiar landmarks on the shore were obscured by a vast deposit of volcanic dust; the sea itself was encumbered with enormous quantities of floating pumice, in many places of such thickness that no vessel could force its way through them; and for months after the eruption one of the principal channels was greatly obstructed by two islands which had arisen in its midst. the sebesi channel was completely blocked by banks composed of volcanic materials, and two portions of these banks rose above the sea as islands, which received the name of "steers island" and "calmeyer island"; but these, by the action of the waves, have since been completely swept away, and the materials strewn over the bed of the sea.[ ] (_g._) _atmospheric effects._--but the face of nature, even in her most terrific and repulsive aspect, is seldom altogether unrelieved by some traces of beauty. in contrast to the fearful and disastrous phenomena just described, is to be placed the splendour of the heavens, witnessed all over the central regions of the globe throughout a period of several months after the eruption of , which has been ably treated by the hon. rollo russell and mr. c. d. archibald, in the royal society's report. when the particles of lava and ashes mingled with vapour were projected into the air with a velocity greater than that of a ball discharged from the largest armstrong gun, these materials were carried by the prevalent trade-winds in a westerly direction, and some of them fell on the deck of ships sailing in the indian ocean as far as long. ° e., as in the case of the _british empire_--on which the particles fell on the th of august, at a distance of , miles from krakatoa. but far beyond this limit, the finer particles of dust (or rather minute crystals of felspar and other minerals), mingled with vapour of water, were carried by the higher currents of the air as far as the seychelles and africa,--not only the east coast, but also the west, as cape coast castle on the gold coast; to paramaribo, trinidad, panama, the sandwich isles, ceylon and british india, at all of which places during the month of september the sun assumed tints of blue or green, as did also the moon just before and after the appearance of the stars;[ ] and from the latter end of september and for several months, the sky was remarkable for its magnificent coloration; passing from crimson through purple to yellow, and melting away in azure tints which were visible in europe and the british isles; while a large corona was observed round both the sun and moon. these beautiful sky effects were objects of general observation throughout the latter part of the year and commencement of the following year. the explanation of these phenomena may be briefly stated. the fine particles, consisting for the most part of translucent crystals, or fragments of crystals, formed a canopy high up in the atmosphere, being gradually spread over both sides of the equator till it formed a broad belt, through which the rays of the sun and moon were refracted. towards dawn and sunset they were refracted and reflected from the facets of the crystal, and thus underwent decomposition into the prismatic colours; as do the rays of the sun when refracted and reflected from the particles of moisture in a rain-cloud. the subject is one which cannot be fully dealt with here, and is rather outside the scope of this work. (_h._) _origin of the eruption._--the ultimate cause of volcanic eruptions is treated in a subsequent chapter, nor is that of krakatoa essentially different from others. it was remarkable, however, both for the magnitude of the forces evoked and the stupendous scale of the resulting phenomena. it is evident that water played an important part in these phenomena, though not as the prime mover;--any more than water in the boiler of a locomotive is the prime mover in the generation of the steam. without the fuel in the furnace the steam would not be produced; and the amount of steam generated will be proportional to the quantity and heat of the fuel in the furnace and the quantity of water in the boiler. in the case of krakatoa, both these elements were enormous and inexhaustible. the volcanic chimney (or system of chimneys), being situated on an island, was readily accessible to the waters of the ocean when fissures gave them access to the interior molten matter. that such fissures were opened we may well believe. the earthquakes which occurred at the beginning of may, and later on, on the th of that month, may indicate movements of the crust by which water gained access. it appears that in may the only crater in a state of activity was that of perboewatan; in june another crater came into action, connected with danan in the centre of the island, and in august a third burst forth. thus there was progressive activity up to the commencement of the grand eruption of the th of that month.[ ] during this last paroxysmal stage, the centre of the island gave way and sunk down, when the waters of the ocean gained free access, and meeting with the columns of molten matter rising from below originated the prodigious masses of steam which rose into the air. (_i._) _cause of the detonations._--the detonations which accompanied the last great eruption are repeatedly referred to in all the accounts. these may have been due, not only to the sudden explosions of steam directly produced by the ocean water coming in contact with the molten lava, but by dissociation of the vapour of water at the critical point of temperature into its elements of oxygen and hydrogen; the reunion of these elements at the required temperature would also result in explosions. the phenomena attending this great volcanic eruption, so carefully tabulated and critically examined, will henceforth be referred to as constituting an epoch in the history of volcanic action over the globe, and be of immense value for reference and comparison. [ ] the eruption of krakatoa has been the subject of an elaborate report published by the royal society, and is also described in a work by chevalier r. d. m. verbeek, ingenieur en chef des mines, and published by order of the governor-general of the netherland indies ( ). see also an article by sir r. s. ball in the _contemporary review_ for november, . [ ] verbeek, _loc. cit._, p. . [ ] the account of this eruption is a free translation from verbeek. [ ] verbeek, _loc. cit._, p. . [ ] judd, _rep. r. s._ [ ] a fuller account by prof. judd will be found in the _report of the royal society_, p. . several vessels at anchor were driven ashore on the straits owing to the strong wind which arose. [ ] judd, _report_, p. . [ ] _report_, part ii. [ ] in this eruption, , human beings perished, of whom were europeans; villages (_kampoengs_) were entirely, and partially, destroyed.--verbeek, _loc. cit._, p. . [ ] verbeek, _loc. cit._, p. - . the dust put a girdle round the earth in thirteen days. [ ] verbeek, _loc. cit._, p. . chapter ii. earthquakes. _connection of earthquakes with volcanic action._--the connection between earthquake shocks and volcanic eruptions is now so generally recognised that it is unnecessary to insist upon it here. all volcanic districts over the globe are specially liable to vibrations of the crust; but at the same time it is to be recollected that these movements visit countries occasionally from which volcanoes, either recent or extinct, are absent; in which cases we may consider earthquake shocks to be abortive attempts to originate volcanic action. (_a._) _origin._--from the numerous observations which have been made regarding the nature of these phenomena by hopkins, lyell, and others, it seems clearly established that earthquakes have their origin in some sudden impact of gas, steam, or molten matter impelled by gas or steam under high pressure, beneath the solid crust.[ ] how such impact originates we need not stop to inquire, as the cause is closely connected with that which produces volcanic eruptions. the effect, however, of such impact is to originate a wave of translation through the crust, travelling outwards from the point, or focus, on the surface immediately over the point of impact.[ ] these waves of translation can in some cases be laid down on a map, and are called "isoseismal curves," each curve representing approximately an equal degree of seismal intensity; as shown on the chart of a part of north america affected by the great charleston earthquake. (fig. .) mr. hopkins has shown that the earthquake-wave, when it passes through rocks differing in density and elasticity, changes in some degree not only its velocity, but its direction; being both refracted and reflected in a manner analogous to that of light when it passes from one medium to another of different density.[ ] when a shock traverses the crust through a thickness of several miles it will meet with various kinds of rock as well as with fissures and plications of the strata, owing to which its course will be more or less modified. (_b._) _formation of fissures._--during earthquake movements, fissures may be formed in the crust, and filled with gaseous or melted matter which may not in all cases reach the surface; and, on the principle that volcanoes are safety-valves for regions beyond their immediate influence, we may infer that the earthquake shock, which generally precedes the outburst of a volcano long dormant, finds relief by the eruption which follows; so that whatever may be the extent of the disastrous results of such an eruption, they would be still more disastrous if there had been no such safety-valve as that afforded by a volcanic vent. thus, probably, owing to the extinction of volcanic activity in syria, the earthquakes in that region have been peculiarly destructive. for example, on january , , the town of safed west of the jordan valley was completely destroyed by an earthquake in which most of the inhabitants perished. the great earthquakes of aleppo in the present century, and of syria in the middle of the eighteenth, were of exceptional severity. in that of syria, which took place in , and which was protracted during a period of three months, an area of , square leagues was affected. accon, saphat, baalbeck, damascus, sidon, tripoli, and other places were almost entirely levelled to the ground; many thousands of human beings lost their lives.[ ] other examples might be cited. (_c._) _earthquake waves._--we have now to return to the phenomena connected with the transmission of earthquake-waves. the velocity of transmission through the earth is very great, and several attempts have been made to measure this velocity with accuracy. the most valuable of such attempts are those connected with the charleston and riviera shocks. fortunately, owing to the perfection of modern appliances, and the number of observers all over the globe, these results are entitled to great confidence. the phenomena connected with the charleston earthquake, which took place on the st of august, , are described in great detail by captain clarence e. dutton, of the u.s. ordnance corps.[ ] the conclusions arrived at are;--that as regards the depth of the focal point, this is estimated at twelve miles, with a probable error of less than two miles; while, as regards the rate of travel of the earthquake-wave, the estimate is (in one case) about . miles per second; and in another about . miles per second. on the other hand, in the case of the earthquake of the riviera, which took place on the rd of february, , at . a.m. (local time), the vibrations of which appear to have extended across the atlantic, and to have sensibly affected the seismograph in the government signal office at washington, the rate of travel was calculated at about miles per hour, less than one-half that determined in the case of charleston; but captain dutton claims, and probably with justice, that the results obtained in the latter case are far more reliable than any hitherto arrived at. (_d._) _oceanic waves._--when the originating impact takes place under the bed of the ocean--either by a sudden up-thrust of the crust to the extent, let us suppose, of two or three feet, or by an explosion from a submarine volcano--a double wave is formed, one travelling through the crust, the other through the ocean; and as the rate of velocity of the former is greatly in excess of that of the latter, the results on their reaching the land are often disastrous in the extreme. it is the ocean-wave, however, which is the more important, and calls for special consideration. if the impact takes place in very deep water, the whole mass of the water is raised in the form of a low dome, sloping equally away in all directions; and it commences to travel outwards as a wave with an advancing crest until it approaches the coast and enters shallow water. the wave then increases in height, and the water in front is drawn in and relatively lowered; so that on reaching a coast with a shelving shore the form of the surface consists of a trough in front followed by an advancing crest. these effects may be observed on a small scale in the case of a steamship advancing up a river, or into a harbour with a narrow channel, but are inappreciable in deep water, or along a precipitous open coast. (_e._) _the earthquake of lisbon, ._--the disastrous results of a submarine earthquake upon the coast have never been more terribly illustrated than in the case of the earthquake of lisbon which took place on november , . the inhabitants had no warning of the coming danger, when a sound like that of thunder was heard underground, and immediately afterwards a violent shock threw down the greater part of their city; this was the land-wave. in the course of about six minutes, sixty thousand persons perished. the sea first retired and left the harbour dry, so forming the trough in front of the crest; immediately after the water rolled in with a lofty crest, some feet above the ordinary level, flooding the harbour and portions of the city bordering the shore. the mountains of arrabida, estrella, julio, marvan, and cintra, were impetuously shaken, as it were, from their very foundations; and according to the computation of humboldt, a portion of the earth's surface four times the extent of europe felt the effects of this great seismic shock, which extended to the alps, the shores of the baltic, the lakes of scotland, the great lakes of north america, and the west indian islands. the velocity of the sea-wave was estimated at about miles per minute. (_f._) _earthquake of lima and callao, th october, ._--of somewhat similar character was the terrible catastrophe with which the cities of lima and callao were visited in the middle of the last century,[ ] in which the former city, then one of great magnificence, was overthrown; and callao was inundated by a sea-wave, in which out of ships of all sizes in the harbour the greater number foundered; several, including a man-of-war, were lifted bodily and stranded, and all the inhabitants with the exception of about two hundred were drowned. a volcano in lucanas burst forth the same night, and such quantities of water descended from the cone that the whole country was overflowed; and in the mountain near pataz, called conversiones de caxamarquilla, three other volcanoes burst forth, and torrents of water swept down their sides. in the case of these cities, the land-wave, or shock, preceded the sea-wave, which of course only reached the port of callao. [illustration: fig. .--the lines represent isoseismal curves, or curves of equal intensity, the force decreasing outwards from the focus at charleston, no. .] (_g._) _earthquake of charleston, st august, ._--i shall close this account of some remarkable earthquakes with a few facts regarding that of charleston, on the atlantic seaboard of carolina.[ ] at . a.m. of this day, the inhabitants engaged in their ordinary occupations were startled by the sound of a distant roar, which speedily deepened in volume so as to resemble the noise of cannon rattling along the road, "spreading into an awful noise, that seemed to pervade at once the troubled earth below and the still air above." at the same time the floors began to heave underfoot, the walls visibly swayed to and fro, and the crash of falling masonry was heard on all sides, while universal terror took possession of the populace, who rushed into the streets, the black portion of the community being the most demonstrative of their terror. such was the commencement of the earthquake, by which nearly all the houses of charleston were damaged or destroyed, many of the public buildings seriously injured or partially demolished. the effects were felt all over the states as far as the great lakes of canada and the borders of the rocky mountains. two epicentral _foci_ appear to have been established; one lying about miles to the n.w. of charleston, called the _woodstock focus_; the other about miles due west of charleston, called the _rantowles focus_; around each of these _foci_ the isoseismic curves concentrated,[ ] but in the map (fig. ) are combined into the area of one curve. the position of these _foci_ clearly shows that the origin of the charleston earthquake was not submarine, though occurring within a short distance of the atlantic border; the curves of equal intensity (isoseismals) are drawn all over the area influenced by the shock. as a general result of these detailed observations, captain dutton states that there is a remarkable coincidence in the phenomena with those indicated by the theory of wave-motion as the proper one for an elastic, nearly homogeneous, solid medium, composed of such materials as we know to constitute the rocks of the outer portions of the earth; but on the other hand he states that nothing has been disclosed which seems to bring us any nearer to the precise nature of the forces which generated the disturbance.[ ] [ ] the views of mr. r. mallet, briefly stated, are somewhat as follows:--owing to the secular cooling of the earth, and the consequent lateral crushing of the surface, this crushing from time to time overcomes the resistance; in which case shocks are experienced along the lines of fracture and faulting by which the crust is intersected. these shocks give rise to earthquake waves, and as the crushing of the walls of the fissure developes heat, we have here the _vera causa_ both of volcanic eruptions and earthquake shocks--the former intensified into explosions by access of water through the fissures.--"on the dynamics of earthquakes," _trans. roy. irish acad._, vol. xxi. [ ] illustration of the mode of propagation of earthquake shocks will be found in lyell's _principles of geology_, vol. ii. p. , or in the author's _physiography_, p. , after hopkins. [ ] "rep. on theories of elevation and earthquakes," _brit. ass. rep._ , p. . in the map prepared by prof. j. milne and mr. w. k. burton to show the range of the great earthquake of japan ( ), similar isoseismal lines are laid down. [ ] lyell, _loc. cit._, p. . two catalogues of earthquakes have been drawn up by prof. o'reilly, and are published in the _trans. roy. irish academy_, vol. xxviii. ( and ). [ ] _ninth annual report, u.s. geological survey_ ( ). [ ] _a true and particular account of the dreadful earthquake_, nd edit. the original published at lima by command of the viceroy. london, . translated from the spanish. [ ] i take the account from that of capt. dutton above cited, p. . [ ] dutton, _report_, plate xxvi., p. . [ ] _ibid._, p. . on the connection between the moon's position and earthquake shocks, see mr. richardson's paper on scottish earthquakes, _trans. edin. geol. soc._, vol. vi. p. ( ). part vii. volcanic and seismic problems. chapter i. the ultimate cause of volcanic action. volcanic phenomena are the outward manifestations of forces deep-seated beneath the crust of the globe; and in seeking for the causes of such phenomena we must be guided by observation of their nature and mode of action. the universality of these phenomena all over the surface of our globe, in past or present times, indicates the existence of a general cause beneath the crust. it is true that there are to be found large tracts from which volcanic rocks (except those of great geological antiquity) are absent, such as central russia, the nubian desert, and the central states of north america; but such absence by no means implies the non-existence of the forces which give rise to volcanic action beneath those regions, but only that the forces have not been sufficiently powerful to overcome the resistance offered by the crust over those particular tracts. on the other hand, the similarity of volcanic lavas over wide regions is strong evidence that they are drawn from one continuous magma, consisting of molten matter beneath the solid exterior crust. (_a._) _lines of volcanic action._--it has been shown in a previous page that volcanic action of recent or tertiary times has taken place mainly along certain lines which may be traced on the surface of a map or globe. one of these lines girdles the whole globe, while others lie in certain directions more or less coincident with lines of flexure, plication or faulting. the isle of sumatra offers a remarkable example of the coincidence of such lines with those of volcanic vents. not only the great volcanic cones, but also the smaller ones, are disposed in chains which run parallel to the longitudinal axis of the island (n.w.-s.e.). the sedimentary rocks are bent and faulted in lines parallel to the main axis, and also to the chains of volcanic mountains, and the observation holds good with regard to different geological periods.[ ] another remarkable case is that of the jordan valley. nowhere can the existence of a great fracture and vertical displacement of the strata be more clearly determined than along this remarkable line of depression; and it is one which is also coincident with a zone of earthquake and volcanic disturbances. (_b._) _such lines generally lie along the borders of the ocean._--but even where, from some special cause, actual observation on the relations of the strata are precluded, the general configuration of the ground and the relations of the boundaries between land and sea to those of volcanic chains, evidently point in many cases to their mutual interdependence. the remarkable straightness of the coast of western america, and of the parallel chain of the andes, affords presumptive evidence that this line is coincident with a fracture or system of faults, along which the continent has been bodily raised out of the waters of the ocean. of this elevation within very recent times we have abundant evidence in the existence of raised coral-reefs and oceanic shell-beds at intervals all along the coast; rising in peru to a level of no less than , feet above the ocean, as shown by alexander agassiz.[ ] such elevations probably occurred at a time when the volcanoes of the andes were much more active than at present. considered as a whole, these great volcanic mountains may be regarded as in a dormant, or partially moribund, condition; and if the volcanic forces have to some extent lost their strength, so it would appear have those of elevation. (_c._) _areas of volcanic action in the british isles._--in the case of the british islands it may be observed that the later tertiary volcanic districts lie along very ancient depressions, which may indicate zones of weakness in the crust. thus the antrim plateau, as originally constituted, lay in the lap of a range of hills formed of crystalline, or lower silurian, rocks; while the volcanic isles of the inner hebrides were enclosed between the solid range of the archæan rocks of the outer hebrides on the one side, and the silurian and archæan ranges of the mainland on the other. and if we go back to the carboniferous period, we find that the volcanic district of the centre of scotland was bounded by ranges of solid strata both to the north and south, where the resistance to interior pressure from molten matter would have been greater than in the carboniferous hollow-ground, where such molten matter has been abundantly extruded. in all these cases, the outflow of molten matter was in a direction somewhat parallel to the plications of the strata. (_d._) _special conditions under which the volcanic action operates._--assuming, then, that the molten matter, forming an interior magma or shell, is constantly exerting pressure against the inner surface of the solid crust, and can only escape where the crust is too weak (owing to faults, plications, or fissures) to resist the pressure, we have to inquire what are the special conditions under which outbursts of volcanic matter take place, and what are the general results as regards the nature of the _ejecta_ dependent on those conditions. (_e._) _effect of the presence or absence of water._--the two chief conditions determining the nature of volcanic products, considered in the mass, are the presence or absence of water. such presence or absence does not of course affect the essential chemical composition of the _ejecta_, but it materially influences the form in which the matter is erupted. the agency of water in volcanic eruptions is a very interesting and important subject in connection with the history of volcanic action, and has been ably treated by professor prestwich.[ ] at one time it was considered that water was essential to volcanic activity; and the fact that the great majority of volcanic cones are situated in the vicinity of the oceanic waters, or of inland seas, was pointed to in confirmation of this theory. but the existence in western america and other volcanic countries of fissures of eruption along which molten lava has been extruded without explosions of steam, shows that water is not an essential factor in the production of volcanic phenomena; and, as professor prestwich has clearly demonstrated, it is to be regarded as an element in volcanic explosions, rather than as a prime cause of volcanic action. the main difficulty he shows to be thermo-dynamical; and calculating the rate of increase in the elastic force of steam on descending to greater and greater depths and reaching strata of higher and higher temperatures, as compared with the force of capillarity, he comes to the conclusion that water cannot penetrate to depths of more than seven or eight miles, and therefore cannot reach the seat of the eruptive forces. professor prestwich also points out that if the extrusion of lava were due to the elastic force of vapour of water there should be a distinct relation between the discharge of the lava and of the vapour; whereas the result of an examination of a number of well-recorded eruptions shows that the two operations are not related, and are, in fact, perfectly independent. sometimes there has been a large discharge of lava, and little or no escape of steam; at other times there have been paroxysmal explosive eruptions with little discharge of lava. even in the case of vesuvius, which is close to the sea, there have been instances when the lava has welled out almost with the tranquillity of a water-spring. (_f._) _access of surface water to molten lava during eruptions._--the existence of water during certain stages in eruptions is too frequent a phenomena to be lost sight of; but its presence may be accounted for in other ways, besides proximity to the sea or ocean. certain volcanic mountains, such as etna and vesuvius, are built upon water-bearing strata, receiving their supplies from the rainfall of the surrounding country, or perhaps partly from the sea. in addition to this the ashes and scoriæ of the mountain sides are highly porous, and rain or snow can penetrate and settle downwards around the pipe or throat through which molten lava wells up from beneath. in such cases it is easy to understand how, at the commencement of a period of activity, molten lava ascending through one or more fissures, and meeting with water-charged strata or scoriæ, will convert the water into steam at high pressure, resulting in explosions more or less violent and prolonged, in proportion to the quantity of water and the depth to which it has penetrated. in this manner we may suppose that ashes, scoriæ, and blocks of rock torn from the sides of the crater-throat, and hurled into the air, are piled around the vent, and accumulate into hills or mountains of conical form. after the explosion has exhausted itself, the molten lava quietly wells up and fills the crater, as in the cases of those of auvergne and syria, and other places. we may, therefore, adopt the general principle that in volcanic eruptions _where water in large quantities is present, we shall have crater-cones built up of ashes, scoriæ, and pumice; but where absent, the lava will be extravasated in sheets to greater or less distances without the formation of such cones; or if cones are fanned, they will be composed of solidified lava only, easily distinguishable from crater-cones of the first class_. (_g._) _nature of the interior reservoir from which lavas are derived._--we have now to consider the nature of the interior reservoir from which lavas are derived, and the physical conditions necessary for their eruption at the surface. without going back to the question of the original condition of our globe, we may safely hold the view that at a very early period of geological history it consisted of a solidified crust at a high temperature, enfolding a globe of molten matter at a still higher temperature. as time went on, and the heat radiated into space from the surface of the globe, while at the same time slowly ascending from the interior by conduction, the crust necessarily contracted, and pressing more and more on the interior molten magma, this latter was forced from time to time to break through the contracting crust along zones of weakness or fissures. (_h._) _the earth's crust in a state of both exterior thrust and of interior tension._--as has been shown by hopkins,[ ] and more recently by mr. davison,[ ] an exterior crust in such a condition must eventually result in being under a state of horizontal thrust towards the exterior and of tension towards the interior surface. for the exterior portion, having cooled down, and consequently contracted to its normal state, will remain rigid up to a certain point of resistance; but the interior portion still continuing to contract, owing to the conduction of the heat towards the exterior, would tend to enter upon a condition of tension, as becoming too small for the interior molten magma; and such a state of tension would tend to produce rupture of the interior part. in this manner fissures would be formed into which the molten matter would enter; and if the fissures happened to extend to the surface, owing to weakness of the crust or flexuring of the strata, or other cause, the molten matter would be extruded either in the form of dykes or volcanic vents. in this way we may account for the numerous dykes of trap by which some volcanic districts are intersected, such as those of the north of ireland and centre of scotland. from the above considerations, it follows that the earth's crust must be in a condition both of pressure (or lateral thrust) towards the exterior portion, and of tension towards the interior, the former condition resulting in faulting and flexuring of the rocks, the latter in the formation of open fissures, through which lava can ascend under high pressure. these operations are of course the attempt of the natural forces to arrive at a condition of equilibrium, which is never attained because the processes are never completed; in other words, radiation and convection of heat are constantly proceeding, giving rise to new forces of thrust and tension. it now remains for us to consider what may be the condition of the interior molten magma; and in doing so we must be guided to a large extent by considerations regarding the nature of the extruded matter at the surface. (_i._) _relative densities of lavas._--now, observation shows that, as bearing on the subject under consideration, lavas occur mainly under two classes as regards their density. the most dense (or basic) are those in which silica is deficient, but iron is abundant; the least dense (or acid) are those which are rich in silica, but in which iron occurs in small quantity. this division corresponds with that proposed by bunsen and durocher[ ] for volcanic rocks, upon the results of analyses of a large number of specimens from various districts. rocks may be thus arranged in groups: ( ) _the basic_ (heavier)--poor in silica, rich in iron; containing silica - per cent. examples: basalt, dolerite, hornblende rock, diorite, diabase, gabbro, melaphyre, and leucite lava. ( ) _the acid_ (lighter)--rich in silica, poor in iron; containing silica - per cent. examples: trachyte, rhyolite, obsidian, domite, felsite, quartz-porphyry, granite. the andesite group forms a connecting link between the highly acid and the basic groups, and there are many varieties of the above which it is not necessary to enumerate. durocher supposes that the molten magmas of these various rocks are arranged in concentric shells within the solid crust in order of their respective densities, those of the lighter density, namely the acid magmas, being outside those of greater density, namely the basic; and this is a view which seems not improbable from a consideration not only of the principle itself, but of the succession of the varieties of lava in many districts. thus we find that acid lavas have been generally extruded first, and basic afterwards--as in the cases of western america, of antrim, the rhine and central france. and if the interior of our globe had been in a condition of equilibrium from the time of the consolidation of the crust to the present, reason would induce us to conclude that the lavas would ultimately have arranged themselves in accordance with the conditions of density beneath that crust. but the state of equilibrium has been constantly disturbed. every fresh outburst of volcanic force, and every fresh extrusion of lava, tends to disturb it, and to alter the relations of the interior viscous or molten magmas. owing to this it happens, as we may suppose, that the order of eruption according to density is sometimes broken, and we find such rocks as granophyre (a variety of andesite) breaking through the plateau-basalts of mull and skye, as explained in a former chapter. notwithstanding such variations, however, the view of durocher may be considered as the most reasonable we can arrive at on a subject which is confessedly highly conjectural. (_j._) _conclusion as regards the ultimate cause of volcanic action_.--notwithstanding, however, the complexity of the subject, and the uncertainties which must attend an inquiry where some of the data are outside the range of our observation, sufficient evidence can be adduced to enable us to arrive at a tolerably clear view of the ultimate cause of volcanic action. so tempting a subject was sure to evoke numerous essays, some of great ingenuity, such as that of mr. mallet; others of great complexity, such as that of dr. daubeny. but more recent consideration and wider observation have tended to lead us to the conclusion that the ultimate cause is the most simple, the most powerful, and the most general which can be suggested; namely, _the contraction of the crust due to secular cooling of the more deeply seated parts by conduction and radiation of heat into space_. owing to this cause, the enclosed molten matter is more or less abundantly extruded from time to time along the lines and vents of eruption, so as to accommodate itself to the ever-contracting crust. nor can we doubt that this process has been going on from the very earliest period of the earth's history, and formerly at a greater rate than at present. when the crust was more highly heated, the radiation and conduction must have been proportionately more rapid. owing to this cause also the contraction of the crust was accelerated. to such irresistible force we owe the wonderful flexuring, folding, and horizontal overthrusting which the rocks have undergone in some portions of the globe--such as in the alps, the highlands of scotland and of ireland, and the alleghannies of america. it is easy to show that the acceleration of the earth's rotation must be a consequence of such contraction; but, after all, this is but one of those compensatory forces of which we see several examples in the world around us. it can also be confidently inferred that at an early period of the earth's history, when the moon was nearer to our planet than at present, the tides were far more powerful, and their effect in retarding the earth's rotation was consequently greater. during this period the acceleration due to contraction was also greater; and the two forces probably very nearly balanced each other. both these forces (those of acceleration and retardation) have been growing weaker down to the present day, though there appears to have been a slight advantage on the side of the retarding force.[ ] [ ] r. d. m. verbeek, _krakatau_, p. ( ); also, j. milne, _the great earthquake of japan_, . [ ] _bull. mus. comp. zool._, vol. iii. [ ] _proc. roy. soc._, no. ( ); also, _rep. brit. assoc._ ( ). [ ] hopkins, _supra cit._, p. . [ ] c. davison and g. h. darwin, _phil. trans._, vol. , p; . [ ] durocher, _ann. des mines_, vol. ii. ( ). [ ] see on this subject the author's _textbook of physiography_ (deacon and co., ), pp. and . chapter ii. lunar volcanoes. the surface of the moon presented to our view affords such remarkable indications of volcanic phenomena of a special kind, that we are justified in devoting a chapter to their consideration. it is very tantalising that our beautiful satellite only permits us to look at and admire one half of her sphere; but it is not a very far-fetched inference if we feel satisfied that the other half bears a general resemblance to that which is presented to the earth. it is scarcely necessary to inform the reader why it is that we never see but one face; still, for the sake of those who have not thought out the subject i may state that it is because the moon rotates on her axis exactly in the time that she performs a revolution round the earth. if this should not be sufficiently clear, let the reader perform a very simple experiment for himself, which will probably bring conviction to his mind that the explanation here given is correct. let him place an orange in the centre of a round table, and then let him move round the table from a starting-point sideways, ever keeping his face directed towards the orange; and when he has reached his starting-point, he will find that he has rotated once round while he has performed one revolution round the table. in this case the performer represents the moon and the orange the earth. now this connection between the earth and her satellite is sufficiently close to be used as an argument (if not as actual demonstration) that the earth and the moon were originally portions of the same mass, and that during some very early stage in the development of the solar system these bodies parted company, to assume for ever after the relations of planet and satellite. at the epoch referred to, we may also suppose that these two masses of matter were in a highly incandescent, if not even gaseous, state; and we conclude, therefore, that having been once portions of the same mass, they are composed of similar materials. this conclusion is of great importance in enabling us to reason from analogy regarding the origin of the physical features on the moon's surface, and for the purpose of comparison with those which we find on the surface of our globe; because it is evident that, if the composition of the moon were essentially different from that of our earth, we should have no basis whatever for a comparison of their physical features. when the moon started on her career of revolution round the earth, we may well suppose that her orbit was much smaller than at present. she was influenced by counteracting forces, those of gravitation drawing her towards the centre of gravity of the earth,[ ] and the centrifugal force, which in the first instance was the stronger, so that her orbit for a lengthened period gradually increased until the two forces, those of attraction and repulsion, came into a condition of equilibrium, and she now performs her revolution round the earth at a mean distance of , miles, in an orbit which is only very slightly elliptical.[ ] how the period of the moon's rotation is regulated by the earth's attraction on her molten lava-sheets, first at the surface, and now probably below the outer crust, has been graphically shown by sir robert ball,[ ] but it cannot be doubted that once the moon was appreciably nearer to our globe than at present. the attraction of her mass produced tides in the ocean of correspondingly greater magnitude, and capable of effecting results, both in eroding the surface and in transporting masses of rock, far beyond the bounds of our every-day experience. of all the heavenly bodies, the sun excepted, the moon is the most impressive and beautiful. as we catch her form, rising as a fair crescent in the western sky after sunset, gradually increasing in size and brilliancy night after night till from her circular disk she throws a full flood of light on our world and then passes through her decreasing phases, we recognise her as "the governor of the night," or in the words of our own poet, when in her crescent phase, "the diadem of night." seen through a good binocular glass, her form gains in rotundity; but under an ordinary telescope with a four-inch objective, she appears like a globe of molten gold. yet all this light is derivative, and is only a small portion of that she receives from the sun. that her surface is a mass of rigid matter destitute of any inherent brilliancy, appears plain enough when we view a portion of her disk through a very large telescope. it was the good fortune of the author to have an opportunity for such a view through one of the largest telescopes in the world. the -inch refractor manufactured by sir howard grubb of dublin, for the vienna observatory, a few years ago, was turned on a portion of the moon's disk before being finally sent off to its destination; and seen by the aid of such enormous magnifying power, nothing could be more disappointing as regards the appearance of our satellite. the sheen and lustre of the surface was now observed no longer; the mountains and valleys, the circular ridges and hollows were, indeed, wonderfully defined and magnified, but the matter of which they seemed to be constituted resembled nothing so much as the pale plaster of a model. one could thus fully realise the fact that the moon's light is only derivative. still we must recollect that the most powerful telescope can only bring the surface of the moon to a distance from us of about miles; and it need not be said that objects seen at such a distance on our earth present very deceptive appearances; so that we gain little information regarding the composition of the moon's crust, or exterior surface, simply from observation by the aid of large telescopes. reasoning from analogy with our globe, we may infer that the exterior shell of the moon consists of crystalline volcanic matter of the highly silicated, or acid, varieties resting upon another of a denser description, rich in iron, and resembling basalt. this hypothesis is hazarded on the supposition that the composition of the matter of the moon's mass resembles in the main that of our globe. during the process of cooling from a molten condition, the heavier lavas would tend to fall inwards, and allow the lighter to come to the surface, and form the outer shell in both cases. thus, the outer crust would resemble the trachytic lavas of our globe, and their pale colour would enable the sun's rays to be reflected to a greater extent than if the material were of the blackness of basalt.[ ] so much for the material. we have now to consider the structure of the moon's surface, and here we find ourselves treading on less speculative and safer ground. all astronomers since the time of schroter seem to be of accord in the opinion that the remarkable features of the moon's surface are in some measure of volcanic origin, and we shall presently proceed to consider the character of these forms more in detail. but first, and as leading up to the discussion of these physical features, we must notice one essential difference between the constitution of the moon and of the earth; namely, the absence of water and of an atmosphere in the case of the moon. the sudden and complete occultation of the stars when the moon's disk passes between them and the place of the observer on the earth's surface, is sufficient evidence of the absence of air; and, as no cloud has ever been noticed to veil even for a moment any part of our satellite's face, we are pretty safe in concluding that there is no water; or at least, if there be any, that it is inappreciable in quantity.[ ] hence we infer that there is no animal or vegetable life on the moon's surface; neither are there oceans, lakes or rivers, snowfields or glaciers, river-valleys or cañons, islands, stratified rocks, nor volcanoes of the kind most prevalent on our own globe. [illustration: fig. .--photograph of the moon's surface (in part) showing the illuminated "spots," and ridges, and the deep hollows. the position of "tycho" is shown near the upper edge, and some of the volcanic craters are very clearly seen near the margin.] now on looking at a photographic picture of the moon's surface (fig. ), we observe that there are enormous dark spaces, irregular in outline, but more or less approaching the circular form, surrounded by steep and precipitous declivities, but with sides sloping outwards. these were supposed at one time to be seas; and they retain the name, though it is universally admitted that they contain no water. some of these hollows are four english miles in depth. the largest of these, situated near the north pole of the moon, is called _mare imbrium_; next to it is _mare serenitatis_; next, _mare tranquilitatis_, with several others.[ ] mare imbrium is of great depth, and from its floor rise several conical mountains with circular craters, the largest of which, _archimedes_, is fifty miles in diameter; its vast smooth interior being divided into seven distinct zones running east and west. there is no central mountain or other obvious internal sign of former volcanic activity, but its irregular wall rises into abrupt towers, and is marked outside by decided terraces.[ ] the mare imbrium is bounded along the east by a range of mountains called the _apennines_, and towards the north by another range called the _alps_; while a third range, that of the _caucasus_, strikes northward from the junction of the two former ranges. several circular or oval craters are situated on, and near to, the crest of these ridges. [illustration: fig. .--a magnified portion of the moon's surface, showing the forms of the great craters with their outer ramparts. the white spot with shadow is a cone rising from the centre of one of the larger craters to a great height and thus becoming illuminated by the sun's light.] but the greater part of the moon's hemisphere is dotted over by almost innumerable circular crater-like hollows; sometimes conspicuously surmounting lofty conical mountains, at other times only sinking below the general outer surface of the lunar sphere. on approaching the margin, these circular hollows appear oval in shape owing to their position on the sphere; and the general aspect of those that are visible leads to the conclusion that there are large numbers of smaller craters too small to be seen by the most powerful telescopes. these cones and craters are the most characteristic objects on the whole of the visible surface, and when highly magnified present very rugged outlines, suggestive of slag, or lava, which has consolidated on cooling, as in the case of most solidified lava-streams on our earth.[ ] one of the most remarkable of these crateriform mountains is that named _copernicus_, situated in a line with the southern prolongation of the apennines. of this mountain sir r. ball says: "it is particularly well known through sir john herschel's drawing, so beautifully reproduced in the many editions of the _outlines of astronomy_. the region to the west is dotted over with innumerable minute craterlets. it has a central, many-peaked mountain about , feet in height. there is good reason to believe that the terracing shown in its interior is mainly due to the repeated alternate rise, partial congealation and retreat of a vast sea of lava. at full moon it is surrounded by radiating streaks."[ ] the view regarding the structure of copernicus here expressed is of importance, as it is probably applicable to all the craters of our satellite. "when the moon is five or six days old," says sir robert ball, "a beautiful group of three craters will be readily found on the boundary line between night and day. these are _catharina_, _cyrillus_, and _theophilus_. catharina is the most southerly of the group, and is more than , feet deep and connected to cyrillus by a wide valley; but between cyrillus and theophilus there is no such connection. indeed cyrillus looks as if its huge surrounding ramparts, as high as mont blanc, had been completely finished when the volcanic forces commenced the formation of theophilus, the rampart of which encroaches considerably on its older neighbour. theophilus stands as a well-defined round crater, about miles in diameter, with an internal depth of , to , feet, and a beautiful central group of mountains, one-third of that height, on its floor. this proves that the last eruptive efforts in this part of the moon fully equalled in intensity those that had preceded them. although theophilus is on the whole the deepest crater we can see in the moon, it has received little or no deformation by secondary eruptions." but perhaps the most remarkable object on the whole hemisphere of the moon is "the majestic tycho," which rises from the surface near the south pole, and at a distance of about / th of the diameter of the sphere from its margin. its depth is stated by ball to be , feet, and its diameter miles. but its special distinction amongst the other volcanic craters lies in the streaks of light which radiate from it in all directions for hundreds and even thousands of miles, stretching with superb indifference across vast plains, into the deepest craters, and over the highest opposing ridges. when the sun rises on tycho these streaks are invisible, but as soon as it has reached a height of ° to ° above the horizon, the rays emerge from their obscurity, and gradually increase in brightness until full moon, when they become the most conspicuous objects on her surface. as yet no satisfactory explanation has been given of the origin of these illuminated rays,[ ] but i may be permitted to add that their form and mode of occurrence are eminently suggestive of gaseous exhalations from the volcano illumined by the sun's rays; and owing to the absence of an atmosphere, spreading themselves out in all directions and becoming more and more attenuated until they cease to be visible. the above account will probably suffice to give the reader a general idea of the features and inferential structure of the moon's surface. that she was once a molten mass is inferred from her globular form; but, according to g. f. chambers, the most delicate measurements indicate no compression at the poles.[ ] that her surface has cooled and become rigid is also a necessary inference; though sir j. herschel considered that the surface still retains a temperature _possibly_ exceeding that of boiling water.[ ] however this may be, it is pretty certain that whatever changes may occur upon her surface are not due to present volcanic action, all evidence of such action being admittedly absent. if, when the earth and moon parted company, their respective temperatures were equal, the moon being so much the smaller of the two would have cooled more rapidly, and the surface may have been covered by a rigid crust when as yet that of the earth may have been molten from heat. hence the rigidity of the moon's surface may date back to an immensely distant period, but she may still retain a high temperature within this crust. having arrived at this stage of our narrative, we are in a position to consider by what means, and under what conditions, the cones and craters which diversify the lunar surface have been developed. in doing so it may be desirable, in the first place, to determine what form of crater on our earth's surface those of the moon do not represent; and we are guided in our inquiry by the consideration of the absence of water on the lunar surface. now there are large numbers of crateriform mountains on our globe in the formation of which water has played an important, indeed essential, part. as we have already seen, water, though not the ultimate cause of volcanic eruptions, has been the chief agent, when in the form of steam at high pressure, in producing the explosions which accompany these eruptions, and in tearing up and hurling into the air the masses of rock, scoriæ, and ashes, which are piled around the vents of eruption in the form of craters during periods of activity. to this class of craters those of etna, vesuvius, and auvergne belong. these mountains and conical hills (the domes excepted) are all built up of accumulations of fragmental material, with occasional sheets and dykes of lava intervening; and where eruptions have taken place in recent times, observation has shown that they are accompanied by outbursts of vast quantities of aqueous vapour, which has been the chief agent (along with various gases) in piling up the circular walls of the crater. it has also been shown that in many instances these crater-walls have been breached on one side, and that streams of molten lava which once occupied the cup to a greater or less height, have poured down the mountain side. hence the form or outline of many of these fragmental craters is crescent-shaped. such breached craters are to be found in all parts of the world, and are not confined to any one district, or even continent, so that they may be considered as characteristic of the class of volcanic crater-cones to which i am now referring. in the case of the moon, however, we fail to observe any decided instances of breached craters, with lava-streams, such as those i have described.[ ] in nearly all cases the ramparts appear to extend continuously round the enclosed depression, solid and unbroken; or at least with no large gap occupying a very considerable section of the circumference. (see fig. .) hence we are led to suspect that there is some essential distinction between the craters on the surface of the moon and the greater number of those on the surface of our earth. it is scarcely necessary to add that the volcanic mountains of the moon offer no resemblance whatever to the dome-shaped volcanic mountains of our globe. if it were otherwise, the lunar mountains would appear as simple luminous points rising from a dark floor, over which they would cast a conical shadow. but the form of the lunar volcanic mountains is essentially different; as already observed, they consist in general of a circular rampart enclosing a depressed floor, sometimes terraced as in the case of copernicus, from which rise one or more conical mountains, which are in effect the later vents of eruption. in our search, therefore, for analogous forms on our own earth, we must leave out the craters and domes of the type furnished by the european volcanoes and their representatives abroad, and have recourse to others of a different type. is there then, we may ask, any type of volcanic mountain on our globe comparable with those on the moon? in all probability there is. if the reader will turn to the description of the volcanoes of the hawaiian group in the pacific, especially that of mauna loa, as given by professor dana and others, and compare it with that of copernicus, he will find that in both cases we have a circular rampart of solid lava enclosing a vast plain of the same material from which rise one or more lava-cones. the interiors in both cases are terraced. so that, allowing for differences in magnitude, it would seem that there is no essential distinction between lunar craters and terrestrial craters of the type of mauna loa. dana calls these hawaiian volcanoes "basaltic," basalt being the prevalent material of which they are formed. those of the moon may be composed of similar material, or otherwise; but in either case we may suppose they are built up of lava, erupted from vents connected with the molten reservoirs of the interior. thus we conclude that they belong to an entirely different type, and have been built up in a different manner, from those represented by etna, vesuvius, and most of the extinct volcanoes of auvergne, the eifel, and of other districts considered in these pages. let us now endeavour to picture to ourselves the stages through which the moon may be supposed to have passed from the time her surface began to consolidate owing to the radiation of her heat into space; for there is every probability that some of the craters now visible on her disk were formed at a very early period of her physical history. when the surface began to consolidate, it must also have contracted; and the interior molten matter, pressed out by the contracting crust, must have been over and over again extruded through fissures produced over the solidified surface, until the solid crust extended over the whole lunar surface, and became of considerable thickness. it is from this epoch that, in all probability, we should date the commencement of what may be termed "the volcanic history" of the moon. we must bear in mind that although the moon's surface had become solid, its temperature may have remained high for a very long period. but the continuous radiation of the surface-heat into space would produce continuous contraction, while the convection of the interior heat would tend to increase the thickness of the outer solid shell; and this, ever pressing with increasing force on the interior molten mass, would result in frequent ruptures of the shell, and the extrusion of molten lava rising from below. hence we may suppose the fissure-eruptions of lava were of frequent occurrence for a lengthened period during the early stage of consolidation of the lunar crust; but afterwards these may be supposed to have given place to eruptions through pipes or vents, resulting in the formation of the circular craters which form such striking and characteristic objects in the physical aspect of our satellite.[ ] it is not to be supposed that the various physical features on the lunar surface have all originated in the same way. the great ranges of mountains previously described may have originated by a process of piling up of immense masses of molten lava extruded from the interior through vents or fissures; while the great hollows (or "seas") are probably due to the falling inwards of large spaces owing to the escape of the interior lava. but it is with the circular craters that we are most concerned. judging from analogy with the lava-craters present on our globe, we must suppose them to be due to the extrusion, and piling up, of lava through central pipes, followed in some cases by the subsidence of the floor of the crater. it seems not improbable that it was in this way the greater number of the circular craters lying around tycho, and dotting so large a space round the margin of the moon, were constructed. (see fig. .) in general they appear to consist of an elevated rim, enclosing a depressed plain, out of which a central cone arises. the rim may be supposed to have been piled up by successive discharges of lava from a central orifice; and after the subsidence of the paroxysm the lava still in a molten condition may have sunk down, forming a seething lake within the vast circular rampart, as in the case of the hawaiian volcanoes. the terraces observable within the craters in some instances have probably been left by subsequent eruptions which have not attained to the level of preceding ones; and where a central crater-cone is seen to rise within the caldron, we may suppose this to have been built up by a later series of eruptions of lava through the original pipe after the consolidation of the interior sea of lava. the mamelons of the isle of bourbon,[ ] and some of the lava-cones of hawaii, appear to offer examples on our earth's surface of these peculiar forms. such are the views of the origin of the physical features of our satellite which their form and inferred constitution appear to suggest. they are not offered with any intention of dogmatising on a subject which is admittedly obscure, and regarding which we have by no means all the necessary data for coming to a clear conclusion. all that can be affirmed is, that there is a great deal to be said in support of them, and that they are to some extent in harmony with phenomena within range of observation on the surface of our earth. the far greater effects of lunar vulcanicity, as compared with those of our globe, may be accounted for to some extent by the consideration that the force of gravity on the surface of the moon is only one-sixth of that on the surface of the earth. hence the eruptive forces of the interior of our satellite have had less resistance to overcome than in the case of our planet; and the erupted materials have been shot forth to greater distances, and piled up in greater magnitude, than with us. we have also to recollect that the abrading action of water has been absent from the moon; so that, while accumulations of matter had been proceeding throughout a prolonged period over its surface, there was no counteracting agency of denudation at work to modify or lessen the effects of the ruptive forces. [ ] correctly speaking, each attracts the other towards its centre of gravity with a force proportionate to its mass, and inversely as the square of the distance; but the earth being by much the larger body, its attraction is far greater than that of the moon. [ ] the variation in the distance is only under rare circumstances , miles, but ordinarily about , miles. [ ] _story of the heavens_, nd edition, p. , _et seq._ [ ] a series of researches made by zöllner, of leipzig, led him to assign to the light-reflecting capacity of the full-moon a result intermediate between that obtained by bouguer, which gave a brightness equal to / part of that of the sun, and of wollaston, which gave / part. we may accept / of zöllner as sufficiently close; so that it would require , full moons to give the same amount of light as that of the sun. [ ] schroter, however, came to the conclusion that the moon has an atmosphere. [ ] a chart of the moon's surface, with the names of the principal physical features, will be found in ball's _story of the heavens_, nd edit., p. . it must be remembered that the moon as seen through a telescope appears in reversed position. [ ] _ibid._, p. . [ ] as represented by nasmyth's models in plaster. [ ] ball, _loc. cit._, p. . [ ] ball, _loc. cit._, p. . [ ] _astronomy_, p. . [ ] _outlines of astronomy_, p. . [ ] at rare intervals a few crescent-shaped ridges are discernible on the lunar sphere, but it is very doubtful if they are to be regarded as breached craters. [ ] the number of "spots" on the moon was considered to be until schroter increased it to , , and accurately described many of them. schroter seems to have been the earliest observer who identified the circular hollows on the moon's surface as volcanic craters. [ ] drawings of these very curious forms are given by judd, _volcanoes_, p. . chapter iii. are we living in an epoch of special volcanic activity? the question which we are about to discuss in the concluding chapter of this volume is one to which we ought to be able to offer a definite answer. this can only be arrived at by a comparison of the violence and extent of volcanic and seismic phenomena within the period of history with those of pre-historic periods. at first sight we might be disposed to give to the question an affirmative reply when we remember the eruptions of the last few years, and add to these the volcanic outbursts and earthquake shocks which history records. the cases of the earthquake and eruption in japan of november, , where in one province alone two thousand people lost their lives and many thousand houses were levelled[ ]; that of krakatoa, in ; of vesuvius, in ; and many others of recent date which might be named, added to those which history records;--the recollection of such cases might lead us to conclude that our epoch is one in which the subterranean volcanic forces had broken out with extraordinary energy over the earth's surface. still, when we come to examine into the cases of recorded eruptions--especially those of great violence--we find that they are limited to very special districts; and even if we extend our retrospect into the later centuries of our era, we shall find that the exceptionally great eruptions have been confined to certain permanently volcanic regions, such as the chain of the andes, that of the aleutian, kurile, japanese, and philippine and sunda islands, lying for the most part along the remarkable volcanic girdle of the world to which i have referred in a previous page. add to these the cases of iceland and the volcanic islands of the pacific, and we have almost the whole of the very active volcanoes of the world. then for the purposes of our inquiry we have to ascertain how these active vents of eruption compare, as regards the magnitude of their operations, with those of the pre-historic and later tertiary times. but before entering into this question it maybe observed, in the first place, that a large number of the vents of eruption, even along the chain of the earth's volcanic girdle, are dormant or extinct. this observation applies to many of the great cones and domes of the andes, including chimborazo and other colossal mountains in ecuador, columbia, chili, peru, and mexico. the region between the eastern rocky mountains and the western coast of north america was, as we have seen, one over which volcanic eruptions took place on a vast scale in later tertiary times; but one in which only the after-effects of volcanic action are at present in operation. we have also seen that the chain of volcanoes of japan and of the kurile islands are only active to a slight extent as compared with former times, and the same observation applies to those of new zealand. out of volcanoes in the japanese islands, only are now believed to be active. again, if we turn to other districts we have been considering, we find that in the indian peninsula, in arabia, in syria and the holy land, in persia, in abyssinia and asia minor--regions where volcanic operations were exhibited on a grand scale throughout the tertiary period, and in some cases almost down into recent times--we are met by similar evidences either of decaying volcanic energy, or of an energy which, as far as surface phenomena are concerned, is a thing of the past. lastly, turning our attention to the european area, notwithstanding the still active condition of etna, vesuvius, and a few adjoining islands, we see in all directions throughout southern italy evidences of volcanic operations of a past time,--such as extinct crater-cones, lakes occupying the craters of former volcanoes, and extensive deposits of tuff or streams of lava--all concurring in giving evidence of a period now past, when vulcanicity was widespread over regions where its presence is now never felt except when some earthquake shock, like that of the riviera, brings home to our minds the fact that the motive force is still beneath our feet, though under restrained conditions as compared with a former period. similar conclusions are applicable with even greater force to other parts of the european area. the region of the lower rhine and moselle, of hungary and the carpathians, of central france, of the north of ireland and the inner hebrides, all afford evidence of volcanic operations at a former period on an extensive scale; and the contrast between the present physically silent and peaceful condition of these regions, as regards any outward manifestations of sub-terrestrial forces, compared with those which were formerly prevalent, cannot fail to impress our minds irresistibly with the idea that volcanic energy has well-nigh exhausted itself over these tracts of the earth's surface. from this general survey of the present condition of the earth's surface, as regards the volcanic operations going on over it, and a comparison with those of a preceding period, we are driven to the conclusion that, however violent and often disastrous are the volcanic and seismic phenomena of the present day, they are restricted to comparatively narrow limits; and that even within these limits the volcanic forces are less powerful than they were in pre-historic times. the middle part of the tertiary period appears, in fact, to have been one of extraordinary volcanic activity, whether we regard the wide area over which this activity manifested itself, or the results as shown by the great amount of the erupted materials. many of the still active volcanic chains, or groups, probably had their first beginnings at the period referred to; but in the majority of cases the eruptive forces have become dormant or extinct. with the exception of the lavas of the indian-peninsular area, which appear, at least partially, to belong to the close of the cretaceous epoch, the specially volcanic period may be considered to extend from the beginning of the miocene down to the close of the pliocene stage. during the eocene stage, volcanic energy appears to have been to a great degree dormant; but plutonic energy was gathering strength for the great effort of the miocene epoch, when the volcanic forces broke out with extraordinary violence over europe, the british isles, and other regions, and continued to develop throughout the succeeding pliocene epoch, until the whole globe was surrounded by a girdle of fire. * * * * * the reply, therefore, to the question with which we set out is very plain; and is to the effect that the present epoch is one of comparatively low volcanic activity. the further question suggests itself, whether the volcanic phenomena of the middle tertiary period bear any comparison with those of past geological times. this, though a question of great interest, is one which is far too large to be discussed here; and it is doubtful if we have materials available upon which to base a conclusion. but it may be stated with some confidence, in general terms, that the history of the earth appears to show that, throughout all geological time, our world has been the theatre of intermittent geological activity, periods of rest succeeding those of action; and if we are to draw a conclusion regarding the present and future, it would be that, owing to the lower rate of secular cooling of the crust, volcanic action ought to become less powerful as the world grows older. [ ] admirably illustrated in prof. j. milne's recently published work, _the great earthquake of japan, _. appendix. a brief account of the principal varieties of volcanic rocks. the text-books on this subject are so numerous and accessible, that a very brief account of the volcanic rocks is all that need be given here for the purposes of reference by readers not familiar with petrological details. let it be observed, in the first place, that there is no hard and fast line between the varieties of igneous and volcanic rocks. in this as in other parts of creation--_natura nil facit per saltum_; there are gradations from one variety to the other. at the same time a systematic arrangement is not only desirable, but necessary; and the most important basis of arrangement is that founded on the proportion of _silica_ (or quartz) in the various rocks, as first demonstrated by durocher and bunsen, who showed that silica plays the same part in the inorganic kingdom that carbon does in the organic. upon this hypothesis, which is a very useful one to work with, these authors separated all igneous and volcanic rocks into two classes, viz., the basic and the acid; the former containing from - per cent., the latter - per cent. of that mineral. but there are a few intermediate varieties which serve to bridge over the space between the basic and acid groups. the following is a generalised arrangement of the most important rocks under the above heads:-- _tabular view of chief igneous and volcanic rocks._ basic group. . basalt and dolerite. . gabbro. . diorite. . diabase and melaphyre. . porphyrite. intermediate group. . syenite. . mica-trap, or lampophyre. . andesite. acid group. . trachyte, domite, and phonolite. . rhyolite and obsidian. . granophyre. . granite. in the above grouping, and in the following definitions, i have not been able to follow any special authority. but the most serviceable text-books are those of mr. frank rutley, _study of rocks_, and dr. hatch, _petrology_; also h. rosenbusch, _mikroskopische physiographie der mineralien_, and f. zirkel's _untersuchungen über mikroskopische structur der basaltgesteine_. we shall consider these in the order above indicated:-- . basalt.--the most extensively distributed of all volcanic rocks. it is a dense, dark rock of high specific gravity ( . - . ), consisting of plagioclase felspar (labradorite or anorthite), augite, and titano-ferrite (titaniferous magnetite). olivine is often present; and when abundant the rock is called "olivine-basalt." in the older rocks, basalt has often undergone decomposition into melaphyre; and amongst the metamorphic rocks it has been changed into diorite or hornblende rock; the augite having been converted into hornblende. when leucite or nepheline replaces plagioclase, the rock becomes a leucite-basalt,[ ] or nepheline-basalt. some basalts have a glass paste, or "ground-mass," in which the minerals are enclosed. the lava of vesuvius may be regarded as a variety of basalt in which leucite replaces plagioclase, although this latter mineral is also present. zirkel calls it "sanidin-leucitgestein," as both the macroscopic and microscopic structure reveal the presence of leucite, sanidine, plagioclase, nephiline, augite, mica, olivine, apatite, and magnetite.[ ] _dolerite_ does not differ essentially from basalt in composition or structure, but is a largely crystalline-granular variety, occurring more abundantly than basalt amongst the more ancient rocks, and the different minerals are distinctly visible to the naked eye. a remarkable variety of this rock occurs at slieve gullion in ireland, in which mica is so abundant as to constitute the rock a "micaceous dolerite." . gabbro.--a rather wide group of volcanic rocks with variable composition. essentially it is a crystalline-granular compound of plagioclase, generally labradorite and diallage. sometimes the pyroxenic mineral becomes hypersthene, giving rise to _hypersthene-gabbro_; or when hornblende is present, to _hornblende-gabbro_; when olivine, to _olivine-gabbro_. magnetite is always present. these rocks occur in the carlingford district in ireland, in the lizard district of cornwall, the inner hebrides (mull, skye, etc.) of scotland, and in saxony. . diorite.--a crystalline-granular compound of plagioclase and hornblende with magnetite. when quartz is present it becomes (according to the usual british acceptation) a _syenite_; but this view is gradually giving place to the german definition of syenite, which is a compound of orthoclase and hornblende; and it may be better to denominate the variety as _quartz-diorite_. the diorites are abundant as sheets and dykes amongst the older palæozoic and metamorphic rocks, and are sometimes exceedingly rich in magnetite. mica, epidote, and chlorite are also present as accessories. the rock occurs in north wales, charnwood forest, wicklow, galway, and donegal, and the highlands of scotland. there can be little doubt that amongst the metamorphic rocks of galway, mayo, and donegal the great beds of (often columnar) diorite were originally augitic lavas, which have since undergone transformation. . diabase.--it is very doubtful if "diabase" ought to be regarded as a distinct species of igneous rock, as it seems to be simply an altered variety of basalt or dolerite, in which chlorite, a secondary alteration-product, has been developed by the decomposition of the pyroxene or olivine of the original rock. it is a convenient name for use in the field when doubt occurs as to the real nature of an igneous rock. melaphyre is a name given to the very dark varieties of altered augitic lavas, rich in magnetite and chlorite. . porphyrite (or quartzless porphyry).--a basic variety of felstone-porphyry, consisting of a felspathic base with distinct crystals of felspar, with which there may be others of hornblende, mica, or augite. the colour is generally red or purple, and it weathers into red clay, in contrast to the highly acid or silicated felsites which weather into whitish sand. . syenite.--as stated above, this name has been variously applied. its derivation is from syene (assouan) in egypt, and the granitic rocks of that district were called "syenites," under the supposition (now known to be erroneous) that they differ from ordinary granites in that they were supposed to be composed of quartz, felspar, and hornblende, instead of quartz, felspar, and mica. from this it arose that syenite was regarded as a variety of granite in which the mica is replaced by hornblende, and this has generally been the british view of the question. but the german definition is applied to an entirely different rock, belonging to the felstone family; and according to this classification syenite consists of a crystalline-granular compound of orthoclase and hornblende, in which quartz may or may not be present. from this it will be seen that, according to zirkel, syenite is essentially distinct from diorite in the species of its felspar.[ ] it seems desirable to adopt the german view; and as regards diorites containing quartz as an accessory, to apply to them the name of _quartz-diorite_, as stated above, the name syenite as used by british geologists having arisen from a misconception. . mica-trap (lampophyre).--a rock, allied to the felstone family, in which mica is an abundant and essential constituent, thus consisting of plagioclase and mica, with a little magnetite. quartz may be an accessory. this rock occurs amongst the lower silurian strata of ireland, cumberland, and the south of scotland; it is not volcanic in the ordinary acceptation of that term. the term _lampophyre_ was introduced by gümbel in describing the mica-traps of fichtelgebirge. . andesite.--this is a dark-coloured, compact or vesicular, semi-vitreous group of volcanic rocks, composed essentially of a glassy plagioclase felspar, and a ferro-magnesian constituent enclosed in a glassy base. according to the nature of the ferro-magnesian constituent, the group may be divided into _hornblende-andesite_, _biotite-andesite_, and _augite-andesite_. quartz is sometimes present, and when this mineral becomes an essential it gives rise to a variety called _quartz-andesite_ or _dacite_. these rocks are the principal constituents of the lavas of the andes, and the name was first applied to them by leopold von buch; but their representatives also occur in the british isles, germany, and elsewhere. dacite is the lava of krakatoa and some of the volcanoes of japan. , . trachyte and domite, etc.--these names include very numerous varieties of highly silicated volcanic rock, and in their general form consist of a white felsitic paste with distinct crystals of sanidine, together with plagioclase, augite, biotite, hornblende, and accessories. when crystalline grains or blebs of quartz occur, we have a quartz-trachyte; when tridymite is abundant, as in the trachyte of co. antrim, we have "tridymite-trachyte." the trachytes occupy a position between the pitchstone lavas on the one hand, and the andesites and granophyres on the other. (_b._) _domite_ is the name applied to the trachytic rocks of the auvergne district and the puy de dôme particularly. they do not contain free quartz, though they are highly acid rocks, containing sometimes as much as per cent. of silica. (_c._) _phonolite (clinkstone)_ is a trachytic rock, composed essentially of sanidine, nepheline, and augite or hornblende. it is usually of a greenish colour, hard and compact, so as to ring under the hammer; hence the name. the wolf rock is composed of phonolite, and it occurs largely in auvergne. (_d._) _rhyolites_ are closely connected with the _quartz-trachytes_, but present a marked fluidal, spherulitic, or perlitic structure. they consist of a trachytic ground-mass in which grains or crystals of quartz and sanidine, with other accessory minerals, are imbedded. they occur amongst the volcanic rocks of the british isles, hungary, and the lipari islands, from which the name _liparite_ has been derived. (_e._) _obsidian (pitchstone)._--this is a vitreous, highly acid rock, which has become a volcanic glass in consequence of rapid cooling, distinct minerals not having had time to form. it has a conchoidal fracture, various shades of colour from grey to black; and under the microscope is seen to contain crystallites or microliths, often beautifully arranged in stellate or feathery groups. spherulitic structure is not infrequent; and occasionally a few crystals of sanidine, augite, or hornblende are to be seen imbedded in the glassy ground-mass. the rock occurs in dykes and veins in the western isles of scotland, in antrim, and on the borders of the mourne mountains, near newry, in ireland. . granophyre.--this term, according to geikie, embraces the greater portion of the acid volcanic rocks of the inner hebrides. they are closely allied to the quartz-porphyries, and vary in texture from a fine felsitic or crystalline-granular quartz-porphyry, in the ground-mass of which porphyritic turbid felspar and quartz may generally be detected, to a granitoid rock of medium grain, in which the component dull felspar and clear quartz can be readily distinguished by the naked eye. throughout all the varieties of texture there is a strong tendency to the development of minute irregularly-shaped cavities, inside of which quartz or felspar has crystallised out--a feature characteristic of the granites of arran and of the mourne mountains. . granite.--a true granite consists of a crystalline-granular rock consisting of quartz, felspar (orthoclase), and mica; the quartz is the paste or ground-mass in which the felspar and mica crystals are enclosed. this is the essential distinction between a granite and a quartz-porphyry or a granophyre. owing to the presence of highly-heated steam under pressure in the body of the mass when in a molten condition, the quartz has been the last of the minerals to crystallise out, and hence does not itself occur with the crystalline form. true granite is not a volcanic rock, and its representatives amongst volcanic ejecta are to be found in the granophyres, quartz-porphyries, felsites, trachytes, and rhyolites so abundant in most volcanic countries, and to one or other of these the so-called granites of the mourne mountains, of arran island, and of skye are to be referred. granite is a rock which has been intruded in a molten condition amongst the deep-seated parts of the crust, and has consolidated under great pressure in presence of aqueous vapour and with extreme slowness, resulting in the formation of a rock which is largely crystalline-granular. its presence at the surface is due to denudation of the masses by which it was originally overspread. [illustration: plate i.] explanation of plate i. magnified sections of vesuvian minerals. fig. . section of leucite crystal from the lava of , with fluid cavities. mag., diams. " , , , and . sections of nepheline crystals from the lava of , , and . " . section of sodalite crystal from the lava of , with belonites and crystals of magnetite enclosed. " , , . crystals of leucite with microliths and cavities darkened by magnetite dust; also, containing crystals of magnetite. " . group of leucite crystals of irregular form from the lava of , congregated around a nucleus of crystals of plagioclase and magnetite. [illustration: plate ii.] explanation of plate ii. magnified sections of vesuvian minerals. fig. . section of augite crystal from the lava of , with numerous gas cells and delicately banded walls. the interior contains two long prisms, probably of apatite. " . crystal of augite with banded walls, and indented by leucite crystals, from the lava of . mag., diams. " , , . sections of augite crystals from the lavas of and . " . group of augite crystals from the lava of . " . ditto from the lava of , with encluded mica-flake (_a_) and portion of the glass paste, or ground-mass, of the rock (_b_), containing microliths and grains of magnetite. fig. . two crystals of olivine from the lava of ; they are intersected on one side by the plane of the thin section, and are remarkable for showing lines of gas cells, and bands of growth sometimes cellular. mag., diams. " . section of rock-crystal (quartz), with double terminal pyramids, from the lava of . " . twin crystal of sanidine from the lava of . mag., diams. " , , . sections of plagioclase crystals (probably labradorite) from the lava of . mag., diams. " . section of olivine crystal from the lava of --imperfectly formed. mag., diams. " . section of mica-flake from the lava of . mag., diams. [illustration: plate iii.] explanation of plate iii. magnified sections of volcanic rocks. . diorite dyke, traversing assynt limestone, north highlands. . basalt from upper beds, near giant's causeway, county antrim. . hornblende-hypersthene-augite andesite, from pichupichu, andes. . augite-andesite from pichupichu, andes. . olivine dolerite, with hornblende and biotite, madagascar. . leucite basalt, with mellilite, capo di bove, italy. [illustration: plate iv.] explanation of plate iv. magnified sections of volcanic rocks. . vesuvian lava, glass paste with numerous crystals of leucite; others of augite and nepheline porphyritically developed; also small grains of magnetite. . vesuvian lava, glass paste with numerous crystals of leucite; others of olivine, hornblende, and sanidine, porphyritically developed; small grains of magnetite. . trachyte from hungary; felsitic paste with crystals of hornblende and sanidine, and a little magnetite. . gabbro, from carlingford hill, ireland, consisting of anorthite, augite, a little olivine, and magnetite. . dolerite, from old volcanic neck, scalot hill, near lame, consisting of labradorite, augite, olivine, and magnetite. . dolerite, ballintoy, county antrim, showing ophetic structure, consisting of augite, labradorite, and magnetite. [ ] mr. s. allport has discovered this in the rock called the "wolf rock" off the coast of cornwall. the most important work on basalt is that by f. zirkel, _unters. über mikros. zusammensetzung und structur der basaltgesteine_. bonn ( ). [ ] zirkel, _die mikroskopische beschaffenheit der mineralien und gesteine_, p. . leipsig ( ). [ ] zirkel, _petrog._, i. ; b. von cotta, p. (eng. trans.). index. index. abyssinian table-lands, _et seq._ albano, lake, america, volcanic regions of north, _et seq._; of western, andes, , , , andesite, antrim, _et seq._ arabia, dormant volcanoes of, - arabian desert, archibald, c. d., arizona, volcanoes of, argyll, duke of, ascension, ashangi, volcanic series of, atmospheric effects of krakatoa eruption, - auckland district, volcanoes of, auvergne, volcanic regions of, , , _et seq._ azores, ball, sir r. s., , basalt, blanford, w. t., , bonneville, lake, - british isles, tertiary volcanic districts of, _et seq._, ; pre-tertiary volcanic districts of, _et seq._ buch, l. von, , , california, volcanoes of, callirrhoë, springs of, cañon, the grand, cantal, volcanoes of the, - cape colony, basalts of, charleston earthquake, , , chambers, g. f., charnwood forest, chimborazo, clermont, vale of, - clinkstone, cordilleras of quito, cotopaxi, - , , crater-cones, lava, crateriform cones, craterless domes, dana, prof. j. d., , , darwin, , darwin, prof. g. h., , daubeny, , , davison, c., , davy, sir h., deccan trap-series, _et seq._ demavend, mount, diabase, diorite, dolerite, domite, dore, volcanoes of mont, - doughty, c. m., durocher, dutton, capt. c. e., , , dykes in ireland, - earthquakes, _et seq._ errigal, etna, , _et seq._, fingal's cave, forbes, d., france, extinct volcanoes of, _et seq._ gabbro, gardner, j. s., geikie, sir a., , , , , , , , , , giant's causeway, - granite, granophyre, ; of mull, green, prof. a. h., hatch, dr., haughton, prof., haurân, volcanoes of the, , haute loire, volcanic districts of, - hawaii, volcanoes of, , , hecla, herschel, sir j., hibbert, dr. s., , , hochstetter, f. von, hopkins, , hull, dr. e. g., humboldt, a. von, , hutton, james, iceland, volcanoes of, - ireland, volcanic tertiary rocks of, _et seq._ jaulân, johnston-lavis, jordan valley, _et seq._, jorullo, judd, prof., , , , , , , krakatoa, eruption of, _et seq._ kurile islands, volcanoes of, laacher see, - lampophyre, lancerote, lasaulx, prof. von, lavas, relative density of, - lima in , earthquake of, lipari islands, volcanoes of, _et seq._ lisbon, earthquake of, lister, j. j., lunar volcanoes, _et seq._ lyell, sir c., , , , mackowen, col., magdala, volcanic series of, - mallet, r., , mauna loa, , , mica-trap, milne, prof., , , moab, volcanic regions of, moon, volcanoes of, _et seq._ monte nuovo, mull, _et seq._ neapolitan group of volcanoes, new zealand, volcanoes of, obsidian, ocean waves of seismic origin, , o'reilly, prof., , orizaba, ovid, pacific, volcanic islands of, palestine, dormant volcanoes of, - palmieri, prof., pantelleria, phlegræan fields, phonolite, pitchstone, pliny, , porphyrite, powell, major, pre-tertiary volcanic rocks, _et seq._; of british isles, _et seq._ puy de dôme, - pythagoreans on volcanoes, - quito, cordilleras of, rangitoto, , reyer, dr. e., rhine valley, volcanoes of, _et seq._ rhyolite, riviera in , earthquake of, rocca monfina, roderberg, , rome, - rosenbusch, h., roto mahana, ruapahu, russell, hon. rollo, rutley, f., st. helena, san francisco, mount, santorin, - schehallion, schumacher, scotland, volcanic districts of, _et seq._ scrope, poulett, , , , scuir of eigg, - seismic phenomena, special, _et seq._, _et seq._ shasta, mount, siebengebirge, - skye, - sleamish, smyth, piazzi, snake river, volcanoes of, staffa, - strabo on volcanoes, stromboli, - sumatra, volcanic action in, syenite, symes, r. g., syria, earthquakes in, taupo lake, taylor, mount, tell el ahmâr, tell el akkasheh, tell el farras, tell abû en nedâ, tell abû nedîr, templepatrick, quarry at, teneriffe, tertiary period, volcanic activity of, thucydides, tonga islands, volcanoes of, tongariro, trachyte, trass of brühl valley, - tristan da cunha, tristram, canon, , utah, volcanoes of, verbeek, r. d. m., vesuvius, , , - , , volcanoes, historic notices of, - ; form, structure, and composition of, - ; lines and groups of active, - ; of mid-ocean, - ; extinct or dormant, _et seq._; special volcanic and seismic phenomena, _et seq._; the ultimate cause of volcanic action, _et seq._; whether we are living in an epoch of special volcanic activity, - ; brief account of volcanic rocks, - vulcanists, vulcano, , wallace, a. r., waltershausen, w. s. von, , wellington, mount, wharton, capt., whymper, e., yarmûk, valley of the, , yellowstone park, zirkel, f., zöllner, the walter scott press, newcastle-on-tyne. the contemporary science series. edited by havelock ellis. * * * * * crown vo, cloth, s. d. per vol.; half morocco, s. d. i. the evolution of sex. by professor patrick geddes and j. arthur thomson. with illustrations. second edition. 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"mr. hartland's book will win the sympathy of all earnest students, both by the knowledge it displays, and by a thorough love and appreciation of his subject, which is evident throughout."--_spectator._ xii. primitive folk. by elie reclus. "for an introduction to the study of the questions of property, marriage, government, religion,--in a word, to the evolution of society,--this little volume will be found most convenient."--_scottish leader._ xiii. the evolution of marriage. by professor letourneau. "among the distinguished french students of sociology, professor letourneau has long stood in the first rank. he approaches the great study of man free from bias and shy of generalisations. to collect, scrutinise, and appraise facts is his chief business."--_science._ xiv. bacteria and their products. by dr. g. sims woodhead. illustrated. "an excellent summary of the present state of knowledge of the subject."--_lancet._ xv. education and heredity. by j. m. guyau. "it is a sign of the value of this book that the natural impulse on arriving at its last page is to turn again to the first, and try to gather up and coordinate some of the many admirable truths it presents."--_anti-jacobin._ xvi. the man of genius. by professor lombroso. illustrated. "by far the most comprehensive and fascinating collection of facts and generalisations concerning genius which has yet been brought together."--_journal of mental science._ xvii. the grammar of science. by professor karl pearson. illustrated. xviii. property: its origin and development. by ch. letourneau, general secretary to the anthropological society, paris, and professor in the school of anthropology, paris. an ethnological account of the beginnings of property among animals, of its communistic stages among primitive races, and of its later individualistic developments, together with a brief sketch of its probable evolution in the future. * * * * * london: walter scott, limited, warwick lane. * * * * * transcriber's note: changed 'kilarrea' to 'kilauea' on page : mauna loa and kilarrea. changed 'kilanea' to 'kilauea' on page : kilanea, feet. made punctuation (semi-colons) consistent in caption to figure . changed 'brionde' to 'brioude' on page : till at brionde it becomes. changed 'occuping' to 'occupying' on page : occuping a hollow. changed 'rodesberg' to 'roderberg' on page : old extinct volcano of rodesberg. changed 'wolkenberg' to 'wolkenburg' on page : and that of the wolkenberg. left the reference to jeremiah, l. . in footnote to part iii chapter i, although jeremiah, li. . seems more appropriate. changed 'fumarols' to 'fumaroles' on page : fumarols give evidence. removed extra comma on page : of the present, epoch. changed 'columnal' to 'columnar' on page : the columnal structure. changed 'groves' to 'grooves' on page : the groves and scorings. changed 'angust' to 'august' on page : the th of angust. changed 'mikroskopischen' to 'mikroskopische' on page : über mikroskopischen structur. changed 'become' to 'becomes' on page : the rock become a leucite-basalt. left inconsistent spellings of 'baalbec' and 'baalbeck'; 'harrat' and 'harrât'; 'mètres' and 'metres'; 'pitchstone' and 'pitch-stone'; 'prehistoric' and 'pre-historic'; 'rhône' and 'rhone'; 'sub-aerial', 'subaërial' and 'subaerial'; 'tableland' and 'table-land'. greek words were replaced with their transliterations: 'meson pyr' and 'peri kosmou'. the oe-ligature was expanded to the two separate characters: 'euboea' and 'boeotia'. left the list numbering as is at the beginning of chapter ii of part iv, even though the list begins at item c, as if it continues the list which began in the previous chapter. note: project gutenberg also has an html version of this file which includes the original illustrations. see -h.htm or -h.zip: (http://www.gutenberg.net/dirs/ / / / / / -h/ -h.htm) or (http://www.gutenberg.net/dirs/ / / / / / -h.zip) +--------------------------------------------------------------+ | transcriber's note: | | | | inconsistent hyphenation in the original document has been | | preserved. there are many unusual words in this document! | | | | a number of obvious typographical errors have been corrected | | in this text. for a complete list, please see the end of | | this document. | | | +--------------------------------------------------------------+ dinosaurs with special reference to the american museum collections by w. d. matthew curator of vertebrate palæontology ... '_dragons of the prime that tare each other in their slime_' [illustration: skull of the great carnivorous dinosaur tyrannosaurus in the american museum.] new york american museum of natural history dinosaurs. table of contents. chapter i. the age of reptiles. its antiquity, duration and significance in geological history. chapter ii. north america in the age of reptiles. its geographic and climatic changes. chapter iii. kinds of dinosaurs. common characters and differences between the various groups. classification. chapter iv. the carnivorous dinosaurs--allosaurus, tyrannosaurus, ornitholestes, etc. chapter v. the amphibious dinosaurs--brontosaurus, diplodocus, etc. chapter vi. the beaked dinosaurs. the iguanodonts--iguanodon, camptosaurus. chapter vii. the beaked dinosaurs (continued). the duckbilled dinosaurs--trachodon, saurolophus. chapter viii. the beaked dinosaurs (continued). the armored dinosaurs--stegosaurus, ankylosaurus. chapter ix. the beaked dinosaurs (concluded). the horned dinosaurs--triceratops, etc. chapter x. geographical distribution of dinosaurs. chapter xi. collecting dinosaurs. how and where they are found. the first discovery of dinosaurs in the west. the bone-cabin quarry. fossil hunting by boat in canada. preface. this volume is in large part a reprint of various popular descriptions and notices in the american museum journal and elsewhere by professor henry fairfield osborn, mr. barnum brown, and the writer. there has been a considerable demand for these articles which are now mostly out of print. in reprinting it seemed best to combine and supplement them so as to make a consecutive and intelligible account of the dinosaur collections in the museum. the original notices are quoted verbatim; for the remainder of the text the present writer is responsible. professor s.w. williston of chicago university has kindly contributed a chapter--all too brief--describing the first discoveries of dinosaurs in the western formations that have since yielded so large a harvest. the photographs of american museum specimens are by mr. a.e. anderson; the field photographs by various museum expeditions; the restorations by mr. charles r. knight. most of these illustrations have been published elsewhere by professor osborn, mr. brown and others. the diagrams, figs. - , , , and , are my own. w. d. m. chapter i. the age of reptiles. its antiquity, duration and significance in geologic history. palæontology deals with the history of life. its time is measured in geologic epochs and periods, in millions of years instead of centuries. man, by this measure, is but a creature of yesterday--his "forty centuries of civilization"[ ] but a passing episode. it is by no means easy for us to adjust our perspective to the immensely long spaces of time involved in geological evolution. we are apt to think of all these extinct animals merely as prehistoric--to imagine them all living at the same time and contending with our cave-dwelling ancestors for the mastery of the earth. in order to understand the place of the dinosaurs in world-history, we must first get some idea of the length of geologic periods and the immense space of time separating one extinct fauna from another. _the age of man._ prehistoric time, as it is commonly understood, is the time when barbaric and savage tribes of men inhabited the world but before civilization began, and earlier than the written records on which history is based. this corresponds roughly to the pleistocene epoch of geology; it is included along with the much shorter time during which civilization has existed, in the latest and shortest of the geological periods, the quaternary. it was the age of the mammoth and the mastodon, the megatherium and irish deer and of other quadrupeds large and small which are now extinct; but most of its animals were the same species as now exist. it was marked by the great episode of the ice age, when considerable parts of the earth's surface were buried under immense accumulations of ice, remnants of which are still with us in the icy covering of greenland and antarctica. _the age of mammals._ before this period was a very much longer one--at least thirty times as long--during which modern quadrupeds were slowly evolving from small and primitive ancestors into their present variety of form and size. this is the tertiary period or age of mammals. through this long period we can trace step by step the successive stages through which the ancestors of horses, camels, elephants, rhinoceroses, etc., were gradually converted into their present form in adaptation to their various habits and environment. and with them were slowly evolved various kinds of quadrupeds whose descendants do not now exist, the titanotheres, elotheres, oreodonts, etc., extinct races which have not survived to our time. man, as such, had not yet come into existence, nor are we able to trace any direct and complete line of ancestry among the fossil species known to us; but his collateral ancestors were represented by the fossil species of monkeys and lemurs of the tertiary period. [illustration: fig. .--the later ages of geologic time.] _the age of reptiles._ preceding the age of mammals lies a long vista of geologic periods of which the later ones are marked by the dominance of reptiles, and are grouped together as the age of reptiles or mesozoic era. this was the reign of the dinosaurs, and in it we are introduced to a world of life so different from that of today that we might well imagine ourselves upon another planet. none of the ordinary quadrupeds with which we are familiar then existed, nor any related to nor resembling them. but in their place were reptiles large and small, carnivorous and herbivorous, walking, swimming and even flying. _crocodiles, turtles and sea reptiles._ the crocodiles and turtles of the swamps were not so very different from their modern descendants; there were also sea-crocodiles, sea-turtles, huge marine lizards (mosasaurs) with flippers instead of feet; and another group of great marine reptiles (plesiosaurs) somewhat like sea-turtles but with long neck and toothed jaws and without any carapace. these various kinds of sea-reptiles took the place of the great sea mammals of modern times (which were evolved during the age of mammals); of whales and dolphins, seals and walruses, and manatees. _pterodactyls._ the flying reptiles or pterosaurians, partly took the place of birds, and most of them were of small size. strange bat-winged creatures, the wing membrane stretched on the enormously elongated fourth finger, they are of all extinct reptiles the least understood, the most difficult to reconstruct and visualize as they were in life. _dinosaurs._ the land reptiles were chiefly dinosaurs, a group which flourished throughout the age of reptiles and became extinct at its close. "dinosaur" is a general term which covers as wide a variety in size and appearance as "quadruped" among modern animals. and the dinosaurs in the age of reptiles occupied about the same place in nature as the larger quadrupeds do today. they have been called the giant reptiles, for those we know most about were gigantic in size, but there were also numerous smaller kinds, the smallest no larger than a cat. all of them had short, compact bodies, long tails, and long legs for a reptile, and instead of crawling, they walked or ran, sometimes upon all fours, more generally upon the hind limbs, like ostriches, the long tail balancing the weight of the body. some modern lizards run this way on occasion, especially if they are in a hurry. but the bodies of lizards are too long and their limbs too small and slender for this to be the usual mode of progress, as it seems to have been among the dinosaurs. animals of the age of reptiles. land reptiles. dinosaurs corresponding to the larger quadrupeds or land mammals of today. crocodiles, lizards and turtles still surviving. sea reptiles. plesiosaurs } corresponding to whales, dolphins, seals, ichthyosaurs } etc., or sea-mammals of today. mosasaurs } flying reptiles or pterosaurs. birds with teeth (scarce and little known). primitive mammals of minute size (scarce and little known). fishes and invertebrates many of them of extinct races, all more or less different from modern kinds. fishes, large and small, were common in the seas and rivers of the age of reptiles but all of them were more or less different from modern kinds, and many belonged to ancient races now rare or extinct. the lower animals or invertebrates were also different from those of today, although some would not be very noticeably so at first glance. among molluscs, the ammonites, related to the modern pearly nautilus, are an example of a race very numerous and varied during all the periods of the reptilian era, but disappearing at its close, leaving only a few collateral descendants in the squids, cuttlefish and nautili of the modern seas. the brachiopods were another group of molluscs, or rather molluscoids for they were not true molluscs, less abundant even then than in previous ages and now surviving only in a few rare and little known types such as the lamp-shell (_terebratulina_). _insects._ the insect life of the earlier part of the age of reptiles was notable for the absence of all the higher groups and orders, especially those adapted to feed on flowers. there were no butterflies or moths, no bees or wasps or ants although there were plenty of dragonflies, cockroaches, bugs and beetles. but in the latter part of this era, all these higher orders appeared along with the flowering plants and trees. _plants._ the vegetation in the early part of the era was very different both from the gloomy forests of the more ancient coal era and from that which prevails today. cycads, ferns and fern-like plants, coniferous trees, especially related to the modern _araucaria_ or norfolk island pine, ginkgos still surviving in china, and huge equisetae or horsetail rushes, still surviving in south american swamps and with dwarfed relatives throughout the world, were the dominant plant types of that era. the flowering plants and deciduous trees had not appeared. but in the latter half of the era these appeared in ever increasing multitudes, displacing the lower types and relegating them to a subordinate position. unlike the more rapidly changing higher animals these ancient mesozoic groups of plants have not wholly disappeared, but still survive, mostly in tropical and southern regions or as a scanty remnant in contrast with their once varied and dominant role. there is every reason to believe that upon the appearance of these higher plants whose flower and fruit afforded a more concentrated and nourishing food, depended largely the evolution of the higher animal life both vertebrate and insect, of the cenozoic or modern era. footnotes: [footnote : the records of egypt and chaldaea extend back at least sixty centuries.] chapter ii. north america in the age of reptiles. its geographic and climatic changes. north america in the age of reptiles would have seemed almost as strange to our eyes in its geography as in its animals and plants. the present outlines of its coast, its mountains and valleys, its rivers and lakes, have mostly arisen since that time. even the more ancient parts of the continent have been profoundly modified through the incessant work of rain and rivers and of the waves, tending to wear down the land surfaces, of volcanic outbursts building them up, and of the more mysterious agencies which raise or depress vast stretches of mountain chains or even the whole area of a continent, and which tend on the whole so far as we can see, to restore or increase the relief of the continents, as the action of the surface waters tends to bring them down to or beneath the sea level. _alternate overflow and emergence of continents._ in a broad way these agencies of elevation and of erosion have caused in their age-long struggle an alternation of periods of overflow and periods of continental emergence during geologic time. during the periods of overflow, great portions of the low-lying parts of the continents were submerged, and formed extensive but comparatively shallow seas. the mountains through long continued erosion were reduced to gentle and uniform slopes of comparatively slight elevation. their materials were brought down by rivers to the sea-coast, and distributed as sedimentary formations over the shallow interior seas or along the margins of the continents. but this load of sediments, transferred from the dry land to the ocean margins and shallow seas, disturbed the balance of weight (isostasy) which normally keeps the continental platforms above the level of the ocean basins (which as shown by gravity measurement are underlain by materials of higher specific gravity than the continents). in due course of time, when the strain became sufficient, it was readjusted by earth movements of a slowness proportioned to their vastness. these movements while tending upon the whole to raise the continents to or sometimes beyond their former relief, did not reverse the action of erosion agencies in detail, but often produced new lines or areas of high elevation. [illustration: fig. .--north america in the later cretacic period. map outlines after schuchert.] _geologic periods._ a geologic period is the record of one of these immense and long continued movements of alternate submergence and elevation of the continents. it begins, therefore, and ends with a time of emergence, and includes a long era of submergence. these epochs of elevation are accompanied by the development of cold climates at the poles, and elsewhere of arid conditions in the interior of the continents. the epochs of submergence are accompanied by a warm, humid climate, more or less uniform from the equator to the poles. the earth has very recently, in a geologic sense, passed through an epoch of extreme continental elevation the maximum of which was marked by the "ice age." the continents are still emerged for the most part almost to the borders of the "continental shelf" which forms their maximum limit. and in the icy covering of greenland and antarctica a considerable portion still remains of the great ice-sheets which at their maximum covered large parts of north america and europe. we are now at the beginning of a long period of slow erosion and subsidence which, if this interpretation of the geologic record be correct, will in the course of time reduce the mountains to plains and submerge great parts of the lowlands beneath the ocean. as compensation for the lesser extent of dry land we may look forward to a more genial and favorable climate in the reduced areas that remain above water. [illustration: fig. .--relative length of ages of reptiles, mammals and man.] _length of geologic cycles._ but these vast cycles of geographic and climatic change will take millions of years to accomplish their course. the brief span of human life, or even the few centuries of recorded civilization are far too short to show any perceptible change in climate due to this cause. the utmost stretch of a man's life will cover perhaps one-two hundred thousandth part of a geologic period. the time elapsed since the dawn of civilization is less than a three-thousandth part. of the days and hours of this geologic year, our historic records cover but two or three minutes, our individual lives but a fraction of a second. we must not expect to find records of its changing seasons in human history, still less to observe them personally. [illustration: fig. .--relative length of prehistoric and historic time.] there are indeed minor cycles of climate within this great cycle. the great ice age through which the earth has so recently passed was marked by alternations of severity and mildness of climate, of advance and recession of the glaciers, and within these smaller cycles are minor alternations whose effect upon the course of human history has been shown recently by professor huntington ("the pulse of asia"). but the great cycles of the geologic periods are of a scope far too vast for their changes to be perceptible to us except through their influence upon the course of evolution. _the later cycles of geologic time._ the reptilian era opens with a period of extreme elevation, which rivalled that of the glacial epoch and was similarly accompanied by extensive glaciation of which some traces are preserved to our day in characteristic glacial boulders, ice scratches, and till, imbedded or inter-stratified in the strata of the permian age. between these two extremes of continental emergence, the permian and the pleistocene, we can trace six cycles of alternate submergence and elevation, as shown in the diagram (fig. ), representing the proportion of north america which is known to have been above water during the six geologic periods that intervene. from this diagram it will appear that the six cycles or periods were by no means equal in the amount of overflow or complete recovery of the drowned lands. the cretacic period was marked by a much more extensive and long continued flooding; the great plains west of the mississippi were mostly under water from the gulf of mexico to the arctic ocean. the earlier overflows were neither so extensive nor so long continued. the great uplift of the close of the cretacic regained permanently the great central region and united east and west, and the overflows of the age of mammals were mostly limited to the south atlantic and gulf coasts. _sedimentary formations._ during the epochs of greatest overflow great marine formations were deposited over large areas of what is now dry land. these were followed as the land rose to sea level by extensive marsh and delta formations, and these in turn by scattered and fragmentary dry land deposits spread by rivers over their flood plains. in the marine formations are found the fossil remains of the sea-animals of the period; in the coast and delta formations are the remains of those which inhabited the marshes and forests of the coast regions; while the animals of the dryland, of plains and upland, left their remains in the river-plain formations. [illustration: fig. .--geologic cycles and the land area of north america (after schuchert).] these last, however, fragmentary and loose and overlying the rest, were the first to be swept away by erosion during the periods of elevation; and of such formations in the age of reptiles very little, if anything, seems to have been preserved to our day. consequently we know very little about the upland animals of those times, if as seems very probable, they were more or less different from the animals of the coast-forests and swamps. the river-plain deposits of the age of mammals on the other hand, are still quite extensive, especially those of its later epochs, and afford a fairly complete record in some parts of the continent of the upland fauna of those regions. _occurrence of dinosaur bones._ dinosaur bones are found mostly in the great delta formations, and since those were accumulated chiefly in the early stages of great continental elevations, it follows that our acquaintance with dinosaurs is mostly limited to those living at certain epochs during the age of reptiles. in point of fact so far as explorations have yet gone in this country, the dinosaur fauna of the close of the jurassic and beginning of the comanchic and that of the later cretacic are the only ones we know much about. the immense interval of time that preceded, and the no less vast stretch of time that separated them, is represented in the record of dinosaur history by a multitude of tracks and a few imperfect skeletons assigned to the close of the triassic period, and by a few fragments from formations which may be intermediate in age between the jurassic-comanchic and the late cretacic. consequently we cannot expect to trace among the dinosaurs, the gradual evolution of different races, as we can do among the quadrupeds of the age of mammals. _imperfection of the geologic record._ the age of mammals in north america presents a moving picture of the successive stages in the evolution of modern quadrupeds; the age of reptiles shows (broadly considered) two photographs representing the land vertebrates of two long distant periods, as remote in time from each other as the later one is remote from the present day. of the earlier stages in the evolution of the dinosaurs there are but a few imperfect sketches in this country; in europe the picture is more complete. in the course of time, as exploration progresses, we shall no doubt recover more complete records. but probably we shall never have so complete a history of the terrestrial life of the age of reptiles as we have of the age of mammals. the records are defective, a large part of them destroyed or forever inaccessible. chapter iii. kinds of dinosaurs. common characters and differences between the various groups. in the preceding chapter we have attempted to point out the place in nature that the dinosaurs occupied and the conditions under which they lived. they were the dominant land animals of their time, just as the quadrupeds were during the age of mammals. their sway endured for a long era, estimated at nine millions of years, and about three times as long as the period which has elapsed since their disappearance. they survived vast changes in geography and climate, and became extinct through a combination of causes not fully understood as yet; probably the great changes in physical conditions at the end of the cretacic period, and the development of mammals and birds, more intelligent, more active, and better adapted to the new conditions of life, were the most important factors in their extinction. the dinosaurs originated, so far as we can judge, as lizard-like reptiles with comparatively long limbs, long tails, five toes on each foot, tipped with sharp claws, and with a complete series of sharp pointed teeth. it would seem probable that these ancestors were more or less bipedal, and adapted to live on dry land. they were probably much like the modern lizards in size, appearance and habitat:[ ] from this ancestral type the dinosaurs evolved into a great variety of different kinds, many of them of gigantic size, some herbivorous, some carnivorous; some bipedal, others quadrupedal; many of them protected by various kinds of bony armor-plates, or provided with horns or spines; some with sharp claws, others with blunted claws or hoofs. [illustration: fig. .--outline restorations of dinosaurs. scale about nineteen feet to the inch.] these various kinds of dinosaurs are customarily grouped as follows: i. _carnivorous dinosaurs_ or _theropoda_. with sharp pointed teeth, sharp claws; bipedal, with bird-like hind feet, generally three-toed;[ ] the fore-limbs adapted for grasping or tearing, but not for support of the body. the head is large, neck of moderate length, body unarmored. the principal dinosaurs of this group in america are _allosaurus_, _ornitholestes_--upper jurassic period. _tyrannosaurus, deinodon, albertosaurus, ornithomimus_--upper cretacic period. [illustration: fig. .--skulls of dinosaurs, illustrating the principal types--_anchisaurus_ after marsh, the others from american museum specimens.] ii. _amphibious dinosaurs_ or _sauropoda_. with blunt-pointed teeth and blunt claws, quadrupedal, with elephant-like limbs and feet, long neck and small head. unarmored. principal dinosaurs of this group in america are _brontosaurus_, _diplodocus_, _camarasaurus_ (_morosaurus_) and _brachiosaurus_, all of the upper jurassic and comanchic periods. iii. _beaked dinosaurs_ or _predentates_. with a horny beak on the front of the jaw, cutting or grinding teeth behind it. all herbivorous, with pelvis of peculiar type, with hoofs instead of claws, and many genera heavily armored. mostly three short toes on the hind foot, four or five on the fore foot. this group comprises animals of very different proportions as follows: . _iguanodonts._ bipedal, unarmored, with a single row of serrated cutting teeth, three-toed hind feet. upper jurassic, comanchic and cretacic. _camptosaurus_ is the best known american genus. . _trachodonts_ or _duck-billed dinosaurs_. like the iguanodonts but with numerous rows of small teeth set close together to form a grinding surface. cretacic period. _trachodon, hadrosaurus, claosaurus, saurolophus, corythosaurus, etc._ . _stegosaurs_ or _armored dinosaurs_. quadrupedal dinosaurs with elephantine feet, short neck, small head, body and tail armored with massive bony plates and often with large bony spines. teeth in a single row, like those of iguanodonts. _stegosaurus_ of the upper jurassic, _ankylosaurus_ of the upper cretacic. [illustration: fig. .--hind feet of dinosaurs, to show the three chief types (theropoda, orthopoda, sauropoda).] . _ceratopsian_ or _horned dinosaurs_. quadrupedal with elephantine feet, short neck, very large head enlarged by an enormous bony frill covering the neck, with a pair of horns over the eyes and a single horn in front. teeth in a single row, but broadened out and adapted for grinding the food. no body armor. _triceratops_ is the best known type. _monoclonius_, _ceratops_, _torosaurus_ and _anchiceratops_ are also of this group. all from the cretacic period. _classification of dinosaurs._ it is probable that the dinosaurs are not really a natural group or order of reptiles, although they have been generally so considered. the carnivorous and amphibious dinosaurs in spite of their diverse appearance and habits, are rather nearly related, while the beaked dinosaurs form a group apart, and may be descendants of a different group of primitive reptiles. these relations are most clearly seen in the construction of the pelvis (see fig. ). in the first two groups the pubis projects downward and forward as it does in the majority of reptiles, and the ilium is a high rounded plate; while in the others the pelvis is of a wholly different type, strongly suggesting the pelvis of birds. [illustration: fig. .--pelves of dinosaurs illustrating the two chief types (saurischia, ornithischia) and their variations.] recent researches upon triassic dinosaurs, especially by the distinguished german savants, friedrich von huene, otto jaekel and the late eberhard fraas, and the discovery of more complete specimens of these animals, also clear up the true relationships of these primitive dinosaurs which have mostly been referred hitherto to the theropoda or megalosaurians. the following classification is somewhat more conservative than the arrangement recently proposed by von huene. order saurischia seeley. suborder _coelurosauria_ von huene (=compsognatha huxley, symphypoda cope.) fam. podokesauridæ triassic, connecticut. " hallopodidæ jurassic, colorado. " coeluridæ jurassic and comanchic, north america. " compsognathidæ jurassic, europe. suborder _pachypodosauria_ von huene. fam. anchisauridæ triassic, north america and europe. " zanclodontidæ } " plateosauridæ } triassic, europe.* suborder _theropoda_ marsh (=goniopoda cope) fam. megalosauridæ jurassic and comanchic. " deinodontidæ cretacic. " ornithomimidæ cretacic, north america. suborder _sauropoda_ marsh (=opisthocoelia owen, cetiosauria seeley.) fam. cetiosauridæ } " morosauridæ } jurassic and comanchic. " diplodocidæ } order ornithischia seeley (=orthopoda cope, predentata marsh.) suborder _ornithopoda_ marsh (iguanodontia dollo) fam. nanosauridæ jurassic, colorado. " camptosauridæ } " iguanodontidæ } jurassic and comanchic. " trachodontidæ (=hadrosauridæ), cretacic. suborder _stegosauria_ marsh. fam. scelidosauridæ } jurassic and comanchic. " stegosauridæ } " ankylosauridæ (=nodosauridæ), cretacic. suborder _ceratopsia_ marsh. fam. ceratopsidæ cretacic. * regarded by dr. von huene as ancestral respectively to the theropoda and sauropoda. footnotes: [footnote : if some vast catastrophe should today blot out all the mammalian races including man, and the birds, but leave the lizards and other reptiles still surviving, with the lower animals and plants, we might well expect the lizards in the course of geologic periods to evolve into a great and varied land fauna like the dinosaurs of the mesozoic era.] [footnote : the ancestral types have four complete toes, but in the true theropoda the inner digit is reduced to a small incomplete remnant, its claw reversed and projecting at the back of the foot, as in birds.] chapter iv. the carnivorous dinosaurs, allosaurus, tyrannosaurus, ornitholestes, etc. sub-order theropoda. the sharp teeth, compressed and serrated like a palaeolithic spear point, and the powerful sharp-pointed curved claws on the feet, prove the carnivorous habits of these dinosaurs. the well-finished joints, dense texture of the hollow bones and strongly marked muscle-scars indicate that they were active and powerful beasts of prey. they range from small slender animals up to the gigantic _tyrannosaurus_ equalling the modern elephant in bulk. they were half lizard, half bird in proportions, combining the head, the short neck and small fore limbs and long snaky tail of the lizard with the short, compact body, long powerful hind limbs and three-toed feet of the bird. the skin was probably either naked or covered with horny scales as in lizards and snakes; at all events it was not armor-plated as in the crocodile.[ ] they walked or ran upon the hind legs; in many of them the fore limbs are quite unfitted for support of the body and must have been used solely in fighting or tearing their prey. [illustration: fig. .--hind limb of allosaurus, dr. j.l. wortman standing to one side. dr. wortman is one of the most notable and successful collectors of fossil vertebrates and was in charge of the museum's field work in this department from - .] the huge size of some of these mesozoic beasts of prey finds no parallel among their modern analogues. it is only among marine animals that we find predaceous types of such gigantic size. but among the carnivorous dinosaurs we fail to find any indications of aquatic or even amphibious habits. they might indeed wade in the water, but they could hardly be at home in it, for they were clearly not good swimmers. we must suppose that they were dry land animals or at most swamp dwellers. _dinosaur footprints._ the ancestors of the theropoda appear first in the triassic period, already of large size, but less completely bipedal than their successors. incomplete skeletons have been found in the triassic formations of germany[ ] but in this country they are chiefly known from the famous fossil footprints (or "bird-tracks" as they were at first thought to be), found in the flagstone quarries at turner's falls on the connecticut river, in the vicinity of boonton, new jersey, and elsewhere. these tracks are the footprints of numerous kinds of dinosaurs, large and small, mostly of the carnivorous group, which lived in that region in the earlier part of the age of reptiles, and much has been learned from them as to the habits of the animals that made them. the tracks ascribed to carnivorous dinosaurs run in series with narrow tread, short or long steps, here and there a light impression of tail or forefoot and occasionally the mark of the shank and pelvis when the animal settled back and squatted down to rest a moment. the modern crocodiles when they lift the body off the ground, waddle forward with the short limbs wide apart, and even the lizards which run on their hind legs have a rather wide tread. but these dinosaurs ran like birds, setting one foot nearly in front of the other, so that the prints of right and left feet are nearly in a straight line. this was on account of their greater length of limb, which made it easy for them to swing the foot directly underneath the body at each step like mammals and birds, and thus maintain an even balance, instead of wabbling from side to side as short legged animals are compelled to do. of the animals that made these innumerable tracks the actual remains found thus far in this country are exceedingly scanty. two or three incomplete skeletons of small kinds are in the yale museum, of which _anchisaurus_ is the best known. _megalosaurus._ fragmentary remains of this huge carnivorous dinosaur were found in england nearly a century ago, and the descriptions by dean buckland and sir richard owen and the restorations due to the imaginative chisel of waterhouse hawkins, have made it familiar to most english readers. unfortunately it was, and still remains, very imperfectly known. it was very closely related to the american _allosaurus_ and unquestionably similar in appearance and habits.[ ] allosaurus. the following extract is from the american museum journal for january .[ ] "although smaller than its huge contemporary brontosaurus, this animal is of gigantic proportions being feet inches in length, and feet inches high." [illustration: fig. .--mounted skeleton of allosaurus in the american museum. _after osborn_] _history of the allosaurus skeleton._ "this rare and finely preserved skeleton was collected by mr. f.f. hubbell in october , in the como bluffs near medicine bow, wyoming, the richest locality in america for dinosaur skeletons, and is a part of the great collection of fossil reptiles, amphibians and fishes gathered together by the late professor e.d. cope, and presented to the american museum in by president jesup. "shortly after the centennial exposition ( ) it had been planned that professor cope's collection of fossils should form part of a great public museum in fairmount park, philadelphia, the city undertaking the cost of preparing and exhibiting the specimens, an arrangement similar to that existing between the american museum and the city of new york.[ ] "the plan, however, fell through, and the greater part of this magnificent collection remained in storage in the basement of memorial hall in fairmount park, for the next twenty years. from time to time professor cope removed parts of the collection to his private museum in pine street, for purposes of study and scientific description. he seems, however, to have had no idea of the perfection and value of this specimen. in when the collection was purchased from his executors by mr. jesup, the writer went to philadelphia under the instructions of professor osborn, curator of fossil vertebrates, to superintend the packing and removal to the american museum. at that time the collection made by hubbell was still in memorial hall, and the boxes were piled up just as they came in from the west, never having been unpacked. professor cope's assistant, mr. geismar, informed the writer that hubbell's collection was mostly fragmentary and not of any great value. mr. hubbell's letters from the field unfortunately were not preserved, but it is likely that they did not make clear what a splendid find he had made, and as some of his earlier collections had been fragmentary and of no great interest, the rest were supposed to be of the same kind. "when the cope collection was unpacked at the american museum, this lot of boxes, not thought likely to be of much interest, was left until the last, and not taken in hand until or . but when this specimen was laid out, it appeared that a treasure had come to light. although collected by the crude methods of early days, it consisted of the greater part of the skeleton of a single individual, with the bones in wonderfully fine preservation, considering that they had been buried for say eight million years. they were dense black, hard and uncrushed, even better preserved and somewhat more complete than the two fine skeletons of allosaurus from bone-cabin quarry, the greatest treasures that this famous quarry had supplied. the great carnivorous dinosaurs are much rarer than the herbivorous kinds, and these three skeletons are the most complete that have ever been found. in all the years of energetic exploration that the late professor marsh devoted to searching for dinosaurs in the jurassic and cretaceous formations of the west, he did not obtain any skeletons of carnivorous kinds anywhere near as complete as these, and their anatomy was in many respects unknown or conjectural. by comparison of the three allosaurus skeletons with one another and with other specimens of carnivorous dinosaurs of smaller size in this and other museums, particularly in the national museum and the kansas university museum, we have been able to reconstruct the missing parts of the cope specimen with very little possibility of serious error." _evidence for combining and posing this mount._ "an incomplete specimen of brontosaurus, found by doctor wortman and professor w.c. knight of the american museum expedition of , had furnished interesting data as to the food and habits of allosaurus, which were confirmed by several other fragmentary specimens obtained later in the bone-cabin quarry. in this brontosaurus skeleton several of the bones, especially the spines of the tail vertebrae, when found in the rock, looked as if they had been scored and bitten off, as though by some carnivorous animal which had either attacked the brontosaurus when alive, or had feasted upon the carcass. when the allosaurus jaw was compared with these score marks, it was found to fit them exactly, the spacing of the scratches being the same as the spacing of the teeth. moreover, on taking out the brontosaurus vertebrae from the quarry, a number of broken off teeth of allosaurus were found lying beside them. as no other remains of allosaurus or any other animal were intermingled with the brontosaurus skeleton, the most obvious explanation was that these teeth were broken off by an allosaurus while devouring the brontosaurus carcass. many of the bones of other herbivorous dinosaurs found in the bone-cabin quarry were similarly scored and bitten off, and the teeth of allosaurus were also found close to them. "with these data at hand the original idea was conceived of combining these two skeletons, both from the same formation and found within a few miles of each other, to represent what must actually have happened to them in the remote jurassic period, and mount the allosaurus skeleton standing over the remains of a brontosaurus in the attitude of feeding upon its carcass. some modifications were made in the position to suit the exigencies of an open mount, and to accommodate the pose to the particular action; the head of the animal was lifted a little, one hind foot planted upon the carcass, while the other, resting upon the ground bears most of the weight. the fore feet, used in these animals only for fighting or for tearing their prey, not for support, are given characteristic attitudes, and the whole pose represents the allosaurus devouring the carcass and raising head and fore foot in a threatening manner as though to drive away intruders. the balance of the various parts was carefully studied and adjusted under direction of the curator. the preparation and mounting of the specimen were done by mr. adam hermann, head preparator, and his assistants, especially messrs. falkenbach and lang. [illustration: fig. .--restoration of allosaurus by c.r. knight. _after osborn_] "as now exhibited in the dinosaur hall, this group gives to the imaginative observer a most vivid picture of a characteristic scene in that bygone age, millions of years ago, when reptiles were the lords of creation, and 'nature, red in tooth and claw' had lost none of her primitive savagery, and the era of brute force and ferocity showed little sign of the gradual amelioration which was to come to pass in future ages through the predominance of superior intelligence." _appearance and habits of allosaurus._ a study of the mechanism of the allosaurus skeleton shows us in the first place that the animal is balanced on the hind limbs, the long heavy tail making an adequate counterpoise for the short compact body and head. the hind limbs are nine feet in length when extended, about equal to the length of the body and neck, and the bones are massively proportioned. when the thigh bone is set in its normal position, as indicated by the position of the scars and processes for attachment of the principal muscles (see under brontosaurus for the method used to determine this), the knee bends forward as in mammals and birds, not outward as in most modern reptiles. the articulations of the foot bones show that the animal rested upon the ends of the metapodials, as birds and many mammals do, not upon the sole of the foot like crocodiles or lizards. the flat vertebral joints show that the short compact body was not as flexible as the longer body of crocodiles or lizards, in which the articulations are of the ball and socket type showing that in them this region was very flexible. the tail also shows a limited flexibility. it could not be curled or thrown over the back, but projected out behind the animal, swinging from side to side or up and down as much as was needed for balance. the curvature of the ribs shows that the body was narrow and deep, unlike the broad flattened body of the crocodile or the less flattened but still broad body of the lizard. the loose hung jaw, articulated far back, shows by the set of its muscles that it was capable of an enormous gape; while in the skull there is evidence of a limited movement of the upper jaw on the cranial portion, intended probably to assist in the swallowing of large objects, like the double jointed jaw of a snake. as to the nature of the skin we have no exact knowledge. we may be sure that it had no bony armor like the crocodile, for remains of any such armor could not fail to be preserved with the skeletons, as it always is in fossil crocodiles or turtles. perhaps it was scaly like the skin of lizards and snakes, for the horny scales of the body are not preserved in fossil skeletons of these reptiles. but if so we might expect from the analogy of the lizard that the scales of the head would be ossified and preserved in the fossil; and there is nothing of this kind in the carnivorous dinosaurs. we can exclude feathers from consideration, for these dinosaurs have no affinities to birds, and there is no evidence for feathers in any dinosaur. probably the best evidence is that of the trachodon or duck-billed dinosaur although this animal was but distantly related to the allosaurus. in trachodon (see p. ), we know that the skin bore neither feathers nor overlapping scales but had a curiously patterned mosaic of tiny polygonal plates and was thin and quite flexible. some such type of skin as this, in default of better evidence, we may ascribe to the allosaurus. [illustration: fig. .--view in the hell creek badlands in central montana, where the tyrannosaurus skeleton was found.] as to its probable habits, it is safe to infer (see p. ), that it was predaceous, active and powerful, and adapted to terrestrial life. its methods of attack and combat must have been more like those of modern reptiles than the more intelligent methods of the mammalian carnivore. the brain cast of allosaurus indicates a brain of similar type and somewhat inferior grade to that of the modern crocodile or lizard, and far below the bird or mammal in intelligence. the keen sense of smell of the mammal, the keen vision of the bird, the highly developed reasoning power of both, were absent in the dinosaur as in the lizard or crocodile. we may imagine the allosaurus lying in wait, watching his prey until its near approach stimulates him into a semi-instinctive activity; then a sudden swift rush, a fierce snap of the huge jaws and a savage attack with teeth and claws until the victim is torn in pieces or swallowed whole. but the stealthy, persistent tracking of the cat or weasel tribe, the intelligent generalship of the wolf pack, the well planned attack at the most vulnerable point in the prey, characteristic of all the predaceous mammals, would be quite impossible to the dinosaur. by watching the habits of modern reptiles we may gain a much better idea of his capacities and limitations than if we judge only from the efficiency of his teeth and claws, and forget the inferior intelligence that animated these terrible weapons. tyrannosaurus. the "tyrant saurian" as professor osborn has named him, was the climax of evolution of the giant flesh-eating dinosaurs. it reached a length of forty-seven feet, and in bulk must have equalled the mammoth or the mastodon or the largest living elephants. the massive hind limbs, supporting the whole weight of the body, exceeded the limbs of the great proboscideans in bulk, and in a standing position the animal was eighteen to twenty feet high, as against twelve for the largest african elephants or the southern mammoth. the head (see frontispiece) is feet inches long, ft. inches deep, and ft. inches wide; the long deep powerful jaws set with teeth from to inches long and an inch wide. to this powerful armament was added the great sharp claws of the hind feet, and probably the fore feet, curved like those of eagles, but six or eight inches in length. during ten years explorations in the western cretaceous formations, mr. brown has secured for the museum three skeletons of this magnificent dinosaur, incomplete, but finely preserved. the first, found in , included the jaws, a large part of backbone and ribs, and some limb bones. the second included most of skull and jaws, backbone, ribs and pelvis and the hind limbs and feet, but not tail. the third consisted of a perfect skull and jaws, the backbone, ribs, pelvis and nearly all of the tail, but no limbs. from these three specimens it has been possible to reconstruct the entire skeleton. the exact construction of the fore feet is the only doubtful part. the fore-limb is very small relatively to the huge size of the animal, but probably was constructed much as in the _allosaurus_ with two or three large curved claws, the inner claw opposing the others. [illustration: fig. .--quarry from which the _tyrannosaurus_ skeleton was taken. american museum camp in foreground.] the missing parts of the two best skeletons have been restored, and with the help of two small models of the skeleton, a group has been made ready for mounting as the central piece of the proposed cretaceous dinosaur hall. one of the skeletons is temporarily placed in the centre of the quaternary hall, space for it in the present dinosaur hall being lacking. following is professor osborn's description of the preparation of this group:[ ] "the mounting of these two skeletons presents mechanical problems of very great difficulty. the size and weight of the various parts are enormous. the height of the head in the standing position reaches from to feet above the ground; the knee joint alone reaches feet above the ground. all the bones are massive; the pelvis, femur and skull are extremely heavy. experience with _brontosaurus_ and with other large dinosaurs proves that it is impossible to design a metallic frame in the right pose in advance of assembling the parts. even a scale restoration model of the animal as a whole does not obviate the difficulty. "accordingly in preparing to mount _tyrannosaurus_ for exhibition a new method has been adopted, namely, to _prepare a scale model of every bone in the skeleton_ and mount this small skeleton with flexible joints and parts so that all studies and experiments as to pose can be made with the models. "this difficult and delicate undertaking was entrusted to mr. erwin christman of the artistic staff of the department of vertebrate palaeontology of the museum, who has prepared two very exact models to a one-sixth scale, representing our two skeletons of _tyrannosaurus rex_, which fortunately are of exactly the same size. a series of three experiments by mr. christman on the pose of _tyrannosaurus_, under the direction of the author and curator matthew, were not satisfactory. the advice of mr. raymond l. ditmars, curator of reptiles in the new york zoological park, was sought and we thus obtained the fourth pose, which is shown in the photographs published herewith. [illustration: fig. .--model of _tyrannosaurus_ group for the cretaceous dinosaur hall.] "the fourth pose or study, for the proposed full sized mount, is that of two reptiles of the same size attracted to the same prey. one reptile is crouching over its prey (which is represented by a portion of a skeleton). the object of this depressed pose is to bring the perfectly preserved skull and pelvis very near the ground within easy reach of the visiting observer. the second reptile is advancing, and attains very nearly the full height of the animal. the general effect of this group is the best that can be had and is very realistic, particularly the crouching figure. a fifth study will embody some further changes. the upright figure is not well balanced and will be more effective with the feet closer together, the legs straighter and the body more erect. these reptiles have a series of strong abdominal ribs not shown in the models. the fourth position places the pelvis in an almost impossible position as will be noted from the ischium and pubis. "the lateral view of this fourth pose represents the animals just prior to the convulsive single spring and tooth grip which distinguishes the combat of reptiles from that of all mammals, according to mr. ditmars. "the rear view of the standing skeleton displays the peculiarly avian structure of the iliac junction with the sacral plate, characteristic of these very highly specialized dinosaurs, also the marked reduction of the upper end of the median metatarsal bone, which formerly was believed to be peculiar to _ornithomimus_." this model of the group is on exhibition with the mounted skeleton. as compared with its predecessor _allosaurus_, the _tyrannosaurus_ is much more massively proportioned throughout. the skull is more solid, the jaws much deeper and more powerful, the fore limb much smaller, the tail shorter, the hind limb straighter and the foot bones more compacted so that the animal was more strictly "digitigrade," approaching the ostriches more closely in this particular. [illustration: fig. .--skeleton of tyrannosaurus in comparison with human skeleton.] this animal probably reached the maximum of size and of development of teeth and claws of which its type of animal mechanism was capable. its bulk precluded quickness and agility. it must have been designed to attack and prey upon the ponderous and slow moving horned and armored dinosaurs with which its remains are found, and whose massive cuirass and weapons of defense are well matched with its teeth and claws. the momentum of its huge body involved a seemingly slow and lumbering action, an inertia of its movements, difficult to start and difficult to shift or to stop. such movements are widely different from the agile swiftness which we naturally associate with a beast of prey. but an animal which exceeds an average elephant in bulk, no matter what its habits, is compelled by the laws of mechanics to the ponderous movements appropriate to its gigantic size. these movements, directed and controlled by a reptilian brain, must needs be largely automatic and instinctive. we cannot doubt indeed that the carnivorous dinosaurs developed, along with their elaborately perfected mechanism for attack, an equally elaborate series of instincts guiding their action to effective purpose; and a complex series of automatic responses to the stimulus afforded by the sight and action of their prey might very well mimic intelligent pursuit and attack, always with certain limits set by the inflexible character of such automatic adjustments. but no animal as large as _tyrannosaurus_ could leap or spring upon another, and its slow stride quickening into a swift resistless rush, might well end in unavoidable impalement upon the great horns of _triceratops_, futile weapons against a small and active enemy, but designed no doubt to meet just such attacks as these. a true picture of these combats of titans of the ancient world we cannot draw; perhaps we will never be able to reconstruct it. but the above considerations may serve to show how widely it would differ from the pictures based upon any modern analogies. one may well inquire why it is that no such gigantic carnivora have evolved among the mammalian land animals. the largest predaceous quadrupeds living today are the lion and tiger. the bears although some of them are much larger, are not generally carnivorous, except for the polar bear, which is partly aquatic, preying chiefly upon seals and fish. there are indeed carnivorous whales of gigantic size, but no very large land carnivore. there were, it is true, during the tertiary and pleistocene, lions and other carnivores considerably larger than the living species. but none of them attained the size of their largest herbivorous contemporaries, or even approached it. among the dinosaurs on the other hand we find that--setting aside brontosaurus and its allies as aquatic--the predaceous kinds equalled or exceeded the largest of the herbivorous sorts. the difference is striking, and it does not seem likely that it is merely accidental. the explanation lies probably in the fact that the large herbivorous mammals are much more intelligent and active, and would be able to use their weapons of defense so as to defy the attacks of relatively slow moving giant beasts of prey, as they do also the more active but less powerful assaults of smaller ones. the elephant or the rhinoceros is in fact practically immune from the attacks of carnivora, and would still be so were the carnivora to increase in size. the large modern carnivora prey upon herbivores of medium or smaller size, which they are active enough to surprise or run down. carnivora of much larger size would be too slow and heavy in movements to catch small prey, while the larger herbivores by intelligent use of their defensive weapons could still fend them off successfully. in consequence giant carnivores would find no field for action in the cenozoic world, and hence they have not been evolved. but the giant herbivorous dinosaurs, well armed or well defended though they were, had not the intelligence to use those weapons effectively under all circumstances. thus they might be successfully attacked, at least sometimes, by the powerful although slow moving megalosaurians. the suggestion has also been made that these giant carnivores were carrion-eaters rather than truly predaceous. the hypothesis can hardly be effectively supported nor attacked. it is presented as a possible alternate. _albertosaurus._ closely allied to the _tyrannosaurus_ but smaller, about equal in size to _allosaurus_, was the _albertosaurus_ of the edmonton formation in canada. it is somewhat older than the tyrannosaur although still of the late cretacic period, and may have been ancestral to it. a fine series of limbs and feet as also skull, tail, etc., are in the museum's collections. at or about this time carnivorous dinosaurs of slightly smaller size are known to have inhabited new jersey; a fragmentary skeleton of one secured by professor cope in was described as _laelaps_ (=_dryptosaurus_).[ ] _ornitholestes._ in contrast with the _allosaurus_ and _tyrannosaurus_ this skeleton represents the smaller and more agile carnivorous dinosaurs which preyed upon the lesser herbivorous reptiles of the period. these little dinosaurs were probably common during all the age of reptiles, much as the smaller quadrupeds are today, but skulls or skeletons are rarely found in the formations known to us. the _anchisaurus_, _podokesaurus_ and other genera of the triassic period have left innumerable tracks upon the sandy shales of the newark formation, but only two or three skeletons are known. a cast of one of them is exhibited here. the original is preserved in the yale museum. in the succeeding jurassic period we have the _compsognathus_, smallest of known dinosaurs, and this _ornitholestes_ some six feet long. a cast of the _compsognathus_ skeleton is shown, the original found in the lithographic limestone of solenhofen is preserved in the munich museum. the _ornitholestes_ is from the bone-cabin quarry in wyoming. the forefoot with its long slender digits is supposed to have been adapted for grasping an active and elusive prey, and the name (_ornitho-lestes_ = bird-robber) indicates that that prey may sometimes have been the primitive birds which were its contemporaries. in the cretacic period, there were also small and medium sized carnivorous dinosaurs, contemporary with the gigantic kinds; a complete skeleton of _ornithomimus_ at the entrance to the dinosaur hall finely illustrates this group. in appearance most of these small dinosaurs must have suggested long-legged bipedal lizards, running and walking on their hind limbs, with the long tail stretched out behind to balance the body. from what we know of their tracks it seems that they walked or ran with a narrow treadway, the footsteps almost in the middle line of progress. they did not hop like perching birds, nor did they waddle like most living reptiles. occasionally the tail or fore feet touched the ground as they walked; and when they sat down, they rested on the end of the pubic bones and on the tail. so much we can infer from the footprint impressions. the general appearance is shown in the restorations of _ornitholestes_, _compsognathus_ and _anchisaurus_ by charles knight. [illustration: fig. .--skeleton of _ornitholestes_ a small carnivorous dinosaur of the jurassic period. american museum no. .] [illustration: fig. .--restoration of _ornitholestes_, by c.r. knight under direction of professor osborn. _after osborn_] _ornithomimus._ the skeleton of this animal from the cretacic of alberta was found by the museum expedition of . it is exceptionally complete, and has been mounted as a panel, in position as it lay in the rock, and with considerable parts of the original sandstone matrix still adherent. the long slender limbs, long neck, small head and toothless jaws are all singularly bird-like, and afford a striking contrast to the tyrannosaurus. at the time of writing, its adaptation and relationships have not yet been thoroughly investigated. [illustration: fig. .--mounted skeleton of brontosaurus in the american museum.] footnotes: [footnote : this is still doubtful in _tyrannosaurus_. a number of very curious plates were found with one specimen in a quarry. b. brown, .] [footnote : quite recently a series of more or less complete skeletons have been secured from the upper triassic (keuper) near halberstadt in germany. they are not true megalosaurians, but primitive types (pachypodosauria) ancestral to both these and the sauropoda. probably many of the connecticut footprints were made by animals of this primitive group. _anchisaurus_ certainly belongs to it.] [footnote : it is evidently "the dinosaur" of sir conan doyle's "lost world" but the vivid description which the great english novelist gives of its appearance and habits, based probably upon the hawkins restoration, is not at all in accord with inferences from what is now known of these animals. see p. .] [footnote : allosaurus, a carnivorous dinosaur, and its prey. by w.d. matthew. am. mus. nat. hist. jour. vol. viii, pp. - , pl. .] [footnote : the cost of preparation is now defrayed by the museum.] [footnote : tyrannosaurus, restoration and model of the skeleton. by henry fairfield osborn. bull. amer. mus. nat. hist., , vol. xxxii, art. iv, pp. - .] [footnote : since these lines were written the museum has secured finely preserved skeletons of two or more kinds of carnivorous dinosaurs from the belly river formation in canada.] chapter v. the amphibious dinosaurs, brontosaurus, diplodocus, etc. sub-order opisthocoelia (cetiosauria or sauropoda). these were the giant reptiles par-excellence, for all of them were of enormous size, and some were by far the largest of all four-footed animals, exceeded in bulk only by the modern whales. in contrast to the carnivorous dinosaurs these are quadrupedal, with very small head, blunt teeth, long giraffe-like neck, elephantine body and limbs, long massive tail prolonged at the tip into a whip-lash as in the lizards. like the elephant they have five short toes on each foot, probably buried in life in a large soft pad, but the inner digits bear large claws, blunt like those of turtles, one in the fore foot, three in the hind foot. to this group belong the brontosaurus and diplodocus, the camarasaurus, morosaurus and other less known kinds. all of them lived during the late jurassic and comanchic ("lower cretaceous") and belong to the older of the two principal dinosaur faunas. they were contemporaries of the allosaurus and megalosaurus, the stegosaurus and iguanodon, but unlike the carnivorous and beaked dinosaurs they became wholly extinct before the upper or true cretacic, and left no relatives to take part in the final epoch of expansion and prosperity of the dinosaurian race at the close of the reptilian era. [illustration: fig. .--skeletons of _brontosaurus_ (above) and _diplodocus_ (below) in the american museum. the parts preserved in these specimens are shaded. scale, feet= inch.] brontosaurus. the following description of the brontosaurus skeleton in the american museum was first published in the american museum journal of april, :[ ] "the brontosaurus skeleton, the principal feature of the hall, is sixty-six feet eight inches long. (the weight of the animal when alive is estimated by w.k. gregory at tons). about one-third of the skeleton including the skull is restored in plaster modelled or cast from other incomplete skeletons. the remaining two-thirds belong to one individual, except for a part of the tail, one shoulder-blade and one hind limb, supplied from another skeleton of the same species. "the skeleton was discovered by mr. walter granger of the museum expedition of , about nine miles north of medicine bow, wyoming. it took the whole of the succeeding summer to extract it from the rock, pack it, and ship it to the museum. nearly two years were consumed in removing the matrix, piecing together and cementing the brittle and shattered petrified bone, strengthening it so that it would bear handling, and restoring the missing parts of the bones in tinted plaster. the articulation and mounting of the skeleton and modelling of the missing bones took an even longer time, so that it was not until february, , that the brontosaurus was at last ready for exhibition. [illustration: fig. .--excavating the _brontosaurus_ skeleton. the upper photograph shows the anterior ribs of one side still lying in position. the backbone is being prepared for removal, the sections each containing three vertebrae, partly cased in plaster and burlap (see chapter xi.) the lower photograph shows a later stage of progress, the blocks being undercut and nearly ready to turn over and incase the under side. strips of wood have been pasted into each section to strengthen it.] "it will appear, therefore, that the collection, preparation and mounting of this gigantic fossil has been a task of extraordinary difficulty. no museum has ever before attempted to mount so large a fossil skeleton, and the great weight and fragile character of the bones made it necessary to devise especial methods to give each bone a rigid and complete support as otherwise it would soon break in pieces from its own weight. the proper articulating of the bones and posing of the limbs were equally difficult problems, for the amphibious dinosaurs, to which this animal belongs, disappeared from the earth long before the dawn of the age of mammals, and their nearest relatives, the living lizards, crocodiles, etc., are so remote from them in either proportions or habits that they are unsatisfactory guides in determining how the bones were articulated and are of but little use in posing the limbs and other parts of the body in positions that they must have taken during life. nor among the higher animals of modern times is there one which has any analogy in appearance or habits of life to those which we have been obliged by the study of the skeleton to ascribe to the brontosaurus. "as far as the backbone and ribs were concerned, the articulating surfaces of the bones were a sufficient guide to enable us to pose this part of the skeleton properly. the limb joints, however, are so imperfect that we could not in this way make sure of having the bones in a correct position. the following method, therefore, was adopted. "a dissection and thorough study was made by the writer, with the assistance of mr. granger, of the limbs of alligators and other reptiles, and the position, size and action of the principal muscles were carefully worked out. then the corresponding bones of the brontosaurus were studied, and the position and size of the corresponding muscles were worked out, so far as they could be recognized from the scars and processes preserved on the bone. the brontosaurus limbs were then provisionally articulated and posed, and the position and size of each muscle were represented by a broad strip of paper extending from its origin to its insertion. the action and play of the muscles on the limb of the brontosaurus could then be studied, and the bones adjusted until a proper and mechanically correct pose was reached. the limbs were then permanently mounted in these poses, and the skeleton as it stands is believed to represent, as nearly as study of the fossil enables us to know, a characteristic position that the animal actually assumed during life.... "in proportions and appearance the brontosaurus was quite unlike any living animal. it had a long thick tail like the lizards and crocodiles, a long, flexible neck like an ostrich, a thick short, slab-sided body and straight, massive, post-like limbs suggesting the elephant, and a remarkably small head for the size of the beast. the ribs, limb-bones and tail-bones are exceptionally solid and heavy; the vertebrae of the back and neck, and the skull, on the contrary are constructed so as to combine the minimum of weight with the large surface necessary for the attachment of the huge muscles, the largest possible articulating surfaces, and the necessary strength at all points of strain. for this purpose they are constructed with an elaborate system of braces and buttresses of thin bony plates connecting the broad articulating surfaces and muscular attachments, all the bone between these thin plates being hollowed into a complicated system of air-cavities. this remarkable structure can be best seen in the unmounted skeleton of _camarasaurus_, another amphibious dinosaur." (the scientific name _camarasaurus_=chambered lizard, has reference to this peculiarity of construction.) "the teeth of the brontosaurus indicate that it was an herbivorous animal, feeding on soft vegetable food. three opinions as to the habitat of amphibious dinosaurs have been held by scientific authorities. the first, advocated by professor owen, who described the first specimens found sixty years ago ( - ) and supported especially by professor cope, has been most generally adopted. this regards the animals as spending their lives entirely in shallow water, partly immersed, wading about on the bottom, or perhaps occasionally swimming, but unable to emerge entirely upon dry land.[ ] more recently, professor osborn has advocated the view that they resorted occasionally to the land for egg laying or other purposes, and still more recently the view has been taken by mr. riggs and the late professor hatcher that they were chiefly terrestrial animals. the writer inclines to the view of owen and cope, whose unequalled knowledge of comparative anatomy renders their opinion on this doubtful question especially authoritative. [illustration: fig. .--restoration of brontosaurus by c.r. knight, under direction of professor osborn. _after osborn_] "the contrast between the massive structure of the limb-bones, ribs and tail, and the light construction of the backbone, neck and skull, suggests that the animal was amphibious, living chiefly in shallow water, where it could wade about on the bottom, feeding upon the abundant vegetation of the coastal swamps and marshes, and pretty much out of reach of the powerful and active carnivorous dinosaurs which were its principal enemies. the water would buoy up the massive body and prevent its weight from pressing too heavily on the imperfect joints of the limb and foot bones, which were covered during life with thick cartilage, like the joints of whales, sea-lizards and other aquatic animals. if the full weight of the animal came on these imperfect joints the cartilage would yield and the ends of the bones would grind against each other, thus preventing the limb from moving without tearing the joint to pieces. the massive, solid limb and foot bones weighted the limbs while immersed in water, and served the same purpose as the lead in a diver's shoes, enabling the brontosaurus to walk about firmly and securely under water. on the other hand, the joints of the neck and back are exceptionally broad, well fitting and covered with a much thinner surface of cartilage. the pressure was thus much better distributed over the joint, and the full weight of the part of the animal above water (reduced as it was by the cellular construction of the bones) might be borne on these joints without the cartilage giving way. "looking at the mounted skeleton we may see that if a line be drawn from the hip joint to the shoulder-blade, all the bones below this are massive, all above (including neck and head) are lightly constructed. this line may be taken to indicate the average water-line, so to speak, of this leviathan of the shallows. the long neck would enable the animal, however, to wade to a considerable depth, and it might forage for food either in the branches or the tops of trees, or more probably, among the soft succulent water-plants of the bottom. the row of short spoon-shaped stubby teeth around the front of the mouth would serve to bite or pull off soft leaves and water-plants, but the animal evidently could not masticate its food, and must have swallowed it without chewing as do modern reptiles and birds. "the brain-case occupies only a small part of the back of the skull, so that the brain must have been small even for a reptile, and its organization (as inferred from the form of the brain-case) indicates a very low grade of intelligence. much larger than the brain proper was the spinal cord, especially in the region of the sacrum, controlling most of the reflex and involuntary actions of the huge organism. hence we can best regard the brontosaurus as a great, slow-moving animal automaton, a vast storehouse of organized matter directed chiefly or solely by instinct, and to a very limited degree, if at all, by conscious intelligence. its huge size and its imperfect organization, compared with the great quadrupeds of today, rendered its movements slow and clumsy; its small and low brain shows that it must have been automatic, instinctive and unintelligent." _composition of the brontosaurus skeleton._ "the principal specimen, no. , is from the nine mile crossing of the little medicine bow river, wyoming. it consists of the th, th, and th to th cervical vertebrae, st to th dorsal and rd to th caudal vertebrae, all the ribs, both coracoids, parts of sacrum and ilia, both ischia and pubes, left femur and astragalus, and part of left fibula. the backbone and most of the neck of this specimen were found articulated together in the quarry, the ribs of one side in position, the remainder of the bones scattered around them, and some of the tail bones weathered out on the surface. "from no. , found at como bluffs, wyo., were supplied the right scapula, th dorsal vertebra, and right femur and tibia. "no. , from bone-cabin quarry, wyoming, supplied the th to th caudal vertebrae, no. , from the same locality the metatarsals of the right hind foot; and a few toe bones are supplied from other specimens. [illustration: fig. .--skull of _diplodocus_ from bone-cabin quarry, north of medicine bow, wyoming.] "the remainder of the skeleton is modelled in plaster, the scapula, humerus, radius and ulna from the skeleton in the yale museum, the rest principally from specimens in our own collections. the modelling of the skull is based partly upon specimens in the yale museum, but principally upon the complete skull of morosaurus shown in another case. "mounted by a. hermann, completed feb. , ." _diplodocus._ the _diplodocus_ nearly equalled the brontosaurus in bulk and exceeded it in length. a skeleton in the carnegie museum at pittsburgh measures feet in total length; although the mount is composed from several individuals these proportions are probably not far from correct. the skull is smaller and differently shaped and the teeth are of quite different type. in the american museum of natural history, a partial skeleton is exhibited in the wall case to the left of the entrance of the dinosaur hall, and in an a-case near by are skulls of _diplodocus_ and _morosaurus_ and a model of the skull of _brontosaurus_. the diplodocus skull is widely different from the other two in size and proportions and in the characters of teeth. when the first remains of these amphibious dinosaurs were found in the oxford clays of england, they were considered by richard owen to be related to the crocodiles, and named opisthocoelia. subsequently the finding of complete skeletons in this country led cope and marsh to place them with the true dinosaurs and the latter named them sauropoda.[ ] remains of these animals have also been found in india, in german east africa, in madagascar, and in south america, so that they were evidently widely distributed. in the northern world they survived until the comanchic or lower cretaceous period, but in the southern continents they may have lived on into the upper cretaceous or true cretacic. some of the remains recently found in german east africa indicate an animal exceeding either _brontosaurus_ or _diplodocus_ in bulk. [illustration: fig. .--the largest known dinosaur. sketch reconstruction of _brachiosaurus_, from specimens in the field museum in chicago, and the natural history museum in berlin.] at the date of writing this handbook only preliminary accounts have been given of the marvellous finds made near tendaguru by the expedition from berlin. from these it appears that in length of neck and fore limb this east african dinosaur greatly exceeded either _brontosaurus_ or _diplodocus_. the hinder parts of the skeleton however, were relatively small. the proportions and measurements given tally closely with the american _brachiosaurus_, a gigantic sauropod whose incomplete remains are preserved in the field museum in chicago and to this genus the berlin authorities now refer their largest and finest skeleton. if the berlin specimens are correctly referred to _brachiosaurus_ they indicate an animal somewhat exceeding _diplodocus_ or _brontosaurus_ in total bulk but distinguished by much longer fore limbs and an immensely long neck--a giraffe-like wader adapted to take refuge in deeper waters, more out of reach of the fierce carnivores of the land.[ ] footnotes: [footnote : the mounted skeleton of brontosaurus, by w.d. matthew, amer. mus. jour. vol. v, pp. - , figs. - .] [footnote : professor williston makes the following criticism of this theory: "i cannot agree with this view--the animals _must_ have laid their eggs upon land--for the reason that reptile eggs cannot hatch in water. s.w.w." but with deference to williston's high authority i may note that there is no evidence that the sauropoda were egg-laying reptiles. they, or some of them, may have been viviparous like the ichthyosaurus.] [footnote : european palaeontologists, especially huxley and seeley in england, had also recognized their true relationships, and seeley's term cetiosauria has precedence over sauropoda, although the latter is in common use.] [footnote : it is of interest to observe that in this group of sauropoda, the brachiosauridæ, the neural spines of the vertebrae are much simpler and narrower than in the brontosaurus and diplodocus. the attachments were thus less extensive for the muscles of the back, indicating that these muscles were less powerful. this difference is correlated by professor williston with the longer fore limbs of the brachiosaurus, as signifying that the animal was less able, as indeed he had less need, to rise up upon the hind limbs, in comparison with diplodocus or brontosaurus in which the fore limbs were relatively short.] chapter vi. the beaked dinosaurs. order orthopoda (ornithischia or predentata.) the peculiar feature of this group of dinosaurs is the horny beak or bill. the bony core sutured to the front of the upper and lower jaws was covered in life by a horny sheath, as in birds or turtles. but this is not the only feature in which they came nearer to birds than do the other dinosaurs. the pelvic or hip bones are much more bird-like in many respects, especially the backward direction of the pubic bone, the presence of a prepubis, in the number of vertebrae coössified into a solid sacrum, in the proportions of the ilium and so on. various features in the anatomy of the head, shoulder-blades and hind limbs are equally suggestive of birds, and it seems probable that the earliest ancestors of the birds were very closely related to the ancestors of this group of dinosaurs. but the ancestral birds became adapted to flying, the ancestral predentates to terrestrial life, and in their later development became as widely diversified in form and habits as the warm-blooded quadrupeds which succeeded them in the age of mammals. [illustration: fig. .--skulls of iguanodont and trachodont dinosaurs. _iguanodon_ and _camptosaurus_ of the jurassic and comanchic; _kritosaurus_ and _corythosaurus_ of the middle cretacic (belly river); _saurolophus_ of the late cretacic (edmonton); _trachodon_ of the latest cretacic (lance). the iguanodon is european, the others north american. all / natural size.] these beaked dinosaurs were, so far as we can tell, all vegetarians. unlike the birds, they retained their teeth and in some cases converted them into a grinding apparatus which served the same purpose as the grinders of herbivorous quadrupeds. it is interesting to observe the different way in which this result is attained. in the mammals the teeth, originally more complex in construction and fewer in number, are converted into efficient grinders by infolding and elongation of the crown of each tooth so as to produce on the wearing surface a complex pattern of enamel ridges with softer dentine or cement intervening, making a series of crests and hollows continually renewed during the wear of the tooth. in the reptile the teeth, originally simple in construction but more numerous and continually renewed as they wear down and fall out,[ ] are banked up in several close packed rows, the enamel borders and softer dentine giving a wearing surface of alternating crests and hollows continually renewed, and reinforced from time to time, by the addition of new rows of teeth to one side, as the first formed rows wear down to the roots. this is the best illustrated in the _trachodon_ (see fig. ); the other groups have not so perfect a mechanism. a. the iguanodonts: iguanodon, camptosaurus. _sub-order ornithopoda or iguanodontia._ in the early days of geology, about the middle of the nineteenth century, bones and footprints of huge extinct reptiles were found in the rocks of the weald in south-eastern england. they were described by mantell and owen and shown to pertain to an extinct group of reptiles which owen called the dinosauria. so different were these bones from those of any modern reptiles that even the anatomical learning of the great english palaeontologist did not enable him to place them all correctly or reconstruct the true proportions of the animal to which they belonged. with them were found associated the bones of the great carnivorous dinosaur _megalosaurus_; and the weird reconstructions of these animals, based by waterhouse hawkins upon the imperfect knowledge and erroneous ideas then prevailing, must be familiar to many of the older readers of this handbook. life size restorations of these and other extinct animals were erected in the grounds of the crystal palace at sydenham, london, and in central park, new york. those in london still exist, so far as the writer is aware, but the stern mandate of a former mayor of new york ordered the destruction of the central park models, not indeed as incorrect scientifically, but as inconsistent with the doctrines of revealed religion, and they were accordingly broken up and thrown into the waters of the park lake. small replicas of these early attempts at restoring dinosaurs may still be seen in some of the older museums in this country and abroad. [illustration: fig. .--skeleton of camptosaurus, an american relative of the iguanodon.] the real construction of the iguanodon was gradually built up by later discoveries, and in an extraordinary find in a coal mine at bernissart in belgium brought to light no less than seventeen skeletons more or less complete. these were found in an ancient fissure filled with rocks of comanchic age, traversing the carboniferous strata in which the coal seam lay, and with them were skeletons of other extinct reptiles of smaller size. the open fissure had evidently served as a trap into which these ancient giants had fallen, and either killed by the fall or unable to escape from the pit, their remains had been subsequently covered up by sediments and the pit filled in to remain sealed up until the present day. these skeletons, unique in their occurrence and manner of discovery, are the pride of the brussels museum of natural history, and, together with the earlier discoveries, have made the _iguanodon_ the most familiar type of dinosaur to the people of england and western europe. [illustration: fig. .--teeth of the duck-billed dinosaur _trachodon_. the dental magazine has been removed from the lower jaw and is seen to consist of several close-set rows of numerous small pencil-like teeth which are pushed up from beneath as they wear off at the grinding surface.] _camptosaurus._ the american counterpart of the iguanodons of europe was the _camptosaurus_, nearly related and generally similar in proportions but including mostly smaller species, and lacking some of the peculiar features of the old world genus. in the national museum at washington, are mounted two skeletons of _camptosaurus_, a large and a small species, and in the american museum a skeleton of a small species. it suggests a large kangaroo in size and proportions, but the three-toed feet, with hoof-like claws, the reptilian skull, loosely put together, with lizard-like cheek teeth and turtle beak indicate a near relative of the great _iguanodon_. _thescelosaurus._ the iguanodont family survived until the close of the age of reptiles, with no great change in proportions or characters. its latest member is _thescelosaurus_, a contemporary of _triceratops_. partial skeletons of this animal are shown in the dinosaur hall; a more complete one is in the national museum. footnotes: [footnote : trachodont teeth never drop out, they are completely consumed. only in the iguanodonts and ceratopsia are they shed.--b. brown.] chapter vii. the beaked dinosaurs (continued). b. the duck billed dinosaurs,--trachodon, saurolophus, etc. _sub-order ornithopoda; family trachodontidæ._ these animals of the upper cretaceous are probably descended from the iguanodonts of an older period. but the long ages that intervened, some millions of years, have brought about various changes in the race, not so much in general proportions as in altering the form and relations of various bones of skull and skeleton and perfecting their adaptation to a somewhat different habit of life, so that they must be regarded as descendants perhaps, but certainly rather distant relatives, of the older group. we know more about the trachodonts than any other dinosaurs. for not only are the skeletons more frequently found articulated, but parts of the skin are not uncommonly preserved with them, and in one specimen at least, so much of the skin is preserved that it may fairly be called a "dinosaur mummy." this specimen of _trachodon_ is in the american museum, and beside it are two fine mounted skeletons of the largest size. there is also on exhibition a panel mount of a nearly related genus, _saurolophus_ the skeleton lying as it was found in the rock, and a fine skeleton of a third genus _corythosaurus_ with the skin partly preserved on both sides of the crushed and flattened body stands beside it. in the _tyrannosaurus_ group when completed will appear a fourth skeleton of the _trachodon_. several skulls and incomplete skeletons on exhibition and other skeletons not yet prepared add to the museum collection of this group. trachodon skeletons may also be found in the museums of new haven, washington, frankfurt-on-the-main, london and paris, but nowhere a series comparable to that displayed at the american museum. the trachodon group. the following description of the trachodon group is by mr. barnum brown and first appeared in the american museum journal for april :[ ] "this group takes us back in imagination to the cretaceous period, more than three millions of years ago, when trachodonts were among the most numerous of the dinosaurs. two members of the family are represented here as feeding in the marshes that characterized the period, when one is startled by the approach of a carnivorous dinosaur, tyrannosaurus, their enemy, and rises on tiptoe to look over the surrounding plants and determine the direction from which it is coming. the other trachodon, unaware of danger, continues peacefully to crop the foliage. perhaps the erect member of the group had already had unpleasant experiences with hostile beasts, for a bone of its left foot bears three sharp gashes which were made by the teeth of some carnivorous dinosaur. [illustration: fig. .--mounted skeletons of _trachodon_ in the american museum. height of standing skeleton feet, inches.] "by thus grouping the skeletons in lifelike attitudes, the relation of the different bones can best be shown, but these of course are only two of the attitudes commonly taken by the creatures during life. mechanical and anatomical considerations, especially the long straight shafts of the leg bones, indicate that dinosaurs walked with their limbs straight under the body, rather than in a crawling attitude with the belly close to the ground, as is common among living reptiles. "trachodonts lived near the close of the age of reptiles in the upper cretaceous and had a wide geographical distribution, their remains having been found in new jersey, mississippi and alabama, but more commonly in wyoming, montana, and the dakotas. a suggestion of the great antiquity of these specimens is given by the fact that since the animals died layers of rock aggregating many thousand feet in vertical thickness have been deposited along the atlantic coast. "the bones of the erect specimen are but little crushed and a clear conception of the proportions of the animal can best be obtained from this specimen. it will be seen that the trachodon was shaped somewhat like a kangaroo, with short fore legs, long hind legs, and a long tail. the fore limbs are reduced indeed to about one-sixth the size of the hind limbs and judging from the size and shape of the foot bones the front legs could not have borne much weight. they were probably used in supporting the anterior portion of the body when the creature was feeding, and in aiding it to recover an upright position. the specimen represented as feeding is posed so that the fore legs carry very little of the weight of the body. there are four toes on the front foot but the thumb is greatly reduced and the fifth digit or little finger, is absent." (subsequent discoveries have shown that the arrangement of the digits made by marsh and followed in this skeleton is incorrect. it is the first digit that is absent, and the fifth is reduced.) "the hind legs are massive and have three well developed toes ending in broad hoofs. the pelvis is lightly constructed with bones elongated like those of birds. the long deep compressed tail was particularly adapted for locomotion in the water. it may also have served to balance the creature when standing erect on shore. the broad expanded lip of bone known as the fourth trochanter, on the inner posterior face of the femur or thigh bone was for the attachment of powerful tail muscles similar to those which enable the crocodile to move its tail from side to side with such dexterity. this trochanter is absent from the thigh bones of land-inhabiting dinosaurs with short tails, such as _stegosaurus_ and _triceratops_. the tail muscles were attached to the vertebrae by numerous rod-like tendons which are preserved in position as fossils on the erect skeleton. trachodonts are thought to have been expert swimmers. unlike other dinosaurs their remains are frequently found in rocks that were formed under sea water probably bordering the shores but nevertheless containing typical sea shells. "the elaborate dental apparatus is such as to show clearly that trachodonts were strictly herbivorous creatures. the mouth was expanded to form a broad duck-like bill which during life was covered with a horny sheath, as in birds and turtles. each jaw is provided with from to vertical and from to horizontal rows of teeth, so that there were more than teeth altogether in both jaws. "among living saurians, or reptiles, the small south american iguana _amblyrhynchus_ may be compared in some respects with the trachodons notwithstanding the difference in size. these modern saurians live in great numbers on the shores of the galapagos islands off the coast of chile. they swim out to sea in shoals and feed exclusively on seaweed which grows on the bottom at some distance from shore. the animal swims with perfect ease and quickness by a serpentine movement of its body and flattened tail, its legs meanwhile being closely pressed to its side and motionless. this is also the method of propulsion of crocodiles when swimming. "the carnivorous or flesh-eating dinosaurs that lived on land, such as _allosaurus_ and _tyrannosaurus_, were protected from foes by their sharp biting teeth, while the land-living herbivorous forms were provided with defensive horns, as in _triceratops_, sharp spines as in _stegosaurus_ or were completely armored as in _ankylosaurus_. trachodon was not provided with horns, spines or plated armor, but it was sufficiently protected from carnivorous land forms by being able to enter and remain in the water. its skin was covered with small raised scales, pentagonal in form on the body and tail, where they were largest, with smaller reticulations over the joints but never overlapping as in snakes or fishes. a trachodon skeleton was recently found with an impression of the skin surrounding the vertebrae which is so well preserved that it gives even the contour of the tail as is shown in the illustration (fig. ). "during the existence of the trachodonts the climate of the northern part of north america was much warmer than it is at present, the plant remains indicating a climate for wyoming and montana similar to what now prevails in southern california. palm leaves resembling the palmetto of florida are frequently found in the same rocks with these skeletons. here occur also such, at present, widely separated trees as the gingko now native of china, and the sequoia now native of the pacific coast. fruits and leaves of the fig tree are also common, but most abundant among the plant remains are the equisetae or horsetail rushes, some species of which possibly supplied the trachodons with food. [illustration: fig. .--restoration of the duck-billed dinosaur trachodon. this restoration, made by mr. knight under supervision of professor osborn, embodies the latest evidence as to the structure and characteristic poses of these animals, the character of the skin and their probable habits and environment. _after osborn_] "impressions of the more common plants found in the rocks of this period with sections of the tree trunks showing the woody structure will be [have been] introduced into the group as the ground on which the skeletons stand. in the rivers and bayous of that remote period there also lived many kinds of unios or fresh-water clams, and other shells, the casts of which are frequently found with trachodon bones. the fossil trunk of a coniferous tree was found in wyoming, which was filled with groups of wood-living shells similar to the living teredo. these also will be introduced in the ground-work. "the skeleton mounted in a feeding posture was one of the principal specimens in the cope collection, which, through the generosity of the late president jesup, was purchased and given to the american museum. it was found near the moreau river, north of the black hills, south dakota, in , by dr. j.l. wortman and mr. r.s. hill, collectors for professor cope. the erect skeleton came from crooked creek, central montana, and was found by a ranchman, mr. oscar hunter, while riding through the bad lands with a companion in . the specimen was partly exposed, with backbone and ribs united in position. the parts that were weathered out are much lighter in color than the other bones. their large size caused some discussion between the ranchmen and to settle the question, mr. hunter dismounted and kicked off all the tops of the vertebrae and rib-heads above ground, thereby proving by their brittle nature that they were stone and not buffalo bones as the other man contended. the proof was certainly conclusive, but it was extremely exasperating to the subsequent collectors. another ranchman, mr. alfred sensiba, heard of the find and knowing that it was valuable 'traded' mr. hunter a six-shooter for his interest in it. the specimen was purchased from messrs. sensiba brothers and excavated by the american museum in ." [illustration: fig. .--the dinosaur mummy. skeleton of a trachodon preserving the skin impressions over a large part of the body. _after osborn_] the dinosaur "mummy." we all _believe_ that the dinosaurs existed. but to realize it is not so easy. even with the help of the mounted skeletons and restorations, they are somewhat unreal and shadowy beings in the minds of most of us. but this "dinosaur mummy" sprawling on his back and covered with shrunken skin--a real specimen, not restored in any part--brings home the reality of this ancient world even as the mummy of an ancient egyptian brings home to us the reality of the world of the pharaohs. the description of this unique skeleton by professor henry fairfield osborn first appeared in the museum journal for january .[ ] "two years ago ( ) through the jesup fund, the museum came into possession of a most unique specimen discovered in august , by the veteran fossil hunter charles h. sternberg of kansas. it is a large herbivorous dinosaur of the closing period of the age of reptiles and is known to palaeontologists as _trachodon_ or more popularly as the 'duck-billed dinosaur.' "the skeleton or hard parts of these very remarkable animals had been known for over forty years, and a few specimens of the epidermal covering, but it was not until the discovery of the sternberg specimen that a complete knowledge of the outer covering of these dinosaurs was gained. it appears probable that in a number of cases these priceless skin impressions were mostly destroyed in removing the fossil specimens from their surroundings because the explorers were not expecting to find anything of the kind. altogether seven specimens have been discovered in which these delicate skin impressions were partly preserved, but the 'trachodon mummy' far surpasses all the others, as it yields a nearly complete picture of the outer covering. "the reason the sternberg specimen (_trachodon annectens_) may be known as a dinosaur 'mummy' is that in all the parts of the animal which are preserved (_i.e._ all except the hind limbs and the tail), the epidermis is shrunken around the limbs, tightly drawn along the bony surfaces, and contracted like a great curtain below the chest area. this condition of the epidermis suggests the following theory of the deposition and preservation of this wonderful specimen, namely: that after dying a natural death the animal was not attacked or preyed upon by its enemies, and the body lay exposed to the sun entirely undisturbed for a long time, perhaps upon a broad sand flat of a stream in the low-water stage; the muscles and viscera thus became completely dehydrated, or desiccated by the action of the sun, the epidermis shrank around the limbs, was tightly drawn down along all the bony surfaces, and became hardened and leathery, on the abdominal surfaces the epidermis was certainly drawn within the body cavity, while it was thrown into creases and folds along the sides of the body owing to the shrinkage of the tissues within. at the termination of a possible low-water season during which these processes of desiccation took place, the 'mummy' may have been caught in a sudden flood, carried down the stream and rapidly buried in a bed of fine river sand intermingled with sufficient elements of clay to take a perfect cast or mold of all the epidermal markings before any of the epidermal tissues had time to soften under the solvent action of the water. in this way the markings were indicated with absolute distinctness, ... the visitor will be able by the use of the hand glass to study even the finer details of the pattern, although of course there is no trace either of the epidermis itself, which has entirely disappeared, or of the pigmentation or coloring, if such existed. "although attaining a height of fifteen to sixteen feet the trachodons were not covered with scales or a bony protecting armature, but with dermal tubercles of relatively small size, which varied in shape and arrangement in different species, and not improbably associated with this varied epidermal pattern there was a varied color pattern. the theory of a color pattern is based chiefly upon the fact that the larger tubercles concentrate and become more numerous on all those portions of the body exposed to the sun, that is, on the outer surfaces of the fore and hind limbs, and appear to increase also along the sides of the body and to be more concentrated on the back. on the less exposed areas, the under side of the body and the inner sides of the limbs, the smaller tubercles are more numerous, the larger tubercles being reduced to small irregularly arranged patches. from analogy with existing lizards and snakes we may suppose, therefore, that the trachodons presented a darker appearance when seen from the back and a lighter appearance when seen from the front. [illustration: fig. .--the dinosaur mummy. detail of skin of under side of body. _after osborn_] [illustration: fig. .--skin impression from the tail of a _trachodon_. the impressions appear to have been left by horny scutes or scales, not overlapping like the scales on the body of most modern reptiles, but more like the scutes on the head of a lizard.] [illustration: fig. .--skull of gila monster (_heloderma_), for comparison of surface with skin impressions of _trachodon_. enlarged to / .] "the thin character of the epidermis as revealed by this specimen favors also the theory that these animals spent a large part of their time in the water, which theory is strengthened by the fact that the diminutive fore limb terminates not in claws or hoofs, but in a broad extension of the skin, reaching beyond the fingers and forming a kind of paddle.[ ] the marginal web which connects all the fingers with each other, together with the fact that the lower side of the fore limb is as delicate in its epidermal structure as the upper, certainly tends to support the theory of the swimming rather than the walking or terrestrial function of this fore paddle as indicated in the accompanying preliminary restoration that was made by charles r. knight working under the writer's direction. one is drawn in the conventional bipedal or standing posture while the other is in a quadrupedal pose or walking position, sustaining or balancing the fore part of the body on a muddy surface with its fore feet. in the distant water a large number of animals are disporting themselves. "the designation of these animals as the 'duck-billed' dinosaurs in reference to the broadening of the beak, has long been considered in connection with the theory of aquatic habitat. the conversion of the fore limb into a sort of paddle, as evidenced by the sternberg specimen, strengthens this theory. "this truly wonderful specimen, therefore, nearly doubles our previous insight into the habits and life of a very remarkable group of reptiles." _saurolophus, corythosaurus._ in the latest cretaceous formation, the lance or triceratops beds, all the duck-billed dinosaurs are much alike, and are referred to the single genus _trachodon_. in somewhat older formations of the cretacic period there were several different kinds. _saurolophus_ has a high bony spine rising from the top of the skull; in _corythosaurus_ there is a thin high crest like the crown of a cassowary on top of the skull, and the muzzle is short and small giving a very peculiar aspect to the head. complete skeletons of these two genera are exhibited in the dinosaur hall; the _corythosaurus_ is worthy of careful study, as the skin of the body, hind limbs and tail, the ossified tendons, and even the impressions of the muscular tissues in parts of the body and tail, are more or less clearly indicated. [illustration: fig. .--skeleton of saurolophus, from upper cretacic of alberta. _after brown_] these duck-billed dinosaurs probably ranged all over north america and the northerly portions of the old world during the later cretacic. fragmentary remains have been found in new jersey and southward along the atlantic coast. a partial skeleton was described many years ago by leidy under the name of _hadrosaurus_ and restored and mounted in the museum of the philadelphia academy of sciences. _telmatosaurus_ of the gosau formation in austria also belongs to this group, and fragmentary remains have been found in the upper cretacic of belgium, england and france. footnotes: [footnote : brown, barnum. "the trachodon group." amer. mus. jour. vol. viii, pp. - , plate and text figs., .] [footnote : osborn, henry fairfield, "dinosaur mummy" amer. mus. jour. vol. xi, pp. - , illustrated, jan. .] [footnote : there is some doubt whether this was really the condition during life. w.d.m.] chapter viii. the beaked dinosaurs (continued.) c. the armored dinosaurs--stegosaurus, ankylosaurus. _sub-order stegosauria._ this group of dinosaurs is most remarkable for the massive bony armor plates, crests or spines covering the body and tail. they were more or less completely quadrupedal instead of bipedal, with straight post-like limbs and short rounded hoofed feet adapted to support the weight of the massive body and heavy armature. although so different superficially from the bird-footed biped iguanodonts they are evidently related to them, for the teeth are similar, and the horny beak, the construction of the pelvis, the three-toed hind foot and four-toed front foot all betray relationship. from what we know of them it seems probable that they evolved from iguanodont ancestors, developing the bony armor as a protection against the attacks of carnivorous dinosaurs, and modifying the proportions of limbs and feet to enable them to support its weight. they were evidently herbivorous and some of them of gigantic size. smaller kinds with less massive armor have been found in europe but the largest and most extraordinary members of this strange race are from north america. stegosaurus. this extraordinary reptile equalled the allosaurus in size, and bore along the crest of the back a double row of enormous bony plates projecting upward and somewhat outward alternately to one side and the other. the largest of these plates situated just back of the pelvis were over two feet high, two and a half long, thinning out from a base four inches thick. the tail was armed with four or more stout spines two feet long and five or six inches thick at the base. in the neck region and probably elsewhere the skin had numerous small bony nodules and some larger ones imbedded in its substance or protecting its surface. the head was absurdly small for so huge an animal, and the stiff thick tail projected backward but was not long enough to reach the ground. the hind limbs are very long and straight, the fore limbs relatively short, and the short high arched back and extremely deep and compressed body served to exaggerate the height and prominence of the great plates. the surface of these plates, covered with a network of blood-vessels, shows that they bore a covering of thick horny skin during life, which probably projected as a ridge beyond their edges and still further increased their size. the spines of the tail, also, were probably cased in horn. this extraordinary animal was a contemporary of the brontosaurus and allosaurus, and its discovery was one of the great achievements of the late professor marsh. the skeletons which he described are mounted in the yale and national museums. another skeleton was found in the famous bone-cabin quarry, near medicine bow, wyoming, by the american museum expedition of . this skeleton, at present withdrawn from lack of space, will be mounted in the jurassic dinosaur hall in the new wing now under construction. [illustration: fig. .--skull and lower jaw of armored dinosaur _ankylosaurus_, from upper cretacic (edmonton formation) of alberta. left side view. _after brown_] ankylosaurus. related to _stegosaurus_, equally huge, but very different in proportions and character of its armor was the ankylosaurus of the late cretacic. this animal, a contemporary of the tyrannosaurus and duck-billed dinosaurs was more effectively though less grotesquely armored than its more ancient relative. the body is covered with massive bony plates set close together and lying flat over the surface from head to tip of tail. while the stegosaur's body was narrow and compressed, in this animal it is exceptionally broad and the wide spreading ribs are coössified with the vertebrae, making a very solid support for the transverse rows of armor plates. the head is broad triangular, flat topped and solidly armored, the plates consolidated with the surface of the skull and overhanging sides and front, the nostrils and eyes overhung by plates and bosses of bone; and the tail ended in a blunt heavy club of massive plates consolidated to each other and to the tip of the tail vertebrae. the legs were short, massive and straight, ending probably in elephant-like feet. the animal has well been called "the most ponderous animated citadel the world has ever seen" and we may suppose that when it tucked in its legs and settled down on the surface it would be proof even against the attacks of the terrible tyrannosaur. [illustration: fig. .--_ankylosaurus_, top view of skull in fig. . _after brown_] this marvellous animal was made known to science by the discoveries of the museum parties in montana and alberta under barnum brown. fragmentary remains of smaller relatives had been discovered by earlier explorers but nothing that gave any adequate notion of its character or gigantic size. from a partial skeleton discovered in the hell creek beds of montana, and others in the edmonton and belly river formations of the red deer river, alberta, it has been possible to reconstruct the entire skeleton of the animal, save for the feet, and to locate and arrange most of the armor plates exactly. a skeleton mount from these specimens will shortly be constructed for the cretaceous dinosaur hall. _scelidosaurus, polacanthus, etc._ various armored dinosaurs, of smaller size and less heavily plated, have been described from the jurassic, comanchic and cretacic formations of europe. the best known are _scelidosaurus_ of the lower jurassic of england, and _polacanthus_ of the comanchic (wealden). _stegopelta_ of the cretaceous of wyoming is more nearly related to _ankylosaurus_. chapter ix. the beaked dinosaurs (concluded.) d. the horned dinosaurs, triceratops, etc. _sub-order ceratopsia._ in professor marsh published a brief notice of what he supposed to be a fossil bison horn found near denver, colorado. two years later the explorations of the lamented john b. hatcher in wyoming and montana resulted in the unexpected discovery that this horn belonged not to a bison but to a gigantic horned reptile, and that it belonged not in the geological yesterday as at first thought, but in the far back cretacic, millions of years ago. for mr. hatcher found complete skulls, and later secured skeletons, clearly of the dinosaurian group, but representing a race of dinosaurs whose existence, or at least their extraordinary character, had been quite unsuspected. it appeared indeed that certain teeth and skeleton bones previously discovered by professor cope were related to this new type of dinosaur, but the fragments known to the philadelphia professor gave him no idea of what the animal was like, although with his usual acumen he had discerned that they differed from any animal known to science and registered them as new under the names of _agathaumas_ and _monoclonius_ . professor marsh re-named his supposed bison "_ceratops_" (_i.e._ "horned face") and gave to the closely related skulls discovered by mr. hatcher the name of _triceratops_ (_i.e._ "three horned face"), while to the whole group he gave the name of ceratopsia. [illustration: fig. .--skulls of horned dinosaurs. the lower row, _ceratops_, _styracosaurus_, _monoclonius_, are from the middle cretacic (belly river formation) of alberta; _anchiceratops_ is from the upper cretacic (edmonton formation) of alberta; _triceratops_ and _torosaurus_ from the uppermost cretacic (lance formation) of wyoming.] these were the first of a long series of discoveries which through scientific and popular descriptions have made the horned dinosaurs familiar to the world. most of them are still very imperfectly known, and of their evolution and earlier history we know very little as yet. but we can form a fairly correct idea of their general appearance and habits and of the part they played in the world of the late cretacic. so far as known they were limited to north america. the most striking feature of the horned dinosaurs is the gigantic skull, armed with a pair of horns over the orbits and a median horn on the nasal bones in front, and with a great bony crest projecting at the back and sides. in some species the skull with its bony frill attains a length of seven or even eight feet and about three feet width; the usual length is five or six feet and the width about three. in the best known genus, _triceratops_, the paired horns are long and stout and the front horn quite short or almost absent, while in _monoclonius_ these proportions are reversed, the front horn being long while the paired horns are rudimentary. the teeth are in a single row but are broadened out into a wide grinding surface. the animal was quadrupedal, with short massive limbs and rounded elephantine feet tipped with hoofs, three in the hind foot, four in the fore foot, a short massive tail that could hardly reach the ground, a short broad-barrelled body and a short neck completely hidden on top and sides by the overhanging bony frill of the skull. in many respects these animals are suggestive far more than any other dinosaurs, of the great quadrupeds of tertiary and modern times, rhinoceroses, hippopotami, titanotheres and elephants, as in the horns they suggest the bison. for this reason although less gigantic than the brontosaurus or tyrannosaurus, less grotesque perhaps, than the stegosaurus, they are more interesting than any other dinosaurs. while thus departing far from the earlier type of the beaked dinosaurs (the iguanodonts) they are evidently descended from them. [illustration: fig. .--skull of _triceratops_ from the lance formation in wyoming, one-eighteenth natural size. the length of the horns is feet, - / inches. the rostral bone or beak, and the lower jaw, are lacking; in the illustration on the cover they have been restored in outline. this fine skull was discovered by george m. sternberg, and purchased for the museum by mr. charles lanier in .] triceratops. this is the best known of the horned dinosaurs, as various skulls and partial skeletons have been found from which it has been possible to reconstruct the entire animal. there is a mounted skeleton in the national museum, another will shortly be mounted in the american museum, and there are skulls in several american and european museums. _triceratops_ exceeded the largest rhinoceroses in bulk, equalling a fairly large elephant, but with much shorter legs. the great horns over the eyes projected forward or partly upward; in one of our skulls they are - / inches long. during life they were probably covered with horn increasing the length by six inches or perhaps a foot. the ball-like condyle for articulation of the neck lies far underneath, at the base of the frill, almost in the middle of the skull. [illustration: fig. .--skull of _monoclonius_, a horned dinosaur from the cretacic (belly river formation) of alberta. one-fifteenth natural size. the horns over the eyes are rudimentary, and the nasal horn large, reversing the proportions in _triceratops_.] _monoclonius, ceratops, etc._ the _triceratops_ and another equally gigantic horned dinosaur, _torosaurus_, were the last survivors of their race. in somewhat older formations of cretacic age are found remains of smaller kinds, some of them ancestors of these latest survivors, others collaterally related. none of these have the bony frill completely roofing over the neck as it does in _triceratops_. there is always a central spine projecting backwards and widening out at the top to the bony margin of the frill which sweeps around on each side to join bony plates that project from the sides of the skull top. this encloses an open space or "fenestra," so that the neck was not completely protected above. sometimes the margin of the frill is plain, at other times it carries a number of great spikes, like a gigantic horned lizard (_phrynosoma_). [illustration: fig. .--outline sketch restoration of _triceratops_, from the mounted skeleton in the national museum.] in _ceratops_ the horns over the eyes are large and the nasal horn small. in _monoclonius_ the nasal horn is large and those over the eyes are rudimentary. the great variety of species that has been found in recent years shows that these horned dinosaurs were a numerous and varied race of which as yet we know only a few. of their evolution we have little direct knowledge, but probably they are descended from the iguanodonts and camptosaurs of the comanchic, and their quadrupedal gait, huge heads, short tails and other peculiarities are secondary specializations, their ancestors being bipedal, long-tailed, small headed and hornless. the fine skulls of _triceratops_, _monoclonius_, _ceratops_ and _anchiceratops_ in the museum collections illustrate the variety of these remarkable animals. complete skeletons of the first two genera are being prepared for mounting and exhibition. chapter x. geographical distribution of dinosaurs. remains of dinosaurs have been found in all the continents, but chiefly in europe and north america. explorations in other parts of the world have not as yet been sufficient to show whether or not each continent developed especial kinds peculiar to it, nor to afford any reliable evidence as to whether the relations of the continents were different during the mesozoic. thus far, the carnivorous group seems most widespread, for it alone has been found in australia. the sauropods or amphibious dinosaurs have been found in europe, north america, india, madagascar, patagonia, and africa, sufficient to show that their distribution was world wide with the possible exception of australia, and probable exception of most oceanic islands (few of the modern oceanic islands existed at that time although there may well have been many others no longer extant). the beaked dinosaurs are more limited in their distribution, for none of them so far as at present known reached australia or south america. but in the present stage of discovery it would be rash to conclude that they were surely limited to the regions where they have been discovered. it is not wholly clear as yet whether the dinosaurian fauna that flourished at the end of the jurassic in the north survived to the upper cretacic in the southern continents, but present evidence points that way, and indicates that the girdle of ocean which during the cretacic depression encircled the northern world, formed a barrier which the cretacic dinosaurian fauna never succeeded in crossing. the earlier groups of beaked dinosaurs are found in both europe and america, and in the cretacic the duck-billed and armored groups are represented in both regions. the horned dinosaurs, however, are known with certainty only from north america. while most of the important fossil specimens in this country have been found in the west, more fragmentary remains have been found on the atlantic sea-board, and it is probable that they ranged all over the intervening region, wherever they found an environment suited to their particular needs. chapter xi. collecting dinosaurs. how and where they are found. the visitor who is introduced to the dinosaurs through the medium of books and pictures or of the skeletons exhibited in the great museums, finds it hard--well nigh impossible--to realize their existence. however willing he may be to accept on faith the reconstructions of the skeletons, the restorations of the animals and their supposed environment, it yet remains to him somewhat of a fairy-tale, a fanciful imaginative world peopled with ogres and dragons and belonging to the unreal "once upon a time" which has no connection with the ever present workaday world in which we live. birds and squirrels, rabbits and foxes belong to this real world because he has seen them in his walks through the woods; even elephants and rhinoceroses, though his acquaintance be limited to menagerie specimens, seem fairly real--although one recalls the farmer's comment on first seeing a giraffe in the zoological park: "there aint no sich animal." but dinosaurs--one easily realizes the state of mind that prompts the inquiry so often made by visitors to the dinosaur hall:--"they make these out of plaster, don't they?" so far as is consistent with good taste, the aim of the american museum has been to enable the visitor to see for himself how much of plaster reconstruction there is to each skeleton, and to explain in the labels what the basis was for the reconstructed parts. _how they are found._ but to the collector these extinct animals are real enough. as he journeys over the western plains he sees the various living inhabitants thereof, birds and beasts, as well as men, pursuing their various modes of life; here and there he comes across the scattered skeletons or bones of modern animals lying strewn upon the surface of the ground or half buried in the soil of a cut bank. in the shales or sandstones that underlie the soil he finds the objects of his search, skeletons or bones of extinct animals, similarly disposed, but buried in rock instead of soft soil, and exposed in cañons and gullies cut through the solid rock. each rock formation, he knows by precept and experience, carries its own peculiar fauna, its animals are different from those of the formation above and from those in the formation below. days and weeks he may spend in fruitless search following along the outcrop of the formation, through rugged badlands, along steep cañon walls, around isolated points or buttes, without finding more than a few fragments, but spurred on by vivid interest and the rainbow prospect of some new or rare find. finally perhaps, after innumerable disappointments, a trail of fragments leads up to a really promising prospect. a cautious investigation indicates that an articulated skeleton is buried at this point, and that not too much of it has "gone out" and rolled in weathered fragments down the slope. for the tedious and delicate process of disinterring the skeleton from the rock he will need to keep ever in mind the form and relations of each bone, the picture of the skeleton as it may have been when buried. the heavy ledges above are removed with pick and shovel, often with help of dynamite and a team and scraper. as he gets nearer to the stratum in which the bones lie the work must be more and more careful. a false blow with pick or chisel might destroy irreparably some important bony structure. bit by bit he traces out the position and lay of the bones, working now mostly with awl and whisk-broom, uncovering the more massive portions, blocking out the delicate bones in the rock, soaking the exposed surfaces repeatedly with thin "gum" (mucilage) or shellac, channeling around and between the bones until they stand out on little pedestals above the quarry floor. then, after the gum or shellac has dried thoroughly and hardened the soft parts, and the surfaces of bone exposed are further protected by pasting on a layer of tissue paper, it is ready for the "plaster jacket." this consists of strips of burlap dipped in plaster-of-paris and pasted over the surface of each block until top and sides, all but the pedestal on which it rests, are completely cased in, the strips being pressed and kneaded close to the surface of the block as they are laid on. when this jacket sets and dries the block is rigid and stiff enough to lift and turn over; the remains of the pedestal are trimmed off and the under surface is plastered like the rest. with large blocks it is often necessary to paste into the jacket, on upper or both sides, boards, scantling or sticks of wood to secure additional rigidity. for should the block "rack," or become shattered inside, even though no fragments were lost, the specimen would be more or less completely ruined. [illustration: fig. .--a dinosaur skeleton, prospected and ready for encasing in plaster bandages and removal in blocks. (_corythosaurus_, red deer river, alberta.)] the next stage will be packing in boxes with straw, hay or other materials, hauling to the railway and shipment to new york. arrived at the museum, the boxes are unpacked, each block laid out on a table, the upper side of its plaster jacket softened with water and cut away, and the preparation of the bone begins. always it is more or less cracked and broken up, but the fragments lie in their natural relations. each piece must be lifted out, thoroughly cleaned from rock and dirt, and the fractured surfaces cemented together again. parts of bones, especially the interior, are often rotted into dust while the harder outer surface is still preserved. the dust must be scraped out, the interior filled with a plaster cement, and the surface pieces re-set in position. very often a steel rod is set into the plaster filling the interior of a bone, to secure additional strength. after this preparation is completed, each part being soaked repeatedly with shellac until it will absorb no more, the bones can be handled and laid out for study or exhibition. then, if they are to be mounted for a fossil skeleton, comes the work of restoring the missing parts. for this a plaster composition is used. where only parts of one side are missing the corresponding parts of the other side are used for model; where both sides are missing, other individuals or nearly related species may serve as a guide. but it is seldom wise to attempt restoration of a skeleton unless at least two-thirds of it is present; composite skeletons made up of the remains of several or many individuals, have been attempted, but they are dangerous experiments in animals so imperfectly known as are most of the dinosaurs. there is too much risk of including bones that pertain to other species or genera, and of introducing thereby into the restoration a more or less erroneous concept of the animal which it represents. the same criticism applies to an overly large amount of plaster restoration. [illustration: fig. .--bone-cabin draw on little medicine river north of medicine bow, wyoming. the location of the quarry is indicated by the stack of crated specimens on the left, and close to it the low sod-covered shack where the collecting party lived. beyond the draw lies the flat rolling surface of the laramie plains and on the southern horizon the medicine bow range with elk mountain at the center.] in some instances the missing parts of a skeleton are not restored, because, even though but a small part be gone, we have no good evidence to guide in its reconstruction. this gives an imperfect and sometimes misleading concept of what the whole skeleton was like, but it is better than restoring it erroneously. usually with the more imperfect skeletons, a skull, a limb or some other characteristic parts may be placed on exhibition but the remainder of the specimen is stored in the study collections. [illustration: fig. .--american museum party at bone-cabin quarry, . seated, left to right walter granger, professor h.f. osborn, dr. w.d. matthew; standing, f. schneider, prof. r.s. lull, albert thomson, peter kaison.] _where they are found._ the chief dinosaur localities in this country are along the flanks of the rocky mountains and the plains to the eastward, from canada to texas. not that dinosaurs were any more abundant there than elsewhere. they probably ranged all over north america, and different kinds inhabited other continents as well. but in the east and the middle west, the conditions were not favorable for preserving their remains, except in a few localities. formations of this age are less extensive, especially those of the delta and coast-swamps which the dinosaurs frequented. and where they do occur, they are largely covered by vegetation and cannot be explored to advantage. in the arid western regions these formations girdle the rockies and outlying mountain chains for two-thousand miles from north to south, and are extensively exposed in great escarpments, river cañons and "badland" areas, bare of soil and vegetation and affording an immense stretch of exposed rock for the explorer. much of this area indeed is desert, too far away from water to be profitably searched under present conditions, or too far away from railroads to allow of transportation of the finds at a reasonable expense. fossils are much more common in certain parts of the region, and these localities have mostly been explored more or less thoroughly. but the field is far from being exhausted. new localities have been found and old localities re-explored in recent years, yielding specimens equal to or better than any heretofore discovered. and as the railroad and the automobile render new regions accessible, and the erosion of the formations by wind and rain brings new specimens to the surface, we may look forward to new discoveries for many years to come. in other continents, except in europe, there has been but little exploration for dinosaurs. enough is known to assure us that they will yield faunæ no less extensive and remarkable than our own. we are in fact only beginning to appreciate the vast extent and variety of these records of a past world. in a preceding chapter it was shown that the chief formations in which dinosaur remains have been found belong to the end of the jurassic and the end of the cretacic periods. the jurassic dinosaur formations skirt the rockies and outlying mountain ranges but are often turned up on edge and poorly exposed, or barren of fossils. the richest collecting ground is in the laramie plains, between the rockies and the laramie range in south-central wyoming, but important finds have also been made in colorado and utah. the cretaceous dinosaur formations extend somewhat further out on the plains to the eastward, and the best collecting regions thus far explored are in eastern wyoming, central montana and in alberta, canada. the first discovery of dinosaurs in the west. _by prof. s.w. williston._ most great discoveries are due rather to a state of mind, if i may use such an expression, than to accident. the discovery of the immense dinosaur deposits in the rocky mountains in march, , may truthfully be called great, for nothing in paleontology has equalled it, and that it was made by three observers simultaneously can not be called purely an accident. these discoverers were mr. o. lucas, then a school teacher, later clergyman; professor arthur lakes, then a teacher in the school of mines at golden, colorado; and mr. william reed, then a section foreman of the union pacific railroad at como, wyoming, later the curator of paleontology of the university of wyoming--even as i write this, comes the notice of his death,--the last. i knew them all, and the last two were long intimate friends. in the autumn of i wrote the following:[ ] "the history of their discovery (the dinosaurs) is both interesting and remarkable. for years the beds containing them had been studied by geologists of experience, under the surveys of hayden and king, but, with the possible exception of the half of a caudal vertebra, obtained by hayden and described by leidy as a species of _poikilopleuron_, not a single fragment had been recognized. this is all the more remarkable from the fact that in several of the localities i have observed acres literally strewn with fragments of bones, many of them extremely characteristic and so large as to have taxed the strength of a strong man to lift them. three of the localities known to me are in the immediate vicinity, if not upon the actual townsites of thriving villages, and for years numerous fragments have been collected by (or for) tourists and exhibited as fossil wood. the quantities hitherto obtained, though apparently so vast, are wholly unimportant in comparison with those awaiting the researches of geologists throughout the rocky mountain region. i doubt not that many hundreds of tons will eventually be exhumed." rather a startling prophecy to make within eighteen months of their discovery, but it was hardly exaggerated. it is impossible to say which of these three observers actually made the first discovery of jurassic dinosaurs; whatever doubt there is is in favor of mr. reed. professor lakes, accompanied by his friend mr. e.l. beckwith, an engineer, was, one day in march, , hunting along the "hogback" in the vicinity of morrison, colorado, for fossil leaves in the dakota cretaceous sandstone which caps the ridge, when he saw a large block of sandstone with an enormous vertebra partly imbedded in it. he discussed the nature of the fossil with his friend (so he told me) and finally concluded that it was a fossil bone. he had recently come from england and had heard of professor phillips' discoveries of similar dinosaurs there. he knew of professor marsh of yale from his recent discoveries of toothed birds in the chalk of kansas, and reported the find to him. as a result, the specimen, rock and all, was shipped to him by express at ten cents a pound! and professor marsh immediately announced the discovery of _titanosaurus_ (_atlantosaurus_) _immanis_, a huge dinosaur having a probable length of one hundred and fifteen feet and unknown height. and professor lakes was immediately set at work in the "morrison quarry" near by, whence comes the accepted name of these dinosaur beds in the rocky mountains. professor lakes once showed me the exact spot where he found his first specimen. mr. lucas, teaching his first term of a country school that spring in garden park near cañon city, as an amateur botanist was interested in the plants of the vicinity. rambling through the adjacent hills in search of them, in march, , he stumbled upon some fragments of fossil bones in a little ravine not far from the famous quarry later worked for professor marsh. he recognized them as fossils and they greatly excited, not only his curiosity, but the curiosity of the neighbors. he had heard of the late professor cope and sent some of the bones to him, who promptly labelled them _camarasaurus supremus_. the announcement of these discoveries promptly brought mr. david baldwin, professor marsh's collector in new mexico, to the scene. only a few months previously he had discovered fossil bones in the red beds of new mexico, the since famous permian deposits. he naturally explored the same beds at cañon city, immediately below the dinosaur deposits, and soon found the still very problematical _hallopus_ skeleton, at their very top, a specimen which after nearly forty years remains unique of its kind. a few years earlier professor marsh, on his way east from the tertiary deposits of western wyoming, had stopped at como, wyoming, to observe the strange salamanders, or "fish with legs" as they were widely known, so abundant in the lake at that place, about whose transformations he later wrote a paper, perhaps the only one on modern vertebrates that he ever published. while he was there mr. carlin, the station agent, showed him some fossil bone fragments, so mr. reed told me, that they had picked up in the vicinity, and about which professor marsh made some comments. but he was so engrossed with the other discoveries he was then making that he did not follow up the suggestion. had he done so the discovery of the "jurassic dinosaurs" would have been made five years earlier. mr. reed, tramping over the famous como hills after game--he had been a professional hunter of game for the construction camps of the union pacific railroad--in the winter and spring of , observed some fossil bones just south of the railway station that excited his curiosity. but he and mr. carlin did not make their discovery known to professor marsh till the following autumn, and then under assumed names, fearing that they would be robbed of their discovery. i was sent to como in november of from cañon city. i got off the train at the station after midnight, and enquired for the nearest hotel--(the station comprised two houses only), and where i could find messrs. smith and robinson. i was told that the section house was the only hotel in the place and that these gentlemen lived in the country and that there was no regular bus-line yet running to their ranch. a freshly opened box of cigars, however, helped clear up things, and i joined mr. reed the next day in opening "quarry no. " of the como hills. inasmuch as the mercury in the thermometer during the next two months seldom reached zero--upward i mean--the opening of this famous deposit was made under difficulties. that so much "head cheese," as we called it, was shipped to professor marsh was more the fault of the weather and his importunities than our carelessness. however, we found some of the types of dinosaurs that have since become famous. i joined professor lakes at the morrison quarry in early september of , and helped dig out some of the bones of _atlantosaurus_. a few weeks later i was sent to cañon city to help professor mudge, my old teacher, and mr. felch, who had begun work there in the famous "marsh quarry". it was here that we found the type of _diplodocus_. the hind leg, pelvis and much of the tail of this specimen lay in very orderly arrangement in the sandstone near the edge of the quarry, but the bones were broken into innumerable pieces. after consultation we decided that they were too much broken to be worth saving--and so most of them went over into the dump. sacrilege, doubtless, the modern collector will say, but we did not know much about the modern methods of collecting in those days, and moreover we were in too much of a hurry to get the new discoveries to yale college to take much pains with them. i did observe that the caudal vertebrae had very peculiar chevrons, unlike others that i had seen, and so i attempted to save some samples of them by pasting them up with thick layers of paper. had we only known of plaster-of-paris and burlap the whole specimen might easily have been saved. later, when i reached new haven, i took off the paper and called professor marsh's attention to the strange chevrons. and _diplodocus_ was the result. [illustration: fig. .--the first dinosaur specimen found at bone-cabin quarry. hind limb of _diplodocus_.] my own connection with the discoveries of these old dinosaurs continued only through the following summer, in wyoming, when we added the first mammals from the hills immediately back of the station, and the types of some of the smaller dinosaurs, and when we explored the vicinity for other deposits, on rock creek and in the freeze out mountains. how many tons of these fossils have since been dug up from these deposits in the rocky mountains is beyond computation. my prophecy of hundreds of tons has been fulfilled; and they are preserved in many museums of the world. s.w. williston. the dinosaurs of the bone-cabin quarry.[ ] _by henry fairfield osborn._ one is often asked the questions: "how do you find fossils?" "how do you know where to look for them?" one of the charms of the fossil-hunter's life is the variety, the element of certainty combined with the gambling element of chance. like the prospector for gold, the fossil-hunter may pass suddenly from the extreme of dejection to the extreme of elation. luck comes in a great variety of ways: sometimes as the result of prolonged and deliberate scientific search in a region which is known to be fossiliferous; sometimes in such a prosaic manner as the digging of a well. among discoveries of a highly suggestive, almost romantic kind, perhaps none is more remarkable than the one i shall now describe. _discovery of the great dinosaur quarry._ in central wyoming, at the head of a "draw," or small valley, not far from the medicine bow river, lies the ruin of a small and unique building, which marks the site of the greatest "find" of extinct animals made in a single locality in any part of the world. the fortunate fossil-hunter who stumbled on this site was mr. walter granger of the american museum expedition of . in the spring of , as i approached the hillock on which the ruin stands, i observed, among the beautiful flowers, the blooming cacti, and the dwarf bushes of the desert, what were apparently numbers of dark-brown boulders. on closer examination, it proved that there is really not a single rock, hardly even a pebble, on this hillock; all these apparent boulders are ponderous fossils which have slowly accumulated or washed out on the surface from a great dinosaur bed beneath. a mexican sheep-herder had collected some of these petrified bones for the foundations of his cabin, the first ever built of such strange materials. the excavation of a promising outcrop was almost immediately rewarded by finding a thigh-bone nearly six feet in length which sloped downward into the earth, running into the lower leg and finally into the foot, with all the respective parts lying in the natural position as in life. this proved to be the previously unknown hind limb of the great dinosaur _diplodocus_. in this manner the "bone-cabin quarry" was discovered and christened. the total contents of the quarry are represented in the diagram (not reprinted.) it has given us, by dint of six successive years of hard work, the materials for an almost complete revival of the life of the laramie region as it was in the days of the dinosaurs. by the aid of workmen of every degree of skill, by grace of the accumulated wisdom of the nineteenth century, by the constructive imagination, by the aid of the sculptor and the artist, we can summon these living forms and the living environment from the vasty deep of the past. _the famous como bluffs._ the circumstances leading up to our discovery serve to introduce the story. from to we had been steadily delving into the history of the age of mammals, in deposits dating from two hundred thousand to three million years back, as we rudely estimate geological time. in the course of seven years such substantial progress had been made that i decided to push into the history of the age of reptiles also, and, following the pioneers, marsh and cope, to begin exploration in the period which at once marks the dawn of mammalian life and the climax of the evolution of the great amphibious dinosaurs. in the spring of we accordingly began exploration in the heart of the laramie plains, on the como bluffs. on arrival, we found numbers of massive bones strewn along the base of these bluffs, tumbled from their stratum above, too weather-worn to attract collectors, and serving only to remind one of the time when these animals--the greatest, by far, that nature has ever produced on land--were monarchs of the world. aroused from sleep on a clear evening in camp by the heavy rumble of a passing union pacific freight-train[ ], i shall never forget my meditations on the contrast between the imaginary picture of the great age of dinosaurs, fertile in cycads and in a wonderful variety of reptiles, and the present age of steam, of heavy locomotives toiling through the semi-arid and partly desert laramie plains. so many animals had already been removed from these bluffs that we were not very sanguine of finding more; but after a fortnight our prospecting was rewarded by finding parts of skeletons of the long-limbed dinosaur _diplodocus_ and of the heavy-limbed dinosaur _brontosaurus_. the whole summer was occupied in taking these animals out for shipment to the east, the so-called "plaster method" of removal being applied with the greatest success. briefly, this is a surgical device applied on a large scale for the "setting" of the much-fractured bones of a fossilized skeleton. it consists in setting great blocks of the skeleton, stone and all, in a firm capsule of plaster subsequently reinforced by great splints of wood, firmly drawn together with wet rawhide. the object is to keep all the fragments and splinters of bone together until it can reach the skilful hands of the museum preparator. _the rock waves connecting the bluffs and the quarry._ the como bluffs are about ten miles south of the bone-cabin quarry; between them is a broad stretch of the laramie plains. the exposed bone layer in the two localities is of the same age, and originally was a continuous level stratum which may be designated as the "dinosaur beds;" but this stratum, disturbed and crowded by the uplifting of the not far-distant laramie range of mountains and the freeze out hills, was thrown into a number of great folds or rock waves. large portions, especially of the upfolds, or "anticlines," of the waves, have been subsequently removed by erosion; the edges of these upfolds have been exposed, thus weathering out their fossilized contents, while downfolds are still buried beneath the earth for the explorers of coming centuries. therefore, as one rides across the country to-day from the bluffs to the quarry, startling the intensely modern fauna, the prong-horn antelopes, jack-rabbits, and sage-chickens, he is passing over a vast graveyard which has been profoundly folded and otherwise shaken up and disturbed. sometimes one finds the bone layer removed entirely, sometimes horizontal, sometimes oblique, and again dipping directly into the heart of the earth. this layer (dinosaur beds) is not more than two hundred and seventy-four feet in thickness, and is altogether of fresh-water origin; but as a proof of the oscillations of the earth-level both before and after this great thin sheet of fresh-water rock was so widely spread, there are evidences of the previous invasion of the sea (ichthyosaur beds) and of the subsequent invasion of the sea (mosasaur beds) in the whole rocky mountain region. in traveling through the west, when once one has grasped the idea of continental oscillation, or submergence and emergence of the land, of the sequence of the marine and fresh-water deposits in laying down these pages of earth-history, he will know exactly where to look for this wonderful layer-bed of the giant dinosaurs; he will find that, owing to the uplift of various mountain-ranges, it outcrops along the entire eastern face of the rockies, around the black hills, and in all parts of the laramie plains; it yields dinosaur bones everywhere, but by no means so profusely or so perfectly as in the two famous localities we are describing. _how the skeletons lie in the bluffs and quarry._ at the bluffs single animals lie from twenty to one hundred feet apart; one rarely finds a whole skeleton, such as that of marsh's _brontosaurus excelsus_, the finest specimen ever secured here, which is now one of the treasures of the yale museum. more frequently a half or a third of a skeleton lies together. in the bone-cabin quarry, on the other hand, we came across a veritable noah's-ark deposit, a perfect museum of all the animals of the period. here are the largest of the giant dinosaurs closely mingled with the remains of the smaller but powerful carnivorous dinosaurs which preyed upon them, also those of the slow and heavy-moving armored dinosaurs of the period, as well as of the lightest and most bird-like of the dinosaurs. finely rounded, complete limbs from eight to ten feet in length are found, especially those of the carnivorous dinosaurs, perfect even to the sharply pointed and recurved tips of their toes. other limbs and bones are so crushed and distorted by pressure that it is not worth while removing them. sixteen series of vertebræ were found strung together; among these were eight long strings of tail-bones. the occurrence of these tails is less surprising when we come to study the important and varied functions of the tail in these animals, and the consequent connection of the tail-bones by means of stout tendons and ligaments which held them together for a long period after death. skulls are fragile and rare in the quarry, because in every one of these big skeletons there were no fewer than ninety distinct bones which exceeded the head in size, the excess in most cases being enormous. [illustration: fig. .--collecting dinosaurs at bone-cabin quarry. a. the overlying soil and rocks are loosened with a pick and removed with team and scraper down to the fossil layer. b. the fossil layer is carefully prospected with small tools, chisels, awls and whisk brooms exposing the bones as they lie in the rocks. c. the blocks containing the fossils are channelled around, plastered over top and sides, undercut and carefully turned over and the under side trimmed and plastered. d. the blocks are then packed in boxes or crates with hay or any other available packing material. e. boxes are loaded on wagons and hauled across country to the railroad. f. boxes are finally loaded on cars and shipped through to new york city.] the bluffs appear to represent the region of an ancient shoreline, such conditions as we have depicted in the restoration of _brontosaurus_ (fig. )--the sloping banks of a muddy estuary or of a lagoon, either bare tidal flats or covered with vegetation. evidently the dinosaurs were buried at or near the spot where they perished. the bone-cabin quarry deposit represents entirely different conditions. the theory that it is the accumulation of a flood is, in my opinion, improbable, because a flood would tend to bring entire skeletons down together, distribute them widely, and bury them rapidly. a more likely theory is that this was the area of an old river-bar, which in its shallow waters arrested the more or less decomposed and scattered carcasses which had slowly drifted down-stream toward it, including a great variety of dinosaurs, crocodiles, and turtles, collected from many points up-stream. thus were brought together the animals of a whole region, a fact which vastly enhances the interest of this deposit. _the giant herbivorous dinosaurs._ by far the most imposing of these animals are those which may be popularly designated as the great or giant dinosaurs. the name, derived from _deinos_ terrible, and _sauros_ lizard, refers to the fact that they appeared externally like enormous lizards, with very long limbs, necks, and tails. they were actually remotely related to the tuatera lizard of new zealand, and still more remotely to the true lizards. no land animals have ever approached these giant dinosaurs in size, and naturally the first point of interest is the architecture of the skeleton. the backbone is indeed a marvel. the fitness of the construction consists, like that of the american truss-bridge, in attaining the maximum of strength with the minimum of weight. it is brought about by dispensing with every cubic millimeter of bone which can be spared without weakening the vertebræ for the various stresses and strains to which they were subjected, and these must have been tremendous in an animal from sixty to seventy feet in length. the bodies of the vertebræ are of hour-glass shape, with great lateral and interior cavities; the arches are constructed on the t-iron principle of the modern bridge-builder, the back spines are tubular, the interior is spongy, these devices being employed in great variety, and constituting a mechanical triumph of size, lightness, and strength combined. comparing a great chambered dinosaurian (_camarasaurus_) vertebra (see above) with the weight per cubic inch of an ostrich vertebra, we reach the astonishing conclusion that it weighed only twenty-one pounds, or half the weight of a whale vertebra of the same bulk. the skeleton of a whale seventy-four feet in length has recently been found by mr. f.a. lucas of the brooklyn museum to weigh seventeen thousand nine hundred and twenty pounds. the skeleton of a dinosaur of the same length may be roughly estimated as not exceeding ten thousand pounds. _proofs of rapid movements on land._ lightness of skeleton is a walking or running or flying adaptation, and not at all a swimming one; a swimming animal needs gravity in its skeleton, because sufficient buoyancy in the water is always afforded by the lungs and soft tissues of the body. the extraordinary lightness of these dinosaur vertebræ may therefore be put forward as proof of supreme fitness for the propulsion of an enormous frame during occasional incursions upon land[ ]. there are additional facts which point to land progression, such as the point in the tail where the flexible structure suddenly becomes rigid, as shown in the diagram of vertebræ below; the component joints are so solid and flattened on the lower surface that they seem to demonstrate fitness to support partly the body in a tripodal position like that of a kangaroo. i have therefore hazarded the view that even some of these enormous dinosaurs were capable of raising themselves on their hind limbs, lightly resting on the middle portion of the tail. in such a position the animal would have been capable not only of browsing among the higher branches of trees, but of defending itself against the carnivorous dinosaurs by using its relatively short but heavy front limbs to ward off attacks. there are also indications of aquatic habits in some of the giant dinosaurs which render it probable that a considerable part of their life was led in the water. one of these indications is the backward position of the nostrils. many, but not all, water-living mammals and reptiles have the nostrils on top of the head, in order to breathe more readily when the head is partly immersed. another fact of note, although perhaps less conclusive, is the fitness of the tail for use while moving about in the water, if not in rapid swimming. the great tail, measuring from twenty-eight to thirty feet, was one of the most remarkable structures in these animals, and undoubtedly served a great variety of purposes, propelling while in the water, balancing and supporting and defending while on land. in _diplodocus_ it was most perfectly developed from its muscular base to its delicate and whip-like tip, perhaps for all these functions. _the three kinds of giant dinosaurs._ it is very remarkable that three distinct kinds of these great dinosaurs lived at the same time in the same general region, as proved by the fact that their remains are freely commingled in the quarry. what were the differences in food and habits, in structure and in gait, which prevented that direct and active competition between like types in the struggle for existence which in the course of nature always leads to the extermination of one or the other type? in the last three years we have discovered very considerable differences of structure which make it appear that these animals, while of the same or nearly the same linear dimensions, did not enter into direct competition either for food or for territory. the dinosaur named _diplodocus_ by marsh is the most completely known of the three. our very first discovery in the bone-cabin quarry gave us the hint that _diplodocus_ was distinguished by relatively long, slender limbs, and that it may be popularly known as the "long-limbed dinosaur." the great skeleton found in the como bluffs enabled me to restore for the first time the posterior half of one of these animals estimated as sixty feet in length, the hips and tail especially being in a perfect state of preservation. a larger animal, nearer seventy feet in length, including the anterior half of the body, and still more complete, was discovered about ten miles north of the quarry, and is now in the carnegie museum in pittsburg. combined, these two animals have furnished a complete knowledge of the great bony frame. the head is only two feet long, and is, therefore, small out of all proportion to the great body. the neck measures twenty-one feet four inches, and is by far the longest and largest neck known in any animal living or extinct. the back is relatively very short, measuring ten feet eight inches. the vertebræ of the hip measure two feet and three inches. the tail measures from thirty-two to forty feet. we thus obtain, as a moderate estimate of the total length of the animal, sixty-eight to seventy feet. the restored skeleton, published by mr. j.b. hatcher in july, , and partly embodying our results, gave to science the first really accurate knowledge of the length of these animals, which hitherto had been greatly overestimated. the highest point in the body was above the hips; here in fact, was the center of power and motion, because, as observed above, the tail fairly balanced the anterior part of the body. the restoration by mr. knight is drawn from a very careful model made under my direction, in which the proportions of the animal are precisely estimated. it is, i think, accurate--for a restoration--as well as interesting and up-to-date. these restorations are the "working hypotheses" of our science; they express the present state of our knowledge, and, being subject to modification by future discoveries, are liable to constant change. by contrast, the second type of giant dinosaur, the _brontosaurus_, or "thunder saurian" of marsh, as shown in the restoration (fig. ), was far more massive in structure and relatively shorter in body. five more or less complete skeletons are now to be seen in the yale, american, carnegie, and field columbian museums. in we discovered in the bluffs, about three miles west of the bone-cabin quarry, the largest of these animals which has yet been found; it was worked out with great care and is now being restored and mounted complete in the american museum. the thigh-bone is enormous, measuring five feet eight inches in length, and is relatively of greater mass than that of _diplodocus_. the neck, chest, hips, and tail are correspondingly massive. the neck is relatively shorter, however, measuring eighteen feet, while in _diplodocus_ it measures over twenty-one feet. the total length of this massive specimen is estimated at sixty-three feet, or from six to eight feet less than the largest "long-limbed" dinosaur. the height of the skeleton at the hips is fifteen feet. there is less direct evidence that the "thunder saurian" had the power of raising its fore quarters in the air than in the case of the "light-limbed saurian," because no bend or supporting point in the tail has been distinctly observed. the third type of giant dinosaur is the less completely known "chambered saurian," the _camarasaurus_ of cope or _morosaurus_ of marsh, an animal more quadrupedal in gait or walking more habitually on all fours, like the great _cetiosaurus_, or "whale saurian," discovered near oxford, england. with its shorter tail and heavier fore limbs, it is still less probable that this animal had the power of raising the anterior part of its body from the ground. of a related type, perhaps, is the largest dinosaur ever found; this is the _brachiosaurus_, limb-bones of which were discovered in central colorado in and are now preserved in the field columbian museum of chicago. its thigh-bone is six feet eight inches in length, and its upper arm-bone, or humerus, is even slightly longer. _feeding habits of the giant dinosaurs._ we still have to solve one of the most perplexing problems of fossil physiology; how did the very small head, provided with light jaws, slender and spoon-shaped teeth confined to the anterior region, suffice to provide food for these monsters? i have advanced the idea that the food of _diplodocus_ consisted of some very abundant and nutritious species of water-plant; that the clawed feet were used in uprooting such plants, while the delicate anterior teeth were employed only for drawing them out of the water; that the plants were drawn down the throat in large quantities without mastication, since there were no grinding or back teeth whatever in this animal. unfortunately for this theory, it is now found that the front feet were not provided with many claws, there being only a single claw on the inner side. nevertheless by some such means as this, these enormous animals could have obtained sufficient food in the water to support their great bulk. _the carnivorous dinosaurs._ mingling with the larger bones in the quarry are the more or less perfect remains of swamp turtles, of dwarf crocodiles, of the entirely different group of plated dinosaurs, or _stegosauria_, but especially of two entirely distinct kinds of large and small flesh-eating dinosaurs. the latter rounded out and gave variety to the dinosaur society, and there is no doubt that they served the savage but useful purpose, rendered familiar by the doctrine of malthus, of checking overpopulation. these fierce animals had the same remote ancestry as the giant dinosaurs, but had gradually acquired entirely different habits and appearance. far inferior in size, they were superior in agility, exclusively bipedal, with very long, powerful hind limbs, upon which they advanced by running or springing, and with short fore limbs, the exact uses of which are difficult to ascertain. both hands and feet were provided with powerful tearing claws. on the hind foot is the back claw, so characteristic of the birds, which during the triassic period left its faint impression almost everywhere in the famous connecticut valley imprints of these animals. that the fore limb and hand were of some distinct use is proved by the enormous size of the thumb-claw; while the hand may not have conveyed food to the mouth, it may have served to seize and tear the prey. as to the actual pose in feeding, there can be little doubt as to its general similarity to that of the _raptores_ among the birds, as suggested to me by dr. wortman (see fig. ); one of the hind feet rested on the prey, the other upon the ground, the body being further balanced or supported by the vertebræ of the tail. the animal was thus in a position to apply its teeth and exert all the power of its very powerful arched back in tearing off its food. that the gristle of the bone or cartilage was very palatable is attested not only by the toothmarks upon these bones, but by many similar markings found in the bone-cabin quarry. _the bird-catching dinosaur._ of all the bird-like dinosaurs which have been discovered, none possesses greater similitude to the birds than the gem of the quarry, the little animal about seven feet in length which we have named _ornitholestes_, or the "bird-catching dinosaur." it was a marvel of speed, agility, and delicacy of construction. externally its bones are simple and solid-looking, but as a matter of fact they are mere shells, the walls being hardly thicker than paper, the entire interior of the bone having been removed by the action of the same marvelous law of adaptation which sculptured the vertebræ of its huge contemporaries. there is no evidence, however, that these hollow bones were filled with air from the lungs, as in the case of the bones of birds. the foot is bird-like; the hand is still more so; in fact, no dinosaur hand has ever before been found which so closely mimics that of a bird in the great elongation of the first or index-finger, in the abbreviation of the thumb and middle finger, and in the reduction of the ring-finger. these fingers, with sharp claws, were not strong enough for climbing, and the only special fitness we have been able to imagine is that they were used for the grasping of a light and agile prey (see figs. , .) another reason for the venture of designating this animal as the "bird-catcher" is that the jurassic birds (not thus far discovered in america, but known from the _archæopteryx_ of germany) were not so active or such strong fliers as existing birds; in fact, they were not unlike the little dinosaur itself. they were toothed, long-tailed, short-armed, the body was feathered instead of scaled; they rose slowly from the ground. this renders it probable that they were the prey of the smaller pneumatic-built dinosaurs such as the present animal. this hypothetical bird-catcher seems to have been designed to spring upon a delicately built prey, the structure being the very antipode of that of the large carnivorous dinosaurs. a difficulty in the bird-catching theory, namely, that the teeth are not as sharp as one would expect to find them in a flesh-eater, is somewhat offset by the similarity of the teeth to those of the bird-eating monitor lizards (_varanus_), which are not especially sharp. _the great yield of the quarry._ our explorations in the quarry began in the spring of , and have continued ever since during favorable weather. the total area explored at the close of the sixth year was seven thousand two hundred and fifty square feet. not one of the twelve-foot squares into which the quarry was plotted lacked its covering of bones, and in some cases the bones were two or three deep. each year we have expected to come to the end of this great deposit, but it still yields a large return, although we have reason to believe that we have exhausted the richest portions. we have taken up four hundred and eighty-three parts of animals, some of which may belong to the same individuals. these were packed in two hundred and seventy-five boxes, representing a gross weight of nearly one hundred thousand pounds. reckoning from the number of thigh-bones, we reach, as a rough estimate of the total, seventy-three animals of the following kinds: giant herbivorous dinosaurs, ; plated herbivorous dinosaurs, or stegosaurs, ; iguanodonts or smaller herbivorous dinosaurs, ; large carnivorous dinosaurs, ; small carnivorous dinosaurs, ; crocodiles, ; turtles, . but this represents only a part of the whole deposit, which we know to be of twice the extent already explored, and these figures do not include the bones which were partly washed out and used in the construction of the bone-cabin. the grand total would probably include parts of over one hundred giant dinosaurs. _the struggle for existence among the dinosaurs._ never in the whole history of the world as we now know it have there been such remarkable land scenes as were presented when the reign of these titanic reptiles was at its climax. it was also the prevailing life-picture of england, germany, south america, and india. we can imagine herds of these creatures from fifty to eighty feet in length, with limbs and gait analogous to those of gigantic elephants, but with bodies extending through the long, flexible, and tapering necks into the diminutive heads, and reaching back into the equally long and still more tapering tails. the four or five varieties which existed together were each fitted to some special mode of life; some living more exclusively on land, others for longer periods in the water. the competition for existence was not only with the great carnivorous dinosaurs, but with other kinds of herbivorous dinosaurs (the iguanodonts), which had much smaller bodies to sustain and a much superior tooth mechanism for the taking of food. the cutting off of this giant dinosaur dynasty was nearly if not quite simultaneous the world over. the explanation which is deducible from similar catastrophes to other large types of animals is that a very large frame, with a limited and specialized set of teeth fitted only to a certain special food, is a dangerous combination of characters. such a monster organism is no longer adaptable; any serious change of conditions which would tend to eliminate the special food would also eliminate these great animals as a necessary consequence. [illustration: fig. .--badlands on the red deer river in alberta. this region is the richest known collecting ground for cretacic dinosaurs.] there is an entirely different class of explanations, however, to be considered, which are consistent both with the continued fitness of structure of the giant dinosaurs themselves and with the survival of their especial food; such, for example, as the introduction of a _new enemy_ more deadly even than the great carnivorous dinosaurs. among such theories the most ingenious is that of the late professor cope, who suggested that some of the small, inoffensive, and inconspicuous forms of jurassic mammals, of the size of the shrew and the hedgehog, contracted the habit of seeking out the nests of these dinosaurs, gnawing through the shells of their eggs, and thus destroying the young. the appearance, or evolution, of any egg-destroying animals, whether reptiles or mammals, which could attack this great race at such a defenseless point would be rapidly followed by its extinction. we must accordingly be on the alert for all possible theories of extinction; and these theories themselves will fall under the universal principle of the survival of the fittest until we approximate or actually hit upon the truth. fossil hunting by boat in canada. _by barnum brown._ "how do you know where to look for fossils?" is a common question. in general it may be answered that the surface of north america has been pretty well explored by government surveys and scientific expeditions and the geologic age of the larger areas determined. most important in determining the geologic sequence of the earth's strata are the fossil remains of animal and plant life. a grouping of distinct species of fossils correlated with stratigraphic characters in the rocks determines these subdivisions. when a collection of fossils is desired to represent a certain period, exploring parties are sent to these known areas. sometimes however, chance information leads up to most important discoveries, such as resulted from the work of the past two seasons in alberta, canada. a visitor to the museum, mr. j.l. wagner, while examining our mineral collections saw the large bones in the reptile hall and remarked to the curator of mineralogy that he had seen many similar bones near his ranch in the red deer cañon of alberta. after talking some time an invitation was extended to the writer to visit his home and prospect the cañon. accordingly in the fall of a preliminary trip was made to the locality. from didsbury, a little town north of calgary, the writer drove eastward ninety miles to the red deer river through a portion of the newly opened grain belt of alberta, destined in the near future to produce a large part of the world's bread. near the railroad the land is mostly under cultivation and comfortable homes and bountiful grain fields testify to the rich nature of the soil. a few miles eastward the brushland gives way to a level expanse of grass-covered prairie dotted here and there by large and small lakes probably of glacial origin. mile after mile the road follows section lines and one is rarely out of sight of the house of some "homesteader." it is through this level farm land that the red deer river wends its way flowing through a cañon far below the surface. near wagner's ranch the cañon was prospected and so many bones found that it appeared most desirable to do extended searching along the river. usually fossils are found in "bad lands," where extensive areas are denuded of grass and the surface eroded into hills and ravines. a camp is located near some spring or stream and collectors ride or walk over miles of these exposures in each direction till the region is thoroughly explored. quite different are conditions on the red deer river. cutting through the prairie land the river had formed a cañon two to five hundred feet deep and rarely more than a mile wide at the top. in places the walls are nearly perpendicular and the river winds in its narrow valley, touching one side then crossing to the other so that it is impossible to follow up or down its course any great distance even on horseback. it was evident that the most feasible way to work these banks was from a boat; consequently in the summer of our party proceeded to the town of red deer, where the calgary-edmonton railroad crosses the river. there a flatboat, twelve by thirty feet in dimension, was constructed on lines similar to a western ferry boat, having a carrying capacity of eight tons with a twenty-two foot oar at each end to direct its course. the rapid current averaging about four miles per hour precluded any thought of going up stream in a large boat, so it was constructed on lines sufficiently generous to form a living boat as well as to carry the season's collection of fossils. supplied with a season's provisions, lumber for boxes, and plaster for encasing bones, we began our fossil cruise down a cañon which once echoed songs of the _bois brulé_, for this was at one time the fur territory of the great hudson bay company. [illustration: fig. .--american museum expedition on the red deer river. fossils secured along the banks were packed and loaded aboard the large scow and floated down the river to the railway station.] no more interesting or instructive journey has ever been taken by the writer. high up on the plateau, buildings and haystacks proclaim a well-settled country, but habitations are rarely seen from the river and for miles we floated through picturesque solitude unbroken save by the roar of the rapids. especially characteristic of this cañon are the slides where the current setting against the bank has undermined it until a mountain of earth slips into the river, in some cases almost choking its course. a continual sorting thus goes on, the finer material being carried away while the boulders are left as barriers forming slow moving reaches of calm water and stretches of rapids difficult to navigate during low water. in one of these slides we found several small mammal jaws and teeth not known before from canada, associated with fossil clam shells of eocene age. the long midsummer days in latitude ° gave many working hours, but with frequent stops to prospect the banks we rarely floated more than twenty miles per day. an occasional flock of ducks and geese were disturbed as our boat approached and bank beaver houses were frequently passed, but few of the animals were seen during the daytime. tying the boat to a tree at night we would go ashore to camp among the trees where after dinner pipes were smoked in the glow of a great camp fire. only a fossil hunter or a desert traveler can fully appreciate the luxury of abundant wood and running water. in the stillness of the night the underworld was alive and many little feet rustled the leaves where daylight disclosed no sound. then the beaver and muskrat swam up to investigate this new intruder, while from the tree-tops came the constant query, "who! who!" for seventy miles the country is thickly wooded with pine and poplar, the stately spruce trees silhouetted against the sky adding a charm to the ever changing scene. nature has also been kind to the treeless regions beyond, for underneath the fertile prairie, veins of good lignite coal of varying thickness are successively cut by the river. in many places these are worked in the river banks during winter. one vein of excellent quality is eighteen feet thick, although usually they are much thinner. the government right has been taken to mine most of this coal outcropping along the river. [illustration: fig. .--locality of ankylosaurus skull in edmonton formation in red deer river. the skull is in the rock just above the pick, about the center of the photograph.] along the upper portion of the stream are banks of eocene age, from which shells and mammal jaws were secured, but near the town of content where the river bends southward, a new series of rocks appeared and in these our search was rewarded by finding dinosaur bones similar to those seen at wagner's ranch. specimens were found in increasing numbers as we continued our journey, and progress down the river was necessarily much slower. frequently the boat would be tied up a week or more at one camp while we searched the banks, examining the cliffs layer by layer that no fossil might escape observation. with the little dingey the opposite side of the river was reached so that both sides were covered at the same time from one camp. as soon as a mile or more had been prospected or a new specimen secured, the boat was dropped down to a new convenient anchorage. box after box was added to the collection till scarcely a cubit's space remained unoccupied on board our fossil ark. where prairie badlands are eroded in innumerable buttes and ravines it is always doubtful if one has seen all exposures, so there was peculiar satisfaction in making a thorough search of these river banks knowing that few if any fossils had escaped observation. on account of the heavy rainfall and frequent sliding of banks new fossils are exposed every season so that in a few years these same banks can again be explored profitably. this river will become as classic hunting ground for reptile remains as the badlands of south dakota are for mammals. although the summer days are long in this latitude the season is short and thousands of geese flying southward foretell the early winter. where the temperature is not infrequently forty to sixty degrees below zero in winter, it is difficult to think of a time when a warm climate could have prevailed, yet such condition is indicated by the fossil plants. when the weather became too cold to work with plaster, the fossils were shipped from a branch railroad forty-five miles distant, the camp material was stored for the winter and with block and tackle the big boat was hauled up on shore above the reach of high water. in the summer of the boat was recalked and again launched when we continued our search from the point at which work closed the previous year. during the summer we were visited by the museum's president, prof. henry fairfield osborn, and one of the trustees, mr. madison grant. a canoeing trip, one of great interest and pleasure, was taken with our visitors covering two hundred and fifty miles down the river from the town of red deer, during which valuable material was added to the collection and important geological data secured. as a result of the canadian work the museum is enriched by a magnificent collection of cretaceous fossils some of which are new to science. footnotes: [footnote : transactions kansas academy of science, p. .] [footnote : from fossil wonders of the west. century magazine , vol. lxviii, pp. - . reprinted by permission.] [footnote : at this time the union pacific railroad directly passed the bluffs; in the recent improvement of the grade the main line has been moved to the south.--h.f.o.] [footnote : a different interpretation of this contraction is given upon p. .] references. the published literature on this subject consists chiefly of technical descriptions and researches scattered through the files of numerous scientific journals in europe and america. only the more important titles are cited in this list. i have also listed the recently published text books which give the most authoritative treatment of the dinosaurs, and two or three popular books dealing with fossil vertebrates. students consulting these authorities should remember that great additions to scientific knowledge of dinosaurs have been made during the last two decades, and much of the new evidence is as yet unpublished or undigested. the views and conclusions presented in this handbook are based upon the study of the american museum collections as well as upon the authorities cited below. abel, othenius, . _palaeobiologie der wirbelthiere._ schweitzer-bart'sche verlagsbuchh., stuttgart. branca u. janensch, . _wissenschaftliche ergebnisse der tendaguru expedition._ archiv. f. biontologie, iii bd, i heft. brown, barnum, - . articles in bulletin of amer. mus. nat. hist., descriptive of new cretaceous dinosaurs. chamberlin & salisbury, - . _geology_, vol. i-iii. (henry holt & co. pub.) cope, e.d., - . articles in hayden survey reports, american naturalist, proceedings and transactions of american philosophical society and elsewhere, descriptive of various new or little known dinosaurs. dollo, l., _sauriens de bernissart_, etc. numerous articles chiefly in bulletin museum royale hist. nat. belg. gilmore, c.w., . _osteology of the armored dinosauria in the u.s. national museum with special reference to the genus stegosaurus._ u.s. national museum, bulletin no. , pp. - , pll. i-xxxvii. gilmore, c.w., . _osteology of the jurassic reptile camptosaurus_ etc. proc. u.s. nat. mus., vol. xxxvi, pp. - , pl. vi-xx. hatcher, j.b., . _diplodocus (marsh) its osteology_, etc. memoirs of the carnegie museum, vol. i, pp. - , pll. i-xiii. hatcher, j.b., . _osteology of haplocanthosaurus._ mem. carn. mus., vol. ii, pp. - , pll. i-vi. hatcher, marsh & lull, . _the ceratopsia._ u.s. geol. survey monographs, vol. xlix, pp. i-xxx and - , pll. i-li. hay, o.p., . _bibliography of north american fossil vertebrata._ u.s. geol. sur. bull. no. , pp. - . hennig, e., . _am tendaguru._ holland, w.j., . _osteology of diplodocus._ mem. carn. mus., vol. ii, pp. - , pl. xxiii-xxx. huene, f. von, - . _ueber die dinosaurier der aussereuropäischen trias._ koken's geol. u. pal. abh. n. f., b'd. viii, s. - . huene, f. von, - . _die dinosaurier der europäischen triasformation._ geol. u. pal. abh. supplem. bd. pll. i-cxi. huene, f. von, . _beiträge zur geschichte der archosaurier._ geol. u. pal. abh. n. f., b'd. xiii, pp. - , pll. i-vii. huene, f. von, - . numerous minor contributions in anatom. anzeig. neues jahrb. f. min., geol. centralbl. and other scientific journals. hutchinson, rev. f.n., . _extinct monsters and creatures of other days._ chapman & hall, london. huxley, t.h., - . articles, chiefly in quarterly journal geol. soc. and geol. magazine. discussing the osteology and systematic relationships of various dinosaurs. jaekel, o., - . _ueber die wirbelthiere in den oberen trias von halberstadt._ palæont. zeitschr. b'd. i, s. - , taf. iii-iv. knipe, h.r., . _evolution in the past._ herbert & daniel, london. lambe, lawrence, , with h.f. osborn. see osborn & lambe. lambe, lawrence, - . articles in ottawa naturalist descriptive of new cretacic dinosaurs. lucas, f.a., . _extinct animals._ republished by the american museum, price c. lucas, f.a., . the restoration of extinct animals, smithsonian report for , pp. - , pll. i-viii. lull, r.s., . _fossil footprints of the jura-trias._ mem. boston soc. nat. hist., vol. v, pp. - . lull, r.s., . _dinosaurian distribution._ am. journ. sci., vol. xxix, pp. - ; _the armor of stegosaurus_, ibid., pp. - ; _stegosaurus ungulatus_, ibid., vol. xxx, pp. - . marsh, o.c., - . numerous articles in the american journal of science descriptive of new dinosaurs or announcing results of his studies on these fossils. marsh, o.c., . _the dinosaurs of north america._ u.s. geol. survey, th ann. rep., pt. i, pp. - , pll. i-lxxxv. nopsca, , , . _dinosaurierreste aus siebenburgen (telmatosaurus, etc._). denkschr. math.-naturwiss. kl. kais. akad. wiss. wien, b'd. lxviii, lxxii, lxxiv. nopsca, . _zur kenntniss der genus streptospondylus._ beit. zur pal. oest-ung. bd. xix. nopsca, f., - . various articles on european dinosaurs in geological magazine, bull. soc. geol. norm., etc. osborn, h.f., . _a skeleton of diplodocus_, mem. am. mus. nat. hist., vol. i, pp. - , pll. xxiv-xxviii. osborn, h.f., . _crania of tyrannosaurus and allosaurus; integument of the iguanodont dinosaur trachodon_, mem. am. mus. nat. hist., n. s., vol. i, pp. - , pll. i-x. osborn, h.f., - . articles in american museum bulletin, descriptive of sauropoda, _ornitholestes_, _allosaurus_, _tyrannosaurus_. osborn & lambe, . _vertebrata of the mid-cretaceous of the north-west territory._ can. geol. survey publications quarto series, vol. iii. owen, r., - . monographs on fossil reptilia. palæontographical society, london. riggs, e.s., - . articles on sauropoda in field museum of nat. hist. publications, geology. schuchert, chas., . _palæogeography of north america._ bull. geol. soc. am., vol. xx, pp. - , pll. - . strÖmer von reichenbach, e., . _lehrbuch der palæontologie, ii, wirbelthiere_ (b.g. teubner, leipzig u. berlin.) thÉvenin, a., . _paleontologie de madagascar, iv, dinosaurs._ ann. de paléont, t. ii, pp. - , pll. woodward, a.s., . _vertebrate palæontology._ cambridge science manuals. zittel (broili u. a. rev.) . _grundzuge der palæontologie._ zittel (eastman transl.), . _textbook of palæontology, vol. ii, vertebrata_ (_except mammals_). macmillan & co. * * * * * +--------------------------------------------------------------+ | typographical errors corrected in text: | | | | page : palaeontology replaced with palæontology | | page : familar replaced with familiar | | page : palaeontology not replaced because it quotes | | another book. | | page : pecularity replaced with peculiarity | | page : nust replaced with must | | page : consulation replaced with consultation | | | | | +--------------------------------------------------------------+ my schools and schoolmasters. _morrison and gibb, edinburgh,_ _printers to her majesty's stationery office._ [illustration: hugh miller] my schools and schoolmasters or the story of my education. by hugh miller, author of 'the old red sandstone,' 'footprints of the creator,' etc. etc. [illustration: logo] edinburgh: w. p. nimmo, hay, & mitchell. . contents. chapter i. page a sailor's early career--first marriage--escape from shipwreck--second love--traits of character, chapter ii. childhood and childish visions--a father's death--favourite books--sketch of two maternal uncles, chapter iii. dawn of patriotism--cromarty grammar school--prevalent amusements--old francie--earliest geological researches, chapter iv. uncle sandy as a naturalist--important discovery--cromarty sutors and their caves--expedition to the 'doocot'--difficulties and dangers--sensation produced, chapter v. a would-be patroness--boyish games--first friendship--visit to the highlands--geologizing in the gruids--ossian-worship, chapter vi. cousin george and cousin william--excursion with cousin walter--painful accident--family bereavements--links between the present and the past, chapter vii. subscription school--vacation delights--forays and fears--quarrel with the schoolmaster--poetical revenge--johnstone the forester, chapter viii. choice of a calling--disappointment to relatives--old red sandstone quarry--depression and walking-sleep--temptations of toil--friendship with william ross, chapter ix. life in the bothie--mad bell--mournful history--singular intimacy--manners and customs of north-country masons, chapter x. evening walks--lines on a sun-dial--a haunted stream--insect transformations--jock moghoal--musings, chapter xi. an antiquary in humble life--poor danie--proficiency in porridge-making--depressed health--a good omen--close of apprenticeship, chapter xii. swimming the conon--click-clack the carter--loch maree--fitting up a barrack--highland characteristics, chapter xiii. the brothers fraser--flora of the northern hebrides--diving in the gareloch--sabbaths in flowerdale woods--causes of highland distress, chapter xiv. a cragsman's death--providential escape--property in leith--first sight of edinburgh--peter m'craw--niddry woods--researches among the coal measures, chapter xv. a worthy seceder--the hero of the squad--apology for fanaticism--strikes--recollections of the theatre, chapter xvi. great fires in edinburgh--dr. colquhoun--dr. m'crie--return to the north--stanzas written at sea--geological dreams, chapter xvii. religious phases--true centre of christianity--bearing of geology upon theological belief--delicate health--a gipsy wedding, chapter xviii. convalescence--pursuit of algeology--jock gordon--theory of idiocy--mr. stewart of cromarty, chapter xix. stone-cutting at inverness--a jilted lover--the _osars_--death of uncle james--farewell letter from william ross, chapter xx. publication of poems--newspaper criticisms--walsh the lecturer--enlarged circle of friends--miss dunbar of boath, chapter xxi. arenaceous formations--antiquity of the earth--tremendous hurricane--_loligo vulgare_--researches amid the lias--interesting discoveries, chapter xxii. religious controversies--ecclesiastical dispute--cholera--preventive measures--reform bill, chapter xxiii. visitors in the churchyard--the ladies' walk--first interview--friendship--love--second visit to edinburgh--linlithgow bank--favourable reception of "scenes and legends"--marriage, chapter xxiv. married life at cromarty--ichthyolitic deposit of old red sandstone--correspondence with agassiz and murchison--happy evenings--death of eldest child, chapter xxv. voluntary principle--position of the establishment--letter to lord brougham--invitation to edinburgh--editorship of the _witness_--introduction to dr. chalmers--visit from an old friend--removal to edinburgh, to the reader. it is now nearly a hundred years since goldsmith remarked, in his little educational treatise, that "few subjects have been more frequently written upon than the education of youth." and during the century which has well-nigh elapsed since he said so, there have been so many more additional works given to the world on this fertile topic, that their number has been at least doubled. almost all the men who ever taught a few pupils, with a great many more who never taught any, deem themselves qualified to say something original on education; and perhaps few books of the kind have yet appeared, however mediocre their general tone, in which something worthy of being attended to has not actually been said. and yet, though i have read not a few volumes on the subject, and have dipped into a great many more, i never yet found in them the sort of direction or encouragement which, in working out my own education, i most needed. they insisted much on the various modes of teaching others, but said nothing--or, what amounted to the same thing, nothing to the purpose--on the best mode of teaching one's-self. and as my circumstances and position, at the time when i had most occasion to consult them, were those of by much the largest class of the people of this and every other civilized country--for i was one of the many millions who need to learn, and yet have no one to teach them--i could not help deeming the omission a serious one. i have since come to think, however, that a formal treatise on self-culture might fail to supply the want. curiosity must be awakened ere it can be satisfied; nay, once awakened, it never fails in the end fully to satisfy itself; and it has occurred to me, that by simply laying before the working men of the country the "story of my education," i may succeed in first exciting their curiosity, and next, occasionally at least, in gratifying it also. they will find that by far the best schools i ever attended are schools open to them all--that the best teachers i ever had are (though severe in their discipline) always easy of access--and that the special _form_ at which i was, if i may say so, most successful as a pupil, was a form to which i was drawn by a strong inclination, but at which i had less assistance from my brother men, or even from books, than at any of the others. there are few of the natural sciences which do not lie quite as open to the working men of britain and america as geology did to me. my work, then, if i have not wholly failed in it, may be regarded as a sort of educational treatise, thrown into the narrative form, and addressed more especially to working men. they will find that a considerable portion of the scenes and incidents which it records read their lesson, whether of encouragement or warning, or throw their occasional lights on peculiarities of character or curious natural phenomena, to which their attention might be not unprofitably directed. should it be found to possess an interest to any other class, it will be an interest chiefly derivable from the glimpses which it furnishes of the inner life of the scottish people, and its bearing on what has been somewhat clumsily termed "the condition-of-the-country question." my sketches will, i trust, be recognised as true to fact and nature. and as i have never perused the autobiography of a working man of the more observant type, without being indebted to it for new facts and ideas respecting the circumstances and character of some portion of the people with which i had been less perfectly acquainted before, i can hope that, regarded simply as the memoir of a protracted journey through _districts_ of society not yet very sedulously explored, and scenes which few readers have had an opportunity of observing for themselves, my story may be found to possess some of the interest which attaches to the narratives of travellers who see what is not often seen, and know, in consequence, what is not generally known. in a work cast into the autobiographic form, the writer has always much to apologize for. with himself for his subject, he usually tells not only more than he ought, but also, in not a few instances, more than he intends. for, as has been well remarked, whatever may be the character which a writer of his own memoirs is desirous of assuming, he rarely fails to betray the real one. he has almost always his unintentional revelations, that exhibit peculiarities of which he is not conscious, and weaknesses which he has failed to recognise as such; and it will no doubt be seen that what is so generally done in works similar to mine, i have not escaped doing. but i cast myself full on the good-nature of the reader. my aims have, i trust, been honest ones; and should i in any degree succeed in rousing the humbler classes to the important work of self-culture and self-government, and in convincing the higher that there are instances in which working men have at least as legitimate a claim to their respect as to their pity, i shall not deem the ordinary penalties of the autobiographer a price too high for the accomplishment of ends so important. my schools and schoolmasters or the story of my education. chapter i. "ye gentlemen of england, who live at home at ease, oh, little do ye think upon the dangers of the seas."--old song. rather more than eighty years ago, a stout little boy, in his sixth or seventh year, was despatched from an old-fashioned farm-house in the upper part of the parish of cromarty, to drown a litter of puppies in an adjacent pond. the commission seemed to be not in the least congenial. he sat down beside the pool, and began to cry over his charge; and finally, after wasting much time in a paroxysm of indecision and sorrow, instead of committing the puppies to the water, he tucked them up in his little kilt, and set out by a blind pathway which went winding through the stunted heath of the dreary maolbuoy common, in a direction opposite to that of the farm-house--his home for the two previous twelvemonths. after some doubtful wandering on the waste, he succeeded in reaching, before nightfall, the neighbouring seaport town, and presented himself, laden with his charge, at his mother's door. the poor woman--a sailor's widow, in very humble circumstances--raised her hands in astonishment: "oh, my unlucky boy," she exclaimed, "what's this?--what brings you here?" "the little doggies, mither," said the boy; "i couldna drown the little doggies; and i took them to you." what afterwards befell the "little doggies," i know not; but trivial as the incident may seem, it exercised a marked influence on the circumstances and destiny of at least two generations of creatures higher in the scale than themselves. the boy, as he stubbornly refused to return to the farm-house, had to be sent on shipboard, agreeably to his wish, as a cabin-boy; and the writer of these chapters was born, in consequence, a sailor's son, and was rendered, as early as his fifth year, mainly dependent for his support on the sedulously plied but indifferently remunerated labours of his only surviving parent, at the time a sailor's widow. the little boy of the farm-house we a descended from a long line of seafaring men,--skilful and adventurous sailors,--some of whom had coasted along the scottish shores as early as the times of sir andrew wood and the "bold bartons," and mayhap helped to man that "verrie monstrous schippe the great michael," that "cumbered all scotland to get her to sea." they had taken as naturally to the water as the newfoundland dog or the duckling. that waste of life which is always so great in the naval profession had been more than usually so in the generation just passed away. of the boy's two uncles, one had sailed round the world with anson, and assisted in burning paita, and in boarding the manilla galleon; but on reaching the english coast he mysteriously disappeared, and was never more heard of. the other uncle, a remarkably handsome and powerful man,--or, to borrow the homely but not inexpressive language in which i have heard him described, "as _pretty_ a fellow as ever stepped in shoe-leather,"--perished at sea in a storm; and several years after, the boy's father, when entering the firth of cromarty, was struck overboard, during a sudden gust, by the boom of his vessel, and, apparently stunned by the blow, never rose again. shortly after, in the hope of screening her son from what seemed to be the hereditary fate, his mother had committed the boy to the charge of a sister, married to a farmer of the parish, and now the mistress of the farm-house of ardavell; but the family death was not to be so avoided; and the arrangement terminated, as has been seen, in the transaction beside the pond. in course of time the sailor boy, despite of hardship and rough usage, grew up into a singularly robust and active man, not above the middle size,--for his height never exceeded five feet eight inches,--but broad-shouldered, deep-chested, strong-limbed, and so compact of bone and muscle, that in a ship of the line, in which he afterwards sailed, there was not, among five hundred able-bodied seamen, a man who could lift so great a weight, or grapple with him on equal terms. his education had been but indifferently cared for at home: he had, however, been taught to read by a female cousin, a niece of his mother's, who, like her too, was both the daughter and the widow of a sailor; and for his cousin's only child, a girl somewhat younger than himself, he had contracted a boyish affection, which in a stronger form continued to retain possession of him after he grew up. in the leisure thrown on his-hands in long indian and chinese voyages, he learned to write; and profited so much by the instructions of a comrade, an intelligent and warm-hearted though reckless irishman, that he became skilful enough to keep a log-book, and to take a reckoning with the necessary correctness,--accomplishments far from common at the time among ordinary sailors. he formed, too, a taste for reading. the recollection of his cousin's daughter may have influenced him, but he commenced life with a determination to rise in it,--made his first money by storing up instead of drinking his grog,--and, as was common in those times, drove a little trade with the natives of foreign parts in articles of curiosity and vertu, for which, i suspect, the custom-house dues were not always paid. with all his scotch prudence, however, and with much kindliness of heart and placidity of temper there was some wild blood in his veins, derived, mayhap, from one or two buccaneering ancestors, that, when excited beyond the endurance point, became sufficiently formidable; and which, on at least one occasion, interfered very considerably with his plans and prospects. on a protracted and tedious voyage in a large east indiaman, he had, with the rest of the crew, been subjected to harsh usage by a stern, capricious captain; but, secure of relief on reaching port, he had borne uncomplainingly with it all. his comrade and quondam teacher, the irishman, was, however, less patient; and for remonstrating with the tyrant, as one of a deputation of the seamen, in what was deemed a mutinous spirit, he was laid hold of, and was in the course of being ironed down to the deck under a tropical sun, when his quieter comrade, with his blood now heated to the boiling point, stepped aft, and with apparent calmness re-stated the grievance. the captain drew a loaded pistol from his belt; the sailor struck up his hand; and, as the bullet whistled through the rigging above, he grappled with him, and disarmed him in a trice. the crew rose, and in a few minutes the ship was all their own. but having failed to calculate on such a result, they knew not what to do with their charge; and, acting under the advice of their new leader, who felt to the full the embarrassing nature of the position, they were content simply to demand the redress of their grievances as their terms of surrender; when, untowardly for their claims, a ship of war hove in sight, much in want of men, and, bearing down on the indiaman, the mutiny was at once suppressed, and the leading mutineers sent aboard the armed vessel, accompanied by a grave charge, and the worst possible of characters. luckily for them, however, and especially luckily for the irishman and his friend, the war-ship was so weakened by scurvy, at that time the untamed pest of the navy, that scarce two dozen of her crew could do duty aloft a fierce tropical tempest, too, which broke out not long after, pleaded powerfully in their favour; and the affair terminated in the ultimate promotion of the irishman to the office of ship-schoolmaster, and of his scotch comrade to the captaincy of the foretop. my narrative abides with the latter. he remained for several years aboard a man-of-war, and, though not much in love with the service, did his duty in both storm and battle. he served in the action off the dogger-bank,--one of the last naval engagements fought ere the manoeuvre of breaking the line gave to british valour its due superiority, by rendering all our great sea-battles decisive; and a comrade who sailed in the same vessel, and from whom, when a boy, i have received kindness for my father's sake, has told me that, their ship being but indifferently manned at the time, and the extraordinary personal strength and activity of his friend well known, he had a station assigned him at his gun against two of the crew, and that during the action he actually outwrought them both. at length, however, the enemy drifted to leeward to refit; and when set to repair the gashed and severed rigging, such was his state of exhaustion, in consequence of the previous overstrain on every nerve and muscle, that he had scarce vigour enough left to raise the marlingspike employed in the work to the level of his face. suddenly, when in this condition, a signal passed along the line, that the dutch fleet, already refitted, was bearing down to renew the engagement. a thrill like that of an electric shock passed through the frame of the exhausted sailor; his fatigue at once left him; and, vigorous and strong as when the action first began, he found himself able, as before, to run out against his two comrades the one side of a four-and-twenty pounder. the instance is a curious one of the influence of that "spirit" which, according to the wise king, enables a man to "sustain his infirmity." it may be well not to inquire too curiously regarding the mode in which this effective sailor quitted the navy. the country had borrowed his services without consulting his will; and he, i suspect, reclaimed them on his own behalf without first asking leave. i have been told by my mother that he found the navy very intolerable;--the mutiny at the nore had not yet meliorated the service to the common sailor. among other hardships, he had been oftener than once under not only very harsh, but also very incompetent officers; and on one occasion, after toiling on the foreyard in a violent night-squall, with some of the best seamen aboard, in fruitless attempts to furl up the sail, he had to descend, cap in hand, at the risk of a flogging, and humbly implore the boy-lieutenant in charge that he should order the vessel's head to be laid in a certain direction. luckily for him, the advice was taken by the young gentleman, and in a few minutes the sail was furled. he left his ship one fine morning, attired in his best, and having on his head a three-cornered hat, with tufts of lace at the corners, which i well remember, from the circumstance that it had long after to perform an important part in certain boyish masquerades at christmas and the new year; and as he had taken effective precautions for being reported missing in the evening, he got clear off. of some of the after-events of his life i retain such mere fragmentary recollections, dissociated from date and locality, as might be most readily seized on by the imagination of a child. at one time, when engaged in one of his indian voyages, he was stationed during the night, accompanied by but a single comrade, in a small open boat, near one of the minor mouths of the ganges; and he had just fallen asleep on the beams, when he was suddenly awakened by a violent motion, as if his skiff were capsizing. starting up, he saw in the imperfect light a huge tiger, that had swam, apparently, from the neighbouring jungle, in the act of boarding the boat. so much was he taken aback, that though a loaded musket lay beside him, it was one of the loose beams, or _foot-spars_, used as fulcrums for the feet in rowing, that he laid hold of as a weapon; but such was the blow he dealt to the paws of the creature, as they rested on the gunwale, that it dropped off with a tremendous snarl, and he saw it no more. on another occasion, he was one of three men sent with despatches to some indian port in a boat, which, oversetting in the open sea in a squall, left them for the greater part of three days only its upturned bottom for their resting-place. and so thickly during that time did the sharks congregate around them, that though a keg of rum, part of the boat's stores, floated for the first two days within a few yards of them, and they had neither meat nor drink, none of them, though they all swam well, dared attempt regaining it. they were at length relieved by a spanish vessel, and treated with such kindness, that the subject of my narrative used ever after to speak well of the spaniards, as a generous people, destined ultimately to rise. he was at one time so reduced by scurvy, in a vessel half of whose crew had been carried off by the disease, that, though still able to do duty on the tops, the pressure of his finger left for several seconds a dent in his thigh, as if the muscular flesh had become of the consistency of dough. at another time, when overtaken in a small vessel by a protracted tempest, in which "for many days neither sun nor moon appeared," he continued to retain his hold of the helm for twelve hours after every other man aboard was utterly prostrated and down, and succeeded, in consequence, in weathering the storm for them all. and after his death, a nephew of my mother's, a young man who had served his apprenticeship under him, was treated with great kindness on the spanish main, for his sake, by a west indian captain, whose ship and crew he had saved, as the captain told the lad, by boarding them in a storm, at imminent risk to himself, and working their vessel into port, when, in circumstances of similar exhaustion, they were drifting full upon an iron-bound shore. many of my other recollections of this manly sailor are equally fragmentary in their character; but there is a distinct bit of picture in them all, that strongly impressed the boyish fancy. when not much turned of thirty, the sailor returned to his native town, with money enough, hardly earned, and carefully kept, to buy a fine large sloop, with which he engaged in the coasting trade; and shortly after he married his cousin's daughter. he found his cousin, who had supported herself in her widowhood by teaching a school, residing in a dingy, old-fashioned house, three rooms in length, but with the windows of its second story half-buried in the eaves, that had been left her by their mutual grandfather, old john feddes, one of the last of the buccaneers. it had been built, i have every reason to believe, with spanish gold; not, however, with a great deal of it, for, notwithstanding its six rooms, it was a rather humble erection, and had now fallen greatly into disrepair. it was fitted up with some of the sailor's money, and, after his marriage, became his home,--a home rendered all the happier by the presence of his cousin, now rising in years, and who, during her long widowhood, had sought and found consolation, amid her troubles and privations, where it was surest to be found. she was a meek-spirited, sincerely pious woman; and the sailor, during his more distant voyages,--for he sometimes traded with ports of the baltic on the one hand, and with those of ireland and the south of england on the other,--had the comfort of knowing that his wife, who had fallen into a state of health chronically delicate, was sedulously tended and cared for by a devoted mother. the happiness which he would have otherwise enjoyed was, however, marred in some degree by his wife's great delicacy of constitution, and ultimately blighted by two unhappy accidents. he had not lost the nature which had been evinced at an early age beside the pond: for a man who had often looked death in the face, he had remained nicely tender of human life, and had often hazarded his own in preserving that of others; and when accompanied, on one occasion, by his wife and her mother to his vessel, just previous to sailing, he had unfortunately to exert himself in her presence, in behalf of one of his seamen, in a way that gave her constitution a shock from which it never recovered. a clear frosty moonlight evening had set in; the pier-head was glistening with new-formed ice; and one of the sailors, when engaged in casting over a haulser which he had just loosed, missed footing on the treacherous margin, and fell into the sea. the master knew his man could not swim; a powerful seaward tide sweeps past the place with the first hours of ebb; there was not a moment to be lost; and, hastily throwing off his heavy greatcoat, he plunged after him, and in an instant the strong current swept them both out of sight. he succeeded, however, in laying hold of the half-drowned man, and, striking with him from out the perilous tideway into an eddy, with a herculean effort he regained the quay. on reaching it, his wife lay insensible in the arms of her mother; and as she was at the time in the delicate condition incidental to married women, the natural consequence followed, and she never recovered the shock, but lingered for more than a twelve-mouth, the mere shadow of her former self; when a second event, as untoward as the first, too violently shook the fast ebbing sands, and precipitated her dissolution. a prolonged tempest from the stormy north-east had swept the moray firth of its shipping, and congregated the stormbound vessels by scores in the noble harbour of cromarty, when the wind chopped suddenly round, and they all set out to sea,--the sloop of the master among the rest. the other vessels kept the open firth; but the master, thoroughly acquainted with its navigation, and in the belief that the change of wind was but temporary, went on hugging the land on the weather side, till, as he had anticipated, the breeze set full into the old quarter, and increased into a gale. and then, when all the rest of the fleet had no other choice left them than just to scud back again, he struck out into the firth in a long tack, and, doubling kinnaird's head and the dreaded buchan ness, succeeded in making good his voyage south. next morning the wind-bound vessels were crowding the harbour of refuge as before, and only his sloop was amissing. the first war of the french revolution had broken out at the time; it was known there were several french privateers hovering on the coast; and the report went abroad that the missing sloop had been captured by the french. there was a weather-brained tailor in the neighbourhood, who used to do very odd things, especially, it was said, when the moon was at the full, and whom the writer remembers from the circumstance that he fabricated for him his first jacket, and that, though he succeeded in sewing on one sleeve to the hole at the shoulder, where it ought to be, he committed the slight mistake of sewing on the other sleeve to one of the pocket-holes. poor andrew fern had heard that his townsman's sloop had been captured by a privateer, and, fidgety with impatience till he had communicated the intelligence where he thought it would tell most effectively, he called on the master's wife, to ask whether she had not heard that all the wind-bound vessels had got back again save the master's, and to wonder no one had yet told her that, if _his_ had not got back, it was simply because it had been taken by the french. the tailor's communication told more powerfully than he could have anticipated: in less than a week after, the master's wife was dead; and long ere her husband's return she was lying in the quiet family burying-place, in which--so heavy were the drafts made by accident and violent death on the family--the remains of none of the male members had been deposited for more than a hundred years. the mother, now left, by the death of her daughter, to a dreary solitude, sought to relieve its tedium, during the absence of her son-in-law when on his frequent voyages, by keeping, as she had done ere his return from foreign parts, a humble school. it was attended by two little girls, the children of a distant relation but very dear friend, the wife of a tradesman of the place,--a woman, like herself, of sincere though unpretending piety. their similarity of character in this respect could hardly be traced to their common ancestor. he was the last curate of the neighbouring parish of nigg; and, though not one of those intolerant episcopalian ministers that succeeded in rendering their church thoroughly hateful to the scottish people,--for he was a simple, easy man, of much good nature,--he was, if tradition speak true, as little religious as any of them. in one of the earlier replies to that curious work, "scotch presbyterian eloquence displayed," i find a nonsensical passage from one of the curate's sermons, given as a set-off against the presbyterian nonsense adduced by the other side. "mr. james m'kenzie, curate of nigg in ross," says the writer, "describing eternity to his parishioners, told them that in that state they would be immortalized, so that nothing could hurt them: a slash of a broadsword could not hurt you, saith he; nay, a cannon-ball would play but _baff_ on you." most of the curate's descendants were stanch presbyterians, and animated by a greatly stronger spirit than his; and there were none of them stancher in their presbyterianism than the two elderly women who counted kin from him in the fourth degree, and who, on the basis of a common faith, had become attached friends. the little girls were great favourites with the schoolmistress; and when, as she rose in years, her health began to fail, the elder of the two removed from her mother's house, to live with, and take care of her; and the younger, who was now shooting up into a pretty young woman, used, as before, to pass much of her time with her sister and her old mistress. meanwhile the shipmaster was thriving. he purchased a site for a house beside that of his buccaneering grandfather, and built for himself and his aged relative a respectable dwelling, which cost him about four hundred pounds, and entitled his son, the writer, to exercise the franchise, on the passing, considerably more than thirty years after, of the reform bill. the new house was, however, never to be inhabited by its builder; for, ere it was fully finished, he was overtaken by a sad calamity, that, to a man of less energy and determination, would have been ruin, and in consequence of which he had to content himself with the old house as before, and almost to begin the world anew. i have now reached a point in my narrative at which, from my connexion with the two little girls,--both of whom still live in the somewhat altered character of women far advanced in life,--i can be as minute in its details as i please; and the details of the misadventure which stripped the shipmaster of the earnings of long years of carefulness and toil, blended as they are with what an old critic might term a curious _machinery_ of the supernatural, seem not unworthy of being given unabridged. early in november , two vessels--the one a smack in the london and inverness trade, the other the master's square-rigged sloop--lay wind-bound for a few days on their passage north, in the port of peterhead. the weather, which had been stormy and unsettled, moderated towards the evening of the fifth day of their detention; and the wind chopping suddenly into the east, both vessels loosed from their moorings, and, as a rather gloomy day was passing into still gloomier night, they bore out to sea. the breeze soon freshened into a gale; the gale swelled into a hurricane, accompanied by a thick snow-storm: and when, early next morning, the smack opened the firth, she was staggering under her storm-jib, and a mainsail reefed to the cross. whatever wind may blow, there is always shelter within the sutors; and she was soon riding at anchor in the roadstead; but she had entered the bay alone; and when day broke, and for a brief interval the driving snow-rack cleared up towards the east, no second sail appeared in the offing. "poor miller!" exclaimed the master of the smack; "if he does not enter the firth ere an hour, he will never enter it at all. good sound vessel, and better sailor never stepped between stem and stern; but last night has, i fear, been too much for him. he should have been here long ere now." the hour passed; the day itself wore heavily away in gloom and tempest; and as not only the master, but also all the crew of the sloop, were natives of the place, groups of the town's-folk might be seen, so long as the daylight lasted, looking out into the storm from the salient points of the old coast-line that, rising immediately behind the houses, commands the firth. but the sloop came not, and before they had retired to their homes, a second night had fallen, dark and tempestuous as the first. ere morning the weather moderated: a keen frost bound up the wind in its icy fetters; and during the following day, though a heavy swell continued to roll shorewards between the sutors, and sent up its white foam high against the cliffs, the surface of the sea had become glassy and smooth. but the day wore on, and evening again fell; and even the most sanguine relinquished all hope of ever again seeing the sloop or her crew. there was grief in the master's dwelling,--grief in no degree the less poignant from the circumstance that it was the tearless, uncomplaining grief of rigid old age. her two youthful friends and their mother watched with the widow, now, as it seemed, left alone in the world. the town-clock had struck the hour of midnight, and still she remained as if fixed to her seat, absorbed in silent, stupifying sorrow, when a heavy foot was heard pacing along the now silent street. it passed, and anon returned; ceased for a moment nearly opposite the window; then approached the door, where there was a second pause; and then there succeeded a faltering knock, that struck on the very hearts of the inmates within. one of the girls sprang up, and on undoing the bolt, shrieked out, as the door fell open, "o mistress, here is jack grant the mate!" jack, a tall, powerful seaman, but apparently in a state of utter exhaustion, staggered, rather than walked in, and flung himself into a chair. "jack," exclaimed the old woman, seizing him convulsively by both his hands, "where's my cousin?--where's hugh?" "the master's safe and well," said jack; "but the poor _friendship_ lies in _spales_ on the bar of findhorn." "god be praised!" ejaculated the widow. "let the gear go!" i have often heard jack's story related in jack's own words, at a period of life when repetition never tires; but i am not sure that i can do it the necessary justice now. "we left peterhead," he said, "with about half a cargo of coal,--for we had lightened ship a day or two before,--and the gale freshened as the night came on. we made all tight, however; and though the snow-drift was so blinding in the thick of the shower that i could scarce see my hand before me, and though it soon began to blow great guns, we had given the land a good offing, and the hurricane blew the right way. just as we were loosening from the quay, a poor young woman, much knocked up, with a child in her arms, had come to the vessel's side, and begged hard of master to take her aboard. she was a soldier's wife, and was travelling to join her husband at fort-george; but she was already worn out and penniless, she said; and now, as a snow-storm threatened to block up the roads, she could neither stay where she was, nor pursue her journey. her infant, too,--she was sure, if she tried to force her way through the hills, it would perish in the snow. the master, though unwilling to cumber us with a passenger in such weather, was induced, out of pity for the poor destitute creature, to take her aboard. and she was now with her child, all alone, below in the cabin i was stationed a-head on the out-look beside the foresail _horse_: the night had grown pitch dark; and the lamp in the binnacle threw just light enough through the grey of the shower to show me the master at the helm. he looked more anxious, i thought, than i had almost ever seen him before, though i have been with him, mistress, in bad weather; and all at once i saw he had got company, and strange company too, for such a night: there was a woman moving round him, with a child in her arms. i could see her as distinctly as ever i saw anything,--now on the one side, now on the other,--at one time full in the light, at another half lost in the darkness. that, i said to myself, must be the soldier's wife and her child; but how in the name of wonder can the master allow a woman to come on deck in such a night as this, when we ourselves have just enough ado to keep footing? he takes no notice of her neither, but keeps looking on, quite in his wont, at the binnacle. 'master,' i said, stepping up to him, 'the woman had surely better go below.' 'what woman, jack?' said he; 'our passenger, you may be sure, is nowhere else.' i looked round, mistress, and found he was quite alone, and that the companion-head was hasped down. there came a cold sweat all over me. 'jack,' said the master, 'the night is getting worse, and the roll of the waves heightening every moment. i'm convinced, too, our cargo is shifting: as the last sea struck us, i could hear the coals rattle below; and see how stiffly we heel to the larboard. say nothing, however, to the men, but have all your wits about you; and look, meanwhile, to the boat-tackle and the oars. i have seen a boat live in as bad a night as this.' as he spoke, a blue light from above glimmered on the deck. we looked up, and saw a dead-fire sticking to the cross-trees. 'it's all over with us now, master,' said i. 'nay, man,' replied the master, in his easy, humorous way, which i always like well enough except in bad weather, and then i see his humour is served out like his extra grog, to keep up hearts that have cause enough to get low,--'nay, man,' he said, 'we can't afford to let your grandmother board us to-night. if you will insure _me_ against the shifting coal, i'll be your guarantee against the dead-light. why, it's as much a natural appearance, man, as a flash of lightning. away to your berth, and keep up a good heart: we can't be far from covesea now, where, when once past the skerries, the swell will take off; and then, in two short hours, we may be snug within the sutors.' i had scarcely reached my berth a-head, mistress, when a heavy sea struck us on the starboard quarter, almost throwing us on our beam-ends. i could hear the rushing of the coals below, as they settled on the larboard side; and though the master set us full before the wind, and gave instant orders to lighten every stitch of sail,--and it was but little sail we had at the time to lighten,--still the vessel did not rise, but lay unmanageable as a log, with her gunwale in the water. on we drifted, however, along the south coast, with little expectation save that every sea would send us to the bottom; until, in the first grey of the morning, we found ourselves among the breakers of the terrible bar of findhorn. and shortly after, the poor _friendship_ took the ground right on the edge of the quicksands, for she would neither stay nor wear; and as she beat hard against the bottom, the surf came rolling over half-mast high. "just as we struck," continued jack, "the master made a desperate effort to get into the cabin. the vessel couldn't miss, we saw, to break up and fill; and though there was little hope of any of us ever setting foot ashore, he wished to give the poor woman below a chance with the rest. all of us but himself, mistress, had got up into the shrouds, and so we could see round us a bit; and he had just laid his hand on the companion-hasp to undo the door, when i saw a tremendous sea coming rolling towards us, like a moving wall, and shouted on him to hold fast. he sprang to the weather back-stay, and laid hold. the sea came tumbling on, and, breaking full twenty feet over his head, buried him for a minute's space in the foam. we thought we should never see him more; but when it cleared away, there was he still, with his iron grip on the stay, though the fearful wave had water-logged the _friendship_ from bow to stem, and swept her companion-head as cleanly off by the deck as if it had been cut with a saw. no human aid could avail the poor woman and her baby. master could hear the terrible choking noise of her dying agony right under his feet, with but a two-inch plank between; and the sounds have haunted him ever since. but even had he succeeded in getting her on deck, she could not possibly have survived, mistress. for five long hours we clung to the rigging, with the seas riding over us all the time like wild horses; and though we could see, through the snow-drift and the spray, crowds on the shore, and boats lying thick beside the pier, none dared venture out to assist us, till near the close of the day, when the wind fell with the falling tide, and we were brought ashore, more dead than alive, by a volunteer crew from the harbour. the unlucky _friendship_ began to break up under us ere mid-day, and we saw the corpse of the drowned woman, with the dead infant still in its arms, come floating out through a hole in the side. but the surf soon tore mother and child asunder, and we lost sight of them as they drifted away to the west. master would have crossed the firth himself this morning to relieve your mind, but being less worn out than any of us, he thought it best to remain in charge of the wreck." such, in effect, was the narrative of jack grant, the mate. the master, as i have said, had well-nigh to commence the world anew, and was on the eve of selling his new house at a disadvantage, in order to make up the sum necessary for providing himself with a new vessel, when a friend interposed, and advanced him the balance required. he was assisted, too, by a sister in leith, who was in tolerably comfortable circumstances; and so he got a new sloop, which, though not quite equal in size to the one he had lost, was built wholly of oak, every plank and beam of which he had superintended in the laying down, and a prime sailer to boot; and so, though he had to satisfy himself with the accommodation of the old domicile, with its little rooms and its small windows, and to let the other house to a tenant, he began to thrive again as before. meanwhile his aged cousin was gradually sinking. the master was absent on one of his longer voyages, and she too truly felt that she could not survive till his return. she called to her bedside her two young friends, the sisters, who had been unwearied in their attentions to her, and poured out her blessing on them; first on the elder, and then on the younger. "but as for you, harriet," she added, addressing the latter, "there waits for you one of the best blessings of this world also--the blessings of a good husband: you will be a gainer in the end, even in this life, through your kindness to the poor childless widow." the prophecy was a true one: the old woman had shrewdly marked where the eyes of her cousin had been falling of late; and in about a twelvemonth after her death her young friend and pupil had become the master's wife. there was a very considerable disparity between their ages,--the master was forty-four, and his wife only eighteen,--but never was there a happier marriage. the young wife was simple, confiding, and affectionate; and the master of a soft and genial nature, with a large amount of buoyant humour about him, and so equable of temper, that, during six years of wedded life, his wife never saw him angry but once. i have heard her speak of the exceptional instance, however, as too terrible to be readily forgotten. she had accompanied him on ship-board, during their first year of married life, to the upper parts of the cromarty firth, where his sloop was taking in a cargo of grain, and lay quietly embayed within two hundred yards of the southern shore. his mate had gone away for the night to the opposite side of the bay, to visit his parents, who resided in that neighbourhood; and the remaining crew consisted of but two seamen, both young and somewhat reckless men, and the ship-boy. taking the boy with them to keep the ship's boat afloat, and wait their return, the two sailors went ashore, and, setting out for a distant public-house, remained there drinking till a late hour. there was a bright moon overhead, but the evening was chilly and frosty; and the boy, cold, tired, and half-overcome by sleep, after waiting on till past midnight, shoved off the boat, and, making his way to the vessel, got straightway into his hammock and fell asleep. shortly after, the two men came to the shore much the worse of liquor; and, failing to make themselves heard by the boy, they stripped off their clothes, and chilly as the night was, swam aboard. the master and his wife had been for hours snug in their bed, when they were awakened by the screams of the boy: the drunken men were unmercifully bastinading him with a rope's end apiece. the master, hastily rising, had to interfere in his behalf, and with the air of a man who knew that remonstrance in the circumstances would be of little avail, he sent them both off to their hammocks. scarcely, however, had he again got into bed, when he was a second time aroused by the cries of the boy, uttered on this occasion in the shrill tones of agony and terror; and, promptly springing up, now followed by his wife, he found the two sailors again belabouring the boy, and that one of them, in his blind fury, had laid hold of a rope-end, armed, as is common on shipboard, with an iron thimble or ring, and that every blow produced a wound. the poor boy was streaming over with blood. the master, in the extremity of his indignation, lost command of himself. rushing in, the two men were in a moment dashed against the deck;--they seemed powerless in his hands as children; and had not his wife, although very unfit at the time for mingling in a fray, run in and laid hold of him,--a movement which calmed him at once,--it was her serious impression that, unarmed as he was, he would have killed them both upon the spot. there are, i believe, few things more formidable than the unwonted anger of a good-natured man. chapter ii. "three stormy nights and stormy days we tossed upon the raging main; and long we strove our barque to save, but all our striving was in vain."--lowe. i was born, the first child of this marriage, on the th day of october , in the low, long house built by my great-grandfather the buccaneer. my memory awoke early. i have recollections which date several months ere the completion of my third year; but, like those of the golden age of the world, they are chiefly of a mythologic character. i remember, for instance, getting out unobserved one day to my father's little garden, and seeing there a minute duckling covered with soft yellow hair, growing out of the soil by its feet, and beside it a plant that bore as its flowers a crop of little mussel shells of a deep red colour. i know not what prodigy of the vegetable kingdom produced the little duckling; but the plant with the shells must, i think, have been a scarlet runner, and the shells themselves the papilionaceous blossoms. i have a distinct recollection, too,--but it belongs to a later period,--of seeing my ancestor, old john feddes the buccaneer, though he must have been dead at the time considerably more than half a century. i had learned to take an interest in his story, as preserved and told in the antique dwelling which he had built more than a hundred years before. to forget a love disappointment, he had set out early in life for the spanish main, where, after giving and receiving some hard blows, he succeeded in filling a little bag with dollars and doubloons; and then coming home, he found his old sweetheart a widow, and so much inclined to listen to reason, that she ultimately became his wife. there were some little circumstances in his history which must have laid hold of my imagination; for i used over and over to demand its repetition; and one of my first attempts at a work of art was to scrabble his initials with my fingers, in red paint, on the house-door. one day, when playing all alone at the stair-foot--for the inmates of the house had gone out--something extraordinary had caught my eye on the landing-place above; and looking up, there stood john feddes--for i somehow instinctively divined that it was none other than he--in the form of a large, tall, very old man, attired in a light-blue greatcoat he seemed to be steadfastly regarding me with apparent complacency; but i was sadly frightened; and for years after, when passing through the dingy, ill-lighted room out of which i inferred he had come, i used to feel not at all sure that i might not tilt against old john in the dark. i retain vivid recollections of the joy which used to light up the household on my father's arrival; and i remember that i learned to distinguish for myself his sloop when in the offing, by the two slim stripes of white which ran along her sides, and her two square topsails. i have my golden memories, too, of splendid toys that he used to bring home with him,--among the rest, of a magnificent four-wheeled waggon of painted tin, drawn by four wooden horses and a string; and of getting it into a quiet corner, immediately on its being delivered over to me, and there breaking up every wheel and horse, and the vehicle itself, into their original bits, until not two of the pieces were left sticking together. further, i still remember my disappointment at not finding something curious within at least the horses and the wheels; and as unquestionably the main enjoyment derivable from such things is to be had in the breaking of them, i sometimes wonder that our ingenious toymen do not fall upon the way of at once extending their trade, and adding to its philosophy, by putting some of their most brilliant things where nature puts the nut-kernel,--inside. i shall advert to but one other recollection of this period. i have a dreamlike memory of a busy time, when men with gold lace on their breasts, and at least one gentleman with golden epaulets on his shoulders, used to call at my father's house, and fill my newly acquired pockets with coppers; and how they wanted, it was said, to bring my father along with them, to help them to sail their great vessel; but he preferred remaining, it was added, with his own little one. a ship of war, under the guidance of an unskilful pilot, had run aground on a shallow flat on the opposite side of the firth, known as the _inches_; and as the flood of a stream tide was at its height at the time, and straightway began to fall off, it was found, after lightening her of her guns and the greater part of her stores, that she still stuck fast. my father, whose sloop had been pressed into the service, and was loaded to the gunwale with the ordnance, had betrayed an unexpected knowledge of the points of a large war-vessel; and the commander, entering into conversation with him, was so impressed by his skill, that he placed his ship under his charge, and had his confidence repaid by seeing her hauled off into deep water in a single tide. knowing the nature of the bottom,--a soft arenaceous mud, which if beat for some time by the foot or hand, resolved itself into a sort of quicksand, half-sludge, half-water, which, when covered by a competent depth of sea, could offer no effectual resistance to a ship's keel,--the master had set half the crew to run in a body from side to side, till, by the motion generated in this way, the portion of the bank immediately beneath was beaten soft; and then the other moiety of the men, tugging hard on kedge and haulser, drew the vessel off a few feet at a time, till at length, after not a few repetitions of the process, she floated free. of course, on a harder bottom the expedient would not have availed; but so struck was the commander by its efficacy and originality, and by the extent of the master's professional resources, that he strongly recommended him to part with his sloop, and enter the navy, where he thought he had influence enough, he said, to get him placed in a proper position. but as the master's previous experience of the service had been of a very disagreeable kind, and as his position, as at once master and owner of the vessel he sailed, was at least an independent one, he declined acting on the advice. such are some of my earlier recollections. but there was a time of sterner memories at hand. the kelp trade had not yet attained to the importance which it afterwards acquired, ere it fell before the first approaches of free trade; and my father, in collecting a supply for the leith glass works, for which he occasionally acted both as agent and shipmaster, used sometimes to spend whole months amid the hebrides, sailing from station to station, and purchasing here a few tons and there a few hundredweights, until he had completed his cargo. in his last kelp voyage he had been detained in this way from the close of august till the end of october; and at length, deeply laden, he had threaded his way round cape wrath, and through the pentland and across the moray firths, when a severe gale compelled him to seek shelter in the harbour of peterhead. from that port, on the th of november , he wrote my mother the last letter she ever received from him; for on the day after he sailed from it there arose a terrible tempest, in which many seamen perished, and he and his crew were never more heard of. his sloop was last seen by a brother townsman and shipmaster, who, ere the storm came on, had been fortunate enough to secure an asylum for his barque in an english harbour on an exposed portion of the coast. vessel after vessel had been coming ashore during the day; and the beach was strewed with wrecks and dead bodies; but he had marked his townsman's sloop in the offing from mid-day till near evening, exhausting every nautical shift and expedient to keep aloof from the shore; and at length, as the night was falling, the skill and perseverance exerted seemed successful; for, clearing a formidable headland that had lain on the lee for hours, and was mottled with broken ships and drowned men, the sloop was seen stretching out in a long tack into the open sea. "miller's seamanship has saved him once more!" said matheson, the cromarty skipper, as, quitting his place of outlook, he returned to his cabin; but the night fell tempestuous and wild, and no vestige of the hapless sloop was ever after seen. it was supposed that, heavy laden, and labouring in a mountainous sea, she must have started a plank and foundered. and thus perished,--to borrow from the simple eulogium of his seafaring friends, whom i heard long after condoling with my mother,--"one of the best sailors that ever sailed the moray firth." the fatal tempest, as it had prevailed chiefly on the eastern coasts of england and the south of scotland, was represented in the north by but a few bleak, sullen days, in which, with little wind, a heavy ground-swell came rolling in coastwards from the cast, and sent up its surf high against the precipices of the northern sutor. there were no forebodings in the master's dwelling; for his peterhead letter--a brief but hopeful missive--had been just received; and my mother was sitting, on the evening after, beside the household fire, plying the cheerful needle, when the house door, which had been left unfastened, fell open, and i was despatched from her side to shut it. what follows must be regarded as simply the recollection, though a very vivid one, of a boy who had completed his fifth year only a mouth before. day had not wholly disappeared, but it was fast posting on to night, and a grey haze spread a neutral tint of dimness over every more distant object, but left the nearer ones comparatively distinct, when i saw at the open door, within less than a yard of my breast, as plainly as ever i saw anything, a dissevered hand and arm stretched towards me. hand and arm were apparently those of a female: they bore a livid and sodden appearance; and directly fronting me, where the body ought to have been, there was only blank, transparent space, through which i could see the dim forms of the objects beyond. i was fearfully startled, and ran shrieking to my mother, telling what i had seen; and the house-girl whom she next sent to shut the door, apparently affected by my terror, also returned frightened, and said that she too had seen the woman's hand; which, however, did not seem to be the case. and finally, my mother going to the door, saw nothing, though she appeared much impressed by the extremeness of my terror and the minuteness of my description. i communicate the story, as it lies fixed in my memory, without attempting to explain it. the supposed apparition may have been merely a momentary affection of the eye, of the nature described by sir walter scott in his "demonology," and sir david brewster in his "natural magic." but if so, the affection was one of which i experienced no after-return; and its coincidence, in the case, with the probable time of my father's death, seems at least curious. there followed a dreary season, on which i still look back in memory, as on a prospect which, sunshiny and sparkling for a time, has become suddenly enveloped in cloud and storm. i remember my mother's long fits of weeping, and the general gloom of the widowed household; and how, after she had sent my two little sisters to bed,--for such had been the increase of the family,--and her hands were set free for the evening, she used to sit up late at night engaged as a seamstress, in making pieces of dress for such of the neighbours as chose to employ her. my father's new house lay untenanted at the time; and though his sloop had been partially insured, the broker with whom he dealt was, it would seem, on the verge of insolvency, and having raised objections to paying the money, it was long ere any part of it could be realized. and so, with all my mother's industry, the household would have fared out ill, had it not been for the assistance lent her by her two brothers, industrious, hard-working men, who lived with their aged parents, and an unmarried sister, about a bow-shot away, and now not only advanced her money as she needed it, but also took her second child, the elder of my two sisters, a docile little girl of three years, to live with them. i remember i used to go wandering disconsolately about the harbour at this season, to examine the vessels which had come in during the night; and that i oftener than once set my mother a-crying, by asking her why the shipmasters who, when my father was alive, used to stroke my head and slip halfpence into my pockets, never now took any notice of me, or gave me anything? she well knew that the shipmasters--not an ungenerous class of men--had simply failed to recognise their old comrade's child; but the question was only too suggestive, notwithstanding, of both her own loss and mine. i used, too, to climb, day after day, a grassy protuberance of the old coast-line immediately behind my mother's house, that commands a wide reach of the moray firth, and to look wistfully out, long after every one else had ceased to hope, for the sloop with the two stripes of white and the two square topsails. but months and years passed by, and the white stripes and the square topsails i never saw. the antecedents of my father's life impressed me more powerfully during my boyhood than at least aught i acquired at school; and i have submitted them to the reader at considerable length, as not only curious in themselves, but as forming a first chapter in the story of my education. and the following stanzas, written at a time when, in opening manhood, i was sowing my wild oats in verse, may serve to show that they continued to stand out in bold relief on my memory, even after i had grown up:-- "round albyn's western shores, a lonely skiff is coasting slow:--the adverse winds detain: and now she rounds secure the dreaded cliff,[ ] whose horrid ridge beats back the northern main; and now the whirling pentland roars in rain her stern beneath, for favouring breezes rise; the green isles fade, whitens the watery plain. o'er the vexed waves with meteor speed she flies. till moray's distant hills o'er the blue waves arise. who guides that vessel's wanderings o'er the wave; a patient, hardy man, of thoughtful brow; serene and warm of heart, and wisely brave, and sagely skill'd, when gurly breezes blow, to press through angry waves the adventurous prow. age hath not quell'd his strength, nor quench'd desire of generous deed, nor chill'd his bosom's glow; yet to a better world his hopes aspire. ah! this must sure be thee! all hail, my honoured sire! alas! thy latest voyage draws near a close, for death broods voiceless in the darkening sky; subsides the breeze; the untroubled waves repose; the scene is peaceful all. can death be nigh, when thus, mute and unarm'd, his vassals lie? mark ye that cloud! there toils the imprisoned gale; e'en now it comes, with voice uplifted high; resound the shores, harsh screams the rending sail, and roars th' amazed wave, and bursts the thunder peal! three days the tempest raged; on scotia's shore wreck piled on wreck, and corse o'er corse was thrown; her rugged cliffs were red with clotted gore; her dark caves echoed back th' expiring moan; and luckless maidens mourned their lovers gone, and friendless orphans cried in vain for bread; and widow'd mothers wandered forth alone;-- restore, o wave, they cried,--restore our dead! and then the breast they bared, and beat th' unsheltered head. of thee, my sire, what mortal tongue can tell! no friendly bay thy shattered barque received; ev'n when thy dust reposed in ocean cell, strange baseless tales of hope thy friends deceived which oft they doubted sad, or gay believed. at length, when deeper, darker, wax'd the gloom, hopeless they grieved; but 'twas in vain they grieved: if god be truth, 'tis sure no voice of doom, that bids the accepted soul its robes of joy assume." i had been sent, previous to my father's death, to a dame's school, where i was taught to pronounce my letters to such effect in the old scottish mode, that still, when i attempt spelling a word aloud, which is not often,--for i find the process a perilous one,--the _aa's_ and _ee's_, and _uh's_ and _vaus_, return upon me and i have to translate them with no little hesitation as i go along, into the more modish sounds. a knowledge of the letters themselves i had already acquired by studying the signposts of the place,--rare works of art, that excited my utmost admiration, with jugs, and glasses, and bottles, and ships, and loaves of bread upon them; all of which could, as the artists had intended, be actually recognised. during my sixth year i spelt my way, under the dame, through the shorter catechism, the proverbs, and the new testament, and then entered upon her highest form, as a member of the bible class; but all the while the process of acquiring learning had been a dark one, which i slowly mastered, in humble confidence in the awful wisdom of the schoolmistress, not knowing whither it tended, when at once my mind awoke to the meaning of that most delightful of all narratives,--the story of joseph. was there ever such a discovery made before! i actually found out for myself, that the art of reading is the art of finding stories in books, and from that moment reading became one of the most delightful of my amusements. i began by getting into a corner at the dismissal of the school, and there conning over to myself the new-found story of joseph; nor did one perusal serve; the other scripture stories followed,--in especial, the story of samson and the philistines, of david and goliath, of the prophets elijah and elisha; and after these came the new testament stories and parables. assisted by my uncles, i began to collect a library in a box of birch-bark about nine inches square, which i found quite large enough to contain a great many immortal works,--jack the giant-killer, and jack and the bean-stalk, and the yellow dwarf, and blue beard, and sinbad the sailor, and beauty and the beast, and aladdin and the wonderful lamp, with several others of resembling character. those intolerable nuisances the useful-knowledge books had not yet arisen, like tenebrious stars, on the educational horizon, to darken the world, and shed their blighting influence on the opening intellect of the "youth-hood;" and so, from my rudimental books--books that made themselves truly such by their thorough assimilation with the rudimental mind--i passed on, without being conscious of break or line of division, to books on which the learned are content to write commentaries and dissertations, but which i found to be quite as nice children's books as any of the others. old homer wrote admirably for little folk, especially in the odyssey; a copy of which,--in the only true translation extant,--for, judging from its surpassing interest, and the wrath of critics, such i hold that of pope to be,--i found in the house of a neighbour. next came the iliad; not, however, in a complete copy, but represented by four of the six volumes of bernard lintot. with what power, and at how early an age, true genius impresses! i saw, even at this immature period, that no other writer could cast a javelin with half the force of homer. the missiles went whizzing athwart his pages; and i could see the momentary gleam of the steel, ere it buried itself deep in brass and bull-hide. i next succeeded in discovering for myself a child's book, of not less interest than even the iliad, which might, i was told, be read on sabbaths, in a magnificent old edition of the "pilgrim's progress," printed on coarse whity-brown paper, and charged with numerous woodcuts, each of which occupied an entire page, that, on principles of economy, bore letter-press on the other side. and such delightful prints as these were! it must have been some such volume that sat for its portrait to wordsworth, and which he so exquisitely describes as "profuse in garniture of wooden cuts, strange and uncouth; dire faces, figures dire, sharp-knee'd, sharp elbow'd, and lean-ankled too, with long and ghastly shanks,--forms which, once seen, could never be forgotten." in process of time i had devoured, besides these genial works robinson crusoe, gulliver's travels, ambrose on angels, the "judgment chapter" in howie's scotch worthies, byron's narrative, and the adventures of philip quarll, with a good many other adventures and voyages, real and fictitious, part of a very miscellaneous collection of books made by my father. it was a melancholy little library to which i had fallen heir. most of the missing volumes had been with the master aboard his vessel when he perished. of an early edition of cook's voyages, all the volumes were now absent save the first; and a very tantalizing romance, in four volumes,--mrs. ratcliff's "mysteries of udolpho," was represented by only the earlier two. small as the collection was, it contained some rare books,--among the rest, a curious little volume, entitled "the miracles of nature and art," to which we find dr. johnson referring, in one of the dialogues chronicled by boswell, as scarce even in his day, and which had been published, he said, some time in the seventeenth century by a bookseller whose shop hung perched on old london bridge, between sky and water. it contained, too, the only copy i ever saw of the "memoirs of a protestant condemned to the galleys of france for his religion,"--a work interesting from the circumstance that--though it bore another name on its title-page--it had been translated from the french for a few guineas by poor goldsmith, in his days of obscure literary drudgery, and exhibited the peculiar excellencies of his style. the collection boasted, besides, of a curious old book, illustrated by very uncouth plates, that detailed the perils and sufferings of an english sailor who had spent his best years of life as a slave in morocco. it had its volumes of sound theology, too, and of stiff controversy,--flavel's works, and henry's commentary, and hutchinson on the lesser prophets, and a very old treatise on the revelation, with the title-page away, and blind jameson's volume on the hierarchy, with first editions of naphthali, the cloud of witnesses, and the hind let loose. but with these solid authors i did not venture to grapple until long after this time. of the works of fact and incident which it contained, those of the voyagers were my especial favourites. i perused with avidity the voyages of anson, drake, raleigh, dampier, and captain woods rogers; and my mind became so filled with conceptions of what was to be seen and done in foreign parts, that i wished myself big enough to be a sailor, that i might go and see coral islands and burning mountains, and hunt wild beasts and fight battles. i have already made mention of my two maternal uncles; and referred, at least incidentally, to their mother, as the friend and relative of my fathers aged cousin, and, like her, a great-grand-child of the last curate of nigg. the curate's youngest daughter had been courted and married by a somewhat wild young farmer, of the clan ross, but who was known, like the celebrated highland outlaw, from the colour of his hair, as roy, or the red. donald roy was the best club-player in the district; and as king james's "book of sports" was not deemed a very bad one in the semi-celtic parish of nigg, the games in which donald took part were usually played on the sabbath. about the time of the revolution, however, he was laid hold of by strong religious convictions, heralded, say the traditions of the district, by events that approximated in character to the supernatural; and donald became the subject of a mighty change. there is a phase of the religious character, which in the south of scotland belongs to the first two ages of presbytery, but which disappeared ere its third establishment under william of nassau, that we find strikingly exemplified in the welches, pedens, and cargills of the times of the persecution, and in which a sort of wild machinery of the supernatural was added to the commoner aspects of a living christianity. the men in whom it was exhibited were seers of visions and dreamers of dreams; and, standing on the very verge of the natural world, they looked far into the world of spirits, and had at times their strange glimpses of the distant and the future. to the north of the grampians, as if born out of due season, these seers pertain to a later age. they flourished chiefly in the early part of the last century; for it is a not uninstructive fact, that in the religious history of scotland, the eighteenth century of the highland and semi-highland districts of the north corresponded in many of its traits to the seventeenth century of the saxon-peopled districts of the south; and donald roy was one of the most notable of the class. the anecdotes regarding him which still float among the old recollections of ross-shire, if transferred to peden or welch, would be found entirely in character with the strange stories that inlay the biographies of these devoted men, and live so enduringly in the memory of the scottish people. living, too, in an age in which, like the covenanters of a former century, the highlander still retained his weapons, and knew how to use them, donald had, like the patons, hackstons, and balfours of the south, his dash of the warlike spirit; and after assisting his minister, previous to the rebellion of , in what was known as the great religious revival of nigg, he had to assist him, shortly after, in pursuing a band of armed caterans, that, descending from the hills, swept the parish of its cattle. and coming up with the outlaws in the gorge of a wild highland glen, no man of his party was more active in the fray that followed than old donald, or exerted himself to better effect in re-capturing the cattle. i need scarce add, that he was an attached member of the church of scotland: but he was not destined to die in her communion. donald's minister, john balfour of nigg--a man whose memory is still honoured in the north--died in middle life, and an unpopular presentee was obtruded on the people. the policy of robertson prevailed at the time; gillespie had been deposed only four years previous, for refusing to assist in the disputed settlement of inverkeithing; and four of the nigg presbytery, overawed by the stringency of the precedent, repaired to the parish church to conduct the settlement of the obnoxious licentiate, and introduce him to the parishioners. they found, however, only an empty building; and, notwithstanding the ominous absence of the people, they were proceeding in shame and sorrow with their work, when a venerable man, far advanced in life, suddenly appeared before them, and, solemnly protesting against the utter mockery of such a proceeding, impressively declared, "that if they settled a man to the _walls_ of that kirk, the blood of the parish of nigg would be required at their hands." both dr. hetherington and dr. merle d'aubigné record the event; but neither of these accomplished historians seems to have been aware of the peculiar emphasis which a scene that would have been striking in any circumstances derived from the character of the protester--old donald roy. the presbytery, appalled, stopt short in the middle of its work; nor was it resumed till an after day, when, at the command of the moderate majority of the church--a command not unaccompanied by significant reference to-the fate of gillespie--the forced settlement was consummated. donald, who carried the entire parish with him, continued to cling to the national church for nearly ten years after, much befriended by one of the most eminent and influential divines of the north--fraser of alness--the author of a volume on sanctification, still regarded as a standard work by scottish theologians. but as neither the people nor their leader ever entered on any occasion the parish church, or heard the obnoxious presentee, the presbytery at length refused to tolerate the irregularity by extending to them as before the ordinary church privileges; and so they were lost to the establishment, and became seceders. and in the communion of that portion of the secession known as the burghers, donald died several years after, at a patriarchal old age. among his other descendants, he had three grand-daughters, who were left orphans at an early age by the death of both their parents, and whom the old man, on their bereavement, had brought to his dwelling to live with him. they had small portions apiece, derived from his son-in-law, their father, which did not grow smaller under the care of donald; and as each of the three was married in succession out of his family, he added to all his other kindnesses the gift of a gold ring. they had been brought up under his eye sound in the faith; and donald's ring had, in each case, a mystic meaning;--they were to regard it, he told them, as the wedding ring of their _other husband_, the head of the church, and to be faithful spouses to him in their several households. nor did the injunction, nor the significant symbol with which it was accompanied, prove idle in the end. they all brought the savour of sincere piety into their families. the grand-daughter with whom the writer was more directly connected, had been courted and married by an honest and industrious but somewhat gay young tradesman, but she proved, under god, the means of his conversion; and their children, of whom eight grew up to be men and women, were reared in decent frugality, and the exercise of honest principles carefully instilled. her husband's family had, like that of my paternal ancestors, been a seafaring one. his father, after serving for many years on shipboard, passed the latter part of his life as one of the armed boatmen that, during the last century, guarded the coasts in behalf of the revenue; and his only brother, the boatman's son, an adventurous young sailor had engaged in admiral vernon's unfortunate expedition, and left his bones under the walls of carthagena; but he himself pursued the peaceful occupation of a shoemaker, and, in carrying on his trade, usually employed a few journeymen, and kept a few apprentices. in course of time the elder daughters of the family married, and got households of their own; but the two sons, my uncles, remained under the roof of their parents, and at the time when my father perished, they were both in middle life. and, deeming themselves called on to take his place in the work of instruction and discipline, i owed to them much more of my real education than to any of the teachers whose schools i afterwards attended. they both bore a marked individuality of character, and were much the reverse of commonplace or vulgar men. my elder uncle, james, added to a clear head and much native sagacity, a singularly retentive memory, and great thirst of information. he was a harness-maker, and wrought for the farmers of an extensive district of country; and as he never engaged either journeyman or apprentice, but executed all his work with his own hands, his hours of labour, save that he indulged in a brief pause as the twilight came on, and took a mile's walk or so, were usually protracted from six o'clock in the morning till ten at night. such incessant occupation left him little time for reading; but he often found some one to read beside him during the day; and in the winter evenings his portable bench used to be brought from his shop at the other end of the dwelling, into the family sitting-room, and placed beside the circle round the hearth, where his brother alexander, my younger uncle, whose occupation left his evenings free, would read aloud from some interesting volume for the general benefit,--placing himself always at the opposite side of the bench, so as to share in the light of the worker. occasionally the family circle would be widened by the accession of from two to three intelligent neighbours, who would drop in to listen; and then the book, after a space, would be laid aside, in order that its contents might be discussed in conversation. in the summer months uncle james always spent some time in the country, in looking after and keeping in repair the harness of the farmers for whom he wrought; and during his journeys and twilight walks on these occasions there was not an old castle, or hill-fort, or ancient encampment, or antique ecclesiastical edifice, within twenty miles of the town, which he had not visited and examined over and over again. he was a keen local antiquary; knew a good deal about the architectural styles of the various ages, at a time when these subjects were little studied or known; and possessed more traditionary lore, picked up chiefly in his country journeys, than any man i ever knew. what he once heard he never forgot; and the knowledge which he had acquired he could communicate pleasingly and succinctly, in a style which, had he been a writer of books, instead of merely a reader of them, would have had the merit of being clear and terse, and more laden with meaning than words. from his reputation for sagacity, his advice used to be much sought after by the neighbours in every little difficulty that came their way; and the counsel given was always shrewd and honest. i never knew a man more entirely just in his dealings than uncle james, or who regarded every species of meanness with a more thorough contempt. i soon learned to bring my story-books to his workshop, and became, in a small way, one of his _readers_,--greatly more, however, as may be supposed, on my own account than his. my books were not yet of the kind which he would have chosen for himself; but he took an interest in _my_ interest; and his explanations of all the hard words saved me the trouble of turning over a dictionary. and when tired of reading, i never failed to find rare delight in his anecdotes and old-world stories, many of which were not to be found in books, and all of which, without apparent effort on his own part, he could render singularly amusing. of these narratives, the larger part died with him; but a portion of them i succeeded in preserving in a little traditionary work published a few years after his death. i was much a favourite with uncle james,--even more, i am disposed to think, on my father's account than on that of his sister, my mother. my father and he had been close friends for years; and in the vigorous and energetic sailor he had found his _beau-idéal_ of a man. my uncle alexander was of a different cast from his brother both in intellect and temperament; but he was characterized by the same strict integrity; and his religious feelings, though quiet and unobtrusive, were perhaps more deep. james was somewhat of a humorist, and fond of a good joke. alexander was grave and serious; and never, save on one solitary occasion, did i know him even attempt a jest. on hearing an intelligent but somewhat eccentric neighbour observe, that "all flesh is grass," in a strictly physical sense, seeing that all the flesh of the herbivorous animals is elaborated from vegetation, and all the flesh of the carnivorous animals from that of the herbivorous ones, uncle sandy remarked that, knowing, as he did, the piscivorous habits of the cromarty folk, he should surely make an exception in his generalization, by admitting that in at least one village "all flesh is fish." my uncle had acquired the trade of the cartwright, and was employed in a workshop at glasgow at the time the first war of the french revolution broke out; when, moved by some such spirit as possessed his uncle,--the victim of admiral vernon's unlucky expedition,--or old donald roy, when he buckled himself to his highland broadsword, and set out in pursuit of the caterans,--he entered the navy. and during the eventful period which intervened between the commencement of the war and the peace of , there was little either suffered or achieved by his countrymen in which he had not a share. he sailed with nelson; witnessed the mutiny at the nore; fought under admiral duncan at camperdown, and under sir john borlase warren at loch swilly; assisted in capturing the généroux and guillaume tell, two french ships of the line; was one of the seamen who, in the egyptian expedition, were drafted out of lord keith's fleet to supply the lack of artillerymen in the army of sir ralph abercromby; had a share in the danger and glory of the landing in egypt; and fought in the battle of th march, and in that which deprived our country of one of her most popular generals. he served, too, at the siege of alexandria. and then, as he succeeded in procuring his discharge during the short peace of , he returned home with a small sum of hardly-earned prize-money, heartily sick of war and bloodshed. i was asked not long ago by one of his few surviving comrades, whether my uncle had ever told me that _their_ gun was the first landed in egypt, and the first dragged up the sand-bank immediately over the beach, and how hot it grew under their hands, as, with a rapidity unsurpassed along the line, they poured out in thick succession its iron discharges upon the enemy. i had to reply in the negative. all my uncle's narratives were narratives of what he had seen--not of what he had done; and when, perusing, late in life, one of his favourite works--dr. keith's "signs of the times"--he came to the chapter in which that excellent writer describes the time of hot naval warfare which immediately followed the breaking out of war, as the period in which the second vial was poured out on the sea, and in which the waters "became as the blood of a dead man, so that every living soul died in the sea," i saw him bend his head in reverence as he remarked, "prophecy, i find, gives to all our glories but a single verse, and it is a verse of judgment." uncle sandy, however, did not urge the peace principles which he had acquired amid scenes of death and carnage, into any extravagant consequences; and on the breaking out, in , of the second war of the revolution, when napoleon threatened invasion from brest and boulogne, he at once shouldered his musket as a volunteer. he had not his brother's fluency of speech; but his narratives of what he had seen were singularly truthful and graphic; and his descriptions of foreign plants and animals, and of the aspect of the distant regions which he had visited, had all the careful minuteness of those of a dampier. he had a decided turn for natural history. my collection contains a murex, not unfrequent in the mediterranean, which he found time enough to transfer, during the heat of the landing in egypt, from the beach to his pocket; and the first ammonite i ever saw was a specimen, which i still retain, that he brought home with him from one of the liassic deposits of england. early on the sabbath evenings i used regularly to attend at my uncle's with two of my maternal cousins, boys of about my own age, and latterly with my two sisters, to be catechized, first on the shorter catechism, and then on the mother's catechism of willison. on willison my uncles always cross-examined us, to make sure that we understood the short and simple questions; but, apparently regarding the questions of the shorter catechism as seed sown for a future day, they were content with having them well fixed in our memories. there was a sabbath class taught in the parish church at the time by one of the elders; but sabbath-schools my uncles regarded as merely compensatory institutions, highly creditable to the teachers, but very discreditable indeed to the parents and relatives of the taught; and so they of course never thought of sending us there. later in the evening, after a short twilight walk, for which the sedentary occupation of my uncle james formed an apology, but in which my uncle alexander always shared, and which usually led them into solitary woods, or along an unfrequented sea-shore, some of the old divines were read; and i used to take my place in the circle, though, i am afraid, not to much advantage. i occasionally caught a fact, or had my attention arrested for a moment by a simile or metaphor; but the trains of close argument, and the passages of dreary "application," were always lost. footnote: [ ] cape wrath. chapter iii. "at wallace' name what scottish blood but boils up in a spring-tide flood! oft have our fearless fathers strode by wallace' side, still pressing onward, red wat shod, or glorious died."--burns. i first became thoroughly a scot some time in my tenth year; and the consciousness of country has remained tolerably strong within me ever since. my uncle james had procured for me from a neighbour the loan of a common stall-edition of blind harry's "wallace," as modernized by hamilton; but after reading the first chapter,--a piece of dull genealogy, broken into very rude rhyme,--i tossed the volume aside as uninteresting; and only resumed it at the request of my uncle, who urged that, simply for _his_ amusement and gratification, i should read some three or four chapters more. accordingly, the three or four chapters more i did read;--i read "how wallace killed young selbie the constable's son;" "how wallace fished in irvine water;" and "how wallace killed the churl with his own staff in ayr;" and then uncle james told me, in the quiet way in which he used to make a joke tell, that the book seemed to be rather a rough sort of production, filled with accounts of quarrels and bloodshed, and that i might read no more of it unless i felt inclined. but i now did feel inclined very strongly, and read on with increasing astonishment and delight. i was intoxicated with the fiery narratives of the blind minstrel,--with his fierce breathings of hot, intolerant patriotism, and his stories of astonishing prowess; and, glorying in being a scot, and the countryman of wallace and the graham, i longed for a war with the southron, that the wrongs and sufferings of these noble heroes might yet be avenged. all i had previously heard and read of the marvels of foreign parts, of the glories of modern battles, seemed tame and commonplace, compared with the incidents in the life of wallace; and i never after vexed my mother by wishing myself big enough to be a sailor. my uncle sandy, who had some taste for the refinements of poetry, would fain have led me on from the exploits of wallace to the "life of the bruce," which, in the form of a not very vigorous imitation of dryden's "virgil," by one harvey, was bound up in the same volume, and which my uncle deemed the better-written life of the two. and so far as the mere amenities of style were concerned, he was, i daresay, right. but i could not agree with him. harvey was by much too fine and too learned for me; and it was not until some years after, when i was fortunate enough to pick up one of the later editions of barbour's "bruce," that the hero-king of scotland assumed his right place in my mind beside its hero-guardian. there are stages of development in the immature youth of individuals, that seem to correspond with stages of development in the immature youth of nations; and the recollections of this early time enable me, in some measure, to understand how it was that, for hundreds of years, blind harry's "wallace," with its rude and naked narrative, and its exaggerated incident, should have been, according to lord hailes, the bible of the scotch people. i quitted the dame's school at the end of the first twelvemonth, after mastering that grand acquirement of my life,--the art of holding converse with books; and was transferred straightforth to the grammar school of the parish, at which there attended at this time about a hundred and twenty boys, with a class of about thirty individuals more, much looked down upon by the others, and not deemed greatly worth the counting, seeing that it consisted of only _lassies_. and here, too, the early individual development seems nicely correspondent with an early national one. in his depreciatory estimate of contemporary woman, the boy is always a true savage. the old parish school of the place had been nobly situated in a snug corner, between the parish churchyard and a thick wood; and from the interesting centre which it formed, the boys, when tired of making dragoon-horses of the erect head-stones, or of leaping along the flat-laid memorials, from end to end of the grave-yard, "without touching grass," could repair to the taller trees, and rise in the world by climbing among them. as, however, they used to encroach, on these latter occasions, upon the laird's pleasure-grounds, the school had been removed ere my time to the sea-shore; where, though there were neither tombstones nor trees, there were some balancing advantages, of a kind which perhaps only boys of the old school could have adequately appreciated. as the school-windows fronted the opening of the firth, not a vessel could enter the harbour that we did not see; and, improving through our opportunities, there was perhaps no educational institution in the kingdom in which all sorts of barques and carvels, from the fishing yawl to the frigate, could be more correctly drawn on the slate, or where any defect in hulk or rigging, in some faulty delineation, was surer of being more justly and unsparingly criticised. further, the town, which drove a great trade in salted pork at the time, had a killing-place not thirty yards from the school-door, where from eighty to a hundred pigs used sometimes to die for the general good in a single day; and it was a great matter to hear, at occasional intervals, the roar of death outside rising high over the general murmur within, or to be told by some comrade, returned from his five minutes' leave of absence, that a hero of a pig had taken three blows of the hatchet ere it fell, and that even after its subjection to the sticking process, it had got hold of jock keddie's hand in its mouth, and almost smashed his thumb. we learned, too, to know, from our signal opportunities of observation, not only a good deal about pig-anatomy,--especially about the detached edible parts of the animal, such as the spleen and the pancreas, and at least one other very palatable viscus besides,--but became knowing also about the _take_ and curing of herrings. all the herring boats during the fishing season passed our windows on their homeward way to the harbour; and, from their depth in the water, we became skilful enough to predicate the number of crans aboard of each with wonderful judgment and correctness. in days of good general fishings, too, when the curing-yards proved too small to accommodate the quantities brought ashore, the fish used to be laid in glittering heaps opposite the school-house door; and an exciting scene, that combined the bustle of the workshop with the confusion of the crowded fair, would straightway spring up within twenty yards of the forms at which we sat, greatly to our enjoyment, and, of course, not a little to our instruction. we could see, simply by peering over book or slate, the curers going about rousing their fish with salt, to counteract the effects of the dog-day sun; bevies of young women employed as gutters, and horridly incarnadined with blood and viscera, squatting around the heaps, knife in hand, and plying with busy fingers their well-paid labours, at the rate of sixpence per hour; relays of heavily-laden fish-wives bringing ever and anon fresh heaps of herrings in their creels; and outside of all, the coopers hammering as if for life and death,--now tightening hoops, and now slackening them, and anon caulking with bulrush the leaky seams. it is not every grammar school in which such lessons are taught as those in which all were initiated, and in which all became in some degree accomplished, in the grammar school of cromarty! the building in which we met was a low, long, straw-thatched cottage, open from gable to gable, with a mud floor below, and an unlathed roof above; and stretching along the naked rafters, which, when the master chanced to be absent for a few minutes, gave noble exercise in climbing, there used frequently to lie a helm, or oar, or boathook, or even a foresail,--the spoil of some hapless peat-boat from the opposite side of the firth. the highland boatmen of ross had carried on a trade in peats for ages with the saxons of the town; and as every boat owed a long-derived perquisite of twenty peats to the grammar school, and as payment was at times foolishly refused, the party of boys commissioned by the master to exact it almost always succeeded, either by force or stratagem, in securing and bringing along with them, in behalf of the institution, some spar, or sail, or piece of rigging, which, until redeemed by special treaty, and the payment of the peats, was stowed up over the rafters. these peat-expeditions, which were intensely popular in the school, gave noble exercise to the faculties. it was always a great matter to see, just as the school met, some observant boy appear, cap in hand, before the master, and intimate the fact of an arrival at the shore, by the simple words, "peat-boat, sir." the master would then proceed to name a party, more or less numerous, according to the exigency; but it seemed to be matter of pretty correct calculation that, in the cases in which the peat claim was disputed, it required about twenty boys to bring home the twenty peats, or, lacking these, the compensatory sail or spar. there were certain ill-conditioned boatmen who almost always resisted, and who delighted to tell us--invariably, too, in very bad english--that our perquisite was properly the hangman's perquisite,[ ] made over to us because we were _like him_; not seeing--blockheads as they were!--that the very admission established in full the rectitude of our claim, and gave to us, amid our dire perils and faithful contendings, the strengthening consciousness of a just quarrel. in dealing with these recusants, we used ordinarily to divide our forces into two bodies, the larger portion of the party filling their pockets with stones, and ranging themselves on some point of vantage, such as the pier-head; and the smaller stealing down as near the boat as possible, and mixing themselves up with the purchasers of the peats. we then, after due warning, opened fire upon the boatmen; and, when the pebbles were hopping about them like hailstones, the boys below commonly succeeded in securing, under cover of the fire, the desired boathook or oar. and such were the ordinary circumstances and details of this piece of spartan education; of which a townsman has told me he was strongly reminded when boarding, on one occasion, under cover of a well-sustained discharge of musketry, the vessel of an enemy that had been stranded on the shores of berbice. the parish schoolmaster was a scholar and an honest man, and if a boy really wished to learn, _he_ certainly could teach him. he had attended the classes at aberdeen during the same sessions as the late dr. mearns, and in mathematics and the languages had disputed the prize with the doctor; but he had failed to get on equally well in the world; and now, in middle life, though a licentiate of the church, he had settled down to be what he subsequently remained--the teacher of a parish school. there were usually a few grown-up lads under his tuition--careful sailors, that had stayed ashore during the winter quarter to study navigation as a science,--or tall fellows, happy in the patronage of the great, who, in the hope of being made excisemen, had come to school to be initiated in the mysteries of gauging,--or grown young men, who, on second thoughts, and somewhat late in the day, had recognised the church as their proper vocation; and these used to speak of the master's acquirements and teaching ability in the very highest terms. he himself, too, could appeal to the fact, that no teacher in the north had ever sent more students to college, and that his better scholars almost always got on well in life. but then, on the other hand, the pupils who wished to do nothing--a description of individuals that comprised fully two-thirds of all the younger ones--were not required to do much more than they wished; and parents and guardians were loud in their complaints that he was no suitable schoolmaster for them; though the boys themselves usually thought him quite suitable enough. he was in the habit of advising the parents or relations of those he deemed his clever lads, to give them a classical education; and meeting one day with uncle james, he urged that i should be put on latin. i was a great reader, he said; and he found that when i missed a word in my english tasks, i almost always substituted a synonym in the place of it. and so, as uncle james had arrived, on data of his own, at a similar conclusion, i was transferred from the english to the latin form, and, with four other boys, fairly entered on the "rudiments." i laboured with tolerable diligence for a day or two; but there was no one to tell me what the rules meant, or whether they really meant anything; and when i got on as far as _penna_, a pen, and saw how the changes were rung on one poor word, that did not seem to be of more importance in the old language than in the modern one, i began miserably to flag, and to long for my english reading, with its nice amusing stories, and its picture-like descriptions. the rudiments was by far the dullest book i had ever seen. it embodied no thought that i could perceive,--it certainly contained no narrative,--it was a perfect contrast to not only the "life and adventures of sir william wallace," but to even the voyages of cook and anson. none of my class-fellows were by any means bright;--they had been all set on latin without advice of the master; and yet, when he learned, which he soon did, to distinguish and call us up to our tasks by the name of the "heavy class," i was, in most instances, to be found at its nether end. shortly after, however, when we got a little farther on, it was seen that i had a decided turn for translation. the master, good simple man that he was, always read to us in english, as the school met, the piece of latin given us as our task for the day; and as my memory was strong enough to carry away the whole translation in its order, i used to give him back in the evening, word for word, his own rendering, which satisfied him on most occasions tolerably well. there were none of us much looked after; and i soon learned to bring books of amusement to the school with me, which, amid the babel confusion of the place, i contrived to read undetected. some of them, save in the language in which they were written, were identical with the books proper to the place. i remember perusing by stealth in this way, dryden's "virgil," and the "ovid" of dryden and his friends; while ovid's own "ovid," and virgil's own "virgil," lay beside me, sealed up in the fine old tongue, which i was thus throwing away my only chance of acquiring. one morning, having the master's english rendering of the day's task well fixed in my memory, and no book of amusement to read, i began gossiping with my nearest class-fellow, a very tall boy, who ultimately shot up into a lad of six feet four, and who on most occasions sat beside me, as lowest in the form save one. i told him about the tall wallace and his exploits; and so effectually succeeded in awakening his curiosity, that i had to communicate to him, from beginning to end, every adventure recorded by the blind minstrel. my story-telling vocation once fairly ascertained, there was, i found, no stopping in my course. i had to tell all the stories i ever heard or read; all my father's adventures, so far as i knew them, and all my uncle sandy's,--with the story of gulliver, and philip quarll, and robinson crusoe,--of sinbad, and ulysses, and mrs. radcliffe's heroine emily, with, of course, the love-passages left out; and at length, after weeks and months of narrative, i found my available stock of acquired fact and fiction fairly exhausted. the demand on the part of my class-fellows was, however, as great and urgent as ever; and, setting myself, in the extremity of the case, to try my ability of original production, i began to dole out to them by the hour and the diet, long extempore biographies, which proved wonderfully popular and successful. my heroes were usually warriors like wallace, and voyagers like gulliver, and dwellers in desolate islands like robinson crusoe; and they had not unfrequently to seek shelter in huge deserted castles, abounding in trap-doors and secret passages, like that of udolpho. and finally, after much destruction of giants and wild beasts, and frightful encounters with magicians and savages, they almost invariably succeeded in disentombing hidden treasures to an enormous amount, or in laying open gold mines, and then passed a luxurious old age, like that of sinbad the sailor, at peace with all mankind, in the midst of confectionery and fruits. the master had a tolerably correct notion of what was going on in the "heavy class;"--the stretched-out necks, and the heads clustered together, always told their own special story when i was engaged in telling mine; but, without hating the child, he spared the rod, and simply did what he sometimes allowed himself to do--bestowed a nickname upon me. i was the _sennachie_, he said; and as the sennachie i might have been known so long as i remained under his charge, had it not been that, priding himself upon his gaelic, he used to bestow upon the word the full celtic pronunciation, which, agreeing but ill with the teutonic mouths of my school-fellows, militated against its use; and so the name failed to take. with all my carelessness, i continued to be a sort of favourite with the master; and, when at the general english lesson, he used to address to me little quiet speeches, vouchsafed to no other pupil, indicative of a certain literary ground common to us, on which the others had not entered. "that, sir," he has said, after the class had just perused, in the school collection, a _tatler_ or _spectator_,--"that, sir, is a good paper;--it's an _addison_;" or, "that's one of steele's, sir;" and on finding in my copy-book, on one occasion, a page filled with rhymes, which i had headed "poem on care," he brought it to his desk, and, after reading it carefully over, called me up, and with his closed penknife, which served as a pointer, in the one hand, and the copy-book brought down to the level of my eyes in the other, began his criticism. "that's bad grammar, sir," he said, resting the knife-handle on one of the lines; "and here's an ill-spelt word; and there's another; and you have not at all attended to the punctuation; but the general sense of the piece is good,--very good indeed, sir." and then he added, with a grim smile, "_care_, sir, is, i daresay, as you remark, a very bad thing; but you may safely bestow a little more of it on your spelling and your grammar." the school, like almost all the other grammar-schools of the period in scotland, had its yearly cock-fight, preceded by two holidays and a half, during which the boys occupied themselves in collecting and bringing up their cocks. and such always was the array of fighting birds mustered on the occasion, that the day of the festival, from morning till night, used to be spent in fighting out the battle. for weeks after it had passed, the school-floor would continue to retain its deeply-stained blotches of blood, and the boys would be full of exciting narratives regarding the glories of gallant birds, who had continued to fight until both their eyes had been picked out, or who, in the moment of victory, had dropped dead in the middle of the cock-pit. the yearly fight was the relic of a barbarous age; and, in at least one of its provisions, there seemed evidence that it was that of an intolerant age also: every pupil at school, without exemption, had his name entered on the subscription-list, as a cock-fighter, and was obliged to pay the master at the rate of twopence per head, ostensibly for leave to bring his birds to the pit; but, amid the growing humanities of a better time, though the twopences continued to be exacted, it was no longer imperative to bring the birds; and availing myself of the liberty i never brought any. nor, save for a few minutes, on two several occasions, did i ever attend the fight. had the combat been one among the boys themselves, i would readily enough have done my part, by meeting with any opponent of my years and standing; but i could not bear to look at the bleeding birds. and so i continued to pay my yearly sixpence, as a holder of three cocks,--the lowest sum deemed in any degree genteel,--but remained simply a fictitious or paper cock-fighter, and contributed in no degree to the success of the _head-stock_ or leader, to whose party, in the general division of the school, it was my lot to fall. neither, i must add, did i learn to take an interest in the sacrificial orgies of the adjoining slaughter-house. a few of the chosen school-boys were permitted by the killers to exercise at times the privilege of knocking down a pig, and even, on rare occasions, to essay the sticking; but i turned with horror from both processes; and if i drew near at all, it was only when some animal, scraped and cleaned, and suspended from the beam, was in the course of being laid open by the butcher's knife, that i might mark the forms of the viscera, and the positions which they occupied. to my dislike of the annual cock-fight my uncles must have contributed. they were loud in their denunciations of the enormity; and on one occasion, when a neighbour was unlucky enough to remark, in extenuation, that the practice had been handed down to us by pious and excellent men, who seemed to see nothing wrong in it, i saw the habitual respect for the old divines give way, for at least a moment. uncle sandy hesitated under apparent excitement; but, quick and fiery as lightning, uncle james came to his rescue. "yes, excellent men!" said my uncle, "but the excellent men of a rude and barbarous age; and, in some parts of their character, tinged by its barbarity. for the cock-fight which these excellent men have bequeathed to us, they ought to have been sent to bridewell for a week, and fed upon bread and water." uncle james was, no doubt, over hasty, and felt so a minute after; but the practice of fixing the foundations of ethics on a _they themselves did it_, much after the manner in which the schoolmen fixed the foundations of their nonsensical philosophy on a "_he himself said it_," is a practice which, though not yet exploded in even very pure churches, is always provoking, and not quite free from peril to the worthies, whether dead or alive, in whose precedents the moral right is made to rest. in the class of minds represented among the people by that of uncle james, for instance, it would be much easier to bring down even the old divines, than to bring up cock-fighting. my native town had possessed, for at least an age or two previous to that of my boyhood, its sprinkling of intelligent, book-consulting mechanics and tradesfolk; and as my acquaintance gradually extended among their representatives and descendants, i was permitted to rummage, in the pursuit of knowledge, delightful old chests and cupboards, filled with tattered and dusty volumes. the moiety of my father's library which remained to me consisted of about sixty several works; my uncle possessed about a hundred and fifty more; and there was a literary cabinet-maker in the neighbourhood, who had once actually composed a poem of thirty lines on the hill of cromarty, whose collection of books, chiefly poetical, amounted to from about eighty to a hundred. i used to be often at nights in the workshop of the cabinet-maker, and was sometimes privileged to hear him repeat his poem. there was not much admiration of poets or poetry in the place; and my praise, though that of a very young critic, had always the double merit of being both ample and sincere. i knew the very rocks and trees which his description embraced,--had heard the birds to which he referred, and seen the flowers; and as the hill had been of old a frequent scene of executions, and had borne the gallows of the sheriffdom on its crest, nothing could be more definite than the grave reference, in his opening line, to "the verdant rising of the _gallow_-hill." and so i thought a very great deal of his poem, and what i thought i said; and he, on the other hand, evidently regarded me as a lad of extraordinary taste and discernment for my years. there was another mechanic in the neighbourhood,--a house-carpenter, who, though not a poet, was deeply read in books of all kinds, from the plays of farquhar to the sermons of flavel; and as both his father and grandfather--the latter, by the way, a porteous-mob man, and the former a personal friend of poor fergusson the poet--had also been readers and collectors of books, he possessed a whole pressful of tattered, hard-working volumes, some of them very curious ones; and to me he liberally extended, what literary men always value, "the full freedom of the press." but of all my occasional benefactors in this way, by far the greatest was poor old francie, the retired clerk and supercargo. francie was naturally a man of fair talent and active curiosity. nor was he by any means deficient in acquirement. he wrote and figured well, and knew a good deal about at least the theory of business; and when articled in early life to a cromarty merchant and shopkeeper, it was with tolerably fair prospects of getting on in the world. he had, however, a certain infirmity of brain, which rendered both talent and acquirement of but little avail, and that began to manifest itself very early. while yet an apprentice, on ascertaining that the way was clear, he used, though grown a tall lad, to bolt out from behind the counter into the middle of a green directly opposite, and there, joining in the sports of some group of youngsters, which the place rarely wanted, he would play out half a game at marbles, or honey-pots, or hy-spy, and, when he saw his master or a customer approaching, bolt back again the thing was not deemed seemly; but francie, when spoken to on the subject, could speak as sensibly as any young person of his years. he needed relaxation, he used to say, though he never suffered it to interfere with his proper business; and where was there safer relaxation to be found than among innocent children? this, of course, was eminently rational, and even virtuous. and so, when his term of apprenticeship had expired, francie was despatched, not without hope of success, to newfoundland,--where he had relations extensively engaged in the fishing trade,--to serve as one of their clerks. he was found to be a competent clerk; but unluckily there was but little known of the interior of the island at the time; and some of the places most distant from st. john's, such as the bay and river of exploits, bore tempting names; and so, after francie had made many inquiries at the older inhabitants regarding what was to be seen amid the scraggy brushwood and broken rocks of the inner country, a morning came in which he was reported missing at the office; and little else could be learned respecting him, than that at early dawn he had been seen setting out for the woods, provided with staff and knapsack. he returned in about a week, worn out and half-starved. he had not been so successful as he had anticipated, he said, in providing himself by the way with food, and so he had to turn back ere he could reach the point on which he had previously determined; but he was sure he would be happier in his next journey. it was palpably unsafe to suffer him to remain exposed to the temptation of an unexplored country; and as his friends and superiors at st. john's had just laden a vessel with fish for the italian market during lent, francie was despatched with her as supercargo, to look after the sales, in a land of which every footbreadth had been familiar to men for thousands of years, and in which it was supposed he would have no inducement to wander. francie, however, had read much about italy; and finding, on landing at leghorn, that he was within a short distance of pisa, he left ship and cargo to take care of themselves, and set out on foot to see the famous hanging tower, and the great marble cathedral. and tower and cathedral he did see: but it was meanwhile found that he was not quite suited for a supercargo; and he had shortly after to return to scotland, where his friends succeeded in establishing him in the capacity of clerk and overseer upon a small property in forfarshire, which was farmed by the proprietor on what was then the newly introduced modern system. he was acquainted, however, with the classical description of glammis castle, in the letters of the poet gray; and after visiting the castle, he set out to examine the ancient encampment at ardoch--the _lindum_ of the romans. finally, all hopes of getting him settled at a distance being given up by his friends, he had to fall back upon cromarty, where he was yet once more appointed to a clerkship. the establishment with which he was now connected was a large hempen manufactory; and it was his chief employment to register the quantities of hemp given out to the spinners, and the number of hanks of yarn into which they had converted it, when given in. he soon, however, began to take long walks; and the old women, with their yarn, would be often found accumulated, ere his return, by tens and dozens at his office-door. at length, after taking a very long walk indeed, for it stretched from near the opening to the head of the cromarty firth, a distance of about twenty miles, and included in its survey the antique tower of kinkell and the old castle of craighouse, he was relieved from the duties of his clerkship, and left to pursue his researches undisturbed, on a small annuity, the gift of his friends. he was considerably advanced in life ere i knew him, profoundly grave, and very taciturn, and, though he never discussed politics, a mighty reader of the newspapers. "oh! this is terrible," i have heard him exclaim, when on one occasion a snow storm had blocked up both the coast and the highland roads for a week together, and arrested the northward course of the mails,--"it is terrible to be left in utter ignorance of the public business of the country!" francie, whom every one called mr. ---- to his face, and always francie when his back was turned, chiefly because it was known he was punctilious on the point, and did not like the more familiar term, used in the winter evenings to be a regular member of the circle that met beside my uncle james's work-table. and, chiefly through the influence, in the first instance, of my uncles, i was permitted to visit him in his own room--a privilege enjoyed by scarce any one else--and even invited to borrow his books. his room--a dark and melancholy chamber, grey with dust--always contained a number of curious but not very rare things, which he had picked up in his walks--prettily coloured fungi--vegetable monstrosities of the commoner kind, such as "fause craws' nests," and flattened twigs of pine--and with these, as the representatives of another department of natural science, fragments of semi-transparent quartz or of glittering feldspar, and sheets of mica a little above the ordinary size. but the charm of the apartment lay in its books. francie was a book-fancier, and lacked only the necessary wealth to be in the possession of a very pretty collection. as it was, he had some curious volumes; among others, a first-edition copy of the "nineteen years' travels of william lithgow," with an ancient woodcut, representing the said william in the background, with his head brushing the skies, and, far in front, two of the tombs which covered the heroes of ilium, barely tall enough to reach half-way to his knee, and of the length, in proportion to the size of the traveller, of ordinary octavo volumes. he had black-letter books, too, on astrology, and on the planetary properties of vegetables; and an ancient book on medicine, that recommended as a cure for the toothache a bit of the jaw of a suicide, well triturated; and, as an infallible remedy for the falling-sickness, an ounce or two of the brains of a young man, carefully dried over the fire. better, however, than these, for at least my purpose, he had a tolerably complete collection of the british essayists, from addison to mackenzie, with the "essays" and "citizen of the world" of goldsmith; several interesting works of travels and voyages, translated from the french; and translations from the german, of lavater, zimmerman, and klopstock. he had a good many of the minor poets too; and i was enabled to cultivate, mainly from his collection, a tolerably adequate acquaintance with the wits of the reign of queen anne. poor francie was at bottom a kindly and honest man; but the more intimately one knew him, the more did the weakness and brokenness of his intellect appear. his mind was a labyrinth without a clue, in whose recesses there lay stored up a vast amount of book-knowledge, that could never be found when wanted, and was of no sort of use to himself, or any one else. i got sufficiently into his confidence to be informed, under the seal of strict secrecy, that he contemplated producing a great literary work, whose special character he had not quite determined, but which was to be begun a few years hence. and when death found him, at an age which did not fall far short of the allotted threescore and ten, the great unknown work was still an undefined idea, and had still to be begun. there were several other branches of my education going on at this time outside the pale of the school, in which, though i succeeded in amusing myself, i was no trifler. the shores of cromarty are strewed over with water-rolled fragments of the primary rocks, derived chiefly from the west during the ages of the boulder clay; and i soon learned to take a deep interest in sauntering over the various pebble-beds when shaken up by recent storms, and in learning to distinguish their numerous components. but i was sadly in want of a vocabulary; and as, according to cowper, "the growth of what is excellent is slow," it was not until long after that i bethought me of the obvious enough expedient of representing the various species of simple rocks, by certain numerals, and the compound ones by the numerals representative of each separate component, ranged, as in vulgar fractions, along a medial line, with the figures representative of the prevailing materials of the mass above, and those representative of the materials in less proportions below. though, however, wholly deficient in the signs proper to represent what i knew, i soon acquired a considerable quickness of eye in distinguishing the various kinds of rock, and tolerably definite conceptions of the generic character of the porphyries, granites, gneisses, quartz-rocks, clay-slates, and mica-schists, which everywhere strewed the beach. in the rocks of mechanical origin i was at this time much less interested; but in individual, as in general history, mineralogy almost always precedes geology. i was fortunate enough to discover, one happy morning, among the lumber and debris of old john feddes's dark room, an antique-fashioned hammer, which had belonged, my mother told me, to old john himself more than a hundred years before. it was an uncouth sort of implement, with a handle of strong black oak, and a short, compact head, square on the one face and oblong on the other. and though it dealt rather an obtuse blow, the temper was excellent, and the haft firmly set; and i went about with it, breaking into all manner of stones, with great perseverance and success. i found, in a large-grained granite, a few sheets of beautiful black mica, that, when split exceedingly thin, and pasted between slips of mica of the ordinary kind, made admirably-coloured eye-glasses, that converted the landscapes around into richly-toned drawings in sepia; and numerous crystals of garnet embedded in mica-schist, that were, i was sure, identical with the stones set in a little gold brooch, the property of my mother. to this last surmise, however, some of the neighbours to whom i showed my prize demurred. the stones in my mother's brooch were precious stones, they said; whereas what _i_ had found was merely a "stone upon the shore." my friend the cabinet-maker went so far as to say that the specimen was but a mass of plum-pudding stone, and its dark-coloured enclosures simply the currants; but then, on the other hand, uncle sandy took my view of the matter: the stone was not plum-pudding stone, he said: he had often seen plum-pudding stone in england, and knew it to be a sort of rough conglomerate of various components; whereas my stone was composed of a finely-grained silvery substance, and the crystals which it contained were, he was sure, gems like those in the brooch, and, so far as he could judge, real garnets. this was a great decision; and, much encouraged in consequence, i soon ascertained that garnets are by no means rare among the pebbles of the cromarty shore. nay, so mixed up are they with its sands even,--a consequence of the abundance of the mineral among the primary rocks of ross,--that after a heavy surf has beaten the exposed beach of the neighbouring hill, there may be found on it patches of comminuted garnet, from one to three square yards in extent, that resemble, at a little distance, pieces of crimson carpeting, and nearer at hand, sheets of crimson bead-work, and of which almost every point and particle is a gem. from some unexplained circumstance, connected apparently with the specific gravity of the substance, it separates in this style from the general mass, on coasts much beaten by the waves; but the garnets of these curious pavements, though so exceedingly abundant, are in every instance exceedingly minute. i never detected in them a fragment greatly larger than a pin-head; but it was always with much delight that i used to fling myself down on the shore beside some newly-discovered patch, and bethink me, as i passed my fingers along the larger grains, of the heaps of gems in aladdin's cavern, or of sinbad's valley of diamonds. the hill of cromarty formed at this time at once my true school and favourite play-ground; and if my master did wink at times harder than master ought, when i was playing truant among its woods or on its shores, it was, i believe, whether he thought so or no, all for the best. my uncle sandy had, as i have already said, been bred a cartwright; but finding, on his return, after his seven years' service on board a man-of-war, that the place had cartwrights enough for all the employment, he applied himself to the humble but not unremunerative profession of a sawyer, and used often to pitch his saw-pit, in the more genial seasons of the year, among the woods of the hill. i remember, he never failed setting it down in some pretty spot, sheltered from the prevailing winds under the lee of some fern-covered rising ground or some bosky thicket, and always in the near neighbourhood of a spring; and it used to be one of my most delightful exercises to find out for myself among the thick woods, in some holiday journey of exploration, the place of a newly-formed pit. with the saw-pit as my baseline of operations, and secure always of a share in uncle sandy's dinner, i used to make excursions of discovery on every side,--now among the thicker tracts of wood, which bore among the town-boys, from the twilight gloom that ever rested in their recesses, the name of "the dungeons;" and anon to the precipitous sea-shore, with its wild cliffs and caverns. the hill of cromarty is one of a chain belonging to the great ben nevis line of elevation; and, though it occurs in a sandstone district, is itself a huge primary mass, upheaved of old from the abyss, and composed chiefly of granitic gneiss and a red splintery horn-stone. it contains also numerous veins and beds of hornblend rock and chlorite-schist, and of a peculiar-looking granite, of which the quartz is white as milk, and the feldspar red as blood. when still wet by the receding tide, these veins and beds seem as if highly polished, and present a beautiful aspect; and it was always with great delight that i used to pick my way among them, hammer in hand, and fill my pockets with specimens. there was one locality which i in especial loved. no path runs the way. on the one side, an abrupt iron-tinged promontory, so remarkable for its human-like profile, that it seems part of a half-buried sphinx, protrudes into the deep green water. on the other--less prominent, for even at full tide the traveller can wind between its base and the sea--there rises a shattered and ruined precipice, seamed with blood-red ironstone, that retains on its surface the bright metallic gleam, and amid whose piles of loose and fractured rock one may still detect fragments of stalactite. the stalactite is all that remains of a spacious cavern, which once hollowed the precipice, but which, more than a hundred years before, had tumbled down during a thunder-storm, when filled with a flock of sheep, and penned up the poor creatures for ever. the space between these headlands forms an irregular crescent of great height, covered with wood a-top, and amid whose lichened crags, and on whose steep slopes, the hawthorn, and bramble, and wild rasp, and rock strawberry, take root, with many a scraggy shrub and sweet wild flower besides; while along its base lie huge blocks of green hornblend, on a rude pavement of granitic gneiss, traversed at one point, for many yards, by a broad vein of milk-white quartz. the quartz vein formed my central point of attraction in this wild paradise. the white stone, thickly traversed by threads of purple and red, is a beautiful though unworkable rock; and i soon ascertained that it is flanked by a vein of feldspar broader than itself, of a brick-red tint, and the red stone flanked, in turn, by a drab-coloured vein of the same mineral, in which there occur in great abundance masses of a homogeneous mica,--mica not existing in lamina, but, if i may use the term, as a sort of micaceous felt. it would almost seem as if some gigantic experimenter of the old world had set himself to separate into their simple mineral components the granitic rocks of the hill, and that the three parallel veins were the results of his labour. such, however, was not the sort of idea which they at this time suggested to me. i had read in sir walter raleigh's voyage to guiana, the poetic description of that upper country in which the knight's exploration of the river corale terminated, and where, amid lovely prospects of rich valleys, and wooded hills, and winding waters, almost every rock bore on its surface the yellow gleam of gold. true, according to the voyager, the precious metal was itself absent. but sir walter, on afterwards showing "some of the stones to a spaniard of the caraccas, was told by him they were _la madre de oro_, that is, the mother of gold, and that the mine itself was further in the ground." and though the quartz vein of the cromarty hill contained no metal more precious than iron, and but little even of that, it was, i felt sure, the "mother" of something very fine. as for silver, i was pretty certain i had found the "mother" of _it_, if not, indeed, the precious metal itself, in a cherty boulder, enclosing numerous cubes of rich galena; and occasional masses of iron pyrites gave, as i thought, large promise of gold. but though sometimes asked in humble irony, by the farm-servants who came to load their carts with sea-weed along the cromarty beach, whether i was "getting siller in the stanes," i was so unlucky as never to be able to answer their question in the affirmative. footnote: [ ] there may have been truth in the allegation; at least the hangman of inverness enjoyed, from time immemorial, a similar perquisite,--a peat out of every creel brought to the burgh market. chapter iv. "strange marble stones, here larger and there less, and of full various forms, which still increase in height and bulk by a continual drop. which upon each distilling from the top, and falling still exactly on the crown. there break themselves to mists, which, trickling down. crust into stone, and (but with leisure) swell the sides, and still advance the miracle."--charles cotton. it is low water in the firth of cromarty during stream tides, between six and seven o'clock in the evening; and my uncle sandy, in returning from his work at the close of the day, used not unfrequently, when, according to the phrase of the place, "there was a tide in the water," to strike down the hillside, and spend a quiet hour in the ebb. i delighted to accompany him on these occasions. there are professors of natural history that know less of living nature than was known by uncle sandy; and i deemed it no small matter to have all the various productions of the sea with which he was acquainted pointed out to me in these walks, and to be in possession of his many curious anecdotes regarding them. he was a skilful crab and lobster fisher, and knew every hole and cranny, along several miles of rocky shore, in which the creatures were accustomed to shelter, with not a few of their own peculiarities of character. contrary to the view taken by some of our naturalists, such as agassiz, who hold that the crab--a genus comparatively recent in its appearance in creation--is less embryotic in its character, and higher in its standing, than the more ancient lobster, my uncle regarded the lobster as a more highly developed and more intelligent animal than the crab. the hole in which the lobster lodges has almost always two openings, he has said, through one of which it sometimes contrives to escape when the other is stormed by the fisher; whereas the crab is usually content, like the "rat devoid of soul," with a hole of only one opening; and, besides, gets so angry in most cases with his assailant, as to become more bent on assault than escape, and so loses himself through sheer loss of temper. and yet the crab has, he used to add, some points of intelligence about him too. when, as sometimes happened, he got hold, in his dark narrow recess in the rock, of some luckless digit, my uncle showed me how that, after the first tremendous squeeze, he began always to experiment upon what he had got, by alternately slackening and straitening his grasp, as if to ascertain whether it had life in it, or was merely a piece of dead matter; and that the only way to escape him, on these trying occasions, was to let the finger lie passively between his nippers, as if it were a bit of stick or tangle; when, apparently deeming it such, he would be sure to let it go; whereas, on the least attempt to withdraw it, he would at once straiten his gripe, and not again relax it for mayhap half an hour. in dealing with the lobster, on the other hand, the fisher had to beware that he did not depend too much on the hold he had got of the creature, if it was merely a hold of one of the great claws. for a moment it would remain passive in his grasp; he would then be sensible of a slight tremor in the captured limb, and mayhap hear a slight crackle; and, _presto_, the captive would straightway be off like a dart through the deep-water hole, and only the limb remain in the fisher's hand. my uncle has, however, told me that lobsters do not always lose their limbs with the necessary judgment. they throw them off when suddenly frightened, without first waiting to consider whether the sacrifice of a pair of legs is the best mode of obviating the danger. on firing a musket immediately over a lobster just captured, he has seen it throw off both its great claws in the sudden extremity of its terror, just as a panic-struck soldier sometimes throws away his weapons. such, in kind, were the anecdotes of uncle sandy. he instructed me, too, how to find, amid thickets of laminaria and fuci, the nest of the lump-fish, and taught me to look well in its immediate neighbourhood for the male and female fish, especially for the male; and showed me further, that the hard-shelled spawn of this creature may, when well washed, be eaten raw, and forms at least as palatable a viand in that state as the imported caviare of russia and the caspian. there were instances in which the common crow acted as a sort of jackal to us in our lump-fish explorations. we would see him busied at the side of some fuci-covered pool, screaming and cawing as if engaged in combating an enemy; and, on going up to the place, we used to find the lump-fish he had killed fresh and entire, but divested of the eyes, which we found, as a matter of course, that the assailant, in order to make sure of victory, had taken the precaution of picking out at an early stage of the contest. nor was it with merely the edible that we busied ourselves on these journeys. the brilliant metallic _plumage_ of the sea mouse (_aphrodita_), steeped as in the dyes of the rainbow, excited our admiration time after time; and still higher wonder used to be awakened by a much rarer annelid, brown, and slender as a piece of rope-yarn, and from thirty to forty feet in length, which no one save my uncle had ever found along the cromarty shores, and which, when broken in two, as sometimes happened in the measuring, divided its vitality so equally between the pieces, that each was fitted, we could not doubt, though unable to repeat in the case the experiment of spallanzani, to set up as an independent existence, and carry on business for itself. the annelids, too, that form for themselves tubular dwellings built up of large grains of sand (_amphitrites_), always excited our interest. two hand-shaped tufts of golden-hued setæ--furnished, however, with greatly more than the typical number of fingers--rise from the shoulders of these creatures, and must, i suspect, be used as hands in the process of building; at least the hands of the most practised builder could not set stones with nicer skill than is exhibited by these worms in the setting of the grains which compose their cylindrical dwellings--dwellings that, from their form and structure, seem suited to remind the antiquary of the round towers of ireland, and, from the style of their masonry, of old cyclopean walls. even the mason-wasps and bees are greatly inferior workmen to these mason _amphitrites_. i was introduced also, in our ebb excursions, to the cuttle-fish and the sea-hare, and shown how the one, when pursued by an enemy, discharges a cloud of ink to conceal its retreat, and that the other darkens the water around it with a lovely purple pigment, which my uncle was pretty sure would make a rich dye, like that extracted of old by the tyrians from a whelk which he had often seen on the beach near alexandria. i learned, too, to cultivate an acquaintance with some two or three species of doris, that carry their arboraceous, tree-like lungs on their backs, as macduff's soldiers carried the boughs of birnam wood to the hill of dunsinane; and i soon acquired a sort of affection for certain shells, which bore, as i supposed, a more exotic aspect than their neighbours. among these were, _trochus zizyphinus_, with its flame-like markings of crimson, on a ground of paley-brown; _patella pellucida_, with its lustrous rays of vivid blue on its dark epidermis, that resemble the sparks of a firework breaking against a cloud; and, above all, _cypræa europea_, a not rare shell further to the north, but so little abundant in the firth of cromarty, as to render the live animal, when once or twice in a season i used to find it creeping on the laminaria at the extreme outer edge of the tide-line, with its wide orange mantle flowing liberally around it, somewhat of a prize. in short, the tract of sea-bottom laid dry by the ebb formed an admirable school, and uncle sandy an excellent teacher, under whom i was not in the least disposed to trifle; and when, long after, i learned to detect old-marine bottoms far out of sight of the sea--now amid the ancient forest-covered silurians of central england, and anon opening to the light on some hillside among the mountain limestones of our own country--i have felt how very much i owed to his instructions. his facts wanted a vocabulary adequately fitted to represent them; but though they "lacked a commodity of good names," they were all founded on careful observation, and possessed that first element of respectability--perfect originality: they were all acquired by himself. i owed more, however, to the habit of observation which he assisted me in forming, than even to his facts; and yet some of these were of high value. he has shown me, for instance, that an immense granitic boulder in the neighbourhood of the town, known for ages as the clach malloch, or cursed stone, stands so exactly in the line of low water, that the larger stream-tides of march and september lay dry its inner side, but never its outer one;--round the outer side there are always from two to four inches of water; and such had been the case for at least a hundred years before, in his father's and grandfather's days--evidence enough of itself, i have heard him say, that the relative levels of sea and land were not altering; though during the lapsed century the waves had so largely encroached on the low flat shores, that elderly men of his acquaintance, long since passed away, had actually held the plough when young where they had held the rudder when old. he used, too, to point out to me the effect of certain winds upon the tides. a strong hasty gale from the east, if coincident with a spring-tide, sent up the waves high upon the beach, and cut away whole roods of the soil; but the gales that usually kept larger tides from falling during ebb were prolonged gales from the west. a series of these, even when not very high, left not unfrequently from one to two feet water round the clach malloch, during stream-tides, that would otherwise have laid its bottom bare--a proof, he used to say, that the german ocean, from its want of breadth, could not be heaped up against our coasts to the same extent, by the violence of a very powerful east wind, as the atlantic by the force of a comparatively moderate westerly one. it is not improbable that the philosophy of the drift current, and of the apparently reactionary gulf stream, may be embodied in this simple remark. the woods on the lower slopes of the hill, when there was no access to the zones covered save at low ebb by the sea, furnished me with employment of another kind. i learned to look with interest on the workings of certain insects, and to understand some of at least their simpler instincts. the large diadem spider, which spins so strong a web, that, in pressing my way through the furze thickets, i could hear its white silken cords crack as they yielded before me, and which i found skilled, like an ancient magician, in the strange art of rendering itself invisible in the clearest light, was an especial favourite; though its great size, and the wild stories i had read about the bite of its cogener the tarantula, made me cultivate its acquaintance somewhat at a distance. often, however, have i stood beside its large web, when the creature occupied its place in the centre, and, touching it with a withered grass stalk, i have seen it sullenly swing on the lines "with its hands," and then shake them with a motion so rapid, that--like carathis, the mother of the caliph vathek, who, when her hour of doom had come, "glanced off in a rapid whirl, which rendered her invisible"--the eye failed to see either web or insect for minutes together. nothing appeals more powerfully to the youthful fancy than those coats, rings, and amulets of eastern lore, that conferred on their possessors the gift of invisibility. i learned, too, to take an especial interest in what, though they belong to a different family, are known as the water _spiders_; and have watched them speeding by fits and starts, like skaters on the ice, across the surface of some woodland spring or streamlet--fearless walkers on the waters, that, with true faith in the integrity of the implanted instinct, never made shipwreck in the eddy or sank in the pool. it is to these little creatures that wordsworth refers in one of his sonnets on sleep:-- "o sleep, thou art to me a fly that up and down himself doth shove upon a fretful rivulet; now _above_, now _on_ the water, vexed with mockery." as shown, however, to the poet himself on one occasion, somewhat to his discomfort, by assuredly no mean authority--mr. james wilson--the "vexed" "fly," though one of the hemipterous insects, never uses its wings, and so never gets "_above_" the water. among my other favourites were the splendid dragon-flies, the crimson-speckled burnet moths, and the small azure butterflies, that, when fluttering among delicate harebells and crimson-tipped daisies, used to suggest to me, long ere i became acquainted with the pretty figure of moore,[ ] or even ere the figure had been produced, the idea of flowers that had taken to flying. the wild honey bees, too, in their several species, had peculiar charms for me. there were the buff-coloured carders, that erected over their honey-jars domes of moss; the lapidary red-tipped bees, that built amid the recesses of ancient cairns, and in old dry stone walls, and were so invincibly brave in defending their homesteads, that they never gave up the quarrel till they died; and, above all, the yellow-zoned humble-bees, that lodged deep in the ground along the dry sides of grassy banks, and were usually wealthier in honey than any of their cogeners, and existed in larger communities. but the herd-boys of the parish, and the foxes of its woods and brakes, shared in my interest in the wild honey bees, and, in the pursuit of something else than knowledge, were ruthless robbers of their nests. i often observed, that the fox, with all his reputed shrewdness, is not particularly knowing on the subject of bees. he makes as dead a set on a wasp's nest as on that of the carder or humble-bee, and gets, i doubt not, heartily stung for his pains; for though, as shown by the marks of his teeth, left on fragments of the paper combs scattered about, he attempts eating the young wasps in the chrysalis state, the undevoured remains seem to argue that he is but little pleased with them as food. there were occasions, however, in which even the herd-boys met with only disappointment in their bee-hunting excursions; and in one notable instance, the result of the adventure used to be spoken of in school and elsewhere, under our breath and in secret, as something very horrible. a party of boys had stormed a humble-bees' nest on the side of the old chapel-brae, and, digging inwards along the narrow winding earth passage, they at length came to a grinning human skull, and saw the bees issuing thick from out a round hole at its base--the _foramen magnum_. the wise little workers had actually formed their nest within the hollow of the head, once occupied by the busy brain; and their spoilers, more scrupulous than samson of old, who seems to have enjoyed the meat brought forth out of the eater, and the sweetness extracted from the strong, left in very great consternation their honey all to themselves. one of my discoveries of this early period would have been deemed a not unimportant one by the geologist. among the woods of the hill, a short half-mile from the town, there is a morass of comparatively small extent, but considerable depth, which had been laid open by the bursting of a waterspout on the uplands, and in which the dark peaty chasm remained unclosed, though the event had happened ere my birth, until i had become old and curious enough thoroughly to explore it. it was a black miry ravine, some ten or twelve feet in depth. the bogs around waved thick with silvery willows of small size; but sticking out from the black sides of the ravine itself, and in some instances stretched across it from side to side, lay the decayed remains of huge giants of the vegetable world, that had flourished and died long ages ere, in at least our northern part of the island, the course of history had begun. there were oaks of enormous girth, into whose coal-black substance one could dig as easily with a pickaxe as one digs into a bank of clay; and at least one noble elm, which ran across the little stream that trickled, rather than flowed, along the bottom of the hollow, and which was in such a state of keeping, that i have scooped out of its trunk, with the unassisted hand, a way for the water. i have found in the ravine--which i learned very much to like as a scene of exploration, though i never failed to quit it sadly bemired--handfuls of hazel-nuts, of the ordinary size, but black as jet, with the cups of acorns, and with twigs of birch that still retained almost unchanged their silvery outer crust of bark, but whose ligneous interior existed as a mere pulp. i have even laid open, in layers of a sort of unctuous clay, resembling fuller's earth, leaves of oak, birch, and hazel, that had fluttered in the wind thousands of years before; and there was one happy day in which i succeeded in digging from out the very bottom of the excavation a huge fragment of an extraordinary-looking deer's horn. it was a broad, massive, strange-looking piece of bone, evidently old-fashioned in its type; and so i brought it home in triumph to uncle james, as the antiquary of the family, assured that he could tell me all about it. uncle james paused in the middle of his work; and, taking the horn in his hand, surveyed it leisurely on every side. "that is the horn, boy," he at length said, "of no deer that now lives in this country. we have the red deer, and the fallow deer, and the roe; and none of them have horns at all like that. i never saw an elk; but i am pretty sure this broad, plank-like horn can be none other than the horn of an elk." my uncle set aside his work; and, taking the horn in his hand, went out to the shop of a cabinet-maker in the neighbourhood, where there used to work from five to six journeymen. they all gathered round him to examine it, and agreed in the decision that it was an entirely different sort of horn from any borne by the existing deer of scotland, and that this surmise regarding it was probably just. and, apparently to enhance the marvel, a neighbour, who was lounging in the shop at the time, remarked, in a tone of sober gravity, that it had lain in the moss of the willows "for perhaps half a century." there was positive anger in the tone of my uncle's reply. "half a century, sir!!" he exclaimed; "was the elk a native of scotland half a century ago? there is no notice of the elk, sir, in british history. that horn must have lain in the moss of the willows for thousands of years!" "ah, ha, james, ah, ha," ejaculated the neighbour, with a sceptical shake of the head; but as neither he nor any one else dared meet my uncle on historical ground, the controversy took end with the ejaculation. i soon added to the horn of the elk that of a roe, and part of that of a red deer, found in the same ravine; and the neighbours, impressed by uncle james's view, used to bring strangers to look at them. at length, unhappily, a relation settled in the south, who had shown me kindness, took a fancy to them; and, smit by the charms of a gorgeous paint-box which he had just sent me, i made them over to him entire. they found their way to london, and were ultimately lodged in the collection of some obscure virtuoso, whose locality or name i have been unable to trace. the cromarty sutors have their two lines of caves--an ancient line hollowed by the waves many centuries ago, when the sea stood, in relation to the land, from fifteen to thirty feet higher along our shores than it does now; and a modern line, which the surf is still engaged in scooping out. many of the older caves are lined with stalactites, deposited by springs that, filtering through the cracks and fissures of the gneiss, find lime enough in their passage to acquire what is known as a _petrifying_, though, in reality, only an incrusting quality. and these stalactites, under the name of "white stones made by the water," formed of old--as in that cave of slains specially mentioned by buchanan and the chroniclers, and in those caverns of the peak so quaintly described by cotton--one of the grand marvels of the place. almost all the old gazetteers sufficiently copious in their details to mention cromarty at all, refer to its "dropping cave" as a marvellous marble-producing cavern; and this "dropping cave" is but one of many that look out upon the sea from the precipices of the southern sutor, in whose dark recesses the drops ever tinkle, and the stony ceilings ever grow. the wonder could not have been deemed a great or very rare one by a man like the late sir george mackenzie of coul, well known from his travels in iceland, and his experiments on the inflammability of the diamond; but it so happened, that sir george, curious to see the sort of stones to which the old gazetteers referred, made application to the minister of the parish for a set of specimens; and the minister straightway deputed the commission, which he believed to be not a difficult one, to one of his poorer parishioners, an old nailer, as a means of putting a few shillings in his way. it so happened, however, that the nailer had lost his wife by a sad accident, only a few weeks before; and the story went abroad that the poor woman was, as the townspeople expressed it, "coming back." she had been very suddenly hurried out of the world. when going down the quay after nightfall one evening, with a parcel of clean linen for a sailor, her relative, she had missed footing on the pier edge, and, half-brained, half-drowned, had been found in the morning, stone dead, at the bottom of the harbour. and now, as if pressed by some unsettled business, she used to be seen, it was said, hovering after nightfall about her old dwelling, or sauntering along the neighbouring street; nay, there were occasions, according to the general report, in which she had even exchanged words with some of the neighbours, little to their satisfaction. the words, however, seemed in every instance to have wonderfully little to do with the affairs of another world. i remember seeing the wife of a neighbour rush into my mother's one evening about this time, speechless with terror, and declare, after an awful pause, during which she had lain half-fainting in a chair, that she had just seen christy. she had been engaged, as the night was falling, but ere darkness had quite set in, in piling up a load of brushwood for fuel outside the door, when up started the spectre on the other side of the heap, attired in the ordinary work-day garb of the deceased, and, in a light and hurried tone, asked, as christy might have done ere the fatal accident, for a share of the brushwood. "give me some of that _hag_," said the ghost; "you have plenty--i have none." it was not known whether or no the nailer had seen the apparition; but it was pretty certain he believed in it; and as the "dropping cave" is both dark and solitary, and had forty years ago a bad name to boot--for the mermaid had been observed disporting in front of it even at mid-day, and lights and screams heard from it at nights--it must have been a rather formidable place to a man living in the momentary expectation of a visit from a dead wife. so far as could be ascertained--for the nailer himself was rather close in the matter--he had not entered the cave at all. he seemed, judging from the marks of scraping left along the sides for about two or three feet from the narrow opening, to have taken his stand outside, where the light was good, and the way of retreat clear, and to have raked outwards to him, as far as he could reach, all that stuck to the walls, including ropy slime and mouldy damp, but not one particle of stalactite. it was, of course, seen that his specimens would not suit sir george; and the minister, in the extremity of the case, applied to my uncles, though with some little unwillingness, as it was known that no remuneration for their trouble could be offered to them. my uncles were, however, delighted with the commission--it was all for the benefit of science; and, providing themselves with torches and a hammer, they set out for the caves. and i, of course, accompanied them--a very happy boy--armed, like themselves, with hammer and torch, and prepared devotedly to labour in behalf of science and sir george. i had never before seen the caves by torch-light; and though what i now witnessed did not quite come up to what i had read regarding the grotto of antiparos, or even the wonders of the peak, it was unquestionably both strange and fine. the celebrated dropping cave proved inferior--as is not unfrequently the case with the celebrated--to a cave almost entirely unknown, which opened among the rocks a little further to the east; and yet even _it_ had its interest. it widened, as one entered, into a twilight chamber, green with velvety mosses, that love the damp and the shade; and terminated in a range of crystalline wells, fed by the perpetual dropping, and hollowed in what seemed an altar-piece of the deposited marble. and above, and along the sides, there depended many a draped fold, and hung many a translucent icicle. the other cave, however, we found to be of much greater extent, and of more varied character. it is one of three caves of the old coast line, known as the doocot or pigeon caves, which open upon a piece of rocky beach, overhung by a rudely semicircular range of gloomy precipices. the points of the semicircle project on either side into deep water--into at least water so much deeper than the fall of ordinary neaps, that it is only during the ebb of stream tides that the place is accessible by land; and in each of these bold promontories--the terminal horns of the crescent--there is a cave of the present coast-line, deeply hollowed, in which the sea stands from ten to twelve feet in depth when the tide is at full, and in which the surf thunders, when gales blow hard from the stormy north-east, with the roar of whole parks of artillery. the cave in the western promontory, which bears among the townsfolk the name of the "puir wife's meal kist," has its roof drilled by two small perforations--the largest of them not a great deal wider than the blow-hole of a porpoise--that open externally among the cliffs above; and when, during storms from the sea, the huge waves come rolling ashore like green moving walls, there are certain times of the tide in which they shut up the mouth of the cave, and so compress the air within, that it rushes upwards through the openings, roaring in its escape as if ten whales were blowing at once, and rises from amid the crags overhead in two white jets of vapour, distinctly visible, to the height of from sixty to eighty feet. if there be critics who have deemed it one of the extravagances of goethe that he should have given life and motion, as in his famous witch-scene in "faust," to the hartz crags, they would do well to visit this bold headland during some winter tempest from the east, and find his description perfectly sober and true: "see the giant crags, oh ho! how they snort and how they blow!" within, at the bottom of the crescent, and where the tide never reaches when at the fullest, we found the large pigeon cave which we had come to explore, hollowed for about a hundred and fifty feet in the line of a fault. there runs across the opening the broken remains of a wall erected by some monopolizing proprietor of the neighbouring lands, with the intention of appropriating to himself the pigeons of the cavern; but his day, even at this time, had been long gone by, and the wall had sunk into a ruin. as we advanced, the cave caught the echoes of our footsteps, and a flock of pigeons, startled from their nests, came whizzing out, almost brushing us with their wings. the damp floor sounded hollow to the tread; we saw the green mossy sides, which close in the uncertain light, more than twenty feet overhead, furrowed by ridges of stalactites, that became whiter and purer as they retired from the vegetative influences; and marked that the last plant which appeared as we wended our way inwards was a minute green moss, about half an inch in length, which slanted outwards on the prominence of the sides, and overlay myriads of similar sprigs of moss, long before converted into stone, but which, faithful in death to the ruling law of their lives, still pointed, like the others, to the free air and the light. and then, in the deeper recesses of the cave, where the floor becomes covered with uneven sheets of stalagmite, and where long spear-like icicles and drapery-like foldings, pure as the marble of the sculptor, descend from above, or hang pendent over the sides, we found in abundance magnificent specimens for sir george. the entire expedition was one of wondrous interest; and i returned next day to school, big with description and narrative, to excite, by truths more marvellous than fiction, the curiosity of my class-fellows. i had previously introduced them to the marvels of the hill; and during our saturday half-holidays, some of them had accompanied me in my excursions to it. but it had failed, somehow, to catch their fancy. it was too solitary, and too far from home, and, as a scene of amusement, not at all equal to the town-links, where they could play at "shinty" and "french and english," almost within _hail_ of their parents' homesteads. the very tract along its flat, moory summit, over which, according to tradition, wallace had once driven before him in headlong rout a strong body of english, and which was actually mottled with sepulchral tumuli, still visible amid the heath, failed in any marked degree to engage them; and though they liked well enough to hear about the caves, they seemed to have no very great desire to see them. there was, however, one little fellow, who sat in the latin form--the member of a class lower and brighter than the heavy one, though it was not particularly bright either--who differed in this respect from all the others. though he was my junior by about a twelvemonth, and shorter by about half a head, he was a diligent boy in even the grammar school, in which boys were so rarely diligent, and, for his years, a thoroughly sensible one, without a grain of the dreamer in his composition. i succeeded, however, notwithstanding his sobriety, in infecting him thoroughly with my peculiar tastes, and learned to love him very much, partly because he doubled my amusements by sharing in them, and partly, i daresay--on the principle on which mahomet preferred his old wife to his young one--because "he believed in me." devoted to him as caliban in the _tempest_ to his friend trinculo-- "i showed him the best springs, i plucked him berries. and i with my long nails did dig him pig-nuts." his curiosity on this occasion was largely excited by my description of the doocot cave; and, setting out one morning to explore its wonders, armed with john feddes's hammer, in the benefits of which my friend was permitted liberally to share, we failed, for that day at least, in finding our way back. it was on a pleasant spring morning that, with my little curious friend beside me, i stood on the beach opposite the eastern promontory, that, with its stern granitic wall, bars access for ten days out of every fourteen to the wonders of the doocot; and saw it stretching provokingly out into the green water. it was hard to be disappointed, and the caves so near. the tide was a low neap, and if we wanted a passage dry-shod, it behoved us to wait for at least a week; but neither of us understood the philosophy of neap-tides at the period. i was quite sure i had got round at low water with my uncles not a great many days before, and we both inferred, that if we but succeeded in getting round now, it would be quite a pleasure to wait among the caves inside until such time as the fall of the tide should lay bare a passage for our return. a narrow and broken shelf runs along the promontory, on which, by the assistance of the naked toe and the toe-nail, it is just possible to creep. we succeeded in scrambling up to it; and then, crawling outwards on all fours--the precipice, as we proceeded, beetling more and more formidable from above, and the water becoming greener and deeper below--we reached the outer point of the promontory; and then doubling the cape on a still narrowing margin--the water, by a reverse process, becoming shallower and less green as we advanced inwards--we found the ledge terminating just where, after clearing the sea, it overhung the gravelly beach at an elevation of nearly ten feet. adown we both dropped, proud of our success; up splashed the rattling gravel as we fell; and for at least the whole coming week--though we were unaware of the extent of our good luck at the time--the marvels of the doocot cave might be regarded as solely and exclusively our own. for one short seven days--to borrow emphasis from the phraseology of carlyle--"they were our own, and no other man's." the first few hours were hours of sheer enjoyment the larger cave proved a mine of marvels; and we found a great deal additional to wonder at on the slopes beneath the precipices, and along the piece of rocky sea-beach in front. we succeeded in discovering for ourselves, in creeping, dwarf bushes, that told of the blighting influences of the sea-spray; the pale yellow honeysuckle, that we had never seen before, save in gardens and shrubberies; and on a deeply-shaded slope that leaned against one of the steeper precipices, we detected the sweet-scented woodroof of the flower-plot and parterre, with its pretty verticillate leaves, that become the more odoriferous the more they are crushed, and its white delicate flowers. there, too, immediately in the opening of the deeper cave, where a small stream came pattering in detached drops from the over-beetling precipice above, like the first drops of a heavy thunder-shower, we found the hot, bitter scurvy grass, with its minute cruciform flowers, which the great captain cook had used in his voyages; above all, _there_ were the caves with their pigeons--white, variegated, and blue--and their mysterious and gloomy depths, in which plants hardened into stone, and water became marble. in a short time we had broken off with our hammers whole pocketfuls of stalactites and petrified moss. there were little pools at the side of the cave, where we could see the work of congelation going on, as at the commencement of an october frost, when the cold north wind ruffles, and but barely ruffles, the surface of some mountain lochan or sluggish moorland stream, and shows the newly-formed needles of ice projecting mole-like from the shores into the water. so rapid was the course of deposition, that there were cases in which the sides of the hollows seemed growing almost in proportion as the water rose in them; the springs, lipping over, deposited their minute crystals on the edges; and the reservoirs deepened and became more capacious as their mounds were built up by this curious masonry. the long telescopic prospect of the sparkling sea, as viewed from the inner extremity of the cavern, while all around was dark as midnight--the sudden gleam of the sea-gull, seen for a moment from the recess, as it flitted past in the sunshine--the black heaving bulk of the grampus, as it threw up its slender jets of spray, and then, turning downwards, displayed its glossy back and vast angular fin--even the pigeons, as they shot whizzing by, one moment scarce visible in the gloom, the next radiant in the light--all acquired a new interest, from the peculiarity of the _setting_ in which we saw them. they formed a series of sun-gilt vignettes, framed in jet; and it was long ere we tired of seeing and admiring in them much of the strange and the beautiful. it did seem rather ominous, however, and perhaps somewhat supernatural to boot, that about an hour after noon, the tide, while there was yet a full fathom of water beneath the brow of the promontory, ceased to fall, and then, after a quarter of an hour's space, began actually to creep upwards on the beach. but just hoping that there might be some mistake in the matter, which the evening tide would scarce fail to rectify, we continued to amuse ourselves, and to hope on. hour after hour passed, lengthening as the shadows lengthened, and yet the tide still rose. the sun had sunk behind the precipices, and all was gloom along their bases, and double gloom in their caves; but their rugged brows still caught the red glare of evening. the flush rose higher and higher, chased by the shadows; and then, after lingering for a moment on their crests of honeysuckle and juniper, passed away, and the whole became sombre and grey. the sea-gull sprang upwards from where he had floated on the ripple, and hied him slowly away to his lodge in his deep-sea stack; the dusky cormorant flitted past, with heavier and more frequent stroke, to his whitened shelf high on the precipice; the pigeons came whizzing downwards from the uplands and the opposite land, and disappeared amid the gloom of their caves; every creature that had wings made use of them in speeding homewards; but neither my companion nor myself had any; and there was no possibility of getting home without them. we made desperate efforts to scale the precipices, and on two several occasions succeeded in reaching mid-way shelves among the crags, where the sparrowhawk and the raven build; but though we had climbed well enough to render our return a matter of bare possibility, there was no possibility whatever of getting farther up: the cliffs had never been scaled before, and they were not destined to be scaled now. and so, as the twilight deepened, and the precarious footing became every moment more doubtful and precarious still, we had just to give up in despair. "wouldn't care for myself," said the poor little fellow, my companion, bursting into tears, "if it were not for my mother; but what will my mother say?" "wouldn't care neither," said i, with a heavy heart; "but it's just back water, and we'll get out at twall." we retreated together into one of the shallower and drier caves, and, clearing a little spot of its rough stones, and then groping along the rocks for the dry grass that in the spring season hangs from them in withered tufts, we formed for ourselves a most uncomfortable bed, and lay down in one another's arms. for the last few hours mountainous piles of clouds had been rising dark and stormy in the sea-mouth: they had flared portentously in the setting sun, and had worn, with the decline of evening, almost every meteoric tint of anger, from fiery red to a sombre thundrous brown, and from sombre brown to doleful black. and we could now at least hear what they portended, though we could no longer see. the rising wind began to howl mournfully amid the cliffs, and the sea, hitherto so silent, to beat heavily against the shore, and to boom, like distress-guns, from the recesses of the two deep-sea caves. we could hear, too, the beating rain, now heavier, now lighter, as the gusts swelled or sank; and the intermittent patter of the streamlet over the deeper cave, now driving against the precipices, now descending heavily on the stones. my companion had only the real evils of the case to deal with, and so, the hardness of our bed and the coldness of the night considered, he slept tolerably well; but i was unlucky enough to have evils greatly worse than the real ones to annoy me. the corpse of a drowned seaman had been found on the beach about a month previous, some forty yards firm where we lay. the hands and feet, miserably contracted, and corrugated into deep folds at every joint, yet swollen to twice their proper size, had been bleached as white as pieces of alumed sheep-skin; and where the head should have been, there existed only a sad mass of rubbish. i had examined the body, as young people are apt to do, a great deal too curiously for my peace; and, though i had never done the poor nameless seaman any harm, i could not have suffered more from him during that melancholy night, had i been his murderer. sleeping or waking, he was continually before me. every time i dropped into a doze, he would come stalking up the beach from the spot where he had lain, with his stiff white fingers, that stuck out like eagle's toes, and his pale, broken pulp of a head, and attempt striking me; and then i would awaken with a start, cling to my companion, and remember that the drowned sailor had lain festering among the identical bunches of sea-weed that still rotted on the beach not a stone-cast away. the near neighbourhood of a score of living bandits would have inspired less horror than the recollection of that one dead seaman. towards midnight the sky cleared and the wind fell, and the moon, in her last quarter, rose red as a mass of heated iron out of the sea. we crept down, in the uncertain light, over the rough slippery crags, to ascertain whether the tide had not fallen sufficiently far to yield us a passage; but we found the waves chafing among the rocks just where the tide-line had rested twelve hours before, and a full fathom of sea enclasping the base of the promontory. a glimmering idea of the real nature of our situation at length crossed my mind. it was not imprisonment for a tide to which we had consigned ourselves, it was imprisonment for a week. there was little comfort in the thought, arising, as it did, amid the chills and terrors of a dreary midnight; and i looked wistfully on the sea as our only path of escape. there was a vessel crossing the wake of the moon at the time, scarce half a mile from the shore; and, assisted by my companion, i began to shout at the top of my lungs, in the hope of being heard by the sailors. we saw her dim bulk falling slowly athwart the red glittering belt of light that had rendered her visible, and then disappearing in the murky blackness, and just as we lost sight of her for ever, we could hear an indistinct sound mingling with the dash of the waves--the shout, in reply, of the startled helmsman. the vessel, as we afterwards learned, was a large stone-lighter, deeply laden, and unfurnished with a boat; nor were her crew at all sure that it would have been safe to attend to the midnight voice from amid the rocks, even had they had the means of communication with the shore. we waited on and on, however, now shouting by turns, and now shouting together; but there was no second reply; and at length, losing hope, we groped our way back to our comfortless bed, just as the tide had again turned on the beach, and the waves began to roll upwards higher and higher at every dash. as the moon rose and brightened, the dead seaman became less troublesome; and i had succeeded in dropping as soundly asleep as my companion, when we were both aroused by a loud shout. we started up and again crept downwards among the crags to the shore; and as we reached the sea the shout was repeated. it was that of at least a dozen harsh voices united. there was a brief pause, followed by another shout; and then two boats, strongly manned, shot round the western promontory, and the men, resting on their oars, turned towards the rock, and shouted yet again. the whole town had been alarmed by the intelligence that two little boys had straggled away in the morning to the rocks of the southern sutor, and had not found their way back. the precipices had been a scene of frightful accidents from time immemorial, and it was at once inferred that one other sad accident had been added to the number. true, there were cases remembered of people having been tide-bound in the doocot caves, and not much the worse in consequence; but as the caves were inaccessible during neaps, we could not, it was said, possibly be in them; and the sole remaining ground of hope was, that, as had happened once before, only one of the two had been killed, and that the survivor was lingering among the rocks, afraid to come home. and in this belief, when the moon rose and the surf fell, the two boats had been fitted out. it was late in the morning ere we reached cromarty, but a crowd on the beach awaited our arrival; and there were anxious-looking lights glancing in the windows, thick and manifold; nay, such was the interest elicited, that some enormously bad verses, in which the writer described the incident a few days after, became popular enough to be handed about in manuscript, and read at tea-parties by the _élite_ of the town. poor old miss bond, who kept the town boarding-school, got the piece nicely dressed up, somewhat on the principle upon which macpherson translated ossian; and at our first school-examination--proud and happy day for the author!--it was recited with vast applause, by one of her prettiest young ladies, before the assembled taste and fashion of cromarty. footnote: [ ] "the beautiful blue damsel flies, that fluttered round the jasmine steins, like wingéd flowers or flying gems." paradise and the peel. chapter v. "the wise shook their white aged heads o'er me, and said. of such materials wretched men were made."--byron. the report went abroad about this time, not without some foundation, that miss bond purposed patronizing me. the copy of my verses which had fallen into her hands--a genuine holograph--bore a-top a magnificent view of the doocot, in which horrid crags of burnt umber were perforated by yawning caverns of indian ink, and crested by a dense pine-forest of sap-green; while vast waves blue on the one side and green on the other, and bearing blotches of white lead a-top, rolled frightfully beneath. and miss bond had concluded, it was said, that such a genius as that evinced by the sketch and the "poem" for those sister arts of painting and poesy in which she herself excelled, should not be left to waste itself uncared for in the desert wilderness. she had published, shortly before, a work, in two slim volumes, entitled, "letters of a village governess"--a curious kind of medley, little amenable to the ordinary rules, but a genial book notwithstanding, with more heart than head about it; and not a few of the incidents which it related had the merit of being true. it was an unlucky merit for poor miss bond. she dated her book from fortrose, where she taught what was designated in the almanac as the boarding-school of the place, but which, according to miss bond's own description, was the school of the "village governess." and as her tales were found to be a kind of mosaics composed of droll bits of fact picked up in the neighbourhood, fortrose soon became considerably too hot for her. she had drawn, under the over-transparent guise of the niggardly mrs. flint, the skinflint wife of a "paper minister," who had ruined at one fell blow her best silk dress, and a dozen of good eggs to boot, by putting the eggs in her pocket when going out to a party, and then stumbling over a stone. and, of course, mrs. skinflint and the rev. mr. skinflint, with all their blood-relations, could not be other than greatly gratified to find the story furbished up in the printed form, and set in fun. there were other stories as imprudent and as amusing--of young ladies caught eavesdropping at their neighbours' windows; and of gentlemen, ill at ease in their families, sitting soaking among vulgar companions in the public-house; and so the authoress, shortly after the appearance of her work, ceased to be the village governess of fortrose, and became the village governess of cromarty. it was on this occasion that i saw, for the first time, with mingled admiration and awe, a human creature--not dead and gone, and merely a printed name--that had actually published a book. poor miss bond was a kindly sort of person, fond of children, and mightily beloved by them in turn; and, though keenly alive to the ludicrous, without a grain of malice in her. i remember how, about this time, when, assisted by some three or four boys more, i had succeeded in building a huge house, full four feet long and three feet high, that contained us all, and a fire, and a great deal of smoke to boot, miss bond the authoress came, and looked in upon us, first through the little door, and then down through the chimney, and gave us kind words, and seemed to enjoy our enjoyment very much; and how we all deemed her visit one of the greatest events that could possibly have taken place. she had been intimate with the parents of sir walter scott; and, on the appearance of sir walter's first publication, the "minstrelsy of the scottish border," she had taken a fit of enthusiasm, and written to him; and, when in the cold paroxysm, and inclined to think she had done something foolish, had received from sir walter, then mr. scott, a characteristically warm-hearted reply. she experienced much kindness at his hands ever after; and when she herself became an author, she dedicated her book to him. he now and then procured boarders for her; and when, after leaving cromarty for edinburgh, she opened a school in the latter place, and got on with but indifferent success, sir walter--though straggling with his own difficulties at the time--sent her an enclosure of ten pounds, to scare, as he said in his note, "the wolf from the door." but miss bond, like the original of his own jeanie deans, was a "proud bodie;" and the ten pounds were returned, with the intimation that the wolf had not yet come to the door. poor lady! i suspect he came to the door at last. like many other writers of books, her voyage through life skirted, for the greater part of the way, the bleak lee-shore of necessity; and it cost her not a little skilful steering at times to give the strand a respectable offing. and in her solitary old age, she seemed to have got fairly aground. there was an attempt made by some of her former pupils to raise money enough to purchase for her a small annuity; but when the design was in progress, i heard of her death. she illustrated in her life the remark recorded by herself in her "letters," as made by a humble friend:--"it's no an easy thing, mem, for a woman to go through the world _without a head_," _i.e._, single and unprotected. from some unexplained cause, miss bond's patronage never reached me. i am sure the good lady intended giving me lessons in both drawing and composition; for she had said it, and her heart was a kind one; but then her time was too much occupied to admit of her devoting an occasional hour to myself alone; and as for introducing me to her young-lady classes, in my rough garments, ever greatly improved the wrong way by my explorations in the ebb and the peat-moss, and frayed, at times, beyond even my mother's ability of repair, by warping to the tops of great trees, and by feats as a cragsman--that would have been a piece of jack-cadeism, on which, then or now, no village governess could have ventured. and so i was left to get on in verse and picture-making quite in the wild way, without care or culture. my schoolfellows liked my stories well enough--better at least, on most occasions, than they did the lessons of the master; but, beyond the common ground of enjoyment which these extempore compositions furnished to both the "sennachie" and his auditors, our tracts of amusement lay widely apart. i disliked, as i have said, the yearly cock-fight--found no pleasure in cat-killing, or in teasing at nights, or on the street, the cross-tempered, half-witted _eccentrics_ of the village--usually kept aloof from the ordinary play-grounds, and very rarely mingled in the old hereditary games. on the other hand, with the exception of my little friend of the cave, who, even after that disastrous incident, evinced a tendency to trust and follow me as implicitly as before, my schoolmates cared as little for my amusements as i did for theirs; and, having the majority on their side, they of course voted mine to be the foolish ones. and certainly a run of ill-luck followed me in my sports about this time, that did give some show of reason to their decision. in the course of my book-hunting, i had fallen in with two old-fashioned military treatises, part of the small library of a retired officer lately deceased, of which the one entitled the "military medley," discussed the whole art of marshalling troops, and contained numerous plans, neatly coloured, of battalions drawn up in all possible forms, to meet all possible exigencies; while the other, which also abounded in prints, treated of the noble science of fortification according to the system of vauban. i poured over both works with much perseverance; and, regarding them as admirable toy-books, set myself to construct, on a very small scale, some of the toys with which they specially dealt. the sea-shore in the immediate neighbourhood of the town appeared to my inexperienced eye an excellent field for the carrying on of a campaign. the sea-sand i found quite coherent enough, when still moistened by the waters of the receding tide, to stand up in the form of towers and bastions, and long lines of rampart; and there was one of the commonest of the littorinidæ--_littorina litoralis_, that in one of its varieties is of a rich yellow colour, and in another of a bluish-green tint--which supplied me with soldiers enough to execute all the evolutions figured and described in the "medley." the warmly-hued yellow shells represented britons in their scarlet--the more dingy ones, the french in their uniforms of dirty blue; well-selected specimens of _purpura lapillus_, just tipped on their backs with a speck of paint, blue or red, from my box, made capital dragoons; while a few dozens of the slender pyramidal shells of _turritella communis_ formed complete parks of artillery. with such unlimited stores of the _matériel_ of war at my command, i was enabled, more fortunate than uncle toby of old, to fight battles and conduct retreats, assault and defend, build up fortifications, and then batter them down again, at no expense at all; and the only drawback on such a vast amount of advantage that i could at first perceive consisted in the circumstance, that the shore was exceedingly open to observation, and that my new amusements, when surveyed at a little distance, did greatly resemble those of the very young children of the place, who used to repair to the same arenaceous banks and shingle-beds, to bake dirt-pies in the sand, or range lines of shells on little shelves of stone, imitative of the crockery cupboard at home. not only my school-fellows, but also some of their parents, evidently arrived at the conclusion that the two sets of amusements--mine and those of the little children--were identical; for the elder folk said, that "in their time, poor francie had been such another boy, and every one saw what he had come to;" while the younger, more energetic in their manifestations, and more intolerant of folly, have even paused in their games of marbles, or ceased spinning their tops, to hoot at me from a safe distance. but the campaign went on; and i solaced myself by reflecting, that neither the big folk nor the little folk could bring a battalion of troops across a bridge of boats in the face of an enemy, or knew that a regular fortification could be constructed on only a regular polygon. i at length discovered however, that as a sea-shore is always a sloping plane, and the cromarty beach, in particular, a plane of a rather steep slope, it afforded no proper site for a fortress fitted to stand a protracted siege, seeing that, fortify the place as i might, it could be easily commanded by batteries raised on the higher side. and so fixing upon a grassy knoll among the woods, in the immediate neighbourhood of a scaur of boulder clay, capped by a thick stratum of sand, as a much better scene of operations, i took possession of the knoll somewhat irregularly; and carrying to it large quantities of sand from the scaur, converted it into the site of a magnificent stronghold. first i erected an ancient castle, consisting of four towers built on a rectangular base, and connected by straight curtains embrasured a-top. i then surrounded the castle by outworks in the modern style, consisting of greatly lower curtains than the ancient ones, flanked by numerous bastions, and bristling with cannon of huge calibre, made of the jointed stalks of the hemlock; while, in advance of these, i laid down ravelins, horn-works, and tenailles. i was vastly delighted with my work: it would, i was sure, be no easy matter to reduce such a fortress; but observing an eminence in the immediate neighbourhood which could, i thought, be occupied by a rather annoying battery, i was deliberating how i might best take possession of it by a redoubt, when out started, from behind a tree, the factor of the property on which i was trespassing, and rated me soundly for spoiling the grass in a manner so wantonly mischievous. horn-work and half-moon, tower and bastion, proved of no manner of effect in repelling an attack of a kind so little anticipated. i did think that the factor, who was not only an intelligent man, but had also seen much service in his day on the town links, as the holder of a commission in the cromarty volunteers, might have perceived that i was labouring on scientific principles, and so deem me worthy of some tolerance on that account; but i suppose he did not; though, to be sure, his scold died out good-naturedly enough in the end, and i saw him laugh as he turned away. but so it was, that in the extremity of my mortification i gave up generalship and bastion-building for the time; though, alas! my next amusement must have worn in the eyes of my youthful compeers as suspicious an aspect as either. my friend of the cave had lent me what i had never seen before--a fine quarto edition of anson's voyages, containing the original prints (my father's copy had only the maps); among the others, mr. brett's elaborate delineation of that strangest of vessels, a proa of the ladrone islands. i was much struck by the singularity of the construction of a barque that, while its head and stern were exactly alike, had sides that totally differed from each other, and that, with the wind upon the beam, outsailed, it was said, all other vessels in the world; and having the command of the little shop in which my uncle sandy made occasional carts and wheelbarrows when unemployed abroad, i set myself to construct a miniature proa, on the model given in the print, and succeeded in fabricating a very extraordinary proa indeed. while its lee side was perpendicular as a wall, its windward one, to which there was an outrigger attached, resembled that of a flat-bottomed boat; head and stern were exactly alike, so as to fit each for performing in turn the part of either; a moveable yard, which supported the sail, had to be shifted towards the end converted into the stern for the time, at each tack; while the sail itself--a most uncouth-looking thing--formed a scalene triangle. such was the vessel--some eighteen inches long or so--with which i startled from their propriety the mimic navigators of a horse-pond in the neighbourhood--all very masterly critics in all sorts of barques and barges known on the scottish coast. according to campbell, "'twas a thing beyond description wretched: such a wherry, perhaps, ne'er ventured on a pond, or crossed a ferry." and well did my fellows appreciate its extreme ludicrousness. it was certainly rash to "venture" it on this especial "pond;" for, greatly to the damage of the rigging, it was fairly pelted off, and i was sent to test elsewhere its sailing qualities, which were, as i ascertained, not very remarkable after all. and thus, after a manner so unworthy, were my essays in strategy and barque-building received by a censorious age, that judged ere it knew. were i sentimental, which lucidly i am not, i might well exclaim, in the very vein of rousseau, alas! it has been ever the misfortune of my life that, save by a few friends, i have never been understood! i was evidently out-francieing francie; and the parents of my young friend, who saw that i had acquired considerable influence over him, and were afraid lest i should make another francie of _him_, had become naturally enough desirous to break off our intimacy, when there occurred an unlucky accident, which served materially to assist them in the design. my friend's father was the master of a large trading smack, which, in war times, carried a few twelve-pounders, and was furnished with a small magazine of powder and shot; and my friend having secured for himself from the general stock, through the connivance of the ship-boy, an entire cannon cartridge, containing some two or three pounds of gunpowder, i was, of course, let into the secret, and invited to share in the sport and the spoil we had a glorious day together in his mother's garden: never before did such magnificent volcanoes break forth out of mole-hills, or were plots of daisies and violets so ruthlessly scorched and torn by the explosion of deep laid mines; and though a few mishaps did happen to over-forward fingers, and to eye-brows that were in the way, our amusements passed off innocuously on the whole, and evening saw nearly the half of our precious store unexhausted. it was garnered up by my friend in an unsuspected corner of the garret in which he slept, and would have been safe, had he not been seized, when going to bed, with a yearning desire to survey his treasure by candle-light; when an unlucky spark from the flame exploded the whole. he was so sadly burnt about the face and eyes as to be blind for several days after; but, amid smoke and confusion, he gallantly bolted his garret-door, and, while the inmates of the household, startled by the shock and the noise, came rushing up stairs, sturdily refused to let any of them in. volumes of gunpowder reek issued from every crack and cranny, and his mother and sisters were prodigiously alarmed. at length, however, he capitulated--terms unknown; and i, next morning, heard with horror and dismay of the accident. it had been matter of agreement between us on the previous day, mainly in order to screen the fine fellow of a ship-boy, that i should be regarded as the owner of the powder; but here was a consequence on which i had not calculated; and the strong desire to see my poor friend was dashed by the dread of being held responsible by his parents and sisters for the accident. and so, more than a week elapsed ere i could muster up courage enough to visit him. i was coldly received by his mother, and, what vexed me to the heart, coldly received by himself; and suspecting that he had been making an ungenerous use of our late treaty, i took leave in high dudgeon, and came away. my suspicions, however, wronged him: he had stoutly denied, as i afterwards learned, that i had any share in the powder; but his friends deeming the opportunity a good one for breaking with me, had compelled him, very unwillingly, and after much resistance, to give me up. and from this period more than two years elapsed, though our hearts beat quick and high every time we accidentally met, ere we exchanged a single word. on one occasion, however, shortly after the accident, we did exchange letters. i wrote to him from the school-form, when, of course, i ought to have been engaged with my tasks, a stately epistle, in the style of the billets in the "female quixote," which began, i remember, as follows:--"i once thought i had a friend whom i could rely upon; but experience tells me he was only nominal. for, had he been a real friend, no accident could have interfered with, or arbitrary command annihilated, his affection," &c., &c. as i was rather an indifferent scribe at the time, one of the lads, known as the "copperplate writers" of the class, made for me a fair copy of my lucubration, full of all manner of elegant dashes, and in which the spelling of every word was scrupulously tested by the dictionary. and, in due course, i received a carefully engrossed note in reply, of which the manual portion was performed by my old companion, but the composition, as he afterwards told me, elaborated by some one else. it assured me he was still my friend, but that there were "certain circumstances" which would prevent us from meeting for the future on our old terms. we were, however, destined to meet pretty often in the future, notwithstanding; and narrowly missed going to the bottom together many years after, in the floating manse, grown infirm in her nether parts at the time, when he was the outed minister of small isles, and i editor of the _witness_ newspaper. i had a maternal aunt long settled in the highlands of sutherland, who was so much older than her sister, my mother, that, when nursing her eldest boy, she had, when on a visit to the low country, assisted also in nursing her. the boy had shot up into a very clever lad, who, having gone to seek his fortune in the south, rose, through the several degrees of clerkship in a mercantile firm, to be the head of a commercial house of his own, which, though ultimately unsuccessful, seemed for some four or five years to be in a fair way of thriving. for about three of these the portion of the profits which fell to my cousin's share did not fall short of fifteen hundred pounds per annum; and on visiting his parents in their highland home in the heyday of his prosperity, after an absence of years, it was found that he had a great many friends in his native district on whom he had not calculated, and of a class that had not been greatly in the habit of visiting his mother's cottage, but who now came to lunch, and dine, and take their wine with him, and who seemed to value and admire him very much. my aunt, who was little accustomed to receive high company, and found herself, like martha of old, "cumbered about much serving," urgently besought my mother, who was young and active at the time, to visit and assist her; and, infinitely to my delight, i was included in the invitation. the place was not much above thirty miles from cromarty; but then it was in the _true_ highlands, which i had never before seen, save on the distant horizon; and, to a boy who had to walk all the way, even thirty miles, in an age when railways were not, and ere even mail gigs had penetrated so far, represented a journey of no inconsiderable distance. my mother, though rather a delicate-looking woman, walked remarkably well; and early on the evening of the second day, we reached together my aunt's cottage, in the ancient barony of gruids. it was a low, long, dingy edifice of turf, four or five rooms in length, but only one in height, that, lying along a gentle acclivity, somewhat resembled at a distance a huge black snail creeping up the hill. as the lower apartment was occupied by my uncle's half-dozen milk-cows, the declination of the floor, consequent on the nature of the site, proved of signal importance, from the free drainage which it secured; the second apartment, reckoning upwards, which was of considerable size, formed the sitting-room of the family, and had, in the old highland style, its fire full in the middle of the floor, without back or sides; so that, like a bonfire kindled in the open air, all the inmates could sit around it in a wide circle--the women invariably ranged on the one side, and the men on the other; the apartment beyond was partitioned into small and very dark bed-rooms; while, further on still, there was a closet with a little window in it, which was assigned to my mother and me; and beyond all lay what was emphatically "the room," as it was built of stone, and had both window and chimney, with chairs, and table, and chest of drawers, a large box-bed, and a small but well-filled bookcase. and "the room" was, of course, for the time, my cousin the merchant's apartment,--his dormitory at night, and the hospitable refectory in which he entertained his friends by day. my aunt's family was one of solid worth. her husband--a compactly-built, stout-limbed, elderly highlander, rather below the middle size, of grave and somewhat melancholy aspect, but in reality of a temperament rather cheerful than otherwise--had been somewhat wild in his young days. he had been a good shot and a skilful angler, and had danced at bridals, and, as was common in the highlands at the time, at lykewakes; nay, on one occasion he had succeeded in inducing a new-made widow to take the floor in a strathspey, beside her husband's corpse when every one else had failed to bring her up, by roguishly remarking, in her hearing, that whoever else might have refused to dance at poor donald's death wake, he little thought it would have been she. but a great change had passed over him; and he was now a staid, thoughtful, god-fearing man, much respected in the barony for honest worth and quiet unobtrusive consistency of character. his wife had been brought, at an early age, under the influence of donald roy's ring, and had, like her mother, been the means of introducing the vitalities of religion into her household. they had two other sons besides the merchant--both well-built, robust men, somewhat taller than their father, and of such character, that one of my cromarty cousins, in making out his way, by dint of frequent and sedulous inquiry, to their dwelling, found the general verdict of the district embodied in the very bad english of a poor old woman, who, after doing her best to direct him, certified her knowledge of the household by remarking, "it's a goot mistress;--it's a goot maister;--it's a goot, goot two lads." the elder of the two brothers superintended, and partly wrought, his father's little farm; for the father himself found employment enough in acting as a sort of humble factor for the proprietor of the barony, who lived at a distance, and had no dwelling upon the land. the younger was a mason and slater, and was usually employed, in the working seasons, at a distance; but in winter, and, on this occasion, for a few weeks during the visit of his brother the merchant, he resided with his father. both were men of marked individuality of character. the elder, hugh, was an ingenious, self-taught mechanic, who used in the long winter evenings to fashion a number of curious little articles by the fireside--among the rest, highland snuff-mulls, with which he supplied all his friends; and he was at this time engaged in building for his father a highland barn, and, to vary the work, fabricating for him a highland plough. the younger, george, who had wrought for a few years at his trade in the south of scotland, was a great reader, wrote very tolerable prose, and verse which, if not poetry, to which he made no pretensions, was at least quaintly-turned rhyme. he had, besides, a competent knowledge of geometry, and was skilled in architectural drawing; and--strange accomplishment for a celt--he was an adept in the noble science of self-defence. but george never sought out quarrels; and such was his amount of bone and muscle, and such the expression of manly resolution stamped on his countenance, that they never came in his way unsought. at the close of the day, when the members of the household had assembled in a wide circle round the fire, my uncle "took the book," and i witnessed, for the first time, family-worship conducted in gaelic. there was, i found, an interesting peculiarity in one portion of the services which he conducted. he was, as i have said, an elderly man, and had worshipped in his family ere dr. stewart's gaelic translation of the scriptures had been introduced into the county; and as he possessed in those days only the english bible, while his domestics understood only gaelic, he had to acquire the art, not uncommon in sutherland at the time, of translating the english chapter for them, as he read, into their native tongue; and this he had learned to do with such ready fluency, that no one could have guessed it to be other than a gaelic work from which he was reading. nor had the introduction of dr. stewart's translation rendered the practice obsolete in his household. his gaelic was _sutherlandshire_ gaelic, whereas that of dr. stewart was argyleshire gaelic. his family understood his rendering better, in consequence, than that of the doctor; and so he continued to translate from his english bible _ad aperturam libri_, many years after the gaelic edition had been spread over the country. the concluding evening prayer was one of great solemnity and unction. i was unacquainted with the language in which it was couched; but it was impossible to avoid being struck, notwithstanding, with its wrestling earnestness and fervour. the man who poured it forth evidently believed there was an unseen ear open to it, and an all-seeing presence in the place, before whom every secret thought lay exposed. the entire scene was a deeply impressive one; and when i saw, in witnessing the celebration of high mass in a popish cathedral many years after, the altar suddenly enveloped in a dim and picturesque obscurity, amid which the curling smoke of the incense ascended, and heard the musically-modulated prayer sounding in the distance from within the screen, my thoughts reverted to the rude highland cottage, where, amid solemnities not theatric, the red umbry light of the fire fell with uncertain glimmer upon dark walls, and bare black rafters, and kneeling forms, and a pale expanse of dense smoke, that, filling the upper portion of the roof, overhung the floor like a ceiling, and there arose amid the gloom the sounds of prayer truly god-directed, and poured out from the depths of the heart; and i felt that the stoled priest of the cathedral was merely an artist, though a skilful one, but that in the "priest and father" of the cottage there were the truth and reality from which the artist drew. no bolt was drawn across the outer door as we retired for the night. the philosophic biot, when employed with his experiments on the second pendulum, resided for several months in one of the smaller shetland islands; and, fresh from the troubles of france--his imagination bearing about with it, if i may so speak, the stains of the guillotine--the state of trustful security in which he found the simple inhabitants filled him with astonishment. "here, during the twenty-five years in which europe has been devouring herself," he exclaimed, "the door of the house i inhabit has remained open day and night." the interior of sutherland was at the time of my visit in a similar condition. the door of my uncle's cottage, unfurnished with lock or bar, opened, like that of the hermit in the ballad, with a latch; but, unlike that of the hermit, it was not because there were no stores within to demand the care of the master, but because at that comparatively recent period the crime of theft was unknown in the district. i rose early next morning, when the dew was yet heavy on grass and lichen, curious to explore a locality so new to me. the tract, though a primary one, forms one of the tamer gneiss districts of scotland; and i found the nearer hills comparatively low and confluent, and the broad valley in which lay my uncle's cottage, flat, open, and unpromising. still there were a few points to engage me; and the more i attached myself to them, the more did their interest grow. the western slopes of the valley are mottled by grassy tomhans--the moraines of some ancient glacier, around and over which there rose, at this period, a low widely-spreading wood of birch, hazel, and mountain ash--of hazel, with its nuts fast filling at the time, and of mountain ash, with its berries glowing bright in orange and scarlet. in looking adown the hollow, a group of the green tomhans might be seen relieved against the blue hills of ross; in looking upwards, a solitary birch-covered hillock of similar origin, but larger proportions, stood strongly out against the calm waters of loch shin and the purple peaks of the distant ben-hope. in the bottom of the valley, close beside my uncle's cottage, i marked several low swellings of the rock beneath, rising above the general level; and, ranged along these, there were groups of what seemed to be huge boulder stones, save that they were less rounded and water-worn than ordinary boulders, and were, what groups of boulders rarely are, all of one quality. and on examination, i ascertained that some of their number, which stood up like broken obelisks, tall, and comparatively narrow of base, and all hoary with moss and lichen, were actually still connected with the mass of rock below. they were the wasted upper portions of vast dikes and veins of a grey, large-grained syenite, that traverse the fundamental gneiss of the valley, and which i found veined, in turn, by threads and seams of a white quartz, abounding in drusy cavities, thickly lined along their sides with sprig crystals. never had i seen such lovely crystals on the shores of cromarty, or anywhere else. they were clear and transparent as the purest spring water, furnished each with six sides, and sharpened a-top into six facets. borrowing one of cousin george's hammers, i soon filled a little box with these gems, which even my mother and aunt were content to admire, as what of old used, they said, to be called bristol diamonds, and set in silver brooches and sleeve buttons. further, within less than a hundred yards of the cottage, i found a lively little stream, brown, but clear as a cairngorm of the purest water, and abounding, as i soon ascertained, in trout, lively and little like itself, and gaily speckled with scarlet. it wound through a flat, dank meadow, never disturbed by the plough; for it had been a burying-ground of old, and flat undressed stones lay thick amid the rank grass. and in the lower corner, where the old turf-wall had sunk into an inconspicuous mound, there stood a mighty tree, all solitary, for its fellows had long before disappeared, and so hollow-hearted in its corrupt old age, that though it still threw out every season a mighty expanse of foliage, i was able to creep into a little chamber in its trunk, from which i could look out through circular openings where boughs once had been, and listen, when a sudden shower came sweeping down the glen, to the pattering of the rain-drops amid the leaves. the valley of the gruids was perhaps not one of the finest or most beautiful of highland valleys, but it was a very admirable place after all; and amid its woods, and its rocks, and its tomhans, and at the side of its little trouting stream, the weeks passed delightfully away. my cousin william, the merchant, had, as i have said, many guests; but they were all too grand to take any notice of me. there was, however, one delightful man, who was said to know a great deal about rocks and stones, that, having heard of my fine large crystals, desired to see both them and the boy who had found them; and i was admitted to hear him talk about granites, and marbles, and metallic veins, and the gems that lie hid among the mountains in nooks and crannies. i am afraid i would not now deem him a very accomplished mineralogist: i remember enough of his conversation to conclude that he knew but little, and that little not very correctly: but not before werner or hutton could i have bowed down with a profounder reverence. he spoke of the marbles of assynt--of the petrifactions of helmsdale and brora--of shells and plants embedded in solid rocks, and of forest trees converted into stone; and my ears drank in knowledge eagerly, as those of the queen of sheba of old when she listened to solomon. but all too soon did the conversation change. my cousin was mighty in gaelic etymology, and so was the mineralogist; and while my cousin held that the name of the barony of gruids was derived from the great hollow tree, the mineralogist was quite as certain that it was derived from its syenite, or, as he termed it, its _granite_, which resembled, he remarked, from the whiteness of its feldspar, a piece of curd. _gruids_, said the one, means the place of the great tree; _gruids_, said the other, means the place of the curdled stone. i do not remember how they settled the controversy; but it terminated, by an easy transition, in a discussion respecting the authenticity of ossian--a subject on which they were both perfectly agreed. there could exist no manner of doubt regarding the fact that the poems given to the world by macpherson had been sung in the highlands by ossian, the son of fingal, more than fourteen hundred years before. my cousin was a devoted member of the highland society; and the highland society, in these days, was very much engaged in ascertaining the right cut of the philabeg, and in determining the chronology and true sequence of events in the ossianic age. happiness perfect and entire is, it is said, not to be enjoyed in this sublunary state; and even in the gruids, where there was so much to be seen, heard, and found out, and where i was separated by more than thirty miles from my latin--for i had brought none of it from home with me--this same ossianic controversy rose like a highland fog on my horizon, to chill and darken my hours of enjoyment. my cousin possessed everything that had been written on the subject, including a considerable amount of manuscript of his own composition; and as uncle james had inspired him with the belief that i could master anything to which in good earnest i set my mind, he had determined that it should be no fault of his if i did not become mighty in the controversy regarding the authenticity of ossian. this was awful. i liked blair's dissertation well enough, nor did i greatly quarrel with that of kames; and as for sir walter's critique in the _edinburgh_, on the opposite side, i thought it not only thoroughly sensible, but, as it furnished me with arguments against the others, deeply interesting to boot. but then there succeeded a vast ocean of dissertation, emitted by highland gentlemen and their friends, as the dragon in the apocalypse emitted the great flood which the earth swallowed up; and, when once fairly embarked upon it, i could see no shore and find no bottom. and so at length, though very unwillingly--for my cousin was very kind--i fairly mutinied and struck work, just as he had begun to propose that, after mastering the authenticity controversy, i should set myself to acquire gaelic, in order that i might be able to read ossian in the original. my cousin was not well pleased; but i did not choose to aggravate the case by giving expression to the suspicion which, instead of lessening, has rather grown upon me since, that as i possessed an english copy of the poems, i had read the true ossian in the original already. with cousin george, however, who, though strong on the authenticity side, liked a joke rather better than he did ossian, i was more free; and to him i ventured to designate his brother's fine gaelic copy of the poems, with a superb head of the ancient bard affixed, as "the poems of ossian in gaelic, translated from the original english by their author." george looked grim, and called me infidel, and then laughed, and said he would tell his brother. but he didn't; and as i really liked the poems, especially "_temora_" and some of the smaller pieces, and could read them with more real pleasure than the greater part of the highlanders who believed in them, i did not wholly lose credit with my cousin the merchant. he even promised to present me with a finely bound edition of the "elegant extracts," in three bulky octavo volumes, whenever i should have gained my first prize at college; but i unluckily failed to qualify myself for the gift; and my copy of the "extracts" i had to purchase for myself ten years after, at a book-stall, when working in the neighbourhood of edinburgh as a journeyman mason. it is not every day one meets with so genuine a highlander as my cousin the merchant; and though he failed to inspire me with all his own ossianic faith and zeal, there were some of the little old celtic practices which he resuscitated _pro tempore_ in his father's household, that i learned to like very much. he restored the genuine highland breakfasts; and, after hours spent in busy exploration outside, i found i could as thoroughly admire the groaning table, with its cheese, and its trout, and its cold meat, as even the immortal lexicographer himself. some of the dishes, too, which he revived, were at least curious. there was a supply of _gradden_-meal prepared--_i.e._, grain dried in a pot over the fire, and then coarsely ground in a handmill--which made cakes that, when they had hunger for their sauce, could be eaten; and on more than one occasion i shared in a not unpalatable sort of blood-pudding, enriched with butter, and well seasoned with pepper and salt, the main ingredient of which was derived, through a judicious use of the lancet, from the _yeld_ cattle of the farm. the practice was an ancient, and by no means unphilosophic one. in summer and early autumn there is plenty of grass in the highlands; but, of old at least, there used to be very little grain in it before the beginning of october; and as the cattle could, in consequence, provide themselves with a competent supply of blood from the grass, when their masters, who could not eat grass, and had little else that they could eat, were able to acquire very little, it was opportunely discovered that, by making a division in this way of the all-essential fluid, accumulated as a common stock, the circumstances of the cattle and their owners could be in some degree equalized. with these peculiarly highland dishes there mingled others not less genuine--now and then a salmon from the river, and a haunch of venison from the hill-side--which i relished better still; and if all highlanders live but as well in the present day as i did during my stay with my aunt and cousins, they would be rather unreasonable were they greatly to complain. there were some of the other highland restorations effected by my cousin that pleased me much. he occasionally gathered at night around the central ha' fire a circle of the elderly men of the neighbourhood, to repeat long-derived narratives of the old clan feuds of the district, and wild fingalian legends; and though, of course, ignorant of the language in which the stories were conveyed, by taking my seat beside cousin george, and getting him to translate for me in an under tone, as the narratives went on, i contrived to carry away with me at least as much of the clan stories and legends as i ever after found use for. the clan stories were waxing at the time rather dim and uncertain in sutherland. the county, through the influence of its good earls and its godly lords reay, had been early converted to protestantism; and its people had in consequence ceased to take liberties with the throats and cattle of their neighbours, about a hundred years earlier than in any other part of the scotch highlands. and as for the fingalian legends, they were, i found, very wild legends indeed. some of them immortalized wonderful hunters, who had excited the love of fingal's lady, and whom her angry and jealous husband had sent out to hunt monstrous wild boars with poisonous bristles on their backs,--secure in this way of getting rid of them. and some of them embalmed the misdeeds of spiritless diminutive fions, not very much above fifteen feet in height, who, unlike their more active companions, could not leap across the cromarty or dornoch firths on their spears, and who, as was natural, were very much despised by the women of the tribe. the pieces of fine sentiment and brilliant description discovered by macpherson seemed never to have found their way into this northern district. but, told in fluent gaelic, in the great "ha'," the wild legends served every necessary purpose equally well. the "ha'" in the autumn nights, as the days shortened and the frosts set in, was a genial place; and so attached was my cousin to its distinctive principle--the fire in the midst--as handed down from the "days of other years," that in the plan of a new two-storied house for his father, which he had procured from a london architect, one of the nether rooms was actually designed in the circular form; and a hearth like a millstone, placed in the centre, represented the place of the fire. but there was, as i remarked to cousin george, no corresponding central hole in the room above, through which to let up the smoke; and i questioned whether a nicely plastered apartment, round as a band-box, with the fire in the middle, like the sun in the centre of an orrery, would have been quite like anything ever seen in the highlands before. the plan, however, was not destined to encounter criticism, or give trouble in the execution of it. on sabbaths my cousin and his two brothers attended the parish church, attired in the full highland dress; and three handsome, well-formed men they were; but my aunt, though mayhap not quite without the mother's pride, did not greatly relish the exhibition; and oftener than once i heard her say so to her sister my mother; though she, smitten by the gallant appearance of her nephews, seemed inclined rather to take the opposite side. my uncle, on the other hand, said nothing either for or against the display. he had been a keen highlander in his younger days; and when the inhibition against wearing tartan and the philabeg had been virtually removed, in consideration of the achievements of the "hardy and dauntless men" who, according to chatham, conquered for england "in every quarter of the globe," he had celebrated the event in a merrymaking, at which the dance was kept up from night till morning; but though he retained, i suspect, his old partialities, he was now a sobered man; and when i ventured to ask him, on one occasion, why he too did not get a sunday kilt, which, by the way, he would "_have set_," notwithstanding his years, as well as any of his sons, he merely replied with a quiet "no, no; there's no fool like an old fool." chapter vi. "when they sawe the darksome night, they sat them downe and cryed."--babes in the wood. i spent the holidays of two other autumns in this delightful highland valley. on the second, as on the first occasion, i had accompanied my mother, specially invited; but the third journey was an unsanctioned undertaking of my own and a cromarty cousin, my contemporary, to whom, as he had never travelled the way, i had to act as protector and guide. i reached my aunt's cottage without mishap or adventure of any kind; but found, that during the twelvemonth which had just elapsed, great changes had taken place in the circumstances of the household. my cousin george, who had married in the interim, had gone to reside in a cottage of his own; and i soon ascertained that my cousin william, who had been for several months resident with his father, had not nearly so many visitors as before; nor did presents of salmon and haunches of venison come at all so often the way. immediately after the final discomfiture of napoleon, an extensive course of speculation in which he had ventured to engage had turned out so ill, that, instead of making him a fortune, as at first seemed probable, it had landed him in the _gazette_; and he was now tiding over the difficulties of a time of settlement, six hundred miles from the scene of disaster, in the hope of being soon enabled to begin the world anew. he bore his losses with quiet magnanimity; and i learned to know and like him better during his period of eclipse than in the previous time, when summer friends had fluttered around him by scores. he was a generous, warm-hearted man, who felt, with the force of an implanted instinct not vouchsafed to all, that it is more blessed to give than to receive; and it was doubtless a wise provision of nature, and worthy, in this point of view, the special attention of moralists and philosophers, that his old associates, the grand gentlemen, did not now often come his way; seeing that his inability any longer to give would cost him, in the circumstances, great pain. i was much with my cousin george in his new dwelling. it was one of the most delightful of highland cottages, and george was happy in it, far above the average lot of humanity, with his young wife. he had dared, in opposition to the general voice of the district, to build it half-way up the slope of a beautiful tomhan, that, waving with birch from base to summit, rose regular as a pyramid from the bottom of the valley, and commanded a wide view of loch shin on the one hand, with the moors and mountains that lie beyond; and overlooked, on the other, with all the richer portions of the barony of gruids, the church and picturesque hamlet of lairg. half-hidden by the graceful birchen trees that sprang up thick around, with their silvery boles and light foliage, it was rather a nest than a house; and george, emancipated, by his reading, and his residence for a time in the south, from at least the wilder beliefs of the locality, failed to suffer, as had been predicted, for his temerity; as the "good people," who, much to their credit, had made choice of the place for themselves long before, never, to his knowledge, paid him a visit. he had brought his share of the family library with him; and it was a large share. he had mathematical instruments too, and a colour-box, and the tools of his profession; in especial, large hammers fitted to break great stones; and i was generously made free of them all,--books, instruments, colour-box, and hammers. his cottage, too, commanded, from its situation, a delightful variety of most interesting objects. it had all the advantages of my uncle's domicile, and a great many more. the nearer shores of loch shin were scarce half a mile away; and there was a low long promontory which shot out into the lake, that was covered at that time by an ancient wood of doddered time-worn trees, and bore amid its outer solitudes, where the waters circled round its terminal apex, one of those towers of hoary eld--memorials, mayhap, of the primeval stone-period in our island, to which the circular erections of glenelg and dornadilla belong. it was formed of undressed stones of vast size, uncemented by mortar; and through the thick walls ran winding passages--the only covered portions of the building, for the inner area had never been furnished with a roof--in which, when a sudden shower descended, the loiterer amid the ruins could find shelter. it was a fascinating place to a curious boy. some of the old trees had become mere whitened skeletons, that stretched forth their blasted arms to the sky, and had so slight a hold of the soil, that i have overthrown them with a delightful crash, by merely running against them; the heath rose thick beneath, and it was a source of fearful joy to know that it harboured snakes full three feet long; and though the loch itself is by no means one of our finer highland lochs, it furnished, to at least my eye at this time, a delightful prospect in still october mornings, when the light gossamer went sailing about in white filmy threads, and birch and hazel, glorified by decay, served to embroider with gold the brown hillsides which, standing up on either hand in their long vista of more than twenty miles, form the barriers of the lake; and when the sun, still struggling with a blue diluted haze, fell delicately on the smooth surface, or twinkled for a moment on the silvery coats of the little trout, as they sprang a few inches into the air, and then broke the water into a series of concentric rings in their descent. when i last passed the way, both the old wood and the old tower were gone; and for the latter, which, though much a ruin, might have survived for ages, i found only a long extent of dry-stone dike, and the wide ring formed by the old foundation-stones, which had proved too massive to be removed. a greatly more entire erection of the same age and style, known of old as dunaliscag--which stood on the ross-shire side of the dornoch firth, and within whose walls, forming, as it did, a sort of half-way stage, i used, on these sutherlandshire journeys, to eat my piece of cake with a double relish--i found, on last passing the way, similarly represented. its grey venerable walls, and dark winding passages of many steps--even the huge pear-shaped lintel, which had stretched over its little door, and which, according to tradition, a great fingalian lady had once thrown across the dornoch firth from off the point of her spindle--had all disappeared, and i saw instead, only a dry-stone wall. the men of the present generation do certainly live in a most enlightened age--an age in which every trace of the barbarism of our early ancestors is fast disappearing; and were we but more zealous in immortalizing the public benefactors who efface such dark memorials of the past as the tower of dunaliscag and the promontory of loch shin, it would be, doubtless, an encouragement to others to speed us yet further on in the march of improvement. it seems scarce fair that the enlightened destroyers of arthur's oven or of the bas-relief known as robin of redesdale, or of the town-cross of edinburgh, should enjoy all the celebrity attendant on such acts, while the equally deserving iconoclasts of dunaliscag and the tower of loch shin should be suffered to die without their fame. i remember spending one singularly delightful morning with cousin george beside the ancient tower. he pointed out to me, amid the heath, several plants to which the old highlanders used to attach occult virtues,--plants that disenchanted bewitched cattle, not by their administration as medicines to the sick animals, but by bringing them in contact, as charms, with the injured milk; and plants which were used as philters, either for procuring love, or exciting hatred. it was, he showed me, the root of a species of orchis that was employed in making the philters. while most of the radical fibres of the plant retain the ordinary cylindrical form, two of their number are usually found developed into starchy tubercles; but, belonging apparently to different seasons, one of the two is of a dark colour, and of such gravity that it sinks in water; while the other is light-coloured, and floats. and a powder made of the light-coloured tubercle formed the main ingredient, said my cousin, in the love philter; while a powder made of the dark-coloured one excited, it was held, only antipathy and dislike. and then george would speculate on the origin of a belief which could, as he said, neither be suggested by reason, nor tested by experience. living, however, among a people with whom beliefs of the kind were still vital and influential, he did not wholly escape their influence; and i saw him, in one instance, administer to an ailing cow a little live trout, simply because the traditions of the district assured him, that a trout swallowed alive by the creature was the only specific in the case. some of his highland stories were very curious. he communicated to me, for example, beside the broken tower, a tradition illustrative of the celtic theory of dreaming, of which i have since often thought. two young men had been spending the early portion of a warm summer day in exactly such a scene as that in which he communicated the anecdote. there was an ancient ruin beside them, separated, however, from the mossy bank on which they sat, by a slender runnel, across which there lay, immediately over a miniature cascade, a few withered grass stalks. overcome by the heat of the day, one of the young men fell asleep; his companion watched drowsily beside him; when all at once the watcher was aroused to attention by seeing a little indistinct form, scarce larger than a humble-bee, issue from the mouth of the sleeping man, and, leaping upon the moss, move downwards to the runnel, which it crossed along the withered grass stalks, and then disappeared amid the interstices of the ruin. alarmed by what he saw, the watcher hastily shook his companion by the shoulder, and awoke him; though, with all his haste, the little cloud-like creature, still more rapid in its movements, issued from the interstice into which it had gone, and, flying across the runnel, instead of creeping along the grass stalks and over the sward, as before, it re-entered the mouth of the sleeper, just as he was in the act of awakening. "what is the matter with you?" said the watcher, greatly alarmed. "what ails you?" "nothing ails me," replied the other; "but you have robbed me of a most delightful dream. i dreamed i was walking through a fine rich country, and came at length to the shores of a noble river; and, just where the clear water went thundering down a precipice, there was a bridge all of silver, which i crossed; and then, entering a noble palace on the opposite side, i saw great heaps of gold and jewels, and i was just going to load myself with treasure, when you rudely awoke me, and i lost all." i know not what the asserters of the clairvoyant faculty may think of the story; but i rather believe i have occasionally seen them make use of anecdotes that did not rest on evidence a great deal more solid than the highland legend, and that illustrated not much more clearly the philosophy of the phenomena with which they profess to deal. of all my cousins, cousin george was the one whose pursuits most nearly resembled my own, and in whose society i most delighted to share. he did sometimes borrow a day from his work, even after his marriage; but then, according to the poet, it was "the love he bore to science was in fault." the borrowed day was always spent in transferring to paper some architectural design, or in working out some mathematical problem, or in rendering some piece of gaelic verse into english, or some piece of english prose into gaelic; and as he was a steady, careful man, the appropriated day was never seriously missed. the winter, too, was all his own, for, in those northern districts, masons are never employed from a little after hallowday, till the second, or even third month of spring, a circumstance which i carefully noted at this time in its bearing on the amusements of my cousin, and which afterwards weighed not a little with me when i came to make choice of a profession for myself. and george's winters were always ingeniously spent. he had a great command of gaelic, and a very tolerable command of english; and so a translation of bunyan's "visions of heaven and hell," which he published several years subsequent to this period, was not only well received by his country folk of sutherland and ross, but was said by competent judges to be really a not inadequate rendering of the meaning and spirit of the noble old tinker of elstow. i, of course, could be no authority respecting the merits of a translation, the language of which i did not understand; but living much amid the literature of a time when almost every volume, whether the virgil of a dryden, or the meditations of a hervey, was heralded by its sets of complimentary verses, and having a deep interest in whatever cousin george undertook and performed, i addressed to him, in the old style, a few introductory stanzas, which, to indulge me in the inexpressible luxury of seeing myself in print for the first time, he benevolently threw into type. they survive to remind me that my cousin's belief in ossian did exert some little influence over my phraseology when i addressed myself to him, and that, with the rashness natural to immature youth, i had at this time the temerity to term myself "poet." yes, oft i've said, as oft i've seen the men who dwell its hills among, that morven's land has ever been a land of valour, worth, and song. but ignorance, of darkness dire, has o'er that land a mantle spread; and all untuned and rude the lyre that sounds beneath its gloomy shade. with muse of calm untiring wing, oh, be it thine, my friend, to show the celtic swain how saxons sing of hell's dire gloom and heaven's glow so shall the meed of fame be thine, the glistening bay-wreath green and gay; thy poet, too, though weak his line, shall frame for thee th' approving lay. longing for some profession in which his proper work would give exercise to the faculties which he most delighted to cultivate, my cousin resolved on becoming candidate for a gaelic society school--a poor enough sort of office then, as now; but which, by investing a little money in cattle, by tilling a little croft, and by now and then emitting from the press a gaelic translation, might, he thought, be rendered sufficiently remunerative to supply the very moderate wants of himself and his little family. and so he set out for edinburgh, amply furnished with testimonials that meant more in his case than testimonials usually mean, to stand an examination before a committee of the gaelic school society. unluckily for his success, however, instead of bringing with him his ordinary sabbath-day suit of dark brown and blue (the kilt had been assumed for but a few weeks, to please his brother william), he had provided himself with a suit of tartan, as at once cheap and respectable, and appeared before the committee--if not in the garb, in at least the many-coloured hues, of his clan--a robust manly highlander, apparently as well suited to enact the part of colour-serjeant to the forty-second, as to teach children their letters. a grave member of the society, at that time in high repute for sanctity of character, but who afterwards, becoming righteous overmuch, was loosened from his charge, and straightway, spurning the ground, rose into an irvingite angel, came at once to the conclusion that no such type of man, encased in clan-tartan, could possibly have the root of the matter in him; and so he determined that cousin george should be cast in the examination. but then, as it could not be alleged with any decency that my cousin was inadmissible on the score of his having too much tartan, it was agreed that he should be declared inadmissible on the score of his having too little gaelic. and, of course, at this result the examinators arrived; and george, ultimately to his advantage, was cast accordingly. i still remember the astonishment evinced by a worthy catechist of the north--himself a gaelic teacher--on being told how my cousin had fared. "george munro not allowed to pass," he said, "for want of right gaelic! why, he has more right gaelic in his own self than all the society's teachers in this corner of scotland put together. they are the _curiousest_ people, some of these good gentlemen of the edinburgh committees, that i ever heard of: they're just like our country lawyers." it would, however, be far from fair to regard this transaction, which took place, i may mention, so late as the year , as a specimen of the actings of either civic societies or country lawyers. george's chief examinator on the occasion was the minister of the gaelic chapel of the place, at that time one of the society's committee for the year; and, not being a remarkably scrupulous man, he seems to have stretched a point or two, in compliance with the pious wishes and occult judgment of the society's secretary. but the anecdote is not without its lesson. when devout walter taits set themselves ingeniously to manoeuvre with the purest of intentions, and for what they deem the best of purposes--when, founding their real grounds of objection on one set of appearances, they found their ostensible grounds of objection on another and entirely different set--they are always exposed to the signal danger of--getting indevout duncan m'caigs to assist them. only two years from the period of my cousin's examination before the society, his reverend examinator received at the bar of the high court of justiciary, in the character of a thief convicted of eleven several acts of stealing, sentence of transportation for fourteen years. i had several interesting excursions with my cousin william. we found ourselves one evening--on our way home from a mineral spring which he had discovered among the hills--in a little lonely valley, which opened transversely into that of the gruids, and which, though its sides were mottled with green furrow-marked patches, had not at the time a single human habitation. at the upper end, however, there stood the ruins of a narrow two-storied house, with one of its gables still entire from foundation-stone to the shattered chimney-top, but with the other gable, and the larger part of the front wall, laid prostrate along the sward. my cousin, after bidding me remark the completeness of the solitude, and that the eye could not command from the site of the ruin a single spot where man had ever dwelt, told me that it had been the scene of the strict seclusion, amounting almost to imprisonment, about eighty years before, of a lady of high birth, over whom, in early youth, there had settled a sad cloud of infamy. she had borne a child to one of the menials of her father's house, which, with the assistance of her paramour, she had murdered; and being too high for the law to reach in these northern parts, at a time when the hereditary jurisdiction still existed entire, and her father was the sole magistrate, possessed of the power of life and death in the district, she was sent by her family to wear out life in this lonely retreat, in which she remained secluded from the world for more than half a century. and then, long after the abolition of the local jurisdictions, and when her father and brother, with the entire generation that knew of her crime, had passed away, she was permitted to take up her abode in one of the seaport towns of the north, where she was still remembered at this time as a crazy old lady, invariably silent and sullen, that used to be seen in the twilight flitting about the more retired lanes and closes, like an unhappy ghost. the story, as told me in that solitary valley, just as the sun was sinking over the hill beyond, powerfully impressed my fancy. crabbe would have delighted to tell it; and i now relate it, as it lies fast wedged in my memory, mainly for the peculiar light which it casts on the times of the hereditary jurisdictions. it forms an example of one of the judicial banishments of an age that used, in ordinary cases, to save itself all sorts of trouble of the kind, by hanging its victims. i may add, that i saw a good deal of the neighbourhood at this time in the company of my cousin, and gleaned, from my visits to shieling and cottage, most of my conceptions of the state of the northern highlands, ere the clearance system had depopulated the interior of the country, and precipitated its poverty-stricken population upon the coasts. there was, however, one of my excursions with cousin william, that turned out rather unfortunately. the river shin has its bold salmon-leap, which even yet, after several hundred pounds' worth of gunpowder have been expended in sloping its angle of ascent, to facilitate the passage of the fish, is a fine picturesque object, but which at this time, when it presented all its original abruptness, was a finer object still. though distant about three miles from my uncle's cottage, we could distinctly hear its roarings from beside his door, when october nights were frosty and still; and as we had been told many strange stories regarding it--stories about bold fishers who had threaded their dangerous way between the overhanging rock and the water, and who, striking outwards, had speared salmon through the foam of the cataract as they leaped--stories, too, of skilful sportsmen, who, taking their stand in the thick wood beyond, had shot the rising animals, as one shoots a bird flying,--both my cromarty cousin and myself were extremely desirous to visit the scene of such feats and marvels; and cousin william obligingly agreed to act as our guide and instructor by the way. he did look somewhat askance at our naked feet; and we heard him remark, in an under tone, to his mother, that when he and his brothers were boys, she never suffered _them_ to visit her cromarty relations unshod; but neither cousin walter nor myself had the magnanimity to say, that _our_ mothers had also taken care to see us shod; but that, deeming it lighter and cooler to walk barefoot, the good women had no sooner turned their backs than we both agreed to fling our shoes into a corner, and set out on our journey without them. the walk to the salmon-leap was a thoroughly delightful one. we passed through the woods of achanie, famous for their nuts; startled, as we went, a herd of roe deer; and found the leap itself far exceeded all anticipation. the shin becomes savagely wild in its lower reaches. rugged precipices of gneiss, with scattered bushes fast anchored in the crevices, overhang the stream, which boils in many a dark pool, and foams over many a steep rapid; and immediately beneath, where it threw itself headlong, at this time, over the leap--for it now merely rushes in snow adown a steep slope--there was a caldron, so awfully dark and profound, that, according to the accounts of the district, it had no bottom; and so vexed was it by a frightful whirlpool, that no one ever fairly caught in its eddies had succeeded, it was said, in regaining the shore. we saw, as we stood amid the scraggy trees of an overhanging wood, the salmon leaping up by scores, most of them, however, to fall back again into the pool--for only a very few stray fish that attempted the cataract at its edges seemed to succeed in forcing their upward way; we saw, too, on a shelf of the precipitous but wooded bank, the rude hut, formed of undressed logs, where a solitary watcher used to take his stand, to protect them from the spear and fowlingpiece of the poacher, and which in stormy nights, when the cry of the kelpie mingled with the roar of the flood, must have been a sublime lodge in the wilderness, in which a poet might have delighted to dwell. i was excited by the scene; and, when heedlessly leaping from a tall lichened stone into the long heath below, my right foot came so heavily in contact with a sharp-edged fragment of rock concealed in the moss, that i almost screamed aloud with pain. i, however, suppressed the shriek, and, sitting down and setting my teeth close, bore the pang, until it gradually moderated, and my foot, to the ankle, seemed as if almost divested of feeling. in our return, i halted as i walked, and lagged considerably behind my companions; and during the whole evening the injured foot seemed as if dead, save that it glowed with an intense heat. i was, however, at ease enough to write a sublime piece of blank verse on the cataract; and, proud of my production, i attempted reading it to cousin william. but william had taken lessons in recitation under the great mr. thelwall, politician and elocutionist; and deeming it proper to set me right in all the words which i mispronounced--three out of every four at least, and not unfrequently the fourth word also--the reading of the piece proved greatly stiffer and slower work than the writing of it; and, somewhat to my mortification, my cousin declined giving me any definite judgment on its merits, even when i had done. he insisted, however, on the signal advantages of reading well. he had an acquaintance, he said, a poet, who had taken lessons under mr. thelwall, and who, though his verses, when he published, met with no great success, was so indebted to his admirable elocution, as to be invariably successful when he read them to his friends. next morning my injured foot was stiff and sore; and, after a few days of suffering, it suppurated and discharged great quantities of blood and matter. it was, however, fast getting well again, when, tired of inaction, and stirred up by my cousin walter, who wearied sadly of the highlands, i set out with him, contrary to all advice, on my homeward journey, and, for the first six or eight miles, got on tolerably well. my cousin, a stout, active lad, carried the bag of highland luxuries--cheese, and butter, and a full peck of nuts--with which we had been laden by my aunt; and, by way of indemnity for taking both my share of the burden and his own, he demanded of me one of my long extempore stories, which, shortly after leaving my aunt's cottage, i accordingly began. my stories, when i had cousin walter for my companion, were usually co-extensive with the journey to be performed: they became ten, fifteen, or twenty miles long, agreeably to the measure of the road, and the determination of the mile-stones; and what was at present required was a story of about thirty miles in length, whose one end would touch the barony of gruids, and the other the cromarty ferry. at the end, however, of the first six or eight miles, my story broke suddenly down, and my foot, after becoming very painful, began to bleed. the day, too, had grown raw and unpleasant, and after twelve o'clock there came on a thick wetting drizzle. i limped on silently in the rear, leaving at every few paces a blotch of blood upon the road, until, in the parish of edderton, we both remembered that there was a short cut through the hills, which two of our older cousins had taken during the previous year, when on a similar journey; and as walter deemed himself equal to anything which his elder cousins could perform, and as i was exceedingly desirous to get home as soon as possible, and by the shortest way, we both struck up the hill-side, and soon found ourselves in a dreary waste, without trace of human habitation. walter, however, pushed on bravely and in the right direction; and, though my head was now becoming light, and my sight dim, i succeeded in struggling after him, until, just as the night was falling, we reached a heathy ridge, which commands the northern sea-board of the cromarty firth, and saw the cultivated country and the sands of nigg lying only a few miles below. the sands are dangerous at certain hours of the tide, and accidents frequently happen in the fords; but then there could, we thought, be no fear of us; for though walter could not swim, i could; and as i was to lead the way, he of course would be safe, by simply avoiding the places where i lost footing. the night fell rather thick than dark, for there was a moon overhead, though it could not be seen through the cloud; but, though walter steered well, the downward way was exceedingly rough and broken, and we had wandered from the path. i retain a faint but painful recollection of a scraggy moor, and of dark patches of planting, through which i had to grope onwards, stumbling as i went; and then, that i began to feel as if i were merely dreaming, and that the dream was a very horrible one, from which i could not awaken. and finally, on reaching a little cleared spot on the edge of the cultivated country, i dropped down as suddenly as if struck by a bullet, and, after an ineffectual attempt to rise, fell fast asleep. walter was much frightened; but he succeeded in carrying me to a little rick of dried grass which stood up in the middle of the clearing; and after covering me well up with the grass, he laid himself down beside me. anxiety, however, kept him awake; and he was frightened, as he lay, to hear the sounds of psalm-singing, in the old gaelic style, coming apparently from a neighbouring clump of wood. walter believed in the fairies; and, though psalmody was not one of the reputed accomplishments of the "good people" in the low country, he did not know but that in the highlands the case might be different. some considerable time after the singing had ceased, there was a slow, heavy step heard approaching the rick; an exclamation in gaelic followed; and then a rough hard hand grasped walter by the naked heel. he started up, and found himself confronted by an old, grey-headed man, the inmate of a cottage, which, hidden in the neighbouring clump, had escaped his notice. the old man, in the belief that we were gipsies, was at first disposed to be angry at the liberty we had taken with his hayrick; but walter's simple story mollified him at once, and he expressed deep regret that "poor boys, who had met with an accident," should have laid them down in such a night under the open sky, and a house so near. "it was putting disgrace," he said, "on a christian land." i was assisted into his cottage, whose only other inmate, an aged woman, the old highlander's wife, received us with great kindness and sympathy; and on walter's declaring our names and lineage, the hospitable regrets and regards of both host and hostess waxed stronger and louder still. they knew our maternal grandfather and grandmother, and remembered old donald roy; and when my cousin named my father, there was a strongly-expressed burst of sorrow and commiseration, that the son of a man whom they had seen so "well to do in the world" should be in circumstances so deplorably destitute. i was too ill to take much note of what passed. i only remember, that of the food which they placed before me, i could partake of only a few spoonfuls of milk; and that the old woman, as she washed my feet, fell a-crying over me. i was, however, so greatly recruited by a night's rest in their best bed, as to be fit in the morning to be removed, in the old man's _rung_-cart, to the house of a relation in the parish of nigg, from which, after a second day's rest, i was conveyed in another cart to the cromarty ferry. and thus terminated the last of my boyish visits to the highlands. both my grandfather and grandmother had come of long-lived races, and death did not often knock at the family door. but the time when the latter "should cross the river," though she was some six or eight years younger than her husband, came first; and so, according to bunyan, she "called for her children, and told them that her hour had come." she was a quiet, retiring woman, and, though intimately acquainted with her bible, not in the least fitted to make a female professor of theology: she could _live_ her religion better than _talk_ it; but she now earnestly recommended to her family the great interests once more; and, as its various members gathered round her bed, she besought one of her daughters to read to her, in their hearing, that eighth chapter of the romans which declares that "there is now no condemnation to them which are in christ jesus, who walk not after the flesh, but after the spirit." she repeated, in a sinking voice, the concluding verses,--"for i am persuaded, that neither death nor life, nor angels nor principalities nor powers, nor things present nor things to come, nor height nor depth, nor any other creature, shall be able to separate us from the love of god, which is in christ jesus our lord." and, resting in confidence on the hope which the passage so powerfully expresses, she slept her last sleep, in simple trust that all would be well with her in the morning of the general awakening. i retain her wedding-ring, the gift of donald roy. it is a sorely-wasted fragment, worn through on one of the sides, for she had toiled long and hard in her household, and the breach in the circlet, with its general thinness, testify to the fact; but its gold is still bright and pure; and, though not much of a relic-monger, i would hesitate to exchange it for the holy coat of trèves, or for waggon-loads of the wood of the "true cross." my grandmother's term of life had exceeded by several twelvemonths the full threescore and ten; but when, only a few years after, death next visited the circle, it was on its youngest members that his hand was laid. a deadly fever swept over the place, and my two sisters--the one in her tenth, the other in her twelfth year--sank under it within a few days of each other. jean, the elder, who resided with my uncles, was a pretty little girl, of fine intellect, and a great reader; catherine, the younger, was lively and affectionate, and a general favourite; and their loss plunged the family in deep gloom. my uncles made little show of grief, but they felt strongly: my mother for weeks and months wept for her children, like rachel of old, and refused to be comforted, because they were not; but my grandfather, now in his eighty-fifth year, seemed to be rendered wholly bankrupt in heart by their loss. as is perhaps not uncommon in such cases, his warmer affections strode across the generation of grown-up men and women--his sons and daughters--and luxuriated among the children their descendants. the boys, his grandsons, were too wild for him; but the two little girls--gentle and affectionate--had seized on his whole heart; and now that they were gone, it seemed as if he had nothing in the world left to care for. he had been, up till this time, notwithstanding his great age, a hale and active man. in , when france threatened invasion, he was, though on the verge of seventy, one of the first men in the place to apply for arms as a volunteer; but now he drooped and gradually sunk, and longed for the rest of the grave. "it is god's will," i heard him say about this time, to a neighbour who congratulated him on his long term of life and unbroken health--"it is god's will, but not my desire." and in rather more than a twelvemonth after the death of my sisters, he was seized by almost his only illness--for, for nearly seventy years he had not been confined to bed for a single day--and was carried off in less than a week. during the last few days, the fever under which he sank mounted to his brain; and he talked in unbroken narrative of the events of his past life. he began with his earliest recollections; described the battle of culloden as he had witnessed it from the hill of cromarty, and the appearance of duke william and the royal army as seen during a subsequent visit to inverness; ran over the after events of his career--his marriage, his interviews with donald roy, his business transactions with neighbouring proprietors, long dead at the time; and finally, after reaching, in his oral history, his term of middle life, he struck off into another track, and began laying down, with singular coherency, the statements of doctrine in a theological work of the old school, which he had been recently perusing. and finally, his mind clearing as his end approached, he died in good hope. it is not uninteresting to look back on two such generations of scotchmen as those to which my uncles and grandfather belonged. they differed very considerably in some respects. my grandfather, with most of his contemporaries of the same class, had a good deal of the tory in his composition. he stood by george iii. in the early policy of his reign, and by his adviser lord bute; reprobated wilkes and junius; and gravely questioned whether washington and his coadjutors, the american republicans, were other than bold rebels. my uncles, on the contrary, were stanch whigs, who looked upon washington as perhaps the best and greatest man of modern times--stood firm by the policy of fox, as opposed to that of pitt--and held that the war with france, which immediately succeeded the first revolution, was, however thoroughly it changed its character afterwards, one of unjustifiable aggression. but however greatly my uncles and grandfather may have differed on these points, they were equally honest men. the rising generation can perhaps form no very adequate conception of the number and singular interest of the links which serve to connect the recollections of a man who has seen his fiftieth birth-day, with what to them must appear a remote past. i have seen at least two men who fought at culloden--one on the side of the king, the other on that of the prince--and, with these, not a few who witnessed the battle from a distance. i have conversed with an aged woman that had conversed, in turn, with an aged man who had attained to mature manhood when the persecutions of charles and james were at their height, and remembered the general regret excited by the death of renwick. my eldest maternal aunt--the mother of cousin george--remembered old john feddes--turned of ninety at the time; and john's buccaneering expedition could not have dated later than the year . i have known many who remembered the abolition of the hereditary jurisdictions; and have listened to stories of executions which took place on the gallows-hills of burghs and sheriffdoms, and of witch-burnings perpetrated on town links and baronial laws. and i have felt a strange interest in these glimpses of a past so unlike the present, when thus presented to the mind as personal reminiscences, or as well-attested traditions, removed from the original witnesses by but a single stage. all, for instance, which i have yet read of witch-burnings has failed to impress me so strongly as the recollections of an old lady who in was carried in her nurse's arms--for she was almost an infant at the time--to witness a witch-execution in the neighbourhood of dornoch--the last which took place in scotland. the lady well remembered the awe-struck yet excited crowd, the lighting of the fire, and the miserable appearance of the poor fatuous creature whom it was kindled to consume, and who seemed to be so little aware of her situation, that she held out her thin shrivelled hands to warm them at the blaze. but what most impressed the narrator--for it must have been a frightful incident in a sad spectacle--was the circumstance that, when the charred remains of the victim were sputtering and boiling amid the intense heat of the flames, a cross gust of wind suddenly blew the smoke athwart the spectators, and she felt in her attendant's arms as if in danger of being suffocated by the horrible stench. i have heard described, too, by a man whose father had witnessed the scene, an execution which took place, after a brief and inadequate trial, on the burgh-gallows of tain. the supposed culprit, a strathcarron highlander, had been found lurking about the place, noting, as was supposed, where the burghers kept their cattle, and was hung as a spy; but they all, after the execution, came to deem him innocent, from the circumstance that, when his dead body was dangling in the wind, a white pigeon had come flying the way, and, as it passed over, half-encircled the gibbet. one of the two culloden soldiers whom i remember was an old forester who lived in a picturesque cottage among the woods of the cromarty hill; and in his last illness, my uncles, whom i had always leave to accompany, used not unfrequently to visit him. he had lived at the time his full century, and a few months more: and i still vividly remember the large gaunt face that used to stare from the bed as they entered, and the huge, horny hand. he had been settled in life, previous to the year , as the head gardener of a northern proprietor, and little dreamed of being engaged in war; but the rebellion broke out; and as his master, a stanch whig, had volunteered to serve on behalf of his principles in the royal army, his gardener, a "mighty man of his hands," went with him. as his memory for the later events of his life was gone at this time, its preceding forty years seemed a blank, from which not a single recollection could be drawn; but well did he remember the battle, and more vividly still, the succeeding atrocities of the troops of cumberland. he had accompanied the army, after its victory at culloden, to the camp at fort-augustus, and there witnessed scenes of cruelty and spoliation of which the recollection, after the lapse of seventy years, and in his extreme old age, had still power enough to set his scotch blood aboil. while scores of cottages were flaming in the distance, and blood not unfrequently hissing on the embers, the men and women of the army used to be engaged in racing in sacks, or upon highland ponies; and when the ponies were in request, the women, who must have sat for their portraits in hogarth's "march to finchley," took their seats astride like the men. gold circulated and liquor flowed in abundance; and in a few weeks there were about twenty thousand head of cattle brought in by marauding parties of the soldiery from the crushed and impoverished highlanders; and groups of drovers from yorkshire and the south of scotland--coarse vulgar men--used to come every day to share in the spoil, by making purchases at greatly less than half-price. my grandfather's recollections of culloden were merely those of an observant boy of fourteen, who had witnessed the battle from a distance. the day, he has told me, was drizzly and thick; and on reaching the brow of the hill of cromarty, where he found many of his townsfolk already assembled, he could scarce see the opposite land. but the fog gradually cleared away; first one hill-top came into view, and then another; till at length the long range of coast, from the opening of the great caledonian valley to the promontory of burgh-head, was dimly visible through the haze. a little after noon there suddenly rose a round white cloud from the moor of culloden, and then a second round white cloud beside it. and then the two clouds mingled together, and went rolling slantways on the wind towards the west; and he could hear the rattle of the smaller fire-arms mingling with the roar of the artillery. and then, in what seemed an exceedingly brief space of time, the cloud dissipated and disappeared, the boom of the greater guns ceased, and a sharp intermittent patter of musketry passed on towards inverness. but the battle was presented to the imagination, in these old personal narratives, in many a diverse form. i have been told by an ancient woman, who, on the day of the fight, was engaged in tending some sheep on a solitary common near munlochy, separated from the moor of culloden by the firth, and screened by a lofty hill, that she sat listening in terror to the boom of the cannon; but that she was still more scared by the continuous howling of her dog, who sat upright on his haunches all the time the firing lasted, with his neck stretched out towards the battle, and "looking as if he saw a spirit." such are some of the recollections which link the memories of a man who has lived his half-century, to those of the preceding age, and which serve to remind him how one generation of men after another break and disappear on the shores of the eternal world, as wave after wave breaks in foam upon the beach, when storms are rising, and the ground-swell sets in heavily from the sea. chapter vii. "whose elfin prowess scaled the orchard wall."--rogers. some of the wealthier tradesmen of the town, dissatisfied with the small progress which their boys were making under the parish schoolmaster, clubbed together and got a schoolmaster of their own; but, though a rather clever young man, he proved an unsteady one, and, regular in his irregularities, got diurnally drunk, on receiving the instalments of his salary at term-days, as long as his money lasted. getting rid of him, they procured another--a licentiate of the church--who for some time promised well. he seemed steady and thoughtful, and withal a painstaking teacher; but coming in contact with some zealous baptists, they succeeded in conjuring up such a cloud of doubt around him regarding the propriety of infant baptism, that both his bodily and mental health became affected by his perplexities, and he had to resign his charge. and then, after a pause, during which the boys enjoyed a delightfully long vacation, they got yet a third schoolmaster, also a licentiate, and a person of a high, if not very consistent religious profession, who was always getting into pecuniary difficulties, and always courting, though with but little success, wealthy ladies, who, according to the poet, had "acres of charms." to the subscription school i was transferred, at the instance of uncle james, who remained quite sure, notwithstanding the experience of the past, that i was destined to be a scholar. and, invariably fortunate in my opportunities of amusement, the transference took place only a few weeks ere the better schoolmaster, losing health and heart in a labyrinth of perplexity resigned his charge. i had little more than time enough to look about me on the new forms, and to renew, on a firmer foundation than ever, my friendship with my old associate of the cave--who had been for the two previous years an inmate of the subscription school, and was now less under maternal control than before--when on came the long vacation; and for four happy months i had nothing to do. my amusements had undergone very little change: i was even fonder of the shores and woods than ever, and better acquainted with the rocks and caves. a very considerable change, however, had taken place in the amusements of the school-fellows my contemporaries, who were now from two to three years older than when i had been associated with them in the parish school. hy-spy had lost its charms; nor was there much of its old interest for them in french and english; whereas my rock excursions they came to regard as very interesting indeed. with the exception of my friend of the cave, they cared little about rocks or stones; but they all liked brambles, and sloes, and _craws-apples_, tolerably well, and took great delight in assisting me to kindle fires in the caverns of the old-coast line, at which we used to broil shell-fish and crabs, taken among the crags and boulders of the ebb below, and roast potatoes, transferred from the fields of the hill above. there was one cave, an especial favourite with us, in which our fires used to blaze day after day for weeks together. it is deeply hollowed in the base of a steep ivy-mantled precipice of granitic gneiss, a full hundred feet in height; and bears on its smoothed sides and roof, and along its uneven bottom,--fretted into pot-like cavities, with large rounded pebbles in them,--unequivocal evidence that the excavating agent to which it owed its existence had been the wild surf of this exposed shore. but for more than two thousand years wave had never reached it: the last general elevation of the land had raised it beyond the reach of the highest stream-tides; and when my gang and i took possession of its twilight recesses, its stony sides were crusted with mosses and liverworts; and a crop of pale, attenuated, sickly-looking weeds, on which the sun had never looked in his strength, sprang thickly up over its floor. in the remote past it had been used as a sort of garner and thrashing-place by a farmer of the parish, named marcus, who had succeeded in rearing crops of bere and oats on two sloping plots at the foot of the cliffs in its immediate neighbourhood; and it was known, from this circumstance, to my uncles and the older inhabitants of the town, as marcus's cave. my companions, however, had been chiefly drawn to it by a much more recent association. a poor highland pensioner--a sorely dilapidated relic of the french-american war, who had fought under general wolfe in his day--had taken a great fancy to the cave, and would fain have made it his home. he was ill at ease in his family;--his wife was a termagant, and his daughter disreputable; and, desirous to quit their society altogether, and live as a hermit among the rocks, he had made application to the gentleman who tenanted the farm above, to be permitted to fit up the cave for himself as a dwelling. so bad was his english, however, that the gentleman failed to understand him; and his request was, as he believed, rejected, while it was in reality only not understood. among the younger folk the cave came to be known, from the incident, as "rory shingles' cave;" and my companions were delighted to believe that they were living in it as rory would have lived, had his petition been granted. in the wild half-savage life which we led, we did contrive to provide for ourselves remarkably well. the rocky shores supplied us with limpets, periwinkles, and crabs, and now and then a lump-fish; the rugged slopes under the precipices, with hips, sloes, and brambles; the broken fragments of wreck along the beach, and the wood above, furnished abundance of fuel; and as there were fields not half a mile away, i fear the more solid part of our diet consisted often of potatoes which we had not planted, and of pease and beans which we had not sown. one of our number contrived to bring away a pot unobserved from his home; another succeeded in providing us with a pitcher; there was a good spring not two hundred yards from the cave mouth, which supplied us with water; and, thus possessed of not merely all that nature requires, but a good deal more, we contrived to fare sumptuously every day. it has been often remarked, that civilized man, when placed in circumstances at all favourable, soon learns to assume the savage. i shall not say that my companions or myself had been particularly civilized in our previous state; but nothing could be more certain, than that during our long vacation, we became very happy, and tolerably perfect savages. the class which we attended was of a kind not opened in any of our accredited schools, and it might be difficult to procure testimonials in its behalf, easily procurable as these usually are; and yet there were some of its lessons which might be conned with some little advantage, by one desirous of cultivating the noble sentiment of self-reliance, or the all-important habit of self-help. at the time, however, they appeared quite pointless enough; and the moral, as in the case of the continental apologue of reynard the fox, seemed always omitted. our parties in these excursions used at times to swell out to ten or twelve--at times to contract to two or three; but what they gained in quantity they always lost in quality, and became mischievous with the addition of every new member, in greatly more than the arithmetical ratio. when most innocent, they consisted of only a brace of members--a warm-hearted, intelligent boy from the south of scotland, who boarded with two elderly ladies of the place, and attended the subscription school; and the acknowledged leader of the band, who, belonging to the permanent irreducible staff of the establishment, was never off duty. we used to be very happy, and not altogether irrational, in these little skeleton parties. my new friend was a gentle, tasteful boy, fond of poetry, and a writer of soft, simple verses in the old-fashioned pastoral vein, which he never showed to any one save myself; and we learned to love one another all the more, from the circumstance that i was of a somewhat bold, self-relying temperament, and he of a clinging, timid one. two of the stanzas of a little pastoral, which he addressed to me about a twelvemonth after this time, when permanently quitting the north country for edinburgh, still remain fixed in my memory; and i must submit them to the reader, both as adequately representative of the many others, their fellows, which have been lost, and of that juvenile poetry in general which "is written," according to sir walter scott, "rather from the recollection of what has pleased the author in others, than what has been suggested by his own imagination." "to you my poor sheep i resign, my colly, my crook, and my horn: to leave you, indeed, i repine, but i must away with the morn. new scenes shall evolve on my sight, the world and its follies be new; but ah! can such scenes of delight ere arise, as i witnessed with you!" timid as he naturally was, he soon learned to abide in my company terrors which most of my bolder companions shrank from encountering. i was fond of lingering in the caves until long after nightfall, especially in those seasons when the moon at full, or but a few days in her wane, rose out of the sea as the evening wore on, to light up the wild precipices of that solitary shore, and to render practicable our ascending path to the hill above. and finlay was almost the only one of my band who dared to encounter with me the terrors of the darkness. our fire has often startled the benighted boatman as he came rowing round some rocky promontory, and saw the red glare streaming seawards from the cavern mouth, and partially lighting up the angry tumbling of the surf beyond; and excise-cutters have oftener than once altered their tack in middle firth, and come bearing towards the coast, to determine whether the wild rocks of marcus were not becoming a haunt of smugglers. immediately beyond the granitic gneiss of the hill there is a subaqueous deposit of the lias formation, never yet explored by geologist, because never yet laid bare by the ebb; though every heavier storm from the sea tells of its existence, by tossing ashore fragments of its dark bituminous shale. i soon ascertained that the shale is so largely charged with inflammable matter as to burn with a strong flame, as if steeped in tar or oil, and that i could repeat with it the common experiment of producing gas by means of a tobacco-pipe luted with clay. and, having read in shakspere of a fuel termed "sea-coal," and unaware at the time that the poet merely meant coal brought to london by sea, i inferred that the inflammable shale cast up from the depths of the firth by the waves could not be other than the veritable "sea-coal" which figured in the reminiscences of dame quickly; and so, assisted by finlay, who shared in the interest which i felt in the substance, as at once classical and an original discovery, i used to collect it in large quantities and convert it into smoky and troubled fires, that ever filled our cavern with a horrible stench, and scented all the shore. though unaware of the fact at the time, it owed its inflammability, not to vegetable, but to animal substance; the tar which used to boil in it to the heat, like resin in a fagot of moss-fir, was as strange a mixture as ever yet bubbled in witches' caldron--blood of pterodactyle and grease of ichthyosaur--eye of belemnite and hood of nautilus; and we learned to delight in its very smell, all oppressive as that was, as something wild, strange, and inexplicable. once or twice i seemed on the eve of a discovery: in splitting the masses, i occasionally saw what appeared to be fragments of shells embedded in its substance; and at least once i laid open a mysterious-looking scroll or volute, existing on the dark surface as a cream-coloured film; but though these organisms raised a temporary wonder, it was not until a later period that i learned to comprehend their true import, as the half-effaced but still decipherable characters of a marvellous record of the grey, dream-encircled past. with the docile finlay as my companion, and left to work out my own will unchallenged, i was rarely or never mischievous. on the occasions, however, in which my band swelled out to ten or a dozen, i often experienced the ordinary evils of leadership, as known in all gangs and parties, civil and ecclesiastical; and was sometimes led, in consequence, to engage in enterprises which my better judgment condemned. i fain wish that among the other "confessions" with which our literature is charged, we had the _bona fide_ "confessions of a leader," with examples of the cases in which, though he seems to overbear, he is in reality overborne, and actually follows, though he appears to lead. honest sir william wallace, though seven feet high, and a hero, was at once candid and humble enough to confess to the canons of hexham, that, his "soldiers being evil-disposed men," whom he could neither "justify nor punish," he was able to protect women and churchmen only so long as they "abided in his sight." and, of course, other leaders, less tall and less heroic, must not unfrequently find themselves, had they but wallace's magnanimity to confess the fact, in circumstances much akin to those of wallace. when bee-masters get hold of queen bees, they are able, by controlling the movements of these natural leaders of hives, to control the movements of the hives themselves; and not unfrequently in churches and states do there exist inconspicuous bee-masters, who, by influencing or controlling the leader-bees, in reality influence and control the movements of the entire body, politic or ecclesiastical, over which these natural monarchs seem to preside. but truce with apology. partly in the character of leader--partly being my self led--i succeeded about this time in getting one of my larger parties into a tolerably serious scrape. we passed every day, on our way to the cave, a fine large orchard, attached to the manor-house of the cromarty estate; and in ascending an adjacent hill over which our path lay, and which commands a bird's-eye view of the trim-kept walks and well-laden trees, there used not unfrequently to arise wild speculations among us regarding the possibility and propriety of getting a supply of the fruit, to serve as desserts to our meals of shell-fish and potatoes. weeks elapsed, however, and autumn was drawing on to its close, ere we could quite make up our minds regarding the adventure, when at length i agreed to lead; and, after arranging the plan of the expedition, we broke into the orchard under the cloud of night, and carried away with us whole pocketfuls of apples. they were all intolerably bad--sour, hard, baking apples; for we had delayed the enterprise until the better fruit had been pulled: but though they set our teeth on edge, and we flung most of them into the sea, we had "snatched" in the foray, what gray well terms "a fearful joy," and had some thought of repeating it, merely for the sake of the excitement induced and the risk encountered, when out came the astounding fact, that one of our number had "peached," and, in the character of king's evidence, betrayed his companions. the factor of the cromarty property had an orphan nephew, who formed at times a member of our gang, and who had taken a willing part in the orchard foray. he had also engaged, however, in a second enterprise of a similar kind wholly on his own account, of which we knew nothing. an out-house pertaining to the dwelling in which he lodged, though itself situated outside the orchard, was attached to another house inside the walls, which was employed by the gardener as a store-place for his apples; and finding an unsuspected crevice in the partition which divided the two buildings, somewhat resembling that through which pyramus and thisbe made love of old in the city of babylon, our comrade, straightway availing himself of so fair an opening, fell a-courting the gardener's apples. sharpening the end of a long stick, he began harpooning, through the hole, the apple-heap below; and though the hole was greatly too small for admitting the finer and larger specimens, and they, in consequence, fell back, disengaged from the harpoon, in the attempt to land them, he succeeded in getting a good many of the smaller ones. old john clark the gardener--far advanced in life at the time, and seeing too imperfectly to discover the crevice which opened high amid the obscurity of the loft--was in a perfect maze regarding the evil influence that was destroying his apples. the harpooned individuals lay scattered over the floor by scores; but the agent that had dispersed and perforated them remained for weeks together an inscrutable mystery to john. at length, however, there came a luckless morning, in which our quondam companion lost hold, when busy at work, of the pointed stick; and when john next entered his storehouse, the guilty harpoon lay stretched across the harpooned apples. the discovery was followed up; the culprit detected; and, on being closeted with his uncle the factor, he communicated not only the details of his own special adventure, but the particulars of ours also. and early next day there was a message sent us by a safe and secret messenger, to the effect that we would be all put in prison in the course of the week. we were terribly frightened; so much so, that the strong point of our position--the double-dyed guilt of the factor's nephew--failed to occur to any of us; and we looked for only instant incarceration. i still remember the intense feeling of shame i used to experience every time i crossed my mother's door for the street--the agonizing, all-engrossing belief that every one was looking at and pointing me out--and the terror, when in my uncles'--akin to that of the culprit who hears from his box the footsteps of the returning jury--that, having learned of my offence, they were preparing to denounce me as a disgrace to an honest family, on which, in the memory of man, no stain had before rested. the discipline was eminently wholesome, and i never forgot it. it did seem somewhat strange, however, that no one appeared to know anything about our misdemeanour: the factor kept our secret remarkably well; but we inferred he was doing so in order to pounce upon us all the more effectually; and, holding a hasty council in the cave, we resolved that, quitting our homes for a few weeks, we should live among the rocks till the storm that seemed rising should have blown by. marcus's cave was too accessible and too well known; but my knowledge of the locality enabled me to recommend to my lads two other caves in which i thought we might be safe. the one opened in a thicket of furze, some forty feet above the shore; and, though large enough within to contain from fifteen to twenty men, it presented outside much the appearance of a fox-earth, and was not known to half-a-dozen people in the country. it was, however, damp and dark; and we found that we could not venture on lighting a fire in it without danger of suffocation. it was pronounced excellent, however, as a temporary place of concealment, were the search for us to become very hot. the other cavern was wide and open; but it was a wild, ghostly-looking place, scarcely once visited from one twelvemonth's end to another: its floor was green with mould, and its ridgy walls and roof bristled over with slim pale stalactites, which looked like the pointed tags that roughen a dead-dress. it was certain, too, that it was haunted. marks of a cloven foot might be seen freshly impressed on its floor, which had been produced either by a stray goat, or by something worse; and the few boys to whom its existence and character were known used to speak of it under their breath as "the devil's cave." my lads did at first look round them as we entered, with an awe-struck and disconsolate expression; but falling busily to work among the cliffs, we collected large quantities of withered grass and fern for bedding, and, selecting the drier and less exposed portions of the floor, soon piled up for ourselves a row of little lairs, formed in a sort of half-way style between that of the wild beast and the gipsy, on which it would have been possible enough to sleep. we selected, too, a place for our fire, gathered a little heap of fuel, and secreted in a recess, for ready use, our marcus' cave pot and pitcher, and the lethal weapons of the gang, which consisted of an old bayonet so corroded with rust that it somewhat resembled a three-edged saw and an old horseman's pistol tied fast to the stock by cobbler's ends, and with lock and ramrod wanting. evening surprised us in the middle of our preparations; and as the shadows fell dark and thick, my lads began to look most uncomfortably around them. at length they fairly struck work: there was no use, they said, for being in the devil's cave so late--no use, indeed, for being in it at all, until we were made sure the factor did actually intend to imprison us; and, after delivering themselves to this effect, they fairly bolted, leaving finlay and myself to bring up the rear at our leisure. my well-laid plan was, in short, found unworkable, from the inferior quality of my materials. i returned home with a heavy heart, somewhat grieved that i had not confided my scheme to only finlay, who could, i ascertained, do braver things, with all his timidity, than the bolder boys, our occasional associates. and yet, when, in passing homewards through the dark lonely woods of the hill, i bethought me of the still deeper solitude and gloom of the haunted cave far below, and thought further, that at that very moment the mysterious being with the cloven foot might be traversing its silent floor, i felt my blood run cold, and at once leaped to the conclusion that, save for the disgrace, a cave with an evil spirit in it could be not a great deal better than a prison. of the prison, however, we heard no more; though i never forgot the grim but precious lesson read me by the factor's threat; and from that time till the present--save now and then, by inadvertently admitting into my newspaper a paragraph written in too terse a style by some good man in the provinces, against some very bad man his neighbour--i have not been fairly within wind of the law. i would, however, seriously advise such of my young friends as may cast a curious eye over these pages to avoid taking any such lesson as mine at first-hand. one half-hour of the mental anguish which i at this time experienced, when i thought of my mother and uncles, and the infamy of a prison, would have vastly more than counterbalanced all that could have been enjoyed from banqueting on apples, even had they been those of the hesperides or of eden, instead of being, what they were in this case, green masses of harsh acid, alike formidable to teeth and stomach. i must add, in justice to my friend of the doocot cave, that, though an occasional visitor at marcus, he had prudently avoided getting into this scrape. our long vacation came at length to an end, by the appointment of a teacher to the subscription school; but the arrangement was not the most profitable possible for the pupils. it was an ominous circumstance, that we learned in a few days to designate the new master by a nickname, and that the name stuck--a misfortune which almost never befalls the truly superior man. he had, however, a certain dash of cleverness about him; and observing that i was of potent influence among my school-fellows, he set himself to determine the grounds on which my authority rested. copy and arithmetic books, in schools in which there was liberty, used in those ancient times to be charged with curious revelations. in the parish school, for instance, which excelled, as i have said, every other school in the world in its knowledge of barques and carvels, it was not uncommon to find a book which, when opened at the right end, presented only copy-lines or arithmetical questions, that, when opened at the wrong one, presented only ships and boats. and there were cases on record in which, on the grand annual examination-day that heralded the vacation, the worthy parish minister, by beginning to turn over the leaves of some exhibited book at the reverse end, found himself engaged, when expecting only the questions of cocker, or the slip-lines of butterworth, amid whole fleets of smacks, frigates, and brigantines. my new master, professionally acquainted with this secret property of arithmetic and copy-books, laid hold of mine, and, bringing them to his desk, found them charged with very extraordinary revelations indeed. the blank spaces were occupied with deplorably scrabbled couplets and stanzas, blent with occasional remarks in rude prose, that dealt chiefly with natural phenomena. one note, for instance, which the master took the trouble of deciphering, referred to the supposed _fact_, familiar as a matter of sensation to boys located on the sea-coast, that during the bathing season the water is warmer in windy days, when the waves break high, than during dead calms; and accounted for it (i fear not very philosophically) on the hypothesis that the "waves, by slapping against each other, engender heat, as heat may be engendered by clapping the hands." the master read on, evidently with much difficulty, and apparently with considerable scepticism: he inferred that i had been borrowing, not inventing: though where such prose and such verse could have been borrowed, and, in especial, such grammar and such spelling, even cleverer men than he might well have despaired of ever finding out. and in order to test my powers, he proposed furnishing me with a theme on which to write. "let us see," he said, "let us see: the dancing-school ball comes on here next week--bring me a poem on the dancing-school ball." the subject did not promise a great deal; but, setting myself to work in the evening, i produced half-a-dozen stanzas on the ball, which were received as good, in evidence that i actually could rhyme; and for some weeks after i was rather a favourite with the new master. i had, however, ere now become a wild insubordinate boy, and the only school in which i could properly be taught was that world-wide school which awaited me, in which toil and hardship are the severe but noble teachers. i got into sad scrapes. quarrelling, on one occasion, with a boy of my own standing, we exchanged blows across the form; and when called up for trial and punishment, the fault was found to attach so equally to both sides, that the same number of _palmies_, well laid on, were awarded to each. i bore mine, however, like a north american indian, whereas my antagonist began to howl and cry; and i could not resist the temptation of saying to him in a whisper that unluckily reached the ear of the master, "ye big blubbering blockhead, take that for a drubbing from me." i had of course to receive a few palmies additional for the speech; but then, "who cared for that?" the master, however, "cared" considerably more for the offence than i did for the punishment. and in a subsequent quarrel with another boy--a stout and somewhat desperate mulatto--i got into a worse scrape still, of which he thought still worse. the mulatto, in his battles, which were many, had a trick, when in danger of being over-matched, of drawing his knife; and in our affair--the necessities of the fight seeming to require it--he drew his knife upon me. to his horror and astonishment, however, instead of running off, i immediately drew mine, and, quick as lightning, stabbed him in the thigh. he roared out in fright and pain, and, though more alarmed than hurt, never after drew knife upon a combatant. but the value of the lesson which i gave was, like most other very valuable things, inadequately appreciated; and it merely procured for me the character of being a dangerous boy. i had certainly reached a dangerous stage; but it was mainly myself that was in jeopardy. there is a transition-time in which the strength and independence of the latent man begin to mingle with the wilfulness and indiscretion of the mere boy, which is more perilous than any other, in which many more downward careers of recklessness and folly begin, that end in wreck and ruin, than in all the other years of life which intervene between childhood and old age. the growing lad should be wisely and tenderly dealt with at this critical stage. the severity that would fain compel the implicit submission yielded at an earlier period, would probably succeed, if his character was a strong one, in insuring but his ruin. it is at this transition-stage that boys run off to sea from parents and masters, or, when tall enough, enlist in the army for soldiers. the strictly orthodox parent, if more severe than wise, succeeds occasionally in driving, during this crisis, his son into popery or infidelity; and the sternly moral one, in landing _his_ in utter profligacy. but, leniently and judiciously dealt with, the dangerous period passes: in a few years at most--in some instances in even a few months--the sobriety incidental to a further development of character ensues, and the wild boy settles down into a rational young man. it so chanced, however, that in what proved the closing scene in my term of school attendance, i was rather unfortunate than guilty. the class to which i now belonged read an english lesson every afternoon, and had its rounds of spelling; and in these last i acquitted myself but ill; partly from the circumstance that i spelt only indifferently, but still more from the further circumstance, that, retaining strongly fixed in my memory the broad scotch pronunciation acquired at the dames' school, i had to carry on in my mind the double process of at once spelling the required word, and of translating the old sounds of the letters of which it was composed into the modern ones. nor had i been taught to break the words into syllables; and so, when required one evening to spell the word "_awful_," with much deliberation--for i had to translate, as i went on, the letters _a-w_ and _u_--i spelt it word for word, without break or pause, as a-w-f-u-l. "no," said the master, "a-w, _aw_, f-u-l, _awful_; spell again." this seemed preposterous spelling. it was sticking in an _a_, as i thought, into the middle of the word, where, i was sure, no _a_ had a right to be; and so i spelt it as at first. the master recompensed my supposed contumacy with a sharp cut athwart the ears with his tawse; and again demanding the spelling of the word, i yet again spelt it as at first. but on receiving a second cut, i refused to spell it any more; and, determined on overcoming my obstinacy, he laid hold of me and attempted throwing me down. as wrestling, however, had been one of our favourite marcus' cave exercises, and as few lads of my inches wrestled better than i, the master, though a tall and tolerably robust fellow, found the feat considerably more difficult than he could have supposed. we swayed from side to side of the school-room, now backwards, now forwards, and for a full minute it seemed to be rather a moot point on which side the victory was to incline. at length, however, i was tripped over a form; and as the master had to deal with me, not as master usually deals with pupil, but as one combatant deals with another, whom he has to beat into submission, i was mauled in a way that filled me with aches and bruises for a full month thereafter. i greatly fear that, had i met the fellow on a lonely road five years subsequent to our encounter, when i had become strong enough to raise breast-high the "great lifting stone of the dropping cave," he would have caught as sound a thrashing as he ever gave to little boy or girl in his life; but all i could do at this time was to take down my cap from off the pin, when the affair had ended, and march straight out of school. and thus terminated my school education. before night i had avenged myself, in a copy of satiric verses, entitled "the pedagogue," which--as they had some little cleverness in them, regarded as the work of a boy, and as the known eccentricities of their subject gave me large scope--occasioned a good deal of merriment in the place; and of the verses a fair copy, written out by finlay, was transmitted through the post-office to the pedagogue himself. but the only notice he ever took of them was incidentally, in a short speech made to the copyist a few days after. "i _see_, sir," he said,--"i _see_ you still associate with that fellow miller; perhaps he will make you a poet!" "i had thought, sir," said finlay very quietly, in reply, "that poets were born--not made." as a specimen of the rhyme of this period, and as in some degree a set-off against my drubbing, which remains till this day an unsettled score, i submit my pasquinade to the reader:-- the pedagogue. with solemn mien and pious air, s--k--r attends each call of grace; loud eloquence bedecks his prayer, and formal sanctity his face. all good; but turn the other side, and see the smirking beau displayed; the pompous strut, exalted air, and all that marks the fop, is there. in character we seldom see traits so diverse meet and agree: can the affected mincing trip, exalted brow, and pride-pressed lip, in strange incongruous union meet, with all that stamps the hypocrite? we see they do: but let us scan those secret springs which move the man. though now he wields the knotty birch, his better hope lies in the church: for this the sable robe he wears, for this in pious guise appears. but then, the weak will cannot hide th' inherent vanity and pride; and thus he acts the coxcomb's part, as dearer to his poor vain heart: nature's born fop! a saint by art!! but hold! he wears no fopling's dress each seam, each thread, the eye can trace his garb all o'er;--the dye, though true, time-blanch'd, displays a fainter hue: dress forms the fopling's better part; reconcile this, and prove your art. "chill penury represses pride;"-- a maxim by the wise denied; for 'tis alone tame plodding souls, whose spirits bend when it controls,-- whose lives run on in one dull same, plain honesty their highest aim. with him it merely can repress-- tailor o'er-cow'd--the pomp of dress; his spirit, unrepressed, can soar high as e'er folly rose before; can fly pale study, learn'd debate, and ape proud fashion's idle state: yet fails in that engaging grace that lights the practised courtier's face. his weak affected air we mark, and, smiling, view the would-be spark; complete in every act and feature,-- an ill-bred, silly, awkward creature. my school-days fairly over, a life of toil frowned full in front of me; but never yet was there a half-grown lad less willing to take up the man and lay down the boy. my set of companions was fast breaking up;--my friend of the doocot cave was on the eve of proceeding to an academy in a neighbouring town; finlay had received a call from the south, to finish his education in a seminary on the banks of the tweed; one marcus' cave lad was preparing to go to sea; another to learn a trade; a third to enter a shop; the time of dispersal was too evidently at hand; and, taking counsel one day together, we resolved on constructing something--we at first knew not what--that might serve as a monument to recall to us in after years the memory of our early pastimes and enjoyments. the common school-book story of the persian shepherd, who, when raised by his sovereign to high place in the empire, derived his chief pleasure from contemplating, in a secret apartment, the pipe, crook, and rude habiliments of his happier days, suggested to me that we also should have our secret apartment, in which to store up, for future contemplation, our bayonet and pistol, pot and pitcher; and i recommended that we should set ourselves to dig a subterranean chamber for that purpose among the woods of the hill, accessible, like the mysterious vaults of our story-books, by a trap-door. the proposal was favourably received; and, selecting a solitary spot among the trees as a proper site, and procuring spade and mattock, we began to dig. soon passing through the thin crust of vegetable mould, we found the red boulder clay beneath exceedingly stiff and hard; but day after day saw us perseveringly at work; and we succeeded in digging a huge square pit, about six feet in length and breadth, and fully seven feet deep. fixing four upright posts in the corners, we lined our apartment with slender spars nailed closely together; and we had prepared for giving it a massive roof of beams formed of fallen trees, and strong enough to bear a layer of earth and turf from a foot to a foot and a half in depth, with a little opening for the trap-door; when we found, one morning, on pressing onwards to the scene of our labours, that we were doggedly tracked by a horde of boys considerably more numerous than our own party. their curiosity had been excited, like that of the princess nekayah in rasselas, by the tools which we carried, and by "seeing that we had directed our walk every day to the same point;" and in vain, by running and doubling, by scolding and remonstrating, did we now attempt shaking them off. i saw that, were we to provoke a general _mélée_, we could scarce expect to come off victors; but deeming myself fully a match for their stoutest boy, i stepped out and challenged him to come forward and fight me. he hesitated, looked foolish, and refused; but said, he would readily fight with any of my party except myself. i immediately named my friend of the doocot cave, who leaped out with a bound to meet him; but the boy, as i had anticipated, refused to fight him also; and, observing the proper effect produced, i ordered my lads to march forward; and from an upper slope of the hill we had the satisfaction of seeing that our pursuers, after lingering for a little while on the spot on which we had left them, turned homewards, fairly cowed, and pursued us no more. but, alas! on reaching our secret chamber, we ascertained, by marks all too unequivocal, that it was to be secret no longer. some rude hand had torn down the wooden lining, and cut two of the posts half through with a hatchet; and on returning disconsolately to the town, we ascertained that johnstone the forester had just been there before us, declaring that some atrociously wicked persons--for whose apprehension a proclamation was to be instantly issued--had contrived a diabolical trap, which he had just discovered, for maiming the cattle of the gentleman, his employer, who farmed the hill. johnstone was an old forty-second man, who had followed wellington over the larger part of the peninsula; but though he had witnessed the storming and sack of san sebastian, and a great many other bad things, nothing had he ever seen on the peninsula, or anywhere else, he said, half so mischievous as the cattle-trap. we, of course, kept our own secret; and as we all returned under the cloud of night, and with heavy hearts filled up our excavation level with the soil, the threatened proclamation was never issued. johnstone, however--who had been watching my motions for a considerable time before, and whom, as he was a formidable fellow, very unlike any of the other foresters, i had been sedulously watching in turn--had no hesitation in declaring that i, and i only, could be the designer of the cattle-trap. i had acquainted myself in books, he said, with the mode of entrapping by pitfalls wild beasts in the forests abroad; and my trap for the colonel's cattle was, he was certain, a result of my book-acquired knowledge. i was one day lounging in front of my mother's dwelling, when up came johnstone to address me. as the evidence regarding the excavation had totally broken down, i was aware of no special offence at the time that could have secured for me such a piece of attention, and inferred that the old soldier was labouring under some mistake; but johnstone's address soon evinced that he was not in the least mistaken. "he wished to be acquainted with me," he said. "it was all nonsense for us to be bothering one another, when we had no cause to quarrel." he used occasionally to eke out his pension, and his scanty allowance as forester, by catching a basket of fish for himself from off the rocks of the hill; and he had just discovered a projecting rock at the foot of a tall precipice, which would prove, he was sure, one of the best fishing platforms in the firth. but then, in the existing state, it was wholly inaccessible. he was, however, of opinion, that it was possible to lay it open by carrying a path adown the shelving face of the precipice. he had seen wellington address himself to quite as desperate-looking matters in the peninsula; and were i but to assist him, he was sure, he said, we could construct between us the necessary path. the undertaking was one wholly according to my own heart; and next morning johnstone and i were hard at work on the giddy brow of the precipice. it was topped by a thick bed of boulder clay, itself--such was the steepness of the slope--almost a precipice; but a series of deeply-cut steps led us easily adown the bed of clay; and then a sloping shelf, which, with much labour, we deepened and flattened, conducted us not unsafely some five-and-twenty or thirty feet along the face of the precipice proper. a second series of steps, painfully scooped out of the living rock, and which passed within a few yards of a range of herons' nests perched on a hitherto inaccessible platform, brought us down some five-and-twenty or thirty feet more; but then we arrived at a sheer descent of about twenty feet, at which johnstone looked rather blank, though, on my suggesting a ladder, he took heart again, and, cutting two slim taper trees in the wood above, we flung them over the precipice into the sea; and then fishing them up with a world of toil and trouble, we squared and bored them upwards, and, cutting tenons for them in the hard gneiss, we placed them against the rock front, and nailed over them a line of steps. the precipice beneath sloped easily on to the fishing rock, and so a few steps more completed our path. i never saw a man more delighted than johnstone. as being lighter and more active than he--for though not greatly advanced in life, he was considerably debilitated by severe wounds--i had to take some of the more perilous parts of the work on myself. i had cut the tenons for the ladder with a rope round my waist, and had recovered the trees flung into the sea by some adroit swimming; and the old soldier became thoroughly impressed with the conviction that my proper sphere was the army. i was already five feet three, he said; in little more than a twelvemonth i would be five feet seven; and were i then but to enlist, and to keep from the "drop drink"--a thing which he never could do--i would, he was certain, rise to be a serjeant. in brief, such were the terms on which johnstone and i learned to live ever after, that, had i constructed a _score_ of traps for the colonel's cattle, i believe he would have winked at them all. poor fellow! he got into difficulties a good many years after, and, on the accession of the whigs to power, mortgaged his pension, and emigrated to canada. deeming the terms hard, however, as he well might, he first wrote a letter to his old commander, the duke of wellington--i holding the pen for him--in which, in the hope that their stringency might be relaxed in his behalf, he stated both his services and his case. and promptly did the duke reply, in an essentially kind holograph epistle, in which, after stating that he had no influence at the time with the ministers of the crown, and no means of getting a relaxation of their terms in behalf of any one, he "earnestly recommended william johnstone, _first_, not to seek a provision for himself in canada, unless he were able-bodied, and fit to provide for himself in circumstances of extreme hardship; and, _second_, on no account to sell or mortgage his pension." but the advice was not taken;--johnstone did emigrate to canada, and did mortgage his pension; and i fear--though i failed to trace his after history--that he suffered in consequence. chapter viii. "now, surely, thought i, there's enou to fill life's dusty way; and who will miss a poet's feet, or wonder where he stray! so to the woods and wastes i'll go, and i will build an ozier bower; and sweetly there to me shall flow the meditative hour."--henry kirke white. finlay was away; my friend of the doocot cave was away; my other companions were all scattered abroad; my mother, after a long widowhood of more than eleven years, had entered into a second marriage; and i found myself standing face to face with a life of labour and restraint. the prospect appeared dreary in the extreme. the necessity of ever toiling from morning to night, and from one week's end to another, and all for a little coarse food and homely raiment, seemed to be a dire one; and fain would i have avoided it. but there was no escape; and so i determined on being a mason. i remembered my cousin george's long winter holidays, and how delightfully he employed them; and, by making choice of cousin george's profession, i trusted to find, like him, large compensation, in the amusements of one-half the year, for the toils of the other half. labour shall not wield over me, i said, a rod entirely black, but a rod like one of jacob's peeled wands, chequered white and black alternately. i however, did look, even at this time, notwithstanding the antecedents of a sadly mis-spent boyhood, to something higher than mere amusement; and, daring to believe that literature, and, mayhap, natural science, were, after all, my proper vocations, i resolved that much of my leisure time should be given to careful observation, and the study of our best english authors. both my uncles, especially james, were sorely vexed by my determination to be a mason; they had expected to see me rising in some one of the learned professions; yet here was i going to be a mere operative mechanic, like one of themselves! i spent with them a serious hour, in which they urged that, instead of entering as a mason's apprentice, i should devote myself anew to my education. though the labour of their hands formed their only wealth, they would assist me, they said, in getting through college; nay, if i preferred it, i might meanwhile come and live with them: all they asked of me in return was that i should give myself as sedulously to my lessons as, in the event of my becoming a mason, i would have to give myself to my trade. i demurred. the lads of my acquaintance, who were preparing for college had an eye, i said, to some profession; they were qualifying themselves to be lawyers, or medical men, or, in much larger part, were studying for the church; whereas i had no wish, and no peculiar fitness to be either lawyer or doctor; and as for the church, that was too serious a direction to look in for one's bread, unless one could honestly regard one's-self as _called_ to the church's proper work; and i could not. there, said my uncles, you are perfectly right: better be a poor mason--better be anything honest, however humble--than an _uncalled_ minister. how very strong the hold taken of the mind in some cases by hereditary convictions of which the ordinary conduct shows little apparent trace! i had for the last few years been a wild boy--not without my share of respect for donald roy's religion, but possessed of none of donald's seriousness; and yet here was his belief in this special matter lying so strongly entrenched in the recesses of my mind, that no consideration whatever could have induced me to outrage it by obtruding my unworthiness on the church. though, mayhap, overstrained in many of its older forms, i fain wish the conviction, in at least some of its better modifications, were more general now. it might be well for all the protestant churches practically to hold, with uncles james and sandy, that true ministers cannot be manufactured out of ordinary men--men ordinary in talent and character--in a given number of years, and then passed by the imposition of hands into the sacred office; but that, on the contrary, ministers, when real, are all special creations of the grace of god. i may add, that in a belief of this kind, deeply implanted in the popular mind of scotland, the strength of our recent church controversy mainly lay. slowly and unwillingly my uncles at length consented that i should make trial of a life of manual labour. the husband of one of my maternal aunts was a mason, who, contracting for jobs on a small scale, usually kept an apprentice or two, and employed a few journeymen. with him i agreed to serve for the term of three years; and, getting a suit of strong moleskin clothes, and a pair of heavy hob-nailed shoes, i waited only for the breaking up of the winter frosts, to begin work in the cromarty quarries--jobbing masters in the north of scotland usually combining the profession of the quarrier with that of the mason. in the beautiful poetic fragment from which i have chosen my motto, poor kirke white fondly indulges in the dream of a hermit life--quiet, meditative, solitary, spent far away in deep woods, or amid wide-spread wastes, where the very sounds that arose would be but the faint echoes of a loneliness in which man was not--a "voice of the desert, never dumb." the dream is that of a certain brief period of life between boyhood and comparatively mature youth; and we find more traces of it in the poetry of kirke white than in that of almost any other poet; simply because he wrote at the age in which it is natural to indulge in it, and because, being less an imitator, and more original, than most juvenile poets, he gave it as portion of the internal experience from which he drew. but it is a dream not restricted to young poets: the ignorant, half-grown lad, who learns, for the first time, "about the great rich gentleman who advertises for a hermit," and wishes that he had but the necessary qualification of beard to offer himself as a candidate, indulges in it also; and i, too, in this transition stage, cherished it with all the strength of a passion. it seems to spring out of a latent timidity in the yet undeveloped mind, that shrinks from grappling with the stern realities of life, amid the crowd and press of the busy world, and o'ershaded by the formidable competition of men already practised in the struggle. i have still before me the picture of the "lodge in some vast wilderness" to which i could have fain retired, to lead all alone a life quieter, but quite as wild, as my marcus' cave one; and the snugness and comfort of the humble interior of my hermitage, during some boisterous night of winter, when the gusty wind would be howling around the roof, and the rain beating on the casement, but when, in the calm within, the cheerful flame would roar in the chimney, and glance bright on rafter and wall, still impress me as if the recollection were in reality that of a scene witnessed, not of a mere vision conjured up by the fancy. but it was all the idle dream of a truant lad, who would fain now, as on former occasions, have avoided going to school--that best and noblest of all schools, save the christian one, in which honest labour is the teacher--in which the ability of being useful is imparted, and the spirit of independence communicated, and the habit of persevering effort acquired; and which is more moral than the schools in which only philosophy is taught, and greatly more happy than the schools which profess to teach only the art of enjoyment. noble, upright, self-relying toil! who that knows thy solid worth and value would be ashamed of thy hard hands, and thy soiled vestments, and thy obscure tasks--thy humble cottage, and hard couch, and homely fare! save for thee and thy lessons, man in society would everywhere sink into a sad compound of the fiend and the wild beast; and this fallen world would be as certainly a moral as a natural wilderness. but i little thought of the excellence of thy character and of thy teachings, when, with a heavy heart, i set out about this time, on a morning of early spring, to take my first lesson from thee in a sandstone quarry. i have elsewhere recorded the history of my few first days of toil; but it is possible for two histories, of the same period and individual, to be at once true to fact, and unlike each other in the scenes which they describe, and the events which they record. the quarry in which i commenced my life of labour was, as i have said, a sandstone one, and exhibited in the section of the furze-covered bank which it presented, a bar of deep red stone beneath, and a bar of pale red clay above. both deposits belonged to formations equally unknown, at the time, to the geologist. the deep-red stone formed part of an upper member of the lower old red sandstone; the pale red clay, which was much roughened by rounded pebbles, and much cracked and fissured by the recent frosts, was a bed of the boulder clay. save for the wholesome restraint that confined me for day after day to this spot, i should perhaps have paid little attention to either. mineralogy, in its first rudiments, had early awakened my curiosity, just as it never fails to awaken, with its gems and its metals, and its hard glittering rocks, of which tools may be made, the curiosity of infant tribes and nations. but in unsightly masses of mechanical origin, whether sandstone or clay, i could take no interest; just as infant societies take no interest in such masses, and so fail to know anything of geology; and it was not until i had learned to detect among the ancient sandstone strata of this quarry exactly the same phenomena as those which i used to witness in my walks with uncle sandy in the ebb, that i was fairly excited to examine and inquire. it was the necessity which made me a quarrier that taught me to be a geologist. further, i soon found that there was much to be enjoyed in a life of labour. a taste for the beauties of natural scenery is of itself a never-failing spring of delight; and there was scarce a day in which i wrought in the open air, during this period, in which i did not experience its soothing and exhilarating influence. well has it been said by the poet keats, that "a thing of beauty is a joy for ever." i owed much to the upper reaches of the cromarty firth, as seen, when we sat down to our mid-day meal, from the gorge of the quarry, with their numerous rippling currents, that, in the calm, resembled streamlets winding through a meadow, and their distant grey promontories tipped with villages that brightened in the sunshine; while, pale in the background, the mighty hills, still streaked with snow, rose high over bay and promontory, and gave dignity and power to the scene. still, however, with all my enjoyments, i had to suffer some of the evils of excessive toil. though now seventeen, i was still seven inches short of my ultimate stature; and my frame, cast more at the time in the mould of my mother than in that of the robust sailor, whose "back," according to the description of one of his comrades, "no one had ever put to the ground," was slim and loosely knit; and i used to suffer much from wandering pains in the joints, and an oppressive feeling about the chest, as if crushed by some great weight. i became subject, too, to frequent fits of extreme depression of spirits, which took almost the form of a walking sleep--results, i believe, of excessive fatigue--and during which my absence of mind was so extreme, that i lacked the ability of protecting myself against accident, in cases the most simple and ordinary. besides other injuries, i lost at different times during the first few months of my apprenticeship, when in these fits of partial somnambulism, no fewer than seven of my finger-nails. but as i gathered strength, my spirits became more equable; and not until many years after, when my health failed for a time under over-exertion of another kind, had i any renewed experience of the fits of walking sleep. my master, an elderly man at the time--for, as he used not unfrequently to tell his apprentices, he had been born on the same day and year as george the fourth, and so we could celebrate, if we pleased, both birthdays together--was a person of plodding, persevering industry, who wrought rather longer hours than was quite agreeable to one who wished to have some time to himself; but he was, in the main, a good master. as a builder, he made conscience of every stone he laid. it was remarked in the place, that the walls built by uncle david never bulged or fell; and no apprentice or journeyman of his was permitted, on any plea, to make "slight wark." though by no means a bold or daring man, he was, from sheer abstraction, when engrossed in his employment, more thoroughly insensible to personal danger than almost any other individual i ever knew. on one occasion, when an overloaded boat, in which he was carrying stones from the quarry to the neighbouring town, was overtaken by a series of rippling seas, and suddenly sank, leaving him standing on one of the thwarts submerged to the throat, he merely said to his partner, on seeing his favourite snuff-mull go floating past, "od, andro man, just rax out your han' and tak' in my snuff-box." on another, when a huge mass of the boulder clay came toppling down upon us in the quarry with such momentum, that it bent a massive iron lever like a bow, and crushed into minute fragments a strong wheelbarrow, uncle david, who, older and less active than any of the others, had been entangled in the formidable debris, relieved all our minds by remarking, as we rushed back, expecting to find him crushed as flat as a botanical preparation, "od, i draid, andro man, we have lost our good barrow." he was at first of opinion that i would do him little credit as a workman: in my absent fits i was well-nigh as impervious to instruction as he himself was insensible to danger; and i laboured under the further disadvantage of knowing a little, as an amateur, of both hewing and building, from the circumstance, that when the undertakings of my schoolboy days involved, as they sometimes did, the erection of a house, i used always to be selected as the mason of the party. and all that i had learned on these occasions i had now to unlearn. in the course of a few months, however, i did unlearn it all; and then, acquiring in less than a fortnight a very considerable mastery over the mallet--for mine was one of the not unfrequent cases in which the mechanical knock seems, after many an abortive attempt, to be caught up at once--i astonished uncle david one morning by setting myself to compete with him, and by hewing nearly two feet of pavement for his one. and on this occasion my aunt, his wife, who had been no stranger to his previous complaints, was informed that her "stupid nephew" was to turn out "a grand workman after all." a life of toil has, however, its peculiar temptations. when overwrought, and in my depressed moods, i learned to regard the ardent spirits of the dram-shop as high luxuries: they gave lightness and energy to both body and mind, and substituted for a state of dulness and gloom, one of exhilaration and enjoyment. usquebaugh was simply happiness doled out by the glass, and sold by the gill. the drinking usages of the profession in which i laboured were at this time many: when a foundation was laid, the workmen were treated to drink; they were treated to drink when the walls were levelled for laying the joists; they were treated to drink when the building was finished; they were treated to drink when an apprentice joined the squad; treated to drink when his "apron was washed;" treated to drink when "his time was out;" and occasionally they learned to treat one another to drink. in laying down the foundation-stone of one of the larger houses built this year by uncle david and his partner, the workmen had a royal "founding-pint," and two whole glasses of the whisky came to my share. a full-grown man would not have deemed a gill of usquebaugh an overdose, but it was considerably too much for me; and when the party broke up, and i got home to my books, i found, as i opened the pages of a favourite author, the letters dancing before my eyes, and that i could no longer master the sense. i have the volume at present before me--a small edition of the essays of bacon, a good deal worn at the corners by the friction of the pocket; for of bacon i never tired. the condition into which i had brought myself was, i felt, one of degradation. i had sunk, by my own act, for the time, to a lower level of intelligence than that on which it was my privilege to be placed; and though the state could have been no very favourable one for forming a resolution, i in that hour determined that i should never again sacrifice my capacity of intellectual enjoyment to a drinking usage; and, with god's help, i was enabled to hold by the determination. though never a strict abstainer, i have wrought as an operative mason for whole twelvemonths together, in which i did not consume half-a-dozen glasses of ardent spirits, or partake of half-a-dozen draughts of fermented liquor. but i do see, in looking back on this my first year of labour, a dangerous point, at which, in the attempt to escape from the sense of depression and fatigue, the craving appetite of the confirmed tippler might have been formed. the ordinary, long-wrought quarries of my native town have been opened in the old coast-line along the southern shores of the cromarty firth, and they contain no organisms. the beds occasionally display their water-rippled surfaces, and occasionally their areas of ancient desiccation, in which the polygonal partings still remain as when they had cracked in the drying, untold ages before. but the rock contains neither fish nor shell; and the mere mechanical processes of which it gave evidence, though they served to raise strange questions in my mind, failed to interest me so deeply as the wonderful organisms of other creations would have done. we soon quitted these quarries, however, as they proved more than usually difficult in the working at this time, for a quarry situated on the northern shore of the moray firth, which had been recently opened in an inferior member of the lower old red sandstone, and which, as i subsequently ascertained, does in some of its beds contain fossils. it was, however, not to the quarry itself that my first-found organisms belonged. there lies in the firth beyond, an outlier of the lias, which, like the marcus' cave one referred to in a preceding chapter, strews the beach with its fragments after every storm from the sea; and in a nodular mass of bluish-grey limestone derived from this subaqueous bed i laid open my first-found ammonite. it was a beautiful specimen, graceful in its curves as those of the ionic volute, and greatly more delicate in its sculpturing; and its bright cream-coloured tint, dimly burnished by the prismatic hues of the original pearl, contrasted exquisitely with the dark grey of the matrix which enclosed it. i broke open many a similar nodule during our stay at this delightful quarry, and there were few of them in which i did not detect some organism of the ancient world--scales of fishes, groups of shells, bits of decayed wood, and fragments of fern. at the dinner hour i used to show my new-found specimens to the workmen; but though they always took the trouble of looking at them, and wondered at times how the shells and plants had "got into the stones," they seemed to regard them as a sort of natural toys, which a mere lad might amuse himself in looking after, but which were rather below the notice of grown-up people like themselves. one workman, however, informed me, that things of a kind i had not yet found--genuine thunderbolts--which in his father's times were much sought for the cure of bewitched cattle--were to be found in tolerable abundance on a reach of the beach about two miles further to the west; and as, on quitting the quarry for the piece of work on which we were to be next engaged, uncle david gave us all a half-holiday, i made use of it in visiting the tract of shore indicated by the workman. and there, leaning against the granitic gneiss and hornblend slate of the hill of eathie, i found a liassic deposit, amazingly rich in its organisms--not buried under the waves, as at marcus' shore, or as opposite our new quarry, but at one part underlying a little grass-covered plain, and at another exposed for several hundred yards together along the shore. never yet did embryo geologist break ground on a more promising field; and memorable in my existence was this first of the many happy evenings that i have spent in exploring it. the hill of eathie, like the cromarty sutors, belongs, as i have already had occasion to mention, to what de beaumont would term the ben nevis system of hills--that latest of our scottish mountain systems which, running from south-west to north-east, in the line of the great caledonian valley, and in that of the valleys of the nairn, findhorn, and spey, uptilted in its course, when it arose, the oolites of sutherland, and the lias of cromarty and ross. the deposit which the hill of eathie disturbed is exclusively a liassic one. the upturned base of the formation rests immediately against the hill; and we may trace the edges of the various overlying beds for several hundred feet outwards, until, apparently near the top of the deposit, we lose them in the sea. the various beds--all save the lowest, which consists of a blue adhesive clay--are composed of a dark shale, consisting of easily-separable laminæ, thin as sheets of pasteboard; and they are curiously divided from each other by bands of fossiliferous limestone of but from one to two feet thick. these liassic beds, with their separating bands, are a sort of boarded books; for as a series of volumes reclining against a granite pedestal in the geologic library of nature, i used to find pleasure in regarding them. the limestone bands, elaborately marbled with lignite, ichthyolite, and shell, form the stiff boarding; the pasteboard-like laminæ between--tens and hundreds of thousands in number in even the slimmer volumes--compose the closely-written leaves. i say closely written; for never yet did signs or characters lie closer on page or scroll than do the organisms of the lias on the surface of these leaf-like laminæ. i can scarce hope to communicate to the reader, after the lapse of so many years, an adequate idea of the feeling of wonder which the marvels of this deposit excited in my mind, wholly new as they were to me at the time. even the fairy lore of my first-formed library--that of the birchen box--had impressed me less. the general tone of the colouring of these written leaves, though dimmed by the action of untold centuries, is still very striking. the ground is invariably of a deep neutral grey, verging on black; while the flattened organisms, which present about the same degree of relief as one sees in the figures of an embossed card, contrast with it in tints that vary from opaque to silvery white, and from pale yellow to an umbry or chestnut brown. groups of ammonites appear as if drawn in white chalk; clusters of a minute undescribed bivalve are still plated with thin films of the silvery nacre; the mytilaceæ usually bear a warm tint of yellowish brown, and must have been brilliant shells in their day; gryphites and oysters are always of a dark grey, and plagiostomæ ordinarily of a bluish or neutral tint. on some of the leaves curious pieces of incident seem recorded. we see fleets of minute terebratulæ, that appear to have been covered up by some sudden deposit from above, when riding at their anchors; and whole argosies of ammonites, that seemed to have been wrecked at once by some untoward accident, and sent crushed and dead to the bottom. assemblages of bright black plates, that shine like pieces of japan work, with numerous parallelogrammical scales bristling with nail-like points, indicate where some armed fish of the old ganoid order lay down and died; and groups of belemnites, that lie like heaps of boarding-pikes thrown carelessly on a vessel's deck on the surrender of the crew, tell where _skulls_ of cuttle-fishes of the ancient type had ceased to trouble the waters. i need scarce add, that these spear-like belemnites formed the supposed thunderbolts of the deposit. lying athwart some of the pages thus strangely inscribed we occasionally find, like the dark hawthorn leaf in bewick's well-known vignette, slim-shaped leaves coloured in deep umber; and branches of extinct pines, and fragments of strangely-fashioned ferns, form their more ordinary garnishing. page after page, for tens and hundreds of feet together, repeat the same wonderful story. the great alexandrian library, with its tomes of ancient literature, the accumulation of long ages, was but a meagre collection--not less puny in bulk than recent in date--compared with this marvellous library of the scotch lias. who, after once spending even a few hours in such a school, could avoid being a geologist? i had formerly found much pleasure among rocks and in caves; but it was the wonders of the eathie lias that first gave direction and aim to my curiosity. from being a mere child, that had sought amusement in looking over the _pictures_ of the stony volume of nature, i henceforth became a sober student desirous of reading and knowing it as a book. the extreme beauty, however, of the liassic fossils made me pass over at this time, as of little interest, a discovery which, if duly followed up, would have probably landed me full in the midst of the old red sandstone ichthyolites fully ten years ere i learned to know them. in forming a temporary harbour, at which we boated the stones we had been quarrying, i struck my pick into a slaty sandstone bed, thickly mottled in the layers by carbonaceous markings. they consisted, i saw, of thin rectilinear stems or leaves, much broken and in a bad state of keeping, that at once suggested to me layers of comminuted _zostera marina_, such as i had often seen on the cromarty beach thrown up from the submarine meadows of the firth beyond. but then, with magnificent ammonites and belemnites, and large well-marked lignites, to be had in abundance at eathie just for the laying open and the picking up, how could i think of giving myself to disinter what seemed to be mere broken fragments of _zostera_? within, however, a few feet of these carbonaceous markings there occurred one of those platforms of violent death for which the old red sandstone is so remarkable--a platform strewed over with fossil remains of the firstborn ganoids of creation, many of which still bore in their contorted outlines evidence of sudden dissolution and the dying pang. during the winter of this year--for winter at length came, and, my labours over, three happy months were all my own--i had an opportunity of seeing, deep in a wild highland glen, the remains of one of our old scotch forests of the native pine. my cousin george, finding his pretty highland cottage on the birch-covered tomhan situated too far from his ordinary scenes of employment, had removed to cromarty; and when his work had this year come to a close for the season, he made use of his first leisure in visiting his father-in-law, an aged shepherd who resided in the upper recesses of strathcarron. he had invited me to accompany him; and of the invitation i gladly availed myself. we struck across the tract of wild hills which intervenes between the cromarty and dornoch firths, a few miles to the west of the village of invergordon; and after spending several hours in toiling across dreary moors, unopened at the time by any public road, we took our noon-day refreshment in an uninhabited valley, among broken cottage walls, with a few furrowed patches stretching out around us, green amid the waste. one of the best swordsmen in ross had once lived there; but both he and his race had been lost to scotland in consequence of the compelled emigration so common in the highlands during the last two ages; and cousin george came strongly out against the lairds. the chill winter night had fallen on the dark hills and alder-skirted river of strathcarron, as, turning from off the road that winds along the kyle of dornoch, we entered its bleak gorge; and as the shepherd's dwelling lay high up the valley, where the lofty sides approach so near, and rise so abruptly, that for the whole winter quarter the sun never falls on the stream below, we had still some ten or twelve miles of broken road before us. the moon, in her first quarter, hung on the edge of the hills, dimly revealing their rough outline; while in a recess of the stream, far beneath, we could see the torch of some adventurous fisher, now gleaming red on rock and water, now suddenly disappearing, eclipsed by the overhanging brushwood. it was late ere we reached the shepherd's cottage--a dark-raftered, dimly-lighted erection of turf and stone. the weather for several weeks before had been rainy and close, and the flocks of the inmate had been thinned by the common scourge of the sheep-farmer at such seasons on damp, boggy farms. the beams were laden with skins besmeared with blood, that dangled overhead to catch the conservative influences of the smoke; and on a rude plank-table below, there rose two tall pyramids of braxy-mutton, heaped up each on a corn-riddle. the shepherd--a highlander of large proportions, but hard, and thin, and worn by the cares and toils of at least sixty winters--sat moodily beside the fire. the state of his flocks was not cheering; and, besides, he had seen a vision of late, he said, that filled his mind with strange forebodings. he had gone out after nightfall on the previous evening to a dank hollow, in which many of his flock had died. the rain had ceased a few hours before, and a smart frost had set in, and filled the whole valley with a wreath of silvery vapour, dimly lighted by the thin fragment of a moon that appeared as if resting on the hill-top. the wreath stretched out its grey folds beneath him--for he had climbed half-way up the acclivity--when suddenly the figure of a man, formed as of heated metal--the figure of what seemed to be a brazen man brought to a red heat in a furnace--sprang up out of the darkness; and, after stalking over the surface of the fog for a few brief seconds, during which, however, it had traversed the greater part of the valley, it as suddenly disappeared, leaving an evanescent trail of flame behind it. there could be little doubt that the old shepherd had merely seen one of those shooting lights that in mountain districts so frequently startle the night traveller; but the apparition now filled his whole mind, as one vouchsafed from the spiritual world, and of strange and frightful portent:-- "a meteor of the night of distant years, that flashed unnoticed, save by wrinkled eld, musing at midnight upon prophecies." i spent the greater part of the following day with my cousin in the forest of corrybhalgan, and saw two large herds of red deer on the hills. the forest was but a shred of its former self; but the venerable trees still rose thick and tall in some of the more inaccessible hollows; and it was interesting to mark, where they encroached furthest on the open waste, how thoroughly they lost the ordinary character of the scotch fir, and how, sending out from their short gnarled boles immense branches, some two or three feet over the soil, they somewhat resembled in their squat, dense proportions, and rounded contours, gigantic bee-hives. it was of itself worth while undertaking a journey to the highlands, to witness these last remains of that arboreous condition of our country to which the youngest of our geological formations, the peat mosses, bear such significant witness; and which still, largely existing as the condition of the northern countries of continental europe, "remains to attest," as humboldt well remarks, "more than even the records of history, the youthfulness of our civilisation." i revisited at this time, before returning home, the barony of gruids; but winter had not improved it: its humble features, divested of their summer complexion, had assumed an expression of blank wretchedness; and hundreds of its people, appalled at the time by a summons of ejection, looked quite as depressed and miserable as its scenery. finlay and my friend of the doocot cave were no longer within reach; but during this winter i was much in the company of a young man about five years my senior, who was of the true stuff of which friends are made, and to whom i became much attached. i had formed some acquaintance with him about five years before, on his coming to the place from the neighbouring parish of nigg, to be apprenticed to a house-painter, who lived a few doors from my mother's. but there was at first too great a disparity between us for friendship; he was a tall lad, and i a wild boy; and, though occasionally admitted into his sanctum--a damp little room in an outhouse in which he slept, and in his leisure hours made water-colour drawings and verses--it was but as an occasional visitor, who, having a rude taste for literature and the fine arts, was just worthy of being encouraged in this way. my year of toil had, however, wrought wonders for me: it had converted me into a sober young man; and william ross now seemed to find scarce less pleasure in my company than i did in his. poor william! his name must be wholly unfamiliar to the reader; and yet he had that in him which ought to have made it a known one. he was a lad of genius--drew truthfully, had a nice sense of the beautiful, and possessed the true poetic faculty; but he lacked health and spirits, and was naturally of a melancholy temperament, and diffident of himself. he was at this time a thin, pale lad, fair-haired, with a clear waxen complexion, flat chest, and stooping figure; and though he lasted considerably longer than could have been anticipated from his appearance, in seven years after he was in his grave. he was unfortunate in his parents; his mother, though of a devout family of the old scottish type, was an aberrant specimen;--she had fallen in early youth, and had subsequently married an ignorant, half-imbecile labourer, with whom she passed a life of poverty and unhappiness; and of this unpromising marriage william was the eldest child. it was certainly not from either parent he derived his genius. his maternal grandmother and aunt were, however, excellent christian women of superior intelligence, who supported themselves by keeping a girls' school in the parish; and william, who had been brought at an early age to live with them, and was naturally a gentle-spirited, docile boy, had the advantage, in consequence, of having that most important lesson of any education--the lesson of a good example at home--set well before him. his boyhood had been that of the poet: he had loved to indulge in his day-dreams in the solitude of a deep wood beside his grandmother's cottage; and had learned to write verses and draw landscapes in a rural locality in which no one had ever written verses or drawn landscapes before. and finally, as, in the north of scotland, in those primitive times, the nearest approach to an artist was a house-painter, william was despatched to cromarty, when he had grown tall enough for the work, to cultivate his natural taste for the fine arts, in papering rooms and lobbies, and in painting railings and wheel-barrows. there are, i believe, a few instances on record of house-painters rising to be artists: the history of the late mr. william bonnar, of the royal academy of edinburgh, furnishes one of these; but the fact that the cases are not more numerous serves, i fear, to show how much oftener a turn for drawing is a merely imitative, than an original, self-derived faculty. almost all the apprentices of our neighbour the house-painter had their turn for drawing decided enough to influence their choice of a profession; and what was so repeatedly the case in cromarty must, i should think, have been the case in many similar places; but of how few of these embryo limners have the works appeared in even a provincial exhibition-room! at the time my intimacy with william became most close, both his grandmother and aunt were dead, and he was struggling with great difficulty through the last year of his apprenticeship. as his master supplied him with but food and lodging, his linen was becoming scant, and his sabbath suit shabby; and he was looking forward to the time when he should be at liberty to work for himself, with all the anxiety of the voyager who fears that his meagre stock of provisions and water may wholly fail him ere he reaches port. i of course could not assist him. i was an apprentice like himself, and had not the command of a sixpence; nor, had the case been otherwise, would he in all probability have consented to accept of my help; but he lacked spirits as much as money, and in that particular my society did him good. we used to beat over all manner of subjects together, especially poetry and the fine arts; and though we often differed, our differences served only to knit us the more. he, for instance, deemed the "minstrel" of beattie the most perfect of english poems; but though he liked dryden's "virgil" well enough, he could find no poetry whatever in the "absalom and ahithophel" of dry den; whereas i liked both the "minstrel" and the "ahithophel," and, indeed, could hardly say, unlike as they were in complexion and character, which of the two i read oftenest or admired most. again, among the prose writers, addison was his especial favourite, and swift he detested; whereas i liked addison and swift almost equally well, and passed without sense of incongruity, from the vision of mirza, or the paper on westminster abbey, to the true account of the death of partridge, or the tale of a tub. if, however, he could wonder at the latitudinarian laxity of my taste, there was at least one special department in which i could marvel quite as much at the incomprehensible breadth of his. nature had given me, in despite of the phrenologists, who find music indicated by two large protuberances on the corners of my forehead, a deplorably defective ear. my uncle sandy, who was profoundly skilled in psalmody, had done his best to make a singer of me; but he was at length content to stop short, after a world of effort, when he had, as he thought, brought me to distinguish st. george's from any other psalm-tune. on the introduction, however, of a second tune into the parish church that repeated the line at the end of the stanza, even this poor fragment of ability deserted me; and to this day--though i rather like the strains of the bagpipe in general, and have no objection to drums in particular--doubts do occasionally come across me whether there be in reality any such thing as tune. my friend william ross was, on the contrary, a born musician. when a little boy, he had constructed for himself a fife and clarionet of young shoots of elder, on which he succeeded in discoursing sweet music; and addressing himself at another and later period to both the principles and practice of the science, he became one of the best flute-players in the district. notwithstanding my dulness of ear, i do cherish a pleasing recollection of the sweet sounds that used to issue from his little room in the outhouse, every milder evening as i approached, and of the soothed and tranquil state in which i ever found him on these occasions as i entered. i could not understand his music, but i saw that, mentally at least, though, i fear, not physically--for the respiratory organs were weak--it did him great good. there was, however, one special province in which our tastes thoroughly harmonized. we were both of us, if not alike favoured, at least equally devoted, lovers of the wild and beautiful in nature; and many a moonlight walk did we take together this winter among the woods and rocks of the hill. it was once said of thomson, by one who was himself not at all morbidly poetic in his feelings, that "he could not have viewed two candles burning but with a poetical eye." it might at least be said of my friend, that he never saw a piece of fine or striking scenery without being deeply moved by it. as for the mere candles, if placed on a deal dresser or shop-counter, they might have failed to touch him; but if burning in some _lyke_-wake beside the dead, or in some vaulted crypt or lonely rock-cave, he also could not have looked other than poetically on them. i have seen him awed into deep solemnity, in our walks, by the rising moon, as it peered down upon us over the hill, red and broad, and cloud-encircled, through the interstices of some clump of dark firs; and have observed him become suddenly silent, as, emerging from the moonlight woods, we looked into a rugged dell, and saw far beneath, the slim rippling streamlet gleaming in the light, like a narrow strip of the aurora borealis shot athwart a dark sky, when the steep rough sides of the ravine, on either hand, were enveloped in gloom. my friend's opportunities of general reading had not been equal to my own, but he was acquainted with at least one class of books of which i knew scarce anything;--he had carefully studied hogarth's "analysis of beauty," fresnoy's "art of painting," gessner's "letters," the "lectures of sir joshua reynolds," and several other works of a similar kind; and in all the questions of criticism that related to external form, the effects of light and shade, and the influences of the meteoric media, i found him a high authority. he had a fine eye for detecting the peculiar features which gave individuality and character to a landscape--those features, as he used to say, which the artist or poet should seize and render prominent, while, at the same time, lest they should be lost as in a mob, he softened down the others; and, recognising him as a master in this department of characteristic selection, i delighted to learn in his school--by far the best of its kind i ever attended. i was able, however, in part to repay him, by introducing him to many an interesting spot among the rocks, or to retired dells and hollows in the woods, which, from his sedentary habits, he would scarce ever have discovered for himself. i taught him too, to light fires after nightfall in the caves, that we might watch the effects of the strong lights and deep shadows in scenes so wild; and i still vividly remember the delight he experienced, when, after kindling up in the day-time a strong blaze at the mouth of the doocot cave, which filled the recess within with smoke, we forced our way inwards through the cloud, to mark the appearance of the sea and the opposite land seen through a medium so dense, and saw, on turning round, the landscape strangely enwrapped "in the dun hues of earthquake and eclipse." we have visited, after nightfall, the glades of the surrounding woods together, to listen to the night breeze, as it swept sullenly along the pine-tops; and, after striking a light in the old burial vault of a solitary churchyard, we have watched the ray falling on the fissured walls and ropy damp and mould; or, on setting on fire a few withered leaves, have seen the smoke curling slowly upwards, through a square opening in the roof, into the dark sky. william's mind was not of the scientific cast. he had, however, acquired some knowledge of the mathematics, and some skill both in architecture and in the anatomy of the human skeleton and muscles; while of perspective he perhaps knew well-nigh as much as was known at the time. i remember he preferred the treatise on this art, of ferguson the astronomer and mechanician, to any other; and used to say that the twenty years spent by the philosopher as a painter were fully redeemed, though they had produced no good pictures, by his little work on perspective alone. my friend had ere this time given up the writing of verses very much, because he had learned to know what verses ought to be, and failed to satisfy himself with his own; and ere his death, i saw him resign in succession his flute and pencil, and yield up all the hopes he had once cherished of being known. but his weak health affected his spirits, and prostrated the energies of a mind originally rather delicate than strong. chapter ix. "others apart sat on a hill retired, in thoughts more elevate; and reasoned high of providence, foreknowledge, will, and fate-- fixed fate, freewill, foreknowledge absolute; and found no end, in wandering mazes lost."--milton. spring came on, and brought with it its round of labour--quarrying, building, and stone-cutting; but labour had now no terrors for me: i wrought hard during the hours allotted to toil, and was content; and read, wrote, or walked, during the hours that were properly my own, and was happy. early in may, however, we had finished all the work for which my master had previously contracted; and as trade was unusually dull at the time, he could procure no further contracts, and the squad was thrown out of employment. i rushed to the woods and rocks, and got on with my lessons in geology and natural science; but my master, who had no lessons to learn, wearied sadly of doing nothing; and at length, very unwillingly--for he had enacted the part of the employer, though on a small scale, for a full quarter of a century--he set himself to procure work as a journeyman. he had another apprentice at the time; and he, availing himself of the opportunity which the old man's inability of employing him furnished, quitted his service, and commenced work on his own behalf--a step to which, though the position of a journeyman's apprentice seemed rather an anomalous one, i could not see my way. and so, as work turned up for both master and apprentice at a place about twenty miles distant from cromarty, i set out with him, to make trial, for the first time, of the sort of life that is spent in bothies and barracks. our work was to consist, i was informed, of building and hewing at an extensive farm-steading on the banks of the river conon, which one of the wealthier proprietors of the district was getting built for himself, not on contract, but by the old mode of employing operatives on day's wages; and my master was to be permitted to rate as a full journeyman, though now considerably in his decline as a workman, on condition that the services of his apprentice should be rated so much lower than their actual value as to render master and man regarded as one lot--a fair bargain to the employer, and somewhat more. the arrangement was not quite a flattering one for me; but i acquiesced in it without remark, and set out with my master for conon-side. the evening sun was gleaming delightfully as we neared the scene of our labours, on the broad reaches of the conon, and lighting up the fine woods and noble hills beyond. it would, i knew, be happiness to toil for some ten hours or so per day in so sweet a district, and then to find the evening all my own; but on reaching the work, we were told that we would require to set out in the morning for a place about four miles further to the west, where there were a few workmen engaged in building a jointure-house for the lady of a ross-shire proprietor lately dead, and which lay off the river in a rather unpromising direction. and so, a little after sun-rise, we had to take the road with our tools slung across our backs, and before six o'clock we reached the rising jointure-house, and set to work. the country around was somewhat bare and dreary--a scene of bogs and moors, overlooked by a range of tame heathy hills; but in our immediate neighbourhood there was a picturesque little scene--rather a vignette than a picture--that in some degree redeemed the general deformity. two meal-mills--the one small and old, the other larger and more modern--were placed beside each other, on ground so unequal, that, seen in front, the smaller seemed perched on the top of the larger; a group of tall graceful larches rose immediately beside the lower building, and hung their slim branches over the huge wheel; while a few aged ash-trees that encircled the mill-pond, which, in sending its waters down the hill, supplied both wheels in succession, sprang up immediately beside the upper erection, and shot their branches over its roof. on closing our labours for the evening, we repaired to the old mansion-house, about half a mile away, in which the dowager lady for whom we wrought still continued to reside, and where we expected to be accommodated, like the other workmen, with beds for the night. we had not been expected, however, and there were no beds provided for us; but as the highland carpenter who had engaged to execute the woodwork of the new building had an entire bed to himself, we were told we might, if we pleased, lie three a-bed with him. but though the carpenter was, i daresay, a most respectable man, and a thorough celt, i had observed during the day that he was miserably affected by a certain skin disease, which, as it was more prevalent in the past of highland history than even at this time, must have rendered his ancestors of old very formidable, even without their broadswords; and so i determined on no account to sleep with him. i gave my master fair warning, by telling him what i had seen; but uncle david, always insensible to danger, conducted himself on the occasion as in the sinking boat or under the falling bank, and so went to bed with the carpenter; while i, stealing out, got into the upper story of an out-house; and, flinging myself down in my clothes on the floor, on a heap of straw, was soon fast asleep. i was, however, not much accustomed at the time to so rough a bed: every time i turned me in my lair, the strong, stiff straw rustled against my face; and about midnight i awoke. i rose to a little window which opened upon a dreary moor, and commanded a view in the distance, of a ruinous chapel and solitary burying-ground, famous in the traditions of the district as the chapel and burying-ground of gillie-christ. dr. johnson relates, in his "journey," that when eating, on one occasion, his dinner in skye to the music of the bagpipe, he was informed by a gentleman, "that in some remote time, the macdonalds of glengarry having been injured or offended by the inhabitants of culloden, and resolving to have justice, or vengeance, they came to culloden on a sunday, when, finding their enemies at worship, they shut them up in the church, which they set on fire; and this, said he, is the tune that the piper played while they were burning." culloden, however, was not the scene of the atrocity: it was the mackenzies of ord that their fellow-christians and brother-churchmen, the macdonalds of glengarry, succeeded in converting into animal charcoal, when the poor people were engaged, like good catholics, in attending mass; and in this old chapel of gillie-christ was the experiment performed. the macdonalds, after setting fire to the building, held fast the doors until the last of the mackenzies of ord had perished in the flames; and then, pursued by the mackenzies of brahan, they fled into their own country, to glory ever after in the greatness of the feat. the evening was calm and still, but dark for the season, for it was now near mid-summer; and every object had disappeared in the gloom, save the outlines of a ridge of low hills that rose beyond the moor; but i could determine where the chapel and churchyard lay; and great was my astonishment to see a light flickering amid the grave-stones and the ruins. at one time seen, at another hid, like the revolving lantern of a lighthouse, it seemed to be passing round and round the building; and, as i listened, i could hear distinctly what appeared to be a continuous screaming of most unearthly sound, proceeding from evidently the same spot as the twinkle of the light. what could be the meaning of such an apparition, with such accompaniments--the time of its appearance midnight--the place a solitary burying-ground? i was in the highlands: was there truth, after all, in the many floating highland stories of spectral dead-lights and wild supernatural sounds, seen and heard by nights in lonely places of sepulture, when some sudden death was near? i did feel my blood run somewhat cold, for i had not yet passed the credulous time of life--and had some thoughts of stealing down to my master's bedside, to be within reach of the human voice, when i saw the light quitting the churchyard, and coming downwards across the moor in a straight line, though tossed about in the dead calm, in many a wave and flourish; and further, i could ascertain, that what i had deemed a persistent screaming was in reality a continuous singing, carried on at the pitch of a powerful though somewhat cracked voice. in a moment after, one of the servant girls of the mansion-house came rushing out half-dressed to the door of an outer-building in which the workmen and the farm-servant lay, and summoned them immediately to rise. mad bell had again broke out, she said, and would set them on fire a second time. the men rose, and, as they appeared at the door, i joined them; but on striking out a few yards into the moor, we found the maniac already in the custody of two men, who had seized and were dragging her towards her cottage, a miserable hovel, about half a mile away. she never once spoke to us, but continued singing, though in a lower and more subdued tone of voice than before, a gaelic song. we reached her hut, and, making use of her own light, we entered. a chain of considerable length, attached by a stopple in one of the highland _couples_ of the erection, showed that her neighbours had been compelled on former occasions to abridge her liberty; and one of the men, in now making use of it, so wound it round her person as to bind her down, instead of giving her the scope of the apartment, to the damp uneven floor. a very damp and uneven floor it was. there were crevices in the roof above, which gave free access to the elements; and the turf walls, perilously bulged by the leakage in several places, were green with mould. one of the masons and i simultaneously interfered. it would never do, we said, to pin down a human creature in that way to the damp earth. why not give her what the length of the chain permitted--the full range of the room? if we did that, replied the man, she would be sure to set herself free before morning, and we would just have to rise and bind her again. but we resolved, we rejoined, whatever might happen, that she should _not_ be tied down in that way to the filthy floor; and ultimately we succeeded in carrying our point. the song ceased for a moment: the maniac turned round, presenting full to the light the strongly-marked, energetic features of a woman of about fifty-five; and, surveying us with a keen, scrutinizing glance, altogether unlike that of the idiot, she emphatically repeated the sacred text, "blessed are the merciful, for they shall obtain mercy." she then began singing, in a low, mournful tone, an old scotch ballad; and, as we left the cottage, we could hear her voice gradually heightening as we retired, until it had at length attained to its former pitch and wildness of tone. before daybreak the maniac succeeded in setting herself free; but the paroxysm of the fit had meanwhile passed over; and when she visited me next morning at the place where i was hewing--a little apart from the other workmen, who were all engaged in building on the walls--save for the strongly-marked features, i would scarce have recognised her. she was neatly dressed, though her gown was neither fine nor new; her clean white cap was nicely arranged; and her air seemed to be rather that of the respectable tradesman's wife or daughter, than of the ordinary country woman. for some little time she stood beside me without speaking, and then somewhat abruptly asked,--"what makes _you_ work as a mason?" i made some commonplace reply; but it failed to satisfy her. "all your fellows are real masons," she said; "but you are merely in the disguise of a mason; and i have come to consult you about the deep matters of the soul." the matters she had come to inquire regarding were really very deep indeed; she had, i found, carefully read flavel's "treatise on the soul of man"--a volume which, fortunately for my credit, i also had perused; and we were soon deep together in the rather bad metaphysics promulgated on the subject by the schoolmen, and republished by the divine. it seemed clear, she said, that every human soul was created--not transmitted--created, mayhap, at the time when it began to be; but if so, how, or on what principle did it come under the influence of the fall? i merely remarked, in reply, that she was of course acquainted with the views of the old theologians--_such as flavel_--men who really knew as much about such things as could be known, and perhaps a little more: was she not satisfied with them? not dissatisfied, she said; but she wanted more light. could a soul not derived from our first parents be rendered vile simply by being put into a body derived from them? one of the passages in flavel, on this special point, had luckily struck me, from its odd obscurity of expression, and i was able to quote it in nearly the original words. you know, i remarked, that a great authority on the question "declined confidently to affirm that the moral infection came by way of physical agency, as a rusty scabbard infects and defiles a bright sword when sheathed therein: it might be," he thought, "by way of natural concomitancy, as estius will have it; or, to speak as dr. reynolds doth, by way of ineffable resultancy and emanation." as this was perfectly unintelligible, it seemed to satisfy my new friend. i added, however, that, like herself, i was waiting for more light on the difficulty, and might set myself to it in right earnest, when i found it fully demonstrated that the creator could not, or did not, make man equally the descendant in soul as in body of the original progenitors of the race. i believed, with the great mr. locke, that he could do it; nor was i aware he had anywhere said that what he could do in the matter he had not done. such was the first of many strange conversations with the maniac, who, with all her sad brokenness of mind, was one of the most intellectual women i ever knew. humble as were the circumstances in which i found her, her brother, who was at this time about two years dead, had been one of the best-known ministers of the scottish church in the northern highlands. to quote from an affectionate notice by the editor of a little volume of his sermons, published a few years ago--the rev. mr. mackenzie of north leith--"he was a profound divine, an eloquent preacher, a deeply-experienced christian, and, withal, a classical scholar, a popular poet, a man of original genius, and eminently a man of prayer." and his poor sister isabel, though grievously vexed at times by a dire insanity, seemed to have received from nature powers mayhap not inferior to his. we were not always engaged with the old divines; isabel's tenacious memory was stored with the traditions of the district; and many an anecdote could she tell of old chieftains, forgotten on the lands which had once been their own, and of highland poets, whose songs had been sung for the last time. the story of the "raid of gillie-christ" has been repeatedly in print since i first heard it from her: it forms the basis of the late sir thomas dick lander's powerful tale of "allan with the red jacket;" and i have seen it in its more ordinary traditionary dress, in the columns of the _inverness courier_. but at this time it was new to me; and on no occasion could it have lost less by the narrator. she was herself a mackenzie; and her eyes flashed a wild fire when she spoke of the barbarous and brutal macdonalds, and of the measured march and unfaltering notes of their piper outside the burning chapel, when her perishing ancestors were shrieking in their agony within. she was acquainted also with the resembling story of that cave of eigg, in which a body of the macdonalds themselves, consisting of men, women, and children--the entire population of the island--had been suffocated wholesale by the macleods of skye; and i have heard from her more good sense on the subject of the highland character "ere the gospel changed it," as illustrated by these passages in their history, than from some highlanders sane enough on other matters, but carried away by a too indiscriminating respect for the wild courage and half-instinctive fidelity of the old race. the ancient highlanders were bold, faithful dogs, she has said, ready to die for their masters, and prepared to do, at their bidding, like other dogs, the most cruel and wicked actions; and as dogs often were they treated; nay, even still, after religion had made them men (as if condemned to suffer for the sins of their parents), they were frequently treated as dogs. the pious martyrs of the south had contended in god's behalf; whereas the poor highlanders of the north had but contended in behalf of their chiefs; and so, while god had been kind to the descendants of _his_ servants, the chiefs had been very unkind to the descendants of theirs. from excellent sense, however, in these conversations, my new companion used often to wander into deplorable insanity. her midnight visits to the old chapel of gillie-christ were made, she said, in order that she might consult her father in her difficulties; and the good man, though often silent for nights together, rarely failed to soothe and counsel her from the depths of his quiet grave, on every occasion when her unhappiness became extreme. it was acting on his advice, however, that she had set fire to a door that had for a time excluded her from the burying-ground, and burnt it down. she had been married in early life; and i have rarely heard anything wilder or more ingenious than the account she gave of a quarrel with her husband, that terminated in their separation. after living happily with him for several years, she all at once, she said, became most miserable, and everything in their household went on ill. but though her husband seemed to have no true conception of the cause of their new-born misery, she had. he used, from motives of economy, to keep a pig, which, when converted into bacon, was always useful in the family; and an occasional ham of the animal now and then found its way to her brother's manse, as a sort of friendly acknowledgment of the many good things received from him. one wretched pig, however--a little black thing, only a few weeks old--which her husband had purchased at a fair, was, she soon discovered, possessed by an evil spirit, that had a strange power of quitting the animal to do mischief in her dwelling, and an ability of not only rendering her fearfully unhappy, but even of getting at times into her husband. the husband himself, poor blinded man! could see nothing of all this; nor would he believe _her_, who could and did see it; nor yet could she convince him that it was decidedly his duty to get rid of the pig. she was not satisfied that she herself had a clear right to kill the creature: it was undoubtedly her husband's property, not hers; but could she only succeed in placing it in circumstances in which it might be free either to kill itself or not, and were it, in these circumstances, to destroy itself, she was sure all the better divines would acquit her of aught approaching to moral guilt in the transaction; and the relieved household would be free from both the evil spirit and the little pig. the mill-pond was situated immediately beside her dwelling: its steep sides, which were walled with stone, were unscaleable by at least little pigs; and among the aged ashes which sprang up immediately at its edge, there was one that shot out a huge bough, like a bent arm, directly over it, far beyond the stonework, so that the boys of the neighbourhood used to take their seat on it, and fish for little trout that sometimes found their way into the pond. on the projecting branch one day, when her husband's back was turned, and there was no one to see or interfere, she placed the pig. it stood for a while: there was no doubt, therefore, it _could_ stand; but, unwilling to stand any longer, it sprawled--slipped--fell--dropped into the water, in short--and ultimately, as it could not make its way up the bank, was drowned. and thus ended the pig. it would seem, however, as if the evil spirit had got into her husband instead--so extreme was his indignation at the transaction. he would accept of neither apology nor explanation; and, unable of course to live any longer under the same roof with a man so unreasonable, she took the opportunity, when he was quitting that part of the country for employment at a distance, to remain behind in her old cottage--the same in which she at that time resided. such was the maniac's account of her quarrel with her husband; and, when listening to men chopping little familiar logic on one of the profoundest mysteries of revelation--a mystery which, once received as an article of faith, serves to unlock many a difficulty, but which is itself wholly irreducible by the human intellect--i have been sometimes involuntarily led to think of her ingenious but not very sound argumentation on the fall of the pig. it is dangerous to attempt explaining, in the theological province, what in reality cannot be explained. some weak abortion of the human reason is always substituted, in the attempt, for some profound mystery in the moral government of god; and men ill-grounded in the faith are led to confound the palpable abortion with the inscrutable mystery, and are injured in consequence. i succeeded in getting a bed in the mansion-house, without, like marsyas of old, perilling my skin; and though there was but little of interest in the immediate neighbourhood, and not much to be enjoyed within doors--for i could procure neither books nor congenial companionship--with the assistance of my pencil and sketch-book i got over my leisure hours tolerably well. my new friend isabel would have given me as much of her conversation as i liked; for there was many a point on which she had to consult me, and many a mystery to state, and secret to communicate; but, though always interested in her company, i was also always pained, and invariably quitted her, after each lengthened _tête-à-tête_, in a state of low spirits, which i found it difficult to shake off. there seems to be something peculiarly unwholesome in the society of a strong-minded maniac; and so i contrived as much as possible--not a little, at times, to her mortification--to avoid her. for hours together, however, i have seen her perfectly sane; and, on these occasions, she used to speak much about her brother, for whom she entertained a high reverence, and gave me many anecdotes regarding him, not uninteresting in themselves, which she told remarkably well. some of these my memory still retains. "there were two classes of men," she has said, "for whom he had a special regard--christian men of consistent character; and men who, though they made no profession of religion, were honest in their dealings, and of kindly dispositions. and with people of this latter kind he used to have a great deal of kindly intercourse, cheerful enough at times--for he could both make a joke and take one--but which usually did his friends good in the end. so long as my father and my mother lived, he used to travel across the country once every year to pay them a visit; and he was accompanied, on one of these journeys, by one of this less religious class of his parishioners, who had, however, a great regard for him, and whom he liked, in turn, for his blunt honesty, and obliging disposition. they had baited for some time at a house in the outer skirts of my brother's parish, where there was a child to baptize, and where, i fear, donald must have got an extra dram; for he was very argumentative all the evening after; and finding he could not agree with my brother on any one subject, he suffered him to shoot a-head for a few hundred yards, and did not again come up with him, until, in passing through a thick clump of natural wood, he found him standing, lost in thought, before a singularly-shaped tree. donald had never seen such a strange-looking tree in all his days before. the lower part of it was twisted in and out, and backwards and forwards, like an ill-made cork-screw; while the higher shot straight upwards, direct as a line; and its taper top seemed like a finger pointing at the sky. 'come, tell me, donald,' said my brother, 'what you think this tree is like?' 'indeed, i kenna, mr. lachlan,' replied donald; 'but if you let me take that straight bit aff the tap o't, it will be gey an' like the _worm_ o' a whisky still.' 'but i cannot want the straight bit,' said my brother; 'the very pith and point of my comparison lies in the straight bit. one of the old fathers would perhaps have said, donald, that that tree resembled the course of the christian. his early progress has turns and twists in it, just like the lower part of that tree; one temptation draws him to the left--another to the right: his upward course is a crooked one; but it is an upward course for all that; for he has, like the tree, the principle of sky-directed growth within him: the disturbing influences weaken as grace strengthens, and appetite and passion decay; and so the early part of his career is not more like the warped and twisted trunk of that tree, than his latter years resemble its taper top. he shoots off heavenward in a straight line.'" such is a specimen of the anecdotes of this poor woman. i saw her once afterwards, though for only a short time; when she told me that, though people could not understand _us_, there was meaning in both her thoughts and in mine; and some years subsequently, when i was engaged as a journeyman mason in the south of scotland, she walked twenty miles to pay my mother a visit, and stayed with her for several days. her death was a melancholy one. when fording the river conon in one of her wilder moods, she was swept away by the stream and drowned, and her body cast upon the bank a day or two after. our work finished at this place, my master and i returned on a saturday evening to conon-side, where we found twenty-four workmen crowded in a rusty corn-kiln, open from gable to gable, and not above thirty feet in length. a row of rude beds, formed of undressed slabs, ran along the sides; and against one of the gables there blazed a line of fires, with what are known as masons' setting-irons, stuck into the stonework behind, for suspending over them the pots used in cooking the food of the squad. the scene, as we entered, was one of wild confusion. a few of the soberer workmen were engaged in "baking and firing" oaten cakes, and a few more occupied, with equal sobriety, in cooking their evening porridge; but in front of the building there was a wild party of apprentices, who were riotously endeavouring to prevent a highland shepherd from driving his flock past them, by shaking their aprons at the affrighted animals; and a party equally bent on amusement inside were joining with burlesque vehemence in a song which one of the men, justly proud of his musical talents, had just struck up. suddenly the song ceased, and with wild uproar a bevy of some eight or ten workmen burst out into the green in full pursuit of a squat little fellow, who had, they said, insulted the singer. the cry rose wild and high, "a ramming! a ramming!" the little fellow was seized and thrown down; and five men--one holding his head, and one stationed at each arm and leg--proceeded to execute on his body the stern behests of barrack-law. he was poised like an ancient battering-ram, and driven endlong against the wall of the kiln,--that important part of his person coming in violent contact with the masonry, "where," according to butler, "a kick hurts honour" very much. after the third blow, however, he was released, and the interrupted song went on as before. i was astonished, and somewhat dismayed, by this specimen of barrack-life; but, getting quietly inside the building, i succeeded in cooking for my uncle and myself some porridge over one of the unoccupied fires, and then stole off, as early as i could, to my lair in a solitary hay-loft--for there was no room for us in the barrack--where, by the judicious use of a little sulphur and mercury, i succeeded in freeing my master from the effects of the strange bed-fellowship which our recent misery had made, and preserving myself from infection. the following sabbath was a day of quiet rest; and i commenced the labours of the week, disposed to think that my lot, though rather a rough one, was not altogether unendurable; and that, even were it worse than it was, it would be at once wise and manly, seeing that winter would certainly come, cheerfully to acquiesce in and bear up under it. i had, in truth, entered a school altogether new--at times, as i have just shown, a singularly noisy and uproarious one, for it was a school without master or monitor; but its occasional lessons were, notwithstanding, eminently worthy of being scanned. all know that there exists such a thing as professional character. on some men, indeed, nature imprints so strongly the stamp of individuality, that the feebler stamp of circumstance and position fails to impress them. such cases, however, must always be regarded as exceptional. on the average masses of mankind, the special employments which they pursue, or the kinds of business which they transact, have the effect of moulding them into distinct classes, each of which bears an artificially induced character peculiarly its own. clergymen, as such, differ from merchants and soldiers, and all three from lawyers and physicians. each of these professions has long borne in our literature, and in common opinion, a character so clearly appreciable by the public generally, that, when truthfully reproduced in some new work of fiction, or exemplified by some transaction in real life, it is at once recognised as marked by the genuine class-traits and peculiarities. but the professional characteristics descend much lower in the scale than is usually supposed. there is scarce a trade or department of manual labour that does not induce its own set of peculiarities--peculiarities which, though less within the range of the observation of men in the habit of recording what they remark, are not less real than those of the man of physic or of law. the barber is as unlike the weaver, and the tailor as unlike both, as the farmer is unlike the soldier, or as either farmer or soldier is unlike the merchant, lawyer, or minister. and it is only on the same sort of principle that all men, when seen from the top of a lofty tower, whether they be tall or short, seem of the same stature, that these differences escape the notice of men in the higher walks. between the workmen that pass sedentary lives within doors, such as weavers and tailors, and those who labour in the open air, such as masons and ploughmen, there exists a grand generic difference. sedentary mechanics are usually less contented than laborious ones; and as they almost always work in parties, and as their comparatively light, though often long and wearily-plied employments, do not so much strain their respiratory organs but that they can keep up an interchange of idea when at their toils, they are generally much better able to state their grievances, and much more fluent in speculating on their causes. they develop more freely than the laborious out-of-door workers of the country, and present, as a class, a more intelligent aspect. on the other hand, when the open-air worker does so overcome his difficulties as to get fairly developed, he is usually of a fresher or more vigorous type than the sedentary one. burns, hogg, allan cunningham, are the literary representatives of the order; and it will be found that they stand considerably in advance of the thoms, bloomfields, and tannahills, that represent the sedentary workmen. the silent, solitary, hard-toiled men, if nature has put no better stuff in them than that of which stump-orators and chartist lecturers are made, remain silent, repressed by their circumstances; but if of a higher grade, and if they once do get their mouths fairly opened, they speak with power, and bear with them into our literature the freshness of the green earth and the freedom of the open sky. the specific peculiarities induced by particular professions are not less marked than the generic ones. how different, for instance, the character of a sedentary tailor, as such, from that of the equally sedentary barber! two imperfectly-taught young lads, of not more than the average intellect, are apprenticed, the one to the hair-dresser, the other to the fashionable clothes-maker of a large village. the barber has to entertain his familiar round of customers, when operating upon their heads and beards. he must have no controversies with them; that might be disagreeable, and might affect his command of the scissors or razor; but he is expected to communicate to them all he knows of the gossip of the place; and as each customer supplies him with a little, he of course comes to know more than anybody else. and as his light and easy work lays no stress on his respiration, in course of time he learns to be a fast and fluent talker, with a great appetite for news, but little given to dispute. he acquires, too, if his round of customers be good, a courteous manner; and if they be in large proportion conservatives, he becomes, in all probability, a conservative too. the young tailor goes through an entirely different process. he learns to regard dress as the most important of all earthly things--becomes knowing in cuts and fashions--is taught to appreciate, in a way no other individual can, the aspect of a button, or the pattern of a vest; and as his work is cleanly, and does not soil his clothes, and as he can get them more cheaply, and more perfectly in the fashion, than other mechanics, the chances are ten to one that he turns out a beau. he becomes great in that which he regards as of all things greatest--dress. a young tailor may be known by the cut of his coat and the merits of his pantaloons, among all other workmen; and as even fine clothes are not enough of themselves, it is necessary that he should also have fine manners; and not having such advantages of seeing polite society as his neighbour the barber, his gentlemanly manners are always less fine than grotesque. hence more ridicule of tailors among working men than of any other class of mechanics. and such--if nature has sent them from her hand ordinary men, for the extraordinary rise above all the modifying influences of profession--are the processes through which tailors and hair-dressers put on then distinctive characters as such. a village smith hears well-nigh as much gossip as a village barber; but he develops into an entirely different sort of man. he is not bound to please his customers by his talk; nor does his profession leave his breath free enough to talk fluently or much; and so he listens in grim and swarthy independence--strikes his iron while it is hot--and when, after thrusting it into the fire, he bends himself to the bellows, he drops, in rude phrase, a brief judicial remark, and again falls sturdily to work. again, the shoemaker may be deemed, in the merely mechanical character of his profession, near of kin to the tailor. but such is not the case. he has to work amid paste, wax, oil, and blacking, and contracts a smell of leather. he cannot keep himself particularly clean; and although a nicely-finished shoe be all well enough in its way, there is not much about it on which conceit can build. no man can set up as a beau on the strength of a prettily-shaped shoe; and so a beau the shoemaker is not, but, on the contrary, a careless, manly fellow, who, when not overmuch devoted to saint monday, gains usually, in his course through life, a considerable amount of sense. shoemakers are often in large proportions intelligent men; and bloomfield, the poet, gifford the critic and satirist, and carey the missionary, must certainly be regarded as thoroughly respectable contributions from the profession, to the worlds of poetry, criticism, and religion. the professional character of the mason varies a good deal in the several provinces of scotland, according to the various circumstances in which he is placed. he is in general a blunt, manly, taciturn fellow, who, without much of the radical or chartist about him, especially if wages be good and employment abundant, rarely touches his hat to a gentleman. his employment is less purely mechanical than many others: he is not like a man ceaselessly engaged in pointing needles or fashioning pin-heads. on the contrary, every stone he lays or hews demands the exercise of a certain amount of judgment for itself; and so he cannot wholly suffer his mind to fall asleep over his work. when engaged, too, in erecting some fine building, he always experiences a degree of interest in marking the effect of the design developing itself piecemeal, and growing up under his hands; and so he rarely wearies of what he is doing. further, his profession has this advantage, that it educates his sense of sight. accustomed to ascertain the straightness of lines at a glance, and to cast his eye along plane walls, or the mouldings of entablatures or architraves, in order to determine the rectitude of the masonry, he acquires a sort of mathematical precision in determining the true bearings and position of objects, and is usually found, when admitted into a rifle club, to equal, without previous practice, its second-rate shots. he only falls short of its first-rate ones, because, uninitiated by the experience of his profession in the mystery of the parabolic curve, he fails, in taking aim, to make the proper allowance for it. the mason is almost always a silent man: the strain on his respiration is too great, when he is actively employed, to leave the necessary freedom to the organs of speech; and so at least the provincial builder or stone-cutter rarely or never becomes a democratic orator. i have met with exceptional cases in the larger towns; but they were the result of individual idiosyncrasies, developed in clubs and taverns, and were not professional. it is, however, with the character of our north-country masons that i have at present chiefly to do. living in small villages, or in cottages in the country, they can very rarely procure employment in the neighbourhood of their dwellings, and so they are usually content to regard these as simply their homes for the winter and earlier spring months, when they have nothing to do, and to remove for work to other parts of the country, where bridges, or harbours, or farm-steadings are in the course of building--to be subjected there to the influences of what is known as the barrack, or rather bothy life. these barracks or bothies are almost always of the most miserable description. i have lived in hovels that were invariably flooded in wet weather by the overflowings of neighbouring swamps, and through whose roofs i could tell the hour at night, by marking from my bed the stars that were passing over the openings along the ridge: i have resided in other dwellings of rather higher pretensions, in which i have been awakened during every heavier night-shower by the rain-drops splashing upon my face where i lay a-bed. i remember that uncle james, in urging me not to become a mason, told me that a neighbouring laird, when asked why he left a crazy old building standing behind a group of neat modern offices, informed the querist that it was not altogether through bad taste the hovel was spared, but from the circumstance that he found it of great convenience every time his speculations brought a _drove of pigs_ or _a squad of masons_ the way. and my after experience showed me that the story might not be in the least apocryphal, and that masons had reason at times for not touching their hats to gentlemen. in these barracks the food is of the plainest and coarsest description: oatmeal forms its staple, with milk, when milk can be had, which is not always; and as the men have to cook by turns, with only half an hour or so given them in which to light a fire, and prepare the meal for a dozen or twenty associates, the cooking is invariably an exceedingly rough and simple affair. i have known mason-parties engaged in the central highlands in building bridges, not unfrequently reduced, by a tract of wet weather, that soaked their only fuel the turf, and rendered it incombustible, to the extremity of eating their oatmeal raw, and merely moistened by a little water, scooped by the hand from a neighbouring brook. i have oftener than once seen our own supply of salt fail us; and after relief had been afforded by a highland smuggler--for there was much smuggling in salt in those days, ere the repeal of the duties--i have heard a complaint from a young fellow regarding the hardness of our fare, at once checked by a comrade's asking him whether he was not an ungrateful dog to grumble in that way, seeing that, after living on fresh poultices for a week, we had actually that morning got porridge with salt in it. one marked effect of the annual change which the north-country mason has to undergo, from a life of domestic comfort to a life of hardship in the bothy, if he has not passed middle life, is a great apparent increase in his animal spirits. at home he is in all probability a quiet, rather dull-looking personage, not much given to laugh or joke; whereas in the bothy, if the squad be a large one, he becomes wild, and a humorist--laughs much, and grows ingenious in playing off pranks on his fellows. as in all other communities, there are certain laws recognised in the barrack as useful for controlling at least its younger members, the apprentices; but in the general tone of merriment, even these lose their character, and, ceasing to be a terror to evildoers, become in the execution mere occasions of mirth. i never, in all my experience, saw a serious punishment inflicted. shortly after our arrival at conon-side, my master, chancing to remark that he had not wrought as a journeyman for twenty-five years before, was voted a "ramming," for taking, as was said, such high ground with his brother workmen; but, though sentence was immediately executed, they dealt gently with the old man, who had good sense enough to acquiesce in the whole as a joke. and yet, amid all this wild merriment and license, there was not a workman who did not regret the comforts of his quiet home, and long for the happiness which was, he felt, to be enjoyed only there. it has been long known that gaiety is not solid enjoyment; but that the gaiety should indicate little else than the want of solid enjoyment, is a circumstance not always suspected. my experience of barrack-life has enabled me to receive without hesitation what has been said of the occasional merriment of slaves in america and elsewhere, and fully to credit the often-repeated statement, that the abject serfs of despotic governments laugh more than the subjects of a free country. poor fellows! if the british people were as unhappy as slaves or serfs, they would, i daresay, learn in time to be quite as merry. there are, however, two circumstances that serve to prevent the bothy life of the north-country mason from essentially injuring his character in the way it almost never fails to injure that of the farm-servant. as he has to calculate on being part of every winter, and almost every spring, unemployed, he is compelled to practise a self-denying economy, the effect of which, when not carried to the extreme of a miserly narrowness, is always good; and hallow-day returns him every season to the humanizing influences of his home. chapter x. "the muse, nae poet ever fand her, till by himsel' he learned to wander adown some trottin' burn's meander, an' no think lang: oh, sweet to muse, and pensive ponder a heartfelt sang!"--burns. there are delightful walks in the immediate neighbourhood of conon-side; and as the workmen--engaged, as i have said, on day's wages--immediately ceased working as the hour of six arrived, i had, during the summer months, from three to four hours to myself every evening, in which to enjoy them. the great hollow occupied by the waters of the cromarty firth divides into two valleys at its upper end, just where the sea ceases to flow. there is the valley of the peffer, and the valley of the conon; and a tract of broken hills lies between, formed of the great conglomerate base of the old red system. the conglomerate, always a picturesque deposit, terminates some four or five miles higher up the valley, in a range of rough precipices, as bold and abrupt, though they front the interior of the country, as if they formed the terminal barrier of some exposed sea-coast. a few straggling pines crest their summits; and the noble woods of brahan castle, the ancient seat of the earls of seaforth, sweep downwards from their base to the margin of the conon. on our own side of the river, the more immature but fresh and thickly-clustered woods of conon house rose along the banks; and i was delighted to find among them a ruinous chapel and ancient burying-ground, occupying, in a profoundly solitary corner, a little green hillock, once an island of the river, but now left dry by the gradual wear of the channel, and the consequent fall of the water to a lower level. a few broken walls rose on the highest peak of the eminence; the slope was occupied by the little mossy hillocks and sorely lichened tombstones that mark the ancient grave-yard; and among the tombs immediately beside the ruin there stood a rustic dial, with its iron gnomon worn to an oxydized film, and green with weather-stains and moss. and around this little lonely yard sprang the young wood, thick as a hedge, but just open enough towards the west to admit, in slant lines along the tombstones and the ruins, the red light of the setting sun. i greatly enjoyed those evening walks. from conon-side as a centre, a radius of six miles commands many objects of interest; strathpeffer, with its mineral springs--castle leod, with its ancient trees, among the rest, one of the largest spanish chestnuts in scotland--knockferrel, with its vitrified fort--the old tower of fairburn--the old though somewhat modernized tower of kinkell--the brahan policies, with the old castle of the seaforths--the old castle of kilcoy--and the druidic circles of the moor of redcastle. in succession i visited them all, with many a sweet scene besides; but i found that my four hours, when the visit involved, as it sometimes did, twelve miles' walking, left me little enough time to examine and enjoy. a half-holiday every week would be a mighty boon to the working man who has acquired a taste for the quiet pleasures of intellect, and either cultivates an affection for natural objects, or, according to the antiquary, "loves to look upon what is old." my recollections of this rich tract of country, with its woods, and towers, and noble river, seem as if bathed in the red light of gorgeous sunsets. its uneven plain of old red sandstone leans, at a few miles' distance, against dark highland hills of schistose gneiss, that, at the line where they join on to the green lowlands, are low and tame, but sweep upwards into an alpine region, where the old scandinavian flora of the country--that flora which alone flourished in the times of its boulder clay--still maintains its place against the germanic invaders which cover the lower grounds, as the celt of old used to maintain exactly the same ground against the saxon. and at the top of a swelling moor, just beneath where the hills rise rugged and black, stands the pale tall tower of fairburn, that, seen in the gloamin', as i have often seen it, seems a ghastly spectre of the past, looking from out its solitude at the changes of the present. the freebooter, its founder, had at first built it, for greater security, without a door, and used to climb into it through the window of an upper story by a ladder. but now unbroken peace brooded over its shattered ivy-bound walls, and ploughed fields crept up year by year along the moory slope on which it stood, until at length all became green, and the dark heath disappeared. there is a poetic age in the life of most individuals, as certainly as in the history of most nations; and a very happy age it is. i had now fully entered on it; and enjoyed in my lonely walks along the conon, a happiness ample enough to compensate for many a long hour of toil, and many a privation. i have quoted, as the motto of this chapter, an exquisite verse from burns. there is scarce another stanza in the wide round of british literature that so faithfully describes the mood which, regularly as the evening came, and after i had buried myself in the thick woods, or reached some bosky recess of the river bank, used to come stealing over me, and in which i have felt my heart and intellect as thoroughly in keeping with the scene and hour as the still woodland pool beside me, whose surface reflected in the calm every tree and rock that rose around it, and every hue of the heavens above. and yet the mood, though sweet, was also, as the poet expresses it, a pensive one: it was steeped in the happy melancholy sung so truthfully by an elder bard, who also must have entered deeply into the feeling. "when i goe musing all alone, thinking of divers things foreknowne-- when i builde castles in the air, voide of sorrow and voide of care, pleasing myself with phantasms sweet-- methinks the time runs very fleet; all my joyes to this are follie;-- none soe sweet as melanchollie. "when to myself i sit and smile, with pleasing thoughts the time beguile, by a brook side or wood soe green, unheard, unsought for, or unseen, a thousand pleasures doe me blesse, and crowne my soul with happiness all my joyes to this are follie;-- none soe sweet as melanchollie." when i remember how my happiness was enhanced by every little bird that burst out into sudden song among the trees, and then as suddenly became silent, or by every bright-scaled fish that went darting through the topaz-coloured depths of the water, or rose for a moment over its calm surface--how the blue sheets of hyacinths that carpeted the openings in the wood delighted me, and every golden-tinted cloud that gleamed over the setting sun, and threw its bright flush on the river, seemed to inform the heart of a heaven beyond--i marvel, in looking over the scraps of verse produced at the time, to find how little of the sentiment in which i so luxuriated, or of the nature which i so enjoyed, found their way into them. but what wordsworth well terms "the accomplishment of verse," given to but few, is as distinct from the poetic faculty vouchsafed to many, as the ability of relishing exquisite music is distinct from the power of producing it. nay, there are cases in which the "faculty" may be very high, and yet the "accomplishment" comparatively low, or altogether wanting. i have been told by the late dr. chalmers, whose astronomical discourses form one of the finest philosophical poems in any language, that he never succeeded in achieving a readable stanza; and dr. thomas brown, whose metaphysics glow with poetry, might, though he produced whole volumes of verse, have said nearly the same thing of himself. but, like the metaphysician, who would scarce have published his verses unless he had thought them good ones, my rhymes pleased me at this period, and for some time after, wonderfully well: they came to be so associated in my mind with the scenery amid which they were composed, and the mood which it rarely failed of inducing, that though they neither breathed the mood nor reflected the scenery, they always suggested both; on the principle, i suppose, that a pewter spoon, bearing the london stamp, suggested to a crew of poor weather-beaten sailors in one of the islands of the pacific, their far-distant home and its enjoyments. one of the pieces suggested at this time i shall, however, venture on submitting to the reader. the few simple thoughts which it embodies arose in the solitary churchyard among the woods, beside the aged, lichen-incrusted dial-stone. on seeing a sun-dial in a churchyard grey dial-stone, i fain would know what motive placed thee here, where darkly opes the frequent grave, and rests the frequent bier. ah! bootless creeps the dusky shade, slow o'er thy figured plain: when mortal life has passed away, time counts his hours in vain. as sweeps the clouds o'er ocean's breast, when shrieks the wintry wind. so doubtful thoughts, grey dial-stone, come sweeping o'er my mind. i think of what could place thee here, of those beneath thee laid, and ponder if thou wert not raised in mockery o'er the dead. nay, man, when on life's stage they fret. may mock his fellow-men! in sooth, their soberest freaks afford rare food for mockery then. but ah! when passed their brief sojourn-- when heaven's dread doom is said-- beats there the human heart could pour like mockeries o'er the dead? the fiend unblest, who still to harm directs his felon power, may ope the book of grace to him whose day of grace is o'er; but never sure could mortal man, whate'er his age or clime, thus raise in mockery o'er the dead, the stone that measures time. grey dial-stone, i fain would know what motive placed thee here, where sadness heaves the frequent sigh, and drops the frequent tear. like thy carved plain, grey dial-stone, grief's weary mourners be: dark sorrow metes out time to them-- dark shade marks time on thee. i know it now: wert thou not placed to catch the eye of him to whom, through glistening tears, earth's gauds worthless appear, and dim? we think of time when time has fled, the friend our tears deplore; the god whom pride-swollen hearts deny, grief-humbled hearts adore. grey stone, o'er thee the lazy night passes untold away; nor were it thine at noon to teach if failed the solar ray. in death's dark night, grey dial-stone, cease all the works of men; in life, if heaven withhold its aid, bootless these works and vain. grey dial-stone, while yet thy shade points out those hours are mine-- while yet at early morn i rise-- and rest at day's decline-- would that the sun that formèd thine, his bright rays beamed on me, that i, wise for the final day, might measure time, like thee! these were happy evenings--all the more happy from the circumstance that i was still in heart and appetite a boy, and could relish as much as ever, when their season came on, the wild raspberries of the conon woods--a very abundant fruit in that part of the country--and climb as lightly as ever, to strip the guean-trees of their wild cherries. when the river was low, i used to wade into its fords in quest of its pearl muscles (_unio margaritiferus_); and, though not very successful in my pearl-fishing, it was at least something to see how thickly the individuals of this greatest of british fresh-water molluscs lay scattered among the pebbles of the fords, or to mark them creeping slowly along the bottom--when, in consequence of prolonged droughts, the current had so moderated that they were in no danger of being swept away--each on its large white foot, with its valves elevated over its back, like the carpace of some tall tortoise. i found occasion at this time to conclude, that the _unio_ of our river-fords secretes pearls so much more frequently than the _unionidæ_ and _anadonta_ of our still pools and lakes, not from any specific peculiarity in the constitution of the creature, but from the effects of the habitat which it is its nature to choose. it receives in the fords and shallows of a rapid river many a rough blow from sticks and pebbles carried down in times of flood, and occasionally from the feet of the men and animals that cross the stream during droughts; and the blows induce the morbid secretions of which pearls are the result. there seems to exist no inherent cause why _anadon cygnea_, with its beautiful silvery nacre--as bright often, and always more delicate than that of _unio margaritiferus_--should not be equally productive of pearls; but, secure from violence in its still pools and lakes, and unexposed to the circumstances that provoke abnormal secretions, it does not produce a single pearl for every hundred that are ripened into value and beauty by the exposed current-tossed _unionidæ_ of our rapid mountain rivers. would that hardship and suffering bore always in a creature of a greatly higher family similar results, and that the hard buffets dealt him by fortune in the rough stream of life could be transmuted, by some blessed internal predisposition of his nature, into pearls of great price. it formed one of my standing enjoyments at this time to bathe, as the sun was sinking behind the woods, in the deeper pools of the conon--a pleasure which, like all the more exciting pleasures of youth, bordered on terror. like that of the poet, when he "wantoned with the breakers," and the "freshening sea made them a terror," "'twas a pleasing fear." but it was not current nor freshening eddy that rendered it such: i had acquired, long before, a complete mastery over all my motions in the water, and, setting out from the shores of the bay of cromarty, have swam round vessels in the roadstead, when, among the many boys of a seaport town, not more than one or two would venture to accompany me; but the poetic age is ever a credulous one, as certainly in individuals as in nations: the old fears of the supernatural may be modified and etherealized, but they continue to influence it; and at this period the conon still took its place among the haunted streams of scotland. there was not a river in the highlands that used, ere the erection of the stately bridge in our neighbourhood, to sport more wantonly with human life--an evidence, the ethnographer might perhaps say, of its purely celtic origin; and as superstition has her figures as certainly as poesy, the perils of a wild mountain-born stream, flowing between thinly-inhabited banks, were personified in the beliefs of the people by a frightful goblin, that took a malignant delight in luring into its pools, or overpowering in its fords, the benighted traveller. its goblin, the "water-wraith," used to appear as a tall woman dressed in green, but distinguished chiefly by her withered, meagre countenance, ever distorted by a malignant scowl. i knew all the various fords--always dangerous ones--where of old she used to start, it was said, out of the river, before the terrified traveller, to point at him, as in derision, with her skinny finger, or to beckon him invitingly on; and i was shown the very tree to which a poor highlander had clung, when, in crossing the river by night, he was seized by the goblin, and from which, despite of his utmost exertions, though assisted by a young lad, his companion, he was dragged into the middle of the current, where he perished. and when, in swimming at sunset over some dark pool, where the eye failed to mark or the foot to sound the distant bottom, the twig of some sunken bush or tree has struck against me as i passed, i have felt, with sudden start, as if touched by the cold, bloodless fingers of the goblin. the old chapel among the woods formed the scene, says tradition, of an incident similar to that which sir walter scott relates in his "heart of mid-lothian," when borrowing, as the motto of the chapter in which he describes the preparations for the execution of porteous, from an author rarely quoted--the kelpie. "the hour's come," so runs the extract, "but not the man;"--nearly the same words which the same author employs in his "guy mannering," in the cave scene between meg merrilies and dirk hatteraick. "there is a tradition," he adds in the accompanying note, "that while a little stream was swollen into a torrent by recent showers, the discontented voice of the water-spirit was heard to pronounce these words. at the same moment, a man urged on by his fate, or, in scottish language, _fey_, arrived at a gallop, and prepared to cross the water. no remonstrance from the bystanders was of power to stop him: he plunged into the stream, and perished." so far sir walter. the ross-shire story is fuller, and somewhat different in its details. on a field in the near neighbourhood of the chapel, now laid out into the gardens of conon house, there was a party of highlanders engaged in an autumnal day at noon, some two or three centuries ago, in cutting down their corn, when the boding voice of the wraith was heard rising from the conon beneath--"the hour's come, but not the man." immediately after, a courier on horseback was seen spurring down the hill in hot haste, making directly for what is known as a "fause ford," that lies across the stream just opposite the old building, in the form of a rippling bar, which, indicating apparently, though very falsely, little depth of water, is flanked by a deep black pool above and below. the highlanders sprang forward to warn him of his danger, and keep him back; but he was unbelieving and in haste, and rode express, he said, on business that would brook no delay; and as for the "fause ford," if it could not be ridden, it could be swam; and, whether by riding or swimming, he was resolved on getting across. determined, however, on saving him in his own despite, the highlanders forced him from his horse, and, thrusting him into the little chapel, locked him in; and then, throwing open the door when the fatal hour had passed, they called to him that he might now pursue his journey. but there was no reply, and no one came forth; and on going in they found him lying cold and stiff, with his face buried in the water of a small stone font. he had fallen, apparently, in a fit, athwart the wall; and his predestined hour having come, he was suffocated by the few pints of water in the projecting font. at this time the stone font of the tradition--a rude trough, little more than a foot in diameter either way--was still to be seen among the ruins; and, like the veritable cannon in the castle of udolpho, beside which, according to annette, the ghost used to take its stand, it imparted by its solid reality a degree of authenticity to the story in this part of the country, which, if unfurnished with a "local habitation," as in sir walter's note, it would have wanted. such was one of the many stories of the conon with which i became acquainted at a time when the beliefs they exemplified were by no means quite dead, and of which i could think as tolerably serious realities, when, lying a-bed all alone at midnight, the solitary inmate of a dreary barrack, listening to the roar of the conon. besides the long evenings, we had an hour to breakfast, and another to dinner. much of the breakfast hour was spent in cooking our food; but as a bit of oaten cake and a draught of milk usually served us for the mid-day meal, the greater part of the hour assigned to _it_ was available for purposes of rest or amusement. and when the day was fine, i used to spend it by the side of a mossy stream, within a few minutes' walk of the work-shed, or in a neighbouring planting, beside a little irregular lochan, fringed round with flags and rushes. the mossy stream, black in its deeper pools, as if it were a rivulet of tar, contained a good many trout, which had acquired a hue nearly as deep as its own, and formed the very negroes of their race. they were usually of small size--for the stream itself was small; and, though little countries sometimes produce great men, little streams rarely produce great fish. but on one occasion, towards the close of autumn, when a party of the younger workmen set themselves, in a frolic, to sweep it with torch and spear, they succeeded in capturing, in a dark alder-o'ershaded pool, a monstrous individual, nearly three feet in length, and proportionally bulky, with a snout bent over the lower jaw at its symphysis, like the beak of a hawk, and as deeply tinged (though with more of brown in its complexion) as the blackest coal-fish i ever saw. it must have been a bull-trout, a visitor from the neighbouring river; but we all concluded at the time, from the extreme dinginess of its coat, that it had lived for years in its dark pool, a hermit apart from its fellows. i am not now, however, altogether certain that the inference was a sound one. some fishes, like some men, have a wonderful ability of assuming the colours that best suit their interests for the time. i have been unable to determine whether the trout be one of these conformists; but it used to strike me at this period as at least curious, that the fishes in even the lower reaches of the dark little rivulet should differ so entirely in hue from those of the greatly clearer conon, into which its peaty waters fall, and whose scaly denizens are of silvery brightness. no fish seems to possess a more complete power over its dingy coat than a very abundant one in the estuary of the conon--the common flounder. standing on the bank, i have startled these creatures from off the patch of bottom on which they lay--visible to only a very sharp eye--by pitching a very small pebble right over them. was the patch a pale one--for a minute or so they carried its pale colour along with them into some darker tract, where they remained distinctly visible from the contrast, until, gradually acquiring the deeper hue, they again became inconspicuous. but if startled back to the same pale patch from which they had set out, i have then seen them visible for a minute or so, from their over-dark tint, until, gradually losing it in turn, they paled down, as at first, to the colour of the lighter ground. an old highlander, whose suit of tartan conformed to the general hue of the heather, was invisible at a little distance, when traversing a moor, but came full into view in crossing a green field or meadow: the suit given by nature to the flounder, tinted apparently on the same principle of concealment, exhibits a degree of adaptation to its varying circumstances, which the tartan wanted. and it is certainly curious enough to find, in one of our commonest fishes, a property which used to be regarded as one of the standing marvels of the zoology of those remote countries of which the chameleon is a native. the pond in the piece of planting, though as unsightly a little patch of water as might be, was, i found, a greatly richer study than the dark rivulet. mean and small as it was--not larger in area inside its fringe of rushes than a fashionable drawing-room--its natural history would have formed an interesting volume; and many a half-hour have i spent beside it in the heat of the day, watching its numerous inhabitants--insect, reptilian, and vermiferous. there were two--apparently _three_--different species of libellula that used to come and deposit their eggs in it--one of the two, that large kind of dragon-fly (_eshna grandis_), scarce smaller than one's middle-finger--which is so beautifully coloured black and yellow, as if adorned by the same taste one sees displayed in the chariots and liveries of the fashionable world. the other fly was a greatly more slender and smaller species or genus, rather _agrion_; and it seemed two, not one, from the circumstance, that about one-half the individuals were beautifully variegated black and sky-blue, the other half black and bright crimson. but the peculiarity was merely a sexual one: as if in illustration of those fine analogies with which all nature is charged, the sexes put on the _complementary_ colours, and are mutually fascinating, not by resembling, but by _corresponding_ to, each other. i learned in time to distinguish the disagreeable-looking larvæ of these flies, both larger and smaller, with their six hairy legs, and their grotesque formidable vizors, and found that they were the very pirates of the water, as the splendid insects into which they were ultimately developed were the very tyrants of the lower air. it was strange to see the beautiful winged creature that sprang out of the pupa into which the repulsive-looking pirate had been transformed, launch forth into its new element, changed in everything save its nature, but still unchanged in that, and rendering itself as formidable to the moth and the butterfly as it had been before to the newt and the tadpole. there is, i daresay, an analogy here also. it is in the first state of our own species, as certainly as in that of the dragon-fly, that the character is fixed. further, i used to experience much interest in watching the progress of the frog, in its earlier stages from the egg to the fish; then from the fish to the reptile fish, with its fringed tail, and ventral and pectoral _limbs_; and, last of all, from the reptile fish to the complete reptile. i had not yet learned--nor was it anywhere known at the time--that the history of the individual frog, through these successive transformations, is a history in small of the animal creation itself in its earlier stages--that in order of time the egg-like mollusc had taken precedence of the fish, and the fish of the reptile; and that an intermediate order of creatures had once abounded, in which, as in the half-developed frog, the natures of both fish and reptile were united. but, though unacquainted with this strange analogy, the transformations were of themselves wonderful enough to fill for a time my whole mind. i remember being struck one afternoon, after spending my customary spare half hour beside the pond, and marking the peculiar style of colouring in the yellow and black libellulidæ in the common wasp, and in a yellow and black species of ichneumon fly, to detect in some half-dozen gentlemen's carriages that were standing opposite our work-shed--for the good old knight of conon house had a dinner-party that evening--exactly the same style of ornamental colouring. the greater number of the vehicles were yellow and black--just as these were the prevailing colours among the wasps and libellulidæ; but there was a slight admixture of other colours among them too: there was at least one that was black and green, or black and blue, i forget which; and another black and brown. and so it was among the insects also: the same sort of taste, both in colour and the arrangements of colour, and even in the proportions of the various colours, seemed to have regulated the style of ornament manifested in the carriages of the dinner party, and of the insect visitors of the pond. further, i thought i could detect a considerable degree of resemblance in form between a chariot and an insect. there was a great _abdominal_ body separated by a narrow isthmus from a _thoracic_ coach-box, where the directing power was stationed; while the wheels, poles, springs, and general framework on which the vehicle rested, corresponded to the wings, limbs, and antennæ of the insect. there was at least sufficient resemblance of form to justify resemblance of colour; and here _was_ the actual resemblance of colour which the resemblance of form justified. i remember that, in musing over the coincidence, i learned to suspect, for the first time, that it might be no mere coincidence after all; and that the fact embodied in the remarkable text which informs us that the creator made man in his own image, might in reality lie at its foundation as the proper solution. man, spurred by his necessities, has discovered for himself mechanical contrivances, which he has afterwards found anticipated as contrivances of the divine mind, in some organism, animal or vegetable. in the same way his sense of beauty in form or colour originates some pleasing combination of lines or tints; and then he discovers that _it_ also has been anticipated. he gets his chariot tastefully painted black and yellow, and lo! the wasp that settles on its wheel, or the dragon-fly that darts over it, he finds painted in exactly the same style. his neighbour, indulging in a different taste, gets _his_ vehicle painted black and blue, and lo! some lesser libellula or ichneumon fly comes whizzing past, to justify his style of ornament also, but at the same time to show that it, too, had existed ages before. the evenings gradually closed in as the season waned--at first abridging, and at length wholly interdicting, my evening walks; and having no other place to which to retire, save the dark, gousty hay-loft into which a light was never admitted, i had to seek the shelter of the barrack, and succeeded usually in finding a seat within at least _sight_ of the fire. the place was greatly over-crowded; and, as in all over-large companies, it had commonly its four or five groups of talkers; each group furnished with a topic of its own. the elderly men spoke about the state of the markets, and speculated, in especial, on the price of oatmeal; the apprentices talked about lasses; while knots of intermediate age discussed occasionally both markets and lasses too, or spoke of old companions, their peculiarities and history, or expatiated on the adventures of former work seasons, and the characters of the neighbouring lairds. politics proper i never heard. during the whole season a newspaper never once entered the barrack door. at times a song or story secured the attention of the whole barrack; and there was in especial one story-teller whose powers of commanding attention were very great. he was a middle-aged highlander, not very skilful as a workman, and but indifferently provided with english; and as there usually attaches a nickname to persons in the humbler walks that are marked by any eccentricity of character, he was better known among his brother workmen as jock mo-ghoal, _i.e._ john my darling, than by his proper name. of all jock mo-ghoal's stories jock mo-ghoal was himself the hero; and certainly most wonderful was the invention of the man. as recorded in his narratives, his life was one long epic poem, filled with strange and startling adventure, and furnished with an extraordinary machinery of the wild and supernatural; and though all knew that jock made imagination supply, in his histories, the place of memory, not even ulysses or Ã�neas--men who, unless very much indebted to their poets, must have been of a similar turn--could have attracted more notice at the courts of alcinuous or dido, than jock in the barrack. the workmen used, on the mornings after big greater narratives, to look one another full in the face, and ask, with a smile rather incipient than fully manifest, whether "jock wasna perfectly wonderfu' last nicht?" he had several times visited the south of scotland, as one of a band of highland reapers, for employment in his proper profession very often failed poor jock; and these journeys formed the grand occasions of his adventures. one of his narratives commenced, i remember, with a frightful midnight scene in a solitary churchyard. jock had lost his way in the darkness; and, after stumbling among burial-mounds and tombstones, he had toppled into an open grave, which was of a depth so profound, that for some time he failed to escape from it, and merely pulled down upon himself, in his attempts to climb its loose sides, musty skulls, and great thigh-bones, and pieces of decayed coffins. at length, however, he did succeed in getting out, just as a party of unscrupulous resurrectionists were in the act of entering the burying-ground; and they, naturally enough preferring an undecayed subject that had the life in it to preserve it fresh, to dead corpses the worse for the keeping, gave him chase; and it was with the extremest difficulty that, after scudding over wild moors and through dark woods, he at length escaped them by derning himself in a fox-earth. the season of autumnal labour over, he visited edinburgh on his way north; and was passing along the high street, when, seeing a highland girl on the opposite side with whom he was intimate, and whom he afterwards married, he strode across to address her, and a chariot coming whirling along the street at the time at full speed, he was struck by the pole and knocked down. the blow had taken him full on the chest; but though the bone seemed injured, and the integuments became frightfully swollen and livid, he was able to get up; and, on asking to be shown the way to a surgeon's shop, his acquaintance the girl brought him to an under-ground room in one of the narrow lanes off the street, which, save for the light of a great fire, would have been pitch dark at mid-day, and in which he found a little wrinkled old woman, as yellow as the smoke that filled the apartment. "choose," said the hag, as she looked at the injured part, "one of two things--a cure slow but sure, or sudden but imperfect. or shall i put back the hurt altogether till you get home?" "that, that," said jock; "if i were ance home i could bear it well enouch." the hag began to pass her hand over the injured part, and to mutter under her breath some potent charm; and as she muttered and manipulated, the swelling gradually subsided, and the livid tints blanched, till at length nought remained to tell of the recent accident save a pale spot in the middle of the breast, surrounded by a thread-like circle of blue. and now, she said, you are well for three weeks; but be prepared for the fourth. jock prosecuted his northward journey, and encountered the usual amount of adventure by the way. he was attacked by robbers, but, assistance coming up, he succeeded in beating them off. he lost his way in a thick mist, but found shelter, after many hours' wandering far among the hills, in a deserted shepherd's shielin'. he was nearly buried in a sudden snow-storm that broke out by night, but, getting into the middle of a cooped-up flock of sheep, they kept him warm and comfortable amid the vast drift-wreaths, till the light of morning enabled him to prosecute his journey. at length he reached home, and was prosecuting his ordinary avocations, when the third week came to a close; and he was on a lonely moor at the very hour he had met with the accident on the high street, when he suddenly heard the distant rattle of a chariot, though not a shadow of the vehicle was to be seen; the sounds came bearing down upon him, heightening as they approached, and, when at the loudest, a violent blow on the breast prostrated him on the moor. the stroke of the high street "had come back," just as the wise woman had said it would, though with accompaniments that jock had not anticipated. it was with difficulty he reached his cottage that evening; and there elapsed fully six weeks ere he was able to quit it again. such, in its outlines, was one of the marvellous narratives of jock mo-ghoal. he belonged to a curious class, known by specimen, in, i suppose, almost every locality, especially in the more primitive ones--for the smart ridicule common in the artificial states of society greatly stunt their growth; and in our literature--as represented by the bobadils, young wildings, caleb balderstons, and baron munchausens--they hold a prominent place. the class is to be found of very general development among the vagabond tribes. i have listened to wonderful personal narratives that had not a word of truth in them, "from gipsies brown in summer glades that bask," as i took my seat beside their fire, in a wild rock-cave in the neighbourhood of rosemarkie, or at a later period in the cave of marcus; and in getting into conversation with individuals of the more thoroughly lapsed classes of our large towns, i have found that a faculty of extemporary fabrication was almost the only one which i could calculate on finding among them in a state of vigorous activity. that in some cases the propensity should be found co-existing with superior calibre and acquirement, and with even a sense of honour by no means very obtuse, must be regarded as one of the strange anomalies which so often surprise and perplex the student of human character. as a misdirected toe-nail, injured by pressure, sometimes turns round, and, re-entering the flesh, vexes it into a sore, it would seem as if that noble inventive faculty to which we owe the parable and the epic poem, were liable, when constrained by self-love, to similar misdirections; and certainly, when turned inwards upon its possessor, the moral character festers or grows callous around it. there was no one in the barrack with whom i cared much to converse, or who, in turn, cared much to converse with me; and so i learned, on the occasions when the company got dull, and broke up into groups, to retire to the hay-loft where i slept, and pass there whole hours seated on my chest. the loft was a vast apartment, some fifty or sixty feet in length, with its naked rafters raised little more than a man's height over the floor; but in the starlit nights, when the openings in the wall assumed the character of square patches of darkness-visible stamped upon utter darkness, it looked quite as well as any other unlighted place that could not be seen; and in nights brightened by the moon, the pale beams, which found access at openings and crevices, rendered its wide area quite picturesque enough for ghosts to walk in. but i never saw any; and the only sounds i heard were those made by the horses in the stable below, champing and snorting over their food. they were, i doubt not, happy enough in their dark stalls, because they were horses, and had plenty to eat; and i was at times quite happy enough in the dark loft above, because i was a man, and could think and imagine. it is, i believe, addison who remarks, that if all the thoughts which pass through men's minds were to be made public, the great difference which seems to exist between the thinking of the wise and of the unwise would be a good deal reduced; seeing that it is a difference which does not consist in their not having the same weak thoughts in common, but merely in the prudence through which the wise suppress their foolish ones. i still possess notes of the cogitations of these solitary evenings, ample enough to show that they were extraordinary combinations of the false and the true; but i at the same time hold them sufficiently in memory to remember, that i scarce, if at all, distinguished between what was false and true in them at the time. the literature of almost every people has a corresponding early stage, in which fresh thinking is mingled with little conceits, and in which the taste is usually false, but the feeling true. let me present my young readers, from my notes, with the variously compounded cogitations of one of these quiet evenings. what formed so long ago one of my exercises may now form one of theirs, if they but set themselves to separate the solid from the unsolid thinking contained in my abstract. musings. "i stood last summer on the summit of tor-achilty [a pyramidal hill about six miles from conon side], and occupied, when there, the centre of a wide circle, about fifty miles in diameter. i can still call up its rough-edged sea of hills, with the clear blue firmament arching over, and the slant rays of the setting sun gleaming athwart. yes, over that circular field, fifty miles across, the firmament closed all around at the horizon, as a watch-glass closes round the dial-plate of the watch. sky and earth seemed co-extensive; and yet how incalculably vast their difference of area! thousands of systems seemed but commensurate, to the eye, with a small district of earth fifty miles each way. but capacious as the human imagination has been deemed, can it conceive of an area of wider field? mine cannot. my mind cannot take in more at a glance, if i may so speak, than is taken in by the eye. i cannot conceive of a wider area than that which the sight commands from the summit of a lofty eminence. i can pass in imagination through many such areas. i can add field to field _ad infinitum_; and thus conceive of infinite space, by conceiving of a space which can be infinitely added to; but all of space that i can take in at one process, is an area commensurate with that embraced at a glance by the eye. how, then, have i my conception of the earth as a whole--of the solar system as a whole--nay, of many systems as a whole? just as i have my conceptions of a school-globe or of an orrery--by diminution. it is through the diminution induced by distance that the sidereal heavens only co-extend, as seen from the top of tor-achilty, with a portion of the counties of ross and inverness. the apparent area is the same, but the colouring is different. our ideas of greatness, then, are much less dependent on actual area than on what painters term aerial perspective. the dimness of distance, and the diminution of parts, are essential to right conceptions of great magnitude. "of the various figures presented to me here, i seize strong hold of but one. i brood over the picture of the solar system conjured up. i conceive of the satellites as light shallops that continually sail round heavier vessels, and consider how much more of space they must traverse than the orbs to which they are attached. the entire system is presented to me as an orrery of the apparent size of the area of landscape seen from the hill-top; but dimness and darkness prevent the diminution from communicating that appearance of littleness to the whole which would attach to it, were it, like an actual orrery, sharply defined and clear. as the picture rises before me, the entire system seems to possess, what i suspect it wants, its atmosphere like that of the earth, which reflects the light of the sun in the different degrees of excessive brightness--noon-tide splendour, the fainter shades of evening, and grey twilight obscurity. this veil of light is thickest towards the centre of the system; for when the glance rests on its edges, the suns of other systems may be seen peeping through. i see mercury sparkling to the sun, with its oceans of molten glass, and its fountains of liquid gold. i see the ice-mountains of saturn, hoar through the twilight. i behold the earth rolling upon itself, from darkness to light, and from light to darkness. i see the clouds of winter settling over one part of it, with the nether mantle of snow shining through them; i see in another a brown, dusky waste of sand lighted up by the glow of summer. one ocean appears smooth as a mirror--another is black with tempest. i see the pyramid of shade which each of the planets casts from its darkened side into the space behind; and i perceive the stars twinkling through each opening, as through the angular doors of a pavilion. "such is the scene seen at right angles with the plane in which the planets move; but what would be its aspect if i saw it in the line of the plane? what would be its appearance if i saw it edgewise? there arises in my mind one of those uncertainties which so frequently convince me that i am ignorant. i cannot complete my picture, for i do not know whether all the planets move in one plane. how determine the point? a ray of light breaks in. huzza! i have found it. if the courses of the planets as seen in the heavens form parallel lines, then must they all move in one plane; and _vice versa_. but hold! that would be as seen from the sun--if the planets _could_ be seen from the sun. the earth is but one of their own number, and from it the point of view must be disadvantageous. the diurnal motion must perplex. but no. the apparent motion of the heavens need not disturb the observation. let the course of the planets through the fixed stars, be marked, and though, from the peculiarity of the point of observation, their motion may at one time seem more rapid, and at another more slow, yet, if their plane be, as a workman would say, _out of twist_, their lines will seem parallel. still in some doubt, however: i long for a glance at an orrery, to determine the point; and then i remember that ferguson, an untaught man like myself, had made more orreries than any one else, and that mechanical contrivances of the kind were the natural recourse of a man unskilled in the higher geometry. but it would be better to be a mathematician than skilful in contriving orreries. a man of the newtonian cast of mind, and accomplished in the newtonian learning, could solve the problem where i sat, without an orrery. "from the thing contemplated, i pass to the consideration of the mind that contemplates. oh! that wonderful newton, respecting whom the frenchman inquired whether he ate and slept like other men! i consider how one mind excels another; nay, how one man excels a thousand; and, by way of illustration, i bethink me of the mode of valuing diamonds. a single diamond that weighs fifty carats is deemed more valuable than two thousand diamonds, each of which only weighs one. my illustration refers exclusively to the native powers; but may it not, i ask, bear also on the acquisition of knowledge? every new idea added to the stock already collected is a carat added to the diamond; for it is not only valuable in itself, but it also increases the value of all the others, by giving to each of them a new link of association. "the thought links itself on to another, mayhap less sound:--do not the minds of men of exalted genius, such as homer, milton, shakspere, seem to partake of some of the qualities of infinitude? add a great many bricks together, and they form a pyramid as huge as the peak of teneriffe. add all the common minds together that the world ever produced, and the mind of a shakspere towers over the whole, in all the grandeur of unapproachable infinity. that which is infinite admits of neither increase nor diminution. is it not so with genius of a certain altitude? homer, milton, shakspere, were perhaps men of equal powers. homer was, it is said, a beggar; shakspere an illiterate wool-comber; milton skilled in all human learning. but they have all risen to an equal height. learning has added nothing to the _illimitable_ genius of the one; nor has the want of it detracted from the _infinite_ powers of the others. but it is time that i go and prepare supper." i visited the policies of conon house a full quarter of a century after this time--walked round the kiln, once our barrack--scaled the outside stone-stair of the hay-loft, to stand for half a minute on the spot where i used to spend whole hours seated on my chest, so long before; and then enjoyed a quiet stroll among the woods of the conon. the river was big in flood: it was exactly such a river conon as i had lost sight of in the winter of , and eddied past dark and heavy, sweeping over bulwark and bank. the low-stemmed alders that rose on islet and mound seemed shorn of half their trunks in the tide; here and there an elastic branch bent to the current, and rose and bent again; and now a tuft of withered heath came floating down, and now a soiled wreath of foam. how vividly the past rose up before me!--boyish day-dreams, forgotten for twenty years--the fossils of an early formation of mind, produced at a period when the atmosphere of feeling was warmer than now, and the immaturities of the mental kingdom grew rank and large, like the ancient _cryptogamia_, and bore no specific resemblance to the productions of a riper time. the season i had passed in the neighbourhood so long before--the first i had anywhere spent among strangers--belonged to an age when home is not a country, nor a province even, but simply a little spot of earth, inhabited by friends and relatives; and the verses, long forgotten, in which my joy had found vent when on the eve of returning to that home, came chiming as freshly into my memory as if scarce a month had passed since i had composed them beside the conon. here they are, with all the green juvenility of the home-sickness still about them--a true petrifaction of an extinct feeling:-- to the conon. conon, fair flowed thy mountain stream, through blossom'd heath and ripening field. when, shrunk by summer's fervid beam, thy peaceful waves i first beheld. calmly they swept thy winding shore. when harvest's mirthful feast was nigh-- when, breeze-borne, with thy hoarser roar came mingling sweet the reapers' cry. but now i mark thy angry wave rush headlong to the stormy sea; wildly the blasts of winter rave, sad rustling through the leafless tree loose on its spray the alder leaf hangs wavering, trembling, sear and brow and dark thy eddies whirl beneath, and white thy foam comes floating down. thy banks with withered shrubs are spread; thy fields confess stern winter's reign; and gleams yon thorn with berries red, like banner on a ravaged plain. hark! ceaseless groans the leafless wood; hark! ceaseless roars thy stream below ben-vaichard's peaks are dark with cloud ben-weavis' crest is white with snow. and yet, though red thy stream comes down though bleak th' encircling hills appear-- though field be bare, and forest brown, and winter rule the waning year-- unmoved i see each charm decay, unmourn'd the sweets of autumn die; and fading flower and leafless spray court all in vain the thoughtful sigh. not that dull grief delights to see vex'd nature wear a kindred gloom; not that she smiled in vain to me, when gaily prank'd in summer's bloom nay, much i loved, at even-tide, through brahan's lonely woods to stray. to mark thy peaceful billows glide, and watch the sun's declining ray. but yet, though roll'd thy billows fair as e'er roll'd those of classic stream-- though green thy woods, now dark and bare, bask'd beauteous in the western beam; to mark a scene that childhood loved, the anxious eye was turned in vain; nor could i find the friend approved, that shared my joy or soothed my pain. now winter reigns: these hills no more shall sternly bound my anxious view soon, bent my course to croma's shore, shall i yon winding path pursue. fairer than _here_ gay summer's glow to me _there_ wintry storms shall seem then blow, ye bitter breezes, blow, and lash the conon's mountain stream. chapter xi. "the bounding pulse, the languid limb the changing spirit's rise and fall-- we know that these were felt by him, for these are felt by all."--montgomery. the apprenticeship of my friend william ross had expired during the working season of this year, when i was engaged at conon-side; and he was now living in his mother's cottage in the parish of nigg, on the ross-shire side of the cromarty firth. and so, with the sea between us, we could no longer meet every evening as before, or take long night-walks among the woods. i crossed the firth, however, and spent one happy day in his society, in a little, low-roofed domicile, with a furze-roughened ravine on the one side, and a dark fir-wood on the other; and which, though picturesque and interesting as a cottage, must, i fear, have been a very uncomfortable home. his father, whom i had not before seen, was sitting beside the fire as i entered. in all except expression he was wonderfully like my friend; and yet he was one of the most vapid men i ever knew--a man literally without an idea, and almost without a recollection or a fact. and my friend's mother, though she showed a certain kindliness of disposition which her husband wanted, was loquacious and weak. had my quondam acquaintance, the vigorous-minded maniac of ord, seen william and his parents, she would have triumphantly referred to them in evidence that flavel and the schoolmen were wholly in the right in holding that souls are not "derived through parental traduction." my friend had much to show me: he had made an interesting series of water-colour sketches of the old castles of the neighbourhood, and a very elaborate set of drawings of what are known as the runic obelisks of ross: he had made some first attempts, too, in oil-painting; but though his drawing was, as usual, correct, there was a deadness and want of transparency about his colouring, which characterized all his after attempts in the same department, and which was, i suspect, the result of some such deficiency in his perceptions of the harmonies of colour as that which, in another department of sense, made me so insensible to the harmonies of sound. his drawings of the obelisks were of singular interest. not only have the thirty years which have since elapsed exerted their dilapidating effect on all the originals from which he drew, but one of the number--the most entire of the group at that time--has been since almost wholly destroyed; and so, what he was then able to do, there can be no such opportunity of doing again. further, his representations of the sculptured ornaments, instead of being (what those of artists too often are) mere picturesque approximations, were true in every curve and line. he told me he had spent a fortnight in tracing out the involved mathematical figures, curves, circles, and right lines--on which the intricate fretwork of one of the obelisks was formed, and in making separate drawings of each compartment, before commencing his draught of the entire stone. and, looking with the eye of the stone-cutter at his preliminary sketches, from the first meagre lilies that formed the ground-work of some involved and difficult knot, to the elaborate knot itself, i saw that, with such a series of drawings before me, i myself could learn to cut runic obelisks, in all the integrity of the complex ancient style, in less than a fortnight. my friend had formed some striking and original views regarding the theology represented by symbol on these ancient stones--at that time regarded as runic, but now held to be rather of celtic origin. in the centre of each obelisk, on the more important and strongly relieved side, there always occurs a large cross, rather of the greek than of the roman type, and usually elaborately wrought into a fretwork, composed of myriads of snakes, raised in some of the compartments over half-spheres resembling apples. in one of the ross-shire obelisks--that of shadwick, in the parish of nigg--the cross is entirely composed of these apple-like, snake-covered protuberances; and it was the belief of my friend, that the original idea of the whole, and, indeed, the fundamental idea of this school of sculpture, was exactly that so emphatically laid down by milton in the opening argument of his poem--man's fall symbolized by the serpents and the apples, and the great sign of his restoration, by the cross. but in order to indicate that to the divine man, the restorer, the cross itself was a consequence of the fall, even it was covered over with symbols of the event, and, in one curious specimen, built up of them. it was the snakes and apples that had reared, _i.e._, rendered imperative, the cross. my friend further remarked, that from this main idea a sort of fretwork had originated, which seemed more modern in some of its specimens than the elaborately-carved snakes, and strongly-relieved apples, but in which the twistings of the one, and the circular outlines of the others might be distinctly traced; and that it seemed ultimately to have passed from a symbol into a mere ornament; as, in earlier instances, hieroglyphic pictures had passed into mere arbitrary signs or characters. i know not what may be thought of the theory of william ross; but when, in visiting, several years ago, the ancient ruins of iona, i marked, on the more ancient crosses, the snakes and apparent apples, and then saw how the same combination of figures appeared as mere ornamental fretwork on some of the later tombs, i regarded it as more probably the right one than any of the others i have yet seen broached on the subject. i dined with my friend this day on potatoes and salt, flanked by a jug of water; nor were the potatoes by any means very good ones; but they formed the only article of food in the household at the time. he had now dined and breakfasted upon them, he said, for several weeks together; but though not very strengthening, they kept in the spark of life; and he had saved up money enough to carry him to the south of scotland in the spring, where he trusted to find employment. a poor friendless lad of genius, diluting his thin consumptive blood on bad potatoes and water, and, at the same time, anticipating the labours of our antiquarian societies by his elaborate and truthful drawings of an interesting class of national antiquities, must be regarded as a melancholy object of contemplation; but such hapless geniuses there are in every age in which art is cultivated, and literature has its admirers; and, shrinkingly modest and retiring in their natures, the world rarely finds them out in time. i found employment enough for my leisure during this winter in my books and walks, and in my uncle james's workshop, which, now that uncle james had no longer to lecture me about my latin, and my carelessness as a scholar in general, was a very pleasant place, where a great deal of sound remark and excellent information were always to be had. there was another dwelling in the neighbourhood in which i sometimes spent a not unpleasant hour. it was a damp underground room, inhabited by a poor old woman, who had come to the town from a country parish in the previous year, bringing with her a miserably deformed lad, her son, who, though now turned of twenty, more resembled, save in his head and face, a boy of ten, and who was so helpless a cripple, that he could not move from off his seat. "poor lame danie," as he was termed, was, notwithstanding the hard measure dealt him by nature, an even-tempered, kindly-dispositioned lad, and was, in consequence, a great favourite with the young people in the neighbourhood, especially with the humbly taught young women, who--regarding him simply as an intelligence, coupled with sympathies, that could write letters--used to find him employment, which he liked not a little, as a sort of amanuensis and adviser-general in their affairs of the heart. richardson tells that he learned to write his pamela by the practice he acquired in writing love-letters, when a very young lad, for half a score love-sick females, who trusted and employed him. "poor danie," though he bore on a skeleton body, wholly unfurnished with muscle, a brain of the average size and activity, was not born to be a novelist; but he had the necessary materials in abundance; and though secret enough to all his other acquaintance, i, who cared not a great deal about the matter, might, i found, have as many of his experiences as i pleased. i enjoyed among my companions the reputation of being what they termed "close-minded;" and danie, satisfied, in some sort, that i deserved the character, seemed to find it a relief to roll over upon my shoulders the great weight of confidence which, rather liberally, as would seem, for his comfort, had been laid upon his own. it is recorded of himself by burns, that he "felt as much pleasure in being in the secret of half the loves of the parish of tarbolton, as ever did statesman in knowing the intrigues of half the courts of europe." and, writing to dr. moore, he adds, that it was "with difficulty" his pen was "restrained from giving him a couple of paragraphs on the love-adventures of his compeers, the humble inmates of the farm-house and cottage." i, on the other hand, bore my confidences soberly enough, and kept them safe and very close--regarding myself as merely a sort of back-yard of mind, in which danie might store up at pleasure the precious commodities intrusted to his charge, which, from want of stowage, it cumbered him to keep, but which were his property, not mine. and though, i daresay, i could still fill more than "a couple of paragraphs" with the love-affairs of townswomen, some of whose daughters were courted and married ten years ago, i feel no inclination whatever, after having kept their secrets so long, to begin blabbing them now. danie kept a draft-board, and used to take a pride in beating all his neighbours; but in a short time he taught me--too palpably to his chagrin--to beat himself; and finding the game a rather engrossing one besides, and not caring to look on the woe-begone expression that used to cloud the meek pale face of my poor acquaintance, every time he found his men swept off the board, or cooped up into a corner, i gave up drafts, the only game of the kind of which i ever knew anything, and in the course of a few years succeeded in unlearning pretty completely all the moves. it appeared wonderful that the processes essential to life could have been carried on in so miserable a piece of framework as the person of poor danie: it was simply a human skeleton bent double, and covered with a sallow skin. but they were not carried on in it long. about eighteen months after the first commencement of our acquaintance, when i was many miles away, he was seized by a sudden illness, and died in a few hours. i have seen, in even our better works of fiction, less interesting characters portrayed than, poor gentle-spirited danie, the love-depository of the young dames of the village; and i learned a thing or two in his school. it was not until after several weeks of the working season had passed, that my master's great repugnance to doing nothing overcame his almost equally great repugnance again to seek work as a journeyman. at length, however, a life of inactivity became wholly intolerable to him; and, applying to his former employer, he was engaged on the previous terms--full wages for himself, and a very small allowance for his apprentice, who was now, however, recognised as the readier and more skilful stone-cutter of the two. in cutting mouldings of the more difficult kinds, i had sometimes to take the old man under charge, and give him lessons in the art, from which, however, he had become rather too rigid in both mind and body greatly to profit. we both returned to conon-side, where there was a tall dome of hewn work to be erected over the main archway of the steading at which we had been engaged during the previous year; and, as few of the workmen had yet assembled on the spot, we succeeded in establishing ourselves as inmates of the barrack, leaving the hay-loft, with its inferior accommodation, to the later comers. we constructed for ourselves a bed-frame of rough slabs, and filled it with hay; placed our chests in front of it; and, as the rats mustered by thousands in the place, suspended our sack of oatmeal by a rope, from one of the naked rafters, at rather more than a man's height over the floor. and, having both pot and pitcher, our household economy was complete. though resolved not to forego my evening walks, i had determined to conform also to every practice of the barrack; and as the workmen, drafted from various parts of the country, gradually increased around us, and the place became crowded, i soon found myself engaged in the rolicking barrack-life of the north-country mason. the rats were somewhat troublesome. a comrade who slept in the bed immediately beside ours had one of his ears bitten through one night as he lay asleep, and remarked, that he supposed it would be his weasand they would attack next time; and, on rising one morning, i found that the four brightly plated jack-buttons to which my braces had been fastened had been fairly cut from off my trousers, and carried away, to form, i doubt not, a portion of some miser-hoard in the wall. but even the rats themselves became a source of amusement to us, and imparted to our rude domicile, in some little degree, the dignity of danger. it was not likely that they would succeed in eating us all up, as they had done wicked bishop hatto of old; but it was at least something that they had begun to try. the dwellers in the hay-loft had not been admitted in the previous season to the full privileges of the barrack, nor had they been required to share in all its toils and duties. they had to provide their quota of wood for the fire, and of water for general household purposes: but they had not to take their turn of cooking and baking for the entire mess, but were permitted, as convenience served, to cook and bake for themselves. and so, till now, i had made cakes and porridge, with at times an occasional mess of brose or _brochan_, for only my master and myself--a happy arrangement, which, i daresay, saved me a few _rammings_; seeing that, in at least my earlier efforts, i had been rather unlucky as a cook, and not very fortunate as a baker. my experience in the cromarty caves had rendered me skilful in both boiling and roasting potatoes, and in preparing shell-fish for the table, whether molluscous or crustacean, according to the most approved methods; but the exigencies of our wild life had never brought me fairly in contact with the cerealia; and i had now to spoil a meal or two, in each instance, ere my porridge became palatable, or my cakes crisp, or my brose free and knotty, or my _brochan_ sufficiently smooth and void of knots. my master, poor man, did grumble a little at first; but there was a general disposition in the barrack to take part rather with his apprentice than with himself; and after finding that the cases were to be given against him, he ceased making complaints. my porridge was at times, i must confess, very like leaven; but then, it was a standing recipe in the barrack, that the cook should continue stirring the mess and adding meal, until, from its first wild ebullitions in full boil, it became silent over the fire; and so i could show that i had made my porridge like leaven, quite according to rule. and as for my _brochan_, i succeeded in proving that i had actually failed to satisfy, though i had made two kinds of it at once in the same pot. i preferred this viand when of a thicker consistency than usual, whereas my master liked it thin enough to be drunk out of the bowl; but as it was i who had the making of it, i used more instead of less meal than ordinary, and unluckily, in my first experiment, mixed up the meal in a very small bowl. it became a dense dough-like mass; and on emptying it into the pot, instead of incorporating with the boiling water, it sank in a solid cake to the bottom. in vain i stirred, and manipulated, and kept up the fire. the stubborn mass refused to separate or dilute, and at length burnt brown against the bottom of the pot--a hue which the gruel-like fluid which floated over also assumed; and at length, in utter despair of securing aught approaching to an average consistency for the whole, and hearing my master's foot at the door, i took the pot from off the fire, and dished up for supper a portion of the thinner mixture which it contained, and which, in at least colour and consistency, not a little resembled chocolate. the poor man ladled the stuff in utter dismay. "od, laddie," he said, "what ca' ye this? ca' ye this _brochan_?" "onything ye like, master," i replied; "but there are two kinds in the pot, and it will go hard if none of them please you." i then dished him a piece of the cake, somewhat resembling in size and consistency a small brown dumpling, which he of course found wholly inedible, and became angry. but this bad earth of ours "is filled," according to cowper, "with wrong and outrage;" and the barrack laughed and took part with the defaulter. experience, however, that does so much for all, did a little for me. i at length became a tolerably fair plain cook, and not a very bad baker; and now, when the exigencies required that i should take my full share in the duties of the barrack, i was found adequate to their proper fulfilment. i made cakes and porridge of fully the average excellence; and my brose and _brochan_ enjoyed at least the negative happiness of escaping animadversion and comment. some of the inmates, however, who were exceedingly nice in their eating, were great connoisseurs in porridge; and it was no easy matter to please them. there existed unsettled differences--the results of a diversity of tastes--regarding the time that should be given to the boiling of the mess, respecting the proportion of salt that should be allotted to each individual, and as to whether the process of "mealing," as it was termed, should be a slow or a hasty one, and, of course, as in all controversies of all kinds, the more the matters in dispute were discussed, the more did they grow in importance. occasionally the disputants had their porridge made at the same time in the same pot: there were, in especial, two of the workmen who differed upon the degree-of-salt question, whose bickers were supplied from the same general preparation; and as these had usually opposite complaints to urge against the cooking, their objections served so completely to neutralize each other, that they in no degree told against the cook. one morning the cook--a wag and a favourite--in making porridge for both the controversialists, made it so exceedingly fresh as to be but little removed from a poultice; and, filling with the preparation in this state the bicker of the salt-loving connoisseur, he then took a handful of salt, and mixing it with the portion which remained in the pot, poured into the bicker of the fresh man, porridge very much akin to a pickle. both entered the barrack sharply set for breakfast, and sat down each to his meal; and both at the first spoonful dropped their spoons. "a ramming to the cook!" cried the one--"he has given me porridge without salt!" "a ramming to the cook!" roared out the other--"he has given me porridge like brine!" "you see, lads," said the cook, stepping out into the middle of the floor, with the air of a much-injured orator--"you see, lads, what matters have come to at last: there is the very pot in which i made in one mess the porridge in both their bickers. i don't think we should bear this any longer; we have all had our turn of it, though mine happens to be the worst; and i now move that these two fellows be rammed." no sooner said than done. there was a terrible struggling, and a burning sense of injustice; but no single man in the barrack was match for half-a-dozen of the others. the disputants, too, instead of making common cause together, were prepared to assist in ramming each the other; and so rammed they both were. and at length, when the details of the stratagem came out, the cook--by escaping for half an hour into the neighbouring wood, and concealing himself there, like some political exile under ban of the government--succeeded in escaping the merited punishment. the cause of justice was never, i found, in greater danger in our little community, than when a culprit succeeded in getting the laughers on his side. i have said that i became a not very bad baker. still less and less sorely, as i improved in this useful art, did my cakes try the failing teeth of my master, until at length they became crisp and nice; and he began to find that my new accomplishment was working serious effects upon the contents of his meal-chest. with a keenly whetted appetite, and in vigorous health, i was eating a great deal of bread; and, after a good deal of grumbling, he at length laid it down as law that i should restrict myself for the future to two cakes per week. i at once agreed; but the general barrack, to whose ears some of my master's remonstrances had found their way, was dissatisfied; and it would probably have overturned in conclave our agreement, and punished the old man, my master, for the niggardly stringency of his terms, had i not craved, by way of special favour, to be permitted to give them a week's trial. one evening early in the week, when the old man had gone out, i mixed up the better part of a peck of meal in a pot, and placing two of the larger chests together in the same plane, kneaded it out into an enormous cake, at least equal in area to an ordinary-sized newcastle grindstone. i then cut it up into about twenty pieces, and, forming a vast semicircle of stones round the fire, raised the pieces to the heat in a continuous row, some five or six feet in length. i had ample and ready assistance vouchsafed me in the "firing"--half the barrack were engaged in the work--when my master entered, and after scanning our employment in utter astonishment--now glancing at the ring of meal which still remained on the united chests, to testify to the huge proportions of the disparted bannock, and now at the cones, squares, rhombs, and trapeziums of cake that hardened to the heat in front of the fire, he abruptly asked--"what's this, laddie?--are ye baking for a wadding?" "just baking one of the two cakes, master," i replied; "i don't think we'll need the other one before saturday night." a roar of laughter from every corner of the barrack precluded reply; and in the laughter, after an embarrassed pause, the poor man had the good sense to join. and during the rest of the season i baked as often and as much as i pleased. it is, i believe, goldsmith who remarks, that "wit generally succeeds more from being happily addressed, than from its native poignancy," and that "a jest calculated to spread at a gaming table, may be received with perfect indifference should it happen to drop in a mackerel-boat." on goldsmith's principle, the joke of what was termed, from the well-known fairy tale, "the big bannock wi' the malison," could have perhaps succeeded in only a masons' barrack; but never there at least could joke have been more successful. as i had not yet ascertained that the old red sandstone of the north of scotland is richly fossiliferous, conon-side and its neighbourhood furnished me with no very favourable field for geologic exploration. it enabled me, however, to extend my acquaintance with the great conglomerate base of the system, which forms here, as i have already said, a sort of miniature highlands, extending between the valleys of the conon and the peffer, and which--remarkable for its picturesque cliffs, abrupt eminences, and narrow steep-sided dells--bears in its centre a pretty wood-skirted loch, into which the old celtic prophet kenneth ore, when, like prospero, he relinquished his art, buried "deep beyond plummet sound" the magic stone in which he was wont to see both the distant and the future. immediately over the pleasure-grounds of brahan, the rock forms exactly such cliffs as the landscape gardener would make, if he could--cliffs with their rude prominent pebbles breaking the light over every square foot of surface, and furnishing footing, by their innumerable projections, to many a green tuft of moss, and many a sweet little flower; while far below, among the deep woods, there stand up enormous fragments of the same rock, that must have rolled down in some remote age from the precipices above, and which, mossy and hoar, and many of them ivy-bound, resemble artificial ruins--obnoxious, however, to none of the disparaging associations which the make-believe ruin is sure always to awaken. it was inexpressibly pleasant to spend a quiet evening hour among these wild cliffs, and imagine a time when the far distant sea beat against their bases; but though their enclosed pebbles evidently owed their rounded form to the attrition of water, the imagination seemed paralyzed when it attempted calling up a still earlier time, when these solid rocks existed as but loose sand and pebbles, tossed by waves or scattered by currents; and when, for hundreds and thousands of square miles, the wild tract around existed as an ancient ocean, skirted by unknown lands. i had not yet collected enough of geologic fact to enable me to grapple with the difficulties of a restoration of the more ancient time. there was a later period, also, represented in the immediate neighbourhood by a thick deposit of stratified sand, of which i knew as little as of the conglomerate. we dug into it, in founding a thrashing-mill, for about ten feet, but came to no bottom; and i could see that it formed the subsoil of the valley all around the policies of conon-side, and underlay most of its fields and woods. it was white and pure, as if it had been washed by the sea only a few weeks previous; but in vain did i search its beds and layers for a fragment of shell by which to determine its age. i can now, however, entertain little doubt that it belonged to the boulder clay period of submergence, and that the fauna with which it was associated bore the ordinary sub-arctic character. when this stratified sand was deposited, the waves must have broken against the conglomerate precipices of brahan, and the sea have occupied, as firths and sounds, the deep highland valleys of the interior. and on such of the hills of the country as had their heads above water at the time, that interesting but somewhat meagre alpine flora must have flourished, which we now find restricted to our higher mountain summits. once every six weeks i was permitted to visit cromarty, and pass a sabbath there; but as my master usually accompanied me, and as the way proved sufficiently long and weary to press upon his failing strength and stiffening limbs, we had to restrict ourselves to the beaten road, and saw but little. on, however, one occasion this season, i journeyed alone, and spent so happy a day in finding my homeward road along blind paths--that ran now along the rocky shores of the cromarty firth in its upper reaches, now through brown, lonely moors, mottled with danish encampments, and now beside quiet, tomb-besprinkled burying-grounds, and the broken walls of deserted churches--that its memory still lives freshly in my mind, as one of the happiest of my life. i passed whole hours among the ruins of craighouse--a grey fantastic rag of a castle, consisting of four heavily-arched stories of time-eaten stone, piled over each other, and still bearing a-top its stone roof and its ornate turrets and bartizans-- "a ghastly prison, that eternally hangs its blind visage out to the one sea." it was said in these days to be haunted by its goblin--a miserable-looking, grey-headed, grey-bearded, little old man, that might be occasionally seen late in the evening, or early in the morning, peering out through some arrow-slit or shot-hole at the chance passenger. i remember getting the whole history of the goblin this day from a sun-burnt herd-boy, whom i found tending his cattle under the shadow of the old castle-wall. i began by asking him whose _apparition_ he thought it was that could continue to haunt a building, the very name of whose last inhabitant had been long since forgotten. "_oh, they're saying_," was the reply, "it's the spirit of the man that was killed on the foundation-stone, just after it was laid, and then built intil the wa' by the masons, that he might _keep_ the castle by coming back again; and _they're saying_ that a' the verra auld houses in the kintra had murderit men builded intil them in that way, and that they have a' o' them their bogle." i recognised in the boy's account of the matter an old and widely-spread tradition, which, whatever may have been its original basis of truth, seems to have so far influenced the buccaneers of the th century, as to have become a reality in their hands. "if time," says sir walter scott, "did not permit the buccaneers to lavish away their plunder in their usual debaucheries, they were wont to hide it, with many superstitious solemnities, in the desert islands and _keys_ which they frequented, and where much treasure, whose lawless owners perished without reclaiming it, is still supposed to be concealed. the most cruel of mankind are often the most superstitious; and those pirates are said to have had recourse to a horrid ritual, in order to secure an unearthly guardian to their treasures. they killed a negro or spaniard, and buried him with the treasure, believing that his spirit would haunt the spot, and terrify away all intruders." there is a figurative peculiarity in the language in which joshua denounced the man who should dare rebuild jericho, that seems to point at some ancient pagan rite of this kind. nor does it seem improbable that a practice which existed in times so little remote as those of the buccaneers, may have first begun in the dark and cruel ages of human sacrifices. "cursed be the man before the lord," said joshua, "that riseth up and buildeth this city of jericho: _he shall lay the foundation thereof in his firstborn, and in his youngest son shall he set up the gates of it_." the large-farm system had been already introduced into the part of the country in which i at this time resided, on the richer and more level lands; but many a gaelic-speaking cottar and small tenant still lived on the neighbouring moors and hill-sides. though highland in their surnames and language, they bore a character considerably different from that of the simpler highlanders of the interior of sutherland, or of a class i had shortly afterwards an opportunity of studying--the highlanders of the western coast of ross-shire. doors were not left unbarred at night in the neighbourhood; and there were wretched hovels among the moors, very zealously watched and guarded indeed. there was much illicit distillation and smuggling at this time among the gaelic-speaking people of the district; and it told upon their character with the usual deteriorating effect. many of the highlanders, too, had wrought as labourers at the caledonian canal, where they had come in contact with south-country workmen, and had brought back with them a confident, loquacious smartness, that, based on a ground-work of ignorance, which it rendered active and obtrusive, had a bizarre and disagreeable effect, and formed but an indifferent substitute for the diffident and taciturn simplicity which it had supplanted. but i have ever found the people of those border districts of the highlands which join on to the low country, or that inhabit districts much traversed by tourists, of a comparatively inferior cast: the finer qualities of the highland character seem easily injured: the hospitality, the simplicity, the unsuspecting honesty, disappear; and we find, instead, a people rapacious, suspicious, and unscrupulous, considerably beneath the lowland average. in all the unopened districts of the remote highlands into which i have penetrated, i have found the people strongly engage my sympathies and affections--much more strongly than in any part of the lowlands; whereas, on the contrary, in the deteriorated districts i have been sensible of an involuntary revulsion of feeling, when in contact with the altered race, of which, among the low-country scotch or the english, i have had no experience. i remember being impressed, in reading, many years ago, one of miss ferrier's novels, with the truth of a stroke that brought out very practically the ready susceptibility of injury manifested by the celtic character. some visitors of condition from the highlands are represented as seeking out in one of our larger towns of the south, a simple highland lad, who had quitted a remote northern district only a few months before; and when they find him, it is as a prisoner in bridewell. towards the end of september, my master, who had wholly failed in overcoming his repugnance to labour as a mere journeyman, succeeded in procuring a piece of work by contract, in a locality about fourteen miles nearer our home than conon-side, and i accompanied him to assist in its completion. our employment in our new scene of labour was of the most disagreeable kind. burns, who must have had a tolerably extensive experience of the evils of hard work, specifies in his "twa dogs" three kinds of labour in especial that give poor "cot-folk" "fash enough." "trowth, caesar, whiles they're fash'd eneugh; a cottar howkin' in a sheugh, wi' dirty stanes biggin' a dyke. baring a quarry, and sic like." all very disagreeable employments, as i also can testify; and our work here unfortunately combined the whole three. we were engaged in rebuilding one of those old-fashioned walls of gentlemen's pleasure-grounds known as "_ha has_," that line the sides of deep ditches, and raise their tops to but the level of the sward; and as the ditch in this special instance was a wet one, and as we had to clear it of the old fallen materials, and to dig it out for our new line of foundation, while at the same time we had to furnish ourselves with additional materials from a neighbouring quarry, we had at once the "baring of the quarry," the "howkin' in the sheugh," and the "biggin' of the dyke wi' dirty stanes," to "fash" us. the last-named employment is by far the most painful and trying. in most kinds of severe labour the skin thickens, and the hand hardens, through a natural provision, to suit the requirements of the task imposed, and yield the necessary protection to the integuments below; but the "dirty stanes" of the dyke-builder, when wet as well as dirty, try the reproductive powers of the cuticle too severely, and wear it off, so that under the rough friction the quick is laid bare. on this occasion, and on at least one other, when engaged in building in a wet season in the western highlands, i had all my fingers oozing blood at once; and those who think that in such circumstances labour protracted throughout a long day can be other than torture, would do well to try. how these poor hands of mine burnt and beat at night at this time, as if an unhappy heart had been stationed in every finger! and what cold chills used to run, sudden as electric shocks, through the feverish frame! my general health, too, had become far from strong. as i had been almost entirely engaged in hewing for the two previous seasons, the dust of the stone, inhaled at every breath, had exerted the usual weakening effects on the lungs--those effects under which the life of the stone-cutter is restricted to about forty-five years; but it was only now, when working day after day with wet feet in a water-logged ditch, that i began to be sensibly informed, by a dull, depressing pain in the chest, and a blood-stained mucoidal substance, expectorated with difficulty, that i had already caught harm from my employment, and that my term of life might fall far short of the average one. i resolved, however, as the last year of my apprenticeship was fast drawing to its close, to complete, at all hazards, my engagement with my master. it had been merely a verbal engagement, and i might have broken it without blame, when, unable to furnish me with work in his character as a master-mason, he had to transfer my labour to another; but i had determined not to break it, all the more doggedly from the circumstance that my uncle james, in a moment of irritation, had said at its commencement that he feared i would no more persist in being a mason than i had done in being a scholar; and so i wrought perseveringly on; and slowly and painfully, rood after rood, the wall grew up under our hands. my poor master, who suffered even more from chopped hands and bleeding fingers than i did, was cross and fretful, and sometimes sought relief in finding fault with his apprentice; but, sobered by my forebodings of an early death, i used to make no reply; and the hasty, ill-tempered expressions in which he gave vent virtually to but his sense of pain and discomfort, were almost always followed by some conciliatory remark. superstition takes a strong hold of the mind in circumstances such as those in which i was at this time placed. one day when on the top of a tall building, part of which we were throwing down to supply us with materials for our work, i raised up a broad slab of red micaceous sandstone, thin as a roofing slate, and exceedingly fragile, and, holding it out at arm's length, dropped it over the wall. i had been worse than usual all that morning, and much depressed; and, ere the slab parted from my hand, i said--looking forward to but a few months of life--i shall break up like that sandstone slab, and perish as little known. but the sandstone slab did not break up: a sudden breeze blew it aslant as it fell; it cleared the rough heap of stones below, where i had anticipated it would have been shivered to fragments; and, lighting on its edge, stuck upright like a miniature obelisk, in the soft green sward beyond. none of the philosophies or the logics would have sanctioned the inference which i immediately drew; but that curious chapter in the history of human belief which treats of signs and omens abounds in such postulates and such conclusions. i at once inferred that recovery awaited me: i was "to live and not die;" and felt lighter, during the few weeks i afterwards toiled at this place, under the cheering influence of the conviction. the tenant of the farm on which our work was situated, and who had been both a great distiller and considerable fanner in his day, had become bankrupt shortly before, and was on the eve of quitting the place, a broken man. and his forlorn circumstances seemed stamped on almost every field and out-house of his farm. the stone fences were ruinous; the hedges gapped by the almost untended cattle; a considerable sprinkling of corn-ears lay rotting on the lea; and here and there an entire sheaf, that had fallen from the "leading-cart" at the close of harvest, might be seen still lying among the stubble, fastened to the earth by the germination of its grains. some of the out-houses were miserable beyond description. there was a square of modern offices, in which the cattle and horses of the farm--appropriated by the landlord, at the time under the law of hypothec--were tolerably well lodged; but the hovel in which three of the farm-servants lived, and in which, for want of a better, my master and i had to cook and sleep, was one of the most miserable tumble-down erections i ever saw inhabited. it had formed part of an ancient set of offices that had been condemned about fourteen years before; but the proprietor of the place becoming insolvent, it had been spared, in lack of a better, to accommodate the servants who wrought on the farm; and it had now become not only a comfortless, but also a very unsafe dwelling. it would have formed no bad subject, with its bulging walls and gapped roof, that showed the bare ribs through the breaches, for the pencil of my friend william koss; but the cow or horse that had no better shelter than that which it afforded could not be regarded as other than indifferently lodged. every heavier shower found its way through the roof in torrents: i could even tell the hour of the night by the stars which passed over the long opening that ran along the ridge from gable to gable; and in stormy evenings i have paused at every ruder blast, in the expectation of hearing the rafters crack and give way over my head. the distiller had introduced upon his farm, on a small scale, what has since been extensively known as the bothy system; and this hovel was the bothy. there were, as i have said, but three farm-servants who lived in it at the time--young, unmarried lads, extremely ignorant, and of gay, reckless dispositions, whose care for their master's interests might be read in the germinating sheaves that lay upon his fields, and who usually spoke of him, when out of his hearing, as "the old sinner." he too evidently cared nothing for them; and they detested him, and regarded the ruin which had overtaken him, and which their own recklessness and indifference to his welfare must have at least assisted to secure, with open satisfaction. "it was ae comfort, anyhow," they said, "that the blastit old sinner, after a' his near-goingness wi' them, was now but a dyvour bankrupt." bad enough certainly; and yet natural enough, and, in a sense, proper enough too. the christian divine would have urged these men to return their master good for evil. cobbett, on the contrary, would have advised them to go out at nights a rick-burning. the better advice will to a certainty not be taken by ninety-nine out of every hundred of our bothy-men; for it is one of the grand evils of the system, that it removes its victims beyond the ennobling influences of religion; and, on the other hand, at least this much may be said for the worse counsel, that the system costs the country every year the price of a great many corn-ricks. the three lads lived chiefly on brose, as the viand at all edible into which their oatmeal could be most readily converted; and never baked or made for themselves a dish of porridge or gruel, apparently to avoid trouble, and that they might be as little as possible in the hated bothy. i always lost sight of them in the evening; but towards midnight their talk frequently awoke me as they were going to bed; and i heard them tell of incidents that had befallen them at the neighbouring farm-houses, or refer to blackguard bits of scandal which they had picked up. sometimes a fourth voice mingled in the dialogue. it was that of a reckless poacher, who used to come in, always long after nightfall, and fling himself down on a lair of straw in a corner of the bothy; and usually ere day broke he was up and away. the grand enjoyment of the three farm-lads--the enjoyment which seemed to counterbalance, with its concentrated delights, the comfortless monotony of weeks--was a rustic ball which took place once every month, and sometimes oftener, at a public-house in the neighbouring village, and at which they used to meet some of the farm-lasses of the locality, and dance and drink whisky till morning. i know not how their money stood such frequent carousals; but they were, i saw, bare of every necessary article of clothing, especially of underclothing and linen; and i learned from their occasional talk about justice-of-peace summonses, that the previous term-day had left in the hands of their shoemakers and drapers unsettled bills. but such matters were taken very lightly: the three lads, if not happy, were at least merry; and the monthly ball, for which they sacrificed so much, furnished not only its hours of pleasure while it lasted, but also a week's talking in anticipation ere it came, and another week's talking over its various incidents after it had passed. and such was my experience of the bothy system in its first beginnings. it has since so greatly increased, that there are now single counties in scotland in which there are from five to eight hundred farm-servants exposed to its deteriorating influences; and the rustic population bids fair in those districts fully to rival that of our large towns in profligacy, and greatly to outrival them in coarseness. were i a statesman, i would, i think, be bold enough to try the efficacy of a tax on bothies. it is long since goldsmith wrote regarding a state of society in which "wealth accumulates and men decay," and since burns looked with his accustomed sagacity on that change for the worse in the character of our rural people which the large-farm system has introduced. "a fertile improved country is west lothian," we find the latter poet remarking, in one of his journals, "but the more elegance and luxury among the farmers, i always observe in equal proportion the rudeness and stupidity of the peasantry. this remark i have made all over the lothians, merse, roxburgh, &c.; and for this, among other reasons, i think that a man of romantic taste--'a man of feeling'--will be better pleased with the poverty but intelligent minds of the peasantry of ayrshire (peasantry they all are, below the justice of peace), than the opulence of a club of merse farmers, when he at the same time considers the vandalism of their plough-folks." the deteriorating effect of the large-farm system, remarked by the poet, is inevitable. it is impossible that the modern farm-servant, in his comparatively irresponsible situation, and with his fixed wages of meagre amount, can be rendered as thoughtful and provident a person as the small farmer of the last age, who, thrown on his own resources, had to cultivate his fields and drive his bargains with his martinmas and whitsunday settlement with the landlord full before him; and who often succeeded in saving money, and in giving a classical education to some promising son or nephew, which enabled the young man to rise to a higher sphere of life. farm-servants, as a class, _must_ be lower in the scale than the old tenant-farmers, who wrought their little farms with their own hands; but it is possible to elevate them far above the degraded level of the bothy; and unless means be taken to check the spread of the ruinous process of brute-making which the system involves, the scottish people will sink, to a certainty, in the agricultural districts, from being one of the most provident, intelligent, and moral in europe, to be one of the most licentious, reckless, and ignorant. candle-light is a luxury in which no one ever thinks of indulging in a barrack; and in a barrack such as ours at this time, riddled with gaps and breaches, and filled with all manner of cold draughts, it was not every night in which a candle would have burnt. and as our fuel, which consisted of sorely decayed wood--the roofing of a dilapidated out-house which we were pulling down--formed but a dull fire, it was with difficulty i could read by its light. by spreading out my book, however, within a foot or so of the embers, i was enabled, though sometimes at the expense of a headache, to prosecute a new tract of reading which had just opened to me, and in which, for a time, i found much amusement. there was a vagabond pedlar who travelled at this time the northern counties, widely known as jack from dover, but whose true name was alexander knox, and who used to affirm that he was of the same family as the great reformer. the pedlar himself was, however, no reformer. once every six weeks or two months he got madly drunk, and not only "perished the pack," as he used to say, but sometimes got into prison to boot. there were, however, some kind relations in the south, who always set him up again; and jack from dover, after a fortnight of misery, used to appear with the ordinary bulk of merchandise at his back, and continue thriving until he again got drunk. he had a turn for buying and reading curious books, which, after mastering their contents, he always sold again; and he learned to bring them, when of a kind which no one else would purchase, to my mother, and recommend them as suitable for me. poor jack was always conscientious in his recommendations. i know not how he contrived to take the exact measure of my tastes in the matter, but suitable for me they invariably were; and as his price rarely exceeded a shilling per volume, and sometimes fell below a sixpence, my mother always purchased, when she could, upon his judgment. i owed to his discrimination my first copy of bacon's "wisdom of the ancients," "done into english by sir arthur gorges," and a book to which i had long after occasion to refer in my geological writings--maillet's "telliamed"--one, of the earlier treatises on the development hypothesis; and he had now procured for me a selection, in one volume, of the poems of gawin douglas and will dunbar, and another collection in a larger volume, of "ancient scottish poems," from the mss. of george bannatyne. i had been previously almost wholly unacquainted with the elder scotch poets. my uncle james had introduced me, at a very early age, to burns and ramsay, and i had found out fergusson and tannahill for myself; but that school of scotch literature which nourished between the reigns of david the second and james the sixth had remained to me, until now, well-nigh a _terra incognita_, and i found no little pleasure in exploring the antique recesses which it opened up. shortly after, i read ramsay's "evergreen," the "king's quair," and the true "actes and deides of ye illuster and vailyeand campioun shyr wilham wallace," not modernized, as in my first copy, but in the tongue in which they had been recited of old by henry the minstrel: i had previously gloated over harbour's bruce; and thus my acquaintance with the old scots poets, if not very profound, became at least so respectable, that not until many years after did i meet with an individual who knew them equally well. the strange picturesque allegories of douglas, and the terse sense and racy humour of dunbar, delighted me much. as i had to con my way slowly amid the difficulties of a language which was no longer that spoken by my country-folk, i felt as if i were creating the sense which i found; it came gradually out like some fossil of the rock, from which i had laboriously to chip away the enveloping matrix; and in hanging admiringly over it, i thought i perceived how it was that some of my old schoolfellows, who were prosecuting their education at college, were always insisting on the great superiority of the old greek and roman writers over the writers of our own country. i could not give them credit for much critical discernment: they were indifferent enough, some of them, to both verse and prose, and hardly knew in what poetry consisted; and yet i believed them to be true to their perceptions when they insisted on what they termed the high excellence of the ancients. with my old schoolfellows, i now said, the process of perusal, when reading an english work of classical standing, is so sudden, compared with the slowness with which they imagine or understand, that they slide over the surface of their author's numbers, or of his periods, without acquiring a due sense of what lies beneath; whereas, in perusing the works of a greek or latin author, they have just to do what i am doing in deciphering the "palice of honour" or the "goldin terge,"--they have to proceed slowly, and to render the language of their author into the language of their own thinking. and so, losing scarce any of his meaning in consequence, and not reflecting on the process through which they have entered into it, they contrast the little which they gain from a hurried perusal of a good english book, with the much which they gain from the very leisurely perusal of a good latin or greek one; and term _the little_ the poverty of modern writers, and _the much_ the fertility of the ancients. such was my theory, and it was at least not an uncharitable one to my acquaintance. i was, however, arrested in the middle of my studies by a day of soaking rain, which so saturated with moisture the decayed spongy wood, our fuel, that, though i succeeded in making with some difficulty such fires of it as sufficed to cook our victuals, it defied my skill to make one by which i could read. at length, however, this dreary season of labour--by far the gloomiest i ever spent--came to a close, and i returned with my master to cromarty about martinmas, our heavy job of work completed, and my term of apprenticeship at a close. chapter xii. "far let me wander down thy craggy shore, with rocks and trees bestrewn, dark loch maree."--small. the restorative powers of a constitution which at this time it took much hard usage to injure, came vigorously into operation on my removal from the wet ditch and the ruinous hovel; and ere the close of winter i had got once more into my ordinary state of robust health. i read, wrote, drew, corresponded with my friend william ross (who had removed to edinburgh), re-examined the eathie lias, and re-explored the eathie burn--a noble old red sandstone ravine, remarkable for the wild picturesqueness of its cliffs and the beauty of its cataracts. i spent, too, many an evening in uncle james's workshop, on better terms with both my uncles than almost ever before--a consequence, in part, of the sober complexion which, as the seasons passed, my mind was gradually assuming, and in part, of the manner in which i had completed my engagement with my master. "act always," said uncle james, "as you have done in this matter. in all your dealings, give your neighbour the _cast of the bauk_--'good measure, heaped up and running over'--and you will not lose by it in the end." i certainly did not lose by faithfully serving out my term of apprenticeship. it is not uninstructive to observe how strangely the public are led at times to attach paramount importance to what is in reality only subordinately important, and to pass over the really paramount without thought or notice. the destiny in life of the skilled mechanic is much more influenced, for instance, by his second education--that of his apprenticeship--than by his first--that of the school; and yet it is to the education of the school that the importance is generally regarded as attaching, and we never hear of the other. the careless, incompetent scholar has many opportunities of recovering himself; the careless, incompetent apprentice, who either fails to serve out his regular time, or who, though he fulfils his term, is discharged an inferior workman, has very few; and further, nothing can be more certain than that inferiority as a workman bears much more disastrously on the condition of the mechanic than inferiority as a scholar. unable to maintain his place among brother journeymen, or to render himself worthy of the average wages of his craft, the ill-taught mechanic falls out of regular employment, subsists precariously for a time on occasional jobs, and either, forming idle habits, becomes a vagabond _tramper_, or, getting into the toils of some rapacious task-master, becomes an enslaved _sweater_. for one workman injured by neglect of his school-education, there are scores ruined by neglect of their apprenticeship-education. three-fourths of the distress of the country's mechanics (of course not reckoning that of the unhappy class who have to compete with machinery), and nine-tenths of their vagabondism, will be found restricted to inferior workmen, who, like hogarth's "careless apprentice," neglected the opportunities of their second term of education. the sagacious painter had a truer insight into this matter than most of our modern educationists. my friend of the doocot cave had been serving a short apprenticeship to a grocer in london during the latter years in which i had been working out mine as a stone-mason in the north country; and i now learned that he had just returned to his native place, with the intention of setting up in business for himself. to those who move in the upper walks, the superiority in status of the village shop-keeper over the journeyman mason may not be very perceptible; but, surveyed from the lower levels of society, it is quite considerable enough to be seen; even gulliver could determine that the emperor of lilliput was taller by almost the breadth of a nail than any of his court; and, though extremely desirous of renewing my acquaintanceship with my old friend, i was sensible enough of his advantage over me in point of position, to feel that the necessary advances should be made on his part, not on mine. i, however, threw myself in his way, though after a manner so fastidiously proud and jealous, that even yet, every time the recollection crosses me, it provokes me to a smile. on learning that he was engaged at the quay in superintending the landing of some goods, for, i suppose, his future shop, i assumed the leathern apron, which i had thrown aside for the winter at martinmas, and stalked past him in my working dress--a veritable operative mason--eyeing him steadfastly as i passed. he looked at me for a moment; and then, without sign of recognition, turned indifferently away. i failed taking into account that he had never seen me girt with a leathern apron before--that, since we had last parted, i had grown more than half a foot--and that a young man of nearly five feet eleven inches, with an incipient whisker palpably visible on his cheek, might be a different-looking sort of person from a smooth-chinned stripling of little more than five feet three. and certainly my friend, as i learned from him nearly three years after, failed on this occasion to recognise me. but believing that he did, and that he did not choose to reckon among his friends a humble working man, i returned to my home very sad, and, i am afraid, not a little angry; and, locking up the supposed slight in my breast, as of too delicate a nature to be communicated to any one, for more than two years from this time i did not again cross his path. i was now my own master, and commenced work as a journeyman in behalf of one of my maternal aunts--the aunt who had gone so many years before to live with her aged relative, the cousin of my father, and the mother of his first wife. aunt jenny had resided for many years after this time with an aged widow lady, who had lived apart in quiet gentility on very small means; and now that she was dead, my aunt saw her vocation gone, and wished that she too could live apart, a life of humble independency, supporting herself by her spinning-wheel, and by now and then knitting a stocking. she feared, however, to encounter the formidable drain on her means of a half-yearly room-rent; and, as there was a little bit of ground at the head of the strip of garden left me by my father, which bordered on a road that, communicating between town and country, bore, as is common in the north of scotland, the french name of the _pays_, it occurred to me that i might try my hand, as a skilled mechanic, in erecting upon it a cottage for aunt jenny. masons have, of course, more in their power in the way of house-building than any other class of mechanics. it was necessary, however, that there should be money provided for the purchase of wood for the roof, and for the carting of the necessary stones and mortar; and i had none. but aunt jenny had saved a few pounds, and a very few proved sufficient; and so i built a cottage in the _pays_, of a single room and a closet, as my first job, which, if not very elegant, or of large accommodation, came fully up to aunt jenny's ideas of comfort, and which, for at least a quarter of a century, has served her as a home. it was completed before whitsunday, and i then deliberated on setting myself to seek after employment of a more remunerative kind, with just a little of the feeling to which we owe one of the best-known elegiac poems in the language--the "man was made to mourn" of burns. "there is nothing that gives me a more mortifying picture of human life," said the poet, "than a man seeking work." the required work, however, came direct in my way without solicitation, and exactly at the proper time. i was engaged to assist in hewing a gothic gateway among the woods of my old haunt, conon-side; and was then despatched, when the work was on the eve of being finished, to provide materials for building a house on the western coast of ross-shire. my new master had found me engaged in the previous season, amid the wild turmoil of the barrack, in studying practical geometry, and had glanced approvingly over a series of architectural drawings which i had just completed; and he now sought me out in consequence, and placed me in charge of a small party which he despatched in advance of his other workmen, and which i was instructed to increase, by employing a labourer or two on arriving at the scene of our future employment. we were to be accompanied by a carter from a neighbouring town; and on the morning fixed for the commencement of our journey, his cart and horse were early at conon-side, to carry across the country the tools required at our new job; but of himself we saw no trace; and about ten o'clock we set off without him. ascertaining, however, when about two miles on our way, that we had left behind us a lever useful in the setting of large stones, i bade my companion wait for me at the village of contin, where we expected meeting the carter; and, returning for the tool, i quitted the high road on finding it, and, to save time, and avoid a detour of about three miles, struck across the country direct on the village. my way was, however, a very rough one; and in coming upon the conon, which it was necessary i should ford--for by avoiding the detour i had missed the bridge--i found it tolerably heavy in flood. save for the iron lever which i carried, i would have selected, as my point of crossing, one of the still deep pools, as much safer to a vigorous swimmer than any of the apparent fords, with their powerful currents, whirling eddies, and rough bottoms. but though the heroes of antiquity--men such as julius cæesar and horatius cocles--could swim across rivers and seas in heavy armour, the specific gravity of the human subject in these latter ages of the world forbids such feats; and, concluding that i had not levity enough in my framework to float across the lever, i selected, with some hesitation, one of the better-looking fords, and, with my trousers dangling from the iron beam on my shoulder, entered the river. such was the arrowy swiftness of the current, however, that the water had scarce reached my middle when it began to hollow out the stones and gravel from under my feet, and to bear me down per force in a slanting direction. there was a foaming rapid just at hand; and immediately beyond, a deep, dark pool, in which the chafed current whirled around, as if exhausting the wrath aroused by its recent treatment among rocks and stones, ere recovering its ordinary temper; and had i lost footing, or been carried a little further down, i know not how it might have fared with me in the wild foaming descent that lay between the ford and the pool. curiously enough, however, the one idea which, in the excitement of the moment, filled my mind, was an intensely ludicrous one. i would, of course, lose not only the lever in the torrent, but my trousers also; and how was i ever to get home without them? where, in the name of wonder, should i get a kilt to borrow? i have oftener than once experienced this strange sensation of the ludicrous in circumstances with which a different feeling would have harmonized better. byron represents it as rising in extreme grief: it is, however, i suspect, greatly more common in extreme danger; and all the instances which the poet himself gives in his note--sir thomas more on the scaffold, anne boleyn in the tower, and those victims of the french revolution "with whom it became a fashion to leave some _mot_ as a legacy"--were all jokers rather in circumstances of desperate and hopeless peril than of sorrow. it is, however, in danger, us certainly as in grief, a joyless sort of mirth. "that playfulness of sorrow ne'er beguiles; it smiles in bitterness: but still it smiles, and sometimes with the wisest and the best. till even the scaffold echoes with their jest." the feeling, however, though an inharmoniously toned, is not a weakening one. i laughed in the stream, but i did not yield to it; and, making a violent effort, when just on the edge of the rapid, i got into stiller water, and succeeded in making my way to the opposite bank, drenched to the arm-pits. it was in nearly the same reach of the conon that my poor friend the maniac of ord lost her life a few days after. i found my companion in charge of the cart with our tools, baiting at an inn a little beyond contin; but there was no sign of the carter; and we were informed by the innkeeper, to whom he was well known, that we might have to wait for him all day, and perhaps not see him at night. click-clack--a name expressive of the carter's fluency as a talker, by which he was oftener designated than by the one in the parish register--might no doubt have purposed in the morning joining us at an early hour, but that was when he was sober; and what his intention might be now, said the innkeeper, when in all probability he was drunk, no living man could say. this was rather startling intelligence to men who had a long journey through a rough country before them; and my comrade--a lad a year or two older than myself, but still an apprentice--added to my dismay by telling me he had been sure from the first there was something wrong with click-clack, and that his master had secured his services, not from choice, but simply because, having thoughtlessly become surety for him at a sale for the price of a horse, and being left to pay for the animal, he had now employed him, in the hope of getting himself reimbursed. i resolved, however, on waiting for the carter until the last moment after which it would be possible for us to reach our ultimate stage without perilously encroaching on the night; and, taking it for granted that he would not very soon join us, i set out for a neighbouring hill, which commands an extensive view, to take note of the main features of a district with which i had formed, during the two previous years, not a few interesting associations, and to dry my wetted clothes in the breeze and the sun. the old tower of fairburn formed one of the most striking objects in the prospect; and the eye expatiated beyond from where the gneiss region begins, on a tract of broken hill and brown moor, uncheered by a single green field or human dwelling. there are traditions that, in their very peculiarity, and remoteness from the tract of ordinary intention, give evidence of their truth; and i now called up a tradition, which i owed to my friend the maniac, respecting the manner in which the mackenzies of fairburn and the chisholms of strathglass had divided this barren tract between them. it had lain, from the first settlement of the country, an unappropriated waste, and neither proprietor could tell where his own lands terminated, or those of his neighbour began; but finding that the want of a proper line of demarcation led to quarrels between their herdsmen when baiting in their summer shielings with their cattle, they agreed to have the tract divided. the age of land-surveyors had not yet come; but, selecting two old women of seventy-five, they sent them out at the same hour, to meet among the hills, the one from fairburn tower, the other from erchless castle, after first binding themselves to accept their place of meeting as the point at which to set up the boundary-stone of the two properties. the women, attended by a bevy of competent witnesses, journeyed as if for life and death; but the fairburn woman, who was the laird's foster-mother, either more zealous or more active than the chisholm one, travelled nearly two miles for her one; and when they came in sight of each other in the waste, it was far from the fields of fairburn, and comparatively at no great distance from those of the chisholm. it is not easy knowing why they should have regarded one another in the light of enemies; but at a mile's distance their flagging pace quickened into a run, and, meeting at a narrow rivulet, they would fain have fought; but lacking, in their utter exhaustion, strength for fighting and breath for scolding, they could only seat themselves on the opposite banks, and _girn_ at one another across the stream. george cruikshank has had at times worse subjects for his pencil. it is, i believe, landor, in one of his "imaginary conversations," who makes a highland laird inform adam smith that, desirous to ascertain, in some sort of conceivable degree, the size of his property, he had placed a line of pipers around it, each at such a distance from his nearest neighbour that he could barely catch the sound of his bagpipe; and that from the number of pipers required he was able to form an approximate estimate of the extent of his estate. and here, in a highland tradition, genuine at least as such, are we introduced to an expedient of the kind scarce less ludicrous or inadequate than that which landor must, in one of his humorous moods, have merely imagined. i returned to the inn at the hour from which, as i have said, it would be possible for us, and not more than possible, to complete our day's journey; and finding, as i had anticipated, no trace of click-clack, we set off without him. our way led us through long moory straths, with here and there a blue lake and birch wood, and here and there a group of dingy cottages and of irregular fields; but the general scenery was that of the prevailing schistose gneiss of the scotch highlands, in which rounded confluent hills stand up over long-withdrawing valleys, and imposing rather from its bare and lonely expansiveness, than from aught bold or striking in its features. the district had been opened up only a few seasons previous by the parliamentary road over which we travelled, and was at that time little known to the tourist; and the thirty years which have since passed have in some respects considerably changed it, as they have done the highlands generally. most of the cottages, when i last journeyed the way, were represented by but broken ruins, and the fields by mossy patches that remained green amid the waste. i marked at one spot an extraordinary group of oak-trees, in the last stage of decay, which would have attracted notice from their great bulk and size in even the forests of england. the largest of the group lay rotting upon the ground--a black, doddered shell, fully six feet in diameter, but hollow as a tar-barrel; while the others, some four or five in number, stood up around it, totally divested of all their larger boughs, but green with leaves, that, from the minuteness of the twigs on which they grew, wrapped them around like close-fitting mantles. their period of "tree-ship"--to borrow a phrase from cowper--must have extended far into the obscure past of highland history--to a time, i doubt not, when not a few of the adjacent peat mosses still lived as forests, and when some of the neighbouring clans--frasers, bissets, and chisholms--had, at least under the existing names (french and saxon in their derivation), not yet begun to be. ere we reached the solitary inn of auchen-nasheen--a true highland clachan of the ancient type, the night had fallen dark and stormy for a night in june; and a grey mist which had been descending for hours along the hills--blotting off their brown summits bit by bit, as an artist might his pencilled hills with a piece of india rubber, but which, methodical in its encroachments, had preserved in its advances a perfect horizontality of line--had broken into a heavy, continuous rain. as, however, the fair weather had lasted us till we were within a mile of our journey's end, we were only partially wet on our arrival, and soon succeeded in drying ourselves in front of a noble turf fire. my comrade would fain have solaced himself, after our weary journey, with something nice. he held that a highland inn should be able to furnish at least a bit of mutton-ham or a cut of dried salmon, and ordered a few slices, first of ham, and then of salmon; but his orders served merely to perplex the landlord and his wife, whose stores seemed to consist of only oatmeal and whisky; and, coming down in his expectations and demands, and intimating that he was very hungry, and that anything edible would do, we heard the landlady inform, with evident satisfaction, a red-armed wench, dressed in blue plaiding, that "the lads would take porridge." the porridge was accordingly prepared; and, when engaged in discussing this familiar viand, a little before midnight--for we had arrived late--a tall highlander entered the inn, dropping like a mill-wheel. he was charged, he said, with messages to the landlord, and to two mason lads in the inn, from a forlorn carter with whom he had travelled about twenty miles, but who, knocked up by the "drap drink" and a pair of bad shoes, had been compelled to shelter for the night in a cottage about seven miles short of auchen-nasheen. the carter's message to the landlord was simply to the effect that the two mason lads having stolen his horse and cart, he instructed him to detain his property for him until he himself should come up in the morning. as for his message to the lads, said the highlander, "it was no meikle worth gaun o'er again; but if we liked to buckle on a' the gaelic curses to a' the english ones, it would be something like that." we were awakened next morning by a tremendous hubbub in the adjoining apartment. "it is click-clack the carter," said my comrade: "oh, what shall we do?" we leaped up; and getting into our clothes in doubly-quick time, set ourselves to reconnoitre through the crannies of a deal partition, and saw the carter standing in the middle of the next room, storming furiously, and the landlord, a smooth-spoken, little old man, striving hard to conciliate him. click-clack was a rough-looking fellow, turned of forty, of about five feet ten, with a black unshaven beard, like a shoe-brush stuck under his nose, which was red as a coal, and attired in a sadly-breached suit of aberdeen grey, topped by a brimless hat, that had been borrowed, apparently, from some obliging scare-crow. i measured him in person and expression; and, deeming myself his match, even unassisted by my comrade, on whose discretion i could calculate with more certainty than on his valour, i entered the apartment, and taxed him with gross dereliction of duty. he had left us to drive his horse and cart for a whole day, and had broken, for the sake of his wretched indulgence in the public-house, his engagement with our master; and i would report him to a certainty. the carter turned upon me with the fierceness of a wild beast; but, first catching his eye, as i would that of a maniac, i set my face very near his, and he calmed down in a moment. he could not help being late, he said: he had reached the inn at contin not an hour after we had left it; and it was really very hard to have to travel a long day's journey in such bad shoes. we accepted his apology; and, ordering the landlord to bring in half a mutchkin of whisky, the storm blew by. the morning, like the previous night, had been thick and rainy; but it gradually cleared up as the day rose; and after breakfast we set out together along a broken footpath, never before traversed by horse and cart. we passed a solitary lake, on whose shores the only human dwelling was a dark turf shieling, at which, however, click-clack ascertained there was whisky to be sold; and then entered upon a tract of scenery wholly different in its composition and character from that through which our journey had previously lain. there runs along the west coast of scotland, from the island of rum to the immediate neighbourhood of cape wrath, a formation, laid down by macculloch, in his geological map of the kingdom, as old red sandstone, but which underlies formations deemed primary--two of these of quartz rock, and a third of that unfossiliferous limestone in which the huge cave of smoo is hollowed, and to which the assynt marbles belong. the system, which, taken as a whole--quartz-rock, lime, and sandstone--corresponds bed for bed with the lower old red of the east coast, and is probably a highly metamorphic example of that great deposit, exhibits its fullest development in assynt, where all its four component beds are present. in the tract on which we now entered, it presents only two of these--the lower quartz-rock, and the underlying red sandstone; but wherever any of its members appear, they present unique features--marks of enormous denudation, and a bold style of landscape altogether its own; and, in now entering upon it for the first time, i was much impressed by its extraordinary character. loch maree, one of the wildest of our highland lakes, and at this time scarce at all known to the tourist, owes to it all that is peculiar in its appearance--its tall pyramidal quartz mountains, that rise at one stride, steep, and well-nigh as naked as the old pyramids, from nearly the level of the sea, to heights on which at midsummer the snows of winter gleam white in streaks and patches; and a picturesque sandstone tract of precipitous hills, which flanks its western shore, and bore at this period the remains of one of the old pine forests. a continuous wall of gneiss mountains, that runs along the eastern side of the lake, sinks sheer into its brown depths, save at one point, where a level tract, half-encircled by precipices, is occupied by fields and copsewood, and bears in the midst a white mansion-house; the blue expanse of the lake greatly broadens in its lower reaches; and a group of partially submerged hillocks, that resemble the forest-covered ones on its western shores, but are of lower altitude, rise over its waters, and form a miniature archipelago, grey with lichened stone, and bosky with birch and hazel. finding at the head of the loch that no horse and cart had ever forced their way along its sides, we had to hire a boat for the transport of at least cart and baggage; and when the boatmen were getting ready for the voyage, which was, with the characteristic dilatoriness of the district, a work of hours, we baited at the clachan of _kinlochewe_--a humble highland inn, like that in which we had passed the night. the name--that of an old farm which stretches out along the _head_ or upper end of loch maree--has a remarkable etymology: it means simply the head of _loch ewe_--the salt-water loch into which the waters of loch maree empty themselves by a river little more than a mile in length, and whose present _head_ is some sixteen or twenty miles distant from the farm which bears its name. ere that last elevation of the land, however, to which our country owes the level marginal strip that stretches between the present coast-line and the ancient one, the sea must have found its way to the old farm. loch maree (mary's loch), a name evidently of mediæval origin, would then have existed as a prolongation of the marine loch ewe, and _kinlochewe_ would have actually been what the compound words signify--the head of loch ewe. there seems to be reason for holding that, ere the latest elevation of the land took place in our island, it had received its first human inhabitants--rude savages, who employed tools and weapons of stone, and fashioned canoes out of single logs of wood. are we to accept etymologies such as the instanced one--and there are several such in the highlands--as good, in evidence that these aboriginal savages were of the celtic race, and that gaelic was spoken in scotland at a time when its strips of grassy links, and the sites of many of its seaport towns, such as leith, greenock, musselburgh, and cromarty, existed as oozy sea-beaches, covered twice every day by the waters of the ocean? it was a delightful evening--still, breathless, clear--as we swept slowly across the broad breast of loch maree; and the red light of the sinking sun fell on many a sweet wild recess, amid the labyrinth of islands purple with heath, and overhung by the birch and mountain-ash; or slanted along the broken glades of the ancient forest; or lighted up into a blush the pale stony faces of the tall pyramidal hills. a boat bearing a wedding party was crossing the lake to the white house on the opposite side, and a piper stationed in the bows, was discoursing sweet music, that, softened by distance, and caught up by the echoes of the rocks, resembled no strain i had ever heard from the bagpipe before. even the boatmen rested on their oars, and i had just enough of gaelic to know that they were remarking how very beautiful it was. "i wish," said my comrade, "you understood these men: they have a great many curious stories about the loch, that i am sure you would like. see you that large island? it is island-maree. there is, they tell me, an old burying-ground on it, in which the danes used to bury long ages ago, and whose ancient tomb-stones no man can read. and yon other island beside it is famous as the place in which the _good_ people meet every year to make submission to their queen. there is, they say, a little loch in the island, and another little island in the loch; and it is under a tree on that inner island that the queen sits and gathers kain for the evil one. they tell me that, for certain, the fairies have not left this part of the country yet." we landed, a little after sunset, at the point from which our road led across the hills to the sea-side, but found that the carter had not yet come up; and at length, despairing of his appearance, and unable to carry off his cart and the luggage with us, as we had succeeded in bringing off cart, horse, and luggage on the previous day, we were preparing to take up our night's lodging under the shelter of an overhanging crag, when we heard him coming soliloquizing through the wood, in a manner worthy of his name, as if he were not one, but twenty carters. "what a perfect shame of a country!" he exclaimed--"perfect shame! road for a horse, forsooth!--more like a turnpike stair. and not a feed of corn for the poor beast; and not a public-house atween this and kinlochewe; and not a drop of whisky: perfect, perfect shame of a country!" on his coming up in apparently very bad humour, we found him disposed to transfer the shame of the country to our shoulders. what sort of people were we, he asked, to travel in such a land without whisky! whisky, however, there was none to produce: there was no whisky nearer, we told him, than the public-house at the sea-side, where we proposed spending the night; and, of course, the sooner we got there the better. and after assisting him to harness his horse, we set off in the darkening twilight, amid the hills. rough grey rocks, and little blue lochans, edged with flags, and mottled in their season with water-lilies, glimmered dim and uncertain in the imperfect light as we passed; but ere we reached the inn of flowerdale in gairloch, every object stood out clear, though cold, in the increscent light of morning; and a few light streaks of cloud, poised in the east over the unrisen sun, were gradually exchanging their gleam of pale bronze for a deep flush of mingled blood and fire. after the refreshment of a few hours' sleep and a tolerable breakfast, we set out for the scene of our labours, which lay on the sea-shore, about two miles further to the north and west; and were shown an out-house--one of a square of dilapidated offices--which we might fit up, we were told, for our barrack. the building had been originally what is known on the north-western coast of scotland, with its ever-weeping climate, as a hay-barn; but it was now merely a roof-covered tank of green stagnant water, about three-quarters of a foot in depth, which had oozed through the walls from an over-gorged pond in the adjacent court, that in a tract of recent rains had overflowed its banks, and not yet subsided. our new house did look exceedingly like a beaver-dam, with this disadvantageous difference, that no expedient of diving could bring us to better chambers on the other side of the wall. my comrade, setting himself to sound the abyss with his stick, sung out in sailor style, "three feet water in the hold." click-clack broke into a rage: "that a dwelling for human creatures!" he said. "if i was to put my horse intil't, poor beast! the very hoofs would rot off him in less than a week. are we eels or puddocks, that we are sent to live in a loch?" marking, however, a narrow portion of the ridge which dammed up the waters of the neighbouring pool whence our domicile derived its supply, i set myself to cut it across, and had soon the satisfaction of seeing the general surface lowered fully a foot, and the floor of our future dwelling laid bare. click-clack, gathering courage as he saw the waters ebbing away, seized a shovel, and soon showed us the value of his many years' practice in the labours of the stable; and then, despatching him for a few cart-loads of a dry shell-sand from the shore, which i had marked by the way as suitable for mixing with our lime, we had soon for our tank of green water a fine white floor. "man wants but little here below," especially in a mason's barrack. there were two square openings in the apartment, neither of them furnished with frame or glass; but the one we filled up with stone, and an old unglazed frame, which, with the assistance of a base and border of turf, i succeeded in fitting into the other, gave at least an air of respectability to the place. boulder stones, capped with pieces of mossy turf, served us for seats; and we had soon a comfortable peat fire blazing against the gable; but we were still sadly in want of a bed: the fundamental damp of the floor was, we saw, fast gaining on the sand; and it would be neither comfortable nor safe to spread our dried grass and blankets over _it_. my comrade went out to see whether the place did not furnish materials enough of any kind to make a bedstead, and soon returned in triumph, dragging after him a pair of harrows which he placed side by side in a snug corner beside the fire, with of course the teeth downwards. a good catholic, prepared to win heaven for himself by a judicious use of sharp points, might have preferred having them turned the other way; but my comrade was an enlightened protestant; and besides, like goldsmith's sailor, he loved to lie soft. the second piece of luck was mine. i found lying unclaimed in the yard an old barn-door, which a recent gale had blown from off its hinges; and by placing it above the harrows, and driving a row of stakes around it into the floor, to keep the outer sleeper from rolling off--for the wall served to secure the position of the inner one--we succeeded in constructing, by our joint efforts, a luxurious bed. there was but one serious drawback on its comforts: the roof overhead was bad, and there was an obstinate drop, that used, during every shower which fell in the season of sleep, to make a dead set at my face, and try me at times with the water torture of the old story, mayhap half a dozen times in the course of a single night. our barrack fairly fitted up, i set out with my comrade, whose knowledge of gaelic enabled him to act as my interpreter, to a neighbouring group of cottages, to secure a labourer for the work of the morrow. the evening was now beginning to darken; but there was still light enough to show me that the little fields i passed through on my way resembled very much those of liliput, as described by gulliver. they were, however, though equally small, greatly more irregular, and had peculiarities, too, altogether their own. the land had originally been stony; and as it showed, according to the highland phrase, its "bare bones through its skin"--large bosses of the rock beneath coming here and there to the surface--the highlanders had gathered the stones in great pyramidal heaps on the bare bosses; and so very numerous were these in some of the fields, that they looked as if some malignant sorcerer had, in the time of harvest, converted all their shocks into stone. on approaching the cottage of our future labourer, i was attracted by a door of very peculiar construction that lay against the wall. it had been brought from the ancient pine forest on the western bank of loch maree, and was formed of the roots of trees so curiously interlaced by nature, that when cut out of the soil, which it had covered over like a piece of network, it remained firmly together, and now formed a door which the mere imitator of the rustic might in vain attempt to rival. we entered the cottage, and plunging downwards two feet or so, found ourselves upon the dunghill of the establishment, which in this part of the country usually occupied at the time an ante-chamber which corresponded to that occupied by the cattle a few years earlier, in the midland districts of sutherland. groping in this foul outer chamber through a stifling atmosphere of smoke, we came to an inner door raised to the level of the soil outside, through which a red umbry gleam escaped into the darkness; and, climbing into the inner apartment, we found ourselves in the presence of the inmates of the mansion. the fire, as in the cottage of my sutherlandshire relative, was placed in the middle of the floor: the master of the mansion, a red-haired, strongly-built highlander, of the middle size and age, with his son, a boy of twelve, sat on the one side; his wife, who, though not much turned of thirty, had the haggard, drooping cheeks, hollow eyes, and pale, sallow complexion of old age, sat on the other. we broke our business to the highlander through my companion--for, save a few words caught up at school by the boy, there was no english in the household--and found him disposed to entertain it favourably. a large pot of potatoes hung suspended over the fire, under a dense ceiling of smoke; and he hospitably invited us to wait supper, which, as our dinner had consisted of but a piece of dry oaten cake, we willingly did. as the conversation went on, i became conscious that it turned upon myself, and that i was an object of profound commiseration to the inmates of the cottage. "what," i inquired of my companion, "are these kind people pitying me so very much for?" "for your want of gaelic, to be sure. how can a man get on in the world that wants gaelic?" "but do not they themselves," i asked, "want english?" "o yes," he said, "but what does that signify? what is the use of english in gairloch?" the potatoes, with a little ground salt, and much unbroken hunger as sauce, ate remarkably well. our host regretted that he had no fish to offer us; but a tract of rough weather had kept him from sea, and he had just exhausted his previous supply; and as for bread, he had used up the last of his grain crop a little after christmas, and had been living, with his family, on potatoes, with fish when he could get them, ever since. thirty years have now passed since i shared in the highlander's evening meal, and during the first twenty of these, the use of the potatoe--unknown in the highlands a century before--greatly increased. i have been told by my maternal grandfather, that about the year , when he was a boy of about eight or nine years of age, the head-gardener at balnagown castle used, in his occasional visits to cromarty, to bring him in his pocket, as great rarities, some three or four potatoes; and that it was not until some fifteen or twenty years after this time that he saw potatoes reared in fields in any part of the northern highlands. but, once fairly employed as food, every season saw a greater breadth of them laid down. in the north-western highlands, in especial, the use of these roots increased from the year to the year nearly a hundredfold, and came at length to form, as in ireland, not merely the staple, but in some localities almost the only food of the people; and when destroyed by disease in the latter year, famine immediately ensued in both ireland and the highlands. a writer in the _witness_, whose letter had the effect of bringing that respectable paper under the eye of mr. punch, represented the irish famine as a direct judgment on the maynooth endowment; while another writer, a member of the peace association--whose letter did not find its way into the _witness_, though it reached the editor--challenged the decision on the ground that the scotch highlanders, who were greatly opposed to maynooth, suffered from the infliction nearly as much as the irish themselves, and that the offence punished must have been surely some one of which both highlanders and irish had been guilty in common. _he_, however, had found out, he said, what the crime visited actually was. both the irish and highland famines were judgments upon the people for their great homicidal efficiency as soldiers in the wars of the empire--an efficiency which, as he truly remarked, was almost equally characteristic of both nations. for my own part, i have been unable hitherto to see the steps which conduct to such profound conclusions; and am content simply to hold, that the superintending providence who communicated to man a calculating, foreseeing nature, does occasionally get angry with him, and inflict judgments upon him, when, instead of exercising his faculties, he sinks to a level lower than his own, and becomes content, like some of the inferior animals, to live on a single root. there are two periods favourable to observation--an early and a late one. a fresh eye detects external traits and peculiarities among a people, seen for the first time, which disappear as they become familiar; but it is not until after repeated opportunities of study, and a prolonged acquaintanceship, that internal characteristics and conditions begin to be rightly known. during the first fortnight of my residence in this remote district, i was more impressed than at a later stage by certain peculiarities of manner and appearance in the inhabitants. dr. johnson remarked that he found fewer very tall or very short men among the people of the hebrides than in england: i was now struck by a similar mediocrity of size among the highlanders of western ross; five-sixths of the grown men seemed to average between five feet seven and five feet nine inches in height, and either tall or short men i found comparatively rare. the highlanders of the eastern coast were, on the contrary, at that period, mayhap still, very various of stature--some of them exceedingly diminutive, others of great bulk and height; and, as might be seen in the congregations of the parish churches removed by but a few miles, there were marked differences in this respect between the people of contiguous districts--certain tracts of plain or valley producing larger races than others. i was inclined to believe at the time that the middle-sized highlanders of the west coast were a less mixed race than the unequally-sized highlanders of the east: i at least found corresponding inequalities among the higher-born highland families, that, as shown by their genealogies, blended the norman and saxon with the celtic blood; and as the unequally-sized highland race bordered on that scandinavian one which fringes the greater part of the eastern coast of scotland, i inferred that there had been a similar blending of blood among _them_. i have since seen, in gustav kombst's ethnographic map of the british islands, the difference which i at this time but inferred, indicated by a different shade of colour, and a different name. the highlanders of the east coast kombst terms "scandinavian-gaelic;" those of the west, "gaelic-scandinavian-gaelic,"--names indicative, of course, of the proportions in which he holds that they possess the celtic blood. disparity of bulk and size appears to be one of the consequences of a mixture of races; nor does the induced inequality seem restricted to the physical framework. minds of large calibre, and possessed of the kingly faculty, come first into view, in our history, among the fused tribes, just as of old it was the mixed marriages that first produced the giants. the difference in size which i remarked in particular districts of the scandinavian-gaelic region, separated, in some instances, by but a ridge of hills or an expanse of moor, must have been a result of the old clan divisions, and is said to have marked the clans themselves very strongly. some of them were of a greatly more robust, and some of a slimmer type, than others. i was struck by another peculiarity in the west coast highlanders. i found the men in general greatly better-looking than the women, and that in middle life they bore their years much more lightly. the females seemed old and haggard at a period when the males were still comparatively fresh and robust. i am not sure whether the remark may not in some degree apply to highlanders generally. the "rugged form" and "harsher features," which, according to sir walter, "mark the mountain band," accord worse with the female than with the male countenance and figure. but i at least found this discrepancy in the appearance of the sexes greatly more marked on the west than on the eastern coast; and saw only too much reason to conclude that it was owing in great part to the disproportionately large share of crushing labour laid, in the district, in accordance with the practice of a barbarous time, on the weaker frame of the female. there is, however, a style of female loveliness occasionally though rarely exemplified in the highlands, which far transcends the saxon or scandinavian type. it is manifested usually in extreme youth--at least between the fourteenth and eighteenth year; and its effect we find happily indicated by wordsworth--who seems to have met with a characteristic specimen--in his lines to a highland girl. he describes her as possessing as her "dower," "a very _shower_ of beauty." further, however, he describes her as very young. "twice seven consenting years had shed their utmost bounty on her head." i was, besides, struck at this time by finding, that while almost all the young lads under twenty with whom i came in contact had at least a smattering of english, i found only a single highlander turned of forty with whom i could exchange a word. the exceptional highlander was, however, a curiosity in his way. he seemed to have a natural turn for acquiring languages, and had derived his english, not from conversation, but, in the midst of a gaelic-speaking people, from the study of the scriptures in our common english version. his application of bible language to ordinary subjects told at times with rather ludicrous effect. upon inquiring of him, on one occasion, regarding a young man whom he wished to employ as an extra labourer, he described him in exactly the words in which david is described in the chapter that records the combat with goliath, as "but a youth, and ruddy, and of a fair countenance;" and on asking where he thought we could get a few loads of water-rolled pebbles for causewaying a floor, he directed us to the bed of a neighbouring rivulet, where we might "choose us," he said, "smooth stones out of the brook." he spoke with great deliberation, translating evidently his gaelic thinking, as he went on, into scriptural english. chapter xiii. "a man of glee with hair of glittering grey, as blythe a man as you could see on a spring holiday."--wordsworth. there existed at this time no geological map of scotland. macculloch's did not appear until about six or seven years after (in or ), and sedgwick and murchison's interesting sketch of the northern formations[ ] not until at least five years after ( ). and so, on setting out on the morning after that of my arrival, to provide stones for our future erection, i found myself in a _terra incognita_, new to the quarrier, and unknown to the geologist. most of the stratified primary rocks make but indifferent building materials; and in the immediate neighbourhood of our work i could find only one of the worst of the class--the schistose gneiss. on consulting, however, the scenery of the district, i marked that at a certain point both shores of the open sea-loch on whose margin we were situated suddenly changed their character. the abrupt rugged hills of gneiss that, viewed from an eminence, resembled a tumbling sea, suddenly sank into low brown promontories, unbroken by ravines, and whose eminences were mere flat swellings; and in the hope of finding some change of formation coincident with the change of scenery, i set out with my comrade for the nearest point at which the broken outline passed into the rectilinear or merely undulatory one. but though i did expect a change, it was not without some degree of surprise that, immediately after passing the point of junction, i found myself in a district of red sandstone. it was a hard, compact, dark-coloured stone, but dressed readily to pick and hammer, and made excellent corner-stones and ashlar; and it would have furnished us with even hewn work for our building, had not our employer, unacquainted, like every one else at the time, with the mineral capabilities of the locality, brought his hewing stone in a sloop, at no small expense, through the caledonian canal, from one of the quarries of moray--a circuitous voyage of more than two hundred miles. immediately beside where we opened our quarry, there was a little solitary shieling: it was well-nigh such an edifice as i used to erect when a boy--some eight or ten feet in length, and of so humble an altitude, that, when standing erect in the midst, i could lay my hand on the roof-tree. a heath-bed occupied one of the corners; a few grey embers were smouldering in the middle of the floor; a pot lay beside them, ready for use, half-filled with cockles and razor-fish, the spoils of the morning ebb; and a cog of milk occupied a small shelf that projected from the gable above. such were the contents of the shieling. its only inmate, a lively little old man, sat outside, at once tending a few cows grouped on the moor, and employed in stripping with a pocket-knife, long slender filaments from off a piece of moss fir; and as he wrought and watched, he crooned a gaelic song, not very musically mayhap, but, like the happy song of the humble-bee, there was perfect content in every tone. he had a great many curious questions to ask in his native gaelic, of my comrade, regarding our employment and our employer; and when satisfied, he began, i perceived, like the highlander of the previous evening, to express very profound commiseration for me. "is that man also pitying me?" i asked. "o yes, very much," was the reply: "he does not at all see how you are to live in gairloch without gaelic." i was reminded by the shieling and its happy inmate, of one of my father's experiences, as communicated to me by uncle james. in the course of a protracted kelp voyage among the hebrides, he had landed in his boat, before entering one of the sounds of the long island, to procure a pilot, but found in the fisherman's cottage on which he had directed his course, only the fisherman's wife--a young creature of not more than eighteen--engaged in nursing her child, and singing a gaelic song, in tones expressive of a light heart, till the rocks rang again. a heath bed, a pot of baked clay, of native manufacture, fashioned by the hand, and a heap of fish newly caught, seemed to constitute the only wealth of the cottage; but its mistress was, notwithstanding, one of the happiest of women; and deeply did she commiserate the poor sailors, and earnestly wish for the return of her husband, that he might assist them in their perplexity. the husband at length appeared. "oh," he asked, after the first greeting, "have you any salt?" "plenty," said the master; "and you, i see, from your supply of fresh fish, want it very much; but come, pilot us through the sound, and you shall have as much salt as you require." and so the vessel got a pilot, and the fisherman got salt; but never did my father forget the light-hearted song of the happy mistress of that poor highland cottage. it was one of the palpable characteristics of our scottish highlanders, for at least the first thirty years of the century, that they were contented enough, as a people, to find more to pity than to envy in the condition of their neighbours; and i remember that at this time, and for years after, i used to deem the trait a good one. i have now, however, my doubts on the subject, and am not quite sure whether a content so general as to be national may not, in certain circumstances, be rather a vice than a virtue. it is certainly no virtue when it has the effect of arresting either individuals or peoples in their course of development; and is perilously allied to great suffering, when the men who exemplify it are so thoroughly happy amid the mediocrities of the present, that they fail to make provision for the contingencies of the future. we were joined in about a fortnight by the other workmen from the low country, and i resigned my temporary charge (save that i still retained the time-book in my master's behalf) into the hands of an ancient mason, remarkable over the north of scotland for his skill as an operative, and who, though he was now turned of sixty, was still able to build and hew considerably more than the youngest and most active man in the squad. he was at this time the only survivor of three brothers, all masons, and all not merely first-class workmen, but of a class to which, at least to the north of the grampians, only they themselves belonged, and very considerably in advance of the first. and on the removal of the second of the three brothers to the south of scotland, it was found that, amid the stone-cutters of glasgow, david fraser held relatively the same place that he had done among those of the north. i have been told by mr. kenneth matheson--a gentleman well known as a master-builder in the west of scotland--that in erecting some hanging stairs of polished stone, ornamented in front and at the outer edge by the common fillet and torus, his ordinary workmen used to complete for him their one step a-piece per day, and david fraser his _three_ steps, finished equally well. it is easily conceivable how, in the higher walks of art, one man should excel a thousand--nay, how he should have neither competitor when living, nor successor when dead. the english gentleman who, after the death of canova, asked a surviving brother of the sculptor whether he purposed carrying on canova's _business_, found that he had achieved in the query an unintentional joke. but in the commoner avocations there appear no such differences between man and man; and it may seem strange how, in ordinary stone-cutting, one man could thus perform the work of three. my acquaintance with old john fraser showed me how very much the ability depended on a natural faculty. john's strength had never been above the average of that of scotchmen, and it was now considerably reduced; nor did his mallet deal more or heavier blows than that of the common workman. he had, however, an extraordinary power of conceiving of the finished piece of work, as lying within the rude stone from which it was his business to disinter it; and while ordinary stone-cutters had to repeat and re-repeat their lines and draughts, and had in this way virtually to give to their work several surfaces in detail ere they reached the true one, old john cut upon the true figure at once, and made one surface serve for all. in building, too, he exercised a similar power: he hammer-dressed his stones with fewer strokes than other workmen, and in fitting the interspaces between stones already laid, always picked from out of the heap at his feet the stone that exactly fitted the place; while other operatives busied themselves in picking up stones that were too small or too large; or, if they set themselves to reduce the too large ones, reduced them too little or too much, and had to fit and fit again. whether building or hewing, john never seemed in a hurry. he has been seen, when far advanced in life, working very leisurely, as became his years, on the one side of a wall, and two stout young fellows building against him on the other side--toiling, apparently, twice harder than he, but the old man always contriving to keep a little a-head of them both. david fraser i never saw; but as a hewer he was said considerably to excel even his brother john. on hearing that it had been remarked among a party of edinburgh masons, that, though regarded as the first of glasgow stone-cutters, he would find in the eastern capital at least his equals, he attired himself most uncouthly in a long-tailed coat of tartan, and, looking to the life the untamed, untaught, conceited little celt, he presented himself on monday morning, armed with a letter of introduction from a glasgow builder, before the foreman of an edinburgh squad of masons engaged upon one of the finer buildings at that time in the course of erection. the letter specified neither his qualifications nor his name: it had been written merely to secure for him the necessary employment, and the necessary employment it did secure. the better workmen of the party were engaged, on his arrival, in hewing columns, each of which was deemed sufficient work for a week; and david was asked, somewhat incredulously, by the foreman, "if he could hew?" "o yes, _he thought_ he could hew." "could he hew columns such as these!" "o yes, _he thought_ he could hew columns such as these." a mass of stone in which a possible column lay hid, was accordingly placed before david, not under cover of the shed, which was already occupied by workmen, but, agreeably to david's own request, directly in front of it, where he might be seen by all, and where he straightway commenced a most extraordinary course of antics. buttoning his long tartan coat fast around him, he would first look along the stone from the one end, anon from the other, and then examine it in front and rear; or, quitting it altogether for the time, he would take up his stand beside the other workmen, and, after looking at them with great attention, return and give it a few taps with the mallet, in a style evidently imitative of theirs, but monstrously a caricature. the shed all that day resounded with roars of laughter; and the only thoroughly grave man on the ground was he who occasioned the mirth of all the others. next morning david again buttoned his coat; but he got on much better this day than the former: he was less awkward and less idle, though not less observant than before: and he succeeded ere evening in tracing, in workman-like fashion, a few draughts along the future column. he was evidently greatly improving. on the morning of wednesday he threw off his coat; and it was seen that, though by no means in a hurry, he was seriously at work. there were no more jokes or laughter; and it was whispered in the evening that the strange highlander had made astonishing progress during the day. by the middle of thursday he had made up for his two days' trifling, and was abreast of the other workmen; before night he was far ahead of them; and ere the evening of friday, when they had still a full day's work on each of their columns, david's was completed in a style that defied criticism; and, his tartan coat again buttoned around him, he sat resting himself beside it. the foreman went out and greeted him. "well," he said, "you have beaten us all: you certainly _can_ hew!" "yes," said david; "i _thought_ i could hew columns. did the other men take much more than a week to learn?" "come, come, _david fraser_," replied the foreman; "we all guess who you are: you have had your joke out; and now, i suppose, we must give you your week's wages, and let you away." "yes," said david; "work waits for me in glasgow; but i just thought it might be well to know how you hewed on this east side of the country." john fraser was a shrewd, sarcastic old man, much liked, however, by his brother workmen; though his severe sayings--which, never accompanied by any ill-nature, were always tolerated in the barrack--did both himself and them occasional harm when repeated outside. to men who have to live for months together on oatmeal and salt, the difference between porridge with and porridge without milk is a very great difference indeed, both in point of salutariness and comfort; and i had succeeded in securing, on the ordinary terms, ere the arrival of john, what was termed a _set_ of skimmed milk from the wife of the gentleman at whose dwelling-house we were engaged in working. the skimmed milk was, however, by no means good: it was thin, blue, and sour; and we received it without complaint only because we knew that, according to the poet, it was "better just than want aye," and that there was no other dairy in that part of the country. but old john was less prudent; and, taking the dairy-maid to task in his quiet ironical style, he began by expressing wonder and regret that a grand lady like her mistress should be unable to distinguish the difference between milk and wine. the maid indignantly denied the fact _in toto_: her mistress, she said, did know the difference. "o no," replied john; "wine always gets better the longer it is kept, and milk always the worse; but your mistress, not knowing the difference, keeps her milk very long, in order to make it better, and makes it so very bad in consequence, that there are some days we can scarce eat it at all." the dairy-maid bridled up, and, communicating the remark to her mistress, we were told next morning that we might go for our milk to the next dairy, if we pleased, but that we would get none from her. and so, for four months thereafter, we had to do penance for the joke, on that not very luxurious viand "dry porridge." the pleasures of the table had occupied but small space amid the very scanty enjoyments of our barrack even before, and they were now so considerably reduced, that i could have almost wished at meal-times that--like the inhabitants of the moon, as described by baron munchausen--i could open up a port-hole in my side, and lay in at once provisions enough for a fortnight; but the infliction told considerably more on our constitutions than on our appetites; and we all became subject to small but very painful boils in the muscular parts of the body--a species of disease which seems to be scarce less certainly attendant on the exclusive use of oatmeal, than sea-scurvy on the exclusive use of salt meat. old john, however, though in a certain sense the author of our calamity, escaped all censure, while a double portion fell to the share of the gentleman's wife. i never met a man possessed of a more thoroughly mathematical head than this ancient mason. i know not that he ever saw a copy of euclid; but the principles of the work seemed to lie as self-evident truths in his mind. in the ability, too, of drawing shrewd inferences from natural phenomena, old john fraser excelled all the other untaught men i ever knew. until my acquaintance with him commenced, i had been accustomed to hear the removal of what was widely known in the north of scotland as "the travelled stone of petty," attributed to supernatural agency. an enormous boulder had been carried in the night-time by the fairies, it was said, from its resting place on the sea-beach, into the middle of a little bay--a journey of several hundred feet; but old john, though he had not been on the spot at the time, at once inferred that it had been carried, not by the fairies, but by a thick cake of ice, considerable enough, when firmly clasped round it, to float it away. he had seen, he told me, stones of considerable size floated off by ice on the shore opposite his cottage, in the upper reaches of the cromarty firth: ice was an agent that sometimes "walked off with great stones;" whereas he had no evidence whatever that the fairies had any powers that way; and so he accepted the agent which he knew, as the true one in the removal of the travelled stone, and not the hypothetical agents of which he knew nothing. such was the natural philosophy of old john; and in this special instance geologic science has since fully confirmed his decision. he was chiefly a favourite among us, however, from his even and cheerful temper, and his ability of telling humorous stories, that used to set the barrack in a roar, and in which he never spared himself, if the exhibition of a weakness or absurdity gave but point to the fun. his narrative of a visit to inverness, which he had made when an apprentice lad, to see a sheep-stealer hung, and his description of the terrors of a night-journey back, in which he fancied he saw men waving in the wind on almost every tree, till on reaching his solitary barrack he was utterly prostrated by the apparition of his own great-coat suspended from a pin, has oftener than once convulsed us with laughter. but john's humorous confessions, based as they always were on a strong good sense, that always saw the early folly in its most ludicrous aspect, never lowered him in our eyes. of his wonderful skill as a workman, much was incommunicable; but it was at least something to know the principles on which he directed the operations of what a phrenologist would perhaps term his extraordinary faculties of _form_ and _size_; and so i recognise old john as one of not the least useful nor able of my many teachers. some of his professional lessons were of a kind which the south and east country masons would be the better for knowing. in that rainy district of scotland of which we at this time occupied the central tract, rubble walls built in the ordinary style leak like the bad roofs of other parts of the country; and mansion-houses constructed within its precincts by qualified workmen from edinburgh and glasgow have been found to admit the water in such torrents as to be uninhabitable, until their more exposed walls had been slated over like their roofs. old john, however, always succeeded in building water-tight walls. departing from the ordinary rule of the builder elsewhere, and which on the east coast of scotland he himself always respected, he slightly elevated the under beds of his stones, instead of laying them, as usual, on the dead level; while along the edges of their upper beds he struck off a small rude champer; and by these simple contrivances, the rain, though driven with violence against his work, coursed in streams along its face, without entering into the interior and soaking through. for about six weeks we had magnificent weather--clear, sunny skies, and calm seas; and i greatly enjoyed my evening rambles amid the hills, or along the sea-shore. i was struck, in these walks, by the amazing abundance of the wild flowers which covered the natural meadows and lower hill-slopes--an abundance, as i have since remarked, equally characteristic of both the northern and western islands of scotland. the lower slopes of gairloch, of western sutherland, of orkney, and of the northern hebrides generally--though, for the purposes of the agriculturist, vegetation languishes, and wheat is never reared--are by many degrees richer in wild flowers than the fat loamy meadows of england. they resemble gaudy pieces of carpeting, as abundant in petals as in leaves. little of the rare is to be detected in these meadows, save, perhaps, that in those of western sutherland a few alpine plants may be found at a greatly lower level than elsewhere in britain; but the vast profusion of blossoms borne by species common to almost every other part of the kingdom, imparts to them an apparently novel character. we may detect, i am inclined to think, in this singular floral profusion, the operation of a law not less influential in the animal than the vegetable world, which, when hardship presses upon the life of the individual shrub or quadruped, so as to threaten its vitality, renders it fruitful on behalf of its species. i have seen the principle strikingly exemplified in the common tobacco plant, when reared in a northern country, in the open air. year after year it continued to degenerate, and to exhibit a smaller leaf and shorter stem, until the successors of what in the first year of trial had been rigorous plants, of some three to four feet in height, had in the sixth or eighth become mere weeds, of scarce as many inches. but while the as yet undegenerate plant had merely borne atop a few florets, which produced a small quantity of exceedingly minute seeds, the stunted weed, its descendant, was so thickly covered over in its season with its pale yellow bells, as to present the appearance of a nosegay; and the seeds produced were not only bulkier in the mass, but also individually of much greater size. the tobacco had grown productive in proportion as it had degenerated. in the common scurvy-grass, too--remarkable, with some other plants for taking its place among both the productions of our alpine heights and of our sea-shores--it will be found that, in proportion as its habitat proves ungenial, and its leaves and stems become dwarfish and thin, its little white cruciform flowers increase, till, in localities where it barely exists, as if on the edge of extinction, we find the entire plant forming a dense bundle of seed vessels, each charged to the full with seed. and in the gay meadows of gairloch and orkney, crowded with a vegetation that approaches its northern limit of production, we detect what seems to be the same principle chronically operative; and hence, it would seem, their extraordinary gaiety. their richly blossoming plants are the poor productive _irish_ of the vegetable world; for doubleday seems quite in the right in holding that the law extends to not only the inferior animals, but to our own species also. the lean, ill-fed sow and rabbit rear, it has been long known, a greatly more numerous progeny than the same animals when well cared for and fat; and every horse and cattle breeder knows that to over-feed his animals proves a sure mode of rendering them sterile. the sheep, if tolerably well pastured, brings forth only a single lamb at a birth; but if half-starved and lean, the chances are that it may bring forth two or three. and so it is also with the greatly higher human race. place them in circumstances of degradation and hardship so extreme as almost to threaten their existence as individuals, and they increase, as if in behalf of the species, with a rapidity without precedent in circumstances of greater comfort. the aristocratic families of a country are continually running out; and it requires frequent creations to keep up the house of lords; whereas our poorer people seem increasing in more than the arithmetical ratio. in skye, though fully two-thirds of the population emigrated early in the latter half of the last century, a single generation had scarce passed ere the gap was completely filled; and miserable ireland, as it existed ere the famine, would have been of itself sufficient, had the human family no other breeding-place, to people in a few ages the world. here too, in close neighbourhood with the flower-covered meadows, were there miserable cottages that were swarming with children--cottages in which, for nearly the half of every twelvemonth, the cereals were unknown as food, and whose over-toiled female inmates did all the domestic work, and more than half the work of the little fields outside. how exquisitely the sun sets in a clear, calm, summer evening over the blue hebrides! within less than a mile of our barrack, there rose a tall hill, whose bold summit commanded all the western isles, from sleat in skye, to the butt of the lewis. to the south lay the trap islands; to the north and west, the gneiss ones. they formed, however, seen from this hill, one great group, which, just as the sun had sunk, and sea and sky were so equally bathed in gold as to exhibit on the horizon no dividing line, seemed in their transparent purple--darker or lighter according to the distance--a group of lovely clouds, that, though moveless in the calm, the first light breeze might sweep away. even the flat promontories of sandstone, which, like outstretched arms, enclosed the outer reaches of the foreground--promontories edged with low red cliffs, and covered with brown heath--used to borrow at these times, from the soft yellow beam, a beauty not their own. amid the inequalities of the gneiss region within--a region more broken and precipitous, but of humbler altitude, than the great gneiss tract of the midland highlands--the chequered light and shade lay, as the sun declined, in strongly contrasted patches, that betrayed the abrupt inequalities of the ground, and bore, when all around was warm, tinted, and bright, a hue of cold neutral grey; while immediately over and beyond this rough sombre base there rose two noble pyramids of red sandstone, about two thousand feet in height, that used to flare to the setting sun in bright crimson, and whose nearly horizontal strata, deeply scored along the lines, like courses of ashlar in an ancient wall, added to the mural effect communicated by their bare fronts and steep rectilinear outlines. these tall pyramids form the terminal members, towards the south, of an extraordinary group of sandstone hills, of denudation unique in the british islands, to which i have already referred, and which extends from the northern boundary of assynt to near applecross. but though i formed at this time my first acquaintance with the group, it was not until many years after that i had an opportunity of determining the relations of their component beds to each other, and to the fundamental rocks of the country. at times my walks were directed along the sea-shore. naturalists well know how much the western coasts of scotland differ in their productions from its eastern ones; but it was a difference wholly new to me at this time; and though my limited knowledge enabled me to detect it in but comparatively few particulars, i found it no uninteresting task to trace it for myself in even these few. i was first attracted by one of the larger sea-weeds, _himanthalia lorea_--with its cup-shaped disc and long thong-like receptacles--which i found very abundant on the rocks here, but which i had never seen in the upper reaches of the moray firth, and which is by no means very common on any portion of the east coast. from the sea-weeds i passed to the shells, among which i detected not only a difference in the proportions in which the various species occurred, but also species that were new to me--such as a shell, not rare in gairloch, _nassa reticulata_, but rarely if ever seen in the moray or cromarty firths; and three other shells which i saw here for the first time, _trochus umbilicatus_, _trochus magus_, and _pecten niveus_.[ ] i found, too, that the common edible oyster, _ostrea edulis_, which on the east coast lies always in comparatively deep water, is sometimes found in the gairloch, as, for instance, in the little bay opposite flowerdale, in beds laid bare by the ebb of stream-tides. it is always interesting to come unexpectedly either upon a new species or a striking peculiarity in an old one; and i deemed it a curious and suggestive fact that there should be british shells still restricted to our western shores, and that have not yet made their way into the german ocean, along the coasts of either extremity of the island. are we to infer that they are shells of more recent origin than the widely-diffused ones? or are they merely feebler in their reproductive powers? and is the german ocean, as some of our geologists hold, a comparatively modern sea, into which only the hardier mollusca of rapid increase have yet made their way? further, i found that the true fishes differ considerably in the group on the opposite sides of the island. the haddock and whiting are greatly more common on the east coast: the hake and horse mackerel very much more abundant on the west. even where the species are the same on both sides, the varieties are different. the herring of the west coast is a short, thick, richly-flavoured fish, greatly superior to the large lean variety so abundant on the east; whereas the west-coast cod are large-headed, thin-bodied, pale-coloured fishes, inferior, even in their best season, to the darker-coloured, small-headed variety of the east. in no respect do the two coasts differ more, or at least to the north of the grampians, than in the transparency of the water. the bottom is rarely seen on the east coast at a depth of more than twenty feet, and not often at more than twelve; whereas on the west i have seen it very distinctly, during a tract of dry weather, at a depth of sixty or seventy feet. the handles of the spears used in gairloch in spearing flat fish and the common edible crab (_cancer pagurus_), are sometimes five-and-twenty feet in length--a length which might in vain be given to spear-handles upon the east coast, seeing that there, at such a depth of water, flat fish or crab was never yet seen from the surface. deceived by this transparency, i have plunged oftener than once over head and ears, when bathing among the rocks, in pools where i had confidently expected to find footing. from a rock that rose abrupt as a wall from the low-water level of stream tides to a little above the line of flood, i occasionally amused myself, when the evenings were calm, in practising the indian method of diving--that in which the diver carries a weight with him, to facilitate his sinking, and keep him steadily at the bottom. i used to select an oblong-shaped stone, of sixteen or eighteen pounds' weight, but thin enough to be easily held in one hand; and after grasping it fast, and quitting the rock edge, i would in a second or two find myself on the grey pebble-strewed ooze beneath, some twelve or fifteen feet from the surface, where i found i could steadily remain, picking up any small objects i chanced to select, until, breath failing, i quitted my hold of the stone. and then two or three seconds more were always sufficient to bring me to the surface again. there are many descriptions, in the works of the poets, of submarine scenery, but it is always scenery such as may be seen by an eye looking down into the water--not by an eye enveloped in it--and very different from that with which i now became acquainted. i found that in these hasty trips to the bottom i could distinguish masses and colours, but that i always failed to determine outlines. the minuter objects--pebbles, shells, and the smaller bunches of sea-weed--always assumed the circular form; the larger, such as detached rocks, and patches of sand, appeared as if described by irregular curves. the dingy gneiss rock rose behind and over me like a dark cloud, thickly dotted with minute circular spots of soiled white--the aspect assumed, as seen through the water, by the numerous specimens of univalve shells (_purpura lapillus_ and _patella vulgata_) with which it was speckled; beneath, the irregular floor seemed covered by a carpet that somewhat resembled in the pattern a piece of marbled paper, save that the circular or oval patches of which it was composed, and which had as their nuclei, stones, rocks, shell-fish, bunches of fuci, and fronds of laminaria, were greatly larger. there spread around a misty groundwork of green intensely deep along its horizon, but comparatively light overhead, in its middle sky, which had always its prodigy--wonderful circlets of light, that went widening outwards, and with whose delicate green there mingled occasional flashes of pale crimson. such was the striking though somewhat meagre scenery of a sea-bottom in gairloch, as seen by a human eye submerged in from two to three fathoms of water. there still continued to linger in this primitive district, at the time, several curious arts and implements, that had long become obsolete in most other parts of the highlands, and of which the remains, if found in england or the low country, would have been regarded by the antiquary as belonging to very remote periods. during the previous winter i had read a little work descriptive of an ancient ship, supposed to be danish, which had been dug out of the silt of an english river, and which, among other marks of antiquity, exhibited seams caulked with moss--a peculiarity which had set at fault, it was said, the modern ship-carpenter, in the chronology of his art, as he was unaware that there had ever been a time when moss was used for such a purpose. on visiting, however, a boat-yard at gairloch, i found the highland builder engaged in laying a layer of dried moss, steeped in tar, along one of his seams, and learned that such had been the practice of boat-carpenters in that locality from time immemorial. i have said that the little old highlander of the solitary shieling, whom we met on first commencing our quarrying labours beside his hut, was engaged in stripping with a pocket-knife long slender filaments from off a piece of moss-fir. he was employed in preparing these ligneous fibres for the manufacture of a primitive kind of cordage, in large use among the fishermen, and which possessed a strength and flexibility that could scarce have been expected from materials of such venerable age and rigidity as the roots and trunks of ancient trees, that had been locked up in the peat-mosses of the district for mayhap a thousand years. like the ordinary cordage of the rope-maker, it consisted of three strands, and was employed for haulsers, the cork-bauks of herring-nets, and the lacing of sails. most of the sails themselves were made, not of canvas, but of a woollen stuff, the thread of which, greatly harder and stouter than that of common plaid, had been spun on the distaff and spindle. as hemp and flax must have been as rare commodities of old in the western highlands, and the hebrides generally, as they both were thirty years ago in gairloch, whereas moss-fir must have been abundant, and sheep, however coarse their fleeces, common enough, it seems not improbable that the old highland fleets that fought in the "battle of the bloody bay," or that, in troublous times, when donald quarrelled with the king, ravaged the coasts of arran and ayrshire, may been equipped with similar sails and cordage. scott describes the fleet of the "lord of the isles," in the days of the bruce, as consisting of "proud galleys," "streamered with silk and tricked with gold." i suspect he would have approved himself a truer antiquary, though mayhap worse poet, had he described it as composed of very rude carvels, caulked with moss, furnished with sails of dun-coloured woollen stuff still redolent of the oil, and rigged out with brown cordage formed of the twisted fibres of moss-fir. the distaff and spindle was still, as i have said, in extensive use in the district. in a scattered village in the neighbourhood of our barrack, in which all the adult females were ceaselessly engaged in the manufacture of yarn, there was not a single spinning-wheel. nor, though all its cottages had their little pieces of tillage, did it boast its horse or plough. the cottars turned up the soil with the old highland implement, the _cass-chron_; and the necessary manure was carried to the fields in spring, and the produce brought home in autumn, on the backs of the women, in square wicker-work panniers, with slip-bottoms. how these poor highland women did toil! i have paused amid my labours under the hot sun, to watch them as they passed, bending under their load of peat or manure, and at the same time twirling the spindle as they crept along, and drawing out the never-ending thread from the distaff stuck in their girdles. their appearance in most cases betrayed their life of hardship. i scarce saw a gairloch woman of the humbler class turned of thirty, who was not thin, sallow, and prematurely old. the men, their husbands and brothers, were by no means worn out with hard work. i have seen them, time after time, sunning themselves on a mossy bank, when the females were thus engaged; and used, with my brother-workmen--who were themselves celts, but of the industrious, hardworking type--to feel sufficiently indignant at the lazy fellows. but the arrangement which gave them rest, and their wives and sisters hard labour, seemed to be as much the offspring of a remote age as the woollen sails and the moss-fir cordage. several other ancient practices and implements had at this time just disappeared from the district. a good meal-mill of the modern construction had superseded, not a generation before, several small mills with horizontal water-wheels, of that rude antique type which first supplanted the still more ancient handmill. these horizontal mills still exist, however--at least they did so only two years ago--in the gneiss region of assynt. the antiquary sometimes forgets that, tested by his special rules for determining periods, several ages may be found contemporary in contiguous districts of the same country. i am old enough to have seen the handmill at work in the north of scotland; and the traveller into the highlands of western sutherland might have witnessed the horizontal mill in action only two years ago. but to the remains of either, if dug out of the mosses or sand-hills of the southern counties, we would assign an antiquity of centuries. in the same way, the unglazed earthen pipkin, fashioned by the hand without the assistance of the potter's wheel, is held to belong to the "bronze and stone periods" of the antiquary; and yet my friend of the doocot cave, when minister of small isles, found the remains of one of these pipkins in the famous charnel cave of eigg, which belonged to an age not earlier than that of mary, and more probably pertained to that of her son james; and i have since learned, that in the southern portions of the long island, this same hand-moulded pottery of the bronze period has been fashioned for domestic use during the early part of the present century. a chapter devoted to these lingering, or only recently departed, arts of the primitive ages, would be a curious one; but i fear the time for writing it is now well-nigh past. my few facts on the subject may serve to show that, even as late as the year , some three days' journey into the highlands might be regarded as analogous in some respects to a journey into the past of some three or four centuries. but even since that comparatively recent period the highlands have greatly changed. after some six or eight weeks of warm sunny days and lovely evenings, there came on a dreary tract of rainy weather, with strong westerly gales; and for three months together, while there was scarce a day that had not its shower, some days had half-a-dozen. gairloch occupies, as i have said, exactly the focus of that great curve of annual rain which, impinging on our western shores from the atlantic, extends from the north of assynt to the south of mull, and exhibits on the rain-gauge an average of thirty-five yearly inches--an average very considerably above the medium quantity that falls in any other part of great britain, save a small tract at the land's end, included in a southern curve of equal fall. the rain-fall of this year, however, must have stood very considerably above even this high average; and the corn crops of the poor highlanders soon began to testify to the fact. there had been a larger than ordinary promise during the fine weather; but in the danker hollows the lodged oats and barley now lay rotting on the ground, or, on the more exposed heights, stood up, shorn of the ears, as mere naked spikes of straw. the potatoes, too, had become soft and watery, and must have formed but indifferent food to the poor highlanders, condemned, even in better seasons, to feed upon them during the greater part of the year, and now thrown upon them almost exclusively by the failure of the corn crop. the cottars of the neighbouring village were on other accounts in more than usually depressed circumstances at the time. each family paid to the laird for its patch of corn-land, and the pasturage of a wide upland moor, on which each kept three cows a-piece, a small yearly rent of three pounds. the males were all fishermen as well as crofters; and, small as the rent was, they derived their only means of paying it from the sea--chiefly, indeed, from the herring fishery--which, everywhere an uncertain and precarious source of supply, is more so here than in most other places on the north-western coasts of scotland. and as for three years together the herring fishing had failed in the loch, they had been unable, term after term, to meet with the laird, and were now three years in arrears. fortunately for them, he was a humane, sensible man, comfortable enough in his circumstances to have, what highland proprietors often have not, the complete command of his own affairs; but they all felt that their cattle were their own only by sufferance, and so long as he forbore urging his claims against them; and they entertained but little hope of ultimate extrication. i saw among these poor men much of that indolence of which the country has heard not a little; and could not doubt, from the peculiar aspects in which it presented itself, that it was, as i have said, a long-derived hereditary indolence, in which their fathers and grandfathers had indulged for centuries. but there was certainly little in their circumstances to lead to the formation of new habits of industry. even a previously industrious people, were they to be located within the great north-western curve of thirty-five inch rain, to raise corn and potatoes for the autumnal storms to blast, and to fish in the laird's behalf herrings that year after year refused to come to be caught, would, i suspect, in a short time get nearly as indolent as themselves. and certainly, judging from the contrast which my brother-workmen presented to these highlanders of the west coast, the indolence which we saw, and for which my comrades had no tolerance whatever, could scarce be described as inherently celtic. i myself was the only genuine lowlander of our party. john fraser, who, though turned of sixty, would have laid or hewn stone for stone with the most diligent saxon mason in britain or elsewhere, was a true celt of the scandinavian-gaelic variety; and all our other masons--macdonalds, m'leods, and mackays, hard-working men, who were content to toil from season to season, and all day long--were true celts also. but they had been bred on the eastern border of the highlands, in a sandstone district, where they had the opportunity of acquiring a trade, and of securing in the working season regular well-remunerated employment; and so they had developed into industrious, skilled mechanics, of at least the ordinary efficiency. there are other things much more deeply in fault as producing causes of the indolence of the west-coast highlander than his celtic blood. on finishing the dwelling-house upon which we had been engaged, nearly one-half the workmen quitted the squad for the low country, and the remainder removed to the neighbourhood of the inn at which we had spent our first night, or rather morning, in the place, to build a kitchen and store-room for the inn-keeper. among the others, we lost the society of click-clack, who had been a continual source of amusement and annoyance to us in the barrack all the season long. we soon found that he was regarded by the highlanders in our neighbourhood with feelings of the intensest horror and dread: they had learned somehow that he used to be seen in the low country flitting suspiciously at nights about churchyards, and was suspected of being a resurrectionist; and not one of the ghouls or vampires of eastern story could have been more feared or hated in the regions which they were believed to infest, than a resurrectionist in the western highlands. click-clack had certainly a trick of wandering about at nights; and not unfrequently did he bring, on his return from some nocturnal ramble, dead bodies with him into the barrack; but they were invariably the dead bodies of cod, gurnard, and hake. i know not where his fishing-bank lay, or what bait he employed; but i observed that almost all the fish which he caught were ready dried and salted. old john fraser was not without suspicion that there were occasional interferences on the part of the carter with the integrity of our meal-barrel; and i have seen the old man smoothing the surface of the meal just before quitting the barrack for his work, and inscribing upon it with his knife-point the important moral injunction, "thou shalt not steal," in such a way as to render it impossible to break the commandment within the precincts of the barrel, without, at the same time, effacing some of its characters. and these once effaced, click-clack, as he was no writer himself, and had no assistant or confidant, could not have re-inscribed. ere quitting us for the low country, i bargained with him that he should carry my blanket in his cart to conon-side, and gave him a shilling and a dram in advance, as pay for the service. he carried it, however, no further than the next inn, where, pledging it for a second shilling and second dram, he left me to relieve it as i passed. poor click-clack, though one of the cleverest of his class, was decidedly half-witted; and i may remark, as at least curious, that though i have known idiocy in its unmixed state united to great honesty, and capable of disinterested attachment, i never yet knew one of the half-witted caste who was not selfish and a rogue. we were unlucky in our barracks this season. ere completing our first piece of work, we had to quit the hay-barn, our earliest dwelling, to make way for the proprietor's hay, and to shelter in a cow-house, where, as the place had no chimney, we were nearly suffocated by smoke; and we now found the innkeeper, our new employer, speculating, like the magistrates in joe miller, on the practicability of lodging us in a building, the materials of which were to be used in erecting the one which we were engaged to build. we did our best to solve the problem, by hanging up at the end of the doomed hovel--which had been a salt-store in its day, and was in damp weather ever sweating salt-water--a hanging partition of mats, that somewhat resembled the curtain of a barn-theatre; and, making our beds within, we began pulling down piecemeal, as the materials were required, that part of the erection which lay outside. we had very nearly unhoused ourselves ere our work was finished; and the chill blasts of october, especially when they blew in at the open end of our dwelling, rendered it as uncomfortable as a shallow cave in an exposed rock-front. my boyish experiences, however, among the rocks of cromarty, constituted no bad preparation for such a life, and i roughed it out at least as well as any of my comrades. the day had so contracted, that night always fell upon our unfinished labours, and i had no evening walks; but there was a delightful gneiss island, of about thirty acres in extent, and nearly two miles away, to which i used to be occasionally despatched to quarry lintels and corner stones, and where work had all the charms of play; and the quiet sabbaths were all my own. so long as the laird and his family were at the mansion-house of flowerdale--at least four months of every year--there was an english service in the parish church; but i had come to the place this season before the laird, and now remained in it after he had gone away, and there was no english service for me. and so i usually spent my sabbaths all alone in the noble flowerdale woods, now bright under their dark hillsides, in the autumnal tints, and remarkable for the great height and bulk of their ash trees, and of a few detached firs, that spoke, in their venerable massiveness, of former centuries. the clear, calm mornings, when the gossamer went sailing in long grey films along the retired glades of the wood, and the straggling sunlight fell on the crimson and orange mushroom, as it sprang up amid the dank grass, and under thickly-leaved boughs of scarlet and gold, i deemed peculiarly delightful. for one who had neither home nor church, the autumnal woods formed by much a preferable sabbath haunt to a shallow cave, dropping brine, unprovided with chair or table, and whose only furniture consisted of two rude bedsteads of undressed slabs, that bore atop two blankets a-piece, and a heap of straw. sabbath-walking in parties, and especially in the neighbourhood of our large towns, is always a frivolous, and often a very bad thing; but lonely sabbath-walks in a rural district--walks such as the poet graham describes--are not necessarily bad; and the sabbatarians who urge that in all cases, men, when not in church on the sabbath, ought to be in their dwellings, must know very little indeed of the "huts where poor men lie." in the mason's barrack, or the farm-servant's bothy, it is often impossible to enjoy the quiet of the sabbath: the circumstances necessary to its enjoyment must be sought in the open air, amid the recesses of some thick wood, or along the banks of some unfrequented river, or on the brown wastes of some solitary moor. we had completed all our work ere hallowday, and, after a journey of nearly three days, i found myself once more at home, with the leisure of the long happy winter before me. i still look lack on the experiences of this year with a feeling of interest. i had seen in my boyhood, in the interior of sutherland, the highlanders living in that condition of comparative comfort which they enjoyed from shortly after the suppression of the rebellion of , and the abolition of the hereditary jurisdictions, till the beginning of the present century, and in some localities for ten or twelve years later. and here again i saw them in a condition--the effect mainly of the introduction of the extensive sheep-farm system into the interior of the country--which has since become general over almost the entire highlands, and of which the result may be seen in the annual famines. the population, formerly spread pretty equally over the country, now exists as a miserable selvedge, stretched along its shores, dependent in most cases on precarious fisheries, that prove remunerative for a year or two, and disastrous for mayhap half-a-dozen; and able barely to subsist when most successful, a failure in the potato crop, or in the expected return of the herring shoals, at once reduces them to starvation. the grand difference between the circumstances of the people of the highlands in the better time and the worse may be summed up in the one important vocable--_capital_. the highlander was never wealthy: the inhabitants of a wild mountainous district, formed of the primary rocks, never are. but he possessed, on the average, his six, or eight, or ten head of cattle, and his small flock of sheep; and when, as sometimes happened in the high-lying districts, the corn-crop turned out a failure, the sale of a few cattle or sheep more than served to clear scores with the landlord, and enabled him to purchase his winter and spring supply of meal in the lowlands. he was thus a capitalist, and possessed the capitalist's peculiar advantage of not "living from hand to mouth," but on an accumulated fund, which always stood between him and absolute want, though not between him and positive hardship, and which enabled him to rest, during a year of scarcity, on his own resources, instead of throwing himself on the charity of his lowland neighbours. nay, in what were emphatically termed "the dear years" of the beginning of the present and latter half of the past century, the humble people of the lowlands, especially our lowland mechanics and labourers, suffered more than the crofters and _small_ farmers of the highlands, and this mainly from the circumstance, that as the failure of the crops which induced the scarcity was a corn failure, not a failure of grass and pasture, the humbler highlanders had sheep and cattle, which continued to supply them with food and raiment; while the humbler lowlanders, depending on corn almost exclusively, and accustomed to deal with the draper for their articles of clothing, were reduced by the high price of provisions to great straits. there took place, however, about the beginning of the century, a mighty change, coincident with, and, to a certain extent, an effect of, the wars of the first french revolution. the price of provisions rose in england and the lowlands, and with the price of provisions, the rent of land. the highland proprietor naturally enough set himself to determine how his rental also was to be increased; and, as a consequence of the conclusion at which he arrived, the sheep-farm and clearance system began. many thousand highlanders, ejected from their snug holdings, employed their little capital in emigrating to canada and the states; and there, in most cases, the little capital increased, and a rude plenty continues to be enjoyed by their descendants. many thousands more, however, fell down upon the coasts of the country, and, on moss-covered moors or bare promontories, ill suited to repay the labours of the agriculturist, commenced a sort of amphibious life as crofters and fishermen. and, located on an ungenial soil, and prosecuting with but indifferent skill a precarious trade, their little capital dribbled out of their hands, and they became the poorest of men. meanwhile, in some parts of the highlands and islands a busy commerce sprang up, which employed--much to the profit of the landlords--many thousands of the inhabitants. the kelp manufacture rendered inhospitable islets and tracts of bleak rocky shore, rich in sea-weed, of as much value to the proprietors as the best land in scotland; and, under the impetus given by full employment, and, if not ample, at least remunerative pay, population increased. suddenly, however, free trade, in its first approaches, destroyed the trade in kelp; and then the discovery of a cheap mode of manufacturing soda out of common salt secured its ruin beyond the power of legislation to retrieve. both the people and landlords experienced in the kelp districts the evils which a ruined commerce always leaves behind it. old highland families disappeared from amid the aristocracy and landowners of scotland; and the population of extensive islands and sea-boards of the country, from being no more than adequate, suddenly became oppressively redundant. it required, however, another drop to make the full cup run over. the potatoes had become, as i have shown, the staple food of the highlander; and when, in , the potato-blight came on, the people, most of them previously stripped of their little capitals, and divested of their employment, were deprived of their food, and ruined at a blow. the same stroke which did little more than slightly impinge on the comforts of the people of the lowlands, utterly prostrated the highlanders; and ever since, the sufferings of famine have become chronic along the bleak shores and rugged islands of at least the north-western portion of our country. nor is it perhaps the worst part of the evil that takes the form of clamorous want: so heavily have the famines borne on a class which were not absolutely the poor when they came on, that they are absolutely the poor now;--they have dissipated the last remains of capital possessed by the _people_ of the highlands. footnotes: [ ] appended to their joint paper on the "deposits contained between the scottish primary rocks and oolitic series," and interesting, as the first published geological map of scotland to the north of the firths of forth and clyde. [ ] there are only two of these exclusively west-coast shells,--_trochus umbilicatus_ and _pecten niveus_. as neither of them has yet been detected in any tertiary formation, they are in all probability shells of comparatively recent origin, that came into existence in some western centre of creation; whereas specimens of _trochus magus_ and _nassa reticulata_, which occasionally occur on the eastern coasts of the kingdom, i have also found in a pleistocene deposit. thus the more widely-spread shells seem to be also the shells of more ancient standing. chapter xiv. "edina! scotia's darling seat! all hail thy palaces and towers!"--burns. there had occurred a sad accident among the cromarty rocks this season, when i was labouring in gairloch, which, from the circumstance that it had nearly taken place in my own person about five years before, a good deal impressed me on my return. a few hundred yards from the very bad road which i had assisted old johnstone of the forty-second in constructing, there is a tall inaccessible precipice of ferruginous gneiss, that from time immemorial down to this period had furnished a secure nestling-place to a pair of ravens--the only birds of their species that frequented the rocks of the hill. year after year, regularly as the breeding season came round, the ravens used to make their appearance, and enter on possession of their hereditary home: they had done so for a hundred years, to a certainty--some said, for a much longer time; and as there existed a tradition in the place that the nest had once been robbed of its young birds by a bold climber, i paid it a visit one morning, in order to determine whether i could not rob it too. there was no getting up to it from below: the precipice, more inaccessible for about a hundred feet from its base than a castle wall, overhung the shore; but it seemed not impracticable from above; and, coming gradually down upon it, availing myself, as i crept along, of every little protuberance and hollow, i at length stood within six or eight feet of the young birds. from that point, however, a smooth shelf, without projection or cavity, descended at an angle of about forty to the nest, and terminated abruptly, without ledge or margin, in the overhanging precipice. have i not, i asked, crept along a roof of even a steeper slope than that of the shelf? why not, in like manner, creep along it to the nest, where there is firm footing? i had actually stretched out my naked foot to take the first step, when i observed, as the sun suddenly broke out from behind a cloud, that the light glistened on the smooth surface. it was incrusted over by a thin layer of chlorite, slippery as the mixture of soap and grease that the ship-carpenter spreads over his slips on the morning of a launch. i at once saw there was an element of danger in the way, on which i had at first failed to calculate; and so, relinquishing the attempt as hopeless, i returned by the path i had come, and thought no more of robbing the raven's nest. it was, however, again attempted this season, but with tragic results, by a young lad from sutherland, named mackay, who had previously approved his skill as a cragsman in his native county, and several times secured the reward given by an agricultural society for the destruction of young birds of prey. as the incident was related to me, he had approached the nest by the path which i had selected; he had paused where i had paused, and even for a longer time; and then, venturing forward, he no sooner committed himself to the treacherous chlorite, than, losing footing as if on a steep sheet of ice, he shot right over the precipice. falling sheer for the first fifty feet or so without touching the rock, he was then turned full round by a protuberance against which he had glanced, and, descending for the lower half of the way head foremost, and dashing with tremendous force among the smooth sea-stones below, his brains were scattered over an area of from ten to twelve square yards in extent. his only companion--an ignorant irish lad--had to gather up the fragments of his head in a napkin. i now felt that, save for the gleam of the sun on the glistening chlorite--seen not a moment too soon--i should probably have been substituted as the victim for poor mackay, and that he, warned by my fate, would in all likelihood have escaped. and though i knew it might be asked, why the interposition of a providence to save _you_, when he was left to perish? i _did_ feel that i did not owe my escape merely to my acquaintance with chlorite and its properties. for the full development of the moral instincts of our nature, one may lead a life by much too quiet and too secure: a sprinkling in one's lot of sudden perils and hair-breadth escapes is, i am convinced, more wholesome, if positive superstition be avoided, than a total absence of danger. for my own part, though i have, i trust, ever believed in the doctrine of a particular providence, it has been always some narrow escape that has given me my best evidences of the vitality and strength of the belief within. it has ever been the touch of danger that has rendered it emotional. a few years after this time, when stooping forward to examine an opening fissure in a rock front, at which i was engaged in quarrying, a stone, detached from above by a sudden gust of wind, brushed so closely past my head as to beat down the projecting front of my bonnet, and then dented into a deep hollow the sward at my feet. there was nothing that was not perfectly natural in the occurrence; but the gush of acknowledgment that burst spontaneously from my heart would have set at nought the scepticism which should have held that there was no providence in it. on another occasion, i paused for some time, when examining a cave of the old-coast line, directly under its low-browed roof of old red conglomerate, as little aware of the presence of danger as if i had been standing under the dome of st. paul's; but when i next passed the way, the roof had fallen, and a mass, huge enough to have given me at once death and burial, cumbered the spot which i had occupied. on yet another occasion, i clambered a few yards down a precipice, to examine some crab-apple trees, which, springing from a turret-like projection of the rock, far from gardens and nurseries, had every mark of being indigenous; and then, climbing up among the branches, i shook them in a manner that must have exerted no small leverage power on the outjet beneath, to possess myself of some of the fruit, as the native apples of scotland. on my descent, i marked, without much thinking of the matter, an apparently recent crack running between the outjet and the body of the precipice. i found, however, cause enough to think of it on my return, scarce a month after; for then both outjet and trees lay broken and fractured on the beach more than a hundred feet below. with such momentum had even the slimmer twigs been dashed against the sea-pebbles, that they stuck out from under more than a hundred tons of fallen rock, divested of the bark on their under sides, as if peeled by the hand. and what i felt on all these occasions was, i believe, not more in accordance with the nature of man as an instinct of the moral faculty, than in agreement with that provision of the divine government under which a sparrow falleth not without permission. there perhaps never was a time in which the doctrine of a particular providence was more questioned and doubted than in the present; and yet the scepticism which obtains regarding it seems to be very much a scepticism of effort, conjured up by toiling intellects, in a quiet age, and among the easy classes; while the belief which, partially and for the time, it overshadows, lies safely entrenched all the while amid the fastnesses of the unalterable nature of man. when danger comes to touch it, it will spring up in its old proportions; nay, so indigenous is it to the human heart, that if it will not take its _cultivated_ form as a belief in providence, it will to a certainty take to it its _wild_ form as a belief in fate or destiny. of a doctrine so fundamentally important that there can be no religion without it, god himself seems to have taken care when he moulded the human heart. the raven no longer builds among the rocks of the hill of cromarty; and i saw many years ago its last pair of eagles. this last noble bird was a not unfrequent visitor of the sutors early in the present century. i still remember scaring it from its perch on the southern side of the hill, as day was drawing to a close, when the tall precipices amid which it had lodged lay deep in the shade; and vividly recollect how picturesquely it used to catch the red gleam of evening on its plumage of warm brown, as, sailing outwards over the calm sea many hundred feet below, it emerged from under the shadow of the cliffs into the sunshine. uncle james once shot a very large eagle beneath one of the loftiest precipices of the southern sutor; and, swimming out through the surf to recover its body--for it had dropped dead into the sea--he kept its skin for many years as a trophy.[ ] but eagles are now no longer to lie seen or shot on the sutors or their neighbourhood. the badger, too--one of perhaps the oldest inhabitants of the country, for it seems to have been contemporary with the extinct elephants and hyænas of the pleistocene periods--has become greatly less common on their steep sides than in the days of my boyhood; and both the fox and otter are less frequently seen. it is not uninteresting to mark with the eye of the geologist, how palpably in the course of a single lifetime--still nearly twenty years short of the term fixed by the psalmist--these wild animals have been posting on in scotland to that extinction which overtook, within its precincts, during the human period, the bear, the beaver, and the wolf, and of which the past history of the globe, as inscribed on its rocks, furnishes so strong a record. winter passed in the usual pursuits; and i commenced the working season of a new year by assisting my old master to inclose with a stone wall a little bit of ground, which he had bought on speculation, but had failed in getting feued out for buildings. my services, however, were gratuitous--given merely to eke out the rather indifferent bargain that the old man had been able to drive in his own behalf for my labours as an apprentice; and when our job was finished, it became necessary that i should look out for employment of a more profitable character. there was not much doing in the north; but work promised to be abundant in the great towns of the south: the disastrous building mania of - had just begun, and, after some little hesitation, i resolved on trying whether i could not make my way as a mechanic among the stone-cutters of edinburgh perhaps the most skilful in their profession in the world. i was, besides, desirous to get rid of a little property in leith, which had cost the family great annoyance, and not a little money, but from which, so long as the nominal proprietor was a minor, we could not shake ourselves loose. it was a house on the coal-hill, or rather the self-contained ground-floor of a house, which had fallen to my father through the death of a relative, so immediately before his own death that he had not entered upon possession. it was burdened with legacies to the amount of nearly two hundred pounds; but then the yearly rent amounted to twenty-four pounds; and my mother, acting on the advice of friends, and deeming the investment a good one, had no sooner recovered the insurance-money of my father's vessel from the underwriter, than she handed the greater part of it to the legatees, and took possession of the property in my behalf. alas! never was there a more unfortunate inheritance or worse investment. it had been let as a public-house and tap-room, and had been the scene of a somewhat rough, and, i daresay, not very respectable, but yet profitable trade; but no sooner had it become mine than, in consequence of some alterations in the harbour, the greater part of the shipping that used to lie at the coal-hill removed to a lower reach; the tap-room business suddenly fell off; and the rent sank, during the course of one twelvemonth, from twenty-four to twelve pounds. and then in its sear and wintry state, the unhappy house came to be inhabited by a series of miserable tenants, who, though they sanguinely engaged to pay the twelve pounds, never paid them. i still remember the brief, curt letters from our agent, the late mr. veitch, town-clerk of leith, that never failed to fill my mother with terror and dismay, and very much resembled, in at least the narrative parts, jottings by the poet crabbe, for some projected poem on the profligate poor. two of our tenants made moonlight flittings just on the eve of the term; and though the little furniture which they left behind them was duly rouped at the cross, such was the inevitable expense of the transaction, that none of the proceeds of the sale reached cromarty. the house was next inhabited by a stout female, who kept a certain description of lady-lodgers; and for the first half-year she paid the rent most conscientiously; but the authorities interfering, there was another house found for her and her ladies in the neighbourhood of the calton, and the rent of the second half-year remained unpaid. and as the house lost, in consequence of her occupation, the modicum of character which it had previously retained, it lay for five years wholly untenanted, save by a mischievous spirit--the ghost, it was said, of a murdered gentleman, whose throat had been cut in an inner apartment by the ladies, and his body flung by night into the deep mud of the harbour. the ghost was, however, at length detected by the police, couching in the form of one of the ladies themselves, on a lair of straw in the corner of one of the rooms, and exorcised into bridewell; and then the house came to be inhabited by a tenant who had both the will and the ability to pay. one year's rent, however, had to be expended in repairs; and ere the next year passed, the heritors of the parish were rated for the erection of the magnificent parish church of north leith, then in course of building, with its tall and graceful spire and classic portico; and as we had no one to state our case, our house was rated, not according to its reduced, but according to its original value. and so the entire rental of the second year, with several pounds additional which i had to subtract from my hard-earned savings as a mason, were appropriated in behalf of the ecclesiastical establishment of the country, by the builders of the church and spire. i had attained my majority when lodging in the fragment of a salt storehouse in gairloch; and, competent in the eye of the law to dispose of the house on the coal-hill, i now hoped to find, if not a purchaser, at least some one foolish enough to take it off my hands for nothing. i have since heard and read a good deal about the atrocious landlords of the poorer and less reputable sort of houses in our large towns, and have seen it asserted that, being a bad and selfish kind of people, they ought to be rigorously dealt with. and so, i daresay, they ought; but at the same time i cannot forget, that i myself was one of these atrocious landlords from my fifth till nearly my twenty-second year, and that i could not possibly help it, and was very sorry for it. on the fourth day after losing sight of the hill of cromarty, the leith smack in which i sailed was slowly threading her way, in a morning of light airs and huge broken fog-wreaths, through the lower tracts of the firth of forth. the islands and distant land looked dim and grey through the haze, like objects in an unfinished drawing; and at times some vast low-browed cloud from the sea applied the sponge as it rolled past, and blotted out half a county at a time; but the sun occasionally broke forth in partial glimpses of great beauty, and brought out into bold relief little bits of the landscape--now a town, and now an islet, and anon the blue summit of a hill. a sunlit wreath rose from around the abrupt and rugged bass as we passed; and my heart leaped within me as i saw, for the first time, that stern patmos of the devout and brave of another age looming dark and high through the diluted mist, and enveloped for a moment, as the cloud parted, in an amber-tinted glory. there had been a little presbyterian oasis of old in the neighbourhood of cromarty, which, in the midst of the highland and _moderate_ indifferency that characterized the greater part of the north of scotland during the seventeenth century, had furnished the bass with not a few of its most devoted victims. mackilligen of alness, hogg of kiltearn, and the rosses of tain and kincardine, had been incarcerated in its dungeons; and, when labouring in the cromarty quarries in early spring, i used to know that it was time to gather up my tools for the evening, when i saw the sun resting over the high-lying farm which formed the patrimony of another of its better-known victims--young fraser of brea. and so i looked with a double interest on the bold sea-girt rock, and the sun-gilt cloud that rose over its scared forehead, like that still brighter halo which glorifies it in the memories of the scottish people. many a long-cherished association drew my thoughts to edinburgh. i was acquainted with ramsay, and fergusson, and the "humphrey clinker" of smollett, and had read a description of the place in the "marmion" and the earlier novels of scott; and i was not yet too old to feel as if i were approaching a great magical city--like some of those in the "arabian nights"--that was even more intensely poetical than nature itself. i did somewhat chide the tantalizing mist, that, like a capricious showman, now raised one corner of its curtain, and anon another, and showed me the place at once very indistinctly, and only by bits at a time; and yet i know not that i could in reality have seen it to greater advantage, or after a mode more in harmony with my previous conceptions. the water in the harbour was too low, during the first hour or two after our arrival, to float our vessel, and we remained tacking in the roadstead, watching for the signal from the pier-head which was to intimate to us when the tide had risen high enough for our admission; and so i had sufficient time given me to con over the features of the scene, as presented in detail. at one time a flat reach of the new town came full into view, along which, in the general dimness, the multitudinous chimneys stood up like stacks of corn in a field newly reaped; at another, the castle loomed out dark in the cloud; then, as if suspended over the earth, the rugged summit of arthur's seat came strongly out, while its base still remained invisible in the wreath; and anon i caught a glimpse of the distant pentlands, enveloped by a clear blue sky, and lighted up by the sun. leith, with its thicket of masts, and its tall round tower, lay deep in shade in the foreground--a cold, dingy, ragged town, but so strongly relieved against the pale smoky grey of the background, that it seemed another little city of zoar, entire in front of the burning. and such was the strangely picturesque countenance with which i was favoured by the scottish capital, when forming my earliest acquaintance with it, twenty-nine years ago. it was evening ere i reached it. the fog of the early part of the day had rolled off, and every object stood out in clear light and shade under a bright sunshiny sky. the workmen of the place--their labours just closed for the day--were passing in groups along the streets to their respective homes; but i was too much engaged in looking at the buildings and shops to look very discriminately at them; and it was not without some surprise that i found myself suddenly laid hold of by one of their number, a slim lad, in pale moleskin a good deal bespattered with paint. my friend william ross stood before me; and his welcome on the occasion was a very hearty one. i had previously taken a hasty survey of my unlucky house in leith, accompanied by a sharp, keen-looking, one-handed man of middle age, who kept the key, and acted, under the town-clerk, as general manager; and who, as i afterwards ascertained, was the immortal peter m'craw. but i had seen nothing suited to put me greatly in conceit with my patrimony. it formed the lowermost floor of an old black building, four stories in height, flanked by a damp narrow court along one of its sides, and that turned to the street its sharp-peaked, many-windowed gable. the lower windows were covered up by dilapidated, weather-bleached shutters; in the upper, the comparatively fresh appearance of the rags that stuffed up holes where panes ought to have been, and a few very pale-coloured petticoats and very dark-coloured shirts fluttering in the wind, gave evident signs of habitation. it cost my conductor's one hand an arduous wrench to lay open the lock of the outer door, in front of which he had first to dislodge a very dingy female, attired in an earth-coloured gown, that seemed as if starched with ashes; and as the rusty hinges creaked, and the door fell against the wall, we became sensible of a damp, unwholesome smell, like the breath of a charnel-house, which issued from the interior. the place had been shut up for nearly two years; and so foul had the stagnant atmosphere become, that the candle which we brought with us to explore burned dim and yellow like a miner's lamp. the floors, broken up in fifty different places, were littered with rotten straw; and in one of the corners there lay a damp heap, gathered up like the lair of some wild beast, on which some one seemed to have slept, mayhap months before. the partitions were crazed and tottering; the walls blackened with smoke; broad patches of plaster had fallen from the ceilings, or still dangled from them, suspended by single hairs; and the bars of the grates, crusted with rust, had become red as foxtails. mr. m'craw nodded his head over the gathered heap of straw. "ah," he said--"got in again, i see! the shutters must be looked to." "i daresay," i remarked, looking disconsolately around me, "you don't find it very easy to get tenants for houses of this kind." "_very_ easy!" said mr. m'craw, with somewhat of a highland twang, and, as i thought, with also a good deal of highland _hauteur_--as was of course quite natural in so shrewd and extensive a house-agent, when dealing with the owner of a domicile that would not let, and who made foolish remarks--"no, nor easy at all, or it would not be locked up in this way: but if we took off the shutters you would soon get tenants enough." "oh, i suppose so; and i daresay it is as difficult to sell as to let such houses." "ay, and more," said mr. m'craw: "it's all sellers, and no buyers, when we get this low." "but do you not think," i perseveringly asked, "that some kind, charitable person might be found in the neighbourhood disposed to take it off my hands as a free gift! it's terrible to be married for life to a baggage of a house like this, and made liable, like other husbands, for all its debts. is there no way of getting a divorce?" "don't know," he emphatically replied, with somewhat of a nasal snort; and so we parted; and i saw or heard no more of peter m'craw until many years after, when i found him celebrated in the well-known song by poor gilfillan.[ ] and in the society of my friend i soon forgot my miserable house, and all the liabilities which it entailed. i was as entirely unacquainted with great towns at this time as the shepherd in virgil; and, excited by what i saw, i sadly tasked my friend's peripatetic abilities, and, i fear, his patience also, in taking an admiring survey of all the more characteristic streets, and then in setting out for the top of arthur's seat--from which, this evening, i watched the sun set behind the distant lomonds--that i might acquaint myself with the features of the surrounding country, and the effect of the city as a whole. and amid much confused and imperfect recollection of picturesque groups of ancient buildings, and magnificent assemblages of elegant modern ones, i carried away with me two vividly distinct ideas--first results, as a painter might perhaps say, of a "fresh eye," which no after survey has served to freshen or intensify. i felt that i had seen, not one, but two cities--a city of the past and a city of the present--set down side by side, as if for purposes of comparison, with a picturesque valley drawn like a deep score between them, to mark off the line of division. and such in reality seems to be the grand peculiarity of the scottish capital--its distinguishing trait among the cities of the empire; though, of course, during the twenty-nine years that have elapsed since i first saw it, the more ancient of its two cities--greatly modernized in many parts--has become less uniformly and consistently antique in its aspect. regarded simply as matters of taste, i have found little to admire in the improvements that have so materially changed its aspect. of its older portions i used never to tire: i found i could walk among them as purely for the pleasure which accrued, as among the wild and picturesque of nature itself; whereas one visit to the elegant streets and ample squares of the new city always proved sufficient to satisfy; and i certainly never felt the desire to return to any of them to saunter in quest of pleasure along the smooth, well-kept pavements. i of course except princes street. there the two cities stand ranged side by side, as if for comparison; and the eye falls on the features of a natural scenery that would of itself be singularly pleasing even were both the cities away. next day i waited on the town-clerk, mr. veitch, to see whether he could not suggest to me some way in which i might shake myself loose from my unfortunate property on the coal-hill. he received me civilly--told me that the property was not quite so desperate an investment as i seemed to think it, as at least the site, in which i had an interest with the other proprietors, was worth something, and as the little courtyard was exclusively my own; and that he thought he could get the whole disposed of for me, if i was prepared to accept of a small price. and i was of course, as i told him, prepared to accept of a very small one. further, on learning that i was a stone-cutter, and unemployed, he kindly introduced me to one of his friends, a master-builder, by whom i was engaged to work at a manor-house a few miles to the south of edinburgh. and procuring "lodgings" in a small cottage of but a single apartment, near the village of niddry mill, i commenced my labours as a hewer under the shade of the niddry woods. there was a party of sixteen masons employed at niddry, besides apprentices and labourers. they were accomplished stone-cutters--skilful, especially in the cutting of mouldings, far above the average of the masons of the north country; and it was with some little solicitude that i set myself to labour beside them on mullions, and transoms, and labels--for our work was in the old english style--a style in which i had no previous practice. i was diligent, however, and kept old john fraser's principle in view (though, as nature had been less liberal in imparting the necessary faculties, i could not cut so directly as he used to do on the required planes and curves inclosed in the stones); and i had the satisfaction of finding, when pay-night came round, that the foreman, who had frequently stood beside me during the week to observe my modes of working, and the progress which i made, estimated my services at the same rate as he did those of the others. i was by and by intrusted, too, like the best of them, with all the more difficult kinds of work required in the erection, and was at one time engaged for six weeks together in fashioning long, slim, deeply-moulded mullions, not one of which broke in my hands, though the stone on which i wrought was brittle and gritty, and but indifferently suited for the nicer purposes of the architect. i soon found, however, that most of my brother workmen regarded me with undisguised hostility and dislike, and would have been better pleased had i, as they seemed to expect, from the northern locality in which i had been reared, broken down in the trial. i was, they said, "a highlander newly come to scotland," and, if not chased northwards again, would carry home with me half the money of the country. some of the builders used to criticize very unfairly the workmanship of the stones which i hewed: they could not lay them, they said; and the hewers sometimes refused to assist me in carrying in or in turning the weightier blocks on which i wrought. the foreman, however, a worthy, pious man, a member of a secession congregation, stood my friend and encouraged me to persevere. "do not," he has said, "suffer yourself to be driven from the work, and they will soon tire out, and leave you to pursue your own course. i know exactly the nature of your offence: you do not drink with them or treat them; but they will soon cease to expect that you should; and when once they find that you are not to be coerced or driven off, they will let you alone." as, however, from the abundance of employment--a consequence of the building mania--the men were masters and more at the time, the foreman could not take my part openly in opposition to them; but i was grateful for his kindness, and felt too thoroughly indignant at the mean fellows who could take such odds against an inoffensive stranger, to be much in danger of yielding to the combination. it is only a weak man whom the wind deprives of his cloak: a man of the average strength is more in danger of losing it when assailed by the genial beams of a too kindly sun. i threw myself, as usual, for the compensatory pleasures, on my evening walks, but found the enclosed state of the district, and the fence of a rigorously-administered trespass-law, serious drawbacks; and ceased to wonder that a thoroughly cultivated country is, in most instances, so much less beloved by its people than a wild and open one. rights of proprietorship may exist equally in both; but there is an important sense in which the open country belongs to the proprietors and to the people too. all that the heart and the intellect can derive from it may be alike free to peasant and aristocrat; whereas the cultivated and strictly fenced country belongs usually, in every sense, to only the proprietor; and as it is a much simpler and more obvious matter to love one's country as a scene of hills, and streams, and green fields, amid which nature has often been enjoyed, than as a definite locality, in which certain laws and constitutional privileges exist, it is rather to be regretted than wondered at that there should be often less true patriotism in a country of just institutions and equal laws, whose soil has been so exclusively appropriated as to leave only the dusty high-roads to its people, than in wild open countries, in which the popular mind and affections are left free to embrace the soil, but whose institutions are partial and defective. were our beloved monarch to regard such of the gentlemen of her court as taboo their glen tilts, and shut up the passes of the grampians, as a sort of disloyal destructives of a peculiar type, who make it their vocation to divest her people of their patriotism, and who virtually teach them that a country no longer theirs is not worth the fighting for, it might be very safely concluded that she was but manifesting, in one other direction, the strong good sense which has ever distinguished her. though shut out, however, from the neighbouring fields and policies, the niddry woods were open to me; and i have enjoyed many an agreeable saunter along a broad planted belt, with a grassy path in the midst, that forms their southern boundary, and through whose long vista i could see the sun sink over the picturesque ruins of craigmillar castle. a few peculiarities in the natural history of the district showed me, that the two degrees of latitude which lay between me and the former scenes of my studies were not without their influence on both the animal and vegetable kingdoms. the group of land-shells was different, in at least its proportions; and one well-marked mollusc--the large tortoise-shell helix (_helix aspersa_), very abundant in this neighbourhood--i had never seen in the north at all. i formed, too, my first acquaintance in this woody, bush-skirted walk, with the hedgehog in its wild state--an animal which does not occur to the north of the moray firth. i saw, besides, though the summer was of but the average warmth, the oak ripening its acorns--a rare occurrence among the cromarty woods, where, in at least nine out of every ten seasons, the fruit merely forms and then drops off. but my researches this season lay rather among fossils than among recent plants and animals. i was now for the first time located on the carboniferous system: the stone at which i wrought was intercalated among the working coal-seams, and abounded in well-marked impressions of the more robust vegetables of the period--stigmaria, sigillaria, calamites, and lepidodendra; and as they greatly excited my curiosity i spent many an evening hour in the quarry in which they occurred, in tracing their forms in the rock; or, extending my walks to the neighbouring coal pits, i laid open with my hammer, in quest of organisms, the blocks of shale or stratified clay raised from beneath by the miner. there existed at the time none of those popular digests of geological science which are now so common; and so i had to grope my way without guide or assistant, and wholly unfurnished with a vocabulary. at length, however, by dint of patient labour, i came to form not very erroneous, though of course inadequate, conceptions of the ancient coal measure flora: it was impossible to doubt that its numerous ferns were really such; and though i at first failed to trace the supposed analogies of its lepidodendra and calamites, it was at least evident that they were the bole-like stems of great plants, that had stood erect like trees. a certain amount of fact, too, once acquired, enabled me to assimilate to the mass little snatches of information, derived from chance paragraphs and occasional articles in magazines and reviews, that, save for my previous acquaintance with the organisms to which they referred, would have told me nothing. and so the vegetation of the coal measures began gradually to form within my mind's eye, where all had been blank before, as i had seen the spires and columns of edinburgh forming amid the fog, on the morning of my arrival. i found, however, one of the earliest dreams of my youth curiously mingling with my restorations, or rather forming their groundwork. i had read gulliver at the proper age; and my imagination had become filled with the little men and women, and retained strong hold of at least one scene laid in the country of the very tall men--that in which the traveller, after wandering amid grass that rose twenty feet over his head, lost himself in a vast thicket of barley forty feet high. i became the owner, in fancy, of a colony of liliputians, that manned my eighteen-inch canoe, or tilled my apron-breadth of a garden; and, coupling with the men of liliput the scene in brobdignag, i had often set myself to imagine, when playing truant on the green slopes of the hill, or among the swamps of the "willows," how some of the vignette-like scenes by which i was surrounded would have appeared to creatures so minute. i have imagined them threading their way through dark forests of bracken forty feet high--or admiring on the hill-side some enormous club-moss that stretched out its green hairy arms for whole roods--or arrested at the edge of some dangerous morass, by hedges of gigantic horse-tail, that bore a-top, high over the bog, their many-windowed, club-like cones, and at every point shot forth their green verticillate leaves, huge as coach-wheels divested of the rim. and while i thus dreamed for my liliputian companions, i became for the time a liliputian myself, examined the minute in nature as if through a magnifying-glass, roamed in fancy under ferns that had shot up into trees, and saw the dark club-like heads of the equisetaceæ stand up over the spiky branches, some six yards or so above head. and now, strange to tell, i found i had just to fall back on my old juvenile imaginings, and to form my first approximate conceptions of the forests of the coal measures, by learning to look at our ferns, club-mosses, and equisetaceæ, with the eye of some wandering traveller of liliput lost amid their entanglements. when sauntering at sunset along the edge of a wood-embosomed stream that ran through the grounds, and beside which the horse-tail rose thick and rank in the danker hollows, and the bracken shot out its fronds from the drier banks, i had to sink in fancy as of old into a manikin of a few inches, and to see intertropical jungles in the tangled grasses and thickly-interlaced equisetaceæ, and tall trees in the brake and the lady-fern. but many a wanting feature had to be supplied, and many an existing one altered. amid forests of arboraceous ferns, and of horse-tails tall as the masts of pinnaces, there stood up gigantic club-mosses, thicker than the body of a man, and from sixty to eighty feet in height, that mingled their foliage with strange monsters of the vegetable world, of types no longer recognisable among the existing forms--sculptured ullodendra, bearing rectilinear stripes of sessile cones along their sides--and ornately tatooed sigillaria, fluted like columns, and with vertical rows of leaves bristling over their stems and larger branches. such were some of the dreams in which i began at this period for the first time to indulge; nor have they, like the other dreams of youth, passed away. the aged poet has not unfrequently to complain, that as he rises in years, his "visions float less palpably before him." those, on the contrary, which science conjures up, grow in distinctness, as, in the process of slow acquirement, form after form is evoked from out the obscurity of the past, and one restoration added to another. there were at this time several collier villages in the neighbourhood of edinburgh, which have since disappeared. they were situated on what were called the "edge-coals"--those steep seams of the mid-lothian coal basin which, lying low in the system, have got a more vertical tilt against the trap eminences of the south and west than the upper seams in the middle of the field, and which, as they could not be followed in their abrupt descent beyond a certain depth, are now regarded, for at least the practical purposes of the miner, and until the value of coal shall have risen considerably, as wrought out. one of these villages, whose foundations can no longer be traced, occurred in the immediate vicinity of niddry mill. it was a wretched assemblage of dingy, low-roofed, tile-covered hovels, each of which perfectly resembled all the others, and was inhabited by a rude and ignorant race of men, that still bore about them the soil and stain of recent slavery. curious as the fact may seem, all the older men of that village, though situated little more than four miles from edinburgh, had been born slaves. nay, eighteen years later (in ), when parliament issued a commission to inquire into the nature and results of female labour in the coal-pits of scotland, there was a collier still living that had never been twenty miles from the scottish capital, who could state to the commissioners that both his father and grandfather had been slaves--that he himself had been born a slave--and that he had wrought for years in a pit in the neighbourhood of musselburgh ere the colliers got their freedom. father and grandfather had been parishioners of the late dr. carlyle of inveresk. they were cotemporary with chatham and cowper, and burke and fox; and at a time when granville sharpe could have stepped forward and effectually protected the runaway negro who had taken refuge from the tyranny of his master in a british port, no man could have protected _them_ from the inveresk laird, their proprietor, had they dared to exercise the right, common to all britons besides, of removing to some other locality, or of making choice of some other employment. strange enough, surely, that so entire a fragment of the barbarous past should have been thus dovetailed into the age not yet wholly passed away! i regard it as one of the more singular circumstances of my life, that i should have conversed with scotchmen who had been born slaves. the collier women of this village--poor over-toiled creatures, who carried up all the coal from underground on their backs, by a long turnpike stair inserted in one of the shafts--continued to bear more of the marks of serfdom still about them than even the men. how these poor women did labour, and how thoroughly, even at this time, were they characterized by the slave nature! it has been estimated by a man who knew them well--mr. robert bald--that one of their ordinary day's work was equal to the carrying of a hundredweight from the level of the sea to the top of ben lomond. they were marked by a peculiar type of mouth, by which i learned to distinguish them from all the other females of the country. it was wide, open, thick-lipped, projecting equally above and below, and exactly resembled that which we find in the prints given of savages in their lowest and most degraded state, in such narratives of our modern voyagers as, for instance, the "narrative of captain fitzroy's second voyage of the beagle." during, however, the lapse of the last twenty years this type of mouth seems to have disappeared in scotland. it was accompanied by traits of almost infantile weakness. i have seen these collier women crying like children, when toiling under their load along the upper rounds of the wooden stair that traversed the shaft; and then returning, scarce a minute after, with the empty creel, singing with glee. the collier houses were chiefly remarkable for being all alike, outside and in; all were equally dingy, dirty, naked, and uncomfortable. i first learned to suspect, in this rude village, that the democratic watchword, "liberty and equality," is somewhat faulty in its philosophy. slavery and equality would be nearer the mark. wherever there is liberty, the original differences between man and man begin to manifest themselves in their external circumstances, and the equality straightway ceases. it is through slavery that equality, among at least the masses, is to be fully attained.[ ] i found but little intelligence in the neighbourhood, among even the villagers and country people, that stood on a higher platform than the colliers. the fact may be variously accounted for; but so it is, that though there is almost always more than the average amount of knowledge and acquirement amongst the mechanics of large towns, the little hamlets and villages by which they are surrounded are usually inhabited by a class considerably below the average. in m. quetelet's interesting "treatise on man," we find a series of maps given, which, based on extensive statistical tables, exhibit by darker and lighter shadings the moral and intellectual character of the people in the various districts of the countries which they represent. in one map, for instance, representative of the state of education in france, while certain well-taught provinces are represented by a bright tint, as if enjoying the light, there are others, in which great ignorance obtains, that exhibit a deep shade of blackness, as if a cloud rested over them; and the general aspect of the whole is that of a landscape seen from a hill-top in a day of dappled light and shadow. there are certain minuter shadings, however, by which certain curious facts might be strikingly represented to the eye in this manner, for which statistical tables furnish no adequate basis, but which men who have seen a good deal of the people of a country might be able to give in a manner at least approximately correct. in a shaded map representative of the intelligence of scotland, i would be disposed--sinking the lapsed classes, or representing them merely by a few such dark spots as mottle the sun--to represent the large towns as centres of focal brightness; but each of these focal centres i would encircle with a halo of darkness considerably deeper in shade than the medium spaces beyond. i found that in the tenebrious halo of the scottish capital there existed, independently of the ignorance of the poor colliers, three distinct elements. a considerable proportion of the villagers were farm-servants in the decline of life, who, unable any longer to procure, as in their days of unbroken strength, regular engagements from the farmers of the district, supported themselves as occasional labourers. and they, of course, were characterized by the ignorance of their class. another portion of the people were carters--employed mainly, in these times, ere the railways began, in supplying the edinburgh coal-market, and in driving building materials into the city from the various quarries. and carters as a class, like all who live much in the society of horses, are invariably ignorant and unintellectual. a third, but greatly smaller portion than either of the other two, consisted of mechanics; but it was only mechanics of an inferior order, that remained outside the city to work for carters and labourers: the better skilled, and, as to a certain extent the terms are convertible, the more intelligent mechanics found employment and a home in edinburgh. the cottage in which i lodged was inhabited by an old farm-servant--a tall, large-bodied, small-headed man, who, in his journey through life, seemed to have picked up scarce an idea; and his wife, a woman turned of sixty, though a fine enough _body_ in the main, and a careful manager, was not more intellectual. they had but a single apartment in their humble dwelling, fenced off by a little bit of partition from the outer door--and i could fain have wished that they had two--but there was no choice of lodgings in the village, and i had just to content myself, as the working man always must in such circumstances, with the shelter i could get. my bed was situated in the one end of the room, and my landlady's and her husband's in the other, with the passage by which we entered between; but decent old peggy russel had been accustomed to such arrangements all her life long, and seemed never once to think of the matter; and--as she had reached that period of life at which women of the humbler class assume the characteristics of the other sex, somewhat, i suppose, on the principle on which very ancient female birds put on male plumage--i in a short time ceased to think of it also. it is not the less true, however, that the purposes of decency demand that much should be done, especially in the southern and midland districts of scotland, for the dwellings of the poor. footnotes: [ ] uncle james would scarce have sanctioned, had he been consulted in the matter, the use to which the carcase of his dead eagle was applied. there lived in the place an eccentric, half-witted old woman, who, for the small sum of one halfpenny, used to fall a-dancing on the street to amuse children, and rejoiced in the euphonious though somewhat obscure appellation of "dribble drone." some young fellows, on seeing the eagle divested of its skin, and looking remarkably clean and well-conditioned, suggested that it should be sent to "dribble;" and, accordingly, in the character of a "great goose, the gift of a gentleman," it was landed at her door. the gift was thankfully accepted. dribble's cottage proved odoriferous at dinner-time for the several following days; and when asked, after a week had gone by, how she had relished the great goose which the gentleman had seat, she replied, that it was "unco sweet, but oh! teuch, teuch!" for years after, the reply continued to be proverbial in the place: and many a piece of over-hard stock-fish, and over-fresh steak, used to be characterized as, "like dribble drone's eagle, unco sweet, but oh! teuch, teuch!" [ ] well known as gilfillan's song is among ourselves, it is much less so to the south of the border, and i present it to my english readers, as a worthy representative, in these latter days, of those ludicrous songs of our country in the olden time which are so admirably suited to show, notwithstanding the gibe of goldsmith, "that a scot may have humour, i almost said wit." the tax-gatherer. oh! do you ken peter, the taxman an' writer? ye're well aff wha ken naething 'bout him ava; they ca' him inspector, or poor's rate collector-- my faith! he's weel kent in leith, peter m'craw! he ca's and he comes again--haws, and he hums again-- he's only ae hand, but it's as good as twa; he pu's't out and raxes, an' draws in the taxes, an' pouches the siller--shame! peter m'craw! he'll be at your door by daylight on a monday, on tyesday ye're favoured again wi' a ca'; e'en a slee look he gied me at kirk the last sunday, whilk meant--"_mind the preachin' an' peter m'craw._" he glowrs at my auld door as if he had made it; he keeks through the keyhole when i am awa'; he'll syne read the auld stane, that tells a' wha read it, to "_blisse god for a' giftes_,"[*]--but peter m'craw! his sma' papers neatly are 'ranged a' completely, that yours, for a wonder, 's the first on the raw! there's nae jinkin' peter, nae antelope's fleeter; nae _cuttin_' acquaintance wi' peter m'craw! 'twas just friday e'enin', auld reekie i'd been in, i'd gatten a shillin'--i maybe gat twa; i thought to be happy wi' friends ower a drappie, when wha suld come papin--but peter m'craw? there's houp o' a ship though she's sair pressed wi' dangere, an' roun' her frail timmers the angry winds blaw; i've aften gat kindness unlocked for frae strangers, but wha need houp kindness frae peter m'craw? i've kent a man pardoned when just at the gallows-- i've kent a chiel honest whase trade was the law! i've kent fortune's smile even fa' on gude fallows; but i ne'er kent exception wi' peter m'craw! our toun, yince sae cheerie, is dowie an' eerie; our shippies hae left us, our trade is awa'; there's nae fair maids strayin', nae wee bairnies playin; ye've muckle to answer for, peter m'craw! but what gude o' greevin' as lang's we are leevin'? my banes i'll soon lay within yon kirk-yard wa'; there nae care shall press me, nae taxes distress me, for there i'll be free frae thee--peter m'craw! [*]a devout legend, common in the seventeenth century above the entrance of houses. [ ] the act for manumitting our scotch colliers was passed in the year , forty-nine years prior to the date of my acquaintance with the class at niddry. but though it was only such colliers of the village as were in their fiftieth year when i knew them (with, of course, all the older ones), who had been born slaves, even its men of thirty had actually, though not nominally, come into the world in a state of bondage, in consequence of certain penalties attached to the emancipating act, of which the poor ignorant workers under ground were both too improvident and too little ingenious to keep clear. they were set free, however, by a second act passed in . the language of both these acts, regarded as british ones of the latter half of the last century, and as bearing reference to british subjects living within the limits of the island, strikes with startling effect. "whereas," says the preamble of the older act--that of --"by the statute law of scotland, as explained by the judges of the courts of law there, many colliers, and coal-bearers, and salters, are in a state of _slavery or bondage_, bound to the collieries or salt-works where they work _for life, transferable with the collieries and salt-works_; and whereas the emancipating," &c. &c. a passage in the preamble of the act of is scarce less striking: it declares that, notwithstanding the former act, "many colliers and coal-bearers _still continue in a state of bondage_" in scotland. the history of our scotch colliers will be found a curious and instructive one. their slavery seems not to have been derived from the ancient tunes of general serfship, but to have originated in comparatively modern acts of the scottish parliament, and in decisions of the court of session--in acts of a parliament in which the poor ignorant subterranean men of the country were, of course, wholly unrepresented, and in decisions of a court in which no agent of theirs ever made appearance in their behalf. chapter xv. "see inebriety, her wand she waves, and lo! her pale and lo! her purple slaves."--crabbe. i was joined in the course of a few weeks, in peggy russel's one-roomed cottage, by another lodger--lodgers of the humbler class usually consociating together in pairs. my new companion had lived for some time, ere my arrival at niddry, in a neighbouring domicile, which, as he was what was termed a "quiet-living man," and as the inmates were turbulent and unsteady, he had, after bearing a good deal, been compelled to quit. like our foreman, he was a strict seceder, in full communion with his church. though merely a common labourer, with not more than half the wages of our skilled workmen, i had observed, ere our acquaintance began, that no mason in the squad was more comfortably attired on week-days than he, or wore a better suit on sunday; and so i had set him down, from the circumstance, as a decent man. i now found that, like my uncle sandy, he was a great reader of good books--an admirer even of the same old authors--deeply read like him, in durham and rutherford--and entertaining, too, a high respect for baxter, boston, old john brown, and the erskines. in one respect, however, he differed from both my uncles: he had begun to question the excellence of religious establishments; nay, to hold that the country might be none the worse were its ecclesiastical endowments taken away--a view which our foreman also entertained; whereas both uncles sandy and james were as little averse as the old divines themselves to a state-paid ministry, and desiderated only that it should be a good one. there were two other seceders engaged as masons at the work--more of the polemical and less of the devout type than the foreman or my new comrade the labourer; and they also used occasionally to speak, not merely of the doubtful usefulness, but--as they were stronger in their language than their more self-denying and more consistent co-religionists--of the positive worthlessness of establishments. the voluntary controversy did not break out until about nine years after this time, when the reform bill gave vent to many a pent-up opinion and humour among that class to which it extended the franchise; but the materials of the war were evidently already accumulating among the intelligent dissenters of scotland; and from what i now saw, its first appearance in a somewhat formidable aspect failed to take me by surprise. i must in justice add, that all the religion of our party was to be found among its seceders. our other workmen were really wild fellows, most of whom never entered a church. a decided reaction had already commenced within the establishment, on the cold, elegant, unpopular moderatism of the previous period--that moderatism which had been so adequately represented in the scottish capital by the theology of blair and the ecclesiastical policy of robertson; but it was chiefly among the middle and upper classes that the reaction had begun; and scarce any portion of the humbler people, lost to the church during the course of the two preceding generations, had yet been recovered. and so the working men of edinburgh and its neighbourhood, at this time, were in large part either non-religious, or included within the independent or secession pale. john wilson--for such was the name of my new comrade--was a truly good man--devout, conscientious, friendly--not highly intellectual, but a person of plain good sense, and by no means devoid of general information. there was another labourer at the work, an unhappy little man, with whom i have often seen john engaged in mixing mortar, or carrying materials to the builders, but never without being struck by the contrast which they presented in character and appearance. john was a plain, somewhat rustic-looking personage; and an injury which he had received from gunpowder in a quarry, that had destroyed the sight of one of his eyes, and considerably dimmed that of the other, had, of course, not served to improve his looks; but he always wore a cheerful, contented air; and, with all his homeliness, was a person pleasant to the sight. his companion was a really handsome man--grey-haired, silvery-whiskered, with an aristocratic cast of countenance, that would have done no discredit to a royal drawing-room, and an erect though somewhat petit figure, cast in a mould that, if set off more to advantage, would have been recognised as elegant. but john lindsay--for so he was called--bore always the stamp of misery on his striking features. there lay between the poor little man and the crawford peerage only a narrow chasm, represented by a missing marriage certificate; but he was never able to bridge the gulf across; and he had to toil on in unhappiness, in consequence, as a mason's labourer. i have heard the call resounding from the walls twenty times a day--"john, yearl crafurd, bring us anither hod o' lime." i found religion occupying a much humbler place among these workmen of the south of scotland than that which i had used to see assigned to it in the north. in my native district and the neighbouring counties, it still spoke with authority; and a man who stood up in its behalf in any society, unless very foolish or very inconsistent, always succeeded in silencing opposition, and making good its claims. here, however, the irreligious asserted their power as the majority, and carried matters with a high hand; and religion itself, existing as but _dissent_, not as an _establishment_, had to content itself with bare toleration. remonstrance, or even advice, was not permitted. "johnnie, boy," i have heard one of the rougher mechanics say, half in jest, half in earnest, to my companion, "if you set yourself to convert me, i'll brak your face;" and i have known another of them remark, with a patronizing air, that "kirks werena very bad things, after a';" that he "aye liked to be in a kirk, for the sake of decency, once a twelvemonth;" and that, as he "hadna been kirked for the last ten months, he was just only waiting for a rainy sabbath, to lay in his stock o' divinity for the year." our new lodger, aware how little any interference with the religious concerns of others was tolerated in the place, seemed unable for some time to muster up resolution enough to broach in the family his favourite subject. he retired every night, before going to bed, to his closet--the blue vault, with all its stars--often the only closet of the devout lodger in a south-country cottage; but i saw that each evening, ere he went out, he used to look uneasily at the landlord and me, as if there lay some weight on his mind regarding us, of which he was afraid to rid himself, and which yet rendered him very uncomfortable. "well, john," i asked one evening, speaking direct, to his evident embarrassment; "what is it?" john looked at old william the landlord, and then at me. "did we not think it right," he said, "that there should be evening worship in the family?" old william had not idea enough for conversation: he either signified acquiescence in whatever was said that pleased him, by an ever-recurring ay, ay, ay; or he grumbled out his dissent in a few explosive sounds, that conveyed his meaning rather in their character as tones than as vocables. but there now mingled with the ordinary explosions the distinct enunciation, given with, for him, unwonted emphasis, that he "wasna for _that_." i struck in, however, on the other side, and appealed to peggy. "i was sure," i said, "that mrs. russel would see the propriety of john's proposal." and mrs. russel, as most women would have done in the circumstances, unless, indeed, very bad ones, did see the propriety of it; and from that evening forward the cottage had its family worship. john's prayers were always very earnest and excellent, but sometimes just a little too long; and old william, who, i fear, did not greatly profit by them, used not unfrequently to fall asleep on his knees. but though he sometimes stole to his bed when john chanced to be a little later in taking the book than usual, and got into a profound slumber ere the prayer began, he deferred to the majority, and gave us no active opposition. he was not a vicious man: his intellect had slept through life, and he had as little religion as an old horse or dog; but he was quiet and honest, and, to the measure of his failing ability, a faithful worker in his humble employments. his religious training, like that of his brother villagers, seemed to have been sadly neglected. had he gone to the parish church on sunday, he would have heard a respectable moral essay read from the pulpit, and would, of course, have slept under it; but william, like most of his neighbours, preferred sleeping out the day at home, and never did go to the church; and as certainly as he went not to the teacher of religion, the teacher of religion never came to him. during the ten months which i spent in the neighbourhood of niddry mill, i saw neither minister nor missionary. but if the village furnished no advantageous ground on which to fight the battle of religious establishments--seeing that the establishment was of no manner of use there--it furnished ground quite as unsuitable for the class of voluntaries who hold that the supply of religious instruction should, as in the case of all other commodities, be regulated by the demand. demand and supply were admirably well balanced in the village of niddry: there was no religious instruction, and no wish or desire for it. the masons at niddry house were paid fortnightly, on a saturday night. wages were high--we received two pounds eight shillings for our two weeks' work; but scarce half-a-dozen in the squad could claim at settlement the full tale, as the monday and tuesday after pay-night were usually blank days, devoted by two-thirds of the whole to drinking and debauchery. not often have wages been more sadly mis-spent than by my poor work-fellows at niddry, during this period of abundant and largely-remunerated employment. on receiving their money, they set straightway off to edinburgh, in parties of threes and fours; and until the evening of the following monday or tuesday i saw no more of them. they would then come dropping in, pale, dirty, disconsolate-looking--almost always in the reactionary state of unhappiness which succeeds intoxication--(they themselves used to term it "_the horrors_")--and with their nervous system so shaken, that rarely until a day or two after did they recover their ordinary working ability. narratives of their adventures, however, would then begin to circulate through the squad--adventures commonly of the "tom and jerry" type; and always, the more extravagant they were, the more was the admiration which they excited. on one occasion, i remember (for it was much spoken about as a manifestation of high spirit) that three of them, hiring a coach, drove out on the sunday to visit roslin and hawthornden, and in this way spent their six pounds so much in the style of gentlemen, that they were able to get back to the mallet without a farthing on the evening of monday. and, as they were at work on tuesday in consequence, they succeeded, as they said, in saving the wages of a day usually lost, just by doing the thing so genteelly. edinburgh had in those times a not very efficient police, and, in some of its less reputable localities, must have been dangerous. burke found its west port a fitting scene for his horrid trade a good many years after; and from the stories of some of our bolder spirits, which, though mayhap exaggerated, had evidently their nucleus of truth, there was not a little of the violent and the lawless perpetrated in its viler haunts during the years of the speculation mania. four of our masons found, one saturday evening, a country lad bound hand and foot on the floor of a dark inner room in one of the dens of the high street; and such was the state of exhaustion to which he was reduced, mainly through the compression of an old apron wrapped tightly round his face, that though they set him loose, it was some time ere he could muster strength enough to crawl away. he had been robbed by a bevy of women whom he had been foolish enough to treat; and on threatening to call in the watchman, they had fallen upon a way of keeping him quiet, which, save for the interference of my wild fellow-workmen, would soon have rendered him permanently so. and such was but one of many stories of the kind. there was of course a considerable diversity of talent and acquirement among my more reckless associates at the work; and it was curious enough to mark their very various views regarding what constituted spirit or the want of it. one weak lad used to tell us about a singularly spirited brother apprentice of his, who not only drank, kept loose company, and played all sorts of very mischievous practical jokes, but even occasionally stole, out of warehouses; which was of course a very dauntless thing, seeing that it brought him within wind of the gallows; whereas another of our wild workmen--a man of sense and intelligence--not unfrequently cut short the narratives of the weaker brother, by characterizing his spirited apprentice as a mean, graceless scamp, who, had he got his deservings, would have been hung like a dog. i found that the intelligence which results from a fair school education, sharpened by a subsequent taste for reading, very much heightened in certain items the standard by which my comrades regulated their conduct. mere intelligence formed no guard amongst them against intemperance or licentiousness; but it did form a not ineffectual protection against what are peculiarly the mean vices--such as theft, and the grosser and more creeping forms of untruthfulness and dishonesty. of course, exceptional cases occur in all grades of society: there have been accomplished ladies of wealth and rank who have indulged in a propensity for stealing out of drapers' shops; and gentlemen of birth and education who could not be trusted in a library or a bookseller's back-room; and what sometimes occurs in the higher walks must be occasionally exemplified in the lower also; but, judging from what i have seen, i must hold it as a general rule, that a good intellectual education is a not inefficient protection against the meaner felonies, though not in any degree against the "pleasant vices." the only adequate protection against both, equally, is the sort of education which my friend john wilson the labourer exemplified--a kind of education not often acquired in schools, and not much more frequently possessed by schoolmasters than by any other class of professional men. the most remarkable man in our party was a young fellow of three-and-twenty--at least as much a blackguard as any of his companions, but possessed of great strength of character and intellect, and, with all his wildness, marked by very noble traits. he was a strongly and not inelegantly formed man, of about six feet--dark-complexioned, and of a sullen cast of countenance, which, however, though he could, i doubt not, become quite as formidable as he looked, concealed in his ordinary moods much placidity of temper, and a rich vein of humour. charles ---- was the recognised hero of the squad; but he differed considerably from the men who admired him most. burns tells us that he "often courted the acquaintance of the part of mankind commonly known by the ordinary phrase of _blackguards_;" and that, "though disgraced by follies, nay, sometimes stained with guilt, he had yet found among them, in not a few instances, some of the noblest virtues--magnanimity, generosity, disinterested friendship, and even modesty." i cannot say with the poet that i ever courted the acquaintance of blackguards; but though the labouring man may select his friends, he cannot choose his work-fellows; and so i have not unfrequently _come in contact_ with blackguards, and have had opportunities of pretty thoroughly knowing them. and my experience of the class has been very much the reverse of that of burns. i have usually found their virtues of a merely theatric cast, and their vices real; much assumed generosity in some instances, but a callousness of feeling, and meanness of spirit, lying concealed beneath. in this poor fellow, however, i certainly did find a sample of the nobler variety of the genus. poor charles did too decidedly belong to it. he it was that projected the sunday party to roslin; and he it was that, pressing his way into the recesses of a disreputable house in the high street, found the fast-bound wight choking in an apron, and, unloosing the cords, let him go. no man of the party squandered his gains more recklessly than charles, or had looser notions regarding the legitimacy of the uses to which he too often applied them. and yet, notwithstanding, he was a generous-hearted fellow; and, under the influence of religious principle, would, like burns himself, have made a very noble man. in gradually forming my acquaintance with him, i was at first struck by the circumstance that he never joined in the clumsy ridicule with which i used to be assailed by the other workmen. when left, too, on one occasion, in consequence of a tacit combination against me, to roll up a large stone to the sort of block-bench, or _siege_, as it is technically termed, on which the mass had to be hewn, and as i was slowly succeeding in doing, through dint of very violent effort, what some two or three men usually united to do, charles stepped out to assist me; and the combination at once broke down. unlike the others, too, who, while they never scrupled to take odds against me, seemed sufficiently chary of coming in contact with me singly, he learned to seek me out in our intervals of labour, and to converse on subjects upon which we felt a common interest. he was not only an excellent operative mechanic, but possessed also of considerable architectural skill; and in this special province we found an interchange of idea not unprofitable. he had a turn, too, for reading, though he was by no means extensively read; and liked to converse about books. nor, though the faculty had been but little cultivated, was he devoid of an eye for the curious in nature. on directing his attention, one morning, to a well-marked impression of lepidodendron, which delicately fretted with its lozenge-shaped network one of the planes of the stone before me, he began to describe, with a minuteness of observation not common among working men, certain strange forms which had attracted his notice when employed among the grey flagstones of forfarshire. i long after recognised in his description that strange crustacean of the middle old red sandstone of scotland, the _pterygotus_--an organism which was wholly unknown at this time to geologists, and which is but partially known still; and i saw in , on the publication, in its first edition, of the "elements" of sir charles lyell, what he meant to indicate, by a rude sketch which he drew on the stone before us, and which, to the base of a semi-ellipsis, somewhat resembling a horse-shoe, united an angular prolongation not very unlike the iron stem of a pointing trowel drawn from the handle. he had evidently seen, long ere it had been detected by the scientific eye, that strange ichthyolite of the old red system, the _cephalaspis_. his story, though he used to tell it with great humour, and no little dramatic effect, was in reality a very sad one. he had quarrelled, when quite a lad, with one of his fellow-workmen, and was unfortunate enough, in the pugilistic encounter which followed, to break his jawbone, and otherwise so severely to injure him, that for some time his recovery seemed doubtful. flying, pursued by the officers of the law, he was, after a few days' hiding, apprehended, lodged in jail, tried at the high court of justiciary, and ultimately sentenced to three months' imprisonment. and these three months he had to spend--for such was the wretched arrangement of the time--in the worst society in the world. in sketching, as he sometimes did, for the general amusement, the characters of the various prisoners with whom he had associated--from the sneaking pick-pocket and the murderous ruffian, to the simple highland smuggler, who had converted his grain into whisky, with scarce intelligence enough to see that there was aught morally wrong in the transaction--he sought only to be as graphic and humorous as he could, and always with complete success. but there attached to his narratives an unintentional moral; and i cannot yet call them up without feeling indignant at that detestable practice of promiscuous imprisonment which so long obtained in our country, and which had the effect of converting its jails into such complete criminal-manufacturing institutions, that, had the honest men of the community risen and dealt by them as the lord-george-gordon mob dealt with newgate, i hardly think they would have been acting out of character. poor charles had a nobility in his nature which saved him from being contaminated by what was worst in his meaner associates; but he was none the better for his imprisonment, and he quitted jail, of course, a marked man; and his after career was, i fear, all the more reckless in consequence of the stain imparted at this time to his character. he was as decidedly a leader among his brother workmen as i myself had been, when sowing my wild oats, among my schoolfellows; but society in its settled state, and in a country such as ours, allows no such scope to the man as it does to the boy; and so his leadership, dangerous both to himself and his associates, had chiefly as the scene of its trophies the grosser and more lawless haunts of vice and dissipation. his course through life was a sad, and, i fear, a brief one. when that sudden crash in the commercial world took place, in which the speculation mania of - terminated, he was, with thousands more, thrown out of employment; and, having saved not a farthing of his earnings, he was compelled, under the pressure of actual want, to enlist as a soldier into one of the regiments of the line, bound for one of the intertropical colonies. and there, as his old comrades lost all trace of him, he too probably fell a victim, in an insalubrious climate, to old habits and new rum. finding me incorrigible, i was at length left by my brother operatives to be as peculiar as i pleased; and the working portion of the autumnal months passed off pleasantly enough in hewing great stones under the branching foliage of the elm and chestnut trees of niddry park. from the circumstance, however, that the stones were so great, the previous trial had been an embarrassing one; and, though too proud to confess that i cared aught about the matter, i was now glad enough that it was fairly over. our modern temperance societies--institutions which at this time had not begun to exist--have done much to shield sober working men from combinations of the trying character to which, in the generation well-nigh passed away, they were too often exposed. there are few working parties which have not now their groups of enthusiastic teetotallers, that always band together against the drinkers, and mutually assist and keep one another in countenance: and a breakwater is thus formed in the middle of the stream, to protect from that grinding oppression of the poor by the poor, which, let popular agitators declaim on the other side as they may, is at once more trying and more general than the oppression which they experience from the great and wealthy. according to the striking figure of the wise old king, "it is like a sweeping rain, which leaveth no food." fanaticism in itself is not a good thing; nor are there many quiet people who do not dislike enthusiasm; and the members of new sects, whether they be religious sects or no, are almost always enthusiasts, and in some degree fanatical. a man can scarce become a vegetarian even without also becoming in some measure intolerant of the still large and not very disreputable class that eat beef with their greens, and herrings with their potatoes; and the drinkers of water do say rather strong things of the men who, had they been guests at the marriage in cana of galilee, would have seen no great harm in partaking in moderation of the wine. there is a somewhat intolerant fanaticism among the teetotallers, just as there is fanaticism amongst most other new sects; and yet, recognising it simply as strength, and knowing what it has to contend with, i am much disposed to tolerate it, whether _it_ tolerate me or no. human nature, with all its defects, is a wiser thing than the mere common sense of the creatures whose nature it is; and we find in it special provisions, as in the instincts of the humbler animals, for overmastering the special difficulties with which it is its destiny to contend. and the sort of fanaticism to which i refer seems to be one of those provisions. a few teetotallers of the average calibre and strength, who take their stand against the majority in a party of wild dissipated mechanics, would require a considerable amount of vigorous fanaticism to make good their position; nor do i see in ordinary men, as society at present exists, aught at once sufficiently potent in its nature, and sufficiently general in its existence, to take its place and do its work. it seems to subsist in the present imperfect state as a wise provision, though, like other wise provisions, such as the horns of the bull or the sting of the bee, it is misdirected at times, and does harm. winter came on, and our weekly wages were lowered immediately after hallow-day, from twenty-four to fifteen shillings per week. this was deemed too large a reduction; and, reckoning by the weekly hours during which, on the average, we were still able to work--forty-two, as nearly as i could calculate, instead of sixty--it _was_ too great a reduction by about one shilling and ninepence. i would, however, in the circumstances, have taken particular care not to strike work for an advance. i knew that three-fourths of the masons about town--quite as improvident as the masons of our own party--could not live on their resources for a fortnight, and had no general fund to sustain them; and further, that many of the master-builders were not very urgently desirous to press on their work throughout the winter. and so, when, on coming to the work-shed on the monday morning after the close of our first fortnight on the reduced scale, i found my comrades gathered in front of it in a group, and learned that there was a grand strike all over the district, i received the intelligence with as little of the enthusiasm of the "independent associated mechanic" as possibly may be. "you are in the right in your claims," i said to charles; "but you have taken a bad time for urging them, and will be beaten to a certainty. the masters are much better prepared for a strike than you are. how, may i ask, are you yourself provided with the sinews of war?" "very ill indeed," said charles, scratching his head: "if the masters don't give in before saturday, it's all up with me; but never mind; let us have one day's fun: there's to be a grand meeting at bruntsfield links; let us go in as a deputation from the country masons, and make a speech about our rights and duties; and then, if we see matters going very far wrong, we can just step back again, and begin work to-morrow." "bravely resolved," i said: "i shall go with you by all means, and take notes of your speech." we marched into town, about sixteen in number; and, on joining the crowd already assembled on the links, were recognised, by the deep red hue of our clothes and aprons, which differed considerably from that borne by workers in the paler edinburgh stone, as a reinforcement from a distance, and were received with loud cheers. charles, however, did not make his speech: the meeting, which was about eight hundred strong, seemed fully in the possession of a few crack orators, who spoke with a fluency to which he could make no pretensions; and so he replied to the various calls from among his comrades, of "cha, cha," by assuring them that he could not catch the eye of the gentleman in the chair. the meeting had, of course, neither chair nor chairman; and after a good deal of idle speech-making, which seemed to satisfy the speakers themselves remarkably well, but which at least some of their auditory regarded as nonsense, we found that the only motion on which we could harmoniously agree was a motion for an adjournment. and so we adjourned till the evening, fixing as our place of meeting one of the humbler halls of the city. my comrades proposed that we should pass the time until the hour of meeting in a public-house; and, desirous of securing a glimpse of the sort of enjoyment for which they sacrificed so much, i accompanied them. passing not a few more inviting-looking places, we entered a low tavern in the upper part of the canongate, kept in an old half-ruinous building, which has since disappeared. we passed on through a narrow passage to a low-roofed room in the centre of the erection, into which the light of day never penetrated, and in which the gas was burning dimly in a close sluggish atmosphere, rendered still more stifling by tobacco-smoke, and a strong smell of ardent spirits. in the middle of the crazy floor there was a trap-door which lay open at the time; and a wild combination of sounds, in which the yelping of a dog, and a few gruff voices that seemed cheering him on, were most noticeable, rose from the apartment below. it was customary at this time for dram-shops to keep badgers housed in long narrow boxes, and for working men to keep dogs; and it was part of the ordinary sport of such places to set the dogs to unhouse the badgers. the wild sport which scott describes in his "guy mannering," as pursued by dandy dinmont and his associates among the cheviots, was extensively practised twenty-nine years ago amid the dingier haunts of the high street and the canongate. our party, like most others, had its dog--a repulsive-looking brute, with an earth-directed eye, as if he carried about with him an evil conscience; and my companions were desirous of getting his earthing ability tested upon the badger of the establishment; but on summoning the tavern-keeper, we were told that the party below had got the start of us: their dog was as we might hear, "just drawing the badger; and before our dog could be permitted to draw him, the poor brute would require to get an hour's rest." i need scarce say that the hour was spent in hard drinking in that stagnant atmosphere; and we then all descended through the trap-door, by means of a ladder, into a bare-walled dungeon, dark and damp, and where the pestiferous air smelt like that of a burial vault. the scene which followed was exceedingly repulsive and brutal--nearly as much so as some of the scenes furnished by those otter hunts in which the aristocracy of the country delight occasionally to indulge. amid shouts and yells, the badger, with the blood of his recent conflict still fresh upon him, was again drawn to the box mouth; and the party returning satisfied to the apartment above, again betook themselves to hard drinking. in a short time the liquor began to tell, not first, as might be supposed, on our younger men, who were mostly tall, vigorous fellows, in the first flush of their full strength, but on a few of the middle-aged workmen, whose constitutions seemed undermined by a previous course of dissipation and debauchery. the conversation became very loud, very involved, and, though highly seasoned with emphatic oaths, very insipid; and leaving with cha--who seemed somewhat uneasy that my eye should be upon their meeting in its hour of weakness--money enough to clear off my share of the reckoning, i stole out to the king's park, and passed an hour to better purpose among the trap rocks than i could possibly have spent it beside the trap-door. of that tavern party, i am not aware that a single individual save the writer is now living: its very dog did not live out half his days. his owner was alarmed one morning, shortly after this time, by the intelligence that a dozen of sheep had been worried during the night on a neighbouring farm, and that a dog very like his had been seen prowling about the fold; but in order to determine the point, he would be visited, it was added, in the course of the day, by the shepherd and a law-officer. the dog meanwhile, however, conscious of guilt--for dogs do seem to have consciences in such matters--was nowhere to be found, though, after the lapse of nearly a week, he again appeared at the work; and his master, slipping a rope round his neck, brought him to a deserted coal-pit half-filled with water, that opened in an adjacent field, and, flinging him in, left the authorities no clue by which to establish his identity with the robber and assassin of the fold. i had now quite enough of the strike; and, instead of attending the evening meeting, passed the night with my friend william ross. curious to know, however, whether my absence had been observed by my brother workmen, i asked cha, when we next met, "what he thought of _our_ meeting?" "gude-sake!" he replied, "let that flee stick to the wa'! we got upon the _skuff_ after you left us, and grew deaf to time, and so not one of us has seen the meeting yet." i learned, however, that, though somewhat reduced in numbers, it had been very spirited and energetic, and had resolved on nailing the colours to the mast; but in a few mornings subsequent, several of the squads returned to work on their master's terms, and all broke down in about a week after. contrary to what i should have expected from my previous knowledge of him, i found that my friend william ross took a warm interest in strikes and combinations, and was much surprised at the apathy which i manifested on this occasion; nay, that he himself, as he told me, actually officiated as clerk for a combined society of house-painters, and entertained sanguine hopes regarding the happy influence which the principle of union was yet to exercise on the status and comfort of the working man. there are no problems more difficult than those which speculative men sometimes attempt solving, when they set themselves to predict how certain given characters would act in certain given circumstances. in what spirit, it has been asked, would socrates have listened to the address of paul on mars hill, had he lived a few ages later? and what sort of a statesman would robert burns have made? i cannot answer either question; but this i know, that from my intimate acquaintance with the retiring, unobtrusive character of my friend in early life, i should have predicted that he would have taken no interest whatever in strikes or combinations; and i was now surprised to find the case otherwise. and he, on the other hand, equally intimate with my comparatively wild boyhood, and my influence among my schoolfellows, would have predicted that i should have taken a very warm interest in such combinations, mayhap as a ringleader; at all events, as an energetic, influential member; and he was now not a little astonished to see me keeping aloof from them, as things of no account or value. i believe, however, we were both acting in character. lacking my obstinacy, he had in some degree yielded, on first coming to the capital, to the tyranny of his brother workmen; and, becoming one of themselves, and identifying his interest with theirs, his talents and acquirements had recommended him to an office of trust among them; whereas i, stubbornly battling, like harry of the wynd, "for my own hand," would not stir a finger in assertion of the alleged rights of fellows who had no respect for the rights which were indisputably mine. i may here mention, that this first year of the building mania was also the first, in the present century, of those great _strikes_ among workmen, of which the public has since heard and seen so much. up till this time, combination among operatives for the purpose of raising the rate of wages had been a crime punishable by law; and though several combinations and trade unions did exist, open strikes, which would have been a too palpable manifestation of them to be tolerated, could scarce be said ever to take place. i saw enough at the period to convince me, that though the _right_ of combination, abstractly considered, is just and proper, the strikes which would result from it as consequences would be productive of much evil, and little good; and in an argument with my friend william on the subject, i ventured to assure him that his house-painter's union would never benefit the operative house-painters as a class, and urged him to give up his clerkship. "there is a want," i said, "of true leadership among our operatives in these combinations. it is the wilder spirits that dictate the conditions; and, pitching their demands high, they begin usually by enforcing acquiescence in them on the quieter and more moderate among their companions. they are tyrants to their fellows ere they come into collision with their masters, and have thus an enemy in the camp, not unwilling to take advantage of their seasons of weakness, and prepared to rejoice, though secretly mayhap, in their defeats and reverses. and further, their discomfiture will be always quite certain enough when seasons of depression come, from the circumstance that, fixing their terms in prosperous times, they will fix them with reference rather to their present power of enforcing them, than to that medium line of fair and equal adjustment on which a conscientious man could plant his foot and make a firm stand. men such as you, able and ready to work in behalf of these combinations, will of course get the work to do, but you will have little or no power given you in their direction: the direction will be apparently in the hands of a few fluent _gabbers_; and yet even they will not be the actual directors--they will be but the exponents and voices of the general mediocre sentiment and inferior sense of the mass as a whole, and acceptable only so long as they give utterance to that; and so, ultimately, exceedingly little will be won in this way for working men. it is well that they should be allowed to combine, seeing that combination is permitted to those who employ them; but until the majority of our working men of the south become very different from what they now are--greatly wiser and greatly better--there will be more lost than gained by their combinations. according to the circumstances of the time and season, the current will be at one period running in their favour against the masters, and at another in favour of the masters against them: there will be a continual ebb and flow, like that of the sea, but no general advance; and the sooner that the like of you and i get out of the rough conflict and jostle of the tideway, and set ourselves to labour apart on our own internal resources, it will be all the better for us." william, however, did not give up his clerkship; and i daresay the sort of treatment which i had received at the hands of my fellow-workmen made me express myself rather strongly on the subject; but the actual history of the numerous strikes and combinations which have taken place during the quarter of a century and more which has since intervened, is of a kind not in the least suited to modify my views. there _is_ a want of judicious leadership among our working men; and such of the autobiographies of the class as are able and interesting enough to obtain a hearing of their authors show, i am inclined to think, how this takes place. combination is first brought to bear among them against the men, their fellows, who have vigour enough of intellect to think and act for themselves; and such always is the character of the born leader: these true leaders are almost always forced into the opposition; and thus separating between themselves and the men fitted by nature to render them formidable, they fall under the direction of mere chatterers and stump orators, which is in reality no direction at all. the author of the "working man's way in the world"--evidently a very superior man--had, he tells us, to quit at one time his employment, overborne by the senseless ridicule of his brother workmen. somerville states in his autobiography, that, both as a labouring man and a soldier, it was from the hands of his comrades that--save in one memorable instance--he had experienced all the tyranny and oppression of which he had been the victim. nay, benjamin franklin himself was deemed a much more ordinary man in the printing-house in bartholomew close, where he was teased and laughed at as the _water-american_, than in the house of representatives, the royal society, or the court of france. the great printer, though recognised by accomplished politicians as a profound statesman, and by men of solid science as "the most rational of the philosophers," was regarded by his poor brother compositors as merely an odd fellow, who did not conform to their drinking usages, and whom it was therefore fair to tease and annoy as a contemner of the _sacrament_ of the _chapel_.[ ] the life of my friend was, however, pitched on a better and higher tone than that of most of his brother unionists. it was intellectual and moral, and its happier hours were its hours of quiet self-improvement, when, throwing himself on the resources within, he forgot for the time the unions and combinations that entailed upon him much troublesome occupation, but never did him any service. i regretted, however, to find that a distrust of his own powers was still growing upon him, and narrowing his circle of enjoyment. on asking him whether he still amused himself with his flute, he turned, after replying with a brief "o no!" to a comrade with whom he had lived for years, and quietly said to him, by way of explaining the question, "robert, i suppose you don't know i was once a grand flute-player!" and sure enough robert did not know. he had given up, too, his water-colour drawing, in which his taste was decidedly fine; and even in oils, with which he still occasionally engaged himself, instead of casting himself full on nature, as at an earlier period, he had become a copyist of the late rev. mr. thomson of duddingstone, at that time in the full blow of his artistic reputation; nor could i see that he copied him well. i urged and remonstrated, but to no effect. "ah, miller," he has said, "what matters it how i amuse myself? you have stamina in you, and will force your way; but i want strength: the world will never hear of me." that overweening conceit which seems but natural to the young man as a playful disposition to the kitten, or a soft and timid one to the puppy, often assumes a ridiculous, and oftener still an unamiable, aspect. and yet, though it originates many very foolish things, it seems to be in itself, like the fanaticism of the teetotaller, a wise provision, which, were it not made by nature, would leave most minds without spring enough to effect, with the required energy, the movements necessary to launch them fairly into busy or studious life. the sobered man of mature age who has learned pretty correctly to take the measure of himself, has usually acquired both habits and knowledge that assist him in urging his onward way, and the moving force of necessity always presses him onward from behind; but the exhilarating conviction of being born to superior parts, and to do something astonishingly clever, seems necessary to the young man; and when i see it manifesting itself, if not very foolishly or very offensively, i usually think of my poor friend william ross, who was unfortunate enough wholly to want it; and extend to it a pretty ample toleration. ultimately my friend gave up painting, and restricted himself to the ornamental parts of his profession, of which he became very much a master. in finishing a ceiling in oils, upon which he had represented in bold relief some of the ornately sculptured foliage of the architect, the gentleman for whom he wrought (the son-in-law of a distinguished artist, and himself an amateur), called on his wife to admire the truthful and delicate shading of their house-painter. it was astonishing, he said, and perhaps somewhat humiliating, to see the mere mechanic trenching so decidedly on the province of the artist. poor william ross, however, was no mere mechanic; and even artists might have regarded his encroachments on their proper domain with more of complacency than humiliation. one of the last pieces of work upon which he was engaged was a gorgeously painted ceiling in the palace of some irish bishop, which he had been sent all the way from glasgow to finish. every society, however homely, has its picturesque points, nor did even that of the rather commonplace hamlet in which i resided at this time wholly want them. there was a decaying cottage a few doors away, that had for its inmate a cross-tempered old crone, who strove hard to set up as a witch, but broke down from sheer want of the necessary capital. she had been one of the underground workers of niddry in her time; and, being as little intelligent as most of the other collier-women of the neighbourhood, she had not the necessary witch-lore to adapt her pretensions to the capacity of belief which obtained in the district. and so the general estimate formed regarding her was that to which our landlady occasionally gave expression. "donnart auld bodie," peggy used to say; "though she threaps hersel' a witch, she's nae mair witch than i am: she's only just trying, in her feckless auld age, to make folk stand in her reverence." old alie was, however, a curiosity in her way--quite malignant enough to be a real witch, and fitted, if with a few more advantages of acquirement, she had been antedated an age or two, to become as hopeful a candidate for a tar-barrel as most of her class. her next-door neighbour was also an old woman, and well-nigh as poor as the crone; but she was an easy-tempered genial sort of person, who wished harm to no one; and the expression of content that dwelt on her round fresh face, which, after the wear of more than seventy winters, still retained its modicum of colour, contrasted strongly with the fierce wretchedness that gleamed from the sharp and sallow features of the witch. it was evident that the two old women, though placed externally in almost the same circumstances, had essentially a very different lot assigned to them, and enjoyed existence in a very unequal degree. the placid old woman kept a solitary lodger--"davie the apprentice"--a wayward, eccentric lad, much about my own age, though in but the second "year of his time," who used to fret even her temper, and who, after making trial of i know not how many other professions, now began to find that his genius did not lie to the mallet. davie was stage-mad; but for the stage nature seemed to have fitted him rather indifferently: she had given him a squat ungainly figure, an inexpressive face, a voice that in its intonations somewhat resembled the grating of a carpenter's saw; and, withal, no very nice conception of either comic or serious character; but he could recite in the "big bow-wow style," and think and dream of only plays and play-actors. to davie the world and its concerns seemed unworthy of a moment's care, and the stage appeared the only great reality. he was engaged, when i first made his acquaintance, in writing a play, with which he had already filled a whole quire of foolscap, without, however, having quite entered upon the plot; and he read to me some of the scenes in tones of such energy that the whole village heard. though written in the kind of verse which dr. young believed to be the language of angels, his play was sad stuff; and when he paused for my approbation, i ventured to suggest an alteration in one of the speeches. "there, sir," said davie, in the vein of cambyses, "take the pen; let me see, sir, how _you_ would turn it." i accordingly took the pen, and re-wrote the speech. "hum," said davie, as he ran his eye along the lines, "that, sir, is mere poetry. what, think you, could the great kean make of feeble stuff like that? let me tell you, sir, you have no notion whatever of stage effect." i, of course, at once acquiesced; and davie, mollified by my submission, read to me yet another scene. cha, however, of whom he stood a good deal in awe, used to tease him not a little about his play. i have heard him inquire sedulously about the development of the story and the management of the characters, and whether he was writing the several parts with a due eye to the capabilities of the leading actors of the day; and davie, not quite sure, apparently, whether cha was in joke or earnest, was usually on these occasions very chary of reply. davie, had he but the means of securing access, would have walked in every night to the city to attend the playhouse; and it quite astonished him, he used to say, that i, who really knew something of the drama, and had four shillings a day, did not nightly at least devote one of the four to purchase perfect happiness and a seat in the shilling gallery. on some two, or at most three occasions, i did attend the playhouse, accompanied by cha and a few of the other workmen; but though i had been greatly delighted, when a boy, by the acting of a company of strollers that had visited cromarty, and converted the council house hall into a theatre, the greatly better acting of the edinburgh company failed to satisfy me now. the few plays, however, which i saw enacted chanced to be of a rather mediocre character, and gave no scope for the exhibition of nice histrionic talent; nor were any of the great actors of the south on the edinburgh boards at the time. the stage scenery, too, though quite fine enough of its kind, had, i found, altogether a different effect upon me from the one which it had been elaborated to produce. in perusing our fine old dramas, it was the truth of nature that the vividly-drawn scenes and figures, and the happily-portrayed characters, always suggested; whereas the painted canvas, and the respectable but yet too palpable acting, served but to unrealize what i saw, and to remind me that i was merely in a theatre. further, i deemed it too large a price to devote a whole evening to see some play acted which, mayhap, as a composition i would not have deemed worth the reading; and so the temptation of play-going failed to tempt me; and latterly, when my comrades set out for the playhouse, i stayed at home. whatever the nature of the process through which they have gone, a considerable proportion of the more intelligent mechanics of the present generation seem to have landed in conclusions similar to the one at which i at this time arrived. at least, for every dozen of the class that frequented the theatre thirty years ago, there is scarce one that frequents it now. i have said that the scenery of the stage made no very favourable impression upon me. some parts of it must, however, have made a considerably stronger one than i could have supposed at the time. fourteen years after, when the whole seemed to have passed out of memory, i was lying ill of small-pox, which, though a good deal modified apparently by the vaccination of a long anterior period, was accompanied by such a degree of fever, that for two days together one delirious image continued to succeed another in the troubled sensorium, as scene succeeds scene in the box of an itinerant showman. as is not uncommon, however, in such cases, though ill enough to be haunted by the images, i was yet well enough to know that they were idle unrealities, the mere effects of indisposition; and even sufficiently collected to take an interest in watching them as they arose, and in striving to determine whether they were linked together by the ordinary associative ties. i found, however, that they were wholly independent of each other. curious to know whether the will exerted any power over them, i set myself to try whether i could not conjure up a death's-head as one of the series; but what rose instead was a cheerful parlour fire, bearing a-top a tea-kettle, and as the picture faded and then vanished, it was succeeded by a gorgeous cataract, in which the white foam, at first strongly relieved against the dark rock over which it fell, soon exhibited a deep tinge of sulphurous blue, and then came dashing down in one frightful sheet of blood. the great singularity of the vision served to freshen recollection, and i detected in the strange cataract every line and tint of the water-fall in the incantation scene in "der freischütz" which i had witnessed in the theatre royal of edinburgh, with certainly no very particular interest, so long before. there are, i suspect, provinces in the philosophy of mind into which the metaphysicians have not yet entered. of that accessible storehouse in which the memories of past events lie arranged and taped up, they appear to know a good deal; but of a mysterious cabinet of daguerrotype pictures, of which, though fast locked up on ordinary occasions, disease sometimes flings the door ajar, they seem to know nothing. footnote: [ ] the kind of club into which the compositors of a printing-house always form themselves has from time immemorial been termed a _chapel_; and the petty tricks by which franklin was annoyed were said to be played him by the chapel ghost. "my employer desiring," he says, "after some weeks, to have me in the composing room, i left the pressmen. a new _bien-venu_ for drink, being five shillings, was demanded of me by the compositors. i thought it an imposition, as i had paid one to the pressmen. the master thought so too, and forbade my paying it. i stood out two or three weeks, was accordingly considered as an _excommunicate_, and had so many little pieces of private malice practised on me by mixing my sorts, transposing and breaking my matter, &c. &c., if ever i stepped out of the room, and all ascribed to the _chapel ghost_, which, they said, ever haunted those not regularly admitted, that, notwithstanding my master's protection, i found myself obliged to comply and pay the money." chapter xvi. "let not this weak, unknowing hand, presume thy bolts to throw."--pope. the great fires of the parliament close and the high street were events of this winter. a countryman, who had left town when the old spire of the tron church was blazing like a torch, and the large group of buildings nearly opposite the cross still enveloped in flame from ground-floor to roof-tree, passed our work-shed, a little after two o'clock, and, telling us what he had seen, remarked that, if the conflagration went on as it was doing, we would have, as our next season's employment, the old town of edinburgh to rebuild. and as the evening closed over our labours, we went in to town in a body, to see the fires that promised to do so much for us. the spire had burnt out, and we could but catch between us and the darkened sky, the square abrupt outline of the masonry a-top that had supported the wooden broach, whence, only a few hours before, fergusson's bell had descended in a molten shower. the flames, too, in the upper group of buildings, were restricted to the lower stories, and flared fitfully on the tall forms and bright swords of the dragoons, drawn from the neighbouring barracks, as they rode up and down the middle space, or gleamed athwart the street on groups of wretched-looking women and ruffian men, who seemed scanning with greedy eyes the still unremoved heaps of household goods rescued from the burning tenements. the first figure that caught my eye was a singularly ludicrous one. removed from the burning mass but by the thickness of a wall, there was a barber's shop brilliantly lighted with gas, the uncurtained window of which permitted the spectators outside to see whatever was going on in the interior. the barber was as busily at work as if he were a hundred miles from the scene of danger, though the engines at the time were playing against the outside of his gable wall; and the immediate subject under his hands, as my eye rested upon him, was an immensely fat old fellow, on whose round bald forehead and ruddy cheeks the perspiration, occasioned by the oven-like heat of the place, was standing out in huge drops, and whose vast mouth, widely opened to accommodate the man of the razor, gave to his countenance such an expression as i have sometimes seen in grotesque gothic heads of that age of art in which the ecclesiastical architect began to make sport of his religion. the next object that presented itself was, however, of a more sobering description. a poor working man, laden with his favourite piece of furniture, a glass-fronted press or cupboard, which he had succeeded in rescuing from his burning dwelling, was emerging from one of the lanes, followed by his wife, when, striking his foot against some obstacle in the way, or staggering from the too great weight of his load, he tottered against a projecting corner, and the glazed door was driven in with a crash. there was hopeless misery in the wailing cry of his wife--"oh, ruin, ruin!--_it's_ lost too!" nor was his own despairing response less sad:--"ay, ay, puir lassie, its a' at an end noo." curious as it may seem, the wild excitement of the scene had at first rather exhilarated than depressed my spirits; but the incident of the glass cupboard served to awaken the proper feeling; and as i came more into contact with the misery of the catastrophe, and marked the groups of shivering houseless creatures that watched beside the broken fragments of their stuff, i saw what a dire calamity a great fire really is. nearly two hundred families were already at this time cast homeless into the streets. shortly before quitting the scene of the conflagration for the country, i passed along a common stair, which led from the parliament close towards the cowgate, through a tall old domicile, eleven stories in height, and i afterwards remembered that the passage was occupied by a smouldering oppressive vapour, which, from the direction of the wind, could scarce have been derived from the adjacent conflagration, though at the time, without thinking much of the circumstance, i concluded it might have come creeping westwards on some low cross current along the narrow lanes. in less than an hour after that lofty tenement was wrapt in flames, from the ground story to more than a hundred feet over its tallest chimneys, and about sixty additional families, its tenants, were cast into the streets with the others. my friend william ross afterwards assured me, that never had he witnessed anything equal in grandeur to this last of the conflagrations. directly over the sea of fire below, the low-browed clouds above seemed as if charged with a sea of blood, that lightened and darkened by fits as the flames rose and fell; and far and wide, tower and spire, and tall house-top, glared out against a background of darkness, as if they had been brought to a red heat by some great subterranean, earth-born fire, that was fast rising to wrap the entire city in destruction. the old church of st. giles, he said, with the fantastic masonry of its pale grey tower, bathed in crimson, and that of its dark rude walls suffused in a bronzed umber, and with the red light gleaming inwards through its huge mullioned windows, and flickering on its stone roof, formed one of the most picturesque objects he had ever seen.[ ] i sometimes heard old dr. colquhoun of leith preach. there were fewer authors among the clergy in those days than now; and i felt a special interest in a living divine who had written so good a book, that my uncle sandy--no mean judge in such matters--had assigned to it a place in his little theological library, among the writings of the great divines of other ages. the old man's preaching days, ere the winter of , were well-nigh done: he could scarce make himself heard over half the area of his large, hulking chapel, which was, however, always less than half filled; but, though the feeble tones teasingly strained the ear, i liked to listen to his quaintly attired but usually very solid theology, and found, as i thought, more matter in his discourses than in those of men who spoke louder and in a flashier style. the worthy man, however, did me a mischief at this time. there had been a great musical festival held in edinburgh about three weeks previous to the conflagration, at which oratorios were performed in the ordinary pagan style, in which amateurs play at devotion, without even professing to feel it; and the doctor, in his first sermon after the great fires, gave serious expression to the conviction, that they were judgments sent upon edinburgh, to avenge the profanity of its musical festival. edinburgh had sinned, he said, and edinburgh was now punished; and it was according to the divine economy, he added, that judgments administered exactly after the manner of the infliction which we had just witnessed should fall upon cities and kingdoms. i liked the reasoning very ill. i knew only two ways in which god's judgments could be determined to be really such--either through direct revelation from god himself, or in those cases in which they take place so much in accordance with his fixed laws, and in such relation to the offence or crime visited in them by punishment, that man, simply by the exercise of his rational faculties, and reasoning from cause to effect, as is his nature, can determine them for himself. and the great edinburgh fires had come under neither category. god did not reveal that he had punished the tradesmen and mechanics of the high street for the musical sins of the lawyers and landowners of abercromby place and charlotte square; nor could any natural relation be established between the oratorios in the parliament house or the concerts in the theatre royal, and the conflagrations opposite the cross or at the top of the tron church steeple. all that could be proven in the case were the facts of the festival and of the fires; and the further fact, that, so far as could be ascertained, there was no visible connexion between them, and that it was not the people who had joined in the one that had suffered from the others. and the doctor's argument seemed to be the perilous loose one, that as god had sometimes of old visited cities and nations with judgments which had no apparent connexion with the sins punished, and which could not be recognised as judgments had not he himself told that such they were, the edinburgh fires, of which he had told nothing, might be properly regarded--seeing that they had in the same way no connexion with the oratorios, and had wrought no mischief to the people who had patronized the oratorios--as special judgments on the oratorios. the good old papist had said, "i believe because it is impossible." what the doctor in this instance seemed to say was, "i believe because it is not in the least likely." if, i argued, dr. colquhoun's own house and library had been burnt, he would no doubt very properly have deemed the infliction a great trial to himself; but on what principle could he have further held that it was not only a trial to himself, but also a judgment on his neighbour? if we must not believe that the falling of the tower of siloam was a special visitation on the sins of the poor men whom it crushed, how, or on what grounds, are we to believe that it was a special visitation on the sins of the men whom it did not in the least injure? i fear i remembered dr. colquhoun's remarks on the fire better than aught else i ever heard from him; nay, i must add, that nothing had i ever found in the writings of the sceptics that had a worse effect on my mind; and i now mention the circumstance to show how sober in applications of the kind, in an age like the present, a theologian should be. it was some time ere i forgot the ill savour of that dead fly; and it was to beliefs of a serious and very important class that it served for a time to impart its own doubtful character. but from the minister whose chapel i oftenest attended, i was little in danger of having my beliefs unsettled by reasonings of this stumbling cast. "be sure," said both my uncles, as i was quitting cromarty for the south, "be sure you go and hear dr. m'crie." and so dr. m'crie i did go and hear; and not once or twice, but often. the biographer of knox--to employ the language in which wordsworth describes the humble hero of the "excursion"-- "was a man whom no one could have passed without remark." and on first attending his church, i found that i had unwittingly seen him before, and that without remark i had _not_ passed him. i had extended one of my usual evening walks, shortly after commencing work at niddry, in the direction of the southern suburb of edinburgh, and was sauntering through one of the green lanes of liberton, when i met a gentleman whose appearance at once struck me. he was a singularly erect, spare, tall man, and bore about him an air which, neither wholly clerical nor wholly military, seemed to be a curious compound of both. the countenance was pale, and the expression, as i thought, somewhat melancholy; but an air of sedate power sat so palpably on every feature, that i stood arrested as he passed, and for half a minute or so remained looking after him. he wore, over a suit of black, a brown great-coat, with the neck a good deal whitened by powder, and the rim of the hat behind, which was slightly turned up, bore a similar stain. "there is mark about that old-fashioned man," i said to myself: "who or what can he be?" curiously enough, the apparent combination of the military and the clerical in his gait and air suggested to me sir richard steele's story, in the "tattler," of the old officer who, acting in the double capacity of major and chaplain to his regiment, challenged a young man for blasphemy, and after disarming, would not take him to mercy until he had first begged pardon of god upon his knees on the duelling ground, for the irreverence with which he had treated his name. my curiosity regarding the stranger gentleman was soon gratified. next sabbath i attended the doctor's chapel, and saw the tall, spare, clerico-military looking man in the pulpit. i have a good deal of faith in the military air, when, in the character of a natural trait, i find it strongly marking men who never served in the army. i have not yet seen it borne by a civilian who had not in him at least the elements of the soldier; nor can i doubt that, had dr. m'crie been a scotch covenanter of the times of charles ii, the insurgents at bothwell would have had what they sadly wanted--a general. the shrewd sense of his discourses had great charms for me; and, though not a flashy, nor, in the ordinary sense of the term, even an eloquent preacher, there were none of the other edinburgh clergy his contemporaries to whom i found i could listen with greater profit or satisfaction. a simple incident which occurred during my first morning attendance at his chapel, strongly impressed me with a sense of his sagacity. there was a great deal of coughing in the place, the effect of a recent change of weather; and the doctor, whose voice was not a strong one, and who seemed somewhat annoyed by the ruthless interruptions, stopping suddenly short in the middle of his argument, made a dead pause. when people are taken greatly by surprise, they cease to cough--a circumstance on which he had evidently calculated. every eye was now turned towards him, and for a full minute so dead was the silence, that one might have heard a pin drop. "i see, my friends," said the doctor, resuming speech, with a suppressed smile--"i see you can be all quiet enough when i am quiet." there was not a little genuine strategy in the rebuke; and as cough lies a good deal more under the influence of the will than most coughers suppose, such was its effect, that during the rest of the day there was not a tithe of the previous coughing. the one-roomed cottage which i shared with its three other inmates, did not present all the possible conveniences for study; but it had a little table in a corner, at which i contrived to write a good deal; and my book-shelf already exhibited from twenty to thirty volumes, picked up on saturday evenings at the book-stalls of the city, and which were all accessions to my little library. i, besides, got a few volumes to read from my friend william ross, and a few more through my work-fellow cha; and so my rate of acquirement in book-knowledge, if not equal to that of some former years, at least considerably exceeded what it had been in the previous season, which i had spent in the highlands, and during which i had perused only three volumes--one of the three a slim volume of slim poems, by a lady, and the other, that rather curious than edifying work, "presbyterian eloquence displayed." the cheap literature had not yet been called into existence; and, without in the least undervaluing its advantages, it was, i daresay, better on the whole as a mental exercise, and greatly better in the provision which it made for the future, that i should have to urge my way through the works of our best writers in prose and verse--works which always made an impression on the memory--than that i should have been engaged instead in picking up odds and ends of information from loose essays, the hasty productions of men too little vigorous, or too little at leisure, to impress upon their writings the stamp of their own individuality. in quiet moonlight nights i found it exceedingly pleasant to saunter all alone through the niddry woods. moonlight gives to even leafless groves the charms of full foliage, and conceals tameness of outline in a landscape. i found it singularly agreeable, too, to listen, from a solitude so profound as that which a short walk secured to me, to the distant bells of the city ringing out, as the clock struck eight, the old curfew peal; and to mark, from under the interlacing boughs of a long-arched vista, the intermittent gleam of the inchkeith light now brightening and now fading, as the lanthorn revolved. in short, the winter passed not unpleasantly away: i had now nothing to annoy me in the work-shed; and my only serious care arose from my unlucky house in leith, for which i found myself summoned one morning, by an officer-looking man, to pay nearly three pounds--the last instalment which i owed, i was told, as one of the heritors of the place, for its fine new church. i must confess i was wicked enough to wish on this occasion that the property on the coal-hill had been included in the judgment on the musical festival. but shortly after, not less to my astonishment than delight, i was informed by mr. veitch that he had at length found a purchaser for my house; and, after getting myself served heir to my father before the court of the canongate, and paying a large arrear of feu-duty to that venerable corporation, in which i had to recognise my feudal superior, i got myself as surely dissevered from the coal-hill as paper and parchment could do it, and pocketed, in virtue of the transaction, a balance of about fifty pounds. as nearly as i could calculate on what the property had cost us, from first to last, the _composition_ which it paid was one of about five shillings in the pound. and such was the concluding passage in the history of a legacy which threatened for a time to be the ruin of the family. when i last passed along the coal-hill, i saw my umquhile house existing as a bit of dingy wall, a single storey in height, and perforated by three narrow old-fashioned doors, jealously boarded up, and apparently, as in the days when it was mine, of no manner of use in the world. i trust, however, it is no longer the positive mischief to its proprietor that it was to me. the busy season had now fairly commenced: wages were fast mounting up to the level of the former year, which they ultimately overtopped; and employment had become very abundant. i found, however, that it might be well for me to return home for a few months. the dust of the stone which i had been hewing for the last two years had begun to affect my lungs, as they had been affected in the last autumn of my apprenticeship, but much more severely; and i was too palpably sinking in flesh and strength to render it safe for me to encounter the consequences of another season of hard work as a stone-cutter. from the stage of the malady at which i had already arrived, poor workmen, unable to do what i did, throw themselves loose from their employment, and sink in six or eight months into the grave--some at an earlier, some at a later period of life; but so general is the affection, that few of our edinburgh stone-cutters pass their fortieth year unscathed, and not one out of every fifty of their number ever reaches his forty-fifth year. i accordingly engaged my passage for the north in an inverness sloop, and took leave of my few friends--of the excellent foreman of the niddry squad, and of cha and john wilson, with both of whom, notwithstanding their opposite characters, i had become very intimate. among the rest, too, i took leave of a paternal cousin settled in leith, the wife of a genial-hearted sailor, master of a now wholly obsolete type of vessel, one of the old leith and london smacks, with a huge single mast, massive and tall as that of a frigate, and a mainsail of a quarter of an acre. i had received much kindness from my cousin, who, besides her relationship to my father, had been a contemporary and early friend of my mother's; and my welcome from the master her husband--one of the best-natured men i ever knew--used always to be one of the heartiest. and after parting from cousin marshall, i mustered up resolution enough to call on yet another cousin. cousin william, the eldest son of my sutherlandshire aunt, had been for some years settled in edinburgh, first as an upper clerk and manager--for, after his failure as a merchant he had to begin the world anew; and now, in the speculation year, he had succeeded in establishing a business for himself, which bore about it a hopeful and promising air so long as the over-genial season lasted, but fell, with many a more deeply-rooted establishment, in the tempest which followed. on quitting the north, i had been charged with a letter for him by his father, which i knew, however, to be wholly recommendatory of myself, and so i had failed to deliver it. cousin william, like uncle james, had fully expected that i was to make my way in life in some one of the learned professions; and as his position--though, as the result unfortunately showed, a not very secure one--was considerably in advance of mine, i kept aloof from him, in the character of a poor relation, who was quite as proud as he was poor, and in the belief that his new friends, of whom, i understood, he had now well-nigh as many as before, would hold that the cousinship of a mere working man did him little credit. he had learned from home, however, that i was in edinburgh, and had made not a few ineffectual attempts to find me out, of which i had heard; and now, on forming my resolution to return to the north, i waited upon him at his rooms in ambrose's lodgings--at that time possessed of a sort of classical interest, as the famous blackwood club, with christopher north at its head, used to meet in the hotel immediately below. cousin william had a warm heart, and received me with great kindness, though i had, of course, to submit to the scold which i deserved; and as some young friends were to look in upon him in the evening, he said, i had to do what i would fain have avoided, perform penance, by waiting, on his express invitation, to meet with them. they were, i ascertained, chiefly students of medicine and divinity, in attendance at the classes of the university, and not at all the formidable sort of persons i had feared to meet; and finding nothing very unattainable in their conversation, and as cousin william made a dead set on me "to bring me out," i at length ventured to mingle in it, and found my reading stand me in some stead. there was a meeting, we were told, that evening, in the apartment below, of the blackwood club. the night i spent with my cousin was, if our information was correct, and the _noctes_ not a mere myth, one of the famous _noctes ambrosiance_; and fain would i have seen, for but a moment, from some quiet corner, the men whose names fame had blown so widely; but i have ever been unlucky in the curiosity--though i have always strongly entertained it--which has the personal appearance of celebrated men for its object. i had ere now several times lingered in castle street of a saturday evening, opposite the house of sir walter scott, in the hope of catching a glimpse of that great writer and genial man, but had never been successful i could fain, too, have seen hogg (who at the time occasionally visited edinburgh); with jeffrey; old dugald stewart, who still lived; _delta_, and professor wilson: but i quitted the place without seeing any of them; and ere i again returned to the capital, ten years after, death had been busy in the high places, and the greatest of their number was no longer to be seen. in short, dr. m'crie was the only man whose name promises to live, of whose personal appearance i was able to carry away with me at this time a distinct image. addison makes his _spectator_ remark, rather in joke than earnest, that "a reader seldom peruses a book with pleasure till he knows whether the writer of it be a black or a fair man, of a mild or choleric disposition, married or a bachelor, with other particulars of the like nature, that conduce very much to the right understanding of an author." i am inclined to say nearly as much, without being the least in joke. i think i understand an author all the better for knowing exactly how he looked. i would have to regard the massive vehemence of the style of chalmers as considerably less characteristic of the man, had it been dissociated from the broad chest and mighty structure of bone; and the warlike spirit which breathes, in a subdued but still very palpable form, in the historical writings of the elder m'crie, strikes me as singularly in harmony with the military air of this presbyterian minister of the type of knox and melville. however theologians may settle the meaning of the text, it is one of the grand lessons of his writings, that such of the churches of the reformation as did _not_ "take the sword, perished by the sword." i was accompanied to the vessel by my friend william ross, from whom i, alas! parted for the last time; and, when stepping aboard, cousin william, whom i had scarce expected to see, but who had snatched an hour from business, and walked down all the way to leith to bid me farewell, came forward to grasp me by the hand. i am not much disposed to quarrel with the pride of the working man, when according to johnson and chalmers, it is a defensive, not an aggressive pride; but it does at times lead him to be somewhat less than just to the better feelings of the men who occupy places in the scale a little higher than his own. cousin william, from whom i had kept so jealously aloof, had a heart of the finest water. his after course was rough and unprosperous. after the general crash of - , he struggled on in london for some six or eight years, in circumstances of great difficulty; and then, receiving some surbodinate appointment in connexion with the stipendiary magistracy of the west indies, he sailed for jamaica--where, considerably turned of fifty at the time--he soon fell a victim to the climate. in my voyage north, i spent about half as many days on sea, between leith roads and the sutors of cromarty, as the cunard steamers now spend in crossing the atlantic. i had taken a cabin passage, not caring to subject my weakened lungs to the exposure of a steerage one; but during the seven days of thick, foggy mornings, clear moonlight nights, and almost unbroken calms, both night and morning, in which we tided our slow way north, i was much in the forecastle with the men, seeing how sailors lived, and ascertaining what they were thinking about, and how. we had rare narratives at nights-- "wonderful stories of battle and wreck, that were told by the men of the watch." some of the crew had been voyagers in their time to distant parts of the world; and though no existence can be more monotonous than the every-day life of the seaman, the profession has always its bits of striking incident, that, when strung together, impart to it an air of interest which its ordinary details sadly want, and which lures but to disappoint the young lads of a romantic cast, who are led to make choice of it in its presumed character as a continued series of stirring events and exciting adventures. what, however, struck me as curious in the narratives of my companions, was the large mixture of the supernatural which they almost always exhibited. the story of jack grant the mate, given in an early chapter, may be regarded as not inadequately representative of the sailor stories which were told on deck and forecastle, along at least the northern coasts of scotland, nearly thirty years later. that life of peril which casts the seaman much at the mercy of every rough gale and lee-shore, and in which his calculations regarding ultimate results must be always very doubtful, has a strong tendency to render him superstitious. he is more removed, too, than the landsman of his education and standing, from the influence of general opinion, and the mayhap over-sceptical teaching of the press; and, as a consequence of their position and circumstances, i found, at this period, seamen of the generation to which i myself belonged as firm believers in wraiths, ghosts, and death-warnings, as the landward contemporaries of my grandfather had been sixty years before. a series of well-written nautical tales had appeared shortly previous to this time in one of the metropolitan monthlies--the _london magazine_, if i rightly remember; and i was now interested to find in one of the sailors' stories, the original of decidedly the best of their number--"the doomed man." the author of the series--a mr. hamilton, it was said, who afterwards became an irvingite teacher, and grew too scrupulous to exercise in fiction a very pleasing pen, though he continued to employ, as a portrait-painter, a rather indifferent pencil--had evidently sought such opportunities of listening to sailor's stories as those on which i had at this time thrust myself. very curious materials for fiction may be found in this way by the _littérateur_. it must be held that sir walter scott was no incompetent judge of the capabilities, for the purposes of the novelist, of a piece of narrative; and yet we find him saying of the story told by a common sailor to his friend william clerk, which he records in the "letters on demonology and witchcraft," that "the tale, properly managed, might have made the fortune of a romancer." at times by day--for the sailors' stories were stories of the night--i found interesting companionship in the society of a young student of divinity, one of the passengers, who, though a lad of parts and acquirements, did not deem it beneath him to converse on literary subjects with a working man in pale moleskin, and with whom i did not again meet until many years after, when we were both actively engaged in prosecuting the same quarrel--he as one of the majority of the presbytery of auchterarder, and i as editor of the leading newspaper of the non-intrusion party. perhaps the respected free church minister of north leith may be still able to call to memory--not, of course, the subjects, but the _fact_, of our discussions on literature and the belles-lettres at this time; and that, on asking me one morning whether i had not been, according to burns, "crooning to mysel'," when on deck during the previous evening, what seemed from the cadence to be verse, i ventured to submit to him, as my night's work, a few descriptive stanzas. and, as forming in some sort a memorial of our voyage, and in order that my friendly critic may be enabled, after the lapse of considerably more than a quarter of a century, to review his judgment respecting them, i now submit them to the reader:-- stanzas written at sea. joy of the poet's soul, i court thy aid; * * * * * around our vessel heaves the midnight wave; the cheerless moon sinks in the western sky; reigns breezeless silence!--in her ocean cave the mermaid rests, while her fond lover nigh, marks the pale star-beams as they fall from high. gilding with tremulous light her couch of sleep. why smile incred'lous? the rapt muse's eye through earth's dark caves, o'er heaven's fair plains, can sweep, can range its hidden cell, where toils the unfathom'd deep. on ocean's craggy floor, beneath the shade of bushy rock-weed tangled, dusk, and brown, she sees the wreck of founder'd vessel laid, in slimy silence, many a fathom down from where the star-beam trembles; o'er it thrown are heap'd the treasures men have died to gain. and in sad mockery of the parting groan, that bubbled 'mid the wild unpitying main, quick gushing o'er the bones, the restless tides complain. gloomy and wide rolls the sepulchral sea, grave of my kindred, of my sire the grave! perchance, where now he sleeps, a space for me is mark'd by fate beneath the deep green wave. it well may he! poor bosom, why dost heave thus wild? oh, many a care, troublous and dark. on earth attends thee still; the mermaid's cave grief haunts not; sure 'twere pleasant there to mark, serene, at noontide hour, the sailor's passing barque. sure it were pleasant through the vasty deep, when on its bosom plays the golden beam. with headlong speed by bower and cave to sweep; when flame the waters round with emerald gleam-- when, borne from high by tides and gales, the scream of sea-mew softened falls--when bright and gay the crimson weeds, proud ocean's pendants, stream from trophied wrecks and rock-towers darkly grey-- through scenes so strangely fair 'twere pleasant, sure, to stray. why this strange thought? if, in that ocean laid. the ear would cease to hear, the eye to see, though sights and sounds like these circled my bed, wakeless and heavy would my slumbers be: though the mild soften'd sun-light beam'd on me (if a dull heap of bones retained my name, that bleach'd or blacken'd 'mid the wasteful sea), its radiance all unseen, its golden beam in vain through coral groves or emerald roofs might stream. yet dwells a spirit in this earthy frame which oceans cannot quench nor time destroy;-- a deathless, fadeless ray, a heavenly flame, that pure shall rise when fails each base alloy that earth instils, dark grief, or baseless joy: then shall the ocean's secrets meet its sight;-- for i do hold that happy souls enjoy a vast all-reaching range of angel-flight, from the fair source of day, even to the gates of night. now night's dark veil is rent; on yonder land, that blue and distant rises o'er the main, i see the purple sky of morn expand, scattering the gloom. then cease my feeble strain: when darkness reign'd, thy whisperings soothed my pain-- the pain by weariness and languor bred. but now my eyes shall greet a lovelier scene than fancy pictured: from his dark green bed soon shall the orb of day exalt his glorious head. i found my two uncles, cousin george, and several other friends and relations, waiting for me on the cromarty beach; and was soon as happy among them as a man suffering a good deal from debility, but not much from positive pain, could well be. when again, about ten years after this time, i visited the south of scotland, it was to receive the instructions necessary to qualify me for a bank accountant; and when i revisited it at a still later period, it was to undertake the management of a metropolitan newspaper. in both these instances i mingled with a different sort of persons from those with whom i had come in contact in the years - . and, in now taking leave of the lower class, i may be permitted to make a few general remarks regarding them. it is a curious change which has taken place in this country during the last hundred years. up till the times of the rebellion of , and a little later, it was its remoter provinces that formed its dangerous portions; and the effective strongholds from which its advance-guards of civilisation and good order gradually gained upon old anarchy and barbarism, were its great towns. we are told by ecclesiastical historians, that in rome, after the age of constantine, the term villager (_pagus_) came to be regarded as synonymous with heathen, from the circumstance that the worshippers of the gods were then chiefly to be found in remote country places; and we know that in scotland the reformation pursued a course exactly resembling that of christianity itself in the old roman world: it began in the larger and more influential towns; and it was in the remoter country districts that the displaced religion lingered longest, and found its most efficient champions and allies. edinburgh, glasgow, perth, st. andrews, dundee, were all protestant, and sent out their well-taught burghers to serve in the army of the lords of the congregation, when huntly and hamilton were arming their vassals to contend for the obsolete faith. in a later age the accessible lowlands were imbued with an evangelistic presbyterianism, when the more mountainous and inaccessible provinces of the country were still in a condition to furnish, in what was known as the highland host, a dire instrument of persecution. even as late as the middle of the last century, "sabbath," according to a popular writer, "never got aboon the pass of killicrankie;" and the stuarts, exiled for their adherence to popery, continued to found almost their sole hopes of restoration on the swords of their co-religionists the highlanders. during the last hundred years, however, this old condition of matters has been strangely reversed; and it is in the great towns that _paganism_ now chiefly prevails. in at least their lapsed classes--a rapidly increasing proportion of their population--it is those cities of our country which first caught the light of religion and learning, that have become preeminently its dark parts; just, if i may employ the comparison, as it is those portions of the moon which earliest receive the light when she is in her increscent state, and shine like a thread of silver in the deep blue of the heavens, that first become dark when she falls into the wane. it is mainly during the elapsed half of the present century that this change for the worse has taken place in the large towns of scotland. in the year it was greatly less than half accomplished; but it was fast going on; and i saw, partially at least, the processes in operation through which it has been effected. the cities of the country have increased their population during the past fifty years greatly beyond the proportion of its rural districts--a result in part of the revolutions which have taken place in the agricultural system of the lowlands, and of the clearances of the highlands; and in part also of that extraordinary development of the manufactures and trade of the kingdom which the last two generations have witnessed. of the wilder edinburgh mechanics with whom i formed at this time any acquaintance, less than one-fourth were natives of the place. the others were mere settlers in it, who had removed mostly from country districts and small towns, in which they had been known, each by his own circle of neighbourhood, and had lived, in consequence, under the wholesome influence of public opinion. in edinburgh--grown too large at the time to permit men to know aught of their neighbours--they were set free from this wholesome influence, and, unless when under the guidance of higher principle, found themselves at liberty to do very much as they pleased. and--with no _general_ opinion to control--cliques and parties of their wilder spirits soon formed in their sheds and workshops a standard of opinion of their own, and found only too effectual means of compelling their weaker comrades to conform to it. and hence a great deal of wild dissipation and profligacy, united, of course, to the inevitable improvidence. and though dissipation and improvidence are quite compatible with intelligence in the first generation, they are sure always to part company from it in the second. the family of the unsteady spendthrift workman is never a well-taught family. it is reared up in ignorance; and, with evil example set before and around it, it almost necessarily takes its place among the lapsed classes. in the third generation the descent is of course still greater and more hopeless than in the second. there is a type of even physical degradation already manifesting itself in some of our large towns, especially among degraded females, which is scarce less marked than that exhibited by the negro, and which both my edinburgh and glasgow readers must have often remarked on the respective high streets of these cities. the features are generally bloated and overcharged, the profile lines usually concave, the complexion coarse and high, and the expression that of a dissipation and sensuality become chronic and inherent. and how this class--constitutionally degraded, and with the moral sense, in most instances, utterly undeveloped and blind--are ever to be reclaimed, it is difficult to see. the immigrant irish form also a very appreciable element in the degradation of our large towns. they are, however, _pagans_, not of the new, but of the old type: and are chiefly formidable from the squalid wretchedness of a physical character which they have transferred from their mud cabins into our streets and lanes, and from the course of ruinous competition into which they have entered with the unskilled labourers of the country, and which has had the effect of reducing our lowlier countrymen to a humbler level than they perhaps ever occupied before. meanwhile, this course of degradation is going on, in all our larger towns, in an ever-increasing ratio; and all that philanthropy and the churches are doing to counteract it is but as the discharge of a few squirts on a conflagration. it is, i fear, preparing terrible convulsions for the future. when the dangerous classes of a country were located in its remote districts, as in scotland in the early half of the last century, it was comparatively easy to deal with them: but the _sans culottes_ of paris in its first revolution, placed side by side with its executive government, proved very formidable indeed; nor is it, alas! very improbable that the ever-growing masses of our large towns, broken loose from the sanction of religion and morals, may yet terribly avenge on the upper classes and the churches of the country the indifferency with which they have been suffered to sink. i was informed by cousin george, shortly after my arrival, that my old friend of the doocot cave, after keeping shop as a grocer for two years, had given up business, and gone to college to prepare himself for the church. he had just returned home, added george, after completing his first session, and had expressed a strong desire to meet with me. his mother, too, had joined in the invitation--would i not take tea with them that evening?--and cousin george had been asked to accompany me. i demurred; but at length set out with george, and, after an interruption in our intercourse of about five years, spent the evening with my old friend. and for years after we were inseparable companions, who, when living in the same neighbourhood, spent together almost every hour not given to private study or inevitable occupation, and who, when separated by distance, exchanged letters enough to fill volumes. we had parted boys, and had now grown men; and for the first few weeks we took stock of each other's acquirements and experiences, and the measure of each other's calibre, with some little curiosity. the mind of my friend had developed rather in a scientific than literary direction. he afterwards carried away the first mathematical prize of his year at college, and the second in natural philosophy; and he had, i now found, great acuteness as a metaphysician, and no inconsiderable acquaintance with the antagonistic positions of the schools of hume and reid. on the other hand, my opportunities of observation had been perhaps greater than his, and my acquaintance with men, and even with books, more extensive; and in the interchange of idea which we carried on, both were gainers: he occasionally picked up in our conversations a fact of which he had been previously ignorant; and i, mayhap, learned to look more closely than before at an argument. i introduced him to the eathie lias, and assisted him in forming a small collection, which, ere he ultimately dissipated it, contained some curious fossils--among the others, the second specimen of _pterichthys_ ever found; and he, in turn, was able to give me a few geological notions, which, though quite crude enough--for natural science was not taught at the university which he attended--i found of use in the arrangement of my facts--now become considerable enough to stand in need of those threads of theory without which large accumulations of fact refuse to hang together in the memory. there was one special hypothesis which he had heard broached, and the utter improbability of which i was not yet geologist enough to detect, which for a time filled my whole imagination. it had been said, he told me, that the ancient world, in which my fossils, animal and vegetable, had flourished and decayed--a world greatly older than that before the flood--had been tenanted by rational, responsible beings, for whom, as for the race to which we ourselves belong, a resurrection and a day of final judgment had awaited. but many thousands of years had elapsed since that day--emphatically the _last_ to the pre-adamite race--had come and gone. of all the accountable creatures that had been summoned to its bar, bone had been gathered to its bone, so that not a vestige of the framework of their bodies occurred in the rocks or soils in which they had been originally inhumed; and, in consequence, only the remains of their irresponsible contemporaries, the inferior animals, and of the vegetable productions of their fields and forests, were now to be found. the dream filled for a time my whole imagination; but though poetry might find ample footing on a hypothesis so suggestive and bold, i need scarce say that it has itself no foundation in science. man had _no_ responsible predecessor on earth. at the determined time, when his appointed habitation was completely fitted for him, he came and took possession of it; but the old geologic ages had been ages of immaturity--_days_ whose work as a work of promise was "good," but not yet "very good," nor yet ripened for the appearance of a moral agent, whose nature it is to be a fellow-worker with the creator in relation to even the physical and the material. the planet which we inhabit seems to have been prepared for man, and for man only. partly through my friend, but in part also from the circumstance that i retained a measure of intimacy with such of my schoolfellows as had subsequently prosecuted their education at college, i was acquainted, during the later years in which i wrought as a mason, with a good many university-taught lads; and i sometimes could not avoid comparing them in my mind with working men of, as nearly as i could guess, the same original calibre. i did not always find that general superiority on the side of the scholar which the scholar himself usually took for granted. what he had specially studied he knew, save in rare and exceptional cases, better than the working man; but while the student had been mastering his greek and latin, and expatiating in natural philosophy and the mathematics, the working man, if of an inquiring mind, had been doing something else; and it is at least a fact, that all the great readers of my acquaintance at this time--the men most extensively acquainted with english literature--were not the men who had received the classical education. on the other hand, in framing an argument, the advantage lay with the scholars. in that common sense, however, which reasons but does not argue, and which enables men to pick their stepping prudently through the journey of life, i found that the classical education gave no superiority whatever; nor did it appear to form so fitting an introduction to the realities of business as that course of dealing with things tangible and actual in which the working man has to exercise his faculties, and from which he derives his experience. one cause of the over-low estimate which the classical scholar so often forms of the intelligence of that class of the people to which our skilled mechanics belong, arises very much from the forwardness of a set of blockheads who are always sure to obtrude themselves upon his notice, and who come to be regarded by him as average specimens of their order. i never yet knew a truly intelligent mechanic obtrusive. men of the stamp of my two uncles, and of my friend william ross, never press themselves on the notice of the classes above them. a minister newly settled in a charge, for instance, often finds that it is the dolts of his flock that first force themselves upon his acquaintance. i have heard the late mr. stewart of cromarty remark, that the humbler dunderheads of the parish had all introduced themselves to his acquaintance long ere he found out its clever fellows. and hence often sad mistakes on the part of a clergyman in dealing with the people. it seems never to strike him that there may be among them men of his own calibre, and, in certain practical departments, even better taught than he; and that this superior class is always sure to lead the others. and in preaching down to the level of the men of humbler capacity, he fails often to preach to men of any capacity at all, and is of no use. some of the clerical contemporaries of mr. stewart used to allege that, in exercising his admirable faculties in the theological field, he sometimes forgot to lower himself to his people, and so preached over their heads. and at times, when they themselves came to occupy his pulpit, as occasionally happened, they addressed to the congregation sermons quite simple enough for even children to comprehend. i taught at the time a class of boys in the cromarty sabbath-school, and invariably found on these occasions, that while the memories of my pupils were charged to the full with the striking thoughts and graphic illustrations of the very elaborate discourses deemed too high for them, they remembered of the very simple ones, specially lowered to suit narrow capacities, not a single word or note. all the attempts at originating a cheap literature that have failed, have been attempts pitched too low: the higher-toned efforts have usually succeeded. if the writer of these chapters has been in any degree successful in addressing himself as a journalist to the presbyterian people of scotland, it has always been, not by writing _down_ to them, but by doing his best on all occasions to write _up_ to them. he has ever thought of them as represented by his friend william, his uncles, and his cousin george--by shrewd old john fraser, and his reckless though very intelligent acquaintance cha; and by addressing to them on every occasion as good sense and as solid information as he could possibly muster, he has at times succeeded in catching their ear, and perhaps, in some degree, in influencing their judgment. footnote: [ ] the extreme picturesqueness of these fires--in part a consequence of the great height and peculiar architecture of the buildings which they destroyed--caught the nice eye of sir walter scott. "i can conceive," we find him saying, in one of his letters of the period, "no sight more grand or terrible than to see these lofty buildings on fire from top to bottom, vomiting out flames, like a volcano, from every aperture, and finally crashing down one after another, into an abyss of fire, which resembled nothing but hell; for there were vaults of wine and spirits which set up huge jets of flames whenever they were called into activity by the fall of these massive fragments. between the corner of the parliament square and the tron church, all is destroyed excepting some new buildings at the lower extremity." chapter xvii. "beware, lorenzo, a slow, sudden death."--young. there was one special subject which my friend, in our quiet evening walks, used to urge seriously upon my attention. he had thrown up, under strong religious impressions, what promised to be so good a business, that in two years he had already saved money enough to meet the expenses of a college course of education. and assuredly, never did man determine on entering the ministry with views more thoroughly disinterested than his. patronage ruled supreme in the scottish establishment at the time; and my friend had no influence and no patron; but he could not see his way clear to join with the evangelical dissenters or the secession; and believing that the most important work on earth is the work of saving souls, he had entered on his new course in the full conviction that, if god had work for him of this high character to do, he would find him an opportunity of doing it. and now, thoroughly in earnest, and as part of the special employment to which he had devoted himself, he set himself to press upon my attention the importance, in their personal bearing, of religious concerns. i was not unacquainted with the standard theology of the scottish church. in the parish school i had, indeed, acquired no ideas on the subject; and though i now hear a good deal said, chiefly with a controversial bearing, about the excellent religious influence of our parochial seminaries, i never knew any one who owed other than the merest smattering of theological knowledge to these institutions, and not a single individual who had ever derived from them any tincture, even the slightest, of religious feeling. in truth, during almost the whole of the last century, and for at least the first forty years of the present, the people of scotland were, with all their faults, considerably more christian than the larger part of their schoolmasters. so far as i can remember, i carried in my memory from school only a single remark at all theological in its character, and it was of a kind suited rather to do harm than good. in reading in the class one saturday morning a portion of the hundred and nineteenth psalm, i was told by the master that that ethical poem was a sort of alphabetical acrostic--a circumstance, he added, that accounted for its broken and inconsecutive character as a composition. chiefly, however, from the sabbath-day catechizings to which i had been subjected during boyhood by my uncles, and latterly from the old divines, my uncle sandy's favourites, and from the teachings of the pulpit, i had acquired a considerable amount of religious knowledge. i had thought, too, a good deal about some of the peculiar doctrines of calvinism, in their character as abstruse positions--such as the doctrine of the divine decrees, and of man's inability to assume the initiative in the work of his own conversion. i had, besides, a great admiration of the bible, especially of its narrative and poetical parts; and could scarce give strong enough expression to the contempt which i entertained for the vulgar and tasteless sceptics who, with paine at their head, could speak of it as a weak or foolish book. further, reared in a family circle, some of whose members were habitually devout, and all of whom respected and stood up for religion, and were imbued with the stirring ecclesiastical traditions of their country, i felt that the religious side in any quarrel had a sort of hereditary claim upon me. i believe i may venture to say, that previous to this time i had never seen a religious man badgered for his religion, and much in a minority, without openly taking part with him; nor is it impossible that, in a time of trouble, i might have almost deserved the character given by old john howie to a rather notable "gentleman sometimes called burly," who, "although he was by some reckoned none of the most religious," joined himself to the suffering party, and was "always zealous and honest-hearted." and yet my religion was a strangely incongruous thing. it took the form, in my mind, of a mass of indigested theology, with here and there a prominent point developed out of due proportion, from the circumstance that i had thought upon it for myself; and while entangled, if i may so speak, amid the recesses and under cover of the general chaotic mass, there harboured no inconsiderable amount of superstition, there rested over it the clouds of a dreary scepticism. i have sometimes, in looking back on the doubts and questionings of this period, thought, and perhaps even spoken of myself as an infidel. but an infidel i assuredly was not: my belief was at least as real as my incredulity, and had, i am inclined to think, a much deeper seat in my mind. but wavering between the two extremes--now a believer, and anon a sceptic--the belief usually exhibiting itself as a strongly-based instinct,--the scepticism as the result of some intellectual process--i lived on for years in a sort of uneasy see-saw condition, without any middle ground between the two extremes, on which i could at once reason and believe. that middle ground i now succeeded in finding. it is at once delicate and dangerous to speak of one's own spiritual condition, or of the emotional sentiments on which one's conclusions regarding it are often so doubtfully founded. egotism in the religious form is perhaps more tolerated than in any other; but it is not on that account less perilous to the egotist himself. there need be, however, less delicacy in speaking of one's beliefs than of one's feelings; and i trust i need not hesitate to say, that i was led to see at this time, through the instrumentality of my friend, that my theologic system had previously wanted a central object, to which the heart, as certainly as the intellect, could attach itself; and that the true centre of an efficient _christianity_ is, as the name ought of itself to indicate, "the word made flesh." around this central sun of the christian system--appreciated, however, not as a _doctrine_ which is a mere abstraction, but as a divine person--so truly man, that the affections of the human heart can lay hold upon him, and so truly god, that the mind, through faith, can at all times and in all places be brought into direct contact with him--all that is really religious takes its place in a subsidiary and subordinate relation. i say subsidiary and subordinate. the divine man is the great attractive centre, the sole gravitating point of a system which owes to him all its coherency, and which would be but a chaos were he away. it seems to be the existence of the human nature in this central and paramount object that imparts to christianity, in its subjective character, its peculiar power of influencing and controlling the human mind. there may be men who, through a peculiar idiosyncrasy of constitution, are capable of loving, after a sort, a mere abstract god, unseen and inconceivable; though, as shown by the air of sickly sentimentality borne by almost all that has been said and written on the subject, the feeling in its true form must be a very rare and exceptional one. in all my experience of men, i never knew a genuine instance of it the love of an abstract god seems to be as little natural to the ordinary human constitution as the love of an abstract sun or planet. and so it will be found, that in all the religions that have taken strong hold of the mind of man, the element of a vigorous humanity has mingled, in the character of its gods, with the theistic element. the gods of classic mythology were simply powerful men set loose from the tyranny of the physical laws; and, in their purely human character, as warm friends and deadly enemies, they were both feared and loved. and so the belief which bowed at their shrines ruled the old civilized world for many centuries. in the great ancient mythologies of the east--buddhism and brahmanism--both very influential forms of belief--we have the same elements, genuine humanity added to god-like power. in the faith of the moslem, the human character of the man mahommed, elevated to an all-potential viceregency in things sacred, gives great strength to what without it would be but a weak theism. literally it is allah's supreme prophet that maintains for allah himself a place in the mahommedan mind. again, in popery we find an excess of humanity scarce leas great than in the classical mythology itself, and with nearly corresponding results. though the virgin mother takes, as queen of heaven, a first place in the scheme, and forms in that character a greatly more interesting goddess than any of the old ones who counselled ulysses, or responded to the love of anchises or of endymion, she has to share her empire with the minor saints, and to recognise in them a host of rivals. but undoubtedly to this popular element popery owes not a little of its indomitable strength. in, however, all these forms of religion, whether inherently false from the beginning, or so overlaid in some after stage by the fictitious and the untrue as to have their original substratum of truth covered up by error and fable, there is such a want of coherency between the theistic and human elements, that we always find them undergoing a process of separation. we see the human element ever laying hold on the popular mind, and there manifesting itself in the form of a vigorous superstition; and the theistic element, on the other hand, recognised by the cultivated intellect as the exclusive and only element, and elaborated into a sort of natural theology, usually rational enough in its propositions, but for any practical purpose always feeble and inefficient. such a separation of the two elements took place of old in the ages of the classical mythology; and hence the very opposite characters of the wild but genial and popular fables so exquisitely adorned by the poets, and the rational but uninfluential doctrines received by a select few from the philosophers. such a separation took place, too, in france in the latter half of the last century; and still on the european continent generally do we find this separation represented by the assertors of a weak theism on the one hand, and of a superstitious saint-worship on the other. in the false or corrupted religions, the two indispensable elements of divinity and humanity appear as if blended together by a mere mechanical process; and it is their natural tendency to separate, through a sort of subsidence on the part of the human element from the theistic one, as if from some lack of the necessary affinities. in christianity, on the other hand, when existing in its integrity as the religion of the new testament, the union of the two elements is complete: it partakes of the nature, not of a mechanical, but of a chemical mixture; and its great central doctrine--the true humanity and true divinity of the adorable saviour--is a truth equally receivable by at once the humblest and the loftiest intellects. poor dying children possessed of but a few simple ideas, and men of the most robust intellects, such as the chalmerses, fosters, and halls of the christian church, find themselves equally able to rest their salvation on the _man_ "christ, who is over all, _god_ blessed for ever." of this fundamental truth of the two natures, that condensed enunciation of the gospel which forms the watchword of our faith, "believe in the lord jesus christ, and thou shalt be saved," is a direct and palpable embodiment; and christianity is but a mere name without it. i was impressed at this time by another very remarkable feature in the religion of christ in its subjective character. kames, in his "art of thinking," illustrates, by a curious story, one of his observations on the "nature of man." "nothing is more common," he says, "than love converted into hatred; and we have seen instances of hatred converted into love." and in exemplifying the remark, he relates his anecdote of "unnion and valentine." two english soldiers, who fought in the wars of queen anne--the one a petty officer, the other a private sentinel--had been friends and comrades for years; but, quarrelling in some love affair, they became bitter enemies. the officer made an ungenerous use of his authority, and so annoyed and persecuted the sentinel as almost to fret him into madness; and he was frequently heard to say that he would die to be avenged of him. whole months were spent in the infliction of injuries on the one side, and in the venting of complaints on the other; when, in the midst of their mutual rage, they were both selected, as men of tried courage, to share in some desperate attack, which was, however, unsuccessful; and the officer, in the retreat, was disabled, and struck down by a shot in the thigh. "oh, valentine! and will you leave me here to perish?" he exclaimed, as his old comrade rushed past him. the poor injured man immediately returned; and, in the midst of a thick fire, bore off his wounded enemy to what seemed a place of safety, when he was struck by a chance ball, and fell dead under his burden. the officer, immediately forgetting his wound, rose up, tearing his hair; and, throwing himself on the bleeding body, he cried, "ah, valentine! and was it for me, who have so barbarously used thee, that thou hast died? i will not live after thee." he was not by any means to be forced from the corpse; but was removed with it bleeding in his arms, and attended with tears by all his comrades, who knew of his harshness to the deceased. when brought to a tent, his wounds were dressed by force; but the next day, still calling on valentine, and lamenting his cruelties to him, he died in the pangs of remorse and despair. this surely is a striking story; but the commonplace remark based upon it by the philosopher is greatly less so. men who have loved _do_ often learn to hate the object of their affections; and men who have hated sometimes learn to love: but the portion of the anecdote specially worthy of remark appears to be that which, dwelling on the o'ermastering remorse and sorrow of the rescued soldier, shows how effectually his poor dead comrade had, by dying for him "while he was yet his enemy," "heaped coals of fire upon his head." and such seems to be one of the leading principles on which, with a divine adaptation to the heart of man, the scheme of redemption has been framed. the saviour approved his love, "in that while we were yet sinners, he died for us." there is an inexpressibly great power in this principle; and many a deeply-stirred heart has felt it to its core. the theologians have perhaps too frequently dwelt on the saviour's vicarious satisfaction for human sin in its relation to the offended justice of the father. how, or on what principle, the father was satisfied, i know not, and may never know. the enunciation regarding vicarious satisfaction may be properly received in faith as a _fact_, but, i suspect, not properly reasoned upon until we shall be able to bring the moral sense of deity, with its requirements, within the limits of a small and trivial logic. but the thorough adaptation of the scheme to man's nature is greatly more appreciable, and lies fully within the reach of observation and experience. and how thorough that adaptation is, all who have really looked at the matter ought to be competent to say. does an earthly priesthood, vested with alleged powers to interpose between god and man, always originate an ecclesiastical tyranny, which has the effect, in the end, of shutting up the mass of men from their maker?--here is there a high priest passed into the heavens--the only priest whom the evangelistic protestant recognises as really such--to whom, in his character of mediator between god and man, all may apply, and before whom there need be felt none of that abject prostration of the spirit and understanding which man always experiences when he bends before the merely human priest. is self-righteousness the besetting infirmity of the religious man?--in the scheme of vicarious righteousness it finds no footing. the self-approving pharisee must be content to renounce his own merits, ere he can have part or lot in the fund of merit which alone avails; and yet without personal righteousness he can have no evidence whatever that he has an interest in the all-prevailing imputed righteousness. but it is in the closing scene of life, when man's boasted virtues become so intangible in his estimation that they elude his grasp, and sins and shortcomings, little noted before, start up around him like spectres, that the scheme of redemption appears worthy of the infinite wisdom and goodness of god, and when what the saviour did and suffered seems of efficacy enough to blot out the guilt of every offence. it is when the minor lights of comfort are extinguished that the sun of righteousness shines forth, and more than compensates for them all. the opinions which i formed at this time on this matter of prime importance i found no after occasion to alter or modify. on the contrary, in passing from the subjective to the objective view, i have seen the doctrine of the union of the two natures greatly confirmed. the truths of geology appear destined to exercise in the future no inconsiderable influence on natural theology; and with this especial doctrine they seem very much in accordance. of that long and stately march of creation with which the records of the stony science bring us acquainted, the distinguishing characteristic is progress. there appears to have been a time when there existed on our planet only dead matter unconnected with vitality; and then a time in which plants and animals of a low order began to be, but in which even fishes, the humblest of the vertebrata, were so rare and exceptionable, that they occupied a scarce appreciable place in nature. then came an age of fishes huge of size, and that to the peculiar ichthyic organization added certain well-marked characteristics of the reptilian class immediately above them. and then, after a time, during which the reptile had occupied a place as inconspicuous as that occupied by the fish in the earlier periods of animal life, an age of reptiles of vast bulk and high standing was ushered in. and when, in the lapse of untold ages, _it_ also had passed away, there succeeded an age of great mammals. molluscs, fishes, reptiles, mammals, had each in succession their periods of vast extent; and then there came a period that differed even more, in the character of its master-existence, from any of these creations, than they, with their many vitalities, had differed from the previous inorganic period in which life had not yet begun to be. the human period began--the period of a fellow-worker with god, created in god's own image. the animal existences of the previous ages formed, if i may so express myself, mere figures in the landscapes of the great garden which they inhabited. man, on the other hand, was placed in it to "keep and to dress it;" and such has been the effect of his labours, that they have altered and improved the face of whole continents. our globe, even as it might be seen from the moon, testifies, over its surface, to that unique nature of man, unshared in by any of the inferior animals, which renders him, in things physical and natural, a fellow-worker with the creator who first produced it. and of the identity of at least his intellect with that of his maker, and, of consequence, of the integrity of the revelation which declares that he was created in god's own image, we have direct evidence in his ability of not only conceiving of god's contrivances, but even of reproducing them; and this, not as a mere imitator, but as an original thinker. he may occasionally borrow the principles of his contrivances from the works of the original designer, but much more frequently, in studying the works of the original designer does he discover in them the principles of his own contrivances. he has not been an imitator: he has merely been exercising, with resembling results, the resembling mind, _i.e._, the mind made in the divine image. but the existing scene of things is not destined to be the last. high as it is, it is too low and too imperfect to be regarded as god's finished work: it is merely one of the _progressive_ dynasties; and revelation and the implanted instincts of our nature alike teach us to anticipate a glorious _terminal_ dynasty. in the first dawn of being, simple vitality was united to matter: the vitality thus united became, in each succeeding period, of a higher and yet higher order;--it was in succession the vitality of the mollusc, of the fish, of the reptile, of the sagacious mammal, and, finally, of responsible, immortal man, created in the image of god. what is to be the next advance? is there to be merely a repetition of the past--an introduction a second time of "man made in the image of god?" no! the geologist, in the tables of stone which form his records, finds no example of dynasties once passed away again returning. there has been no repetition of the dynasty of the fish--of the reptile--of the mammal. the dynasty of the future is to have glorified man for its inhabitant; but it is to be the dynasty--the "_kingdom_"--not of glorified man made in the image of god, but of god himself in the form of man. in the doctrine of the two natures, and in the further doctrine that the terminal dynasty is to be peculiarly the dynasty of him in whom the natures are united, we find that required progression beyond which progress cannot go. creation and the creator meet at one point, and in one person. the long ascending line from dead matter to man has been, a progress godwards--not an asymptotical progress, but destined from the beginning to furnish a point of union; and, occupying that point as true god and true man, as creator and created, we recognise the adorable monarch of all the future. it is, as urged by the apostle, the especial glory of our race, that it should have furnished that point of contact at which godhead has united himself, not to man only, but also, through man, to his own universe--to the universe of matter and of mind. i remained for several months in delicate and somewhat precarious health. my lungs had received more serious injury than i had at first supposed; and it seemed at one time rather doubtful whether the severe mechanical irritation which had so fretted them that the air-passages seemed overcharged with matter and stone-dust, might not pass into the complaint which it stimulated, and become confirmed consumption. curiously enough, my comrades had told me in sober earnest--among the rest, cha, a man of sense and observation--that i would pay the forfeit of my sobriety by being sooner affected than they by the stone-cutter's malady: "a good _bouse_" gave, they said, a wholesome fillip to the constitution, and "cleared the sulphur off the lungs;" and mine would suffer for want of the medicine which kept theirs clean. i know not whether there was virtue in their remedy: it seems just possible that the shock given to the constitution by an overdose of strong drink may in certain cases be medicinal in its effects; but they were certainly not in error in their prediction. among the hewers of the party i was the first affected by the malady. i still remember the rather pensive than sad feeling with which i used to contemplate, at this time, an early death, and the intense love of nature that drew me, day after day, to the beautiful scenery which surrounds my native town, and which i loved all the more from the consciousness that my eyes might so soon close upon it for ever. "it _is_ a pleasant thing to behold the sun." among my manuscripts--useless scraps of paper, to which, however, in their character as fossils of the past epochs of my life, i cannot help attaching an interest not at all in themselves--i find the mood represented by only a few almost infantile verses, addressed to a docile little girl of five years, my eldest sister by my mother's second marriage, and my frequent companion, during my illness, in my short walks. to jeanie. sister jeanie, haste, we'll go to whare the white-starred gowans grow, wi' the puddock flower o' gowden hue. the snaw-drap white and the bonny vi'let blue. sister jeanie, haste, we'll go to whare the blossomed lilacs grow-- to whare the pine-tree, dark an' high, is pointing its tap at the cloudless sky. jeanie, mony a merry lay is sung in the young-leaved woods to-day; flits on light wing the dragon-flee, an' bums on the flowrie the big red-bee. down the burnie wirks its way aneath the bending birken spray, an' wimples roun' the green moss-stane, an' mourns. i kenna why, wi' a ceaseless mane. jeanie, come; thy days o' play wi' autumn-tide shall pass away; sune shall these scenes, in darkness cast, be ravaged wild by the wild winter blast. though to thee a spring shall rise, an' scenes as fair salute thine eyes; an' though, through many a cludless day, my winsome jean shall be heartsome and gay; he wha grasps thy little hand nae langer at thy side shall stand, nor o'er the flower-besprinkled brae lead thee the low'nest and the bonniest way. dost thou see yon yard sae green, spreckled wi' mony a mossy stane? a few short weeks o' pain shall fly, an' asleep in that _bed_ shall thy puir brither lie. then thy mither's tears awhile may chide thy joy an' damp thy smile; but sune ilk grief shall wear awa', and i'll be forgotten by ane an' by a'. dinna think the thought is sad; life vexed me aft, but this mak's glad: when cauld my heart and closed my e'e, bonny shall the dreams o' my slumbers be. at length, however, my constitution threw off the malady; though--as i still occasionally feel--the organ affected never quite regained its former vigour; and i began to experience the quiet but exquisite enjoyment of the convalescent. after long and depressing illness, youth itself appears to return with returning health; and it seems to be one of the compensating provisions, that while men of robust constitution and rigid organization get gradually old in their spirits and obtuse in their feelings, the class that have to endure being many times sick have the solace of being also many times young. the reduced and weakened frame becomes as susceptible of the emotional as in tender and delicate youth. i know not that i ever spent three happier months than the autumnal months of this year, when gradually picking up flesh and strength amid my old haunts, the woods and caves. my friend had left me early in july for aberdeen, where he had gone to prosecute his studies under the eye of a tutor, one mr. duncan, whom he described to me in his letters as perhaps the most deeply learned man he had ever seen. "you may ask him a common question," said my friend, "without getting an answer--for he has considerably more than the average absentness of the great scholar about him; but if you inquire of him the state of any one controversy ever agitated in the church or the world, he will give it you at once, with, if you please, all the arguments on both sides." the trait struck me at the time as one of some mark; and i thought of it many years after, when fame had blown the name of my friend's tutor pretty widely as dr. duncan, hebrew professor in our free church college, and one of the most profoundly learned of orientalists. though separated, however, from my friend, i found a quiet pleasure in following up, in my solitary walks, the views which his conversations had suggested; and in a copy of verses, the production of this time, which, with all their poverty and stiffness, please me as true, and as representative of the convalescent feeling, i find direct reference to the beliefs which he had laboured to instil. my verses are written in a sort of metre which, in the hands of collins, became flexible and exquisitely poetic, and which in those of kirke white is at least pleasing, but of which we find poor enough specimens in the "anthologies" of southey, and which perhaps no one so limited in his metrical vocabulary, and so defective in his musical ear, as the writer of these chapters, should ever have attempted. solace. no star of golden influence hailed the birth of him who, all unknown and lonely, pours, as fails the light of eve, his pensive, artless song; yea, those who mark out honour, ease, wealth, fame, as man's sole joys, shall find no joy in him; yet of far nobler kind his silent pleasures prove. for not unmarked by him the ways of men; nor yet to him the ample page unknown, where, traced by nature's hand, is many a pleasing line. oh! when the world's dull children bend the knee, meanly obsequious, to some mortal god, it yields no vulgar joy alone to stand aloof; or when they jostle on wealth's crowded road, and swells the tumult on the breeze, 'tis sweet, thoughtful, at length reclined, to list the wrathful hum. what though the weakly gay affect to scorn the loitering dreamer of life's darkest shade, stingless the jeer, whose voice comes from the erroneous path. scorner, of all thy toils the end declare! if pleasure, pleasure comes uncalled, to cheer the haunts of him who spends his hours in quiet thought. and happier he who can repress desire, than they who seldom mourn a thwarted wish; the vassals they of fate-- the unbending conqueror he, and thou, blest muse, though rudely strung thy lyre, its tones can guile the dark and lonesome day-- can smooth the wrinkled brow, and dry the sorrowing tear. thine many a bliss--oh, many a solace thine! by thee up-held, the soul asserts her throne, the chastened passions sleep, and dove-eyed peace prevails. and thou, fair hope! when other comforts fail-- when night's thick mists descend--thy beacon flames, till glow the dark clouds round with beams of promised bliss. thou failest not, when, mute the soothing lyre, lives thy unfading solace: sweet to raise thy eye, o quiet hope, and greet a friend in heaven!-- a friend, a brother, one whose awful throne in holy fear heaven's mightiest sons approach: man's heart to feel for man-- to save him god's great power! conqueror of death, joy of the accepted soul, oh, wonders raise no doubt when told of thee! thy way past finding out, thy love, can tongue declare? cheered by thy smile, peace dwells amid the storm; held by thy hand, the floods assail in vain; with grief is blent a joy, and beams the vault of death. passing, in one of my walks this autumn, the cave in which i used to spend in boyhood so many happy hours with finlay, i found it smoking, as of old, with a huge fire, and occupied by a wilder and more careless party than even my truant schoolfellows. it had been discovered and appropriated by a band of gipsies, who, attracted by the soot-stains on its roof and sides, and concluding that it had been inhabited by the gipsies of other days, had without consulting factor or landlord, at once entered upon possession, as the proper successors of its former occupants. they were a savage party, with a good deal of the true gipsy blood in them, but not without mixture of a broken-down class of apparently british descent; and one of their women was purely irish. from what i had previously heard about gipsies, i was not prepared for a mixture of this kind; but i found it pretty general, and ascertained that at least one of the ways in which it had taken place was exemplified by the case of the one irish woman. her gipsy husband had served as a soldier, and had married her when in the army. i have been always exceedingly curious to see man in his rude elements--to study him as the savage, whether among the degraded classes of our own country, or, as exhibited in the writings of travellers and voyagers, in his aboriginal state; and i now did not hesitate to visit the gipsies, and to spend not unfrequently an hour or two in their company. they at first seemed jealous of me as a spy; but finding me inoffensive, and that i did not bewray counsel, they came at length to recognise me as the "quiet, sickly lad," and to chatter as freely in my presence as in that of the other pitchers with ears, which they used to fabricate out of tin by the dozen and the score, and the manufacture of which, with the making of horn spoons, formed the main branch of business carried on in the cave. i saw in these visits curious glimpses of gipsy life. i could trust only to what i actually witnessed: what was told me could on no occasion be believed; for never were there lies more gross and monstrous than those of the gipsies; but even the lying formed of itself a peculiar trait. i have never heard lying elsewhere that set all probability so utterly at defiance--a consequence, in part, of their recklessly venturing, like unskilful authors, to expatiate in walks of invention over which their experience did not extend. on one occasion an old gipsy woman, after pronouncing my malady consumption, prescribed for me as an infallible remedy, raw parsley minced small and made up into balls with fresh butter; but seeing, i suppose, from my manner, that i lacked the necessary belief in her specific, she went on to say, that she had derived her knowledge of such matters from her mother, one of the most "skeely women that ever lived." her mother, she said, had once healed a lord's son of a grievous hurt in half a minute, after all the english doctors had shown they could do nothing for him. his eye had been struck out of its socket by a blow, and hung half-way down his cheek; and though the doctors could of course return it to its place, it refused to stick, always falling out again. her mother, however, at once understood the case; and, making a little slit at the back of the young man's neck, she got hold of the end of a sinew, and pulling in the dislodged orb at a tug, she made all tight by running a knot on the controlling ligament, and so kept the eye in its place. and, save that the young lord continued to squint a little, he was well at once. the peculiar anatomy on which this invention was framed must have, of course, resembled that of a wax-doll with winking eyes; but it did well enough for the woman; and, having no character for truth to maintain, she did not hesitate to build on it. on asking her whether she ever attended church, she at once replied, "o yes, at one time very often. i am the daughter of a minister--a _natural_ daughter, you know: my father was the most powerful preacher in all the south, and i always went to hear him." in about an hour after, however, forgetting her extemporary sally, and the reverend character with which she had insisted her sire, she spoke of him, in another equally palpable invention, as the greatest "king of the gipsies" that the gipsies ever had. even the children had caught this habit of monstrous mendacity. there was one of the boys of the band, considerably under twelve, who could extemporize lying narratives by the hour, and seemed always delighted to get a listener; and a little girl, younger still, who "lisped in _fiction_, for the _fiction_ came." there were two things that used to strike me as peculiar among these gipsies--a hindu type of head, small of size, but with a considerable fulness of forehead, especially along the medial line, in the region, as the phrenologist would perhaps say, of _individuality_ and _comparison_; and a singular posture assumed by the elderly females of the tribe in squatting before their fires, in which the elbow rested on the knees brought close together, the chin on the palms, and the entire figure (somewhat resembling in attitude a mexican mummy) assumed an outlandish appearance, that reminded me of some of the more grotesque sculptures of egypt and hindustan. the peculiar type of head was derived, i doubt not, from an ancestry originally different from that of the settled races of the country; nor is it impossible that the peculiar position--unlike any i have ever seen scottish females assume--was also of foreign origin. i have witnessed scenes among these gipsies, of which the author of the "jolly beggars" might have made rare use, but which formed a sort of materials that i lacked the special ability rightly to employ. it was reported on one occasion that a marriage ceremony and wedding were to take place in the cave, and i sauntered the way, in the hope of ascertaining how its inmates contrived to do for themselves what of course no clergyman could venture to do for them--seeing that, of the parties to be united, the bridegroom might have already as many wives living as "peter bell," and the bride as many husbands. a gipsy marriage had taken place a few years previous in a cave near rosemarkie. an old male gipsy, possessed of the rare accomplishment of reading, had half-read, half-spelled the english marriage-service to the young couple, and the ceremony was deemed complete at its close. and i now expected to witness something similar. in an opening in the wood above, i encountered two very drunk gipsies, and saw the first-fruits of the coming merriment. one of the two was an uncouth-looking monster, sallow-skinned, flat-faced, round-shouldered, long and thinly limbed, at least six feet two inches in height, and, from his strange misproportions, he might have passed for seven feet any day, were it not that his trousers, made for a much shorter man, and rising to the middle of his calfless leg, gave him much the appearance of a big boy walking on stilts. the boys of the place called him "giant grimbo;" while his companion, a tight dapper little fellow, who always showed off a compact, well-rounded leg in corduroy inexpressibles, they had learned to distinguish as "billy breeches." the giant, who carried a bagpipe, had broken down ere i came up with them; and now, sitting on the grass, he was droning out in fitful blasts a diabolical music, to which billy breeches was dancing; but, just as i passed, billy also gave way, after wasting an infinity of exertion in keeping erect; and, falling over the prostrate musician, i could hear the bag groaning out its soul as he pressed against it, in a lengthened melancholious squeal. i found the cave bearing an aspect of more than ordinary picturesqueness. it had its two fires, and its double portion of smoke, that went rolling out in the calm like an inverted river; for it clung close to the roof, as if by a reversed gravitation, and turned its foaming surface downwards. at the one fire an old gipsy woman was engaged in baking oaten cakes; and a great pot, that dispensed through the cave the savoury odour of unlucky poultry out short in the middle of their days, and of hapless hares destroyed without the game licence, depended over the other. an ass, the common property of the tribe, stood meditating in the foreground; two urchins, of about from ten to twelve years a-piece--wretchedly supplied in the article of clothing--for the one, provided with only a pair of tattered trousers, was naked from the waist upwards, and the other, furnished with only a dilapidated jacket, was naked from the waist downwards--were engaged in picking up fuel for the fire, still further in front; a few of the ordinary inmates of the place lounged under cover of the smoke, apparently in a mood not in the least busy; and on a couch of dried fern sat evidently the central figure of the group, a young, sparkling-eyed brunette, more than ordinarily marked by the hindu peculiarities of head and feature, and attended by a savage-looking fellow of about twenty, dark as a mulatto, and with a profusion of long flexible hair, black as jet, hanging down to his eyes, and clustering about his cheeks and neck. these were, i ascertained, the bride and bridegroom. the bride was engaged in sewing a cap--the bridegroom in watching the progress of the work. i observed that the party, who were less communicative than usual, seemed to regard me in the light of an intruder. an elderly tinker, the father of the bride, grey as a leafless thorn in winter, but still stalwart and strong, sat admiring a bit of spelter of about a pound weight. it was gold, he said, or, as he pronounced the word, "guild," which had been found in an old cairn, and was of immense value, "for it was peer guild and that was the best o' guild;" but if i pleased, he would sell it to me, a very great bargain. i was engaged with some difficulty in declining the offer, when we were interrupted by the sounds of the bagpipe. giant grimbo and billy breeches had succeeded in regaining their feet, and were seen staggering towards the cave. "where's the whisky, billy!" inquired the proprietor of the gold, addressing himself to the man of the small clothes. "whisky!" said billy, "ask grimbo." "where's the whisky, grimbo?" reiterated the tinker. "whisky!" replied grimbo, "whisky!" and yet again, after a pause and a hiccup, "whisky!" "ye confounded blacks!" said the tinker, springing to his feet with an agility wonderful for an age so advanced as his, "have you drunk it all? but take that, grimbo," he added, planting a blow full on the side of the giant's head, which prostrated his vast length along the floor of the cave. "and take that, billy," he iterated, dealing such another blow to the shorter man, which sent him right athwart his prostrate comrade. and then, turning to me, he remarked with perfect coolness, "that, master, i call smart hitting." "honest lad," whispered one of the women immediately after, "it will be a _reugh_ time wi' us here the nicht: you had just better be stepping your ways." i had already begun to think so without prompting; and so, taking my leave of the gipsies, i failed being, as i had proposed, one of the witnesses of the wedding. there is a sort of grotesque humour in scenes of the kind described, that has charms for artists and authors of a particular class--some of them men of broad sympathies and great genius; and hence, through their representations, literary and pictorial, the ludicrous point of view has come to be the conventional and ordinary one. and yet it is a sad enough merriment, after all, that has for its subject a degradation so extreme. i never knew a gipsy that seemed to possess a moral sense--a degree of _pariahism_ which has been reached by only one other class in the country, and that a small one--the descendants of degraded females in our large towns. an education in scotland, however secular in its character, always casts a certain amount of enlightenment on the conscience; a home, however humble, whose inmates win their bread by honest industry, has a similar effect; but in the peculiar walks in which for generations there has been no education of any kind, or in which bread has been the wages of infamy, the moral sense seems so wholly obliterated, that there appears to survive nothing in the mind to which the missionary or the moralist can appeal. it seems scarce possible for a man to know even a very little of these classes, without learning, in consequence, to respect honest labour, and even secular knowledge, as at least the _second-best_ things, in their moral bearing and influence, that can exist among a people. chapter xviii. "for such is the flaw or the depth of the plan in the make of that wonderful creature called man, no two virtues, whatever relation they claim, nor even two different shades of the same. though like as was ever twin-brother to brother. possessing the one shall imply you've the other."--burns. during my period of convalescence, i amused myself in hewing for my uncles, from an original design, an ornate dial-stone; and the dial-stone still exists, to show that my skill as a stone-cutter rose somewhat above the average of the profession in those parts of the country in which it ranks highest. gradually as i recovered health and strength, little jobs came dropping in. i executed sculptured tablets in a style not common in the north of scotland; introduced into the churchyards of the locality a better type of tombstone than had obtained in them before, save, mayhap, at a very early period; distanced all my competitors in the art of inscription-cutting; and at length found that, without exposing my weakened lungs to the rough tear and wear to which the ordinary stone-cutter must subject himself, i could live. i deemed it an advantage, too, rather than the reverse, that my new branch of employment brought me not unfrequently for a few days into country districts sufficiently distant from home to present me with new fields of observation, and to open up new tracts of inquiry. sometimes i spent half a week in a farm-house in the neighbourhood of some country churchyard--sometimes i lodged in a village--oftener than once i sheltered beside some gentleman's seat, where the august shadow of lairdship lay heavy on society; and in this way i came to see and know a good deal of the scottish people, in their many-coloured aspects, of which otherwise i might have remained ignorant. at times, too, on some dusty cottage shelf i succeeded in picking up a rare book, or, what was not less welcome, got a curious tradition from the cottager; or there lay within the reach of an evening walk some interesting piece of antiquity, or some rock-section, which i found it profitable to visit. a solitary burying-ground, too, situated, as country burying-grounds usually are, in some pleasant spot, and surrounded by its groups of ancient trees, formed a much more delightful scene of labour than a dusty work-shed, or some open area in a busy town; and altogether i found my new mode of life a quiet and happy one. nor, with all its tranquillity, was it a sort of life in which the intellect was in any great danger of falling asleep. there was scarce a locality in which new game might not be started, that, in running down, kept the faculties in full play. let me exemplify by describing the courses of inquiry, physical and metaphysical, which opened up to me when spending a few days, first in the burying-ground of kirkmichael, and next in the churchyard of nigg. i have elsewhere somewhat fancifully described the ruinous chapel and solitary grave-yard of kirkmichael as lying on the sweep of a gentle declivity, within a few yards of a flat sea-beach, so little exposed to the winds, that it would seem as if "ocean muffled its waves in approaching this field of the dead." and so the two vegetations--that of the land and of the sea--undisturbed by the surf, which on opener coasts prevents the growth of either along the upper littoral line, where the waves beat heaviest, here meet and mingle, each encroaching for a little way on the province of the other. and at meal-times, and when returning homewards in the evening along the shore, it furnished me with amusement enough to mark the character of the several plants of both floras that thus meet and cross each other, and the appearances which they assume when inhabiting each the other's province. on the side of the land, beds of thrift, with its gay flowers the sea-pinks, occupied great prominent cushions, that stood up like little islets amid the flowing sea, and were covered over by salt water during stream-tides to the depth of from eighteen inches to two feet. with these there occasionally mingled spikes of the sea-lavender; and now and then, though more rarely, a _sea-aster_, that might be seen raising above the calm surface its composite flowers, with their bright yellow staminal pods, and their pale purple petals. far beyond, however, even the cushions of thrift, i could trace the fleshy, jointed stems of the glass-wort, rising out of the mud, but becoming diminutive and branchless as i followed them downwards, till at depths where they must have been frequently swum over by the young coal-fish and the flounder, they appeared as mere fleshy spikes, scarce an inch in height, and then ceased. on the side of the sea it was the various fucoids that rose highest along the beach: the serrated focus barely met the salt-wort; but the bladder-bearing fucus (_fucus nodosus_) mingled its brown fronds not unfrequently with the crimson flowers of the thrift, and the vesicular fucus (_fucus vesiculosus_) rose higher still, to enter into strange companionship with the sea-side plantains and the common scurvy-grass. green enteromorpha of two species--_e. compressa_ and _e. intestinalis_--i also found abundant along the edges of the thrift-beds; and it struck me as curious at the time, that while most of the land-plants which had thus descended beyond the sea-level were of the high dicotyledonous division, the sea-weeds with which they mingled their leaves and seed-vessels were low in their standing--fuci and enteromorpha--plants at least not higher than their kindred cryptogamia, the lichens and mosses of the land. far beyond, in the outer reaches of the bay, where land-plants never approached, there were meadows of a submarine vegetation, of (for the sea) a comparatively high character. their numerous plants (_zostera marina_) had true roots, and true leaves, and true flowers; and their spikes ripened amid the salt waters towards the close of autumn, round white seeds, that, like many of the seeds of the land, had their sugar and starch. but these plants kept far aloof, in their green depths, from their cogeners the monocotyledons of the terrestrial flora. it was merely the low _fucaceæ_ and _conferveæ_ of the sea that i found meeting and mixing with the descending dicotyledons of the land. i felt a good deal of interest in marking, about this time, how certain belts of marine vegetation occurred on a vast boulder situated in the neighbourhood of cromarty, on the extreme line of the ebb of spring-tides. i detected the various species ranged in zones, just as on lofty hills the botanist finds his agricultural, moorland, and alpine zones rising in succession the one over the other. at the base of the huge mass, at a level to which the tide rarely falls, the characteristic vegetable is the rough-stemmed tangle--_laminaria digitata_. in the zone immediately above the lowest, the prevailing vegetable is the smooth-stemmed tangle--_laminaria saccharina_. higher still there occurs a zone of the serrated fucus--_f. serratus_--blent with another familiar fucus--_f. nodosus_. then comes a yet higher zone of _fucus vesiculosus_; and higher still, a few scattered tufts of _fucus canaliculatus_; and then, as on lofty mountains that rise above the line of perpetual snow, vegetation ceases, and the boulder presents a round bald head, that rises over the surface after the first few hours of ebb have passed. but far beyond its base, where the sea never falls, green meadows of _zostera_ flourish in the depths of the water, where they unfold their colourless flowers, unfurnished with petals, and ripen their farinaceous seeds, that, wherever they rise to the surface, seem very susceptible of frost. i have seen the shores strewed with a line of green _zostera_, with its spikes charged with seed, after a smart october frost, that had been coincident with the ebb of a low spring-tide, had nipt its rectilinear fronds and flexible stems. but what, it may be asked, was the bearing of all this observation? i by no means saw its entire bearing at the time: i simply observed and recorded, because i found it pleasant to observe and record. and yet one of the wild dreams of maillet in his _telliamed_ had given a certain degree of unity, and a certain definite direction, to my gleanings of fact on the subject, which they would not have otherwise possessed. it was held by this fanciful writer, that the vegetation of the land had been derived originally from that of the ocean. "in a word," we find him saying, "do not herbs, plants, roots, grains, and all of this kind that the earth produces and nourishes, come from the sea? is it not at least natural to think so, since we are certain that all our habitable lands came originally from the sea? besides, in small islands far from the continent, which have appeared a few ages ago at most, and where it is manifest that never any men had been, we find shrubs, herbs, and roots. now, you must be forced to own that either those productions owed their origin to the sea, _or to a new creation, which is absurd_." and then maillet goes on to show, after a manner which--now that algaeology has become a science--must be regarded as at least curious, that the plants of the sea, though not so well developed as those of the land, are really very much of the same nature. "the fishermen of marseilles find daily," he says, "in their nets, and among their fish, plants of a hundred kinds, with their fruits still upon them; and though these fruits are not so large nor so well nourished as those of our earth, yet their species is in no other respects dubious. there they find clusters of white and black grapes, peach-trees, pear-trees, prune-trees, apple-trees, and all sorts of flowers." such was the sort of wild fable invented in a tract of natural science in which i found it of interest to acquaint myself with the truth. i have since seen the extraordinary vision of maillet revived, first by oken, and then by the author of the "vestiges of creation;" and when, in grappling with some of the views and statements of the latter writer, i set myself to write the chapter of my little work which deals with this special hypothesis, i found that i had in some sort studied in the school in which the education necessary to its production was most thoroughly to be acquired. had the ingenious author of the "vestiges" taken lessons for but a short time at the same form, he would scarce have thought of reviving in those latter ages the dream of oken and maillet. a knowledge of the facts would to a certainty have protected him against the reproduction of the hypothesis. the lesson at nigg was of a more curious kind, though, mayhap, less certainly conclusive in its bearings. the house of the proprietor of nigg bordered on the burying-ground. i was engaged in cutting an inscription on the tombstone of his wife, recently dead; and a poor idiot, who found his living in the kitchen, and to whom the deceased had shown kindness; used to come every day to the churchyard, to sit beside me, and jabber in broken expressions his grief. i was struck with the extremeness of his idiocy: he manifested even more than the ordinary inability of his class to deal with figures, for he could scarce tell whether nature had furnished him with one head or with two; and no power of education could have taught him to count his fingers. he was equally defective, too, in the mechanical. angus could not be got into trousers; and the contrivance of the button remained a mystery which he was never able to comprehend. and so he wore a large blue gown, like that of a beadsman, which slipped over his head, and was bound by a belt round his middle, with a stout woollen shirt underneath. but, though unacquainted with the mystery of the button, there were mysteries of another kind with which he seemed to have a most perfect acquaintance: angus--always a faithful attendant at church--was a great critic in sermons; nor was it every preacher that satisfied him; and such was his imitative turn, that he himself could preach by the hour, in the manner--so far at least as voice and gesture went--of all the popular ministers of the district. there was, however, rather a paucity of idea in his discourses: in his more energetic passages, when he struck the book and stamped with his foot, he usually iterated, in sonorous gaelic--"the wicked, the wicked, o wretches the wicked!" while a passage of a less depreciatory character served him for setting off his middle tones and his pathos. but that for which his character was chiefly remarkable was an instinctive, foxlike cunning, that seemed to lie at its very basis--a cunning which co-existed, however, with perfect honesty, and a devoted attachment to his patron the proprietor. the town of cromarty had its poor imbecile man of quite a different stamp. jock gordon had been, it was said, "like other people" till his fourteenth year, when a severe attack of illness left him bankrupt in both mind and body. he rose from his bed lame of a foot and hand, his one side shrunken and nerveless, the one lobe of his brain apparently inoperative, and with less than half his former energy and intellect; not at all an idiot, however, though somewhat more helpless--the poor mutilated fragment of a reasoning man. among his other failings, he stuttered lamentably. he became an inmate of the kitchen of cromarty house; and learned to run, or, i should rather say, to _limp_, errands--for he had risen from the fever that ruined him to run no more--with great fidelity and success. he was fond of church-going, of reading good little books, and, notwithstanding his sad stutter, of singing. during the day, he might be heard, as he hobbled along the streets on business, "_singing in into himself_," as the children used to say, in a low unvaried under-tone, somewhat resembling the humming of a bee; but when night fell, the whole town heard him. he was no patronizer of modern poets or composers. "there was a ship, and a ship of fame," and "death and the fair lady," were his especial favourites; and he could repeat the "gosport tragedy," and the "babes in the wood," from beginning to end. sometimes he stuttered in the notes, and then they lengthened on and on into a never-ending quaver that our first-rate singers might have envied. sometimes there was a sudden break--jock had been consulting the pocket in which he stored his bread; but no sooner was his mouth half-cleared than he began again. in middle-life, however, a great calamity overtook jock. his patron, the occupant of cromarty house, quitted the country for france: jock was left without occupation or aliment; and the streets heard no more of his songs. he grew lank and thin, and stuttered and limped more painfully than before, and was in the last stage of privation and distress; when the benevolent proprietor of nigg, who resided half the year in a town-house in cromarty, took pity upon him, and introduced him to his kitchen. and in a few days jock was singing and limping errands with as much energy as ever. but the time at length came when his new benefactor had to quit his house in town for his seat in the country; and it behoved jock to take temporary leave of cromarty, and follow him. and then the poor imbecile man of the town-kitchen had, of course, to measure himself against his formidable rival, the vigorous idiot of the country one. on jock's advent at nigg--which had taken place a few weeks previous to my engagement in the burying-ground of the parish--the character of angus seemed to dilate in energy and power. he repaired to the churchyard with spade and pickaxe, and began digging a grave. it was a grave, he said, for wicked jock gordon; and jock, whether he thought it or no, had come to nigg, he added, only to be buried. jock, however, was not to be dislodged so; and angus, professing sudden friendship for him, gave expression to the magnanimous resolution, that he would not only tolerate jock, but also be very kind to him, and show him the place where he kept all his money. he had lots of money, he said, which he had hidden in a dike; but he would show the place to jock gordon--to poor cripple jock gordon: he would show him the very hole, and jock would get it all. and so he brought jock to the hole--a cavity in a turf-wall in the neighbouring wood--and, taking care that his own way of retreat was clear, he bade him insinuate his hand. no sooner had he done so, however, than there issued forth from between his fingers a cloud of wasps, of the variety so abundant in the north country, that build their nests in earthy banks and old mole-hills; and poor jock, ill fitted for retreat in any sudden emergency, was stung within an inch of his life. angus returned in high glee, preaching about "wicked jock gordon, whom the very wasps wouldn't let alone;" but though he pretended no further friendship for a few days after, he again drew to him in apparent kindness; and on the following saturday, on jock being despatched to a neighbouring smithy with a sheep's head to singe, angus volunteered his services to show him the way. angus went trotting before; jock came limping behind: the fields were open and bare; the dwellings few and far between; and after having passed, in about an hour's walking, half-a-dozen little hamlets, jock began to marvel exceedingly that there should be no sign of the smith's shop. "poor foolish jock gordon!" ejaculated angus, quickening his trot into a canter; "what does he know about carrying sheep's heads to the smithy?" jock laboured hard to keep up with his guide; quavering and semi-quavering, as his breath served--for jock always began to sing, when in solitary places, after nightfall, as a protection against ghosts. at length the daylight died entirely away, and he could only learn from angus that the smithy was further off than ever; and, to add to his trouble and perplexity, the roughness of the ground showed him that they were wandering from the road. first they went toiling athwart what seemed an endless range of fields, separated from one another by deep ditches and fences of stone; then they crossed over a dreary moor, bristling with furze and sloe-thorn; then over a waste of bogs and quagmires; then across a track of newly-ploughed land; and then they entered a second wood. at length, after a miserable night's wandering, day broke upon the two forlorn satyrs; and jock found himself in a strange country, with a long narrow lake in front and a wood behind. he had wandered after his guide into the remote parish of tarbet. tarbet abounded at that time in little muddy lakes, edged with water-flags and reeds, and swarming with frogs and eels; and it was one of the largest and deepest of these that now lay before jock and his guide. angus tucked up his blue gown, as if to wade across. jock would have as soon thought of fording the german ocean. "oh, wicked jock gordon!" exclaimed the fool, when he saw him hesitate; "the colonel's waiting, poor man, for his head, and jock will no' take it to the smithy." he stepped into the water. jock followed in sheer desperation; and, after clearing the belt of reeds, both sank to the middle in the mingled water and mud. angus had at length accomplished the object of his journey. extricating himself in a moment--for he was lithe and active--he snatched the sheep's head and trotters from jock, and, leaping ashore, left the poor man sticking fast. it was church-time ere he reached, on his way back, the old abbey of fearn, still employed as a protestant place of worship; and as the sight of the gathering people awakened his church-going propensity, he went in. he was in high spirits--seemed, by the mouths he made, very much to admire the sermon, and paraded the sheep's head and trotters through the passages and gallery a score of times at least, like a monk of the order of st. francis exhibiting the relics of some favourite saint. in the evening he found his way home, but learned, to his grief and astonishment, that "wicked jock gordon" had got there shortly before him in a cart. the poor man had remained sticking in the mud for three long hours after angus had left him, until at length the very frogs began to cultivate his acquaintance, as they had done that of king log of old; and in the mud he would have been sticking still, had he not been extricated by a farmer of fearn, who, in coming to church, had taken the lake in his way. he left nigg, however, for cromarty on the following day, convinced that he was no match for his rival, and dubious how the next adventure might terminate. such was the story which i found current in nigg, when working in its churchyard, with the hero of the adventure often beside me. it led me to take special note of his class, and to collect facts respecting them, on which i erected a sort of semi-metaphysical theory of human character, which, though it would not now be regarded as by any means a novel one, i had thought out for myself, and which possessed for me, in consequence, the charm of originality. in these poor creatures, i thus argued, we find, amid much general dilapidation and brokenness of mind, certain instincts and peculiarities remaining entire. here, in angus, for instance, there is that instinctive cunning which some of the lower animals, such as the fox, possess, existing in a wonderful degree of perfection. pope himself, who "could not drink tea without a stratagem," could scarce have possessed a larger share of it. and yet how distinct must not this sort of ingenuity be from the mechanical ingenuity! angus cannot fix a button in its hole. i even see him baffled by a tall snuff-box, with a small quantity of snuff at its bottom, that lies beyond the reach of his finger. he has not ingenuity enough to lay it on its side, or to empty its snuff on his palm; but stretches and ever stretches towards it the unavailing digit, and then gets angry to find it elude his touch. there are other idiots, however, who have none of angus's cunning, in whom this mechanical ability is decidedly developed. many of the _crétins_ of the alps are said to be remarkable for their skill as artisans; and it is told of a scotch idiot, who lived in a cottage on the maolbuie common in the upper part of the black isle, and in whom a similar mechanical ability existed, abstracted from ability of almost every other kind, that, among other things, he fabricated, out of a piece of rude metal, a large sacking needle. angus is attached to his patron, and mourns for the deceased lady; but he seems to have little general regard for the species--simply courting for the time those from whom he expects snuff. the cromarty idiot, on the contrary, is obliging and kindly to all, and bears a peculiar love to children; and, though more an imbecile in some respects than even angus, he has a turn for dress, and can attire himself very neatly. in this last respect, however, the cromarty fool was excelled by an idiot of the last age, known to the children of many a village and hamlet as fool charloch, who used to go wandering about the country, adorned, somewhat in the style of an indian chief, with half a peacock's tail stuck in his cap. yet another idiot, a fierce and dangerous creature, seemed as invariably malignant in his dispositions as the cromarty one is benevolent, and died in a prison, to which he was committed for killing a poor half-witted associate. yet another idiot of the north of scotland had a strange turn for the supernatural. he was a mutterer of charms, and a watcher of omens, and possessed, it was said, the second sight. i collected not a few other facts of a similar kind, and thus reasoned regarding them:-- these idiots are imperfect men, from whose minds certain faculties have been effaced, and other faculties left to exhibit themselves, all the more prominently from the circumstances of their standing so much alone. they resemble men who have lost their hands, but retain their feet, or who have lost their sight or smell, but retain their taste and hearing. but as the limbs and the senses, if they did not exist as separate parts of the frame, could not be separately lost, so in the mind itself, or in at least the organization through which the mind manifests itself, there must also be separate parts, or they would not be thus found isolated by nature in her mutilated and abortive specimens. those metaphysicians who deal by the mind as if it were simply a general power existing in _states_, must be scarce less in error than if they were to regard the _senses_ as merely a general power existing in states, instead of recognising them as distinct, independent powers, so various often in their degree of development, that, from the full perfection of any one of them, the perfection, or even the existence, of any of the others cannot be predicated. if, for instance, it were--as some physicians hold--the same general warmth of emotive power that glows in benevolence and burns in resentment, the fierce, dangerous idiot that killed his companion, and the kindly-dispositioned cromarty one who takes home pailfuls of water to the poor old women of the place, and parts with his own toys to its children, would, instead of thus exhibiting the opposite poles of character, at least so far resemble one another, that the vindictive fool would at times be kindly and obliging, and the benevolent one at times violent and resentful. but such is not the case: the one is never madly savage--the other never genial and kind; and so it seems legitimate to infer, that it is not a general power or energy that acts through them in different states, but two particular powers or energies, as unlike in their natures, and as capable of acting apart, as seeing and hearing. even powers which seem to have so much in common, that the same words are sometimes made use of in reference to both, may be as distinct as smelling and tasting. we speak of the _cunning_ workman, and we speak of the _cunning_ man; and refer to a certain faculty of contrivance manifested in dealing with characters and affairs on the part of the one, and in dealing with certain modifications of matter on the part of the other; but so entirely different are the two faculties, and, further, so little dependent are they, in at least their first elements, on intellect, that we may find the cunning which manifests itself in affairs, existing, as in angus, totally dissociated from mechanical skill; and, on the other hand, the cunning of the artisan, existing, as in the idiot of the maolbuie, totally dissociated from that of the diplomatist. in short, regarding idiots as persons of fragmentary mind, in whom certain primary mental elements may be found standing out in a state of great entireness, and all the more striking in their relief from the isolation, i came to view them as _bits of analysis_, if i may so express myself, made to my hand by nature, and from the study of which i could conceive of the structure of minds of a more complete, and therefore more complex character. as children learn the alphabet from cards, each of which contains only a letter or two a-piece, printed large, i held at this time, and, with a few modifications, hold still, that those primary sentiments and propensities which form the basis of character, may be found separately stamped in the same way on the comparatively blank minds of the imbecile; and that the student of mental philosophy might learn from them what may be regarded as the alphabet of his science, much more truthfully than from those metaphysicians who represent mind as a power not manifested in contemporaneous and separable faculties, but as existing in consecutive states. cromarty had been fortunate in its parish ministers. from the death of its last curate, shortly after the revolution, and, the consequent return of its old "outed minister," who had resigned his living for conscience' sake, twenty-eight years before, and now came to spend his evening of life with his people, it had enjoyed the services of a series of devout and popular men; and so the cause of the establishment was particularly strong in both town and parish. at the beginning of the present century cromarty had not its single dissenter; and though a few of what were known as "haldane's people" might be found in it, some eight or ten years later they failed in effecting a lodgment, and ultimately quitted it for a neighbouring town. almost all the dissent that has arisen in scotland since the revolution has been an effect of moderatism and forced settlements; and as the place had known neither, its people continued to harbour within the church of their fathers, nor wished to change. a vacancy had occurred in the incumbency, during my sojourn in the south, through the death of the incumbent, the respected minister of my childhood and youth; and i found, on my return, a new face in the pulpit. it was that of a remarkable man--the late mr. stewart of cromarty--one of at once the most original thinkers and profound theologians i ever knew; though he has, alas! left as little mark of his exquisite talent behind him, as those sweet singers of former ages, the memory of whose enchanting notes has died, save as a doubtful echo, with the generation that heard them. i sat, with few interruptions, for sixteen years under his ministry; and for nearly twelve of these enjoyed his confidence and friendship. i never could press myself on the notice of superior men, however desirous of forming their acquaintance; and have, in consequence, missed opportunities innumerable of coming in friendly contact with persons whom it would be at once a pleasure and an honour to know. and so, for the first two years, or rather more, i was content to listen with profound attention to the pulpit addresses of my new minister, and to appear as a catechumen, when my turn came, at his diets of catechising. he had been struck, however, as he afterwards told me, by my sustained attention when at church; and, on making inquiry regarding me among his friends, he was informed that i was a great reader, and, it was believed, a writer of verse. and coming unwittingly out upon him one day as he was passing, when quitting my work-place for the street, he addressed me "well, lad," he said, "it is your dinner hour: i hear i have a poet among my people?" "i doubt it much," i replied. "well," he rejoined, "one may fall short of being a poet, and yet gain by exercising one's tastes and talents in the poetic walk. the accomplishment of verse is at least not a vulgar one." the conversation went on as we passed together along the street; and he stood for a time opposite the manse door. "i am forming," he said, "a small library for our sabbath-school scholars and teachers: most of the books are simple enough little things; but it contains a few works of the intellectual class. call upon me this evening that we may look over them, and you may perhaps find among them some volumes you would wish to read." i accordingly waited upon him in the evening; and we had a long conversation together. he was, i saw, curiously sounding me, and taking my measure in all directions; or, as he himself afterwards used to express it in his characteristic way, he was like a traveller who, having come unexpectedly on a dark pool in a ford, dips down his staff, to ascertain the depth of the water and the nature of the bottom. he inquired regarding my reading, and found that in the belles-lettres, especially in english literature, it was about as extensive as his own. he next inquired respecting my acquaintance with the metaphysicians. "had i read reid?" "yes." "brown?" "yes." "_hume?_" "yes." "ah! ha! hume!! by the way, has he not something very ingenious about miracles? do you remember his argument?" i stated the argument. "ah, very ingenious--most ingenious. and how would you answer that?" i said, "i thought i could give an abstract of the reply of campbell," and sketched in outline the reverend doctor's argument. "and do you deem that satisfactory?" said the minister. "no, not at all," i replied. "no! no! _that's_ not satisfactory." "but perfectly satisfactory," i rejoined, "that such is the general partiality for the better side, that the worse argument has been received as perfectly adequate for the last sixty years." the minister's face gleamed with the broad fun that entered so largely into his composition, and the conversation shifted into other channels. from that night forward i enjoyed perhaps more of his confidence and conversation than any other man in his parish. many an hour did he spend beside me in the churchyard, and many a quiet tea did i enjoy in the manse; and i learned to know how much solid worth and true wisdom lay under the somewhat eccentric exterior of a man who sacrificed scarce anything to the conventionalities. this, with the exception of chalmers, sublimest of scottish preachers--for, little as he was known, i will challenge for him that place--was a genial man, who, for the sake of a joke, would sacrifice anything save principle; but, though marvellously careless of maintaining intact the "gloss of the clerical enamel," never was there sincerity more genuine than his, or a more thorough honesty. content to be in the right, he never thought of simulating it, and sacrificed even less than he ought to appearances. i may mention, that on coming to edinburgh, i found the peculiar taste formed under the ministrations of mr. stewart most thoroughly gratified under those of dr. guthrie; and that in looking round the congregation, i saw, with pleasure rather than surprise, that all mr. stewart's people resident in edinburgh had come to the same conclusion; for there--sitting in the doctor's pews--they all were. certainly in fertility of illustration, in soul-stirring, evangelistic doctrine, and in a general basis of rich humour, the resemblance between the deceased and the living minister seems complete; but genius is always unique; and while in breadth of popular power dr. guthrie stands alone among living preachers, i have never either heard or read argument in the analogical field that in ingenuity or originality equalled that of mr. stewart. that in which he specially excelled all the men i ever knew was the power of detecting and establishing occult resemblances. he seemed able to read off, as if by intuition--not by snatches and fragments, but as a consecutive whole--that old revelation of type and symbol which god first gave to man; and when privileged to listen to him, i have been constrained to recognise, in the evident integrity of the reading, and the profound and consistent theological system which the pictorial record conveyed, a demonstration of the divinity of its origin, not less powerful and convincing than the demonstrations of the other and more familiar departments of the christian evidences. compared with other theologians in this province, i have felt under his ministry as if, when admitted to the company of some party of modern _savans_ employed in deciphering a hieroglyphic covered obelisk of the desert, and here successful in discovering the meaning of an insulated sign, and there of a detached symbol, we had been suddenly joined by some sage of the olden time, to whom the mysterious inscription was but a piece of common language written in a familiar alphabet, and who could read off fluently, and as a whole, what the others could but darkly guess at in detached and broken parts. to this singular power of tracing analogies there was added in mr. stewart an ability of originating the most vivid illustrations. in some instances a sudden stroke produced a figure that at once illuminated the subject-matter of his discourse, like the light of a lanthorn flashed hastily upon a painted wall; in others he dwelt upon an illustrative picture, finishing it with stroke after stroke, until it filled the whole imagination, and sank deep into the memory. i remember hearing him preach, on one occasion, on the return of the jews as a people to him whom they had rejected, and the effect which their sudden conversion could not fail to have on the unbelieving and gentile world. suddenly his language, from its high level of eloquent simplicity, became that of metaphor, "when joseph," he said, "shall reveal himself to his _brethren_, the _whole house of pharaoh shall hear the weeping_." on another occasion i heard him dwell on that vast profundity, characteristic of the scriptural revelation of god, which ever deepens and broadens the longer and more thoroughly it is explored, until at length the student--struck at first by its expansiveness, but conceiving of it as if it were a mere _measured_ expansiveness--finds that it partakes of the unlimited infinity of the divine nature itself. naturally and simply, as if growing out of the subject, like a berry-covered mistletoe out of the massy trunk of an oak, there sprung up one of his more lengthened illustrations. a child bred up in the interior of the country has been brought for the first time to the sea-shore, and carried out into the middle of one of the noble firths that indent so deeply our line of coast. and, on his return, he describes to his father, with all a child's eagerness, the wonderful expansiveness of the _ocean_ which he had seen. he went out, he tells him, far amid the great waves and the rushing tides, until at length the hills seemed diminished into mere hummocks, and the wide land itself appeared along the waters but as a slim strip of blue. and then, when in mid-sea, the sailors heaved the lead; and it went down, and down, and down, and the long line slipped swiftly away, coil after coil, till, ere the plummet rested on the ooze below, all was well-nigh expended. and was it not the great sea, asks the boy, that was so vastly broad, and so profoundly deep? ah! my child, exclaims the father, you have not seen aught of its greatness: you have sailed over merely one of its little arms. had it been out into the wide ocean that the seamen had carried you, "you would have _seen_ no shore, and you would have _found_ no bottom." in one rare quality of the orator mr. stewart stood alone among his contemporaries. pope refers to a strange power of creating love and admiration by "just touching the brink of all we hate." and burke, in some of his nobler passages, happily exemplifies the thing. he intensified the effect of his burning eloquence by the employment of figures so homely--nay, almost so repulsive--that the man of lower powers who ventured on their use would find them effective in but lowering his subject, and ruining his cause. i need but refer, in illustration, to the well-known figure of the disembowelled bird, which occurs in the indignant denial that the character of the revolutionary french in aught resembled that of the english. "we have not," says the orator, "been drawn and trussed, in order that we may be filled, like stuffed birds in a museum, with chaff, and rags, and paltry blurred shreds of paper about the rights of man." into this perilous but singularly effective department, closed against even superior men, mr. stewart could enter safely and at will. one of the last sermons i heard him preach--a discourse of singular power--was on the "sin-offering" of the jewish economy, as minutely described in leviticus. he drew a picture of the slaughtered animal, foul with dust and blood, and streaming, in its impurity, to the sun, as it awaited the consuming fire amid the uncleanness of ashes outside the camp--its throat gashed across--its entrails laid open; a vile and horrid thing, which no one could see without experiencing emotions of disgust, nor touch without contracting defilement. the description appeared too painfully vivid--its introduction too little in accordance with the rules of a just taste. but the master in this difficult walk knew what he was doing. and that, he said, pointing to the strongly-coloured picture he had just completed--"and that is sin." by one stroke the intended effect was produced, and the rising disgust and horror transferred from the revolting material image to the great moral evil. how could such a man pass from earth, and leave no trace behind him? mainly, i believe, from two several causes. as the minister of an attached provincial congregation, a sense of duty, and the promptings of a highly intellectual nature, to which exertion was enjoyment, led him to study much and deeply; and he poured forth _viva voce_ his full-volumed and ever-sparkling tide of eloquent idea, as freely and richly as the nightingale, unconscious of a listener, pours forth her melody in the shade. but, strangely diffident of his own powers, he could not be made to believe that what so much impressed and delighted the privileged few who surrounded him, was equally suited to impress and delight the intellectual many outside; or that he was fitted to speak through the press in tones which would compel the attention, not merely of the religious, but also of the literary world. further, practising but little the art of elaborate composition, and master of a spoken style more effective for the purposes of the pulpit than almost any written one, save that of chalmers, he failed, in all his attempts in writing, to satisfy a fastidious taste, which he had suffered greatly to outgrow his ability of production. and so he failed to leave any adequate mark behind him. i find that for my stock of theological idea, not directly derived from scripture, i stand more indebted to two scotch theologians than to all other men of their profession and class. the one of these was thomas chalmers--the other, alexander stewart: the one a name known wherever the english language is spoken; while of the other it is only remembered, and by comparatively a few, that the impression did exist at the time of his death, that "a mighty spirit was eclipsed--a power had passed from day to darkness, to whose hour of light no likeness was bequeathed--no name." chapter xix. "see yonder poor o'er-labour'd wight, so abject, mean, and vile, who begs a brother of the earth to give him leave to toil; and see his lordly _fellow-worm_ the poor petition spurn."--burns. work failed me about the end of june ; and, acting on the advice of a friend who believed that my style of cutting inscriptions could not fail to secure for me a good many little jobs in the churchyards of inverness, i visited that place, and inserted a brief advertisement in one of the newspapers, soliciting employment. i ventured to characterize my style of engraving as neat and _correct_; laying especial emphasis on the correctness, as a quality not very common among the stone-cutters of the north. it was not a scotch, but an english mason, who, when engaged, at the instance of a bereaved widower, in recording on his wife's tombstone that a "virtuous woman is a _crown_ to her husband," corrupted the text, in his simplicity, by substituting " s." for the "_crown_." but even scotch masons do make odd enough mistakes at times, especially in the provinces; and i felt it would be something gained could i but get an opportunity of showing the inverness public that i had at least english enough to avoid the commoner errors. my verses, thought i, are at least tolerably correct: could i not get some one or two copies introduced into the poet's corner of the _inverness courier_ or _journal_, and thus show that i have literature enough to be trusted with the cutting of an epitaph on a gravestone? i had a letter of introduction from a friend in cromarty to one of the ministers of the place, himself an author, and a person of influence with the proprietors of the _courier_; and, calculating on some amount of literary sympathy from a man accustomed to court the public through the medium of the press, i thought i might just venture on stating the case to him. i first, however, wrote a brief address, in octo-syllabic quatrains, to the river which flows through the town, and gives to it its name;--a composition which has, i find, more of the advertisement in it than is quite seemly, but which would have perhaps expressed less confidence had it been written less under the influence of a shrinking timidity, that tried to reassure itself by words of comfort and encouragement. i was informed that the minister's hour for receiving visitors of the humbler class was between eleven and twelve at noon; and, with the letter of introduction and my copy of verses in my pocket, i called at the manse, and was shown into a little narrow ante-room, furnished with two seats of deal that ran along the opposite walls. i found the place occupied by some six or seven individuals--more than half their number old withered women, in very shabby habiliments, who, as i soon learned from a conversation which they kept up in a grave under-tone, about weekly allowances, and the partialities of the session, were paupers. the others were young men, who had apparently serious requests to prefer anent marriage and baptism; for i saw that one of them was ever and anon drawing from his breast-pocket a tattered copy of the shorter catechism, and running over the questions; and i overheard another asking his neighbour "who drew up the contract lines for him," and "where he had got the whisky." the minister entered; and as he passed into the inner room, we all rose. he stood for a moment in the doorway, and, beckoning on one of the young men--him of the catechism--they went in together, and the door closed. they remained closeted together for about twenty minutes or half an hour, and then the young man went out; and another young man--he who had procured the contract lines and the whisky--took his place. the interview in this second case, however, was much shorter than the first; and a very few minutes served to despatch the business of the third young man; and then the minister, coming to the doorway, looked first at the old women and then at me, as if mentally determining our respective claims to priority; and, mine at length prevailing--i know not on what occult principle--i was beckoned in. i presented my letter of introduction, which was graciously read; and though the nature of the business did strike me as ludicrously out of keeping with the place, and it did cost me some little trouble to suppress at one time a burst of laughter, that would, of course, have been prodigiously improper in the circumstances, i detailed to him in a few words my little plan, and handed him my copy of verses. he read them aloud with slow deliberation. ode to the ness. child of the lake! whose silvery gleam cheers the rough desert, dark and lone,[ ]-- a brown, deep, sullen, restless stream, with ceaseless speed thou hurriest on. and yet thy banks with flowers are gay; the sun laughs on thy troubled breast; and o'er thy tides the zephyrs play, though nought be thine of quiet rest.[ ] stream of the lake! to him who strays, lonely, thy winding marge along, not fraught with lore of other days, and yet not all unblest in song-- to him thou tell'st of busy men, who madly waste their present day. pursuing hopes, baseless as vain, while life, untasted, glides away. stream of the lake! why hasten on? a boist'rous ocean spreads before, where dash dark tides, and wild winds moan, and foam-wreaths skirt a cheerless shore, nor bending flowers, nor waving fields, nor aught of rest is there for thee; but rest to thee no pleasure yields; then haste and join the stormy sea! stream of the lake! of bloody men, who thirst the guilty fight to try-- who seek for joy in mortal pain, music in misery's thrilling cry-- thou tell'st: peace yields no joy to them, nor harmless pleasure's golden smile; of evil deed the cheerless fame is all the meed that crowns their toil. not such would prove if pleasure shone-- stream of the deep and peaceful lake!-- his course, whom hardship urges on, through cheerless waste and thorny brake. for, ah! each pleasing scene he loves, and peace is all his heart's desire; and, ah! of scenes where pleasure roves, and peace, could gentle minstrel tire? stream of the lake! for thee await the tempests of an angry main; a brighter hope, a happier fate, he boasts, whose present course is pain. yes, even for him may death prepare a home of pleasure, peace, and love; thus blessed by hope, little his care. though rough his present course may prove. the minister paused as he concluded, and looked puzzled. "pretty well, i daresay," he said; "but i do not now read poetry. you, however, use a word that is not english--'thy winding _marge_ along.' marge!--what is marge?" "you will find it in johnson," i said. "ah, but we must not use all the words we find in johnson." "but the poets make frequent use of it." "what poets?" "spenser." "too old--too old; no authority now," said the minister. "but the wartons also use it." "i don't know the wartons." "it occurs also," i iterated, "in one of the most finished sonnets of henry kirke white." "what sonnet?" "that to the river trent. 'once more, o trent! along thy pebbly marge, a pensive invalid, reduced and pale, from the close sick-room newly set at large, woos to his woe-worn cheek the pleasant gale.' it is, in short, one of the common english words of the poetic vocabulary." could a man in quest of patronage, and actually at the time soliciting a favour, possibly contrive to say anything more imprudent? and this, too, to a gentleman so much accustomed to be deferred to when he took up his ground on the _standards_, as sometimes to forget, through the sheer force of habit, that he was not a standard himself! he coloured to the eyes; and his condescending humility, which seemed, i thought, rather too great for the occasion, and was of a kind which my friend mr. stewart never used to exhibit, appeared somewhat ruffled. "i have no acquaintance," he said, "with the editor of the _courier_; we take opposite sides on very important questions; and i cannot recommend your verses to him; but call on mr. ----; he is one of the proprietors; and, with _my compliments_, state your case to him; he will be perhaps able to assist you. meanwhile, i wish you all success." the minister hurried me out, and one of the withered old women was called in. "this," i said to myself, as i stepped into the street, "is the sort of patronage which letters of introduction procure for one. i don't think i'll seek any more of it." meeting on the street, however, with, two cromarty friends, one of whom was just going to call on the gentleman named by the minister, he induced me to accompany him. the other said, as he took his separate way, that having come to visit an old townsman settled in inverness, a man of some influence in the burgh, he would state my case to him; and he was sure he would exert himself to procure me employment. i have already referred to the remark of burns. it is recorded by his brother gilbert, that the poet used often to say, "that he could not well conceive a more mortifying picture of human life, than a man seeking work;" and that the exquisite dirge, "man was made to mourn," owes its existence to the sentiment. the feeling is certainly a very depressing one; and as on most other occasions work rather sought me than i the work, i experienced more of it at this time than at any other period of my life. i of course could hardly expect that people should die off and require epitaphs merely to accommodate me. that demand of employment as a right in all cases and circumstances, which the more extreme "claims-of-labour men" do not scruple to urge, is the result of a sort of indignant reaction on this feeling--a feeling which became poetry in burns and nonsense in the communists; but which i experienced neither as nonsense nor poetry, but simply as a depressing conviction that i was one man too many in the world. the gentleman on whom i now called with my friend was a person both of business habits and literary tastes; but i saw that my poetic scheme rather damaged me in his estimation. the english verse produced at this time in the far north was of a kind ill fitted for the literary market, and usually published, or rather printed--for published it never was--by that teasing subscription scheme which so often robs men of good money, and gives them bad books in exchange; and he seemed to set me down as one of the annoying semi-beggar class;--rather a mistake, i should hope. he, however, obligingly introduced me to a gentleman of literature and science, the secretary of a society of the place, antiquarian and scientific in its character, termed the "northern institution," and the honorary conservator of its museum--an interesting miscellaneous collection which i had previously seen, and in connexion with which i had formed my only other scheme of getting into employment. i wrote that old english hand which has been revived of late by the general rage for the mediæval, but which at that time was one of the lost arts, with much neatness; and could produce imitations of the illuminated manuscripts that preceded our printed books, which even an antiquary would have pronounced respectable. and, addressing the members of the northern institution on the character and tendency of their pursuits, in a somewhat lengthy piece of verse, written in what i least intended to be the manner of dryden, as exemplified in his middle-style poems, such as the _religio laici_, i engrossed it in the old hand, and now called on the secretary, to request that he would present it at the first meeting of the society, which was to be held, i understood, in a few days. the secretary was busy at his desk; but he received me politely, spoke approvingly of my work as an imitation of the old manuscript, and obligingly, charged himself with its delivery at the meeting: and so we parted for the time, not in the least aware that there was a science which dealt with characters greatly more ancient than those of the old manuscripts, and laden with profounder meanings, in which we both took a deep interest, and regarding which we could have exchanged facts and ideas with mutual pleasure and profit. the secretary of the northern institution at this time was mr. george anderson, the well-known geologist, and joint author with his brother of the admirable "guide-book to the highlands," which bears their name. i never heard how my address fared. it would, of course, have been tabled--looked at, i suppose, for a few seconds by a member or two--and then set aside; and it is probably still in the archives of the institution, awaiting the light of future ages, when its simulated antiquity shall have become real. it was not written in a character to be read, nor, i fear, very readable in any character; and so the members of the institution must have remained ignorant of all the wisdom i had found in their pursuits, antiquarian and ethnological. the following forms an average specimen of the production:-- "tis yours to trace each deep-fixed trait that marks the human race; and as the egyptian priests, with mystery fraught, by signs, not words, of sphynx, and horus taught, so, 'mid your stores, by _things_, not books, ye scan the powers, scope, history, of the mind of man. yon chequered wall displays the arms of war of times remote, and nations distant far; alas! the club and brand but serve to show how wide extends the reign of wrong and woe; and tores uncouth, and feathery circlets, tell in human hearts what gewgaw follies dwell. yes! all that man has framed his image bears; and much of hate, and much of pride, appears. "pleasant it is each diverse step to scan, by which the savage first assumes the man; to mark what feelings sway his softening breast, or what strong passion triumphs o'er the rest. narrow of heart, or free, or brave, or base, ev'n in the infant we the man may trace; and from the rude ungainly sires may know each striking trait the polished sons shall show. dependent on what moods assume the reign, science shall smile, or spread her stores in vain: as coward fears, or generous passions sway, shall freedom reign, or heartless slaves obey. "not unto chance must aught of power be given,-- a country's genius is the gift of heaven. what warms the poet's lays with generous fire, to which no toil can reach, no art aspire? who taught the sage, with deepest wisdom fraught, while scarce one pupil grasps the ponderous thought? nay, wherefore ask?--as heaven the mind bestows, a napier calculates and a thomson glows. now turn to where, beneath the city wall, the sun's fierce rays in unbroke splendour fall; vacant and weak, there sits the idiot boy, of pain scarce conscious, scarce alive to joy; a thousand busy sounds around him roar; trade wields the tool, and commerce plies the oar; but, all unheeding of the restless scene, of toil he nothing knows, and nought of gain: the thoughts of common minds were strange to him, ev'n as to such a napier's thoughts would seem. thus, as in men, in peopled states, we find unequal powers, and varied tones of mind: timid or dauntless, high of thought or low, o'erwhelmed with phlegm, or fraught with fire they glow and as the sculptor's art is better shown in parian marble than in porous stone, wreaths fresh or sear'd repay refinement's toil, as genius owns or dulness stamps the soil. where isles of coral stud the southern main, and painted kings and cinctured warriors reign, nations there are who native worth possess,-- whom every art shall court, each science bless: and tribes there are, heavy of heart and slow, on whom no coming age a change shall know." there was, i suspect, a waste of effort in all this planning; but some men seem destined to do things clumsily and ill, at many times the expense which serves to secure success to the more adroit. i despatched my ode to the newspaper, accompanied by a letter of explanation; but it fared as ill as my address to the institution; and a single line in italics in the next number intimated that it was not to appear. and thus both my schemes were, as they ought to be, knocked on the head. i have not schemed any since. strategy is, i fear, not my forte; and it is idle to attempt doing in spite of nature what one has not been born to do well. besides, i began to be seriously dissatisfied with myself: there seemed to be nothing absolutely wrong in a man who wanted honest employment taking this way of showing he was capable of it; but i felt the spirit within rise against it; and so i resolved to ask no more favours of any one, even should poets' corners remain shut against me for ever, or however little institutions, literary or scientific, might favour me with their notice. i strode along the streets, half an inch taller on the strength of the resolution; and straightway, as if to reward me for my magnanimity, an offer of employment came my way unsolicited. i was addressed by the recruiting serjeant of a highland regiment, who asked me if i did not belong to the aird? "no, not to the aird; to cromarty," i replied. "ah, to cromarty--very fine place! but would you not better bid adieu to cromarty, and come along with me? we have a capital grenadier company; and in our regiment a stout steady man is always sure to get on." i thanked him, but declined his invitation; and, with an apology on his part, which was not in the least needed or expected, we parted. though verse and old english failed me, the simple statement made by my cromarty friend to my townsman located in inverness, that i was a good workman, and wanted work, procured me at once the cutting of an inscription, and two little jobs in cromarty besides, which i was to execute on my return home. the inverness job was soon completed; but i had the near prospect of another; and as the little bit of the public that came my way approved of my cutting, i trusted employment would flow in apace. i lodged with a worthy old widow, conscientious and devout, and ever doing her humble work consciously in the eye of the great taskmaster--one of a class of persons not at all so numerous in the world as might be desirable, but sufficiently common to render it rather a marvel that some of our modern masters of fiction should never have chanced--judging from their writings--to come in contact with any of them. she had an only son, a working cabinetmaker, who used occasionally to annoy her by his silly jokes at serious things, and who was courting at this time a sweetheart who had five hundred pounds in the bank--an immensely large sum to a man in his circumstances. he had urged his suit with such apparent success, that the marriage-day was fixed and at hand, and the house which he had engaged as his future residence fully furnished. and it was his prospective brother-in-law who was to be my new employer, so soon as the wedding should leave him leisure enough to furnish epitaphs for two tombstones recently placed in the family burying-ground. the wedding-day arrived; and, to be out of the way of the bustle and the pageant, i retired to the house of a neighbour, a carpenter, whom i had obliged by a few lessons in practical geometry and architectural drawing. the carpenter was at the wedding; and, with the whole house to myself, i was engaged in writing, when up flew the door, and in rushed my pupil the carpenter. "what has happened?" i asked. "happened!" said the carpenter,--"happened!! the bride's away with another man!! the bridegroom has taken to his bed, and raves like a madman; and his poor old mother--good honest woman--is crying like a child. do come and see what can be done." i accompanied him to my landlady's, where i found the bridegroom in a paroxysm of mingled grief and rage, congratulating himself on his escape, and bemoaning his unhappy disappointment, by turns. he lay athwart the bed, which he told me in the morning he had quitted for the last time; but as i entered, he half rose, and, seizing on a pair of new shoes which had been prepared for the bride, and lay on a table beside him, he hurled them against the wall, first the one and then the other, until they came rebounding back across the room; and then, with an exclamation that need not be repeated, he dashed himself down again. i did my best to comfort his poor mother, who seemed to feel very keenly the slight done to her son, and to anticipate with dread the scandal and gossip of which it would render her humble household the subject. she seemed sensible, however, that he had made an escape, and at once acquiesced in my suggestion, that all that should now be done would be to get every expense her son had been at in his preparations for housekeeping and the wedding transferred to the shoulders of the other party. and such an arrangement could, i thought, be easily effected through the bride's brother, who seemed to be a reasonable man, and who would be aware also that a suit at law could be instituted in the case against his sister; though in any such suit i held it might be best for both parties not to engage. and at the old woman's request, i set out with the carpenter to wait on the bride's brother, in order to see whether he was not prepared for some such arrangement as i suggested, and, besides, able to furnish us with some explanation of the extraordinary step taken by the bride. we were overtaken, as we passed along the street, by a person who was, he said, in search of us, and who now requested us to accompany him; and, threading our way, under his guidance, through a few narrow lanes that traverse the assemblage of houses on the west bank of the ness, we stopped at the door of an obscure alehouse. this, said our conductor, we have found to be the retreat of the bride. he ushered us into a room occupied by some eight or ten persons, drawn up on the opposite sides, with a blank space between. on the one side sat the bride, a high-coloured, buxom young girl, serene and erect as britannia on the halfpennies, and guarded by two stout fellows, masons or slaters apparently, in their working dresses. they looked hard at the carpenter and me as we entered, of course regarding us as the assailants against whom they would have to maintain their prize. on the other side sat a group of the bride's relatives--among the rest her brother--silent, and all apparently very much grieved; while in the space between them there stumped up and down a lame, sallow-complexioned oddity, in shabby black, who seemed to be making a set oration, to which no one replied, about the sacred claims of love, and the cruelty of interfering with the affections of young people. neither the carpenter nor myself felt any inclination to debate with the orator, or fight with the guards, or yet to interfere with the affections of the young lady; and so, calling out the brother into another room, and expressing our regret at what had happened, we stated our case, and found him, as we had expected, very reasonable. we could not, however, treat for the absent bridegroom, nor could he engage for his sister; and so we had to part without coming to any agreement. there were points about the case which at first i could not understand. my jilted acquaintance the cabinetmaker had not only enjoyed the countenance of all his mistress's relatives, but he had been also as well received by herself as lovers usually are: she had written him kind letters, and accepted of his presents; and then, just as her friends were sitting down to the marriage breakfast, she had eloped with another man. the other man, however--a handsome fellow, but great scamp--had a prior claim to her regards: he had been the lover of her choice, though detested by her brother and all her friends, who were sufficiently well acquainted with his character to know that he would land her in ruin; and during his absence in the country, where he was working as a slater, they had lent their influence and countenance to my acquaintance the cabinetmaker, in order to get her married to a comparatively safe man, out of the slater's reach. and, not very strong of will, she had acquiesced in the arrangement. on the eve of the marriage, however, the slater had come into town; and, exchanging clothes with an acquaintance a highland soldier, he had walked unsuspected opposite her door, until, finding an opportunity of conversing with her on the morning of the wedding-day, he had represented her new lover as a silly, ill-shaped fellow, who had just head enough to be mercenary, and himself as one of the most devoted and disconsolate of lovers. and, his soft tongue and fine leg gaining the day, she had left the marriage guests to enjoy their tea and toast without her, and set off with him to the change-house. ultimately the affair ended ill for all parties. i lost my job, for i saw no more of the bride's brother; the wrong-headed cabinetmaker, contrary to the advice of his mother and her lodger, entered into a law-suit, in which he got small damages and much vexation; and the slater and his mistress broke out into such a course of dissipation after becoming man and wife, that they and the five hundred pounds came to an end almost together. shortly after, my landlady and her son quitted the country for the united states. so favourably had the poor woman impressed me as one of the truly excellent, that i took a journey from cromarty to inverness--a distance of nineteen miles--to bid her farewell; but i found, on my arrival, her house shut up, and learned that she had left the place for some sailing port on the west coast two days before. she was a humble washerwoman; but i am convinced that in the other world, which she must have entered long ere now, she ranks considerably higher! i waited on in inverness, in the hope that, according to burns, "my brothers of the earth would give me leave to toil;" but the hope was a vain one, as i succeeded in procuring no second job. there was no lack, however, of the sort of employment which i could cut out for myself; but the remuneration--only now in the process of being realized, and that very slowly--had to be deferred to a distant day. i had to give more than twelve years' _credit_ to the pursuits that engaged me: and as my capital was small, it was rather a trying matter to be "kept so long out of my wages." there is a wonderful group of what are now termed _osars_, in the immediate neighbourhood of inverness--a group to which that queen of scottish tomhans, the picturesque tomnahuirich, belongs, and to the examination of which i devoted several days. but i learned only to state the difficulty which they form--not to solve it; and now that agassiz has promulgated his glacial theory, and that traces of the great ice agencies have been detected all over scotland, the mystery of the _osars_ remains a mystery still. i succeeded, however, in determining at this time, that they belong to a later period than the boulder clay, which i found underlying the great gravel formation of which they form a part, in a section near loch ness that had been laid open shortly before, in excavating for the great caledonian canal. and as all, or almost all, the shells of the boulder clay are of species that still live, we may infer that the mysterious osars were formed not very long ere the introduction upon our planet of the inquisitive little creature that has been puzzling himself--hitherto at least with no satisfactory result--in attempting to account for their origin. i examined, too, with some care, the old coast-line, so well developed in this neighbourhood as to form one of the features of its striking scenery, and which must be regarded as the geological memorial and representative of those latter ages of the world in which the human epoch impinged on the old pre-adamite periods. the magistrates of the place were engaged at the time in doing their duty, like sensible men, as they were, in what i could not help thinking a somewhat barbarous instance. the neat, well proportioned, very uninteresting jail-spire of the burgh, about which, in its integrity, no one cares anything, had been shaken by an earthquake, which took place in the year , into one of the greatest curiosities in the kingdom. the earthquake, which, for a scotch one, had been unprecedentedly severe, especially in the line of the great caledonian valley, had, by a strange vorticose motion, twisted round the spire, so that, at the transverse line of displacement, the _panes_ and corners of the octagonal broach which its top formed overshot their proper positions fully seven inches. the corners were carried into nearly the middle of the _panes_, as if some gigantic hand, in attempting to twirl round the building by the spire, as one twirls round a spinning top by the stalk or bole, had, from some failure in the coherency of the masonry, succeeded in turning round only the part of which it had laid hold. sir charles lyell figures, in his "principles," similar shifts in stones of two obelisks in a calabrian convent, and subjoins the ingenious suggestion on the subject of messrs. darwin and mallet. and here was there a scotch example of the same sort of mysterious phenomena, not less curious than the calabrian one, and certainly unique in its character _as scotch_, which, though the injured building had already stood twelve years in its displaced condition, and might stand for as many more as the hanging tower of pisa, the magistrates were laboriously effacing at the expense of the burgh. they were completely successful too; and the jail spire was duly restored to its state of original insignificance, as a fifth-rate piece of ornamental masonry. but how very absurd, save, mayhap, here and there to a geologist, must not these remarks appear! but my criticisms on the magistracy, however foolish, were silent criticisms, and did harm to no one. about the time, however, in which i was indulging in them, i imprudently exposed myself, by one of those impulsive acts of which men repent at their leisure, to criticisms not silent, and of a kind that occasionally _do_ harm. i had been piqued by the rejection of my verses on the ness. true, i had no high opinion of their merit, deeming them little more than equal to the average verses of provincial prints; but then i had intimated my scheme of getting them printed to a few cromarty friends, and was now weak enough to be annoyed at the thought that my townsfolk would regard me as an incompetent blockhead, who could not write rhymes good enough for a newspaper. and so i rashly determined on appealing to the public in a small volume. had i known as much as in an after period about newspaper affairs, and the mode in which copies of verses are often dealt with by editors and their assistants--fatigued with nonsense, and at once hopeless of finding grain in the enormous heaps of chaff submitted to them, and too much occupied to seek for it, even should they believe in its occurrence in the form of single seeds sparsely scattered--i would have thought less of the matter. as the case was, however, i hastily collected from among my piles of manuscripts, some fifteen or twenty pieces in verse, written chiefly during the preceding six years, and put them into the hands of the printer of the _inverness courier_. it would have been a greatly wiser act, as i soon came to see, had i put them into the fire instead; but my choice of a printing-office secured to me at least one advantage--it brought me acquainted with one of the ablest and most accomplished of scotch editors--the gentleman who now owns and still conducts the _courier_; and, besides, having once crossed the rubicon, i felt all my native obstinacy stirred up to make good a position for myself, despite of failures and reverses on the further side. it is an advantage in some cases to be committed. the clear large type of the _courier_ office did, however, show me many a blemish in my verse that had escaped me before, and broke off associations which--curiously linked with the manuscripts--had given to the stanzas and passages which they contained charms of tone and colour not their own. i began to find, too, that my humble accomplishment of verse was too narrow to contain my thinking;--the thinking ability had been growing, but not the ability of poetic expression; nay, much of the thinking seemed to be of a kind not suited for poetic purposes at all;--and though it was of course far better that i should come to know this in time, than that, like some, even superior men, i should persist in wasting, in inefficient verse, the hours in which vigorous prose might be produced, it was at least quite mortifying enough to make the discovery with half a volume of metre committed to type, and in the hands of the printer. resolving, however, that my humble name should not appear in the title-page, i went on with my volume. my new friend the editor kindly inserted, from time to time, copies of its verses in the columns of his paper, and strove to excite some degree of interest and expectation regarding it; but my recent discovery had thoroughly sobered me, and i awaited the publication of my volume not much elated by the honour done me, and as little sanguine respecting its ultimate success as well might be. and ere i quitted inverness, a sad bereavement, which greatly narrowed the circle of my best-loved friends, threw very much into the background all my thoughts regarding it. on quitting cromarty, i had left my uncle james labouring under an attack of rheumatic fever; but though he had just entered his grand climacteric, he was still a vigorous and active man, and i could not doubt that he had strength of constitution enough to throw it off. he had failed to rally, however; and after returning one evening from a long exploratory walk, i found in my lodgings a note awaiting me, intimating his death. the blow fell with stunning effect. ever since the death of my father, my two uncles had faithfully occupied his place; and james, of a franker and less reserved temper than alexander, and more tolerant of my boyish follies, had, though i sincerely loved the other, laid stronger hold on my affections. he was of a genial disposition, too, that always remained sanguine in the cast of its hopes and anticipations; and he had unwittingly flattered my vanity by taking me pretty much at my own estimate--overweeningly high, of course, like that of almost all young men, but mayhap necessary, in the character of a force, to make headway in the face of obstruction and difficulty. uncle james, like _le balafré_ in the novel, would have "ventured his nephew against the wight wallace." i immediately set out for cromarty; and, curious as it may seem, found grief so companionable, that the four hours which i spent by the way seemed hardly equal to one. i retained, however, only a confused recollection of my journey, remembering little more than that, when passing at midnight along the dreary maolbuie, i saw the moon in her wane, rising red and lightless out of the distant sea; and that, lying, as it were, prostrate on the horizon, she reminded me of some o'ermatched wrestler thrown helplessly on the ground. on reaching home, i found my mother, late as the hour was, still up, and engaged in making a dead-dress for the body. "there is a letter from the south, with a black seal, awaiting you," she said; "i fear you have also lost your friend william ross." i opened the letter, and found her surmise too well founded. it was a farewell letter, written in feeble characters, but in no feeble spirit; and a brief postscript, added by a comrade, intimated the death of the writer. "this," wrote the dying man, with a hand fast forgetting its cunning, "is, to all human probability, my last letter; but the thought gives me little trouble; for my hope of salvation is in the blood of jesus. farewell, my sincerest friend!" there is a provision through which nature sets limits to both physical and mental suffering. a man partially stunned by a violent blow is sometimes conscious that it is followed by other blows, rather from seeing than from feeling them; his capacity of suffering has been exhausted by the first; and the others that fall upon him, though they may injure, fail to pain. and so also it is with strokes that fall on the affections. in other circumstances, i would have grieved for the death of my friend, but my mind was already occupied to the full by the death of my uncle; and, though i _saw_ the new stroke, several days elapsed ere _i could feel_ it. my friend, after half a lifetime of decline, had sunk suddenly. a comrade who lived with him--a stout, florid lad--had been seized by the same insidious malady as his own, about a twelvemonth before; and, previously unacquainted with sickness, in him the progress of the disease had been rapid, and his sufferings were so great, that he was incapacitated for work several months ere his death. but my poor friend, though sinking at the time, wrought for both: he was able to prosecute his employments--which, according to bacon, "required rather the finger than the arm"--in even the latter stages of his complaint; and after supporting and tending his dying comrade till he sank, he himself suddenly broke down and died. and thus perished unknown, and in the prime of his days, a man of sterling principle and fine genius. i found employment enough for the few weeks which still remained of the working season of this year, in hewing a tombstone for my uncle james, on which i inscribed an epitaph of a few lines, that had the merit of being true. it characterized the deceased--"james wright"--as "an honest, warm-hearted man, who had the happiness of living without reproach, and of dying without fear." footnotes: [ ] loch ness. [ ] this portrait of the ness is, i fear, scarce true to the ordinary character of the river. i had visited it during the previous winter, and walked a few miles along its sides, when the tract of country through which it flows lay bleached and verdureless, and steeped in the soaking rain of weeks, and the stream itself, big in flood, roared from bank to brae in its shallower reaches, or boiled sullen and turbid in many a circling eddy in its darker pools. and my description somewhat incongruously unites a sunlit summer landscape, rich in flower and foliage, with the brown wintry river. chapter xx. "this while my notion's ta'en a sklent, to try my fate in guid black prent; but still the mair i'm that way bent, something cries, hoolie! i red you, honest man, tak tent; ye'll shaw your folly."--burns. my volume of verse passed but slowly through the press; and as i had begun to look rather ruefully forward to its appearance, there was no anxiety evinced on my part to urge it on. at length, however, all the pieces were thrown into type; and i followed them up by a tail-piece in prose, formed somewhat on the model of the preface of pope--for i was a great admirer, at the time, of the english written by the "wits of queen anne"--in which i gave serious expression to the suspicion that, as a writer of verse, i had mistaken my vocation. "it is more than possible," i said, "that i have completely failed in poetry. it may appear that, while grasping at originality of description and sentiment, and striving to attain propriety of expression, i have only been depicting common images, and embodying obvious thoughts, and this, too, in inelegant language. yet even in this case, though disappointed, i shall not be without my sources of comfort. the pleasure which i enjoy in composing verses is quite independent of other men's opinions of them; and i expect to feel as happy as ever in this amusement, even though assured that others could find no pleasure in reading what i had found so much in writing. it is no small solace to reflect, that the fable of the dog and shadow cannot apply to me, since my predilection for poetry has not prevented me from acquiring the skill of at least the common mechanic. i am not more ignorant of masonry and architecture than many professors of these arts who never measured a stanza. there is also some satisfaction in reflecting that, unlike some would-be satirists i have not assailed private character; and that, though men may deride me as an unskilful poet, they cannot justly detest me as a bad or ill-natured man. nay, i shall possibly have the pleasure of repaying those who may be merry at my expense, in their own coin. an ill-conditioned critic is always a more pitiable sort of person than an unsuccessful versifier; and the desire of showing one's own discernment at the expense of one's neighbour, a greatly worse thing than the simple wish, however divorced from the ability, of affording him harmless pleasure. further, it would, i think, not be difficult to show that my mistake in supposing myself a poet is not a whit more ridiculous, and infinitely less mischievous, than many of those into which myriads of my fellow-men are falling every day. i have seen the vicious attempting to teach morals, and the weak to unfold mysteries. i have seen men set up for freethinkers who were born not to think at all. to conclude, there will surely be cause for self-gratulation in reflecting that, by becoming an author, i have only lost a few pounds, not gained the reputation of being a mean fellow, who had teased all his acquaintance until they had subscribed for a worthless book; and that the severest remark of the severest critic can only be, 'a certain anonymous rhymer is no poet.'" as, notwithstanding the blank in the title-page, the authorship of my volume would be known in cromarty and its neighbourhood, i set myself to see whether i could not, meanwhile, prepare for the press something better suited to make an impression in my favour. in tossing the bar or throwing the stone, the competitor who begins with a rather indifferent cast is never very unfavourably judged if he immediately mend it by giving a better; and i resolved on mending my cast, if i could, by writing for the _inverness courier_--which was now open to me, through the kindness of the editor--a series of carefully prepared letters on some popular subject. in the days of goldsmith, the herring-fishing employed, as he tells us in one of his essays, "all grub street." in the north of scotland this fishery was a popular theme little more than twenty years ago. the welfare of whole communities depended in no slight degree on its success: it formed the basis of many a calculation, and the subject of many an investment; and it was all the more suitable for my purpose from the circumstance that there was no grub street in that part of the world to employ itself about it. it was, in at least all its better aspects, a fresh subject; and i deemed myself more thoroughly acquainted with it than at least most of the men who were skilful enough, as _littérateurs_, to communicate their knowledge in writing. i knew the peculiarities of fishermen as a class, and the effects of this special branch of their profession on their character: i had seen them pursuing their employments amid the sublime of nature, and had occasionally taken a share in their work; and, further, i was acquainted with not a few antique traditions of the fishermen of other ages, in which, as in the narratives of most seafaring men, there mingled with a certain amount of real incident, curious snatches of the supernatural. in short, the subject was one on which, as i knew a good deal regarding it that was not generally known, i was in some degree qualified to write; and so i occupied my leisure in casting my facts respecting it into a series of letters, of which the first appeared in the _courier_ a fortnight after my volume of verse was laid on the tables of the north country booksellers. i had first gone out to sea to assist in catching herrings about ten years before; and i now described, in one of my letters, as truthfully as i could, those features of the scene to which i had been introduced on that occasion, which had struck me as novel and peculiar. and what had been strange to me proved equally so, i found, to the readers of the _courier_. my letters attracted attention, and were republished in my behalf by the proprietors of the paper, "in consequence," said my friend the editor, in a note which he kindly attached to the pamphlet which they formed, "of the interest they had excited in the northern counties."[ ] their modicum of success, lowly as was their subject, compared with that of some of my more ambitious verses, taught me my proper course. let it be my business, i said, to know what is not generally known;--let me qualify myself to stand as an interpreter between nature and the public: while i strive to narrate as pleasingly and describe as vividly as i can, let truth, not fiction, be my walk; and if i succeed in uniting the novel to the true, in provinces of more general interest than the very humble one in which i have now partially succeeded, i shall succeed also in establishing myself in a position which, if not lofty, will yield me at least more solid footing than that to which i might attain as a mere _littérateur_ who, mayhap, pleased for a little, but added nothing to the general fund. the resolution was, i think, a good one; would that it had been better kept! the following extracts may serve to show that, humble as my new subject may be deemed, it gave considerable scope for description of a kind not often associated with herrings, even when they employed all grub street:-- "as the night gradually darkened, the sky assumed a dead and leaden hue: the sea, roughened by the rising breeze, reflected its deeper hues with an intensity approaching to black, and seemed a dark uneven pavement, that absorbed every ray of the remaining light. a calm silvery patch, some fifteen or twenty yards in extent, came moving slowly through the black. it seemed merely a patch of water coated with oil; but, obedient to some other moving power than that of either tide or wind, it sailed aslant our line of buoys, a stone-cast from our bows--lengthened itself along the line to thrice its former extent--paused as if for a moment--and then three of the buoys, after erecting themselves on their narrower base, with a sudden jerk slowly sank. 'one--two--three buoys!' exclaimed one of the fishermen, reckoning them as they disappeared;--'_there_ are ten barrels for us secure.' a few moments were suffered to elapse: and then, unfixing the haulser from the stem, and bringing it aft to the stern, we commenced hauling. the nets approached the gunwale. the first three appeared, from the phosphoric light of the water, as if bursting into flames of a pale green colour. here and there a herring glittered bright in the meshes, or went darting away through the pitchy darkness, visible for a moment by its own light. the fourth net was brighter than any of the others, and glittered through the waves while it was yet several fathoms away: the pale green seemed as if mingled with broken sheets of snow, that--flickering amid the mass of light--appeared, with every tug given by the fishermen, to shift, dissipate, and again form; and there streamed from it into the surrounding gloom myriads of green rays, an instant seen and then lost--the retreating fish that had avoided the meshes, but had lingered, until disturbed, beside their entangled companions. it contained a considerable body of herrings. as we raised them over the gunwale, they felt warm to the hand, for in the middle of a large shoal even the temperature of the water is raised--a fact well known to every herring fisherman; and in shaking them out of the meshes, the ear became sensible of a shrill, chirping sound, like that of the mouse, but much fainter--a ceaseless cheep, cheep, cheep, occasioned apparently--for no true fish is furnished with organs of sound--by a sudden escape from the air-bladder. the shoal, a small one, had spread over only three of the nets--the three whose buoys had so suddenly disappeared; and most of the others had but their mere sprinkling of fish, some dozen or two in a net; but so thickly had they lain in the fortunate three, that the entire haul consisted of rather more than twelve barrels. * * * * * we started up about midnight, and saw an open sea, as before; but the scene had considerably changed since we had lain down. the breeze had died into a calm; the heavens, no longer dark and grey, were glowing with stars; and the sea, from the smoothness of the surface, appeared a second sky, as bright and starry as the other; with this difference, however, that all its stars seemed to be comets! the slightly tremulous motion of the surface elongated the reflected images, and gave to each its tail. there was no visible line of division at the horizon. where the hills rose high along the coast, and appeared as if doubled by their undulating strip of shadow, what might be deemed a dense hank of cloud lay sleeping in the heavens, just where the upper and nether firmaments met; but its presence rendered the illusion none the less complete: the outline of the boat lay dark around us, like the fragment of some broken planet suspended in middle space, far from the earth and every star; and all around we saw extended the complete sphere--unhidden above from orion to the pole, and visible beneath from the pole to orion. certainly sublime scenery possesses in itself no virtue potent enough to develop the faculties, or the mind of the fisherman would not have so long lain asleep. there is no profession whose recollections should rise into purer poetry than his; but if the mirror bear not its previous amalgam of taste and genius, what does it matter though the scene which sheds upon it its many-coloured light should be rich in grandeur and beauty? there is no corresponding image produced: the susceptibility of reflecting the landscape is never imparted by the landscape itself, whether to the mind or to the glass. there is no class of recollections more illusory than those which associate--as if they existed in the relation of cause and effect--some piece of striking scenery with some sudden development of the intellect or imagination. the eyes open, and there is an external beauty seen; but it is not the external beauty that has opened the eyes. * * * * * "it was still a dead calm--calm to blackness; when, in about an hour after sunrise, what seemed light fitful airs began to play on the surface, imparting to it, in irregular patches, a tint of grey. first one patch would form, then a second beside it, then a third, and then for miles around, the surface, else so silvery, would seem frosted over with grey: the apparent breeze appeared as if propagating itself from one central point. in a few seconds after, all would be calm as at first; and then from some other centre the patches of grey would again form and widen, till the whole firth seemed covered by them. a peculiar poppling noise, as if a thunder-shower was beating the surface with its multitudinous drops, rose around our boat; the water seemed sprinkled with an infinity of points of silver, that for an instant glittered to the sun, and then resigned their places to other quick glancing points, that in turn were succeeded by yet others. the herrings by millions, and thousands of millions, were at play around us, leaping a few inches into the air, and then falling and disappearing, to rise and leap again. shoal rose beyond shoal, till the whole bank of gulliam seemed beaten into foam, and the low poppling sounds were multiplied into a roar, like that of the wind through some tall wood, that might be heard in the calm for miles. and again, the shoals extending around us seemed to cover, for hundreds of square miles, the vast moray firth. but though they played beside our buoys by thousands, not a herring swam so low as the upper baulk of our drift. one of the fishermen took up a stone, and, flinging it right over our second buoy into the middle of the shoal, the fish disappeared from the surface for several fathoms around. 'ah, there they go,' he exclaimed, 'if they go but low enough. four years ago i startled thirty barrels of light fish into my drift just by throwing a stone among them.' i know not what effect the stone might have had on this occasion; but on hauling our nets for the third and last time, we found we had captured about eight barrels of fish; and then hoisting sail--for a light breeze from the east had sprung up--we made for the shore with a cargo of twenty barrels." meanwhile the newspaper critics of the south were giving expression to all sorts of judgments on my verses. it was intimated in the title of the volume that they had been "written in the leisure hours of a journeyman mason;" and the intimation seemed to furnish most of my reviewers with the proper cue for dealing with them. "the time has gone by," said one, "when a literary mechanic used to be regarded as a phenomenon: were a second burns to spring up now, he would not be entitled to so much praise as the first." "it is our duty to tell this writer," said another, "that he will make more in a week by his trowel than in half a century by his pen." "we are glad to understand," said a third--very judiciously, however--"that our author has the good sense to rely more on his chisel than on the muses." the lessons taught were of a sufficiently varied, but, on the whole, rather contradictory character. by one writer i was told that i was a dull, correct fellow, who had written a book in which there was nothing amusing and nothing absurd. another, however, cheered my forlorn spirits by assuring me that i was a "man of genius, whose poems, with much that was faulty, contained also much that was interesting." a third was sure i had "no chance whatever of being known beyond the limits of my native place," and that my "book exhibited none, or next to none, of those indications which sanction the expectation of better things to come;" while a fourth, of a more sanguine vein, found in my work the evidence of "gifts of nature, which the stimulus of encouragement, and the tempering lights of experience, might hereafter develop, and direct to the achievement of something truly wonderful." there were two names in particular that my little volume used to suggest to the newspaper reviewers. the tam o'shanter and souter johnnie of the ingenious thorn were in course of being exhibited at the time; and it was known that thorn had wrought as a journeyman mason: and there was a rather slim poet called sillery, the author of several forgotten volumes of verse, one of which had issued from the press contemporaneously with mine, who, as he had a little money, and was said to treat his literary friends very luxuriously, was praised beyond measure by the newspaper critics, especially by those of the scottish capital. and thom as a mason, and sillery as a poet, were placed repeatedly before me. one critic, who was sure i would never come to anything, magnanimously remarked, however, that as he bore me no ill will, he would be glad to find himself mistaken; nay, that it would give him "unfeigned pleasure to learn i had attained to the well-merited fame of even mr. thom himself." and another, after deprecating the undue severity so often shown by the bred writer to the working man, and asserting that the "journeyman mason" was in this instance, notwithstanding his treatment, a man of fair parts, ended by remarking, that it was of course not even every man of merit who could expect to attain to the "high poetic eminence and celebrity of a charles doyne sillery." all this, however, was criticism at a distance, and disturbed me but little when engaged in toiling in the churchyard, or in enjoying my quiet evening walks. but it became more formidable when, on one occasion, it came to beard me in my den. the place was visited by an itinerant lecturer on elocution--one walsh, who, as his art was not in great request among the quiet ladies and busy gentlemen of cromarty, failed to draw houses; till at length there appeared one morning, placarded on post and pillar, an intimation to the effect, that mr. walsh would that evening deliver an elaborate criticism on the lately-published volume of "poems written in the leisure hours of a journeyman mason," and select from it a portion of his evening readings. the intimation drew a good house; and, curious to know what was awaiting me, i paid my shilling, with the others, and got into a corner. first in the entertainment there came a wearisome dissertation on harmonic inflections, double emphasis, the echoing words, and the monotones. but, to borrow from meg dods, "oh, what a style of language!" the elocutionist, evidently an untaught and grossly ignorant man, had not an idea of composition. syntax, grammar, and good sense, were set at nought in every sentence; but then, on the other hand, the inflections were carefully maintained, and went rising and falling over the nonsense beneath, like the wave of some shallow bay over a bottom of mud and comminuted sea-weed. after the dissertation we were gratified by a few recitations. "lord ullin's daughter," the "razor seller," and "my name is norval," were given in great force. and then came the critique. "ladies and gentlemen," said the reviewer, "we cannot expect much from a journeyman mason in the poetry line. right poetry needs teaching. no man can be a proper poet unless he be an elocutionist; for, unless he be an elocutionist, how can he make his verses emphatic in the right places, or manage the harmonic inflexes, or deal with the rhetorical pauses? and now, ladies and gentlemen, i'll show you, from various passages in this book, that the untaught journeyman mason who made it never took lessons in elocution. i'll first read you a passage from a piece of verse called the 'death of gardiner'--the person meant being the late colonel gardiner, i suppose. the beginning of the piece is about the running away of johnnie cope's men:"-- * * * * * "yet in that craven, dread-struck host, one val'rous heart beat keen and high; in that dark hour of shameful flight, one stayed behind to die! deep gash'd by many a felon blow, he sleeps where fought the vanquish'd van-- of silver'd locks and furrow'd brow, a venerable man. e'en when his thousand warriors fled-- their low-born valour quail'd and gone-- he--the meek leader of that band-- remained, and fought alone. he stood; fierce foemen throng'd around; the hollow death-groans of despair. the clashing sword, the cleaving axe, the murd'rous dirk were there. valour more stark, or hands more strong, ne'er urged the brand or launch'd the spear but what were these to that old man! god was his only fear. he stood where adverse thousands throng'd. and long that warrior fought and well;-- bravely he fought, firmly he stood, till where he stood he fell. he fell--he breathed one patriot prayer. then to his god his soul resign'd: not leaving of earth's many sons a better man behind. his valour, his high scorn of death, to fame's proud meed no impulse owed; his was a pure, unsullied zeal, for britain and for god. he fell--he died;--the savage foe trod careless o'er the noble clay; yet not in vain that champion fought, in that disastrous fray. on bigot creeds and felon swords partial success may fondly smile, till bleeds the patriot's honest heart, and flames the martyr's pile. yet not in vain the patriot bleeds; yet not in vain the martyr dies; from ashes mute, and voiceless blood, what stirring memories rise! the scoffer owns the bigot's creed, though keen the secret gibe may be; the sceptic seeks the tyrant's dome. and bends the ready knee. but oh! in dark oppression's day. when flares the torch, when flames the sword. who are the brave in freedom's cause? the men who fear the lord."[ ] "now, ladies and gentlemen," continued the critic, "this is very bad poetry. i defy any elocutionist to read it satisfactorily with the inflexes. and, besides, only see how full it is of tautology. let us take but one of the verses:--'he fell--he died!' to fall in battle means, as we all know, to die in battle;--to die in battle is exactly the same thing as to fall in battle. to say 'he fell--he died,' is therefore just tantamount to saying that he fell, he fell, or that he died, he died, and is bad poetry, and tautology. and this is one of the effects of ignorance, and a want of right education." here, however, a low grumbling sound, gradually shaping itself into words, interrupted the lecturer. there was a worthy old captain among the audience, who had not given himself very much to the study of elocution or the _belles-lettres_; he had been too much occupied in his younger days in dealing at close quarters with the french under howe and nelson, to leave him much time for the niceties of recitation or criticism. but the brave old man bore a genial, generous heart; and the strictures of the elocutionist, emitted, as all saw, in the presence of the assailed author, jarred on his feelings. "it was not gentlemanly," he said, "to attack in that way an inoffensive man: it was wrong. the poems were, he was told, very good poems. he knew good judges that thought so; and unprovoked remarks on them, such as those of the lecturer, ought not to be permitted." the lecturer replied, and in glibness and fluency would have been greatly an overmatch for the worthy captain; but a storm of hisses backed the old veteran, and the critic gave way. as his remarks were, he said, not to the taste of the audience--though he was taking only the ordinary critical liberty--he would go on to the readings. and with a few extracts, read without note or comment, the entertainment of the evening concluded. there was nothing very formidable in the critique of walsh; but, having no great powers of face, i felt it rather unpleasant to be stared at in my quiet corner by every one in the room, and looked, i daresay, very much put out; and the sympathy and condolence of such of my townsfolk as comforted me in the state of supposed annihilation and nothingness to which his criticism had reduced me, were just a little annoying. poor walsh, however, had he but known what threatened him, would have been considerably less at ease than his victim. the cousin walter introduced to the reader in an early chapter as the companion of one of my highland journeys, had grown up into a handsome and very powerful young man. one might have guessed his stature at about five feet ten or so, but it in reality somewhat exceeded six feet: he had amazing length and strength of arm; and such was his structure of bone, that, as he tucked up his sleeve to send a bowl along the town links, or to fling the hammer or throw the stone, the knobbed protuberances of the wrist, with the sinews rising sharp over them, reminded one rather of the framework of a horse's leg, than of that of a human arm. and walter, though a fine, sweet-tempered fellow, had shown, oftener than once or twice, that he could make a very formidable use of his great strength. some of the later instances had been rather interesting in their kind. there had been a large dutch transport, laden with troops, forced by stress of weather into the bay shortly before, and a handsome young soldier of the party--a native of northern germany, named wolf--had, i know not how, scraped acquaintance with walter. wolf, who, like many of his country-folk, was a great reader, and intimately acquainted, through german translations, with the waverley novels, had taken all his ideas of scotland and its people from the descriptions of scott; and in walter, as handsome as he was robust, he found the _beau-idéal_ of a scottish hero. he was a man cast in exactly the model of the harry bertrams, halbert glendinnings, and quentin durwards of the novelist. for the short time the vessel lay in the harbour, wolf and walter were inseparable. walter knew a little, mainly at second hand, through his cousin, about the heroes of scott; and wolf delighted to converse with him in his broken english about balfour of burley, rob roy, and vich ian vohr: and ever and anon would he urge him to exhibit before him some feat of strength or agility--a call to which walter was never slow to respond. there was a serjeant among the troops--a dutchman, regarded as their strongest man, who used to pride himself much on his prowess; and who, on hearing wolf's description of walter, expressed a wish to be introduced to him. wolf soon found the means of gratifying the serjeant. the strong dutchman stretched out his hand, and, on getting hold of walter's, grasped it very hard. walter saw his design, and returned the grasp with such overmastering firmness, that the hand became powerless within his. "ah!" exclaimed the dutchman, in his broken english, shaking his fingers, and blowing upon them, "me no try squeeze hand with you again; you very _very_ strong man." wolf for a minute after stood laughing and clapping his hands, as if the victory were his, not walter's. when at length the day arrived on which the transport was to sail, the two friends seemed as unwilling to part as if they had been attached for years. walter presented wolf with a favourite snuff-box; wolf gave walter his fine german pipe. before i had risen on the morning of the day succeeding that in which i had been demolished by the elocutionist, cousin walter made his way to my bedside, with a storm on his brow dark as midnight. "is it true, hugh," he inquired, "that the lecturer walsh ridiculed you and your poems in the council house last night?" "oh, and what of that?" i said; "who cares anything for the ridicule of a blockhead?" "ay," said walter, "that's always your way; but _i_ care for it! had i been there last night, i would have sent the puppy through the window, to criticize among the nettles in the yard. but there's no time lost: i shall wait on him when it grows dark this evening, and give him a lesson in good manners." "not for your life, walter!" i exclaimed. "oh," said walter, "i shall give walsh all manner of fair play." "fair play!" i rejoined; "you cannot give walsh fair play; you are an overmatch for five walshes. if you meddle with him at all, you will kill the poor slim man at a blow, and then not only will you be apprehended for manslaughter--mayhap for murder--but it will also be said that i was mean enough to set you on to do what i had not courage enough to do myself. you _must_ give up all thoughts of meddling with walsh." in short, i at length partially succeeded in convincing walter that he might do me a great mischief by assaulting my critic; but so little confident was i of his seeing the matter in its proper light, that when the lecturer, unable to get audiences, quitted the place, and walter had no longer opportunity of avenging my cause, i felt a load of anxiety taken from off my mind. there reached cromarty shortly after, a criticism that differed considerably from that of walsh, and restored the shaken confidence of some of my acquaintance. the other criticisms which had appeared in newspapers, critical journals, and literary gazettes, had been evidently the work of small men; and, feeble and commonplace in their style and thinking, they carried with them no weight--for who cares anything for the judgment, on one's writings, of men who themselves cannot write? but here, at length, was there a critique eloquently and powerfully written. it was, however, at least as extravagant in its praise as the others in their censure. the friendly critic knew nothing of the author he commended; but he had, i suppose, first seen the deprecatory criticisms, and then glanced his eye over the volume which they condemned; and finding it considerably better than it was said to be, he had rushed into generous praise, and described it as really a great deal better than it was. after an extravagantly high estimate of the powers of its author, he went on to say--"nor, in making these observations, do we speak relatively, or desire to be understood as merely saying that the poems before us are remarkable productions to emanate from a 'journeyman mason.' that this is indeed the case, no one who reads them can doubt; but in characterizing the poetical talent they display, our observations are meant to be quite absolute; and we aver, without fear of contradiction, that the pieces contained in the humble volume before us bear the stamp and impress of no ordinary genius; that they are bespangled with gems of genuine poetry; and that their unpretending author well deserves--what he will doubtless obtain--the countenance and support of a discerning public. nature is not an aristocrat to the plough-boy following his team a-field--to the shepherd tending his flocks in the wilderness--or to the rude cutter of stone, cramped over his rough occupation in the wooden shed--she sometimes dispenses her richest and rarest gifts as liberally as to the proud patrician, or the titled representative of a long line of illustrious ancestry. she is no respecter of persons; and all other distinctions yield to the title which her favours confer. the names, be they ever so humble, which she illustrates, need no other decoration to recommend them; and hence, even that of our 'journeyman mason' may yet be destined to take its place with those of men who, like him, first poured their 'wood-notes wild' in the humblest and lowliest sphere of life, but, raised into deathless song, have become familiar as household words to all who love and admire the unsophisticated productions of native genius." the late dr. james browne of edinburgh, author of the "history of the highlands," and working editor of the "encyclopædia britannica," was, as i afterwards learned, the writer of this over-eulogistic, but certainly, in the circumstances, generous critique. ultimately i found my circle of friends very considerably enlarged by the publication of my verses and letters. mr. isaac forsyth of elgin, the brother and biographer of the well-known joseph forsyth, whose classical volume on italy still holds its place as perhaps the best work to which the traveller of taste in that country can commit himself, exerted himself, as the most influential of north-country booksellers, with disinterested kindness in my behalf. the late sir thomas dick lauder, too, resident at that time at his seat of relugas in moray, lent me, unsolicited, his influence; and, distinguished by his fine taste and literary ability, he ventured to pledge both in my favour. i also received much kindness from the late miss dunbar of boath--a literary lady of the high type of the last age, and acquainted in the best literary circles, who, now late in life, admitted amid her select friends one friend more, and cheered me with many a kind letter, and invited my frequent visits to her hospitable mansion. if, in my course as a working man, i never incurred pecuniary obligation, and never spent a shilling for which i had not previously laboured, it was certainly not from want of opportunity afforded me. miss dunbar meant what she said, and oftener than once did she press her purse on my acceptance. i received much kindness, too, from the late principal baird. the venerable principal, when on one of his highland journeys--benevolently undertaken in behalf of an educational scheme of the general assembly, in the service of which he travelled, after he was turned of seventy, more than eight thousand miles--had perused my verses and letters; and, expressing a strong desire to know their author, my friend the editor of the _courier_ despatched one of his apprentices to cromarty, to say that he thought the opportunity of meeting with such a man ought not to be neglected. i accordingly went up to inverness, and had an interview with dr. baird. i had known him previously by name as one of the correspondents of burns, and the editor of the best edition of the poems of michael bruce; and, though aware at the time that his estimate of what i had done was by much too high, i yet felt flattered by his notice. he urged me to quit the north for edinburgh. the capital furnished, he said, the proper field for a literary man in scotland. what between the employment furnished by the newspapers and the magazines, he was sure i would effect a lodgment, and work my way up; and until i gave the thing a fair trial, i would, of course, come and live with him. i felt sincerely grateful for his kindness, but declined the invitation. i did think it possible, that in some subordinate capacity--as a concocter of paragraphs, or an abridger of parliamentary debates, or even as a writer of occasional articles--i might find more remunerative employment than as a stone-mason. but though i might acquaint myself in a large town, when occupied in this way, with the world of books, i questioned whether i could enjoy equal opportunities of acquainting myself with the occult and the new in natural science, as when plying my labours in the provinces as a mechanic. and so i determined that, instead of casting myself on an exhausting literary occupation, in which i would have to draw incessantly on the stock of fact and reflection which i had already accumulated, i should continue for at least several years more to purchase independence by my labours as a mason, and employ my leisure hours in adding to my fund, gleaned from original observation, and in walks not previously trodden. the venerable principal set me upon a piece of literary taskwork, which, save for his advice, i would never have thought of producing, and of which these autobiographic chapters are the late but legitimate offspring. "literary men," he said, "are sometimes spoken of as consisting of two classes--the educated and the uneducated; but they must all alike have an education before they can become literary men; and the less ordinary the mode in which the education has been acquired, the more interesting always is the story of it. i wish you to write for me an account of yours." i accordingly wrote an autobiographic sketch for the principal, which brought up my story till my return, in , from the south country to my home in the north, and which, though greatly overladen with reflection and remark, has preserved for me both the thoughts and incidents of an early time more freshly than if they had been suffered to exist till now as mere recollections in the memory. i next set myself to record, in a somewhat elaborate form, the traditions of my native place and the surrounding district; and, taking the work very leisurely, not as labour, but as amusement--for my labours, as at an earlier period, continued to be those of the stone-cutter--a bulky volume grew up under my hands. i had laid down for myself two rules. there is no more fatal error into which a working man of a literary turn can fall, than the mistake of deeming himself too good for his humble employments; and yet it is a mistake as common as it is fatal. i had already seen several poor wretched mechanics, who, believing themselves to be poets, and regarding the manual occupation by which they could alone live in independence as beneath them, had become in consequence little better than mendicants--too good to work for their bread, but not too good virtually to beg it; and, looking upon them as beacons of warning, i determined that, with god's help, i should give their error a wide offing, and never associate the ideas of meanness with an honest calling, or deem myself too good to be independent. and, in the second place, as i saw that the notice, and more especially the hospitalities, of persons in the upper walks, seemed to exercise a deteriorating effect on even strong-minded men in circumstances such as mine, i resolved rather to avoid than court the attentions from this class which were now beginning to come my way. johnson describes his "ortogrul of basra" as a thoughtful and meditative man; and yet he tells us, that after he had seen the palace of the vizier, and "admired the walls hung with golden tapestry, and the floors covered with silken carpets, he despised the simple neatness of his own little habitation." and the lesson of the fiction is, i fear, too obviously exemplified in the real history of one of the strongest-minded men of the last age--robert burns. the poet seems to have left much of his early complacency in his humble home behind him, in the splendid mansions of the men who, while they failed worthily to patronize him, injured him by their hospitalities. i found it more difficult, however, to hold by this second resolution than by the first. as i was not large enough to be made a lion of, the invitations which came my way were usually those of real kindness; and the advances of kindness i found it impossible always to repel; and so it happened that i did at times find myself in company in which the working man might be deemed misplaced and in danger. on two several occasions, for instance, after declining previous invitations not a few, i had to spend a week at a time, as the guest of my respected friend miss dunbar of boath; and my native place was visited by few superior men that i had not to meet at some hospitable board. but i trust i may say, that the temptation failed to injure me; and that on such occasions i returned to my obscure employments and lowly home, grateful for the kindness i had received, but in no degree discontented with my lot. miss dunbar belonged, as i have said, to a type of literary lady now well-nigh passed away, but of which we find frequent trace in the epistolary literature of the last century. the class comes before us in elegant and tasteful letters, indicative of minds imbued with literature, though mayhap not ambitious of authorship, and that show what ornaments their writers must have proved of the society to which they belonged, and what delight they must have given to the circles in which they more immediately moved. the lady russel, the lady luxborough, the countess of pomfret, mrs. elizabeth montague, &c. &c.,--names well fixed in the epistolary literature of england, though unknown in the walks of ordinary authorship--may be regarded as specimens of the class. even in the cases in which its members did become authoresses, and produced songs and ballads instinct with genius, they seem to have had but little of the author's ambition in them; and their songs, cast carelessly upon the waters, have been found, after many days, preserved rather by accident than design. the lady wardlaw, who produced the noble ballad of "hardyknute"--the lady ann lindsay, who wrote "auld robin gray"--the miss blamire, whose "nabob" is so charming a composition, notwithstanding its unfortunately prosaic name--and the late lady nairne, authoress of the "land o' the leal," "john tod," and the "laird o' cockpen"--are specimens of the class that fixed their names among the poets with apparently as little effort or design as singing birds pour forth their melodies. the north had, in the last age, its interesting group of ladies of this type, of whom the central figure might be regarded as the late mrs. elizabeth rose of kilravock, the correspondent of burns, and the cousin and associate of henry mackenzie, the "man of feeling." mrs. rose seems to have been a lady of a singularly fine mind--though a little touched, mayhap, by the prevailing sentimentalism of the age. the mistress of harley, miss walton, might have kept exactly such journals as hers; but the talent which they exhibited was certainly of a high order; and the feeling, though cast in a somewhat artificial mould, was, i doubt not, sincere. portions of these journals i had an opportunity of perusing when on my visit to my friend miss dunbar; and there is a copy of one of them now in my possession. another member of this group was the late mrs. grant of laggan--at the time when it existed unbroken, the mistress of a remote highland manse, and known but to her personal friends by those earlier letters which form the first half of her "letters from the mountains," and which, in ease and freshness, greatly surpass aught which she produced after she began her career of authorship. not a few of her letters, and several of her poems, were addressed to my friend miss dunbar. some of the other members of the group were greatly younger than mrs. grant and the lady of kilravock. and of these, one of the most accomplished was the late lady gordon cumming of altyre, known to scientific men by her geologic labours among the ichthyolitic formations of moray, and mother of the famous lion-hunter, mr. gordon cumming. my friend miss dunbar was at this time considerably advanced in life, and her health far from good. she possessed, however, a singular buoyancy of spirits, which years and frequent illness had failed to depress; and her interest and enjoyment in nature and in books remained as high as when, long before, her friend mrs. grant had addressed her as "helen, by every sympathy allied, by love of virtue and by love of song, compassionate in youth and beauty's pride." her mind was imbued with literature, and stored with literary anecdote: she conversed with elegance, giving interest to whatever she touched; and, though she seemed never to have thought of authorship in her own behalf, she wrote pleasingly and with great facility, in both prose and verse. her verses, usually of a humorous cast, ran trippingly off the tongue, as if the words had dropped by some happy accident--for the arrangement bore no mark of effort--into exactly the places where they at once best brought out the writer's meaning, and addressed themselves most pleasingly to the ear. the opening stanzas of a light _jeu d'esprit_ on a young naval officer engaged in a lady-killing expedition in cromarty, dwell in my memory; and--first premising, by way of explanation, that miss dunbar's brother, the late baronet of boath, was a captain in the navy, and that the lady-killer was his first lieutenant--i shall take the liberty of giving all i remember of the piece, as a specimen of her easy style:-- "in cromarty bay, as the 'driver' snug lay, the lieutenant would venture ashore and, a figure to cut, from the head to the foot he was fashion and finery all o'er. a hat richly laced, to the left side was placed, which made him look martial and bold; his coat of true blue was spick and span new. and the buttons were burnished with gold. his neckcloth well puffed. which six handkerchiefs stuffed, and in colour with snow might have vied, was put on with great care, as a bait for the fair, and the ends in a love-knot were tied," &c. &c. i greatly enjoyed my visits to this genial-hearted and accomplished lady. no chilling condescensions on her part measured out to me my distance: miss dunbar took at once the common ground of literary tastes and pursuits; and if i did not feel my inferiority there, she took care that i should feel it nowhere else. there was but one point on which we differed. while hospitably extending to me every facility for visiting the objects of scientific interest in her neighbourhood--such as those sand-wastes of culbin in which an ancient barony finds burial, and the geologic sections presented by the banks of the findhorn--she was yet desirous to fix me down to literature as my proper walk; and i, on the other hand, was equally desirous of escaping into science. footnotes: [ ] i am reminded by the editor of the _courier_, in a very kind critique on the present volume, of a passage in the history of my little work which had escaped my memory. "it had come," he states, "to the knowledge of sir walter scott, who endeavoured to procure a copy after the limited impression was exhausted." [ ] the following are the opening stanzas of the piece--quite as obnoxious to criticism, i fear, as those selected by walsh:-- "have ye not seen, on winter's eve, when snow-rack dimm'd the welkin's face. borne wave-like, by the fitful breeze. the snow-wreath shifting place? silent and slow as drifting wreath. ere day, the clans from preston hill moved downward to the vale beneath:-- dark was the scene and still! in stormy autumn day, when sad the boding peasant frets forlorn, have ye not seen the mountain stream bear down the standing corn? at dawn, when preston bog was cross'd, like mountain stream that bursts its banks. charged wild those celtic hearts of fire. on cope's devoted ranks. have ye not seen, from lonesome waste, the smoke-tower rising tall and slow, o'erlooking, like a stately tree, the russet plain below? and have ye mark'd that pillar'd wreath, when sudden struck by northern blast, amid the low and stunted heath, in broken volumes cast? at sunrise, as by northern blast the pillar'd smoke is roll'd away. fled all that cloud of saxon war. in headlong disarray." * * * chapter xxi. "he who, with pocket hammer, smites the edge of luckless rock or prominent stone, disguised in weather stains, or crusted o'er by nature with her first growths--detaching by the stroke a chip or splinter, to resolve his doubts; and, with that ready answer satisfied, the substance classes by some barbarous name. and hurries on."--wordsworth. in the course of my two visits to miss dunbar, i had several opportunities of examining the sand-wastes of culbin, and of registering some of the peculiarities which distinguish the arenaceous sub-aërial formation from the arenaceous sub-aqueous one. of the present surface of the earth, considerably more than six millions of square miles are occupied in africa and asia alone by sandy deserts. with but the interruption of the narrow valley of the nile, an enormous zone of arid sand, full nine hundred miles across, stretches from the eastern coast of africa to within a few days' journey of the chinese frontier: it is a belt that girdles nearly half the globe;--a vast "ocean," according to the moors, "without water." the sandy deserts of the rainless districts of chili are also of great extent: and there are few countries in even the higher latitudes that have not their tracts of arenaceous waste. these sandy tracts, so common in the present scene of things, could not, i argued, be restricted to the recent geologic periods. they must have existed, like all the commoner phenomena of nature, under every succeeding system in which the sun shone, and the winds blew, and ocean-beds were upheaved to the air and the light, and the waves threw upon the shore, from arenaceous sea-bottoms, their accumulations of light sand. and i was now employed in acquainting myself with the marks by which i might be able to distinguish sub-aërial from sub-aqueous formations, among the ever-recurring sandstone beds of the geologic deposits. i have spent, when thus engaged, very delightful hours amid the waste. in pursuing one's education, it is always very pleasant to get into those _forms_ that are not yet introduced into any school. one of the peculiarities of the sub-aërial formation which i at this time detected struck me as curious. on approaching, among the sand-hills, an open level space, covered thickly over with water-rolled pebbles and gravel, i was surprised to see that, dry and hot as the day was elsewhere, the little open space seemed to have been subjected to a weighty dew or smart shower. the pebbles glistened bright in the sun, and bore the darkened hue of recent wet. on examination, however, i found that the rays were reflected, not from wetted, but from polished surfaces. the light grains of sand, dashed against the pebbles by the winds during a long series of years--grain after grain repeating its minute blow, where, mayhap, millions of grains had struck before--had at length given a resinous-looking, uneven polish to all their exposed portions, while the portions covered up retained the dull unglossy coat given them of old by the agencies of friction and water. i have not heard the peculiarity described as a characteristic of the arenaceous deserts; but though it seems to have escaped notice, it will, i doubt not, be found to obtain wherever there are sands for the winds to waft along, and hard pebbles against which the grains may be propelled. in examining, many years after, a few specimens of silicified wood brought from the egyptian desert, i at once recognised on their flinty surfaces the resinous-like gloss of the pebbles of culbin; nor can i doubt that, if geology has its sub-aërial formations of consolidated sand, they will be found characterized by their polished pebbles. i marked several other peculiarities of the formation. in some of the abrupter sections laid open by the winds, tufts of the bent-grass (_arundo arenaria_--common here, as in all sandy wastes) that had been buried up where they grew, might be distinctly traced, each upright in itself, but rising tuft above tuft in the steep angle of the hillock which they had originally covered. and though, from their dark colour, relieved against the lighter hue of the sand, they reminded me of the carbonaceous markings of sandstone of the coal measures, i recognised at least _their arrangement_ as unique. it seems to be such an arrangement--sloping in the general line, but upright in each of the tufts--as could take place in only a sub-aërial formation. i observed further, that in frequent instances there occurred on the surface of the sand, around decaying tufts of the bent-grass, deeply-marked circles, as if drawn by a pair of compasses or a trainer--effects apparently of eddy winds whirling round, as on a pivot, the decayed plants; and yet further, that footprints, especially those of rabbits and birds, were not unfrequent in the waste. and as lines of stratification were, i found, distinctly preserved in the formation, i deemed it not improbable that, in cases in which high winds had arisen immediately after tracts of wet weather, and covered with sand, rapidly dried on the heights, the damp beds in the hollows, both the circular markings and the footprints might remain fixed in the strata, to tell of their origin. i found in several places, in chasms scooped out by a recent gale, pieces of the ancient soil laid bare, which had been covered up by the sand-flood nearly two centuries before. in one of the openings the marks of the ancient furrows were still discernible; in another, the thin stratum of ferruginous soil had apparently never been brought under the plough; and i found it charged with roots of the common brake (_pteris aquilina_), in a perfect state of keeping, but black and brittle as coal. beneath this layer of soil lay a thin deposit of the stratified gravel of what is now known as the later glacial period--the age of _osars_ and moraines; and beneath all--for the underlying old red sandstone of the district is not exposed amid the level wastes of culbin--rested the boulder clay, the memorial of a time of submergence, when scotland sat low in the sea as a wintry archipelago of islands, brushed by frequent icebergs, and when sub-arctic molluscs lived in her sounds and bays. a section of a few feet in vertical extent presented me with four distinct periods. there was, first, the period of the sand-flood, represented by the bar of pale-sand; then, secondly, the period of cultivation and human occupancy, represented by the dark plough-furrowed belt of hardened soil; thirdly, there was the gravel; and, fourthly, the clay. and that shallow section exhausted the historic ages, and more; for the double band of gravel and clay belonged palpably to the geologic ages, ere man had appeared on our planet. there had been found in the locality, only a few years previous to this time, a considerable number of stone arrow-heads--some of them only partially finished, and some of them marred in the making, as if some fletcher of the stone age had carried on his work on the spot; and all these memorials of a time long anterior to the first beginnings of history in the island were restricted to the stratum of hardened mould. i carried on my researches in this--what i may term the chronological--direction, in connexion with the old-coast line, which, as i have already said, is finely developed in the neighbourhood of cromarty on both sides of the firth, and represented along the precipices of the sutors by its line of deep caves, into which the sea never now enters. and it, too, pressed upon me the fact of the amazing antiquity of the globe. i found that the caves hollowed by the surf--when the sea stood from fifteen to five-and-twenty feet above its present level, or, as i should perhaps rather say, when the land sat that much lower--were deeper, on the average, by about one-third, than those caves of the present coast-line that are still in the course of being hollowed by the waves. and yet the waves have been breaking against the present coast-line during the whole of the historic period. the ancient wall of antoninus, which stretched between the firths of forth and clyde, was built at its terminations with reference to the existing levels; and ere caesar landed in britain, st. michael's mount was connected with the mainland, as now, by a narrow neck of beach laid bare by the ebb, across which, according to diodorus siculus, the cornish miners used to drive, at low water, their carts laden with tin. if the sea has stood for two thousand six hundred years against the present coast-line--and no geologist would fix his estimate of the term lower--then must it have stood against the old line, ere it could have excavated caves one-third deeper than the modern ones, three thousand nine hundred years. and both sums united more than exhaust the hebrew chronology. yet what a mere beginning of geologic history does not the epoch of the old coast-line form! it is but a starting-point from the recent period. not a single shell seems to have become extinct during the last six thousand years. the organisms which i found deeply embedded in the soil beneath the old coast-line were exactly those which still live in our seas; and i have been since told by mr. smith of jordanhill, one of our highest authorities on the subject, that he detected only three shells of the period with which he was not familiar as existing forms, and that he subsequently met with all three, in his dredging expeditions, still alive. the six thousand years of human history form but a portion of the geologic day that is passing over us: they do not extend into the _yesterday_ of the globe, far less touch the myriads of ages spread out beyond. dr. chalmers had taught, more than a quarter of a century previous to this time, that the scriptures do not fix the antiquity of the earth. "if they fix anything," he said, "it is only the antiquity of the human species." the doctor, though not practically a geologist at the time, had shrewdly weighed both the evidence adduced and the scientific character of the men who adduced it, and arrived at a conclusion, in consequence, which may now be safely regarded as the final one. i, on the other hand, who knew comparatively little about the standing of the geologists, or the weight which ought to attach to their testimony, based my findings regarding the vast antiquity of the earth on exactly the data on which they had founded theirs; and the more my acquaintance with the geologic deposits has since extended, the firmer have my convictions on the subject become, and the more pressing and inevitable have i felt the ever-growing demand for longer and yet longer periods for their formation. as certainly as the sun is the centre of our system, must our earth have revolved around it for millions of years. an american theologian, the author of a little book entitled the "epoch of creation," in doing me the honour of referring to my convictions on this subject, states, that i "betray indubitable tokens of being spell-bound to the extent of infatuation, by the foregone conclusion of" my "theory concerning the high antiquity of the earth, and the succession of animal and vegetable creations." he adds further, in an eloquent sentence, a page and a half long, that had i first studied and credited my bible, i would have failed to believe in successive creations and the geologic chronology. i trust, however, i may say i did first study and believe my bible. but such is the structure of the human mind, that, save when blinded by passion or warped by prejudice, it must yield an involuntary consent to the force of evidence; and i can now no more refuse believing, in opposition to respectable theologians such as mr. granville penn, professor moses stuart, and mr. eleazar lord, that the earth is of an antiquity incalculably vast, than i can refuse believing, in opposition to still more respectable theologians, such as st. augustine, lactantius, and turretine, that it has antipodes, and moves round the sun. and further, of this, men such as the messrs. penn, stuart, and lord may rest assured, that what i believe in this matter now, all theologians, even the weakest, will be content to believe fifty years hence. sometimes a chance incident taught me an interesting geological lesson. at the close of the year , a tremendous hurricane from the south and west, unequalled in the north of scotland, from at least the time of the great hurricane of christmas , blew down in a single hour four thousand full-grown trees on the hill of cromarty. the vast gaps and avenues which it opened in the wood above could be seen from the town; and no sooner had it begun to take off than i set out for the scene of its ravages. i had previously witnessed, from a sheltered hollow of the old coast-line, the extraordinary appearance of the sea. it would seem as if the very violence of the wind had kept down the waves. it brushed off their tops as they were rising, and swept along the spray in one dense cloud, white as driving snow, that rose high into the air as it receded from the shore, and blotted out along the horizon the line between sky and water. as i approached the wood, i met two poor little girls of from eight to ten years, coming running and crying along the road in a paroxysm of consternation; but, gathering heart on seeing me, they stood to tell that when the storm was at its worst they were in the midst of the falling trees. setting out for the hill on the first rising of the wind, in the expectation of a rich harvest of withered boughs, they had reached one of its most exposed ridges just as the gale had attained to its extreme height, and the trees began to crash down around them. their little tear-bestained countenances still continued to show how extreme the agony of their terror had been. they would run, they said, for a few paces in one direction, until some huge pine would come roaring down, and block up their path; when, turning with a shriek, they would run for a few paces in another; and then, terrified by a similar interruption, again strike off in a third. at length, after passing nearly an hour in the extremest peril, and in at least all the fear which the circumstances justified, they succeeded in making their way unhurt to the outer skirts of the wood. bewick would have found in the incident the subject of a vignette that would have told its own story. in getting into the thick of the trees, i was struck by the extraordinary character of the scene presented. in some places, greatly more than half their number lay stretched upon the ground. on the more exposed prominences of the hill, scarce a tree was left standing for acres together: they covered the slopes; tree stretched over tree like tiles on a roof, with here and there some shattered trunk whose top had been blown off, and carried by the hurricane some fifteen or twenty yards away, leaning in sad ruin over its fallen comrades. what, however, formed the most striking, because less expected, parts of the scene, were the tall walls of turf that stood up everywhere among the fallen trees, like the ruins of dismantled cottages. the granitic gneiss of the hill is covered by a thick deposit of the red boulder clay of the district, and the clay, in turn, by a thin layer of vegetable mould, interlaced in every direction by the tree roots, which, arrested in their downward progress by the stiff clay, are restricted to the upper layer. and, save where here and there i found some tree snapped across in the midst, or divested of its top, all the others had yielded at the line between the boulder clay and the soil, and had torn up, as they fell, vast walls of the felted turf, from fifteen to twenty feet in length, by from ten to twelve feet in height. there were quite enough of these walls standing up among the prostrate trees, to have formed a score of the eastern sultan's ruined villages; and they imparted to the scene one of its strangest features. i have mentioned in an early chapter, that the hill had its dense thickets, which, from the gloom that brooded in their recesses even at mid-day, were known to the boys of the neighbouring town as the "dungeons." they had now fared, however, in this terrible overturn, like dungeons elsewhere in times of revolution, and were all swept away; and piles of prostrate trees--in some instances ten or twelve in a single heap marked where they had stood. in several localities, where they fell over swampy hollows, or where deep-seated springs came gushing to the light, i found the water partially dammed up, and saw that, were they to be left to cumber the ground as the debris of forests destroyed by hurricanes in the earlier ages of scottish history would certainly have been left, the deep shade and the moisture could not have failed to induce a total change in the vegetation. i marked, too, the fallen trees all lying one way, in the direction of the wind; and the thought at once struck me, that in this recent scene of devastation i had the origin of full one-half of our scottish mosses exemplified. some of the mosses of the south date from the times of roman invasion. their lower tiers of trunks bear the mark of the roman axe; and in some instances, the sorely wasted axe itself--a narrow, oblong tool, somewhat resembling that of the american backwoodsman--has been found sticking in the buried stump some of our other mosses are of still more modern origin: there exist scottish mosses that seem to have been formed when robert the bruce felled the woods and wasted the country of john of lorn. but of the others, not a few have palpably owed their origin to violent hurricanes, such as the one which on this occasion ravaged the hill of cromarty. the trees which form their lower stratum are broken across, or torn up by the roots, _and their trunks all lie one way_. much of the interest of a science such as geology must consist in the ability of making dead deposits represent living scenes; and from this hurricane i was enabled to conceive, pictorially, if i may so express myself, of the origin of those comparatively recent deposits of scotland which, formed almost exclusively of vegetable matter, contain, with rude works of art, and occasionally remains of the early human inhabitants of the country, skeletons of the wolf, the bear, and the beaver, with horns of the _bos primigenius_ and _bos longifrons_, and of a gigantic variety of red deer, unequalled in size by animals of the same species in these latter ages. occasionally i was enabled to vivify in this way even the ancient deposits of the lias, with their vast abundance of cephalopodous mollusca--belemnites, ammonites, and nautili. my friend of the cave had become parish schoolmaster of nigg; and his hospitable dwelling furnished me with an excellent centre for exploring the geology of the parish, especially its liassic deposits at shandwick, with their huge gryphites and their numerous belemnites, of at least two species, comparatively rare at eathie--the _belemnite abreviatus_ and _belemnite elongatus_. i had learned that these curious shells once formed part of the internal framework of a mollusc more nearly akin to the cuttle-fishes of the present day than aught else that now exists; and the cuttle-fishes--not rare in at least one of their species (_loligo vulgare_) in the firth of cromarty--i embraced every opportunity of examining. i have seen from eighteen to twenty individuals of this species enclosed at once in the inner chamber of one of our salmon-wears. the greater number of these shoals i have ordinarily found dead, and tinged with various shades of green, blue, and yellow--for it is one of the characteristics of the creature to assume, when passing into a state of decomposition, a succession of brilliant colours; but i have seen from six to eight individuals of their number still alive in a little pool beside the nets, and still retaining their original pink tint, freckled with red. and these i have observed, as my shadow fell across their little patch of water, darting from side to side in panic terror within the narrow confines, emitting ink at almost every dart, until the whole pool had become a deep solution of sepia. some of my most interesting recollections of the cuttle-fish are associated, however, with the capture and dissection of a single specimen. the creature, in swimming, darts through the water much in the manner that a boy slides down an ice-crusted declivity, feet foremost;--the lower or nether extremities go first, and the head behind: it follows its tail, instead of being followed by it; and this curious peculiarity in its mode of progression, though, of course, on the whole, the mode best adapted to its conformation and instincts, sometimes proves fatal to it in calm weather, when not a ripple breaks upon the pebbles, to warn that the shore is near. an enemy appears: the creature ejects its cloud of ink, like a sharp-shooter discharging his rifle ere he retreats; and then, darting away, tail foremost, under cover of the cloud, it grounds itself high upon the beach, and perishes there. i was walking, one very calm day, along the cromarty shore, a little to the west of the town, when i heard a peculiar sound--a _squelch_, if i may employ such a word--and saw that a large loligo, fully a foot and a half in length, had thrown itself high and dry upon the beach. i laid hold of it by its sheath or sack; and the loligo, in turn, laid hold of the pebbles, apparently to render its abduction as difficult as possible, just as i have seen a boy, when borne off against his will by a stronger than himself, grasping fast to door-posts and furniture. the pebbles were hard and smooth, but the creature raised them very readily with his suckers. i subjected one of my hands to its grasp, and it seized fast hold; but though the suckers were still employed, it made use of them on a different principle. around the circular rim of each there is a fringe of minute thorns, hooked somewhat like those of the wild rose. in clinging to the hard polished pebbles, these were overlapped by a fleshy membrane, much in the manner that the cushions of a cat's paw overlap its claws when the animal is in a state of tranquillity; and by means of the projecting membrane, the hollow interior was rendered air-tight, and the vacuum completed: but in dealing with the hand--a soft substance--the thorns were laid bare, like the claws of a cat when stretched out in anger, and at least a thousand minute prickles were fixed in the skin at once. they failed to penetrate it, for they were short, and individually not strong; but, acting together by hundreds, they took at least a very firm hold. what follows may be deemed barbarous; but the men who gulp down at a sitting half-a-hundred live oysters to gratify their taste, may surely forgive me the destruction of a single mollusc to gratify my curiosity! i cut open the sack of the creature with a sharp penknife, and laid bare the viscera. what a sight for harvey, when prosecuting, in the earlier stages, his grand discovery of the circulation! _there_, in the centre, was the yellow muscular heart, propelling into the transparent, tubular arteries, the _yellow_ blood. beat--beat--beat:--i could see the whole as in a glass model; and all i lacked were powers of vision nice enough to enable me to detect the fluid passing through the minuter arterial branches, and then returning by the veins to the _two_ other hearts of the creature; for, strange to say, it is furnished with three. there in the midst i saw the yellow heart, and, lying altogether detached from it, two other deep-coloured hearts at the sides. i cut a little deeper. _there_ was the gizzard-like stomach, filled with fragments of minute mussel and crab shells; and _there_, inserted in the spongy, conical, yellowish-coloured liver, and somewhat resembling in form a florence flask, was the ink-bag distended, with its deep dark sepia--the identical pigment sold under that name in our colour shops, and so extensively used in landscape drawing by the limner. i then dissected and laid open the circular or ring-like brain that surrounds the creature's parrot-like beak, as if its _thinking_ part had no other vocation than simply to take care of the mouth and its pertinents--almost the sole employment, however, of not a few brains of a considerably higher order. i next laid open the huge eyes. they were curious organs, more simple in their structure than those of the true fishes, but admirably adapted, i doubt not, for the purposes of seeing. a camera obscura may be described as consisting of two parts--a lens in front, and a darkened chamber behind; but in the eyes of fishes, as in the brute and human eye, we find a third part added: there is a lens in the middle, a darkened chamber behind, and a lighted chamber, or rather vestibule, in front. now, this lighted vestibule--the cornea--is wanting in the eye of the cuttle-fish. the lens is placed in front, and the darkened chamber behind. the construction of the organ is that of a common camera obscura. i found something worthy of remark, too, on the peculiar style in which the chamber is darkened. in the higher animals it may be described as a chamber hung with black velvet--the _pigmentum nigrum_ which covers it is of the deepest black; but in the cuttle-fish it is a chamber hung with velvet, not of a black, but of a dark purple hue--the _pigmentum nigrum_ is of a purplish red colour. there is something interesting in marking this first departure from an invariable condition of eyes of the more perfect structure, and in then tracing the peculiarity downwards through almost every shade of colour, to the emerald-like eye-specks of the pecten, and the still more rudimentary red eye-specks of the star-fish. after examining the eyes, i next laid open, in all its length, from the neck to the point of the sack, the dorsal bone of the creature--its internal shell, i should rather say, for bone it has none. the form of the shell in this species is that of a feather, equally developed in the web on both sides. it gives rigidity to the body, and furnishes the muscles with a fulcrum; and we find it composed, like all other _shells_, of a mixture of animal matter and carbonate of lime. such was the lesson taught me in a single walk; and i have recorded it at some length. the subject of it, the loligo, has been described by some of our more distinguished naturalists, such as kirby in his bridgewater treatise, as "one of the most wonderful works of the creator;" and the reader will perhaps remember how fraught with importance to natural science an incident similar to the one related proved in the life of the youthful cuvier. it was when passing his twenty-second year on the sea-coast, near fiquainville, that this greatest of modern naturalists was led, by finding a cuttle-fish stranded on the beach, which he afterwards dissected, to study the anatomy and character of the mollusca. to me, however, the lesson served merely to vivify the dead deposits of the oolitic system, as represented by the lias of cromarty and ross. the middle and later ages of the great secondary division were peculiarly ages of the cephalopodous molluscs: their belemnites, ammonites, nautili, baculites, hamites, turrilites, and scaphites, belonged to the great natural class--singularly rich in its extinct orders and genera, though comparatively poor in its existing ones--which we find represented by the cuttle-fish; and when engaged in disinterring the remains of the earlier-born members of the family--ammonites, belemnites, and nautili--from amid the shales of eathie or the mud-stones of shandwick, the incident of the loligo has enabled me to conceive of them, not as mere dead remains, but as the living inhabitants of primæval seas, stirred by the diurnal tides, and lighted up by the sun. when pursuing my researches amid the deposits of the lias, i was conducted to an interesting discovery. there are two great systems of hills in the north of scotland--an older and a newer--that bisect each other like the furrows of a field that had first been ploughed across and then diagonally. the diagonal furrows, as the last drawn, are still very entire. the great caledonian valley, open from sea to sea, is the most remarkable of these; but the parallel valleys of the nairn, of the findhorn, and of the spey, are all well-defined furrows; nor are the mountain ridges which separate them less definitely ranged in continuous lines. the ridges and furrows of the earlier ploughing are, on the contrary, as might be anticipated, broken and interrupted: the effacing plough has passed over them: and yet there are certain localities in which we find the fragments of this earlier system sufficiently entire to form one of the main features of the landscape. in passing through the upper reaches of the moray firth, and along the caledonian valley, the cross furrows may be seen branching off to the west, and existing as the valleys of loch fleet, of the dornoch firth, of the firth of cromarty, of the bay of munlochy, of the firth of beauty, and, as we enter the highlands proper, as glen urquhart, glen morrison, glen garry, loch arkaig, and loch eil. the diagonal system--represented by the great valley itself, and known as the system of ben nevis and the ord of caithness in our own country, and, according to de beaumont, as that of mount pilate and coté d'or on the continent--was upheaved after the close of the oolitic ages. it was not until at least the period of the weald that its "hills had been formed and its mountains brought forth;" and in the line of the moray firth the lias and oolite lie uptilted, at steep angles, against the sides of its long ranges of precipice. it is not so easy determining the age of the older system. no formation occurs in the north of scotland between the lias and the old red sandstone: the vast carboniferous, permian, and triassic deposits are represented by a wide gap; and all that can be said regarding the older hills is, that they disturbed and bore up with them the old red sandstone; but that as there lay at their bases, at the time of their upheaval, no more modern rock to be disturbed, it seems impossible definitely to fix their era. neither does there appear among their estuaries or valleys any trace of the oolitic deposits. existing, in all probability, during even the times of the lias, as the sub-aërial framework of oolitic scotland--as the framework on which the oolitic vegetables grew--no deposit of the system could of course have taken place over them. i had not yet, however, formed any very definite idea regarding the two systems, or ascertained that they belonged apparently to a different time; and finding the lias upheaved against the steeper sides of the moray firth--one of the huge furrows of the more modern system--i repeatedly sought to find it uptilted also against the shores of the cromarty firth--one of the furrows of the greatly more ancient one. i had, however, prosecuted the search in a somewhat desultory manner; and as in the autumn of a pause of a few days took place in my professional labours between the completing of one piece of work and the commencement of another, i resolved on devoting the time to a thorough survey of the cromarty firth, in the hope of detecting the lias. i began my search at the granitic gneiss of the hill, and, proceeding westwards, passed in succession, in the ascending order, over the uptilted beds of the lower old red sandstone, from the great conglomerate base of the system, till i reached the middle member of the deposit, which consists, in this locality, of alternate beds of limestone, sandstone, and stratified clay, and which we find represented in caithness by the extensively developed flag-stones. and then, the rock disappearing, i passed over a pebbly beach mottled with boulders; and in a little bay not half a mile distant from the town, i again found the rock laid bare. i had long before observed that the rock rose to the surface in this little bay; i had even employed, when a boy, pieces of its stratified clay as slate-pencil; but i had yet failed minutely to examine it. i was now, however, struck by its resemblance, in all save colour, to the lias. the strata lay at a low angle: they were composed of an argillaceous shale, and abounded in limestone nodules; and, save that both shale and nodules bore, instead of the deep liassic grey, an olivaceous tint, i might have almost supposed i had fallen on a continuation of some of the eathie beds. i laid open a nodule with a blow of the hammer, and my heart leaped up when i saw that it enclosed an organism. a dark, ill-defined, bituminous mass occupied the centre; but i could distinguish what seemed to be spines and small ichthyic bones projecting from its edges; and when i subjected them to the scrutiny of the glass, unlike those mere chance resemblances which sometimes deceive for a moment the eye, the more distinct and unequivocal did their forms become. i laid open a second nodule. it contained a group of glittering rhomboidal scales, with a few cerebral plates, and a jaw bristling with teeth. a third nodule also supplied its organism, in a well-defined ichthyolite, covered with minute, finely-striated scales, and furnished with a sharp spine in the anterior edge of every fin. i eagerly wrought on, and disinterred, in the course of a single tide, specimens enough to cover a museum table; and it was with intense delight that, as the ripple of the advancing tide was rising against the pebbles, and covering up the ichthyolitic beds, i carried them to the higher slopes of the beach, and, seated on a boulder, began carefully to examine them in detail with a common botanist's microscope. but not a plate, spine, or scale, could i detect among their organisms, identical with the ichthyic remains of the lias. i had got amid the remains of an entirely different and incalculably more ancient creation. my new-found organisms represented, not the first, but merely the second age of vertebrate existence on our planet; but as the remains of the earlier age exist as the mere detached teeth and spines of placoids, which, though they give full evidence of the _existence_ of the fishes to which they belong, throw scarce any light on their structure, it is from the ganoids of this second age that the palæontologist can with certainty know under what peculiarities of form, and associated with what varieties of mechanism, vertebral life existed in the earlier ages of the world. in my new-found deposit--to which i soon added, however, within the limits of the parish, some six or eight deposits more, all charged with the same ichthyic remains--i found i had work enough before me for the patient study of years. chapter xxii. "they lay aside their private cares, to mend the kirk and state affairs; they'll talk o' patronage and priests, wi' kindling fury in their breasts; or tell what new taxation 's comin', an' ferlie at the folk in _lon'on_."--burns. we had, as i have already stated, no dissenters in the parish of cromarty. what were known as the haldanes' people, had tried to effect a lodgment among us in the town, but without success: in the course of several years they failed to acquire more than six or eight members; and these were not of the more solid people, but marked as an eccentric class, fond of argument, and possessed by a rage for the novel and the extreme. the leading teachers of the party were a retired english merchant and an ex-blacksmith, who, quitting the forge in middle life, had pursued the ordinary studies to no very great effect, and become a preacher. and both were, i believe, good men, but by no means prudent missionaries. they said very strong things against the church of scotland, in a place where the church of scotland was much respected; and it was observed, that while they did not do a great deal to convert the irreligious to christianity, they were exceedingly zealous in their endeavours to make the religious baptists. much to my annoyance in my younger days, they used to waylay uncle sandy on his return from the hill, on evenings when i had gone to get some lessons from him regarding sand-worms, or razor-fish, or the sea-hare, and engage him in long controversies about infant baptism and church establishments. the matters which they discussed were greatly too high for me, nor was i by any means an attentive listener; but i picked up enough to know that uncle sandy, though a man of slow speech, held stiffly to the establishment scheme of knox, and the defence of presbyterianism; and it did not require any particularly nice perceptive powers to observe that both his antagonists and himself used at times to get pretty warm, and to talk tolerably loud--louder, at least, than was at all necessary in the quiet evening woods. i remember, too, that in urging him to quit the national church for theirs, they usually employed language borrowed from the revelations; and that, calling his church _babylon_, they bade him come out of her, that he might not be a partaker of her plagues. uncle sandy had seen too much of the world, and read and heard too much of controversy, to be out of measure shocked by the phrase; but with a decent farmer of the parish the hard words of the proselytizers did them a mischief. the retired merchant had urged him to quit the establishment; and the farmer had replied by asking, in his simplicity, whether he thought he ought to leave his church to sink in that way? "yes," exclaimed the merchant, with great emphasis; "leave her to sink to her place--the lowest hell!" this was terrible: the decent farmer opened his huge eyes at hearing what he deemed a bold blasphemy. the church of which the baptist spoke was, in cromarty at least, the church of the _outed_ mr. hugh anderson, who gave up his all in the time of the persecution, for conscience' sake; it was the church of mr. gordon, whose ministry had been so signally countenanced during the period of the great revival; it was the church of devout mr. monro, and of worthy mr. smith, and of many a godly elder and god-fearing member who had held by christ the head; and yet here was it denounced as a church whose true place was hell. the farmer turned away, sick of the controversy; and the imprudent speech of the retired merchant flew like wildfire over the parish. "surely," says bacon, "princes have need, in tender matters and ticklish times, to beware what they say, especially in those short speeches which fly about like darts, and are thought to be shot out of their secret intentions." princes are, however, not the only men who would do well to beware of short speeches. the short speech of the merchant ruined the baptist cause in cromarty; and the two missionaries might, on its delivery, have just done, if they but knew the position to which it reduced them, what they were content to do a few years after--pack up their moveables and quit the place. having for years no antagonists to contend with outside the pale of the establishment, it was of course natural that we should find opponents within. but during the incumbency of mr. smith--the minister of the parish for the first one-and-twenty years of my life--even these were wanting; and we passed a very quiet time, undisturbed by controversy of any kind, political or ecclesiastical. nor were the first few years of mr. stewart's incumbency less quiet. the catholic relief bill was a pebble cast into the pool, but a very minute one; and the ripple which it raised caused scarce any agitation. mr. stewart did not see his way clearly through all the difficulties of the measure; but, influenced in part by some of his brethren in the neighbourhood, he at length made up his mind to petition against it; and to his petition, praying that no concessions should be made to the papists, greatly more than nineteen-twentieths of the male parishioners affixed their names. the few individuals who kept aloof were chiefly lads of an extra-liberal turn, devoid, like most extreme politicians, of the ordinary ecclesiastical sympathies of their countryfolk; and as i cultivated no acquaintance with them, and was more ecclesiastical than political in my leanings, i had the satisfaction of finding myself standing, in opposition to all my friends, on the catholic relief measure, in a respectable minority of one. even uncle sandy, after some little demur, and an explosion against the irish establishment, set off and signed the petition. i failed, however, to see that i was in the wrong. with the two great facts of the irish union and the irish church before me, i could not petition against roman catholic emancipation. i felt, too, that were i myself a roman catholic, i would listen to no protestant argument until what i held to be justice had first been done me. i would have at once inferred that a religion associated with what i deemed injustice was a false, not a true, religion; and, on the strength of the inference, would have rejected it without further inquiry; and could i fail to believe that what i myself would have done in the circumstances, many roman catholics were actually doing? and believing i could defend my position, which was certainly not an obtrusive one, and was at times assailed in conversation by my friends, in a way that showed, as i thought, they did not understand it, i sat down and wrote an elaborate letter on the subject, addressed to the editor of the _inverness courier_; in which, as i afterwards found, i was happy enough to anticipate in some points the line taken up, in his famous emancipation speech, by a man whom i had early learned to recognise as the greatest and wisest of scottish ministers--the late dr. chalmers. on glancing over my letter, however, and then looking round me on the good men among my townsfolk--including my uncle and my minister--with whom it would have the effect of placing me in more decided antagonism than any mere refusal to sign their petition, i resolved, instead of dropping it into the post-office, to drop it into the fire, which i accordingly did; and so the matter took end; and what i had to say in my own defence, and in that of emancipation, was in consequence never said. this, however, was but the mere shadow of a controversy; it was merely a possible controversy, strangled in the birth. but some three years after, the parish was agitated by a dire ecclesiastical dispute, which set us all together by the ears. the place had not only its parish church, but also its gaelic chapel, which, though on the ordinary foundation of a chapel of ease, was endowed, and under the patronage of the crown. it had been built about sixty years previous, by a benevolent proprietor of the lands of cromarty--"george ross, the scotch agent"--whom junius ironically described as the "trusted friend and worthy confidant of lord mansfield;" and who, whatever the satirist may have thought of either, was in reality a man worthy the friendship of the accomplished and philosophic lawyer. cromarty, originally a lowland settlement, had had from the reformation down till the latter quarter of the last century no gaelic place of worship. on the breaking up of the feudal system, however, the highlanders began to drop into the place in quest of employment; and george ross, affected by their uncared-for religious condition, built for them, at his own expense, a chapel, and had influence enough to get an endowment for its minister from the government. government retained the patronage in its own hands; and as the highlanders consisted of but labourers and farm servants, and the workers in a hempen manufactory, and had no manner of influence, their wishes were not always consulted in the choice of a minister. about the time of mr. stewart's appointment, through the late sir robert peel, who had courteously yielded to the wishes of the english congregation, the gaelic people had got a minister presented to them whom they would scarcely have chosen for themselves, but who had, notwithstanding, popular points about him. though not of high talent, he was frank and genial, and visited often, and conversed much; and at length the highlanders came to regard him as the very _beau-idéal_ of a minister. he and mr. stewart belonged to the antagonist parties in the church. mr. stewart took his place in the old presbyterian section, under chalmers and thomson; while the gaelic minister held by drs. inglis and cook: and so thoroughly were their respective congregations influenced by their views, that at the disruption in , while considerably more than nine-tenths of the english-speaking parishioners closed their connexion with the state, and became free churchmen, at least an equal proportion of the chapel highlanders clung to the establishment. curiously enough, however, there arose a controversy between the congregations at this time, in which each seemed, in relation to the general question at issue, to take the part proper to the other. i do not think the english congregation were in any degree jealous of the gaelic one. the english contained the _élite_ of the place--all its men of property and influence, from its merchants and heritors, down to the humblest of the class that afterwards became its ten-pound franchise-holders; whereas the gaelic people were, as i have said, simply poor labourers and weavers: and if the sense of superiority did at times show itself on the more potent side, it was only among the lowlier people of the english congregation. when, on a certain occasion, a stranger fell asleep in the middle of one of mr. stewart's best sermons, and snored louder than was seemly, an individual beside him was heard muttering, in a low whisper, that the man ought to be sent up to "_the gaelic_," for he was not fit to be among them; and there might be a few other similar manifestations; but the parties were not on a sufficiently equal level to enact the part of those rival congregations that are for ever bemoaning the shortcomings each of the other, and that in their days of fasting and humiliation have the sins of their neighbours at least as strongly before them as their own. but if the english congregation were not jealous of the gaelic one, the gaelic one, as was perhaps natural in their circumstances, were, i am afraid, jealous of the english: they were poor people, they used sometimes to say, but their souls were as precious as those of richer folk, and they were surely as well entitled to have their just rights as the english people--axioms which, i believe, no one in the other congregation disputed, or even canvassed at all. we were, however, all roused one morning to consider the case, by learning that on the previous day the minister of the gaelic chapel had petitioned the presbytery of the district, either to be assigned a parish within the bounds of the parish of cromarty, or to have the charge erected into a collegiate one, and his half of it, of course, rendered coordinate with mr. stewart's. the english people were at once very angry, and very much alarmed. as the two congregations were scattered all over the same piece of territory, it would be impossible to cut it up into two parishes, without separating between a portion of mr. stewart's people and their minister, and making them the parishioners of a man whom they had not yet learned to like; and, on the other hand, by erecting the charge into a collegiate one, the minister whom they had not yet learned to like would acquire as real a jurisdiction over them as that possessed by the minister of their choice. or--as the case was somewhat quaintly stated by one of themselves--by the one alternative "the gaelic man would become whole minister to the half of them, and by the other, half minister to the whole of them." and so they determined on making a vigorous resistance. mr. stewart himself, too, liked the move of his neighbour the gaelic minister exceedingly ill. he was not desirous, he said, to have a colleague thrust upon him in his charge, to keep him right on moderate principles--a benefit for which he had not bargained when he accepted the presentation; nor yet, as the other alternative, did he wish to see his living child, the parish, divided into two, and the half of it given to the strange claimant that was not its parent. there was another account, too, on which he disliked the movement: the two great parties in the church were equally represented at this time in the presbytery;--they had their three members apiece; and he, of course, saw that the introduction of the gaelic minister into it would have the effect of casting the balance in favour of moderatism. and so, as both minister and people were equally in earnest, counter petitions were soon got up, praying the presbytery, as a first step in the process, that copies of the gaelic minister's document should be served upon them. the presbytery decided, in terms of their prayer, that copies should be served; and the gaelic minister, on the somewhat extreme ground that the people had no right to appear in the business at all, appealed to the general assembly. and so the people had next to petition that venerable court in behalf of what they deemed their imperilled rights; while the gaelic congregation, under the full impression that their overbearing english neighbours were treating them "as if they had no souls," got up a counter petition, virtually to the effect that the parish might be either cut in two, and the half of it given to their minister, or that he might be at least made second minister to every man in it. the minister, however, finding at the general assembly that the ecclesiastical party on whose support he had relied were opposed _in toto_ to the erection of chapels of ease into regular charges, and that the peculiarities of the case were such as to cut off all chance of his being supported by their opponents, fell from his appeal, and the case was never called in court. some of our cromarty fisher-folk, who were staunch on the english side, though they could not quite see the merits, had rather a different version of the business. "the gaelic man had no sooner entered the kirk o' the general assembly," they said, "than the maister of the assembly rose, and, speaking very rough, said, 'ye contrarious rascal, what tak's you here? what are ye aye troubling that decent lad mr. stewart for? i'm sure he's no meddling wi' you! get about your business, ye contrarious rascal!'" i took an active part in this controversy; wrote petitions and statements for my brother parishioners, with paragraphs for the local newspapers, and a long letter for the _caledonian mercury_, in reply to a tissue of misrepresentation which appeared in that print, from the pen of one of the gaelic minister's legal agents; and, finally, i replied to a pamphlet by the same hand, which, though miserable as a piece of writing--for it resembled no other composition ever produced, save, mayhap, a very badly-written law paper--contained statements which i deemed it necessary to meet. and such were my first attempts in the rough field of ecclesiastical controversy--a field into which inclination would never have led me, but which has certainly lain very much in my way, and in which i have spent many a laborious hour. my first pieces were rather stiffly written, somewhat on the perilous model of junius; but as it was hardly possible to write so ill as my opponent, i could appeal to even his friends whether it was quite right of him to call me illiterate and untaught, in prose so much worse than my own. chiefly by getting the laughers now and then on my side, i succeeded in making him angry; and he replied to my jokes by _calling names_--a phrase, by the way, which, forgetting his watts' hymns, and failing to consult his johnson, he characterized as not english. i was, he said, a "shallow, pretending ninny;" an "impudent illiterate lad;" "a fanatic" and a "frantic person;" the "low underling of a faction," and "peter the hermit;" and, finally, as the sum-total of the whole he assured me that i stood in _his_ "estimation the most ignoble and despised in the whole range of the human species." this was frightful! but i not only outlived it all, but learned, i fear, after in this way first tasting blood, to experience a rather too keen delight in the anger of an antagonist. i may add, that when, some two or three years after the period of this controversy, the general assembly admitted what were known as the parliamentary ministers, and the ministers of chapels of ease, to a seat in the church courts, neither my townsmen nor myself saw aught to challenge in the arrangement. it contained none of the elements which had provoked our hostility in the cromarty chapel case: it did not make over the people of one minister to the charge of another, whom they would never have chosen for themselves; but, without encroaching on popular rights, equalized, on the presbyterian scheme, the standing of ministers and the claims of congregations. the next matter which engaged my townsfolk was a considerably more serious one. when, in , cholera first threatened the shores of britain, the bay of cromarty was appointed by government one of the quarantine ports; and we became familiar with the sight, at first deemed sufficiently startling, of fleets of vessels lying in the upper roadstead, with the yellow flag waving from their mast-tops. the disease, however, failed to find its way ashore; and, when, in the summer of the following year, it was introduced into the north of scotland, it went stalking around the town and parish for several months, without visiting either. it greatly more than decimated the villages of portmahomak and inver, and bore heavily on the parishes of nigg and urquhart, with the towns of inverness, nairn, avoch, dingwall, and rosemarkie; in fine, the quarantine seaport town that seemed at first to be most in danger from the disease, appeared latterly to be almost the only place of any size in the locality exempted from its ravages. it approached, however, alarmingly near. the opening of the cromarty firth is little more than a mile across; a glass of the ordinary power enables one to count every pane in the windows of the dwellings that mottle its northern shore, and to distinguish their inhabitants; and yet among these dwellings cholera was raging; and we could see, in at least one instance, a dead body borne forth by two persons on a hand-barrow, and buried in a neighbouring sand-bank. stories, too, of the sad fate of individuals with whom the townsfolk were acquainted, and who had resided in well-known localities, told among them with powerful effect. such was the general panic in the infected places, that the bodies of the dead were no longer carried to the churchyard, but huddled up in solitary holes and corners; and the pictures suggested to the fancy, of familiar faces lying uncoffined in the ground beside some lonely wood, or in some dark morass or heathy moor, were fraught to many with a terror stronger than that of death. we knew that the corpse of a young robust fisherman, who used occasionally to act as one of the cromarty ferrymen, and with whose appearance, in consequence, every one was familiar, lay festering in a sand-bank; that the iron frame of a brawny blacksmith was decomposing in a mossy hole beside a thorn-bush; that half the inhabitants of the little fishing village of inver were strewn in shallow furrows along the arid waste which surrounded their dwellings; that houses divested of their tenants, and become foul dens of contagion, had been set on fire and burnt to the ground; and that around the infected fishing-hamlets of hilton and balintore the country-people had drawn a sort of _barrière sanitaire_, and cooped up within the limits of their respective villages the wretched inhabitants. and in the general consternation--a consternation much more extreme than that evinced when the disease actually visited the place--it was asked by the townsfolk whether _they_ ought not so long as the place remained uninfected, to draw a similar _cordon_ round themselves. a public meeting was accordingly held, to deliberate on the best means of shutting themselves in; and at the meeting almost all the adult male inhabitants attended, with the exception of the gentlemen in the commission of the peace, and the town officials, who, though quite prepared to wink hard at our irregularities, failed to see that, on any grounds tenable in the eye of the law, they themselves could take a share in them. our meeting at first threatened to be stormy. the extra liberals, who, in the previous ecclesiastical struggle, had taken part to a man with the gaelic people, as they did, in the subsequent church controversy, with the court of session, began by an attack on the town justices. we might all see now, said a liberal writer lad who addressed us, how little these people were our friends. now when the place was threatened by the pestilence, they would do nothing for us; they would not even so much as countenance our meeting; we saw there was not one of them present: in short, they cared nothing at all about us, or whether we died or lived. but he and his friends would stand by us to the last; nay, while the magistrates were evidently afraid, with all their wealth, to move in the matter, terrified, no doubt, by the prosecutions for damages which might be instituted against them were they to stop the highways, and turn back travellers, he himself, though far from rich, would be our security against all legal processes whatever. this, of course, was very noble; all the more noble from the circumstance that the speaker could not, as the _gazette_ informed us, meet his own actual liabilities at the time, and was yet fully prepared, notwithstanding, to meet all our possible ones. up started, however, almost ere he had done speaking, a friend of the justices, and made so angry a speech in their defence, that the meeting threatened to fall into two parties, and explode in a squabble. i rose in the extremity, and, though unhappily no orator, addressed my townsfolk in a few homely sentences. cholera, i reminded them, was too evidently of neither party; and the magistrates were, i was sure, nearly as much frightened as we were. but they really could do nothing for us. in matters of life and death, however, when laws and magistrates failed to protect quiet people, the people were justified in asserting the natural right to protect themselves; and, whatever laws and lawyers might urge to the contrary, that right was now ours. in a neighbouring county, the inhabitants of certain infected villages were already fairly shut up amid their dwellings by the countryfolk around, who could themselves show a clean bill of health; and we, if in the circumstances of these villagers, would very possibly be treated after the same manner. and what remained to us in our actual circumstances was just to anticipate the process of being ourselves bottled in, by bottling the country out. the town, situated on a promontory, and approachable at only a few points, could easily be guarded; and instead of squabbling about the merits of justices of the peace--very likely somewhat conservative in their leanings--or of spirited reformers who would like very well to be justices of the peace also, and would doubtless make very excellent ones, i thought it would be far better for us immediately to form ourselves into a defence association, and proceed to regulate our watches and set our guards. my short speech was remarkably well received. there was a poor man immediately beside me, who was in great dread of cholera, and who actually proved one of its first victims in the place--for in little more than a week after he was in his grave--who backed me by an especially vigorous hear, hear!--and the answering hear, hears, of the meeting bore down all reply. we accordingly at once formed our defence association; and ere midnight our rounds and stations were marked out, and our watches set. all power passed at once out of the hands of the magistrates; but the worthy men themselves said very little about it; and we had the satisfaction of knowing that their families--especially their wives and daughters--were very friendly indeed both to the association and the temporary suspension of the law, and that, on both their own account and ours, they wished us all manner of success. we kept guard for several days. all vagabonds and trampers were turned back without remorse; but there was a respectable class of travellers from whom there was less danger to be apprehended; and with these we found it somewhat difficult to deal. i would have admitted them at once; but the majority of the association demurred;--to do that would be, according to corporal trim, to "set one man greatly over the head of another;" and it was ultimately agreed that, instead of at once admitting them, they should be first brought into a wooden building fitted up for the purpose, and thoroughly fumigated with sulphur and chloride of lime. i know not with whom the expedient first originated: it was said to have been suggested by some medical man who knew a great deal about cholera. and though, for my own part, i could not see how the demon of the disease was to be expelled by the steam of a little sulphur and chloride, as the evil spirit in tobit was expelled by the smoke of the fish's liver, it seemed to satisfy the association wonderfully well; and a stranger well smoked came to be regarded as safe. there was a day at hand which promised an unusual amount of smoking. the agitation of the reform bill had commenced;--a great court of appeal was on that day to hold at cromarty; and it was known that both a whig and tory party from inverness, in which cholera was raging at the time, would to a certainty attend it. what, it was asked, were we to do with the politicians--the formidable bankers, factors, and lawyers--who would form, we knew, the inverness cavalcade? individually, the question seemed to be asked under a sort of foreboding terror, that calculated consequences; but when the association came to ask it collectively, and to answer it in a body, it was in a bold tone, that set fear at defiance. and so it was resolved, _nem. con._, that the inverness politicians should be smoked like the others. my turn to mount guard had come round on the previous night at twelve o'clock; but i had calculated on being off the station ere the inverness people came up. unluckily, however, instead of being appointed a simple sentry, i was made officer for the night. it was the duty assigned to me to walk round the several posts, and see that the various sentinels were keeping a smart outlook, which i did very faithfully; but when the term of my watch had expired, i found no relieving officer coming up to take my place. the prudent man appointed on the occasion was, i feared, tiding over the coming difficulty in some quiet corner; but i continued my rounds, maugre the suspicion, in the hope of his appearance. and as i approached one of the most important stations--that on the great highway which connects the town of cromarty with kessock ferry, _there_ was the whig portion of the inverness cavalcade just coming up. the newly-appointed sentinel stood aside, to let his officer deal with the whig gentlemen, as, of course, best became both their quality and _his_ official standing. i would rather have been elsewhere; but i at once brought the procession to a stand. a man of high spirit and influence--a banker, and very much a whig--at once addressed me with a stern--"by what authority, sir?" by the authority, i replied, of five hundred able-bodied men in the neighbouring town, associated for the protection of themselves and their families. "protection against what?" "protection against the pestilence;--you come from an infected place." "do you know what you are doing, sir?" said the banker fiercely. "yes; doing what the law cannot do for us, but what we have determined to do for ourselves." the banker grew pale with anger; and he was afterwards heard to say, that had he had a pistol at the time, he would have shot upon the spot the man who stopped him; but not having a pistol, he could not shoot me; and so i sent him and his party away under an escort, to be smoked. and as they were somewhat obstreperous by the way, and knocked the hat of one of the guards over his nose, they got, in the fumigating process, as i was sorry to learn, a double portion of the sulphur and the chloride; and came into court, to contend with the tories, gasping for breath. i was aware i acted on this occasion a very foolish part;--i ought to a certainty to have run away on the approach of the inverness cavalcade; but the running away would have involved, according to rochester, an amount of moral courage which i did not possess. i fear, too. i must admit, that the rough tones of the banker's address stirred up what had long lain quietly enough in my veins--some of the wild buccaneering blood of john feddes and the old seafaring millers; and so i weakly remained at my post, and did what the association deemed my duty. i trust the banker did not recognise me, and that now, after the lapse of more than twenty years, he will be inclined to extend to me his forgiveness. i take this late opportunity of humbly begging his pardon, and of assuring him, that at the very time i brought him to bay i was heartily at one with him in his politics. but then my townsfolk, being much frightened, were perfectly impartial in smoking whigs and tories all alike; and i could bethink me of no eligible mode of exempting my friends from a process of fumigation which was, i daresay, very unpleasant, and in whose virtues my faith was assuredly not strong. when engaged, however, in keeping up our _cordon_ with apparent success, cholera entered the place in a way on which it was impossible we could have calculated. a cromarty fisherman had died of the disease at wick rather more than a month previous, and the clothes known to have been in contact with the body were burnt by the wick authorities in the open air. he had, however, a brother on the spot, who had stealthily appropriated some of the better pieces of dress; and these he brought home with him in a chest; though such was the dread with which he regarded them that for more than four weeks he suffered the chest to lie beside him unopened. at length, in an evil hour, the pieces of dress were taken out, and, like the "goodly babylonish garment" which wrought the destruction of achan and the discomfiture of the camp, they led, in the first instance, to the death of the poor imprudent fisherman, and to that of not a few of his townsfolk immediately after. he himself was seized by cholera on the following day; in less than two days more he was dead and buried; and the disease went creeping about the streets and lanes for weeks after--here striking down a strong man in the full vigour of middle life--there shortening, apparently by but a few months, the span of some worn-out creature, already on the verge of the grave. the visitation had its wildly picturesque accompaniments. pitch and tar were kept burning during the night in the openings of the infected lanes; and the unsteady light flickered with ghastly effect on house and wall, and tall chimney-top, and on the flitting figures of the watchers. by day, the frequent coffins, borne to the grave by but a few bearers, and the frequent smoke that rose outside the place from fires kindled to consume the clothes of the infected, had their sad and startling effect; a migration, too, of a considerable portion of the fisher population to the caves of the hill, in which they continued to reside till the disease left the town, formed a striking accompaniment of the visitation; and yet, curiously enough, as the danger seemed to increase the consternation lessened, and there was much less fear among the people when the disease was actually ravaging the place, than when it was merely stalking within sight around it. we soon became familiar, too, with its direst horrors, and even learned to regard them as comparatively ordinary and commonplace. i had read, about two years before, the passage in southey's "_colloquies_," in which sir thomas more is made to remark that modern englishmen have no guarantee whatever, in these latter times, that their shores shall not be visited, as of old, by devastating plagues. "as touching the pestilence," says sir thomas (or rather the poet in his name), "you fancy yourselves secure because the plague has not appeared among you for the last hundred and fifty years--a portion of time which, long as it may seem, compared with the brief term of mortal existence, is as nothing in the physical history of the globe. the importation of that scourge is as possible now as it was in former times; and were it once imported, do you suppose it would rage with less violence among the crowded population of your metropolis than it did before the fire? what," he adds, "if the sweating sickness, emphatically called the english disease, were to show itself again? can any cause be assigned why it is not as likely to break out in the nineteenth century as in the fifteenth?" and, striking as the passage is, i remembered perusing it with that incredulous feeling, natural to men in a quiet time, which leads them to draw so broad a line between the experience of history, if of a comparatively remote age, or of a distant place, and their own personal experience. in the loose sense of the sophist, it was contrary to my experience that britain should become the seat of any such fatal and widely-devastating disease as used to ravage it of old. and yet, now that i saw as terrible and unwonted an infliction as either the plague or the sweating sickness decimating our towns and villages, and the terrible scenes described by de foe and patrick walker fully rivalled, the feeling with which i came to regard it was one, not of strangeness, but of familiarity. when thus unsuccessfully employed in keeping watch and ward against our insidious enemy, the reform bill for scotland passed the house of lords, and became the law of the land. i had watched with interest the growth of the popular element in the country--had seen it gradually strengthening, from the despotic times of liverpool and castlereagh, through the middle period of canning and goderich, down till even wellington and peel, men of iron as they were, had to yield to the pressure from without, and to repeal first the test and corporation acts, and next to carry, against their own convictions, the great roman catholic emancipation measure. the people, during a season of undisturbed peace, favourable to the growth of opinion, were becoming more decidedly a power in the country than they had ever been before; and of course, as one of the people, and in the belief, too, that the influence of the many would be less selfishly exerted than that of the few, i was pleased that it should be so, and looked forward to better days. for myself personally i expected nothing. i had early come to see that toil, physical or intellectual, was to be my portion throughout life, and that through no possible improvement in the government of the country could i be exempted from labouring for my bread. from state patronage i never expected anything, and i have received from it about as much as i ever expected. i was employed in labouring pretty hard for my bread one fine evening in the summer of --engaged in hewing with bare breast and arms, in the neighbourhood of the harbour of cromarty, a large tombstone, which, on the following day, was to be carried across the ferry to a churchyard on the opposite side of the firth. a group of french fishermen, who had gathered round me, were looking curiously at my mode of working, and, as i thought, somewhat curiously at myself, as if speculating on the physical powers of a man with whom there was at least a possibility of their having one day to deal. they formed part of the crew of one of those powerfully-manned french luggers which visit our northern coasts every year, ostensibly with the design of prosecuting the herring fishery, but which, supported mainly by large government bounties, and in but small part by their fishing speculations, are in reality kept up by the state as a means of rearing sailors for the french navy. their lugger--an uncouth-looking vessel, representative rather of the navigation of three centuries ago than of that of the present day--lay stranded in the harbour beside us; and, their work over for the day, they seemed as quiet and silent as the calm evening whose stillness they were enjoying; when the letter-carrier of the place came up to where i was working, and handed me, all damp from the press, a copy of the _inverness courier_, which i owed to the kindness of its editor. i was at once attracted by the heading, in capitals, of his leading article--"revolution in france--flight of charles x."--and pointed it out to the frenchmen. none of them understood english; but they could here and there catch the meaning of the more important words, and, exclaiming "_révolution en france!!--fuite de charles x.!!_"--they clustered round it in a state of the extremest excitement, gabbling faster and louder than thrice as many englishmen could have done in any circumstances. at length, however, their resolution seemed taken: curiously enough, their lugger bore the name of _"charles x.;"_ and one of them, laying hold of a large lump of chalk, repaired to the vessel's stern, and by covering over the white-lead letters with the chalk, effaced the royal name. charles was virtually declared by the little bit of france that sailed in the lugger, to be no longer king; and the incident struck me, trivial as it may seem, as significantly illustrative of the extreme slightness of that hold which the rulers of modern france possess on the affections of their people. i returned to my home as the evening darkened, more moved by this unexpected revolution than by any other political event of my time--brimful of hope for the cause of freedom all over the civilized world, and, in especial--misled by a sort of _analogical experience_--sanguine in my expectations for france. it had had, like our own country, its first stormy revolution, in which its monarch had lost his head; and then its cromwell, and then its restoration, and its easy, luxurious king, who, like charles ii., had died in possession of the throne, and who had been succeeded by a weak bigot brother, the very counterpart of james vii. and now, after a comparatively orderly revolution like that of , the bigot had been dethroned, and the head of another branch of the royal family called in to enact the part of william iii. the historical parallel seemed complete; and could i doubt that what would next follow would be a long period of progressive improvement, in which the french people would come to enjoy, as entirely as those of britain, a well-regulated freedom, under which revolutions would be unnecessary, mayhap impossible? was it not evident, too, that the success of the french in their noble struggle would immediately act with beneficial effect on the popular cause in our own country and everywhere else, and greatly quicken the progress of reform? and so i continued to watch with interest the course of the reform bill, and was delighted to see it, after a passage singularly stormy and precarious, at length safely moored in port. in some of the measures, too, to which it subsequently led, i greatly delighted, especially in the emancipation of our negro slaves in the colonies. nor could i join many of my personal friends in their denunciation of that appropriation measure, as it was termed--also an effect of the altered constituency--which suppressed the irish bishoprics. as i ventured to tell my minister, who took the other side--if a protestant church failed, after enjoying for three hundred years the benefits of a large endowment, and every advantage of position which the statute-book could confer, to erect herself into the church of the many, it was high time to commence dealing with her in her true character--as the church of the few. at home, however, within the narrow precincts of my native town, there were effects of the measure which, though comparatively trifling, i liked considerably worse than the suppression of the bishoprics. it broke up the townsfolk into two portions--the one consisting of elderly or middle-aged men, who had been in the commission of the peace ere the passing of the bill, and who now, as it erected the town into a parliamentary burgh, became our magistrates, in virtue of the support of a majority of the voters; and a younger and weaker, but clever and very active party, few of whom were yet in the commission of the peace, and who, after standing unsuccessfully for the magistracy, became the leaders of a patriotic opposition, which succeeded in rendering the seat of justice a rather uneasy one in cromarty. the younger men were staunch liberals, but great moderates--the elder, sound evangelicals, but decidedly conservative in their leanings; and as i held ecclesiastically by the one party, and secularly by the other, i found my position, on the whole, a rather anomalous one. both parties got involved in law-suits. when the whig members of parliament for the county and burgh came the way, they might be seen going about the streets arm-in-arm with the young whigs, which was, of course, a signal honour; and during the heat of a contested election, young whiggism, to show itself grateful, succeeded in running off with a conservative voter, whom it had caught in his cups, and got itself involved in a law-suit in consequence, which cost it several hundred pounds. the conservatives, on the other hand, also got entangled in an expensive law-suit. the town had its annual fair, at which from fifty to a hundred children used to buy gingerbread, and which had held for many years at the eastern end of the town links. through, however, some unexplained piece of strategy on the part of the young liberals, a market-day came round, on which the gingerbread-women took their stand on a green a little above the harbour; and, of course, where the gingerbread was, there the children were gathered together; and the magistrates, astonished, visited the spot in order to ascertain, if possible, the philosophy of the change. they found the ground occupied by a talkative pedlar, who stood up strongly for the young liberals and the new side. the magistrates straightway demanded the production of his license. the pedlar had none. and so he was apprehended, and summarily tried, on a charge of contravening the statute geo. iii. cap. ; and, being found guilty of hawking without a license, he was committed to prison. the pedlar, backed, it was understood, by the young liberals, raised an action for wrongous imprisonment; and, on the ground that the day on which he had sold his goods was a fair or market-day, on which anybody might sell anything, the magistrates were cast in damages. i liked the law-suits very ill, and held that the young liberals would have been more wisely employed in making money by their shops and professions--secure that the coveted honours would ultimately get into the wake of the good bank-accounts--than that they should be engaged either in scattering their own means in courts of law, or in impinging on the means of their neighbours. and ultimately i found my proper political position as a supporter in all ecclesiastical and municipal matters of my conservative townsmen, and a supporter in almost all the national ones of the whigs; whom, however, i always liked better, and deemed more virtuous, when they were out of office than when they were in. on one occasion i even became political enough to stand for a councillorship. my friends, chiefly through the death of elderly voters and the rise of younger men, few of whom were conservative, felt themselves getting weak in the place; and fearing that they could not otherwise secure a majority at the council board, they urged me to stand for one of the vacancies, which i accordingly did, and carried my election by a swimming majority. and in duly attending the first meeting of council, i heard an eloquent speech from a gentleman in the opposition, directed against the individuals who, as he finely expressed it, "were wielding the destinies of his native town;" and saw, as the only serious piece of business before the meeting, the councillors clubbing pennies a-piece, in order to defray, in the utter lack of town funds, the expense of a ninepenny postage. and then, with, i fear, a very inadequate sense of the responsibilities of my new office, i stayed away from the council board, and did nothing whatever in its behalf, with astonishing perseverance and success, for three years together. and thus began and terminated my municipal career--a career which, i must confess, failed to secure for me the thanks of my constituency; but then, on the other hand, i am not aware that the worthy people ever seriously complained. there was absolutely nothing to do in the councilship; and, unlike some of my brother office-bearers, the requisite nothing i did, quietly and considerately, and very much at my leisure, without any unnecessary display of stump-oratory, or of anything else. chapter xxiii. "days passed; an' now my patient steps that maiden's walks attend; my vows had reach'd that maiden's ear, ay, an' she ca'd me friend. an' i was bless'd as bless'd can be; the fond, daft dreamer hope ne'er dream'd o' happier days than mine, or joys o' ampler scope."--henrison's sang. i used, as i have said, to have occasional visitors when working in the churchyard. my minister has stood beside me for hours together, discussing every sort of subject, from the misdeeds of the moderate divines--whom he liked all the worse for being brethren of his own cloth--to the views of isaac taylor on the corruptions of christianity or the possibilities of the future state. strangers, too, occasionally came the way, desirous of being introduced to the natural curiosities of the district, more especially to its geology; and i remember first meeting in the churchyard, in this way, the late sir thomas dick lauder; and of having the opportunity afforded me of questioning, mallet in hand, the present distinguished professor of humanity in the edinburgh university,[ ] respecting the nature of the cohesive agent in the non-calcareous sandstone which i was engaged in hewing. i had sometimes a different, but not less interesting, class of visitors. the town had its small but very choice circle of accomplished intellectual ladies, who, earlier in the century, would have been perhaps described as members of the blue-stocking sisterhood; but the advancing intelligence of the age had rendered the phrase obsolete; and they simply took their place as well-informed, sensible women, whose acquaintance with the best authors was regarded as in no degree disqualifying them from their proper duties as wives or daughters. and my circle of acquaintance included the entire class. i used to meet them at delightful tea-parties, and sometimes borrowed a day from my work to conduct them through the picturesque burn of eathie, or the wild scenes of cromarty hill, or to introduce them to the fossiliferous deposits of the lias or the old red sandstone. and not unfrequently their evening walks used to terminate where i wrought, in the old chapel of st. regulus, or in the parish burying-ground, beside a sweet wooded dell known as the "ladies' walk;" and my labours for the day closed in what i always very much relished--a conversation on the last good book, or on some new organism, recently disinterred, of the secondary or palæozoic period. i had been hewing, about this time, in the upper part of my uncle's garden, and had just closed my work for the evening, when i was visited by one of my lady friends, accompanied by a stranger lady, who had come to see a curious old dial-stone which i had dug out of the earth long before, when a boy, and which had originally belonged to the ancient castle-garden of cromarty. i was standing with them beside the dial, which i had placed in my uncle's garden, and remarking, that as it exhibited in its structure no little mathematical skill, it had probably been cut under the eye of the eccentric but accomplished sir thomas urquhart; when a third lady, greatly younger than the others, and whom i had never seen before, came hurriedly tripping down the garden-walk, and, addressing the other two apparently quite in a flurry--"o, come, come away," she said, "i have been seeking you ever so long." "is this you, l----?" was the staid reply: "why, what now?--you have run yourself out of breath." the young lady was, i saw, very pretty; and though in her nineteenth year at the time, her light and somewhat _petite_ figure, and the waxen clearness of her complexion, which resembled rather that of a fair child than of a grown woman, made her look from three to four years younger. and as if in some degree still a child, her two lady friends seemed to regard her. she stayed with them scarce a minute ere she tripped off again; nor did i observe that she favoured me with a single glance. but what else could be expected by an ungainly, dust-besprinkled mechanic in his shirt sleeves, and with a leathern apron before him? nor _did_ the mechanic expect aught else; and when informed long after, by one whose testimony was conclusive on the point, that he had been pointed out to the young lady by some such distinguished name as "the cromarty poet," and that she had come up to her friends somewhat in a flurry, simply that she might have a nearer look of him, he received the intelligence somewhat with surprise. all the first interviews in all the novels i ever read are of a more romantic and less homely cast than the special interview just related; but i know not a more curious one. only a few evenings after, i met the same young lady, in circumstances of which the writer of a tale might have made a little more. i was sauntering, just as the sun was sinking, along one of my favourite walks on the hill--a tree-skirted glade--now looking out through the openings on the ever fresh beauties of the cromarty firth, with its promontories, and bays, and long lines of winding shore, and anon marking how redly the slant light fell through intersticial gaps on pale lichened trunks and huge boughs, in the deeper recesses of the wood--when i found myself unexpectedly in the presence of the young lady of the previous evening. she was sauntering through the wood as leisurely as myself--now and then dipping into a rather bulky volume which she carried, that had not in the least the look of a novel, and which, as i subsequently ascertained, was an elaborate essay on causation. we, of course, passed each other on our several ways without sign of recognition. quickening her pace, however, she was soon out of sight; and i just thought, on one or two occasions afterwards, of the apparition that had been presented as she passed, as much in keeping with the adjuncts--the picturesque forest and the gorgeous sunset. it would not be easy, i thought, were the large book but away, to furnish a very lovely scene with a more suitable figure. shortly after, i began to meet the young lady at the charming tea-parties of the place. her father, a worthy man, who, from unfortunate speculations in business, had met with severe losses, was at this time several years dead; and his widow had come to reside in cromarty, on a somewhat limited income, derived from property of her own. liberally assisted, however, by relations in england, she had been enabled to send her daughter to edinburgh, where the young lady received all the advantages which a first-rate education could confer. by some lucky chance, she was there boarded, with a few other ladies, in early womanhood, in the family of mr. george thomson, the well-known correspondent of burns; and passed under his roof some of her happiest years. mr. thomson--himself an enthusiast in art--strove to inoculate the youthful inmates of his house with the same fervour, and to develop whatever seeds of taste or genius might be found in them; and, characterized till the close of a life extended far beyond the ordinary term, by the fine chivalrous manners of the thorough gentleman of the old school, his influence over his young friends was very great, and his endeavours, in at least some of the instances, very successful. and in none, perhaps, was he more so than in the case of the young lady of my narrative. from edinburgh she went to reside with the friends in england to whose kindness she had been so largely indebted; and with them she might have permanently remained, to enjoy the advantages of superior position. she was at an age, however, which rarely occupies itself in adjusting the balance of temporal advantage; and her only brother having been admitted, through the interest of her friends, as a pupil into christ's hospital, she preferred returning to her widowed mother, left solitary in consequence, though with the prospect of being obliged to add to her resources by taking a few of the children of the town as day-pupils. her claim to take her place in the intellectual circle of the burgh was soon recognised. i found that, misled by the extreme youthfulness of her appearance, and a marked juvenility of manner, i had greatly mistaken the young lady. that she should be accomplished in the ordinary sense of the term--that she should draw, play, and sing well--would be what i should have expected; but i was not prepared to find that, mere girl as she seemed, she should have a decided turn, not for the lighter, but for the severer walks of literature, and should have already acquired the ability of giving expression to her thoughts in a style formed on the best english models, and not in the least like that of a young lady. the original shyness wore away, and we became great friends. i was nearly ten years her senior, and had read a great many more books than she; and, finding me a sort of dictionary of fact, ready of access, and with explanatory notes attached, that became long or short just as she pleased to draw them out by her queries, she had, in the course of her amateur studies, frequent occasion to consult me. there were, she saw, several ladies of her acquaintance, who used occasionally to converse with me in the churchyard; but in order to make assurance doubly sure respecting the perfect propriety of such a proceeding on her part, she took the laudable precaution of stating the case to her mother's landlord, a thoroughly sensible man, one of the magistrates of the burgh, and an elder of the kirk; and he at once certified that there was no lady of the place who might not converse, without remark, as often and as long as she pleased with me. and so, fully justified, both by the example of her friends--all very judicious women, some of them only a few years older than herself--and by the deliberate judgment of a very sensible man, the magistrate and elder--my young lady friend learned to visit me in the churchyard, just like the other ladies; and, latterly at least, considerably oftener than any of them. we used to converse on all manner of subjects connected with the _belles-lettres_ and the philosophy of mind, with, so far as i can at present remember, only one marked exception. on that mysterious affection which sometimes springs up between persons of the opposite sexes when thrown much together--though occasionally discussed by the metaphysicians, and much sung by the poets--we by no chance ever touched. love formed the one solitary subject which, from some curious contingency, invariably escaped us. and yet, latterly at least, i had begun to think about it a good deal. nature had not fashioned me one of the sort of people who fall in love at first sight. i had even made up my mind to live a bachelor life, without being very much impressed by the magnitude of the sacrifice; but i daresay it did mean something, that in my solitary walks for the preceding fourteen or fifteen years, a female companion often walked in fancy by my side, with whom i exchanged many a thought, and gave expression to many a feeling, and to whom i pointed out many a beauty in the landscape, and communicated many a curious fact, and whose understanding was as vigorous as her taste was faultless and her feelings exquisite. one of the english essayists--the elder moore--has drawn a very perfect personage of this airy character (not, however, of the softer, but of the masculine sex), under the name of the "maid's husband;" and described him as one of the most formidable rivals that the ordinary lover of flesh and blood can possibly encounter. my day-dream lady--a person that may be termed with equal propriety the "bachelor's wife,"--has not been so distinctly recognised; but she occupies a large place in our literature, as the mistress of all the poets who ever wrote on love without actually experiencing it, from the days of cowley down to those of henry kirke white; and her presence serves always to intimate a heart capable of occupation, but still unoccupied. i find the bachelor's wife delicately drawn in one the posthumous poems of poor alexander bethune, as a "fair being"--the frequent subject of his day-dreams-- "whose soft voice should be the sweetest music to his ear, awakening all the chords of harmony; whose eye should speak a language to his soul, more eloquent than aught which greece or rome could boast of in its best and happiest days; whose smile should be his rich reward for toil; whose pure transparent cheek, when press'd to his, should calm the fever of his troubled thoughts, and woo his spirit to those fields elysian-- the paradise which strong affection guards." it may be always predicated of these bachelors' wives, that they never closely resemble in their lineaments any living woman: poor bethune's would not have exhibited a single feature of any of his fair neighbours, the lasses of upper rankeillour or newburgh. were the case otherwise, the dream maiden would be greatly in danger of being displaced by the real one whom she resembled; and it was a most significant event, which, notwithstanding my inexperience, i learned by and bye to understand, that about this time my old companion, the "bachelor's wife," utterly forsook me, and that a vision of my young friend took her place. i can honestly aver, that i entertained not a single hope that the feeling should be mutual. on whatever other head my vanity may have flattered me, it certainly never did so on the score of personal appearance. my personal strength was, i knew, considerably above the average of that of my fellows, and at this time my activity also; but i was perfectly conscious that, on the other hand, my good looks rather fell below than rose above the medial line. and so, while i suspected, as i well might, that, as in the famous fairy story, "beauty" had made a conquest of the "beast," i had not the most distant expectation that the "beast" would, in turn, make a conquest of "beauty." my young friend had, i knew, several admirers--men who were younger and dressed better, and who, as they had all chosen the liberal professions, had fairer prospects than i; and as for the item of good looks, had she set her affections on even the least likely of them, i could have addressed him, with perfect sincerity, in the words of the old ballad:-- "nae wonder, nae wonder, gil morrice, my lady lo'es ye weel: the fairest part o' my body is blacker than thy heel." strange to say, however, much about the time that i made my discovery, my young friend succeeded in making a discovery also;--the maid's husband shared on her part the same fate as the bachelor's wife did on mine; and her visits to the churchyard suddenly ceased. a twelvemonth had passed ere we succeeded in finding all this out; but the young lady's mother had seen the danger somewhat earlier; and deeming, as was quite right and proper, an operative mason no very fitting mate for her daughter, my opportunities of meeting my friend at _conversazione_ or tea-party had become few. i, however, took my usual evening walk through the woods of the hill; and as my friend's avocations set her free at the same delightful hour, and as she also was a walker on the hill, we did sometimes meet, and witness together, from amid the deeper solitudes of its bosky slopes, the sun sinking behind the distant ben wevis. these were very happy evenings; the hour we passed together always seemed exceedingly short; but, to make amends for its briefness, there were at length few working days in the milder season of which it did not form the terminal one;--from the circumstance, of course, that the similarity of our tastes for natural scenery led us always into the same lonely walks about the same delicious sun-set hour. for months together, even during this second stage of our friendship, there was one interesting subject on which we never talked. at length, however, we came to a mutual understanding. it was settled that we should remain for three years more in scotland on the existing terms; and if during that time there should open to me no suitable field of exertion at home, we should then quit the country for america, and share together in a strange land whatever fate might be in store for us. my young friend was considerably more sanguine than i. i had laid faithfully before her those defects of character which rendered me a rather inefficient man-at-arms for contending in my own behalf in the battle of life. inured to labour, and to the hardships of the bothie and the barrack, i believed that in the backwoods, where i would have to lift my axe on great trees, i might get on with my clearing and my crops like most of my neighbours; but then the backwoods would, i feared, be no place for her; and as for effectually pushing my way in the long-peopled portions of the united states, among one of the most vigorous and energetic races in the world, i could not see that i was in the least fitted for that. she, however, thought otherwise. the tender passion is always a strangely exaggerative one. lodged in the male mind, it gives to the object on which it rests all that is excellent in woman, and in the female mind imparts to its object all that is noble in man; and my friend had come to regard me as fitted by nature either to head an army or lead a college, and to deem it one of the weaknesses of my character, that i myself could not take an equally favourable view. there was, however, one profession of which, measuring myself as carefully as i could, i deemed myself capable: i saw men whom i regarded as not my superiors in natural talent, and even possessed of no greater command of the pen, occupying respectable places in the periodical literature of the day, as the editors of scotch newspapers, provincial, and even metropolitan, and deriving from their labours incomes of from one to three hundred pounds per annum; and were my abilities, such as they were, to be fairly set by sample before the public, and so brought into the literary market, they might, i thought, possibly lead to my engagement as a newspaper editor. and so, as a first step in the process, i resolved on publishing my volume of traditional history--a work on which i had bestowed considerable care, and which, regarded as a specimen of what i could do as a _littérateur_, would, i believed, show not inadequately my ability of treating at least those lighter subjects with which newspaper editors are occasionally called on to deal. nearly two of the three twelvemonths passed by, however, and i was still an operative mason. with all my solicitude, i could not give myself heartily to seek work of the kind which i saw newspaper editors had at that time to do. it might be quite well enough, i thought, for the lawyer to be a special pleader. with special pleadings equally extreme on the opposite sides of a case, and a qualified judge to hold the balance between, the cause of truth and justice might be even more thoroughly served than if the antagonist agents were to set themselves to be as impartial and equal-handed as the magistrate himself. but i could not extend the same tolerance to the special pleading of the newspaper editor. i saw that, to many of the readers of his paper, the editor did not hold the place of a law-agent, but of a judge: it was his part to submit to them, therefore, not ingenious pleadings, but, to the best of his judgment, honest decisions. and not only did no place present itself for me in the editorial field, but i really could see no place in it that, with the views which i entertained on this head, i would not scruple to occupy. i saw no party cause for which i could honestly plead. my ecclesiastical friends had, with a few exceptions, cast themselves into the conservative ranks; and there i could not follow them. the liberals, on the other hand, being in office at the time, had become at least as like their old opponents as their former selves, and i could by no means defend all that _they_ were doing. in radicalism i had no faith; and chartism--with my recollection of the kind of treatment which i had received from the workmen of the south still strongly impressed on my mind--i thoroughly detested. and so i began seriously to think of the backwoods of america. but there was another destiny in store for me. my native town, up till this time, though a place of considerable trade, was unfurnished with a branch bank; but on the representation of some of its more extensive traders, and of the proprietors of the neighbouring lands, the commercial bank of scotland had agreed to make it the scene of one of its agencies, and arranged with a sagacious and successful merchant and shipowner of the place to act as its agent. it had fixed, too, on a young man as its accountant, at the suggestion of a neighbouring proprietor; and i heard of the projected bank simply as a piece of news of interest to the town and its neighbourhood, but, of course, without special bearing on any concern of mine. receiving, however, one winter morning, an invitation to breakfast with the future agent--mr. ross--i was not a little surprised, after we had taken a quiet cup of tea together, and beaten over half-a-dozen several subjects, to be offered by him the accountantship of the branch bank. after a pause of a full half-minute, i said that the walk was one in which i had no experience whatever--that even the little knowledge of figures which i had acquired at school had been suffered to fade and get dim in my mind from want of practice--and that i feared i would make but a very indifferent accountant. i shall undertake for you, said mr. ross, and do my best to assist you. all you have to do at present is just to signify your acceptance of the offer made. i referred to the young man who, i understood, had been already nominated accountant. mr. ross stated that, being wholly a stranger to him, and as the office was one of great trust, he had, as the responsible party, sought the security of a guarantee, which the gentleman who had recommended the young man declined to give; and so his recommendation had fallen to the ground. "but _i_ can give you no guarantee," i said. "from you," rejoined mr. ross, "none shall ever be asked." and such was one of the more special _providences_ of my life; for why should i give it a humbler name? in a few days after, i had taken leave of my young friend in good hope, and was tossing in an old and somewhat crazy coasting vessel, on my way to the parent bank at edinburgh, to receive there the instructions necessary to the branch accountant. i had wrought as an operative mason, including my term of apprenticeship, for fifteen years--no inconsiderable portion of the more active part of a man's life; but the time was not altogether lost. i enjoyed in these years fully the average amount of happiness, and learned to know more of the scottish people than is generally known. let me add--for it seems to be very much the fashion of the time to draw dolorous pictures of the condition of the labouring classes--that from the close of the first year in which i wrought as a journeyman up till i took final leave of the mallet and chisel, i never knew what it was to want a shilling; that my two uncles, my grandfather, and the mason with whom i served my apprenticeship--all working men--had had a similar experience; and that it was the experience of my father also. i cannot doubt that deserving mechanics may, in exceptional cases, be exposed to want; but i can as little doubt that the cases _are_ exceptional, and that much of the suffering of the class is a consequence either of improvidence on the part of the competently skilled, or of a course of trifling during the term of apprenticeship--quite as common as trifling at school--that always lands those who indulge in it in the hapless position of the inferior workman. i trust i may further add, that i was an honest mechanic. it was one of the maxims of uncle james, that as the jews, restricted by law to their forty stripes, always fell short of the legal number by one, lest they should by any accident exceed it, so a working man, in order to balance any disturbing element of selfishness in his disposition, should bring his charges for work done, slightly but sensibly within what he deemed the proper mark, and so give, as he used to express himself, his "customers the cast of the baulk." i do think i acted up to the maxim; and that, without injuring my brother workmen by lowering their prices, i never yet charged an employer for a piece of work that, fairly measured and valued, would not be rated at a slightly higher sum than that at which it stood in my account. i had quitted cromarty for the south late in november, and landed at leith on a bleak december morning, just in time to escape a tremendous storm of wind and rain from the west, which, had it caught the smack in which i sailed on the firth, would have driven us all back to fraserburgh, and, as the vessel was hardly sea-worthy at the time, perhaps a great deal further. the passage had been stormy; and a very noble, but rather unsocial fellow-passenger--a fine specimen of the golden eagle--had been sea-sick, and evidently very uncomfortable, for the greater part of the way. the eagle must have been accustomed to motion a great deal more rapid than that of the vessel, but it was motion of a different kind; and so he fared as persons do who never feel a qualm when hurried along a railway at the rate of forty miles an hour, but who yet get very squeamish in a tossing boat, that creeps through a rough sea at a speed not exceeding, in the same period of time, from four to five knots. the day preceding the storm was leaden-hued and sombre, and so calm, that though the little wind there was blew the right way, it carried us on, from the first light of morning, when we found ourselves abreast of the bass, to only near inchkeith; for when night fell, we saw the may light twinkling dimly far astern, and that of the inch rising bright and high right a-head. i spent the greater part of the day on deck, marking, as they came into view, the various objects--hill, and island, and seaport town, of which i had lost sight nearly ten years before; feeling the while, not without some craven shrinkings, that having got to the end, in the journey of life, of one very definite stage, with its peculiar scenery and sets of objects, i was just on the eve of entering upon another stage, in which the scenery and objects would be all unfamiliar and new. i was now two years turned of thirty; and though i could not hold that any very great amount of natural endowment was essentially necessary to the bank accountant, i knew that most men turned of thirty might in vain attempt acquiring the ability even of heading a pin with the necessary adroitness, and that i might fail, on the same principle, to pass muster as an accountant. i determined, however, obstinately to set myself to acquire, whatever might be the result; and entered edinburgh in something like spirits on the strength of the resolution. i had transmitted the manuscript of my legendary work, several months before, to sir thomas dick lauder; and as he was now on terms, in its behalf, with mr. adam black, the well-known publisher, i took the liberty of waiting on him, to see how the negotiation was speeding. he received me with great kindness; hospitably urged that i should live with him, so long as i resided in edinburgh, in his noble mansion, the grange house; and, as an inducement, introduced me to his library, full charged with the best editions of the best authors, and enriched with many a rare volume and curious manuscript. "here," he said, "robertson the historian penned his last work--the _disquisition_; and here," opening the door of an adjoining room, "he died." i, of course, declined the invitation. the grange house, with its books, and its pictures, and its hospitable master, so rich in anecdote, and so full of the literary sympathies, would have been no place for a poor pupil-accountant, too sure that he was to be stupid, but not the less determined on being busy. besides, on calling immediately after at the bank, i found that i would have to quit edinburgh on the morrow for some country agency, in which i might be initiated into the system of book-keeping proper to a branch bank and where the business transacted would be of a kind similar to what might be expected in cromarty. sir thomas, however, kindly got mr. black to meet me at dinner; and, in the course of the evening, that enterprising bookseller agreed to undertake the publication of my work, on terms which the nameless author of a volume somewhat local in its character, and very local in its name, might well regard as liberal. linlithgow was the place fixed on by the parent bank as the scene of my initiation into the mysteries of branch banking; and, taking my passage in one of the track-boats which at that time plied on the canal between edinburgh and glasgow, i reached the fine old burgh as the brief winter day was coming to a close, and was seated next morning at my desk, not a hundred yards from the spot on which hamilton of bothwellhaugh had taken his stand when he shot the good regent. i was, as i had anticipated, very stupid; and must have looked, i suppose, even more obtuse than i actually was: for my temporary superior the agent, having gone to edinburgh a few days after my arrival, gave expression, in the head bank, to the conviction that it would be in vain attempting making "yon man" an accountant. altogether deficient in the cleverness that can promptly master isolated details, when in ignorance of their bearing on the general scheme to which they belong, i could literally do nothing until i had got a hold of the system; which, locked up in the ponderous tomes of the agency, for some little time eluded my grasp. at length, however, it gradually unrolled itself before me in all its nice proportions, as one of perhaps the completest forms of "book-keeping" which the wit of man has yet devised; and i then found that the details which, when i had approached them as if from the outside, had repulsed and beaten me back, could, like the outworks of a fortress, be commanded from the centre with the utmost ease. just as i had reached this stage, the regular accountant of the branch was called away to an appointment in one of the joint stock banks of england; and the agent, again going into edinburgh on business, left me for the greater part of a day in direction of the agency. little more than a fortnight had elapsed since he had given his unfavourable verdict; and he was now asked how, in the absence of the accountant, he could have got away from his charge. he had left _me_ in the office, he said. "what! the _incompetent_?" "o, that," he replied, "is all a mistake; the incompetent has already mastered our system." the mechanical ability, however, came but slowly; and i never acquired the facility, in running up columns of summations, of the early-taught accountant; though, making up by diligence what i wanted in speed, i found, after my first few weeks of labour in linlithgow, that i could give as of old an occasional hour to literature and geology. the proof-sheets of my book began to drop in upon me, demanding revision; and to a quarry in the neighbourhood of the town, rich in the organisms of the mountain limestone, and overflown by a bed of basalt so regularly columnar, that one of the legends of the district attributed its formation to the "ancient pechts," i was able to devote, not without profit, the evenings of several saturdays. i formed, at this time, my first acquaintance with the palæozoic shells, as they occur in the rock--an acquaintance which has since been extended in some measure through the silurian deposits, upper and lower; and these shells, though marked, in the immensely extended ages of the division to which they belong, by specific, and even generic variety, i have found exhibiting throughout a unique family type or pattern, as entirely different from the family type of the secondary shells as both are different from the family types of the tertiary and the existing ones. each of the three great periods of creation had its own peculiar fashion; and after having acquainted myself with the fashions of the second and third periods, i was now peculiarly interested in the acquaintance which i was enabled to commence with that of the first and earliest also. i found, too, in a bed of trap beside the edinburgh road, scarce half a mile to the east of the town, numerous pieces of carbonized lignite, which still retained the woody structure--probably the broken remains of some forest of the carboniferous period, enveloped in some ancient lava bed, that had rolled over its shrubs and trees, annihilating all save the fragments of charcoal, which, locked up in its viscid recesses, had resisted the agency that dissipated the more exposed embers into gas. i had found, in like manner, when residing at conon-side and inverness, fragments of charcoal locked up in the glassy vesicular stone of the old vitrified forts of craig phadrig and knock farril, and existing as the sole representatives of the vast masses of fuel which must have been employed in fusing the ponderous walls of these unique fortalices. and i was now interested to find exactly the same phenomena among the _vitrified_ rocks of the coal measures. brief as the days were, i had always a twilight hour to myself in linlithgow; and as the evenings were fine for the season, the old royal park of the place, with its noble church, its massive palace, and its sweet lake, still mottled by the hereditary swans whose progenitors had sailed over its waters in the days when james iv. worshipped in the spectre aisle, formed a delightful place of retreat, little frequented by the inhabitants of the town, but only all the more my own in consequence; and in which i used to feel the fatigue of the day's figuring and calculation drop away into the cool breezy air, like cobwebs from an unfolded banner, as i climbed among the ruins, or sauntered along the grassy shores of the loch. my stay at linlithgow was somewhat prolonged, by the removal, first of the accountant of the branch, and then of its agent, who was called south to undertake the management of a newly-erected english bank; but i lost nothing by the delay. an admirable man of business, one of the officials of the parent bank in edinburgh (now its agent in kirkcaldy, and recently provost of the place), was sent temporarily to conduct the business of the agency; and i saw, under him, how a comparative stranger arrived at his conclusions respecting the standing and solvency of the various customers with whom, in behalf of the parent institute, he was called on to deal. and, finally, my brief term of apprenticeship expired--about two months in all--i returned to cromarty; and, as the opening of the agency there waited only my arrival, straightway commenced my new course as an accountant. my minister, when he first saw me seated at the desk, pronounced me "at length fairly caught;" and i must confess i did feel as if my latter days were destined to differ from my earlier ones, well nigh as much as those of peter of old, who, when he was "young, girded himself, and walked whither he would, but who, when old, was girded by others, and carried whither he would not." two long years had to pass from this time ere my young friend and i could be united--for such were the terms on which we had to secure the consent of her mother; but, with our union in the vista, we could meet more freely than before; and the time passed not unpleasantly away. for the first six months of my new employment, i found myself unable to make my old use of the leisure hours which, i found, i could still command. there was nothing very intellectual, in the higher sense of the term, in recording the bank's transactions, or in summing up columns of figures, or in doing business over the counter; and yet the fatigue induced was a fatigue, not of sinew and muscle, but of nerve and brain, which, if it did not quite disqualify me for my former intellectual amusements, at least greatly disinclined me towards them, and rendered me a considerably more indolent sort of person than either before or since. it is asserted by artists of discriminating eye, that the human hand bears an expression stamped upon it by the general character, as surely as the human face; and i certainly used to be struck, during this transition period, by the relaxed and idle expression that had on the sudden been assumed by mine. and the slackened hands represented, i too surely felt, a slackened mind. the unintellectual toils of the labouring man have been occasionally represented as less favourable to mental cultivation than the semi-intellectual employments of that class immediately above him, to which our clerks, shopmen, and humbler accountants belong; but it will be found that exactly the reverse is the case, and that, though a certain conventional gentility of manner and appearance on the side of the somewhat higher class may serve to conceal the fact, it is on the part of the labouring man that the real advantage lies. the mercantile accountant or law-clerk, bent over his desk, his faculties concentrated on his columns of figures, or on the pages which he has been carefully engrossing, and unable to proceed one step in his work without devoting to it all his attention, is in greatly less favourable circumstances than the ploughman or operative mechanic, whose mind is free though his body labours, and who thus finds, in the very rudeness of his employments, a compensation for their humble and laborious character. and it will be found that the humbler of the two classes is much more largely represented in our literature than the class by one degree less humble. ranged against the poor clerk of nottingham, henry kirke white, and the still more hapless edinburgh engrossing clerk, robert fergusson, with a very few others, we find in our literature a numerous and vigorous phalanx, composed of men such as the ayrshire ploughman, the ettrick shepherd, the fifeshire foresters, the sailors dampier and falconer--bunyan, bloomfield, ramsay, tannahill, alexander wilson, john clare, allan cunningham, and ebenezer elliot. and i was taught at this time to recognise the simple principle on which the greater advantages lie on the side of the humbler class. gradually, however, as i became more inured to sedentary life, my mind recovered its spring, and my old ability returned of employing my leisure hours, as before, in intellectual exertion. meanwhile my legendary volume issued from the press, and was, with a few exceptions, very favourably received by the critics. leigh hunt gave it a kind and genial notice in his _journal_; it was characterized by robert chambers not less favourably in _his_; and dr. hetherington, the future historian of the church of scotland and of the westminster assembly of divines--at that time a licentiate of the church--made it the subject of an elaborate and very friendly critique in the _presbyterian review_. nor was i less gratified by the terms in which it was spoken of by the late baron hume, the nephew and residuary legatee of the historian--himself very much a critic of the old school--in a note to a north-country friend. he described it as a work "written in an english style which" he "had begun to regard as one of the lost arts." but it attained to no great popularity. for being popular, its subjects were too local, and its treatment of them perhaps too quiet. my publishers tell me, however, that it not only continues to sell, but moves off considerably better in its later editions that it did on its first appearance. the branch bank furnished me with an entirely new and curious field of observation, and formed a very admirable school. for the cultivation of a shrewd common sense, a bank office is one of perhaps the best schools in the world. mere cleverness serves often only to befool its possessor. he gets entangled among his own ingenuities, and is caught as in a net. but ingenuities, plausibilities, special pleadings, all that make the stump-orator great, must be brushed aside by the banker. the question with him comes always to be a sternly naked one:--is, or is not, mr. ---- a person fit to be trusted with the bank's money? is his sense of monetary obligations nice, or obtuse? is his judgment good, or the contrary? are his speculations sound, or precarious? what are his resources?--what his liabilities? is he facile in lending the use of his name? does he float on wind bills, as boys swim on bladders? or is his paper representative of only real business transactions? such are the topics which, in the recesses of his own mind, the banker is called on to discuss; and he must discuss them, not merely plausibly or ingeniously, but solidly and truly; seeing that error, however illustrated or adorned, or however capable of being brilliantly defended in speech or pamphlet, is sure always with him to take the form of pecuniary loss. my superior in the agency--mr. ross, a good and honourable-minded man, of sense and experience--was admirably fitted for calculations of this kind; and i learned, both in his behalf, and from the pleasure which i derived from the exercise, to take no little interest in them also. it was agreeable to mark the moral effects of a well-conducted agency such as his. however humbly honesty and good sense may be rated in the great world generally, they always, when united, bear premium in a judiciously managed bank office. it was interesting enough, too, to see quiet silent men, like "honest farmer flamburgh," getting wealthy, mainly because, though void of display, they were not wanting in integrity and judgment; and clever unscrupulous fellows, like "ephraim jenkinson," who "spoke to good purpose," becoming poor, very much because, with all their smartness, they lacked sense and principle. it was worthy of being noted, too, that in looking around from my peculiar point of view on the agricultural classes, i found the farmers, on really good farms, usually thriving, if not themselves in fault, however high their rents; and that, on the other hand, farmers on sterile farms were _not_ thriving, however moderate the demands of the landlord. it was more melancholy, but not less instructive, to learn, from authorities whose evidence could not be questioned--bills paid by small instalments, or lying under protest--that the small-farm system, so excellent in a past age, was getting rather unsuited for the energetic competition of the present one; and that the _small_ farmers--a comparatively comfortable class some sixty or eighty years before, who used to give dowries to their daughters, and leave well-stocked farms to their sons--were falling into straitened circumstances, and becoming, however respectable elsewhere, not very good men in the bank. it was interesting, too, to mark the character and capabilities of the various branches of trade carried on in the place--how the business of its shopkeepers fell always into a very few hands, leaving to the greater number, possessed, apparently, of the same advantages as their thriving compeers, only a mere show of custom--how precarious in its nature the fishing trade always is, especially the herring fishery, not more from the uncertainty of the fishings themselves, than from the fluctuations of the markets--and how in the pork trade of the place a judicious use of the bank's money enabled the curers to trade virtually on a doubled capital, and to realize, with the deduction of the bank discounts, doubled profits. in a few months my acquaintance with the character and circumstances of the business men of the district became tolerably extensive, and essentially correct; and on two several occasions, when my superior left me for a time to conduct the entire business of the agency, i was fortunate enough not to discount for him a single bad bill. the implicit confidence reposed in me by so good and sagacious a man was certainly quite enough of itself to set me on my metal. there was, however, at least one item in my calculations in which i almost always found myself incorrect: i found i could predict every bankruptcy in the district; but i usually fell short from ten to eighteen months of the period in which the event actually took place. i could pretty nearly determine the time when the difficulties and entanglements which i saw _ought_ to have produced their proper effects, and landed in failure; but i missed taking into account the desperate efforts which men of energetic temperament make in such circumstances, and which, to the signal injury of their friends and the loss of their creditors, succeed usually in staving off the catastrophe for a season. in short, the school of the branch bank was a very admirable school; and i profited so much by its teachings, that when questions connected with banking are forced on the notice of the public, and my brother editors have to apply for articles on the subject to literary bankers, i find i can write my banking articles for myself. the seasons passed by; the two years of probation came to a close, like all that had gone before; and after a long, and, in its earlier stages, anxious courtship of in all five years, i received from the hand of mr. ross that of my young friend, in her mother's house, and was united to her by my minister, mr. stewart. and then, setting out, immediately after the ceremony, for the southern side of the moray firth, we spent two happy days together in elgin; and, under the guidance of one of the most respected citizens of the place, my kind friend mr. isaac forsyth, visited the more interesting objects connected with the town or its neighbourhood. he introduced us to the elgin cathedral;--to the veritable john shanks, the eccentric keeper of the building, who could never hear of the wolf of badenoch, who had burnt it four hundred years before, without flying into a rage, and becoming what the dead man would have deemed libellous;--to the font, too, under a dripping vault of ribbed stone, in which an insane mother used to sing to sleep the poor infant, who, afterwards becoming lieutenant-general anderson, built for poor paupers like his mother, and poor children such as he himself had once been, the princely institution which bears his name. and then, after passing from the stone font to the institution itself, with its happy children, and its very unhappy old men and women, mr. forsyth conveyed us to the pastoral, semi-highland valley of pluscardine, with its beautiful wood-embosomed priory--one of perhaps the finest and most symmetrical specimens of the unornamented gothic of the times of alexander ii. to be seen anywhere in scotland. finally, after passing a delightful evening at his hospitable board, and meeting, among other guests, my friend mr. patrick duff--the author of the "geology of moray"--i returned with my young wife to cromarty, and found her mother, mr. ross, mr. stewart, and a party of friends, waiting for us in the house which my father had built for himself forty years before, but which it had been his destiny never to inhabit. it formed our home for the three following years. the subjoined verses--prose, i suspect, rather than poetry, for the mood in which they were written was too earnest a one to be imaginative--i introduce, as representative of my feelings at this time: they were written previous to my marriage, on one of the blank pages of a pocket-bible, with which i presented my future wife:-- to lydia. lydia, since ill by sordid gift were love like mine express'd, take heaven's best boon, this sacred book, from him who loves thee best. love strong as that i bear to thee were sure unaptly told by dying flowers, or lifeless gems, or soul-ensnaring gold. i know 'twas he who formed this heart who seeks this heart to guide; for why?--he bids me love thee more than all on earth beside.[ ] yes, lydia, bids me cleave to thee, as long this heart has cleaved: would, dearest, that his other laws were half so well received! full many a change, my only love, on human life attends; and at the cold sepulchral stone th' uncertain vista ends. how best to bear each various change, should weal or woe befall, to love, live, die, this sacred book, lydia, it tells us all. oh, much-beloved, our coming day to us is all unknown, but sure we stand a broader mark than they who stand alone. _one_ knows it all: not his an eye, like ours, obscured and dim; and knowing us, he gives this book, that we may know of him. his words, my love, are gracious words, and gracious thoughts express: he cares e'en for each little bird that wings the blue abyss. of coming wants and woes he thought, ere want or woe began; and took to him a human heart. that he might feel for man. then oh! my first, my only love, the kindliest, dearest, best! on him may all our hopes repose,-- on him our wishes rest. his be the future's doubtful day, let joy or grief befall: in life or death, in weal or woe, our god, our guide, our all. footnotes: [ ] professor pillans. [ ] "for this cause shall a man leave father and mother, and shall cleave to his wife; and they twain shall be one flesh." chapter xxiv. "life is a drama of a few brief acts; the actors shift, the scene is often changed, pauses and revolutions intervene, the mind is set to many a varied tune. and jars and plays in harmony by turns." alexander bethune. though my wife continued, after our marriage, to teach a few pupils, the united earnings of the household did not much exceed a hundred pounds per annum--not quite so large a sum as i had used to think it a few years before; and so i set myself to try whether i could not turn my leisure hours to some account, by writing for the periodicals. my old inability of pressing for work continued to be as embarrassing as ever, and, save for a chance engagement of no very promising kind, which presented itself to me unsolicited about this time, i might have failed in procuring the employment which i sought. an ingenious self-taught mechanic--the late mr. john mackay wilson of berwick-on-tweed--after making good his upward way from his original place at the compositor's frame, to the editorship of a provincial paper, started, in the beginning of , a weekly periodical, consisting of "border tales," which, as he possessed the story-telling ability, met with considerable success. he did not live, however, to complete the first yearly volume; the forty-ninth weekly number intimated his death; but as the publication had been a not unprofitable one, the publisher resolved on carrying it on; and it was stated in a brief notice, which embodied a few particulars of mr. wilson's biography, that, his materials being unexhausted, "tales yet untold lay in reserve, to keep alive his memory." and in the name of wilson the publication was kept up for, i believe, five years. it reckoned among its contributors the two bethunes, john and alexander, and the late professor gillespie of st. andrews, with several other writers, none of whom seem to have been indebted to any original matter collected by its first editor; and i, who, at the publisher's request, wrote for it, during the first year of my marriage, tales enough to fill an ordinary volume, had certainly to provide all my materials for myself. the whole brought me about twenty-five pounds--a considerable addition to the previous hundred and odds of the household, but, for the work done, as inadequate a remuneration as ever poor writer got in the days of grub street. my tales, however, though an english critic did me the honour of selecting one of them as the best in the monthly part in which it appeared, were not of the highest order: it took a great deal of writing to earn the three guineas, which were the stipulated wages for filling a weekly number; and though poor wilson may have been a fine enough fellow in his way, one had no great encouragement to do one's very best, in order to "keep alive his memory." in all such matters, according to sir walter scott and the old proverb, "every herring should hang by its own head." i can show, however, that at least one of my contributions _did_ gain wilson some little credit. in the perilous attempt to bring out, in the dramatic form, the characters of two of our national poets--burns and fergusson--i wrote for the "tales" a series of "recollections," drawn ostensibly from the memory of one who had been personally acquainted with them both, but in reality based on my own conceptions of the men, as exhibited in their lives and writings. and in an elaborate life of fergusson, lately published, i find a borrowed extract from my contribution, and an approving reference to the whole, coupled with a piece of information entirely new to me. "these recollections," says the biographer, "are truly interesting and touching, _and were the result of various communications made to mr. wilson_, whose pains-taking researches i have had frequent occasion to verify in the course of my own." alas, no! poor wilson was more than a twelvemonth in his grave ere the idea of producing these "recollections" first struck the writer--a person to whom no communications on the subject were ever made by any one, and who, unassisted save by one of the biographies of the poet--that in chambers' "lives of illustrious scotsmen,"--wrote full two hundred miles from the scene of his sad and brief career. the same individual who, in mr. wilson's behalf, is so complimentary to my "pains-taking research," is, i find, very severe on one of fergusson's previous biographers--the scholarly dr. irving, author of the life of buchanan, and the lives of the older scottish poets--a gentleman who, whatever his estimate of the poor poet may have been, would have spared no labour in elucidating the various incidents which composed his history. the man of research is roughly treated, and a compliment awarded to the diligence of the man of none. but it is always thus with fame. "some she disgraced, and some with honours crown'd; unlike successes equal merits found: so her blind sister, fickle fortune, reigns. and, undiscerning, scatters crowns and chains." in the memoir of john bethune by his brother alexander, the reader is told that he was much depressed and disappointed, about a twelvemonth or so previous to his decease, by the rejection of several of his stories in succession, which were returned to him, "with an editor's sentence of death passed upon them." i know not whether it was by the editor of the "tales of the borders" that sentence in the case was passed; but i know he sentenced some of mine, which were, i daresay, not very good, though well-nigh equal, i thought, to most of his own instead, however, of yielding to depression, like poor bethune, i simply resolved to write for him no more; and straightway made an offer of my services to mr. robert chambers, by whom they were accepted; and during the two following years i occasionally contributed to his _journal_, on greatly more liberal terms than those on which i had laboured for the other periodical, and with my name attached to my several articles. i must be permitted to avail myself of the present opportunity of acknowledging the kindness of mr. chambers. there is perhaps no other writer of the present day who has done so much to encourage struggling talent as this gentleman. i have for many years observed that publications, however obscure, in which he finds aught really praiseworthy, are secure always of getting, in his widely-circulated periodical, a kind approving word--that his criticisms invariably bear the stamp of a benevolent nature, which experiences more of pleasure in the recognition of merit than in the detection of defect--that his kindness does not stop with these cheering notices, for he finds time, in the course of a very busy life, to write many a note of encouragement and advice to obscure men in whom he recognises a spirit superior to their condition--and that the compositions of writers of this meritorious class, when submitted to him editorially, rarely fail, if really suitable for his journal, to find a place in it, or to be remunerated on a scale that invariably bears reference to the value of the communications--not to the circumstances of their authors. i can scarce speak of my contributions to the periodicals at this time as forming any part of my education. i acquired, in their composition, a somewhat readier command of the pen than before; but they, of course, tended rather to the dissipation of previous stores than to the accumulation of new ones; nor did they give exercise to those higher faculties of mind which i deemed it most my interest to cultivate. my real education at the time was that in which i was gradually becoming initiated behind the bank-counter, as my experience of the business of the district extended; and that which i contrived to pick up in my leisure evenings along the shores. a rich ichthyolitic deposit of the old red sandstone lies, as i have already said, within less than half a mile of the town of cromarty; and when fatigued with my calculations in the bank, i used to find it delightful relaxation to lay open its fish by scores, and to study their peculiarities as exhibited in their various states of keeping, until i at length became able to determine their several genera and species from even the minutest fragments. the number of ichthyolites which that deposit of itself furnished--a patch little more than forty yards square--seemed altogether astonishing: it supplied me with specimens at almost every visit, for ten years together; nor, though, after i left cromarty for edinburgh, it was often explored by geologic tourists, and by a few cultivators of science in the place, was it wholly exhausted for ten years more. the ganoids of the second age of vertebrate existence must have congregated as thickly upon that spot in the times of the lower old red sandstone, as herrings ever do now, in their season, on the best fishing-banks of caithness or the moray firth. i was for some time greatly puzzled in my attempts to restore these ancient fishes, by the peculiarities of their organization. it was in vain i examined every species of fish caught by the fishermen of the place, from the dog-fish and the skate to the herring and the mackerel. i could find in our recent fishes no such scales of enamelled bone as those which had covered the _dipterians_ and the _celacanths_; and no such plate-encased animals as the various species of _coccosteus_ or _pterichthys_. on the other hand, with the exception of a double line of vertebral processes in the _coccosteus_, i could find in the ancient fishes no internal skeleton: they had apparently worn all their bones outside, where the crustaceans wear their shells, and were furnished inside with but frameworks of perishable cartilage. it seemed somewhat strange, too, that the geologists who occasionally came my way--some of them men of eminence--seemed to know even less about my old red fishes and their peculiarities of structure, than i did myself. i had represented the various species of the deposit simply by numerals, which not a few of the specimens of my collection still retain on their faded labels; and waited on until some one should come the way learned enough to substitute for my provisional figures words by which to designate them; but the necessary learning seemed wanting, and i at length came to find that i had got into a _terra incognita_ in the geological field, the greater portion of whose organisms were still unconnected with human language. they had no representatives among the vocables. i formed my first imperfect acquaintance with the recent ganoidal fishes in , from a perusal of the late dr. hibbert's paper on the deposit of burdiehouse, which i owed to the kindness of mr. george anderson. dr. hibbert, in illustrating the fishes of the coal measures, figured and briefly described the lepidosteus of the american rivers as a still surviving fish of the early type; but his description of the animal, though supplemented shortly after by that of dr. buckland in his bridgewater treatise, carried me but a little way. i saw that two of the old red genera--_osteolepis_ and _diplopterus_--resembled the american fish externally. it will be seen that the first-mentioned of these ancient ichthyolites bears a name compounded, though, in the reverse order, of exactly the same words. but while i found the skeleton of the lepidosteus described as remarkably hard and solid, i could detect in the _osteolepis_ and its kindred genus no trace of internal skeleton at all the cephalaspean genera, too--_coccosteus_ and _pterichthys_--greatly puzzled me: i could find no living analogues for them; and so, in my often-repeated attempts at restoration, i had to build them up plate by plate, as a child sets up its dissected map or picture bit by bit--every new specimen that turned up furnishing a key for some part previously unknown--until at length, after many an abortive effort, the creatures rose up before me in their strange, unwonted proportions, as they had lived, untold ages before, in the primæval seas. the extraordinary form of _pterichthys_ filled me with astonishment; and with its arched carpace and flat plastron restored before me, i leaped to the conclusion, that as the recent lepidosteus, with its ancient representatives of the old red sandstone, were sauroid fishes--strange connecting links between fishes and alligators--so the _pterichthys_ was a chelonian fish--a connecting link between the fish and the tortoise. a gurnard--insinuated so far through the shell of a small tortoise as to suffer its head to protrude from the anterior opening, furnished with oar-like paddles instead of pectoral fins, and with its caudal fin clipped to a point--would, i found, form no inadequate representative of this strangest of fishes. and when, some years after, i had the pleasure of introducing it to the notice of agassiz, i found that, with all his world-wide experience of its class, it was as much an object of wonder to him as it had been to myself. "it is impossible," we find him saying, in his great work, "to see aught more bizarre in all creation than the _pterichthyan_ genus: the same astonishment that cuvier felt in examining the plesiosaurus, i myself experienced, when mr. h. miller, the first discoverer of these fossils, showed me the specimens which he had detected in the old red sandstone of cromarty." and there were peculiarities about the _coccosteus_ that scarce less excited my wonder than the general form of the _pterichthys_, and which, when i first ventured to describe them, were regarded by the higher authorities in palæontology as mere blunders on the part of the observer. i have, however, since succeeded in demonstrating that, if blunders at all--which i greatly doubt, for nature makes very few--it was nature herself that was in error, not the observer. in this strange _coccostean_ genus, nature _did_ place a group of opposing teeth in each ramus of the lower jaw, just in the line of the symphysis--an arrangement unique, so far as is yet known, in the vertebrate division of creation, and which must have rendered the mouth of these creatures an extraordinary combination of the horizontal mouth proper to the vertebrata, and of the vertical mouth proper to the crustaceans. it was favourable to the integrity of my work of restoration, that the press was not waiting for me, and that when portions of the creatures on which i wrought were wanting, or plates turned up whose places i was unable to determine, i could lay aside my self-imposed task for the time, and only resume it when some new-found specimen supplied me with the materials requisite for carrying it on. and so the restorations which i completed in , and published in , were found, by our highest authorities in , after they had been set aside for nearly six years, to be essentially the true ones after all. i see, however, that one of the most fanciful and monstrous of all the interim restorations of _pterichthys_ given to the world--that made by mr. joseph dinkel in for the late dr. mantell, and published in the "medals of creation," has been reproduced in the recent illustrated edition of the "vestiges of creation." but the ingenious author of that work could scarce act prudently were he to stake the soundness of his hypothesis on the integrity of the restoration. for my own part, i consent, if it can be shown that the _pterichthys_ which once lived and moved on this ancient globe of ours ever either rose or sunk into the _pterichthys_ of mr. dinkel, freely and fully to confess, not only the possibility, but also the _actuality_, of the transmutation of both species and genera. i am first, however, prepared to demonstrate, before any competent jury of palæontologists in the world, that not a single plate or scale of mr. dinkel's restoration represents those of the fish which he professed to restore; that the same judgment applies equally to his restoration of _coccosteus_; and that, instead of reproducing in his figures the true forms of ancient cephalaspeans, he has merely given, instead, the likeness of things that never were "in the heaven above, or in the earth beneath, or in the waters under the earth." the place in the geologic scale, as certainly as the forms and characters, of these ancient fishes, had to be determined. mr. george anderson had informed me, as early as , that some of them were identical with the ichthyolites of the gamrie deposit; but then the place of the gamrie deposit was still to fix. it had been recently referred to the same geological horizon as the carboniferous limestone, and was regarded as lying unconformable to the old red sandstone of the district in which it occurs; but, wholly dissatisfied with the evidence adduced, i continued my search, and, though the process was a slow one, saw the position of the cromarty beds gradually approximating towards determination. it was not, however, until the autumn of that i got them fairly fixed down to the old red sandstone, and not until the winter of that i was able conclusively to demonstrate their place in the base of the system, little more than a hundred feet, and in one part not more than eighty feet, above the upper strata of the great conglomerate. i had often wished, during my explorations, to be able to extend my field of observation into the neighbouring counties, in order to determine whether i could not possess myself, at a distance, of the evidence which, for a time at least, i failed to find at home; but my daily engagements in the bank fixed me down to cromarty and its neighbourhood; and i found myself somewhat in the circumstances of a tolerably lively beetle stuck on a pin, that, though able, with a little exertion, to spin round its centre, is yet wholly unable to quit it. i acquired, however, at the close of , in the late dr. john malcolmson of madras, a noble auxiliary, who could expatiate freely over the regions virtually barred against me. he had been led to visit cromarty by a brief description of its geology, rather picturesque than scientific, which had appeared in my legendary volume; and after i had introduced him to its ichthyolitic beds on both sides of the hill and at eathie, and acquainted him with their character and organisms, he set himself to trace out the resembling deposits of the neighbouring shires of banff, moray, and nairn. and in little more than a fortnight he had detected the ichthyolites in numerous localities all over an old red sandstone tract, which extends from the primary districts of banff to near the field of culloden. the old red sandstone of the north, hitherto deemed so poor in fossils, he found--with the cromarty deposits as his key--teeming with organic remains. in the spring of , dr. malcolmson visited england and the continent, and introduced some of my cephalaspean fossils to the notice of agassiz, and some of the evidence which i had laid before him regarding their place in the scale, to mr. (now sir roderick) murchison. and i had the honour, in consequence, of corresponding with both these distinguished men; and the satisfaction of knowing, that by both, the fruit of my labours was deemed important. i observe that humboldt, in his "cosmos," specially refers to the judgment of agassiz on the extraordinary character of the new zoological link with which i had furnished him; and i find murchison, in his great work on the silurian system, published in , laying no little emphasis on the stratigraphical fact. after referring to the previously formed opinion that the gamrie deposit, with its ichthyolites, was not an old red one, he goes on to say--"on the other hand, i have recently been informed by dr. malcolmson, that mr. miller of cromarty (who has made some highly interesting discoveries near that place) pointed out to him nodules resembling those of gamrie, and containing similar fishes, in highly-inclined strata, which are interpolated in, and completely subordinate to, the great mass of old red sandstone of ross and cromarty. this important observation will, i trust, be soon communicated to the geological society, for it strengthens the inference of m. agassiz respecting the epoch during which the _cheiracanthus_ and _cheirolepis_ lived." all this will, i am afraid, appear tolerably weak to the reader, and somewhat more than tolerably tedious. let him remember, however, that the only merit to which i lay claim in the case is that of patient research--a merit in which whoever wills may rival or surpass me; and that this humble faculty of patience, when rightly directed, may lead to more extraordinary developments of idea than even genius itself. what i had been slowly deciphering were the _ideas_ of god as developed in the mechanism and framework of his creatures, during the second age of vertebrate existence; and one portion of my inquiries determined the date of these ideas, and another their character. many of the best sections of the sutors and the adjacent hills, with their associated deposits, cannot be examined without boat; and so i purchased for a few pounds a light little yawl, furnished with mast and sail, and that rowed four oars, to enable me to carry out my explorations. it made me free of the cromarty and moray firths for some six or eight miles from the town, and afforded me many a pleasant evening's excursion to the deep-sea caves and skerries, and the picturesque surf-wasted stacks of the granitic wall of rock which runs in the ben nevis line of elevation, from shadwick on the east to the scarfs crag on the west. i know not a richer tract for the geologist. independently of the interest that attaches to its sorely-contorted granitic gneiss--which seems, as murchison shrewdly remarks, to have been protruded through the sedimentary deposits in a solid state, as a fractured bone is sometimes protruded through the integuments--there occurs along the range three several deposits of the old red ichthyolites, and three several deposits of the lias, besides the sub-aqueous ones, with two insulated skerries, which i am inclined to regard as outliers of the oolite. these last occur in the form of half-tide rocks, very dangerous to the mariner, which lie a full half-mile from the shore, and can be visited with safety only at low water during dead calms, when no ground swell comes rolling in from the sea. i have set out as early as two o'clock in a fine summer morning for these skerries, and, after spending several hours upon them, have been seated at the bank desk before ten; but these were mornings of very hard work. it was the long saturday afternoons that were my favourite seasons of explorations; and when the weather was fine, my wife would often accompany me in these excursions; and we not unfrequently anchored our skiff in some rocky bay, or over some fishing bank, and, provided with rods and lines, caught, ere our return, a basket of rock-cod or coal-fish for supper, that always seemed of finer flavour than the fish supplied us in the market. these were happy holidays. shelley predicates of a day of exquisite beauty, that it would continue to "live like joy in memory." i do retain recollections of these evenings spent in my little skiff--recollections mingled with a well-remembered imagery of blue seas and purple hills, and a sun-lit town in the distance, and tall wood-crested precipices nearer at hand, which flung lengthened shadows across shore and sea--that not merely represent enjoyments which have been, but that, in certain moods of the mind, take the form of enjoyment still. they are favoured spots in the chequered retrospect of the past, on which the sunshine of memory falls more brightly than on most of the others. when thus employed, there broke out very unexpectedly, a second war with the liberal moderates of the town, in which, unwillingly rather than otherwise, i had ultimately to engage. the sacrament of the supper is celebrated in most of the parish churches of the north of scotland only once a year; and, as many of the congregations worship at that time in the open air, the summer and autumn seasons are usually selected for the "occasion," as best fitted for open-air meetings. as, however, the celebration is preceded and followed by week-day preachings, and as on one of these week-days--the thursday preceding the sacramental sabbath--no work is done, kirk-sessions usually avoid fixing their sacrament in a busy time, such as the time of harvest in the rural districts, or of the herring-fishing in the seaport towns; and as the parish of cromarty has both its rural population and its fishing one, the kirk-session of the place have to avoid both periods. and so the early part of july, ere the herring-fishing or the harvest comes on, is the time usually fixed upon for the cromarty sacrament. in this year, however ( ), it so chanced that the day appointed for the queen's coronation proved coincident with the sacramental thursday, and the liberal moderate party urged upon the session that the preparations for the sacrament should give way to the rejoicings for the coronation. we had not been much accustomed to rejoicings of the kind in the north since the good old times when respectable tory gentlemen used to show themselves drunk in public on the king's birthday, in order to demonstrate their loyalty: the coronation days of both george iv. and william iv. had passed off as quietly as sabbaths; and the session, holding that it might be quite as well for people to pray for their young queen at church, and then quietly drink her health when they got home, as to grow glorious in her behalf in taverns and tap-rooms, refused to alter their day. believing that, though essentially in the right, they were yet politically in the wrong, and that a plausible case might be made out against them by the newspaper press, i waited on my minister, and urged him to give way to the liberals, and have his preparation-day changed from thursday to friday. he seemed quite willing enough to act on the suggestion; nay, he had made a similar one, he told me, to his session; but the devout eldership, strong in the precedents of centuries, had declined to subordinate the religious services of the kirk to the wassail and merriment sanctioned by the state. and so they determined on keeping their day of sacramental preparation on the thursday, as their fathers had done. meanwhile, the liberals held what was very properly termed a public meeting, seeing that, though the public had failed to attend it, the public had been quite at liberty to do so, nay, had even been specially invited; and there appeared in the provincial newspapers a long report of its proceedings, including five speeches--all written by a legal gentleman--in which it was designated a meeting of the inhabitants of the town and parish of cromarty. the resolutions were, of course, of the most enthusiastically loyal character. there was not a member of the meeting who was not prepared to spend upon himself the last drop of his bottle of port in her majesty's behalf. thursday came--the thursday of the sacrament and of the coronation; and, with ninety-nine hundredths of the church-going portion of my townsfolk, i went to church as usual. the parochial resolutioners, amounting in all to ten, were, i can honestly avouch, scarce at all missed in a congregation of nearly as many hundreds. about mid-day, however, we could hear the muffled report of their carronades; and, shortly after the service was over, and we had returned to our homes, there passed through the streets a forlorn little group of individuals, that looked exceedingly like a press-gang, but was in reality intended for a procession. though joined by a proprietor from a neighbouring parish, a lawyer from a neighbouring burgh, a small coast-guard party, with its commanding officer, and two half-pay episcopalian officers besides, the number who walked, including boys, did not exceed twenty-five persons; and of these, as i have said, only ten were parishioners. the processionists had a noble dinner in the head inn of the place--merrier than even dinners of celebration usually are, as it was, of course, loyalty and public spirit to ignore the special claim upon the day asserted by the church; and the darkening evening saw a splendid bonfire blazing from the brae-head. and the liberal newspapers south and north taking part with the processionists, in many a paragraph and short leader, represented their frolic--for such it was, and a very foolish one--as a splendid triumph of the people of cromarty over presbyterial bigotry and clerical domination. nay, so bad did the case of my minister and his session appear, thus placed in opposition to at once the people and the queen, that the papers on the other side failed to take it up. a well-written letter on the subject by my wife, which fairly stated the facts, was refused admission into even the ecclesiastico-conservative journal, specially patronized, at the time, by the scottish church; and my minister's friends and brethren in the south could do little else than marvel at what they deemed his wondrous imprudence. i had anticipated, from the first, that his position was to be a bad one; but i ill liked to see him with his back to the wall. and though i had determined, on the rejection of my counsel, to take no part in the quarrel, i now resolved to try whether i could not render it evident that he was really not at issue with his people, but with merely a very inconsiderable clique among them, who had never liked him; and that it was much a joke to describe him as disaffected to his sovereign, simply because he had held his preparation services on the day of her coronation. in order to make good my first point, i took the unpardonable liberty of giving the names in full, in a letter which appeared in our northern newspapers, of every individual who walked in the procession, and represented themselves as the people; and challenged the addition of even a single name to a list ludicrously brief. and in making good the second, i fairly succeeded, as there were not a few comical circumstances in the transaction, in getting the laughers on my side. the clique was amazingly angry, and wrote not very bright letters, which appeared as advertisements in the newspapers, and paid duty to make evident the fact. there was a shallow and very ignorant young shoemaker in the place, named chaucer, a native of the south of scotland, who represented himself as the grandson of the old poet of the days of edward iii., and wrote particularly wretched doggrel to make good his claim. and, having a quarrel with the kirk-session, in a certain delicate department, he had joined the processionists, and celebrated their achievements in a ballad entirely worthy of them. and it was perhaps the severest cut of all, that the recognised leader of the band pronounced chaucer the younger a greatly better poet than me. there were representations, too, made to my superiors in the banking department at edinburgh, which procured me a reprimand, though a gentle one; but my superior in cromarty--mr. ross--as wise and good a man as any in the direction, and thoroughly acquainted with the merits of the case, was wholly on my side. i am afraid the reader may deem all this very foolish, and hold that i would have been better employed among the rocks, in determining the true relations of their various beds, and the character of their organisms, than in bickering in a petty village quarrel, and making myself enemies. and yet, man being what he is, i fear an ability of efficient squabbling is a greatly more marketable one than any ability whatever of extending the boundaries of natural science. at least so it was, that while my geological researches did nothing for me at this time, my letter in the procession controversy procured for me the offer of a newspaper editorship. but though, in a pecuniary point of view, i should have considerably bettered my circumstances by closing with it, i found i could not do so without assuming the character of the special pleader, and giving myself to the advocacy of views and principles which i really did not hold; and so i at once declined the office, as one for which i did not deem myself suited, and could not in conscience undertake. i found about this time more congenial employment, though, of course, it occupied only my leisure hours, in writing the memoir of a townsman--the late mr. william forsyth, of cromarty--at the request of his relation and son in-law, my friend mr. isaac forsyth, of elgin. william forsyth had been a grown man ere the abolition of the hereditary jurisdictions; and from the massiveness and excellence of his character, and his high standing as a merchant, in a part of the country in which merchants at the time were few, he had succeeded, within the precincts of the town, to not a little of the power of the hereditary sheriff of the district; and after acting for more than half a century as a laborious justice of the peace, and succeeding in making up more quarrels than most country lawyers have an opportunity of fomenting--for the age was a rude and combative one, and the merchant ever a peace-maker--he lived long enough to see liberty-and-equality clubs and processions, and died about the close of the first war of the french revolution. it was an important half-century in scotland--though it exhibits but a narrow, inconspicuous front in the history of the country--that intervened between the times of the hereditary jurisdictions and the liberty-and-equality clubs. it was specially the period during which popular opinion began to assume its potency, and in which the scotland of the past merged, in consequence, into the very dissimilar scotland of the present. and i derived much pleasure in tracing some of the more striking features of this transition age in the biography of mr. forsyth. my little work was printed, but not published, and distributed by mr. forsyth of elgin among the friends of the family, as perhaps a better and more adequate memorial of a worthy and able man than could be placed over his grave. it was on the occasion of the death of his last-surviving child--the late mrs. mackenzie of cromarty, a lady from whom i had received much kindness, and under whose hospitable roof i had the opportunity afforded me of meeting not a few superior men--that my memoir was undertaken; and i regarded it as a fitting tribute to a worthy family just passed away, at once deserving of being remembered for its own sake, and to which i owed a debt of gratitude. in the spring of , a sad bereavement darkened my household, and for a time left me little heart to pursue my wonted amusements, literary or scientific. we had been visited, ten months after our marriage, by a little girl, whose presence had added not a little to our happiness; home became more emphatically such from the presence of the child, that in a few months had learned so well to know its mother, and in a few more to take its stand in the nurse's arms, at an upper window that commanded the street, and to recognise and make signs to its father as he approached the house. its few little words, too, had a fascinating interest to our ears;--our own names, lisped in a language of its own, every time we approached; and the simple scotch vocable "awa, awa," which it knew how to employ in such plaintive tones as we retired, and that used to come back upon us in recollection, like an echo from the grave, when, its brief visit over, it had left us for ever, and its fair face and silken hair lay in darkness amid the clods of the churchyard. in how short a time had it laid hold of our affections! two brief years before, and we knew it not; and now it seemed as if the void which it left in our hearts the whole world could not fill. we buried it beside the old chapel of st. regulus, with the deep rich woods all around, save where an opening in front commands the distant land and the blue sea; and where the daisies which it had learned to love, mottled, starlike, the mossy mounds; and where birds, whose songs its ear had become skilful enough to distinguish, pour their notes over its little grave. the following simple but truthful stanzas, which i found among its mother's papers, seem to have been written in this place--sweetest of burying grounds--a few weeks after its burial, when a chill and backward spring, that had scowled upon its lingering illness, broke out at once into genial summer:-- thou'rt "awa, awa," from thy mother's side, and "awa, awa," from thy father's knee; thou'rt "awa" from our blessing, our care, our caressing, but "awa" from our hearts thou'lt never be. all things, dear child, that were wont to please thee are round thee here in beauty bright,-- there's music rare in the cloudless air, and the earth is teeming with living delight. thou'rt "awa, awa," from the bursting spring time, tho' o'er thy head its green boughs wave; the lambs are leaving their little footprints upon the turf of thy new-made grave. and art thou "awa," and "awa" for ever, that little face,--that tender frame,-- that voice which first, in sweetest accent call'd me the mother's thrilling name, that head of nature's finest moulding,-- those eyes, the deep night ether's blue where sensibility its shadows of ever-changing meaning throw? thy sweetness, patience under suffering, all promised us an opening day most fair, and told that to subdue thee would need but love's most gentle sway. ah me! 'twas here i thought to lead thee, and tell thee what are life and death, and raise thy serious thought's first waking to him who holds our every breath. and does my selfish heart then grudge thee, that angels are thy teachers now,-- that glory from thy saviour's presence kindles the crown upon thy brow? o no! to me earth must be lonelier, wanting thy voice, thy hand, thy love; yet dost thou dawn a star of promise, mild beacon to the world above. chapter xxv. "all for the church, and a little less for the state."--belhaven. i had taken no very deep interest in the voluntary controversy. there was, i thought, a good deal of over-statement and exaggeration on both sides. on the one hand, the voluntaries failed to convince me that a state endowment for ecclesiastical purposes is in itself in any degree a bad thing. i had direct experience to the contrary. i had evidence the most unequivocal that in various parts of the country it was a very excellent thing indeed. it had been a very excellent thing, for instance, in the parish of cromarty, ever since the revolution, down to the death of mr. smith--in reality a valuable patrimony of the people there; for it had supplied the parish, free of cost, with a series of popular and excellent ministers, whom otherwise the parishioners would have had to pay for themselves. and it had now given us my friend mr. stewart, one of the ablest and honestest ministers in scotland, or elsewhere, whether established or dissenting. and these facts, which were but specimens of a numerous class, had a tangibility and solidity about them which influenced me more than all the theoretic reasonings pressed on my attention about the mischief done to the church by the over-kindness of constantine, or the corrupting effects of state favour. but then i could as little agree with some of my friends on the endowment side, that the establishment, even in scotland, was everywhere of value, as with some of the voluntaries that it was nowhere of any. i had resided for months together in various parts of the country, where it would have mattered not a farthing to any one save the minister and his family, though the establishment had been struck down at a blow. religion and morals would have no more suffered by the annihilation of the minister's stipend, than by the suppression of the pension of some retired supervisor or superannuated officer of customs. nor could i forget, that the only religion, or appearance of religion, that existed in parties of workmen among which i had been employed (as in the south of scotland, for instance), was to be found among their dissenters--most of them, at the time, asserters of the voluntary principle. if the other workmen were reckoned, statistically at least, adherents of the establishment, it was not because they either benefited by it or cared for it, but only somewhat in the way that, according to the popular english belief, persons born at sea are held to belong to the parish of stepney. further, i did not in the least like the sort of company into which the voluntary controversy had introduced the good men on both sides; it gave a common cause to the voluntary and the infidel, and drew them cordially together; and, on the other hand, placed side by side, on terms portentously friendly, the pious asserter of endowments and the irreligious old tory. there was religion on both sides of the controversy, but a religious controversy it was not. the position of my grandmother's family, including of course uncles james and sandy, was a sort of midway one between the secession and the establishment. my grandmother had quitted the family of donald roy long ere he had been compelled, very unwillingly, to leave the church; and as no forced settlements had taken place in the parish into which she had removed, and as its ministers had been all men of the right stamp, she had done what donald himself had been so desirous to do--remained an attached member of the establishment. one of her sisters had, however, married in nigg; and she and her husband, following donald into the ranks of the secession, had reared one of their boys to the ministry, who became, in course of time, the respected minister of the congregation which his great-grandfather had founded. and, as the contemporary and first cousin of my uncles, the minister used to call upon them every time he came to town; and my uncle james, in turn (uncle sandy very rarely went to the country), never missed, when in nigg or its neighbourhood, to repay his visits. there was thus a good deal of intercourse kept up between the families, not without effect. most of the books of modern theology which my uncles read were secession books, recommended by their cousin; and the religious magazine for which they subscribed was a secession magazine. the latter bore, i remember, the name of the "christian magazine, or evangelical repository." it was not one of the brightest of periodicals, but a sound and solid one, with, as my uncles held, a good deal of the old unction about it; and there was, in especial, one of the contributors whose papers they used to pick out as of peculiar excellence, and not unfrequently read a second time. they bore the somewhat greek-looking signature of _leumas_, as if the writer had been a brother or cousin-german of some of the old christians to whom paul used to notify kind regards and good wishes at the end of his epistles; but it was soon discovered that _leumas_ was merely the proper name samuel reversed, though who the special samuel was who turned his signature to the right about, placing the wrong end foremost, and wrote with all the concise weight and gravity of the old divines, my uncles never knew. they had both passed away ere, in perusing the "second gallery of literary portraits," i found myself introduced to worthy old _leumas_, also a denizen of the unseen world at the time, as the father of the writer of that brilliant work--the rev. george gilfillan of dundee. this kind of writing had, of course, its proper effect on my uncles, and, through them, on the family: it kept up our respect for the secession. the established church, too, was in those days a tolerably faulty institution. my uncles took an interest in missions; and the church had none: nay, its deliberate decision against them--that of --remained still unreversed. it had had, besides, its forced settlements in our immediate neighbourhood; and moderatism, wise and politic in its generation, had perpetrated them by the hands of some of the better ministers of the district, who had learned to do what they themselves believed to be very wicked things, when their church bade them--a sort of professional license which my uncles could not in the least understand. in short, the secession better pleased them, in the main, than the establishment, though to the establishment they continued to adhere, and failed to see on what seceder principle their old friends were becoming voluntaries. on the breaking out of the controversy, i remembered all this; and, when told by good men of the established church that well-nigh all the vital religion of the country was on our side, and that it had left the voluntary seceders, though the good men themselves honestly believed what they said, i could not. further, the heads of a conversation which i had overheard in my cousin the seceder minister's house when i was a very young boy, and to which it could have been little suspected that i was listening--for i was playing at the time on the floor--had taken a strong hold of my memory, and often returned upon me at this period. my cousin and some of his elders were mourning--very sincerely, i cannot doubt--over the decay of religion among them: they were falling far short, they said, of the attainments of their fathers; there were no donald roys among them now; and yet they felt it to be a satisfaction, though a sad one, that the little religion which there was in the district seemed to be all among themselves. and now here was there exactly the same sort of conviction, equally strong, on the other side. but with all that liberally-expressed charity which forms one of the distinctive features of the present time, and is in reality one of its best things, there is still a vast amount of appreciation of this partial kind. friends are seen in the christian aspect; opponents in the polemic one; and it is too often forgotten that the friends have a polemic aspect to their opponents, and the opponents a christian aspect to their friends. and not only in the present, but at all former periods, the case seems to have been the same. i am sometimes half disposed to think, that either the prophet elijah, or the seven thousand honest men who had not bowed the knee to baal, must have been dissenters. had the prophet been entirely at one in his views with the seven thousand, it is not easy to conceive how he could have been wholly ignorant of their existence. with all these latitudinarian convictions, however, i was thoroughly an establishment man. the revenues of the scottish church i regarded, as i have said, as the patrimony of the scottish people; and i looked forward to a time when that unwarrantable appropriation of them, through which the aristocracy had sought to extend its influence, but which had served only greatly to reduce its power in the country, would come to an end. what i specially wanted, in short, was, not the confiscation of the people's patrimony, but simply its restoration from the moderates and the lairds. and in the enactment of the veto law i saw the process of restoration fairly begun. i would have much preferred seeing a good broad anti-patronage agitation raised on the part of the church. as shrewdly shown at the time by the late dr. m'crie, such a course would have been at once wiser and safer. but for such an agitation even the church's better ministers were not in the least prepared. from to --a period of seventy-two years--the general assembly had yearly raised its voice against the enactment of the patronage law of queen anne, as an unconstitutional encroachment on those privileges of the church and those rights of the scottish people which the treaty of union had been framed to secure. but the half century which had passed, since through the act of a moderate majority the protest had been dropped, had produced the natural effect. by much the greater part of even the better ministers of the church had been admitted into their offices through the law of patronage; and, naturally grateful to the patrons who had befriended them, they hesitated to make open war on the powers that had been exerted in their own behalf. according to solomon, the "gift" had to a certain extent "destroyed the heart;" and so they were prepared to take up merely a half-way position, which their predecessors, the old popular divines, would have liked exceedingly ill. i could not avoid seeing that, fixed in a sort of overtopped hollow, if i may so speak, between the claims of patronage on the one hand, and the rights of the people on the other, it was a most perilous position, singularly open to misconception and misrepresentation on both sides; and as it virtually stripped the patrons of half their power, and extended to the people only half their rights, i was not a little afraid that the patrons might be greatly more indignant than the people grateful, and that the church might, in consequence, find herself exposed to the wrath of very potent enemies, and backed by the support of only lukewarm friends. but however perilous and difficult as a post of occupation, it was, i could not avoid believing, a position conscientiously taken up; nor could i doubt that its grounds were strictly constitutional. the church, in a case of disputed settlement, might, i believed, have to forfeit the temporalities if her decision differed from that of the law courts, but only the temporalities connected with the case at issue; and these i deemed worth risking in the popular behalf, seeing that they might be regarded as already lost to the country in every case in which a parish was assigned to a minister whom the parishioners refused to hear. it rejoiced me, too, to see the revival of the old spirit in the church; and so i looked with an interest on the earlier stages of her struggle with the law courts, greatly more intense than that with which any mere political contest had ever inspired me. i saw with great anxiety decision after decision go against her; first that of the court of session in march , and next that of the house of lords in may ; and then, with the original auchterarder case of collision, i saw that of lethendy and marnoch mixed up; and, as one entanglement succeeded another, confusion becoming worse confounded. it was only when the church's hour of peril came that i learned to know how much i really valued her, and how strong and numerous the associations were that bound her to my affections. i had experienced at least the average amount of interest in political measures whose tendency and principles i deemed good in the main--such as the reform bill, the catholic emancipation act, and the emancipation of the negroes; but they had never cost me an hour's sleep. now, however, i felt more deeply; and for at least one night, after reading the speech of lord brougham, and the decision of the house of lords in the auchterarder case, i slept none. in truth, the position of the church at this time seemed critical in the extreme. offended by the usage which she had received at the hands of the whigs, in her claims for endowments to her new chapels, and startled by their general treatment of the irish establishment, and the suppression of the ten bishoprics, she had thrown her influence into the tory scale, and had done much to produce that reaction against the liberal party in scotland which took place during the ministry of lord melbourne. in the representation of at least one county in which he was all-potent--ross-shire--she had succeeded in substituting a tory for a whig; and there were few districts in the kingdom in which she had not very considerably increased the votes on the tory, or, as it was termed, conservative side. the people, however, though they might, and did, become quite indifferent enough to the whigs, could not follow her into the tory ranks. they stood aloof--very suspicious, not without reason, of her new political friends--no admirers of the newspapers which she patronized, and not in the least able to perceive the nature of the interest which she had begun to take in supernumerary bishops and the irish establishment. and now, when once more in a position worthy of her old character, and when her tory friends--converted at once into the bitterest and most ungenerous of enemies--were turning upon her to rend her, she had at once to encounter the hostility of the whigs, and the indifferency of the people. further, with but one, or at most two exceptions, all the newspapers which she had patronized declared against her, and were throughout the struggle the bitterest and most abusive of her opponents. the voluntaries, too, joined with redoubled vehemence in the cry raised to drown her voice, and misinterpret and misrepresent her claims. the general current of opinion ran strongly against her. my minister, warmly interested in the success of the non-intrusion principle, has told me, that for many months past i was the only man in his parish that seemed thoroughly to sympathize with him; and i have no doubt that the late dr. george cook was perfectly correct and truthful when he about this time remarked, in one of his public addresses, that he could scarce enter an inn or a stage-coach without finding respectable men inveighing against the utter folly of the non-intrusionists, and the worse than madness of the church courts. could i do nothing for my church in her hour of peril? there was, i believed, no other institution in the country half so valuable, or in which the people had so large a stake. the church was of right theirs--a patrimony won for them by the blood of their fathers, during the struggles and sufferings of more than a hundred years; and now that her better ministers were trying, at least partially, to rescue that patrimony for them from the hands of an aristocracy who, as a body at least, had no spiritual interest in the church--belonging, as most of its members did, to a different communion--they were in danger of being put down, unbacked by the popular support which in such a cause they deserved. could i not do something to bring up the people to their assistance? i tossed wakefully throughout a long night, in which i formed my plan of taking up the purely popular side of the question; and in the morning i sat down to state my views to the people, in the form of a letter addressed to lord brougham. i devoted to my new employment every moment not imperatively demanded by my duties in the bank office, and, in about a week after, was able to despatch the manuscript of my pamphlet to the respected manager of the commercial bank--mr. robert paul--a gentleman from whom i had received much kindness when in edinburgh, and who, in the great ecclesiastical struggle, took decided part with the church. mr. paul brought it to his minister, the rev. mr. candlish of st. george's (now dr. candlish), who, recognising its popular character, urged its immediate publication; and the manuscript was accordingly put into the hands of mr. johnstone, the well-known church bookseller. dr. candlish had been one of a party of ministers and elders of the evangelical majority who had met in edinburgh shortly before, to take measures for the establishment of a newspaper. all the edinburgh press, with the exception of one newspaper, had declared against the ecclesiastical party; and even that one rather received articles and paragraphs in their behalf through the friendship of the proprietor, than was itself on their side. there had been a larger infusion of whiggism among the edinburgh churchmen than in any other part of the kingdom. they had seen very much, in consequence, that the line taken by the conservative portion of their friends, in addressing the people through the press, had not been an efficient one;--their friends had set themselves to make the people both good conservatives and good churchmen, and of course had never got over the first point, and never would; and what they now proposed was, to establish a paper that, without supporting any of the old parties in the state, should be as liberal in its politics as in its churchmanship. but there was a preliminary point which they also could not get over. all the ready-made editors of the kingdom, if i may so speak, had declared against them; and for want of an editor, their meeting had succeeded in originating, not the intended newspaper, but merely a formal recognition, in a few resolutions, of its desirableness and importance. on reading my pamphlet in manuscript, however, dr. candlish at once concluded that the desiderated want was to be supplied by its writer. here, he said, is the editor we have been looking for. meanwhile, my little work issued from the press, and was successful. it ran rapidly through four editions of a thousand copies each--the number, as i subsequently ascertained, of a popular non-intrusion pamphlet that would fairly _sell_--and was read pretty extensively by men who were not non-intrusionists. among these there were several members of the ministry of the time, including the late lord melbourne, who at first regarded it, as i have been informed, as the composition, under a popular form and a _nom de guerre_, of some of the non-intrusion leaders in edinburgh; and by the late mr. o'connell, who had no such suspicions, and who, though he lacked sympathy, as he said, with the ecclesiastical views which it advocated, enjoyed what he termed its "racy english," and the position in which it placed the noble lord to whom it was addressed. it was favourably noticed, too, by mr. gladstone, in his elaborate work on church principles; and was, in short, both in the extent of its circulation, and the circles into which it found its way, a very successful pamphlet. so filled was my mind with our ecclesiastical controversy, that, while yet unacquainted with the fate of my first _brochure_, i was busily engaged with a second. a remarkable case of intrusion had occurred in the district rather more than twenty years before; and after closing my week's labours in the bank, i set out for the house of a friend in a neighbouring parish on a saturday evening, that i might attend the deserted church on the following sabbath, and glean from actual observation the materials of a truthful description, which would, i trusted, tell in the controversy. and as the case was one of those in which truth proves stronger than fiction, what i had to describe was really very curious; and my description received an extensive circulation. i insert the passage entire, as properly a part of my story. "there were associations of a peculiarly high character connected with this northern parish. for more than a thousand years it had formed part of the patrimony of a truly noble family, celebrated by philip doddridge for its great moral worth, and by sir walter scott for its high military genius; and through whose influence the light of the reformation had been introduced into this remote corner, at a period when the neighbouring districts were enveloped in the original darkness. in a later age it had been honoured by the fines and proscriptions of charles ii.; and its minister--one of those men of god whose names still live in the memory of the country, and whose biography occupies no small space in the recorded history of her 'worthies'--had rendered himself so obnoxious to the tyranny and irreligion of the time, that he was ejected from his charge more than a year before any of the other non-conforming clergymen of the church.[ ] i approached the parish from the east. the day was warm and pleasant; the scenery through which i passed, some of the finest in scotland. the mountains rose on the right, in huge titanic masses, that seemed to soften their purple and blue in the clear sunshine, to the delicate tone of the deep sky beyond; and i could see the yet unwasted snows of winter glittering, in little detached masses, along their summits. the hills of the middle region were feathered with wood; a forest of mingled oaks and larches, which still blended the tender softness of spring with the full foliage of summer, swept down to the path; the wide undulating plain below was laid out into fields, mottled with cottages, and waving with the yet unshot corn; and a noble arm of the sea winded along the lower edge for nearly twenty miles, losing itself to the west among blue hills and jutting headlands, and opening in the east to the main ocean, through a magnificent gateway of rock. but the little groups which i encountered at every turning of the path, as they journeyed, with all the sober, well-marked decency of a scottish sabbath morning, towards the church of a neighbouring parish, interested me more than even the scenery. the clan which inhabited this part of the country had borne a well-marked character in scottish story. buchanan had described it as one of the most fearless and warlike in the north. it served under the bruce at bannockburn. it was the first to rise in arms to protect queen mary, on her visit to inverness, from the intended violence of huntly. it fought the battles of protestantism in germany, under gustavus adolphus. it covered the retreat of the english at fontenoy; and presented an unbroken front to the enemy, after all the other troops had quitted the field. and it was the descendants of those very men who were now passing me on the road. the rugged, robust form, half bone, half muscle--the springy firmness of the tread--the grave, manly countenance--all gave indication that the original characteristics survived in their full strength; and it was a strength that inspired confidence, not fear. there were grey-haired, patriarchal-looking men among the groups, whose very air seemed impressed by a sense of the duties of the day; nor was there aught that did not agree with the object of the journey, in the appearance of even the youngest and least thoughtful. "as i proceeded, i came up with a few people who were travelling in a contrary direction. a secession meeting-house has lately sprung up in the parish, and these formed part of the congregation. a path, nearly obscured by grass and weeds, leads from the main road to the parish church. it was with difficulty i could trace it, and there were none to direct me, for i was now walking alone. the parish burying-ground, thickly sprinkled with graves and tombstones, surrounds the church. it is a quiet, solitary spot, of great beauty, lying beside the sea-shore; and as service had not yet commenced, i whiled away half an hour in sauntering among the stones, and deciphering the inscriptions. i could trace in the rude monuments of this retired little spot, a brief but interesting history of the district. the older tablets, grey and shaggy with the mosses and lichens of three centuries, bear, in their uncouth semblances of the unwieldy battle-axe and double-handed sword of ancient warfare, the meet and appropriate symbols of the earlier time. but the more modern testify to the introduction of a humanizing influence. they speak of a life after death, in the "holy texts" described by the poet; or certify, in a quiet humility of style which almost vouches for their truth, that the sleepers below were "honest men, of blameless character, and who feared god." there is one tombstone, however, more remarkable than all the others. it lies beside the church-door, and testifies, in an antique inscription, that it covers the remains of the "great.man.of.god.and.faithful.minister.of jesus.christ.," who had endured persecution for the truth in the dark days of charles and his brother. he had outlived the tyranny of the stuarts; and, though worn by years and sufferings, had returned to his parish on the revolution, to end his course as it had begun. he saw, ere his death, the law of patronage abolished, and the popular right virtually secured; and, fearing lest his people might be led to abuse the important privilege conferred upon them, and calculating aright on the abiding influence of his own character among them, he gave charge on his deathbed to dig his grave in the threshold of the church, that they might regard him as a sentinel placed at the door, and that his tombstone might speak to them as they passed out and in. the inscription, which, after the lapse of nearly a century and a half, is still perfectly legible, concludes with the following remarkable words:--"this.stone.shall.bear.witness. against.the.parishioners.of.kiltearn.if.they.bring.ane.ungodly. minister.in.here." could the imagination of a poet have originated a more striking conception in connexion with a church deserted by all its better people, and whose minister fattens on his hire, useless and contented? "i entered the church, for the clergyman had just gone in. there were from eight to ten persons scattered over the pews below, and seven in the galleries above; and these, as there were no more '_peter clarks_' or '_michael tods_'[ ] in the parish, composed the entire congregation. i wrapped myself up in my plaid, and sat down; and the service went on in the usual course; but it sounded in my ears like a miserable mockery. the precentor sung almost alone; and ere the clergyman had reached the middle of his discourse, which he read in an unimpassioned, monotonous tone, nearly one-half his skeleton congregation had fallen asleep; and the drowsy, listless expression of the others showed that, for every good purpose, they might have been asleep too. and sabbath after sabbath has this unfortunate man gone the same tiresome round, and with exactly the same effects, for the last twenty-three years;--at no time regarded by the better clergymen of the district as really their brother;--on no occasion recognised by the parish as virtually its minister;--with a dreary vacancy and a few indifferent hearts inside his church, and the stone of the covenanter at the door. against whom does the inscription testify? for the people have escaped. against the patron, the intruder, and the law of bolingbroke--the dr. robertsons of the last age, and the dr. cooks of the present. it is well to learn from this hapless parish the exact sense in which, in a different state of matters, the rev. mr. young would have been constituted minister of auchterarder. it is well, too, to learn, that there may be vacancies in the church where no blank appears in the almanac." on my return home from this journey, early on the following monday, i found a letter from edinburgh awaiting me, requesting me to meet there with the leading non-intrusionists. and so after describing, in the given extract, the scene which i had just witnessed, and completing my second pamphlet, i set out for edinburgh, and saw for the first time men with whose names i had been familiar during the course of the voluntary and non-intrusion controversies. and entering into their plans, though with no little shrinking of heart, lest i should be found unequal to the demands of a twice-a-week paper, that would have to stand, in ishmael's position, against almost the whole newspaper press of the kingdom, i agreed to undertake the editorship of their projected newspaper, the _witness_. save for the intense interest with which i regarded the struggle, and the stake possessed in it, as i believed, by the scottish people, no consideration whatever would have induced me to take a step so fraught, as i thought at the time, with peril and discomfort. for full twenty years i had never been engaged in a quarrel on my own account: all my quarrels, either directly or indirectly, were ecclesiastical ones;--i had fought for my minister, or for my brother parishioners: and fain now would i have lived at peace with all men; but the editorship of a non-intrusion newspaper involved, as a portion of its duties, war with all the world. i held, besides--not aware how very much the spur of necessity quickens production--that its twice-a-week demands would fully occupy all my time, and that i would have to resign, in consequence, my favourite pursuit--geology. i had once hoped, too--though of late years the hope had been becoming faint--to leave some little mark behind me in the literature of my country; but the last remains of the expectation had now to be resigned. the newspaper editor writes in sand when the flood is coming in. if he but succeed in influencing opinion for the present, he must be content to be forgotten in the future. but believing the cause to be a good one, i prepared for a life of strife, toil, and comparative obscurity. in counting the cost, i very considerably exaggerated it; but i trust i may say that, in all honesty, and with no sinister aim, or prospect of worldly advantage, i _did_ count it, and fairly undertook to make the full sacrifice which the cause demanded. it was arranged that our new paper should start with the new twelvemonth ( ); and i meanwhile returned to cromarty, to fulfil my engagements with the bank till the close of its financial year, which in the commercial bank offices takes place at the end of autumn. shortly after my return, dr. chalmers visited the place on the last of his church extension journeys; and i heard, for the first time, that most impressive of modern orators address a public meeting, and had a curious illustration of the power which his "_deep mouth_" could communicate to passages little suited, one might suppose, to call forth the vehemency of his eloquence. in illustrating one of his points, he quoted from my "memoir of william forsyth" a brief anecdote, set in description of a kind which most men would have read quietly enough, but which, coming from him, seemed instinct with the homeric vigour and force. the extraordinary impressiveness which he communicated to the passage served to show me, better than aught else, how imperfectly great orators may be represented by their written speeches. admirable as the published sermons and addresses of dr. chalmers are, they impart no adequate idea of that wonderful power and impressiveness in which he excelled all other british preachers.[ ] i had been introduced to the doctor in edinburgh a few weeks before; but on this occasion i saw rather more of him. he examined with curious interest my collection of geological specimens, which already contained not a few valuable fossils that could be seen nowhere else; and i had the pleasure of spending the greater part of a day in visiting in his company, by boat, some of the more striking scenes of the cromarty sutors. i had long looked up to chalmers as, on the whole, the man of largest mind which the church of scotland had ever produced;--not more intense or practical than knox, but broader of faculty; nor yet fitted by nature or accomplishment to make himself a more enduring name in literature than robertson, but greatly nobler in sentiment, and of a larger grasp of general intellect. with any of our other scottish ministers it might be invidious to compare him; seeing that some of the ablest of them are, like henderson, little more than mere historic portraits drawn by their contemporaries, but whose true intellectual measure cannot, from the lack of the necessary materials on which to form a judgment, be now taken anew; and that many of the others employed fine faculties in work, literary and ministerial, which, though important in its consequences, was scarce less ephemeral in its character than even the labours of the newspaper editor. the mind of chalmers was emphatically a many-sided one. few men ever came into friendly contact with him, who did not find in it, if they had really anything good in them, moral or intellectual, a side that suited themselves; and i had been long struck by that union which his intellect exhibited of a comprehensive philosophy with a true poetic faculty, very exquisite in quality, though dissociated from what wordsworth terms the "accomplishment of verse." i had not a little pleasure in contemplating him on this occasion as the _poet_ chalmers. the day was calm and clear; but there was a considerable swell rolling in from the german ocean, on which our little vessel rose and fell, and which sent the surf high against the rocks. the sunshine played amid the broken crags a-top, and amid the foliage of an overhanging wood; or caught, half-way down, some projecting tuft of ivy; but the faces of the steeper precipices were brown in the shade; and where the wave roared in deep caves beneath, all was dark and chill. there were several members of the party who attempted engaging the doctor in conversation; but he was in no conversational mood. it would seem as if the words addressed to his ear failed at first to catch his attention, and that, with a painful courtesy, he had to gather up their meaning from the remaining echoes, and to reply to them doubtfully and monosyllabically, at the least possible expense of mind. his face wore, meanwhile, an air of dreamy enjoyment. he was busy, evidently, among the crags and bosky hollows, and would have enjoyed himself more had he been alone. in the middle of one noble precipice, that reared its tall pine-crested brow more than a hundred yards overhead, there was a bush-covered shelf of considerable size, but wholly inaccessible; for the rock dropped sheer into it from above, and then sank perpendicularly from its outer edge to the beach below; and the insulated shelf, in its green unapproachable solitude, had evidently caught his eye. _it_ was the scene, i said--taking the direction of his eye as the antecedent for the _it_,--it was the scene, says tradition, of a sad tragedy during the times of the persecution of charles. a renegade chaplain, rather weak than wicked, threw himself, in a state of wild despair, over the precipice above; and his body, intercepted in its fall by that shelf, lay unburied among the bushes for years after, until it had bleached into a dry and whitened skeleton. even as late as the last age, the shelf continued to retain the name of the "chaplain's lair." i found that my communication, chiming in with his train of cogitation at the time, caught both his ear and mind; and his reply, though brief, was expressive of the gratification which its snatch of incident had conveyed. as our skiff sped on a few oar-lengths more, we disturbed a flock of sea-gulls, that had been sporting in the sunshine over a shoal of sillocks; and a few of them winged their way to a jutting crag that rose immediately beside the shelf. i saw chalmers' eye gleam as it followed them. "would you not like, sir," he said, addressing himself to my minister, who sat beside him--"would you not like to be a sea-gull? i think _i_ would. sea-gulls are free of the three elements--earth, air, and water. these birds were sailing but half a minute since without boat, at once angling and dining, and now they are already rusticating in the chaplain's lair. i think i could enjoy being a sea-gull." i saw the doctor once afterwards in a similar mood. when on a visit to him in burnt-island, in the following year, i marked, on approaching the shore by boat, a solitary figure stationed on the sward-crested trap-rock which juts into the sea immediately below the town; and after the time spent in landing and walking round to the spot, there was the solitary figure still, standing motionless as when first seen. it was chalmers--the same expression of dreamy enjoyment impressed on his features as i had witnessed in the little skiff, and with his eyes turned on the sea and the opposite land. it was a lovely morning. a faint breeze had just begun to wrinkle in detached belts and patches the mirror-like blackness of the previous calm, in which the broad firth had lain sleeping since day-break; and the sunlight danced on the new-raised wavelets; while a thin long wreath of blue mist, which seemed coiling its tail like a snake round the distant inchkeith, was slowly raising the folds of its dragon-like neck and head from off the scottish capital, dim in the distance, and unveiling fortalice, and tower, and spire, and the noble curtain of blue hills behind. and there was chalmers, evidently enjoying the exquisiteness of the scene, as only by the true poet scenery can be enjoyed. those striking metaphors which so abound in his writings, and which so often, without apparent effort, lay the material world before the reader, show how thoroughly he must have drunk in the beauties of nature; the images retained in his mind became, like words to the ordinary man, the signs by which he thought, and, as such, formed an important element in the power of his thinking. i have seen his astronomical discourses disparagingly dealt with by a slim and meagre critic, as if they had been but the chapters of a mere treatise on astronomy--a thing which, of course, any ordinary man could write--mayhap even the critic himself. the astronomical discourses, on the other hand, no one could have written save chalmers. nominally a series of sermons, they in reality represent, and in the present century form perhaps the only worthy representatives of, that school of philosophic poetry to which, in ancient literature, the work of lucretius belonged, and of which, in the literature of our own country, the "seasons" of thomson, and akenside's "pleasures of the imagination," furnish adequate examples. he would, i suspect, be no discriminating critic who would deal with the "seasons" as if they formed merely the journal of a naturalist, or by the poem of akenside as if it were simply a metaphysical treatise. the autumn of this year brought me an unexpected but very welcome visitor, in my old marcus' cave friend finlay; and when i visited all my former haunts, to take leave of them ere i quitted the place for the scene of my future labours, i had him to accompany me. though for many years a planter in jamaica, his affections were still warm, and his literary tastes unchanged. he was a writer, as of old, of sweet simple verses, and as sedulous a reader as ever; and, had time permitted, we found we could have kindled fires together in the caves, as we had done more than twenty years before, and have ranged the shores for shell-fish and crabs. he had had, however, in passing through life, his full share of its cares and sorrows. a young lady to whom he had been engaged in early youth had perished at sea, and he had remained single for her sake. he had to struggle, too, in his business relations, with the embarrassments incident to a sinking colony; and though a west indian climate was beginning to tell on his constitution, his circumstances though tolerably easy, were not such as to permit his permanent residence in scotland. he returned in the following year to jamaica; and i saw, some time after, in a kingston paper, an intimation of his election to the colonial house of representatives, and the outline of a well-toned sensible address to his constituents, in which he urged that the sole hope of the colony lay in the education and mental elevation of its negro population to the standard of the people at home. i have been informed that the latter part of his life was, like that of many of the jamaica planters in their altered circumstances, pretty much a struggle; and his health at length breaking down, in a climate little favourable to europeans, he died about three years ago--with the exception of my friend of the doocot cave, now free church minister of nigg, the last of my marcus' cave companions. their remains lie scattered over half the globe. i closed my connexion with the bank at the termination of its financial year; gave a few weeks very sedulously to geology, during which i was fortunate enough to find specimens on which agassiz has founded two of his fossil species; got, at parting, an elegant breakfast-service of plate from a kind and numerous circle of friends, of all shades of politics and both sides of the church; and was entertained at a public dinner, at which i attempted a speech, that got on but indifferently, though it looked quite well enough in my friend mr. carruthers' report, and which was, i suppose, in some sort apologized for by the fiddlers, who struck up at its close, "a man's a man for a' that." it was, i felt, not the least gratifying part of the entertainment, that old uncle sandy was present, and that his health was cordially drunk by the company in the recognised character of my best and earliest friend. and then, taking leave of my mother and uncle, of my respected minister, and my honoured superior in the bank, mr. ross, i set out for edinburgh, and in a few days after was seated at the editorial desk--a point at which, for the present, the story of my education must terminate. i wrote for my paper during the first twelvemonth a series of geological chapters, which were fortunate enough to attract the notice of the geologists of the british association, assembled that year at glasgow, and which, in the collected form, compose my little work on the old red sandstone. the paper itself rose rapidly in circulation, till it ultimately attained to its place among what are known as our first-class scottish newspapers; and of its subscribers, perhaps a more considerable proportion of the whole are men who have received a university education, than can be reckoned by any other scotch journal of the same number of readers. and during the course of the first three years, my employers doubled my salary. i am sensible, however, that these are but small achievements. in looking back upon my youth, i see, methinks, a wild fruit tree, rich in leaf and blossom; and it is mortifying enough to mark how very few of the blossoms have set, and how diminutive and imperfectly formed the fruit is into which even the productive few have been developed. a right use of the opportunities of instruction afforded me in early youth would have made me a scholar ere my twenty-fifth year, and have saved to me at least ten of the best years of life--years which were spent in obscure and humble occupations. but while my story must serve to show the evils which result from truant carelessness in boyhood, and that what was sport to the young lad may assume the form of serious misfortune to the man, it may also serve to show, that much may be done by after diligence to retrieve an early error of this kind--that life itself is a school, and nature always a fresh study--and that the man who keeps his eyes and his mind open will always find fitting, though, it may be, hard schoolmasters, to speed him on in his lifelong education. footnotes: [ ] thomas hog of kiltearn. see "scots worthies" or the cheap-publication volumes of the free church for . [ ] peter clark and michael tod were the only individuals who, in a population of three thousand souls, attached their signatures to the _call_ of the obnoxious presentee, mr. young, in the famous auchterarder case. [ ] the following is the passage which was honoured on this occasion by chalmers, and which told, in his hands, with all the effect of the most powerful acting:--"saunders macivor, the mate of the 'elizabeth,' was a grave and somewhat hard-favoured man, powerful in bone and muscle, even after he had considerably turned his sixtieth year, and much respected for his inflexible integrity and the depth of his religious feelings. both the mate and his devout wife were especial favourites with mr. porteous of kilmuir--a minister of the same class as the pedens, renwicks, and cargils of a former age; and on one occasion when the sacrament was dispensed in his parish, and saunders was absent on one of his continental voyages, mrs. macivor was an inmate of the manse. a tremendous storm burst out in the night-time, and the poor woman lay awake, listening in utter terror to the fearful roarings of the wind, as it howled in the chimneys, and shook the casements and the doors. at length, when she could lie still no longer, she arose, and crept along the passage to the door of the minister's chamber. 'o, mr. porteous,' she said, 'mr. porteous, do ye no hear that?--and poor saunders on his way back frae holland! o, rise, rise, and ask the strong help o' your master!' the minister accordingly rose, and entered his closet. the 'elizabeth' at this critical moment was driving onwards through spray and darkness, along the northern shores of the moray firth. the fearful skerries of shandwick, where so many gallant vessels have perished, were close at hand; and the increasing roll of the sea showed the gradual shallowing of the water macivor and his old townsman, robert hossack, stood together at the binnacle. an immense wave came rolling behind, and they had but barely time to clutch to the nearest hold, when it broke over them half-mast high, sweeping spars, bulwarks, cordage, all before it, in its course. it passed, but the vessel rose not. her deck remained buried in a sheet of foam, and she seemed settling down by the head. there was a frightful pause. first, however, the bowsprit and the butts of the windlass began to emerge--next the forecastle--the vessel seemed as if shaking herself from the load; and then the whole deck appeared, as she went tilting over the next wave. 'there are still more mercies in store for us,' said macivor, addressing his companion: 'she floats still' 'o, saunders, saunders!' exclaimed robert, 'there was surely some god's soul at work for us, or she would never have _cowed_ you.'" _edinburgh: printed by m'farlane & erskine._ etna. [illustration: view of etna from catania] etna _a history of the mountain and of its eruptions._ by g. f. rodwell, science master in marlborough college. with maps and illustrations. [illustration] london c. kegan paul & co., , paternoster square [_the rights of translation and of reproduction are reserved._] i dedicate this book to my mother. preface. while preparing an account of mount etna for the encyclopædia britannica, i was surprised to find that there exists no single work in the english language devoted to the history of the most famous volcano in the world. i was consequently induced to considerably enlarge the encyclopædia article, and the following pages are the result. the facts recorded have been collected from various sources--german, french, italian, and english, and from my own observations made during the summer of . i desire to express my indebtedness to mr. frank rutley, of h.m. geological survey, for his careful examination of the lavas which were collected during my ascent of the mountain, and for the account which he has written of them; also to mr. john murray for permission to copy figures from lyell's "principles of geology." my thanks are also due to mr. george dennis, h.m. consul-general in sicily; mr. robert o. franck, vice-consul in catania; and to prof. orazio silvestri, for information with which they have severally supplied me. g. f. rodwell. marlborough, _september th, ._ contents. chapter i. history of the mountain. position.--name.--mention of etna by early writers.--pindar.-- Æschylus.--thucydides.--virgil.--strabo.--lucretius.--lucilius junior.--etna the home of early myths.--cardinal bembo.--fazzello.-- filoteo.--early maps of the mountain.--hamilton.--houel.--brydone.-- ferrara.--recupero.--captain smyth.--gemellaro; his map of etna.-- elie de beaumont.--abich.--hoffmann.--von waltershausen's _atlas des aetna_.--lyell.--map of the italian stato maggiore.--carlo gemellaro.--orazio silvestri. chapter ii. physical features of the mountain. height.--radius of vision from the summit.--boundaries.--area.-- population.--general aspect of etna.--the val del bove.--minor cones.--caverns.--position and extent of the three regions.-- regione coltivata.--regione selvosa.--regione deserta.--botanical regions.--divisions of rafinesque-schmaltz, and of presl.--animal life in the upper regions. chapter iii. ascent of the mountain. the most suitable time for ascending etna.--the ascent commenced.-- nicolosi.--etna mules.--night journey through the upper regions of the mountain.--brilliancy of the stars.--proposed observatory on etna.--the casa inglesi.--summit of the great crater.--sunrise from the summit.--the crater.--descent from the mountain.-- effects of refraction.--fatigue of the ascent. chapter iv. towns situated on the mountain. paterno.--ste. maria di licodia.--the site of the ancient town of aetna.--biancavilla.--aderno.--sicilian inns.--adranum.--bronte.-- randazzo.--mascali.--giarre.--aci reale.--its position.--the scogli de'ciclopi.--catania, its early history, and present condition. chapter v. eruptions of the mountain. their frequency within the historical period.-- b.c.-- b.c.-- b.c.-- b.c.-- b.c.-- b.c.-- b.c.-- b.c.-- b.c.-- b.c.-- b.c.-- b.c.-- a.d.-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- close of the fifteenth century.-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .--flood of .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- general character of the eruptions. chapter vi. geology and mineralogy of the mountain. elie de beaumont's classification of the rocks of etna.--hoffman's geological map.--lyell's researches.--the period of earliest eruption.--the val del bove.--two craters of eruption.--antiquity of etna.--the lavas of etna.--labradorite.--augite.--olivine.-- analcime.--titaniferous iron.--mr. rutley's examination of etna lavas under the microscope. list of illustrations. view of etna from catania _to face title._ topographical map of etna _to face page_ sections of etna " grotto delle palombe " the casa inglesi and cone of etna " view of the val de bove " view of etna from bronte " island of columnar basalt off trezza " geological map of etna " map of the val del bove (woodcut) ideal section of mount etna profile of etna sections of etna lavas seen under the microscope, _to face p._ [illustration: topographical map of etna] etna. a history of the mountain and of its eruptions. chapter i. history of the mountain. position.--name.--mention of etna by early writers.--pindar.-- Æschylus.--thucydides.--virgil.--strabo.--lucretius.--lucilius junior.--etna the home of early myths.--cardinal bembo.--fazzello.-- filoteo.--early maps of the mountain.--hamilton.--houel.--brydone.-- ferrara.--recupero.--captain smyth.--gemellaro; his map of etna.-- elie de beaumont.--abich.--hoffmann.--von waltershausen's _atlas des aetna_.--lyell.--map of the italian stato maggiore.--carlo gemellaro.--orazio silvestri. the principal mountain chain of sicily skirts the north and a portion of the north-eastern coast, and would appear to be a prolongation of the apennines. an inferior group passes through the centre of the island, diverging towards the south, as it approaches the east coast. between the two ranges, and completely separated from them by the valleys of the alcantara and the simeto, stands the mighty mass of mount etna, which rises in solitary grandeur from the eastern sea-board of the island. volcanoes, by the very mode of their formation, are frequently completely isolated; and, if they are of any magnitude, they thus acquire an imposing contour and a majesty, which larger mountains, forming parts of a chain, do not possess. this specially applies to etna. "coelebs degit," says cardinal bembo, "et nullius montis dignata conjugium, caste intra suos terminos continetur." it is not alone the conspicuous appearance of the mountain which has made it the most famous volcano either of ancient or modern times:--the number and violence of its eruptions, the extent of its lava streams, its association with antiquity, and its history prolonged over more than years, have all tended to make it celebrated. the geographical position of etna was first accurately determined by captain smyth in . he estimated the latitude of the highest point of the bifid peak of the great crater at ° ' " n.; and the longitude at ° east of greenwich. elie de beaumont repeated the observations in with nearly the same result; and these determinations have been very generally adopted. in the new italian map recently constructed by the stato maggiore, the latitude of the centre of the crater is stated to be ° ' " n., and the longitude ' " e. of the meridian of naples, which passes through the observatory of capo di monte. according to bochart the name of etna is derived from the phoenician _athana_--a furnace; others derive it from ~aithô~--to burn. professor benfey of gottingen, a great authority on the subject, considers that the word was created by one of the early indo-germanic races. he identifies the root _ait_ with the greek ~aith~ and the latin _aed_--to burn, as in _aes_-tu. the greek name ~aitna~ was known to hesiod. the more modern name, _mongibello_, by which the mountain is still commonly known to the sicilians, is a combination of the arabic _gibel_, and the italian _monte_. during the saracenic occupation of sicily, etna was called _gibel uttamat_--the mountain of fire; and the last syllables of mongibello are a relic of the saracenic name. a mountain near palermo is still called gibel rosso--the red mountain; and names may not unfrequently be found in the immediate neighbourhood of etna which are partly, or sometimes even entirely, composed of arabic words; such, for example, as _alcantara_--the river of _the bridge_. etna is also often spoken of distinctively as _il monte_--the mountain _par excellence_; a name which, in its capacity of the largest mountain in the kingdom of italy, and the loftiest volcano in europe, it fully justifies. etna is frequently alluded to by classical writers. by the poets it was sometimes feigned to be the prison of the giant enceladus or typhon, sometimes the forge of hephaistos, and the abode of the cyclops. it is strange that homer, who has so minutely described certain portions of the contiguous sicilian coast, does not allude to etna. this has been thought by some to be a proof that the mountain was in a quiescent state during the period which preceded and coincided with the time of homer. pindar (b.c. - ) is the first writer of antiquity who has described etna. in the first of the pythian odes for hieron, of the town of aitna, winner in the chariot race in b.c. , he exclaims: ... "he (typhon) is fast bound by a pillar of the sky, even by snowy etna, nursing the whole year's length her dazzling snow. whereout pure springs of unapproachable fire are vomited from the inmost depths: in the daytime the lava-streams pour forth a lurid rush of smoke; but in the darkness a red rolling flame sweepeth rocks with uproar to the wide deep sea.... that dragon-thing (typhon) it is that maketh issue from beneath the terrible fiery flood."[ ] [ ] translated by ernest myers, m.a., . Æschylus (b.c. - ) speaks also of the "mighty typhon," (_prometheus_ v.): . . . . . "he lies a helpless, powerless carcase, near the strait of the great sea, fast pressed beneath the roots of ancient etna, where on highest peak hephæstos sits and smites his iron red hot, from whence hereafter streams of fire shall burst, devouring with fierce jaws the golden plains of fruitful, fair sikelia."[ ] [ ] translated by e. myers. herein he probably refers to the eruption which had occurred a few years previously (b.c. ). thucydides (b.c. - ) alludes in the last lines of the third book to several early eruptions of the mountain in the following terms: "in the first days of this spring, the stream of fire issued from etna, as on former occasions, and destroyed some land of the catanians, who live upon mount etna, which is the largest mountain in sicily. fifty years, it is said, had elapsed since the last eruption, there having been three in all since the hellenes have inhabited sicily."[ ] [ ] translated by e. crawley. virgil's oft-quoted description of the mountain (_eneid_, bk. ) we give in the spirited translation of conington: "but etna with her voice of fear in weltering chaos thunders near. now pitchy clouds she belches forth of cinders red, and vapour swarth; and from her caverns lifts on high live balls of flame that lick the sky: now with more dire convulsion flings disploded rocks, her heart's rent strings, and lava torrents hurls to-day a burning gulf of fiery spray." many other early writers speak of the mountain, among them theokritos, aristotle, ovid, livy, seneca, lucretius, pliny, lucan, petronius, cornelius severus, dion cassius, strabo, diodorus siculus, and lucilius junior. seneca makes various allusions to etna, and mentions the fact that lightning sometimes proceeded from its smoke. strabo has given a very fair description of the mountain. he asserts that in his time the upper part of it was bare, and covered with ashes, and in winter with snow, while the lower slopes were clothed with forests. the summit was a plain about twenty stadia in circumference, surrounded by a ridge, within which there was a small hillock, the smoke from which ascended to a considerable height. he further mentions a second crater. etna was commonly ascended in strabo's time from the south-west. while the poets on the one hand had invested the mountain with various supernatural attributes, and had made it the prison-house of a chained giant, and the workshop of a swart god, lucretius endeavoured to show that the eruptions and other phenomena could be easily explained by the ordinary operations of nature. "and now at last," he writes, "i will explain in what ways yon flame, roused to fury in a moment, blazes forth from the huge furnaces of aetna. and, first, the nature of the whole mountain is hollow underneath, underpropped throughout with caverns of basalt rocks. furthermore, in all caves are wind and air, for wind is produced when the air has been stirred and put in motion. when this air has been thoroughly heated, and, raging about, has imparted its heat to all the rocks around, wherever it comes in contact with them, and to the earth, and has struck out from them fire burning with swift flames, it rises up and then forces itself out on high, straight through the gorges; and so carries its heat far, and scatters far its ashes, and rolls on smoke of a thick pitchy blackness, and flings out at the same time stones of prodigious weight--leaving no doubt that this is the stormy force of air. again, the sea, to a great extent, breaks its waves and sucks back its surf at the roots of that mountain. caverns reach from this sea as far as the deep gorges of the mountain below. through these you must admit [that air mixed up with water passes; and] the nature of the case compels [this air to enter in from that] open sea, and pass right within, and then go out in blasts, and so lift up flame, and throw out stones, and raise clouds of sand; for on the summit are craters, as they name them in their own language, what we call gorges and mouths."[ ] [ ] _de naturâ rerum_, book , p. . translated by e. munro . these ideas were developed by lucilius junior in a poem consisting of hexameters entitled _aetna_. the authorship of this poem has long been a disputed point; it has been attributed to virgil, claudian, quintilius varus, manilius, and, by joseph scaliger[ ] and others, to cornelius severus. wensdorff was the first to adduce reasons for attributing the poem to lucilius junior, and his views are generally adopted. lucilius junior was procurator of sicily under nero, and, while resident in the island, he ascended etna; and it is said that he proposed writing a detailed history of the mountain. he adopted the scientific opinions of epicurus, as established in rome by lucretius, and was more immediately a disciple of seneca. the latter dedicated to him his _quæstiones naturales_, in which he alludes more than once to etna. m. chenu speaks of the poem of lucilius junior as "sans doute très-póetique, mais assez souvent dur, heurté, concis, et parcela même, d'une obscurité parfois désespérante."[ ] at the commencement of the poem, lucilius ridicules the ideas of the poets as regards the connection of etna with vulcan and the cyclops. he has no belief in the practice, which apparently prevailed in his time, of ascending to the edge of the crater and there offering incense to the tutelary gods of the mountain. he adopts to a great extent the tone and style of lucretius, in his explanation of the phenomena of the mountain. water filters through the crevices and cracks in the rocks, until it comes into contact with the internal fires, when it is converted into vapour and expelled with violence. the internal fires are nourished by the winds which penetrate into the mountain. he traces some curious connection between the plants which grow upon the mountain, and the supply of sulphur and bitumen to the interior, which is, at best, but partly intelligible. [ ] see lucilius junioris aetna. recensuit notasque jos. scaligeri, frid. lindenbruchii et suas addidit fridericus jacob. lipsiæ, . [ ] l'etna de lucilius junior. traduction nouvelle par jules chenu. paris, . "nunc superant, quacunque regant incendia silvæ quæ flammis alimenta vacent, quid nutriat aetnam. incendi patiens illis vernacula caulis materia, appositumque igni genus utile terræ est, uritur assidue calidus nunc sulfuris humor, nunc spissus crebro præbetur flumine succus, pingue bitumen adest, et quidquid cominus acres irritat flammas; illius corporis Ætna est. atque hanc materiam penitus discurrere fontes infectæ erumpunt et aquæ radice sub ipsa." many of the myths developed by the earlier poets had their home in the immediate neighbourhood, sometimes upon the very sides, of etna--demeter seeking persephone; acis and galatea; polyphemus and the cyclops. mr. symonds tells us that the one-eyed giant polyphemus was etna itself, with its one great crater, while the cyclops were the many minor cones. "persephone was the patroness of sicily, because amid the billowy corn-fields of her mother demeter, and the meadow-flowers she loved in girlhood, are ever found sulphurous ravines, and chasms breathing vapour from the pit of hades."[ ] [ ] sketches in italy and greece, p. . it is said that both plato and the emperor hadrian ascended etna in order to witness the sunrise from its summit. the story of "he who to be deemed a god, leaped fondly into etna flames, empedokles" is too trite to need repetition. a ruined tower near the head of the val del bove, , feet above the sea, has from time immemorial been called the _torre del filosofo_, and is asserted to have been the observatory of empedokles. others regard it as the remains of a roman tower, which was possibly erected on the occasion of hadrian's ascent of the mountain. during the middle ages etna is frequently alluded to, among others by dante, petrarch, boccaccio, and cardinal bembo. the latter gives a description of the mountain in the form of a dialogue, which ferrara characterises as "_erudito, e grecizzante, ma sensa nervi_." he describes its general appearance, its well-wooded sides, and sterile summit. when he visited the mountain it had two craters about a stone's throw apart; the larger of the two was said to be about three miles in circumference, and it stood somewhat above the other.[ ] [ ] petri bembi de aetna. ad angelum chabrielem liber impressum venetiis aedibus aldi romani. mense februario anno m.v.d. ( ). in fazzello made an ascent of the mountain, which he briefly describes in the fourth chapter of his bulky volume _de rebus siculis_.[ ] this chapter is entitled "_de aetna monte et ejus ignibus_;" it contains a short history of the mountain, and some mention of the principal towns which he enumerates in the following order: catana, tauromenium, caltabianco, linguagrossa, castroleone, francavilla, rocella, randatio (randazzo), bronte, adrano, paterno, and motta. fazzello speaks of only one crater. [ ] fazzellus t. de rebus siculis. panormi, ; folio. in antonio filoteo, who was born on etna, published a work in venice in which he describes the general features of the mountain, and gives a special account of an eruption which he witnessed in .[ ] the mountain was then, as now, divided into three _regions_. the first and uppermost of these, he asserts, is very arid, rugged, and uneven, and full of broken rocks; the second is covered with forests; and the third is cultivated in the ordinary manner. of the height he remarks, "ascensum triginta circiter millia passuum ad plus habet." in regard to the name, _mongibello_, he makes a curious error, deriving it from _mulciber_, one of the names of vulcan, who, as we have seen, was feigned by the earlier poets to have had his forge within the mountain. [ ] antonii philothei de homodeis siculi, aetnÆ topographia, incendiorum aetnæorum historia. venetiis. . preface dated september, . in carrera gave an account of etna, followed by that of the jesuit kircher, in . the great eruption of was described at length by various eye-witnesses, and furnished the subject of the first detailed description of the eruptive phenomena of the mountain. public attention was now very generally drawn to the subject in all civilised countries. it was described by the naturalist, borelli, and in our own _philosophical transactions_. lord winchelsea, our ambassador at constantinople, was returning to england by way of the straits of messina at the time of the eruption, and he forwarded to charles ii "a true and exact relation of the late prodigious earthquake and eruption of mount Ætna, or monte gibello." the first map of the mountain which we have been able to meet with, was published in reference to the eruption of ; it is entitled, "plan du mont etna communenent dit mount gibel en l'isle de scicille et de t'incedie arrive par un treblement de terre le me mars dernier ." this plan is in the bibliothèque nationale, in paris; it was probably drawn from a simple description, or perhaps altogether from the imagination, as it is utterly unlike the mountain, the sides of which possess an impossible steepness. another very inaccurate map was published in nuremberg about , annexed to a map of sicily, which is entitled, "_regnorum siciliæ et sardiniæ, nova tabula_." again, in h. moll, "geographer in devereux street, strand," published a new map of italy, in which there is a representation of etna during the eruption of . this also was probably drawn from the imagination; no one who has ever seen the mountain would recognise it, for it has a small base, and sides which rival the matterhorn in abruptness. over against the coast of sicily, and near the mountain, is written:--"mount etna, or mount gibello. this mountain sometimes issues out pure flame, and at other times a thick smoak with ashes; streams of fire run down with great quantities of burning stones, and has made many eruptions." during the eighteenth century etna was frequently ascended, and as frequently described. we have the accounts of massa ( ), count d'orville ( ), riedesel ( ), sir william hamilton ( ), brydone ( ), houel ( ), dolomieu ( ), spallanzani ( ), and many minor writers, such as borch, brocchi, swinburne, denon, and faujas de saint fond. there is great sameness in all of these narratives, and much repetition of the same facts; some of them, however, merit a passing notice. sir william hamilton's _campi phlegræi_ relates mainly to vesuvius and the surrounding neighbourhood; but one of the letters "addressed to the secretary of the royal society on october th, ," describes an ascent of etna. hamilton ascended on june th with the canon recupero and other companions; the few observations of any value which he made have been alluded to elsewhere under the head of the special subjects to which they refer. the illustrations of the _campi phlegræi_, specially the original water-colours which are contained in one of the british museum copies, are magnificent, and convey a better idea of volcanic phenomena than any amount of simple reading. from them we can well realise the opening of a long rift extending down the sides of a mountain during its eruption, and the formation of subsidiary craters along the line of fire thus opened. various volcanic products are also admirably painted. in the picture of etna, however, which was drawn by antonio fabris, the artist has scarcely been more successful than his predecessors, and the slope of the sides of the mountain has been greatly exaggerated. m. houel, in his _voyage pittoresque dans les deux siciles_, - , has given a fairly good account of etna, accompanied by some really excellent engravings. in patrick brydone, a clever irishman with a good deal of native shrewdness and humour, published two volumes of a _tour in sicily and malta_, in which he devoted several chapters to mount etna. he made the ascent of the mountain, and collected from the canon recupero, and from others, many facts concerning its then present, and its past history. he also made observations as to the height, temperature of the air at various elevations, brightness of the stars, and so on. sir william hamilton calls brydone "a very ingenious and accurate observer," and adds that he was well acquainted with alpine measurements. m. elie de beaumont, writing in , speaks of him as _le celebre brydone_; while, on the other hand, the abbé spallanzani, displeased at certain remarks which he made concerning roman catholicism in sicily, never fails to deprecate his work, and deplores "his trivial and insipid pleasantries." albeit brydone's chapters on etna furnished a more complete account of the volcano than any which had appeared in english up to that time; his remarks are frequently very sound and just, and we shall have occasion more than once to quote him. it was reserved, however, for the abate francesco ferrara, professor of physical science in the university of catania, to furnish the first history of etna and of its eruptions, which had any just claim to completeness. it is entitled, _descrizione dell' etna, con la storia delle eruzioni e il catalogo del prodotti_. the first edition appeared in , and a second was printed in palermo in . the author had an enthusiastic love for his subject:--"nato sopra l'etna," he writes, "che io conobbi ben presto palmo a palmo la mia passione per lo studio fissò la mia attenzione sul bello, e terribile fenomeno che avea avanti agli occhi." the work commences with a general description of the mountain--its height, the temperature of the different regions, the view from the summit, the mass, the water-springs, the vegetable and animal life, and the internal fires. this extends over sixty-nine octavo pages. the second part of the book--eighty pages--gives a history of the eruptions from the earliest times to the year ; the third part--sixty-seven pages--treats of the nature of the volcanic products; and the fourth part--thirty-four pages--discusses certain geological and physical considerations concerning the mountain. at the end there are a few badly drawn and engraved woodcuts, and a map which, although the trend of the coast-line is quite wrong, is otherwise fairly good. the engravings represent the mountain as seen from catania; the isole dei ciclopi, and the neighbouring coast; the montagna della motta; and a view from catania of the eruption of . this work has evidently to a great extent been a labour of love; it is full of personal observations, and also embodies the results of many other observers. it has furnished the foundation of much that has since been written concerning etna. the canon recupero has been alluded to above; he accompanied hamilton, brydone, and others to the summit of the mountain, and he was employed by the government to report on the flood which, in , descended with extraordinary violence through the val del bove. beyond this, recupero does not appear to have published anything concerning etna, although it was well known that he had plenty of materials. he died in , and it was not till the year that his results were published under the title of _storia naturale et generale dell' etna, del canonico giuseppe recupero.--opera postuma_. this work consists of two bulky quarto volumes, the first of which is devoted to a general description of the mountain, the second to a history of the eruptions, and an account of the products of eruptions. some idea may be formed of the extreme prolixity of the author if we mention that two chapters, together containing twelve quarto pages, are devoted to the discussion of the height of etna, while the first volume is terminated by sixty-three closely printed pages of annotations. a few rough woodcuts accompany the volumes; a view of the mountain which, as usual, is out of all reason as regards abruptness of ascent, and a _carta oryctographia di mongibello_ in which the trend of the coast-line between catania and taormina is altogether inexact, complete the illustrations of this most detailed of histories. during the years - captain smyth, acting under orders from the admiralty, made a survey of the coast of sicily, and of the adjacent islands. at this time the mediterranean charts were very defective; some places on the coast of sicily were mapped as much as twenty miles out of their true position, and even the exact positions of the observatories at naples, palermo, and malta were not known. among other results, smyth carefully determined the latitude and longitude of etna, accurately measured its height, and examined the surroundings of the mountain. his results were published in , and are often regarded as the most accurate that we possess. in dr. joseph gemellaro, who lived all his life on the mountain, and made it his constant study, published an "historical and topographical map of the eruptions of etna from the era of the sicani to the year ." in it he delineates the extent of the three regions, _coltivata_, _selvosa_, and _deserta_; he places the minor cones, to the number of seventy-four, in their proper places, and he traces the course of the various lava-streams which have flowed from them and from the great crater. this map is the result of much patient labour and study, and it is a great improvement upon those of ferrara and recupero, but of course it is impossible for one man to survey with much accuracy an area of nearly square miles, and to trace the tortuous course of a large number of lava-streams. hence we must be prepared for inaccuracies, and they are not uncommon--the coast line is altogether wrong as to its bearings, some of the small towns on the sides of the mountain are misplaced, and but little attention has been paid to scale. still the map is very useful, as it is the only one which shows the course of the lava-streams. mario gemellaro, brother of the preceding, made almost daily observations of the condition of etna, between the years and . these results were tabulated, and they are given in the _vulcanologia dell' etna_ of his brother, professor carlo gemellaro, under the title of _registro di osservazioni del sigr. mario gemellaro_. carlo gemellaro contributed many memoirs on subjects connected with the mountain. they are chiefly to be found in the _atti dell' accademia gioenia_ of catania, and they extend over a number of years. perhaps the most important is the treatise entitled "_la vulcanologia dell' etna che comprende la topographia, la geologia, la storia, delle sue eruzioni_." it was published in catania in , and is dedicated to sir charles lyell, who ascended the mountain under the guidance of the author. the latter also published a _breve raggualio della eruzione dell' etna, del agosto _, which contains the most authentic account of this important eruption, accompanied by some graphic sketches made on the spot. the last contribution of carlo gemellaro to the history of etna, is fitly entitled _un addio al maggior vulcano di europa_. it was published in , and with pardonable vanity the author reviews his work in connection with the mountain, extending over a period of more than forty years. he commences his somewhat florid farewell with the following apostrophe:--"o etna! splendida e perenne manifestazione della esistenza dei fuochi sotteranei massimo fra quanti altri monti, dalle coste meridionali di europa, dalle orientali dell' asia e delle settentrionali dell' africa si specchiano nel mediterraneo: tremendo pei tuoi incendii: benigno per la fertilità del vulcanico tuo terreno ridotto a prospera coltivazione ... io, nato appiè del vasto tuo cono, in quella città che hai minacciato più d'una volta di sepellire sotto le tue infocate correnti: allogato, nella mia prima età, in una stanza della casa paterna, che signoreggiava in allora più basse abizioni vicine, ed intiera godeva la veduta della estesa parte meridionalè della tua mole, io non potera non averti di continuo sotto gli occhi, e non essere spettatore dei tuoi visibili fenomeni!" in , m. elie de beaumont commenced a minute geological examination of the mountain. his results were published in , under the title of _recherches sur la structure et sur l'origine du mont etna_, and they extend over pages.[ ] he re-determined the latitude and longitude of the mountain, measured the slope of the cone, and the diameter of the great crater, and minutely examined the structure of the rocks at the base of the mountain. he also gives a good sectional view, elevations taken from each quarter of the compass, and a geological map, which although accurate in its general details, can scarcely be considered very satisfactory. a relief map of etna, a copy of which is in the royal school of mines, was afterwards constructed from the flat map, and this was, we believe, at the same time, the first geological map, and the first map in relief, which had been made of the mountain. elie de beaumont considers granite as the basis of the mountain, because it is sometimes ejected from the crater; old basaltic rocks appear in the isole dei ciclopi, and near paterno, licodia, and aderno; _cailloux roulés_ near motta; ancient lavas on each side of the val del bove; modern lavas in every part of the mountain, and calcareous and arenaceous rocks in the surrounding mountains. [ ] printed in vol. iv. of _mémoires pour servir a une description geologique de la france_. par m.m. dufrénoy et elie de beaumont. in , abich published some excellent sections of etna, and an accurate view of the interior of the crater, in a work entitled _vues illustratives de quelques phénomènes géologiques prises sur le vésuve et l'etna pendant les années and _. the whole of the thirteenth volume ( ) of the berlin _archiv für mineralogie, geognosie, berghau und hüttenkunde_, is occupied by an elaborate memoir on the geology of sicily[ ] by friedrich hoffmann, accompanied by an excellent geological map. a long account of the geology of etna is given, and an enlarged map of the mountain was afterwards constructed and published in the _vulkanen atlas_ of dr. leonhard in .[ ] [ ] entitled _geognostiche beobachtungen gesammelt auf einer reise durch italian und sicilien, in den jahren bis , von friedrich hoffmann_. [ ] _vulkanen atlas zur naturgeschichte der erde von k. g. von leonhard._ stuttgardt. . in baron sartorius von waltershausen commenced a minute survey of etna, preparatory to a complete description of the mountain, both geological and otherwise. he was assisted by professor cavallari of palermo, professor peters of hensbourg, and professor roos of mayence. the survey occupied six years, ( - ), and the results of direct observation in the form of maps and drawings, occupied a hundred sheets millimetres ( - / inches) long, by m.m. ( - / inches) broad. twenty-nine separate points were made use of in the triangulation; and the scale chosen was in , . the results were published in a large folio atlas, which appeared in eight parts; the first in and the last in , when the death of von waltershausen put an end to the further publication. there are fine coloured maps, and engravings. the cost of the atlas is £ . the maps are both geological and topographical, and they are accompanied by outline engravings of various details of special interest. the _atlas des aetna_ furnishes the most exhaustive history of any one mountain on the face of the earth, and sartorius von waltershausen will always be the principal authority on the subject of etna. sir charles lyell visited etna in , , and again in . he embodied his researches in a paper presented to the royal society in , and in a lengthy chapter in the _principles of geology_. his investigations have added much to our knowledge of the formation and geological characteristics of the mountain, especially of that part of it called the val del bove. later writers usually quote von waltershausen and lyell, and do not add much original matter. the facts of all subsequent writers are taken more or less directly from these authors. the latest addition to the literature of the mountain, is the _wanderungen am aetna_ of dr. baltzer, in the journal of the swiss alpine club for .[ ] [ ] jahrbuch des schweizer alpen club. neunter jahrgang, - . bern . a fine map of sicily, on the unusually large scale of in , , or · inch to a mile, was constructed by the stato maggiore of the italian government, between and . the portion relating to etna, and its immediate surroundings occupies four sheets. all the small roads and rivulets are introduced; the minor cones and monticules are placed in their proper positions, and the elevation of the ground is given at short intervals of space over the entire map. an examination of this map shows us that distances, areas, and heights, have been repeatedly misstated, the minor cones misplaced, and the trend of the coast line misrepresented. for example, if we draw a line due north and south through catania, and a second line from the capo di taormina, (the north-eastern limit of the base of etna), until it meets the first line at catania, the lines, will be found to enclose an angle of °. if we adopt the same plan with gemellaro's map, the included angle is found to be °, and in the case of the maps of ferrara and recupero more than °. again, it has been stated on good authority, that the lava of b.c. which enters the sea at capo di schiso flowed for a distance of nearly miles; the map shows us that its true course was less than miles. lyell in gives a section of the mountain from west ° n., to east ° s., but a comparison with the new map proves that the section is really taken from west ° n. to east ° s., an error which at a radius of ten miles from the crater would amount to a difference of nearly three miles. the mantle of carlo gemellaro appears to have fallen upon cav. orazio silvestri, professor of chemistry in the university of catania. he has devoted himself with unwearying vigour to the study of the mountain, and his memoirs have done much to elucidate its past and present history. his most recent work of importance on the subject is entitled _i fenomeni vulcanici presentati dall'etna nel - - - _. it was published in catania in , and contains an account of some very elaborate chemico-geological researches. chapter ii. physical features of the mountain. height.--radius of vision from the summit.--boundaries.--area.-- population.--general aspect of etna.--the val del bove.--minor cones.--caverns.--position and extent of the three regions.--regione coltivata.--regione selvosa.--regione deserta.--botanical regions.-- divisions of rafinesque-schmaltz, and of presl.--animal life in the upper regions. in the preceding chapter we have discussed the history of mount etna; the references to its phenomena afforded by writers of various periods; and the present state of the literature of the subject. we have now to consider the general aspect and physical features of the mountain, together with the divisions of its surface into distinct regions. the height of etna has been often determined. the earlier writers had very extravagant notions on the subject, and three miles has sometimes been assigned to it. brydone, saussure, shuckburgh, irvine, and others, obtained approximations to the real height; it must be borne in mind, however, that the cone of a volcano is liable to variations in height at different periods, and a diminution of as much as feet occurred during one of the eruptions of etna, owing to the falling in of the upper portion of the crater. during the last sixty years, however, the height of the mountain has been practically constant. in captain smyth determined it to be , feet. in sir john herschel, who was unacquainted with smyth's results, estimated it at , - / feet. the new map of the stato maggiore gives · metres = · feet. when the canon recupero devoted two chapters of his quarto volume to a discussion of the height of etna, no such exact observations had been made, consequently he compared, and critically examined, the various determinations which then existed. the almost perfect concordance of the results given by smyth, herschel, and the stato maggiore, render it unnecessary for us to further discuss a subject about which there can now be no difference of opinion. professor jukes says, "if we were to put snowdon, the highest mountain in wales, on the top of ben nevis, the highest in scotland, and carrantuohill, the highest in ireland, on the summit of both, we should make a mountain but a very little higher than etna, and we should require to heap up a great number of other mountains round the flanks of our new one in order to build a gentle sloping pile which should equal etna in bulk." the extent of radius of vision from the summit of etna is very variously stated. the exaggerated notions of the earlier writers, that the coast of africa and of greece are sometimes visible, may be at once set aside. lord ormonde's statement that he saw the gulf of taranta, and the mountains of terra di lecce beyond it--a distance of miles--must be received with caution. it is, however, a fact that malta, miles distant, is often visible; and captain smyth asserts that a considerable portion of the upper part of the mountain may sometimes be seen, and that he once saw more than half of it, from malta, although that island is usually surrounded by a sea-horizon. it is stated on good authority that monte s. giuliano above trapani, and the oegadean isles, miles distant, are sometimes seen. other writers give miles as the limit. the fact is, that atmospheric refraction varies so much with different conditions of the atmosphere that it is almost impossible to give any exact statement. the more so when we remember that there may be many layers of atmosphere of different density between the observer and the horizon. distant objects seem to be just under one's feet when seen from the summit of the mountain. smyth gives the radius of vision as · miles: and this we are inclined to adopt as the nearest approach to the truth, because smyth was an accurate observer, and he made careful corrections both for error of instruments and for refraction. this radius gives an horizon of · miles of circumference, and an included area of , square miles--larger than the area of ireland. if a circle be traced with the crater of etna as a centre, and a radius of · miles, it will be found to take in the whole of sicily and malta, to cut the western coast of italy at scalca in calabria, leaving the south-east coast near cape rizzuto. such a circle will include the whole of ireland, or if we take derby as the centre, its circumference will touch the sea beyond yarmouth on the east, the isle of wight on the south, the irish channel on the west, and it will pass beyond carlisle and newcastle-on-tyne on the north. the road which surrounds the mountain is carried along its lower slopes, and is miles in length. it passes through the towns of paterno, aderno, bronte, randazzo, linguaglossa, giarre, and aci reale. it is considered by some writers to define the base of the mountain, which is hence most erroneously said to have a circumference of miles; but the road frequently passes over high beds of lava, and winds considerably. it is about miles from the crater on the north, east, and west sides, increasing to - / miles at paterno, (s.w.). the elevation on the north and west flanks of the mountain is nearly , feet, while on the south it falls to , feet, and on the east to within feet of the level of the sea. it is quite clear that it cannot be asserted with any degree of accuracy to define the base of the mountain. [illustration: sections of etna] the "natural boundaries" of etna are the rivers alcantara and simeto on the north, west, and south, and the sea on the east to the extent of miles of coast, along which lava streams have been traced, sometimes forming headlands several hundred feet in height. the base of the mountain, as defined by these natural boundaries, is said to have a circumference of "at least miles," an examination of the new map, however, proves that this is over-estimated. if we take the sea as the eastern boundary, the river alcantara, (immediately beyond which monte di mojo, the most northerly minor cone of etna is situated), as the northern boundary, and the river simeto as the boundary on the west and south, we obtain a circumference of miles for the base of etna. in this estimate the small sinuosities of the river have been neglected, and the southern circuit has been completed by drawing a line from near paterno to catania, because the simeto runs for the last few miles of its course through the plain of catania, quite beyond the most southerly stream of lava. the simeto (anciently _simæthus_) is called the giaretta along the last three miles of its course, after its junction with the gurna longa. the area of the region enclosed by these boundaries is approximately square miles. reclus gives the area of the mountain as , square kilometres-- square miles. (_nouvelle geographie universelle_, .) the last edition of a standard gazetteer states it as " square miles;" but this estimate is altogether absurd. this would require a circle having a radius of between sixteen and seventeen miles. if a circle be drawn with a radius of sixteen miles from the crater, it will pass out to sea to a distance of - / miles on the east, while on the west and north it will pass through limestone and sandstone formations far beyond the alcantara and the simeto, and beyond the limit of the lava streams. there are two cities, catania and aci reale, and sixty-two towns or villages on mount etna. it is far more thickly populated than any other part of sicily or italy, for while the population of the former is per square mile, and of the latter , the population of the habitable zone of etna amounts to , per square mile. more than , persons live on the slopes of the mountain. thus with an area rather larger than that of bedfordshire ( square miles) the mountain has more than double the population; and with an area equal to about one-third that of wiltshire, the population of the mountain is greater by nearly , inhabitants. we have stated above that the area of etna is square miles, but it must be borne in mind that the habitable zone only commences at a distance of about - / miles from the crater. a circle, having a radius of - / miles, encloses an area of square miles; and minus leaves square miles as the approximate area of the habitable zone. only a few insignificant villages on the east side are nearer to the crater than - / miles. taking the inhabitants as , , we find, by dividing this number by , (the area of the habitable zone), that the population amounts to , per square mile. even lancashire, the most populous county in great britain, (of course excepting middlesex), and the possessor of two cities, which alone furnish more than a million inhabitants, has a population of only , to the square mile. some idea of the closeness of the towns and villages may be found by examining the south-east corner of the map. if we draw a line from aci reale to nicolosi, and from nicolosi to catania, we enclose a nearly equilateral triangle, having the coast line between aci reale and catania as its third side. starting from aci reale with , inhabitants, and moving westwards to nicolosi, we come in succession to aci s. lucia, aci catena, aci s. antonio, via grande, tre castagni, pedara, nicolosi, completing the first side of the triangle; then turning to the south-east and following the catania road, we pass torre di grifo, mascalucia, gravina, and reach catania with , inhabitants; while on the line of coast between catania and aci reale we have ognina, aci castello, and trezza. within the triangle we find aci patane, aci s. filippo, valverde, bonacorsi, s. gregorio, tremestieri, piano, s. agata, trappeto, and s. giovanni la punta: in all twenty-five, two of which are cities, several of the others towns of about , inhabitants, and the rest villages. these are all included within an area of less than thirty square miles, which constitutes the most populous portion of the habitable zone of etna. that the population is rapidly increasing is well shown by a comparison of the number of inhabitants of some of the more important towns in and in .[ ] _ _ _ _ catania , , aci reale , , giarre , , paternò , , aderno , , bronte , , biancavilla , , linguaglossa , , randazzo , , piedimonte etnea , , zaffarana etnea , pedara , , trecastagni , , [ ] i am indebted for these figures to mr. george dennis, h.m. consul general for sicily. the general aspect of etna is that of a pretty regular cone, covered with vegetation, except near the summit. the regularity is broken on the east side by a slightly oval valley, four or five miles in diameter, called the _val del bove_, or in the language of the district val del _bue_. this commences about two miles from the summit, and is bounded on three sides by nearly vertical precipices from , to , feet in height. the bottom of the valley is covered with lavas of various date, and several minor craters have from time to time been upraised from it. many eruptions have commenced in the immediate neighbourhood of the val del bove, and lyell believes that there formerly existed a centre of permanent eruption in the valley. the val del bove is altogether sterile; but the mountain at the same level is, on other sides, clothed with trees. the vast mass of the mountain is realised by the fact that, after twelve miles of the ascent from catania, the summit looks as far off as it did at starting. moreover, mount vesuvius might be almost hidden away in the val del bove. a remarkable feature of etna is the large number of minor craters which are scattered over its sides. they look small in comparison with the great mass of the mountain, but in reality some of them are of large dimensions. monte minardo, near bronte, the largest of these minor cones, is still feet high, although its base has been raised by modern lava-streams which have flowed around it. there are of the more conspicuous of these minor cones, but von waltershausen has mapped no less than within a ten mile radius from the great crater, while neglecting many monticules of ashes. as to the statement made by reclus to the effect that there are minor cones, and by jukes, that the number is , it is to be supposed that they include not only the most insignificant monticules and heaps of cinders, but also the _bocche_ and _boccarelle_ from which at any time lava or fire has issued. if these be included, no doubt these numbers are not exaggerations. [illustration: grotto delle palombe] the only important minor cone which has been produced during the historical period, is the double mountain known as monti rossi, from the red colour of the cinders which compose it. this was raised from the plain of nicolosi during the eruption of ; it is feet in height, and two miles in circumference at the base. in a line between the monti rossi and the great crater, thirty-three minor cones may be counted. hamilton counted forty-four, looking down from the summit towards catania, and captain smyth was able to discern fifty at once from an elevated position on the mountain. many of these parasitic cones are covered with vegetation, as the names monte faggi, monte ilice, monte zappini, indicate. the names have not been happily chosen; thus there are several cones in different parts of the mountain called by the same name--monte arso, monte nero, monte rosso, monte frumento, are the most common of the duplicates. moreover, the names have from time to time been altered, and it thus sometimes becomes difficult to trace a cone which has been alluded to under a former name, or by an author who wrote before the name was changed. in addition to the minor cones from which lava once proceeded, there are numerous smaller vents for the subterranean fires called _bocche_, or if very small, _boccarelle_, _del fuoco_. in the eruption of , thirteen mouths opened in the course of a few days; and in the eruption of , twenty new mouths opened one after the other in a line about six miles long. two new craters were formed in the val del bove in , and seven craters in . the outbursts of lava from lateral cones are no doubt due to the fact that the pressure of lava in the great crater, which is nearly feet in depth, becomes so great that the lava is forced out at some lower point of less resistance. the most northerly of the minor cones is monte di mojo, from whence issued the lava of b.c., it is - / miles from the crater; the most southerly cone is monte ste sofia, miles from the crater. nearly all the minor cones are within miles of the crater, and the majority are collected between south-east, and west, that is, in an angular space of °, starting midway between east and south, ( ° south of due east) to due west, ( ° west of due south). lyell speaks of the minor cones "as the most grand and original feature in the physiognomy of etna." a number of caverns are met with in various parts of etna; boccacio speaks of the cavern of thalia, and several early writers allude to the grotto delle palombe near nicolosi. the latter is situated in front of monte fusara, and the entrance to it is evidently the crater of an extinct monticule. it descends for feet, and at the bottom a cavern is entered by a long shaft; this leads to a second cavern, which abruptly descends, and appears to be continued into the heart of the neighbouring monti rossi. brydone says that people have lost their senses in these caverns, "imagining that they saw devils, and the spirits of the damned; for it is still very generally believed that etna is the mouth of hell." many of the caverns near the upper part of the mountain are used for storing snow, and sometimes as places of shelter for shepherds. we have already seen to what extent lucretius attributed the eruptions to air pent up within the interior caverns of the mountains. the surface of the mountain has been divided into three zones or regions--the _piedimontana_ or _coltivata_; the _selvosa_ or _nemorosa_; and the _deserta_ or _discoperta_. sometimes the name of _regione del fuoco_ is given to the central cone and crater. as regards temperature, the zones correspond more or less to the torrid, temperate, and frigid. the lowest of these, the _cultivated region_, yields in abundance all the ordinary sicilian products. the soil, which consists of decomposed lava, is extremely fertile, although of course large tracts of land are covered by recent lavas, or by those which decompose slowly. in this region the vine flourishes, and abundance of corn, olives, pistachio nuts, oranges, lemons, figs, and other fruit trees. the breadth of this region varies; it terminates at an approximate height of feet. a circle drawn with a radius of miles from the crater, roughly defines the limit. the elevation of this on the north is , feet near randazzo; on the south, , feet near nicolosi; on the east, feet near mascali; and on the west, , feet near bronte. the breadth of this cultivated zone is about miles on the north, east, and west, and or on the south, if we take for the base of the mountain the limits proposed above. the _woody region_ commences where the cultivated region ends, and extends as a belt of varying width to an approximate height of , feet. it is terminated above by a circle having a radius of nearly - / miles from the crater. there are fourteen separate forests in this region: some abounding with the oak, beech, pine, and poplar, others with the chestnut, ilex, and cork tree. the celebrated _castagno di cento cavalli_, one of the largest and oldest trees in the world, is in the forest of carpinetto, on the east side of the mountain, five miles above giarre. this tree has the appearance of five separate trunks united into one, but ferrara declares that by digging a very short distance below the surface he found one single stem. the public road now passes through the much-decayed trunk. captain smyth measured the circumference a few feet from the ground, and found it to be feet, which would give it a diameter of more than feet. the tree derives its name from the story that one of the queens of arragon took shelter in its trunk with a suite of horsemen. near this patriarch are several large chestnuts, which, without a shadow of doubt, are single trees; one of these is feet in diameter, and a second feet, while the _castagno della galea_, higher up on the mountain, is feet in diameter, and probably more than years old. the breadth of the regione selvosa varies considerably, as may be seen by reference to the accompanying map; in the direction of the val del bove it is very narrow, while elsewhere it frequently has a breadth of from to miles. the desert region is embraced between the limit of , feet and the summit. it occupies about square miles, and consists of a dreary waste of black sand, scoriæ, ashes, and masses of ejected lava. in winter it remains permanently covered with snow, and even in the height of summer snow may be found in certain rifts. botanists have divided the surface of etna into seven regions. the first extends from the level of the sea to feet above it, and in it flourishes the palm, banana, indian fig or prickly pear, sugar-cane, mimosa, and acacia. it must be remembered, however, that it is only on the east side of the mountain that the level within the base sinks to feet above the sea; and, moreover, that the palm, banana, and sugar-cane, are comparative rarities in this part of sicily. prickly pears and vines are the most abundant products of the lower slopes of the eastern side of etna. the second, or hilly region, reaches from to feet above the sea, and therefore constitutes, with the preceding, the _regione coltivata_ of our former division. in it are found cotton, maize, orange, lemon, shaddock, and the ordinary sicilian produce. the culture of the vine ceases near its upward limit. the third, or woody region, reaches from to feet, and the principal trees within it are the cork, oak, maple, and chestnut. the fourth region extends from to feet, and contains the beech, scotch fir, birch, dock, plaintain, and sandworth. the fifth, or sub-alpine region, extending from to feet, contains the barberry, soapwort, toad-flax, and juniper. in the sixth region, , to feet, are found soapwort, sorrel, and groundsel; while the last narrow zone, to , feet, contains a few lichens, the commonest of which is the _stereocaulon paschale_. the flora of etna comprises species, only of which are found between feet and the summit, while in the last feet only five phanerogamous species are found, viz., anthemis etnensis, senecio etnensis, robertsia taraxacoides, (which are peculiar to etna), tanacetum vulgare, and astragulus siculus. common ferns, such as the _pteris aquilina_, are found in abundance beneath the trees in the regione selvosa. this division has been advocated by presl in his _flora sicula_.[ ] he names the different regions beginning from below: _regio subtropica_, _regio collina_, _regio sylvatica inferior_, _regio fagi sylvestris_. these four are common to all sicily. the three remaining regions, _regio subalpina_, _regio alpina_, and _regio lichenum_, together extending from to , feet, belong to etna alone. [ ] "flora sicula: exhibens plantas vasculosas in sicilia aut sponte crescentes aut frequentissime cultas, secundum systema naturale digestas." auctore g. b. presl. pragæ, . at the conclusion of the first volume of recupero's _storia naturale et generale dell' etna_ we find a somewhat different botanical division proposed by signor rafinesque-schmaltz.[ ] he makes his divisions in the following manner:-- . florula piedemontana. . florula nemorosa. . florula excelsa o della regione discoperta. . florula arenosa o della regione delle scorie. [ ] chloris aetnensis: o le quattro florule dell' etna, opusculo del sig. c. s. rafinesque-schmaltz, palermo. dicembre, . in the latter region, (to which he assigns no limit as to height), he found potentilla argentea, rumex scutatus, tanacetum vulgare, anthemis montana, jacobæa chrysanthemifolia, seriola uniflora, and phalaris alpina. as regards the animal life on etna, of course it is the same as that of the eastern sea-board of sicily, except in the higher regions, where it becomes more sparse. the only living creatures in the upper regions are ants, a little lower down spallanzani found a few partridges, jays, thrushes, ravens, and kites. brydone says of the three regions: "besides the corn, the wine, the oil, the silk, the spice, and delicious fruits of its lower region; the beautiful forests, the flocks, the game, the tar, the cork, the honey of its second; the snow and ice of its third; it affords from its caverns a variety of minerals and other productions--cinnabar, mercury, sulphur, alum, nitre, and vitriol; so that this wonderful mountain at the same time produces every necessary, and every luxury of life." chapter iii. ascent of the mountain. the most suitable time for ascending etna.--the ascent commenced.-- nicolosi.--etna mules.--night journey through the upper regions of the mountain.--brilliancy of the stars.--proposed observatory on etna.--the casa inglesi.--summit of the great crater.--sunrise from the summit.--the crater.--descent from the mountain.--effects of refraction.--fatigue of the ascent. the ascent of mount etna has been described many times during the last eighteen centuries, from strabo in the second century to dr. baltzer in . one of the most interesting accounts is certainly that of brydone, and in this century perhaps that of mr. gladstone. of course the interest of the expedition is greatly increased if it can be combined with that spice of danger which is afforded by the fact of the mountain being in a state of eruption at the time. the best period for making the ascent is between may and september, after the melting of the winter snows, and before the autumnal rains. in winter snow frequently extends from the summit downwards for nine or ten miles; the paths are obliterated, and the guides refuse to accompany travellers. even so late in the spring as may th brydone had to traverse seven miles of snow before reaching the summit. moreover, violent storms often rage in the upper regions of the mountain, and the wind acquires a force which it is difficult to withstand, and is at the same time piercingly cold. sir william hamilton, in relating his ascent on the night of june th, , remarks that, if they had not kindled a fire at the halting place, and put on much warm clothing, they would "surely have perished with the cold." at the same time the wind was so violent that they had several times to throw themselves on their faces to avoid being overthrown. yet the guides said that the wind was not unusually violent. some writers, well used to alpine climbing, have asserted that the cold on etna was more severe than anything they have ever experienced in the alps. the writer of this memoir made the ascent of the mountain in august , accompanied by a courier and a guide. we took with us two mules; some thick rugs; provisions consisting of bread, meat, wine, coffee, and brandy; wooden staves for making the ascent of the cone; a geological hammer; a bag for specimens; and a few other requisites. it has to be remembered that absolutely nothing is to be met with at the casa inglesi, where the halt is made for the night; even firewood has to be taken, a fire being most necessary in those elevated regions even during a midsummer's night. for some time previous to our ascent the weather had been uniformly bright and fine, and there had been no rain for more than three months. the mean temperature in the shade at catania, and generally along the eastern sea-base of the mountain, was ° f. as we desired to see the sunrise from the summit of the mountain, we determined to ascend during the cool of the evening, resting for an hour or two before sunrise at the casa inglesi at the foot of the cone. accordingly we left catania soon after midday, and drove to nicolosi, twelve miles distant, and , feet above the sea. the road for some distance passed through a very fertile district; on either side there were corn fields and vineyards, and gardens of orange and lemon trees, figs and almonds, growing luxuriantly in the decomposed lava. about half way between catania and nicolosi stands the village of gravina, and a mile beyond it mascalucia, a small town containing nearly inhabitants. near this is the ruined church of st. antonio, founded in . nine miles from catania the village of torre di grifo is passed, and the road then enters a nearly barren district covered with the lava and scoriæ of . the only prominent form of vegetation is a peculiar tall broom--_genista etnensis_--which here flourishes. we are now entering the region of minor cones; the vineclad cone of monpilieri is visible on the left, and just above it monti rossi, , feet above the sea; to the right of the latter we see monte san nicola, serrapizzuta, and monte arso. we reach nicolosi at half-past four; for although the distance is short, the road is very rugged and steep. nicolosi has a population of less than , ; it consists of a long street, bordered by one-storied cottages of lava. in the church the priests were preparing for a _festa_ in honour of s. anthony of padua. they politely took us into the sacristy, and exhibited with much pride some graven images of rather coarse workmanship, which were covered with gilding and bright coloured paint. near nicolosi stands the convent of s. nicola dell' arena, once inhabited by benedictine monks, who however were compelled to abandon it in consequence of the destruction produced by successive shocks of earthquake. nicolosi itself has been more than once shaken to the ground. we dined pretty comfortably, thanks to the courier who acted as cook, in the one public room of the one primitive inn of the town; starting for the casa inglesi at o'clock. the good people of the inn surrounded us at our departure and with much warmth wished us a safe and successful journey. for a short distance above nicolosi, stunted vines are seen growing in black cinders, but these soon give place to a large tract covered with lava and ashes, with here and there patches of broom. there was no visible path, but the mules seemed to know the way perfectly, and they continued to ascend with the same easy even pace without any guidance, even after the sun had disappeared behind the western flank of the mountain. in fact, you trust yourself absolutely to your mule, which picks his way over the roughest ground, and rarely stumbles or changes his even step. i found it quite easy to write notes while ascending, and even to use a pocket spectroscope at the time of the setting sun. subsequently we saw a man extended at full length, and fast asleep upon a mule, which was leisurely plodding along the highway. the same confidence must not however be extended to the donkeys of etna, as i found to my cost a few days later at taormina. here the only animal to be procured to carry me down to the sea-shore, feet below, was a donkey. it was during the hottest part of the day, and it was necessary to carry an umbrella in one hand, and comfortable to wear a kind of turban of many folds of thin muslin round one's cap. the donkey after carefully selecting the roughest and most precipitous part of the road, promptly fell down, leaving me extended at full length on the road, with the open umbrella a few yards off. at the same time the turban came unfolded, and stretched itself for many a foot upon the ground. altogether it was a most comical sight, and it reminded me forcibly, and at the instant, of a picture which i once saw over the altar of a church in pisa, and which represented s. thomas aquinas discomfiting plato, aristotle, and averröes. the latter was completely overthrown, and in the most literal sense, for he was grovelling in the dust at the feet of s. thomas, while his disarranged turban had fallen from him. the district of lava and ashes above nicolosi is succeeded by forests of small trees, and we are now fairly within the _regione selvosa_. at half-past o'clock the temperature was °, at nicolosi at o'clock it was °. about o'clock we arrived at the casa del bosco, ( , feet), a small house in which several men in charge of the forest live. here we rested till o'clock, and then after i had put on a great-coat and a second waistcoat, we started for the higher regions. at this time the air was extraordinarily still, the flame of a candle placed near the open door of the house did not flicker. the ascent from this point carried us through forests of pollard oaks, in which it was quite impossible to see either a path or any obstacles which might lie in one's way. the guide carried a lantern, and the mules seemed well accustomed to the route. at about , feet we entered the _regione deserta_, a lifeless waste of black sand, ashes, and lava; the ascent became more steep, and the air was bitterly cold. there was no moon, but the stars shone with an extraordinary brilliancy, and sparkled like particles of white-hot steel. i had never before seen the heavens studded with such myriads of stars. the milky-way shone like a path of fire, and meteors flashed across the sky in such numbers that i soon gave up any attempt to count them. the vault of heaven seemed to be much nearer than when seen from the earth, and more flat, as if only a short distance above our heads, and some of the brighter stars appeared to be hanging down from the sky. brydone, in speaking of his impressions under similar circumstances says: "the sky was clear, and the immense vault of heaven appeared in awful majesty and splendour. we found ourselves more struck with veneration than below, and at first were at a loss to know the cause, till we observed with astonishment that the number of the stars seemed to be infinitely increased, and the light of each of them appeared brighter than usual. the whiteness of the milky-way was like a pure flame that shot across the heavens, and with the naked eye we could observe clusters of stars that were invisible in the regions below. we did not at first attend to the cause, nor recollect that we had now passed through ten or twelve thousand feet of gross vapour, that blunts and confuses every ray before it reaches the surface of the earth. we were amazed at the distinctness of vision, and exclaimed together, 'what a glorious situation for an observatory! had empedocles had the eyes of galileo, what discoveries must he not have made!' we regretted that jupiter was not visible, as i am persuaded we might have discovered some of his satellites with the naked eye, or at least with a small glass which i had in my pocket." brydone wrote a hundred years ago, but his idea of erecting an observatory on mount etna was only revived last year, when prof. tacchini the astronomer royal at palermo, communicated a paper to the accademia gioenia, entitled "_della convenienza ed utilita di erigere sull' etna una stazione astronomico-meteorologico_." tacchini mentions the extraordinary blueness of the sky as seen from etna, and the appearance of the sun, which is "whiter and more tranquil" than when seen from below. moreover, the spectroscopic lines are defined with wonderful distinctness. in the evening at o'clock, sirius appeared to rival venus, the peculiarities of the ring of saturn were seen far better than at palermo; and venus emitted a light sufficiently powerful to cast shadows; it also scintillated. when the chromosphere of the sun was examined the next morning by the spectroscope, the inversion of the magnesium line, and of the line was immediately apparent, although it was impossible to obtain this effect at palermo. tacchini proposes that an observatory should be established at the casa inglesi, in connection with the university of catania, and that it be provided with a good six-inch refracting telescope, and with meteorological instruments. in this observatory, constant observations should be made from the beginning of june to the end of september, and the telescope should then be transported to catania, where a duplicate mounting might be provided for it, and observations continued for the rest of the year. there seems to be every probability that this scheme will be carried out in the course of next year. during this digression we have been toiling along the slopes of the _regione deserta_ and looking at the sky; at length we reach the _piano del lago_ or plain of the lake, so called because a lake produced by the melting of the snows existed here till , when it was filled up by lava. the air is now excessively cold, and a sharp wind is blowing. progress is very slow, the soil consists of loose ashes, and the mules frequently stop; the guide assures us that the casa inglesi is quite near, but the stoppages become so frequent that it seems a long way off; at length we dismount, and drag the mules after us, and after a toilsome walk the small lava-built house, called the casa inglesi, is reached ( . a.m., temperature ° f.) it stands at a height of , feet above the sea, near the base of the cone of the great crater, and it takes its name from the fact that it was erected by the english officers stationed in sicily in . it has suffered severely from time to time from the pressure of snow and from earthquakes, but it was thoroughly repaired in , on the occasion of the visit of prince humbert, and is now in tolerable preservation. it consists of three rooms, containing a few deal chairs, a table, and several shelves like the berths of ships furnished with plain straw mattresses; there is also a rough fireplace. we had no sooner reached this house, very weary and so cold that we could scarcely move, than it was discovered that the courier had omitted to get the key from nicolosi, and there seemed a prospect of spending the hours till dawn in the open air. fortunately we had with us a chisel and a geological hammer, and by the aid of these we forced open the shutter serving as a window, and crept into the house; ten minutes later a large wood fire was blazing up the chimney, our eatables were unpacked, some hot coffee was made, and we were supremely comfortable. [illustration: the casa inglesi and cone of etna] at a.m. we left the casa inglesi for the summit of the great crater, , feet above us, in order to be in time to witness the sunrise. our road lay for a short distance over the upper portion of the piano del lago, and the walking was difficult. the brighter stars had disappeared, and it was much darker than it had been some hours before. the guide led the way with a lantern. the ascent of the cone was a very stiff piece of work; it consists of loose ashes and blocks of lava, and slopes at an angle of " ° or more" according to one writer, and of ° according to another; probably the slope varies on different sides of the cone: we do not think that the slope much exceeds ° anywhere on the side of the cone which we ascended. fortunately there was no strong wind, and we did not suffer from the sickness of which travellers constantly complain in the rarefied air of the summit. we reached the highest point at . a.m., and found a temperature of ° f. when sir william hamilton ascended towards the end of june the temperature at the base of the mountain was ° f., and at the summit ° f. when brydone left catania on may th, , the temperature was ° f., bar. in. - / lines; at nicolosi at midday on the th it was ° f., bar. in. - / lines; at the spelonca del capriole ( , feet), ° f., bar. in. - / lines; at the foot of the crater, temp. ° f., bar. in. - / lines, and at the summit of the crater just before sunrise, temp. ° f., bar. in. lines. on reaching the summit we noticed that a quantity of steam and sulphurous acid gas issued from the ground under our feet, and in some places the cinders were so hot that it was necessary to choose a cool place to sit down upon. a thermometer inserted just beneath the soil from which steam issued registered ° f. for a short time we anxiously awaited the rising of the sun. nearly all the stars had faded away; the vault of heaven was a pale blue, becoming a darker and darker grey towards the west, where it appeared to be nearly black. just before sunrise the sky had the appearance of an enormous arched spectrum, extremely extended at the blue end. above the place where the sun would presently appear there was a brilliant red, shading off in the direction of the zenith to orange and yellow; this was succeeded by pale green, then a long stretch of pale blue, darker blue, dark grey, ending opposite the rising sun with black. this effect was quite distinct, it lasted some minutes, and was very remarkable. this was succeeded by the usual rayed appearance of the rising sun, and at ten minutes to o'clock the upper limb of the sun was seen above the mountains of calabria. examined by the spectroscope the fraunhofer lines were extremely distinct, particularly two lines near the red end of the spectrum. the top of the mountain was now illuminated, while all below was in comparative darkness, and a light mist floated over the lower regions. we were so fortunate as to witness a phenomenon which is not always visible, viz., the projection of the triangular shadow of the mountain across the island, a hundred miles away. the shadow appeared vertically suspended in space at or beyond palermo, and resting on a slightly misty atmosphere; it gradually sank until it reached the surface of the island, and as the sun rose it approached nearer and nearer to the base of the mountain. in a short time the flood of light destroyed the first effects of light and shadow. the mountains of calabria and the west coast of italy appeared very close, and stromboli and the lipari islands almost under our feet; the east coast of sicily could be traced until it ended at cape passaro and turned to the west, forming the southern boundary of the island, while to the west distant mountains appeared. no one would have the hardihood to attempt to describe the various impressions which rapidly float through the mind during the contemplation of sunrise from the summit of etna. brydone, who is by no means inclined to be rapturous or ecstatic in regard to the many wonderful sights he saw in the course of his tour, calls this "the most wonderful and most sublime sight in nature." "here," he adds, "description must ever fall short, for no imagination has dared to form an idea of so glorious and so magnificent a scene. neither is there on the surface of this globe any one point that unites so many awful and sublime objects. the immense elevation from the surface of the earth, drawn as it were to a single point, without any neighbouring mountains for the senses and imagination to rest upon, and recover from their astonishment in their way down to the world. this point or pinnacle, raised on the brink of a bottomless gulph, as old as the world, often discharging rivers of fire and throwing out burning rocks with a noise that shakes the whole island. add to this, the unbounded extent of the prospect, comprehending the greatest diversity and the most beautiful scenery in nature, with the rising sun advancing in the east to illuminate the scene." when the sun had risen we had time to examine the crater, a vast abyss nearly feet in depth, and with very precipitous sides. its dimensions vary, but it is now between two and three miles in circumference. sometimes it is nearly full of lava, at other times it appears to be bottomless. at the present time it is like an inverted cone; its sides are covered with incrustations of sulphur and ammonia salts, and jets of steam perpetually issue from crevices. near the summit we found a deposit, several inches in thickness, of a white substance, apparently lava decomposed by the hot issuing gases. hydrochloric acid is said to frequently issue from the crater; the gases that were most abundant appeared to be sulphurous acid and steam. the interior of the crater appeared to be very similar to that of the solfatara near puzzuoli. during the descent from the cone we collected various specimens of ash and cinder, some red, others black and very vesicular, others crystalline, some pale pink. the steep slope of the cone was well shown by the fact that, although the surface is either extremely rugged owing to the accumulation of masses of lava, or soft and yielding on account of the depth of cinders, a large mass of lava set rolling at the top rushes down with increasing velocity until it bounds off to the level plain below. [illustration: view of the val de bove] the great cone is formed by the accumulation of sand, scoriæ, and masses of rock ejected from the crater; it is oval in form, and has varied both in shape and size in the course of centuries. when we saw it, it was not full of smoke or steam; but it was possible to see to the bottom of it, in spite of small jets of steam which issued from the sides. it presented the appearance of a profound funnel-shaped abyss; the sides of which were covered with an efflorescence of a red or yellow, and sometimes nearly white, colour. the crater presented the same appearance when it was seen by captain smyth in , but he was so fortunate as to witness it in a less quiescent state. "while making these observations," he writes, "on a sudden the ground trembled under our feet, a harsh rumbling with sonorous thunder was heard, and volumes of heavy smoke rolled over the side of the crater, while a lighter one ascended vertically, with the electric fluid escaping from it in frequent flashes in every direction.... during some time the ground shook so violently that we apprehended the whole cone would tumble into the burning gulf (as it actually had done several times before) and destroy us in the horrible consequences; however, in less than a couple of hours all was again clear above and quiet within." when mr. gladstone ascended in , the volcano was in a slight state of eruption: "the great features of this action," he writes, "are the sharp and loud claps, which perceptibly shook from time to time the ground of the mountain under our feet; the sheet of flame which leapt up with a sudden momentary blast, and soon disappeared in smoke; then the shower of red-hot stones and lava. at this time, as we found on our way down, lava masses of or pound weight were being thrown a distance of probably a mile and a half; smaller ones we found even more remote. these showers were most copious, and often came in the most rapid succession. even while we were ascending the exterior of the cone, we saw them alighting on its slope, and sometimes bounding down with immense rapidity within, perhaps, some thirty or forty yards of our rickety footing on the mountain side. they dispersed like the sparks of a rocket; they lay beneath the moon, over the mountain, thicker than ever the stars in heaven; the larger ones ascended as it were with deliberation, and descended, first with speed and then with fury. now they passed even over our heads, and we could pick up some newly fallen, and almost intolerably hot. lastly, there was the black grey column, which seemed smoke, and was really ash, and which was shot from time to time out of the very bowels of the crater, far above its edge, in regular unbroken form." at the casa inglesi we remounted the mules, and made a slight detour to the east in order to look down into the val del bove, which is here seen as a gigantic valley, bounded on the north by the precipitous cliffs of the serra delle concazze, and on the south by the serra del solfizio. it is believed by lyell and others that in the balzo di trifoglietto, at which point the precipices are most profound and abrupt, there was a second permanent crater of eruption. the torre del filosofo, a ruined tower, traditionally the observatory of empedocles, stands near the casa inglesi. not far from this a great deposit of ice was found in . it was preserved from melting by a layer of ashes and sand, which had covered it, soon after its first existence, as a glacier: a stream of lava subsequently flowed over the ashes, and completely protected the ice; the non-conducting power of the ashes prevented the lava from melting the ice. the snow which falls on the mountain is stowed away in caves, and used by the sicilians during summer. a ship load is also sent to malta, and the archbishop of catania derives a good deal of his income from the sale of etna snow. during our descent from the mountain we were much struck by the apparent nearness of the minor cones beneath us, and of the villages at the base of the mountain. they seemed to be painted on a vertical wall in front of us, and although from ten to fifteen miles distant they appeared to be almost within a stone's throw. this curious effect, which has often been observed before, is due to refraction. at the summit of etna we have left one-third of the atmosphere beneath us, and the air is now pressing upon the surface of the earth with a weight of ten pounds on the square inch, instead of the usual fifteen pounds experienced at the level of the sea. in looking towards the base of the mountain we are consequently looking from a rarer to a denser medium; and it is a law of optics, that when light passes from a denser to a rarer medium it is refracted away from the perpendicular, and thus the object, from which it emanates, appears raised, and nearer to us than it really is. the objects around etna appear near to us and raised vertically from the horizon for the same reason that a stick plunged in water appears bent. we reached nicolosi again about noon, having left it eighteen hours before. the ascent of the mountain, although it does not involve much hard walking, is somewhat trying on account of the extremes of temperature which have to be endured. in the course of the morning of our descent we had experienced a difference equal to more than ° f. as to the ascent, you are moving upwards nearly all night; you have six hours of riding on a mule, some of it in a bitterly cold atmosphere; you get very much heated by the final steep climb of feet, and you find at the summit a piercing wind; of course there is no shelter, and you sit down to wait for sunrise on cinders which are gently giving off steam and sulphurous acid; the former condenses to water as soon as it meets the cold air, and you find your great coat, or the rug on which you have sat down, speedily saturated with moisture. chapter iv. towns situated on the mountain. paterno.--ste. maria di licodia.--the site of the ancient town of aetna.--biancavilla.--aderno.--sicilian inns.--adranum.--bronte.-- randazzo.--mascali.--giarre.--aci reale.--its position.--the scogli de'ciclopi.--catania, its early history, and present condition. we have before alluded to the fact that etna is far more thickly populated than any other part of sicily or italy; in fact, more so than almost any equal area in the world, of course excepting large cities and their neighbourhood. this is due to the wonderful fertility of the soil, the salubrity of the climate, and, on the eastern base, to the proximity of a sea-coast indented with excellent harbours. the habitable zone of etna is restricted to the _regione coltivata_, nevertheless some of the towns on the north and west have a considerable elevation; thus bronte is , feet above the sea, and randazzo , . all the principal towns are situated on the base road of the mountain, which was indeed constructed in order to connect them. out of the sixty-four towns and villages on the mountain, the following are the most important: catania, aci reale, paterno, aderno, bronte, randazzo, aci s. antonio, biancavilla, calatabiano, giarre, francavilla, linguagrossa, licodia, mascali, misterbianco, nicolosi, pedara, piedemonte, trecastagne, and tremestieri. on our return from the summit, we rested for awhile at nicolosi, and in the cool of the evening started to make a _giro_ of the mountain by way of the base road. descending by the nicolosi road as far as mascalucia, we branched off to the west, and made for paterno, passing near the town of belpasso, which was destroyed by the earthquake of , and subsequently erected on a new site. it still contains more than , inhabitants, although the district is extremely unhealthy. paterno, the second largest town on the flanks of etna after catania and aci reale, stands in the very heart of the regione coltivata, and possesses more than , inhabitants. according to cluverius, it is the site of the city of hybla major (~hybla megalê~), a sikelian city which was unsuccessfully attacked by the athenians soon after they first landed in sicily. during the second punic war, the inhabitants went over to the carthagenians, but the city was speedily recovered by the romans. pliny, cicero, and pausanias allude to it, but its later history has not come down to us. an altar was lately found in paterno dedicated to _veneri victrici hyblensi_. several towns in sicily were called hybla, probably--according to pausanias--in honour of a local deity. paterno was founded by roger i. in : it was once a feudal city of some importance, and possessed a cathedral and castle, and several large monasteries. although much fallen to decay, it still possesses a good deal of vitality, and the population is on the increase. on leaving paterno the road turns to the north-west, and passes through the village of ste. maria di licodia. here originally stood the sikelian city of inessa (~inêssa~), which, after the death of hiero i., was peopled by colonists from katana (then called ~aitnê~). the new occupants of the city changed its name from inessa to aetna, which it retained. the town later fell into the hands of the syracusans, and in b.c. the athenians in vain attempted to take it. during the athenian expedition both aetna and hybla were allies of syracuse. in b.c. aetna was taken by dionysius, who placed in it a body of campanian mercenaries. sixty-four years later (b.c. ) the town was taken by timoleon. for many succeeding years we find no further mention of it. cicero speaks of it in his time as an important place, and the centre of a very fertile district; it is also mentioned by pliny and ptolemy, and strabo says that it was usually the starting point for those who ascended the mountain. of its later history we know absolutely nothing. six miles to the north-west of st. mariah di licodia, the road passes through biancavilla--a town of , inhabitants, and the centre of a cotton district. the road continues in the same direction until the town of aderno is reached; and here we arrived late in the evening, and gained our first experience of a sicilian inn in an out-of-the-way town. after many enquiries we were directed to the only inn which the place could boast, kept by a doctor. no one appeared at or near the entrance, of course there was no bell or knocker, and we made our way up a dark stone staircase till we arrived at a dimly-lighted passage. a horrible old sicilian woman now appeared, and showed us with great incivility the only room in the house, which its inmates were willing to place at our disposal. it was a fairly large room, with a stone floor which apparently had not been swept for weeks, and walls that had once been whitewashed; the furniture consisted of three beds placed on tressels, a plain deal table, and some primitive chairs. as to food they had neither bread, meat, wine, eggs, macaroni, fruit, or butter in the house; neither did they offer to procure anything. even when some eggs had been obtained, and (after an hour's delay) cooked, there was not a single teaspoon to eat them with. the people of the town appear to subsist chiefly on beans and a kind of dried fish. if our courier had not been a very handy fellow and a tolerable cook, we should have been obliged more than once to go to bed supperless. as it was, the best he could do on this occasion was to get some bread, eggs, and wine, and--best of all--some snow, for the heat was intolerable. in a town of the same size-- , inhabitants--in england, we should have at least two really comfortable inns ready at any moment to receive and entertain the weary traveller. [illustration: view of etna from bronte] aderno stands on the site, and has preserved the name, of the ancient sikelian city of adranum (~adranon~). according to diodorus there existed here, from very early times, the temple of a local deity named adranus. the city was founded by the elder dionysius in b.c.; it owed its importance to the renown of its temple, which was guarded by a thousand dogs. in b.c. the city fell into the hands of timoleon, and it was taken by the romans at the commencement of the first punic war. after this we cease to hear of it. the modern town was founded by roger i. in the th century. the fine norman tower--now used as a prison--and the monastery, were both built by king roger. after leaving aderno the base-road ascends, turns nearly due north, and leads us past a number of lava streams, notably those of , , and . a good view of monte minardo, and the minor cones in its more immediate neighbourhood, is obtained on the left, while on the right we see the valley of the simeto, and centorbi high upon the hills. nearly due west of the great crater is the town of bronte, which is , feet above the sea, and has a population of more than , . it is a very primitive place, and several centuries behind the age; it reminded us forcibly, in one or two particulars, of pompeii: the streets are narrow and tortuous, and the roadway very uneven. awnings are sometimes hung across the street from side to side to provide shade. the shops are exactly like those at pompeii; and in the main street we noticed an open-air kitchen, to which the would-be diner repairs, purchases a plateful of food, and eats it standing in the public way. the inn was even worse than that of aderno, and apparently had never before received guests. we were offered one miserable room, without a lock to the door, and unprovided with either table or chair. of course the bare idea of offering to procure, or furnish, or cook, any kind of food was too monstrous to be entertained for a moment. with difficulty the courier obtained some eggs, macaroni, and fruit, on which we dined in a small barn attached to a wine-shop. at bronte we are only nine miles from the crater, on the steepest side of the mountain, and near the tertiary sandstone which underlies this portion of the mountain. a short distance outside the town we saw great beds of the lava of , piled up fantastically in all sorts of forms, and excessively rugged and uneven. it is quite bare of vegetation, and does not appear to have even commenced to be decomposed. bronte gave its name to lord nelson, who was created duke of bronte by ferdinand iv.:--an appropriate name for a great warrior ([greek: brontê], thunder). the nelson estates are scattered around the town. on leaving bronte the road conducted us past several high hills of sandstone and quartzite near monte rivoglia; then we passed near maletto, and, leaving the malarious lake gurrita on our left, we soon after arrived at randazzo. near maletto the road reaches it highest point-- , feet. the town of randazzo was founded by the lombards in the th century; during the middle ages it appears to have been a prosperous, populous, place; at present it possesses more than , inhabitants. the emperor frederick ii. created his son duke of randazzo, and added to the name of the town, _etnea_. it contains several very interesting architectural remains; a church of the th century, a mediæval palace--the palazzo finochiaro,--and a ducal palace now used as a prison. the houses are for the most part built of lava, and some of the shops have massive lava counters extending half across their open front, while the door occupies the remainder, as at pompeii. the view from randazzo is very fine in every direction; the crater of etna appears near, and monte spagnuolo--many hours distant--just outside the town. the town is , feet above the sea, just above the valley of the alcantara--of which it commands a fine view, and also of the limestone hills on the other side. we were obliged to pass the night in the town, in an inn scarcely superior to that of aderno, but distinctly better than the miserable albergo collegio at bronte. at least the people were civil, and did their best. the one room of the inn had a bed in each corner, and a deal table in the middle. three of the beds were occupied by engineers who were surveying in connection with a new line of railway; the fourth was made over to the courier. i slept in a small kind of ante-room on a bed chiefly composed of deal boards placed on tressels. here again the courier was invaluable, in fact it would be simply impossible to make the circuit of etna without a courier. he procured some eggs, macaroni, fruit, snow, tomatoes, and even meat, and cooked everything well, without a trace of garlic. he also took care that the linen was clean, and the general arrangements as comfortable as they could be under the circumstances. let us also admit that neither at aderno, bronte, nor randazzo were we troubled with musquitoes or any worse species of insect. these, we were assured, would appear in full force in the following month (september). our only inconvenience of this nature arose from swarms of flies. the inns of these out-of-the-way towns probably receive scarcely a dozen travellers in the year, and these are sicilians, who are not used to better accommodation. evidently a _forestiare_ is quite a novelty: the people of these small towns used to look at us with great curiosity, and crowded round the carriage when we started. at bronte we had a good example of this curiosity: owing to the hardness of the lava of the head had come off the handle of our hammer, and we went into a carpenter's shop to have it put on again. presently we noticed that eleven people, including a priest, were looking on, apparently with intense and absorbing interest. from randazzo the base-road descends, until at giarre it is near the sea-level. this road is one of the most beautiful in sicily; it is part of the old military route from messina to palermo, and it was traversed by himilco in b.c.; by timoleon in b.c.; and by charles v. in . after leaving randazzo the valley of the alcantara becomes visible, while beyond it rise the lofty mountains of the nebrodes. the road passes near monte dolce, and soon reaches linguaglossa, a small town from whence the craters of may be reached in about four hours. the rapidly descending road passes through piedemonte and mascali, in the heart of an extraordinarily fertile region. mascali, a village of inhabitants, was considered by cluverius to be the site of the greek town of callipolis, founded by a colony from naxos as early as the fifth century, b.c. a full view of the coast line is obtained from the capo di taormina on the north, to a point below riposto on the south. we descended through plantations of nuts, and groves of oranges and lemons, to gentle slopes covered with vineyards. from the town of giarre, ( , inhabitants), we get a view of the val del bove, which, however, is almost always obscured by thin white clouds, while the summit of the mountain is clear. we noticed, indeed, every day that the summit, which had been absolutely clear all the day and night, became covered with clouds shortly before sunset, while about an hour later the clouds cleared off, and the mountain was sharply defined against the sky during the starlit night. some of the effects of sunset behind clouds resting on the summit, while all the rest of the sky was bright blue, were exceedingly beautiful, and were quite untranslatable into any known language, save that of painting, and of music. perhaps turner could have done justice to them. after leaving giarre we passed through a good deal of highly cultivated land belonging to baron pennisi, the largest landholder and richest man in sicily. he makes good use of his wealth, and seems to be very popular among all classes. he possesses three palaces in aci reale, and has done a great deal to beautify the town. archæologists will remember him as the possessor of the finest collection of sicilian coins in the world. many of these have been found on his own estates, but he never scruples to give large sums of money for any coin which he covets. aci reale, one of the prettiest towns in europe, is situated in the midst of a very fertile region feet above the sea. to the east it faces the ionian sea, while on the west towers etna. the town is full of wealthy inhabitants, and the houses are large, lofty, and well built. it contains , inhabitants, and possesses celebrated sulphur baths, and one of the best hotels in sicily. the wealth of this small town is well shown by the following fact: since its foundation in the tenth century, till within a year or two of the present time, the town had been under the jurisdiction of the archbishop of catania. it happened, however, a few years ago, on the occasion of a religious procession in catania, that the people of aci considered that their patron saint, s. venera, was slighted. in fact the image of s. agata, the patron saint of the catanese--whose veil has so often averted the lava-streams from the city--was put in all the prominent parts of the procession, while the image of s. venera was comparatively neglected. the people of aci at once returned home, and sent a petition to the pope, praying that they might have a bishop of their own directly subject to the holy see, in order that they might no longer be subjected to such slights. the vatican having duly considered the question consented to raise aci to the dignity of a bishopric, and to pay the bishop a yearly stipend of , lire, (about £ , but equal to £ in sicily), on condition that , lire were paid at once into the coffers of the vatican. this was promptly done, and now monsignore gerlando genuardi, bishop of aci reale, may snap his fingers in the face of monsignore giuseppe benedetto dusmet, a benedictine of the congregation of monte cassino, and archbishop of catania. [illustration: island of columnar basalt off trezza] six villages in the neighbourhood of aci reale bear the name of aci: aci castello, aci sant' antonio, and so on, but aci reale claims to stand upon the very site rendered memorable by the story of acis and galatea. the river acis (now called _acque grande_) rises from a bed of lava, and falls into the sea a mile from its source. aci reale stands on seven different beds of superposed lava, having layers of earth resulting from decomposed lava between. the canon recupero calculated from observation, that a lava requires at least years to form even a scanty layer of earth, consequently he inferred that the lowest of the lava streams upon which aci rests must have been formed , years ago. these views he stated to brydone a hundred years ago; the latter says, "recupero tells me he is exceedingly embarrassed by these discoveries in writing the history of the mountain. that moses hangs like a dead weight upon him, and blunts all his zeal for enquiry; for that really he has not the conscience to make his mountain so young as that prophet makes the world. what do you think of these sentiments from a roman catholic divine? the bishop, who is strenuously orthodox--for it is an excellent see--has already warned him to be upon his guard, and not to pretend to be a better natural historian than moses; not to presume to urge anything that may, in the smallest degree, be deemed contradictory to his sacred authority." the canon recupero lost his church preferment on the publication of brydone's book, and the whole body of clergy of girgenti received a reprimand on account of a capital story which brydone told of a dinner at which the bishop presided, during which several of the reverend canons suffered severely from the effects of english punch, which brydone had brewed for them. we quite agree with admiral smyth when he says, "it is a pity that mr. brydone laboured under such a cacoethes, as to sacrifice a friend for the sake of a good story." of course we now know that recupero's estimate of the age of etna was far within the true limits, but we derive this information from other sources. no true estimate can be obtained from the observation of the decomposition of lavas, for it has been often observed that two lavas will decompose at very different rates. a little to the north of the village of la scaletta, at the base of the rocks upon which aci reale stands, there are two small caverns in the abrupt face of the basalt, which can only be approached in a boat. they consist of columnar basalt bent very curiously, and capped by amorphous basalt. a drive of a few miles to the south of aci reale brings us to trezza, a small village built of lava. a short distance from the shore are the celebrated _scogli di ciclopi_, or rocks of the cyclops, said to be those which polyphemus hurled at ulysses after his escape from the cave. the rocks, seven in number, form small islets, the largest of which, the isola d'aci, is about feet in circumference, and feet high. it consists of crudely columnar basalt capped by a kind of marl. near the top of the island there is a cave called the "grotto of polyphemus," also a cistern of water. to the south of this island a very picturesque rock rises from the sea. it is feet in circumference and about feet in height, and consists of columnar basalt in four and eight-sided prisms, but not very regular; a hard calcareous substance is found in their interstices. fine crystals of analcime are sometimes met with in the basalts of the cyclops islands. lyell considers these basalts "the most ancient monuments of volcanic action within the region of etna." a few miles south of the isole di ciclopi are the bay and city of catania. we started from the latter when we commenced our ascent of etna, and now on returning to it, we completed the circuit of the mountain by its base-road of miles. katana (~katanê~) is believed to have been founded about b.c. by a greek colony of naxos, which had originally come from chalcis. the city maintained its independence till the time of hieron, who expelled the original inhabitants in b.c., and peopled the city with syracusans and inhabitants of the peloponnesus to the number of , . at the same time the name of the city was changed to aetna ([greek: aitnê]). in b.c., however, the old inhabitants retook their city, and drove out the newly-settled strangers, who betook themselves to inessa, occupied it, and changed its name to _aetna_. at a later period the katanians sided with the athenians against the syracusans. but in b.c. dionysius of syracuse took and plundered the city, sold the inhabitants as slaves, and established in it a body of campanian mercenaries. the latter quitted it and retired to aetna in b.c., when the city was taken by the carthaginians after a battle off the rocks of the cyclops. katana submitted to the romans in b.c., during the first punic war, and it soon became a very populous city. cicero mentions it as a wealthy city and important seaport. during the middle ages it underwent many changes both at the hands of nature and of man; it belonged in succession to the goths, saracens, and normans; and in was destroyed by an earthquake, during which , of its inhabitants perished. again in , and , it was almost destroyed by earthquakes. the present town is comparatively new, many of its more ancient remains are covered with lava, among them the remains of a fine greco-roman theatre, in which it is probable that alcibiades addressed the catanians in b.c. there are also remains of a roman amphitheatre, bath, and tombs. of more modern structures, the cathedral is the first to claim our notice. it was commenced by roger i. in , but in less than a century was almost entirely destroyed by an earthquake. at one corner of the building you descend through a narrow passage cut in the lava, to a crypt in which some ancient roman arches are shown, partly filled up with lava. here also is seen a small stream of very clear water flowing through the lava. the cathedral contains several interesting tombs, and in the chapel of s. agata, her body is preserved in a silver sarcophagus, which during certain fetes is carried through the town in procession, attended by all the authorities. s. agata was martyred by the prætor quintianus in the reign of decius, and is the patron saint of the city. whenever catania has been in trouble from the approach of lava streams, or from earthquakes, the veil of s. agata has been used as a charm to avert the evil. the university of catania is the most celebrated in sicily. it was founded in by alfonso of arragon, and has produced several men of eminence. the city also possesses one of the finest monasteries in the world, now converted into schools and barracks. formerly the monastery of s. nicola was occupied by monks, all members of noble families; it is sufficiently large to hold . chapter v. eruptions of the mountain. their frequency within the historical period.-- b.c.-- b.c.-- b.c.-- b.c.-- b.c.-- b.c.-- b.c.-- b.c.-- b.c. -- b.c.-- b.c.-- b.c.-- a.d.-- .-- .-- .-- .-- . -- .-- .-- .-- .-- .-- .-- .-- .-- .-- close of the fifteenth century.-- .-- -- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- . -- .-- .-- .-- .-- .-- .-- .-- .-- .-- .--flood of .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- .-- . -- .-- .-- .-- .-- .-- .-- .-- .-- .-- general character of the eruptions. a list of all the eruptions of etna from the earliest times has been given by several writers, notably by ferrara in his _descrizione dell' etna_, and by gemellaro. the latter places the first eruption in b.c. in the time of the sicani; the second in b.c.; and of the third he says, "in b.c. there was an eruption, and hercules in consequence fled from the island." of course these dates are worthless, and the statements are no doubt based upon the assertion of diodorus, that before the trojan war the sicani were driven from the east side of sicily by the eruptions of the volcano. . the first eruption appears to have occurred in the time of pythagoras; we have no details as to its nature. . the second eruption occurred in b.c. it is mentioned by thucydides, and it must be the eruption to which pindar and Æschylus allude. the former visited the tomb of hiero i. of syracuse in b.c., and the latter was in sicily in b.c. on the occasion of this eruption, two heroic youths named anapias and amphinomus, performed a deed to which seneca and other writers allude with enthusiasm. while the lava was rapidly overwhelming the city of katana, they placed their aged parents on their shoulders, and, at the risk of their lives, bore them through the flaming streets, and succeeded in placing them in safety. it was said that the fiery stream of lava parted to make way for them. statues were raised to the honour of the _pii fratres_, and their burial place was long known as the _campus piorum_. even a temple was erected to commemorate the deed. lucilius junior devotes the concluding lines of his poem on etna to the glory of the brothers: "the flames blushed to touch the filial youths, and wherever they plant their footsteps, they retire. that day is a day of fortune; harmless that land. on their right hand fierce dangers prevail; on their left are burning fires. athwart the flames they pass in triumph, his brother and he, each safe beneath his filial burden. there the devouring fire flees backward, and checks itself round the twin pair. at length they issue forth unharmed, and bear with them their deities in safety. songs of poets honour and admire them; them has pluto placed apart beneath a glorious name, nor can the mean fates reach the holy youths, but have truly granted them the homes and dominion of the blessed."[ ] [ ] translated by l. e. upcott, m.a. . the third eruption occurred in the year b.c. it is mentioned by thucydides as having commenced in the sixth year of the peloponnesian war. it destroyed a portion of the territory of the inhabitants of katana. . an important eruption occurred in the year b.c. it broke out from monte di mojo, the most northerly of the minor cones of etna, and following the course of the river acesines, (now the alcantara) entered the sea at the site of the ancient greek colony of naxos. himilco the carthaginian general, was at this time on his way from messana to syracuse, and he was compelled to march his troops round the west side of the mountain in order to avoid the stream of lava. . we hear of no further eruption for years, when in the year b.c., in the consulship of c. lælius sapiens and q. servilius cæpio, there was an outburst from the volcano which destroyed people. . six years later an eruption occurred according to orosius and julius obsequens, in the consulship of sergius fulvius flaccus, and quintus calpurnius piso. we have no details concerning its nature or extent. . the same authorities state that in the year b.c. in the consulship of l. oemilius lepidus, and l. aurelius orestes, sicily suffered from a very severe earthquake, and a deluge of fiery matter poured from etna, overwhelming large tracts of country, and rendering the waters of the adjacent ionian sea positively hot. it is said that the sea near the island of lipari boiled, and that the inhabitants ate so large a number of the fishes which were cast, already cooked, upon their shores, that a distemper appeared which destroyed a large number of people. . four years later katana was nearly destroyed by a new eruption. the roofs of many of the houses were broken in by the weight of hot ashes which fell upon them; but the lava stream turned aside near the city and flowed into the sea. the lava is believed to have issued from a small crater near gravina, about - / miles from katana. the city was so much injured by this eruption that the romans granted the inhabitants an immunity from all taxes for a space of ten years. . an eruption, of which we have no details, occurred during the civil war between cæsar and pompey. . livy speaks of an eruption and earthquake which took place shortly before the death of cæsar, which it was believed to portend. . in b.c., during the civil war between octavianus and sextus pompeius, a violent eruption occurred on the east side of the mountain, accompanied by fearful noises and outbursts of flame. . six years afterwards an eruption of a less violent character took place. . the next eruption of which we hear is that mentioned by suetonius in his life of caligula. the emperor happened to be at messina at the time, and he fled from the town through fear of the eruption. this was in a.d. . an eruption is said to have occurred in , in the second year after the capture of jerusalem by titus. . etna was now quiescent for nearly two centuries, but in the year , in the reign of the emperor decius, a violent eruption lasting nine days occurred. the lava flowed in the direction of catania, and the inhabitants for the first time tested the efficacy of the veil of s. agatha, which afterwards stood them in such good stead on more than one occasion. the saint had been martyred the year before, and when the frightened inhabitants saw the stream of lava approaching the city, they rushed to the tomb, and removed the veil which covered her body. this was carried to the edge of the descending torrent of lava, and is asserted to have at once arrested its progress. . according to carrera and photius an eruption occurred in the year . . we now find no record of any volcanic action for nearly four hundred years. geoffrey of viterbo states that an eruption occurred in , when charlemagne was in messina. . after another long interval of more than three centuries and a half, the mountain again entered into eruption. in february, , occurred one of the most disastrous eruptions on record. a violent earthquake, which was felt as far as reggio, occurred about dawn, and in a few minutes catania was a heap of ruins. it is estimated that , persons were buried beneath the ruins. it was the vigil of the feast of s. agatha, and the cathedral of catania was crowded with people, who were all buried beneath the ruins, together with the bishop and forty-four benedictine monks. the side of the cone of the great crater towards taormina fell into the crater. at messina the sea retired to some distance from the shore, and then suddenly returned, overwhelming a portion of the city, and sweeping away a number of persons who had fled to the shore for safety. the clear and pure fountain of arethusa at syracuse became muddy and brackish; while the fountain of ajo, near the village of saraceni, ceased to flow for two hours, and then emitted water of the colour of blood. ludovico aurelio states that the vines, corn, and trees were burnt up over large districts. . according to nicolo speziale, there was a great eruption from the eastern side of the mountain in . . a stream of lava is said to have burst from the eastern side of the mountain in , when charles of anjou was on his death-bed, and to have flowed fifteen miles. . in the year niccolo speziale was in catania, and witnessed the eruption of which he has left us an account. on the evening of june th, about the hour of vespers, etna was strongly convulsed, terrible noises were emitted, and flames issued from the south side of the mountain. a new crater--monte lepre--opened in the val del bove above the rock of musarra, and emitted large quantities of dense black smoke. soon afterwards a torrent of lava poured from the crater, and red-hot masses of rock were projected into the air. these effects continued till the th of july, when a second crater opened ten miles to the s.e. of montelepre, and near the church of s. giovanni paparometto. soon after four other craters opened around it, and emitted smoke and lava. the sun was obscured from morning till evening by the smoke and ashes, and the adjacent fields were burnt up by the hot sand and ashes. multitudes of birds and animals perished, and many persons are said to have died from terror. the lava streams were divided into three portions, two of which flowed towards aci, and the third towards catania. the ashes were carried as far as malta, a distance of miles. . four years afterwards an eruption is recorded by silvaggio. . a manuscript preserved in the archives of the cathedral of catania mentions an eruption which occurred on the th of august, , which caused the destruction of numerous olive groves near the city. . an eruption which lasted for twelve days commenced on the th of november, ; it originated in the great crater, but several mouths subsequently opened near the base of the mountain. large quantities of red-hot ashes were emitted, some of which fell in calabria. the villages of pedara and tre castagne suffered severely from this eruption. . a violent earthquake in caused the upper cone of the mountain to fall into the crater. a torrent of lava also issued from the mountain, and moved for a space of twenty days towards catania, but it did not reach the city. . two years later lava issued from the val del bove near the rock of musarra; the crater then formed was perhaps the present monte finocchio. . a short eruption, of which we have no details, occurred in : after which etna was quiescent for years. . bembo and fazzello mention an eruption which occurred towards the close of the th century, during which a current of lava flowed from the great crater, and destroyed a portion of catania. in filoteo, of whom we have before spoken as one of the earliest historians of etna, descended into the crater, which possessed its present funnel-like form. he found at the bottom a hole, not larger than a man's head, from which issued a thin moist sulphurous vapour. . in march, , a quantity of lava issued from the great crater, and several new apertures opened near the summit of the mountain and emitted lava. it divided into several streams, flowing in different directions, one towards randazzo, a second towards aderno, and a third towards bronte. the lava swept everything before it; at the same time quantities of smoke and ashes were ejected, the mountain was convulsed, and fearful noises were heard. three new craters were formed on the south and west sides of the mountain, and on the th of march twelve new craters, or _bocche_, opened between monte manfre and monte vituri. a physician of lentini, named negro di piazza, having approached too near to the scene of the eruption, was destroyed by a volley of red-hot stones. several rifts were formed in the sides of the mountain from which issued flames and hot cinders. . a year later, in may, , a fresh outburst occurred; a number of new mouths were opened on the south slope of the mountain near la fontanelle, and a quantity of lava was emitted, which flowed in the direction of catania, destroying a part of nicolosi, and s. antonio. in four days the lava had run fifteen miles. at the same time violent shocks of earthquake occurred all over sicily, the inhabitants thought that the last day had come, and many prepared for their end by receiving extreme unction. according to filoteo the noises were so violent that many persons were struck deaf. the sun was obscured by smoke and dust, ashes fell in sufficient quantities to destroy the olive plantations of messina, and were even carried miles out to sea. the great crater suddenly fell in, so as to become level with the piano del lago. the height of the mountain was thus diminished by feet. . three new craters opened in november, , on the north-east slope of the mountain. quantities of lava were emitted, which flowed towards linguaglossa and randazzo. . a slight eruption, of which we have no details, occurred in . . according to carrera, an eruption occurred in june, . the mountain was shaken with earthquakes, and great volumes of smoke and flame were emitted. . a stream of lava issued from the great crater four years later, and filled up the lake which had previously existed in the piano del lago. . in february, , lava was emitted from the great crater. it flowed towards aderno, and filled up the bed of the simeto, a little above the ponte di carcaci. a few months later a second stream destroyed a large portion of the forest del pino. . in several new craters were opened between randazzo and the great crater on the north side of the mountain. a quantity of lava issued from them, which united into one stream, and ran for ten miles, destroying a great deal of wooded country. . a slight eruption occurred in . . in february, , nicolosi was partially destroyed by a violent earthquake; and in the following december earthquakes became frequent on the mountain. a new crater opened above the cone called serrapizzuta, five miles from the great crater, and emitted a good deal of lava. a second crater afterwards opened about two miles to the east of the former. the eruption lasted off and on for four years: the ejected lava then covered a tract eighteen miles in length by two miles in width, the thickness sometimes attaining feet. in a severe earthquake occurred, which was mainly felt on the west side of the mountain. . in a new mouth opened on the north-north-east side of the mountain, five miles from the great crater. the lava flowed towards castiglione. . in february, , several new mouths opened on the west side of the mountain, and poured out vast volumes of lava which threatened to overwhelm bronte. in twenty-four hours the lava ran sixteen miles with a breadth of four miles. . we have a more detailed account of the eruption of than of any previous outburst. it was observed by many men of different nations; and we find accounts of it in our own _philosophical transactions_, in french, and of course in italian. perhaps the most accurate and complete description is that given by alfonso borelli, professor of mathematics in catania. the eruption was, in every respect, one of the most terrible on record. on the th of march the sun was obscured, and a whirlwind blew over the face of the mountain; at the same time earthquakes commenced, and continued to increase in violence for three days, when nicolosi was converted into a heap of ruins. on the morning of the th a fissure nearly twelve miles in length opened in the side of the mountain, and extended from the piano di s. leo to monte frumento, a mile from the summit. the fissure was only six feet wide, but it seemed to be of unknown depth, and a bright light proceeded from it. six mouths opened in a line with the principal fissure; they emitted vast columns of smoke, accompanied by loud bellowings which could be heard miles off. towards the close of the day, a crater opened about a mile below the others, and it ejected red hot stones to a considerable distance, and afterwards sand and ashes which covered the country for a distance of miles. the new crater soon vomited forth a torrent of lava which presented a front of two miles, it encircled monpilieri, and afterwards flowed towards belpasso, a town of inhabitants, which was speedily destroyed. seven mouths of fire opened around the new crater, and in three days united with it, forming one large crater feet in diameter. the torrent of lava all this time continued to descend, and it destroyed the town of mascalucia on the rd of march. on the same day the crater cast up great quantities of sand, ashes, and scoriæ, and formed above itself the great double-coned hill now called monti rossi from the red colour of the ashes of which it is mainly composed. on the th very violent earthquakes occurred, and the cone of the great central crater was shaken down into the crater for the fifth time since the first century a.d. the original current of lava had divided into three streams, one of which destroyed s. pietro, the second camporotondo, and the third the lands about mascalucia, and afterwards the village of misterbianco. fourteen villages were altogether destroyed, and the lava was on its way to catania. at albanelli, two miles from the city, it undermined a hill covered with cornfields, and carried it forward a considerable distance; a vineyard was also seen to be floating on its fiery surface. when the lava reached the walls of catania it accumulated without progression until it rose to the top of the wall, feet in height, and it then fell over in a fiery cascade, and overwhelmed a part of the city. another portion of the same stream threw down feet of the wall, and flowed into the city. on the rd of april the lava reached the sea, which it entered as a stream yards broad and feet deep. the stream had moved at the rate of thirteen miles in twenty days, but as it cooled it moved less quickly, and during the last twenty-three days of its course it only moved two miles. on reaching the sea the water of course began to boil violently, and clouds of steam arose, carrying with them particles of scoriæ. towards the end of april the stream on the west side of catania, which had appeared to be consolidated, again burst forth, and flowed into the garden of the benedictine monastery of s. niccola, and then branched off into the city. attempts were made to build walls to arrest its progress. an attempt of another kind was made by a gentleman of catania, named pappalardo, who took fifty men with him, having previously provided them with skins for protection from the intense heat, and with crowbars to effect an opening in the lava. they pierced the solid outer crust of solidified lava, and a rivulet of the molten interior immediately gushed out, and flowed in the direction of paterno; whereupon men of that town, alarmed for its safety, took up arms, and caused pappalardo and his men to desist. the lava did not altogether stop for four months; and two years after it had ceased to flow it was found to be red hot beneath the surface. even eight years after the eruption quantities of steam escaped from the lava after a shower of rain. the stones which were ejected from the crater during this eruption were often of considerable magnitude, and borelli calculated that the diameter of one which he saw was feet; it was thrown to a distance of a mile, and as it fell it penetrated the earth to a depth of feet. the volume of lava emitted during this eruption amounted to many millions of cubic feet: ferrara considers that the length of the stream was at least fifteen miles, while its average width was between two and three miles, so that it covered at least forty square miles of surface. in a somewhat rare tract,[ ] lord winchelsea, who was returning to england from constantinople, and who landed at catania, gives an account of what he saw of the eruption. he appears to have been frightened at the sight, and took good care to keep in a safe place; hence his letter, which is a short one, is mainly founded on hearsay. however, he says, "i could discern the river of fire to descend the mountain, of a terrible fiery or red colour, and stones of a paler red to swim thereon, and to be as big as an ordinary table.... of , persons which inhabited catania, did only remain; all their goods are carried away, the cannon of brass are removed out of the castle, some great bells taken down, the city gates walled up next the fire, and preparations made by all to abandon the city." the noble earl is less happy in his scientific ideas than in his general statement of the facts of which he was an eye-witness; we can only hope that he joined the recently-formed royal society on his return to england, and listened to robert hooke's discourse on fire. in describing the lava, lord winchelsea says, "the composition of this fire, stones, and cinders, are sulphur, nitre, quicksilver, sal-ammoniac, lead, iron, brass, and all other mettals!" two other accounts are appended to the above letter; in one of these we are told that as the lava approached catania, the various religious bodies carried their relics in procession, "followed by great multitudes of people, some of them mortifying themselves with whips, and other signs of penance, with great complaints and cries, expressing their dreadful expectation of the events of those prodigious fiery inundations." in the midst of all this, news was brought that a large band of robbers had taken advantage of the general distress, and were robbing right and left, and murdering the people: whereupon a troop of spanish horse was sent out to protect the city and country, three pair of gallows were set up, and such as were found robbing were executed without trial by martial law. [ ] "a true and exact relation of the late prodigious earthquake and eruption of mount Ætna or monte gibello; as it came in a letter written to his majesty from naples by the rt. honble. the earl of winchelsea late ambassadour at constantinople, who in his return from thence visiting catania in the island of sicily, was an eye-witness of that dreadful spectacle." published by authority. printed by t. newcomb in the savoy. . as the lava streams approached the city, the senate, accompanied by the bishop and all the clergy, secular and regular, went in procession out of the city to monte di s. sofia with all their relics, etc. there they erected an altar in view of the burning mountain, and celebrated mass, "and used the exorcismes accustomed upon such extraordinary occasions, all which time the mountain ceased not as before with excessive roaring to throw up its smoak and flames with extraordinary violence, and abundance of great stones, which were carried through the air." . for a few years after this terrible eruption etna was quiescent, but in a new mouth opened on the east side of the mountain, a little below the summit, and above the val del bove. lava issued from it, and rushed down the precipices of the val del bove as far as the rock of musarra. . six years later a torrent of lava burst from an opening in the great cone, and flowed into the val del bove for a distance of three miles. . in the following year lava was emitted from a mouth in the val del bove, and it descended for about ten miles, destroying everything in its course, until it reached a little valley near macchia. . early in january , clouds of black smoke were poured from the great crater, and loud noises resembling the discharge of artillery were heard. a violent earthquake succeeded, and catania was shaken to the ground, burying , of its inhabitants in the ruins. it is said that in all fifty towns were destroyed in sicily, together with from , to , inhabitants. lava was emitted from the crater, which was lowered by the eruption. . in the following year etna again entered into eruption, ejecting large quantities of ashes, some of which were carried as far as malta. . in march , three mouths opened in the contrada del trifoglietto, near the head of the val del bove. lava was emitted from them, which flowed into the valley of calanna. . towards the end of loud bellowings issued from the mountain; earthquakes occurred, and a torrent of lava issued from the crater, which flowed towards bronte, through the bosco di bronte. . a small lava stream issued from the crater in , and descended the western slope of the mountain, but without producing any damage. . in october , the usual noises which presage an eruption were heard, earthquakes followed, and a little later the crater emitted flames and red-hot stones. lava also issued from it, and the stream divided into three branches, one of which flowed towards bronte, a second towards linguaglossa, and a third towards mascali; but they did not get beyond the upper regions of the mountain. . in the mountain threw out great quantities of ashes, but no lava. . in a quantity of lava flowed from the great crater into the val del bove, and the height of the cone was considerably increased during the eruption. . early in the year , etna began to show signs of disturbance; a great column of black smoke issued from the crater, from which forked lightning was frequently emitted. loud detonations were heard, and two streams of lava issued from the crater. a new mouth opened near the rocca di musarra in the val del bove, four miles from the summit, and a quantity of lava was ejected from it. an extraordinary flood of water descended from the val del bove, carrying all before it, and strewing its path, with huge blocks. recupero estimated the volume of water as , , cubic feet, probably a greater amount than could be furnished by the melting of all the winter's snow on the mountain. it formed a channel two miles broad, and, in some places, thirty-four feet deep, and it flowed at the rate of a mile in a minute and a half during the first twelve miles of its course. lyell considers the flood was probably produced by the melting, not only of the winter's snow, but also of older layers of ice, which were suddenly melted by the permeation of hot steam and lava, and which had been previously preserved from melting by a deposit of sand and ashes, as in the case of the ancient glacier found near the summit of the mountain in . in november , a smart shock of earthquake caused the cone of the great crater to fall in, but no eruption occurred at the time. . great quantities of ashes, and some small streams of lava, were emitted from the crater in , a little later the cone, which had been again raised by the eruption, gave way, and the greater part of it fell into the crater. two parts of it however were left standing. . severe shocks of earthquakes were felt on the east side of the mountain in , and a new mouth opened in the bosco di bronte, ten miles from the town, between monte rosso and monte lepre. four other mouths were afterwards opened in a line; they threw up quantities of scoriæ and ashes, and afterwards lava. in the middle of june several mouths opened on the south side of the mountain, and a fissure feet long opened downwards in a southerly direction. the lava divided into two branches, the larger of which was ten miles long and feet wide, with a depth of feet. . several new mouths opened in the spring of , and ejected large volumes of ashes, also streams of lava, which flowed in the direction of nicolosi and pedara. the canon recupero, one of the historians of etna, witnessed this eruption, and narrowly escaped being destroyed. he had ascended a small hill feet high, of ancient volcanic matter, in order to witness the approach of the lava stream which was slowly advancing with a front of two miles and a half. suddenly two small streams detached themselves from the main stream, and ran rapidly towards the hill. recupero and his guide at once hastened to descend, and had barely escaped when they saw the hill surrounded by lava, and in a few minutes it was melted down and sank into the molten mass. . in the early part of , earthquakes were felt all over sicily, and on the th of may a fissure opened on the south-west side of the mountain, and extended from the base of the great crater for seven miles, terminating in a new mouth from which a stream of lava emanated. this encountered the cone of palmintelli in its course, and separated into two branches, each of which was feet wide. other mouths opened later in the year, and emitted large quantities of lava, which devastated the country of montemazzo. . in the volcano emitted a quantity of lava which flowed into the val del bove. clouds of grey ashes were also ejected. at the commencement of the great calabrian earthquake of , etna ejected large quantities of smoke, but it was otherwise quiescent. . in the middle of lava burst from the great crater, which also discharged quantities of sand, scoriæ, and red-hot ashes. large heated masses of rock were ejected to a great height, and subterranean bellowings were heard by the dwellers on the mountain. . five years afterwards a fresh outburst occurred, earthquakes were prevalent, and vast volumes of smoke bore to seaward, and seemed to bridge the sea between sicily and africa. a torrent of lava flowed towards aderno, and a second flowed into the val del bove as far as zoccolaro. a pit called _la cisterna_, feet in diameter, opened in the piano del lago, near the great cone, and ejected smoke and masses of old lava saturated with water. several mouths opened below the crater, and the country round about zaffarana was desolated. the abate ferrara, the author of the _descrizione dell' etna_, witnessed this eruption: "i shall never forget," he writes, "that this last mouth opened precisely on the spot where, the day before, i had made my meal with a shepherd. on my return next day he related how, after a stunning explosion, the rocks on which we had sat together were blown into the air, and a mouth opened, discharging a flood of fire, which, rushing down with the rapidity of water, hardly gave him time to make his escape." . in a slight eruption occurred, and the great crater threw out ashes and sand, but no lava. earthquakes were frequent. . in the following year lava was emitted, and severe earthquakes occurred. . the eruptions continued during . . in february loud explosions were heard by the dwellers on the mountain, and columns of fire issued from the crater, accompanied by forked lightning. this was succeeded by a discharge of hot ashes and scoriæ, which, falling on the snows accumulated near the summit of the mountain, produced devastating floods of water. . in november a new mouth opened near the rocca di musarra in the val del bove, which emitted a copious stream of lava. in a day and a half the lava had run twelve miles. . in the great crater was in a state of eruption, and a cone was thrown up within it to a height of , feet. . in the mountain again became active, and fire and smoke were emitted from the crater. . in march , no less than twenty-one mouths of fire opened in the direction of castiglione. they ejected volumes of smoke, large quantities of scoriæ and ashes, and afterwards lava, which, uniting into one torrent, flowed with a front of feet for miles. fissures were formed in the earth, and loud explosions constantly occurred within the great crater; a small cone was thrown up. . two years afterwards more than thirty mouths opened in a line running eastwards for five miles. they ejected jets of fire accompanied by much smoke. the eruptions soon diminished in the higher mouths, and became more and more violent in the lower mouths, until the eruption centred in the lowest one called s. simone, near the head of the val del bove. from this, great black clouds, having a lustre like that of black wool, issued, and afterwards quantities of lava, which formed a stream a mile wide, and eight miles long. it flowed nearly as far as the village of milo. frequent earthquakes accompanied this outburst, and they continued in various parts of the island for the following five years. . in five new mouths of fire opened near the scene of the eruption of ; three of these united into one large crater, and poured forth a quantity of lava into the val del bove. the lava flowed until it reached a nearly perpendicular precipice at the bend of the valley of calanna, over which it fell in a cascade, and, being hardened by its descent, it was forced against the sides of the tufaceous rock at the bottom, so as to produce an extraordinary amount of abrasion, accompanied by clouds of dust, worn off by the friction. mr. scrope observed that the lava flowed at the rate of about a yard an hour, nine months after its emission. . a slight eruption occurred in from the great crater, which threw out lava on its northern side. . in october of the following year a violent eruption occurred. a new crater was formed in the val del serbo, above bronte and three miles from the summit. seven mouths afterwards opened, three miles below the first. from one of these lava was emitted, which flowed to within a mile and a half of bronte. the stream was a mile and a half broad, and feet deep. . a slight eruption occurred in , when a small quantity of lava was poured from the great crater into the val del bove. . four years later the crater discharged ashes and scoriæ, and lava burst from the cone feet from the summit. it flowed into the val del bove, in a stream feet wide, and it came to a standstill ten miles from the summit. . near the end of the following year, fifteen mouths of fire opened near the crater of , at a height of feet above the sea. they began by discharging scoriæ and sand, and afterwards lava, which divided into three streams, the two outer ones soon came to a standstill, while the central stream continued to flow at the rapid rate of feet a minute, the descent being an angle of °. the heat at a distance of feet from the current was ° f. a new crater opened just above bronte, and discharged lava which threatened the town, but it fortunately encountered monte vittoria and was diverted into another course. while a number of the inhabitants of bronte were watching the progress of the lava, the front of the stream was suddenly blown out as by an explosion of gunpowder; in an instant red-hot masses were hurled in every direction; and a cloud of vapour enveloped everything. thirty-six persons were killed on the spot, and twenty survived but a few hours. the great crater showed signs of disturbance, by emitting dense volumes of smoke, and loud bellowings, also quantities of volcanic dust saturated with hydrochloric acid, which destroyed the vegetation wherever it fell. . a very violent eruption which lasted more than nine months, commenced on the st of august, . it was first witnessed by a party of six english tourists, who were ascending the mountain from nicolosi in order to see the sunrise from the summit. as they approached the casa inglesi the crater commenced to give forth ashes and flames of fire. in a narrow defile they were met by a violent hurricane, which overthrew both the mules and their riders, and urged them towards the precipices of the val del bove. they sheltered themselves beneath some masses of lava, when suddenly an earthquake shook the mountain, and their mules in terror fled away. they returned on foot towards daylight to nicolosi, fortunately without having sustained injury. in the course of the night many _bocche del fuoco_ opened in that part of the val del bove called the balzo di trifoglietto, and a great fissure opened at the base of the giannicola grande, and a crater was thrown up from which for seventeen days showers of sand and scoriæ were ejected. during the next day a quantity of lava flowed down the val del bove, branching off so that one stream advanced to the foot of monte finocchio, and the other to monte calanna. afterwards it flowed towards zaffarana, and devastated a large tract of woody region. four days later a second crater was formed near the first, from which lava was emitted together with sand and scoriæ, which caused cones to rise around the craters. the lava moved but slowly, and towards the end of august it came to a stand, only a quarter of a mile from zaffarana: on the second of september, gemellaro ascended monte finocchio in the val del bove in order to witness the outburst. he states that the hill was violently agitated, like a ship at sea. the surface of the val del bove appeared like a molten lake; scoriæ were thrown up from the craters to a great height, and loud explosions were heard at frequent intervals. the eruption continued to increase in violence. on october th two new mouths opened in the val del bove, emitting lava which flowed towards the valley of calanna, and fell over the salto della giumenta, a precipice nearly feet deep. the noise which it produced was like that of the clash of metallic masses. the eruption continued with abated violence during the early months of , and it did not finally cease till may . the entire mass of lava ejected is estimated to be equal to an area six miles long by two miles broad, with an average depth of about twelve feet. i am indebted to m. antonin moris of palermo for the following account of the eruption of : the eruption of commenced on the st of august. the earthquakes, the jets of flame from the great crater, and the subterranean rumblings which usually precede an eruption, did not herald the approach of this one. an english family, who were then making the ascent of the mountain, together with a poor shepherd of riposto, were the only witnesses of the first outburst. the latter was asleep in the midst of his flocks, and was awakened by violent shakings of the ground; he fled in haste, and some seconds afterwards the earth opened with a loud noise, vomiting a terrible column of fire, at the very spot which he had just abandoned. an enormous crevasse opened on the north side of trifoglietto in the direction of the great crater. on its summit near the opening called the piccolo teatro, several openings were produced at the very first, but they only emitted feeble currents of lava. all the force of the eruption was concentrated at the foot of the escarpment of the serra di giannicola, kilometres, ( - / miles) from the summit of etna. to the west of, and somewhat above the principal crater, a second one was formed, but its activity was of short duration. the liquid lava issued with such violence that in hours it had reached the base of monte calanna, a distance of kilometres, (nearly miles). after surrounding this hill, it divided into two currents, one of which ran towards zaffarana, and the other towards milo. at a distance they seemed to present a united front of kilometres, ( - / mile), which threatened to destroy all the villages below. the val del bove was already entirely overrun; isoletta dei zappinelli in the midst of the lavas of and was overwhelmed; the valley of calanna was buried under the fire with lava, when on the th of august the lava hurled itself into the narrow passage of the portella di calanna. a frightful cascade of lava was then seen to precipitate itself from a height of metres, with a harsh metallic noise, accompanied by loud cracking. zaffarana was on the eve of total ruin; the fire had taken the direction of the ravine which terminates there, when suddenly, in the beginning of september, the devastating stream stayed its march against the ill-fated district. on the contrary that which had taken the direction of milo, reinforced by a new current on the th of september, destroyed the hamlet of caselle del milo; and afterwards divided itself into two branches, which left the village of caselle in safety between them. the inhabitants of la macchia and giarre gave themselves up for lost; for it seemed that the lava would be obliged to follow the valley of santa maria della strada; happily, however, from the th of september onward, it ceased to advance perceptibly. the eruption did not totally subside till march ; but the lava-flows did no more than travel by the side, or on the top of the older, without extending beyond them. the crater of was called the centenario, from its having been formed at the time of the centenary of the fête of s. agatha. santiago, in the island of cuba, was destroyed by an earthquake on the very day of the eruption. during the whole period of the eruption, only one explosion proceeded from the great crater of etna. by it an enormous column of ashes and scoriæ was cast into the air. on the th of september white ashes were seen on the summit, which at a distance appeared like snow. when pressed together by the hand they took the consistence of clay, but they hardened in the fire, and could then be reduced to powder. they have been considered to be the _debris_ of felspathic rocks, disintegrated by the heat of the lava, and blown out by the expansive power of disengaged gas. the eruption of was one of the grandest of the recorded eruptions of etna. more than , , , cubic feet of red hot lava was spread over three square miles. this eruption was minutely described by carlo gemellaro, in a memoir entitled, "_breve ragguaglio della eruzione dell' etna del agosto, _." . in october , frequent shocks of earthquakes were felt by the dwellers on etna. in january clouds of smoke were emitted by the great crater, and roaring sounds were heard. on the night of the th a violent shock was felt on the north-east side of the mountain, and a mouth opened below monte frumento, from which lava was ejected. it flowed at a rate of about a mile a day, and ultimately divided into two streams. by march th the new mouths of fire had increased to seven in number, and they were all situated along a line stretching down from the summit. the three upper craters gave forth loud detonations three or four times a minute. professor orazio silvestri has devoted a quarto of pages to an account of _i fenomeni vulcanici presentati dall'etna nel - - - _. . in august the inhabitants of the towns situated on the north, west, and east sides of the mountain, were awakened by loud subterranean rumblings. soon afterwards a formidable column of black smoke issued from the crater, accompanied by sand, scoriæ, and ignited matter (_infuocata materia_). severe shocks of earthquake were felt, the centre of impulsion being apparently situated on the northern flank of the mountain, at a height of metres above the level of the sea. some small _bocche eruttive_ opened near the great crater, and ejected lava, but the quantity was comparatively small, and but little damage was done. an account of this eruption was given by silvestri in , in a small pamphlet entitled, _notizie sulla eruzione dell' etna del agosto, _. since the mountain has been in a quiescent state. the centre of disturbance was at an elevation of metres ( feet) above the sea, on the north side of the crater, and between the minor cones known as the _fratelli pii_ and _monte grigio_. a new crater, having an elliptical contour, and a diameter of about metres, was formed at this point. it is composed of a prehistoric grey labradorite, and of doleritic lava. downwards from the main crater, in the direction of monte di mojo, a long fissure extended for metres, and along the line of this fissure no less than _thirty-five_ minor cones opened, with craters of from thirty to three metres in diameter. the stream of lava ejected from the various _boccarelle_ was metres long, wide, and metres in thickness, and the bulk of volcanic material brought to the surface, including the principal cone and its thirty-five subordinates and their ejectamenta, was calculated to amount to , , cubic metres. the lava is of an augitic character, and magnetic; it possesses a specific gravity of · at ° c. it will be seen from the account of the foregoing eruptions that there is a great similarity in the character of the eruptions of etna. earthquakes presage the outburst; loud explosions follow, rifts and _bocche del fuoco_ open in the sides of the mountain; smoke, sand, ashes, and scoriæ are discharged, the action localises itself in one or more craters, cinders are thrown up, and accumulate around the crater and cone, ultimately lava rises, and frequently breaks down one side of the cone, where the resistance is least. then the eruption is at an end. smyth says, "the symptoms which precede an eruption are generally irregular clouds of smoke, ferilli, or volcanic lightnings, hollow intonations, and local earthquakes that often alarm the surrounding country as far as messina, and have given the whole province the name of val demone, as being the abode of infernal spirits. these agitations increase until the vast cauldron becomes surcharged with the fused minerals, when, if the convulsion is not sufficiently powerful to force them from the great crater (which, from its great altitude and the weight of the candent matter, requires an uncommon effort), they explode through that part of the side which offers the least resistance with a grand and terrific effect, throwing red-hot stones and flakes of fire to an incredible height, and spreading ignited cinders and ashes in every direction." after the eruption of ashes, lava frequently follows, sometimes rising to the top of the cone of cinders, at others breaching it on the least resisting side. when the lava has reached the base of the cone, it begins to flow down the mountain, and being then in a very fluid state, it moves with great velocity. as it cools the sides and surface begin to harden, its velocity decreases, and in the course of a few days it only moves a few yards in an hour. the internal portions, however, part slowly with their heat, and months after the eruption, clouds of steam arise from the black and externally cold lava beds after rain, which, having penetrated through the cracks, has found its way to the heated mass within. of the seventy-eight eruptions described above, it will be noticed that not more than nineteen have been of extreme violence, while the majority have been of a slight and comparatively harmless character. [illustration: geological map of etna] chapter vi. geology and mineralogy of the mountain. elie de beaumont's classification of rocks of etna.--hoffman's geological map.--lyell's researches.--the period of earliest eruption.--the val del bove.--two craters of eruption.--antiquity of etna.--the lavas of etna.--labradorite.--augite.--olivine.-- analcime.--titaniferous iron.--mr. rutley's examination of etna lavas under the microscope. the opinion of geologists is divided as to the manner in which a volcano is first formed. some hold that the volcanic forces have upraised the rocks from beneath, and at last finding vent have scattered the lighter portions of such rocks into the air, and have poured out lava through the rent masses, thus forming a _crater of elevation_. others maintain that the volcanic products are ejected from an aperture or fissure already existing in rocks previously formed, and that the accumulation of these products around the vent forms the mass of the volcano and the _crater of eruption_. lyell favours the latter view; von buch, dufrénoy, and elie de beaumont the former. according to m. elie de beaumont, etna is an irregular crater of elevation. the original deposits were nearly horizontal, and lavas were poured through fissures in these, and accumulated at first in layers; afterwards the whole mass was upheaved and a crater formed.[ ] the upheaving force does not appear to have acted at one point, but along a line traversing the val del bove. the latter he refers to a subsidence of a portion of the mountain. he divides the rocks of etna into six orders: . the lowest basis of the mountain would appear to consist of granite, because masses of that rock have from time to time been ejected. . calcareous and arenaceous rocks, of which the mountains surrounding etna are composed, and which appear capped with lava near bronte and elsewhere. . basaltic rocks, which are met with near motta s. anastasia, paterno, licodia, and aderno, and in the isole de'ciclopi. . rolled pebbles, which form a range of slightly rising ground between the first slopes of etna on the southern side and the plain of catania. (lyell speaks of this rising ground as consisting of "argillaceous and sandy beds with marine shells, nearly all of living mediterranean species, and with associated and contemporaneous volcanic rocks.") . ancient lavas forming the escarpments around the val del bove; and th, modern lavas. he considers that the fissures which abound on etna are shifts or faults produced by dislocation, and that the minor cones are points along such fissures from which ashes and lava have been ejected. he admits the existence of two cones. the geological map of etna prepared by m. elie de beaumont to accompany his memoir can scarcely be regarded as a great addition to our knowledge of the mountain. for although in the main points it is correct, so many details have been omitted that the map must be considered to have now been quite superseded by those of von waltershausen and friedrich hoffmann. [ ] "récherches sur la structure et sur l'origine du mont etna." . the most convenient geological map of the mountain is without doubt that of hoffmann, given in the _vulkanen atlas_ of dr. von leonhard; and here reproduced. von waltershausen's geological map has been the foundation of all others which have subsequently appeared. it is a marvel of accurate work, and patient industry. the form however is inconvenient, as it nowhere appears as a whole, but in separate portions, which are scattered through the folio sheets of the very expensive _atlas des aetna_. it is accurate, and at the same time very clear and intelligible. by reference to the map it will be seen that from capo di schiso westward, to near paterno, etna is surrounded by sandstone hills; at the south we have recent clays, and, at intervals, chalk. a large triangular space having the two angles at its base, respectively near maletto and aderno, and its apex at the great crater, is covered with new lava; while around nicolosi there is volcanic sand. at the isole de'ciclopi, motta s. anastasia, and a few other places, basalt is seen; on each side of the val del bove, dolerite; and near misterbianco and piedemonte, small deposits of clay slate. the great mass of the surface of the mountain, not specially mentioned above, is volcanic tuff. [illustration: map of the val del bove, to illustrate the theory of a double axis of eruption. (_lyell_).] among the more important and recent additions to our knowledge of the geology of etna may be mentioned lyell's paper on the subject, communicated to the royal society in , the matter of which is incorporated in a lengthy chapter on etna in the "principles of geology." lyell visited the mountain in , , and , and he then collected together a great number of personal observations; he also made use of the maps and plans of von waltershausen, and he has analysed the views of elie de beaumont and other writers. he alludes at the outset to the numerous minor cones of etna produced by lateral eruption, and points out the fact that they are gradually obliterated by the lava descending from the upper part of the mountain, which flows around them and heightens the ground on which they stand. in this way the crater of monte nocilla is now level with the plain, and the crater of monte capreolo was nearly filled by a lava stream in . thus without doubt beneath the sloping sides of etna a multitude of obliterated monticules exist. [illustration: ideal section of mount etna] the strata which surround mount etna on the south are of newer pliocene date, and contain shells which are nearly all of species still living in the mediterranean. out of sixty-five species collected by lyell in , sixty-one were found to belong to species still common in the mediterranean. these strata are about the age of the norwich crag; and the oldest eruptions of etna must have taken place during the glacial period, but before the period of greatest cold in northern europe. before visiting etna, lyell had been told by dr. buckland that in his opinion the val del bove was the most interesting part of etna, accordingly he specially and minutely examined that part of the mountain. this vast valley is situated on the eastern flanks of the mountain, and it commences near the base of the cone, stretching for nearly five miles downwards. it is a large oval basin formed in the side of the mountain, and surrounded by vast precipices, some of which at the head of the valley are between three and four thousand feet in height. the surface is covered with lava of various dates, and several minor cones, notably those of , are within its boundaries. the abrupt precipices reveal the presence of a large number of vertical dikes, radiating from a point within the valley, some of them, according to von waltershausen, being of ancient greenstone. other dikes of more modern doleritic lava radiate from the present crater. from the slope of the beds in the val del bove, lyell and von waltershausen have independently inferred that there was once a second great centre of eruption in the val del bove between the sierra giannicola, and zoccolaro (_vide_ the figure on p. ). the axis of eruption passing through this point lyell calls the _axis of trifoglietto_; while he distinguishes the present centre of eruption as the _axis of mongibello_. these centres probably existed simultaneously, but were unequal as regards eruptive violence; the crater of mongibello was the more active of the two, and eventually overwhelmed the crater of trifoglietto with its products, by which means the whole mountain became a fairly symmetrical cone, having the crater of mongibello at its apex (_vide_ the figures on pp. and ). subsequently the val del bove was formed, probably by some paroxysmal explosion, caused by pent-up gases escaping from fissures. possibly also subsidence may have occurred. [illustration: profile of etna] we must then in the first place think of etna as a submarine volcano of the newer pliocene age; when it reached the surface it increased rapidly in bulk by pouring out scoriæ and lava from its two centres of eruption--the centre of mongibello, and the centre of trifoglietto,--general upheaval of the surrounding district followed, and ultimately the crater of trifoglietto was obliterated by the discharges from the crater of mongibello. afterwards the val del bove was blown out by sudden eruptive force from beneath, and the mountain assumed its present aspect. then the historical eruptions commenced, and of these we have given an account in the preceding chapter. the most obvious method of obtaining some idea as to the age of etna, is to ascertain the thickness of matter added during the historical period to the sides of the mountain, and to compare this with the thickness of the beds of ancient lava and scoriæ exposed at the abrupt precipices of the val del bove. there is reason for believing, however, that none of the ancient lavas equalled in volume the lava streams of and , and the question is much complicated by other considerations. lyell compares the growth of a volcano to that of an exogenous tree, which increases both in bulk and height by the external application of ligneous matter. branches which shoot out from the trunk, first pierce the bark and proceed outwards, but if they die or are broken off they become inclosed in the body of the tree, forming knots in the wood. similarly the volcano consists of a series of conical masses placed one above the other, while the minor cones, corresponding to the branches of the tree, first project, and then become buried again, as successive layers of lava flow around them. but volcanic action is very intermittent, the layers of lava and scoriæ do not accumulate evenly and regularly like the layers of a tree. a violent paroxysmal outbreak may be succeeded by centuries of quiescence, or by a number of ordinary eruptions; or, again, several paroxysmal outbreaks may occur in succession. moreover, each conical envelope of the mountain is made up of a number of distinct currents of lava, and showers of scoriæ. "yet we cannot fail to form the most exalted conception of the antiquity of this mountain, when we consider that its base is about miles in circumference; so that it would require ninety flows of lava, each a mile in breadth at their termination, to raise the present foot of the volcano as much as the average height of one lava current." if all the minor cones now visible on etna could be removed, with all the lava and scoriæ which have ever proceeded from them, the mountain would appear scarcely perceptibly smaller. other cones would reveal themselves beneath those now existing. since the time when, in the newer pliocene period, the foundations of etna were laid in the sea, it is quite impossible even to hint at the number of hundreds of thousands of years which have elapsed. we collected specimens of lava from various points around and upon the mountain. they presented a wonderful similarity of structure, and a mineralogist to whom they were shown remarked that they might almost all have come from the same crater, at the same time. a specimen of the lava of found near borello, was ground by a lapidary until it was sufficiently transparent to be examined under the microscope by polarised light. it was found to contain good crystals of augite and olivine, well striated labradorite, and titaniferous iron ore. elie de beaumont affirms that the lavas of etna consist of labradorite, pyroxene (augite), peridot (olivine), and titaniferous iron. rose was the first to prove that the lavas of etna do not contain ordinary felspar (or potash felspar), but labradorite (or lime felspar.) (_annales des mines_, serie, t. viii., p. .) elie de beaumont detached a quantity of white crystals from the interior of a lava found between giarre and aci reale; these were analysed by m. auguste laurent with the following results in parts:-- silica · alumina · oxide of iron · soda (na{ }o) · potash (k{ }o) · lime · magnesia · ----- · von waltershausen gives the following as the composition of two specimens of labradorite from etna:-- i. ii. silica · · alumina · · sesquioxide of iron · · magnesia · · lime · · soda · · potash · · water · -- ------ ------ · · specimens of augite from etna have been examined by von waltershausen and rammelsberg, with the following results:-- _greenish_ _from_ _from_ _black._ _black._ _mascali._ _monti rossi._ silica · · · · alumina · · · · protoxide of iron · · · · " manganese · -- -- · magnesia · · · · lime · · · · sesquioxide of iron -- -- -- · water · · · · ------ ----- ----- ----- · · · · olivine is generally met with in the lavas of etna. it has an olive, or bottle-glass green colour, and is disseminated through the lavas in the form of small crystalline grains, sometimes of some magnitude. specific gravity · . a specimen from etna gave the following results on analysis:-- silica · protoxide of iron · magnesia · alumina · oxide of nickel · water · ------ · the titaniferous iron of etna is found disseminated through the mass of the lavas, and is plainly distinguished when a thin section is examined under the microscope. it is sometimes met with in masses. a specimen from etna, analysed by von waltershausen, was found to contain:-- titanic acid · sesquioxide of iron · protoxide of iron · ------ · the basalts of the isole de'ciclopi enclose beautiful transparent crystals of analcime, the _zeolite dure_ of dolomieu. the word is derived from ~analkis~ weak, in allusion to the weak electric power which the mineral acquires when heated or rubbed. dana prefers the term _analcite_. specimens from the cyclops islands have been analysed by von waltershausen and rammelsberg, with the following results:-- i. ii. iii. silica · · · alumina · · · lime · · · soda (na{ }o) · · · potash (k{ }o) · · · water · · · magnesia · -- -- sesquioxide of iron -- -- · ----- ------ ------ · · · the minerals of etna are not nearly as numerous as those of vesuvius. it has been remarked that no area of equal size on the face of the globe furnishes so many different species of minerals as vesuvius and its immediate neighbourhood. out of the species of simple minerals enumerated by hauy, no less than had been found on and around vesuvius, as long ago as , and many have been since found. of other common products of etna, there are sulphur in various forms, sulphurous acid gas, ammonia salts, hydrochloric acid gas, and steam. a curious white mass, which we found near the summit, proved to be the result of the decomposition of lava by hot acid vapours. in the different lavas, the crystals of labradorite, and of olivine, vary in size considerably. magnetic oxide of iron is very visible in thin slices of the lavas when placed under the microscope; and iron appears to be a constant constituent in nearly all the products of the mountain. within the last few months prof. silvestri has detected a mineral oil in the cavities of a prehistoric doleritic lava found near paterno.[ ] the lava is in close contiguity to the clay deposits of a mud volcano, and when examined under the microscope is seen to consist mainly of augite, together with olivine and transparent crystals of labradorite. it contains numerous cavities coated with arragonite, and filled with a mineral oil which constitutes about one per cent of the whole weight of the lava. it was taken from the lava at a temperature of ° c., ( · ° f.), and solidified at ° c. ( · ° f.) to a yellowish green mass, which on analysis gave the following percentage composition:-- liquid hydrocarbons boiling at ° c. = · hydrocarbons solidifying below ° c., boiling } between ° and ° c. } = · paraffine melting between ° and ° c. = · asphalt containing per cent of ash = · sulphur = · ------ · [ ] "atti accademia gioenia," serie iii., vol. xii. prof. silvestri has recently made some interesting determinations of the specific gravity and chemical composition of the different products of etna. they are given in full in his work entitled, "_i fenomeni vulcanici presentati dall'etna, nel , , , _," which was published in catania in . the following table gives the specific gravity of various ancient and modern forms of lava, ashes, etc. of etna:-- _sp. gr._ ashes ejected in · sand " " " · scoriæ " " " · compact lava " " · scoriæ ejected in · compact lava " " · lapilli ejected in · compact lava ejected in prehistoric times · a very decided change in the specific gravity was found to take place after fusion. this can only be accounted for on the supposition that a chemical change is effected during the fusion:-- _sp. gr._ _sp. gr._ _before fusion._ _after fusion._ pyroxene of etna · · felspar " " · · olivine " " · · lava of · · ancient basaltic lava from } · · the scogli de'ciclopi } ancient basaltic lava from } · · aci reale } it will be seen from the following analyses that the sand, ashes, scoriæ, and compact lava have virtually the same composition--indeed they consist of the same substance in different states of aggregation. _ashes._ _sand._ _scoriæ._ _compact lava._ silica · · · · alumina · · · · protoxide of iron · · · · protoxide of manganese · · · · lime · · · · magnesia · · · · potash · · · · soda · · · · water · · · · phosphoric acid } titanic acid } traces traces traces traces vanadic acid } sesquioxide of iron } ------ ------ ------ ------ · · · · with these we may compare the composition of the lava which issued from monti rossi in , and was analysed by lowe, and of an ancient lava of etna ejected during an unknown eruption, and analysed by hesser. _ancient lava._ _lava of ._ silica · · alumina · · protoxide of iron · · protoxide of manganese · · lime · · magnesia · · soda · · potash · · ----- ----- · · the sublimations from the fumaroles are chiefly chloride of ammonium, perchloride of iron, and sulphur. an analysis of the gases of the fumaroles of gave the following results:-- carbonic acid · hydrosulphuric acid · oxygen · nitrogen · ----- · an account of microscopic analysis of some of the lavas of etna, for which i am indebted to mr. frank rutley, will be found appended to this chapter. he considers that they are plagioclase-basalts, and occasionally olivine-basalts; and that they consist of plagioclase, augite, olivine, magnetite, titaniferous iron, and a residuum of glass. near the summit of the great crater i found a mass of perfectly white, vesicular, and very friable substance, somewhat pumiceous in appearance. it proved to be a decomposed lava, and was found elsewhere on the sides of the crater. mr. rutley examined a section of it, and reports: "under the microscope a tolerably thin section shows the outlines of felspar crystals, lying in a hazy milk-white semi-opaque granular matrix. the felspar crystals are lighter and more translucent than the matrix, but are of much the same character, having a granulated or flocculent appearance, somewhat like that of the decomposed felspars in diabase. there are numerous roundish cavities in the section which may once have contained olivine, or some other mineral, or they may be merely vesicles." a qualitative analysis of this substance, made by mr. h. m. elder, has proved that it contains a large quantity of silica (about per cent.), and smaller proportions of alumina, iron, magnesium, calcium, and potash; together with very small amounts of sulphuric acid and a trace of ammonia. lithium is absent, and sodium is only present in very minute quantity. water is present to the extent of nearly per cent. during the eruption of etna in von waltershausen noticed on some of the lava blocks which were still hot and smoking, silver-coloured particles, which rapidly underwent change. an insufficient quantity for analysis was collected, but during the eruption of , silvestri found a quantity of the substance and analysed it. (_poggendorff's annalen_, clvii. , .) it possesses a specific gravity of · , and shows a metallic lustre similar to that of steel. on analysis it was found to consist of:-- iron · nitrogen · ------ · which corresponds with the formula fe{ }n{ },--a formula assigned by fremy to nitride of iron. it has been named _siderazote_. this new mineral species appears to be formed by the action of hydrochloric acid, and of ammonia on red-hot lava containing a large percentage of iron. it was formed artificially by exposing fragments of lava alternately to the action of hydrochloric acid and ammonia in a red-hot tube. at a high temperature siderazote undergoes decomposition, nitrogen being evolved. in contact with steam at a red heat it forms magnetite and ammonia. _the mineral constitution and microscopic characters of some of the lavas of etna._ by frank rutley, f.r.g.s., of h.m. geological survey. a cursory examination of the series of specimens collected by mr. rodwell, seemed to show that all the lavas of etna, irrespective of their differences in age, exhibit a remarkable similarity in mineralogical constitution. occasionally, however, there appears to have been a little difference in their respective viscidity at the time of the eruption, the crystals in some of them lying in all directions, while in others there appears to be a more or less definite arrangement of the felspar crystals, as seen in the lava of a.d. . although the specimens which i have examined microscopically do not appear to differ in the nature of their constituents, yet in some of them certain minerals fluctuate in quantity, some containing a comparatively large amount of olivine and well-developed crystals of augite, while, in others, these minerals, although one or other is always present, are but poorly represented by minute and sparsely-disseminated grains. it seems probable that all the etna lavas contain traces of a vitreous residuum, since, when sections are examined under the microscope, a more or less general darkness pervades their ground mass as soon as the nicols are crossed, and this general darkness does not appear to be dissipated during the horizontal revolution of the sections themselves. the translucent minerals in these sections are all doubly refracting, and as i have not been able to detect the presence of hauyne, noseau, sodalite, analcime, or any other cubic mineral in them, the natural inference is that the obscurity between crossed nicols is due to amorphous matter. i have only been able to ascertain the presence of glass distinctly in a microscopic section of the lava of salto di pulichello. in the other sections which i have examined there appears to be a small quantity of interstitial glass, but it is so finely disseminated between the microliths of felspar and granules of olivine, augite and magnetite, which constitute the ground-mass of these rocks, that it is most difficult to determine the single refraction of such minute specks during revolution between crossed nicols, and i therefore merely express a belief, which, in some instances, i cannot demonstrate with any certainty. [illustration: sections of etna lavas seen under the microscope] plagioclastic felspars are unquestionably the dominant constituents of these lavas. lyell, in his "principles of geology," ( th edition, p. ), states that the felspar is labradorite. he does not, however, give the grounds for this conclusion, and, as microscopic examination alone merely indicates the crystalline system and not the species of felspar, it is unsafe to speculate upon this point in the absence of chemical investigation. in some of these lavas sanidine is also present, but it is always subordinate to the plagioclase, and does not, as a rule, appear to play a part sufficiently prominent to entitle the rock to the appellation trachy-dolerite. augite and olivine are generally present in the etna lavas, especially the latter mineral. magnetite appears to occur in all of them. titaniferous iron may also be represented, but i have failed to detect any well-defined crystals, or any traces of the characteristic white decomposition product which would justify me in citing the presence of this mineral, although it is stated by lyell to occur in these rocks. the constituent minerals of the etna lavas now to be described, namely, those of b.c. and a.d. , and , are:-- plagioclase, augite, olivine, magnetite, and, in some cases, sanidine--possibly titaniferous iron--and in some, if not in all, a slight residuum of glass. these lavas must therefore be regarded as plagioclase-basalts, or occasionally as olivine-basalts. the plagioclase crystals vary greatly in size, some being mere microliths while others are over the eighth of an inch in length. they show the characteristic twin lamellation by polarized light, but the lamellæ are often very irregular as regards their boundaries. the sections of the crystals themselves are also frequently bounded by irregular outlines, but they often show internally delicate zonal markings, as indicated in fig. ,[ ] which correspond with the outlines of perfectly developed crystals. the inclosures in the larger plagioclastic felspars consist for the most part either of brownish glass, containing fine dark granular matter--probably magnetite, which often renders them opaque,--or of matter similar to that which constitutes the groundmass of the surrounding rock. these stone and glass cavities are very numerous and most irregular in outline, as shown in figs. and . they appear, however, to be elongated generally in the direction of the planes of composition of the twin lamellæ. zirkel has noted the plentiful occurrence of these glass inclosures in the felspar crystals and fragments of crystals which partly constitute the volcanic sands of etna, in which he has also detected the presence of numerous isolated particles of brownish glass.[ ] the felspar microliths, which constitute so large a proportion of the ground-mass in the etna lavas, are in most instances probably triclinic. monoclinic felspar does, however, occur in some of these rocks; but the difficulty of ascertaining the precise character of microliths renders it unsafe to speculate on the amount of sanidine which may be present. some crystals, such as that shown in the centre of fig. , appear at first sight to be sanidine, twinned on the carlsbad type, but closer inspection often demonstrates the presence of other and very delicate twin lamellæ. [ ] _the figures in this plate are magnified diameters._ fig. . lava of b.c. . the upper half of the drawing is occupied by a crystal of plagioclastic felspar showing twin lamellation and faint zonal markings, and with numerous irregular dark-brown inclosures of glass, probably containing magnetite dust and matter similar to that of the groundmass of the rock which consists of felspar microliths, granules of olivine, and augite crystals, grains of magnetite, and apparently a little interstitial glass. a crystal of augite is shown near the bottom of the drawing. fig. . lava of a.d. . on the right hand side part of a plagioclase crystal with inclosures similar to that in the preceding figure. in the centre a small crystal of plagioclase. groundmass similar to that of fig. , but showing a somewhat definite arrangement of the small felspar crystals, indicative of fluxion. [ ] "mikroskopische beschaffenheit der mineralien und gesteine." leipzig, ; p. . the augite in these lavas sometimes occurs in well-formed crystals of a green or brown colour, and often shows the characteristic cleavage very well, especially in the augite crystals of the lava of the boccarelle del fuoco, erupted in . a small crystal of green augite is represented at the bottom of fig. . augite, however, appears to be more plentiful in the rocks in the form of small roundish grains. olivine is of very common occurrence in the etna lavas, mostly in round or irregularly shaped grains, but also in crystals which usually exhibit rounded angles. a specimen of lava from salto di pulichello, erupted in , gave well-developed examples of the presence of olivine, and also of plagioclase. the ground mass was found to consist of felspar microliths, and grains of olivine, augite, and magnetite, with some interstitial glass. magnetite is present in all of the lavas here described. it occurs both in octahedral crystals and in the form of irregular grains and fine dust. to the presence of this substance much of the opacity of thin sections of the etna lavas is due. titaniferous iron may also be present. one small crystal in the lava of appeared to show a somewhat characteristic form, but although much of the black opaque matter has undergone decomposition, i have failed to detect any of the white or greyish alteration product which characterises titaniferous iron, and in the absence of this, of definite crystalline form, and of chemical analysis, it seems better to speak of this mineral with reserve, although titanium is very probably present, since much magnetite is known to be titaniferous. the vitreous matter which occurs in these lavas is principally present in the form of inclosures in the felspar, and, sometimes, the augite and olivine crystals previously described. its occurrence in the groundmass of these rocks has also been alluded to. in this interstitial condition its amount is usually very small--a fact already pointed out by zirkel. i have unfortunately had no opportunity of examining the volcanic sands and ashes of etna, but zirkel's description of them seems to indicate their close mineralogical relation to lavas erupted in this district, with one exception, as pointed out by rosenbusch,[ ] namely, that he makes no mention of the occurrence of olivine in these ejectamenta. [ ] "mikroskopische physiographie der massigen gesteine. stuttgart, ; p. . reference to the figures and will suffice to show how close a relationship in mineral constitution exists between these two lavas, separated in the dates of their eruption by an interval of over two thousand years. * * * * * _new maps of etna._--after these pages had received their final revision in type, i met with two new maps of etna in the paris exhibition. the literature of our subject will obviously be incomplete without some notice of them, although this belongs properly to the first chapter rather than to the last. the one is a map in relief constructed by captain francesco pistoja for the _istituto topografico militare_ of florence. the vertical scale is / , and the horizontal is / , . the surface is coloured geologically: the lavas erupted during each century being differently coloured, while the course of each stream is traced. this map, although by no means free from errors, is a vast improvement on the relief map of m. elie de beaumont. one defect, which might be easily remedied, is due to the fact that the lavas of three consecutive centuries are coloured so much alike, that it is almost impossible to distinguish them. the minor cones are well shown, the val del bove fairly well, and the map is altogether a valuable addition to our knowledge of the mountain. the other map is a _carta agronomica dell' etna_, showing the surface cultivation. different colours denote different plants, pistachio nuts, vines, olives, chestnuts, etc. it is beautifully drawn and coloured by hand, and is the work of signor l. ardini, of catania. index. abich, acesines, river, aci reale, , acis, river, acque grande, aderno, adranum, city of, Æschylus, aetna, town of, ajo, fountain of, alcantara, valley of, amphinomus, analcime, analysis of, analcite, analysis of augite, " " labradorite, , " " olivine, " " titaniferous iron, " " analcime, " " mineral oil, " " volcanic ashes, " " lava, , " " sand, " " scoriæ, " microscopic, of lavas, - " " siderazote, , " " sublimations, " " white friable substance, anapias, arethusa, fountain of, ascent, fatigue of, ashes, volcanic, analysis of, " " specific gravity of, atlas des aetna, augite, analysis of, axis of mongibello, , " " trifoglietto, , baltzer, basalt, columnar, base, circumference of, belpasso, bembo, cardinal, biancavilla, boccarelle del fuoco, bocche eruttive, " del fuoco, borelli, bosco di bronte, botanical regions, - boundaries of etna, brilliancy of stars, , bronte, , brydone, campi phlegræi, campus piorum, cardinal bembo, carpinetto, forest of, carrera, casa del bosco, " inglesi, , castagno di cento cavalli, " della galea, catania, - " destruction of, - caverns of etna, cavern of thalia, centenario, chestnuts, circumference of base, cisterna, coltivata, regione, , cones, minor, - crater of elevation, " of eruption, " the great, - craters, minor, - cultivated region, cyclops, rocks of, decomposed lava, analysis of, desert region, , effects of refraction, , elevation, crater of, elie de beaumont, elie de beaumont's classification, , empedokles, errors in maps, eruption, crater of, eruptions, general character of, " number of, etna, the home of early myths, " a submarine volcano, enceladus, fatigue of ascent, fazzello, ferrara, , filoteo, flood of , forest of carpinetto, fratelli pii, cone of, fumaroles, sublimations of, fuoco, regione del, gemellaro, giuseppe, " mario, " carlo, , general aspect of etna, _genista etnensis_, geological maps of etna, - gibel uttamat, gladstone's account of eruption, gravity, specific, of ejectamenta, great crater, , grotto of polyphemus, " delle palombe, growth of a volcano, gurrita, lake, hamilton, height of etna, , hephaistos, forge of, himilco, hoffmann, homer, houel, hybla major, increase of population, inessa, city of, inglesi, casa, , inns, sicilian, , , iron, nitride of, " perchloride of, iron, titaniferous, isola d'aci, katana, , kircher, labradorite, analysis of, , la cisterna, latitude of crater, la scaletta, lava, analysis of, , " specific gravity of, " decomposed, analysis of, lavas, microscopic analysis of, - lavas of etna, - linguaglossa, longitude of crater, lucilius junior, - lucretius, lyell, lyell's researches, - magnetite, maletto, maps, geological, of etna, , " of etna, , , - mascali, microscopic analysis of lavas, - milo, mineral oil in lava, minor cones, - mongibello, " axis of, monte calanna, " capreolo, " di mojo, , " minardo, " ste. sofia, " fusara, " grigio, " lepre, " nocilla, " rosso, " spagnuolo, " ste. sofia, monti rossi, , mules, name of etna, natural boundaries of etna, naxos, newer pliocene strata, nicolosi, nitride of iron, observatory on etna, oil, mineral, in lava, olivine, " analysis of, palombe, grotto delle, paterno, pennisi, baron, , piano del lago, " di s. leo, piedimontana, regione, , pii fratres, , pindar, polarized light, applied to analysis of lavas, - polyphemus, grotto of, population, - position of etna, presl's _flora sicula_, , radius of vision, randazzo, , recupero, recupero's account of eruption, refraction, effects of, , regions of etna, - regione del fuoco, river, acis, road around etna, rocca di musarra, rocks of cyclops, rutley's, mr. frank, analysis of lavas, - st. agatha, veil of, " maria di licodia, s. niccola, monastery of, s. simone, salto della guimenta, sand, volcanic, analysis of, " specific gravity of, scogli di ciclopi, scoriæ, volcanic, analysis of, " specific gravity of, serra delle concazze, " del solfizio, " di giannicola, serrapizzuta, sicilian inns, , , siderazote, , silvestri, researches of, simeto, valley of, smyth, smyth's observations, snow of etna, specific gravity, alteration of, " " of ejectamenta, strabo, stars, brilliancy of, , stato maggiore, map of, sulphur in sublimations, sublimations from fumaroles, summit of cone, , sunrise seen from summit, , tacchini, taormina, tertiary sandstone of bronte, thucydides, titaniferous iron, torre del filosofo, , towns on etna, trezza, trifoglietto, axis of, trunks of large chestnuts, val del bove, , , , , - " serbo, valley of alcantara, virgil, vision, radius of, volcano, growth of, von waltershausen, , vulkanen atlas, winchelsea, lord, , , woody region, _zeolite dure_, zones of temperature, * * * * * transcribers notes: oe ligatures have been written as two letters. the chemical formulae in this text have subscripts written in curly brackets. for example, water appears as h{ }o. passages in italics indicated by _underscores_. passages in greek indicated by ~tildes~. printer's errors corrected and other transcription points as follows: page correction --------------------------------------------------------------------- - some arcane spellings retained where verified as correct for the time of publication or quote, such as 'musquitoes', 'plaintain', 'mettals', 'felspar', etc. - italian quotations sometimes include phrases such as "sull' etna" or "dell' asia". there should be no space after the apostrophes but spaces are often present. this may have been done to better space the text during justification. such errors have not been corrected. - the document is inconsistent in the use of commas where quoting numbers of over , ; sometimes they are used and sometimes they are not used. these inconsistencies remain. ix added '.' at end of 'silvestri' in text block to maintain style of other entries. x added '.' at end of 'eruptions' in text block to maintain style of other entries. x added '.' after ' ' in text block to maintain style of other entries. xi added '.' after 'microscope' in text block to maintain style of other entries. corrected 'ength' to 'length'. corrected 't'jncedie' to 't'incedie'. 't'jncedie' and 'treblement' both printed with tildes over the first occurrence of e in each word. tildes omitted in this version. corrected 'guiseppe' to 'giuseppe'. added end quotes after final word on page. inserted full-stop after '(s.w.)', to end sentence. corrected 'f' to 'of'. 'of-course' corrected to 'of course'. corrected 'unusally' to 'unusually'. corrected 'subsequenly' to 'subsequently'. corrected 'athough' to 'although'. added '.' after ' ' in text block to maintain style of other entries. anapias and amphinomus printed with diacritic marks omitted in this text (breves over first 'a' in 'anapias' and 'i' in 'amphinomus'). numbered list runs , , , , , , , ... second occurrence of amended to . 'in the ' corrected to 'in the year '. 'the time analcite' corrected to 'the term analcite'. corrected 'guiseppe' to 'giuseppe'. corrected 'miscroscope' to 'microscope'. corrected 'magnitite' to 'magnetite'. generously made available by the internet archive/american libraries.) the chemistry, properties and tests of precious stones * * * * * by the same author the stolen planet. ( nd edition.) s. d. through the sun in an airship. s. the immortal light. ( nd edition.) s. c. griffin and co., ltd. the autobiography of a picture. ( nd edition.) s. d. this workaday world. (in the press.) henry j. drane. pepper's boy's playbook of science. (new edition.) now in press, revised, re-written and re-illustrated by dr. john mastin. george routledge and sons, ltd. etc. etc. * * * * * the chemistry, properties and tests of precious stones. by john mastin, m.a. d.sc. ph.d. litt.d. f.s a.scot. f.l.s. f.c.s. f.r.a.s. f.r.m.s. r.b.a. _author of "parasites of insects," "the true analysis of milk," "plate-culture and staining of amoebæ," etc., etc._ _london_ e. & f. n. spon, limited, haymarket _new york_ spon & chamberlain, liberty street transcriber's note: for text: a word surrounded by a cedilla such as ~this~ signifies that the word is bolded in the text. a word surrounded by underscores like _this_ signifies the word is italics in the text. the italic and bold markup for single italized letters or "foreign" abbreviations are deleted for easier reading. for numbers and equations: parentheses have been added to clarify fractions. underscores before bracketed numbers in equations denote a subscript. contents chapter page i introductory ii the origin of precious stones iii physical properties--(a) crystalline structure iv " " (b) cleavage v " " (c) light vi " " (d) colour vii " " (e) hardness viii " " (f) specific gravity ix " " (g) heat x " " (h) magnetic and electric influences xi the cutting of precious stones xii imitations, and some of the tests of precious stones xiii various precious stones xiv " " " (_continued_) xv " " " " preface some little time ago certain london diamond merchants and wholesale dealers in precious stones made the suggestion to me to write a work on this section of mineralogy, as there did not appear to be any giving exactly the information most needed. finding there was a call for such a book i have written the present volume in order to meet this want, and i trust that this handbook will prove useful, not only to the expert and to those requiring certain technical information, but also to the general public, whose interest in this entrancing subject may be simply that of pleasure in the purchase, possession, or collection of precious stones, or even in the mere examination of them through the plate-glass of a jeweller's window. john mastin. totley brook, near sheffield. _june ._ the chemistry, properties and tests of precious stones chapter i. introductory. what constitutes a precious stone is the question which, at the onset, rises in the mind, and this question, simple as it seems, is one by no means easy to answer, since what may be considered precious at one time, may cease to be so at another. there are, however, certain minerals which possess distinctive features in their qualities of hardness, colour, transparency, refractability or double refractability to light-beams, which qualities place them in an entirely different class to the minerals of a metallic nature. these particular and non-metallic minerals, therefore, because of their comparative rarity, rise pre-eminently above other minerals, and become actually "precious." this is, at the same time, but a comparative term, for it will readily be understood that in the case of a sudden flooding of the market with one class of stone, even if it should be one hitherto rare and precious, there would be an equally sudden drop in the intrinsic value of the jewel to such an extent as perhaps to wipe it out of the category of precious stones. for instance, rubies were discovered long before diamonds; then when diamonds were found these were considered much more valuable till their abundance made them common, and they became of little account. rubies again asserted their position as chief of all precious stones in value, and in many biblical references rubies are quoted as being the symbol of the very acme of wealth, such as in proverbs, chapter iii., verses and , where there are the passages, "happy is the man that findeth wisdom ... she is more precious than rubies"--and this, notwithstanding the enormous quantity of them at that time obtained from the ruby mines of ophir and nubia, which were then the chief sources of wealth. it will also be remembered that josephus relates how, at the fall of jerusalem, the spoil of gold was so great that syria was inundated with it, and the value of gold there quickly dropped to one-half; other historians, also, speaking of this time, record such a glut of gold, silver, and jewels in syria, as made them of little value, which state continued for some considerable period, till the untold wealth became ruthlessly and wastefully scattered, when the normal values slowly reasserted themselves. amongst so many varieties of these precious minerals, it cannot be otherwise than that there should be important differences in their various characteristics, though for a stone to have the slightest claim to be classed as "precious" it must conform to several at least of the following requirements:--it must withstand the action of light without deterioration of its beauty, lustre, or substance, and it must be of sufficient hardness to retain its form, purity and lustre under the actions of warmth, reasonable wear, and the dust which falls upon it during use; it must not be subject to chemical change, decomposition, disintegration, or other alteration of its substance under exposure to atmospheric air; otherwise it is useless for all practical purposes of adornment or ornamentation. there are certain other characteristics of these curious minerals which may be classified briefly, thus:--some stones owe their beauty to a wonderful play of colour or fire, due to the action of light, quite apart from the colour of the stone itself, and of this series the opal may be taken as a type. in others, this splendid play of colour is altogether absent, the colour being associated with the stone itself, in its substance, the charm lying entirely in the superb transparency, the ruby being taken as an example of this class of stone. others, again, have not only colour, but transparency and lustre, as in the coloured diamonds, whilst the commoner well-known diamonds are extremely rich in transparency and lustre, the play of light alone showing a considerable amount of brilliancy and beauty of colour, though the stone itself is clear. still others are opaque, or semi-opaque, or practically free from play of light and from lustre, owing their value and beauty entirely to their richness of colour. in all cases the value of the stone cannot be appreciated fully till the gem is separated from its matrix and polished, and in some cases, such as in that of the diamond, cut in variously shaped facets, on and amongst which the light rays have power to play; other stones, such as the opal, turquoise and the like, are cut or ground in flat, dome-shaped, or other form, and then merely polished. it frequently happens that only a small portion of even a large stone is of supreme value or purity, the cutter often retaining as his perquisite the smaller pieces and waste. these, if too small for setting, are ground into powder and used to cut and polish other stones. broadly speaking, the greatest claim which a stone can possess in order to be classed as precious is its rarity. to this may be added public opinion, which is led for better or worse by the fashion of the moment. for if the comparatively common amethyst should chance to be made extraordinarily conspicuous by some society leader, it would at once step from its humbler position as semi-precious, and rise to the nobler classification of a truly precious stone, by reason of the demand created for it, which would, in all probability, absorb the available stock to rarity; and this despite the more entrancing beauty of the now rarer stones. the study of this section of mineralogy is one of intense interest, and by understanding the nature, environment, chemical composition and the properties of the stones, possibility of fraud is altogether precluded, and there is induced in the mind--even of those with whom the study of precious stones has no part commercially--an intelligent interest in the sight or association of what might otherwise excite no more than a mere glance of admiration or curiosity. there is scarcely any form of matter, be it liquid, solid, or gaseous, but has yielded or is now yielding up its secrets with more or less freedom to the scientist. by his method of synthesis (which is the scientific name for putting substances together in order to form new compounds out of their union) or of analysis (the decomposing of bodies so as to divide or separate them into substances of less complexity), particularly the latter, he slowly and surely breaks down the substances undergoing examination into their various constituents, reducing these still further till no more reduction is possible, and he arrives at their elements. from their behaviour during the many and varied processes through which they have passed he finds out, with unerring accuracy, the exact proportions of their composition, and, in many cases, the cause of their origin. it may be thought that, knowing all this, it is strange that man does not himself manufacture these rare gems, such as the diamond, but so far he has only succeeded in making a few of microscopic size, altogether useless except as scientific curiosities. the manner in which these minute gems and spurious stones are manufactured, and the methods by which they may readily be distinguished from real, will be dealt with in due course. the natural stones represent the slow chemical action of water, decay, and association with, or near, other chemical substances or elements, combined with the action of millions of years of time, and the unceasing enormous pressure during that time of thousands, perhaps millions, of tons of earth, rock, and the like, subjected, for a certain portion at least of that period, to extremes of heat or cold, all of which determine the nature of the gem. so that only in the earth itself, under strictly natural conditions, can these rare substances be found at all in any workable size; therefore they must be sought after assiduously, with more or less speculative risk. chapter ii. the origin of precious stones. though the origin, formation, composition, characteristics and tests of each stone will be examined in detail when dealing with the stones seriatim, it is necessary to enquire into those particulars of origin which are common to all, in order thoroughly to understand why they differ from other non-metallic and metallic minerals. at the very commencement we are faced with a subject on which mineralogists and geologists are by no means in full agreement, and there seems just ground for considerable divergence of opinion, according to the line of argument taken. it is a most remarkable fact that, precious as are certain stones, they do not (with a few exceptions) contain any of the rarer metals, such as platinum, gold, etc., or any of their compounds, but are composed entirely of the common elements and their derivatives, especially of those elements contained in the upper crust of the earth, and this notwithstanding the fact that gems are often found deep down in the earth. this is very significant, and points to the conclusion that these stones were formed by the slow percolation of water from the surface through the deeper parts of the earth, carrying with it, in solution or suspension, the chemical constituents of the earth's upper crust; time and long-continued pressure, combined with heat or cold, or perhaps both in turn, doing the rest, as already mentioned. the moisture falling in dew and rain becomes acidulated with carbonic acid, co_{ } (carbon dioxide), from the combustion and decay of organic matter, vegetation, and other sources, and this moisture is capable of dissolving certain calcareous substances, which it takes deep into the earth, till the time comes when it enters perhaps a division-plane in some rock, or some such cavity, and is unable to get away. the hollow becomes filled with water, which is slowly more and more charged with the salts brought down, till saturated; then super-saturated, so that the salts become precipitated, or perhaps crystallised out, maybe by the presence of more or other salts, or by a change in temperature. these crystals then become packed hard by further supplies and pressure, till eventually, after the lapse of ages, a natural gem is found, _exactly filling_ the cavity, and is a precious find in many cases. if now we try to find its analogy in chemistry, and for a moment consider the curious behaviour of some well-known salts, under different conditions of temperature, what is taking place underground ceases to be mysterious and becomes readily intelligible. perhaps the best salt for the purpose, and one easy to obtain for experiment, is the sulphate of sodium--known also as glauber's salt. it is in large, colourless prisms, which may soon be dissolved in about three parts of water, so long as the water does not exceed ° f., and at this temperature a super-saturated solution may easily be made. but if the water is heated the salt then becomes more and more insoluble as the temperature increases, till it is completely insoluble. if a super-saturated solution of this glauber's salt is made in a glass, at ordinary atmospheric temperature, and into this cold solution, without heating, is dropped a small crystal of the same salt, there will be caused a rise in temperature, and the whole will then crystallise out quite suddenly; the water will be absorbed, and the whole will solidify into a mass which exactly fits the inner contour of the vessel. we have now formed what _might_ be a precious stone, and no doubt would be, if continuous pressure could be applied to it for perhaps a few thousand years; at any rate, the formation of a natural jewel is not greatly different, and after being subjected for a period, extending to ages, to the washings of moisture, the contact of its containing bed (its later matrix), the action of the changes in the temperature of the earth in its vicinity, it emerges by volcanic eruption, earthquake, landslip and the like, or is discovered as a rare and valuable specimen of some simple compound of earth-crust and water, as simple as glauber's salt, or as the pure crystallized carbon. it is also curious to note that in some cases the stones have not been caused by aqueous deposit in an already existing hollow, but the aqueous infusion has acted on a portion of the rock on which it rested, absorbing the rock, and, as it were, replacing it by its own substance. this is evidenced in cases where gems have been found encrusted on their matrix, which latter was being slowly transformed to the character of the jewel encrusted, or "scabbed" on it. the character of the matrix is also in a great measure the cause of the variety of the stone, for it is obvious that the same salt-charged aqueous solution which undergoes change in and on ironstone would result in an entirely different product from that resting on or embedded in silica. following out the explanation of the aqueous solution, in which the earth-crust constituents are secreted, we find that the rarer and more precious metals do not generally enter into the composition of precious stones--which fact may advisedly be repeated. it is, of course, to be expected that beryllium will be found in the emerald, since it is under the species beryl, and zirconium in zircon; but such instances are the exception, and we may well wonder at the actions of the infinite powers of nature, when we reflect that the rarest, costliest and most beautiful of all precious stones are the simplest in their constituents. thus we find the diamond standing unique amongst all gems in being composed of one element only--carbon--being pure crystallised carbon; a different form from graphite, it is true, but, nevertheless, pure carbon and nothing else. therefore, from its chemical, as well as from its commercial aspect, the diamond stands alone as the most important of gems. the next in simplicity, whilst being the most costly of all, is the ruby, and with this may be classed the blue sapphire, seeing that their chemical constituents are exactly the same, the difference being one of colour only. these have two elements, oxygen and aluminium, which important constituents appear also in other stones, but this example is sufficient to prove their simplicity of origin. another unique stone is the turquoise, in that it is the only rare gem essentially containing a great proportion of water, which renders it easily liable to destruction, as we shall see later. it is a combination of alumina, water, and phosphoric acid, and is also unique in being the only known valuable stone containing a phosphate. turning to the silica series, we again find a number of gems with two elements only, silica--an important constituent of the earth's crust--and oxygen--an important constituent of atmospheric air. in this group may be mentioned the opal, amethyst, agate, rock-crystal, and the like, as the best known examples, whilst oxygen appears also mostly in the form of oxides, in chrysoberyl, spinel, and the like. this silica group is extremely interesting, for in it, with the exception of the tourmaline and a few others, the composition of the gems is very simple, and we find in this group such stones as the chrysolite, several varieties of topaz, the garnet, emerald, etc., etc. malachite and similar stones are more ornamental than precious, though they come in the category of precious stones. these are the carbonate series, containing much carbonic acid, and, as may be expected, a considerable proportion of water in their composition, which water can, of course, be dispelled by the application of heat, but to the destruction of the stone. from all this will be seen how strong is the theory of aqueous percolation, for, given time and pressure, water charged with earth-crust constituents appears to be the origin of the formation of all precious stones; and all the precious stones known have, when analysed, been found to be almost exclusively composed of upper-earth-crust constituents; the other compounds which certain stones contain may, in all cases, be traced to their matrix, or to their geological or mineralogical situation. in contradistinction to this, the essentially underground liquids, with time and pressure, form metallic minerals and mineralise the rocks, instead of forming gems. thus we see that in a different class of minerals--compounds of metals with the sulphates, such as sulphuric acid and compounds; also those containing the metallic sulphides; in cases where the metalliferous ores or the metallic elements enter into composition with the halogens--bromine, chlorine, fluorine, and iodine--in all these, precious stones are comparatively common, but the stones of these groups are invariably those used for decorative or ornamental purposes, and true "gems" are entirely absent. it would therefore appear that though metallic minerals, as already mentioned, are formed by the action of essentially _underground_ chemically-charged water--combined with ages of time and long-continued pressure, rocks and earth being transformed into metalliferous ores by the same means--precious stones (or that portion of them ranking as jewels or gems) must on the contrary be wholly, or almost wholly, composed of _upper_-earth-crust materials, carried deep down by water, and subjected to the action of the same time and pressure; the simpler the compound, the more perfect and important the result, as seen in the diamond, the ruby, and the like. chapter iii. physical properties. a--crystalline structure. before proceeding to the study of precious stones as individual gems, certain physical properties common to all must be discussed, in order to bring the gems into separate classes, not only because of some chemical uniformity, but also because of the unity which exists between their physical formation and properties. the first consideration, therefore, may advisedly be that of their crystals, since their crystalline structure forms a ready means for the classification of stones, and indeed for that of a multitudinous variety of substances. it is one of the many marvellous phenomena of nature that mineral, as well as many vegetable and animal substances, on entering into a state of solidity, take upon themselves a definite form called a crystal. these crystals build themselves round an axis or axes with wonderful regularity, and it has been found, speaking broadly, that the same substance gives the same crystal, no matter how its character may be altered by colour or other means. even when mixed with other crystallisable substances, the resulting crystals may partake of the two varieties and become a sort of composite, yet to the physicist they are read like an open book, and when separated by analysis they at once revert to their original form. on this property the analyst depends largely for his results, for in such matters as food adulteration, etc., the microscope unerringly reveals impurities by means of the crystals alone, apart from other evidences. it is most curious, too, to note that no matter how large a crystal may be, when reduced even to small size it will be found that the crystals are still of the same shape. if this process is taken still further, and the substance is ground to the finest impalpable powder, as fine as floating dust, when placed under the microscope each speck, though perhaps invisible to the naked eye, will be seen a perfect crystal, of the identical shape as that from which it came, one so large maybe that its planes and angles might have been measured and defined by rule and compass. this shows how impossible it is to alter the shape of a crystal. we may dissolve it, pour the solution into any shaped vessel or mould we desire, recrystallise it and obtain a solid sphere, triangle, square, or any other form; it is also possible, in many cases, to squeeze the crystal by pressure into a tablet, or any form we choose, but in each case we have merely altered the _arrangement_ of the crystals, so as to produce a differently shaped _mass_, the crystals themselves remaining individually as before. such can be said to be one of the laws of crystals, and as it is found that every substance has its own form of crystal, a science, or branch of mineralogy, has arisen, called "crystallography," and out of the conglomeration of confused forms there have been evolved certain rules of comparison by which all known crystals may be classed in certain groups. this is not so laborious a matter as would appear, for if we take a substance which crystallises in a cube we find it is possible to draw nine symmetrical planes, these being called "planes of symmetry," the intersections of one or more of which planes being called "axes of symmetry." so that in the nine planes of symmetry of the cube we get three axes, each running through to the opposite side of the cube. one will be through the centre of a face to the opposite face; a second will be through the centre of one edge diagonally; the third will be found in a line running diagonally from one point to its opposite. on turning the cube on these three axes--as, for example, a long needle running through a cube of soap--we shall find that four of the six identical faces of the cube are exposed to view during each revolution of the cube on the needle or axis. these faces are not necessarily, or always, planes, or flat, strictly speaking, but are often more or less curved, according to the shape of the crystal, taking certain characteristic forms, such as the square, various forms of triangles, the rectangle, etc., and though the crystals may be a combination of several forms, all the faces of any particular form are similar. all the crystals at present known exhibit differences in their planes, axes and lines of symmetry, and on careful comparison many of them are found to have some features in common; so that when they are sorted out it is seen that they are capable of being classified into thirty-three groups. many of these groups are analogous, so that on analysing them still further we find that all the known crystals may be classed in six separate systems according to their planes of symmetry, and all stones of the same class, no matter what their variety or complexity may be, show forms of the same group. beginning with the highest, we have--( ) the cubic system, with nine planes of symmetry; ( ) the hexagonal, with seven planes; ( ) the tetragonal, with five planes; ( ) the rhombic, with three planes; ( ) the monoclinic, with one plane; ( ) the triclinic, with no plane of symmetry at all. in the first, the cubic--called also the isometric, monometric, or regular--there are, as we have seen, three axes, all at right angles, all of them being equal. the second, the hexagonal system--called also the rhombohedral--is different from the others in having four axes, three of them equal and in one plane and all at ° to each other; the fourth axis is not always equal to these three. it may be, and often is, longer or shorter. it passes through the intersecting point of the three others, and is perpendicular or at right angles to them. the third of the six systems enumerated above, the tetragonal--or the quadratic, square prismatic, dimetric, or pyramidal--system has three axes like the cubic, but, in this case, though they are all at right angles, two only of them are equal, the third, consequently, unequal. the vertical or principal axis is often much longer or shorter in this group, but the other two are always equal and lie in the horizontal plane, at right angles to each other, and at right angles to the vertical axis. the fourth system, the rhombic--or orthorhombic, or prismatic, or trimetric--has, like the tetragonal, three axes; but in this case, none of them are equal, though the two lateral axes are at right angles to each other, and to the vertical axis, which may vary in length, more so even than the other two. the fifth, the monoclinic--or clinorhombic, monosymmetric, or oblique--system, has also three axes, all of them unequal. the two lateral axes are at right angles to each other, but the principal or vertical axis, which passes through the point of intersection of the two lateral axes, is only at right angles to one of them. in the sixth and last system, the triclinic--or anorthic, or asymmetric--the axes are again three, but in this case, none of them are equal and none at right angles. it is difficult to explain these various systems without drawings, and the foregoing may seem unnecessarily technical. it is, however, essential that these particulars should be clearly stated in order thoroughly to understand how stones, especially uncut stones, are classified. these various groups must also be referred to when dealing with the action of light and other matters, for in one or other of them most stones are placed, notwithstanding great differences in hue and character; thus all stones exhibiting the same crystalline structure as the diamond are placed in the same group. further, when the methods of testing come to be dealt with, it will be seen that these particulars of grouping form a certain means of testing stones and of distinguishing spurious from real. for if a stone is offered as a real gem (the true stone being known to lie in the highest or cubic system), it follows that should examination prove the stone to be in the sixth system, then, no matter how coloured or cut, no matter how perfect the imitation, the test of its crystalline structure stamps it readily as false beyond all shadow of doubt--for as we have seen, no human means have as yet been forthcoming by which the crystals can be changed in form, only in arrangement, for a diamond crystal _is_ a diamond crystal, be it in a large mass, like the brightest and largest gem so far discovered--the great cullinan diamond--or the tiniest grain of microscopic diamond-dust, and so on with all precious stones. so that in future references, to avoid repetition, these groups will be referred to as group , , and so on, as detailed here. chapter iv. physical properties. b--cleavage. by cleavage is meant the manner in which minerals separate or split off with regularity. the difference between a break or fracture and a "cleave," is that the former may be anywhere throughout the substance of the broken body, with an extremely remote chance of another fracture being identical in form, whereas in the latter, when a body is "cleaved," the fractured part is more readily severed, and usually takes a similar if not an actually identical form in the divided surface of each piece severed. thus we find a piece of wood may be "broken" or "chopped" when fractured across the grain, no two fractured edges being alike; but, strictly speaking, we only "cleave" wood when we "split" it with the grain, or, in scientific language, along the line of cleavage, and then we find many pieces with their divided surfaces identical. so that when wood is "broken," or "chopped," we obtain pieces of any width or thickness, with no manner of regularity of fracture, but when "cleaved," we obtain strips which are often perfectly parallel, that is, of equal thickness throughout their whole length, and of such uniformity of surface that it is difficult or even impossible to distinguish one strip from another. advantage is taken of these lines of cleavage to procure long and extremely thin even strips from trees of the willow variety for such trades as basket-making. the same effect is seen in house-coal, which may easily be split the way of the grain (on the lines of cleavage), but is much more difficult and requires greater force to break across the grain. rocks also show distinct lines of cleavage, and are more readily split one way than another, the line of cleavage or stratum of break being at any angle and not necessarily parallel to its bed. a striking example of this is seen in slate, which may be split in plates, or laminæ, with great facility, though this property is the result of the pressure to which the rock has been for ages subjected, which has caused a change in the molecules, rather than by "cleavage" as the term is strictly understood, and as existing in minerals. mica is also another example of laminated cleavage, for given care, and a thin, fine knife to divide the plates, this mineral may be "cleaved" to such remarkably thin sheets as to be unable to sustain the most delicate touch without shattering. these are well-known examples of simple cleavage, in one definite direction, though in many instances there are several forms and directions of cleavage, but even in these there is generally one part or line in and on which cleavage will take place much more readily than on the others, these planes or lines also showing different properties and angular characters, which, no matter how much fractured, always remain the same. it is this "cleavage" which causes a crystal to reproduce itself exactly, as explained in the last chapter, showing its parent form, shape and characteristics with microscopic perfection, but more and more in miniature as its size is reduced. this may clearly be seen by taking a very small quantity of such a substance as chlorate of potash. if a crystal of this is examined under a magnifying glass till its crystalline form and structure are familiar, and it is then placed in a test-tube and gently heated, cleavage will at once be evident. with a little crackling, the chlorate splits itself into many crystals along its chief lines of cleavage (called the cleavage planes), every one of which crystals showing under the microscope the identical form and characteristics of the larger crystal from which it came. the cleavage of minerals must, therefore, be considered as a part of their crystalline structure, since this is caused by cleavage, so that both cleavage and crystalline structure should be considered together. thus we see that given an unchangeable crystal with cleavage planes evident, it is possible easily to reproduce the same form over and over again by splitting, whereas by simply breaking, the form of the crystal would be lost; just as a rhomb of iceland spar might be sawn or broken across the middle and its form lost, although this would really be more apparent than real, since it would be an alteration in the mass and not in the shape of each individual crystal. and given further cleavage, by time or a sudden breaking down, even the mass, as mass, would eventually become split into smaller but perfect rhombs. much skill is, therefore, required in cutting and fashioning a precious stone, otherwise the gem may be ruined at the onset, for it will only divide along its lines of cleavage, and any mistake in deciding upon these, would "break," not "split" the stone, and destroy the beauty of its crystalline structure. an example of this was specially seen in the great cullinan diamond, the splitting of which was perhaps the most thrilling moment in the history of precious stones.[a] the value of the enormous crystal was almost beyond computation, but it had a flaw in the centre, and in order to cut out this flaw it was necessary to divide the stone into two pieces. the planes of cleavage were worked out, the diamond was sawn a little, when the operator, acknowledged to be the greatest living expert, inserted a knife in the saw-mark, and with the second blow of a steel rod, the marvellous stone parted precisely as intended, cutting the flaw exactly in two, leaving half of it on the outside of each divided portion. the slightest miscalculation would have meant enormous loss, if not ruin, to the stone, but the greatest feat the world has ever known in the splitting of a priceless diamond was accomplished successfully by this skilful expert in an amsterdam workroom in february, . some idea of the risk involved may be gathered from the fact that this stone, the largest ever discovered, in the rough weighed nearly , carats, its value being almost anything one cared to state--incalculable. [footnote a: the hammer and knife used in cutting the diamond, the two largest pieces of which are now called "the stars of africa," together with a model of the great uncut stone, are in the tower of london amongst the regalia.] these cleavage planes help considerably in the bringing of the stone to shape, for in a broad sense, a finished cut stone may be said to be in the form in which its cleavages bring it. particularly is this seen in the diamond "brilliant," which plainly evidences the four cleavage planes. these cleavage planes and their number are a simple means of identification of precious stones, though those possessing distinct and ready cleavages are extremely liable to "start" or "split" on these planes by extremes of heat and cold, accidental blows, sudden shocks and the like. in stones possessing certain crystalline structure, the cleavage planes are the readiest, often the only, means of identification, especially when the stones are chemically coloured to imitate a more valuable stone. in such cases the cleavage of one stone is often of paramount importance in testing the cleavage of another, as is seen in the perfection of the cleavage planes of calcite, which is used in the polariscope. it sometimes happens, however, that false conditions arise, such as in substances which are of no form or shape, and are in all respects and directions without regular structure and show no crystallisation even in the minutest particles; these are called amorphous. such a condition sometimes enters wholly or partially into the crystalline structure, and the mineral loses its true form, possessing instead the form of crystals, but without a crystalline structure. it is then called a pseudomorph, which is a term applied to any mineral which, instead of having the form it should possess, shows the form of something which has altered its structure completely, and then disappeared. for instance: very often, in a certain cavity, fluorspar has existed originally, but, through some chemical means, has been slowly changed to quartz, so that, as crystals cannot be changed in shape, we find quartz existing--undeniably quartz--yet possessing the crystals of fluorspar; therefore the quartz becomes a pseudomorph, the condition being an example of what is termed pseudomorphism. the actual cause of this curious chemical change or substitution is not known with certainty, but it is interesting to note the conditions in which such changes do occur. it is found that in some cases, the matrix of a certain shaped crystal may, after the crystal is dissolved or taken away, become filled by some other and foreign substance, perhaps in liquid form; or a crystalline substance may become coated or "invested" by another foreign substance, which thus takes its shape; or actual chemical change takes place by means of an incoming substance which slowly alters the original substance, so that eventually each is false and both become pseudomorphs. this curious change often takes place with precious stones, as well as with other minerals, and to such an extent that it sometimes becomes difficult to say what the stone ought really to be called. pseudomorphs are, however, comparatively easy of isolation and detection, being more or less rounded in their crystalline form, instead of having sharp, well-defined angles and edges; their surfaces also are not good. these stones are of little value, except in the specially curious examples, when they become rare more by reason of their curiosity than by their utility as gems. some also show cleavage planes of two or more systems, and others show a crystalline structure comprised of several systems. thus calcspar is in the nd, or hexagonal, whilst aragonite is in the th, the rhombic, system, yet both are the same substance, viz.:--carbonate of lime. such a condition is called dimorphism; those minerals which crystallise in three systems are said to be trimorphous. those in a number of systems are polymorphous, and of these sulphur may be taken as an example, since it possesses thirty or more modifications of its crystalline structure, though some authorities eliminate nearly all these, and, since it is most frequently in either the th (rhombic) or the th (monoclinic) systems, consider it as an example of dimorphism, rather than polymorphism. these varieties of cleavage affect the character, beauty and usefulness of the stone to a remarkable extent, and at the same time form a means of ready and certain identification and classification. chapter v. physical properties. c--light. probably the most important of the many important physical properties possessed by precious stones are those of light and its effects, for to these all known gems owe their beauty, if not actual fascination. when light strikes a cut or polished stone, one or more of the following effects are observed:--it may be transmitted through the stone, diaphaneity, as it is called; it may produce single or double refraction, or polarisation; if reflected, it may produce lustre or colour; or it may produce phosphorescence; so that light may be ( ) transmitted; ( ) reflected; or produce ( ) phosphorescence. ( ) transmission.--in transmitted light we have, as stated above, single or double refraction, polarisation, and diaphaneity. to the quality of _refraction_ is due one of the chief charms of certain precious stones. it is not necessary to explain here what refraction is, for everyone will be familiar with the refractive property of a light-beam when passing through a medium denser than atmospheric air. it will be quite sufficient to say that all the rays are not equal in refractive power in all substances, so that the middle of the spectrum is generally selected as the mean for indexing purposes. it will be seen that the stones in the st, or cubic system, show single refraction, whereas those of all other systems show double refraction; thus, light, in passing through their substance, is deviated, part of it going one way, the other portion going in another direction--that is, at a slightly different angle--so that this property alone will isolate readily all gems belonging to the st system. a well-known simple experiment in physics shows this clearly. a mark on a card or paper is viewed through a piece of double-refracting spar (iceland spar or clear calcite), when the mark is doubled and two appear. on rotating this rhomb of spar, one of these marks is seen to revolve round the other, which remains stationary, the moving mark passing further from the centre in places. when the spar is cut and used in a certain direction, we see but one mark, and such a position is called its optical axis. _polarisation_ is when certain crystals possessing double refraction have the power of changing light, giving it the appearance of poles which have different properties, and the polariscope is an instrument in which are placed pieces of double-refracting (iceland) spar, so that all light passing through will be polarised. since only crystals possessing the property of double refraction show polarisation, it follows that those of the st, or cubic system--in which the diamond stands a prominent example--fail to become polarised, so that when such a stone is placed in the polariscope and rotated, it fails _at every point_ to transmit light, which a double-refracting gem allows to pass except when its optical axis is placed in the axis of the polariscope, but this will be dealt with more fully when the methods of testing the stones come to be considered. _diaphaneity_, or the power of transmitting light:--some rather fine trade distinctions are drawn between the stones in this class, technical distinctions made specially for purposes of classification, thus:--a "non-diaphanous" stone is one which is quite opaque, no light of any kind passing through its substance; a "diaphanous" stone is one which is altogether transparent; "semi-diaphanous" means one not altogether transparent, and sometimes called "sub-transparent." a "translucent" stone is one in which, though light passes through its substance, sight is not possible through it; whilst in a "sub-translucent" stone, light passes through it, but only in a small degree. the second physical property of light is seen in those stones which owe their beauty or value to reflection: this again may be dependent on lustre, or colour. ~lustre.~--this is an important characteristic due to reflection, and of which there are six varieties:--([alpha]) adamantine (which some authorities, experts and merchants subdivide as detailed below); ([beta]) pearly; ([gamma]) silky; ([delta]) resinous; ([epsilon]) vitreous; ([zeta]) metallic. these may be described:-- ([alpha]) adamantine, or the peculiar lustre of the diamond, so called from the lustre of adamantine spar, which is a form of corundum (as is emery) with a diamond-like lustre, the hard powder of which is used in polishing diamonds. it is almost pure anhydrous alumina (al_{ }o_{ }) and is, roughly, four times as heavy as water. the lustre of this is the true "adamantine," or diamond, brilliancy, and the other and impure divisions of this particular lustre are: _splendent_, when objects are reflected perfectly, but of a lower scale of perfection than the true "adamantine" standard, which is absolutely flawless. when still lower, and the reflection, though maybe fairly good, is somewhat "fuzzy," or is confused or out of focus, it is then merely _shining_; when still less distinct, and no trace of actual reflection is possible (by which is meant that no object can be reproduced in any way to define it, as it could be defined in the reflection from still water or the surface of a mirror, even though imperfectly) the stone is then said to _glint_ or _glisten_. when too low in the scale even to glisten, merely showing a feeble lustre now and again as the light is reflected from its surface in points which vary with the angle of light, the stone is then said to be _glimmering_. below this, the definitions of lustre do not go, as such stones are said to be _lustreless_. ([beta]) pearly, as its name implies, is the lustre of a pearl. ([gamma]) silky, possessing the sheen of silk, hence its name. ([delta]) resinous, also explanatory in its name; amber and the like come in this variety. ([epsilon]) vitreous. this also explains itself, being of the lustre of glass, quartz, etc.; some experts subdividing this for greater defining accuracy into the "sub-vitreous" or lower type, for all but perfect specimens. ([zeta]) metallic or sub-metallic. the former when the lustre is perfect as in gold; the latter when the stones possess the less true lustre of copper. ~colour.~--colour is an effect entirely dependent upon light, for in the total absence of light, such as in black darkness, objects are altogether invisible to the normal human eye. in daylight, also, certain objects reflect so few vibrations of light, or none, that they appear grey, black, or jet-black; whilst those which reflect all the rays of which light is composed, and in the same number of vibrations, appear white. between these two extremes of _none_ and _all_ we find a wonderful play and variety of colour, as some gems allow the red rays only to pass and therefore appear red; others allow the blue rays only and these appear blue, and so on, through all the shades, combinations and varieties of the colours of which light is composed, as revealed by the prism. but this is so important a matter that it demands a chapter to itself. the third physical property of light, phosphorescence, is the property possessed by certain gems and minerals of becoming phosphorescent on being rubbed, or on having their temperature raised by this or other means. it is difficult to say exactly whether this is due to the heat, the friction, or to electricity. perhaps two or all of these may be the cause, for electricity is developed in some gems--such as the topaz--by heat, and heat by electricity, and phosphorescence developed by both. for example, if we rub together some pulverised fluorspar in the dark, or raise its temperature by the direct application of heat, such as from a hot or warm iron, or a heated wire, we at once obtain excellent phosphorescence. common quartz, rubbed against a second piece of the same quartz in the dark, becomes highly phosphorescent. certain gems, also, when merely exposed to light--sunlight for preference--then taken into a darkened room, will glow for a short time. the diamond is one of the best examples of this kind of phosphorescence, for if exposed to sunlight for a while, then covered and rapidly taken into black darkness, it will emit a curious phosphorescent glow for from one to ten seconds; the purer the stone, the longer, clearer and brighter the result. chapter vi. physical properties. d--colour. colour is one of the most wonderful effects in nature. it is an attribute of light and is not a part of the object which appears to be coloured; though all objects, by their chemical or physical composition, determine the number and variety of vibrations passed on or returned to the eye, thus fixing their own individual colours. we have also seen that if an _equal_ light-beam becomes obstructed in its passage by some substance which is denser than atmospheric air, it will become altered in its direction by refraction or reflection, and polarised, each side or pole having different properties. polarised light cannot be made again to pass in a certain direction through the crystal which has polarised it; nor can it again be reflected at a particular angle; so that in double-refracting crystals, these two poles, or polarised beams, are different in colour, some stones being opaque to one beam but not to the other, whilst some are opaque to both. this curious phenomenon, with this brief, though somewhat technical explanation, shows the cause of many of the great charms in precious stones, for when viewed at one angle they appear of a definite colour, whilst at another angle they are just as decided in their colour, which is then entirely different; and as these angles change as the eye glances on various facets, the stone assumes a marvellous wealth of the most brilliant and intense colour of kaleidoscopic variety, even in a stone which may itself be absolutely clear or colourless to ordinary light. such an effect is called pleochroism, and crystals which show variations in their colour when viewed from different angles, or by transmitted light, are called pleochroic, or pleochromatic--from two greek words signifying "to colour more." to aid in the examination of this wonderfully beautiful property possessed by precious stones, a little instrument has been invented called the dichroscope, its name showing its greek derivation, and meaning--"to see colour twice" (twice, colour, to see). it is often a part of a polariscope; frequently a part also of the polarising attachment to the microscope, and is so simple and ingenious as to deserve detailed explanation. in a small, brass tube is fixed a double-image prism of calcite or iceland spar, which has been achromatised--that is, clear, devoid of colour--and is therefore capable of transmitting light without showing any prismatic effect, or allowing the least trace of any except the clear light-beam to pass through. at one end of this tube there is a tiny square hole, the opposite end carrying a small convex lens, of such a strength or focus as to show the square hole in true focus, that is, with perfectly sharp definition, even up to the corners of the square. on looking through the tube, the square hole is duplicated, two squares being seen. the colours of a gem are tested by the stone being put in front of this square, when the two colours are seen quite distinctly. not only is this a simple means of judging colour, but it enables a stone to be classified readily. for if the dichroscope shows two images of _the same_ colour, then it may possibly be a carbuncle, or a diamond, as the case may be--for single-refracting stones, of the first or cubic system, show two images of _the same_ colour. but if these two colours are different, then it must be a double-refracting stone, and according to the particular colours seen, so is the stone classified, for each stone has its own identical colour or colours when viewed through this small but useful instrument. how clear and distinct are these changes may be viewed without it in substances strongly dichroic; for instance, if common mica is viewed in one direction, it is transparent as polished plate-glass, whilst at another angle, it is totally opaque. chloride of palladium also is blood-red when viewed parallel to its axis, and transversely, it is a remarkably bright green. the beryl also, is sea-green one way and a beautiful blue another; the yellow chrysoberyl is brown one way and yellow with a greenish cast when viewed another way. the pink topaz shows rose-colour in one direction and yellow in another. these are perhaps the most striking examples, and are mostly self-evident to the naked eye, whilst in other cases, the changes are so delicate that the instrument must be used to give certainty; some again show changes of colour as the stone is revolved in the dichroscope, or the instrument revolved round the stone. some stones, such as the opal, split up the light-beams as does a prism, and show a wonderful exhibition of prismatic colour, which is technically known as a "play of colour." the descriptive term "opalescence" is self-suggesting as to its origin, which is the "noble" or "precious" opal; this radiates brilliant and rapidly changing iridescent reflections of blue, green, yellow and red, all blending with, and coming out of, a curious silky and milky whiteness, which is altogether characteristic. the moonstone is another example of this peculiar feature which is possessed in a more or less degree by all the stones in the class of pellucid jewels, but no stone or gem can in any way even rival the curious mixture of opaqueness, translucency, silkiness, milkiness, fire, and the steadfast changeable and prismatic brilliance of colour of the precious opal. the other six varieties of opal are much inferior in their strange mixture of these anomalies of light and colour. given in order of value, we have as the second, the "fire" opal with a red reflection, and, as a rule, that only. the third in value is the "common" opal, with the colours of green, red, white and yellow, but this is easily distinguishable from the "noble" or "precious" variety in that the common opal does not possess that wonderful "play" of colour. the fourth variety is called the "semi-opal," which is really like the third variety, the "common," but of a poorer quality and more opaque. the fifth variety in order of value, is that known as the "hydrophane," which has an interesting characteristic in becoming transparent when immersed in water, and only then. the sixth is the "hyalite," which has but a glassy or vitreous lustre, and is found almost exclusively in the form of globules, or clusters of globules, somewhat after the form and size of bunches of grapes; hence the name "botryoidal" is often applied to this variety. the last and commonest of all the seven varieties of opal is somewhat after the shape of a kidney (reniform), or other irregular shape, occasionally almost transparent, but more often somewhat translucent, and very often opaque. this seventh class is called "menilite," being really an opaline form of quartz, originally found at menilmontant, hence its name (_menil_, and greek _lithos_, stone). it is a curious blue on the exterior of the stone, brown inside. history records many magnificent and valuable opals, not the least of which was that of nonius, who declined to give it to mark antony, choosing exile rather than part with so rare a jewel, which pliny describes as being existent in his day, and of a value which, in present english computation, would exceed one hundred thousand pounds. many other stones possess one or more properties of the opal, and are therefore considered more or less opalescent. this "play of colour" and "opalescence," must not be confused with "change of colour." the two first appear mostly in spots and in brilliant points or flashes of coloured light, or "fire" as it is termed. this fire is constantly on the move, or "playing," whereas "change of colour," though not greatly dissimilar, is when the fire merely travels over broader surfaces, each colour remaining constant, such as when directly moving the stone, or turning it, when the broad mass of coloured light slowly changes, usually to its complementary. thus in this class of stone, subject to "change of colour," a green light is usually followed by its complementary, red, yellow by purple, blue by orange, green by brown, orange by grey, purple by broken green, with all the intermediary shades of each. thus when the line of sight is altered, or the stone moved, never otherwise, the colours chase one another over the surface of the gem, and mostly in broad splashes; but in those gems possessing "play of colour," strictly speaking, whilst the stone itself remains perfectly still, and the sight is fixed unwaveringly upon it, the pulsations of the blood in the eyes, with the natural movements of the eyes and eyelids, even in a fixed, steady glance, are quite sufficient to create in the stone a display of sparks and splashes of beautiful fiery light and colour at every tremor. the term "iridescence" is used when the display of colour is seen on the surface, rather than coming out of the stone itself. the cause of this is a natural, or in some cases an accidental, breaking of the surface of the stone into numerous cobweb-like cracks; these are often of microscopic fineness, only perceptible under moderately high powers. nevertheless they are quite sufficient to interfere with and refract the light rays and to split them up prismatically. in some inferior stones this same effect is caused or obtained by the application of a gentle heat, immersion in chemicals, subjection to "x rays" and other strong electric influence, and in many other ways. as a result, the stone is very slightly expanded, and as the molecules separate, there appear on the surface thousands, perhaps millions, of microscopic fissures running at all angles, so that no matter from what position the stone may be viewed, a great number of these fissures are certain to split up the light into prismatic colours causing brilliant iridescence. similar fissures may often be seen with the naked eye on glass, especially if scorched or cooled too rapidly (chilled), and on the surface of clear spar and mica, their effects being of extreme interest, from a colour point of view, at least. chapter vii. physical properties. e--hardness. hardness is perhaps one of the most important features in a stone, especially those of the "gem" series, for no matter how colour, lustre, general beauty and even rarity may entitle a stone to the designation "precious," unless it possesses great hardness it cannot be used as a gem or jewel. consequently, the hardness of jewels is a matter of no small importance, and by dint of indefatigable research, in tests and comparison, all known precious stones have been classified in various scales or degrees of hardness. the most popular and reliable table is that of mohs, in which he takes talc as the softest of the rarer minerals and classes this as no. ; from that he goes by gradual steps to the diamond, the hardest of the stones, which he calls no. , and between these two all other gems are placed. here is given a complete list of mohs's arrangement of stones, according to their hardness, beginning at no. , thus:-- talc rock salt amber - / calcite malachite - / jet - / fluorspar apatite dioptase kyanite (various) - haüynite - / hæmatite - / lapis lazuli - / moldavite (various) - / - - / rhodonite - / - - / obsidian - / sphene - / opal (various) - / - - / nephrite - / chrysolite - felspar adularia amazon stone diopside iron pyrites labradorite turquoise spodumene - / - the chalcedony group which embraces the agate, carnelian, etc. - / demantoid - / epidote - / idocrase - / garnets (see also "red garnets" below) - / - - / axinite - / jadeite - / quartz, including rock-crystal, amethyst, jasper, chrysoprase citrine, etc. jade dichorite (water sapphire) - - / cordierite - / red garnets (see also garnets above) - / tourmaline - / andalusite - / euclase - / staurolite - / zircon - / emerald, aquamarine, or beryl - / phenakite - / spinel topaz chrysoberyl - / the corundum group embracing the ruby, sapphire, etc. diamond (see also list of stones, arranged in their respective colours, in chapter xii.) the method of testing is very simple. a representative selection of the above stones, each with a sharp edge, is kept for the purpose of scratching and being scratched, and those usually set apart for tests in the various groups, are as follows:-- talc rock-salt, or gypsum calcite fluorspar apatite felspar quartz topaz corundum diamond the stone under examination may perhaps first be somewhat roughly classified by its colour, cleavage, and general shape. one of these standard stones is then gently rubbed across its surface and then others of increasingly higher degrees, till no scratch is evident under a magnifying glass. thus if quartz ceases to scratch it, but a topaz will do so, the degree of hardness must lie between and . then we reverse the process: the stone is passed over the standard, and if both quartz and topaz are scratched, then the stone is at least equal in hardness to the topaz, and its classification becomes an easy matter. instead of stones, some experts use variously-tempered needles of different qualities and compositions of iron and steel. for instance, a finely-tempered ordinary steel needle will cut up to no. stones; one made of tool steel, up to ; one of manganese steel, to - / ; one made of high-speed tool steel, to and - / , and so on, according to temper; so that from the scratch which can be made with the finger-nail on mica, to the hardness of the diamond, which diamond alone will scratch readily, the stones may be picked out, classified and tested, with unerring accuracy. it will thus be seen how impossible it is, even in this one of many tests, for an expert to be deceived in the purchase of precious stones, except through gross carelessness--a fault seldom, if ever, met with in the trade. for example--a piece of rock-crystal, chemically coloured, and cut to represent a ruby, might appear so like one as to deceive a novice, but the mere application to its surface of a real ruby, which is hardness , or a no. needle, would reveal too deep or powdery a scratch; also its possibility of being scratched by a topaz or a no. needle, would alone prove it false, for the corundum group, being harder than no. , could not be scratched by it. so would the expert go down the scale, the tiny scratches becoming fainter as he descended, because he would be approaching more nearly the hardness of the stone under test, till he arrived at the felspar, no. , which would be too soft to scratch it, yet the stone would scratch the felspar, but not zircon or andalusite, - / , or topaz, , so that his tests would at once classify the stone as a piece of cut and coloured quartz, thus confirming what he would, at the first sight, have suspected it to be. the standard stones themselves are much more certain in results than the needles, which latter, though well selected and tempered, are not altogether reliable, especially in the more delicate distinctions of picking out the hardest of certain stones of the same kind, in which cases only the expert judge can decide with exactness. accurate in this the expert always is, for he judges by the sound and depth of his cut, and by the amount and quality of the powder, often calling the microscope to his aid, so that when the decision is made finally, there is never the least doubt about it. rapidly as these tests can be made, they are extremely reliable, and should the stone be of great value, it is also subjected to other unerring tests of extreme severity, any one of which would prove it false, if it chanced to be so, though some stones are manufactured and coloured so cleverly that to all but the expert judge and experienced dealer, they would pass well for the genuine. in mohs's list it will be seen that several stones vary considerably, the opal, for instance, having a degree of hardness from - / to - / inclusive. all stones differ slightly, though almost all may be said to fit their position in the scale; but in the case of the opal, the difference shown is partly due to the many varieties of the stone, as described in the last chapter. in applying this test of hardness to a cut gem, it will be noticed that some parts of the same stone seem to scratch more readily than others, such as on a facet at the side, which is often softer than those nearest the widest part of the stone, where the claws, which hold it in its setting, usually come. this portion is called the "girdle," and it is on these "girdle" facets that the scratches are generally made. this variation in hardness is mostly caused by cleavage, these cleavage planes showing a marked, though often but slight, difference in the scratch, which difference is _felt_ rather than seen. in addition to the peculiar _feel_ of a cutting scratch, is the _sound_ of it. on a soft stone being cut by a hard one, little or no sound is heard, but there will form a plentiful supply of powder, which, on being brushed off, reveals a more or less deep incision. but as the stones approach one another in hardness, there will be little powder and a considerable increase in the noise; for the harder are the stones, cutting and being cut, the louder will be the sound and the less the powder. an example of this difference is evident in the cutting of ordinary glass with a "set" or "glazier's" diamond, and with a nail. if the diamond is held properly, there will be heard a curious sound like a keen, drawn-out "kiss," the diamond being considerably harder than the material it cut. an altogether different sound is that produced by the scratching of glass with a nail. in this case, the relative difference in hardness between the two is small, so that the glass can only be scratched and not "cut" by the nail; it is too hard for that, so the noise is much greater and becomes a screech. experience, therefore, makes it possible to tell to a trifle, at the first contact, of what the stone is composed, and in which class it should be placed, by the mere "feel" of the scratch, the depth of it, the amount and kind of powder it leaves, and above all, by the sound made, which, even in the tiniest scratch, is quite characteristic. chapter viii. physical properties. f--specific gravity. the fixing of the specific gravity of a stone also determines its group position with regard to weight; its colour and other characteristics defining the actual stone. this is a safe and very common method of proving a stone, since its specific gravity does not vary more than a point or so in different specimens of the same stone. there are several ways of arriving at this, such as by weighing in balances in the usual manner, by displacement, and by immersion in liquids the specific gravity of which are known. cork is of less specific gravity than water, therefore it floats on the surface of that liquid, whereas iron, being heavier, sinks. so that by changing the liquid to one lighter than cork, the cork will sink in it as does iron in water; in the second instance, if we change the liquid to one heavier than iron, the iron will float on it as does cork on water, and exactly as an ordinary flat-iron will float on quicksilver, bobbing up and down like a cork in a tumbler of water. if, therefore, solutions of known but varying densities are compounded, it is possible to tell almost to exactitude the specific gravity of any stone dropped into them, by the position they assume. thus, if we take a solution of pure methylene iodide, which has a specific gravity of . , and into this drop a few stones selected indiscriminately, the effect will be curious: first, some will sink plump to the bottom like lead; second, some will fall so far quickly, then remain for a considerable time fairly stationary; third, some will sink very slowly; fourth, some will be partially immersed, that is, a portion of their substance being above the surface of the liquid and a portion covered by it; fifth, some will float on the surface without any apparent immersion. in the first case, the stones will be much heavier than . ; in the second, the stones will be about . ; in the third and fourth instances, the stones will be about the same specific gravity as the liquid, whilst in the fifth, they will be much lighter, and thus a rough but tolerably accurate isolation may be made. on certain stones being extracted and placed in other liquids of lighter or denser specific gravity, as the case may be, their proper classification may easily be arrived at, and if the results are checked by actual weight, in a specific gravity balance, they will be found to be fairly accurate. the solution commonly used for the heaviest stones is a mixture of nitrate of thallium and nitrate of silver. this double nitrate has a specific gravity of . , therefore such a stone as zircon, which is the heaviest known, will float in it. for use, the mixture should be slightly warmed till it runs thin and clear; this is necessary, because at ° (taking this as ordinary atmospheric temperature) it is a stiff mass. a lighter liquid is a mixture of iodide of mercury in iodide of potassium, but this is such an extremely corrosive and dangerous mixture, that the more common solution is one in which methylene iodide is saturated with a mixture of iodoform until it shows a specific gravity of . ; and by using the methylene iodide alone, in its pure state, it having a specific gravity of . , the stones to that weight can be isolated, and by diluting this with benzole, its weight can be brought down to that of the benzole itself, as in the case of sonstadt's solution. this solution, in full standard strength, has a specific gravity of . , but may be weakened by the addition of distilled water in varying proportions till the weight becomes almost that of water. knowing the specific gravity of all stones, and dividing them into six groups, by taking a series of standard solutions selected from one or other of the above, and of known specific gravity, we can judge with accuracy if any stone is what it is supposed to be, and classify it correctly by its mere floating or sinking when placed in these liquids. beginning then with the pure double nitrate of silver and thallium, this will isolate the stones of less specific gravity than . , and taking the lighter solutions and standardising them, we may get seven solutions which will isolate the stones as follows:-- a {shows the stones which have} . {a specific gravity over} b " " " . and under . c " " " . " . d " " " . " . e " " " . " . f " " " . " . g " " -- -- under . therefore each liquid will isolate the stones in its own group by compelling them to float on its surface; commencing with the heaviest and giving to the groups the same letters as the liquids, it is seen that-- _group_ a.--isolates gems with a specific gravity of . and over . ; in this group is placed zircon, with a specific gravity of from . to . . _group_ b.--stones whose specific gravity lies between . and under . . garnets, many varieties. see group d below. almandine . and occasionally to . ruby . " . sapphire . " . corundum . " . cape ruby . demantoid . staurolite . malachite . and occasionally to . _group_ c.--stones whose specific gravity lies between . and under . . pyrope (average) . chrysoberyl . and occasionally to . spinel . " . kyanite . " . hessonite . " . diamond . " . topaz . " . _group_ d.--stones whose specific gravity lies between and under . . rhodonite . and occasionally to . garnets . " . epidote . " . sphene . and occasionally to . idocrase . " . olivine . " . chrysolite . " . jade . " . jadeite . axinite . dioptase . diopside . tourmaline (yellow) . andalusite . apatite . tourmaline (blue and violet) . tourmaline (green) . " (red) . spodumene . and occasionally to . euclase . fluorspar . and occasionally to . tourmaline (colourless) . tourmaline (blush rose) . tourmaline (black) . and occasionally to . nephrite . _group_ e.--stones whose specific gravity lies between . and under . . phenakite . turquoise . beryl . and occasionally to . aquamarine . " . labradorite . emerald . quartz . chrysoprase . jasper . amethyst . hornstone . citrine . cordierite . agate . chalcedony . and occasionally to . adularia . rock-crystal . and occasionally to . _group_ f.--stones whose specific gravity lies between . and under . . haüynite . and occasionally to . lapis lazuli . moldavite . opal . and according to variety to . " (fire opal) . (average) _group_ g.--stones whose specific gravity is under . . jet . amber . (see also list of stones, arranged in their respective colours, in chapter xii.) in many of these cases the specific gravity varies from . to . , but the above are the average figures obtained from a number of samples specially and separately weighed. in some instances this difference may cause a slight overlapping of the groups, as in group c, where the chrysoberyl may weigh from . to . , thus bringing the heavier varieties of the stone into group b, but in all cases where overlapping occurs, the colour, form, and the self-evident character of the stone are in themselves sufficient for classification, the specific gravity proving genuineness. this is especially appreciated when it is remembered that so far science has been unable (except in very rare instances of no importance) to manufacture any stone of the same colour as the genuine and at the same time of the same specific gravity. either the colour and characteristics suffer in obtaining the required weight or density, or if the colour and other properties of an artificial stone are made closely to resemble the real, then the specific gravity is so greatly different, either more or less, as at once to stamp the jewel as false. in the very few exceptions where chemically-made gems even approach the real in hardness, colour, specific gravity, &c., they cost so much to obtain and the difficulties of production are so great that they become mere chemical curiosities, far more costly than the real gems. further, they are so much subject to chemical action, and are so susceptible to their surroundings, that their purity and stability cannot be maintained for long even if kept airtight; consequently these ultra-perfect "imitations" are of no commercial value whatever as jewels, even though they may successfully withstand two or three tests. chapter ix. physical properties. g--heat. another method of isolating certain stones is by the action of heat-rays. remembering our lessons in physics we recall that just as light-rays may be refracted, absorbed, or reflected, according to the media through which they are caused to pass, so do heat-rays possess similar properties. therefore, if heat-rays are projected through precious stones, or brought to bear on them in some other manner than by simple projection, they will be refracted, absorbed, or reflected by the stones in the same manner as if they were light-rays, and just as certain stones allow light to pass through their substance, whilst others are opaque, so do some stones offer no resistance to the passage of heat-rays, but allow them free movement through the substance, whilst, in other cases, no passage of heat is possible, the stones being as opaque to heat as to light. indeed, the properties of light and heat are in many ways identical, though the test by heat must in all cases give place to that by light, which latter is by far of the greater importance in the judging and isolation of precious stones. it will readily be understood that in the spectrum the outer or extreme light-rays at each side are more or less bent or diverted, but those nearest the centre are comparatively straight, so that, as before remarked, these central rays are taken as being the standard of light-value. this divergence or refraction is greater in some stones than in others, and to it the diamond, as an example, owes its chief charm. in just such manner do certain stones refract, absorb, or reflect heat; thus amber, gypsum, and the like, are practically opaque to heat-rays, in contrast with those of the nature of fluorspar, rock-salt, &c., which are receptive. heat passes through these as easily as does light through a diamond, such stones being classed as diathermal (to heat through). so that all diathermal stones are easily permeable by radiant heat, which passes through them exactly as does light through transparent bodies. others, again, are both single and double refracting to heat-rays, and it is interesting to note the heat-penetrating value as compared with the refractive indexes of the stone. in the following table will be found the refractive indexes of a selection of single and double refractive stones, the figures for "light" being taken from a standard list. the second column shows the refractive power of heat, applied to the actual stones, and consisting of a fine pencil blowpipe-flame, one line (the one twelfth part of an inch) in length in each case. this list must be taken as approximate, since in many instances the test has been made on one stone only, without possibility of obtaining an average; and as stones vary considerably, the figures may be raised or lowered slightly, or perhaps even changed in class, because in some stones the least stain or impurity may cause the heat effects to be altered greatly in their character, and even to become singly or doubly refracting, opaque or transparent, to heat-rays, according to the nature of the impurity or to some slight change in the crystalline structure, and so on. _selection of singly refracting stones._ _indexes of rays of_ light. heat. fluorspar . . varies opal . . " spinel . . almandine . . diamond . . double _selection of doubly refracting stones._ _indexes of rays of_ light. heat. quartz . . single and double beryl . . varies considerably topaz . . " " chrysoberyl . . " " ruby . . single and double the tourmaline has a light-refractive index of . , with a heat index of none, being to heat-rays completely opaque. the refractive index of gypsum is . , but heat none, being opaque. the refractive index of amber is . , but heat none, being opaque. in some of the specimens the gypsum showed a heat-penetration index of . , and amber of . , but mostly not within the third point. in all cases the heat-penetration and refraction were shown by electric recorders. these figures are the average of those obtained from tests made in some cases on several stones of the same kind, and also on isolated specimens. not only does the power of the stone to conduct heat vary in different stones of the same kind or variety, as already explained, but there is seen a remarkable difference in value, according to the spot on which the heat is applied, so that on one stone there is often seen a conductivity varying between . to . . this is owing to the differences of expansion due to the temporary disturbance of its crystalline structure, brought about by the applied heat. this will be evident when heat is applied on the axes of the crystal, on their faces, angles, lines of symmetry, etc., etc., each one of which gives different results, not only as to value in conductivity, but a result which varies in a curious degree, out of all proportion to the heat applied. in many cases a slight diminution in applied heat gives a greater conductivity, whilst in others a slight rise in the temperature of the heat destroys its conductivity altogether, and renders the stone quite opaque to heat-rays. this anomaly is due entirely to the alteration of crystalline structure, which, in the one case, is so changed by the diminution in heat as to cause the crystals to be so placed that they become diathermal, or transparent to heat-rays; whilst, in the other instance, the crystals which so arrange themselves as to be diathermal are, by a slightly increased temperature, somewhat displaced, and reflect, or otherwise oppose the direct passage of heat-rays, which, at the lower temperature, obtained free passage. thus certain stones become both opaque and diathermal, and as the heat is caused to vary, so do they show the complete gamut between the two extremes of total opacity and complete transparency to heat-rays. for the purpose under consideration, the temperature of the pencil of heat applied to the stones in their several portions was kept constant. it will be seen, therefore, that no great reliance can be placed on the heat test as applied to precious stones. chapter x. physical properties. h--magnetic and electric influences. the word "electricity" is derived from the greek "elektron," which was the name for amber, a mineralised resin of extinct pine-trees. it was well-known to the people of pre-historic times; later to the early egyptians, and, at a still later date, we have recorded how thales--the greek philosopher, who lived about the close of the th century b.c., and was one of the "seven wise men"--discovered the peculiar property which we call "electricity" by rubbing dry silk on amber. many stones are capable of exhibiting the same phenomenon, not only by friction, as in thales's experiment, but also under the influence of light, heat, magnetism, chemical action, pressure, etc., and of holding or retaining this induced or added power for a long or short period, according to conditions and environment. if a small pith ball is suspended from a non-conducting support, it forms a simple and ready means of testing the electricity in a stone. according to whether the ball is repelled or attracted, so is the electricity in the stone made evident, though the electroscope gives the better results. by either of these methods it will be found that some of the stones are more capable of giving and receiving charges of electricity than are others; also that some are charged throughout with one kind only, either positive or negative, whilst others have both, becoming polarised electrically, having one portion of their substance negative, the other positive. for instance, amber, as is well known, produces negative electricity under the influence of friction, but in almost all cut stones, other than amber, the electricity produced by the same means is positive, whereas in the _uncut_ stones the electricity is negative, with the exception of the diamond, in which the electricity is positive. when heated, some stones lose their electricity; others develop it, others have it reversed, the positive becoming negative and vice versâ; others again, when heated, become powerfully magnetic and assume strong polarity. when electricity develops under the influence of heat, or is in any way connected with a rising or falling of temperature in a body, it is called "pyro-electricity," from the greek word "pyros," fire. the phenomenon was first discovered in the tourmaline, and it is observed, speaking broadly, only in those minerals which are hemimorphic, that is, where the crystals have different planes or faces at their two ends, examples of which are seen in such crystals as those of axinite, boracite, smithsonite, topaz, etc., all of which are hemimorphic. taking the tourmaline as an example of the pyro-electric minerals, we find that when this is heated to between ° f. and ° f. it assumes electric polarity, becoming electrified positively at one end or pole and negatively at the opposite pole. if it is suspended on a silken thread from a glass rod or other non-conducting support in a similar manner to the pith ball, the tourmaline will be found to have become an excellent magnet. by testing this continually as it cools there will soon be perceived a point which is of extreme delicacy of temperature, where the magnetic properties are almost in abeyance. but as the tourmaline cools yet further, though but a fraction of a degree, the magnetic properties change; the positive pole becomes the negative, the negative having changed to the positive. it is also interesting to note that if the tourmaline is not warmed so high as to reach a temperature of ° f., or is heated so strongly as to exceed more than a few degrees above ° f., then these magnetic properties do not appear, as no polarity is present. this polarity, or the presence of positive and negative electricity in one stone, may be strikingly illustrated in a very simple manner:--if a little sulphur and red-lead, both in fine powder, are shaken up together in a paper or similar bag, the moderate friction of particle against particle electrifies both; one negatively, the other positively. if, then, a little of this now golden-coloured mixture is gently dusted over the surface of the tourmaline or other stone possessing electric polarity, a most interesting change is at once apparent. the red-lead separates itself from the sulphur and adheres to the negative portion of the stone, whilst the separated sulphur is at once attracted to the positive end, so that the golden-coloured mixture becomes slowly transformed into its two separate components--the brilliant yellow sulphur, and the equally brilliant red-lead. these particles form in lines and waves around the respective poles in beautiful symmetry, their positions corresponding with the directions of the lines of magnetic force, exactly as will iron filings round the two poles of a magnet. from this it will clearly be seen how simple a matter it is to isolate the topaz, tourmaline, and all the pyro-electric stones from the non-pyro-electric, for science has not as yet been able to give to spurious stones these same electric properties, however excellent some imitations may be in other respects. further, almost all minerals lose their electricity rapidly on exposure to atmospheric influences, even to dry air; the diamond retains it somewhat longer than most stones, though the sapphire, topaz, and a few others retain it almost as long again as the diamond, and these electric properties are some of the tests which are used in the examination of precious stones. those stones which show electricity on the application of pressure are such as the fluorspar, calcite, and topaz. with regard to magnetism, the actual cause of this is not yet known with certainty. it is, of course, a self-evident fact that the magnetic iron ore, which is a form of peroxide, commonly known as magnetite, or lodestone, has the power of attracting a magnet when swinging free, or of being attracted by a magnet, to account for which many plausible reasons have been advanced. perhaps the most reasonable and acceptable of these is that this material contains molecules which have half their substance positively and the other half negatively magnetised. substances so composed, of which magnets are an example, may be made the means of magnetising other substances by friction, without they themselves suffering any loss; but it is not all substances that will respond to the magnet. for instance, common iron pyrites, fes_{ }, is unresponsive, whilst the magnetic pyrites, which varies from fes, fe_{ }s_{ }, to fes, fe_{ }s_{ }, and is a sulphide of iron, is responsive both positively and negatively. bismuth and antimony also are inactive, whilst almost all minerals containing even a small percentage of iron will deflect the magnetic needle, at least under the influence of heat. so that from the lodestone--the most powerfully magnetic mineral known--to those minerals possessing no magnetic action whatever, we have a long, graduated scale, in which many of the precious stones appear, those containing iron in their composition being more or less responsive, as already mentioned, and that either in their normal state, or when heated, and always to an extent depending on the quantity or percentage of iron they contain. in this case, also, science has not as yet been able to introduce into an artificial stone the requisite quantity of iron to bring it the same analytically as the gem it is supposed to represent, without completely spoiling the colour. so that the behaviour of a stone in the presence of a magnet, to the degree to which it should or should not respond, is one of the important tests of a genuine stone. chapter xi. the cutting of precious stones. as existing in a state of nature precious stones do not, as a rule, exhibit any of those beautiful and wonderful properties which cause them to be so admired and sought after as to become of great intrinsic value, for their surfaces have become clouded by innumerable fine cuts or abrasions, because of the thousands of years during which they have been under pressure, or tumbled about in rivers, or subjected to the incessant friction caused by surrounding substances. all this occurring above and under ground has given them an appearance altogether different to that which follows cutting and polishing. further, the shape of the stone becomes altered by the same means, and just as michael angelo's figure was already in the marble, as he facetiously said, and all he had to do was to chip off what he did not require till he came to it, so is the same process of cutting and polishing necessary to give to the precious stones their full value, and it is the manner in which these delicate and difficult operations are performed that is now under consideration. just as experience and skill are essential to the obtaining of a perfect figure from the block of marble, so must the cutting and polishing of a precious stone call for the greatest dexterity of which a workman is capable, experience and skill so great as to be found only in the expert, for in stones of great value even a slight mistake in the shaping and cutting would probably not only be wasteful of the precious material, but would utterly spoil its beauty, causing incalculable loss, and destroying altogether the refrangibility, lustre and colour of the stone, thus rendering it liable to easy fracture: in every sense converting what would have been a rare and magnificent jewel to a comparatively valueless specimen. one of the chief services rendered by precious stones is that they may be employed as objects of adornment, therefore, the stone must be cut of such a shape as will allow of its being set without falling out of its fastening--not too shallow or thin, to make it unserviceable and liable to fracture, and in the case of a transparent stone, not too deep for the light to penetrate, or much colour and beauty will be lost. again, very few stones are flawless, and the position in which the flaw or flaws appear will, to a great extent, regulate the shape of the stones, for there are some positions in which a slight flaw would be of small detriment, because they would take little or no reflection, whilst in others, where the reflections go back and forth from facet to facet throughout the stone, a flaw would be magnified times without number, and the value of the stone greatly reduced. it is therefore essential that a flaw should be removed whenever possible, but, when this is not practicable, the expert will cut the stone into such a shape as will bring the defect into the least important part of the finished gem, or probably sacrifice the size and weight of the original stone by cutting it in two or more pieces of such a shape that the cutting and polishing will obliterate the defective portions. such a method was adopted with the great cullinan diamond, as described in chapter iv. from this remarkable diamond a great number of magnificent stones were obtained, the two chief being the largest and heaviest at present known. some idea of the size of the original stone may be gathered from the fact that the traditional indian diamond, the "great mogul," is said to have weighed carats. this stone, however, is lost, and some experts believe that it was divided, part of it forming the present famous koh-i-nûr; at any rate, all trace of the great mogul ceased with the looting of delhi in . the koh-i-nûr weighs a little over carats; before cutting it weighed a shade over ; the cullinan, in the same state, weighed nearly carats. this massive diamond was cut into about stones, the largest, now placed in "the royal sceptre with the cross," weighing - / carats, the second, now placed under the historic ruby in "the imperial state crown," weighing - / ths carats. these two diamonds are now called "the stars of africa." both these stones, but especially the larger, completely overshadow the notorious koh-i-nûr, and notwithstanding the flaw which appeared in the original stone, every one of the resulting pieces, irrespective of weight, is without the slightest blemish and of the finest colour ever known, for the great south african diamond is of a quality never even approached by any existing stone, being ideally perfect. it requires a somewhat elaborate explanation to make clear the various styles of cut without illustrations. they are usually divided into two groups, with curved, and with flat or plane surfaces. of the first, the curved surfaces, opaque and translucent stones, such as the moonstone, cat's-eye, etc., are mostly cut _en cabochon_, that is, dome-shaped or semi-circular at the top, flat on the underside, and when the garnet is so cut it is called a carbuncle. in strongly coloured stones, while the upper surface is semi-circular like the cabochon, the under surface is more or less deeply concave, sometimes following the curve of the upper surface, the thickness of the stone being in that case almost parallel throughout. this is called the "hollow" cabochon. other stones are cut so that the upper surface is dome-shaped like the last two, but the lower is more or less convex, though not so deep as to make the stone spherical. this is called the "double" cabochon. a further variety of cutting is known as the _goutte de suif_, or the "tallow-drop," which takes the form of a somewhat flattened or long-focus double-convex lens. the more complicated varieties of cut are those appearing in the second group, or those with plane surfaces. a very old form is the "rose" or "rosette"; in this the extreme upper centre, called the "crown," or "star," is usually composed of six triangles, the apexes of which are elevated and joined together, forming one point in the centre. from their bases descend a further series of triangles, the bases and apexes of which are formed by the bases and lower angles of the upper series. this lower belt is called the "teeth," under which the surface or base of the stone is usually flat, but sometimes partakes of a similar shape to the upper surface, though somewhat modified in form. another variety is called the "table cut," and is used for coloured stones. it has a flat top or "table" of a square or other shape, the edges of which slope outwards and form the "bezils" or that extended portion by which the stone is held in its setting. it will thus be seen that the outside of the stone is of the same shape as that of the "table," but larger, so that from every portion of the "table" the surface extends downwards, sloping outwards to the extreme size of the stone, the underside sloping downwards and inwards to a small and flat base, the whole, in section, being not unlike the section of a "pegtop." a modification of this is known as the "step" cut, sometimes also called the "trap." briefly, the difference between this and the last is that whereas the table has usually one bevel on the upper and lower surfaces, the trap has one or more steps in the sloping parts, hence its name. the most common of all, and usually applied only to the diamond, is the "brilliant" cut. this is somewhat complicated, and requires detailed description. in section, the shape is substantially that of a pegtop with a flat "table" top and a small flat base. the widest portion is that on which the claws, or other form of setting, hold it securely in position. this portion is called the "girdle," and if we take this as a defining line, that portion which appears above the setting of this girdle, is called the "crown"; the portion below the girdle is called the "culasse," or less commonly the "pavilion." commencing with the girdle upwards, we have eight "cross facets" in four pairs, a pair on each side; each pair having their apexes together, meeting on the four extremities of two lines drawn laterally at right angles through the stone. it will, therefore, be seen that one side of each triangle coincides with the girdle, and as their bases do not meet, these spaces are occupied by eight small triangles, called "skill facets," each of which has, as its base, the girdle, and the outer of its sides coincides with the base of the adjoining "cross facet." the two inner sides of each pair of skill facets form the half of a diamond or lozenge-shaped facet, called a "quoin," of which there are four. the inner or upper half of each of these four quoins forms the bases of two triangles, one at each side, making eight in all, which are called "star facets," and the inner lines of these eight star facets form the boundary of the top of the stone, called the "table." the inner lines also of the star facets immediately below the table and those of the cross facets immediately above the girdle form four "templets," or "bezils." we thus have above the girdle, thirty-three facets: cross, skill, quoin, star, table, and templets. reversing the stone and again commencing at the girdle, we have eight "skill facets," sometimes called the lower skill facets, the bases of which are on the girdle, their outer sides forming the bases of eight cross facets, the apexes of which meet on the extremities of the horizontal line, as in those above the girdle. if the basal lines of these cross facets, where they join the sides of the skill facets, are extended to the peak, or narrow end of the stone, these lines, together with the sides of the cross facets, will form four five-sided facets, called the "pavilions"; the spaces between these four pavilions have their ends nearest the girdle formed by the inner sides of the skill facets, and of these spaces, there will, of course, be four, which also are five-sided figures, and are called "quoins," so that there are eight five-sided facets--four large and four narrow--their bases forming a square, with a small portion of each corner cut away; the bases of the broader pavilions form the four sides, whilst the bases of the four narrower quoins cut off the corners of the square, and this flat portion, bounded by the eight bases, is called the "culet," but more commonly "collet." so that below the girdle, we find twenty-five facets: cross, skill, pavilion, quoin, and collet. these, with the of the crown, make , which is the usual number of facets in a brilliant, though this varies with the character, quality, and size of the diamond. for instance, though this number is considered the best for normal stones, specially large ones often have more, otherwise there is danger of their appearing dull, and it requires a vast amount of skill and experience to decide upon the particular number and size of the facets that will best display the fire and brilliance of a large stone, for it is obvious that if, after months of cutting and polishing, it is found that a greater or smaller number of facets ought to have been allowed, the error cannot be retrieved without considerable loss, and probable ruin to the stone. in the case of the cullinan diamonds, the two largest of which are called the stars of africa, facets were cut in the largest portion, while in the next largest the experts decided to make , and, as already pointed out, these stones are, up to the present time, the most magnificent in fire, beauty and purity ever discovered. the positions and angles of the facets, as well as the number, are of supreme importance, and diamond cutters--even though they have rules regulating these matters, according to the weight and size of the stone--must exercise the greatest care and exactitude, for their decision once made is practically unalterable. chapter xii. imitations, and some of the tests, of precious stones. we now arrive at the point where it is necessary to discuss the manufacture and re-formation of precious stones, and also to consider a few of the tests which may be applied to _all_ stones. these are given here in order to save needless repetition; the tests which are specially applicable to individual stones will more properly be found under the description of the stone referred to, so that the present chapter will be devoted chiefly to generalities. with regard to diamonds, the manufacture of these has not as yet been very successful. as will be seen on reference to chapter ii., on "the origin of precious stones," it is generally admitted that these beautiful and valuable minerals are caused by chemically-charged water and occasionally, though not always, high temperature, but invariably beautified and brought to the condition in which they are obtained by the action of weight and pressure, extending unbroken through perhaps ages of time. in these circumstances, science, though able to give chemical properties and pressure, cannot, of course, maintain these continuously for "ages," therefore the chemist must manufacture the jewels in such manner that he may soon see the results of his labours, and though real diamonds may be made, and with comparative ease, from boron in the amorphous or pure state along with aluminium, fused in a crucible at a high temperature, these diamonds are but microscopic, nor can a number of them be fused, or in any other way converted into a large single stone, so that imitation stones, to be of any service must be made of a good clear glass. the glass for this purpose is usually composed of . per cent. of red lead, . per cent. of pure quartz in fine powder, preferably water-ground, and . per cent. of carbonate of potash, the whole coloured when necessary with metallic oxides of a similar nature to the constituents of the natural stones imitated. but for colourless diamonds, the glass requires no such addition to tint it. from the formula given is made the material known as "strass," or "paste," and stones made of it are mostly exhibited under and amongst brilliant artificial lights. the mere fact that they are sold cheaply is _primâ facie_ proof that the stones are glass, for it is evident that a diamond, the commercial value of which might be £ or more, cannot be purchased for a few shillings and be genuine. so long as this is understood and the stone is sold for the few shillings, no harm is done; but to offer it as a genuine stone and at the price of a genuine stone, would amount to fraud, and be punishable accordingly. some of these "paste," or "white stones," as they are called in the trade, are cut and polished exactly like a diamond, and with such success as occasionally to deceive all but experts. such imitations are costly, though, of course, not approaching the value of the real stones; it being no uncommon thing for valuable jewels to be duplicated in paste, whilst the originals are kept in the strong room of a bank or safe-deposit. in all cases, however, a hard file will abrade the surface of the false stone. in chapter vii. we found that quartz is in the seventh degree of hardness, and an ordinary file is but a shade harder than this, so that almost all stones higher than no. are unaffected by a file unless it is used roughly, so as to break a sharp edge. in order to prepare artificial diamonds and other stones for the file and various tests, they are often what is called "converted" into "doublets" or "triplets." these are made as follows: the body of the glass is of paste, and on the "table" (see last chapter), and perhaps on the broader facets, there will be placed a very thin slab of the real stone, attached by cement. in the case of the diamond, the body is clear, but in the coloured imitations the paste portion is made somewhat lighter in shade than the real stone would be, the portion below the girdle being coloured chemically, or mounted in a coloured backing. such a stone will, of course, stand most tests, for the parts usually tested are genuine. a stone of this nature is called a "doublet," and it is evident that when it is tested on the underside, it will prove too soft, therefore the "triplet" has been introduced. this is exactly on the lines of the doublet, except that the collet and perhaps the pavilions are covered also, so that the girdle, which is generally encased by the mounting, is the only surface-portion of paste. in other cases the whole of the crown is genuine, whilst often both the upper and lower portions are solid and genuine, the saving being effected by using a paste centre at the girdle, covered by the mounting. such a stone as this last mentioned is often difficult to detect without using severe tests and desperate means, e.g.:--(a) by its crystalline structure (see chapter iii.); (b) by the cleavage planes (see chapter iv.); (c) by the polariscope (see chapter v.); (d) by the dichroscope (see chapter vi.); (e) by specific gravity (see chapter viii.); (f) cutting off the mounting, and examining the girdle; (g) soaking the stone for a minute or so in a mixture said to have been originally discovered by m. d. rothschild, and composed of hydrofluoric acid and ammonia; this will not answer for all stones, but is safe to use for the diamond and a few others. should the jewel be glass, it will be etched, if not completely destroyed, but if genuine, no change will be apparent; (h) soaking the diamond for a few minutes in warm or cold water, in alcohol, in chloroform, or in all these in turn, when, if a doublet, or triplet, it will tumble to pieces where joined together by the cement, which will have been dissolved. it is, however, seldom necessary to test so far, for an examination under the microscope, even with low power, is usually sufficient to detect in the glass the air-bubbles which are almost inseparable from glass-mixtures, though they do not detract from the physical properties of the glass. the higher powers of the same instrument will almost always define the junction and the layer or layers of cement, no matter how delicate a film may have been used. any one of these tests is sufficient to isolate a false stone. some of the softer genuine stones may be fused together with splinters, dust, and cuttings of the same stones, and of this product is formed a larger stone, which, though manufactured, is essentially perfectly real, possessing exactly the same properties as a naturally formed stone. many such stones are obtained as large as an ordinary pin's head, and are much used commercially for cluster-work in rings, brooches, for watch-jewels, scarf-pins, and the like, and are capable of being cut and polished exactly like an original stone. this is a means of using up to great advantage the lapidary's dust, and though these products are real stones, perhaps a little more enriched in colour chemically, they are much cheaper than a natural stone of the same size and weight. some spurious stones have their colour improved by heat, by being tinged on the outside, by being tinted throughout with a fixed colour and placed in a clear setting; others, again, have a setting of a different hue, so that the reflection of this shall give additional colour and fire to the stone. for instance, glass diamonds are often set with the whole of the portion below the girdle hidden, this part of the stone being silvered like a mirror. others are set open, being held at the girdle only, the portion covered by the setting being silvered. other glass imitations, such as the opal, have a tolerably good representation of the "fiery" opal given to them by the admixture, in the glass, of a little oxide of tin, which makes it somewhat opalescent, and in the setting is placed a backing of red, gold, copper, or fiery-coloured tinsel, whilst the glass itself, at the back, is painted very thinly with a paint composed of well washed and dried fish-scales, reduced to an impalpable powder, mixed with a little pure, refined mastic, or other colourless varnish. this gives a good imitation of phosphorescence, as well as a slight pearliness, whilst the tinsel, seen through the paint and the curious milkiness of the glass, gives good "fire." a knowledge of the colours natural to precious stones and to jewels generally is of great service in their rough classification for testing, even though some stones are found in a variety of colours. an alphabetical list of the most useful is here appended, together with their average specific gravities and hardness. (see also chapter vii. on "hardness," and chapter viii. on "specific gravity.") white or colourless stones. _hardness._ _specific gravity._ (see chapter vii.) (see chapter viii.) beryl - / . - . corundum . - . diamond . - . jade . - . opal - / - - / . - . phenakite - / . quartz . rock-crystal . - . sapphire . - . spinel . - . topaz . - . tourmaline - / . zircon - / . - . yellow stones. _hardness._ _specific gravity._ (see chapter vii.) (see chapter viii.) amber - / . beryl - / . - . chrysoberyl - / . - . chrysolite - . - . corundum (the yellow variety known as "oriental topaz" [not "topaz"], see below) . - . diamond . - . garnets (various) - / - - / . - . hyacinth (a form of zircon) - / . - . quartz (citrine) . sapphire . - . spinel . - . topaz (for "oriental topaz," see above) . - . tourmaline - / . brown and flame-coloured stones. _hardness._ _specific gravity._ (see chapter vii.) (see chapter viii.) andalusite - / . diamond . - . garnets (various) - / - - / . - . hyacinth (a form of zircon), see below - / . - . quartz (smoke coloured) . tourmaline - / . zircon (hyacinth) - / . - . red and rose-coloured stones. _hardness._ _specific gravity._ (see chapter vii.) (see chapter viii.) carnelian (a variety of chalcedony) - / . - . diamond . - . deep red garnet - / . - . jasper . opal (the "fire opal") - / - - / . (average) ruby . - . rhodonite - / - - / . - . sapphire . - . spinel ruby . - . topaz . - . tourmaline - / . zircon - / . - . pink stones. _hardness._ _specific gravity._ (see chapter vii.) (see chapter viii.) beryl - / . - . diamond . - . ruby . - . spinel . - . topaz ("burnt" or "pinked"), see chapter xiv., page . - . tourmaline - / . blue stones. _hardness._ _specific gravity._ (see chapter vii.) (see chapter viii.) beryl - / . - . diamond . - . dichorite (water sapphire) - - / . - . disthene (kyanite) - . - . iolite (cordierite) - / . lapis lazuli - / . sapphire . - . topaz . - . tourmaline - / . turquoise . green stones. _hardness._ _specific gravity._ (see chapter vii.) (see chapter viii.) aquamarine - / . - . chrysoberyl - / . - . chrysolite - . - . chrysoprase (quartz) . diamond . - . dioptase . emerald and oriental emerald - / . euclase - / . garnet (see also red garnet) - / - - / . - . heliotrope (chalcedony) - / . - . hiddenite (a variety of spodumene) - / - . - . jade . - . jadeite . malachite - / . - . peridot (a variety of chrysolite) - . - . plasma (a variety of chalcedony) - / . - . quartz . sapphire . - . topaz . - . tourmaline - / . violet stones. _hardness._ _specific gravity._ (see chapter vii.) (see chapter viii.) amethyst . diamond . - . quartz (amethyst) . sapphire . - . spinel . - . tourmaline - / . chatoyant stones. these stones are easily recognisable by their play of colour. (see chapter xiv.) black stones. _hardness._ _specific gravity._ (see chapter vii.) (see chapter viii.) diamond . - . garnet - / - - / . - . jet - / . onyx (a variety of chalcedony) - / . - . quartz . tourmaline (not unlike black resin in appearance) - / . - . chapter xiii. various precious stones. _the diamond._ to recapitulate certain of the facts respecting the diamond.--this wonderful gem has the distinction amongst precious stones of being unique; though many are composed of two, three, or but a small number of elements, the diamond is the only stone known consisting of one element, and absolutely nothing else--pure crystallised carbon. its hardness is proverbial; not only is it untouched by the action of a hard file, but it occasionally refuses to split when struck with finely tempered steel, which it often causes to break. such was the case with the south african diamond, for when the knife that was to break it was struck smartly with a steel bar, the first blow broke the blade without affecting the diamond, yet a piece of bort, or diamond dust, splinters, or defective diamonds (all these being called bort), may readily be pulverised in a hard steel mortar with a hard steel pestle. the diamond is the hardest stone known; it is also the only stone known which is really combustible. it is of true adamantine lustre, classed by experts as midway between the truly metallic and the purely resinous. in refractive power and dispersion of the coloured rays of light, called its fire, it stands pre-eminent. it possesses a considerable variety of colour; that regarded as the most perfect and rare is the blue-white colour. most commonly, however, the colours are clear, with steely-blue casts, pale and neutral-colour yellow, whilst amongst the most expensive and rare are those of green, pale pink, red, and any other variety with strong and decided colour. although these stones are sold by the carat, there can be no hard and fast rule laid down as to the value of a carat, for this depends on the size, quality, and the purity of the stone. the larger the stone the greater the value per carat, and prices have been known to range from _l._ per carat for a small stone to _l._ per carat for a large one, whereas the exceptionally large stones possess a value almost beyond estimation. it often happens that some stones--particularly those from south africa and brazil--are tinted when uncut, probably by reason of the action upon them of their matrix, especially if ironstone, or with rolling for ages amongst ironstone in river-beds, which gives them a slight metallic appearance; in each case the cause is suggested by the fact that these tinted stones are usually found in such places, and that the tinting is very thin and on the surface only, so that the cutting and shaping of the stone gets below it to the perfectly clear diamond. from pliny and other historians we gather that at various periods considerable superstition has existed with regard to diamonds, such as that if one is powdered it becomes poisonous to a remarkable degree; that gifts of diamonds between lovers--married and unmarried--produce and seal affection; hence the popularity of diamonds in betrothal rings. pretty as is this conceit, there is no doubt about the fact that the gift of diamonds to the object of one's affections does usually produce a feeling of pleasure to both parties, from which it would appear that there is some ground for the belief. _corundum._ this mineral is a species of crystal, or crystalline alumina--an almost pure anhydrous alumina, al_{ }o_{ }--in many varieties, both of shape and colour. the chief stone is the ruby, considered, when large, to be of even more importance and value than the diamond. there are many other red stones in this group; sapphires, also, are a species of corundum, both the blue and the colourless varieties, as are also the aquamarine, the emerald, the amethyst, the topaz, and others, all of widely differing colour, as well as the star-shaped, or "aster" ruby, called the "ruby" cat's-eye. all these vary more in colour than in their chemical properties. still another variety, greyish-black and generally associated with hæmatite iron ore, is called emery, and, when ground in different degrees of fineness, is so well known by its general use as a polishing medium as to need no description. it should, however, be mentioned that amongst the more coarsely ground emery it is no uncommon thing to find minute sapphires, taking sapphires in their broad, commercial meaning, as signifying any variety of corundum, except the red and the emery. the surfaces of crystals of corundum are often clouded or dull, whilst its classification of lustre is vitreous. it is double refracting and has no cleavage. it is found in china, india, burma, ceylon, south africa, america, and in many other places, having a wide distribution. _the ruby._ in the dichroscope the ruby shows two images, one square of a violet red, the second square being a truer and a paler red. it may be subjected to strong heat, when it changes its colour to a sooty or dirty slate, this varying with the locality in which the stone is found, and the manner in which the heat is applied. but as it cools it becomes paler and greener, till it slowly enrichens; the green first becomes broken, then warmer, redder, and finally assumes its original beautiful blood red. this method of heating is sometimes used as a test, but it is a test which often means the complete ruin of a stone which is not genuine. another characteristic which, in the eyes of the expert, invariably isolates a real from an artificial ruby is its curious mild brilliance, which as yet has not been reproduced by any scientific method in paste or any other material, but perhaps the safest test of all is the crystalline structure, which identical structure appears in no other stone, though it is possible, by heating alumina coloured with oxide of iron and perhaps also a trace of oxide of chromium to a very high temperature for a considerable time, and then cooling very slowly, to obtain a ruby which is nearly the same in its structure as the real gem; its specific gravity and hardness may perhaps be to standard, and when properly cut, its brilliance would deceive all but an expert. and as in some real rubies there are found slight hollows corresponding or analogous to the bubbles found in melted glass, it becomes a matter of great difficulty to distinguish the real from the imitation by such tests as hardness, specific gravity, dichroism, and the like, so that in such a case, short of risking the ruin of the stone, ordinary persons are unable to apply any convincing tests. therefore, only the expert can decide, by his appreciation of the delicate shade of difference in the light of a true ruby and that of an excellent imitation, and by the distribution of the colour, which--however experienced the chemist may be, or with what care the colouring matter may have been incorporated in the mass--has been found impossible of distribution throughout the body of an artificial stone so perfectly and in the same manner and direction as nature herself distributes it in the genuine. this alone, even in the closest imitations, is clear to the eye of the expert, though not to the untrained eye, unless the stone is palpably spurious. to one who is accustomed to the examination of precious stones, however perfect the imitation, it is but necessary to place it beside or amongst one or more real ones for the false to be almost instantly identified, and that with certainty. _the sapphire._ the sapphire is not so easy to imitate, as its hardness exceeds that of the ruby, and imitations containing its known constituents, or of glass, are invariably softer than the natural stone. as before remarked, almost any form of corundum other than red is, broadly, called sapphire, but giving them their strictly correct designations, we have the olivine corundum, called "chrysolite" (oriental), which is harder than the ordinary or "noble" chrysolite, sometimes called the "peridot." the various yellow varieties of corundum take the name of the "oriental topaz," which, like most, if not all, the corundum varieties, is harder than the gem which bears the same name, minus the prefix "oriental." then we have the "amethyst" sapphire, which varies from a red to a blue purple, being richer in colour than the ordinary amethyst, which is a form of violet-coloured quartz, but the corundum variety, which, like its companions, is called the "oriental" amethyst, is both rarer and more precious. a very rare and extremely beautiful green variety is called the oriental emerald. the oriental jacinth, or hyacinth, is a brown-red corundum, which is more stable than the ordinary hyacinth, this latter being a form of zircon; it changes colour on exposure to light, which colour is not restored by subsequent retention in darkness. the blue sapphire is of all shades of blue, from cornflower blue to the very palest tints of this colour, all the gradations from light to dark purple blues, and, in fact, so many shades of tone and colour that they become almost as numerous as the stones. these stones are usually found in similar situations to those which produce the ruby, and often along with them. the lighter colours are usually called females, or feminine stones, whilst the darker ones are called masculine stones. some of these dark ones are so deep as to be almost black, when they are called "ink" sapphires, and if inclining to blue, "indigo" sapphires, in contradistinction to which the palest of the stones are called "water" sapphires. the colouring matter is not always even, but is often spread over the substance of the stone in scabs or "splotches," which rather favours imitation, and, where this unevenness occurs, it may be necessary to cut or divide the stone, or so to arrange the form of it that the finished stone shall be equally blue throughout. in some cases, however, the sapphire may owe its beauty to the presence of two, three or more colours in separate strata appearing in one stone; such as a portion being a green-blue, another a cornflower blue, another perfectly colourless, another a pale sky blue, another yellow, each perfectly distinct, the stone being cut so as to show each colour in its full perfection. this stone, the sapphire, is hardness no. (see "hardness" table), and therefore ranks next to the diamond, which makes it a matter of great difficulty to obtain an imitation which is of the same specific gravity and of the same degree of hardness, though this has been done. such stones are purchasable, but though sold as imitations at comparatively low price, and the buyer may consider them just as good as the real gem, to the experienced eye they are readily detectable. by heating a sapphire its blue colour slowly fades, to complete transparency in many cases, or at any rate to so pale a tint as to pass for a transparent stone. valuable as is the sapphire, the diamond is more so, and it follows that if one of these clear or "cleared" sapphires is cut in the "rose" or "brilliant" form--which forms are reserved almost exclusively for the diamond--such a stone would pass very well as a diamond, and many so cut are sold by unscrupulous people as the more valuable stone, which fraud an expert would, of course, detect. sapphires are mentioned by pliny, and figure largely in the ancient history of china, egypt, rome, etc. the greeks dedicated the sapphire specially to jupiter, and many of the stones were cut to represent the god; it also figured as one of the chief stones worn by the jewish high priest on the breast-plate. some stones have curious rays of variegated colour, due to their crystalline formation, taking the shape of a star; these are called "asteriated," or "cat's eye" sapphires. others have curious flashes of light, technically called a "play" of light (as described in chapter vi. on "colour"), together with a curious blue opalescence; these are the "girasol." another interesting variety of this blue sapphire is one known as "chatoyant"; this has a rapidly changing lustre, which seems to undulate between a green-yellow and a luminous blue, with a phosphorescent glow, or fire, something like that seen in the eyes of a cat in the dark, or the steady, burning glow observed when the cat is fascinating a bird--hence its name. this is not the same variety as the "asteriated," or "cat's eye" or "lynx eye" mentioned above. chapter xiv. various precious stones--_continued._ _the chrysoberyl._ there are certain stones and other minerals which, owing to their possession of numerous microscopically fine cavities, of a globular or tubular shape, have the appearance of "rays" or "stars," and these are called "asteriated." several of such stones have been discussed already in the last chapter, and in addition to these star-like rays, some of the stones have, running through their substance, one or more streaks, perhaps of asbestos or calcite, some being perfectly clear, whilst others are opalescent. when these streaks pass across the star-like radiations they give the stone the appearance of an eye, the rays forming the iris, the clear, opalescent, or black streak closely resembling the slit in a cat's eye, and when these stones are cut _en cabochon_, that is, dome-shaped (see chapter xi. on "cutting"), there is nothing to deflect the light beams back and forth from facet to facet, as in a diamond, so that the light, acting directly on these radiations or masses of globular cavities and on the streak, causes the former to glow like living fire, and the streak appears to vibrate, palpitate, expand, and contract, exactly like the slit in the eye of a cat. there are a considerable number of superstitions in connection with these cat's-eye stones, many people regarding them as mascots, or with disfavour, according to their colour. when possessing the favourite hue or "fire" of the wearer, such as the fire of the opal for those born in october, of the ruby for those born in july, etc., these stones are considered to bring nothing but good luck; to ward off accident, danger, and sudden death; to be a charm against being bitten by animals, and to be a protection from poison, the "evil eye," etc. they figured largely, along with other valuable jewels, in the worship of the ancient egyptians, and have been found in some of the tombs in egypt. they also appeared on the "systrum," which was a sacred instrument used by the ancient egyptians in the performance of their religious rites, particularly in their sacrifices to the goddess isis. this, therefore, may be considered one of their sacred stones, whilst there is some analogy between the cat's-eye stones and the sacred cat of the egyptians which recurs so often in their hieroglyphics; it is well known that our domestic cat is not descended from the wild cat, but from the celebrated cat of egypt, where history records its being "domesticated" at least thirteen centuries b.c. from there it was taken throughout europe, where it appeared at least a century b.c., and was kept as a pet in the homes of the wealthy, though certain writers, speaking of the "mouse-hunters" of the old romans and greeks, state that these creatures were not the egyptian cat, but a carniverous, long-bodied animal, after the shape of a weasel, called "marten," of the species the "beech" or "common" marten (_mustela foina_), found also in britain to-day. it is also interesting to note that the various superstitions existing with regard to the different varieties and colours of cats also exist in an identical manner with the corresponding colours of the minerals known as "cat's eye." several varieties of cat's-eye have already been described. another important variety is that of the chrysoberyl called "cymophane." this is composed of glucina, which is glucinum oxide, or beryllia, beo, of which there is . per cent., and alumina, or aluminium oxide, al_{ }o_{ }, of which there is . per cent. it has, therefore, the chemical formula, beo,al_{ }o_{ }. this stone shows positive electricity when rubbed, and, unlike the sapphires described in the last chapter, which lose their colour when heated, this variety of chrysoberyl shows no change in colour, and any electricity given to it, either by friction or heat, is retained for a long time. when heated in the blowpipe alone it remains unaltered, that is, it is not fusible, and even with microcosmic salt it requires a considerably long and fierce heat before it yields and fuses, and acids do not act upon it. it crystallises in the th (rhombic) system, and its lustre is vitreous. the cymophane shows a number of varieties, quite as many as the chrysoberyl, of which it is itself a variety, and these go through the gamut of greens, from a pale white green to the stronger green of asparagus, and through both the grey and yellow greens to dark. it is found in ceylon, moravia, the ural mountains, brazil, north america, and elsewhere. the cat's-eye of this is very similar to the quartz cat's-eye, but a comparison will make the difference so clear that they could never be mistaken, apart from the fact that the quartz has a specific gravity considerably lower than the chrysoberyl cat's-eye, which latter is the true cat's-eye, and the one usually understood when allusion is made to the stone without any distinguishing prefix, such as the ruby, sapphire, quartz, etc., cat's eye. it should, however, be mentioned that this stone is referred to when the names ceylonese and oriental cat's-eye are given, which names are used in the trade as well as the simple appellation, "cat's eye." one peculiarity of some of these stones is that the "fire" or "glow" is usually altered in colour by the colour of the light under which it is seen, the change of colour being generally the complementary. thus, a stone which in one light shows red, in another will be green; the "eye" showing blue in one light will become orange in another; whilst the yellow of another stone may show a decided purple or amethyst in a different light. a good test for this, and indeed most precious stones, is that they conduct heat more quickly than does glass, and with such rapidity that on breathing upon a stone the warmth is conducted instantly, so that, though the stone is dimmed the dimness vanishes at once, whereas with glass the film of moisture fades but slowly in comparison. _the topaz._ the name topaz is derived from the greek _topazos_, which is the name of a small island situated in the gulf of arabia, from whence the romans obtained a mineral which they called topazos and topazion, which mineral to-day is termed chrysolite. the mineral topaz is found in cornwall and in the british isles generally; also in siberia, india, south america and many other localities, some of the finest stones coming from saxony, bohemia, and brazil, especially the last-named. the cleavage is perfect and parallel to the basal plane. it crystallises in the th (rhombic) system; in lustre it is vitreous; it is transparent, or ranging from that to translucent; the streak is white or colourless. its colour varies very much--some stones are straw-colour, some are grey, white, blue, green, and orange. a very favourite colour is the pink, but in most cases this colour is not natural to the stone, but is the result of "burning," or "pinking" as the process is called technically, which process is to raise the temperature of a yellow stone till the yellow tint turns to a pink of the colour desired. the topaz is harder than quartz, as will be seen on reference to the "hardness" table, and is composed of a silicate of aluminium, fluorine taking the place of some of the oxygen. its composition averages . per cent. of silica, . per cent. of alumina, or oxide of aluminium, and fluoride of silicium, per cent. its formula is [al(f,oh)]_{ } sio_{ }, or (alf)_{ }sio_{ }. from this it will be understood that the fluorine will be evolved when the stone is fused. it is, however, very difficult to fuse, and alone it is infusible under the blowpipe, but with microcosmic salt it fuses and evolves fluorine, and the glass of the tube in the open end of which the stone is fixed is bitten with the gas. such experiments with the topaz are highly interesting, and if we take a little of the powdered stone and mix with it a small portion of the microcosmic salt, we may apply the usual test for analysing and proving aluminium, thus: a strongly brilliant mass is seen when hot, and if we moisten the powder with nitrate of cobalt and heat again, this time in the inner flame, the mass becomes blue. other phenomena are seen during the influence of heat. some stones, as stated, become pink on heating, but if the heating is continued too long, or too strongly, the stone is decoloured. others, again, suffer no change, and this has led to a slight difference of opinion amongst chemists as to whether the colour is due to inorganic or organic matter. heating also produces electricity, and the stone, and even splinters of it, will give out a curious phosphorescent light, which is sometimes yellow, sometimes blue, or green. friction or pressure produces strong electrification; thus the stones may be electrified by shaking a few together in a bag, or by the tumbling of the powdered stone-grains over each other as they roll down a short inclined plane. the stones are usually found in the primitive rocks, varying somewhat in different localities in their colour; many of the brazilian stones, when cut as diamonds, are not unlike them. in testing, besides those qualities already enumerated, the crystalline structure is specially perfect and unmistakable. it is doubly refractive, whereas spinel and the diamond, which two it closely resembles, are singly refractive. topaz is readily electrified, and, if perfect at terminals, becomes polarised; also the commercial solution of violets, of which a drop only need be taken for test, is turned green by adding to it a few grains of topaz dust, or of a little splinter crushed to fine powder. _the beryl._ the beryl is a compound of silicates of beryllia and alumina, with the formula beosio_{ } + al_{ }o_{ }, sio_{ }, or beo,al_{ }o_{ }, sio_{ }. it differs very little indeed from the emerald, with the exception of its colour. in the ordinary varieties this is somewhat poor, being mostly blue, or a dirty or a greenish yellow; the better kinds, however, possess magnificent colour and variety, such as in the aquamarine, emerald, etc. the cleavage is parallel to the basal plane. its lustre is sometimes resinous, sometimes vitreous, and it crystallises in the nd (hexagonal) system. it occurs in somewhat long, hexagonal prisms, with smooth, truncated planes, and is often found in granite and the silt brought down by rivers from granite, gneiss, and similar rocks. it is found in great britain and in many parts of europe, asia, and america, in crystals of all sizes, from small to the weight of several tons. the common kinds are too opaque and colourless to be used as gems and are somewhat difficult of fusion under the blowpipe, on the application of which heat some stones lose their colour altogether, others partly; others, which before heating were somewhat transparent, become clouded and opaque; others suffer no change in colour, whilst some are improved. in almost every case a slight fusion is seen on the sharp edges of fractures, which become smooth, lose their sharpness, and have the appearance of partly fused glass. the hardness varies from - / to , the crystals being very brittle, breaking with a fracture of great unevenness. the better varieties are transparent, varying from that to translucent, and are called the "noble" beryls. transparent beryl crystals are used by fortune-tellers as "gazing stones," in which they claim to see visions of future events. _the emerald._ considering the particular emerald which is a variety of beryl--although the name emerald in the trade is applied somewhat loosely to any stone which is of the same colour, or approaching the colour of the beryl variety--this emerald only differs chemically from the beryl, just described, in possessing an addition of oxide of chromium. in shape, crystallisation, fracture and hardness, it is the same, and often contains, in addition to the chromium, the further addition of traces of carbonate of lime, magnesia, and occasionally faint traces of hornblende and mica, which evidently result from its intimate association with the granite rock and gneiss, amongst which it is mostly found, the latter rocks being of a slaty nature, in layers or plates, and, like granite, containing mica, pyrites, felspar, quartz, etc. emeralds have been known from very early times, and are supposed to have been found first in the mines of ancient egypt. they were considered amongst the rarest and the most costly of gems, and it was the custom, when conferring lavish honour, to engrave or model emeralds for presentation purposes. thus we find pliny describes ptolemy giving lucullus, on his landing at alexandria, an emerald on which was engraved his portrait. pliny also relates how the short-sighted nero watched the fights of gladiators through an eye-glass made of an emerald, and in ancient times, in rome, greece, and egypt, eye-glasses made of emeralds were much valued. many of these, as well as engraved and carved emeralds, have been discovered in ruins and tombs of those periods. the copper emerald is rare; it is a hydrous form of copper silicate, cuosio_{ } + h_{ }o, of a beautiful emerald green, varying from transparent to translucent. it exhibits double refraction, and is a crystallised mineral, brittle, and showing a green streak. this is less hard than the real emerald, is heavier, deeper in colour, and is usually found in crystals, in cavities of a particular kind of limestone which exists at altyn-tübe, a hill in the altai mountains, in the urals, and in north and central america. _the tourmaline._ the tourmaline is a most complex substance; almost every stone obtained has a different composition, some varying but slightly, with mere traces of certain constituents which other stones possess in a perceptible degree. consequently, it is not possible to give the chemical formula, which might, and possibly would, be found but seldom, even in analyses of many specimens. it will therefore be sufficient to state the average composition, which is:--ferrous oxide, manganous oxide, potash, lime, boracic acid, magnesia, soda, lithia, and water. these form, roughly speaking, per cent. of the bulk, the remainder being oxide of silicon and oxide of aluminium in about equal parts. it crystallises in the nd (hexagonal) system, with difficult cleavage and vitreous lustre. it will naturally be expected that a substance of such complexity and variety of composition must necessarily have a corresponding variety of colour; thus we find in this, as in the corundum, a wonderful range of tints. the common is the black, which is not used as a gem. next come the colourless specimens, which are not often cut and polished, whereas all the transparent and coloured varieties are in great demand. to describe adequately their characteristics with relation to light would alone require the space of a complete volume, and the reader is referred to the many excellent works on physics (optics) which are obtainable. this stone is doubly refracting, exhibiting extremely strong dichroism, especially in the blue and the green varieties. it polarises light, and when viewed with the dichroscope shows a remarkable variety of twin colours. it will be remembered that in hogarth's "rake's progress," the youth is too engrossed in the changing wonders of a tourmaline to notice the entrance of the officers come to arrest him. chapter xv. various precious stones--_continued_. _zircon._ zircon appears to have been first discovered by klaproth in , in the form of an earth, and six years later he found that the stone hyacinth contained a similar substance, both having the formula, zrsio_{ }, and both having as their colouring agent ferric oxide. there are several methods of obtaining the metallic element, zirconium; it is however with the silicate of zirconium that we have to deal at the moment. this is called zircon, zrsio_{ }, or hyacinth when transparent or red, but when smoke-coloured, or colourless, it is the jargoon, or jarcon, and is found in silt and alluvial soils, limestone, gneiss, and various forms of schist, in india, australia, the urals, and certain parts of america. it is often combined with and found in juxtaposition to gold and certain varieties of precious stones. the lines of cleavage are parallel to the sides of the prism, and the crystals have an adamantine, or diamond lustre, varying from the completely opaque to the transparent. in some varieties the oxide of uranium is also present in traces. it crystallises in the rd (tetragonal) system, with indistinct cleavage. its specific gravity varies from . to . , according to the specimen and the locality. this stone, like some of the others described, has a very wide range of colour, going through reds, browns, greens, yellows, oranges, whites, greys, blues from light to indigo, notwithstanding which it is somewhat difficult to imitate scientifically, though its composition of per cent. of silica with per cent. of zirconia (the oxide of zirconium), is practically all it contains, apart from the colouring matter, such as the metallic oxides of iron, uranium, etc. its hardness is - / , consequently it is untouched by a file, and so far, if one or perhaps two of the three qualities of colour, hardness, and specific gravity, are obtained in a chemically made zircon, the third is wanting. under the blowpipe, zircons are infusible, but the coloured stones when heated strongly become heavier, and as they are contracting, their colour fades, sometimes entirely, which changes are permanent, so that as they possess the adamantine lustre, they are occasionally cut like a diamond, and used as such, though their deficiency in fire and hardness, and their high specific gravity, make them readily distinguishable from the diamond. on exposure to light the coloured zircon becomes more or less decoloured; especially is this so in sunlight, for when the direct rays of the sun fall upon it, the colours fade, and for a moment or two occasional phosphorescence follows, as is the case when the stone is warmed or heated in a dark room. the stone appears to be very susceptible to brilliant light-rays, and in certain specimens which were split for testing, one half of each being kept excluded from light for purposes of comparison, it was found that sunshine affected them most; then brilliant acetylene gas, which was more effective still when tinted yellow by being passed through yellow glass. the electric arc was not so effective, but the electric light of the mercury-vapour lamp, though causing little change at the first, after a few hours' exposure rapidly bleached certain of the colours, whilst having no effect on others. coal gas with incandescent fibre mantle was slightly effective, whilst the coal-gas, burned direct through an ordinary burner, affected very few of the colours, even after twenty-four hours' exposure at a distance of three feet. in all these cases, though the colours were slightly improved by the stones being kept for a time in the dark, they failed to recover their original strength, showing permanent loss of colour. _the silicates._ the chief of these are the garnets, crystallising in the cubic system, and anhydrous. the garnet is usually in the form of a rhombic dodecahedron, or as a trisoctahedron (called also sometimes an icosatetrahedron), or a mixture of the two, though the stones appear in other cubic forms. in hardness they vary from - / to - / . they average from to about per cent. of silica, the other ingredients being in fairly constant and definite proportions. they are vitreous and resinous in their lustre and of great variety of colour, chiefly amongst reds, purples, violets, greens, yellows and blacks, according to the colouring matter present in their mass. there are many varieties which are named in accordance with one or more of their constituents, the best known being: (a) the iron-alumina garnet, having the formula feo, sio_{ } + al_{ }o_{ }, sio_{ }. this is the "precious" garnet, or almandine, sometimes called the "oriental" garnet; these stones are found in great britain, india, and south america, and are deep red and transparent, of vitreous lustre. they get up well, but certain varieties are so subject to defects in their substance, brought about by pressure, volcanic action, and other causes, some of which are not yet known, that their quality often becomes much depreciated in consequence. this inferior variety of the iron-alumina garnet is called the "common" garnet, and has little lustre, being sometimes opaque. the perfect qualities, or almandine, as described above, are favourite stones with jewellers, who mount great quantities of them. the second variety is the (b) lime-iron garnet, formula, cao, sio_{ } + fe_{ }o_{ }, sio_{ }. the chief of this class is the melanite, sometimes dull, yet often vitreous; it is mostly found in volcanic rocks, such as tuff; this variety is very popular with jewellers for mourning ornaments, for as it is a beautiful velvet-black in colour and quite opaque, it is pre-eminent for this purpose, being considerably less brittle than jet, though heavier. another variety is the "topazolite," both yellow and green. the "aplome" is greenish-yellow, yellowish-green, brown, and usually opaque. a further form of lime-iron garnet is the "pyreneite," first found in the pyrenees mountains, hence its name. the (c) lime-chrome garnets-- cao, sio_{ } + cr_{ }o_{ }, sio_{ }--the chief of which is "uwarowite." this is of a magnificent emerald green colour, translucent at edges and of a vitreous lustre. when heated on the borax bead it gives an equally beautiful green, which is, however, rather more inclined to chrome than emerald. this is an extremely rare stone in fine colour, though cloudy and imperfect specimens are often met with, but seldom are large stones found without flaws and of the pure colour, which rivals that of the emerald in beauty. the fourth variety (d) is the lime-alumina garnet, its formula being-- cao, sio_{ } + al_{ }o_{ }, sio_{ }. like the others, it has a number of sub-varieties, the chief being the "cinnamon stone," which is one of great beauty and value when perfect. this stone is almost always transparent when pure, which property is usually taken as one of the tests of its value, for the slightest admixture or presence of other substances cloud it, probably to opacity, in accordance with the quantity of impurity existent. this variety is composed of the oxides of aluminium and silicon with lime. in colour it ranges from a beautiful yellowish-orange deepening towards the red to a pure and beautiful red. "romanzovite" is another beautiful variety, the colour of which ranges through browns to black. another important variety is the "succinite," which gets up well and is a favourite with jewellers because of its beautiful, amber-like colour, without possessing any of the drawbacks of amber. (e) the magnesia-alumina garnet-- mgo, sio_{ } + al_{ }o_{ }, sio_{ }--is somewhat rare, the most frequently found being of a strong crimson colour and transparent. this variety is called "pyrope," the deeper and richer tints being designated "carbuncle," from the latin _carbunculus_, a little coal, because when this beautiful variety of the "noble" garnet is held up between the eyes and the sun, it is no longer a deep, blood-red, but has exactly the appearance of a small piece of live or glowing coal, the scarlet portion of its colour-mixture being particularly evident. the ancient greeks called it anthrax, which name is sometimes used in medicine to-day with reference to the severe boil-like inflammation which, from its burning and redness, is called a carbuncle, though it is more usual to apply the word "anthrax" to the malignant cattle-disease which is occasionally passed on to man by means of wool, hair, blood-clots, etc., etc., and almost always ends fatally. a great deal of mystery and superstition has always existed in connexion with this stone--the invisibility of the bearer of the egg-carbuncle laid by a goldfinch, for instance. (f) the manganese-alumina garnet-- mno, sio_{ } + al{ }o_{ }, sio_{ }--is usually found in a crystalline or granular form, and mostly in granite and in the interstices of the plates, or laminæ, of rocks called schist. one variety of this, which is a deep hyacinth in colour, though often of a brown-tinted red, is called "spessartine," or "spessartite," from the district in which it is chiefly found, though its distribution is a fairly wide one. _the lapis-lazuli._ the lapis-lazuli, sometimes called "azure stone," is almost always blue, though often containing streaks of white and gold colour, the latter of which are due to the presence of minute specks or veins of iron pyrites, the former and colourless streaks being due to free lime, calcite, and other substances which have become more or less blended with the blue colour of the stone. it has a vitreous lustre, crystallises in the st, or cubic system, and is a complex substance, varying considerably in its ingredients in accordance with the locality in which it is found, its matrix, and the general geological formation of the surrounding substances, which may, by the penetration of moisture, be brought to bear upon the stone, thus influencing to a great extent its chemical composition. so that we find the stone composed of about a quarter of its substance of alumina, or oxide of aluminium, silica to the extent of almost half, the remainder being lime, soda, sulphur, and occasionally traces of copper and iron. it is mostly found in granite and certain crystalline limestone rocks, in fairly large masses. it is of great antiquity, figuring extensively in ancient egyptian history, both in its form as a stone and ground up into a pigment for the decoration of sacred and royal vessels and appointments. when so ground, it forms the stable and magnificent colour, _genuine_ ultramarine, which is the finest and purest blue on the artist's palette, but owing to its extremely high price its use is not in very great demand, especially as many excellent chemical substitutes of equal permanence are obtainable at little cost. _the turquoise._ the turquoise is a pseudomorph (see chapter iv., "cleavage.") in colour it is blue or greenish-blue, sometimes opaque, varying between that and feeble translucency, though it should be said that in all forms, even those considered opaque, a thin cutting of the stone appears almost transparent, so that the usual classing of it among the opaque stones must be done with this reservation. in composition it contains about per cent. of water, about a third of its substance being phosphoric acid, or phosphorus-pentoxide; sometimes nearly half of it is alumina, with small quantities of iron in the form of variously coloured oxides, with oxide of manganese. the great proportion of water, which it seems to take up during formation, is mostly obtained in the cavities of weathered and moisture-decomposing rocks. its average formula may be said to be al_{ }o_{ }p_{ }o_{ } + h_{ }o, and sometimes al_{ }o_{ } feop_{ }o_{ } + h_{ }o. it must therefore follow that when the stone is heated, this water will separate and be given off in steam, which is found to be the case. the water comes off rapidly, the colour of the stone altering meanwhile from its blue or blue-green to brown. if the heat is continued sufficiently long, this brown will deepen to black, while the flame is turned green. this is one of the tests for turquoise, but as the stone is destroyed in the process, the experiment should be made on a splinter from it. this stone is of very ancient origin, and many old turquoise deposits, now empty, have been discovered in various places. history records a magnificent turquoise being offered in russia for about £ a few centuries ago, which is a very high price for these comparatively common stones. owing to the presence of phosphorus in bones, it is not uncommon to find, in certain caves which have been the resort of wild animals, or into which animals have fallen, that bones in time become subjected to the oozing and moisture of their surroundings; alumina, as well as the oxides of copper, manganese and iron, are often washed across and over these bones lying on the cave floor, so that in time, this silt acts on the substance of the bones, forming a variety of turquoise of exactly the same composition as that just described, and of the same colour. so that around the bones there eventually appears a beautiful turquoise casing; the bone centre is also coloured like its casing, though not entirely losing its bony characteristics, so that it really forms a kind of ossified turquoise, surrounded by real turquoise, and this is called the "bone turquoise" or "odontolite." index adamantine lustre, glimmering, glinting, or glistening, lustreless, shining, splendent, agate, almandine, amethyst, oriental, sapphire, amorphous stones and their characteristics, analysis, aplome, asters, or asteriated stones, , - azure-stone, beryl, , colours of, in dichroscope, beryllium, bezils, black stones, list of, blue sapphire, composition of the, stones, list of, bone-turquoise, break, as opposed to cleavage, brilliant-cut stones, brown stones, list of, building up of crystals, burnt, or pinked topaz, cabochon-cut stones, (the double), (the hollow), carbonate series, carbuncle, , cat of egypt, cat's eye stones, , - list of (see "chatoyant stones"), ceylonese cat's eye (see "cat's eye") change of colour (not to be confused with "play of colour" and "opalescence," which see; see also "fire"), characteristics of precious stones, , chatoyant stones, list of, chemical illustration of formation of precious stones, chloride of palladium in dichroscope, chrysoberyl, chrysolite, ordinary, or "noble", oriental, cinnamon stone, claims of precious stones, cleavage affecting tests, and "cleavage" as opposed to "break", , colour, , , , colourless stones, list of, colours and characteristics of the various opals, , of precious stones, list of, - common garnet, opal, composite crystals, composition of paste, or strass, for imitation stones, composition of precious stones, converted stones, corundum, crown portion of stones, , crystalline structure, physical properties, of crystallography, crystals, axes of symmetry, groups of, , planes of symmetry, systems of, ( ) cubic--isometric, monometric, regular, ( ) hexagonal--rhombohedral, ( ) tetragonal--quadratic, square prismatic, dimetric, pyramidal, ( ) rhombic--orthorhombic, prismatic, trimetric, ( ) monoclinic--clinorhombic, monosymmetric, oblique, , ( ) triclinic--anorthic, asymmetric, , treatment of, culasse portion of stones, cullinan diamond (see also "stars of africa"), , , , cutting of precious stones, , , cymophane, definition of a precious stone, diamond, characteristics of the, composition of the, (sapphire), unique, (zircon), diaphaneity, , diaphanous stones, dichroscope, how to make a, how to use a, dimorphism in precious stones, double cabochon-cut stones, refraction (see "refraction") doublets, electric and magnetic influences, experiments with precious stones and pithball and electroscope, experiments with tourmaline, , emerald, , , , oriental, en cabochon-cut stones, experiments to show electric polarity, , facets in stones, description of the, , feminine stones, fire in stones (see also "change of colour," "opalescence," and "play of colour"), , fire opal, flame-coloured stones, list of, flaws, formation of precious stones, , chemical illustration of, , garnet, , garnets (a) iron-alumina (called also almandine and precious or oriental garnet), sub-variety, common garnet, (b) lime-iron, sub-variety aplome, melanite, pyreneite, topazolite, (c) lime-chrome, , sub-variety uwarowite, , (d) lime-alumina, sub-variety cinnamon stone, romanzovite, succinite, (e) magnesia-alumina, , sub-variety carbuncle, or anthrax, , noble, pyrope, (f) manganese-alumina, sub-variety spessartine, or spessartite, girdle portion of a stone, glimmering, in lustre, definition of, glinting, or glistening in lustre, definition of, _goutte de suif_-cut stones, great mogul diamond, green stones, list of, groups of crystals (see "crystals") hardness, physical properties of, table of, , , heat indexes, physical properties of, hollow-cabochon, hyacinth, ordinary (a form of zircon), , oriental, hyalite (opal), hydrophane (opal), imitations and tests of precious stones, indigo sapphires, ink sapphires, iridescence, and cause of, , iron-alumina garnets, jacinth, oriental, jarcon, or jargoon, koh-i-nûr, lapis-lazuli, light, physical properties of, lime-alumina garnets, cinnamon stone, romanzovite, succinite, lime-chrome garnets, , uwarowite, , lime-iron garnets, aplome, pyreneite, topazolite, list of stones according to colour, - hardness, - specific gravity, - lustre, , lustreless, definition of, lynx-eye stones, magnesia-alumina garnets, , carbuncle, or anthrax, noble, pyrope, magnetic and electric influences, - malachite, manganese-alumina garnets, spessartine, or spessartite, masculine stones, melanite, menilite (opal), metallic-lustre stones, , mohs's table of hardness, - noble garnet, or precious opal, non-diaphanous stones, odontolite, olivine corundum (see "chrysolite"), opal, varieties of, , opalescence (not to be confused with "change of colour" and "play of colour," which see; see also "fire"), , oriental amethyst, cat's eye (see "cat's eye") emerald, garnet, topaz, origin of precious stones, paste, or strass, for imitation stones, composition of, pavilion portion of cut stones, pearly-lustre stones, , peridot (see "noble chrysolite"), pink-coloured stones, list of (see also red), pinked topaz, phosphorescence, , physical properties:-- a.--crystalline structure, b.--cleavage, c.--light, d.--colour, e.--hardness, f.--specific gravity, g.--heat, h.--magnetic and electric influences, play of colour (not to be confused with "change of colour" and "opalescence," which see; see also "fire"), , pleochroism, polarisation, electric, , of light, , polariscope, , polishing precious stones, , polymorphism in precious stones, precious, or noble opal, pseudomorphism in precious stones, , pyreneite, pyro-electricity, development and behaviour of, - pyrope, qualities of precious stones, , red and rose-coloured stones, list of (see also pink), , reflection of light, , refraction of heat, - light, , reproduction of crystalline form, , resinous lustre stones, , rock-crystal, romanzovite, rose-coloured stones (see red, above), , rose, or rosette-cut stones, rothschild's testing solution, ruby, characteristics of, composition of, sapphire, amethyst, and its varieties, , cleared, diamonds, indigo, ink, the blue, composition of, , water, semi-diaphanous stones, shining, in lustre, definition of, silica group, composition of the, silicates, silky-lustre stones, , single-refraction (see "refraction") south african diamond (see "cullinan diamond") specific gravity, splendent, in lustre, definition of, splitting of the cullinan diamond, star-portion of stones, stars of africa (see also "cullinan diamond"), , , starting or splitting of stones on cleavage planes, step-cut stones, stones arranged according to colour, - hardness, - specific gravity, - strass for imitation stones, composition of, sub-metallic in lustre, definition of, sub-translucent stones, sub-transparent stones, succinite, synthesis, systems of crystals (see "crystals") table-cut stones, tallow drops, teeth of stone, testing by crystalline structure, hardness, , with needles, gems by dichroscope, , solution (rothschild's), tests of precious stones (general), topaz, , colours of, in dichroscope, oriental, topazolite, tourmaline, , electric experiments with, , translucent stones, transmission of heat, - light, transparent stones, trap-cut stones, tri-morphism in precious stones, triplets, turquoise, (bone), composition of the, odontolite, uwarowite, , violet stones, list of, vitreous-lustre stones, , water-sapphires, white (paste) stones, stones, list of, yellow stones, list of, topaz, zircon, , diamonds, zirconium, london: printed by william clowes and sons, limited, great windmill street, w., and duke street, stamford street, s. e. none transcribed from the macmillan and co. edition by david price, email ccx @coventry.ac.uk madam how and lady why or, first lessons in earth lore for children dedication to my son grenville arthur, and to his school-fellows at winton house this little book is dedicated. preface my dear boys,--when i was your age, there were no such children's books as there are now. those which we had were few and dull, and the pictures in them ugly and mean: while you have your choice of books without number, clear, amusing, and pretty, as well as really instructive, on subjects which were only talked of fifty years ago by a few learned men, and very little understood even by them. so if mere reading of books would make wise men, you ought to grow up much wiser than us old fellows. but mere reading of wise books will not make you wise men: you must use for yourselves the tools with which books are made wise; and that is--your eyes, and ears, and common sense. now, among those very stupid old-fashioned boys' books was one which taught me that; and therefore i am more grateful to it than if it had been as full of wonderful pictures as all the natural history books you ever saw. its name was _evenings at home_; and in it was a story called "eyes and no eyes;" a regular old-fashioned, prim, sententious story; and it began thus:-- "well, robert, where have you been walking this afternoon?" said mr. andrews to one of his pupils at the close of a holiday. oh--robert had been to broom heath, and round by camp mount, and home through the meadows. but it was very dull. he hardly saw a single person. he had much rather have gone by the turnpike-road. presently in comes master william, the other pupil, dressed, i suppose, as wretched boys used to be dressed forty years ago, in a frill collar, and skeleton monkey-jacket, and tight trousers buttoned over it, and hardly coming down to his ancles; and low shoes, which always came off in sticky ground; and terribly dirty and wet he is: but he never (he says) had such a pleasant walk in his life; and he has brought home his handkerchief (for boys had no pockets in those days much bigger than key- holes) full of curiosities. he has got a piece of mistletoe, wants to know what it is; and he has seen a woodpecker, and a wheat-ear, and gathered strange flowers on the heath; and hunted a peewit because he thought its wing was broken, till of course it led him into a bog, and very wet he got. but he did not mind it, because he fell in with an old man cutting turf, who told him all about turf-cutting, and gave him a dead adder. and then he went up a hill, and saw a grand prospect; and wanted to go again, and make out the geography of the country from cary's old county maps, which were the only maps in those days. and then, because the hill was called camp mount, he looked for a roman camp, and found one; and then he went down to the river, saw twenty things more; and so on, and so on, till he had brought home curiosities enough, and thoughts enough, to last him a week. whereon mr. andrews, who seems to have been a very sensible old gentleman, tells him all about his curiosities: and then it comes out--if you will believe it--that master william has been over the very same ground as master robert, who saw nothing at all. whereon mr. andrews says, wisely enough, in his solemn old-fashioned way,-- "so it is. one man walks through the world with his eyes open, another with his eyes shut; and upon this difference depends all the superiority of knowledge which one man acquires over another. i have known sailors who had been in all the quarters of the world, and could tell you nothing but the signs of the tippling-houses, and the price and quality of the liquor. on the other hand, franklin could not cross the channel without making observations useful to mankind. while many a vacant thoughtless youth is whirled through europe without gaining a single idea worth crossing the street for, the observing eye and inquiring mind find matter of improvement and delight in every ramble. you, then, william, continue to use your eyes. and you, robert, learn that eyes were given to you to use." so said mr. andrews: and so i say, dear boys--and so says he who has the charge of you--to you. therefore i beg all good boys among you to think over this story, and settle in their own minds whether they will be eyes or no eyes; whether they will, as they grow up, look and see for themselves what happens: or whether they will let other people look for them, or pretend to look; and dupe them, and lead them about--the blind leading the blind, till both fall into the ditch. i say "good boys;" not merely clever boys, or prudent boys: because using your eyes, or not using them, is a question of doing right or doing wrong. god has given you eyes; it is your duty to god to use them. if your parents tried to teach you your lessons in the most agreeable way, by beautiful picture-books, would it not be ungracious, ungrateful, and altogether naughty and wrong, to shut your eyes to those pictures, and refuse to learn? and is it not altogether naughty and wrong to refuse to learn from your father in heaven, the great god who made all things, when he offers to teach you all day long by the most beautiful and most wonderful of all picture-books, which is simply all things which you can see, hear, and touch, from the sun and stars above your head to the mosses and insects at your feet? it is your duty to learn his lessons: and it is your interest. god's book, which is the universe, and the reading of god's book, which is science, can do you nothing but good, and teach you nothing but truth and wisdom. god did not put this wondrous world about your young souls to tempt or to mislead them. if you ask him for a fish, he will not give you a serpent. if you ask him for bread, he will not give you a stone. so use your eyes and your intellect, your senses and your brains, and learn what god is trying to teach you continually by them. i do not mean that you must stop there, and learn nothing more. anything but that. there are things which neither your senses nor your brains can tell you; and they are not only more glorious, but actually more true and more real than any things which you can see or touch. but you must begin at the beginning in order to end at the end, and sow the seed if you wish to gather the fruit. god has ordained that you, and every child which comes into the world, should begin by learning something of the world about him by his senses and his brain; and the better you learn what they can teach you, the more fit you will be to learn what they cannot teach you. the more you try now to understand _things_, the more you will be able hereafter to understand men, and that which is above men. you began to find out that truly divine mystery, that you had a mother on earth, simply by lying soft and warm upon her bosom; and so (as our lord told the jews of old) it is by watching the common natural things around you, and considering the lilies of the field, how they grow, that you will begin at least to learn that far diviner mystery, that you have a father in heaven. and so you will be delivered (if you will) out of the tyranny of darkness, and distrust, and fear, into god's free kingdom of light, and faith, and love; and will be safe from the venom of that tree which is more deadly than the fabled upas of the east. who planted that tree i know not, it was planted so long ago: but surely it is none of god's planting, neither of the son of god: yet it grows in all lands and in all climes, and sends its hidden suckers far and wide, even (unless we be watchful) into your hearts and mine. and its name is the tree of unreason, whose roots are conceit and ignorance, and its juices folly and death. it drops its venom into the finest brains; and makes them call sense, nonsense; and nonsense, sense; fact, fiction; and fiction, fact. it drops its venom into the tenderest hearts, alas! and makes them call wrong, right; and right, wrong; love, cruelty; and cruelty, love. some say that the axe is laid to the root of it just now, and that it is already tottering to its fall: while others say that it is growing stronger than ever, and ready to spread its upas-shade over the whole earth. for my part, i know not, save that all shall be as god wills. the tree has been cut down already again and again; and yet has always thrown out fresh shoots and dropped fresh poison from its boughs. but this at least i know: that any little child, who will use the faculties god has given him, may find an antidote to all its poison in the meanest herb beneath his feet. there, you do not understand me, my boys; and the best prayer i can offer for you is, perhaps, that you should never need to understand me: but if that sore need should come, and that poison should begin to spread its mist over your brains and hearts, then you will be proof against it; just in proportion as you have used the eyes and the common sense which god has given you, and have considered the lilies of the field, how they grow. c. kingsley. chapter i--the glen you find it dull walking up here upon hartford bridge flat this sad november day? well, i do not deny that the moor looks somewhat dreary, though dull it need never be. though the fog is clinging to the fir-trees, and creeping among the heather, till you cannot see as far as minley corner, hardly as far as bramshill woods--and all the berkshire hills are as invisible as if it was a dark midnight--yet there is plenty to be seen here at our very feet. though there is nothing left for you to pick, and all the flowers are dead and brown, except here and there a poor half-withered scrap of bottle-heath, and nothing left for you to catch either, for the butterflies and insects are all dead too, except one poor old daddy-long-legs, who sits upon that piece of turf, boring a hole with her tail to lay her eggs in, before the frost catches her and ends her like the rest: though all things, i say, seem dead, yet there is plenty of life around you, at your feet, i may almost say in the very stones on which you tread. and though the place itself be dreary enough, a sheet of flat heather and a little glen in it, with banks of dead fern, and a brown bog between them, and a few fir-trees struggling up--yet, if you only have eyes to see it, that little bit of glen is beautiful and wonderful,--so beautiful and so wonderful and so cunningly devised, that it took thousands of years to make it; and it is not, i believe, half finished yet. how do i know all that? because a fairy told it me; a fairy who lives up here upon the moor, and indeed in most places else, if people have but eyes to see her. what is her name? i cannot tell. the best name that i can give her (and i think it must be something like her real name, because she will always answer if you call her by it patiently and reverently) is madam how. she will come in good time, if she is called, even by a little child. and she will let us see her at her work, and, what is more, teach us to copy her. but there is another fairy here likewise, whom we can hardly hope to see. very thankful should we be if she lifted even the smallest corner of her veil, and showed us but for a moment if it were but her finger tip--so beautiful is she, and yet so awful too. but that sight, i believe, would not make us proud, as if we had had some great privilege. no, my dear child: it would make us feel smaller, and meaner, and more stupid and more ignorant than we had ever felt in our lives before; at the same time it would make us wiser than ever we were in our lives before--that one glimpse of the great glory of her whom we call lady why. but i will say more of her presently. we must talk first with madam how, and perhaps she may help us hereafter to see lady why. for she is the servant, and lady why is the mistress; though she has a master over her again--whose name i leave for you to guess. you have heard it often already, and you will hear it again, for ever and ever. but of one thing i must warn you, that you must not confound madam how and lady why. many people do it, and fall into great mistakes thereby,--mistakes that even a little child, if it would think, need not commit. but really great philosophers sometimes make this mistake about why and how; and therefore it is no wonder if other people make it too, when they write children's books about the wonders of nature, and call them "why and because," or "the reason why." the books are very good books, and you should read and study them: but they do not tell you really "why and because," but only "how and so." they do not tell you the "reason why" things happen, but only "the way in which they happen." however, i must not blame these good folks, for i have made the same mistake myself often, and may do it again: but all the more shame to me. for see--you know perfectly the difference between how and why, when you are talking about yourself. if i ask you, "why did we go out to-day?" you would not answer, "because we opened the door." that is the answer to "how did we go out?" the answer to why did we go out is, "because we chose to take a walk." now when we talk about other things beside ourselves, we must remember this same difference between how and why. if i ask you, "why does fire burn you?" you would answer, i suppose, being a little boy, "because it is hot;" which is all you know about it. but if you were a great chemist, instead of a little boy, you would be apt to answer me, i am afraid, "fire burns because the vibratory motion of the molecules of the heated substance communicates itself to the molecules of my skin, and so destroys their tissue;" which is, i dare say, quite true: but it only tells us how fire burns, the way or means by which it burns; it does not tell us the reason why it burns. but you will ask, "if that is not the reason why fire burns, what is?" my dear child, i do not know. that is lady why's business, who is mistress of mrs. how, and of you and of me; and, as i think, of all things that you ever saw, or can see, or even dream. and what her reason for making fire burn may be i cannot tell. but i believe on excellent grounds that her reason is a very good one. if i dare to guess, i should say that one reason, at least, why fire burns, is that you may take care not to play with it, and so not only scorch your finger, but set your whole bed on fire, and perhaps the house into the bargain, as you might be tempted to do if putting your finger in the fire were as pleasant as putting sugar in your mouth. my dear child, if i could once get clearly into your head this difference between why and how, so that you should remember them steadily in after life, i should have done you more good than if i had given you a thousand pounds. but now that we know that how and why are two very different matters, and must not be confounded with each other, let us look for madam how, and see her at work making this little glen; for, as i told you, it is not half made yet. one thing we shall see at once, and see it more and more clearly the older we grow; i mean her wonderful patience and diligence. madam how is never idle for an instant. nothing is too great or too small for her; and she keeps her work before her eye in the same moment, and makes every separate bit of it help every other bit. she will keep the sun and stars in order, while she looks after poor old mrs. daddy- long-legs there and her eggs. she will spend thousands of years in building up a mountain, and thousands of years in grinding it down again; and then carefully polish every grain of sand which falls from that mountain, and put it in its right place, where it will be wanted thousands of years hence; and she will take just as much trouble about that one grain of sand as she did about the whole mountain. she will settle the exact place where mrs. daddy-long-legs shall lay her eggs, at the very same time that she is settling what shall happen hundreds of years hence in a stair millions of miles away. and i really believe that madam how knows her work so thoroughly, that the grain of sand which sticks now to your shoe, and the weight of mrs. daddy-long-legs' eggs at the bottom of her hole, will have an effect upon suns and stars ages after you and i are dead and gone. most patient indeed is madam how. she does not mind the least seeing her own work destroyed; she knows that it must be destroyed. there is a spell upon her, and a fate, that everything she makes she must unmake again: and yet, good and wise woman as she is, she never frets, nor tires, nor fudges her work, as we say at school. she takes just as much pains to make an acorn as to make a peach. she takes just as much pains about the acorn which the pig eats, as about the acorn which will grow into a tall oak, and help to build a great ship. she took just as much pains, again, about the acorn which you crushed under your foot just now, and which you fancy will never come to anything. madam how is wiser than that. she knows that it will come to something. she will find some use for it, as she finds a use for everything. that acorn which you crushed will turn into mould, and that mould will go to feed the roots of some plant, perhaps next year, if it lies where it is; or perhaps it will be washed into the brook, and then into the river, and go down to the sea, and will feed the roots of some plant in some new continent ages and ages hence: and so madam how will have her own again. you dropped your stick into the river yesterday, and it floated away. you were sorry, because it had cost you a great deal of trouble to cut it, and peel it, and carve a head and your name on it. madam how was not sorry, though she had taken a great deal more trouble with that stick than ever you had taken. she had been three years making that stick, out of many things, sunbeams among the rest. but when it fell into the river, madam how knew that she should not lose her sunbeams nor anything else: the stick would float down the river, and on into the sea; and there, when it got heavy with the salt water, it would sink, and lodge, and be buried, and perhaps ages hence turn into coal; and ages after that some one would dig it up and burn it, and then out would come, as bright warm flame, all the sunbeams that were stored away in that stick: and so madam how would have her own again. and if that should not be the fate of your stick, still something else will happen to it just as useful in the long run; for madam how never loses anything, but uses up all her scraps and odds and ends somehow, somewhere, somewhen, as is fit and proper for the housekeeper of the whole universe. indeed, madam how is so patient that some people fancy her stupid, and think that, because she does not fall into a passion every time you steal her sweets, or break her crockery, or disarrange her furniture, therefore she does not care. but i advise you as a little boy, and still more when you grow up to be a man, not to get that fancy into your head; for you will find that, however good-natured and patient madam how is in most matters, her keeping silence and not seeming to see you is no sign that she has forgotten. on the contrary, she bears a grudge (if one may so say, with all respect to her) longer than any one else does; because she will always have her own again. indeed, i sometimes think that if it were not for lady why, her mistress, she might bear some of her grudges for ever and ever. i have seen men ere now damage some of madam how's property when they were little boys, and be punished by her all their lives long, even though she had mended the broken pieces, or turned them to some other use. therefore i say to you, beware of madam how. she will teach you more kindly, patiently, and tenderly than any mother, if you want to learn her trade. but if, instead of learning her trade, you damage her materials and play with her tools, beware lest she has her own again out of you. some people think, again, that madam how is not only stupid, but ill-tempered and cruel; that she makes earthquakes and storms, and famine and pestilences, in a sort of blind passion, not caring where they go or whom they hurt; quite heedless of who is in the way, if she wants to do anything or go anywhere. now, that madam how can be very terrible there can be no doubt: but there is no doubt also that, if people choose to learn, she will teach them to get out of her way whenever she has business to do which is dangerous to them. but as for her being cruel and unjust, those may believe it who like. you, my dear boys and girls, need not believe it, if you will only trust to lady why; and be sure that why is the mistress and how the servant, now and for ever. that lady why is utterly good and kind i know full well; and i believe that, in her case too, the old proverb holds, "like mistress, like servant;" and that the more we know of madam how, the more we shall be content with her, and ready to submit to whatever she does: but not with that stupid resignation which some folks preach who do not believe in lady why--that is no resignation at all. that is merely saying-- "what can't be cured must be endured," like a donkey when he turns his tail to a hail-storm,--but the true resignation, the resignation which is fit for grown people and children alike, the resignation which is the beginning and the end of all wisdom and all religion, is to believe that lady why knows best, because she herself is perfectly good; and that as she is mistress over madam how, so she has a master over her, whose name--i say again--i leave you to guess. so now that i have taught you not to be afraid of madam how, we will go and watch her at her work; and if we do not understand anything we see, we will ask her questions. she will always show us one of her lesson books if we give her time. and if we have to wait some time for her answer, you need not fear catching cold, though it is november; for she keeps her lesson books scattered about in strange places, and we may have to walk up and down that hill more than once before we can make out how she makes the glen. well--how was the glen made? you shall guess it if you like, and i will guess too. you think, perhaps, that an earthquake opened it? my dear child, we must look before we guess. then, after we have looked a little, and got some grounds for guessing, then we may guess. and you have no ground for supposing there ever was an earthquake here strong enough to open that glen. there may have been one: but we must guess from what we do know, and not from what we do not. guess again. perhaps it was there always, from the beginning of the world? my dear child, you have no proof of that either. everything round you is changing in shape daily and hourly, as you will find out the longer you live; and therefore it is most reasonable to suppose that this glen has changed its shape, as everything else on earth has done. besides, i told you not that madam how had made the glen, but that she was making it, and as yet has only half finished. that is my first guess; and my next guess is that water is making the glen--water, and nothing else. you open your young eyes. and i do not blame you. i looked at this very glen for fifteen years before i made that guess; and i have looked at it some ten years since, to make sure that my guess held good. for man after all is very blind, my dear boy, and very stupid, and cannot see what lies under his own feet all day long; and if lady why, and he whom lady why obeys, were not very patient and gentle with mankind, they would have perished off the face of the earth long ago, simply from their own stupidity. i, at least, was very stupid in this case, for i had my head full of earthquakes, and convulsions of nature, and all sorts of prodigies which never happened to this glen; and so, while i was trying to find what was not there, i of course found nothing. but when i put them all out of my head, and began to look for what was there, i found it at once; and lo and behold! i had seen it a thousand times before, and yet never learnt anything from it, like a stupid man as i was; though what i learnt you may learn as easily as i did. and what did i find? the pond at the bottom of the glen. you know that pond, of course? you don't need to go there? very well. then if you do, do not you know also that the pond is always filling up with sand and mud; and that though we clean it out every three or four years, it always fills again? now where does that sand and mud come from? down that stream, of course, which runs out of this bog. you see it coming down every time there is a flood, and the stream fouls. very well. then, said madam how to me, as soon as i recollected that, "don't you see, you stupid man, that the stream has made the glen, and the earth which runs down the stream was all once part of the hill on which you stand." i confess i was very much ashamed of myself when she said that. for that is the history of the whole mystery. madam how is digging away with her soft spade, water. she has a harder spade, or rather plough, the strongest and most terrible of all ploughs; but that, i am glad to say, she has laid by in england here. water? but water is too simple a thing to have dug out all this great glen. my dear child, the most wonderful part of madam how's work is, that she does such great things and so many different things, with one and the same tool, which looks to you so simple, though it really is not so. water, for instance, is not a simple thing, but most complicated; and we might spend hours in talking about water, without having come to the end of its wonders. still madam how is a great economist, and never wastes her materials. she is like the sailor who boasted (only she never boasts) that, if he had but a long life and a strong knife, he would build st. paul's cathedral before he was done. and madam how has a very long life, and plenty of time; and one of the strongest of all her tools is water. now if you will stoop down and look into the heather, i will show you how she is digging out the glen with this very mist which is hanging about our feet. at least, so i guess. for see how the mist clings to the points of the heather leaves, and makes drops. if the hot sun came out the drops would dry, and they would vanish into the air in light warm steam. but now that it is dark and cold they drip, or run down the heather-stems, to the ground. and whither do they go then? whither will the water go,--hundreds of gallons of it perhaps,--which has dripped and run through the heather in this single day? it will sink into the ground, you know. and then what will become of it? madam how will use it as an underground spade, just as she uses the rain (at least, when it rains too hard, and therefore the rain runs off the moor instead of sinking into it) as a spade above ground. now come to the edge of the glen, and i will show you the mist that fell yesterday, perhaps, coming out of the ground again, and hard at work. you know of what an odd, and indeed of what a pretty form all these glens are. how the flat moor ends suddenly in a steep rounded bank, almost like the crest of a wave--ready like a wave-crest to fall over, and as you know, falling over sometimes, bit by bit, where the soil is bare. oh, yes; you are very fond of those banks. it is "awfully jolly," as you say, scrambling up and down them, in the deep heath and fern; besides, there are plenty of rabbit-holes there, because they are all sand; while there are no rabbit-holes on the flat above, because it is all gravel. yes; you know all about it: but you know, too, that you must not go too far down these banks, much less roll down them, because there is almost certain to be a bog at the bottom, lying upon a gentle slope; and there you get wet through. all round these hills, from here to aldershot in one direction, and from here to windsor in another, you see the same shaped glens; the wave-crest along their top, and at the foot of the crest a line of springs which run out over the slopes, or well up through them in deep sand-galls, as you call them--shaking quagmires which are sometimes deep enough to swallow up a horse, and which you love to dance upon in summer time. now the water of all these springs is nothing but the rain, and mist, and dew, which has sunk down first through the peaty soil, and then through the gravel and sand, and there has stopped. and why? because under the gravel (about which i will tell you a strange story one day) and under the sand, which is what the geologists call the upper bagshot sand, there is an entirely different set of beds, which geologists call the bracklesham beds, from a place near the new forest; and in those beds there is a vein of clay, and through that clay the water cannot get, as you have seen yourself when we dug it out in the field below to puddle the pond-head; and very good fun you thought it, and a very pretty mess you made of yourself. well: because the water cannot get though this clay, and must go somewhere, it runs out continually along the top of the clay, and as it runs undermines the bank, and brings down sand and gravel continually for the next shower to wash into the stream below. now think for one moment how wonderful it is that the shape of these glens, of which you are so fond, was settled by the particular order in which madam how laid down the gravel and sand and mud at the bottom of the sea, ages and ages ago. this is what i told you, that the least thing that madam how does to-day may take effect hundreds and thousands of years hence. but i must tell you i think there was a time when this glen was of a very different shape from what it is now; and i dare say, according to your notions, of a much prettier shape. it was once just like one of those chines which we used to see at bournemouth. you recollect them? how there was a narrow gap in the cliff of striped sands and gravels; and out of the mouth of that gap, only a few feet across, there poured down a great slope of mud and sand the shape of half a bun, some wet and some dry, up which we used to scramble and get into the chine, and call the chine what it was in the truest sense, fairyland. you recollect how it was all eaten out into mountain ranges, pinnacles, steep cliffs of white, and yellow, and pink, standing up against the clear blue sky; till we agreed that, putting aside the difference of size, they were as beautiful and grand as any alps we had ever seen in pictures. and how we saw (for there could be no mistake about it there) that the chine was being hollowed out by the springs which broke out high up the cliff, and by the rain which wore the sand into furrowed pinnacles and peaks. you recollect the beautiful place, and how, when we looked back down it we saw between the miniature mountain walls the bright blue sea, and heard it murmur on the sands outside. so i verily believe we might have done, if we had stood somewhere at the bottom of this glen thousands of years ago. we should have seen the sea in front of us; or rather, an arm of the sea; for finchampstead ridges opposite, instead of being covered with farms, and woodlands, and purple heath above, would have been steep cliffs of sand and clay, just like those you see at bournemouth now; and--what would have spoilt somewhat the beauty of the sight--along the shores there would have floated, at least in winter, great blocks and floes of ice, such as you might have seen in the tideway at king's lynn the winter before last, growling and crashing, grubbing and ploughing the sand, and the gravel, and the mud, and sweeping them away into seas towards the north, which are now all fruitful land. that may seem to you like a dream: yet it is true; and some day, when we have another talk with madam how, i will show even a child like you that it was true. but what could change a beautiful chine like that at bournemouth into a wide sloping glen like this of bracknell's bottom, with a wood like coombs', many acres large, in the middle of it? well now, think. it is a capital plan for finding out madam how's secrets, to see what she might do in one place, and explain by it what she has done in another. suppose now, madam how had orders to lift up the whole coast of bournemouth only twenty or even ten feet higher out of the sea than it is now. she could do that easily enough, for she has been doing so on the coast of south america for ages; she has been doing so this very summer in what hasty people would call a hasty, and violent, and ruthless way; though i shall not say so, for i believe that lady why knows best. she is doing so now steadily on the west coast of norway, which is rising quietly--all that vast range of mountain wall and iron-bound cliff--at the rate of some four feet in a hundred years, without making the least noise or confusion, or even causing an extra ripple on the sea; so light and gentle, when she will, can madam how's strong finger be. now, if the mouth of that chine at bournemouth was lifted twenty feet out of the sea, one thing would happen,--that the high tide would not come up any longer, and wash away the cake of dirt at the entrance, as we saw it do so often. but if the mud stopped there, the mud behind it would come down more slowly, and lodge inside more and more, till the chine was half filled-up, and only the upper part of the cliffs continue to be eaten away, above the level where the springs ran out. so gradually the chine, instead of being deep and narrow, would become broad and shallow; and instead of hollowing itself rapidly after every shower of rain, as you saw the chine at bournemouth doing, would hollow itself out slowly, as this glen is doing now. and one thing more would happen,--when the sea ceased to gnaw at the foot of the cliffs outside, and to carry away every stone and grain of sand which fell from them, the cliffs would very soon cease to be cliffs; the rain and the frost would still crumble them down, but the dirt that fell would lie at their feet, and gradually make a slope of dry land, far out where the shallow sea had been; and their tops, instead of being steep as now, would become smooth and rounded; and so at last, instead of two sharp walls of cliff at the chine's mouth, you might have--just what you have here at the mouth of this glen,--our mount and the warren hill,--long slopes with sheets of drifted gravel and sand at their feet, stretching down into what was once an icy sea, and is now the vale of blackwater. and this i really believe madam how has done simply by lifting hartford bridge flat a few more feet out of the sea, and leaving the rest to her trusty tool, the water in the sky. that is my guess: and i think it is a good guess, because i have asked madam how a hundred different questions about it in the last ten years, and she always answered them in the same way, saying, "water, water, you stupid man." but i do not want you merely to depend on what i say. if you want to understand madam how, you must ask her questions yourself, and make up your mind yourself like a man, instead of taking things at hearsay or second-hand, like the vulgar. mind, by "the vulgar" i do not mean poor people: i mean ignorant and uneducated people, who do not use their brains rightly, though they may be fine ladies, kings, or popes. the bible says, "prove all things: hold fast that which is good." so do you prove my guess, and if it proves good, hold it fast. and how can i do that? first, by direct experiment, as it is called. in plain english--go home and make a little hartford bridge flat in the stable-yard; and then ask mrs. how if she will not make a glen in it like this glen here. we will go home and try that. we will make a great flat cake of clay, and put upon it a cap of sand; and then we will rain upon it out of a watering- pot; and see if mrs. how does not begin soon to make a glen in the side of the heap, just like those on hartford bridge flat. i believe she will; and certainly, if she does, it will be a fresh proof that my guess is right. and then we will see whether water will not make glens of a different shape than these, if it run over soils of a different kind. we will make a hartford bridge flat turned upside down--a cake of sand with a cap of clay on the top; and we will rain on that out of our watering- pot, and see what sort of glens we make then. i can guess what they will be like, because i have seen them--steep overhanging cliffs, with very narrow gullies down them: but you shall try for yourself, and make up your mind whether you think me right or wrong. meanwhile, remember that those gullies too will have been made by water. and there is another way of "verifying my theory," as it is called; in plain english, seeing if my guess holds good; that is, to look at other valleys--not merely the valleys round here, but valleys in clay, in chalk, in limestone, in the hard slate rock such as you saw in devonshire--and see whether my guess does not hold good about them too; whether all of them, deep or shallow, broad or narrow, rock or earth, may not have been all hollowed out by running water. i am sure if you would do this you would find something to amuse you, and something to instruct you, whenever you wish. i know that i do. to me the longest railroad journey, instead of being stupid, is like continually turning over the leaves of a wonderful book, or looking at wonderful pictures of old worlds which were made and unmade thousands of years ago. for i keep looking, not only at the railway cuttings, where the bones of the old worlds are laid bare, but at the surface of the ground; at the plains and downs, banks and knolls, hills and mountains; and continually asking mrs. how what gave them each its shape: and i will soon teach you to do the same. when you do, i tell you fairly her answer will be in almost every case, "running water." either water running when soft, as it usually is; or water running when it is hard--in plain words, moving ice. about that moving ice, which is mrs. how's stronger spade, i will tell you some other time; and show you, too, the marks of it in every gravel pit about here. but now, i see, you want to ask a question; and what is it? do i mean to say that water has made great valleys, such as you have seen paintings and photographs of,--valleys thousands of feet deep, among mountains thousands of feet high? yes, i do. but, as i said before, i do not like you to take my word upon trust. when you are older you shall go to the mountains, and you shall judge for yourself. still, i must say that i never saw a valley, however deep, or a cliff, however high, which had not been scooped out by water; and that even the mountain-tops which stand up miles aloft in jagged peaks and pinnacles against the sky were cut out at first, and are being cut and sharpened still, by little else save water, soft and hard; that is, by rain, frost, and ice. water, and nothing else, has sawn out such a chasm as that through which the ships run up to bristol, between leigh wood and st. vincent's rocks. water, and nothing else, has shaped those peaks of the matterhorn, or the weisshorn, or the pic du midi of the pyrenees, of which you have seen sketches and photographs. just so water might saw out hartford bridge flat, if it had time enough, into a labyrinth of valleys, and hills, and peaks standing alone; as it has done already by ambarrow, and edgbarrow, and the folly hill on the other side of the vale. i see you are astonished at the notion that water can make alps. but it was just because i knew you would be astonished at madam how's doing so great a thing with so simple a tool, that i began by showing you how she was doing the same thing in a small way here upon these flats. for the safest way to learn madam how's methods is to watch her at work in little corners at commonplace business, which will not astonish or frighten us, nor put huge hasty guesses and dreams into our heads. sir isaac newton, some will tell you, found out the great law of gravitation, which holds true of all the suns and stars in heaven, by watching an apple fall: and even if he did not find it out so, he found it out, we know, by careful thinking over the plain and commonplace fact, that things have weight. so do you be humble and patient, and watch madam how at work on little things. for that is the way to see her at work upon all space and time. what? you have a question more to ask? oh! i talked about madam how lifting up hartford bridge flat. how could she do that? my dear child, that is a long story, and i must tell it you some other time. meanwhile, did you ever see the lid of a kettle rise up and shake when the water inside boiled? of course; and of course, too, remember that madam how must have done it. then think over between this and our next talk, what that can possibly have to do with her lifting up hartford bridge flat. but you have been longing, perhaps, all this time to hear more about lady why, and why she set madam how to make bracknell's bottom. my dear child, the only answer i dare give to that is: whatever other purposes she may have made it for, she made it at least for this--that you and i should come to it this day, and look at, and talk over it, and become thereby wiser and more earnest, and we will hope more humble and better people. whatever else lady why may wish or not wish, this she wishes always, to make all men wise and all men good. for what is written of her whom, as in a parable, i have called lady why? "the lord possessed me in the beginning of his way, before his works of old. "i was set up from everlasting, from the beginning, or ever the earth was. "when there were no depths, i was brought forth; when there were no fountains abounding with water. "before the mountains were settled, before the hills was i brought forth: "while as yet he had not made the earth, nor the fields, nor the highest part of the dust of the world. "when he prepared the heavens, i was there: when he set a compass upon the face of the depth: "when he established the clouds above: when he strengthened the fountains of the deep: "when he gave to the sea his decree, that the waters should not pass his commandment: when he appointed the foundations of the earth: "then i was by him, as one brought up with him: and i was daily his delight, rejoicing always before him: "rejoicing in the habitable part of his earth; and my delights were with the sons of men. "now therefore hearken unto me, o ye children: for blessed are they that keep my ways." that we can say, for it has been said for us already. but beyond that we can say, and need say, very little. we were not there, as we read in the book of job, when god laid the foundations of the earth. "we see," says st. paul, "as in a glass darkly, and only know in part." "for who," he asks again, "has known the mind of the lord, or who hath been his counsellor? . . . for of him, and through him, and to him, are all things: to whom be glory for ever and ever. amen." therefore we must not rashly say, this or that is why a thing has happened; nor invent what are called "final causes," which are not lady why herself, but only our little notions of what lady why has done, or rather what we should have done if we had been in her place. it is not, indeed, by thinking that we shall find out anything about lady why. she speaks not to our eyes or to our brains, like madam how, but to that inner part of us which we call our hearts and spirits, and which will endure when eyes and brain are turned again to dust. if your heart be pure and sober, gentle and truthful, then lady why speaks to you without words, and tells you things which madam how and all her pupils, the men of science, can never tell. when you lie, it may be, on a painful sick-bed, but with your mother's hand in yours; when you sit by her, looking up into her loving eyes; when you gaze out towards the setting sun, and fancy golden capes and islands in the clouds, and seas and lakes in the blue sky, and the infinite rest and peace of the far west sends rest and peace into your young heart, till you sit silent and happy, you know not why; when sweet music fills your heart with noble and tender instincts which need no thoughts or words; ay, even when you watch the raging thunderstorm, and feel it to be, in spite of its great awfulness, so beautiful that you cannot turn your eyes away: at such times as these lady why is speaking to your soul of souls, and saying, "my child, this world is a new place, and strange, and often terrible: but be not afraid. all will come right at last. rest will conquer restlessness; faith will conquer fear; order will conquer disorder; health will conquer sickness; joy will conquer sorrow; pleasure will conquer pain; life will conquer death; right will conquer wrong. all will be well at last. keep your soul and body pure, humble, busy, pious--in one word, be good: and ere you die, or after you die, you may have some glimpse of me, the everlasting why: and hear with the ears, not of your body but of your spirit, men and all rational beings, plants and animals, ay, the very stones beneath your feet, the clouds above your head, the planets and the suns away in farthest space, singing eternally, "'thou art worthy, o lord, to receive glory and honour and power, for thou hast created all things, and for thy pleasure they are and were created."' chapter ii--earthquakes so? you have been looking at that beautiful drawing of the ruin of arica in the _illustrated london news_: and it has puzzled you and made you sad. you want to know why god killed all those people--mothers among them, too, and little children? alas, my dear child! who am i that i should answer you that? have you done wrong in asking me? no, my dear child; no. you have asked me because you are a human being and a child of god, and not merely a cleverer sort of animal, an ape who can read and write and cast accounts. therefore it is that you cannot be content, and ought not to be content, with asking how things happen, but must go on to ask why. you cannot be content with knowing the causes of things; and if you knew all the natural science that ever was or ever will be known to men, that would not satisfy you; for it would only tell you the _causes_ of things, while your souls want to know the _reasons_ of things besides; and though i may not be able to tell you the reasons of things, or show you aught but a tiny glimpse here and there of that which i called the other day the glory of lady why, yet i believe that somehow, somewhen, somewhere, you will learn something of the reason of things. for that thirst to know _why_ was put into the hearts of little children by god himself; and i believe that god would never have given them that thirst if he had not meant to satisfy it. there--you do not understand me. i trust that you will understand me some day. meanwhile, i think--i only say i _think_--you know i told you how humble we must be whenever we speak of lady why--that we may guess at something like a good reason for the terrible earthquakes in south america. i do not wish to be hard upon poor people in great affliction: but i cannot help thinking that they have been doing for hundreds of years past something very like what the bible calls "tempting god"--staking their property and their lives upon the chances of no earthquakes coming, while they ought to have known that an earthquake might come any day. they have fulfilled (and little thought i that it would be fulfilled so soon) the parable that i told you once, of the nation of the do-as-you-likes, who lived careless and happy at the foot of the burning mountain, and would not be warned by the smoke that came out of the top, or by the slag and cinders which lay all about them; till the mountain blew up, and destroyed them miserably. then i think that they ought to have expected an earthquake. well--it is not for us to judge any one, especially if they live in a part of the world in which we have not been ourselves. but i think that we know, and that they ought to have known, enough about earthquakes to have been more prudent than they have been for many a year. at least we will hope that, though they would not learn their lesson till this year, they will learn it now, and will listen to the message which i think madam how has brought them, spoken in a voice of thunder, and written in letters of flame. and what is that? my dear child, if the landlord of our house was in the habit of pulling the roof down upon our heads, and putting gunpowder under the foundations to blow us up, do you not think we should know what he meant, even though he never spoke a word? he would be very wrong in behaving so, of course: but one thing would be certain,--that he did not intend us to live in his house any longer if he could help it; and was giving us, in a very rough fashion, notice to quit. and so it seems to me that these poor spanish americans have received from the landlord of all landlords, who can do no wrong, such a notice to quit as perhaps no people ever had before; which says to them in unmistakable words, "you must leave this country: or perish." and i believe that that message, like all lady why's messages, is at heart a merciful and loving one; that if these spaniards would leave the western coast of peru, and cross the andes into the green forests of the eastern side of their own land, they might not only live free from earthquakes, but (if they would only be good and industrious) become a great, rich, and happy nation, instead of the idle, and useless, and i am afraid not over good, people which they have been. for in that eastern part of their own land god's gifts are waiting for them, in a paradise such as i can neither describe nor you conceive;--precious woods, fruits, drugs, and what not--boundless wealth, in one word--waiting for them to send it all down the waters of the mighty river amazon, enriching us here in the old world, and enriching themselves there in the new. if they would only go and use these gifts of god, instead of neglecting them as they have been doing for now three hundred years, they would be a blessing to the earth, instead of being--that which they have been. god grant, my dear child, that these poor people may take the warning that has been sent to them; "the voice of god revealed in facts," as the great lord bacon would have called it, and see not only that god has bidden them leave the place where they are now, but has prepared for them, in their own land, a home a thousand times better than that in which they now live. but you ask, how ought they to have known that an earthquake would come? well, to make you understand that, we must talk a little about earthquakes, and what makes them; and in order to find out that, let us try the very simplest cause of which we can think. that is the wise and scientific plan. now, whatever makes these earthquakes must be enormously strong; that is certain. and what is the strongest thing you know of in the world? think . . . gunpowder? well, gunpowder is strong sometimes: but not always. you may carry it in a flask, or in your hand, and then it is weak enough. it only becomes strong by being turned into gas and steam. but steam is always strong. and if you look at a railway engine, still more if you had ever seen--which god forbid you should--a boiler explosion, you would agree with me, that the strongest thing we know of in the world is steam. now i think that we can explain almost, if not quite, all that we know about earthquakes, if we believe that on the whole they are caused by steam and other gases expanding, that is, spreading out, with wonderful quickness and strength. of course there must be something to make them expand, and that is _heat_. but we will not talk of that yet. now do you remember that riddle which i put to you the other day?--"what had the rattling of the lid of the kettle to do with hartford bridge flat being lifted out of the ancient sea?" the answer to the riddle, i believe, is--steam has done both. the lid of the kettle rattles, because the expanding steam escapes in little jets, and so causes a _lid-quake_. now suppose that there was steam under the earth trying to escape, and the earth in one place was loose and yet hard, as the lid of the kettle is loose and yet hard, with cracks in it, it may be, like the crack between the edge of the lid and the edge of the kettle itself: might not the steam try to escape through the cracks, and rattle the surface of the earth, and so cause an _earthquake_? so the steam would escape generally easily, and would only make a passing rattle, like the earthquake of which the famous jester charles selwyn said that it was quite a young one, so tame that you might have stroked it; like that which i myself once felt in the pyrenees, which gave me very solemn thoughts after a while, though at first i did nothing but laugh at it; and i will tell you why. i was travelling in the pyrenees; and i came one evening to the loveliest spot--a glen, or rather a vast crack in the mountains, so narrow that there was no room for anything at the bottom of it, save a torrent roaring between walls of polished rock. high above the torrent the road was cut out among the cliffs, and above the road rose more cliffs, with great black cavern mouths, hundreds of feet above our heads, out of each of which poured in foaming waterfalls streams large enough to turn a mill, and above them mountains piled on mountains, all covered with woods of box, which smelt rich and hot and musky in the warm spring air. among the box-trees and fallen boulders grew hepaticas, blue and white and red, such as you see in the garden; and little stars of gentian, more azure than the azure sky. but out of the box-woods above rose giant silver firs, clothing the cliffs and glens with tall black spires, till they stood out at last in a jagged saw-edge against the purple evening sky, along the mountain ranges, thousands of feet aloft; and beyond them again, at the head of the valley, rose vast cones of virgin snow, miles away in reality, but looking so brilliant and so near that one fancied at the first moment that one could have touched them with one's hand. snow- white they stood, the glorious things, seven thousand feet into the air; and i watched their beautiful white sides turn rose-colour in the evening sun, and when he set, fade into dull cold gray, till the bright moon came out to light them up once more. when i was tired of wondering and admiring, i went into bed; and there i had a dream--such a dream as alice had when she went into wonderland--such a dream as i dare say you may have had ere now. some noise or stir puts into your fancy as you sleep a whole long dream to account for it; and yet that dream, which seems to you to be hours long, has not taken up a second of time; for the very same noise which begins the dream, wakes you at the end of it: and so it was with me. i dreamed that some english people had come into the hotel where i was, and were sleeping in the room underneath me; and that they had quarrelled and fought, and broke their bed down with a tremendous crash, and that i must get up, and stop the fight; and at that moment i woke and heard coming up the valley from the north such a roar as i never heard before or since; as if a hundred railway trains were rolling underground; and just as it passed under my bed there was a tremendous thump, and i jumped out of bed quicker than i ever did in my life, and heard the roaring sound die away as it rolled up the valley towards the peaks of snow. still i had in my head this notion of the englishmen fighting in the room below. but then i recollected that no englishmen had come in the night before, and that i had been in the room below, and that there was no bed in it. then i opened my window--a woman screamed, a dog barked, some cocks and hens cackled in a very disturbed humour, and then i could hear nothing but the roaring of the torrent a hundred feet below. and then it flashed across me what all the noise was about; and i burst out laughing and said "it is only an earthquake," and went to bed next morning i inquired whether any one had heard a noise. no, nobody had heard anything. and the driver who had brought me up the valley only winked, but did not choose to speak. at last at breakfast i asked the pretty little maid who waited what was the meaning of the noise i heard in the night, and she answered, to my intense amusement, "ah! bah! ce n'etait qu'un tremblement de terre; il y en a ici toutes les six semaines." now the secret was out. the little maid, i found, came from the lowland far away, and did not mind telling the truth: but the good people of the place were afraid to let out that they had earthquakes every six weeks, for fear of frightening visitors away: and because they were really very good people, and very kind to me, i shall not tell you what the name of the place is. of course after that i could do no less than ask madam how, very civilly, how she made earthquakes in that particular place, hundreds of miles away from any burning mountain? and this was the answer i _thought_ she gave, though i am not so conceited as to say i am sure. as i had come up the valley i had seen that the cliffs were all beautiful gray limestone marble; but just at this place they were replaced by granite, such as you may see in london bridge or at aberdeen. i do not mean that the limestone changed to granite, but that the granite had risen up out of the bottom of the valley, and had carried the limestone (i suppose) up on its back hundreds of feet into the air. those caves with the waterfalls pouring from their mouths were all on one level, at the top of the granite, and the bottom of the limestone. that was to be expected; for, as i will explain to you some day, water can make caves easily in limestone: but never, i think, in granite. but i knew that besides these cold springs which came out of the caves, there were hot springs also, full of curious chemical salts, just below the very house where i was in. and when i went to look at them, i found that they came out of the rock just where the limestone and the granite joined. "ah," i said, "now i think i have madam how's answer. the lid of one of her great steam boilers is rather shaky and cracked just here, because the granite has broken and torn the limestone as it lifted it up; and here is the hot water out of the boiler actually oozing out of the crack; and the earthquake i heard last night was simply the steam rumbling and thumping inside, and trying to get out." and then, my dear child, i fell into a more serious mood. i said to myself, "if that stream had been a little, only a little stronger, or if the rock above it had been only a little weaker, it would have been no laughing matter then; the village might have been shaken to the ground; the rocks hurled into the torrent; jets of steam and of hot water, mixed, it may be, with deadly gases, have roared out of the riven ground; that might have happened here, in short, which has happened and happens still in a hundred places in the world, whenever the rocks are too weak to stand the pressure of the steam below, and the solid earth bursts as an engine boiler bursts when the steam within it is too strong." and when those thoughts came into my mind, i was in no humour to jest any more about "young earthquakes," or "madam how's boilers;" but rather to say with the wise man of old, "it is of the lord's mercies that we are not consumed." most strange, most terrible also, are the tricks which this underground steam plays. it will make the ground, which seems to us so hard and firm, roll and rock in waves, till people are sea-sick, as on board a ship; and that rocking motion (which is the most common) will often, when it is but slight, set the bells ringing in the steeples, or make the furniture, and things on shelves, jump about quaintly enough. it will make trees bend to and fro, as if a wind was blowing through them; open doors suddenly, and shut them again with a slam; make the timbers of the floors and roofs creak, as they do in a ship at sea; or give men such frights as one of the dock-keepers at liverpool got in the earthquake in , when his watchbox rocked so, that he thought some one was going to pitch him over into the dock. but these are only little hints and warnings of what it can do. when it is strong enough, it will rock down houses and churches into heaps of ruins, or, if it leaves them standing, crack them from top to bottom, so that they must be pulled down and rebuilt. you saw those pictures of the ruins of arica, about which our talk began; and from them you can guess well enough for yourself what a town looks like which has been ruined by an earthquake. of the misery and the horror which follow such a ruin i will not talk to you, nor darken your young spirit with sad thoughts which grown people must face, and ought to face. but the strangeness of some of the tricks which the earthquake shocks play is hardly to be explained, even by scientific men. sometimes, it would seem, the force runs round, making the solid ground eddy, as water eddies in a brook. for it will make straight rows of trees crooked; it will twist whole walls round--or rather the ground on which the walls stand--without throwing them down; it will shift the stones of a pillar one on the other sideways, as if a giant had been trying to spin it like a teetotum, and so screwed it half in pieces. there is a story told by a wise man, who saw the place himself, of the whole furniture of one house being hurled away by an earthquake, and buried under the ruins of another house; and of things carried hundreds of yards off, so that the neighbours went to law to settle who was the true owner of them. sometimes, again, the shock seems to come neither horizontally in waves, nor circularly in eddies, but vertically, that is, straight up from below; and then things--and people, alas! sometimes--are thrown up off the earth high into the air, just as things spring up off the table if you strike it smartly enough underneath. by that same law (for there is a law for every sort of motion) it is that the earthquake shock sometimes hurls great rocks off a cliff into the valley below. the shock runs through the mountain till it comes to the cliff at the end of it; and then the face of the cliff, if it be at all loose, flies off into the air. you may see the very same thing happen, if you will put marbles or billiard-balls in a row touching each other, and strike the one nearest you smartly in the line of the row. all the balls stand still, except the last one, and that flies off. the shock, like the earthquake shock, has run through them all; but only the end one, which had nothing beyond it but soft air, has been moved; and when you grow old, and learn mathematics, you will know the law of motion according to which that happens, and learn to apply what the billiard-balls have taught you, to explain the wonders of an earthquake. for in this case, as in so many more, you must watch madam how at work on little and common things, to find out how she works in great and rare ones. that is why solomon says that "a fool's eyes are in the ends of the earth," because he is always looking out for strange things which he has not seen, and which he could not understand if he saw; instead of looking at the petty commonplace matters which are about his feet all day long, and getting from them sound knowledge, and the art of getting more sound knowledge still. another terrible destruction which the earthquake brings, when it is close to the seaside, is the wash of a great sea wave, such as swept in last year upon the island of st. thomas, in the west indies; such as swept in upon the coast of peru this year. the sea moans, and sinks back, leaving the shore dry; and then comes in from the offing a mighty wall of water, as high as, or higher than, many a tall house; sweeps far inland, washing away quays and houses, and carrying great ships in with it; and then sweeps back again, leaving the ships high and dry, as ships were left in peru this year. now, how is that wave made? let us think. perhaps in many ways. but two of them i will tell you as simply as i can, because they seem the most likely, and probably the most common. suppose, as the earthquake shock ran on, making the earth under the sea heave and fall in long earth-waves, the sea-bottom sank down. then the water on it would sink down too, and leave the shore dry; till the sea- bottom rose again, and hurled the water up again against the land. this is one way of explaining it, and it may be true. for certain it is, that earthquakes do move the bottom of the sea; and certain, too, that they move the water of the sea also, and with tremendous force. for ships at sea during an earthquake feel such a blow from it (though it does them no harm) that the sailors often rush upon deck fancying that they have struck upon a rock; and the force which could give a ship, floating in water, such a blow as that, would be strong enough to hurl thousands of tons of water up the beach, and on to the land. but there is another way of accounting for this great sea wave, which i fancy comes true sometimes. suppose you put an empty india-rubber ball into water, and then blow into it through a pipe. of course, you know, as the ball filled, the upper side of it would rise out of the water. now, suppose there were a party of little ants moving about upon that ball, and fancying it a great island, or perhaps the whole world--what would they think of the ball's filling and growing bigger? if they could see the sides of the basin or tub in which the ball was, and were sure that they did not move, then they would soon judge by them that they themselves were moving, and that the ball was rising out of the water. but if the ants were so short-sighted that they could not see the sides of the basin, they would be apt to make a mistake, because they would then be like men on an island out of sight of any other land. then it would be impossible further to tell whether they were moving up, or whether the water was moving down; whether their ball was rising out of the water, or the water was sinking away from the ball. they would probably say, "the water is sinking and leaving the ball dry." do you understand that? then think what would happen if you pricked a hole in the ball. the air inside would come hissing out, and the ball would sink again into the water. but the ants would probably fancy the very opposite. their little heads would be full of the notion that the ball was solid and could not move, just as our heads are full of the notion that the earth is solid and cannot move; and they would say, "ah! here is the water rising again." just so, i believe, when the sea seems to ebb away during the earthquake, the land is really being raised out of the sea, hundreds of miles of coast, perhaps, or a whole island, at once, by the force of the steam and gas imprisoned under the ground. that steam stretches and strains the solid rocks below, till they can bear no more, and snap, and crack, with frightful roar and clang; then out of holes and chasms in the ground rush steam, gases--often foul and poisonous ones--hot water, mud, flame, strange stones--all signs that the great boiler down below has burst at last. then the strain is eased. the earth sinks together again, as the ball did when it was pricked; and sinks lower, perhaps, than it was before: and back rushes the sea, which the earth had thrust away while it rose, and sweeps in, destroying all before it. of course, there is a great deal more to be said about all this: but i have no time to tell you now. you will read it, i hope, for yourselves when you grow up, in the writings of far wiser men than i. or perhaps you may feel for yourselves in foreign lands the actual shock of a great earthquake, or see its work fresh done around you. and if ever that happens, and you be preserved during the danger, you will learn for yourself, i trust, more about earthquakes than i can teach you, if you will only bear in mind the simple general rules for understanding the "how" of them which i have given you here. but you do not seem satisfied yet? what is it that you want to know? oh! there was an earthquake here in england the other night, while you were asleep; and that seems to you too near to be pleasant. will there ever be earthquakes in england which will throw houses down, and bury people in the ruins? my dear child, i think you may set your heart at rest upon that point. as far as the history of england goes back, and that is more than a thousand years, there is no account of any earthquake which has done any serious damage, or killed, i believe, a single human being. the little earthquakes which are sometimes felt in england run generally up one line of country, from devonshire through wales, and up the severn valley into cheshire and lancashire, and the south-west of scotland; and they are felt more smartly there, i believe, because the rocks are harder there than here, and more tossed about by earthquakes which happened ages and ages ago, long before man lived on the earth. i will show you the work of these earthquakes some day, in the tilting and twisting of the layers of rock, and in the cracks (faults, as they are called) which run through them in different directions. i showed you some once, if you recollect, in the chalk cliff at ramsgate--two set of cracks, sloping opposite ways, which i told you were made by two separate sets of earthquakes, long, long ago, perhaps while the chalk was still at the bottom of a deep sea. but even in the rocky parts of england the earthquake-force seems to have all but died out. perhaps the crust of the earth has become too thick and solid there to be much shaken by the gases and steam below. in this eastern part of england, meanwhile, there is but little chance that an earthquake will ever do much harm, because the ground here, for thousands of feet down, is not hard and rocky, but soft--sands, clays, chalk, and sands again; clays, soft limestones, and clays again--which all act as buffers to deaden the earthquake shocks, and deaden too the earthquake noise. and how? put your ear to one end of a soft bolster, and let some one hit the other end. you will hear hardly any noise, and will not feel the blow at all. put your ear to one end of a hard piece of wood, and let some one hit the other. you will hear a smart tap; and perhaps feel a smart tap, too. when you are older, and learn the laws of sound, and of motion among the particles of bodies, you will know why. meanwhile you may comfort yourself with the thought that madam how has (doubtless by command of lady why) prepared a safe soft bed for this good people of britain--not that they may lie and sleep on it, but work and till, plant and build and manufacture, and thrive in peace and comfort, we will trust and pray, for many a hundred years to come. all that the steam inside the earth is likely to do to us, is to raise parts of this island (as hartford bridge flats were raised, ages ago, out of the old icy sea) so slowly, probably, that no man can tell whether they are rising or not. or again, the steam- power may be even now dying out under our island, and letting parts of it sink slowly into the sea, as some wise friends of mine think that the fens in norfolk and cambridgeshire are sinking now. i have shown you where that kind of work has gone on in norfolk; how the brow of sandringham hill was once a sea-cliff, and dersingham bog at its foot a shallow sea; and therefore that the land has risen there. how, again, at hunstanton station there is a beach of sea-shells twenty feet above high- water mark, showing that the land has risen there likewise. and how, farther north again, at brancaster, there are forests of oak, and fir, and alder, with their roots still in the soil, far below high-water mark, and only uncovered at low tide; which is a plain sign that there the land has sunk. you surely recollect the sunken forest at brancaster, and the beautiful shells we picked up in its gullies, and the millions of live pholases boring into the clay and peat which once was firm dry land, fed over by giant oxen, and giant stags likewise, and perhaps by the mammoth himself, the great woolly elephant whose teeth the fishermen dredge up in the sea outside? you recollect that? then remember that as that norfolk shore has changed, so slowly but surely is the whole world changing around us. hartford bridge flat here, for instance, how has it changed! ages ago it was the gravelly bottom of a sea. then the steam-power underground raised it up slowly, through long ages, till it became dry land. and ages hence, perhaps, it will have become a sea-bottom once more. washed slowly by the rain, or sunk by the dying out of the steam- power underground, it will go down again to the place from whence it came. seas will roll where we stand now, and new lands will rise where seas now roll. for all things on this earth, from the tiniest flower to the tallest mountain, change and change all day long. every atom of matter moves perpetually; and nothing "continues in one stay." the solid- seeming earth on which you stand is but a heaving bubble, bursting ever and anon in this place and in that. only above all, and through all, and with all, is one who does not move nor change, but is the same yesterday, to-day, and for ever. and on him, my child, and not on this bubble of an earth, do you and i, and all mankind, depend. but i have not yet told you why the peruvians ought to have expected an earthquake. true. i will tell you another time. chapter iii--volcanos you want to know why the spaniards in peru and ecuador should have expected an earthquake. because they had had so many already. the shaking of the ground in their country had gone on perpetually, till they had almost ceased to care about it, always hoping that no very heavy shock would come; and being, now and then, terribly mistaken. for instance, in the province of quito, in the year , from thirty to forty thousand people were killed at once by an earthquake. one would have thought that warning enough: but the warning was not taken: and now, this very year, thousands more have been killed in the very same country, in the very same way. they might have expected as much. for their towns are built, most of them, close to volcanos--some of the highest and most terrible in the world. and wherever there are volcanos there will be earthquakes. you may have earthquakes without volcanos, now and then; but volcanos without earthquakes, seldom or never. how does that come to pass? does a volcano make earthquakes? no; we may rather say that earthquakes are trying to make volcanos. for volcanos are the holes which the steam underground has burst open that it may escape into the air above. they are the chimneys of the great blast-furnaces underground, in which madam how pounds and melts up the old rocks, to make them into new ones, and spread them out over the land above. and are there many volcanos in the world? you have heard of vesuvius, of course, in italy; and etna, in sicily; and hecla, in iceland. and you have heard, too, of kilauea, in the sandwich islands, and of pele's hair--the yellow threads of lava, like fine spun glass, which are blown from off its pools of fire, and which the sandwich islanders believed to be the hair of a goddess who lived in the crater;--and you have read, too, i hope, in miss yonge's _book of golden deeds_, the noble story of the christian chieftainess who, in order to persuade her subjects to become christians also, went down into the crater and defied the goddess of the volcano, and came back unhurt and triumphant. but if you look at the map, you will see that there are many, many more. get keith johnston's physical atlas from the schoolroom--of course it is there (for a schoolroom without a physical atlas is like a needle without an eye)--and look at the map which is called "phenomena of volcanic action." you will see in it many red dots, which mark the volcanos which are still burning: and black dots, which mark those which have been burning at some time or other, not very long ago, scattered about the world. sometimes they are single, like the red dot at otaheite, or at easter island in the pacific. sometimes the are in groups, or clusters, like the cluster at the sandwich islands, or in the friendly islands, or in new zealand. and if we look in the atlantic, we shall see four clusters: one in poor half- destroyed iceland, in the far north, one in the azores, one in the canaries, and one in the cape de verds. and there is one dot in those canaries which we must not overlook, for it is no other than the famous peak of teneriffe, a volcano which is hardly burnt out yet, and may burn up again any day, standing up out of the sea more than , feet high still, and once it must have been double that height. some think that it is perhaps the true mount atlas, which the old greeks named when first they ventured out of the straits of gibraltar down the coast of africa, and saw the great peak far to the westward, with the clouds cutting off its top; and said that it was a mighty giant, the brother of the evening star, who held up the sky upon his shoulders, in the midst of the fortunate islands, the gardens of the daughter of the evening star, full of strange golden fruits; and that perseus had turned him into stone, when he passed him with the gorgon's head. but you will see, too, that most of these red and black dots run in crooked lines; and that many of the clusters run in lines likewise. look at one line: by far the largest on the earth. you will learn a good deal of geography from it. the red dots begin at a place called the terribles, on the east side of the bay of bengal. they run on, here and there, along the islands of sumatra and java, and through the spice islands; and at new guinea the line of red dots forks. one branch runs south-east, through islands whose names you never heard, to the friendly islands, and to new zealand. the other runs north, through the philippines, through japan, through kamschatka; and then there is a little break of sea, between asia and america: but beyond it, the red dots begin again in the aleutian islands, and then turn down the whole west coast of america, down from mount elias (in what was, till lately, russian america) towards british columbia. then, after a long gap, there are one or two in lower california (and we must not forget the terrible earthquake which has just shaken san francisco, between those two last places); and when we come down to mexico we find the red dots again plentiful, and only too plentiful; for they mark the great volcanic line of mexico, of which you will read, i hope, some day, in humboldt's works. but the line does not stop there. after the little gap of the isthmus of panama, it begins again in quito, the very country which has just been shaken, and in which stand the huge volcanos chimborazo, pasto, antisana, cotopaxi, pichincha, tunguragua,--smooth cones from , to , feet high, shining white with snow, till the heat inside melts it off, and leaves the cinders of which the peaks are made all black and ugly among the clouds, ready to burst in smoke and fire. south of them again, there is a long gap, and then another line of red dots--arequiba, chipicani, gualatieri, atacama,--as high as, or higher than those in quito; and this, remember, is the other country which has just been shaken. on the sea-shore below those volcanos stood the hapless city of arica, whose ruins we saw in the picture. then comes another gap; and then a line of more volcanos in chili, at the foot of which happened that fearful earthquake of (besides many more) of which you will read some day in that noble book _the voyage of the beagle_; and so the line of dots runs down to the southernmost point of america. what a line we have traced! long enough to go round the world if it were straight. a line of holes out of which steam, and heat, and cinders, and melted stones are rushing up, perpetually, in one place and another. now the holes in this line which are near each other have certainly something to do with each other. for instance, when the earth shook the other day round the volcanos of quito, it shook also round the volcanos of peru, though they were miles away. and there are many stories of earthquakes being felt, or awful underground thunder heard, while volcanos were breaking out hundreds of miles away. i will give you a very curious instance of that. if you look at the west indies on the map, you will see a line of red dots runs through the windward islands: there are two volcanos in them, one in guadaloupe, and one in st. vincent (i will tell you a curious story, presently, about that last), and little volcanos (if they have ever been real volcanos at all), which now only send out mud, in trinidad. there the red dots stop: but then begins along the north coast of south america a line of mountain country called cumana, and caraccas, which has often been horribly shaken by earthquakes. now once, when the volcano in st. vincent began to pour out a vast stream of melted lava, a noise like thunder was heard underground, over thousands of square miles beyond those mountains, in the plains of calabozo, and on the banks of the apure, more than miles away from the volcano,--a plain sign that there was something underground which joined them together, perhaps a long crack in the earth. look for yourselves at the places, and you will see that (as humboldt says) it is as strange as if an eruption of mount vesuvius was heard in the north of france. so it seems as if these lines of volcanos stood along cracks in the rind of the earth, through which the melted stuff inside was for ever trying to force its way; and that, as the crack got stopped up in one place by the melted stuff cooling and hardening again into stone, it was burst in another place, and a fresh volcano made, or an old one re-opened. now we can understand why earthquakes should be most common round volcanos; and we can understand, too, why they would be worst before a volcano breaks out, because then the steam is trying to escape; and we can understand, too, why people who live near volcanos are glad to see them blazing and spouting, because then they have hope that the steam has found its way out, and will not make earthquakes any more for a while. but still that is merely foolish speculation on chance. volcanos can never be trusted. no one knows when one will break out, or what it will do; and those who live close to them--as the city of naples is close to mount vesuvius--must not be astonished if they are blown up or swallowed up, as that great and beautiful city of naples may be without a warning, any day. for what happened to that same mount vesuvius nearly years ago, in the old roman times? for ages and ages it had been lying quiet, like any other hill. beautiful cities were built at its foot, filled with people who were as handsome, and as comfortable, and (i am afraid) as wicked, as people ever were on earth. fair gardens, vineyards, olive-yards, covered the mountain slopes. it was held to be one of the paradises of the world. as for the mountain's being a burning mountain, who ever thought of that? to be sure, on the top of it was a great round crater, or cup, a mile or more across, and a few hundred yards deep. but that was all overgrown with bushes and wild vines, full of boars and deer. what sign of fire was there in that? to be sure, also, there was an ugly place below by the sea-shore, called the phlegraen fields, where smoke and brimstone came out of the ground, and a lake called avernus over which poisonous gases hung, and which (old stories told) was one of the mouths of the nether pit. but what of that? it had never harmed any one, and how could it harm them? so they all lived on, merrily and happily enough, till, in the year a.d. (that was eight years, you know, after the emperor titus destroyed jerusalem), there was stationed in the bay of naples a roman admiral, called pliny, who was also a very studious and learned man, and author of a famous old book on natural history. he was staying on shore with his sister; and as he sat in his study she called him out to see a strange cloud which had been hanging for some time over the top of mount vesuvius. it was in shape just like a pine-tree; not, of course, like one of our branching scotch firs here, but like an italian stone pine, with a long straight stem and a flat parasol-shaped top. sometimes it was blackish, sometimes spotted; and the good admiral pliny, who was always curious about natural science, ordered his cutter and went away across the bay to see what it could be. earthquake shocks had been very common for the last few days; but i do not suppose that pliny had any notion that the earthquakes and the cloud had aught to do with each other. however, he soon found out that they had, and to his cost. when he got near the opposite shore some of the sailors met him and entreated him to turn back. cinders and pumice-stones were falling down from the sky, and flames breaking out of the mountain above. but pliny would go on: he said that if people were in danger, it was his duty to help them; and that he must see this strange cloud, and note down the different shapes into which it changed. but the hot ashes fell faster and faster; the sea ebbed out suddenly, and left them nearly dry, and pliny turned away to a place called stabiae, to the house of his friend pomponianus, who was just going to escape in a boat. brave pliny told him not to be afraid, ordered his bath like a true roman gentleman, and then went into dinner with a cheerful face. flames came down from the mountain, nearer and nearer as the night drew on; but pliny persuaded his friend that they were only fires in some villages from which the peasants had fled, and then went to bed and slept soundly. however, in the middle of the night they found the courtyard being fast filled with cinders, and, if they had not woke up the admiral in time, he would never have been able to get out of the house. the earthquake shocks grew stronger and fiercer, till the house was ready to fall; and pliny and his friend, and the sailors and the slaves, all fled into the open fields, amid a shower of stones and cinders, tying pillows over their heads to prevent their being beaten down. the day had come by this time, but not the dawn--for it was still pitch dark as night. they went down to their boats upon the shore; but the sea raged so horribly that there was no getting on board of them. then pliny grew tired, and made his men spread a sail for him, and lay down on it; but there came down upon them a rush of flames, and a horrible smell of sulphur, and all ran for their lives. some of the slaves tried to help the admiral upon his legs; but he sank down again overpowered with the brimstone fumes, and so was left behind. when they came back again, there he lay dead, but with his clothes in order and his face as quiet as if he had been only sleeping. and that was the end of a brave and learned man--a martyr to duty and to the love of science. but what was going on in the meantime? under clouds of ashes, cinders, mud, lava, three of those happy cities were buried at once--herculaneum, pompeii, stabiae. they were buried just as the people had fled from them, leaving the furniture and the earthenware, often even jewels and gold, behind, and here and there among them a human being who had not had time to escape from the dreadful deluge of dust. the ruins of herculaneum and pompeii have been dug into since; and the paintings, especially in pompeii, are found upon the walls still fresh, preserved from the air by the ashes which have covered them in. when you are older you perhaps will go to naples, and see in its famous museum the curiosities which have been dug out of the ruined cities; and you will walk, i suppose, along the streets of pompeii and see the wheel-tracks in the pavement, along which carts and chariots rumbled years ago. meanwhile, if you go nearer home, to the crystal palace and to the pompeian court, as it is called, you will see an exact model of one of these old buried houses, copied even to the very paintings on the wells, and judge for yourself, as far as a little boy can judge, what sort of life these thoughtless, luckless people lived years ago. and what had become of vesuvius, the treacherous mountain? half or more than half of the side of the old crater had been blown away, and what was left, which is now called the monte somma, stands in a half circle round the new cone and new crater which is burning at this very day. true, after that eruption which killed pliny, vesuvius fell asleep again, and did not awake for years, and then again for years but it has been growing more and more restless as the ages have passed on, and now hardly a year passes without its sending out smoke and stones from its crater, and streams of lava from its sides. and now, i suppose, you will want to know what a volcano is like, and what a cone, and a crater, and lava are? what a volcano is like, it is easy enough to show you; for they are the most simply and beautifully shaped of all mountains, and they are alike all over the world, whether they be large or small. almost every volcano in the world, i believe, is, or has been once, of the shape which you see in the drawing opposite; even those volcanos in the sandwich islands, of which you have often heard, which are now great lakes of boiling fire upon flat downs, without any cone to them at all. they, i believe, are volcanos which have fallen in ages ago: just as in java a whole burning mountain fell in on the night of the th of august, in the year . then, after a short and terrible earthquake, a bright cloud suddenly covered the whole mountain. the people who dwelt around it tried to escape; but before the poor souls could get away the earth sunk beneath their feet, and the whole mountain fell in and was swallowed up with a noise as if great cannon were being fired. forty villages and nearly people were destroyed, and where the mountain had been was only a plain of red-hot stones. in the same way, in the year , the top of a mountain in quito fell in in a single night, leaving only two immense peaks of rock behind, and pouring out great floods of mud mixed with dead fish; for there are underground lakes among those volcanos which swarm with little fish which never see the light. but most volcanos as i say, are, or have been, the shape of the one which you see here. this is cotopaxi, in quito, more than , feet in height. all those sloping sides are made of cinders and ashes, braced together, i suppose, by bars of solid lava-stone inside, which prevent the whole from crumbling down. the upper part, you see, is white with snow, as far down as a line which is , feet above the sea; for the mountain is in the tropics, close to the equator, and the snow will not lie in that hot climate any lower down. but now and then the snow melts off and rushes down the mountain side in floods of water and of mud, and the cindery cone of cotopaxi stands out black and dreadful against the clear blue sky, and then the people of that country know what is coming. the mountain is growing so hot inside that it melts off its snowy covering; and soon it will burst forth with smoke and steam, and red-hot stones and earthquakes, which will shake the ground, and roars that will be heard, it may be, hundreds of miles away. and now for the words cone, crater, lava. if i can make you understand those words, you will see why volcanos must be in general of the shape of cotopaxi. cone, crater, lava: those words make up the alphabet of volcano learning. the cone is the outside of a huge chimney; the crater is the mouth of it. the lava is the ore which is being melted in the furnace below, that it may flow out over the surface of the old land, and make new land instead. and where is the furnace itself? who can tell that? under the roots of the mountains, under the depths of the sea; down "the path which no fowl knoweth, and which the vulture's eye hath not seen: the lion's whelp hath not trodden it, nor the fierce lion passed by it. there he putteth forth his hand upon the rock; he overturneth the mountain by the roots; he cutteth out rivers among the rocks; and his eye seeth every precious thing"--while we, like little ants, run up and down outside the earth, scratching, like ants, a few feet down, and calling that a deep ravine; or peeping a few feet down into the crater of a volcano, unable to guess what precious things may lie below--below even the fire which blazes and roars up through the thin crust of the earth. for of the inside of this earth we know nothing whatsoever: we only know that it is, on an average, several times as heavy as solid rock; but how that can be, we know not. so let us look at the chimney, and what comes out of it; for we can see very little more. why is a volcano like a cone? for the same cause for which a molehill is like a cone, though a very rough one; and that the little heaps which the burrowing beetles make on the moor, or which the ant-lions in france make in the sand, are all something in the shape of a cone, with a hole like a crater in the middle. what the beetle and the ant-lion do on a very little scale, the steam inside the earth does on a great scale. when once it has forced a vent into the outside air, it tears out the rocks underground, grinds them small against each other, often into the finest dust, and blasts them out of the hole which it has made. some of them fall back into the hole, and are shot out again: but most of them fall round the hole, most of them close to it, and fewer of them farther off, till they are piled up in a ring round it, just as the sand is piled up round a beetle's burrow. for days, and weeks, and months this goes on; even it may be for hundreds of years: till a great cone is formed round the steam vent, hundreds or thousands of feet in height, of dust and stones, and of cinders likewise. for recollect, that when the steam has blown away the cold earth and rock near the surface of the ground, it begins blowing out the hot rocks down below, red-hot, white-hot, and at last actually melted. but these, as they are hurled into the cool air above, become ashes, cinders, and blocks of stone again, making the hill on which they fall bigger and bigger continually. and thus does wise madam how stand in no need of bricklayers, but makes her chimneys build themselves. and why is the mouth of the chimney called a crater? crater, as you know, is greek for a cup. and the mouth of these chimneys, when they have become choked and stopped working, are often just the shape of a cup, or (as the germans call them) kessels, which means kettles, or caldrons. i have seen some of them as beautifully and exactly rounded as if a cunning engineer had planned them, and had them dug out with the spade. at first, of course, their sides and bottom are nothing but loose stones, cinders, slag, ashes, such as would be thrown out of a furnace. but madam how, who, whenever she makes an ugly desolate place, always tries to cover over its ugliness, and set something green to grow over it, and make it pretty once more, does so often and often by her worn-out craters. i have seen them covered with short sweet turf, like so many chalk downs. i have seen them, too, filled with bushes, which held woodcocks and wild boars. once i came on a beautiful round crater on the top of a mountain, which was filled at the bottom with a splendid crop of potatoes. though madam how had not put them there herself, she had at least taught the honest germans to put them there. and often madam how turns her worn-out craters into beautiful lakes. there are many such crater-lakes in italy, as you will see if ever you go there; as you may see in english galleries painted by wilson, a famous artist who died before you were born. you recollect lord macaulay's ballad, "the battle of the lake regillus"? then that lake regillus (if i recollect right) is one of these round crater lakes. many such deep clear blue lakes have i seen in the eifel, in germany; and many a curious plant have i picked on their shores, where once the steam blasted, and the earthquake roared, and the ash-clouds rushed up high into the heaven, and buried all the land around in dust, which is now fertile soil. and long did i puzzle to find out why the water stood in some craters, while others, within a mile of them perhaps, were perfectly dry. that i never found out for myself. but learned men tell me that the ashes which fall back into the crater, if the bottom of it be wet from rain, will sometimes "set" (as it is called) into a hard cement; and so make the bottom of the great bowl waterproof, as if it were made of earthenware. but what gives the craters this cup-shape at first? think--while the steam and stones are being blown out, the crater is an open funnel, with more or less upright walls inside. as the steam grows weaker, fewer and fewer stones fall outside, and more and more fall back again inside. at last they quite choke up the bottom of the great round hole. perhaps, too, the lava or melted rock underneath cools and grows hard, and that chokes up the hole lower down. then, down from the round edge of the crater the stones and cinders roll inward more and more. the rains wash them down, the wind blows them down. they roll to the middle, and meet each other, and stop. and so gradually the steep funnel becomes a round cup. you may prove for yourself that it must be so, if you will try. do you not know that if you dig a round hole in the ground, and leave it to crumble in, it is sure to become cup-shaped at last, though at first its sides may have been quite upright, like those of a bucket? if you do not know, get a trowel and make your little experiment. and now you ought to understand what "cone" and "crater" mean. and more, if you will think for yourself, you may guess what would come out of a volcano when it broke out "in an eruption," as it is usually called. first, clouds of steam and dust (what you would call smoke); then volleys of stones, some cool, some burning hot; and at the last, because it lies lowest of all, the melted rock itself, which is called lava. and where would that come out? at the top of the chimney? at the top of the cone? no. madam how, as i told you, usually makes things make themselves. she has made the chimney of the furnace make itself; and next she will make the furnace-door make itself. the melted lava rises in the crater--the funnel inside the cone--but it never gets to the top. it is so enormously heavy that the sides of the cone cannot bear its weight, and give way low down. and then, through ashes and cinders, the melted lava burrows out, twisting and twirling like an enormous fiery earth-worm, till it gets to the air outside, and runs off down the mountain in a stream of fire. and so you may see (as are to be seen on vesuvius now) two eruptions at once--one of burning stones above, and one of melted lava below. and what is lava? that, i think, i must tell you another time. for when i speak of it i shall have to tell you more about madam how, and her ways of making the ground on which you stand, than i can say just now. but if you want to know (as i dare say you do) what the eruption of a volcano is like, you may read what follows. i did not see it happen; for i never had the good fortune of seeing a mountain burning, though i have seen many and many a one which has been burnt--extinct volcanos, as they are called. the man who saw it--a very good friend of mine, and a very good man of science also--went last year to see an eruption on vesuvius, not from the main crater, but from a small one which had risen up suddenly on the outside of it; and he gave me leave (when i told him that i was writing for children) to tell them what he saw. this new cone, he said, was about feet high, and perhaps or feet across at the top. and as he stood below it (it was not safe to go up it) smoke rolled up from its top, "rosy pink below," from the glare of the caldron, and above "faint greenish or blueish silver of indescribable beauty, from the light of the moon." but more--by good chance, the cone began to send out, not smoke only, but brilliant burning stones. "each explosion," he says, "was like a vast girandole of rockets, with a noise (such as rockets would make) like the waves on a beach, or the wind blowing through shrouds. the mountain was trembling the whole time. so it went on for two hours and more; sometimes eight or ten explosions in a minute, and more than stones in each, some as large as two bricks end to end. the largest ones mostly fell back into the crater; but the smaller ones being thrown higher, and more acted on by the wind, fell in immense numbers on the leeward slope of the cone" (of course, making it bigger and bigger, as i have explained already to you), and of course, as they were intensely hot and bright, making the cone look as if it too was red-hot. but it was not so, he says, really. the colour of the stones was rather "golden, and they spotted the black cone over with their golden showers, the smaller ones stopping still, the bigger ones rolling down, and jumping along just like hares." "a wonderful pedestal," he says, "for the explosion which surmounted it." how high the stones flew up he could not tell. "there was generally one which went much higher than the rest, and pierced upwards towards the moon, who looked calmly down, mocking such vain attempts to reach her." the large stones, of course, did not rise so high; and some, he says, "only just appeared over the rim of the cone, above which they came floating leisurely up, to show their brilliant forms and intense white light for an instant, and then subside again." try and picture that to yourselves, remembering that this was only a little side eruption, of no more importance to the whole mountain than the fall of a slate off the roof is of importance to the whole house. and then think how mean and weak man's fireworks, and even man's heaviest artillery, are compared with the terrible beauty and terrible strength of madam how's artillery underneath our feet. c / | \ / | \ a /---+---\ e / | \ /-----+-----\ e ground / | b \ ground ---------/ | \------------ | d | | d | d | --+-----+--+---+-----+------ | | | | | | now look at this figure. it represents a section of a volcano; that is, one cut in half to show you the inside. a is the cone of cinders. b, the black line up through the middle, is the funnel, or crack, through which steam, ashes, lava, and everything else rises. c is the crater mouth. d d d, which looks broken, are the old rocks which the steam heaved up and burst before it could get out. and what are the black lines across, marked e e e? they are the streams of lava which have burrowed out, some covered up again in cinders, some lying bare in the open air, some still inside the cone, bracing it together, holding it up. something like this is the inside of a volcano. chapter iv--the transformations of a grain of soil why, you ask, are there such terrible things as volcanos? of what use can they be? they are of use enough, my child; and of many more uses, doubt not, than we know as yet, or ever shall know. but of one of their uses i can tell you. they make, or help to make, divers and sundry curious things, from gunpowder to your body and mine. what? i can understand their helping to make gunpowder, because the sulphur in it is often found round volcanos; and i know the story of the brave spaniard who, when his fellows wanted materials for gunpowder, had himself lowered in a basket down the crater of a south american volcano, and gathered sulphur for them off the burning cliffs: but how can volcanos help to make me? am i made of lava? or is there lava in me? my child, i did not say that volcanos helped to make you. i said that they helped to make your body; which is a very different matter, as i beg you to remember, now and always. your body is no more you yourself than the hoop which you trundle, or the pony which you ride. it is, like them, your servant, your tool, your instrument, your organ, with which you work: and a very useful, trusty, cunningly-contrived organ it is; and therefore i advise you to make good use of it, for you are responsible for it. but you yourself are not your body, or your brain, but something else, which we call your soul, your spirit, your life. and that "you yourself" would remain just the same if it were taken out of your body, and put into the body of a bee, or of a lion, or any other body; or into no body at all. at least so i believe; and so, i am happy to say, nine hundred and ninety-nine thousand nine hundred and ninety-nine people out of every million have always believed, because they have used their human instincts and their common sense, and have obeyed (without knowing it) the warning of a great and good philosopher called herder, that "the organ is in no case the power which works by it;" which is as much as to say, that the engine is not the engine-driver, nor the spade the gardener. there have always been, and always will be, a few people who cannot see that. they think that a man's soul is part of his body, and that he himself is not one thing, but a great number of things. they think that his mind and character are only made up of all the thoughts, and feelings, and recollections which have passed through his brain; and that as his brain changes, he himself must change, and become another person, and then another person again, continually. but do you not agree with them: but keep in mind wise herder's warning that you are not to "confound the organ with the power," or the engine with the driver, or your body with yourself: and then we will go on and consider how a volcano, and the lava which flows from it, helps to make your body. now i know that the scotch have a saying, "that you cannot make broth out of whinstones" (which is their name for lava). but, though they are very clever people, they are wrong there. i never saw any broth in scotland, as far as i know, but what whinstones had gone to the making of it; nor a scotch boy who had not eaten many a bit of whinstone, and been all the better for it. of course, if you simply put the whinstones into a kettle and boiled them, you would not get much out of them by such rough cookery as that. but madam how is the best and most delicate of all cooks; and she knows how to pound, and soak, and stew whinstones so delicately, that she can make them sauce and seasoning for meat, vegetables, puddings, and almost everything that you eat; and can put into your veins things which were spouted up red-hot by volcanos, ages and ages since, perhaps at the bottom of ancient seas which are now firm dry land. this is very strange--as all madam how's doings are. and you would think it stranger still if you had ever seen the flowing of a lava stream. out of a cave of slag and cinders in the black hillside rushes a golden river, flowing like honey, and yet so tough that you cannot thrust a stick into it, and so heavy that great stones (if you throw them on it) float on the top, and are carried down like corks on water. it is so hot that you cannot stand near it more than a few seconds; hotter, perhaps, than any fire you ever saw: but as it flows, the outside of it cools in the cool air, and gets covered with slag and cinders, something like those which you may see thrown out of the furnaces in the black country of staffordshire. sometimes these cling together above the lava stream, and make a tunnel, through the cracks in which you may see the fiery river rushing and roaring down below. but mostly they are kept broken and apart, and roll and slide over each other on the top of the lava, crashing and clanging as they grind together with a horrid noise. of course that stream, like all streams, runs towards the lower grounds. it slides down glens, and fills them up; down the beds of streams, driving off the water in hissing steam; and sometimes (as it did in iceland a few years ago) falls over some cliff, turning what had been a water-fall into a fire-fall, and filling up the pool below with blocks of lava suddenly cooled, with a clang and roar like that of chains shaken or brazen vessels beaten, which is heard miles and miles away. of course, woe to the crops and gardens which stand in its way. it crawls over them all and eats them up. it shoves down houses; it sets woods on fire, and sends the steam and gas out of the tree-trunks hissing into the air. and (curiously enough) it does this often without touching the trees themselves. it flows round the trunks (it did so in a wood in the sandwich islands a few years ago), and of course sets them on fire by its heat, till nothing is left of them but blackened posts. but the moisture which comes out of the poor tree in steam blows so hard against the lava round that it can never touch the tree, and a round hole is left in the middle of the lava where the tree was. sometimes, too, the lava will spit out liquid fire among the branches of the trees, which hangs down afterwards from them in tassels of slag, and yet, by the very same means, the steam in the branches will prevent the liquid fire burning them off, or doing anything but just scorch the bark. but i can tell you a more curious story still. the lava stream, you must know, is continually sending out little jets of gas and steam: some of it it may have brought up from the very inside of the earth; most of it, i suspect, comes from the damp herbage and damp soil over which it runs. be that as it may, a lava stream out of mount etna, in sicily, came once down straight upon the town of catania. everybody thought that the town would be swallowed up; and the poor people there (who knew no better) began to pray to st. agatha--a famous saint, who, they say, was martyred there ages ago--and who, they fancy, has power in heaven to save them from the lava stream. and really what happened was enough to make ignorant people, such as they were, think that st. agatha had saved them. the lava stream came straight down upon the town wall. another foot, and it would have touched it, and have begun shoving it down with a force compared with which all the battering-rams that you ever read of in ancient histories would be child's toys. but lo and behold! when the lava stream got within a few inches of the wall it stopped, and began to rear itself upright and build itself into a wall beside the wall. it rose and rose, till i believe in one place it overtopped the wall and began to curl over in a crest. all expected that it would fall over into the town at last: but no, there it stopped, and cooled, and hardened, and left the town unhurt. all the inhabitants said, of course, that st. agatha had done it: but learned men found out that, as usual madam how had done it, by making it do itself. the lava was so full of gas, which was continually blowing out in little jets, that when it reached the wall, it actually blew itself back from the wall; and, as the wall was luckily strong enough not to be blown down, the lava kept blowing itself back till it had time to cool. and so, my dear child, there was no miracle at all in the matter; and the poor people of catania had to thank not st. agatha, and any interference of hers, but simply him who can preserve, just as he can destroy, by those laws of nature which are the breath of his mouth and the servants of his will. but in many a case the lava does not stop. it rolls on and on over the downs and through the valleys, till it reaches the sea-shore, as it did in hawaii in the sandwich islands this very year. and then it cools, of course; but often not before it has killed the fish by its sulphurous gases and heat, perhaps for miles around. and there is good reason to believe that the fossil fish which we so often find in rocks, perfect in every bone, lying sometimes in heaps, and twisted (as i have seen them) as if they had died suddenly and violently, were killed in this very way, either by heat from lava streams, or else by the bursting up of gases poisoning the water, in earthquakes and eruptions in the bottom of the sea. i could tell you many stories of fish being killed in thousands by earthquakes and volcanos during the last few years. but we have not time to tell about everything. and now you will ask me, with more astonishment than ever, what possible use can there be in these destroying streams of fire? and certainly, if you had ever seen a lava stream even when cool, and looked down, as i have done, at the great river of rough black blocks streaming away far and wide over the land, you would think it the most hideous and the most useless thing you ever saw. and yet, my dear child, there is one who told men to judge not according to the appearance, but to judge righteous judgment. he said that about matters spiritual and human: but it is quite as true about matters natural, which also are his work, and all obey his will. now if you had seen, as i have seen, close round the edges of these lava streams, and sometimes actually upon them, or upon the great bed of dust and ashes which have been hurled far and wide out of ancient volcanos, happy homesteads, rich crops, hemp and flax, and wheat, tobacco, lucerne, roots, and vineyards laden with white and purple grapes, you would have begun to suspect that the lava streams were not, after all, such very bad neighbours. and when i tell you that volcanic soils (as they are called), that is, soil which has at first been lava or ashes, are generally the richest soils in the world--that, for instance (as some one told me the other day), there is soil in the beautiful island of madeira so thin that you cannot dig more than two or three inches down without coming to the solid rock of lava, or what is harder even, obsidian (which is the black glass which volcanos sometimes make, and which the old mexicans used to chip into swords and arrows, because they had no steel)--and that this soil, thin as it is, is yet so fertile, that in it used to be grown the grapes of which the famous madeira wine was made--when you remember this, and when you remember, too, the lothians of scotland (about which i shall have to say a little to you just now), then you will perhaps agree with me, that lady why has not been so very wrong in setting madam how to pour out lava and ashes upon the surface of the earth. for see--down below, under the roots of the mountains, madam how works continually like a chemist in his laboratory, melting together all the rocks, which are the bones and leavings of the old worlds. if they stayed down below there, they would be of no use; while they will be of use up here in the open air. for, year by year--by the washing of rain and rivers, and also, i am sorry to say, by the ignorant and foolish waste of mankind--thousands and millions of tons of good stuff are running into the sea every year, which would, if it could be kept on land, make food for men and animals, plants and trees. so, in order to supply the continual waste of this upper world, madam how is continually melting up the under world, and pouring it out of the volcanos like manure, to renew the face of the earth. in these lava rocks and ashes which she sends up there are certain substances, without which men cannot live--without which a stalk of corn or grass cannot grow. without potash, without magnesia, both of which are in your veins and mine--without silicates (as they are called), which give flint to the stems of corn and of grass, and so make them stiff and hard, and able to stand upright--and very probably without the carbonic acid gas, which comes out of the volcanos, and is taken up by the leaves of plants, and turned by madam how's cookery into solid wood--without all these things, and i suspect without a great many more things which come out of volcanos--i do not see how this beautiful green world could get on at all. of course, when the lava first cools on the surface of the ground it is hard enough, and therefore barren enough. but madam how sets to work upon it at once, with that delicate little water-spade of hers, which we call rain, and with that alone, century after century, and age after age, she digs the lava stream down, atom by atom, and silts it over the country round in rich manure. so that if madam how has been a rough and hasty workwoman in pumping her treasures up out of her mine with her great steam-pumps, she shows herself delicate and tender and kindly enough in giving them away afterwards. nay, even the fine dust which is sometimes blown out of volcanos is useful to countries far away. so light it is, that it rises into the sky and is wafted by the wind across the seas. so, in the year , ashes from the skaptar jokull, in iceland, were carried over the north of scotland, and even into holland, hundreds of miles to the south. so, again, when in the year the volcano of st. vincent, in the west india islands, poured out torrents of lava, after mighty earthquakes which shook all that part of the world, a strange thing happened (about which i have often heard from those who saw it) in the island of barbados, several hundred miles away. for when the sun rose in the morning (it was a sunday morning), the sky remained more dark than any night, and all the poor negroes crowded terrified out of their houses into the streets, fancying the end of the world was come. but a learned man who was there, finding that, though the sun was risen, it was still pitchy dark, opened his window, and found that it was stuck fast by something on the ledge outside, and, when he thrust it open, found the ledge covered deep in soft red dust; and he instantly said, like a wise man as he was, "the volcano of st. vincent must have broken out, and these are the ashes from it." then he ran down stairs and quieted the poor negroes, telling them not to be afraid, for the end of the world was not coming just yet. but still the dust went on falling till the whole island, i am told, was covered an inch thick; and the same thing happened in the other islands round. people thought--and they had reason to think from what had often happened elsewhere--that though the dust might hurt the crops for that year, it would make them richer in years to come, because it would act as manure upon the soil; and so it did after a few years; but it did terrible damage at the time, breaking off the boughs of trees and covering up the crops; and in st. vincent itself whole estates were ruined. it was a frightful day, but i know well that behind that how there was a why for its happening, and happening too, about that very time, which all who know the history of negro slavery in the west indies can guess for themselves, and confess, i hope, that in this case, as in all others, when lady why seems most severe she is often most just and kind. ah! my dear child, that i could go on talking to you of this for hours and days! but i have time now only to teach you the alphabet of these matters--and, indeed, i know little more than the alphabet myself; but if the very letters of madam how's book, and the mere a, b, ab, of it, which i am trying to teach you, are so wonderful and so beautiful, what must its sentences be and its chapters? and what must the whole book be like? but that last none can read save he who wrote it before the worlds were made. but now i see you want to ask a question. let us have it out. i would sooner answer one question of yours than tell you ten things without your asking. is there potash and magnesia and silicates in the soil here? and if there is, where did they come from? for there are no volcanos in england. yes. there are such things in the soil; and little enough of them, as the farmers here know too well. for we here, in windsor forest, are on the very poorest and almost the newest soil in england; and when madam how had used up all her good materials in making the rest of the island, she carted away her dry rubbish and shot it down here for us to make the best of; and i do not think that we and our forefathers have done so very ill with it. but where the rich part, or staple, of our soils came from first it would be very difficult to say, so often has madam how made, and unmade, and re-made england, and sifted her materials afresh every time. but if you go to the lowlands of scotland, you may soon see where the staple of the soil came from there, and that i was right in saying that there were atoms of lava in every scotch boy's broth. not that there were ever (as far as i know) volcanos in scotland or in england. madam how has more than one string to her bow, or two strings either; so when she pours out her lavas, she does not always pour them out in the open air. sometimes she pours them out at the bottom of the sea, as she did in the north of ireland and the south-west of scotland, when she made the giant's causeway, and fingal's cave in staffa too, at the bottom of the old chalk ocean, ages and ages since. sometimes she squirts them out between the layers of rock, or into cracks which the earthquakes have made, in what are called trap dykes, of which there are plenty to be seen in scotland, and in wales likewise. and then she lifts the earth up from the bottom of the sea, and sets the rain to wash away all the soft rocks, till the hard lava stands out in great hills upon the surface of the ground. then the rain begins eating away those lava-hills likewise, and manuring the earth with them; and wherever those lava-hills stand up, whether great or small, there is pretty sure to be rich land around them. if you look at the geological map of england and ireland, and the red spots upon it, which will show you where those old lavas are, you will see how much of them there is in england, at the lizard point in cornwall, and how much more in scotland and the north of ireland. in south devon, in shropshire--with its beautiful wrekin, and caradoc, and lawley--in wales, round snowdon (where some of the soil is very rich), and, above all, in the lowlands of scotland, you see these red marks, showing the old lavas, which are always fertile, except the poor old granite, which is of little use save to cut into building stone, because it is too full of quartz--that is, flint. think of this the next time you go through scotland in the railway, especially when you get near edinburgh. as you run through the lothians, with their noble crops of corn, and roots, and grasses--and their great homesteads, each with its engine chimney, which makes steam do the work of men--you will see rising out of the plain, hills of dark rock, sometimes in single knobs, like berwick law or stirling crag--sometimes in noble ranges, like arthur's seat, or the sidlaws, or the ochils. think what these black bare lumps of whinstone are, and what they do. remember they are mines--not gold mines, but something richer still--food mines, which madam how thrust into the inside of the earth, ages and ages since, as molten lava rock, and then cooled them and lifted them up, and pared them away with her ice-plough and her rain-spade, and spread the stuff of them over the wide carses round, to make in that bleak northern climate, which once carried nothing but fir-trees and heather, a soil fit to feed a great people; to cultivate in them industry, and science, and valiant self-dependence and self-help; and to gather round the heart of midlothian and the castle rock of edinburgh the stoutest and the ablest little nation which lady why has made since she made the greeks who fought at salamis. of those greeks you have read, or ought to read, in mr. cox's _tales of the persian war_. some day you will read of them in their own books, written in their grand old tongue. remember that lady why made them, as she has made the scotch, by first preparing a country for them, which would call out all their courage and their skill; and then by giving them the courage and the skill to make use of the land where she had put them. and now think what a wonderful fairy tale you might write for yourself--and every word of it true--of the adventures of one atom of potash or some other salt, no bigger than a needle's point, in such a lava stream as i have been telling of. how it has run round and round, and will run round age after age, in an endless chain of change. how it began by being molten fire underground, how then it became part of a hard cold rock, lifted up into a cliff, beaten upon by rain and storm, and washed down into the soil of the plain, till, perhaps, the little atom of mineral met with the rootlet of some great tree, and was taken up into its sap in spring, through tiny veins, and hardened the next year into a piece of solid wood. and then how that tree was cut down, and its logs, it may be, burnt upon the hearth, till the little atom of mineral lay among the wood-ashes, and was shovelled out and thrown upon the field and washed into the soil again, and taken up by the roots of a clover plant, and became an atom of vegetable matter once more. and then how, perhaps, a rabbit came by, and ate the clover, and the grain of mineral became part of the rabbit; and then how a hawk killed that rabbit, and ate it, and so the grain became part of the hawk; and how the farmer shot the hawk, and it fell perchance into a stream, and was carried down into the sea; and when its body decayed, the little grain sank through the water, and was mingled with the mud at the bottom of the sea. but do its wanderings stop there? not so, my child. nothing upon this earth, as i told you once before, continues in one stay. that grain of mineral might stay at the bottom of the sea a thousand or ten thousand years, and yet the time would come when madam how would set to work on it again. slowly, perhaps, she would sink that mud so deep, and cover it up with so many fresh beds of mud, or sand, or lime, that under the heavy weight, and perhaps, too, under the heat of the inside of the earth, that mud would slowly change to hard slate rock; and ages after, it may be, madam how might melt that slate rock once more, and blast it out; and then through the mouth of a volcano the little grain of mineral might rise into the open air again to make fresh soil, as it had done thousands of years before. for madam how can manufacture many different things out of the same materials. she may have so wrought with that grain of mineral, that she may have formed it into part of a precious stone, and men may dig it out of the rock, or pick it up in the river-bed, and polish it, and set it, and wear it. think of that--that in the jewels which your mother or your sisters wear, or in your father's signet ring, there may be atoms which were part of a live plant, or a live animal, millions of years ago, and may be parts of a live plant or a live animal millions of years hence. think over again, and learn by heart, the links of this endless chain of change: fire turned into stone--stone into soil--soil into plant--plant into animal--animal into soil--soil into stone--stone into fire again--and then fire into stone again, and the old thing run round once more. so it is, and so it must be. for all things which are born in time must change in time, and die in time, till that last day of this our little earth, in which, "like to the baseless fabric of a vision, the cloud-capped towers, the gorgeous palaces, the solemn temples, the great globe itself, yea, all things which inherit, shall dissolve, and, like an unsubstantial pageant faded, leave not a rack behind." so all things change and die, and so your body too must change and die--but not yourself. madam how made your body; and she must unmake it again, as she unmakes all her works in time and space; but you, child, your soul, and life, and self, she did not make; and over you she has no power. for you were not, like your body, created in time and space; and you will endure though time and space should be no more: because you are the child of the living god, who gives to each thing its own body, and can give you another body, even as seems good to him. chapter v--the ice-plough you want to know why i am so fond of that little bit of limestone, no bigger than my hand, which lies upon the shelf; why i ponder over it so often, and show it to all sensible people who come to see me? i do so, not only for the sake of the person who gave it to me, but because there is written on it a letter out of madam how's alphabet, which has taken wise men many a year to decipher. i could not decipher that letter when first i saw the stone. more shame for me, for i had seen it often before, and understood it well enough, in many another page of madam how's great book. take the stone, and see if you can find out anything strange about it. well, it is only a bit of marble as big as my hand, that looks as if it had been, and really has been, broken off by a hammer. but when you look again, you see there is a smooth scraped part on one edge, that seems to have been rubbed against a stone. now look at that rubbed part, and tell me how it was done. you have seen men often polish one stone on another, or scour floors with a bath brick, and you will guess at first that this was polished so: but if it had been, then the rubbed place would have been flat: but if you put your fingers over it, you will find that it is not flat. it is rolled, fluted, channelled, so that the thing or things which rubbed it must have been somewhat round. and it is covered, too, with very fine and smooth scratches or grooves, all running over the whole in the same line. now what could have done that? of course a man could have done it, if he had taken a large round stone in his hand, and worked the large channellings with that, and then had taken fine sand and gravel upon the points of his fingers, and worked the small scratches with that. but this stone came from a place where man had, perhaps, never stood before,--ay, which, perhaps, had never seen the light of day before since the world was made; and as i happen to know that no man made the marks upon that stone, we must set to work and think again for some tool of madam how's which may have made them. and now i think you must give up guessing, and i must tell you the answer to the riddle. those marks were made by a hand which is strong and yet gentle, tough and yet yielding, like the hand of a man; a hand which handles and uses in a grip stronger than a giant's its own carving tools, from the great boulder stone as large as this whole room to the finest grain of sand. and that is ice. that piece of stone came from the side of the rosenlaui glacier in switzerland, and it was polished by the glacier ice. the glacier melted and shrank this last hot summer farther back than it had done for many years, and left bare sheets of rock, which it had been scraping at for ages, with all the marks fresh upon them. and that bit was broken off and brought to me, who never saw a glacier myself, to show me how the marks which the ice makes in switzerland are exactly the same as those which the ice has made in snowdon and in the highlands, and many another place where i have traced them, and written a little, too, about them in years gone by. and so i treasure this, as a sign that madam how's ways do not change nor her laws become broken; that, as that great philosopher sir charles lyell will tell you, when you read his books, madam how is making and unmaking the surface of the earth now, by exactly the same means as she was making and unmaking ages and ages since; and that what is going on slowly and surely in the alps in switzerland was going on once here where we stand. it is very difficult, i know, for a little boy like you to understand how ice, and much more how soft snow, should have such strength that it can grind this little stone, much more such strength as to grind whole mountains into plains. you have never seen ice and snow do harm. you cannot even recollect the crimean winter, as it was called then; and well for you you cannot, considering all the misery it brought at home and abroad. you cannot, i say, recollect the crimean winter, when the thames was frozen over above the bridges, and the ice piled in little bergs ten to fifteen feet high, which lay, some of them, stranded on the shores, about london itself, and did not melt, if i recollect, until the end of may. you never stood, as i stood, in the great winter of - on battersea bridge, to see the ice break up with the tide, and saw the great slabs and blocks leaping and piling upon each other's backs, and felt the bridge tremble with their shocks, and listened to their horrible grind and roar, till one got some little picture in one's mind of what must be the breaking up of an ice-floe in the arctic regions, and what must be the danger of a ship nipped in the ice and lifted up on high, like those in the pictures of arctic voyages which you are so fond of looking through. you cannot recollect how that winter even in our little blackwater brook the alder stems were all peeled white, and scarred, as if they had been gnawed by hares and deer, simply by the rushing and scraping of the ice,--a sight which gave me again a little picture of the destruction which the ice makes of quays, and stages, and houses along the shore upon the coasts of north america, when suddenly setting in with wind and tide, it jams and piles up high inland, as you may read for yourself some day in a delightful book called _frost and fire_. you recollect none of these things. ice and snow are to you mere playthings; and you long for winter, that you may make snowballs and play hockey and skate upon the ponds, and eat ice like a foolish boy till you make your stomach ache. and i dare say you have said, like many another boy, on a bright cheery ringing frosty day, "oh, that it would be always winter!" you little knew for what you asked. you little thought what the earth would soon be like, if it were always winter,--if one sheet of ice on the pond glued itself on to the bottom of the last sheet, till the whole pond was a solid mass,--if one snow-fall lay upon the top of another snow-fall till the moor was covered many feet deep and the snow began sliding slowly down the glen from coombs's, burying the green fields, tearing the trees up by their roots, burying gradually house, church, and village, and making this place for a few thousand years what it was many thousand years ago. good-bye then, after a very few winters, to bees, and butterflies, and singing-birds, and flowers; and good-bye to all vegetables, and fruit, and bread; good-bye to cotton and woollen clothes. you would have, if you were left alive, to dress in skins, and eat fish and seals, if any came near enough to be caught. you would have to live in a word, if you could live at all, as esquimaux live now in arctic regions, and as people had to live in england ages since, in the times when it was always winter, and icebergs floated between here and finchampstead. oh no, my child: thank heaven that it is not always winter; and remember that winter ice and snow, though it is a very good tool with which to make the land, must leave the land year by year if that land is to be fit to live in. i said that if the snow piled high enough upon the moor, it would come down the glen in a few years through coombs's wood; and i said then you would have a small glacier here--such a glacier (to compare small things with great) as now comes down so many valleys in the alps, or has come down all the valleys of greenland and spitzbergen till they reach the sea, and there end as cliffs of ice, from which great icebergs snap off continually, and fall and float away, wandering southward into the atlantic for many a hundred miles. you have seen drawings of such glaciers in captain cook's voyages; and you may see photographs of swiss glaciers in any good london print-shop; and therefore you have seen almost as much about them as i have seen, and may judge for yourself how you would like to live where it is always winter. now you must not ask me to tell you what a glacier is like, for i have never seen one; at least, those which i have seen were more than fifty miles away, looking like white clouds hanging on the gray mountain sides. and it would be an impertinence--that means a meddling with things which i have no business--to picture to you glaciers which have been pictured so well and often by gentlemen who escape every year from their hard work in town to find among the glaciers of the alps health and refreshment, and sound knowledge, and that most wholesome and strengthening of all medicines, toil. so you must read of them in such books as _peaks, passes, and glaciers_, and mr. willes's _wanderings in the high alps_, and professor tyndall's different works; or you must look at them (as i just now said) in photographs or in pictures. but when you do that, or when you see a glacier for yourself, you must bear in mind what a glacier means--that it is a river of ice, fed by a lake of snow. the lake from which it springs is the eternal snow-field which stretches for miles and miles along the mountain tops, fed continually by fresh snow-storms falling from the sky. that snow slides off into the valleys hour by hour, and as it rushes down is ground and pounded, and thawed and frozen again into a sticky paste of ice, which flows slowly but surely till it reaches the warm valley at the mountain foot, and there melts bit by bit. the long black lines which you see winding along the white and green ice of the glacier are the stones which have fallen from the cliffs above. they will be dropped at the end of the glacier, and mixed with silt and sand and other stones which have come down inside the glacier itself, and piled up in the field in great mounds, which are called moraines, such as you may see and walk on in scotland many a time, though you might never guess what they are. the river which runs out at the glacier foot is, you must remember, all foul and milky with the finest mud; and that mud is the grinding of the rocks over which the glacier has been crawling down, and scraping them as it scraped my bit of stone with pebbles and with sand. and this is the alphabet, which, if you learn by heart, you will learn to understand how madam how uses her great ice-plough to plough down her old mountains, and spread the stuff of them about the valleys to make rich straths of fertile soil. nay, so immensely strong, because immensely heavy, is the share of this her great ice-plough, that some will tell you (and it is not for me to say that they are wrong) that with it she has ploughed out all the mountain lakes in europe and in north america; that such lakes, for instance, as ullswater or windermere have been scooped clean out of the solid rock by ice which came down these glaciers in old times. and be sure of this, that next to madam how's steam-pump and her rain-spade, her great ice-plough has had, and has still, the most to do with making the ground on which we live. do i mean that there were ever glaciers here? no, i do not. there have been glaciers in scotland in plenty. and if any scotch boy shall read this book, it will tell him presently how to find the marks of them far and wide over his native land. but as you, my child, care most about this country in which you live, i will show you in any gravel-pit, or hollow lane upon the moor, the marks, not of a glacier, which is an ice- river, but of a whole sea of ice. let us come up to the pit upon the top of the hill, and look carefully at what we see there. the lower part of the pit of course is a solid rock of sand. on the top of that is a cap of gravel, five, six, ten feet thick. now the sand was laid down there by water at the bottom of an old sea; and therefore the top of it would naturally be flat and smooth, as the sands at hunstanton or at bournemouth are; and the gravel, if it was laid down by water, would naturally lie flat on it again: but it does not. see how the top of the sand is dug out into deep waves and pits, filled up with gravel. and see, too, how over some of the gravel you get sand again, and then gravel again, and then sand again, till you cannot tell where one fairly begins and the other ends. why, here are little dots of gravel, six or eight feet down, in what looks the solid sand rock, yet the sand must have been opened somehow to put the gravel in. you say you have seen that before. you have seen the same curious twisting of the gravel and sand into each other on the top of farley hill, and in the new cutting on minley hill; and, best of all, in the railway cutting between ascot and sunningdale, where upon the top the white sand and gravel is arranged in red and brown waves, and festoons, and curlicues, almost like prince of wales's feathers. yes, that last is a beautiful section of ice-work; so beautiful, that i hope to have it photographed some day. now, how did ice do this? well, i was many a year before i found out that, and i dare say i never should have found it out for myself. a gentleman named trimmer, who, alas! is now dead, was, i believe, the first to find it out. he knew that along the coast of labrador, and other cold parts of north america, and on the shores, too, of the great river st. lawrence, the stranded icebergs, and the ice-foot, as it is called, which is continually forming along the freezing shores, grub and plough every tide into the mud and sand, and shove up before them, like a ploughshare, heaps of dirt; and that, too, the ice itself is full of dirt, of sand and stones, which it may have brought from hundreds of miles away; and that, as this ploughshare of dirty ice grubs onward, the nose of the plough is continually being broken off, and left underneath the mud; and that, when summer comes, and the ice melts, the mud falls back into the place where the ice had been, and covers up the gravel which was in the ice. so, what between the grubbing of the ice-plough into the mud, and the dirt which it leaves behind when it melts, the stones, and sand, and mud upon the shore are jumbled up into curious curved and twisted layers, exactly like those which mr. trimmer saw in certain gravel-pits. and when i first read about that, i said, "and exactly like what i have been seeing in every gravel-pit round here, and trying to guess how they could have been made by currents of water, and yet never could make any guess which would do." but after that it was all explained to me; and i said, "honour to the man who has let madam how teach him what she had been trying to teach me for fifteen years, while i was too stupid to learn it. now i am certain, as certain as i can be of any earthly thing, that the whole of these windsor forest flats were ages ago ploughed and harrowed over and over again, by ice-floes and icebergs drifting and stranding in a shallow sea." and if you say, my dear child, as some people will say, that it is like building a large house upon a single brick to be sure that there was an iceberg sea here, just because i see a few curlicues in the gravel and sand--then i must tell you that there are sometimes--not often, but sometimes--pages in madam how's book in which one single letter tells you as much as a whole chapter; in which if you find one little fact, and know what it really means, it makes you certain that a thousand other great facts have happened. you may be astonished: but you cannot deny your own eyes, and your own common sense. you feel like robinson crusoe when, walking along the shore of his desert island, he saw for the first time the print of a man's foot in the sand. how it could have got there without a miracle he could not dream. but there it was. one footprint was as good as the footprints of a whole army would have been. a man had been there; and more men might come. and in fear of the savages--and if you have read robinson crusoe you know how just his fears were--he went home trembling and loaded his muskets, and barricaded his cave, and passed sleepless nights watching for the savages who might come, and who came after all. and so there are certain footprints in geology which there is no mistaking; and the prints of the ice-plough are among them. for instance:--when they were trenching the new plantation close to wellington college station, the men turned up out of the ground a great many sarsden stones; that is, pieces of hard sugary sand, such as stonehenge is made of. and when i saw these i said, "i suspect these were brought here by icebergs:" but i was not sure, and waited. as the men dug on, they dug up a great many large flints, with bottle-green coats. "now," i said, "i am sure. for i know where these flints must have come from." and for reasons which would be too long to tell you here, i said, "some time or other, icebergs have been floating northward from the hog's back over aldershot and farnborough, and have been trying to get into the vale of thames by the slope at wellington college station; and they have stranded, and dropped these flints." and i am so sure of that, that if i found myself out wrong after all i should be at my wit's end; for i should know that i was wrong about a hundred things besides. or again, if you ever go up deeside in scotland, towards balmoral, and turn up glen muick, towards alt-na-guisach, of which you may see a picture in the queen's last book, you will observe standing on your right hand, just above birk hall, three pretty rounded knolls, which they call the coile hills. you may easily know them by their being covered with beautiful green grass instead of heather. that is because they are made of serpentine or volcanic rock, which (as you have seen) often cuts into beautiful red and green marble; and which also carries a very rich soil because it is full of magnesia. if you go up those hills, you get a glorious view--the mountains sweeping round you where you stand, up to the top of lochnagar, with its bleak walls a thousand feet perpendicular, and gullies into which the sun never shines, and round to the dark fir forests of the ballochbuie. that is the arc of the bow; and the cord of the bow is the silver dee, more than a thousand feet below you; and in the centre of the cord, where the arrow would be fitted in, stands balmoral, with its castle, and its gardens, and its park, and pleasant cottages and homesteads all around. and when you have looked at the beautiful amphitheatre of forest at your feet, and looked too at the great mountains to the westward, and benaun, and benna-buird and benna- muicdhui, with their bright patches of eternal snow, i should advise you to look at the rock on which you stand, and see what you see there. and you will see that on the side of the coiles towards lochnagar, and between the knolls of them, are scattered streams, as it were, of great round boulder stones--which are not serpentine, but granite from the top of lochnagar, five miles away. and you will see that the knolls of serpentine rock, or at least their backs and shoulders towards lochnagar, are all smoothed and polished till they are as round as the backs of sheep, "roches moutonnees," as the french call ice-polished rocks; and then, if you understand what that means, you will say, as i said, "i am perfectly certain that this great basin between me and lochnagar, which is now feet deep of empty air was once filled up with ice to the height of the hills on which i stand--about feet high--and that that ice ran over into glen muick, between these pretty knolls, and covered the ground where birk hall now stands." and more:--when you see growing on those knolls of serpentine a few pretty little alpine plants, which have no business down there so low, you will have a fair right to say, as i said, "the seeds of these plants were brought by the ice ages and ages since from off the mountain range of lochnagar, and left here, nestling among the rocks, to found a fresh colony, far from their old mountain home." if i could take you with me up to scotland,--take you, for instance, along the tay, up the pass of dunkeld, or up strathmore towards aberdeen, or up the dee towards braemar,--i could show you signs, which cannot be mistaken, of the time when scotland was, just like spitzbergen or like greenland now, covered in one vast sheet of snow and ice from year's end to year's end; when glaciers were ploughing out its valleys, icebergs were breaking off the icy cliffs and floating out to sea; when not a bird, perhaps, was to be seen save sea-fowl, not a plant upon the rocks but a few lichens, and alpine saxifrages, and such like--desolation and cold and lifeless everywhere. that ice-time went on for ages and for ages; and yet it did not go on in vain. through it madam how was ploughing down the mountains of scotland to make all those rich farms which stretch from the north side of the frith of forth into sutherlandshire. i could show you everywhere the green banks and knolls of earth, which scotch people call "kames" and "tomans"--perhaps brought down by ancient glaciers, or dropped by ancient icebergs--now so smooth and green through summer and through winter, among the wild heath and the rough peat-moss, that the old scots fancied, and i dare say scotch children fancy still, fairies dwelt inside. if you laid your ear against the mounds, you might hear the fairy music, sweet and faint, beneath the ground. if you watched the mound at night, you might see the fairies dancing the turf short and smooth, or riding out on fairy horses, with green silk clothes and jingling bells. but if you fell asleep upon the mounds, the fairy queen came out and carried you for seven years into fairyland, till you awoke again in the same place, to find all changed around you, and yourself grown thin and old. these are all dreams and fancies--untrue, not because they are too strange and wonderful, but because they are not strange and wonderful enough: for more wonderful sure than any fairy tale it is, that madam how should make a rich and pleasant land by the brute force of ice. and were there any men and women in that old age of ice? that is a long story, and a dark one too; we will talk of it next time. chapter vi--the true fairy tale you asked if there were men in england when the country was covered with ice and snow. look at this, and judge for yourself. what is it? a piece of old mortar? yes. but mortar which was made madam how herself, and not by any man. and what is in it? a piece of flint and some bits of bone. but look at that piece of flint. it is narrow, thin, sharp-edged: quite different in shape from any bit of flint which you or i ever saw among the hundreds of thousands of broken bits of gravel which we tread on here all day long; and here are some more bits like it, which came from the same place--all very much the same shape, like rough knives or razor blades; and here is a core of flint, the remaining part of a large flint, from which, as you may see, blades like those have been split off. those flakes of flint, my child, were split off by men; even your young eyes ought to be able to see that. and here are other pieces of flint--pear-shaped, but flattened, sharp at one end and left rounded at the other, which look like spear-heads, or arrow-heads, or pointed axes, or pointed hatchets--even your young eyes can see that these must have been made by man. and they are, i may tell you, just like the tools of flint, or of obsidian, which is volcanic glass, and which savages use still where they have not iron. there is a great obsidian knife, you know, in a house in this very parish, which came from mexico; and your eye can tell you how like it is to these flint ones. but these flint tools are very old. if you crack a fresh flint, you will see that its surface is gray, and somewhat rough, so that it sticks to your tongue. these tools are smooth and shiny: and the edges of some of them are a little rubbed from being washed about in gravel; while the iron in the gravel has stained them reddish, which it would take hundreds and perhaps thousands of years to do. there are little rough markings, too, upon some of them, which, if you look at through a magnifying glass, are iron, crystallised into the shape of little sea- weeds and trees--another sign that they are very very old. and what is more, near the place where these flint flakes come from there are no flints in the ground for hundreds of miles; so that men must have brought them there ages and ages since. and to tell you plainly, these are scrapers such as the esquimaux in north america still use to scrape the flesh off bones, and to clean the insides of skins. but did these people (savages perhaps) live when the country was icy cold? look at the bits of bone. they have been split, you see, lengthways; that, i suppose, was to suck the marrow out of them, as savages do still. but to what animal do the bones belong? that is the question, and one which i could not have answered you, if wiser men than i am could not have told me. they are the bones of reindeer--such reindeer as are now found only in lapland and the half-frozen parts of north america, close to the arctic circle, where they have six months day and six months night. you have read of laplanders, and how they drive reindeer in their sledges, and live upon reindeer milk; and you have read of esquimaux, who hunt seals and walrus, and live in houses of ice, lighted by lamps fed with the same blubber on which they feed themselves. i need not tell you about them. now comes the question--whence did these flints and bones come? they came out of a cave in dordogne, in the heart of sunny france,--far away to the south, where it is hotter every summer than it was here even this summer, from among woods of box and evergreen oak, and vineyards of rich red wine. in that warm land once lived savages, who hunted amid ice and snow the reindeer, and with the reindeer animals stranger still. and now i will tell you a fairy tale: to make you understand it at all i must put it in the shape of a tale. i call it a fairy tale, because it is so strange; indeed i think i ought to call it the fairy tale of all fairy tales, for by the time we get to the end of it i think it will explain to you how our forefathers got to believe in fairies, and trolls, and elves, and scratlings, and all strange little people who were said to haunt the mountains and the caves. well, once upon a time, so long ago that no man can tell when, the land was so much higher, that between england and ireland, and, what is more, between england and norway, was firm dry land. the country then must have looked--at least we know it looked so in norfolk--very like what our moors look like here. there were forests of scotch fir, and of spruce too, which is not wild in england now, though you may see plenty in every plantation. there were oaks and alders, yews and sloes, just as there are in our woods now. there was buck-bean in the bogs, as there is in larmer's and heath pond; and white and yellow water-lilies, horn-wort, and pond-weeds, just as there are now in our ponds. there were wild horses, wild deer, and wild oxen, those last of an enormous size. there were little yellow roe-deer, which will not surprise you, for there are hundreds and thousands in scotland to this day; and, as you know, they will thrive well enough in our woods now. there were beavers too: but that must not surprise you, for there were beavers in south wales long after the norman conquest, and there are beavers still in the mountain glens of the south-east of france. there were honest little water-rats too, who i dare say sat up on their hind legs like monkeys, nibbling the water-lily pods, thousands of years ago, as they do in our ponds now. well, so far we have come to nothing strange: but now begins the fairy tale. mixed with all these animals, there wandered about great herds of elephants and rhinoceroses; not smooth-skinned, mind, but covered with hair and wool, like those which are still found sticking out of the everlasting ice cliffs, at the mouth of the lena and other siberian rivers, with the flesh, and skin, and hair so fresh upon them, that the wild wolves tear it off, and snarl and growl over the carcase of monsters who were frozen up thousands of years ago. and with them, stranger still, were great hippopotamuses; who came, perhaps, northward in summer time along the sea-shore and down the rivers, having spread hither all the way from africa; for in those days, you must understand, sicily, and italy, and malta--look at your map--were joined to the coast of africa: and so it may be was the rock of gibraltar itself; and over the sea where the straits of gibraltar now flow was firm dry land, over which hyaenas and leopards, elephants and rhinoceroses ranged into spain; for their bones are found at this day in the gibraltar caves. and this is the first chapter of my fairy tale. now while all this was going on, and perhaps before this began, the climate was getting colder year by year--we do not know how; and, what is more, the land was sinking; and it sank so deep that at last nothing was left out of the water but the tops of the mountains in ireland, and scotland, and wales. it sank so deep that it left beds of shells belonging to the arctic regions nearly two thousand feet high upon the mountain side. and so "it grew wondrous cold, and ice mast-high came floating by, as green as emerald." but there were no masts then to measure the icebergs by, nor any ship nor human being there. all we know is that the icebergs brought with them vast quantities of mud, which sank to the bottom, and covered up that pleasant old forest-land in what is called boulder-clay; clay full of bits of broken rock, and of blocks of stone so enormous, that nothing but an iceberg could have carried them. so all the animals were drowned or driven away, and nothing was left alive perhaps, except a few little hardy plants which clung about cracks and gullies in the mountain tops; and whose descendants live there still. that was a dreadful time; the worst, perhaps, of all the age of ice; and so ends the second chapter of my fairy tale. now for my third chapter. "when things come to the worst," says the proverb, "they commonly mend;" and so did this poor frozen and drowned land of england and france and germany, though it mended very slowly. the land began to rise out of the sea once more, and rose till it was perhaps as high as it had been at first, and hundreds of feet higher than it is now: but still it was very cold, covered, in scotland at least, with one great sea of ice and glaciers descending down into the sea, as i said when i spoke to you about the ice-plough. but as the land rose, and grew warmer too, while it rose, the wild beasts who had been driven out by the great drowning came gradually back again. as the bottom of the old icy sea turned into dry land, and got covered with grasses, and weeds, and shrubs once more, elephants, rhinoceroses, hippopotamuses, oxen--sometimes the same species, sometimes slightly different ones--returned to france, and then to england (for there was no british channel then to stop them); and with them came other strange animals, especially the great irish elk, as he is called, as large as the largest horse, with horns sometimes ten feet across. a pair of those horns with the skull you have seen yourself, and can judge what a noble animal he must have been. enormous bears came too, and hyaenas, and a tiger or lion (i cannot say which), as large as the largest bengal tiger now to be seen in india. and in those days--we cannot, of course, exactly say when--there came--first i suppose into the south and east of france, and then gradually onward into england and scotland and ireland--creatures without any hair to keep them warm, or scales to defend them, without horns or tusks to fight with, or teeth to worry and bite; the weakest you would have thought of the beasts, and yet stronger than all the animals, because they were men, with reasonable souls. whence they came we cannot tell, nor why; perhaps from mere hunting after food, and love of wandering and being independent and alone. perhaps they came into that icy land for fear of stronger and cleverer people than themselves; for we have no proof, my child, none at all, that they were the first men that trod this earth. but be that as it may, they came; and so cunning were these savage men, and so brave likewise, though they had no iron among them, only flint and sharpened bones, yet they contrived to kill and eat the mammoths, and the giant oxen, and the wild horses, and the reindeer, and to hold their own against the hyaenas, and tigers, and bears, simply because they had wits, and the dumb animals had none. and that is the strangest part to me of all my fairy tale. for what a man's wits are, and why he has them, and therefore is able to invent and to improve, while even the cleverest ape has none, and therefore can invent and improve nothing, and therefore cannot better himself, but must remain from father to son, and father to son again, a stupid, pitiful, ridiculous ape, while men can go on civilising themselves, and growing richer and more comfortable, wiser and happier, year by year--how that comes to pass, i say, is to me a wonder and a prodigy and a miracle, stranger than all the most fantastic marvels you ever read in fairy tales. you may find the flint weapons which these old savages used buried in many a gravel-pit up and down france and the south of england; but you will find none here, for the gravel here was made (i am told) at the beginning of the ice-time, before the north of england sunk into the sea, and therefore long, long before men came into this land. but most of their remains are found in caves which water has eaten out of the limestone rocks, like that famous cave of kent's hole at torquay. in it, and in many another cave, lie the bones of animals which the savages ate, and cracked to get the marrow out of them, mixed up with their flint-weapons and bone harpoons, and sometimes with burnt ashes and with round stones, used perhaps to heat water, as savages do now, all baked together into a hard paste or breccia by the lime. these are in the water, and are often covered with a floor of stalagmite which has dripped from the roof above and hardened into stone. of these caves and their beautiful wonders i must tell you another day. we must keep now to our fairy tale. but in these caves, no doubt, the savages lived; for not only have weapons been found in them, but actually drawings scratched (i suppose with flint) on bone or mammoth ivory--drawings of elk, and bull, and horse, and ibex--and one, which was found in france, of the great mammoth himself, the woolly elephant, with a mane on his shoulders like a lion's mane. so you see that one of the earliest fancies of this strange creature, called man, was to draw, as you and your schoolfellows love to draw, and copy what you see, you know not why. remember that. you like to draw; but why you like it neither you nor any man can tell. it is one of the mysteries of human nature; and that poor savage clothed in skins, dirty it may be, and more ignorant than you (happily) can conceive, when he sat scratching on ivory in the cave the figures of the animals he hunted, was proving thereby that he had the same wonderful and mysterious human nature as you--that he was the kinsman of every painter and sculptor who ever felt it a delight and duty to copy the beautiful works of god. sometimes, again, especially in denmark, these savages have left behind upon the shore mounds of dirt, which are called there "kjokken-moddings"--"kitchen-middens" as they would say in scotland, "kitchen-dirtheaps" as we should say here down south--and a very good name for them that is; for they are made up of the shells of oysters, cockles, mussels, and periwinkles, and other shore-shells besides, on which those poor creatures fed; and mingled with them are broken bones of beasts, and fishes, and birds, and flint knives, and axes, and sling stones; and here and there hearths, on which they have cooked their meals in some rough way. and that is nearly all we know about them; but this we know from the size of certain of the shells, and from other reasons which you would not understand, that these mounds were made an enormous time ago, when the water of the baltic sea was far more salt than it is now. but what has all this to do with my fairy tale? this:-- suppose that these people, after all, had been fairies? i am in earnest. of course, i do not mean that these folk could make themselves invisible, or that they had any supernatural powers--any more, at least, than you and i have--or that they were anything but savages; but this i do think, that out of old stories of these savages grew up the stories of fairies, elves, and trolls, and scratlings, and cluricaunes, and ogres, of which you have read so many. when stronger and bolder people, like the irish, and the highlanders of scotland, and the gauls of france, came northward with their bronze and iron weapons; and still more, when our own forefathers, the germans and the norsemen, came, these poor little savages with their flint arrows and axes, were no match for them, and had to run away northward, or to be all killed out; for people were fierce and cruel in those old times, and looked on every one of a different race from themselves as a natural enemy. they had not learnt--alas! too many have not learned it yet--that all men are brothers for the sake of jesus christ our lord. so these poor savages were driven out, till none were left, save the little lapps up in the north of norway, where they live to this day. but stories of them, and of how they dwelt in caves, and had strange customs, and used poisoned weapons, and how the elf-bolts (as their flint arrow-heads are still called) belonged to them, lingered on, and were told round the fire on winter nights and added to, and played with half in fun, till a hundred legends sprang up about them, which used once to be believed by grown-up folk, but which now only amuse children. and because some of these savages were very short, as the lapps and esquimaux are now, the story grew of their being so small that they could make themselves invisible; and because others of them were (but probably only a few) very tall and terrible, the story grew that there were giants in that old world, like that famous gogmagog, whom brutus and his britons met (so old fables tell), when they landed first at plymouth, and fought him, and threw him over the cliff. ogres, too--of whom you read in fairy tales--i am afraid that there were such people once, even here in europe; strong and terrible savages, who ate human beings. of course, the legends and tales about them became ridiculous and exaggerated as they passed from mouth to mouth over the christmas fire, in the days when no one could read or write. but that the tales began by being true any one may well believe who knows how many cannibal savages there are in the world even now. i think that, if ever there was an ogre in the world, he must have been very like a certain person who lived, or was buried, in a cave in the neanderthal, between elberfeld and dusseldorf, on the lower rhine. the skull and bones which were found there (and which are very famous now among scientific men) belonged to a personage whom i should have been very sorry to meet, and still more to let you meet, in the wild forest; to a savage of enormous strength of limb (and i suppose of jaw) likewise "like an ape, with forehead villainous low," who could have eaten you if he would; and (i fear) also would have eaten you if he could. such savages may have lingered (i believe, from the old ballads and romances, that they did linger) for a long time in lonely forests and mountain caves, till they were all killed out by warriors who wore mail-armour and carried steel sword, and battle-axe, and lance. but had these people any religion? my dear child, we cannot know, and need not know. but we know this--that god beholds all the heathen. he fashions the hearts of them, and understandeth all their works. and we know also that he is just and good. these poor folks were, i doubt not, happy enough in their way; and we are bound to believe (for we have no proof against it), that most of them were honest and harmless enough likewise. of course, ogres and cannibals, and cruel and brutal persons (if there were any among them), deserved punishment--and punishment, i do not doubt, they got. but, of course, again, none of them knew things which you know; but for that very reason they were not bound to do many things which you are bound to do. for those to whom little is given, of them shall little be required. what their religion was like, or whether they had any religion at all, we cannot tell. but this we can tell, that known unto god are all his works from the creation of the world; and that his mercy is over all his works, and he hateth nothing that he has made. these men and women, whatever they were, were god's work; and therefore we may comfort ourselves with the certainty that, whether or not they knew god, god knew them. and so ends my fairy tale. but is it not a wonderful tale? more wonderful, if you will think over it, than any story invented by man. but so it always is. "truth," wise men tell us, "is stranger than fiction." even a child like you will see that it must be so, if you will but recollect who makes fiction, and who makes facts. man makes fiction: he invents stories, pretty enough, fantastical enough. but out of what does he make them up? out of a few things in this great world which he has seen, and heard, and felt, just as he makes up his dreams. but who makes truth? who makes facts? who, but god? then truth is as much larger than fiction, as god is greater than man; as much larger as the whole universe is larger than the little corner of it that any man, even the greatest poet or philosopher, can see; and as much grander, and as much more beautiful, and as much more strange. for one is the whole, and the other is one, a few tiny scraps of the whole. the one is the work of god; the other is the work of man. be sure that no man can ever fancy anything strange, unexpected, and curious, without finding if he had eyes to see, a hundred things around his feet more strange, more unexpected, more curious, actually ready-made already by god. you are fond of fairy tales, because they are fanciful, and like your dreams. my dear child, as your eyes open to the true fairy tale which madam how can tell you all day long, nursery stories will seem to you poor and dull. all those feelings in you which your nursery tales call out,--imagination, wonder, awe, pity, and i trust too, hope and love--will be called out, i believe, by the tale of all tales, the true "marchen allen marchen," so much more fully and strongly and purely, that you will feel that novels and story-books are scarcely worth your reading, as long as you can read the great green book, of which every bud is a letter, and every tree a page. wonder if you will. you cannot wonder too much. that you might wonder all your life long, god put you into this wondrous world, and gave you that faculty of wonder which he has not given to the brutes; which is at once the mother of sound science, and a pledge of immortality in a world more wondrous even than this. but wonder at the right thing, not at the wrong; at the real miracles and prodigies, not at the sham. wonder not at the world of man. waste not your admiration, interest, hope on it, its pretty toys, gay fashions, fine clothes, tawdry luxuries, silly amusements. wonder at the works of god. you will not, perhaps, take my advice yet. the world of man looks so pretty, that you will needs have your peep at it, and stare into its shop windows; and if you can, go to a few of its stage plays, and dance at a few of its balls. ah--well--after a wild dream comes an uneasy wakening; and after too many sweet things, comes a sick headache. and one morning you will awake, i trust and pray, from the world of man to the world of god, and wonder where wonder is due, and worship where worship is due. you will awake like a child who has been at a pantomime over night, staring at the "fairy halls," which are all paint and canvas; and the "dazzling splendours," which are gas and oil; and the "magic transformations," which are done with ropes and pulleys; and the "brilliant elves," who are poor little children out of the next foul alley; and the harlequin and clown, who through all their fun are thinking wearily over the old debts which they must pay, and the hungry mouths at home which they must feed: and so, having thought it all wondrously glorious, and quite a fairy land, slips tired and stupid into bed, and wakes next morning to see the pure light shining in through the delicate frost-lace on the window-pane, and looks out over fields of virgin snow, and watches the rosy dawn and cloudless blue, and the great sun rising to the music of cawing rooks and piping stares, and says, "this is the true wonder. this is the true glory. the theatre last night was the fairy land of man; but this is the fairy land of god." chapter vii--the chalk-carts what do you want to know about next? more about the caves in which the old savages lived,--how they were made, and how the curious things inside them got there, and so forth. well, we will talk about that in good time: but now--what is that coming down the hill? oh, only some chalk-carts. only some chalk-carts? it seems to me that these chalk-carts are the very things we want; that if we follow them far enough--i do not mean with our feet along the public road, but with our thoughts along a road which, i am sorry to say, the public do not yet know much about--we shall come to a cave, and understand how a cave is made. meanwhile, do not be in a hurry to say, "only a chalk-cart," or only a mouse, or only a dead leaf. chalk-carts, like mice, and dead leaves, and most other matters in the universe are very curious and odd things in the eyes of wise and reasonable people. whenever i hear young men saying "only" this and "only" that, i begin to suspect them of belonging, not to the noble army of sages--much less to the most noble army of martyrs,--but to the ignoble army of noodles, who think nothing interesting or important but dinners, and balls, and races, and back-biting their neighbours; and i should be sorry to see you enlisting in that regiment when you grow up. but think--are not chalk-carts very odd and curious things? i think they are. to my mind, it is a curious question how men ever thought of inventing wheels; and, again, when they first thought of it. it is a curious question, too, how men ever found out that they could make horses work for them, and so began to tame them, instead of eating them, and a curious question (which i think we shall never get answered) when the first horse-tamer lived, and in what country. and a very curious, and, to me, a beautiful sight it is, to see those two noble horses obeying that little boy, whom they could kill with a single kick. but, beside all this, there is a question, which ought to be a curious one to you (for i suspect you cannot answer it)--why does the farmer take the trouble to send his cart and horses eight miles and more, to draw in chalk from odiham chalk-pit? oh, he is going to put it on the land, of course. they are chalking the bit at the top of the next field, where the copse was grubbed. but what good will he do by putting chalk on it? chalk is not rich and fertile, like manure, it is altogether poor, barren stuff: you know that, or ought to know it. recollect the chalk cuttings and banks on the railway between basingstoke and winchester--how utterly barren they are. though they have been open these thirty years, not a blade of grass, hardly a bit of moss, has grown on them, or will grow, perhaps, for centuries. come, let us find out something about the chalk before we talk about the caves. the chalk is here, and the caves are not; and "learn from the thing that lies nearest you" is as good a rule as "do the duty which lies nearest you." let us come into the grubbed bit, and ask the farmer--there he is in his gig. well, old friend, and how are you? here is a little boy who wants to know why you are putting chalk on your field. does he then? if he ever tries to farm round here, he will have to learn for his first rule--no chalk, no wheat. but why? why, is more than i can tell, young squire. but if you want to see how it comes about, look here at this freshly-grubbed land--how sour it is. you can see that by the colour of it--some black, some red, some green, some yellow, all full of sour iron, which will let nothing grow. after the chalk has been on it a year or two, those colours will have all gone out of it; and it will turn to a nice wholesome brown, like the rest of the field; and then you will know that the land is sweet, and fit for any crop. now do you mind what i tell you, and then i'll tell you something more. we put on the chalk because, beside sweetening the land, it will hold water. you see, the land about here, though it is often very wet from springs, is sandy and hungry; and when we drain the bottom water out of it, the top water (that is, the rain) is apt to run through it too fast: and then it dries and burns up; and we get no plant of wheat, nor of turnips either. so we put on chalk to hold water, and keep the ground moist. but how can these lumps of chalk hold water? they are not made like cups. no: but they are made like sponges, which serves our turn better still. just take up that lump, young squire, and you'll see water enough in it, or rather looking out of it, and staring you in the face. why! one side of the lump is all over thick ice. so it is. all that water was inside the chalk last night, till it froze. and then it came squeezing out of the holes in the chalk in strings, as you may see it if you break the ice across. now you may judge for yourself how much water a load of chalk will hold, even on a dry summer's day. and now, if you'll excuse me, sir, i must be off to market. was it all true that the farmer said? quite true, i believe. he is not a scientific man--that is, he does not know the chemical causes of all these things; but his knowledge is sound and useful, because it comes from long experience. he and his forefathers, perhaps for a thousand years and more, have been farming this country, reading madam how's books with very keen eyes, experimenting and watching, very carefully and rationally; making mistakes often, and failing and losing their crops and their money; but learning from their mistakes, till their empiric knowledge, as it is called, helps them to grow sometimes quite as good crops as if they had learned agricultural chemistry. what he meant by the chalk sweetening the land you would not understand yet, and i can hardly tell you; for chemists are not yet agreed how it happens. but he was right; and right, too, what he told you about the water inside the chalk, which is more important to us just now; for, if we follow it out, we shall surely come to a cave at last. so now for the water in the chalk. you can see now why the chalk-downs at winchester are always green, even in the hottest summer: because madam how has put under them her great chalk sponge. the winter rains soak into it; and the summer heat draws that rain out of it again as invisible steam, coming up from below, to keep the roots of the turf cool and moist under the blazing sun. you love that short turf well. you love to run and race over the downs with your butterfly-net and hunt "chalk-hill blues," and "marbled whites," and "spotted burnets," till you are hot and tired; and then to sit down and look at the quiet little old city below, with the long cathedral roof, and the tower of st. cross, and the gray old walls and buildings shrouded by noble trees, all embosomed among the soft rounded lines of the chalk-hills; and then you begin to feel very thirsty, and cry, "oh, if there were but springs and brooks in the downs, as there are at home!" but all the hollows are as dry as the hill tops. there is not a brook, or the mark of a watercourse, in one of them. you are like the ancient mariner in the poem, with "water, water, every where, nor any drop to drink." to get that you must go down and down, hundreds of feet, to the green meadows through which silver itchen glides toward the sea. there you stand upon the bridge, and watch the trout in water so crystal-clear that you see every weed and pebble as if you looked through air. if ever there was pure water, you think, that is pure. is it so? drink some. wash your hands in it and try--you feel that the water is rough, hard (as they call it), quite different from the water at home, which feels as soft as velvet. what makes it so hard? because it is full of invisible chalk. in every gallon of that water there are, perhaps, fifteen grains of solid chalk, which was once inside the heart of the hills above. day and night, year after year, the chalk goes down to the sea; and if there were such creatures as water-fairies--if it were true, as the old greeks and romans thought, that rivers were living things, with a nymph who dwelt in each of them, and was its goddess or its queen--then, if your ears were opened to hear her, the nymph of itchen might say to you-- so child, you think that i do nothing but, as your sister says when she sings mr. tennyson's beautiful song, "i chatter over stony ways, in little sharps and trebles, i bubble into eddying bays, i babble on the pebbles." yes. i do that: and i love, as the nymphs loved of old, men who have eyes to see my beauty, and ears to discern my song, and to fit their own song to it, and tell how "'i wind about, and in and out, with here a blossom sailing, and here and there a lusty trout, and here and there a grayling, "'and here and there a foamy flake upon me, as i travel with many a silvery waterbreak above the golden gravel, "'and draw them all along, and flow to join the brimming river, for men may come and men may go, but i go on for ever.'" yes. that is all true: but if that were all, i should not be let to flow on for ever, in a world where lady why rules, and madam how obeys. i only exist (like everything else, from the sun in heaven to the gnat which dances in his beam) on condition of working, whether we wish it or not, whether we know it or not. i am not an idle stream, only fit to chatter to those who bathe or fish in my waters, or even to give poets beautiful fancies about me. you little guess the work i do. for i am one of the daughters of madam how, and, like her, work night and day, we know not why, though lady why must know. so day by day, and night by night, while you are sleeping (for i never sleep), i carry, delicate and soft as i am, a burden which giants could not bear: and yet i am never tired. every drop of rain which the south-west wind brings from the west indian seas gives me fresh life and strength to bear my burden; and it has need to do so; for every drop of rain lays a fresh burden on me. every root and weed which grows in every field; every dead leaf which falls in the highwoods of many a parish, from the grange and woodmancote round to farleigh and preston, and so to brighton and the alresford downs;--ay, every atom of manure which the farmers put on the land--foul enough then, but pure enough before it touches me--each of these, giving off a tiny atom of what men call carbonic acid, melts a tiny grain of chalk, and helps to send it down through the solid hill by one of the million pores and veins which at once feed and burden my springs. ages on ages i have worked on thus, carrying the chalk into the sea. and ages on ages, it may be, i shall work on yet; till i have done my work at last, and levelled the high downs into a flat sea-shore, with beds of flint gravel rattling in the shallow waves. she might tell you that; and when she had told you, you would surely think of the clumsy chalk-cart rumbling down the hill, and then of the graceful stream, bearing silently its invisible load of chalk; and see how much more delicate and beautiful, as well as vast and wonderful, madam how's work is than that of man. but if you asked the nymph why she worked on for ever, she could not tell you. for like the nymphs of old, and the hamadryads who lived, in trees, and undine, and the little sea-maiden, she would have no soul; no reason; no power to say why. it is for you, who are a reasonable being, to guess why: or at least listen to me if i guess for you, and say, perhaps--i can only say perhaps--that chalk may be going to make layers of rich marl in the sea between england and france; and those marl-beds may be upheaved and grow into dry land, and be ploughed, and sowed, and reaped by a wiser race of men, in a better-ordered world than this: or the chalk may have even a nobler destiny before it. that may happen to it, which has happened already to many a grain of lime. it may be carried thousands of miles away to help in building up a coral reef (what that is i must tell you afterwards). that coral reef may harden into limestone beds. those beds may be covered up, pressed, and, it may be, heated, till they crystallise into white marble: and out of it fairer statues be carved, and grander temples built, than the world has ever yet seen. and if that is not the reason why the chalk is being sent into the sea, then there is another reason, and probably a far better one. for, as i told you at first, lady why's intentions are far wiser and better than our fancies; and she--like him whom she obeys--is able to do exceeding abundantly, beyond all that we can ask or think. but you will say now that we have followed the chalk-cart a long way, without coming to the cave. you are wrong. we have come to the very mouth of the cave. all we have to do is to say--not "open sesame," like ali baba in the tale of the forty thieves--but some word or two which madam why will teach us, and forthwith a hill will open, and we shall walk in, and behold rivers and cascades underground, stalactite pillars and stalagmite statues, and all the wonders of the grottoes of adelsberg, antiparos, or kentucky. am i joking? yes, and yet no; for you know that when i joke i am usually most in earnest. at least, i am now. but there are no caves in chalk? no, not that i ever heard of. there are, though, in limestone, which is only a harder kind of chalk. madam how could turn this chalk into hard limestone, i believe, even now; and in more ways than one: but in ways which would not be very comfortable or profitable for us southern folk who live on it. i am afraid that--what between squeezing and heating--she would flatten us all out into phosphatic fossils, about an inch thick; and turn winchester city into a "breccia" which would puzzle geologists a hundred thousand years hence. so we will hope that she will leave our chalk downs for the itchen to wash gently away, while we talk about caves, and how madam how scoops them out by water underground, just in the same way, only more roughly, as she melts the chalk. suppose, then, that these hills, instead of being soft, spongy chalk, were all hard limestone marble, like that of which the font in the church is made. then the rainwater, instead of sinking through the chalk as now, would run over the ground down-hill, and if it came to a crack (a fault, as it is called) it would run down between the rock; and as it ran it would eat that hole wider and wider year by year, and make a swallow- hole--such as you may see in plenty if you ever go up whernside, or any of the high hills in yorkshire--unfathomable pits in the green turf, in which you may hear the water tinkling and trickling far, far underground. and now, before we go a step farther, you may understand, why the bones of animals are so often found in limestone caves. down such swallow-holes how many beasts must fall: either in hurry and fright, when hunted by lions and bears and such cruel beasts; or more often still in time of snow, when the holes are covered with drift; or, again, if they died on the open hill-sides, their bones might be washed in, in floods, along with mud and stones, and buried with them in the cave below; and beside that, lions and bears and hyaenas might live in the caves below, as we know they did in some caves, and drag in bones through the caves' mouths; or, again, savages might live in that cave, and bring in animals to eat, like the wild beasts; and so those bones might be mixed up, as we know they were, with things which the savages had left behind--like flint tools or beads; and then the whole would be hardened, by the dripping of the limestone water, into a paste of breccia just like this in my drawer. but the bones of the savages themselves you would seldom or never find mixed in it--unless some one had fallen in by accident from above. and why? (for there is a why? to that question: and not merely a how?) simply because they were men; and because god has put into the hearts of all men, even of the lowest savages, some sort of reverence for those who are gone; and has taught them to bury, or in some other way take care of, their bones. but how is the swallow-hole sure to end in a cave? because it cannot help making a cave for itself if it has time. think: and you will see that it must be so. for that water must run somewhere; and so it eats its way out between the beds of the rock, making underground galleries, and at last caves and lofty halls. for it always eats, remember, at the bottom of its channel, leaving the roof alone. so it eats, and eats, more in some places and less in others, according as the stone is harder or softer, and according to the different direction of the rock-beds (what we call their dip and strike); till at last it makes one of those wonderful caverns about which you are so fond of reading--such a cave as there actually is in the rocks of the mountain of whernside, fed by the swallow-holes around the mountain-top; a cave hundreds of yards long, with halls, and lakes, and waterfalls, and curtains and festoons of stalactite which have dripped from the roof, and pillars of stalagmite which have been built up on the floor below. these stalactites (those tell me who have seen them) are among the most beautiful of all madam how's work; sometimes like branches of roses or of grapes; sometimes like statues; sometimes like delicate curtains, and i know not what other beautiful shapes. i have never seen them, i am sorry to say, and therefore i cannot describe them. but they are all made in the same way; just in the same way as those little straight stalactites which you may have seen hanging, like icicles, in vaulted cellars, or under the arches of a bridge. the water melts more lime than it can carry, and drops some of it again, making fresh limestone grain by grain as it drips from the roof above; and fresh limestone again where it splashes on the floor below: till if it dripped long enough, the stalactite hanging from above would meet the stalagmite rising from below, and join in one straight round white graceful shaft, which would seem (but only seem) to support the roof of the cave. and out of that cave--though not always out of the mouth of it--will run a stream of water, which seems to you clear as crystal, though it is actually, like the itchen at winchester, full of lime; so full of lime, that it makes beds of fresh limestone, which are called travertine--which you may see in italy, and greece, and asia minor: or perhaps it petrifies, as you call it, the weeds in its bed, like that dropping-well at knaresborough, of which you have often seen a picture. and the cause is this: the water is so full of lime, that it is forced to throw away some of it upon everything it touches, and so incrusts with stone--though it does not turn to stone--almost anything you put in it. you have seen, or ought to have seen, petrified moss and birds' nests and such things from knaresborough well: and now you know a little, though only a very little, of how the pretty toys are made. now if you can imagine for yourself (though i suppose a little boy cannot) the amount of lime which one of these subterranean rivers would carry away, gnawing underground centuries after centuries, day and night, summer and winter, then you will not be surprised at the enormous size of caverns which may be seen in different parts of the world--but always, i believe, in limestone rock. you would not be surprised (though you would admire them) at the caverns of adelsberg, in carniola (in the south of austria, near the top of the adriatic), which runs, i believe, for miles in length; and in the lakes of which, in darkness from its birth until its death, lives that strange beast, the proteus a sort of long newt which never comes to perfection--i suppose for want of the genial sunlight which makes all things grow. but he is blind; and more, he keeps all his life the same feathery gills which newts have when they are babies, and which we have so often looked at through the microscope, to see the blood-globules run round and round inside. you would not wonder, either, at the czirknitz lake, near the same place, which at certain times of the year vanishes suddenly through chasms under water, sucking the fish down with it; and after a certain time boils suddenly up again from the depths, bringing back with it the fish, who have been swimming comfortably all the time in a subterranean lake; and bringing back, too (and, extraordinary as this story is, there is good reason to believe it true), live wild ducks who went down small and unfledged, and come back full-grown and fat, with water-weeds and small fish in their stomachs, showing they have had plenty to feed on underground. but--and this is the strangest part of the story, if true--they come up unfledged just as they went down, and are moreover blind from having been so long in darkness. after a while, however, folks say their eyes get right, their feathers grow, and they fly away like other birds. neither would you be surprised (if you recollect that madam how is a very old lady indeed, and that some of her work is very old likewise) at that mammoth cave in kentucky, the largest cave in the known world, through which you may walk nearly ten miles on end, and in which a hundred miles of gallery have been explored already, and yet no end found to the cave. in it (the guides will tell you) there are " avenues, domes, cataracts, pits, and several rivers;" and if that fact is not very interesting to you (as it certainly is not to me) i will tell you something which ought to interest you: that this cave is so immensely old that various kinds of little animals, who have settled themselves in the outer parts of it, have had time to change their shape, and to become quite blind; so that blind fathers and mothers have blind children, generation after generation. there are blind rats there, with large shining eyes which cannot see--blind landcrabs, who have the foot-stalks of their eyes (you may see them in any crab) still left; but the eyes which should be on the top of them are gone. there are blind fish, too, in the cave, and blind insects; for, if they have no use for their eyes in the dark, why should madam how take the trouble to finish them off? one more cave i must tell you of, to show you how old some caves must be, and then i must stop; and that is the cave of caripe, in venezuela, which is the most northerly part of south america. there, in the face of a limestone cliff, crested with enormous flowering trees, and festooned with those lovely creepers of which you have seen a few small ones in hothouses, there opens an arch as big as the west front of winchester cathedral, and runs straight in like a cathedral nave for more than feet. out of it runs a stream; and along the banks of that stream, as far as the sunlight strikes in, grow wild bananas, and palms, and lords and ladies (as you call them), which are not, like ours, one foot, but many feet high. beyond that the cave goes on, with subterranean streams, cascades, and halls, no man yet knows how far. a friend of mine last year went in farther, i believe, than any one yet has gone; but, instead of taking indian torches made of bark and resin, or even torches made of spanish wax, such as a brave bishop of those parts used once when he went in farther than any one before him, he took with him some of that beautiful magnesium light which you have seen often here at home. and in one place, when he lighted up the magnesium, he found himself in a hall full feet high--higher far, that is, than the dome of st. paul's--and a very solemn thought it was to him, he said, that he had seen what no other human being ever had seen; and that no ray of light had ever struck on that stupendous roof in all the ages since the making of the world. but if he found out something which he did not expect, he was disappointed in something which he did expect. for the indians warned him of a hole in the floor which (they told him) was an unfathomable abyss. and lo and behold, when he turned the magnesium light upon it, the said abyss was just about eight feet deep. but it is no wonder that the poor indians with their little smoky torches should make such mistakes; no wonder, too, that they should be afraid to enter far into those gloomy vaults; that they should believe that the souls of their ancestors live in that dark cave; and that they should say that when they die they will go to the guacharos, as they call the birds that fly with doleful screams out of the cave to feed at night, and in again at daylight, to roost and sleep. now, it is these very guacharo birds which are to me the most wonderful part of the story. the indians kill and eat them for their fat, although they believe they have to do with evil spirits. but scientific men who have studied these birds will tell you that they are more wonderful than if all the indians' fancies about them were true. they are great birds, more than three feet across the wings, somewhat like owls, somewhat like cuckoos, somewhat like goatsuckers; but, on the whole, unlike anything in the world but themselves; and instead of feeding on moths or mice, they feed upon hard dry fruits, which they pick off the trees after the set of sun. and wise men will tell you, that in making such a bird as that, and giving it that peculiar way of life, and settling it in that cavern, and a few more caverns in that part of the world, and therefore in making the caverns ready for them to live in, madam how must have taken ages and ages, more than you can imagine or count. but that is among the harder lessons which come in the latter part of madam how's book. children need not learn them yet; and they can never learn them, unless they master her alphabet, and her short and easy lessons for beginners, some of which i am trying to teach you now. but i have just recollected that we are a couple of very stupid fellows. we have been talking all this time about chalk and limestone, and have forgotten to settle what they are, and how they were made. we must think of that next time. it will not do for us (at least if we mean to be scientific men) to use terms without defining them; in plain english, to talk about--we don't know what. chapter viii--madam how's two grandsons you want to know, then, what chalk is? i suppose you mean what chalk is made of? yes. that is it. that we can only help by calling in the help of a very great giant whose name is analysis. a giant? yes. and before we call for him i will tell you a very curious story about him and his younger brother, which is every word of it true. once upon a time, certainly as long ago as the first man, or perhaps the first rational being of any kind, was created, madam how had two grandsons. the elder is called analysis, and the younger synthesis. as for who their father and mother were, there have been so many disputes on that question that i think children may leave it alone for the present. for my part, i believe that they are both, like st. patrick, "gentlemen, and come of decent people;" and i have a great respect and affection for them both, as long as each keeps in his own place and minds his own business. now you must understand that, as soon as these two baby giants were born, lady why, who sets everything to do that work for which it is exactly fitted, set both of them their work. analysis was to take to pieces everything he found, and find out how it was made. synthesis was to put the pieces together again, and make something fresh out of them. in a word, analysis was to teach men science; and synthesis to teach them art. but because analysis was the elder, madam how commanded synthesis never to put the pieces together till analysis had taken them completely apart. and, my child, if synthesis had obeyed that rule of his good old grandmother's, the world would have been far happier, wealthier, wiser, and better than it is now. but synthesis would not. he grew up a very noble boy. he could carve, he could paint, he could build, he could make music, and write poems: but he was full of conceit and haste. whenever his elder brother tried to do a little patient work in taking things to pieces, synthesis snatched the work out of his hands before it was a quarter done, and began putting it together again to suit his own fancy, and, of course, put it together wrong. then he went on to bully his elder brother, and locked him up in prison, and starved him, till for many hundred years poor analysis never grew at all, but remained dwarfed, and stupid, and all but blind for want of light; while synthesis, and all the hasty conceited people who followed him, grew stout and strong and tyrannous, and overspread the whole world, and ruled it at their will. but the fault of all the work of synthesis was just this: that it would not work. his watches would not keep time, his soldiers would not fight, his ships would not sail, his houses would not keep the rain out. so every time he failed in his work he had to go to poor analysis in his dungeon, and bully him into taking a thing or two to pieces, and giving him a few sound facts out of them, just to go on with till he came to grief again, boasting in the meantime that he and not analysis had found out the facts. and at last he grew so conceited that he fancied he knew all that madam how could teach him, or lady why either, and that he understood all things in heaven and earth; while it was not the real heaven and earth that he was thinking of, but a sham heaven and a sham earth, which he had built up out of his guesses and his own fancies. and the more synthesis waxed in pride, and the more he trampled upon his poor brother, the more reckless he grew, and the more willing to deceive himself. if his real flowers would not grow, he cut out paper flowers, and painted them and said that they would do just as well as natural ones. if his dolls would not work, he put strings and wires behind them to make them nod their heads and open their eyes, and then persuaded other people, and perhaps half-persuaded himself, that they were alive. if the hand of his weather-glass went down, he nailed it up to insure a fine day, and tortured, burnt, or murdered every one who said it did not keep up of itself. and many other foolish and wicked things he did, which little boys need not hear of yet. but at last his punishment came, according to the laws of his grandmother, madam how, which are like the laws of the medes and persians, and alter not, as you and all mankind will sooner or later find; for he grew so rich and powerful that he grew careless and lazy, and thought about nothing but eating and drinking, till people began to despise him more and more. and one day he left the dungeon of analysis so ill guarded, that analysis got out and ran away. great was the hue and cry after him; and terribly would he have been punished had he been caught. but, lo and behold, folks had grown so disgusted with synthesis that they began to take the part of analysis. poor men hid him in their cottages, and scholars in their studies. and when war arose about him,--and terrible wars did arise,--good kings, wise statesmen, gallant soldiers, spent their treasure and their lives in fighting for him. all honest folk welcomed him, because he was honest; and all wise folk used him, for, instead of being a conceited tyrant like synthesis, he showed himself the most faithful, diligent, humble of servants, ready to do every man's work, and answer every man's questions. and among them all he got so well fed that he grew very shortly into the giant that he ought to have been all along; and was, and will be for many a year to come, perfectly able to take care of himself. as for poor synthesis, he really has fallen so low in these days, that one cannot but pity him. he now goes about humbly after his brother, feeding on any scraps that are thrown to him, and is snubbed and rapped over the knuckles, and told one minute to hold his tongue and mind his own business, and the next that he has no business at all to mind, till he has got into such a poor way that some folks fancy he will die, and are actually digging his grave already, and composing his epitaph. but they are trying to wear the bear's skin before the bear is killed; for synthesis is not dead, nor anything like it; and he will rise up again some day, to make good friends with his brother analysis, and by his help do nobler and more beautiful work than he has ever yet done in the world. so now analysis has got the upper hand; so much so that he is in danger of being spoilt by too much prosperity, as his brother was before him; in which case he too will have his fall; and a great deal of good it will do him. and that is the end of my story, and a true story it is. now you must remember, whenever you have to do with him, that analysis, like fire, is a very good servant, but a very bad master. for, having got his freedom only of late years or so, he is, like young men when they come suddenly to be their own masters, apt to be conceited, and to fancy that he knows everything, when really he knows nothing, and can never know anything, but only knows about things, which is a very different matter. indeed, nowadays he pretends that he can teach his old grandmother, madam how, not only how to suck eggs, but to make eggs into the bargain; while the good old lady just laughs at him kindly, and lets him run on, because she knows he will grow wiser in time, and learn humility by his mistakes and failures, as i hope you will from yours. however, analysis is a very clever young giant, and can do wonderful work as long as he meddles only with dead things, like this bit of lime. he can take it to pieces, and tell you of what things it is made, or seems to be made; and take them to pieces again, and tell you what each of them is made of; and so on, till he gets conceited, and fancies that he can find out some one thing of all things (which he calls matter), of which all other things are made; and some way of all ways (which he calls force), by which all things are made: but when he boasts in that way, old madam how smiles, and says, "my child, before you can say that, you must remember a hundred things which you are forgetting, and learn a hundred thousand things which you do not know;" and then she just puts her hand over his eyes, and master analysis begins groping in the dark, and talking the saddest nonsense. so beware of him, and keep him in his own place, and to his own work, or he will flatter you, and get the mastery of you, and persuade you that he can teach you a thousand things of which he knows no more than he does why a duck's egg never hatches into a chicken. and remember, if master analysis ever grows saucy and conceited with you, just ask him that last riddle, and you will shut him up at once. and why? because analysis can only explain to you a little about dead things, like stones--inorganic things as they are called. living things--organisms, as they are called--he cannot explain to you at all. when he meddles with them, he always ends like the man who killed his goose to get the golden eggs. he has to kill his goose, or his flower, or his insect, before he can analyse it; and then it is not a goose, but only the corpse of a goose; not a flower, but only the dead stuff of the flower. and therefore he will never do anything but fail, when he tries to find out the life in things. how can he, when he has to take the life out of them first? he could not even find out how a plum-pudding is made by merely analysing it. he might part the sugar, and the flour, and the suet; he might even (for he is very clever, and very patient too, the more honour to him) take every atom of sugar out of the flour with which it had got mixed, and every atom of brown colour which had got out of the plums and currants into the body of the pudding, and then, for aught i know, put the colouring matter back again into the plums and currants; and then, for aught i know, turn the boiled pudding into a raw one again,--for he is a great conjurer, as madam how's grandson is bound to be: but yet he would never find out how the pudding was made, unless some one told him the great secret which the sailors in the old story forgot--that the cook boiled it in a cloth. this is analysis's weak point--don't let it be yours--that in all his calculations he is apt to forget the cloth, and indeed the cook likewise. no doubt he can analyse the matter of things: but he will keep forgetting that he cannot analyse their form. do i mean their shape? no, my child; no. i mean something which makes the shape of things, and the matter of them likewise, but which folks have lost sight of nowadays, and do not seem likely to get sight of again for a few hundred years. so i suppose that you need not trouble your head about it, but may just follow the fashions as long as they last. about this piece of lime, however, analysis can tell us a great deal. and we may trust what he says, and believe that he understands what he says. why? think now. if you took your watch to pieces, you would probably spoil it for ever; you would have perhaps broken, and certainly mislaid, some of the bits; and not even a watchmaker could put it together again. you would have analysed the watch wrongly. but if a watchmaker took it to pieces then any other watchmaker could put it together again to go as well as ever, because they both understand the works, how they fit into each other, and what the use and the power of each is. its being put together again rightly would be a proof that it had been taken to pieces rightly. and so with master analysis. if he can take a thing to pieces so that his brother synthesis can put it together again, you may be sure that he has done his work rightly. now he can take a bit of chalk to pieces, so that it shall become several different things, none of which is chalk, or like chalk at all. and then his brother synthesis can put them together again, so that they shall become chalk, as they were before. he can do that very nearly, but not quite. there is, in every average piece of chalk, something which he cannot make into chalk again when he has once unmade it. what that is i will show you presently; and a wonderful tale hangs thereby. but first we will let analysis tell us what chalk is made of, as far as he knows. he will say--chalk is carbonate of lime. but what is carbonate of lime made of? lime and carbonic acid. and what is lime? the oxide of a certain metal, called calcium. what do you mean? that quicklime is a certain metal mixed with oxygen gas; and slacked lime is the same, mixed with water. so lime is a metal. what is a metal? nobody knows. and what is oxygen gas? nobody knows. well, analysis, stops short very soon. he does not seem to know much about the matter. nay, nay, you are wrong there. it is just "about the matter" that he does know, and knows a great deal, and very accurately; what he does not know is the matter itself. he will tell you wonderful things about oxygen gas--how the air is full of it, the water full of it, every living thing full of it; how it changes hard bright steel into soft, foul rust; how a candle cannot burn without it, or you live without it. but what it is he knows not. will he ever know? that is lady why's concern, and not ours. meanwhile he has a right to find out if he can. but what do you want to ask him next? what? oh! what carbonic acid is. he can tell you that. carbon and oxygen gas. but what is carbon? nobody knows. why, here is this stupid analysis at fault again. nay, nay, again. be patient with him. if he cannot tell you what carbon is, he can tell you what is carbon, which is well worth knowing. he will tell you, for instance, that every time you breathe or speak, what comes out of your mouth is carbonic acid; and that, if your breath comes on a bit of slacked lime, it will begin to turn it back into the chalk from which it was made; and that, if your breath comes on the leaves of a growing plant, that leaf will take the carbon out of it, and turn it into wood. and surely that is worth knowing,--that you may be helping to make chalk, or to make wood, every time you breathe. well; that is very curious. but now, ask him, what is carbon? and he will tell you, that many things are carbon. a diamond is carbon; and so is blacklead; and so is charcoal and coke, and coal in part, and wood in part. what? does analysis say that a diamond and charcoal are the same thing? yes. then his way of taking things to pieces must be a very clumsy one, if he can find out no difference between diamond and charcoal. well, perhaps it is: but you must remember that, though he is very old--as old as the first man who ever lived--he has only been at school for the last three hundred years or so. and remember, too, that he is not like you, who have some one else to teach you. he has had to teach himself, and find out for himself, and make his own tools, and work in the dark besides. and i think it is very much to his credit that he ever found out that diamond and charcoal were the same things. you would never have found it out for yourself, you will agree. no: but how did he do it? he taught a very famous chemist, lavoisier, about ninety years ago, how to burn a diamond in oxygen--and a very difficult trick that is; and lavoisier found that the diamond when burnt turned almost entirely into carbonic acid and water, as blacklead and charcoal do; and more, that each of them turned into the same quantity of carbonic acid, and so he knew, as surely as man can know anything, that all these things, however different to our eyes and fingers, are really made of the same thing,--pure carbon. but what makes them look and feel so different? that analysis does not know yet. perhaps he will find out some day; for he is very patient, and very diligent, as you ought to be. meanwhile, be content with him: remember that though he cannot see through a milestone yet, he can see farther into one than his neighbours. indeed his neighbours cannot see into a milestone at all, but only see the outside of it, and know things only by rote, like parrots, without understanding what they mean and how they are made. so now remember that chalk is carbonate of lime, and that it is made up of three things, calcium, oxygen, and carbon; and that therefore its mark is caco( ), in analysis's language, which i hope you will be able to read some day. but how is it that analysis and synthesis cannot take all this chalk to pieces, and put it together again? look here; what is that in the chalk? oh! a shepherd's crown, such as we often find in the gravel, only fresh and white. well; you know what that was once. i have often told you:--a live sea- egg, covered with prickles, which crawls at the bottom of the sea. well, i am sure that master synthesis could not put that together again: and equally sure that master analysis might spend ages in taking it to pieces, before he found out how it was made. and--we are lucky to-day, for this lower chalk to the south has very few fossils in it--here is something else which is not mere carbonate of lime. look at it. a little cockle, something like a wrinkled hazel-nut. no; that is no cockle. madam how invented that ages and ages before she thought of cockles, and the animal which lived inside that shell was as different from a cockle-animal as a sparrow is from a dog. that is a terebratula, a gentleman of a very ancient and worn-out family. he and his kin swarmed in the old seas, even as far back as the time when the rocks of the welsh mountains were soft mud; as you will know when you read that great book of sir roderick murchison's, _siluria_. but as the ages rolled on, they got fewer and fewer, these terebratulae; and now there are hardly any of them left; only six or seven sorts are left about these islands, which cling to stones in deep water; and the first time i dredged two of them out of loch fyne, i looked at them with awe, as on relics from another world, which had lasted on through unnumbered ages and changes, such as one's fancy could not grasp. but you will agree that, if master analysis took that shell to pieces, master synthesis would not be likely to put it together again; much less to put it together in the right way, in which madam how made it. and what was that? by making a living animal, which went on growing, that is, making itself; and making, as it grew, its shell to live in. synthesis has not found out yet the first step towards doing that; and, as i believe, he never will. but there would be no harm in his trying? of course not. let everybody try to do everything they fancy. even if they fail, they will have learnt at least that they cannot do it. but now--and this is a secret which you would never find out for yourself, at least without the help of a microscope--the greater part of this lump of chalk is made up of things which neither analysis can perfectly take to pieces, nor synthesis put together again. it is made of dead organisms, that is, things which have been made by living creatures. if you washed and brushed that chalk into powder, you would find it full of little things like the dentalina in this drawing, and many other curious forms. i will show you some under the microscope one day. they are the shells of animals called foraminifera, because the shells of some of them are full of holes, through which they put out tiny arms. so small they are and so many, that there may be, it is said, forty thousand of them in a bit of chalk an inch every way. in numbers past counting, some whole, some broken, some ground to the finest powder, they make up vast masses of england, which are now chalk downs; and in some foreign countries they make up whole mountains. part of the building stone of the great pyramid in egypt is composed, i am told, entirely of them. and how did they get into the chalk? ah! how indeed? let us think. the chalk must have been laid down at the bottom of a sea, because there are sea-shells in it. besides, we find little atomies exactly like these alive now in many seas; and therefore it is fair to suppose these lived in the sea also. besides, they were not washed into the chalk by any sudden flood. the water in which they settled must have been quite still, or these little delicate creatures would have been ground into powder--or rather into paste. therefore learned men soon made up their minds that these things were laid down at the bottom of a deep sea, so deep that neither wind, nor tide, nor currents could stir the everlasting calm. ah! it is worth thinking over, for it shows how shrewd a giant analysis is, and how fast he works in these days, now that he has got free and well fed;--worth thinking over, i say, how our notions about these little atomies have changed during the last forty years. we used to find them sometimes washed up among the sea-sand on the wild atlantic coast; and we were taught, in the days when old dr. turton was writing his book on british shells at bideford, to call them nautili, because their shells were like nautilus shells. men did not know then that the animal which lives in them is no more like a nautilus animal than it is like a cow. for a nautilus, you must know, is made like a cuttlefish, with eyes, and strong jaws for biting, and arms round them; and has a heart, and gills, and a stomach; and is altogether a very well-made beast, and, i suspect, a terrible tyrant to little fish and sea-slugs, just as the cuttlefish is. but the creatures which live in these little shells are about the least finished of madam how's works. they have neither mouth nor stomach, eyes nor limbs. they are mere live bags full of jelly, which can take almost any shape they like, and thrust out arms--or what serve for arms--through the holes in their shells, and then contract them into themselves again, as this globigerina does. what they feed on, how they grow, how they make their exquisitely-formed shells, whether, indeed, they are, strictly speaking, animals or vegetables, analysis has not yet found out. but when you come to read about them, you will find that they, in their own way, are just as wonderful and mysterious as a butterfly or a rose; and just as necessary, likewise, to madam how's work; for out of them, as i told you, she makes whole sheets of down, whole ranges of hills. no one knew anything, i believe, about them, save that two or three kinds of them were found in chalk, till a famous frenchman, called d'orbigny, just thirty years ago, told the world how he had found many beautiful fresh kinds; and, more strange still, that some of these kinds were still alive at the bottom of the adriatic, and of the harbour of alexandria, in egypt. then in a gentleman named edward forbes,--now with god--whose name will be for ever dear to all who love science, and honour genius and virtue,--found in the aegean sea "a bed of chalk," he said, "full of foraminifera, and shells of pteropods," forming at the bottom of the sea. and what are pteropods? what you might call sea-moths (though they are not really moths), which swim about on the surface of the water, while the right-whales suck them in tens of thousands into the great whalebone net which fringes their jaws. here are drawings of them. . limacina (on which the whales feed); and . hyalea, a lovely little thing in a glass shell, which lives in the mediterranean. but since then strange discoveries have been made, especially by the naval officers who surveyed the bottom of the great atlantic ocean before laying down the electric cable between ireland and america. and this is what they found: that at the bottom of the atlantic were vast plains of soft mud, in some places fathoms ( , feet) deep; that is, as deep as the alps are high. and more: they found out, to their surprise, that the oozy mud of the atlantic floor was made up almost entirely of just the same atomies as make up our chalk, especially globigerinas; that, in fact, a vast bed of chalk was now forming at the bottom of the atlantic, with living shells and sea-animals of the most brilliant colours crawling about on it in black darkness, and beds of sponges growing out of it, just as the sponges grew at the bottom of the old chalk ocean, and were all, generation after generation, turned into flints. and, for reasons which you will hardly understand, men are beginning now to believe that the chalk has never ceased to be made, somewhere or other, for many thousand years, ever since the winchester downs were at the bottom of the sea: and that "the globigerina-mud is not merely _a_ chalk formation, but a continuation of _the_ chalk formation, so _that we may be said to be still living in the age of chalk_." { } ah, my little man, what would i not give to see you, before i die, add one such thought as that to the sum of human knowledge! so there the little creatures have been lying, making chalk out of the lime in the sea-water, layer over layer, the young over the old, the dead over the living, year after year, age after age--for how long? who can tell? how deep the layer of new chalk at the bottom of the atlantic is, we can never know. but the layer of live atomies on it is not an inch thick, probably not a tenth of an inch. and if it grew a tenth of an inch a year, or even a whole inch, how many years must it have taken to make the chalk of our downs, which is in some parts feet thick? how many inches are there in feet? do that sum, and judge for yourself. one difference will be found between the chalk now forming at the bottom of the ocean, if it ever become dry land, and the chalk on which you tread on the downs. the new chalk will be full of the teeth and bones of whales--warm-blooded creatures, who suckle their young like cows, instead of laying eggs, like birds and fish. for there were no whales in the old chalk ocean; but our modern oceans are full of cachalots, porpoises, dolphins, swimming in shoals round any ship; and their bones and teeth, and still more their ear-bones, will drop to the bottom as they die, and be found, ages hence, in the mud which the live atomies make, along with wrecks of mighty ships "great anchors, heaps of pearl," and all that man has lost in the deep seas. and sadder fossils yet, my child, will be scattered on those white plains:-- "to them the love of woman hath gone down, dark roll their waves o'er manhood's noble head. o'er youth's bright locks, and beauty's flowing crown; yet shall they hear a voice, 'restore the dead.' earth shall reclaim her precious things from thee. give back the dead, thou sea!" chapter ix--the coral-reef now you want to know what i meant when i talked of a bit of lime going out to sea, and forming part of a coral island, and then of a limestone rock, and then of a marble statue. very good. then look at this stone. what a curious stone! did it come from any place near here? no. it came from near dudley, in staffordshire, where the soils are worlds on worlds older than they are here, though they were made in the same way as these and all other soils. but you are not listening to me. why, the stone is full of shells, and bits of coral; and what are these wonderful things coiled and tangled together, like the snakes in medusa's hair in the picture? are they snakes? if they are, then they must be snakes who have all one head; for see, they are joined together at their larger ends; and snakes which are branched, too, which no snake ever was. yes. i suppose they are not snakes. and they grow out of a flower, too; and it has a stalk, jointed, too, as plants sometimes are; and as fishes' backbones are too. is it a petrified plant or flower? no; though i do not deny that it looks like one. the creature most akin to it which you ever saw is a star-fish. what! one of the red star-fishes which one finds on the beach? its arms are not branched. no. but there are star-fishes with branched arms still in the sea. you know that pretty book (and learned book, too), forbes's _british star- fishes_? you like to look it through for the sake of the vignettes,--the mermaid and her child playing in the sea. oh yes, and the kind bogie who is piping while the sandstars dance; and the other who is trying to pull out the star-fish which the oyster has caught. yes. but do you recollect the drawing of the medusa's head, with its curling arms, branched again and again without end? here it is. no, you shall not look at the vignettes now. we must mind business. now look at this one; the feather-star, with arms almost like fern-fronds. and in foreign seas there are many other branched star-fish beside. but they have no stalks? do not be too sure of that. this very feather-star, soon after it is born, grows a tiny stalk, by which it holds on to corallines and sea-weeds; and it is not till afterwards that it breaks loose from that stalk, and swims away freely into the wide water. and in foreign seas there are several star-fish still who grow on stalks all their lives, as this fossil one did. how strange that a live animal should grow on a stalk, like a flower! not quite like a flower. a flower has roots, by which it feeds in the soil. these things grow more like sea-weeds, which have no roots, but only hold on to the rock by the foot of the stalk, as a ship holds on by her anchor. but as for its being strange that live animals should grow on stalks, if it be strange it is common enough, like many far stranger things. for under the water are millions on millions of creatures, spreading for miles on miles, building up at last great reefs of rocks, and whole islands, which all grow rooted first to the rock, like sea-weeds; and what is more, they grow, most of them, from one common root, branching again and again, and every branchlet bearing hundreds of living creatures, so that the whole creation is at once one creature and many creatures. do you not understand me? no. then fancy to yourself a bush like that hawthorn bush, with numberless blossoms, and every blossom on that bush a separate living thing, with its own mouth, and arms, and stomach, budding and growing fresh live branches and fresh live flowers, as fast as the old ones die: and then you will see better what i mean. how wonderful! yes; but not more wonderful than your finger, for it, too, is made up of numberless living things. my finger made of living things? what else can it be? when you cut your finger, does not the place heal? of course. and what is healing but growing again? and how could the atoms of your fingers grow, and make fresh skin, if they were not each of them alive? there, i will not puzzle you with too much at once; you will know more about all that some day. only remember now, that there is nothing wonderful in the world outside you but has its counterpart of something just as wonderful, and perhaps more wonderful, inside you. man is the microcosm, the little world, said the philosophers of old; and philosophers nowadays are beginning to see that their old guess is actual fact and true. but what are these curious sea-creatures called, which are animals, yet grow like plants? they have more names than i can tell you, or you remember. those which helped to make this bit of stone are called coral-insects: but they are not really insects, and are no more like insects than you are. coral-polypes is the best name for them, because they have arms round their mouths, something like a cuttlefish, which the ancients called polypus. but the animal which you have seen likest to most of them is a sea-anemone. look now at this piece of fresh coral--for coral it is, though not like the coral which your sister wears in her necklace. you see it is full of pipes; in each of those pipes has lived what we will call, for the time being, a tiny sea-anemone, joined on to his brothers by some sort of flesh and skin; and all of them together have built up, out of the lime in the sea-water, this common house, or rather town, of lime. but is it not strange and wonderful? of course it is: but so is everything when you begin to look into it; and if i were to go on, and tell you what sort of young ones these coral-polypes have, and what becomes of them, you would hear such wonders, that you would be ready to suspect that i was inventing nonsense, or talking in my dreams. but all that belongs to madam how's deepest book of all, which is called the book of kind: the book which children cannot understand, and in which only the very wisest men are able to spell out a few words, not knowing, and of course not daring to guess, what wonder may come next. now we will go back to our stone, and talk about how it was made, and how the stalked star-fish, which you mistook for a flower, ever got into the stone. then do you think me silly for fancying that a fossil star-fish was a flower? i should be silly if i did. there is no silliness in not knowing what you cannot know. you can only guess about new things, which you have never seen before, by comparing them with old things, which you have seen before; and you had seen flowers, and snakes, and fishes' backbones, and made a very fair guess from them. after all, some of these stalked star- fish are so like flowers, lilies especially, that they are called encrinites; and the whole family is called crinoids, or lily-like creatures, from the greek work _krinon_, a lily; and as for corals and corallines, learned men, in spite of all their care and shrewdness, made mistake after mistake about them, which they had to correct again and again, till now, i trust, they have got at something very like the truth. no, i shall only call you silly if you do what some little boys are apt to do--call other boys, and, still worse, servants or poor people, silly for not knowing what they cannot know. but are not poor people often very silly about animals and plants? the boys at the village school say that slowworms are poisonous; is not that silly? not at all. they know that adders bite, and so they think that slowworms bite too. they are wrong; and they must be told that they are wrong, and scolded if they kill a slowworm. but silly they are not. but is it not silly to fancy that swallows sleep all the winter at the bottom of the pond? i do not think so. the boys cannot know where the swallows go; and if you told them--what is true--that the swallows find their way every autumn through france, through spain, over the straits of gibraltar, into morocco, and some, i believe, over the great desert of zahara into negroland: and if you told them--what is true also--that the young swallows actually find their way into africa without having been along the road before; because the old swallows go south a week or two first, and leave the young ones to guess out the way for themselves: if you told them that, then they would have a right to say, "do you expect us to believe that? that is much more wonderful than that the swallows should sleep in the pond." but is it? yes; to them. they know that bats and dormice and other things sleep all the winter; so why should not swallows sleep? they see the swallows about the water, and often dipping almost into it. they know that fishes live under water, and that many insects--like may-flies and caddis-flies and water-beetles--live sometimes in the water, sometimes in the open air; and they cannot know--you do not know--what it is which prevents a bird's living under water. so their guess is really a very fair one; no more silly than that of the savages, who when they first saw the white men's ships, with their huge sails, fancied they were enormous sea-birds; and when they heard the cannons fire, said that the ships spoke in thunder and lightning. their guess was wrong, but not silly; for it was the best guess they could make. but i do know of one old woman who was silly. she was a boy's nurse, and she gave the boy a thing which she said was one of the snakes which st. hilda turned into stone; and told him that they found plenty of them at whitby, where she was born, all coiled up; but what was very odd, their heads had always been broken of. and when he took it, to his father, he told him it was only a fossil shell--an ammonite. and he went back and laughed at his nurse, and teased her till she was quite angry. then he was very lucky that she did not box his ears, for that was what he deserved. i dare say that, though his nurse had never heard of ammonites, she was a wise old dame enough, and knew a hundred things which he did not know, and which were far more important than ammonites, even to him. how? because if she had not known how to nurse him well, he would perhaps have never grown up alive and strong. and if she had not known how to make him obey and speak the truth, he might have grown up a naughty boy. but was she not silly? no. she only believed what the whitby folk, i understand, have some of them believed for many hundred years. and no one can be blamed for thinking as his forefathers did, unless he has cause to know better. surely she might have known better? how? what reason could she have to believe the ammonite was a shell? it is not the least like cockles, or whelks, or any shell she ever saw. what reason either could she have to guess that whitby cliff had once been coral-mud, at the bottom of the sea? no more reason, my dear child, than you would have to guess that this stone had been coral-mud likewise, if i did not teach you so,--or rather, try to make you teach yourself so. no. i say it again. if you wish to learn, i will only teach you on condition that you do not laugh at, or despise, those good and honest and able people who do not know or care about these things, because they have other things to think of: like old john out there ploughing. he would not believe you--he would hardly believe me--if we told him that this stone had been once a swarm of living things, of exquisite shapes and glorious colours. and yet he can plough and sow, and reap and mow, and fell and strip, and hedge and ditch, and give his neighbours sound advice, and take the measure of a man's worth from ten minutes' talk, and say his prayers, and keep his temper, and pay his debts,--which last three things are more than a good many folks can do who fancy themselves a whole world wiser than john in the smock-frock. oh, but i want to hear about the exquisite shapes and glorious colours. of course you do, little man. a few fine epithets take your fancy far more than a little common sense and common humility; but in that you are no worse than some of your elders. so now for the exquisite shapes and glorious colours. i have never seen them; though i trust to see them ere i die. so what they are like i can only tell from what i have learnt from mr. darwin, and mr. wallace, and mr. jukes, and mr. gosse, and last, but not least, from one whose soul was as beautiful as his face, lucas barrett,--too soon lost to science,--who was drowned in exploring such a coral-reef as this stone was once. then there are such things alive now? yes, and no. the descendants of most of them live on, altered by time, which alters all things; and from the beauty of the children we can guess at the beauty of their ancestors; just as from the coral-reefs which exist now we can guess how the coral-reefs of old were made. and that this stone was once part of a coral-reef the corals in it prove at first sight. and what is a coral-reef like? you have seen the room in the british museum full of corals, madrepores, brain-stones, corallines, and sea-ferns? oh yes. then fancy all those alive. not as they are now, white stone: but covered in jelly; and out of every pore a little polype, like a flower, peeping out. fancy them of every gaudy colour you choose. no bed of flowers, they say, can be more brilliant than the corals, as you look down on them through the clear sea. fancy, again, growing among them and crawling over them, strange sea-anemones, shells, star-fish, sea-slugs, and sea-cucumbers with feathery gills, crabs, and shrimps, and hundreds of other animals, all as strange in shape, and as brilliant in colour. you may let your fancy run wild. nothing so odd, nothing so gay, even entered your dreams, or a poet's, as you may find alive at the bottom of the sea, in the live flower-gardens of the sea-fairies. there will be shoals of fish, too, playing in and out, as strange and gaudy as the rest,--parrot-fish who browse on the live coral with their beak-like teeth, as cattle browse on grass; and at the bottom, it may be, larger and uglier fish, who eat the crabs and shell-fish, shells and all, grinding them up as a dog grinds a bone, and so turning shells and corals into fine soft mud, such as this stone is partly made of. but what happens to all the delicate little corals if a storm comes on? what, indeed? madam how has made them so well and wisely, that, like brave and good men, the more trouble they suffer the stronger they are. day and night, week after week, the trade-wind blows upon them, hurling the waves against them in furious surf, knocking off great lumps of coral, grinding them to powder, throwing them over the reef into the shallow water inside. but the heavier the surf beats upon them, the stronger the polypes outside grow, repairing their broken houses, and building up fresh coral on the dead coral below, because it is in the fresh sea-water that beats upon the surf that they find most lime with which to build. and as they build they form a barrier against the surf, inside of which, in water still as glass, the weaker and more delicate things can grow in safety, just as these very encrinites may have grown, rooted in the lime-mud, and waving their slender arms at the bottom of the clear lagoon. such mighty builders are these little coral polypes, that all the works of men are small compared with theirs. one single reef, for instance, which is entirely made by them, stretches along the north-east coast of australia for nearly a thousand miles. of this you must read some day in mr. jukes's _voyage of h.m.s. "fly_." every island throughout a great part of the pacific is fringed round each with its coral-reef, and there are hundreds of islands of strange shapes, and of atolls, as they are called, or ring-islands, which are composed entirely of coral, and of nothing else. a ring-island? how can an island be made in the shape of a ring? ah! it was a long time before men found out that riddle. mr. darwin was the first to guess the answer, as he has guessed many an answer beside. these islands are each a ring, or nearly a ring of coral, with smooth shallow water inside: but their outsides run down, like a mountain wall, sheer into seas hundreds of fathoms deep. people used to believe, and reasonably enough, that the coral polypes began to build up the islands from the very bottom of the deep sea. but that would not account for the top of them being of the shape of a ring; and in time it was found out that the corals would not build except in shallow water, twenty or thirty fathoms deep at most, and men were at their wits' ends to find out the riddle. then said mr. darwin, "suppose one of those beautiful south sea islands, like tahiti, the queen of isles, with its ring of coral-reef all round its shore, began sinking slowly under the sea. the land, as it sunk, would be gone for good and all: but the coral-reef round it would not, because the coral polypes would build up and up continually upon the skeletons of their dead parents, to get to the surface of the water, and would keep close to the top outside, however much the land sunk inside; and when the island had sunk completely beneath the sea, what would be left? what must be left but a ring of coral reef, around the spot where the last mountain peak of the island sank beneath the sea?" and so mr. darwin explained the shapes of hundreds of coral islands in the pacific; and proved, too, some strange things besides (he proved, and other men, like mr. wallace, whose excellent book on the east indian islands you must read some day, have proved in other ways) that there was once a great continent, joined perhaps to australia and to new guinea, in the pacific ocean, where is now nothing but deep sea, and coral-reefs which mark the mountain ranges of that sunken world. but how does the coral ever rise above the surface of the water and turn into hard stone? of course the coral polypes cannot build above the high-tide mark; but the surf which beats upon them piles up their broken fragments just as a sea-beach is piled up, and hammers them together with that water hammer which is heavier and stronger than any you have ever seen in a smith's forge. and then, as is the fashion of lime, the whole mass sets and becomes hard, as you may see mortar set; and so you have a low island a few feet above the sea. then sea-birds come to it, and rest and build; and seeds are floated thither from far lands; and among them almost always the cocoa-nut, which loves to grow by the sea-shore, and groves of cocoa palms grow up upon the lonely isle. then, perhaps, trees and bushes are drifted thither before the trade-wind; and entangled in their roots are seeds of other plants, and eggs or cocoons of insects; and so a few flowers and a few butterflies and beetles set up for themselves upon the new land. and then a bird or two, caught in a storm and blown away to sea finds shelter in the cocoa-grove; and so a little new world is set up, in which (you must remember always) there are no four-footed beasts, nor snakes, nor lizards, nor frogs, nor any animals that cannot cross the sea. and on some of those islands they may live (indeed there is reason to believe they have lived), so long, that some of them have changed their forms, according to the laws of madam how, who sooner or later fits each thing exactly for the place in which it is meant to live, till upon some of them you may find such strange and unique creatures as the famous cocoa-nut crab, which learned men call _birgus latro_. a great crab he is, who walks upon the tips of his toes a foot high above the ground. and because he has often nothing to eat but cocoa-nuts, or at least they are the best things he can find, cocoa-nuts he has learned to eat, and after a fashion which it would puzzle you to imitate. some say that he climbs up the stems of the cocoa-nut trees, and pulls the fruit down for himself; but that, it seems, he does not usually do. what he does is this: when he finds a fallen cocoa-nut, he begins tearing away the thick husk and fibre with his strong claws; and he knows perfectly well which end to tear it from, namely, from the end where the three eye-holes are, which you call the monkey's face, out of one of which you know, the young cocoa-nut tree would burst forth. and when he has got to the eye-holes, he hammers through one of them with the point of his heavy claw. so far, so good: but how is he to get the meat out? he cannot put his claw in. he has no proboscis like a butterfly to insert and suck with. he is as far off from his dinner as the fox was when the stork offered him a feast in a long-necked jar. what then do you think he does? he turns himself round, puts in a pair of his hind pincers, which are very slender, and with them scoops the meat out of the cocoa-nut, and so puts his dinner into his mouth with his hind feet. and even the cocoa-nut husk he does not waste; for he lives in deep burrows which he makes like a rabbit; and being a luxurious crab, and liking to sleep soft in spite of his hard shell, he lines them with a quantity of cocoa-nut fibre, picked out clean and fine, just as if he was going to make cocoa-nut matting of it. and being also a clean crab, as i hope you are a clean little boy, he goes down to the sea every night to have his bath and moisten his gills, and so lives happy all his days, and gets so fat in his old age that he carries about his body nearly a quart of pure oil. that is the history of the cocoa-nut crab. and if any one tells me that that crab acts only on what is called "instinct"; and does not think and reason, just as you and i think and reason, though of course not in words as you and i do: then i shall be inclined to say that that person does not think nor reason either. then were there many coral-reefs in britain in old times? yes, many and many, again and again; some whole ages older than this, a bit of which you see, and some again whole ages newer. but look: then judge for yourself. look at this geological map. wherever you see a bit of blue, which is the mark for limestone, you may say, "there is a bit of old coral-reef rising up to the surface." but because i will not puzzle your little head with too many things at once, you shall look at one set of coral-reefs which are far newer than this bit of dudley limestone, and which are the largest, i suppose, that ever were in this country; or, at least, there is more of them left than of any others. look first at ireland. you see that almost all the middle of ireland is coloured blue. it is one great sheet of old coral-reef and coral-mud, which is now called the carboniferous limestone. you see red and purple patches rising out of it, like islands--and islands i suppose they were, of hard and ancient rock, standing up in the middle of the coral sea. but look again, and you will see that along the west coast of ireland, except in a very few places, like galway bay, the blue limestone does not come down to the sea; the shore is coloured purple and brown, and those colours mark the ancient rocks and high mountains of mayo and galway and kerry, which stand as barriers to keep the raging surf of the atlantic from bursting inland and beating away, as it surely would in course of time, the low flat limestone plain of the middle of ireland. but the same coral-reefs once stretched out far to the westward into the atlantic ocean; and you may see the proof upon that map. for in the western bays, in clew bay with its hundred islands, and galway bay with its isles of arran, and beautiful kenmare, and beautiful bantry, you see little blue spots, which are low limestone islands, standing in the sea, overhung by mountains far aloft. you have often heard those islands in kenmare bay talked of, and how some whom you know go to fish round them by night for turbot and conger; and when you hear them spoken of again, you must recollect that they are the last fragments of a great fringing coral-reef, which will in a few thousand years follow the fate of the rest, and be eaten up by the waves, while the mountains of hard rock stand round them still unchanged. now look at england, and there you will see patches at least of a great coral-reef which was forming at the same time as that irish one, and on which perhaps some of your schoolfellows have often stood. you have heard of st. vincent's rocks at bristol, and the marble cliffs, feet in height, covered in part with rich wood and rare flowers, and the avon running through the narrow gorge, and the stately ships sailing far below your feet from bristol to the severn sea. and you may see, for here they are, corals from st. vincent's rocks, cut and polished, showing too that they also, like the dudley limestone, are made up of corals and of coral- mud. now, whenever you see st. vincent's rocks, as i suspect you very soon will, recollect where you are, and use your fancy, to paint for yourself a picture as strange as it is true. fancy that those rocks are what they once were, a coral-reef close to the surface of a shallow sea. fancy that there is no gorge of the avon, no wide severn sea--for those were eaten out by water ages and ages afterwards. but picture to yourself the coral sea reaching away to the north, to the foot of the welsh mountains; and then fancy yourself, if you will, in a canoe, paddling up through the coral-reefs, north and still north, up the valley down which the severn now flows, up through what is now worcestershire, then up through staffordshire, then through derbyshire, into yorkshire, and so on through durham and northumberland, till your find yourself stopped by the ettrick hills in scotland; while all to the westward of you, where is now the greater part of england, was open sea. you may say, if you know anything of the geography of england, "impossible! that would be to paddle over the tops of high mountains; over the top of the peak in derbyshire, over the top of high craven and whernside and pen-y- gent and cross fell, and to paddle too over the cheviot hills, which part england and scotland." i know it, my child, i know it. but so it was once on a time. the high limestone mountains which part lancashire and yorkshire--the very chine and backbone of england--were once coral-reefs at the bottom of the sea. they are all made up of the carboniferous limestone, so called, as your little knowledge of latin ought to tell you, because it carries the coal; because the coalfields usually lie upon it. it may be impossible in your eyes: but remember always that nothing is impossible with god. but you said that the coal was made from plants and trees, and did plants and trees grow on this coral-reef? that i cannot say. trees may have grown on the dry parts of the reef, as cocoa-nuts grow now in the pacific. but the coal was not laid down upon it till long afterwards, when it had gone through many and strange changes. for all through the chine of england, and in a part of ireland too, there lies upon the top of the limestone a hard gritty rock, in some places three thousand feet thick, which is commonly called "the mill-stone grit." and above that again the coal begins. now to make that feet of hard rock, what must have happened? the sea-bottom must have sunk, slowly no doubt, carrying the coral-reefs down with it, feet at least. and meanwhile sand and mud, made from the wearing away of the old lands in the north must have settled down upon it. i say from the north--for there are no fossils, as far as i know, or sign of life, in these rocks of mill-stone grit; and therefore it is reasonable to suppose that they were brought from a cold current at the pole, too cold to allow sea-beasts to live,--quite cold enough, certainly, to kill coral insects, who could only thrive in warm water coming from the south. then, to go on with my story, upon the top of these mill-stone grits came sand and mud, and peat, and trees, and plants, washed out to sea, as far as we can guess, from the mouths of vast rivers flowing from the west, rivers as vast as the amazon, the mississippi, or the orinoco are now; and so in long ages, upon the top of the limestone and upon the top of the mill-stone grit, were laid down those beds of coal which you see burnt now in every fire. but how did the coral-reefs rise till they became cliffs at bristol and mountains in yorkshire? the earthquake steam, i suppose, raised them. one earthquake indeed, or series of earthquakes, there was, running along between lancashire and yorkshire, which made that vast crack and upheaval in the rocks, the craven fault, running, i believe, for more than a hundred miles, and lifting the rocks in some places several hundred feet. that earthquake helped to make the high hills which overhang manchester and preston, and all the manufacturing county of lancashire. that earthquake helped to make the perpendicular cliff at malham cove, and many another beautiful bit of scenery. and that and other earthquakes, by heating the rocks from the fires below, may have helped to change them from soft coral into hard crystalline marble as you see them now, just as volcanic heat has hardened and purified the beautiful white marbles of pentelicus and paros in greece, and carrara in italy, from which statues are carved unto this day. or the same earthquake may have heated and hardened the limestones simply by grinding and squeezing them; or they may have been heated and hardened in the course of long ages simply by the weight of the thousands of feet of other rock which lay upon them. for pressure, you must remember, produces heat. when you strike flint and steel together, the pressure of the blow not only makes bits of steel fly off, but makes them fly off in red-hot sparks. when you hammer a piece of iron with a hammer, you will soon find it get quite warm. when you squeeze the air together in your pop-gun, you actually make the air inside warmer, till the pellet flies out, and the air expands and cools again. nay, i believe you cannot hold up a stone on the palm of your hand without that stone after a while warming your hand, because it presses against you in trying to fall, and you press against it in trying to hold it up. and recollect above all the great and beautiful example of that law which you were lucky enough to see on the night of the th of november , how those falling stars, as i told you then, were coming out of boundless space, colder than any ice on earth, and yet, simply by pressing against the air above our heads, they had their motion turned into heat, till they burned themselves up into trains of fiery dust. so remember that wherever you have pressure you have heat, and that the pressure of the upper rocks upon the lower is quite enough, some think, to account for the older and lower rocks being harder than the upper and newer ones. but why should the lower rocks be older and the upper rocks newer? you told me just now that the high mountains in wales were ages older than windsor forest, upon which we stand: but yet how much lower we are here than if we were on a welsh mountain. ah, my dear child, of course that puzzles you, and i am afraid it must puzzle you still till we have another talk; or rather it seems to me that the best way to explain that puzzle to you would be for you and me to go a journey into the far west, and look into the matter for ourselves; and from here to the far west we will go, either in fancy or on a real railroad and steamboat, before we have another talk about these things. now it is time to stop. is there anything more you want to know? for you look as if something was puzzling you still. were there any men in the world while all this was going on? i think not. we have no proof that there were not: but also we have no proof that there were; the cave-men, of whom i told you, lived many ages after the coal was covered up. you seem to be sorry that there were no men in the world then. because it seems a pity that there was no one to see those beautiful coral-reefs and coal-forests. no one to see them, my child? who told you that? who told you there are not, and never have been any rational beings in this vast universe, save certain weak, ignorant, short-sighted creatures shaped like you and me? but even if it were so, and no created eye had ever beheld those ancient wonders, and no created heart ever enjoyed them, is there not one uncreated who has seen them and enjoyed them from the beginning? were not these creatures enjoying themselves each after their kind? and was there not a father in heaven who was enjoying their enjoyment, and enjoying too their beauty, which he had formed according to the ideas of his eternal mind? recollect what you were told on trinity sunday--that this world was not made for man alone: but that man, and this world, and the whole universe was made for god; for he created all things, and for his pleasure they are, and were created. chapter x--field and wild where were we to go next? into the far west, to see how all the way along the railroads the new rocks and soils lie above the older, and yet how, when we get westward, the oldest rocks rise highest into the air. well, we will go: but not, i think, to-day. indeed i hardly know how we could get as far as reading; for all the world is in the hay-field, and even the old horse must go thither too, and take his turn at the hay-cart. well, the rocks have been where they are for many a year, and they will wait our leisure patiently enough: but midsummer and the hay- field will not wait. let us take what god gives when he sends it, and learn the lesson that lies nearest to us. after all, it is more to my old mind, and perhaps to your young mind too, to look at things which are young and fresh and living, rather than things which are old and worn and dead. let us leave the old stones, and the old bones, and the old shells, the wrecks of ancient worlds which have gone down into the kingdom of death, to teach us their grand lessons some other day; and let us look now at the world of light and life and beauty, which begins here at the open door, and stretches away over the hay-fields, over the woods, over the southern moors, over sunny france, and sunnier spain, and over the tropic seas, down to the equator, and the palm-groves of the eternal summer. if we cannot find something, even at starting from the open door, to teach us about why and how, we must be very short-sighted, or very shallow-hearted. there is the old cock starling screeching in the eaves, because he wants to frighten us away, and take a worm to his children, without our finding out whereabouts his hole is. how does he know that we might hurt him? and how again does he not know that we shall not hurt him? we, who for five-and-twenty years have let him and his ancestors build under those eaves in peace? how did he get that quantity of half-wit, that sort of stupid cunning, into his little brain, and yet get no more? and why (for this is a question of why, and not of how) does he labour all day long, hunting for worms and insects for his children, while his wife nurses them in the nest? why, too, did he help her to build that nest with toil and care this spring, for the sake of a set of nestlings who can be of no gain or use to him, but only take the food out of his mouth? simply out of--what shall i call it, my child?--love; that same sense of love and duty, coming surely from that one fountain of all duty and all love, which makes your father work for you. that the mother should take care of her young, is wonderful enough; but that (at least among many birds) the father should help likewise, is (as you will find out as you grow older) more wonderful far. so there already the old starling has set us two fresh puzzles about how and why, neither of which we shall get answered, at least on this side of the grave. come on, up the field, under the great generous sun, who quarrels with no one, grudges no one, but shines alike upon the evil and the good. what a gay picture he is painting now, with his light-pencils; for in them, remember, and not in the things themselves the colour lies. see how, where the hay has been already carried, he floods all the slopes with yellow light, making them stand out sharp against the black shadows of the wood; while where the grass is standing still, he makes the sheets of sorrel-flower blush rosy red, or dapples the field with white oxeyes. but is not the sorrel itself red, and the oxeyes white? what colour are they at night, when the sun is gone? dark. that is, no colour. the very grass is not green at night. oh, but it is if you look at it with a lantern. no, no. it is the light of the lantern, which happens to be strong enough to make the leaves look green, though it is not strong enough to make a geranium look red. not red? no; the geranium flowers by a lantern look black, while the leaves look green. if you don't believe me, we will try. but why is that? why, i cannot tell: and how, you had best ask professor tyndall, if you ever have the honour of meeting him. but now--hark to the mowing-machine, humming like a giant night-jar. come up and look at it, and see how swift and smooth it shears the long grass down, so that in the middle of the swathe it seems to have merely fallen flat, and you must move it before you find that it has been cut off. ah, there is a proof to us of what men may do if they will only learn the lessons which madam how can teach them. there is that boy, fresh from the national school, cutting more grass in a day than six strong mowers could have cut, and cutting it better, too; for the mowing-machine goes so much nearer to the ground than the scythe, that we gain by it two hundredweight of hay on every acre. and see, too, how persevering old madam how will not stop her work, though the machine has cut off all the grass which she has been making for the last three months; for as fast as we shear it off, she makes it grow again. there are fresh blades, here at our feet, a full inch long, which have sprung up in the last two days, for the cattle when they are turned in next week. but if the machine cuts all the grass, the poor mowers will have nothing to do. not so. they are all busy enough elsewhere. there is plenty of other work to be done, thank god; and wholesomer and easier work than mowing with a burning sun on their backs, drinking gallons of beer, and getting first hot and then cold across the loins, till they lay in a store of lumbago and sciatica, to cripple them in their old age. you delight in machinery because it is curious: you should delight in it besides because it does good, and nothing but good, where it is used, according to the laws of lady why, with care, moderation, and mercy, and fair-play between man and man. for example: just as the mowing-machine saves the mowers, the threshing-machine saves the threshers from rheumatism and chest complaints,--which they used to catch in the draught and dust of the unhealthiest place in the whole parish, which is, the old-fashioned barn's floor. and so, we may hope, in future years all heavy drudgery and dirty work will be done more and more by machines, and people will have more and more chance of keeping themselves clean and healthy, and more and more time to read, and learn, and think, and be true civilised men and women, instead of being mere live ploughs, or live manure-carts, such as i have seen ere now. a live manure-cart? yes, child. if you had seen, as i have seen, in foreign lands, poor women, haggard, dirty, grown old before their youth was over, toiling up hill with baskets of foul manure upon their backs, you would have said, as i have said, "oh for madam how to cure that ignorance! oh for lady why to cure that barbarism! oh that madam how would teach them that machinery must always be cheaper in the long run than human muscles and nerves! oh that lady why would teach them that a woman is the most precious thing on earth, and that if she be turned into a beast of burden, lady why--and madam how likewise--will surely avenge the wrongs of their human sister!" there, you do not quite know what i mean, and i do not care that you should. it is good for little folk that big folk should now and then "talk over their heads," as the saying is, and make them feel how ignorant they are, and how many solemn and earnest questions there are in the world on which they must make up their minds some day, though not yet. but now we will talk about the hay: or rather do you and the rest go and play in the hay and gather it up, build forts of it, storm them, pull them down, build them up again, shout, laugh, and scream till you are hot and tired. you will please madam how thereby, and lady why likewise. how? because madam how naturally wants her work to succeed, and she is at work now making you. making me? of course. making a man of you, out of a boy. and that can only be done by the life-blood which runs through and through you. and the more you laugh and shout, the more pure air will pass into your blood, and make it red and healthy; and the more you romp and play--unless you overtire yourself--the quicker will that blood flow through all your limbs, to make bone and muscle, and help you to grow into a man. but why does lady why like to see us play? she likes to see you happy, as she likes to see the trees and birds happy. for she knows well that there is no food, nor medicine either, like happiness. if people are not happy enough, they are often tempted to do many wrong deeds, and to think many wrong thoughts: and if by god's grace they know the laws of lady why, and keep from sin, still unhappiness, if it goes on too long, wears them out, body and mind; and they grow ill and die, of broken hearts, and broken brains, my child; and so at last, poor souls, find "rest beneath the cross." children, too, who are unhappy; children who are bullied, and frightened, and kept dull and silent, never thrive. their bodies do not thrive; for they grow up weak. their minds do not thrive; for they grow up dull. their souls do not thrive; for they learn mean, sly, slavish ways, which god forbid you should ever learn. well said the wise man, "the human plant, like the vegetables, can only flower in sunshine." so do you go, and enjoy yourself in the sunshine; but remember this--you know what happiness is. then if you wish to please lady why, and lady why's lord and king likewise, you will never pass a little child without trying to make it happier, even by a passing smile. and now be off, and play in the hay, and come back to me when you are tired. * * * * * let us lie down at the foot of this old oak, and see what we can see. and hear what we can hear, too. what is that humming all round us, now that the noisy mowing-machine has stopped? and as much softer than the noise of mowing-machine hum, as the machines which make it are more delicate and more curious. madam how is a very skilful workwoman, and has eyes which see deeper and clearer than all microscopes; as you would find, if you tried to see what makes that "midsummer hum" of which the haymakers are so fond, because it promises fair weather. why, it is only the gnats and flies. only the gnats and flies? you might study those gnats and flies for your whole life without finding out all--or more than a very little--about them. i wish i knew how they move those tiny wings of theirs--a thousand times in a second, i dare say, some of them. i wish i knew how far they know that they are happy--for happy they must be, whether they know it or not. i wish i knew how they live at all. i wish i even knew how many sorts there are humming round us at this moment. how many kinds? three or four? more probably thirty or forty round this single tree. but why should there be so many kinds of living things? would not one or two have done just as well? why, indeed? why should there not have been only one sort of butterfly, and he only of one colour, a plain brown, or a plain white? and why should there be so many sorts of birds, all robbing the garden at once? thrushes, and blackbirds, and sparrows, and chaffinches, and greenfinches, and bullfinches, and tomtits. and there are four kinds of tomtits round here, remember: but we may go on with such talk for ever. wiser men than we have asked the same question: but lady why will not answer them yet. however, there is another question, which madam how seems inclined to answer just now, which is almost as deep and mysterious. what? _how_ all these different kinds of things became different. oh, do tell me! not i. you must begin at the beginning, before you can end at the end, or even make one step towards the end. what do you mean? you must learn the differences between things, before you can find out how those differences came about. you must learn madam how's alphabet before you can read her book. and madam how's alphabet of animals and plants is, species, kinds of things. you must see which are like, and which unlike; what they are like in, and what they are unlike in. you are beginning to do that with your collection of butterflies. you like to arrange them, and those that are most like nearest to each other, and to compare them. you must do that with thousands of different kinds of things before you can read one page of madam how's natural history book rightly. but it will take so much time and so much trouble. god grant that you may not spend more time on worse matters, and take more trouble over things which will profit you far less. but so it must be, willy-nilly. you must learn the alphabet if you mean to read. and you must learn the value of the figures before you can do a sum. why, what would you think of any one who sat down to play at cards--for money too (which i hope and trust you never will do)--before he knew the names of the cards, and which counted highest, and took the other? of course he would be very foolish. just as foolish are those who make up "theories" (as they call them) about this world, and how it was made, before they have found out what the world is made of. you might as well try to find out how this hay- field was made, without finding out first what the hay is made of. how the hay-field was made? was it not always a hay-field? ah, yes; the old story, my child: was not the earth always just what it is now? let us see for ourselves whether this was always a hay-field. how? just pick out all the different kinds of plants and flowers you can find round us here. how many do you think there are? oh--there seem to be four or five. just as there were three or four kinds of flies in the air. pick them, child, and count. let us have facts. how many? what! a dozen already? yes--and here is another, and another. why, i have got i don't know how many. why not? bring them here, and let us see. nine kinds of grasses, and a rush. six kinds of clovers and vetches; and besides, dandelion, and rattle, and oxeye, and sorrel, and plantain, and buttercup, and a little stitchwort, and pignut, and mouse-ear hawkweed, too, which nobody wants. why? because they are a sign that i am not a good farmer enough, and have not quite turned my wild into field. what do you mean? look outside the boundary fence, at the moors and woods; they are forest, wild--"wald," as the germans would call it. inside the fence is field--"feld," as the germans would call it. guess why? is it because the trees inside have been felled? well, some say so, who know more than i. but now go over the fence, and see how many of these plants you can find on the moor. oh, i think i know. i am so often on the moor. i think you would find more kinds outside than you fancy. but what do you know? that beside some short fine grass about the cattle-paths, there are hardly any grasses on the moor save deer's hair and glade-grass; and all the rest is heath, and moss, and furze, and fern. softly--not all; you have forgotten the bog plants; and there are (as i said) many more plants beside on the moor than you fancy. but we will look into that another time. at all events, the plants outside are on the whole quite different from the hay-field. of course: that is what makes the field look green and the moor brown. not a doubt. they are so different, that they look like bits of two different continents. scrambling over the fence is like scrambling out of europe into australia. now, how was that difference made? think. don't guess, but think. why does the rich grass come up to the bank, and yet not spread beyond it? i suppose because it cannot get over. not get over? would not the wind blow the seeds, and the birds carry them? they do get over, in millions, i don't doubt, every summer. then why do they not grow? think. is there any difference in the soil inside and out? a very good guess. but guesses are no use without facts. look. oh, i remember now. i know now the soil of the field is brown, like the garden; and the soil of the moor all black and peaty. yes. but if you dig down two or three feet, you will find the soils of the moor and the field just the same. so perhaps the top soils were once both alike. i know. well, and what do you think about it now? i want you to look and think. i want every one to look and think. half the misery in the world comes first from not looking, and then from not thinking. and i do not want you to be miserable. but shall i be miserable if i do not find out such little things as this. you will be miserable if you do not learn to understand little things: because then you will not be able to understand great things when you meet them. children who are not trained to use their eyes and their common sense grow up the more miserable the cleverer they are. why? because they grow up what men call dreamers, and bigots, and fanatics, causing misery to themselves and to all who deal with them. so i say again, think. well, i suppose men must have altered the soil inside the bank. well done. but why do you think so? because, of course, some one made the bank; and the brown soil only goes up to it. well, that is something like common sense. now you will not say any more, as the cows or the butterflies might, that the hay-field was always there. and how did men change the soil? by tilling it with the plough, to sweeten it, and manuring it, to make it rich. and then did all these beautiful grasses grow up of themselves? you ought to know that they most likely did not. you know the new enclosures? yes. well then, do rich grasses come up on them, now that they are broken up? oh no, nothing but groundsel, and a few weeds. just what, i dare say, came up here at first. but this land was tilled for corn, for hundreds of years, i believe. and just about one hundred years ago it was laid down in grass; that is, sown with grass seeds. and where did men get the grass seeds from? ah, that is a long story; and one that shows our forefathers (though they knew nothing about railroads or electricity) were not such simpletons as some folks think. the way it must have been done was this. men watched the natural pastures where cattle get fat on the wild grass, as they do in the fens, and many other parts of england. and then they saved the seeds of those fattening wild grasses, and sowed them in fresh spots. often they made mistakes. they were careless, and got weeds among the seed--like the buttercups, which do so much harm to this pasture. or they sowed on soil which would not suit the seed, and it died. but at last, after many failures, they have grown so careful and so clever, that you may send to certain shops, saying what sort of soil yours is, and they will send you just the seeds which will grow there, and no other; and then you have a good pasture for as long as you choose to keep it good. and how is it kept good? look at all those loads of hay, which are being carried off the field. do you think you can take all that away without putting anything in its place? why not? if i took all the butter out of the churn, what must i do if i want more butter still? put more cream in. so, if i want more grass to grow, i must put on the soil more of what grass is made of. but the butter don't grow, and the grass does. what does the grass grow in? the soil. yes. just as the butter grows in the churn. so you must put fresh grass- stuff continually into the soil, as you put fresh cream into the churn. you have heard the farm men say, "that crop has taken a good deal out of the land"? yes. then they spoke exact truth. what will that hay turn into by christmas? can't you tell? into milk, of course, which you will drink; and into horseflesh too, which you will use. use horseflesh? not eat it? no; we have not got as far as that. we did not even make up our minds to taste the cambridge donkey. but every time the horse draws the carriage, he uses up so much muscle; and that muscle he must get back again by eating hay and corn; and that hay and corn must be put back again into the land by manure, or there will be all the less for the horse next year. for one cannot eat one's cake and keep it too; and no more can one eat one's grass. so this field is a truly wonderful place. it is no ugly pile of brick and mortar, with a tall chimney pouring out smoke and evil smells, with unhealthy, haggard people toiling inside. why do you look surprised? because--because nobody ever said it was. you mean a manufactory. well, and this hay-field is a manufactory: only like most of madam how's workshops, infinitely more beautiful, as well as infinitely more crafty, than any manufactory of man's building. it is beautiful to behold, and healthy to work in; a joy and blessing alike to the eye, and the mind, and the body: and yet it is a manufactory. but a manufactory of what? of milk of course, and cows, and sheep, and horses; and of your body and mine--for we shall drink the milk and eat the meat. and therefore it is a flesh and milk manufactory. we must put into it every year yard-stuff, tank-stuff, guano, bones, and anything and everything of that kin, that madam how may cook it for us into grass, and cook the grass again into milk and meat. but if we don't give madam how material to work on, we cannot expect her to work for us. and what do you think will happen then? she will set to work for herself. the rich grasses will dwindle for want of ammonia (that is smelling salts), and the rich clovers for want of phosphates (that is bone-earth): and in their places will come over the bank the old weeds and grass off the moor, which have not room to get in now, because the ground is coveted already. they want no ammonia nor phosphates--at all events they have none, and that is why the cattle on the moor never get fat. so they can live where these rich grasses cannot. and then they will conquer and thrive; and the field will turn into wild once more. ah, my child, thank god for your forefathers, when you look over that boundary mark. for the difference between the field and the wild is the difference between the old england of madam how's making, and the new england which she has taught man to make, carrying on what she had only begun and had not time to finish. that moor is a pattern bit left to show what the greater part of this land was like for long ages after it had risen out of the sea; when there was little or nothing on the flat upper moors save heaths, and ling, and club-mosses, and soft gorse, and needle-whin, and creeping willows; and furze and fern upon the brows; and in the bottoms oak and ash, beech and alder, hazel and mountain ash, holly and thorn, with here and there an aspen or a buckthorn (berry-bearing alder as you call it), and everywhere--where he could thrust down his long root, and thrust up his long shoots--that intruding conqueror and insolent tyrant, the bramble. there were sedges and rushes, too, in the bogs, and coarse grass on the forest pastures--or "leas" as we call them to this day round here--but no real green fields; and, i suspect, very few gay flowers, save in spring the sheets of golden gorse, and in summer the purple heather. such was old england--or rather, such was this land before it was england; a far sadder, damper, poorer land than now. for one man or one cow or sheep which could have lived on it then, a hundred can live now. and yet, what it was once, that it might become again,--it surely would round here, if this brave english people died out of it, and the land was left to itself once more. what would happen then, you may guess for yourself, from what you see happen whenever the land is left to itself, as it is in the wood above. in that wood you can still see the grass ridges and furrows which show that it was once ploughed and sown by man; perhaps as late as the time of henry the eighth, when a great deal of poor land, as you will read some day, was thrown out of tillage, to become forest and down once more. and what is the mount now? a jungle of oak and beech, cherry and holly, young and old all growing up together, with the mountain ash and bramble and furze coming up so fast beneath them, that we have to cut the paths clear again year by year. why, even the little cow-wheat, a very old- world plant, which only grows in ancient woods, has found its way back again, i know not whence, and covers the open spaces with its pretty yellow and white flowers. man had conquered this mount, you see, from madam how, hundreds of years ago. and she always lets man conquer her, because lady why wishes man to conquer: only he must have a fair fight with madam how first, and try his strength against hers to the utmost. so man conquered the wood for a while; and it became cornfield instead of forest: but he was not strong and wise enough three hundred years ago to keep what he had conquered; and back came madam how, and took the place into her own hands, and bade the old forest trees and plants come back again--as they would come if they were not stopped year by year, down from the wood, over the pastures--killing the rich grasses as they went, till they met another forest coming up from below, and fought it for many a year, till both made peace, and lived quietly side by side for ages. another forest coming up from below? where would it come from? from where it is now. come down and look along the brook, and every drain and grip which runs into the brook. what is here? seedling alders, and some withies among them. very well. you know how we pull these alders up, and cut them down, and yet they continually come again. now, if we and all human beings were to leave this pasture for a few hundred years, would not those alders increase into a wood? would they not kill the grass, and spread right and left, seeding themselves more and more as the grass died, and left the ground bare, till they met the oaks and beeches coming down the hill? and then would begin a great fight, for years and years, between oak and beech against alder and willow. but how can trees fight? could they move or beat each other with their boughs? not quite that; though they do beat each other with their boughs, fiercely enough, in a gale of wind; and then the trees who have strong and stiff boughs wound those who have brittle and limp boughs, and so hurt them, and if the storms come often enough, kill them. but among these trees in a sheltered valley the larger and stronger would kill the weaker and smaller by simply overshadowing their tops, and starving their roots; starving them, indeed, so much when they grow very thick, that the poor little acorns, and beech mast, and alder seeds would not be able to sprout at all. so they would fight, killing each other's children, till the war ended--i think i can guess how. how? the beeches are as dainty as they are beautiful; and they do not like to get their feet wet. so they would venture down the hill only as far as the dry ground lasts, and those who tried to grow any lower would die. but the oaks are hardy, and do not care much where they grow. so they would fight their way down into the wet ground among the alders and willows, till they came to where their enemies were so thick and tall, that the acorns as they fell could not sprout in the darkness. and so you would have at last, along the hill-side, a forest of beech and oak, lower down a forest of oak and alder, and along the stream-side alders and willows only. and that would be a very fair example of the great law of the struggle for existence, which causes the competition of species. what is that? madam how is very stern, though she is always perfectly just; and therefore she makes every living thing fight for its life, and earn its bread, from its birth till its death; and rewards it exactly according to its deserts, and neither more nor less. and the competition of species means, that each thing, and kind of things, has to compete against the things round it; and to see which is the stronger; and the stronger live, and breed, and spread, and the weaker die out. but that is very hard. i know it, my child, i know it. but so it is. and madam how, no doubt, would be often very clumsy and very cruel, without meaning it, because she never sees beyond her own nose, or thinks at all about the consequences of what she is doing. but lady why, who does think about consequences, is her mistress, and orders her about for ever. and lady why is, i believe, as loving as she is wise; and therefore we must trust that she guides this great war between living things, and takes care that madam how kills nothing which ought not to die, and takes nothing away without putting something more beautiful and something more useful in its place; and that even if england were, which god forbid, overrun once more with forests and bramble-brakes, that too would be of use somehow, somewhere, somewhen, in the long ages which are to come hereafter. and you must remember, too, that since men came into the world with rational heads on their shoulders, lady why has been handing over more and more of madam how's work to them, and some of her own work too: and bids them to put beautiful and useful things in the place of ugly and useless ones; so that now it is men's own fault if they do not use their wits, and do by all the world what they have done by these pastures--change it from a barren moor into a rich hay-field, by copying the laws of madam how, and making grass compete against heath. but you look thoughtful: what is it you want to know? why, you say all living things must fight and scramble for what they can get from each other: and must not i too? for i am a living thing. ah, that is the old question, which our lord answered long ago, and said, "be not anxious what ye shall eat or what ye shall drink, or wherewithal you shall be clothed. for after all these things do the heathen seek, and your heavenly father knoweth that ye have need of these things. but seek ye first the kingdom of god and his righteousness, and all these things shall be added to you." a few, very few, people have taken that advice. but they have been just the salt of the earth, which has kept mankind from decaying. but what has that to do with it? see. you are a living thing, you say. are you a plant? no. are you an animal? i do not know. yes. i suppose i am. i eat, and drink, and sleep, just as dogs and cats do. yes. there is no denying that. no one knew that better than st. paul when he told men that they had a flesh; that is, a body, and an animal's nature in them. but st. paul told them--of course he was not the first to say so, for all the wise heathens have known that--that there was something more in us, which he called a spirit. some call it now the moral sentiment, some one thing, some another, but we will keep to the old word: we shall not find a better. yes, i know that i have a spirit, a soul. better to say that you are a spirit. but what does st. paul say? that our spirit is to conquer our flesh, and keep it down. that the man in us, in short, which is made in the likeness of god, is to conquer the animal in us, which is made in the likeness of the dog and the cat, and sometimes (i fear) in the likeness of the ape or the pig. you would not wish to be like a cat, much less like an ape or a pig? of course not. then do not copy them, by competing and struggling for existence against other people. what do you mean? did you never watch the pigs feeding? yes, and how they grudge and quarrel, and shove each other's noses out of the trough, and even bite each other because they are so jealous which shall get most. that is it. and how the biggest pig drives the others away, and would starve them while he got fat, if the man did not drive him off in his turn. oh, yes; i know. then no wiser than those pigs are worldly men who compete, and grudge, and struggle with each other, which shall get most money, most fame, most power over their fellow-men. they will tell you, my child, that that is the true philosophy, and the true wisdom; that competition is the natural law of society, and the source of wealth and prosperity. do not you listen to them. that is the wisdom of this world, which the flesh teaches the animals; and those who follow it, like the animals, will perish. such men are not even as wise as sweep the retriever. not as wise as sweep? not they. sweep will not take away victor's bone, though he is ten times as big as victor, and could kill him in a moment; and when he catches a rabbit, does he eat it himself? of course not; he brings it and lays it down at our feet. because he likes better to do his duty, and be praised for it, than to eat the rabbit, dearly as he longs to eat it. but he is only an animal. who taught him to be generous, and dutiful, and faithful? who, indeed! not we, you know that, for he has grown up with us since a puppy. how he learnt it, and his parents before him, is a mystery, of which we can only say, god has taught them, we know not how. but see what has happened--that just because dogs have learnt not to be selfish and to compete--that is, have become civilised and tame--therefore we let them live with us, and love them. because they try to be good in their simple way, therefore they too have all things added to them, and live far happier, and more comfortable lives than the selfish wolf and fox. but why have not all animals found out that? i cannot tell: there may be wise animals and foolish animals, as there are wise and foolish men. indeed there are. i see a very wise animal there, who never competes; for she has learned something of the golden lesson--that it is more blessed to give than to receive; and she acts on what she has learnt, all day long. which do you mean? why, that is a bee. yes, it is a bee: and i wish i were as worthy in my place as that bee is in hers. i wish i could act up as well as she does to the true wisdom, which is self-sacrifice. for whom is that bee working? for herself? if that was all, she only needs to suck the honey as she goes. but she is storing up the wax under her stomach, and bee-bread in her thighs--for whom? not for herself only, or even for her own children: but for the children of another bee, her queen. for them she labours all day long, builds for them, feeds them, nurses them, spends her love and cunning on them. so does that ant on the path. she is carrying home that stick to build for other ants' children. so do the white ants in the tropics. they have learnt not to compete, but to help each other; not to be selfish, but to sacrifice themselves; and therefore they are strong. but you told me once that ants would fight and plunder each other's nests. and once we saw two hives of bees fighting in the air, and falling dead by dozens. my child, do not men fight, and kill each other by thousands with sharp shot and cold steel, because, though they have learnt the virtue of patriotism, they have not yet learnt that of humanity? we must not blame the bees and ants if they are no wiser than men. at least they are wise enough to stand up for their country, that is, their hive, and work for it, and die for it, if need be; and that makes them strong. but how does that make them strong? how, is a deep question, and one i can hardly answer yet. but that it has made them so there is no doubt. look at the solitary bees--the governors as we call them, who live in pairs, in little holes in the banks. how few of them there are; and they never seem to increase in numbers. then look at the hive bees, how, just because they are civilised,--that is, because they help each other, and feed each other, instead of being solitary and selfish,--they breed so fast, and get so much food, that if they were not killed for their honey, they would soon become a nuisance, and drive us out of the parish. but then we give them their hives ready made. true. but in old forest countries, where trees decay and grow hollow, the bees breed in them. yes. i remember the bee tree in the fir avenue. well then, in many forests in hot countries the bees swarm in hollow trees; and they, and the ants, and the white ants, have it all their own way, and are lords and masters, driving the very wild beasts before them, while the ants and white ants eat up all gardens, and plantations, and clothes, and furniture; till it is a serious question whether in some hot countries man will ever be able to settle, so strong have the ants grown, by ages of civilisation, and not competing against their brothers and sisters. but may i not compete for prizes against the other boys? well, there is no harm in that; for you do not harm the others, even if you win. they will have learnt all the more, while trying for the prize; and so will you, even if you don't get it. but i tell you fairly, trying for prizes is only fit for a child; and when you become a man, you must put away childish things--competition among the rest. but surely i may try to be better and wiser and more learned than everybody else? my dearest child, why try for that? try to be as good, and wise, and learned as you can, and if you find any man, or ten thousand men, superior to you, thank god for it. do you think that there can be too much wisdom in the world? of course not: but i should like to be the wisest man in it. then you would only have the heaviest burden of all men on your shoulders. why? because you would be responsible for more foolish people than any one else. remember what wise old moses said, when some one came and told him that certain men in the camp were prophesying--"would god all the lord's people did prophesy!" yes; it would have saved moses many a heartache, and many a sleepless night, if all the jews had been wise as he was, and wiser still. so do not you compete with good and wise men, but simply copy them: and whatever you do, do not compete with the wolves, and the apes, and the swine of this world; for that is a game at which you are sure to be beaten. why? because lady why, if she loves you (as i trust she does), will take care that you are beaten, lest you should fancy it was really profitable to live like a cunning sort of animal, and not like a true man. and how she will do that i can tell you. she will take care that you always come across a worse man than you are trying to be,--a more apish man, who can tumble and play monkey-tricks for people's amusement better than you can; or a more swinish man, who can get at more of the pig's-wash than you can; or a more wolfish man, who will eat you up if you do not get out of his way; and so she will disappoint and disgust you, my child, with that greedy, selfish, vain animal life, till you turn round and see your mistake, and try to live the true human life, which also is divine;--to be just and honourable, gentle and forgiving, generous and useful--in one word, to fear god, and keep his commandments: and as you live that life, you will find that, by the eternal laws of lady why, all other things will be added to you; that people will be glad to know you, glad to help you, glad to employ you, because they see that you will be of use to them, and will do them no harm. and if you meet (as you will meet) with people better and wiser than yourself, then so much the better for you; for they will love you, and be glad to teach you when they see that you are living the unselfish and harmless life; and that you come to them, not as foolish critias came to socrates, to learn political cunning, and become a selfish and ambitious tyrant, but as wise plato came, that he might learn the laws of lady why, and love them for her sake, and teach them to all mankind. and so you, like the plants and animals, will get your deserts exactly, without competing and struggling for existence as they do. and all this has come out of looking at the hay-field and the wild moor. why not? there is an animal in you, and there is a man in you. if the animal gets the upper hand, all your character will fall back into wild useless moor; if the man gets the upper hand, all your character will be cultivated into rich and fertile field. choose. now come down home. the haymakers are resting under the hedge. the horses are dawdling home to the farm. the sun is getting low, and the shadows long. come home, and go to bed while the house is fragrant with the smell of hay, and dream that you are still playing among the haycocks. when you grow old, you will have other and sadder dreams. chapter xi--the world's end hullo! hi! wake up. jump out of bed, and come to the window, and see where you are. what a wonderful place! so it is: though it is only poor old ireland. don't you recollect that when we started i told you we were going to ireland, and through it to the world's end; and here we are now safe at the end of the old world, and beyond us the great atlantic, and beyond that again, thousands of miles away, the new world, which will be rich and prosperous, civilised and noble, thousands of years hence, when this old world, it may be, will be dead, and little children there will be reading in their history books of ancient england and of ancient france, as you now read of greece and rome. but what a wonderful place it is! what are those great green things standing up in the sky, all over purple ribs and bars, with their tops hid in the clouds? those are mountains; the bones of some old world, whose poor bare sides madam how is trying to cover with rich green grass. and how far off are they? how i should like to walk up to the top of that one which looks quite close. you will find it a long walk up there; three miles, i dare say, over black bogs and banks of rock, and up corries and cliffs which you could not climb. there are plenty of cows on that mountain: and yet they look so small, you could not see them, nor i either, without a glass. that long white streak, zigzagging down the mountain side, is a roaring cataract of foam five hundred feet high, full now with last night's rain; but by this afternoon it will have dwindled to a little thread; and to- morrow, when you get up, if no more rain has come down, it will be gone. madam how works here among the mountains swiftly and hugely, and sometimes terribly enough; as you shall see when you have had your breakfast, and come down to the bridge with me. but what a beautiful place it is! flowers and woods and a lawn; and what is that great smooth patch in the lawn just under the window? is it an empty flower-bed? ah, thereby hangs a strange tale. we will go and look at it after breakfast, and then you shall see with your own eyes one of the wonders which i have been telling you of. and what is that shining between the trees? water. is it a lake? not a lake, though there are plenty round here; that is salt water, not fresh. look away to the right, and you see it through the opening of the woods again and again: and now look above the woods. you see a faint blue line, and gray and purple lumps like clouds, which rest upon it far away. that, child, is the great atlantic ocean, and those are islands in the far west. the water which washes the bottom of the lawn was but a few months ago pouring out of the gulf of mexico, between the bahamas and florida, and swept away here as the great ocean river of warm water which we call the gulf stream, bringing with it out of the open ocean the shoals of mackerel, and the porpoises and whales which feed upon them. some fine afternoon we will run down the bay and catch strange fishes, such as you never saw before, and very likely see a living whale. what? such a whale as they get whalebone from, and which eats sea-moths? no, they live far north, in the arctic circle; these are grampuses, and bottle-noses, which feed on fish; not so big as the right whales, but quite big enough to astonish you, if one comes up and blows close to the boat. get yourself dressed and come down, and then we will go out; we shall have plenty to see and talk of at every step. now, you have finished your breakfast at last, so come along, and we shall see what we shall see. first run out across the gravel, and scramble up that bank of lawn, and you will see what you fancied was an empty flower-bed. why, it is all hard rock. ah, you are come into the land of rocks now: out of the land of sand and gravel; out of a soft young corner of the world into a very hard, old, weather-beaten corner; and you will see rocks enough, and too many for the poor farmers, before you go home again. but how beautifully smooth and flat the rock is: and yet it is all rounded. what is it like? like--like the half of a shell. not badly said, but think again. like--like--i know what it is like. like the back of some great monster peeping up through the turf. you have got it. such rocks as these are called in switzerland "roches moutonnees," because they are, people fancy, like sheep's backs. now look at the cracks and layers in it. they run across the stone; they have nothing to do with the shape of it. you see that? yes: but here are cracks running across them, all along the stone, till the turf hides them. look at them again; they are no cracks; they do not go into the stone. i see. they are scratched; something like those on the elder-stem at home, where the cats sharpen their claws. but it would take a big cat to make them. do you recollect what i told you of madam how's hand, more flexible than any hand of man, and yet strong enough to grind the mountains into paste? i know. ice! ice! ice! but are these really ice-marks? child, on the place where we now stand, over rich lawns, and warm woods, and shining lochs, lay once on a time hundreds, it may be thousands, of feet of solid ice, crawling off yonder mountain-tops into the ocean there outside; and this is one of its tracks. see how the scratches all point straight down the valley, and straight out to sea. those mountains are feet high: but they were much higher once; for the ice has planed the tops off them. then, it seems to me, the ice sank, and left the mountains standing out of it about half their height, and at that level it stayed, till it had planed down all those lower moors of smooth bare rock between us and the western ocean; and then it sank again, and dwindled back, leaving moraines (that is, heaps of dirt and stones) all up these valleys here and there, till at the last it melted all away, and poor old ireland became fit to live in again. we will go down the bay some day and look at those moraines, some of them quite hills of earth, and then you will see for yourself how mighty a chisel the ice-chisel was, and what vast heaps of chips it has left behind. now then, down over the lawn towards the bridge. listen to the river, louder and louder every step we take. what a roar! is there a waterfall there? no. it is only the flood. and underneath the roar of that flood, do you not hear a deeper note--a dull rumbling, as if from underground? yes. what is it? the rolling of great stones under water, which are being polished against each other, as they hurry toward the sea. now, up on the parapet of the bridge. i will hold you tight. look and see madam how's rain-spade at work. look at the terrible yellow torrent below us, almost filling up the arches of the bridge, and leaping high in waves and crests of foam. oh, the bridge is falling into the water! not a bit. you are not accustomed to see water running below you at ten miles an hour. never mind that feeling. it will go off in a few seconds. look; the water is full six feet up the trunks of the trees; over the grass and the king fern, and the tall purple loose-strife-- oh! here comes a tree dancing down! and there are some turfs which have been cut on the mountain. and there is a really sad sight. look what comes now. one--two--three. why, they are sheep. yes. and a sad loss they will be to some poor fellow in the glen above. and oh! look at the pig turning round and round solemnly in the corner under the rock. poor piggy! he ought to have been at home safe in his stye, and not wandering about the hills. and what are these coming now? butter firkins, i think. yes. this is a great flood. it is well if there are no lives lost. but is it not cruel of madam how to make such floods? well--let us ask one of these men who are looking over the bridge. why, what does he say? i cannot understand one word. is he talking irish? irish-english at least: but what he said was, that it was a mighty fine flood entirely, praised be god; and would help on the potatoes and oats after the drought, and set the grass growing again on the mountains. and what is he saying now? that the river will be full of salmon and white trout after this. what does he mean? that under our feet now, if we could see through the muddy water, dozens of salmon and sea-trout are running up from the sea. what! up this furious stream? yes. what would be death to you is pleasure and play to them. up they are going, to spawn in the little brooks among the mountains; and all of them are the best of food, fattened on the herrings and sprats in the sea outside, madam how's free gift, which does not cost man a farthing, save the expense of nets and rods to catch them. how can that be? i will give you a bit of political economy. suppose a pound of salmon is worth a shilling; and a pound of beef is worth a shilling likewise. before we can eat the beef, it has cost perhaps tenpence to make that pound of beef out of turnips and grass and oil-cake; and so the country is only twopence a pound richer for it. but mr. salmon has made himself out of what he eats in the sea, and so has cost nothing; and the shilling a pound is all clear gain. there--you don't quite understand that piece of political economy. indeed, it is only in the last two or three years that older heads than yours have got to understand it, and have passed the wise new salmon laws, by which the rivers will be once more as rich with food as the land is, just as they were hundreds of years ago. but now, look again at the river. what do you think makes it so yellow and muddy? dirt, of course. and where does that come from? off the mountains? yes. tons on tons of white mud are being carried down past us now; and where will they go? into the sea? yes, and sink there in the still water, to make new strata at the bottom; and perhaps in them, ages hence, some one will find the bones of those sheep, and of poor mr. pig too, fossil-- and the butter firkins too. what fun to find a fossil butter firkin! but now lift up your eyes to the jagged mountain crests, and their dark sides all laced with silver streams. out of every crack and cranny there aloft, the rain is bringing down dirt, and stones too, which have been split off by the winter's frosts, deepening every little hollow, and sharpening every peak, and making the hills more jagged and steep year by year. when the ice went away, the hills were all scraped smooth and round by the glaciers, like the flat rock upon the lawn; and ugly enough they must have looked, most like great brown buns. but ever since then, madam how has been scooping them out again by her water-chisel into deep glens, mighty cliffs, sharp peaks, such as you see aloft, and making the old hills beautiful once more. why, even the alps in switzerland have been carved out by frost and rain, out of some great flat. the very peak of the matterhorn, of which you have so often seen a picture, is but one single point left of some enormous bun of rock. all the rest has been carved away by rain and frost; and some day the matterhorn itself will be carved away, and its last stone topple into the glacier at its foot. see, as we have been talking, we have got into the woods. oh, what beautiful woods, just like our own. not quite. there are some things growing here which do not grow at home, as you will soon see. and there are no rocks at home, either, as there are here. how strange, to see trees growing out of rocks! how do their roots get into the stone? there is plenty of rich mould in the cracks for them to feed on-- "health to the oak of the mountains; he trusts to the might of the rock-clefts. deeply he mines, and in peace feeds on the wealth of the stone." how many sorts of trees there are--oak, and birch and nuts, and mountain- ash, and holly and furze, and heather. and if you went to some of the islands in the lake up in the glen, you would find wild arbutus--strawberry-tree, as you call it. we will go and get some one day or other. how long and green the grass is, even on the rocks, and the ferns, and the moss, too. everything seems richer here than at home. of course it is. you are here in the land of perpetual spring, where frost and snow seldom, or never comes. oh, look at the ferns under this rock! i must pick some. pick away. i will warrant you do not pick all the sorts. yes. i have got them all now. not so hasty, child; there is plenty of a beautiful fern growing among that moss, which you have passed over. look here. what! that little thing a fern! hold it up to the light, and see. what a lovely little thing, like a transparent sea-weed, hung on black wire. what is it? film fern, hymenophyllum. but what are you staring at now, with all your eyes? oh! that rock covered with green stars and a cloud of little white and pink flowers growing out of them. aha! my good little dog! i thought you would stand to that game when you found it. what is it, though? you must answer that yourself. you have seen it a hundred times before. why, it is london pride, that grows in the garden at home. of course it is: but the irish call it st. patrick's cabbage; though it got here a long time before st. patrick; and st. patrick must have been very short of garden-stuff if he ever ate it. but how did it get here from london? no, no. how did it get to london from hence? for from this country it came. i suppose the english brought it home in queen bess's or james the first's time. but if it is wild here, and will grow so well in england, why do we not find it wild in england too? for the same reason that there are no toads or snakes in ireland. they had not got as far as ireland before ireland was parted off from england. and st. patrick's cabbage, and a good many other plants, had not got as far as england. but why? why, i don't know. but this i know: that when madam how makes a new sort of plant or animal, she starts it in one single place, and leaves it to take care of itself and earn its own living--as she does you and me and every one--and spread from that place all round as far as it can go. so st. patrick's cabbage got into this south-west of ireland, long, long ago; and was such a brave sturdy little plant, that it clambered up to the top of the highest mountains, and over all the rocks. but when it got to the rich lowlands to the eastward, in county cork, it found all the ground taken up already with other plants; and as they had enough to do to live themselves, they would not let st. patrick's cabbage settle among them; and it had to be content with living here in the far-west--and, what was very sad, had no means of sending word to its brothers and sisters in the pyrenees how it was getting on. what do you mean? are you making fun of me? not the least. i am only telling you a very strange story, which is literally true. come, and sit down on this bench. you can't catch that great butterfly, he is too strong on the wing for you. but oh, what a beautiful one! yes, orange and black, silver and green, a glorious creature. but you may see him at home sometimes: that plant close to you, you cannot see at home. why, it is only great spurge, such as grows in the woods at home. no. it is irish spurge which grows here, and sometimes in devonshire, and then again in the west of europe, down to the pyrenees. don't touch it. our wood spurge is poisonous enough, but this is worse still; if you get a drop of its milk on your lip or eye, you will be in agonies for half a day. that is the evil plant with which the poachers kill the salmon. how do they do that? when the salmon are spawning up in the little brooks, and the water is low, they take that spurge, and grind it between two stones under water, and let the milk run down into the pool; and at that all the poor salmon turn up dead. then comes the water-bailiff, and catches the poachers. then comes the policeman, with his sword at his side and his truncheon under his arm: and then comes a "cheap journey" to tralee gaol, in which those foolish poachers sit and reconsider themselves, and determine not to break the salmon laws--at least till next time. but why is it that this spurge, and st. patrick's cabbage, grow only here in the west? if they got here of themselves, where did they come from? all outside there is sea; and they could not float over that. come, i say, and sit down on this bench, and i will tell you a tale,--the story of the old atlantis, the sunken land in the far west. old plato, the greek, told legends of it, which you will read some day; and now it seems as if those old legends had some truth in them, after all. we are standing now on one of the last remaining scraps of the old atlantic land. look down the bay. do you see far away, under, the mountains, little islands, long and low? oh, yes. some of these are old slate, like the mountains; others are limestone; bits of the old coral-reef to the west of ireland which became dry land. i know. you told me about it. then that land, which is all eaten up by the waves now, once joined ireland to cornwall, and to spain, and to the azores, and i suspect to the cape of good hope, and what is stranger, to labrador, on the coast of north america. oh! how can you know that? listen, and i will give you your first lesson in what i call bio-geology. what a long word! if you can find a shorter one i shall be very much obliged to you, for i hate long words. but what it means is,--telling how the land has changed in shape, by the plants and animals upon it. and if you ever read (as you will) mr. wallace's new book on the indian archipelago, you will see what wonderful discoveries men may make about such questions if they will but use their common sense. you know the common pink heather--ling, as we call it? of course. then that ling grows, not only here and in the north and west of europe, but in the azores too; and, what is more strange, in labrador. now, as ling can neither swim nor fly, does not common sense tell you that all those countries were probably joined together in old times? well: but it seems so strange. so it is, my child; and so is everything. but, as the fool says in shakespeare-- "a long time ago the world began, with heigh ho, the wind and the rain." and the wind and the rain have made strange work with the poor old world ever since. and that is about all that we, who are not very much wiser than shakespeare's fool, can say about the matter. but again--the london pride grows here, and so does another saxifrage very like it, which we call saxifraga geum. now, when i saw those two plants growing in the western pyrenees, between france and spain, and with them the beautiful blue butterwort, which grows in these kerry bogs--we will go and find some--what could i say but that spain and ireland must have been joined once? i suppose it must be so. again. there is a little pink butterwort here in the bogs, which grows, too, in dear old devonshire and cornwall; and also in the south-west of scotland. now, when i found that too, in the bogs near biarritz, close to the pyrenees, and knew that it stretched away along the spanish coast, and into portugal, what could my common sense lead me to say but that scotland, and ireland, and cornwall, and spain were all joined once? those are only a few examples. i could give you a dozen more. for instance, on an island away there to the west, and only in one spot, there grows a little sort of lily, which is found i believe in brittany, and on the spanish and portuguese heaths, and even in north-west africa. and that africa and spain were joined not so very long ago at the straits of gibraltar there is no doubt at all. but where did the mediterranean sea run out then? perhaps it did not run out at all; but was a salt-water lake, like the caspian, or the dead sea. perhaps it ran out over what is now the sahara, the great desert of sand, for, that was a sea-bottom not long ago. but then, how was this land of atlantis joined to the cape of good hope? i cannot say how, or when either. but this is plain: the place in the world where the most beautiful heaths grow is the cape of good hope? you know i showed you cape heaths once at the nursery gardener's at home. oh yes, pink, and yellow, and white; so much larger than ours. then it seems (i only say it seems) as if there must have been some land once to the westward, from which the different sorts of heath spread south-eastward to the cape, and north-eastward into europe. and that they came north-eastward into europe seems certain; for there are no heaths in america or asia. but how north-eastward? think. stand with your face to the south and think. if a thing comes from the south-west--from there, it must go to the north-east-towards there. must it not? oh yes, i see. now then--the farther you go south-west, towards spain, the more kinds of heath there are, and the handsomer; as if their original home, from which they started, was somewhere down there. more sorts! what sorts? how many sorts of heath have we at home? three, of course: ling, and purple heath, and bottle heath. and there are no more in all england, or wales, or scotland, except--now, listen. in the very farthest end of cornwall there are two more sorts, the cornish heath and the orange-bell; and they say (though i never saw it) that the orange-bell grows near bournemouth. well. that is south and west too. so it is: but that makes five heaths. now in the south and west of ireland all these five heaths grow, and two more: the great irish heath, with purple bells, and the mediterranean heath, which flowers in spring. oh, i know them. they grow in the rhododendron beds at home. of course. now again. if you went down to spain, you would find all those seven heaths, and other sorts with them, and those which are rare in england and ireland are common there. about biarritz, on the spanish frontier, all the moors are covered with cornish heath, and the bogs with orange-bell, and lovely they are to see; and growing among them is a tall heath six feet high, which they call there _bruyere_, or broomheath, because they make brooms of it: and out of its roots the "briar-root" pipes are made. there are other heaths about that country, too, whose names i do not know; so that when you are there, you fancy yourself in the very home of the heaths: but you are not. they must have come from some land near where the azores are now; or how could heaths have got past africa, and the tropics, to the cape of good hope? it seems very wonderful, to be able to find out that there was a great land once in the ocean all by a few little heaths. not by them only, child. there are many other plants, and animals too, which make one think that so it must have been. and now i will tell you something stranger still. there may have been a time--some people say that there must--when africa and south america were joined by land. africa and south america! was that before the heaths came here, or after? i cannot tell: but i think, probably after. but this is certain, that there must have been a time when figs, and bamboos, and palms, and sarsaparillas, and many other sorts of plants could get from africa to america, or the other way, and indeed almost round the world. about the south of france and italy you will see one beautiful sarsaparilla, with hooked prickles, zigzagging and twining about over rocks and ruins, trunks and stems: and when you do, if you have understanding, it will seem as strange to you as it did to me to remember that the home of the sarsaparillas is not in europe, but in the forests of brazil, and the river plate. oh, i have heard about their growing there, and staining the rivers brown, and making them good medicine to drink: but i never thought there were any in europe. there are only one or two, and how they got there is a marvel indeed. but now--if there was not dry land between africa and south america, how did the cats get into america? for they cannot swim. cats? people might have brought them over. jaguars and pumas, which you read of in captain mayne reid's books, are cats, and so are the ocelots or tiger cats. oh, i saw them at the zoological gardens. but no one would bring them over, i should think, except to put them in the zoo. not unless they were very foolish. and much stronger and cleverer than the savages of south america. no, those jaguars and pumus have been in america for ages: and there are those who will tell you--and i think they have some reason on their side--that the jaguar, with his round patches of spots, was once very much the same as the african and indian leopard, who can climb trees well. so when he got into the tropic forests of america, he took to the trees, and lived among the branches, feeding on sloths and monkeys, and never coming to the ground for weeks, till he grew fatter and stronger and far more terrible than his forefathers. and they will tell you, too, that the puma was, perhaps--i only say perhaps--something like the lion, who (you know) has no spots. but when he got into the forests, he found very little food under the trees, only a very few deer; and so he was starved, and dwindled down to the poor little sheep-stealing rogue he is now, of whom nobody is afraid. oh, yes! i remember now a. said he and his men killed six in one day. but do you think it is all true about the pumas and jaguars? my child, i don't say that it is true: but only that it is likely to be true. in science we must be cautious and modest, and ready to alter our minds whenever we learn fresh facts; only keeping sure of one thing, that the truth, when we find it out, will be far more wonderful than any notions of ours. see! as we have been talking we have got nearly home: and luncheon must be ready. * * * * * why are you opening your eyes at me like the dog when he wants to go out walking? because i want to go out. but i don't want to go out walking. i want to go in the yacht. in the yacht? it does not belong to me. oh, that is only fun. i know everybody is going out in it to see such a beautiful island full of ferns, and have a picnic on the rocks; and i know you are going. then you know more than i do myself. but i heard them say you were going. then they know more than i do myself. but would you not like to go? i might like to go very much indeed; but as i have been knocked about at sea a good deal, and perhaps more than i intend to be again, it is no novelty to me, and there might be other things which i liked still better: for instance, spending the afternoon with you. then am i not to go? i think not. don't pull such a long face: but be a man, and make up your mind to it, as the geese do to going barefoot. but why may i not go? because i am not madam how, but your daddy. what can that have to do with it? if you asked madam how, do you know what she would answer in a moment, as civilly and kindly as could be? she would say--oh yes, go by all means, and please yourself, my pretty little man. my world is the paradise which the irishman talked of, in which "a man might do what was right in the sight of his own eyes, and what was wrong too, as he liked it." then madam how would let me go in the yacht? of course she would, or jump overboard when you were in it; or put your finger in the fire, and your head afterwards; or eat irish spurge, and die like the salmon; or anything else you liked. nobody is so indulgent as madam how: and she would be the dearest old lady in the world, but for one ugly trick that she has. she never tells any one what is coming, but leaves them to find it out for themselves. she lets them put their fingers in the fire, and never tells them that they will get burnt. but that is very cruel and treacherous of her. my boy, our business is not to call hard names, but to take things as we find them, as the highlandman said when he ate the braxy mutton. now shall i, because i am your daddy, tell you what madam how would not have told you? when you get on board the yacht, you will think it all very pleasant for an hour, as long as you are in the bay. but presently you will get a little bored, and run about the deck, and disturb people, and want to sit here, there, and everywhere, which i should not like. and when you get beyond that headland, you will find the great rollers coming in from the atlantic, and the cutter tossing and heaving as you never felt before, under a burning sun. and then my merry little young gentleman will begin to feel a little sick; and then very sick, and more miserable than he ever felt in his life; and wish a thousand times over that he was safe at home, even doing sums in long division; and he will give a great deal of trouble to various kind ladies--which no one has a right to do, if he can help it. of course i do not wish to be sick: only it looks such beautiful weather. and so it is: but don't fancy that last night's rain and wind can have passed without sending in such a swell as will frighten you, when you see the cutter climbing up one side of a wave, and running down the other; madam how tells me that, though she will not tell you yet. then why do they go out? because they are accustomed to it. they have come hither all round from cowes, past the land's end, and past cape clear, and they are not afraid or sick either. but shall i tell you how you would end this evening?--at least so i suspect. lying miserable in a stuffy cabin, on a sofa, and not quite sure whether you were dead or alive, till you were bundled into a boat about twelve o'clock at night, when you ought to be safe asleep, and come home cold, and wet, and stupid, and ill, and lie in bed all to- morrow. but will they be wet and cold? i cannot be sure; but from the look of the sky there to westward, i think some of them will be. so do you make up your mind to stay with me. but if it is fine and smooth to-morrow, perhaps we may row down the bay, and see plenty of wonderful things. but why is it that madam how will not tell people beforehand what will happen to them, as you have told me? now i will tell you a great secret, which, alas! every one has not found out yet. madam how will teach you, but only by experience. lady why will teach you, but by something very different--by something which has been called--and i know no better names for it--grace and inspiration; by putting into your heart feelings which no man, not even your father and mother, can put there; by making you quick to love what is right, and hate what is wrong, simply because they are right and wrong, though you don't know why they are right and wrong; by making you teachable, modest, reverent, ready to believe those who are older and wiser than you when they tell you what you could never find out for yourself: and so you will be prudent, that is provident, foreseeing, and know what will happen if you do so-and-so; and therefore what is really best and wisest for you. but why will she be kind enough to do that for me? for the very same reason that i do it. for god's sake. because god is your father in heaven, as i am your father on earth, and he does not wish his little child to be left to the hard teaching of nature and law, but to be helped on by many, many unsought and undeserved favours, such as are rightly called "means of grace;" and above all by the gospel and good news that you are god's child, and that god loves you, and has helped and taught you, and will help you and teach you, in a thousand ways of which you are not aware, if only you will be a wise child, and listen to lady why, when she cries from her palace of wisdom, and the feast which she has prepared, "whoso is simple let him turn in hither;" and says to him who wants understanding--"come, eat of my bread, and drink of the wine which i have mingled." "counsel is mine, and sound wisdom: i am understanding; i have strength. by me kings reign, and princes decree justice. by me princes rule, and nobles, even all the judges of the earth. i love them that love me; and those that seek me early shall find me. riches and honour are with me; yea, durable riches and righteousness." yes, i will try and listen to lady why: but what will happen if i do not? that will happen to you, my child--but god forbid it ever should happen--which happens to wicked kings and rulers, and all men, even the greatest and cleverest, if they do not choose to reign by lady why's laws, and decree justice according to her eternal ideas of what is just, but only do what seems pleasant and profitable to themselves. on them lady why turns round, and says--for she, too, can be awful, ay dreadful, when she needs-- "because i have called, and ye refused; i have stretched out my hand, and no man regarded; but ye have set at nought all my counsel, and would have none of my reproof--" and then come words so terrible, that i will not speak them here in this happy place: but what they mean is this:-- that these foolish people are handed over--as you and i shall be if we do wrong wilfully--to madam how and her terrible school-house, which is called nature and the law, to be treated just as the plants and animals are treated, because they did not choose to behave like men and children of god. and there they learn, whether they like or not, what they might have learnt from lady why all along. they learn the great law, that as men sow so they will reap; as they make their bed so they will lie on it: and madam how can teach that as no one else can in earth or heaven: only, unfortunately for her scholars, she is apt to hit so hard with her rod, which is called experience, that they never get over it; and therefore most of those who will only be taught by nature and law are killed, poor creatures, before they have learnt their lesson; as many a savage tribe is destroyed, ay and great and mighty nations too--the old roman empire among them. and the poor jews, who were carried away captive to babylon? yes; they would not listen to lady why, and so they were taken in hand by madam how, and were seventy years in her terrible school-house, learning a lesson which, to do them justice, they never forgot again. but now we will talk of something pleasanter. we will go back to lady why, and listen to her voice. it sounds gentle and cheerful enough just now. listen. what? is she speaking to us now? hush! open your eyes and ears once more, for you are growing sleepy with my long sermon. watch the sleepy shining water, and the sleepy green mountains. listen to the sleepy lapping of the ripple, and the sleepy sighing of the woods, and let lady why talk to you through them in "songs without words," because they are deeper than all words, till you, too, fall asleep with your head upon my knee. but what does she say? she says--"be still. the fulness of joy is peace." there, you are fast asleep; and perhaps that is the best thing for you; for sleep will (so i am informed, though i never saw it happen, nor any one else) put fresh gray matter into your brain; or save the wear and tear of the old gray matter; or something else--when they have settled what it is to do: and if so, you will wake up with a fresh fiddle-string to your little fiddle of a brain, on which you are playing new tunes all day long. so much the better: but when i believe that your brain is you, pretty boy, then i shall believe also that the fiddler is his fiddle. chapter xii--homeward bound come: i suppose you consider yourself quite a good sailor by now? oh, yes. i have never been ill yet, though it has been quite rough again and again. what you call rough, little man. but as you are grown such a very good sailor, and also as the sea is all but smooth, i think we will have a sail in the yacht to-day, and that a tolerably long one. oh, how delightful! but i thought we were going home; and the things are all packed up. and why should we not go homewards in the yacht, things and all? what, all the way to england? no, not so far as that; but these kind people, when they came into the harbour last night, offered to take us up the coast to a town, where we will sleep, and start comfortably home to-morrow morning. so now you will have a chance of seeing something of the great sea outside, and of seeing, perhaps, the whale himself. i hope we shall see the whale. the men say he has been outside the harbour every day this week after the fish. very good. now do you keep quiet, and out of the way, while we are getting ready to go on board; and take a last look at this pretty place, and all its dear kind people. and the dear kind dogs too, and the cat and the kittens. * * * * * now, come along, and bundle into the boat, if you have done bidding every one good-bye; and take care you don't slip down in the ice-groovings, as you did the other day. there, we are off at last. oh, look at them all on the rock watching us and waving their handkerchiefs; and harper and paddy too, and little jimsy and isy, with their fat bare feet, and their arms round the dogs' necks. i am so sorry to leave them all. not sorry to go home? no, but--they have been so kind; and the dogs were so kind. i am sure they knew we were going, and were sorry too. perhaps they were. they knew we were going away, at all events. they know what bringing out boxes and luggage means well enough. sam knew, i am sure; but he did not care for us. he was only uneasy because he thought harper was going, and he should lose his shooting; and as soon as he saw harper was not getting into the boat, he sat down and scratched himself, quite happy. but do dogs think? of course they do, only they do not think in words, as we do. but how can they think without words? that is very difficult for you and me to imagine, because we always think in words. they must think in pictures, i suppose, by remembering things which have happened to them. you and i do that in our dreams. i suspect that savages, who have very few words to express their thoughts with, think in pictures, like their own dogs. but that is a long story. we must see about getting on board now, and under way. * * * * * well, and what have you been doing? oh, i looked all over the yacht, at the ropes and curious things; and then i looked at the mountains, till i was tired; and then i heard you and some gentleman talking about the land sinking, and i listened. there was no harm in that? none at all. but what did you hear him say? that the land must be sinking here, because there were peat-bogs everywhere below high-water mark. is that true? quite true; and that peat would never have been formed where the salt water could get at it, as it does now every tide. but what was it he said about that cliff over there? he said that cliff on our right, a hundred feet high, was plainly once joined on to that low island on our left. what, that long bank of stones, with a house on it? that is no house. that is a square lump of mud, the last remaining bit of earth which was once the moraine of a glacier. every year it crumbles into the sea more and more; and in a few years it will be all gone, and nothing left but the great round boulder-stones which the ice brought down from the glaciers behind us. but how does he know that it was once joined to the cliff? because that cliff, and the down behind it, where the cows are fed, is made up, like the island, of nothing but loose earth and stones; and that is why it is bright and green beside the gray rocks and brown heather of the moors at its foot. he knows that it must be an old glacier moraine; and he has reason to think that moraine once stretched right across the bay to the low island, and perhaps on to the other shore, and was eaten out by the sea as the land sank down. but how does he know that the land sank? of that, he says, he is quite certain; and this is what he says.--suppose there was a glacier here, where we are sailing now: it would end in an ice cliff, such as you have seen a picture of in captain cook's voyages, of which you are so fond. you recollect the pictures of christmas sound and possession bay? oh yes, and pictures of greenland and spitzbergen too, with glaciers in the sea. then icebergs would break off from that cliff, and carry all the dirt and stones out to sea, perhaps hundreds of miles away, instead of letting it drop here in a heap; and what did fall in a heap here the sea would wash down at once, and smooth it over the sea-bottom, and never let it pile up in a huge bank like that. do you understand? i think i do. therefore, he says, that great moraine must have been built upon dry land, in the open air; and must have sunk since into the sea, which is gnawing at it day and night, and will some day eat it all up, as it would eat up all the dry land in the world, if madam how was not continually lifting up fresh land, to make up for what the sea has carried off. oh, look there! some one has caught a fish, and is hauling it up. what a strange creature! it is not a mackerel, nor a gurnet, nor a pollock. how do you know that? why, it is running along the top of the water like a snake; and they never do that. here it comes. it has got a long beak, like a snipe. oh, let me see. see if you like: but don't get in the way. remember you are but a little boy. what is it? a snake with a bird's head? no: a snake has no fins; and look at its beak: it is full of little teeth, which no bird has. but a very curious fellow he is, nevertheless: and his name is gar-fish. some call him green-bone, because his bones are green. but what kind of fish is he? he is like nothing i ever saw. i believe he is nearest to a pike, though his backbone is different from a pike, and from all other known fishes. but is he not very rare? oh no: he comes to devonshire and cornwall with the mackerel, as he has come here; and in calm weather he will swim on the top of the water, and play about, and catch flies, and stand bolt upright with his long nose in the air; and when the fisher-boys throw him a stick, he will jump over it again and again, and play with it in the most ridiculous way. and what will they do with him? cut him up for bait, i suppose, for he is not very good to eat. certainly, he does smell very nasty. have you only just found out that? sometimes when i have caught one, he has made the boat smell so that i was glad to throw him overboard, and so he saved his life by his nastiness. but they will catch plenty of mackerel now; for where he is they are; and where they are, perhaps the whale will be; for we are now well outside the harbour, and running across the open bay; and lucky for you that there are no rollers coming in from the atlantic, and spouting up those cliffs in columns of white foam. * * * * * "hoch!" ah! who was that coughed just behind the ship? who, indeed? look round and see. there is nobody. there could not be in the sea. look--there, a quarter of a mile away. oh! what is that turning over in the water, like a great black wheel? and a great tooth on it, and--oh! it is gone! never mind. it will soon show itself again. but what was it? the whale: one of them, at least; for the men say there are two different ones about the bay. that black wheel was part of his back, as he turned down; and the tooth on it was his back-fin. but the noise, like a giant's cough? rather like the blast of a locomotive just starting. that was his breath. what? as loud as that? why not? he is a very big fellow, and has big lungs. how big is he? i cannot say: perhaps thirty or forty feet long. we shall be able to see better soon. he will come up again, and very likely nearer us, where those birds are. i don't want him to come any nearer. you really need not be afraid. he is quite harmless. but he might run against the yacht. he might: and so might a hundred things happen which never do. but i never heard of one of these whales running against a vessel; so i suppose he has sense enough to know that the yacht is no concern of his, and to keep out of its way. but why does he make that tremendous noise only once, and then go under water again? you must remember that he is not a fish. a fish takes the water in through his mouth continually, and it runs over his gills, and out behind through his gill-covers. so the gills suck-up the air out of the water, and send it into the fish's blood, just as they do in the newt-larva. yes, i know. but the whale breathes with lungs like you and me; and when he goes under water he has to hold his breath, as you and i have. what a long time he can hold it. yes. he is a wonderful diver. some whales, they say, will keep under for an hour. but while he is under, mind, the air in his lungs is getting foul, and full of carbonic acid, just as it would in your lungs, if you held your breath. so he is forced to come up at last: and then out of his blowers, which are on the top of his head, he blasts out all the foul breath, and with it the water which has got into his mouth, in a cloud of spray. then he sucks in fresh air, as much as he wants, and dives again, as you saw him do just now. and what does he do under water? look--and you will see. look at those birds. we will sail up to them; for mr. whale will probably rise among them soon. oh, what a screaming and what a fighting! how many sorts there are! what are those beautiful little ones, like great white swallows, with crested heads and forked tails, who hover, and then dip down and pick up something? terns--sea-swallows. and there are gulls in hundreds, you see, large and small, gray-backed and black-backed; and over them all two or three great gannets swooping round and round. oh! one has fallen into the sea! yes, with a splash just like a cannon ball. and here he comes up again, with a fish in his beak. if he had fallen on your head, with that beak of his, he would have split it open. i have heard of men catching gannets by tying a fish on a board, and letting it float; and when the gannet strikes at it he drives his bill into the board, and cannot get it out. but is not that cruel? i think so. gannets are of no use, for eating, or anything else. what a noise! it is quite deafening. and what are those black birds about, who croak like crows, or parrots? look at them. some have broad bills, with a white stripe on it, and cry something like the moor-hens at home. those are razor-bills. and what are those who say "marrock," something like a parrot? the ones with thin bills? they are guillemots, "murres" as we call them in devon: but in some places they call them "marrocks," from what they say. and each has a little baby bird swimming behind it. oh! there: the mother has cocked up her tail and dived, and the little one is swimming about looking for her! how it cries! it is afraid of the yacht. and there she comes up again, and cries "marrock" to call it. look at it swimming up to her, and cuddling to her, quite happy. quite happy. and do you not think that any one who took a gun and shot either that mother or that child would be both cowardly and cruel? but they might eat them. these sea-birds are not good to eat. they taste too strong of fish-oil. they are of no use at all, except that the gulls' and terns' feathers are put into girls' hats. well they might find plenty of other things to put in their hats. so i think. yes: it would be very cruel, very cruel indeed, to do what some do, shoot at these poor things, and leave them floating about wounded till they die. but i suppose, if one gave them one's mind about such doings, and threatened to put the new sea fowl act in force against them, and fine them, and show them up in the newspapers, they would say they meant no harm, and had never thought about its being cruel. then they ought to think. they ought; and so ought you. half the cruelty in the world, like half the misery, comes simply from people's not thinking; and boys are often very cruel from mere thoughtlessness. so when you are tempted to rob birds' nests, or to set the dogs on a moorhen, or pelt wrens in the hedge, think; and say--how should i like that to be done to me? i know: but what are all the birds doing? look at the water, how it sparkles. it is alive with tiny fish, "fry," "brett" as we call them in the west, which the mackerel are driving up to the top. poor little things! how hard on them! the big fish at them from below, and the birds at them from above. and what is that? thousands of fish leaping out of the water, scrambling over each other's backs. what a curious soft rushing roaring noise they make! aha! the eaters are going to be eaten in turn. those are the mackerel themselves; and i suspect they see mr. whale, and are scrambling out of the way as fast as they can, lest he should swallow them down, a dozen at a time. look out sharp for him now. i hope he will not come very near. no. the fish are going from us and past us. if he comes up, he will come up astern of us, so look back. there he is! that? i thought it was a boat. yes. he does look very like a boat upside down. but that is only his head and shoulders. he will blow next. "hoch!" oh! what a jet of spray, like the geysers! and the sun made a rainbow on the top of it. he is quite still now. yes; he is taking a long breath or two. you need not hold my hand so tight. his head is from us; and when he goes down he will go right away. oh, he is turning head over heels! there is his back fin again. and--ah! was that not a slap! how the water boiled and foamed; and what a tail he had! and how the mackerel flew out of the water! yes. you are a lucky boy to have seen that. i have not seen one of those gentlemen show his "flukes," as they call them, since i was a boy on the cornish coast. where is he gone? hunting mackerel, away out at sea. but did you notice something odd about his tail, as you call it--though it is really none? it looked as if it was set on flat, and not upright, like a fish's. but why is it not a tail? just because it is set on flat, not upright: and learned men will tell you that those two flukes are the "rudiments"--that is, either the beginning, or more likely the last remains--of two hind feet. but that belongs to the second volume of madam how's book of kind; and you have not yet learned any of the first volume, you know, except about a few butterflies. look here! here are more whales coming. don't be frightened. they are only little ones, mackerel-hunting, like the big one. what pretty smooth things, turning head over heels, and saying, "hush, hush!" they don't really turn clean over; and that "hush" is their way of breathing. are they the young ones of that great monster? no; they are porpoises. that big one is, i believe, a bottle-nose. but if you want to know about the kinds of whales, you must ask dr. flower at the royal college of surgeons, and not me: and he will tell you wonderful things about them.--how some of them have mouths full of strong teeth, like these porpoises; and others, like the great sperm whale in the south sea, have huge teeth in their lower jaws, and in the upper only holes into which those teeth fit; others like the bottle-nose, only two teeth or so in the lower jaw; and others, like the narwhal, two straight tusks in the upper jaw, only one of which grows, and is what you call a narwhal's horn. oh yes. i know of a walking-stick made of one. and strangest of all, how the right-whales have a few little teeth when they are born, which never come through the gums; but, instead, they grow all along their gums, an enormous curtain of clotted hair, which serves as a net to keep in the tiny sea-animals on which they feed, and let the water strain out. you mean whalebone? is whalebone hair? so it seems. and so is a rhinoceros's horn. a rhinoceros used to be hairy all over in old times: but now he carries all his hair on the end of his nose, except a few bristles on his tail. and the right-whale, not to be done in oddity, carries all his on his gums. but have no whales any hair? no real whales: but the manati, which is very nearly a whale, has long bristly hair left. don't you remember m.'s letter about the one he saw at rio janeiro? this is all very funny: but what is the use of knowing so much about things' teeth and hair? what is the use of learning latin and greek, and a dozen things more which you have to learn? you don't know yet: but wiser people than you tell you that they will be of use some day. and i can tell you, that if you would only study that gar-fish long enough, and compare him with another fish something like him, who has a long beak to his lower jaw, and none to his upper--and how he eats i cannot guess,--and both of them again with certain fishes like them, which m. agassiz has found lately, not in the sea, but in the river amazon; and then think carefully enough over their bones and teeth, and their history from the time they are hatched--why, you would find out, i believe, a story about the river amazon itself, more wonderful than all the fairy tales you ever read. now there is luncheon ready. come down below, and don't tumble down the companion-stairs; and by the time you have eaten your dinner we shall be very near the shore. * * * * * so? here is my little man on deck, after a good night's rest. and he has not been the least sick, i hear. not a bit: but the cabin was so stuffy and hot, i asked leave to come on deck. what a huge steamer! but i do not like it as well as the yacht. it smells of oil and steam, and-- and pigs and bullocks too, i am sorry to say. don't go forward above them, but stay here with me, and look round. where are we now? what are those high hills, far away to the left, above the lowlands and woods? those are the shore of the old world--the welsh mountains. and in front of us i can see nothing but flat land. where is that? that is the mouth of the severn and avon; where we shall be in half an hour more. and there, on the right, over the low hills, i can see higher ones, blue and hazy. those are an island of the old world, called now the mendip hills; and we are steaming along the great strait between the mendips and the welsh mountains, which once was coral reef, and is now the severn sea; and by the time you have eaten your breakfast we shall steam in through a crack in that coral-reef; and you will see what you missed seeing when you went to ireland, because you went on board at night. * * * * * oh! where have we got to now? where is the wide severn sea? two or three miles beyond us; and here we are in narrow little avon. narrow indeed. i wonder that the steamer does not run against those rocks. but how beautiful they are, and how the trees hang down over the water, and are all reflected in it! yes. the gorge of the avon is always lovely. i saw it first when i was a little boy like you; and i have seen it many a time since, in sunshine and in storm, and thought it more lovely every time. look! there is something curious. what? those great rusty rings fixed into the rock? yes. those may be as old, for aught i know, as queen elizabeth's or james's reign. but why were they put there? for ships to hold on by, if they lost the tide. what do you mean? it is high tide now. that is why the water is almost up to the branches of the trees. but when the tide turns, it will all rush out in a torrent which would sweep ships out to sea again, if they had not steam, as we have, to help them up against the stream. so sailing ships, in old times, fastened themselves to those rings, and rode against the stream till the tide turned, and carried them up to bristol. but what is the tide? and why does it go up and down? and why does it alter with the moon, as i heard you all saying so often in ireland? that is a long story, which i must tell you something about some other time. now i want you to look at something else: and that is, the rocks themselves, in which the rings are. they are very curious in my eyes, and very valuable; for they taught me a lesson in geology when i was quite a boy: and i want them to teach it to you now. what is there curious in them? this. you will soon see for yourself, even from the steamer's deck, that they are not the same rock as the high limestone hills above. they are made up of red sand and pebbles; and they are a whole world younger, indeed some say two worlds younger, than the limestone hills above, and lie upon the top of the limestone. now you may see what i meant when i said that the newer rocks, though they lie on the top of the older, were often lower down than they are. but how do you know that they lie on the limestone? look into that corner of the river, as we turn round, and you will see with your own eyes. there are the sandstones, lying flat on the turned- up edges of another rock. yes; i see. the layers of it are almost upright. then that upright rock underneath is part of the great limestone hill above. so the hill must have been raised out of the sea, ages ago, and eaten back by the waves; and then the sand and pebbles made a beach at its foot, and hardened into stone; and there it is. and when you get through the limestone hills to bristol, you will see more of these same red sandstone rocks, spread about at the foot of the limestone-hills, on the other side. but why is the sandstone two worlds newer than the limestone? because between that sandstone and that limestone come hundreds of feet of rock, which carry in them all the coal in england. don't you remember that i told you that once before? oh yes. but i see no coal between them there. no. but there is plenty of coal between them over in wales; and plenty too between them on the other side of bristol. what you are looking at there is just the lip of a great coal-box, where the bottom and the lid join. the bottom is the mountain limestone; and the lid is the new red sandstone, or trias, as they call it now: but the coal you cannot see. it is stowed inside the box, miles away from here. but now, look at the cliffs and the downs, which (they tell me) are just like the downs in the holy land; and the woods and villas, high over your head. and what is that in the air? a bridge? yes--that is the famous suspension bridge--and a beautiful work of art it is. ay, stare at it, and wonder at it, little man, of course. but is it not wonderful? yes: it was a clever trick to get those chains across the gulf, high up in the air: but not so clever a trick as to make a single stone of which those piers are built, or a single flower or leaf in those woods. the more you see of madam how's masonry and carpentry, the clumsier man's work will look to you. but now we must get ready to give up our tickets, and go ashore, and settle ourselves in the train; and then we shall have plenty to see as we run home; more curious, to my mind, than any suspension bridge. and you promised to show me all the different rocks and soils as we went home, because it was so dark when we came from reading. very good. * * * * * now we are settled in the train. and what do you want to know first? more about the new rocks being lower than the old ones, though they lie on the top of them. well, look here, at this sketch. a boy piling up slates? what has that to do with it? i saw you in ireland piling slates against a rock just in this way. and i thought to myself--"that is something like madam how's work." how? why, see. the old rock stands for the mountains of the old world, like the welsh mountains, or the mendip hills. the slates stand for the new rocks, which have been piled up against these, one over the other. but, you see, each slate is lower than the one before it, and slopes more; till the last slate which you are putting on is the lowest of all, though it overlies all. i see now. i see now. then look at the sketch of the rocks between this and home. it is only a rough sketch, of course: but it will make you understand something more about the matter. now. you see, the lump marked a. with twisted lines in it. that stands for the mendip hills to the west, which are made of old red sandstone, very much the same rock (to speak roughly) as the kerry mountains. and why are the lines in it twisted? to show that the strata, the layers in it, are twisted, and set up at quite different angles from the limestone. but how was that done? by old earthquakes and changes which happened in old worlds, ages on ages since. then the edges of the old red sandstone were eaten away by the sea--and some think by ice too, in some earlier age of ice; and then the limestone coral reef was laid down on them, "unconformably," as geologists say--just as you saw the new red sandstone laid down on the edges of the limestone; and so one world is built up on the edge of another world, out of its scraps and ruins. then do you see b. with a notch in it? that means these limestone hills on the shoulder of the mendips; and that notch is the gorge of the avon which we have steamed through. and what is that black above it? that is the coal, a few miles off, marked c. and what is this d, which comes next? that is what we are on now. new red sandstone, lying unconformably on the coal. i showed it you in the bed of the river, as we came along in the cab. we are here in a sort of amphitheatre, or half a one, with the limestone hills around us, and the new red sandstone plastered on, as it were, round the bottom of it inside. but what is this high bit with e against it? those are the high hills round bath, which we shall run through soon. they are newer than the soil here; and they are (for an exception) higher too; for they are so much harder than the soil here, that the sea has not eaten them away, as it has all the lowlands from bristol right into the somersetshire flats. * * * * * there. we are off at last, and going to run home to reading, through one of the loveliest lines (as i think) of old england. and between the intervals of eating fruit, we will geologize on the way home, with this little bit of paper to show us where we are. what pretty rocks! yes. they are a boss of the coal measures, i believe, shoved up with the lias, the lias lying round them. but i warn you i may not be quite right: because i never looked at a geological map of this part of the line, and have learnt what i know, just as i want you to learn simply by looking out of the carriage window. look. here is lias rock in the side of the cutting; layers of hard blue limestone, and then layers of blue mud between them, in which, if you could stop to look, you would find fossils in plenty; and along that lias we shall run to bath, and then all the rocks will change. * * * * * now, here we are at bath; and here are the handsome fruit-women, waiting for you to buy. and oh, what strawberries and cherries! yes. all this valley is very rich, and very sheltered too, and very warm; for the soft south-western air sweeps up it from the bristol channel; so the slopes are covered with fruit-orchards, as you will see as you get out of the station. why, we are above the tops of the houses. yes. we have been rising ever since we left bristol; and you will soon see why. now we have laid in as much fruit as is safe for you, and away we go. oh, what high hills over the town! and what beautiful stone houses! even the cottages are built of stone. all that stone comes out of those high hills, into which we are going now. it is called bath-stone freestone, or oolite; and it lies on the top of the lias, which we have just left. here it is marked f. what steep hills, and cliffs too, and with quarries in them! what can have made them so steep? and what can have made this little narrow valley? madam how's rain-spade from above, i suppose, and perhaps the sea gnawing at their feet below. those freestone hills once stretched high over our heads, and far away, i suppose, to the westward. now they are all gnawed out into cliffs,--indeed gnawed clean through in the bottom of the valley, where the famous hot springs break out in which people bathe. is that why the place is called bath? of course. but the old romans called the place aquae solis--the waters of the sun; and curious old roman remains are found here, which we have not time to stop and see. now look out at the pretty clear limestone stream running to meet us below, and the great limestone hills closing over us above. how do you think we shall get out from among them? shall we go over their tops? no. that would be too steep a climb, for even such a great engine as this. then there is a crack which we can get through? look and see. why, we are coming to a regular wall of hill, and-- and going right through it in the dark. we are in the box tunnel. * * * * * there is the light again: and now i suppose you will find your tongue. how long it seemed before we came out! yes, because you were waiting and watching, with nothing to look at: but the tunnel is only a mile and a quarter long after all, i believe. if you had been looking at fields and hedgerows all the while, you would have thought no time at all had passed. what curious sandy rocks on each side of the cutting, in lines and layers. those are the freestone still: and full of fossils they are. but do you see that they dip away from us? remember that. all the rocks are sloping eastward, the way we are going; and each new rock or soil we come to lies on the top of the one before it. now we shall run down hill for many a mile, down the back of the oolites, past pretty chippenham, and wootton-bassett, towards swindon spire. look at the country, child; and thank god for this fair english land, in which your lot is cast. what beautiful green fields; and such huge elm trees; and orchards; and flowers in the cottage gardens! ay, and what crops, too: what wheat and beans, turnips and mangold. all this land is very rich and easily worked; and hereabouts is some of the best farming in england. the agricultural college at cirencester, of which you have so often heard, lies thereaway, a few miles to our left; and there lads go to learn to farm as no men in the world, save english and scotch, know how to farm. but what rock are we on now? on rock that is much softer than that on the other side of the oolite hills: much softer, because it is much newer. we have got off the oolites on to what is called the oxford clay; and then, i believe, on to the coral rag, and on that again lies what we are coming to now. do you see the red sand in that field? then that is the lowest layer of a fresh world, so to speak; a world still younger than the oolites--the chalk world. but that is not chalk, or anything like it. no, that is what is called greensand. but it is not green, it is red. i know: but years ago it got the name from one green vein in it, in which the "coprolites," as you learnt to call them at cambridge, are found; and that, and a little layer of blue clay, called gault, between the upper greensand and lower greensand, runs along everywhere at the foot of the chalk hills. i see the hills now. are they chalk? yes, chalk they are: so we may begin to feel near home now. see how they range away to the south toward devizes, and westbury, and warminster, a goodly land and large. at their feet, everywhere, run the rich pastures on which the wiltshire cheese is made; and here and there, as at westbury, there is good iron-ore in the greensand, which is being smelted now, as it used to be in the weald of surrey and kent ages since. i must tell you about that some other time. but are there coprolites here? i believe there are: i know there are some at swindon; and i do not see why they should not be found, here and there, all the way along the foot of the downs, from here to cambridge. but do these downs go to cambridge? of course they do. we are now in the great valley which runs right across england from south-west to north-east, from axminster in devonshire to hunstanton in norfolk, with the chalk always on your right hand, and the oolite hills on your left, till it ends by sinking into the sea, among the fens of lincolnshire and norfolk. but what made that great valley? i am not learned enough to tell. only this i think we can say--that once on a time these chalk downs on our right reached high over our heads here, and far to the north; and that madam how pared them away, whether by icebergs, or by sea-waves, or merely by rain, i cannot tell. well, those downs do look very like sea-cliffs. so they do, very like an old shore-line. be that as it may, after the chalk was eaten away, madam how began digging into the soils below the chalk, on which we are now; and because they were mostly soft clays, she cut them out very easily, till she came down, or nearly down, to the harder freestone rocks which run along on our left hand, miles away; and so she scooped out this great vale, which we call here the vale of white horse; and further on, the vale of aylesbury; and then the bedford level; and then the dear ugly old fens. is this the vale of white horse? oh, i know about it; i have read _the scouring of the white horse_. of course you have; and when you are older you will read a jollier book still,--_tom brown's school days_--and when we have passed swindon, we shall see some of the very places described in it, close on our right. * * * * * there is the white horse hill. the white horse hill? but where is the horse? i can see a bit of him: but he does not look like a horse from here, or indeed from any other place; he is a very old horse indeed, and a thousand years of wind and rain have spoilt his anatomy a good deal on the top of that wild down. and is that really where alfred fought the danes? as certainly, boy, i believe, as that waterloo is where the duke fought napoleon. yes: you may well stare at it with all your eyes, the noble down. it is one of the most sacred spots on english soil. ah, it is gone now. the train runs so fast. so it does; too fast to let you look long at one thing: but in return, it lets you see so many more things in a given time than the slow old coaches and posters did.--well? what is it? i wanted to ask you a question, but you won't listen to me. won't i? i suppose i was dreaming with my eyes open. you see, i have been so often along this line--and through this country, too, long before the line was made--that i cannot pass it without its seeming full of memories--perhaps of ghosts. of real ghosts? as real ghosts, i suspect, as any one on earth ever saw; faces and scenes which have printed themselves so deeply on one's brain, that when one passes the same place, long years after, they start up again, out of fields and roadsides, as if they were alive once more, and need sound sense to send them back again into their place as things which are past for ever, for good and ill. but what did you want to know? why, i am so tired of looking out of the window. it is all the same: fields and hedges, hedges and fields; and i want to talk. fields and hedges, hedges and fields? peace and plenty, plenty and peace. however, it may seem dull, now that the grass is cut; but you would not have said so two months ago, when the fields were all golden- green with buttercups, and the whitethorn hedges like crested waves of snow. i should like to take a foreigner down the vale of berkshire in the end of may, and ask him what he thought of old england. but what shall we talk about? i want to know about coprolites, if they dig them here, as they do at cambridge. i don't think they do. but i suspect they will some day. but why do people dig them? because they are rational men, and want manure for their fields. but what are coprolites? well, they were called coprolites at first because some folk fancied they were the leavings of fossil animals, such as you may really find in the lias at lynn in dorsetshire. but they are not that; and all we can say is, that a long time ago, before the chalk began to be made, there was a shallow sea in england, the shore of which was so covered with dead animals, that the bone-earth (the phosphate of lime) out of them crusted itself round every bone, and shell, and dead sea-beast on the shore, and got covered up with fresh sand, and buried for ages as a mine of wealth. but how many millions of dead creatures, there must have been! what killed them? we do not know. no more do we know how it comes to pass that this thin band (often only a few inches thick) of dead creatures should stretch all the way from dorsetshire to norfolk, and, i believe, up through lincolnshire. and what is stranger still, this same bone-earth bed crops out on the south side of the chalk at farnham, and stretches along the foot of those downs, right into kent, making the richest hop lands in england, through surrey, and away to tunbridge. so that it seems as if the bed lay under the chalk everywhere, if once we could get down to it. but how does it make the hop lands so rich? because hops, like tobacco and vines, take more phosphorus out of the soil than any other plants which we grow in england; and it is the washings of this bone-earth bed which make the lower lands in farnham so unusually rich, that in some of them--the garden, for instance, under the bishop's castle--have grown hops without resting, i believe, for three hundred years. but who found out all this about the coprolites? ah--i will tell you; and show you how scientific men, whom ignorant people sometimes laugh at as dreamers, and mere pickers up of useless weeds and old stones, may do real service to their country and their countrymen, as i hope you will some day. there was a clergyman named henslow, now with god, honoured by all scientific men, a kind friend and teacher of mine, loved by every little child in his parish. his calling was botany: but he knew something of geology. and some of these coprolites were brought him as curiosities, because they had fossils in them. but he (so the tale goes) had the wit to see that they were not, like other fossils, carbonate of lime, but phosphate of lime--bone earth. whereon he told the neighbouring farmers that they had a mine of wealth opened to them, if they would but use them for manure. and after a while he was listened to. then others began to find them in the eastern counties; and then another man, as learned and wise as he was good and noble--john paine of farnham, also now with god--found them on his own estate, and made much use and much money of them: and now tens of thousands of pounds' worth of valuable manure are made out of them every year, in cambridgeshire and bedfordshire, by digging them out of land which was till lately only used for common farmers' crops. but how do they turn coprolites into manure? i used to see them in the railway trucks at cambridge, and they were all like what i have at home--hard pebbles. they grind them first in a mill. then they mix them with sulphuric acid and water, and that melts them down, and parts them into two things. one is sulphate of lime (gypsum, as it is commonly called), and which will not dissolve in water, and is of little use. but the other is what is called superphosphate of lime, which will dissolve in water; so that the roots of the plants can suck it up: and that is one of the richest of manures. oh, i know: you put superphosphate on the grass last year. yes. but not that kind; a better one still. the superphosphate from the copiolites is good; but the superphosphate from fresh bones is better still, and therefore dearer, because it has in it the fibrine of the bones, which is full of nitrogen, like gristle or meat; and all that has been washed out of the bone-earth bed ages and ages ago. but you must learn some chemistry to understand that. i should like to be a scientific man, if one can find out such really useful things by science. child, there is no saying what you might find out, or of what use you may be to your fellow-men. a man working at science, however dull and dirty his work may seem at times, is like one of those "chiffoniers," as they call them in paris--people who spend their lives in gathering rags and sifting refuse, but who may put their hands at any moment upon some precious jewel. and not only may you be able to help your neighbours to find out what will give them health and wealth: but you may, if you can only get them to listen to you, save them from many a foolish experiment, which ends in losing money just for want of science. i have heard of a man who, for want of science, was going to throw away great sums (i believe he, luckily for him, never could raise the money) in boring for coal in our bagshot sands at home. the man thought that because there was coal under the heather moors in the north, there must needs be coal here likewise, when a geologist could have told him the contrary. there was another man at hennequin's lodge, near the wellington college, who thought he would make the poor sands fertile by manuring them with whale oil, of all things in the world. so he not only lost all the cost of his whale oil, but made the land utterly barren, as it is unto this day; and all for want of science. and i knew a manufacturer, too, who went to bore an artesian well for water, and hired a regular well-borer to do it. but, meanwhile he was wise enough to ask a geologist of those parts how far he thought it was down to the water. the geologist made his calculations, and said: "you will go through so many feet of bagshot sand; and so many feet of london clay; and so many feet of the thanet beds between them and the chalk: and then you will win water, at about feet; but not, i think, till then." the well-sinker laughed at that, and said, "he had no opinion of geologists, and such-like. he never found any clay in england but what he could get through in feet." so he began to bore-- feet, , : and then he began to look rather silly; at last, at --only seven feet short of what the geologist had foretold--up came the water in a regular spout. but, lo and behold, not expecting to have to bore so deep, he had made his bore much too small; and the sand out of the thanet beds "blew up" into the bore, and closed it. the poor manufacturer spent hundreds of pounds more in trying to get the sand out, but in vain; and he had at last to make a fresh and much larger well by the side of the old one, bewailing the day when he listened to the well-sinker and not to the geologist, and so threw away more than a thousand pounds. and there is an answer to what you asked on board the yacht--what use was there in learning little matters of natural history and science, which seemed of no use at all? and now, look out again. do you see any change in the country? what? why, there to the left. there are high hills there now, as well as to the right. what are they? chalk hills too. the chalk is on both sides of us now. these are the chilterns, all away to ipsden and nettlebed, and so on across oxfordshire and buckinghamshire, and into hertfordshire; and on again to royston and cambridge, while below them lies the vale of aylesbury; you can just see the beginning of it on their left. a pleasant land are those hills, and wealthy; full of noble houses buried in the deep beech-woods, which once were a great forest, stretching in a ring round the north of london, full of deer and boar, and of wild bulls too, even as late as the twelfth century, according to the old legend of thomas a becket's father and the fair saracen, which you have often heard. i know. but how are you going to get through the chalk hills? is there a tunnel as there is at box and at micheldever? no. something much prettier than a tunnel and something which took a great many years longer in making. we shall soon meet with a very remarkable and famous old gentleman, who is a great adept at digging, and at landscape gardening likewise; and he has dug out a path for himself through the chalk, which we shall take the liberty of using also. and his name, if you wish to know it, is father thames. i see him. what a great river! yes. here he comes, gleaming and winding down from oxford, over the lowlands, past wallingford; but where he is going to it is not so easy to see. ah, here is chalk in the cutting at last. and what a high bridge. and the river far under our feet. why we are crossing him again! yes; he winds more sharply than a railroad can. but is not this prettier than a tunnel? oh, what hanging-woods, and churches; and such great houses, and pretty cottages and gardens--all in this narrow crack of a valley! ay. old father thames is a good landscape gardener, as i said. there is basildon--and hurley--and pangbourne, with its roaring lasher. father thames has had to work hard for many an age before he could cut this trench right through the chalk, and drain the water out of the flat vale behind us. but i suspect the sea helped him somewhat, or perhaps a great deal, just where we are now. the sea? yes. the sea was once--and that not so very long ago--right up here, beyond reading. this is the uppermost end of the great thames valley, which must have been an estuary--a tide flat, like the mouth of the severn, with the sea eating along at the foot of all the hills. and if the land sunk only some fifty feet,--which is a very little indeed, child, in this huge, ever-changing world,--then the tide would come up to reading again, and the greater part of london and the county of middlesex be drowned in salt water. how dreadful that would be! dreadful indeed. god grant that it may never happen. more terrible changes of land and water have happened, and are happening still in the world: but none, i think, could happen which would destroy so much civilisation and be such a loss to mankind, as that the thames valley should become again what it was, geologically speaking, only the other day, when these gravel banks, over which we are running to reading, were being washed out of the chalk cliffs up above at every tide, and rolled on a beach, as you have seen them rolling still at ramsgate. now here we are at reading. there is the carriage waiting, and away we are off home; and when we get home, and have seen everybody and everything, we will look over our section once more. but remember, that when you ran through the chalk hills to reading, you passed from the bottom of the chalk to the top of it, on to the thames gravels, which lie there on the chalk, and on to the london clay, which lies on the chalk also, with the thames gravels always over it. so that, you see, the newest layers, the london clay and the gravels, are lower in height than the limestone cliffs at bristol, and much lower than the old mountain ranges of devonshire and wales, though in geological order they are far higher; and there are whole worlds of strata, rocks and clays, one on the other, between the thames gravels and the devonshire hills. but how about our moors? they are newer still, you said, than the london clay, because they lie upon it: and yet they are much higher than we are here at reading. very well said: so they are, two or three hundred feet higher. but our part of them was left behind, standing up in banks, while the valley of the thames was being cut out by the sea. once they spread all over where we stand now, and away behind us beyond newbury in berkshire, and away in front of us, all over where london now stands. how can you tell that? because there are little caps--little patches--of them left on the tops of many hills to the north of london; just remnants which the sea, and the thames, and the rain have not eaten down. probably they once stretched right out to sea, sloping slowly under the waves, where the mouth of the thames is now. you know the sand-cliffs at bournemouth? of course. then those are of the same age as the bagshot sands, and lie on the london clay, and slope down off the new forest into the sea, which eats them up, as you know, year by year and day by day. and here were once perhaps cliffs just like them, where london bridge now stands. * * * * * there, we are rumbling away home at last, over the dear old heather-moors. how far we have travelled--in our fancy at least--since we began to talk about all these things, upon the foggy november day, and first saw madam how digging at the sand-banks with her water-spade. how many countries we have talked of; and what wonderful questions we have got answered, which all grew out of the first question, how were the heather-moors made? and yet we have not talked about a hundredth part of the things about which these very heather-moors ought to set us thinking. but so it is, child. those who wish honestly to learn the laws of madam how, which we call nature, by looking honestly at what she does, which we call fact, have only to begin by looking at the very smallest thing, pin's head or pebble, at their feet, and it may lead them--whither, they cannot tell. to answer any one question, you find you must answer another; and to answer that you must answer a third, and then a fourth; and so on for ever and ever. for ever and ever? of course. if we thought and searched over the universe--ay, i believe, only over this one little planet called earth--for millions on millions of years, we should not get to the end of our searching. the more we learnt, the more we should find there was left to learn. all things, we should find, are constituted according to a divine and wonderful order, which links each thing to every other thing; so that we cannot fully comprehend any one thing without comprehending all things: and who can do that, save he who made all things? therefore our true wisdom is never to fancy that we do comprehend: never to make systems and theories of the universe (as they are called) as if we had stood by and looked on when time and space began to be; but to remember that those who say they understand, show, simply by so saying, that they understand nothing at all; that those who say they see, are sure to be blind; while those who confess that they are blind, are sure some day to see. all we can do is, to keep up the childlike heart, humble and teachable, though we grew as wise as newton or as humboldt; and to follow, as good socrates bids us, reason whithersoever it leads us, sure that it will never lead us wrong, unless we have darkened it by hasty and conceited fancies of our own, and so have become like those foolish men of old, of whom it was said that the very light within them was darkness. but if we love and reverence and trust fact and nature, which are the will, not merely of madam how, or even of lady why, but of almighty god himself, then we shall be really loving, and reverencing, and trusting god; and we shall have our reward by discovering continually fresh wonders and fresh benefits to man; and find it as true of science, as it is of this life and of the life to come--that eye hath not seen, nor ear heard, nor hath it entered into the heart of man to conceive, what god has prepared for those who love him. footnotes { } i could not resist the temptation of quoting this splendid generalisation from dr. carpenter's preliminary report of the dredging operations of h.m.s. "lightening," . he attributes it, generously, to his colleague, dr. wyville thomson. be it whose it may, it will mark (as will probably the whole report when completed) a new era in bio-geology. none geological contemporaneity and persistent types of life. by thomas h. huxley [ ] merchants occasionally go through a wholesome, though troublesome and not always satisfactory, process which they term "taking stock." after all the excitement of speculation, the pleasure of gain, and the pain of loss, the trader makes up his mind to face facts and to learn the exact quantity and quality of his solid and reliable possessions. the man of science does well sometimes to imitate this procedure; and, forgetting for the time the importance of his own small winnings, to re-examine the common stock in trade, so that he may make sure how far the stock of bullion in the cellar--on the faith of whose existence so much paper has been circulating--is really the solid gold of truth. the anniversary meeting of the geological society seems to be an occasion well suited for an undertaking of this kind--for an inquiry, in fact, into the nature and value of the present results of paleontological investigation; and the more so, as all those who have paid close attention to the late multitudinous discussions in which paleontology is implicated, must have felt the urgent necessity of some such scrutiny. first in order, as the most definite and unquestionable of all the results of paleontology, must be mentioned the immense extension and impulse given to botany, zoology, and comparative anatomy, by the investigation of fossil remains. indeed, the mass of biological facts has been so greatly increased, and the range of biological speculation has been so vastly widened, by the researches of the geologist and paleontologist, that it is to be feared there are naturalists in existence who look upon geology as brindley regarded rivers. "rivers," said the great engineer, "were made to feed canals"; and geology, some seem to think, was solely created to advance comparative anatomy. were such a thought justifiable, it could hardly expect to be received with favour by this assembly. but it is not justifiable. your favourite science has her own great aims independent of all others; and if, notwithstanding her steady devotion to her own progress, she can scatter such rich alms among her sisters, it should be remembered that her charity is of the sort that does not impoverish, but "blesseth him that gives and him that takes." regard the matter as we will, however, the facts remain. nearly , species of animals and plants have been added to the systema naturae by paleontologic research. this is a living population equivalent to that of a new continent in mere number; equivalent to that of a new hemisphere, if we take into account the small population of insects as yet found fossil, and the large proportion and peculiar organization of many of the vertebrata. but, beyond this, it is perhaps not too much to say that, except for the necessity of interpreting paleontologic facts, the laws of distribution would have received less careful study; while few comparative anatomists (and those not of the first order) would have been induced by mere love of detail, as such, to study the minutiae of osteology, were it not that in such minutiae lie the only keys to the most interesting riddles offered by the extinct animal world. these assuredly are great and solid gains. surely it is matter for no small congratulation that in half a century (for paleontology, though it dawned earlier, came into full day only with cuvier) a subordinate branch of biology should have doubled the value and the interest of the whole group of sciences to which it belongs. but this is not all. allied with geology, paleontology has established two laws of inestimable importance: the first, that one and the same area of the earth's surface has been successively occupied by very different kinds of living beings; the second, that the order of succession established in one locality holds good, approximately, in all. the first of these laws is universal and irreversible; the second is an induction from a vast number of observations, though it may possibly, and even probably, have to admit of exceptions. as a consequence of the second law, it follows that a peculiar relation frequently subsists between series of strata, containing organic remains, in different localities. the series resemble one another, not only in virtue of a general resemblance of the organic remains in the two, but also in virtue of a resemblance in the order and character of the serial succession in each. there is a resemblance of arrangement; so that the separate terms of each series, as well as the whole series, exhibit a correspondence. succession implies time; the lower members of a series of sedimentary rocks are certainly older than the upper; and when the notion of age was once introduced as the equivalent of succession, it was no wonder that correspondence in succession came to be looked upon as a correspondence in age, or "contemporaneity." and, indeed, so long as relative age only is spoken of, correspondence in succession 'is' correspondence in age; it is 'relative' contemporaneity. but it would have been very much better for geology if so loose and ambiguous a word as "contemporaneous" had been excluded from her terminology, and if, in its stead, some term expressing similarity of serial relation, and excluding the notion of time altogether, had been employed to denote correspondence in position in two or more series of strata. in anatomy, where such correspondence of position has constantly to be spoken of, it is denoted by the word "homology" and its derivatives; and for geology (which after all is only the anatomy and physiology of the earth) it might be well to invent some single word, such as "homotaxis" (similarity of order), in order to express an essentially similar idea. this, however, has not been done, and most probably the inquiry will at once be made--to what end burden science with a new and strange term in place of one old, familiar, and part of our common language? the reply to this question will become obvious as the inquiry into the results of paleontology is pushed further. those whose business it is to acquaint themselves specially with the works of paleontologists, in fact, will be fully aware that very few, if any, would rest satisfied with such a statement of the conclusions of their branch of biology as that which has just been given. our standard repertories of paleontology profess to teach us far higher things--to disclose the entire succession of living forms upon the surface of the globe; to tell us of a wholly different distribution of climatic conditions in ancient times; to reveal the character of the first of all living existences; and to trace out the law of progress from them to us. it may not be unprofitable to bestow on these professions a somewhat more critical examination than they have hitherto received, in order to ascertain how far they rest on an irrefragable basis; or whether, after all, it might not be well for paleontologists to learn a little more carefully that scientific "ars artium," the art of saying "i don't know." and to this end let us define somewhat more exactly the extent of these pretensions of paleontology. every one is aware that professor bronn's 'untersuchungen' and professor pictet's 'traite de paleontologie' are works of standard authority, familiarly consulted by every working paleontologist. it is desirable to speak of these excellent books, and of their distinguished authors, with the utmost respect, and in a tone as far as possible removed from carping criticism; indeed, if they are specially cited in this place, it is merely in justification of the assertion that the following propositions, which may be found implicitly, or explicitly, in the works in question, are regarded by the mass of paleontologists and geologists, not only on the continent but in this country, as expressing some of the best-established results of paleontology. thus:-- animals and plants began their existence together, not long after the commencement of the deposition of the sedimentary rocks; and then succeeded one another, in such a manner, that totally distinct faunae and florae occupied the whole surface of the earth, one after the other, and during distinct epochs of time. a geological formation is the sum of all the strata deposited over the whole surface of the earth during one of these epochs: a geological fauna or flora is the sum of all the species of animals or plants which occupied the whole surface of the globe, during one of these epochs. the population of the earth's surface was at first very similar in all parts, and only from the middle of the tertiary epoch onwards, began to show a distinct distribution in zones. the constitution of the original population, as well as the numerical proportions of its members, indicates a warmer and, on the whole, somewhat tropical climate, which remained tolerably equable throughout the year. the subsequent distribution of living beings in zones is the result of a gradual lowering of the general temperature, which first began to be felt at the poles. it is not now proposed to inquire whether these doctrines are true or false; but to direct your attention to a much simpler though very essential preliminary question--what is their logical basis? what are the fundamental assumptions upon which they all logically depend? and what is the evidence on which those fundamental propositions demand our assent? these assumptions are two: the first, that the commencement of the geological record is coeval with the commencement of life on the globe; the second, that geological contemporaneity is the same thing as chronological synchrony. without the first of these assumptions there would of course be no ground for any statement respecting the commencement of life; without the second, all the other statements cited, every one of which implies a knowledge of the state of different parts of the earth at one and the same time, will be no less devoid of demonstration. the first assumption obviously rests entirely on negative evidence. this is, of course, the only evidence that ever can be available to prove the commencement of any series of phenomena; but, at the same time, it must be recollected that the value of negative evidence depends entirely on the amount of positive corroboration it receives. if a b wishes to prove an 'alibi', it is of no use for him to get a thousand witnesses simply to swear that they did not see him in such and such a place, unless the witnesses are prepared to prove that they must have seen him had he been there. but the evidence that animal life commenced with the lingula-flags, 'e.g.', would seem to be exactly of this unsatisfactory uncorroborated sort. the cambrian witnesses simply swear they "haven't seen anybody their way"; upon which the counsel for the other side immediately puts in ten or twelve thousand feet of devonian sandstones to make oath they never saw a fish or a mollusk, though all the world knows there were plenty in their time. but then it is urged that, though the devonian rocks in one part of the world exhibit no fossils, in another they do, while the lower cambrian rocks nowhere exhibit fossils, and hence no living being could have existed in their epoch. to this there are two replies: the first, that the observational basis of the assertion that the lowest rocks are nowhere fossiliferous is an amazingly small one, seeing how very small an area, in comparison to that of the whole world, has yet been fully searched; the second, that the argument is good for nothing unless the unfossiliferous rocks in question were not only 'contemporaneous' in the geological sense, but 'synchronous' in the chronological sense. to use the 'alibi' illustration again. if a man wishes to prove he was in neither of two places, a and b, on a given day, his witnesses for each place must be prepared to answer for the whole day. if they can only prove that he was not at a in the morning, and not at b in the afternoon, the evidence of his absence from both is 'nil', because he might have been at b in the morning and at a in the afternoon. thus everything depends upon the validity of the second assumption. and we must proceed to inquire what is the real meaning of the word "contemporaneous" as employed by geologists. to this end a concrete example may be taken. the lias of england and the lias of germany, the cretaceous rocks of britain and the cretaceous rocks of southern india, are termed by geologists "contemporaneous" formations; but whenever any thoughtful geologist is asked whether he means to say that they were deposited synchronously, he says, "no,--only within the same great epoch." and if, in pursuing the inquiry, he is asked what may be the approximate value in time of a "great epoch"--whether it means a hundred years, or a thousand, or a million, or ten million years--his reply is, "i cannot tell." if the further question be put, whether physical geology is in possession of any method by which the actual synchrony (or the reverse) of any two distant deposits can be ascertained, no such method can be heard of; it being admitted by all the best authorities that neither similarity of mineral composition, nor of physical character, nor even direct continuity of stratum, are 'absolute' proofs of the synchronism of even approximated sedimentary strata: while, for distant deposits, there seems to be no kind of physical evidence attainable of a nature competent to decide whether such deposits were formed simultaneously, or whether they possess any given difference of antiquity. to return to an example already given: all competent authorities will probably assent to the proposition that physical geology does not enable us in any way to reply to this question--were the british cretaceous rocks deposited at the same time as those of india, or are they a million of years younger or a million of years older? is paleontology able to succeed where physical geology fails? standard writers on paleontology, as has been seen, assume that she can. they take it for granted, that deposits containing similar organic remains are synchronous--at any rate in a broad sense; and yet, those who will study the eleventh and twelfth chapters of sir henry de la beche's remarkable 'researches in theoretical geology', published now nearly thirty years ago, and will carry out the arguments there most luminously stated, to their logical consequences, may very easily convince themselves that even absolute identity of organic contents is no proof of the synchrony of deposits, while absolute diversity is no proof of difference of date. sir henry de la beche goes even further, and adduces conclusive evidence to show that the different parts of one and the same stratum, having a similar composition throughout, containing the same organic remains, and having similar beds above and below it, may yet differ to any conceivable extent in age. edward forbes was in the habit of asserting that the similarity of the organic contents of distant formations was 'prima facie' evidence, not of their similarity, but of their difference of age; and holding as he did the doctrine of single specific centres, the conclusion was as legitimate as any other; for the two districts must have been occupied by migration from one of the two, or from an intermediate spot, and the chances against exact coincidence of migration and of imbedding are infinite. in point of fact, however, whether the hypothesis of single or of multiple specific centres be adopted, similarity of organic contents cannot possibly afford any proof of the synchrony of the deposits which contain them; on the contrary, it is demonstrably compatible with the lapse of the most prodigious intervals of time, and with the interposition of vast changes in the organic and inorganic worlds, between the epochs in which such deposits were formed. on what amount of similarity of their faunae is the doctrine of the contemporaneity of the european and of the north american silurians based? in the last edition of sir charles lyell's 'elementary geology' it is stated, on the authority of a former president of this society, the late daniel sharpe, that between and per cent. of the species of silurian mollusca are common to both sides of the atlantic. by way of due allowance for further discovery, let us double the lesser number and suppose that per cent. of the species are common to the north american and the british silurians. sixty per cent. of species in common is, then, proof of contemporaneity. now suppose that, a million or two of years hence, when britain has made another dip beneath the sea and has come up again, some geologist applies this doctrine, in comparing the strata laid bare by the upheaval of the bottom, say, of st. george's channel with what may then remain of the suffolk crag. reasoning in the same way, he will at once decide the suffolk crag and the st. george's channel beds to be contemporaneous; although we happen to know that a vast period (even in the geological sense) of time, and physical changes of almost unprecedented extent, separate the two. but if it be a demonstrable fact that strata containing more than or per cent. of species of mollusca in common, and comparatively close together, may yet be separated by an amount of geological time sufficient to allow of some of the greatest physical changes the world has seen, what becomes of that sort of contemporaneity the sole evidence of which is a similarity of facies, or the identity of half a dozen species, or of a good many genera? and yet there is no better evidence for the contemporaneity assumed by all who adopt the hypothesis of universal faunae and florae, of a universally uniform climate, and of a sensible cooling of the globe during geological time. there seems, then, no escape from the admission that neither physical geology, nor paleontology, possesses any method by which the absolute synchronism of two strata can be demonstrated. all that geology can prove is local order of succession. it is mathematically certain that, in any given vertical linear section of an undisturbed series of sedimentary deposits, the bed which lies lowest is the oldest. in many other vertical linear sections of the same series, of course, corresponding beds will occur in a similar order; but, however great may be the probability, no man can say with absolute certainty that the beds in the two sections were synchronously deposited. for areas of moderate extent, it is doubtless true that no practical evil is likely to result from assuming the corresponding beds to be synchronous or strictly contemporaneous; and there are multitudes of accessory circumstances which may fully justify the assumption of such synchrony. but the moment the geologist has to deal with large areas, or with completely separated deposits, the mischief of confounding that "homotaxis" or "similarity of arrangement," which 'can' be demonstrated, with "synchrony" or "identity of date," for which there is not a shadow of proof, under the one common term of "contemporaneity" becomes incalculable, and proves the constant source of gratuitous speculations. for anything that geology or paleontology are able to show to the contrary, a devonian fauna and flora in the british islands may have been contemporaneous with silurian life in north america, and with a carboniferous fauna and flora in africa. geographical provinces and zones may have been as distinctly marked in the paleozoic epoch as at present, and those seemingly sudden appearances of new genera and species, which we ascribe to new creation, may be simple results of migration. it may be so; it may be otherwise. in the present condition of our knowledge and of our methods, one verdict--"not proven, and not provable"--must be recorded against all the grand hypotheses of the paleontologist respecting the general succession of life on the globe. the order and nature of terrestrial life, as a whole, are open questions. geology at present provides us with most valuable topographical records, but she has not the means of working them into a universal history. is such a universal history, then, to be regarded as unattainable? are all the grandest and most interesting problems which offer themselves to the geological student essentially insoluble? is he in the position of a scientific tantalus--doomed always to thirst for a knowledge which he cannot obtain? the reverse is to be hoped; nay, it may not be impossible to indicate the source whence help will come. in commencing these remarks, mention was made of the great obligations under which the naturalist lies to the geologist and paleontologist. assuredly the time will come when these obligations will be repaid tenfold, and when the maze of the world's past history, through which the pure geologist and the pure paleontologist find no guidance, will be securely threaded by the clue furnished by the naturalist. all who are competent to express an opinion on the subject are, at present, agreed that the manifold varieties of animal and vegetable form have not either come into existence by chance, nor result from capricious exertions of creative power; but that they have taken place in a definite order, the statement of which order is what men of science term a natural law. whether such a law is to be regarded as an expression of the mode of operation of natural forces, or whether it is simply a statement of the manner in which a supernatural power has thought fit to act, is a secondary question, so long as the existence of the law and the possibility of its discovery by the human intellect are granted. but he must be a half-hearted philosopher who, believing in that possibility, and having watched the gigantic strides of the biological sciences during the last twenty years, doubts that science will sooner or later make this further step, so as to become possessed of the law of evolution of organic forms--of the unvarying order of that great chain of causes and effects of which all organic forms, ancient and modern, are the links. and then, if ever, we shall be able to begin to discuss, with profit, the questions respecting the commencement of life, and the nature of the successive populations of the globe, which so many seem to think are already answered. the preceding arguments make no particular claim to novelty; indeed they have been floating more or less distinctly before the minds of geologists for the last thirty years; and if, at the present time, it has seemed desirable to give them more definite and systematic expression, it is because paleontology is every day assuming a greater importance, and now requires to rest on a basis the firmness of which is thoroughly well assured. among its fundamental conceptions, there must be no confusion between what is certain and what is more or less probable. [ ] but, pending the construction of a surer foundation than paleontology now possesses, it may be instructive, assuming for the nonce the general correctness of the ordinary hypothesis of geological contemporaneity, to consider whether the deductions which are ordinarily drawn from the whole body of paleontologic facts are justifiable. the evidence on which such conclusions are based is of two kinds, negative and positive. the value of negative evidence, in connection with this inquiry, has been so fully and clearly discussed in an address from the chair of this society [ ], which none of us have forgotten, that nothing need at present be said about it; the more, as the considerations which have been laid before you have certainly not tended to increase your estimation of such evidence. it will be preferable to turn to the positive facts of paleontology, and to inquire what they tell us. we are all accustomed to speak of the number and the extent of the changes in the living population of the globe during geological time as something enormous: and indeed they are so, if we regard only the negative differences which separate the older rocks from the more modern, and if we look upon specific and generic changes as great changes, which from one point of view, they truly are. but leaving the negative differences out of consideration, and looking only at the positive data furnished by the fossil world from a broader point of view--from that of the comparative anatomist who has made the study of the greater modifications of animal form his chief business--a surprise of another kind dawns upon the mind; and under 'this' aspect the smallness of the total change becomes as astonishing as was its greatness under the other. there are two hundred known orders of plants; of these not one is certainly known to exist exclusively in the fossil state. the whole lapse of geological time has as yet yielded not a single new ordinal type of vegetable structure. [ ] the positive change in passing from the recent to the ancient animal world is greater, but still singularly small. no fossil animal is so distinct from those now living as to require to be arranged even in a separate class from those which contain existing forms. it is only when we come to the orders, which may be roughly estimated at about a hundred and thirty, that we meet with fossil animals so distinct from those now living as to require orders for themselves; and these do not amount, on the most liberal estimate, to more than about per cent. of the whole. there is no certainly known extinct order of protozoa; there is but one among the coelenterata--that of the rugose corals; there is none among the mollusca; there are three, the cystidea, blastoidea, and edrioasterida, among the echinoderms; and two, the trilobita and eurypterida, among the crustacea; making altogether five for the great sub-kingdom of annulosa. among vertebrates there is no ordinally distinct fossil fish: there is only one extinct order of amphibia--the labyrinthodonts; but there are at least four distinct orders of reptilia, viz. the ichthyosauria, plesiosauria, pterosauria, dinosauria, and perhaps another or two. there is no known extinct order of birds, and no certainly known extinct order of mammals, the ordinal distinctness of the "toxodontia" being doubtful. the objection that broad statements of this kind, after all, rest largely on negative evidence is obvious, but it has less force than may at first be supposed; for, as might be expected from the circumstances of the case, we possess more abundant positive evidence regarding fishes and marine mollusks than respecting any other forms of animal life; and yet these offer us, through the whole range of geological time, no species ordinally distinct from those now living; while the far less numerous class of echinoderms presents three; and the crustacea two, such orders, though none of these come down later than the paleozoic age. lastly, the reptilia present the extraordinary and exceptional phenomenon of as many extinct as existing orders, if not more; the four mentioned maintaining their existence from the lias to the chalk inclusive. some years ago one of your secretaries pointed out another kind of positive paleontologic evidence tending towards the same conclusion--afforded by the existence of what he termed "persistent types" of vegetable and of animal life. [ ] he stated, on the authority of dr. hooker, that there are carboniferous plants which appear to be generically identical with some now living; that the cone of the oolitic 'araucaria' is hardly distinguishable from that of an existing species; that a true 'pinus' appears in the purbecks, and a 'juglans' in the chalk; while, from the bagshot sands, a 'banksia', the wood of which is not distinguishable from that of species now living in australia, had been obtained. turning to the animal kingdom, he affirmed the tabulate corals of the silurian rocks to be wonderfully like those which now exist; while even the families of the aporosa were all represented in the older mesozoic rocks. among the molluska similar facts were adduced. let it be borne in mind that 'avicula', 'mytails', 'chiton', 'natica', 'patella', 'trochus', 'discina', 'orbicula', 'lingula', 'rhynchonella', and 'nautilus', all of which are existing 'genera', are given without a doubt as silurian in the last edition of 'siluria'; while the highest forms of the highest cephalopods are represented in the lias by a genus, 'belemnoteuthis', which presents the closest relation to the existing 'loligo'. the two highest groups of the annulosa, the insecta and the arachnida, are represented in the coal, either by existing genera, or by forms differing from existing genera in quite minor peculiarities. turning to the vertebrata, the only paleozoic elasmobranch fish of which we have any complete knowledge is the devonian and carboniferous 'pleuracanthus', which differs no more from existing sharks than these do from one another. again, vast as is the number of undoubtedly ganoid fossil fishes, and great as is their range in time, a large mass of evidence has recently been adduced to show that almost all those respecting which we possess sufficient information, are referable to the same sub-ordinal groups as the existing 'lepidosteus', 'polypterus', and sturgeon; and that a singular relation obtains between the older and the younger fishes; the former, the devonian ganoids, being almost all members of the same sub-order as 'polypterus', while the mesozoic ganoids are almost all similarly allied to 'lepidosteus'. [ ] again, what can be more remarkable than the singular constancy of structure preserved throughout a vast period of time by the family of the pycnodonts and by that of the true coelacanths; the former persisting, with but insignificant modifications, from the carboniferous to the tertiary rocks, inclusive; the latter existing, with still less change, from the carboniferous rocks to the chalk, inclusive? among reptiles, the highest living group, that of the crocodilia, is represented, at the early part of the mesozoic epoch, by species identical in the essential characters of their organization with those now living, and differing from the latter only in such matters as the form of the articular facets of the vertebral centra, in the extent to which the nasal passages are separated from the cavity of the mouth by bone, and in the proportions of the limbs. and even as regards the mammalia, the scanty remains of triassic and oolitic species afford no foundation for the supposition that the organization of the oldest forms differed nearly so much from some of those which now live as these differ from one another. it is needless to multiply these instances; enough has been said to justify the statement that, in view of the immense diversity of known animal and vegetable forms, and the enormous lapse of time indicated by the accumulation of fossiliferous strata, the only circumstance to be wondered at is, not that the changes of life, as exhibited by positive evidence, have been so great, but that they have been so small. be they great or small, however, it is desirable to attempt to estimate them. let us, therefore, take each great division of the animal world in succession, and, whenever an order or a family can be shown to have had a prolonged existence, let us endeavour to ascertain how far the later members of the group differ from the earlier ones. if these later members, in all or in many cases, exhibit a certain amount of modification, the fact is, so far, evidence in favour of a general law of change; and, in a rough way, the rapidity of that change will be measured by the demonstrable amount of modification. on the other hand, it must be recollected that the absence of any modification, while it may leave the doctrine of the existence of a law of change without positive support, cannot possibly disprove all forms of that doctrine, though it may afford a sufficient refutation of any of them. the protozoa.--the protozoa are represented throughout the whole range of geological series, from the lower silurian formation to the present day. the most ancient forms recently made known by ehrenberg are exceedingly like those which now exist: no one has ever pretended that the difference between any ancient and any modern foraminifera is of more than generic value, nor are the oldest foraminifera either simpler, more embryonic, or less differentiated, than the existing forms. the coelenterata.--the tabulate corals have existed from the silurian epoch to the present day, but i am not aware that the ancient 'heliolites' possesses a single mark of a more embryonic or less differentiated character, or less high organization, than the existing 'heliopora'. as for the aporose corals, in what respect is the silurian 'paleocyclus' less highly organized or more embryonic than the modern 'fungia', or the liassic aporosa than the existing members of the same families? the 'mollusca'.--in what sense is the living 'waldheimia' less embryonic, or more specialized; than the paleozoic 'spirifer'; or the existing 'rhynchonellae', 'craniae', 'discinae', 'lingulae', than the silurian species of the same genera? in what sense can 'loligo' or 'spirula' be said to be more specialized, or less embryonic, than 'belemnites'; or the modern species of lamellibranch and gasteropod genera, than the silurian species of the same genera? the annulosa.--the carboniferous insecta and arachnida are neither less specialized, nor more embryonic, than these that now live, nor are the liassic cirripedia and macrura; while several of the brachyura, which appear in the chalk, belong to existing genera; and none exhibit either an intermediate, or an embryonic, character. the vertebrara.--among fishes i have referred to the coelacanthini (comprising the genera 'coelacanthus', 'holophagus', 'undina', and 'macropoma') as affording an example of a persistent type; and it is most remarkable to note the smallness of the differences between any of these fishes (affecting at most the proportions of the body and fins, and the character and sculpture of the scales), notwithstanding their enormous range in time. in all the essentials of its very peculiar structure, the 'macropoma' of the chalk is identical with the 'coelacanthus' of the coal. look at the genus 'lepidotus', again, persisting without a modification of importance from the liassic to the eocene formations inclusive. or among the teleostei--in what respect is the 'beryx' of the chalk more embryonic, or less differentiated, than 'beryx lineatus' of king george's sound? or to turn to the higher vertebrata--in what sense are the liassic chelonia inferior to those which now exist? how are the cretaceous ichthyosauria, plesiosauria, or pterosauria less embryonic, or more differentiated, species than those of the lias? or lastly, in what circumstance is the 'phascolotherium' more embryonic, or of a more generalized type, than the modern opossum; or a 'lophiodon', or a 'paleotherium', than a modern 'tapirus' or 'hyrax'? these examples might be almost indefinitely multiplied, but surely they are sufficient to prove that the only safe and unquestionable testimony we can procure--positive evidence--fails to demonstrate any sort of progressive modification towards a less embryonic, or less generalised, type in a great many groups of animals of long-continued geological existence. in these groups there is abundant evidence of variation--none of what is ordinarily understood as progression; and, if the known geological record is to be regarded as even any considerable fragment of the whole, it is inconceivable that any theory of a necessarily progressive development can stand, for the numerous orders and families cited afford no trace of such a process. but it is a most remarkable fact, that, while the groups which have been mentioned, and many besides, exhibit no sign of progressive modification, there are others, co-existing with them, under the same conditions, in which more or less distinct indications of such a process seems to be traceable. among such indications i may remind you of the predominance of holostome gasteropoda in the older rocks as compared with that of siphonostome gasteropoda in the later. a case less open to the objection of negative evidence, however, is that afforded by the tetrabranchiate cephalopoda, the forms of the shells and of the septal sutures exhibiting a certain increase of complexity in the newer genera. here, however, one is met at once with the occurrence of 'orthoceras' and 'baculites' at the two ends of the series, and of the fact that one of the simplest genera, 'nautilus', is that which now exists. the crinoidea, in the abundance of stalked forms in the ancient formations as compared with their present rarity, seem to present us with a fair case of modification from a more embryonic towards a less embryonic condition. but then, on careful consideration of the facts, the objection arises that the stalk, calyx, and arms of the paleozoic crinoid are exceedingly different from the corresponding organs of a larval 'comatula'; and it might with perfect justice be argued that 'actinocrinus' and 'eucalyptocrinus', for example, depart to the full as widely, in one direction, from the stalked embryo of 'comatula', as 'comatula' itself does in the other. the echinidea, again, are frequently quoted as exhibiting a gradual passage from a more generalized to a more specialized type, seeing that the elongated, or oval, spatangoids appear after the spheroidal echinoids. but here it might be argued, on the other hand, that the spheroidal echinoids, in reality, depart further from the general plan and from the embryonic form than the elongated spatangoids do; and that the peculiar dental apparatus and the pedicellariae of the former are marks of at least as great differentiation as the petaloid ambulacra and semitae of the latter. once more, the prevalence of macrurous before brachyurous podophthalmia is, apparently, a fair piece of evidence in favour of progressive modification in the same order of crustacea; and yet the case will not stand much sifting, seeing that the macrurous podophthalmia depart as far in one direction from the common type of podophthalmia, or from any embryonic condition of the brachyura, as the brachyura do in the other; and that the middle terms between macrura and brachyura--the anomura--are little better represented in the older mesozoic rocks than the brachyura are. none of the cases of progressive modification which are cited from among the invertebrata appear to me to have a foundation less open to criticism than these; and if this be so, no careful reasoner would, i think, be inclined to lay very great stress upon them. among the vertebrata, however, there are a few examples which appear to be far less open to objection. it is, in fact, true of several groups of vertebrata which have lived through a considerable range of time, that the endoskeleton (more particularly the spinal column) of the older genera presents a less ossified, and, so far, less differentiated, condition than that of the younger genera. thus the devonian ganoids, though almost all members of the same sub-order as 'polypterus', and presenting numerous important resemblances to the existing genus, which possesses biconcave vertebrae, are, for the most part, wholly devoid of ossified vertebral centra. the mesozoic lepidosteidae, again, have, at most, biconcave vertebrae, while the existing 'lepidosteus' has salamandroid, opisthocoelous, vertebrae. so, none of the paleozoic sharks have shown themselves to be possessed of ossified vertebrae, while the majority of modern sharks possess such vertebrae. again, the more ancient crocodilia and lacertilia have vertebrae with the articular facets of their centra flattened or biconcave, while the modern members of the same group have them procoelous. but the most remarkable examples of progressive modification of the vertebral column, in correspondence with geological age, are those afforded by the pycnodonts among fish, and the labyrinthodonts among amphibia. the late able ichthyologist heckel pointed out the fact, that, while the pycnodonts never possess true vertebral centra, they differ in the degree of expansion and extension of the ends of the bony arches of the vertebrae upon the sheath of the notochord; the carboniferous forms exhibiting hardly any such expansion, while the mesozoic genera present a greater and greater development, until, in the tertiary forms, the expanded ends become suturally united so as to form a sort of false vertebra. hermann von meyer, again, to whose luminous researches we are indebted for our present large knowledge of the organization of the older labyrinthodonts, has proved that the carboniferous 'archegosaurus' had very imperfectly developed vertebral centra, while the triassic 'mastodonsaurus' had the same parts completely ossified. [ ] the regularity and evenness of the dentition of the 'anoplotherium', as contrasted with that of existing artiodactyles, and the assumed nearer approach of the dentition of certain ancient carnivores to the typical arrangement, have also been cited as exemplifications of a law of progressive development, but i know of no other cases based on positive evidence which are worthy of particular notice. what, then, does an impartial survey of the positively ascertained truths of paleontology testify in relation to the common doctrines of progressive modification, which suppose that modification to have taken place by a necessary progress from more to less embryonic forms, or from more to less generalized types, within the limits of the period represented by the fossiliferous rocks? it negatives those doctrines; for it either shows us no evidence of any such modification, or demonstrates it to have been very slight; and as to the nature of that modification, it yields no evidence whatsoever that the earlier members of any long-continued group were more generalized in structure than the later ones. to a certain extent, indeed, it may be said that imperfect ossification of the vertebral column is an embryonic character; but, on the other hand, it would be extremely incorrect to suppose that the vertebral columns of the older vertebrata are in any sense embryonic in their whole structure. obviously, if the earliest fossiliferous rocks now known are coeval with the commencement of life, and if their contents give us any just conception of the nature and the extent of the earliest fauna and flora, the insignificant amount of modification which can be demonstrated to have taken place in any one group of animals, or plants, is quite incompatible with the hypothesis that all living forms are the results of a necessary process of progressive development, entirely comprised within the time represented by the fossiliferous rocks. contrariwise, any admissible hypothesis of progressive modification must be compatible with persistence without progression, through indefinite periods. and should such an hypothesis eventually be proved to be true, in the only way in which it can be demonstrated, viz. by observation and experiment upon the existing forms of life, the conclusion will inevitably present itself, that the paleozoic, mesozoic, and cainozoic faunae and florae, taken together, bear somewhat the same proportion to the whole series of living beings which have occupied this globe, as the existing fauna and flora do to them. such are the results of paleontology as they appear, and have for some years appeared, to the mind of an inquirer who regards that study simply as one of the applications of the great biological sciences, and who desires to see it placed upon the same sound basis as other branches of physical inquiry. if the arguments which have been brought forward are valid, probably no one, in view of the present state of opinion, will be inclined to think the time wasted which has been spent upon their elaboration. [footnote : the anniversary address to the geological society for .] [footnote : "le plus grand service qu'on puisse rendre a la science est d'y faire place nette avant d'y rien construire."--cuvier] [footnote : anniversary address for , 'quart. journ. geol. soc.' vol. vii.] [footnote : see hooker's 'introductory essay to the flora of tasmania', p. xxiii.] [footnote : see the abstract of a lecture "on the persistent types of animal life," in the 'notices of the meetings of the royal institution of great britain'.--june , , vol. iii. p. . [footnote : "memoirs of the geological survey of the united kingdom.--decade x. preliminary essay upon the systematic arrangement of the fishes of the devonian epoch."] [footnote : as the address is passing through the press (march , ), evidence lies before me of the existence of a new labyrinthodont ('pholidogaster'), from the edinburgh coal-field, with well-ossified vertebral centra.] none theory of the earth, volume i with proofs and illustrations, in four parts by james hutton, m.d. & f.r.s.e. . contents. part i. theory of the earth; with the examination of different opinions on that subject. chap. i. theory of the earth; or an investigation of the laws observable in the composition, dissolution, and restoration of land upon the globe. sect. i.--prospect of the subject to be treated of. sect. ii.--an investigation of the natural operations employed in consolidating the strata of the globe. sect. iii.--investigation of the natural operations employed in the production of land above the surface of the sea. sect. iv.--system of decay and renovation observed in the earth. chap. ii. an examination of mr kirwan's objections to the igneous origin of stony substances. chap. iii. of physical systems, and geological theories, in general. chap. iv. the supposition of primitive mountains refuted. chap. v. concerning that which may be termed the primary part of the present earth. chap. vi. the theory of interchanging sea and land, illustrated by an investigation of the primary and secondary strata . sect. i.--a distinct view of the primary and secondary strata. sect. ii.--the theory confirmed from observations made on purpose to elucidate the subject. chap. vii. opinions examined with regard to petrifaction, or mineral concretion. chap. viii. the nature of mineral coal, and the formation of bituminous strata, investigated. sect. i.--purpose of this inquiry. sect. ii.--natural history of coal strata, and theory of this geological operation. sect. iii.--the mineralogical operations of the earth illustrated from the theory of fossil coal. part i. theory of the earth; with the examination of different opinions on that subject. in eight chapters. chapter i. theory of the earth; or an investigation of the laws observable in the composition, dissolution, and restoration, of land upon the globe. section i. prospect of the subject to be treated of. when we trace the parts of which this terrestrial system is composed, and when we view the general connection of those several parts, the whole presents a machine of a peculiar construction by which it is adapted to a certain end. we perceive a fabric, erected in wisdom, to obtain a purpose worthy of the power that is apparent in the production of it. we know little of the earth's internal parts, or of the materials which compose it at any considerable depth below the surface. but upon the surface of this globe, the more inert matter is replenished with plants, and with animal and intellectual beings. where so many living creatures are to ply their respective powers, in pursuing the end for which they were intended, we are not to look for nature in a quiescent state; matter itself must be in motion, and the scenes of life a continued or repeated series of agitations and events. this globe of the earth is a habitable world; and on its fitness for this purpose, our sense of wisdom in its formation must depend. to judge of this point, we must keep in view, not only the end, but the means also by which that end is obtained. these are, the form of the whole, the materials of which it is composed, and the several powers which concur, counteract, or balance one another, in procuring the general result. the form and constitution of the mass are not more evidently calculated for the purpose of this earth as a habitable world, than are the various substances of which that complicated body is composed. soft and hard parts variously combine to form a medium consistence, adapted to the use of plants and animals; wet and dry are properly mixed for nutrition, or the support of those growing bodies; and hot and cold produce a temperature or climate no less required than a soil: insomuch, that there is not any particular, respecting either the qualities of the materials, or the construction of the machine, more obvious to our perception, than are the presence and efficacy of design and intelligence in the power that conducts the work. in taking this view of things, where ends and means are made the object of attention, we may hope to find a principle upon which the comparative importance of parts in the system of nature may be estimated, and also a rule for selecting the object of our inquiries. under this direction, science may find a fit subject of investigation in every particular, whether of _form_, _quality_, or _active power_, that presents itself in this system of motion and of life; and which, without a proper attention to this character of the system, might appear anomalous and incomprehensible. it is not only by seeing those general operations of the globe which depend upon its peculiar construction as a machine, but also by perceiving how far the particulars, in the construction of that machine, depend upon the general operations of the globe, that we are enabled to understand the constitution of this earth as a thing formed by design. we shall thus also be led to acknowledge an order, not unworthy of divine wisdom, in a subject which, in another view, has appeared as the work of chance, or as absolute disorder and confusion. to acquire a general or comprehensive view of this mechanism of the globe, by which it is adapted to the purpose of being a habitable world, it is necessary to distinguish three different bodies which compose the whole. these are, a solid body of earth, an aqueous body of sea, and an elastic fluid of air. it is the proper shape and disposition of these three bodies that form this globe into a habitable world; and it is the manner in which these constituent bodies are adjusted to each other, and the laws of action by which they are maintained in their proper qualities and respective departments, that form the theory of the machine which we are now to examine. let us begin with some general sketch of the particulars now mentioned. _ st_, there is a central body in the globe. this body supports those parts which come to be more immediately exposed to our view, or which may be examined by our sense and observation. this first part is commonly supposed to be solid and inert; but such a conclusion is only mere conjecture; and we shall afterwards find occasion, perhaps, to form another judgment in relation to this subject, after we have examined strictly, upon scientific principles, what appears upon the surface, and have formed conclusions concerning that which must have been transacted in some more central part. _ dly_, we find a fluid body of water. this, by gravitation, is reduced to a spherical form, and by the centrifugal force of the earth's rotation, is become oblate. the purpose of this fluid body is essential in the constitution of the world; for, besides affording the means of life and motion to a multifarious race of animals, it is the source of growth and circulation to the organized bodies of this earth, in being the receptacle of the rivers, and the fountain of our vapours. _ dly_, we have an irregular body of land raised above the level of the ocean. this, no doubt, is the smallest portion of the globe; but it is the part to us by far most interesting. it is upon the surface of this part that plants are made to grow; consequently, it is by virtue of this land that animal life, as well as vegetation, is sustained in this world. _lastly_, we have a surrounding body of atmosphere, which completes the globe. this vital fluid is no less necessary, in the constitution of the world, than are the other parts; for there is hardly an operation upon the surface of the earth, that is not conducted or promoted by its means. it is a necessary condition for the sustenance of fire; it is the breath of life to animals; it is at least an instrument in vegetation; and, while it contributes to give fertility and health to things that grow, it is employed in preventing noxious effects from such as go into corruption. in short, it is the proper means of circulation for the matter of this world, by raising up the water of the ocean, and pouring it forth upon the surface of the earth. such is the mechanism of the globe: let us now mention some of those powers by which motion is produced, and activity procured to the mere machine. first, there is the progressive force, or moving power, by which this planetary body, if solely actuated, would depart continually from the path which it now pursues, and thus be for ever removed from its end, whether as a planetary body, or as a globe sustaining plants and animals, which may be termed a living world. but this moving body is also actuated by gravitation, which inclines it directly to the central body of the sun. thus it is made to revolve about that luminary, and to preserve its path. it is also upon the same principles, that each particular part upon the surface of this globe, is alternately exposed to the influence of light and darkness, in the diurnal rotation of the earth, as well as in its annual revolution. in this manner are produced the vicissitudes of night and day, so variable in the different latitudes from the equator to the pole, and so beautifully calculated to equalise the benefits of light, so variously distributed in the different regions of the globe. gravitation, and the _vis infita_ of matter, thus form the first two powers distinguishable in the operations of our system, and wisely adapted to the purpose for which they are employed. we next observe the influence of light and heat, of cold and condensation. it is by means of these two powers that the various operations of this living world are more immediately transacted; although the other powers are no less required, in order to produce or modify these great agents in the economy of life, and system of our changing things. we do not now inquire into the nature of those powers, or investigate the laws of light and heat, of cold and condemnation, by which the various purposes of this world are accomplished; we are only to mention those effects which are made sensible to the common understanding of mankind, and which necessarily imply a power that is employed. thus, it is by the operation of those powers that the varieties of season in spring and autumn are obtained, that we are blessed with the vicissitudes of summer's heat and winter's cold, and that we possess the benefit of artificial light and culinary fire. we are thus bountifully provided with the necessaries of life; we are supplied with things conducive to the growth and preservation of our animal nature, and with fit subjects to employ and to nourish our intellectual powers. there are other actuating powers employed in the operations of this globe, which we are little more than able to enumerate; such are those of electricity, magnetism, and subterraneous heat or mineral fire. powers of such magnitude or force, are not to be supposed useless in a machine contrived surely not without wisdom; but they are mentioned here chiefly on account of their general effect; and it is sufficient to have named powers, of which the actual existence is well known, but of which the proper use in the constitution of the world is still obscure. the laws of electricity and magnetism have been well examined by philosophers; but the purposes of those powers in the economy of the globe have not been discovered. subterraneous fire, again, although the most conspicuous in the operations of this world, and often examined by philosophers, is a power which has been still less understood, whether with regard to its efficient or final cause. it has hitherto appeared more like the accident of natural things, than the inherent property of the mineral region. it is in this last light, however, that i wish to exhibit it, as a great power acting a material part in the operations of the globe, and as an essential part in the constitution of this world. we have thus surveyed the machine in general, with those moving powers, by which its operations, diversified almost _ad infinitum_, are performed. let us now confine our view, more particularly, to that part of the machine on which we dwell, that so we may consider the natural consequences of those operations which, being within our view, we are better qualified to examine. this subject is important to the human race, to the possessor of this world, to the intelligent being man, who foresees events to come, and who, in contemplating his future interest, is led to inquire concerning causes, in order that he may judge of events which otherwise he could not know. if, in pursuing this object, we employ our skill in research, not in forming vain conjectures; and if _data_ are to be found, on which science may form just conclusions, we should not long remain in ignorance with respect to the natural history of this earth, a subject on which hitherto opinion only, and not evidence, has decided: for in no subject, perhaps, is there naturally less defect of evidence, although philosophers, led by prejudice, or misguided by false theory, may have neglected to employ that light by which they should have seen the system of this world. but to proceed in pursuing a little farther our general or preparatory ideas. a solid body of land could not have answered the purpose of a habitable world; for, a soil is necessary to the growth of plants; and a soil is nothing but the materials collected from the destruction of the solid land. therefore, the surface of this land, inhabited by man, and covered with plants and animals, is made by nature to decay, in dissolving from that hard and, compact state in which it is found below the soil; and this soil is necessarily washed away, by the continual circulation of the water, running from the summits of the mountains towards the general receptacle of that fluid. the heights of our land are thus levelled with the shores; our fertile plains are formed from the ruins of the mountains; and those travelling materials are still pursued by the moving water, and propelled along the inclined surface of the earth[ ] these moveable materials, delivered into the sea, cannot, for a long continuance, rest upon the shore; for, by the agitation of the winds, the tides and currents, every moveable thing is carried farther and farther along the shelving bottom of the sea, towards the unfathomable regions of the ocean. [note : m. de luc, in his second letter to me, published in the monthly review for , says, "you ought to have proved that both gravel and sand are carried from our continents to the sea; which, on the contrary, i shall prove not to be the case." he then endeavours to prove his assertion, by observing, that, in certain places where there is not either sufficient declivity in the surface, or force in the running water, gravel and sand are made to rest, and do not travel to the sea. this surely is a fact to which i most readily assent; but, on the other hand, i hope he will acknowledge, that, where there is sufficient declivity in the surface, or force in the running water, sand, gravel, and stones, are travelled upon the land, and are thus carried into the sea--at last. this is all that my theory requires, and this is what i believe will be admitted, without any farther proof on my part.] if the vegetable soil is thus constantly removed from the surface of the land, and if its place is thus to be supplied from the dissolution of the solid earth, as here represented, we may perceive an end to this beautiful machine; an end, arising from no error in its constitution as a world, but from that destructibility of its land which is so necessary in the system of the globe, in the economy of life and vegetation. the immense time necessarily required for this total destruction of the land, must not be opposed to that view of future events, which is indicated by the surest facts, and most approved principles. time, which measures every thing in our idea, and is often deficient to our schemes, is to nature endless and as nothing; it cannot limit that by which alone it had existence; and, as the natural course of time, which to us seems infinite, cannot be bounded by any operation that may have an end, the progress of things upon this globe, that is, the course of nature, cannot be limited by time, which must proceed in a continual succession. we are, therefore, to consider as inevitable the deduction of our land, so far as effected by those operations which are necessary in the purpose of the globe, considered as a habitable world; and, so far as we have not examined any other part of the economy of nature, in which other operations and a different intention might appear. we have now considered the globe of this earth as a machine, constructed upon chemical as well as mechanical principles, by which its different parts are all adapted, in form, in quality, and in quantity, to a certain end; an end attained with certainty or success; and an end from which we may perceive wisdom, in contemplating the means employed. but is this world to be considered thus merely as a machine, to last no longer than its parts retain their present position, their proper forms and qualities? or may it not be also considered as an organized body? such as has a constitution in which the necessary decay of the machine is naturally repaired, in the exertion of those productive powers by which it had been formed. this is the view in which we are now to examine the globe; to see if there be, in the constitution of this world, a reproductive operation, by which a ruined constitution may be again repaired, and a duration or stability thus procured to the machine, considered as a world sustaining plants and animals. if no such reproductive power, or reforming operation, after due inquiry, is to be found in the constitution of this world, we should have reason to conclude, that the system of this earth has either been intentionally made imperfect, or has not been the work of infinite power and wisdom. here is an important question, therefore, with regard to the constitution of this globe; a question which, perhaps, it is in the power of man's sagacity to resolve; and a question which, if satisfactorily resolved, might add some lustre to science and the human intellect. animated with this great, this interesting view, let us strictly examine our principles, in order to avoid fallacy in our reasoning; and let us endeavour to support our attention, in developing a subject that is vast in its extent, as well as intricate in the relation of parts to be stated. the globe of this earth is evidently made for man. he alone, of all the beings which have life upon this body, enjoys the whole and every part; he alone is capable of knowing the nature of this world, which he thus possesses in virtue of his proper right; and he alone can make the knowledge of this system a source of pleasure, and the means of happiness. man alone, of all the animated beings which enjoy the benefits of this earth, employs the knowledge which he there receives, in leading him to judge of the intention of things, as well as of the means by which they are brought about; and he alone is thus made to enjoy, in contemplation as well as sensual pleasure, all the good that may be observed in the constitution of this world; he, therefore, should be made the first subject of inquiry. now, if we are to take the written history of man for the rule by which we should judge of the time when the species first began, that period would be but little removed from the present state of things. the mosaic history places this beginning of man at no great distance; and there has not been found, in natural history, any document by which a high antiquity might be attributed to the human race. but this is not the case with regard to the inferior species of animals, particularly those which inhabit the ocean and its shores. we find, in natural history, monuments which prove that those animals had long existed; and we thus procure a measure for the computation of a period of time extremely remote, though far from being precisely ascertained. in examining things present, we have data from which to reason with regard to what has been; and, from what has actually been, we have data for concluding with regard to that which is to happen hereafter. therefore, upon the supposition that the operations of nature are equable and steady, we find, in natural appearances, means for concluding a certain portion of time to have necessarily elapsed, in the production of those events of which we see the effects. it is thus that, in finding the relics of sea-animals of every kind in the solid body of our earth, a natural history of those animals is formed, which includes a certain portion of time; and, for the ascertaining this portion of time, we must again have recourse to the regular operations of this world. we shall thus arrive at facts which indicate a period to which no other species of chronology is able to remount. in what follows, therefore, we are to examine the construction of the present earth, in order to understand the natural operations of time past; to acquire principles, by which we may conclude with regard to the future course of things, or judge of those operations, by which a world, so wisely ordered, goes into decay; and to learn, by what means such a decayed world may be renovated, or the waste of habitable land upon the globe repaired. this, therefore, is the object which we are to have in view during this physical investigation; this is the end to which are to be directed all the steps in our cosmological pursuit. the solid parts of the globe are, in general, composed of sand, of gravel, of argillaceous and calcareous strata, or of the various compositions of these with some other substances, which it is not necessary now to mention. sand is separated and sized by streams and currents; gravel is formed by the mutual attrition of stones agitated in water; and marly, or argillaceous strata, have been collected, by subsiding in water with which those earthy substances had been floated. thus, so far as the earth is formed of these materials, that solid body would appear to have been the production of water, winds, and tides. but that which renders the original of our land clear and evident, is the immense quantities of calcareous bodies which had belonged to animals, and the intimate connection of these masses of animal production with the other strata of the land. for it is to be proved, that all these calcareous bodies, from the collection of which the strata were formed, have belonged to the sea, and were produced in it. we find the marks of marine animals in the most solid parts of the earth; consequently, those solid parts have been formed after the ocean was inhabited by those animals which are proper to that fluid medium. if, therefore, we knew the natural history of those solid parts, and could trace the operations of the globe, by which they had been formed, we would have some means for computing the time through which those species of animals have continued to live. but how shall we describe a process which nobody has seen performed, and of which no written history gives any account? this is only to be investigated, _first_, in examining the nature of those solid bodies, the history of which we want to know; and, _dly_, in examining the natural operations of the globe, in order to see if there now actually exist such operations, as, from the nature of the solid bodies, appear to have been necessary to their formation. but, before entering more particularly into those points of discussion, by which the question is to be resolved, let us take a general view of the subject, in order to see what it is which science and observation must decide. in all the regions of the globe, immense masses are found, which, though at present in the most solid state, appear to have been formed by the collection of the calcareous _exuviae_ of marine animals. the question at present is not, in what manner those collections of calcareous relics have become a perfect solid body, and have been changed from an animal to a mineral substance; for this is a subject that will be afterwards considered; we are now only inquiring, if such is truly the origin of those mineral masses. that all the masses of marble or limestone are composed of the calcareous matter of marine bodies, may be concluded from the following facts: _st_, there are few beds of marble or limestone, in which may not be found some of those objects which indicate the marine origin of the mass. if, for example, in a mass of marble, taken from a quarry upon the top of the alps or andes[ ], there shall be found one cockle-shell, or piece of coral, it must be concluded, that this bed of stone had been originally formed at the bottom of the sea, as much as another bed which is evidently composed almost altogether of cockle-shells and coral. if one bed of limestone is thus found to have been of a marine origin, every concomitant bed of the same kind must be also concluded to have been formed in the same manner. [note : "cette sommité élevée de toises au dessus de notre lac, et par conséquent de au dessus de la mer, est remarquable en ce que l'on y voit des fragmens d'huîtres pétrifiés.--cette montagne est dominée par un rocher escarpé, qui s'il n'est pas inaccessible, est du moins d'un bien difficile accès; il paroît presqu'entièrement composé de coquillages pétrifiés, renfermés dans un roc calcaire, ou marbre grossier noirâtre. les fragmens qui s'en détachent, et que l'on rencontre en montant à la croix de fer, sont remplis de _turbinites_ de différentes espèces." m. de saussure, _voyage dans les alpes_, p. .] we thus shall find the greatest part of the calcareous masses upon this globe to have originated from marine calcareous bodies; for whether we examine marbles, limestones, or such solid masses as are perfectly changed from the state of earth, and are become compact and hard, or whether we examine the soft, earthy, chalky or marly strata, of which so much of this earth is composed, we still find evident proofs, that those beds had their origin from materials deposited at the bottom of the sea; and that they have the calcareous substance which they contain, from the same source as the marbles or the limestones. _dly_, in those calcareous strata, which are evidently of marine origin, there are many parts that are of a sparry structure, that is to say, the original texture of those beds, in such places, has been dissolved, and a new structure has been assumed, which is peculiar to a certain state of the calcareous earth. this change is produced by crystallisation, in consequence of a previous state of fluidity, which has so disposed the concreting parts, as to allow them to assume a regular shape and structure proper to that substance. a body, whose external form has been modified by this process, is called a _crystal_; one whose internal arrangement of parts is determined by it, is said to be of a _sparry structure_; and this is known from its fracture. _dly_, there are, in all the regions of the earth, huge masses of calcareous matter, in that crystalline form of sparry state, in which perhaps no vestige can be found of any organised body, nor any indication that such calcareous matter had belonged to animals; but as, in other masses, this sparry structure, or crystalline state, is evidently assumed by the marine calcareous substances, in operations which are natural to the globe, and which are necessary to the consolidation of the strata, it does not appear, that the sparry masses, in which no figured body is formed, have been originally different from other masses, which, being only crystallised in part, and in part still retaining their original form, leave ample evidence of their marine origin[ ]. [note : m. de saussure, describing the marble of aigle, says, "les tables polies de ce marbre présentent fréquemment des coquillages, dont la plupart sont des peignes striés, et de très-beaux madrépores. tous ces corps marins on pris entierement la nature et le grain même du marbre, on n'y voit presque jamais la coquille sous sa forme originaire."] we are led, in this manner, to conclude, that all the strata of the earth, not only those consisting of such calcareous masses, but others superincumbent upon these, have had their origin at the bottom of the sea, by the collection of sand and gravel, of shells, of coralline and crustaceous bodies, and of earths and clays, variously mixed, or separated and accumulated. here is a general conclusion, well authenticated in the appearances of nature, and highly important in the natural history of the earth. the general amount of our reasoning is this, that nine-tenths, perhaps, or ninety-nine hundredths of this earth, so far as we see, have been formed by natural operations of the globe, in collecting loose materials, and depositing them at the bottom of the sea; consolidating those collections in various degrees, and either elevating those consolidated masses above the level on which they were formed, or lowering the level of that sea. there is a part of the solid earth which we may at present neglect, not as being persuaded that this part may not also be found to come under the general rule of formation with the rest, but as considering this part to be of no consequence in forming a general rule, which shall comprehend almost the whole, without doing it absolutely. this excluded part consists of certain mountains and masses of granite. these are thought to be still older in their formation, and are said never to be found superincumbent on strata which must be acknowledged as the productions of the sea. having thus found the greater part, if not the whole, of the solid land to have been originally composed at the bottom of the sea, we may now, in order to form a proper idea of these operations, suppose the whole of this seaborn land to be again dispersed along the bottom of the ocean, the surface of which would rise proportionally over the globe. we would thus have a spheroid of water, with granite rocks and islands scattered here and there. but this would not be the world which we inhabit; therefore, the question now is, how such continents, as we actually have upon the globe, could be erected above the level of the sea. it must be evident, that no motion of the sea, caused by this earth revolving in the solar system, could bring about that end; for let us suppose the axis of the earth to be changed from the present poles, and placed in the equinoctial line, the consequence of this might, indeed, be the formation of a continent of land about each new pole, from whence the sea would run towards the new equator; but all the rest of the globe would remain an ocean. some new points might be discovered, and others, which before appeared above the surface of the sea, would be sunk by the rising of the water; but, on the whole, land could only be gained substantially at the poles. such a supposition, as this, if applied to the present state of things, would be destitute of every support, as being incapable of explaining what appears. but even allowing that, by the changed axis of the earth, or any other operation of the globe, as a planetary body revolving in the solar system, great continents of land could have been erected from the place of their formation, the bottom of the sea, and placed in a higher elevation, compared with the surface of that water, yet such a continent as this could not have continued stationary for many thousand years; nor could a continent of this kind have presented to us, every where within its body, masses of consolidated marble, and other mineral substances, in a state as different as possible from that in which they were, when originally collected together in the sea. consequently, besides an operation, by which the earth at the bottom of the sea should be converted into an elevated land, or placed high above the level of the ocean, there is required, in the operations of the globe, a consolidating power, by which the loose materials that had subsided from water, should be formed into masses of the most perfect solidity, having neither water nor vacuity between their various constituent parts, nor in the pores of those constituent parts themselves. here is an operation of the globe, whether chemical or mechanical, which is necessarily connected with the formation of our present continents: therefore, had we a proper understanding of this secret operation, we might thereby be enabled to form an opinion, with regard to the nature of that unknown power, by which the continents have been placed above the surface of that water wherein they had their birth. if this consolidating operation be performed at the bottom of the ocean, or under great depths of the earth, of which our continents are composed, we cannot be witnesses to this mineral process, or acquire the knowledge of natural causes, by immediately observing the changes which they produce; but though we have not this immediate observation of those changes of bodies, we have, in science, the means of reasoning from distant events; consequently, of discovering, in the general powers of nature, causes for those events of which we see the effects. that the consolidating operation, in general, lies out of the reach of our immediate observation, will appear from the following truth: all the consolidated masses, of which we now inquire into the cause, are, upon the surface of the earth, in a state of general decay, although the various natures of those bodies admit of that dissolution in very different degrees[ ] from every view of the subject, therefore, we are directed to look into those consolidated masses themselves, in order to find principles from whence to judge of those operations by which they had attained their hardness or consolidated state. it must be evident, that nothing but the most general acquaintance with the laws of acting substances, and with those of bodies changing by the powers of nature, can enable us to set about this undertaking with any reasonable prospect of success; and here the science of chemistry must be brought particularly to our aid; for this science, having for its object the changes produced upon the sensible qualities, as they are called, of bodies, by its means we may be enabled to judge of that which is possible according to the laws of nature, and of that which, in like manner, we must consider as impossible. [note : stalactical and certain ferruginous concretions may seem to form an exception to the generality of this proposition. but an objection of this kind could only arise from a partial view of things; for the concretion here is only temporary; it is in consequence of a solution, and it is to be followed by a dissolution, which will be treated of in its proper place.] whatever conclusions, therefore, by means of this science, shall be attained, in just reasoning from natural appearances, this must be held as evidence, where more immediate proof cannot be obtained; and, in a physical subject, where things actual are concerned, and not the imaginations of the human mind, this proof will be considered as amounting to a demonstration. section ii. an investigation of the natural operations employed in consolidating the strata of the globe. we are now about to investigate those mineral operations of the globe by which the qualities of hardness and solidity, consequently of strength and durability, are procured to great bodies of this earth. that those qualities are not original to such bodies, but actually superinduced in the natural operations of the earth, will appear from the examination of some of the hardest and most solid of those mineral bodies. in such masses, (for example of flint and agate,) we find included shells and coralline bodies. consequently, there must be a natural operation in the globe for consolidating and hardening its soft and loose materials. it is concerning the nature of this consolidating operation that we are now to inquire. there are just two ways in which porous or spongy bodies can be consolidated, and by which substances may be formed into masses of a natural shape and regular structure; the one of these is simple _congelation_ from a fluid state, by means of cold; the other is _accretion_; and this includes a separatory operation, as well as that by which the solid body is to be produced. but in whichever of these ways solidity shall be procured, it must be brought about by first inducing fluidity, either immediately by the action of heat, or mediately with the assistance of a solvent, that is, by the operation of solution. therefore, fire and water may be considered as the general agents in this operation, which we would explore. heat has been already mentioned as a general power, and as acting in all the different parts of the globe; i would now wish more particularly to call the attention of the reader to subterraneous fire, or heat, as a powerful agent in the mineral regions, and as a cause necessarily belonging to the internal constitution of this earth. it is not our purpose at present to inquire into the particular nature of this power of subterraneous heat, or to trace the proper connection and analogy of the internal fire with that which is so necessary to our life, and which acts so great a part upon the surface of the earth, this being reserved for the last part. our intention in here mentioning it, is only to dispose the mind to look for active powers or efficient causes, in that part of the earth which has been commonly considered as passive and inert, but which will be found extremely active, and the source of mighty revolutions in the fate of land. there may, indeed, be some difficulty in conceiving all the modifications of this mineral power; but as, on the one hand, we are not arbitrarily to assume an agent, for the purpose of explaining events, or certain appearances which are not understood; so, on the other, we must not refuse to admit the action of a known power, when this is properly suggested in the appearances of things; and, though we may not understand all the modifications, or the whole capacity and regulation of this power in bodies, we are not to neglect the appropriating to it, as a cause, those effects which are natural to it, and which, so far as we know, cannot belong to any other. on all occasions, we are to judge from what we know; and, we are only to avoid concluding from our suppositions, in cases where evidence or real information is necessarily required. the subject now considered, subterraneous fire, will afford an example of that truth; and, a general view of this great natural power will here find a proper place, before the application of it for the explanation of natural appearances. no event is more the object of our notice, or more interesting as a subject for our study, than is the burning of a fire: but, the more that philosophers have studied this subject, the more they seem to differ as to the manner in which that conspicuous event is to be explained. therefore, being so ignorant with regard to that fire of which we see the origin as well as the more immediate effects, how cautious should we be in judging the nature of subterraneous fire from the burning of bodies, a subject which we so little understand. but, though the cause of fire in general, or the operations of that power in its extreme degrees, be for us a subject involved in much obscurity, this is not the case with regard to the more common effects of heat; and, tho' the actual existence of subterraneous fire, as the cause of light and heat, might be a thing altogether problematical in our opinion; yet, as to other effects, there are some of these from which the action of that liquefying power may be certainly concluded as having taken place within the mineral region, although the cause should be in every other respect a thing to us unknown. in that case, where the operation or effect is evident, and cannot be disputed, to refuse to admit the power in question, merely because we had not seen it act, or because we know not every rule which it may observe in acting, would be only to found an argument upon our ignorance; it would be to misunderstand the nature of investigating physical truths, which must proceed by reasoning from effect to cause. our knowledge is extremely limited with regard to the effects of heat in bodies, while acting under different conditions, and in various degrees. but though our knowledge in these respects is limited, our judgment with regard to the efficacy of this power of heat is in its nature positive, and contains not any thing that is doubtful or uncertain. all mankind, who have the opportunity, know that the hard substance of ice is by heat converted into water, wherein no hardness remains; and the profound philosophy of dr black, in relation to the subject of _latent heat_, as that of sir isaac newton, in relation to the weight of bodies, is not necessary to convince the world that in the one case ice will melt, and in the other, that heavy bodies will move when unsupported. but though, in the abstract doctrine of _latent heat_, the ingenuity of man has discovered a certain measure for the quantity of those commutable effects which are perceived; and though this be a progress of science far above the apprehension of the vulgar, yet still, that solid bodies are changed into fluids, by the power of heat, is the same unalterable judgment, which the savage forms as well as the philosopher. here, therefore, are evident effects, which mankind in general attribute to the power of heat; and it is from those known effects that we are to investigate subterraneous fire, or to generalise the power of heat, as acting in the interior parts, as well as on the surface of this earth. if, indeed, there were any other cause for fluidity besides the operation of fire or the power of heat, in that case the most evident proof, with regard to the flowing, or former fluidity, of mineral bodies, would draw to no conclusion in proving the existence of mineral fire; but when we have not the smallest reason for conjecturing any other cause, or the least doubt with regard to that which, in the doctrine of latent heat, has been properly investigated, the proofs which we shall bring, of fusion in all the minerals of this earth, must be held as proofs of mineral fire, in like manner as the proof of subterraneous fire would necessarily imply mineral fusion as its natural effect. thus we have, in our physical investigation, several points in view. first, from the present state of things, to infer a former state of fusion among mineral bodies. secondly, from that former fusion, to infer the actual existence of mineral fire in the system of the earth. and, lastly, from the acknowledged fact of subterraneous fire as a cause, to reason with regard to the effects of that power in mineral bodies. but besides the power or effect of subterraneous heat in bodies which are unorganised, and without system, in the construction of their different parts, we have to investigate the proper purpose of this great agent in the system of this world, which may be considered as a species of organised body. here, therefore, final causes are to be brought into view, as well as those which are efficient. now, in a subject involved with so much obscurity, as must be for us the internal regions of the globe, the consideration of efficient and final causes may contribute mutually to each others evidence, when separately the investigation of either might be thought unsatisfactory or insufficient. so far it seemed necessary to premise with regard to the great mineral power which we are to employ as an agent in the system of this earth; and it may be now observed, that it is in the proper relation of this power of heat and the fluidity or softness of bodies, as cause and effect, that we are to find a physical principle or argument for detecting those false theories of the earth that have been only imagined, and not properly founded on fact or observation. it is also by means of this principle, that we shall be enabled to form a true theory of the mineral region, in generalising particular effects to a common cause. let us now proceed in endeavouring to decide this important question, viz. by what active principle is it, that the present state of things, which we observe in the strata of the earth, a state so very different from that in which those bodies had been formed originally, has been brought about? two causes have been now proposed for the consolidating of loose materials which had been in an incoherent state; these are, on the one hand, fire; or, on the other, water, as the means of bringing about that event. we are, therefore, to consider well, what may be the consequences of consolidation by the one or other of those agents; and what may be the respective powers of those agents with respect to this operation. if we are not informed in this branch of science, we may gaze without instruction upon the most convincing proofs of what we want to attain. if our knowledge is imperfect, we may form erroneous principles, and deceive ourselves in reasoning with regard to those works of nature, which are wisely calculated for our instruction. the strata, formed at the bottom of the sea, are to be considered as having been consolidated, either by aqueous solution and crystallization, or by the effect of heat and fusion. if it is in the first of these two ways that the solid strata of the globe have attained to their present state, there will be a certain uniformity observable in the effects; and there will be general laws, by which this operation must have been conducted. therefore, knowing those general laws, and making just observations with regard to the natural appearances of those consolidated masses, a philosopher, in his closet, should be able to determine, what may, and what may not have been transacted in the bowels of the earth, or below the bottom of the ocean. let us now endeavour to ascertain what may have been the power of water, acting under fixed circumstances, operating upon known substances, and conducting to a certain end. the action of water upon all different substances is an operation with which we are familiar. we have it in our power to apply water in different degrees of heat for the solution of bodies, and under various degrees of compression; consequently, there is no reason to conclude any thing mysterious in the operations of the globe, which are to be performed by means of water, unless an immense compressing power should alter the nature of those operations. but compression alters the relation of evaporation only with regard to heat, or it changes the degree of heat which water may be made to sustain; consequently, we are to look for no occult quality in water acting upon bodies at the bottom of the deepest ocean, more than what can be observed in experiments which we have it in our power to try. with regard again to the effect of time: though the continuance of time may do much in those operations which are extremely slow, where no change, to our observation, had appeared to take place, yet, where it is not in the nature of things to produce the change in question, the unlimited course of time would be no more effectual, than the moment by which we measure events in our observations. water being the general medium in which bodies collected at the bottom of the sea are always contained, if those masses of collected matter are to be consolidated by solution, it must be by the dissolution of those bodies in that water as a menstruum, and by the concretion or crystallization of this dissolved matter, that the spaces, first occupied by water in those masses, are afterwards to be filled with a hard and solid substance; but without some other power, by which the water contained in those cavities and endless labyrinths of the strata, should be separated in proportion as it had performed its task, it is inconceivable how those masses, however changed from the state of their first subsidence, should be absolutely consolidated, without any visible or fluid water in their composition. besides this difficulty of having the water separated from the porous masses which are to be consolidated, there is another with which, upon this supposition, we have to struggle. this is, from whence should come the matter with which the numberless cavities in those masses are to be filled? the water in the cavities and interstices of those bodies composing strata, must be in a stagnating state; consequently, it can only act upon the surfaces of those cavities which are to be filled up. but with what are they to be filled? not with water; they are full of that already: not with the substance of the bodies which contain that water; this would be only to make one cavity in order to fill up another. if, therefore, the cavities of the strata are to be filled with solid matter, by means of water, there must be made to pass through those porous masses, water impregnated with some other substances in a dissolved state; and the aqueous menstruum must be made to separate from the dissolved substance, and to deposit the same in those cavities through which the solution moves. by such a supposition as this, we might perhaps explain a partial consolidation of those strata; but this is a supposition, of which the case under consideration does not admit; for in the present case, which is that of materials accumulated at the bottom of the ocean, there is not proper means for separating the dissolved matter from the water included in those enormous masses; nor are there any means by which a circulation in those masses may be formed. in this case, therefore, where the means are not naturally in the supposition, a philosopher, who is to explain the phenomenon by the natural operation of water in this situation, must not have recourse to another agent, still more powerful, to assist his supposition which cannot be admitted. thus, it will appear, that, to consolidate strata formed at the bottom of the sea, in the manner now considered, operations are required unnatural to this place; consequently, not to be supposed, in order to support a hypothesis. but now, instead of inquiring how far water may be supposed instrumental in the consolidation of strata which were originally of a loose texture, we are to consider how far there may be appearances in those consolidated bodies, by which it might be concluded, whether or not the present state of their consolidation has been actually brought about by means of that agent. if water had been the menstruum by which the consolidating matter was introduced into the interstices of strata, masses of those bodies could only be found consolidated with such substances as water is capable of dissolving; and these substances would be found only in such a state as the simple separation of the solvent water might produce. in this case, the consolidation of strata would be extremely limited; for we cannot allow more power to water than we find it has in nature; nor are we to imagine to ourselves unlimited powers in bodies, on purpose to explain those appearances by which we should be made to know the powers of nature. let us, therefore, attend, with every possible circumspection, to the appearances of those bodies, by means of which we are to investigate the principles of mineralogy, and know the laws of nature. the question now before us concerns the consolidating substances of strata. are these such as will correspond to the dissolving power of water, and to the state in which these substances might be left by the separation of their menstruum? no; far, far from this supposition is the conclusion that necessarily follows from natural appearances. we have strata consolidated by calcareous spar, a thing perfectly distinguishable from the stalactical concretion of calcareous earth, in consequence of aqueous solution. we have strata made solid by the formation of fluor, a substance not soluble, so far as we know, by water. we have strata consolidated with sulphureous and bituminous substances, which do not correspond to the solution of water. we have strata consolidated with siliceous matter, in a state different from that under which it has been observed, on certain occasions, to be deposited by water. we have strata consolidated by feld-spar, a substance insoluble in water. we have strata consolidated by almost all the various metallic substances, with their almost endless mixtures and sulphureous compositions; that is to say, we find, perhaps, every different substance introduced into the interstices of strata which had been formed by subsidence at the bottom of the sea. if it is by means of water that those interstices have been filled with those materials, water must be, like fire, an universal solvent, or cause of fluidity, and we must change entirely our opinion of water in relation to its chemical character. but there is no necessity thus to violate our chemical principles, in order to explain certain natural appearances; more especially if those appearances may be explained in another manner, consistently with the known laws of nature. if, again, it is by means of heat and fusion that the loose and porous structure of strata shall be supposed to have been consolidated, then every difficulty which had occurred in reasoning upon the power or agency of water is at once removed. the loose and discontinuous body of a stratum may be closed by means of softness and compression; the porous structure of the materials may be consolidated, in a similar manner, by the fusion of their substance; and foreign matter may be introduced into the open structure of strata, in form of steam or exhalation, as well as in the fluid state of fusion; consequently, heat is an agent competent for the consolidation of strata, which water alone is not. if, therefore, such an agent could be found acting in the natural place of strata, we must pronounce it proper to bring about that end. the examination of nature gives countenance to this supposition, so far as strata are found consolidated by every species of substance, and almost every possible mixture of those different substances; consequently, however difficult it may appear to have this application of heat, for the purpose of consolidating strata formed at the bottom of the ocean, we cannot, from natural appearances, suppose any other cause, as having actually produced the effects which are now examined. this question, with regard to the means of consolidating the strata of the globe, is, to natural history, of the greatest importance; and it is essential in the theory now proposed to be given of the mineral system. it would, therefore, require to be discussed with some degree of precision in examining the particulars; but of these, there is so great a field, and the subject is so complicated in its nature, that volumes might be written upon particular branches only, without exhausting what might be laid upon the subject; because the evidence, though strong in many particulars, is chiefly to be enforced by a multitude of facts, conspiring, in a diversity of ways, to point out one truth, and by the impossibility of reconciling all these facts, except by means of one supposition. but, as it is necessary to give some proof of that which is to be a principle in our reasoning afterwards, i shall now endeavour to generalise the subject as much as possible, in order to answer that end, and, at the same time, to point out the particular method of inquiry. there are to be found, among the various strata of the globe, bodies formed of two different kinds of substances, _siliceous_ bodies, and those which may be termed _sulphureous_ or _phlogistic_. with one or other, or both of those we substances, every different consolidated stratum of the globe will be found so intimately mixed, or closely connected, that it must be concluded, by whatever cause those bodies of siliceous and sulphureous matter had been changed from a fluid to a concreted state, the strata must have been similarly affected by the same cause. these two species of bodies, therefore, the siliceous and the sulphureous, may now be examined, in relation to the causes of their concretion, with a view to determine, what has been the general concreting or consolidating power, which has operated universally in the globe; and particularly to show, it has not been by means of any fluid solution, that strata in general have been consolidated, or that those particular substances have been crystallized and concreted. siliceous matter, physically speaking, is not soluble in water; that is to say, in no manner of way have we been enabled to learn, that water has the power of dissolving this matter. many other substances, which are so little soluble in water, that their solubility could not be otherwise detected of themselves, are made to appear soluble by means of siliceous matter; such is feld-spar, one of the component parts of rock-granite. feld-spar is a compound of siliceous, argillaceous, and calcareous earth, intimately united together. this compound siliceous body being, for ages, exposed to the weather, the calcareous part of it is dissolved, and the siliceous part is left in form of a soft white earth. but whether this dissolution is performed by pure water, or by means also of an acid, may perhaps be questioned. this, however, is certain, that we must consider siliceous substances as insoluble in water. the water of glezer in iceland undoubtedly contains this substance in solution; but there is no reason to believe, that it is here dissolved by any other than the natural means; that is, an alkaline substance, by which siliceous bodies may be rendered soluble in water[ ]. [note : this conjecture, which i had thus formed, has been fully confirmed by the accurate analysis of those waters. see vol. d. of the phil. trans. of edin.] it may be, therefore, asserted, that no siliceous body having the hardness of flint, nor any crystallization of that substance, has ever been formed, except by fusion. if, by any art, this substance shall be dissolved in simple water, or made to crystallise from any solution, in that case, the assertion which has been here made may be denied. but where there is not the vestige of any proof, to authorise the supposition of flinty matter being dissolved by water, or crystallized from that solution, such an hypothesis cannot be admitted, in opposition to general and evident appearances[ ]. [note : the chevalier de dolomieu has imagined an ingenious theory for the solution of siliceous substances in water [journal de physique, mai .]. this theory has not been taken up merely at a venture, but is founded upon very accurate and interesting chemical experiments. hitherto, however, the nature of the siliceous substance is not sufficiently known, to enable us to found, upon chemical principles, the mineral operations of nature. that siliceous substance may be dissolved, or rendered soluble in water, by means of alkaline salt, and that it may be also volatilised by means of the fluor acid, is almost all that we know upon the subject. but this is saying no more in relation to the mineral operations employed upon the siliceous substance, than it would be, in relation to those upon gold, to say that this metal is dissolved by aqua regia. it is to be admitted, that every simple substance may have its menstruum, by means of which it may be retained with water in a dissolved state; but from this it does not follow, that it is by the means of aqueous solutions of all those mineral bodies, that nature operates the consolidation of bodies, which we find actually accomplished with all those different substances. it is the business of this work to show, that from all appearances in the mineral regions, as well as those upon the surface in the atmosphere, the supposition, of that manner of consolidating bodies by solution, is inconsistent both with natural appearances, and also with chemical principles. our ingenious author, who has, with, great diligence as well as an enlightened mind, observed the operations of nature upon the surface of the earth, here says, "ce n'est pas sans étonnement que je remarque depuis long-temps que jamais aucune eau qui coule à la surface de la terre n'attaque le quartz, aucune n'en tient en dissolution, pendant que celles qui circulent intérieurement le corrodent aussi souvent qu'elles le déposent."--how dangerous it is in science for ingenious men to allow themselves to form conclusions, which the principles on which they reason do not strictly warrant, we have a remarkable example in the present case. m. de dolomieu sees no corrosion of quartz, or solution of that substance, upon the surface of the earth; from this, then, he concludes, that siliceous substance is not dissolved in that situation of things. on the other hand, he finds siliceous bodies variously concreted among the solid strata of the earth; and, from this he concludes, that siliceous substance has been both dissolved by water in the strata, and also there again concreted and crystallised in having been separated from the water. this is certainly what we all perceive; but we do not all allow ourselves to draw such inconclusive inferences from our premises. notwithstanding the greatest accuracy of our observations, quartz may be dissolvable in a minute degree by water, upon the surface of this earth; and, all the appearances of siliceous bodies, in the mineral regions, where we cannot immediately see the operation, may be better explained by fusion than by aqueous solution. but, from his chemical experiments, our author has conjectured that there may be a phlogistic substance, by means of which the siliceous earth is dissolved when in darkness; and that this solvent loses its power, if exposed to the light of day. i have one observation to oppose to this ingenious theory. under deep black mosses, through which no ray of light can penetrate, every condition for dissolving siliceous bodies should be found, according to the supposition in question; neither will sufficient time be found wanting, in those deep mosses, upon the summits of our mountains; yet, examine the matter of fact? not the smallest solution is to be perceived in the siliceous parts of the stones which are found under those mosses, but every particle of iron is dissolved, so that the surface of every stone is white, and nothing but the siliceous earth of the feld-spar, and perhaps the argillaceous, is left. here we have in this author an instructive example: no person, in my opinion, has made such enlightened or scientific experiments, or such judicious observations with regard to the nature of siliceous substance, as a compound thing; no person reasons more distinctly in general, or sees more clearly the importance of his principles; yet, with regard to mineral concretions, how often has he been drawn thus inadvertently into improper generalization! i appeal to the analogy which, in this treatise, he has formed, between the stalactical concretions upon the surface of the earth, and the mineral concretions of siliceous substance. as an example of the great lights, and penetrating genius, of this assiduous studier of nature, i refer to the judicious observations which he has made upon the subject of aluminous earth, in this dissertation. i am surprised to find this enlightened naturalist seeking, in the origin of this globe of our earth, a general principle of fluidity or solution in water, like the alkahest of the alchymists, by means of which the different substances in the chemical constitution of precious stones might have been united as well as crystallised. one would have thought, that a philosopher, so conversant in the operations of subterraneous fire, would have perceived, that there is but one general principle of fluidity or dissolution, and that this is heat.] besides this proof for the fusion of siliceous bodies, which is indirect, arising from the in dissolubility of that substance in water, there is another, which is more direct, being founded upon appearances which are plainly inconsistent with any other supposition, except that of simple fluidity induced by heat. the proof i mean is, the penetration of many bodies with a flinty substance, which, according to every collateral circumstance, must have been performed by the flinty matter in a simply fluid state, and not in a state of dissolution by a solvent. these are flinty bodies perfectly insulated in strata both of chalk and sand. it requires but inspection to be convinced. it is not possible that flinty matter could be conveyed into the middle of those strata, by a menstruum in which it was dissolved, and thus deposited in that place, without the smallest trace of deposition in the surrounding parts. but, besides this argument taken from what does not appear, the actual form in which those flinty masses are found, demonstrates, _first_, that they have been introduced among those strata in a fluid state, by injection from some other place. _dly_, that they have been dispersed in a variety of ways among those strata, then deeply immersed at the bottom of the sea; and, _lastly_, that they have been there congealed from the state of fusion, and have remained in that situation, while those strata have been removed from the bottom of the ocean to the surface of the present land. to describe those particular appearances would draw this paper beyond the bounds of an essay. we must, therefore, refer those who would inquire more minutely into the subject, to examine the chalk-countries of france and england, in which the flint is found variously formed; the land-hills interspersed among those chalk-countries, which have been also injected by melted flint; and the pudding-stone of england, which i have not seen in its natural situation. more particularly, i would recommend an examination of the insulated masses of stone, found in the sand-hills by the city of brussels; a stone which is formed by an injection of flint among sand, similar to that which, in a body of gravel, had formed the pudding-stone of england[ ]. [note : accurate descriptions of those appearances, with drawings, would be, to natural history, a valuable acquisition.] all these examples would require to be examined upon the spot, as a great part of the proof for the fusion of the flinty substance, arises, in my opinion, from the form in which those bodies are found, and the state of the surrounding parts. but there are specimens brought from many different places, which contain, in themselves, the most evident marks of this injection of the flinty substance in a fluid state. these are pieces of fossil wood, penetrated with a siliceous substance, which are brought from england, germany, and lochneagh in ireland. it appears from these specimens, that there has sometimes been a prior penetration of the body of wood, either with irony matter, or calcareous substance. sometimes, again, which is the case with that of lochneagh, there does not seem to have been any penetration of those two substances. the injected flint appears to have penetrated the body of this wood, immersed at the bottom of the sea, under an immense compression of water. this appears from the wood being penetrated partially, some parts not being penetrated at all. now, in the limits between those two parts, we have the most convincing proofs, that it had been flint in a simple fluid state which had penetrated the wood, and not in a state of solution. _first_, because, however little of the wood is left unpenetrated, the division is always distinct between the injected part and that which is not penetrated by the fluid flint. in this case, the flinty matter has proceeded a certain length, which is marked, and no farther; and, beyond this boundary, there is no partial impregnation, nor a gradation of the flintifying operation, as must have been the case if siliceous matter had been deposited from a solution. _dly_, the termination of the flinty impregnation has assumed such a form, precisely, as would naturally happen from a fluid flint penetrating that body. in other specimens of this mineralising operation, fossil wood, penetrated, more or less, with ferruginous and calcareous substances, has been afterwards penetrated with a flinty substance. in this case, with whatever different substances the woody body shall be supposed to have been penetrated in a state of solution by water, the regular structure of the plant would still have remained, with its vacuities, variously filled with the petrifying substances, separated from the aqueous menstruum, and deposited in the vascular structure of the wood. there cannot be a doubt with regard to the truth of this proposition; for, as it is, we frequently find parts of the consolidated wood, with the vascular structure remaining perfectly in its natural shape and situation; but if it had been by aqueous solution that the wood had been penetrated and consolidated, all the parts of that body would be found in the same natural shape and situation. this, however, is far from being the case; for while, in some parts, the vascular structure is preserved entire, it is also evident, that, in general, the woody structure is variously broken and dissolved by the fusion and crystallization of the flint. there are so many and such various convincing examples of this, that, to attempt to describe them, would be to exceed the bounds prescribed for this dissertation; but such specimens are in my possession, ready for the inspection of any person who may desire to study the subject. we may now proceed to consider sulphureous substances, with regard to their solubility in water, and to the part which these bodies have acted in consolidating the strata of the globe. the sulphureous substances here meant to be considered, are substances not soluble in, water, so far as we know, but fusible by heat, and inflammable or combustible by means of heat and vital air. these substances are of two kinds; the one more simple, the other more compound. the most simple kind is composed of two different substances, viz. phlogiston, with certain specific substances; from which result, on the one hand, sulphur, and, on the other, proper coal and metals. the more compound sort, again, is oily matter, produced by vegetables, and forming bituminous bodies. the _first_ of these is found naturally combined with almost all metallic substances, which are then said to be mineralised with sulphur. now, it is well known, that this mineralising operation is performed by means of heat or fusion; and there is no person skilled in chemistry that will pretend to say, this may be done by aqueous solution. the combination of iron and sulphur, for example, may easily be performed by fusion; but, by aqueous solution, this particular combination is again resolved, and forms an acido-metallic, that is, a vitriolic substance, after the phlogiston (by means of which it is insoluble in water) has been separated from the composition, by the assistance of vital air. the variety of these sulphureo-metallic substances, in point of composition, is almost indefinite; but, unless they were all soluble in water, this could not have happened by the action of that solvent. if we shall allow any one of those bodies to have been formed by the fluidity of heat, they must all have been formed in the same manner; for there is such a chain of connection among those bodies in the mineral regions, that they must all have been composed, either, on the one hand, by aqueous solution, or, on the other, by means of heat and fusion. here, for example, are crystallised together in one mass, _st, pyrites_, containing sulphur, iron, copper; _dly, blend_, a composition of iron, sulphur, and calamine; _dly, galena_, consisting of lead and sulphur; _thly, marmor metallicum_, being the terra ponderosa, saturated with the vitriolic acid; a substance insoluble in water; _thly, fluor_, a saturation of calcareous earth, with a peculiar acid, called the _acid of spar_, also insoluble in water; _thly, calcareous spar_, of different kinds, being calcareous earth saturated with fixed air, and something besides, which forms a variety in this substance; _lastly, siliceous substance_, or _quartz crystals_. all these bodies, each possessing its proper shape, are mixed in such a manner as it would be endless to describe, but which may be expressed in general by saying, that they are mutually contained in, and contain each other. unless, therefore; every one of these different substances may be dissolved in water, and crystallised from it, it is in vain to look for the explanation of these appearances in the operations of nature, by the means of aqueous solution. on the other hand, heat being capable of rendering all these substances fluid, they may be, with the greatest simplicity, transported from one place to another; and they may be made to concrete altogether at the same time, and distinctly separate in any place. hence, for the explanation of those natural appearances, which are so general, no further conditions are required, than the supposition of a sufficient intensity of subterraneous fire or heat, and a sufficient degree of compression upon those bodies, which are to be subjected to that violent heat, without calcination or change. but, so far as this supposition is not gratuitous, the appearances of nature will be thus explained. i shall only mention one specimen, which must appear most decisive of the question. it is, i believe, from an hungarian mine. in this specimen, petro-silex, pyrites, and cinnabar, are so mixed together, and crystallised upon each other, that it is impossible to conceive any one of those bodies to have had its fluidity and concretion from a cause which had not affected the other two. now, let those who would deny the fusion of this siliceous body explain how water could dissolve these three different bodies, and deposit them in their present shape. if, on the contrary, they have not the least shadow of reason for such a gratuitous supposition, the present argument must be admitted in its full force. sulphur and metals are commonly found combined in the mineral regions. but this rule is not universal; for they are also frequently in a separate state. there is not, perhaps, a metal, among the great number which are now discovered, that may not be found native, as they are called, or in their metallic state. metallic substances are also thus found in some proportion to the disposition of the particular metals, to resist the mineralising operations, and to their facility of being metallised by fire and fusion. gold, which refuses to be mineralised with sulphur, is found generally in its native state. iron, again, which is so easily mineralised and scorified, is seldom found in its malleable state. the other metals are all found more or less mineralised, though some of them but rarely in the native state. besides being found with circumstances thus corresponding to the natural facility, or to the impediments attending the metallization of those different calces, the native metals are also found in such a shape, and with such marks, as can only agree with the fusion of those bodies; that is to say, those appearances are perfectly irreconcilable with any manner of solution and precipitation. for the truth of this assertion, among a thousand other examples, i appeal to that famous mass of native iron discovered by mr pallas in siberia. this mass being so well known to all the mineralists of europe, any comment upon its shape and structure will be unnecessary[ ]. [note : since this dissertation was written, m. de la peyrouse has discovered a native manganese. the circumstances of this mineral are so well adapted for illustrating the present doctrine, and so well related by m. de la peyrouse, that i should be wanting to the interest of mineral knowledge, were i not to give here that part of his memoir. "lorsque je fis insérer dans le journal de physique de l'année , au mois de janvier, une dissertation contenant la classification des mines de manganèse, je ne connoissois point, à cette époque, la mine de manganèse native. elle a la couleur de son régule: elle salit les doigts de la même teinte. son tissu parait aussi lamelleux, et les lames semblent affecter une sorte de divergence. elle a ainsi que lui, l'éclat métallique; comme lui elle se laisse aplatir sous le marteau, et s'exfolie si l'on redouble les coups; mais une circonstance qui est trop frappante pour que je l'omette, c'est la figure de la manganèse native, si prodigieusement conforme à celle du régule, qu'on s'y laisseroit tromper, si la mine n'étoit encore dans sa gangue: figure très-essentielle à observer ici, parce qu'elle est due à la nature même de la manganèse. en effet, pour réduire toutes les mines en général, il faut employer divers flux appropriés. pour la réduction de la manganèse, bien loin d'user de ce moyen, il faut, au contraire, éloigner tout flux, produire la fusion, par la seule violence et la promptitude du feu. et telle est la propension naturelle et prodigieuse de la manganèse à la vitrification, qu'on n'a pu parvenir encore à réduire son régule en un seul culot; on trouve dans le creuset plusieurs petits boutons, qui forment autant de culots séparés. dans la mine de manganèse native, elle n'est point en une seule masse; elle est disposée également en plusieurs culots séparés, et un peu aplatis, comme ceux que l'art produit; beaucoup plus gros, à la vérité, parce que les agens de la nature doivent avoir une autre énergie, que ceux de nos laboratoires; et cette ressemblance si exacte, semble devoir vous faire penser que la mine native à été produite par le feu, tout comme son régule. la présence de la chaux argentée de la manganèse, me permettroit de croire que la nature n'a fait que réduire cette chaux. du reste, cette mine native est très-pure, et ne contient aucune partie attirable à l'aimant. cette mine, unique jusqu'à ce moment, vient, tout comme les autres manganèse que j'ai décrites, des mines de fer de _sem_, dans la vallée de _viedersos_, en comté de foix."--_journal de physique, janvier _.] we come now to the _second_ species of inflammable bodies called oily or bituminous. these substances are also found variously mixed with mineral bodies, as well as forming strata of themselves; they are, therefore, a proper subject for a particular examination. in the process of vegetation, there are produced oily and resinous substances; and, from the collection of these substances at the bottom of the ocean, there are formed strata, which have afterwards undergone various degrees of beat, and have been variously changed, in consequence of the effects of that heat, according as the distillation of the more volatile parts of those bodies has been suffered to proceed. in order to understand this, it must be considered, that, while immersed in water, and under insuperable compression, the vegetable, oily, and resinous substances, would appear to be unalterable by heat; and it is only in proportion as certain chemical separations take place, that these inflammable bodies are changed in their substance by the application of heat. now, the most general change of this kind is in consequence of evaporation, or the distillation of their more volatile parts, by which oily substances become bituminous, and bituminous substances become coaly. there is here a gradation which may be best understood, by comparing the extremes. on the one hand, we know by experiment, that oily and bituminous substances can be melted and partly changed into vapour by heat, and that they become harder and denser, in proportion as the more volatile parts have evaporated from them. on the other hand, coaly substances are destitute of fusibility and volatility, in proportion as they have been exposed to greater degrees of heat, and to other circumstances favourable to the dissipation of their more volatile and fluid parts. if, therefore, in mineral bodies, we find the two extreme states of this combustible substance, and also the intermediate states, we must either conclude, that this particular operation of heat has been thus actually employed in nature, or we must explain those appearances by some other means, in as satisfactory a manner, and so as shall be consistent with other appearances. in this case, it will avail nothing to have recourse to the false analogy of water dissolving and crystallising salts, which has been so much employed for the explanation of other mineral appearances. the operation here in question is of a different nature, and necessarily requires both the powers of heat and proper conditions for evaporation. therefore, in order to decide the point, with regard to what is the power in nature by which mineral bodies have become solid, we have but to find bituminous substance in the most complete state of coal, intimately connected with some other substance, which is more generally found consolidating the strata, and assisting in the concretion of mineral substances. but i have in my possession the most undoubted proof of this kind. it is a mineral vein, or cavity, in which are blended together coal of the most fixed kind, quartz and marmor metallicum. nor is this all; for the specimen now referred to is contained in a rock of this kind, which every naturalist now-a-days will allow to have congealed from a fluid state of fusion. i have also similar specimens from the same place, in which the coal is not of that fixed and infusible kind which burns without flame or smoke, but is bituminous or inflammable coal. we have hitherto been resting the argument upon a single point, for the sake of simplicity or clearness, not for want of those circumstances which shall be found to corroborate the theory. the strata of fossil coal are found in almost every intermediate state, as well as in those of bitumen and charcoal. of the one kind is that fossil coal which melts or becomes fluid upon receiving heat; of the other, is that species of coal, found both in wales and scotland, which is perfectly infusible in the fire, and burns like coals, without flame or smoke. the one species abounds in oily matter, the other has been distilled by heat, until it has become a _caput mortuum_, or perfect coal. the more volatile parts of these bituminous bodies are found in their separate state on some occasions. there is a stratum of limestone in fifeshire, near raith, which, though but slightly tinged with a black colour, contains bituminous matter, like pitch, in many cavities, which are lined with calcareous spar crystallised. i have a specimen of such a cavity, in which the bitumen is in sphericles, or rounded drops, immersed in the calcareous spar. now, it is to be observed, that, if the cavity in the solid limestone or marble, which is lined with calcareous crystals containing pyrites, had been thus encrusted by means of the filtration of water, this water must have dissolved calcareous spar, pyrites, and bitumen. but these natural appearances would not even be explained by this dissolution and supposed filtration of those substances. there is also required, _first_, a cause for the separation of those different substances from the aqueous menstruum in which they had been dissolved; _ dly_, an explanation of the way in which a dissolved bitumen should be formed into round hard bodies of the most solid structure; and, _lastly_, some probable means for this complicated operation being performed, below the bottom of the ocean, in the close cavity of a marble stratum. thus, the additional proof, from the facts relating to the bituminous substances, conspiring with that from the phenomena of other bodies, affords the strongest corroboration of this opinion, that the various concretions found in the internal parts of strata have not been occasioned by means of aqueous solution, but by the power of heat and operation of simple fusion, preparing those different substances to concrete and crystallise in cooling. the arguments which have been now employed for proving that strata have been consolidated by the power of heat, or by the means of fusion, have been drawn chiefly from the insoluble nature of those consolidating substances in relation to water, which is the only general menstruum that can be allowed for the mineral regions. but there are found, in the mineral kingdom, many solid masses of saltgem, which is a soluble substance. it may be now inquired, how far these masses, which are not infrequent in the earth, tend either to confirm the present theory, or, on the contrary, to give countenance to that which supposes water the chief instrument in consolidating strata. the formation of salt at the bottom of the sea, without the assistance of subterranean fire, is not a thing unsupposable, as at first sight it might appear. let us but suppose a rock placed across the gut of gibraltar, (a case nowise unnatural), and the bottom of the mediterranean would be certainly filled with salt, because the evaporation from the surface of that sea exceeds the measure of its supply. but strata of salt, formed in this manner at the bottom of the sea, are as far from being consolidated by means of aqueous solution, as a bed of sand in the same situation; and we cannot explain the consolidation of such a stratum of salt by means of water, without supposing subterranean heat employed, to evaporate the brine which would successively occupy the interstices of the saline crystals. but this, it may be observed, is equally departing from the natural operation of water, as the means for consolidating the sediment of the ocean, as if we were to suppose the same thing done by heat and fusion. for the question is not, if subterranean heat be of sufficient intensity for the purpose of consolidating strata by the fusion of their substances; the question is, whether it be by means of this agent, subterranean heat, or by water alone, without the operation of a melting heat, that those materials have been variously consolidated. the example now under consideration, consolidated mineral salt, will serve to throw some light upon the subject; for, as it is to be shown, that this body of salt had been consolidated by perfect fusion, and not by means of aqueous solution, the consolidation of strata of indissoluble substances, by the operation of a melting heat, will meet with all that confirmation which the consistency of natural appearances can give. the salt rock in cheshire lies in strata of red marl. it is horizontal in its direction. i do not know its thickness, but it is dug thirty or forty feet deep. the body of this rock is perfectly solid, and the salt, in many places, pure, colourless, and transparent, breaking with a sparry cubical structure. but the greatest part is tinged by the admixture of the marl, and that in various degrees, from the slightest tinge of red, to the most perfect opacity. thus, the rock appears as if it had been a mass of fluid salt, in which had been floating a quantity of marly substance, not uniformly mixed, but every where separating and subsiding from the pure saline substance. there is also to be observed a certain regularity in this separation of the tinging from the colourless substance, which, at a proper distance, gives to the perpendicular section of the rock a distinguishable figure in its structure. when looking at this appearance near the bottom of the rock, it, at first, presented me with the figure of regular stratification; but, upon examining the whole mass of rock, i found, that it was only towards the bottom that this stratified appearance took place; and that, at the top of the rock, the most beautiful and regular figure was to be observed; but a figure the most opposite to that of stratification. it was all composed of concentric circles; and these appeared to be the section of a mass, composed altogether of concentric spheres, like those beautiful systems of configuration which agates so frequently present us with in miniature. in about eight or ten feet from the top, the circles growing large, were blended together, and gradually lost their regular appearance, until, at a greater depth, they again appeared in resemblance of a stratification. this regular arrangement of the floating marly substance in the body of salt, which is that of the structure of a coated pebble, or that of concentric spheres, is altogether inexplicable upon any other supposition, than the perfect fluidity or fusion of the salt, and the attractions and repulsions of the contained substances. it is in vain to look, in the operations of solution and evaporation, for that which nothing but perfect fluidity or fusion can explain. this example of a mineral salt congealed from a melted state, may be confirmed from another which i have from dr black, who suggested it to me. it is an alkaline salt, found in a mineral state, and described in the philosophical transactions, _anno_ . but to understand this specimen, something must be premised with regard to the nature of fossil alkali. the fossil alkali crystallises from a dissolved state, in combining itself with a large portion of the water, in the manner of alum; and, in this case, the water is essential to the constitution of that transparent crystalline body; for, upon the evaporation of the water, the transparent salt loses its solidity, and becomes a white powder. if, instead of being gently dried, the crystalline salt is suddenly exposed to a sufficient degree of heat, that is, somewhat more than boiling water, it enters into the state of aqueous fusion, and it boils, in emitting the water by means of which it had been crystallised in the cold, and rendered fluid in that heated state. it is not possible to crystallise this alkaline salt from a dissolved state, without the combination of that quantity of water, nor to separate that water without destroying its crystalline state. but in this mineral specimen, we have a solid crystalline salt, with a structure which, upon fracture, appears to be sparry and radiated, something resembling that of zeolite. it contains no water in its crystallization, but melts in a sufficient heat, without any aqueous fusion. therefore, this salt must have been in a fluid state of fusion, immediately before its congelation and crystallization. it would be endless to give examples of particular facts, so many are the different natural appearances that occur, attended with a variety of different circumstances. there is one, however, which is peculiarly distinct, admits of sufficiently accurate description, and contains circumstances from which conclusions may be drawn with clearness. this is the ironstone, which is commonly found among the argillaceous strata, attendant upon fossil coal, both in scotland and in england. this stone is generally found among the bituminous schistus, or black argillaceous strata, either in separate masses of various shapes and sizes, or forming of itself strata which are more or less continuous in their direction among the schistous or argillaceous beds. this mineral contains, in general, from to _per cent._ of iron, and it loses near one third of its weight in calcination. before calcination it is of a grey colour, is not penetrable by water, and takes a polish. in this state, therefore, it is perfectly solid; but being calcined, it becomes red, porous, and tender. the fact to be proved with regard to these iron-stones is this, that they have acquired their solid state from fusion, and not in concreting from any aqueous solution. to abridge this disquisition, no argument is to be taken from contingent circumstances, (which, however, are often found here as well as in the case of marbles); such only are to be employed as are general to the subject, and arise necessarily from the nature of the operation. it will be proper to describe a species of these stones, which is remarkably regular in its form. it is that found at aberlady, in east lothian. the form of these iron-stones is that of an oblate or much compressed sphere, and the size from two or three inches diameter to more than a foot. in the circular or horizontal section, they present the most elegant septarium[ ]; and, from the examination of this particular structure, the following conclusions may be drawn. _first_, that, the septa have been formed by the uniform contraction of the internal parts of the stone, the volume of the central parts diminishing more than that of the circumference; by this means, the separations of the stone diminish, in a progression from the center towards the circumference. _ d_, that there are only two ways in which the septa must have received the spar or spatthose ore with which they are filled, more or less, either, _first_ by insinuation into the cavity of the septa after these were formed; or, _ dly_, by separation from the substance of the stone, at the same time that the septa were forming. [note : plate i.] were the first supposition true, appearances would be observable, showing that the sparry substance had been admitted, either through the porous structure of the stone, or through proper apertures communicating from without. now, if either one or other of these had been the case, and that the stone had been consolidated from no other cause than concretion from a dissolved state, that particular structure of the stone, by means of which the spar had been admitted, must appear at present upon an accurate examination. this, however, is not the case, and we may rest the argument here. the septa reach not the circumference; the surface of the stone is solid and uniform in every part; and there is not any appearance of the spar in the argillaceous bed around the stone. it, therefore, necessarily follows, that the contraction of the iron-stone, in order to form septa, and the filling of these cavities with spar, had proceeded _pari passu_; and that this operation must have been brought about by means of fusion, or by congelation from a state of simple fluidity and expansion. it is only further to be observed, that all the arguments which have been already employed, concerning mineral concretions from a simply fluid state, or that of fusion, here take place. i have septaria of this kind, in which, besides pyrites, iron-ore, calcareous spar, and another that is ferruginous and compound, there is contained siliceous crystals; a case which is not so common. i have them also attended with circumstances of concretion and crystallization, which, besides being extremely rare, are equally curious and interesting. there is one fact more which is well worth our attention, being one of those which are so general in the mineral regions. it is the crystallizations which are found in close cavities of the most solid bodies. nothing is more common than this appearance. cavities are every where found closely lined with crystallizations, of every different substance which may be supposed in those places. these concretions are well known to naturalists, and form part of the beautiful specimens which are preserved in the cabinets of collectors, and which the german mineralists have termed _drusen_. i shall only particularise one species, which may be described upon principle, and therefore may be a proper subject on which to reason, for ascertaining the order of production in certain bodies. this body, which we are now to examine, is of the agate species. we have now been considering the means employed by nature in consolidating strata which were originally of an open structure; but in perfectly solid strata we find bodies of agate, which have evidently been formed in that place where they now are found. this fact, however, is not still that of which we are now particularly to inquire; for this, of which we are to treat, concerns only a cavity within this agate; now, whatever may have been the origin of the agate itself, we are to show, from what appears within its cavity, that the crystallizations which are found in this place had arisen from a simply fluid state, and not from that of any manner of solution. the agates now in question are those of the coated kind, so frequent in this country, called pebbles. many of these are filled with a siliceous crystallization, which evidently proceeds from the circumference towards the centre. many of them, again, are hollow. those cavities are variously lined with crystallized substances; and these are the object of the present examination. but before describing what is found within, it is necessary to attend to this particular circumstance, that the cavity is perfectly inclosed with many solid coats, impervious to air or water, but particularly with the external cortical part, which is extremely hard, takes the highest polish, and is of the most perfect solidity, admitting the passage of nothing but light and heat. within these cavities, we find, _ st_, the coat of crystals with which this cavity is always lined; and this is general to all substances concreting, in similar circumstances, from a state of fusion; for when thus at liberty they naturally crystallise. _ dly_, we have frequently a subsequent crystallization, resting on the first, and more or less immersed in it. _ dly_, there is also sometimes a third crystallization, superincumbent on the second, in like manner as the second was on the first. i shall mention some particulars. i have one specimen, in which the primary crystals are siliceous, the secondary thin foliaceous crystals of deep red but transparent iron-ore, forming elegant figures, that have the form of roses. the tertiary crystallization is a frosting of small siliceous crystals upon the edges of the foliaceous crystals. in other specimens, there is first a lining of colourless siliceous crystals, then another lining of amethystine crystals, and sometimes within that, fuliginous crystals. upon these fuliginous and amethystine crystals are many sphericles or hemispheres of red compact iron-ore, like haematites. in others, again, the primary crystals are siliceous, and the secondary calcareous. of this kind, i have one which has, upon the calcareous crystals, beautiful transparent siliceous crystals, and iron sphericles both upon all these crystals, and within them. _lastly_, i have an agate formed of various red and white coats, and beautifully figured. the cavity within the coated part of the pebble is filled up without vacuity, first, with colourless siliceous crystals; secondly, with fuliginous crystals; and, lastly, with white or colourless calcareous spar. but between the spar and crystals there are many sphericles, seemingly of iron, half sunk into each of these two different substances. from these facts, i may now be allowed to draw the following conclusions: _st_, that concretion had proceeded from the surface of the agate body inwards. this necessarily follows from the nature of those figured bodies, the figures of the external coats always determining the shape of those within, and never, contrarily, those within affecting those without. _dly_, that when the agate was formed, the cavity then contained every thing which now is found within it, and nothing more. _dly_, that the contained substances must have been in a fluid state, in order to their crystallizing. _lastly_, that as this fluid state had not been the effect of solution in a menstruum, it must have been fluidity from heat and fusion. let us now make one general observation and argument with regard to the formation of those various coated, concreted, crystallized, and configured bodies. were the crystallization and configuration found to proceed from a central body, and to be directed from that centre outwards, then, without inquiring into collateral appearances, and other proofs with regard to the natural concretion of those substances, we might suppose that these concretions might have proceeded from that central body gradually by accretion, and that the concreting and crystallizing substances might have been supplied from a fluid which had before retained the concreting substance in solution; in like manner as the crystallizations of sugar, which are formed in the solution of that saccharine substance, and are termed candies, are formed upon the threads which are extended in the crystallizing vessel for that purpose. but if, on the contrary, we are to consider those mineral bodies as spheres of alternate coats, composed of agate, crystal, spars, etc.; and if all those crystallizations have their _bases_ upon the uncrystallized coat which is immediately external to it, and their _apices_ turned inwards into the next internal solid coat, it is not possible to conceive that a structure of this kind could have been formed in any manner from a solution. but this last manner is the way without exception in which those mineral bodies are found; therefore we are to conclude, that the concretion of those bodies had proceeded immediately from a state of fusion or simple fluidity. in granite these cavities are commonly lined with the crystal corresponding to the constituent substances of the stone, viz. quartz, feld-spar, and mica or talk. m. de saussure, (voyages dans les alpes, tom. ii. § .), says, "on trouve fréquemment des amas considérables de spath calcaire, crystallisé dans les grottes ou se forme le crystal de roche; quoique ces grottes soient renfermées dans le coeur des montagnes d'un granit vif, & qu'on ne voie aucun roc calcaire au dessus de ces montagnes." so accurate an observer, and so complete a naturalist, must have observed how the extraneous substance had been introduced into this cavity, had they not been formed together the cavity and the calcareous crystals. that m. de saussure perceived no means for that introduction, will appear from what immediately follows in that paragraph. "ces rocs auroient-ils été détruits, ou bien ce spath n'est il que le produit d'une sécrétion des parties calcaires que l'on fait êtres dispersées entre les divers élémens du granit?" had m. de saussure allowed himself to suppose all those substances in fusion, of which there cannot be a doubt, he would soon have resolved both this difficulty, and also that of finding molybdena crystallized along with feld-spar, in a cavity of this kind. § . to this argument, taken from the close cavities in our agates, i am now to add another demonstration. it is the case of the calcedony agate, containing a body of calcareous spar; here it is to be shown, that, while the calcareous body was altogether inclosed within the calcedony nodular body, these two substances had been perfectly soft, and had mutually affected each others shape, in concreting from a fluid state. in order to see this, we are to consider that both those substances have specific shapes in which they concrete from the third state; the sparry structure of the one is well known; the spherical or mammelated crystallization of the calcedony, is no less conspicuous; this last is, in the present case, spherical figures, which are some of them hemispheres, or even more. the figures which we have now in contemplation are so distinctly different as cannot be mistaken; the one is a rhombic figure bounded by planes; the other is a most perfect spherical form; and both these are specific figures, belonging respectively to the crystallization of those two substances. the argument now to be employed for proving that those two bodies had concreted from the fluid state of fusion, and not from any manner of solution, is this: that, were the one of those bodies to be found impressing the other with its specific figure, we must conclude that the impressing body had concreted or crystallized while the impressed body was in a soft or fluid state; and that, if they are both found mutually impressing and impressed by each other, they must have both been in the fluid and concreting state together. now the fact is, that the calcareous body is perfectly inclosed within the solid calcedony, and that they are mutually impressed by each others specific figure, the sparry structure of the calcareous body impressing the calcedony with its type of planes and angles, at the same time that, in other parts, the spherical figures of the calcedony enter the solid body of the spar, and thus impress their mammelated figures into that part which is contiguous. it is therefore inconceivable, that these appearances could have been produced in any other manner than by those two bodies concreting from a simply fluid state. there are in jaspers and agates many other appearances, from whence the fusion of those substances may be concluded with great certainty and precision; but it is hoped, that what has been now given may suffice for establishing that proposition without any doubt. it must not be here objected, that there are frequently found siliceous crystals and amethysts containing water; and that it is impossible to confine water even in melted glass. it is true, that here, at the surface of the earth, melted glass cannot, in ordinary circumstances, be made to receive and inclose condensed water; but let us only suppose a sufficient degree of compression in the body of melted glass, and we can easily imagine it to receive and confine water as well as any other substance. but if, even in our operations, water, by means of compression, may be made to endure the heat of red hot iron without being converted into vapour, what may not the power of nature be able to perform? the place of mineral operations is not on the surface of the earth; and we are not to limit nature with our imbecility, or estimate the powers of nature by the measure of our own.[ ] [note : this is so material a principle in the theory of consolidating the strata of the earth by the fusion of mineral substances, that i beg the particular attention of the reader to that subject. the effect of compression upon compound substances, submitted to increased degrees of heat, is not a matter of supposition, it is an established principle in natural philosophy. this, like every other physical principle, is founded upon matter of fact or experience; we find, that many compound substances may with heat be easily changed, by having their more volatile parts separated when under a small compression; but these substances are preserved without change when sufficiently compressed. our experiments of this kind are necessarily extremely limited; they are not, however, for that reason, the less conclusive. the effects of increasing degrees of heat are certainly prevented by increasing degrees of compression; but the rate at which the different effects of those powers proceed, or the measure of those different degrees of increase that may be made without changing the constitution of the compound substance, are not known; nor is there any limit to be set to that operation, so far as we know. consequently, it is a physical principle, that the evaporation of volatile substances by heat, or the reparation of them from a compound substance, consequently the effect of fire in changing that compound substance, may be absolutely prevented by means of compression. it now remains to be considered, how far there is reason to conclude that there had been sufficient degrees of compression in the mineral regions, for the purpose of melting the various substances with which we find strata consolidated, without changing the chemical constitution of those compound substances. had i, in reasoning _a priori_, asserted, that all mineral bodies might have been melted without change, when under sufficient compression, there might have arisen, in the minds of reasoning men, some doubt with regard to the certainty of that proposition, however probable it were to be esteemed: but when, in reasoning _a posteriori_, it is found that all mineral bodies have been actually melted, then, all that is required to establish the proposition on which i have founded my theory, is to see that there must have been immense degrees of compression upon the subjects in question; for we neither know the degree of heat which had been employed, nor that of compression by which the effect of the heat must have been modified. now, in order to see that there had been immense compression, we have but to consider that the formation of the strata, which are to be consolidated, was at the bottom of the ocean, and that this place is to us unfathomable. if it be farther necessary to show that it had been at such unfathomable depth strata were consolidated, it will be sufficient to observe, it is not upon the surface of the earth, or above the level of the sea, that this mineral operation can take place; for, it is there that those consolidated bodies are redissolved, or necessarily going into decay, which is the opposite to that operation which we are now inquiring after; therefore, if they were consolidated in any other place than at the bottom of the sea, it must have been between that place of their formation and the surface of the sea; but that is a supposition which we have not any reason to make; therefore, we must conclude that it was at the bottom of the ocean those stratified bodies had been consolidated.] to conclude this long chemico-mineral disquisition, i have specimens in which the mixture of calcareous, siliceous, and metallic substances, in almost every species of concretion which is to be found in mineral bodies, may be observed, and in which there is exhibited, in miniature, almost every species of mineral transaction, which, in nature, is found upon a scale of grandeur and magnificence. they are nodules contained in the whin-stone, porphyry, or basaltes of the calton-hill, by edinburgh; a body which is to be afterwards examined, when it will be found to have flowed, and to have been in fusion, by the operation of subterraneous heat. this evidence, though most conclusive with regard to the application of subterraneous heat, as the means employed in bringing into fusion all the different substances with which strata may be found consolidated, is not directly a proof that strata had been consolidated by the fusion of their proper substance. it was necessary to see the general nature of the evidence, for the universal application of subterraneous heat, in the fusion of every kind of mineral body. now, that this has been done, we may give examples of strata consolidated without the introduction of foreign matter, merely by the softening or fusion of their own materials. for this purpose, we may consider two different species of strata, such as are perfectly simple in their nature, of the most distinct substances, and whose origin is perfectly understood, consequently, whose subsequent changes may be reasoned upon with certainty and clearness. these are the siliceous and calcareous strata; and these are the two prevailing substances of the globe, all the rest being, in comparison of these, as nothing; for unless it be the bituminous or coal strata, there is hardly any other which does not necessarily contain more or less of one or other of these two substances. if, therefore, it can be shown, that both of those two general strata have been consolidated by the simple fusion of their substance, no _desideratum_ or doubt will remain, with regard to the nature of that operation which has been transacted at great depths of the earth, places to which all access is denied to mortal eyes. we are now to prove, _first_, that those strata have been consolidated by simple fusion; and, _ dly_, that this operation is universal, in relation to the strata of the earth, as having produced the various degrees of solidity or hardness in these bodies. i shall first remark, that a fortuitous collection of hard bodies, such as gravel and sand, can only touch in points, and cannot, while in that hard state, be made to correspond so precisely to each others shape as to consolidate the mass. but if these hard bodies should be softened in their substance, or brought into a certain degree of fusion, they might be adapted mutually to each other, and thus consolidate the open structure of the mass. therefore, to prove the present point, we have but to exhibit specimens of siliceous and calcareous strata which have been evidently consolidated in this manner. of the first kind, great varieties occur in this country. it is, therefore, needless to describe these particularly. they are the consolidated strata of gravel and sand, often containing abundance of feld-spar, and thus graduating into granite; a body, in this respect, perfectly similar to the more regular strata which we now examine. the second kind, again, are not so common in this country, unless we consider the shells and coralline bodies in our lime-stones, as exhibiting the same example, which indeed they do. but i have a specimen of marble from spain, which may be described, and which will afford the most satisfactory evidence of the fact in question. this spanish marble may be considered as a species of pudding-stone, being formed of calcareous gravel; a species of marble which, from mr bowles' natural history, appears to be very common in spain. the gravel of which this marble is composed, consists of fragments of other marbles of different kinds. among these, are different species of _oolites_ marble, some shell marbles, and some composed of a chalky substance, or of undistinguishable parts. but it appears, that all these different marbles had been consolidated or made hard, then broken into fragments, rolled and worn by attrition, and thus collected together, along with some sand or small siliceous bodies, into one mass. lastly, this compound body is consolidated in such a manner as to give the most distinct evidence, that this had been executed by the operation of heat or simple fusion. the proof i give is this, that besides the general conformation of those hard bodies, so as to be perfectly adapted to each other's shape, there is, in some places, a mutual indentation of the different pieces of gravel into each other; an indentation which resembles perfectly that junction of the different bones of the _cranium_, called sutures, and which must have necessarily required a mixture of those bodies while in a soft or fluid state. this appearance of indentation is by no means singular, or limited to one particular specimen. i have several specimens of different marbles, in which fine examples of this species of mixture may be perceived. but in this particular case of the spanish pudding-stone, where the mutual indentation is made between two pieces of hard stone, worn round by attrition, the softening or fusion of these two bodies is not simply rendered probable, but demonstrated. having thus proved, that those strata had been consolidated by simple fusion, as proposed, we now proceed to show, that this mineral operation had been not only general, as being found in all the regions of the globe, but universal, in consolidating our earth in all the various degrees, from loose and incoherent shells and sand, to the most solid bodies of the siliceous and calcareous substances. to exemplify this in the various collections and mixtures of sands, gravels, shells, and corals, were endless and superfluous. i shall only take, for an example, one simple homogeneous body, in order to exhibit it in the various degrees of consolidation, from the state of simple incoherent earth to that of the most solid marble. it must be evident that this is chalk; naturally a soft calcareous earth, but which may be also found consolidated in every different degree. through the middle of the isle of wight, there runs a ridge of hills of indurated chalk. this ridge runs from the isle of wight directly west into dorsetshire, and goes by corscastle towards dorchester, perhaps beyond that place. the sea has broke through this ridge at the west end of the isle of wight, where columns of the indurated chalk remain, called the needles; the same appearance being found upon the opposite shore in dorsetshire. in this field of chalk, we find every gradation of that soft earthy substance to the most consolidated body of this indurated ridge, which is not solid marble, but which has lost its chalky property, and has acquired a kind of stony hardness. we want only further to see this cretaceous substance in its most indurated and consolidated state; and this we have in the north of ireland, not far from the giants causeway. i have examined cargoes of this lime-stone brought to the west of scotland, and find the most perfect evidence of this body having been once a mass of chalk, which is now a solid marble. thus, if it is by means of fusion that the strata of the earth have been, in many places, consolidated, we must conclude, that all the degrees of consolidation, which are indefinite, have been brought about by the same means. now, that all the strata of the mineral regions, which are those only now examined, have been consolidated in some degree, is a fact for which no proof can be offered here, but must be submitted to experience and inquiry; so far, however, as they shall be considered as consolidated in any degree, which they certainly are in general, we have investigated the means which had been employed in that mineral operation. we have now considered the concretions of particular bodies, and the general consolidation of strata; but it may be alleged, that there is a great part of the solid mass of this earth not properly comprehended among those bodies which have been thus proved to be consolidated by means of fusion. the body here alluded to is granite; a mass which is not generally stratified, and which, being a body perfectly solid, and forming some part in the structure of this earth, deserves to be considered. the nature of granite, as a part of the structure of the earth, is too intricate a subject to be here considered, where we only seek to prove the fusion of a substance from the evident marks which are to be observed in a body. we shall, therefore, only now consider one particular species of granite; and if this shall appear to have been in a fluid state of fusion, we may be allowed to extend this property to all the kind. the species now to be examined comes from the north country, about four or five miles west from portfoy, on the road to huntly. i have not been upon the spot, but am informed that this rock is immediately connected or continuous with the common granite of the country. this indeed appears in the specimens which i have got; for, in some of these, there is to be perceived a gradation from the regular to the irregular sort. this rock may indeed be considered, in some respects, as a porphyry; for it has an evident ground, which is feld-spar, in its sparry state; and it is, in one view, distinctly maculated with quartz, which is transparent, but somewhat dark-coloured[ ]. [note : plate ii. fig. . . .] considered as a porphyry, this specimen is no less singular than as a granite. for, instead of a siliceous ground, maculated with the rhombic feld-spar, which is the common state of porphyry, the ground is uniformly crystallised, or a homogeneous regular feld-spar, maculated with the transparent siliceous substance. but as, besides the feld-spar and quartz, which are the constituent parts of the stone, there is also mica, in some places, it may, with propriety, be termed a granite. the singularity of this specimen consists, not in the nature or proportions of its constituent parts, but in the uniformity of the sparry ground, and the regular shape of the quartz mixture. this siliceous substance, viewed in one direction, or longitudinally, may be considered as columnar, prismatical, or continued in lines running nearly parallel. these columnar bodies of quartz are beautifully impressed with a figure on the sides, where they are in contact with the spar. this figure is that of furrows or channels, which are perfectly parallel, and run across the longitudinal direction of the quartz. this is represented in fig. . this striated figure is only seen when, by fracture, the quartz is separated from the contiguous spar. but what i would here more particularly represent is, the transverse section of those longitudinal siliceous bodies these are seen in fig. . . and . they have not only separately the forms of certain typographic characters, but collectively give the regular lineal appearance of types set in writing. it is evident from the inspection of this fossil, that the sparry and siliceous substances had been mixed together in a fluid state; and that the crystallization of the sparry substance, which is rhombic, had determined the regular structure of the quartz, at least in some directions. thus, the siliceous substance is to be considered as included in the spar, and as figured, according to the laws of crystallization proper to the sparry ground; but the spar is also to be found included in the quartz. it is not, indeed, always perfectly included or inclosed on all sides; but this is sometimes the case, or it appears so in the section. fig. . . . . . and . are those cases magnified, and represent the different figured quartz inclosing the feld-spar. in one of them, the feld-spar, which is contained within the quartz, contains also a small triangle of quartz, which it incloses. now, it is not possible to conceive any other way in which those two substances, quartz and feld-spar, could be thus concreted, except by congelation from a fluid state, in which they had been mixed. there is one thing more to be observed with regard to this curious species of granite. it is the different order or arrangement of the crystallization or internal structure of the feld-spar ground, in two contiguous parts of the same mass. this is to be perceived in the polished surface of the stone, by means of the reflection of light. there is a certain direction in which, viewing the stone, when the light falls with a proper obliquity, we see a luminous reflection from the internal parts of the stone. this arises from the reflecting surfaces of the sparry structure or minute cracks, all turned in one direction, consequently, giving that luminous appearance only in one point of view. now, all the parts of the stone in which the figured quartz is directed in the same manner, or regularly placed in relation to each other, present that shining appearance to the eye at one time, or in the same point of direction. but there are parts of the mass, which, though immediately contiguous and properly continuous, have a different disposition of the figured quartz; and these two distinguished masses, in the same surface of the polished stone, give to the eye their shining appearance in very different directions. fig. . shows two of those figured and shining masses, in the same plane or polished surface. it must be evident, that, as the crystallization of the sparry structure is the figuring cause of the quartz bodies, there must be observed a certain correspondency between those two things, the alinement (if i may be allowed the expression) of the quartz, and the shining of the sparry ground. it must also appear, that at the time of congelation of the fluid spar, those two contiguous portions had been differently disposed in the crystallization of their substance. this is an observation which i have had frequent opportunities of making, with respect to masses of calcareous spar. upon the whole, therefore, whether we shall consider granite as a stratum or as an irregular mass, whether as a collection of several materials, or as the separation of substances which had been mixed, there is sufficient evidence of this body having been consolidated by means of fusion, and in no other manner. we are thus led to suppose, that the power of heat and operation of fusion must have been employed in consolidating strata of loose materials, which had been collected together and amassed at the bottom of the ocean. it will, therefore, be proper to consider, what are the appearances in consolidated strata that naturally should follow, on the one hand, from fluidity having been, in this manner, introduced by means of heat, and, on the other, from the interstices being filled by means of solution; that so we may compare appearances with the one and other of those two suppositions, in order to know that with which they may be only found consistent. the consolidation of strata with every different kind of substance was found to be inconsistent with the supposition, that aqueous solution had been the means employed for this purpose. this appearance, on the contrary, is perfectly consistent with the idea, that the fluidity of these bodies had been the effect of heat; for, whether we suppose the introduction of foreign matter into the porous mass of a stratum for its consolidation, or whether we shall suppose the materials of the mass acquiring a degree of softness, by means of which, together with an immense compression, the porous body might be rendered solid; the power of heat, as the cause of fluidity and vapour, is equally proper and perfectly competent. here, therefore, appearances are as decidedly in favour of the last supposition, as they had been inconsistent with the first. but if strata have been consolidated by means of aqueous solution, these masses should be found precisely in the same state as when they were originally deposited from the water. the perpendicular section of those masses might show the compression of the bodies included in them, or of which they are composed; but the horizontal section could not contain any separation of the parts of the stratum from one another. if, again, strata have been consolidated by means of heat, acting in such a manner as to soften their substance, then, in cooling, they must have formed rents or separations of their substance, by the unequal degrees of contraction which the contiguous strata may have suffered. here is a most decisive mark by which the present question must be determined. there is not in nature any appearance more distinct than this of the perpendicular fissures and separations in strata. these are generally known to workmen by the terms of veins or backs and cutters; and there is no consolidated stratum that wants these appearances. here is, therefore, a clear decision of the question, whether it has been by means of heat, or by means of aqueous solution, that collections of loose bodies at the bottom of the sea have been consolidated into the hardest rocks and most perfect marbles[ ]. [note : this subject is extremely interesting, both to the theory of the earth, and to the science cf the mining art; i will now illustrate that theory, with an authority which i received after giving this dissertation to the royal society. it is in the second volume of m. de saussure's _voyages dans les alpes_. here i find proper examples for illustrating that subject of mineralogy; and i am happy to have this opportunity of giving the reasoning of a man of science upon the subject, and the opinion of a person who is in every respect so well qualified to judge upon a point of this kind. the first example is of a marble in the alps, (_voyages dans les alpes._) tom. . page . "la pâte de ces brèches est tantôt blanche, tantôt grise, et les fragmens qui y font renfermés font, les uns blancs, les autres gris, d'autres roux, et presque toujours d'une couleur différente de celle de la pâte qui les lit. ils sont tous de nature calcaire; tels étaient au moins tous ceux que j'ai pus observer; et ce qu'il-y-a de remarquable, c'est qu'ils sont tous posés dans le sens des feuillets de la pierre; on diroit en les voyant, qu'ils ont tous été comprimés et écrasés dans le même sens. cette même pierre est mêlée de mica, sur-tout dans les interstices des couches et entre les fragmens et la pâte qui les réunit; mais on ne voit point de mica dans les fragmens eux-mêmes. on trouve aussi dans ces brèches des infiltrations de quartz. cette pierre est coupée par des fréquentes fissures perpendiculaires aux plans des couches. on voit clairement que ces fentes out été formées par l'inégal affaissement des couches, et non par une retraite spontanée: car les morceaux ou fragmens étrangers sont tous partagés et coupés net par ces fissures au lieu que dans les divisions naturelles des couches, ces mêmes fragmens sont entiers et saillans au dehors de la surface. les noeuds de quartz et les divers crystaux, que renferment les roches feuilletées, présentent le même phénomène, et l'on peut en tirer la même conséquence; ils font partagés dans les fentes, et entiers dans les séparations des couches." he finds those particular strata in the other side of the mountain _col de la seigne_, and gives us the following observations: "plus bas on passe entre deux bancs de ces mêmes brèches, entre lesquels sont interposées des couches d'ardoises noires et de grès feuilletés micacés, dont la situation est la même. "on retrouve encore ces brèches vers le has de la descente, au pied de pyramides calcaires dont j'ai parlé plus haut. je trouvai en de très-jolis crystaux de roche qui s'étaient formés dans les fentes de cette brèche. il y avoit même un mélange de quartz et de mica qui s'étoit moulé dans quelques-une de ces fentes. c'étoit donc une roche semblable aux primitives, et pourtant d'une formation postérieure à celle de la pierre calcaire. et quel système pourroit nous persuader que la nature ne puisse encore produire ce qu'elle a produit autrefois!" m. de saussure has here given us an example of a calcareous braccia, as he calls it, but which is rather a pudding stone, with veins or contractions of the mass. he does not seem to understand these as consequences of the consolidation of those strata; this, however, is the only light in which these appearances may be explained, when those bodies are thus divided without any other separation in the mass. the second example is found in the vertical strata of those mountains through which the rhône has made its way in running from the great valley of the _vallais_ towards the lake of geneva. (chapitre xlviii.) "c'est une espèce de pétrosilex gris, dur, sonore, un peu transparent, qui se débite en feuillets minces parfaitement plans et réguliers. ces feuillets, ou plutôt ces couches, courent à degrés du nord par est, en montant du coté de l'ouest sous un angle de degrés. ces couches sont coupées par des fentes qui leur sont à-peu-près perpendiculaires et qui le sont aussi à l'horizon. cette pierre s'emploie aux mêmes usage que l'ardoise, mais elle est beaucoup plus forte et plus durable, parce qu'elle est plus dure et moins accessible aux impressions de l'eau et de l'air. § . "ces pétrosilex feuilletés changent peu-à-peu de nature, en admettant dans les interstices de leurs feuillets des parties de feldspath. ils out alors l'apparence d'une roche feuilletée, quartzeuse et micacée, (_quartzum fornacum w._). mais cette apparence est trompeuse; car on n'y trouve pas un atome de quartz: toutes les parties blanches qui donnent du feu contre l'acier, font du feldspath; et les parties grise écailleuses ne font point du mica, ce sont de lames minces du pétrosilex dont j'ai déjà parlé." here is evidently what i would call petuntze strata, or porcelane stone, that is, strata formed by the deposits of such materials as might come from the _detritus_ of granite, arranged at the bottom of the sea, and consolidated by heat in the mineral regions. we have precisely such stratified masses in the pentland hills near edinburgh. i have also a specimen of the same kind, brought from the east indies, in which there is the print of an organized body. i believe it to be of some coralline or zoophite. § . "cette roche mélangée continue jusqu'à ce que le rocher s'éloigne un peu du grand chemin. là, ce rocher se présente coupé à pic dans une grande étendue, et divisé par de grandes fentes obliques, à-peu-près parallèles entr'elles. ces fentes partagent la montagne en grandes tranches de à pieds d'épaisseur, que de loin semblent être des couches. mais lorsqu'on s'en approche, on voit, par le tissu même de la pierre feuilletée, que ses vraies couches font avec l'horizon des angles de à degré, et que ces grandes divisions sont de vraies fentes par lesquelles un grand nombre de couches consécutives sont coupées presque perpendiculairement à leurs plans. les masses de rocher, comprises entre ces grandes fentes, sont encore divisées par d'autres fentes plus petites, dont la plupart sont paralleles aux grandes, d'autres leur sont obliques; mais toutes sont à très-peu-près perpendiculaires aux plans des couchés dont la montagne est composée." here is a distinct view of that which may be found to take place in all consolidated strata, whatever be the composition of the stratum; and it is this appearance which is here maintained to be a physical demonstration, that those strata had been consolidated by means of heat softening their materials. in that case, those stratified bodies, contracting in cooling, form veins and fissures traversing perpendicularly their planes; and these veins are afterwards filled with mineral substances. these are what i have here distinguished as the _particular_ veins of mineral masses; things perfectly different from proper mineral or metallic veins, which are more general, as belonging to immense masses of those strata; and which had been formed, not from the contraction, but from the disrupture of those masses, and by the forcible injection of fluid mineral substances from below. now these two species of veins, the particular and the general, although occasionally connected, must be in science carefully distinguished; in the one, we see the means which had been employed for the consolidation of the strata; in the other, we see that power by which the strata have been raised from the bottom of the sea and placed in the atmosphere.] error never can be consistent, nor can truth fail of having support from the accurate examination of every circumstance. it is not enough to have found appearances decisive of the question, with regard to the two suppositions which have been now considered, we may farther seek confirmation of that supposition which has been found alone consistent with appearances. if it be by means of heat and fusion that strata have been consolidated, then, in proportion to the degree of consolidation they have undergone from their original state, they should, _caeteris paribus_, abound more with separations in their mass. but this conclusion is found consistent with appearances. a stratum of porous sand-stone does not abound so much with veins and cutters as a similar stratum of marble, or even a similar stratum of sand-stone that is more consolidated. in proportion, therefore, as strata have been consolidated, they are in general intersected with veins and cutters; and in proportion as strata are deep in their perpendicular section, the veins are wide, and placed at greater distances. in like manner, when strata are thin, the veins are many, but proportionally narrow. it is thus, upon chemical principles, to be demonstrated, that all the solid strata of the globe have been condensed by means of heat, and hardened from a state of fusion. but this proposition is equally to be maintained from principles which are mechanical. the strata of the globe, besides being formed of earths, are composed of sand, of gravel, and fragments of hard bodies, all which may be considered as, in their nature, simple; but these strata are also found composed of bodies which are not simple, but are fragments of former strata, which had been consolidated, and afterwards were broken and worn by attrition, so as to be made gravel. strata composed in this manner have been again consolidated; and now the question is, by what means? if strata composed of such various bodies had been consolidated, by any manner of concretion, from the fluidity of a dissolution, the hard and solid bodies must be found in their entire state, while the interstices between those constituent parts of the stratum are filled up. no partial fracture can be conceived as introduced into the middle of a solid mass of hard matter, without having been communicated from the surrounding parts. but such partial separations are found in the middle of those hard and solid masses; therefore, this compound body must have been consolidated by other means than that of concretion from a state of a solution. the spanish marble already described, as well as many consolidated strata of siliceous gravel, of which i have specimens, afford the clearest evidence of this fact. these hard bodies are perfectly united together, in forming the most solid mass; the contiguous parts of some of the rounded fragments are interlaced together, as has already been observed; and there are partial shrinkings of the mass forming veins, traversing several fragments, but perfectly filled with the sparry substance of the mass, and sometimes with parts of the stone distinctly floating in the transparent body of spar. now, there is not, besides heat or fusion, any known power in nature by which these effects might be produced. but such effects are general to all consolidated masses, although not always so well illustrated in a cabinet specimen. thus we have discovered a truth that is confirmed by every appearance, so far as the nature of the subject now examined admits. we now return to the general operation, of forming continents of those materials which had been deposited at the bottom of the sea. section iii. investigation of the natural operations employed in the production of land above the surface of the sea. we seek to know that operation by means of which masses of loose materials, collected at the bottom of the sea, were raised above its surface, and transformed into solid land. we have found, that there is not in this globe (as a planet revolving in the solar system) any power or motion adapted to the purpose now in view; nor, were there such a power, could a mass of simply collected materials have continued any considerable time to resist the waves and currents natural to the sea, but must have been quickly carried away, and again deposited at the bottom of the ocean. but we have found, that there had been operations, natural to the bowels of this earth; by which those loose and unconnected materials have been cemented together, and consolidated into masses of great strength and hardness; those bodies are thus enabled to resist the force of waves and currents, and to preserve themselves, for a sufficient time, in their proper shape and place, as land above the general surface of the ocean. we now desire to know, how far those internal operations of the globe, by which solidity and stability are procured to the beds of loose materials, may have been also employed in raising up a continent of land, to remain above the surface of the sea. there is nothing so proper for the erection of land above the level of the ocean, as an expansive power of sufficient force, applied directly under materials in the bottom of the sea, under a mass that is proper for the formation of land when thus erected. the question is not, how such a power may be procured; such a power has probably been employed. if, therefore, such a power should be consistent with that which we found had actually been employed in preparing the erected mass; or, if such a power is to be reasonably concluded as accompanying those operations which we have found natural to the globe, and situated in the very place where this expansive power appears to be required, we should thus be led to perceive, in the natural operations of the globe, a power as efficacious for the elevation of what had been at the bottom of the sea into the place of land, as it is perfect for the preparation of those materials to serve the purpose of their elevation. in opposition to this conclusion, it will not be allowed to allege; that we are ignorant how such a power might be exerted under the bottom of the ocean; for, the present question is not, what had been the cause of heat, which has appeared to have been produced in that place, but if this power of heat, which has certainly been exerted at the bottom of the ocean for consolidating strata, had been employed also for another purpose, that is, for raising those strata into the place of land. we may, perhaps, account for the elevation of land, by the same cause with that of the consolidation of strata, already investigated, without explaining the means employed by nature in procuring the power of heat, or showing from what general source of action this particular power had been derived; but, by finding in subterranean heat a cause for any other change, besides the consolidation of porous or incoherent bodies, we shall generalise a fact, or extend our knowledge in the explanation of natural appearances. the power of heat for the expansion of bodies, is, so far as we know, unlimited; but, by the expansion of bodies placed under the strata at the bottom of the sea, the elevation of those strata may be effected; and the question now to be resolved regards the actual exertion of this power of expansion. how far it is to be concluded as having been employed in the production of this earth above the level of the sea. before attempting to resolve that question, it may be proper to observe, there has been exerted an extreme degree of heat below the strata formed at the bottom of the sea; and this is precisely the action of a power required for the elevation of those heated bodies into a higher place. therefore, if there is no other way in which we may conceive this event to have been brought about, consistent with the present state of things, or what actually appears, we shall have a right to conclude, that such had been the order of procedure in natural things, and that the strata formed at the bottom of the sea had been elevated, as well as consolidated, by means of subterraneous heat. the consolidation of strata by means of fusion or the power of heat, has been concluded from the examination of nature, and from finding, that the present state of things is inconsistent with any other supposition. now, again, we are considering the only power that may be conceived as capable of elevating strata from the bottom of the sea, and placing such a mass above the surface of the water. it is a truth unquestionable, that what had been originally at the bottom of the sea, is at present the highest of our land. in explaining this appearance, therefore, no other alternative is left, but either to suppose strata elevated by the power of heat above the level of the present sea, or the surface of the ocean reduced many miles below the height at which it had subsisted during the collection and induration of the land which we inhabit. now, if, on the one hand, we are to suppose no general power of subterraneous fire or heat, we leave to our theory no means for the retreat of the sea, or the lowering of its surface; if, on the other hand, we are to allow the general power of subterraneous heat, we cannot have much difficulty in supposing, either the surface of the sea to have subsided, or the bottom of the ocean, in certain parts, to have been raised by a subterranean power above the level of its surface, according as appearances shall be found to require the one or other of those conclusions. here, therefore, we are again remitted to the history of nature, in order to find matter of fact by which this question may be properly decided. if the present land had been discovered by the subsiding of the waters, there has not been a former land, from whence materials had been procured for the construction of the present, when at the bottom of the sea; for, there is no vestige remaining of that land, the whole land of the present earth having been formed evidently at the bottom of the sea. neither could the natural productions of the sea have been accumulated, in the shape in which we now find them, on the surface of this earth; for, how should the alps and andes have been formed within the sea from the natural productions of the water? consequently, this is a supposition inconsistent with every natural appearance. the supposition, therefore, of the subsidence of the former ocean, for the purpose of discovering the present land, is beset with more difficulty than the simple erection of the bottom of the former ocean; for, _first_, there is a place to provide for the retirement of the waters of the ocean; and, _ dly_, there is required a work of equal magnitude; this is, the swallowing up of that former continent, which had procured the materials of the present land. on the one hand, the subsiding of the surface of the ocean would but make the former land appear the higher; and, on the other, the sinking the body of the former land into the solid globe, so as to swallow up the greater part of the ocean after it, if not a natural impossibility, would be at least a superfluous exertion of the power of nature. such an operation as this would discover as little wisdom in the end elected, as in the means appropriated to that end; for, if the land be not wasted and worn away in the natural operations of the globe, why make such a convulsion in the world in order to renew the land? if, again, the land naturally decays, why employ so extraordinary a power, in order to hide a former continent of land, and puzzle man? let us now consider how far the other proposition, of strata being elevated by the power of heat above the level of the sea, may be confirmed from the examination of natural appearances. the strata formed at the bottom of the ocean are necessarily horizontal in their position, or nearly so, and continuous in their horizontal direction or extent. they may change, and gradually assume the nature of each other, so far as concerns the materials of which they are formed; but there cannot be any sudden change, fracture, or displacement, naturally in the body of a stratum. but, if these strata are cemented by the heat of fusion, and erected with an expansive power acting below, we may expect to find every species of fracture, dislocation, and contortion, in those bodies, and every degree of departure from a horizontal towards a vertical position. the strata of the globe are actually found in every possible position: for, from horizontal, they are frequently found vertical; from continuous, they are broken and separated in every possible direction; and, from a plane, they are bent and doubled. it is impossible that they could have originally been formed, by the known laws of nature, in their present state and position; and the power that has been necessarily required for their change, has not been inferior to that which might have been required for their elevation from the place in which they had been formed. in this cafe, natural appearances are not anomalous. they are, indeed, infinitely various, as they ought to be, according to the rule; but all those varieties in appearances conspire to prove one general truth, viz. that all which we see had been originally composed according to certain principles, established in the constitution of the terraqueous globe; and that those regular compositions had been afterwards greatly changed by the operations of another power, which had introduced apparent confusion among things first formed in order and by rule. it is concerning the operation of this second power that we are now inquiring; and here the apparent irregularity and disorder of the mineral regions are as instructive, with regard to what had been transacted in a former period of time, as the order and regularity of those same regions are conclusive, in relation to the place in which a former state of things had produced that which, in its changed state, we now perceive. we are now to conclude, that the land on which we dwell had been elevated from a lower situation by the same agent which had been employed in consolidating the strata, in giving them stability, and preparing them for the purpose of the living world. this agent is matter actuated by extreme heat, and expanded with amazing force. if this has been the case, it will be reasonable to expect, that some of the expanded matter might be found condensed in the bodies which have been heated by that igneous vapour; and that matter, foreign to the strata, may have been thus introduced into the fractures and separations of those indurated masses. we have but to open our eyes to be convinced of this truth. look into the sources of our mineral treasures; ask the miner, from whence has come the metal into his vein? not from the earth or air above,--not from the strata which the vein traverses; these do not contain one atom of the minerals now considered. there is but one place from whence these minerals may have come; this is the bowels of the earth, the place of power and expansion, the place from whence must have proceeded that intense heat by which loose materials have been consolidated into rocks, as well as that enormous force by which the regular strata have been broken and displaced. our attention is here peculiarly called upon, where we have the opportunity of examining those mineral bodies, which have immediately proceeded from the unknown region, that place of power and energy which we want to explore; for, if such is the system of the earth, that materials are first deposited at the bottom of the ocean, there to be prepared in a certain manner, in order to acquire solidity, and then to be elevated into the proper place of land, these mineral veins, which contain matter absolutely foreign to the surface of the earth, afford the most authentic information with regard to the operations which we want to understand. it is these veins which we are to consider as, in some measure, the continuation of that mineral region, which lies necessarily out of all possible reach of our examination. it is, therefore, peculiarly interesting to know the state in which things are to be found in this place, which may be considered as intermediate between the solid land, upon the one hand, and the unknown regions of the earth, upon the other. we are now to examine those mineral veins; and these may be considered, first, in relation to their form, independent of their substance or particular contents; and, secondly, in relation to the contained bodies, independent of their form. in examining consolidated strata, we remarked veins and cutters as a proof of the means by which those bodies had been consolidated. in that case, the formation of these veins is a regulated process, determined by the degree of fusion, and the circumstances of condensation or refrigeration. in respect of these, the mineral veins now to be examined are anomalous. they are; but we know not why or how. we see the effect; but, in that effect, we do not see the cause. we can say, negatively, that the cause of mineral veins is not that by which the veins and fissures of consolidated strata have been formed; consequently, that it is not the measured contraction and regulated condensation of the consolidated land which has formed those general mineral veins; however, veins, similar in many respects, have been formed by the cooperation of this cause. having thus taken a view of the evident distinction between the veins or contractions that are particular to the consolidated body in which they are found, and those more general veins which are not limited to that cause, we may now consider what is general in the subject, or what is universal in these effects of which we wish to investigate the cause. the event of highest generalization or universality, in the form of those mineral veins, is fracture and dislocation. it is not, like that of the veins of strata, simple separation and measured contraction; it is violent fracture and unlimited dislocation. in the one case, the forming cause is in the body which is separated; for, after the body had been actuated by heat, it is by the reaction of the proper matter of the body, that the chasm which constitutes the vein is formed. in the other case, again, the cause is extrinsic in relation to the body in which the chasm is formed. there has been the most violent fracture and divulsion; but the cause is still to seek; and it appears not in the vein; for it is not every fracture and dislocation of the solid body of our earth, in which minerals, or the proper substances of mineral veins, are found. we are now examining matter of fact, real effects, from whence we would investigate the nature of certain events which do not now appear. of these, two kinds occur; one which has relation to the hardness and solidity, or the natural constitution of the body; the other, to its shape or local situation. the first has been already considered; the last is now the subject of inquiry. but, in examining those natural appearances, we find two different kinds of veins; the one necessarily connected with the consolidating cause; the other with that cause of which we now particularly inquire. for, in those great mineral veins, violent fracture and dislocation is the principle; but there is no other principle upon which strata, or masses formed at the bottom of the sea, can be placed at a height above its surface. hence, in those two different operations, of forming mineral veins, and erecting strata from a lower to a higher place, the principle is the same; for, neither can be done without violent fracture and dislocation. we now only want to know, how far it is by the same power, as well as upon the same principle, that these two operations have been made. an expansive force, acting from below, is the power most proper for erecting masses; but whether it is a power of the same nature with that which has been employed in forming mineral veins, will best appear in knowing the nature of their contents. these, therefore, may be now considered. every species of fracture, and every degree of dislocation and contortion, may be perceived in the form of mineral veins; and there is no other general principle to be observed in examining their form. but, in examining their contents, some other principle may appear, so far as, to the dislocating power or force, there may be superadded matter, by which something in relation to the nature of the power may be known. if, for example, a tree or a rock shall be found simply split asunder, although there be no doubt with regard to some power having been applied in order to produce the effect, yet we are left merely to conjecture at the power. but when wedges of wood or iron, or frozen water, should be found lodged in the cleft, we might be enabled, from this appearance, to form a certain judgment with regard to the nature of the power which had been applied. this is the case with mineral veins. we find them containing matter, which indicates a cause; and every information in this case is interesting to the theory. the substances contained in mineral veins are precisely the same with those which, in the former section, we have considered as being made instrumental in the consolidation of strata; and they are found mixed and concreted in every manner possible. but, besides this evidence for the exertion of extreme heat, in that process by which those veins were filled, there is another important observation to be gathered from the inspection of this subject. there appears to have been a great mechanical power employed in the filling of these veins, as well as that necessarily required in making the first fracture and divulsion. this appears from the order of the contents, or filling of these veins, which is a thing often observed to be various and successive. but what it is chiefly now in view to illustrate, is that immense force which is manifested in the fracture and dispersion of the solid contents which had formerly filled those veins. here we find fragments of rock and spar floating in the body of a vein filled with metallic substances; there, again, we see the various fragments of metallic masses floating in the sparry and siliceous contents. one thing is demonstrable from the inspection of the veins and their contents; this is, the successive irruptions of those fluid substances breaking the solid bodies which they meet, and floating those fragments of the broken bodies in the vein. it is very common to see three successive series of those operations; and all this may be perceived in a small fragment of stone, which a man of science may examine in his closet, often better than descending to the mine, where all the examples are found on an enlarged scale. let us now consider what power would be required to force up, from the most unfathomable depth of the ocean, to the andes or the alps, a column of fluid metal and of stone. this power cannot be much less than that required to elevate the highest land upon the globe. whether, therefore, we shall consider the general veins as having been filled by mineral steams, or by fluid minerals, an elevating power of immense force is still required, in order to form as well as fill those veins. but such a power acting under the consolidated masses at the bottom of the sea, is the only natural means for making those masses land. if such have been the operations that are necessary for the production of this land; and if these operations are natural to the globe of this earth, as being the effect of wisdom in its contrivance, we shall have reason to look for the actual manifestation of this truth in the phaenomena of nature, or those appearances which more immediately discover the actual cause in the perceived effect. to see the evidence of marble, a body that is solid, having been formed of loose materials collected at the bottom of the sea, is not always easy, although it may be made abundantly plain; and to be convinced that this calcareous stone, which calcines so easily in our fires, should have been brought into fusion by subterraneous heat, without suffering calcination, must require a chain of reasoning which every one is not able to attain[ ]. but when fire bursts forth from the bottom of the sea, and when the land is heaved up and down, so as to demolish cities in an instant, and split asunder rocks and solid mountains, there is nobody but must see in this a power, which may be sufficient to accomplish every view of nature in erecting land, as it is situated in the place most advantageous for that purpose. [note : mr le chevalier de dolomieu, in considering the different effects of heat, has made the following observation; journal de physique, mai . "je dis _le feu tel que nous l'employons_ pour distinguer le feu naturel des volcans, du feu de nos fourneaux et de celui de nos chalumeaux. nous sommes obligés de donner une grande activité à son action pour suppléer et au volume qui ne seroit pas à notre disposition et au tems que nous sommes forcés de ménager, et cette manière d'appliquer une chaleur très-active, communique le mouvement et le désordre jusques dans les molécules constituantes. agrégation et composition, tout est troublé. dans les volcans la grand masse du feu supplée à son intensité, le tems remplace son activité, de manière qu'il tourmente moins les corps fournis à son action; il ménage leur composition en relâchant leur agrégation, et les pierres qui eut été rendues fluides par l'embrasement volcanique peuvent reprendre leur état primitif; la plupart des substances qu'un feu plus actif auroit expulsées y restent encore. voilà pourquoi les laves ressemblent tellement aux pierres naturelles des espèces analogues, qu'elles ne peuvent en être distinguées; voilà également pourquoi les verres volcaniques eux-même renferment encore des substances élastiques qui les font boursoufler lorsque nous les fondons de nouveau, et pourquoi ces verres blanchissent aussi, pour lors, par la dissipation, d'une substance grasse qui a résisté à la chaleur des volcans, et que volatilise la chaleur par laquelle nous obtenons leur second fusion." no doubt, the long application of heat may produce changes in bodies very different from those which are occasioned by the sudden application of a more intense heat; but still there must be sufficient intensity in that power, so as to cause fluidity, without which no chemical change can be produced in bodies. the essential difference, however, between the natural heat of the mineral regions, and that which we excite upon the surface of the earth, consists in this; that nature applies heat under circumstances which we are not able to imitate, that is, under such compression as shall prevent the decomposition of the constituent substances, by the separation of the more volatile from the more fixed parts. this is a circumstance which, so far as i know, no chemist or naturalist has hitherto considered; and it is that by which the operations of the mineral regions must certainly be explained. without attending to this great principle in the mineralizing operations of subterraneous fire, it is impossible to conceive the fusion and concretion of those various bodies, which we examine when brought up to the surface of the earth.] the only question, therefore, which it concerns us to decide at present, is, whether those operations of extreme heat, and violent mechanic force, be only in the system as a matter of accident; or if, on the contrary, they are operations natural to the globe, and necessary in the production of such land as this which we inhabit? the answer to this is plain: these operations of the globe remain at present with undiminished activity, or in the fullness of their power. a stream of melted lava flows from the sides of mount aetna. here is a column of weighty matter raised from a great depth below, to an immense height above, the level of the sea, and rocks of an enormous size are projected from its orifice some miles into the air. every one acknowledges that here is the liquefying power and expansive force of subterranean fire, or violent heat. but, that sicily itself had been raised from the bottom of the ocean, and that the marble called sicilian jasper, had its solidity upon the same principle with the lava, would stumble many a naturalist to acknowledge. nevertheless, i have in my possession a table of this marble, from which it is demonstrable, that this calcareous stone had flowed, and been in such a state of fusion and fluidity as lava. here is a comparison formed of two mineral substances, to which it is of the highest importance to attend. the solidity and present state of the one of these is commonly thought to be the operation of fire; of the other, again, it is thought to be that of water. this, however, is not the case. the immediate state and condition of both these bodies is now to be considered as equally the effect of fire or heat. the reason of our forming such a different judgment with regard to these two subjects is this; we see, in the one case, the more immediate connection of the cause and the effect, while, in the other, we have only the effects from whence we are in science to investigate the cause. but, if it were necessary always to see this immediate connection, in order to acknowledge the operation of a power which, at present, is extinguished in the effect, we should lose the benefit of science, or general principles, from whence particulars may be deduced, and we should be able to reason no better than the brute. man is made for science; he reasons from effects to causes, and from causes to effects; but he does not always reason without error. in reasoning, therefore, from appearances which are particular, care must be taken how we generalise; we should be cautious not to attribute to nature, laws which may perhaps be only of our own invention. the immediate question now before us is not, if the subterraneous fire, or elevating power, which we perceive sometimes as operating with such energy, be the consolidating cause of strata formed at the bottom of the sea; nor, if that power be the means of making land appear above the general surface of the water? for, though this be the end we want to arrive at ultimately, the question at present in agitation respects the laws of nature, or the generality of particular appearances. has the globe within it such an active power as fits it for the renovation of that part of its constitution which may be subject to decay? are those powerful operations of fire, or subterraneous heat, which so often have filled us with terror and astonishment, to be considered as having always been? are they to be concluded as proper to every part upon the globe, and as continual in the system of this earth? if these points in question shall be decided in the affirmative, we can be at no loss in ascertaining the power which has consolidated strata, nor in explaining the present situation of those bodies, which had their origin at the bottom of the sea. this, therefore, should be the object of our pursuit; and in order to have demonstration in a case of physical inquiry, we must again have recourse to the book of nature. the general tendency of heat is to produce fluidity and softness; as that of cold is, on the contrary, to harden soft and fluid bodies. but this softening power of heat is not uniform in its nature; it is made to act with very different effect, according to the nature of the substance to which it is applied. we are but limited in the art of increasing the heat or the cold of bodies; we find, however, extreme difference in their substances with respect to fusibility. a fusible substance, or mineral composition in a fluid state, is emitted from those places of the earth at which subterraneous fire and expansive force are manifested in those eruptive operations. in examining these emitted bodies, men of science find a character for such productions, in generalising the substance, and understanding the natural constitution of those bodies. it is in this manner that such a person, finding a piece of lava in any place of the earth, says with certainty, here is a stone which had congealed from a melted state. having thus found a distinguishing character for those fused substances called, in general, lavas, and having the most visible marks for that which had been actually a volcano, naturalists, in examining different countries, have discovered the most undoubted proofs of many ancient volcanos, which had not been before suspected. thus, volcanos will appear to be not a matter of accident, or as only happening in a particular place, they are general to the globe, so far as there is no place upon the earth that may not have an eruption of this kind; although it is by no means necessary for every place to have had those eruptions. volcanos are natural to the globe, as general operations; but we are not to consider nature as having a burning mountain for an end in her intention, or as a principal purpose in the general system of this world. the end of nature in placing an internal fire or power of heat, and a force of irresistible expansion, in the body of this earth, is to consolidate the sediment collected at the bottom of the sea, and to form thereof a mass of permanent land above the level of the ocean, for the purpose of maintaining plants and animals. the power appointed for this purpose is, as on all other occasions, where the operation is important, and where there is any danger of a shortcoming, wisely provided in abundance; and there are contrived means for disposing of the redundancy. these, in the present case, are our volcanos. a volcano is not made on purpose to frighten superstitious people into fits of piety and devotion, nor to overwhelm devoted cities with destruction; a volcano should be considered as a spiracle to the subterranean furnace, in order to prevent the unnecessary elevation of land, and fatal effects of earthquakes; and we may rest assured, that they, in general, wisely answer the end of their intention, without being in themselves an end, for which nature had exerted such amazing power and excellent contrivance. let us take a view of the most elevated places of the earth; if the present theory is just, it is there that we should find volcanos. but is not this the case? there are volcanos in the andes; and round the alps we find many volcanos, which are in france upon the one side, and in germany upon the other, as well as upon the italian side, where vesuvius still continues to exhibit violent eruptions. it is not meant to allege, that it is only upon the summit of a continent volcanos should appear. subterraneous fire has sometimes made its appearance in bursting from the bottom of the sea. but, even in this last case, land was raised from the bottom of the sea, before the eruption made its exit into the atmosphere. it must also be evident, that, in this case of the new island near santorini, had the expansive power been retained, instead of being discharged, much more land might have been raised above the level of the ocean. now, the eruption of that elastic force through the bottom of the sea, may be considered as a waste of power in the operations of the globe, where the elevation of indurated strata is an object in the exertion of that power; whereas, in the centre of a continent sufficiently elevated above the level of the sea, the eruption of that fiery vapour calculated to elevate the land, while it may occasionally destroy the habitations of a few, provides for the security and quiet possession of the many. in order to see the wisdom of this contrivance, let us consider the two extreme places at which this eruption of ignited matter may be performed. these are, on the one hand, within a continent of land, and, on the other, at the bottom of the ocean. in the one case, the free eruption of the expanding power should be permitted; because the purpose for which it had been calculated to exist has been accomplished. in the other, again, the free eruption of that powerful matter should be repressed; because there is reserved for that power much of another operation in that place. but, according to the wise constitution of things, this must necessarily happen. the eruption of the fiery vapour from volcanos on the continent or land, is interrupted only occasionally, by the melted bodies flowing in the subterraneous chimney; whereas, at the bottom of the ocean, the contact of the water necessarily tends to close the orifice, by accumulating condensed matter upon the weakest place. if this be a just theory of the natural operations of the globe, we shall have reason to expect, that great quantities of this melted matter, or fusible substance, may be found in form of lava, among the strata of the earth, where there are no visible marks of any volcano, or burning mountain, having existed. here, therefore, is an important point to be determined; for, if it shall appear that much of this melted matter, analogous to lava, has been forced to flow among the strata which had been formed at the bottom of the sea, and now are found forming dry land above its surface, it will be allowed, that we have discovered the secret operations of nature concocting future land, as well as those by which the present habitable earth had been produced from the bottom of the abyss. here, therefore, we shall at present rest the argument, with endeavouring to show that such is actually the case. it appears from cronstedt's mineralogy, that the rock-stone, called trap by the swedes, the amygdaloides and the schwarts-stein of the germans, are the same with the whin-stone of this country. this is also fully confirmed by specimens from sweden, sent me by my friend dr gahn. whatever, therefore, shall be ascertained with regard to our whin-stone, may be so far generalized or extended to the countries of norway, sweden, and germany. the whin-stone of scotland is also the same with the toad-stone of derbyshire, which is of the amygdaloides species; it is also the same with the flagstone of the south of staffordshire, which is a simple whin-stone, or perfect trap. england, therefore, must be included in this great space of land, the mineral operations of which we explore; and also ireland, of which the giant's causeway, and many others, are sufficient proof. in the south of scotland, there is a ridge of hills, which extends from the west side of the island in galloway to the east side in berwickshire, composed of granite, of schistus, and of siliceous strata. the grampians on the north, again, form another range of mountains of the same kind; and between these two great fields of broken, tumbled, and distorted strata, there lies a field of lesser hardness and consolidation, in general; but a field in which there is a great manifestation of subterraneous fire, and of exerted force. the strata in this space consist, in general, of sand-stone, coal, lime-stone or marble, iron-stone, and marl or argillaceous strata, with strata of analogous bodies, and the various compositions of these. but what is to the present purpose is this, that, through all this space, there are interspersed immense quantities of whinstone; a body which is to be distinguished as very different from lava; and now the disposition of this whin-stone is to be considered. sometimes it is found in an irregular mass or mountain, as mr cronstedt has properly observed; but he has also said, that this is not the case in general. his words are: "it is oftener found in form of veins in mountains of another kind, running commonly in a serpentine manner, contrary or across to the direction of the rock itself." the origin of this form, in which the trap or whin-stone appears, is most evident to inspection, when we consider that this solid body had been in a fluid state, and introduced, in that state, among strata, which preserved their proper form. the strata appear to have been broken, and the two correspondent parts of those strata are separated to admit the flowing mass of whin-stone. a fine example of this kind may be seen upon the south side of the earn, on the road to crief. it is twenty-four yards wide, stands perpendicular, and appears many feet above the surface of the ground. it runs from that eastward, and would seem to be the same with that which crosses the river tay, in forming campsy-lin above stanley, as a lesser one of the same kind does below it. i have seen it at lednoc upon the ammon, where it forms a cascade in that river, about five or six miles west of campsy-lin. it appears to run from the tay east through strathmore, so that it may be considered as having been traced for twenty or thirty miles, and westwards to drummond castle, perhaps much farther. two small veins of the same kind, only two or three feet wide, may be seen in the bed of the water of leith, traversing the horizontal strata, the one is above st bernard's well, the other immediately below it. but, more particularly, in the shire of ayr, to the north of irvine, there are to be seen upon the coast, between that and scarmorly, in the space of about twenty miles, more than twenty or thirty such dykes (as they are called) of whin-stone. some of them are of a great thickness; and, in some places, there is perceived a short one, running at right angles, and communicating with other two that run parallel. there is in this country, and in derbyshire[ ], another regular appearance of this stone, which cronstedt has not mentioned. in this case, the strata are not broken in order to have the whin-stone introduced, they are separated, and the whin-stone is interjected in form of strata, having various degrees of regularity, and being of different thickness. on the south side of edinburgh, i have seen, in little more than the space of a mile from east to west, nine or ten masses of whin-stone interjected among the strata. these masses of whin-stone are from three or four to an hundred feet thick, running parallel in planes inclined to the horizon, and forming with it an angle of about twenty or thirty degrees, as may be seen at all times in the hill of salisbury craggs. [note : see mr whitehurst's theory of the earth.] having thus described these masses, which have flowed by means of heat among the strata of the globe, strata which had been formed by subsidence at the bottom of the sea, it will now be proper to examine the difference that subsists between these subterraneous lavas, as they may be termed, and the analogous bodies which are proper lavas, in having issued out of a volcano.[ ] [note : the chevalier de dolomieu, in his accurate examination of aetna and the lipari islands, has very well observed the distinction of these two different species of lavas; but without seeming to know the principle upon which this essential difference depends. no bias of system, therefore, can here be supposed as perverting the chevalier's view, in taking those observations; and these are interesting to the present theory, as corresponding perfectly with the facts from whence it has been formed. it will be proper to give the account of these in his own words. la zéolite est très-commune dans certains laves de l'ethna; il seroit peut-être possible d'y en rencontrer des morceaux aussi gros que ceux que fournit l'isle de ferroé. quoique cette substance semble ici appartenir aux laves, je ne dirai cependant point que toutes les zéolites soient volcaniques, ou unies à des matières volcaniques; celles que l'on trouve en allemagne sont, dit-on, dans des circonstances différentes; mais je doit annoncer que je n'ai trouvé cette substance en sicile, que dans les seules laves qui évidemment ont coulé dans la mer, et qui out été recouvertes par ses eaux. la zéolite des laves n'est point une déjection volcanique, ni une production du feu, ni même un matière que les laves aient enveloppée lorsqu'elles étoient fluides; elle est le résultat d'une opération et d'une combinaison postérieure, auxquelles les eaux de la mer ont concouru. les laves qui n'ont pas été submergées, n'en contiennent jamais. j'ai trouvé ces observations si constantes, que par-tout où je rencontrois de la zéolite, j'étois sûr de trouver d'autres preuves de submersion, et partout où je voyois des laves recouvertes des dépôts de l'eau, j'étois sûr de trouver de la zéolite, et un de ces faits m'a toujours indiqué l'autre. je me suis servi avec succès de cette observation pour diriger mes recherches, et pour connoître l'antiquité des laves. _minéralogie de volcans, par m. faujas de saint-fond_. here would appear to be the distinction of subterraneous lava, in which zeolite and calcareous spar may be found, and that which has flowed from a volcano, in which neither of these are ever observed.] there can be no doubt that these two different species of bodies have had the same origin, and that they are composed of the same materials nearly; but from the different circumstances of their production, there is formed a character to these bodies, by which, they may be perfectly distinguished. the difference of those circumstances consists in this; the one has been emitted to the atmosphere in its fluid state the other only came to be exposed to the light in a long course of time, after it had congealed under the compression of an immense load of earth, and after certain operations, proper to the mineral regions, had been exercised upon the indurated mass. this is the cause of the difference between those erupted lavas, and our whin-stone, toad-stone, and the swedish trap, which may be termed subterraneous lava. the visible effects of those different operations may now be mentioned. in the erupted lavas, those substances which are subject to calcine and vitrify in our fires, suffer similar changes, when delivered from a compression which had rendered them fixed, though in an extremely heated state. thus, a lava in which there is much calcareous spar, when it comes to be exposed to the atmosphere, or delivered from the compressing force of its confinement, effervesces by the explosion of its fixed air; the calcareous earth, at the same time, vitrifies with the other substances. hence such violent ebullition in volcanos, and hence the emission of so much pumice-stone and ashes, which are of the same nature. in the body of our whin-stone, on the contrary, there is no mark of calcination or vitrification. we frequently find in it much calcareous spar, or the _terra calcarea aerata_, which had been in a melted state by heat, and had been crystallized by congelation into a sparry form. such is the _lapis amygdaloides_, and many of our whin-stone rocks, which contain pebbles crystallized and variously figured, both calcareous, siliceous, and of a mixture in which both these substances form distinct parts. the specimens of this kind, which i have from the whin-stone or porphyry rock of the calton-hill, exhibit every species of mineral operation, in forming jasper, figured agate, and marble; and they demonstrate, that this had been performed by heat or fusion. i do not mean to say, that this demonstration is direct; it is conditional, and proceeds upon the supposition, that the basaltic or porphyry rock, in which those specimens are found, is a body which had been in a melted state. now, this is a supposition for which i have abundance of evidence, were it required; but naturalists are now sufficiently disposed to admit that proposition; they even draw conclusions from this fact, which, i think, they are not sufficiently warranted in doing; that is, from this appearance, they infer the former existence of volcanos in those places. for my part, though i have made the most strict examination, i never saw any vestige of such an event. that there are, in other countries, evident marks of volcanos which have been long extinguished, is unquestionably true; but naturalists, imagining that there are no other marks of subterraneous fire and fusion, except in the production of a lava, attribute to a volcano, as a cause, these effects, which only indicate the exertion of that power which might have been the cause of a volcano. if the theory now given be just, a rock of marble is no less a mark of subterraneous fire and fusion, than that of the basaltes; and the flowing of basaltic streams among strata broken and displaced, affords the most satisfactory evidence of those operations by which the body of our land had been elevated above the surface of the sea; but it gives no proof that the eruptive force of mineral vapours had been discharged in a burning mountain. now, this discharge is essential in the proper idea of a volcano. besides this internal mark of an unerupted lava in the substance of the stone or body of the flowing mass, there are others which belong to it in common with all other mineral strata, consolidated by subterraneous fire, and changed from the place of their original formation; this is, the being broken and dislocated, and having veins of foreign matter formed in their separations and contractions. if these are mineral operations, proper to the lower regions of the earth, and exerted upon bodies under immense compression, such things will be sometimes found in the unerupted lavas, as well as in the contiguous bodies with which they are associated. if, on the contrary, these are operations proper to the surface of the earth, where the dissolving power of water and air take place, and where certain stalactical and ferruginous concretions are produced by these means; then, in erupted lavas, we should find mineral concretions, which concretions should be denied to bodies which had been consolidated at the bottom of the sea; that is to say, where, without the operation of subterraneous fire, no changes of that kind could have taken place, as has already been observed. but in the unerupted species of lava, that is to say, in our whin-stone, every species of mineral appearance is occasionally to be found. let those who have the opportunity to examine, say, what arc to be found in proper lavas, that is, those of the erupted kind. sir william hamilton informed me, when i showed him those mineral veins and spars in our whin-stone, that he had never observed the like, in lavas we have now formed some conclusions with regard to the nature and production of those parts of the land of this globe which we have had the means of examining perfectly; but; from the accounts of travellers, and from, the specimens which are brought to us from distant parts, we have reason to believe, that all the rest of the earth is of the same nature with that which has been now considered. the great masses of the earth are the same every where; and all the different species of earths, of rocks or stone, which have as yet appeared, are to be found in the little space of this our island. it is true, that there are peculiar productions in the mineral kingdom which are rare, as being found only in few places; but these things are merely accidental in relation to the land, for they belong in property to those parts of the mineral region which we never see. such are, the diamond of the east, the platina of the west, and the tin of cornwall, germany, and sumatra. gold and silver, though found in many countries, do not appear to be immediately necessary in the production of a habitable country. iron, again, is universal in the operations of the globe, and is found often in that profusion which equals its utility. between these two extremes, we find all other minerals, that is to say, here and there in moderate quantity, and apparently in some proportion to their use. but all these substances are to be considered as the vapours of the mineral regions, condensed occasionally in the crevices of the land; and it is only the rocks and strata (in which those mineral veins are found) that are now examined with regard to their original composition, at the bottom of the sea, as well as to that, operation by which those bodies had been indurated in their substance, and elevated from the place in which they had been formed. thus, we have sufficient reason to believe, that, in knowing the construction of the land in europe, we know the constitution of the land in every part of the globe. therefore, we may proceed to form general conclusions, from the knowledge of the mineral region, thus acquired in studying those parts which are seen. having thus found, _first_, that the consolidated and indurated masses of our strata had suffered the effects of violent heat and fusion; _ dly_, that those strata, which had been formed in a regular manner at the bottom of the sea, have been violently bended, broken, and removed from their original place and situation; and, _lastly_, having now found the most indubitable proof, that the melting, breaking, and removing power of subterraneous fire, has been actually exerted upon this land which we examine, we cannot hesitate in ascribing these operations as a cause to those effects which are exposed to our view. now, these may be considered as consisting in the solid state and present situation of those stratified bodies, originally formed by subsidence in the ocean; appearances which cannot, in reason, be ascribed to any other cause, and which, upon this principle, are perfectly explained. it is not meant to specify every particular in the means employed by nature for the elevation of our land. it is sufficient to have shown, that there is, in nature, means employed for the consolidating of strata, formed originally of loose and incoherent materials; and that those same means have also been employed in changing the place and situation of those strata. but how describe an operation which man cannot have any opportunity of perceiving? or how imagine that, for which, perhaps, there are not proper data to be found? we only know, that the land is raised by a power which has for principle subterraneous heat; but, how that land is preserved in its elevated station, is a subject in which we have not even the means to form conjecture; at least, we ought to be cautious how we indulge conjecture in a subject where no means occur for trying that which is but supposition. we now proceed, from the facts which have been properly established, to reason with regard to the duration of this globe, or the general view of its operations, as a living world, maintaining plants and animals. section iv. system of decay and renovation observed in the earth. philosophers observing an apparent disorder and confusion in the solid parts of this globe, have been led to conclude, that there formerly existed a more regular and uniform state, in the constitution of this earth; that there had happened some destructive change; and that the original structure of the earth had been broken and disturbed by some violent operation, whether natural, or from a super-natural cause. now, all these appearances, from which conclusions of this kind have been formed, find the most perfect explanation in the theory which we have been endeavouring to establish; for they are the facts from whence we have reasoned, in discovering the nature and constitution of this earth: therefore, there is no occasion for having recourse to any unnatural supposition of evil, to any destructive accident in nature, or to the agency of any preternatural cause, in explaining that which actually appears. it is necessary for a living or inhabited world, that this should consist of land and water. it is also necessary, that the land should be solid and stable, refilling, with great power, the violent efforts of the ocean; and, at the same time, that this solid land should be resolved by the influence of the sun and atmosphere, so as to decay, and thus become a soil for vegetation. but these general intentions are perfectly fulfilled in the constitution of our earth, which has been now investigated. this great body being formed of different mixed masses, having various degrees of hardness and solubility, proper soil for plants is supplied from the gradual resolution of the solid parts; fertility in those soils arises from the mixture of different elementary substances; and stability is procured to that vegetable world, by the induration of certain bodies, those rocks and stones, which protect the softer masses of clay and soil. in this manner, also, will easily be explained those natural appearances which diversify the surface of the earth for the use of plants and animals, and those objects which beautify the face of nature for the contemplation of mankind. such are, the distinctions of mountains and valleys, of lakes and rivers, of dry barren deserts and rich watered plains, of rocks which stand apparently unimpaired by the lapse of time, and sands which fluctuate with the winds and tides. all these are the effects of steady causes; each of these has its proper purpose in the system of the earth; and in that system is contained another, which is that of living growing bodies, and of animated beings. but, besides this, man, the intellectual being, has, in this subject of the mineral kingdom, the means of gratifying the desire of knowledge, a faculty by which he is distinguished from the animal, and by which he improves his mind in knowing causes. man is not satisfied, like the brute, in seeing things which are; he seeks to know how things have been, and what they are to be. it is with pleasure that he observes order and regularity in the works of nature, instead of being disgusted with disorder and confusion; and he is made happy from the appearance of wisdom and benevolence in the design, instead of being left to suspect in the author of nature, any of that imperfection which he finds in himself. let us now take a view of that system of mineral economy, in which may be perceived every mark of order and design, of provident wisdom and benevolence. we have been endeavouring to prove, that all the continents and islands of this globe had been raised above the surface of the ocean; we have also aimed at pointing out the cause of this translation of matter, as well as of the general solidity of that which is raised to our view; but however this theory shall be received, no person of observation can entertain a doubt, that all, or almost all we see of this earth, had been originally formed at the bottom of the sea. we have now another object in our view; this is to investigate the operations of the globe, at the time that the foundation of this land was laying in the waters of the ocean, and to trace the existence and the nature of things, before the present land appeared above the surface of the waters. we should thus acquire some knowledge of the system according to which this world is ruled, both in its preservation and production; and we might be thus enabled to judge, how far the mineral system of the world shall appear to be contrived with all the wisdom, which is so manifest in what are termed the animal and vegetable kingdoms. it must not be imagined that this undertaking is a thing unreasonable in its nature; or that it is a work necessarily beset with any unsurmountable difficulty; for, however imperfectly we may fulfill this end proposed, yet, so far as it is to natural causes that are to be ascribed the operations of former time, and so far as, from the present state of things, or knowledge of natural history, we have it in our power to reason from effect to cause, there are, in the constitution of the world, which we now examine, certain means to read the annals of a former earth. the object of inquiry being the operations of the globe, during the time that the present earth was forming at the bottom of the sea, we are now to take a very general view of nature, without descending into those particulars which so often occupy the speculations of naturalists, about the present state of things. we are not at present to enter into any discussion with regard to what are the primary and secondary mountains of the earth; we are not to consider what is the first, and what the last, in those things which now are seen; whatever is most ancient in the strata which we now examine, is supposed to be collecting at the bottom of the sea, during the period concerning which we are now to inquire. we have already considered those operations which had been necessary in forming our solid land, a body consisting of materials originally deposited at the bottom of the ocean; we are now to investigate the source from whence had come all those materials, from the collection of which the present land is formed; and from knowing the state in which those materials had existed, previously to their entering the composition of our strata, we shall learn something concerning the natural history of this world, while the present earth was forming in the sea. we have already observed, that all the strata of the earth are composed either from the calcareous relicts of sea animals, or from the collection of such materials as we find upon our shores. at a gross computation, there may perhaps be a fourth part of our solid land, which is composed from the matter that had belonged to those animals. now, what a multitude of living creatures, what a quantity of animal economy must have been required for producing a body of calcareous matter which is interspersed throughout all the land of the globe, and which certainly forms a very considerable part of that mass! therefore, in knowing how those animals had lived, or with what they had been fed, we shall have learned a most interesting part of the natural history of this earth; a part which it is necessary to have ascertained, in order to see the former operations of the globe, while preparing the materials of the present land. but, before entering upon this subject, let us examine the other materials of which our land is formed. gravel forms a part of those materials which compose our solid land; but gravel is no other than a collection of the fragments of solid stones worn round, or having their angular form destroyed by agitation in water, and the attrition upon each other, or upon similar hard bodies. consequently, in finding masses of gravel in the composition of our land, we must conclude, that there had existed a former land, on which there had been transacted certain operations of wind and water, similar to those which are natural to the globe at present, and by which new gravel is continually prepared, as well as old gravel consumed or diminished by attrition upon our shores. sand is the material which enters, perhaps in greatest quantity, the composition of our land. but sand, in general, is no other than small fragments of hard and solid bodies, worn or rounded more or less by attrition; consequently, the same natural history of the earth, which is investigated from the masses of gravel, is also applicable to those masses of sand which we find forming so large a portion of our present land throughout all the earth[ ]. [note : sand is a term that denotes no particular substance; although by it is commonly meant a siliceous substance, as being by far the most prevalent. sand is one of the modifications, of size and shape, in a hard body or solid substance, which may be infinitely diversified. the next modification to be distinguished in mineral bodies is that of gravel; and this differs in no respect from sand, except in point of size. next after gravel, in the order of ascent, come stones; and these bear nearly the same relation to gravel as gravel does to sand. now, by stones is to be understood the fragments of rocks or solid mineral bodies; and there is a perfect gradation from those stones to sand. i have already endeavoured to explain the formation of those stony substances; and now i am treating of a certain system of circulation, which is to be found among minerals. m. de luc censures me for not giving the origin of sand, of which i form the strata of the earth. he seems to have misunderstood my treatise. i do not pretend, as he does in his theory, to describe the beginning of things; i take things such as i find them at present, and from these i reason with regard to that which must have been. when, from a thing which is well known, we explain another which is less so, we then investigate nature; but when we imagine things without a pattern or example in nature, then, instead of natural history, we write only fable. m. de luc, in the letter already mentioned, says, "that sand may be, and i think it is, a substance which has formed _strata_ by _precipitation in a liquid_." this is but an opinion, which may be either true or false. if it be true, it is an operation of the mineral kingdom of which i am ignorant. in all the sand which i have ever examined, i have never seen any that might not be referred to the species of mineral substance from which it had been formed. when this author shall have given us any kind of information with regard to the production of sand _by precipitation in a liquid_, it will then be time enough to think of forming the strata of the earth with that sand.] clay is now to be considered as the last of those materials of which our strata are composed; but, in order to understand the nature of this ingredient, something must be premised. clay is a mixture of different earths or hard substances, in an impalpable state. those substances are chiefly the siliceous and aluminous earths. other earths are occasionally mixed in clays, or perhaps always to be found in some small portion. but this does not affect the general character of clay; it only forms a special variety in the subject. a sensible or considerable portion of calcareous earth, in the composition of clay, constitutes a marl, and a sufficient admixture of sand, a loam. an indefinite variety of those compositions of clay form a large portion of the present strata, all indurated and consolidated in various degrees; but this great quantity of siliceous, argillaceous, and other compound substances, in form of earth or impalpable sediment, corresponds perfectly with that quantity of those same substances which must have been prepared in the formation of so much gravel and sand, by the attrition of those bodies in the moving waters. therefore, from the consideration of those materials which compose the present land, we have reason to conclude, that, during the time this land was forming, by the collection of its materials at the bottom of the sea, there had been a former land containing materials similar to those which we find at present in examining the earth. we may also conclude, that there had been operations similar to those which we now find natural to the globe, and necessarily exerted in the actual formation of gravel, sand, and clay. but what we have now chiefly in view to illustrate is this, that there had then been in the ocean a system of animated beings, which propagated their species, and which have thus continued their several races to this day. in order to be convinced of that truth, we have but to examine the strata of our earth, in which we find the remains of animals. in this examination, we not only discover every genus of animal which at present exists in the sea, but probably every species, and perhaps some species with which at present we are not acquainted. there are, indeed, varieties in those species, compared with the present animals which we examine, but no greater varieties than may perhaps be found among the same species in the different quarters of the globe. therefore, the system of animal life, which had been maintained in the ancient sea, had not been different from that which now subsists, and of which it belongs to naturalists to know the history. it is the nature of animal life to be ultimately supported from matter of vegetable production. inflammable matter may be considered as the _pabulum_ of life. this is prepared in the bodies of living plants, particularly in their leaves exposed to the sun and light. this inflammable matter, on the contrary, is consumed in animal bodies, where it produces heat or light, or both. therefore, however animal matter, or the pabulum of life, may circulate through a series of digesting powers, it is constantly impaired or diminishing in the course of this economy, and, without the productive power of plants, it would finally be extinguished.[ ] [note : see dissertations on different subjects of natural philosophy, part ii.] the animals of the former world must have been sustained during indefinite successions of ages. the mean quantity of animal matter, therefore, must have been preserved by vegetable production, and the natural waste of inflammable substance repaired with continual addition; that is to say, the quantity of inflammable matter necessary to the animal consumption, must have been provided by means of vegetation. hence we must conclude, that there had been a world of plants, as well as an ocean replenished with living animals. we are now, in reasoning from principles, come to a point decisive of the question, and which will either confirm the theory, if it be just, or confute our reasoning, if we have erred. let us, therefore, open the book of nature, and read in her records, if there had been a world bearing plants, at the time when this present world was forming at the bottom of the sea. here the cabinets of the curious are to be examined; but here some caution is required, in order to distinguish things perfectly different, which sometimes are confounded. fossil wood, to naturalists in general, is wood dug up from under ground, without inquiring whether this had been the production of the present earth, or that which had preceded it in the circulation of land and water. the question is important, and the solution of it is, in general, easy. the vegetable productions of the present earth, however deep they may be found buried beneath its surface, and however ancient they may appear, compared with the records of our known times, are new, compared with the solid land on which they grew; and they are only covered with the produce of a vegetable soil, or the alluvion of the present land on which we dwell, and on which they had grown. but the fossil bodies which form the present subject of inquiry, belonged to former land, and are found only in the sea-born strata of our present earth. it is to these alone that we appeal, in order to prove the certainty of former events. mineralised wood, therefore, is the object now inquired after; that wood which had been lodged in the bottom of the sea, and there composed part of a stratum, which hitherto we have considered as only formed of the materials proper to the ocean. now, what a profusion of this species of fossil wood is to be found in the cabinets of collectors, and even in the hands of lapidaries, and such artificers of polished stones! in some places, it would seem to be as common as the agate. i shall only mention a specimen in my own collection. it is wood petrified with calcareous earth, and mineralised with pyrites. this specimen of wood contains in itself, even without the stratum of stone in which it is embedded, the most perfect record of its genealogy. it had been eaten or perforated by those sea worms which destroy the bottoms of our ships. there is the clearest evidence of this truth. therefore, this wood had grown upon land which flood above the level of sea, while the present land was only forming at the bottom of the ocean. wood is the most substantial part of plants, as shells are the more permanent part of marine animals. it is not, however, the woody part alone of the ancient vegetable world that is transmitted to us in the record of our mineral pages. we have the type of many species of foliage, and even of the most delicate flower; for, in this way, naturalists have determined, according to the linnaean system, the species, or at least the genus, of the plant. thus, the existence of a vegetable system at the period now in contemplation, so far from being doubtful, is a matter of physical demonstration. the profusion of this vegetable matter, delivered into the ocean, which then generated land, is also evidenced in the amazing quantities of mineral coal which is to be found in perhaps every region of the earth. nothing can be more certain, than that all the coaly or bituminous strata have had their origin from the substance of vegetable bodies that grew upon the land. those strata, tho', in general, perfectly consolidated, often separate horizontally in certain places; and there we find the fibrous or vascular structure of the vegetable bodies. consequently, there is no doubt of fossil coal being a substance of vegetable production, however animal substances also may have contributed in forming this collection of oleaginous or inflammable matter. having thus ascertained the state of a former earth, in which plants and animals had lived, as well as the gradual production of the present earth, composed from the materials of a former world, it must be evident, that here are two operations which are necessarily consecutive. the formation of the present earth necessarily involves the destruction of continents in the ancient world; and, by pursuing in our mind the natural operations of a former earth, we clearly see the origin of that land, by the fertility of which, we, and all the animated bodies of the sea, are fed. it is in like manner, that, contemplating the present operations of the globe, we may perceive the actual existence of those productive causes, which are now laying the foundation of land in the unfathomable regions of the sea, and which will, in time, give birth to future continents. but though, in generalising the operations of nature, we have arrived at those great events, which, at first sight, may fill the mind with wonder and with doubt, we are not to suppose, that there is any violent exertion of power, such as is required in order to produce a great event in little time; in nature, we find no deficiency in respect of time, nor any limitation with regard to power. but time is not made to flow in vain; nor does there ever appear the exertion of superfluous power, or the manifestation of design, not calculated in wisdom to effect some general end. the events now under consideration may be examined with a view to see this truth; for it may be inquired, why destroy one continent in order to erect another? the answer is plain; nature does not destroy a continent from having wearied of a subject which had given pleasure, or changed her purpose, whether for a better or a worse; neither does she erect a continent of land among the clouds, to show her power, or to amaze the vulgar man; nature has contrived the productions of vegetable bodies, and the sustenance of animal life, to depend upon the gradual but sure destruction of a continent; that is to say, these two operations necessarily go hand in hand. but with such wisdom has nature ordered things in the economy of this world, that the destruction of one continent is not brought about without the renovation of the earth in the production of another; and the animal and vegetable bodies, for which the world above the surface of the sea is leveled with its bottom, are among the means employed in those operations, as well as the sustenance of those living beings is the proper end in view. thus, in understanding the proper constitution of the present earth, we are led to know the source from whence had come all the materials which nature had employed in the construction of the world which appears; a world contrived in consummate wisdom for the growth and habitation of a great diversity of plants and animals; and a world peculiarly adapted to the purposes of man, who inhabits all its climates, who measures its extent, and determines its productions at his pleasure. the whole of a great object or event fills us with wonder and astonishment, when all the particulars, in the succession of which the whole had been produced, may be considered without the least emotion. when, for example, we behold the pyramids of egypt, our mind is agitated with a crowd of ideas that highly entertains the person who understands the subject; but the carrying a heavy stone up to the top of a hill or mountain would give that person little pleasure or concern. we wonder at the whole operation of the pyramid, but not at any one particular part. the raising up of a continent of land from the bottom of the sea, is an idea that is too great to be conceived easily in all the parts of its operations, many of which are perhaps unknown to us; and, without being properly understood, so great an idea may appear like a thing that is imaginary. in like manner, the co-relative, or corresponding operation, the destruction of the land, is an idea that does not easily enter into the mind of man in its totality, although he is daily witness to part of the operation. we never see a river in a flood, but we must acknowledge the carrying away of part of our land, to be sunk at the bottom of the sea; we never see a storm upon the coast, but we are informed of a hostile attack of the sea upon our country; attacks which must, in time, wear away the bulwarks of our soil, and sap the foundations of our dwellings. thus, great things are not understood without the analysing of many operations, and the combination of time with many events happening in succession. let us now consider what is to be the subject of examination, and where it is that we are to observe those operations which must determine either the stability or the instability of this land on which we live. our land has two extremities; the tops of the mountains, on the one hand, and the sea-shores, on the other: it is the intermediate space between these two, that forms the habitation of plants and animals. while there is a sea-shore and a higher ground there is that which is required in the system of the world: take these away, and there would remain an aqueous globe, in which the world would perish. but, in the natural operations of the world, the land is perishing continually; and this is that which now we want to understand. upon the one extremity of our land, there is no increase, or there is no accession of any mineral substance. that place is the mountain-top, on which nothing is observed but continual decay. the fragments of the mountain are removed in a gradual succession from the highest station to the lowest. being arrived at the shore, and having entered the dominion of the waves, in which they find perpetual agitation, these hard fragments, which had eluded the resolving powers natural to the surface of the earth, are incapable of resisting the powers here employed for the destruction of the land. by the attrition of one hard body upon another, the moving stones and rocky shore, are mutually impaired. and that solid mass, which of itself had potential liability against the violence of the waves, affords the instruments of its own destruction, and thus gives occasion to its actual instability. in order to understand the system of the heavens, it is necessary to connect together periods of measured time, and the distinguished places of revolving bodies. it is thus that system may be observed, or wisdom, in the proper adapting of powers to an intention. in like manner, we cannot understand the system of the globe, without seeing that progress of things which is brought about in time, thus measuring the natural operations of the earth with those of the heavens. this is properly the business of the present undertaking. our object is to know the time which had elapsed since the foundation of the present continent had been laid at the bottom of the ocean, to the present moment in which we speculate on these operations. the space is long; the data for the calculations are, perhaps, deficient: no matter; so far as we know our error, or the deficiency in our operation, we proceed in science, and shall conclude in reason. it is not given to man to know what things are truly in themselves, but only what those things are in his thought. we seek not to know the precise measure of any thing; we only understand the limits of a thing, in knowing what it is not, either on the one side or the other. we are investigating the age of the present earth, from the beginning of that body which was in the bottom of the sea, to the perfection of its nature, which we consider as in the moment of our existence; and we have necessarily another aera, which is collateral, or correspondent, in the progress of those natural events. this is the time required, in the natural operations of this globe, for the destruction of a former earth; an earth equally perfect with the present and an earth equally productive of growing plants and living animals. now, it must appear, that, if we had a measure for the one of those corresponding operations, we would have an equal knowledge of the other. the formation of a future earth being in the bottom of the ocean, at depths unfathomable to man, and in regions far beyond the reach of his observation, here is a part of the process which cannot be taken as a principle in forming an estimate of the whole. but, in the destruction of the present earth, we have a process that is performed within the limits of our observation; therefore, in knowing the measure of this operation, we shall find the means of calculating what had passed on a former occasion, as well as what will happen in the composition of a future earth. let us, therefore, now attempt to make this estimate of time and labour. the highest mountain may be levelled with the plain from whence it springs, without the loss of real territory in the land; but when the ocean makes encroachment on the basis of our earth, the mountain, unsupported, tumbles with its weight; and with the accession of hard bodies, moveable with the agitation of the waves, gives to the sea the power of undermining farther and farther into the solid basis of our land. this is the operation which is to be measured; this is the mean proportional by which we are to estimate the age of worlds that have terminated, and the duration of those that are but beginning. but how shall we measure the decrease of our land? every revolution of the globe wears away some part of some rock upon some coast; but the quantity of that decrease, in that measured time, is not a measurable thing. instead of a revolution of the globe, let us take an age. the age of man does no more in this estimate than a single year. he sees, that the natural course of things is to wear away the coast, with the attrition of the sand and stones upon the shore; but he cannot find a measure for this quantity which shall correspond to time, in order to form an estimate of the rate of this decrease. but man is not confined to what he sees; he has the experience of former men. let us then go to the romans and the greeks in search of a measure of our coasts, which we may compare with the present state of things. here, again, we are disappointed; their descriptions of the shores of greece and of italy, and their works upon the coast, either give no measure of a decrease, or are not accurate enough for such a purpose. it is in vain to attempt to measure a quantity which escapes our notice, and which history cannot ascertain; and we might just as well attempt to measure the distance of the stars without a parallax, as to calculate the destruction of the solid land without a measure corresponding to the whole. the description which polybius has given of the pontus euxinus, with the two opposite bosphori, the meotis, the propontis, and the port of byzantium, are as applicable to the present state of things as they were at the writing of that history. the filling up of the bed of the meotis, an event which, to polybius, appeared not far off, must also be considered as removed to a very distant period, though the causes still continue to operate as before. but there is a thing in which history and the present state of things do not agree. it is upon the coast of spain, where polybius says there was an island in the mouth of the harbour of new carthage. at present, in place of the island, there is only a rock under the surface of the water. it must be evident, however, that the loss of this small island affords no proper ground of calculation for the measure or rate of wasting which could correspond to the coast in general; as neither the quantity of what is now lost had been measured, nor its quality ascertained. let us examine places much more exposed to the fury of the waves and currents than the coast of carthagena, the narrow fretum, for example, between italy and sicily. it does not appear, that this passage is sensibly wider than when the romans first had known it. the isthmus of corinth is also apparently the same at present as it had been two or three thousand years ago. scilla and charibdis remain now, as they had been in ancient times, rocks hazardous for coasting vessels which had to pass that strait. it is not meant by this to say, these rocks have not been wasted by the sea, and worn by the attrition of moving bodies, during that space of time; were this true, and that those rocks, the bulwarks of the land upon those coasts, had not been at all impaired from that period, they might remain for ever, and thus the system of interchanging the place of sea and land upon this globe might be frustrated. it is only meant to affirm, that the quantity which those rocks, or that coast, have diminished from the period of our history, has either been too small a thing for human observation, or, which is more probable, that no accurate measurement of the subject, by which this quantity of decrease might have been ascertained, had been taken and recorded. it must be also evident, that a very small operation of an earthquake would be sufficient to render every means of information, in this manner of mensuration, unsatisfactory or precarious. pliny says italy was distant from sicily a mile and a half; but we cannot suppose that this measure was taken any otherwise than by computation, and such a measure is but little calculated to afford us the just means of a comparison with the present distance. he also says, indeed, that sicily had been once joined with italy. his words are: "quondam brutio agro cohaerens, mox interfuso mari avulsa.[ ]" but all that we can conclude from this history of pliny is, that, in all times, to people considering the appearances of those two approached coasts, it had seemed probable, that the sea formed a passage between the two countries which had been once united; in like manner as is still more immediately perceived, in that smaller disjunction which is made between the island of anglesey and the continent of wales. [note : lib. . cap. .] the port of syracuse, with the island which forms the greater and lesser, and the fountain of arethusa, the water of which the ancients divided from the sea with a wall, do not seem to be altered. from sicily to the coast of egypt, there is an uninterrupted course of sea for a thousand miles; consequently, the wind, in such a stretch of sea, should bring powerful waves against those coasts: but, on this coast of egypt, we find the rock on which was formerly built the famous tower of pharos; and also, at the eastern extremity of the port eunoste, the sea-bath, cut in the solid rock upon the shore. both those rocks, buffeted immediately with the waves of the mediterranean sea, are, to all appearance, the same at this day as they were in ancient times.[ ] [note : lettres sur l'egypte, m. savary.] many other such proofs will certainly occur, where the different parts of those coasts are examined by people of observation and intelligence. but it is enough for our present purpose, that this decrease of the coasts in general has not been observed; and that it is as generally thought, that the land is gaining upon the sea, as that the sea is gaining upon the land. to sum up the argument, we are certain, that all the coasts of the present continents are wasted by the sea, and constantly wearing away upon the whole; but this operation is so extremely slow, that we cannot find a measure of the quantity in order to form an estimate: therefore, the present continents of the earth, which we consider as in a state of perfection, would, in the natural operations of the globe, require a time indefinite for their destruction. but, in order to produce the present continents, the destruction of a former vegetable world was necessary; consequently, the production of our present continents must have required a time which is indefinite. in like manner, if the former continents were of the same nature as the present, it must have required another space of time, which also is indefinite, before they had come to their perfection as a vegetable world. we have been representing the system of this earth as proceeding with a certain regularity, which is not perhaps in nature, but which is necessary for our clear conception of the system of nature. the system of nature is certainly in rule, although we may not know every circumstance of its regulation. we are under a necessity, therefore, of making regular suppositions, in order to come at certain conclusions which may be compared with the present state of things. it is not necessary that the present land should be worn away and wasted, exactly in proportion as new land shall appear; or, conversely, that an equal proportion of new land should always be produced as the old is made to disappear. it is only required, that at all times, there should be a just proportion of land and water upon the surface of the globe, for the purpose of a habitable world. neither is it required in the actual system of this earth, that every part of the land should be dissolved in its structure, and worn away by attrition, so as to be floated in the sea. parts of the land may often sink in a body below the level of the sea, and parts again may be restored, without waiting for the general circulation of land and water, which proceeds with all the certainty of nature, but which advances with an imperceptible progression. many of such apparent irregularities may appear without the least infringement on the general system. that system is comprehended in the preparation of future land at the bottom of the ocean, from those materials which the dissolution and attrition of the present land may have provided, and from those which the natural operations of the sea afford. in thus accomplishing a certain end, we are not to limit nature with the uniformity of an equable progression, although it be necessary in our computations to proceed upon equalities. thus also, in the use of means, we are not to prescribe to nature those alone which we think suitable for the purpose, in our narrow view. it is our business to learn of nature (that is by observation) the ways and means, which in her wisdom are adopted; and we are to imagine these only in order to find means for further information, and to increase our knowledge from the examination of things which actually have been. it is in this manner, that intention may be found in nature; but this intention is not to be supposed, or vainly imagined, from what we may conceive to be. we have been now supposing, that the beginning of our present earth had been laid in the bottom of the ocean, at the completion of the former land; but this was only for the sake of distinctness. the just view is this, that when the former land of the globe had been complete, so as to begin to waste and be impaired by the encroachment of the sea, the present land began to appear above the surface of the ocean. in this manner we suppose a due proportion to be always preserved of land and water upon the surface of the globe, for the purpose of a habitable world, such as this which we possess. we thus, also, allow time and opportunity for the translation of animals and plants to occupy the earth. but, if the earth on which we live, began to appear in the ocean at the time when the last began to be resolved, it could not be from the materials of the continent immediately preceding this which we examine, that the present earth had been constructed; for the bottom of the ocean must have been filled with materials before land could be made to appear above its surface. let us suppose that the continent, which is to succeed our land, is at present beginning to appear above the water in the middle of the pacific ocean, it must be evident, that the materials of this great body, which is formed and ready to be brought forth, must have been collected from the destruction of an earth, which does not now appear. consequently, in this true statement of the case, there is necessarily required the destruction of an animal and vegetable earth prior to the former land; and the materials of that earth which is first in our account, must have been collected at the bottom of the ocean, and begun to be concocted for the production of the present earth, when the land immediately preceding the present had arrived at its full extent. this, however, alters nothing with regard to the nature of those operations of the globe. the system is still the same. it only protracts the indefinite space of time in its existence, while it gives us a view of another distinct period of the living world; that is to say, the world which we inhabit is composed of the materials, not of the earth which was the immediate predecessor of the present, but of the earth which, in ascending from the present, we consider as the third, and which had preceded the land that was above the surface of the sea, while our present land was yet beneath the water of the ocean. here are three distinct successive periods of existence, and each of these is, in our measurement of time, a thing of indefinite duration. we have now got to the end of our reasoning; we have no data further to conclude immediately from that which actually is: but we have got enough; we have the satisfaction to find, that in nature there is wisdom, system, and consistency. for having, in the natural history of this earth, seen a succession of worlds, we may from this conclude that there is a system in nature; in like manner as, from seeing revolutions of the planets, it is concluded, that there is a system by which they are intended to continue those revolutions. but if the succession of worlds is established in the system of nature, it is in vain to look for any thing higher in the origin of the earth. the result, therefore, of this physical inquiry is, that we find no vestige of a beginning,--no prospect of an end. chapter ii. an examination of mr kirwan's objections to the igneous origin of stony substances. a theory which is founded on a new principle, a theory which has to make its way in the public mind by overturning the opinions commonly received by philosophising men, and one which has nothing to recommend it but the truth of its principles, and the view of wisdom or design to which it leads, neither of which may perhaps be perceived by the generality of people, such a theory, i say, must meet with the strongest opposition from the prejudices of the learned, and from the superstition of those who judge not for themselves in forming their notions, but look up to men of science for authority. such is the case with some part of the theory of the earth, which i have given, and which will probably give offence to naturalists who have espoused an opposite opinion. in order, then, to obtain the approbation of the public, it may not be enough to give a theory that should be true, or altogether unexceptionable it may be necessary to defend every point that shall be thought exceptionable by other theorists, and to show the fallacy of every learned objection that may be made against it. it is thus, in general, that truth and error are forced to struggle together, in the progress of science; and it is only in proportion as science removes erroneous conceptions, which are necessarily in the constitution of human knowledge, that truth will find itself established in natural philosophy. mr kirwan has written a dissertation, entitled, _examination of the supposed igneous origin of stony substances_, which was read in the royal irish academy. the object of that dissertation is to state certain objections, which have occurred to him, against the theory of the earth published in the transactions of the edinburgh royal society; and he has attacked that theory in all the points where it appears to him to be vulnerable. it is to these objections that i am now to give an answer. the authority given to this dissertation, by the royal irish academy, as well as the reputation of the author, make it necessary for me to endeavour to put in their true light the facts alleged in that performance, and to analyse the arguments employed, in order to judge of the reasoning by which the theory of mineral fusion is refuted in this examination. a theory founded on truth, and formed according to the proper rules of science, can ever suffer from a strict examination, by which it would be but the more and more confirmed. but, where causes are to be traced through a chain of various complicated effects, an examination not properly conducted upon accurate analytical principles, instead of giving light upon a subject in which there had been obscurity and doubt, may only serve to perplex the understanding, and bring confusion into a subject which was before sufficiently distinct. to redress that evil, then, must require more labour and some address; and this is an inconveniency that may be looked for, more or less, in every controversial discussion. i do not mean to enter any farther into the defence of my theory in this chapter, than what is necessary to answer a man of science and respectability, who has stated his objections. the observations which he has made appear to me to be founded on nothing more than common prejudice, and misconceived notions of the subject. i am therefore to point out that erroneous train of reasoning, into which a hasty superficial view of things, perhaps, has led the patron of an opposite opinion to see my theory in an unfavourable light. this, however, is not all; for, that train of inconsequential reasoning is so congenial with the crude and inconsiderate notion generally entertained, of solid mineral bodies having been formed by the infiltration of water into the earth, that no opportunity should be lost of exposing an erroneous manner of reasoning, which is employed in supporting a hypothesis founded upon certain operations of the surface of this earth that cannot be properly applied to the formation of mineral bodies. this object, therefore, so far as it may come in the way, will be attended to in this discussion, although i shall have another opportunity of farther enlarging upon that subject. our author begins by examining a geological operation, the very opposite to that of mineral consolidation, and which would seem to have little connection with the subject of this dissertation. in my theory, i advanced two propositions with regard to the economy of this world: first, that the solid masses of this earth, when exposed to the atmosphere, decay, and are resolved into loose materials, of which the vegetable soil upon the surface is in part composed; and, secondly, that these loose materials are washed away by the currents of water, and thus carried at last into the sea. our author says "here are two suppositions, neither of which is grounded on facts;" and yet he has but the moment before made the following confession: "that the soil, however, receives an increase from some species of stones that moulder by exposition to the air cannot be denied, but there is no proof that all soil has arisen from decomposition."--surely _all soil_, that is made from the _hard and compact_ body of the land, which is my proposition, must have arisen from _decomposition_; and i have no where said, that _all_ the soil of this earth is made from the decomposition or detritus of those stony substances; for, masses of looser sand and softer substances contribute still more to the formation of vegetable soils. with regard to the other proposition, our author says, "soil is not constantly carried away by the water, even from mountains."--i have not said that it is _constantly_ washed away; for, while it is soil in which plants grow, it is not travelling to the sea, although it be on the road, and must there arrive in time. i have said, that it is _necessarily_ washed away, that is, occasionally. m. de luc's authority is then referred to, as refuting this operation of water and time upon the soil. now, i cannot help here observing, that our author seems to have as much misapprehended m. de luc's argument as he has done mine. that philosopher, in his letters to the queen, has described most accurately the decay of the rocks and solid mountains of the alps and jura, and the travelling of their materials by water, although he does not carry them to the sea. it is true, indeed, that this author, who supposes the present earth on which we dwell very young, is anxious to make an earth, _in time_, that shall not decay nor be washed away at all; but that time is not come yet; therefore the authority, here given against my theory, is the speculative supposition, or mere opinion, of a natural philosopher, with regard to an event which may never come to pass, and which i shall have occasion to consider fully in another place. our author had just now said, that i have advanced two suppositions, _neither of which is grounded on facts_: now, with regard to the one, he has acknowledged, that the mouldering of stones takes place, which is the fact on which that proposition is grounded; and with regard to the other, the only authority given against it is founded expressly upon the moving of soil by means of the rain water, in order to make sloping plains of mountains. here, therefore, i have grounded my propositions upon facts; and our author has founded his objections, first, upon a difficulty which he has himself removed; and, secondly, upon nothing but a visionary opinion, with regard to an earth which is not yet made, and which, when once made, is never more to change. after making some unimportant observations,--of all water not flowing into the sea,--and of the travelled materials being also deposited upon the plains, etc. our author thus proceeds: "hence the conclusion of our author relative to the imperfect constitution of the globe falls to the ground; and the pains he takes to learn, _by what means a decayed world may be renovated_, are superfluous."--the object of my theory is to show, that this decaying nature of the solid earth is the very _perfection_ of its constitution, as a living world; therefore, it was most proper that i should _take pains to learn_ by what means the decayed parts might be renovated. it is true, indeed, that this will be superfluous, when once that constitution of the earth, which m. de luc thinks is preparing, shall be finished; but, in the mean time, while rivers carry the materials of our land, and while the sea impairs the coast, i may be allowed to suppose that this is the actual constitution of the earth. i cannot help here animadverting upon what seems to be our author's plan, in making these objections, which have nothing to do with his examination. he accuses me of giving this world a false or imperfect constitution, (in which the solid land is considered as resolvable, and the materials of that land as being washed away into the sea,) for no other reason, that i can see, but because this may imply the formation of a future earth, which he is not disposed to allow; and, he is now to deny the stratified construction of this present earth to have been made by the deposits of materials at the bottom of the sea, because that would prove the existence of a former earth, which is repugnant to his notion of the origin of things, and is contrary, as he says, to reason, and the tenor of the mosaic history. let me observe, in passing, that m. de luc, of whose opinions our author expresses much approbation, thinks that he proves, from the express words and tenor of the mosaic history, that the present earth was at the bottom of the sea not many years ago, and that the former earth had then disappeared. but, what does our author propose to himself, in refusing to admit my view of the operations which are daily transacting upon the surface of this earth, where there is nothing dark or in the least mysterious, as there may be in the mineral regions? does he mean to say, that it is not the purpose of this world to provide soil for plants to grow in? does he suppose that this soil is not moveable with the running water of the surface? and, does he think that it is not necessary to replace that soil which is removed? this is all that i required in that constitution of the world which he has thus attacked; and i wish that he or any person would point out, in what respect i had demanded any thing unreasonable, or any thing that is not actually to be observed every day. thus i have endeavoured to show, that our author has attacked my theory in a part where i believe it must be thought invulnerable; but this is only, i presume, in order that he may make an attack with more advantage upon another part, viz. the composition of strata from the materials of an earth thus worn out in the service of vegetation,--materials which are necessarily removed in order to make way for that change of things in which consists the active and living system of this world. if he succeed in this attempt to refute my theory of the original formation of strata, he would then doubtless find it more easy to persuade philosophers that the means which i employ in bringing those materials again to light, when transformed into such solid masses as the system of this earth requires, are extravagant, unnatural, and unnecessary. let us then see how he sets about this undertaking. with regard to the composition of the earth, it is quoted from my theory, that _the solid parts of the globe are in general composed of sand, gravel, argillaceous and calcareous strata, or of various compositions of these with other substances_; our author then adds, "this certainly cannot be affirmed as a fact, but rather the contrary; it holds only true of the surface, the basis of the greater part of scotland is evidently a granitic rock, to say nothing of the continents, both of the old and new world, according to the testimony of all mineralogists." this proposition, with regard to the general composition of the earth, i have certainly not assumed, i have maintained it as a fact, after the most scrupulous examination of all that, with the most diligent search, i have been able to see, and of all that authors have wrote intelligibly upon the subject. if, therefore, i have so misrepresented this great geological fact on which my theory is absolutely founded, i must have erred with open eyes; and my theory of the earth, like others which have gone before it, will, upon close examination, appear to be unfounded, as the dissertation now before us is endeavouring to represent it. our author here, i think, alleges that the contrary to this, my fundamental proposition, is the truth; and he has given us scotland as an example in which his assertion (founded upon the testimony of all mineralogists), is illustrated. now my geological proposition should certainly be applicable to scotland, which is the country that i ought to be best acquainted with; consequently, if what our author here asserts be true, i would have deserved that blame which he is willing to throw on me. let me then beg the readers attention for a moment, that i may justify myself from that charge, and place in its proper light this authority, upon so material a point in geology. i had examined scotland from the one end to the other before i saw one stone of granite in its native place, i have moreover examined almost all england and wales, (excepting devonshire and cornwall) without seeing more of granite than one spot, not many hundred yards of extent; this is at chap; and i know, from information, that there is another small spot in the middle of england where it is just seen. but, let me be more particular with regard to scotland, the example given in proof. i had travelled every road from the borders of northumberland and westmoreland to edinburgh; from edinburgh, i had travelled to port-patrick, and from that along the coast of galloway and airshire to inverary in argyleshire, and i had examined every spot between the grampians and the tweedale mountains from sea to sea, without seeing granite in its place. i had also travelled from edinburgh by grief, rannock, dalwhiny, fort augustus, inverness, through east ross and caithness, to the pentland-frith or orkney islands, without seeing one block of granite in its place. it is true, i met with it on my return by the east coast, when i just saw it, and no more, at peterhead and aberdeen; but that was all the granite i had ever seen when i wrote my theory of the earth. i have, since that time, seen it in different places; because i went on purpose to examine it, as i shall have occasion to describe in the course of this work. i may now with some confidence affirm, from my own observation, and from good information with regard to those places where i have not been, except the northwest corner, i may affirm, i say, that instead of the basis of the greatest part of scotland being a granitic rock, which our author has maintained as an evident thing, there is very little of it that is so; not perhaps one five hundred part. so far also as i am to judge from my knowledge of the mineral construction of england and wales, which i have examined with the greatest care, and from the mineral chart which my friend mr watt made for me from his knowledge of cornwall, i would say that there is scarcely one five hundred part of britain that has granite for its basis. all the rest, except the porphyry and basaltes, consists of stratified bodies, which are composed more or less of the materials which i mentioned, generally, in the above quotation, and which our author would dispute. but do not let me take the advantage of this error of our author with regard to the mineralogy of scotland, and thus draw what may be thought an undue conclusion in favour of my general theory; let us go over and examine the continent of europe, and see if it is any otherwise there than in britain. from the granite of the ural mountains, to that which we find in the pyrenees, there is no reason, so far as i have been able to learn, to conclude that things are formed either upon any other principle, or upon a different scale. but, instead of one five hundred part, let us suppose there to be one fiftieth part of the earth in general resting upon granite, i could not have expressed myself otherwise than i have done; for, when i maintained that the earth in general consisted of stratified bodies, i said that this was only _nine tenths, or perhaps ninety-nine hundredths_ of the whole, and i mentioned that there were other masses of a different origin, which should be considered separately. our author, on the contrary, asserts that the old and new worlds, as well as scotland, are placed upon granite as a basis, which he says is according to the testimony of all mineralogists. i shall have occasion to examine this opinion of mineralogists, in comparing it with those masses of granite which appear to us; and i hope fully to refute the geological, as well as mineralogical notions with regard to that body. in the mean time, let me make the following reflection, which here naturally occurs. my theory of the earth is here examined,--not with the system of nature, or actual state of things, to which it certainly should have corresponded,--but with the systematic views of a person, who has formed his notions of geology from the vague opinion of others, and not from what he has seen. had the question been, how far my theory agreed with other theories, our author might very properly have informed his readers that it was diametrically opposite to the opinions of mineralogists; but, this was no reason for concluding it to be erroneous; on the contrary, it is rather a presumption that i may have corrected the error of mineralogists who have gone before me, in like manner as it is most reasonable to presume that our author may have corrected mine. let us then proceed to examine how far this shall appear to be the case. our author has stated very fairly from the theory, viz. _that all the strata of the earth, not only those consisting of calcareous masses, but others superincumbent on these, have had their origin at the bottom of the sea, by the collection of sand, gravel, shells, coralline, and crustaceous bodies, and of earths and clays variously mixed, separated, and accumulated._ he then adds, "various geological observations contradict this conclusion. there are many stratified mountains of argillaceous slate, gneiss, serpentine, jasper, and even marble, in which either sand, gravel, shells, coralline, or crustaceous bodies are never, or scarce ever found." here our author seems to have deceived himself, by taking a very partial view of things which should be fully examined, and well understood, before general conclusions are to be drawn from those appearances; for, although those particular objects may not be visible in the strata which he has enumerated, or many others, they are found in those strata which are either immediately connected and alternated with them, or with similar strata; something to that purpose i think i have said; and, if i had not, it certainly requires no deep penetration to have seen this clear solution of that appearance of those objects not being found in every particular stratum. he says that those marks of known materials are never or scarce ever found;--by _scarce ever_ he surely means that they are sometimes found; but if they shall only _once_ be found, his argument is lost. i have not drawn my geological conclusion from every particle in strata being distinguishable, but from there being certain distinguishable particles in strata, and from our knowing what had been the former state and circumstances of those distinguished parts. if every stone or part of a stratum, in which those known objects are not immediately visible, must be considered as so _many geological observations that contradict my theory_, (of strata being formed from the materials of a former earth), then, surely every stone and every stratum which visibly contains any of those materials, must prove my theory. but if every stratum, where these are found in any part of it, is to be concluded as having had its origin at the bottom of the sea; and, if every concomitant stratum, though not having those objects visible or sufficiently distinct, must be considered as having had the same or a similar origin, that pretended contradiction of my theory comes to no more than this, that every individual stone does not bear in it the same or equal evidence of that general proposition which necessarily results from the attentive consideration of the whole, including every part. but to see how necessary it is to judge in this manner, not partially, but upon the whole, we may observe, that there are two ways by which the visible materials or distinguishable bodies of a former earth, not only _may_ be rendered invisible in the composition of our present earth, but _must_ be so upon many occasions. these are, _first_, by mechanical comminution, which necessarily happens, more or less, in that operation by which bodies are moved against one another, and thus transported from the land to the bottom of the deepest seas; _secondly_, by chemical operations, (whatever these may be, whether the action of water or of fire, or both), which are also necessarily employed for consolidating those loose materials, that are to form the rocks and stones of this earth, and by means of which those materials are to have their distinguishable shapes affected in all degrees and obliterated. therefore, to demand the visible appearance of those materials in every stratum of the earth, or in every part of a stratum, is no other than to misunderstand the subject altogether. the geological observations, which have been thus alleged as contradicting my theory, are stratified bodies, containing proofs of the general origin which i attribute to the earth, but proofs which may not always be seen with equal facility as those which even convince the vulgar. our author has surely perplexed himself with what writers of late have said concerning primitive mountains as they are called, a subject of deeper search, than is commonly imagined, as i hope to show in the course of this work. it is an interesting subject of investigation, as giving us the actual view of those operations of nature which, in forming my theory of the earth, more general principles had led me to conclude _might be_. but, it is a subject which, i am afraid, will lead me to give farther offence to our author, however innocent i may be in giving nothing but what i have from nature. the reason for saying so is this; i am blamed for having endeavoured to trace back the operations of this world to a remote period, by the examination of that which actually appears, contrary, as is alleged, "to reason, and the tenor of the mosaic history, thus leading to an abyss, from which human reason recoils, etc." in a word, (says our author), "to make use of his own expression, _we find no vestige of a beginning._ then this system of successive worlds must have been eternal." such is the logic by which, i suppose, i am to be accused of atheism. our author might have added, that i have also said--_we see no prospect of an end_; but what has all this to do with the idea of eternity? are we, with our ideas of _time_, (or mere succession), to measure that of eternity, which never succeeded any thing, and which will never be succeeded? are we thus to measure eternity, that boundless thought, with those physical notions of ours which necessarily limit both space and time? and, because we see not the beginning of created things, are we to conclude that those things which we see have always been, or been without a cause? our author would thus, inadvertently indeed, lead himself into that gulf of irreligion and absurdity into which, he alleges, i have _boldly plunged_. in examining this present earth, we find that it must have had its origin at the bottom of the sea, although our author seems willing to deny that proposition. farther, in examining the internal construction of this stratified and sea-born mass, we find that it had been composed of the moved materials of a former earth; and, from the most accurate and extensive examination of those materials, which in many places are indeed much disguised, we are led necessarily to conclude, that there had been a world existing, and containing an animal, a vegetable, and a mineral system. but, in thus tracing back the natural operations which have succeeded each other, and mark to us the course of time past, we come to a period in which we cannot see any farther. this, however, is not the beginning of those operations which proceed in time and according to the wise economy of this world; nor is it the establishing of that, which, in the course of time, had no beginning; it is only the limit of our retrospective view of those operations which have come to pass in time, and have been conducted by supreme intelligence. my principal anxiety was to show how the constitution of this world had been wisely contrived; and this i endeavoured to do, not from supposition or conjecture, but from its answering so effectually the end of its intention, viz. the preserving of animal life, which we cannot doubt of being its purpose. here then is a world that is not eternal, but which has been the effect of wisdom or design. with regard again to the prospective view of the creation, how are we to see the end of that wise system of things which so properly fulfils the benevolent intention of its maker,--in giving sustenance to the animal part, and information to intellectual beings, who, in these works of nature, read what much concerns their peace of mind,--their intellectual happiness? what then does our author mean, in condemning that comprehensive view which i have endeavoured to take of nature? would he deny that there is to be perceived wisdom in the system of this world, or that a philosopher, who looks into the operations of nature, may not plainly read the power and wisdom of the creator, without recoiling, as he says, from the abyss? the abyss, from which a man of science should recoil, is that of ignorance and error. i have thus shown, that, from not perceiving the wise disposition of things upon the surface of this earth for the preservation of vegetable bodies, our author has been led to deny the necessary waste of the present earth, and the consequent preparation of materials for the construction of another; i have also shown, that he denies the origin which i had attributed to the stratified parts of this earth, as having been the collection of moving materials from a former earth; and now i am come to consider the professed purpose of this paper, viz. the examination of solid stony substances which we find in those strata of our earth, as well as in more irregular masses. here, no doubt, my theory would have been attacked with greater success, had our author succeeded in pointing out its error with regard to the original composition of those indurated bodies, to which i ascribe fusion as the cause of their solidity. for, if we should, according to our author's proposition, consider those consolidated bodies as having been originally formed in that solid state, here the door might be shut against any farther investigation;--but to what purpose?--surely not to refute my theory, but to explode every physical inquiry farther on the subject, and thus to lead us back into the science of darkness and of scepticism. but let us proceed to see our author's sentiments on this subject. as i had proved from matter of fact, or the actual appearances of nature, that all the strata of the earth had been formed at the bottom of the sea, by the subsidence of those materials which either come from the decaying land, or are formed in the sea itself, it was necessary that i should consider in what manner those spongy or porous bodies of loose materials, gathered together at the bottom of the sea, could have acquired that consolidated state in which we find them, now that they are brought up to our examination. upon this occasion, our author says, "the particles which now form the solid parts of the globe need not be supposed to have originally been either spongy or porous, the interior parts at the depth of a few miles might have been originally, as at present, a solid mass." if, indeed, we shall make that supposition, we may then save ourselves the trouble of considering either how the strata of the earth have been formed or consolidated; for, they might have been so originally. but, how can a naturalist who had ever seen a piece of derbyshire marble, or any other shell limestone, make that supposition? here are, to the satisfaction of every body of common understanding who looks at them, bodies which are perfectly consolidated, bodies which have evidently been formed at the bottom of the sea, and therefore which were not originally a solid mass. mr bertrand, it is true, wrote a book to prove that those appearances were nothing but a _lusus naturae_; and, i suppose he meant, with our author, that those strata had been also originally, as at present, a solid mass. with regard to the consolidation of strata, that cardinal point for discussion, our author gives the following answer: "abstracting from his own gratuitous hypothesis, it is very easy to satisfy our author on this head; the concreting and consolidating power in most cases arises from the mutual attraction of the component particles of stones to each other." this is an answer with regard to the _concreting power_, a subject about which we certainly are not here inquiring. our author, indeed, has mentioned a _consolidating power_; but that is an improper expression; we are here inquiring, how the interstices, between the collected materials of strata, deposited at the bottom of the sea, have been filled with a hard substance, instead of the fluid water which had originally occupied those spaces. our author then continues; "if these particles leave any interstices, these are filled with water, which no ways obstructs their solidity when the points of contact are numerous; hence the decrepitation of many species of stones when heated." if i understand our author's argument, the particles of stone are, by their mutual attractions, to leave those hard and solid bodies which compose the strata, that is to say, those hard bodies are to dissolve themselves; but, to what purpose? this must be to fill up the interstices, which we must suppose occupied by the water. in that case, we should find the original interstices filled with the substances which had composed the strata, and we should find the water translated into the places of those bodies; here would be properly a transmutation, but no consolidation of the strata, such as we are here to look for, and such as we actually find among those strata. it may be very easy for our author to form those explanations of natural phenomena; it costs no tedious observation of facts, which are to be gathered with labour, patience, and attention; he has but to look into his own fancy, as philosophers did in former times, when they saw the abhorrence of a vacuum and explained the pump. it is thus that we are here told the consolidation of strata _arises from the mutual attraction of the component particles of stones to each other_; the power, by which the particles of solid stony bodies retain their places in relation to each other, and resist separation from the mass, may, no doubt, be properly enough termed their mutual attractions; but we are not here inquiring after that power; we are to investigate the power by which the particles of hard and stony bodies had been separated, contrary to their mutual attractions, in order to form new concretions, by being again brought within the spheres of action in which their mutual attractions might take place, and make them one solid body. now, to say that this is by their mutual attraction, is either to misunderstand the proper question, or to give a most preposterous answer. it is not every one who is fit to reason with regard to abstract general propositions; i will now, therefore, state a particular case, in illustration of that proposition which has been here so improperly answered. the strata of derbyshire marbles were originally immense collections at the bottom of the sea, of calcareous bodies consisting almost wholly of various fragments of the _entrochi_; and they were then covered with an indefinite number of other strata under which these _entrochi_ must have been buried. in this original state of those strata, i suppose the interstices between the fragments of the coralline bodies to have been left full of sea-water; at present we find those interstices completely filled with a most perfectly solid body of marble; and the question is, whether that consolidating operation has been the work of water and solution, by our naturalist's termed infiltration; or if it has been performed, as i have maintained, by the softening power or heat, or introduction of matter in the fluid state of fusion. our author does not propose any other method for the consolidation of those loose and incoherent bodies, but he speaks of the _mutual attraction of the component particles of stone to each other_; will that fill the interstices between the coralline bodies with solid marble, as well as consolidate the coralline bodies themselves? or, if it should, how are those interstices to be thus filled with a substance perfectly different from the deposited bodies, which is also frequently the case? but, how reason with a person who, with this consolidation of strata, confounds the well known operation by which the mortar, made with caustic lime and sand, becomes a hard body! one would imagine that he were writing to people of the last age, and not to chemical philosophers who know so well how that mortar is concreted. to my argument, that these porous strata are found _consolidated with every different species of mineral substance_, our author makes the following observation: "here the difficulties to the supposition of an aqueous solution are placed in the strongest light; yet it must be owned that they partly arise from the author's own gratuitous supposition, that strata existed at the bottom of the sea previous to their consolidation;"--gratuitous supposition!--so far from being a supposition of any kind, it is a self evident proposition; the terms necessarily imply the conclusion. i beg the readers attention for a moment to this part of our author's animadversion, before proceeding to consider the whole; for, this is a point so essential in my theory, that if it be a gratuitous supposition, as is here asserted, it would certainly be in vain to attempt to build upon it the system of a world. that strata may exist, whether at the bottom of the sea, or any other where, without being consolidated, will hardly be disputed; for, they are actually found consolidated in every different degree. but, when strata are found consolidated, at what time is it that we are to suppose this event to have taken place, or this accident to have happened to them?--strata are formed at the bottom of water, by the subsidence or successive deposits of certain materials; it could not therefore be during their formation that such strata had been consolidated; consequently, we must necessarily _conclude_, without any degree of _supposition_, that _strata had existed at the bottom of the sea previous to their consolidation_, unless our author can show how they may have been consolidated previous to their existing. this then is what our author has termed a gratuitous supposition of mine, and which, he adds, "is a circumstance which will not be allowed by the patrons of the aqueous origin of stony substances, as we have already seen."--i am perfectly at a loss to guess at what is here alluded to _by having been already seen_, unless it be that which i have already quoted, concerning things which have been never seen, that is, _those interior parts of the earth which were originally a solid mass_.--i have hardly patience to answer such reasoning;--a reasoning which is not founded upon any principle, which holds up nothing but chimera to our view, and which ends in nothing that is intelligible;--but, others, perhaps, may see this dissertation of our author's in a different light; therefore, it is my duty to analyse the argument, however insignificant it may seem to me. i have minutely examined all the stratified bodies which i have been able, during a lifetime, to procure, both in this country of britain, and from all the quarters of the globe; and the result of my inquiry has been to conclude, that there is nothing among them in an original state, as the reader will see in the preceding chapter. with regard again to the masses which are not stratified, i have also given proof that they are not in their original state, such as granite, porphyry, serpentine, and basaltes; and i shall give farther satisfaction, i hope, upon that head, in the course of this work. i have therefore concluded, that there is nothing to be found in an original state, so far as we see, in the construction of this earth. but, our author answers, that the interior parts _might have been in an original state of solidity_.--so might they have been upon the surface of the earth, or on the summits of our mountains; but, we are not inquiring what they _might have been_, but what they truly _are_. it is from this actual state in which the solid parts of the earth are found, that i have endeavoured to trace back the different states in which they must have been; and, by generalising facts, i have formed a theory of the earth. if this be a wrong principle or manner of proceeding in a physical investigation, or if, proceeding upon that principle, i have made the induction by reasoning improperly on any occasion, let this be corrected by philosophers, who may reason more accurately upon the subject. but to oppose a physical investigation with this proposition, _that things might have been otherwise_, is to proceed upon a very different principle,--a principle which, instead of tending to bring light out of darkness, is only calculated to extinguish that light which we may have acquired. i shall afterwards have occasion to examine how far the philosophers, who attribute to aqueous solution the origin of stony substances, have proceeded in the same inductive manner of reasoning from effect to cause, as they ought to do in physical subjects, and not by feigning causes, or following a false analogy; in the mean time, i am to answer the objections which have been made to the theory of the earth. in opposition to the theory of consolidating bodies by fusion, our author has taken great pains to show, that i cannot provide materials for such a fire as would be necessary, nor find the means to make it burn had i those materials. had our author read attentively my theory he would have observed, that i give myself little or no trouble about that fire, or take no charge with regard to the procuring of that power, as i have not founded my theory on the _supposition_ of subterraneous fire, however that fire properly follows as a conclusion from those appearances on which the theory is founded. my theory is founded upon the general appearances of mineral bodies, and upon this, that mineral bodies must necessarily have been in a state of fusion. i do not pretend to prove, demonstratively, that they had been even hot, however that conclusion also naturally follows from their having been in fusion. it is sufficient for me to demonstrate, that those bodies must have been, more or less, in a state of softness and fluidity, without any species of solution. i do not say that this fluidity had been without heat; but, if that had been the case, it would have answered equally well the purpose of my theory, so far as this went to explain the consolidation of strata or mineral bodies, which, i still repeat, must have been by simple fluidity, and not by any species of solution, or any other solvent than that universal one which permeates all bodies, and which makes them fluid. our author has justly remarked the difficulty of fire burning below the earth and sea. it is not my purpose here to endeavour to remove those difficulties, which perhaps only exist in those suppositions which are made on this occasion; my purpose is to show, that he had no immediate concern with that question, in discussing the subject of the consolidation which we actually find in the strata of the earth, unless my theory, with regard to the igneous origin of stony substances, had proceeded upon the supposition of a subterraneous fire. it is surely one thing to employ fire and heat to melt mineral bodies, in supposing this to be the cause of their consolidation, and another thing to acknowledge fire or heat as having been exerted upon mineral bodies, when it is clearly proved, from actual appearances, that those bodies had been in a melted state, or that of simple fluidity. here are distinctions which would be thrown away upon the vulgar; but, to a man of science, who analyses arguments, and reasons strictly from effect to cause, this is, i believe, the proper way of coming at the truth. if the patrons of the aqueous origin of stony substances can give us any manner of scientifical, _i.e._ intelligible investigation of that process, it shall be attended to with the most rigid impartiality, even by a patron of the igneous origin of those substances, as he wishes above all things to distinguish, in the mineral operations, those which, on the one hand, had been the effect of water, from those which, on the other hand, had been the immediate effect of fire or fusion;--this has been my greatest study. but, while mineralists or geologists give us only mere opinions, what is science profited by such inconsequential observations, as are founded upon nothing but our vulgar notions? is the figure of the earth, _e.g._ to be doubted, because, according to the common notion of mankind, the existence of an antipod is certainly to be denied? i am not avoiding to meet that question with regard to the providing of materials for such a mineral fire as may be required; no question i desire more to be asked to resolve; but it must not be in the manner that our author has put that question. he has included this supposed difficulty among a string of other arguments by which he would refute my theory with regard to the igneous origin of stony substances, as if i had made that fire a necessary condition or a principle in forming my theory of consolidation. now, it is precisely the reverse; and this is what i beg that mineral philosophers will particularly attend to, and not give themselves so much unnecessary trouble, and me so disagreeable a talk. i have proved that those stony substances have been in the fluid state of fusion; and from this, i have inferred the former existence of an internal heat, a subterraneous fire, or a certain cause of fusion by whatever name it shall be called, and by whatever means it shall have been procured. the nature of that operation by which strata had been consolidated, like that by which they had been composed, must, according to my philosophy, be decided by ocular demonstration; from examining the internal evidence which is to be found in those bodies as we see them in the earth; because the consolidating operation is not performed in our sight, no more than their stratification which our author has also denied to have been made, as i have said, by the deposits of materials at the bottom of the sea. now, with regard to the means of procuring subterraneous fire, if the consolidating operation shall be thus decided to have been that of fusion, as i think i have fully shown, and for which i have as many witnesses, perhaps as there are mineral bodies, then our author's question, (how i am to procure a fire) in the way that he has put it, as an argument against the fusion, would be at least useless; for, though i should here confess my ignorance with regard to the means of procuring fire, the evidence of the melting operation, or former fluidity of those mineral bodies, would not be thereby in the least diminished. if again no such evidence for the fusion of those bodies shall appear, and it be concluded that they had been consolidated by the action of water alone, as our author seems inclined to maintain, he would have no occasion to start difficulties about the procuring of fire, in order to refute a theory which then would fall of itself as having no foundation. but in order to see this author's notion of the theory which he is here examining, it may be proper to give a specimen of his reasoning upon this subject of heat. he says, "that my supposition of heat necessary for consolidating strata is _gratuitous_, not only because it is unnecessary, as we have already shown, but also because it is inconsistent with our author's own theory." let us now consider those two propositions. _first_, it is unnecessary, _as we have already shown_;--i have already taken particular notice of what we have been shown on this occasion, viz. that the earth at a certain depth _may have been originally in a solid state_; and, that, where it is to be consolidated, this is done by the _mutual attraction of the stony particles_. here is all that we have been shown to make subterraneous heat, for the consolidation of strata, unnecessary; and now i humbly submit, if this is sufficient evidence, that mineral heat is a gratuitous supposition. secondly, "_it is inconsistent with our author's own theory._" here i would beg the readers attention to the reasoning employed on this occasion. he says, "according to him these strata, which were consolidated by heat, were composed of materials gradually worn from a preceding continent, casually and successively deposited in the sea; where then will he find, and how will he suppose, to have been formed those enormous masses of sulphur, coal, or bitumen, necessary to produce that immense heat necessary for the fusion of those vast mountains of stone now existing? all the coal, sulphur, and bitumen, now known, does not form the , part of the materials deposited within one quarter of a mile under the surface of the earth; if, therefore, they were, as his hypothesis demands, carried off and mixed with the other materials, and not formed in vast and separate collections, they could never occasion, by their combustion, a heat capable of producing the smallest effect, much less those gigantic effects which he requires." here is a comparative estimate formed between two things which have not any necessary relation; these are, the quantity of combustible materials found in the earth, on the one hand, and the quantity which is supposed necessary for hardening and consolidating strata, on the other. if this earth has been consolidated by the burning of combustible materials, there must have been a superfluity, so far as there is a certain quantity of these actually found unconsumed in the strata of the earth. our author's conclusion is the very opposite; let us then see how he is to form his argument, by which he proves that the supposition of subterraneous heat for hardening bodies is gratuitous and unnecessary, as being inconsistent with my theory. according to my theory, the strata of this earth are composed of the materials which came from a former earth; particularly these combustible strata that contain plants which must have grown upon the land. let us then suppose the subterraneous fire supplied with its combustible materials from this source, the vegetable bodies growing upon the surface of the land. here is a source provided for the supplying of mineral fire, a source which is inexhaustible or unlimited, unless we are to circumscribe it with regard to time, and the necessary ingredients; such as the matter of light, carbonic matter, and the hydrogenous principle. but it is not upon any deficiency of this kind that our author founds his estimate; it is upon the superfluity of combustible materials which is actually found in this earth, after it had been properly consolidated and raised above the surface of the sea. this is a method of reasoning calculated to convince only those who do not understand it; it is as if we should conclude that a person had died of want, because he had left provision behind him. our author certainly means to employ nothing but the combustible minerals of the present earth, in feeding the subterraneous fire which is to concoct a future earth; in that case, i will allow that his provision is deficient; but this is not my theory. i am not here to enter into any argument concerning subterraneous fire; the reader will find, in the foregoing theory, my reasons for concluding, that subterraneous fire had existed previous to, and ever since, the formation of this earth,--that it exists in all its vigour at this day,--that there is, in the constitution of this earth, a superfluity of subterranean heat,--and that there is wisely provided a proper remedy against any destructive effect to the system, that might arise from that superabundant provision of this necessary agent. had our author attended to the ocular proof that we have of the actual existence of subterraneous fire, and to the physical demonstrations which i have given of the effects of heat in melting mineral bodies, he must have seen that those arguments of his, with regard to the difficulty or impossibility of procuring that fire, can only show the error of his reasoning. i am far from supposing that my theory may be free from inconsistency or error; i am only maintaining that, in all his confident assertions, this author has not hitherto pointed any of these out. so far i have answered our author's objections as to consolidation, and i have given a specimen of his reasoning upon that subject; but with regard to my theory of the earth, although simple fluidity, without heat, would have answered the purpose of consolidating strata that had been formed at the bottom of the sea, it was necessary to provide a power for raising those consolidated strata from that low place to the summits of the continents; now, in supposing heat to be the cause of that fluidity which had been employed in the consolidation of those submarine masses, we find a power capable of erecting continents, and the only power, so far as i see, which natural philosophy can employ for that purpose. thus i was led, from the consolidation of strata, to understand the nature of the elevating power, and, from the nature of that power, again to understand the cause of fluidity by which the rocks and stones of this earth had been consolidated. having thus, without employing the evidence of any fire or _burning_, been necessarily led to conclude an extreme degree of heat exerted in the mineral regions, i next inquire how far there are any appearances from whence we might conclude whether that active subterraneous power still subsists, and what may be the nature of that power. when first i conceived my theory, naturalists were far from suspecting that basaltic rocks were of volcanic origin; i could not then have employed an argument from these rocks as i may do now, for proving that the fires, which we see almost daily issuing with such force from volcanos, are a continuation of that active cause which has so evidently been exerted in all times, and in all places, so far as have been examined of this earth. with regard to the degree of heat in that subterraneous fire, our author, after proving that combustible materials would not burn in the mineral regions, then says, that suppose they were to burn, this would be "incapable of forming a heat even equal to that of our common furnaces, as mr dolomieu has clearly shown to be the case with respect to volcanic heat." the place to which he alludes, i believe to be that which i have quoted from the journal de physique (part i. page ) to which i here beg leave to refer the reader. after what i have already said, this subject will appear to be of little concern to me; but, it must be considered, that my object, in these answers, is not so much to justify the theory which i have given, as it is to remove that prejudice which, to those who are not master of chemical and mineral subjects, will naturally arise from the opinion or authority of a scientific man, and a chemist; therefore, i think it my business to show how much he has misconceived the matter which he treats of, and how much he misunderstands the subject of my theory. mr dolomieu alleges that the volcanic fire operates in the melting of bodies, not by the intensity of its heat, which is the means employed by us in our operations, but in the long continuance of its action. but in that proposition, this philosopher is merely giving us his opinion; and, this opinion our author mistakes, i suppose, for the fact on which that opinion had been (perhaps reasonably) founded. the reader will see, in the place quoted, or in the _avant-propos_ to his _mémoire sur les iles ponces_, the fact to be this; that the chevalier dolomieu finds those bodies which we either cannot melt in our fires, or which we cannot melt without changing them by calcination and vitrification, he finds, i say, these substances had actually been melted with his lavas; he also finds those substances, which are necessarily dissipated in our fires, to have been retained in those melted mineral substances. had our author quoted the text, instead of giving us his own interpretation, he could not have offered a stronger confirmation of my theory; which certainly is not concerned with the particular intensity of volcanic fire, and far less with what may be the opinion of any naturalist with regard to that intensity, but only with the efficacy of that volcanic heat for the melting of mineral substances. now this efficacy of volcanic fire, so far as we are to found upon the authority given on this occasion, is clearly confirmed by the observations of a most intelligent mineralist, and one who is actually a patron of the opposite theory to that which i have given. this being the state of the case, must i not conclude, that our author has misunderstood the subject, and that he has been led to give a mutilated opinion of mr dolomieu, in order to refute my theory, when either the entire opinion, or the facts on which the opinion had been founded, would have confirmed it? i have thus endeavoured to put in its true light a species of reasoning, which, while it assumes the air and form of that inductive train of thought employed by men of science for the investigation of nature, is only fit to mislead the unwary, and, when closely examined, will appear to be inconsequential or unfounded. how mortifying then to find, that one may be employed almost a lifetime in generalising the phenomena of nature, or in gathering an infinity of evidence for the forming of a theory, and that the consequence of this shall only be to give offence, and to receive reproach from those who see not things in the same light!--while man has to learn, mankind must have different opinions. it is the prerogative of man to form opinions; these indeed are often, commonly i may say, erroneous; but they are commonly corrected, and it is thus that truth in general is made to appear. i wrote a general theory for the inspection of philosophers, who doubtless will point out its errors; but this requires the study of nature, which is not the work of a day; and, in this political age, the study of nature seems to be but little pursued by our philosophers. in the mean time, there are, on the one hand, sceptical philosophers, who think there is nothing certain in nature, because there is misconception in the mind of man; on the other hand, there are many credulous amateurs, who go to nature to be entertained as we go to see a pantomime: but there are also superficial reasoning men, who think themselves qualified to write on subjects on which they may have read in books,--subjects which they may have seen in cabinets, and which, perhaps, they have just learned to name; without truly knowing what they see, they think they know those regions of the earth which never can be seen; and they judge of the great operations of the mineral kingdom, from having kindled a fire, and looked into the bottom of a little crucible. in the theory of the earth which was published, i was anxious to warn the reader against the notion that subterraneous heat and fusion could be compared with that which we induce by our chemical operations on mineral substances here upon the surface of the earth; yet, notwithstanding all the precaution i had taken, our author has bestowed four quarto pages in proving to me, that our fires have an effect upon mineral substances different from that of the subterraneous power which i would employ. he then sets about combining metals with sulphur in the moist way, as if that were any more to his purpose than is the making of a stalactite for the explanation of marble. silver and lead may be sulphurated, as he says, with hepatic gas; but, has the sulphurated solid ores of those metals, and that of iron, been formed in the moist way, as in some measure they may be by the fusion of our fires? but, even suppose that this were the case, could that explain a thousand other appearances which are inconsistent with the operation of water? we see aerated lead dissolved in the excavations of our mines, and again concreted by the separation of the evaporated solvent, in like manner as stalactical concretions are made of calcareous earth; but, so far from explaining mineral appearances, as having had their concretions formed in the same manner, here is the most convincing argument against it; for, among the infinite variety of mineral productions which we find in nature, why does no other example of aqueous concretion ever occur upon the surface of the earth except those which we understand so well, and which we therefore know cannot be performed in the bodies of strata not exposed to the evaporation of the solvent, a circumstance which is necessary. i have given a very remarkable example of mineral fusion, in reguline manganese, (as the reader will see in page .) it is not that this example is more to the purpose of my theory than what may be found in every species of stone; but this example speaks so immediately to the common sense of mankind, (who are often convinced by a general resemblance of things, when they may not see the force of demonstration from an abstract principle) that i thought it deserved a place on that account, as well as being a curious example, but more particularly to my antagonist, who has been pleased (very improperly indeed) to try some part of my theory in the fire, here is an example which should have been absolutely in point, and without any manner of exception:--has he acknowledged this?--no; he has, on the contrary, endeavoured to set this very example aside. on this occasion, he says, "manganese has been found in a reguline state by m. de la peyrouse, and in small grains, as when produced by fire. true; but it was mixed with a large quantity of iron, which is often, found in that form without any suspicion of fusion. a fire capable of melting quartz might surely produce it in larger masses." we have here a kind of two arguments, for removing the effect of this example; and i shall consider them separately. the first of these is, the not being suspected of having been in fusion; now, if this were to be admitted as an argument against the igneous origin of stony substances, it might have superseded the adducing of any other, for it is applicable perhaps to every mineral; but we must here examine the case more minutely. this argument, of the manganese being in a mine of iron, if i understand it rightly, amounts to this, that, as iron ore is not suspected of having been melted, therefore, we should doubt the manganese having been so. if this be our author's meaning, it is not the fair conclusion which the case admits of; for, so far as the manganese appears evidently to have been in a melted state, the iron ore should be _suspected_ of having been also in fusion, were there no other evidence of that fact. in science, however, it is not suspicion that should be employed in physical investigation; the question at present is; if the phenomena of the case correspond to the conclusion which the intelligent mineralist, who examined them, has formed? and, to this question, our author gives no direct answer. he says, _iron is often found in that form without any suspicion of fusion_. this is what i am now to answer. the form in which the manganese appears is one of the strongest proofs of those masses having been in fusion; and, if iron should ever be found in that form, it must give the same proof of mineral fusion as this example of manganese; let us then see the nature of this evidence. the form of the manganese is that of a fluid body collecting itself into a spherical figure by the cohesion or attraction of its particles, so far as may be admitted by other circumstances; but, being here refilled by the solid part on which it rests, this spherical body is flattened by the gravitation of its substance. now here is a regular form, which demonstrates the masses to have been in the state of fusion; for, there is no other way in which that form of those reguline masses could have been induced. there now remains to be considered what our author has observed respecting the intensity of the fire and size of the masses. "a fire capable of melting quartz might surely produce it (meaning the manganese) in larger masses." m. de la peyrouse says, that those masses were in all respects as if formed by art, only much larger, as the powers of nature exceed those of our laboratories. what then is it that is here meant to be disputed? we are comparing the operation of nature and that of art, and these are to be judged of by the product which we examine; but the quantity, in this case, or the size of the masses, makes no part of the evidence, and therefore is here most improperly mentioned by our author. with regard again to the nature of the fire by which the fusion had been produced, he is much mistaken if he imagines that the reduction of the reguline or metallic manganese depends upon the intensity of the heat; it depends upon circumstances proper for the separation of the oxygenating principle from the calx, in like manner as the calcination of calcareous spar must depend upon circumstances proper for allowing the separation of the carbonic acid or fixed air. but do not let us lose sight of our proper subject, by examining things foreign or not so immediately to the purpose. we are only inquiring if those flattened spheres of native manganese had been formed by water, or if it were by fusion; for, our author agrees that there is no other way. why then does he endeavour to evade giving a direct answer, and fly away to consider the quantity of the product, as if that had any thing to do with, the question, or as if that quantity were not sufficient, neither of which is the case. in short, our author's whole observation, on this occasion, looks as if he were willing to destroy, by insinuation, the force of an argument which proves the theory of mineral fusion; and that he wishes to render doubtful, by a species of sophistry, what in fair reasoning he cannot deny. our author has written upon the subject of phlogiston; one would suppose that he should be well acquainted with inflammable bodies at least; let us see then what he has to observe upon that subject. he quotes from my theory, that spar, quartz, pyrites, crystallised upon or near each other, and adhering to coal, or mixed with bitumen, etc. are found; circumstances that cannot be explained in the hypothesis of solution in the moist way.--he then answers;--"not exactly, nor with certainty; which is not wonderful: but they are still less explicable in the hypothesis of dry solution, as must be apparent from what has been already said. how coal, an infusible substance, could be spread into strata by mere heat, is to me incomprehensible."--it is only upon the last sentence that i am here to remark: this, i believe, will be a sufficient specimen of our author's understanding, with regard at least to my theory which he is here examining. the reader will see what i have said upon the subject of coal, by turning back to the second section of the preceding chapter. i had given almost three quarto pages upon that subject, endeavouring to explain how all the different degrees of _infusibility_ were produced, by means of heat and distillation, in strata which had been originally more or less oily, bituminous, and _fusible_; and now our author says, that it is incomprehensible to him, how coal, _an infusible substance_, could be spread into strata by mere heat.--so it truly may, either to him or to any other person; but, it appears to me almost as incomprehensible, how a person of common understanding should read my dissertation, and impute to it a thing so contrary to its doctrine. nothing can better illustrate the misconceived view that our author seems to have taken of the two opposite theories, (_i. e_. of consolidation by means of heat, and by means of water alone,) than his observation upon the case of mineral alkali. to that irrefragable argument (which dr black suggested) in proof of this substance having been in a state of fusion in the mineral regions, our author makes the following reply; "what then will our author say of the vast masses of this salt which are found with their full quantity of water of crystallization?"--there is in this proposition, insignificant as it may seem, a confusion of ideas, which it certainly cannot be thought worth while to investigate; but, so far as the doctrine of the aqueous theory may be considered as here concerned, it will be proper that i should give some answer to the question so triumphantly put to me. our author is in a mistake in supposing that dr black had written any thing upon the subject; he had only suggested the argument of this example of mineral alkali to me, as i have mentioned; and, the use i made of that argument was to corroborate the example i had given of sal gem. if, therefore, our author does not deny the inference from the state of that mineral alkali, his observation upon it must refer to something which this other example of his is to prove on the opposite side, or to support the aqueous instead of the igneous theory; and, this is a subject which i am always willing to examine in the most impartial manner, having a desire to know the true effect of aqueous solution in the consolidation of mineral bodies, and having no objection to allow it any thing which it can possibly produce, although denying that it can do every thing, as many mineralists seem to think. the question, with regard to this example of our author's of a mineral alkali with its water of crystallization, must be this, whether those saline bodies had been concreted by the evaporation of the aqueous solvent with which they had been introduced, or by the congelation of that saline substance from a fluid state of fusion; for, surely, we are not to suppose those bodies to have been created in the place and state in which we find them. with regard to the evaporation or separation of the aqueous solvent, this may be easily conceived according to the igneous theory; but, the aqueous theory has not any means for the producing of that effect in the mineral regions, which is the only place we are here concerned with. therefore, this example of a concreted body of salt, whatever it may prove in other respects, can neither diminish the evidence of my theory with regard to the igneous origin of stony substances, nor can it contribute to support the opposite supposition of an aqueous origin to them. but to show how little reason our author had for exulting in that question which he so confidently proposed in order to defeat my argument, let us consider this matter a little farther. i will for a moment allow the aqueous theory to have the means for separating the water from the saline solution, and thus to concrete the saline substance in the bowels of the earth; this concretion then is to be examined with a view to investigate the last state of this body, which is to inform us with regard to those mineral operations. but, our author has not mentioned whether those masses appear to have been crystallised from the aqueous solution, or if they appear to have been congealed from the melted state of their _aqueous fusion_.--has he ever thought of this? now this is so material a point in the view with which that example has been held out to us, that, without showing that this salt had crystallised from the solution, he has no right to employ it as an example; and if, on the other hand, it should appear to have simply congealed from the state of aqueous fusion, then, instead of answering the purpose for which our author gave it, it would refute his supposition, as certainly as the example which i have given. so far i have reasoned upon the supposition of this alkali, with its water of crystallization, being truly a mineral concretion; but, i see no authority for such a supposition: it certainly may be otherwise; and, in that case, our author would have no more right to give it as an example in opposition to dr black's argument, than he would have to give the crystallization of sea-salt, on turk's island, in opposition to the example which i had given, of the salt rock, at northwych in cheshire, having been in the state of fusion. it certainly was incumbent on our author to have informed us, if those masses of salt were found in, what may be properly termed, their mineral state; or, if the state in which they are found at present had been produced by the influences of the atmosphere, transforming that saline substance from its mineral state, as happens upon so many other occasions; i am inclined to suspect that this last is truly the case. it may be thought illiberal in me to suppose a natural philosopher thus holding out an example that could only serve to lead us into error, or to mislead our judgment with regard to those two theories which is the subject of consideration. this certainly would be the case, almost on any other occasion; but, when i find every argument and example, employed in this dissertation, to be either unfounded or misjudged, whether am i to conclude our author, on this occasion, to be consistent with himself, or not? i have but one article more to observe upon. i had given, as i thought, a kind of demonstration, from the internal evidence of the stone, that granite had been in the fluid state of fusion, and had concreted by crystallization and congelation from that melted state. this no doubt must be a stumbling block to those who maintain that granite mountains are the primitive parts of our earth; and who, like our author, suppose that "things may have been originally, as at present, in a solid state." it must also be a great, if not an invincible obstacle in the way of the aqueous theory, which thus endeavours to explain those granite veins that are found traversing strata, and therefore necessarily of a posterior formation. to remove that obstacle in the way of the aqueous theory, or to carry that theory over the obstacle which he cannot remove, our author undertakes to refute my theory with regard to the igneous origin of stony substances, by giving an example of granite formed upon the surface of the earth by means of water, or in what is called the moist way; and he closes his dissertation with this example as an _experimentum crucis_. it is therefore necessary that i take this demonstration of our author into particular consideration; for, surely, independent of our controversy, which is perhaps of little moment, here is the most interesting experiment, as it is announced, that mineralogy could be enriched with. "to close this controversy," says our author, "i shall only add, that granite, recently formed in the moist way, has been frequently found."--of that remarkable event, however, he has selected only one example. this is to be found upon the oder; and the authority upon which our author has given it, is that of lasius hartz. the formation of a granite stone, from granite sand, by means of water, is inconsistent with our chemical knowledge of those mineral substances which constitute that stone; it is repugnant to the phenomena which appear from the inspection of the natural bodies of this kind; and it is directly contrary to the universal experience in granite countries, where, instead of any thing concreting, every thing is going into decay, from the loose stones and sand of granite, to the solid rock and mountains which are always in a state of degradation. therefore, to have any credit given to such a story, would require the most scientific evidence in its favour. now, in order that others may judge whether this has been the case in this example, i will transcribe what our author has said upon the subject; and then i will give the view in which it appears to me. he says, "a mole having been constructed in the oder in the year , feet long, feet in height, feet broad at bottom, and at the top, its sides only were granite, without any other cement than moss; the middle space was entirely filled with granite sand. in a short time this concreted into a substance so compact as to be impenetrable by water."--here is an example, according to our author, of _granite formed in the moist way_. but now, i must ask to see the evidence of that fact; for, from what our author has told us, i do not even see reason to conclude that there was the least concretion, or any stone formed at all. a body of sand will be _so compacted as to be impenetrable by water_, with the introduction of a very little mud, and without any degree of concretion; muddy water, indeed, cannot be made to pass through such a body without compacting it so; and this every body finds, to their cost, who have attempted to make a filter of that kind. but i shall suppose lasius has informed our author that there had been a petrifaction in this case; and, before i admit this example of the formation of granite, i must ask what sort of a granite it was;--whether of two, three, or four ingredients; and, how these were disposed. if, again, it were not properly a granite, but a stone formed of granite sand, what is the cementing substance?--is it quartz, felt-spar, mica, or schorl?--or, was it calcareous? if our author knows any thing about these necessary questions, why has he not informed us, as minutely as he has done with regard to the dimensions of the mole, with which we certainly are less concerned? if, again, he knows no more about the matter than what he has informed us of, he must have strangely imposed upon himself, to suppose that he was giving us an example of the _formation of granite in the moist way_, when he has only described an effectual way of retaining water, by means of sand and mud. chap. iii. of physical systems, and geological theories, in general. in the first chapter i have given a general theory of the earth, with such proofs as i thought were sufficient for the information of intelligent men, who might satisfy themselves by examining the facts on which the reasoning in that theory had been founded. in the second chapter, i have endeavoured to remove the objections which have been made to that theory, by a strenuous patron of the commonly received opinion of mineralogists and geologists,--an opinion which, if not diametrically opposite, differs essentially from mine. but now i am to examine nature more particularly, in order to compare those different opinions with the actual state of things, on which every physical theory must be founded. therefore, the opinions of other geologists should be clearly stated, that so a fair comparison may be made of theories which are to represent the system of this earth. now, if i am to compare that which i have given as a theory of the earth, with the theories given by others under that denomination, i find so little similarity, in the things to be compared, that no other judgment could hence be formed, perhaps, than that they had little or no resemblance. i see certain treatises named theories of the earth; but, i find not any thing that entitles them to be considered as such, unless it be their endeavouring to explain certain appearances which are observed in the earth. that a proper theory of the earth should explain all those appearances is true; but, it does not hold, conversely, that the explanation of an appearance should constitute a theory of the earth. so far as the theory of the earth shall be considered as the philosophy or physical knowledge of this world, that is to say, a general view of the means by which the end or purpose is attained, nothing can be properly esteemed such a theory unless it lead, in some degree, to the forming of that general view of things. but now, let us see what we have to examine in that respect. we have, first, burnet's theory of the earth. this surely cannot be considered in any other light than as a dream, formed upon the poetic fiction of a golden age, and that of iron which had succeeded it; at the same time, there are certain appearances in the earth which would, in a partial view of things, seem to justify that imagination. in telliamed, again, we have a very ingenious theory, with regard to the production of the earth above the surface of the sea, and of the origin of those land animals which now inhabit that earth. this is a theory which has something in it like a regular system, such as we might expect to find in nature; but, it is only a physical romance, and cannot be considered in a serious view, although apparently better founded than most of that which has been wrote upon the subject. we have then a theory of a very different kind; this is that of the count de buffon. here is a theory, not founded on any regular system, but upon an irregularity of nature, or an accident supposed to have happened to the sun. but, are we to consider as a theory of the earth, an accident by which a planetary body had been made to increase the number of these in the solar system? the circumvolution of a planetary body (allowing it to have happened in that manner) cannot form the system of a world, such as our earth exhibits; and, in forming a theory of the earth, it is required to see the aptitude of every part of this complicated machine to fulfil the purpose of its intention, and not to suppose the wise system of this world to have arisen from, the cooling of a lump of melted matter which had belonged to another body. when we consider the power and wisdom that must have been exerted in the contriving, creating, and maintaining this living world which sustains such a variety of plants and animals, the revolution of a mass of dead matter according to the laws of projectiles, although in perfect wisdom, is but like a unite among an infinite series of ascending numbers. after the theory of that eloquent writer, founded on a mere accident, or rather the error of a comet which produced the beautiful system of this world, m. de luc, in his theory of the earth, has given us the history of a disaster which befell this well contrived world;--a disaster which caused the general deluge, and which, without a miracle, must have undone a system of living beings that are so well adapted to the present state of things. but, surely, general deluges form no part of the theory of the earth; for, the purpose of this earth is evidently to maintain vegetable and animal life, and not to destroy them. besides these imaginary great operations in the natural history of this earth, we have also certain suppositions of geologists and mineralists with regard to the effect of water, for explaining to us the consolidation of the loose materials of which the strata of the earth had been composed, and also for producing every other appearance, or any which shall happen to occur in the examination of the earth, and require to be explained. that this is no exaggerated representation, and that this is all we have as a theory, in the suppositions of those geologists, will appear from the following state of the case. they suppose water the agent employed in forming the solid bodies of the earth, and in producing those crystallised bodies which appear in the mineral kingdom. that this is a mere supposition will appear by considering; first, that they do not know how this agent water is to operate in producing those effects; nor have they any direct proof of the fact which is alleged, from a very fallaceous analogy; and, secondly, that they cannot tell us where this operation is to be performed. they cannot say that it is in the earth above the level of the sea: for, the same appearances are found as deep as we can examine below that level; besides, we see that water has the opposite effect upon the surface of the earth, through which it percolates dissolving soluble substances, and thus resolving solid bodies in preparing soil for plants. if, again, it be below the level of the sea, that strata of the earth are supposed to be consolidated by the infiltration of that water which falls from the heavens; this cannot be allowed, so far as whatever of the earth is bibulous, in that place, must have been always full of water, consequently cannot admit of that supposed infiltration. but allowing those suppositions to be true, there is nothing in them like a theory of the earth,--a theory that should bring the operations of the world into the regularity of ends and means, and, by generalizing these regular events, show us the operation of perfect intelligence forming a design; they are only an attempt to show how certain things, which we see, have happened without any perceivable design, or without any farther design than this particular effect which we perceive. if we believe that there is almighty power, and supreme wisdom employed for sustaining that beautiful system of plants and animals which is so interesting to us, we must certainly conclude, that the earth, on which this system of living things depends, has been constructed on principles that are adequate to the end proposed, and procure it a perfection which it is our business to explore. therefore, a proper system of the earth should lead us to see that wise contraction, by which this earth is made to answer the purpose of its intention and to preserve itself from every accident by which the design of this living world might be frustrated as this world is an active scene, or a material machine moving in all its parts, we must see how this machine is so contrived, as either to have those parts to move without wearing and decay, or to have those parts, which are wasting and decaying, again repaired. a rock or stone is not a subject that, of itself, may interest a philosopher to study; but, when he comes to see the necessity of those hard bodies, in the constitution of this earth, or for the permanency of the land on which we dwell, and when he finds that there are means wisely provided for the renovation of this necessary decaying part, as well as that of every other, he then, with pleasure, contemplates this manifestation of design, and thus connects the mineral system of this earth with that by which the heavenly bodies are made to move perpetually in their orbits. it is not, therefore, simply by seeing the concretion of mineral bodies that a philosopher is to be gratified in his his intellectual pursuit, but by the contemplation of that system in which the necessary resolution of this earth, while at present it serves the purpose of vegetation, or the fertility of our soil, is the very means employed in furnishing the materials of future land. it is such a view as this that i have endeavoured to represent in the theory which i have given. i have there stated the present situation of things, by which we are led to perceive a former state; and, from that necessary progress of actual things, i have concluded a certain system according to which things will be changed, without any accident or error. it is by tracing this regular system in nature that a philosopher is to perceive the wisdom with which this world has been contrived; but, he must see that wisdom founded upon the aptitude of all the parts to fulfil the intention of the design; and that intention is to be deduced from the end which is known to be attained. thus we are first to reason from effect to cause, in seeing the order of that which has already happened; and then, from those known causes, to reason forwards, so as to conceive that which is to come to pass in time. such would be the philosophy of this earth, formed by the highest generalisation of phenomena, a generalisation which had required the particular investigation of inductive reasoning. that no such theory as this, founded upon water as an agent operating in the changes of this earth, has yet appeared, will, i believe be easily allowed. with regard again to fire as an agent in the mineral operations of this earth, geologists have formed no consistent theory. they see volcanoes in all the quarters of the globe, and from those burning mountains, they conjecture other mountains have been formed. but a burning mountain is only a matter of fact; and, they have not on this formed any general principle, for establishing what may be called a theory of the earth. those who have considered subterraneous fires as producing certain effects, neither know how these have been procured, nor do they see the proper purpose for which they are employed in the system of this world. in this case, the agent fire is only seen as a destructive element, in like manner as deluges of water have been attributed by others to changes which have happened in the natural state of things. these operations are seen only as the accidents of nature, and not as part of that design by which the earth, which is necessarily wasted in the operations of the world, is to be repaired. so far from employing heat or subterraneous fire as an agent in the mineral operations of the earth, the volcanic philosophers do not even attempt to explain upon that principle the frequent nodules of calcareous, zeolite, and other spatose and agaty substances, in those basaltic bodies which they consider as lavas. instead then of learning to see the operation of heat as a general principle of mineral consolidation and crystallization, the volcanic philosophers endeavour to explain those particular appearances, which they think inconsistent with fusion, by aqueous infiltration, no otherwise than other mineralists who do not admit the igneous origin of those basaltic bodies. thus, that great agent, subterraneous heat, has never been employed by geologists, as a general principle in the theory of the earth; it has been only considered as an occasional circumstance, or as the accident of having certain mineral bodies, which are inflammable, kindled in the earth, without so much as seeing how that may be done. this agent heat, then, is a new principle to be employed in forming a theory of the earth; a principle that must have been in the constitution of this globe, when contrived to subsist as a world, and to maintain a system of living bodies perpetuating their species. it is therefore necessary to connect this great mineral principle, subterraneous fire or heat, with the other operations of the world, in forming a general theory. for, whether we are to consider those great and constant explosions of mineral fire as a principal agent in the design, or only as a casual event depending upon circumstances which give occasion to an operation of such magnitude, here is an object that must surely have its place in every general theory of the earth. in examining things which actually exist, and which have proceeded in a certain order, it is natural to look for that which had been first; man desires to know what had been the beginning of those things which now appear. but when, in forming a theory of the earth, a geologist shall indulge his fancy in framing, without evidence, that which had preceded the present order of things, he then either misleads himself, or writes a fable for the amusement of his reader. a theory of the earth, which has for object truth, can have no retrospect to that which had preceded the present order of this world; for, this order alone is what we have to reason upon; and to reason without data is nothing but delusion. a theory, therefore, which is limited to the actual constitution of this earth, cannot be allowed to proceed one step beyond the present order of things. but, having surveyed the order of this living world, and having investigated the progress of this active scene of life, death and circulation, we find ample data on which to found a train of the most conclusive reasoning with regard to a general design. it is thus that there is to be perceived another system of active things for the contemplation of our mind;--things which, though not immediately within our view, are not the less certain in being out of our sight; and things which must necessarily be comprehended in the theory of the earth, if we are to give stability to it as a world sustaining plants and animals. this is a mineral system, by which the decayed constitution of an earth, or fruitful surface of habitable land, may be continually renewed in proportion as it is wasted in the operations of this world. it is in this mineral system that i have occasion to compare the explanations, which i give of certain natural appearances, with the theories or explanations which have been given by others, and which are generally received as the proper theory of those mineral operations. i am, therefore, to examine those different opinions, respecting the means employed by nature for producing particular appearances in the construction of our land, appearances which must be explained in some consistent mineral theory. these appearances may all be comprehended under two heads, which are now to be mentioned, in order to see the importance of their explanation, or purpose which such an explanation is to serve in a theory of the earth. the first kind of these appearances is that of known bodies which we find composing part of the masses of our land, bodies whose natural history we know, as having existed in another state previous to the composition of this earth where they now are found; these are the relicts or parts of animal and vegetable bodies, and various stony substances broken and worn by attrition, all which had belonged to a former earth. by means of these known objects, we are to learn a great deal of the natural history of this earth; and, it is in tracing that history, from where we first perceive it, to the present state of things, that forms the subject of a geological and mineralogical theory of this earth. but, we are more especially enabled to trace those operations of the earth, by means of the second kind of appearances, which are now to be mentioned. these again are the evident changes which those known bodies have undergone, and which have been induced upon such collected masses of which those bodies constitute a part. these changes are of three sorts; _first_, the solid state, and various degrees of it, in which we now find those masses which had been originally formed by the collection of loose and incoherent materials; _secondly_, the subsequent changes which have evidently happened to those consolidated masses which have been broken and displaced, and which have had other mineral substances introduced into those broken and disordered parts; and, _lastly_, that great change of situation which has happened to this compound mass formed originally at the bottom of the sea, a mass which, after being consolidated in the mineral region, is now situated in the atmosphere above the surface of the sea. in this manner we are led to the system of the world, or theory of the earth in general; for, that great change of situation, which our land has undergone, cannot be considered as the work of accident, or any other than an essential part in the system of this world. it is therefore a proper view of the necessary connection and mutual dependence of all those different systems of changing things that forms the theory of this earth as a world, or as that active part of nature which the philosophy of this earth has to explore. the animal system is the first or last of these; next comes the vegetable system, on which the life of animals depends; then comes the system of this earth, composed of atmosphere, sea, and land, and comprehending the various chemical, mechanical, and meteorologically operations which take place upon that surface where vegetation must proceed; and, lastly, we have the mineral system to contemplate, a system in which the wasting surface of the earth is employed in laying the foundation of future land within the sea, and a system in which the mineral operations are employed in concocting that future land. now, such must surely be the theory of this earth, if the land is continually wasting in the operations of this world; for, to acknowledge the perfection of those systems of plants and animals perpetuating their species, and to suppose the system of this earth on which they must depend, to be imperfect, and in time to perish, would be to reason inconsistently or absurdly. this is the view of nature that i would wish philosophers to take; but, there are certain prejudices of education or prepossession of opinion among them to be overcome, before they can be brought to see those fundamental propositions,--the wasting of the land, and the necessity of its renovation by the co-operation of the mineral system. let us then consider how men of science, in examining the mineral state of things, and reasoning from those appearances by which we are to learn the physiology of this earth, have misled themselves with regard to physical causes, and formed certain mineralogical and geological theories, by which their judgment is so perverted, in examining nature, as to exclude them from the proper means of correcting their first erroneous notions, or render them blind to the clearest evidence of any other theory that is proposed. when men of science reason upon subjects where the ideas are distinct and definite, with terms appropriated to the ideas, they come to conclusions in which there is no difference of opinion. it is otherwise in physical subjects, where things are to be assimilated, in being properly compared; there, things are not always compared in similar and equal circumstances or conditions; and there, philosophers often draw conclusions beyond the analogy of the things compared, and thus judge without data. when, for example, they would form the physical induction, with regard to the effect of fire or water upon certain substances in the mineral regions, from the analogy of such events as may be observed upon the surface of the earth, they are apt to judge of things acting under different circumstances or conditions, consequently not producing similar effects; in which case, they are judging without reason, that is, instead of inductive reasoning from actual data or physical truth, they are forming data to themselves purely by supposition, consequently, so far as these, imagined data may be wrong, the physical conclusion, of these philosophers may be erroneous. it is thus that philosophers have judged, with regard to the effects of fire and water upon mineral substances below the bottom of the sea, from what their chemistry had taught them to believe concerning bodies exposed to those agents in the atmosphere or on the surface of the earth. if in those two cases the circumstances were the same, or similar, consequently the conditions of the action not changed, then, the inductive reasoning, which they employ in that comparison, would be just; but, so far as it is evidently otherwise, to have employed that inductive conclusion for the explanation of mineral appearances, without having reason to believe that those changed circumstances of the case should not make any difference in the action or effect, is plainly to have transgressed the rules of scientific reasoning; consequently, instead of being a proper physical conclusion, it is only that imperfect reasoning of the vulgar which, by comparing things not properly analysed or distinguished, is so subject to be erroneous. this vague reasoning, therefore, cannot be admitted as a part of any geological or mineral theory. now i here maintain, that philosophers have judged in no other manner than by this false analogy, when they conclude that water is the agent by which mineral concretions have been formed. but it will be proper to state more particularly the case of that misunderstanding among mineral philosophers. in forming a geological theory, the general construction of this earth, and the materials of which it is composed, are such visible objects, and so evident to those who will take the pains to examine nature, that here is a subject in which there cannot be any doubt or difference of opinion. neither can there be any dispute concerning the place and situation of mass when it was first formed or composed; for, this is clearly proved, from every concomitant circumstance, to have been at the bottom of the sea. the only question in this case, that can be made, is, how that mass comes now to be a solid body, and above the surface of the sea in which it had been formed? with regard to the last, the opinions of philosophers have been so dissonant, so vague, and so unreasonable, as to draw to no conclusion. some suppose the land to be discovered by the gradual retreat of the ocean, without proposing to explain to us from whence had come the known materials of a former earth, which compose the highest summits of the mountains in the highest continents of the earth. others suppose the whole of a former earth to have subsided below the bottom even of the present sea, and together with it all the water of the former sea, from above the summits of the present mountains, which had then been at the bottom of the former sea. the placing of the bottom of the sea, or any part of it, in the atmosphere so as to be dry land, is no doubt a great operation to be performed, and a difficult task to be explained; but this is only an argument the more for philosophers to agree in adopting the most reasonable means. but though philosophers differ so widely in that point, this is not the case with regard to the concretion of mineral bodies; here mineralists seem to be almost all of one mind, at the same time without any reason, at least, without any other reason than that false analogy which they have inconsiderately formed from the operations of the surface of this earth. this great misunderstanding of mineralists has such an extensive and baneful effect in the judging of geological theories, that it will be proper here to explain how that has happened, and to shew the necessity of correcting that erroneous principle before any just opinion can be formed upon the subject. fire and water are two great agents in the system of this earth; it is therefore most natural to look for the operation of those agents in the changes which are made on bodies in the mineral regions; and as the consolidated state of those bodies, which had been collected at the bottom of the sea, may have been supposed to be induced either by fusion, or by the concretion from a solution, we are to consider how far natural appearance lead to the conclusion of the one or other of those two different operations. here, no doubt, we are to reason analogically from the known power and effects of those great agents; but, we must take care not to reason from a false analogy, by misunderstanding the circumstances of the case, or not attending to the necessary conditions in which those agents act.--we must not conclude that fire cannot burn in the mineral regions because our fires require the ventilation of the atmosphere; for, besides the actual exigence of mineral fire being a notorious matter of fact, we know that much more powerful means _may_ be employed by nature, for that mineral purpose of exciting heat, than those which we practise.--we must not conclude that mineral marble is formed in the same manner as we see a similar stony substance produced upon the surface of the earth, unless we should have reason to suppose the analogy to be complete. but, this is the very error into which mineral philosophers have fallen; and this is the subject which i am now to endeavour to illustrate. the manner in which those philosophers have deceived themselves when reasoning upon the subject of mineral concretion, is this: they see, that by means of water a stony substance is produced; and, this stony body so much resembles mineral marble as to be hardly distinguishable in certain cases. these mineral philosophers then, reasoning in the manner of the vulgar, or without analysing the subject to its principle, naturally attribute the formation of the mineral marble to a cause of the same sort; and, the mineral marble being found so intimately connected with all other mineral bodies, we must necessarily conclude, in reasoning according to the soundest principles, that all those different substances had been concreted in the same manner. thus, having once departed one step from the path of just investigation, our physical science is necessarily bewildered in the labyrinth of error. let us then, in re-examining our data, point out where lies that first devious step which had been impregnated with fixed air, or carbonic acid gas, (as it is called), dissolves a certain portion of mild calcareous earth or marble; consequently such acidulated water, that is, water impregnated with this gas, will, by filtrating through calcareous substances, become saturated with that solution of marble; and, this solution is what is called a _petrifying water_. when this solution is exposed to the action of the atmosphere, the acid gas, by means of which the stony substance is dissolved, evaporates from the solution, in having a stronger attraction for the atmospheric air; it is then that the marble, or calcareous substance, concretes and crystallises, separating from the water in a sparry state, and forming a very solid stone by the successive accretion from the solution, as it comes to be exposed to the influence of the atmosphere in flowing over the accumulating body. here is the source of their delusion; for, they do not distinguish properly the case of this solution of a stony substance concreting by means of the separation of its solvent, and the case of such a solution being in a place where that necessary condition cannot be supposed to exist; such as, e.g., the interstices among the particles of sand, clay, etc. deposited at the bottom of the sea, and accumulated in immense stratified masses. no example can better illustrate how pernicious it is to science to have admitted a false principle, on which a chain of reasoning is to proceed in forming a theory. mineral philosophers have founded their theory upon that deceitful analogy, which they had concluded between the stalactical concretions of petrifying waters and the marble formed in the mineral regions; thus, blinded by prejudice, they shut the door against the clearest evidence; and it is most difficult to make them see the error of their principle. but this is not to be wondered at, when we consider how few among philosophising men remount to the first principles of their theory; and, unless they shall thus remount to that first step, in which the concreting operation of a dissolved stony substance is supposed to take place without the necessary conditions for the petrifying operation, it is impossible to be convinced that their theory, thus formed with regard to mineral concretion, is merely supposition, and has no foundation in matter of fact from whence it should proceed. but this is not all; for, even supposing their theory to be well founded and just, it is plainly contradicted by natural appearances. according to that theory of aqueous consolidation, all the stratified bodies, of which this earth in general consists, should be found in the natural order of their regular formation; but, instead of this, they are found every where disturbed in that order more or less; in many places this order and regularity is so disturbed as hardly to be acknowledged; in most places we find those stratified bodies broken, dislocated, and contorted, and this aqueous theory of mineralists has neither the means for attaining that end, were it required in their theory, nor have they any such purpose in their theory, were that end attainable by the means which they employ. thus blinded by the prejudice of a false analogy, they do not even endeavour to gratify the human understanding (which naturally goes in quest of wisdom and design) by forming a hypothetical or specious theory of the mineral system; and they only amuse themselves with the supposition of an unknown operation of water for the explanation of their cabinet specimens, a supposition altogether ineffectual for the purpose of forming a habitable earth, and a supposition which is certainly contradicted by every natural appearance. thus, in examining geological and mineralogical theories, i am laid under the disagreeable necessity of pointing out the errors of physical principles which are assumed, the prejudices of theoretical opinions which have been received, and the misconceived notions which philosophers entertain with regard to the system of nature, in which may be perceived no ineffectual operation, nor any destructive intention, but the wise and benevolent purpose of preserving the present order of this world. but, though thus misled with regard to the cause of things, naturalists are every where making interesting observations in the mineral kingdom, i shall therefore avail myself of that instructive information, for the confirmation of my theory. it may now be proper to consider what must be required, in order to have a geological and mineral theory established upon scientific principles, or on such grounds as must give conviction to those who will examine the subject; for, unless we may clearly see that there are means for attaining that desirable end, few philosophers will be persuaded to pursue this branch of knowledge. a theory is nothing but the generalization of particular facts; and, in a theory of the earth, those facts must be taken from the observations of natural history. nature is considered as absolutely true; no error or contradiction can be found in nature. for, if such contradiction were truly found, if the stone, for example, which fell to day were to rise again to-morrow, there would be an end of natural philosophy, our principles would fail, and we would no longer investigate the rules of nature from our observations. every natural appearance, therefore, which is explained, _i.e._ which is made to come into the order of things that happen, must so far confirm the theory to which it then belongs. but is it necessary, that every particular appearance, among minerals, should be thus explained in a general theory of the earth? and, is any appearance, which is not explained by it, to be considered as sufficient to discredit or confute a theory which corresponded with every other appearance? here is a question which it would require some accuracy to resolve. if we knew all the powers of nature, and all the different conditions in which those powers may have their action varied, that is to say, if we were acquainted with every physical cause, then every natural effect, or all appearances upon the surface of this earth, might be explained in a theory that were just. but, seeing that this is far from being the case, and that there may be many causes of which we are as yet ignorant, as well as certain conditions in which the known action of powers may be varied, it must be evident, that a theory of the earth is not to be confuted by this argument alone, that there are, among natural bodies, certain appearances which are not explained by the theory. we must admit, that, not having all the data which natural philosophy requires, we cannot pretend to explain every thing which appears; and that our theories, which necessarily are imperfect, are not to be considered as erroneous when not explaining every thing which is in nature, but only when they are found contrary to or inconsistent with the laws of nature, which are known, and with which the case in question may be properly compared. but we may have different theories to compare with nature; and, in that case, the question is not, how far any of those theories should explain all natural appearances? but, how far any one particular theory might explain a phenomenon better than another? in this case of comparison, it will be evident, that if one theory explains natural appearances, then the opposite to that theory cannot be supposed to explain the same appearances. if for example, granite, porphyry, or basaltes, should be found naturally formed by fusion, the formation of those stones could not be supposed in any case as formed by water, although it could not be demonstrated that water is incapable of forming those mineral productions. in like manner, if those three bodies were proved to have been actually formed by water alone, then, in other cases where we should have no proof, they could not be supposed as having been formed by fire or fusion. it must be evident, that an equal degree of proof of those two different propositions would leave our judgment in suspence, unless that proof were perfect, in which case, we would have two different causes producing similar effects. but, if we shall have a sufficient proof upon the one side, and only a presumptive proof or probability upon the other, we must reject that probability or presumption, when opposed by a proof, although that proof were only an induction by reasoning from similar effects as following similar causes. _a fortiori_, if there be on one side a fair induction, without the least suspicion of error, and on the other nothing but a mere presumption founded upon a distant analogy, which could not even properly apply, then, the inductive proof would be as satisfactory as if there had not been any supposition on the opposite side. so far as a theory is formed in the generalization of natural appearances, that theory must be just, although it may not be perfect, as having comprehended every appearance; that is to say, a theory is not perfect until it be founded upon every natural appearance; in which case, those appearances will be explained by the theory. the theory of gravitation, though no ways doubtful, was not so perfect before the shape of this globe had been determined by actual measurement, and before the direction of the plummet had been tried upon shihallion, as after those observations had been made. but a theory which should be merely hypothetical, or founded upon a few appearances, can only be received as a theory, after it has been found to correspond properly with nature; it would then be held a proper explanation of those natural appearances with which it corresponded; and, the more of those phenomena that were thus explained by the theory, the more would that, which had been first conjectural, be converted into a theory legitimately founded upon natural appearances. matter of fact is that upon which science proceeds, by generalization, to form theory, for the purpose of philosophy, or the knowledge of all natural causes; and it is by the companion of these matters of fact with any theory, that such a theory will be tried. but, in judging of matter of fact, let us be cautious of deceiving ourselves, by substituting speculative reasoning in place of actual events. nature, as the subject of our observation, consists of two sorts of objects; for, things are either active, when we perceive change to take place in consequence of such action, or they are quiescent, when we perceive no change to take place. now, it is evident, that in judging of the active powers of nature from the quiescent objects of our information, we are liable to error, in misinterpreting the objects which we see; we thus form to ourselves false or erroneous opinion concerning the general laws of action, and the powers of nature. in comparing, therefore, generalised facts, or theory, with particular observations, there is required the greatest care, neither, on the one hand, to strain the appearances, so as to bring in to the theory a fact belonging to another class of things; nor, on the other, to condemn a proper theory, merely because that theory has not been extended to the explanation of every natural appearance. but, besides the misinterpretation of matters of fact, we are also to guard against the misrepresentation of natural appearances. whether warped by the prejudice of partial and erroneous theory, or deceived by the inaccuracy of superficial observation, naturalists are apt to see things in an improper light, and thus to reason from principles which cannot be admitted, and, which often lead to false conclusions. a naturalist, for example, comes to examine a cavity in the mines, he there finds water dropping down all around him, and he sees the cavity all hung with siliceous crystals; he then concludes, without hesitation, that here is to be perceived cause and effect, or that he actually sees the formation of those crystallizations from the operation of water. it is thus that i have been told by men of great mineral knowledge, men who must have had the best education upon that subject of mineralogy, and who have the superintendance of great mineral concerns in germany, that they had actually seen nature at work in that operation of forming rock-crystal;--they saw what i have now described; they could see no more; but, they saw what had convinced them of that which, there is every reason to believe, never happened. with regard to my theory, i wish for the most rigorous examination; and do not ask for any indulgence whatever, whether with regard to the principles on which the theory is built, or for the application of the theory to the explanation of natural appearances. but, let not geologists judge my theory by their imperfect notions of nature, or by those narrow views which they take of the present state of things;--let not mineralogists condemn my theory, for no other reason but because it does not correspond with their false principles, and those gratuitous suppositions by which they had been pleased to explain to themselves every thing before. first let them look into their own theory, and correct that erroneous principle, with regard to the action of water, or the assumption of unknown causes, upon which they have reasoned in forming their vague notions of the mineral region, before they can be properly qualified to examine, impartially, a theory which employs another principle. every thing which has come under my observation shall be, as far as i can, faithfully related; nor shall i withhold those which neither the present theory, nor any other that i am acquainted with, can, i think, explain. appearances cannot well be described except in relation to some theory or general arrangement of the subject; because the particular detail, of every part in a complicated appearance, would be endless and insignificant. when, however, any question in a theory depends upon the nature of an appearance, we cannot be too particular in describing that by which the question is to be decided. but though it be sometimes proper to be minute in a particular, it is always, and above all things, necessary to be distinct; and not to confound together things which are of different natures. for, though it be by finding similarity, in things which at first sight may seem different, that science is promoted and philosophy attained, yet, we must have a distinct view of those things which are to be assimilated; and surely the lowest state of knowledge in any subject, is the not distinguishing things which, though not to common observation different, are not truly the same. to confound, for example one stone with another, because they were both hard, friable, and heavy, would be to describe, with the superficial views of vulgar observation; whereas science specifies the weight and hardness, and thus accurately distinguishes the stone. before naturalists had learned to distinguish what they saw, and to describe, in known terms, those natural appearances, a theorist must have generalised only from his proper observation. this has been my case. when i first conceived my theory, few naturalists could write intelligibly upon the subject; but that is long ago, and things are much altered since; now there are most enlightened men making observations, and communicating natural knowledge. i have the satisfaction, almost every day, to compare the theory, which i had formed from my proper observations, with the actual state of things in almost every quarter of the globe. whether, therefore, we mean to try a theory by its application to such phenomena as are well understood, or to learn something from the application of particular phenomena to a well established theory, we shall always find it interesting to have appearances described; particularly such as may be referred to some general rule, as circumscribing it to certain conditions, or as finding rule in rule, that is to say, discovering those particular conditions in which the general laws of action may be affected. instead, for example, of the rule which we find in the application of heat for the fusion and evaporation of mineral substances upon the surface of this earth, we may find it necessary to consider the effect which changed circumstances produce in the mineral regions, and occasion a change of that rule of action which we have learned from experience, when melting and evaporating those substances in the atmosphere or on the surface of the earth. it is in this manner that a theory, which was formed by the generalization of particular facts, comes to be a source of information, by explaining to us certain appearances which otherwise we could not understand. thus, it was not the appearance of the tides that taught the theory of gravitation; it was the theory of gravitation that made us understand the appearance of the tides. in like manner, the law of gravitation, which was demonstrated from the motion of the moon in her orbit round this earth, when applied to the paths of comets, explained that appearance. our theory, of a central fire, has been formed upon the consolidation of the strata of this earth; but this theory is to be applied for the explanation of various different appearances. in this manner, two different purposes will be served; the trying of the theory by its application to phenomena; and the explanation of phenomena by the principles laid open in the theory. i may repeat it; a theory of the earth must ultimately depend upon matter of fact or particular observation; but those observations must be distinct, and those distinguished things must be generalised. we have just now given for an example, a distinction among stones, in knowing them by their sensible qualities. but, besides distinguishing those objects, we are also to inquire into the origin and cause of those things which are distinguished. here, again, we take into our aid the chemical as well as the mechanical properties of these several things; and hence learn to know on what their natural form and constitution may depend. having thus attained the natural philosophy of stones, we next inquire into the place and application of those things in nature; and in this manner we acquire some knowledge with regard to the natural constitution of this earth. we find this earth composed of known things; it is therefore the operations, required in these compositions, which form the natural philosophy of this earth, considered as a body of solid land. but, the solid land is only one part of the globe; therefore, the philosophy of the globe proceeds still farther by knowing the constitution of this planetary body, as consisting of different parts united for a purpose, which is that of a world. the general theory of this earth as a world, will thus appear to be a complex thing, which however founded upon simple principles, contains many subjects of discussion, and requires attention to a variety of particulars. for, not only the great features of this earth are to be explained by the theory, but also the most minute appearance, such as are to be found, even with microscopic observation, in every particular part. thus the nature, constitution, and cause of every particular appearance in the construction of this earth, are to be investigated in a geological theory, as well as that general constitution of the world in which all the particular parts are to be employed for a purpose. if the subject here examined shall be found properly explained, there will remain little doubt with regard to the justness of the theory, which will then be applicable to other appearances that may occur; although every appearance is not to be explained, in a manner equally satisfactory, by any theory which is not perfect. the first subject to be examined is the modern theory of primitive mountains. i have written several chapters upon that subject, having successively acquired more light in this interesting part of the theory, by observations of my own in several places of this country, as well as from the natural history of other countries. i shall give these nearly in the order in which they occurred, or had been written. chap. iv. the supposition of primitive mountains refuted. in the theory now given, the earth has been represented as a composition of different materials, which had existed in another form, and as the effect of natural operations; therefore, however various may be found the structure of our earth, and however dissimilar some parts of its composition may be in comparison with others, no part should be considered as original, in relation to the globe, or as primitive, in relation to second causes, _i.e._ physical operations by which those parts should have been formed. but it is pretended by naturalists, that there are certain primitive mountains in the earth, bodies which have had another origin than that of the general strata of the globe and subsequent masses; an origin, therefore, which cannot be considered as having been produced from natural operations, or as effected in the course of known causes. now, if it can be made to appear, that there is no solid ground for this distinction; and if it can be shown, that there is truly no mineral body in this earth which may not have been produced by operations natural to the globe, we should thus procure a certain confirmation of the doctrine. this also will be the more interesting, in being deduced from a part of natural appearances, which seemed to be inconsistent with the theory. certain masses or mountains of granite, are the only bodies of this earth which have apparently a certain pretension to this species of originality. these, therefore, must be now the subject of our examination. granite, considered by itself, does not appear to have any claim to originality in its nature. it is composed of bodies which are capable of being analyzed; and these are then found to be compositions of different substances, which are also sometimes variously proportioned. the feldspar and the mica, for example, as well as the schorl, are found variously coloured in different granites, and coloured in various proportions. besides the variety in the composition, or chemical mixture of the different bodies which compose granite, this rock admits of a great diversity, from the variety of its mechanical mixture, or from the different species of bodies which are its constituent parts. m. de saussure, who has examined this subject perhaps more than any other person, and who has had the very best opportunities for this purpose, says, that this composition may be found in all the different combinations which may be produced by every possible composition of or different kinds of stone, (page , voyage dans les alpes, etc.). neither does this fill up the measure of its variety; for, another source of change is found in the grain of this rock stone; i have a specimen of this variety from the size almost of sand to that of some inches. were granite, therefore, to be supposed as in the original state of its creation, nature would be considered as having operated in an indefinite diversity of ways, without that order and wisdom which we find in all her works; for here would be change without a principle, and variety without a purpose. there is no reason, however, to suppose granite original, more than any other composite rock, although we may be ignorant of the particular process in which it is formed, and although, comparatively in relation to certain other rocks, granite, or certain masses of this composition, may be found of a more ancient date. if granite be truly stratified, and those strata connected with the other strata of the earth, it can have no claim to originality; and the idea of primitive mountains, of late so much employed by natural philosophers, must vanish, in a more extensive view of the operations of the globe; but it is certain that granite, or a species of the same kind of stone, is thus found stratified. it is the _granit feuilletée_ of m. de saussure, and, if i mistake not, what is called _gneis_ by the germans. we have it also in our north alpine country of scotland; of this i have specimens, but have not seen it in its place. granite being thus found stratified, the masses of this stone cannot be allowed to have any right of priority over the schistus, its companion in the alpine countries, although m. de saussure, whose authority i would revere, has given it for the following reason; that it is found the most centrical in the chains of high mountains, or in alpine countries. now, supposing this fact to be general, as he has found it in the alps, no argument for the priority of those masses can be founded either upon the height or the situation of those granite mountains; for the height of the mountain depends upon the solidity and strength of the stone. now though it is not to be here maintained that granite is the most durable of those alpine rocks, yet as a mountain, either granite in general, or in particular, certain species of it, may be esteemed such, consequently, this massy stone, remaining highest in the mountainous region, will naturally be considered as the centre, and according to this rule, as having the pre-eminence in point of seniority. the rock which stands in competition with granite for the title of primitive in the order of mountains, is that micaceous stratified stone which is formed chiefly of quartz, but which admits of great variety like the granite. the difference between those two bodies does not consist in the materials of which they are composed, for, in their varieties, they may be in this respect the same, but in a certain regularity of composition, in this alpine stone, which evidently arises from stratification or subsidence in water. if we shall thus consider all the varieties of this alpine stone as being of one kind, and call it granite, then we shall distinguish in this body two different species, from whence perhaps some interesting conclusion may be formed with regard to the operations of the globe. these two species are, _first_, granite regular in its composition, or stratified in its construction; and, _secondly_, granite in mass, or irregular in its construction. let us now endeavour to make use of these generalizations and distinctions. in examining the great diversity of our whinstone, trap, or basaltes, it is found at last to granulate into granite; at the same time those two different species of rock-stone may be distinguished. a perfect granite has not in its composition necessarily any argillaceous earth, farther than may be in the natural constitution of its distinct parts; whereas, a perfect basalt may have abundance of this substance, without any quartz or any siliceous body. a perfect granite, is, therefore, an extremely hard stone, having quartz and feldspar for its basis; but a perfect whin or basaltes may be extremely soft, so as to cut easily with a knife. in like manner granite is a composition which graduates into porphyry; but porphyry is only whinstone of a harder species. therefore, though perfectly distinct, those three things graduate into each other, and may be considered as the same. granite and whinstone, or basaltes, though distinct compositions, thus graduating into each other; and whinstone, as well as porphyry, being without doubt a species of lava, we may consider the granite which is found in mass without stratification, in like manner as we do the masses of whinstone, basaltes, or swedish trap, as having flowed in the bowels of the earth, and thus been produced by the chance of place, without any proper form of its own, or in an irregular shape and construction. in this manner would be explained the irregular shape or structure of those granite masses; and thus great light would be thrown upon the waved structure of the stratified alpine stone, which, though it has not been made to flow, has been brought to a great degree of softness, so as to have the original straight lines of its stratification changed to those undulated or waving lines which are in some cases extremely much incurvated. it remains only to confirm this reasoning, upon our principles, by bringing actual observation to its support; and this we shall do from two of the best authorities. the chevalier de dolomieu, in describing the volcanic productions of etna, mentions a lava which had flowed from that mountain, and which may be considered as a granite. but m. de saussure has put this matter out of doubt by describing most accurately what he had seen both in the alps and at the city of lyons. these are veins of granite which have flowed from the contiguous mass into the stratified stone, and leave no doubt with regard to this proposition, that the granite had flowed in form of subterranean lava, although m. de saussure has drawn a very different conclusion from this appearance. i have also a specimen from this country of a vein of granite in a granite stone, the vein being of a smaller grain than that of the rock which it traverses.[ ] [note : this is what i had wrote upon, the subject of granite, before i had acquired such ample testimony from my own observations upon that species of rock. i have given some notice, in the d vol. of the transactions of the edinburgh r.s. concerning the general result of those observations, which will be given particularly in the course of this work.] it will thus appear, that the doctrine which of late has prevailed, of primitive mountains, or something which should be considered as original in the construction of this earth, must be given up as a false view of nature, which has formed the granite upon the same principle with that of any other consolidated stratum; so far as the collection of different materials, and the subsequent fusion of the compound mass, are necessary operations in the preparation of all the solid masses of the earth. whatever operations of the globe, therefore, may be concluded from the composition of granite masses, as well as of the alpine strata, these must be considered as giving us information with regard to the natural history of this earth; and they will be considered as important, in proportion as they disclose to us truths, which from other strata might not be so evident, or at all made known. let us now examine the arguments, which, may be employed in favour of that supposition of primitive mountains. the observations, on which naturalists have founded that opinion of originality in some of the component parts of our earth, are these; _first_, they observe certain great masses of granite in which stratification is not to be perceived; this then they say is an original mass, and it is not to be derived from any natural operation of the globe; _secondly_, they observe considerable tracts of the earth composed of matter in the order of stratification as to its general composition, but not as to its particular position, the vertical position here prevailing, instead of the horizontal which is proper to strata formed in water; this, therefore, they also term primitive, and suppose it to be from another origin than that of the subsidence of materials moved in the waters of the globe; _lastly_, they observe both strata and masses of calcareous matter in which they cannot distinguish any marine body as is usual in other strata of the same substance; and these calcareous masses being generally connected with their primitive mountains, they have also included these collections of calcareous matter, in which marine bodies are not observed, among the primitive parts which they suppose to be the original construction of this globe. it may be proper to see the description of a calcareous alpine mountain. m. de saussure gives us the following observations concerning a mountain of this kind in the middle of the alps, where the water divides in running different ways towards the sea. it is in describing the passage of the bon-homme, (tom. . v. dans les alpes). "§ . sur la droite ou au couchant de ces rochers, on voit une montagne calcaire étonnante dans ce genre par la hardiesse avec laquelle elle élève contre le ciel ses cimes aigues et tranchantes, taillées à angles vifs dans le costume des hautes cimes de granit. elle est pourtant bien sûrement calcaire, je l'ai observée de près, et on rencontre sur cette route les blocs qui s'en détachent. "cette pierre porte les caractères des calcaires les plus anciennes; sa couleur est grise, son grain assez fin, on n'y apperçoit aucun vestige de corps organisés; ses couches sont peu épaisses, ondées et coupées fréquemment par des fentes parallèles entr'elles et perpendiculaires à leurs plans. on trouve aussi parmi ces fragmens des brèches calcaires grises." here is a mountain which will rank with the most primitive of the earth; but why? only because it is extremely consolidated without any mark of organised body. had there been in this mountain but one single shell, we should not then have scrupled to conclude that the origin of this lofty mountain had been the same with every marble or limestone in the earth. but though, from the structure of this stone, there is no mark of its having been formed immediately of the calcareous parts of animals, there is every mark of those calcareous strata having been formed like other marbles by deposit in the waters of the globe. these two things are also homologated by the equal or perfect consolidation of their substance; for, as it is to be proved that all stratified marbles have been consolidated by the fusion of their substance, we must attribute the same consolidating cause to those alpine masses; the frequent veins that divide those calcareous strata which m. de saussure has here described, also prove the nature of the consolidating cause, (see chap. . page .). this mountain, considered by itself, may perhaps afford no data by which a naturalist might read the circumstances of its origin. but, is a theory of the earth to be formed upon such a negative observation? and, is there any particular in this mountain, that may not be shown in others of which the origin is not in any degree doubtful? it is not to be disputed, that there are parts of the solid body of our earth which may be considered as primary or prior, compared with others that are posterior, in relation to the time of their formation, and much less changed with regard to the state in which they had been originally formed:--but it is here denied, that there are any parts of the earth which do not appear to have had the same origin with all the rest, so far as this consists in the collection of materials deposited at the bottom of the waters[ ]; for there is no solid mass of land that may not be traced to this origin, either from its composition, or from its local connection with other masses, the nature of which in this respect are known. we have already given examples of this from sufficient authority. the evidence, therefore, of those primary masses being original in relation to the natural operations of the globe, is reduced to this assertion, that there are no vestiges of organised bodies to be found in those primary masses. let us now examine how far this testimony for the originality of those masses is to be admitted in fact and sound reasoning. [note : there are no collection of those alpine masses in which may not be found in some of them sand, mica, and gravel; but these materials prove the existence of an earth, on which those fragments of greater masses had been formed, and more or less worn by attrition.] the matter in question at present is this, that there are certain tracts of countries in which no vestige of organised bodies are found; now, let us suppose the fact to be true or well grounded, can we conclude from this that there had been originally no organised bodies in the composition of those masses?--such a conclusion could only be formed in making a supposition, that every organised body deposited in a mass of matter, whether homogeneous or heterogeneous, should be preserved without change, while the collected mass, in which it had been deposited, changes as much as possible by the operation both of fire and water. but this supposition is erroneous, and cannot be admitted; and the study of marbles will demonstrate this truth, that the calcareous relics of organised bodies are changed, in the consolidating operations of the globe, in every degree, from the smallest alteration to the greatest, when they become indistinguishable any farther to our sight. therefore, from the supposition of no appearance of marine bodies in the pretended primitive masses, there is no sufficient evidence or reason to conclude, that those masses have not had a marine origin; because, the traces of organised bodies may be obliterated by the many subsequent operations of the mineral region; and which operations, the present state of those masses certify beyond dispute. we are now to examine the fact, how far the ground on which that false reasoning had been founded is strictly true. in the first place, then, it must be considered, that the alledged fact is nothing but a negative assertion, importing that no mark of organised bodies had been observed, in certain stones and strata which some naturalists have examined with that view. but, though many naturalists have looked for them without success, it does not follow that such marks may not be found; it indeed proves that such a task is difficult, and the success of it, to a particular, most precarious; accident, however, may bring about what the greatest industry has not been able to attain. secondly, there is good reason to believe that this asserted negation is not absolutely true; for i have in my possession what i consider as proof of the contrary; i found it in wales, and i think it is in what may be considered as primitive mountains;--it is the mark of shells in a stone of that kind. thus, i had formed my opinion with regard to this alleged fact, long before i had seen any description either of the alps or pyrennean mountains; and now i have no reason to change that opinion. it may indeed be alleged, that the strata of marble or limestone, containing marine bodies found in those mountains, are secondary strata, and not the primitive. to this i can give no reply, as the descriptions given of those strata do not enable me to decide this point. at the village of mat, under the mont blatten for example, there is a quarry of schistus or black slate, in which are often found the print and the bones of fishes. (discours sur l'histoire naturelle de la suisse, page .). if this may be considered as an alpine or primitive schistus, it would be decisive of the question: but it would require to have it well ascertained that this schistus is truly one of those which are esteemed primitive, or that it is properly connected with them. but though i cannot find in those interesting descriptions which we now have got, any one which is demonstrative of this truth, that calcareous marine objects are found in the primitive strata, this is not the case with regard to another object equally important in deciding this question, whether the primitive strata are found containing the marks of organised bodies? m. de dellancourt, in his _observations minéralogiques_, journal de physique juillet , in describing the mountains of dauphiné, gives us the following fact with regard to those alpine vertical strata. "la pierre constituante de la montagne d'oris est en général le _kneifs_ ou la roche feuilletée mica et quartz à couches plus ou moins ferrées quelquefois le schorl en roche pénétré de stéatite. les couches varient infiniment quant à leur direction et à leur inclinaisons. cette montagne est cultivée et riche dans certain cantons, surtout autour du village d'oris, mais elle est très-escarpée dans beaucoup d'autres. entre le village d'oris et celui du tresnay est une espèce de combe assez creuse formée par la chute des eaux des cimes supérieures des rochers. cette combe offre beaucoup de schiste dont les couches font ou très-inclinées ou perpendiculaires. entre ces couches il s'en est trouvé de plus noires que les autres et capable de brûler, mais difficilement. les habitans ont extrait beaucoup de cette matière terreuse, et lui ont donné le nom de charbon de terre. ils viennent même à bout de la faire brûler, et de s'en servir l'hiver en la mêlant avec du bois. ce schiste noir particulier m'a paru exister principalement dans les endroits ou les eaux se sont infiltrées entre les couches perpendiculaires, et y ont entraîné diverse matières, et sur-tout des débris de végétaux que j'ai encore retrouvés à demi-noirs, pulvérulens et comme dans un état charbonneux." this formation of coal, by the infiltration of water and carrying in of vegetable bodies, certainly cannot be admitted of; consequently, from this description, there would seem to be strata of coal alternated with the alpine schisti. but the formation of mineral coal requires vegetable matter to have been deposited along with those earthy substances, at the bottom of the sea. the production of vegetable bodies, again, requires the constitution of sea and land, and the system of a living world, sustaining plants at least, if not animals. in this natural history of the alpine schisti, therefore, we have a most interesting fact, an example which is extremely rare. seldom are calcareous organised bodies found among those alpine strata, but still more rarely, i believe, are the marks of vegetable bodies having contributed in the formation of those masses. but however rare this example, it is equally decisive of the question, whether the alpine schisti have had a similar origin as the other strata of the globe, in which are found abundance of animal and vegetable bodies, or their relics? and we are authorised to say, that since those perfect alpine strata of dauphiné have had that origin, all the alpine schisti of the globe have been originally formed in a similar manner. but to put this matter out of doubt: in this summer , coming from the isle of man, mr clerk and i traveled through the alpine schistus country of cumberland and westmoreland. we found a limestone quarry upon the banks of windermere, near the low-wood inn. i examined this limestone closely, but despaired of finding any vestige of organised body. the strata of limestone seem to graduate into the slate or schistus strata, between which the calcareous are placed. fortunately, however, i at last found a fragment in which i thought to perceive the works of organised bodies in a sparry state; i told mr clerk so, and our landlord mr wright, who had accompanied us. i have brought home this specimen, which i have now ground and polished; and now it is most evidently full of fragments of entrochi. mr wright then told me he had seen evident impressions of marine objects, as i understood from the description, in the slate of those mountains; and he was to send me specimens so soon as he could procure them. here is one specimen which at once overturns all the speculations formed upon that negative proposition. the schistus mountains of cumberland were, in this respect, as perfect primitive mountains as any upon the earth, before this observation; now they have no claim upon that score, no more than any limestone formed of shells. when i first announced my belief that such objects in natural history might be found, i little thought to have seen it realised, to such a degree as has now happened in the little circle of my knowledge. in the summer , professor playfair was to pass through cumberland. i begged that he would inquire of mr wright, at the low-wood inn, for those objects which he was to endeavour to procure for me, and to examine the limestone quarry in which i had found the specimen with entrochi. he went through another part of those primary mountains, and has found examples of this kind in the schisti; concerning which he has written me the following account. "in a visit which i made to the lakes of cumberland in september , in company with the hon. francis charteris, i met with a limestone full of marine objects, though from its position it is certainly to be reckoned among the primary strata. the place where we found this stone was in the district of lancashire, that is west of windermere lake, on the road from ambleside to the north end of coniston lake, and not far from the point when you come in sight of the latter. just about this spot we happened to meet with one of those people who serve as guides to travelers in those parts, and who told us, among other things, that stones with shells in them were often found not far from where we were then walking. we immediately began to look about for specimens of that kind, and soon met with several; the most remarkable of which was in a rock that rose a little above the surface, about or yards to the right of the road. it was a part of a limestone stratum, nearly vertical, and was full of bivalves with the impressions as strong as in a common secondary limestone. the strata on both sides had the same inclination, and were decidedly primary, consisting of the ordinary micaceous schistus. this however i need not remark to you, who know so well from your own observations that the whole of the country i am now speaking of has every character of a primary one. i, only mention it, that it may not be supposed that the rock in question was some fragment of a secondary stratum that remained, after the rest was washed away, superincumbent on the primary. "after i had seen this rock, i recollected that you had told me of something of the same kind that you saw in a quarry at low-wood inn; and it may be that both belonged to the same stratum or body of strata; for the direction of the strata, as nearly as i could observe, was from s.w. to n.e.; and this also is nearly the bearing of low-wood from the place where we now were. i send you a specimen, which you can compare with those you brought from the lime quarry at low-wood." i have examined this specimen, and find it to be the common schistus of that country, only containing many bivalve shells and fragments of entrochi and madrapore bodies, and mixed with pyrites. i have already observed that one single example of a shell, or of its print, in a schistus, or in a stone stratified among those vertical or erected masses, suffices to prove the origin of those bodies to have been, what i had maintained them to be, water formed strata erected from the bottom of the sea, like every other consolidated stratum of the earth. but now, i think, i may affirm, that there is not, or rarely, any considerable extent of country of that primary kind, in which some mark of this origin will not be found, upon careful examination; and now i will give my reason for this assertion. i have been examining the south alpine country of scotland, occasionally, for more than forty years back, and i never could find any mark of an organised body in the schistus of those mountains. it is true that i know of only one place where limestone is found among the strata; this is upon tweed-side near the crook. this quarry i had carefully examined long ago, but could find no mark of any organised body in it. i suppose they now are working some other of the vertical strata near those which i had examined; for, in the summer , i received a letter from sir james hall, which i shall now transcribe. it is dated at moffat, june . . "as i was riding yesterday between noble-house and crook, on the road to this place, i fell in with a quarry of alpine limestone; it consists of four or five strata, about three feet thick, one of them single, and the rest contiguous; they all stand between the strata of slate and schist that are at the place nearly vertical. in the neighbourhood, a slate quarry is worked of a pure blue slate; several of the strata of slate near the limestone are filled with fragments of limestone scattered about like the fragments of schist in the sandstone in the neighbourhood of the junction on our coast.[ ] [note : this has a reference to very curious observations which we made upon the east coast where these mountains terminate, and which i am to describe in the course of this work.] "among the masses of limestone lately broken off for use, and having the fractures fresh, i found the forms of cockles quite distinct; and in great abundance.--i send you three pieces of this kind," etc. it may perhaps be alleged that those mountains of cumberland and tweedale are not the primary mountains, but composed of the secondary schistus, which is every where known to contain those objects belonging to a former earth. naturalists who have not the opportunity of convincing themselves by their proper examination, must judge with regard to that geological fact by the description of others. now it is most fortunate for natural history, that it has been in this range of mountains that we have discovered those marks of a marine origin; for, i shall afterwards have occasion to give the clearest light into this subject, from observations made in other parts of those same mountains of schist, by which it will be proved that they are the primary strata; and thus no manner of doubt will then remain in the minds of naturalists, who might otherwise suspect that we were deceiving ourselves, by mistaking the secondary for the primitive schistus. i have only farther to observe, that those schisti mountains of wales, of cumberland, and of the south alpine part of scotland, where these marine objects have been found, consist, of that species of stone which in some places makes the most admirable slate for covering houses; and, in other parts, it breaks into blocks that so much resemble wood in appearance, that, without narrow inspection, it might pass for petrified wood. we are therefore to conclude that the marks of organised bodies in those primary mountains are certainly found; at the same time the general observation of naturalists has some foundation, so far as the marks of organised bodies are both rarely to be met with in those masses, and not easily distinguished as such when they are found. but this scarcity of marine objects is not confined to those primary mountains, as they are called; for among the most horizontal strata, or those of the latest production, there are many in which, it is commonly thought, no marine calcareous objects are to be found; and this is a subject that deserves to be more particularly considered, as the theory may thus receive some illustration. sandstone, coal, and their accompanying strata, are thought to be destitute of calcareous marine productions, although many vestiges of plants or vegetable productions are there perceived. but this general opinion is neither accurate nor true; for though it be true that in the coal and sandstone strata it is most common to find marks of vegetable production, and rarely those calcareous bodies which are so frequent in the limestone, yet it is not unusual for coal to be accompanied with limestone formed of shells and corals, and also with ironstone containing many of those marine objects as well as wood. besides, sandstone frequently contains objects which have been organised bodies, but which do not belong to the vegetable kingdom, at least to no plant which grows upon the land, but would seem to have been some species of zoophite perhaps unknown. i have also frequently seen the vestige of shells in sandstone, although in these strata the calcareous bodies are in general not perceived. the reason of this is evident. when there is a small proportion of the calcareous matter in the mass of sand which is pervious to steam and to the percolation of water, the calcareous bodies may be easily dissolved, and either carried away or dispersed in the mass; or even without being thus dispersed by means of solution, the calcareous matter may be absorbed by the siliceous substance of the stratum by means of fusion, or by heat and cementation. the fact is, that i have seen in sandstone the empty mould of marine shells with some siliceous crystallization, so far as i remember, which corresponded perfectly with that idea. the place i saw this was in a fine white sandstone accompanying the coal, upon the sea side at brora in sutherland. mineralogy is much indebted to mr pallas for the valuable observations which he has given of countries so distant from the habitations of learned men. the physiology of the globe has also been enriched with some interesting observations from the labours of this learned traveller. but besides giving us facts, mr pallas has also reasoned upon the subject, and thus entered deep into the science of cosmogeny; here it is that i am afraid he has introduced some confusion into the natural history of the earth, in not properly distinguishing the mineral operations of the globe, and those again which belong entirely to the surface of the earth; perhaps also in confounding the natural effects of water upon the surface of the earth, with those convulsions of the sea which may be properly considered as the accidental operations of the globe. this subject being strictly connected with the opinions of that philosopher with regard to primitive mountains, i am obliged to examine in this place matters which otherwise might have come more properly to be considered in another. m. pallas in his _observations sur la formation des montagnes_, (page ) makes the following observations. "j'ai déjà dit que _la bande de montagnes primitives schisteuses_ hétérogènes, qui, par toute la terre, accompagne les chaînes granitiques, et comprend les roches quartzeuses et talceuses mixtes, trapézoïdes, serpentines, le schiste corne, les roches spathiques et cornées, les grais purs, le porphyre et le jaspre, tous rocs fêlés en couches, ou presque perpendiculaires, ou du moins très-rapidement inclinées, (les plus favorables à la filtration des eaux), semble aussi-bien que le granit, antérieure à la création organisée. une raison très-forte pour appuyer cette supposition, c'est que la plupart de ces roches, quoique lamelleuse en façon d'ardoise, n'a jamais produit aux curieux la moindre trace de pétrifactions ou empreintes de corps organisés. s'il s'en est trouvé, c'est apparemment dans des fentes de ces roches où ces corps ont été apportés par un deluge, et encastrées apres dans une matière infiltrée, de même qu'on a trouvé des restes d'eléphans dans le filon de la mine d'argent du schlangenberg.[ ] les caractères par lesquels plusieurs de ces roches semblent avoir souffert des effets d'un feu-très-violent, les puissantes veines et amas des minéraux les plus riches qui se trouvent principalement dans la bande qui en est composée, leur position immédiate sur le granit, et même le passage, par lequel on voit souvent en grand, changer le granit en une des autres espèces; tout cela indique une origine bien plus ancienne, et des causes bien différentes de celles qui ont produit les montagnes secondaires." [note : this is a very natural way of reasoning when a philosopher finds a fact, related by some naturalists, that does not correspond with his theory or systematic view of things. here our author follows the general opinion in concluding that no organised body should be found in their primitive strata; when, therefore, such an object is said to have been observed, it is supposed that there may have been some mistake with regard to the case, and that all the circumstances may not have been considered. this caution with regard to the inaccurate representation of facts, in natural history, is certainly extremely necessary; the relicts of an elephant found in a mineral vein, is certainly a fact of that kind, which should not be given as an example in geology without the most accurate scientifical examination of the subject.] here m. pallas gives his reason for supposing those mountains primitive or anterior to the operations of this globe as a living world; _first_, because they have not, in general, marks of animals or plants; and that it is doubtful if they ever properly contain those marks of organised bodies; _secondly_, because many of those rocks have the appearance of having suffered the effects of the most violent fire. now, what are those effects? is it in their having been brought into a fluid state of fusion. in that case, no doubt, they may have been much changed from the original state of their formation; but this is a very good reason why, in this changed state, the marks of organised bodies, which may have been in their original constitution, should be now effaced. the _third_ reason for supposing those mountains primitive, is taken from the metallic veins, which are found so plentifully in these masses. now, had these masses been the only bodies in this earth in which those mineral veins were found, there might be some species of reason for drawing the conclusion, which is here formed by our philosopher. but nothing is so common (at least in england) as mineral veins in the strata of the latest formation, and in those which are principally formed of marine productions; consequently so far from serving the purpose for which this argument was employed, the mineral veins in the primitive mountains tend to destroy their originality, by assimilating them in some respect with every other mass of strata or mountain upon the globe. _lastly_, m. pallas here employs an argument taken from an appearance for which we are particularly indebted to him, and by which the arguments which have been already employed in denying the originality of granite is abundantly confirmed. it has been already alleged, that granite, porphyry, and whinstone, or trap, graduate into each other; but here m. pallas informs us that he has found the granite not only changed into porphyry, but also into the other alpine compositions. how an argument for the originality of these mountains can be established upon those facts, i am not a little at a loss to conceive. the general mineralogical view of the russian dominions, which we have, in this treatise, may now be considered with regard to that distinction made by naturalists, of primitive, secondary, and tertiary mountains, in order to see how far the observations of this well informed naturalist shall be found to confirm the theory of the earth which has been already given, or not. the oural mountains form a very long chain, which makes the natural division betwixt europe and asia, to the north of the caspian. if in this ridge, as a centre of elevation, and of mineral operations, we shall find the greatest manifestation of the violent exertion of subterraneous fire, or of consolidating and elevating operations; and if we shall perceive a regular appearance of diminution in the violence or magnitude of those operations, as the places gradually recede from this centre of active force; we may find some explanation of those appearances, without having recourse to conjectures which carry no scientific meaning, and which are more calculated to confound our acquired knowledge, than to form any valuable distinction of things. let us consult m. pallas how far this is the case, or not. after having told us that all those various alpine schisti, jaspers, porphyries, serpentines, etc. in those mountains, are found mutually convertible with granite, or graduating into each other, our author thus continues, (p. ). "on entrevoit de certaines loix a l'égard de l'arrangement respectif de cet ordre secondaire d'anciennes roches, par tous les systèmes de montagnes qui appartiennent à l'empire russe. la chaîne ouralique, par exemple, a du côté de l'orient sur tout sa longueur, une très-grande abondance de schistes cornés, serpentins et talceux, riches en filons de cuivre, qui forment le principal accompagnement du granite, et en jaspres de diverses couleurs plus extérieurs et souvent comme entrelacés avec les premiers, mais formant des suites de montagnes entières, et occupant de très-grands espaces. de ce même côté, il y paraît beaucoup de quartz en grandes roches toutes pures, tant dans la principale chaîne que dans le noyau des montagnes de jaspre, et jusques dans la plaine. les marbres spateux et veinés, percent en beaucoup d'endroits. la plupart de ces espèces ne paraissent point du tout à la lisière occidentale de la chaîne, qui n'est presque que de roche mélangée de schistes argileux, alumineux, phlogistique, etc. les filons des mines d'or mêlées, les riches mines de cuivre en veines et chambrées, les mines de fer et d'aimant par amas et montagnes entières, sont l'apanage de la bande schisteuse orientale; tandis que l'occidentale n'a pour elle que des mines de fer de dépôts, et se montre généralement très-pauvre en métaux. le granit de la chaîne qui borde la sibérie, est recouvert du côté que nous connaissons de roches cornées de la nature des pierres à fusil, quelquefois tendant à la nature d'un grais fin et de schistes très-métallières de différente composition. le jaspre n'y est qu'en filons, ou plans obliques, ce qui est très-rare pour la chaîne ouralique, et s'observe dans la plus grande partie de la sibérie, à l'exception de cette partie de sa chaîne qui passe près de la mer d'okhotsk, ou le jaspre forme derechef des suites de montagnes, ainsi que nous venons de le dire des monts ourals; mais comme cette roche tient ici le côté méridionale de la chaîne sibérienne, et que nous ne lui connaissons point ce côté sur le reste de sa longueur, il se pourrait que le jaspre y fût aussi abondant. il faudrait, au reste, bien plus de fouilles et d observations pour établir quelque chose de certain sur l'ordre respectif qu'observent ces roches." i would now ask, if in all this account of the gradation of rock from the oural mountains to the sandy coast of the baltic, there is to be observed any clear and distinctive mark of primitive, secondary, and tertiary, mountains, farther than as one stratum may be considered as either prior or posterior to another stratum, according to the order of superposition in which they are found. we have every where evident marks of the formation of strata by materials deposited originally in water; for the most part, there is sufficient proof that this water in which those materials had been deposited was the sea; we are likewise assured that the operations of this living world producing animals, must have, for a course of time, altogether inconceivably been exerted, in preparing materials for this mass; and, lastly, from the changed constitution of those masses, we may infer certain mineral operations that melt the substance and alter the position of those horizontal bodies. such is the information which we may collect from this mineral description of the russian dominions. if we compare some of the oural mountains with the general strata of the russian plains, then, as to the contained minerals, we may find a certain diversity in those two places; at the same time, no greater perhaps than may be found betwixt two different bodies in those same plains, for example, chalk and flint. but when we consider those bodies of the earth, or solid strata of the globe, in relation to their proper structure and formation, we surely can find in this description nothing on which may be founded any solid opinion with regard to a different original, however important conclusions may perhaps be formed with regard to the operations of the globe, from the peculiar appearances found in alpine. from this detail of what is found in the oural mountains, and in the gradation of country from those mountains to the plains of russia, we have several facts that are worthy of observation. first extensive mountains of jasper. i have a specimen of this stone; it is striped red and green like some of our marly strata. it has evidently been formed of such argillaceous and siliceous materials, not only indurated, so as to lose its character, as an argillaceous stone, but to have been brought into that degree of fusion which produces perfect solidity. of the same kind are those hornstein rocks of the nature of flint, sometimes tending to the nature of a fine sandstone. here is the same induration of sandstone by means of fusion, that in the argillaceous strata has produced jasper. but oblique veins of jasper are represented as traversing these last strata; now this is a fact which is not conceivable in any other way, than by the injection or transfusion of the fluid jasper among those masses of indurated strata. all this belongs to the east side of the mountains. on the west, again, we find the same species of strata; only these are not changed to such a degree as to lose their original character or construction, and thus to be termed differently in mineralogy. our author then proceeds. (p. .) "nous pourrons parler plus décisivement sur les _montagnes secondaires et tertiaires_ de l'empire, et c'est de celles-là, de la nature, de l'arrangement et du contenu de leurs couches, des grandes inégalités et de la forme du continent d'europe et d'asie, que l'on peut tirer avec plus de confiance quelques lumières sur les changemens arrivés aux terres habitables. ces deux ordres de montagnes présentent la chronique de notre globe la plus ancienne, la moins sujette aux falsifications, et en même-tems plus lisible que le caractère des chaînes primitives; ce font les archives de la nature, antérieures aux lettres et aux traditions les plus reculées, qu'il étoit réservé à notre siècle observateur de feuiller, de commenter, et de mettre au jour, mais que plusieurs siècles après le nôtre n'épuiseront pas. "dans toute l'étendue de vastes dominations russes, aussi bien que dans l'europe entière, les observateurs attentifs ont remarqué que généralement la band schisteuse des grandes chaînes se trouve immédiatement recouverte ou cottée par la _bande calcaire_. celle-ci forme deux ordres de montagnes, très-différentes par la hauteur, la situation de leurs couches, et la composition de la pierre calcaire qui les compose; différence qui est très-évidente dans cette bande calcaire qui forme la lisière occidentale de toute la chaîne ouralique, et dont le plan s'étend par tout le plat pays de la russie. l'on observerait la même chose à l'orient de la chaîne, et dans toute l'étendue de la sibérie, si les couches calcaires horizontales n'y étaient recouvertes par les dépôts postérieures, de façon qu'il ne paraît à la surface que les parties les plus faillantes de la bande, et si ce pays n'étoit trop nouvellement cultivé et trop peu exploité par des fouilles et autres opérations, que des hommes industrieux ont pratiqué dans les pays anciennement habités. ce que je vais exposer sur les deux ordres de montagnes calcaires, se rapportera donc principalement à celles qui sont à l'occident de la chaîne ouralique. "ce côté de la dite chaîne consiste sur cinquante à cent verstes de largeur, de roche calcaire solide, d'un grain uni, qui tantôt ne contient aucune trace de productions marines, tantôt n'en conserve que des empreintes aussi légères qu'éparses. cette roche s'élève en montagnes d'une hauteur très-considérable, irrégulières, rapides, et coupées de vallons escarpés. ses couches, généralement épaisses, ne sont point de niveau, mais très-inclinées à l'horizon, paralleles, pour la plupart, à la direction de la chaîne, qui est aussi ordinairement celle de la bande schisteuse;--au lieu que du côté de l'orient les couches calcaires sont au sens de la chaîne en direction plus ou moins approchante de l'angle droite. l'on trouve dans ces hautes montagnes calcaires de fréquentes grottes et cavernes très-remarquables, tant par leur grandeur que par les belles congélations et crystallizations stalactiques dont elles s'ornent. quelques-unes de ces grottes ne peuvent être attribuées qu'à quelque bouleversement des couches; d'autres semblent devoir leur origine à l'écoulement des sources souterraines qui ont amolli, rongé et charrié une partie de la roche qui en étoit susceptible. "en s'éloignant de la chaîne, on voit les couches calcaires s'aplanir assez rapidement, prendre une position horizontale, et devenir abondantes en toute forte de coquillages, de madrépores, et d'autres dépouilles marines. telles on les voit par-tout dans les vallées les plus basses qui se trouvent aux pieds des montagnes (comme aux environs de la rivière d'oufa); telles aussi, elles occupent tout l'étendue de la grande russie, tant en collines qu'en plat pays; solides tantôt et comme semées de productions marines; tantôt toutes composées de coquilles et madrépores brisées, et de ce gravier calcaire qui se trouve toujours sur les parages ou la mer abonde en pareilles productions; tantôt, enfin, dissoutes en craie et en marines, et souvent entremêlées de couches de gravier et de cailloux roulés." how valuable for science to have naturalists who can distinguish properly what they see, and describe intelligibly that which they distinguish. in this description of the strata, from the chain of mountains here considered as primitive, to the plains of russia, which are supposed to be of a tertiary formation, our naturalist presents us with another species of strata, which he has distinguished, on the one hand, in relation to the mountains at present in question, and on the other, with regard to the strata in the plains, concerning which there is at present no question at all. now, let us see how these three things are so connected in their nature, as to form properly the contiguous links of the same chain. the primary and tertiary masses are bodies perfectly disconnected; and, without a medium by which they might be approached, they would be considered as things differing in all respects, consequently as having their origins of as opposite a nature as are their appearances. but the nature and formation of those bodies are not left in this obscurity; for, the secondary masses, which are interposed, participate so precisely of what is truly opposite and characteristic in the primary and tertiary masses, that it requires nothing more than to see this distinction of things in its true light, to be persuaded, that in those three different things we may perceive a certain gradation, which here takes place among the works of nature, and forms three steps distinguishable by a naturalist, although in reality nothing but the variable measure of similar operations. we are now to assimilate the primary and tertiary masses, which are so extremely different, by means of the secondary masses, which is the mean. the primary and tertiary differ in the following respects: the one of these contains the relicts of organised bodies which are not observed in the other. but in the species containing these distinguishable bodies, the natural structure and position of the mass is little affected, or not so much as to be called into doubt. this, however, is not the case with the other; the species in which organised bodies do not appear, is in general so indurated or consolidated in its structure, and changed in its position, that this common origin of those masses is by good naturalists, who have also carefully examined them, actually denied. now, the secondary masses may be considered, not only as intermediate with respect to its actual place, as m. pallas has represented it, but as uniting together the primary and tertiary, or as participating of the distinguishing characters of the other two. it is homologated with the primitive mountains, in the solidity of its substance and in the position of its strata; with the tertiary species, again, in its containing marks of organised bodies. how far this view of things is consistent with the theory of the earth now given, is submitted to the consideration of the unprejudiced. let us see what our learned author has said farther on this subject, (page ). "je dois parler d'un ordre de montagnes très-certainement postérieur aux couches marines, puisque celles-ci, généralement lui servent de base. on n'a point jusqu'ici observé une suite de ces _montagnes tertiaires_, effet des catastrophes les plus modernes de notre globe, si marquée et si puissante, que celle qui accompagne la chaine ouralique ou côté occidentale fur tout la longueur. cette suite de montagnes, pour la plupart composées de grais, de marnes rougeâtres, entremêlées de couches diversement mixtes, forme une chaîne par-tout séparée par une vallée plus ou moins large de la bande de roche calcaire, dont nous avons parlé. sillonnée et entrecoupée de fréquens vallons, elles s'élève souvent à plus de cent toises perpendiculaires, se répand vers les plaines de la russie en traînées de collines, qui séparent les rivières, en accompagnant généralement la rive boréale ou occidentale, et dégénère enfin en déserts sableux qui occupent de grands espaces, et s'étendent surtout par longues bandes parallèles aux principales traces qui suivent les cours des rivieres. la principale force de ces montagnes tertiaires est plus près de la chaîne primitive par-tout le gouvernement d'orenbourg et la permie, ou elle consiste principalement en grais, et contient un fond inépuisable de mines de cuivre sableuses, argileuses, et autres qui se voient ordinairement dans les couches horizontales. plus loin, vers la plaine, sont des suites de collines toutes marneuses, qui abondent autant en pierres gypseuses, que les autres en minerais cuivreux. je n'entre pas dans le détail de celles-ci, qui indiquent sur-tout les sources salines; mais je dois dire des premières, qui abondent le plus et dont les plus hautes élévations des plaines, même celle de moscou, sont formées, qu'elles contiennent très-peu de traces de productions marines, et jamais des amas entiers de ces corps, tels qu'une mer reposée pendant des siècles de suite a pu les accumuler dans les bancs calcaires. rien, au contraire, de plus abondant dans ces montagnes de grais stratifié sur l'ancien plan calcaire, que des troncs d'arbres entières et des fragmens de bois pétrifié, souvent minéralisé par le cuivre ou le fer; des impressions de troncs de palmires, de tiges de plantes, de roseau, et de quelques fruits étrangers; enfin des ossemens d'animaux terrestres, si rares dans les couches calcaires. les bois pétrifiés se trouvent jusques dans les collines de sable de la plaine; l'on en tire, entr'autres, des hauteurs sablonneuses aux environs de sysran sur la volga, changés en queux très-fin, qui a conservé jusqu'à la texture organique du bois, et remarquables sur-tout par les traces très-évidentes de ces vers rongeurs qui attaquent les vaisseaux, les pilotis et autres bois trempés dans la mer, et qui sont proprement originaires de la mer des indes." this philosopher has now given us a view of what, according to the present fashion of mineral philosophy, he has termed _montagnes primitives, secondaires, et tertiaires_. the first consists in masses and strata, much indurated and consolidated, and greatly displaced in their position; but the character of which is chiefly taken from this, that they contain not any visible mark of animal or vegetable bodies. the second are formed in a great measure of marine productions, are often no less consolidated than those of the first class, and frequently no less changed in their natural shape and situation. the third again have for character, according to this learned theorist, the containing of those organised bodies which are proper to the earth, instead of those which in the second class had belonged to the sea; in other respects, surely there is no essential difference. it is not pretended that these tertiary strata had any other origin, than that of having been deposited in water; it is not so much as suspected, that this water had been any other than that of the sea; the few marine bodies which m. pallas here acknowledges, goes at least to prove this fact: and with regard to the mineral operations which had been employed in consolidating those water formed strata, it is impossible not to be convinced that every effect visible in the other two are here also to be perceived. from this view of mineral bodies, taken from the extensive observations of the russian dominions, and from the suppositions of geologists in relation to those appearances, we should be led to conclude that the globe of this earth had been originally nothing but an ocean, a world containing neither plant nor animal to live, to grow and propagate its species. in following a system founded on those appearances, we must next suppose, that to the sterile unorganised world there had succeeded an ocean stored with fish of every species. here it would be proper to inquire what sustained those aquatic animals; for, in such a system as this, there is no provision made for continuing the life even of the individuals, far less of feeding the species while, in an almost infinite succession of individuals, they should form a continent of land almost composed of their _exuviae_. if fish can be fed upon water and stone; if siliceous bodies can, by the digesting powers of animals, be converted into argillaceous and calcareous earths; and if inflammable matter can be prepared without the intervention of vegetable bodies, we might erect a system in which this should be the natural order of things. but to form a system in direct opposition to every order of nature that we know, merely because we may suppose another order of things different from the laws of nature which we observe, would be as inconsistent with the rules of reasoning in science, by which the speculations of philosophy are directed, as it would be contrary to common sense, by which the affairs of mankind are conducted. still, however, to pursue our visionary system, after a continent had been formed from the relicts of those animals, living, growing, and propagating, during an indefinite series of ages, plants at last are formed; and, what is no less wonderful, those animals which had formed the earth then disappear; but, in compensation, we are to suppose, i presume, that terrestrial animals began. let us now reason from those facts, without either constraining nature, which we know, or forming visionary systems, with regard to things which are unknown. it would appear, that at one period of time, or in one place, the matter of the globe may be deposited, in strata, without containing any organised bodies; at another time, or in another place, much animal matter may be deposited in strata, without any vegetable substance there appearing; but at another period, or at another time, strata may be formed with much vegetable matter, while there is hardly to be observed any animal body. what then are we to conclude upon the whole? that nature, forming strata, is subject to vicissitudes; and that it is not always the same regular operation with respect to the materials, although always forming strata upon the same principles. consequently, upon the same spot in the sea, different materials may be accumulated at different periods of time, and, conversely, the same or similar materials may be collected in different places at the same time. nothing more follows strictly from the facts on which we now are reasoning; and this is a conclusion which will be verified by every appearance, so far as i know. of this i am certain, that in a very little space of this country, in many places, such a course of things is to be perceived. nothing so common as to find alternated, over and over again, beds of sand-stone without animal bodies, beds of coal and schistus abounding with vegetable bodies, beds of lime-stone formed of shells and corals, and beds or particular strata of iron-stone containing sometimes vegetable sometimes animal bodies, or both. here, indeed, the strata are most commonly inclined; it is seldom they are horizontal; consequently, as across the whole country, all the strata come up to the day, and may be seen in the beds of our rivers, we have an opportunity of observing that great variety which is in nature, and which we are not able to explain. this only is certain, from what we see, that there is nothing formed in one epoch of nature, but what has been repeated in another, however dissimilar may be the operations which had intervened between those several epochs. it must not be alleged, that the heights of the oural mountains, or the hardness of their rocks, make an essential distinction between them and the argillaceous or arenaceous strata of the plains; solidity and hardness, as well as changes in their height and natural position, has been superinduced in operations posterior to the collection of those masses,--operations which may be formed in various degrees, even in the different parts of the same mass. if this is the case, there can be no difficulty in conceiving a stratum, which appears to be argillaceous or marly in the plains, to be found jasper in the oural mountains. but there is nothing in the oural mountains, that may not be found some where or other in the plains, although the soft and easily decomposing argillaceous strata be not found upon the oural mountains, or the alps, for this reason, that had those mountains been formed of such materials, there had not been a mountain there at this day. but surely the greatest possible error, with regard to the philosophy of this earth, would be to confound the sediment of a river with the strata of the globe; bodies deposited upon the surface of the earth, with those sunk at the bottom of the sea; and things which only form the travelled or transported soil, with those which constitute the substratum or the solid earth. how far m. pallas has committed this oversight, i leave others to determine. after mentioning those strata in which wood is found petrified, and metallic minerals formed, he thus proceeds, (page ). "dans ces mêmes dépôts sableux et souvent limoneux, gisent les restes des grands animaux de l'inde: ces ossemens d'éléphans, de rhinocéros, de buffles monstrueux, dont on déterre tous les jours un si grand nombre, et qui font l'admiration des curieux. en sibérie, où l'on à découvert le long de presque toutes les rivières ces restes d'animaux étrangers, et l'ivoire même bien conservé en si grande abondance, qu'il forme un article de commerce, en sibérie, dis je, c'est aussi la couche la plus moderne de limon sablonneux qui leur sert de sépulture, et nulle part ces monumens étrangers sont si frequens, qu'aux endroits où la grande chaine, qui domine surtout la frontière méridionale de la sibérie, offre quelque dépression, quelque ouverture considérable. "ces grands ossemens, tantôt épars tantôt entassés par squelettes, et même par hécatombes, considérée dans leurs sites naturels, m'ont sur-tout convaincu de la réalité d'un déluge arrivé sur notre terre, d'une catastrophe, dont j'avoue n'avoir pu concevoir la vraisemblance avant d'avoir parcouru ces places, et vu, par moi-même, tout ce qui peut y servir de preuve à cet évènement mémorable[ ]. une infinité de ces ossemens couchés dans des lits mêlés de petites tellines calcinées, d'os de poissons, de glossopètres, de bois chargés d'ocre, etc. prouve déjà qu'ils ont été transportés par des inondations. mais la carcasse d'un rhinocéros, trouvé avec sa peau entière, des restes de tendons, de ligamens, et de cartilages, dans les terres glacées des bords du viloûi, dont j'ai déposé les parties les mieux conservées au cabinet de l'académie, forme encore une preuve convaincante que ce devait être un mouvement d'inondation des plus violens et des plus rapides, qui entraîna jadis ces cadavres vers nos climats glacés, avant que la corruption eût le tems, d'en détruire les parties molles. il seroit à souhaiter qu'un observateur parvint aux montagnes qui occupent l'espace entre les fleuves indighirka et koylma où selon le rapport des chasseurs, de semblables carcasses d'éléphans et d'autres animaux gigantesques encore revêtues de leurs peaux, ont été remarquées à plusieurs reprises." [note : voyez le mémoire, imprimé dans le xvii. volume des nouveaux commentaires de l'académie imperiale de petersbourgh.] the question here turns upon this, are the sea shells and glossopetrae, which are thus found deposited along with those skeletons, in their natural state, or are they petrified and mineralised. if the productions of the sea shall here be found collected along with bodies belonging to the surface of the earth, and which had never been within the limits of the sea, this would surely announce to us some strange catastrophe, of which it would be difficult, perhaps, to form a notion; if, on the contrary, those marine productions belong to the solid strata of the earth, in the resolution or decay of which they had been set at liberty, and were transported in the floods, our author would have no reason from those appearances to conclude, there had existed any other deluge than those produced by the waters of the land[ ]. [note : since writing this, i find my doubts in a great measure resolved, in reading m. pallas's journal, translated from the german by m. gauthier de la peyronie. what i had suspected is, i think, confirmed in the distinct account which m. pallas has given of those occasions in which the bones of land animals and marine objects are found buried together. the marine objects are mineralised; consequently, they have proceeded from the decomposition of the solid strata; and, having been travelled in the running water of the surface of the earth, they must have been deposited in those beds of rivers, which now are dry, alongst with the bones, or the entire bodies of terrestrial animals, the remains of which are now found there. this argument, from the state of those marine bodies will not be allowed, perhaps by the generality of mineralists, who attribute to the operations of water every species of petrifaction or mineralisation; but, until some species of proof be given with regard to the truth of that theory, which vulgar error first suggested, i must reason from a theory, in proof of which i have given clear examples, and, i think, irrefragable arguments, which shall be more and more illustrated. thus may be removed the necessity of a general deluge, or any great catastrophe, in order to bring together things so foreign to each other; but at the same time we would ascertain this fact, that formerly the elephant and rhinoceros had lived in siberia. (see voyage de pallas, tom. ii. p. and .)] having thus endeavoured to remove this prevailing prejudice, of there being primitive parts in this earth, parts of which the composition and constitution are not to be explained upon the principles of natural philosophy, it will be proper to inquire, how far there may be in the theory, which has now been given, principles by which may be explained those appearances that have led natural philosophers to form conclusions, of there being in this earth parts whose origin may not be traced; and of there being parts whose origin may not be explained upon the same principles which apply so well to all the rest. chap. v. concerning that which may be termed the primary part of the present earth. in the present theory, it is maintained, that there is no part of the earth which has not had the same origin, so far as this consists in that earth being collected at the bottom of the sea, and afterwards produced, as land, along with masses of melted substances, by the operation of mineral causes. but, though all those things be similar, or equal, as to the manner of their production, they are far from being so with regard to the periods of their original composition, or to the subsequent operations which they may have undergone. there is a certain order established for the progress of nature, for the succession of things, and for the circulation of matter upon the surface of this globe; and, the order of time is associated with this change of things. but it is not in equal portions that time is thus combined with dissimilar things, nor always found, in our estimation, as equally accompanying those which we reckon similar. the succession of light and darkness is that which, in those operations, appears to us most steady; the alternation of heat and cold comes next, but not with equal regularity in its periods. the succession of wet and dry upon the surface of the earth, though equally the work of nature and the effect of regular causes, is often to us irregular, when we look for equal periods in the course of things which are unequal. it is by equalities that we find order in things, and we wish to find order every where. the present object of our contemplation is the alternation of land and water upon the surface of this globe. it is only in knowing this succession of things, that natural appearances can be explained; and it is only from the examination of those appearances, that any certain knowledge of this operation is to be obtained. but how shall we acquire the knowledge of a system calculated for millions, not of years only, nor of the ages of man, but of the races of men, and the successions of empires? there is no question here with regard to the memory of man, of any human record, which continues the memory of man from age to age; we must read the transactions of time past, in the present state of natural bodies; and, for the reading of this character, we have nothing but the laws of nature, established in the science of man by his inductive reasoning. it has been in reasoning after this manner, that i have endeavoured to prove, that every thing which we now behold, of the solid parts of this earth, had been formerly at the bottom of the sea; and that there is, in the constitution of this globe, a power for interchanging sea and land. if this shall be admitted as a just view of the system of this globe, we may next examine, how far there are to be found any marks of certain parts of our earth having more than once undergone that change of posture, or vicissitude of things, and of having had reiterated operations of the mineral kingdom changing their substance, as well as altering their positions in relation to the atmosphere and sea. besides the gradual decay of solid land, exposed to the silent influences of the atmosphere, and to the violent operations of the waters moving upon the surface of the earth, there is a more sudden destruction that may be supposed to happen sometimes to our continents of land. in order to see this, it must be considered, that the continents of our earth are only raised above the level of the sea by the expansion of matter, placed below that land, and rarified in that place: we may thus consider our land as placed upon pillars, which may break, and thus restore the ancient situation of things when this land had been originally collected at the bottom of the ocean. it is not here inquired by what mechanism this operation is to be performed; it is certainly by the exertion of a subterranean power that the land is elevated from the place in which it had been formed; and nothing is more natural than to suppose the supports of the land in time to fail, or be destroyed in the course of mineral operations which are to us unknown. in that case, whatever were remaining of that land, which had for millions of ages past sustained plants and animals, would again be placed at the bottom of the sea; and strata of every different species might be deposited again upon that mass, which, from an atmospheric situation, is now supposed to be lower than the surface of the sea. such a compound mass might be again resuscitated, or restored with the new superincumbent strata, consolidated in their texture and inclined in their position. in that case, the inferior mass must have undergone a double course of mineral changes and displacement; consequently, the effect of subterranean heat or fusion must be more apparent in this mass, and the marks of its original formation more and more obliterated. if, in examining our land, we shall find a mass of matter which had been evidently formed originally in the ordinary manner of stratification, but which is now extremely distorted in its structure, and displaced in its position,--which is also extremely consolidated in its mass, and variously changed in its composition,--which therefore has the marks of its original or marine composition extremely obliterated, and many subsequent veins of melted mineral matter interjected; we should then reason to suppose that here were masses of matter which, though not different in their origin from those that are gradually deposited at the bottom of the ocean, have been more acted upon by subterranean heat and the expanding power, that is to say, have been changed in a greater degree by the operations of the mineral region. if this conclusion shall be thought reasonable, then here is an explanation of all the peculiar appearances of the alpine schistus masses of our land, those parts which have been erroneously considered as primitive in the constitution of the earth. we are thus led to suppose, that some parts of our earth may have undergone the vicissitudes of sea and land more than once, having been changed from the summit of a continent to the bottom of the sea, and again erected, with the rest of that bottom, into the place of land. in that case, appearances might be found to induce natural philosophers to conclude that there were in our land primary parts, which had not the marine origin which is generally to be acknowledged in the structure of this earth; and, by finding other masses, of marine origin, superincumbent upon those primary mountains, they might make strange suppositions in order to explain those natural appearances. let us now see what has been advanced by those philosophers who, though they term these parts of the earth _primordial_, and not _primitive_, at the same time appear to deny to those parts an origin analogous to that of their secondary mountains, or strata that are aquiform in their construction. m. de luc, after having long believed that the strata of the alps had been formed like those of the low countries, at the bottom of the sea, gives an account of the occasion by which he was first confirmed in the opposite opinion.[ ] like a true philosopher, he gives us the reason of this change. [note : lettres physique et morales sur l'histoire de la terre, tom. . pag. .] "ce fut une espèce de _montagne_ très commune, et que j'avois souvent examinée qui dessilla mes yeux. la pierre qui la compose est de la classe appellée _schiste_; son caractère générique est d'être _feuilletée_; elle renferme _l'ardoise_ dont on couvre les toits. ces _feuillets_ minces, qu'on peut prendre pour des _couches_, et qui le font en effet dans quelques pierres de ce genre, rappelloient toujours l'idée vague de dépôts des eaux. mais il y a des masses dont la composition est plutôt par fibres que par feuillets, et dont le moëllon ressemble aux copeaux de bois d'un chantier. le plus souvent aussi les feuillets sont situés en toute suite de sens dans une même _montagne_, et quelquefois même verticalement, enfin il s'en trouve de si tortillés, qu'il est impossible de les regarder comme des dépôts de l'eau. "ce fut donc cette espèce de montagne qui me persuada la première que toutes les montagnes n'avoient pas une même origine. le lieu où j'abjurai mon erreur, étoit un de ces grands _chantiers_ pétrifiés, qui, par la variété du tortillement, et des zig-zags des fibres du moëllon qui le composoit, attira singulièrement mon attention. c'étoit un sort grand talus qui venoit d'une face escarpée; j'y montai pour m'approcher du rocher, et je remarquai, avec étonnement, des multitudes de paquets enchevêtrés les uns dans les autres, sans ordre ni direction fixe; les uns presqu'en rouleaux; les autres en zig-zag; et même ce qui, séparé de la montagne, eût peu être pris pour des _couches_, le trouvoit incliné de toute manière dans cette même face de rocher. _non_, me dis-je alors à moi-même; _non, l'eau n'a pu faire cette montagne.... ni celle-là donc_, ajoutai-je en regardant ailleurs.... _et pourquoi mieux celle-là? pourquoi toutes les montagnes devroient-elles être le produit des eaux, seulement parce qu'il y en a quelques-unes qui annoncent cette origine_? en effet, puis qu'on n'a songé aux eaux, comme cause des montagnes, que par les preuves évidentes que quelques-unes offroient de cette formation; pourquoi étendre cette conséquence à toutes, s'il y en a beaucoup qui manquent de ces caractères? c'est comme le dit mr. d'alembert, qu'on généralise ses premières remarques l'instant d'apres qu'on ne remarquoit rien." science is indebted to this author for giving us so clear a picture of natural appearances, and of his own reasoning upon those facts, in forming his opinion; he thus leads astray no person of sound judgment, although he may be in error. the disposition of things in the present case are such, that, reasoning from his principles, this author could not see the truth; because he had not been persuaded, that aquiform strata could have been so changed by the chemical power of fusion, and the mechanical force of bending while in a certain state of softness. but though, in this case, the reasoning of this philosopher is to be justified, so far as he proceeded upon principles which could not lead him to the truth, his conduct is not so irreproachable in applying them to cases by which their fallacy might have been detected. this author acknowledges calcareous strata to be aquiform in their original; but, in those mountains which he has so much examined, he will find those aquiform bodies have undergone the same species of changes, which made him conclude that those schistus mountains had not been truly aquiform, as he at first had thought them. this would have led him to reason back upon his principles, and to say, _if one species of strata may be thus changed in its texture, and its shape, may not another be equally so? therefore, may not the origin of both be similar_? but least i should do injustice to this author, to whom we are indebted for many valuable observations in natural history, i shall transcribe what he has said upon the subject, being persuaded that my readers will not think this improper in me, or impertinent to the argument. "quand nous fumes une fois persuadés que la mer n'avoit pas fait toutes les _montagnes_, nous entreprîmes de découvrir les caractères distinctifs de celles qui lui devoient leur origine; et s'il étoit, par exemple, des matières qui leur fussent propres. mais nous y trouvâmes les mêmes difficultés qu'on rencontre dans tout ce qu'on veut classer dans la nature. on peut bien distinguer entr'elles les choses qui ont fortement l'empreinte de leur classe; mais les confins échappent toujours. "c'est là, pour le dire en passant, ce qui a pu conduire quelques philosophes à imaginer cette _chaîne des êtres_ où ils supposent, que, de la pierre à l'homme et plus haut, les nuances sont réellement imperceptibles. comme si, quoique les limites soyent cachées à nos sens, notre intelligence ne nous disoit pas, qu'il y a un _saut_, une distance même infinie, entre le plus petit degré d'organization _propageante_, et la matière unie par la simple cohésion: entre le plus petit degré de _sensibilité_, et la matière insensible: entre la plus petite capacité d'observer et de transmettre ses observations, et l'instinct constamment le même dans l'espèce. toutes ces différences tranchées existent dans la nature; mais notre incapacité de rien connoître à fond, et la necessité où nous sommes de juger de tout sur des apparences, nous fait perdre presque toutes les limites, parce que sur ces bords, la plupart des phénomènes sont équivoques. ainsi la plante nous paroît se rapprocher de la pierre, mais n'en approche jamais réellement. "on éprouve la même difficulté à classer les montagnes; et quoique depuis quelque tems plusieurs naturalistes ayent aussi observé qu'elles n'ont pas toutes la même origine, je ne vois pas qu'on soit parvenu à fixer des caractères infaillibles, pour les placer sûrement toutes dans leurs classes particulières. "après avoir examiné attentivement cet objet, d'après les phénomènes que j'ai moi-même observés, et ce que j'ai appris par les observations des autres; j'ai vu que c'étoit là un champ très vaste, quand on vouloit l'embrasser en entier, et trop vaste pour moi, qui n'étoit pas libre d'y consacrer tout le tems qu'il exige. je me suis donc replié sur mon objet principal, savoir _la cause qui a laissé des dépouilles marines dans nos continens_, et l'examen des hypothèses sur cette matière. "les phénomènes ainsi limités, se réduisent à ceci: qu'il y a dans nos continens des montagnes visiblement formées par des _dépôts successifs de la mer_ et a l'égard des quelles il n'y a besoin de rien imaginer, si ce n'est la manière dont elles en sont sorties: qu'il y en a d'autres au contraire, qui ne portent aucun des caractères de cette cause, et qui, si elles ont été produites dans la _mer_, doivent être l'effet de toute autre cause que de simples dépôts successifs, et avoir même précédé l'existence des animaux marins. j'abandonne donc les classes confuses où ces caractères sont équivoques, jusqu'à ce qu'elles servent à fonder quelque hypothèse; ayant assez de ces deux classes très distinctes pour examiner d'apres elles tous les systèmes qui me sont connus. "là où ces deux classes de montagnes sont mêlées, on remarque que celles qui sont formées par _couches_, et qui renferment des _corps marins_, recouvrent souvent celles de l'autre classe, mais n'en sont jamais recouvertes. on a donc naturellement conclu, que lors même que la _mer_ auroit en quelque part à la formation des montagnes où l'on ne reconnoît pas son caractère, celles auxquelles elle a travaillé seule, en enlevant des matières dans certaines parties de son fond et les déposant dans d'autres, font au moins les dernières formées. on les a donc nommées _secondaires_, et les autres _primitives_. "j'adopterai la première de ces expressions; car c'est la même qui nous étoit venu à l'esprit à mon frère, et à moi longtemps avant que nous l'eussions vue employer; mais je substituerai celle de _primordiales à_ _primitives_ pour l'autre classe de _montagnes_, afin de ne rien décider sur leur origine. il est des _montagnes_, dont jusqu'à present on n'a pu démêler la cause: voila le fait. je ne dirai donc pas qu'elles ont été créées ainsi, parce qu'en physique je ne dois pas employer des expressions sur lesquelles on ne s'entend pas. sans doute cependant, que l'histoire naturelle ni la physique ne nous conduisent nullement à croire que notre globe ait existé de toute éternité; et lorsqu'il prit naissance, il fallut bien que la matière qui le composa fut de quelque nature, ou sous quelque première forme intégrante. rien donc jusqu'ici n'empêche d'admettre que ces _montagnes_ que je nommerai _primordiales_, ne soient réellement _primitives_; je penche même pour cette opinion à l'égard de quelques unes. mais il y a une très grande variété entr'elles; et quoiqu'elles soyent toutes également exclues de la classe _secondaire_, elles ne sont pas toutes semblables: il y en a même un grand nombre dont les matières ont une certaine configuration qui semble annoncer qu'elles ayent été molles et durcies ensuite, quoique par une toute autre cause que celle qui a agi pour former les montagnes secondaires." here i would beg leave to call the attention of philosophers to this observation of a naturalist who explains all petrification, and the consolidation of strata by aqueous infiltration. if he has here found reason to conclude that, in those primordial parts of the earth, there are a great number which, from their present configuration, must have been in a soft state and then hardened, and this by a quite different cause from that which he supposes had produced the consolidation and hardness of the secondary parts; this is entering precisely into my views of the subject, in ascribing all the consolidation of the earth, whether primary or secondary, to one general cause, and in tracing this cause, from its effects, to be no other than the fusion of those bodies. it must be evident, that if this philosopher has seen good reason for concluding such a softening cause, which had operated upon the primary parts, to be quite different from that which he ascribes to the consolidation of the secondary, which is the effect of water, it must then, i say, be evident that the softening cause of the primary parts, if not heat, by which every degree of fusion may be produced, must be an occult cause, one which cannot be admitted into natural philosophy. by thus choosing to consider mountains as of two distinct kinds, one aquiform which is understood, and the other primordial which is not to be known, we supersede the necessity of reconciling a theory with many appearances in nature which otherwise might be extremely inconvenient to our explanation, if not inconsistent with our system. our author no doubt has thus relieved himself from a considerable difficulty in the philosophy of this earth, by saying here is a great part which is not to be explained. but i would beg leave to observe, that this form of discussion, with regard to a physical subject, is but a mere confession of our ignorance, and has no tendency to clear up another part of the subject of which one treats, however it may impress us with a favourable opinion of the theorist, in allowing him all the candour of the acknowledgement. the general result of the reasoning which we now have quoted, and what follows in his examination, seems to terminate in this; that there are various different compositions of mountains which this author cannot allow to be the production of the sea; but it is not upon account of the matter of which they are formed, or of the particular mixture and composition of those species of matter, of which the variety is almost indefinite. according to this philosopher, the distinction that we are to make of those primordial and secondary competitions, consists in this, that the first are in such a shape and structure as cannot be conceived to be formed by subsidence in water. m. de saussure has carefully examined those same objects; and he seems inclined to think that they must have been the operation of the ocean; not in the common manner of depositing strata, but in some other way by crystallization. the present theory supposes all those masses formed originally in the ordinary manner, by the deposits or subsidence of materials transported in the waters, and that those strata were afterwards changed by operations proper to the mineral regions. but the subject of the present investigation goes farther, by inquiring if, in the operations of the globe, a primary and secondary class of bodies may be distinguished, so far as the one may have undergone the operations of the globe, or the vicissitudes of sea and land, oftener than the other, consequently must be anterior to the later productions both in time and operation, although the original of all those bodies be the same, and the operations of the earth, so far as we see in the effects, always proceed upon the same principles. this is an extensive view of nature to which few have turned their thoughts. but this is a subject to which the observations described by this author have evidently a reference. in his th letter, he has given us a view of one of those parts of the earth that are proper to be examined in determining this question so important in the genealogy of land, although no ways concerned in altering the principles upon which nature in forming continents must proceed. it is in describing the nature of the mountains about _elbingerode_; and he begins in ascending from hefeld. "cette partie extérieure de la chaîne est _primordiale_: c'est du _granit_ à _hereld_ et au commencement de la route; puis quand on passe dans d'autres vallées, on trouve les _schistes_ et la _roche grise_ dans tout le pied des montagnes: mais des qu'on est arrivé à une certain hauteur, on voit de la _pierre à chaux_ par couches étendue sur ces matières; et c'est elle qui forme le sommet de ces mêmes montagnes; tellement que la plaine élevée, qui conduit à _elbingerode_, est entièrement de _pierre à chaux_, excepté dans sa partie la plus haute ou cette pierre est recouverte des mêmes _grès_ et sables _vitrescibles_ qui sont sur le schiste du bruchberg et sur la _pierre à chaux_ dans la _hesse_ et le pays de gottingue. "les environs d'elbingerode étant plus bas que ces parties recouvertes de matières vitrescibles, montrent la _pierre à chaux_ à nud; et l'on y trouve de très beaux marbres, dont les nuances jaunes, rouges et vertes sont souvent très vives, et embellies par les coupes des _corps marins_. "cependant le schiste n'est pas enseveli partout sous ces dépôts de la mer; on le retrouve en quelques endroits, et même avec de _filons_. "ainsi au milieu de ces matières _calcaires_ qui forment le sol montueux des environs _d'elbingerode_, paroît encore le _schiste_ sur lequel elles ont été déposées: et en montant à la partie la plus élevée de ces mêmes environs, on trouve que la _pierre à chaux_ est recouverte elle-même d'une _pierre sableuse_ grise par couches, dans laquelle on voit quantité de petits fragmens de _schiste_ posés de plat. c'est la que se trouve une des mines de _fer_ dont le minerai va en partie à la _koningshutte_, mais en plus grande partie à la _rothechutte_, qui n'est qu'à une lieue de distance. on perce d'abord la couche sableuse; sous elle se trouve de la _pierre à chaux_ grise; puis une couche de _pierre à chaux ferrugineuse_, remplie de _corps marins_, et surtout _d'entroques_: c'est cette _couche_ qui est ici le _minerai_; et elle appartient à la formation de cette éminence comme toutes les autres _couches_. cette mine se nomme _bomshey_: elle n'est pas riche; mais elle sert de _fondant_ aux matières ferrugineuses tirées des filons des montagnes primordiales en même tems qu'elle leur ajoute son _fer_ dans la fonte. a quelque distance de là on a percé un autre puits; qui a transversé d'abord une sorte de pierre, que je ne saurois nommer, mais qui ressemble fort à une _lave_ poreuse. au dessous de cette couche on a retrouvé la _pierre à chaux_ ordinaire; puis la _couche ferrugineuse_ y continue; mais elle diffère un peu de ce qu'elle est dans l'autre mine, une partie de sa substance étant convertie en _jaspe_. "mais ce qui est digne de la plus grande attention dans cette contrée, est un filon peu distant nomme _buchenberg_, qui appartient en partie au roi, et en partie à mr. le comte de _wernigerode_. la montagne en cette endroit montre une vallée artificielle de à pieds de profondeur, de à de largeur dans le haut, et de toises en étendue. c'est le creusement qu'on a déjà fait en suivant ce _filon_ de _fer_, que l'on continue à exploiter de la même manière sur les terres de mr. le comte de _wernigerode_. la matière propre de la montagne _est_ de _schiste_; et la vallée qui se forme de nouveau à mesure qu'on enlève la _gangue_ du _filon_, a sûrement déjà existé dans la mer sous la forme d'une _fente_, qui a été remplie, et en particulier des ingrédiens dont on fait aujourd'hui le _fer_." here is a supposition of our author that corresponds to nothing which has yet been observed any where else, so far as i know. it is concerning a mineral vein, one which does not appear to differ in any respect from other mineral veins, except in being worked in that open manner which has given our author an idea of its being a valley. he then supposes that valley (or rather empty vein) to have been in this mountain when at the bottom of the sea, and that this mineral vein had then been filled with those materials which now are found in that space between the two sides of the separated rock. this is a very different operation from that of infiltration, which is commonly supposed to be the method of filling mineral veins; but, we shall soon see the reason why our author has here deserted the common hypothesis, and has adopted another to serve the occasion, without appearing to have considered how perfectly inconsistent those two suppositions are to each other. that mineral veins have been filled with matter in a fluid state, is acknowledged by every body who has either looked at a mineral vein in the earth, or in a cabinet specimen; mineralists and geologists, in general, suppose this to have been done by means of solutions and concretions, a supposition by no means warranted by appearances, which, on the contrary, in general demonstrate that the materials of those veins had been introduced in the fluid state of fusion. but here is a new idea with regard to the filling of those veins; and, i would now beg the reader's attention to the facts which follow in this interesting description, and which have suggested that idea to our author. "quand cette matière accidentelle est enlevée, on voit la coupe du _schiste_ des deux côtes de la _fente_, faisant un _toit_ et un _mur_, parce que la _fente_ n'est pas absolument verticale: des qu'il y a un peu d'inclinaison, on distingue un _toit_ et un mur, comme j'ai l'honneur de l'expliquer à v.m. on ne connoît point encore l'étendue de ce filon, ni dans sa profondeur, où l'on ne peut pas s'enfoncer beaucoup de cette manière, ni dans la longueur, selon laquelle on continue à l'exploiter. "voilà donc un _filon_, à la rigueur de la définition que j'en ai donné à v.m. c'est à dire, une _fente_ dans la montagne naturelle, _comblée_ de _matière_ étrangère. mais ce qu'il y a d'extraordinaire ici, c'est que cette _matière_ vient de la _mer_: ce sont différentes _couches aquiformes_, dont quelques unes sont remplies de _corps marins_. il y a des _couches_ d'une _terre martiale_ fort brune et sans liaison: d'autres, au contraire toujours _martiales_, sont très dures et renferment de très beau jaspe sanguin: d'autres enfin sont de vrai _marbre_ gris veinées de rouge. c'est dans ce marbre que font les _corps marins_, savoir des coquillages et des spongites; et il est lui-même martial comme tout le reste: les mineurs le nomment _kubrimen_, et ne l'employent que comme un _fondant_ pour d'autres _minéraux de fer_. "a ce _filon_, s'en joignent d'autres plus embarrassans. ils viennent du _toit_, qu'ils divisent par de larges _fentes_ comblées, aboutissantes au _filon_ principale. ils font de même _calcaires_ et marins faits par _couches_; mais ces _couches_ ont une si grande inclinaison, que je ne puis les comprendre: il faut qu'il y ait eu d'étranges bouleversemens dans ces endroits-là[ ]. [note : here, no doubt, are appearances which it is impossible to explain by the theory of infiltration; it is the filling of mineral veins, and their branches or ramifications, with marble containing marks of marine objects. but, if we shall suppose this marble to have been in the fluid state of fusion, as well as the iron-ore and jasper, we may easily conceive it introduced into the principal vein and its branches. the description here given of those appearances is by no means such as to enable us to judge particularly of this case, which surely merits the most accurate investigation, and which, i doubt not, will give physical demonstration of the fusion of those mineral substances. i know that shells have been found within the body of veins in germany; but, a stratification of those materials in a vein was never heard of before, so far as i know.] "ces _fentes_ se sont faites, et ont été remplies, dans la _mer_; puisque les matières qui les remplissent sont de la classe de ses dépôts très connoissables, et qu'il contiennent des _dépouilles marines_. mais ce qui embarrasse alors c'est que les autres _filons_ ne soyent pas dans le même cas. n'est ce point là encore un indice, que ces _fentes_ out été d'abord et principalement remplies de matières, poussées du fond par la même force qui secouoit les montagnes[ ]. [note : but what is this power by which matter is to be forced from the bottom of the sea to the top of the mountains? for, unless we can form some idea of that power which, as a cause, we ascribe to the perceived effect, we either say nothing to the purpose, or we employ a preternatural cause. it is not sufficient to imagine a power capable of raising from the bottom of the sea the materials deposited in the abyss; it is also necessary to find a power capable of softening bodies which are hard, and of thus consolidating those masses which are formed of loose or unconnected materials. such a power, indeed, the present theory assumes; and, so far as this shall be implied in the supposition of our author, it will thus have received a certain conformation.] "ce _filon_ n'est pas le seul dans le _hartz_ qui donne des signes _marins_. il y en a un autre, qui même se rapproche davantage de la nature du commun des _filons_, et où l'on trouve aussi des _coquillages_. c'est celui de _haus-hartzbergerzug_, pres de _clausthal_, où, dans les _halles_ de quelques mines de plomb abandonnées, et dans une forte _d'ardoise_, on trouve de petites _moules_ ou _tellines_ striées, d'une espèce particulière que j'ai vue dans des _ardoises secondaires d'arotzen_ en _waldek_ et de _sombernon_ en _bourgogne_. il y a donc certainement quelques _filons_ faits par les dépôts de la _mer_ dans les _fentes_ de montagnes _primordiales_; comme au contraire il y a des _filons_ métalliques sans indices _marins_, dans des montagnes évidemment _secondaires_, telles que celles de _derbyshire_, ou les _filons_ de _plomb_ traversent des couches de _pierre à chaux_." here again our author seems to me to refute his own supposition, that a chasm in the schistus rock may have existed at the bottom of the sea, and been then filled from above with such materials as were transported by the moving water to that place, is not impossible; but nobody, who knows the nature of a common metallic vein, can ever suppose it to have been filled in that manner. our author then adds, "on ne fait réellement que commencer dans ce genre d'observations, considérées quant à la cosmologie; ainsi il ne faut point désespérer que tout cela ne se dévoile un jour, et que nous n'acquerrions ainsi un peu plus de connoissance sur ce qui se passoit dans la _mer ancienne_. "en revenant vers _elbingerode_, nous retrouvâmes ces _schistes_, qui paroissent au travers des _marbres:_ ils sont donc la continuation de la masse _schisteuse_ à laquelle appartient le _filon_, dont je viens de parler. ce _filon_ à été formé dans une _fente_, restée ouverte et vide: les dépôts de la _mer_ l'ont comblée, en même tems qu'ils formoient les couches de _marbre_, qui sont à l'extérieur. en effet, ce _filon_ contient des _couches marines ferrugineuses_, de la même nature que celles des collines calcaires voisines formées sur le schiste. "nous partîmes _d'elbingerode_ dans l'après midi pour nous rapprocher de clausthal. notre chemin fut encore quelque tems sur des sommités _calcaires_; et avant que d'en sortir, nous trouvâmes une autre mine singulière à _arenfeld_. c'est encore un vrai _filon_; mais dans une montagne de _pierre à chaux:_ c'est à-dire, que cette montagne a aussi été _fendue_, et que la _fente_ a été remplie d'une _gangue_. la matière de ce _filon_ est encore _calcaire_ en plus grande partie; mais cette _pierre à chaux_ distincte est _ferrugineuse_, et parsemée de concrétions de _jaspe_ comme celles _d'elbingerode:_ on y trouve aussi une matière verdâtre, qui, comme le _jaspe_, ne fait pas effervescence avec l'eau forte." here is a phenomenon which is altogether incompatible with the theory that this author has given us for the explanation of those appearances. he supposes empty crevices in the schistus mountains at the bottom of the sea; these crevices he supposes filled by the deposits of the sea, at the same time, and with the same materials with which the lime-stone strata were formed above the schistus mountains; but we find one of those same veins in these secondary calcareous strata. now, tho' we should be disposed to allow, that, in the primordial mountain, of which we are supposed not to know the origin, there might have been empty crevices which were afterwards filled with materials transported by the sea, this cannot be admitted as taking place in the loose or incoherent materials deposited above the schistus. consequently, this theory of our author, which is evidently erroneous with regard to the veins in the lime-stone, must, in the other case, be at least examined with a jealous eye. "le haut de cette partie des montagnes _calcaires_ étoit encore recouvert de _sable_ et de grès _vitrescibles_: et continuant à marcher, sans aucune inflexion sensible, nous nous trouvâmes subitement sur les _schistes_; d'où nous montâmes plus rapidement. puis traversant quelques petites vallées nous arrivâmes sur les montagnes qui appartiennent au prolongement du _brocken_ ou _blocksberg_. la matière dominante est alors le _granit_; mais il est tout en blocs le long de cette route, et ces blocs se trouvent à une telle distance de tout sommité intacte de cette pierre, qui est aisé de juger non seulement qu'ils ne sont pas dans leur place originaire, mais encore qu'il ne sont arrivés là par aucune des causes naturelles qui agissent dans les montagnes; savoir, la pesanteur, la pente, et le cours des eaux. ce sont donc de violentes explosions qui ont dispersé ces blocs; et alors ils deviennent un nouveau trait cosmologique de quelque importance: car rien ne se meut, ni ne paroît s'être mu depuis bien des siècles, dans ces lieux qui montrent tant de désordre: un tapis de verdure couvre tout, en conservant les contours baroques du sol. le bétail ne sauroit pâturer dans de telles prairies; mais l'industrieux montagnard fait y faucher[ ]. [note : m. de saussure endeavours to explain those appearances of transported blocks of granite by another cause; this is a certain _debacle_ of the waters of the earth, which i do not understand. m. de luc again attempts to explain it by violent explosions; i suppose he means those of a volcano. but he has not given us the evidence upon which such an opinion may be founded, farther than by saying that those blocks could not have come there by the natural operations of the surface. by this must be meant, that, from the nearest summit of granite, there is not, at present, any natural means by which these blocks might be transported to that place. but it is not with the present state of things that we are concerned, in explaining the operations of a distant period. if the natural operations of the surface change the shape of things, as is clearly proved by every natural appearance, why form an argument against a former transaction, upon the circumstances of the present state of things? our author does not seem to perceive, that, from this mode of reasoning, there is is an insuperable objection to his violent explosions having been employed in producing those effects. for, had there been such a cause, the evidence of this must have remained; if the surface of the earth does not undergo great changes: if, again, this surface be in time much changed, how can we judge from the present shape, what might have been the former posture of things? this author, indeed, does not allow much time for the natural operations of the globe to change its surface; but, if things be not greatly removed from the state in which the violent operations of the globe had placed them, why does he not point out to us the source of this great disorder which he there perceives? from what explosion will be explained the blocks of granite which are found upon the jura, and which must have come from the mass of _mont blanc_? if these dispersed blocks of stone are to be explained by explosion, there must: have been similar explosions in other countries where there is not the smallest appearance of volcanic eruptions; for, around all our granite mountains, and i believe all others, there are found many blocks of granite, traveled at a great distance, and in all directions.] "_oberbruck_, ou nous avions été la précédente fois, se trouva sur notre route, et nous y passames aussi la nuit, dans l'espérance de pouvoir monter le lendemain sur le _brocken_; mais il fut encore enveloppé de nuages; ainsi nous continuâmes à marcher vers _clausthal_, passant de nouveau par le _bruchberg_, où le _sable_ et ses gres recouvrent le _schiste_; puis arrivant à une autre sommité, nous y trouvâmes la même pierre _sableuse_ par couches, mêlée de parcelles de _schiste_, que nous avions vue sur les montagnes _calcaires d'elbingerode_. il est donc toujours plus certain que le sol primordial de toutes ces montagnes existoit sous les eaux de l'ancienne mer; puisqu'il est recouvert de diverses fortes de dépôts, connus pour appartenir à la _mer_; et que les _fentes_ des _filons_ existoient dans cette _mer ancienne_; puisqu'elle en a rempli elle-même quelques unes, et qu'elle a recouvert de ses dépôts quelques autres _filons_ tout formés. quant à celles des matières de ces _filons_, qui ne paroissent pas être _marines_ (et c'est de beaucoup la plus grande quantité), j'ai toujours plus de penchant d'en attribuer une partie à l'opération des _feux souterreins_, à mesure que je vois diminuer la probabilité de les assigner entièrement à _l'eau_. mais quoi-qu'il en soit, ces gangues ne font pas de même date que les montagnes[ ]. [note : i most willingly admit the justness of our author's view, if he thus perceives the operation of fire in the solids of our earth; but it is not for the reasons he has given us for discovering it here more than in other places; for there is not a mineral vein, (so far at least as i have seen), in which the appearances may be explained by any thing else besides the operation of fire or fusion. it is not easy to conceive in what manner our author had conceived the opinions which he has displayed in these letters. he had no opinion of this kind, or rather he was persuaded that subterraneous fire had no hand in the formation of this earth before he came to this place of the hartz; here he finds certain appearances, by which he is confirmed in his former opinion, that water had operated in forming mineral veins; and then he forms the idea that subterraneous fire may have operated also. but, before the discovery of the chasms in the schistus mountains having been filled with the stratified materials of the sea, how had he supposed veins to be filled? if this philosopher had before no opinion of subterraneous fire, as instrumental in that operation, how comes he now to change that former opinion? for, unless it be the extraordinary manner of filling these open crevices in the mountains by matter deposited immediately from the sea, there is certainly no other appearance in this mineral country of the hartz, that may not be found in any other, only perhaps upon a smaller scale.] "le lendemain de notre arrivée a _clausthal_, qui étoit le e, nous allâmes visiter d'autres mines de _fer_ en montagnes secondaires, situées au côté opposé du hartz. elles sont auprès de _grund_ l'une des _villes de mines_, et près du lieu ou sortira la nouvelle _galerie d'écoulement_ à laquelle on travaille, etc. "arrivés à _grund_ les officiers mineurs vinrent, comme à l'ordinaire, accompagner mons. de _reden_ aux _mines_ de leur département. celles-ci, sans être plus extraordinaires que celles qui nous avions vues à _elbingerod_, ou sans aider mieux jusqu'ici à expliquer ce qu'elles ont toutes d'extraordinaire, nous donnent au moins des indices probables de grands accidens. ces montagnes de _grund_ sont encore de l'espèce remarquable, dont la base est de _schiste_, et le haut de _pierre à chaux_. les mines qu'on y exploit sont de _fer_, et se trouvent dans cette matière _calcaire_; mais elles y sont sous des apparences tout-à-fait étranges. la montagne où nous les vîmes principalement le nomme _iberg_. on y poursuit des masses de _pierre à fer_, de l'ensemble desquelles les mineurs ne peuvent encore se rendre compte d'une manière claire. ils ont trouvé dans cette montagne des _ca__vernes_, qui ressemblent à l'encaissement de _sillons_ déjà exploités, ou non formés; c'est-à-dire, que ce sont des _fentes_ presque verticales, et vides, le _minerai_ qu'ils poursuivent est en _rognons_; c'est à dire, en grandes masses sans continuité décidée. cependant ces masses semblent se succéder dans la montagne suivant une certaine direction; tellement que les mineurs savent déjà les chercher, par des indices d'habitude. la substance de cette _pierre à fer_ particulière renferme des crystallizations de diverses espèces. il y a des _druses de quartz_, ou de petits cristaux de quartz qui tapissent des cavités; il y a aussi du _spath_ commun, et de celui qu'on nomme pesant; on y trouve enfin une forte de crystallization nommée _eisenman_ (_homme de fer_) par les mineurs; se sont des amas de cristaux noir-âtres, qui ressemblent à des groupes de grandes lentilles plattes, et ces cristaux sont _ferrugineux_. "entre les signes de bouleversement que renferme ce lieu, est un rocher nommé _gebichensten_, qui est en _pierre à chaux_, ce que _l'ebrenbreitstein_ de _coblentz_ est en pierre sableuse: c'est-à-dire, que ses _couches_, remplies de _corps marins_, sont presque verticales; ceux de ces corps qu'on y trouve en plus grande quantité, sont des _madrépores_. ce rocher s'élève comme un grand obélisque, au-dessus des _cavernes_, dont j'ai parlé; montrant par le côté ses _couches_, qui se trouvent, comme je l'ai dit, dans une situation presque verticale. sa base est déjà bien minée, tant par les _cavernes_, que par la _pierre à fer_ qu'on en tire; et je ne me hasardai dessus, que parce que je me dis, qu'il y a des millions contre un à parier, que ce n'est pas le moment où il s'enfoncerait. mais je n'en dirois pas autant, s'il s'agissoit de m'y loger à demeure. "quoique tout ce lieu là soit fort remarquable, il se pourrait que ce ne fut qu'un phénomène particulier. les _cavernes_ peuvent devoir leur origine à la même cause que celle de schartzfeld; et le dérangement des rochers supérieurs à des enfoncemens occasionnés par ces _cavernes_. rien n'est si difficile que de retracer aujourd'hui ces fortes d'accidens à cause des changemens que le tems y a opérés. s'ils sont arrivés sous les eaux de la _mer_, on conçoit aisément les altérations qui ont dû succéder; et si c'est depuis que nos continens sont à sec, les eaux encore, tant intérieures qu'extérieures, et la végétation, en ont beaucoup changé l'aspect." this author has a theory by which he explains to himself the former residence of the sea, above the summits of our mountains; this, however, is not the theory by which we are now endeavouring to explain appearances; we must therefore be allowed to reason from our own principles, in considering the facts here set forth by our author. nothing, i think, is more evident, than that in this mineral country of the hartz, we may find the clearest marks of fracture, elevation, and dislocation of the strata, and of the introduction of foreign matter among those separated bodies. all those appearances, our author would have to be nothing but some particular accident, which is not to enter into the physiology of the earth. i wish again to generalise these facts, by finding them universal in relation to the globe, and necessarily to be found in all the consolidated parts of our land. it was not to refute our author's reasoning that i have here introduced so much of his observations, but to give an extensive view of the mineral structure of this interesting country. this therefore being done, we now proceed to what is more peculiarly our business in this place, or the immediate subject of investigation, viz. the distinction of primary and secondary strata. "dans le voisinage de cette montagne, il y a une autre fort intéressante, que je vis le jour suivant. quoiqu'en traitant des volcans, j'aie démontré que la formation des montagnes, par soulèvement, étoit sans exemple dans les faits, et sans fondement dans la théorie, je ne laisseroi pas de m'arrêter au phénomène que présente cette montagne; parce qu'il prouvera directement que les _couches calcaires_ au moins, ont été formées _à la hauteur ou elles sont_; c'est-a-dire qu'elles n'ont pas été soulevées. "voulant prendre l'occasion de mon retour à _hanovre_, pour traverser les avant-corps du _hartz_, dans quelque nouvelle direction; je résolus de faire ce voyage à cheval, et de prendre ma route droite vers _hanovre_, au-travers des collines; ce qui me conduisit encore à _grund_ puis à _münchehof brunshausen, engelade, winsenburg_ et _alfeld_, où enfin, traversant la _leine_ j'entrai dans la grande route. "je quittai donc _clausthal_ (et avec bien du regret) le au matin; et revenant d'abord à _grund_, je le laissai sur ma droite, ainsi que _l'iberg_; et plus loin, du même côté, une autre montagne nommée _winterberg_ dont la base est _schiste_, et le sommet plus haut que clausthal, entièrement composé de _couches calcaires_. de _grund_ je montai vers une montagne nommée _ost kamp_; et je commençai là à donner une attention particulière au sol. le long de mon chemin, je ne trouvai longtemps que des schistes, qui montroient leurs points en haut, comme à l'ordinaire, et avec tous leurs tortillemens de feuillets. mais arrivé au haut de la montagne, j'y vis des carrières de _pierre à chaux_, où les couches absolument régulières, et qui ont peu d'épaisseur sur le _schiste_ suivent parfaitement les contours du _sommet_. ces lits de _pierre à chaux_ n'ont certainement pas été soulevés du fond de la _mer_ sur le dos des schistes; lors même qu'à cause de la grande inclinaison des feuillets de ceux-ci on voudroit le attribuer à quelque révolution telle que le _soulèvement_; (ce que je n'admettrois point). car si ces lits _calcaires_, ayant été faits au fond de la _mer_, avoyent été soulevés avec les schistes, ne feroient-ils pas brisés et bouleversés comme eux? il est donc evident, que quoiqu'il soi arrivé au schiste qui les porte, ces lits, et tous les autres de même genre qui sont au haut de ces montagnes, ont été déposées au niveau où ils sont; et que par conséquent la _mer_ les surpassoit alors. ainsi le système de soulèvement perd son but, s'il tend à expliquer pourquoi nous avons des _couches_, formées par la mer, qui se trouvent maintenant si fort au dessus de son niveau. il est évident que ces _couches_ n'ont pas été soulevées; mais que la _mer_ s'est _abaissée_. or c'est là le grand point cosmologique à expliquer: tous les autres, qui tiennent à la structure de certaines montagnes inintelligibles, n'appartiendront qu'à _l'histoire naturelle_, tant qu'ils ne se lieront pas avec celui-la." here are two things to be considered; the interesting facts described by our author, and the inference that he would have us draw from those facts. it would appear from the facts, that the body of schistus below, and that of lime-stone above, had not undergone the same disordering operations, or by no means in the same degree. but our author has formed another conclusion; he says, that these lime-stone strata must have been formed precisely in the place and order in which they lie at present; and the reason for this is, because these strata appeared to him to follow perfectly the contour of the summit of this mountain. now, had there been in the top of this mountain a deep hollow encompassed about with the schistus rock; and had this cavity been now found filled with horizontal strata, there might have been some shadow of reason for supposing those strata to have been deposited upon the top of the mountain. but to suppose, _first_, that shells and corals should be deposited upon the convex summit of a mountain which was then covered by the sea; _secondly_, that these moveable materials should remain upon the summit, while the sea had changed its place; and, _lastly_, that those shells and corals left by the sea upon the top of a mountain should become strata of solid limestone, and have also metallic veins in it, certainly holds of no principle of natural philosophy that i am acquainted with. if, therefore, such an appearance as this were to be employed either in illustration or confirmation of a theory, it would itself require to be explained; but this is a task that this cosmologists does not seem willing to undertake. he has formed a hypothesis for explaining the general appearance of that which was once the bottom of the sea being now found forming the summits of our mountains; but surely this philosopher will acknowledge, that those natural appearances, in any particular place, will be the same, whether we suppose the bottom of the sea to have been raised, as in the present theory, or the surface of the sea to have sunk according to his hypothesis. for, it is equally easy to suppose a portion of the earth to have been raised all this height, as to suppose all the rest of the surface of the globe to have sunk an equal space, while a small portion of the bottom of the sea, remaining here and there fixed in its place, became the highest portion of the globe. consequently, whatever evidence this philosopher shall find in support of his theory of the present earth, (a subject which it is not our purpose to examine) it cannot be allowed that he has here brought any argument capable of disproving the elevation of the bottom of the sea; a supposition which other theories may require. i would now observe, in relation to the present theory, that so far as this author has reasoned justly from natural appearances, his conclusions will be found to confirm the present supposition, that there is to be perceived the distinction of primordial, and that of secondary, in the masses of this earth, without altering the general theory either with respect to the original formation of those masses, or to their posterior production. here one of two things must be allowed; either that those strata of schistus had been broken and distorted under a mass of other superincumbent strata; or that those superincumbent strata had been deposited upon the broken and distorted strata at the bottom of the sea. our author, who has examined the subject, inclines to think, that this last has been the case. if, therefore, strata had been deposited upon broken and bare rocks of schistus, it is probable that these had been sunk in the sea after having been exposed to the atmosphere, and served the purpose of land upon the globe.[ ] [note : this is also supported by another very interesting observation contained in this letter. m. de luc observes, that in this country the schistus is generally covered by strata of lime-stone, and that these lime-stone strata are again covered with those of sand-stone, in which are found a great many fragments of schistus lying flat. therefore, while those sand-stone strata were collecting at the bottom of the sea, there had been rocks of schistus in some other place, from whence those fragments bad been detached.] an example of the same kind also occurs in the _discours sur l'histoire naturelle de la suisse_; and this author of the _tableaux de la suisse_ has given a very distinct description of that appearance, which is perhaps the more to be valued as a piece of natural history, as this intelligent author does not pretend to any geological theory, but simply narrates what he has seen, with such pertinent observations on the subject as naturally must occur to a thinking person on the spot.--(discours, etc. page . entrée au pays de grisons). "du village d'elen on continue à monter le reste du petit vallon pendant une lieue et demie parmi les mêmes espèces de pierres qu'on vient de décrire; en passant au travers de bois et de forêts de sapins et de quelques pâturages dont ce haut est couvert, on parvient au pied du bundnerberg, montagne des grisons, qui forme la tête du vallon. on laisse à droite un fond ou espèce d'entonnoir, entouré de très-hautes montagnes inaccessibles, pour s'enfourrer à gauche entre des rochers qui font fort resserrés, où coule un torrent. ce lieu seroit horreur si on ne se trouvoit accoutumé, par degrés, à voir de ces positions effrayantes: tout y est aride, il n'y a plus d'arbres ni de végétaux ce sont des rochers entassés les un sur les autres; ce lieu paroit d'autant plus affreux que le passage a été subit, et qu'en sortant de bois et des forêts, on se trouve tout-à-coup parmi ces rochers qui s'élèvent comme des murailles, et dont on ne voit pas la cime; cette gorge ou cette entrée qui se nomme jetz, est la communication du canton du glaris aux gritons; on a dit précédemment qu'il y en avoit une plus aisée par le gros-thal ou le grand vallon. ce passage est très-curieux pour la lithogeognosie, il est rare de trouver autant de phénomènes intéressans rassemblés, et des substances aussi variées par rapport à leurs positions; c'est le local qui mérite le plus d'être examiné en suisse, et la plus difficile que nous ayons parcouru. on se souviendra que nous avons continuellement monté depuis glaris, et que nous nous trouvons au pied de ces montagnes ou de ces pics étonnans qui dominent les hautes alpes; on trouve ici la facilité peu commune de pouvoir examiner, et voir le pied ou les fondemens de ces colosses qui couronnent le globe, parce qu'ils sont ordinairement entourés de leurs débris et de leurs éboulemens qui en cachent le pied. ici c'est une roche de schiste bleuâtre, dure et compact, traversée de filons de quartz blanc, et quelquefois jaunâtre, dans laquelle on a taillé un sentier pour pouvoir en franchir le pied. cette roche s'élève à une hauteur prodigieuse, est presque verticale, et ces couches sont à quatre-vingt degrés d'inclinaison. l'imagination est effrayée de voir que de pareilles masses ayent pu être ébranlées et déplacées au point d'avoir fait presque un quart de conversion. après avoir monté et suivi cette roche parmi les pierres et les décombres, une heure et demie, on trouve cette roche de schiste surmontée d'autres rochers fort hauts qui sont calcaires, et dont les lits sont fort horizontaux. les schistes, qui sont directement sous les roches calcaires, conservent la même inclinaison qu'elles ont à leur pied." here is an observation which certainly agrees with that given by m. de luc, and would seem to confirm this conclusion, that strata had been deposited upon those _schisti_ after they had been changed from their natural or horizontal position, and become vertical; at the same time, this conclusion is not of necessary consequence, without examining concomitant appearances, and finding particular marks by which this operation might be traced; for the simply finding horizontal strata, placed above vertical or much inclined schiste, is not sufficient, of itself, to constitute that fact, while it is acknowledged that every species of fracture, dislocation, and contortion, is to be found among the displaced strata of the globe. since writing this chapter, i am enabled to speak more decisively upon that point, having acquired more light upon the subject, as will appear in the next chapter. chap. vi. the theory of interchanging sea and land illustrated by an investigation of the primary and secondary strata. sect. i.--a distinct view of the primary and secondary strata. having given a view of what seems to be the primary and secondary strata, from the observations of authors, and having given what was my opinion when i first wrote that chapter, i am now to treat of this subject from observations of my own, which i made since forming that opinion. from portpatrick, on the west coast, to st abb's head, on the east, there is a tract of schistus mountains, in which the strata are generally much inclined, or approaching to the vertical situation; and it is in these inclined strata that geologists allege that there is not to be found any vestige of organised body. this opinion, however, i have now proved to be erroneous. there cannot be any doubt with regard to the original formation of those stratified bodies, as having been formed of the materials that are natural to this earth, viz. the detritus of former bodies; and as having been deposited in water, like the horizontal strata: for the substances and bodies of which they are visibly composed are no other than those which form the most regular horizontal strata, and which are continually traveling, or transported at the bottom of the sea, such as gravel, and sand, argillaceous and micaceous bodies. on each side of this ridge of mountains, which towards the east end is but narrow, there is a lower country composed of strata in general more horizontal; and among which strata, besides coal, there are also found the relics of organised bodies. abstracting at present from any consideration of organised bodies among the materials of those strata, it may be affirmed, that the materials which form the strata in the mountains and in the low country, are similar, or of the same nature; that they have, in both places, been consolidated by the same means, viz. heat and fusion; and that the same or similar accidents have happened to them, such as change from their original position, and mineral veins traversing them in various shapes. yet still there is a distinctive character for those two bodies, the alpine and the horizontal strata; for, while the horizontal position appears natural to the one, and the changes from that particular state to be only an accident, the vertical position appears to be more natural to the other, which is seldom found horizontal. therefore, altho' it is unquestionable that the strata in the alpine and low countries had the same or a similar original, yet, as the vertical position, which is the greatest possible change in that respect, is more natural to the alpine strata, or only necessary in the natural order of those bodies, we are to consider this great disorder or change from the natural state of their original formation, as the proper character of those alpine strata. but then it is also necessary to include in this character a general hardness and solidity in those vertical strata, otherwise they would not have been properly alpine, or have resisted the wearing and washing powers of the globe, so as to have remained higher than the others; for, the vertical position, or great inclination of those strata, should rather have disposed them the more to dissolution and decay. let us now see how far we shall be justified in that general conclusion, by the examination of those bodies. the fact is certain, that those alpine bodies are much harder, or less subject to dissolution and decay, than the horizontal strata. but this must be taken in the general, and will by no means apply to particular cases which might be compared. nothing, for example, more solid than the lime-stones, or marbles, and iron-stones; nothing more hard or solid than the chirt or flint; and all these are found among the horizontal strata. but, while some strata among those horizontal beds are thus perfectly solid, others are found with so slight degrees of consolidation, that we should not be able to ascribe it to the proper cause, without that gradation of the effect, which leads us to impute the slightest degree of consolidation to the same operations that have produced the complete solidity. while, therefore, the most perfect solidity is found in certain strata, or occasionally among the horizontal bodies, this forms no part of their character in general, or cannot be considered as a distinctive mark, as it truly is with regard to the alpine strata. these last have a general character of consolidation and indissolubility, which is in a manner universal. we are, therefore, now to inquire into the cause of this distinction, and to form some hypothesis that may be tried by the actual state of things, in being compared with natural appearances. as the general cause of consolidation among mineral bodies, formed originally of loose materials, has been found to consist in certain degrees of fusion or cementation of those materials by means of heat; and as, in the examination of the horizontal strata we actually find very different degrees of consolidation in the several strata, independent of their positions in relation to height or depth, we have reason to believe that the heat, or consolidating operation, has not been equally employed in relation to them all. we are not now inquiring how an inferior stratum should have been heated in a lesser degree, or not consolidated, while a superior stratum had been consolidated in the most perfect manner; we are to reason upon a fact, which is, that the horizontal strata in general appear not to have been equally or universally consolidated; and this we must attribute to an insufficient exertion of the consolidating cause. but, so far as the erecting cause is considered as the same with that by which the elevated bodies were consolidated, and so far as the vertical situation is a proof of the great exertion of that subterraneous power, the strata which are most erected, should in general be found most consolidated. nothing more certain than that there have been several repeated operations of the mineralising power exerted upon the strata in particular places; and all those mineral operations tend to consolidation: therefore, the more the operations have been repeated in any place, the more we should find the strata consolidated, or changed from their natural state. vertical strata have every appearance from whence we should be led to conclude, that much of the mineral power had been exerted upon them, in changing their original constitution or appearance. but the question now to be considered is this, how far it may appear that these masses of matter, which now seem to be so different from the ordinary strata of the globe, had been twice subjected to the mineral operations, in having been first consolidated and erected into the place of land, and afterwards sunk below the bottom of the sea, in order a second time to undergo the process of subterraneous heat, and again be elevated into the place where they now are found. it must be evident, here is a question that may not be easy to decide. it is not to the degree of any change to which bodies may be subject, that we are to appeal, in order to clear up the point in question, but to a regular course of operations, which must appear to have been successively transacted, and by which the different circumstances or situations of those masses are to be discovered in their present state. now, though it does not concern the present theory that this question be decided, as it is nothing but a repetition of the same operations that we look for; nevertheless, it would be an interesting fact in the natural history of this earth; and it would add great lustre to a theory by which so great, so many operations were to be explained. i am far from being sanguine in my expectations of giving all the satisfaction in relation to this subject that i could wish; but it will be proper to state what i have lately learned with regard to so curious a question, that others, who shall have the opportunity, may be led to inquire, and that thus the natural history of the earth may be enlarged, by a proper investigation of its mineral operations. with this view i have often considered our schistus mountains, both in the north and south; but i never found any satisfactory appearance from whence conclusions could be formed, whether for the question or against it. the places i examined were those between the alpine countries and the horizontal strata; here, indeed, i have frequently found a confused mass, formed of the fragments of those alpine strata mixed with the materials of the horizontal bodies; but not having seen the proper shape and connection of those several deposits, i always suspended my judgment with regard to the particular operations which might have been employed in producing those appearances. i had long looked for the immediate junction of the secondary or low country strata with the alpine schistus, without finding it; the first place in which i observed it was at the north end of the island of arran, at the mouth of loch ranza; it was upon the shore, where the inclined strata appeared bare, being; washed by the sea. it was but a very small part that i could see; but what appeared was most distinct. here the schistus and the sandstone strata both rise inclined at an angle of about °; but these primary and secondary strata were inclined in almost opposite directions; and thus they met together like the two sides of a _lambda_, or the rigging of a house, being a little in disorder at the angle of their junction. from this situation of those two different masses of strata, it is evidently impossible that either of them could have been formed originally in that position; therefore, i could not here learn in what state the schistus strata had been in when those of the sand-stone, &c, had been superinduced. such was the state of my mind, in relation to that subject:, when at jedburgh upon a visit to a friend, after i had returned from arran, and wrote the history of that journey; i there considered myself as among the horizontal strata which had first appeared after passing the tweed, and before arriving at the tiviot. the strata there, as in berwickshire, which is their continuation to the east, are remarkably horizontal for scotland; and they consist of alternated beds of sand-stone and marl, or argillaceous and micaceous strata. these horizontal strata are traversed in places with small veins of whin-stone, as well as greater masses forming rocks and hills of that material; but, except it be these, (of which there are some curious examples), i thought there could be nothing more of an interesting nature to observe. chance, however, discovered to me what i could not have expected or foreseen. the river tweed, below melrose, discovers in its bed the vertical strata of the schistus mountains, and though here these indurated bodies are not veined with quartz as in many places of the mountains, i did not hesitate to consider them as the same species, that is to say, the marly materials indurated and consolidated in those operations by which they had been so much changed in their place and natural position. afterwards in travelling south, and seeing the horizontal softer strata, i concluded that i had got out of the alpine country, and supposed that no more of the vertical strata were to be observed. the river tiviot has made a wide valley as might have been expected, in running over thole horizontal strata of marly or decaying substances; and the banks of this river declining gradually are covered with gravel and soil, and show little of the solid strata of the country. this, however, is not the case with the jed, which is to the southward of the tiviot; that river, in many places, runs upon the horizontal strata, and undermines steep banks, which falling shows high and beautiful sections of the regular horizontal strata. the little rivulets also which fall into the jed have hollowed out deep gullies in the land, and show the uniformity of the horizontal strata. in this manner i was disposed to look for nothing more than what i had seen among those mineral bodies, when one day, walking in the beautiful valley above the town of jedburgh, i was surprised with the appearance of vertical strata in the bed of the river, where i was certain that the banks were composed of horizontal strata. i was soon satisfied with regard to this phenomenon, and rejoiced at my good fortune in stumbling upon an object so interesting to the natural history of the earth, and which i had been long looking for in vain. here the vertical strata, similar to those that are in the bed of the tweed, appear; and above those vertical strata, are placed the horizontal beds, which extend along the whole country. the question which we would wish to have solved is this; if the vertical strata had been broken and erected under the superincumbent horizontal strata; or if, after the vertical strata had been broken and erected, the horizontal strata had been deposited upon the vertical strata, then forming the bottom of the sea. that strata, which are regular and horizontal in one place, should be found bended, broken, or disordered at another, is not uncommon; it is always found more or less in all our horizontal strata. now, to what length this disordering operation might have been carried, among strata under others, without disturbing the order and continuity of those above, may perhaps be difficult to determine; but here, in this present case, is the greatest disturbance of the under strata, and a very great regularity among those above. here at least is the most difficult case of this kind to conceive, if we are to suppose that the upper strata had been deposited before those below had been broken and erected. let us now suppose that the under strata had been disordered at the bottom of the sea, before the superincumbent bodies were deposited; it is not to be well conceived, that the vertical strata should in that case appear to be cut off abruptly, and present their regular edges immediately under the uniformly deposited substances above. but, in the case now under consideration, there appears the most uniform section of the vertical strata, their ends go up regularly to the horizontal deposited bodies. now, in whatever state the vertical strata had been in at the time of this event, we can hardly suppose that they could have been so perfectly cut off, without any relict being left to trace that operation. it is much more probable to suppose, that the sea had washed away the relics of the broken and disordered strata, before those that are now superincumbent had been begun to be deposited. but we cannot suppose two such contrary operations in the same place, as that of carrying away the relics of those broken strata, and the depositing of sand and subtile earth in such a regular order. we are therefore led to conclude, that the bottom of the sea, or surface of those erected strata, had been in very different situations at those two periods, when the relics of the disordered strata had been carried away, and when the new materials had been deposited. if this shall be admitted as a just view of the subject, it will be fair to suppose, that the disordered strata had been raised more or less above the surface of the ocean; that, by the effects of either rivers, winds, or tides, the surface of the vertical strata had been washed bare; and that this surface had been afterwards sunk below the influence of those destructive operations, and thus placed in a situation proper for the opposite effect, the accumulation of matter prepared and put in motion by the destroying causes. i will not pretend to say that this has all the evidence that should be required, in order to constitute a physical truth, or principle from whence we were to reason farther in our theory; but, as a simple fact, there is more probability for the thing having happened in that manner than in any other; and perhaps this is all that may be attained, though not all that were to be wished on the occasion. let us now see how far any confirmation may be obtained from the examination of all the attending circumstances in those operations. i have already mentioned, that i had long observed great masses of _debris_, or an extremely coarse species of pudding-stone, situated on the south as well as north sides of those schistus mountains, where the alpine strata terminate in our view, and where i had been looking for the connection of those with the softer strata of the low country. it has surely been such appearances as these which have often led naturalists to see the formation of secondary and tertiary strata formed by the simple congestion of _debris_ from the mountains, and to suppose those masses consolidated by the operation of that very element by which they had been torn off from one place and deposited in another. i never before had data from whence to reason with regard to the natural history of those masses of gravel and sand which always appeared to me in an irregular shape, and not attended with such circumstances as might give light into their natural history; but now i have found what i think sufficient to explain those obscure appearances, and which at the same time will in some respect illustrate or confirm the conjecture which has now been formed with regard to the operations of the globe in those regions. in describing the vertical and horizontal strata of the jed, no mention has been made of a certain pudding-stone, which is interposed between the two, lying immediately upon the one and under the other. this puddingstone corresponds entirely to that which i had found along the skirt of the schistus mountains upon the south side, in different places, almost from one end to the other. it is a confused mass of stones, gravel, and sand, with red marly earth; these are consolidated or cemented in a considerable degree, and thus form a stratum extremely unlike any thing which is to be found either above or below. when we examine the stones and gravel of which it is composed, these appear to have belonged to the vertical strata or schistus mountains. they are in general the hard and solid parts of those indurated strata, worn and rounded by attrition; particularly sand or marl-stone consolidated and veined with quartz, and many fragments of quartz, all rounded by attrition. in this pudding-stone of the jed, i find also rounded lumps of porphyry, but have not perceived any of granite.[ ] this however is not the case in the pudding-stone of the schistus mountains, for, where there is granite in the neighbourhood, there is also granite in the pudding-stone. [note : a view of this object is seen in plate d. it is from a drawing taken by mr clerk of eldin.] from this it will appear, that the schistus mountains or the vertical strata of indurated bodies had been formed, and had been wasted and worn in the natural operations of the globe, before the horizontal strata were begun to be deposited in those places; the gravel formed of those indurated broken bodies worn round by attrition evince that fact. but it also appears that the mineral operations of the globe, melting and consolidating bodies, had been exerted upon those deposited strata above the vertical bodies. this appears evidently from the examination of our pudding-stone. the vertical strata under it are much broken and injected with ferruginous spar; and this same spar has greatly penetrated the pudding-stone above, in which are found the various mineral appearances of that spar and iron ore. but those injecting operations reach no farther up among the marl strata in this place; and then would appear to have been confined to the pudding-stone. but in another place, about half a mile farther up the river, where a very deep section of the strata is discovered, there are two injections from below; the one is a thin vein of whin-stone or basaltes, full of round particles of steatites impregnated with copper; it is but a few inches wide, and proceeds in a kind of zigzag. the other appears to have been calcareous spar, but the greatest part of it is now dissolved out. the strata here descend to the bottom of the river, which is above the place of the pudding-stone and vertical strata. neither are these last discoverable below the town of jedburgh, at least so far as i have seen; and the line of division, or plane of junction of the vertical and horizontal strata, appears to decline more than the bed of the river. but it may be asked, how the horizontal strata above, among which are many very strong beds, have been consolidated. the answer to this question is plain. those strata have been indurated or consolidated in no other manner than the general strata of the earth; these being actually the common strata of the globe; while the vertical or schistus strata are the ordinary strata still farther manufactured, (if we may be allowed the expression) in the vicissitude of things, and by the mineral operations of the globe. that those operations have been performed by subterraneous heat has been already proved; but i would now mention some particular appearances which are common or general to those strata, and which can only be explained upon that principle. the red marly earth is prevalent among those strata; and it is with this red ferruginous substance that many of the sand-stone strata are tinged. it is plain that there had been an uniform, deposits of that sand and tinging earth; and that, however different matter might be successively deposited, yet that each individual stratum should be nearly of the same colour or appearance, so far as it had been formed uniformly of the same subsiding matter. but, in the most uniform strata of red sand-stone, the fracture of the stone presents us with circular spots of a white or bluish colour; those little spheres are in all respects the same with the rest of the stone, they only want the tinging matter; and now it may be inquired how this has come about. to say that sphericles of white sand should have been formed by subsiding along with the red sand and earth which composed the uniform stratum whether of sand-stone or marl, (for it happens equally in both,) is plainly impossible, according to our notion of that operation in which there is nothing mysterious. those foliated strata, which are of the most uniform nature, must have been gradually accumulated from the subsiding sand and earth; and the white or colourless places must have had their colour destroyed in the subsequent cementing operations. it is often apparent, that the discharging operation had proceeded from a centre, as some small matter may be perceived in that place. i know not what species of substance this has been, whether saline or phlogistic, but it must have had the power of either volatilising or changing the ferruginous or red tinging substance so as to make it lose its colour. i have only mentioned spherical spots for distinctness sake; but this discharging operation is found diversifying those strata in various ways, but always referable to the same or similar causes. thus, in many of the veins or natural cracks of those strata, we find the colour discharged for a certain space within the strata; and we often see several of those spots united, each of them having proceeded from its own centre, and uniting where they approached. in the two veins above mentioned, of whin-stone and spar traversing the strata, the colour of the strata is, discharged more or less in the places contiguous with the veins. i am now to mention another appearance of a different kind. those strata of marl are in general not much consolidated; but among, them there are sometimes found thin calcareous strata extremely consolidated, consequently much divided by veins. it is in the solid parts of those strata, perfectly disconnected from the veins, that there are frequent cavities curiously lined with crystals of different sorts, generally calcareous, sometimes containing also those that are siliceous, and often accompanied with pyrites. i am persuaded that the origin of those cavities may have been some hollow shells, such as _echini_ or some marine object; but that calcareous body has been so changed, that it is not now distinguishable; therefore, at present, i hold this opinion only as conjecture. having, in my return to edinburgh, traveled up the tiviot, with a view to investigate this subject of primary and secondary operations of the earth, i found the vertical strata, or alpine schistus, in the bed of the river about two miles below hawick. this was the third time i had seen those vertical bodies after leaving the mountains of lauderdale. the first place was the bed of the river tweed, at the new bridge below melrose; but here no other covering is to be seen above those vertical strata besides the soil or traveled earth which conceals every thing except the rock in the bed of the river. the second place was jedburgh, where i found the vertical strata covered with the horizontal sandstone and marl, as has been now described. the third place was the tiviot, and this is that which now remains to be considered. seeing the vertical strata in the bed of the river, i was desirous to know if those were immediately covered with the horizontal strata. this could not be discovered in the bed of the river where the rock was covered upon the banks with travelled earth. i therefore left the river, and followed the course of a brook which comes from the south side. i had not gone far up the bank, or former boundary of the tiviot, when i had the satisfaction to find the vertical strata covered with the pudding-stone and marly beds as in the valley of the jed. it will now be reasonable to suppose that all the schistus which we perceive, whether in the mountains or in the valleys, exposed to our view had been once covered with those horizontal strata which are observed in berwickshire and tiviotdale; and that, below all those horizontal strata in the level country, there is at present a body or basis of vertical or inclined schistus, on which the horizontal strata of a secondary order had been deposited. this is the conclusion that i had formed at jedburgh, before i had seen the confirmation of it in the tiviot; it is the only one that can be formed according to this view of things; and it must remain in the present state until more evidence be found by which the probability may be either increased or diminished. since writing this, i have read, in the esprit de journaux, an abstract of a memoir of m. voigt, upon the same subject, which i shall now transcribe. "la mer a commencé par miner les montagnes primitives dont les débris se sont précipités au fond. ces débris forment la premiere couche qui est posée immédiatement sur les montagnes primitives. d'après l'ancien langage de mineurs, nous avons jusqu'aujourd'hui appellé cette couche _le sol mort rouge_, parce qu'il y a beaucoup de rouge dans son mélange, qu'elle forme le sol ou la base d'autres couches, et peut-être de toutes, qu'elle est entierement inutile et, en quelque facon, morte pour l'exploitation des mines. plusieurs se sont efforcés de lui donner un nom harmonieux; mais ils ne l'ont pu sans occasionner des équivoques. les mots _brèche puddinstone conglomérations_, &_c_. désignent toujours des substances autres que cette espèce de pierre. "il est très agréable de l'examiner dans les endroits où elle forme des montagnes entières. cette couche est composée d'une quantité prodigieuse de pierres arrondies, agglutinées ensemble par une substance argileuse rouge et même grise, et le toute a acquis assez de dureté. on ne trouve dans sa composition aucune espèce de pierre qui, à en juger par les meilleures observations, puisse avoir été formée plus tard qu'elle; on n'y voit par-tout que des parties et des produit des montagnes primitives principalement de celles qui abondent le plus dans ces contrées. le sol mort, par exemple, qui compose les montagnes des environs de walbourg, près d'eisenach, contient une quantité de gros morceaux de granit et de schiste micacé; c'est vraisemblablement parce que les montagnes primitives les plus voisines de rhula, etc. sont, pour la plus part, formées de ces deux espèces de pierres. près de goldlauter, le sol mort consiste presque tout en porphyre, substance dont sont formées les montagnes primitives qui y dominent; et le kiffauserberg dans la thuringe a probablement reçu ces morceaux arrondis de schiste argileux des montagnes voisine du hartz. vous trouverez ici que le schiste argileux existoit déjà lorsque la mer a jetté les premiers fondemens de nos montagnes stratifiées. je serois fort étonné que quelqu'un me montrât un sol mort qui contînt un morceaux de gypse, de marne, de pierre puante et autres. quoiqu'il en soit il n'est pas aisé d'expliquer pourquoi on ne trouve point de corps marins pétrifiés dans cette espèce de pierre. c'est peut-être que, par l'immense quantité de pierres dures roulées dans le fond de la mer, ils ont été brisés avant qu'ils aient commencé de s'agglutiner ensemble. mais on rencontre sur-tout au kiffhauserberg des troncs d'arbres entiers pétrifiés; preuve qu'il y avoit déjà ou de la végétation avant que l'océan destructeur se fût emparé de ces cantons, ou du moins que quelques isles avoient existé au-dessus de la surface." here we find the same observations in the mountains of germany that i have been making with regard to those of scotland. i have formerly observed masses of the same kind in the west of england, to the east of the severn; but i could not discover any proper connection of that mass with the regular strata. i have also long observed it in many parts of scotland, without being able to attain a sufficiently satisfactory idea with regard to those particulars by which the alternation of land and water, of the superficial and internal mineral operations of the globe, might be investigated. it will be very remarkable if similar appearances are always found upon the junction of the alpine with the level countries. such an appearance, i am inclined to think, may be found in the val d'aoste, near yvrée. m. de saussure describes such a stone as having been employed in building the triumphal arch erected in honour of augustus. "cet arc qui étoit anciennement revêtu de marbre, est construit de grands quartiers d'une espèce assez singulière de poudingue ou de grès à gros grains. c'est une assemblage de fragmens, presque touts angulaires, de toutes sortes de roches primitives feuilletées, quartzeuses, micacées; les plus gros de ces fragmens n'atteignent pas le volume, d'une noisette. la plupart des édifices antiques de la cité l'aoste et de ses environs, sont construits de cette matière; et les gens du pays sont persuadés que c'est une composition; mais j'en ai trouvé des rochers en place dans les montagnes au nord et au-dessus de la route d'yvrée." we may now come to this general conclusion, that, in this example of horizontal and posterior strata placed upon the vertical _schisti_ which are prior in relation to the former, we obtain a further view into the natural history of this earth, more than what appears in the simple succession of one stratum above another. we know, in general, that all the solid parts of this earth, which come to our view, have either been formed originally by subsidence at the bottom of the sea, or been transfused in a melted state from the mineral regions among those solid bodies; but here we further learn, that the indurated and erected strata, after being broken and washed by the moving waters, had again been sunk below the sea, and had served as a bottom or basis on which to form a new structure of strata; and also, that those new or posterior strata had been indurated or cemented by the consolidating operations of the mineral region, and elevated from the bottom of the sea into the place of land, or considerably above the general surface of the waters. it is thus that we may investigate particular operations in the general progress of nature, which has for object to renovate the surface of the earth necessarily wasted in the operation of a world sustaining plants and animals. it is necessary to compare together every thing of this kind which occurs; it is first necessary to ascertain the fact of their being a prior and posterior formation of strata, with the mineral operations for consolidating those bodies formed by collection of the moveable materials; and, secondly, it is interesting to acquire all the data we can in order to form a distinct judgment of that progress of nature in which the solid body of our land is alternately removed from the bottom of the sea into the atmosphere, and sunk again at the bottom of the sea. i shall now transcribe what m. schreiber has wrote in relation to this subject. it is in a memoir concerning the gold mine of gardette, published in the journal de physique. "avant de quitter la montagne de la gardette qu'il me soit permis de rapporter une observation qui peut-être n'est pas dénuée de tout intérêt pour les naturalistes; je l'ai faite dans une galerie à environ cinquante-trois toises à l'ouest du principal puit laquelle a été poussée sur la ligne de réunion de la pierre calcaire, et du granit feuilleté ou gneiss pour fonder le filon dans cet endroit. ce filon a six pouces d'épaisseur, et consiste en quartz entre-mêlé d'ochre martiale, de pyrite cuivreuse et galène. cette dernière est souvent recouverte de chaux de plomb grise, et de petits cristaux de mine de plomb jaune donnant dans l'analyse un indice d'or. ce filon finit à la réunion de la pierre calcaire au gneiss. cette réunion se fait ici dans la direction d'une heure / de la boussole de raineur, et sous un inclinaison, occidentale de degrés. "mais ce qu'il y a de remarquable, c'est que le gneis ne participe en rien de la pierre calcaire quoiqu'il n'en soit séparé que par une couche d'une pouce d'épaisseur de terre argileuse et calcaire, tandis que le rocher calcaire renferme beaucoup de fragmens de granit et de gneis, dans le voisinage de cette réunion. "cette observation prouve incontestablement que le granit et le gneis avoient déjà acquis une dureté capable de résister aux infiltration des parties calcaire, et qu'ils existoient à-peu-près tels qu'ils sont aujourd'hui lorsque la pierre calcaire commença à se former; autrement elle n'auroit pu saisir et envelopper des morceaux détachés de ces rochers auxquels on donne avec raison l'épithète de primitif ou de première formation." m. schreiber continues his reasoning upon those mineral appearances, in adducing another argument, which i do not think equally conclusive. he says, "le filon de la gardette devoit pareillement exister avant la montagne calcaire, car s'il s'étoit formé apres, je ne voit pas la raison pour laquelle il s'y seroit arrêté court, et pourquoi il ne se seroit pas prolongé dans cette espèce de rocher." it is not necessary, in the formation of a vein, that it should proceed in traversing all the strata which then are superincumbent; it is reasonable to suppose, and consistent with observation to find them stop short in proceeding from one stratum to another. had m. schreiber found any pieces of the vein contained in the calcareous rock, he would have had good reason for that assertion; but, to conclude that fact from grounds which do not necessarily imply it, is not to be permitted in sound reasoning, if certainty is the object, and not mere probability. sect. ii.--the theory confirmed from observations made on purpose to elucidate the subject. having got a distinct view of the primary and secondary mineral bodies or strata of the globe, and having thus acquired a particular object to inquire after, with a view to investigate or illustrate this piece of natural history, i was considering where we might most probably succeed in finding the junction of the low country strata and alpine schistus. i inquired of mr hall of whitehall, who had frequent opportunities of traversing those mountains which lie between his house in the merse and edinburgh; and i particularly entreated him to examine the bed of the whittater, which he executed to my satisfaction. mr hall having had occasion to examine the pease and tour burns, in planning and superintending the great improvement of the post road upon sir james hall's estate while sir james was abroad, he informed me that the junction of the schistus and sand-stone strata was to be found in the tour burn. professor playfair and i had been intending a visit to sir james hall at dunglass; and this was a motive, not so much to hasten our visit, as to chose the most proper time for a mineral expedition both upon the hills and along the sea shore. it was late in the spring when sir james left town, and mr playfair and i went to dunglass about the beginning of june. we had exceeding favourable weather during the most part of our expedition; and i now propose to give an account of the result of our observations. dunglass burn is the boundary between the counties of east lothian and berwickshire; and it is almost the boundary between the vertical and horizontal strata. to the north-west of this burn and beautiful dean are situated the coal, lime-stone, marl, and sand-stone strata; they are found stretching away along the shore in a very horizontal direction for some time, but become more and more inclined as they approach the schistus of which the hills of lammermuir to the south are composed. though the boundary between the two things here in question be easily perceivable from the nature of the country at the first inspection, by the rising of the hills, yet this does not lead one precisely to the junction; and in the extensive common boundary of those two things, the junction itself is only to be perceived in few places, where the rock is washed bare by the rivers or the sea, and where this junction is exposed naked to our view. the sea is here wearing away the coast; and the bank, about feet high, is gradually falling down, making in some places a steep declivity, in others a perpendicular cliff. st abb's head and fast castle are head lands projecting into the sea, and are the bulwarks of this shore, which is embayed to the westward, where the sea preys upon the horizontal strata. the solid strata are every where exposed either in the cliff or on the shore; we were therefore certain of meeting with the junction in going from dunglass to fast castle, which is upon the schistus. but this journey can only be made by sea; and we first set out to examine the junction in the tour and pease burns, where we had been informed it was to be found. in the bottom of those rivulets the sand-stone and marly strata appear pretty much inclined, rising towards the schistus country. the two burns unite before they come to the shore; and it is about midway between this junction and the bridges which are thrown over those two hollows, that the junction is to be found. the schistus strata here approach towards vertical; and the sand-stone strata are greatly inclined. but this inclination of those two different strata are in opposite directions; neither does the horizontal section of those two different strata run parallel to the junction; that is to say, the intersection of those two different strata is a line inclined to the horizon. at jedburgh the schistus was vertical, and the strata horizontal; and there was interposed a compound bed of pudding-stone, formed of various water-worn bodies, the gravel of the schistus strata, and porphyries. here again, though we have not a regular pudding-stone, we have that which corresponds to it, as having been the effect of similar circumstances. these are the fracture and detritus of the schistus, while the strata were deposited upon the broken ends of the schistus at the bottom of the sea. most of the fragments of the schistus have their angles sharp; consequently, they had not travelled far, or been much worn by attrition. but more or less does not alter the nature of an operation; and the pudding-stone, which at jedburgh is interposed between the vertical schistus and horizontal strata, is here properly represented by the included fragments of schistus in the inclined strata. the line of this junction running, on the one hand, towards fast castle eastward, and, on the other, towards the head of dunglass burn westward, our business was to pursue this object in those two different directions. but it was chiefly in the sea coast that was placed our expectations, having recollection of the great banks of gravel under which the strata are buried about oldhamstocks, near which, from all appearances, the junction was to be expected. having taken boat at dunglass burn, we set out to explore the coast; and, we observed the horizontal sand-stone turn up near the pease burn, lifting towards the schistus. we found the junction of that schistus with the red sand-stone and marly strata on the shore and sea bank, at st. helens, corresponding in general with what we had observed in the burns to the westward. but, at siccar point, we found a beautiful picture of this junction washed bare by the sea. the sand-stone strata are partly washed away, and partly remaining upon the ends of the vertical schistus; and, in many places, points of the schistus strata are seen standing up through among the sand-stone, the greatest part of which is worn away. behind this again we have a natural section of those sand-stone strata, containing fragments of the schistus. after this nothing appears but the schistus rocks, until sand-stone and marl again are found at red-heugh above the vertical strata. from that bay to fast castle we had nothing to observe but the schistus, which is continued without interruption to st abb's head. beyond this, indeed, there appears to be something above the schistus; and great blocks of a red whin-stone or basaltes come down from the height and lie upon the shore; but we could not perceive distinctly how the upper mass is connected with the vertical schistus which is continued below. our attention was now directed to what we could observe with respect to the schisti, of which we had most beautiful views and most perfect sections. here are two objects to be held in view, in making those observations; the original formation or stratification of the schisti, and the posterior operations by which the present state of things has been procured. we had remarkable examples for the illustration of both those subjects. with regard to the first, we have every where among the rocks many surfaces of the erected strata laid bare, in being separated. here we found the most distinct marks of strata of sand modified by moving water. it is no other than that which we every day observe upon the sands of our own shore, when the sea has ebbed and left them in a waved figure, which cannot be mistaken. such figures as these are extremely common in our sand-stone strata; but this is an object which i never had distinctly observed in the alpine schisti; although, considering that the original of those schisti was strata of sand, and formed in water, there was no reason to doubt of such a thing being found. but here the examples are so many and so distinct, that it could not fail to give us great satisfaction. we were no less gratified in our views with respect to the other object, the mineral operations by which soft strata, regularly formed in horizontal planes at the bottom of the sea, had been hardened and displaced. fig. . represents one of those examples; it was drawn by sir james hall from a perfect section in the perpendicular cliff at lumesden burn. here is not only a fine example of the bendings of the strata, but also of a horizontal shift or hitch of those erected strata. st abb's head is a promontory which, at a distance, one would naturally conclude to be composed of the schisti, as is all the shore to that place; but, as we approached it, there was some difference to be perceived in the external appearance, it having a more rounded and irregular aspect. accordingly, upon our arrival, we found this head-land composed of a different substance. it is a great mass of red whin-stone, of a very irregular structure and composition. some of it is full of small pebbles of calcareous spar, surrounded with a coat of a coloured substance, different both from the whin-stone ground and the inclosed pebble. here ended our expedition by water. having thus found the junction of the sand-stone with the schistus or alpine strata to run in a line directed from fast castle to oldhamstocks, or the heads of dunglass burn, we set out to trace this burn, not only with a view to observe the junction, if it should there appear, but particularly to discover the source of many blocks of whin-stone, of all sizes, with which the bed of this burn abounds. the sand-stone and coal strata, which are nearly horizontal at the mouth of this burn, or on the coast, become inclined as we go up the course of the rivulet; and of this we have fine sections in the bank. the dean of dunglass is formed of precipitous and perpendicular rocks, through which the running water has worn its way more than a hundred feet deep; above this dean the banks are steep and very high, but covered with soil, which here is a deep gravel. the burn runs all the way up to oldhamstocks upon the sand-stone strata; but there, these are traversed by a high whin-stone dyke, which crosses the burn obliquely, as we found it on both banks though not in the bed of the burn; it is in the south bank below the village, and on the north above it. here is the source of the whin-stone which we were looking for; it is the common blue basaltes, of the same nature with the giant's causeway, but with no regular columner appearance. above oldhamstocks we again found the sand-stone in the bank, but it soon disappeared under a deep cover of gravel, and the burn then divided into several rivulets which come from the hills. we traced the one which led most directly up to the mountains, in expectation of meeting with the schistus, at least, if not the junction of it with the sandstone. but in this we were disappointed. we did not however lose our labour; for, though the junction which we pursued be not here visible, we met with what made it sufficiently evident, and was at the same time an object far more interesting in our eyes. i have already quoted mr voigt's description of the _sol mort rouge_; he says, that in places it forms entire mountains; here we have a perfect example of the same thing; and the moment we saw it, we said, here is the _sol mort rouge_. we ascended to the top of the mountain through a gully of solid pudding-stone going into decay, and furnishing the country below with that great covering of gravel, soil, and water worn stones. we were now well acquainted with the pudding-stone, which is interposed between the horizontal and alpine strata; but from what we had seen to the eastward, we never should have dreamed of meeting with what we now perceived. what we had hitherto seen of this pudding-stone was but a few fragments of the schistus in the lower beds of sand-stone; here a mountain of water-worn schisti, imbedded in a red earth and consolidated, presented itself to our view. it was evident that the schisti mountains, from whence those fragments had come, had been prior to this secondary mass; but here is a secondary mountain equal in height to the primary, or schisti mountains, at the basis of which we had seen the strata superinduced on the shore. still, however, every thing here is formed upon the same principle, and nothing here is altered except the scale on which the operation had been performed. upon the coast, we have but a specimen of the pudding-stone; most of the fragments had their angles entire; and few of them are rounded by attrition. here, on the contrary, the mountain is one pudding-stone; and most of the fragments are stones much rounded by attrition. but the difference is only in degree, and not in kind; the stones are the same, and the nature of the composition similar. had we seen the mass of which this mountain is only a relict, (having been degraded by the hands of time), we should have found this pudding-stone at the bottom of our sand-stone strata; could we have penetrated below this mass of pudding-stone, we should have found our schistus which we left on the shore at st. helens and in the tour burn. in tiviotdale the vertical schisti are covered with a bed of pudding-stone, the gravel of which had been much worn by attrition, but the thickness of that bed is small; here again the wearing operation has been great, and the quantity of those materials even more than in proportion to those operations. we returned perfectly satisfied; and sir james hall is to pursue this subject farther when he shall be in those mountains shooting muir game. we had now only one object more to pursue; this was to examine the south side of those mountains of lammermuir upon the sea shore, in order to see the junction of the primary schistus with the coal strata of berwickshire. mr hall was to meet us at the press, and we were afterwards to go with him to whitehall. we met accordingly; but the weather was rainy; and we went directly to whitehall. i had often seen the pudding-stone in great masse; in the banks of the whiteader, as it comes out of the mountains, but then i had not seen its connection neither, on the one hand, with the schisti, nor, on the other, with the sand-stone strata. we knew that at lammerton upon the sea coast there was coal, and consequently the sand-stone strata; and reasoning upon those data we were sure that our proper course of investigation was to trace the river ey to the shore, and then go south the coast in search of the junction of the schistus with the horizontal strata. this we executed as well as the weather would permit; but had it to regret, that the rainy season was not so favourable for our views, as it was agreeable to the country which had been suffering with the drought. it is needless now to enlarge upon this subject. i shall only mention that we found the red marly strata above the pudding-stone in the bed of the ey and its branches; we then traced the schistus down the ey, and found a mass of the most consolidated pudding-stone upon the coast to the north of the harbour of eymouth. but this mass did not rest on the schistus; it is immediately upon a mass of whin-stone; and the schistus is in the harbour, so that this whin-stone mass seems to be here interposed between the pudding-stone and schistus. we then pursued the coast southwards until we found the junction of the schistus and sand-stone strata about two miles from eymouth; but here the junction was not attended with any pudding-stone that we could perceive. having found the same or similar appearances from the one end to the other, and on both sides of that range of mountains which run from sea to sea in the south of scotland, we may now extend our view of this mineral operation in comprehending every thing of the same kind which we meet with in our island or any other distant country. thus perhaps the pudding-stone of the south of england will be considered in the same light as having been formed of the _débri_ and _détritus_ of the flinty bodies. in the island of arran, there is also a pudding-stone, even in some of the summits of the island, exactly upon the border of the schistus district, as will be described in the natural history of that island. this pudding-stone is composed of gravel formed of the hardest parts of the schistus and granite or porphyry mountains. that compound parasitical stone has been also again cemented by heat and fusion; i have a specimen in which there is a clear demonstration of that fact. one of the water-worn stones which had been rounded by attrition, has in this pudding-stone been broken and shifted, the one half slipping over the other, three quarters of an inch, besides other smaller slips in the same stone. but the two pieces are again cemented; or they had been shifted when the stone was in that soft state, by which the two pieces are made perfectly to cohere. those shifts and veins, in this species of stone, are extremely instructive, illustrating the mineral operations of the globe. in like manner to the north of the grampians, along the south side of loch ness, there are mountains formed of the debris of schistus and granite mountains, first manufactured into sand and gravel, and then consolidated into a pudding-stone, which is always formed upon the same principle. the same is also found upon the south side of those mountains in the shire of angus. i may also give for example the african _brechia_, which is a pudding-stone of the same nature. this stone is composed of granites or porphyries, serpentines and schisti, extremely indurated and perfectly consolidated. it is also demonstrable from the appearance in this stone that it has been in a softened state, from the shape and application of its constituent parts; and in a specimen of it which i have in my cabinet, there is also a demonstration of calcareous spar flowing among the gravel of the consolidated rock. this fact therefore of pudding-stone mountains, is a general fact, so far as it is founded upon observations that are made in africa, germany, and britain. we may now reason upon this general fact, in order to see how far it countenances the idea of primitive mountains, on the one hand, or on the other supports the present theory, which admits of nothing primitive in the visible or examinable parts of the earth. to a person who examines accurately the composition of our mountains, which occupy the south of scotland, no argument needs be used to persuade him that the bodies in question are not primitive; the thing is evident from inspection, as much as would be the ruins of an ancient city, although there were no record of its history. the visible materials, which compose for the most part the strata of our south alpine schisti, are so distinctly the _debris_ and _detritus_ of a former earth, and so similar in their nature with those which for the most part compose the strata on all hands acknowledged as secondary, that there can remain no question upon that head. the consolidation, again, of those strata, and the erection of them from their original position, and from the place in which they had been formed, is another question. but the acknowledging strata, which had been formed in the sea of loose materials, to be consolidated and raised into the place of land, is plainly giving up the idea of primitive mountains. the only question, therefore, which remains to be solved, must respect the order of things, in comparing the alpine schisti with the secondary strata; and this indeed forms a curious subject of investigation. it is plain that the schisti had been indurated, elevated, broken, and worn by attrition in water, before the secondary strata, which form the most fertile parts of our earth, had existed. it is also certain that the tops of our schistus mountains had been in the bottom of the sea at the time when our secondary strata had begun to be formed; for the pudding-stone on the top of our lammermuir mountains, as well as the secondary strata upon the vertical schisti of the alps and german mountains, affords the most irrefragable evidence of that fact. it is further to be affirmed, that this whole mass of water-formed materials, as well as the basis on which it rested, had been subjected to the mineral operations of the globe, operations by which the loose and incoherent materials are consolidated, and that which was the bottom of the sea made to occupy the station of land, and serve the purpose for which it is destined in the world. this also will appear evident, when it is considered that it has been from the appearances in this very land, independent of those of the alpine schisti, that the present theory has been established. by thus admitting a primary and secondary in the formation of our land, the present theory will be confirmed in all its parts. for, nothing but those vicissitudes, in which the old is worn and destroyed, and new land formed to supply its place, can explain that order which is to be perceived in all the works of nature; or give us any satisfactory idea with regard to that apparent disorder and confusion, which would disgrace an agent possessed of wisdom and working with design. chap. vii. opinions examined with regard to petrifaction, or mineral concretion. the ideas of naturalists with regard to petrifaction are so vague and indistinct, that no proper answer can be given to them. they in general suppose water to be the solvent of bodies, and the vehicle of petrifying substances; but they neither say whether water be an universal menstruum, nor do they show in what manner a solid body has been formed in the bowels of the earth, from that solution. it may now be proper to examine this subject, not with a view to explain all those petrifactions of bodies which is performed in the mineral regions of the earth, those regions that are inaccessible to man, but to show that what has been wrote by naturalists, upon this subject, has only a tendency to corrupt science, by admitting the grossest supposition in place of just principle or truth, and to darken natural history by introducing an ill conceived theory in place of matter of fact. m. le comte de buffon has attempted to explain the crystallization of bodies, or production of mineral forms, by the accretion or juxtaposition of elementary bodies, which have only form in two dimensions, length and breadth; that is to say, that mineral concretions are composed of surfaces alone, and not of bodies. this however is only an attempt to explain, what we do not understand, by a proposition which is either evidently contradictory, or plainly inconceivable. it is true that this eloquent and ingenious author endeavours to correct the palpable absurdity of the proposition, by representing the constituent parts of the mineral bodies as "_de lames infiniment minces_;" but who is it does not see, that these infinitely thin plates are no other than bodies of three dimensions, contrary to the supposition; for, infinitely thin, means a certain thickness; but the smallest possible or assignable thickness differs as much from a perfect superficies as the greatest. m. de luc has given us his ideas of petrifaction with sufficient precision of term and clearness of expression; his opinion, therefore, deserves to be examined; and, as his theory of petrifaction is equally applicable to every species of substance, it is necessary again to examine this subject, notwithstanding of what has been already said, in the first part of this work, concerning consolidation and mineral concretion from the fluid state of fusion. this author has perhaps properly exposed woodward's theory of petrification in saying[ ], "son erreur à cet égard vient de ce qu'il n'a point réfléchi sur la manière dont se fait la _pétrifaction_. il ramollit d'abord les _pierres_ pour y faire entrer les coquilles, sans bien connoître l'agent qu'il y employe; et il les duroit ensuite, sans réfléchir au comment." to avoid this error or defect, m. de luc, in his theory of petrifaction, sets out with the acknowledged principle of cohesion; and, in order to consolidate strata of a porous texture, he supposes water carrying minute bodies of all shapes and sizes, and depositing them in such close contact as to produce solidity and concretion. now, if dr woodward softened stones without a proper cause, m. de luc, in employing the specious principle of cohesion, has consolidated them upon no better grounds; for, the application of this principle is as foreign to his purpose, as is that of magnetism. bodies, it is true, cohere when their surfaces are closely applied to each other; but how apply this principle to consolidation?--only by supposing all the separate bodies, of which the solid is to be composed, to be in perfect contact in all their surfaces. but this, in other words, is supposing the body to be solid; and, to suppose the agent, water, capable of thus making hard bodies solid, is no other than having recourse to the fortuitous concourse of atoms to make a world; a thought which this author would surely hold in great contempt. [note : lettres physiques et morales.] he then illustrates this operation of nature by those of art, in building walls which certainly become hard, and which, as our author seems to think, become solid. but this is only an imperfect or erroneous representation of this subject; for, mortar does not become hard upon the principle of petrification adopted by our author. mortar, made of clay, instead of lime, will not acquire a stony hardness, nor ever, by means of water, will it be more indurated than by simply drying; neither will the most subtile powder of chalk, with water and sand, form any solid body, or a proper mortar. the induration of mortar arises from the solution of a stony substance, and the subsequent concretion of that dissolved matter, operations purely chemical. now, if this philosopher, in his theory of petrifaction, means only to explain a chemical operation upon mechanical principles, why have recourse, for an example in this subject, to mineral bodies, the origin of which is questioned? why does he not rather explain, upon this principle, the known concretion of some body, from a fluid state, or, conversely, the known solution of some concreted body? if again he means to explain petrifaction in the usual way, by a chemical operation, in that case, the application of his polished surfaces, so as to cohere, cannot take place until the dissolved body be separated from the fluid, by means of which it is transported from place to place in the mineral regions. but it is in this preliminary step that lies all the difficulty; for, could we see how every different substance might be dissolved, and every dissolved substance separated from its solvent at our pleasure, we should find no difficulty in admitting the cohesion of hard bodies, whether by means of this doctrine of polished surfaces, or by the principle of general attraction, a principle which surely comprehends this particular, termed a cohesive power. it must not be alleged, that seeing we know not how water dissolves saline bodies, therefore, this fluid, for any thing that we know, may also dissolve crystal; and, if water thus dissolves a mineral substance in a manner unknown to us, it may in like manner deposit it, although we may not be able to imagine how. this kind of reasoning is only calculated to keep us in ignorance; at the same time, the reasoning of philosophers, concerning petrifaction, does not in general appear to be founded on any principle that is more sound. that water dissolves salt is a fact. that water dissolves crystal is not a fact; therefore, those two propositions, with regard to the power of water, are infinitely removed, and cannot be assimilated in sound physical reasoning. it is no more a truth that water is able to dissolve salt, than that we never have been able to detect the smallest disposition in water to dissolve crystal, flint, quartz, or metals. therefore, to allege the possibility of water being capable of dissolving those bodies in the mineral regions, and of thus changing the substance of one body into another, as naturalists have supposed, contrary to their knowledge, or in order to explain appearances, is so far from tending to increase our science, that it is abandoning the human intellect to be bewildered in an error; it is the vain attempt of lulling to sleep the scientific conscience, and making the soul of man insensible to the natural distress of conscious ignorance. but besides that negative argument concerning the insolubility of crystal, by which the erroneous suppositions of naturalists are to be rejected, crystal in general is found regularly concreted in the cavities of the most solid rock, in the heart of the closest agate, and in the midst of granite mountains. but these masses of granite were formed by fusion; i hope that i shall give the most satisfactory proof of that truth: consequently, here at least there is no occasion for the action of water in dissolving siliceous substances in one place, in order to concrete and crystallise it in another. in these cavities of the solid granite rock, where crystal is found regularly shooting from a basis which is the internal surface of the cavity, we find the other constituent substances of the granite also crystallised. i have those small cavities, in this rock, from the island of arran, containing crystal, felt-spar, and mica, all crystallised in the same cavity[ ]. but this is nothing to the _druzen_ or crystalline concretions, which are found in a similar manner among metallic and mineral substances in the veins and mines; there, every species of mineral and metallic substance, with every variety of mixture and composition, are found both concreted and crystallised together in every imaginable shape and situation. [note : the chevalier dolomieu makes the following observation. journal de physique, juillet . "j'ai été étonné de trouver au centre d'un énorme massif de granit, que l'on avoit ouvert avec la poudre pour pratiquer un chemin, des morceaux, gros comme le poing et au dessous, de spath calcaire blanc, très-effervescent, en grandes écailles, ou lames entrecroisées. il n'occupoit point des cavités particulières, il n'y paroissoit le produit d'une infiltration qui auroit rempli des cavités, mais il étoit incorporé avec les feld-spath, le mica, et le quartz, faissoit masse avec eux, et ne pouvoit se rompre sans les entraîner avec lui." this great naturalist is convinced that the spar had not been here introduced by infiltration, although that is the very method which he employs to form concretions, not only of spar but of crystal, zeolite, and pyrites, in the closest cavities of the most solid rocks of basaltes. these four substances in this stone were so mixed together that nothing but the fusion of the whole mass could explain the state in which they appeared; but, thinking that such a supposition could not be allowed, this naturalist, like a man of science when his data fail, leaves the matter without any interpretation of his own. this however is what he has not done in the case of basaltes, or that which he mistakes for proper lavas, as i shall have occasion to show.] here is an infinite operation, but an operation which is easily performed by the natural arrangement of substances acting freely in a fluid state, and concreting together, each substance, whether more simple or more compound, directing itself by its internal principle of attraction, and affecting mechanically those that are concreting around it. we see the very same thing happen under our eye, and precisely in the same manner. when a fluid mass of any mineral or metallic substance is made to congeal by sudden cooling on the outside, while the mass within is fluid, a cavity is thus sometimes formed by the contraction of the contained fluid; and in this cavity are found artificial _druzen_, as they may be called, being crystallizations similar to those which the mineral cavities exhibit in such beauty and perfection. petrification and consolidation, in some degree, may doubtless be performed, in certain circumstances, by means of the solution of calcareous earth; but the examples given by m. de luc, of those bodies of lime-stone and agate petrified in the middle of strata of loose or sandy materials, are certainly inexplicable upon any other principle except the fusion of those substances with which the bodies are petrified[ ]. [note : vid. lettre et lettre . lettres physiques et morales.] this subject deserves the strictest attention; i propose it as a touchstone for every theory of petrification or perfect consolidation. first, there are found, among argillaceous strata, insulated bodies of iron-stone, perfectly consolidated; secondly, there are found, in strata of chalk and lime-stone, masses of insulated flints; thirdly, there are found, in strata of sea sand, masses of that sand cemented by a siliceous substance; fourthly, in the midst of blocks of sand-stone, there are found masses of loose or pure sand inclosed in crystallised cavities; and in this sand are found insulated masses of crystallised spar, including within them the sand, but without having the sparry or calcareous crystallization disturbed by it. there are also other globular masses of the same kind, where the sparry crystallization is either not to be observed, or appears only partially[ ]: and now, lastly, in strata of shell-sand, there are found masses of consolidated lime-stone or marble. in all those cases, the consolidated bodies are perfectly insulated in the middle of strata, in which they must of necessity have been petrified or consolidated; the stratum around the bodies has not been affected by the petrifying substance, as there is not any vestige of it there; and here are examples of different substances, all conspiring to prove one uniform truth. therefore, a general theory of petrification or consolidation of mineral bodies must explain this distinct fact, and not suffer it any longer to remain a _lusus naturae_. [note : mem. de l'académie royale des sciences, an. .] let us now consider what it is that we have to explain, upon the supposition of those concretions being formed from a solution. we have, first, to understand what sort of a solution had been employed for the introducing of those various substances; secondly, how those concretions had been formed from such solutions within those bodies of strata; and, lastly, how such concretions could have been formed, without any vestige appearing of the same substance, or of the same operation, in the surrounding part of the stratum. whatever may be the difficulty of explaining those particular appearances by means of fusion and mechanical force, it is plainly impossible to conceive those bodies formed in those places by infiltration, or any manner of concretion from a state of solution. naturalists, in explaining the formation of stones, often use a chemical language which either has no proper meaning, or which will not apply to the subject of mineral operations. we know the chemical process by which one or two stony concretions may be formed among bodies passing from one state to another. when, therefore, a change from a former state of things in mineral bodies is judged by naturalists to have happened, the present state is commonly explained, or the change is supposed to have been made by means of a similar process, without inquiring if this had truly been the case or not. thus their knowledge of chemistry has led naturalists to reason erroneously, in explaining things upon false principles. it would be needless to give an example of any one particular author in this respect; for, so far as i have seen, it appears to be almost general, every one copying the language of another, and no one understanding that language which has been employed. these naturalists suppose every thing done by means of solution in the mineral kingdom, and yet they are ignorant of those solvents. they conceive or they imagine concretions and crystallizations to be formed of every different substance, and in every place within the solid body of the earth, without considering how far the thing is possible which they suppose. they are constantly talking of operations which could only take place in the cavities of the earth above the level of the sea, and where the influence of the atmosphere were felt; and yet this is the very place which we have it in our power to examine, and where, besides the stalactite, and one or two more of the same kind, or formed on the same principle, they have never been able to discover one of the many which, according to their theory, ought always to be in action or effect. so far from knowing that general consolidating operation, which they suppose to be exerted in filling up the veins and cavities of the earth by means of the infiltrating water of the surface, they do not seem fully to understand the only operation of this kind which they see. the concretion of calcareous matter upon the surface of the earth is perhaps the only example upon which their theory is founded; and yet nothing can be more against it than the general history of this transaction. calcareous matter, the great _vinculum_ of many mineral bodies, is in a perpetual state of dissolution and decay, in every place where the influences of air and water may pervade. the general tendency of this is to dissolve calcareous matter out of the earth, and deliver that solution into the sea. were it possible to deny that truth, the very formation of stalactite, that operation which has bewildered naturalists, would prove it; for it is upon the general solubility of calcareous matter exposed to water that those cavities are formed, in which may be found such collections of stalactical concretion; and the general tendency of those operations is to waste the calcareous bodies through which water percolates. but how is the general petrifaction or consolidation of strata, below the surface of the sea, to be explained by the general dissolution of that consolidating substance in the earth above that level? instead of finding a general petrifying or consolidating operation in the part of the earth which we are able to examine, we find the contrary operation, so far at least as relates to calcareous spar, and many other mineral bodies which are decomposed and dissolved upon the surface of the earth. thus in the surface of the earth, above the level of the sea, no petrifying operation of a durable nature is found; and, were such an operation there found, it could not be general, as affecting every kind of substance. but, even suppose that such a general operation were found to take place in the earth above the level of the sea, where there might be a circulation of air and percolation of water, how could the strata of the earth below the level of the sea be petrified? this is a question that does not seem to have entered into the heads of our naturalists who attempt to explain petrifaction or mineral concretion from aqueous solutions. but the consolidation of loose and incoherent things, gathered together at the bottom of the sea, and afterwards raised into rocks of various sorts, forms by far the greatest example of petrification or mineral operation of this globe. it is this that must be explained in a mineral theory; and it is this great process of petrifaction to which the doctrine of infiltration, whether for the mechanical purpose of applying cohesive surfaces, or the chemical one of forming crystallizations and concretions, will not by any means apply. nothing shows more how little true science has been employed for the explanation of phenomena, than the language of modern naturalists, who attribute, to stalactical and stalagmical operations, every superficial or distant resemblance to those calcareous bodies, the origin of which we know so well. it is not a mere resemblance that should homologate different things; there should be a specific character in every thing that is to be generalised. it will be our business to show that, in the false stalactites, there is not the distinctive character of those water formed bodies to be found. in the formation of stalactical concretions, besides the incrustation as well as crystallization of the stony substance from the aqueous vehicle by which it had been carried in the dissolved state, we have the other necessary accompanyments of the operation, or collateral circumstances of the case. such, for example, is that tubular construction of the stalactite, first formed by the concretion of the calcareous substance upon the outside of the pendant gut of water exposed to the evaporation of the atmosphere; we then see the gradual filling up of that pervious tube through which the petrifying water had passed for a certain time; and, lastly, we see the continual accretion which this conducting body had received from the water running successively over every part of it. but among the infinite number of siliceous concretions and crystallizations, as well as those of an almost indefinite variety of other substances, all of which are attributed to solution, there is not the least vestige of any collateral operation, by which the nature of that concretion might be ascertained in the same manner. in all those cases, we see nothing but the concreted substances or their crystallizations; but, no mark of any solvent or incrusting process is to be perceived. on the contrary, almost all, or the greatest part of them, are so situated, and attended with such circumstances, as demonstrate the physical impossibility of that being the manner in which they had been concreted; for, they are situated within close cavities, through which nothing can pervade but heat, electricity, magnetism, etc.; and they fill those cavities more or less, from the thinnest incrustation of crystals to the full content of those cavities with various substances, all regularly concreted or crystallised according to an order which cannot apply to the concretion of any manner of solution. that there is, in the mineral system, an operation of water which may with great propriety be termed _infiltration_, i make no doubt. but this operation of water, that may be employed in consolidating the strata in the mineral regions, is essentially different from that which is inconsiderately employed or supposed by mineralists when they talk of infiltration; these two operations have nothing in common except employing the water of the surface of the earth to percolate a porous body. now, the percolation of water may increase the porousness of that body which it pervades, but never can thus change it from a porous to a perfect solid body. but even the percolation of water through the strata deposited at the bottom of the sea, necessarily required, according to the supposition of naturalists, must be refused; for, the interstices of those strata are, from the supposition of the case, already filled with water; consequently, without first removing that stagnant water, it is in vain to propose the infiltration of any fluid from the surface. this is a difficulty which does not occur in our theory, where the strata, deposited at the bottom of the sea, are to be afterwards heated by the internal fires of the earth. the natural consequence of those heating operations may be considered as the converting of the water contained in the strata into steam, and the expulsion of steam or vapour, by raising it up against the power of gravity, to be delivered upon the surface of the earth and again condensed to the state of water. let us now conceive the strata, which had been deposited at the bottom of the sea, as exhausted of their water, and as communicating with the surface of the earth impregnated with water. here again we have the power of gravity to operate in carrying down water to that place which had been before exhausted by the power of heat; and in this manner, by alternately employing those two great physical agents, we cannot doubt that nature may convey soluble substances from above, and deposit them below for the purpose of consolidating porous bodies, or of filling with saline and earthy matter those interstices which had been originally filled with water, when the strata were deposited at the bottom of the sea. how far any marks of this operation may be perceived, by carefully examining our mines and minerals, i know not; i can only say that, on the contrary, whenever those examined objects were clear and distinct, with the concomitant circumstances, so as to be understood, i have always found the most certain marks of the solid bodies having concreted from the fluid state of fusion. this, however, does not exclude the case of infiltration having been previously employed; and i would intreat mineralists, who have the opportunity of examining the solid parts of the earth, to attend particularly to this distinction. but do not let them suppose that infiltration can be made to fill either the pores or veins of strata without the operation of mineral heat, or some such process by which the aqueous vehicle may be discharged. not only are mineral philosophers so inconsiderate, in forming geological theories upon a mere supposition or false analogy, they have even proceeded, upon that erroneous theory, to form a geological supposition for explaining the appearances of strata and other stony masses in employing a particular physical operation, which is, that of _crystallization_[ ]. now crystallization may be considered as a species of elective concretion, by which every particular substance, in passing from a fluid to a solid state, may assume a certain peculiar external shape and internal arrangement of its parts, by which it is often distinguished. but, to suppose the solid mineral structure of the earth explained, like an enigma, by the word _crystallization_, is to misunderstand the science by which we would explain the subject of research; and, to form a general mineral theory thus upon that term, is an attempt to generalise without a reason. for, when it were even admitted that every solid body is crystallised, we thus know no more of the geology of this earth, or understand as little of the general theory of mineral concretion, as we did before;--we cannot, from that, say whether it be by the operation of solution or of fusion which had produced the perceived effect. [note : journal de physique; avril .] m. de carosi has wrote a treatise upon certain petrifactions[ ]. in the doctrine of this treatise there is something new or extraordinary. it will therefore be proper to make some observations on it. [note : sur la génération du silex et du quartz en partie. observations faites en pologne , à cracovie.] the object of this treatise is to describe the generation of silex and quartz, with their modifications or compositions, formed within mineral bodies of a different substance. the natural history contained in this little treatise is well described and sufficiently interesting. but it is chiefly in order to examine the means which, according to the theory of this treatise, are employed in petrifying bodies, that i consider it in this place. the first section of this treatise has for title, _génération du caillou et du quartz de la terre calcaire pure_. it may be worth while to compare the natural history of this part of the earth with the flint and chert found in our chalk and lime-stone countries. i shall therefore transcribe what is worth observing upon that subject (p. .). "nous rencontrons chez nous dans les parties le plus montagneuses, et les moins couvertes de terreau, ou tout-au plus de sable, entre de purs rochers calcaires une quantité incroyable de cailloux (silex) tant en boules, que veines, couches, et débris. au premier coup d'oeil l'on s'imagine que ce font des débris de montagnes éloignées, qui y furent amenés par les eaux, mais, en examinant la chose de plus pres, on est convaincu, que ce sont tout au contraire, des parties détachées des montagnes de la contrée. car il y a sur presque toute l'étendue de nos montagnes calcaires une couche, ou pour mieux dire, un banc composé de plusieurs couches de base calcaire, mais qui ou sont parsemées irrégulièrement de boules, de rognons, de veines, et de petits filons de silex, ou qui contiennent cette pierre en filon, veines, et couches parallèles, et régulièrement disposées. les boules et rognons de silex y font depuis moins de la grandeur d'une petite noisette, jusqu'au diamètre de plus de six pouces de nôtre mesure. la plupart de ces boules tant qu'elles sont dans l'intérieur caché de la roche vive, et qu'elles n'ont rien souffert de l'impression de l'air, ont, pour l'ordinaire, une croûte de spath calcaire, au moyen de la quelle elles sont accrues à la roche mere; ou pour mieux dire la croûte spatheuse fait l'intermède entre le silex, et la roche calcaire, par où se fait le passage de l'une à l'autre. mais ceci ne vaut que de boules de silex entièrement formées. c'est dont on peut même se convaincre à la vue, par beaucoup de pierres dont le pavé de la ville de cracovie est composé. mais là, ou le silex n'est pas encore entièrement achevé, la croûte spatheuse manque, en revanche on y voit évidemment le passage par degrés successifs de la roche calcaire au silex qui y est contenu, et les nuances de ce passage sont souvent si peu marquées que même les acides minéraux ne suffisent pas à les déterminer, ce n'est que le briquet, qui nous aide à les découvrir. on voit bien ou la pierre calcaire s'enfonce en couleur, l'on s'apperçoit, où sa dureté, ses cassures changent, mais, comme elle y souffre encore quelque impression des acides, l'on ne sauroit déterminer au juste le point, ou elle a déjà plus de la nature du silex, que de celle de la chaux, qu'en la frappant du briquet. "tels sont les cailloux en boules et rognons avant leur état de perfection, il y aura même au milieu une partie de pierre calcaire non changée. "ceux au contraire, ou la nature à achevé son ouvrage, ont une croûte de chaux endurcie, et sont purement du silex fini, mais de toutes couleurs, d'un grain et d'une texture plus ou moins fine, qui passe assez souvent par degrés dans les différentes variétés du noble silex. ils ont, pour l'ordinaire, dans leur intérieur une cavité, mais pas toujours au centre, et qui vient apparemment de la consommation de cette partie calcaire qui y resta la dernière, et n'en fut changée ou dissolute et séparée, que lorsque le reste du silex étoit déjà entièrement fini. ces cavités sont toujours, ou enduites de calcédoine en couche concentriques recouverte de petits cristaux fort brillans et durs de quartz, ou bien seulement de ces derniers-ci. par-fois il y a aussi du spath calcaire crystallisé, mais cela est extrêmement rare. quelque-fois enfin ces cavités sont remplies d'une noix de calcédoine. je n'ai réussi qu'une seule fois en cassant un pareil silex en boule d'y trouver encore le reste de l'eau de crystallisation." the only remark that i would here make is this, that, if the crystallization of those close cavities in the _silex_ had at any time required water of solution, it must always have required it. but, if there had been water of solution contained in those close cavities, for the crystallization of the various things which are often found within them, how comes it that this water is almost never found? i have good reason to believe that water contained within a solid flint will not make its escape, as does that contained in the _anhydrites_ of mount _berico_, which are composed of a porous calcedony. but the siliceous crystallizations within close cavities is a curious subject, which we shall have occasion to examine more particularly in treating of agates. we now proceed to the next section, which is the generation of silex and quartz in marl, (p. .) "il y a des contrées, chez nous, qui out des étendus assez considérables en long et en large, de montagnes de pierre de marne calcaire, dans lesquelles on rencontre le même phénomène que dans celles de chaux pure; c. a. d. nous y trouvons du silex de différentes variétés, et dans tous les degrés successifs de leur formation, et de leur perfection. outre cela, nous y voyons encore quelque chose, qui semble nous conduire à la découverte des moyens, dont se sort la nature pour effecteur cette opération, et qui nous étoit caché dans les montagnes de chaux pure: ces bancs de pierre marnesilicieuse, contiennent une partie considérable de pyrites sulfureuses, qui non seulement y forment une grande quantité de petits sillons, mais toute la masse de la montagne est rempli de parcelles souvent presqu'imperceptibles de ce minéral. ces pyrites sont évidemment des productions du phlogistique et de l'acide contenu dans la montagne. "l'eau, qui s'y trouve ordinairement en assez grande abondance, en détacha, extraha d'un et l'autre, et les combina après tous les deux ensemble. cette même eau les dissout derechef, et en fait de nouvelles combinaisons. c'est ce qu'on voit évidemment là, ou la nature, ayant commencé ses opérations, il n'y est resté de la pyrite, qu'une portion de la partie inflammable liée à une base terrestre. dans ces endroits la marne n'est que fort peu sensible aux acides, et de blanche qu'elle étoit, sa couleur est devenue presque noire. c'est là qu'on observe les différens degrés du changement de la marne en silex, contenant, même encore, par fois, de parties pyritéiques non détruites dans son intérieur. et comme la nature forme ici, de même, que dans la chaux pure les silex, la plupart en boules ou rognons; comme les différent degrés de métamorphoses de la marne en silex, sont ici beaucoup plus nombreuses que là, de sorte qu'il y a des bandes entières, qui mériteroient plutôt d'être appellés bandes silicieuses, que marneuses; comme il y a, enfin, une grande quantité de pyrites, qu'ailleurs, il est très probable qu'elle se serve là du même moyen qu'ici pour opérer la métamorphose en question. "ne nous précipitons, cependant, pas à en tirer plus de conséquences; poursuivons plutôt le fil de notre récit. "le silex, qui se trouve ici, est non seulement de différents degrés de perfection, il est de plus d'une espèce. il y a de la pierre à feu, de la calcédoine, des agathes, et différentes nuances et passages des espèces ordinaires aux fines du silex. "la pierre à feu, est, ordinairement dans son état de perfection d'un grain assez fin, d'une couleur grise plus ou moins foncée, et même donnant, dans le noirâtre, plus ou moins diaphane; ses cassures sont concentriques ou coquillées, et sa masse est assez compacte. outre sa conformation ordinaire en boules et rognons, elle fait presque toujours la noix de ursins marins, qui y font en grand nombre, et dont la coquille est le plus souvent, et presque toujours de spath calcaire, même au milieu d'une boule de silex parfait. "les calcédoines et agathes de ces couches sont toujours (au moins, je ne les ai pas encore vues autrement) de coraux et autres corps marins pétrifiés. donc, il faut que les couches de pierres roulées, d'où j'ai tiré ma collection citée plus haut, soyent des débris de montagne» détruites de cette espèce. il y en a qui sont très parfaites comme celles qui composent ma collection, d'autres méritent plutôt d'être rangées parmi les passages du silex ordinaire, et ses espèces plus fines; d'autres encore sont, en effet, de vraies agathes, mais qui renferment dans leur intérieur plus ou moins de parties non parfaites presque calcaires, qui s'annoncent d'abord par leur couleur blanche, par leur gros grains relativement au reste, par leur opacité, par leur mollesse respective, et souvent même par leur sensibilité pour les acides minéraux. mais celles, qui sont finies, quoiqu'elles ayent, pour la plupart, une couleur presque noire, ne laissent, cependant, pas d'avoir aussi des teintes plus claires comme brunâtres, verdâtres, rougeâtres, jaunâtres, bleuâtres, tachetées, veinées, etc. leur clarté n'est pas moins variable, que leur couleur, il y en a de presqu'opaques, comme aussi de presque transparentes, sur tout là, ou la calcédoine prédomine. "le quartz s'y trouve comme dans les pierres de la première section, c, a, d, crystallisé, en groupes dans de petites cavités; quelquefois aussi en veines. la calcédoine y est de même, ou bien en mamelons, ou bien en stalactites, lorsqu'elle a de la place pour s'y déposer. "un phénomène encore plus curieux que cela est cette belle pyrite sulphureuse jaune, comme de l'or, qui est quelquefois parsemée par tout la substance de pétrifications agathisées, et qui apparemment y fut déposée après la dite métamorphose à la faveur des petits pores, qui y étoient restés ouverts." i would beg that mineralists, who use such language as this, would consider if it contains a distinct idea of the operation which they would thereby describe, or if it does not contain either a contradiction or an inconceivable proposition. it supposes a calcareous body to be metamorphosed, somehow by means of the mountain acid, into a siliceous body. but, finding many bodies of pyrites contained within that solid flint, it is said, that, when the calcareous body was flintified, there were left in it cavities which were afterwards filled with pyrites. let us reflect a moment upon this doctrine. these cavities were first open to the outside of the flinty body; but now the pyrites with which they had been filled is insulated in the solid flint. here three things are required; first, the calcareous body is to be flintified, at the same time leaving the body full of small cavities open to the outside; secondly, these cavities are to be filled with pyrites; lastly, these mineral bodies are to be so inclosed within the flint, as to leave no vestige of the former processes. this marly mountain itself, which had been formed of loose materials gathered together at the bottom of the sea, was first to be filled with pyrites, in various shapes, by means of the phlogistic and the acid of the mountain. here is proposed to us an operation which is totally unknown, or of which we have no kind of idea. but, let us suppose pyrites formed in this mountain, (of whatever chemical substances), by means of water; why should water again undo that pyrites, in order to form other concretions? and, why should the flint be formed first with cavities, and then made solid, after pyrites had been introduced into those cavities of the agate, and, as our author expresses it, _parsemée pour toute la substance?_ here are suppositions which are not only perfectly gratuitous, but are also inconsistent with any thing that we understand. this is not explaining nature; it is only feigning causes[ ]. [note : the description of those insulated siliceous bodies, containing in their closed cavities all the usual concretions of calcedony and crystals, as well as full of small pyrites floating in the solid flint, are extremely interesting to a mineral system, or such a geological theory as should explain the present state of things in those strata that had been formed by deposits of known materials at the bottom of the sea; they are indeed such appearances as may be found, more or less, in all consolidated strata. but it is this author's explanation of that petrifaction which is our present object to consider; and, as he is so particular in giving us his theory upon the subject, it is easy to detect the error of his reasoning. were those naturalists who explain things only in general, by saying that water is the agent, and infiltration the means employed by nature;--were these naturalists, i say, to give us as particular a description of their process, it would appear as inconsistent with the nature of things as that which we have from this author, who examines nature very minutely, and who sees distinctly that the infiltrating theory is inapplicable for the explanation of those petrifactions.] the third section has for title, "_generation du silex et quartz de la pierre puante_." here we find an example worthy of being recorded, as contributing to throw great light upon those mineral operations; however, the opinion of our author and mine, upon this subject, differ widely. he proceeds thus: "cette pierre n'est, comme chacun le sçait, qu'une pierre calcaire contenant du bitume. "nos montagnes n'en contiennent seulement pas de simples couches, mais il y en a même de grandes bancs fort épais. "le caillou, ou silex qui s'y génère, forme, tantôt de gros blocs informes, qui occupent des cavités dans l'intérieure des montagnes, tantôt, enfin, en forme de filons. "j'ai remarqué cette métamorphose sur trois endroits différens, dans chacun des quels la nature a autrement opéré. "sur l'un, la pierre puante fait un banc horizontal dans une montagne de pierre calcaire crystalline, ou d'une espèce de marbre, qui contient des couches et filons de métal. ce banc de pierre puante y fait le toit d'une couche de galène de plomb et de pierre calaminaire, et dans ses cavités et fentes il y a non seulement des blocs de grandeur différente, mais aussi des veines et petites bandes courtes de silex, tant ordinaire, que noble c, a, d, de la pierre à feu, de calcédoine, d'agathes, et même d'une espèce de cornaline jaune et rouge pâle. je ne m'arrêterai pas à en détailler les variétés, parce qu'elles sont trop accidentelles. je ne les connois pas même toutes, il s'en faut de beaucoup, parce qu'elles se trouvent dans des anciennes mines négligées, peut être depuis plus d'un siècle, et par conséquent peu accessibles. je ne doute, cependant pas, que, si l'on pouvoit mieux sonder le terrain, on y trouveroit bien plus encore du peu que j'ai cité. parmi ce silex, il y a aussi de petites groupes et de petites veines de quartz solide et crystallisé. "au second endroit la pierre puante fait un filon, ou si l'on veut, une couche ou bande verticale, qui partage la montagne en deux parties presqu'égales de l'épaisseur de trois aunes à peu près. la montagne, ou cela se voit est aussi une ancienne mine de cuivre et de plomb, consistant en plusieurs variétés de marbre, différent en couleur et en grain, déposées par couches les unes sur les autres. le filon de silex est formé de feuilles alternatives de pierre puante et de silex, tous les deux de couleur brun de bois à peu prés; mais le silex est plus foncé que sa compagne. ces feuilles alternatives, consistent d'autres bien plus minces encore, qui souvent n'ont pas l'épaisseur d'une ligne, mais ce qu'il y a de plus curieux, c'est que la même feuille est d'un but de pierre porque, qui, vers le milieu, passe successivement en silex, qui, à son tour, vers l'autre but, qui étoit exposé à l'air repasse par les mêmes gradations en une espèce de tuffe calcaire. ce qui nous fait voir évidemment la génération et la destruction du silex, même avec une partie des moyens par lesquels elle s'opère. comme l'endroit de cette découverte n'est accessible qu'à la superficie, je ne saurois dire s'il y a d'autres variétés de silex outre la dite. il l'est à supposer autant par analogie, que par quelques morceaux qui ont de petites veines transversales d'une espèce de calcédoine, et qui sont, même, sur leur fentes, garnis de petits cristaux de roche. mais ce qu'il y a de sur c'est que ce filon, parvenu à une certaine profondeur, s'ennoblit et contient du métal, c. a. d. de la galène de plomb, et de la pyrite cuivreuse, j'y en ai trouvés de morceaux, qui en font de preuves incontestables. le caillou d'ici est un grain fin d'une texture forte, peu transparent, donne beaucoup d'étincelles au briquet, mais ses cassures sont écailleuses. "la montagne calcaire du troisième lieu a une couche de pierre puante épaisse de plusieurs aunes, qui, derechef contient de petites couches irrégulières et des bandes transversales de silex, qui ont jusques â six pouces passés d'épaisseur. la pierre puante est d'une couleur gris-brune, d'un grain assez fin, et d'un tissu assez dur; ses cassures sont irrégulières, mais plus la pierre s'approche du silex, plus elles donnent dans le coquillé. le silex ordinaire est d'un brun de bois, d'un grain assez fin, et d'un tissu résistant, et ses cassures sont égales à la pierre porque. ce n'est pas là la seule variété, il y a, aussi, de la calcédoine et des agathes de couleurs différentes. même la pierre à feu est assez souvent traversée de veines de calcédoine, de quartz crystallisé, et de spath calcaire blanc en feuilles et en crystaux. il arrive que la même veine est composée de ces trois espèces de pierres à la fois, de sorte que l'une semble passer dans l'autre, parce que les limites réciproques sont, souvent, assez indistinctes. il est évident, que le silex est formé de la pierre puante, parce qu'on remarque ici les mêmes phénomènes dont j'ai parlé plus haut, c. a. d. les passages successifs de l'une dans l'autre pierre, tant en montant qu'en descendant." there is nothing particular in the siliceous mixture in this species of lime-stone, except the vein of that substance. it is evident that this vein, traversing the mountain, had been introduced in the fluid state of fusion. i do not mean to say, that, in this particular case now described, the evidence of that truth peculiarly appears; but that, from the general nature of mineral veins breaking and traversing the solid strata of the globe, no other conclusion can be formed; and that in the particulars of this example there is nothing that could lead us to suppose any other origin to the petrifactions contained in this vein of stinking lime-stone. it is plain, that our author has imagined to himself an unknown manner of executing his mineral metamorphoses. he sees plainly that the common notion of infiltration will not at all explain the evident confusion of those calcareous and siliceous bodies which appear to him to be metamorphosing into each other. nothing, indeed, can explain those phenomena but a general cause of fluidity; and there is no such general cause besides that of heat or fusion. but to show how mineralists of great merit, gentlemen who have examined systematically and with some accuracy, may impose upon themselves in reasoning for the explanation of mineral appearances from limited notions of things, and from the supposition of these having been formed where they now are found, that is, upon the surface of the earth, i would beg leave to transcribe what this author has said upon this species of petrifaction. it is not that he is ignorant of what mineralists have already said upon the subject; it is because he sees the incompetency of their explanations in those particular cases; and that he would employ some other more effectual means. (p. .) "toute terre calcaire à changer dans une autre doit, avant toute chose, être rendue réfractaire ce qui ne peut se faire qu'en la saturant avec un acide. mais une terre simplement, saturée d'un acide, est d'une réduction fort aisée, vu que l'acide n'y tient pas trop fort, d'ailleurs ce n'est qu'un sel neutre terreux fort facile â dissoudre dans une quantité suffisante d'eau. or pour rendre cette union plus constante, il faut que la terre alcaline s'assimile intimement à l'acide, ce qui ne se sera jamais sans un intermedeliant, qui homogène les parties de ce nouveau corps, et pour que cela ce fasse il est indispensable, qu'il s'opère une dissolution foncière des parties terrestres de la chaux, qui facilite l'ingress à l'acide, et à l'intermède pour qu'ils s'y lie bien fortement. supposons qu'il se forme une liqueur savonneuse de l'acide et du phlogistique, que l'air fixe, mis en liberté, ouvre les interstices des parties qui constituent la terre alcaline, qu'apres cela cette liqueur savonneuse ayant l'entrée libre s'assimile à la terre en proportion requise, que l'eau, qui servoit de véhicule dans cette operation, s'évapore successivement, et emporte le superflu des ingrediens, pour qu'il se puisse opérer le rapprochement le plus exacte des parcelles ou molécules homogénées de nouveau corps qu'enfin les molécules les plus pures et les mieux affinées soyent réunies en forme liquide dans des cavités, et que par l'évaporation et séparation de l'eau, ou elles nageoient, il s'en forme des crystaux n'aurons-nous pas une boule de silex, avec de crystaux de quartz dans ses creux intérieurs." the supposed case is this; a calcareous body is to be metamorphosed into a siliceous nodule, having a cavity within it lined with quartz, crystals, etc. m. de carosi means to inform us how this may be done. now, as this process requires no other conditions than those that may be found upon the surface of this earth, the proper way to prove this hypothetical theory, would be to exhibit such a mineral body produced by those means. but, even supposing that such a process were to be exhibited, still it would remain to be explained, how this process, which requires conditions certainly not be found at the bottom of the sea, could be accomplished in that place, where the strata of the earth had been deposited, accumulated, consolidated, and metamorphosed. this mineral process, which has been now described, will no doubt revolt the opinions of many of our chemists as well as naturalists; and i should not have thought of transcribing it, but as an example of that inconclusive reasoning which prevails in mineralogical writings upon this subject. but this is not all. we have, upon this occasion, a most remarkable example of the fallaceous views that may be taken of things; and of the danger to science when men of sense and observation form suppositions for the explanation of appearances without that strict conformity with the principles of natural philosophy which is requited on all occasions. both m. de carosi, and also m. macquart[ ], to whom our author communicated his ideas and proper specimens, assert, that from their accurate experience, they find calcedony growing daily, not only in the solid body of gypsum, etc. while in the mine, but also in the solid stone when taktn out of the mine, and preserved in their cabinet. [note : vid. essais de minéralogie par m. macquart.] what answer can be made to this positive testimony of these gentlemen, by a person who has not seen any such a thing, and who has not the opportunity of examining the cases in which those naturalists may have perhaps been led into some delusion? were i however to conjecture upon a subject in which i have not any positive information, i should suppose that some part of the calcedony, like the _oculus mundi_ when dipped in water, may be so transparent, while containing some portion of humidity, that it is not easily distinguishable from the gypsum in which it is concreted; but that in having the humidity evaporated, by being taken out of the mine and exposed to the dry air, those portions of calcedony, which did not before appear, may be perceived by becoming more opaque[ ]. [note : from the description given in this treatise, and from the drawings both of m. de carosi and m. macquart, i find a very valuable inference to be made, so much the more interesting, as i have not found any example of the like before. this arises from the intimate connection which is here to be perceived between agate and gypsum. now, upon this principle, that the agate-calcedony had been formed by fusion, a truth which, from the general testimony of minerals, i must presume, it is plain, that those nodules of gypsum had been in the fluid state of fusion among those marly strata, and that the gypseous bodies had been penetrated variously with the siliceous substance of the calcedony. the description of those siliceous penetrations of gypsum is followed by this conclusion: "en voila assez, je crois pour faire voir que le silex ci-décrit est effectivement une émanation du gypse, et non pas une matière hétérogène amenée d'autre part et déposée, ou nous la voyons." in this instance our author had convinced himself that the calcedony concretions had not been formed, as he and other mineralists had before supposed, by means of infiltration; he has not, however, substituted any thing more intelligible in its stead. i do not pretend that we understand mineral fusion; but only that such mineral fusion is a thing demonstrable upon a thousand occasions; and that thus is to be explained the petrification and consolidation of the porous and naturally incoherent strata of the earth.] there is, however, a subject in which i can more freely accuse this author of being deceived. this naturalist says, that calcareous stones become silex by a certain chemical operation; and that those flinty bodies, in being exposed upon the surface of the earth, out of their natural bed, are again, by a contrary chemical operation, changed from flint to a calcareous substance. i will give it in his own words, (p. .) "cela dit, venons au fait. tout silex progénéré de chaux, détaché de son lieu natal, et exposé aux changemens de saisons, s'amollit, reçoit de crevasses, perd sa transparence, devient, enfin, tout-à-fait opaque, le phlogistique s'en évapore, l'acide en est détaché, lavé, et de terre vitrescible, qu'il étoit, il redevient chaux, comme il étoit auparavant." here is no question with regard to mere opinion, but to matter of fact; and, in this case, nothing is more evident, than that upon the surface of this earth, that is, in the examinable parts above the level of the sea, there is no transition either of calcareous bodies into flint, nor of flinty bodies into calcareous substance. calcareous matter is constantly dissolved by water, when it is exposed to the washing of that fluid; and it is even dissolved out of the most perfect union or combination with siliceous substance, and the most solid composition of an insoluble body, as may be perceived in the decaying of feld-spar. a superficial view of flints, which have come out of a body of chalk, may have created such an opinion, which will not either bear the light of chemical or mineral investigation. the subject of these chalk flints will be minutely examined in its proper place. our author has carefully examined the subject of flintification; and the country where he makes his observations would seem to be well disposed for such a research. he has had great opportunity and inclination to examine the subject which he writes upon; and he has given a distinct account of what be has seen. his description of the flintification of sand-stone is extremely interesting. i will therefore transcribe it, both as a valuable portion of natural history, and also in order to contrast this author's opinion, with regard to the means employed by nature in petrifying bodies, and that which i maintain to be the general consolidating operation of the globe. it is section v. _generation du caillou du silex du grès, ou pierre sablonneuse_. "tout grès est susceptible de cette métamorphose quant au grain et quant à la couleur; depuis la bréccia quartzeuse jusqu'à la pierre à rasoir; et depuis le grès blanc jusqu'au brun et presque noirâtre, tient ou non tient, dur, ou presque friable, c'est indifférent, toutes ces variétés donnent du silex, et surtout de la calcédoine, de la cornaline, et des agathes. quant au ciment je l'y ai toujours remarqué calcaire et faisant effervescence avec les acides dans les endroits de la pierre qui n'étoient point encore changés; et jamais je n'ai vu ce changement dans du grès dont le ciment fut ou quartzeux ou argileux et réfractaire. ainsi le ciment entre pour quelque chose dans ce changement. "le commencement de cette métamorphose paroit (autant que j'ai pu l'observer dans mes débris roulés) se faire par le ciment, qui dissout là, où les agens eurent l'accès libre, rend les grains en quartz mobiles, les emporte, les mêle avec sa masse dense-liquide, les dissout, même en partie, et forme, dans cet état, des veines et de masses calcédonieuse, carneoliques, ou d'une autre espèce de silex, au milieu du grés peu, ou pas du tout, changé. car autant que je puis voir, ce n'est pas par couches ou veines qu'elle s'opère, mais par boules et masses rond-oblongues. au commencement ces veines et tâches sont fort minces, et le reste du grés n'est point du tout, ou à peine sensiblement changé hormis qu'il gagne, plus de consistence, à proportion du changement souffert. mais à mesure que le silex y augmente et se perfectionne, on y apperçoit les degrés par lesquels a passé cette operation. les nuance du passage d'une pierre à l'autre deviennent plus visibles, les veines et masses de silex grandissent au point, même, qu'il y a jusqu'aux trois quart du grés changé en silex clair comme de l'eau n'ayant que fort peu de grains de sable nageants dans sa masse. des morceaux de cette espèce sont rares à la vérité, mais j'en ai, cependant, trouvé quelques uns. ordinairement, dans les beaux morceaux, le silex fait la base, et le sable y est, comme nageant tantôt en grains séparés tantôt en parties et flocons. dans les pieces moins belles, le sable fait la base, et le silex sert à la fois de ciment, et forme aussi plus ou moins de veines, qui traversent la masse en maintes et maintes directions. mais si c'est un grès à gros grains, ou de la bréccia, alors le reste prend la nature silicieuse mêlé de sable fin, et les gros grains de quartz restent tels, qu'ils étoient, sans changer. j'ai déjà remarqué que cette métamorphose semble s'opérer, comme celle des cailloux d'origine calcaire en forme approchans la sphérique, il faut encore y a jouter, que j'ai lieu de croire, qu'elle se fasse aussi du dedans en dehors, tout, comme la décomposition se fait du dehors au dedans. "il arrive dans cette pierre, comme dans toute autre, qu'il se forme des crystallisations dans les cavités. lorsqu'elles sont de silex, leur figure est toujours mamelonnée, mais leur eau ou pureté, leur grandeur et leur couleur n'est pas par tout égale. il y en a qui sont grands, et de la plus pure calcédoine, d'autres sont petits et chaque goutte ou mamelon contient un grain de sable, de facon que cela a l'air d'un grès crystallisé en mamelons ou stalagmitique. d'autres encore sont, de calcédoine, mais recouverts d'une croûte, tantôt blanche qui fait effervescence avec l'acide minéral, et qui est, par conséquent, de nature calcaire; tantôt cette croûte est bleue foncée nuancée de bleu-celeste; tantôt, enfin, elle est noire, mais toutes les deux réfractaires. outre ces crystallisations silicieuses, il y en a, quoique rarement, de quartzeuses, qui ou forment de petites veines de crystal, ou bien des groupes de crystaux quartzeux, ou qui enfin, enduisent les mamelons de silex." our author then makes a specification of the different varieties; after which he continues, p. . "après tout ceci, l'on conviendra j'espère, que nôtre grais est une pierre bien singulière, et surpassant, à bien des égards, le grais, faussement dit crystallisé, de fontainebleau. la raison de la figure du grais françois est fort évidente, c'est le spath calcaire, qui lui sert de ciment, qui la lui fit prendre; mais qu'est-ce qui opère les métamorphoses racontées dans notre grais siliceux? seroit-ce son ciment calcaire ou marneux par les mêmes raisons, qui font changer la marne en silex? la chose est très-probable, et je n'en saurois pas même, deviner d'autre. en ce cas la nature auroit un moyen d'opérer par la voie humide, ce que nous faisons dans nos laboratoires en quelque façon, par la voie sèche, c, a, d, de fondre et liquéfier la terre vitrescible, au moyen des alcalis; secret que nous lui avons déjà arraché en partie, en faisant la liqueur silicieuse." "je n'ose, cependant, décider pas même hypothétiquement, sur cette matière, pour n'avoir pu observer la nature dans ses ateliers, et parce que je ne possède que des pièces, qui détachées de leur lieu natal, depuis un très long-tems, furent exposées aux intempéries des saisons, où elles peuvent avoir souffert bien de changemens." there cannot be a more fair exposition of facts; and it is only our author's opinion of this mineral transmutation that i would controvert. i do not pretend to understand the manner of operating that our author here supposes nature to take. i only maintain, that here, as every where in general, the loose and incoherent strata of the globe have been petrified, that is, consolidated, by means of the fusion of their substances; and this i think is confirmed from the accurate description here given of the flintification of sand-stone. here is described very distinctly an appearance which is very common or general on those occasions; this is the parts or particles of stone floating in the fluid siliceous substance, and there dissolving more or less. m. de carosi describes very systematically the generation of silex, calcedony, onyx, and quartz, in calcareous earth, marl, gypsum, sand-stone, and also what he terms _terre glaise, ou de l'argile_. it is in this last that we find a perfect analogy with what is so frequent in this country of scotland. these are the agates, calcedonies, calcareous and zeolite nodules, which are found produced in our whin-stone or subterraneous lavas, that is, the amygdaloides of crondstedt. naturalists explain the formation of those nodular bodies differently. the chevalier de dolomieu supposes these rocks to have been erupted lavas, originally containing cavities; and that these cavities in the solid rock had been afterwards filled and crystallised, by means of infiltration, with the different substances which are found variously concreted and crystallised within the solid rocks. our author, on the contrary, supposes these formed by a species of chemical transmutation of calcareous and argillaceous earths, which, if not altogether incomprehensible, is at least not in any degree, so far as i know, a thing to be understood. this is not the place where that subject of these particular rocks, which is extremely interesting, is to be examined. we shall afterwards have occasion to treat of that matter at large. it is sufficient here to observe, that our author finds occasion to generalise the formation of those petrifactions with the flintifications in calcareous and gypseous bodies. when, therefore, the formation of any of them shall be demonstrated, as having taken its origin in the fusion of those substances, this mode of operation, which is generalised in the consolidation of strata, will be properly inferred in all the rest. petrifaction is a subject in which mineralogists have perhaps wandered more widely from the truth than in any other part of natural history; and the reason is plain. the mineral operations of nature lie in a part of the globe which is necessarily inaccessible to man, and where the powers of nature act under very different conditions from those which we find take place in the only situation where we can live. naturalists, therefore, finding in stalactical incrustation a cause for the formation of stone, in many respects analogous to what is found in the strata of the earth, and which had come from the mineral region in a consolidated state, have, without due consideration, attributed to this cause all the appearances of petrifaction or mineral concretion. it has been one of the objects of this work to show that this operation of incrustation, or petrifaction by means of solution, is altogether ineffectual for producing mineral concretions; and that, even were it capable of forming those mineral bodies, yet that, in the solid parts of this earth, formed by a deposit of travelled materials at the bottom of the sea, the conditions necessary to this incrustating process do not take place. those enlightened naturalists who have of late been employed in carefully examining the evidences of mineral operations, are often staggered in finding appearances inconsistent with the received doctrine of infiltration; they then have recourse to ingenious suppositions, in order to explain that enigma. in giving examples of this kind. i have in view both to represent the natural history these mineralists furnish us with, which is extremely interesting, and also to show the various shapes in which error will proceed, when ingenious men are obliged to reason without some necessary principle in their science. we have just now had an example in europe; i will next present the reader with one from asia. m. patrin, in his _notice minéralogique de la daourie_, (journal de physique, mars ) gives us a very distinct account of what he met with in that region. describing the country of doutchersk upon the river argun, in siberia, he proceeds thus: "ces colines sont formées d'un hornstein gris qui paroit se convertir en pierre calcaire par l'action des météores; car tout celui qu'on prend hors du contact de l'air donne les plus vives étincelles, et ne fait pas la moindre effervescence avec les acides, même après avoir été calciné; et l'on observe celui qui est à découvert, passer, par nuances insensibles, jusqu'à l'état de pierre calcaire parfaite de couleur blanchâtre." here m. patrin has persuaded himself, probably from an imperfect examination of the subject, that there takes place a mineral metamorphosis, which certainly is not found in any other part of the earth, and for which he does not find any particular cause. the natural effect of the meteors, in other parts of the earth, is to dissolve the calcareous substance out of bodies exposed to those agents; and the gradation from the one of those two things to the other, which seems to be the data on which he had proceeded in forming his conclusion, is not sufficient to prove the metamorphosis, even were there not so strong a physical objection to it; for, it is by no means unusual for mineral bodies to graduate thus from one substance to another. however that be, this is not the principal object of the example[ ]. [note : here we have well informed naturalists reasoning with all the light of our present mineralogy, and maintaining, on the one hand, that gypsum is transformed into calcedony, by the operation of the meteors, or some such cause; and, on the other, that a siliceous substance is by the same means converted into lime-stone. what should we now conclude from this?--that calcareous and siliceous substances were mutually convertible. but then this is only in certain districts of poland and siberia. every where, indeed, we find strange mixtures of calcareous and siliceous bodies; but neither mineralists nor chemists have, from these examples, ventured to affirm a metamorphosis, which might have spared them much difficulty in explaining those appearances. this is a subject that may be taken in very different lights. in one view, no doubt, there would appear to be absurdity in the doctrine of metamorphosis, as there is now a days acknowledged to be in that of _lusus naturae_; and those reasoning mineralists might thus, in the opinion of some philosophers, expose their theory to contempt and ridicule. this is not the light in which i view the subject. i give those gentlemen credit for diligently observing nature; and i applaud them for having the merit to reason for themselves, which would seem to be the case with few of the many naturalists who now speak and write upon the subject. let us now draw an inference, with regard to this, in judging of the different theories. either the received system concerning mineral operations is just, in which case those gentlemen, who employ a secret metamorphosis, may be to blame in laying it aside; or it is erroneous and deficient; and, in that case, they have the merit of distinguishing the error or deficiency of the prevailing system. how far they have seen the system of nature, in those examples which they have described, is another question. in the mean time, i am to avail myself of the testimony of those gentlemen of observation, by which the insufficiency at least of the received mineral system is acknowledged.] after speculating upon the effect of the ancient ocean upon the mountains of that country, he proceeds as follows: "je laisse ces conjectures pour remarquer un fait singulier: la colline, qui est au nord de l'église de la fonderie, a son arrête composée de ce hornstein qui se décompose en pierre calcaire; mais ici, les parties, qui sont ainsi décomposées, offrent une substance calcédonieuse disposées par zones concentriques, comme on l'observe dans les agates d'oberstein; mais ce ne sont point ici des corps parasites formés par infiltration dans des cavités pré-existantes comme les agates; on voit que ce sont les parties constituantes de la roche qui, _par un travail interne_, et par une sorte de crystallisation, out pris cette disposition régulière (que ce mot de _crystallisation_ ne révolte point, j'appelle ainsi toute tendance à prendre une forme constante, polyèdre ou non polyèdre.) les couches les plus voisine du centre sont nettes et distinctes; peu-à-peu elles le sont moins, et enfin elles s'évanouissent et se confondent avec le fond de la roche. chaque assemblage de ces zones a une forme ronde ou ovale plus ou moins régulière de sept à huit pouces de diamètre. "cela ressemble en grand à ce qu'on observe dans les pierres oeillées, et la cause est vraisemblablement la même. je le répète, je regarde cette disposition régulière comme une véritable cristallisation, qui peut s'opérer et qui s'opère en effet dans l'intérieur des corp les plus solide, tant qu'ils sont fournis à l'action des agens de la nature. "tous ceux qui visitent l'intérieur de la terre savent que les roches mêmes le plus compactes y sont intimement pénétrées d'humidité, et ce fluide n'est certainement pas l'eau pure; c'est l'agent qui opère toutes les agrégations, toutes les cristallisations, tous les travaux de la nature dans le règne minéral. on peut donc aisément concevoir qu'à la faveur de ce fluide, il règne, dans les parties les plus intimes des corps souterrains, une circulation qui fait continuellement changer de place aux élémens de la matière, jusqu'a ce que réunis par la force des affinités, les corpuscules similaires prennent la forme que la nature leur a assignée." those nodular bodies or figured parts which are here inclosed in the rock, are evidently what may be called calcedony agates. m. patrin is persuaded, from the examination of them, that they had not been formed in the manner of german agates, which he supposes is by mean of infiltration; and he has endeavoured to conceive another manner of operating, still however by means of water, which i suppose, according to this hypothesis, is to dissolve substances in one part, and deposits them in another, there must certainly be some great _desideratum_ in that mineral philosophy which is obliged to have recourse to such violent suppositions. first, water is not an universal solvent, as it would require to be, upon this supposition; secondly, were water allowed to be an universal menstruum, here is to be established a circulation that does not naturally arise from the mixture of water and earth; and, lastly, were this circulation to be allowed, it would not explain the variety which is found in the consolidation and concretion of mineral bodies. so long, therefore, as we are to explain natural appearances by reasoning from known principles, and not by ascribing those effects to preternatural causes, we cannot allow of this regular operation which m. patrin alleges to be acting in the interior parts of the most solid bodies. this is indeed evident, that there has been a cause operating in the internal parts of the most solid bodies, a cause by which the elements, or constituent parts of those solid bodies, have been moved and regularly disposed, as this author very well observes must have been the case in our agates or eyed stones; but to ascribe to water this effect, or to employ either an ineffectual or an unknown cause, is not to reason philosophically with regard to the history of nature; it is to reason phantastically, and to imagine fable. m. monnet has imagined a petrifying power in water very different from any that has hitherto been conceived, i believe, by natural philosophers, and i also believe, altogether inconsistent with experience or matter of fact; but as it is not without good reason that this naturalist has been induced to look out for a petrifying cause different from any hitherto supposed, and as he has endeavoured very properly to refute the systems of petrification hitherto received, i would beg leave to transcribe his reasoning upon the subject in corroboration of the present theory of consolidation by the means of fusion. it is upon occasion of describing one of the species of alpine stone or schistus which contains quartzy particles. _nouveau voyage minéralogique, etc._ journal de physique aoust . "il y a loin de cette pierre, que je regarde comme une variété de roches ardoisées, aux véritable ardoises. la composition de toutes ces pierres est due aux terres quartzeuses et argileuses, et à la terre talqueuse, que je démontrerai un jour être une espèce particulière et distincte des autres, qui constitue les bonnes ardoises, et fait, ainsi que le quartz, qu'elles résistent aux injures de l'air, sans s'effleurir, comme je ferai voir que cette terre, qu'on désignera sous la dénomination de terre talqueuse, si l'on veut, résiste au grand feu sans se fondre. les différences de toutes ces pierres, quoique composées des mêmes matières, mais dans des proportions différentes, sont frappantes, et pourroient faire croire qu'elles n'appartiennent pas à ce genre. mais qui ne voit ici que toutes ces différences, ou ces variétés, ne sont dues qu'aux modifications de la matière première, qu'elle a éprouvées, soit en se mêlant avec des matières hétérogènes, prévenantes du débris des êtres qui ont existé, comme l'argile, par exemple, qui, de l'aveu de presque tous les naturalistes, est le produit de l'organization des plantes, ou soit en se mêlant avec de la matière déjà solidifiée depuis long-temps? or nous ne craignons pas de dire, ce que nous avons dit plusieurs fois quand l'occasion s'en est présentée, que cette matière unique, que se modifie selon les occasions et les circonstances, et qui prend un caractère analogue au matières qu'elle rencontre, est l'eau, que beaucoup de naturalistes cherchent vainement ailleurs. ils ne peuvent comprendre, malgré les exemples frappans qui pourroient les porter à adopter cette opinion, que ce fluide général soit l'élément des corps solides du règne minéral, comme il est de ceux du règne végétal et du règne animal. l'on cherche sérieusement, par des expériences chimiques, à découvrir si l'eau est susceptible de se convertir en terre comme si la nature n'avoit pas d'autre moyen que nous de la faire passer de l'état fluide à l'état solide. voyez le spath calcaire et le quartz transparens; est il à présumer qu'ils ne sont que le résultat du dépôt des matières terreuses fait par les eaux? mais, dans ce ca-là encore, il faut supposer que l'eau qui est restée entre ces partie s'est solidifiée; car, qu'est-elle donc devenue, et quel est donc le lien qui a uni ces parties et leur a fait prendre une forme régulière? il est vrai qu'on nous parle d'un suc lapidifique; mais c'est-la un être de raison, dont il seroit bien plus difficile d'établir l'existence, que de croire à la solidification de l'eau. on nous donne cependant comme un principe certain que l'eau charie d'un lieu à un autre les matières qu'il a dissoutes, et qu'elle les dépose à la maniere des sels. mais c'est supposer une chose démentie par l'experience; savoir, que l'eau ait la propriété de dissoudre les matières terreuses, telles que la quartzeuse. a la vérité, m. auchard de berlin y joint de l'air fixe; mais cet air fixe ne sauroit tenir en dissolution un atome de quartz dans l'eau; et quelle qu'ait été l'exactitude de ceux qui ont répété les expériences de m. auchard, on n'a pu réussir à imiter la nature, c'est-à-dire, à former des cristaux quartzeux, comme il a annoncé. que l'eau ait la faculté de tenir en dissolution quelques petites parties de terre calcaire, au moyen de cet air fixe, il n'en faut pas conclure qu'elle puisse former de cette maniere tous les cristaux calcaires, sans que l'eau elle-même y concoure pour sa part; car ce seroit conclure quelque fois que la partie seroit égale au tout. voyez ces géodes calcaire et argileuses, qui renferment des cristaux nombreux de quartz ou de spath calcaire; ne sont ils que le résultat du dépôt de l'eau qui y a été renfermée, ou que la cristallization pure et simple des molécules que vous supposez avoir été tenues en dissolution par cette eau? il naîtroit de cette opinion une foule d'objections qu'il seroit impossible de résoudre. cependant m. guettard, dans la minéralogie du dauphiné, qui vient de paroître, ouvrage très-estimable à beaucoup d'égards, explique, selon cette maniere de penser, la formation de cristallizations quartzeuses qu'on trouve dans certaines géodes de cette province, et celle des mines de cristal des hautes montagnes. en supposant même comme vraie l'explication qu'il en donne, on trouveroit en cela un des plus grands problème, et des plus difficiles à résoudre qu'il y ait en minéralogie; car d'abord il faudroit expliquer comment un si petite quantité d'eau que celle qui a été renfermée dans les géodes, et celle qui est parvenue dans les fentes des rochers, ont pu fournir un si grande quantité de matière que celle qui constitue ces cristallisations, et ce qui n'est pas le moins difficile à concevoir, comment l'eau a pu charrier cette matière à travers tant de matières différentes, et la conserver précisément pour cette destination; comment, par exemple, l'eau est venue déposer de la terre quartzeuse dans les masses énormes de pierres calcaires, qui forment la côté qui domine le village de champigny, à quatre lieues de paris, au delà de saint-maur; car s'il nous faut citer un exemple frappant de cette singularité, et à portée d'être vue des naturalistes qui sont dans la capitale, je ne puis mieux faire que de citer cette côté, une des plus curieuses de la france, et que je me propose de fair connoître en détail dans la troisième partie de la minéralogie de la france. on verra, dis-je, dans cette bonne pierre à chaux, et une de plus pure des environs de paris, de très-abondantes cristallisations de quartz transparent, et quelque fois de belle eau, que les ouvriers sont forcés de séparer de la partie calcaire, à laquelle elles adhèrent fortement. mais c'est trop nous arrêter à combattre une opinion qui doit son origine aux premières idées qu'ont eues les premiers observateurs en minéralogie, qui se détruira d'elle même comme tant d'autres dont il nous reste à peine le souvenir." we find here an accurate naturalist, and a diligent observer, who, in conformity with what my sentiments are upon the subject, thinks it impossible that the crystallizations in close cavities, and concretions of different solid substances within each other, which so frequently occur in the mineral regions, could have been produced, by means of solution and crystallization, from a fluid vehicle. but what has he now substituted in place of this solution, in order to explain appearances?--a mere supposition, viz. that nature may have the power of converting water, in those secret places, into some other thing; or rather that the substance of water is here converted into every other thing; for, though he has only mentioned quartz and calcareous spar, what mineral substance is there that may not be found in those close cavities? they are actually almost all, not even excepting gold; for, small grains of gold are inclosed within the cavities of a porous stone, in the siberian mine. now, for what purpose should nature, (to the power of which we are not to set a limit) have such an object in view as to convert water into every thing, unless it were to confound human understanding? for, so far as human experience has been as yet able to reach, there would appear to be certain elementary substances; and among these is water, or the principles of that fluid[ ]. but because water is so generally found in bodies, and so necessarily in most of the operations of this world, why convert it into every other thing? surely, for no better reason than that there has not occurred to this mineralist any other way of explaining certain natural appearances which aqueous solution could not produce. here is no dispute about a matter of fact; it is on all hands allowed, that in certain cavities, inaccessible to any thing but heat and cold, we find mineral concretions, which contain no water, and which, according to the known operations of nature, water could not have produced; must we therefore have recourse to water acting according to no known principle, that is to say, are we to explain nature by a preternatural cause? [note : water is now considered by men of science, as a compound substance; this doctrine, which seems to follow so necessarily from the experiments of the french philosophers, must be tried by the growing light of chemical science. in the oxygenating operation of inflammable and combustible bodies when burning, those ingenious chemists overlooked the operation of _phlogistic matter_, which has no weight, and which escapes on that occasion, as i have had occasion to show in a dissertation upon phlogiston, and in the philosophy of light, heat, and fire. how far this view, which i have given of those interesting experiments, may lead to the explanation of other collateral phenomena, such as that of the water produced, i will not pretend to conjecture. one thing is evident, that if the weight of the water, procured in burning inflammable and vital air, be equal to that of those two gasses, we would then have reason to conclude, either that water were a compound substance, or that vital air, and inflammable vapour were compounds of water and the matter of light, or solar substance.] i dare say that this is not the view that m. monnet takes of the subject, when he thinks to explain to himself the concretion of those different substances by means of water; but, according to my apprehension of the matter, his theory, when sifted to the bottom, will bear no other construction; and, unless he shall consider water like the matter of heat, as capable of producing the fluidity of fusion, and of being also again abstracted from the fluid, by pervading the most solid body, which would then be a substance different from water, he must employ this aqueous substance as a menstruum or solvent for solid bodies, in the same manner as has been done by those naturalists whom he he justly censure, and conform to those erroneous ideas which first observations, or inaccurate knowledge of minerals, may have suggested to former naturalists. it is the dissolution and concretion of siliceous substance, no doubt, that gives such difficulty to our naturalists in explaining petrifaction: they have, however, something apparently in their favour, which it may be proper now to mention. in the _first_ place, although siliceous substance is not soluble, so far as we know, by simple water, it is soluble by means of alkaline substance; consequently, it is possible that it may be dissolved in the earth. _secondly_, the water of giezer in iceland, actually petrifies bodies which are alternately imbibed with that hot water and exposed to the air. this water, therefore, not only contains siliceous substance in a dissolved state, but deposits this again, either by means of cooling, or being aerated, or of evaporating. consequently, without knowing the principle upon which it proceeds, we here perceive a natural operation by which siliceous petrifaction may be performed. _lastly_, we have another principle for the dissolution of siliceous substance. this is the fluor acid which volatilises the siliceous substance. this, however, requires certain conditions, which cannot be found as a general cause in the mineral regions. thus we would seem to have every thing necessary for explaining the concretion and crystallization of siliceous bodies, provided we could find the proper conditions requisite for that operation; for whether it shall be by means of acid or alkaline substances that siliceous matter is to be dissolved, volatilised, and transported from one place to another, it is necessary that those dissolving substances should be present upon those occasions. nor is it sufficient only to dissolve the siliceous substance which is to be transported; the necessary conditions for the concretion again of the dissolved substances, whatever these may be, are also absolutely required for this operation. now, though those requisite conditions may be, upon many occasions, allowed in the earth, it is not according to the theory of our modern naturalists, who explain petrifaction upon the principles of simple infiltration of water, that any advantage can be taken of those conditions; nor are natural appearances to be explained without employing more complicated chemical agents in the mineral regions. to this subject of the petrifactions of giezier, i may now add the information which we have received in consequence of a new voyage from this country to iceland. when sir joseph banks returned from his expedition to iceland, he landed at this place; and, having brought specimens of the petrifications of giezer, dr black and i first discovered that these were of a siliceous substance. i have always conjectured that the water of giezer must be impregnated with flinty matter by means of an alkaline substance, and so expressed my opinion in the theory of the earth published in the transactions of the edinburgh royal society. we have therefore been very desirous of procuring some of that water, in order to have it analysed. an opportunity favourable to our views has occurred this summer. mr stanley set out from this place with the same purpose of examining iceland. he was so good as to ask of dr black and i what inquiries we would incline that he should make. we have now, by the favour of this gentleman, obtained specimens of the petrifactions of giezer; and, what is still more interesting, we have procured some of the water of those petrifying boiling springs. it appears from these specimens, that the boiling water which is ejected from those aqueous volcanoes, if we may use the expression, is endued with the quality of forming two different species of petrifaction or incrustation; for, besides the siliceous bodies, of which we had before received specimens, the same stream of water incrustates its channel with a calcareous substance. all the specimens which i have seen consist of incrustation, some purely siliceous, some calcareous, and others mixed of those two, more or less. dr black has been analysing the water; and he finds in it siliceous matter dissolved by an alkaline substance, in the manner of liquor silicum[ ]. my conjecture has thus been verified. [note : see trans. of the edin. royal society.] it must not be alleged that nature may operate in the mineral regions, as she does here upon the surface in the case of giezer. such an argument as this, however sound it may be in general, will not apply to the subject of which we treat at present. there is no question about the limiting the powers of nature; we are only considering nature as operating in a certain determined manner, viz. by water acting simply upon the loose materials of the land deposited at the bottom of the sea, and accumulated in regular strata, one upon another, to the most enormous depth or thickness. this is the situation and condition of things in which nature is to operate; and we are to find the means of consolidating those strata, and concreting every species of substance in almost every possible composition, according to some known physical principle. here is an operation which is limited; for, we must reason strictly, according to the laws of nature, in the case which we have under consideration; and we cannot suppose nature as ever transgressing those laws. it is acknowledged, that, by means sometimes of an aeriform, sometimes of an alkaline, perhaps also of an acid substance, calcareous matter is dissolved in the earth, and certain metallic substances, such as lead and iron. this solution also, upon particular occasions, (where the proper conditions for separating the solvent from the dissolved substance exist), forms certain concretions; these are sometimes a mere incrustation, as in the case of the siliceous incrustation of giezer, sometimes again in a crystallised or sparry form, as in the case of stalactical concretions. but here is no question of those cases where the proper conditions may be found; first, of dissolving the substance which is afterwards to be concreted; secondly, of separating the menstruum from the dissolved substance; and, lastly, of removing the fluid deprived of its solution, and of supplying a new solution in its room; the question is, how far those concretions are formed where those conditions do not take place. now, this last case is that of almost all mineral concretions. it must not be here alleged that certain concretions have been found in mines posterior to these having been worked by man; consequently, that those concretions have been formed by nothing but the infiltration of water. in those cases, where such concretions are truly found, i am persuaded that all the conditions proper to that operation will also be found; and it is only, i believe, in those cases where such proper conditions may be found, that this aqueous concretion ever appears. now, if we shall except calcareous stalactite, and the bog ore of iron, how seldom is it that any appearance of those aqueous mineral concretion ever is found? those very few cases in which they are found, afford the strongest proof against these being operations general to the globe, or proper mineral concretions; because it is only where all the necessary conditions conspire in each contributing its part, that the effect is accomplished; and this is a thing which cannot possibly take place in the aquiform strata below the surface of the sea. but, without attending to this clear distinction of things perfectly different, naturalists are apt to see false analogies, and thus in generalising to form the most erroneous theories. i shall now give an example of this fallaceous manner of reasoning; it is in the case of certain mineral appearances which are erroneously considered as stalactical concretions. the only true stalactical bodies are of a calcareous substance; they are formed by water containing this substance in a dissolved state; and the principles upon which this particular concretion is formed are well known. it is therefore easy to compare other concretions, which may have some superficial resemblance to these stalactical bodies, in order to see if they have proceeded upon the same principle of concretion from a dissolved state, or by water depositing its dissolved substance in a similar manner. there are two different mineral substances which give appearances of this sort. these are certain concretions of calcedony, and also of iron-ore, which are thought to have such resemblance to stalactical concretions as, by some superficial observers, to be reckoned of the same kind. it is now proposed to show that those conclusions are not well founded; and that, in this case of calcedony and iron-ore, it could not be upon the principle of stalactical concretion that the bodies now in question had their forms. the principle upon which calcareous substance is dissolved in water, and made to concrete by the evaporation of the acid substance, or fixed air by which it had been dissolved, is too well known to require any explanation in this place; we are only to consider the sensible effects of those operations of which we know so well the proper conditions. there are just two distinct views under which we may consider all stalactical concretions formed; these are the incrustation of the calcareous substance concreting upon a foreign body, and the incrustation of the same substance upon itself. by the first any manner of shape may be formed, provided there be a solid body, upon the surface of which the calcareous solution is made to pass. by the second, again, we have various forms; but we know the principles upon which they had been made. these are the shape and motions of the fluid which gives the calcareous concretion. now, these principles are always to be perceived, more or less, in all the bizarre or fantastical, as well as regular shapes which are produced by stalactical concretions. at present, we shall confine our views to one particular shape, which is simple, regular, and perfectly understood wherever it is formed. drops of water falling from a roof, and forming stalactite, produce first tubular bodies, and then gradually consolidate and increase those pendulous bodies by incrustation. these appearances are thought to be observed in the calcedony and ferruginous concretions, which has led some mineralists to conclude, that those concretions had been formed in the same manner, by means of water. we are now to show that these mineral appearances are not analogous to stalactites in their formation, and that they have evidently been formed in a different manner. it must be evident, that, in the formation of those pendulous bodies, each distinct stalactite must be formed by a separate drop of water; consequently, that no more stalactites can be formed in a given space, than there could have subsisted separate drops of water. now, a drop of water is a very determined thing; and thus we have a principle by which to judge of those mistaken appearances. let us suppose the gut of water to be but one eighth of an inch, although it is a great deal more, we should have no stalactites formed nearer to each other than that measure of space. but those mineral concretions, which are supposed to be stalactical, are contained in half that space, or are nearer to each other than the tenth or twentieth of an inch. i have them like needles, and in every degree of proximity or contiguity, at the same time that they are perfectly solid. therefore, it is plainly impossible that they could have been formed upon this principle of calcareous stalactite. but, it is only by this false resemblance, that any argument can be formed for the concretion of those bodies from an aqueous solution; in every other respect they are true mineral concretions; and, that these have had a very different origin, has been already the subject of investigation, and will be more particularly examined in the course of this work. the term _infiltration_, which has been much employed for explaining mineral appearances, is too vague, imperfect, or unexplicit, for science, whether as the means of knowing nature, or the subject of confutation. this is not the case with that of stalactite; here is a term that implies a certain natural operation, or a most distinct process for attaining a certain end; and we know the principles upon which it proceeds, as well as the several steps that may be traced in the general result. it is an operation which has not only been analysed to its principles; it is also a process which is performed by man, proceeding on his acquired knowledge. now, were this operation common to the mineral regions, as it is proper to the surface of this earth; we could not remain in any degree of suspense with regard to the origin of those mineral bodies; for, having the true clue of knowledge, we should be able to unravel the most intricate and mysterious appearance. but, so far from this being the case, the more we come to inquire into nature, and employ this principle, the less we find it applicable, and the more involved in darkness is our science. the places where these false appearances of stalactite are found, are precisely those in which, from the nature of things, all possibility for such an operation is excluded. for, how can this take place within a closs cavity in the mineral regions? the term _vegetation_ may as well be employed for the explanation of those appearances: but what would now be said of such an explication? it is high time that science were properly applied to the natural history of this earth, and mineralists not allowed to impose upon themselves with false reasoning, or to please themselves with the vain attempt of explaining visible effects by unknown causes. such various inconsistent opinions, respecting petrifaction or mineral concretion, as i have now exposed, opinions that are not founded on any sound physical principle, authorise me to conclude that they are all erroneous. if this be admitted, it will follow that we have no proof of any proper mineral concretion except that which had proceeded by congelation from the fluid state of fusion. this has been the doctrine which i have held out in my theory of the earth; and this will be more and more confirmed as we come to examine particular mineral appearances. chap. viii. the nature of mineral coal, and the formation of bituminous strata, investigated. sect. i.--purpose of this inquiry. in the first chapter, i have given a perfect mark by which to judge, of every consolidated stratum, how far that had been the operation or effect of water alone, or if it had been that of heat and fusion. this is the particular veins or divisions of the consolidated stratum, arising from the contraction of the mass, distended by heat, and contracted in cooling. it is not an argument of greater or lesser probability; it is a physical demonstration; but, so far as i see, it would appear to be for most mineralists an unintelligible proposition. time, however, will open the eyes of men; science will some day find admittance into the cabinet of the curious. i will therefore now give another proof,--not of the consolidation of mineral bodies by means of fusion, for there is no mineral body in which that proof is not found,--but of the inconsistency of aqueous infiltration with the appearances of bodies, where not only fusion had been employed for the consolidation, but where the application of heat is necessary, and along with it the circumstances proper for _distillation_. short-sighted naturalists see springs of water issuing from the earth, one forming calcareous incrustations, the other depositing bituminous substances. here is enough for them to make the theory of a world; on the one hand, solid marble is explained, on the other, solid coal. ignorance suspects not error; their first step is to reason upon a false principle;--no matter, were they only to reason far enough, they would soon find their error by the absurdity into which it lands them. the misfortune is, they reason no farther; they have explained mineralogy by infiltration; and they content themselves with viewing the beautiful specimens in their cabinet, the supposed product of solution and crystalization. how shall we inform such observators; how reason with those who attend not to an argument! as naturalists have explained all mineral concretions from aqueous or other solution, and attributed to infiltration the formation of those stony bodies in which there are marks of their original composition, so have they explained to themselves, i suppose, the origin of those bituminous bodies which are found among the strata of the earth. in the case of stony substances, i have shown how unfounded all their theories are for the production of those concretions, crystallizations, and consolidated bodies. i am here to examine the subject of inflammable and combustible bodies, which i believe have been little considered by those theorists who suppose mineral bodies consolidated by infiltration. it is here that we shall find an infinite difference between the aqueous and igneous theories; for, we shall find it impossible to explain by the one certain operations which must have necessarily required the great agent generally employed in the other. the subject of this chapter is a touch-stone for every theory of the earth. in every quarter of this globe, perhaps in every extensive country, bituminous strata are to be found; they are alternated with those which are called aquiform, or which had been evidently formed by subsidence of certain moved materials at the bottom of the sea; so far, therefore, all those strata have had the same origin. in this point i think i may assert, that all the different theories at present are agreed; and it is only concerning certain transformations of those strata, since their original collection, that have been ascribed to different causes. of these transformations, which the strata must have undergone, there are two kinds; one in relation to change of place and position; the other in relation to solidity or consistence. it is only the last of those two changes which is here to be the subject of consideration; because, with regard to the first, there is nothing peculiar in these bituminous strata to throw any light, in that respect, upon the others. this is not the case with regard to the transformation in their chemical character and consistence; bituminous bodies may not be affected by chemical agents, such as fire and water, in the same manner as the argillaceous, siliceous, micaceous, and such other strata that are alternated with the bituminous; and thus we may find the means for investigating the nature of that agent by which those strata in general have been transformed in their substance; or we may find means for the detecting of false theories which may have been formed with regard to those operations in which the original deposits of water had been changed. we have had but two theories, with regard to the transformation of those bodies which have had a known origin, or to the change of their substance and consistence; the one of these which i have given is that of heat or fusion; the other, which i wish to be compared with mine, is that of water and infiltration. it is by this last that all authors hitherto, in one shape or another, have endeavoured to explain the changes that those strata must have undergone since the time of their first formation at the bottom of the sea. they indiscriminately apply the doctrine of infiltration to those strata of mineral coal as to any other; they say that bituminous matter is infiltrated with the water, impregnates certain strata of earth with bituminous matter, and thus converts them into mineral coal, and bituminous strata. this is not reasoning physically, or by the inductive method of proceeding upon matter of fact; it is reasoning fantastically, or by making gratuitous supposition founded merely on imagination. it was thus that natural philosophers reasoned before the age of science; the wonder now is, how men of science, in the present enlightened age, should suffer such language of ignorance and credulity to pass uncensured. the subject which i am now to treat of consists of peculiar strata of the earth, bodies which we may investigate through all the stages of their change, which is extreme; for, from vegetable bodies produced upon the habitable earth, they are now become a mineral body, and the most perfect coal,--a thing extremely different from what it had been, and a thing which cannot be supposed to have been accomplished by the operation of water alone, or any other agent in nature with which we are acquainted, except the action of fire or heat. it is therefore impossible for a philosopher, reasoning upon actual physical principles, not to acknowledge in this a complete proof of the theory which has been given, and a complete refutation of that aqueous operation which has been so inconsiderately supposed as consolidating the strata of the earth, and forming the various mineral concretions which are found in that great body. to see this, it will be sufficient to trace the progress of vegetable and animal substances, (bodies which had certainly lived by means of a former earth), to this changed state in which they have become perfect mineral bodies, and constitute a part of the present earth. for, as these changes are perfectly explained by the one theory, and absolutely inconsistent with the other, there arises from this a conviction that must be irresistible to a person who can give proper attention to a chain of reasoning from effect to cause. but if we thus succeed to illustrate the theory of the earth by the natural history of those particular strata, we have but one step farther to make in order to bring all the other parts of the earth, whether stratified or not, into the most perfect consistence with the theory; now this step, it will be most easy to make; and i shall now mention it, that so the reader may keep it in his view: pyrites is a sulphureo-metallic substance, which cannot be produced by means of water, a substance which the influences of the atmosphere decomposes or separates into its elements, and which even our imperfect art may be considered as able to produce, by means of fusion in our fires. therefore, the finding of this creature of fire intimately connected with those consolidated strata of mineral coal, adds the greatest confirmation, were it necessary, to the doctrine of those mineral bodies having been consolidated by fusion. this confirmation, however, is not necessary, and it is not the only thing which i am at present to illustrate in that doctrine. what i have now in view is, to homologate the origin of those coal strata, with the production of every other mineral substance, by heat or fusion; and this is what the intimate connection of pyrites with those strata will certainly accomplish. this will be done in the following manner: pyrites is not only found in great masses along with the coal strata; it is contained in the veins which traverse those strata, and in the minute ramifications of those veins, which are occasioned by the contraction of the mass, and generally divide it into small cubical pieces; but besides that extrinsic connection, (as it may be called,) with the stratum of coal, pyrites is found intimately connected with that solid body, in being mixed with its substance. if, therefore, it were proved, that either the one or other of those two substances had been consolidated by fusion, the other must be acknowledged as having had the same origin; but now i am to prove, from the natural history of mineral coal, that pyrites had been there formed by fusion; and then, by means of the known origin of that sulphureo-metallic substance, we shall extend our knowledge to the origin of every other mineral body. the process of this argument is as follows: every mineral body, i believe, without exception, will be found so intimately connected with pyrites, that these two things must be concluded as having been together in a fluid state, and that, whatever may have been the cause of fluidity in the one, this must have also caused the fluidity in the other; consequently, whatever shall be proved with regard to the mineral operations of pyrites, must be considered as proved of every other mineral substance. but, from the connection of pyrites with mineral coal, it is to be proved that the origin of this metallic body had been fusion; and then it will appear, that all other mineral bodies must have been more or less in fusion, or that they must have been consolidated by means of heat, and not by any manner of solution or aqueous infiltration. i therefore now proceed to take a view of the natural history of coal strata,--a subject which mineralogists seem not inclined to engage with, although the most ample data are to be found for that investigation. sect. ii.--natural history of coal strata, and theory of this geological operation. fossil coal is the species of stratum best understood with regard to its accidents, as being much sought after; at least, this is the case in many parts of britain, where it supplies the place of wood for burning. this fossil body has the most distinguished character; for, being inflammable or combustible in its nature, there is no other species of stratum that may be confounded with it. but, though coal be thus the most distinguishable mineral, and that which is best understood in the science of mining, it is perhaps the most difficult to be treated of in the science of mineralogy; for, not having properly any distinguishable parts, we have nothing in the natural constitution of this body, as we have in most other strata, to lead us to the knowledge of its original state or first formation. the varieties of coal are distinguished by their different manner of burning; but, from appearances of this kind, no perfect judgement can be formed with regard to the specific manner in which those strata had been made; although, from chemical principles, some conclusion may be drawn concerning certain changes which they have undergone since they had been formed. thus we have one species of coal which is extremely fusible, abounds with oil, and consequently is inflammable; we have another species again which is perfectly fixed and infusible in the fire; therefore, we may conclude upon principle, that, however, both those coals must have undergone the operation of heat and fusion, in bringing them to their present state, it is only the last that has become so much evaporated as to become perfectly fixed, or so perfectly distilled, as to have been reduced to a caput mortuum. the argument here employed is founded upon this fact; that, from the fusible species of coal, a caput mortuum may be formed by distillation, and that this chemical production has every essential quality, or every peculiar property, of the fixed and infusible species; although, from the circumstances of our operation, this caput mortuum may not have precisely the exterior appearance of the natural coal. but, we have reason to believe, it is not in the nature of things to change the infusible species, so as to make it fusible or oily. now, that this body was not formed originally in its present state, must appear from this, that the stratum here considered is perfectly solid; but, without fusion, this could not have been attained; and the coal is now supposed to be infusible. consequently, this fixed substance, which is now, properly speaking, a perfect coal, had been originally an oily bituminous or fusible substance. it is now a fixed substance, and an infusible coal; therefore, it must have been by means of heat and distillation that it had been changed, from the original state in which this stratum had been formed. we have thus, in the examination of coal strata upon chemical principles, received a certain lesson in geology, although this does not form a proper distinction by which to specify those strata in general, or explain the variety of that mineral. for, in this manner, we could only distinguish properly two species of those strata; the one bituminous or inflammable; the other proper coal, burning without smoke or flame. thus it will appear that, as this quality of being perfectly charred is not originally in the constitution of the stratum, but an accident to which some strata of every species may have been subjected, we could not class them by this property without confounding together strata which had differences in their composition or formation. therefore, we are led to inquire after some other distinction, which may be general to strata of fossil coal, independent of those changes which this substance may have undergone after it had been formed in a stratum. perfect mineral coal being a body of undistinguishable parts, it is only in its resolution that we may analyse it, and this is done by burning. thus, in analysing coal by burning, we have, in the ashes alone, that by which one species of coal may be distinguished from another; and, if we should consider pure coal as having no ashes of itself, we should then, in the weight of its ashes, have a measure of the purity of the coal, this being inversely as the quantity of the ashes. now, though this be not accurately true, as the purest coal must have some ashes proper to itself, yet, as this is a small matter compared with the quantity of earthy matter that may be left in burning some species of coal, this method of analysis may be considered as not far removed from the truth. but, in distinguishing fossil coal by this species of chemical analysis, not only is there to be found a perfect or indefinite gradation from a body which is perfectly combustible to one that is hardly combustible in any sensible degree, we should also fall into an inconveniency similar to that already mentioned, of confounding two things extremely different in their nature, a bituminous body, and a perfect charcoal. thus, if we shall found our distinction upon the fusibility and different degree of having been charred, we shall confound fossil coals of very different degrees of value in burning, or of very different compositions as strata; if, again, we found it upon the purity of composition, in judging from the ashes, we shall confound fossil bodies of very different qualities, the one burning with much smoke and flame, the other without any; the one fusible almost like wax, the other fixed and infusible as charcoal. it will now appear, that what cannot be done in either the one or other of those two methods, may in a great degree, or with considerable propriety, be performed in employing both. thus, whether for the economical purposes of life, or the natural history of fossil coal, those strata should be considered both with regard to the purity of their composition as inflammable matter deposited at the bottom of the sea, and to the changes which they have afterwards undergone by the operation of subterranean heat and distillation. we have now considered the original matter of which coal strata are composed to be of two kinds; the one pure bitumen or coal, as being perfectly inflammable or combustible; the other an earthy matter, with which proper coal may be variously mixed in its composition, or intimately connected, in subsiding from that suspended state by which it had been carried in the ocean. it is a matter of great importance, in the physiology of this globe, to know that the proper substance of coal may be thus mixed with heterogeneous bodies; for, supposing that this earthy matter, which has subsided in the water along with coal, be no farther connected with the combustible substance of those strata, than that it had floated in the waters of the ocean, and subsided _pari passu_ with the proper materials of the coal, we hence learn a great deal with regard to the state in which the inflammable matter must have been at the time of its formation into strata. this will appear by considering, that we find schistus mixed with coal in the most equal or uniform manner, and in almost every conceivable degree, from the purest coal to the most perfect schistus. hence we have reason to conclude, that, at the formation of those strata, the bituminous matter, highly subtilised, had been uniformly mixed with the earth subsiding in the water. not only is the bituminous matter of coal found mixed in every different proportion with the earthy or uninflammable materials of strata, but the coaly or bituminous composition is found with perhaps every different species of substance belonging to strata. this is certain, that we have the coaly matter intimately mixed with argillaceous and with calcareous strata. thus it will appear, that it is no proper explanation of the formation of coal strata, to say that vegetable matter is the basis of those strata; for though, in vegetation, a substance proper for the formation of bituminous matter is produced, it remains to know by what means, from a vegetable body, this bituminous matter is produced, and how it comes to be diffused in that subtile state by which it may be uniformly mixed with the most impalpable earth in water. could we once resolve this question, every other appearance might be easily explained. let us therefore now endeavour to discover a principle for the resolving of this problem. there are two ways in which vegetable bodies may be, in part at least, resolved into that subtilised state of bituminous matter after which we inquire; the one of these is by means of fire, the other by water. we shall now consider these severally as the means of forming bituminous strata, although they may be both employed by nature in this work. when vegetable bodies are made to burn, there is always more or less of a fuliginous substance formed; but this fuliginous substance is no other than a bituminous body in that subtilised state in which it is indefinitely divided, and may be mixed uniformly with any mass of matter equally subtilised with itself. but this is precisely what we want, in order to compose the strata of coal in question. if, therefore, there were to be found in the ocean such a fund of this fuliginous substance as might suffice for the formation of bituminous strata, no difficulty would be left in explaining the original of fossil coal. but tho' sufficient quantity of this fuliginous matter might not be found for the explanation of natural appearances, yet there cannot be a doubt that more or less of this matter must be produced in the mineral operations of the globe, and be found precisely in that place where it is required for the forming of those strata of coal. in order to conceive this, we are to consider, that there are actually great quantities of coal strata in a charred state, which indicates that all their more volatile oleaginous or fuliginous matter had been separated by force of subterranean heat; and, we are to suppose that this had been transacted at the bottom of the ocean: consequently, a subtile oleaginous, bituminous, or fuliginous substance, must have been diffused in that ocean; and this bituminous matter would be employed in forming other strata, which were then deposited at the bottom of the waters. but besides this quantity of bituminous matter which is necessarily formed in the mineral operations of the earth, and with regard to the quantity of which we can never form a proper estimate, there must enter into this same calculation all the fuliginous matter that is formed in burning bodies upon the surface of this earth. this bituminous matter of smoke is first delivered into the atmosphere, but ultimately it must be settled at the bottom of the sea. hence though, compared with the quantity that we think required, each revolution of the globe produces but a little in our estimation, yet the progress of time, in reforming worlds, may produce all that is necessary in the formation of our strata. there now remains to explain the other way in which bituminous matter may be obtained from vegetable bodies, that is, by means of water. for this purpose we must begin with a part of natural history that will throw some light upon the subject. all the rivers in scotland run into the sea tinged with a brown substance; this is most evident in some of them after a flood, and while yet the river is swelled; but, in travelling to the north of scotland in the summer season, without any rain, i saw all the rivers, without exception, of a brown colour, compared with a river of more clear water. this colour proceeds from the moss water, as it is called, which runs into the rivers, or the infusion of that vegetable substance which forms combustible turf, called peat. now, this moss water leaves, upon evaporation, a bituminous substance, which very much resembles fossil coal. therefore, in order to employ this vegetable infusion, delivered into the ocean for the purpose of forming bituminous strata at its bottom, it is only required to make this bituminous matter separate and subside. if now we consider the immense quantity of inflammable vegetable substance, dissolved in water, that is carried into the sea by all the rivers of the earth, and the indefinite space of time during which those rivers have been pouring in that oily matter into the sea; and if we consider, that the continual action of the sun and atmosphere upon this oily substance tends, by inspissation, to make it more and more dense or bituminous, we cannot hesitate in supposing a continual separation of this bituminous matter or inspissated oil from the water, and a precipitation of it to the bottom of the sea. this argument is corroborated by considering, that, if it were otherwise, the water of the sea must have, during the immense time that rivers are proved to have run, be strongly impregnated with that oily or bituminous substance; but this does not appear; therefore we are to conclude, that there must be the means of separating that substance from the water in which it had been dissolved. if there is thus, from the continual perishing of animal and vegetable bodies upon the surface of this earth and in the sea, a certain supply of oily or bituminous matter given to the ocean, then, however small a portion of this shall be supposed the whole oily or inflammable matter produced upon the surface of the earth, or however long time it may require for thus producing a stratum or considerable body of coal, we must still see in this a source of the materials proper for the production of that species of strata in the bottom of the sea. we have now considered the proper materials of which pure fossil coal is chiefly formed; we have at present to consider what should be the appearances of such a substance as this collected at the bottom of the sea, and condensed or consolidated by compression and by heat. we should thus have a body of a most uniform structure, black, breaking with a polished surface, and more or less fusible in the fire, or burning with more or less smoke and flame, in proportion as it should be distilled or inspissated, less or more, by subterranean heat. but this is the description of our purest fossil coals, which burn in giving the greatest quantity of heat, and leave the smallest quantity of ashes. in order to form another regular species of coal, let us suppose that, along with the bituminous substance now considered, there shall be floating in the water of the ocean a subtile earthy substance, and that these two different substances shall subside together in an uniform manner, to produce a stratum which shall be covered with immense weight, compressed, condensed, and consolidated as before, we should thus have produced a most homogeneous or uniform body to appearance, but not so in reality. the mixture of heterogeneous matter, in this case, is too minute to be discovered simply by inspection; it must require deep reflection upon the subject, with the help of chemical analysis, to understand the constitution of this body, and judge of all the circumstances or particulars in which it differs from the former. it is worth while to examine this subject with some attention, as it will give the most instructive view of the composition of bituminous strata, both those which are not considered as coal, and also the different species of that mineral body. in the first place then, if the mixture of those two different substances had been sufficiently perfect, and the precipitation uniform, the solid body of coal resulting from this mixture, would not only appear homogeneous, but might break equally or regularly in all directions; but the fracture of this coal must visibly differ from the former, so far as the fracture of this heterogeneous coal cannot have the polished surface of the pure bituminous body; for, the earthy matter that is interposed among the bituminous particles must affect the fracture in preventing its surface from being perfectly smooth. this imperfect plane of the fracture may be improved by polishing; in which case the body might be sufficiently smooth to have an agreeable polish; but it cannot have a perfect polish like a homogeneous body, or appear with that glassy surface which is naturally in the fracture of the pure bituminous coal. but this is also a perfect description of that species of coal which is called in england kennel coal, and in scotland parrot coal. it is so uniform in its substance that it is capable of being formed on the turning loom; and it receives a certain degree of polish, resembling bodies of jet. thus, we have a species of coal in which we shall find but a small degree of fusibility, although it may not be charred in any degree. such an infusible coal may therefore contain a great deal of aqueous substance, and volatile oily matter; consequently may burn with smoke and flame. but this same species of coal may also occasionally be charred more or less by the operation of subterranean heat; and, in that case, we should have a variety of coal which could only be distinguished, from a similar state of pure bituminous coal, by the ashes which they leave in burning. at least, this must be the case, when both species are, by sufficient distillation, reduced to the state of what may be properly termed a chemical coal. but in the natural state of its composition, we find those strata of kennel or parrot coal, possessing a peculiar property, which deserves to be considered, as still throwing more light upon the subject. we have been representing these strata of coal as homogeneous to appearance, and as breaking indifferently in all directions; this last, perhaps, is not so accurate; for they would seem to break chiefly into two directions, that is, either parallel or perpendicular to the bed. thus we have this coal commonly in rectangular pieces, in which it is extremely difficult to distinguish the direction of the bed, or stratification of the mass. by an expert eye, however, this may be in general, or at least sometimes, distinguished, and then, by knowing the habit of the coal in burning, a person perfectly ignorant of the philosophy of the matter may exhibit a wonderful sagacity, or even of power over future events, in applying this body to fire; for, at his pleasure, and unknown to those who are not in the secret; he may apparently, in equal circumstances, make this coal either kindle quietly, or with violent cracking and explosions, throwing its splinters at a distance. the explanation lies in this, that, though the rectangular mass of coal appears extremely uniform in its structure, it is truly a stratified mass; it is therefore affected, by the sudden approach of fire in a very different manner, according as the edge of the stratum, which is seen in four of the sides of this supposed cube, shall be applied to the fire, or the other two sides, which are in the line of the stratum, or parallel to the bed of coal. the reason of this phenomenon now remains to be considered. when the edge of the coal is exposed to the fire, the stratification of the coal is opened gradually by the heat and expanding vapours, as a piece of wood, of a similar shape, would be by means of wedges placed in the end way of the timber. the coal then kindles quietly, and quickly flames, while the mass of this bituminous schistus is opening like the leaves of a book, and thus exhibits an appearance in burning extremely like wood. but let the fire be applied to the middle of the bed, instead of the edge of the leaves, and we shall see a very different appearance; for here the expanded aqueous vapours, confined between the _laminae_, form explosions, in throwing off splinters from the kindling mass; and this mass of coal takes fire with much noise and disturbance. the ashes of this coal may be determined as to quality, being in general a subtile white earth; but, as to quantity, the measure of that earth produces an indefinite variety in this species of coal; for, from the kennel or parrot coal, which is valuable for its burning with much flame, to that black schistus which our masons use in drawing upon stone, and which, though combustible in some degree, is not thought to be a coal, there is a perfect gradation, in which coal may be found with every proportion of this earthy alloy. among the lowest species of this combustible schistus are those argillaceous strata in yorkshire from whence they procure alum in burning great heaps of this stone, which also contains sulphur, to impregnate the aluminous earth with its acid. we have also, in this country, strata which differ from those aluminous schisti only in the nature of the earth, with which the bituminous sediment is mixed. in the strata now considered, the earth, precipitated with the bituminous matter, being calcareous, has produced a limestone, which, after burning especially, is perfectly fissile. therefore, with regard to the composition of mineral coal, the theory is this. that inflammable, vegetable, and animal substances, in a subtilised state, had subsided in the sea, being mixed more or less with argillaceous, calcareous, and other earthy substances in an impalpable state. now, the chemical analysis of fossil coal justifies that theory; for, in the distillation of the inflammable or oily coal, we procure volatile alkali, as might be naturally expected. thus we have considered fossil coal as various, both in its state and composition; we have described coal which is of the purest composition, as well as that which is most impure or earthy; and we have shown that there is a gradation, from the most bituminous state in which those strata had been formed in being deposited at the bottom of the sea, to the most perfect state of a chemical coal, to which they have been brought by the operation of subterranean fire or heat. we have been hitherto considering fossil coal as formed of the impalpable parts of inflammable bodies, united together by pressure, and made to approach in various degrees to the nature of a chemical coal, by means of subterranean heat; because, from the examination of those strata, many of them have evidently been formed in this manner. but vegetable bodies macerated in water, and then consolidated by compression, form a substance of the same kind, almost undistinguishable from some species of fossil coal. we have an example of this in our turf pits or peat mosses; when this vegetable substance has been compressed under a great load of earth, which sometimes happens, it is much consolidated, and hardens, by drying, into a black body, not afterwards dilutable or penetrated by water, and almost undistinguishable in burning from mineralised bodies of the same kind. also, when fossil wood has been condensed by compression and changed by the operation of heat, as it is frequently found in argillaceous strata, particularly in the aluminous rock upon the coast of yorkshire, it becomes a jet almost undistinguishable from some species of fossil coal. there cannot therefore be a doubt, that if this vegetable substance, which is formed by the collection of wood and plants in water upon the surface of the earth, were to be found in the place of fossil coal, and to undergo the mineral operations of the globe, it must at least augment the quantity of those strata, though it should not form distinct strata by itself. it may perhaps be thought that vegetable bodies and their impalpable parts are things too far distant in the scale of magnitude to be supposed as subsiding together in the ocean; and this would certainly be a just observation with regard to any other species of bodies: but the nature of vegetable bodies is to be floatant in water; so that we may suppose them carried at any distance from the shore; consequently, the size of the body here makes no difference with regard to the place or order in which these are to be deposited. the examination of fossil coal fully confirms those reasonable suppositions. for, _first_, the strata that attend coal, whether the sandstone or the argillaceous strata, commonly, almost universally, abound with the most distinct evidence of vegetable substances; this is the impressions of plants which are found in their composition. _secondly_, there is much fossil coal, particularly that termed in england clod coal, and employed in the iron foundry, that shows abundance of vegetable bodies in its composition. the strata of this coal have many horizontal interstices, at which the more solid shining coal is easily separated; here the fibrous structure of the compressed vegetable bodies is extremely visible; and thus no manner of doubt remains, that at least a part of this coal had been composed of the vegetable bodies themselves, whatever may have been the origin of the more compact parts where nothing is to be distinguished. the state in which we often find fossil wood in strata gives reason to conclude that this body of vegetable production, in its condensed state, is in appearance undistinguishable from fossil coal, and may be also in great quantity; as, for example, the bovey coal in devonshire. thus the strata of fossil coal would appear to be formed by the subsidence of inflammable matter of every species at the bottom of the sea, in places distant from the shore, or where there had been much repose, and where the lightest and most floatant bodies have been deposited together. this is confirmed in examining those bodies of fossil coal; for, though there are often found beds of sand-stone immediately above and below the stratum of the coal, we do not find any sand mixed in the strata of the coal itself. having found the composition of coal to be various, but all included within certain rules which have been investigated, we may perceive in this an explanation of that diversity which is often observed among the various strata of one bed of coal. even the most opposite species of composition may be found in the thickness of one bed, although of very little depth, that is to say, the purest bituminous coal may, in the same bed, be conjoined with that which is most earthy. fossil coal is commonly alternated with regular sand-stone and argillaceous strata; but these are very different bodies; therefore, it may perhaps be inquired how such different substances came to be deposited in the same place of the ocean. the answer to this is easy; we do not pretend to trace things from their original to the place in which they had been ultimately deposited at the bottom of the sea. it is enough that we find the substance of which we treat delivered into the sea, and regularly deposited at the bottom, after having been transported by the currents of the ocean. now the currents of the ocean, however regular they may be for a certain period of time, and however long this period may be protracted, naturally change; and then the currents, which had given birth to one species of stratum in one place, will carry it to another; and the sediment which the moment before had formed a coal stratum, or a bed of that bituminous matter, may be succeeded either with the sediment of an argillaceous stratum, or covered over with a bed of sand, brought by the changed current of the sea. we have now considered all the appearances of coal strata, so far as these depend upon the materials, and their original collection. but, as those bituminous strata have been changed in their substance by the operation of subterranean heat and inspissation, we are now to look for the necessary consequences of this change in the body of the stratum; and also for other mineral operations common to fossil coal with consolidated strata of whatever species. if coal, like other mineral strata, have been inspissated and consolidated by subterranean heat, we should find them traversed with veins and fissures; and, if the matter found in those veins and fissures corresponds to that found in similar places of other strata, every confirmation will be hence given to the theory that can be expected from the consideration of those bituminous strata. but this is the case; we find those fissures filled both with calcareous, gypseous, and pyritous substances. therefore, we have reason to conclude, that the strata of fossil coal, like every other indurated or consolidated body in the earth, has been produced, _first_, by means of water preparing and collecting materials proper for the construction of land; and, _secondly_, by the operation of internal fire or subterranean heat melting and thus consolidating every known substance of the globe. not only are those sparry and pyritous substances, which are more natural to coal strata, found forming veins traversing those strata in various directions, but also every other mineral vein may occasionally be found pervading coal mines, or traversing bituminous strata. gold, silver, copper, lead, calamine, have all, in this manner, been found in coal. there remains now only to consider those bituminous strata of fossil coal in relation to that change of situation which has happened more or less to every stratum which we examine; but which is so much better known in those of coal, by having, from their great utility in the arts of life, become a subject for mining, and thus been traced in the earth at great expense, and for a long extent. coal strata, which had been originally in a horizontal position, are now found sometimes standing in an erect posture, even almost perpendicular to the plane in which they had been formed. miners therefore distinguish coal strata according as they deem them to approach to the one or other of those two extremes, in terming them either flat or edge seams or veins. thus, it will appear, that every possible change from the original position of those strata may have happened, and are daily found from our experience in those mines. but besides the changed position of those strata, in departing from the horizontal line or flat position in which they had been formed, there is another remarkable change, termed by miners a _trouble_ in the coal. the consideration of this change will further illustrate the operations of nature in placing that which had been at the bottom of the sea above its surface. strata, that are in one place regularly inclined, may be found bended, or irregularly inclined, in following their course. here then is a source of irregularity which often materially effects the estimates of miners, judging from what they see, of those parts which are to be explored; and this is an accident which they frequently experience. but, without any change in the general direction of the stratum, miners often find their coal broke off abruptly, those two parts being placed upon a higher and lower situation in respect to each other, if flat beds, or separated laterally if they are edge seams. this is by miners termed a _slip, hitch_, or _dyke_. these irregularities may either be attended with an injected body of subterraneous lava or basaltes, here termed whin-stone, or they may not be attended, at least apparently, _i.e._ immediately, with any such accident. but experienced miners know, that, in approaching to any of those injected masses of stone, which are so frequent in this country, their coal is more and more subject to be troubled. as there is, in this country of scotland, two different species of mountains or hills, one composed both in matter and manner exactly similar to the alps of switzerland, the other of whin-stone, basaltic rock, or subterraneous lava; and as the fossil coal, argillaceous and sand-stone strata, are found variously connected with those hills, nothing can tend more to give a proper understanding, with regard to the construction of the land in general, of the globe than a view of those different bodies, which are here found much mixed together in a little space of country, thus exhibiting, as it were in miniature, what may be found in other parts of the world, upon a larger scale, but not upon any other principle. i will therefore endeavour to give a short description of the mineral state of this country with regard to coal, so far as my experience and memory will serve. this country might very properly be considered as consisting of primary and secondary mountains; not as supposing the primary mountains original and inexplicable in their formation, any more than those of the latest production, but as considering the one to be later in point of time, or posterior in the progress of things. the first are those which commonly form the alpine countries, consisting of various schisti, of quartzy stone, and granites. the second, again, are the whinstone or basaltic hills scattered up and down the low country, and evidently posterior to the strata of that country, which they break, elevate, and displace. thus there are in this country, as well as every where else, three things to be distinguished; first, the alpine or elevated country; secondly, the flat or low country; and, thirdly, that which has been of posterior formation to the strata which it traverses, in whatever shape or quality; whether as a mountain, or only as a vein; whether as a basaltes, a porphyry, or a granite, or only as a metal, a siliceous substance, or a spar. those three things which are here distinguished do not differ with regard to the chemical character of their substances; for, in each of these, every different substance is to be found, more or less; and it is not in being composed of materials peculiar to itself, that makes an alpine country be distinguished from a flat country; it is chiefly in the changes which the strata of the alpine country have been made to undergo, posterior to their original collection, that the rocks of the alpine country differ from those of the flat country. but the observation that is most to the purpose of the present subject of bituminous strata, is this; it is chiefly in the strata of the flat country that fossil coal are found; there are none that i know of in all the alpine countries of scotland; and it is always among the strata peculiar to the flat country that fossil coal is found. now, this appearance cannot be explained by saying that the materials of mineral coal had not existed in the world while those primary strata were formed in the sea. i have already shown, (chap. .) that there had been the same system of a world, producing plants, and thus maintaining animals, while the primary strata were formed in the sea; i have even adduced an example of coal strata among those primary schisti, although this be an extremely rare occurrence: consequently, we are under the necessity of looking out for some other cause. if the changes which have been evidently superinduced in the strata of alpine countries arise from the repeated operations of subterranean fire, or to the extreme degree in which those strata have been affected by this consolidating and elevating cause, it will be natural to suppose that the bituminous or combustible part among those stratifications, may have been mostly consumed upon some occasion during those various and long continued operations; whereas, in the flat beds of the low country, although there is the most perfect evidence for the exertion of heat in the consolidation of those strata, the general quantity of this has been a little thing, compared with the universal manifestation of this cause in the operations of the alpine countries, the strata of which have been so much displaced in their situations and positions. to illustrate this, strata of sand-stone are found in both the alpine and flat countries of scotland. about leadhills, for example, there are abundance of those strata; but, in the flat country, the generality of the sand-stone is so little changed as to appear to every enlightened naturalist aquiform strata; whereas the most enlightened of those philosophers will not perhaps attribute the same original to a similar composition in the alpine country, which is so much changed from its original state. it is not because there had been wanting a sufficient degree of heat to consolidate the sand-stone in the coal country; for i can show specimens of sand-stone almost contiguous with coal, that have been extremely much consolidated in this manner. but this is only a particular stratum; and the general appearance of the sand-stone, as well as other strata in the coal countries, is that of having been little affected by those subterranean operations of heat by which those bodies in the alpine country have been changed in their structure, shape, and position. if we shall thus allow the principle of consolidation, consequently also of induration, to have been much exerted upon the strata of the alpine country, and but moderately or little upon those of the low country of scotland, we shall evidently see one reason, perhaps the only one, for the lesser elevation of the one country above the level of the sea, than the other. this is because the one resists the powers which have been employed in leveling what has been raised from the bottom of the sea, more than the other; consequently, we find more of the one remaining above the level of the sea than of the other. let us now take the map of scotland, in order to observe the mixture of those two different species of countries, whereof the one is generally low and flat, the other high and mountainous; the one more or less provided with fossil coal, the other not. from st abb's head, on the east of scotland, to the mull of galloway, on the west, there runs a ridge of mountains of granite, quartz, and schistus strata, which contain not coal. on each side of this ridge we find coal countries; northumberland, on the one side, and, on the other, the shires of ayr, lanark, and the lothians; the one is a mountainous country, the others are comparatively low or flat countries. let us now draw another alpine line from buchan and caithness, upon the east, to the island of jura, on the west; this traverses a mountainous country destitute of coal, and, so far as i know, of any marks of marine bodies. but, on each side of this great alpine ridge, we find the hard country skirted with one which is lower, flatter, or of a softer nature, in which coal is found, upon the one side, in the shires of fife, clackmannan, and stirling; and, on the other, in that hollow which runs from the murray frith south-west, in a straight line, directed upon the end of mull, and composed, for the most part, of water very little above the level of the sea. here, to be sure, the coal is scarce, or not so evident; but there is coal upon the sea coast in several places of this great bay betwixt buchan and caithness; and the lowness of the country, across this part of the island, is almost sufficient testimony that it had been composed of softer materials. thus the coal country of scotland may be considered as in one band across the island, and included in the counties of ayr, lanark, and all those which border upon the frith of forth. now, in all this tract of coal and tender strata, we do not find ridges of alpine stone or primary mountains, but we find many hills of solid rock, little mountains, from to feet high; such as that beautiful conical hill north berwick law, torpender law, arthur's seat, the lowmands, and others of inferior note. that is to say, the whole of this included space, both sea and land, has been invaded from below with melted masses of whin-stone, breaking up through the natural strata of the country, and variously embossing the surface of the earth at present, when all the softer materials, with which those subterranean lavas had been covered, are washed away or removed from those summits of the country. hence there is scarcely a considerable tubercle, with which this country also abounds, that may not be found containing a mass of whin-stone as a nucleus. but besides those insulated masses of whinstone that form a gradation from a mountain to a single rock, such, for example, as that on which the castle of edinburgh is built, we find immense quantities of the same basaltic rock interjected among the natural strata, always breaking and disordering them, but often apparently following their directions for a considerable space with some regularity. we also find dykes of the same substance bisecting the strata like perpendicular veins of rock; and, in some places, we see the connection of these rocks of the same substance, which thus appear to be placed in such a different form in relation to the strata. it will thus appear, that the regular form, and horizontal direction of strata throughout this country of coal, now under contemplation, has been broken and disordered by the eruption and interjection of those masses of basaltic stone or subterraneous lava; and thus may be explained not only the disorders and irregularities of coal strata, but also the different qualities of this bituminous substance from its more natural state to that of a perfect coal or fixed infusible and combustible substance burning without smoke. this happens sometimes to a part of a coal stratum which approaches the whin-stone. having thus stated the case of combustible or bituminous strata, i would ask those naturalists, who adhere to the theory of infiltration and the operation of water alone, how they are to conceive those strata formed and consolidated. they must consider, that here are immense bodies of those combustible strata, under hundreds, perhaps thousands, of fathoms of sand-stone, iron-stone, argillaceous and calcareous strata. if they are to suppose bituminous bodies collected at the bottom of the sea, they must say from whence that bitumen had come; for, with regard to the strata below those bituminous bodies, above them, and between them, we see perfectly from whence had come the materials of which they are formed. they cannot say that it is from a collection of earthy matter which had been afterwards bituminized by infiltration; for, although we find many of those earthy strata variously impregnated with the bituminous and coaly matter, i have shown that the earthy and the bituminous matter had subsided together; besides, there are many of those coaly and bituminous strata in which there is no more than two or three _per cent._ of earthy matter or ashes after burning; therefore the strata must have been formed of bituminous matter, and not simply impregnated with it. to avoid this difficulty, we shall allow them to form their strata, which certainly is the case in great part, by the collection of vegetable bodies; then, i desire them to say, in what manner they are to consolidate those bodies. if they shall allege that it is by simple pressure, how shall we conceive the numerous veins of spar and pyrites, which traverse those strata in all directions, to be formed in those bodies consolidated by the compression of the superincumbent masses?--here is a manifest inconsistency, which proves that it could not be. but, even were we to suppose all those difficulties to be over come, there is still an impossibility in the way of that inconsiderate theory, and this will appear more fully in the following chapter. sect. iii.--the mineralogical operations of the earth illustrated from the theory of fossil coal. there is not perhaps a greater difference among the various qualities of bodies than that which may be observed to subsist between the burning of those two substances, that is, the inflammable bodies on the one hand, and those that are combustible on the other. i have treated of that distinction in dissertations upon subjects of natural philosophy, part d. where i have considered the different effects of those two kinds of bodies upon the incident light; and, in a dissertation upon the philosophy of fire, etc. i have distinguished those two kinds of substances in relation to their emitting, in burning, the fixed light which had constituted a part of those inflammable and combustible bodies. all animals and vegetable bodies contain both those different chemical substances united; and this phlogistic composition is an essential part in every animal and vegetable substance. there are to be found in those bodies particular substances, which abound more or less with one of those species of phlogistic matter, but never is the one species of those burning substances to be found naturally, in animal and vegetable bodies, without being associated with the other; and it is all that the chemical art can do to separate them in a great degree upon occasion. pure ardent spirit may perhaps be considered as containing the one, and the most perfect coal the other; the chemical principle of the one is proper carbonic matter; and of the other it is the hydrogeneous principle, or that of inflammable air. thus we so far understand the composition of animal and vegetable substances which burn or maintain our fires; we also understand the chemical analysis of those bodies, in separating the inflammable from the combustible substance, or the volatile from the fixed matter, the oil from what is the proper coal. it is by distillation or evaporation, the effect of heat, that this separatory operation is performed; and we know no other means by which this may be done. therefore, wherever we find peculiar effects of that separatory operation, we have a right to infer the proper cause. the subject, which we are to consider in this section, is not the composition of strata in those of mineral coal, but the transformation of those, which had been originally inflammable bodies, into bodies which are only combustible, an end which is to be attained by the separation of their volatile or inflammable substances. in the last section, i have shown of what materials the strata of mineral coal had been originally formed; these are substances containing abundance of inflammable oil or bitumen, as well as carbonic matter which is properly combustible; and this is confirmed by the generality of those strata, which, though perfectly consolidated by fusion, retain still their inflammable and fusible qualities. but now the object of investigation is that mineral operation by which some of those strata, or some parts of a fusible and inflammable stratum, have been so changed as to become infusible and only combustible. we have now examined those strata which may be considered as either proper mineral coal, or as only a bituminous schistus; we are now to class along with these another species of this kind of matter, which has had a similar origin, although it may assume a different character. according to the common observations of mankind, the eminent quality by which coal is to be distinguished, is the burning of that substance, or its capacity for making a fire. therefore, however similar in other respects, a substance which had not that eminent quality of coal could hardly be considered as being allied to it; far less could it be supposed, as being in every other respect the same. we are however to endeavour to show, that there are truly substances of this kind, substances which to common observation, having none of the properties of coal with respect to fire, consequently, no utility for the purpose of burning, might be considered as another species of mineral, while at the same time they are truly at bottom a composition very little different from those which we have considered as the most perfect coal. it must be recollected that we have distinguished coal in general as of two different species, one perfect or proper coal, containing no perceptible quantity of either oil or phlegm; the other as burning with smoke and flame, consequently containing both aqueous and oleaginous substances which it emits in distillation. it is the first of these which we are now to consider more particularly, in order to see the varieties which may be found in this species of mineral substance. when that bituminous fossil, which is the common coal of this country, is submitted to heat it is subject to melt more or less, and emits smoke which is composed of water and oil. if it be thus completely distilled, it becomes a perfect coal of a porous or spongy texture. such a substance as this is extremely rare among minerals; i have however found it. it is in the harbour of ayr, where a whinstone dyke traverses the coal strata, and includes some of that substance in the state of coals or cinder. i pointed this out many years ago to dr black; and lately i showed it to professor playfair. but the culm of south wales, the kilkenny coal of ireland, and the blind coal of scotland, notwithstanding that these are a perfect coal, or charred to a coal, have nothing of the porous construction of the specimen which i have just now mentioned; they are perfectly solid, and break with a smooth shining surface like those which emit smoke and flame. here is therefore a mineral operation in the preparation of those coals which we cannot imitate; and here is the clearest evidence of the operation of mineral fire or heat, although we are ignorant of the reason why some coal strata are charred, while others are not, and why, in some particular cases, the charred coal may be porous or spongy like our coals, while in general those blind coals (as they are called) are perfectly solid in their structure. but to what i would call more particularly the attention of mineral philosophers is this, that it is inconceivable to have this effect produced by means of water; we might as well say that heat were to be the cause of ice. the production of coal from vegetable bodies, in which that phlogistic substance is originally produced, or from animal bodies which have it from that source, is made by heat, and by no other means, so far as we know. but, even heat alone is not sufficient to effect that end, or make a perfect coal; the phlogistic body, which is naturally compound, consisting of both inflammable and combustible substances, must be separated chemically, and this must be the operation of heat under the proper circumstances for distillation or evaporation. here is the impossibility which in the last chapter i have alleged the aqueous theory has to struggle against; and here is one of the absolute proofs of the igneous theory. not only must the aqueous part of those natural phlogistic bodies be evaporated, in order to their becoming coal, but the oily parts must also, by a still increased degree of heat, be evaporated, or separated by distillation from the combustible part. here, therefore, is evidently the operation of heat, not simply that of fusion in contradiction to the fluidity of aqueous solution, but in opposition to any effect of water, as requiring the absence or separation of that aqueous substance. but those natural appearances go still farther to confirm our theory, which, upon all occasions, considers the compression upon the bodies that are submitted to the operation of heat, in the mineral regions, as having the greatest efficacy in modifying that operation. coal strata, which are in the neighbourhood of each other, being of those two opposite species, the one fusible and inflammable, the other infusible and combustible, afford the clearest proof of the efficacy of compression; for, it is evident, that the coal, which was once bituminous or fusible, cannot be charred without the distillation of that substance; therefore, prevent the distillation by compression and the charring operation cannot proceed, whatever should be the intensity of the heat; and then, fusion alone must be the effect upon the bituminous body. but now, as we have both those species of coal in the vicinity of each other, and even the same strata of coal part charred, while the rest is not, this natural appearance, so far from being a stumbling block, as it must be to the opposite theory, is most clearly explained by the partial escape of vapours from the mineral regions, and thus confirms the theory with regard to the efficacy of compression. it is owing to the solidity of those natural charred coals, and the want of oil, that they are so very difficult of kindling; but, when once kindled in sufficient quantity, they make a fire which is very durable. there are even some of them which, to common observation, seem to be altogether incombustible. i have of this kind a specimen from a stratum at stair, which shall be afterwards mentioned. m. struve, in the journal de physique for january , describes a mineral which he calls _plombagine charbonneuse ou hexaëdre_; and gives for reason, _parce qu'elle ressemble extrêmement au charbon de pierre schisteux, ou d'hexaëdre_. he says farther, "il est très commun, dans une roche qui forme un passage entre les granits et les brèches, qu'on n'a trouvée jusqu'a présent qu'on masses roulées dans le pays de vaud." he concludes his paper thus: "ce fossile singulier ne paroît pas appartenir à la suisse seule. j'ai dans ce moment devant les yeux une substance parfaitement semblable, si on excepte la couleur qui tient le milieu entre le gris de fer et le rouge modéré; elle vient du pays de gotha de la friedrischs-grube, proche d'umneau. on le regarde comme un eisenrahm uni à du charbon de pierre." the specimen which i have from stair upon the water of ayr, so far as i can understand, perfectly resembles this _plombagine_ of m. struve. it consumes very slowly in the fire, and deflagrates like plumbago with nitre. now this comes from a regular coal stratum; and what is more remarkable, in this stratum is contained a true plumbago, farther up the country, the earl of dumfries has also a mine containing plumbago along with other coal strata; and though the plumbago of these two mines have not all the softness and beauty of the mineral of the same species from cumberland, they are nevertheless perfect plumbago. i have a specimen of steatetical whinstone or basaltes from some part of cumberland, in which is contained many nodules of the most perfect and beautiful plumbago. it is dispersed through this stone in rounded masses of all sizes from a nut to a pin's head; and many of these are mixed with pyrites. there is therefore reason to believe that this plumbago had been in fusion. now, if we consider that every species of coal and every species of plumbago are equally, that is, perfectly combustible, and yield, in burning, the same volatile principles, differing only perhaps a little in the small quantity of fixed matter which remains, we shall be inclined to believe, that they have all the same origin in a vegetable substance; and that they are diversified by some very small composition of other matter. this being allowed, one thing is certain, that it is by the operation of mineral fire or heat that those combustible substances, however composed, have been brought to their present state of coal, although we are ignorant of the circumstances by which their differences and their peculiar chemical and mechanical qualities have been produced. let us resume in a few words. there is not perhaps one substance in the mineral kingdom by which the operation of subterraneous heat is, to common understanding, better exemplified than that of mineral coal. those strata are evidently a deposit of inflammable substances which all come originally from vegetable bodies. in this state of their formation, those coal strata must all be oleagenous or bituminous. in many of them, however, these volatile parts are found wanting; and, the stratum is found in the state of the most perfect coal or caput mortuum. there, is, i presume, no other means to be found by which this eminent effect could be produced, except by distillation; and, this distillation perhaps proceeded under the restraining force of an immense compression. to this theory it must not be objected, that all the strata of coal, which are found in the same place or neighbourhood, are not reduced to that caput mortuum or perfect coaly state. the change from a bituminous to a coaly substance can only take place in proportion as the distillation of the volatile parts is permitted. now this distillation must be permitted, if any passage can be procured from the inflammable body submitted to the operation of subterraneous heat; and, one stratum of coal may find vent for the passage of those vapours, through some crevice which is not open to another. in this way, doubtless, some of those bodies have been inspissated or reduced to a fixed coal, while others, at a little distance, have retained most of their volatile parts. we cannot doubt of this distilling operation in the mineral regions, when we consider that in most places of the earth we find the evident effects of such distillation of oily substances in the naphta and petroleum that are constantly emitted along with water in certain springs. these oily substances are no other than such as may be procured, in a similar manner, from the fusible or inflammable coal strata; we have therefore every proof of this mineral operation that the nature of things admit of. we have also sufficient evidence that those fusible and inflammable coals, which have not been distilled to a caput mortuum, had been subjected to the operation of subterraneous heat, because we find those fusible coals subject to be injected with pyrites, as well as the more perfect coal. if we now consider those various appearances of mineral bodies which are thus explained by the theory of mineral fire, or exertion of subterraneous heat, appearances which it is impossible to reconcile by any supposition of aqueous solution, or that unintelligible language of mineral infiltration which has of late prevailed, we shall be fully satisfied, that there is a uniform system in nature of providing a power in the mineral regions, for consolidating the loose materials deposited at the bottom of the sea, and for erecting those masses of mineralized substances into the place of land; we shall thus be led to admire the wisdom of nature, providing for the continuation of this living world, and employing those very means by which, in a more partial view of things, this beautiful structure of an inhabited earth seems to be necessarily going into destruction. end of volume first. transcribed by david price, email ccx @coventry.ac.uk town geology preface this little book, including the greater part of this preface, has shaped itself out of lectures given to the young men of the city of chester. but it does not deal, in its present form, with the geology of the neighbourhood of chester only. i have tried so to recast it, that any townsman, at least in the manufacturing districts of england and scotland, may learn from it to judge, roughly perhaps, but on the whole accurately, of the rocks and soils of his own neighbourhood. he will find, it is true, in these pages, little or nothing about those "old red sandstones," so interesting to a scotchman; and he will have to bear in mind, if he belong to the coal districts of scotland, that the "stones in the wall" there belong to much older rocks than those "new red sandstones" of which this book treats; and that the coal measures of scotland, with the volcanic rocks which have disturbed them, are often very different in appearance to the english coal measures. but he will soon learn to distinguish the relative age of rocks by the fossils found in them, which he can now, happily, study in many local museums; and he may be certain, for the rest, that all rocks and soils whatsoever which he may meet have been laid down by the agents, and according to the laws, which i have tried to set forth in this book; and these only require, for the learning of them, the exercise of his own observation and common sense. i have not tried to make this a handbook of geological facts. such a guide (and none better) the young man will find in sir charles lyell's "student's elements of geology." i have tried rather to teach the method of geology, than its facts; to furnish the student with a key to all geology, rough indeed and rudimentary, but sure and sound enough, i trust, to help him to unlock most geological problems which he may meet, in any quarter of the globe. but young men must remember always, that neither this book, nor all the books in the world, will make them geologists. no amount of book learning will make a man a scientific man; nothing but patient observation, and quiet and fair thought over what he has observed. he must go out for himself, see for himself, compare and judge for himself, in the field, the quarry, the cutting. he must study rocks, ores, fossils, in the nearest museum; and thus store his head, not with words, but with facts. he must verify--as far as he can--what he reads in books, by his own observation; and be slow to believe anything, even on the highest scientific authority, till he has either seen it, or something like enough to it to make it seem to him probable, or at least possible. so, and so only, will he become a scientific man, and a good geologist; and acquire that habit of mind by which alone he can judge fairly and wisely of facts of any kind whatsoever. i say--facts of any kind whatsoever. if any of my readers should be inclined to say to themselves: geology may be a very pleasant study, but i have no special fancy for it. i had rather learn something of botany, astronomy, chemistry, or what not--i shall answer: by all means. learn any branch of natural science you will. it matters little to me which you learn, provided you learn one at least. but bear in mind, and settle it in your hearts, that you will learn no branch of science soundly, so as to master it, and be able to make use of it, unless you acquire that habit and method of mind which i am trying to teach you in this book. i have tried to teach it you by geology, because geology is, perhaps, the simplest and the easiest of all physical sciences. it appeals more than any to mere common sense. it requires fewer difficult experiments, and expensive apparatus. it requires less previous knowledge of other sciences, whether pure or mixed; at least in its rudimentary stages. it is more free from long and puzzling greek and latin words. it is specially, the poor man's science. but if you do not like it, study something else. only study that as you must study geology; proceeding from the known to the unknown by observation and experiment. but here some of my readers may ask, as they have a perfect right to ask, why i wish young men to learn natural science at all? what good will the right understanding of geology, or of astronomy, or of chemistry, or of the plants or animals which they meet--what good, i say, will that do them? in the first place, they need, i presume, occupation after their hours of work. if any of them answer: "we do not want occupation, we want amusement. work is very dull, and we want something which will excite our fancy, imagination, sense of humour. we want poetry, fiction, even a good laugh or a game of play"--i shall most fully agree with them. there is often no better medicine for a hard-worked body and mind than a good laugh; and the man who can play most heartily when he has a chance of playing is generally the man who can work most heartily when he must work. but there is certainly nothing in the study of physical science to interfere with genial hilarity; though, indeed, some solemn persons have been wont to reprove the members of the british association, and specially that red lion club, where all the philosophers are expected to lash their tails and roar, of being somewhat too fond of mere and sheer fun, after the abstruse papers of the day are read and discussed. and as for harmless amusement, and still more for the free exercise of the fancy and the imagination, i know few studies to compare with natural history; with the search for the most beautiful and curious productions of nature amid her loveliest scenery, and in her freshest atmosphere. i have known again and again working men who in the midst of smoky cities have kept their bodies, their minds, and their hearts healthy and pure by going out into the country at odd hours, and making collections of fossils, plants, insects, birds, or some other objects of natural history; and i doubt not that such will be the case with some of my readers. another argument, and a very strong one, in favour of studying some branch of natural science just now is this--that without it you can hardly keep pace with the thought of the world around you. over and above the solid gain of a scientific habit of mind, of which i shall speak presently, the gain of mere facts, the increased knowledge of this planet on which we live, is very valuable just now; valuable certainly to all who do not wish their children and their younger brothers to know more about the universe than they do. natural science is now occupying a more and more important place in education. oxford, cambridge, the london university, the public schools, one after another, are taking up the subject in earnest; so are the middle-class schools; so i trust will all primary schools throughout the country; and i hope that my children, at least, if not i myself, will see the day, when ignorance of the primary laws and facts of science will be looked on as a defect, only second to ignorance of the primary laws of religion and morality. i speak strongly, but deliberately. it does seem to me strange, to use the mildest word, that people whose destiny it is to live, even for a few short years, on this planet which we call the earth, and who do not at all intend to live on it as hermits, shutting themselves up in cells, and looking on death as an escape and a deliverance, but intend to live as comfortably and wholesomely as they can, they and their children after them--it seems strange, i say, that such people should in general be so careless about the constitution of this same planet, and of the laws and facts on which depend, not merely their comfort and their wealth, but their health and their very lives, and the health and the lives of their children and descendants. i know some will say, at least to themselves: "what need for us to study science? there are plenty to do that already; and we shall be sure sooner or later to profit by their discoveries; and meanwhile it is not science which is needed to make mankind thrive, but simple common sense." i should reply, that to expect to profit by other men's discoveries when you do not pay for them--to let others labour in the hope of entering into their labours, is not a very noble or generous state of mind--comparable somewhat, i should say, to that of the fatting ox, who willingly allows the farmer to house him, till for him, feed him, provided only he himself may lounge in his stall, and eat, and not be thankful. there is one difference in the two cases, but only one-- that while the farmer can repay himself by eating the ox, the scientific man cannot repay himself by eating you; and so never gets paid, in most cases, at all. but as for mankind thriving by common sense: they have not thriven by common sense, because they have not used their common sense according to that regulated method which is called science. in no age, in no country, as yet, have the majority of mankind been guided, i will not say by the love of god, and by the fear of god, but even by sense and reason. not sense and reason, but nonsense and unreason, prejudice and fancy, greed and haste, have led them to such results as were to be expected--to superstitions, persecutions, wars, famines, pestilence, hereditary diseases, poverty, waste--waste incalculable, and now too often irremediable--waste of life, of labour, of capital, of raw material, of soil, of manure, of every bounty which god has bestowed on man, till, as in the eastern mediterranean, whole countries, some of the finest in the world, seem ruined for ever: and all because men will not learn nor obey those physical laws of the universe, which (whether we be conscious of them or not) are all around us, like walls of iron and of adamant--say rather, like some vast machine, ruthless though beneficent, among the wheels of which if we entangle ourselves in our rash ignorance, they will not stop to set us free, but crush us, as they have crushed whole nations and whole races ere now, to powder. very terrible, though very calm, is outraged nature. though the mills of god grind slowly, yet they grind exceeding small; though he sit, and wait with patience, with exactness grinds he all. it is, i believe, one of the most hopeful among the many hopeful signs of the times, that the civilised nations of europe and america are awakening slowly but surely to this truth. the civilised world is learning, thank god, more and more of the importance of physical science; year by year, thank god, it is learning to live more and more according to those laws of physical science, which are, as the great lord bacon said of old, none other than "vox dei in rebus revelata"--the word of god revealed in facts; and it is gaining by so doing, year by year, more and more of health and wealth; of peaceful and comfortable, even of graceful and elevating, means of life for fresh millions. if you want to know what the study of physical science has done for man, look, as a single instance, at the science of sanatory reform; the science which does not merely try to cure disease, and shut the stable-door after the horse is stolen, but tries to prevent disease; and, thank god! is succeeding beyond our highest expectations. or look at the actual fresh amount of employment, of subsistence, which science has, during the last century, given to men; and judge for yourselves whether the study of it be not one worthy of those who wish to help themselves, and, in so doing, to help their fellow-men. let me quote to you a passage from an essay urging the institution of schools of physical science for artisans, which says all i wish to say and more: "the discoveries of voltaic electricity, electromagnetism, and magnetic electricity, by volta, oersted, and faraday, led to the invention of electric telegraphy by wheatstone and others, and to the great manufactures of telegraph cables and telegraph wire, and of the materials required for them. the value of the cargo of the great eastern alone in the recent bombay telegraph expedition was calculated at three millions of pounds sterling. it also led to the employment of thousands of operators to transmit the telegraphic messages, and to a great increase of our commerce in nearly all its branches by the more rapid means of communication. the discovery of voltaic electricity further led to the invention of electro-plating, and to the employment of a large number of persons in that business. the numerous experimental researches on specific heat, latent heat, the tension of vapours, the properties of water, the mechanical effect of heat, etc., resulted in the development of steam-engines, and railways, and the almost endless employments depending upon their construction and use. about a quarter of a million of persons are employed on railways alone in great britain. the various original investigations on the chemical effects of light led to the invention of photography, and have given employment to thousands of persons who practise that process, or manufacture and prepare the various material and articles required in it. the discovery of chlorine by scheele led to the invention of the modern processes of bleaching, and to various improvements in the dyeing of the textile fabrics, and has given employment to a very large number of our lancashire operatives. the discovery of chlorine has also contributed to the employment of thousands of printers, by enabling esparto grass to be bleached and formed into paper for the use of our daily press. the numerous experimental investigations in relation to coal-gas have been the means of extending the use of that substance, and of increasing the employment of workmen and others connected with its manufacture. the discovery of the alkaline metals by davy, of cyanide of potassium, of nickel, phosphorus, the common acids, and a multitude of other substances, has led to the employment of a whole army of workmen in the conversion of those substances into articles of utility. the foregoing examples might be greatly enlarged upon, and a great many others might be selected from the sciences of physics and chemistry: but those mentioned will suffice. there is not a force of nature, nor scarcely a material substance that we employ, which has not been the subject of several, and in some cases of numerous, original experimental researches, many of which have resulted, in a greater or less degree, in increasing the employment for workmen and others." { } "all this may be very true. but of what practical use will physical science be to me?" let me ask in return: are none of you going to emigrate? if you have courage and wisdom, emigrate you will, some of you, instead of stopping here to scramble over each other's backs for the scraps, like black-beetles in a kitchen. and if you emigrate, you will soon find out, if you have eyes and common sense, that the vegetable wealth of the world is no more exhausted than its mineral wealth. exhausted? not half of it--i believe not a tenth of it--is yet known. could i show you the wealth which i have seen in a single tropic island, not sixty miles square--precious timbers, gums, fruits, what not, enough to give employment and wealth to thousands and tens of thousands, wasting for want of being known and worked-- then you would see what a man who emigrates may do, by a little sound knowledge of botany alone. and if not. suppose that any one of you, learning a little sound natural history, should abide here in britain to your life's end, and observe nothing but the hedgerow plants, he would find that there is much more to be seen in those mere hedgerow plants than he fancies now. the microscope will reveal to him in the tissues of any wood, of any seed, wonders which will first amuse him, then puzzle him, and at last (i hope) awe him, as he perceives that smallness of size interferes in no way with perfection of development, and that "nature," as has been well said, "is greatest in that which is least." and more. suppose that he went further still. suppose that he extended his researches somewhat to those minuter vegetable forms, the mosses, fungi, lichens; suppose that he went a little further still, and tried what the microscope would show him in any stagnant pool, whether fresh water or salt, of desmidiae, diatoms, and all those wondrous atomies which seem as yet to defy our classification into plants or animals. suppose he learnt something of this, but nothing of aught else. would he have gained no solid wisdom? he would be a stupider man than i have a right to believe any of my readers to be, if he had not gained thereby somewhat of the most valuable of treasures--namely, that inductive habit of mind, that power of judging fairly of facts, without which no good or lasting work will be done, whether in physical science, in social science, in politics, in philosophy, in philology, or in history. but more: let me urge you to study natural science, on grounds which may be to you new and unexpected--on social, i had almost said on political, grounds. we all know, and i trust we all love, the names of liberty, equality, and brotherhood. we feel, i trust, that these words are too beautiful not to represent true and just ideas; and that therefore they will come true, and be fulfilled, somewhen, somewhere, somehow. it may be in a shape very different from that which you, or i, or any man expects; but still they will be fulfilled. but if they are to come true, it is we, the individual men, who must help them to come true for the whole world, by practising them ourselves, when and where we can. and i tell you--that in becoming scientific men, in studying science and acquiring the scientific habit of mind, you will find yourselves enjoying a freedom, an equality, a brotherhood, such as you will not find elsewhere just now. freedom: what do we want freedom for? for this, at least; that we may be each and all able to think what we choose; and to say what we choose also, provided we do not say it rudely or violently, so as to provoke a breach of the peace. that last was mr. buckle's definition of freedom of speech. that was the only limit to it which he would allow; and i think that that is mr. john stuart mill's limit also. it is mine. and i think we have that kind of freedom in these islands as perfectly as any men are likely to have it on this earth. but what i complain of is, that when men have got the freedom, three out of four of them will not use it. what?--someone will answer--do you suppose that i will not say what i choose, and that i dare not speak my own mind to any man? doubtless. but are you sure first, that you think what you choose, or only what someone else chooses for you? are you sure that you make up your own mind before you speak, or let someone else make it up for you? your speech may be free enough, my good friend; and heaven forbid that it should be anything else: but are your thoughts free likewise? are you sure that, though you may hate bigotry in others, you are not somewhat of a bigot yourself? that you do not look at only one side of a question, and that the one which pleases you? that you do not take up your opinions at second hand, from some book or some newspaper, which after all only reflects your own feelings, your own opinions? you should ask yourselves that question, seriously and often: "are my thoughts really free?" no one values more highly than i do the advantage of a free press. but you must remember always that a newspaper editor, however honest or able, is no more infallible than the pope; that he may, just as you may, only see one side of a question, while any question is sure to have two sides, or perhaps three or four; and if you only see the side which suits you, day after day, month after month, you must needs become bigoted to it. your thoughts must needs run in one groove. they cannot (as mr. matthew arnold would say) "play freely round" a question; and look it all over, boldly, patiently, rationally, charitably. and i tell you that if you, or i, or any man, want to let our thoughts play freely round questions, and so escape from the tendency to become bigoted and narrow-minded which there is in every human being, then we must acquire something of that inductive habit of mind which the study of natural science gives. it is, after all, as professor huxley says, only common sense well regulated. but then it is well regulated; and how precious it is, if you can but get it. the art of seeing, the art of knowing what you see; the art of comparing, of perceiving true likenesses and true differences, and so of classifying and arranging what you see: the art of connecting facts together in your own mind in chains of cause and effect, and that accurately, patiently, calmly, without prejudice, vanity, or temper--this is what is wanted for true freedom of mind. but accuracy, patience, freedom from prejudice, carelessness for all except the truth, whatever the truth may be--are not these the virtues of a truly free spirit? then, as i said just now, i know no study so able to give that free habit of mind as the study of natural science. equality, too: whatever equality may or may not be just, or possible; this at least, is just, and i hope possible; that every man, every child, of every rank, should have an equal chance of education; an equal chance of developing all that is in him by nature; an equal chance of acquiring a fair knowledge of those facts of the universe which specially concern him; and of having his reason trained to judge of them. i say, whatever equal rights men may or may not have, they have this right. let every boy, every girl, have an equal and sound education. if i had my way, i would give the same education to the child of the collier and to the child of a peer. i would see that they were taught the same things, and by the same method. let them all begin alike, say i. they will be handicapped heavily enough as they go on in life, without our handicapping them in their first race. whatever stable they come out of, whatever promise they show, let them all train alike, and start fair, and let the best colt win. well: but there is a branch of education in which, even now, the poor man can compete fairly against the rich; and that is, natural science. in the first place, the rich, blind to their own interest, have neglected it hitherto in their schools; so that they have not the start of the poor man on that subject which they have on many. in the next place, natural science is a subject which a man cannot learn by paying for teachers. he must teach it himself, by patient observation, by patient common sense. and if the poor man is not the rich man's equal in those qualities, it must be his own fault, not his purse's. many shops have i seen about the world, in which fools could buy articles more or less helpful to them; but never saw i yet an observation-shop, nor a common-sense shop either. and if any man says, "we must buy books:" i answer, a poor man now can obtain better scientific books than a duke or a prince could sixty years ago, simply because then the books did not exist. when i was a boy i would have given much, or rather my father would have given much, if i could have got hold of such scientific books as are to be found now in any first-class elementary school. and if more expensive books are needed; if a microscope or apparatus is needed; can you not get them by the co-operative method, which has worked so well in other matters? can you not form yourselves into a natural science club, for buying such things and lending them round among your members; and for discussion also, the reading of scientific papers of your own writing, the comparing of your observations, general mutual help and mutual instructions? such societies are becoming numerous now, and gladly should i see one in every town. for in science, as in most matters, "as iron sharpeneth iron, so a man sharpeneth the countenance of his friend." and brotherhood: well, if you want that; if you want to mix with men, and men, too, eminently worth mixing with, on the simple ground that "a man's a man for a' that;" if you want to become the acquaintances, and--if you prove worthy--the friends, of men who will be glad to teach you all they know, and equally glad to learn from you anything you can teach them, asking no questions about you, save, first--is he an honest student of nature for her own sake? and next- -is he a man who will not quarrel, or otherwise behave in an unbrotherly fashion to his fellow-students?--if you want a ground of brotherhood with men, not merely in these islands, but in america, on the continent--in a word, all over the world--such as rank, wealth, fashion, or other artificial arrangements of the world cannot give and cannot take away; if you want to feel yourself as good as any man in theory, because you are as good as any man in practice, except those who are better than you in the same line, which is open to any and every man; if you wish to have the inspiring and ennobling feeling of being a brother in a great freemasonry which owns no difference of rank, of creed, or of nationality--the only freemasonry, the only international league which is likely to make mankind (as we all hope they will be some day) one--then become men of science. join the freemasonry in which hugh miller, the poor cromarty stonemason, in which michael faraday, the poor bookbinder's boy, became the companions and friends of the noblest and most learned on earth, looked up to by them not as equals merely but as teachers and guides, because philosophers and discoverers. do you wish to be great? then be great with true greatness; which is,--knowing the facts of nature, and being able to use them. do you wish to be strong? then be strong with true strength; which is, knowing the facts of nature, and being able to use them. do you wish to be wise? then be wise with true wisdom; which is, knowing the facts of nature, and being able to use them. do you wish to be free? then be free with true freedom; which is again, knowing the facts of nature, and being able to use them. i dare say some of my readers, especially the younger ones, will demur to that last speech of mine. well, i hope they will not be angry with me for saying it. i, at least, shall certainly not he angry with them. for when i was young i was very much of what i suspect is their opinion. i used to think one could get perfect freedom, and social reform, and all that i wanted, by altering the arrangements of society and legislation; by constitutions, and acts of parliament; by putting society into some sort of freedom-mill, and grinding it all down, and regenerating it so. and that something can be done by improved arrangements, something can be done by acts of parliament, i hold still, as every rational man must hold. but as i grew older, i began to see that if things were to be got right, the freedom-mill would do very little towards grinding them right, however well and amazingly it was made. i began to see that what sort of flour came out at one end of the mill, depended mainly on what sort of grain you had put in at the other; and i began to see that the problem was to get good grain, and then good flour would be turned out, even by a very clumsy old-fashioned sort of mill. and what do i mean by good grain? good men, honest men, accurate men, righteous men, patient men, self-restraining men, fair men, modest men. men who are aware of their own vast ignorance compared with the vast amount that there is to be learned in such a universe as this. men who are accustomed to look at both sides of a question; who, instead of making up their minds in haste like bigots and fanatics, wait like wise men, for more facts, and more thought about the facts. in one word, men who had acquired just the habit of mind which the study of natural science can give, and must give; for without it there is no use studying natural science; and the man who has not got that habit of mind, if he meddles with science, will merely become a quack and a charlatan, only fit to get his bread as a spirit-rapper, or an inventor of infallible pills. and when i saw that, i said to myself--i will train myself, by natural science, to the truly rational, and therefore truly able and useful, habit of mind; and more, i will, for it is my duty as an englishman, train every englishman over whom i can get influence in the same scientific habit of mind, that i may, if possible, make him, too, a rational and an able man. and, therefore, knowing that most of you, my readers--probably all of you, as you ought and must if you are britons, think much of social and political questions---therefore, i say, i entreat you to cultivate the scientific spirit by which alone you can judge justly of those questions. i ask you to learn how to "conquer nature by obeying her," as the great lord bacon said two hundred and fifty years ago. for so only will you in your theories and your movements, draw "bills which nature will honour"--to use mr. carlyle's famous parable--because they are according to her unchanging laws, and not have them returned on your hands, as too many theorists' are, with "no effects" written across their backs. take my advice for yourselves, dear readers, and for your children after you; for, believe me, i am showing you the way to true and useful, and, therefore, to just and deserved power. i am showing you the way to become members of what i trust will be--what i am certain ought to be--the aristocracy of the future. i say it deliberately, as a student of society and of history. power will pass more and more, if all goes healthily and well, into the hands of scientific men; into the hands of those who have made due use of that great heirloom which the philosophers of the seventeenth century left for the use of future generations, and specially of the teutonic race. for the rest, events seem but too likely to repeat themselves again and again all over the world, in the same hopeless circle. aristocracies of mere birth decay and die, and give place to aristocracies of mere wealth; and they again to "aristocracies of genius," which are really aristocracies of the noisiest, of mere scribblers and spouters, such as france is writhing under at this moment. and when these last have blown off their steam, with mighty roar, but without moving the engine a single yard, then they are but too likely to give place to the worst of all aristocracies, the aristocracy of mere "order," which means organised brute force and military despotism. and, after that, what can come, save anarchy, and decay, and social death? what else?--unless there be left in the nation, in the society, as the salt of the land, to keep it all from rotting, a sufficient number of wise men to form a true working aristocracy, an aristocracy of sound and rational science? if they be strong enough (and they are growing stronger day by day over the civilised world), on them will the future of that world mainly depend. they will rule, and they will act--cautiously we may hope, and modestly and charitably, because in learning true knowledge they will have learnt also their own ignorance, and the vastness, the complexity, the mystery of nature. but they will be able to rule, they will be able to act, because they have taken the trouble to learn the facts and the laws of nature. they will rule; and their rule, if they are true to themselves, will be one of health and wealth, and peace, of prudence and of justice. for they alone will be able to wield for the benefit of man the brute forces of nature; because they alone will have stooped, to "conquer nature by obeying her." so runs my dream. i ask my young readers to help towards making that dream a fact, by becoming (as many of them as feel the justice of my words) honest and earnest students of natural science. but now: why should i, as a clergyman, interest myself specially in the spread of natural science? am i not going out of my proper sphere to meddle with secular matters? am i not, indeed, going into a sphere out of which i had better keep myself, and all over whom i may have influence? for is not science antagonistic to religion? and, if so, what has a clergyman to do, save to warn the young against it, instead of attracting them towards it? first, as to meddling with secular matters. i grudge that epithet of "secular" to any matter whatsoever. but i do more; i deny it to anything which god has made, even to the tiniest of insects, the most insignificant atom of dust. to those who believe in god, and try to see all things in god, the most minute natural phenomenon cannot be secular. it must be divine; i say, deliberately, divine; and i can use no less lofty word. the grain of dust is a thought of god; god's power made it; god's wisdom gave it whatsoever properties or qualities it may possess; god's providence has put it in the place where it is now, and has ordained that it should be in that place at that moment, by a train of causes and effects which reaches back to the very creation of the universe. the grain of dust can no more go from god's presence, or flee from god's spirit, than you or i can. if it go up to the physical heaven, and float (as it actually often does) far above the clouds, in those higher strata of the atmosphere which the aeronaut has never visited, whither the alpine snow-peaks do not rise, even there it will be obeying physical laws which we term hastily laws of nature, but which are really the laws of god: and if it go down into the physical abyss; if it be buried fathoms, miles, below the surface, and become an atom of some rock still in the process of consolidation, has it escaped from god, even in the bowels of the earth? is it not there still obeying physical laws, of pressure, heat, crystallisation, and so forth, which are laws of god- -the will and mind of god concerning particles of matter? only look at all created things in this light--look at them as what they are, the expressions of god's mind and will concerning this universe in which we live--"the word of god," as bacon says, "revealed in facts"- -and then you will not fear physical science; for you will be sure that, the more you know of physical science, the more you will know of the works and of the will of god. at least, you will be in harmony with the teaching of the psalmist: "the heavens," says he, "declare the glory of god; and the firmament showeth his handiwork. there is neither speech nor language where their voices are not heard among them." so held the psalmist concerning astronomy, the knowledge of the heavenly bodies; and what he says of sun and stars is true likewise of the flowers around our feet, of which the greatest christian poet of modern times has said-- to me the meanest flower that grows may give thoughts that do lie too deep for tears. so, again, you will be in harmony with the teaching of st. paul, who told the romans "that the invisible things of god are clearly seen from the creation of the-world, being understood by the things that are made, even his eternal power and godhead;" and who told the savages of lycaonia that "god had not left himself without witness, in that he did good and sent men rain from heaven, and fruitful seasons, filling men's hearts with food and gladness." rain and fruitful seasons witnessed to all men of a father in heaven. and he who wishes to know how truly st. paul spoke, let him study the laws which produce and regulate rain and fruitful seasons, what we now call climatology, meteorology, geography of land and water. let him read that truly noble christian work, maury's "physical geography of the sea;" and see, if he be a truly rational man, how advanced science, instead of disproving, has only corroborated st. paul's assertion, and how the ocean and the rain-cloud, like the sun and stars, declare the glory of god. and if anyone undervalues the sciences which teach us concerning stones and plants and animals, or thinks that nothing can be learnt from them concerning god--allow one who has been from childhood only a humble, though he trusts a diligent student of these sciences--allow him, i say, to ask in all reverence, but in all frankness, who it was who said, "consider the lilies of the field, how they grow." "consider the birds of the air- -and how your heavenly father feedeth them." consider them. if he has bid you do so, can you do so too much? i know, of course, the special application which our lord made of these words. but i know, too, from experience, that the more you study nature, in all her forms the more you will find that the special application itself is deeper, wider, more literally true, more wonderful, more tender, and if i dare use such a word, more poetic, than the unscientific man can guess. but let me ask you further--do you think that our lord in that instance, and in those many instances in which he drew his parables and lessons from natural objects, was leading men's minds on to dangerous ground, and pointing out to them a subject of contemplation in the laws and processes of the natural world, and their analogy with those of the spiritual world, the kingdom of god--a subject of contemplation, i say, which it was not safe to contemplate too much? i appeal to your common sense. if he who spoke these words were (as i believe) none other than the creator of the universe, by whom all things were made, and without whom nothing was made that is made, do you suppose that he would have bid you to consider his universe, had it been dangerous for you to do so? do you suppose, moreover, that the universe, which he, the truth, the light, the love, has made, can be otherwise then infinitely worthy to be considered? or that the careful, accurate, and patient consideration of it, even to its minutest details, can be otherwise than useful to man, and can bear witness of aught, save the mind and character of him who made it? and if so, can it be a work unfit for, unworthy of, a clergyman--whose duty is to preach him to all, and in all ways,--to call on men to consider that physical world which, like the spiritual world, consists, holds together, by him, and lives and moves and has its being in him? and here i must pause to answer an objection which i have heard in my youth from many pious and virtuous people--better people in god's sight, than i, i fear, can pretend to be. they used to say, "this would be all very true if there were not a curse upon the earth." and then they seemed to deduce, from the fact of that curse, a vague notion (for it was little more) that this world was the devil's world, and that therefore physical facts could not be trusted, because they were disordered, and deceptive, and what not. now, in justice to the bible, and in justice to the church of england, i am bound to say that such a statement, or anything like it, is contrary to the doctrines of both. it is contrary to scripture. according to it, the earth is not cursed. for it is said in gen. viii. , "and the lord said, i will not again curse the ground any more for man's sake. while the earth remaineth, seed-time and harvest, cold and heat, summer and winter, day and night shall not cease." according to scripture, again, physical facts are not disordered. the psalmist says, "they continue this day according to their ordinance; for all things serve thee." and again, "thou hast made them fast for ever and ever. thou hast given them a law which cannot be broken." so does the bible (not to quote over again the passages which i have already given you from st. paul, and one greater than st. paul) declare the permanence of natural laws, and the trustworthiness of natural phenomena as obedient to god. and so does the church of england. for she has incorporated into her services that magnificent hymn, which our forefathers called the song of the three children; which is, as it were, the very flower and crown of the old testament; the summing up of all that is true and eternal in the old jewish faith; as true for us as for them: as true millions of years hence as it is now--which cries to all heaven and earth, from the skies above our heads to the green herb beneath our feet, "o all ye works of the lord, bless ye the lord; praise him and magnify him for ever." on that one hymn i take my stand. that is my charter as a student of natural science. as long as that is sung in an english church, i have a right to investigate nature boldly without stint or stay, and to call on all who have the will, to investigate her boldly likewise, and with socrates of old, to follow the logos whithersoever it leads. the logos. i must pause on that word. it meant at first, no doubt, simply speech, argument, reason. in the mind of socrates it had a deeper meaning, at which he only dimly guessed; which was seen more clearly by philo and the alexandrian jews; which was revealed in all its fulness to the beloved apostle st. john, till he gathered speech to tell men of a logos, a word, who was in the beginning with god, and was god; by whom all things were made, and without him was not anything made that was made; and how in him was life, and the life was the light of men; and that he was none other than jesus christ our lord. yes, that is the truth. and to that truth no man can add, and from it no man can take away. and as long as we believe that as long as we believe that in his light alone can we see light--as long as we believe that the light around us, whether physical or spiritual, is given by him without whom nothing is made--so long we shall not fear to meet light, so long we shall not fear to investigate life; for we shall know, however strange or novel, beautiful or awful, the discoveries we make may be, we are only following the word whithersoever he may lead us; and that he can never lead us amiss i. the soil of the field { } my dear readers, let me, before touching on the special subject of this paper, say a few words on that of the whole series. it is geology: that is, the science which explains to us the rind of the earth; of what it is made; how it has been made. it tells us nothing of the mass of the earth. that is, properly speaking, an astronomical question. if i may be allowed to liken this earth to a fruit, then astronomy will tell us--when it knows--how the fruit grew, and what is inside the fruit. geology can only tell us at most how its rind, its outer covering, grew, and of what it is composed; a very small part, doubtless, of all that is to be known about this planet. but as it happens, the mere rind of this earth-fruit which has, countless ages since, dropped, as it were, from the bosom of god, the eternal fount of life--the mere rind of this earth-fruit, i say, is so beautiful and so complex, that it is well worth our awful and reverent study. it has been well said, indeed, that the history of it, which we call geology, would be a magnificent epic poem, were there only any human interest in it; did it deal with creatures more like ourselves than stones, and bones, and the dead relics of plants and beasts. whether there be no human interest in geology; whether man did not exist on the earth during ages which have seen enormous geological changes, is becoming more and more an open question. but meanwhile all must agree that there is matter enough for interest--nay, room enough for the free use of the imagination, in a science which tells of the growth and decay of whole mountain-ranges, continents, oceans, whole tribes and worlds of plants and animals. and yet it is not so much for the vastness and grandeur of those scenes of the distant past, to which the science of geology introduces us, that i value it as a study, and wish earnestly to awaken you to its beauty and importance. it is because it is the science from which you will learn most easily a sound scientific habit of thought. i say most easily; and for these reasons. the most important facts of geology do not require, to discover them, any knowledge of mathematics or of chemical analysis; they may be studied in every bank, every grot, every quarry, every railway-cutting, by anyone who has eyes and common sense, and who chooses to copy the late illustrious hugh miller, who made himself a great geologist out of a poor stonemason. next, its most important theories are not, or need not be, wrapped up in obscure latin and greek terms. they may be expressed in the simplest english, because they are discovered by simple common sense. and thus geology is (or ought to be), in popular parlance, the people's science--the science by studying which, the man ignorant of latin, greek, mathematics, scientific chemistry, can yet become--as far as his brain enables him--a truly scientific man. but how shall we learn science by mere common sense? first. always try to explain the unknown by the known. if you meet something which you have not seen before, then think of the thing most like it which you have seen before; and try if that which you know explains the one will not explain the other also. sometimes it will; sometimes it will not. but if it will, no one has a right to ask you to try any other explanation. suppose, for instance, that you found a dead bird on the top of a cathedral tower, and were asked how you thought it had got there. you would say, "of course, it died up here." but if a friend said, "not so; it dropped from a balloon, or from the clouds;" and told you the prettiest tale of how the bird came to so strange an end, you would answer, "no, no; i must reason from what i know. i know that birds haunt the cathedral tower; i know that birds die; and therefore, let your story be as pretty as it may, my common sense bids me take the simplest explanation, and say--it died here." in saying that, you would be talking scientifically. you would have made a fair and sufficient induction (as it is called) from the facts about birds' habits and birds' deaths which you know. but suppose that when you took the bird up you found that it was neither a jackdaw, nor a sparrow nor a swallow, as you expected, but a humming-bird. then you would be adrift again. the fact of it being a humming-bird would be a new fact which you had not taken into account, and for which your old explanation was not sufficient; and you would have to try a new induction--to use your common sense afresh--saying, "i have not to explain merely how a dead bird got here, but how a dead humming-bird." and now, if your imaginative friend chimed in triumphantly with: "do you not see that i was right after all? do you not see that it fell from the clouds? that it was swept away hither, all the way from south america, by some south-westerly storm, and wearied out at last, dropped here to find rest, as in a sacred-place?" what would you answer? "my friend, that is a beautiful imagination; but i must treat it only as such, as long as i can explain the mystery more simply by facts which i do know. i do not know that humming-birds can be blown across the atlantic alive. i do know they are actually brought across the atlantic dead; are stuck in ladies' hats. i know that ladies visit the cathedral; and odd as the accident is, i prefer to believe, till i get a better explanation, that the humming-bird has simply dropped out of a lady's hat." there, again, you would be speaking common sense; and using, too, sound inductive method; trying to explain what you do not know from what you do know already. now, i ask of you to employ the same common sense when you read and think of geology. it is very necessary to do so. for in past times men have tried to explain the making of the world around them, its oceans, rivers, mountains, and continents, by i know not what of fancied cataclysms and convulsions of nature; explaining the unknown by the still more unknown, till some of their geological theories were no more rational, because no more founded on known facts, than that of the new zealand maories, who hold that some god, when fishing, fished up their islands out of the bottom of the ocean. but a sounder and wiser school of geologists now reigns; the father of whom, in england at least, is the venerable sir charles lyell. he was almost the first of englishmen who taught us to see--what common sense tells us- -that the laws which we see at work around us now have been most probably at work since the creation of the world; and that whatever changes may seem to have taken place in past ages, and in ancient rocks, should be explained, if possible, by the changes which are taking place now in the most recent deposits--in the soil of the field. and in the last forty years--since that great and sound idea has become rooted in the minds of students, and especially of english students, geology has thriven and developed, perhaps more than any other science; and has led men on to discoveries far more really astonishing and awful than all fancied convulsions and cataclysms. i have planned this series of papers, therefore, on sir charles lyell's method. i have begun by trying to teach a little about the part of the earth's crust which lies nearest us, which we see most often; namely, the soil; intending, if my readers do me the honour to read the papers which follow, to lead them downward, as it were, into the earth; deeper and deeper in each paper, to rocks and minerals which are probably less known to them than the soil in the fields. thus you will find i shall lead you, or try to lead you on, throughout the series, from the known to the unknown, and show you how to explain the latter by the former. sir charles lyell has, i see, in the new edition of his "student's elements of geology," begun his book with the uppermost, that is, newest, strata, or layers; and has gone regularly downwards in the course of the book to the lowest or earliest strata; and i shall follow his plan. i must ask you meanwhile to remember one law or rule, which seems to me founded on common sense; namely, that the uppermost strata are really almost always the newest; that when two or more layers, whether of rock or earth--or indeed two stones in the street, or two sheets on a bed, or two books on a table--any two or more lifeless things, in fact, lie one on the other, then the lower one was most probably put there first, and the upper one laid down on the lower. does that seem to you a truism? do i seem almost impertinent in asking you to remember it? so much the better. i shall be saved unnecessary trouble hereafter. but some one may say, and will have a right to say, "stop--the lower thing may have been thrust under the upper one." quite true: and therefore i said only that the lower one was most probably put there first. and i said "most probably," because it is most probable that in nature we should find things done by the method which costs least force, just as you do them. i will warrant that when you want to hide a thing, you lay something down on it ten times for once that you thrust it under something else. you may say, "what? when i want to hide a paper, say, under the sofa-cover, do i not thrust it under?" no, you lift up the cover, and slip the paper in, and let the cover fall on it again. and so, even in that case, the paper has got into its place first. now why is this? simply because in laying one thing on another you only move weight. in thrusting one thing under another, you have not only to move weight, but to overcome friction. that is why you do it, though you are hardly aware of it: simply because so you employ less force, and take less trouble. and so do clays and sands and stones. they are laid down on each other, and not thrust under each other, because thus less force is expended in getting them into place. there are exceptions. there are cases in which nature does try to thrust one rock under another. but to do that she requires a force so enormous, compared with what is employed in laying one rock on another, that (so to speak) she continually fails; and instead of producing a volcanic eruption, produces only an earthquake. of that i may speak hereafter, and may tell you, in good time, how to distinguish rocks which have been thrust in from beneath, from rocks which have been laid down from above, as every rock between london and birmingham or exeter has been laid down. that i only assert now. but i do not wish you to take it on trust from me. i wish to prove it to you as i go on, or to do what is far better for you: to put you in the way of proving it for yourself, by using your common sense. at the risk of seeming prolix, i must say a few more words on this matter. i have special reasons for it. until i can get you to "let your thoughts play freely" round this question of the superposition of soils and rocks, there will be no use in my going on with these papers. suppose then (to argue from the known to the unknown) that you were watching men cleaning out a pond. atop, perhaps, they would come to a layer of soft mud, and under that to a layer of sand. would not common sense tell you that the sand was there first, and that the water had laid down the mud on the top of it? then, perhaps, they might come to a layer of dead leaves. would not common sense tell you that the leaves were there before the sand above them? then, perhaps, to a layer of mud again. would not common sense tell you that the mud was there before the leaves? and so on down to the bottom of the pond, where, lastly, i think common sense would tell you that the bottom of the pond was there already, before all the layers which were laid down on it. is not that simple common sense? then apply that reasoning to the soils and rocks in any spot on earth. if you made a deep boring, and found, as you would in many parts of this kingdom, that the boring, after passing through the soil of the field, entered clays or loose sands, you would say the clays were there before the soil. if it then went down into sandstone, you would say--would you not?--that sandstone must have been here before the clay; and however thick--even thousands of feet- -it might be, that would make no difference to your judgment. if next the boring came into quite different rocks; into a different sort of sandstone and shales, and among them beds of coal, would you not say--these coal-beds must have been here before the sandstones? and if you found in those coal-beds dead leaves and stems of plants, would you not say--those plants must have been laid down here before the layers above them, just as the dead leaves in the pond were? if you then came to a layer of limestone, would you not say the same? and if you found that limestone full of shells and corals, dead, but many of them quite perfect, some of the corals plainly in the very place in which they grew, would you not say--these creatures must have lived down here before the coal was laid on top of them? and if, lastly, below the limestone you came to a bottom rock quite different again, would you not say--the bottom rock must have been here before the rocks on the top of it? and if that bottom rock rose up a few miles off, two thousand feet, or any other height, into hills, what would you say then? would you say: "oh, but the rock is not bottom rock; is not under the limestone here, but higher than it. so perhaps in this part it has made a shift, and the highlands are younger than the lowlands; for see, they rise so much higher?" would not that be as wise as to say that the bottom of the pond was not there before the pond mud, because the banks round the pond rose higher than the mud? now for the soil of the field. if we can understand a little about it, what it is made of, and how it got there, we shall perhaps be on the right road toward understanding what all england--and, indeed, the crust of this whole planet--is made of; and how its rocks and soils got there. but we shall best understand how the soil in the field was made, by reasoning, as i have said, from the known to the unknown. what do i mean? this: on the uplands are fields in which the soil is already made. you do not know how? then look for a field in which the soil is still being made. there are plenty in every lowland. learn how it is being made there; apply the knowledge which you learn from them to the upland fields which are already made. if there is, as there usually is, a river-meadow, or still better, an aestuary, near your town, you have every advantage for seeing soil made. thousands of square feet of fresh-made soil spread between your town and the sea; thousands more are in process of being made. you will see now why i have begun with the soil in the field; because it is the uppermost, and therefore latest, of all the layers; and also for this reason, that, if sir charles lyell's theory be true--as it is--then the soils and rocks below the soil of the field may have been made in the very same way in which the soil of the field is made. if so, it is well worth our while to examine it. you all know from whence the soil comes which has filled up, in the course of ages, the great aestuaries below london, stirling, chester, or cambridge. it is river mud and sand. the river, helped by tributary brooks right and left, has brought down from the inland that enormous mass. you know that. you know that every flood and freshet brings a fresh load, either of fine mud or of fine sand, or possibly some of it peaty matter out of distant hills. here is one indisputable fact from which to start. let us look for another. how does the mud get into the river? the rain carries it thither. if you wish to learn the first elements of geology by direct experiment, do this: the next rainy day--the harder it rains the better--instead of sitting at home over the fire, and reading a book about geology, put on a macintosh and thick boots, and get away, i care not whither, provided you can find there running water. if you have not time to get away to a hilly country, then go to the nearest bit of turnpike road, or the nearest sloping field, and see in little how whole continents are made, and unmade again. watch the rain raking and sifting with its million delicate fingers, separating the finer particles from the coarser, dropping the latter as soon as it can, and carrying the former downward with it toward the sea. follow the nearest roadside drain where it runs into a pond, and see how it drops the pebbles the moment it enters the pond, and then the sand in a fan-shaped heap at the nearest end; but carries the fine mud on, and holds it suspended, to be gradually deposited at the bottom in the still water; and say to yourself: perhaps the sands which cover so many inland tracts were dropped by water, very near the shore of a lake or sea, and by rapid currents. perhaps, again, the brick clays, which are often mingled with these sands, were dropped, like the mud in the pond, in deeper water farther from the shore, and certainly in stilt water. but more. suppose once more, then, that looking and watching a pond being cleared out, under the lowest layer of mud, you found--as you would find in any of those magnificent reservoirs so common in the lancashire hills--a layer of vegetable soil, with grass and brushwood rooted in it. what would you say but: the pond has not been always full. it has at some time or other been dry enough to let a whole copse grow up inside it? and if you found--as you will actually find along some english shores--under the sand hills, perhaps a bed of earth with shells and bones; under that a bed of peat; under that one of blue silt; under that a buried forest, with the trees upright and rooted; under that another layer of blue silt full of roots and vegetable fibre; perhaps under that again another old land surface with trees again growing in it; and under all the main bottom clay of the district--what would common sense tell you? i leave you to discover for yourselves. it certainly would not tell you that those trees were thrust in there by a violent convulsion, or that all those layers were deposited there in a few days, or even a few years; and you might safely indulge in speculations about the antiquity of the aestuary, and the changes which it has undergone, with which i will not frighten you at present. it will be fair reasoning to argue thus. you may not be always right in your conclusion, but still you will be trying fairly to explain the unknown by the known. but have rain and rivers alone made the soil? how very much they have done toward making it you will be able to judge for yourselves, if you will read the sixth chapter of sir charles lyell's new "elements of geology," or the first hundred pages of that admirable book, de la beche's "geological observer;" and last, but not least, a very clever little book called "rain and rivers," by colonel george greenwood. but though rain, like rivers, is a carrier of soil, it is more. it is a maker of soil, likewise; and by it mainly the soil of an upland field is made, whether it be carried down to the sea or not. if you will look into any quarry you will see that however compact the rock may be a few feet below the surface, it becomes, in almost every case, rotten and broken up as it nears the upper soil, till you often cannot tell where the rock ends and the soil begins. now this change has been produced by rain. first, mechanically, by rain in the shape of ice. the winter rain gets into the ground, and does by the rock what it has done by the stones of many an old building. it sinks into the porous stone, freezes there, expands in freezing, and splits and peels the stone with a force which is slowly but surely crumbling the whole of northern europe and america to powder. do you doubt me? i say nothing but what you can judge of yourselves. the next time you go up any mountain, look at the loose broken stones with which the top is coated, just underneath the turf. what has broken them up but frost? look again, as stronger proof, at the talus of broken stones--screes, as they call them in scotland; rattles, as we call them in devon--which lie along the base of many mountain cliffs. what has brought them down but frost? if you ask the country folk they will tell you whether i am right or not. if you go thither, not in the summer, but just after the winter's frost, you will see for yourselves, by the fresh frost-crop of newly-broken bits, that i am right. possibly you may find me to be even more right than is desirable, by having a few angular stones, from the size of your head to that of your body, hurled at you by the frost- giants up above. if you go to the alps at certain seasons, and hear the thunder of the falling rocks, and see their long lines--moraines, as they are called--sliding slowly down upon the surface of the glacier, then you will be ready to believe the geologist who tells you that frost, and probably frost alone, has hewn out such a peak as the matterhorn from some vast table-land; and is hewing it down still, winter after winter, till some day, where the snow alps now stand, there shall be rolling uplands of rich cultivable soil. so much for the mechanical action of rain, in the shape of ice. now a few words on its chemical action. rain water is seldom pure. it carries in it carbonic acid; and that acid, beating in shower after shower against the face of a cliff-- especially if it be a limestone cliff--weathers the rock chemically; changing (in case of limestone) the insoluble carbonate of lime into a soluble bicarbonate, and carrying that away in water, which, however clear, is still hard. hard water is usually water which has invisible lime in it; there are from ten to fifteen grains and more of lime in every gallon of limestone water. i leave you to calculate the enormous weight of lime which must be so carried down to the sea every year by a single limestone or chalk brook. you can calculate it, if you like, by ascertaining the weight of lime in each gallon, and the average quantity of water which comes down the stream in a day; and when your sum is done, you will be astonished to find it one not of many pounds, but probably of many tons, of solid lime, which you never suspected or missed from the hills around. again, by the time the rain has sunk through the soil, it is still less pure. it carries with it not only carbonic acid, but acids produced by decaying vegetables--by the roots of the grasses and trees which grow above; and they dissolve the cement of the rock by chemical action, especially if the cement be lime or iron. you may see this for yourselves, again and again. you may see how the root of a tree, penetrating the earth, discolours the soil with which it is in contact. you may see how the whole rock, just below the soil, has often changed in colour from the compact rock below, if the soil be covered with a dense layer of peat or growing vegetables. but there is another force at work, and quite as powerful as rain and rivers, making the soil of alluvial flats. perhaps it has helped, likewise, to make the soil of all the lowlands in these isles--and that is, the waves of the sea. if you ever go to parkgate, in cheshire, try if you cannot learn there a little geology. walk beyond the town. you find the shore protected for a long way by a sea-wall, lest it should be eaten away by the waves. what the force of those waves can be, even on that sheltered coast, you may judge--at least you could have judged this time last year--by the masses of masonry torn from their iron clampings during the gale of three winters since. look steadily at those rolled blocks, those twisted stanchions, if they are there still; and then ask yourselves- -it will be fair reasoning from the known to the unknown--what effect must such wave-power as that have had beating and breaking for thousands of years along the western coasts of england, scotland, ireland? it must have eaten up thousands of acres--whole shires, may be, ere now. its teeth are strong enough, and it knows neither rest nor pity, the cruel hungry sea. give it but time enough, and what would it not eat up? it would eat up, in the course of ages, all the dry land of this planet, were it not baffled by another counteracting force, of which i shall speak hereafter. as you go on beyond the sea-wall, you find what it is eating up. the whole low cliff is going visibly. but whither is it going? to form new soil in the aestuary. now you will not wonder how old harbours so often become silted up. the sea has washed the land into them. but more, the sea-currents do not allow the sands of the aestuary to escape freely out to sea. they pile it up in shifting sand-banks about the mouth of the aestuary. the prevailing sea-winds, from whatever quarter, catch up the sand, and roll it up into sand-hills. those sand-hills are again eaten down by the sea, and mixed with the mud of the tide-flats, and so is formed a mingled soil, partly of clayey mud, partly of sand; such a soil as stretches over the greater part of all our lowlands. now, why should not that soil, whether in england or in scotland, have been made by the same means as that of every aestuary. you find over great tracts of east scotland, lancashire, norfolk, etc., pure loose sand just beneath the surface, which looks as if it was blown sand from a beach. is it not reasonable to suppose that it is? you find rising out of many lowlands, crags which look exactly like old sea-cliffs eaten by the waves, from the base of which the waters have gone back. why should not those crags be old sea-cliffs? why should we not, following our rule of explaining the unknown by the known, assume that such they are till someone gives us a sound proof that they are not; and say--these great plains of england and scotland were probably once covered by a shallow sea, and their soils made as the soil of any tide-flat is being made now? but you may say, and most reasonably "the tide-flats are just at the sea-level. the whole of the lowland is many feet above the sea; it must therefore have been raised out of the sea, according to your theory: and what proofs have you of that?" well, that is a question both grand and deep, on which i shall not enter yet; but meanwhile, to satisfy you that i wish to play fair with you, i ask you to believe nothing but what you can prove for yourselves. let me ask you this: suppose that you had proof positive that i had fallen into the river in the morning; would not your meeting me in the evening be also proof positive that somehow or other i had in the course of the day got out of the river? i think you will accept that logic as sound. now if i can give you proof positive, proof which you can see with your own eyes, and handle with your own hands, and alas! often feel but too keenly with your own feet, that the whole of the lowlands were once beneath the sea; then will it not be certain that, somehow or other, they must have been raised out of the sea again? and that i propose to do in my next paper, when i speak of the pebbles in the street. meanwhile i wish you to face fairly the truly grand idea, which all i have said tends to prove true--that all the soil we see is made by the destruction of older soils, whether soft as clay, or hard as rock; that rain, rivers, and seas are perpetually melting and grinding up old land, to compose new land out of it; and that it must have been doing so, as long as rain, rivers, and seas have existed. "but how did the first land of all get made?" i can only reply: a natural question: but we can only answer that, by working from the known to the unknown. while we are finding out how these later lands were made and unmade, we may stumble on some hints as to how the first primeval continents rose out of the bosom of the sea. and thus i end this paper. i trust it has not been intolerably dull. but i wanted at starting to show my readers something of the right way of finding out truth on this and perhaps on all subjects; to make some simple appeals to your common sense; and to get you to accept some plain rules founded on common sense, which will be of infinite use to both you and me in my future papers. i hope, meanwhile, that you will agree with me, that there is plenty of geological matter to be seen and thought over in the neighbourhood of any town. be sure, that wherever there is a river, even a drain; and a stone quarry, or even a roadside bank; much more where there is a sea, or a tidal aestuary, there is geology enough to be learnt, to explain the greater part of the making of all the continents on the globe. ii. the pebbles in the street if you, dear reader, dwell in any northern town, you will almost certainly see paving courts and alleys, and sometimes--to the discomfort of your feet--whole streets, or set up as bournestones at corners, or laid in heaps to be broken up for road-metal, certain round pebbles, usually dark brown or speckled gray, and exceedingly tough and hard. some of them will be very large--boulders of several feet in diameter. if you move from town to town, from the north of scotland as far down as essex on the east, or as far down as shrewsbury and wolverhampton (at least) on the west, you will still find these pebbles, but fewer and smaller as you go south. it matters not what the rocks and soils of the country round may be. however much they may differ, these pebbles will be, on the whole, the same everywhere. but if your town be south of the valley of the thames, you will find, as far as i am aware, no such pebbles there. the gravels round you will be made up entirely of rolled chalk flints, and bits of beds immediately above or below the chalk. the blocks of "sarsden" sandstone--those of which stonehenge is built--and the "plum-pudding stones" which are sometimes found with them, have no kindred with the northern pebbles. they belong to beds above the chalk. now if, seeing such pebbles about your town, you inquire, like a sensible person who wishes to understand something of the spot on which he lives, whence they come, you will be shown either a gravel- pit or a clay-pit. in the gravel the pebbles and boulders lie mixed with sand, as they do in the railway cutting just south of shrewsbury; or in huge mounds of fine sweet earth, as they do in the gorge of the tay about dunkeld, and all the way up strathmore, where they form long grassy mounds--tomauns as they call them in some parts of scotland--askers as they call them in ireland. these mounds, with their sweet fresh turf rising out of heather and bog, were tenanted-- so scottish children used to believe--by fairies. he that was lucky might hear inside them fairy music, and, the jingling of the fairy horses' trappings. but woe to him if he fell asleep upon the mound, for he would be spirited away into fairyland for seven years, which would seem to him but one day. a strange fancy; yet not so strange as the actual truth as to what these mounds are, and how they came into their places. or again, you might find that your town's pebbles and boulders came out of a pit of clay, in which they were stuck, without any order or bedding, like plums and raisins in a pudding. this clay goes usually by the name of boulder-clay. you would see such near any town in cheshire and lancashire; or along leith shore, near edinburgh; or, to give one more instance out of hundreds, along the coast at scarborough. if you walk along the shore southward of that town, you will see, in the gullies of the cliff, great beds of sticky clay, stuffed full of bits of every rock between the lake mountains and scarborough, from rounded pebbles of most ancient rock down to great angular fragments of ironstone and coal. there, as elsewhere, the great majority of the pebbles have nothing to do with the rock on which the clay happens to lie, but have come, some of them, from places many miles away. now if we find spread over a low land pebbles composed of rocks which are only found in certain high lands, is it not an act of common sense to say--these pebbles have come from the highlands? and if the pebbles are rounded, while the rocks like them in the highlands always break off in angular shapes, is it not, again, an act of mere common sense to say--these pebbles were once angular, and have been rubbed round, either in getting hither or before they started hither? does all this seem to you mere truism, my dear reader? if so, i am sincerely glad to hear it. it was not so very long ago that such arguments would have been considered not only no truisms, but not even common sense. but to return, let us take, as an example, a sample of these boulder clay pebbles from the neighbourhood of liverpool and birkenhead, made by mr. de rance, the government geological surveyor: granite, greenstone, felspar porphyry, felstone, quartz rock (all igneous rocks, that is, either formed by, or altered by volcanic heat, and almost all found in the lake mountains), per cent. silurian grits (the common stones of the lake mountains deposited by water), per cent. ironstone, per cent. carboniferous limestone, per cent. permian or triassic sandstones, i.e. rocks immediately round liverpool, per cent. now, does not this sample show, as far as human common sense can be depended on, that the great majority of these stones come from the lake mountains, sixty or seventy miles north of liverpool? i think your common sense will tell you that these pebbles are not mere concretions; that is, formed out of the substance of the clay after it was deposited. the least knowledge of mineralogy would prove that. but, even if you are no mineralogist, common sense will tell you, that if they were all concreted out of the same clay, it is most likely that they would be all of the same kind, and not of a dozen or more different kinds. common sense will tell you, also, that if they were all concreted out of the same clay, it is a most extraordinary coincidence, indeed one too strange to be believed, if any less strange explanation can be found--that they should have taken the composition of different rocks which are found all together in one group of mountains to the northward. you will surely say--if this be granite, it has most probably come from a granite mountain; if this be grit, from a grit-stone mountain, and so on with the whole list. why--are we to go out of our way to seek improbable explanations, when there is a probable one staring us in the face? next--and this is well worth your notice--if you will examine the pebbles carefully, especially the larger ones, you will find that they are not only more or less rounded, but often scratched; and often, too, in more than one direction, two or even three sets of scratches crossing each other; marked, as a cat marks an elder stem when she sharpens her claws upon it; and that these scratches have not been made by the quarrymen's tools, but are old marks which exist--as you may easily prove for yourself--while the stone is still lying in its bed of clay. would it not be an act of mere common sense to say--these scratches have been made by the sharp points of other stones which have rubbed against the pebbles somewhere, and somewhen, with great force? so far so good. the next question is--how did these stones get into the clay? if we can discover that, we may also discover how they wore rounded and scratched. we must find a theory which will answer our question; and one which, as professor huxley would say, "will go on all-fours," that is, will explain all the facts of the case, and not only a few of them. what, then, brought the stones? we cannot, i think, answer that question, as some have tried to answer it, by saying that they were brought by noah's flood. for it is clear, that very violent currents of water would be needed to carry boulders, some of them weighing many tons, for many miles. now scripture says nothing of any such violent currents; and we have no right to put currents, or any other imagined facts, into scripture out of our own heads, and then argue from them as if not we, but the text of scripture had asserted their existence. but still, they may have been rolled hither by water. that theory certainly would explain their being rounded; though not their being scratched. but it will not explain their being found in the clay. recollect what i said in my first paper: that water drops its pebbles and coarser particles first, while it carries the fine clayey mud onward in solution, and only drops it when the water becomes still. now currents of such tremendous violence as to carry these boulder stones onward, would have carried the mud for many miles farther still; and we should find the boulders, not in clay, but lying loose together, probably on a hard rock bottom, scoured clean by the current. that is what we find in the beds of streams; that is just what we do not find in this case. but the boulders may have been brought by a current, and then the water may have become still, and the clay settled quietly round them. what? under them as well as over them? on that theory also we should find them only at the bottom of the clay. as it is, we find them scattered anywhere and everywhere through it, from top to bottom. so that theory will not do. indeed, no theory will do which supposes them to have been brought by water alone. try yourself, dear reader, and make experiments, with running water, pebbles, and mud. if you try for seven years, i believe, you will never contrive to make your pebbles lie about in your mud, as they lie about in every pit in the boulder clay. well then, there we are at fault, it seems. we have no explanation drawn from known facts which will do--unless we are to suppose, which i don't think you will do, that stones, clay, and all were blown hither along the surface of the ground, by primeval hurricanes, ten times worse than those of the west indies, which certainly will roll a cannon a few yards, but cannot, surely, roll a boulder stone a hundred miles. now, suppose that there was a force, an agent, known--luckily for you, not to you--but known too well to sailors and travellers; a force which is at work over the vast sheets of land at both the north and south poles; at work, too, on every high mountain range in the world, and therefore a very common natural force; and suppose that this force would explain all the facts, namely-- how the stones got here; how they were scratched and rounded; how they were imbedded in clay; because it is notoriously, and before men's eyes now, carrying great stones hundreds of miles, and scratching and rounding them also; carrying vast deposits of mud, too, and mixing up mud and stones just as we see them in the brick-pits,--would not our common sense have a right to try that explanation?--to suspect that this force, which we do not see at work in britain now, may have been at work here ages since? that would at least be reasoning from the known to the unknown. what state of things, then, do we find among the highest mountains; and over whole countries which, though not lofty, lie far enough north or south to be permanently covered with ice? we find, first, an ice-cap or ice-sheet, fed by the winter's snows, stretching over the higher land, and crawling downward and outward by its own weight, along the valleys, as glaciers. we find underneath the glaciers, first a moraine profonde, consisting of the boulders and gravel, and earth, which the glacier has ground off the hillsides, and is carrying down with it. these stones, of course, grind, scratch, and polish each other; and in like wise grind, scratch, and polish the rock over which they pass, under the enormous weight of the superincumbent ice. we find also, issuing from under each glacier a stream, carrying the finest mud, the result of the grinding of the boulders against each other and the glacier. we find, moreover, on the surface of the glaciers, moraines superieures--long lines of stones and dirt which had fallen from neighbouring cliffs, and are now travelling downward with the glaciers. their fate, if the glacier ends on land, is what was to be expected. the stones from above the glacier fall over the ice-cliff at its end, to mingle with those thrown out from underneath the glacier, and form huge banks of boulders, called terminal moraines, while the mud runs off, as all who have seen glaciers know, in a turbid torrent. their fate, again, is what was to be expected if the glacier ends, as it commonly does in arctic regions, in the sea. the ice grows out to sea-ward for more than a mile sometimes, about one-eighth of it being above water, and seven-eighths below, so that an ice-cliff one hundred feet high may project into water eight hundred feet deep. at last, when it gets out of its depth, the buoyancy of the water breaks it off in icebergs, which float away, at the mercy of tides and currents, often grounding again in shallower water, and ploughing the sea-bottom as they drag along it. these bergs carry stones and dirt, often in large quantities; so that, whenever a berg melts or capsizes, it strews its burden confusedly about the sea-floor. meanwhile the fine mud which is flowing out from under the ice goes out to sea likewise, colouring the water far out, and then subsiding as a soft tenacious ooze, in which the stones brought out by the ice are imbedded. and this ooze--so those who have examined it assert-- cannot be distinguished from the brick-clay, or fossiliferous boulder-clay, so common in the north. a very illustrious scandinavian explorer, visiting edinburgh, declared, as soon as he saw the sections of boulder-clay exhibited near that city, that this was the very substance which he saw forming in the spitzbergen ice- fiords. { } i have put these facts as simply and baldly as i can, in order that the reader may look steadily at them, without having his attention drawn off, or his fancy excited, by their real poetry and grandeur. indeed, it would have been an impertinence to have done otherwise; for i have never seen a live glacier, by land or sea, though i have seen many a dead one. and the public has had the opportunity, lately, of reading so many delightful books about "peaks, passes, and glaciers," that i am bound to suppose that many of my readers know as much, or more, about them than i do. but let us go a step farther; and, bearing in our minds what live glaciers are like, let us imagine what a dead glacier would be like; a glacier, that is, which had melted, and left nothing but its skeleton of stones and dirt. we should find the faces of the rock scored and polished, generally in lines pointing down the valleys, or at least outward from the centre of the highlands, and polished and scored most in their upland or weather sides. we should find blocks of rock left behind, and perched about on other rocks of a different kind. we should find in the valleys the old moraines left as vast deposits of boulder and shingle, which would be in time sawn through and sorted over by the rivers. and if the sea-bottom outside were upheaved, and became dry land, we should find on it the remains of the mud from under the glacier, stuck full of stones and boulders iceberg-dropped. this mud would be often very irregularly bedded; for it would have been disturbed by the ploughing of the icebergs, and mixed here and there with dirt which had fallen from them. moreover, as the sea became shallower and the mud-beds got awash one after the other, they would be torn about, re-sifted, and re-shaped by currents and by tides, and mixed with shore-sand ground out of shingle-beach, thus making confusion worse confounded. a few shells, of an arctic or northern type, would be found in it here and there. some would have lived near those later beaches, some in deeper water in the ancient ooze, wherever the iceberg had left it in peace long enough for sea-animals to colonise and breed in it. but the general appearance of the dried sea-bottom would be a dreary and lifeless waste of sands, gravels, loose boulders, and boulder-bearing clays; and wherever a boss of bare rock still stood up, it would be found ground down, and probably polished and scored by the ponderous icebergs which had lumbered over it in their passage out to sea. in a word, it would look exactly as vast tracts of the english, scotch, and irish lowlands must have looked before returning vegetation coated their dreary sands and clays with a layer of brown vegetable soil. thus, and i believe thus only, can we explain the facts connected with these boulder pebbles. no agent known on earth can have stuck them in the clay, save ice, which is known to do so still elsewhere. no known agent can have scratched them as they are scratched, save ice, which is known to do so still elsewhere. no known agent--certainly not, in my opinion, the existing rivers-- can have accumulated the vast beds of boulders which lie along the course of certain northern rivers; notably along the dee about aboyne--save ice bearing them slowly down from the distant summits of the grampians. no known agent, save ice, can have produced those rounded, and polished, and scored, and fluted rochers moutonnes "sheep-backed rocks"--so common in the lake district; so common, too, in snowdon, especially between the two lakes of llanberis; common in kerry; to be seen anywhere, as far as i have ascertained, around the scotch highlands, where the turf is cleared away from an unweathered surface of the rock, in the direction in which a glacier would have pressed against it had one been there. where these polishings and scorings are found in narrow glens, it is, no doubt, an open question whether some of them may not be the work of water. but nothing but the action of ice can have produced what i have seen in land-locked and quiet fords in kerry--ice-flutings in polished rocks below high-water mark, so large that i could lie down in one of them. nothing but the action of ice could produce what may be seen in any of our mountains- -whole sheets of rock ground down into rounded flats, irrespective of the lie of the beds, not in valleys, but on the brows and summits of mountains, often ending abruptly at the edge of some sudden cliff, where the true work of water, in the shape of rain and frost, is actually destroying the previous work of ice, and fulfilling the rule laid down (i think by professor geikie in his delightful book on scotch scenery as influenced by its geology), that ice planes down into flats, while water saws out into crags and gullies; and that the rain and frost are even now restoring scotch scenery to something of that ruggedness and picturesqueness which it must have lost when it lay, like greenland, under the indiscriminating grinding of a heavy sheet of ice. lastly; no known agent, save ice, will explain those perched boulders, composed of ancient hard rocks, which may be seen in so many parts of these islands and of the continent. no water power could have lifted those stones, and tossed them up high and dry on mountain ridges and promontories, upon rocks of a totally different kind. some of my readers surely recollect wordsworth's noble lines about these mysterious wanderers, of which he had seen many a one about his native hills: as a huge stone is sometimes seen to lie couched on the bald top of an eminence, wonder to all who do the same espy by what means it could thither come, and whence; so that it seems a thing endued with sense: like a sea-beast crawled forth, that on a shelf of rock or sand reposeth, there to sun itself. yes; but the next time you see such a stone, believe that the wonder has been solved, and found to be, like most wonders in nature, more wonderful than we guessed it to be. it is not a sea-beast which has crawled forth, but an ice-beast which has been left behind; lifted up thither by the ice, as surely as the famous pierre-a-bot, forty feet in diameter, and hundreds of boulders more, almost as large as cottages, have been carried by ice from the distant alps right across the lake of neufchatel, and stranded on the slopes of the jura, nine hundred feet above the lake. { } thus, i think, we have accounted for facts enough to make it probable that britain was once covered partly by an ice-sheet, as greenland is now, and partly, perhaps, by an icy sea. but, to make assurance more sure, let us look for new facts, and try whether our ice-dream will account for them also. let us investigate our case as a good medical man does, by "verifying his first induction." he says: at the first glance, i can see symptoms a, b, c. it is therefore probable that my patient has got complaint a. but if he has he ought to have symptom d also. if i find that, my guess will be yet more probable. he ought also to have symptom e, and so forth; and as i find successively each of these symptoms which are proper to a, my first guess will become more and more probable, till it reaches practical certainty. now let us do the same, and say--if this strange dream be true, and the lowlands of the north were once under an icy sea, ought we not to find sea-shells in their sands and clays? not abundantly, of course. we can understand that the sea-animals would be too rapidly covered up in mud, and too much disturbed by icebergs and boulders, to be very abundant. but still, some should surely be found here and there. doubtless; and if my northern-town readers will search the boulder- clay pits near them, they will most probably find a few shells, if not in the clay itself, yet in sand-beds mixed with them, and probably underlying them. and this is a notable fact, that the more species of shells they find, the more they will find--if they work out their names from any good book of conchology--of a northern type; of shells which notoriously, at this day, inhabit the colder seas. it is impossible for me here to enter at length on a subject on which a whole literature has been already written. those who wish to study it may find all that they need know, and more, in lyell's "student's elements of geology," and in chapter xii. of his "antiquity of man." they will find that if the evidence of scientific conchologists be worth anything, the period can be pointed out in the strata, though not of course in time, at which these seas began to grow colder, and southern and mediterranean shells to disappear, their places being taken by shells of a temperate, and at last of an arctic climate; which last have since retreated either toward their native north, or into cold water at great depths. from essex across to wales, from wales to the aestuary of the clyde, this fact has been verified again and again. and in the search for these shells, a fresh fact, and a most startling one, was discovered. they are to be found not only in the clay of the lowlands, but at considerable heights up the hills, showing that, at some time or other, these hills have been submerged beneath the sea. let me give one example, which any tourist into wales may see for himself. moel tryfaen is a mountain over carnarvon. now perched on the side of that mountain, fourteen hundred feet above the present sea-level, is an ancient sea-beach, five-and-thirty feet thick, lying on great ice-scratched boulders, which again lie on the mountain slates. it was discovered by the late mr. trimmer, now, alas! lost to geology. out of that beach fifty-seven different species of shells have been taken; eleven of them are now exclusively arctic, and not found in our seas; four of them are still common to the arctic seas and to our own; and almost all the rest are northern shells. fourteen hundred feet above the present sea: and that, it must be understood, is not the greatest height at which such shells may be found hereafter. for, according to professor ramsay, drift of the same kind as that on moel tryfaen is found at a height of two thousand three hundred feet. now i ask my readers to use their common sense over this astounding fact--which, after all, is only one among hundreds; to let (as mr. matthew arnold would well say) their "thought play freely" about it; and consider for themselves what those shells must mean. i say not may, but must, unless we are to believe in a "deus quidam deceptor," in a god who puts shells upon mountain-sides only to befool honest human beings, and gives men intellects which are worthless for even the simplest work. those shells must mean that that mountain, and therefore the mountains round it, must have been once fourteen hundred feet at least lower than they are now. that the sea in which they were sunk was far colder than now. that icebergs brought and dropped boulders round their flanks. that upon those boulders a sea- beach formed, and that dead shells were beaten into it from a sea- bottom close by. that, and no less, moel tryfaen must mean. but it must mean, also, a length of time which has been well called "appalling." a length of time sufficient to let the mountain sink into the sea. then length of time enough to enable those arctic shells to crawl down from the northward, settle, and propagate themselves generation after generation; then length of time enough to uplift their dead remains, and the beach, and the boulders, and all snowdonia, fourteen hundred feet into the air. and if anyone should object that the last upheaval may have been effected suddenly by a few tremendous earthquakes, we must answer--we have no proof of it. earthquakes upheave lands now only by slight and intermittent upward pulses; nay, some lands we know to rise without any earthquake pulses, but by simple, slow, upward swelling of a few feet in a century; and we have no reason, and therefore no right, to suppose that snowdonia was upheaved by any means or at any rate which we do not witness now; and therefore we are bound to allow, not only that there was a past "age of ice," but that that age was one of altogether enormous duration. but meanwhile some of you, i presume, will be ready to cry--stop! it may be our own weakness; but you are really going on too fast and too far for our small imaginations. have you not played with us, as well as argued with us, till you have inveigled us step by step into a conclusion which we cannot and will not believe? that all this land should have been sunk beneath an icy sea? that britain should have been as greenland is now? we can't believe it, and we won't. if you say so, like stout common-sense britons, who have a wholesome dread of being taken in with fine words and wild speculations, i assure you i shall not laugh at you even in private. on the contrary, i shall say--what i am sure every scientific man will say-- so much the better. that is the sort of audience which we want, if we are teaching natural science. we do not want haste, enthusiasm, gobe-moucherie, as the french call it, which is agape to snap up any new and vast fancy, just because it is new and vast. we want our readers to be slow, suspicious, conservative, ready to "gib," as we say of a horse, and refuse the collar up a steep place, saying--i must stop and think. i don't like the look of the path ahead of me. it seems an ugly place to get up. i don't know this road, and i shall not hurry over it. i must go back a few steps, and make sure. i must see whether it is the right road; whether there are not other roads, a dozen of them perhaps, which would do as well and better than this. this is the temper which finds out truth, slowly, but once and for all; and i shall be glad, not sorry, to see it in my readers. and i am bound to say that it has been by that temper that this theory has been worked out, and the existence of this past age of ice, or glacial epoch, has been discovered, through many mistakes, many corrections, and many changes of opinion about details, for nearly forty years of hard work, by many men, in many lands. as a very humble student of this subject, i may say that i have been looking these facts in the face earnestly enough for more than twenty years, and that i am about as certain that they can only be explained by ice, as i am that my having got home by rail can only be explained by steam. but i think i know what startles you. it is the being asked to believe in such an enormous change in climate, and in the height of the land above the sea. well--it is very astonishing, appalling--all but incredible, if we had not the facts to prove it. but of the facts there can be no doubt. there can be no doubt that the climate of this northern hemisphere has changed enormously more than once. there can be no doubt that the distribution of land and water, the shape and size of its continents and seas, have changed again and again. there can be no doubt that, for instance, long before the age of ice, the whole north of europe was much warmer than it is now. take greenland, for instance. disco island lies in baffin's bay, off the west coast of greenland, in latitude degrees, far within the arctic circle. now there certain strata of rock, older than the ice, have not been destroyed by the grinding of the ice-cap; and they are full of fossil plants. but of what kind of plants? of the same families as now grow in the warmer parts of the united states. even a tulip-tree has been found among them. now how is this to be explained? either we must say that the climate of greenland was then so much warmer than now, that it had summers probably as hot as those of new york; or we must say that these leaves and stems were floated thither from the united states. but if we say the latter, we must allow a change in the shape of the land which is enormous. for nothing now can float northward from the united states into baffin's bay. the polar current sets out of baffin's bay southward, bringing icebergs down, not leaves up, through davis's straits. and in any case we must allow that the hills of disco island were then the bottom of a sea: or how would the leaves have been deposited in them at all? so much for the change of climate and land which can be proved to have gone on in greenland. it has become colder. why should it not some day become warmer again? now for england. it can be proved, as far as common sense can prove anything, that england was, before the age of ice, much warmer than it is now, and grew gradually cooler and cooler, just as, while the age of ice was dying out, it grew warmer again. now what proof is there of that? this. underneath london--as, i dare say, many of you know--there lies four or five hundred feet of clay. but not ice-clay. anything but that, as you will see. it belongs to a formation late (geologically speaking), but somewhat older than those disco island beds. and what sort of fossils do we find in it? in the first place, the shells, which are abundant, are tropical-- nautili, cones, and such like. and more, fruits and seeds are found in it, especially at the isle of sheppey. and what are they? fruits of nipa palms, a form only found now at river-mouths in eastern india and the indian islands; anona-seeds; gourd-seeds; acacia fruits--all tropical again; and proteaceous plants too--of an australian type. surely your common sense would hint to you, that this london clay must be mud laid down off the mouth of a tropical river. but your common sense would be all but certain of that, when you found, as you would find, the teeth and bones of crocodiles and turtles, who come to land, remember, to lay their eggs; the bones, too, of large mammals, allied to the tapir of india and south america, and the water-hog of the cape. if all this does not mean that there was once a tropic climate and a tropic river running into some sea or other where london now stands, i must give up common sense and reason as deceitful and useless faculties; and believe nothing, not even the evidence of my own senses. and now, have i, or have i not, fulfilled the promise which i made-- rashly, i dare say some of you thought--in my first paper? have i, or have i not, made you prove to yourself, by your own common sense, that the lowlands of britain were underneath the sea in the days in which these pebbles and boulders were laid down over your plains? nay, have we not proved more? have we not found that that old sea was an icy sea? have we not wandered on, step by step, into a whole true fairyland of wonders? to a time when all england, scotland, and ireland were as greenland is now? when mud streams have rushed down from under glaciers on to a cold sea-bottom, when "ice, mast high, came floating by, as green as emerald?" when snowdon was sunk for at least fourteen hundred feet of its height? when (as i could prove to you, had i time) the peaks of the highest cumberland and scotch mountains alone stood out, as islets in a frozen sea? we want to get an answer to one strange question, and we have found a group of questions stranger still, and got them answered too. but so it is always in science. we know not what we shall discover. but this, at least, we know, that it will be far more wonderful than we had dreamed. the scientific explorer is always like saul of old, who set out simply to find his father's asses, and found them--and a kingdom besides. i should have liked to have told you more about this bygone age of ice. i should have liked to say something to you on the curious question--which is still an open one--whether there were not two ages of ice; whether the climate here did not, after perhaps thousands of years of arctic cold, soften somewhat for a while--a few thousand years, perhaps--and then harden again into a second age of ice, somewhat less severe, probably, than the first. i should have liked to have hinted at the probable causes of this change--indeed, of the age of ice altogether--whether it was caused by a change in the distribution of land and water, or by change in the height and size of these islands, which made them large enough, and high enough, to carry a sheet of eternal snow inland; or whether, finally, the age of ice was caused by an actual change in the position of the whole planet with regard to its orbit round the sun--shifting at once the poles and the tropics; a deep question that latter, on which astronomers, whose business it is, are still at work, and on which, ere young folk are old, they will have discovered, i expect, some startling facts. on that last question, i, being no astronomer, cannot speak. but i should have liked to have said somewhat on matters on which i have knowledge enough, at least, to teach you how much there is to be learnt. i should have liked to tell the student of sea-animals--how the ice-age helps to explain, and is again explained by, the remarkable discoveries which dr. carpenter and mr. wyville thompson have just made, in the deep-sea dredgings in the north atlantic. i should have liked to tell the botanist somewhat of the pro-glacial flora--the plants which lived here before the ice, and lasted, some of them at least, through all those ages of fearful cold, and linger still on the summits of snowdon, and the highest peaks of cumberland and scotland. i should have liked to have told the lovers of zoology about the animals which lived before the ice-- of the mammoth, or woolly elephant; the woolly rhinoceros, the cave lion and bear, the reindeer, the musk oxen, the lemmings and the marmots which inhabited britain till the ice drove them out southward, even into the south of france; and how as the ice retreated, and the climate became tolerable once more, some of them-- the mammoth and rhinoceros, the bison, the lion, and many another mighty beast reoccupied our lowlands, at a time when the hippopotamus, at least in summer, ranged freely from africa and spain across what was then dry land between france and england, and fed by the side of animals which have long since retreated to norway and to canada. i should have liked to tell the archaeologist of the human beings--probably from their weapons and their habits--of the same race as the present laplanders, who passed northward as the ice went back, following the wild reindeer herds from the south of france into our islands, which were no islands then, to be in their turn driven northward by stronger races from the east and south. but space presses, and i fear that i have written too much already. at least, i have turned over for you a few grand and strange pages in the book of nature, and taught you, i hope, a key by which to decipher their hieroglyphics. at least, i have, i trust, taught you to look, as i do, with something of interest, even of awe, upon the pebbles in the street. iii. the stones in the wall this is a large subject. for in the different towns of these islands, the walls are built of stones of almost every age, from the earliest to the latest; and the town-geologist may find a quite different problem to solve in the nearest wall, on moving from one town to another twenty miles off. all i can do, therefore, is to take one set of towns, in the walls of which one sort of stones is commonly found, and talk of them; taking care, of course, to choose a stone which is widely distributed. and such, i think, we can find in the so-called new red sandstone, which, with its attendant marls, covers a vast tract--and that a rich and busy one--of england. from hartlepool and the mouth of the tees, down through yorkshire and nottinghamshire; over the manufacturing districts of central england; down the valley of the severn; past bristol and the somersetshire flats to torquay in south devon; up north-westward through shropshire and cheshire; past liverpool and northward through lancashire; reappearing again, north of the lake mountains, about carlisle and the scotch side of the solway frith, stretches the new red sandstone plain, from under which everywhere the coal-bearing rocks rise as from a sea. it contains, in many places, excellent quarries of building-stone; the most famous of which, perhaps, are the well-known runcorn quarries, near liverpool, from which the old romans brought the material for the walls and temples of ancient chester, and from which the stone for the restoration of chester cathedral is being taken at this day. in some quarters, especially in the north-west of england, its soil is poor, because it is masked by that very boulder- clay of which i spoke in my last paper. but its rich red marls, wherever they come to the surface, are one of god's most precious gifts to this favoured land. on them, one finds oneself at once in a garden; amid the noblest of timber, wheat, roots, grass which is green through the driest summers, and, in the western counties, cider-orchards laden with red and golden fruit. i know, throughout northern europe, no such charming scenery, for quiet beauty and solid wealth, as that of the new red marls; and if i wished to show a foreigner what england was, i should take him along them, from yorkshire to south devon, and say--there. is not that a country worth living for,--and worth dying for if need be? another reason which i have for dealing with the new red sandstone is this--that (as i said just now) over great tracts of england, especially about the manufacturing districts, the town-geologist will find it covered immediately by the boulder clay. the townsman, finding this, would have a fair right to suppose that the clay was laid down immediately, or at least soon after, the sandstones or marls on which it lies; that as soon as the one had settled at the bottom of some old sea, the other settled on the top of it, in the same sea. a fair and reasonable guess, which would in many cases, indeed in most, be quite true. but in this case it would be a mistake. the sandstone and marls are immensely older than the boulder-clay. they are, humanly speaking, some four or five worlds older. what do i mean? this--that between the time when the one, and the time when the other, was made, the british islands, and probably the whole continent of europe, have changed four or five times; in shape; in height above the sea, or depth below it; in climate; in the kinds of plants and animals which have dwelt on them, or on their sea- bottoms. and surely it is not too strong a metaphor, to call such changes a change from an old world to a new one. mind. i do not say that these changes were sudden or violent. it is far more probable that they are only part and parcel of that vast but slow change which is going on everywhere over our whole globe. i think that will appear probable in the course of this paper. but that these changes have taken place, is my main thesis. the fact i assert; and i am bound to try and prove it. and in trying to do so, i shall no longer treat my readers, as i did in the first two papers, like children. i shall take for granted that they now understand something of the method by which geological problems are worked out; and can trust it, and me; and shall state boldly the conclusions of geologists, only giving proof where proof is specially needed. now you must understand that in england there are two great divisions of these new red sandstones, "trias," as geologists call them. an upper, called in germany keuper, which consists, atop, of the rich red marl, below them, of sandstones, and of those vast deposits of rock-salt, which have been long worked, and worked to such good purpose, that a vast subsidence of land has just taken place near nantwich in cheshire; and serious fears are entertained lest the town itself may subside, to fill up the caverns below, from whence the salt has been quarried. underneath these beds again are those which carry the building-stone of runcorn. now these beds altogether, in cheshire, at least, are about , feet thick; and were not laid down in a year, or in a century either. below them lies a thousand feet of sandstones, known in germany by the name of "bunter," from its mottled and spotted appearance. what lies under them again, does not concern us just now. i said that the geologists called these beds the trias; that is, the triple group. but as yet we have heard of only two parts of it. where is the third? not here, but in germany. there, between the keuper above and the bunter below, lies a great series of limestone beds, which, from the abundance of fossils which they contain, go by the name of muschelkalk. a long epoch must therefore have intervened between the laying down of the bunter and of the keuper. and we have a trace of that long epoch, even in england. the keuper lies, certainly, immediately on the bunter; but not always "conformably" on it. that is, the beds are not exactly parallel. the bunter had been slightly tilted, and slightly waterworn, before the keuper was laid on it. it is reasonable, therefore, to suppose, that the bunter in england was dry land, and therefore safe from fresh deposit, through ages during which it was deep enough beneath the sea in germany, to have the muschelkalk laid down on it. here again, then, as everywhere, we have evidence of time--time, not only beyond all counting, but beyond all imagining. and now, perhaps, the reader will ask--if i am to believe that all new land is made out of old land, and that all rocks and soils are derived from the wear and tear of still older rocks, off what land came this enormous heap of sands more than , feet thick in places, stretching across england and into germany? it is difficult to answer. the shape and distribution of land in those days were so different from what they are now, that the rocks which furnished a great deal of our sandstone may be now, for aught i know, a mile beneath the sea. but over the land which still stands out of the sea near us there has been wear and tear enough to account for any quantity of sand deposit. as a single instance--it is a provable and proven fact--as you may see from mr. ramsay's survey of north wales--that over a large tract to the south of snowdon, between port madoc and barmouth, there has been ground off and carried away a mass of solid rock , feet thick; thick enough, in fact, if it were there still, to make a range of mountains as high as the andes. it is a provable and proven fact that vast tracts of the centre of poor old ireland were once covered with coal-measures, which have been scraped off in likewise, deprived of inestimable mineral wealth. the destruction of rocks--"denudation" as it is called--in the district round malvern, is, i am told, provably enormous. indeed, it is so over all wales, north england, and west and north scotland. so there is enough of rubbish to be accounted for to make our new red sands. the round pebbles in it being, i believe, pieces of old red sandstone, may have come from the great old red sandstone region of south east wales and herefordshire. some of the rubbish, too, may have come from what is now the isle of anglesey. for you find in the beds, from the top to the bottom (at least in cheshire), particles of mica. now this mica could not have been formed in the sand. it is a definite crystalline mineral, whose composition is well known. it is only found in rocks which have been subjected to immense pressure, and probably to heat. the granites and mica-slates of anglesey are full of it; and from anglesey--as likely as from anywhere else--these thin scales of mica came. and that is about all that i can say on the matter. but it is certain that most of these sands were deposited in a very shallow water, and very near to land. sand and pebbles, as i said in my first paper, could not be carried far out to sea; and some of the beds of the bunter are full of rounded pebbles. nay, it is certain that their surface was often out of water. of that you may see very pretty proofs. you find these sands ripple-marked, as you do shore-sands now. you find cracks where the marl mud has dried in the sun: and, more, you find the little pits made by rain. of that i have no doubt. i have seen specimens, in which you could not only see at a glance that the marks had been made by the large drops of a shower, but see also from what direction the shower had come. these delicate markings must have been covered up immediately with a fresh layer of mud or sand. how long since? how long since that flag had seen the light of the sun, when it saw it once again, restored to the upper air by the pick of the quarryman? who can answer that? not i. fossils are very rare in these sands; it is not easy to say why. it may be that the red oxide of iron in them has destroyed them. few or none are ever found in beds in which it abounds. it is curious, too, that the keuper, which is all but barren of fossils in england, is full of them in wurtemberg, reptiles, fish, and remains of plants being common. but what will interest the reader are the footprints of a strange beast, found alike in england and in germany--the cheirotherium, as it was first named, from its hand-like feet; the labyrinthodon, as it is now named, from the extraordinary structure of its teeth. there is little doubt now, among anatomists, that the bones and teeth of the so-called labyrinthodon belong to the animal which made the footprints. if so, the creature must have been a right loathly monster. some think him to have been akin to lizards; but the usual opinion is that he was a cousin of frogs and toads. looking at his hands and other remains, one pictures him to oneself as a short, squat brute, as big as a fat hog, with a head very much the shape of a baboon, very large hands behind and small ones in front, waddling about on the tide flats of a sandy sea, and dragging after him, seemingly, a short tail, which has left its mark on the sand. what his odour was, whether he was smooth or warty, what he ate, and in general how he got his living, we know not. but there must have been something there for him to eat; and i dare say that he was about as happy and about as intellectual as the toad is now. remember always that there is nothing alive now exactly like him, or, indeed, like any animal found in these sandstones. the whole animal world of this planet has changed entirely more than once since the labyrinthodon waddled over the cheshire flats. a lizard, for instance, which has been found in the keuper, had a skull like a bird's, and no teeth--a type which is now quite extinct. but there is a more remarkable animal of which i must say a few words, and one which to scientific men is most interesting and significant. both near warwick, and near elgin in scotland, in central india, and in south africa, fossil remains are found of a family of lizards utterly unlike anything now living save one, and that one is crawling about, plentifully i believe--of all places in the world--in new zealand. how it got there; how so strange a type of creature should have died out over the rest of the world, and yet have lasted on in that remote island for long ages, ever since the days of the new red sandstone, is one of those questions--quite awful questions i consider them--with which i will not puzzle my readers. i only mention it to show them what serious questions the scientific man has to face, and to answer, if he can. only the next time they go to the zoological gardens in london, let them go to the reptile-house, and ask the very clever and courteous attendant to show them the sphenodons, or hatterias, as he will probably call them--and then look, i hope with kindly interest, at the oldest conservatives they ever saw, or are like to see; gentlemen of most ancient pedigree, who have remained all but unchanged, while the whole surface of the globe has changed around them more than once or twice. and now, of course, my readers will expect to hear something of the deposits of rock-salt, for which cheshire and its red rocks are famous. i have never seen them, and can only say that the salt does not, it is said by geologists, lie in the sandstone, but at the bottom of the red marl which caps the sandstone. it was formed most probably by the gradual drying up of lagoons, such as are depositing salt, it is said now, both in the gulf of tadjara, on the abyssinian frontier opposite aden, and in the runn of cutch, near the delta of the indus. if this be so, then these new red sandstones may be the remains of a whole sahara--a sheet of sandy and all but lifeless deserts, reaching from the west of england into germany, and rising slowly out of the sea; to sink, as we shall find, beneath the sea again. and now, as to the vast period of time--the four or five worlds, as i called it--which elapsed between the laying down of the new red sandstones and the laying down of the boulder-clays. i think this fact--for fact it is--may be better proved by taking readers an imaginary railway journey to london from any spot in the manufacturing districts of central england--begging them, meanwhile, to keep their eyes open on the way. and here i must say that i wish folks in general would keep their eyes a little more open when they travel by rail. when i see young people rolling along in a luxurious carriage, their eyes and their brains absorbed probably in a trashy shilling novel, and never lifted up to look out of the window, unconscious of all that they are passing--of the reverend antiquities, the admirable agriculture, the rich and peaceful scenery, the like of which no country upon earth can show; unconscious, too, of how much they might learn of botany and zoology, by simply watching the flowers along the railway banks and the sections in the cuttings: then it grieves me to see what little use people make of the eyes and of the understanding which god has given them. they complain of a dull journey: but it is not the journey which is dull; it is they who are dull. eyes have they, and see not; ears have they, and hear not; mere dolls in smart clothes, too many of them, like the idols of the heathen. but my readers, i trust, are of a better mind. so the next time they find themselves running up southward to london--or the reverse way-- let them keep their eyes open, and verify, with the help of a geological map, the sketch which is given in the following pages. of the "black countries"--the actual coal districts i shall speak hereafter. they are in england either shores or islands yet undestroyed, which stand out of the great sea of new red sandstone, and often carry along their edges layers of far younger rocks, called now permian, from the ancient kingdom of permia, in russia, where they cover a vast area. with them i will not confuse the reader just now, but will only ask him to keep his eye on the rolling plain of new red sands and marls past, say, birmingham and warwick. after those places, these sands and marls dip to the south-east, and other rocks and soils appear above them, one after another, dipping likewise towards the south-east--that is, toward london. first appear thin layers of a very hard blue limestone, full of shells, and parted by layers of blue mud. that rock runs in a broad belt across england, from whitby in yorkshire, to lyme in dorsetshire, and is known as lias. famous it is, as some readers may know, for holding the bones of extinct monsters--ichthyosaurs and plesiosaurs, such as the unlearned may behold in the lake at the crystal palace. on this rock lie the rich cheese pastures, and the best tracts of the famous "hunting shires" of england. lying on it, as we go south-eastward, appear alternate beds of sandy limestone, with vast depths of clay between them. these "oolites," or freestones, furnish the famous bath stone, the oxford stone, and the barnack stone of northamptonshire, of which some of the finest cathedrals are built--a stone only surpassed, i believe, by the caen stone, which comes from beds of the same age in normandy. these freestones and clays abound in fossils, but of kinds, be it remembered, which differ more and more from those of the lias beneath, as the beds are higher in the series, and therefore nearer. there, too, are found principally the bones of that extraordinary flying lizard, the pterodactyle, which had wings formed out of its fore-legs, on somewhat the same plan as those of a bat, but with one exception. in the bat, as any one may see, four fingers of the hand are lengthened to carry the wing, while the first alone is left free, as a thumb: but in the pterodactyle, the outer or "little" finger alone is lengthened, and the other four fingers left free--one of those strange instances in nature of the same effect being produced in widely different plants and animals, and yet by slightly different means, on which a whole chapter of natural philosophy--say, rather, natural theology--will have to be written some day. but now consider what this lias, and the oolites and clays upon it mean. they mean that the new red sandstone, after it had been dry land, or all but dry land (as is proved by the footprints of animals and the deposits of salt), was sunk again beneath the sea. each deposit of limestone signifies a long period of time, during which that sea was pure enough to allow reefs of coral to grow, and shells to propagate, at the bottom. each great band of clay signifies a long period, during which fine mud was brought down from some wasting land in the neighbourhood. and that land was not far distant is proved by the bones of the pterodactyle, of crocodiles, and of marsupials; by the fact that the shells are of shallow-water or shore species; by the presence, mixed with them, of fragments of wood, impressions of plants, and even wing-shells of beetles; and lastly, if further proof was needed, by the fact that in the "dirt-bed" of the isle of portland and the neighbouring shores, stumps of trees allied to the modern sago-palms are found as they grew in the soil, which, with them, has been covered up in layers of freshwater shale and limestone. a tropic forest has plainly sunk beneath a lagoon; and that lagoon, again, beneath the sea. and how long did this period of slow sinking go on? who can tell? the thickness of the lias and oolites together cannot be less than a thousand feet. considering, then, the length of time required to lay down a thousand feet of strata, and considering the vast difference between the animals found in them, and the few found in the new red sandstone, we have a right to call them another world, and that one which must have lasted for ages. after we pass oxford, or the vale of aylesbury, we enter yet another world. we come to a bed of sand, under which the freestones and their adjoining clays dip to the south-east. this is called commonly the lower greensand, though it is not green, but rich iron-red. then succeeds a band of stiff blue clay, called the gault, and then another bed of sand, the upper greensand, which is more worthy of the name, for it does carry, in most places, a band of green or "glauconite" sand. but it and the upper layers of the lower greensand also, are worth our attention; for we are all probably eating them from time to time in the form of bran. it had been long remarked that certain parts of these beds carried admirable wheatland; it had been remarked, too, that the finest hop- lands--those of farnham, for instance, and tunbridge--lay upon them: but that the fertile band was very narrow; that, as in the surrey moors, vast sheets of the lower greensand were not worth cultivation. what caused the striking difference? my beloved friend and teacher, the late dr. henslow, when professor of botany at cambridge, had brought to him by a farmer (so the story ran) a few fossils. he saw, being somewhat of a geologist and chemist, that they were not, as fossils usually are, carbonate of lime, but phosphate of lime--bone-earth. he said at once, as by an inspiration, "you have found a treasure--not a gold-mine, indeed, but a food-mine. this is bone-earth, which we are at our wits' end to get for our grain and pulse; which we are importing, as expensive bones, all the way from buenos ayres. only find enough of them, and you will increase immensely the food supply of england, and perhaps make her independent of foreign phosphates in case of war." his advice was acted on; for the british farmer is by no means the stupid personage which townsfolk are too apt to fancy him. this bed of phosphates was found everywhere in the greensand, underlying the chalk. it may be traced from dorsetshire through england to cambridge, and thence, i believe, into yorkshire. it may be traced again, i believe, all round the weald of kent and sussex, from hythe to farnham--where it is peculiarly rich--and so to eastbourne and beachey head; and it furnishes, in cambridgeshire, the greater part of those so-called "coprolites," which are used perpetually now for manure, being ground up, and then treated with sulphuric acid, till they become a "soluble super-phosphate of lime." so much for the useless "hobby," as some fancy it, of poking over old bones and stones, and learning a little of the composition of this earth on which god has placed us. how to explain the presence of this vast mass of animal matter, in one or two thin bands right across england, i know not. that the fossils have been rolled on a sea-beach is plain to those who look at them. but what caused so vast a destruction of animal life along that beach, must remain one of the buried secrets of the past. and now we are fast nearing another world, which is far younger than that coprolite bed, and has been formed under circumstances the most opposite to it. we are nearing, by whatever rail we approach london, the escarpment of the chalk downs. all readers, surely, know the white chalk, the special feature and the special pride of the south of england. all know its softly- rounded downs, its vast beech woods, its short and sweet turf, its snowy cliffs, which have given--so some say--to the whole island the name of albion--the white land. but all do not, perhaps, know that till we get to the chalk no single plant or animal has been found which is exactly like any plant or animal now known to be living. the plants and animals grow, on the whole, more and more like our living forms as we rise in the series of beds. but only above the chalk (as far as we yet know) do we begin to find species identical with those living now. this in itself would prove a vast lapse of time. we shall have a further proof of that vast lapse when we examine the chalk itself. it is composed--of this there is now no doubt--almost entirely of the shells of minute animalcules; and animalcules (i use an unscientific word for the sake of unscientific readers) like these, and in some cases identical with them, are now forming a similar deposit of mud, at vast depths, over the greater part of the atlantic sea-floor. this fact has been put out of doubt by recent deep-sea dredgings. a whole literature has been written on it of late. any reader who wishes to know it, need only ask the first geologist he meets; and if he has the wholesome instinct of wonder in him, fill his imagination with true wonders, more grand and strange than he is like to find in any fairy tale. all i have to do with the matter here is, to say that, arguing from the known to the unknown, from the atlantic deep- sea ooze which we do know about, to the chalk which we do not know about, the whole of the chalk must have been laid down at the bottom of a deep and still ocean, far out of the reach of winds, tides, and even currents, as a great part of the atlantic sea-floor is at this day. prodigious! says the reader. and so it is. prodigious to think that that shallow greensand shore, strewed with dead animals, should sink to the bottom of an ocean, perhaps a mile, perhaps some four miles deep. prodigious the time during which it must have lain as a still ocean-floor. for so minute are the living atomies which form the ooze, that an inch, i should say, is as much as we can allow for their yearly deposit; and the chalk is at least a thousand feet thick. it may have taken, therefore, twelve thousand years to form the chalk alone. a rough guess, of course, but one as likely to be two or three times too little as two or three times too big. such, or somewhat such, is the fact. it had long been suspected, and more than suspected; and the late discoveries of dr. carpenter and mr. wyville thompson have surely placed it beyond doubt. thus, surely, if we call the oolitic beds one new world above the new red sandstone, we must call the chalk a second new world in like wise. i will not trouble the reader here with the reasons why geologists connect the chalk with the greensands below it, by regular gradations, in spite of the enormous downward leap, from sea-shore to deep ocean, which the beds seem (but only seem) to have taken. the change--like all changes in geology--was probably gradual. not by spasmodic leaps and starts, but slowly and stately, as befits a god of order, of patience, and of strength, have these great deeds been done. but we have not yet done with new worlds or new prodigies on our way to london, as any londoner may ascertain for himself, if he will run out a few miles by rail, and look in any cutting or pit, where the surface of the chalk, and the beds which lie on it, are exposed. on the chalk lie--especially in the blackheath and woolwich district- -sands and clays. and what do they tell us? of another new world, in which the chalk has been lifted up again, to form gradually, doubtless, and at different points in succession, the shore of a sea. but what proof is there of this? the surface of the chalk is not flat and smooth, as it must have been when at the bottom of the sea. it is eaten out into holes and furrows, plainly by the gnawing of the waves; and on it lie, in many places, large rolled flints out of chalk which has been destroyed, beds of shore-shingle, beds of oysters lying as they grew, fresh or brackish water-shells standing as they lived, bits of lignite (fossil wood half turned to coal), and (as in katesgrove pits at reading) leaves of trees. proof enough, one would say, that the chalk had been raised till part of it at least became dry land, and carried vegetation. and yet we have not done. there is another world to tell of yet. for these beds (known as the woolwich and reading beds) dip under that vast bed of london clay, four hundred and more feet thick, which (as i said in my last chapter) was certainly laid down by the estuary of some great tropic river, among palm-trees and anonas, crocodiles and turtles. is the reader's power of belief exhausted? if not: there are to be seen, capping almost every high land round london, the remains of a fifth world. some of my readers may have been to ascot races, or to aldershot camp, and may recollect the table-land of the sandy moors, perfectly flat atop, dreary enough to those to whom they are not (as they have long been to me) a home and a work-field. those sands are several hundred feet thick. they lie on the london clay. and they represent--the reader must take geologists' word for it--a series of beds in some places thousands of feet thick, in the isle of wight, in the paris basin, in the volcanic country of the auvergne, in switzerland, in italy; a period during which the land must at first have swarmed with forms of tropic life, and then grown--but very gradually--more temperate, and then colder and colder still; till at last set in that age of ice, which spread the boulder pebbles over all rocks and soils indiscriminately, from the lake mountains to within a few miles of london. for everywhere about those ascot moors, the top of the sands has been ploughed by shore-ice in winter, as they lay a-wash in the shallow sea; and over them, in many places, is spread a thin sheet of ice gravel, more ancient, the best geologists think, than the boulder and the boulder-clay. if any of my readers ask how long the period was during which those sands of ascot heath and aldershot have been laid down, i cannot tell. but this we can tell. it was long enough to see such changes in land and sea, that maps representing europe during the greater part of that period (as far as we can guess at it) look no more like europe than like america or the south sea islands. and this we can tell besides: that that period was long enough for the swiss alps to be lifted up at least , feet of their present height. and that was a work which--though god could, if he willed it, have done it in a single day--we have proof positive was not done in less than ages, beside which the mortal life of man is as the life of the gnat which dances in the sun. and all this, and more--as may be proved from the geology of foreign countries--happened between the date of the boulder-clay, and that of the new red sandstone on which it rests. iv. the coal in the fire my dear town-dwelling readers, let me tell you now something of a geological product well known, happily, to all dwellers in towns, and of late years, thanks to railroad extension, to most dwellers in country districts: i mean coal. coal, as of course you know, is commonly said to be composed of vegetable matter, of the leaves and stems of ancient plants and trees--a startling statement, and one which i do not wish you to take entirely on trust. i shall therefore spend a few pages in showing you how this fact--for fact it is--was discovered. it is a very good example of reasoning from the known to the unknown. you will have a right to say at first starting, "coal is utterly different in look from leaves and stems. the only property which they seem to have in common is that they can both burn." true. but difference of mere look may be only owing to a transformation, or series of transformations. there are plenty in nature quite as great, and greater. what can be more different in look, for instance, than a green field of wheat and a basket of loaves at the baker's? and yet there is, i trust, no doubt whatsoever that the bread has been once green wheat, and that the green wheat has been transformed into bread--making due allowance, of course, for the bone-dust, or gypsum, or alum with which the worthy baker may have found it profitable to adulterate his bread, in order to improve the digestion of her majesty's subjects. but you may say, "yes, but we can see the wheat growing, flowering, ripening, reaped, ground, kneaded, baked. we see, in the case of bread, the processes of the transformation going on: but in the case of coal we do not see the wood and leaves being actually transformed into coal, or anything like it." now suppose we laid out the wheat on a table in a regular series, such as you may see in many exhibitions of manufactures; beginning with the wheat plant at one end, and ending with the loaf at the other; and called in to look at them a savage who knew nothing of agriculture and nothing of cookery--called in, as an extreme case, the man in the moon, who certainly can know nothing of either; for as there is neither air nor water round the moon, there can be nothing to grow there, and therefore nothing to cook--and suppose we asked him to study the series from end to end. do you not think that the man in the moon, if he were half as shrewd as crofton croker makes him in his conversation with daniel o'rourke, would answer after due meditation, "how the wheat plant got changed into the loaf i cannot see from my experience in the moon: but that it has been changed, and that the two are the same thing i do see, for i see all the different stages of the change." and so i think you may say of the wood and the coal. the man in the moon would be quite reasonable in his conclusion; for it is a law, a rule, and one which you will have to apply again and again in the study of natural objects, that however different two objects may look in some respects, yet if you can find a regular series of gradations between them, with all shades of likeness, first to one of them and then to the other, then you have a fair right to suppose them to be only varieties of the same species, the same kind of thing, and that, therefore, they have a common origin. that sounds rather magniloquent. let me give you a simple example. suppose you had come into britain with brute, the grandson of aeneas, at that remote epoch when (as all archaeologists know who have duly read geoffrey of monmouth and the arthuric legends) britain was inhabited only by a few giants. now if you had met giants with one head, and also giants with seven heads, and no others, you would have had a right to say, "there are two breeds of giants here, one-headed and seven-headed." but if you had found, as jack the giant-killer (who belongs to the same old cycle of myths) appears to have found, two-headed giants also, and three-headed, and giants, indeed, with any reasonable number of heads, would you not have been justified in saying, "they are all of the same breed, after all; only some are more capitate, or heady, than others!" i hope that you agree to that reasoning; for by it i think we arrive most surely at a belief in the unity of the human race, and that the negro is actually a man and a brother. if the only two types of men in the world were an extreme white type, like the norwegians, and an extreme black type, like the negros, then there would be fair ground for saying, "these two types have been always distinct; they are different races, who have no common origin." but if you found, as you will find, many types of man showing endless gradations between the white man and the negro, and not only that, but endless gradations between them both and a third type, whose extreme perhaps is the chinese--endless gradations, i say, showing every conceivable shade of resemblance or difference, till you often cannot say to what type a given individual belongs; and all of them, however different from each other, more like each other than they are like any other creature upon earth; then you are justified in saying, "all these are mere varieties of one kind. however distinct they are now, they were probably like each other at first, and therefore all probably had a common origin." that seems to me sound reasoning, and advanced natural science is corroborating it more and more daily. now apply the same reasoning to coal. you may find about the world-- you may see even in england alone--every gradation between coal and growing forest. you may see the forest growing in its bed of vegetable mould; you may see the forest dead and converted into peat, with stems and roots in it; that, again, into sunken forests, like those to be seen below high-water mark on many coasts of this island. you find gradations between them and beds of lignite, or wood coal; then gradations between lignite and common or bituminous coal; and then gradations between common coal and culm, or anthracite, such as is found in south wales. have you not a right to say, "these are all but varieties of the same kind of thing--namely, vegetable matter? they have a common origin--namely, woody fibre. and coal, or rather culm, is the last link in a series of transformations from growing vegetation?" this is our first theory. let us try to verify it, as scientific men are in the habit of doing, by saying, if that be true, then something else is likely to be true too. if coal has all been vegetable soil, then it is likely that some of it has not been quite converted into shapeless coal. it is likely that there will be vegetable fibre still to be seen here and there; perhaps leaves, perhaps even stems of trees, as in a peat bog. let us look for them. you will not need to look far. the coal, and the sands and shales which accompany the coal, are so full of plant-remains, that three hundred species were known to adolphe brongniart as early as , and that number has largely increased since. now one point is specially noticeable about these plants of the coal; namely, that they may at least have grown in swamps. first, you will be interested if you study the coal flora, with the abundance, beauty, and variety of the ferns. now ferns in these islands grow principally in rocky woods, because there, beside the moisture, they get from decaying vegetable or decaying rock, especially limestone, the carbonic acid which is their special food, and which they do not get on our dry pastures, and still less in our cultivated fields. but in these islands there are two noble species, at least, which are true swamp-ferns; the lastraea thelypteris, which of old filled the fens, but is now all but extinct; and the osmunda, or king-fern, which, as all know, will grow wherever it is damp enough about the roots. in hampshire, in devon, and cornwall, and in the southwest of ireland, the king-fern too is a true swamp fern. but in the tropics i have seen more than once noble tree-ferns growing in wet savannahs at the sea-level, as freely as in the mountain-woods; ferns with such a stem as some of the coal ferns had, some fifteen feet in height, under which, as one rode on horseback, one saw the blazing blue sky, as through a parasol of delicate lace, as men might have long ages since have seen it, through the plumed fronds of the ferns now buried in the coal, had there only been a man then created to enjoy its beauty. next we find plants called by geologists calamites. there is no doubt now that they are of the same family as our equiseta, or horse- tails, a race which has, over most parts of the globe, dwindled down now from twenty or thirty feet in height, as they were in the old coal measures, to paltry little weeds. the tallest equisetum in england--the beautiful e. telmateia--is seldom five feet high. but they, too, are mostly mud and swamp plants; and so may the calamites have been. the lepidodendrons, again, are without doubt the splendid old representatives of a family now dwindled down to such creeping things as our club-mosses, or lycopodiums. now it is a certain fact, which can be proved by the microscope, that a very great part of the best coal is actually made up of millions of the minute seeds of club- mosses, such as grow--a few of them, and those very small--on our moors; a proof, surely, not only of the vast amount of the vegetation in the coal-making age, but also of the vast time during which it lasted. the lepidodendra may have been fifty or sixty feet high. there is not a lycopodium in the world now, i believe, five feet high. but the club-mosses are now, in these islands and elsewhere, lovers of wet and peaty soils, and so may their huger prototypes have been, in the old forests of the coal. of the sigillariae we cannot say as much with certainty, for botanists are not agreed as to what low order of flowerless plants they belong. but that they rooted in clay beds there is proof, as you will hear presently. and as to the conifers, or pine-like trees--the dadoxylon, of which the pith goes by the name of sternbergia, and the uncertain tree which furnishes in some coal-measures bushels of a seed connected with that of the yew--we may suppose that they would find no more difficulty in growing in swamps than the cypress, which forms so large a portion of the vegetation in the swamps of the southern united states. i have given you these hints, because you will naturally wish to know what sort of a world it was in which all these strange plants grew and turned into coal. my answer is, that it was most probably just like the world in which we are living now, with the one exception that the plants and animals are different. it was the fashion a few years since to explain the coal--like other phenomena of geology--by some mere hypothesis of a state of things quite unlike what we see now. we were brought up to believe that in the carboniferous, or coal-bearing era, the atmosphere was intensely moist and hot, and overcharged with carbonic acid, which had been poured out from the interior of the planet by volcanic eruptions, or by some other convulsion. i forget most of it now: and really there is no need to remember; for it is all, i verily believe, a dream--an attempt to explain the unknown not by the known, but by the still more unknown. you may find such theories lingering still in sensational school-books, if you like to be unscientific. if you like, on the other hand, to be scientific you will listen to those who tell you that instead of there having been one unique carboniferous epoch, with a peculiar coal-making climate, all epochs are carboniferous if they get the chance; that coal is of every age, from that of the scotch and english beds, up to the present day. the great coal-beds along the rocky mountains, for instance, are tertiary--that is, later than the chalk. coal is forming now, i doubt not, in many places on the earth, and would form in many more, if man did not interfere with the processes of wild nature, by draining the fens, and embanking the rivers. let me by a few words prove this statement. they will give you, beside, a fresh proof of sir charles lyell's great geological rule-- that the best way to explain what we see in ancient rocks is to take for granted, as long as we can do so fairly, that things were going on then very much as they are going on now. when it was first seen that coal had been once vegetable, the question arose--how did all these huge masses of vegetable matter get there? the yorkshire and derbyshire coal-fields, i hear, cover or square miles; the lancashire about . how large the north wales and the scotch fields are i cannot say. but doubtless a great deal more coal than can be got at lies under the sea, especially in the north of wales. coal probably exists over vast sheets of england and france, buried so deeply under later rocks, that it cannot be reached by mining. as an instance, a distinguished geologist has long held that there are beds of coal under london itself, which rise, owing to a peculiar disturbance of the strata, to within , or , feet of the surface, and that we or our children may yet see coal-mines in the marshes of the thames. and more, it is a provable fact that only a portion of the coal measures is left. a great part of ireland must once have been covered with coal, which is now destroyed. indeed, it is likely that the coal now known of in europe and america is but a remnant of what has existed there in former ages, and has been eaten away by the inroads of the sea. now whence did all that enormous mass of vegetable soil come? off some neighbouring land, was the first and most natural answer. it was a rational one. it proceeded from the known to the unknown. it was clear that these plants had grown on land; for they were land- plants. it was clear that there must have been land close by, for between the beds of coal, as you all know, the rock is principally coarse sandstone, which could only have been laid down (as i have explained to you already) in very shallow water. it was natural, then, to suppose that these plants and trees had been swept down by rivers into the sea, as the sands and muds which buried them had been. and it was known that at the mouths of certain rivers--the mississippi, for instance--vast rafts of dead floating trees accumulated; and that the bottoms of the rivers were often full of snags, etc.; trees which had grounded, and stuck in the mud; and why should not the coal have been formed in the same way? because--and this was a serious objection--then surely the coal would be impure--mixed up with mud and sand, till it was not worth burning. instead of which, the coal is usually pure vegetable, parted sharply from the sandstone which lies on it. the only other explanation was, that the coal vegetation had grown in the very places where it was found. but that seemed too strange to be true, till that great geologist, sir w. logan--who has since done such good work in canada- -showed that every bed of coal had a bed of clay under it, and that that clay always contained fossils called stigmaria. then it came out that the stigmaria in the under clay had long filaments attached to them, while when found in the sandstones or shales, they had lost their filaments, and seemed more or less rolled--in fact, that the natural place of the stigmaria was in the under clay. then mr. binney discovered a tree--a sigillaria, standing upright in the coal- measures with its roots attached. those roots penetrated into the under clay of the coal; and those roots were stigmarias. that seems to have settled the question. the sigillarias, at least, had grown where they were found, and the clay beneath the coal-beds was the original soil on which they had grown. just so, if you will look at any peat bog you will find it bottomed by clay, which clay is pierced everywhere by the roots of the moss forming the peat, or of the trees, birches, alders, poplars, and willows, which grow in the bog. so the proof seemed complete, that the coal had been formed out of vegetation growing where it was buried. if any further proof for that theory was needed, it would be found in this fact, most ingeniously suggested by mr. boyd dawkins. the resinous spores, or seeds of the lepidodendra make up--as said above--a great part of the bituminous coal. now those spores are so light, that if the coal had been laid down by water, they would have floated on it, and have been carried away; and therefore the bituminous coal must have been formed, not under water, but on dry land. i have dwelt at length on these further arguments, because they seem to me as pretty a specimen as i can give my readers of that regular and gradual induction, that common-sense regulated, by which geological theories are worked out. but how does this theory explain the perfect purity of the coal? i think sir c. lyell answers that question fully in p. of his "student's elements of geology." he tells us that the dense growths of reeds and herbage which encompass the margins of forest-covered swamps in the valley and delta of the mississippi, in passing through them, are filtered and made to clear themselves entirely before they reach the areas in which vegetable matter may accumulate for centuries, forming coal if the climate be favourable; and that in the cypress-swamps of that region no sediment mingles with the vegetable matter accumulated from the decay of trees and semi-aquatic plants; so that when, in a very dry season, the swamp is set on fire, pits are burnt into the ground many feet deep, or as far as the fire can go down without reaching water, and scarcely any earthy residuum is left; just as when the soil of the english fens catches fire, red-hot holes are eaten down through pure peat till the water-bearing clay below is reached. but the purity of the water in peaty lagoons is observable elsewhere than in the delta of the mississippi. what can be more transparent than many a pool surrounded by quaking bogs, fringed, as they are in ireland, with a ring of white water-lilies, which you dare not stoop to pick, lest the peat, bending inward, slide you down into that clear dark gulf some twenty feet in depth, bottomed and walled with yielding ooze, from which there is no escape? most transparent, likewise, is the water of the west indian swamps. though it is of the colour of coffee, or rather of dark beer, and so impregnated with gases that it produces fever or cholera when drunk, yet it is--at least when it does not mingle with the salt water--so clear, that one might see every marking on a boa- constrictor or alligator, if he glided along the bottom under the canoe. but now comes the question--even if all this be true, how were the forests covered up in shale and sandstone, one after another? by gradual sinking of the land, one would suppose. if we find, as we may find in a hundred coal-pits, trees rooted as they grew, with their trunks either standing up through the coal, and through the sandstone above the coal; their bark often remaining as coal while their inside is filled up with sandstone, has not our common-sense a right to say--the land on which they grew sank below the water-line; the trees were killed; and the mud and sand which were brought down the streams enveloped their trunks? as for the inside being full of sandstone, have we not all seen hollow trees? do we not all know that when a tree dies its wood decays first, its bark last? it is so, especially in the tropics. there one may see huge dead trees with their bark seemingly sound, and their inside a mere cavern with touchwood at the bottom; into which caverns one used to peep with some caution. for though one might have found inside only a pair of toucans, or parrots, or a whole party of jolly little monkeys, one was quite as likely to find a poisonous snake four or five feet long, whose bite would have very certainly prevented me having the pleasure of writing this book. now is it not plain that if such trees as that sunk, their bark would be turned into lignite, and at last into coal, while their insides would be silted up with mud and sand? thus a core or pillar of hard sandstone would be formed, which might do to the collier of the future what they are too apt to do now in the newcastle and bristol collieries. for there, when the coal is worked out below, the sandstone stems--"coal-pipes" as the colliers call them--in the roof of the seam, having no branches, and nothing to hold them up but their friable bark of coal, are but too apt to drop out suddenly, killing or wounding the hapless men below. or again, if we find--as we very often find--as was found at parkfield colliery, near wolverhampton, in the year --a quarter of an acre of coal-seam filled. with stumps of trees as they grew, their trunks broken off and lying in every direction, turned into coal, and flattened, as coal-fossils so often are, by the weight of the rock above--should we not have a right to say--these trees were snapped off where they grew by some violent convulsion; by a storm, or by a sudden inrush of water owing to a sudden sinking of the land, or by the very earthquake shock itself which sank the land? but what evidence have we of such sinkings? the plain fact that you have coal-seam above coal-seam, each with its bed of under-clay; and that therefore the land must have sunk ere the next bed of soil could have been deposited, and the next forest have grown on it. in one of the rocky mountain coal-fields there are more than thirty seams of coal, each with its under-clay below it. what can that mean but thirty or more subsidences of the land, and the peat of thirty or more forests or peat-mosses, one above the other? and now if any reader shall say, subsidence? what is this quite new element which you have brought into your argument? you told us that you would reason from the known to the unknown. what do we know of subsidence? you offered to explain the thing which had gone on once by that which is going on now. where is subsidence going on now upon the surface of our planet? and where, too, upheaval, such as would bring us these buried forests up again from under the sea-level, and make them, like our british coal-field, dry land once more? the answer is--subsidence and elevation of the land are common now, probably just as common as they were in any age of this planet's history. to give two instances, made now notorious by the writings of geologists. as lately as a single earthquake shock in cutch, at the mouth of the indus, sunk a tract of land larger than the lake of geneva in some places to a depth of eighteen feet, and converted it into an inland sea. the same shock raised, a few miles off, a corresponding sheet of land some fifty miles in length, and in some parts sixteen miles broad, ten feet above the level of the alluvial plain, and left it to be named by the country-people the "ullah bund," or bank of god, to distinguish it from the artificial banks in the neighbourhood. again: in the valley of the mississippi--a tract which is now, it would seem, in much the same state as central england was while our coal-fields were being laid down--the earthquakes of - caused large lakes to appear suddenly in many parts of the district, amid the dense forests of cypress. one of these, the "sunk country," near new madrid, is between seventy and eighty miles in length, and thirty miles in breadth, and throughout it, as late as , "dead trees were conspicuous, some erect in the water, others fallen, and strewed in dense masses over the bottom, in the shallows, and near the shore." i quote these words from sir charles lyell's "principles of geology" ( th edit.), vol. i. p. . and i cannot do better than advise my readers, if they wish to know more of the way in which coal was formed, to read what is said in that book concerning the delta of the mississippi, and its strata of forests sunk where they grew, and in some places upraised again, alternating with beds of clay and sand, vegetable soil, recent sea-shells, and what not, forming, to a depth of several hundred feet, just such a mass of beds as exists in our own coal-fields at this day. if, therefore, the reader wishes to picture to himself the scenery of what is now central england, during the period when our coal was being laid down, he has only, i believe, to transport himself in fancy to any great alluvial delta, in a moist and warm climate, favourable to the growth of vegetation. he has only to conceive wooded marshes, at the mouth of great rivers, slowly sinking beneath the sea; the forests in them killed by the water, and then covered up by layers of sand, brought down from inland, till that new layer became dry land, to carry a fresh crop of vegetation. he has thus all that he needs to explain how coal-measures were formed. i myself saw once a scene of that kind, which i should be sorry to forget; for there was, as i conceived, coal, making, or getting ready to be made, before my eyes: a sheet of swamp, sinking slowly into the sea; for there stood trees, still rooted below high-water mark, and killed by the waves; while inland huge trees stood dying, or dead, from the water at their roots. but what a scene--a labyrinth of narrow creeks, so narrow that a canoe could not pass up, haunted with alligators and boa-constrictors, parrots and white herons, amid an inextricable confusion of vegetable mud, roots of the alder-like mangroves, and tangled creepers hanging from tree to tree; and overhead huge fan-palms, delighting in the moisture, mingled with still huger broad-leaved trees in every stage of decay. the drowned vegetable soil of ages beneath me; above my head, for a hundred feet, a mass of stems and boughs, and leaves and flowers, compared with which the richest hothouse in england was poor and small. but if the sinking process which was going on continued a few hundred years, all that huge mass of wood and leaf would be sunk beneath the swamp, and covered up in mud washed down from the mountains, and sand driven in from the sea; to form a bed many feet thick, of what would be first peat, then lignite, and last, it may be, coal, with the stems of killed trees standing up out of it into the new mud and sand-beds above it, just as the sigillariae and other stems stand up in the coal-beds both of britain and of nova scotia; while over it a fresh forest would grow up, to suffer the same fate--if the sinking process went on--as that which had preceded it. that was a sight not easily to be forgotten. but we need not have gone so far from home, at least, a few hundred years ago, to see an exactly similar one. the fens of norfolk and cambridgeshire, before the rivers were embanked, the water pumped off, the forests felled, and the reed-beds ploughed up, were exactly in the same state. the vast deposits of peat between cambridge and the sea, often filled with timber-trees, either fallen or upright as they grew, and often mixed with beds of sand or mud, brought down in floods, were formed in exactly the same way; and if they had remained undrained, then that slow sinking, which geologists say is going on over the whole area of the fens, would have brought them gradually, but surely, below the sea-level, to be covered up by new forests, and converted in due time into coal. and future geologists would have found--they may find yet, if, which god forbid, england should become barbarous and the trees be thrown out of cultivation--instead of fossil lepidodendra and sigillariae, calamites and ferns, fossil ashes and oaks, alders and poplars, bulrushes and reeds. almost the only fossil fern would have been that tall and beautiful lastraea thelypteris, once so abundant, now all but destroyed by drainage and the plough. we need not, therefore, fancy any extraordinary state of things on this planet while our english coal was being formed. the climate of the northern hemisphere--britain, at least, and nova scotia--was warmer than now, to judge from the abundance of ferns; and especially of tree-ferns; but not so warm, to judge from the presence of conifers (trees of the pine tribe), as the tropics. moreover, there must have been, it seems to me, a great scarcity of animal-life. insects are found, beautifully preserved; a few reptiles, too, and land-shells; but very few. and where are the traces of such a swarming life as would be entombed were a tropic forest now sunk; which is found entombed in many parts of our english fens? the only explanation which i can offer is this--that the club-mosses, tree- ferns, pines, and other low-ranked vegetation of the coal afforded little or no food for animals, as the same families of plants do to this day; and if creatures can get nothing to eat, they certainly cannot multiply and replenish the earth. but, be that as it may, the fact that coal is buried forest is not affected. meanwhile, the shape and arrangements of sea and land must have been utterly different from what they are now. where was that great land, off which great rivers ran to deposit our coal-measures in their deltas? it has been supposed, for good reasons, that north-western france, belgium, holland, and germany were then under the sea; that denmark and norway were joined to scotland by a continent, a tongue of which ran across the centre of england, and into ireland, dividing the northern and southern coal-fields. but how far to the west and north did that old continent stretch? did it, as it almost certainly did long ages afterwards, join greenland and north america with scotland and norway? were the northern fields of nova scotia, which are of the same geological age as our own, and contain the same plants, laid down by rivers which ran off the same continent as ours? who can tell now? that old land, and all record of it, save what these fragmentary coal-measures can give, are buried in the dark abyss of countless ages; and we can only look back with awe, and comfort ourselves with the thought--let time be ever so vast, yet time is not eternity. one word more. if my readers have granted that all for which i have argued is probable, they will still have a right to ask for further proof. they will be justified in saying: "you say that coal is transformed vegetable matter; but can you show us how the transformation takes place? is it possible according to known natural laws?" the chemist must answer that. and he tells us that wood can become lignite, or wood-coal, by parting with its oxygen, in the shape of carbonic acid gas, or choke-damp; and then common or bituminous coal, by parting with its hydrogen, chiefly in the form of carburetted hydrogen--the gas with which we light our streets. that is about as much as the unscientific reader need know. but it is a fresh corroboration of the theory that coal has been once vegetable fibre, for it shows how vegetable fibre can, by the laws of nature, become coal. and it certainly helps us to believe that a thing has been done, if we are shown that it can be done. this fact explains, also, why in mines of wood-coal carbonic acid, i.e. choke-damp, alone is given off. for in the wood-coal a great deal of the hydrogen still remains. in mines of true coal, not only is choke-damp given off, but that more terrible pest of the miners, fire-damp, or explosive carburetted hydrogen and olefiant gases. now the occurrence of that fire-damp in mines proves that changes are still going on in the coal: that it is getting rid of its hydrogen, and so progressing toward the state of anthracite or culm--stone-coal as it is sometimes called. in the pennsylvanian coal-fields some of the coal has actually done this, under the disturbing force of earthquakes; for the coal, which is bituminous, like our common coal, to the westward where the strata are horizontal, becomes gradually anthracite as it is tossed and torn by the earthquake faults of the alleghany and appalachian mountains. and is a further transformation possible? yes; and more than one. if we conceive the anthracite cleared of all but its last atoms of oxygen, hydrogen, and nitrogen, till it has become all but pure carbon, it would become--as it has become in certain rocks of immense antiquity, graphite--what we miscall black-lead. and, after that, it might go through one transformation more, and that the most startling of all. it would need only perfect purification and crystallisation to become--a diamond; nothing less. we may consider the coal upon the fire as the middle term of a series, of which the first is live wood, and the last diamond; and indulge safely in the fancy that every diamond in the world has probably, at some remote epoch, formed part of a growing plant. a strange transformation; which will look to us more strange, more truly poetical, the more steadily we consider it. the coal on the fire; the table at which i write--what are they made of? gas and sunbeams; with a small percentage of ash, or earthy salts, which need hardly be taken into account. gas and sunbeams. strange, but true. the life of the growing plant--and what that life is who can tell?-- laid hold of the gases in the air and in the soil; of the carbonic acid, the atmospheric air, the water--for that too is gas. it drank them in through its rootlets: it breathed them in through its leaf- pores, that it might distil them into sap, and bud, and leaf, and wood. but it has to take in another element, without which the distillation and the shaping could never have taken place. it had to drink in the sunbeams--that mysterious and complex force which is for ever pouring from the sun, and making itself partly palpable to our senses as heat and light. so the life of the plant seized the sunbeams, and absorbed them, buried them in itself--no longer as light and heat, but as invisible chemical force, locked up for ages in that woody fibre. so it is. lord lytton told us long ago, in a beautiful song, how the wind and the beam loved the rose. but nature's poetry was more beautiful than man's. the wind and the beam loved the rose so well that they made the rose--or rather, the rose took the wind and the beam, and built up out of them, by her own inner life, her exquisite texture, hue, and fragrance. what next? the rose dies; the timber tree dies; decays down into vegetable fibre, is buried, and turned to coal: but the plant cannot altogether undo its own work. even in death and decay it cannot set free the sunbeams imprisoned in its tissue. the sun-force must stay, shut up age after age, invisible, but strong; working at its own prison-cells; transmuting them, or making them capable of being transmuted by man, into the manifold products of coal--coke, petroleum, mineral pitch, gases, coal-tar, benzole, delicate aniline dyes, and what not, till its day of deliverance comes. man digs it, throws it on the fire, a black, dead-seeming lump. a corner, an atom of it, warms till it reaches the igniting point; the temperature at which it is able to combine with oxygen. and then, like a dormant live thing, awaking after ages to the sense of its own powers, its own needs, the whole lump is seized, atom after atom, with an infectious hunger for that oxygen which it lost centuries since in the bottom of the earth. it drinks the oxygen in at every pore; and burns. and so the spell of ages is broken. the sun-force bursts its prison- cells, and blazes into the free atmosphere, as light and heat once more; returning in a moment into the same forms in which it entered the growing leaf a thousand centuries since. strange it all is, yet true. but of nature, as of the heart of man, the old saying stands--that truth is stranger than fiction. v. the lime in the mortar i shall presume in all my readers some slight knowledge about lime. i shall take for granted, for instance, that all are better informed than a certain party of australian black fellows were a few years since. in prowling on the track of a party of english settlers, to see what they could pick up, they came--oh joy!--on a sack of flour, dropped and left behind in the bush at a certain creek. the poor savages had not had such a prospect of a good meal for many a day. with endless jabbering and dancing, the whole tribe gathered round the precious flour-bag with all the pannikins, gourds, and other hollow articles it could muster, each of course with a due quantity of water from the creek therein, and the chief began dealing out the flour by handfuls, beginning of course with the boldest warriors. but, horror of horrors, each man's porridge swelled before his eyes, grew hot, smoked, boiled over. they turned and fled, man, woman, and child, from before that supernatural prodigy; and the settlers coming back to look for the dropped sack, saw a sight which told the whole tale. for the poor creatures, in their terror, had thrown away their pans and calabashes, each filled with that which it was likely to contain, seeing that the sack itself had contained, not flour, but quick-lime. in memory of which comi-tragedy, that creek is called to this day, "flour-bag creek." now i take for granted that you are all more learned than these black fellows, and know quick-lime from flour. but still you are not bound to know what quick-lime is. let me explain it to you. lime, properly speaking, is a metal, which goes among chemists by the name of calcium. but it is formed, as you all know, in the earth, not as a metal, but as a stone, as chalk or limestone, which is a carbonate of lime; that is, calcium combined with oxygen and carbonic-acid gases. in that state it will make, if it is crystalline and hard, excellent building stone. the finest white marble, like that of carrara in italy, of which the most delicate statues are carved, is carbonate of lime altered and hardened by volcanic heat. but to make mortar of it, it must be softened and then brought into a state in which it can be hardened again; and ages since, some man or other, who deserves to rank as one of the great inventors, one of the great benefactors of his race, discovered the art of making lime soft and hard again; in fact of making mortar. the discovery was probably very ancient; and made, probably like most of the old discoveries, in the east, spreading westward gradually. the earlier greek buildings are cyclopean, that is, of stone fitted together without mortar. the earlier egyptian buildings, though the stones are exquisitely squared and polished, are put together likewise without mortar. so, long ages after, were the earlier roman buildings, and even some of the later. the famous aqueduct of the pont du gard, near nismes, in the south of france, has, if i recollect right, no mortar whatever in it. the stones of its noble double tier of circular arches have been dropped into their places upon the wooden centres, and stand unmoved to this day, simply by the jamming of their own weight; a miracle of art. but the fact is puzzling; for these romans were the best mortar makers of the world. we cannot, i believe, surpass them in the art even now; and in some of their old castles, the mortar is actually to this day harder and tougher than the stones which it holds together. and they had plenty of lime at hand if they had chosen to make mortar. the pont du gard crosses a limestone ravine, and is itself built of limestone. but i presume the cunning romans would not trust mortar made from that coarse nummulite limestone, filled with gritty sand, and preferred, with their usual carefulness, no mortar at all to bad. but i must return, and tell my readers, in a few words, the chemical history of mortar. if limestone be burnt, or rather roasted, in a kiln, the carbonic acid is given off--as you may discover by your own nose; as many a poor tramp has discovered too late, when, on a cold winter night, he has lain down by the side of the burning kiln to keep himself warm, and woke in the other world, stifled to death by the poisonous fumes. the lime then gives off its carbonic acid, and also its water of crystallisation, that is, water which it holds (as do many rocks) locked up in it unseen, and only to be discovered by chemical analysis. it is then anhydrous--that is, waterless--oxide of lime, what we call quick-lime; that which figured in the comi-tragedy of "flour-bag creek;" and then, as you may find if you get it under your nails or into your eyes, will burn and blister like an acid. this has to be turned again into a hard and tough artificial limestone, in plain words, into mortar; and the first step is to slack it--that is, to give it back the water which it has lost, and for which it is as it were thirsting. so it is slacked with water, which it drinks in, heating itself and the water till it steams and swells in bulk, because it takes the substance of the water into its own substance. slacked lime, as we all know, is not visibly wetter than quick-lime; it crumbles to a dry white powder in spite of all the water which it contains. then it must be made to set, that is, to return to limestone, to carbonate of lime, by drinking in the carbonic acid from water and air, which some sorts of lime will do instantly, setting at once, and being therefore used as cements. but the lime usually employed must be mixed with more or less sand to make it set hard: a mysterious process, of which it will be enough to tell the reader that the sand and lime are said to unite gradually, not only mechanically, that is, by sticking together; but also in part chemically--that is, by forming out of themselves a new substance, which is called silicate of lime. be that as it may, the mortar paste has now to do two things; first to dry, and next to take up carbonic acid from the air and water, enough to harden it again into limestone: and that it will take some time in doing. a thick wall, i am informed, requires several years before it is set throughout, and has acquired its full hardness, or rather toughness; and good mortar, as is well known, will acquire extreme hardness with age, probably from the very same cause that it did when it was limestone in the earth. for, as a general rule, the more ancient the strata is in which the limestone is found, the harder the limestone is; except in cases where volcanic action and earthquake pressure have hardened limestone in more recent strata, as in the case of the white marbles of carrara in italy, which are of the age of our oolites, that is, of the freestone of bath, etc., hardened by the heat of intruded volcanic rocks. but now: what is the limestone? and how did it get where it is--not into the mortar, i mean, but into the limestone quarry? let me tell you, or rather, help you to tell yourselves, by leading you, as before, from the known to the unknown. let me lead you to places unknown indeed to most; but there may be sailors or soldiers among my readers who know them far better than i do. let me lead you, in fancy, to some island in the tropic seas. after all, i am not leading you as far away as you fancy by several thousand miles, as you will see, i trust, ere i have done. let me take you to some island: what shall it be like? shall it be a high island, with cliff piled on cliff, and peak on peak, all rich with mighty forests, like a furred mantle of green velvet, mounting up and up till it is lost among white clouds above? or shall it be a mere low reef, which you do not see till you are close upon it; on which nothing rises above the water, but here and there a knot of cocoa-nut palms or a block of stone, or a few bushes, swarming with innumerable sea-fowl and their eggs? let it be which you will: both are strange enough; both beautiful; both will tell us a story. the ship will have to lie-to, and anchor if she can; it may be a mile, it may be only a few yards, from the land. for between it and the land will be a line of breakers, raging in before the warm trade- wind. and this, you will be told, marks the edge of the coral reef. you will have to go ashore in a boat, over a sea which looks unfathomable, and which may be a mile or more in depth, and search for an opening in the reef, through which the boat can pass without being knocked to pieces. you find one: and in a moment, what a change! the deep has suddenly become shallow; the blue white, from the gleam of the white coral at the bottom. but the coral is not all white, only indeed a little of it; for as you look down through the clear water, you find that the coral is starred with innumerable live flowers, blue, crimson, grey, every conceivable hue; and that these are the coral polypes, each with its ring of arms thrust out of its cell, who are building up their common habitations of lime. if you want to understand, by a rough but correct description, what a coral polype is: all who have been to the sea-side know, or at least have heard of, sea-anemones. now coral polypes are sea-anemones, which make each a shell of lime, growing with its growth. as for their shapes, the variety of them, the beauty of them, no tongue can describe them. if you want to see them, go to the coral rooms of the british or liverpool museums, and judge for yourselves. only remember that you must re-clothe each of those exquisite forms with a coating of live jelly of some delicate hue, and put back into every one of the thousand cells its living flower; and into the beds, or rather banks, of the salt-water flower garden, the gaudiest of shell-less sea-anemones, such as we have on our coasts, rooted in the cracks, and live shells and sea-slugs, as gaudy as they, crawling about, with fifty other forms of fantastic and exuberant life. you must not overlook, too, the fish, especially the parrot-fish, some of them of the gaudiest colours, who spend their lives in browsing on the live coral, with strong clipping and grinding teeth, just as a cow browses the grass, keeping the animal matter, and throwing away the lime in the form of an impalpable white mud, which fills up the interstices in the coral beds. the bottom, just outside the reef, is covered with that mud, mixed with more lime-mud, which the surge wears off the reef; and if you have, as you should have, a dredge on board, and try a haul of that mud as you row home, you may find, but not always, animal forms rooted in it, which will delight the soul of a scientific man. one, i hope, would be some sort of terebratula, or shell akin to it. you would probably think it a cockle: but you would be wrong. the animal which dwells in it has about the same relationship to a cockle as a dog has to a bird. it is a brachiopod; a family with which the ancient seas once swarmed, but which is rare now, all over the world, having been supplanted and driven out of the seas by newer and stronger forms of shelled animals. the nearest spot at which you are likely to dredge a live brachiopod will be in the deep water of loch fyne, in argyleshire, where two species still linger, fastened, strangely enough, to the smooth pebbles of a submerged glacier, formed in the open air during the age of ice, but sunk now to a depth of eighty fathoms. the first time i saw those shells come up in the dredge out of the dark and motionless abyss, i could sympathise with the feelings of mingled delight and awe which, so my companion told me, the great professor owen had in the same spot first beheld the same lingering remnants of a primaeval world. the other might be (but i cannot promise you even a chance of dredging that, unless you were off the coast of portugal, or the windward side of some of the west india islands) a live crinoid; an exquisite starfish, with long and branching arms, but rooted in the mud by a long stalk, and that stalk throwing out barren side branches; the whole a living plant of stone. you may see in museums specimens of this family, now so rare, all but extinct. and yet fifty or a hundred different forms of the same type swarmed in the ancient seas: whole masses of limestone are made up of little else but the fragments of such animals. but we have not landed yet on the dry part of the reef. let us make for it, taking care meanwhile that we do not get our feet cut by the coral, or stung as by nettles by the coral insects. we shall see that the dry land is made up entirely of coral, ground and broken by the waves, and hurled inland by the storm, sometimes in huge boulders, mostly as fine mud; and that, under the influence of the sun and of the rain, which filters through it, charged with lime from the rotting coral, the whole is setting, as cement sets, into rock. and what is this? a long bank of stone standing up as a low cliff, ten or twelve feet above high-water mark. it is full of fragments of shell, of fragments of coral, of all sorts of animal remains; and the lower part of it is quite hard rock. moreover, it is bedded in regular layers, just such as you see in a quarry. but how did it get there? it must have been formed at the sea-level, some of it, indeed, under the sea; for here are great masses of madrepore and limestone corals imbedded just as they grew. what lifted it up? your companions, if you have any who know the island, have no difficulty in telling you. it was hove up, they say, in the earthquake in such and such a year; and they will tell you, perhaps, that if you will go on shore to the main island which rises inside the reef, you may see dead coral beds just like these lying on the old rocks, and sloping up along the flanks of the mountains to several hundred feet above the sea. i have seen such many a time. thus you find the coral being converted gradually into a limestone rock, either fine and homogeneous, composed of coral grown into pulp, or filled with corals and shells, or with angular fragments of older coral rock. did you never see that last? no? yes, you have a hundred times. you have but to look at the marbles commonly used about these islands, with angular fragments imbedded in the mass, and here and there a shell, the whole cemented together by water holding in solution carbonate of lime, and there see the very same phenomenon perpetuated to this day. thus, i think, we have got first from the known to the unknown; from a tropic coral island back here to the limestone hills of great britain; and i did not speak at random when i said that i was not leading you away as far as you fancied by several thousand miles. examine any average limestone quarry from bristol to berwick, and you will see there all that i have been describing; that is, all of it which is not soft animal matter, certain to decay. you will see the lime-mud hardened into rock beds; you will see the shells embedded in it; you will see the corals in every stage of destruction; you will see whole layers made up of innumerable fragments of crinoids--no wonder they are innumerable, for, it has been calculated, there are in a single animal of some of the species , joints-- , bits of lime to fall apart when its soft parts decay. but is it not all there? and why should it not have got there by the same process by which similar old coral beds get up the mountain sides in the west indies and elsewhere; namely, by the upheaving force of earthquakes? when you see similar effects, you have a right to presume similar causes. if you see a man fall off a house here, and break his neck; and some years after, in london or new york, or anywhere else, find another man lying at the foot of another house, with his neck broken in the same way, is it not a very fair presumption that he has fallen off a house likewise? you may be wrong. he may have come to his end by a dozen other means: but you must have proof of that. you will have a full right, in science and in common sense, to say--that man fell off the house, till some one proves to you that he did not. in fact, there is nothing which you see in the limestones of these isles--save and except the difference in every shell and coral--which you would not see in the coral-beds of the west indies, if such earthquakes as that famous one at st. thomas's, in , became common and periodic, upheaving the land (they needs upheave it a very little, only two hundred and fifty feet), till st. thomas's, and all the virgin isles, and the mighty mountain of porto rico, which looms up dim and purple to the west, were all joined into dry land once more, and the lonely coral-shoal of anegada were raised, as it would be raised then, into a limestone table-land, like that of central ireland, of galway, or of county clare. but you must clearly understand, that however much these coralline limestones have been upheaved since they were formed, yet the sea- bottom, while they were being formed, was sinking and not rising. this is a fact which was first pointed out by mr. darwin, from the observations which he made in the world-famous voyage of the beagle; and the observations of subsequent great naturalists have all gone to corroborate his theory. it was supposed at first, you must understand, that when a coral island rose steeply to the surface of the sea out of blue water, perhaps a thousand fathoms or more, that fact was plain proof that the little coral polypes had begun at the bottom of the sea, and, in the course of ages, built up the whole island an enormous depth. but it soon came out that that theory was not correct; for the coral polypes cannot live and build save in shallow water--say in thirty to forty fathoms. indeed, some of the strongest and largest species work best at the very surface, and in the cut of the fiercest surf. and so arose a puzzle as to how coral rock is often found of vast thickness, which mr. darwin explained. his theory was, and there is no doubt now that it is correct, that in these cases the sea-bottom is sinking; that as it sinks, carrying the coral beds down with it, the coral dies, and a fresh live crop of polypes builds on the top of the houses of their dead ancestors: so that, as the depression goes on, generation after generation builds upwards, the living on the dead, keeping the upper surface of the reef at the same level, while its base is sinking downward into the abyss. applying this theory to the coral reef of the pacific ocean, the following interesting facts were made out: that where you find an island rising out of deep water, with a ring of coral round it, a little way from the shore--or, as in eastern australia, a coast with a fringing reef (the flinders reef of australia is eleven thousand miles long)--that is a pretty sure sign that that shore, or mountain, is sinking slowly beneath the sea. that where you find, as you often do in the pacific, a mere atoll, or circular reef of coral, with a shallow pond of smooth water in the centre, and deep sea round, that is a pretty sure sign that the mountain-top has sunk completely into the sea, and that the corals are going on building where its peak once was. and more. on working out the geography of the south sea islands by the light of this theory of mr. darwin's, the following extraordinary fact has been discovered: that over a great part of the pacific ocean sinking is going on, and has been going on for ages; and that the greater number of the beautiful and precious south sea islands are only the remnants of a vast continent or archipelago, which once stretched for thousands of miles between australia and south america. now, applying the same theory to limestone beds, which are, as you know, only fossil coral reefs, we have a right to say, when we see in england, scotland, ireland, limestones several thousand feet thick, that while they were being laid down as coral reef, the sea-bottom, and probably the neighbouring land, must have been sinking to the amount of their thickness--to several thousand feet--before that later sinking which enabled several hundred feet of millstone grit to be laid down on the top of the limestone. this millstone grit is a new and a very remarkable element in our strange story. from derby to northumberland it forms vast and lofty moors, capping, as at whernside and penygent, the highest limestone hills with its hard, rough, barren, and unfossiliferous strata. wherever it is found, it lies on the top of the "mountain," or carboniferous limestone. almost everywhere, where coal is found in england, it lies on the millstone grit. i speak roughly, for fear of confusing my readers with details. the three deposits pass more or less, in many places, into each other: but always in the order of mountain limestone below, millstone grit on it, and coal on that again. now what does its presence prove? what but this? that after the great coral reefs which spread over somersetshire and south wales, around the present estuary of the severn,--and those, once perhaps joined to them, which spread from derby to berwick, with a western branch through north-east wales,--were laid down--after all this, i say, some change took place in the sea-bottom, and brought down on the reefs of coral sheets of sand, which killed the corals and buried them in grit. does any reader wish for proof of this? let him examine the "cherty," or flinty, beds which so often appear where the bottom of the millstone grit is passing into the top of the mountain limestone--the beds, to give an instance, which are now quarried on the top of the halkin mountain in flintshire, for chert, which is sent to staffordshire to be ground down for the manufacture of china. he will find layers in those beds, of several feet in thickness, as hard as flint, but as porous as sponge. on examining their cavities he will find them to be simply hollow casts of innumerable joints of crinoids, so exquisitely preserved, even to their most delicate markings, that it is plain they were never washed about upon a beach, but have grown where, or nearly where, they lie. what then, has happened to them? they have been killed by the sand. the soft parts of the animals have decayed, letting the , joints (more or less) belonging to each animal fall into a heap, and be imbedded in the growing sand-rock; and then, it may be long years after, water filtering through the porous sand has removed the lime of which the joints were made, and left their perfect casts behind. so much for the millstone grits. how long the deposition of sand went on, how long after it that second deposition of sands took place, which goes by the name of the "gannister," or lower coal- measures, we cannot tell. but it is clear, at least, that parts of that ancient sea were filling up and becoming dry land. for coal, or fossilised vegetable matter, becomes more and more common as we ascend in the series of beds; till at last, in the upper coal- measures, the enormous wealth of vegetation which grew, much of it, where it is now found, prove the existence of some such sheets of fertile and forest-clad lowland as i described in my last paper. thousands of feet of rich coral reef; thousands of feet of barren sands; then thousands of feet of rich alluvial forest--and all these sliding into each other, if not in one place, then in another, without violent break or change; this is the story which the lime in the mortar and the coal on the fire, between the two, reveal. vi. the slates on the roof the slates on the roof should be, when rightly understood, a pleasant subject for contemplation to the dweller in a town. i do not ask him to imitate the boy who, cliff-bred from his youth, used to spend stolen hours on the house-top, with his back against a chimney-stalk, transfiguring in his imagination the roof-slopes into mountain-sides, the slates into sheets of rock, the cats into lions, and the sparrows into eagles. i only wish that he should--at least after reading this paper--let the slates on the roof carry him back in fancy to the mountains whence they came; perhaps to pleasant trips to the lakes and hills of cumberland, westmoreland, and north wales; and to recognise--as he will do if he have intellect as well as fancy--how beautiful and how curious an object is a common slate. beautiful, not only for the compactness and delicacy of its texture, and for the regularity and smoothness of its surface, but still more for its colour. whether merely warm grey, as when dry, or bright purple, as when wet, the colour of the english slate well justifies mr. ruskin's saying, that wherever there is a brick wall and a slate roof there need be no want of rich colour in an english landscape. but most beautiful is the hue of slate, when, shining wet in the sunshine after a summer shower, its blue is brought out in rich contrast by golden spots of circular lichen, whose spores, i presume, have travelled with it off its native mountains. then, indeed, it reminds the voyager of a sight which it almost rivals in brilliancy-- of the sapphire of the deep ocean, brought out into blazing intensity by the contrast of the golden patches of floating gulf-weed beneath the tropic sun. beautiful, i say, is the slate; and curious likewise, nay, venerable; a most ancient and elaborate work of god, which has lasted long enough, and endured enough likewise, to bring out in it whatsoever latent capabilities of strength and usefulness might lie hid in it; which has literally been--as far as such words can apply to a thing inanimate-- heated hot with burning fears, and bathed in baths of hissing tears, and battered by the strokes of doom to shape and use. and yet it was at first naught but an ugly lump of soft and shapeless ooze. therefore, the slates to me are as a parable, on which i will not enlarge, but will leave each reader to interpret it for himself. i shall confine myself now to proofs that slate is hardened mud, and to hints as to how it assumed its present form. that slate may have been once mud, is made probable by the simple fact that it can be turned into mud again. if you grind tip slate, and then analyse it, you will find its mineral constituents to be exactly those of a fine, rich, and tenacious clay. the slate districts (at least in snowdon) carry such a rich clay on them, wherever it is not masked by the ruins of other rocks. at ilfracombe, in north devon, the passage from slate below to clay above, may be clearly seen. wherever the top of the slate beds, and the soil upon it, is laid bare, the black layers of slate may be seen gradually melting--if i may use the word--under the influence of rain and frost, into a rich tenacious clay, which is now not black, like its parent slate, but red, from the oxidation of the iron which it contains. but, granting this, how did the first change take place? it must be allowed, at starting, that time enough has elapsed, and events enough have happened, since our supposed mud began first to become slate, to allow of many and strange transformations. for these slates are found in the oldest beds of rocks, save one series, in the known world; and it is notorious that the older and lower the beds in which the slates are found, the better, that is, the more perfectly elaborate, is the slate. the best slates of snowdon--i must confine myself to the district which i know personally--are found in the so-called "cambrian" beds. below these beds but one series of beds is as yet known in the world, called the "laurentian." they occur, to a thickness of some eighty thousand feet, in labrador, canada, and the adirondack mountains of new york: but their representatives in europe are, as far as is known only to be found in the north-west highlands of scotland, and in the island of lewis, which consists entirely of them. and it is to be remembered, as a proof of their inconceivable antiquity, that they have been upheaved and shifted long before the cambrian rocks were laid down "unconformably" on their worn and broken edges. above the "cambrian" slates--whether the lower and older ones of penrhyn and llanberris, which are the same--one slate mountain being worked at both sides in two opposite valleys--or the upper and newer slates of tremadoc, lie other and newer slate-bearing beds of inferior quality, and belonging to a yet newer world, the "silurian." to them belong the llandeilo flags and slates of wales, and the skiddaw slates of cumberland, amid beds abounding in extinct fossil forms. fossil shells are found, it is true, in the upper cambrian beds. in the lower they have all but disappeared. whether their traces have been obliterated by heat and pressure, and chemical action, during long ages; or whether, in these lower beds, we are actually reaching that "primordial zone" conceived of by m. barrande, namely, rocks which existed before living things had begun to people this planet, is a question not yet answered. i believe the former theory to be the true one. that there was life, in the sea at least, even before the oldest cambrian rocks were laid down, is proved by the discovery of the now famous fossil, the eozoon, in the laurentian limestones, which seems to have grown layer after layer, and to have formed reefs of limestone as do the living coral-building polypes. we know no more as yet. but all that we do know points downwards, downwards still, warning us that we must dig deeper than we have dug as yet, before we reach the graves of the first living things. let this suffice at present for the cambrian and laurentian rocks. the silurian rocks, lower and upper, which in these islands have their chief development in wales, and which are nearly thirty-eight thousand feet thick; and the devonian or old red sandstone beds, which in the fans of brecon and carmarthenshire attain a thickness of ten thousand feet, must be passed through in an upward direction before we reach the bottom of that carboniferous limestone of which i spoke in my last paper. we thus find on the cambrian rocks forty- five thousand feet at least of newer rocks, in several cases lying unconformably on each other, showing thereby that the lower beds had been upheaved, and their edges worn off on a sea-shore, ere the upper were laid down on them; and throughout this vast thickness of rocks, the remains of hundreds of forms of animals, corals, shells, fish, older forms dying out in the newer rocks, and new ones taking their places in a steady succession of ever-varying forms, till those in the upper beds have become unlike those in the lower, and all are from the beginning more or less unlike any existing now on earth. whole families, indeed, disappear entirely, like the trilobites, which seem to have swarmed in the silurian seas, holding the same place there as crabs and shrimps do in our modern seas. they vanish after the period of the coal, and their place is taken by an allied family of crustaceans, of which only one form (as far as i am aware) lingers now on earth, namely, the "king crab," or limulus, of the indian seas, a well-known animal, of which specimens may sometimes be seen alive in english aquaria. so perished in the lapse of those same ages, the armour-plated or "ganoid" fish which hugh miller made so justly famous--and which made him so justly famous in return-- appearing first in the upper silurian beds, and abounding in vast variety of strange forms in the old red sandstone, but gradually disappearing from the waters of the world, till their only representatives, as far as known, are the lepidostei, or "bony pikes," of north america; the polypteri of the nile and senegal; the lepidosirens of the african lakes and western rivers; the ceratodus or barramundi of queensland (the two latter of which approach amphibians), and one or two more fantastic forms, either rudimentary or degraded, which have lasted on here and there in isolated stations through long ages, comparatively unchanged while all the world is changed around them, and their own kindred, buried like the fossil ceratodus of the trias beneath thousands of feet of ancient rock, among creatures the likes whereof are not to be found now on earth. and these are but two examples out of hundreds of the vast changes which have taken place in the animal life of the globe, between the laying down of the cambrian slates and the present time. surely--and it is to this conclusion i have been tending throughout a seemingly wandering paragraph--surely there has been time enough during all those ages for clay to change into slate. and how were they changed? i think i cannot teach my readers this more simply than by asking them first to buy sheet no. lxxviii. s.e. (bangor) of the snowdon district of the government geological survey, which may be ordered at any good stationer's, price s.; and study it with me. he will see down the right-hand margin interpretations of the different colours which mark the different beds, beginning with the youngest (alluvium) atop, and going down through carboniferous limestone and sandstone, upper silurian, lower silurian, cambrian, and below them certain rocks marked of different shades of red, which signify rocks either altered by heat, or poured out of old volcanic vents. he will next see that the map is covered with a labyrinth of red patches and curved lines, signifying the outcrop or appearance at the surface of these volcanic beds. they lie at every conceivable slope; and the hills and valleys have been scooped out by rain and ice into every conceivable slope likewise. wherefore we see, here a broad patch of red, where the back of a sheet of lava, porphyry, greenstone, or what not is exposed; there a narrow line curving often with the curve of the hill-side, where only the edge of a similar sheet is exposed; and every possible variety of shape and attitude between these two. he will see also large spaces covered with little coloured dots, which signify (as he will find at the margin) beds of volcanic ash. if he look below the little coloured squares on the margin, he will see figures marking the strike, or direction of the inclination of the beds--inclined, vertical, horizontal, contorted; that the white lines in the map signify faults, i.e. shifts in the strata; the gold lines, lodes of metal--the latter of which i should advise him strongly, in this district at least, not to meddle with: but to button up his pockets, and to put into the fire, in wholesome fear of his own weakness and ignorance, any puffs of mining companies which may be sent him--as one or two have probably been sent him already. furnished with which keys to the map, let him begin to con it over, sure that there is if not an order, still a grand meaning in all its seeming confusion; and let him, if he be a courteous and grateful person, return due thanks to professor ramsay for having found it all out; not without wondering, as i have often wondered, how even professor ramsay's acuteness and industry could find it all out. when my reader has studied awhile the confusion--for it is a true confusion--of the different beds, he will ask, or at least have a right to ask, what known process of nature can have produced it? how have these various volcanic rocks, which he sees marked as felspathic traps, quartz porphyries, greenstones, and so forth, got intermingled with beds which he is told to believe are volcanic ashes, and those again with fossil-bearing silurian beds and cambrian slates, which he is told to believe were deposited under water? and his puzzle will not be lessened when he is told that, in some cases, as in that of the summit of snowdon, these very volcanic ashes contain fossil shells. the best answer i can give is to ask him to use his imagination, or his common sense; and to picture to himself what must go on in the case of a submarine eruption, such as broke out off the coast of iceland in and , off the azores in , and in our day in more than one spot in the pacific ocean. a main bore or vent--or more than one--opens itself between the bottom of the sea and the nether fires. from each rushes an enormous jet of high-pressure steam and other gases, which boils up through the sea, and forms a cloud above; that cloud descends again in heavy rain, and gives out often true lightning from its under side. but it does more. it acts as a true steam-gun, hurling into the air fragments of cold rock rasped off from the sides of the bore, and fragments also of melted lava, and clouds of dust, which fall again into the sea, and form there beds either of fine mud or of breccia-- that is, fragments of stone embedded in paste. this, the reader will understand, is no fancy sketch, as far as i am concerned. i have steamed into craters sawn through by the sea, and showing sections of beds of ash dipping outwards and under the sea, and in them boulders and pebbles of every size, which had been hurled out of the crater; and in them also veins of hardened lava, which had burrowed out through the soft ashes of the cone. of those lava veins i will speak presently. what i want the reader to think of now is the immense quantity of ash which the steam-mitrailleuse hurls to so vast a height into the air, that it is often drifted many miles down to leeward. to give two instances: the jet of steam from vesuvius, in the eruption of , rose more than four miles into the air; the jet from the souffriere of st. vincent in the west indies, in , probably rose higher; certainly it met the n.e. trade-wind, for it poured down a layer of ashes, several inches thick, not only on st. vincent itself, but on barbadoes, eighty miles to windward, and therefore on all the sea between. now let us consider what that represents--a layer of fine mud, laid down at the bottom of the ocean, several inches thick, eighty miles at least long, and twenty miles perhaps broad, by a single eruption. suppose that hardened in long ages (as it would be under pressure) into a bed of fine grained felstone, or volcanic ash; and we can understand how the ash-beds of snowdonia--which may be traced some of them for many square miles-- were laid down at the bottom of an ancient sea. but now about the lavas or true volcanic rocks, which are painted (as is usual in geological maps) red. let us go down to the bottom of the sea, and build up our volcano towards the surface. first, as i said, the subterranean steam would blast a bore. the dust and stones, rasped and blasted out of that hole would be spread about the sea-bottom as an ash-bed sloping away round the hole; then the molten lava would rise in the bore, and flow out over the ashes and the sea-bottom--perhaps in one direction, perhaps all round. then, usually, the volcano, having vented itself, would be quieter for a time, till the heat accumulated below, and more ash was blasted out, making a second ash-bed; and then would follow a second lava flow. thus are produced the alternate beds of lava and ash which are so common. now suppose that at this point the volcano was exhausted, and lay quiet for a few hundred years, or more. if there was any land near, from which mud and sand were washed down, we might have layers on layers of sediment deposited, with live shells, etc., living in them, which would be converted into fossils when they died; and so we should have fossiliferous beds over the ashes and lavas. indeed, shells might live and thrive in the ash-mud itself, when it cooled, and the sea grew quiet, as they have lived and thriven in snowdonia. now suppose that after these sedimentary beds are laid down by water, the volcano breaks out again--what would happen? many things: specially this, which has often happened already. the lava, kept down by the weight of these new rocks, searches for the point of least resistance, and finds it in a more horizontal direction. it burrows out through the softer ash-beds, and between the sedimentary beds, spreading itself along horizontally. this process accounts for the very puzzling, though very common case in snowdon and elsewhere, in which we find lavas interstratified with rocks which are plainly older than those lavas. perhaps when that is done the volcano has got rid of all its lava, and is quiet. but if not, sooner or later, it bores up through the new sedimentary rocks, faulting them by earthquake shocks till it gets free vent, and begins its layers of alternate ash and lava once more. and consider this fact also: if near the first (as often happens) there is another volcano, the lava from one may run over the lava from the other, and we may have two lavas of different materials overlying each other, which have come from different directions. the ashes blown out of the two craters may mingle also, and so, in the course of ages, the result may be such a confusion of ashes, lavas, and sedimentary rocks as we find throughout most mountain ranges in snowdon, in the lake mountains, in the auvergne in france, in sicily round etna, in italy round vesuvius, and in so many west indian islands; the last confusion of which is very likely to be this: that when the volcano has succeeded--as it did in the case of sabrina island off the azores in , and as it did, perhaps often, in snowdonia--in piling up an ash cone some hundred feet out of the sea; that--as has happened to sabrina island--the cone is sunk again by earthquakes, and gnawn down at the same time by the sea-waves, till nothing is left but a shoal under water. but where have all its vast heaps of ashes gone? to be spread about over the bottom of the sea, to mingle with the mud already there, and so make beds of which, like many in snowdon, we cannot say whether they are of volcanic or of marine origin, because they are of both. but what has all this to do with the slates? i shall not be surprised if my readers ask that question two or three times during this paper. but they must be kind enough to let me tell my story my own way. the slates were not made in a day, and i fear they cannot be explained in an hour: unless we begin carefully at the beginning in order to end at the end. let me first make my readers clearly understand that all our slate-bearing mountains, and most also of the non-slate-bearing ones likewise, are formed after the fashion which i have described, namely, beneath the sea. i do not say that there may not have been, again, and again, ash-cones rising above the surface of the waves. but if so, they were washed away, again and again, ages before the land assumed anything of its present shape; ages before the beds were twisted and upheaved as they are now. and therefore i beg my readers to put out of their minds once and for all the fancy that in any known part of these islands craters are to be still seen, such as exist in etna, or vesuvius, or other volcanoes now at work in the open air. it is necessary to insist on this, because many people hearing that certain mountains are volcanic, conclude--and very naturally and harmlessly--that the circular lakes about their tops are true craters. i have been told, for instance, that that wonderful little blue glas llyn, under the highest cliff of snowdon, is the old crater of the mountain; and i have heard people insist that a similar lake, of almost equal grandeur, in the south side of cader idris, is a crater likewise. but the fact is not so. any one acquainted with recent craters would see at once that glas llyn is not an ancient one; and i am not surprised to find the government geologists declaring that the llyn on cader idris is not one either. the fact is, that the crater, or rather the place where the crater has been, in ancient volcanoes of this kind, is probably now covered by one of the innumerable bosses of lava. for, as an eruption ceases, the melted lava cools in the vents, and hardens; usually into lava infinitely harder than the ash-cone round it; and this, when the ash-cone is washed off, remains as the highest part of the hill, as in the mont dore and the cantal in france, and in several extinct volcanoes in the antilles. of course the lava must have been poured out, and the ashes blown out from some vents or other, connected with the nether world of fire; probably from many successive vents. for in volcanoes, when one vent is choked, another is wont to open at some fresh point of least resistance among the overlying rocks. but where are these vents? buried deep under successive eruptions, shifted probably from their places by successive upheavings and dislocations; and if we wanted to find them we should have to quarry the mountain range all over, a mile deep, before we hit upon here and there a tap-root of ancient lava, connecting the upper and the nether worlds. there are such tap- roots, probably, under each of our british mountain ranges. but snowdon, certainly, does not owe its shape to the fact of one of these old fire vents being under it. it owes its shape simply to the accident of some of the beds toward the summit being especially hard, and thus able to stand the wear and tear of sea-wave, ice, and rain. its lakes have been formed quite regardless of the lie of the rocks, though not regardless of their relative hardness. but what forces scooped them out--whether they were originally holes left in the ground by earthquakes, and deepened since by rain and rivers, or whether they were scooped out by ice, or by any other means, is a question on which the best geologists are yet undecided--decided only on this--that craters they are not. as for the enormous changes which have taken place in the outline of the whole of the mountains, since first their strata were laid down at the bottom of the sea: i shall give facts enough, before this paper is done, to enable readers to judge of them for themselves. the reader will now ask, naturally enough, how such a heap of beds as i have described can take the shape of mountains like snowdon. look at any sea cliff in which the strata are twisted and set on slope. there are hundreds of such in these isles. the beds must have been at one time straight and horizontal. but it is equally clear that they have been folded by being squeezed laterally. at least, that is the simplest explanation, as may be proved by experiment. take a number of pieces of cloth, or any such stuff; lay them on each other and then squeeze them together at each end. they will arrange themselves in folds, just as the beds of the cliff have done. and if, instead of cloth, you take some more brittle matter, you will find that, as you squeeze on, these folds will tend to snap at the points of greatest tension or stretching, which will be of course at the anticlinal and synclinal lines--in plain english, the tops and bottoms of the folds. thus cracks will be formed; and if the pressure goes on, the ends of the layers will shift against each other in the line of those cracks, forming faults like those so common in rocks. but again, suppose that instead of squeezing these broken and folded lines together any more, you took off the pressure right and left, and pressed them upwards from below, by a mimic earthquake. they would rise; and as they rose leave open space between them. now if you could contrive to squeeze into them from below a paste, which would harden in the cracks and between the layers, and so keep them permanently apart, you would make them into a fair likeness of an average mountain range--a mess--if i may make use of a plain old word--of rocks which have, by alternate contraction and expansion, helped in the latter case by the injection of molten lava, been thrust about as they are in most mountain ranges. that such a contraction and expansion goes on in the crust of the earth is evident; for here are the palpable effects of it. and the simplest general cause which i can give for it is this: that things expand as they are heated, and contract as they are cooled. now i am not learned enough--and were i, i have not time--to enter into the various theories which philosophers have put forward, to account for these grand phenomena. the most remarkable, perhaps, and the most probable, is the theory of m. elie de beaumont, which is, in a few words, this: that this earth, like all the planets, must have been once in a state of intense heat throughout, as its mass inside is probably now. that it must be cooling, and giving off its heat into space. that, therefore, as it cools, its crust must contract. that, therefore, in contracting, wrinkles (for the loftiest mountain chains are nothing but tiny wrinkles, compared with the whole mass of the earth), wrinkles, i say, must form on its surface from time to time. and that the mountain chains are these wrinkles. be that as it may, we may safely say this. that wherever the internal heat of the earth tends (as in the case of volcanoes) towards a particular spot, that spot must expand, and swell up, bulging the rocks out, and probably cracking them, and inserting melting lava into those cracks from below. on the other hand, if the internal heat leaves that spot again, and it cools, then it must contract more or less, in falling inward toward the centre of the earth; and so the beds must be crumpled, and crushed, and shifted against each other still more, as those of our mountains have been. but here may arise, in some of my readers' minds, a reasonable question--if these upheaved beds were once horizontal, should we not be likely to find them, in some places, horizontal still? a reasonable question, and one which admits of a full answer. they know, of course, that there has been a gradual, but steady, change in the animals of this planet; and that the relative age of beds can, on the strength of that known change, be determined generally by the fossils, usually shells, peculiar to them: so that if we find the same fashion of shells, and still more the same species of shells, in two beds in different quarters of the world, then we have a right to say--these beds were laid down at least about the same time. that is a general rule among all geologists, and not to be gainsaid. now i think i may say, that, granting that we can recognise a bed by its fossils, there are few or no beds which are found in one place upheaved, broken, and altered by heat, which are not found in some other place still horizontal, unbroken, unaltered, and more or less as they were at first. from the most recent beds; from the upheaved coral-rocks of the west indies, and the upheaved and faulted boulder clay and chalk of the isle of moen in denmark--downwards through all the strata, down to that very ancient one in which the best slates are found, this rule, i believe, stands true. it stands true, certainly, of the ancient silurian rocks of wales, cumberland, ireland, and scotland. for, throughout great tracts of russia, and in parts of norway and sweden, sir roderick murchison discovered our own silurian beds, recognisable from their peculiar fossils. but in what state? not contracted, upheaved, and hardened to slates and grits, as they are in wales and elsewhere: but horizontal, unbroken, and still soft, because undisturbed by volcanic rooks and earthquakes. at the bottom of them all, near petersburg, sir roderick found a shale of dried mud (to quote his own words), "so soft and incoherent that it is even used by sculptors for modelling, although it underlies the great mass of fossil-bearing silurian rocks, and is, therefore, of the same age as the lower crystalline hard slates of north wales. so entirely have most of these eldest rocks in russia been exempted from the influence of change, throughout those enormous periods which have passed away since their accumulation." among the many discoveries which science owes to that illustrious veteran, i know none more valuable for its bearing on the whole question of the making of the earth-crust, than this one magnificent fact. but what a contrast between these scandinavian and russian rocks and those of britain! never exceeding, in scandinavia, a thousand feet in thickness, and lying usually horizontal, as they were first laid down, they are swelled in britain to a thickness of thirty thousand feet, by intruded lavas and ashes; snapt, turned, set on end at every conceivable angle; shifted against each other to such an extent, that, to give a single instance, in the vale of gwynnant, under snowdon, an immense wedge of porphyry has been thrust up, in what is now the bottom of the valley, between rocks far newer than it, on one side to a height of eight hundred, on the other to a height of eighteen hundred feet--half the present height of snowdon. nay, the very slate beds of snowdonia have not forced their way up from under the mountain--without long and fearful struggles. they are set in places upright on end, then horizontal again, then sunk in an opposite direction, then curled like sea-waves, then set nearly upright once more, and faulted through and through, six times, i believe, in the distance of a mile or two; they carry here and there on their backs patches of newer beds, the rest of which has long vanished; and in their rise they have hurled back to the eastward, and set upright, what is now the whole western flank of snowdon, a mass of rock which was then several times as thick as it is now. the force which thus tortured them was probably exerted by the great mass of volcanic quartz-porphyry, which rises from under them to the north-west, crossing the end of the lower lake of the llanberris; and indeed the shifts and convulsions which have taken place between them and the menai straits are so vast that they can only be estimated by looking at them on the section which may be found at the end of professor ramsay's "geological survey of north wales." but anyone who will study that section, and use (as with the map) a little imagination and common sense, will see that between the heat of that porphyry, which must have been poured out as a fluid mass as hot, probably, as melted iron, and the pressure of it below, and of the silurian beds above, the cambrian mud-strata of llanberris and penrhyn quarries must have suffered enough to change them into something very different from mud, and, therefore, probably, into what they are now--namely, slate. and now, at last, we have got to the slates on the roof, and may disport ourselves over them--like the cats. look at any piece of slate. all know that slate splits or cleaves freely, in one direction only, into flat layers. now any one would suppose at first sight, and fairly enough, that the flat surface--the "plane of cleavage"--was also the plane of bedding. in simpler english we should say--the mud which has hardened into the slate was laid down horizontally; and therefore each slate is one of the little horizontal beds of it, perhaps just what was laid down in a single tide. we should have a right to do so, because that would be true of most sedimentary rocks. but it would not be true of slate. the plane of bedding in slate has nothing to do with the plane of cleavage. or, more plainly, the mud of which the slate is made may have been deposited at the sea-bottom at any angle to the plane of cleavage. we may sometimes see the lines of the true bedding--the lines which were actually horizontal when the mud was laid down--in bits of slate, and find them sometimes perpendicular to, sometimes inclined to, and sometimes again coinciding with the plane of cleavage, which they have evidently acquired long after. nay, more. these parallel planes of cleavage, at each of which the slate splits freely, will run through a whole mountain at the same angle, though the beds through which they run may be tilted at different angles, and twisted into curves. now what has made this change in the rook? we do not exactly know. one thing is clear, that the particles of the now solid rock have actually moved on themselves. and this is proved by a very curious fact--which the reader, if he geologises about slate quarries much, may see with his own eyes. the fossils in the slate are often distorted into quaint shapes, pulled out long if they lie along the plane of cleavage, or squeezed together, or doubled down on both sides, if they lie across the plane. so that some force has been at work which could actually change the shape of hard shells, very slowly, no doubt, else it would have snapped and crumbled them. if i am asked what that force was, i do not know. i should advise young geologists to read what sir henry de la beche has said on it in his admirable "geological observer," pp. - . he will find there, too, some remarks on that equally mysterious phenomena of jointing, which you may see in almost all the older rocks; it is common in limestones. all we can say is, that some force has gone on, or may be even now going on, in the more ancient rocks, which is similar to that which produces single crystals; and similar, too, to that which produced the jointed crystals of basalt, i.e. lava, at the giant's causeway, in ireland, and staffa, in the hebrides. two philosophers--mr. robert were fox and mr. robert hunt--are of opinion that the force which has determined the cleavage of slates may be that of the electric currents, which (as is well known) run through the crust of the earth. mr. sharpe, i believe, attributes the cleavage to the mere mechanical pressure of enormous weights of rock, especially where crushed by earthquakes. professor rogers, again, points out that as these slates may have been highly heated, thermal electricity (i.e. electricity brought out by heat) may have acted on them. one thing at least is clear. that the best slates are found among ancient lavas, and also in rocks which are faulted and tilted enormously, all which could not have happened without a proportionately enormous pressure, and therefore heat; and next, that the best slates are invariably found in the oldest beds--that is, in the beds which have had most time to endure the changes, whether mechanical or chemical, which have made the earth's surface what we see it now. another startling fact the section of snowdonia, and i believe of most mountain chains in these islands, would prove--namely, that the contour of the earth's surface, as we see it now, depends very little, certainly in mountains composed of these elder rocks upon the lie of the strata, or beds, but has been carved out by great forces, long after those beds were not only laid down and hardened, but faulted and tilted on end. snowdon itself is so remarkable an instance of this fact that, as it is a mountain which every one in these happy days of excursion-trains and steamers either has seen or can see, i must say a few more words about it. any one who saw that noble peak leaping high into the air, dominating all the country round, at least upon three sides, and was told that its summit consisted of beds much newer, not much older, than the slate-beds fifteen hundred feet down on its north-western flank--any one, i say, would have the right at first sight, on hearing of earthquake faults and upheavals, to say--the peak of snowdon has been upheaved to its present height above and out of the lower lands around. but when he came to examine sections, he would find his reasonable guess utterly wrong. snowdon is no swelling up of the earth's crust. the beds do not, as they would in that case, slope up to it. they slope up from it, to the north-west in one direction, and the south-south-west in the other; and snowdon is a mere insignificant boss, left hanging on one slope of what was once an enormous trough, or valley, of strata far older than itself. by restoring these strata, in the direction of the angles, in which they crop out, and vanish at the surface, it is found that to the north- west--the direction of the menai straits--they must once have risen to a height of at least six or seven thousand feet; and more, by restoring them, specially the ash-bed of snowdon, towards the south- east--which can be done by the guidance of certain patches of it left on other hills--it is found that south of ffestiniog, where the cambrian rocks rise again to the surface, the south side of the trough must have sloped upwards to a height of from fifteen to twenty thousand feet, whether at the bottom of the sea, or in the upper air, we cannot tell. but the fact is certain, that off the surface of wales, south of ffestiniog a mass of solid rock as high as the andes has been worn down and carried bodily away; and that a few miles south again, the peak of arran mowddy, which is now not two thousand feet high, was once--either under the sea or above it--nearer ten thousand feet. if i am asked whither is all that enormous mass of rock--millions of tons--gone? where is it now? i know not. but if i dared to hazard a guess, i should say it went to make the new red sandstones of england. the new red sandstones must have come from somewhere. the most likely region for them to have come from is from north wales, where, as we know, vast masses of gritty rock have been ground off, such as would make fine sandstones if they had the chance. so that many a grain of sand in chester walls was probably once blasted out of the bowels of the earth into the old silurian sea, and after a few hundreds of thousands of years' repose in a snowdonian ash-bed, was sent eastward to build the good old city and many a good town more. and the red marl--the great deposit of red marl which covers a wide region of england--why should not it have come from the same quarter? why should it not be simply the remains of the snowdon slate? mud the slate was, and into mud it has returned. why not? some of the richest red marl land i know, is, as i have said, actually being made now, out of the black slates of ilfracombe, wherever they are weathered by rain and air. the chemical composition is the same. the difference in colour between black slate and red marl is caused simply by the oxidation of the iron in the slate. and if my readers want a probable cause why the sandstones lie undermost, and the red marl uppermost--can they not find one for themselves? i do not say that it is the cause, but it is at least a causa vera, one which would fully explain the fact, though it may be explicable in other ways. think, then, or shall i think for my readers? then do they not see that when the welsh mountains were ground down, the silurian strata, being uppermost, would be ground down first, and would go to make the lower strata of the great new red sandstone lowland; and that being sandy, they would make the sandstones? but wherever they were ground through, the lower cambrian slates would be laid bare; and their remains, being washed away by the sea the last, would be washed on to the top of the remains of the silurians; and so (as in most cases) the remains of the older rock, when redeposited by water, would lie on the remains of the younger rock. and do they not see that (if what i just said is true) these slates would grind up into red marl, such as is seen over the west and south of cheshire and staffordshire and far away into nottinghamshire? the red marl must almost certainly have been black slate somewhere, somewhen. why should it not have been such in snowdon? and why should not the slates in the roof be the remnants of the very beds which are now the marl in the fields? and thus i end my story of the slates in the roof, and these papers on town geology. i do so, well knowing how imperfect they are: though not, i believe, inaccurate. they are, after all, merely suggestive of the great amount that there is to be learnt about the face of the earth and how it got made, even by the townsman, who can escape into the country and exchange the world of man for the world of god, only, perhaps, on sundays--if, alas! even then--or only once a year by a trip in a steamer or an excursion train. little, indeed, can he learn of the planet on which he lives. little in that direction is given to him, and of him little shall be required. but to him, for that very reason, all that can be given should be given; he should have every facility for learning what he can about this earth, its composition, its capabilities; lest his intellect, crushed and fettered by that artificial drudgery which we for a time miscall civilisation, should begin to fancy, as too many do already, that the world is composed mainly of bricks and deal, and governed by acts of parliament. if i shall have awakened any townsmen here and there to think seriously of the complexity, the antiquity, the grandeur, the true poetry, of the commonest objects around them, even the stones beneath their feet; if i shall have suggested to them the solemn thought that all these things, and they themselves still more, are ordered by laws, utterly independent of man's will about them, man's belief in them; if i shall at all have helped to open their eyes that they may see, and their ears that they may hear, the great book which is free to all alike, to peasant as to peer, to men of business as to men of science, even that great book of nature, which is, as lord bacon said of old, the word of god revealed in facts--then i shall have a fresh reason for loving that science of geology, which has been my favourite study since i was a boy. footnotes: { } see "nature," no. xxv. (macmillan & co.) { } these lectures were delivered to the members of the natural science class at chester in . { } see a most charming paper on "the physics of arctic ice," by dr. robert brown of campster, published in the quarterly journal of the geological society, june, . this article is so remarkable, not only for its sound scientific matter, but for the vividness and poetic beauty of its descriptions, that i must express a hope that the learned author will some day enlarge it, and publish it in a separate form. { } see lyell, "antiquity of man," p. et seq. [illustration: slab with fossil impressions] remarks on some fossil impressions in the sandstone rocks of connecticut river. by john c. warren, m.d. president of the boston society of natural history. [illustration: logo] boston: ticknor and fields, , washington street. . boston: printed by john wilson and son, , school street. the principal part of these remarks were made at the meetings of the boston society of natural history. a portion of them also have been printed in the proceedings of the society. the object of this publication is to afford to those who are not members of the society an opportunity of obtaining some knowledge of fossil impressions, which they might not be able to obtain elsewhere so conveniently. some account of the epyornis seems to be very properly connected with ornithichnites. the first of these papers was written in october, ; the others in the earlier part of the present year. [illustration: epyornis] the epyornis; or, great bird of madagascar, and its eggs. in the course of the year , an account was circulated of the discovery of an immense egg, or eggs, in the island of madagascar. the size of the eggs spoken of was so disproportionate to that of any previously known, that most persons received the account with incredulity; and, i must confess, i was one of this number. being in paris soon after hearing of this report, i made inquiry on the subject, and was surprised to learn, that the great egg was actually existing in the museum of natural history in paris. in a few days i had an opportunity of seeing a cast of it in the hands of the artist, m. strahl, of whom i solicited one. he informed me that it could not be obtained at that moment; but that, if my request were made known to the administration of the museum, he had no doubt they would accede to it. i accordingly did apply, and also presented them with the cast of a perfect head of mastodon giganteus; and they very liberally granted my request. the distinguished naturalist, professor geoffroy st. hilaire, the second of that honorable name, has made a statement to the academy of sciences, which, though only initiatory, contains many facts of a very interesting nature, some of which i have had an opportunity of verifying; and to him we are indebted for a greater part of the others. the eggs sent to me are, in number, two; one of which was purchased by m. abadie, captain of a french vessel, from the natives. another was soon afterwards found, equal in size. a third egg was discovered in an alluvial stratum near a stream of water, together with other valuable relics of the animal which had probably produced them; but, unfortunately, it was broken during transportation. of the two eggs, one is of an ovoid form, having much the shape of a hen's egg; and the other is an ellipsoid. the ovoid egg is of enormous size, even when compared with the largest egg we are acquainted with. its long diameter exceeds thirteen inches of our english measure, its short diameter eight, and its long circumference thirty-three inches. its capacity is thought to be equal to eighteen liquid pints, or to be six times greater than that of the largest egg known to us (the ostrich), although but twice its length. it is said to be equal to a hundred and forty-eight hen eggs. the ellipsoid egg has its longest diameter somewhat less than that of the ovoid; its short diameter nearly equals that of the other egg, being more than eight inches. the third egg, although broken, has been very useful to science, by displaying the thickness of the shell, which is about one-tenth of an inch. the bones, of which i have received the casts, are three in number, and of great interest. one of them is a characteristic fragment of the upper part of a fibula; the other two, still more interesting, as enabling us to determine the class and genus of the animal to which they belong, exhibit the extremities of the right and left tarso-metatarsal bones. the former is somewhat broken; the latter is nearly perfect, and exhibits the triple division of the inferior extremity of the bone into the three trochleæ or pulley-shaped processes of the struthious birds. it might be mistaken for a bone of the great dinornis, but is distinguished from this by the flatness of the portion above the trochleæ. still less is it one of the bones of the ostrich, its three pulleys being separated from each other by distinct intervals; whereas the pulleys of the ostrich have only one such separation, constituting two distinct eminences. m. geoffroy st. hilaire considered himself justified, from these and other facts, in deciding this bone to belong to a bird of a new genus, to which he gives the name of epyornis, from _aipys_, _high_, _tall_, and _ornis_, _bird_; and, as probably it is a specimen of the largest animal of the family, he affixes the specific name of _maximus_. the size of this bird, inferred from that of its egg, would be vastly superior to that of the ostrich. but if we notice the comparative size of the trochleated extremity of the tarso-metatarsal bone, we shall see that its height would be greatly exaggerated by adopting such a basis for its establishment; in fact, it would not probably exceed a height double that of the ostrich. and, though it must have been superior to that of the dinornis maximus of prof. owen, it might perhaps excel it only by the difference of two or three feet. a bird of twelve or thirteen feet in height would, however, if we stood in its presence, appear enormous, and must have greatly astonished and terrified the natives of madagascar. whether it now exists is uncertain, as it may possibly have a habitation in the wild recesses of the island, which have never yet been visited by any european traveller. the credit of most of the observations and discoveries relating to this remarkable bird is attributable to french naturalists;[a] and it seems to be a duty devolving on english and american navigators to complete the history thus happily begun, and to tell us whether the epyornis still exists in the mountain-forests of madagascar, or at least present us with its extraordinary relics. [footnote a: the following are the names of french travellers, who have been supposed to have seen the eggs of the epyornis in the island of madagascar: m. sganzin, in ; m. goudot, in ; m. dumarele, in ; and m. abadie, in .] fossil impressions.--i. ichnology, a newly created branch of science, takes its name from the greek word _ichnos_, a _track_ or _footstep_, and the tracks themselves have been denominated ichnites, or, when they refer to birds only, ornithichnites, from _ornis_, a _bird_. and this last term has by custom been generally applied to ancient impressions, though not correctly. geology has revealed to us not only the remains of animals and vegetables, but the impressions made by them during their lives, and even the impressions of unorganized bodies. the first notice of these appearances was, as often happens, regarded with indifference or scepticism; but their number and variety enlightened the public mind, and opened a new source of information and improvement. the first remarkable observation made on fossil footsteps was that of the rev. dr. duncan, of scotland, in . he noticed, in a _new red sandstone_ quarry in dumfriesshire, impressions of the feet of small animals of the tortoise kind, having four feet, and five toes on each foot. they were seen in various layers through a thickness of forty feet or more. sandstone, in which these impressions are principally discovered, is a rock composed chiefly of siliceous and micaceous particles cemented together by calcareous or argillaceous paste, containing salt, and colored with various shades of the oxide of iron, particularly the red, gray, brown. it has been remarked by prof. h. d. rogers, that the perfection of the surface containing fossil footmarks is often attributable to a micaceous deposit. the layers of sandstone have been formed by deposits from sea-water, dried in succession; such layers are also seen in the roofing slate. these deposits on the shores of the ocean, having in a soft condition received the impressions of the feet of birds, other animals, vegetables, and also of rain-drops, under favorable circumstances dried, hardened, and formed a rock of greater or less solidity. our colleague, dr. gould, has exhibited to us a specimen of dried clay from the shores of the bay of fundy, containing beautiful impressions, recently made, of the footsteps of birds. the particles brought by the waves, and deposited in the manner described, were derived from the destruction of other rocks previously existing, particularly granite and flint, or silex, the shining atoms of which compose no small part of the sandstone rock. it is easy to conceive, that, while these deposits were taking place in the soft condition, portions of vegetable matters might become intermixed; and that these, with the impressions of the feet and other parts of animals and unorganized substances, might be preserved by the process of desiccation. the agency of internal heat may have also been employed in some cases in baking and hardening these crusty layers. the sandstone rock, though in some places actually in a state of formation at the present time, lies in such a manner in the earth's crust as to indicate an immense antiquity. the age of these beds varies in different situations. the sandstone rocks which contain the greater part of the impressions are called _new red sandstone_, to distinguish them from the _old red_, which is of a greater age. the deposits on connecticut river may not be attributed to the action of this river, but are of higher antiquity, probably, than the river itself, and proceeded from the waves of an ancient sea, existing in a state of the surface of the globe very different from that of the present day. in , tracks were discovered near hildberghausen in saxony, to which prof. kaup, of darmstadt, gave the name of chirotherium, from the resemblance to the impressions of the human hand. on a subsequent examination, prof. owen preferred the name of labyrinthodon, from the resemblance of the folds in the teeth to the convolutions of the brain. various other instances of impressions were seen; and, in the year , dr. deane and mr. marsh, residents of greenfield, noticed impressions resembling the feet of birds in sandstone rocks of that neighborhood. these observations having come to the knowledge of president hitchcock, of amherst college, that gentleman began a thorough investigation of the subject, followed it up with unremitted ardor, and has, since (the date of his first publication), laid before the public a great amount of ichnological information, and really created a new science. dr. deane, on his part, has not been idle: besides making valuable discoveries, he has written a number of excellent papers to record some portion of his numerous observations. in , at the request of my friend dr. boott, i carried to london, for the museum of the royal college of surgeons, various scientific objects peculiar to this country; among which were a number of casts of ornithichnites. these casts were kindly furnished me by president hitchcock, and the government of the royal college thereon voted to present to president hitchcock and amherst college casts of the skeleton of the famous megatherium of south america. these casts were packed, and sent to be embarked in a ship destined for boston, but were unluckily delivered to a wrong shipping house in london, and i lost sight of them for some time. they were at length discovered. after remaining in this situation for more than a year, they were sold at public auction; and, notwithstanding many efforts on my part, i was unable to obtain and transmit them to amherst college. the fossil impressions which have been distinguished in various places in the new red sandstone are those of birds, frogs, turtles, lizards, fishes, mollusca, crustacea, worms, and zoophytes. besides these, the impressions made by rain-drops, ripple-marks in the sand, coprolites or indurated remains of fæces of animals, and even impressions of vegetables, have been preserved and transmitted from a remote antiquity. no authentic human impressions have yet been established; and none of the mammalia, except the marsupials.(?) we must, however, remember that, although the early paleontology contains no record of birds, the ancient existence of these animals is now fully ascertained. remains of birds were discovered in the paris gypsum by cuvier previous to . since that time, they have been found in the lower eocene in england, and the swiss alps; and there is reason to believe that osseous relics may be met with in the same deposits which contain the foot-marks. most of the bird-tracks which have been observed, belong to the wading birds, or grallæ. the number of toes in existing birds varies from two to five. in the fossil bird-tracks, the most frequent number is three, called tridactylous; but there are instances also of four or tetradactylous, and two or didactylous. the number of articulations corresponds in ornithichnites with living birds: when there are four toes, the inner or hind toe has two articulations, the second toe three, the third toe four, the outer toe five. the impressions of the articulations are sometimes very distinct, and even that of the skin covering them. president hitchcock has distinguished more than thirty species of birds, four of lizards, three of tortoises, and six of batrachians. the great difference in the characters of many fossil animals from those of existing genera and species, in the opinion of prof. agassiz, makes it probable that in various instances the traces of supposed birds may be in fact traces of other animals, as, for example, those of the lizard or frog. and he supports this opinion, among other reasons, by the disappearance of the heel in a great number of ornithichnites. d'orbigny, to whom we are indebted for the most ample and systematic work on paleontology ("cours elémentaire de paléontologie et de géologie," vols. - ), does not accept the arrangement of president hitchcock. he objects to the term ornithichnites, and proposes what he considers a more comprehensive arrangement into organic, physiological, and physical impressions. _organic impressions_ are those which have been produced by the remains of organized substances, such as vegetable impressions from calamites, &c. _physiological impressions_ are those produced by the feet and other parts of animals. _physical impressions_ are those from rain-drops and ripple-marks; and to these may be added coprolites in substance. this plan of d'orbigny seems to exclude the curious and interesting distinctions of groups, genera, and species; in this way diminishing the importance of the science of ichnology. fossil impressions have been found on this continent in the carboniferous strata of nova scotia, and of the alleghenies; in the sandstone of new jersey, and in that of the connecticut valley in a great number of places, from the town of gill in massachusetts to middletown in connecticut, a distance of about eighty miles. a slab from turner's falls, obtained for me by dr. deane in , measuring two feet by two and a half, and two inches in thickness, contains at least ten different sets of impressions, varying from five inches in length to two and a half, with a proportionate length of stride from thirteen inches to six. all these are tridactylous, and represent at least four different species. in most of them the distinction of articulation is quite clear. the articulations of each toe can readily be counted, and they are found to agree with the general statement made above as to number. the impressions are singularly varied as to depth; some of them, perfectly distinct, are superficial, like those made by the fingers laid lightly on a mass of dough, while others are of sufficient depth nearly to bury the toes; some of the tracks cross each other, and, being of different sizes, belong to animals of different ages or different species. there is one curious instance of the tracks of a large and heavy bird, in which, from the softness of the mud, the bird slipped in a lateral direction, and then gained a firm footing; the mark of the first step, though deep, is ill-defined and uncertain; the space intervening between the tracks is superficially furrowed; in the settled step, which is the deepest, the toes are very strongly indicated. on the same surface are impressions of nails, which may have belonged to birds or chelonians. the inferior surface of the same slab exhibits appearances more superficial, less numerous, but generally regular. there are three sets of tracks entirely distinct from each other; two of them containing three tracks, and one containing two,--the latter being much the largest in size. in addition, there is one set of tracks, which are probably those of a tortoise. these marks present two other points quite observable and interesting. one is that they are displayed in relief, while those on the upper surface are in depression. the relief in this lower surface would be the cast of a cavity in the layer below; so the depressions in the upper surface would be moulds of casts above. the second point is the non-correspondence of the upper and lower surfaces; i.e. the depressions in the upper surface have not a general correspondence with the elevations on its inferior surface. the tracks above were made by different individuals and different species from those below. this leads to another interesting consideration, that in the thickness of this slab there must be a number of different layers, and in each of them there may be a different series of tracks. to these last remarks there is one exception: the deep impression in which the bird slipped in a lateral direction corresponds with an elevation on the lower surface, in which the impression of these toes is very distinctly displayed, and even the articulations. moreover, one of the tracks on the inferior surface interferes with the outer track in the superior, and tends in an opposite direction, so that this last-described footstep must have been made before the other. it is also observable, that, while all the other tracks are superficial, this last penetrates the whole thickness of the slab; thus showing that the different deposits continued some time in a soft state. on the surfaces of this slab, particularly on the upper, there are various marks besides those of the feet, some of which seem to have been made by straws, or portions of grass, or sticks; and there is a curved line some inches in length, which seems to have arisen from shrinkage. in the collection of mr. marsh,[b] there were two slabs of great size, each measuring ten by six feet, having a great number of impressions of feet, and about the same thickness as the slab under examination. one of these presented depressions; and the other, corresponding reliefs. these very interesting relations were necessarily parted in the sale of mr. marsh's collection; one of them being obtained for the boston society of natural history, and the other for the collection of amherst college. [footnote b: mr. marsh was a mechanic of the town of greenfield, and procured his subsistence by his daily labor. being employed by dr. deane in obtaining the sandstone slabs of ornithichnites, he acquired a taste for the pursuit, entered into it with extraordinary ardor, and accumulated by his own labors a great collection of fine specimens. he unfortunately fell into a consumption, and died in . the collection was sold at public auction for a sum between two and three thousand dollars. the specimens were purchased by the boston society of natural history, by amherst college, and by varioud colleges and scientific associations in this country.] the _physical impressions_, according to professor d'orbigny, are of three kinds, viz.: st, rain-drops; d, ripple-marks; and d, coprolites. i have a slab which exhibits two leptodactylous tracks very distinct, about an inch and a half long, surrounded by impressions of rain-drops and ripple-marks. another specimen exhibits the impressions of rain in a more distinct and remarkable manner. the imprints are of various sizes, from those which might be made by a common pea to others four times its diameter; some are deep, others superficial and almost imperceptible. they are generally circular, but some are ovoid. some have the edge equally raised around, as if struck by a perpendicular drop; and others have the edge on one part faintly developed, while another part is very sharp and well defined, as if the drop had struck obliquely. it has been suggested, that these fossil rain-drops may have been made by particles of hail; but i think the variety of size and depth of depression would have been more considerable if thus made. although we have necessarily treated the subject of fossil footmarks in a very brief way, sufficient has been said to show that this new branch of paleontology may lead to interesting results. the fact that they are, in some manner, peculiar to this region, seems to call upon our society to obtain a sufficient number of specimens to exhibit to scientific men a fair representation of the condition of ichnology in this quarter of our country; and we have therefore great reason to congratulate ourselves, that, through the vigilance and spirit of our members, the society has the expectation of obtaining a rich collection of ichnological specimens. fossil impressions.--ii. since writing the preceding article, i have been able to obtain, through the kindness of president hitchcock, a number of additional specimens of fossil impressions. by the aid of these, i may hope to give an idea of the system of impressions, so far as it has been discovered, without, however, attempting to enter into minute details. for these, i would refer to the account of the "geology of massachusetts," by president hitchcock; to his valuable article published in the "memoirs of the american academy;" and to his geological works generally. the numerous tracks which have been assembled together in the neighborhood of connecticut river have afforded an opportunity of prosecuting these studies to an extent unusual in the primitive rocky soil of new england. these appearances are not, indeed, wholly new. such traces had been previously met with in other countries; but, in their number and variety, the valley of the connecticut abounds above all places hitherto investigated. twenty years have elapsed since the study of ichnology has been prosecuted in this country; and, in this period of time, about forty-nine species of animal tracks have been distinguished in the locality mentioned, according to president hitchcock; which have been regularly arranged by him in groups, genera, and species. i propose now to lay the specimens, recently obtained, before the society, as a slight preparation for the more numerous and more valuable articles which they are soon to receive. the traces found on ancient rocks, as has been shown in the previous article, are those of animals, vegetables, and unorganized substances. the traces of animals are produced by quadrupeds, birds, lizards, turtles, frogs, mollusca, worms, crustacea, and zoophytes. these impressions are of various forms: some of them simple excavations; some lines, either straight or curved, and others complicated into various figures. president hitchcock has based his distinctions of fossil animal impressions on the following characters, viz.:-- . toes thick, pachydactylous; or thin, leptodactylous. . feet winged. . number of toes from two to five, inclusive. . absolute and relative length of the toes. . divarication of the lateral toes. . angle made by the inner and middle, outer and middle toes. . projection of the middle beyond the lateral toes. . distance between tips of lateral toes. . distance between tips of middle and inner and outer toes. . position and direction of hind toe. . character of claw. . width of toes. . number and length of phalangeal expansions. . character of the heel. . irregularities of under side of foot. . versed sine of curvature of toes. . angle of axis of foot with line of direction. . distance of posterior part of the foot from line of direction. . length of step. . size of foot. . character of the integuments of the foot. . coprolites. . means of distinguishing bipedal from quadrupedal tracks. by these characters, president hitchcock has distinguished physiological tracks, or those made by animated beings, into ten groups provisionally. to these may be added, "organic impressions," made by organized bodies; and the impressions made by inanimate bodies, called "physical impressions." the specimens under our hands enable us to give some notion of the distinctions which characterize the greater part of these groups. * * * * * group first--struthiones. the ostrich-tracks present a numerous natural and most remarkable group; remarkable from the great size of some species,--all of them tridactylous and pachydactylous. the ostrich of the old world has only two toes, but this family exists in south america at the present time under the name of rhea americana; and tracks of an animal, probably of the same family, are found in the numerous impressions near connecticut river,--all of them having three toes in front, and the rudiment of a fourth behind. this group contains a number of genera. the first genus, denominated _brontozoum_, presents the tracks of a most extraordinary bird. these tracks appear less questionable since the discovery in madagascar of the eggs of the epyornis. the tracks of the largest species, the brontozoum giganteum, are four times the magnitude of those made by the existing ostrich of africa. they are very numerous, and congregated together. the foot of the brontozoum giganteum, including the inferior extremity of the tarso-metatarsal bone, which makes a part of the foot, measures in our specimen twenty inches; in the mastodon giganteus, the foot measures twenty-seven inches; the width also is less, being ten inches across the metacarpals, while that of the mastodon is twenty-two: but the one is a bird, the other a quadruped. the toes are three in number, and present the same divisions with existing birds; the inner toe having three, the middle four, the outer five phalanges. some of the articulations of the toes of this noble specimen are remarkable for the manner in which they illustrate the mode of formation of the tracks. these phalanges have become separated from the solid rock in which they were encased, so as to be removable at pleasure; and they thus show that the whole foot is not a simple impression in the rock which contains it, but a depression filled by foreign materials, i.e. by sand, clay, and other relics of pre-existing rocks. these materials had been gradually deposited in the mould formed by the bird's foot, and are therefore independent of this rock, in the same way as the plaster-of-paris cast of a tooth, or any other body, is independent of the mould to which it owes its form. the impressions are in gray sandstone. on the reversed surface of the slab is seen a small piece of broken quartz, about half an inch square. this piece forms a beautiful illustration of a part of the process by which the sandstone rocks are formed. the second species of the same genus is the brontozoum sillimanium. of this we have three specimens; the tracks have the same general character with the preceding, but are smaller. the third species of this genus is styled the brontozoum loxonyx, from _loxos_, a _bow_, and _onyx_, a _nail_,--a curved nail. it is smaller than the sillimanium, and has the nail set to one side. the fourth species, still smaller, is the brontozoum gracillimum. on this slab the impressions are in relief; viz.: st, of brontozoum gracillimum; d, of brontozoum parallelum; d, of the track of a tortoise, fourteen inches long, and two wide. other extensive eminences and depressions, with rain-drops, may be observed on the same surface. the fifth species is called brontozoum parallelum, from the tracks being on a line with each other. of this there are two specimens, one of them, however, being a single track. on the surface of the other slab there are at least five distinct tracks, one of them being a small new and undescribed species,--thus making the whole number of species of brontozoum which we possess to be at least six. the second genus of struthiones is called _Æthyopus_, from _aithuia_, a _gull_, and _pous_, a _foot_,--gull-footed. this genus is smaller than the brontozoum giganteum; and we have two species, viz. the Æthyopus lyellianus, which is the larger, and two specimens of Æthyopus minor. all of these are distinguished from the preceding genus by the winged foot, and in the lyellianus by the shallowness of the impression. the Æthyopus minor is not always distinguished by the superficiality of its impression. this is sometimes deep. therefore this character may not be considered a distinctive one, or the Æthyopus minor might be referred to another genus. of the two specimens of this latter species, the first is in depression, tridactylous. the depressions are deep with rain-drops, marks of quadrupeds and zoophytes over the whole surface. the ornithichnic impressions are two in number; one superficial, the other very deep. the reversed surface of this slab contains one tridactylous impression in relief. the second specimen has three depressions; two of which are superficial, and the third is quite deep, displaying, by a depressed surface, the webbed character of the foot. * * * * * group second. we shall take, to characterize this group, the _argozoum_, from _argês_, _swift_, _winged_. of this genus there are two species, the larger of which is the argozoum disparidigitatum. it is leptodactylous, and remarkable for the length of the middle toe. we have another species, which is smaller than the last named, and in which the toes are nearly of equal length; hence called argozoum paridigitatum. the other genus of this group is the platypterna, and our specimen is named _deaniana_. this genus is remarkable for the width of the heel; hence the name, from _platys_, _broad_, and _pterna_, _a heel_. it has three toes like the other genera of this group. * * * * * group third. this and the succeeding group are tetradactylous; having one toe behind, three forwards. the third group is leptodactylous; foot usually small, but sometimes of medium size. of it we have two specimens, viz.: ornithopus gallinaceus, and ornithopus gracilis. the former is so called from the resemblance to the domestic fowl: for convenience sake, in this and other instances, we use the whole for a part. it is about three inches in length, and the ornithopus gracilis about two. this latter specimen is particularly interesting. it consists of two parts, which open like the covers of a book. these covers present four impressions: first, the superficial, which is distinct, slender, and beautiful--the heel is broad; second, corresponding with this depression and on the inside, is a figure in relief as distinct as the depression; third, on the inside of the second cover is a depression corresponding with the relief last mentioned; fourth, on the outer side is a second relief corresponding with the second depression, but less distinct than either of the other three, still, however, exhibiting three toes pointing anteriorly, but the hind toe is wanting. the whole of this double slab forms a series of cameos and intaglios, measuring four inches by three, and in thickness an inch and a quarter. * * * * * group fourth. of the fourth group we have five specimens. the _triænopus_, so called from its resemblance to a trident, has besides three leptodactylous toes pointing forwards, a fourth extending backwards in a remarkable way, like the handle of a trident; the impression, however, being expanded so as to show an extensive displacement of the mud. all the specimens of triænopus are in a beautiful red shale, very thin and fragile, but presenting well-defined impressions, generally about three inches long. there are two species to this genus. of the triÆnopus emmonsianus we notice three impressions in relief. in another specimen there is the appearance of a part of the toes of the anomoepus scambus, and on the upper side are seen two excavations corresponding with the three impressions. in the last slab, the track of the triÆnopus baileyanus appears to have been made by two feet placed successively in the same spot, which led president hitchcock to suspect it might have been made by a quadruped. one of the specimens has the triænopus tracks intermixed in a peculiar way with other impressions. the specimen representing the genus harpedactylus is larger than the preceding; and, though leptodactylous, the toes are much broader and also more curved, whence the name harpedactylus, _sickle-finger_, from _harpê_ and _daktylos_. * * * * * group fifth. the fifth group differs much from the four previous ones. in this and the following groups we pass from the vestiges of birds to those of other animals, some of which are bipeds, some quadrupeds. many impressions are without any distinct character, belonging probably to the lower animals, to vegetables, and unorganized bodies. the fifth group comprehends the tracks of an extraordinary animal, the otozoum.[c] the name which has been given to it is taken from that of an ancient giant, otus, who with his brother ephialtes, according to heathen mythology, made war with the gods. these fabled giants were, at nine years of age, nine cubits in width and nine fathoms in height. [footnote c: the specific name of moodii has been attached to the otozoum, from its having been discovered by mr. moody.] the foot is divided into four toes; the two outer of which seem to be connected by a common basis. the inner toe has three phalanges; the second toe, also three; the third and fourth toes, four each. the first is the shortest, the second longer, the third longest, the fourth shorter than the third. it will appear, then, that this track differs from that of birds in the number of toes pointing forwards; these being four, while in birds the forward toes are only three. there is a difference also in the number and arrangement of the articulations. the track in our possession is twenty inches long by thirteen and a half inches broad. the rock in which it is imbedded is a dark-colored sandstone. president hitchcock has a slab showing a regular series of tracks of this animal; the distance between the steps being about three feet, and the tracks equidistant and alternate, which would not be the case if the animal had been quadrupedal. in a quadruped, the horse for example, the hind feet are set down near the fore feet, and sometimes even strike them. hence it must be inferred that the track in question was that of a biped, or of a quadruped which did not use its fore feet in progression, like a kangaroo. we naturally ask, what kind of biped could this have been? evidently not a man, the size of the foot being too large to admit such a supposition; nor could it have been a bird, the number of toes and their direction not admitting this hypothesis. tetradactylous birds, or those which have four toes, have only three of them directed forwards, and the fourth backwards, generally. there are, however, exceptions; some birds have four toes directed forwards: this is the fact with the hirundo cypselus and the pelicanus aquilus of linnæus, or man-of-war bird. but the articulations are different in the two animals, birds having regularly two, three, four, and five phalanges, and the spur, where it exists, supported by a single osseous phalanx; whereas the otozoum has three phalanges in the inner and second toe, four in the third and fourth toes. in this last arrangement, the otozoum is decidedly different from all known birds. it is not likely to have been a tortoise or a lizard. the kangaroo has four feet, and uses only two in progression, moving forward by leaps; also, like the otozoum, it has four toes; but the size of the toes does not accord with that of the otozoum, nor is the structure of the foot the same, so far as we know. it has been suggested by professor agassiz, that this animal might have been a two-footed frog. nature had, in those days, animal forms different from those we are acquainted with; and this might have been the fact with the otozoum. * * * * * group sixth. we have in this group a specimen of the track of a four-footed animal, which may have been a frog, though different from ours. the feet are unequal in size, and present a different number of toes. in existing frogs there are four toes in the fore feet, and five in the hind; but, in the specimen before us, the front toes are five in number, and the back toes three. it is called, therefore, anomoepus, _unequal-footed_. these impressions are in the red shale of hadley, and very distinct. in some of them the lower leg is indicated, forming an impression six or seven inches long. the feet being smaller than the legs, the impression made by the latter is more expanded, superficial, and broader, yet still very definite. the opinion of president hitchcock and dr. deane is, that the different impressions of five and three toes are those of the anterior and posterior extremities of one animal, which, from the size of the limbs, might be a frog three feet high. on the same schist with these footmarks, are other curious impressions. the back of the slab is almost covered with the imprints of rain-drops. in the midst of these is a tridactylous impression, probably of a quadruped, crossed at its root by a single depression, nearly an inch broad, and two and a half long: this seems to form part of another broad superficial impression of about seven by four inches, which is probably also quadrupedal. other parts present the impressions of nails and worm-tracks. at the opposite end is a deep, smooth, regular excavation, which might have been made by a medusa. * * * * * group seventh. the seventh group contains the impressions of the feet of saurians or lizards. we have a specimen of quadrupedal marks, with five toes to each foot, about an inch long, which may have been made by these animals. the impressions are small, but very distinct. there are lizards of the present day with five toes, about the size of these impressions; and these may, therefore, be set down as belonging to this order of reptiles. like a number of the last-named specimens, they are in red shale. * * * * * group eighth. the eighth group is assigned by president hitchcock to the chelonian or turtle tribe. the slab bearing impressions of brontozoum gracillimum has a mark about fourteen inches long and two wide, which may be attributed to the plastron or breast-plate of the tortoise. on the slab from turner's falls there is a longitudinal furrow, which might have been made by the tail of a turtle; and in various of our slabs are impressions which we think belong to this tribe. we shall have occasion to notice hereafter remarkable tracks of these animals in the old red of morayshire, in scotland. the most distinct of the traces of chelonians are on the large slab lately obtained for me by president hitchcock from greenfield. (_vide_ plate.) this interesting slab contains the traces of quadrupeds, various birds, and two trails of chelonians: the largest of these is nearly five feet long, and four inches in diameter. the trail is composed of a number of parallel elevations, comparatively superficial. * * * * * group ninth. of the ninth group, containing the marks of annelidæ, crustacea, and zoophytes, we have various specimens. the impressions of insects do not seem as yet to have been distinguished on the ancient rocks. there is reason to believe, however, that many of the marks we discover in the rocky beds might have been made by the feet and bodies of large insects; and small species of the same tribes have been found imbedded in, and actually constituting, immense masses of calcareous and siliceous rocks. the tracks of worms are numerous. no doubt these worms drew together a concourse of birds to the shores on which they rolled. on various slabs we find long cylindrical furrows, about the eighth of an inch in diameter, and of different lengths; one of them, in the slab from dr. deane, being eight or nine inches long. to these impressions the name of herpystezoum, from _herpystês_, _crawling_, has been given. they vary, however, and some of them are very likely to be the tracks of the common earth-worm, or of some species of worm which existed when these rocks were formed. these impressions vary in length and in diameter; some of them are moderately regular, and others irregularly curved. very interesting tracks have been found in the ancient potsdam white sandstone of beauharnais, on the st. lawrence, by mr. logan, an excellent geologist of canada, and determined by professor owen to belong to crustacea, crabs. the number of impressions made by each foot is sometimes seven, sometimes eight, and even more. this track, showing the traces of crustacea, goes to form another link in the chain of fossil footsteps. the medusæ, commonly called jelly-fish, dissolving as they do under the influence of the sun and air, would hardly be expected to leave their traces impressed on ancient rocks. professor d'orbigny, however, has watched the dissolution of these animals on the sea-shore, and found that, after wasting, they may leave their impressions on the sand; which, not being disturbed by a high tide for nearly a month, retains the impression of the zoophyte, and serves as a mould to receive materials which take a cast and transmit it to subsequent ages. we find one of these impressions on the slab of the anomoepus scambus; and president hitchcock, having examined it, is of opinion that it retains the traces of a medusa. the impression is about five inches in diameter, of a darker color and smoother texture than the rest of the rock. its edges fade away gradually in the surface of the subjacent sandstone. a similar impression is found on the superior surface of the slab containing the argozoum. * * * * * group tenth. the tenth group contains the harpagopus, a name derived from _harpagê_, _seizure_, _rapine_. it is represented by president hitchcock as having the form of a drag. the figure given by him resembles in a degree the foot of the african ostrich; being a long thick toe, with a shorter one, not unlike a thumb, on the side. an impression approximating this, but of small size, may be seen on the slab of the anomoepus scambus. * * * * * the formation of bird-tracks is well represented by a clay specimen, about an inch thick, and ten inches long. this is a piece of dried clay, obtained by president hitchcock from the banks of the connecticut, and produced by washings from clay on the shore above, covered with foot-impressions of a small tridactylous bird, and dried in the sun. this piece shows, in a way not to be questioned, the manner in which the ancient vestiges were produced. sir charles lyell noticed a similar fact on the banks of the bay of fundy. organic impressions. the _second_ great division of fossil impressions is called organic, meaning impressions made by organized bodies; the bones of animals, fishes, and vegetables. near one extremity of the slab of the ornithopus gallinaceus is an elevation, about a foot long, and between one and two inches wide, projecting from the surface nearly half an inch. it has the appearance of a round bar of iron imbedded in the rock, which is clayey sandstone. this apparent bar of iron was probably a bone, buried in the stone, now silicified and impregnated with iron; the animal matter having entirely disappeared. in the slab of the brontozoum sillimanium is a projection about seven or eight inches long, and half an inch wide; probably the bone of an animal, perhaps a clavicle of the brontozoum giganteum. the vestiges of fishes are very numerous in the sandstone rocks of connecticut river. we have not less than two dozen specimens from this locality; a number equal to all the other specimens in our collection. these impressions of fishes are generally from three to six inches long, and three or four inches wide. they are of the grand division denominated by professor agassiz "heterocercal," having their tails unequally bilobed, from the partial prolongation of the dorsal spine; and they are considered to be of lower antiquity than the fishes which are entirely heterocercal. the most remarkable of the fish-specimens in our collection is a cephalaspis (?): this fish is found in the specimen containing tracks of the brontozoum gracillimum, and traces of a turtle or tortoise. this fossil was discovered in the upper layer of the old red sandstone of scotland, and had been mistaken by some for a trilobite: to us it appeared to be a limulus, but further observation leads us to believe it to be a _cephalaspis_. it exhibits a convex disc, four inches across, by two inches from above downwards, and a tail at right angles with the disc, the uncovered part of which is three inches long. the animal has been described by professor agassiz as being composed of a strong buckler, with a pointed horn at either termination of the crescent, and an angular tail. to the vegetable impressions discovered among the sandstone rocks a peculiar name has not yet been assigned. when, however, we consider the strong probability that many impressions of stalks, leaves, fruits, and other parts of vegetables, may be hereafter discovered in these rocks, it will be found convenient to have a distinctive denomination. vast numbers of vegetable impressions of a distinct and beautiful appearance, and in great variety, have been found in the coal-formation, which is nearly allied to the sandstone: such are the sigillaria, stigmaria, equisetaceæ, lycopodiaceæ, coniferæ, cycadeæ, &c. it is sufficient to say that the number of these has been already swelled to many hundreds: we must also believe, that some of the impressions in sandstone rocks which have been assigned to other substances ought to be attributed to vegetables. we may, therefore, venture to call the vegetable impressions "phytological." a number of our slabs bear impressions of vegetables; either twigs of trees, or spires of plants. in a fragment broken from one of the toes of the brontozoum giganteum, we see a cylindrical depression, three inches long, and half an inch in diameter, marked by transverse lines, about the sixth of an inch apart, and presenting an unquestionable appearance of a fragment of a twig of an ancient vegetable, which had been trodden under the foot of the mighty brontozoum. on the reversed surface of the same slab are found impressions, which were produced by a number of fragments of sticks, five or six inches long, lying at right angles, or nearly so. one of these sticks has been broken, and its pieces are slightly displaced from each other. various other specimens contain the marks of sticks, or twigs of trees. the striæ, so distinctly discernable in a number of these portions, having been compared with twigs of the existing coniferæ (?), were found to resemble them. some of these sticks show the appearance of incipient carbonization; yet the rock is sandstone, presenting, as already mentioned, distinct appearances of quartz, and other substances of which the arenaceous rocks are composed. physical impressions. the _third_ great division of impressions in the sandstone rocks is called physical, meaning those made by inanimate and unorganized substances; such are rain-drops, ripple-marks, and coprolites. . marks of rain-drops, described on page , appear to be quite common. we have two or three specimens in relief, and as many in depression. they occur as follows: st, on the upper surface of the slab first described; d, on that of the platypterna; d, on that of the Æthyopus lyellianus; th, on that of the brontozoum gracillimum; th, on that of the Æthyopus minor; th, on that of the anomoepus scambus; th, on the recent clay; also in one small hand-specimen, and in a second containing two fishes. they show that, in those ancient periods when the brontozoum giganteum and the otozoum resided in these parts, showers were frequent, and probably abundant for the supply of the wants and the gratification of the appetites of these animals, then common, but which now appear to us so extraordinary. . ripple-marks are seen in a number of these pieces; for example, on the slab first described, on the brontozoum sillimanium slab, on the brontozoum gracillimum slab, on one of the triænopus, and on the upper surface of the greenfield slab. these marks are represented by parallel curves, or straight lines, distant from each other from half an inch to an inch, and presenting a slight degree of prominence. there is another form of ripple-marks(?), differing from those above described. these are of a circular and mammillary form: they are strewed thickly, like little islets, approximating to each other. they are seen distinctly on one of the slabs of the brontozoum sillimanium, on that of the Æthyopus lyellianus, and some others. whether they are to be considered as accumulations of sand and clay, formed by the action of the sea, we are uncertain; but there seems to be no other cause to which they can be assigned with so great probability. . _coprolites_, the fossilized ejections of animals, are intermixed with other animal vestiges in the sandstone of connecticut river, and afford additional proof of the former existence of animals about these rocks. * * * * * the latest accounts of fossil footprints we have had occasion to notice are those of the crustacea, already mentioned, as found in canada, and of the chelonian in scotland. the canadian impressions, called by professor owen protichnites, were discovered in the year , and were laid before the london geological society in . the most remarkable circumstance about them was their existence, as already stated, in a white sandstone, near the banks of the river st. lawrence, at beauharnais. this sandstone, which has been described by new york geologists under the name of potsdam, is thought to belong to the silurian system, and to have a higher antiquity than even the "old red." the scotch footsteps are situated in the old red sandstone, and are those of a chelonian. so that we have now two series of tracks, the crustacea in canada and the chelonian in scotland, of higher antiquity than any which had been previously discovered. * * * * * on a review of the labors of president hitchcock, we are struck with admiration at the immense details that, in the midst of arduous official and literary duties, he has been able to go through with in the period since the foot-tracks were discovered on connecticut river. although his labors should be modified by succeeding observers, science must be ever grateful to him for laying the foundation, and doing so much for the completion, of a work so great, novel, and interesting. this inquiry seems to us to promise a rich variety; and we hope that president hitchcock and other observers will continue to explore and cultivate it with undiminished zeal. description of the plate. we are indebted to photography for enabling us to represent the remarkable slab from greenfield, and its numerous objects, in a small space, yet with perfect accuracy. this slab is four feet seven and one-half inches in one direction, and four feet one inch transversely to this; in thickness it measures about an inch. it is composed of gray sandstone, in which the micaceous element is conspicuous, and contains many interesting impressions on both surfaces. the most interesting surface is the inferior; and the objects are, of course, presented in relief. they are, first, two chelonian tracks; second, four sets of bird-tracks; third, footsteps of an unknown animal. the _chelonian tracks_ are two in number: the longest measures four feet ten inches; the shorter, two feet nine inches. both of these impressions are made apparently by the plastron of the turtle. they are from four to eight inches in width, and composed of elevated striæ. these striæ are formed by raised lines, pursuing a course generally regular, but accompanied with some inflections: they are, as the plate represents, very distinct. the shorter track appeared to me to be crossed by another; but the photographic impression, though only a few inches long, enabled me to ascertain that this appearance was produced by bird-tracks above and below. the _bird-tracks_ are all tridactylous. the first set lies above and to the right of the shorter turtle-track, and is composed of only two steps, proceeding in the course of the plate downwards. the second set of bird-tracks has five impressions, extending from the right superior pointed angle of the slab across the small turtle-track to the larger, in which it is lost. the third set of bird-tracks begins by an impression larger than any other on the piece at the left extremity of the longer turtle-track; and the remainder, three in number, descending towards the right, are the least distinct of any. the fourth set of bird-tracks begins below the longer turtle-track, and ascends by four impressions, crossing the track till it meets the first. the most curious track, consisting of six digitated impressions, still remains. the first is seen on the left of the longer turtle-track, near the largest bird-track; the second is on the track; the third is above the track; the others cross the slab by fainter impressions. each of them is composed by two feet, and each foot contains four toes, which are seen more distinctly in some impressions than in others. the largest of these double tracks is about three inches in diameter. perhaps it would be useless to speculate upon what kind of animal they were made by. there is a similarity between these and the tracks of the anomoepus scambus, spoken of in the sixth group. in the latter, however, the toes are five and three. some experienced persons think they are tracks of the mink, mustela lutreola, an animal common at the present day in these parts. this has five toes; but it may be in this as in some other digitigrades, that one of the toes in each foot does not make an impression; or perhaps it is safer to believe, till further investigation is made, that it was an animal of a construction not now existing. the direction of these tracks presents a puzzle we are not able to unravel; it exhibits the impressions of four toes, and we have supposed it might possess five. in either of these cases, we have no right to consider it a bird-track, but probably a reptile or a mammal. admitting this to be the fact, we are unable to account for the direction of the steps, which is not alternate, as in the quadruped, but in straight lines. in other words, this animal, supposed to have four legs, gives us the impressions of two only, and both of these placed together. when the tridactylous tracks are attentively considered, compared with each other, and with the digitated tracks, they appear to exhibit the character of the impressions of the feet of birds so very decidedly, that it would require something more than a philosophic incredulity to question their ornithic origin. the other side of this slab contains interesting impressions. in the first place, this surface is covered with ripple-marks, each about two inches broad, extending with various degrees of distinctness across the slab, and having an interval of an inch. the width of the ridges is greater than in any of the specimens we have seen. this surface is almost covered by rain-drops. it has also, among other impressions, one which has been drawn by mr. silsbee, our photographist, and represented by the figure below of its proper size. this figure, nearly four and a half inches in length, is an exact resemblance in form, but not in size, of the great otozoum, as depicted by president hitchcock, and shown by the actual impression, in our hands, of the great foot, twenty inches long, and of proportionate breadth. the form of the heel, or posterior part of the foot, is the same in the two figures; the toes are equal in both, viz. four in number; the two internal toes correspond in their articulations, and the two external are nearly alike, with a little allowance for a different amount of adipose texture. whether this was the impression of an infant otozoum, i pretend not to determine: the drawing was taken by a gentleman who knew nothing of the otozoum. there are similar impressions, smaller than that last described, on the same surface. the stone, though now very hard and intractable, having resisted all the chemical agents we could employ, must have remained in a soft state for some time; for the impressions of the foot shown below penetrate to the opposite surface. [illustration: fossil foot impression] in this description we have not attempted to point out all the objects worthy of interest on both sides of this curious slab. every part of it is full of interest, and presents a field for protracted observations. the surface represented in the plate may, by the aid of a magnifier, be studied without the presence of the stone itself; for the photographic art displays the most minute objects without alteration or omission. * * * * * transcriber's notes. with the exception of several presumed typographical error which have been changed as noted below, the text presented is that shown in the original printed version. the original text included greek characters. for this text version these letters have been replaced with transliterations. also, the 'ae' and 'ae' ligatures are included (for examples, Æthyopus and striæ); but the 'oe' ligatures (for example, anomoepus) are shown as 'oe' for readability as the ligature character is not present in many fonts. typographical errors: "alleghanies" => "alleghenies" (pg. ) "mastodon giganteus." => "mastodon giganteus," (pg. ) emphasis notation: _text_ - italicized chambers's elementary science manuals. geology by james geikie, ll.d., f.r.s. of h.m. geological survey; author of 'the great ice age.' [logo] w. & r. chambers london and edinburgh edinburgh: printed by w. and r. chambers. preface. the vital importance of diffusing some knowledge of the leading principles of science among all classes of society, is becoming daily more widely and deeply felt; and to meet and promote this important movement, w. & r. chambers have resolved on issuing the present series of elementary science manuals. the editors believe that they enjoy special facilities for the successful execution of such an undertaking, owing to their long experience--now extending over a period of forty years--in the work of popular education, as well as to their having the co-operation of writers specially qualified to treat the several subjects. in particular, they are happy in having the editorial assistance of andrew findlater, ll.d., to whose labours they were so much indebted in the work of editing and preparing _chamber's encyclopædia_. the manuals of this series are intended to serve two somewhat different purposes: . they are designed, in the first place, for self-instruction, and will present, in a form suitable for private study, the main subjects entering into an enlightened education; so that young persons in earnest about self-culture may be able to master them for themselves. . the other purpose of the manuals is, to serve as text-books in schools. the mode of treatment naturally adopted in what is to be studied without a teacher, so far from being a drawback in a school-manual, will, it is believed, be a positive advantage. instead of a number of abrupt statements being presented, to be taken on trust and learned, as has been the usual method in school-teaching; the subject is made, as far as possible, to unfold itself gradually, as if the pupil were discovering the principles himself, the chief function of the book being, to bring the materials before him, and to guide him by the shortest road to the discovery. this is now acknowledged to be the only profitable method of acquiring knowledge, whether as regards self-instruction or learning at school. for simplification in teaching, the subject has been divided into sub-sections or articles, which are numbered continuously; and a series of questions, in corresponding divisions, has been appended. these questions, while they will enable the private student to test for himself how far he has mastered the several parts of the subject as he proceeds, will serve the teacher of a class as specimens of the more detailed and varied examination to which he should subject his pupils. note by the author. in the present manual of geology it has been the aim of the author rather to indicate the methods of geological inquiry and reasoning, than to present the learner with a tedious summary of results. attention has therefore been directed chiefly to the physical branches of the science--palæontology and historical geology, which are very large subjects of themselves, having been only lightly touched upon. the student who has attained to a fair knowledge of the scope and bearing of physical geology, should have little difficulty in subsequently tackling those manuals in which the results obtained by geological investigation are specially treated of. contents. page introductory classification of rocks mineralogy rock-forming minerals petrology-- mechanically formed rocks chemically formed rocks organically derived rocks metamorphic rocks igneous rocks structure and arrangement of rock-masses-- stratification, &c.; mud-cracks and rain-prints; succession of strata; extent of beds; sequence of beds--joints; cleavage; foliation; concretions; inclination of strata; contemporaneous erosion; unconformability; overlap; faults; mode of occurrence of metamorphic and igneous rocks; mineral veins - dynamical geology-- the atmosphere as a geological agent of change water as a geological agent of change geological action of plants and animals subterranean forces metamorphism physiography palÆontology historical geology questions [illustration: geology] introductory. . _definition._--geology is the science of the origin and development of the structure of the earth. it treats of the nature and mode of formation of the various materials of which the earth's crust is composed; it seeks to discover what mutations of land and water, and what changes of climate, have supervened during the past; it endeavours to trace the history of the multitudinous tribes of plants and animals which have successively tenanted our globe. in a word, geology is the physical geography of past ages. . _rocks._--every one knows that the crust of the earth is composed of very various substances, some of which are hard and crystalline in texture, like granite; others less indurated and non-crystalline, such as sandstone, chalk, shale, &c.; while yet others are more or less soft and incoherent masses, as gravel, sand, clay, peat, &c. now, all these heterogeneous materials, whether they be hard or soft, compact or loose, granular or crystalline, are termed _rocks_. blowing sand-dunes, alluvial silt and sand, and even peat, are, geologically speaking, rocks, just as much as basalt or any indurated building-stone. the variety of rocks is very great, but we do not study these long before we become aware that many kinds which present numerous contrasts in detail, yet possess certain characters in common. and this not only groups these diverse species together, but serves also to distinguish them from other species of rock, which in like manner are characterised by the presence of some prevalent generic feature or features. _classification of rocks._--all the rocks that we know of are thus capable of being arranged under _five_ classes, as follows: i. mechanically formed. ii. chemically formed. iii. organically derived. iv. metamorphic. v. igneous. . the mechanically formed class comprises a considerable variety of rocks, all of which, however, come under only two subdivisions--namely, _sedimentary_, and _eolian_ or _aërial_, the former being by far the more important. of the _sedimentary_ group, there are three rocks which may be taken as typical and representative--namely, _conglomerate_ or _puddingstone_, _sandstone_, and _shale_. a short examination of the nature of these will sufficiently explain why they come to be grouped together under one head. _conglomerate_ consists of a mass of various-sized rounded stones cemented together; each stone has been well rubbed, and rolled, and rounded. it is quite obvious that the now solid rock must at one time have existed in a loose and unconsolidated state, like gravel and shingle. nor can we resist the conclusion that the stones were at one time rolled about by the action of water--that being the only mode in which gravel-stones are shaped. again, when we have an opportunity of examining any considerable vertical thickness of conglomerate, we shall frequently observe that the stones are arranged more or less definitely along certain lines. these, there can be no question, are _lines of deposition_--the rounded stones have evidently not been formed and accumulated all at once, but piled up gradually, layer upon layer. and since there is no force in nature, that we know of, save water in motion, that could so round and smooth stones, and spread them out in successive layers or beds, we may now amplify our definition of conglomerate, and describe it as a _compacted mass of stones which have been more or less rounded, and arranged in more or less distinct layers or beds, by the action of water_. . _sandstone_ may at the outset be described as a _granular non-crystalline rock_. this rock shews every degree of coarseness, from a mass in which the constituent grains are nearly as large as turnip-seed, down to a stone so fine in the grain that we need a lens to discover what the particles are of which it is composed. when these latter are examined, they are found to exhibit marks of attrition, just like the stones of a conglomerate. sharp edges have been worn off, and the grains rounded and rubbed; and whereas lines of deposition are often obscure, and of infrequent occurrence in conglomerate--in sandstone, on the contrary, they are usually well marked and often abundant. we can hardly doubt, therefore, that sandstone has also had an _aqueous_ origin, or in other words, that it has been formed and accumulated by the force of water in motion. in short, sandstone is merely compacted sand. . if it be easy to read the origin of conglomerate and sand in the external character of their ingredients, and the mode in which these have been arranged, we shall find it not less easy to discover the origin of _shale_. shale is, like sandstone, a granular non-crystalline rock. the particles of which it is built up are usually too small to be distinguished without the aid of a lens, but when put under a sufficient magnifying power, they exhibit evident marks of attrition. in structure it differs widely from sandstone. in the latter rock the layers of deposition, though frequently numerous, are yet separated from each other by some considerable distance, it may be by a few inches or by many yards. but in shale the layers are so thin that we may split the rock into _laminæ_ or plates. now we know that many sedimentary materials of recent origin, such as the silt of lakes, rivers, and estuaries, although when newly dug into they appear to be more or less homogeneous, and shew but few lines of deposition, yet when exposed to the action of the atmosphere and dried, they very often split up into layers exhibiting division planes as minute as any observable in shale. there is no reason to doubt, therefore, that shale is merely compacted silt and mud--the sediment deposited by water. it becomes evident, therefore, that conglomerate, sandstone, and shale are terms of one series. they are all equally sedimentary deposits, and thus, if we slightly modify our definition of conglomerate, we shall have a definition which will include the three rocks we have been considering. for they may all be described as _granular non-crystalline rocks, the constituent ingredients of which have been more or less rounded, and arranged in more or less distinct layers, by the action of water_. . the _eolian_ or _aërial_ group of rocks embraces all natural accumulations of organic or inorganic materials, which have been formed upon the land. the group is typically represented by _débris_, such as gathers on hill-slopes and at the base of cliffs, by the _sand-hills_ of deserts and maritime districts, and by _soil_. all these accumulations owe their origin to atmospheric agencies, as will be more particularly described in the sequel. as the _sedimentary_ and _eolian_ rocks are the results of the _mechanical_ action of water and the atmosphere, they are fitly arranged under one great class--the mechanically formed rocks. . chemically formed rocks constitute another well-marked class, of which we may take _rock-salt_ as a typical example. this rock has evidently been deposited in water, but not in the manner of a sedimentary bed. it is not built up of water-worn particles which have been rolled about and accumulated layer upon layer, but has been slowly precipitated during the gradual evaporation of water in which it was previously held in solution. its formation is therefore a chemical process. various other rocks come under the same category, as we shall afterwards point out. . the organically derived class comprises a number of the most important and useful rock-masses. _chalk_ may be selected as a typical example. even a slight examination shews that this rock differs widely from any of those mentioned above. conglomerate, sandstone, shale, &c. are built up of pebbles, particles, grains, &c. of various inorganic materials. but chalk, when looked at under the microscope, betrays an organic origin. it consists, chiefly, of the hard calcareous parts of animal organisms, and is more or less abundantly stocked with the remains of corals, shells, crustaceans, &c. in every degree of preservation; indeed, so abundant are these relics, that they go to form a great proportion of the rock. _coal_ is another familiar example of an organically derived rock, since it consists entirely of vegetable remains. . the metamorphic class, as the name implies, embraces all those rocks which have undergone some decided change since the time of their formation. this change generally consists in a re-arrangement of their constituent elements, and has frequently resulted in giving a crystalline texture to the rocks affected. hence certain sedimentary deposits like sandstone and shale have been changed from granular into crystalline rocks, and the like has happened to beds of limestone and chalk. _mica-schist, gneiss_, and _saccharoid marble_ are typical of this class. . the igneous rocks are those which owe their origin to the action of the internal forces of the earth's crust. most of them have been in a state of fusion, and betray their origin by their crystalline and sometimes glassy texture, and also, as we shall see in another section, by the mode of their occurrence. _lava_, _basalt_, and _obsidian_ are characteristic types of this group of igneous rocks. another group embraces a large variety of igneous rocks which are non-crystalline, and vary in texture from fine-grained, almost compact, bedded masses, like certain varieties of _tuff_, up to coarse, irregular accumulations of angular stones imbedded in a fine-grained or gritty matrix, like _volcanic breccia_ and _volcanic agglomerate_. mineralogy. . having learned that all the rocks met with at the surface of the earth's crust are capable of being arranged under a few classes, we have now to investigate the matter more in detail. it will be observed that the classification adopted above is based chiefly upon the external characters of the constituent ingredients of the rocks, and the mode in which these particles have been collected. in some rocks the component materials are crystalline, in others they are rounded and worn; in one case they have been brought together by precipitation from an aqueous solution, or they have crystallised out from a mass of once molten matter; in another case their collection and intimate association is due to the mechanical action of the atmosphere or of water, or to the agency of the organic forces. we have next to inquire what is the nature of those crystals and particles which are the ingredients of the rocks? the answer to this question properly belongs to the science of mineralogy, with which, however, the geologist must necessarily make some acquaintance. . _granite--its composition._--it will tend to simplify matters if we begin our inquiry by selecting for examination some familiar rock, such as _granite_. this rock, as one sees at a glance, is crystalline, nor is it difficult to perceive that three separate kinds of ingredients go to compose it. one of these we shall observe is a gray, or it may be, clear glassy-looking substance, which is hard, and will not scratch with a knife; another is of a pink, red, gray, or sometimes even pale green colour, and scratches with difficulty; while the third shews a glistering metallic lustre, and is generally of a brownish or black colour. it scratches easily with the knife, and can be split up into flakes of extreme thinness. if the granite be one of the coarse-grained varieties, we shall notice that these three ingredients have each more or less definite crystalline forms; so that they are not distinguished by colour and hardness alone. the metallic-looking substance is _mica_; the hard gray, or glassy and unscratchable ingredient is _quartz_; and the remaining material is _felspar_. the mineralogist's analysis of granite ends here. but there is still much to be learned about quartz, felspar, and mica; for, as the chemist will tell us, these are not 'elementary substances.' quartz is a compound, consisting of two elements, one of which is a non-metallic body (silicon), and the other an invisible gas (oxygen). felspar[a] is a still more complex compound, being made up of two metals (potassium, aluminium) and one non-metallic body (silicon), each of which is united to an invisible gas (oxygen). mica, again, contains no fewer than four metals (potassium, magnesium, iron, calcium) and one non-metallic body (silicon), each of which is in like manner chemically united to its share of oxygen. thus the rock-forming substances, quartz, felspar, and mica, have each a definite chemical composition. . _minerals._--now, any inorganic substance which has a definite chemical composition, and crystallises in a definite crystalline or geometric form, is termed a _mineral_. having once discovered that quartz is composed of silicon and oxygen--that is, silica--and that the faces of its crystals are arranged in a certain definite order, we may be quite sure that any mineral which has not this composition and form cannot be quartz. and so on with mica and felspar, and every other mineral. the study of the geometric forms assumed by minerals (crystallography) forms a department of the science of mineralogy. but, in the great majority of cases, the mineral ingredients of the rocks are either so small individually, or so broken, and rounded, and altered, that crystallography gives comparatively little aid to the practical geologist in the field. he has, therefore, recourse to other tests for the determination of the mineral constituents of rocks. many of these tests, however, can only be applied by those who have had long experience. the simplest and easiest way for the student to begin is to examine the forms and appearance of the more common minerals in some collection, and thereafter to accustom his eye to the aspect presented by the same minerals when they are associated together in rocks, of which illustrative specimens are now to be met with in most museums. the microscope is largely employed by geologists for determining the mineralogical composition of certain rocks; and, indeed, many rocks can hardly be said to be thoroughly known until they have been sliced and examined under the microscope, and analysed by the chemist. but with a vast number such minute examination is not required, the eye after some practice being able to detect all that is needful to be known. [a] there are various kinds of felspar; the one referred to above is _orthoclase_, or potash-felspar. rock-forming minerals. . nearly all the minerals we know of contain oxygen as a necessary ingredient, there being only a very few minerals in which that gas does not occur in chemical union with other elements. three of these minerals, _sulphur_, the _diamond_, and _graphite_, consist of simple substances, and are of great commercial importance, but none of them is of so frequent occurrence, as a rock constituent, as the minerals presently to be described. _sulphur_ occurs sometimes in thin beds, but more frequently in small nests and nodules, &c. in other rocks, or in joints, and fissures, and veins. it is frequently found in volcanic districts. the _diamond_, which consists of pure _carbon_, is generally met with in alluvial deposits, but sometimes, also, in a curious flexible sandstone, called _itacolumite_. _graphite_ is another form of carbon. it occurs both in a crystalline and amorphous form, the latter, or non-crystalline kind, being extensively used for lead-pencils. _rock-salt_ is a _chloride of sodium_, and appears sometimes in masses of a hundred feet and more in thickness. another mineral which contains no oxygen is the well-known _fluor-spar_. it occurs chiefly in veins, and is often associated with ores. with these, and a few other exceptions, all the minerals hitherto discovered contain oxygen as an essential element; and so large is the proportion of this gas which enters into union with other elements to constitute the various minerals of which the rocks are composed, that it forms at least one-half of all the ponderable matter near the earth's surface. when the student learns that there are probably no fewer than six or seven hundred different minerals, he will understand how impossible it is to do more in a short geological treatise than point out a few of the most commonly occurring ones. and, indeed, a knowledge of the chief rock-forming minerals, which are few in number, is all that is absolutely requisite for geological purposes. some of these we accordingly proceed to name.[b] [b] it is needless to describe the minerals minutely here. the student can only learn to distinguish the different species by carefully examining actual specimens. . _quartz._--this mineral has already been partially described. it is the most abundant of all the rock-forming minerals, and occurs in three forms: ( ) _crystallised quartz_ or _rock crystal_; ( ) _chalcedony_, both of which are composed of silica--that is, silicon and oxygen; and ( ) _hydrated quartz_--that is, silica with the addition of water. _hematite._--this is an oxide of iron. it occurs in mammillary rounded masses, with a fibrous structure, and a dull metallic lustre. _magnetite_ or magnetic iron ore, _specular iron_, and _limonite_ are also oxides of iron. _hematite_ shews a red streak when scratched with a knife, which distinguishes it from magnetite. _iron pyrites._--this is a sulphide of iron of very common occurrence. its crystalline form is cubical. when broken, it emits a sulphurous smell. the brass-yellow coloured cubes so often seen in roofing-slates are familiar examples of the mode of its occurrence. but it is also frequently found in masses having a crystalline surface. . sulphates.--only two sulphates may be noticed--namely, _gypsum_, which is a sulphate of lime, with its varieties, _selenite_, _satin-spar_, and _alabaster_; and _barytes_, a sulphate of baryta. _barytes_ scratches easily with the knife, and from its great specific gravity is often called _heavy-spar_. gypsum is softer than barytes. carbonates.--two of these only need be mentioned: _calcite_ or _calc-spar_, a carbonate of lime, which scratches with the knife, and effervesces readily with dilute hydrochloric acid; and _arragonite_, also a carbonate of lime, but denser than calcite. silicates.--these are by far the most abundantly occurring minerals. the species are also exceedingly numerous, but we may note here only a few of the more important. they are composed of silica and various bases, such as lime, potash, magnesia, soda, alumina, &c. _augite_ or _pyroxene_ is a black or greenish-black mineral, found, either as crystals, which are generally small, or as rounded grains and angular fragments, in basaltic and volcanic rocks. it never occurs in granite rocks. it is brittle, and has a vitreous or resinous lustre. there are a number of varieties or sub-species of augite. _hornblende_, like augite, also includes a great many minerals. when the crystals are small, it is often difficult to distinguish hornblende from augite. common hornblende occurs crystallised or massive, and is dark green or black, with a vitreous lustre. it is generally sub-translucent. it usually crystallises in igneous rocks which contain much quartz or silica; while augite, on the other hand, crystallises in igneous rocks which are of a more basic character--that is to say, rocks in which silica is not so abundantly present. _felspar_ is a generic term which embraces a number of species, such as _orthoclase_ or _potash-felspar_, _albite_ or _soda-felspar_, and _anorthite_ or _lime-felspar_. _orthoclase_ is white, red or pink, and gray. it is one of the ordinary constituents of granite, and enters into the composition of many rocks. _albite_ is usually white. it often occurs as a constituent of granite, not unfrequently being associated in the same rock with pink felspar or orthoclase. in syenite and greenstone it occurs more commonly than orthoclase. _anorthite_ occurs in white translucent or transparent crystals. it is not so common a constituent of rocks as either of the other felspars just referred to. _mica_: this term includes several minerals, which all agree in being highly cleavable into thin elastic flakes or laminæ, which have a glistening metallic lustre. mica is one of the common constituents of granite. _talc_ is a silvery white, grayish, pale or dark-green coloured mineral, with a pearly lustre. it splits readily into thin flakes, which are flexible, but not elastic, and may be readily scratched with the nail. it is unctuous and greasy to the touch. it occurs in beds (_talc-slate_), and is often met with in districts occupied by metamorphic crystalline rocks. _serpentine_ is generally of a green colour, but brown, red, and variously mottled varieties occur. it has a dull lustre, and is soft, and easily cut; it is tough, however, and takes on a good polish. it forms rock-masses in some places. the finer varieties are called _noble serpentine_. _chlorite_ is another soft, easily scratched mineral, generally of a dark-green colour. it has a pearly lustre. sometimes it occurs in beds (_chlorite-slate_), and is often found coating the walls of fissures in certain rocks. it has a somewhat greasy feel. the three last-mentioned minerals--talc, serpentine, and chlorite--are all silicates of magnesia. _zeolites_ is a term which comprises a number of minerals of varying chemical composition, all of which tend to form a jelly when treated with acids. when heated by the blow-pipe they bubble up, owing to the escape of water; hence their name _zeolites_, from _zeo_, i boil, and _lithos_, a stone. the zeolites occur very commonly in cavities in igneous rocks, and also in mineral veins. having now mentioned the chief rock-forming minerals, we proceed to a brief description of some of the more typical representatives of the five great classes of rocks referred to at page . petrology.[c] [c] _petros_, a rock, and _logos_, a discourse. some geologists restrict this term to the study of the _structure_ and _arrangement of rock-masses_, and apply the term _lithology_ (_lithos_, a stone, and _logos_, a discourse) to the study of the _mineralogical composition of rocks_. mechanically formed rocks. . (_a._) sedimentary class.--three of the most commonly occurring rocks of this class have already been described, but a few details are added here. _conglomerate._--this is a consolidated mass of more or less water-worn and rounded stones. these stones may be of any size. when they are very large, the rock is called a _coarse conglomerate_; the finer varieties, in which the stones are small, are known as _pebbly conglomerates_. the ingredients of a conglomerate may consist of any kind of rock, or of a mixture of many different kinds. when they consist entirely of quartz, the rock becomes _quartzose_. the finer-grained conglomerates usually shew lines of deposition or bedding, but in some of the coarser sorts it is often difficult to detect any kind of arrangement. the stones are usually imbedded in a matrix of quartzose grit and sand, but sometimes this is very scanty. when the nature of the material which binds the stones together is very well marked, the rock becomes _ferruginous_, _calcareous_, _arenaceous_, or _argillaceous_, according as the binding or cementing material is _iron_, _lime_, _sand_, or _clay_. _breccia_ is a rock in which the included fragments are _angular_. . _sandstone_ is, as already remarked, merely consolidated sand. the coarser varieties, in which the grains are as large and larger than turnip-seeds, are termed _grit_. from these coarse varieties the rock passes insensibly, in one direction, into a fine or pebbly conglomerate, and in another into a rock, so fine-grained that a lens is needed to distinguish the component particles. quartz is the prevailing ingredient--sometimes clear, at other times white. frequently, however, the grains are coated with an oxide of iron, which gives the resulting rock a red colour. the other colours assumed by sandstone--such as yellow, brown, green, &c.--are also in like manner due to the presence of some compound of iron. when mica or felspar occurs plentifully, we have, in the one case, _micaceous sandstone_, and in the other _felspathic sandstone_. a sandstone in which the grains are cemented by carbonate of lime is said to be _calcareous_. _freestone_ is a sandstone which can be worked freely in any direction. in most sandstones, the lines of bedding are distinct; when they are so numerous as to render the rock fissile, the sandstone is said to be _shaly_. _shale_ is a more or less indurated fissile or laminated clay. when the rock becomes coarse by the admixture of sand, it gradually passes into a _shaly sandstone_. there are many other varieties of clay-rocks--such as _fire-clay_, _pipe-clay_, _marl_, _loam_, &c.--which are sufficiently familiar. . (_b._) eolian or aËrial class.--_blown-sand_ is found at many places on sea-coasts. it generally forms smooth rounded hummocks, which are sometimes arranged in long lines parallel to the trend of the coast, as, for example, in the tents moor, near st andrews. the _sand-hills_ of deserts also belong to this class. _débris_ is the loose angular rubbish which collects at the base of cliffs, on hill-tops, and hill-slopes. immense accumulations of it occur in lofty mountainous districts and in arctic regions. in nova zembla, for example, the solid rock of the country is almost concealed beneath a thick covering of débris. but the various kinds of débris will be more particularly described further on. _soil._--an account of this can hardly be given without entering into the theory of its origin, and therefore we reserve its consideration for the present. chemically formed rocks. . _stalactites_ and _stalagmites_ are carbonates of lime. they vary in colour, being white, or yellow, or brown. stalactites are usually found adhering to the roofs of limestone caverns, &c., or depending from limestone rocks; stalagmites, on the other hand, commonly occur on the floors of limestone caverns, where they often attain a thickness of many feet. _siliceous sinter_ is silica with the addition of water--in other words, a hydrated quartz. it is not a very abundant rock, and is found chiefly in volcanic countries. _rock-salt_ has already been described. it occurs either as thin beds, or in the form of thick cake-like masses, often reaching ninety or one hundred feet in thickness. it is rudely crystalline in texture, and is usually discoloured brown and red with various impurities. organically derived rocks. . _limestone_ consists of carbonate of lime, but usually contains some impurities. the varieties of this rock are numerous; some of them are as follows: _chalk_; _oolite_, a rock built up of little spheroidal concretions, whence its name, _egg_ or _roe stone_ (the coarser oolites are called _pisolite_, or _pea-stone_); _lacustrine limestone_, &c. when much silica is diffused through the rock, we have a _siliceous limestone_; the presence of clay and of carbonaceous matter gives us _argillaceous_ and _carbonaceous limestones_. _cornstone_ is a limestone containing a large quantity of arenaceous matter or sand. many limestones are distinguished by the different kinds of organic remains which they yield. thus, we have _muschelkalk_ or _shell-limestone_, _nummulitic_, _crinoidal_, &c. limestone. the crystalline limestones, such as _statuary marble_, are metamorphosed limestones. not a few limestones are chemically formed rocks, and many, also, are partly of chemical and partly of organic origin, so that no hard and fast line can be drawn between these two classes of rock. _dolomite_, or _magnesian limestone_.--this is a compound of carbonate of lime and carbonate of magnesia. its colour is usually yellow, or yellowish brown, but gray and black varieties are sometimes met with. it is generally fine-grained, with a crystalline texture, and pearly lustre. it effervesces less freely with acids than pure limestone. in many cases dolomite is merely a metamorphosed limestone. . _coal_ is composed of vegetable matter, but usually contains a greater or less percentage of impurities. the varieties of this substance are very numerous, and differ from each other principally in regard to their bituminous or non-bituminous character. coal is bituminous or non-bituminous according as it is less or more highly mineralised. bitumen results from the decomposition of vegetable matter; but, when the mineralising process (to which the formation of coal is due) has proceeded far enough, the vegetable matter gradually loses its bituminous character, and the result is a non-bituminous coal. varieties of coal are the following: _lignite_ or _brown coal_; _caking coal_; _cannel_, _parrot_, or _gas coal_; _splint coal_; _cherry_ or _soft coal_; _anthracite_ or _blind coal_, so called because it burns with no flame. _peat_ may be mentioned as another natural fuel. it is composed of vegetable matter. in some kinds it is so far decomposed, or mineralised, that the eye does not detect vegetable fibres; when thoroughly dried, such peat breaks like a good lignite, and forms an excellent fuel. metamorphic rocks. . _quartz-rock_, or _quartzite_, is an altered quartzose sandstone or grit; it is generally a white or grayish-yellow rock, very hard and compact. the original gritty character of the rock is distinct, but the granules appear as if they had been fused so far as to become mutually adherent. when the altered sandstone has been composed of grains of quartz, felspar, or mica, set in a siliceous, felspathic, or argillaceous base, we get a rock called _greywacké_, which is usually gray or grayish blue in colour. . _clay-slate_ is a grayish blue, or green, fine-grained hard rock, which splits into numerous more or less thin laminæ, which may or may not coincide with the original bedding. most usually the 'cleavage,' as this fissile structure is termed, crosses the bedding at all angles. . _crystalline limestone_ is an altered condition of common limestone. _saccharoid marble_ is one of the fine varieties: it frequently contains flakes of mica. _dolomite_, or magnesian limestone, already described, is probably in many cases an altered limestone; the carbonate of lime having been partially dissolved out and replaced by carbonate of magnesia. _serpentine_ is also believed by some geologists to be a highly metamorphosed magnesian limestone. . _schists_.--under this term comes a great variety of crystalline rocks which all agree in having a foliated texture--that is to say, the constituent minerals are arranged in layers which usually, but not invariably, coincide with the original bedding. amongst the schists come _mica-schist_ (quartz and mica in alternate layers); _chlorite-schist_ (chlorite with a little quartz, and sometimes with felspar or mica); _talc-schist_ (talc with quartz or felspar); _hornblende schist_ (hornblende with a variable quantity of felspar, and sometimes a little quartz); _gneiss_ (quartz, felspar, and mica). . _general character of metamorphic rocks._--all these rocks betray their aqueous origin by the presence of more or less distinct lines of bedding. they consist of various kinds of arenaceous and argillaceous deposits, which, under the influence of certain metamorphic actions, to be described in the sequel, have lost their original granular texture, and become more or less distinctly crystallised. and not only so, but their chemical ingredients have in many cases entered into new relations, so as to give rise to minerals which existed either sparingly or not at all in the original rocks. frequently, it is quite impossible to say what was the original condition of some metamorphic rocks; often, however, this is sufficiently obvious. thus, highly micaceous sandstones, as they are traced into a metamorphic region, are seen to pass gradually into mica-schist. when the bedding of gneiss becomes entirely obliterated, it is often difficult to distinguish that rock from granite, and in many cases it appears to pass into a true granite. . _granite_ is a crystalline compound of quartz, felspar (usually potash-felspar), and mica. some geologists consider it to be invariably an igneous rock; but, as just stated, it sometimes passes into gneiss in such a way as to lead us to infer its metamorphic origin. there are certain areas of sandstone in the south of scotland which are partially metamorphosed, and in these we may trace a gradual passage from highly baked felspathic sandstones with a sub-crystalline texture into a more crystalline rock which in places graduates into true granite. granite, however, also occurs as an igneous rock. . _syenite_ is a crystalline compound of a potash-felspar and hornblende, and quartz is frequently present. _diorite_ is a crystalline aggregate of a soda-felspar and hornblende. both syenite and diorite also occur as igneous rocks. there are a number of other metamorphic rocks, but those mentioned are the most commonly occurring species. igneous rocks. . _subdivisions._--in their chemical and mineralogical composition, igneous rocks offer great variety; but they all agree in having felspar for their base. they may be roughly divided into two classes, distinguished by the relative quantity of silica which they contain. those in which the silica ranges from about to or per cent. form what is termed the _acidic_ group; while those in which the percentage of silica is less constitute the _basic_ group of igneous rocks, so called because they contain a large proportion of the heavier bases, such as _magnesia_, _lime_, oxides of iron and manganese, &c. igneous rocks vary in texture from homogeneous, compact, and finely crystalline masses up to coarsely crystalline aggregates, in which the crystals may be more than an inch in diameter. sometimes they are dull and earthy in texture, at other times vesicular. when the vesicles are filled up with some mineral, the rock is said to be _amygdaloidal_, from the almond shape assumed by the kernels filling the cavities. when single crystals of any mineral are scattered through a rock, so as to be readily distinguished from the compact or crystalline base, the rock becomes _porphyritic_. acidic or felspathic group. . _trachyte_ (_trachys_, rough) is a pale or dark-gray rock, harsh and rough to the touch, in which felspar is the predominant mineral. it is a common product of eruption in modern volcanoes. _clinkstone_ or _phonolite_ is a greenish-gray, compact, felspathic rock, somewhat slaty or schistose, and weathers with a white crust. it gives a clear metallic sound under the hammer. it is a rock not met with among the older formations of the earth's crust, being confined to tertiary (see table, p. ) or still more recent times. _obsidian_ or _volcanic glass_ is usually black, brown, or green, and usually resembles a coarse bottle-glass. when it becomes vesicular, it passes gradually into the highly porous rock called _pumice_. it is eminently a geologically modern volcanic rock. _felstone_ is a reddish-gray, bluish, greenish, or yellowish, hard, compact, flinty-looking rock, composed of potash-felspar and silica. it is generally splintery under the hammer. some varieties are slaty, and are frequently mistaken for clinkstone, which they closely resemble. when the quartz in felstone is distinctly visible either as grains or crystals, the rock passes into a _quartz-porphyry_. _granite_ is recognised as an igneous as well as a metamorphic rock. sometimes the veins and dykes which proceed from or occur near a mass of granite contain no mica--this kind of rock is called _elvan_ or _elvanite_. _porphyrite_ or _felspathite_ includes a number of rocks which have a felspathic base, through which felspar crystals are scattered more or less abundantly. sometimes hornblende, or augite, or mica is present. the colour is usually dark--some shade of blue, green, red, puce, purple, or brown--and the texture varies from compact and finely crystalline up to coarsely crystalline. porphyrites are usually porphyritic, and frequently amygdaloidal. augitic and hornblendic or basic group. . _basalt_ is a dark or almost black compact homogeneous rock, composed of felspar and augite with magnetic iron. an olive-green mineral called _olivine_ is very frequently present. the coarser-grained basalts are called _dolerite_. the columnar structure is not peculiarly characteristic of basalt. many basalts are not columnar, and not a few columnar rocks are not basalts. _greenstone_ or _diorite_ is usually a dull greenish rock, sometimes gray, however, speckled with green. it is composed of soda-felspar and hornblende. the fine-grained compact greenstones are called _aphanite_. _syenite_, like granite, is recognised as an igneous as well as a metamorphic rock. there are several other rocks which come into the basic group, but those mentioned are the more common and typical species. . _fragmental igneous rocks._--all the igneous rocks briefly described above are more or less distinctly crystalline in texture. there is a class of igneous rocks, however, which do not present this character, but when fine-grained are dull and earthy in texture, and frequently consist merely of a rude agglomeration of rough angular fragments of various rocks. these form the fragmental group of igneous rocks. the ejectamenta of loose materials which are thrown out during a volcanic eruption, consist in chief measure of fragments of lava, &c. of all sizes, from mere dust, sand, and grit, up to blocks of more than a ton in weight. these materials, as we shall afterwards see, are scattered round the orifice of eruption in more or less irregular beds. the terms applied to the varieties of ejectamenta found among modern volcanic accumulations, will be given and explained when we come to consider the nature of geological agencies. in the british islands, and many other non-volcanic regions, we find besides crystalline igneous rocks, abundant traces of loose ejectamenta, which clearly prove the former presence of volcanoes. these materials are sometimes quite amorphous--that is to say, they shew no trace of water action--they have not been spread out in layers, but consist of rude tumultuous accumulations of angular and subangular fragments of igneous rocks. such masses are termed _trappean agglomerate_ and _trappean breccia_. at other times, however, the ejectamenta give evidence of having been arranged by the action of water, the materials having been sifted and spread out in more or less regular layers. what were formerly rude breccias and agglomerates of angular stones now become _trappean conglomerates_--the stones having been rounded and water-worn--while the fine ingredients, the grit, and sand, and mud, form the rock called _trap tuff_. fragmental rocks are often quite indurated--the matrix being as hard as the included stones. but as a rule they are less hard than crystalline igneous rocks, and in many cases are loose and crumbling. when a fragmental rock is composed chiefly of rocks belonging to the acidic group, we say it is _felspathic_. when augitic and hornblendic materials predominate, then other terms are used; as, for example, _dolerite tuff_, _greenstone tuff_. structure and arrangement of rock-masses. . the student can hardly learn much about the mineralogical composition of rocks, without at the same time acquiring some knowledge of the manner of their occurrence in nature. we have already briefly described certain sedimentary rocks, such as conglomerate, sandstone, and shale, and have in some measure touched upon their structure as rock-masses. these rocks, as we have seen, are arranged in more or less thick layers or _beds_, which are piled one on the top of the other. rocks which are so arranged are said to be _stratified_, and are termed _strata_. we may also use the word _stratum_ as an occasional substitute for _bed_. the planes of _bedding_ or _stratification_ are sometimes very close together, in other cases they are wide apart. when the separate beds are very thin, as in the case of shale, it is most usual to term them _laminæ_, and to speak of the _lamination_ of a shale, as distinguished from the _bedding_ of a sandstone. planes of bedding are generally more strongly marked than planes of lamination. the laminæ frequently cohere, while beds seldom do. in the above figure, which represents a vertical cutting or _section_ through horizontal strata, the planes of lamination are shewn at _l, l, l_, and those of stratification at _s, s, s_. there are hardly any limits to the thickness of a bed--it may range from an inch up to many feet or yards, while _laminæ_ vary in thickness from an inch downwards. [illustration: fig. .--_st_, sandstone, and _sh_, shale: _s_, lines or planes of bedding; _l_, lines or planes of lamination.] . hitherto we have been considering the _laminæ_ and _strata_ as lying in an approximately horizontal plane. sometimes, however, the layers of deposition in a single stratum are inclined at various angles to themselves, as in the following figure. this structure is called _false bedding_; the layers or laminæ not coinciding with the planes of stratification. it owes its origin to shifting currents, such as the ebb and flow of the tide, and very often characterises deposits which have been formed in shallow water. (hillocks of drifting sand frequently shew a similar structure, but their false bedding is, as a rule, much more pronounced.) [illustration: fig. .--false bedding.] . _mud-cracks and rain-prints._--the surfaces of some beds occasionally exhibit markings closely resembling those seen upon a flat sandy beach after the retreat of the tide--hence they are called _ripple-marks_ or _current-marks_. they are, of course, due to the gentle current action which pushes along the grains of sand, and hence, such marks may be formed wherever a current sweeps over the bottom of the sea with energy just sufficient for the purpose. but since the necessary conditions for the formation of _ripple-mark_ occur most abundantly in shallow water, its frequent appearance in a series of strata may often be taken as evidence, so far, for the shallow-water origin of the beds. besides ripple-marks we may also detect occasionally on the surfaces of certain strata _mud-cracks_ and _rain-prints_. these occur most commonly in fine-grained beds, as in flagstones, argillaceous sandstones, shales, &c. the _mud-cracks_ resemble those upon a mud-flat which are caused by the desiccation and consequent shrinkage of the mud when exposed to the sun. the old cracks have been subsequently filled up again by a deposition of mud or sand, usually of harder consistency than the rock traversed by the cracks. hence, when the bed that overlies the mud-cracks is removed, we find a cast of these projecting from its under surface, or frequently the cast remains in its mould, and forms a series of curious ridges ramifying over the whole surface of the old mud-flat. _rain-prints_ are the small pits caused by the impact of large drops. they are usually deeper at one side than the other, from which we can infer the direction of the wind at the time the rain-drops fell. like the mud-cracks, they are most commonly met with in fine-grained beds, and have been preserved in a similar manner. some geologists have also been able to detect _wave-marks_, 'faint outlinings of curved form on a sandstone layer, like the outline left by a wave along the limit where it dies out upon a beach.' . _succession of strata._--the succession of strata is often very diversified. thus, we may observe in one and the same section numberless alternating beds of sandstone and shale from an inch or so up to several feet each in thickness, with seams of coal, fireclay, ironstone, and limestone interstratified among them. in other cases, again, the succession is simpler, and some deep quarries shew only one bed, as is the case with certain limestones, fine-grained sandstones (liver-rock), and many volcanic rocks. some limestones, indeed, shew small trace of bedding throughout a vertical thickness of hundreds of feet. . _beds, their extent, &c._--beds of rock are not only of very different thicknesses, but they are also of very variable extent. some may thin gradually away, or 'die out' suddenly, in a few feet or yards, while others may extend over many square miles. beds of limestone, for example, can often be traced for leagues in several directions; and if this be the case with certain single beds, it is still more true of groups of strata. thus the coal-bearing strata belonging to what is called the carboniferous period cover large areas in wales, england, scotland, and ireland, not less, probably, than square miles; and strata belonging to the same great period spread over considerable tracts on the continent, and a very extensive area in north america. it holds generally true that beds of fine-grained materials are not only of more equal thickness throughout, but have also a wider extension than coarser-grained rocks. fine sandstones, for example, extend over a wider area, and preserve a more equable thickness throughout than conglomerates, while limestones and coals are more continuous than either. . when a bed is followed for any distance it is frequently found to thin away, and give place to another occupying the same plane or _horizon_. thus a shale will be replaced by a sandstone, a sandstone by a conglomerate, and _vice versâ_. sometimes also we may find a shale, as we trace it in some particular direction, gradually becoming charged with calcareous matter, so as by and by to pass, as it were, into limestone. every bed must, of course, end somewhere, either by thus gradually passing into another, or by thinning out so as to allow beds which immediately overlie and underlie it to come together. not unfrequently, however, a bed will stop abruptly, as in fig. . [illustration: fig. .--sudden ending of bed at ×.] . _sequence of beds._--it requires little reflection to see that the division plane between two beds may represent a very long period of time. let the following diagram represent a section of strata, _s_ being beds of grit, and _a_, _b_, _c_, beds of sandstone and shale. it is evident that the beds s must have been formed before the strata _b_ were deposited above them. at ×, the beds _a_ and _b_ come together, and were attention to be confined to that part of the section, the observer might be led to infer that no great space of time elapsed between the deposition of these two beds. yet we see that an interval sufficient to allow of the formation of the beds _s_ must really have intervened. it is now well known that in many cases planes of bedding represent 'breaks in the succession' of strata--'breaks' which are often the equivalents of considerable thicknesses of strata. in one place, for example, we may have an apparently complete sequence of beds, as _a_, _b_, _c_, which a more extended knowledge of the same beds, as these are developed in some other locality, enables us to supplement, as _a_, _s_, _b_, _c_. [illustration: fig. .--sequence of beds.] . _joints._--besides _planes_ or _lines of bedding_, there are certain other division planes or _joints_ by which rocks are intersected. the former, as we have seen, are congenital; the latter are subsequent. joints cut right across the bedding, and are often variously combined, one set of joint planes traversing the rock in one direction, and another set or sets intersecting these at various angles. thus, in many cases the rocks are so divided as easily to separate into more or less irregular fragments of various sizes. besides these confused joints there are usually other more regular division planes, which intersect the strata in some definite directions, and run parallel to each other, often over a wide area: these are called _master-joints_. two sets of master-joints may intersect the same strata, and when such is the case, the rock may be quarried in cuboidal blocks, the size of which will vary, of course, according as the two sets of joints are near or wide apart. joints may either gape or be quite close; so close, indeed, as in many cases to be invisible to the naked eye. certain igneous rocks frequently shew division planes which meet each other in such a way as to form a series of polygonal prisms. the basalt of staffa and giants' causeway are familiar examples of this structure. jointing is due to the gradual consolidation of the strata, and hence, in a series of strata, we may find the separate beds, according to their composition, very variously affected, some being much more abundantly jointed than others. master-joints which traverse a wide district in some definite direction probably owe their origin to tension, the strata having been subjected to some strain by the underground forces. [illustration: fig. .--beds of limestone (_a_), sandstone (_b_), and shale (_c_), divided into cuboidal masses by master-joints.] [illustration: fig. .--columnar structure.] [illustration: fig. .--bedding, joints, and cleavage (after murchison).] . _cleavage._--fine-grained rocks, more especially those which are argillaceous, occasionally shew another kind of structure, which is called _cleavage_. common clay-slate is a type of the structure. this rock splits up into innumerable thin laminæ or plates, the surface of which may either be somewhat rough, or as smooth nearly as glass. the cleavage planes, however, need not be parallel with the planes of bedding; in most cases, indeed, they cut right across these, and continue parallel to each other often over a very wide region. the original bedding is sometimes entirely obliterated, and in most cases of well-defined cleavage is always more or less obscure. in the preceding diagram, the general phenomena of _bedding_, _jointing_, and _cleavage_ are represented. the lines of bedding are shewn at s, s; another set of division-planes (joints) is observed at j, j, intersecting the former at right angles--a, b, c being the exposed faces of joints. the lines of cleavage are seen at d, d, cutting across the planes of bedding and jointing. . _foliation_ is another kind of superinduced structure. in a foliated rock the mineral ingredients have been crystallised and arranged in layers along either the planes of original bedding or those of cleavage. mica-schist and gneiss are typical examples. . _concretions._--in many rocks a concretionary structure may be observed. some sandstones and shales appear as if made up of spheroidal masses, the mineral composition of the spheroids not differing apparently from that of the unchanged rock. so in some kinds of limestone, as in _dolomite_, the concretionary structure is often highly developed, the rock resembling now irregular heaps of turnips with finger-and-toe disease, again, piles of cannon-balls, or bunches of grapes, and agglomerations of musket-shot. a spheroidal structure is occasionally met with amongst some igneous rocks. this is well seen in the case of rocks having the basaltic structure, in which the pillars, being jointed transversely, decompose along their division planes, so as to form irregular globular masses. in many cases, certain mineral matter which was originally diffused through a rock has segregated so as to form nodules and irregular layers. examples of this are _chert_ nodules in limestone; _flint_ nodules in chalk; _clay-ironstone_ balls in shale, &c. [illustration: fig. .--dip and strike of strata.] . _inclination of strata._--beds of aqueous strata must have been deposited in horizontal or approximately horizontal planes; but we now find them most frequently inclined at various angles to the horizon, and often even standing on end. they sometimes, however, retain a horizontal position over a large tract of country. the angle which the inclined strata make with the horizon is called the _dip_, the degree of inclination being the _amount_ of the dip; and a line drawn at right angles to the dip is called the _strike_ of the beds. thus, a bed dipping south-west will have a north-west and south-east strike. the _crop_ or _outcrop_ (sometimes also, but rarely, called the _basset edge_) of a bed is the place where the edge of the stratum comes to view at the surface. we may look upon inclined beds as being merely parts of more or less extensive undulations of strata, the tops of the undulations having been removed so as to expose the truncated edges of the beds. in the following diagram, for example, the outcrops of limestone seen at _l_, _l_, are evidently portions of one and the same stratum, the dotted lines indicating its former extent. the trough-shaped arrangement of the beds at _s_ is called a _synclinal curve_, or simply a syncline; the arched strata at _a_ forming, on the contrary, an _anticlinal curve_ or _anticline_. [illustration: fig. .--anticlines and synclines.] [illustration: fig. .--contorted strata.] when strata shew many and rapid curves, they are said to be contorted. the diagram section (fig. ) will best explain what is meant by this kind of structure. . in certain regions, the strata often dip in one and the same direction for many miles, at an angle approaching verticality, as in the following section. it might be inferred, therefore, that from a to b we had a gradually ascending series--that as we paced over the outcrop we were stepping constantly from a lower to a higher geological horizon. but, in such cases, the dip is deceptive, the same beds being repeated again and again in a series of great foldings of the strata. such is the case over wide areas in the upland districts of the south of scotland. the section (fig. ) shews that the beds are actually inverted, the strata at × × being bent back upon strata which really overlie them. [illustration: fig. .--inversion of strata.] [illustration: fig. .--contemporaneous erosion.] . _contemporaneous erosion._--occasionally a group of strata gives proof that pauses in the deposition of sediment took place, during which running water scooped out of the sediment channels of greater or less width, which subsequently became filled up with similar or dissimilar materials. the diagram (fig. ) will render this plain. at _a_ we have beds of sandstone, which it is evident were at one time throughout as thick as they still are at × ×. having been worn away to the extent indicated, a deposition of clay (_b_) succeeded; and this, in turn, became eroded at _c_, _c_, the hollows being filled up again with coarse sand and gravel. in former paragraphs, we found reason to believe that lines of bedding indicated certain pauses in the deposition of strata. here, in the present case, we have more ample proof in the same direction. [illustration: fig. .--unconformability.] . _unconformability._--but the most striking evidence of such pauses in the deposition of strata is afforded by the phenomenon called _unconformability_. when one set of rocks is found resting on the upturned edges of a lower set, the former are said to be _unconformable_ to the latter. in the above section (fig. ), _a_, _a_, are beds of sandstone resting on the upturned edges of beds of limestone, shale, and sandstone, _l_, _s_. figs. and give other examples of the same appearance. it is evident that, in the case of fig. , the discordant bedding chronicles the lapse of a very long period. we have to conceive first of the deposition of the underlying strata in horizontal or approximately horizontal layers; then we have to think of the time when they were crumpled up into great convolutions, and the tops of the convolutions (the anticlines) were planed away: all these changes intervened, of course, after the lower set was deposited, and before the upper series was laid down. in the case represented in fig. , we have a double unconformability, implying a still more elaborate series of changes, and probably, therefore, a still longer lapse of time. [illustration: fig. .--violent unconformability.] [illustration: fig. .--double unconformability.] . _overlap._--when the upper beds of a conformable group of strata spread over a wider area than the lower members of the same series, they are said to _overlap_. the accompanying diagram shews this appearance. an overlap proves that a gradual submergence of the land was going on at the time the strata were being accumulated. as the land disappeared below the water, the sediment gradually spread over a wider area, the more recently deposited sediment being laid down in places which existed as dry land at the time when the earliest accumulations were formed. thus, in the accompanying illustration (fig. ), the stratum marked , resting unconformably upon older strata, is overlapped by , as that is by , and so on--all the beds in succession coming to repose upon the older strata at higher and higher levels, as the old land subsided. [illustration: fig. .--overlap.] [illustration: fig. .--fault.] . _dislocations or faults._--when strata, once continuous, have been broken across, and displaced or shifted along the line of breakage, they are said to be _faulted_, the fissure along which the displacement occurs being termed a _fault_ or _dislocation_. the simplest form of a fault is that shewn in the following diagram, where strata of sandstone and shale, with a coal-seam, s, have been shifted along the line _f_. the direction in which the _fault_ is inclined[d] is its _hade_, and the degree of _vertical displacement_ of the beds is the _amount_ of the dislocation. generally, the beds seem to be pulled _down_ in the direction of the _downthrow_, and _drawn up_ on the opposite side of the fault, as shewn in the diagram. sometimes the rocks on each side of a fault are smoothed and polished, and covered with long scratches, as if the two sides of the fissure had been rubbed together. this is the appearance called _slickensides_. slickensides, however, may occur on the walls of a fissure which is not a displacement, but a mere joint or crack. a dislocation is spoken of as a downthrow or an upcast, according to the direction in which it is approached. thus, a miner working along the coal-seam s, from _a_ to _b_, would describe the fault, _f_, as an _upcast_, since he would have to mine to a _higher_ level to catch his coal again. but, had he approached the fault from _c_ to _d_, he would then have termed it a _downthrow_, because he would see from the hade of the fault that his coal-seam must be sought for at a _lower_ level. faults are of all sizes, from a foot or two up to vertical displacements of thousands of feet. powerful dislocations can often be followed for many miles across a country, running in a more or less linear direction. thus, one large fault has been traced across the breadth of scotland, from near st abb's head, in the east, to the coast of wigtown, in the west. every large throw is accompanied by a number of smaller ones--some of which run parallel to the main fault, while many others seem to run out from this at various angles. faults are of all geological ages. some date back to a most remote antiquity, others are of quite recent origin; and no doubt faults are occurring even now. in the following diagram, the strata, _a, a_, have been faulted and planed away before the strata, _b_, were deposited. hence, in this case, it is evident that if we know the geological age of the beds, _a_ and _b_, we can have an approximation to the age of the fault. if the beds, _a_, be carboniferous, and those at _b_ permian, then we should say the fault was _post-carboniferous_ or _pre-permian_. [d] the degree of inclination is very variable. it may occur at almost any angle up to vertical. but, as a rule, the hade of the more powerful faults is steeper than that of minor displacements. [illustration: fig. .--ground-plan of large main fault and minor displacement fissures.] [illustration: fig. .--faulted strata covered by undisturbed strata.] . _metamorphic and igneous rocks--mode of their occurrence._--in the foregoing remarks on the structure and arrangement of rocks we have had reference chiefly to the aqueous strata--that is to say, the _mechanically_, _chemically_, and _organically_ formed rocks. we were necessarily compelled, however, to make some reference to, and to give some description of, certain structures and arrangements which are not peculiar to aqueous strata, but characterise many metamorphic and igneous rocks as well. to avoid repetition it was also necessary, while treating of _joints_, &c., to give some account of certain structures which are the result of metamorphic action. but, for sake of clearness, we have reserved special account of the structure and mode of occurrence of metamorphic and igneous rocks to this place. after what has been said as to the structure and arrangement of aqueous strata, it is hardly needful to say much about the crystalline schists. these the student will understand to be merely highly altered aqueous rocks,[e] in which the marks of their origin are still more or less distinctly traceable. as a rule, metamorphic strata are contorted, twisted, and crumpled, although here and there comparatively horizontal stretches of altered rocks may be observed. the regions in which they occur are often hilly and mountainous, but this is by no means invariably the case. the greater part of the mountainous regions of the british islands is occupied by rocks which are more or less altered; the more crystalline rocks, such as mica-schist, gneiss, &c., being abundantly developed in the scottish highlands, and in the north and west of ireland; while those which are less altered cover large areas in the south of scotland, and in wales and the north-west of england. throughout these wide areas the rocks generally dip at high angles, and contortion and crumpling are of common occurrence. the finer-grained clay-rocks also exhibit fine cleavage planes, and are in some places quarried for roofing-slates--the welsh quarries being the most famous. here and there, bedding is entirely effaced, and the resulting rock is quite amorphous, and, becoming gradually more and more crystalline, passes at last into a rock which in many cases is true granite. the original strata have disappeared, and granite occupies their place, in such a way as to lead to the inference that the granite is merely the aqueous strata which have been fused up, as it were, _in situ_. at other times the granite would appear to have been erupted amongst the aqueous strata, for these are highly confused, and baked, as it were, at their junction with the granite, from which, also, long veins are seen protruding into the surrounding beds. metamorphic granite, then, graduates, as a rule, almost imperceptibly into rocks which are clearly of aqueous origin; while on the contrary the junction-line between igneous granite and the surrounding rocks is always well marked. the origin of granite, however, is a difficult question, and one which has given rise to much discussion. some further remarks upon the subject will be found in the sequel under the heading of _metamorphism_. [e] igneous rocks have also in some cases undergone considerable alteration; fine-grained tuffs, for example, occasionally assume a crystalline texture. . true _igneous rocks_ occur either in beds or as irregular amorphous masses. when they occur as beds interstratified with aqueous strata, they are said to be _contemporaneous_, because they have evidently been erupted at the time the series of strata among which they appear was being amassed. when, on the other hand, they cut across the bedding, they are said to be _subsequent_ or _intrusive_, because in this case they have been formed at a period _subsequent_ to the strata among which they have been _intruded_. the bed upon which a contemporaneous igneous rock reclines, often affords marks of having been subjected to the action of heat; sandstones being hardened, and frequently much jointed and cracked, owing to the shrinking induced by the heat of the once molten rock above, and clay-rocks often assuming a baked appearance. there is generally, also, some discoloration both in the pavement of rock upon which the igneous mass lies, and in the under portions of the latter itself. the beds overlying a contemporaneous igneous rock, however, do not exhibit any marks of the action of heat; the old lava-stream having cooled before the sediment, now forming the overlying strata, was accumulated over its surface. one may often notice how the sand and mud have quietly settled down into the irregular hollows and crevices of the old lava, as in the following section, where _i_ represents the igneous rock; _a_ being the baked pavement of sandstone, &c.; and _b_ the overlying sedimentary deposits. when the igneous rock itself is examined, its upper portions are often observed to be scoriaceous or cinder-like, and the under portions likewise frequently exhibit a similar appearance. it is generally most solid towards the centre of the bed. the vesicles, or pores, in the upper and lower portions are often flattened, and are frequently filled with mineral matter. sometimes these cavities may have been filled at the time the rock was being erupted, but in most cases the mineral matter would appear to have been introduced subsequently by the action of water percolating through the rock. occasionally we meet with igneous rocks which are more or less vesicular and amygdaloidal throughout their entire mass. others, again, often shew no vesicular structure, but are homogeneous from top to bottom. the texture is also very variable, and this even in the same rock-mass; some portions being compact or fine-grained, and others coarsely crystalline. as a rule the rock is most crystalline towards the centre, and gets finer-grained as the top and bottom of the bed are approached. not unfrequently, however, an igneous rock will preserve the same texture throughout. the jointing is also highly irregular as a rule. but in many cases, especially when the rock is fine-grained, the jointing is very regular. the basaltic columns of the giants' causeway and the isle of staffa are well-known examples of such regularly jointed masses. igneous rocks frequently decompose into a loose earthy mass (_wacké_), and this is most markedly the case with those belonging to the basic group. [illustration: fig. .--contemporaneous igneous rock.] . contemporaneous igneous rocks are frequently associated with more or less regular beds of _breccia_, _conglomerate_, _ash_, _tuff_, &c. these are evidently the loose volcanic ejectamenta which accompanied former eruptions of lava, and have been arranged by the action of water. beds of such materials, however, frequently occur without any accompanying lava-form rocks. nor are they always arranged in bedded masses. they sometimes appear filling vertical pipes which seem to have been the funnels of old volcanoes. the following section exhibits the general appearance of one of these volcanic _necks_. they are very common in some parts of scotland, as in ayrshire, and are frequently ranged along the line of a fault in the strata. fig. shews such a neck of ejectamenta, made up of fragments of various kinds of rock, such as sandstone, shale, limestone, coal, &c., sometimes without any admixture of igneous rocks. the strata through which the pipe has been pierced usually dip in towards the latter, and at their junction with the coarse agglomerate often shew marks of the action of heat, coal-seams having sometimes been 'burned' useless for a number of yards away from the 'neck.' [illustration: fig. .--neck filled with volcanic agglomerate.] . intrusive igneous rocks occur as _sheets_, _dykes_, and _necks_. the sheets frequently conform for long distances to the bedding of the strata among which they occur, and are thus liable to be mistaken for contemporaneous rocks. but when they are closely examined, it will be seen that they not only bake or alter the beds above and below them, but seldom keep precisely to one horizon or level--occasionally rising to a higher, or sinking to a lower position in the strata, as shewn in the following diagram-section. dykes are wall-like masses of igneous strata which cut across the strata, generally at a high angle (see _d, d_, fig. ). in the neighbourhood of a recent volcanic orifice, numerous dykes are seen ramifying in all directions. in the british islands some dykes have been followed in a linear direction for very long distances. sometimes these occupy the sites of large dislocations, at other times they have cut through the strata without displacing them. occasionally they appear to have been the feeders of the great sheets of igneous rock which here and there occur in their vicinity. the phenomena presented by the _necks_ of intrusive rock do not differ from those characteristic of _agglomerate_ or _tuff necks_. the strata are bent down towards the central plug of igneous rock, and are generally more or less altered at the line of junction. [illustration: fig. .--intrusive sheet and dykes: _i_, igneous intrusive sheet; _d_, _d_, dykes; _s_, _s_, sedimentary strata.] . intrusive rocks offer, as a rule, some contrasts in texture to contemporaneous masses. they are seldom amygdaloidal, but when they are so it is generally towards the centre of the mass. the kernels are usually minute and more or less spherical. [illustration: fig. .--contemporaneous and intrusive igneous rocks: _c_, _c_, contemporaneous trap-rocks[ ]; _t_, _t_, contemporaneous fragmental igneous rocks; _i_, _p_, _n_, _d_, intrusive igneous rocks.] the diagram (fig. ) shews the general mode of occurrence of igneous rocks on the large scale. the stratified aqueous deposits are indicated at _a_, _a_. these are overlaid by a series of alternating beds of crystalline (_c_) and fragmental (_t_) igneous rocks. an irregular intrusive sheet at _i_ cuts across the beds _a_, _a_. at _p_, another intrusive mass is seen rising in a pipe, as it were, and overflowing the beds _a_, _a_, so as to form a cap. a volcanic neck filled with angular stones intersects the strata at _n_, and two dykes, approaching the vertical, traverse the bedded rocks at _d_, _d_. it will be noticed that the contemporaneous igneous rocks form a series of escarpments rising one above the other. the alteration effected by igneous rocks is generally greatest in the case of intrusive masses. this is well seen in some of our coal-fields, where the coal has frequently been destroyed over large areas by the proximity of masses of what was once melted rock. it is curious to notice how the intrusive sheets in a great series of strata have forced their way along the lines of least resistance. thus, in the scottish coal-fields, we find again and again that intrusive sheets have been squirted along the planes occupied by coal-seams, these having been more easily attacked than beds of sandstone or shale. the coal in such cases is either entirely 'eaten up,' as it were, or converted into a black soot. at other times, however, it is changed into a kind of coke, while other seams at a greater distance from the intrusive mass have been altered into a kind of 'blind coal' or _anthracite_. these remarks on the mode of occurrence of igneous rocks are meant to refer chiefly to those masses which occur in regions where volcanic action has long been extinct, as, for instance, in the british islands. in the sequel, some account will be given of the appearances presented by modern volcanoes and volcanic rocks. [ ] it has been usual to apply the term _trap_ or _trappean_ rock to all the old igneous rocks which could neither be classed with the granites and syenites, nor yet with the recent lavas, &c., which are connected with a more or less well-marked volcanic vent. the term _trap_ (swedish _trappa_, a flight of steps) was suggested by the terraced or step-like appearance presented by hills which are built up of successive beds of igneous rock. but the passage from the granitic into the so-called trap rocks, and from these into the distinctly volcanic, is so very gradual, that it is impossible to say where the one class ends and the other begins. the term _trap_, therefore, has no scientific precision, although it is sometimes very convenient as a kind of broad generic term to include a large number of rocks. mineral veins. . the cracks and crevices and joint planes which intersect all rocks in a greater or less degree, are not unfrequently filled with subsequently introduced mineral matter, forming what are termed _veins_. this introduced matter may either be harder or less durable than the rock itself; in the former case, the veins will project from the surface of the stone, where that has been subjected to the weathering action of the atmosphere; in the latter case, the veins, under like circumstances, are often partially emptied of their mineral matter. not unfrequently, however, the more or less irregularly ramifying, non-metalliferous veins appear as if they had segregated from the body of the rock in which they occur, as in the case of the quartz veins in granite. besides these irregular veins, the rocks of certain districts are traversed in one or more determinate directions by fissures, extending from the surface down to unknown depths. these great fissures are often in like manner filled with mineral matter. the minerals are usually arranged in bands or layers which run parallel to the walls of the vein. quartz, fluor-spar, barytes, calcite, &c. are among the commonest vein-minerals, and with these are frequently associated ores of various metals. a vein may vary in width from less than an inch up to many yards, and the arrangement of its contents is also subject to much variation. instead of parallel layers of spars and ores, frequently a confused mass of clay and broken rocks, which are often cemented together with sparry matter, chokes up the vein. the ore in a vein may occur in one or more ribs, which often vary in thickness from a mere line up to masses several yards in width. sometimes the rocks are dislocated along the line of fissure occupied by a great vein; at other times no dislocation can be observed. mineral veins, however, do not necessarily occupy dislocation fissures. they often occur in cavities which have been formed by the erosive action of acidulated water, in the way described in pars. , , and . this is frequently the case in calcareous strata. such veins usually coincide more or less with the bedding of the rocks, but in the case of thick limestones they not unfrequently cut across the bedding in a vertical or nearly vertical direction, forming what are termed _pipe-veins_. dynamical geology. . having considered the composition, structure, and arrangement of the rock-masses which form the solid crust of our globe, we have next to inquire into the nature of those physical agencies by the action of which the rocks, as we now see them, have been produced. the work performed by the various forces employed in modifying the earth's crust is at one and the same time destructive and reconstructive. rocks are being continually demolished, and out of their ruins new rocks are being built. in other words, matter is constantly entering into new relations--now existing as solid rock, or in solution in water, or carried as the lightest dust on the wings of the wind; now being swept down by rivers into the sea, or brought under the influence of subterranean heat--but always changing, sooner or later, slowly or rapidly, from one form to another. the great geological agents of change are these: . the atmosphere; . water; . plants and animals; . subterranean forces. we shall consider these in succession. the atmosphere. . all rocks have a tendency to waste away under the influence of the atmosphere. this is termed _weathering_. under the influence of the sun's heat, the external portions of a rock expand, and again contract when they cool at night. the effect of this alternate expansion and contraction is often strikingly manifest in tropical countries: some rocks being gradually disintegrated, and crumbling into grit and sand; others becoming cracked, and either exfoliating or breaking up all over their surface into small angular fragments. again, in countries subject to alternations of extreme heat and cold, similar weathering action takes place. the chemical action of the atmosphere is most observable in the case of calcareous rocks. the carbonic acid almost invariably present acts as a solvent, so that dew and rain, which otherwise would in many cases have but feeble disintegrating power, are enabled to eat into such rocks as chalk and limestone, calcareous sandstones, &c. the oxygen of the atmosphere also unites with certain minerals, such as the proto-salts of iron, and converts them into peroxides. it is this action which produces the red and yellow ferruginous discolorations in sandstone. chemical changes also take place in the case of many igneous rocks, the result being that a weathered 'crust' forms wherever such rocks are exposed to the action of the atmosphere. of course, the rate at which a rock weathers depends upon its mineralogical and chemical composition. limestones weather much more rapidly than clay-rocks; and augitic igneous rocks, as a rule, disintegrate more readily than the more highly silicated species. the weathering action of the atmosphere is also greatly aided by frost, as we shall see presently. the result of all this weathering is the formation of _soil_--soil being only the fine-grained débris of the weathered rocks. the angular débris found at the base of all cliffs in temperate and arctic regions, and on every hill and mountain which is subjected to alternations of extreme heat and cold, is also the effect of weathering. but these and other effects of frost will be treated of under the head of _frozen water_. the hillocks and ridges of loose sand (_sand dunes_) found in many places along the sea-margin, and even in the interior of some continents, as in africa and asia, are due to the action of the wind, which drives the loose grains before it, and piles them up. sometimes also the wind carries in suspension the finest dust, which may be transported for vast distances before it falls to the ground. thus, fine dust shot into the air by the volcanoes of iceland has been blown as far as the shetland islands; and in tropical countries the dust of the dried-up and parched beds of lakes and rivers is often swept away during hurricanes, and carried in thick clouds for leagues. rain falling through this dust soaks it up, and comes down highly discoloured, brown and red. this is the so-called _blood-rain_. minute microscopic animal and vegetable organisms are often commingled with this dust, and falling into streams, lakes, or the sea, may thus become eventually buried in sediments very far removed from the place that gave them birth. water. . the geological action of water in modifying the crust of the earth is twofold--namely, _chemical_ and _mechanical_. _underground water._--all the moisture which we see falling as rain or snow does not flow immediately away by brooks and rivers to the sea. some portion of it soaks into the ground, and finds a passage for itself by cracks and fissures in the rocks below, from which it emerges at last as springs, either at the surface of the earth, or at the bottom of the sea. such are the more obvious courses pursued by the water--it flows off either by sub-aërial or subterranean channels. but a not inconsiderable portion soaks into the solid rocks themselves, which are all more or less porous and pervious. water thus slowly soaking often effects very considerable chemical changes. sometimes the binding matter which held the separate particles of the rock together is dissolved out, and the rock is thus rendered soft and crumbling; at other times, the reverse takes place, and the water deposits, in the minute interstitial pores, some binding matter by which the partially or wholly incoherent grains are agglutinated into a solid mass. thus what were originally hard and tough rocks become disintegrated to such a degree, that they crumble to powder soon after they are exposed to the air; while some again are converted into a clay, and may be dug readily with a spade. and, on the other hand, loose sand is glued into a hard building-stone. there are many other changes effected upon rocks by water, in virtue of the chemical agents which it holds in solution. indeed, it may be said that there are very few, if any, rocks in which the chemical action of interstitial water has not formerly been, or is not at present being, carried on. besides that which soaks through the rocks themselves, there is always a large proportion of underground water, which, as we have said above, finds a circuitous route for itself by joints, cracks, and crevices. after coursing for, it may be, miles underground, such water eventually emerges as springs, which contain in solution the various ingredients which the water has chemically extracted from the rocks. these ingredients are then deposited in proportion as the mineral water suffers from evaporation. water impregnated with carbonate of lime, for example, deposits that compound as soon as evaporation has carried off a certain percentage of the water itself, and the carbonic acid gas which it held. this is the origin of the mineral called _travertine_ or _calcareous tufa_, which is so commonly met with on the margins of springs, rivers, and waterfalls. . _stalactites_ and _stalagmites_ have been formed in a similar way. water slowly oozing from the roof of a limestone cavern partially evaporates there, and a thin pellicle of carbonate of lime is formed; while that portion of the water which falls to the ground, and is there evaporated, likewise gives rise to the formation of carbonate of lime. by such constant dropping and evaporating, long tongue-and icicle-like pendants (_stalactites_) grow downwards from the roof; while at the same time domes and bosses (_stalagmites_) grow upwards from the floor, so as sometimes to meet the former and give rise to continuous pillars and columns. the great solvent power of carbonated water is shewn first by the chemical analysis of springs, and, secondly, by the great wasting effects which the long-continued action of these has brought about. thus, it has been estimated that the fifty springs near carlsbad, which yield eight hundred thousand cubic feet of water in twenty-four hours, contain in solution as much lime as would go to form a mass of stone weighing two hundred thousand pounds. warm, or, as they are termed, _thermal_ springs, frequently carry away with them, out of the bowels of the earth, vast quantities of mineral matter in solution. the waters at bath, for instance, are estimated to bring to the surface an annual amount of various salts, the mass of which is not less than cubic yards. one of the springs of louèche, france, however, carries out with it no less than , , pounds of gypsum annually, which is equal to about cubic yards. . it is easy to conceive, therefore, that in the course of ages great alterations must be caused by springs. caves and winding galleries, and irregular channels, will be worn out of the rocks which are thus being dissolved. especially will this be the case in countries where calcareous rocks abound. it is in such regions, accordingly, where we meet with the most striking examples of caves and underground river-channels. the largest cave at present known is the mammoth cave, in kentucky. this remarkable hollow consists of numerous winding galleries and passages that cross and recross, and the united length of which is said to be miles. in calcareous countries, rivers, after flowing for, it may be, miles at the surface, suddenly disappear into the ground, and flow often for long distances before they reappear in the light of day. in some regions, indeed, nearly all the drainage is subterranean. the surface of the ground, in calcareous countries, frequently shews circular depressions, caused by the falling in of the roofs of caverns. sometimes, also, great masses of rock, often miles in extent, get loosened by the dissolving action of subterranean water, and crash downwards into the valleys. such _landslips_, as they are called, are not, however, confined to calcareous regions. in , a large section of the rossberg, a mountain lying to the north of the righi, consisting of conglomerate overlying beds of clay, rushed down into the plains of goldau, overwhelming four villages and nearly a thousand inhabitants. the cause of this catastrophe was undoubtedly the softening into mud of the clay-beds on which the conglomerate rested, for the season which had just terminated when the slip took place had been very wet. the mass of material that slid down was estimated to contain upwards of fifty-four millions of cubic yards; it reached not less than two and a half miles in length, by some three hundred and fifty yards wide, and thirty-five yards thick. . _surface-water--rain._--having now learned something as to the modifications produced by underground water, we turn next to consider the action of surface-water, and the results arising from that action. rain, when it falls to the ground, carries with it some carbonic acid gas which it has absorbed from the atmosphere. armed with this solvent, it attacks certain rocks, more especially limestones and chalk, a certain proportion of which it licks up and delivers over to brooks and streams. under its influence, also, the finer particles of the soil are ever slowly making their way from higher to lower levels. rocks which are being gradually disintegrated by weathering have their finer grains and particles, thus loosened, carried away by rain. nor is this rain-action so inconsiderable as might be supposed. in the gentler hollows of an undulating country, we frequently find accumulations of clay, loam, and brick-earth, which often reach many feet in thickness, and which are undoubtedly the results of rain washing down the particles of soil, &c. from the adjacent slopes. . _river-action._--the water of streams and rivers almost invariably contains in solution one or more chemical compounds, and in this respect does not differ from the water of springs. of course, this mineral matter is derived in considerable measure from springs, but is also no doubt to a large extent taken up by the rivers themselves, as they wash the rocks and soils on their journey to the sea. the amount of mineral matter thus transported must be something enormous, as is shewn by the chemical analyses of river-water. bischof calculated that the rhine carries in solution as much carbonate of lime as would suffice for the yearly formation of three hundred and thirty-two thousand millions of oyster-shells of the usual size--a quantity equal to a cube five hundred and sixty feet in the side, or a square bed a foot thick, and upwards of two miles in the side. but the mechanical erosion effected by running water is what impresses us most with the importance of rivers as geological agencies. this erosive action is due to the gravel, sand, and mud carried along by the water. these ingredients act as files in the hand of a workman, and grind, polish, and reduce the rocks against which they are borne. the beds of some streams that flow over solid rock are often pitted with circular holes, at the bottom of which one invariably finds a few rounded stones. these stones, kept in constant motion by the water, are the means by which the _pot-holes_, as they are called, have been excavated. when pot-holes are numerous, they often unite so as to form curious smooth-sided trenches and gullies. the same filing action goes on all over the bed of the stream wherever the solid rock is exposed. and while the latter is being gradually reduced, the stones and grit which act as the files are themselves worn and reduced; so that stones diminish in size, and grit passes into fine sand and mud, as they move from higher to lower levels. no doubt the erosive action of running water appears to have but small effect in a short time, and we are apt, therefore, to underestimate its power. but when our observations extend, we see it is quite otherwise, and that, so far from being unimportant, running water is really one of the most powerful of all the geological agencies that are employed in modifying the earth's crust. even within a comparatively short time, it is able to effect very considerable changes. thus, the river simeto, in sicily, having become dammed by a stream of lava flowing from etna, succeeded, in two hundred and fifty years, in cutting through hard solid basalt a new channel for itself, which measured from twenty to fifty mètres in depth, and from twelve to eighteen in breadth. when, also, we remember the fact, that no river is absolutely free from mineral matter held in suspension, but that, on the contrary, all running water is more or less discoloured with sediment, which is merely the material derived from the disintegration of rocks, it will appear to us difficult to overestimate the power of watery erosion. to the mineral matter held in suspension, we have to add the coarser detritus, gravel and sand, which is being gradually pushed along the beds of rivers, and which, in the case of the mississippi, has been estimated to equal a mass of seven hundred and fifty million cubic feet, discharged annually into the gulf of mexico. by careful measurements, it has also been ascertained that the same river carries down annually into the sea a weight of mud held in suspension which reaches the vast sum of , , , pounds. the total annual amount of mineral matter, whether held in suspension or pushed along the bottom of this great river, has been estimated to equal a mass feet in height, with an area of one square mile. . _alluvium._--the sediment carried along and deposited by a river is called _alluvium_. sometimes this alluvium covers wide areas, forming broad flats on one or both sides of a river, and in such cases it is due to the action of the floodwaters of the stream. every time the river overflows the low grounds through which it passes, a layer of sediment is laid down, which has the effect of gradually raising the level of the alluvial tract. by and by a time comes when the river, which has all the while been slowly deepening its channel, is unable to flood the flats, and thereupon it begins to cut into these, and to form new flats at a somewhat lower level. in this way we often observe a series of alluvial terraces, consisting of gravel, sand, and silt, rising one above another along a river valley. such are the terraces of the thames and other rivers in england, and of the tweed, clyde, tay, &c. in scotland. the great plains through which the rhine flows between basel and bingen, are also well-marked examples of alluvial accumulations. there are very few streams, indeed, which have not formed such deposits along some portion of their course. . when a river enters a lake, the motion of the water is of course checked, and hence the heavier detritus, such as gravel and coarse sand, moves more slowly forward, and at last comes to rest on the bed of the lake, at no great distance from the mouth of the river. finer sand and mud are carried out for some distance further, but eventually they also cease to move, and sink to the bottom. when the lake is sufficiently large, it catches all or nearly all the matter brought down by the river, which, as it issues from the lower end of the lake, is bright and clear. a well-known example of this phenomenon is that of the rhone, which enters the lake of geneva turbid and muddy, but rushes out quite clear at the lower end of the lake. lakes, therefore, are all being slowly or more rapidly silted up, and this, of course, is most conspicuous at the points where they are entered by rivers. thus, at the head of the lake of geneva, it is manifest that the wide flat through which the river flows before it pours into the lake, has been conquered by the rhone from the latter. in the times of the romans, the lake, as we know, extended for more than one mile and a half further up the valley. . _deltas._--when there are no lakes to intercept fluviatile sediment, this latter is borne down to the sea, where it is deposited in precisely the same way as in a lake: the heavier detritus comes to rest first, the finer sediment being swept out for some distance further. so that, in passing from the river-mouth outwards, we have at first gravel, which gradually gets finer and finer until it is replaced by sand, while this in turn is succeeded by mud and silt. there is this difference, however, between lacustrine and fluvio-marine deposits, that while the former accumulate in water which is comparatively still, the latter are often brought under the influence of waves and currents, and become shifted and sifted to such a degree that fine and coarse detritus are frequently commingled; and there is, therefore, not the same orderly succession of coarse and fine materials which characterises lacustrine deposits. often, indeed, the currents opposite the mouth of a river are so strong, that little or no sediment is permitted to gather there. usually, however, we find that rivers have succeeded in reclaiming more or less wide tracts from the dominion of the waves, or at all events have cumbered the bed of the sea with banks and bars of detritus. the broad plains formed at the mouth of a river are called _deltas_, from their resemblance to the greek letter [delta]. the deltas of the nile, ganges, and mississippi are among the most noted. the term _delta_, however, is not exclusively applied to fluvio-marine deposits; rivers also form deltas in fresh-water lakes. it is usual, however, to restrict the term to extensive alluvial plains which are intersected by many winding channels, due to the rapid bifurcation of the river, which begins to take place at the very head of the great flat--that is to say, at the point where the river originally entered the sea (or lake). . _frozen water._--we have now seen what can be done by the mechanical action of running water. we have next to consider what modifications are effected by freezing and frozen water. water, as every one knows, expands in the act of freezing, and in doing so exerts great force. let the reader bear in mind what has been said as to the passage of water through the minute and often invisible pores of rocks, and to its presence in cracks and crevices after every shower of rain, and he will readily see how excessive must be the waste caused by the action of frost. the water, to as great a depth as the frost extends, passes into the solid state, and in doing so pushes the grains of the rocks asunder, or wedges out large masses. no sooner does thaw ensue than the water, becoming melted, allows the grains of the rock to fall asunder; the outer skin of the rock, as it were, is disintegrated, and crumbles away, while fragments and masses lose their balance in many cases, and topple down. hence it is, that in all regions where frost acts, the hill-tops and slopes are covered with angular fragments and débris, and a soil is readily formed by the disintegration of the rocks. river-ice is often a potent agent of geological change. stones get frozen in along the margins of a river, and often débris falls down from cliff and scaur upon the surface of the ice; when thaw sets in, and the ice breaks up, stones and rubbish are frequently floated for long distances, and may even be carried out to sea before their support fails them, and they sink to the bottom. in some cases, when the ice is very thick, it may run aground in a river, and confuse and tumble up the deposits gathering at the bottom. ice sometimes forms upon stones at the bottom of a river, and floats these off; and this curious action may take place even although no ice be forming at the time on the surface of the water. . _glaciers, icebergs, and ice-foot._--in certain mountainous districts, and in arctic and antarctic regions, snow accumulates to such an extent that its own weight suffices to press the lower portions into ice. alternate thawing and freezing also aid in the formation of the ice, which soon begins to creep down the mountain-slopes into the valleys, where it constitutes what are called _glaciers_ or ice-rivers. these great masses of ice attain often a great thickness, and frequently extend for many miles along the course of a valley. in the alps they occasionally reach as much as five hundred or six hundred feet in depth. in greenland, however, there are glaciers probably not less than five thousand feet thick; and the glacier ice of the antarctic continent has been estimated even to reach twelve miles in thickness. glaciers flow slowly down their valleys, at a rate which varies with the slope of their beds and the mass of the ice. some move only a few inches, others two or three feet, in a day. their forward motion is arrested at a point where the ice is melted just as fast as it comes on. a glacier is always more or less seamed with yawning cracks, which are called _crevasses_. these owe their origin to the unequal rate at which the different parts of the ice flow; this differential motion causing strains, to which the ice yields by snapping asunder. the flanks of a glacier are usually fringed with heaps of angular blocks and débris which fall from the adjacent rocky slopes, and some of this rubbish tumbling into the gaping crevasses must occasionally reach to the bottom of the ice. the rubbish heaps (_superficial moraines_) travel slowly down the valley on the surface of the ice, and are eventually toppled over the end of the glacier, where they form great banks and mounds. these are called _terminal moraines_. the rocky bed of a glacier is invariably smoothed and polished, and streaked with coarse and fine _striæ_, or scratches, which run parallel to the direction of the ice-flow. these are due to the presence, at the bottom of the ice, of such angular fragments as become detached from the underlying rocks, or of boulders and rubbish which have been introduced from above. the stones are ground by the ice along the surface of its bed, causing ruts and scratches, while the finer material resulting from the grinding action forms a kind of polisher. the stones acting as gravers are themselves covered with striæ, and their sharp edges get smoothed away. in alpine districts there is always a good deal of water circulating underneath a glacier, and this washes out the sand and fine clay. thus it is that rivers issuing from glaciers are always more or less discoloured brown, yellow, green, gray, or blue, according to the nature of the rocks which the ice has pounded down into mud. in greenland many of the large glaciers go right out to sea, and owing to their great thickness are able to dispossess the sea sometimes for miles. but erelong the greater specific gravity of the sea-water forces off large segments from the terminal front of the ice, which float away as _icebergs_. large masses are also always falling down from the ice-front. occasionally, big blocks and débris are floated away on the icebergs, but this does not appear to be common. in greenland there is very little rock-surface exposed, from which blocks can be showered down upon the glaciers, and the surface of the latter is therefore generally free from superficial moraines. a kind of submarine terminal moraine, however, gathers in front of some glaciers, made up chiefly of the stones and rubbish that are dragged along underneath the ice, and exposed by the breaking-off of icebergs, but partly composed also of the sand and mud washed out by sub-glacial waters. a narrow belt of ice forms along the sea-coast in arctic regions, which often attains a thickness of thirty or forty feet. this is called the _ice-foot_. it becomes loaded with débris and blocks, which fall upon it from the cliffs above; and, as large portions are frequently detached from the cliffs in summer-time, they sail off with their cargoes of débris, and drop these over the sea-bottom as they gradually melt away. the ice-foot is the great distributor of _erratics_ or wandered blocks, the part taken in this action by the huge icebergs which are discharged by the glaciers being, comparatively speaking, insignificant. but when these latter run aground, they must often cause great confusion among the beds of fine material accumulating upon the floor of the sea. . _the sea._--sea-water owes its saltness to the presence of various more or less soluble substances, such as _common salt_, _gypsum_, _epsom salts_, _chloride of magnesium_, &c. besides these, there are other ingredients held in solution, which, although they can be detected in only minute quantities in sea-water, are yet of the very utmost importance to marine creatures. this is the case with _carbonate of lime_, vast quantities of which are carried down by many rivers to the sea. but it must be nearly all used up in the formation of hard shells and skeletons by molluscs, crustaceans, corals, &c., for very little can be traced in the water itself. _silica_ is also met with sparingly, and is abstracted by some creatures to form their hard coverings. . _breaker-action--currents._--the most conspicuous action of the sea, as a geological agent, takes place along its margin, where the breakers are hurled against the land. stones and gravel are borne with more or less intense force against the rocks, and by their constant battering succeed eventually in undermining the cliffs, which by and by become top-heavy, and large masses fall down and get broken up and pounded into gravel and sand. the new wall of rock thus exposed becomes in turn assaulted, and in course of time is undermined in like manner. the waste of the cliffs is greatly aided by the action of frost, which loosens the jointed rocks, and renders them an easier prey to the force of the waves. of course, the rapidity with which a coast-line is eaten into depends very much upon the nature of the rocks. where these are formed of loose materials like sand, gravel, or clay, considerable inroads are effected by the sea in a comparatively short time. thus, along some parts of the english coast, as between flamborough head and the mouth of the humber, and between the wash and the thames, it is estimated that the land is wasted away at the rate of a yard per annum. where hard rocks form the coast-line the rate of waste is often exceedingly slow, and centuries may elapse without any apparent change being effected. when the rocks are of unequal hardness the coast-line becomes very irregular, the sea carving out bays and gullies in the softer portions, while the more durable masses stand out as capes and bold headlands. not unfrequently, such headlands are converted into sea-stacks and rocky islets, as one may observe along the rockier parts of our shore-lines. close inshore, the bulkier débris derived from the waste of the land often accumulates, forming beds and banks of shingle and gravel. the finer materials are carried farther out to sea, and distributed over the sea-floor by the action of the tide and currents. tidal and other currents may also have some denuding effect upon the sea-bottom, but this can only be in comparatively shallow water. the great bulk of the material derived from the waste of the coasts by the mechanical action of the breakers, travels for no great distance. but the fine mud brought down by rivers is frequently transported for vast distances before it settles. so fine, indeed, is some of this sedimentary material, that it may be carried in suspension by sea-currents for thousands of miles before it sinks to the bottom. . from this short outline it becomes evident, therefore, that the coarser-grained the deposit, the smaller will be the area it covers; while conversely, the finer the accumulation, the more widely will it be distributed. a partial exception to this rule is that of the débris scattered over the bottom of the ocean by icebergs and detached portions of ice-foot. these are often floated for vast distances by currents before they finally melt away, and hence the coarse débris transported by them must be very widely distributed over that part of the sea-bottom which is traversed by currents flowing out of the arctic and antarctic oceans. although the deeper recesses of the ocean appear to be covered only with ooze and fine mud, yet in some instances coarse sand, and even small stones, have been brought up from depths of a hundred fathoms, so that currents may occasionally carry coarser materials for great distances from the shore. the shifting action of tidal currents succeeds in giving rise to very irregular deposits in shallow seas. the soundings often shew sudden changes from gravel to sand and mud, nor can there be any doubt that, could we lay bare the sea-bottom, we should often observe gravel shading off into sand, and sand into mud, and _vice versâ_. but as we receded from the shore, and approached areas which were once deeply submerged, we should find that the change of material was generally from coarse to fine. geological action of plants and animals. . _plants._--the disintegration of rocks is often aided by the action of plants, which force their roots into joints and crevices, and thus loosen blocks and fragments. carbonic acid, derived from the decay of plants, being absorbed by rain-water, acts chemically upon many rocks, as in the case of limestone (see , , ). in temperate regions, vegetation frequently accumulates, under certain conditions, to form very considerable masses. of such a nature is _peat_, which, as is well known, covers many thousands of acres in the british islands. this substance is composed fundamentally of the bog-moss (_sphagnum palustre_), with which, however, are usually associated many other marsh-loving plants. the lower parts of bog-moss die and decay while its upper portions continue to flourish, and thus, in process of time, a thickness of peat is accumulated to the extent of six, twelve, twenty-four, or even forty feet. many of the hill-tops and hill-slopes in scotland and ireland are covered with a few feet of peat, but it is only in valleys and hollows where the peat-bogs attain their greatest depth. in not a few cases, the bogs seem to occupy the sites of ancient lakes, shell-marl often occurring at the bottom of these. the trunks and roots of trees are also commonly met with underneath peat, and occasionally the remains of land animals. frequently, indeed, it would seem as if the overthrow of the trees, by obstructing the drainage of the country, had given rise to a marsh, and the consequent formation of peat. some of the most valuable peat closely resembles lignite, and makes a good fuel. in tropical countries, the rapidity with which vegetation decays prevents, as a rule, any great accumulation taking place; but the mangrove swamps are exceptions. . _animals._--the action of animal life is for the most part conservative and reconstructive. considerable accumulations of shell-marl take place in fresh-water lakes, and the flat bottoms which mark the sites of lakes which have been drained are frequently dug to obtain this material. but by far the most conspicuous formations due to the action of animal life accumulate in the sea. molluscs, crustaceans, corals, and the like, secrete from the ocean the carbonate of lime of which their hard shells and skeletons are composed, and these hard parts go to the formation of limestone. the most remarkable masses of modern limestone occur within intertropical regions. these are the coral reefs of the pacific and indian oceans. [illustration: fig. .--formation of coral reefs.] . _coral_ is the calcareous skeleton of certain small soft-bodied gelatinous animals called _actinozoa_. these zoophytes flourish only in clear water, the temperature of which is not below ° f., and they cannot live at greater depths than one hundred feet. there are three kinds of coral reef--namely, _fringing_ reefs, _barrier_ reefs, and _atolls_. fringing reefs occur, as a rule, near to the shore; but if this latter be gently sloping, they may extend for one or even two miles out to sea; as far, indeed, as the depth of water is not too great for the actinozoa. barrier reefs are met with at greater distances from the land, and often rise from profound depths. the barrier reef which extends along the north-east coast of australia, often at a distance from the land of fifty or sixty miles, stretches, with interruptions, for about miles, with a breadth varying from ten to ninety miles. in some places, the depth of the sea immediately outside of this reef exceeds feet. sometimes barrier reefs completely encircle an island or islands, which are usually mountainous, as in the case of pouynipète, an island in the caroline archipelago, and the gambier islands in the low archipelago. _atolls_ are more or less irregular ring-shaped reefs inclosing a lagoon of quiet water. they usually rise from profound depths; keeling atoll, in the indian ocean, is a good example. the upper surface of atolls and barrier reefs often peers at separate points above the level of the sea, so as to form low-lying islets. in some cases, the land thus formed is almost co-extensive with the reef, and being clothed with palms and tropical verdure, resembles a beautiful chaplet floating, as it were, in mid-ocean. the rock of a coral reef is a solid white limestone, similar in composition to that of the limestones occurring in this country. in some places, it is quite compact, shewing few or no inclosed shells or other animal remains; in other places, it is made up of broken and comminuted corals cemented together, or of masses of coral standing as they slowly grew, with the spaces between the separate clumps filled up with coral sand and triturated fragments and grit of coral and shell. the thickness of the reefs is often very great, reaching in many cases to thousands of feet. at the fijis, the reef can hardly be less than or feet thick. below a depth of one hundred feet, all the coral rock is dead, and since the coral zoophytes do not live at greater depths than this, it follows that the bed of the sea in which coral reefs occur must have slowly subsided during a long course of ages. mr darwin was the first to give a reasonable explanation of the origin of coral reefs. briefly stated, his explanation is as follows: the corals began to grow first in water not exceeding one hundred feet in depth, and built up to the surface of the sea, thus forming a fringing reef at no great distance from the land. this initial step is shewn at a, b, in the accompanying section across a coral island. a, a, are the outer edges of the fringing reef; b, b, the shores of the island; and s the level of the sea. subsidence ensuing, the island and the sea-bottom sink slowly down, while the coral animals continue to grow to the surface--the building of the reef keeping pace with the subsidence. by and by the island sinks to the level s , when b´, b´, represent the shores of the now diminished island, and a´, a´, the outer edges of the reef, which has become a barrier reef; c, c, being the lagoon between the reef and the central island. we have now only to suppose a continuance of the submergence to the level s , when the island disappears, its site being occupied by a lagoon, c´--the reef, which has at the same time become an atoll, being shewn at a´´, a´´. . in extra-tropical latitudes, great accumulations of carbonate of lime are also taking place. the bottom of the atlantic has been found to be covered, over vast areas, by a fine calcareous sticky deposit called _ooze_, which would appear to consist for the most part of the skeletons of minute animal organisms, called foraminifera. this accumulation, when dried, closely resembled chalk, and there can be no doubt that in the deep recesses of the atlantic we have thus a gradually increasing deposit of carbonate of lime, which rivals, if it does not exceed, in extent the most widely spread calcareous rocks with which we are acquainted. a small percentage of siliceous materials occurs in the ooze, made up partly of granules of quartz, and partly of the skeletons and coverings of minute animal and vegetable organisms. when in process of time the chemical forces begin to act upon the siliceous matter diffused through the atlantic ooze, _segregation_, or the gathering together of the particles, may take place, and nodules of flint will be the result, similar to the flint nodules which occur in chalk, and the cherty concretions in limestones. animalcules with siliceous envelopes and skeletons are by no means so abundant as those that secrete carbonate of lime, but they are very widely diffused through the oceans, and in favourable places are so abundant that they may well give rise eventually to extensive beds of flint. ehrenberg calculated that , cubic feet of these organisms were formed annually in the muddy bottom of the harbour at wismar, in the baltic. it would appear from recent observations (_challenger_ expedition) that the calcareous ooze at the bottom of the atlantic and southern oceans, which occurs at a mean depth of fathoms, passes gradually as the ocean deepens into a gray ooze, which is less calcareous, and which occurs at a mean depth of fathoms. at still greater depths this gray ooze also disappears, and is replaced by red clay at a mean depth of fathoms. the minute creatures (foraminifera and pelagic mollusca chiefly) whose shells go to form the calcareous ooze, live for the most part on the surface, and swarm all over the areas in which ooze and red clay occur at the bottom. hence it seems probable that the clay is merely the insoluble residue or _ash_, as it were, of the organisms--the delicate shells, as they slowly sink to the more profound depths, being dissolved by the free carbonic acid, which, as observations would seem to shew, occurs rather in excess at great depths. thus we see how the organic forces may give rise to extensive accumulations of inorganic matter, closely resembling the finest silt or mud which is carried down to the sea by rivers, and distributed far and wide by ocean currents. subterranean forces. . there have been many speculations as to the condition of the interior of the earth. some have inferred that the external crust of the globe incloses a fluid or molten mass; others think it more probable that the interior is solid, but contains scattered throughout its bulk, especially towards the surface of the earth, irregular seas of molten matter, occupying large vesicles or tunnels in the solid honey-combed mass. at present, the facts known would appear to be best explained by the latter hypothesis. all that we know from observation is, that the temperature increases as we descend from the surface. the rate of increase is very variable. thus, in the artesian well at neuffen, in würtemberg, it was as much as ° f. for every feet. in the mines of central germany, however, the increase is only ° f. for every feet; while in the dukinfield coal-pit, near manchester, the increase was still less, being only ° f. in feet. taking the average of many observations, it may be held as pretty well proved that the temperature of the earth's crust increases ° for every or feet of descent after the first hundred. . the crust of the earth is subject to certain movements, which are either sudden and paroxysmal, or protracted and tranquil. the former are known as earthquakes, which may or may not result in a permanent alteration of the relative level of land and sea; the latter always effect some permanent change, either of upheaval or depression. . _earthquakes_ have been variously accounted for. those who uphold the hypothesis of a fluid interior think the undulatory motion experienced at the surface is caused by movements in the underlying molten mass--an earthquake being thus 'the reaction of the liquid nucleus against the outer crust.' by others, again, earthquakes are supposed to be caused by the fall of large rock-masses from the roofs of subterranean cavities, or by any sudden impulse or blow, such as might be produced by the cracking of rocks in a state of tension, by a sudden volcanic outburst, or sudden generation or condensation of steam. in support of this latter hypothesis, many facts may be adduced. the undulatory motion communicated to the ground during gunpowder explosions, or by the fall of rocks from a mountain, is often propagated to great distances from the scene of these catastrophes, and the phenomena closely resemble those which accompany a true earthquake. when the level of a district has been permanently affected by an earthquake, the movement has generally resulted in a lowering of the surface. thus, in , the great runn of cutch, in hindustan, was depressed over an area of several thousand square miles, so as during the monsoons to become a salt lagoon. occasionally, however, we find that elevation of the land has taken place during an earthquake. this was the case in new zealand in , when the ground on which the town of wellington stands rose about two feet, and a cape in the neighbourhood nearly ten feet. sometimes the ground so elevated is, after a shorter or longer period, again depressed to its former level. a good example of this occurred in south america in . the shore at concepcion was raised a yard and a half; and the isle santa maria was pushed up two and a half yards at one end, and three and a half yards at the other. but only a few months afterwards the ground sank again, and everything returned to its old position. the heaving and undulatory motion of an earthquake produces frequently considerable changes at the surface of the ground, besides an alteration of level. rocks are loosened, and sometimes hurled down from cliff and mountain-side, and streams are occasionally dammed with the soil and rubbish pitched into them. sometimes also the ground opens, and swallows whatever chances to come in the way. if these chasms close again permanently, no change in the physiography of the land may take place, but sometimes they remain open, and affect the drainage of the country. . _movements of upheaval and depression._--besides the permanent alteration of level which is sometimes the result of a great earthquake, it is now well known that the crust of the earth is subject to long-continued and tranquil movements of elevation and depression. the cause of these movements is at present merely matter for speculation, some being of opinion that they may be caused by the gradual contraction of the slowly cooling nucleus of the earth, which would necessarily give rise to depression, while this movement, again, would be accompanied by some degree of elevation--the result of the lateral push or thrust effected by the descending rock-masses. it is doubtful, however, if this hypothesis will explain all the appearances. the scandinavian peninsula affords a fine example of the movements in question. at the extremity of the peninsula (scania), the land is slowly sinking, while to the north of that district gradual elevation is taking place at a very variable rate, which in some places reaches as much as two or three feet in a century. movements of elevation are also affecting spitzbergen, northern siberia, north greenland, the whole western borders of south america, japan, the kurile islands, asia minor, and many other districts in the mediterranean area, besides various islets in the great pacific ocean. the proofs of a slow movement of elevation are found in old _sea-beaches_ and _sea-caves_, which now stand above the level of the sea. in the case of scandinavia, it has been noticed that the pine-woods which clothe the mountains are being slowly elevated to ungenial heights, and are therefore gradually dying out along their upper limits. the proofs of depression of the land are seen in submerged forests and peat, which occur frequently around our own shores, and there is also strong human testimony to such downward movements of the surface. the case of scania has already been referred to. several streets in some of its coast towns have sunk below the sea, and it is calculated that the scanian coast has lost to the extent of thirty-two yards in breadth within the past hundred and thirty years. the coral reefs of southern oceans also afford striking evidence of a great movement of depression. not long ago a theory was started by a french savant, m. adhémar, to account for changes in the sea-level, without having recourse to subterranean agency. he pointed out that a vast ice-cap, covering the northern regions of our hemisphere, as was certainly the case during what is termed the glacial epoch, would cause a rise of the sea by displacing the earth's centre of gravity. mr james croll has recently strongly supported this opinion; and there can be no doubt that we have here a _vera causa_ of considerable mutations of level. it is unquestionably true, however, that great oscillatory movements, such as described above, and which can only be attributed to subterranean agencies, have frequently taken and are still taking place. . such movements of the earth's crust cannot take place without effecting some change upon the strata of which that crust is composed. during _depression_ of the curved surface of the earth, the under strata must necessarily be subjected to intense lateral pressure, since they are compelled to occupy less space, and contortion and plication will be the result. it is evident also that contortion will diminish from below upwards, so that we can conceive that excessive contortion may be even now taking place at a great depth from the surface in greenland. during a movement of _elevation_, on the other hand, the strata are subjected to excessive tension, and must be seamed with great rents: when the elevating force is removed, the disrupted rocks will settle down unequally--in other words, they will be _faulted_, and their continuity will be broken. but both contortion and faulting may be due, on a small scale, to local causes, such as the intrusion of igneous rocks, the consolidation of strata, the falling in of old water-courses, &c. _cleavage_ is believed to have been caused by compression, such as the rocks might well be subjected to during great movements of the earth's crust. the particles of which the rock is composed are compressed in one direction, and of course are at the same time drawn out at right angles to the pressure. this is observed not only as regards the particles of the rock themselves, but imbedded fossils also are distorted and flattened in precisely the same way. . _volcanoes._--besides movements of elevation and depression, there are certain other phenomena due to the action of the subterranean forces. such are the ejection from the interior of the earth of heated matters, and their accumulation upon the surface. the erupted materials consist of molten matter (lava), stones and dust, gases and steam--the lava, ashes, and stones gradually accumulating round the focus of ejection, and thus tending to form a conical hill or mountain. could we obtain a complete section of such a volcanic cone, we should find it built up of successive irregular beds of lava, and layers of stones and ashes, dipping outwards and away from the source of eruption, but having round the walls of the _crater_ (that is, the cavity at the summit of the truncated cone) a more or less perceptible dip inwards. fig. gives a condensed view of the general phenomena accompanying an eruption. in this ideal section, _a_ is the funnel or neck of the volcano filled with lava; _b_, _b_, the crater. the molten lava is highly charged with elastic fluids, which continually escape from its surface with violent explosions, and rise in globular clouds, _d_, _d_, to a certain height, after which they dilate into a dark cloud, _c_. from this cloud showers of rain, _e_, are frequently discharged. large and small portions of the incandescent lava are shot upwards as the imprisoned vapour of water explodes and makes its escape, and, along with these, fragments of the rocks forming the walls of the crater and the funnel are also violently discharged; the cooled bombs, angular stones, and _lapilli_, as the smaller stones are called, falling in showers, _f_, upon the exterior parts of the cone or into the crater, from which they are again and again ejected. most frequently the great weight of the lava inside the crater suffices to break down the side of the cone, and the molten rock escapes through the breach. sometimes, however, it issues from beneath the base of the cone. at other times, finding for itself some weak place in the cone, it may flow out by a lateral fissure, _g_. in the diagram, _i_, _i_ represents the lava streaming down the outward slopes, jets of steam and fumaroles escaping from almost every part of its surface. forked lightning often accompanies an eruption, and is supposed to be generated by the intense mutual friction in the air of the ejected stones. the trituration to which these are subjected reduces them, first, to a kind of coarse gravel (_lapillo_); then to sand (_puzzolana_); and lastly, to fine dust or ashes (_ceneri_). [illustration: fig. .--diagrammatic section of volcano.] . _lava._--any rock which has been erupted from a volcano in a molten state is called _lava_. some modern lava-streams cover a great extent of surface. one of two streams which issued from the volcano of skaptur jokul (iceland) in overflowed an area fifty miles in length, with a breadth in places of fifteen; the other was not much less extensive, being forty miles in length, with an occasional breadth of seven. in some places the lava exceeded feet in thickness. again, in , an eruption in the island of hawaii sent forth a stream of lava sixty-five miles long, and from one to ten miles wide. the surface of a stream quickly cools and consolidates, and in doing so shrinks, so as to become seamed with cracks, through which the incandescent matter underneath can be seen. as the current flows on, the upper crust separates into rough ragged scoriform blocks, which are rolled over each other and jammed into confused masses. the slags that cake upon the face or front of the stream roll down before it, and thus a kind of rude pavement is formed, upon which the lava advances and is eventually consolidated. thus, in most cases, a bed of lava is scoriaceous as well below as above. other kinds of lava are much more ductile and viscous, and coagulate superficially in glossy or wrinkled crusts. when lava has inclosed fragments of aqueous rocks, such as limestone, clay, or sandstone, these are observed to have undergone some alteration. the sandstone is often much hardened, the clay is porcelainised, and the limestone, still retaining its carbonic acid, assumes a crystalline texture. but the aqueous rock upon which lava has cooled does not usually exhibit much change, nor does the alteration, as a rule, extend more than a few feet (often only a few inches) into the rock. a lava-current which entered a lake or the sea, however, has sometimes caught up much of the sediment gathering there, and become so commingled with it, that in some parts it is hard to say whether the resulting rock is more igneous or aqueous. lava which has been squirted up from below into cracks and crevices, and there consolidated so as to form _dykes_, sometimes, but not often, produces considerable alteration upon the rocks which it intersects. the basaltic structure is believed to be due to the contraction of lava consequent upon its cooling. the axes of the prisms are always perpendicular to the cooling surface or surfaces, and in some cases the columns are wonderfully regular. there are numerous varieties of lava, such as _basalt_, _obsidian_, _pitchstone_, _pearlstone_, _trachyte_, &c.; some are heavy compact rocks, others are light and porous. many are finely or coarsely crystalline; others have a glassy and resinous or waxy texture. some shew a flaky or laminated structure; others are concretionary. most of the lava rocks, however, are granularly crystalline. in many, a vesicular character is observed. these vesicles, being due to the bubbles of vapour that gathered in the molten rock, usually occur in greatest abundance towards the upper surface of a bed of lava. they are also more or less well developed near the bottom of a bed, which, as already explained, is frequently scoriaceous. occasionally the vesicles are disseminated throughout the entire rock. as a rule, those lavas which are of inferior specific gravity are much more vesicular than the denser and heavier varieties. the vesicles are usually more or less flattened, having been drawn out in the direction in which the lava-current flowed. sometimes they are filled, or partially filled, with mineral matter introduced at the time of eruption, or subsequently brought in a state of solution and deposited there by water filtering through the rock: this forms what is called _amygdaloidal lava_. in volcanic districts, the rocks are often traversed by more or less vertical dykes or veins of igneous matter. these dykes appear in some cases to have been formed by the filling up of crevices from above--the liquid lava having filtered downwards from an overflowing mass. in most cases, however, the lava has been injected from below, and not unfrequently the 'dykes' seem to have been the feeders from which lava-streams have been supplied--the feeders having now become exposed to the light of day either by some violent eruption which has torn the rocks asunder, or else by the gradual wearing away of the latter by atmospheric and aqueous agencies. metamorphism. . mention has already been made of the fact, that the heated matters ejected from volcanoes, or forcibly intruded into cracks, crevices, &c., occasionally _alter_ the rocks with which they come in contact. when this alteration has proceeded so far as to induce a crystalline or semi-crystalline character, the rock so altered is said to be metamorphosed. metamorphism has likewise been produced by the chemical action of percolating water, which frequently dissolves out certain minerals, and replaces these with others having often a very different chemical composition. but metamorphism on the large scale--that is to say, metamorphism which has affected wide areas, such as the northern highlands of scotland and wide regions in scandinavia, or the still vaster areas in north america--has most probably been effected both by the agency of heat and chemical action, at considerable depths, and under great pressure. when we observe what effect can be produced by heat upon rocks, under little or no pressure, and how water percolating from above gradually changes the composition of some rock-masses, we may readily believe that at great depths, where the heat is excessive, such metamorphic action must often be intensified. thus, for example, limestone heated in the usual way gives off its carbonic acid gas, and is reduced to quicklime; but, under sufficient pressure, this gas is not evolved, the limestone becoming converted into a crystalline marble. some crystalline limestones, indeed, have all the appearance of having at one time been actually melted and squirted under great pressure into seams and cracks of the surrounding strata. heated water would appear to have been the agent to which much of the metamorphism which affects the rocky strata must be attributed. but the mode or modes in which it has acted are still somewhat obscure; as may be readily understood when it is remembered how difficult, and often how impossible it is to realise or reproduce in our laboratories the conditions under which deep-seated metamorphic action must frequently have taken place. in foliated rocks, the minerals are chiefly quartz, felspar, and mica, talc, or chlorite. the ingredients of these minerals undoubtedly existed in a diffused state in the original rocks, and heated water charged with alkaline carbonates, as it percolated through the strata, either along the layers of bedding or lines of cleavage, slowly acted upon these, dissolving and redepositing them, and thus inducing segregation. there is every kind of gradation in metamorphism. thus, we find certain rocks which are but slightly altered--their original character being still quite apparent; while, in other cases, the original character is so entirely effaced that we can only conjecture what that may have been. when we have a considerable thickness of metamorphic rocks which still exhibit more or less distinct traces of bedding, like the successive beds of gneiss, mica-schist, and quartz rock of the scottish highlands, we can hardly doubt that the now crystalline masses are merely highly altered aqueous strata. but there are cases where even the bedding becomes obliterated, and it is then much more difficult to determine the origin of the rocks. thus, we find bedded gneiss passes often, by insensible gradations, into true amorphous granite. there has been much difference of opinion as to the origin of granite--some holding it to be an igneous rock, others maintaining its metamorphic origin. it is probably both igneous and metamorphic, however. if we conceive of certain aqueous rocks becoming metamorphosed into gneiss, we may surely conceive of the metamorphism being still further continued until the mass is reduced to a semi-fluid or pasty condition, when all trace of foliation and bedding might readily disappear, and the weight of the superincumbent strata would be sufficient to force portions of the softened mass into cracks and crevices of the still solid rocks above and around it. hence we might expect to find the same mass of granite passing gradually in some places into gneiss, and in other places protruding as _veins_ and _dykes_ into the surrounding rocks; and this is precisely what occurs in nature. . _mineral veins_ have, as a rule, been formed by water depositing along the walls of fissures the various matters which they held in solution, but certain kinds of veins (such as quartz veins in granite) probably owe their origin to chemical action which has induced the quartz to segregate from the rock mass. some have maintained that the metallic substances met with in many veins owe their deposition to the action of currents of voltaic electricity; while others have attributed their presence to sublimation from below, the metals having been deposited in the fissures very much as lead is deposited in the chimney of a leadmill. but in many cases there seems little reason to doubt that the ores have merely been extracted from the rocks, and re-deposited in fissures, by water, in the same way as the other minerals with which they are associated. physiography. . _denudation._--by the combined action of all the geological agencies which have been described in the preceding sections, the earth has acquired its present diversified surface. valleys, lacustrine hollows, table-lands, and mountains have all been more or less slowly formed by the forces which we see even now at work in the world around us. when we reflect upon the fact that all the inclined strata which crop out at the surface of the ground are but the truncated portions of beds that were once continuous, and formed complete anticlinal arches or curves, we must be impressed with the degree of _denudation_, or wearing-away, which the solid strata have experienced. if we protract in imagination the outcrop of a given set of strata, we shall find them curving upwards into the air to a height of, it may be, hundreds or even thousands of feet, before they roll over to come down and fit on to the truncated ends of the beds on the further side of the anticline (see figs. and , pages , ). _dislocations_ or _faults_ afford further striking evidence in the same direction. sometimes these have displaced the strata for hundreds and even thousands of feet--that is to say, that a bed occurring at, for example, a few feet from the surface upon one side of a fault, has sunk hundreds or thousands of feet on the other side. yet it often happens that there is no irregularity at the surface to betray the existence of a dislocation. the ground may be flat as a bowling-green, and yet, owing to some great fault, the rocks underneath one end of the flat may be geologically many hundred feet, or even yards, higher or lower than the strata underneath the other end of the same level space. what has become of the missing strata? they have been carried away grain by grain by the denuding forces--by weathering, rain, frost, and fluviatile and marine action. the whole surface of a country is exposed to the abrading action of the subaërial forces, and has been carved by them into hills and valleys, the position of which depends partly upon the geological structure of the country, and partly upon the texture and composition of the rocks. the original slope of the surface, when it was first elevated out of the sea, would be determined by the action of the subterraneous forces--the dominant parts, whether table-lands or undulating ridges, forming the centres from which the waters would begin to flow. after the land had been subjected for many long ages to the wearing action of the denuding agents, it is evident that the softer rocks--those which were least capable of withstanding weathering and erosion--would be more worn away than the less easily decomposed masses. the latter would, therefore, tend to form elevations, and the former hollows. this is precisely what we find in nature. the great majority of isolated hills and hilly tracts owe their existence as such merely to the fact that they are formed of more durable materials than the rock-masses by which they are surrounded. when a line of dislocation is visible at the surface, it is simply because rocks of unequal durability have been brought into juxtaposition. the more easily denuded strata have wasted away to a greater extent than the tougher masses on the other side of the dislocation. nearly all elevations, therefore, may be looked upon as monuments of the denudation of the land; they form hills for the simple reason that they have been better able to withstand the attacks of the denuding agents than the rocks out of which the hollows have been eroded. . to this general rule there are exceptions, the most obvious being hills and mountains of volcanic origin, such as hecla, etna, vesuvius, &c., and, on a larger scale, the rocky ridge of the andes. again, it is evident that the great mountain-chains of the world are due in the first place to upheaval; but these mountains, as we now see them--peaks, cliffs, precipices, gorges, ravines--have been carved out of the solid block, as it were, by the ceaseless action of the subaërial forces. the direction of river-valleys has in like manner been determined in the first place by the original slope of the land; but the deep dells, the broad valleys and straths, have all been scooped out by running water. the northern highlands of scotland, for example, evidently formed at one time a broad table-land, elevated above the level of the sea by the subterranean forces. out of this old table-land the denuding agents, acting through untold ages, have carved out all the numerous ravines, glens, and valleys, the intervening ridges left behind now forming the mountains. it is true that now and again streams are found flowing in the direction of a fault, but that is simply because the dislocation is a line of weakness, along which it is easier for the denuding forces to act. for one fault that we find running parallel to the course of a river, we may observe hundreds cutting across its course at all angles. the great rocky basins occupied by lakes, which are so abundant in the mountainous districts of temperate regions and in northern latitudes, are believed to have been excavated by the erosive power of glacier-ice; and they point, therefore, to a time when our hemisphere must have been subjected to a climate severe enough to nourish massive glaciers in the british islands and similar latitudes. it may be concluded that the present physiography of the land is proximately due solely to the action of the denuding agents--rain, frost, rivers, and the sea. but the lines along which these agents act with greatest intensity have been determined in the first place by the subterranean forces which upheaved the solid crust into great table-lands or mountain undulations. both the remote and the proximate causes of the earth's surface-features, however, have acted in concert and contemporaneously, for no sooner would new land emerge above the sea-level than the breakers would assail it, and all the forces of the atmosphere would be brought to bear upon it--rain, frost, and rivers--so that the beginning of the sculpturing of hill and valley dates back to the period when the present lands were slowly emerging from the ocean. so great is the denudation of the land, that in process of time the whole would be planed down to the level of the sea, if it were not for the subterranean forces, which from time to time depress and elevate different portions of the earth's crust. it can be proved that strata miles in thickness have been removed bodily from the surface of our own country by the seemingly feeble agents of denudation. all the denuded material--mud, sand, and gravel--carried down into the sea has been re-arranged into new beds, and these have ever and anon been pushed up to the light of day, and scarped and channelled by the denuding forces, the resulting detritus being swept down as before into the sea, to form fresh deposits, and so on. it follows, therefore, that the present arrangement of land and sea has not always existed. there was a time before the present distribution of land obtained, and a time will yet arrive when, after infinite modifications of surface and level, the continents and islands may be entirely re-arranged, the sea replacing the land, and _vice versâ_. to trace the history of such changes in the past is one of the great aims of the scientific geologist. palÆontology.[f] [f] _palaios_, ancient, _onta_, beings, and _logos_, a discourse. . _fossils._--in our description of rock-masses, and again in our account of geological agencies, we referred to the fact that certain rocks are composed in large measure, or exclusively, of animal or vegetable organisms, or of both together; and we saw that analogous organic formations were being accumulated at the present time. but we have deferred to this place any special account of the organic remains which are entombed in rocks. _fossils_, as these are called, consist generally of the harder and more durable parts of animals and plants, such as bones, shells, teeth, seeds, bark, and ligneous tissues, &c. but it is usual to extend the term fossil to even the _casts_ or _impressions_ of such remains, and to foot-marks and tracks, whether of vertebrates, molluscs, crustaceans, or annelids. the organic remains met with in the rocks have usually undergone some chemical change. they have become _petrified_ wholly or in part. the gelatine which originally gave flexibility to some of them has disappeared, and even the carbonate and phosphate of lime of the harder parts have frequently been replaced by other mineral matter, by flint, pyrites, or the like. so perfect is the petrifaction in many cases, that the most minute structures have been entirely preserved--the original matter having been replaced atom by atom. as a rule, fossils occur most abundantly and in the best state in clay-rocks, like shale; while in porous rocks, like sandstone, they are generally poorly preserved, and not of so frequent occurrence. one reason for this is, that clay-rocks are much less pervious than sandstone, and their imbedded fossils have consequently escaped in greater measure the solvent powers of percolating water. but there are other reasons for the comparative paucity of fossils in arenaceous strata, as we shall see presently. . _proofs of varied physical conditions._--organic remains are either of terrestrial, fresh-water, or marine origin, and they are therefore of the utmost value to the geologist in deciphering the history of those great changes which have culminated in the present. but we can go a step further than this. we know that at the present day the distribution of animal and vegetable life is due to a variety of causes--to climatic and physical conditions. the creatures inhabiting arctic and temperate regions contrast strongly with those that tenant the tropics. so also we observe a change in animal and vegetable forms as we ascend from the low grounds of a country to its mountain heights. similar changes take place in the sea. the animals and plants of littoral regions differ from those whose habitat is in deeper water. now, the fossiliferous strata of our globe afford similar proofs of varying climatic and physical conditions. there are littoral deposits and deep-sea accumulations: the former are generally coarse-grained (conglomerates, grit, and sandstone); the latter are for the most part finer-grained (clay, shale, limestone, chalk, &c.); and both inshore and deep-water formations have each their peculiar organic remains. again, we know that some parts of the sea-bottom are not so prolific in life as others--where, for example, any considerable deposit of sand is taking place, or where sediment is being constantly washed to and fro upon the bottom, shells and other creatures do not appear in such numbers as where there is less commotion, and a finer and more equable deposit is taking place. it is partly for the same reason that certain rocks are more barren of organic remains than others. . _fossil genera and species frequently extinct._--it might perhaps at first be supposed that similar rocks would contain similar fossils. for example, we might expect that formations resembling in their origin those which are now forming in our coral seas would also, like the latter, contain corals in abundance, with some commingling of shells, crustaceans, fish, &c., such as are peculiar to the warm seas in which corals flourish. and this in some measure holds good. but when we examined carefully the fossils in certain of the limestones of our own country, we should find that while the same great orders and classes were actually present, yet the genera and species were frequently entirely different; and not only so, but that often none of these were now living on the earth. moreover, if we extended our research, we should soon discover that similar wide differences actually obtained between many of the limestones themselves and other fossiliferous strata of our country. . _fossiliferous strata of different ages._--another fact would also gradually dawn upon us--this, namely, that in certain rocks the fossils depart much more widely from analogous living forms, than the organic remains in certain other rocks do. the cause of this lies in the fact that the fossiliferous strata are of different ages; they have not all been formed at approximately the same time. on the contrary, they have been slowly amassed, as we have seen, during a long succession of eras. while they have been accumulating, great vicissitudes in the distribution of land and sea have taken place, climates have frequently altered, and the whole organic life of the globe has slowly changed again and again--successive races of plants and animals flourishing each for its allotted period, and then becoming extinct for ever.[g] thus, strata formed at approximately the same time contain generally the same fossils; while, on the other hand, sedimentary deposits accumulated at different periods are charged with different fossils. fossils in this way become invaluable to the geologist. they enable him to identify formations in separate districts, and to assign to them their relative antiquity.[h] if, for example, we have a series of formations, a, b, c, piled one on the top of the other, a being the lowest, and c the highest, and each charged with its own peculiar fossils, we may compare the fossils met with in other sets of strata with the organic remains found in a, b, c. should the former be found to correspond with the fossil contents of b, we conclude that the rocks in which they occur are approximately of contemporaneous origin with b, even although the equivalents of the formations a and c should be entirely wanting. further, we soon learn that the order of the series a, b, c, is never inverted. if a be the lowest, and c the highest stratum in one place, it is quite certain that the same order of succession will obtain wherever the equivalents of these strata happen to occur together. but the succession of strata is not invariably the same all the world over; in some countries, we may have dozens of separate formations piled one on the top of the other; in other countries, many members of the series are absent; in brief, _blanks in the succession_ are of constant occurrence. but by dovetailing, as it were, all the formations known to us, we are enabled to form a more or less complete series of rocks arranged in the order of their age. a little reflection will serve to shew that the partial mode in which the strata are distributed over the globe arises chiefly from two causes. we have to remember, _first_, that the deposits themselves were laid down only here and there in irregular spreads and patches--opposite the mouths of rivers, at various points along the ancient coast-lines, and over certain areas in the deeper abysses of the ocean--the coarser accumulations being of much less extent than those formed of finer materials. and, _second_, we must not forget the intense denudation which they have experienced, so that miles and miles of strata which once existed have been swept away, and their materials built up into new formations. [g] to this there are some exceptions. certain small foraminifers, for example, met with in some of the oldest formations, do not seem to differ from species which are still living. the genus _lingula_ (mollusca) has also come down from remotest ages, having outlived all its earlier associates. [h] this holds strictly true, however, only in regard to comparatively limited areas. the student must remember that strata occurring in widely separate regions of the earth, even although they contain very much the same assemblage of fossils, are not necessarily contemporaneous, in the strict meaning of the word; for the _fauna_ and _flora_ (the animal and plant life) may have died out, and become replaced by new forms more rapidly in one place than another. the term 'contemporaneous,' therefore, is a very lax one, and may sometimes group together deposits which, for aught that we can tell, may really have been accumulated at widely separated times. . _gradual extinction of species._--when a sufficient number of fossils has been diligently compared, we discover that those in the younger strata approach most nearly to the present living forms, and that the older the strata are, the more widely do their organic remains depart from existing types of animals and plants. we may notice also, that when a series of beds graduate up into each other, so that no strongly marked line separates the overlying from the underlying strata, there is also a similar gradation amongst the fossils. the fossils in the highest beds may differ entirely from those in the lowest; but in the middle beds there is an intermingling of forms. in short, it is evident that the creatures gradually became extinct, and were just as gradually replaced by new forms, until a time came when all the species that were living while the lowest beds were being amassed, at last died out, and a complete change was effected. . _proofs of cosmical changes of climate._--from the preceding remarks it will be also apparent that fossils teach us much regarding the climatology of past ages. they tell us how the area of the british islands has experienced many vicissitudes of climate, sometimes rejoicing in a warm or almost tropical temperature, at other times visited with a climate as severe as is now experienced in arctic and antarctic regions. not only so, but we learn from fossils that greenland once supported myrtles and other plants which are now only found growing under mild and genial climatic conditions; while, on the other hand, remains of arctic mammals are met with in the south of france. such great changes of climate are due, according to mr croll, to variations in the eccentricity of the earth's orbit combined with the precession of the equinox. it is well known that the orbit of our earth becomes much more elliptical at certain irregularly recurring periods than it is at present. during a period of extreme ellipticity, the earth is, of course, much further away from the sun in _aphelion_[i] than it is at a time of moderate ellipticity, while, in _perihelion_,[j] it is considerably nearer. now, let us suppose that, at a time when the ellipticity is great, the movement known as the precession of the equinox has changed the incidence of our seasons, so that our summer happens in perihelion and not in aphelion, while that of the southern hemisphere occurs in aphelion, and not, as at present, in perihelion. under such conditions, the climate of the globe would experience a complete change. in the northern hemisphere, so long and intensely cold would the winter be, that all the moisture that fell would fall as rain, and although the summer would be very warm, it would nevertheless be very short, and the heat then received would be insufficient to melt the snow and ice which had accumulated during the winter. thus gradually snow and ice would cover all the lands down to temperate latitudes. in the southern hemisphere, the reverse of all this would obtain. the winter there would be short and mild, and the summer, although cool, would be very long. but such changes would bring into action a whole series of physical agencies, every one of which would tend still further to increase the difference between the climates of the two hemispheres. owing to the vast accumulation of snow and ice in the northern hemisphere, the difference of temperature between equatorial and temperate and polar regions would be greater in that hemisphere than in the southern. hence the winds blowing from the north would be more powerful than those coming from the southern and warmer hemisphere, and consequently the warm water of the tropics would necessarily be impelled into the southern ocean. this would tend still further to lower the temperature of our hemisphere, while, at the same time, it would raise correspondingly the temperature at our antipodes. the general result would be, that in our hemisphere ice and snow would cover the ground down to low temperate latitudes--the british islands being completely smothered under a great sea of confluent glaciers. in the southern hemisphere, on the contrary, a kind of perennial summer would reign even up to the pole. such conditions would last for some ten or twelve thousand years, and then, owing to the precession of the equinox, a complete change would come about--the ice-cap would disappear from the north, and be replaced by continuous summer, while at the same time an excessively severe or glacial climate would characterise the south; and such great changes would occur several times during each prolonged epoch of great eccentricity. this, in few words, is an outline of mr croll's theory. that theory is at present _sub judice_, but there can be no doubt that it gives a reasonable explanation of many geological facts which have hitherto been inexplicable. of course, it is not maintained that all changes of climate are due directly or indirectly to astronomical causes. local changes of climate--changes affecting limited regions--may be induced by mutations of land and sea, resulting in the partial deflection of ocean currents, which are the chief secondary means employed by nature for the distribution of heat over the globe's surface. [i] _apo_, away from; _helios_, the sun. [j] _peri_, round about or near by; _helios_, the sun. from what has been stated in the foregoing paragraphs, it is clear that in our endeavours to decipher the geological history of our planet, palæontological must go hand in hand with stratigraphical evidence. we may indeed learn much from the mode of arrangement of the rocks themselves. but the test of superposition does not always avail us. it is often hard, and sometimes quite impossible, to tell from stratigraphical evidence which are the older rocks of a district. in the absence of fossils we must frequently be in doubt. but physical evidence alone will often afford us much and varied information. it will shew us what was land and what sea at some former period; it will indicate to us the sites of ancient igneous action; it will tell us of rivers, and lakes, and seas which have long since passed away. nay, in some cases, it will even convince us that certain great climatic changes have taken place, by pointing out to us the markings, and débris, and wandered blocks which are the sure traces of ice action, whether of glaciers or icebergs. the results obtained by combining physical and palæontological evidence form what is termed historical geology. historical geology. . the fossiliferous strata, as they are generally termed, have been chronologically arranged in a series of _formations_, each of which is characterised by its own peculiar suites of fossils. their relative age has been determined, as we have indicated above, by their fossils, and also by certain physical tests, the chief of these being _superposition_. it holds invariably true that a formation, a, found resting upon another series of strata, b, will always occur in precisely the same position, wherever these two deposits occur together. if b should appear in some place as resting upon a, we may be sure that the beds have been inverted during the contortion of the strata consequent upon subterranean action (see fig. , page ). again, another useful test of the relative age of strata lies in the circumstance that one is often made up or contains fragments of the other. in this case, then, it is quite clear which is the more recent accumulation. these tests have now been applied to the strata in many parts of the world, and the result is that geologists have been able to arrive at a chronological arrangement or classification, and so to construct a table shewing the relative position which would be occupied by all the different formations, if these occurred together in one place. in the british islands the long series of strata is well developed, but many of the formations are much more meagrely represented than their equivalents in other countries. but even when we attempt to fill up the blanks in our own series by dovetailing with them the strata of foreign countries, there yet remain numerous breaks in the succession, pointing to the fact that the stony record is a very fragmentary one at the best. no doubt there are many large tracts of the earth's surface which have not yet been investigated, and when these are known we may hope to have our knowledge greatly increased. but no one who reflects upon the mode of origin of the fossiliferous strata, and the wonderful mutations which the earth has undergone, can reasonably anticipate that a perfect and complete record of the geological history of our planet shall ever be compiled from the broken and fragmentary testimony of the rocks. . the following table gives the names of the different formations arranged in the order of their superposition, the youngest being at the top, and the oldest known at the bottom: iv. post-tertiary or quaternary-- historical or recent. pleistocene. iii. tertiary or cainozoic-- pliocene. miocene. eocene. ii. secondary or mesozoic-- cretaceous. jurassic. triassic. i. primary or palÆozoic-- permian. carboniferous. devonian and old red sandstone. silurian. cambrian. laurentian or pre-cambrian. . the primary formations are so called because they are the oldest known to us: they are not necessarily the first-formed aqueous deposits. dr hutton said truly: there is no trace of a beginning, and no signs of an end. in the primary or palÆozoic (ancient-life) formations are found the earliest traces of life. the forms as a rule depart very widely from those with which we are acquainted now. the _laurentian_ rocks have yielded only one fossil--a large foraminifer named _eozoon canadense_. the _cambrian_ formation contains but few fossils--crustaceans, molluscs, zoophytes, and worm-tracks. the _silurian_ strata are often abundantly fossiliferous. all the great classes of invertebrates are represented, and fish remains also occur. the _devonian_ and _old red sandstone_ are also characterised by the presence of an abundant fauna. in the old red sandstone are numerous fish remains; it appears to have been an estuarine or lacustrine deposit; the devonian, on the other hand, was marine, like the silurian and cambrian. the _carboniferous_ formation is the chief repository of coal in britain. it consists of terrestrial, fresh or brackish water, and marine deposits. the fauna and flora of the _permian_, which is partly a marine and partly a fresh-water formation, are allied, upon the whole, to those of the carboniferous, but offer at the same time many contrasts. . the secondary or mesozoic (middle-life) formations contain assemblages of fossils which do not depart so widely from analogous living forms as those belonging to palæozoic times. the _triassic_ strata yield abundance of rock-salt. in britain they contain very few fossils, but these are more abundant in the triassic deposits of foreign countries. the oldest known mammals first appear in this formation. the _jurassic_ formation is very highly fossiliferous. it is distinguished by the occurrence of numerous reptilian remains. nearly all the beds of this formation are marine, but there are associated with these the remains of a forest or old land surface, and a considerable accumulation of estuarine or fresh-water deposits; impure coals also occur in this formation. the _cretaceous_ strata are almost wholly marine, and chiefly of deep-water origin. but some land-plants are found, chiefly ferns, conifers, and cycads. near the base of the formation occurs a great river deposit (weald clay) with numerous remains of reptiles. . among the oldest strata of the tertiary or cainozoic (recent-life) division we meet with the _dawn_ of the existing state of the testaceous fauna--the _eocene_ (_eos_, dawn, and _kainos_, recent) containing three and a half per cent. of recent species among its shells. the proportion of recent species increases in the _miocene_ (_meion_, less, and _kainos_, recent), although the majority of the molluscs entombed in that formation belong to extinct species. in the _pliocene_ (_pleion_, more, and _kainos_, recent), however, the extinct species are in a minority. the post-tertiary or quaternary division comprises the concluding chapters of geological history. the _pleistocene_ (_pleistos_, most, and _kainos_, recent) contains no extinct species of shells, but a number of extinct mammalia. in the _recent_ deposits all the species of animals and plants are living. the tertiary and quaternary formations are partly of marine and partly of terrestrial and fresh-water origin. at the close of the tertiary period the 'glacial epoch' of pleistocene times began, and the british islands and a large part of northern europe and north america were then cased in snow and ice. traces of glacial conditions have also been met with in the eocene and miocene. the evidence furnished by palæozoic and mesozoic formations points chiefly to mild, genial, and sometimes tropical conditions. but traces of ice action are occasionally noted (namely, in the silurian, old red sandstone, carboniferous, permian, and cretaceous formations), pointing, perhaps, in some of the cases, to former alternations of cold and warm periods. indeed, the belief is now gaining ground, that the so-called glacial epoch of pleistocene times was not one long continuous age of ice, but rather consisted of an alternation of warm and cold periods. and it is not improbable, but highly likely, that similar alternations of climate have happened during every period of great eccentricity of the earth's orbit. questions. section . what is geology? . define the term _rock_. how many classes of rock are there? , , . into what groups are the mechanically formed rocks divided? define the terms _conglomerate_, _sandstone_, and _shale_. . what is the nature of the rocks belonging to the aërial or eolian group? . give an example of a chemically formed rock. . give examples of organically derived rocks. . what kinds of rocks are embraced by the metamorphic class? . what are igneous rocks? . what is the mineralogical composition of granite? . what is meant by a _mineral_? . name five minerals which do not contain oxygen. where does _fluor-spar_ occur? what is the element that enters most largely into the composition of the earth's crust? . name the forms under which the mineral _quartz_ occurs. name some of the oxides of iron. what is _iron pyrites_? . name two _sulphates_. name two _carbonates_. name some of the _silicates_. in what kinds of rock is _augite_ found? where does it never occur? in what kinds of rock does _hornblende_ usually occur? mention three species of felspar. what is one of the most distinguishing characteristics of mica? name three silicates of magnesia. mention some of their distinguishing peculiarities. where do _zeolites_ commonly occur? . what is a _quartzose conglomerate_? what is a _calcareous conglomerate_? . what is _grit_? what is _freestone_? to what are the various colours of sandstone due? what is _shale_? . name some typical eolian rocks, and tell where they occur. . how do _stalactites_ and _stalagmites_ occur? what is _siliceous sinter_, and how does it occur? how does _rock-salt_ occur? . mention some of the varieties of limestone. what is _cornstone_? what is the composition of _dolomite_? . name some of the varieties of coal. . what is _quartzite_? . describe _clay-slate_. . mention some altered limestones. . what are _schists_? name and give the mineralogical composition of three schists. . what is the general character of metamorphic rocks? . how would you classify granite? . what is the mineralogical composition of _syenite_ and _diorite_? . how do we distinguish the two groups into which igneous rocks are subdivided? what is meant by the terms _amygdaloidal_ and _porphyritic_? . name some rocks that belong to the acidic group. what is _quartz-porphyry_? . give examples of augitic igneous rocks. name a hornblendic igneous rock. . what are fragmental igneous rocks? what is the difference between _trappean breccia_ and _trappean conglomerate_? . what is meant by the terms _stratum_, _strata_, and _stratified_? what is the difference between _lamination_ and _bedding_? what is a section? . what is _false bedding_? . briefly describe the general appearance of _mud-cracks_ and _rain-prints_, and say how these have been formed. . what is meant by a _succession of strata_? . which kinds of stratified rocks generally have the greatest extension? . how do beds terminate? . how may planes of bedding sometimes indicate a break in the succession of strata? . what is the nature of _joints_? what are _master-joints_, and what is their probable cause? . what is _cleavage_, and what is its effect upon the bedding of rocks? . what is _foliation_? . give examples of concretionary rocks. what is the nature of chert and flint nodules? . define the terms _dip_ and _strike_. what is the _crop_ of a bed? what are _anticlines_ and _synclines_? . what is meant by an _inversion of strata_? . how does contemporaneous erosion indicate a pause in the deposition of a series of strata? . what is meant by _unconformability_? how does unconformability prove a lapse of time between the accumulation of the underlying and overlying strata? . what is _overlap_? . what is a _fault_? what is _hade_? how are the strata affected on either side of a fault? what is the appearance called _slickensides_? under what circumstances should we term a fault a _downthrow_? and when should we term it an _upcast_? how is the approximate age of a fault sometimes shewn? . what are metamorphic rocks, and what is their general appearance? in what districts of the british islands are they most abundantly developed? what are some of the appearances relied upon for distinguishing metamorphic from igneous granite? . how do igneous rocks occur? define what is meant by _contemporaneous_ and _subsequent_ or _intrusive_ igneous rocks. how does a contemporaneous igneous rock affect the beds upon which it rests? what is the character of the bed overlying a contemporaneous rock? what is the general structure of a contemporaneous igneous rock? what is meant by _vesicular structure_? what is the general texture of a contemporaneous igneous rock? what is the nature of the jointing in igneous rocks? what is _wacké_? . what is the nature of the beds of _breccia_, _conglomerate_, _ash_, and _tuff_, with which contemporaneous igneous rocks are often associated? what is a _neck_ of _volcanic agglomerate_? how are the strata affected at their junction with a 'neck'? . how do intrusive igneous rocks occur? how do intrusive _sheets_ occur? what effect have they produced upon the strata above and below them? what is a _dyke_? what relation do they occasionally bear to _sheets_ of igneous rock? what is a _neck_ of intrusive igneous rock, and how have the strata surrounding it been affected? . mention some of the contrasts between _intrusive_ and contemporaneous igneous rocks. what alteration is produced upon coal with which an intrusive sheet has come in contact? . what are _mineral veins_? what is the nature of the quartz veins in granite? how are the minerals usually arranged in the great metalliferous veins? what is a _pipe-vein_? . what are the great geological agents of change? . what is meant by _weathering_? how are rocks affected at the surface in tropical countries? what chemical effect has the atmosphere on calcareous rocks? how is soil formed? how are sand dunes formed? mention some effects of the transporting power of the atmosphere. . mention some of the chemical effects of interstitial water. what is the origin of _travertine_ or _calcareous tufa_? . how have _stalactites_ and _stalagmites_ been formed? give some instances of the solvent power of springs. . how are caves in limestone formed? describe some of the appearances of a country composed of calcareous rocks. describe briefly how a river erodes its channel. . describe the geological action of rain. . what do chemical analyses of river-water prove? give an example. what are pot-holes? give an example of the erosive power of running water. what amount of mud is carried in suspension by the mississippi, and discharged annually into the sea? what estimate has been formed of the total amount of mineral matter annually transported by that river? . what is _alluvium_? how is it formed? and mention some examples of its occurrence. . how is sediment deposited by a river in a lake? . what is the difference between lacustrine and fluvio-marine deposits? what is a _delta_? . describe the geological action of frost. describe the geological action of river-ice. . what are _glaciers_? what thickness do they attain in the alps? what is their rate of motion? what are _crevasses_, and how do they originate? what are _superficial moraines_? what are _terminal moraines_? what changes does a glacier effect upon its bed, and how are these modifications produced? what is the character of a glacial river? what is the origin of _icebergs_? how is the general absence of blocks and stones in greenland icebergs to be explained? what is the nature of a submarine terminal moraine? what is the _ice-foot_? what is the chief agent in distributing erratic stones and blocks over the sea-bottom? what effect upon the sea-bed must stranding icebergs produce? . what are some of the chemical compounds held in solution in sea-water? which of these go to form the shells and skeletons of marine animals? . describe the action of breakers on a sea-coast. how does frost aid the wasting action of breakers? what effect has the nature of the rocks in the production of inequalities in a coast-line? upon what part of the sea-bottom does the material derived by the action of the breakers chiefly accumulate? what effect have the tides and ocean currents in the distribution of sediment? . what is the general rule as regards fine-grained and coarse-grained deposits? mention a partial exception to this rule. what effect have tidal currents in shallow seas? . how are rocks disintegrated through the action of plants? what is peat? what may be inferred from the occurrence of shell-marl underneath peat? what does the appearance of roots and trunks of trees, and of remains of land animals under peat, indicate? . what, generally, is the geological action of animal life? . what is coral? what is a _fringing_ reef? what is the general character of a _barrier_ reef? give an example of one. what is an _atoll_? what is the nature of coral rock? what is mr darwin's theory of the formation of coral reefs? . what is the nature of the atlantic ooze? in what respects may it eventually come to resemble chalk and limestone? mention an instance of the abundant occurrence in the sea of animalcules with siliceous coverings and skeletons. what is the nature of the red clay found at great depths in the atlantic and southern oceans? . what are some of the notions held in regard to the internal condition of the earth? at what (average) rate does the temperature of the earth's crust increase as we descend from the surface? . what is the nature of the movements to which the earth's crust is subjected? . describe the hypotheses advanced to account for earthquakes. mention some of the effects of earthquakes-- _st_, as regards alterations of level; and _d_, as regards modifications of the surface. . mention a good example of tranquil elevation and depression of the earth's crust. mention some of the proofs of an elevatory movement. give proofs that shew depression of the land. how may certain former changes of sea-level be accounted for without inferring any movement of the land? . what effect must _depression_ have upon the strata forming the earth's crust? what is the result of a movement of elevation? what is the cause of _cleavage_? . what is the nature of the materials thrown out during volcanic eruptions? what is the general structure of a volcanic cone? how does molten rock make its escape from the orifice of eruption? what is the meaning of the terms _lapillo_, _puzzolana_, and _ceneri_? . what is lava? describe the general appearance and mode of progression of a stream of lava. what effect is produced upon fragments of rock caught up and inclosed in lava; and what changes are caused in the pavement upon which it cools? how does a lava stream entering a lake or the sea behave in regard to the sediment gathering therein? to what is the basaltic structure due? how are the axes of the prisms in a columnar igneous rock arranged? name some of the varieties of lava. what is the origin of the vesicular structure in igneous rocks? what portions of a bed of lava are most frequently scoriaceous? in what kinds of lava is the vesicular structure most abundantly met with? how have the vesicles become flattened? in what manner have they been filled with mineral matter? what is the origin of the dykes of modern volcanic districts? . how is metamorphism on the large scale supposed to have been induced? how may granite be at one and the same time a metamorphic and igneous rock? . mention some of the views held with regard to the origin of mineral veins. . what is _denudation_? how do inclined strata prove that the strata have been denuded? how do _faults_ afford proof of denudation? what have been the general effects produced by denudation on the face of the land? . what part have the subterranean forces acted in the formation of mountains? to what geological action is the present aspect of these mountains due? what has determined the direction of river valleys? how have the valleys, dells, &c. been formed? what effect have faults had in determining the direction of river valleys? what is supposed to be the origin of the deep rock-basins occupied by many fresh-water lakes? how is the waste of land by denudation compensated? . what are _fossils_? what is meant by _petrifaction_? in what kind of rocks do fossils occur most abundantly, and in the best state of preservation? and what reason can be given for this? . how do fossils afford proof of varied physical conditions? give a reason for some rocks being more barren of fossils than others. . state some of the characters which distinguish broadly the older fossiliferous strata from those similar accumulations which are being formed in our own day. . how may we identify formations in separate districts? how is the interrupted and partial distribution of strata to be accounted for? . in what respect do the fossils in younger strata differ from those in older strata? what general proof can be adduced to shew that species have become gradually extinct? . give an instance how fossils prove changes of climate in the past. what is supposed to be the cause of great cosmical changes of climate? describe mr croll's theory of cosmical changes of climate. . what is the test of _superposition_? mention another test of the relative age of strata. . name the four great divisions under which the fossiliferous rocks are arranged. . name the primary or palæozoic formations. what are the principal kinds of fossils found in the old red sandstone? which formation is the chief repository of coal in britain? . in what other formations do coals occur? in which formation do the oldest known mammals occur? name the secondary formations. . name the tertiary formations. what kind of climate characterised the northern hemisphere at the beginning of pleistocene times? what kinds of climate would appear from the evidence to have chiefly prevailed in primary, secondary, and tertiary ages? have we any trace of frigid conditions during these ages? what is the growing opinion with regard to the climatic conditions during the glacial period of pleistocene times? the end. edinburgh: printed by w. & r. chambers. * * * * * * * transcriber's notes the only minor correction that was noted in converting this document from a printed version into an electronic version was an unpaired parenthesis on the first line of the title page. * * * * * * * dragons of the air [illustration: fig. . rhamphorhynchus phyllunus showing the preservation of the wing membranes _from the lithographic slate of eichstädt, bavaria_ _frontispiece_] dragons of the air an account of extinct flying reptiles by h. g. seeley, f.r.s. professor of geology in king's college, london; lecturer on geology and mineralogy in the royal indian engineering college with eighty illustrations "i am a brother of dragons" _job_ xxx. new york: d. appleton & co. london: methuen & co. preface i was a student of law at a time when sir richard owen was lecturing on extinct fossil reptiles. the skill of the great master, who built bones together as a child builds with a box of bricks, taught me that the laws which determine the forms of animals were less understood at that time than the laws which govern the relations of men in their country. the laws of nature promised a better return of new knowledge for reasonable study. a lecture on flying reptiles determined me to attempt to fathom the mysteries which gave new types of life to the earth and afterwards took them away. thus i became the very humble servant of the dragons of the air. knowing but little about them i went to cambridge, and for ten years worked with the professor of geology, the late rev. adam sedgwick, ll.d., f.r.s., in gathering their bones from the so-called cambridge coprolite bed, the cambridge greensand. the bones came in thousands, battered and broken, but instructive as better materials might not have been. my rooms became filled with remains of existing birds, lizards, and mammals, which threw light on the astonishing collection of old bones which i assisted in bringing together for the university. in time i had something to say about flying animals which was new. the story was told in the theatre of the royal institution, in a series of lectures. some of them were repeated in several english towns. there was still much to learn of foreign forms of flying animals; but at last, with the aid of the government grant administered by the royal society, and the chiefs of the great continental museums, i saw all the specimens in europe. so i have again written out my lectures, with the aid of the latest discoveries, and the story of animal structure has lost nothing in interest as a twice-told tale. it still presents in epitome the story of life on the earth. he who understands whence the flying reptiles came, how they endured, and disappeared from the earth, has solved some of the greatest mysteries of life. i have only contributed something towards solving the problems. in telling my story, chiefly of facts in nature, an attempt is made to show how a naturalist does his work, in the hope that perhaps a few readers will find happiness in following the workings of the laws of life. such an illumination has proved to many worth seeking, a solid return for labour, which is not to be marketed on the exchange, but may be taken freely without exhausting the treasury of nature's truths. such outlines of knowledge as here are offered to a larger public, may also, i believe, be acceptable to students of science and scientific men. the drawings given in illustration of the text have been made for me by miss e. b. seeley. h. g. s. kensington, _may, _ contents page chapter i. flying reptiles chapter ii. how a reptile is known chapter iii. a reptile is known by its bones chapter iv. animals which fly chapter v. discovery of the pterodactyle chapter vi. how animals are interpreted by their bones chapter vii. interpretation of pterodactyles by their soft parts chapter viii. the plan of the skeleton chapter ix. the backbone, or vertebral column chapter x. the hip-girdle and hind limb chapter xi. shoulder-girdle and fore limb chapter xii. evidences of the animal's habits from its remains chapter xiii. ancient ornithosaurs from the lias chapter xiv. ornithosaurs from the middle secondary rocks chapter xv. ornithosaurs from the upper secondary rocks chapter xvi. classification of the ornithosauria chapter xvii. family relations of pterodactyles to animals which lived with them chapter xviii. how pterodactyles may have originated appendix index list of illustrations fig. page . wings of rhamphorhynchus _frontispiece_ . lung of the lung-fish ceratodus . attachment of the lower jaw in a mammal and in a pterodactyle . chaldæan dragon . winged human figure from the temple of ephesus . flying fish exocoetus . flying frog . flying lizard (draco) . birds in flight . flying squirrel (pteromys) . bats, flying and walking . skeleton of _pterodactylus longirostris_ . the skeleton restored . the animal form restored . fore limbs in four types of mammals . pneumatic foramen in pterodactyle bone . lungs of the bird apteryx . air cells in the body of an ostrich . lung of a chameleon . brain in pterodactyle, mammal, bird, and reptiles . skull of kingfisher and rhamphorhynchus . skull of heron and rhamphorhynchus . palate of macrocercus and ? campylognathus . lower jaw of echidna and ornithostoma . first two neck vertebræ of ornithocheirus . middle neck vertebræ of ornithocheirus . back vertebra of ornithocheirus and crocodile . sacrum, with hip bones, of rhamphorhynchus . extremity of tail of _rhamphorhynchus phyllurus_ . hip-girdle bones in apteryx and rhamphorhynchus . pelvis with prepubic bone in pterodactylus . pelvis with prepubic bones in rhamphorhynchus . pelvis of an alligator seen from below . femora: echidna, ornithocheirus, ursus . tibia and fibula: dimorphodon and vulture . metatarsus and digits in three pterodactyles . sternum in cormorant and rhamphorhynchus . sternum in ornithocheirus . shoulder-girdle bones in a bird and three pterodactyles . the notarium from the back of ornithocheirus . the shoulder-girdle of ornithocheirus . humerus of pigeon and ornithocheirus . fore-arm of golden eagle and dimorphodon . wrist bones of ornithocheirus . clawed digits of the hand in two pterodactyles . claw from the hand of ornithocheirus . the hand in archæopteryx and the ostrich . slab of lias with bones of dimorphodon _to face page_ . dimorphodon (restored form) at rest . dimorphodon (restored form of the animal) _to face page_ . dimorphodon skeleton, walking as a quadruped " " . dimorphodon skeleton as a biped " " . lower jaw of dorygnathus . dimorphodon (wing membranes spread for flight) _to face page_ . pelvis of dimorphodon . rhamphorhynchus skeleton (restored) . scaphognathus (restoration of ) . six restorations of ornithosaurs . ptenodracon skeleton (restored) . _cycnorhamphus suevicus_ slab with bones _to face page_ . _cycnorhamphus suevicus_ (form of the animal) _to face page_ . _cycnorhamphus suevicus_ skeleton (restored) . _cycnorhamphus fraasi_ (restored skeleton form of the animal) _to face page_ . _cycnorhamphus fraasi_ (restoration of the form of the body) _to face page_ . neck vertebra of doratorhynchus from the purbeck . neck bone of ornithodesmus from the wealden . sternum of ornithodesmus, seen from the front . sternum of ornithodesmus, side view, showing the keel . diagram of known parts of skull of ornithocheirus . neck bone of ornithocheirus . jaws of ornithocheirus from the chalk . palate of the english toothless pterodactyle . two views of the skull of ornithostoma (pteranodon) . skeleton of ornithostoma . comparison of six skulls of ornithosaurs . pelvis of ornithostoma . skull of anchisaurus and dimorphodon . skull of ornithosuchus and dimorphodon . the pelvis in ornithosaur and dinosaur . the prepubic bones in dimorphodon and iguanodon these figures are greatly reduced in size, and when two or more bones are shown in the same figure all are brought to the same size to facilitate the comparison. dragons of the air chapter i flying reptiles the history of life on the earth during the epochs of geological time unfolds no more wonderful discovery among types of animals which have become extinct than the family of fossils known as flying reptiles. its coming into existence, its structure, and passing away from the living world are among the great mysteries of nature. the animals are astonishing in their plan of construction. in aspect they are unlike birds and beasts which, in this age, hover over land and sea. they gather into themselves in the body of a single individual, structures which, at the present day, are among the most distinctive characters of certain mammals, birds, and reptiles. the name "flying reptile" expresses this anomaly. its invention is due to the genius of the great french naturalist cuvier, who was the first to realise that this extinct animal, entombed in slabs of stone, is one of the wonders of the world. the word "reptile" has impressed the imagination with unpleasant sound, even when the habits of the animals it indicates are unknown. it is familiarly associated with life which is reputed venomous, and is creeping and cold. its common type, the serpent, in many parts of the world takes a yearly toll of victims from man and beast, and has become the representative of silent, active strength, dreaded craft, and danger. science uses the word "reptile" in a more exact way, to define the assemblage of cold-blooded animals which in familiar description are separately named serpents, lizards, turtles, hatteria, and crocodiles. turtles and the rest of them survive from great geological antiquity. they present from age to age diversity of aspect and habit, and in unexpected differences of outward proportion of the body show how the laws of life have preserved each animal type. for the vital organs which constitute each animal a reptile, and the distinctive bony structures with which they are associated, remain unaffected, or but little modified, by the animal's external change in appearance. the creeping reptile is commonly imagined as the antithesis of the bird. for the bird overcomes the forces that hold even man to the earth, and enjoys exalted aerial conditions of life. therefore the marvel is shared equally by learned and unlearned, that the power of flight should have been an endowment of animals sprung from the breed of serpents, or crocodiles, enabling them to move through the air as though they too were of a heaven-born race. the wonder would not be lessened if the animal were a degraded representative of a nobler type, or if it should be demonstrated that even beasts have advanced in the battle of life. the winged reptile, when compared with a bird, is not less astounding than the poetic conceptions in milton's _paradise lost_ of degradation which overtakes life that once was amongst the highest. and on the other hand, from the point of view of the teaching of darwin in the theories of modern science, we are led to ask whether a flying reptile may not be evidence of the physical exaltation which raises animals in the scale of organisation. the dominance upon the earth of flying reptiles during the great middle period of geological history will long engage the interest of those who can realise the complexity of its structure, or care to unravel the meaning of the procession of animal forms in successive geological ages which preceded the coming of man. the outer vesture of an animal counts for little in estimating the value of ties which bind orders of animals together, which are included in the larger classes of life. the kindred relationship which makes the snake of the same class as the tortoise is determined by the soft vital organs--brain, heart, lungs--which are the essentials of an animal's existence and control its way of life. the wonder which science weaves into the meaning of the word "reptile," "bird," or "mammal," is partly in exhibiting minor changes of character in those organs and other soft parts, but far more in showing that while they endure unchanged, the hard parts of the skeleton are modified in many ways. for the bones of the reptile orders stretch their affinities in one direction towards the skeletons of salamanders and fishes; and extend them also at the same time in other directions, towards birds and mammals. this mystery we may hope to partly unravel. chapter ii how a reptile is known definition of reptiles by their vital organs the relations of reptiles to other animals may be stated so as to make evident the characters and affinities which bind them together. early in the nineteenth century naturalists included with the reptilia the tribe of salamanders and frogs which are named amphibia. the two groups have been separated from each other because the young of amphibia pass through a tadpole stage of development. they then breathe by gills, like fishes, taking oxygen from the air which is suspended in water, before lungs are acquired which afterwards enable the animals to take oxygen directly from the air. the amphibian sometimes sheds the gills, and leaves the water to live on land. sometimes gills and lungs are retained through life in the same individual. this amphibian condition of lung and gill being present at the same time is paralleled by a few fishes which still exist, like the australian _ceratodus_, the lung-fish, an ancient type of fish which belongs to early days in geological time. this metamorphosis has been held to separate the amphibian type from the reptile because no existing reptile develops gills or undergoes a metamorphosis. yet the character may not be more important as a ground for classification than the community of gills and lungs in the fish and amphibian is ground for putting them together in one natural group. for although no gills are found in reptiles, birds, or mammals, the embryo of each in an early stage of development appears to possess gill-arches, and gill-clefts between them, through which gills might have been developed, even in the higher vertebrates, if the conditions of life had been favourable to such modification of structure. in their bones reptiles and amphibia have much in common. nearly all true reptiles lay eggs, which are defined like those of birds by comparatively large size, and are contained in shells. this condition is not usual in amphibians or fishes. when hatched the young reptile is completely formed, the image of its parent, and has no need to grow a covering to its skin like some birds, or shed its tail like some tadpoles. the reptile is like the bird in freedom from important changes of form after the egg is hatched; and the only structure shed by both is the little horn upon the nose, with which the embryo breaks the shell and emerges a reptile or a bird, growing to maturity with small subsequent variations in the proportions of the body. [illustration: fig. lung of the fish ceratodus partly laid open to show its chambered structure (after günther)] the reptile skin between one class of animals and another the differences in the condition of the skin are more or less distinctive. in a few amphibians there are some bones in the skin on the under side of the body, though the skin is usually naked, and in frogs is said to transmit air to the blood, so as to exercise a respiratory function of a minor kind. this naked condition, so unlike the armoured skin of the true reptilia, appears to have been paralleled by a number of extinct groups of fossils of the secondary rocks, such as ichthyosaurs and plesiosaurs, which were aquatic, and probably also by some dinosauria, which were terrestrial. living reptiles are usually defended with some kind of protection to the skin. among snakes and lizards the skin has commonly a covering of overlapping scales, usually of horny or bony texture. the tortoise and turtle tribe shut up the animal in a true box of bone, which is cased with an armour of horny plates. crocodiles have a thick skin embedding a less continuous coat of mail. thus the skin of a reptile does not at first suggest anything which might become an organ of flight; and its dermal appendages, or scales, may seem further removed from the feathers which ensure flying powers to the bird than from the naked skin of a frog. the reptile brain although the mode of development of the young and the covering of the skin are conspicuous among important characters by which animals are classified, the brain is an organ of some importance, although of greater weight in the higher vertebrata than in its lower groups. reptiles have links in the mode of arrangement of the parts of their brains with fishes and amphibians. the regions of that organ are commonly arranged in pairs of nervous masses, known as ( ) the olfactory lobes, ( ) the cerebrum, behind which is the minute pineal body, followed by ( ) the pair of optic lobes, and hindermost of all ( ) the single mass termed the cerebellum. these parts of the brain are extended in longitudinal order, one behind the other in all three groups. the olfactory lobes of the brain in fishes may be as large as the cerebrum; but among reptiles and amphibians they are relatively smaller, and they assume more of the condition found in mammals like the hare or mole, being altogether subordinate in size. and the cerebral masses begin to be wider and higher than the other parts of the brain, though they do not extend forward above the olfactory lobes, as is often seen in mammals. in crocodiles the cerebral hemispheres have a tendency to a broad circular form. among chelonian reptiles that region of the brain is more remarkable for height. lizards and ophidians both have this part of the brain somewhat pear-shaped, pointed in front, and elongated. the amphibian brain only differs from the lizard type in degree; and differences between lizards' and amphibian brains are less noticeable than between the other orders of reptiles. the reptilian brain is easily distinguished from that of all other animals by the position and proportions of its regions (see fig. , p. ). birds have the parts of the brain formed and arranged in a way that is equally distinctive. the cerebral lobes are relatively large and convex, and deserve the descriptive name "hemispheres." they are always smooth, as among the lower mammals, and extend backward so as to abut against the hind brain, termed the cerebellum. this junction is brought about in a peculiar way. the cerebral hemispheres in a bird do not extend backward to override the optic lobes, and hide them, as occurs among adult mammals, but they extend back between the optic lobes, so as to force them apart and push them aside, downward and backward, till they extend laterally beyond the junction of the cerebrum with the cerebellum. the brain of a bird is never reptilian; but in the young mammal the brain has a very reptilian aspect, because both have their parts primarily arranged in a line. therefore the brain appears to determine the boundary between bird and reptile exactly. reptilian breathing organs the breathing organs of birds and reptiles which are associated with these different types of brain are not quite the same. the frog has a cellular lung which, in the details of the minute sacs which branch and cluster at the terminations of the tubes, is not unlike the condition in a mammal. in a mammal respiration is aided by the bellows-like action of the muscles connected with the ribs, which encase the cavity where the lungs are placed, and this structure is absent in the frog and its allies. the frog, on the other hand, has to swallow air in much the same way as man swallows water. the air is similarly grasped by the muscles, and conveyed by them downward to the lungs. therefore a frog keeps its mouth shut, and the animal dies from want of air if its mouth is open for a few minutes. crocodiles commonly lie in the sun with their mouths widely open. the lungs in both crocodiles and turtles are moderately dense, traversed by great bronchial tubes, but do not differ essentially in plan from those of a frog, though the great branches of the bronchial tubes are stronger, and the air chambers into which the lung is divided are somewhat smaller. the new zealand hatteria has the lungs of this cellular type, though rather resembling the amphibian than the crocodile. the lungs during life in all these animals attain considerable size, the maximum dimensions being found in the terrestrial tortoises, which owe much of their elevated bulk to the dimensions of the air cells which form the lungs. the lungs of serpents and lizards are formed on a different plan. in both those groups of reptiles the dense cellular tissue is limited to the part of the lung which is nearest to the throat. this network of blood vessels and air cells extends about the principal bronchial tube much as in other animals, but as it extends backward the blood vessels become few until the _tubular_ lung appears in its hinder part, as it extends down the body, almost as simple in structure as the air bladder of a fish. among serpents only one of these tubular lungs is commonly present, and the structure has a less efficient appearance as a breathing organ than the single lung of the fish _ceratodus_ (fig. ). the chameleons are a group of lizards which differ in many ways from most of their nearest kindred, and the lungs, while conforming in general plan to the lizard type in being dense at the throat, and a tubular bladder in the body, give off on both sides a number of short lateral branches like the fingers of a glove (fig. , p. ). thus the breathing organs of reptiles present two or three distinct types which have caused serpents and lizards to be associated in one group by most naturalists who have studied their anatomy; while crocodiles and chelonians represent a type of lung which is quite different, and in those groups has much in common. these characters of the breathing organs contribute to separate the cold-blooded armoured reptiles from the warm-blooded birds clothed with feathers, as well as from the warm-blooded mammals which suckle their young; for both these higher groups have denser and more elastic spongy lung tissue. it will be seen hereafter that many birds in the most active development of their breathing organs substantially revert to the condition of the serpent or chameleon in a somewhat modified way. because, instead of having one great bronchial tube expanded to form a vast reservoir of air which can be discharged from the lung in which the reptile has accumulated it, the bird has the lateral branches of the bronchial tubes prolonged so as to pierce the walls of the lung, when its covering membrane expands to form many air cells, which fill much of the cavity of the bird's body (see fig. ). thus the bird appears to combine the characters of such a lung as that of a crocodile, with a condition which has some analogy with the lung of a chameleon. it is this link of structure of the breathing organs between reptiles and birds that constitutes one of the chief interests of flying reptiles, for they prove to have possessed air cells prolonged from the lungs, which extended into the bones. chapter iii a reptile is known by its bones such are a few illustrations of ways in which reptiles resemble other animals, and differ from them, in the organs by means of which the classification of animals is made. but such an idea is incomplete without noticing that the bony framework of the body associated with such vital organs also shows in its chief parts that reptiles are easily recognised by their bones. i will therefore briefly state how reptiles are defined in some regions of the skeleton, for in tracing the history of reptile life the bones are the principal remains of animals preserved in the rocks; and the soft organs which have perished can only be inferred to have been present from the persistence of durable characteristic parts of the skeleton, which are associated with those soft organs in animals which exist at the present day, and are unknown in other animals in which the skeleton is different. the hang of the lower jaw the manner in which the lower jaw is connected with the skull yields one of the most easily recognised differences between the great groups of vertebrate animals. _in mammals._--in every mammal--such as the dog or sheep--the lower jaw, which is formed of one bone on each side, joins directly on to the head of the animal, and moves upon a bone of the skull which is named the temporal bone. this character is sufficient to prove, by the law of association of soft and hard parts of the body, that such an animal had warm blood and suckled its young. [illustration: fig. _pterodactylus kochi_ skull of bear comparison to show the articulation with the lower jaw in a mammal and _pterodactylus kochi_. the quadrate bone is lettered q in this pterodactyle, and comes between the skull and the lower jaw like the quadrate bone in a bird and in lizards.] _in birds._--in birds a great difference is found in this region of the head. the temporal bone, which it will be more convenient to name the squamosal bone, from its squamous or scale-like form, is still a part of the brain case, and assists in covering the brain itself, exactly as among mammals. but the lower jaw is now made up of five or six bones. and between the hindermost and the squamosal there is an intervening bar of bone, unknown among mammalia, which moves upon the skull by a joint, just as the lower jaw moves upon it. this movable bone unites with parts of the palate and the face, and is known as the quadrate bone. its presence proves that the animal possessing it laid eggs, and if the face bones join its outer border just above the lower jaw, it proves that the animal possessed hot blood. _in reptiles._--all reptiles are also regarded as possessing the quadrate bone. but the squamosal bone with which it always unites is in less close union with the brain case, and never covers the brain itself. serpents show an extreme divergence in this condition from birds, for the squamosal bone appears to be a loose external plate of bone which rests upon the compact brain case and gives attachment to the quadrate bone which is as free as in a bird. among lizards the quadrate bone is usually almost as free. in the other division of existing reptilia, including crocodiles, the new zealand lizard-like reptile hatteria, called tuatera, and turtles, the squamosal and quadrate bones are firmly united with the bones of the brain case, face, and palate, so that the quadrate bone has no movement; and the same condition appears in amphibians, such as toads and frogs. with these conditions of the quadrate bone are associated cold blood, terrestrial life, and young developed from eggs. _in fishes._--bony fishes, and all others in which separate bones build up the skull, differ from reptiles and birds much as those animals differ from mammals. the union of the lower jaw with the skull becomes complicated by the presence of additional bones. the quadrate bone still forms a pulley articulation upon which the lower jaw works, but between it and the squamosal bone is the characteristic bone of the fish known as the hyomandibular, commonly connected with opercular bones and metapterygoid which intervene, and help to unite the quadrate with the brain case. in the cartilaginous fishes there is only one bone connecting the jaws with the skull on each side. this appears to prove that just as the structure of the arch of bones suspending the jaw may be complicated by the mysterious process called segmentation, which separates a bone into portions, so simplification and variation may result because the primitive divisions of the material cease to be made which exists before bones are formed. the principal regions of the skull and skeleton all vary in the chief groups of animals with backbones; so that the reptile may be recognised among fossils, even in extinct groups of animals and occasionally restored from a fragment, to the aspect which characterised it while it lived. chapter iv animals which fly the nature of a reptile is now sufficiently intelligible for something to be said concerning flight, and structures by means of which some animals lift themselves in the air. it is not without interest to remember that, from the earliest periods in human records, representations have been made of animals which were furnished with wings, yet walked upon four feet, and in their typical aspect have the head shaped like that of a bird. they are commonly named dragons. flying dragons [illustration: fig. from _the battle between bel and the dragon_] the effigy of the dragon survives to the present day in the figure over which st. george triumphs, on the reverse of the british sovereign. in the luxuriant imaginations of ancient eastern peoples, dating back to prehistoric ages, perhaps b.c., the dragons present an astonishing constancy of form. in after-times they underwent a curious evolution, as the conception of babylon and egypt is traced through assyria to greece. the wings, which had been associated at first with the fore limb of the typical dragon, become characteristic of the lion, and of the poet's winged horse, and finally of the human figure itself, carved on the great columns of the greek temples of ephesus. these flying animals are historically descendants of the same common stock with the dragons of china and japan, which still preserve the aspect of reptiles. their interest is chiefly in evidence of a latent spirit of evolution in days too remote for its meaning to be now understood, which has carried the winged forms higher and ever higher in grade of organisation, till their wings ceased to be associated with feelings of terror. the hebrew cherubim are regarded by h. e. ryle, bishop of exeter, as probably dragons, and the figure of the conventional angel is the human form of the dragon. [illustration: fig. . figure from the temple of ephesus] organs of flight turning from this reference to the realm of mythology to existing nature, the power of flight is popularly associated with all the chief types of vertebrate animals--fishes, frogs, lizards, birds, and mammals. many of the animals ill deserve the name of flyers, and most are exceptions to different conditions of existence which control their kindred, but it is convenient to examine for a little the nature of the structures by which this movement in the air, which is not always flight, is made possible. certain fishes, like the lung-fish ceratodus, of queensland, and the mud-fish lepidosiren, are capable of leaving the water and living on land, and for a time breathe air. but neither these fishes nor periophthalmus, which runs with rapid movement of its fins and carries the body more or less out of water, or the climbing perch, anabas, carried out of water over the country by indian jugglers, ever put on the slightest approach to wings. flying fishes [illustration: fig. . the flying fish exocoetus with the fins extended moving through the air] the flight of fishes is a kind of parachute support not unlike that by which a folded paper is made to travel in the air. it is chiefly seen in the numerous species of a genus exocoetus, allied to the gar-pike (belone), which is common in tropical seas, and usually from a foot to eighteen inches long. they emerge from the water, and for a time support themselves in the air by means of the greatly developed breast fins, which sometimes extend backward to the tail fin. although these fins appear to correspond to the fore limbs of other animals, they may not be moved at the will of the fish like the wing of a bird. when the flying fishes are seen in shoals in the vicinity of ships, those fins remain extended, so that the fish is said sometimes to travel yards at a speed of fifteen miles an hour, rising twenty feet or more above the surface of the sea, travelling in a straight line, though sometimes influenced by the wind. here the organ, which is at once a fin and a wing, consists of a number of thin long rods, or rays, which are connected by membrane, and vary in length to form an outline not unlike the wing of a bird which tapers to a point. the interest of these animals is chiefly in the fact that flight is separated from the condition of having lungs with which it is associated in birds, for although the flying fish has an air bladder, there is no duct to connect it with the throat. flying frogs [illustration: fig. . the flying frog (rhacophorus) the membranes of the foot and hand extend between the metatarsal and metacarpal bones, as well as the bones of the digits.] among amphibians the organs of flight are also of a parachute kind, but of a different nature. they are seen in certain frogs which frequent trees, and are limited to membranes which extend between the diverging digits of the hand and foot, forming webs as fully developed as in the foot of a swimming bird. as these frogs leap, the membranes are expanded and help to support the weight of the body, so that the animal descends more easily as it moves from branch to branch. there is no evidence that the bones of the digits ever became elongated like the fin rays of the flying fish or the wing bones of a bat; but the web suggests the basis of such a wing, and the possibilities under which wings may first originate, by elongation of the bones of a webbed hand like that of a flying frog. flying lizards [illustration: fig. . the flying dragon, draco forming a parachute by means of the extended ribs] the reptilia in their several orders are remarkable for absence of any modification of the arms which might suggest a capacity for acquiring wings, as being latent in their organisation. crocodiles, tortoises, and serpents are alike of the earth, and not of the air. but among lizards there are small groups of animals in which a limited capacity for movement through the air is developed. it is best known in the family of small lizards named dragons, represented typically by the species _draco volans_ found in the oriental region of the east indies and malay archipelago. the organ of flight is produced in an unexpected way, by means of the ribs instead of the limbs. the ribs extend outward as far as the arms can stretch, and the first five or six are prolonged beyond the body so as to spread a fold of skin on each side between the arm and the leg. the membrane admits of some movement with the ribs. this arrangement forms a parachute, which enables the animal to move rapidly among branches of trees, extending the structure at will, so that it is used with rapidity too quick to be followed by the eye, as it leaps through considerable distances. a less singular aid to movement in the air is found in some of the lizards termed geckos. the so-called flying gecko (_platydactylus homalocephalus_) has a fringe unconnected with ribs, which extends laterally on the sides of the body and tail, as well as at the back and front of the fore and hind limbs, and between the digits, where the web is sometimes almost as well developed as among tree frogs. this is essentially a lateral horizontal frill, extending round the body. its chief interest is in the circumstance that it includes a membrane which extends between the wrist bones and the shoulder on the front of the arm. that is the only part of the fringe which represents the wing membrane of a bird. the fossil flying reptiles have not only that membrane, but the lateral membranes at the sides of the body and behind the arms. other lizards have the skin developed in the direction of the circumference of the body. in the australian chlamydosaurus it forms an immense frill round the neck like a mediæval collar. but though such an adornment might break a fall, it could not be regarded as an organ of flight. flying birds [illustration: fig. . position of birds in flight] the wings of birds, when they are developed so as to minister to flight, are all made upon one plan; but as examples of the variation which the organs contributing to make the fore limb manifest, i may instance the short swimming limb of the penguin, the practically useless rudiment of a wing found in the ostrich or kiwi, and the fully developed wing of the pigeon. the wings of birds obtain an extensive surface to support the animal by muscular movements of three modifications of structure. first, the bones of the fore limb are so shaped that they cannot, in existing birds, be applied to the ground for support and be used like the limbs of quadrupeds, and are therefore folded up at the sides of the body, and carried in an unused or useless state so long as the animal hops on the ground or walks, balancing its weight on the hind legs. secondly, there are two small folds of skin, less conspicuous than those on the arms of geckos; one is between the wrist bones and the shoulder, and the smaller hinder membrane is between the upper arm and the body. these membranous expansions are insignificant, and would in themselves be inadequate to support the body or materially assist its movements. thirdly, the bird develops appendages to the skin which are familiarly known as feathers, and the large feathers which make the wing are attached to the skin covering the lower arm bone named the ulna, and the other bones which represent the wrist and hand. the area and form of the bird's wing are due to individual appendages to the skin, which are unknown in any other group of animals. between the extended wing of the albatross, measuring eleven feet in spread, and the condition in the kiwi of new zealand, in which the wing is vanishing, there is every possible variation in size and form. as a rule, the larger the animal the smaller is the wing area. the problem of the origin of the bird's wing is not to be explained by study of existing animals; for the rowing organ of the penguin, which in itself would never suggest flight, becomes an organ of flight in other birds by the growth upon it of suitable feathers. anyone who has seen the birds named divers feeding under water, swimming rapidly with their wings, might never suspect that they were also organs of aerial flight. the ostrich is even more interesting, for it has not developed flight, and still retains at the extremities of two of the digits the slender claws of a limb which was originally no wing at all, but the support of a four-footed animal (fig. , p. ). flying mammals flight is also developed among mammals. the insectivora include several interesting examples of animals which are capable of a certain motion through the air. in the tropical forests of the malay archipelago are animals known as flying squirrels, flying opossums, flying lemurs, flying foxes, in which the skin extends outward laterally from the sides of the body so as to connect the fore limbs with the hind limbs, and is also prolonged backward from the hind limbs to the tail. the four digits are never elongated; the bones of the fore limb are neither longer nor larger than those of the hind limb, and the foot terminates in five little claws as in other four-footed animals. this condition is adapted for the arboreal life which those animals live, leaping from branch to branch, feeding on fruits and leaves, and in some cases upon insects. these mammals may be compared with the flying geckos among reptiles in their parachute-like support by extension of the skin, which gives them one of the conditions of support which contribute to constitute flight. [illustration: fig. . flying squirrel (pteromys)] _bats._--one entire order of mammals--the bats--not only possess true wings, but are capable of flight which is sustained, and in some cases powerful. the wings are clothed with short hair like the rest of the body, and thus the instrument of flight is unlike that of a bird. the flight of a bat differs from that of all other animals in being dependent upon a modification of the bones of the fore limb, which, without interfering with the animal's movements as a quadruped, secures an extension of the wing which is not inferior in area to that which the bird obtains by elongation of the bones of the arm and fore-arm and its feathers. the distinctive peculiarity of the bat's wing is in the circumstance that four of the digits of the hand have their bones prolonged to a length which is often equal to the combined length of the arm and fore-arm. the bones of the digits diverge like the ribs of an umbrella, and between them is the wing membrane, which extends from the sides of the body outward, unites the fore limb with the hind limb, and is prolonged down the tail as in the flying foxes. bats have a small membrane in front of the bones of the arm and fore-arm stretching between the shoulder and the wrist, which corresponds with the wing membrane of a bird; but the remainder of the membranes in bats' wings are absent in birds, because their function is performed by feathers which give the wing its area. the elongated digits of the bat's wing are folded together and carried at the sides of the body as though they were a few quill pens attached to its wrist, where the one digit, which is applied to the ground in walking, terminates in a claw. [illustration: fig. new zealand bat flying. barbastelle walking] the organs which support animals in the air are thus seen to be more or less dissimilar in each of the great groups of animals. they fall into three chief types: first, the parachute; secondly, the wing due to the feathers appended to the skin; and thirdly, the wing formed of membrane, supported by enormous elongation of the small bones of the back of the hand and fingers. the two types of true wings are limited to birds and bats; and no living reptile approximates to developing such an organ of flight as a wing. judged, therefore, by the method of comparing the anatomical structures of one animal with another, which is termed "comparative anatomy," the existence of flying reptiles might be pronounced impossible. but in the light which the revelations of geology afford, our convictions become tempered with modesty; and we learn that with nature nothing is impossible in development of animal structure. chapter v discovery of the pterodactyle late in the eighteenth century, in , a small fossil animal with wings began to be known through the writings of collini, as found in the white lithographic limestone of solenhofen in bavaria, and was regarded by him as a former inhabitant of the sea. the foremost naturalist of the time, the citizen cuvier--for it was in the days of the french republic--in , in lucid language, interpreted the animal as a genus of saurians. that word, so familiar at the present day, was used in the first half of the century to include lizards and crocodiles; and described animals akin to reptiles which were manifestly related neither to serpents nor turtles. but the term saurian is no longer in favour, and has faded from science, and is interesting only in ancient history of progress. the lizards soon became classed in close alliance with snakes. and the crocodiles, with the hatteria, were united with chelonians. most modern naturalists who use the term saurian still make it an equivalent of lizard, or an animal of the lizard kind. cuvier [illustration: fig. . _pterodactylus longirostris_ (cuvier) the remains are preserved with the neck arched over the back, and the jaws opened upward] cuvier defined this fossil from solenhofen as distinguished by the extreme elongation of the fourth digit of the hand, and from that character invented for the animal the name pterodactyle. he tells us that its flight was not due to prolongation of the ribs, as among the living lizards named dragons; or to a wing formed without the digits being distinguishable from each other, as among birds; nor with only one digit free from the wing, as among bats; but by having the wing supported mainly by a single greatly elongated digit, while all the others are short and terminate in claws. cuvier described the amazing animal in detail, part by part; and such has been the influence of his clear words and fame as a great anatomist that nearly every writer in after-years, in french and in english, repeated cuvier's conclusion, maintained to the end, that the animal is a saurian. [illustration: fig. . the skeleton of _pterodactylus longirostris_ reconstructed from the scattered bones in fig. , showing the limbs on the left side] long before fashion determined, as an article of educated belief, that fossil animals exist chiefly to bridge over the gaps between those which still survive, the scientific men of germany were inclined to see in the pterodactyle such an intermediate type of life. at first sömmerring and wagler would have placed the pterodactyle between mammals and birds. goldfuss [illustration: fig. . the _pterodactylus longirostris_ restored from the remains in fig. showing positions of the wing membranes with the animal at rest] but the accomplished naturalist goldfuss, who described another fine skeleton of a pterodactyle in , saw in this flying animal an indication of the course taken by nature in changing the reptilian organisation to that of birds and mammals. it is the first flash of light on a dark problem, and its brilliance of inference has never been equalled. its effects were seen when prince charles bonaparte, the eminent ornithologist, in italy, suggested for the group the name ornithosauria; when the profound anatomist de blainville, in france, placed the short-tailed animal in a class between reptiles and birds named pterodactylia; and andreas wagner, of munich, who had more pterodactyles to judge from than his predecessors, saw in the fossil animal a saurian in transition to a bird. von meyer but the german interpretation is not uniform, and hermann von meyer, the banker-naturalist of frankfurt a./m., who made himself conversant with all that his predecessors knew, and enlarged knowledge of the pterodactyles on the most critical facts of structure, continued to regard them as true reptiles, but flying reptiles. such is the influence of von meyer that all parts of the world have shown a disposition to reflect his opinions, especially as they practically coincide with the earlier teaching of cuvier. owen and huxley in england, cope and marsh in america, gaudry in france, and zittel in germany have all placed the pterodactyles as flying reptiles. their judgment is emphatic. but there is weight of competent opinion to endorse the evolutionary teaching of goldfuss that they rise above reptiles. to form an independent opinion the modern student must examine the animals, weigh their characters bone by bone, familiarise himself, if possible, with some of the rocks in which they are found; to comprehend the conditions under which the fossils are preserved, which have added not a little to the interest in pterodactyles, and to the difficulty of interpretation. geological history of pterodactyles in germany we may briefly recapitulate the geological history. those remains of ornithosaurs which have been mentioned, with a multitude of others which are the glory of the museums of munich, stuttgart, tübingen, heidelberg, bonn, haarlem, and london, have all been found in working the lithographic stone of bavaria. the whitish yellow limestone forms low, flat-topped hills, now isolated from each other by natural denudation, which has removed the intervening rock. the stone is found at some distance north of the danube, in a line due north of augsburg, in the country about pappenheim, and especially at the villages of solenhofen, eichstädt, kelheim, and nusplingen. these beds belong to the rocks which are named white jura limestone in germany, which is of about the same geological age as the kimeridge clay in england. much of it divides into very thin layers, and in these planes of separation the fossils are found. they include the _ammonites lithographicus_ and a multitude of marine shells, king crabs and other crustacea, sea-urchins, and other fossils, showing that the deposit was formed in the sea. the preservation of jelly-fish, which so soon disappear when left dry on the beach, shows that the ancient calcareous mud had unusual power of preserving fossils. into this sea, with its fishes great and small, came land plants from off the land, dragonflies and other insects, tortoises and lizards, pterodactyles with their flying organs, and birds still clothed with feathers. sometimes the wing membranes of the flying reptiles are found fully stretched by the wing finger, as in examples to be seen at munich and in the yale museum in newhaven, in america. at haarlem there is an example in which the wing membrane appears to be folded much as in the wing of a bat, when the animal hangs suspended, with the flying membrane bent into a few wide undulations. the solenhofen slate belongs to about the middle period of the history of flying reptiles, for they range through the secondary epochs of geological time. remains are recorded in germany from the keuper beds at the top of the trias, which is the bottom division of the secondary strata; and i believe i have seen fragments of their bones from the somewhat older muschelkalk of germany. their history in england in england the remains are found for the first time in the lower lias of lyme regis, in dorset, and the upper lias of whitby, in yorkshire. in würtemberg they occur on the same horizons. they reappear in england, in every subsequent age, when the conditions of the strata and their fossils give evidence of near proximity to land. in the stonesfield slate of stonesfield, in oxfordshire, the bones are found isolated, but indicate animals of some size, though not so large as the rare bones of reputed true birds which appear to have left their remains in the same deposit. at least two pterodactyles are found in the oxford clay, known from more or less fragmentary remains or isolated bones; just as they occur in the kimeridge clay, purbeck limestone, wealden sandstones, and especially in newer secondary rocks, named gault, upper greensand, and chalk, in the south-east of england. owing to exceptional facilities for collecting, in consequence of the cambridge greensand being excavated for the valuable mineral phosphate of lime it contains, more than a thousand bones are preserved, more or less broken and battered, in the woodwardian museum of the university of cambridge alone. to give some idea of their abundance, it may be stated that they were mostly gathered during two or three years, as a matter of business, by an intelligent foreman of washers of the nodules of phosphate of lime, which, in commerce, are named coprolites. he soon learned to distinguish pterodactyle bones from other fossils by their texture, and learned the anatomical names of bones from specimens in the university museum. this workman, mr. pond, employed by mr. william farren, brought together not only the best of the remains at cambridge, but most of those in the museums at york and in london, and the thousands of less perfect specimens in public and private collections which passed through the present writer's hands in endeavours to secure for the university useful illustrations of the animal's structure. these fragments, among which there are few entire bones, are valuable, for they have afforded opportunities of examining the articular ends of bones in every aspect, which is not possible when similar organic remains are embedded in rock in their natural connexions. in england flying reptiles disappear with the chalk. in that period they were widely distributed, being found in bohemia, in brazil, and kansas in the united states, as well as in kent and other parts of england. they attained their largest dimensions in this period of geological time. one imperfect fragment of a bone from the laramie rocks of canada was described, i believe, by cope, though not identified by him as ornithosaurian, and is probably newer than other remains. aspect of pterodactyles if this series of animals could all be brought together they would vary greatly in aspect and stature, as well as in structure. some have the head enormously long, in others it is large and deep, characters which are shared by extinct reptiles which do not fly, and to which some birds may approximate; while in a few the head is small and compact, no more conspicuous, relatively, than the head of a sparrow. the neck may be slender like that of a heron, or strong like that of an eagle; the back is always short, and the tail may be inconspicuous, or as long as the back and neck together. these flying reptiles frequently have the proportions of the limbs similar to those of a bat, with fore legs strong and hind legs relatively small; while in some the limbs are as long, proportionately, and graceful as those of a deer. with these differences in proportions of the body are associated great differences in the relative length of the wing and spread of the wing membranes. dimensions of the animals the dimensions of the animals have probably varied in all periods of geological time. the smallest, in the lithographic slate, are smaller than sparrows, while associated with them are others in which the drumstick bone of the leg is eight inches long. in the cambridge greensand and chalk imperfect specimens occur, showing that the upper arm bones are larger than those of an ox. the shaft is one and a half inches in diameter and the ends three inches wide. such remains may indicate pterodactyles not inferior in size to the extinct moas of new zealand, but with immensely larger heads, animals far larger than birds of flight. the late sir richard owen, on first seeing these fragmentary remains, said "the flying reptile with outstretched pinions must have appeared like the soaring roc of arabian romance, but with the features of leathern wings with crooked claws superinduced, and gaping mouth with threatening teeth." eventually we shall obtain more exact ideas of their aspect, when the structures of the several regions of the body have been examined. the great dimensions of the stretch of wing, often computed at twenty feet in the larger examples, might lead to expectations of great weight of body, if it were not known that an albatross, with wings spreading eleven feet, only weighs about seventeen pounds. chapter vi how animals are interpreted by their bones there is only one safe path which the naturalist may follow who would tell the story of the meaning and nature of an extinct type of animal life, and that is to compare it as fully as possible in its several bones, and as a whole, with other animals, especially with those which survive. it is easy to fix the place in nature of living animals and determine their mutual relations to each other, because all the organs--vital as well as locomotive--are available for comparison. on such evidence they are grouped together into the large divisions of beasts, birds, and reptiles; as well as placed in smaller divisions termed orders, which are based upon less important modifications of fundamental structures. all these characteristic organs have usually disappeared in the fossil. hence a new method of study of the hard parts of the skeleton, which alone are preserved, is used in the endeavour to discover how the flying reptile or other extinct animal is to be classified, and how it acquired its characters or came into existence. variations of bones among mammalia [illustration: fig. . the fore limb in four types of mammals comparison of the fore limb in mammals, showing variation of form of the bones with function] resemblances and differences in the bones are easily over-estimated in importance as evidence of pedigree relationship. the mammalia show, by means of such skeletons as are exhibited in any natural history museum, how small is the importance to be attached to even the existence of any group of bones in determining its grade of organisation. the whole whale tribe suckle their young and conform to the distinctive characters in brain and lungs which mark them as being mammals. but if there is one part of the skeleton more than another which distinguishes the mammalia, it is the girdle of bones at the hips which supports the hind limbs. it is characterised by the bone named the ilium being uniformly directed forward. yet in the whale tribe the hip-girdle and the hind limb which it usually supports are so faintly indicated as to be practically lost; while the fore limb becomes a paddle without distinction of digits, and is therefore devoid of hoofs or claws, which are usual terminations of the extremities in mammals. yet this swimming paddle, with its ill-defined bones--sometimes astonishing in number, as well as in fewness of the finger bones--is represented by the burrowing fore limb of the mole, which lives underground; by the elongated hoofed legs of the giraffe, which lives on plains; and the extended arm and finger bones of the bat, which are equally mammals with the whale. from such comparison it is seen that no proportion, or form, or length, or use of the bones of the limbs, or even the presence of limbs, is necessarily characteristic of a mammal. no limitation can be placed upon the possible diversity of form or development of bones in unknown animals, when they are considered in the light of such experience of varied structural conditions in living members of a single class. what is true for the limbs and the bony arches which support them is true for the backbone also, for the ribs, and to some extent for the skull. the neck in the whale is shortened almost beyond recognition. in the giraffe the same seven vertebræ are elongated into a marvellous neck; so that in the technical definition of a mammal both are said to have seven neck vertebræ. yet exceptions show a capacity for variation. one of the sloths reduces the number to six, while another has nine vertebræ in the neck; proving that there is no necessary difference between a mammal and a reptile when judged by a character which is typically so distinctive of mammals as the number of the neck bones. the skull varies too, though to a less extent. the great ant-eater of south america is a mammal absolutely without teeth. the porpoises have a simple unvarying row of conical teeth with single roots extending along the jaw. and the dental armature of the jaws, and relative dimensions of the skull bones, exhibit such diversity, in evidence of what may be parted with or acquired, that recognition of the many reptilian structures and bones in the skull of ornithorhynchus, the australian duckbill, demonstrates that the difficulties in recognising an animal by its bones are real, unless we can discover the animal type to which the bones belong; and that there is very little in osteology which may not be lost without affecting an animal's grade of organisation. variation in skin covering of mammals even the covering of the body varies in the same class, or even order of animals, so that the familiar growth on the skin is never its only possible covering. the indian ant-eater, named manis, which looks like a gigantic fir-cone, the armadillo, which sheathes the body in rings of bone, bearing only a scanty development of hair, are examples of mammalian hair, as singular as the quills of a porcupine, the horn of a rhinoceros, or the growth of hair of varying length and stoutness on different parts of the body in various animals, or the imperfect development of hair in the marine cetacea. among living animals it is enough for practical purposes to say that a mammal is clothed with hair, but in a fossil state the hair must usually be lost beyond recognition from its fineness and shortness of growth. variation in skin covering of birds no class of living animals is more homogeneous than birds; and well-preserved remains prove that, at least as far back in time as the upper oolites, birds were clothed with feathers of essentially the same mode of growth and appearance as the feathers of living birds. there may, therefore, be no ground for assuming that the covering was ever different, though some regions of the skin are free from feathers. yet the variations from fine under-down to the scale-like feathers on the wings of a penguin, or the great feathers in the wings of birds of flight, or the double quill of the ostrich group, are calculated to yield dissimilar impressions in a fossil state, even if the fine down would be preserved in any stratum. variation in the bones of birds osteologically there is less variety in the skeleton of birds than in other great groups of animals. the existing representatives do not exhaust its capability for modification. the few specimens of birds hitherto found in the secondary strata have rudely removed many differences in the bones which separated living birds from reptiles; so that if only the older fossil birds were known, and the tertiary and living birds had not existed, a bird might have been defined as an animal having its jaw armed with teeth, instead of devoid of teeth; with vertebræ cupped at both ends, instead of with a saddle-shaped articulation which in front is concave from side from side, and convex from above downwards; in which the bones of the hand are separate, so that three digits terminating in claws can be applied to the ground, instead of the metacarpal bones being united in a solid mass with clawless digits; and in which the tail is elongated like the tail of a lizard. yet the limits to variation are not to be formulated till nature has exhausted all her resources in efforts to preserve organic types by adapting them to changed circumstances. birds may be regarded theoretically as equally capable with mammals of parting with almost every distinctive structure in the skeleton by which it is best known. even the living frigate bird blends the early joints of the backbone into a compact mass like a sacrum. the penguin has a cup-and-ball articulation in the early dorsal vertebræ, with the ball in front. and the genus cypselus has the upper arm bone almost as broad as long, unlike the bird type. such examples prove that we are apt to accept the predominant structures in an animal type as though they were universal, and forget that inferences based, like those of early investigators, on limited materials may be re-examined with advantage. variation in the bones of reptiles the true reptilia, notwithstanding some strong resemblances to birds in technical characters of the skeleton, display among their surviving representatives an astonishing diversity in the bony framework of the body, exceeding that of the mammalia. this unlooked-for capacity for varying the plan of construction of the skeleton is in harmony with the diversity of structure in groups of extinct animals to which the name reptiles has also been given. the interval in form is so vast between serpent and tortoise, and so considerable in structure of the skeleton between these and the several groups of lizards, crocodiles, and hatteria, that any other diversity could not be more surprising. and the inference is reasonable that just as mammals live in the air, in the sea, on the earth, and burrow under the earth, similar modes of existence might be expected for birds and reptiles, though no bird is yet known to have put on the aspect of a fish, and no reptiles have been discovered which roamed in herds like antelopes, or lived in the air like birds or bats, unless these fossil flying animals prove on examination to justify the name by which they are known. comparative study of structure in this way demolishes the prejudice, born of experience of the life which now remains on earth, that the ideas of reptile and of flight are incongruous, and not to be combined in one animal. the comparative study of the parts of animals does not leave the student in a chaos of possibilities, but teaches us that organic structures, which mark the grades of life, have only a limited scope of change; while nature flings away every part of the skeleton which is not vital, or changes its form with altering circumstances of existence, enforced by revolutions of the earth's surface in geological time, in her efforts to save organisms from extinction and pass the grade of life onward to a later age. the bones are only of value to the naturalist as symbols, inherited or acquired, and vary in value as evidence of the nature and association of those vital organs which differentiate the great groups of the vertebrata. these distinctive structures, which separate mammals, birds, and reptiles, are sometimes demonstrated by the impress of their existence left on the bones; or sometimes they may be inferred from the characters of the skeleton as a whole. chapter vii interpretation of pterodactyles by their soft parts the organs which fix an animal's place in nature we shall endeavour to ascertain what marks of its grade of organisation the pterodactyle has to show. the organs which are capable of modifying the bones are probably limited to the kidneys, the brain, and the organs of respiration. it may be sufficient to examine the latter two. pneumatic foramina in pterodactyles [illustration: fig. . head of the humerus of the pterodactyle ornithocheirus showing position of the pneumatic foramen on the ulnar side of the bone as in a bird] hermann von meyer, the historian of the ornithosaurs of the lithographic slate, as early as described some pterodactyle bones from the lias of franconia, which showed that air was admitted into the interior of the bones by apertures near their extremities, which, from this circumstance, are known as pneumatic foramina. he drew the inference, naturally enough, that such a structure is absolute proof that the pterodactyle was a flying animal. it was not quite the right form in which the conclusion should have been stated, because the ostrich and other birds which do not fly have the principal bones pneumatic. afterwards, in , the larger bones which professor sedgwick, of cambridge, transmitted to sir richard owen established this condition as characteristic of the flying reptiles of the cambridge greensand. it was thus found as a distinctive structure of the bones both at the beginning and the close of the geological history of these animals. von meyer remarks that the supposition readily follows that in the respiratory process there was some similarity between pterodactyles and birds. this cautious statement may perhaps be due to the circumstance that in many animals air cavities are developed in the skull without being connected with organs of respiration. it is well known that the bulk of the elephant's head is due to the brain cavity being protected with an envelope formed of large air cells. small air cells are seen in the skulls of oxen, pigs, and many other mammals, as well as in the human forehead. the head of a bird like the owl owes something of its imposing appearance to the way in which its mass is enlarged by the dense covering of air cells in the bones above the brain, like that seen in some cretaceous pterodactyles. nor are the skulls of crocodiles or tortoises exceptions to the general rule that an animal's head bones may be pneumatic without implying a pneumatic prolongation of air from the lungs. the mere presence of air cells without specification of the region of the skeleton in which they occur is not remarkable. the holes by which air enters the bones are usually much larger in pterodactyles than in birds, but the entrance to the air cell prolonged into the bones is the same in form and position in both groups. so far as can be judged by this character, there is no difference between them. the importance of the comparison can only be appreciated by examining the bones side by side. in the upper arm bone of a bird, on what is known as the ulnar border, near to the shoulder joint, and on the side nearest to it, is the entrance to the air cell in the humerus. in the pterodactyle the corresponding foramen has the same position, form, and size, and is not one large hole, but a reticulation of small perforations, one beyond another, exactly such as are seen in the entrance to the air cell in the bone of a bird, in which the pneumatic character is found. for it is not every bird of flight which has this pneumatic condition of the bones; and dr. crisp stated that quite a number of birds--the swallow, martin, snipe, canary, wood-wren and willow-wren, whinchat, glossy-starling, spotted-fly-catcher, and black-headed bunting--have no air in their bones. and it is well known that in many birds, especially water birds, it is only the upper bones of the limbs which are pneumatic, while the smaller bones retain the marrow. lungs and air cells [illustration: fig. . lungs of the bird apteryx partly opened on the right-hand side the circles are openings of the bronchial tubes on the surface of the lung. the notches on the inner edges of the lungs are impressions of the ribs (after r. owen)] [illustration: fig. . the body of an ostrich laid open to show the air cells which extend through its length (after georges roché)] it may be well to remember that the lungs of a bird are differently conditioned from those of any other animal. instead of hanging freely suspended in the cone-shaped chamber of the thorax formed by the ribs and sternum, they are firmly fixed on each side, so that the ribs deeply indent them and hold them in place. the lungs have the usual internal structure, being made up of branching cells. the chief peculiarity consists in the way in which the air passes not only into them, but through them. the air tube of the throat of a bird, unlike that of a man, has the organ of voice, not at the upper end in the form of a larynx, but at the lower end, forming what is termed a syrinx. there is no evidence of this in a fossil state, although in a few birds the rings of the trachæa become ossified, and are preserved. but below the syrinx the trachæa divides into two bronchi, tubes which carry the ringed character into the lungs for some distance, and these give off branches termed bronchial tubes, the finer subdivisions from which, in their clustered minute branching sacs, make up the substance of the lung. there is nothing exceptional in that. but towards the outer or middle part of the ventral or under surface of the lungs, four or five rounded openings are seen on each side. each of these openings resembles the entrance of the air cell into a bone, since it displays several smaller openings which lead to it. each opening from the lung leads to an air cell. those cells may be regarded as the blowing out of the membrane which covers the lungs into a film which holds air like a mass of soap bubbles, until the whole cavity of the body of a bird from neck to tail is occupied by sacculated air cells, commonly ten in number, five on each side, though two frequently blend at the base of the neck in the region of the #v#-shaped bone named the clavicle or furculum, popularly known as the merry-thought. most people have seen some at least of these semi-transparent bladder-like air cells beneath the skin in the abdominal region of a fowl. the cells have names from their positions, and on each side one is abdominal, two are thoracic, one clavicular, and one cervical, which last is at the base of the neck. the clavicular and abdominal air cells are perhaps the most interesting. the air cell termed clavicular sends a process outward towards the arm, along with the blood vessels which supply the arm. thus this air cell, entering the region of the axilla or arm-pit, enters the upper arm bone usually on its under side, close to the articular head of the humerus, and in the same way the air may pass from bone to bone through every bone in the fore limb. the hind limbs similarly receive air from the abdominal air cell, which supplies the femur and other bones of the leg, the sacrum, and the tail. but the joints of the backbone in front of the sacrum receive their air from the cervical air sac. the air cells are not limited to the bones, but ramify through the body, and in some cases extend among the muscles. a bird may be said to breathe not only with its lungs, but with its whole body. and it is even affirmed that respiration has been carried on through a broken arm bone when the throat was closed, and the bird under water. birds differ greatly in the extent to which the aircell system prolonged from the lungs is developed, some having the air absent from every bone, while others, like the swift, are reputed to have air in every bone of the body. comparison shows that in so far as the bones are the same in bird and ornithosaur, the evidence of the air cells entering them extends to resemblance, if not coincidence, in every detail. no living group of animals except birds has pneumatic limb bones, in relation to the lungs; so that it is reasonable to conclude that the identical structures in the bones were due to the same cause in both the living and extinct groups of animals. it is impossible to say that the lungs were identical in birds and pterodactyles, but so far as evidence goes, there is no ground for supposing them to have been different. the lungs of reptiles [illustration: fig. . the side of the body of a chameleon ribs removed to show the sacculate branched form of the lung] there is nothing comparable to birds, either in the lungs of living reptiles or in their relation to the bones. the chameleon is remarkable in that the lung is not a simple bladder prolonged through the whole length of the body cavity, as in a serpent, but it develops a number of large lateral branches visible when the body is laid open. except near the trachæa, where the tissue has the usual density of a lizard lung, the air cell is scarcely more complicated than the air bladder of a fish, and does not enter into any bone of the skeleton. and although many fishes like the loach have the swim bladder surrounded by bone connected with the head, it offers no analogy to the pneumatic condition of the bones in the pterodactyle. the form of the brain cavity [illustration: fig. . the form of the brain] but the identity of the pneumatic foramina in birds and flying reptiles is not a character which stands by itself as evidence of organisation, for a mould of the form of the brain case contributes evidence of another structural condition which throws some light on the nature of ornithosaurs. among many of the lower animals, such as turtles, the brain does not fill the chamber in the dry skull, in which the same bones are found as are moulded upon the brain in higher animals. for the brain case in such reptiles is commonly an envelope of cartilage, as among certain fishes; and except among serpents, the ophidia, the bones do not completely close the reptilian brain case in front. the brain fills the brain case completely among birds. a mould from its interior is almost as definite in displaying the several parts of which it is formed as the actual brain would be. and the chief regions of the brain in a bird--cerebrum, optic lobes, cerebellum--show singularly little variation in proportion or position. the essential fact in a bird's brain, which separates it absolutely from all other animals, is that the pair of nerve masses known as the optic lobes are thrust out at the sides, so that the large cerebral hemispheres extend partly over them as they extend between them to abut against the cerebellum. this remarkable condition has no parallel among other vertebrate animals. in fishes, amphibians, reptiles, and mammals the linear succession of the several parts of the brain is never departed from; and any appearance of variation from it among mammals is more apparent than real, for the linear succession may be seen in the young calf till the cerebral hemispheres grow upward and lop backward, so as to hide the relatively small brain masses which correspond to the optic lobes of reptiles, extending over these corpora-quadrigemina, as they are named, so as to cover more or less of the mass of the cerebellum. from these conditions of the brain and skull, it would not be possible to mistake a mould from the brain case of a bird for that of a reptile, though in some conditions of preservation it is conceivable that the mould of the brain of a bird might be distinguished with difficulty from that of the brain in the lowest mammals. taken by itself, the avian form of brain in an animal would be as good evidence that its grade of organisation was that of a bird as could be offered. the brain in solenhofen pterodactyles it happens that moulds of the brain of pterodactyles, more or less complete, are met with of all geological ages--liassic, oolitic, and cretaceous. the solenhofen slate is the only deposit in europe in which pterodactyle skulls can be said to be fairly numerous. they commonly have the bones so thin as to show the form of the upper surface of the mould of the brain, or the bones have scaled off the mould, or remain in the counterpart slab of stone, so as to lay bare the shape of the brain mass. in the museum at heidelberg a skull of this kind is seen in the long-tailed genus of pterodactyles named rhamphorhynchus. it shows the large rounded cerebral hemispheres, which extend in front of cerebral masses of smaller size a little below them in position, which perhaps are as like the brain of a monotreme mammal as a bird. the short-tailed pterodactylus described by cuvier has the cerebral hemispheres very similar to those of a bird, but the relations of the hinder parts of the brain to each other are less clear. the first specimen to show the back of the brain was found by mr. john francis walker, m.a., in the cambridge greensand. i was able to remove the thick covering of cellular bone which originally extended above it, and thus expose evidence that in the mutual relations of the fore and hind parts of the brain bird and ornithosaur were practically identical. another cambridge greensand skull showed that in the genus ornithocheirus the optic lobes of the brain are developed laterally, as in birds. that skull was isolated and imperfect. but about the same time the late rev. w. fox, of brixton, in the isle of wight, obtained from wealden beds another skull, with jaws, teeth, and the principal bones of the skeleton, which showed that the wealden pterodactyle ornithodesmus had a similar and bird-like brain. in mr. e. t. newton, f.r.s., obtained a skull from the upper lias, uncrushed and free from distortion. this made known the natural mould of the brain, which shows the cerebral hemispheres, optic lobes, and cerebellum more distinctly than in the specimens previously known. in some respects it recalls the heidelberg brain of rhamphorhynchus in the apparently transverse subdivision of the optic lobes, but it is unmistakably bird-like, and quite unlike any reptile. importance of the brain and breathing organs so far as the evidence goes, it appears that these fossil flying animals show no substantial differences from birds, either in the mould of the brain or the impress of the breathing organs upon the bones. these approximations to birds of the nervous and respiratory systems, which are beyond question two of the most important of the vital organs of an animal, and distinctive beyond all others of birds, place the naturalist in a singular dilemma. he must elect whether he will trust his interpretation to the soft organs, which among existing animals never vary their type in the great classes of vertebrate animals, and on which the animal is defined as something distinct from its envelope the skeleton and its appendages the limbs, or whether he will ignore them. the answer must choose substantially between belief that the existing order of nature gives warrant for believing that these vital characteristics which have been discussed might equally coexist with the skeleton of a mammal or a reptile, as with that of a bird, for which there is no particle of evidence in existing life. or, as an alternative, the fact must be accepted that birds only have such vital organs as are here found, and therefore the skeleton, that may be associated with them, cannot affect the reference of the type to the same division of the animal kingdom as birds. the decision need not be made without further consideration. but brain and breathing organs of the avian type are structures of a different order of stability in most animals from the bones, which vary to a remarkable extent in almost every ordinal group of animals. temperature of the blood the organs of circulation and digestion are necessarily unknown. there are reasons why the blood may have been hot, such as the evidences from the wings of exceptional activity; though the temperature depends more upon the amount of blood in the body than upon the apparatus by which it is distributed. we speak of a crocodile as cold-blooded, yet it is an animal with a four-chambered heart not incomparable with that of a bird. on the other hand, the tunny, a sort of giant mackerel, is a fish with a three-chambered heart, only breathing the air dissolved in water, which has blood as warm as a mammal, its temperature being compared to that of a pig. several fishes have blood as warm as that of manis, the scaly ant-eater; and many birds have hotter blood than mammals. the term "hot-blooded," as distinct from "cold-blooded," applied to animals, is relative to the arbitrary human standard of experience, and expresses no more than the circumstance that mammals and birds are warmer animals than reptiles and fishes. the exceptional temperature of the flying fish has led to a vague impression that physical activity and its effect upon the amount of blood which vigour of movement circulates, are more important in raising an animal's temperature than possession of the circulatory organs commonly associated with hot blood, which drive the blood in distinct courses through the body and breathing organs. yet the kind of heart which is always associated with vital structures such as pterodactyles are inferred to have possessed from the brain mould and the pneumatic foramina in the bones, is the four-chambered heart of the bird and the mammal. considering these organs alone--of which the fossil bones yield evidence--we might anticipate, by the law of known association of structures, that nothing distinctly reptilian existed in the other soft part of the vital organisation, because there is no evidence in favour of or against such a possibility. chapter viii the plan of the skeleton while these animals are incontestably nearer to birds than to any other animals in their plan of organisation, thus far no proof has been found that they are birds, or can be included in the same division of vertebrate life with feathered animals. it is one of the oldest and soundest teachings of linnæus that a bird is known by its feathers; and the record is a blank as to any covering to the skin in pterodactyles. there is the strongest probability against feathers having existed such as are known in the archæopteryx, because every solenhofen ornithosaur appears to have the body devoid of visible or preservable covering, while the two birds known from the solenhofen slate deposit are well clothed with feathers in perfect preservation. we turn from the skin to the skeleton. the plan on which the skeleton is constructed remains as evidence of the animal's place in nature, which is capable of affording demonstration on which absolute reliance would have been placed, if the brain and pneumatic foramina had remained undiscovered. with the entire skeleton before us, it is inconceivable that anatomical science should fail to discover the true nature of the animal to which it belonged, by the method of comparing one animal with another. there is no lack of this kind of evidence of pterodactyles in the three or four scores of skeletons, and thousands of isolated or associated bones, preserved in the public museums of europe and america. i may recall the circumstance that the discovery of skeletons of fossil animals has occasionally followed upon the interpretation of a single fragment, from which the animal has been well defined, and sometimes accurately drawn, before it was ever seen. so i propose, before drawing any conclusions from the skeletons in the entirety of their construction, to examine them bone by bone, and region by region, for evidence that will manifest the nature of this brood of dragons. their living kindred, and perhaps their extinct allies, assembled as a jury, may be able to determine whether resemblances exist between them, and whether such similarity between the bones as exists is a common inheritance, or is a common acquisition due to similar ways of life, and no evidence of the grade of the organism among vertebrate animals. the bones of these ornithosaurs, when found isolated, first have to be separated from the organisms with which they are associated and mixed in the geological strata. this discrimination is accomplished in the first instance by means of the texture of the surface. the density and polish of the bones is even more marked than in the bones of birds, and is usually associated with a peculiar thinness of substance of the bone, which is comparable to the condition in a bird, though usually a little stouter, so that the bones resist crushing better. pterodactyle bones in many instances are recognised by their straightness and comparatively uniform dimensions, due to the exceptional number of long bones which enter into the structure of the wing as compared with birds. when the bones are unerringly determined as ornithosaurian, they are placed side by side with all the bones which are most like them, till, judged by the standard of the structures of living animals, the fossil is found to show a composite construction as though it were not one animal but many, while its individual bones often show equally composite characters, as though parts of the corresponding bone in several animals had been cunningly fitted together and moulded into shape. the plan of the head in ornithosaurs the head is always the most instructive part of an animal. it is less than an inch long in the small solenhofen skeleton named _pterodactylus brevirostris_, and is said to be three feet nine inches long in the toothless pterodactyle ornithostoma from the chalk of kansas. most of these animals have a long, slender, conical form of head, tapering to the point like the beak of a heron, forming a long triangle when seen from above or from the side. sometimes the head is depressed in front, with the beak flattened or rounded as in a duck or goose, and occasionally in some wealden and greensand species the jaws are truncated in front in a massive snout quite unlike any bird. the back of the head is sometimes rounded as among birds, showing a smooth pear-shaped posterior convexity in the region of the brain. sometimes the back of the head is square and vertical or oblique. occasionally a great crest of cellular tissue is extended backward from above the brain case over the spines of the neck bones. there are always from two to four lateral openings in the skull. first, the nostril is nearest to the extremity of the beak. secondly, the orbits of the eyes are placed far backward. these two openings are always present. the nostril may incline upward. the orbits of the eyes are usually lateral, though their upper borders sometimes closely approximate, as in the woodpecker-like types from the solenhofen slate named _pterodactylus kochi_, now separated as another genus. in most genera there is an opening in the side of the head, between the eye hole and the nostril, known as the antorbital vacuity; and another opening, which is variable in size and known as the temporal vacuity, is placed behind the eye. the former is common in the skulls of birds, the latter is absent from all birds and found in many reptiles. the palate is usually imperfectly seen, but english and american specimens have shown that it has much in common with the palate in birds, though it varies greatly in form of the bones in representatives from the lias, oolites, and cretaceous rocks. from the scientific aspect the relative size of the head, its form, and the positions and dimensions of its apertures and processes, are of little importance in comparison with its plan of construction, as evidenced by the positions and relations to each other of the bones of which it is formed. there usually is some difficulty in stating the limits of the bones of the skull, because in pterodactyles, as among birds, they usually blend together, so that in the adult animal the sutures between the bones are commonly obliterated. bones have relations to each other and places in the head which can only change as the organs with which they are associated change their positions. no matter what the position of a nostril may be--at the extremity of a long snout, as in an ant-eater, or far back at the top of the head in a porpoise, or at the side of the head in a bird--it is always bordered by substantially the same bones, which vary in length and size with the changing place of the nostril and the form of the head. every region of the head is defined by this method of construction; so that eye holes and nose holes, brain case and jaw bones, palate and teeth, beak, and back of the skull are all instructive to those who seek out the life-history of these animals. we may briefly examine the head of an ornithosaurian. bones about the nostril no matter what its form may be, the head of an ornithosaur always terminates in front in a single bone called the intermaxillary. it sends a bar of bone backward above the visible nostrils, between them; and a bar on each side forms the margin of the jaw in which teeth are implanted. the bone varies in depth, length, sharpness, bluntness, slenderness, and massiveness. as the bone becomes long the jaw is compressed from side to side, and the openings of the nostrils are removed backward to an increasing distance from the extremity of the beak. the outer and hinder border of the nostril is made by another bone named the maxillary bone, which is usually much shorter than the premaxillary. it contains the hindermost teeth, which rarely differ from those in front, except in sometimes being smaller. the nasal bones, which always make the upper and hinder border of the nostrils, meet each other above them, in the middle line of the beak. [illustration: fig. showing that the extremity of the jaws in rhamphorhynchus was sheathed in horn as in the giant kingfisher, since the jaws similarly gape in front. the hyoid bones are below the lower jaw in the pterodactyle.] the nostrils are unusually large in the lias genus named dimorphodon, and small in species of the genus rhamphorhynchus from solenhofen. such differences result from the relative dimensions and proportions of these three bones which margin the nasal vacuity, and by varying growth of their front margins or of their hinder margins govern the form of the snout. the jaws are most massive in the genera known from the wealden beds to the chalk. the palatal surface is commonly flat or convex, and often marked by an elevated median ridge which corresponds to a groove in the lower jaw, though the median ridge sometimes divides the palate into two parallel concave channels. the jaw is margined with teeth which are rarely fewer than ten or more than twenty on each side. they are sharp, compressed from side to side, curved inward, and never have a saw-like edge on the back and front margins. no teeth occur upon the bones of the palate. in most birds there is a large vacuity in the side of the head between the nostril and the orbit of the eye, partly separated from it by the bone which carries the duct for tears named the lachrymal bone. the same preorbital vacuity is present in all long-tailed pterodactyles, though it is either less completely defined or absent in the group with short tails. it affords excellent distinctive characters for defining the genera. in the long-tailed genus scaphognathus from solenhofen this preorbital opening is much larger than the nostril, while in dimorphodon these vacuities are of about equal size. rhamphorhynchus is distinguished by the small size of the antorbital vacuity, which is placed lower than the nostril on the side of the face. the aperture is always imperfectly defined in pterodactylus, and is a relatively small vacuity compared with the long nostril. in ptenodracon the antorbital vacuity appears to have no existence separate from the nostril which adjoins the eye hole. and so far as is known at present there is no lateral opening in advance of the eye in the skull in any ornithosaur from cretaceous rocks, though the toothless ornithostoma is the only genus with the skull complete. when a separate antorbital vacuity exists, it is bordered by the maxillary bone in front, and by the malar bone behind. the prefrontal bone is at its upper angle. that bone is known in a separate state in reptiles and, i think, in monotreme mammals. its identity is soon lost in the mammal, and its function in the skull is different from the corresponding bone in pterodactyles. bones about the eyes [illustration: fig. . upper surface of skull of the heron compared with the same aspect of the skull of rhamphorhynchus] the third opening in the side of the head, counting from before backward, is the orbit of the eye. in this vacuity is often seen the sclerotic circle of overlapping bones formed in the external membrane of the eye, like those in nocturnal birds and some reptiles. the eye hole varies in form from an inverted pear-shape to an oblique or transverse oval, or a nearly circular outline. it is margined by the frontal bone above; the tear bone or lachrymal, and the malar or cheek bone in front; while the bones behind appear to be the quadrato-jugal and post-frontal bones, though the bones about the eye are somewhat differently arranged in different genera. the eyes were frequently, if not always, in contact with the anterior walls of the brain case, as in many birds, and are always far back in the side of the head. in dimorphodon they are in front of the articulation of the lower jaw; in rhamphorhynchus, above that articulation; while in ornithostoma they are behind the articulation for the jaw. this change is governed by the position of the quadrate bone, which is vertical in the lias genus, inclined obliquely forward in the fossils from the oolites, and so much inclined in the chalk fossil that the small orbit is thrown relatively further back. thus far the chief difference in the pterodactyle skull from that of a bird is in the way in which the malar arch is prolonged backward on each side. it is a slender bar of bone in birds, without contributing ascending processes to border vacuities in the side of the face, while in these fossil animals the lateral openings are partly separated by the ascending processes of these bones. this divergence from birds, in the malar bone entering the orbit of the eye is approximated to among reptiles and mammals, though the conditions, and perhaps the presence of a bone like the post-orbital bone, are paralleled only among reptiles. the pterodactyles differ among themselves enough for the head to make a near approach to reptiles in dimorphodon, and to birds in pterodactylus. in the ground hornbill and the shoebill the lachrymal bones in front of the orbits of the eyes grow down to meet the malar bars without uniting with them. the post-frontal region also is prolonged downward almost as far as the malar bar, as though to show that a bird might have its orbital circle formed in the same way and by the same bones as in pterodactylus. cretaceous ornithosaurs sometimes differ from birds apparently in admitting the quadrato-jugal bone into the orbit. it then becomes an expanded plate, instead of a slender bar as in all birds. the temporal fossa a fourth vacuity is known as the temporal fossa. when the skull of such a mammal as a rabbit, or sheep, is seen from above, there is a vacuity behind the orbits for the eyes, which in life is occupied by the muscles which work the lower jaw. it is made by the malar bone extending from the back of the orbit and the process of bone, called the zygomatic process, extending forward from the articulation of the jaw, which arches out to meet the malar bone. in birds there is no conspicuous temporal fossa, because the malar bar is a slender rod of bone in a line with the lower end of the quadrate bone. reptile skulls have sometimes one temporal vacuity on each side, as among tortoises, formed by a single lateral bar. these vacuities, which correspond to those of mammals in position, are seen from the top of the head, as lateral vacuities behind the orbits of the eyes, and are termed superior temporal vacuities. in addition to these there is often in other reptiles a lateral opening behind the eye, termed the inferior temporal vacuity, seen in crocodiles, in hatteria, and in lizards; and in such skulls there are two temporal bars seen in side view, distinguished as superior and inferior. the superior arch always includes the squamosal bone, which is at the back of the single bar in mammals. the lower arch includes the malar bone, which is in front in the single arch of mammals. the circumstance that both these arches are connected with the quadrate bone makes the double temporal arch eminently reptilian. in ornithosaurs the lateral temporal vacuity varies from a typically reptilian condition to one which, without becoming avian, approaches the bird type. in skulls from the lias, dimorphodon and campylognathus, there is a close parallel to the living new zealand reptile hatteria, in the vertical position of the quadrate bone and in the large size of the vacuity behind and below the eye, which extends nearly the height of the skull. in the species of the genus pterodactylus, the forward inclination of the quadrate bone recalls the curlew, snipe, and other birds. the back of the head is rounded, and the squamosal bone, which appears to enter into the wall of the brain case as in birds and mammals, is produced more outward than in birds, but less than in mammals, so as to contribute a little to the arch which is in the position of the post-frontal bone of reptiles. it is triangular, and stretches from the outer angle of the frontal bone at the back of the orbit to the squamosal behind, where it also meets the quadrate bone. its third lower branch meets the quadratojugal, which rests upon the front of the quadrate bone, as in iguanodon, and is unlike dimorphodon in its connexions. in that genus the supra-temporal bone, or post-orbital bone, appears to rest upon the post-frontal and connect it with the quadrato-jugal. in dimorphodon the malar bone is entirely removed from the quadrate, but in pterodactylus it meets its articular end. between the post-frontal bone above and the quadrato-jugal bone below is a small lunate opening, which represents the lateral temporal vacuity; and so far, this is a reptilian character. but if the thin post-frontal bone were absorbed, pterodactylus would resemble birds. there is no evidence that the quadrate bone is free in any ornithosaurs, as it is in all birds, while in dimorphodon it unites by suture with the squamosal bone. in ornithostoma the lateral temporal vacuity is little more than a slit between the quadrate bone below, the quadrato-jugal in front, and what may be the post-frontal bone behind (see fig. , p. ). bones about the brain the bones containing the brain appear to be the same as form the brain case in birds. the form of the back of the skull varies in two ways. first it may be flat above and flat at the back, when the back of the head appears to be square. this condition is seen in all the long-tailed genera, such as campylognathus from the lias and rhamphorhynchus, and is associated with a high position for the upper temporal bar. secondly, the back of the head may be rounded convexly, both above and behind. that condition is seen in the short-tailed genera, such as pterodactylus. but in the large cretaceous types, such as ornithocheirus and ornithostoma, the superior longitudinal ridge which runs back in the middle line of the face becomes elevated and compressed from side to side at the back of the head as a narrow deep crest, prolonged backward over the neck vertebræ for some inches of length. all these three types are paralleled more or less in birds which have the back of the head square like the heron, or rounded like the woodpecker; or crested, though the crest of the cormorant is not quite identical with ornithocheirus, being a distinct bone at the back of the head in the bird which never blends with the skull. in so far as the crest is reptilian it suggests the remarkable crest of the chameleon. in the structure of the back of the skull the bones are a modification of the reptilian type of hatteria in the lias genus campylognathus, but the reptilian characters appear to be lost in the less perfectly preserved skulls of cretaceous genera. the palate is well known in the chief groups of ornithosaurs, such as campylognathus, scaphognathus, and cycnorhamphus. mr. e. t. newton, f.r.s., has shown that in the english skull from the lias of whitby, the forms of the bones are similar to the palate in birds and unlike the conditions in reptiles. there is one feature, however, which may indicate a resemblance to dicynodon and other fossil reptiles from south africa. a slender bone extends from the base of the brain case, named the basi-sphenoid bone, outward and forward to the inner margin of the quadrate bone (fig. ). a bone is found thus placed in those south african reptiles, which show many resemblances to the monotreme and marsupial mammals. it is not an ordinary element of the skeleton and is unknown in living animals of any kind in that position. it has been thought possible that it may represent one of the bones which among mammals are diminutive and are included in the internal ear. the resemblance may have some interest hereafter, as helping to show that certain affinities of the ornithosaurs may lie outside the groups of existing reptiles. instead of being directed transversely outward, as in the palatal region of _dicynodon lacerticeps_, they diverge outward and forward to the inner border of the articulation for the lower jaw which is upon the quadrate bone. [illustration: fig. ] bones of the palate there is a pair of bones which extend forward from these inner articular borders of the quadrate bones, and converge in a long #v#-shape till they merge in the hard palate formed by the bones of the front of the beak, named intermaxillary and maxillary bones. the limits of the bones of the palate are not distinct, but there can be no doubt that the front of the #v# is the bone named vomer, that the palatine bones are at its sides, and that its hinder parts are the pterygoid bones as in birds. there is a long, wide, four-sided, open space in the middle of the palate, between the vomer and the basi-sphenoid bone, unlike anything in birds or other animals. professor marsh, in a figure of the palate in the great skull of the toothless pterodactyle named ornithostoma (pteranodon), from the chalk of kansas, found a large oval vacuity in this region of the palate. in that genus the pterygoid bones meet each other between the quadrate bones as in dicynodon (fig. , p. ). hence the great palatal vacuity here seen in the ornithosaur is paralleled by the small vacuity in the south african reptile, which is sometimes distinct and sometimes partly separated from the anterior part of the vacuity which forms the openings of the nostrils on the palate. the solenhofen skulls which give any evidence of the palate are exposed in side view only, and the bones, imperfectly seen through the lateral vacuities, are displaced by crushing. they include long strips like the vomerine bones in the lias fossil, and they diverge in the same way as they extend back to the quadrate bones. the oblique division into vomer in front and pterygoid bone behind is shown by goldfuss in his original figure of scaphognathus. thus there is some reason for believing that all ornithosaurs have the palate formed upon the same general plan, which is on the whole peculiar to the group, especially in not having the palatal openings of the nares divided in the middle line. it would appear probable that the short-tailed animals have the pterygoid bones meeting in the middle line and triangular; and that they are slender rods entirely separate from each other in the long-tailed genera. the teeth the teeth are all of pointed, elongated shape, without distinction into the kinds seen in most mammals and named incisors, canines, and grinders. they are organs for grasping, like the teeth of the fish-eating crocodile of india, and are not unlike the simple teeth of some porpoises. they are often implanted in oblique oval sockets with raised borders, usually at some distance apart from each other, and have the crown pointed, flattened more on the outer side than on the inner side, usually directed forward and curved inward. as in many extinct animals allied to existing reptiles, the teeth are reproduced by germs, which originate on the inner side of the root and grow till they gradually absorb the substance of the old tooth, forming a new one in its place. frequently in solenhofen genera, like scaphognathus and pterodactylus, the successional tooth is seen in the jaw on the hinder border of the tooth in use. there is some variation in the character of bluntness or sharpness of the crowns in the different genera, and in their size. the name dimorphodon, given to the animal from the lias of lyme regis, expresses the fact that the teeth are of two kinds. in the front of the jaw three or four large long teeth are found in the intermaxillary bone on each side, as in some plesiosaurs, while the teeth found further back in the maxillary bone are smaller, and directed more vertically downward. this difference is more marked in the lower jaw than in the upper jaw. in rhamphorhynchus the teeth are all relatively long and large, and directed obliquely forward, but absent from the extremities of the beak, as in the german genus from the lias named dorygnathus, in which the bone of the lower jaw (which alone is known) terminates in a compressed spear. in scaphognathus the teeth are few, more vertical, and do not extend backward so far as in rhamphorhynchus, but are carried forward to the extremity of the blunt, deep jaw. in the short-tailed pterodactyles the teeth are smaller, shorter, wider at the base of the crown, closer together, and do not extend so far backward in the jaw. in ornithocheirus two teeth always project forward from the front of the jaw. ornithostoma is toothless. supposed horny beak sometimes a horny covering has been suggested for the beak, like that seen in birds or turtles, but no such structure has been preserved, even in the solenhofen slate, in which such a structure would seem as likely to be preserved as a wing membrane, though there is one doubtful exception. there are marks of fine blood vessels on some of the jaws, indicating a tough covering to the bone. in rhamphorhynchus the jaws appear to gape towards their extremities as though the interspace had originally been occupied by organic substance like a horny beak. lower jaw the lower jaw varies in relative length with the vertical or horizontal position of the quadrate bone in the skull. in dimorphodon the jaw is as long as the skull; but in the genera from the oolitic rocks the mandible is somewhat shorter, and in ornithostoma the discrepancy reaches its maximum. the hinder part of the jaw is never prolonged backward much beyond the articulation, differing in this respect from crocodiles and plesiosaurs. the depth of the jaw varies. it is slender in pterodactylus, and is probably stronger relatively to the skull in scaphognathus than in any other form. it fits between the teeth and bones of the alveolar border in the skull, in all the genera. in dimorphodon its hinder border is partly covered by the descending edge of the malar process which these animals develop in common with some dinosaurs, and some anomodont reptiles, and many of the lower mammals. in this hinder region the lower jaw is sometimes perforated, in the same way as in crocodiles. that condition is observed in dimorphodon, but is not found in pterodactylus. the lower jaw is always composite, being formed by several bones, as among reptiles and birds. the teeth are in the dentary bone or bones, and these bones are almost always blended as in most birds and turtles, and not separate from each other as among crocodiles, lizards, and serpents. an interesting contour for the lower border of the jaw is seen in ornithostoma, as made known in figures of american examples by professors marsh and williston. it deepens as it extends backwards for two-thirds its length, stops at an angle, and then the depth diminishes to the articulation with the skull. this angle of the lower jaw is a characteristic feature of the jaws of mammals. it is seen in the monotreme echidna, and is characteristic of some theriodont reptiles from south africa, which in many ways resemble mammals. the character is not seen in the jaws of specimens from the oolitic rocks, but is developed in the toothed ornithocheirus from the cambridge greensand, and is absent from the jaws of existing reptiles and birds. [illustration: fig. comparison of the lower jaw in echidna and ornithostoma] summary of characters of the head taken as a whole, the head differs from other types of animals in a blending of characters which at the present day are found among birds and reptiles, with some structures which occur in extinct groups of animals with similar affinities, and perhaps a slight indication of features common to the lowest mammals. it is chiefly upon the head that the diverse views of earlier writers have been based. cuvier was impressed with the reptilian aspect of the teeth; but in later times discoveries were made of birds with teeth--archæopteryx, ichthyornis, hesperornis. the teeth are quite reptilian, being not unlike miniature teeth of mosasaurus. if those birds had been found prior to the discovery of pterodactyles, the teeth might have been regarded as a link with the more ancient birds, rather than a crucial difference between birds and reptiles. all the specimens show a lateral temporal hole in the bones behind the eye, and this is found in no bird or mammal, and is typical of such reptiles as hatteria. the quadrate bone may not be so decisive as cuvier thought it to be, for its form is not unlike the quadrate of a bird, and different, so far as i have seen, from that of living reptiles. this region of the head is reptilian, and if it occurred in a bird the character would be as astonishing as was the discovery of teeth in extinct birds. these characters of the head are also found in fossil animals named dinosaurs, in association with many resemblances to birds in their bones. the palate might conceivably be derived from that of hatteria by enlarging the small opening in the middle line in that reptile till it extended forward between the vomera; but it is more easily compared with a bird, which the animal resembles in its beak, and in the position of the nares. excepting certain lizards, all true existing reptiles have the nostrils far forward and bordered by two premaxillary bones instead of one intermaxillary, as in birds and ornithosaurs. if nothing were known of the animal but its head bones, it would be placed between reptiles and birds. chapter ix the backbone, or vertebral column the backbone is a more deep-seated part of the skeleton than the head. it is more protected by its position, and has less varied functions to perform. therefore it varies less in distinctive character within the limits of each of the classes of vertebrate animals than either the head or limbs. it is divided into neck bones, the cervical vertebræ; back bones, the dorsal vertebræ; loin bones, the lumbar vertebræ; the sacrum, or sacral vertebræ, which support the hind limbs; and the tail. of these parts the tail is the least important, though it reaches a length in existing reptiles which sometimes exceeds the whole of the remainder of the body, and includes hundreds of vertebræ. it attains its maximum among serpents and lizards. in frogs it is practically absent. in some of the higher mammals it is a rudiment, which does not extend beyond the soft parts of the body. the neck the neck is more liable to vary than the back, with the habit of life of the animal. and although mammals almost always preserve the same number of seven bones in the neck, the bones vary in length between the short condition of the porpoise, in which the neck is almost lost, and the long bones which form the neck of the llama, though even these may be exceeded by some fossil reptiles like tanystrophoeus. in many mammals the neck bones do not differ in length or size from those of the back. in others, like the horse and ox, they are much broader and larger. there is the same sort of variation in the bones of the neck among birds, some being slender like the heron, others broad like the swan. but there is also a singular variation in number of vertebral bones in a bird's neck. at fewest there are nine, which equals the exceptionally large number found among mammals in the neck of one of the sloths. usually birds have ten to fifteen cervical vertebræ, and in the swan there are twenty-three. most of the neck bones of birds are relatively long, and the length of the neck is often greater than the remainder of the vertebral column. reptiles usually have short necks. the common turtle has eight bones in the neck, ten in the back. the two regions are sharply defined by the dorsal shield. their articular ends are sometimes cupped in front, in the neck, sometimes cupped behind, or convex at both ends, or even flattened, or the articulation may be made exceptionally by the neural arch alone. nine is the largest number of neck bones in existing lizards, and there are usually nine in crocodiles; so that reptiles closely approach mammals in number of the neck bones. it is remarkable that the maximum number in a mammal and in living reptiles should coincide with the minimum number in birds. therefore the number of cervical vertebræ as an attribute of mammal, bird, or reptile, can only be important from its constancy. german naturalists affirm on clear evidence that the solenhofen pterodactyles have seven cervical vertebræ. in many specimens there can be no doubt about the number, because the neck bones are easily distinguished from those of the back by their size; but the number is not always easy to count. as in birds, the first vertebra, or atlas, in pterodactyles is extremely short, and is generally--if not always--blended with the much longer second vertebra, named the axis. the front of the atlas forms a small rounded cup to articulate with the rounded ball of the basioccipital bone at the back of the skull. the third and fourth vertebræ are longer, but the length visibly shortens in the sixth and seventh. sometimes the vertebræ are slender and devoid of strong spinous processes. this is the condition in the little _pterodactylus longirostris_ and in the comparatively large _cycnorhamphus fraasii_, in which there is a slight median ridge along the upper surface of the arch of the vertebra. this condition is paralleled in birds with long necks, especially wading birds such as the heron. other ornithosaurs, such as ornithocheirus from the cretaceous rocks, have the neck much more massive. the vertebræ are flattened on the under side. the arch above the nervous matter of the spinal cord has a more or less considerable transverse expansion, and may even be as wide as long. these vertebræ have proportions and form such as may be seen in vultures or in the swan. in either case the form of the neck bones is more or less bird-like, and the neural spine may be elevated, especially in pterodactyles with long tails. one of the most distinctive features of the neck bones of a bird is the way in which the cervical ribs are blended with the vertebræ. they are small, and each is often prolonged in a needle-like rod at the side of the neck bone. in ornithocheirus the cervical rib similarly blends with the vertebra by two articulations, as in mammals, so that it might escape notice but for the channel of a blood vessel which is thus inclosed. in several of the older pterodactyles from solenhofen the ribs of the neck vertebræ remain separated, as in a crocodile, though still bird-like in their form, anterior position, and mode of attachment. in terrapins and tortoises the long neck vertebræ have no cervical ribs. [illustration: fig. united atlas and axis of ornithocheirus (cambridge greensand)] the articular surfaces between the bodies of the vertebræ, in the neck, are transversely oval. the middle part of this articular joint is made by the body of the vertebra; its outer parts are in the neural arch. in front this surface is a hollow channel, often more depressed than in any other animals. the corresponding surface behind is convex, with a process on each side at its lower outer angles (fig. ). it is a modification of the cup-and-ball form of vertebral articulation, which at the present day is eminently reptilian. serpents and crocodiles have the articulations similarly vertical, but in both the form of the articulation is a circle. in lizards the articular cup is usually rather wider than deep, when the cup and ball are developed in the vertebræ; it differs from the vertical condition in pterodactyles in being oblique and much narrower from side to side. only among crocodiles and hatteria is there a double articulation for the cervical rib, though in neither order have rib or vertebra in the neck the bird-like proportions which are usual in these animals. pterodactyles show no resemblance to birds in this vertebral articulation. a bird has the corresponding surface concave from side to side in front, but it is also convex from above downward, producing what is known as the saddle-shaped form which is peculiarly avian, being found in existing birds except in part of the back in penguins. it is faintly approximated to in one or two neck vertebræ in man. professor williston remarks that in the toothless pterodactyles of kansas the hinder ball of the vertebral articulation is continued downward and outward as a concave articulation upon the processes at its outer corners. there are no mammals with a cup-and-ball articulation between the vertebræ, so that for what it is worth the character now described in ornithosaurs is reptilian, when judged by comparison with existing animals. [illustration: fig. . cervical vertebra of ornithocheirus from the cambridge greensand] low down on each side of the vertebra, at the junction of its body with the neural arch, is a large ovate foramen, transversely elongated, and often a little impressed at the border, which is the entrance of the air cell into the bone. these foramina are often one-third of the length of the neck vertebræ in specimens from the cambridge greensand, where the neck bones vary from three-quarters of an inch to about two and a half inches in length, and in extreme forms are as wide as long. the width of the interspace between the foramina is one-half the width of the vertebræ, though this character varies with different genera and species. several species from the solenhofen slate have the neck long and slender, on the type of the flamingo. in others the neck is thick and short--in the _scaphognathus crassirostris_ and _pterodactylus spectabilis_. some genera with slender necks have the bones preserved with a curved contour, such as might suggest a neck carried like that of a llama or a camel. the neck is occasionally preserved in a curve like a capital #s#, as though about to be darted forward like that of a bird in the act of striking its prey. the genera of pterodactyles with short necks may have had as great mobility of neck as is found among birds named ducks and divers; but those pterodactyles with stout necks, such as dimorphodon and ornithocheirus, in which the vertebræ are large, appear to have been built more for strength than activity, and the neck bones have been chiefly concerned in the muscular effort to use the fighting power of the jaws in the best way. the back the region of the back in a pterodactyle is short as compared with the neck, and relatively is never longer than the corresponding region in a bird. the shortness results partly from the short length of the vertebræ, each of which is about as long as wide. there is also a moderate number of bones in the back. in most skeletons from solenhofen these vertebræ between the neck and girdle of hip bones number from twelve to sixteen. they have a general resemblance in form to the dorsal vertebræ in birds. the greatest number of such vertebræ in birds is eleven. the number is small because some of the later vertebræ in birds are overlapped by the bones of the hip girdle, which extend forward and cover them at the sides, so that they become blended with the sacrum. this region of the skeleton in the dimorphodon from the lias is remarkable for the length of the median process, named the neural spine, which is prolonged upward like the spines of the early dorsal vertebræ of horses, deer, and other mammals. in this character they differ from living reptiles, and parallel some dinosaurs from the weald. the bones of the back in ornithocheirus from the cambridge greensand show the under side to be well rounded, so that the articular surfaces between the vertebræ, though still rather wider than deep, are much less depressed than in the region of the neck. the neural canal for the spinal cord has become larger and higher, and the sides of the bone are somewhat compressed. strong transverse processes for the support of the ribs are elevated above the level of the neural canal, at the sides of vertebræ compressed on the under sides, and directed outward. between these lateral horizontal platforms is the compressed median neural spine, which varies in vertical height. the articulation of the ribs is not seen clearly. isolated ribs from the stonesfield slate have double-headed dorsal ribs, like those of birds. in some specimens from the solenhofen slate like the scaphognathus, in the university museum at bonn, dorsal ribs appear to be attached by a notch in the transverse process of the dorsal vertebra, which resembles the condition in crocodiles. variations in the mode of attachment of ribs among mammals may show that character to be of subordinate importance. von meyer has described the first pair of ribs as frequently larger than the others, and there appear in rhamphorhynchus to be examples preserved of the sternal ribs, which connect the dorsal ribs with the sternum. six pairs have been counted. a more interesting feature in the ribs consists in the presence behind the sternum, which is shorter than the corresponding bone in most birds, of median sternal ribs. they are slender #v#-shaped bones in the middle line of the abdomen, which overlapped the ends of the dorsal ribs like the similar sternal bones of reptiles. such structures are unknown among birds and mammals. there is no trace in the dorsal ribs of the claw-like process, which extends laterally from rib to rib as a marked feature in many birds. its presence or absence may not be important, because it is represented by fibro-cartilage in the ribs of crocodiles, and may be a small cartilage near the head of the rib in serpents, and is only ossified in some ribs of the new zealand reptile hatteria. so that it might have been present in a fossil animal without being ossified and preserved. although the structure is associated with birds, it is possibly also represented by the great bony plates which cover the ribs in chelonians, and combine to form the shield which covers the turtle's back. the structure is as characteristic of reptiles as of birds, but is not necessarily associated with either. [illustration: fig. the upper figures show the side and back of a dorsal vertebra of ornithocheirus compared with corresponding views of the side and back of a dorsal vertebra of a crocodile] there are two remarkable modifications of the early dorsal vertebræ in some of the cretaceous pterodactyles. first, in the genus ornithodesmus from the weald the early dorsal vertebræ are blended together into a continuous mass, like that which is found in the corresponding region of the living frigate-bird, only more consolidated, and similar to that consolidated structure found behind the dorsal vertebræ, known as the sacrum, made by the blending of the vertebræ into a solid mass which supports the hip bones. secondly, in some of the cretaceous genera of pterodactyles of europe and america the vertebræ in the front part of the back are similarly blended, but their union is less complete; and in genera ornithocheirus and ornithostoma--the former chiefly english, the latter chiefly american--the sides of the neural spines are flattened to form an oval articular surface on each side, which gives attachment to the flattened ends of their shoulder-blade bones named the scapulæ. this condition is found in no other animals. three vertebræ appear to have their neural arches thus united together. the structure so formed may be named the notarium to distinguish it from the sacrum. sacrum for some mysterious reason the part of the backbone which lies between the bones of the hips and supports them is termed the sacrum. among living reptiles the number of vertebræ in this region is usually two, as in lizards and crocodiles. there are other groups of fossil reptiles in which the number of sacral vertebræ is in some cases less and in other cases more. there is, perhaps, no group in which the sacrum makes a nearer approach to that of birds than is found among these pterodactyles, although there are more sacral vertebræ in some dinosaurs. in birds the sacral vertebræ number from five to twenty-two. in bats the number is from five to six. in some solenhofen species, such as _pterodactylus dubius_ and _p. kochi_ and _p. grandipelvis_, the number is usually five or six. the vertebræ are completely blended. the pneumatic foramina in the sacrum, so far as they have been observed, are on the under sides of the transverse processes; while in the corresponding notarial structure in the shoulder girdle the foramina are in front of the transverse processes. almost any placental mammal in which the vertebræ of the sacral region are anchylosed together has a similar sacrum, which differs from that of birds in the more complete individuality of the constituent bones remaining evident. the transverse processes in front of the sacrum are wider than in its hinder part; so that the pelvic bones which are attached to it converge as they extend backward, as among mammals. the bodies of the vertebræ forming the sacrum are similar in length to those of the back. each transverse process is given off opposite the body of its own vertebra, but from a lower lateral position than in the region of the back, in which the vertebræ are free. [illustration: fig. . sacrum of rhamphorhynchus showing the complete blending of the vertebræ and ribs as in a bird, with the well-defined iliac bones, produced chiefly in front of the acetabulum for the head of the femur.] the hip bones are closely united with the sacrum by bony union, and rarely appear to come away from the sacral vertebræ, as among mammals and reptiles, though this happens with the lias pterodactyles. in the stonesfield slate and solenhofen slate the slender transverse processes from the vertebræ blend with the ilium of the hip girdle, and form a series of transverse foramina on each side of the bodies of the vertebræ. in the cambridge greensand genera the part of the ilium above the acetabulum for the articular head of the femur appears to be always broken away, so that the relation of the sacrum to the pelvis has not been observed. this character is no mark of affinity, but only shows that ossification obliterated sutures among these animals in the same way as among birds. the great difference between the sacrum of a pterodactyle and that of a bird has been rendered intelligible by the excellent discussion of the sacral region in birds made by professor huxley. he showed that it is only the middle part of the sacrum of a chicken which corresponds to the true sacrum of a reptile, and comprises the five shortest of the vertebræ; while the four in front correspond to those of the lower part of the back, which either bear no ribs or very short ribs, and are known as the lumbar region in mammals, so that the lower part of the back becomes blended with the sacrum, and thus reduces the number of dorsal vertebræ. similarly the five vertebræ which follow the true sacral vertebræ are originally part of the tail, and have been blended with the other vertebræ in front, in consequence of the extension along them of the bird's hip bones. this interpretation helps to account for the great length of the sacrum in many birds, and also explains in part the singular shortness of the tail in existing birds. the ornithosaur sacrum has neither the lumbar nor the caudal portions of the sacrum of a bird. the tail the tail is perhaps the least important part of the skeleton, since it varies in character and length in different genera. the short tails seen in typical pterodactyles include as few as ten vertebræ in _pterodactylus grandipelvis_ and _p. kochi_, and as many as fifteen vertebræ in _pterodactylus longirostris_. the tails are more like those of mammals than existing birds, in which there are usually from six to ten vertebræ terminating in the ploughshare bone. but just as some fossil birds, like the archæopteryx, have about twenty long and slender vertebræ in the tail, so in the pterodactyle rhamphorhynchus this region becomes greatly extended, and includes from thirty-eight to forty vertebræ. in dimorphodon the tail vertebræ are slightly fewer. the earliest are very short, and then they become elongated to two or three times the length of the early tail vertebræ, and finally shorten again towards the extremity of the tail, where the bones are very slender. in all long-tailed ornithosaurians the vertebræ are supported and bordered by slender ossified ligaments, which extend like threads down the tail, just as they do in rats and many other mammals and in some lizards. professor marsh was able to show that the extremity of the tail in rhamphorhynchus sometimes expands into a strong terminal caudal membrane of four-sided somewhat rhomboidal shape. he regards this membrane as having been placed vertically. it is supported by delicate processes which represent the neural spines of the vertebræ prolonged upward. they are about fifteen in number. a corresponding series of spines on the lower border, termed chevron bones, equally long, were given off from the junctions of the vertebræ on their under sides, and produced downward. this vertical appendage is of some interest because its expansion is like the tail of a fish. it suggests the possibility of having been used in a similar way to the caudal fin as an organ for locomotion in water, though it is possible that it may have also formed an organ used in flight for steering in the air. [illustration: fig. . extremity of the tail of _rhamphorhynchus phyllurus_ (marsh) showing the processes on the upper and under sides of the vertebræ which make the terminal leaf-like expansion] the tail vertebræ from the cambridge greensand are mostly found isolated or with not more than four joints in association. they are very like the slender type of neck vertebræ seen in long-necked pterodactyles, but are depressed, and though somewhat wider are not unlike the tail vertebræ of the rhamphorhynchus. the pneumatic foramen in them is a mere puncture. they have no transverse processes or neural spines, nor indications of ribs, or chevron bones. the hindermost specimens of tail vertebræ observed have the neural arch preserved to the end, as among reptiles; whereas in mammals this arch becomes lost towards the end of the tail. the processes by which the vertebræ are yoked together are small. there is nothing to suggest that the tail was long, except the circumstance that the slender caudal vertebræ are almost as long as the stout cervical vertebræ in the same animal. no small caudal vertebræ have ever been found in the cambridge greensand. the tail is very short, according to professor williston, in the toothless ornithostoma in the chalk of kansas. chapter x the hip-girdle and hind limb the bones of the hip-girdle form a basin which incloses and protects the abdominal vital organs. it consists on each side of a composite bone, the unnamed bones--_ossa innominata_ of the older anatomists--which are each attached to the sacrum on their inner side, and on the outer side give attachment to the hind limbs. as a rule three bones enter into the borders of this cup, termed the acetabulum, in which the head of the thigh bone, named the femur, moves with a more or less rotary motion. there are a few exceptions in this division of the cup between three bones, chiefly among salamanders and certain frogs. in crocodiles the bone below the acetabular cup is not divided into two parts. and in certain plesiosaurs from the oxford clay--murænosaurus--the actual articulation appears to be made by two bones--the ilium and ischium. the three bones which form each side of the pelvis are known as the ilium, or hip bone, sometimes termed the aitch bone; secondly, the ischium, or sitz bone, being the bone by which the body is supported in a sitting position; and thirdly the pubis, which is the bone in front of the acetabulum. the pubic bones meet in the middle line of the body on the under side of the pelvis in man, and on each side are partly separated from the ischia by a foramen, spoken of as the obturator foramen, which in pterodactyles is minute and almost invisible, when it exists. there is often a fourth bony element in the pelvis. in some salamanders a single cartilage is directed forward, and forked in front. according to professor huxley something of this kind is seen in the dog. the pair of bones which extend forward in front of the pelvis in crocodiles may be of the same kind, in which case they should be called prepubic bones. but among the lower mammals named marsupials a pouch is developed for the protection of the young and supported by two slender bones attached to the pubes, and these bones have long been known as marsupial bones. in a still lower group of mammalia named monotremata, which lay eggs, and in many ways approximate to reptiles and birds, stronger bones are developed on the front edge of the pubes, and termed prepubic bones. they do not support a marsupium. naturalists have been uncertain as to the number of bones in the pelvis of pterodactyles, because the bones blend together early in life, as in birds. some follow the amphibian nomenclature, and unite the ischium and pubis into one bone, which is then termed ischium, when the prepubis is termed the pubis, and regarded as removed from the acetabulum. there is no ground for this interpretation, for the sutures are clear between the three pelvic bones in the acetabulum in some specimens, like _cycnorhamphus fraasii_, from solenhofen, and some examples of ornithocheirus from the cambridge greensand. pterodactyles all have prepubic bones, which are only known in ornithorhynchus and echidna among mammals, and are absent from the higher mammals and birds. they are unknown in any other existing animals, unless present in crocodiles, in which ischium and pubis are always undivided. therefore it is interesting to examine the characters of the ornithosaurian pelvis. the acetabulum for the head of the femur is imperforate, being a simple oval basin, as in chelonian reptiles and the higher mammals. it never shows the mark of the ligamentous attachment to the head of the femur, which is seen in mammals. in birds the acetabulum is perforated, as in many of the fossils named dinosaurs, and in monotremata. [illustration: fig. . comparison of the left side of the pelvis in a bird and a pterodactyle] secondly, the ilium is elongated, and extends quite as much in front of the acetabulum as behind it. the bone is not very deep in this front process. among existing animals this relation of the bone is nearer to birds than to any other type, since birds alone have the ilium extended from the acetabulum in both directions. the form of the pterodactyle ilium is usually that of the embryo bird, and its slender processes compare in relative length better with those of the unhatched fowl and apteryx of new zealand than with the plate-like form in adult birds. in mammals the ilium is directed forward, and even in the cape ant-eater orycteropus there is only an inappreciable production of the bone backward behind the acetabulum. among reptiles the general position of the acetabulum is at the forward termination of the ilium, though the crocodile has some extension of the bone in both directions, without forming distinct anterior and posterior processes. this anterior and posterior extension of the ilium is seen in the theriodont reptiles of russia and of south africa, as well as in dinosaurs. [illustration: fig. . left pelvic bones with prepubic bone in _pterodactylus longirostris_] thirdly, in all pterodactyles the ischium and pubis are more or less completely blended into a sheet of bone, unbroken by perforation, though there is usually a minute vascular foramen; or the lower border may be notched between the ischium and the pubis, as in some of the solenhofen species, and the pubis does not reach the median line of the body. but in dimorphodon the pelvic sheet of bone is unbroken by any notch or perforation. the notch between the ischium and pubis is well marked in _pterodactylus longirostris_, and better marked in _pterodactylus dubius_, _cycnorhamphus fraasii_, and rhamphorhynchus. the fossil animals which appear to come nearest to the pterodactyles in the structure of the pelvis are theriodonts from the permian rocks of russia. the type known as rhopalodon has the ilium less prolonged front and back, and is much deeper than in any pterodactyle; but the acetabulum is imperforate, and the ischium and pubis are not always completely separated from each other by suture. in the pelvis referred to the theriodont deuterosaurus there is some approximation to the pelvis of rhamphorhynchus and of _pterodactylus dubius_ in the depth of the division between the pubis and ischium. [illustration: fig. pelvis and prepubic bones of rhamphorhynchus on the left-hand side the two prepubic bones are separate. on the right-hand they are united into a transverse bar which overlaps the front of pelvis seen from the under side] there are three modifications of the ornithosaurian pelvis. first, the type of rhamphorhynchus, in which the pubis and ischium are inclined somewhat backward, and in which the two prepubic bones are triangular, and are often united together to form a transverse bow in front of the pubic region. secondly, there is the ordinary form of pelvis in which the pubis and ischium usually unite with each other down their length, as in dimorphodon, but sometimes, as in _pterodactylus dubius_, divide immediately below the acetabulum. all these types possess the paddle-shaped prepubic bones, which are never united in the median line. thirdly, there is the cretaceous form indicated by ornithocheirus and ornithostoma, in which the posterior half of the ilium is modified in a singular way, since it is more elevated towards the sacrum than the anterior half, suggesting the contour of the upper border of the ilium in a lizard. without being reptilian--the anterior prolongation of the bone makes that impossible--it suggests the lizards. this type also possesses prepubic bones. they appear, according to professor williston, to be more like the paddle-shaped bones of pterodactylus than like the angular bones in rhamphorhynchus. the prepubic bones are united in the median line as in rhamphorhynchus. but their median union in that genus favours the conclusion that the bones were united in the median line in all species, though they are only co-ossified in these two families. [illustration: fig. . the pelvic bones of an alligator seen from below the bones in front are here regarded as prepubic, but are commonly named pubic] this median union of the prepubic bones is a difference from those mammals like the ornithorhynchus and echidna, which approach nearest to the reptilia. in them the prepubic bones have a long attachment to the front margin of the pubis, and extend their points forward without any tendency for the anterior extremities to approximate or unite. the marsupial mammals have the same character, keeping the marsupial bones completely distinct from each other at their free extremities. the only existing animals in which an approximation is found to the prepubic bones in pterodactyles are crocodiles, in bones which most writers term the pubic bones. this resemblance, without showing any strong affinity with the crocodilia, indicates that crocodiles have more in common with the fossil flying animals than any other group of existing reptiles; for other reptiles all want prepubic bones, or bones in front of the pubic region. the hind limb the hind limb is exceptionally long in proportion to the back. this is conspicuous in the skeletons of the short-tailed pterodactyles, and is also seen in dimorphodon. in rhamphorhynchus the hind limb is relatively much shorter, so that the animal, when on all fours, may have had an appearance not unlike a bat in similar position. the limb is exceptionally short in the little _ptenodracon brevirostris_. the bones of the hind limb are exceptionally interesting. one remarkable feature common to all the specimens is the great elongation of the shin bones relatively to the thigh bones. the femur is sometimes little more than half the length of the tibia, and always shorter than that bone. the proportions are those of mammals and birds. some mammals have the leg shorter than the thigh, but mammals and birds alone, among existing animals, have the proportions which characterise pterodactyles. the foot appears to have been applied to the ground not always as in a bird, but more often in the manner of reptiles, or mammals in which the digits terminate in claws. the femur [illustration: fig. . the femur on the right is a front view of femur of a bear. in the middle are front and side views of the femur of ornithocheirus. on the left is the femur of echidna. these comparisons illustrate the mammalian characters of the pterodactyle thigh bone] the thigh bone, on account of the small size of many of the specimens, is not always quite clear evidence as an indication of technical resemblance to other animals. the bone is always a little curved, has always a rounded, articular head, and rounded distal condyles. its most remarkable features are shown in the large, well-preserved specimens from the cambridge greensand. the rounded, articular head is associated with a constricted neck to the bone, followed by a comparatively straight shaft with distal condyles, less thickened than in mammals. no bird is known, much less any reptile, with a femur like ornithocheirus. only among mammals is a similar bone known with a distinct neck; and only a few mammals have the exceptional characters of the rounded head and constricted neck at all similar to the cretaceous pterodactyles. a few types, such as the higher apes, the hyrax, and animals especially active in the hind limb, have a femur at all resembling the pterodactyle in the pit for the obturator externus muscle, behind the trochanter major, such as is seen in a small femur from ashwell. the femur varies in different genera, so as to suggest a number of mammalia rather than any particular animal for comparison. these approximations may be consequences of the ways in which the bones are used. when functional modifications of the skeleton are developed, so as to produce similar forms of bones, the muscles to which they give attachment, which act upon the bones, and determine their growth, are substantially the same. in the _pterodactylus longirostris_ the femur corresponds in length to about eleven dorsal vertebræ. the end next the shin bone is less expanded than is usual among mammals, and rather suggests an approach to the condition in crocodiles, in the moderate thickness and breadth of the articular end, and the slight development of the terminal pulley-joint. one striking feature of the femur is the circumstance that the articular head, as compared with the distal end, is directed forward and very slightly inward and upward. so that allowing for the outward divergence of the pelvic bones, as they extend forward, there must have been a tendency to a knock-kneed approximation of the lower ends of the thigh bones, as in mammals and birds, rather than the outward divergence seen in reptiles. apparently the swing of the leg and foot, as it hung on the distal end of the femur, must have tended rather to an inward than to an outward direction, so that the feet might be put down upon the same straight line; this arrangement suggests rapid movement. [illustration: fig. . comparison of the tibia and fibula in ornithosaur and vulture] tibia and fibula in _pterodactylus longirostris_ the tibia is slender, more than a fifth longer than the femur. a crest is never developed at the proximal end, like that seen in the guillemot and diver and other water birds. the bone is of comparatively uniform thickness down the shaft in most of the solenhofen specimens, as in most birds. at the distal end the shin bone commonly has a rounded, articular termination, like that seen in birds. this is conspicuous in the _pterodactylus grandis_. in other specimens the tarsal bones, which form this pulley, remain distinct from the tibia; and the upper row of these bones appears to consist of two bones, like those which in many dinosaurs combine to form the pulley-like end of the tibia which represents the bird's drum-stick bone. they correspond with the ankle bones in man named astragalus and os calcis. complete english specimens of tibia and fibula are found in the genus dimorphodon from the lias, in which the terminal pulley of the distal end has some expansion, and is placed forward towards the front of the tibia, as in some birds. the rounded surface of the pulley is rather better marked than in birds. the proximal end of the shaft is relatively stout, and is modified by the well-developed fibula, which is a short external splint bone limited to the upper half of the tibia, as in birds; but contributing with it to form the articular surface for the support of the lower end of the femur, taking a larger share in that work than in birds. frequently there is no trace of the fibula visible in solenhofen specimens as preserved; or it is extremely slender and bird-like, as in _pterodactylus longirostris_. in rhamphorhynchus it appears to extend the entire length of the tibia, as in dinosaurs. in the specimens from the cambridge greensand there is indication of a small proximal crest to the tibia with a slight ridge, but no evidence that this is due to a separate ossification. the patella, or knee-cap, is not recognised in any fossil of the group. there is no indication of a fibula in the specimens thus far known from the chalk rocks either of kansas in america, or in england. the region of the tarsus varies from the circumstance that in many specimens the tibia terminates downward in a rounded pulley, like the drum-stick of a bird; while in other specimens this union of the proximal row of the tarsal bones with the tibia does not take place, and then there are two rows of separate tarsal bones, usually with two bones in each row. when the upper row is united with the tibia the lower row remains distinct from the metatarsus, though no one has examined these separate tarsal bones so as to define them. the foot [illustration: fig. . metatarsus and digits in three types of ornithosaurs] the foot sometimes has four toes, and sometimes five. there are four somewhat elongated, slender metatarsal bones, which are separate from each other and never blended together, as in birds. there has been a suspicion that the metatarsal bones were separate in the young archæopteryx. in the young of many birds the row of tarsal bones at the proximal end of the metatarsus comes away, and there is a partial division between the metatarsal bones, though they remain united in the middle. and among penguins, in which the foot bones are applied to the ground instead of being carried in the erect position of ordinary birds, there is always a partial separation between the metatarsal bones, though they become blended together. the pterodactyle is therefore different from birds in preserving the bones distinct through life, and this character is more like reptiles than mammals. the individual bones are not like those of dinosaurs, and diverge in rhamphorhynchus as though the animals were web-footed. there is commonly a rudimentary fifth metatarsal. it is sometimes only a claw-shaped appendage, like that seen in the crocodile. it is sometimes a short bone, completely formed, and carrying two phalanges in solenhofen specimens: though no trace of these phalanges is seen in the large toothless pterodactyles from the cretaceous rocks of north america. in the _pterodactylus longirostris_ the number of foot bones on the ordinary digits is two, three, four, five, as in lizards; but the short fifth metatarsal has only two toe bones. in dimorphodon the fifth digit was bent upward, and supported a membrane for flight. there are slight variations in the number of foot bones. in the species _pterodactylus scolopaciceps_ the number of bones in the toes follows the formula two, three, three, four. in _pterodactylus micronyx_ the number is two, three, three, three. the terminal claws are much less developed than is usual with birds; and there is a difference from bats in the unequal length of the digits. taken as a whole, the foot is perhaps more reptilian than avian, and in some genera is crocodilian. the foot is the light foot of an active animal. von meyer thought that the hind legs were too slender to enable the animal to walk on land; and professor williston, of the university of kansas, remarks that the rudimentary claws and weak toes indicate that the animal could not have used the feet effectively for grasping, while the exceedingly free movement of the femur indicates great freedom of movement of the hind legs; and he concludes that the function of the legs was chiefly for guidance in flight through their control over the movements, and expresses his belief that the animal could not have stood upon the ground with its feet. there may be evidence to sustain other views. if the limb bones are reconstructed, they form limbs not wanting in elegance or length. if it is true, as professor williston suggests, that the weight of his largest animals with the head three feet long, and a stretch of wing of eighteen or nineteen feet, did not exceed twenty pounds, there can be no objection to regarding these animals as quadrupeds, or even as bipeds, on the ground of the limbs lacking the strength necessary to support the body. the slender toes of many birds, and even the two toes of the ostrich, may be thought to give less adequate support for those animals than the metatarsals and digits of pterodactyles. chapter xi shoulder-girdle and fore limb sternum the sternum is always a distinguishing part of the bony structure of the breast. in crocodiles it is a cartilage to which the sternal ribs unite; and upon its front portion a flat knife-like bone called the interclavicle is placed. in lizards like the chameleon, it is a lozenge-shaped structure of thin bony texture, also bearing a long interclavicle, which supports the clavicular bones, named collar bones in man, which extend outward to the shoulder blades. among mammals the sternum is usually narrow and flat, and often consists of many successive pieces in the middle line, on the under side of the body. among bats the anterior part is somewhat widened from side to side, to give attachment to the collar bones, but the sternum still remains a narrow bone, much narrower than in dolphins, and not differing in character from many other mammals, notwithstanding the bat's power of flight. the bone develops a median keel for the attachment of the muscles of the breast, but something similar is seen in burrowing insectivorous mammals like the moles. so that, as von meyer remarked, the presence of a keel on the sternum is not in itself sufficient evidence to prove flight. among birds the sternum is greatly developed. broad and short in the ostrich tribe, it is devoid of a keel; and therefore the keel, if present in a bird, is suggestive of flight. the keel is differently developed according to the mode of attachment of the several pectoral muscles which cover a bird's breast. in several water birds the keel is strongly developed in front, and dies away towards the hinder part of the sternum, as in the cormorant and its allies. the sternum in german pterodactyles is most nearly comparable to these birds. [illustration: fig. . comparison of the sternum] in the solenhofen slate the sternum is fairly well preserved in many ornithosaurs. it is relatively shorter than in birds, and is broader than long; but not very like the sternum of reptile or mammal in form. the keel is limited to the anterior part of the shield of the sternum, as in merganser and the cormorant, and is prolonged forward for some distance in advance of it. von meyer noticed the resemblance of this anterior process to the interclavicle of the crocodile in position; but it is more like the keel of a bird's sternum, and is not a separate bone as in reptiles. in pterodactyles from the cretaceous rocks, the side bones, called coracoids, are articulated to saddle-shaped surfaces at the hinder part of the base of this keel, which are parallel in ornithocheirus, as in most birds, but overlap in ornithodesmus, as in herons and wading birds. [illustration: fig. . sternum in ornithocheirus from the cambridge greensand showing the strong keel and the facets for the coracoid bones on its hinder border above the lateral constrictions] the keel was pneumatic, and when broken is seen to be hollow, and appears to have been exceptionally high in rhamphorhynchus, a genus in which the wing bones are greatly elongated. von meyer found in rhamphorhynchus on each side of the sternum a separate lateral plate with six pairs of sternal ribs, which unite the sternum with the dorsal ribs, as in the young of some birds. the hinder surface of the sternum is imperfectly preserved in the toothless pterodactyles of kansas. professor williston states that the bone is extremely thin and pentagonal in outline, projecting in front of the coracoids, in a stout, blunt, keel-like process, similar to that seen in the pterodactyles of the cambridge greensand. american specimens have not the same notch behind the articulation for the coracoid to separate it from the transverse lateral expansion of the sternal shield. the lateral margin in the cambridge greensand specimens figured by professor owen and myself is broken; but professor williston had the good fortune to find on the margin of the sternum the articular surfaces which gave attachment to the sternal ribs. the margin of the sternal bone thickens at these facets, four of which are preserved. the sternum in ornithostoma was about four and a half inches long by less than five and a half inches wide. the median keel extends forward for rather less than two inches, while in the smaller cambridge species of ornithocheirus it extends forward for less than an inch and a half. a sternum of this kind is unlike that of any other animal, but has most in common with a bird; and may be regarded as indicating considerable power of flight. the bone cannot be entirely attributed to the effect of flight, since there is no such expanded sternal shield in bats. the small number of sternal ribs is even more characteristic of birds than mammals or reptiles. the shoulder-girdle the bones which support the fore limb are one of the distinctive regions of the skeleton defining the animal's place in nature. among most of the lower vertebrata, such as amphibians and reptiles, the girdle is a double arch--the arch of the collar bone or clavicles in front, and the arch of the shoulder-blade or scapula behind. the clavicular arch, when it exists, is formed of three or five parts--a medium bar named the interclavicle, external to which is a pair of bones called clavicles, reaching to the front of the scapulæ when they are present; and occasionally there is a second pair of bones called supraclavicles, extending from the clavicles up the front margins of the scapulæ. thus the clavicular arch is placed in front of the scapular arch. the supraclavicles are absent from all living reptiles, and the clavicles are absent from crocodiles. the interclavicle is absent from all mammals except echidna and ornithorhynchus. clavicles also may be absent in some orders of mammals. hence the clavicular arch may be lost, though the collar bones are retained in man. the scapular arch also is more complicated and more important in the lower than in the higher vertebrata. it may include three bones on each side named coracoid, precoracoid, and scapula. but in most vertebrates the coracoid and precoracoid appear never to have been segmented so as to be separated from each other; and it is only among extinct types of reptiles, which appear to approximate to the monotreme mammals, that separate precoracoid bones are found; though among most mammals, probably, there are stages of early development in which precoracoids are represented by small cartilages, though few mammals except edentata like the sloths and ant-eaters, retain even the coracoids as distinct bones. therefore, excepting the edentata and the monotremes, the distinctive feature of the mammalian shoulder-girdle appears to be that the limbs are supported by the shoulder-blades, termed the scapulæ. among reptiles there are several distinct types of shoulder-girdle. chelonians possess a pair of bones termed coracoids which have no connexion with a sternum; and their scapulæ are formed of two widely divergent bars, divided by a deeper notch than is found in any fossil reptiles. among lizards both scapula and coracoid are widely expanded, and the coracoid is always attached to the sternum. chameleons have the blade of the scapula long and slender, but the coracoid is always as broad as it is long. crocodiles have the bone more elongated, so that it has somewhat the aspect of a very strong first sternal rib when seen on the ventral face of the animal. the bone is perforated by a foramen, which would probably lie in the line of separation from the precoracoid if any such separation had ever taken place. the scapula, or shoulder-blade, of crocodiles is a similar flat bone, very much shorter than the scapula of a chameleon, and more like that of the new zealand hatteria. thus there is very little in common between the several reptilian types of shoulder-girdle. [illustration: fig. . comparison of scapula and coracoid in three pterodactyles and a bird] in birds the apparatus for the support of the wings has a far-off resemblance to the crocodilian type. the coracoid bones, instead of being directed laterally outward and upward from the sternum, as among crocodiles, are directed forward, so as to prolong the line of the breast bone, named the sternum. the bird's coracoid is sometimes flattened towards the breast bone among swans and other birds; yet as a rule the coracoid is a slender bar, which combines with the still more slender and delicate blade of the scapula, which rests on the ribs, to make the articulation for the upper arm bone. among reptiles the scapula and coracoid are more or less in the same straight line, as in the ostrich, but in birds of flight they meet at an angle which is less than a right angle, and where they come in contact the external surface is thickened and excavated to make the articulation for the head of the humerus. there is nothing like this shoulder-girdle outside the class of birds, until it is compared with the corresponding structure in these extinct animals called pterodactyles. the resemblance between the two is surprising. it is not merely the identity of form in the coracoid bone and the scapula, but the similar angle at which they meet and the similar position of the articulation for the humerus. everything in the pterodactyle's shoulder-girdle is bird-like, except the absence of the representative of the clavicles, that forked #v#-shaped bone of the bird which in scientific language is known as the furculum, and is popularly termed the "merry-thought." this kind of shoulder-girdle is found in the genera from the lias and the oolitic rocks, both of this country and germany. in the cretaceous rocks the scapula presents, in most cases, a different appearance. the coracoid is an elongated, somewhat triangular bone, compressed on the outer margin as in birds, but differing alike from birds and other pterodactyles in not being prolonged forward beyond the articulation for the humerus. in these cretaceous genera, toothed and toothless alike, the articulation for the upper arm bone truncates the extremity of the coracoid, so that the bone is less like that of a bird in this feature. perhaps it shows a modification towards the crocodilian direction. the scapula, which unites with the coracoid at about a right angle, is similarly truncated by the articular surface for the humerus; but the bone is somewhat expanded immediately beyond the articulation, and compressed; and instead of being directed backward, it is directed inward over the ribs to articulate with the neural arches of the early dorsal vertebræ in the genera found in strata associated with the chalk. as the bone approaches this articulation, it thickens and widens a little, becoming suddenly truncated by an ovate facet, which exactly corresponds to the transversely ovate impression, concave from front to back, which is seen in the neural arches of the dorsal vertebræ on which it fits. this condition is not present in all cretaceous pterodactyles. it does not occur in the kansas fossil, named by professor marsh, nyctodactylus. and it appears to be absent from the pterodactyles of the english weald, named ornithodesmus. [illustration: fig. . the notarium an ossification which gives attachment to the scapulæ seen in the early dorsal vertebra of ornithocheirus (from the cambridge greensand)] [illustration: fig. . restoration of the shoulder-girdle in the cretaceous ornithocheirus showing how the scapulæ articulate with a vertebra and the articulation of the coracoids with the sternum. the humeral articulation with the coracoid is unlike the condition shown in other ornithosaurs] there is no approach to this transverse position of the scapulæ among birds. and while the form of the bones in the older genera of ornithosaurs is singularly bird-like, the angular arrangement in this cretaceous genus is obtained by closely approximating the articulations on the sternum, so that the coracoids extend outward as in reptiles, instead of forward as in birds; and the extremities of the scapulæ similarly approximate towards each other. this rather recalls the relative positions of scapula and coracoid among crocodiles. if crocodile and bird had been primitive types of animals instead of surviving types, it might almost seem as though there had been a cunning and harmonious blending of one with the other in evolving this form of shoulder-girdle. the fore limb the bones of the fore limb, generally, correspond in length with the similar parts of the hind limb. the upper arm bone corresponds with the upper leg bone, and the fore-arm bone is as long as the fore-leg bone; then differences begin. the bones which correspond to the back of the hand in man, termed the metacarpus, are variable in length in pterodactyles--sometimes very long and sometimes short. the wing metacarpal bone is always stout, and the others are slender. the extremity of the metacarpus was applied to the ground. three small digits of the hand are developed from the three small metacarpal bones, and terminate in large claws. the great wing finger was bent backward, and only touched the ground where it fitted upon the wing metacarpal bone. it appears sometimes to have been as long as the entire vertebral column. owing to the circumstance that the joint in the arm in pterodactyles was not at the wrist as among birds, but between the metacarpus and the phalanges, it follows that the fore limb was longer than the hind limb when the metacarpus was long; but the difference would not interfere with the movements of the animal, either upon four feet or on two feet, for in bats and birds the disproportion in length is greater. humerus or upper arm bone the first bone in the fore-arm, the humerus, is remarkable chiefly for the compressed crescent form of its upper articular end, which is never rounded like the head of the upper arm bone in man, and secondly for the great development of the external process of bone near that end, termed the radial crest. sir richard owen compared the bone to the humerus of both birds and crocodiles, but in its upper articular end the crocodile bone may be said to be more like a bird than it is like the pterodactyle. in flying reptiles the articular surface next to the shoulder-girdle is somewhat saddle-shaped, being concave from side to side above and convex vertically, while most animals with which it can be compared have the articular head of the bone convex in both directions. a remarkable exception to this general rule is found in some fossil animals from south africa, which, from resemblance to mammals in their teeth, have been termed theriodonts. they sometimes have the head of the bone concave from side to side and convex in the vertical direction. to this condition ornithorhynchus makes a slight approximation. the singular expansion of the structure called the radial crest finds no close parallel in reptiles, though crocodiles have a moderate crest on the humerus in the same position; and in theriodonts the radial crest extends much further down the shaft of the humerus. no bird has a radial crest of a similar kind, though it is prolonged some way down the shaft in archæopteryx. in pterodactyles it sometimes terminates outward in a smooth, rounded surface, which might have been articular if any structure could have articulated with it. there is also a moderate expansion of the bone on the ulnar side in some pterodactyles, so that the proximal end often incloses nearly three-fourths of an ovate outline. the termination of the radial crest is at the opposite end of this oval to the wider articular part of the head of the bone, in some specimens from the cambridge greensand. the radial crest is more extended in rhamphorhynchus. all specimens of the humerus show a twist in the length of the bone, so that the end towards the fore-arm, which is wider than the shaft, makes a right angle with the radial crest on the proximal end, which is not seen in birds. the shaft of the humerus is always stouter than that of the femur, though different genera differ in this respect. the humerus in genera from rocks associated with the chalk presents two modifications, chiefly seen in the characters of the distal end of the bone. one of these is a stout bone with a curiously truncated end where it joins the two bones of the fore-arm; and the other is more or less remarkable for the rounded form of the distal condyles. both types show distinct articular surfaces. the inner one is somewhat oblique and concave, the outer one rounded; the two being separated by a concave channel, so that the ulna makes an oblique articulation with the bone as in birds, and the radius articulates by a more or less truncated or concave surface. [illustration: fig. . comparison of the humerus in pterodactyle and bird] ulna and radius [illustration: fig. . comparison of the bones of the fore-arm in bird and ornithosaur] the bones of the fore-arm are similar to each other in size, and if there be any difference between them the ulna is slightly the larger. there is some evidence that in rhamphorhynchus the upper end of the ulna was placed behind the radius, probably in consequence of the mode of attachment of those bones to the humerus. the ulna abutted towards the inner and lower border, while the radius was towards the upper border, consequent upon the twist in the humerus. this condition corresponds substantially with the arrangement in birds, but differs from birds in the relatively more important part taken by the radius in making the articulation. the bones are compared in dimorphodon with the golden eagle drawn of the same size (fig. ). in birds the ulna supports the great feathers of the wing, and this may account for the size of the bone. the ulna is best seen at its proximal end in the specimens from the cambridge greensand, where there is a terminal olecranon ossification forming an oblique articulation, which frequently comes away and is lost. it is sometimes well preserved, and indicated by a suture. the examples of ulna from the lias show a slight expansion of the bone at both ends, and at the distal end toward the wrist the articulation is well defined, where the bone joins the carpus. the larger specimens of the bone are broken. the distal articular surface is only connected with the proximal end of the bone in small specimens: it always shows on the one margin a concavity, followed by a prominent boss, and an oblique articulation beyond the boss. on the side towards the radius, on the lower end of the shaft there is an angular ridge, which marks the line along which the ulna overlaps the radius. the lower end of the radius has a simple, slightly convex articulation, somewhat bean-shaped. no rotation of these bones on each other was possible as in man. there is a third bone in the fore-arm. this bone, named the pteroid, is commonly seen in skeletons from solenhofen. it was regarded by von meyer as having supported the wing membrane in flight. some writers have interpreted it as an essential part of the pterodactyle skeleton, and von meyer thought that it might possibly indicate a fifth digit in the hand. the only existing structure at all like it is seen in the south african insectivorous mammal named _chrysochloris capensis_, the golden mole, which also has three bones in the fore-arm, the third bone extending half-way up towards the humerus. in that animal the third bone appears to be behind the others and adjacent to the ulna. in the german fossils the pteroid articulated with a separate carpal or metacarpal bone, placed on the side of the arm adjacent to the radius, and the radius is always more inward than the ulna. if the view suggested by von meyer is adopted, this bone would be a first digit extending outward and backward towards the humerus. that view was adopted by professor marsh. it involves the interpretation of what has been termed the lateral carpal as the first metacarpal bone, which would be as short as that of a bird, but turned in the opposite direction backward. the first digit would then only carry one phalange, and would not terminate in a claw, but lie in the line of the tendon which supports the anterior wing membrane of a bird. the third bone in the fore-arm of chrysochloris does not appear to correspond to a digit. the bone is on the opposite side of the arm to the similar bone of a pterodactyle, and therefore cannot be the same structure in the golden mole. the interpretation which makes the pteroid bone the first digit has the merit of accounting for the fifth digit of the hand. all the structures of the hand are consistent with this view. the circumstance that the bone is rarely found in contact with the radius, but diverging from it, shows that it plays the same part in stretching the membrane in advance of the arm, that the fifth digit holds in supporting the larger wing membrane behind the arm. according to professor williston, the american toothless pterodactyle ornithostoma has but a single phalange on the corresponding first toe of the hind foot, and that bone he describes as long, cylindrical, gently curved, and bluntly pointed. there is some support for this interpretation; but i have not seen any english or german pterodactyles with only one phalange in the first toe. the wing in pterodactyles would thus be stretched between two fingers which are bent backward, the three intermediate digits terminating in claws. the carpus the wrist bones in the reptilia usually consist of two rows. in crocodiles, in the upper row there is a large inner and a small outer bone, behind which is a lunate bone, the remainder of the carpus being cartilaginous. only one carpal is converted into bone in the lower row. it is placed immediately under the smaller upper carpal. in chelonians, the turtle and tortoise group, the characters of the carpus vary with the family. in the upper row there are usually two short carpals, which may be blended, under the ulna; while the two under the radius are commonly united. the lower row is made up of several small bones. lizards, too, usually have three bones in the proximal row and five smaller bones in the distal row. the correspondence of the distal carpals with the several metacarpal bones of the middle hand is a well-known feature of the structure of the wrist. von meyer remarks that the carpus is made up of two rows of small bones in the solenhofen pterodactyles; while in birds there is one row consisting of two bones. the structure of the carpus is not distinct in all german specimens; but in the short-tailed solenhofen genera the bones in the two rows retain their individuality. in all the cretaceous genera the carpal bones of each row are blended into a single bone, so that two bones are superimposed, which may be termed the proximal and distal carpals. one specimen shows by an indication of sutures the original division of the distal carpal into three bones; and the separated constituent bones are very rarely met with. two bones of the three confluent elements contribute to the support of the wing metacarpal, and the third gives an articular attachment to the bone which extends laterally at the inner side of the carpus, which i now think may be the first metacarpal bone turned backward towards the humerus. the three component bones meet in the circular pneumatic foramen in the middle of the under side of the distal carpal. there is no indication of division of the proximal carpal in these genera into constituent bones. [illustration: fig. . carpus from ornithocheirus (cambridge greensand)] this condition is somewhat different from birds. in dr. rosenberg, of dorpat, showed that there is in the bird a proximal carpal formed of two elements, and a distal carpal also formed of two elements. therefore the two constituents of the distal carpal in the bird which blends in the mature animal with the metacarpus, forming the rounded pulley joint, may correspond with two of the three bones in the cretaceous pterodactyle _ornithocheirus._ the width of a proximal carpal rarely exceeds two inches, and that of a distal carpal is about an inch and three-quarters. two such bones when in contact would not measure more than one inch in depth. the lower surface shows that the wing had some rotary movement upon the carpus outward and backward. metacarpus [illustration: fig. . metacarpus in two ornithosaurs] the metacarpus consists of bones which correspond to the back of the hand. the first digit of the hand in clawed animals has the metacarpal bone short, or shorter than the others. among mammals metacarpal bones are sometimes greatly elongated; and a similar condition is found in pterodactyles, in which the metacarpal bone may be much longer than the phalange which is attached to it. two metacarpal bones appear to be singularly stouter than the others. the first bone of the first digit, if rightly determined, is much shorter than the others, and is, in fact, no longer than the carpus (fig. ). it is a flat oblong bone, attached to the inner side of the lower carpal, and instead of being prolonged distally in the same direction as the other metacarpal bones, is turned round and directed upward, so that its upper edge is flush with the base of the radius, and gives attachment to a bone which resembles a terminal phalange of the wing finger. according to this interpretation it is the first and only phalange in the first digit. the bone is often about half as long as the fore-arm, terminates upward in a point, is sometimes curved, and frequently diverges outward from the bones of the fore-arm, as preserved in the associated skeleton, being stretched towards the radial crest of the humerus. this mode of attachment of the supposed first metacarpal, which is true for all cretaceous pterodactyles, has not been shown to be the same for all those from the solenhofen slate. there is no greater anomaly in this metacarpal and phalange on the inner side being bent backward, than there is in the wing finger being bent backward on the outer side. the three slender intervening digits extend forward between them, as though they were applied to the ground for walking. the bone which is usually known as the wing metacarpal is frequently stouter at the proximal end towards the carpus than towards the phalange. at the carpal end it is oblong and truncated, with a short middle process, which may have extended into the pit in the base of the carpal bone; while the distal terminal end is rounded exactly like a pulley. there is great difference in the length of the metacarpus. in the american genus ornithostoma it is much longer than the fore-arm. in rhamphorhynchus it is remarkably short, though perhaps scarcely so short as in dimorphodon or in scaphognathus. the largest cretaceous examples are about two inches wide where they join the carpus. the bone is sometimes a little curved. between the first and fifth or wing metacarpal are the three slender metacarpal bones which give attachment to the clawed digits. they bear much the same relation to the wing metacarpal that the large metatarsal of a kangaroo has to the slender bones of the instep which are parallel to it. the facet for the wing metacarpal on the carpus is clearly recognised, but as a rule there is no surface with which the small metacarpals can be separately articulated. one or two exceptional specimens from the cambridge greensand appear to have not only surfaces for the wing metacarpal, but two much smaller articular surfaces, giving attachment to smaller metacarpals; while in one case there appears to be only one of these additional impressions. it is certain that all the animals from the lias and oolites have three clawed digits, but at present i have seen no evidence that there were three in the cretaceous genera, though professor williston's statements and restoration appear to show that the toothless pterodactyles have three. another difference from the oolitic types, according to professor williston, is in the length of the slender metacarpals of the clawed phalanges being about one-third that of the wing metacarpal, but this is probably due to imperfect ossification at the proximal end; for at the distal end the bones all terminated on the same level, showing that the four outer digits were applied to the ground to support the weight of the body. the corresponding bone in the horse and oxen is carried erect, so as to be in a vertical line with the bones of the fore-arm; and the same position prevails usually, though not invariably, with the corresponding bone in the hind limb, while in many clawed mammals the metacarpus and metatarsus are both applied upon the ground. in pterodactyles the metatarsal bones are preserved in the rock in the same straight line with the smaller bones of the foot, or make an angle with the shin bone, leading to the conviction that the bones of the foot were applied to the ground as in man, and sometimes as in the dog, and were thus modified for leaping. just as the human metacarpus is extended in the same line with the bones of the fore-arm, and the movement of jointing occurs where the fingers join the metacarpus, so pterodactyles also had these bones differently modified in the fore and hind limbs for the functions of life. the result is to lengthen the fore limb as compared with the hind limb by introducing into it an elevation above the ground which corresponds to the length of the metacarpus, always supposing that the animal commonly assumed the position of a quadruped when upon the earth's surface. this position of the metacarpus is a remarkable difference from birds, because when the bird's wing is at rest it is folded into three portions. the upper arm bone extends backward, the bones of the fore-arm are bent upon it so as to extend forward, and then at the wrist the third portion, which includes the metacarpus and finger bones, is bent backward. so that the metacarpus in the pterodactyle differs from birds in being in the same line as the bones of the fore-arm, whereas in birds it is in the same line with the digit bones of the hand. it is worthy of remark that in bats, which are so suggestive of pterodactyles in some features of the hand, the metacarpals and phalanges are in the same straight line; so that in this respect the bat is more like the bird. but pterodactyles in the relation of these bones to flight are quite unlike any other animal, and have nothing in common with the existing animals named reptiles. the hand from what has just been said it follows that the construction of the hand is unique. it may be contrasted with the foot of a bird. the bone which is called, in the language of anatomists, the tarso-metatarsus, and is usually free from feathers and covered with skin, is commonly carried erect in birds, so that the whole body is supported upon it; and from it the toes diverge outward. it is formed in birds of three separate bones blended together. in the fore limb of the pterodactyle the metacarpus has the same relation to the bones of the fore-arm that the metatarsus has to the corresponding bones of the leg in a bird. but the three metacarpal bones in the pterodactyle remain distinct from each other, perhaps because the main work of that region of the skeleton has devolved upon the digit called the wing finger, which is not recognised in the bird. in the pterodactyles from the solenhofen slate there is a progressive number of phalanges in the three small digits of the hand, which were applied to the ground. this number in the great majority of species follows the formula of two bones in the first, three bones in second, and four in the third; so that in the innermost of the clawed digits only one bone intervenes between the metacarpal and the claw. the fingers slightly increase in length with increase in number of bones which form them. [illustration: fig. . claw phalange from the hand in ornithocheirus. (half natural size)] [illustration: fig. . metacarpus and digits of the hand in birds with claws] the terminal claw bones are unlike the claws of birds or reptiles. they are compressed from side to side, and extremely deep and strong, with evidence of powerful attachment for ligaments, so that they rather resemble in their form and large size the claws of some of the carnivorous fossil reptiles, often grouped as dinosauria, such as have been termed aristosuchus and megalosaurus. in the hand of the ostrich the first and second digits terminate in claws, while the third is without a claw. but these claws of the ostrich and other birds are slender, curved, and rather feeble organs. in the archæopteryx, a fossil bird which agrees with the pterodactyles in retaining the separate condition of the metacarpal bones and in having the same number of phalanges in two of the fingers of the fore limb, the terminal claws are rather more compressed from side to side, and stronger than in the ostrich, but not nearly so strong as in the pterodactyle. the archæopteryx differs from the pterodactyle in having no trace of a wing finger. the first metacarpal bone is short, as in all birds; and the first phalange scarcely lengthens that segment of the first digit of the bird's hand to the same length as the other metacarpal bones. it therefore was not bent backward like the first digit in pterodactyles. the wing finger, from which the genius of cuvier selected the scientific name--pterodactyle--for these fossils, yields their most distinctive character. it is a feature which could only be partly paralleled in the bat, by making changes of structure which would remove every support to the wing but the outermost digit of that animal's hand. in the bat's hand the membrane for flight is extended chiefly by four diverging metacarpal bones. there are only two or three phalanges in each digit in its four wing fingers. in pterodactyles the metacarpal bones are, as we have seen, arranged in close contact, and take no part in stretching the wing. the wing finger in birds there is nothing whatever to represent the wing finger of the pterodactyle, for it is an organ external to the finger bones of the bird, and contains four phalanges. the first phalange is quite different from the others. its length is astonishing when compared with the small phalanges of the clawed fingers. the articular surface, which joins on to the wing metacarpal bone, is a concave articulation, which fits the pulley in which that bone ends. the pulley articulation admits of an extension movement in one direction only. many specimens show the wing finger to be folded up so as to extend backward. the whole finger is preserved in other specimens straightened out so as to be in line with the metacarpus. this condition is well seen in professor marsh's specimen of rhamphorhynchus, which has the wing membrane preserved, in which all bones of the fore-arm metacarpus and wing finger are extended in a continuous curve. the outer surface of the end of the first bone of the wing finger overlaps the wing metacarpal, so that a maximum of strength and resistance is provided in the bony structures by which the wing is supported. there is, therefore, in flight only one angular bend in the limb, and that is between the upper arm bone and the fore-arm. an immense pneumatic foramen is situate in a groove on the under side of the upper end of the first phalange in ornithocheirus, but is absent in specimens from the kimeridge clay. this bone is long and stout. it terminates at the lower end in an obliquely truncated articular surface. specimens occur in the cambridge greensand which are inches broad at the upper end and nearly - / inch wide at the lower end. an imperfect bone from the chalk is - / inches long. the bones are all flattened. specimens from the chalk of kansas at munich are inches long. the second phalange is concave at the upper articular end and convex in the longer direction at the lower end. the articular points of union between the several phalanges form prominences on the under side of the finger in consequence of the adjacent bones being a little widened at their junction. it should be mentioned that there is a proximal epiphysis or separate bone to the first phalange, adjacent to the pulley joint of the metacarpal bone, which is like the separate olecranon process of the ulna of the fore-arm. it sometimes comes away in specimens from the chalk and cambridge greensand, leaving a large circular pit with a depressed narrow border. on the outer side of this process is a rounded boss, which may possibly have supported the bone, if it were applied to the ground with the wing folded up, like the wing of a bat directed upward and backward at the animal's side. the four bones of the wing finger usually decrease progressively in length, so that in rhamphorhynchus, in which the length of the animal's head only slightly exceeds - / inches, the first phalange is nearly as long, the second phalange is about - / inches, the third - / inches, and the fourth a little over inches. thus the entire length of the four phalanges slightly exceeds inches, or rather more than three times the length of the head. but the fore-arm and metacarpus in this type only measure inches. therefore the entire spread of wings could not have been more than feet inches. the largest ornithosaur in which accurate measurements have been made is the toothless pterodactyle ornithostoma, also named pteranodon, from north america. in that type the head appears to have been about or feet long, and the wing finger exceeded feet; while the length of the fore-arm and metacarpus exceeded feet. the width of the body would not have been more than foot. the length of the short humerus, which was about inches, did not add greatly to the stretch of the wing; so that the spread of the wings as stretched in flight may be given as probably not exceeding or feet. a fine example of the wing bones of this animal quite as large has been obtained by the (british museum natural history). many years ago, on very fragmentary materials, i estimated the wings in the english cretaceous ornithocheirus as probably having a stretch of feet in the largest specimens, basing the calculation partly upon the extent of the longest wings in existing birds relatively to their bones, and partly upon the size of the largest associated bones which were then known. chapter xii evidences of the animal's habits from its remains such are the more remarkable characters of the bones in a type of animal life which was more anomalous than any other which peopled the earth in the secondary epoch of geological time. its skeleton in different parts resembles reptiles, birds, and mammals; with modifications and combinations so singular that they might have been deemed impossible if nature's power of varying the skeleton could be limited. since ornithosaurs were provided with wings, we may believe the animals to some extent to have resembled birds in habit. their modes of progression were more varied, for the structures indicate an equal capacity for movement on land as a biped, or as a quadruped, with movement in the air. there is little evidence to support the idea that they were usually aquatic animals. the majority of birds which frequent the water have their bodies stored with fat and the bones of their extremities filled with marrow. and a bird's marrow bones are stouter and stronger than those which are filled with air. there are few, if any, bones of pterodactyles so thick as to suggest the conclusion that they contained marrow, and the bones of the extremities appear to have been constructed on the lightest type found among terrestrial birds. their thinness, except in a few specimens from the wealden rocks, is marvellous; and all the later pterodactyles show the arrangement, as in birds, by which air from the lungs is conveyed to the principal bones. no pterodactyle has shown any trace of the web-footed condition seen in birds which swim on the water, unless the diverging bones of the hind foot in rhamphorhynchus supports that inference. the bones of the hind foot are relatively small, and if it were not that a bird stands easily upon one foot, might be considered scarcely adequate to support the animal in the position which terrestrial birds usually occupy. yet, as compared with the length and breadth of the foot in an ostrich, the toes of an ornithosaur are seen to be ample for support. these facts appear to discourage the idea that the animals were equally at home on land and water, and in air. some light may be thrown upon the animal's habits by the geological circumstances under which the remains are found. the pterodactyle named dimorphodon, from the lias of the south of england, is associated with evidences of terrestrial land animals, the best known of which is scelidosaurus, an armoured dinosaur adapted by its limbs for progression on land. and the pterodactyle campylognathus, from the lias of whitby, is associated with trunks of coniferous trees and remains of insects. so that the occurrence of pterodactyles in a marine stratum is not inconsistent with their having been transported by streams from off the old land surface of the lias, on which coniferous trees grew and dinosaurs lived. similar considerations apply to the occurrence of the rhamphocephalus in the stonesfield slate of england. the deposit is not only formed in shallow water, but contains terrestrial insects, a variety of land plants, and many reptiles and other animals which lived upon land. the specimens from the purbeck beds, again, are in strata which yield a multitude of the spoils of a nearly adjacent land surface; while the numerous remains found in the marine solenhofen slate in germany are similarly associated with abundant evidences of varied types of terrestrial life. the evidence grows in force from its cumulative character. the wealden beds, which yield many terrestrial reptiles and so much evidence of terrestrial vegetation, and shallow-water conditions of disposition, have afforded important pterodactyle remains from the isle of wight and sussex. the chief english deposit in which these fossils are found, the upper greensand, has afforded thousands of bones, battered and broken on a shore, where they have lain in little associated groups of remains, often becoming overgrown with small marine shells. side by side with them are found bones of true terrestrial lizards and crocodiles of the type of the gavial of the indian rivers, many terrestrial dinosaurs, and other evidences of land life, including fossil resins, such as are met with in the form of amber or copal at the present day. the great bones of pterodactyles found in the chalk of kent, near rochester, became entombed, beyond question, far from a land surface. there is nothing to show whether the animals died on land and were drifted out to sea like the timber which is found water-logged and sunken after being drilled by the ship-worm (teredo) of that epoch. seeing the power of flight which the animal possessed, storms may have struck down travellers from time to time, when far from land. evidence of habit of another kind may be found in their teeth. they are brightly enamelled, sharp, formidable; and are frequently long, overlapping the sides of the jaws. they are organs which are often better adapted for grasping than for tearing, as may be seen in the inclined teeth of rhamphocephalus of the stonesfield slate; and better adapted for killing than tearing, from their piercing forms and cutting edges, in genera like ornithocheirus of the greensand. the manner in which the teeth were implanted and carried is better paralleled by the fish-eating crocodile of indian rivers than by the flesh-eating crocodiles, or muggers, which live indifferently in rivers and the sea. as the kingfisher finds its food (see fig. ) from the surface of the water without being in the common sense of the term a water bird, so some pterodactyles may have fed on fish, for which their teeth are well adapted, both in the stream and by the shore. a pterodactyle's teeth vary a good deal in appearance. the few large teeth in the front of the jaw in dimorphodon, associated with the many small vertical teeth placed further backward, suggest that the taking of food may have been a process requiring leisure, since the hinder teeth adapted to mincing the animal's meat are extremely small. the way in which the teeth are shaped and arranged differs with the genera. in pterodactylus they are short and broad and few, placed for the most part towards the front of the jaws. their lancet-shaped form indicates a shear-like action adapted to dividing flesh. in the associated genus rhamphorhynchus the teeth are absent from the extremity of the jaw, are slender, pointed, spaced far apart, and extend far backward. when the jaws of the rhamphorhynchus are brought together there is always a gap between them in front, which has led to belief that the teeth were replaced by some kind of horny armature which has perished. in the long-nosed english type of ornithocheirus the jaws are compressed together, so that the teeth of the opposite sides are parallel to each other, with the margins well filled with teeth, which are never in close contact, though occasionally closer and larger in front, in some of the forms with thick truncated snouts. it is not the least interesting circumstance of the dentition of pterodactyles that, associated in the same deposits with these most recent genera with teeth powerfully developed, there is a genus named ornithostoma from the resemblance of its mouth to that of a bird in being entirely devoid of teeth. it is scarcely possible to distinguish the remains of the toothed and toothless skeletons except in the dentary character of the jaws. there is no evidence that the toothless types ever possessed a tooth of any sort. they were first found in fragments in england in the cambridge greensand, but were afterwards met with in great abundance in the chalk of kansas, where the same animals were named pteranodon. a jaw so entirely bird-like suggests that the digestive organs of pterodactyles may in such toothless forms at least have been characterised by a gizzard, which is so distinctive of birds. the absence of teeth in the great ant-eater and some other allied mammals has transferred the function which teeth usually perform to the stomach, one part of which becomes greatly thickened and muscular, adapting itself to the work which it has to perform. it is probable that the gizzard may be developed in relation to the necessities which food creates, since even trout, feeding on the shell-fish in some irish lochs, acquire such a thickened muscular stomach, and a like modification is recorded in other fishes as produced by food. closely connected with an animal's habits is the protection to the body which is afforded by the skin. in pterodactyles the evidence of the condition of the skin is scanty, and mostly negative. sometimes the dense, smooth texture of the jaw bones indicates a covering like the skin of a lizard or the hinder part of the jaw of a bird. some jaws from the cambridge greensand have the bone channeled over its surface by minute blood vessels which have impressed themselves into the bone more easily than into its covering. thus in the species of ornithocheirus distinguished as _microdon_ the palate is absolutely smooth, while in the species named _machærorhynchus_ it is marked by parallel impressed vascular grooves which diverge from the median line. this condition clearly indicates a difference in the covering of the bone, and that in the latter species the covering had fewer blood vessels and more horny protection than in the other. the tissue may not have been of firmer consistence than in the palate of mammals. the extremity of the beak is often as full of blood vessels as the jaw of a turtle or crocodile. covering of the body there is no trace even in specimens from the solenhofen or stonesfield slate of any covering to the body. there are no specimens preserved like mummies, and although the substance of the wings is found there is no trace of fur or feathers, bones, or scales on the skin. the only example in which there is even an appearance suggesting feathers is in the beautiful scaphognathus at bonn, and upon portions of the wing membrane of that specimen are preserved a very few small short and apparently tubular bodies, which have a suggestive resemblance to the quills of small undeveloped feathers. such evidences have been diligently sought for. professor marsh, after examining the wing membranes of his specimen of rhamphorhynchus from solenhofen, stated that the wings were partially folded and naturally contracted into folds, and that the surface of the tissue is marked by delicate striæ, which might easily be taken at first sight for a thin coating of hair. closer investigation proved the markings to be minute wrinkles on the under surface of the wing membrane. this negative evidence has considerable value, because the solenhofen slate has preserved in the two known examples of the bird archæopteryx beautiful details of the structure of the larger feathers concerned in flight. it has preserved many structures far more delicate. there is, therefore, reason for believing that if the skin had possessed any covering like one of those found in existing vertebrate animals, it could scarcely have escaped detection in the numerous undisturbed skeletons of pterodactyles which have been examined. the absence of a recognisable covering to the skin in a fossil state cannot be accepted as conclusive evidence of the temperature, habits, or affinities of the animal. although mammalia are almost entirely clothed with dense hair, which has never been found in a recognisable condition in a fossil state in any specimen of tertiary age, one entire order, the cetacea, show in the smooth hairless skins of whales and porpoises that the class may part with the typical characteristic covering without loss of temperature and without intelligible cause. that the absence of hair is not due to the aquatic conditions of rivers or sea is proved by other marine mammals, like seals, having the skin clothed with a dense growth of hair, which is not surpassed in any other order. the fineness of the growth of hair in man gives a superficial appearance of the skin being imperfectly clothed, and a similar skin in a fossil state might give the impression that it was devoid of hair. there are many mammals in which the skin is scantily clothed with hair as the animal grows old. neither the elephant nor the armadillo in a fossil state would be likely to have the hair preserved, for the growth is thin on the bony shields of the living armadilloes. yet the difficulty need be no more inherent in the nature of hair than in that of feathers, since the hair of the mammoth and rhinoceros has been completely preserved upon their skins in the tundras of siberia, densely clothing the body. this may go to show that the pterodactyle possessed a thin covering of hair, or, more probably, that hair was absent. since reptiles are equally variable in the clothing of the skin with bony or horny plates, and in sometimes having no such protection, it may not appear singular that the skin in ornithosaurs has hitherto given no evidence of a covering. from analogy a covering might have been expected; feathers of birds and hair of mammals are non-conducting coverings suited to arrest the loss of heat. with the evidence, such as it is, of resemblance of ornithosaurs to birds in some features of respiration and flight, a covering to the skin might have been expected. yet the covering may not be necessary to a high temperature of the blood. since dr. john davy made his observations it has been known that the temperature of the tunny, above ° fahrenheit, is as warm as the african scaly ant-eater named the pangolin, which has the body more amply protected by its covering. this illustration also shows that hot blood may be produced without a four-celled heart, with which it is usually associated, and that even if the skin in pterodactyles was absolutely naked an active life and an abundant supply of blood could have given the animal a high temperature. the circumstance that in several individuals the substance of the wing membrane is preserved would appear to indicate either that it was exceptionally stout when there would have been small chance of resisting decomposition, or that its preservation is due to a covering which once existed of fur or down or other clothing substance, which has proved more durable than the skin itself. [illustration: fig. . remains of dimorphodon from the lias of lyme regis showing the skull, neck, back and some of the longer bones of the skeleton _from a slab in the british museum (natural history)_] chapter xiii ancient ornithosaurs from the lias cuvier's discourse on the revolutions of the earth made the pterodactyle known to english readers early in the nineteenth century. dr. buckland, the distinguished professor of geology at oxford, discovered in a far larger specimen in the lias of lyme regis, and it became known by a figure published by the geological society, and by the description in his famous bridgewater treatise, p. . this animal was tantalising in imperfect preservation. the bones were scattered in the clay, so as to give no idea of the animal's aspect. knowledge of its limbs and body has been gradually acquired; and now, for some years, the tail and most parts of the skeleton have been well known in this oldest and most interesting british pterodactyle. sir richard owen after some time separated the fossil as a distinct genus, named dimorphodon; for it was in many ways unlike the pterodactyles described from bavaria. the name dimorphodon indicated the two distinct kinds of teeth in the jaws, a character which is still unparalleled among pterodactyles of newer age. there are a few large pointed, piercing and tearing teeth in the front of the jaws, with smaller teeth further back, placed among the tearing teeth in the upper jaw; while in the lower jaw the small teeth are continuous, close-set, and form a fine cutting edge like a saw. [illustration: fig. . left side of dimorphodon (restored) at rest] the dimorphodon has a short beak, a deep head, and deep lower jaw, which is overlapped by the cheek bones. the side of the head is occupied by four vacuities, separated by narrow bars of bone. first, in front, is the immense opening for the nostril, triangular in form, with the long upper side following the rounded curve of the face. a large triangular opening intervenes between the nose hole and the eye hole, scarcely smaller than the former, but much larger than the orbit of the eye. the eye hole is shaped like a kite or inverted pear. further back still is a narrower vertical opening known as the lateral or inferior temporal vacuity. the back of the head is badly preserved. the two principal skulls differ in depth, probably from the strains under which they were pressed flat in the clay. a singular detail of structure is found in the extremity of the lower jaw, which is turned slightly downward, and terminates in a short toothless point. the head of dimorphodon is about eight inches long. [illustration: fig. . dimorphodon macronyx restored form of the animal] the neck bones are of suitable stoutness and width to support the head. the bones are yoked together by strong processes. the neck was about inches long, did not include more than seven bones, and appeared short owing only to the depth and size of the head. the length of the backbone which supported the ribs was also about inches. its joints are remarkably short when compared with those of the neck. the tail is about inches long. the extreme length of the animal from the tip of the nose to the end of the tail may have been feet inches, supposing it to have walked on all fours in the manner of a reptile or mammal. this may have been a common position, but dimorphodon may probably also have been a biped. before , when the first restoration appeared in the _illustrated london news_, the legs had been regarded as too short to have supported the animal, standing upon its hind limbs. they are here seen to be well adapted for such a purpose. the upper leg bone is - / inches long, the lower leg bone is - / inches long, and the singularly strong instep bones are firmly packed together side by side as in a leaping or jumping mammal, and measure - / inches in length. dimorphodon differs from several other pterodactyles in having the hind limb provided with a fifth outermost short instep bone, to which two toe bones are attached. these bones are elongated in a way that may be compared, on a small scale, with the elongation of the wing finger in the fore limb. the digit was manifestly used in the same way as the wing finger, in partial support of a flying membrane, though its direction may have been upward and outward, rather than inward. there is no evidence of a pulley joint between the metatarsal and the adjacent phalange. the height of the dimorphodon, standing on its hind legs in the position of a bird, with the wings folded upon the body in the manner of a bird, was about inches. an ungainly, ill-balanced animal in aspect, but not more so than many big-headed birds, and probably capable of resting upon the instep bones as many birds do. the chief point of variation from the pterodactyle wing is in the relative length of the metacarpus in dimorphodon. it is shorter than the other bones in the wing, never exceeding - / inches. the total length of all the arm bones down to the point where the metacarpus might have touched the ground, or where the wing finger is bent upon it, is about inches, which gives a length of less than inches below the upper arm bone. the four bones of the wing finger measure, from the point where the first bone bends upon the metacarpus, less than inches. so that the wings could only have been carried in the manner of the wings of a bat, folded at the side and directed obliquely over the back when the animal moved on all fours. its body would appear to have been raised high above the ground, in a manner almost unparalleled in reptiles, and comparable to birds and mammals. dimorphodon is to be imagined in full flight, with the body extended like that of a bird, when the wings would have had a spread from side to side of about feet inches. as in other animals of this group, the three claws on the front feet are larger than the similar four claws on the hind feet; as though the fingers might have functions in grasping prey, which were not shared by the toes. [illustration: fig. . dimorphodon macronyx walking as a quadruped restoration of the skeleton] the restorations give faithful pictures of the skeleton, and the form of the body is built upon the indications of muscular structure seen in the bones. a second english pterodactyle is found in the upper lias of whitby. it is only known from an imperfect skull, published in . it has the great advantage of preserving the bones in their natural relations to each other, and with a length of head probably similar to dimorphodon shows that the depth at the back of the eye was much less; and the skull wants the arched contour of face seen in dimorphodon. the head has the same four lateral vacuities, but the nostril is relatively small and elongated, extending partly above the oval antorbital opening, which was larger. there is thus a difference of proportion, but it is precisely such as might result from the species having the skull flatter. the head is easily distinguished by the small nostril, which is smaller than the orbit of the eye. the animal is referred to another genus. the quadrate bones which give attachment to the lower jaw send a process inward to meet the bones of the palate, which differ somewhat from the usual condition. two bony rods extend from the quadrate bones backward and upward to the sphenoid, and two more slender bones extend from the quadrate bones forward, and converge in a #v#-shape, to define the division between the openings of the nostrils on the palate. the #v#-shaped bone in front is called the vomer, while the hinder part is called pterygoid. the bones that extend backward to the sphenoid are not easily identified. this animal is one of the most interesting of pterodactyles from the very reptilian character exhibited in the back of the head, which appears to be different from other specimens, which are more like a bird in that region. yet underneath this reptilian aspect, with the bony bar at the side of the temporal region of the head formed by the squamosal and quadrate bones, defining the two temporal vacuities as in reptiles, a mould is preserved of the cavity once occupied by the brain, showing the chief details of structure of that organ, and proving that in so far as it departs from the brain of a bird it appears to resemble the brain of a mammal, and is unlike the brain of a reptile. the pterodactyles from the lias of germany are similar to the english types, in so far as they can be compared. in i had the opportunity of studying those which were preserved in the castle at banz, which professor andreas wagner, in , referred to the new genus dorygnathus. the skull is unknown, but the lower jaw, - / inches long, is less than - / inches wide at the articulation with the quadrate bone in the skull. the depth of the lower jaw does not exceed / inch, so that it is in marked contrast to buckland's dimorphodon. the symphysis, which completely blends the rami of the jaw, is short. as far as it extends it contains large tearing teeth, followed by smaller teeth behind, like those of dimorphodon. but this german fossil appears to differ from the english type in having the front of the lower jaw, for about / inch, compressed from side to side into a sharp blade or spear, more marked than in any other pterodactyle, and directed _upward_ instead of downward as in dimorphodon. nearly all the measurements in the skeleton are practically identical with those of the english dimorphodon, and extend to the jaw, humerus, ulna and radius, wing metacarpal, first phalange of the wing finger. the principal bones of the hind limb appear to be a little shorter; but the scapula and coracoid are slightly larger. all these bones are so similar in form to dimorphodon that they could not be separated from the lyme regis species, if they were found in the same locality. [illustration: fig. . dimorphodon macronyx walking as a biped _based chiefly on remains in the british museum_] [illustration: fig. . lower jaw of dorygnathus seen from below from the lower lias of germany, showing the spear in front of the tooth sockets] just as the upper lias in england has yielded a second pterodactyle, so the upper lias in germany has yielded a skeleton, to which felix plieninger, in , gave the name campylognathus. it is an instructive skeleton, with the head much smaller than in dimorphodon, being less than inches long, but, unfortunately, broken and disturbed. a lower jaw gives the length - / inches. like the other pterodactyles from the lias, it has the extremity of the beak toothless, with larger teeth in the region of the symphysis in front and smaller teeth behind. the jaw is deeper than in the banz specimen from the lower lias, but not so deep as in dimorphodon. the teeth of the upper jaw vary in size, and there appears to be an exceptionally large tooth in the position of the mammalian canine at the junction of the bones named maxillary and intermaxillary. the nasal opening is small and elongated, as in the english specimen from whitby. as in that type there is little or no indication of the convex contour of the face seen in dimorphodon. the neck does not appear to be preserved. in the back the vertebræ are about / inch long, so that twelve, which is the usual number, would only occupy a length of a little more than - / inches. the tail is elongated like that of dimorphodon, and bordered in the same way by ossified ligaments. there are thirty-five tail vertebræ. those which immediately follow the pelvis are short, like the vertebræ of the back. but they soon elongate, and reach a maximum length of nearly - / inches at the eighth, and then gradually diminish till the last scarcely exceeds / inch in length. the length of the tail is about inches; this appears to be an inch or two longer than in dimorphodon. the longest rib measures - / inches, and the shortest inches. these ribs probably were connected with the sternum, which is imperfectly preserved. [illustration: fig. . dimorphodon macronyx showing the maximum spread of the wing membranes] the bones of the limbs have about the same length as those of dimorphodon, so far as they can be compared, except that the ulna and radius are shorter. the wing metacarpal is of about the same length, but the first phalange of the wing finger measures - / inches, the second is about - / inches, the third - / inches, and the fourth - / inches; so that the total length of the wing finger was about half an inch short of feet. one character especially deserves attention in the apparent successive elongation of the first three phalanges in the wing finger in dimorphodon. the third phalange is the longest in the only specimen in which the finger bones are all preserved. usually the first phalange is much longer than the second, so that it is a further point of interest to find that this german type shares with dimorphodon a character of the wing finger which distinguishes both from some members of the group by its short first phalange. [illustration: fig. . the left side of the pelvis of dimorphodon showing the two prepubic bones] the pelvis is exceptionally strong in campylognathus, and although it is crushed the bones manifestly met at the base of the ischium, while the pubic bones were separated from each other in front. the bones of the hind limb are altogether shorter in the german fossil than in dimorphodon, especially in the tibia; but the structure of the metatarsus is just the same, even to the short fifth metatarsal with its two digits, only those bones are extremely short, instead of being elongated as in dimorphodon. it is therefore convenient, from the different proportions of the body, that campylognathus may be separated from dimorphodon; but so much as is preserved of the english specimen from the upper lias of whitby rather favours the belief that our species should also be referred to campylognathus, which had not been figured when the whitby skull was referred to scaphognathus by mr. newton. it may be doubtful whether there is sufficient evidence to establish the distinctness of the other german genus dorygnathus, though it may be retained pending further knowledge. in these characters are grounds for placing the lias pterodactyles in a distinct family, the dimorphodontidæ, as was suggested in . this evidence is found in the five metatarsal bones, of which four are in close contact, the middle two being slightly the longest, so as to present the general aspect of the corresponding bones in a mammal rather than a bird. secondly, the very slender fibula, prolonged down the length of the shin bone, which ends in a rounded pulley like the corresponding bone of a bird. thirdly, the great elongation of the third wing phalange. fourthly, the prolongation of the coracoid bone beyond the articulation for the humerus, as in a bird. and the toothless, spear-shaped beak, and jaw with large teeth in front and small teeth behind, are also distinctive characters. chapter xiv ornithosaurs from the middle secondary rocks rhamphocephalus the stonesfield slate in england, which corresponds in age with the lower part of the great or bath oolite, yields many evidences of terrestrial life--land plants, insects, and mammals--preserved in a marine deposit. a number of isolated bones have been found of pterodactyles, some of them indicating animals of considerable size and strength. the nature of the limestone was unfavourable to the preservation of soft wing membranes, or even to the bones remaining in natural association. very little is known of the head of rhamphocephalus. one imperfect specimen shows a long temporal region which is wide, and a very narrow interspace between the orbits; with a long face, indicated by the extension of narrow nasal bones. the lower jaw has an edentulous beak or spear in front, which is compressed from side to side in the manner of the liassic forms, but turned upward slightly, as in dorygnathus or campylognathus. behind this extremity are sharp, tall teeth, few in number, which somewhat diminish in size as they extend backward, and do not suddenly change to smaller series, as in the lias genera. a few small vertebræ have been found, indicating the neck and back. the sacrum consists of five vertebræ. one small example has a length of only an inch. it is a little narrower behind than in front, and would be consistent with the animal having had a long tail, which i believe to have been present, although i have not seen any caudal vertebræ. the early ribs are like the early ribs of a crocodile or bird in the well-marked double articulation. the later ribs appear to have but one head. #v#-shaped abdominal ribs are preserved. much of the animal is unknown. the coracoid seems to have been directed forward, and, as in a bird, it is - / inches long. the humerus is - / inches long, and the fore-arm measured inches, so that it was relatively longer than in dimorphodon. the metacarpus is - / inches long. the wing finger was exceptionally long and strong. professor huxley gave its length at inches. my own studies lead to the conclusion that the first finger bone of the wing was the shorter, and that although they did not differ greatly in length, the second was probably the longest, as in campylognathus. professor huxley makes the second and third phalanges - / inches long, and the first only about / inch shorter, while the fourth phalange is - / inches. these measurements are based upon some specimens in the oxford university museum. there is only one first phalange which has a length of - / inches. the others are between and inches, or but little exceed inches; so that as all the fourth phalanges which are known have a length of - / inches, it is possible that the normal length of the first phalange in the larger species was - / inches. the largest of the phalanges which may be classed as second or third is - / inches, and that, i suppose, may have been associated with the - / inches first phalange. but the other bones which could have had this position all measure - / and - / inches. the three species indicated by finger bones may have had the measurements:-- phalanges of the wing finger ________________/\________________ | | i. ii. iii. iv. - / - / [ ?] - / } length of each bone - / - / - / [ - / ?] } in inches. - / ---- ---- ---- } the femur is represented by many examples--one - / inches long, and others less than inches long ( - / ). in campylognathus, which has so much in common with the jaw and the wing bones in size, the upper leg bone is - / inches. therefore if we assign the larger femur to the larger wing, the femur will be relatively longer in all species of rhamphocephalus than in campylognathus. only one example of a tibia is preserved. it is - / inches long, or only / inch shorter than the bone in campylognathus, which has the femur - / inches, so that i refer the tibia of rhamphocephalus to the species which has the intermediate length of wing. these coincidences with campylognathus establish a close affinity, and may raise the question whether the upper lias species may not be included in the stonesfield slate genus rhamphocephalus. the late professor phillips, in his _geology of oxford_, attempted a restoration of the stonesfield ornithosaur, and produced a picturesque effect (p. ); but no restoration is possible without such attention to the proportions of the bones as we have indicated. oxford clay a few bones of flying reptiles have been found in the lower oxford clay near peterborough, and others in the upper oxford clay at st. ives, in huntingdonshire. a single tail vertebra from the middle oxford clay, near oxford, long since came under my own notice, and shows that these animals belong to a long-tailed type like campylognathus. the cervical vertebræ are remarkable for being scarcely longer than the dorsal vertebræ; and the dorsal are at least half as long again as is usual, having rather the proportion of bones in the back of a crocodile. lithographic slate long-tailed pterodactyles are beautifully preserved in the lithographic limestone of the south of bavaria, at solenhofen, and the quarries in its neighbourhood, often with the skeleton or a large part of it flattened out in the plane of bedding of the rock. fine skeletons are preserved in the superb museum at munich, at heidelberg, bonn, haarlem, and london, and are all referred to the genus rhamphorhynchus or to scaphognathus. it is a type with powerfully developed wings and a long, stiff tail, very similar to that of dimorphodon, so that some naturalists refer both to the same family. there is some resemblance. the type which is most like dimorphodon is the celebrated fossil at bonn, sometimes called _pterodactylus crassirostris_, which in a restored form, with a short tail, has been reproduced in many text-books. no tail is preserved in the slab, and i ventured to give the animal a tail for the first time in a restoration (p. ) published by the _illustrated london news_ in , which accompanied a report of a royal institution lecture. afterwards, in , professor zittel, of munich, published the same conclusion. the reason for restoring the tail was that the animal had the head constructed in the same way as pterodactyles with a long tail, and showed differences from types in which the tail is short; and there is no known short-tailed pterodactyle, with wrist and hand bones, such as characterise this animal. the side of the face has a general resemblance to the pterodactyles from the lias, for although the framework is firmer, the four apertures in the head are similarly placed. the nostril is rather small and elongated, and ascends over the larger antorbital vacuity. the orbit for the eye is the largest opening in the head, so that these three apertures successively increase in size, and are followed by the vertically elongated post-orbital vacuity. the teeth are widely spaced apart, and those in the skull extend some distance backward to the end of the maxillary bone. there are few teeth in the lower jaw, and they correspond to the large anterior teeth of dimorphodon, there being no teeth behind the nasal opening. the lower jaw is straight, and the extremities of the jaws met when the mouth was closed. the breast bone does not show the keel which is so remarkable in rhamphorhynchus, which may be attributed to its under side being exposed, so as to exhibit the pneumatic foramina. the ribs have double heads, more like those of a crocodile in the region of the back than is the case with the bird-like ribs from stonesfield. the second joint in the wing finger may be longer than the first--a character which would tend to the association of this pterodactyle with species from the lias; a relation to which attention was first drawn by mr. e. t. newton, who described the whitby skull. the pterodactyles from the solenhofen slate which possess long tails have a series of characters which show affinity with the other long-tailed types. the jaws are much more slender. the orbit of the eye in rhamphorhynchus is enormously large, and placed vertically above the articulation for the lower jaw. immediately in front of the eye are two small and elongated openings, the hinder of which, known as the antorbital vacuity, is often slightly smaller than the nostril, which is placed in the middle length of the head, or a little further back, giving a long dagger-shaped jaw, which terminates in a toothless spear. the lower jaw has a corresponding sharp extremity. the teeth are directed forward in a way that is quite exceptional. notwithstanding the massiveness and elongation of the neck vertebræ, which are nearly twice as long as those of the back, the neck is sometimes only about half the length of the skull. all these long-tailed species from the lithographic stone agree in having the sternum broad, with a long strong keel, extending far forward. the coracoid bones extend outward like those of a crocodile, so as to widen the chest cavity instead of being carried forward as the bones are in birds. these bones in this animal were attached to the anterior extremity of the sternum, so that the keel extended in advance of the articulation as in other pterodactyles. the breadth of the sternum shows that, as in mammals, the fore part of the body must have been fully twice the width of the region of the hip-girdle, where the slenderer hind limbs were attached. the length of the fore limb was enormous, for although the head suggests an immense length relatively to the body, nearly equal to neck and back together, the head is not more than a third of the length of the wing bones. the wing bones are remarkable for the short powerful humerus with an expanded radial crest, which is fully equal in width to half the length of the bone. another character is the extreme shortness of the metacarpus, usually associated with immense strength of the wing metacarpal bone. the hind limbs are relatively small and relatively short. the femur is usually shorter than the humerus, and the tibia is much shorter than the ulna. the bones of the instep, instead of being held together firmly as in the lias genera, diverge from each other, widening out, though it often happens that four of the five metatarsals differ but little in length. the fifth digit is always shorter. the hip-girdle of bones differs chiefly from other types in the way in which those bones, which have sometimes been likened to the marsupial bones, are conditioned. they may be a pair of triangular bones which meet in the middle line, so that there is an outer angle like the arm of a capital y. sometimes these triangular bones are blended into a curved, bow-shaped arch, which in several specimens appears to extend forward from near the place of articulation of the femur. this is seen in fossil skeletons at heidelberg and munich. it is possible that this position is an accident of preservation, and that the prepubic bones are really attached to the lower border of the pubic bones. immense as the length of the tail appears to be, exceeding the skull and remainder of the vertebral column, it falls far short of the combined length of the phalanges of the wing finger. the power of flight was manifestly greater in rhamphorhynchus than in other members of the group, and all the modifications of the skeleton tend towards adaptation of the animals for flying. the most remarkable modification of structure at the extremity of the tail was made known by professor marsh in a vertical, leaf-like expansion in this genus, which had not previously been observed (p. ). the vertebræ go on steadily diminishing in length in the usual way, and then the ossified structures which bordered the tail bones and run parallel with the vertebræ in all the rhamphorhynchus family, suddenly diverge downward and upward at right angles to the vertebræ, forming a vertical crest above and a corresponding keel below; and between these structures, which are identified with the neural spines and chevron bones of ordinary vertebræ, the membrane extends, giving the extremity of the tail a rudder-like feature, which, from knowledge of the construction of the tail of a child's kite, may well be thought to have had influence in directing and steadying the animal's movements. there are many minor features in the shoulder-girdle, which show that the coracoid, for example, was becoming unlike that bone in the lias, though it still continues to have a bony union with the elongated shoulder-blade of the back. [illustration: fig. . restoration of the skeleton of _rhamphorhynchus phyllurus_ from the solenhofen slate, partly based upon the skeleton with the wing membranes preserved] [illustration: fig. . restoration of the skeleton of _scaphognathus crassirostris_ published in the _illustrated london news_ in . in which a tail is shown on the evidence of the structure of the head and hand] [illustration: fig. . six restorations . ramphocephalus. stonesfield slate. john phillips, . rhamphorhynchus. o. c. marsh, . rhamphorhynchus. v. zittel, . ornithostoma. williston, . dimorphodon. buckland, . tail then unknown . ornithocheirus. h. g. seeley, ] the great german delineator of these animals, von meyer, admitted six different species. mr. newton and mr. lydekker diminish the number to four. it is not easy to determine these differences, or to say how far the differences observed in the bones characterise species or genera. it is certain that there is one remarkable difference from other and older pterodactyles, in that the last or fourth bone in the wing finger is usually slightly longer than the third bone, which precedes it. there is a certain variability in the specimens which makes discussion of their characters difficult, and has led to some forms being regarded as varieties, while others, of which less material is available, are classed as species. i am disposed to say that some of the confusion may have resulted from specimens being wrongly named. thus, there is a rhamphorhynchus called curtimanus, or the form with the short hand. it is represented by two types. one of these appears to have the humerus short, the ulna and radius long, and the finger bones long; the other has the humerus longer, the ulna much shorter, and the finger bones shorter. they are clearly different species, but the second variety agrees in almost every detail with a species named hirundinaceus, the swallow-like rhamphorhynchus. this identification shows, not that the latter is a bad species, but that curtimanus is a distinct species which had sometimes been confounded with the other. while most of these specimens show a small but steady decrease in the length of the several wing finger bones, the species called gemmingi has the first three bones absolutely equal and shorter than in the species curtimanus, longimanus, or hirundinaceus. in the same way, on the evidence of facts, i find myself unable to join in discarding professor marsh's species phyllurus, on account of the different proportions of its limb bones. the humerus, metacarpus, and third phalange of the wing finger in _rhamphorhynchus phyllurus_ are exceptionally short as compared with other species. everyone agrees that the species called longicaudus is a distinct one, so that it is chiefly in slight differences in the proportions of constituent parts of the skeleton that the types of the rhamphorhynchus are distinguished from each other. i cannot quite concur with either professor zittel (fig. , ) or professor marsh (fig. , ) in the expansion which they give to the wing membrane in their restorations; for although professor zittel represents the tail as free from the hind legs, while professor marsh connects them together, they both concur in carrying the wing membrane from the tip of the wing finger down to the extremity of the ankle joint. i should have preferred to carry it no further down the body than the lower part of the back, there being no fossil evidence in favour of this extension so far as specimens have been described. neither the membranous wings figured by zittel nor by marsh would warrant so much body membrane as the rhamphorhynchus has been credited with. i have based my restoration (p. ) of the skeleton chiefly on _rhamphorhynchus phyllurus._ the short-tailed types the pterodactylia are less variable; and the variation among the species is chiefly confined to relative length of the head, length of the neck, and the height of the body above the ground. the tail is always so short as to be inappreciable. many of the specimens are fragmentary, and the characters of the group are not easily determined without careful comparisons and measurements. the bones of the fore limb and wing finger are less stout than in the rhamphorhynchus type, while the femur is generally a little longer than the humerus, and the wing finger is short in comparison with its condition in rhamphorhynchus. these short-tailed pterodactyles give the impression of being active little animals, having very much the aspect of birds, upon four legs or two. the neck is about as long as the lower jaw, the antorbital vacuity in the head is imperfectly separated from the much larger nasal opening, the orbit of the eye is large and far back, the teeth are entirely in front of the nasal aperture, and the post-orbital vacuity is minute and inconspicuous. the sternum is much wider than long, and no specimens give evidence of a manubrium. the finger bones progressively decrease in length. the prepubic bones have a partially expanded fan-like form, and never show the triradiate shape, and are never anchylosed. about fifteen different kinds of pterodactyles have been described from the solenhofen slate, mostly referred to the genus pterodactylus, which comprises forms with a large head and long snout. some have been placed in a genus (ornithocephalus, or ptenodracon) in which the head is relatively short. the majority of the species are relatively small. the skull in _ornithocephalus brevirostris_ is only inch long, and the animal could not have stood more than - / inches to its back standing on all fours, and but little over - / inches standing as a biped, on the hind limbs. a restoration of the species called _pterodactylus scolopaciceps_, published in in the _illustrated london news_ in the position of a quadruped, shows an animal a little larger, with a body - / inches high and to inches long, with the wing finger - / inches long. larger animals occur in the same deposit, and in one named _pterodactylus grandis_ the leg bones are a foot long; and such an animal may have been nearly a foot in height to its back, standing as a quadruped, though most of these animals had the neck flexible and capable of being raised like the neck of a goose or a deer (p. ), and bent down like a duck's when feeding. [illustration: fig. . restoration of the skeleton of _ptenodracon brevirostris_ from the solenhofen slate. the fourth joint of the wing finger appears to be lost and has not been restored in the figure. (natural size)] the type of the genus pterodactylus is the form originally described by cuvier as_ pterodactylus longirostris_ (p. ). it is also known as _p. antiquus_, that name having been given by a german naturalist after cuvier had invented the genus, and before he had named the species. there are some remarkable features in which cuvier's animal is distinct from others which have been referred to the same genus. thus the head is - / inches long, while the entire length of the backbone to the extremity of the tail is only - / inches, and one vertebra in the neck is at least as long as six in the back, so that the animal has the greater part of its length in the head and neck, although the neck includes so few vertebræ. nearly all the teeth--which are few in number, short and broad, not exceeding a dozen in either jaw--are limited to the front part of the beak, and do not extend anywhere near the nasal vacuity. this is not the case with all. in the species named _p. kochi_, which i have regarded as the type of a distinct genus, there are large teeth in the front of the jaw corresponding to those of pterodactylus, and behind these a smaller series of teeth extending back under the nostril, which approaches close to the orbit of the eye, without any indication of a separate antorbital vacuity. on those characters the genus diopecephalus was defined. it is closely allied to pterodactylus; both agree in having the ilium prolonged forward more than twice as far as it is carried backward, the anterior process covering about half a dozen vertebræ, as in _pterodactylus longirostris_. a great many different types have been referred to _pterodactylus kochi_, and it is probable that they may eventually be distinguished from each other. the species in which the upper borders of the orbits approximate could be separated from those in which the frontal interspace is wider. [illustration: fig. . cycnorhamphus suevicus from the solenhofen slate showing the scattered position of the bones _original in the museum at tübingen_] [illustration: fig. . cycnorhamphus suevicus restoration showing the form of the body and the wing membranes] it is a remarkable feature in these animals that the middle bones of the foot, termed instep bones or metatarsals, are usually close together, so that the toes diverge from a narrow breadth, as in _p. longirostris_, _p. kochi_, and other forms; but there also appear to be splay-footed groups of pterodactyles like the species which have been named _p. elegans_ and _p. micronyx_, in which the metatarsus widens out so that the bones of the toes do not diverge, and that condition characterises the ptenodracon (_pterodactylus brevirostris_), to which genus these species may possibly be referred. nearly all who have studied these animals regard the singularly short-nosed species _p. brevirostris_ as forming a separate genus. for that genus sömmerring's descriptive name ornithocephalus, which he used for pterodactyles generally, might perhaps have been retained. but the name ptenodracon, suggested by mr. lydekker, has been used for these types. [illustration: fig. . _cycnorhamphus suevicus_ skeleton restored from the bones in fig. ] [illustration: fig. . restoration of skeleton cycnorhamphus fraasi showing the limbs on the right side _from a specimen in the museum at stuttgart_] [illustration: fig. . cycnorhamphus fraasi restoration of the form of the body] some of the largest specimens preserved at stuttgart and tübingen have been named _pterodactylus suevicus_ and _p. fraasii_. they do not approach the species _p. grandis_ in size, so far as can be judged from the fragmentary remains figured by von meyer; for what appears to be the third phalange of the wing finger is - / inches long, while in these species it is less than half that length, indicating an enormous development of wing, relatively to the length of the hind limb, which would probably refer the species to another genus. _pterodactylus suevicus_ differs from the typical pterodactyles in having a rounded, flattened under surface to the lower jaw, instead of the common condition of a sharp keel in the region of the symphysis. the beak also seems flattened and swan-like, and the teeth are limited to the front of the jaw. there appear to be some indications of small nostrils, which look upward like the nostrils of rhamphorhynchus, but this may be a deceptive appearance, and the nostrils are large lateral vacuities, which are in the position of antorbital vacuities, so that there would appear to be only two vacuities in the side of the head in these animals. the distinctive character of the skeleton in this genus is found in the extraordinary length of the metacarpus and in the complete ossification of the smaller metacarpal bones throughout their length. the metacarpal bones are much longer than the bones of the fore-arm, and about twice the length of the humerus. the first wing phalange is much longer than the others, which successively and rapidly diminish in length, so that the third is half the length of the first. there are differences in the pelvis; for the anterior process of the ilium is very short, in comparison with its length in the genus pterodactylus. and the long stalk of the prepubic bone with its great hammer-headed expansion transversely in front gives those bones a character unlike other genera, so that cycnorhamphus ranks as a good genus, easily distinguished from cuvier's type, in which the four bones of the wing are more equal in length, and the last is more than half the length of the first; while the metacarpus in that genus is only a little longer than the humerus, and much shorter than the ulna. the _pterodactylus suevicus_ has the neck vertebræ flat on the under side, and relatively short as compared with the more slender and narrower vertebræ of _p. fraasii_. chapter xv ornithosaurs from the upper secondary rocks when staying at swanage, in dorsetshire, many years ago, i had the rare good fortune to obtain from the purbeck beds the jaw of a pterodactyle, which had much in common in plan with the _cycnorhamphus fraasii_ from the lithographic slate, which is preserved at stuttgart. the tooth-bearing part of this lower jaw is inches long as preserved, extending back inches beyond the symphysis portion in which the two sides are blended together. it is different from professor fraas's specimen in having the teeth carried much further back, and in the animal being nearly twice as large. this fragment of the jaw is little more than foot long, which is probably less than half its original length. a vertebra nearly inches long, which is more than twice the length of the longest neck bones in the stuttgart fossil, is the only indication of the vertebral column. professor owen described a wing finger bone from these purbeck beds, which is nearly foot long. he terms it the second of the finger. it may be the third, and on the hypothesis that the animal had the proportions of the solenhofen fossil just referred to, the first wing finger bone of the english purbeck pterodactyle would have exceeded feet in length, and would give a length for the wing finger of about feet inches. for this animal the name doratorhynchus was suggested, but at present i am unable to distinguish it satisfactorily from cycnorhamphus, which it resembles in the forms both of the neck bones and of the jaw. very small pterodactyles are also found in the english purbeck strata, but the remains are few, and scattered, like these larger bones. [illustration: fig. . the longest known neck vertebra from the purbeck beds of swanage. (half natural size)] ornithodesmus latidens [illustration: fig. . cervical vertebra of ornithodesmus from the wealden beds of the isle of wight] the wealden strata being shallow, fresh-water deposits might have been expected to supply better knowledge of pterodactyles than has hitherto been available. jaws of ornithocheirus sagittirostris have been found in the beds at hastings, and in other parts of sussex. some fragments are as large as anything known. the best-preserved remains have come from the isle of wight, and were rewards to the enthusiastic search of the rev. w. fox, of brixton. in the principal specimen the teeth were short and wide, the head large and deep with large vacuities, but the small brain case of that skull is bird-like. the neck bones are - / inches long. in the upper part of the back the bones are united together by anchylosis, so that they form a structure in the back like a sacrum, which does not give attachment to the scapula, as in some pterodactyles from the chalk, but the bones are simply blended, as in the frigate-bird, allied to pelicans and cormorants. and then after a few free vertebræ in the lower part of the back, succeeds the long sacrum, formed in the usual way, of many vertebræ. i described a sacrum of this type from the wealden beds, under the name _ornithodesmus_, referable to another species, which in many respects was so like the sacrum of a bird that i could not at the time separate it from the bird type. this genus has a sternum with a strong deep keel, and the articulation for the coracoid bones placed at the back of the keel in the usual way, but with a relation to each other seen in no genus hitherto known, for the articular surfaces are wedge-shaped instead of being ovate; and instead of being side by side, they obliquely overlap, practically as in wading birds like the heron. i have never seen any pterodactyle teeth so flattened and shaped like the end of a lancet; and from this character the form was known between mr. fox and his friends as "latidens." the name ornithodesmus is as descriptive of the sternum as of the vertebral column. the wing bones, as far as they are preserved, have the relatively great strength in the fore limb which is found in many of the pterodactyles of the cretaceous period, and are quite as large as the largest from the cambridge greensand. in the sussex species named _p. sagittirostris_ the lower jaw articulation was inches wide. [illustration: fig. . sternum of _ornithodesmus_ showing the overlapping facets for the coracoid bones (shaded) behind the median keel] [illustration: fig. . front of the keel of the sternum of _ornithodesmus latidens_ showing also the articulation for the coracoid bone] a few pterodactyles' bones have been discovered in the neocomian sands of england and germany, and other larger bones occur in the gault of folkestone and the north of france; but never in such association as to throw light on the aspect of the skeleton. ornithocheirus within my own memory pterodactyle remains were equally rare from the cambridge greensand. the late professor owen in one of his public lectures produced the first few fragments received from cambridge, and with a knowledge which in its scientific method seemed to border on the power of creation, produced again the missing parts, so that the bones told their story, which the work of waves and mineral changes in the rock had partly obliterated. subsequently good fortune gave me the opportunity during ten years to help my university in the acquisition and arrangement of the finest collection of remains of these animals in europe. out of an area of a few acres, during a year or two, came the thousand bones of ornithosaurs, mostly associated sets of remains, each a part of a separate skeleton, described in my published catalogues, as well as the best of those at york and in the british museum and other collections in london. the deposit which yields them, named cambridge greensand, may or may not represent a long period of time in its single foot of thickness; but the abundance of fossils, obtained whenever the workmen were adequately remunerated for preserving them, would suggest that the pterodactyles might have lived like sea-birds or in colonies like the penguins, if it were not that the number of examples of each species found is always small, and the many variations of structure suggested rather that the individuals represent the life of many lands. the collections of remains are mostly from villages in the immediate vicinity of cambridge, such as chesterton, huntingdon road, coldham common, haslingfield, barton, shillington, ditton, granchester, harston, barrington, stretching south to ashwell in bedfordshire on the one hand, as well as further north by horningsea into the fens. each appears to be the associated bones of a single individual. the remains mostly belong to comparatively large animals. some were small, though none have been found so diminutive as the smallest from the solenhofen slate. the largest specimens with long jaws appear to have had the head measuring not more than eighteen inches in length, which is less than half the size of the great toothless pterodactyles from kansas. [illustration: fig. . restoration of the skull of ornithocheirus the parts left white are in the geological museum at cambridge. the shaded parts have not been found. the two holes are the eye and the nostril (from the cambridge greensand)] the cambridge specimens manifestly belong to at least three genera. something may be said of the characters of the large animals which are included in the genus ornithocheirus. these fossils have many points of structure in common with the great american toothless forms which are of similar geological age. the skull is remarkable for having the back of the head prolonged in a compressed median crest, which rose above the brain case, and extended upward and over the neck vertebræ, so as to indicate a muscular power not otherwise shown in the group. for about three inches behind the brain this wedge of bone rested on the vertebræ, and probably overlapped the first three neural arches in the neck. another feature of some interest is the expansion of the bone which comes below the eye. in birds this malar or cheek bone is a slender rod, but in these pterodactyles it is a vertical plate, which is blended with the bone named the quadrate bone, which makes the articulation with the lower jaw in all oviparous animals. the beak varies greatly in length and in form, though it is never quite so pointed as in the american genus, for there is always a little truncation in front, when teeth are seen projecting forward from a position somewhat above the palate; the snout is often massive and sometimes club-shaped. except for these variations of shape in the compressed snout, which is characterised by a ridge in the middle of the palate, and a corresponding groove in the lower jaw, and the teeth, there is little to distinguish what is known of the skull in its largest english greensand fossils from the skull remains which abound in the chalk of kansas. this english genus ornithocheirus, represented by a great number of species, had the neural arch of the neck bones expanded transversely over the body of the vertebra in a way that characterises many birds with powerful necks, and is seen in a few pterodactyles from solenhofen. it is difficult to resist the conclusion that the neck vertebræ were not usually more than twice to three times as long as those of the back, and it would appear that the caudal vertebræ in the english cretaceous types were comparatively large, and about twice as long as the dorsal vertebræ. unless there has been a singular succession of accidents in the association of these vertebræ with the other remains, ornithocheirus had a tail of moderate length, formed of a few vertebræ as long as those of the neck, though more slender, quite unlike the tail in either the long-tailed or short-tailed groups of solenhofen pterodactyles, and longer than in the toothless pterodactyles of america. [illustration: fig. . cervical vertebra, ornithocheirus under side, half natural size. (cambridge greensand)] the singular articulation for the humerus at the truncated extremity of the coracoid bone is a character of this group, as is the articulation of the scapulæ with the neural arches of the dorsal vertebræ, at right angles to them (p. ), instead of running over the ribs as in birds and as in other pterodactyles. the smaller pterodactyles have their jaws less compressed from side to side. the upper arm bone, the humerus, instead of being truncated at its lower end as in ornithocheirus, is divided into two or three rounded articular surfaces. that for the radius, the bone which carries the wrist, is a distinct and oblique rounded facet, while the ulna has a rounded and pulley-like articulation on which the hand may rotate. these differences are probably associated with an absence of the remarkable mode of union of the scapulæ with the dorsal vertebræ. but i have hesitated to give different names to these smaller genera because no example of scapula has come under my notice which is not truncated at the free end. i do not think this european type can be the nyctodactylus of professor marsh, in which sutures appear to be persistent between the bodies of the vertebræ and their arches, because no examples have been found at cambridge with the neural arches separated, although the scapula is frequently separated from the coracoid in large animals. [illustration: fig. . upper and lower jaws of an english pterodactyle from the chalk, as preserved] ornithostoma [illustration: fig. . the palate of the english toothless pterodactyle, ornithostoma] [illustration: fig. . types of the american toothless pterodactyle, ornithostoma named by marsh, pteranodon] the most interesting of all the english pterodactyle remains is the small fragment of jaw figured by sir richard owen in , which is a little more than two inches long and an inch wide, distinguished by a concave palate with smooth rounded margins to the jaws and a rounded ridge to the beak. it is the only satisfactory fragment of the animal which has been figured, and indicates a genus of toothless pterodactyles, for which the name ornithostoma was first used in . after some years professor marsh found toothless pterodactyles in kansas, and indicated several species. there are remains to the number of six hundred specimens of these american animals in the yale museum alone; but very little was known of them till professor williston, of lawrence, in kansas, described the specimens from the kansas university museum, when it became evident that the bones of the skeleton are mostly formed on the same plan as those of the cambridge greensand genus, ornithocheirus. they are not quite identical. professor williston adopts for them the name ornithostoma, in preference to pteranodon which marsh had suggested. both animals have the dagger-shaped form of jaw, with corresponding height and breadth of the palate. the same flattened sides to the snout, converging upwards to a rounded ridge, the same compressed rounded margin to the jaw, which represents the border in which teeth are usually implanted, and in both the palate has the same smooth character forming a single wide concave channel. years previously i had the pleasure of showing to professor marsh the remarkable characters of the jaw, shoulder-girdle bones, and scapulæ in the greensand pterodactyles while the american fossils were still undiscovered. i subsequently made the restoration of the shoulder-girdle (p. ). professor williston states to me that the shoulder-girdle bones in american examples of ornithostoma have a close resemblance to those of ornithocheirus figured in , as is evident from remains now shown in the british museum. it appears that the kansas bones are almost invariably crushed flat, so that their articular ends are distorted. the neck vertebræ are relatively stout as in ornithocheirus. the hip-girdle of the american ornithostoma can be closely paralleled in some english specimens of ornithocheirus, though each prepubic bone is triangular in the american fossils as in _p. rhamphastinus_. they are united into a transverse bar as in rhamphorhynchus, unknown in the english fossils. the femur has the same shape as in ornithocheirus; and the long tibia terminates in a pulley. there is no fibula. the sternum in both has a manubrium, or thick keel mass, prolonged in front of its articular facets for the coracoid bones, which are well separated from each other. four ribs articulate with its straight sides. the animal has four toes and the fifth is rudimentary; there are no claws to the first and second. [illustration: fig. . restoration of the skeleton of _ornithostoma ingens_ (marsh) from the niobrara cretaceous of western kansas. made by professor williston. the original has a spread of wing of about feet inches. fragments of larger individuals are preserved at munich] in the restoration which professor williston has made the wing metacarpal is long, and in the shortest specimen measures foot inches, and in the longest foot inches. this is exactly equal to the length of the first phalange of the wing finger. the second wing finger bone is inches shorter, the third is little more than half the length of the first, while the fourth is only - / inches long, showing a rapid shortening of the bones, a condition which may have characterised all the cretaceous pterodactyles. the short humerus, about foot long, and the fore-arm, which is scarcely longer, are also characteristic proportions of ornithostoma or pteranodon, as known from the american specimens. professor williston gives no details of the remarkable tail, beyond saying that the tail is small and short, and that the vertebræ are flat at the ends, without transverse processes. in the restoration the tail is shorter than in the short-tailed species from the lithographic slate, and unlike the tail in ornithocheirus. this is the succession of pterodactyles in geological time. their history is like that of the human race. in the most ancient nations man's life comes upon us already fully organised. the pterodactyles begin, so far as isolated bones are concerned, in the rhætic strata; perhaps in the muschelkalk or middle division of the trias. and from the beginning of the secondary time they live on with but little diversity in important and characteristic structures, and so far as habit goes, the great pterodactyles of the upper chalk of england cannot be said to be more highly organised than the earlier stiff-tailed genera of the lias or the oolites. there is nothing like evolution. no modification such as that which derives the one-toed horse or the two-toed ox from ancestors with a larger number of digits. on the other hand, there is little, if any, evidence of degeneration. the later pterodactyles do not appear to have lost much, although the tail in some of the solenhofen genera may be degenerate when compared with the long tail of dimorphodon; but the short-tailed types are found side by side with the long-tailed rhamphorhynchus. the absence of teeth may be regarded as degeneration, for they have presumably become lost, in the same way that birds now existing have lost the teeth which characterised the fossil birds--ichthyornis of the american greensand, and archæopteryx of the upper oolites of bavaria. but just as some of the earlier pterodactyles have no teeth at the extremity of the jaw, such as dorygnathus and rhamphorhynchus, so the loss of teeth may have extended backward till the jaws became toothless. the specimens hitherto known give no evidence of such a change being in progress. but just as the division of mammals termed edentata usually wants only the teeth which characterise the front of the jaw, yet others, like the great ant-eater of south america named myrmecophaga, have the jaws as free from teeth as the toothless pterodactyles or living birds, and show that in that order the teeth have no value in separating these animals into subordinate groups any more than they have among the monotremata, where one type has teeth and the other is toothless. the following table gives a summary of the geological history and succession in the secondary rocks of the principal genera of flying reptiles. -----------------------+---------------------------------------------- | names of the genera. geological formations. +-----------------------+---------------------- | british and european. | north american. -----------------------+-----------------------+---------------------- upper chalk | |} ornithostoma | |} (_pteranodon_) lower chalk |} ornithocheirus |} nyctodactylus upper greensand |} | ornithostoma | gault | | | -----------------------+ | | lower greensand | | | wealden | ornithodesmus | purbeck | doratorhynchus | -----------------------+ | portland |{ pterodactylus | |{ ptenodracon | kimeridge clay and |{ cycnorhamphus | solenhofen slate |{ diopecephalus | |{ rhamphorhynchus | coralline oolite |{ scaphognathus | | | oxford clay | | -----------------------+ | great oolite and | | stonesfield slate | rhamphocephalus | | | inferior oolite | | -----------------------+ | upper lias |{ campylognathus | |{ dorygnathus | lower lias | dimorphodon | -----------------------+ | rhætic | bones | | | muschelkalk | ? bones | -----------------------+-----------------------+---------------------- chapter xvi classification of the ornithosauria when an attempt is made to determine the place in nature of an extinct group of animals and the relation to each other of the different types included within its limits, so as to express those facts in a classification, attention is directed in the first place to characters which are constant, and persist through the whole of its constituent genera. we endeavour to find the structural parts of the skeleton which are not affected by variation in the dentition, or the proportions of the extremities, or length of the tail, which may define families or genera, or species. it has already been shown that while in many ways the ornithosaurian animals are like birds, they have also important resemblances to reptiles. they are often named pterosauria. the wing finger gives a distinctive character which is found in neither one class of existing animals nor the other, and is common to all the pterodactyles at present known. they have been named ornithosauria as a distinct minor division of back-boned animals, which may be regarded as neither reptiles nor birds in the sense in which those terms are used to define a lizard or ostrich among animals which still exist. it is not so much that they mark a transition from reptile to bird, as that they are a group which is parallel to birds, and more manifestly holds an intermediate place than birds do between reptiles and mammals. in plan of structure bird and reptile have more in common than was at one time suspected. the late professor huxley went so far as to generalise on those coincidences in parts of the skeleton, and united birds and reptiles into one group, which he named sauropsida, to express the coincidences of structure between the lizard and the bird tribes. the idea is of more value than the term in which it is expressed, because reptiles are not, as we have seen, a group of animals which can be defined by any set of characters as comprehensive as those which express the distinctive features of birds. from the anatomist's point of view birds are a smaller group, and while some reptiles have affinity with them, it is rather the extinct than the living groups which indicate that relation. other reptiles have affinities of a more marked kind with mammals, and there are points in the ornithosaurian skeleton which are distinctly mammalian. so that when the monotreme mammals are united with south african reptiles known as theriodontia, which resemble them, in a group termed theropsida to express their mammalian resemblances, it is evident that there is no one continuous chain of life or gradation in complexity of structure of animals. we have to determine whether the ornithosauria incline towards the sauropsidan or bird-reptile alliance, or to the mammal-reptile or theropsidan alliance. there can be no doubt that the predominant tendency is to the former, with a minor affinity towards the latter. the ornithosauria are one of a series of groups of animals, living and extinct, which have been combined in an alliance named the ornithomorpha. that group includes at least five great divisions of animals, which circle about birds, known as ornithosauria, crocodilia, saurischia, aves, ornithischia, and aristosuchia. their relations to each other are not evident in an enumeration, but may be shown in some degree in a diagram (see p. ). the ornithomorpha the ornithomorpha arranged in this way show that the three middle groups--carnivorous saurischia, aristosuchia, herbivorous ornithischia--which are usually united as dinosauria, intervene between birds and ornithosaurs; and that the crocodilia and ornithosauria are parallel groups which are connected with birds, by the group of dinosaurs, which resembles birds most closely. the ornithomorpha is only one of a series of large natural groups of animals into which living and extinct terrestrial vertebrata may be arranged. and the succeeding diagram may contribute to make evident the relations of ornithosauria to the other terrestrial vertebrata (see p. ). herein it is seen that while the ornithomorpha approach towards mammalia through the ornithosauria, and less distinctly through the crocodilia, they approach more directly to the sauromorpha, through the plesiosaurs and hatteria; while that group also approaches more directly to the mammals through the plesiosaurs and anomodonts. [illustration: diagram of the affinities of the orders of animals comprised in the ornithomorpha. after a diagram in the _philosophical transactions of the royal society_, .] the aristosuchia is imperfectly known, and therefore to some extent a provisional group. it is a small group of animals. [illustration: diagram showing the relations of the ornithomorpha to the chief large groups of terrestrial vertebrata, and their affinities with each other. after a diagram in the _philosophical transactions of the royal society_, .] cordylomorpha are ichthyosaurs and the labyrinthodont group. herpetomorpha include lacertilia, homoeosauria, dolichosauria, chameleonoidea, ophidia, pythonomorpha. the sauromorpha comprises the groups of extinct and living reptiles named chelonia, rhynchocephala, sauropterygia, anomodontia, nothosauria, and protorosauria. these details may help to explain the place which has been given to the ornithosauria in the classification of animals. [illustration: fig. . comparison of six genera the skulls are seen on the left side in the order of the names below them] turning to the pterodactyles themselves, von meyer divided them naturally into short-tailed and long-tailed. the short-tailed indicated by the name pterodactylus he further divided into long-nosed and short-nosed. the short-nosed genus has since been named ptenodracon (fig. , p. ). the long-tailed group was divided into two types--the rhamphorhynchus of the solenhofen slate (fig. , p. ) and the english form now known as dimorphodon (fig. , p. ), which had been described from the lias. the cretaceous pterodactyles form a distinct family. so that, believing the tail to have been short in that group (fig. ), there are two long-tailed as well as two short-tailed families, which were defined from their typical genera pterodactylus, ornithocheirus, rhamphorhynchus, and dimorphodon. the differences in structure which these animals present are, first: the big-headed forms from the lias like dimorphodon, agree with the rhamphorhynchus type from solenhofen in having a vacuity in the skull defined by bone, placed between the orbit of the eye and the nostril. with those characters are correlated the comparatively short bones which correspond to the back of the hand termed metacarpals, and the tail is long, and stiffened down its length with ossified tendons. these characters separate ornithosaurs with long tails from those with short tails. the short-tailed types represented by pterodactylus and ornithocheirus have no distinct antorbital vacuity in the skull defined by bone. the metacarpal bones of the middle hand are exceptionally elongated, and the tail, which was flexible in both, appears to have been short. these differences in the skeleton warrant a primary division of flying reptiles into two principal groups. the short-tailed group, which was recognised by de blainville as intermediate between birds and reptiles, may take the name pterodactylia, which he suggested as a convenient, distinctive name. it may probably be inconvenient to enlarge its significance to comprise not only the true pterodactyles originally defined as pterosauria, but the newer ornithostoma and ornithocheirus which have been grouped as ornithocheiroidea. the second order, in which the wing membrane appears to have had a much greater extent, in being carried down the hind limbs, where the outermost digit and metatarsal are modified for its support, has been named pterodermata, to include the types which are arranged around rhamphorhynchus and dimorphodon. both these principal groups admit of subdivision by many characters in the skeleton, the most remarkable of which is afforded by the pair of bones carried in front of the pubes, and termed prepubic bones. in the pterodactyle family the bones in front of the pubes are always separate from each other, always directed forward, and have a peculiar fan-shaped form with concave sides like the bone which holds a similar position in a crocodile. in the ornithocheirus family the prepubic bones appear to have been originally triangular, but were afterwards united so as to form a strong continuous bar which extends transversely across the abdomen in advance of the pubic bones. this at least is the distinctive character in the genus ornithostoma according to professor williston, which in many ways closely resembles ornithocheirus. the two families in the long-tailed order named pterodermata are separated from each other by a similar difference in their prepubic bones. in dimorphodon those bones are separate from each other, and remain distinct through life, meeting in the middle line of the body in a wide plate. on the other hand, in rhamphorhynchus the prepubic bones, which are at first triangular and always slender, become blended together into a slight transverse bar, which only differs from that attributed to ornithostoma in its more slender bow-shaped form. [illustration: fig. . left side of pelvis of ornithostoma (after williston)] thus if other characters of the skeleton are ignored and a classification based upon the structure of the pelvis and prepubic bones, there would be some ground for associating the long-tailed rhamphorhynchus from the upper oolites which is losing the teeth in the front of its jaw with the cretaceous ornithostoma, which has the teeth completely wanting; while the long-tailed dimorphodon would come into closer association with the short-tailed pterodactylus. the drum-stick bone or tibia in dimorphodon, with its slender fibula, like that of a bird, also resembles a bird in the rounded and pulley-shaped terminal end which makes the joint corresponding to the middle of the ankle bones in man. the same condition of a terminal pulley joint is found in the cretaceous pterodactyles. but in the true pterodactyles and in rhamphorhynchus there usually is no pulley-shaped termination to the lower end of the drum-stick, for the tarsal bones remain separate from each other, and form two rows of ossifications, showing the same differences as separate dinosaurs into the divisions which have been referred to, from their bird-like pelvis and tibio-tarsus, as ornithischia in the one case, and saurischia in the other from their bones being more like those of living lizards. chapter xvii family relations of pterodactyles to animals which lived with them enough has been said of the general structure of pterodactyles and the chief forms which they assumed while the secondary rocks were accumulating, to convey a clear idea of their relations to the types of vertebrate animals which still survive on the earth. we may be unable to explain the reasons for their existence, and for their departure from the plan of organisation of reptiles and birds. but the evidence has not been exhausted which may elucidate their existence. sometimes, in problems of this kind, which involve comparison of the details of the skeleton in different animals, it is convenient to imagine the possibility of changes and transitions which are not yet supported by the discovery of fossil remains. if, for example, the pterodactyle be conceived of as divested of the wing finger, which is its most distinctive character, or that finger is supposed to be replaced by an ordinary digit, like the three-clawed digits of the hand which we have regarded as applied to the ground, where, it may be asked, would the animal type be found which approximates most closely to a pterodactyle which had been thus modified? there are two possible replies to such a question, suggested by the form of the foot. for the old bird archæopteryx has three such clawed digits, but no wing finger. and some dinosaurs also have the hand with three digits terminating in claws, which are quite comparable to the clawed digits of pterodactyles. the truth expressed in the saying that no man by taking thought can add a cubit to his stature is of universal application in the animal world, in relation to the result upon the skeleton of the exercise of a function by the individual. yet such is the relation in proportions of the different parts of the animal to the work which it performs, so marked is the evidence that growth has extended in direct relation to use of organs and active life, and that structures have become dwarfed from overwork, or have wasted away from disuse--seen throughout all vertebrate animals, that we may fairly attribute to the wing finger some correlated influence upon the proportions of the animal, as a consequence of the dependence of the entire economy upon each of its parts. therefore if an allied animal did not possess a wing finger, and did not fly, it might not have developed the lightness of bone, or the length of limb which pterodactyles possess. the mere expansion of the parachute membrane seen in so-called flying animals, both mammals and reptiles, which are devoid of wings, is absolutely without effect in modifying the skeleton. but when in the bat a wing structure is met with which may be compared to a gigantic extension of the web foot of the so-called flying frog, the bones of the fingers and the back of the hand elongate and extend under the stimulus of the function of flight in the same way as the legs elongate in the more active hoofed animals, with the function of running. therefore it is not improbable that the limbs shared to some extent in growth under stimulus of exercise which developed the wing finger. and if an animal can be found among fossils so far allied as to indicate a possible representative of the race from which these flying dragons arose, it might be expected to be at least shorter legged, and possibly more distinctly reptilian in the bones of the shoulder-girdle which support the muscles used in flight. it may readily be understood that the kinds of life which were most nearly allied to pterodactyles are likely to have existed upon the earth with them, and that flight was only one of the modes of progression which became developed in relation to their conditions of existence. the principal assemblage of terrestrial animals available for such comparison is the dinosauria. they may differ from pterodactyles as widely as the insectivora among mammals differ from bats, but not in a more marked way. comparisons will show that there are resemblances between the two extinct groups which appeal to both reason and imagination. dinosaurs are conveniently divided by characters of the pelvis first into the order saurischia, which includes the carnivorous megalosaurus and the cetiosaurus, with the pelvis on the reptile plan; and secondly the order ornithischia, represented by iguanodon, with the pelvis on the bird plan. it may be only a coincidence, but nevertheless an interesting one, that the characters of those two great groups of reptiles, which also extend throughout the secondary rocks, are to some extent paralleled in parts of the skeleton of the two divisions of pterodactyles. this may be illustrated by reference to the skull, pelvis, hind limb, and the pneumatic condition of the bones. [illustration: fig. . comparison of the skull of the dinosaur anchisaurus with the ornithosaur dimorphodon] the saurischian dinosauria have an antorbital vacuity in the side of the skull between the nasal opening and the eye, as in the long-tailed ornithosaurs named pterodermata. in some of the older genera of these carnivorous dinosaurs of the trias, the lateral vacuities of the head are as large as in dimorphodon. but in some at least of the iguanodont, or ornithischian dinosaurs, there is no antorbital vacuity, and the side of the face in that respect resembles the short-tailed pterodactylia. the skull of a carnivorous dinosaur possesses teeth which, though easily distinguished from those of pterodactyles, can be best compared with them. the most striking difference is in the fact that in the dinosaur the nostrils are nearly terminal, while in the pterodactyle they are removed some distance backward. this result is brought about by growth taking place, in the one case at the front margin of the maxillary bone so as to carry the nostril forward, and in the other case at the back margin of the premaxillary bone. thus an elongated part of the jaw is extended in front of the nostril. hence there is a different proportion between the premaxillary and maxillary bones in the two groups of animals, which corresponds to the presence of a beak in a bird, and its absence in living reptiles. it is not known whether the extremity of the pterodactyle's beak is a single bone, the intermaxillary bone, such as forms the corresponding toothless part of the jaw in the south african reptile dicynodon, or whether it is made by the pair of bones called premaxillaries which form the extremity of the jaw in most dinosaurs. too much importance may perhaps be attached to such differences which are partly hypothetical, because the extinct ichthyosaurus, which has an exceptionally long snout, has the two premaxillary bones elongated so as to extend backward to the nostrils. a similar elongation of those bones is seen in porpoises, which also have a long snout; and the bones are carried back from the front of the head to the nostrils, which are sometimes known as blowholes. but the porpoise has those premaxillary bones not so much in advance of the bones which carry teeth named maxillary, as placed in the interspace between them. the nostrils, however, are not limited to the extremity of the head in all dinosaurs. if this region of the beak in dimorphodon be compared with the corresponding part of a dinosaur from the permian rocks, or trias, the relation of the nostril to the bones forming the beak may be better understood. [illustration: fig. . comparison of the skull of the dinosaur ornithosuchus with the ornithosaur dimorphodon] in the sandstone of elgin, usually named trias, a small dinosaur is found, which has been named ornithosuchus, from the resemblance of its head to that of a bird. seen from above, the head has a remarkable resemblance to the condition in rhamphorhynchus, in the sharp-pointed beak and positions of the orbits and other openings. in side view the orbits have the triangular form seen in dimorphodon, and the preorbital vacuities are large, as in that genus, while the lateral nostrils, which are smaller, are further forward in the dinosaur. the differences from dimorphodon are in the articulation for the jaw being carried a little backward, instead of being vertical as in the pterodactyle, and the bone in front of the nose is smaller. notwithstanding probable differences in the palate, the approximation, which extends to the crocodile-like vacuity in the lower jaw, is such that by slight modification in the skull the differences would be substantially obliterated by which the skull of such an ornithosaur is technically distinguished from such a dinosaur. the back of the skull is clearly seen in the whitby pterodactyle, and its structure is similar to the corresponding part of such dinosaurs as anchisaurus or atlantosaurus, without the resemblance quite amounting to identity, but still far closer than is the resemblance between the same region in the heads of crocodiles, lizards, serpents, chelonians. few of these fossil dinosaur skulls are available for comparison, and those differ among themselves. the coincidences rather suggest a close collateral relation than prove the elaboration of one type from the other. they may have had a common ancestor. the trias rocks near stuttgart have yielded dinosaurs as unlike pterodactyles as could be imagined, resembling heavily armoured crocodiles, in such types as the genus belodon. its jaws are compressed from side to side, as in many pterodactyles, and the nostrils are at least as far backward as in rhamphorhynchus. belodon has preorbital vacuities and postorbital vacuities, but the orbit of the eye is never large, as in pterodactyles. it might not be worth while dwelling on such points in the skull if it were not that the pelvis in belodon is a basin formed by the blending of the expanded plates of the ischium and the pubis, into a sheet of bone which more nearly resembles the same region in pterodactyles than does the ischio-pubic region in other dinosaurian animals like cetiosaurus. the backbone in a few dinosaurs is suggestive of pterodactyles. in such genera as have been named coelurus and calamospondylus, in which the skeleton is only partially known, the neck vertebræ become elongated, so as to compare with the long-necked pterodactyles. the cervical rib is often very similar to that type, and blended with the vertebra, as in pterodactyles and birds. the early dorsal vertebræ of pterodactyles might almost be mistaken for those of dinosaurs. the tail vertebræ of a pterodactyle are usually longer than in long-tailed dinosauria. in the limbs and the bony girdles which support them there is more resemblance between pterodactyles and dinosaurs than might have been anticipated, considering their manifest differences in habit. thus all dinosaurs have the hip bone named ilium prolonged in front of the articulation for the femur as well as behind it, almost exactly as in pterodactyles and birds (see p. ). there is some difference in the pubis and ischium which is more conspicuous in form than in direction of the bones. there is a pterodactyle imperfectly preserved, named _pterodactylus dubius_, in which the ischium is directed backward and the pubis downward, and the bones unite below the acetabular cavity for the head of the femur to work in, but do not appear to be otherwise connected. in rhamphorhynchus the connexion between these two thickened bars is made by a thin plate of bone. in such a dinosaur as the american carnivorous ceratosaurus the two bars of the pubis and ischium remain separate and diverging, and there is no film of bone extending over the interspace between them. the development of such a bony condition would make a close approximation between the ornithosaurian pelvis and that of those dinosaurs which closely resemble pterodactyles in skull and teeth. [illustration: fig. . left side of pelvis a pterodactyle is shown between a carnivorous dinosaur above and a herbivorous dinosaur below] another pelvic character of some interest is the blending of the pubis and ischium of the right and left sides in the middle line of the body. there are some genera of dinosaurs like the english aristosuchus from the weald, and the american genera coelurus, ceratosaurus, and others, in which the pubic bones, instead of uniting at their extremities, are pinched together from side to side, and unite down the lower part of their length, terminating in an expanded end like a shoe, which is seen to be a separate ossification, and probably formed by a pair of ossifications joined in the median line. this small bone, which is below the pubes, and in these animals becomes blended with them, we may regard as a pair of prepubic bones like those of pterodactyles and crocodiles, except that they have lost the stalk-like portions, which in those animals are developed to compensate for the diminished length of the pubic bones. the prepubic bones may also be developed in iguanodon, in which a pair of bones of similar form remains throughout life in advance of the pubes, as in pterodactyles. in those dinosauria with the bird-like type of pelvis the pubic bone is exceptionally developed, sending one process backward and another process forward, so that there is a great gap between these diverging limbs to the bone. in the region behind the sternum to which the ribs were attached, and in front of the pelvis, is a pair of bones in iguanodon shaped like the prepubic bones of dimorphodon. they have sometimes been interpreted as a hinder part of the sternum, but may more probably be regarded as a pair of prepubic bones articulating each with the anterior process of the pubis (see fig. ). the small bones found at the extremities of the pubes in such carnivorous dinosaurs as aristosuchus are blended by bony union with the pubes. the bones in iguanodon are placed behind the sternal region without any attachment for sternal ribs, and the expanded processes converge forwards from the stalk and unite exactly like the prepubic bones of ornithosaurs. while this character, on the one hand, may link pterodactyles with the dinosaurs, on the other hand it may be a link between both those groups and the crocodiles, in which the front pair of bones of the pelvis has also appeared to be representative of the prepubic bones of flying reptiles (see fig. , p. ). [illustration: fig. . diagram of the pelvis seen from below in an ornithosaur and a dinosaur] the resemblances between pterodactyles and dinosaurs in the hind limb are not of less interest, though it is rather in the older pterodactyles such as dimorphodon, pterodactylus, and rhamphorhynchus that the resemblance is closest with the slender carnivorous dinosaurs. they never have the head of the thigh bone, femur, separated from its shaft by a constricted neck, as in the pterodactyles from the chalk. in many ways the thigh bone of dinosaurs tends towards being avian; while that of pterodactyles inclines towards being mammalian, but with a tendency to be bird-like in the older types, and to be mammal-like in the most recent representatives of the group in the chalk. the bones of the leg in ornithosaurs, known as tibia and fibula, are remarkable for the circumstance first that they resemble birds in the fibula being slender and only developed in its upper part towards the femur, and secondly that in a genus like dimorphodon this drum-stick bone has the two upper bones of the ankle blended with the tibia, so as to form a rounded pulley joint which is indistinguishable from that of a bird (see p. ). there is a large number of dinosaurs in which this remarkable distinctive character of birds is also found. only, dinosaurs like iguanodon, for instance, have the slender fibula as long as the tibia, and contributing to unite with the separate ankle bones of the similarly rounded pulley at the lower end. there are no birds in which the tarsal bones remain separated and distinct throughout life. but in pterodactylus from solenhofen, as in a number of dinosaurs, especially the carnivorous genera, the bones of the tarsus remain distinct throughout life, and never acquired such forms as would have enabled the ankle bone, termed astragalus, to embrace the extremity of the tibia, as it does in iguanodon. thus the resemblance of the ornithosaur drum-stick is almost as close to dinosaurs as to birds. there is great similarity between dinosaurs and pterodactyles seen in the region of the instep, known as the metatarsus. these bones are usually four in number, parallel to each other, and similar in form. they are commonly longer than in dinosaurs; but among some of the carnivorous dinosaurs their length approximates to that seen in pterodactyles. in neither group are the bones blended together by bony union, while they are always united in birds, as in oxen and similar even-hoofed mammals. dinosaurs agree with pterodactyles in maintaining the metatarsal bones separate, but they differ from them and agree with birds frequently, in having the number of metatarsal bones reduced to three, as in iguanodon, though dinosaurs often have as many as five digits developed. the toe bones, the phalanges of these digits of the hind limb, are usually longer in pterodactyles than in dinosaurs, but they resemble carnivorous dinosaurs in the forms of their sharp terminal bones for the claws, which are similarly compressed from side to side. so diverse are the functions of the fore limb in dinosaurs and pterodactyles, and so remarkably does the length of the metacarpal region of the back of the hand vary in the long-tailed and short-tailed ornithosaurs, that there is necessarily a less close correspondence in that region of the skeleton between these two groups of animals; for the pterodactyle fore limb is modified in relation to a function which can only be paralleled among birds and bats; and yet neither of those groups of animals approximates closely in this region of the skeleton to the flying reptile. under all the modifications of structure which may be attributed to differences of function, some resemblance to dinosaurs may be detected, which is best evident in the upper arm bone, humerus; is slight in the fore-arm bones, ulna and radius; and becomes lost towards the extremity of the limb. if the tendency of the thigh bone to resemble a mammalian type of femur (p. ) is a fundamental, deep-seated character of the skeleton, it might be anticipated that a trace of mammalian character would also be found in the humerus. for what the character is worth, the head of the humerus does show a closer approximation to a monotreme mammal than is seen in birds, and is to some extent paralleled in those south african reptiles which approximate to mammals most closely. not the least remarkable of the many astonishing resemblances of these light aerial creatures to the more heavy bodied dinosaurs is the circumstance that the humerus in both groups makes a not dissimilar approach to that of certain mammals. these illustrations may be accepted as demonstrating a relationship between the ornithosaurs and dinosaurs now compared, which can only be explained as results of influence of a common parentage upon the forms of the bones. but more interesting than resemblances of that kind is the similarity that may be traced in the way in which air is introduced into cavities in the bones in both groups. in some of the imperfectly known dinosaurs, like aristosuchus, coelurus, and thecospondylus, the bone texture is as thin as in pterodactyles, and the vertebræ are excavated by pneumatic cavities, which are amazing in size when compared with the corresponding structures in birds, for the vertebra is often hollowed out so that nothing remains but a thin external film like paper for its thickness. in the dinosaurian genus coelurus this condition is as well marked in the tail and back as it is in the neck. the essential difference from birds appears to be that in the larger carnivorous dinosaurs the pneumatic condition of the bones is confined to the vertebral column; while birds and pterodactyles have the pneumatic condition more conspicuously developed in the limb bones. the pneumatic skeleton, however, appears to be absent from the herbivorous types like iguanodon and all dinosaurs which have the bird-like form of pelvis, and are most bird-like in the forms of bones of the hind limb. it is possible that some of the carnivorous dinosaurs also possessed limb bones with pneumatic cavities. many of those bones are hollow with very thin walls. if their cavities were connected with the lungs the foramina are inconspicuous and unlike the immense holes seen in the sides of the vertebræ. according to the late professor marsh, the limbs of coelurus and its allies, which at present are imperfectly known, are in some cases pneumatic. therefore there is a closer fundamental resemblance between some carnivorous dinosaurs and pterodactyles than might have been anticipated. but the skull of coelurus is unknown, and the fragments of the skeleton hitherto published are insufficient to do more than show that the two types were near in kindred, though distinct in habit. each has elaborated a skeleton which owes much to the common stock which transmitted the vital organs, and the tendency of the bones to take special forms; but which also owes more than can be accurately measured to the action of muscles in shaping the bones and the influence of the mechanical conditions of daily life upon the growth of the bones in both of these orders of animals. enough is known to prove that all dinosaurs cannot be regarded as ornithosaurs which have not acquired the power of flight; though the evidence would lead us to believe that the primitive ornithosaur was a four-footed animal, before the wing finger became developed in the fore limb as a means of extending a patagial membrane, like the membrane which in the hind limb of dimorphodon has bent the outermost digit of the foot upward and outward to support the corresponding organ of flight extending down the hind legs. it may thus be seen that the characters of ornithosaurs which have already been spoken of as reptilian, as distinguished from the resemblances to birds, may now with more accuracy be regarded as dinosaurian. the dinosaurs, like pterodactyles, must be regarded as intermediate in some respects between reptiles and birds. the resemblances enumerated would alone constitute a partial transition from the reptile to the bird, although no dinosaurs have organs of flight; many are heavily armoured with plates of bone, and few, if any, approximate in the technical parts of the skeleton to the bird class, except in the hind limbs. yet dinosaurs have sometimes been regarded as standing to birds in the relation of ancestors, or as parallel to an ancestral stock. before an attempt can be made to estimate the mutual relation of the flying reptiles to dinosaurs on the one hand, and to birds on the other, it may be well to remember that the resemblance of such a dinosaur as iguanodon to a bird in its pelvis and hind limb is not more remarkable than that of pterodactyles to birds in the shoulder-girdle and bones of the fore limb. the keeled sternum, the long, slender coracoid bones and scapulæ, are absolutely bird-like in most ornithosaurs; and that region of the skeleton only differs from birds in the absence of a furculum which represents the clavicles, and is commonly named the "merry-thought." the elongated bones of the fore-arm and the hand, terminating in three sharp claws, are characters in which the fossil bird archæopteryx resembles the pterodactyle rhamphorhynchus, a resemblance which extends to a similar elongation of the tail. it is remarkable that the resemblance should be so close, since archæopteryx affords the only bird's skeleton known to be contemporary which can be compared with the solenhofen flying reptiles. the resemblance may possibly be closer than has been imagined. the back of the head of archæopteryx is imperfectly preserved in the region of the quadrate bone, malar arch, and temporal vacuity. and till these are better known it cannot be affirmed that the back of the head is more reptilian in pterodactyles than in the oldest birds. the side of the head in archæopteryx is distinguished by the nostril being far forward, the vacuity in front of the orbit being as large as in the pterodactyle scaphognathus from solenhofen and other long-tailed pterodactyles. chapter xviii how pterodactyles may have originated ornithosauria have many characters inseparably blended together which are otherwise distinctive of reptiles, birds, and mammals, and associated with peculiar structures which are absent from all other animals. they are not quite alone in this incongruous combination of different types of animals in the same skeleton. dinosaurs, which were contemporary with ornithosaurs, approximate to them in blending characters of birds with the structure of a reptile and something of a mammal in one animal. if an ornithosaur is reptilian in its backbone, in the articular ends of each vertebra having the cup in front and ball behind in the manner of crocodiles, serpents, and many lizards, a dinosaur like iguanodon, which had the reversed condition of ball in front and cup behind in its early vertebræ, may be more mammalian than avian in a corresponding resemblance of the bones to the neck in hoofed mammals. but while pterodactyles are sometimes mammalian in having the head of the thigh bone moulded as in carnivorous mammals and man, the corresponding bone in a dinosaur is more like that of a bird. and while the pterodactyle shoulder-girdle is often absolutely bird-like, that region in dinosaurs can only be paralleled among reptiles. such combinations of diverse characters are not limited to animals which are extinct. there were not wanting scientific men who regarded the platypus of australia, when first sent to europe, as an ingenious example of eastern skill, in which an animal had been compounded artificially by blending the beak of a bird with the body of a mammal. fuller knowledge of that remarkable animal has continuously intensified wonder at its combination of mammal, bird, and reptile in a single animal. it has broken down the theoretical divisions between the higher vertebrata, demonstrating that a mammal may lay eggs like a reptile or bird, that the skull may include the reptilian characters of the malar arch and pre-frontal and post-frontal bones, otherwise unknown in mammals and birds. the groups of mammals, birds, and reptiles now surviving on the earth prove to be less sharply defined from each other when the living and extinct types are considered together. but in pterodactyles, mammal bird and reptile lose their identity, as three colours would do when unequally mixed together. this mingling of characteristics of different animals is not to be attributed to interbreeding, but is the converse of the combination of characters found in hybrid animals. it is no exaggeration to say that there is a sense in which mammal, bird, reptile, and the distinctive structures of the ornithosaur, have simultaneously developed from one egg, in the body of one animal. the differences between those vertebrate types of animals consist chiefly in the way in which their organisation is modified, by one strain of characters being eliminated so that another becomes predominant, while a distinctive set of structures is elaborated in each class of animals. the earlier geological history of the higher vertebrata is very imperfectly known, but the evidence tends to the inference that the older representatives of the several classes approximate to each other more closely than do their surviving representatives, so that in still earlier ages of time the distinction between them had not become recognisable. the relation of the great groups of animals to each other, among vertebrata, is essentially a parallel relation, like the colours of the solar spectrum, or the parallel digits of the hand. it was natural, when only the surviving life on the earth was known, to imagine that animals were connected in a continuous chain by successive descent, but mammals have given no evidence of approximation to birds; and birds discover no evidence that their ancestors were reptiles, in the sense in which that word is used to define animals which now exist on the earth. when the variation which animals attain in their maturity and exhibit in development from the egg was first realised, it was imagined that nature, by slow summing up and accumulation of differences which were observed, would so modify one animal type that it would pass into another. there is little evidence to support belief that the changes between the types of life have been wrought in that way. the history of fossil animals has not shown transitions of this kind from the lower to higher vertebrata, but only intermediate, parallel groups of animals, analogous to those which survive, and distinct from them in the same way as surviving groups are distinct from each other. the circumstance that mammals, birds, and reptiles are all known low down in the secondary epoch of geological time, is favourable to the idea of their history being parallel rather than successive. such a conception is supported by the theory of elimination of characters from groups of animals as the basis of their differentiation. this loss appears always to be accompanied by a corresponding gain of characters, which is more remarkable in the soft, vital organs than in the skeleton. the gain in higher vertebrates in the bones is chiefly in the perfection of joints at their extremities; but the gain in brain, lungs, heart, and other soft parts is an elaboration of those structures and an increase in amount of tissue. the resemblances of ornithosaurs to mammals are the least conspicuous of their characters. those seen in the upper arm bone and thigh bone are manifestly not derived from mammals. they cannot be explained as adaptations of the bones to conditions of existence, because there is no community of habit to be inferred between pterodactyles and mammals, in which the bones are in any way comparable. other fossil animals show that a fundamentally reptilian structure is capable of developing in the mammalian direction in the skull, backbone, shoulder-girdle, hip-girdle, and limbs, so as to be uniformly mammalian in its tendencies. this is proved by tracing the north american texas fossils named labyrinthodonts, through the south african theriodonts, towards the monotremata and other mammalia. just as those animals have obliterated all traces of the bird from their skeletons, birds have obliterated the distinctive characters of mammals. the ornithosaur has partially obliterated both. with a skull and backbone marked by typical characters of the reptile, it combines the shoulder-girdle and hip-girdle of a bird, with characters in the limbs which suggest both those types in combination with mammals. the bones have been compared in the skeleton of each order of existing reptiles, and found to show side by side with their peculiar characters not only resemblances to the other reptilia, but an appreciable number of mammalian and avian characters in their skeletons. the term "crocodile," for example, indicates an animal in which the skeleton is dominated by one set of peculiar characters. crocodiles retain enough of the characteristics of several other orders of reptiles to show that an animal sprung from the old crocodile stock might diverge widely from existing crocodiles by intensifying what might be termed its dormant characters in the crocodile skeleton. comparing animals together bone by bone it is possible to value the modifications of form which they put on, and the resemblances between them, so as to separate the inherited wealth of an animal's affinities with ancestors or collateral groups, from the peculiar characters which have been acquired as an increase based upon its typical bony possessions or osteological capital. there is no part of the pterodactyle skeleton which is more distinctly modified than the head of the upper arm bone, which fits into the socket between the coracoid bone and the shoulder-blade. the head of the humerus, as the articular part is named, is somewhat crescent-shaped, convex on its inner border, and a little concave on its outer border, and therefore unlike the ball-shaped head of the upper arm bone in man and the higher mammals. it is much more nearly paralleled in the little group of monotremata allied to the living ornithorhynchus. in that sense the head of the humerus in a pterodactyle has some affinity with the lowest mammalia, which approach nearest to reptiles. the character might pass unregarded if it were not found in more striking development in fossil reptiles from cape colony, which from having teeth like mammals are named theriodontia. in several of those south african reptiles the upper arm bone approaches closer to the humerus in ornithosaurs than to ornithorhynchus. such coincidences of structure are sometimes dismissed from consideration and placed beyond investigation by being termed adaptive modifications; but there can be no hope of finding community of habit between the burrowing monotreme, the short-limbed theriodont, and the flying pterodactyle which might have caused this articular part of the upper arm bone to acquire a form so similar in animals constructed so differently. if the resemblance in the humerus to monotremes in this respect is not to be attributed to burrowing, neither can the crescent form of its upper articulation be attributed to flight; for in birds the head of the bone is compressed, but always convex, and bats fly without any approach to the pterodactyle form in the head of the humerus. this apparently trivial character may from such comparisons be inferred to be something which the way of life of the animal does not sufficiently account for. these deepest-seated parts of the limbs are slow to adapt themselves to changing circumstances of existence, and retain their characters with moderate variation of the bones in each of the orders or classes of animals. it therefore is safer to regard mammalian characters, as well as the resemblances which pterodactyles show to other kinds of animals, as due to inheritance from a time when there was a common stock from which none of these animals which have been considered had been distinctly elaborated. a few characters of ornithosaurs are regarded as having been acquired, because they are not found in any other animals, or have been developed only in a portion of the group. the most obvious of these is the elongated wing finger; but in some genera, like dimorphodon, there is also a less elongation of the fifth digit of the foot, and perhaps in all genera there is a backward development of the first digit of the hand, which is without a claw, and therefore unlike the clawed digit of a bat. an acquired character of another kind, which is limited to the cretaceous genera, is seen in the shoulder-blade being directed transversely outward, so that its truncated end articulates by a true joint with the early vertebræ of the back, and defended the cavity inclosed by the ribs by a strong bony external arch. and finally, as the animals later in time acquire short tails, and relatively longer limbs, the bones of the back of the hand, termed metacarpals, acquire greater and distinctive length, which is not seen in the long-tailed types like rhamphorhynchus. these and such-like acquired characters distinguish the class of animals from all groups with which it may be compared, and mark the possible limits of variation of the skeleton within the boundary of the order. but no further variation of these parts of the skeleton could make a transition to another order of animals, or explain how the pterodactyles came into existence, because the characters which separate orders and classes of animals from each other differ in kind from those which separate smaller groups, named genera and species, of which the order is made up. the accumulation of the characters of genera will not sum up into the characters of an order or class. in making the division of vertebrate animals into classes the skeleton is often almost ignored. its value is entirely empirical and based upon the observed association of the various forms of bones with the more important characters of the brain and other vital organs. what is understood as a mammalian or avian character in the skeleton is the form of bone which is found in association with the soft vital organs which constitute an animal a mammal or a bird. the characters which theoretically define a mammal appear to be the enormous overgrowth of the cerebral hemispheres of the brain by which the cerebrum comes into contact with the cerebellum, as among birds. this character distinguishes both groups of animals from all reptiles, recent and fossil. but in examining the mould of the interior of the brain case it is rare to have the bones fitting so closely to the brain as to prove that the lateral expansion below the cerebrum and cerebellum is formed by the optic lobes of the brain. otherwise the brain of a pterodactyle might be as like to the brain of ornithorhynchus as it is like that of a bird (fig. ). but it is precisely in this condition of arrangement of the parts of the brain that the specimens appear to be most clear. the lateral mass of brain in specimens of ornithosaurs from the lower secondary rocks appears to be transversely divided into back and front parts, which may be thought to correspond to the structures in a mammal brain named _corpora quadrigemina_, but to be placed as the optic lobes are placed in birds, and to have relatively greater dimensions than in mammals. no evidence has been observed of this transverse division of the optic lobes of the brain in pterodactyles from the chalk and cretaceous rocks, and so far as the evidence goes this part of the brain was shaped as in birds, but rather smaller. the brain is the only soft organ in which a mammalian character could be evidenced. the uniformity in character of the brain throughout the group in mammals is remarkable, in reference to the circumstance that the reproduction varies in type; the lowest, or monotreme division, being oviparous. if there is no necessary connexion between the mammalian brain and the prevalent condition under which the young are produced alive, it may be affirmed also that there is no necessary connexion between the form of the brain and the form of the bones, since the brain cavity in theriodont reptiles shows no resemblance to that of a mammal, while the bones are in so many respects only paralleled among monotremata and mammalia. the variety of forms which the existing mammalian orders of animals assume, shows the astonishing range of structure of the skeleton which may coexist with the mammalian brain. and therefore we are led to the conclusion that any other fundamental modification of brain--such as distinguishes the class of birds--might also be associated with forms and structures of the skeleton which would vary in similar ways. in other words, if for convenience we define a mammal by its form of brain, structure of the heart and lungs, and provision for nutrition of the young, without regard to the covering of the skin, which varies between the scales of a pangolin and the practically naked skin of the whale--a bird might be also defined by its peculiar conditions of brain and lungs, without reference to the feathered condition of the skin, though the feathered condition extends backward in time to the upper secondary rocks, as seen in the archæopteryx. the avian characters of pterodactyles are the predominant parts of their organisation, for the conditions of the brain and lungs shown by the moulds of the brain case and the thin hollow bones with conspicuous pneumatic foramina, give evidence of a community of vital structures with birds, which is supported by characters of the skeleton. if any classificational value can be associated with the distribution of the pneumatic foramina as tending to establish membership of the same class for animals fashioned on the same plan of soft organs, the evidence is not weakened when a community of structures is found to extend among the bones to such distinctive parts of the skeleton as the sternum, shoulder-girdle, bones of the fore-arm and fore-leg; for in all these regions the pterodactyle bones are practically indistinguishable from those of birds. this is the more remarkable because other parts of the skeleton, such as the humerus and pelvis, show a partial resemblance to birds, while the parts which are least avian, like the neck bones, have no tendency to vary the number of the vertebræ, in the way which is common among birds, following more closely the formula of the seven cervical vertebræ of mammals. it would therefore appear from the vital community of structures with birds, that pterodactyles and birds are two parallel groups, which may be regarded as ancient divergent forks of the same branch of animal life, which became distinguished from each other by acquiring the different condition of the skin, and the structures which were developed in consequence of the bony skeleton ministering to flight in different ways; and with different habit of terrestrial progression, this extinct group of animals acquired some modifications of the skeleton which birds have not shown. there is nothing to suggest that pterodactyles are a branch from birds, but their relation to birds is much closer, so far as the skeleton goes, than is their relation with the flightless dinosaurs, with which birds and pterodactyles have many characters in common. on the theory of elimination of character which i have used to account for the disappearance of some mammalian characters from the pterodactyle, that loss is seen chiefly in the removal of the parts which have left a reptilian articulation of the lower jaw with the skull, and the articulation of the vertebræ throughout the vertebral column by a modified cup-and-ball form of joint. the furculum of the bird is always absent from the pterodactyle. no specimen has shown recognisable clavicles or collar-bones. judged by the standard of existing life, pterodactyles belong to the same group as birds, on the evidence of brain and lungs, but they belong to a different group on account of the dissimilar modifications of the skeleton and apparent absence of feathers from the skin. the most impressive facts in the pterodactyle skeleton, in view of these affinities, are the structures which it has in common with reptiles. some structures are fundamental, like the cup-and-ball articulation of the vertebræ, which is never found in birds or mammals. although not quite identical with the condition in any reptile, this structure is approximately lizard-like or crocodile-like in the cup-and-ball character. it shows that the deepest-seated part of the skeleton is reptile-like, though it may not be more reptilian than is the vertebral column of a mammal, if comparison is made between mammals and extinct groups of animals known as reptiles, such as dinosaurs and theriodontia. the orders of animals which have been included under the name reptilia comprise such different structural conditions of the parts of the skeleton which may be termed reptilian in ornithosaurs, that there is good reason for regarding the cup-and-ball articulation as quite a distinctive reptilian specialisation, in the same sense that the saddle-shaped articulation between the bodies of adjacent vertebræ in a bird is an avian specialisation. from the theoretical point of view the ornithosaur acquired its reptilian characters simultaneously with its avian and mammalian characters. there is nothing in the structure of the skeleton of the dinosauria, to which ornithosaurs approximate in several parts of the body, which would help to explain the cup-and-ball articulation of the backbone, if the flying reptile were supposed to be an offshoot from the carnivorous dinosaurs. the elimination of reptile characters from so much of the skeleton, and the substitution for them of the characters of birds and mammals, would be of exceptional interest if there had been any ground for regarding the flying animal as more nearly related to a reptile than to a bird. but if the evidence from the form of the brain and nature of the pneumatic organs seen in the limb bones accounts for the avian features of the skeleton, the reptilian condition of the vertebral column helps to show a capacity for variation, and that the fixity of type and structure, which the skeleton of the modern bird has attained, is not necessarily limited to or associated with the vital organs of birds. the variation of the cup-and-ball articulation in the neck of a chelonian, which makes the third vertebra cupped behind, the fourth bi-convex, the fifth cupped in front, and the sixth flattened behind, shows that too much importance may be attached to the mode of union of these bones in serpents, crocodiles, and those lizards which have the cup in front; for while in lizards the anterior cup, oblique and depressed, is found in most of its groups, the geckos show no trace of the cup-and-ball structure, and in that respect resemble the hatteria of new zealand. if, therefore, the cup-and-ball articulation of vertebræ in ornithosauria has any significance as a mark of affinity to reptiles, it could only be in approximation to those living reptiles which possess the same character, and would have it on the hypothesis that both have preserved the structure by descent from an earlier type of animal. this hypothesis is negatived by the fact that the cup-and-ball articulation is unknown in the older fossil reptiles. although the articulation for the lower jaw with the skull in ornithosaurs is only to be paralleled among reptiles, the structure is adapted to a brain case which is practically indistinguishable from that of a bird, except for the postorbital arch. the hypothesis of descent, therefore, becomes impossible, in any intelligible form, in explanation of distinctive character of the skeleton. the hypothesis of elimination may also seem to be insufficient, unless the potential capacity for new development be recognised as concurrent, and as capable of modifying each region of the skeleton, or hard parts of the animal, in the same way that the soft organs may be modified. from which we infer that all structures, which distinguish the several grades of organisation in modern classifications, soft parts and hard parts alike, may come into existence together, in so far as they are compatible with each other, in any class or ordinal division of animals. although the young mammal passes through a stage of growth in which the brain may be said to be reptilian, there is no good ground for inferring that mammal or bird type of skeleton was developed later in time than that of reptiles. the various types of fishes have the brains in general so similar to those of reptiles that it is more intelligible for all the vertebrate forms of brain to have differentiated at the same time, under the law of elimination of characters, than that there should be any other bond of union between the classes of animals. if we ask what started the ornithosauria into existence, and created the plan of construction of that animal type, i think science is justified in boldly affirming that the initial cause can only be sought under the development of patagial membranes, such as have been seen in various animals ministering to flight. such membranes, in an animal which was potentially a bird in its vital organs, have owed development to the absence of quill feathers. thus the wing membrane may be the cause for the chief differences of the skeleton by which ornithosaurs are separated from birds, for the stretch of wing in one case is made by the skin attached to the bones, and in the other case by feathers on the skin so attached as to necessitate that the wing bones have different proportions from ornithosaurs. it is a well-known observation that each great epoch of geological time has had its dominant forms of animal life, which, so far as the earth's history is known now, came into existence, lived their time, and were seen no more. in the same way the smaller groups of species and genera included in an ordinal group of animals or class have abounded, giving a tone to the life of each geological formation, until the vitality of the animal is exhausted, and the species becomes extinct or ceases to preponderate. this process is seen to be still modifying the life on the earth, when some kinds of animals and plants are introduced to new conditions. plants appear to wage successful war more easily than animals. the introduction of the cactus in some parts of cape colony has locally modified both the fauna and flora, just as the anacharis introduced into england spread from cambridge over the whole country, and became for many years the predominant form of plant life in the streams. the rabbit in australia is a historic pest. something similar to this physical fertility and increase appears to take place under new circumstances in certain organs within the bodies of animals, by the development of structures previously unknown. a familiar example is seen in the internal anatomy of the trout introduced into new zealand, where the number of pyloric appendages about the stomach has become rapidly augmented, while the size and the form of the animal have changed. the rapidity with which some of these changes have been brought about would appear to show that nature is capable of transforming animals more rapidly than might have been inferred from their uniform life under ordinary circumstances. growth of the vital organs in this way may modify the distinctive form of any vital organ, brain or lungs, and thus as a consequence of modification of the internal structures due to changes of food and habit, bring a new group of animals into existence. and just as the group of animals ceases to predominate after a time, so there comes a limit to the continued internal development of vital structures as their energy fails, for each organ behaves to some extent like an independent organism. under such explanations of the mutual relations of the parts of animals, and groups of animals, time ceases to be a factor of primary importance in their construction or elaboration. the supposed necessity for practically unlimited time to produce changes in the vital organs which separate animals into great orders or classes is a nightmare, born of hypothesis, and may be profitably dismissed. the geological evidence is too imperfect for dogmatism on speculative questions; but the nature of the affinities of ornithosaurs to other animals has been established on a basis of comparison which has no need of theory to justify the facts. it is not improbable that the primary epoch of time, even as known at present, may be sufficiently long to contain the parent races from which ornithosaurs and all their allies have arisen. in thus stating the relation of ornithosaurs to other animals the flying reptile has been traced home to kindred, though not to its actual parents or birthplace. there is no geological history of the rapid or gradual development of the wing finger, and although the wing membrane may be accepted as its cause of existence, the wing finger is powerfully developed in the oldest known pterodactyles as in their latest representatives. pterodactyles show singularly little variation in structure in their geological history. we chronicle the loss of the tail and loss of teeth. there is also the loss of the outermost wing digit from the hind foot as a supporter of the wing membrane. but the other variations are in the length of the metacarpus, or of the neck, or head. one of the fundamental laws of life necessitates that when an animal type ceases to adapt its organisation and modify its structures to suit the altered circumstances forced upon it by revolutions of the earth's surface its life's history becomes broken. it must bend or break. the final disappearance of these animals from the earth's history in the chalk may yet be modified by future discoveries, but the flying reptiles have vanished, in the same way as so many other groups of animals which were contemporary with them in the secondary period of time. such extinctions have been attributed to catastrophes, like the submergence of land, so that the habitations of animals became an area gradually decreasing in size, which at last disappeared. it appears also to be a law of life, illustrated by many extinct groups of animals, that they endure for geological ages, and having fought their battle in life's history, grow old and unable to continue the fight, and then disappear from the earth, giving place to more vigorous types adapted to live under new conditions. the extinct pterodactyles hold a relation to birds in the scheme of life not unlike that which monotremata hold to other mammals. both are remarkable for the variety of their affinities and resemblances to reptiles. the ornithosauria have long passed away; the monotremes are nearing extinction. both appear to be supplanted by parallel groups which were their contemporaries. birds now fill the earth in a way that flying reptiles never surpassed; but their flight is made in a different manner, and the wing is extended to support the animal in the air, chiefly by appendages to the skin. if these fossils have taught that ornithosaurs have a community of soft vital organs with dinosaurs and birds, they have also gone some way towards proving that causes similar to those which determined the structural peculiarities of their bony framework, originated the special forms of respiratory organs and brain which lifted them out of association with existing reptiles. these old flying animals sleep through geological ages, not without honour, for the study of their story has illuminated the mode of origin of animals which survive them, and in cleaving the rocks to display their bones we have opened a new page of the book of life. appendix the best public collections of ornithosaurian remains in england are in the british museum (natural history); museum of practical geology, royal college of surgeons; the university museum, oxford; geological museum, cambridge; and the museum of the philosophical society at york. detailed descriptions and original figures of the principal specimens mentioned or referred to may be found in the following writings:-- h. v. meyer, _reptilien aus dem lithograph_. _schiefer_. . folio. v. quenstedt, _pterodactylus suevicus_. . to. goldfuss, _nova acta leopold_. xv. v. munster, _nova acta leopold_. xv. a. wagner, _abhandl. bayerischen akad._, vi., viii. cuvier, _annales du museum_, xiii. . " _ossemens fossiles_, v. . buckland, _geol. trans._, ser. , iii. r. owen, _palæontographical society_. , , , , . k. v. zittel, _palæontographica_, xxix. . t. c. winkler, _mus. teyler archives_. , . oscar fraas, _palæontographica_, xxv. . anton fritsch, _böhm. gesell. sitzber_. . r. lydekker, _catalogue of fossil reptilia in british museum_ i. . o. c. marsh, _amer. jour. science_. , . s. w. williston, _kansas university quarterly_. , . e. t. newton, _phil. trans. royal soc._ , . h. g. seeley, _ornithosauria_. vo. . " _annals and mag. natural hist._ , , , . " _linn. society_. , . " _geol. mag._ . felix pleininger, _palæontographica_. , . index a abdominal ribs, , accumulation of characters, acetabulum, acquired characters, adjacent land, air cells, , albatross, , , alligator, brain, ; pelvis, american greensand, -- ornithosaurs, , amphibia, , anabas, anacharis, anchisaurus, angle of lower jaw, ankle bones, , , anomodonts, ant-eater of africa, ; india, ; south america, , apteryx, lungs, ; pelvis, aquatic mammals, aramis, scapular arch, archæopteryx, , , , , , aristosuchus, , , , armadillo, , articulation of the jaw, , ashwell, atlantosaurus, atlas and axis, , aves, avian characters, , b backbone, , banz, barbastelle, barrington, barton, bat, , , ; sternum of, ; metacarpus, bavaria, , beak, horny, , bear, skull of, ; femur, bel and the dragon, belodon, bird, , , -- resemblances, , , , , , , , , , bird-reptile, bird wing, , birds in flight, ; with teeth, black-headed bunting, blainville, d. de, , blood, temperature of, bohemia, bonaparte, prince charles, bones of birds, variation in, -- of reptiles, variation in, -- about the brain, -- in the back, bone texture, , bonn museum, , , brain and breathing organs, brain cavity, in birds and reptiles, ; in mammals, , ; in solenhofen pterodactyles, , brazil, breathing organs, bridgewater treatise, british museum, , brixton, isle of wight, , buckland, dean, , , burrowing limb, c cactus, calamospondylus, cambridge greensand, , , -- museum, camel, campylognathus, , , ; size of, canary, carnivorous dinosaurs, carpus, caudal fin, , -- vertebræ, , , ceratodus, , , , ceratosaurus, , cervical rib, cetacea, cetiosaurus, , chalinolobus, chalk, pterodactyles in, ; of kansas, , chameleon, , , ; scapula, ; sternum, chameleonoidea, cheek bones, chelonia, , , chesterton, chlamydosaurus, _chrysochloris capensis_, classification, ; on pelvis characters, ; of dinosaurs, clavicles, , claw, , , , coelurus, , coldham common, collar bone, collini, comparison with dinosaurs, ; of pelvis, , ; of skulls, , , cope, professor, , coracoid, , , cordylomorpha, cormorant, , ; sternum, corpora quadrigemina, crisp, dr., on pneumatic skeleton, crocodile, characters of, ; heart, ; lung, ; shoulder-girdle, ; skull, ; vertebræ, crocodilia, curlew, cuvier, , , , , , , , cycnorhamphus, , , , , _cycnorhamphus fraasii_, , , -- _suevicus_, , cypselus, d _dacelo gigantea_, darwin, davy, dr. john, deuterosaurus, dicynodon, _dicynodon lacerticeps_, digits, of ostrich, ; of pterodactyle, digits with claws, ; foot bones in, dimorphodon, , , , , , , , , , , , , , , , dinosauria, , , , , , , , , dinosaurs from lias, , ; from elgin, , ; stuttgart, ; trias dinosaurs, , diopecephalus, diving birds, , , dolichosauria, dolphin, doratorhynchus, dorygnathus, , dragons, , , drumstick bone, , duck, , e echidna, , , , edentata, edentulous beak, eichstädt, elephant, head of, enumeration of characters, , ephesus, winged figure, epiphysis to first phalange, exocoetus, extinctions, eye hole, ; sclerotic bones in, f farren, william, femur, fibula, , , fifth outer digit, ; in foot, figure from temple at ephesus, first phalange, fish-eating crocodile, flight, organs of, ; in bats, flying limb, flying fishes, , ; foxes, ; frogs, , ; gecko, , ; lizards, ; reptiles, , ; squirrel, foot, ; digits in, , fore leg, , -- limb, , , , four claws, fox, rev. w., , fraas, professor oscar, , frigate bird, vertebræ of, , frog, lungs of, furculum, g gaudry, professor a., gavial, gecko, , genera, comparison of, geological distribution, gills, giraffe, , glossy starling, golden eagle, -- mole, goldfuss, , granchester, great ant-eater, , guillemot, gull, h haarlem, teyler museum at, habits, probable, , , hairless skins, hand in mammals, harston, haslingfield, hastings, hatteria lung, , ; brain, ; skull, , ; ribs, ; a reptile type, head, characters of, heidelberg museum, , , herpetomorpha, heron, , hesperornis, hind foot, , -- limb, , , , hip-girdle in whale tribe, , homoeosauria, horningsea, horse, metacarpus of, ; vertebræ of, humerus, , , huxley, professor, , , , hyo-mandibular arch, hypothesis of descent, hyrax, i ichthyornis, ichthyosaurus, , iguanodon, ; pelvis, ilium, , , , , instep, , inherited characters, interclavicle, ischium, , , , isle of wight, j jaw, in birds, ; in fishes, ; in mammals, ; in reptiles, ; in pterodactyles, ; suspension of, , , -- lower, k kansas, chalk of, , , ; university museum of, kelheim, keuper, kimeridge clay, kingfisher, kiwi, l labyrinthodontia, lachrymal bones, laramie rocks, largest ornithosaur, lateral vacuities in skull, lawrence in kansas, lengths of bones, lepidosiren, lias, lithographic slate, , lizards, , , , llama, neck of, , loach, swim bladder of, lower jaw, , , , lumbar vertebræ, lungs, ; in apteryx, ; in chameleon, ; in ostrich, ; in reptiles, , , lydekker, r., , , lyme regis, m macrocercus, palate of, malar bone, mallard, mammal, , , , , , mammalia, , mammalian characters, , mammoth, manis, , , manubrium of sternum, , , marrow bones in a bird, marsh, professor o. c., , , , , , , , , , , , , marsupial, , , megalosaurus, , merganser, merry-thought, metacarpus, , , , , metatarsal bones, , , meyer, hermann von, , , , , , , , , , moa of new zealand, mole, humerus, ; sternum, monotremes, , , , , , mososaurus, movement of the leg, mugger, munich museum, , munster, von, muschelkalk, museum, , , , ; natural history, , myrmecophaga, n names of genera, natural history museum, , neck, ; in dimorphodon, ; in giraffe, ; in llama, ; in pterodactyles, ; in whales, newton, e. t., , , , , , new zealand bat, -- -- hatteria, niobrara rock, nostril, bones round the, ; small, notarium, , nothosauria, nusplingen, nyctodactylus, , o obliteration of characters, opercular bones, ophidia, , optic lobes, , organs of flight, ornithischia, , ornithocephalus, ornithocheirus, atlas and axis, ; brain, , ; carpus, ; cervical vertebra, , ; claw phalange, ; coracoid, ; femur, ; pelvis, ; pubic bones, ; sternum, ; shoulder-girdle, ; remains, ; teeth, , ; absence of teeth, _ornithocheirus machærorhynchus_, ; _microdon_, ornithocheiroidea, ornithodesmus, neck bones, , ; coracoid, , ; dorsal vertebræ, ; remains of _o. latidens_, ; _o. sagittirostris_, ornithomorpha, ornithorhynchus, , , , ornithosauria, , , , , , , , , , , , , , , , , , ornithostoma, , , , ; lower jaw, , ; pelvis, ; sternum, ; phalange, ; size, ; skull, , ornithosuchus, orycteropus, _ossa innominata_, ossified ligaments, ostrich, , , , , owen, sir r., , , , , , , , , , , owl, , oxford clay, , -- university museum, ox, vertebra of, ; metacarpus, p palate, bones of, pangolin, pappenheim, parallel groups, parrot, patagial membranes, pelican, pelvis, , - , , , , , penguin, , , , periophthalmus, peterborough, bones from, , phalanges, , ; wing finger, phillips, professor john, pigeon, platydactylus, platypus, plesiosaurus, , , , , pleininger, , pneumatic foramina, , , , , pond, mr., porcupine, porpoise, , , , premaxillary bones, , , prepubic bones, , - , , , protorosauria, _ptenodracon brevirostris_, , , , , pterodactyle aspects, ; avian characters, ; beak, ; brain, ; coracoid, ; discovery, , ; foot, ; fore limb, ; history in germany, , ; hand, ; hind limb, ; long tails, ; palate, ; sacrum, ; short tails, ; size, , ; sacrum, ; skull, ; teeth, ; vertebræ, pterodactyles from kansas chalk, , -- from lias clay, , , -- from neocomian sand, -- from oxford clay, -- from purbeck beds, -- from solenhofen slate, , -- from stonesfield slate, , pterodactylia, , , , _pterodactylus antiquus_, ; _brevirostris_, , , ; _crassirostris_, ; _dubius_, , , , ; _elegans_, ; _fraasii_, ; _grandipelvis_, , ; _grandis_, , , ; _kochi_, , , , , , ; _longirostris_, , , , , , , , ; _micronyx_, , ; _rhamphastinus_, ; _scolopaciceps_, , ; _spectabilis_, ; _suevicus_, pterodermata, , pteroid bone of first digit, pteromys, pterosauria, , pterygoid bones, , pythonomorpha, q quadrate bone, , , quenstedt, r rabbit, radius, , redshanks, relation between head and tail, , reptile, , , resin, restorations-- campylognathus, palate of, dimorphodon, , , ornithocheirus, ornithostoma, , ptenodracon, pterodactylus, , rhamphocephalus, rhamphorhynchus, , scaphognathus, rhacophorus, rhætic beds, rhamphocephalus, , , rhamphorhynchus, , ; foot, ; hind limb, ; pelvis, ; sacrum, ; skull, , - , ; sternum, ; tail, ; teeth, ; tibia and fibula, ; web-footed, _rhamphorhynchus curtimanus_, ; _hirundinaceus_, ; _longimanus_, ; _phyllurus_, , rhinoceros, , rhopoladon, rhynchocephala, roc, rochester, running limb, ryle, bishop, s sacrum, , st. george, st. ives, sarcorhamphus, saurians, saurischia, , , , sauromorpha, , sauropsida, sauropterygia, scaphognathus, , , , , , _scaphognathus crassirostris_, - , scapular arch, , scelidosaurus, sclerotic circle, seals, sedgwick, professor adam, v, shillington, shoebill, shoe-shaped prepubic bones, , short-tailed pterodactyles, , shoulder-girdle, , , , , siberia, simultaneous origin of characters, , skin covering, , , , , skulls, sloth, snipe, , solenhofen slate, , , , , sömmerring, south african reptiles, , , spotted fly-catcher, squamosal bone, , sternal ribs, sternum, , stonesfield slate, , , structures common to reptiles, stuttgart museum, , , swanage, swan, neck of, , swift, swimming limb, synotus, syrinx, t tail, description of, ; in cretaceous pterodactyles, -- long, ; short, ; in dimorphodon, ; in ornithocheirus, tanystrophoeus, long vertebræ in, tarsal bones, , tarso-metatarsus, teeth, , , ; in porpoise, temperature of blood, temporal arches, -- bone, -- fossa, teredo, texas fossils, thecospondylus, theriodont pelvis, -- reptiles, ; of russia, , ; of south africa, , theropsida, thigh bone, , , three claws, , tibia, , ; in iguanodon, toothless mammals, -- pterodactyles, , ; beak of pterodactyles, transition from reptiles to birds, tree frogs, trias dinosaurs, triceratops, pelvis of, trout, ; of new zealand, tuatera, tübingen museum, tundras, tunny, turtles, neck bones, u ulna, description of, uncinate process of ribs, unlimited time, upper arm bone, -- greensand, remains in, -- lias of whitby, -- oolites, , v variation of bones in mammals, -- in pterodactyles, variation of bones in vertebræ, vertebræ, caudal, , , -- cervical, , , -- dorsal, vertebral articulation, , -- column, vulture, neck vertebræ of, ; tibia and fibula of, vomer, vomerine bones, w wagler, wagner, andreas, , , walker, j. f., wealden beds, pterodactyles in, , ; bones in, , , weight of pterodactyle, whinchat, whitby, , williston, professor w. s., , , , , , willow-wren, wing finger, , , , , , -- membrane, , , , and frontispiece -- metacarpal, ; in dimorphodon, ; in ornithostoma, ; in bats, wings of dragons, winkler, t. c., woodwardian museum, wood-wren, wrist bones, würtemberg, y yale college museum, york museum, , z zittel, karl von, , , , zygomatic arch, printed by william brendon and son plymouth _the century science series_ edited by sir henry e. roscoe, d.c.l., ll.d., f.r.s. charles lyell and modern geology the century science series. edited by sir henry e. roscoe, d.c.l., f.r.s., m.p. * * * * * =john dalton and the rise of modern chemistry.= by sir henry e. roscoe, f.r.s. =major rennell, f.r.s., and the rise of english geography.= by clements r. markham, c.b., f.r.s., president of the royal geographical society. =justus von liebig: his life and work ( - ).= by w. a. shenstone, f.i.c., lecturer on chemistry in clifton college. =the herschels and modern astronomy.= by agnes m. clerke, author of "a popular history of astronomy during the th century," &c. =charles lyell and modern geology.= by rev. professor t. g. bonney, f.r.s. =clerk maxwell and modern physics.= by r. t. glazebrook, f.r.s., fellow of trinity college, cambridge. _in preparation._ =michael faraday: his life and work.= by professor silvanus p. thompson, f.r.s. =humphry davy.= by t. e. thorpe, f.r.s., principal chemist of the government laboratories. =pasteur: his life and work.= by m. armand ruffer, m.d., director of the british institute of preventive medicine. =charles darwin and the origin of species.= by edward b. poulton, m.a., f.r.s., hope professor of zoology in the university of oxford. =hermann von helmholtz.= by a. w. rÜcker, f.r.s., professor of physics in the royal college of science, london. cassell & company, limited, _london; paris & melbourne_ [illustration: hw: charles lyell] _the century science series_ charles lyell and modern geology by prof. t. g. bonney d.sc., ll.d., f.r.s., etc. new york macmillan & co. preface. the life of charles lyell is singularly free from "moving accidents by flood and field." though he travelled much, he never, so far as can be ascertained, was in danger of life or limb, of brigand or beast. at home his career was not hampered by serious difficulties or blocked by formidable obstacles; not a few circumstances were distinctly favourable to success. thus his biography cannot offer the reader either the excitement of adventure, or the interest of an unwearied struggle with adverse conditions. but for all that, as it seems to me, it can teach a lesson of no little value. lyell, while still a young man, determined that he would endeavour to put geology--then only beginning to rank as a science--on a more sound and philosophical basis. to accomplish this purpose, he spared no labour, grudged no expenditure, shrank from no fatigue. for years he was training himself by observation and travel; he was studiously aiming at precision of thought and expression, till "the principles of geology" had been completed and published. but even then, though he might have counted his work done, he spared no pains to make it better, and went on at the task of improvement till the close of his long life. my chief aim, in writing this little volume, has been to bring out this lesson as strongly and as clearly as possible. i have striven to show how charles lyell studied, how he worked, how he accumulated observations, how each journey had its definite purposes. accordingly, i have often given his words in preference to any phrases of my own, and have quoted freely from his letters, diaries, and books, because i wished to show exactly how things presented themselves to his eyes, and how ideas were maturing in his mind. regarded in this light, lyell's life becomes an apologue, setting forth the beneficial results of concentrating the whole energy on one definite object, and the moral grandeur of a calm, judicial, truth-seeking spirit. in writing the following pages i have, of course, mainly drawn upon the "life, letters, and journals," edited by mrs. lyell; but i have also made use of his books, especially the "principles of geology," and the two tours in north america. i am under occasional obligations to the excellent life, contributed by professor g. a. j. cole to the "dictionary of national biography," and have to thank my friend professor j. w. judd for some important details which he had learnt through his intimacy with the veteran geologist. he also kindly lent the engraving (executed in america from a daguerreotype) which has been copied for the frontispiece of this volume. t. g. bonney. contents. chapter page i.--childhood and schooldays ii.--undergraduate days iii.--the growth of a purpose iv.--the purpose developed and accomplished v.--the history and place in science of the "principles of geology" vi.--eight years of quiet progress vii.--geological work in north america viii.--another epoch of work and travel ix.--steady progress x.--the antiquity of man xi.--the evening of life xii.--summary charles lyell and modern geology. chapter i. childhood and schooldays. caledonia, stern and wild, may be called "meet nurse" of geologists as well as of poets. among the most remarkable of the former is charles lyell, who was born in forfarshire on november th, , at kinnordy, the family mansion. his father, who also bore the name of charles,[ ] was both a lover of natural history and a man of high culture. he took an interest at one time in entomology, but abandoned this for botany, devoting himself more especially to the study of the cryptogams. of these he discovered several new species, besides some other plants previously unknown in the british flora, and he contributed the article on lichens to smith's "english botany." more than one species was named after him, as well as a genus of mosses, _lyellia_, which is chiefly found in the himalayas. later in his life, science, on the whole, was supplanted by literature, and he became engrossed in the study of the works of dante, of some of whose poems[ ] he published translations and notes. thus the geologist and author is an instance of "hereditary genius." charles was the eldest of a family of ten--three sons and seven daughters, all of whom grew up. their mother was english, the daughter of thomas smith, of maker hall in yorkshire, "a woman of strong sense and tender anxiety for her children's welfare." "the front of heaven," as lyell has written in a fragment of autobiography, was not "full of fiery shapes at his nativity," but the season was so exceptionally warm that his mother's bedroom-window was kept open all the night--an appropriate birth-omen for the geologist, who had a firmer faith than some of his successors in the value of work in the open air. he has put on record only two characteristics of his infancy, and as these can hardly be personal recollections, we may assume them to have been sufficiently marked to impress others. one if not both was wholly physical. he was very late in cutting his teeth, not a single one having appeared in the first twelvemonth, and the hardness of his infant gums caused an old wife to prognosticate that he would be edentulous. also, his lungs were so vigorous and so habitually exercised that he was pronounced "the loudest and most indefatigable squaller of all the brats of angus." the geologist who so emphatically affirmed the necessity of travel, early became an unconscious practiser of his own precept. when he was three months old his parents went from kinnordy to inveraray, whence they journeyed to the south of england, as far as ilfracombe. from this place they removed to weymouth and thence to southampton. more than a year must have been thus spent, for their second child--also a son--was born at the last-named town. mr. lyell, the father, now took a lease of bartley lodge, on the new forest--some half-dozen miles west of southampton, where the family lived for twenty-eight years. his mother and sisters also left kinnordy, and rented a house in southampton. their frequent excursions to bartley lodge, as lyell observes, were always welcome to the children, for they never came empty-handed. kinnordy, however, was visited from time to time in the summer, and on one of these occasions, when charles was in his fifth year, some of the family had a narrow escape. they were about a stage and a half from edinburgh; the parents and the two boys in one carriage; two nursemaids, the cook, and the two youngest children, sisters, in a chaise behind. the horses of this took fright on a narrow part of the road and upset the carriage over a very steep slope. fortunately all escaped unhurt, except one of the maids, whose arm was cut by the splintered glass. the parents ran to the rescue. "meanwhile, tom and i were left in the carriage. we thought it fine pastime, and i am accused of having prompted tom to assist in plundering the pockets of the carriage of all the buns and other eatables, which we demolished with great speed for fear of interruption."[ ] this adventure, however, was not quite his earliest reminiscence; for that was learning the alphabet when he was about three years old. charles was kept at home till he had nearly completed his eighth year, when he was sent with his brother tom to a boarding-school at ringwood. the master was the rev. r. s. davies; the lads were some fifty in number, the lyells being about the youngest. they seem, however, not to have been ill-treated, though their companions were rather a rough lot, and they were petted by the schoolmaster's daughter. the most sensational incident of his stay at ringwood was a miniature "town and gown" row, a set fight between the lads of the place and of the school, from which, however, the lyells were excluded as too young to share in the joys and the perils of war. but the fray was brought to a rather premature conclusion by the joint intervention of foreign powers--the masters of the school and the tradesmen of the town. in those days smuggling was rife on the south coast, and acting the part of revenue officers and contrabandists was a favourite school game; doubtless the more popular because it afforded a legitimate pretext for something like a fight. the fear of a french invasion also kept this part of england on the _qui vive_, and lyell well remembered the excitement caused by a false alarm that the enemy had landed. he further recollected the mingled joy and sorrow which were caused by the victory of trafalgar and the death of nelson. the brothers remained at ringwood only for about two years, for neither the society nor the instruction could be called first-class; and they were sent, after a rather long holiday at home, to another school of about the same size, but much higher character, in salisbury. the master, dr. radcliffe, an oxford man, was a good classical scholar, and his pupils came from the best families in that part of england. in one respect, the young lyells found it a change for the worse. at ringwood they had an ample playground, close to which was the avon, gliding clear and cool to the sea, a delightful place for a bathe. in a few minutes' walk from the town they were among pleasant lanes; in a short time they could reach the border of the new forest. but at salisbury the school was in the heart of the town, its playground a small yard surrounded by walls, and, as he says, "we only walked out twice or three times in a week, when it did not rain, and were obliged to keep in ranks along the endless streets and dusty roads of the suburbs of a city. it seemed a kind of prison by comparison, especially to me, accustomed to liberty in such a wild place as the new forest." one can sympathise with his feelings, for a procession of schoolboys, walking two and two along the streets of a town, is a dreary spectacle. but an occasional holiday brought some comfort, for then they were sent on a longer excursion. the favourite one was to the curious earthworks of old sarum, then in its glory as a "rotten borough," one alehouse, with its tea-gardens attached, sending two members to parliament. on these excursions more liberty seems to have been permitted. the boys broke up the large flints that lay all about the ground, to find in them cavities lined with chalcedony or drusy crystals of quartz. but the chief interest centred around a mysterious excavation in the earthwork, "a deep, long subterranean tunnel, said to have been used by the garrison to get water from a river in the plain below." to this all new-comers were taken to listen to the tale of its enormous depth and subterranean pool. then, when duly overawed, they felt their hats fly off their heads and saw them rolling out of sight down the tunnel. an interval followed of blank dismay, embittered, no doubt, by dismal anticipations of what would probably happen when they got back to the school-house. then one of the older boys volunteered to act the sybil and lead the way to the nether world. of course they "regained their felt and felt what they regained"--literally, for the hole was dark enough, though we may set down the "many hundred yards" (which lyell says that he descended before he recovered his lost hat) as an instance of the permanent effect of a boyish illusion on even a scientific mind. but the restrictions of salisbury made the liberty of the new forest yet more dear. bartley was an ideal home for boys. it was surrounded by meadows and park-like timber. a two-mile walk brought the lads to rufus stone, and on the wilder parts of the forest. there they could ramble over undulating moors, covered with heath and fern, diversified by marshy tracts, sweet with bog-myrtle, or by patches of furze, golden in season with flowers; or they could wander beneath the shadows of its great woods of oak and beech, over the rustling leaves, among the flickering lights and shadows, winding here and there among tufts of holly scrub, always led on by the hope of some novelty--a rare insect fluttering by, a lizard or a snake gliding into the fern, strange birds circling in the air, a pheasant or even a woodcock springing up almost under the feet. the rabbits scampered to their holes among the furze; a fox now and again stole silently away to cover, or a stag--for the deer had not yet been destroyed--was espied among the tall brake. those, too, it must be remembered, were the days when boys got their holidays in the prime of the summer, at the season of haymaking and of ripe strawberries. they were not kept stewing in hot school-rooms all through july, until the flowers are nearly over and the bright green of the foliage is dulled, until the romance of the summer's youth has given place to the dulness of its middle age. in these days it is our pleasure to do the right thing in the wrong place--a truly national characteristic. we all--young and old--toil through the heat and the long days, and take holiday when the autumn is drawing nigh and nature writes "ichabod" on the beauty of the waning year. at salisbury, lyell had two new experiences--the sorrows of the latin grammar and the joys of a bolster-fight. but his health was not good; a severe attack of measles in the first year was followed in the second by a general "breakdown," with symptoms of weakness of the lungs. so he was taken home for three months to recruit. this was at first a welcome change from the restrictions of salisbury; but, as his lessons necessarily were light, he began to mope for want of occupation; for, as he says, "i was always most exceedingly miserable if unemployed, though i had an excessive aversion to work unless forced to it." so he began to collect insects--a pursuit which, as he remarks, exactly suited him, for it was rather desultory, gave employment to both mind and body, and gratified the "collecting" instinct, which is strong in most boys. he began with the lepidoptera, but before long took an interest in other insects, especially the aquatic. fortunately his father had been for a time a collector, and possessed some good books on entomology, from the pictures in which charles named his captures. this was, of course, an unscientific method, but it taught him to recognise the species and to know their habits. there are few better localities for lepidoptera, as every collector knows, than the new forest, and some of the schoolboy's "finds" afterwards proved welcome to so well known an entomologist as curtis. but when charles returned to school he had to lay aside, for a season, the new hobby; for in those days a schoolboy's interest in natural history did not extend beyond birds'-nesting, and his little world was not less, perhaps even more frank and demonstrative than now, in its criticism of any innovation or peculiarity on the part of one of its members. the school at salisbury appears to have been a preparatory one, so before very long another had to be sought. mr. lyell wished to send his two boys to winchester, but found to his disappointment that there would not be a vacancy for a couple of years; so after instructing them at home for six months, he contented himself with the grammar school at midhurst, in sussex, at the head of which was one dr. bayley, formerly an under-master at winchester. charles, now in his thirteenth year, found this, at first, a great change. the school contained about seventy boys, big as well as little, and its general system resembled that of one of the great public schools. he remarks of this period of his life: "whatever some may say or sing of the happy recollections of their schooldays, i believe the generality, if they told the truth, would not like to have them over again, or would consider them as less happy than those which follow." he was not the kind of boy to find the life of a public school very congenial. evidently he was a quietly-disposed lad, caring more for a country ramble than for games; perhaps a little old-fashioned in his ways; not pugnacious, but preferring a quiet life to the trouble of self-assertion. so, in his second half-year, when he was left to shift entirely for himself, his life was "not a happy one," for a good deal of the primeval savage lingers in the boys of a civilised race. it required, as he said, a good deal to work him up to the point of defending his independence; thus he was deemed incapable of resistance and was plagued accordingly. but at last he turned upon a tormentor, and a fight was the result. it was of homeric proportions, for it lasted two days, during five or six hours on each, the combatants being pretty evenly matched; for though lyell's adversary was rather the smaller and weaker, he knew better how to use his fists. strength at the end prevailed over science, though both parties were about equally damaged. the vanquished pugilist was put to bed, being sorely bruised in the visible parts. lyell, whose hurts were mostly hidden, made light of them, by the advice of friends, but he owns that he ached in every bone for a week, and was black and blue all over his body. still he had not fought in vain, for, though the combat won him little honour, it delivered him from sundry tormentors. the educational system of the school stimulated his ambition to rise in the classes. "by this feeling," he says, "much of my natural antipathy to work, and extreme absence of mind, was conquered in a great measure, and i acquired habits of attention which, however, were very painful to me, and only sustained when i had an object in view." there was an annual speech-day, and charles, on the first occasion, obtained a prize for his performance. "every year afterwards," he continues, "i received invariably a prize for speaking, until high enough to carry off the prizes for latin and english original composition. my inventive talents were not quick, but to have any is so rare a qualification that it is sure to obtain a boy at our great schools (and afterwards as an author) some distinction." evidently he gave proofs of originality beyond his fellows; since he won a prize for english verse, though he had written in the metre of the "lady of the lake" instead of the ordinary ten-syllabic rhyme. on another occasion he commemorated, in his weekly latin copy, the destruction of the rats in a neighbouring pond, writing in mock heroics, after the style of homer's battle of the frogs and mice. the school, like all other collections of boys, had its epidemic hobbies. the game of draughts, coupled unfortunately with gambling on a small scale, was followed by chess, and that by music. to each of these charles was more or less a victim, and his progress up the school was not thereby accelerated. birds'-nesting also had a turn in its season. his love for natural history made him so keen in this pursuit that he became an expert climber of trees. but his schooldays on the whole were uneventful, and he went to oxford at a rather early age, his brother tom having already left midhurst in order to enter the navy. footnotes: [ ] born , died (also son of a charles lyell); educated at st. andrew's and at st. peter's college, cambridge, where he proceeded to the degree of b.a. in and m.a. in . [ ] in , the _canzoniere_, including the _vita nuova and convito_; a second edition was published in ; in a translation of the lyrical poems of dante. [ ] life, letters, and journals, vol. i. p. . chapter ii. undergraduate days. lyell matriculated at exeter college, and appears to have begun residence in january, --that is, soon after completing his eighteenth year. at oxford, though not a "hard reader," he was evidently far from idle, and wrote for some of the university prizes, though without success. several of his letters to his father have been preserved. in these he talks about his studies, mathematical and classical; criticises coleridge's "christabel," and praises kirke white's poetry; describes the fritillaries blossoming in the christchurch meadows, and refers occasionally to political matters. the letters are well expressed, and indicate a thoughtful and observant mind. while yet a schoolboy he had stumbled upon a copy of bakewell's "geology" in his father's library, which had so far awakened his interest that in the earlier part of his residence at oxford he attended a course of professor buckland's lectures, and took careful notes. the new study is briefly mentioned in a letter, dated july th, . this is written from yarmouth, where he is visiting mr. dawson turner, the well-known antiquarian and botanist. he states that, on his way through london, he went to see the elephant at exeter change, bullock's museum, and francillon's collection of insects. at norwich also he saw more insects, the cathedral, and some chalk pits, in which he found an "immense number of belemnites, echinites, and bivalves." he was also greatly interested by the fossils in dr. arnold's collection at yarmouth, particularly by the "alcyonia" found in flints.[ ] a few days later he again dwells on geology, and speculates shrewdly on the formation of the lowland around yarmouth and the ancient course of the river. in one paragraph a germ of the future "principles" may be detected. it runs thus: "dr. arnold and i examined yesterday the pit which is dug out for the foundation of the nelson monument, and found that the first bed of shingle is eight feet down. now this was the last stratum brought by the sea; all since was driven up by wind and kept there by the 'rest-harrow' and other plants. it is mere sand. therefore, thirty-five years ago the deens were nearly as low as the last stratum left by the sea; and as the wind would naturally have begun adding from the very first, it is clear that within fifty years the sea flowed over that part. this, even mr. t. allows, is a strong argument in favour of the recency of the changes. dr. arnold surprised me by telling me that he thought that the straits of dover were formerly joined, and that the great current and tides of the north sea being held back, the sea flowed higher over these parts than now. if he had thought a little more he would have found no necessity for all this, for all those towns on this eastern coast, which have no river god to stand their friend, have necessarily been losing in the same proportion as yarmouth gains--viz. cromer, pakefield, dunwich, aldborough, etc., etc. with dunwich i believe it is _fuit ilium_."[ ] evidently lyell by this time had become deeply interested in geology, for his journal contains several notes made on the road from london to kinnordy, and records, during his stay there, not only the capture of insects, but also visits to quarries, and the discovery of crystallised sulphate of barytes at kirriemuir and elsewhere. towards the end of his first long vacation he travelled, in company with two friends of his own age, from forfarshire across by loch tay, tyndrum, and loch awe, to the western coast at oban, whence they visited staffa and iona. with the caves in the former island he was greatly impressed; and he noted the columns of basalt, which, he said, were "pentagonal" in form, quite different from the "four-square" jointing of the red granite at the south-west end of mull. with the ruins of iona he was a little disappointed, for he wrote in his diary that "they are but poor after all." the wonders of fingal's cave appealed to his poetical as well as to his geological instincts, for in october, after his return to oxford, he sent to his father some stanzas on this subject which are not without a certain merit. but the covering letter was mostly devoted to geology. the next year, , marked an important step in his education as a geologist, for he accompanied his father, mother, and two eldest sisters on a continental tour. starting early in june, they drove in a ramshackle carriage, which frequently broke down, from calais to paris, along much the same route as the railway now takes; they visited the sights of the capital, not forgetting either the artistic treasures of the louvre or the collections of the jardin des plantes, particularly the fossils of the "paris basin." thence they journeyed by fontainebleau and auxerre to dôle, and he makes careful and shrewd notes on the geology, for the carriage travelling of those days, though slow, was not without its advantages--and in crossing the jura he observes the nodular flints in a limestone, and the contrast between these mountains and the grampians of his native land. as they descended the well-known road which leads down to gex in switzerland, they had the good fortune to obtain a splendid view of mont blanc and the alps. from geneva, where he notes the "most peculiar deep blue colour of the rhone," they visited chamouni by the usual route. at this time the principal glaciers were advancing rather rapidly. the glacier des bossons, he remarks, "has trodden down the tallest pines with as much ease as an elephant could the herbage of a meadow. some trunks are still seen projecting from the rock of ice, all the heads being embodied in this mass, which shoots out at the top into tall pyramids and pinnacles of ice, of beautiful shapes and a very pure white.... it has been pressed on not only through the forest, but over some cultivated fields, which are utterly lost."[ ] at chamouni, lyell made the most of his time, for in three days he walked up to the col de balme, climbed the brévent, and made his first glacier expedition, to the well-known oasis among the great fields of snow and ice which is called the jardin. everywhere he notes the flowers, which at that season were in full beauty; and the insects, capturing "no less than seven specimens of that rare insect, _papilio apollo_."[ ] he feels all the surprise and all the delight which thrills the entomologist from the british isles when he first sets foot on the slopes of the higher alps, and sees in abundance the rarities of his own country, besides not a few new species. but lyell does not neglect the rocks and minerals, or the red snow, or the wonders of the ice world. chamouni, we are told, was then "perfectly inundated with english," for fifty arrived in one day. the previous year they had numbered one thousand out of a total of fourteen hundred visitors. since then, times and the village have changed. returning to geneva, the party travelled by lausanne and neuchâtel to bâle, and then followed the picturesque route along the river, by the tumultuous rapids of laufenburg and the grand falls of the rhine, to schaffhausen, whence they turned off to zurich. here he writes of the principal inn that it "partook more than any of a fault too common in switzerland. they have their stables and cow-houses under the same roof, and the unavoidable consequences may be conceived, till they can fall in with a man as able--as 'hercules to cleanse a stable.'" from zurich they crossed the albis to zug. the other members of the party went direct to lucerne, but lyell turned aside to visit the spot where twelve years previously an enormous mass of pudding-stone had come crashing down from the rossberg, had destroyed the village of goldau, and had converted a great tract of fertile land into a wilderness of broken rock. he diagnosed correctly the cause of the catastrophe, and then ascended the rigi. here he spent a flea-bitten night at the kulm hotel, but was rewarded by a fine sunset and a yet finer sunrise. at lucerne he rejoined his relatives, and they drove together over the brünig pass to meyringen. from this place they made an excursion to the giessbach falls, and saw the alpbach in flood after a downpour of rain. this, like some other alpine streams, becomes at such times a raging mass of liquid mud and shattered slate, and lyell carefully notes the action of the torrent under these novel circumstances, and its increased power of transport. parting from his relatives at the handeck falls, he walked up the valley of the aar to the grimsel hospice, where he passed the night, and the next morning crossed over into the valley of the rhone to the foot of its glacier, and then walked back again to meyringen. he remarks that on the way to the hospice "we passed some extraordinary large bare planks of granite rock above our track, the appearance of which i could not account for." this is not surprising, for he had not yet learnt to read the "handwriting on the wall" of a vanished glacier. its interpretation was not to come for another twenty years, when these would be recognised as perhaps the finest examples of ice-worn rocks in switzerland. lyell was evidently a good pedestrian; for the very next day he walked from meyringen over the two scheideggs to lauterbrunnen, ultimately joining his relatives at thun, from which town they went on to berne, where they were so fortunate as to see, from the well-known terrace, the snowy peaks of the oberland in all the beauty of the sunset glow. then they journeyed over the pleasant uplands to vevay, and so by the shore of the lake of geneva and the plain of the rhone valley to martigny, turning aside to visit the salt mines near bex. they reached martigny a little more than seven weeks after the lake, formed in the valley of the dranse by the forward movement of the giétroz glacier, had burst its icy barrier, and they saw everywhere the ruins left by the rush of the flood. the road as they approached martigny was even then, in some places, under water; in others it was completely buried beneath sand. the lower storey of the hotel had been filled with mud and débris, which was still piled up to the courtyard. lyell went up the valley of the dranse to the scene of the catastrophe, and wrote in his journal an interesting description of both the effects of the flood and the remnants of the ice-barrier. before returning to martigny he also walked up to the hospice on the great st. bernard, and then the whole party crossed by the simplon pass into italy, following the accustomed route and visiting the usual sights till they arrived at milan. the next stage on their tour--and this must have been in those days a little tedious--brought them to venice. the campanile lyell does not greatly admire, and of st. mark's he says rather oddly, "the form is very cheerful and gay"; but on the whole he is much impressed with the buildings of venice, and especially with the pictures. on their return they went to bologna, and then crossed the apennines to florence. everywhere little touches in the diary indicate a mind exceptionally observant--such as notes on the first firefly, the fields of millet, the festooned vines seen on the plain, or the peculiar sandy zone on the northern slopes of the hills. he also mentions that shortly after crossing the frontier of tuscany they passed near coviliajo, "a volcanic fire" which proceeded from a neighbouring mountain.[ ] this they intended to visit on their return. but at florence the diary ends abruptly, for the note-book which contained the rest of it was unfortunately lost. we have given this summary of lyell's journal in some detail, but even thus it barely suffices to convey an adequate idea of the cultured tastes, wide interests, and habits of close and accurate observation disclosed by its pages. it shows, better perhaps than any other documents, the mental development of the future author of the "principles of geology." few things, as he journeys, escape his notice; he describes facts carefully and speculates but little. as he wanders among the alpine peaks, he makes no reference to convulsions of the earth's crust; as he views the ruin wrought by the dranse, he says naught of deluges. the travellers got back to england in september, and at the end of the long vacation lyell returned to oxford. there he remained till december, , when he proceeded to the degree of bachelor of arts, obtaining a second class in classical honours. considering that he had never been a "hard reader," and that he appears to have spent much of his "longs" in travel--a practice which, though good for general education, counts for little in the schools--the position indicates that he possessed rather exceptional abilities and a good amount of scholarship. though oxford had been unable to bestow upon him a systematic training in science, she had given a definite bias to his inclination, and had fostered and cultivated a taste for literature which in the future brought forth a rich fruitage. footnotes: [ ] probably they were fossil sponges. [ ] life, letters, and journals, vol. i. p. . [ ] life, letters, and journals, vol. i. p. . [ ] now generally called parnassius apollo; but very likely he captured more than one species of the genus. [ ] probably it was a bituminous shale which had become ignited, as was the case at ringstead bay, dorset, with the kimeridge clay. the same often happens with the "banks" of coal-pits. chapter iii. the growth of a purpose. shortly after he had donned the bachelor's hood lyell came to london, was entered at lincoln's inn, and studied law in the office of a special pleader. science was not forsaken, for in march, , he was elected a fellow of the geological society, and about the same time joined the linnean society. before very long his legal studies were interrupted. his eyes became so weak that a complete rest was prescribed; accordingly, in the autumn of , he accompanied his father on a journey to rome. during this but little was done in geology, for the travellers spent almost all their time in towns. on his return, so far as can be inferred from the few letters which have been published, lyell continued to work at geology, and at christmas, , was seeking in vain for freshwater fossils in the neighbourhood of bartley. in the spring of he investigated the sussex coast from hastings to dungeness, and studied the effects of the sea at winchelsea and rye. in the early summer of he visited the isle of wight, and in a letter to dr. mantell suggested that the "blue marl"[ ] in compton chine is identical with that at folkestone, and compared the underlying strata with those in sussex, clearing up some confusions, into which earlier observers had fallen, about the wealden and lower greensand. he was now evidently beginning to get a firm grip on the subject--a thing far from easy in days when so little had been ascertained--and this year he read his first papers to the geological society--one, in january, written in conjunction with dr. mantell, "on the limestone and clay of the ironsand in sussex"; the other in june, "on the sections presented by some forfarshire rivers." also, on february th, he was elected one of the secretaries of that society, an office which he retained till . this is a pretty clear proof that he had begun to make his mark among geologists, and was well esteemed by the leaders of the science. no sooner had he returned from the isle of wight than he started for paris, going direct from london to calais, in the _earl of liverpool_ steam packet, "in hours! miles! engines horse-power for tons." in the last letter written to his father before quitting england he refers to our neighbours across the channel in the following terms: "my opinion of the french people is that they are much too corrupt for a free government and much too enlightened for a despotic one." that was written full seventy years ago; perhaps even now, were he alive, he would not be disposed to withdraw the words. at paris he was well received by cuvier, humboldt, and other men of science, attended lectures at the jardin du roi, and saw a good deal of society. his letters home often contain interesting references to matters political and social--such as, for example, the following remarks which he heard from the mouth of humboldt: "you cannot conceive how striking and ludicrous a feature it is in parisian society at present that every other man one meets is either minister or ex-minister. so frequent have been the changes. the instant a new ministry is formed, a body of sappers and miners is organised. they work industriously night and day. at last the ministers find that they are supplanted by the very arts by which a few months ago they raised themselves to power."[ ] lyell more than once expresses a regret, which, indeed, was generally felt in scientific circles, that cuvier had lost caste by "dabbling so much with the dirty pool of politics"; and himself works away at geology, studying the fossils of the paris basin in the museums, and visiting the most noted sections in order to add to his own collection and observe the relations of the strata. he returned to england towards the end of september, and no doubt spent the next few months in working at geology as far as his eyes, which were becoming stronger, permitted. the summer of was devoted to geological expeditions. in the earlier part he took mons. constant prévost, one of the leaders of geology in france, to the west of england. their special purpose was to examine the jurassic rocks, but they extended their tour as far as cornwall. afterwards lyell went to scotland, where he was joined by professor buckland; and the two friends, after spending a few days in ross-shire, went to brora, and then returned from inverness by the caledonian canal. this gave them the opportunity of examining the famous "parallel roads" of glenroy, which were the more interesting because they had already seen something of the kind near cowl, in ross-shire. afterwards they went up glen spean and crossed the mountains to blair athol, visiting the noted locality in glen tilt, where hutton made his famous discovery of veins of granite intrusive in the schists of that valley, and then they made their way to edinburgh. here much work was done, both among collections and in the field, and it was lightened--as might be expected in a place so hospitable--by social pleasures and friendly converse with some of the leading literary and scientific men. four years of comparative rest and frequent change of scene had produced such an improvement in the condition of his eyes that he was able to resume his study of the law, and was called to the bar in . for two years he went on the western circuit, having chambers in the temple and getting a little business. but, as his correspondence shows, geology still held the first place in his affections,[ ] and papers were read to the society from time to time. among them one of the most important, though it was not printed in their journal, described a dyke of serpentine which cut through the old red sandstone on the kinnordy estate.[ ] but, as is shown by a letter to his sister, written in the month of november, he had not lost his interest in entomology. at that time the collectors of insects in scotland were very few in number, and the english lepidopterists welcomed the specimens which lyell and his sister had caught in forfarshire. the family had left bartley lodge in the earlier part of the year and had settled in the old home at kinnordy. about this time also lyell began to contribute to the _quarterly review_, writing articles on educational and scientific topics. this led to a friendship with lockhart, who became editor at the end of , and gave him an introduction to sir walter scott. a christmas visit to cambridge introduced him to the social life of that university. in the spring of his ideas as to his future work appear to have begun to assume a definite form. to dr. mantell[ ] he writes that he has been reading lamarck, and is not convinced by that author's theories of the development of species, "which would prove that men may have come from the ourang-outang," though he makes this admission: "after all, what changes a species may really undergo! how impossible will it be to distinguish and lay down a line, beyond which some of the so-called extinct species have never passed into recent ones!" the next sentence is significant: "that the earth is quite as old as he [lamarck] supposes has long been my creed, and i will try before six months are over to convert the readers of the _quarterly_ to that heterodox opinion."[ ] a few lines further on come some sentences which indicate that the leading idea of the "principles" was even then floating in his mind. "i am going to write in confirmation of ancient causes having been the same as modern, and to show that those plants and animals, which we know are becoming preserved now, are the same as were formerly." hence, he proceeds to argue, it is not safe to infer that because the remains of certain classes of plants or animals are not found in particular strata, the creatures themselves did not then exist. "you see the drift of my argument," he continues; "_ergo_, mammalia existed when the oolite and coal, etc., were formed."[ ] the first of these quotations strikes the keynote of modern geology as opposed to the older notions of the science; what follows suggests a caution, to which darwin afterwards drew more particular attention, though he turned the weapon against lyell himself, viz. "the imperfection of the geological record." a letter to his father, also written in the month of april, shows that, while he has an immediate purpose of opening fire on macculloch,[ ] who had bitterly attacked in the _westminster review_ scrope's book upon volcanoes, he has "come to the conclusion that something of a more scientific character is wanted, for which the pages of a periodical are not fitted." he might, he says, write an elementary book, like mrs. marcet's "conversations on chemistry," but something on a much larger scale evidently is floating on his mind. in this letter also he discusses his prospects with his father, who apparently had suggested that he should cease from going on circuit; and argues that he gains time by appearing to be engaged in a profession, for "friends have no mercy on the man who is supposed to have some leisure time, and heap upon him all kinds of unremunerative duties." lyell was not devoid of scotch shrewdness, and doubtless early learnt that when it is all work and no pay men see your merits through a magnifying glass, but when it comes to the question of a reward, they shift the instrument to your defects. gradually the plan of the future book assumed a more definite shape in his mind, as we can see from a letter to dr. mantell early in . about this time also murchison, with whom he was planning a long visit to auvergne,[ ] appears among his correspondents. herschel[ ] tells him how he and faraday had melted in a furnace "granite into a slag-like lava"; hooker[ ] begs him to notice the connection between plants and soils as he travels; his father urges him to take his clerk with him to act as amanuensis and save his eyes, which might be affected by the glare of the sun, and to help him generally in collecting specimens and carrying the barometers. early in the month of may he started for paris, where he met mr. and mrs. murchison, and the party left for clermont ferrand in a "light open carriage, with post horses." as far as moulins the roads were bad, but as they receded from paris and approached the mountains "the roads and the rates of posting improved, so that we averaged nine miles an hour, and the change of horses [was] almost as quick as in england. the politeness of the people has much delighted us, and they are so intelligent that we get much geology from them." clermont ferrand became their headquarters for some time, and lyell's letters to his father are full of notes on the geology of the district, one of the most interesting in europe. the great plateau which rises on the western side of the broad valley of the allier is studded with cones and craters--some so fresh that one might imagine their last eruptions to have happened during the decline of the roman empire;[ ] others in almost every stage of dissection by the scalpels of nature. streams of lava, still rough and clinkery, have poured themselves over the plateau and have run down the valleys till they have reached the plain of the allier, while huge fragments of flows far larger and more ancient have been carved by the action of rain and rivers into natural bastions, and now may be seen resting upon stratified marls, crowded with freshwater shells and other organisms,--the remnants of deposits accumulated in great lakes, which had been already drained in ages long before man appeared on the earth. the two geologists worked hard, for who could be idle in such a country as this? they often began at six in the morning and rested not till evening, though the summers are hot in auvergne, and this one was exceptionally so. lyell writes home, "i never did so much real geology in so many days." mrs. murchison also was "very diligent, sketching, labelling specimens, and making out shells, in which last she is a valuable assistant." sometimes they went farther afield, visiting pontgibaud and the gorge of the sioul, where they found a section previously unnoticed, which gave them a clear proof that a lava-stream had dammed up the course of a river by flowing down into its valley, and had converted the part above into a lake. this again had been drained as the river had carved for itself a new channel, partly in the basalt, partly in the underlying gneiss. here, then, was a clear proof that a river could cut out a path for itself, and that forces still in operation were sufficient, given time enough, to sculpture the features of the earth's crust. notwithstanding the hard work, the outdoor life suited lyell, who writes that his "eyes were never in such condition before." murchison, too, was generally in good health, but would have been better, according to his companion, if he had been a little more abstemious at table and a worse customer to the druggist. from clermont ferrand the travellers moved on to the cantal, where they investigated the lacustrine deposits beneath the lava-streams all around aurillac. these deposits exhibited on a grand scale the phenomena which lyell had already observed on a small one in the marls of the loch at kinnordy. thence they went on through the ardêche and examined the "pet volcanoes of the vivarais," as they had been termed by scrope. the murchisons now began to suffer from the heat, for it was the middle of july. nevertheless, they still pushed on southwards, and after visiting the old towns of gard and the bouches du rhône, went along the riviera to nice, having been delayed for a time at fréjus, where murchison had a sharp attack of malarious fever. it was an exceptionally dry summer, and the town in consequence was malodorous; so after a short halt, they moved on to milan and at last arrived at padua, working at geology as they went along, and constantly accumulating new facts. from padua they visited monte bolca, noted for its fossil fish, the vicentin, with its sheets of basalt, and the euganean hills, where the "volcanic phenomena [were] just auvergne over again." then the travellers parted, the murchisons turning northward to the tyrol, while lyell continued on his journey southward to naples and sicily. some four months had now been spent, almost without interruption, in hard work and the daily questioning of nature. the results had surpassed even lyell's anticipations; they had thrown light upon the geological phenomena of the remote past, and cleared up many difficulties which, hitherto, had impeded the path of the investigators. on the coast of the maritime alps lyell had found huge beds of conglomerate, parted one from another by laminated shales full of fossils, most of which were identical with creatures still living in the mediterranean. these masses attained a thickness of feet, and were displayed in the sides of a valley fifteen miles in length. they supplied a case parallel with that of the conglomerates and sandstones of angus, and indicated that no extraordinary conditions--no deluges or earth shatterings--had been needed in order to form them. if the torrents from the maritime alps, as they plunged into the mediterranean, could build up these masses of stratified pebbles, why not appeal to the same agency in scotland, though the mountains from which they flowed, and the sheet of water into which they plunged, have alike vanished? the great flows of basalt--some fresh and intact, some only giant fragments of yet vaster masses--the broken cones of scoria, and the rounded hills of trachyte in auvergne, had supplied him with links between existing volcanoes and the huge masses of trap with which scotland had made him familiar; while these basalt flows--modern in a geological sense, but carved and furrowed by the streams which still were flowing in their gorges--showed that rain and rivers were most potent, if not exclusive, agents in the excavation of valleys. "the whole tour," thus he wrote to his father, "has been rich, as i had anticipated (and in a manner which murchison had not), in those analogies between existing nature and the effects of causes in remote eras which it will be the great object of my work to point out. i scarcely despair now, so much do these evidences of modern action increase upon us as we go south (towards the more recent volcanic seat of action) of _proving_ the positive identity of the causes now operating with those of former times."[ ] one important result of this journey was a conjoint paper on the excavation of valleys in auvergne, which was written before the friends parted, and was read at the geological society in the later part of the year. lyell writes thus to one of his sisters from rome, on his return thither, in the following january[ ]:-- "my letters from geological friends are very satisfactory as to the unusual interest excited in the geological society by our paper on the excavation of valleys in auvergne. seventy persons present the second evening, and a warm debate. buckland and greenough furious, _contra_ scrope, sedgwick, and warburton supporting us. these were the first two nights in our new _magnificent_ apartments at somerset house." he adds, "longman has paid down _guineas_ to mr. ure, of dublin, for a popular work on geology, just coming out. it is to prove the hebrew cosmogony, and that we ought all to be burnt in smithfield." on the way to naples, lyell made several halts: at parma, bologna, florence, siena, viterbo, and rome; visiting local geologists, studying their collections of fossil shells, keeping his eye more especially on the relations which the species exhibited with the fauna still existing in the mediterranean, and losing no opportunity of examining the ancient volcanic vents and the crater lakes, which form in places such remarkable features in the landscape. "the shells in the travertine," he writes, "are all real species living in italy, so you perceive that the volcanoes had thrown out their ash, pumice, etc., and these had become covered with lakes, and then the valleys had been hollowed out, all before rome was built, , years and more ago." on reaching naples, he climbed vesuvius, and saw for the first time the lava-streams and piles of scoria of a volcano still active; while the wonderful sections of the old crater of somma furnished a link between the living present and the remote past--between italy and auvergne. he visited ischia, where another delightful surprise awaited him, for on its old volcano, monte epomeo, he found, at a height of , feet above the sea, marine shells which belonged "to the same class as those in the lower regions of ischia." they were contained in a mass of clay, and were quite unaltered. this was a great discovery, for the existence of these fossils "had not been dreamt of," and it showed that the land had been elevated to this extent without any appreciable change in the fauna inhabiting the mediterranean. except for this, the island was "an admirable illustration of mont dore." he made an excursion also to the temples of pæstum, wonderful from the weird beauty of their ruins, on the flat plain between the apennines and the sea, but with interest geological as well as archæological, because of the blocks of rough travertine with which their columns are built. these he studied, and he visited the quarries from which they were hewn. his letters frequently contain interesting references to the tyranny of the government, "the inquisitorial suppression of all cultivation of science, whether moral or physical," the idle, happy-go-lucky habits of the common people, the prevalent mendicancy, universal dishonesty, and general corruption. one instance may be worth quoting--it indicates the material with which "united italy " has had to deal. he wanted to pre-pay the postage of a letter to england. the head waiter at his hotel had said to him, "'mind, if it is to england you only pay fifteen grains' (sous). i thought the hint a trait of character, as they are all suspicious of one another. the clerk demanded twenty-five. i remonstrated, but he insisted, and, as he was dressed and had the manners of a gentleman, i paid. when i found on my return that i had been cozened, i asked the head waiter, with some indignation, 'is it possible that the government officers are all knaves?' 'sono napolitani, signor; la sua eccellenza mi scusera, ma io sono romano!'"[ ] the old proverb, what is bred in the bone will out in the flesh, still holds good; but we may doubt whether the standard of virtue is quite so high as the speaker intimated in certain other provinces which piedmont has acquired at the price of the cradle of the royal house and some of the best blood of the nation. at naples, lyell was detained longer than he had expected, waiting for a government steamer. "there was," he says, "no other way of going, for the pirates of tripoli have taken so many neapolitan vessels that no one who has not a fancy to see africa will venture." but he arrived in sicily before the end of november, and succeeded in reaching the summit of etna on the first of december. he was only just in time, for the next day bad weather set in, snow fell heavily, and the summit of the mountain became practically inaccessible for the winter. but as it was, he was able to examine carefully another active volcano, the phenomena of which corresponded with those of vesuvius, though on a grander scale. from nicolosi, where he was delayed a day or two by the weather, lyell went along the catanian plain to syracuse and southward to the extreme point of the island, cape passaro. from this headland he followed the coast westward as far as girgenti, and then struck across the island in an easterly direction till he came within about a day's journey of catania, and then he turned off in a north-westerly direction through the island to palermo. in this zigzag journey, which occupied about five weeks, he succeeded in obtaining a good general knowledge of the geology of the eastern part of the island; he examined many sections and collected many fossils, thus obtaining material for an accurate classification of the little-known deposits of the sicilian lowland, and in addition he lost no opportunity of studying the relations of the volcanic masses, wherever they occurred, to the sedimentary strata. as his letters show, bad roads, poor fare, and miserable accommodation made the journey anything but one of pleasure; but its results, as he wrote to murchison, "exceeded his warmest expectations in the way of modern analogies." by december th he was once more back in the bay of naples. as he returned through rome he availed himself of the opportunity of examining the travertines of tivoli, which, as he remarked, presented more analogies with those of sicily than of auvergne, and welcomed the news that the bones of an elephant had been found in an alluvial deposit which lay beneath the lava of an extinct tuscan volcano. his notes also prove that he was beginning to see his way to the classification of the extensive deposits of sand and marl in italy and sicily, which were subsequently recognised as belonging to the pliocene era. early in february lyell reached geneva on his homeward journey, after crossing the mont cenis, and by the th was back in paris among his geological friends, "pumping them," as he says, and being well pumped in return. some of them, he finds, "have come by most opposite routes to the same conclusions as myself, and we have felt mutually confirmed in our views, although the new opinions must bring about an amazing overthrow in the systems which we were carefully taught ten years ago." the accurate knowledge of deshayes, one of the most eminent conchologists of that day, was especially helpful in bringing his field work in italy and sicily into clear and definite order, and he obtained from him a promise of tables of more than , species of tertiary shells, from which (he writes to his sister caroline, who shared his entomological tastes) "i will build up a system on data never before obtained, by comparing the contents of the present with more ancient seas, and the latter with each other."[ ] by the end of february he is back in london and at the geological society, defending his views on the constancy of nature's operations--views which seemed rank heresy to the older school, who sought to solve every difficulty by a convulsion, and were fettered in their interpretation of the records of geology by supposed theological necessities. in april lyell writes thus to dr. mantel[ ]:-- "a splendid meeting [at the geological society] last night, sedgwick in the chair. conybeare's paper on valley of the thames, directed against messrs. lyell and murchison's former paper, was read in part. buckland present to defend the 'diluvialists,' as conybeare styles his sect; and us he terms 'fluvialists.' greenough assisted us by making an ultra speech on the importance of modern causes.... murchison and i fought stoutly, and buckland was very piano. conybeare's memoir is not strong by any means. he admits three deluges before the noachian! and buckland adds god knows how many _catastrophes_ besides; so we have driven them out of the mosaic record fairly." again, in the month of june, he writes to the same correspondent in regard to the second portion of the same paper[ ]:-- "the last discharge of conybeare's artillery, served by the great oxford engineer against the fluvialists, as they are pleased to term us, drew upon them on friday a sharp volley of musketry from all sides, and such a broadside, at the finale, from sedgwick as was enough to sink the 'reliquiæ diluvianæ'[ ] for ever, and make the second volume shy of venturing out to sea." in a third letter, written to dr. fleming, he gives a similar account of the battle between the diluvialists and fluvialists, and concludes with these words[ ]:-- "i am preparing a general work on the younger epochs of the earth's history, which i hope to be out with next spring. i begin with sicily, which has almost entirely risen from the sea, to the height of nearly , feet, since all the present animals existed in the mediterranean!" footnotes: [ ] now recognised as gault. the identification named above was soon found to be correct. [ ] life, letters, and journals, vol. i. p. . some sentences (for the sake of brevity) are omitted from the quotation. [ ] he was also elected a fellow of the royal society in . [ ] it appeared in the _edin. journ. sci._, iii. ( ) p. , being his first actual publication. its importance consisted in proving that serpentine was, or rather had been, an igneous rock. if proper attention had been paid to it, fewer mistaken statements and hypotheses would have attained the dignity of appearing in print. [ ] dr. gideon a. mantell, a surgeon by profession, at that time resident in lewes, who made valuable contributions to the geology of south-east england, and was also distinguished for his popular lectures and books. he died in . [ ] probably referring to an article on scrope's "geology of central france," in which he shows that he fully accepted the huttonian doctrine of interpreting the geology of past ages by reference to the causes still at work. it appeared in the _quarterly review_, oct. , vol. xxxvi. p. . [ ] life, letters, and journals, vol. i. p. . [ ] dr. john macculloch, author (among other works) of the "highlands and western isles of scotland." he was an excellent geologist on the mineralogical side, but had little sympathy with palæontology or with the views to which lyell inclined. he died in . [ ] this district had been already explored by mr. g. p. scrope, the first edition of whose classic work, "the volcanoes of central france," was published in . [ ] sir john f. w. herschel, the second of the illustrious astronomers of that name. [ ] sir w. j. hooker. [ ] certain passages in a letter of sidonius apollinaris, bishop of clermont, dated about a.d., and in the works of alcimus avitus, archbishop of vienne, about half a century later, have been interpreted as referring to volcanic eruptions somewhere in auvergne. this, however, is disputed by many authorities. (see _geological magazine_, , p. .) [ ] life, letters, and journals, vol. i. p. . [ ] life, letters, and journals, vol. i. p. . [ ] life, letters, and journals, vol. i. p. . [ ] life, letters, and journals, vol. i. p. . [ ] _ibid._ [ ] _ut suprà_, p. . [ ] "reliquiæ diluvianæ, or observations on organic remains contained in caves, fissures, and diluvial gravel, and on other geological phenomena attesting the action of an universal deluge." by professor buckland. . [ ] _ut suprà_, p. . chapter iv. the purpose developed and accomplished. the summer of was spent at kinnordy, when the quarries of kirriemuir and the neighbouring districts were visited from time to time, the workmen being encouraged to look out for the remains of plants and the scales of fishes. murchison, however, was again travelling on the continent, and, in company with sedgwick, was exploring the geological structure of the eastern alps and the basin of the danube. they appear to have kept up communication with lyell, who hears with satisfaction of the results of their work, since these cannot fail to keep murchison sound in the uniformitarian faith and to complete the conversion of sedgwick.[ ] "the latter" (lyell writes to dr. fleming) "was astonished at finding what i had satisfied myself of everywhere, that in the more recent tertiary groups great masses of rock, like the different members of our secondaries, are to be found. they call the grand formation in which they have been working sub-apennine. vienna falls into it. i suspect it is a shade older, as the sub-apennines are several shades older than the sicilian tertiaries. they have discovered an immensely thick conglomerate, feet of compact marble-like limestone, a great thickness of oolite, not distinguishable from bath oolite, an upper red sand and conglomerate, etc. etc., all members of that group zoologically sub-apennine. this is glorious news for me.... it chimes in well with making old red transition mountain limestone and coal, and as much more as we can, _one epoch_, for when nature sets about building in one place, she makes a great batch there.... all the freshwater, marine, and other groups of the paris basin are one epoch, at the farthest not more separated than the upper and lower chalk." a letter to the same correspondent, written nearly three weeks later, at the end of october, and after his return to london, refers to the consequences of this journey.[ ] "sedgwick and murchison are just returned, the former full of magnificent views. throws overboard all the diluvian hypothesis; is vexed he ever lost time about such a complete humbug; says he lost two years by having also started a wernerian. he says primary rocks are not primary, but, as hutton supposed, some igneous, some altered secondary. mica schist in alps lies _over_ organic remains. no rock in the alps older than lias.[ ] much of buckland's dashing paper on alps wrong. a formation (marine) found at foot of alps, between danube and rhine, thicker than all the english secondaries united. munich is in it. its age probably between chalk and our oldest tertiaries. i have this moment received a note from c. prévost by murchison. he has heard with delight and surprise of their alpine novelties, and, alluding to them and other discoveries, he says: 'comme nous allons rire de nos vieilles idées! comme nous allons nous moquer de nous-mêmes!' at the same time he says: 'if in your book you are too hard on us on this side the channel, we will throw at you some of old brongniart's "metric and peponary blocks" which float in that general and universal diluvium, and have been there "depuis le grand jour qui a separé, d'une manière si tranchée, les temps ante-des-temps post-diluviens."'" a short time afterwards, in a letter addressed to mr. leonard horner, lyell declines to become a candidate for the professorship of geology and mineralogy at the london university,[ ] which was first opened in the autumn of the previous year. evidently he considers himself to be too fully occupied, for he writes to dr. mantell on december th that his book has taken a definite shape.[ ] "i am bound hand and foot. in the press on monday next with my work, which murray is going to publish-- vols.--the title, 'principles of geology: being an attempt to explain the former changes of the earth's surface by reference to causes now in operation.' the first volume will be quite finished by the end of the month. the second is, in a manner, written, but will require great recasting. i start for iceland by the end of april, so time is precious." the process of incubation was continued throughout the winter. on february rd, , he had corrected the press as far as the eightieth page, getting on slowly, but with satisfaction to himself. "how much more difficult it is," he remarks, "to write for general readers than for the scientific world; yet half our _savants_ think that to write _popularly_ would be a condescension to which they might bend if they would." he fully expects that the publication of his book will bring a hornet's nest about his head, but he has determined that, when the first volume is attacked, he will waste no money on pamphleteering, but will work on steadily at the second volume, and then, if the book is a success, at the second edition, for "controversy is interminable work." he felt now that the facts of nature were on his side, and his conclusions right in the main; so, like most strong men, he adopted the same course as did the founder of marischal college, aberdeen, and wrote over the door of his study, "lat them say." the plan of a summer tour in iceland fell through; so did another for a long journey from st. petersburg by moscow to the sea of azof, to be followed by an examination of the crimea and the great steppe, and a return up the danube to vienna; but by the middle of june the first volume of the "principles" was nearly finished; and in a letter to scrope,[ ] to whom advance sheets of the book had been forwarded, in order that he might review it in the _quarterly_, lyell explains concisely the position which he has taken in regard to cosmology and the earth's history. "probably there was a beginning--it is a metaphysical question, worthy a theologian--probably there will be an end. species, as you say, have begun and ended--but the analogy is faint and distant. perhaps it is an analogy, but all i say is, there are, as hutton said, 'no signs of a beginning, no prospect of an end.' herschel thought the nebulæ became worlds. davy said in his last book, 'it is always more probable that the new stars become visible, and then invisible, and pre-existed, than that they are created and extinguished.' so i think. all i ask is, that at any given period of the past, don't stop inquiry when puzzled by refuge to a beginning, which is all one with 'another state of nature,' as it appears to me. but there is no harm in your attacking me, provided you point out that it is the proof i deny, not the probability of a beginning. mark, too, my argument, that we are called upon to say in each case, 'which is now most probable, my ignorance of all possible effects of existing causes,' or that 'the beginning' is the cause of this puzzling phenomenon?" in other parts of the letter he refers to his theory of the dependence of the climate of a region upon the geography, not only upon its latitude, but also upon the distribution of land and sea, and that of the coincidence of time between zoological and geographical changes in the past, as the most novel parts of the book; stating also that he has been careful to refer to all authors from whom he has borrowed, and that to scrope himself he is under more obligation, so far as he knows, than to any other geologist. the concluding words also are interesting:-- "i conceived the idea five or six years ago, that if ever the mosaic geology could be set down without giving offence, it would be in an historical sketch, and you must abstract mine in order to have as little to say as possible yourself. let them feel it, and point the moral." the last-named difficulty, to which lyell refers in another part of this letter, was undoubtedly one of the most formidable "rocks ahead" in the path of his new book. up to that time the progress of geology had been most seriously impeded by the supposed necessity of making its results harmonise with the mosaic cosmogony. it was assumed as an axiom that the opening chapters of genesis were to be understood in the strict literal sense of the words, and that to admit the possibility of misconceptions or mistakes in matters wholly beyond the cognisance of the writers, was a denial of the inspiration of scripture, and was rank blasphemy. a large number of persons--among whom are the great mass of amateur theologians, together with some experts--are always very prone to assume the meaning of certain fundamental terms to be exactly that which they desire, and then to proceed deductively to a conclusion as if their questionable postulates were axiomatic truths. they further assume, very commonly, that the possession of theological knowledge--scanty and superficial though it may be--enables them to dispense with any study of science, and to pronounce authoritatively on the value of evidence which they are incapable of weighing, and of conclusions which they are too ignorant to test. being thus, in their own opinion, infallible, a freedom of expression is, for them, more than permissible, which, in most other matters, would be generally held to transgress the limits of courtesy and to trespass on those of vituperation. lyell had perceived that little real progress could be made till geologists were free to look facts in the face and to follow their guidance to whatever conclusions these might lead, irrespective of supposed consequences; or that, in other words, questions of science must be settled by inductive reasoning from accurate observations, and not by an appeal to the opinions of the men of olden time, however great might be the sanctity of their characters or the honour due to their memories. wisely, however, he determined to prefer an indirect to a direct method of attack, and to avoid, so far as was possible, giving needlessly any cause of offence by abruptness of statement or by intemperance of language. in deluges, the favourite resort of every "catastrophic" geologist, lyell had long lost faith, and he laughs in one of his letters at the idea of a french geologist, that a sudden upheaval of south america may have been the cause of the noachian flood. to the breaks in the succession of strata, a fact upon which the catastrophists much relied, he attached comparatively little value, insisting on their more or less local character. in the records of the rocks he finds no trace of a clean sweep of living creatures or of anything like a general clearance of the earth's surface, and no corroboration of the mosaic cosmogony. he is bent on interpreting the work of nature in the past by the work of nature in the present, and not by the writings of the fathers, or even by the words of scripture itself. some time in the month of june the last sheet of the "principles" must have been sent to press; for on the th of that month lyell writes from havre on his way to bordeaux, through part of normandy, brittany, and la vendée. this journey took him, as he says, "through some of the finest countries and most detestable roads he ever saw." on this occasion he was accompanied by a captain cooke, a commander in the royal navy; a man well informed, acquainted with spain (the end of their journey), a botanist, and not wholly ignorant of geology--in short, an excellent companion, whose only fault was being "a little too fond of lagging a day for rest," even in places where nothing is to be done. writing from bordeaux to a sister, lyell expresses a hope that at bagnères de luchon he may hear whether his book is out.[ ] two passages in his letter are not without a more general interest. one repeats a remark made to him by d'aubuisson, whom he describes as "a great gun of the old wernerian school, who ... thinks the interest of the subject greatly destroyed by our new innovation, especially our having almost cut mineralogy and turned it into a zoological science."[ ] d'aubuisson also said, "we _catholic_ geologists flatter ourselves that we have kept clear of the mixing of things sacred and profane, but the three great protestants, de luc, cuvier, and buckland, have not done so; have they done good to science or to religion? no, but some say they have to themselves by it." the other remark is interesting in its reference to french politics, seeing that it is dated on the th of july, . it runs thus[ ]:-- "the quiet and perfect order and calmness that reigned at bourbon, vendée, and bordeaux and toulouse during the heat of the elections, afford a noble example to us--never were people in a greater state of excitement on political grounds than the french at this moment, yet never in our country towns were assizes conducted with more seriousness and quiet. there is no occasion to make the rabble drunk. all the voters of the little colleges are of the rank of shopkeepers at least, those of the highest are gentlemen--only , of them out of the millions of french. they are too many for such jobbing as in a scotch county, and too independent and rich to have the feelings of a mob." yet at the end of this month came the "three days of july"; "perfect order and calmness" were at an end; charles x. abdicated the throne, and the bourbons again became exiles from france. from toulouse lyell and his companion journeyed by the banks of the ariège to the picturesque old town of foix, and from this place to ax, a watering-place on one of the tributaries to that river, in the heart of the pyrenees. his keen eye notes at once the difference between the scenery of this chain and that of the alps. apart from the different character of the vegetation--the more luxuriant flora, the extensive forests of beech and oak at elevations where in switzerland only the pines and larches would flourish--the valleys are narrower, the mountains more precipitous--the scenery, in short, is more like that around interlaken or in the valley of lauterbrunnen, without the lakes of the one or the grand background of snowy peaks in the other. in the pyrenees the inferior height and the more southern position of the chain diminishes the snowfields and curtails the glaciers, so that the torrents run with purer waters, like they do in the alps about the birthplace of the po. in order to acquire a clear idea of the structure of the pyrenees the travellers crossed from ax to the southern side of the watershed, though they still remained on french territory; for here, in the neighbourhood of andorre, the frontier cuts off the heads of one or two valleys which geographically form part of spain. into this country they had purposed to descend, but the obstacles interposed by the reactionary jealousy of local dogberries and the possible risks from political complications were so great, that they judged it wiser to abandon the attempt. so the travellers separated for a time, captain cooke, who feared the heat of the lower country, going eastwards through the curious little mountain republic of andorre to luchon; while lyell, who seems to have been proof against the sun, recrossed the watershed into the valley of the tet and descended it to perpignan. information obtained in this town encouraged him to go direct to barcelona, where the captain-general, the conde d'espagne, a distinguished soldier and diplomatist, gave him a courteous reception, and did everything in his power to smooth the way for a visit to olot, a region of extinct volcanoes, which had been one of the chief ends of lyell's journey. the expedition was successful; he did not fall among thieves, and was only annoyed by the tedious formalities and petty impertinences of the local functionaries of northern spain; and he returned to france by a pass on the eastern side of the canigou. he was not a little astonished, as might be expected from the remarks already quoted, when he found on arriving in that country that the reign of the bourbons and the priests was over, the tricolor flag was hoisted on all the churches, and the royalist officials had been replaced by the nominees of the national government. the visit to olot amply repaid him for the toil and trouble of the journey. an account of the district was inserted in the concluding volume of the "principles," which was afterwards incorporated into the "elements of geology." the following summary is quoted from a letter to scrope, who had suggested the visit, which was written from luchon, where he arrived a few days after his return into france[ ]:-- "like those of the vivarais [the volcanoes of catalonia] are all, both cones and craters, subsequent to the existence of the actual hills and dales, or, in other words, no alteration of previously existing levels accompanied or has followed the introduction of the volcanic matter, except such as the matter erupted necessarily occasioned. the cones, at least fourteen of them mostly with craters, stand like monpezat, and as perfect; the currents flow down where the rivers would be if not displaced. but here, as in the vivarais, deep sections have been cut through the lava by streams much smaller in general, and at certain points the lava is fairly cut through, and even in two or three cases the subjacent rock. thus at castel follet, a great current near its termination is cut through, and eighty or ninety feet of columnar basalt laid open, resting on an old alluvium, not containing volcanic pebbles; and below that, nummulitic limestone is eroded to the depth of twenty-five feet, the river now being about thirty-five feet lower than when the lava flowed, though most of the old valley is still occupied by the lava current. there are about fourteen or perhaps twenty points of eruption without craters. in all cases they burst through secondary limestone and sandstone, no altered rocks thrown up, as far as i could learn, not a dike exposed. a linear direction in the cones and points of eruption from north to south. until some remains of quadrupeds are found, or other organic medals found, no guess can be made as to their geological date, unless anyone will undertake to say when the valleys of that district were excavated. as to historical dates, that is all a fudge ... i can assure you that there never was an eruption within memory of man." at luchon lyell rejoined captain cooke, and they visited one or two interesting spots in the more western part of the pyrenees, such as the cirque de gavarnie and the brèche de roland. the former would afford object-lessons on the erosive action of cascades; the latter would set him speculating on the causes which could have fashioned that strange portal in the limestone crest of the mountain. they descended some distance on the spanish side of the brèche, in order to make a more complete investigation of the structure of the chain, sleeping at a shepherd's hut and returning across the snowfields next day. it is evident that whenever there was a hope of securing any geological information or of seeing some remarkable aspect of nature, lyell was almost insensible either to heat or to fatigue. towards the middle of september he had reached bayonne, from which place another very interesting letter is despatched to scrope.[ ] in this he gives suggestions for making a number of experiments in order to produce by artificial means such rock-structures as lamination, ripple-mark, and current-bedding, and describes briefly a series of observations bearing on these questions, which had been carried out both during his late journey and on other occasions. "i have," he says, "for a long time been making minute drawings of the lamination and stratification of beds, in formations of very different ages, first with a view to prove to demonstration that at every epoch the same identical causes were in operation. i was next led in scotland to a suspicion, since confirmed, that all the minute regularities and irregularities of stratification and lamination were preserved in primary clay-slate, mica-slate, gneiss, etc., showing that they had been subjected to the same general and even accidental circumstances attending the sedimentary accumulation of secondary and fossil-bearing formations.[ ] lastly, i came to find out that all these various characters were identical with those presented by the bars, deltas, etc., of existing rivers, estuaries, etc." early in october lyell is back again in paris, to find louis philippe seated on the throne in the place of charles x., and a war party "praying night and day for the entry of the prussians into belgium in the hope of the french being drawn into the affair. a finer opportunity, they say, could not have happened for resuming our natural limits on the rhine." in the midst of political changes and warlike aspirations geology, he observes, is not making much progress in paris. some of the naturalists have "got their heads too full of politics"; others are forced to work as literary hacks in order to live. "books on natural history and medicine have no sale; there is a demand only for political pamphlets." so lyell enters into an engagement with deshayes, who, like so many others, has to live by his pen lest he should starve by science, for "a private course of fossil conchology," and for two months' work after lyell has returned to england, to be spent in tabulating the species of tertiary shells in his own (deshayes') and the other great collections of paris. "i shall thus," lyell says, "be giving the subject a decided push by rendering the greater wealth of the french collectors available in illustrating the greater experience of the english geologists in actual observation; for here they sit still and buy shells, and work indoors, as much as we travel." he also remarks to the same correspondent (a sister): "i am nearly sure now that my grand theory of temperature will carry the day.... i will treat our geologists with a theory for the newer deposits in next volume, which, although not half so original, will perhaps surprise them more."[ ] he was expecting, as another letter shows, to prove the gradual approximation of the fauna preserved in the tertiary deposits to that which still exists, and to settle, as he hopes "for ever, the question whether species come in all at a batch or are always going out and coming in." already he is in a position to affirm that the tertiary formations of sicily in all probability are more recent than the "crags" of england, for, among the sixty-three species which he had collected from the beds underlying etna, only three were not known to be still inhabitants of the mediterranean; and besides this, between these "crags" and the london clay a series of formations can be intercalated. in the same letter (to scrope)[ ] he states that deshayes has found, at st. mihiel on the meuse, three old needles of limestone, like those in the isle of wight, round which run three distinct lines of perforations, like those on the columns of the "temple of serapis;" these hollows being "sometimes empty, but thousands of them filled with saxicavas." this, of course, was a proof that there had been, in comparatively recent times, important changes in the level of the land and sea. early in november lyell is back in london, at his chambers in crown office row, temple, to find that scrope's review of the first volume of the "principles" has been much admired, that the book is selling steadily, and is likely to prove "as good as an annuity"; that it has not been seriously attacked by the "diluvialists," while it has been highly praised by the bulk of geologists. he is about to move, he writes, into chambers in raymond buildings, gray's inn, which are "very light, healthy and good, on the same staircase as broderip." invitations to dinner are becoming frequent, but he wisely determines to go but little into society. "all my friends," he says, "who are in practice do this all the year and every year, and i do not see why i should not be privileged, now that i have the moral certainty of earning a small but honourable independence if i labour as hard for the next ten years as during the last three. i was never in better health, rarely so good, and after so long a fallow i feel that a good crop will be yielded and that i am in good train for composition."[ ] the second volume, he hopes, will be out in six months; this will include the history of the globe to the beginning of the tertiary era, when the first of existing species appeared. the next year, , was an epoch marked by more than one change. to take the smallest first, he was made a deputy-lieutenant of the county of forfar; next, in march, he was elected professor of geology at king's college, london, which had been recently founded by members of the church of england as an educational counterpoise to the university of london (university college). to lyell himself the appointment was comparatively unimportant, but it indicated that wider views on scientific questions and a more tolerant spirit were gaining ground among the higher ranks of the clergy in the established church. the appointment was in the hands, exclusively, of the archbishop of canterbury, the bishops of london and of llandaff, and two "strictly orthodox doctors." llandaff, lyell was informed, hesitated, but conybeare,[ ] though opposed to lyell's theories, vouched for his orthodoxy. so the prelates declared that they "considered some of my doctrines startling enough, but could not find that they were come by otherwise than in a straight-forward manner, and (as i appeared to think) logically deducible from the facts; so that whether the facts were true or not, or my conclusions logical or otherwise, there was no reason to infer that i had made my theory from any hostile feeling towards revelation"[ ]--a conclusion, marked by a wise caution, which representatives of the church of england would have done well to bear in mind on more than one subsequent occasion--such as, for example, when the question of the antiquity of man or that of the origin of species was raised. but supporters of the church of england may fairly maintain that in difficult crises, especially in those connected with discoveries in science or in history, the utterances of her bishops have been generally cautious and far-seeing; displays of confident ignorance and rash denunciations are more common among the "inferior clergy." as a comment on the moderation indicated by his election, lyell says that a friend in the united states affirms that there "he could hardly dare to approve of the doctrines even in a review, such a storm would the orthodox raise against him. so much for toleration of church establishment and no church establishment countries." a third event of the year--which also happened in the earlier part of it--was destined to exercise a much more lasting influence upon his life. this was his engagement to miss mary horner, eldest daughter of mr. leonard horner, the younger and hardly less distinguished brother of francis horner, who, while almost as enthusiastic a geologist as his future son-in-law, took an active interest in educational questions, and afterwards did public service as inspector of factories. by the middle of june lyell had advanced as far as page in printing the second volume of the "principles of geology," notwithstanding interruptions, such as a visit to cambridge, where he took an _ad eundem_ degree,[ ] and the presence of his father and brother, as well as of his friend conybeare, in london, all of whom required to be lionised. the letter[ ] (to mantell) which refers to these impediments, passes abruptly from fitton's broken arm to the giant femur of a new reptile, and incidentally mentions the discovery of a section which has since become a centre of geological controversy. "murchison and his wife," he writes, "are gone to make a tour in wales, where a certain trimmer has found near snowdon 'crag' shells at a height of , feet, which buckland and he convey thither by the deluge." the shells are at an altitude above sea-level considerably higher than lyell supposed. moel tryfaen is a massive, rather outlying hill, about five miles west of the peak of snowdon, and at about the same distance from the nearest part of the sea-coast. its bare summit rises gently to a scattered group of projecting crags, the highest of which is , feet above the sea. on the eastern side are extensive slate quarries, and in working these the shell beds are disclosed a short distance below the summit. they consist of well-stratified sands, with occasional gravelly beds, and contain a fair number of shells, both broken and whole, the fauna being slightly more arctic than that which still inhabits the neighbouring sea. the deposit is now recognised as more recent than the "crags" of east anglia, for none of the species are extinct, and is assigned to some part of the so-called glacial epoch. it was before long regarded as an indication that, at no very remote date after north wales had assumed or very nearly assumed its present outlines, the whole district was depressed for at least , feet, so that the sea broke over the summit crags of moel tryfaen. for many years this interpretation passed unquestioned; but a modern school of geologists has found it to be such an inconvenient obstacle to certain hypotheses about the former extent of land-ice, that they maintain these shells were collected from the bed of the irish sea (then supposed to be above water) by an ice-sheet as it was on its way from the north to invade the principality, and were conveyed by it, with all care, up the slopes of moel tryfaen, till they were finally deposited on its summit, in beds which somehow or other were stratified. one may venture to doubt whether the hypothesis of a rampant and conchologically-disposed ice-sheet would have found much more favour with the cautiously inductive mind of lyell than that of a deluge. shortly after this letter, lyell, though all the manuscript of his second volume had not yet been sent to the printers, and proof-sheets followed him, refreshed himself with a tour of four or five weeks in the volcanic district of the eifel. here the cones, all comparatively low, are scattered sporadically over a rolling upland which occupies the angle between the rhine and the moselle. the valleys for the most part are carved out of slaty rocks much of the same age as those of devonshire; and the craters, "strange holes, each eruption having been almost invariably at some new point," are now very commonly occupied by quiet pools of water, such as lyell had already seen in the old volcanic districts of the papal states. among these craters, composed sometimes of loose and light scoria, from which no lava-stream ever flowed, he found fresh evidence--as at the rotherberg--against the diluvian hypothesis. "it is," as he writes to his friend, dr. fleming, "one of the ten thousand proofs of the incubus that the mosaic deluge has been, and is, i fear, long destined to be, on our science. now, i am fully determined to open my strongest fire against the new diluvial theory of swamping our continents by waves raised by paroxysmal earthquakes. i can prove by reference to cones (hundreds of uninjured cones) of loose volcanic scoriæ and ashes, of various and some of great antiquity (as proved by associated organic remains), that no such general waves have swept over europe during the tertiary era--cones at almost every height, from near the sea, to thousands of feet above it."[ ] but early in august he was back in london, hard at work in writing and correcting proofs. this business detained him longer than he anticipated, but his labours were cheered by the news of the eruption of graham's island. here was another case in support of the thesis which he was ready to maintain against all comers. but a few months since there had been a depth of eighty fathoms, as was proved by sounding, on the site of this island. now the cone "is feet above water and is still growing.[ ] here is a hill feet, with hope of more, and the probability of much having been done before the 'britannia' sounded." surely nature herself was testifying "her approbation of the advocates of modern causes! was the cross which constantine saw in the heavens a more clear indication of the approaching conversion of a wavering world?" but in the beginning of september lyell broke away from the emissaries of the press and took passage by sea to edinburgh, there to combine business with a fair amount of both scientific work and social pleasure. this visit afforded him an opportunity of hearing chalmers preach. in a letter to miss horner he gives a brief abstract, and expresses his general opinion of the sermon[ ]:-- "it was a very long discourse, but admirable. the subject was 'repentance,' a hackneyed one enough.... he explained the effect of habit, and its increasing power over the mind, as a law of our nature, with as much clearness and as philosophically as he could have done had he been explaining the doctrine to a class of university students in a lecture on the philosophy of the human mind. but then the practical application was enforced by a strain of real eloquence, of a very energetic, natural, and striking description.... but, unfortunately, every here and there he seemed to feel that he was sinning against some of the calvinistic doctrines of his school, and all at once there was some dexterous pleading about 'original sin,' which interfered a little with the free current of the discourse.... upon the whole, however, judging from this single specimen, i think i would sooner hear him again than any preacher i ever heard, reginald heber not excepted." at this time lyell was keeping a journal, which was forwarded to miss horner, then in germany, to serve apparently as a substitute for ordinary letters; home news, disturbances arising from the struggle over the reform bill, visits of friends, geological researches, walks on the hills to search for plants or for insects, the habits of the kinnordy bees, or the accomplishments of two parrots, brought from africa by his naval brother--all being jotted down just as they occurred. among this _farrago_--though not of nonsense--geological topics, since miss horner had similar tastes, occupy a considerable space. she, however, evidently was, comparatively speaking, a beginner, and in one or two characteristic sentences her lover and preceptor passes from information to counsel: "if you are not frightened by de la beche, i think you are in a fair way to be a geologist; though it is in the field only that a person can really get to like the stiff part of it. not that there is really anything in it that is not very easy, when put into plainer language than scientific writers choose often unnecessarily to employ." he also records[ ] a piece of advice from his old friend, dr. fleming, which is enough to make a modern professor of geology sigh for "the good old times." he said to lyell: "if you lecture once a year for a short course, i am sure you will derive advantage from it. a short practice of lecturing is a rehearsal of what you may afterwards publish, and teaches you by the contact with pupils how to instruct, and in what you are obscure. a little of this will improve your power, perhaps as an author. then, as you are pursuing a path of original and purely independent discovery and observation, it increases much your public usefulness in a science so unavoidably controversial to have thrown over you the _moral protection_ of being in a public and responsible situation, connected with a body like king's college. but then you must stipulate that you are to be free to travel, and must only be bound to give one short course annually." truly those must have been halcyon days for professors! the journal also proves, by its brief account of a scotch festival, which accords with little hints dropped elsewhere in it or in letters, that our forefathers, not wholly excluding men of science, some sixty years ago habitually consumed much more "strong drink" than would be considered correct at the present day:-- "it was just an angus set-to of the old _régime_. they arrived at half-past six o'clock and waited dinner one hour. gentlemen rejoined the ladies at half-past twelve o'clock! they, in the meantime, had had tea, and a regular supper laid out in the drawing-room. after an hour with the ladies they returned to the dining-room to supper at half-past one o'clock, and my father left them at half-past two o'clock! the ladies did not go to _this_ supper." the journal, in short, like the well-known scotch dish, affords a great deal of "confused feeding" of a pleasant sort, but no samples of love-making. the nearest approach to it is in the following passage, which is worth quoting, not for that reason, but as incidentally disclosing the strength of the author's character:-- "i shall write a few words before i get into the steamboat just to tranquillise my mind a little, after reading several controversial articles by elie de beaumont and others against my system. if i find myself growing too warm or annoyed at such hostile demonstrations i shall always retreat to you. you will be my harbour of peace to retire to, and where i may forget the storm. i know that by persevering steadily i shall some years hence stand very differently from where i now am in science; and my only danger is the being impatient, and tempted to waste my time on petty controversies and quarrels about the priority of the discovery of this or that fact or theory."[ ] friends in plenty were awaiting him in london, which was reached about the first of november: the murchisons and somervilles, broderip, curtis, basil hall, and hooker, with necker from switzerland, and many more. he is also cheered by finding that his ideas are steadily gaining ground among geologists, converts becoming more confident, unbelievers more uneasy. he made good progress with his book, and realised, before the end of the year, that his materials could not be compressed into a single volume; so he determined to issue the part already completed as a second volume, and to finish the work in a third. from time to time the diary contains references to a recent contest for the presidency of the royal society, and to political matters such as the reform bill; but, though in favour of the latter, he is not very enthusiastic on the subject, for on one occasion he expresses regret at having been absent, through forgetfulness, from a meeting of the geographical society, where he would have "got some sound information instead of hearing politicians discuss the interminable bill." the lectures at king's college evidently weighed upon his mind as they drew near, and he was not stirred to enthusiasm by the prospect of teaching; for towards the close of the year he more than once debated with his friends the question whether or no he should retain the appointment. murchison was in favour of resignation; conybeare took the opposite view. of his advice lyell remarks, "the fact is, conybeare's notion of these things is what the english public have not yet come up to, which, if they had, the geological professorship in london would be a worthy aim for any man's ambition, whereas it is now one that the multitude would rather wonder at one's accepting."[ ] the british public apparently still lags a long way behind the conybearian ideal, and retains its contempt for all those who, by presuming to teach, insinuate doubts as to its innate omniscience. lyell, however, clearly perceived that it was absolutely necessary that every teacher of professorial rank should be himself a pioneer in his subject--a fact of which government officials, as a rule, seem to be totally ignorant. his comments, a little later in the year, on the arrangements at the university of bonn are worth recording. "the professors have to lecture for nine months in the year--too much, i should think, for allowing time for due advancement of the teacher." lyell's desires in regard to remuneration seem reasonable enough. he is anxious to earn by his scientific work enough to provide for the extra expenses which this work entails, and yet to command sufficient time to advance his knowledge and reputation. the fates proved more propitious to him than they are generally to men of science, for he succeeded in accomplishing both of his desires. little of importance happened during the early part of . there was plenty of hard work in collecting facts, in consulting friends about special difficulties, and in working at the manuscript for the third volume of the "principles," for the second made its appearance almost with the new year. toil was sweetened by occasional pleasures, such as an evening with the somervilles, or a dinner party at the murchisons, a talk with babbage or fitton, or a symposium at the geological club, at which it is sometimes evident that good care was taken lest science should become too dry. one passage in his diary indicates that sixty years have considerably changed the habits of life in town and in the country, for at the present day most people would express themselves in the opposite sense. "i have enjoyed parties and two plays this month very much, because it was recreation stolen from work; but the difficulty in the country is that, on the contrary, one's hours of work are stolen from dissipation." the lectures at king's college were begun in may. lyell evidently was not a nervous man, but he regarded the near approach of this new kind of work with some trepidation, and admits that he slept ill before the first lecture. it was, however, a decided success in every respect, and the audience was a large one, for the council, after some hesitation, had permitted the attendance of ladies. each lecture was pronounced by the hearers to be better than the last, and lyell uses the opportunity, as he says, to fire occasional shots at buckland, sedgwick, and others who are still hankering after catastrophic convulsions and all-but universal deluges. as a further encouragement, his publisher, murray, agrees willingly to a reprint of the first volume of the "principles," and only hesitates between an edition of or of , copies. about this time, also, he was asked to undertake the presidency of the geological society, but that, notwithstanding murchison's urgency, he firmly declined for the present; writing of it to miss horner, "it is just one of those temptations the resisting of which decides whether a man shall really rise high or not in science. for two more years i am free from _les affaires administratives_, which, said old brochart in his late letter to me, have prevented _me_ from studying geology _d'une manière suivie_, whereby _you_ have already carried it so far." he was, however, soon to be engrossed in an "affair" of another kind; one which has proved very detrimental to the progress of many men of science, but which, in lyell's case, had the happiest results, and smoothed rather than it impeded his path to fame; for in the summer--on july th--he ceased to be a bachelor. the marriage was celebrated at bonn, where miss horner's family were still resident. a lutheran clergyman seems to have officiated, and the ceremony was a very quiet one; the distance from home preventing the attendance of english friends or even of relations of the bridegroom. the newly-married couple departed from bonn up the rhine, and travelled by successive stages to heidelberg, but they were not forgetful of geology, even in the first week of the honeymoon, for they visited as they journeyed more than one interesting section on the western edge of the odenwald. then they made excursions to carlsruhe and baden-baden, and ultimately travelled from freiburg to schaffhausen through the romantic defiles of the höllenthal, and across the corner of the black forest. a journal was now needless, and probably the newly-married couple were too much engrossed with their own happiness to write many letters, for few details have been preserved about their swiss tour. it was, however, comparatively a short one, for they remained less than a fortnight in the country. still lyell probably found it useful in refreshing recollections and testing his early impressions by greatly increased knowledge and experience. from the valley of the rhone they crossed the simplon pass into italy and followed the usual road to milan along the shore of the lago maggiore. how long they remained in italy, or by what route they returned to england, is not stated; indeed, for nearly six months next to nothing is on record concerning lyell's movements or work, but in the beginning of he and his wife were settled in london at no. , hart street, bloomsbury, which became their residence for some years. a state of happiness is not always indicated by much correspondence: probably it was so with lyell; at any rate, a single letter, dated january th, gives the only information of his doings between september, , and april, . in this letter, however, he mentions that the council of king's college had decided that in future ladies should not be admitted to lyell's lectures, and that, in consequence, he had received a pressing invitation from the managers of the royal institution to give, after easter, a course of six or eight lectures in their theatre, coupled with the offer of a substantial remuneration. at the end of april, as he tells his old friend mantell, both these courses had been begun. the one at the royal institution was attended by an audience of about , that at king's college, after the opening lecture, dropped down to a class of fifteen. the falling-off was entirely due to the above-named resolution. for this the council had assigned a reason, which, perhaps, was not a prudent course, for bodies of that kind, when they give reasons, often succeed only in "giving themselves away." the presence of ladies was forbidden, "because it diverted the attention of the young students, of whom," lyell remarks sarcastically, "i had _two_ in number from the college last year and _two_ this." had the council stated boldly that the college did not appoint professors to lecture _urbi et orbi_, their policy, though it would have appeared a little selfish and might have proved shortsighted, would have been defensible, because the institution was founded for the education of a particular class. but the reason assigned was open to lyell's retort, and gave the impression of unreality. it is not impossible that the decision was the result of secret "wire-pulling," and represented not so much a fear of the disturbing influence of the fair sex as a dread of the popularity of the subject. geology was still regarded with grave distrust by a very large number of people, and king's college, it must be remembered, was founded in the supposed interests of the church of england and in the hope of neutralising the effects of the unsectarian institution in gower street. many of its supporters may have been characterised rather by the ardour of their dislikes than by the width of their sympathies, and may have put pressure on the council, so that this body may have considered it safer to risk driving a popular man from their staff than to alienate an important section of their adherents and to expose the college to the danger of being charged with lending itself to heretical teaching.[ ] the preparation of these lectures must have been attended with some difficulty, for lyell writes that, "like all the world," he and his household--everyone except his wife--had been down with the influenza, which in that year was even more rampant in london than it has been in any of its recent visits. but, notwithstanding this and any other interruptions, the third and final volume of the "principles of geology" made its appearance in the month of may, . footnotes: [ ] life, letters, and journals, vol. i. p. . [ ] _ut suprà_, p. . [ ] further work has not verified some of these statements. there can be no question that a great deal of rock in the alps is much older than even the trias. the apparent superposition of crystalline schists to rocks with fossils is due to over-folding or over-thrust faulting--_i.e._ the schists are the older rocks. though the secondary rocks of the alps have undergone, in places, some modification and mineral changes, these are very different from the metamorphism of those crystalline schists which have a stratified origin. [ ] now "university college," london, having been incorporated by royal charter under that title in november, . [ ] _ut suprà_, p. . [ ] life, letters, and journals, vol. i. pp. - . [ ] when he left the publisher had not decided whether it should be issued at once or kept back till october. [ ] d'aubuisson, as time has shown, foresaw a real danger. the neglect of, if not contempt for, mineralogy, which became conspicuous between the years and , or thereabouts, seriously impeded the progress of geology, at any rate in england. [ ] life, letters, and journals, vol. i. p. . [ ] life, letters, and journals, vol. i. p. . [ ] life, letters, and journals, vol. i. p. . [ ] subsequent experience has shown that, while the above observations are beyond all question in the case of ordinary sedimentary rocks, structures curiously resembling lamination and ripple-mark may be produced in certain gneisses and crystalline schists by other causes. still, in many schists, they have originated in the way suggested by lyell, and indicate that the rock formerly was deposited by water. [ ] life, letters, and journals, vol. i. p. . [ ] _ut suprà_, p. . [ ] life, letters, and journals, vol. i. p. . [ ] the rev. w. d. conybeare, afterwards dean of llandaff, an eminent geologist, rather senior to lyell. [ ] life, letters, and journals, vol. i. p. . [ ] it was formerly conceded by the universities of oxford, cambridge, and dublin that a master of arts in any one could assume, under certain conditions, the same position in the others. this carried with it some privileges, though not the suffrage and the full rights of the degree. lyell had proceeded to the degree of m.a. at oxford in . [ ] life, letters, and journals, vol. i. p. . [ ] life, letters, and journals, vol. i. p. . [ ] _ut suprà_, p. . by the end of october it had not only ceased to grow, but also had been nearly washed away by the sea. now its position is marked by a shoal. [ ] life, letters, and journals, vol. i. p. . [ ] life, letters, and journals, vol. i. p. . [ ] life, letters, and journals, vol. i. p. . [ ] life, letters, and journals, vol. i. p. . [ ] lyell resigned the professorship after he had finished the course. chapter v. the history and place in science of the "principles of geology." the publication of the last volume of the "principles of geology" formed an important epoch in lyell's life. it brought to a successful close a work on which his energies had been definitely concentrated for nearly five years, and for which he had been preparing himself during a considerably longer time. it placed him, before his fourth decade was completed, at once and beyond all question in the front rank of british geologists; it carried his reputation to every country where that science was cultivated. it proved the writer to be not only a careful observer and a reasoner of exceptional inductive power, but also a man of general culture and a master of his mother tongue. the book, moreover, marked an epoch in geology not less important; it produced an influence on the science greater and more permanent than any work which had been previously written, or has since appeared--greater even than the famous "origin of species by natural selection," for that dealt only with one portion of geology--viz. with palæontology, while the method of the principles affected the science in every part. for a brief interval, then, we may desert the biography of the author for that of the book--the parent for his offspring--and call attention to one or two topics which are more immediately connected with the book itself. a brief sketch of its future history may be placed first; for, as its author was constantly labouring to improve and perfect his work, it underwent many changes in form and arrangement during the remainder--some two-and-forty years--of his life, which will be better understood from a connected statement than if they have to be gathered from scattered references in the other chapters of his biography. the first volume of the "principles of geology" appeared, as has been mentioned, in january, ; the second in january, ; and the third in may, . but a second edition of the first volume was issued in january, , and one of the second volume in the same month of ; these were all in vo size. a new edition of the whole work was published in may, . this, however, took the form of four volumes mo. this edition was called the third, because the first two volumes of the original work had gone through second editions. a fourth edition followed in june, , and a fifth in march, . thus far the "principles" continued without any substantial alteration, but the author made an important change in preparing the next edition. he detached from it the latter part--practically, the matter comprised in the third volume of the original work. this he rewrote and published separately as a single volume in july, , under the title of "elements of geology"; a sixth edition of the "principles," thus curtailed, appeared in three volumes mo, in june, . the effect of the change was to restrict the "principles" mainly to the physical side of geology--to the subjects connected with the morphological changes which the earth and its inhabitants alike undergo. thus it made the contents of the book accord more strictly with its title, while the "elements" indicated the working out of the aforesaid principles in the past history of the earth and its inhabitants--that is, the latter book deals with the classification of rocks and fossils, or with petrology and historical geology. the subsequent history of the "elements" may be left for the present. in february, , the seventh edition of the "principles" appeared, in which another change was made. this, however, was in form rather than in substance, for the book was now issued in a single thick vo volume. the eighth edition, published in may, ; and the ninth, in june, , followed the same pattern. a longer interval elapsed before the appearance of the tenth edition, and this was published in two volumes, the first being issued in november, , and the second in . in this interval--more than thirteen years--the science had made rapid progress, and the process of revision had been in consequence more than usually searching. the author, as he states in the preface, had "found it necessary entirely to rewrite some chapters, and recast others, and to modify or omit some passages given in former editions." many new instances were given to illustrate the effect which forces still at work had produced upon the earth's crust, and these strengthened the evidence which had been already advanced. into the accounts of vesuvius and etna much important matter was introduced, the result of visits which, as we shall find, lyell made in and ; the chapters relating to the vicissitudes of climate in past geological ages were entirely rewritten, together with that discussing the connection between climate and the geography of the earth's surface; and a chapter, practically new, was inserted, which considered "how far former vicissitudes in climate may have been influenced by astronomical changes; such as variations in the eccentricity of the earth's orbit, changes in the obliquity of the ecliptic, and different phases of the precession of the equinoxes." but the most important change was made in the later part of the book--the last fifteen chapters.[ ] these either were entirely new, or presented the original material in a new aspect. in the earlier editions of his work, lyell had expressed himself dissatisfied, as we have already seen, with the idea of the derivation of species from antecedent forms by some process of modification, and had pointed out the weak places in the arguments which were advanced in its favour. but the evidence adduced by darwin and wallace in regard to the origin of species by natural selection, strengthened by the support of hooker on the botanical side, had removed the difficulties which the cruder statements of lamarck and other predecessors had suggested to his mind, so that lyell now appears as a convinced evolutionist. the question also of the antiquity of man is much more fully discussed than it had been in the earlier editions. considerable changes were introduced into the eleventh edition, which appeared in january, , but these were chiefly additions which were made possible by the rapidly increasing store of knowledge, as, for instance, much important information concerning the deeper parts of the ocean. on this interesting subject great light had been thrown by the cruises of the several exploring vessels, notably those of the _lightning_, the _bulldog_, and the _porcupine_, commissioned by the british government--cruises in the course of which soundings had been taken and temperatures observed in the north atlantic down to depths of about , fathoms; and in the lowest parts of the western basin of the mediterranean. samples also of the bottom had been obtained, and, in many cases, even dredgers had been successfully employed at these depths. thanks to the skill of the mechanician, the way had been opened which led into a new fairyland of science. this was not, like some fabled paradise, guarded by mountain fastnesses and precipitous ramparts of eternal snow; it was not encircled by storm-swept deserts, or secluded in the furthest recesses of forests, hitherto impenetrable; but it lay deep in the silent abysses of ocean--on those vast plains, which are unruffled by the most furious gale, or by the wildest waves. in these depths, beneath the tremendous pressure of so vast a thickness of water, and far below the limits at which the existence of life had been supposed to be possible, numbers of creatures had been discovered--many of them strange and novel: molluscs, sea-lilies, glassy sponges of unusual beauty--creatures often of ancient aspect, relics of a fauna elsewhere extinct; and the ocean floor, on and above which they moved, was strewn with the white dust of countless coverings of tiny foraminifera, which, even if none were actually living, had fallen like a gentle but incessant rain from the overhanging mass of water. similar changes were introduced into the twelfth edition of the "principles," upon which the author was engaged even up to the last few weeks of his life. the _challenger_, it will be remembered, started on her memorable voyage of exploration at the close of the year in which the eleventh edition had appeared; and though she did not actually return till after lyell's death, notes of some of her most interesting discoveries had been communicated from time to time to the scientific journals of this country. the edition, however, was left incomplete. the first volume had been passed for the press, but the second was still unfinished; so that this twelfth edition was posthumous, the work of revision having been finished by the author's nephew and heir, mr. leonard lyell. by such conscientious and unremitting labour, the scientific value of the "principles" was immensely increased; it kept always in step with the advance of the science, but at the same time it lost, as was inevitable, a little of that literary charm and that sense of freshness which was at first so marked a characteristic. books, like children, are apt to lose some of their beauty as they increase in size and strength. one must compare an early and a late edition, such as the first or third and the tenth or eleventh, in order to realise how great were the changes in this passage from childhood to adolescence. new material was incorporated into every part; it makes its appearance sometimes on every page; changes are made in the order of the subjects; many chapters are entirely rewritten; nevertheless, a considerable portion corresponds almost word for word in the two editions. lyell was no hurried writer, or "scamper" of work; he paid great attention to composition, so that when the facts which he desired to cite had undergone no change, he very seldom found any to make in his language. nevertheless, here and there, some small modification, a slight verbal difference, a trifling alteration in the order of a sentence, the insertion of a short clause to secure greater perspicuity, shows to how careful and close a revision the whole had been subjected. in the substance of the work, besides the excision of nearly one-third of the material and the complete reconstruction of the part relating to the antiquity of man and the origin of species, already mentioned, the following are the most important changes. the chapters which discuss the evidence in favour of past mutations of climate and the causes to which these are due, are rewritten and greatly enlarged. in the earlier editions, the effects of geographical changes were regarded as sufficient to account for all the climatal variations that geology requires; in the later editions, the possible co-operation of astronomical changes is admitted. great additions also are made to the parts referring to the condition of the bed of the ocean, and much new and important information is incorporated into the sections dealing with volcanoes and earthquakes; including many valuable observations which had been made during visits to vesuvius and to etna in the autumns of and . the section on the action of ice is so altered and enlarged as to be practically new; for when the first edition of the "principles" was published comparatively little was known of the effects of land-ice, and the art of following the trail of vanished glaciers had yet to be learnt. but, with this exception, the part of the book dealing with the action of the forces of nature--heat and cold, rain, rivers, and sea--remains comparatively unaltered, as do the first five chapters, which give a sketch of the early history of the science of geology. without some knowledge of this history it is hardly possible to appreciate the true greatness of the "principles," and its unique value as an influence on scientific thought at the time it appeared. this, however, to some extent may be inferred from those chapters which we have mentioned; but the perspective of half a century enables us to understand it better at the present time; for the author, of course, had to deal with contemporary work and opinion only in a very indirect way. we may dismiss briefly the crude speculations of the earliest observers--those anterior to the christian era--of which the author gives a summary in the second chapter of the "principles"; for at that early date few persons had made any effort to arrange the facts of nature in a connected system. these were too scanty and too disconnected for any such effort to be successful. the general result cannot be better summed up than in lyell's own words:-- "although no particular investigations had been made for the express purpose of interpreting the monuments of ancient changes, they were too obvious to be entirely disregarded; and the observation of the present course of nature presented too many proofs of alterations continually in progress on the earth to allow philosophers to believe that nature was in a state of rest, or that the surface had remained and would continue to remain, unaltered. but they had never compared attentively the results of the destroying and the reproductive operations of modern times with those of remote eras; nor had they ever entertained so much as a conjecture concerning the comparative antiquity of the human race, or of living species of animals and plants, with those belonging to former conditions of the organic world. they had studied the movements and positions of the heavenly bodies with laborious industry, and made some progress in investigating the animal, vegetable, and mineral kingdoms; but the ancient history of the globe was to them a sealed book, and though written in characters of the most striking and imposing kind, they were unconscious even of its existence."[ ] the above remarks hold good for the centuries immediately succeeding the christian era; and the influence of the new faith, when it ceased to be persecuted and became a power in the state, was adverse on the whole to progress in physical or natural science. with the decline of the roman empire a great darkness fell upon the civilised world; art, science, literature withered before the hot breath of war and rapine, as the northern barbarians swept down upon their enfeebled master on their errand of destruction. it was well nigh eight centuries from the christian era before the spirit of scientific enquiry and the love of literature began to awaken from their long torpor; and it was then among people of an eastern race and an alien creed. the caliphs of bagdad encouraged learning, and the students of the east became familiar by means of translations with the thoughts and questionings of ancient greece and rome. the efforts of their earliest investigators have not been preserved, but in treatises of the tenth century--written by one avicenna, a court physician, the "formation and classification of minerals" is discussed, as well as the "cause of mountains." in the latter attention is called to the effect of earthquakes, and to the excavatory action of streams. in the same century also, "omar the learned" wrote a book on "the retreat of the sea," in which he proved by reference to ancient charts and by other less direct arguments that changes of importance had occurred in the form of the coast of asia. but even among the followers of mohammed theology declared itself hostile to science; the moslem doctors of divinity deemed the pages of the koran, not the book of nature, man's proper sphere of research, and considered these difficulties ought to be settled by a quotation from the one rather than by facts from the other. so progress in science was impeded, and recantations at the bidding of ecclesiastics are not restricted to the annals of christian races. but men seem to have gone on speculating, and mohammed kazwini, in a striking allegory which is quoted by lyell, tells his readers how (to use the words of tennyson)[ ]:-- "there rolls the deep where grew the tree. o earth, what changes thou hast seen! there, where the long street roars, hath been the stillness of the central sea." in europe geological phenomena do not appear to have attracted serious attention till the sixteenth century, when the significance of fossils became the subject of an animated controversy in italy. at that epoch this country held the front rank in learning and the arts, and an inquiry of that nature arose almost as a matter of course, because the marls, sands, and soft limestones of its lower districts teem in many places with shells and other marine organisms in a singular state of perfection and preservation. it is interesting to remark, that among the foremost in appealing to inductive processes for the explanation of these enigmas was that extraordinary and almost universal genius, leonardo da vinci. he ridiculed the current idea that these shells were formed "by the influence of the stars," calling attention to the mud by which they were filled, and the gravel beds among which they were intercalated, as proof that they had once lain upon the bed of the sea at no great distance from the coast. his induction rested on the evidence of sections which had been exposed during his construction of certain navigable canals in the north of italy. shortly afterward, the conclusions of leonardo were amplified, and strengthened on similar grounds by frascatoro. he, however, not only demonstrated the absurdity of explaining these organic structures by the "plastic force of nature"--a favourite refuge for the intellectually destitute of that and even a later age, but he also showed that they could not even be relics of the noachian deluge. "that inundation, he observed, was too transient; it had consisted principally of fluviatile waters; and if it had transported shells to great distances, must have strewed them over the surface, not buried them at vast depths in the interior of mountains." as lyell truly remarks, "his clear exposition of the evidence would have terminated the discussion for ever, if the passions of man had not been enlisted in the dispute; and even though doubts should for a time have remained in some minds, they would speedily have been removed by the fresh information obtained almost immediately afterwards, respecting the structure of fossil remains, and of their living analogues." but the difficulties raised by theologians, and the general preference for deductive over inductive reasoning, greatly impeded progress. it was not till the methods of the schoolmen yielded place to those of the natural philosophers that the tide of battle began to turn, and science to possess the domains from which she had been unjustly excluded. for about a century the weary war went on; the philosophers of italy leading the van, those of england, it must be admitted, for long lagging behind them, before the spectre of "plastic force" was finally dismissed to the limbo of exploded hypotheses in england. for instance, it was seriously maintained by the well-known writer on county history, dr. plot, in the last quarter of the seventeenth century, though its absurdity had been demonstrated by his italian contemporaries; as by scilla, in his treatise on the fossils of calabria, and by steno, in that on "gems, crystals, and organic petrifactions enclosed in solid rocks." the latter had proved by dissecting a shark recently captured in the mediterranean, that its teeth and bones corresponded exactly with similar objects from a fossil in tuscany, and that the shells discovered in sundry italian strata were identical with living species, except for the loss of their animal gluten and some slight mineral change. moreover, he had distinguished, by means of their organic remains, between deposits of a marine and of a fluviatile character. but now, as the "plastic force" dogma lost its hold on the minds of men, its place was taken by that which regarded all fossils as the relics of an universal deluge. "the theologians who now entered the field in italy, germany, france, and england, were innumerable; and henceforward, they who refused to subscribe to the position that all marine organic remains were proofs of the mosaic deluge, were exposed to the imputation of disbelieving the whole of the sacred writings. scarce any step had been made in approximating to sound theories since the time of frascatoro, more than a hundred years having been lost in writing down the dogma that organised fossils were mere sports of nature. an additional period of a century and a half was now destined to be consumed in exploding the hypothesis that organised fossils had all been buried in the solid strata by noah's flood."[ ] into the varying fortunes of this second struggle it is needless to enter at any length. it was the old conflict between theology and science in a yet more acute form; the old warfare between deductive and inductive reasoning; between dogmatic ignorance and an honest search for truth. protestants and romanists alike seemed to claim the gift of infallibility, with the right to decide _ex cathedrâ_ on questions of which they were profoundly ignorant, and to pronounce sentence in causes where they could not even appreciate the evidence. ecclesiastics scolded; well-meaning though incompetent laymen echoed their cry; the more timorous among scientific men wasted their time in devising elaborate but futile schemes of accommodation between the discoveries of geology and the supposed revelations of the scriptures; the stronger laboured on patiently, gathering evidence, strengthening their arguments and dissecting the fallacies by which they were assailed, until the popular prejudice should be allayed and men be calm enough to listen to the voice of truth. it was a long and weary struggle, which is now nearly, though not quite, ended; for there are still a few who mistake for an impregnable rock that which is merely the shifting-sand of popular opinion, and cannot realise that the province of revelation is in the spiritual rather than in the material, in the moral rather than in the scientific order. the outbursts of denunciation aroused by the assertion of the antiquity of man and the publication of the "origin of species," which many still in the full vigour of their powers can well remember, were but a recrudescence of the same spirit, a reappearance of an old foe with a new face. but when lyell was young and the idea of the "principles" began to germinate in his mind, popular prejudice against the free exercise of inquiry in geology was still strong; this diluvial hypothesis still hampered, if it did not fully satisfy, the majority of scientific workers. here and there, it is true, some isolated pioneer demonstrated the impossibility of referring the fossil contents of the earth's crust to a single deluge, or protested against the singular mixture of actual observation, patristic quotation, and deductive reasoning which commonly passed current for geological science. chief and earliest among these men, vallisneri, also an italian, about a century before lyell's birth, was clearsighted enough to see "how much the interests of religion as well as those of sound philosophy had suffered by perpetually mixing up the sacred writings with questions in physical science"; indeed, he was so far advanced as to attempt a general sketch of the marine deposits of italy, with their organic remains, and to arrive at the conclusion that the ocean formerly had extended over the whole earth and after remaining there for a long time had gradually subsided. this conclusion, though inadequate as an expression of the truth, was much more philosophical than that of an universal and comparatively recent deluge. moro and generelli, in the same country, followed the lead of vallisneri, in seeking for hypotheses which were consistent with the facts of nature, generelli even arriving at conclusions which, in effect, were those adopted by lyell, and have been thus translated by him: "is it possible that this waste should have continued for six thousand and perhaps a greater number of years, and that the mountains should remain so great unless their ruins have been repaired? is it credible that the author of nature should have founded the world upon such laws as that the dry land should be for ever growing smaller, and at last become wholly submerged beneath the waters? is it credible that, amid so many created things, the mountains alone should daily diminish in number and bulk, without there being any repair of their losses? this would be contrary to that order of providence which is seen to reign in all other things in the universe. wherefore i deem it just to conclude that the same cause which, in the beginning of time, raised mountains from the abyss, has down to the present day continued to produce others, in order to restore from time to time, the losses of all such as sink down in different places, or are rent asunder, or in other ways suffer disintegration. if this be admitted, we can easily understand why there should now be found upon many mountains so great a number of crustacea and other marine animals." this attempt at a system of rational geology was a great advance in the right direction, though many gaps still remained to be filled up and some errors to be corrected; such for instance as the idea adopted by generelli from moro, and maintained in other parts of his work, that all the stratified rocks are derived from volcanic ejections. nevertheless, geology, by the middle of the eighteenth century, had evidently begun to pass gradually, though very slowly, from the stage of crude and fanciful hypotheses to that of an inductive science. but even then the observers had only succeeded in setting foot on the lower slopes of a peak, the summit of which will not be reached, if indeed it ever be, for many a long year to come. during the next half of the century progress was made, now in this direction, now in that; slowly truths were established, slowly errors dispelled; and as the close of that century approached, the foundations of modern geology began to be securely laid. a great impulse was given to the work, though to some extent the apparent help proved to be a real hindrance, by that famous teacher, werner of freiberg, in saxony. his influence was highly beneficial, because he insisted not only on a careful study of the mineral character of rocks, but also on attending to their grouping, geographical distribution, and general relations. it was hurtful almost to as great a degree, because he maintained, and succeeded by his enthusiasm and eloquence in impressing on his disciples, most erroneous notions as to the origin of basalts and those other igneous rocks which were formerly comprehended under the name "trap." such rocks he stoutly asserted to be chemical precipitates from water, and, besides this, he held views in general strongly opposed to anything like the action of uniform causes in the earth's history. in short, the saxon professor was in many respects the exact antithesis of lyell, and the points of essential contrast cannot be better indicated than in the words of the latter.[ ] "if it be true that delivery be the first, second, and third requisite in a popular orator, it is no less certain that to travel is of first, second, and third importance to those who desire to originate just and comprehensive views concerning the structure of our globe. now werner had not travelled to distant countries; he had merely explored a small portion of germany, and conceived, and persuaded others to believe, that the whole surface of our planet and all the mountain-chains in the world were made after the model of his own province. it became a ruling object of ambition in the minds of his pupils to confirm the generalisations of their great master, and to discover in the most distant parts of the globe his 'universal formations,' which he supposed had been each in succession simultaneously precipitated over the whole earth from a common menstruum or chaotic fluid." these wild generalisations, as lyell points out, had not even the merit of being really in accordance with the evidence afforded by some parts of saxony itself. werner, in fact, was a conspicuous example of a tendency, which perhaps even now is not quite extinct, to work too much beneath a roof and too little in the open air; to found great generalisations on the minute results of research in a laboratory, without subjecting them to actual tests by the study of rocks in the field. this error on werner's part was the less excusable, because, even before he began to lecture, the true nature of basalts and traps generally had been recognised by several observers of different nationalities. in the hebrides and in iceland, in the vicentin and in auvergne, even in hesse and in the rheingau, proof after proof had been cited, and the evidence in favour of the "igneous" origin of these rocks had become irresistible, as one might suppose, within some half dozen years of werner's appointment as professor at freiberg. faujas, in , published a description of the volcanoes of the vivarais and velay, in which he showed how the streams of basalt had poured out from craters which still remain in a perfect state. desmarest also pointed out that in auvergne "first came the most recent volcanoes, which had their craters still entire and their streams of lava conforming to the level of the present river courses. he then showed that there were others of an intermediate epoch, whose craters were nearly effaced, and whose lavas were less intimately connected with the present valleys; and lastly, that there were volcanic rocks still more ancient without any discernible craters or scoriæ, and bearing the closest analogy to rocks in other parts of europe, the igneous origin of which was denied by the school of freiberg." desmarest even constructed and published a geological map of auvergne, of which lyell speaks in terms of high commendation. "they alone who have carefully studied auvergne, and traced the different lava streams from their craters to their termination--the various isolated basaltic cappings--the relation of some lavas to the present valleys--the absence of such relations in others--can appreciate the extraordinary fidelity of this elaborate work."[ ] but before the close of the eighteenth century, two champions had already stepped into the arena to withstand the wernerian hypothesis, which, like a swelling tide, was spreading over europe, and threatening to sweep away everything before it. these were james hutton and william smith; the one born north, the other south of the tweed. from the name of the former that of his friend and expositor, john playfair, must never be separated. they were the socrates and the plato of that school of thought from which modern geology has been developed.[ ] to quote the eloquent words of sir archibald geikie[ ]:-- "on looking back to the beginning of this century we see the geologists of britain divided into two hostile camps, which waged against each other a keen and even an embittered warfare. on the one hand were the followers of hutton of edinburgh, called from him the vulcanists, or plutonists; on the other, the disciples of werner ... who went by the name of wernerians, or neptunists.... the huttonians, who adhered to the principles laid down by their great founder, maintained, as their fundamental doctrine, that the past history of our planet is to be explained by what we can learn of the economy of nature at the present time. unlike the cosmogonists, they did not trouble themselves with what was the first condition of the earth, nor try to trace every subsequent phase of its history. they held that the geological record does not go back to the beginning, and that therefore any attempt to trace that beginning from geological evidence was vain. most strongly, too, did they protest against the introduction of causes which could not be shown to be a part of the present economy. they never wearied of insisting that to the everyday workings of air, earth, and sea, must be our appeal for an explanation of the older revolutions of the globe. the fall of rain, the flow of rivers, the slowly crumbling decay of mountain, valley, and shore, were one by one summoned as witnesses to bear testimony to the manner in which the most stupendous geological changes are slowly and silently brought about. the waste of the land, which they traced everywhere, was found to give birth to soil--renovation of the surface thus springing phoenix-like out of its decay. in the descent of water from the clouds to the mountains, and from the mountains to the sea, they recognised the power by which valleys are carved out of the land, and by which also the materials worn from the land are carried out to the sea, there to be gathered into solid stone--the framework of new continents. in the rocks of the hills and valleys they recognised abundantly the traces of old sea-bottoms. they stoutly maintained that these old sea-bottoms had been raised up into dry land from time to time by the powerful action of the same internal heat to which volcanoes owe their birth, and they pointed to the way in which granite and other crystalline rocks occur as convincing evidence of the extent to which the solid earth has been altered and upheaved by the action of these subterranean fires." such were the leading principles of the "huttonian theory," though perhaps they are stated here in a slightly more developed form than when it was first presented by its illustrious author. but it was defective in one important respect, on a side from which it might have obtained the strongest support, and have liberated itself from the bondage of deluges; in other words, of convulsive action, by which it was still fettered, for "it took no account of the fossil remains of plants and animals. hence it ignored the long succession of life upon the earth which those remains have since made known, as well as the evidence thereby obtainable as to the nature and order of physical changes, such as alternations of sea and land, revolutions of climate, and suchlike." this defect was supplied by william smith. he had learnt, by patient labour among the stratified rocks of england, to recognise their fossils, had ascertained that certain assemblages of the latter characterised each group of strata, and by this means had traced such groups through the country, and had placed them in order of superposition. so early as , he published a "tabular view of the british strata," and from that time was engaged at every spare moment in constructing a geological map of england, all the while freely communicating the results of his researches to his brethren of the hammer. "the execution of his map was completed in , and it remains a lasting monument of original talent and extraordinary perseverance; for he had explored the whole country on foot without the guidance of previous observers, or the aid of fellow labourers, and had succeeded in throwing into natural divisions the whole complicated series of british rocks."[ ] a most important step in view of future progress, at any rate in our own country, was taken by the foundation of the geological society of london in , the members of which devoted themselves at first rather to the collection of facts than to the construction of theories, while in france the labours of brongniart and cuvier in comparative osteology, and of lamarck in recent and fossil shells, smoothed the way toward the downfall of catastrophic geology. those men, with their disciples, "raised these departments of study to a rank of which they had never before been deemed susceptible. their investigations had eventually a powerful effect in dispelling the illusion which had long prevailed concerning the absence of analogy between the ancient and modern state of our planet. a close comparison of the recent and fossil species, and the inferences drawn in regard to their habits, accustomed the geologist to contemplate the earth as having been at successive periods the dwelling-place of animals and plants of different races--some terrestrial, and others aquatic; some fitted to live in seas, others in the waters of lakes and rivers. by the consideration of these topics the mind was slowly and insensibly withdrawn from imaginary pictures of catastrophes and chaotic confusion, such as haunted the imagination of the early cosmogonists. numerous proofs were discovered of the tranquil deposition of sedimentary matter, and the slow development of organic life."[ ] such was the earlier history of geology; such were the influences which had moulded its ideas till within a few years of the date when lyell began to make it a subject of serious study. at that time, namely about the year , the geological society of london had become the centre and meeting-point of a band of earnest and enthusiastic workers, whose names will always hold an honoured place in the annals of the science. among the older members--most of whom, however, were still in the prime of life, were such men as buckland, conybeare, fitton, greenough, horner, macculloch, warburton and wollaston; among the younger, de la beche and scrope, sedgwick and whewell. murchison, though a few years lyell's senior, was by almost as many his junior as a geologist, for he did not join the society till the end of , and was actually admitted on the evening when lyell, then one of its honorary secretaries, read his first paper--on the marl-lake at kinnordy. such men also as babbage, herschel, warburton, sir philip egerton, the earl of enniskillen (then viscount cole), must not be forgotten, who were either less frequent visitors or more directly devoted to other studies. at this time geology was passing into a phase which endured for some forty years--the exaltation of the palæontological, the depreciation of the mineralogical side. if it be true, as it has been more than once remarked, that the father of the geologist was a mineralogist, it is no less true that his mother was a palæontologist; but at this particular epoch the paternal influence obviously declined, while that of the mother became inordinately strong. wollaston and macculloch, indeed, were geologists of the old school; excellent mineralogists and petrologists (to use the more modern term) as accurate as it was possible to be with the appliances at their disposal, but among the younger men de la beche, accompanied to a certain extent by scrope and sedgwick, was almost alone in following their lead. but although palæontology and stratigraphical geology as its associate were clearly making progress, the school of thought, of which lyell became the champion, counted at this time but few adherents, for the older geologists were almost to a man "catastrophists." a few, like macculloch, undervalued palæontological research, and thus were doubly prejudiced against the uniformitarian views. buckland, conybeare, greenough, as we have already seen from incidental remarks in lyell's letters, had put their trust in deluges, and imagined that by such an agency the earth had been prepared for a new creation of living things and a new group of geological formations. sedgwick even was to a great extent on their side. he had speedily emerged from the waters of wernerism, in which at first he had been for a short time immersed, but he did not escape so easily from the roaring floods of diluvialists, and the grandeur of catastrophic changes in the crust of the earth fascinated his enthusiastic, almost poetic, nature. even so late as , we find him criticising from the chair of the geological society the leading argument of lyell's "principles of geology" in no friendly spirit, and bestowing high praise on elie de beaumont's theory of parallel mountain-chains. a brief summary of the views advocated by this eminent french geologist may serve to indicate, perhaps better than any general statements, the influences against which lyell had to contend at the outset of his career as a geologist. with the omission of certain parts, to which no exception would be taken, or which have no very direct bearing upon the immediate question, they are as follows[ ]: ( ) in the history of the earth there have been long periods of comparative repose, during which the sedimentary strata have been continuously deposited, and short periods of paroxysmal violence, during which that continuity has been interrupted. ( ) at each of these periods of violence or revolution in the state of the earth's surface, a great number of mountain-chains have been formed suddenly, and these chains, if contemporaneous, are parallel; but if not so, generally differ in direction. ( ) each revolution or great convulsion has coincided with the date of another geological phenomenon, namely, the passage from one independent sedimentary formation to another, characterised by a considerable difference in "organic types." ( ) there has been a recurrence of these paroxysmal movements from the remotest geological periods; and they may still be produced. thus the force of authority, which has to be reckoned with in geology, if not in other branches of science, was in the main adverse to lyell, who could count on but few to join him in his attack on catastrophism. one indeed there was, a host in himself, who, though his contemporary in years, had devoted himself wholly to geology at a slightly earlier date and had already become convinced, by his field-work in italy and france, of the efficacy of existing forces to work mighty changes, if time were given, in the configuration of the earth's surface. this was george poulett scrope, a man of broad culture, great talents, and singular independence of thought, who had convinced himself of the errors of the wernerian theory by his studies in italy in the years - , and had thoroughly explored the volcanic district of auvergne in . his work on the phenomena of volcanoes, published in , and that on the geology of central france, published in , had given the _coup de grace_ to werner's hypothesis and had made the first breach in the fortress of the catastrophists. for a complete solution of the problem to which lyell had addressed himself, two methods of investigation were necessary. it must be demonstrated that in tracing back the life history of the earth from the present age to a comparatively remote past no breach of continuity could be detected, and that the forces which were still engaged in sculpturing and modifying this earth's surface were adequate, given time enough, to produce all those changes to which the catastrophist appealed as proofs of his hypotheses. to establish the one conclusion, it was necessary to make a careful study of the tertiary formations, which were still in a condition of comparative confusion; to arrange them in an order no less clear and definite than that of the secondary systems; and to show, by working downward from the present fauna, not only that many living species had been long in existence, but also that these had appeared gradually, not simultaneously, and had in like manner replaced forms which had one after another vanished--to prove, in short, "that past and present are bound together by an unsevered cord of life, whose interlacing strands carry us back in orderly change from age to age." to establish the other conclusion it was necessary to show that, even in historical times, considerable changes had occurred in the outlines of coasts, and that heat and cold, the sea, or rain and rivers--especially the last--had been agents of the utmost importance in the sculpture of cliffs, valleys, and hills. for both these purposes careful study, not only in britain, but also still more in other regions, was absolutely necessary, and it was with them in view that lyell undertook his journeys, from the time when his geological ideas began to assume a definite shape until the last volume of the "principles" was published. by that date, as has been stated in the preceding chapters, he had made himself familiar in the course of his geological education with many parts of britain, had laboriously investigated the more important collections and museums of france and italy, and had carefully studied in the field the principal tertiary deposits not only in these countries but also in sicily and in parts of switzerland and germany. to obtain evidence bearing on the physical aspect of the question on a scale grander than was afforded by the undulating lowlands, or worn-down highland regions of britain and the neighbouring parts of europe, he had rambled among the alps and pyrenees, examining their peaks and precipices, their snowfields, glaciers, lakes, and torrents, and watching the processes of destruction, transportation, and deposition of which crag, stream, and plain afford a never-ending object-lesson. in order to study volcanoes still in activity, he had climbed vesuvius and etna; in order to scrutinise more minutely the structure of cones, craters, and lava streams, he had visited auvergne, catalonia, and the eifel; while in all his goings and comings through scenes where nature worked more unobtrusively, he had watched her never-ending toil, as she destroyed with the one hand and built with the other. he was thus able to write with the authority of one who has seen, not of one who merely quotes; of one who knew, not of one who had learnt by rote. the "principles of geology," though of course it had to rely not seldom on the work of others, bore the stamp of the author's experience, and was redolent, not of the dust of libraries, but of the sweetness of the open air. that fact added no little force to its cautious and clear inductive reasoning; that fact did much to disarm opposition, and to open the way to victory. footnotes: [ ] strictly speaking, fifteen out of the last sixteen chapters, for the final one (dealing with coral reefs) is substantially a reprint. [ ] "principles of geology," vol. i. p. (eleventh edition). [ ] _in memoriam_, cxxiii. [ ] "principles of geology," chap. iii. p. . [ ] "principles of geology," chap. iv. [ ] "principles of geology," chap. iv. [ ] hutton's "theory of the earth" was first published in , and in an enlarged form in . playfair's "illustrations of the huttonian theory" appeared in the spring of . [ ] geikie's "life of murchison," chap. vii. [ ] "principles of geology," chap. iv. [ ] "principles of geology," chap. iv. [ ] abridged from lyell's summary: "principles of geology," chap. vii. chapter vi. eight years of quiet progress. both courses of lectures ended[ ] and the third volume of the "principles" successfully launched, mr. and mrs. lyell left london in june, , for another continental tour. during their first halt, at paris, she was duly introduced to the famous quarries of montmartre, and had an opportunity of "collecting a fossil shell or two for the first time." thence they made their way to bonn, which she had left as a bride the previous summer, and, after another short halt, proceeded up the gorge of the rhine to bingen, visiting on the way the ironworks at sayn, and examining the stratified volcanic deposits on the plain between the river and that town. the tertiary basin at mayence was next visited, and from it they went leisurely to heidelberg. from the picturesque old town by the neckar they struck off to stuttgart and to pappenheim, examining one or two collections at the former place, and the quarries of solenhofen, near the latter. these were already noted for the abundant and well-preserved fossils obtained in the quarries worked for the well-known "lithographic stone," though the famous archæopteryx had yet to be found; that strange creature, feathered and like a bird, but with teeth in its beak and a tail like a reptile, which has supplied such an important link in the chain of evidence in favour of progressive development. thence they travelled to nürnberg and bayreuth, visiting on their way the noted caves at muggendorf, and returned to bonn by way of bamberg, würtzburg, aschaffenberg, and frankfurt. in this journey, few localities of special interest were investigated, but, as lyell's letters show, no opportunity was lost of discussing important questions with local geologists, or of examining sections in the field. but on the way back to england through belgium a halt was made at liége, to inspect dr. schmerling's grand collection of cave-remains. it is evident, though but a short notice of it has been preserved, that this visit kindled an enthusiasm which was to produce important results in later years. lyell writes (to mantell, after his return to england):-- "i saw at liége the collection of dr. schmerling, who in three years has, by his own exertion and the incessant labours of a clever amateur servant, cleared out some twenty caves untouched by any previous searcher, and has filled a truly splendid museum. he numbers already thrice the number of fossil cavern mammalia known when buckland wrote his 'idola specus'; and such is the prodigious number of the individuals of some species--the bears, for example, of which he has five species, one large, one new--that several entire skeletons will be constructed. oh, that the lewes chalk had been cavernous! and he has these, and a number of yet unexplored and shortly to be investigated holes, all to himself: but envy him not--you cannot imagine what he feels at being far from a metropolis which can afford him sympathy; and having not one congenial soul at liége, and none who take any interest in his discoveries save the priests--and what kind _they_ take you may guess, more especially as he has found human remains in breccia, embedded with the extinct species, under circumstances far more difficult to get over than any i have previously heard of. the _three_ coats or layers of stalagmite cited by me at choquier are quite true."[ ] very probably among these human relics was one which was destined to become famous--the skull found in the cave at engis--for this was described by dr. schmerling in his "recherches sur les ossements fossiles découverts dans les cavernes de la province de liége," a book published in . it was found at a depth of nearly five feet, hidden under an osseous breccia, composed of the remains of small animals, and containing one rhinoceros tusk with several teeth of horses and of ruminants. the earth in which it was lying did not show the slightest trace of disturbance, and teeth of rhinoceros, horse, hyæna, and bear surrounded it on all sides.[ ] this relic proved--and since then numbers of similar cases have been discovered--that if the man of engis were an antediluvian, and his corpse had been washed into the cave together with the drowned bodies of rhinoceros, and other animals,[ ] that event, at any rate, must have corresponded with a great change in the habits of the larger mammalia, for they had been unable to return to haunts which once had been congenial. in other words, the foundation was being laid, now in , for the next great advance in geological science, the contemporaneity of man and several extinct species of mammals, indicating, of course, the antiquity of the human race. to this point, however, public attention was not directed for nearly twenty years. then various causes, especially an examination into the evidence discovered in the neighbourhood of abbeville and amiens by m. boucher de perthes, brought the question to the front. but though the controversy was sharp and bitter for a time, it was speedily over, and the question which is still agitated--though mildly and in a sense wholly scientific--is whether man appeared in this part of europe and in corresponding regions of north america, before, during, or after the glacial epoch? but the engis skull is a relic exceptionally interesting. though the handiwork of primæval man is common enough--rudely chipped instruments or weapons of flint or other stone, worked portions of bones and antlers, and such like--yet his bones are far less common than those of other mammals, and, most of all, skulls are rare. professor huxley, in his work from which we have already quoted, states that dr. schmerling found a bone implement in the engis cave, and worked flints in all the ossiferous belgian caves, yet this was the only skull in anything like a perfect condition, though another cavern furnished two fragments of parietal bones. yet from the latter numerous bones of the extremities were obtained, and these had belonged to three individuals. what inferences, then, can be drawn from this skull as to the intellectual rank of primæval man? this question was discussed by its discoverer, and the evidence has been also considered by professor huxley. the former thus expressed his opinion, "that this cranium has belonged to a person of limited intellectual faculties, and we conclude thence that it belonged to a man of a low degree of civilisation; a deduction which is borne out by contrasting the capacity of the frontal with that of the occipital region." professor huxley sums up a careful discussion of the evidence, in which he calls special attention to points where it happens to be defective, by stating that the specimen agrees in certain respects with australian skulls, in others with some european, but that he can find in the remains no character which, if it were a recent skull, would give any trustworthy clue to the race to which it might appertain. "assuredly there is no mark of degradation about any part of its structure. it is, in fact, a fair average human skull, which might have belonged to a philosopher, or might have contained the thoughtless brains of a savage."[ ] the winter of and the spring of the following year were spent in london. it was evidently a busy, though uneventful, time: a new edition of the "principles" was being prepared and printed, a paper read to the geological society on a freshwater formation at cerdagne in the pyrenees, and information collected for a summer's journey. this was to be in a new direction--to scandinavia--with the more especial intent of studying the evidence on which it has been asserted that the shores of the baltic had changed their level within recent times. but on this occasion mrs. lyell remained at home, as the travelling might occasionally have been too rough for her so we find, in a journal written for her perusal, a full sketch of a tour which proved, as he had anticipated, to be fruitful in scientific results. his first halt was at hamburg, where, on his arrival, with characteristic energy he dashed off at once in a carriage to examine a section below altona which he had marked down on his voyage up the elbe. this is his brief summary: "cliffs sixty or seventy feet high. filled three pages of note-book. saw the source of the great holstein granite blocks. gathered shells thrown ashore by the elbe." from hamburg he drove to lübeck, along one of the worst of roads. the primary cause of its badness was geological--a loose sand interspersed with granite boulders; the secondary, the royal revenues; for these largely depended on the tolls paid by vessels on entering the sound, and if a good road had connected the two towns much merchandise would have gone overland, to the king's loss. at lübeck lyell for the first time stood upon the shore of the baltic, and utilised the half-hour before his steamer started for copenhagen by hunting for shells. as a reward, he found a well-known freshwater genus (_paludina_) among common marine forms.[ ] from copenhagen a rapid journey in seeland and to möen introduced him to a number of interesting sections of the drift, accounts of which were afterwards worked into his books, and showed him at faxoe and elsewhere limestones overlying the upper chalk, like those at maestricht in holland, and at meudon near paris. all these limestones possess an exceptional interest, for they contain a mixture of secondary with tertiary fossils, and thus help to fill up the wide gap between these two great divisions in britain and the adjacent parts of europe. on his return to copenhagen lyell was very kindly received by the crown prince, who was an ardent naturalist, and allowed him to examine a fine collection of minerals and fossils accumulated by himself. after crossing the sound to malmö, lyell spent about a fortnight in driving along an inland route through the southern part of sweden to norrköping, while a halt at lund afforded the opportunity of pleasant talks with the professors of the university, and of seeing some formations of which hitherto he had not had much experience. the terms in which he refers to these indirectly proves what strides geology has taken in the last sixty years. "we made an excursion together through a country of greywacke with orthoceratite limestone and schist,[ ] containing a curious zoophyte called graptolite in great abundance, and a few shells." on the journey also he found much to interest a geologist--boulders almost everywhere, some of huge size, lying on the surface or scattered in the sand in one place an outcrop of cretaceous greensand, full of belemnites, which were popularly regarded as "witches' candles." then over a picturesque granite region--"a country of rock, fir-wood, and peasants"--till he arrived at norrköping, and made his way in a steamer down one fjord and up another until he came into the malar lake. these last stages introduced him to a kind of scenery of which scandinavia affords such striking and innumerable examples--the margin of a submerged mountain land. "we entered," he says, "a passage between an endless string of islets and the mainland, the water here smooth as a millpond. we passed swiftly on in deep water close to the rocks, on the barest of which are a few firs in the clefts. these are evidently the summits of submarine mountains." at stockholm he found plenty to be done. some of the evidence, which had been brought forward to prove a rising of the land, was obviously weak. for instance, on one of his first visits to a place where the upward movement was said to be comparatively rapid, he found a fine oak-tree, perhaps a couple of centuries old, growing eight feet above high-water mark, and thus indicating either that oak-trees had recently changed their habits or that the change of level had been slow. "in dealing with this question it is necessary," he writes, "to cross-examine both nature and man. the testimony of the former is strong; of the latter, i must say, so weak and contradictory that i require to know the men and find how they got their views." a valuable precaution this, which might be remembered with advantage in days when stay-at-home geologists are far too numerous. if this were done, the paper currency of the science would be considerably reduced in quantity, and there would be a closer correspondence between its real and its nominal value. a little scepticism was certainly justifiable, for one would-be _savant_ stood him out "that a bed of _cardium edule_ (the common cockle) feet high proves that the _fresh water_ of lake malar was once that much higher." lyell adds nothing to this remark, but his silence is eloquent. this expedition, however--to södertelje--gave results yet more striking than marine shells feet above the present level of the baltic. "what think you," he writes, "of ships in the same formation, nay, a _house_? it is as true as the temple of serapis.[ ] i do not mean that i discovered all this, but i shall be the first to give a geological account of it. i am in high spirits at the prize." upsala also, to which he next moved, increased his stores of knowledge and of fossils. "i went to the hill, a hundred feet high, on which the tower stands, to examine marine shells. all of baltic species. you remember that in the half-hour between the two steamboats at lübeck, or rather travemunde, i collected shells by the quay. not one fossil have i found newer than the chalk in sweden, that was not in the number of those found living in that half-hour." more localities for shells were visited, erratics were examined, and pilots were questioned closely "about the agency of ice, in which they believe." with their opinion lyell inclined to agree; at any rate, he was convinced that his observations would "quite overset the _débâcle_ theory," and, as he expected, "bring in ice carriage as the cause." on the coast further north at oregrund and gefle, bench-marks had been cut some years previously in order to apply a more exact test to the question of the change in levels. these he visited, and the former seemed to prove "as galileo said in a different sense, that 'the earth moves.'" the marks near gefle afforded similar testimony, so that he felt now that the main object of his journey was accomplished, and inserted this pregnant note in his journal:--"i feel now what i was very sensible of when correcting my last edition,[ ] that i was not justified in writing any more until i had done all in my power to ascertain the truth in regard to the 'great northern phenomenon,' as the gradual rise of part of sweden has been very naturally called. you will see by-and-by how important a point it was, and how materially it will modify my mode of treating the science, and how much it will advance the theory of the agency of existing causes as a key to explain geological phenomena."[ ] but the work at sea-marks was not yet quite ended, and there was besides another classic spot to be visited--uddevalla, between lake werner and the western coast. here are deposits in which sea-shells are abundant at a height of about two hundred feet above the sea. nothing but a submergence can account for their presence, for polyzoa and barnacles are found attached to the solid rock. some of the latter, adhering to the gneiss, were collected by lyell on this occasion.[ ] fossil shells (of existing species) were so numerous that, he says, the deposit was worked for making lime, and he compares it with a well-known bed in the tertiaries of the paris basin. the shells, however, at uddevalla, as he points out, are not of that brackish-water character peculiar to the baltic, but such as now live in the northern ocean.[ ] on reaching the coast he made an expedition by boat, and saw the bench-mark at gullholmen, and rocks which had emerged from the sea within the memory of people still living. here, by way of completing his work, he "hired the services of a smith to make a mark at the water's edge:-- c. . l. ------ . . ." ----------- so he brought his journey in scandinavia to a close, and by the end of july had reached kinnordy, where mrs. lyell awaited his coming. then he set to work to prepare a brief sketch of his investigations for the approaching meeting of the british association in edinburgh, and a more elaborate paper, to be communicated to the royal society in london, in which he set forth the reasons which had convinced him that in sweden, "both on the baltic and ocean side, part of that country is really undergoing a gradual and insensibly slow rise." it affects an area measuring about one thousand miles north and south, and is believed to reach a maximum at the north cape. there it is said, but the statement needs verification, to amount to five feet in a century; at gefle, ninety miles north of stockholm, it cannot be more than two or three feet in the same time; while at stockholm itself it can hardly exceed six inches. further south, in scania proper, as at malmö, skanör, trelleborg, and ystad, the movement is distinctly in an opposite direction.[ ] this paper was afterwards accepted by the royal society as the bakerian lecture for the year. but the preparation of this was not lyell's only occupation. in october he had begun fossil ichthyology, was attending lectures in chemistry, and "had made some progress," as he writes to mantell, "in a single volume which two years ago i promised murray, a purely elementary work for beginners in geology, and which i find more agreeable work than i had expected." so his hands were pretty full. a pleasant surprise came in the closing months of the year, namely the award of one of the royal medals by that society in acknowledgment of the merits of his "principles of geology." in the earlier part of lyell accepted the presidency of the geological society, an office which, it will be remembered, he had virtually refused a couple of years before, when he was busy with his great book. with this exception, nothing worthy of record appears to have happened in the first six months of the year, but in july mrs. lyell and he left england for a journey to france, germany, and switzerland. by that date, as he mentions in a letter to a friend, , copies of the last edition of the "principles" had been sold, a demand that puts him in good heart as to the future of the book, and proves that his labours on it had not been in vain. but he did not permit himself to be idle. as a letter written to sedgwick from paris shows, he was still working away at the classification of the tertiary deposits; for in this letter he discusses the relation of the coralline and the red, or shelly crag of suffolk. mr. charlesworth, subsequently well known as a collector, had been obtaining a number of fossil shells from the former deposit, and the character of these suggested that it was distinctly the older of the two, as is now universally admitted. in discussing this question lyell lays down a principle of classification the soundness of which has been proved by experience, namely, that the age of a tertiary deposit is to be determined by the proportion of recent species and the relation of these to the forms still living in the neighbouring seas. if, for instance, the recent shells in a formation, amounting to one-half, or even as few as one-third, of the total number can be thus found, the formation will be pliocene in age, "while the recent shells of the miocene have a more exotic and tropical form." to this conclusion he had been led, by an examination, with the help of deshayes, of a typical collection of crag fossils which he had carried with him to paris. as to other matters, the leading french geologists were still warring vigorously in defence of deluges, and none of his numerous heresies, he remarks, appears "to have excited so much honest indignation as his recent attempt to convey some of the huge scandinavian blocks to their present destination by means of ice." he had proved, he reminds sedgwick, that "some of the great blocks near upsala must have travelled to their present destination since the baltic was a brackish water sea, so that those who maintain that there was one, and one only, rush of water, which scattered all the blocks of sweden and the alps, must make out this catastrophe to be, as it were, an affair of yesterday." geology, even at that date, had advanced far enough for this admission to have landed the diluvialists in some awkward dilemmas, to say nothing of the physical difficulties which they would find in accounting for the existence of waves or currents potent enough to bowl the _pierre à bot_ from the aiguilles round the trient glacier to the slopes of the jura, or to fling the erratics of scandinavia broadcast over the lowlands around the baltic. this, however, was not the only lost cause over which the french geologists were holding their shield. lyell goes on to write, with a touch of quiet sarcasm: "as to the elevation crater business, von buch, de beaumont, and dufresnoy are to write and prove that somma and etna are elevation craters, and von buch himself has just gone to auvergne to prove that mont dore is one also." lyell's special intention in visiting the alps was to obtain evidence as to the relation of the metamorphic and sedimentary rocks. geologists of the wernerian school, with sundry others who hardly went so far as the freiberg professor, maintained that the crystalline schists, including gneiss, had been produced, often as precipitates, in a primæval ocean, the waters of which were far too hot to allow of the existence of life. at a later time, as the temperature fell, the great masses of slightly altered slates and grits were deposited--the region of "greywacke," the transitional rocks as they were commonly called. these for the most part were unfossiliferous, at any rate in their earliest stages. to this view, of course, the huttonian dictum, which lyell sought to establish, was diametrically opposed, viz. that the earth showed no signs of a beginning. now he had been informed that in the alps certain slaty rocks contained fossils which indicated an age corresponding generally with the chalk of england, and that in other parts of that chain even crystalline schists could be found interbedded with fossiliferous strata of secondary age. to settle the former question he intended to visit the famous quarries of glarus, but was ultimately compelled to leave this for another year, as he took the latter point first in order of time, and the investigation of it involved more work than he had anticipated. in regard to this, the most important sections were to be found on the precipitous northern slopes of the jungfrau and in the upper part of the urbach-thal, a lonely glen which descends into the main valley of the aar at imhof, above meyringen. in both these localities gneiss appears to overlie "fossiliferous limestone," and lyell, after visiting them, returned satisfied that he had seen "alternations of the gneiss with limestone of the lias or something newer in the highest regions of the alps." that undoubtedly he saw, but he did not suspect that the appearance was illusory. this was not in the least surprising; the alps were still almost a terra incognita; the processes of "mountain making" as yet were unknown; many statements in common currency as to the passage of sedimentary into crystalline rocks were erroneous and distinctly misleading. only by degrees was it discovered that this superposition of gneiss or crystalline schist to secondary rock was due to folding on a scale so gigantic that the older had been doubled over upon the younger rock and the apparent order of succession was the converse of the true one. the intercalation also of the gneiss and the jurassic limestone was a result of a similar action, but carried, if possible, to an even greater extreme, for here the hard gneiss had been thrust in wedge-like slabs between the softer masses of sedimentary rock, like a paper-knife between the leaves of a book; that is to say, the gneiss and crystalline schists in both cases were vastly more ancient than the fossiliferous limestone. it is only of late years that this startling fact has been established beyond question; and even now there are many geologists who do not appear to recognise how seriously the huttonian _dictum_ "there is no sign of a beginning" has been shaken by the collapse of this evidence. at the present time the question is in this position; all the attempts to prove crystalline schists to be of the same age as, or younger than, fossiliferous sedimentary rocks either have been complete failures or have proved to be very dubious, while in many cases these schists are demonstrably earlier than the oldest rocks of the district to which a date can be assigned. hence, though possibly it may turn out that the disciples of hutton were right, and that, as lyell thought, a metamorphic rock may be of almost any geological age, his hypothesis not only is unproved, but also the evidence which has been brought forward in its favour has turned out after a strict scrutiny to be exceedingly dubious, if not absolutely contrary. in regard to this question we may feel a little surprise that one difficulty did not occur to lyell's sceptical mind, namely: what could be the nature and cause of a process of metamorphism which could convert one sediment into a crystalline schist--changed practically past recognition--and leave its neighbour so far unaltered that its characteristic fossils could be readily recognised? but though he was unable to investigate the question of secondary or perhaps early tertiary fossils in the "transition"-like rock of glarus, his study of the sedimentary deposits of the bernese oberland, which had formed a necessary preliminary to the other inquiry, raised some difficulties in his mind as to the origin of slaty cleavage. at a meeting of the geological society in the month of march, professor sedgwick had read his classic paper[ ] on this subject, in which he established the independence of cleavage and bedding. this paper laid the foundation for the discovery of the true cause of the former structure, though its author was unable, with the information then at his command, to do more than suggest an hypothesis, which afterwards proved to be incorrect. he had shown that both the strike and the dip of cleavage-planes were persistent over large areas, and that while the one might gradually change its direction and the other its angle of inclination, if they were followed far enough, yet this angle usually remained unaltered for considerable distances, and appeared to be quite unaffected by any variation in the slope of the strata. from these observations it followed that the planes of cleavage ought not to be coincident with those of bedding. lyell, however, writes to tell sedgwick[ ]:-- "i found the cleavage or slaty structure of fine drawing slate in the great quarry of the niesen, on the east [south] side of the lake of thun, quite coincided with the dip of the strata ascertained by alternate beds of greywacke.... as it is the best description of drawing slate, and as divisible almost as mica into thin plates, i cannot make out how to distinguish such a structure from any which can be called slaty, and such an attempt would, i fear, involve the subject in great confusion." the observation was perfectly correct, and many like instances could be found in the alps; nevertheless, sedgwick was right in his generalisation, and the two structures are perfectly independent, though the difficulty raised by lyell did not disappear till the true cause of slaty cleavage was recognised--viz. that it is a result of pressure. thus, in a region like the alps, where the strata often have been so completely folded as to be bent, so to say, back to back, the planes of cleavage, which are produced when the rocks can no longer yield to the pressure by bending, necessarily coincide with those of bedding. still, even in these cases, if careful search be made in the vicinity, some minor flexure generally betrays the secret, and exhibits the cleavage structure cutting across that of bedding. the next year, , flowed on, like the last, quietly and uneventfully; a fifth edition of the "principles" was passing through the press; the "elements of geology" was making progress, though slowly; and lyell's duties as president of the geological society, which involved the delivery of an address in the month of february and the preparation of another one for the same season in the following year, occupied a good deal of his time. the summer was spent in a long visit to his parents at kinnordy, after which he and mrs. lyell made some stay in the isle of arran before they returned to london. the latter seemingly had been rather out of health, and this may have been the reason why a longer journey was not undertaken, but she must have found the scotch air a complete restorative, for after her return to london in the autumn lyell writes to his father that "everyone is much struck with the improvement in mary's health and appearance." but one letter, of the few which have been preserved from those written in , possesses a special interest, for it expresses his ideas, at this epoch, in regard to the question of the origin of species, and indicates his freedom from prejudice and the openness of his mind. it is addressed to sir john herschel, then engaged in his memorable investigations at the cape of good hope, who had favoured him with some valuable comments and criticisms on the principles of geology, and in the course of these had corrected a mistake which lyell had made in regard to a rather difficult physical question. in referring to this, the latter remarks that the clearness of the mathematical reasoning (to quote his words) "made me regret that i had not given some of the years which i devoted to greek plays and aristotle at oxford, and afterwards to law and other desultory pursuits, to mathematics." doubtless there is hardly any better foundation for geology than a course of mathematics; at the same time, classical studies did much to give lyell his lucidity and elegance of style, and thus to ensure the success of the "principles of geology." it will be best to give lyell's own words, for the document forms an appendix or lengthy postscript. as is incidentally mentioned, it was not in his own handwriting,[ ] and thus probably was drawn up with rather more than usual care. "in regard to the origination of new species, i am very glad to find that you think it probable it may be carried on through the intervention of intermediate causes. i left this rather to be inferred, not thinking it worth while to offend a certain class of persons by embodying in words what would only be a speculation.... when i first came to the notion--which i never saw expressed elsewhere, though i have no doubt it had all been thought out before--of a succession of extinction of species, and creation of new ones, going on perpetually now, and through an indefinite period of the past, and to continue for ages to come, all in accommodation to the changes which must continue in the inanimate and habitable earth, the idea struck me as the grandest which i had ever conceived, so far as regards the attributes of the presiding mind. for one can in imagination summon before us a small part[ ] at least of the circumstances which must be contemplated and foreknown, before it can be decided what powers and qualities a new species must have in order to enable it to endure for a given time, and to play its part in due relation to all other beings destined to coexist with it, before it dies out. it might be necessary, perhaps, to be able to know the number by which each species would be represented in a given region , years hence, as much as for babbage to find what would be the place of every wheel in his new calculating machine at each movement. "it may be seen that unless some slight additional precaution be taken, the species about to be born would at a certain era be reduced to too low a number. there may be a thousand modes of ensuring its duration beyond that time; one, for example, may be the rendering it more prolific, but this would perhaps make it press too hard upon other species at other times. now, if it be an insect it may be made in one of its transformations to resemble a dead stick, or a lichen, or a stone, so as to be less easily found by its enemies; or if this would make it too strong, an occasional variety of the species may have this advantage conferred upon it; or if this would be still too much, one sex of a certain variety. probably there is scarcely a dash of colour on the wing or body, of which the choice would be quite arbitrary, or what might not affect its duration for thousands of years. i have been told that the leaf-like expansions of the abdomen and thighs of a certain brazilian mantis turn from green to yellow as autumn advances, together with the leaves of the plants among which it seeks for its prey. now if species come in in succession, such contrivances must sometimes be made, and such relations predetermined between species, as the mantis for example, and plants not then existing, but which it was foreseen would exist together with some particular climate at a given time. but i cannot do justice to this train of speculation in a letter, and will only say that it seems to me to offer a more beautiful subject for reasoning and reflecting on, than the notion of great batches of species all coming in, and afterwards going out at once." early in october charles darwin, for whose return from his noted voyage on the _beagle_ lyell had more than once expressed an earnest desire, arrived in england, bringing with him a large collection of specimens and almost innumerable facts, geological and biological, the fruits of his travels. the biological observations slowly ripened in darwin's mind till they had for their final result the "origin of species." the geological stirred lyell to immediate enthusiasm, for they afforded a valuable support to some of the ideas which he had put forward to the "principles." "the idea of the pampas going up," he writes to darwin, "at the rate of an inch a century, while the western coast and andes rise many feet and unequally, has long been a dream of mine. what a splendid field you have to write upon!" the enthusiasm evidently was not confined to words, for darwin himself says in writing to professor henslow, "mr. lyell has entered in the most good-natured manner, and almost without being asked, into all my plans."[ ] the letter to darwin,[ ] which is quoted above, also contains a characteristic piece of advice. "don't accept any official scientific place if you can avoid it, and tell no one i gave you this advice, as they would all cry out against me as the preacher of anti-patriotic principles. i fought against the calamity of being president [of the geological society] as long as i could. all has gone on smoothly, and it has not cost me more time than i anticipated; but my question is, whether the time annihilated by learned bodies ('par les affaires administratives') is balanced by any good they do. fancy exchanging herschel at the cape for herschel as president of the royal society, which he so narrowly escaped being, and i voting for him too! i hope to be forgiven for that. at least, work as i did, exclusively for yourself and for science for many years, and do not prematurely incur the honour or the penalty of official dignities. there are people who may be profitably employed in such duties, because they would not work if not so engaged." not very altruistic advice, it may be feared, but nevertheless bearing the stamp of practical wisdom. committee-work and other official duties are terrible wasters of time, and thus, although often necessary and inevitable, are rightly regarded as evils. many men, as lyell intimates, have been seriously hindered in researches for which they were exceptionally fitted by allowing themselves to be at everyone's beck and call, and getting their days cut to shreds by meetings. so far has this gone in some cases, that the high promise of early days has been very inadequately fulfilled, and some great piece of work has been never completed. if the spirit in which lyell writes were more frequent, the common illusion that workers in science belong to some inferior branch of the public service would be dispelled, and the business of scientific societies would sometimes run more smoothly; at any rate, it would be finished more quickly, because no one would care to waste time over splitting hairs, and hunting for knots in a bullrush.[ ] the year , like the preceding one, was spent in quiet work, though three months of the summer were devoted to a journey on the continent. as regards the former, it is evident that the book on which he was engaged had caused him more than ordinary difficulty, for it appears to have progressed more slowly than can be explained either by the duties of the presidential chair, which he resigned in the month of february of this year, or by any distraction caused by other scientific work. but a sentence in a letter written to one of his sisters at the beginning of may throws some light on the cause of the delay. he says, "i have at last struck out a plan for the future splitting of the 'principles' into 'principles' and 'elements' as two separate works, which pleases me very much, so now i shall get on rapidly." the summer journey was to denmark and the south of norway, and this time mrs. lyell was able to bear him company. they left london early in june for hamburg, crossing holstein to kiel, and travelling thence to copenhagen. here he set to work at once with dr. beck to study fossil shells, in the crown prince's cabinet and in the other museums of the city. questions had arisen as to the nomenclature of various fossil species to which lyell had referred in his book, on which dr. beck differed from deshayes, so that lyell was anxious to investigate some of the points for himself, and to see the original type-specimens in linnæus' collection, since these, in some cases, had been wrongly identified by lamarck and other palæontologists. during a drive with the crown prince, he had the opportunity of examining an interesting section of the drift a few miles from copenhagen, where it "was composed to a great depth of innumerable rolled blocks of chalk with a few of granite intermixed. fossils were numerous in the chalk.... prince christian set four men to work, while the horses were baiting, to clear away the talus, by which i saw that the boulders of chalk were in fact in beds, with occasional layers of sand between." on reaching norway lyell made several expeditions from christiania, in the course of which he examined a clay which occupies valleys and other parts of the granite region. this, which sometimes is found more than feet above sea-level, he states "is a marine deposit containing recent species of shells, such as now inhabit the fjords of norway." this visit to norway gave lyell the opportunity of dispelling some erroneous ideas as to the relation of the granite to the "transition" (or lower palæozoic) strata. this granite he found to be intrusive into these rocks, and into the much more ancient gneiss on which they rested. the sedimentary rocks near the junction were much altered, the limestones being changed into marble, the shale into micaceous schists; the fossils being more completely obliterated in the latter than in the former case. some remarks which he makes as to the relations of the granite and gneiss indicate the closeness and carefulness of his observations. "this gneiss ... this most ancient rock is so beautifully soldered on to the granite, so nicely threaded by veins large and small, or in other cases so shades into the granite, that had you not known the immense difference in age, you would be half-staggered with the suspicion that all was made at one batch."[ ] from copenhagen, on their return, they went to lübeck and drove thence to hamburg, across the sand and boulder formation of the baltic, and so through the north of germany. among these boulders lyell recognised the red granite, which he had seen in norway sending off veins into the orthoceratite limestones and associated silurian rocks. this "had been carried, with small gravel of the same, by ice of course, over the south of norway, and thence down the south-west of sweden, and all over jutland and holstein down to the elbe, from whence they come to the weser, and so to this or near this (wesel-on-the-rhine). but it is curious that about münster and osnabruck, the low secondary mountains have stopped them; hills of chalk, muschelkalk, old coal, etc., which rise a few hundred feet in general above the great plain of north and north-west germany, effectually arrest their passage. this then was already dry land when holstein, and all the baltic as far as osnabruck or the teutoberger waldhills, was submerged."[ ] at the end of september they returned to london through paris and normandy, and the rest of the year was mainly devoted to the completion of the "elements of geology." little seems to have happened in the earlier part of the next year ( ); and in the summer lyell went northward, halting on the way, at newcastle-on-tyne, to attend the meeting of the british association. here he was made president of the geological section, which appears to have been very successful, for he writes that the section was crowded--from , to , persons always present. the meeting, altogether, was a large one; but as the total number of tickets issued only amounted to , , it seems probable that the general public was admitted more freely than is the custom at the present day. sedgwick also on one occasion attracted a large crowd, for we are told that he delivered a most eloquent lecture "to , people on the sea-shore." geology, no doubt, has made great advances since that day, little more than half a century ago, but at the cost of much loss of attractiveness. it was then simple in its terminology, and fairly intelligible to people of ordinary education; now these are frightened away by papers bristling with technical terms and greek-born words, and nothing but the prospect of a "scrimmage" would draw together people to a meeting of section c at the present day. commonly the audience hardly amounts to one-fifth of that number. geologists, perhaps, might consider with advantage whether a little abstinence from long words might not make the science more generally intelligible, and thus more attractive, without any loss of real precision. the "elements of geology" was finally published a few weeks before the newcastle meeting, and the work of recasting the "principles" went on at intervals in preparation for the sixth edition, which appeared in . if, in accordance with the maxim, a nation is happy which has no history, lyell ought to have passed almost a year in a state of felicity, for nothing is recorded between september th, , when he writes to charles darwin from kinnordy, and august st, , when he writes to dr. fitton from the same place. both these letters are interesting. the former discusses the relation of darwin's theory of the formation of coral islands with e. de beaumont's idea of the contemporaneity of parallel mountain chains, which has been already mentioned. one passage also throws light upon the difficulties with which the british association in its earlier days had to contend. some of the most influential newspapers had set themselves to write it down--needless to say, without success. good sense sometimes is too strong even for newspapers. but lyell thus urges darwin[ ]:-- "do not let broderip, or the _times_ or the _age_ or _john bull_, nor any papers, whether of saints or sinners, induce you to join in running down the british association. i do not mean to insinuate that you ever did so, but i have myself often seen its faults in a strong light, and am aware of what may be urged against philosophers turning public orators, etc. but i am convinced--although it is not the way i love to spend my own time--that in this country no importance is attached to any body of men who do not make occasional demonstrations of their strength in public meetings. it is a country where, as tom moore justly complained, a most exaggerated importance is attached to the faculty of thinking on your legs, and where, as dan o'connell very well knows, nothing is to be got in the way of homage or influence, or even a fair share of power, without agitation." far-reaching words, the truth of which has been demonstrated again and again during the years which have elapsed since they were written. lyell lays his finger on the weakest spot in the nature of the true-born briton: he is deaf to quiet reasoning, and frightened by loud shoutings. the second letter, that of , is addressed to dr. fitton, who had written for the _edinburgh review_ a criticism of the "principles of geology," in which he had expressed the opinion that lyell had insufficiently acknowledged the value of hutton's work. from this charge lyell defends himself, pointing out that, valuable as were hutton's contributions to the philosophy of geology, he was by no means the first in the field--that there were also "mighty men of old" to whom he felt bound to do justice, even at the risk of seeming to undervalue the great scotchman. he points out that hutton's work occupies a fair amount of space in the section of the "principles" which is devoted to an historical sketch of the earlier geologists:-- "in my first chapter," he writes, "i gave hutton credit for first separating geology from other sciences, and declaring it to have no concern with the origin of things;[ ] and after rapidly discussing a great number of celebrated writers, i pause to give, comparatively speaking, full-length portraits of werner and hutton, giving the latter the decided palm of theoretical excellence, and alluding to the two grand points in which he advanced the science--first, the igneous origin of granite; secondly, that the so-called primitive rocks were altered strata.[ ] i dwelt emphatically on the complete revolution brought about by his new views respecting granite, and entered fully on playfair's illustrations and defence of hutton.... the mottoes of my first two volumes were especially selected from playfair's 'huttonian theory' because--although i was brought round slowly, against some of my early prejudices, to adopt playfair's doctrines to the full extent--i was desirous to acknowledge his and hutton's priority. and i have a letter of basil hall's, in which, after speaking of points in which hutton approached nearer to my doctrines than his father, sir james hall, he comments on the manner in which my very title-page did homage to the huttonians, and complimented me for thus disavowing all pretensions to be the originator of the theory of the adequacy of modern causes."[ ] in the following month lyell attended a meeting of the british association at birmingham, and was invited, together with several of the leading men of science there present, to dine and spend the night at drayton manor, the residence of sir r. peel, near tamworth. in a letter to one of his sisters, lyell gives an interesting sketch of his impressions of the great statesman:-- "some of the party said next day that peel never gave an opinion for or against any point from extra-caution, but i really thought that he expressed himself as freely, even on subjects bordering on the political, as a well-bred man could do when talking to another with whose opinions he was unacquainted. he was very curious to know what vernon harcourt [the president for that year] had said on the connection of religion and science. i told him of it, and my own ideas, and in the middle of my strictures on the dean of york's pamphlet[ ] i exclaimed, 'by-the-bye, i have only just remembered that he is your brother-in-law.' he said, 'yes, he is a clever man and a good writer, but if men will not read any one book written by scientific men on such a subject, they must take the consequences.' ... if i had not known sir robert's extensive acquirements, i should only have thought him an intelligent, well-informed country gentleman; not slow, but without any quickness, free from that kind of party feeling which prevents men from appreciating those who differ from them, taking pleasure in improvements, without enthusiasm, not capable of joining in a hearty laugh at a good joke, but cheerful, and not preventing lord northampton, whewell, and others from making merry. he is without a tincture of science, and interested in it only so far as knowing its importance in the arts, and as a subject with which a large body of persons of talent are occupied."[ ] the next year ( ) appears to have slipped away uneventfully, for only a single letter serves as a record for the twelvemonth, and that is but a short one addressed to babbage asking him to look up one or two geological matters during a journey through normandy to paris. as it is dated from london on the th of august, this looks as if lyell did not go during the summer farther than scotland, where he presided over the geological section at the meeting of the british association.[ ] the earlier part of appears to have been equally uneventful; but the summer of that year saw the beginning of a long journey and the opening of a new geological horizon, for mr. and mrs. lyell crossed the atlantic on a visit to canada and the united states. footnotes: [ ] at king's college and at the royal institution. _see_ pp. , . [ ] life, letters, and journals, vol. i. p. . [ ] huxley, "man's place in nature," p. . [ ] only the skull was found, and that imperfect; moreover, the missing part could not be discovered. the same is true of the other animal remains, so that they could hardly have been victims of the deluge. [ ] "man's place in nature," p. . [ ] _turbo littoreus_, _mytilus edulis_, _cardium edule_. [ ] the term, of course, is used here in the sense of either a slaty rock or a hard shale. [ ] the ruins of which (in the bay of baiæ) gradually sank after the middle of the fifth century until (probably towards the end of the fifteenth century) the floor was more than twenty feet under water. since then it has risen up again.--"principles of geology," chap. xxx. [ ] he had expressed his doubts, in this and the former editions, as to the validity of the proofs of a gradual rise of land in sweden. [ ] life, letters, and journals, vol. i. p. . [ ] lyell's specimens appear to have come from kured, two miles north of uddevalla, and only one hundred feet above the sea, but barnacles were obtained by brongniart at two hundred feet.--"principles of geology," chap. xxxi. [ ] "antiquity of man," chap. iii. [ ] "principles of geology," ch. xxxi. "antiquity of man," ch. iii. [ ] "on the structure of large mineral masses," etc. _trans. geol. soc. lond._, iii. p. . [ ] life, letters, and journals, vol. i. p. . [ ] the weakness of his eyes was always more or less of a trouble. [ ] it is "past" in the text (life, letters, and journals, vol. i. p. ), but i think this an obvious misprint. [ ] "life of charles darwin," vol. i. p. . [ ] life, letters, and journals, vol. i. p. . [ ] it is but rarely that, so far as the writer has seen, this remark applies to the committees of scientific societies in london, but the amount of time thus wasted in the universities, judging from his own experience of one of them, is really melancholy. [ ] life, letters, and journals, vol. ii. p. . [ ] _ibid._, vol. ii. p. . [ ] life, letters, and journals, vol. ii. p. . [ ] though undoubtedly this severance of geology and cosmogony was very helpful at the time to the progress of the former, the justice of it may be questioned; and lyell's approval would not be endorsed by every geologist at the present day, though probably it would still commend itself to the majority. [ ] while this is true of many of the so-called primitive rocks, it is now generally believed that no inconsiderable portion are really abnormal or modified igneous rocks. [ ] life, letters, and journals, vol. ii. p. . [ ] the very reverend w. cockburn, d.d., who testified against the association in a pamphlet entitled "the dangers of peripatetic philosophy" (published in ). when the association met at york in , he read a paper before the geological section, criticising that science, and propounding a cosmogonical theory of his own. he was severely handled by professor sedgwick, but published his paper under the title, "the bible defended against the british association." this, though an exceptionally silly production, had a large sale. ("life and letters of sedgwick," vol. ii. p. .) [ ] life, letters, and journals, vol. ii. p. . [ ] held at glasgow, beginning september th. an allusion, however, during his american journey seems to imply a visit to france this year. chapter vii. geological work in north america. this is a summary of their doings on the opposite side of the atlantic in lyell's own words: "in all, we were absent about thirteen months, less than one of them being spent on the ocean, nearly ten in active geological field work, and a little more than two in cities, during which i gave by invitation some geological lectures to large and most patient audiences." to this may be added "three dozen boxes of specimens," and a mass of notes on the raised beaches of the canadian lakes, the glacial drift, the falls of niagara, and other questions of post-tertiary geology, as well as on the tertiary, cretaceous, coal, and older rocks. these afterwards produced a crop of about twenty papers, which appeared in various scientific periodicals. the principal results and the general impressions of the journey were worked up into a book entitled "travels in north america," which was published in . a geologist who has been trained among the scenery of britain finds his first view of the alps to be the beginning of a new chapter in the book of nature, but a visit to america more like the beginning of a new volume. there almost everything is on a colossal scale--rivers, lakes, forests, prairies, distances, such as cannot be matched, at any rate in the more accessible parts of europe. one may read of plains where the sun rises and sets as from a sea; of lakes, like superior, as big as ireland; of falls, like niagara, where the neighbouring ground never ceases to quiver with the thud of the precipitated water; of rivers well nigh half a league wide while their waters still are far from the sea. but such things must be seen to be realised. in our own island nature seems to be working at the present time on a scale comparatively puny; she must be watched as she puts forth her full strength before the adequacy of modern causes can be duly appreciated, and the history of the past can be understood by comparing it with that of the present. the invitation to cross the atlantic hardly could have reached lyell at a more opportune epoch of his life. in his forty-fourth year, he was in full vigour both of mind and of body. a long course of study and of travel in europe had trained him to be a keen observer, had enabled him to appreciate the significance of phenomena, and had supplied him with stores of knowledge on which he could draw for the interpretation of difficulties. america also offered a splendid field for work. much of the country had been settled and brought under cultivation at no distant date; new tracts were being made accessible almost daily. geologists of mark were few and far between, so that large areas awaited exploration, and in many places the traveller found a virgin field. the geological survey of canada was just then being organised, the labours of the national survey in the united states had not yet begun, though state surveys were at work, and had already borne good fruit. indeed, while lyell was in the country, the third meeting of the association of american geologists was held at boston, and among those present were several men whose names will always occupy an honoured place in the history of the science. still, at almost every step the observer might be rewarded by some discovery or by some fascinating problem which would give a direction to his future work. the lyells left liverpool on july th, , and reached halifax on the st of the month, whence they went on to boston, arriving there on august nd. the close resemblance of the shells scattered on the shore at the latter place to those in a similar situation in britain was one of the first things which lyell noted; for he found that about one-third were actually identical, a large number of the remainder being geographical representatives, and only a few affording characteristic or peculiar forms. for this correspondence, which, as he writes, had a geological significance, he was not prepared. the drifts around boston, good sections of which had been exposed in making cuttings for railways, resembled very closely the deposits which he had seen in scandinavia. were it not, he says, for the distinctness of the plants and of the birds, he could have believed himself in scotland, or in some part of northern europe. these masses of sand and pebbles, derived generally from the more immediate neighbourhood, though containing sometimes huge blocks which had travelled from great distances, occasionally exceeded feet in depth. commonly, however, they were only of a moderate thickness, and were found to rest upon polished and striated surfaces of granite, gneiss, and mica-schist. the latter effects, at any rate, would now be generally attributed to the action of land ice, but lyell thought that the great extent of low country, remote from any high mountains, made this agent practically impossible, and supposed that the work both of transport and of attrition had been done during a period of submergence by floating ice and grounding bergs. after a few days' halt at boston, they moved on to newhaven, where professor silliman showed him dykes and intrusive sheets of columnar greenstone altering red sandstone, their general appearance and association recalling salisbury crags and other familiar sections near edinburgh. in this district lyell found the grasshoppers as numerous and as noisy as in italy, watched the fireflies sparkling in the darkness, and had his first sight of a humming-bird, and of a wildflower hardly less gorgeous, the scarlet lobelia. from newhaven they went to new york, and up the hudson river in one of the great steamers, past the noble colonnade of basalt called the palisades, and along the winding channel through the gneissic hills to albany. here a geological survey had been established by the state, and its members had already done good work, which, however, was not altogether welcome to its employers, for they had dispelled all hopes of finding coal within the limits of the state. this, as lyell says, was a great disappointment to many; but it did good in checking the rashness of private speculation, and in preventing the waste of the large sums of money which had been annually squandered in trials to find coal in strata which really lay below the carboniferous system. the advantage to the revenues of the state by the stoppage of this outlay and the more profitable direction given to private enterprise were sufficient, lyell remarks, "to indemnify the country, on mere utilitarian grounds, for the sum of more than two hundred thousand dollars so munificently expended on geological investigation." from albany lyell travelled to niagara. the journey was planned in order to give him an opportunity of examining a connected series of formations from the base of the palæozoic, where it rested on the ancient gneiss, to the coalfield of pennsylvania; and he had the great advantage of being accompanied by one of the most eminent of american geologists, mr. james hall. "in the course of this third tour," lyell writes,[ ] "i became convinced that we must turn to the new world if we want to see in perfection the oldest monuments of the earth's history, so far as relates to its earliest inhabitants. certainly in no other country are these ancient strata developed on a grander scale, or more plentifully charged with fossils; and as they are nearly horizontal, the order of their relative position is always clear and unequivocal. they exhibit, moreover, in their range from the hudson river to the niagara some fine examples of the gradual manner in which certain sets of strata thin out when followed for hundreds of miles; while others, previously wanting, become intercalated in the series." he observed, also, that while some species of the fossils contained in these rocks were common to both sides of the atlantic, the majority were different; thus disproving the statement which at that time was often made--namely, that in the rocks older than the carboniferous system the fossil fauna in different parts of the globe was almost everywhere the same, and showing that, "however close the present analogy of forms may be, there is evidence of the same law of variation in space as now prevails in the living creation." lyell made a thorough study of the falls of niagara, to which he paid a second visit before his return to england. the first view of these falls, like the first sight of a great snow-clad peak, is one of those epochs of life of which the memory can never fade. it stirred lyell to an unwonted enthusiasm. at the first view, from a distance of about three miles, with not a house in sight--it would be impossible, we think, to find such a spot now; "nothing but the greenwood, the falling water, and the white foam"--he thought the falls "more beautiful but less grand" than he had expected; but, after spending some days in the neighbourhood, now watching the river sweeping onwards to its final plunge, here in the turmoil of the rapids, there in its gliding, so smooth but so irresistible; now gazing at that mighty wall of 'shattered chrysoprase' and rainbow-tinted spray, which floats up like the steam of etna; now looking down from the brink of the crags below the fall upon those rapids, where the billows of green water roll and plunge like the waves of the ocean, he "at last learned by degrees to comprehend the wonders of the scene, and to feel its full magnificence." but, keenly as he might be impressed with the poetic grandeur of the falls, he could not forget the scientific questions which were ever present to his mind. the gorge of niagara offered a problem for solution which had for him a special fascination. not only did it illustrate on a grand scale the potencies of water in rapid motion, but also it furnished data for estimating the period during which this agent had been at work. the gorge has been carved in a plateau of silurian rock, which terminates, seven miles below the falls, in a precipitous escarpment overhanging queenstown. there was a time when that gorge did not exist, when the river first took its course along the plateau on its way from lake erie, and plunged over the brink of the escarpment. the valley at first was nothing more than a shallow trench excavated in the drift which covers the surface of the country--such an one as may still be seen between lake erie and the falls--but the river, slowly and steadily, has cut its way back through the rocky plateau from the first site of the falls near queenstown to their present position. the upper part of this plateau consists of a thick bed of hard limestone, but beneath this the deposits become softer; and the lowest bed is the most perishable. the water, as it plunges down, undermines the overlying rock. the gorge began at once to be developed, and it has ever since continued to retreat towards lake erie. every year makes some slight change. this becomes more marked when old histories are consulted and old drawings compared with the present aspect of the scene. father hennepin's sketch, of which lyell gives a copy,[ ] rude and incorrect as it is, proves beyond all question that the changes in the neighbourhood of table rock have been very considerable, for it shows that on this side a third and much narrower cascade fell athwart the general course of the main mass of water. this cascade, by the time of kalm's[ ] visit in , had ceased to be conspicuous, and had quite disappeared before the date of lyell's visit. the horseshoe fall also at the present time is less worthy of the name than it was at that date, for its symmetry has been seriously marred by a deep notch which the northern stream has cut in the more central part of the curve.[ ] careful inquiry convinced lyell that the slow recession of the falls was an indubitable fact, and that its rate, on an average, was about a foot a year. as the gorge is about seven miles long, this would fix its beginning about , years ago.[ ] from niagara falls they travelled, still in mr. hall's company, by buffalo to geneva, examining on the way some red, green, and bluish-grey marls, with beds of gypsum and occasional salt springs, which, though older than the coal measures of england, closely resembled in appearance the upper part of the new red sandstone of britain. finally, after crossing the outcrops of the devonian system, they reached pennsylvania, where lyell obtained his first view of the coal measures of north america, and was no less interested than surprised to find how closely the whole series corresponded with that of britain. he saw sandstones "such as are used for building in newcastle or edinburgh, dark shales often full of ferns 'spread out as in a herbarium,' beds and nodules of clay-ironstone, seams of bituminous coal, varying in thickness from a few inches to some yards, and, beside these, an underlying coarse grit, passing down into a conglomerate, which was very like the millstone grit of england. the underclays beneath the seam of coal were full of stems and rootlets of stigmaria, and the sight of these confirmed him in the opinion that the coal was formed of the remains of plants which had grown upon the spot."[ ] after examining the district, they returned to albany, and went thence to new york and philadelphia, picking up on the way as much geological information as was possible. new jersey afforded some highly interesting sections of rocks belonging to the cretaceous system, for these, though in mineral character resembling the greensands on the eastern side of the atlantic, contained fossils which corresponded more closely with those of the white chalk, some species being actually identical. this fact was another proof that, though there had been in past ages a general similarity in the fauna of any period, geographical provinces had existed no less than they do at the present time. lyell had examined, as mentioned above, the bituminous coals in the undisturbed region of pennsylvania, the next step was to study the beds of anthracite, with the associated strata, in the folded and broken ridges of the alleghany mountains. in this part of his work he had the inestimable advantage of being guided by professor h. o. rogers, whose name is inseparably connected with the geology of that classic region. the alleghanies or appalachians consist of a series of silurian, devonian, and carboniferous strata in orderly sequence, "folded" (to use lyell's words) "as if they had been subjected to a great lateral pressure when in a soft and yielding state, large portions having afterwards been removed by denudation. the long uniform, parallel ridges, with intervening valleys like so many gigantic wrinkles and furrows, are in close connection with the geological structure," and the rocks are most disturbed on the south-eastern flank of the chain, where the folds sometimes bend over to the west; in other words, the greatest disturbances are on the side nearest to the fundamental gneiss and the basin of the atlantic--facts which probably stand in the relation of effect and cause. it was a surprise to lyell, on reaching the anthracite district around pottsville on the schuylkill, to see "a flourishing manufacturing town with the tall chimneys of a hundred furnaces, burning night and day, yet quite free from smoke." special contrivances, of course, are requisite to secure the combustion of anthracite, especially in household fireplaces, but he had no hesitation in declaring that he preferred the use of it, notwithstanding the stove-like heat produced, to that of the bituminous coal consumed in london, with the penalty of living in an atmosphere dark with smoke and foul with smuts. the seams of anthracite in this district are sometimes worked in open-air excavations, but as the strata have been bent into a vertical position the beds above and below, when the anthracite has been quarried out, are left like the walls of a fissure, and thus can be examined with the greatest ease. here also the "roof" of the seam proved to be a dark shale full of the usual plant-remains, among which were some british species of ferns, and the "floor" was an "underclay" containing the stems and rootlets of stigmaria. lyell also observed that the beds of detrital materials--sandstones, shales, etc.--were less persistent than those of coal, and that the way in which the former became thicker towards the south-east indicated that this was the direction of the ancient land region from which they had been derived. the result of his examination satisfied him that the anthracite of the appalachians was identical in age, generally speaking, with the bituminous coal which he had previously examined, and was merely a fragment of the great continuous coalfield of pennsylvania, virginia, and ohio, which lies about forty miles away to the westward. after returning to philadelphia mr. and mrs. lyell went, _viâ_ new york, to boston, where he had been engaged to deliver a course of twelve lectures on geology at the lowell institute. to the courses here admission was free, but the tickets were given under certain restrictions. for lyell's lectures about , were issued, and the class, he states, usually consisted of more than , persons. it had therefore to be sub-divided and each lecture to be repeated. the audience was composed "of persons of both sexes, of every station in society, from the most affluent and eminent in the various learned professions to the humblest mechanics, all well-dressed, and observing the utmost decorum." at the conclusion of the lectures the lyells travelled southwards, so that he might take advantage of the more genial climate and continue his geological work in the open air. he first halted at richmond in virginia, and from that place visited the tertiary deposits in the vicinity of the james river. the more interesting of these are of miocene age, and he observed that the fossils of maryland and virginia resembled those of touraine and the neighbourhood of bordeaux more closely than those from the coralline crag of suffolk, especially in the presence of genera indicative of a warm climate. from this place they travelled across the "pine barrens"--where their train was stopped for the night by the slippery condition of the rails--to weldon in north carolina. here lyell saw the great dismal swamp, a morass which extends for about forty miles from the neighbourhood of this town to norfolk in virginia. like the bogs of ireland, this marshy plain, some five-and-twenty miles across, is rather higher at the middle than at the edges. its surface "is carpeted with mosses, and densely covered with ferns and reeds, above which many evergreen shrubs and trees flourish, especially the white cedar (_cupressus thyoides_), which stands firmly supported by its long tap-roots in the softest parts of the quagmire. over the whole, the deciduous cypress (_taxodium distichum_) is seen to tower with its spreading top, in full leaf, in the season when the sun's rays are hottest, and when, if not interrupted by a screen of foliage, they might soon cause the fallen leaves and dead plants of the preceding autumn to decompose, instead of adding their contributions to the peaty mass. on the surface of the whole morass lie innumerable trunks of large and tall trees, blown down by the winds, while thousands of others are buried at various depths in the black mire below. they remind the geologist of the prostrate position of large stems of sigillaria and lepidodendron, converted into coal in ancient carboniferous rocks."[ ] at charleston they had practically passed beyond the southern limit of the winter snowfall, the greatest enemy of the field-geologist, and could carry on work without fear of interruption. here they found flowers "at the end of december still lingering in the gardens," and were in the region of the palmetto palm. few things during this rather lengthy journey impressed lyell more than the facility of locomotion in a district which, comparatively speaking, was a new settlement, and was still in places thinly peopled, together with the general good quality of the accommodation for travellers. in this respect they had fared much worse during the previous year, when they were travelling through some of the more populous parts of france, such as touraine and brittany. after a journey through the pinewoods, they reached augusta in georgia, where another group of tertiary deposits invited a halt. those belonging to the eocene period lie further down the savannah river, so that a journey was made for the purpose of examining them, in the course of which, near the town of the same name as the river, lyell also saw the clay in which remains of the mastodon and of other extinct mammals had been found. the muddy beach, with the tracks of racoons and opossums, gave him some hints as to the history of fossil footprints, so that on the whole very much interesting geology was the reward of a three weeks' stay in south carolina. then they once more turned their faces northward, and made their way, working at geology as they went, to philadelphia, where they found themselves again in the region of colder winters at the present, and of erratic boulders as memorials of the past. six weeks were spent in philadelphia, but lyell's time was largely taken up by the delivery of a short course of lectures on geology. pennsylvania, however, added to his experiences in another way, for the state had passed through a commercial crisis, and was unable to pay the interest on its funded debt. the soreness produced by this repudiation will not be readily forgotten, for nearly two-thirds of the stock--the whole amount of which was eight millions sterling--was held by british owners, so that the loss was felt heavily on this side of the atlantic. in his "travels" lyell gives a brief history of this transaction, and discusses the political causes of a crisis which had been hardly less disastrous in america than in england. they reached new york in the month of march, and spent several weeks there, for in that neighbourhood both the ancient crystalline rocks and the modern drift, with its erratics, afforded lyell ample materials for study, each of these being then reckoned (and they have not ceased to be so counted) among the most difficult questions of geology. towards the middle of april he proceeded northward, in order to examine the perplexing schists and less altered sedimentary deposits of the taconic range, rocks which from that time to this have given ample employment to geologists. after this he found an opportunity of making use of the lessons learnt on the flats by the james river, for he went to springfield and examined the famous footprints in the sandstone of connecticut. as the deposit was referred to the trias, and the footprints to birds, they were supposed to indicate the existence of this class of the animal kingdom at the beginning of the secondary era. they have, however, now lost their special interest, since they are generally assigned to reptiles. after the middle of april was past, the travellers again reached boston, from which city an excursion was made in order to study the tertiary deposits of the island called martha's vineyard, off the coast of massachusetts. returning to philadelphia early in may, they went by baltimore westward to the valley of the ohio, in order to examine the undisturbed country beyond the folded district of the alleghany mountains. by this journey another section was, in fact, run across the great coalfield of the eastern states, but considerably to the south of that which had been examined in the autumn of the preceding year. this proved no less interesting than the former one. at brownsville, to take one instance only, a seam of bituminous coal, ten feet in thickness, was seen cropping out in the river cliff by the side of a large tributary of the ohio, where it was worked by horizontal galleries. pittsburg and other interesting localities in the neighbourhood were also visited, and then the lyells descended the ohio river to cincinnati. he had thus traversed in descending order the succession of strata from the carboniferous to the lower silurian or ordovician system, which is exposed in the neighbourhood of that town. this, however, was not the only attraction offered by cincinnati. some two-and-twenty miles distant is the famous big bone lick in kentucky. here some saline springs break out on a nearly level and boggy river plain, which are still attractive to wild animals, and often in past time lured them to their death in the adjacent quagmires. here the bones of the mastodon and the elephant, of the megalonyx, stag, horse, and bison, have all been found, some in great numbers; and the last-named animals had frequented the springs within the memory of persons who were living at the time of lyell's visit. these bones are generally embedded in a black mud, at a depth of about a dozen feet below the surface of the creek. lyell suggests that very probably the heavy mastodons and elephants were lost by shoving one another off the tracks and into the more marshy ground as they struggled to satisfy themselves at the springs; just as horses, cattle, and deer get pushed into the stream in thronging to the rivers on the pampas of south america. from cincinnati the travellers struck northward to cleveland on lake erie, going across a region which at that time was still being cleared and settled, and getting an experience of that american form of travellers' torture called a corduroy road. the lake-ridges--curious mounds or terraces of water-worn materials--in the neighbourhood of cleveland afforded a new subject for an investigation which was continued in the vicinity of ontario. but before reaching this lake lyell spent a week at the falls of niagara, revising and enlarging the work already done. during the time he investigated the buried channel which appears to lead from the whirlpool to st. davids, a league or so to the west of queenstown. this was supposed by lyell and many subsequent geologists to indicate part of an old course of the st. lawrence, which had afterwards been blocked up by glacial drifts. it is, however, according to professor j. w. spencer, only a branch of a buried valley, outside the niagara cañon and much shallower than it, which has been cut through by the present st. lawrence, and has merely produced an elongation of the chasm at the whirlpool.[ ] another series of lake-ridges was examined in the neighbourhood of toronto. here lyell traced them to a height of feet above the level of ontario, seeing in all no less than eleven, some of them much reminding him of the ösar which he had examined in sweden. in regard to these lake-ridges he writes thus:-- with the exception of the parallel roads or shelves of glenroy and some neighbouring glens of the western highlands in scotland, i never saw so remarkable an example of banks, terraces, and accumulations of stratified sand and gravel, maintaining, over wide areas, so perfect a horizontality, as in the district north of toronto.[ ] leaving toronto on june th, they descended the st. lawrence to montreal and quebec. the neighbourhood of either town afforded opportunities for much interesting work, especially in the drift deposits; the underlying ice-worn surfaces of crystalline or palæozoic rock reminding lyell of what he had seen in scandinavia. at montreal, the great hill, which gives its name to the town built upon its lower slopes, affords some highly interesting sections. it is composed of palæozoic limestone, which has been pierced by more than one mass of coarsely crystalline intrusive rock and cleft by many dykes of a more compact character. near the junction with the larger intrusive masses the limestone becomes conspicuously crystalline, and the fossils disappear, just as in the cases which lyell had already seen about the border of granite in scandinavia. some also of the igneous rocks now possess a further interest, for they contain nepheline, a mineral not very common. this, however, had not been recognised at the time of lyell's visit. the limestone in some of the quarries is wonderfully ice-worn, and the overlying drifts are in many ways remarkable. of these drifts, lyell examined various sections, at heights of from to feet above the st. lawrence, finding plenty of sea-shells,[ ] the common mussel being in one place especially abundant. he also examined some sections of stratified drifts between montreal and quebec, but without obtaining any fossils, though they had been found by captain bayford and others. the drifts, however, near the latter city were more prolific. with their shells, indeed, he was already, to some extent, familiar, for in the year he had received a collection from captain bayford. this happened to reach london at a time when dr. beck of copenhagen was with him, and "great was our surprise," he writes, "on opening the box to find that nearly all the shells agreed specifically with fossils which, in the summer of the preceding year, i had obtained at uddevalla in sweden." the most abundant species were still living in northern seas, some in those of greenland and other high latitudes; while in sweden they were found fossil between latitudes ° and ° n., and here in latitude °. these fossil shells occur at beaufort, about a league below quebec, and about a quarter of a mile from the river, in deposits which have filled an old ravine in the palæozoic rock. a laminated clay forms the lowest bed, above which comes a stratified sand, and this is followed by a clay containing boulders, each of these deposits being about twenty-five feet thick. they are without fossils, which begin with the next bed, a stratified mass of pebbly sand and loam, and become more frequent, till at last this passes into a mass nearly twelve feet thick, consisting almost wholly of the well-known bivalve _saxicava rugosa_. this deposit was about feet above the level of the sea. afterwards, in travelling southwards from montreal, whither he returned from quebec, lyell found marine shells on the border of lake champlain, about eighty miles from the former town. here they occurred in a loam, which was covered by a sand, and rested on a clay about thirty feet thick, containing boulders, some of them nine feet in diameter. lyell sums up the results of his investigations by stating that, in his opinion, the shells certainly belong to the same geological period as do the boulders, and occur both above and below beds containing erratics; while the fundamental rocks below the drift are "smoothed and furrowed on the surface by glacial action." this effect lyell at that time attributed to the friction of bergs grounding as they floated, but it is now referred by the majority of geologists to the action of land ice. be this, however, as it may, the shell-bearing beds must have been deposited in the sea; so that either the land must have sunk as the ice retreated, or the latter at the time of its greatest extension must have trespassed on the domain of the sea, as it still does around parts of the antarctic continent. from montreal they went, by way of lake champlain and over the green mountains, to boston, where they arrived about the middle of july, and proceeded by steamer to halifax. here began the last stage of lyell's journey, the examination of the carboniferous system in nova scotia, to which work a full month was devoted. after studying the gypsum, red marl, and sandstone of the lower part of that system, which bears some resemblance to the upper trias (keuper) of britain, he crossed the bay of mines to minudie, in the heart of the nova scotian coalfield. the cliffs by the sea-shore exhibit a fine series of sections, from the gypseous rocks up to the coal measures, uninterrupted by faults, the beds dipping steadily at an angle of nearly °. sandstones, shales, and seams of coal could be seen alternating in the usual manner; and from the last-named, stumps of trees, sometimes two or three yards high, were seen in places, as at south joggins, projecting at right angles to the surface of the bed. of such stems he observed at least seventeen at ten different levels. the stumps never pierced a coal-seam, but always terminated downwards either in it or in shale, and never in sandstone, thus indicating that they were a part of the vegetation from which the coal had been formed, and that it, like a peat-bog in england, required a subsoil impervious to water. lyell also mentions that mr. (now sir) j. w. dawson, who was his companion for part of the time, had found a bed of calamites in a similar position of growth. but, in addition to much interesting work in various parts of the nova scotian coalfield, lyell had the opportunity of witnessing the noted tides of the bay of fundy, where the difference between high and low water is as great as, if not greater than, anywhere else on the globe. on the muddy flats thus left bare he had another opportunity of studying the tracks left by various animals, marine and terrestrial; and in watching how these were hardened by the action of the sun, if they had been made near the high-water mark of spring-tides, he gained further hints for interpreting the fossil footprints of connecticut and other countries. on the th of august the lyells left halifax for england, thus bringing to a close a year of assiduous field-work, long journeys, and varied experiences. it was a period of the most continuous outdoor labour, and thus the most fruitful in the acquisition of knowledge which he had spent since his marriage and the publication of the "principles of geology"--a period comparable only with his journey, between may, , and february, , in france, italy, and sicily, though it was still longer and more fruitful, were this possible, in varied geological experiences. he had not, indeed, seen in this part of america any volcanoes, active or extinct--of which, however, he had already examined plenty; but he had studied good and characteristic sections of almost every formation which occurred in the more eastern states of america, from the most ancient crystalline masses, the foundation stones of the continent, to the most recent fossiliferous drifts. he had travelled from a region which resembled scandinavia to one where the climate was more like that of the north coast of africa, and had enlarged his conceptions of the scale on which nature worked. but, in addition, he had been afforded an opportunity of studying the social and political condition of a young and vigorous nation as it was developing, unfettered by antiquated laws and hereditary customs. to this aspect of the tour a brief reference will be made in a later chapter; now it is enough to say that the long journeying of the twelvemonth had been happily ended, without illness, without the slightest accident, without anything that could be called an adventure. this good fortune followed them to the very end, for even the homeward passage is dismissed with the brief remark that it took nine days and sixteen hours; so that it may be supposed to have been prosperously uneventful. then in eight hours after leaving liverpool the travellers were back once more in london. footnotes: [ ] "travels in north america," chap. i. [ ] "travels in north america," chap. ii. [ ] see the plate in the _gentleman's magazine_, . [ ] see map in "man and the glacial period," by dr. g. f. wright (international scientific series), p. . [ ] the estimates made by geologists have varied from , years (ellicott, in ) to not more than , years (united states geological survey, ). professor j. w. spencer, who has recently investigated the question, has arrived, by a different method, at a date practically identical with that assigned by lyell (proc. roy. soc., vol. lvi. ( ), p. ). [ ] this was still a moot point with geologists. lyell refers to the confirmatory evidence which w. logan had recently obtained in the south wales coalfield of britain. [ ] "principles of geology," chap. xliv. [ ] proc. roy. soc. lvi. ( ), p. . [ ] the lake-ridges and raised beaches around the great lakes, indicating margins of the water when it stood at a higher level than now, have received much attention of late years from canadian and american geologists. they are found to vary somewhat in level, thus indicating unequal movements of the earth's crust. references to literature prior to will be found in a paper by professor j. w. spencer, quart. jour. geol. soc., vol. xlvi. ( ), p. . [ ] see, for descriptions of these sections and lists of the fossils, sir w. dawson's "the ice age in canada," chaps. vi. and vii. they occur up to feet above the sea. chapter viii. another epoch of work and travel. very soon after their arrival in england the travellers went north to kinnordy, where they remained till the end of october, when they returned again to their london home. such an accumulation of specimens and of notes as had been gathered in america made necessary a long period of labour indoors, unpacking, classifying, and arranging; while certain groups of fossils had to be repacked and sent to friends, who had undertaken to work them out. these occupations apparently detained lyell in london till august, , when he started for ireland, indulging himself on the way with a short run in somersetshire for some geological work around bath and bristol, examining more particularly the "dolomitic conglomerate," a shore deposit of keuper age, in which the remains of saurians had been found, and the radstock collieries, where he spent more than five hours underground "traversing miles of galleries in the coal," and finding here, as he had done in america, the stumps of trees in an upright position and shales full of fossil ferns as "roofs" to the seams. then, in company with mrs. lyell, he crossed over to cork, where the british association assembled on august th, under the presidency of the late earl of rosse. the meeting was well attended by scientific men, but was coldly received by the neighbourhood and county--partly, as lyell says, because the gentry cared little for science; partly because the townspeople, comprising many rich merchants and most of the tradesmen, were "repealers"; "and, the agitation having occurred since we were invited, the opposite parties could never, in ireland, act or pull together." it was impossible to visit cork without seeing the beauties of the lakes and mountains of killarney; and after this a short stay was made at birr castle, lord rosse's pleasant home at parsonstown. the huge reflecting telescope, which is now more than a local wonder, was not then completed; but the smaller one, itself on a gigantic scale, was in full working order, and already had led to grand results by "not only reducing nebulæ into clusters of distinct stars, but by showing that the regular geometric figures in which they presented themselves to herschel, when viewed with a glass of less power, disappear and become very much like parts of the milky way." thence they went northward to the coast of antrim, to see the waves breaking upon the colonnades of basalt at the giant's causeway, and the dykes of that rock cutting through and altering the white chalk. evidently the geology proved interesting, as well it might, for here nature presents a volume of her geological history, that of the secondary era, with only the opening and the concluding chapters, all the record from the early part of the lias to the beginning of the cretaceous having been torn out. the dark-tinted greensand, changing almost immediately into the pure white chalk, often presents curious colour-contrasts in a single section; while the classification of the several deposits offered a problem at which probably lyell thought it wiser to "look and pass on." several of the more interesting facts observed during this trip were afterwards described in the "elements of geology,"[ ] among them the beds of lignite which occur in antrim, associated with the great flows of basalt. somewhat similar deposits were found, about seven years later, at ardtun, in mull, by the duke of argyll--a discovery which led lyell to suggest, in later editions of the above-named work, the probability that the basalts of antrim and of the inner hebrides were of the same geological age,--an inference which since then has been abundantly confirmed by the researches of professor judd and other geologists. one of the most interesting sections in scotland faces antrim. here, on the ayrshire coast, between girvan and ballantrae, a complex of several kinds of igneous rock and a region, not a little disturbed, of "greywackes" and other sedimentary deposits present the geologist with problems more than sufficiently perplexing. at these lyell took the opportunity of glancing, but a day's trip afforded no opportunity for any serious attempt to read the riddle. that had to be left to a later generation, and so it remained for over forty years. something is now known about the igneous rocks, though here work still remains to be done; and the sedimentary deposits have been brought into order by the labours of professor lapworth. they exhibit, according to his description,[ ] an ascending succession from the llandeilo to the llandovery group, and appear to be more modern than some, if not all, of the above-named igneous rocks. after their brief halt in this district the lyells went on to forfarshire, and spent the rest of the autumn at kinnordy. the winter was a busy time; he was writing steadily at his "travels in north america," and working up some of the more distinctly scientific notes into formal papers for the geological and other societies. thus occupied, more than a year slipped away, diversified only by a summer visit to scotland, attending the meeting of the british association at york, and a journey to the haswell colliery, durham, together with faraday, as commissioners to examine into the cause of a recent disastrous explosion, and see whether such accidents could be prevented. work at the "travels in north america" took up all lyell's spare time during the winter, and the book was published in the earlier part of . it was only a few months old when mr. and mrs. lyell again set off for another tour in america. they left liverpool on september th, and landed at halifax on the th, after a voyage diversified agreeably by the sight of an iceberg and disagreeably by two gales. they went on at once to boston, and thence made a tour through the state of maine. during this sundry masses of drift were examined, which rested on polished and grooved surfaces of crystalline rock, and contained the usual shells, astarte, cardium, nucula, saxicava, etc., and in some places a fossil fish[ ] in concretionary nodules. at portland similar shells had been found in drifts which also contained bones both of the bison and of the walrus. these drifts in some places attained a thickness of feet, and in them valleys feet deep had been excavated by streams. then they went to the white mountains, and on approaching them lyell did not fail to notice "on the low granite hills many angular fragments of that rock, fifteen to twenty feet in diameter, resting on heaps of sand." on their way they came to the willey slide, where a whole family of that name had been killed nineteen years previously in a landslip. lyell carefully examined the scene of the accident, in order to ascertain what effects were produced by a mass of mud and stones as it slid over a face of rock, and found that it only made short scratches and grooves, not long and straight furrows, like those left by a glacier. they halted at fabyan's hotel near mount washington, and after waiting for a favourable day reached the summit ( , feet above the sea) on october th. it is easily accessible on horseback. the notes of this excursion among the mountains show that lyell still retained his old liking for natural history in general, for they contain remarks on the flowers, the insects, and the birds. some observations on the alpine flora of the higher summits in the white mountains indicate his position at that time in regard to the origin of species. he adopts the hypothesis of 'specific centres,' viz. that "each species had its origin in a single birthplace and spread gradually from its original centre to all accessible spots, fit for its habitation, by means of the power of migration given it from the first." he supposed that the plants common to the more arctic regions and to the higher ground further south in europe and northern america were dispersed by floating ice during the glacial epoch, when the ground stood at a lower level, and that afterwards, when the climate became warmer, they gradually mounted up the slopes of the hills. the possibility of a migration by land is not mentioned, though doubtless it would have been admitted, because the evidence which he had so often studied pointed rather to a downward than to an upward movement but he asserts with some emphasis that many living species are older than the existing distribution of sea and land. on his return to boston, he had other opportunities of studying ice-worn rocks and erratics, and from this city made an excursion to plymouth (massachusetts) to see the spot where, on a mid-winter day, the pilgrim fathers had landed. but even here he could not neglect the shells upon the strand, and he records that eighteen species were collected, one-third of which were common to europe. still, we may note that on this journey rather more attention was paid than on the former to questions political, commercial, educational, and theological, and these occupy a larger space in the "second visit to the united states," which may account for its greater popularity. for example, it contains a sketch of the witch-finding mania in massachusetts late in the seventeenth century, and a whole chapter on the sea-serpent. this "hardy perennial" had appeared in the gulf of st. lawrence in the previous august and in october, ,[ ] and had repeatedly visited the new england coast from to , when it had been seen by many credible witnesses. lyell appears to be satisfied that, though allowance had to be made for exaggeration and honest misconception, some big creature had been seen, and suggests that it may have been an exceptionally large specimen of the basking shark.[ ] after a stay of nearly two months in boston, they left for the south early in december, and found a little difficulty at first, as on a former occasion, from the slippery state of the rails. they journeyed by newhaven, new york, philadelphia, and washington to richmond, where a halt was made to examine the coalfield some sixteen miles to the south-west of the city. the measures rest on the granite, filling up inequalities on its surface, and are occasionally cut by dykes, which produce the usual alteration in the adjacent coal. the principal seam is from thirty to forty feet thick but the field, as a whole, reminded lyell most of that at st. etienne (france), which he had visited in .[ ] from richmond they went, as on the former occasion, by weldon to wilmington, where the cliffs near the town yielded some tertiary fossils, and on christmas morning they landed from a steamer at charleston. from this city lyell again visited the deposits near savannah, which contained remains of megatherium, mastodon, and other large quadrupeds, as well as a second locality on skiddaway island, and then, on the last day of the year, quitted charleston for darien in georgia. here also were some more deposits of the same kind, while at st. simon's island lyell examined a very large indian mound. it was a mass of shells, chiefly of oysters, and contained flint arrow-heads, stone axes, and fragments of indian pottery. returning to savannah, they travelled towards the north-west, by macon to milledgeville. for more than miles of the first part of the journey lyell went along the railway on a hand-car, so as to study the cuttings and obtain the most continuous section possible of the tertiary deposits from the sea to the inland granite. these deposits consisted of porcelain clays, yellow and white sands, and "burrstone," a flinty grit used for millstones, which often was full of silicified shells and corals, with the teeth of sharks and the bones of zeuglodon. lyell mentions that in the neighbourhood of macon he saw blockhouses such as those described by cooper in the "pathfinder," which twenty-five years earlier had been used for defence against the indians before any white men's houses had been built in the forest. near milledgeville the granite, gneiss, etc., is decomposed _in situ_ to a considerable depth, and the rain-water, when the trees have been cut down, quickly furrows the detrital deposits of the neighbourhood. a remarkable instance of this action had occurred at pomona farm, where a ravine feet broad and feet deep had been excavated in the course of only twenty years.[ ] from milledgeville they returned to macon, and thence travelled westward by columbus to montgomery, being much jolted in the stage-coach, but securing as a reward some tertiary fossils; and at the latter place they found red clays and sandstones, which, however, were about the same age as the chalk of england. after the coach travelling, a journey by steamer down the alabama river to mobile was a welcome change, and the not unfrequent halts for cargo or to take in wood gave opportunities for collecting fossils from the neighbouring bluffs. one night they were startled by loud crashing noises and the sound of breaking glass, and found that the steamer had run foul of the trees growing on the bank. their branches touched the water, as the river was unusually high; and the vessel, in the darkness, had been steered too near to the shore. longer halts were made at claiborne, to collect fossils from deposits corresponding in age with those at bracklesham in england; and at macon (alabama) to visit a place where some remarkable specimens of the zeuglodon had been discovered. from mobile also a long river journey was undertaken to tuscaloosa, to visit a coalfield which supplied the town with fuel and the materials for gas. the field, "a southern prolongation of the great appalachian coalfield," is a large one, being about ninety miles long and thirty wide, with some seams sixteen feet thick worked in open quarries. he remarks that he made geological excursions "through forests recently abandoned by the indians, and where their paths may still be traced." the strata on the alabama river afforded a useful lesson on the variability of lithological characters. were it not for the fossils, lyell says, the lower cretaceous beds of loose gravel might be taken for the newest tertiary, the main body of the chalk for lias, and the soft tertiary limestone for the representative of the chalk. it was impossible to leave mobile without seeing something of the gulf of mexico; so they went in a steamer down the alabama river to the seaside, looked upon the muddy banks, with the shells[ ] which live in them and the quantities of drift-timber which bestrew them, and then went across to one of the minor mouths of the mississippi, and, passing up it, landed at new orleans. this town, about miles by water from the confluence of the main channel of the mississippi with the sea, afforded a convenient opportunity for studying the character of the lower part of the delta of the "father of waters." such a region might be expected to supply facts which would be helpful in the interpretation of many phenomena presented by the coal measures. accordingly, lyell made one excursion to lake pontchartrain, a great sheet of fresh water no great distance from both new orleans and the sea, and another down to the mouth of the mississippi. the road through the swamp to the former was constructed of a strange material--viz. the white valves of a freshwater mollusc.[ ] these are obtained from a huge bank over a mile in length, and sometimes about four yards in depth, at one end of the lake. how this had been formed seemed doubtful. possibly the shells had been piled up by the waves during a storm; possibly there had been some slight change of level. the lake itself is about fifteen feet below high-water mark, and is about as many deep; but, as it receives an arm of the mississippi, silt is gradually raising the bottom. the sea sometimes, when impelled by a strong south-east wind, makes its way into the lake. among the english coal measures--as, for instance, at coalbrook dale or in yorkshire--beds of marine shells are occasionally found intercalated among or even associated with freshwater molluscs, without any alteration in the general character of the beds in which they lie. how this might occur is illustrated by lake pontchartrain in the swampy alluvial delta. here a very slight physical change might enable the sea to take, for a time, possession of the land, and the denizens of its water, like a band of pirates, to dispossess the usual inhabitants. the other expedition also supplied not a few valuable facts relating to the history of river deltas, which were afterwards supplemented as they travelled northwards for some hundreds of miles up the river, following its sinuous course through leagues of marshy plain, densely overgrown with vegetation. in the seaward reaches, reed, and rush, and willow, but above new orleans cypresses and other timber trees, rise above the rank herbage. the minor channels, blocked with driftwood which formed natural rafts; the sand-bars and mud-banks; the great curves of the river, the "bayous"[ ] and isolated pools; the natural banks built up by the sediment arrested at flood-time by the herbage near the river brink; the floating timber and the "snags"--all provided valuable illustrations of the physical features of a great river delta, and supplied him with material which afterwards was worked up into newer editions of the "principles" and the "elements." from new orleans lyell went by steamer to natchez, halting on the way to examine more closely certain localities of interest and to obtain illustrations of how a coalfield might be formed. the bluffs of natchez--almost the first place where distinctly higher ground approaches the river-side--afforded plenty of semi-fossil shells, specifically identical with those still inhabiting the valley of the mississippi, but the loam in which they were embedded--a loam which reminded him of the loess of the rhine--also contains the remains of the mastodon, and overlies a clay with bones of the megalonyx, horse, and other quadrupeds, mostly extinct. beneath this clay are sands and gravel, the whole forming a platform which rises about feet above the low river plain, revealing an earlier chapter in the history of the river. similar bluffs occur at vicksburg, but these disclosed eocene strata beneath the alluvial deposits, and thus invited a halt in order to explore the neighbourhood. the next stage was to memphis, nearly miles. lyell speaks highly of the accommodation generally afforded by the river steamers, but found the inquisitiveness of his american fellow-travellers rather a nuisance, and the spoiled children a still greater one. the former drawback to pleasure has certainly abated during the last half-century, but whether the latter has done the same may perhaps be disputed. new madrid, miles above memphis, called for a longer halt, for the neighbouring district had suffered from a great earthquake in the year , when shocks were felt at intervals for about three months, the ground was cracked, water mingled with sand was spouted out, yawning fissures opened (in one case draining a lake), portions of the river cliff were shaken down into the stream, and a large district--about , square miles in area--was permanently depressed. some traces of the earthquake, in addition to the last-named, could still be recognised at the time of lyell's visit, though more than thirty years had elapsed. at cairo, above new madrid, the ohio joins the mississippi, and it was ascended to mount vernon. the geology now became a little more varied, for beneath the shelly loam already mentioned carboniferous strata make their appearance, in which fossil plants are sometimes abundant and upright trees now and then occur. for nearly miles higher up the ohio, rocks of this age are exposed at intervals, till at last, near louisville, those belonging to the devonian system rise from beneath them. these, at new albany, contain a fossil coral-reef, exposed in the bed of the river and crowded with specimens in unusually good preservation. at cincinnati the travellers came at last upon old ground, and journeyed thence by steamer to pittsburg. about thirty-two miles from this town, at a place called greensburg, some remarkable footprints had been discovered on slabs of stone not many months before lyell's visit, but as the beds on which they occurred belonged to the coal measures doubt had been expressed as to their being genuine, so he went thither to satisfy himself on this point. the footprints had disturbed the peace of pittsburg, for they had started discussions in which one party had assumed, as matters of course, the high antiquity of the earth and the great changes in its living tenants, and had thus incurred the censure--which in some cases was followed by professional injury--not only of the multitude, but also of some of the roman catholic and lutheran clergy. commenting on this episode, lyell quotes with approbation the words of a contemporary author,[ ] which even at the present time occasionally need to be remembered:--"to nothing but error can any truth be dangerous; and i know not where else there is to be seen so altogether tragical a spectacle, as that religion should be found standing in the highways to say 'let no man learn the simplest laws of the universe, lest they mislearn the highest. in the name of god the maker, who said, and hourly yet says, "let there be light," we command that you continue in darkness!'" the travellers crossed the alleghany mountains in their way to philadelphia. but a piece of work in virginia had been left unfinished on the last occasion--the examination of the jurassic coalfield near richmond. so he set off thither, leaving mrs. lyell in philadelphia, and took the opportunity of examining the tertiary deposits near the former town and the eocene strata on the potomac river. on his return they went to burlington, which they reached in the first week in may, just as the humming-birds were arriving in hundreds, and by the th of the month they were in new york. the age of the so-called taconic group--a question of which so much has been heard of late years--was then beginning to attract attention, so lyell went in company with some american geologists to albany in the hope of solving the problem. this he trusted he had done, but as his conclusions now would be deemed unsatisfactory, they need not be quoted. in reality, the question at that time was not even ripe for discussion. on the homeward journey he turned aside at boston to visit wenham lake, from which much ice was being supplied to london, and then they left for england by a steam packet which touched at halifax. four days after leaving this place they passed among a "group of icebergs several hundreds in number, varying in height from to feet," many of them picturesque in form, some even fantastic. stones were resting on one of them, but as a rule they were perfectly clean and dazzlingly white, except on the wave-worn parts, which, as usual, were a beautiful blue. these, and a fine aurora borealis on the next night, were the only incidents of the voyage, and on june th, in twelve and a half days from boston, the vessel reached liverpool. the close of this journey marks an epoch in lyell's life. it was the last--unless we except his visit to madeira--of his long wanderings for the purpose of questioning nature face to face, and of studying her under various aspects and diverse conditions. he did not, indeed, cease to travel. he twice returned to america, he revisited sicily and various parts of europe, but these journeys not only occupied less time but also led him among scenes for the most part not unfamiliar. he doubtless felt that on reaching his fiftieth year he might fairly regard the more laborious part of his education completed, although he never ceased to be a learner, even to the latest days of his life, when strength had failed and memory was becoming weak. an account of the above-named journey was published in , under the title of "a second visit to the united states of north america." this book, in addition to descriptions of the scenery and the geology of the country, contains much general information about the people, with remarks by the author on various political questions, such as the condition of parties, the effects of almost universal suffrage, particularly on the national sense of honour and morality, the existence and evils of slavery, the state of religious feeling, the position of churches, and the systems of education, especially when contrasted with those of england. some of these questions about this time were exciting much attention in great britain, and in regard to one matter--the delimitation of the territories of the two nations in the region west of the rocky mountains--friction existed, which was so serious that more than once war seemed possible. on this account, probably, the "second visit" was a greater success, commercially speaking, than the "travels," for it reached a third edition. footnotes: [ ] chapters xiv. and xxix. [ ] "the girvan succession," quart. jour. geol. soc., xxxviii. ( ), p. . [ ] the capelin (_mallotus villosus_), which still lives in the atlantic. [ ] it was also seen the following year on the coast of virginia, and on that of norway in both and . [ ] he says that the alleged sea-serpent washed ashore at stronsa (orkneys) in is proved by the bones (some of which are preserved) to have been this animal. [ ] the formation, however, does not belong to the carboniferous system, but is shown by its fossils to be jurassic in age. [ ] it is described and figured in later editions of the "principles of geology," chap. xv. (eleventh edition). [ ] a species of _gnathodon_. [ ] _gnathodon cuneatus._ [ ] a bayou is the name given to an old channel of the river. when the latter is making a series of horseshoe curves, the stream often cuts through the neck of land which separates its nearest parts. the water then takes the shortest course, the entrances to the old channel are silted up, and it becomes a horseshoe-shaped pool. [ ] t. carlyle ("letter on secular education"). chapter ix. steady progress. the "principles of geology" had been completed and published for thirteen years, yet catastrophism, as we learn from a correspondence with edward forbes,[ ] dated september, , was dying hard. "agassiz, alcide d'orbigny, and their followers [were still] trying to make out sudden revolutions in organic life in support of equally hypothetical catastrophes in the physical history of the globe."[ ] a remark in forbes's reply is striking:-- "you are pleased to compliment my paper on its _originality_. any praise from you must ever be among the greatest gratifications to me, and to any honest labourer in the great field of nature. but i had rather hear the views i have set forward be proved _not original_ than the contrary. it seems to me that the surest proof of the _truth_ of such conclusions as i have summed up at the end of my essay is the fact of their not being _original_ so far as _one_ person is concerned, and of their having become manifest to _more than one_ mind, either about the same time or successively, without communication. i believe laws discover themselves to individuals, and not that individuals discover laws. if a law have truth in it, many will see it about the same time." in this month also the lyells removed from hart street to , harley street. the house where they had spent fourteen years very happily was not left without regret, but it had become too small. they had no children, but a rapidly increasing geological collection takes up almost as much room as (though it is much more silent than) a growing family. the removal of a geological collection is a laborious business; and, besides this, lyell was preparing a new edition of the "principles" and writing a book about his recent travels in america. still, to judge from his letters, he found time for some pleasant social distractions; for his letters to the old home at kinnordy contain more often than formerly interesting references to talks with such men as macaulay, milman, and rogers, lord clarendon and lord lansdowne. the seventh edition of the "principles," condensed into a bulky single volume, was published early in , and in the following june lyell attended the meeting of the british association at oxford, which appears to have been no less pleasant than successful, although "out of twenty-four heads of houses only four were at oxford to receive the association." on this occasion, he writes, he became better acquainted with "ruskin, who was secretary of our geological section." the remainder of this summer was spent in scotland, and the rest of the year, with most of the following one, was devoted to quiet work. still, lyell took an active part in a crisis through which, about this time, the royal society was passing. a number of the fellows, including most of those eminent in science, were anxious to raise the standard for admission into the society. for many years past the "three letters" had often signified little more than an indication of good means and social position, coupled with a certain interest in scientific pursuits. the reformers prevailed, after a long struggle "with a set of obstructives compared with whom metternich was a progressive animal," and the present _status_ of the society is the result. incidental remarks in lyell's letters to his relations also indicate that he was becoming well known in circles other than scientific, of which a further proof was given in the autumn of , when he received the offer of knighthood. of course, in any country where "orders of merit" exist, other than great britain, lyell would have been "decorated" years ago, but we manage things differently. as a rule, we let science and literature be their own reward, and, as an exception, confer the same distinction on a man who has won a world-wide reputation (provided he is fairly rich) and on an opulent tradesman who is accidently prominent on some auspicious occasion, or is a local wirepuller in party politics. lyell went over from kinnordy to balmoral to receive the intended honour, and had, as he writes, "a most agreeable geological exploring on the banks of the dee, into which prince albert entered with much spirit." in february, , he was elected for the second time president of the geological society, and in the autumn, when at kinnordy, was again invited to balmoral, where he had some interesting talks with prince albert on subjects ranging from various educational and broad political questions to the entomology of switzerland, scotland, and the isle of wight. in the middle of september he attended the meeting of the british association at birmingham, where he was for the third time president of the geological section. a few weeks later his father, whose health had been for some time failing, died at kinnordy.[ ] the latter was a rich man, but as he made liberal provision for his daughters and younger sons, sir charles, though he succeeded to a considerable estate, found himself unable to afford the expense of keeping up kinnordy as well as a house in london. which, then, was henceforth to be his home? the attractions of kinnordy were obvious, but the long distance from the metropolis was a serious drawback, while the duties of a resident landlord would have interfered much with his geological work, which would have been still more hampered by the severance from libraries, museums, and intercourse with fellow-workers. thus he felt it his duty to retain his house in london and to let kinnordy, though, as his mother and sisters retreated to the "dower house," he was able from time to time to visit the old place. the decision probably was less painful than it otherwise would have been from the fact that his boyhood had been spent in england. at any rate, it was a wise one, in regard to both his own reputation and the progress of science in general. in the summer of , sir charles augmented his experience and refreshed old memories by a tour in germany. during this he saw for the first time the roth-todt-liegende or lower permian conglomerates at halle and at eisenach, as well as the great lava streams which had supplied them with so much of their materials. also he went to the brocken in order to examine into von buch's extraordinary assertion that the granite had "come up in a bubble." this, it is needless to say, was speedily pricked. the loess also, that singular deposit which wraps like a mantle so much of the undulating ground in northern germany, evidently engaged his attention, and we find the fruits of these studies in a later work. in addition to all this, he did more than glance at the maestricht chalk, the "wealden" coal of hanover, the tertiary deposits near berlin, the palæozoic rocks of the hartz, and the scenery of the saxon switzerland. his books, his scientific papers, and presidential addresses to the geological society, his duties as a commissioner, at first for the exhibition of , and somewhat later for the reform of the university of oxford, kept him pretty well employed till august, , when he for the third time crossed the atlantic to deliver another course of lectures at the lowell institute, boston. though he was back in england before christmas, he found time for some geological work in america, the most important item in which was an excursion from halifax in company with his old acquaintance, mr. j. w. dawson, to the nova scotian coalfield. on this occasion he passed through a fair amount of country still uncleared, which made the journey more interesting; he had also opportunities of appreciating the effects of ice in moving and piling up boulders on the shores of lakes, and obtained still more evidence in regard to this, on reaching the sea-coast in the neighbourhood of the coalfield. but their labour was rewarded by one discovery of exceptional importance. in the trunk of a tree which had died and become hollow in a forest of the carboniferous period, they found entombed the skeleton of an animal. whether this were a fish or a reptile was at first hotly disputed, but finally it proved to be an amphibian. on his return to england, sir charles was kept for some time fully employed by the preparation of the ninth edition of the "principles," but early in the summer of he went for the fourth time to america--on this occasion in company with lord ellesmere--as commissioner to the exhibition held at new york. but now his time was fully taken up by official duties, and his visit was a short one, for he returned before the end of july, and was soon afterwards invited to visit osborne and give some account of his journey to the queen and prince albert. very early in he again left england, in company with lady lyell and mr. and mrs. bunbury, to visit madeira. some three weeks were devoted to a careful study of the geology of that island,[ ] partly with the view of determining whether it afforded any support to von buch's favourite notion that volcanic cones were mainly formed by upheaval. as might be anticipated, the evidence was distinctly unfavourable. the island was proved to be mainly composed of volcanic material, cones of basaltic scoria, and great flows of similar lava, which had been piled successively one on another in the open air to a depth of about , feet. this mass had been subsequently pierced by dykes, worn by storm and stream, and in one or two places deeply grooved by rivers. there were, indeed, some underlying beds of marine origin, which, in one part of the island, rose to a height of , feet above the sea, and thus indicated a certain amount of upheaval; but even this was not of the kind which von buch's hypothesis required, while the rest of the evidence, including that afforded by some tuffs containing fossil plants, proved that the major part of the island had been formed above water. from madeira they went on to teneriffe, palma, and the grand canary. of this part of the journey few details are given, but the results were afterwards incorporated with one of his books.[ ] to the peak of teneriffe the reference is comparatively brief. of palma the account is much fuller, for this island had been regarded by von buch, who visited it in , as a type of his "craters of elevation"--an idea which was dispelled by lyell's investigation. the grand canary, like madeira, proved to be formed of masses of subaërial volcanic rock, perhaps even thicker than those in madeira, which also rested upon some upraised marine deposits of miocene age. in the course of sir charles received from his own university the honorary degree of d.c.l. much time was spent in working up the results of his last journey, some of which were communicated to the geological society.[ ] in the spring of he went to the continent, studying, among other matters, the drifts in the neighbourhood of berlin. in the summer he visited scotland, made the acquaintance of hugh miller, worked over arthur's seat, blackford hill, and "the coast of fife from kinghorn to kirkcaldy." it would be hard to find a set of sections better adapted for the study of ancient volcanic rocks, both contemporaneous and intrusive, than this coast affords; and his experience in madeira and the canaries enabled him to regard "the edinburgh and fife rocks with very different eyes." one or two of his published letters about this period have a special interest, for they show that his views on the origin of species were undergoing a gradual modification. speaking of some strange variations in the flower of an orchideous plant,[ ] he refers, half in jest, to "ugly facts, as hooker, clinging (like me) to the orthodox faith, calls these and other abnormal vagaries"; and again, the following sentences do not come from a man who is firm in his belief[ ]:-- "when huxley, hooker, and wollaston were at darwin's last week, they (all four of them) ran a tilt against species further, i believe, than they are deliberately prepared to go--wollaston least unorthodox. i cannot easily see how they can go so far, and not embrace the whole lamarckian doctrine. huxley held forth last week about the oxlip, which he says is unknown on the continent. if we had met with it in madeira and nowhere else, or the cowslip, should we not have voted them true species? darwin finds, among his fifteen varieties of the common pigeon, three good genera and about fifteen good species, according to the received mode of species and genus-making of the best ornithologists, and the bony skeleton varying with the rest! after all, did we not come from an ourang, seeing that man is of the old world, and not from the american type of anthropomorphous mammalia?" sir charles and lady lyell were again on the continent in the summer of , examining the drifts of northern germany, visiting humboldt at berlin, discussing geological questions, especially in regard to carboniferous plants, at breslau with roemer and goeppert; working over the riesengebirge; then going on to dresden, and passing through the saxon switzerland to aussig. the coalfield north-west of the former city was not neglected, the great breccia beds of the rothliegende were again examined, and account was taken of ramsay's opinion that certain british permian breccias were glacial in origin. close attention was also bestowed upon the great masses of hard quartzose grit, through which the elbe has carved its way--the quader of saxony; for this formation, "a grit wholly deficient in calcareous matter, corresponds to the more purely calcareous rock (chalk) of great britain, and yet contains here and there the same shells." he did not neglect the brown coal[ ] between töplitz and aussig, and, on reaching prague, made the acquaintance of barrande, who took him to see those older palæozoic rocks among which the great palæontologist had been labouring for nearly a quarter of a century. then the travellers proceeded to vienna, and after that to the styrian alps, to visit various interesting sections in the salzkammergut, such as the classic ground at gosau and the triassic limestones near hallstadt, where the last survivors of the palæozoic ages are entombed with the representatives of the period. his letters, like many others of earlier date, indicate that, notwithstanding the fascinations of geology, neither living molluscs, nor insects, nor plants had ceased to interest. they returned by way of munich, ulm, zürich and paris, reaching england about the end of october. the summer of was devoted to another continental tour, rather more restricted than the former, but by no means unimportant. they went leisurely through belgium and up the rhine into switzerland, halting at different places either to study sections of special interest or to confer with eminent geologists. part of a letter written at this time[ ] gives a valuable insight into the intention of these journeys and the character of the author, who was now in his sixtieth year:-- "i hope to continue for years travelling, making original observations, and, above all, going to school to the younger, but not, for all that, young geologists, whom i meet everywhere, so far ahead of us old stagers that they are familiar with branches of the science, fast rising into importance, which were not thought of when i first began." switzerland, obviously, was visited on this occasion with a very definite purpose. de charpentier, escher von der linth, and other local geologists, had been for some time asserting that the glaciers of the alps, at no remote epoch in geological history, had attained to an enormous size, had buried the swiss lowland and covered it with morainic deposits, and had even welled up high against the flanks of the jura, where the huge blocks of protogine from the mont blanc range--such as pierre à bot and its companion erratics, full feet above the lake of neuchâtel--indicated one position of its terminal moraine. formerly, in common with many other geologists, sir charles had supposed these blocks to have been transported from the alpine peaks by ice-rafts on the sea, at a time when the whole region stood at a considerably lower level. but now, after examining the erratics, their regular and significant distribution, the other glacial débris, the ice-worn surfaces of rock beneath it, and ascertaining the distinctly terrestrial character of the deposits all about the mountains, he unreservedly admitted land-ice to be the only possible agent, and, in accepting this hypothesis, perceived clearly that he must not shrink from applying it to scotland. then he plunged into the mountains to examine and follow the track of the retreating ice-sheet up to the glaciers which are still at work among the higher peaks, passing up the valley of the reuss, crossing the furka pass, and descending the rhone valley to visp, but turning aside to examine the earth pillars on the flank of the eggishorn.[ ] another, and a larger group of these pillars--instances of the erosive action of rain-water on morainic material--was seen near stalden, in the visp-thal; but these had been damaged by the earthquake which two years before had severely shaken this part of the alps. at zermatt the characteristics of glaciers and the effects of ice were carefully studied among the grandest of alpine scenery; then, on returning to the rhone valley, they crossed the alps by the simplon and went on to turin. here he took the opportunity of visiting the huge moraine near ivrea, which rises from the lowland like a range of hills, and of investigating the erratics of the superga, satisfying himself that they really belonged to the miocene deposits of that hill, and were indicative of the existence of glaciers in the alps of that epoch, which had been large enough to reach the sea-level, and to send off masses of ice laden with boulders. then they went on to genoa, and along the beautiful riviera di levante to pisa; thence, after a short visit to florence, proceeding direct from leghorn to naples. here, he once more examined vesuvius, and had the luck to see lava streams actually in motion--"some going fast, others going very slow"--a sight which "gave him many new ideas." a study also of the dykes of somma convinced him that they afforded no support to de beaumont's idea of a distension of the mass.[ ] from naples he went to sicily, in order to make a second examination of etna, and then, after rejoining lady lyell, spent some time in the neighbourhood of rome, visiting the old volcanic district of the alban hills, and making excursions, as they travelled northward, into the apennines. they returned through france, reaching london towards the end of december. but, for a worker so thorough in his methods, this visit to the volcanoes was not enough, so next year, after spending the earlier part of the summer with his brother's[ ] family in the neighbourhood of darmstadt, he left lady lyell there, and set off towards the end of august for a third examination both of vesuvius and of etna. travelling rapidly up the valley of the rhine, he went by geneva to culoz, and over mont cenis to turin and genoa, without halting for geological work, and thence by sea to naples. lava was still flowing from vesuvius, that black mass, with its strange rope-like folds and slaggy wrinkles,[ ] now so well known to every visitor. accompanied by professor guiscardi--one of the most genial and helpful of leaders--sir charles made his way to a vent at the base of the principal cone, where the lava was still welling forth from "a small grotto, looking as fluid as water where it first issued, and moving at a pace which you would call rapid in a river. white-hot, at first, in a canal four or five feet broad, then red before it had got on a yard, then in a few feet beginning to be covered by a dark scum, which thickened fast and was carried along on the surface." but the great question, whether a volcano was mainly a "crater of elevation" or a "crater of ejection," was ever present to his mind; so, in addition to studying the grand sections displayed in the crags of monte somma, he devoted two days to the exploration of the ravines which furrow its outer slopes. he also found time to have another look at the temple of serapis, and to examine the solfatara, which is a striking example of a crater at once broad and low. after a week's halt at naples, sir charles resumed his journey to sicily, landing at messina on september th. by the th he was once more on the slopes of etna, and had begun a twelve-day period of hard work on the mountain, passing five nights in very rough quarters at the casa degli inglesi, , feet above sea-level. during this stay he ascended the principal cone, carefully examining both the larger and the smaller craters, and descended into the val del bove, a laborious expedition, but one which well repaid him by throwing much light on the structure of the volcanic mass. still he was not yet satisfied, for after he had descended to zafarana, he returned to spend another night at the casa degli inglesi in order to satisfy himself about one or two details. from zafarana also he went again to the val del bove, checking and increasing his notes, and devoted another day to a most interesting excursion through picturesque scenery as far as the watershed between this vast hollow in the mountain side and the neighbouring val di tripodo. on all these excursions sir charles, as far as possible, rode, remarking to his wife, "i feel here that a good mule is like presenting an old geologist with a young pair of legs." work on the mountain ended, he spent a little time in examining the tertiary beds of the neighbouring lowland, and then, getting back to messina about the middle of october, returned in due course to england. these two journeys in succession greatly augmented his knowledge of the structure of volcanic cones, and enabled him to deal the death-blow to the "crater of elevation" hypothesis which had found such favour among continental geologists. he could now prove that lava would solidify in a compact form on slopes of thirty-five or even forty degrees--a fact which had been stoutly denied by advocates of that hypothesis, and was able to offer an explanation of the singular structure of the val del bove, viz. that it was a huge gulf, formed by a series of mighty explosions, similar to those which shattered half of the old crater of vesuvius,[ ] and sent one side of bandai san[ ] flying through the air. he returned to england satisfied that his feet were on firm ground, if such a phrase be permissible in regard to a volcano, and that the results[ ] of this conscientious labour in the fulness of his age had strengthened him in the position which he had adopted in his scientific youth. in the next year ( ) lyell also travelled, though the journeys were not so lengthy as their two predecessors. still, in the spring he visited both holland and le puy in auvergne, and in the earlier part of the autumn attended the meeting of the british association at aberdeen, under the presidency of prince albert. a strong body of geologists were present, and lyell was for the fourth time in the chair of the geological section, the prince coming to hear his address. among the old friends whom he met was one who would have been a suitable husband for the famous countess of desmond, for lyell writes of him to mrs. horner, his wife's mother, "dr. f. at ninety-four looks well enough, but having eaten turtle-soup, and melon too close to the rind, and other imprudences, is not quite well to-day!" _o dura doctorum ilia!_ the meeting ended, lyell with some geological friends went off to elgin to examine the sandstone quarried at cutties hillock, near that town. the rock closely resembles the ordinary old red sandstone; it seemed at first sight to form a continuous mass, yet in one place it contained a fossil fish belonging to that period, and in another the remains of a reptile (_telerpeton_). after some days of careful study, the rev. w. s. symonds, who was one of the party, came to the conclusion (which has been fully ratified by later investigations) that the deposits were of different ages; the one with the fish being truly "old red," the other, with the reptile, "new red." the chief cause of the puzzle is that the sand which has been derived from the older rock has gone to form the newer one, and that the usual indications of a discontinuity are practically absent. it affords a valuable caution, for it shows that nature sometimes does set traps, which might well catch even the most wary geologist. in the same autumn lyell read darwin's great work on "the origin of species," by which his scientific position was finally determined, for his letters show that, if any objection to the leading principles in his friend's views had still lingered in his mind, they were overcome by the perusal of this masterly specimen "of close reasoning and long sustained argument." footnotes: [ ] in reference to an essay written by him on the connection between the fauna and flora of the british isles and geological changes. ("memoirs of the geological survey," i. p. .) [ ] life, letters, and journals, vol ii. p. . [ ] he died november th, . [ ] he had the advantage of the company of mr. c. hartung, who was an excellent naturalist and well acquainted with the island. [ ] "elements of geology" (sixth edition), pp. - . [ ] "on the geology of some parts of madeira" (quart. jour. geol. soc., x. p. ). [ ] in a letter to mr. bunbury, dated november th, (life, letters, and journals, vol. ii. p. ). it is written from , harley street, one in the previous august bearing the superscription of , harley street, so that he appears (though there is no allusion to this in his published letters or journals) to have removed into another house in the same street. the number of this was subsequently altered. [ ] another letter to mr. bunbury, dated april th, (_ibid._, p. ). [ ] this deposit belongs to the tertiary era (oligocene system). [ ] life, letters, and journals, ii. p. . [ ] the largest, called the zwerglithurn, is about one and a half hours walk above viesch. [ ] this had been asserted in support of the hypothesis of "craters of elevation." [ ] colonel lyell had retired from the army and returned to england a short time before the outbreak of the indian mutiny. [ ] _see_ professor j. w. judd: "volcanoes" (international scientific series), fig. . [ ] in the famous eruption of a.d. . [ ] a volcano of japan. [ ] these results are worked into the tenth edition of the "principles" (chaps. xxv. and xxvi.). _see also_ a paper on stony lava on steep slopes of etna (proc. roy. soc. , ix. p. ). he received the copley medal from the royal society in november. chapter x. the antiquity of man. though many men on reaching their sixty-third year are content to rest upon their oars and not to attempt new ventures, lyell had plunged into a question which was arousing almost as much excitement as the origin of species--namely, the antiquity of man. it was a question, indeed, which for a long time must have been before his mind--witness his remarks on dr. schmerling's work in the caves near liége; but it had assumed a special significance owing to the famous discovery of flint implements in the valley of the somme.[ ] the whole subject also would have a special interest for lyell, because he had made tertiary deposits his special field in stratigraphy, and had worked at this subject downwards, comparing extinct with living forms, so that he had seen more than others of the borderland which blends by an insensible transition the province of the geologist with that of the archæologist. probably also the thought which he had been giving to the question of the origin of species would bring into no less vivid prominence that of the age and origin of the human race. be this as it may, he undertook a task comparatively novel, and for the next three years was fully occupied in the preparation of his third great book, "the antiquity of man." travel was necessary for this purpose also; but as the journeys were less lengthy than those already described, and led him for the most part over old ground, it is needless to enter into details. he visited the gravels of the somme valley and the caves on the meuse, besides other parts of northern france and belgium,[ ] the gravel pits near bedford, and various localities in england, examining into the evidence for himself, and paying particular attention, not only to the question of man's antiquity, but also to the supposed return of a warmer climate than now prevails after the era of glacial cold. the book was published early in . naturally its conclusions were startling to many and were vigourously denounced by some; but it was a great success, for it ran through three editions in the course of the year. a fourth and enlarged edition was published in . the book may seem, from the literary critic's point of view, rather composite in character, and this objection was made in a good-natured form by a writer in the _saturday review_,[ ] who called it "a trilogy on the antiquity of man, ice, and darwin." that, however, is but a slight blemish, if blemish it be, and it was readily pardoned, because of the general interest of the book, the clearness of its style, and the lucidity of its reasoning. in accordance with his usual plan of work--proceeding tentatively from the known to the unknown--lyell begins with times nearest to the present era and facts of which the interpretation is least open to dispute. he conducts his reader at the outset to the peat mosses of denmark, where weapons of iron, bronze, and stone lie in a kind of stratified order; and to those mounds of shells, the refuse heaps of a rude people, which are found on the baltic shore. next he places him on the site of the pile-built villages which once fringed the shores of swiss and italian lakes. here weapons of iron, of bronze, and of stone are hidden in peat or scattered on the lake-bed. but these log-built settlements, such as those which herodotus described at lake prasias in roumelia, are not the only remnants of an almost prehistoric people, for nearer home we find analogous constructions in the crannoges of ireland--islets partly artificial, built of timber and stone. lyell then passes on from europe to the valleys of the nile and mississippi, and so to the "carses" of scotland. in the last case canoes buried in the alluvial deposits, as in the lowland by the clyde, indicate that some physical changes, slight though they may be, have occurred since the coming of man. but none of these researches lead us back into a very remote past; they keep us still lingering, as it were, on the threshold of history. the weapons which have been described, even if made of stone, exhibit a considerable amount of mechanical skill, for many of them are fashioned and polished with much care, while they are associated with the remains of creatures which are still living at no great distance, if not in the immediate vicinity. accordingly he conducts his reader, in the next place, to the localities where ruder weapons only have been found, fashioned by chipping, and never polished--namely, to the caves of belgium and of britain, of central and of southern france, and to the gravel beds in the valleys of the somme and the seine, of the ouse and other rivers of eastern and southern england. these furnish abundant evidence that man was contemporary with several extinct animals, such as the mammoth and the woolly rhinoceros, or with others which now inhabit only arctic regions, such as the reindeer and the musksheep, and that the valleys since then have been deepened and altered in contour. this evidence, stratigraphical as well as palæontological, proves that important changes have occurred since man first appeared, not only in climate, but also in physical geography. the glacial epoch is the subject of the second part of the book. its pages contain an admirable sketch of the deposits assigned to that age in eastern england, scandinavia, the alps, and north america, with special descriptions of the loess of northern europe, the drifts of the danish island of möen, so like those near cromer, and the parallel roads of glenroy, which lyell now supposes to have been formed in a manner similar to that of the little terrace by the märjalen see. the third part deals with "the origin of species as bearing on man's place in nature." it is a recantation of the views which he had formerly maintained. in all his earlier writings, including the ninth edition of the "principles," he had expressed himself dissatisfied with the hypothesis of the transmutation of species, and had accepted, though cautiously and not without allowing for considerable power of variation, that of specific centres of creation. now, after a full review of the question, he gives his reasons for abandoning his earlier opinions and adopting in the main those advocated by darwin and wallace. nevertheless, through frankly avowing his change of view, he advances cautiously and tentatively, like a man over treacherous ice--so cautiously, indeed, that darwin is not wholly satisfied with his convert, and chides him good-humouredly for his slow progress and over-much hesitation. but this very hesitation was as real as the conversion: the one was the outcome of lyell's thoroughly judicial habit of mind, the other was a proof, perhaps the strongest that could be given, of that mind's freshness, vigour, and candour. the book ends with a chapter on "man's place in nature." on this burning question the author speaks with great caution, but comes to the conclusion that man, so far as his bodily frame is concerned, cannot claim exception from the law which governs the rest of the animal kingdom and he ends[ ] with a few words on the theological aspect of the question: "it may be said that, so far from having a materialistic tendency, the supposed introduction into the earth, at successive geological periods, of life--sensation--instinct--the intelligence of the higher mammalia bordering on reason--and, lastly, the improvable reason of man himself, presents us with a picture of the ever-increasing dominion of mind over matter." footnotes: [ ] found by m. boucher de perthes, who had published a book on the subject in , and had announced the discovery about seven years earlier; but geologists, for various reasons, were not fully satisfied on the matter till the visit of messrs. prestwich and john evans (now sir) in . [ ] he went to florence in , but how far this was for geological work is not stated. [ ] vol. xv. p. . [ ] "antiquity of man," chap. xxiv. chapter xi. the evening of life. the second and third editions of the "antiquity of man" were not mere reprints, since new materials were constantly coming in and researches were continued; for during the summer of sir charles was rambling about wales, visiting the caves of gower in pembrokeshire, and of cefn in denbighshire, the peats of anglesea, and the boulder clay and shell-bearing sands near the top of moel tryfaen. he also went over to paris, apparently about this time, to inquire into the authenticity of specimens--bones with notches upon them--which were supposed to prove man contemporaneous with the cromer forest beds of england, and therefore pre-glacial. shorter journeys were to osborne (by royal command), to suffolk, and to kent. while engaged on the above-named book, he had persistently refused more than one position of honour--such as a trusteeship at the british museum, to be a candidate for the representation of the university of london in parliament, even an honorary degree from the university of edinburgh because he was too busy to undertake the journey. in , also, he seems to have received a warning that he was beginning to grow old, for he became rather seriously unwell, and was ordered to kissingen in bavaria to take a course of the waters. but during the same period two acceptable honours were received--namely, the corresponding membership of the institute of france, in , and an order of scientific merit from the king of prussia in the following year. the years, as must be the case when life's evening shadows are lengthening, begin to be more definitely chequered with losses and with rewards. in his letters, references to the death of friends become frequent. in mrs. horner, lady lyell's mother, died, and in her father, leonard horner, with whom, even for some years before becoming his son-in-law, lyell had been in constant friendly correspondence, passed away in his eightieth year. in the same year lyell was raised to the rank of baronet, and also occupied the presidential chair at the meeting of the british association at bath. his address deals principally with two topics--one local, thermal springs, especially those of bath; the other general, the glacial epoch and its relation to the antiquity of man. he refers, however, in the concluding paragraph to the marked change which, within his memory, opinion had undergone, in regard to catastrophic changes and the origin of species, and to the discovery of the supposed fossil _eozoon canadense_ in the crystalline laurentian rocks of canada. this singular structure appeared to him--as it did to sir w. logan, who had brought specimens for exhibition at the meeting--to be a fossil organism,[ ] and thus to indicate the existence of living creatures at a much earlier period than hitherto had been supposed. but in stating this opinion he checks himself characteristically with these words: "i will not venture on speculations respecting 'the signs of a beginning,' or 'the prospects of an end' of our terrestrial system--that wide ocean of scientific conjecture on which so many theorists before my time have suffered shipwreck." the address contains more than one passage that is well worth quotation, but the following has so wide a bearing, and is so significant as to the effects of early influences, that it should not be forgotten:-- "when speculations on the long series of events which occurred in the glacial and post-glacial periods are indulged in, the imagination is apt to take alarm at the immensity of the time required to interpret the monuments of these ages, all referable to the era of existing species. in order to abridge the number of centuries which would otherwise be indispensable, a disposition is shown by many to magnify the rate of change in prehistoric times, by investing the causes which have modified the animate and inanimate world with extraordinary and excessive energy. it is related of a great irish orator of our day, that when he was about to contribute somewhat parsimoniously towards a public charity, he was persuaded by a friend to make a more liberal donation. in doing so, he apologised for his first apparent want of generosity by saying that his early life had been a constant struggle with scanty means, and that 'they who are born to affluence cannot easily imagine how long a time it takes to get the chill of poverty out of one's bones.' in like manner, we of the living generation, when called upon to make grants of thousands of centuries in order to explain the events of what is called the modern period, shrink naturally at first from making what seems to be so lavish an expenditure of past time. throughout our early education we have been accustomed to such strict economy in all that relates to the chronology of the earth and its inhabitants in remote ages, so fettered have we been by old traditional beliefs, that even when our reason is convinced and we are persuaded that we ought to make more liberal grants of time to the geologist, we feel how hard it is to get the chill of poverty out of our bones."[ ] a presidential address to the british association is no light task; but, in addition to this, lyell was now engaged upon a new edition of the "elements (or manual) of geology," which for some time had been urgently demanded; the last edition also of the "principles"--though , copies had been printed--was practically exhausted. the former work was cleared off before the end of the year, the book appearing in january, , and the latter was at once taken vigorously in hand, as we see from a letter questioning sir john herschel about the earth-pillars on the rittnerhorn, near botzen, and on the influence which changes in the shape of the earth's orbit and the position of its axis would have upon climate--a view which had been advocated by dr. croll. lyell, it will be remembered, had originally regarded geographical conditions as the only factors which modified climate, but he was evidently impressed by croll's argument, and ready, if his mathematics were correct, to admit astronomical changes as an independent, though probably less potent, cause of variation. the christmas of and the following new year were spent in berlin, and in the summer of he had again recourse to kissingen. though he writes that the waters "did him neither harm nor good," he was at any rate well enough after the "cure" to undertake a rather lengthy tour with lady lyell and his nephew[ ] leonard, in the course of which he examined for himself the wonderful earth-pillars near botzen, and visited the märjalen see, that pretty lake held up by the ice of the great aletsch glacier, in order to see whether it threw any light on the origin of the parallel roads of glenroy. he was satisfied that it did, for he found there a large terrace "exactly on a level with the col which separates the valley" occupied by the lake from that of the viesch glacier. on his return to england, he writes a long letter to sir john herschel, discussing the origin of these earth-pillars, and making inquiries as to the precise points from which his friend, more than forty years before, had made some elaborate drawings. the expedition, as well as the letter, to quote lyell's own words, were pretty well for a man who was "battling with sixty-eight years." he complains, however, of little more than occasional attacks of lumbago, and a necessity for taking great care of himself; but his eyes were now more troublesome than they had been, and for the last year he had been driven to avail himself of the services of a secretary,[ ] with the result that he seemed to have acquired a new lease of his eyes, and to be able, for ordinary purposes, to use them almost as well as formerly. after his return from the continent sir charles was working hard at the new edition of the "principles," which obviously gave him much trouble, for letters still remain which were written to herschel on questions relating to climate and astronomy; to hooker, wallace, and darwin on the transmutation of species, the distribution and migration of plants and animals, the effects of geographical changes, and even on such matters as the triassic reptilia of elgin and warwickshire, central india and the cape. at last the first volume of the new and much-enlarged edition (tenth) was published in november, , the second volume not appearing till . few men at that time of life could have accomplished such a piece of work, especially if they had been compelled, as lyell was, to read with the eyes and write with the hands of others. but even now, in regard to field work, he was still able to see things for himself, and, though less vigorous than formerly, to undertake journeys of moderate length. in , in company with his nephew leonard, he examined the glacial and late tertiary deposits of the suffolk coasts; looked once more at the sections of jurassic rocks in the isle of portland and the neighbourhood of weymouth, and doubtless speculated on the origin of the chesil bank and of the fleet. one honour fell to him in this year, which, doubtless, only the accident of his long service on the council had previously kept from him--namely, the wollaston medal of the geological society. in he was strong enough to visit the paris exhibition, after which he went to forfarshire, and attended the meeting of the british association at dundee. in the following year he was present at the same gathering in norwich, besides making various shorter journeys in england and spending september in pembrokeshire with lady lyell and his brother's family,[ ] in whose company evidently he took much pleasure. in the spring of he was again in the field, examining the splendid plant remains of eocene age in the neighbourhood of bournemouth and poole, and the shallow-water deposits of the purbeck group ripple-marked and sun-cracked, together with the traces of their ancient forests. over these he became as enthusiastic as any young geologist. at this time also, apparently, he visited the blackmore museum[ ] at salisbury, and himself found reindeer antlers in the neighbouring gravels at fisherton. in the autumn they again stayed at tenby with colonel lyell's family, when one of the latter was attacked by a serious illness. but sir charles was able to take his nephew leonard to st. david's, and examine the magnificent sections of fossiliferous cambrian rocks, under the guidance of dr. h. hicks, whose name is inseparably connected with the geology of this district. comparatively few records are preserved of the last six years of his life; still they are enough to show that his interest in science never flagged. the few letters which have been printed show no signs of declining mental strength. though his bodily powers had become less vigorous, though his sight was weak, and his limbs were less firm than in the olden times, he was by no means ready to be laid altogether on the shelf. for instance, in the spring of he went back to the coast of suffolk and norfolk, to resume work which he had been unable to complete on his last visit. starting at aldborough, where pliocene deposits are still exposed, from the coralline crag up to the chillesford group, they examined the coasts by southwold and kessingland to lowestoft, seeing "a continuous section, for miles unbroken, of the deposits from the upper part of the pliocene to the glacial drift." the kessingland cliffs afforded good sections of the "forest bed," the deposit which on former occasions he had studied in the neighbourhood of cromer. it was covered by several yards of stratified sand, and that by glacial drift, "with the usual 'boulders' of chalk, flint, lias, sandstone, and other sedimentaries, with crystalline rocks from more distant places." passing on into norfolk, they followed this "forest bed" and the overlying boulder clay, and they found in the latter, near happisburgh, some fragments of sea-shells, and one perfect valve of _tellina solidula_ in a band of gravel, "like a fragment of an old sea-beach," intercalated in the glacial clay. as the origin of this clay has been, of late years, a subject of dispute, it may be interesting to quote sir charles's conclusion:--"i suppose, therefore, we must set it down as a marine formation; and underneath it, from happisburgh to cromer, comes the famous lignite bed and submarine forest, which must have sunk down to allow of the unquestionable glacial formation being everywhere superimposed."[ ] on revisiting sherringham (a village about five miles along the coast to the west of cromer), he found a striking instance of that "sea change" to which in his early days he had called attention. "leonard and i" (he writes to sir c. bunbury) "have just returned from sherringham, where i found that the splendid old hythe pinnacle of chalk, in which the flints were vertical, between seventy and eighty feet high, the grandest erratic in the world, of which i gave a figure in the first edition of my "principles," has totally disappeared. the sea has advanced on the lofty cliff so much in the last ten years, that it may well have carried away the whole pinnacle in the thirty years which have elapsed since our first visit." another letter, bearing date in the next month, to darwin shows that in his seventy-second year his mind was fresh and keen as ever. it discusses an article written by wallace in the _quarterly review_, and indicates the difference in regard to natural selection between lyell's own standpoint and that of his correspondent. the following extract may serve to show the general tenor of the remarks:--"as i feel that progressive development in evolution cannot be entirely explained by natural selection, i rather hail wallace's suggestion that there may be a supreme will and power, which may not abdicate its functions of interference, but may guide the forces and laws of nature." in another passage he refers, to a controversy which had been recently started by professor (afterwards sir a.) ramsay, and over which geologists have been fighting ever since--viz. whether lake-basins are excavated by glaciers. the passage is worth quoting, for it puts the issue in a form which after a quarter of a century is virtually unchanged:-- "as to the scooping out of lake-basins by glaciers, i have had a long, amicable, but controversial correspondence with wallace on that subject, and i cannot get over (as, indeed, i have admitted in print) an intimate connection between the number of lakes of modern date and the glaciation of the regions containing them. but as we do not know how ice can scoop out lago maggiore to a depth of , feet, of which all but is below the level of the sea, getting rid of the rock supposed to be worn away as if it was salt that had melted, i feel that it is a dangerous causation to admit in explanation of every cavity which we have to account for, including lake superior. they who use it seem to have it always at hand, like the 'diluvial wave or the wave of translation,' or the 'convulsion of nature or catastrophe' of the old paroxysmists."[ ] in the summer he took a longer tour, going first to westmoreland and then to forfarshire; after which, in company with lady lyell and his nephew, he went to see the old rocks of ross-shire, above inchnadamff and ullapool, and, as he returned, once more visited the parallel roads of glenroy. but, in the meantime, notwithstanding the difficulties mentioned above, he still kept working at his books. he was now engaged in modifying the "elements of geology." of this, to quote the preface afterwards published, he had published "six editions between the years and , beginning with a small duodecimo volume, which increased with each successive edition, as new facts accumulated, until in it had become a large and somewhat expensive work." he therefore determined, in accordance with the advice of friends, "to bring the book back again to a size more nearly approaching the original, so that it might be within the reach of the ordinary student." this was done by the omission of certain theoretical discussions and all such references to continental geology as were not absolutely necessary.[ ] in sir charles continued to travel, though within the limits of these islands, for he made one journey along the coast of north devon, and a second one to scotland, in the course of which he visited the isle of arran, and on his return halted first at ambleside and then at liverpool, to attend the meeting of the british association, which began on the th of september. the following year he paid an april visit to tintagel, the land's end, and other parts of cornwall, and in the summer went to the north of england. writing from penrith to sir c. bunbury, he remarks "that he had much enjoyed his 'tour of inspection,' and had tried to make it a tour of rest, which is difficult." naturally so, for he had been working his way from buxton on the look-out for glacial deposits and studying especially the stratified drifts on the hills east of macclesfield, , feet above the sea. his remarks on these show that he appreciated fully both the significance of the marine fossils which they contain and the theoretical difficulties caused by the absence of such remains in other deposits, whether in derbyshire or the lake district, or in the lowland between this locality and moel tryfaen, seventy-four miles away. the tenth edition of the "principles" had been quickly sold, and sir charles was now employed in the preparation of another one. in this less change was necessary than on the last occasion; still, the rapid increase of knowledge, more especially in regard to the temperature and currents of the sea, obliged him to make considerable alterations in the parts which dealt with these subjects and with questions of climate, so that he recast or rewrote five chapters. it was published in january, ; and in the summer of that year, no doubt in view of a new edition of the "antiquity of man," he went to the south of france, with lady lyell and professor t. m'k. hughes, to examine the aurignac cave. here several human skeletons had been discovered some years before, apparently entombed with the bones of various extinct mammals, such as the cave-bear and lion, the mammoth and woolly rhinoceros--in short, with a fauna characteristic of the palæolithic age. but was this really the date of the interment? some distinguished geologists were of opinion that, though the cave had been then occupied by wild beasts, its floor had been disturbed, and the corpses buried in neolithic times. on this point lyell was unable to obtain conclusive evidence, and was obliged to confine himself to a statement of the facts and arguments on either side of the question.[ ] shortly after the publication of this new edition of the "antiquity of man" in january, , an unexpected and irreparable bereavement darkened the evening of his days. on april th lady lyell, the companion and helpmate of forty years, was taken from him after a few days' illness from an inflammatory cold.[ ] the shock was the more severe because the loss was so unforeseen. lady lyell was twelve years his junior, and had always enjoyed good health[ ]--"youthful and vigorous for her age," as he writes--so that he "never contemplated surviving her, and could hardly believe it when the calamity happened." he bore the blow bravely, consoling himself by reflecting that the separation, at his age--nearly seventy-six--could not be for very long, and, as he writes to professor heer, of zürich, endeavouring, "by daily work at my favourite science, to forget as far as possible the dreadful change which this has made in my existence." lady lyell was a woman of rare excellence. "strength and sweetness were hers, both in no common degree. the daughter of leonard horner, and the niece of francis horner, her own excellent understanding had been carefully trained, and she had that general knowledge and those intellectual tastes which we expect to find in an educated englishwoman; and from her childhood she had breathed the refining air of taste, knowledge, and goodness. her marriage ... gave a scientific turn to her thoughts and studies, and she became to her husband, not merely the truest of friends and the most affectionate and sympathetic of companions, but a very efficient helper. she was frank, generous, and true; her moral instincts were high and pure; she was faithful and firm in friendship; she was fearless in the expression of opinion without being aggressive; and she had that force of character and quiet energy of temperament that gave her the power to do all that she had resolved to do.... she had more than a common share of personal beauty; but had she not been beautiful she would have been lovely, such was the charm of her manners, which were the natural expression of warmth and tenderness of heart, of quick sympathies, and of a tact as delicate as a blind man's touch."[ ] he was not, however, left to bear in solitude the burden of darkening sight and of a desolated home. his eldest sister, miss lyell, came from kinnordy to take care of his house and watch over him in these last years with an affectionate devotion; and in her company and that of professor hughes he even carried out the plan, which had been already in contemplation, of once more going on to the continent and of visiting professor heer, at zürich. he worked on, as well as slowly increasing infirmities allowed, after his return to england, fully occupied in preparing a second edition of the "student's elements" and a new one of the "principles."[ ] in june, , he again visited cambridge, this time to receive the degree of ll.d.--an honour which that university had been strangely slow in conferring upon him.[ ] it was then too evident that his strength was declining, for he became quickly fatigued by any exertion of body or mind; nevertheless, he was able soon afterwards to make once more the journey to forfarshire, and to visit there several of his earlier geological haunts. in some of these little excursions he had as his companion mr. j. w. judd,[ ] with whose recent researches into the ruined volcanoes of tertiary age and the yet earlier stratified rocks in the western isles of scotland sir charles was hardly less interested than he would have been in the days when the "principles" was a new book. three or four letters written about this time have been printed[ ] which show, from their vigour and freshness, that the mind was still keen and bright, though the bodily machinery was becoming outworn. after his return to town he even ventured, on november th, to dine at the geological club,[ ] of which he had been a member from its foundation, on its fiftieth anniversary meeting, and "spoke with a vigour which surprised his friends." the tale, however, is nearly told; the sands of life were running low. "his failing eyesight and other infirmities now began to increase rapidly, and towards the close of the year he became very feeble. but his spirit was ever alive to his old beloved science, and his affectionate interest and thought for those about him never failed. he dined downstairs on christmas day with his brother's family, but shortly after that kept to his room." on february nd, , charles lyell entered into his rest. the end may have been slightly accelerated by two causes--one, the death, from inflammation of the lungs, after a short illness, of his brother,[ ] colonel lyell, who, up to that time, had visited him almost daily; the other, the shock given to his enfeebled system by accidentally falling on the stairs a few weeks before. but in no case could it have been long delayed; the bodily frame was outworn; the hour of rest had come. his fellow-workers in science felt unanimously that but one place of sepulture was worthy to receive the body of charles lyell--the abbey of westminster, our national valhalla. a memorial, bearing many important signatures, was at once presented to dean stanley, who gave a willing consent, and the interment took place with all due solemnity on saturday the th. the grave was dug in the north aisle of the nave, near that of woodward, one of the pioneers of british geology and the founder of the chair of that science in the university of cambridge. it is marked[ ] by a slab of derbyshire marble, which bears this inscription:-- charles lyell, baronet, f.r.s., author of "the principles of geology." born at kinnordy, in forfarshire, november , ; died in london, february , . throughout a long and laborious life he sought the means of deciphering the fragmentary records of the earth's history in the patient investigation of the present order of nature, enlarging the boundaries of knowledge and leaving on scientific thought an enduring influence. "o lord, how great are thy works, and thy thoughts are very deep. psalm xcii. . sir charles, by his will, left to the geological society of london the die, executed by mr. leonard wyon, of a medal to be cast in bronze, and awarded annually to some geologist of distinction, whether british or foreign. he further left a sum of two thousand pounds, free of legacy duty, to the society, in trust, the interest of it to be applied as follows:--not less than one-third of it to accompany the medal, and the remainder to be given, in one or more portions, for the furtherance of the science. sir charles was succeeded in the family estates by his nephew leonard, the eldest son of colonel lyell, who lives at kinnordy, but has rebuilt the house. he was created a baronet in . footnotes: [ ] the nature of _eozoon_, whether it be the remains of a foraminifer of unusual size and peculiar habit of growth, or merely a very exceptional arrangement of its constituent minerals, has been since the above-named date a fruitful subject of controversy. for some years the balance of opinion was in favour of an organic origin; now it seems to be distinctly tending in the other direction. [ ] report of brit. assoc., , p. xxiv. [ ] colonel lyell's eldest son, the present baronet. [ ] he was fortunate in obtaining the help of miss arabella buckley, a lady of congenial tastes in literature and science. [ ] the relationship was unusually close, for colonel lyell had married another miss horner. [ ] for a description of this fine collection of prehistoric antiquities, _see_ "flint chips," by e. t. stevens, . [ ] life, letters, and journals, ii. p. . [ ] life, letters, and journals, ii. p. . [ ] the book, thus abbreviated, and entitled "the student's elements of geology," was published in . a second edition appeared in february, ; a third, revised by mr. leonard lyell and others, in ; and a fourth, edited by prof. p. m. duncan, in . [ ] "antiquity of man" (fourth edition), chap. vii. [ ] she had been suffering from influenza, but had accompanied her husband and nephews to ludlow at the beginning of the month. they became uneasy at her increasing debility, and returned to town on the th ("life, letters, and journal of sir c. bunbury," iii. p. ). [ ] he mentions, on january th, , that she had not been well enough to breakfast with him, "for the second time only since our marriage." [ ] quoted from an obituary notice by g. s. hillard, esq., in the boston (u.s.) _daily advertiser_ (printed in life, letters, and journals, ii. p. ). [ ] this was published after his death. he had completed one volume; the other was revised by his nephew leonard. [ ] about the same time he was admitted to the freedom of the turners' company in the city of london. [ ] now professor judd, f.r.s., of the royal college of science, south kensington. [ ] life, letters, and journals, ii. pp. - . [ ] the club consists of a certain number of fellows of the geological society, who dine together before the evening meetings. [ ] his brother thomas, who had retired from the navy with the rank of captain, had died (unmarried) some years before at the jointure house (shiel hill), kinnordy, where he had resided with one of his sisters. [ ] a marble bust, a copy by theed of the original executed by gibson, is placed near the grave. chapter xii. summary. in stature, sir charles lyell[ ] was rather above the middle height, somewhat squarely built, though not at all stout, with clear-cut, intellectual features, and a forehead, broad, high, and massive. he would have been a man of commanding presence, if his extremely short sight had not obliged him to stoop and peer into anything he wished to observe. this defect, in addition to the weakness of his eyes was a serious impediment in field work. as professor ramsay remarked in , after spending a few days with him in the south of england, he required people to point things out to him, and would have been unable to make a geological map, "but understood all when explained, and speculated thereon well."[ ] this defect of sight, according to sir j. w. dawson, who had been his companion in more than one excursion in canada, was at times even a source of danger. the expression of his face was one of thoughtful power and gracious benignity.[ ] "in his work, lyell was very methodical, beginning and ending at fixed hours. accustomed to make use of the help of others on account of his weak sight, he was singularly unconscious of outward bodily movement, though highly sensitive to pain. when dictating, he was often restless, moving from his chair to his sofa, pacing the room, or sometimes flinging himself full length on two chairs, tracing patterns on the floor, as some thoughtful or eloquent passage flowed from his lips. but though a rapid writer and dictator, he was sensitively conscientious in the correction of his manuscript, partly from a strong sense of the duty of accuracy, partly from a desire to save his publisher the expense of proof corrections. hence passages once finished were rarely altered, even after many years, unless new facts arose." the characteristic with which anyone who spent some time in charles lyell's company was most impressed, was his thirst for knowledge, combined with a singular openness, and perfect fairness of mind. he was absolutely free from all petty pride, and from "that common failing of men of science, which causes them to cling with such tenacity to opinions once formed, even in the face of the strongest evidence."[ ] ramsay wrote of him,[ ] "we all like lyell much; he is anxious for instruction, and so far from affecting the bigwig, he is not afraid to learn anything from anyone.[ ] the notes he takes are amazing." no man could have given a stronger proof of candour and plasticity of mind and of his care for truth alone than lyell did in dealing with the question of the origin of species. from the first he approached it without prejudice. so long as the facts adduced by lamarck and others appeared to him insufficient to support their hypotheses, he gave the preference to some modification of the ordinarily accepted view--that a species began in a creative act--but after reading darwin's classic work,[ ] and discussing the subject in private, not only with its author, but also with sir j. hooker and professor huxley, he was convinced that darwin was right in his main contention, though he held back in regard to certain minor points, for which he thought the evidence as yet insufficient. of his conduct in this matter, darwin justly wrote: "considering his age, his former views, and position in society, i think his action has been heroic."[ ] dean stanley, in the pulpit of westminster abbey, on the sunday following the funeral, summed up in a few eloquent sentences the great moral lesson of lyell's life. "from early youth to extreme old age it was to him a solemn religious duty to be incessantly learning, fearlessly correcting his own mistakes, always ready to receive and reproduce from others that which he had not in himself. science and religion for him not only were not divorced, but were one and indivisible."[ ] to ascertain the truth, and to be led by reason not by impulse, that was lyell's great aim. sedgwick once[ ] criticised his work in terms which, in one respect, seem to me curiously mistaken: "lyell ... is an excellent and thoughtful writer, but not, i think, a great field observer ... his mind is essentially deductive not inductive." the former criticism, as has been already admitted, is just, but the latter, _pace tanti viri_, seems to me the reverse of the truth. surely there never was a geologist whose habits and methods were more strictly inductive than lyell's. he would spare no pains, and hardly any expense, to ascertain for himself what the facts were; he abstained from drawing any conclusion until he had accumulated a good store; he compared and marshalled them, and finally adopted the interpretation with which they seemed most accordant. this interpretation, however, would be modified, or even rejected, if new and important facts were discovered. surely this is the method of induction; surely this is the mode of reasoning adopted by darwin and by newton, and even by bacon himself. but sedgwick, great man as he was, almost unrivalled in the field, more brilliant, though less persevering than lyell, was not always quite free from prejudices; and it may be noted that he more than once stigmatises an opinion which he dislikes by declaring it not to be in accordance with inductive methods. sir joseph hooker's judgment was far more accurate: "one of the most philosophical of geologists, and one of the best of men"[ ]; or that of charles darwin himself: "the science of geology is enormously indebted to lyell--more so, as i believe, than to any other man who ever lived."[ ] lyell felt a keen interest in the broader aspect of political questions, and this not only in his own country,[ ] though he took little or no share in party struggles, for the vulgarity of the demagogue and the coarseness of the hustings were offensive to a man of such refinement. his opinions harmonised with his scientific habits of thought, always progressive, but never extravagant. he was in favour of greater freedom in education, of the restriction of class privileges, and of an extension of the franchise, but he saw clearly that anything like universal suffrage, as the world is at present constituted, would only mean giving a preponderating influence to those least competent to wield it; that is, to the more ignorant and easily deluded. as in such cases the glib tongue would become more potent than the voice of reason, the demagogue than the statesman, he feared that the standard of national honour would be almost inevitably lowered, and national disaster be a probable result. that all men are equal and entitled to an equal share in the government--a dogma now regarded in some circles as almost sacred--would have been repudiated by him with the quiet scorn of a man who prefers facts to fancies, and inductive reasoning to sentimental rhapsody. a partisan he could not be, for he saw too clearly that in political matters truth and right were seldom a monopoly of any side, and though by no means wanting in a certain quiet and restrained enthusiasm, he had almost an abhorrence of fanaticism. one example may serve for many, to indicate the way in which he regarded both this spirit and any difficult question. naturally he had a strong dislike to slavery; he fully recognised the injustice and wrong to the negro, and the evil effects upon the master. nevertheless, after visiting the southern states, and giving the impressions of his journey, he thus expresses himself: "the more i reflected on the condition of the slaves, and endeavoured to think on a practical plan for hastening the period of their liberation, the more difficult the subject appeared to me, and the more i felt astonished at the confidence displayed by so many anti-slavery speakers and writers on both sides of the atlantic. the course pursued by these agitators shows that, next to the positively wicked, the class who are usually called 'well-meaning persons' are the most mischievous in society." he then points out how a strong feeling against slavery had been springing up in virginia, kentucky, and maryland; how the emancipation party had been gaining ground, and slavery steadily retreating southwards, but "from the moment that the abolition movement began, and that missionaries were sent to the southern states, a reaction was perceived--the planters took the alarm--laws were passed against education--the condition of the slave was worse, and not a few of the planters, by dint of defending their institutions against the arguments and misrepresentations of their assailants, came actually to delude themselves into a belief that slavery was legitimate, wise, and expedient--a positive good in itself."[ ] at a subsequent period he speaks of mrs. beecher stowe's famous book, "uncle tom's cabin," as "a gross caricature." but in the great struggle between the northern and southern states, his sympathies went with the former. it was the fairness of his criticisms, and his hearty appreciation of the good side in american institutions, that won him many friends and made his books welcome on that side of the atlantic. lyell's views on religious questions accorded, as might be expected, with the general bent of his mind. he was a member of the church of england,[ ] appreciated its services, the charm of music, and the beauty of architecture, but he failed to understand why nonconformity should entail penalties, whether legal or social. his mind was essentially undogmatic; feeling that certainty was impossible in questions where the ordinary means of verification could not be employed, he abstained from speculation and shrank from formulating his ideas, even when he was convinced of their general truth. he was content, however, to believe where he could not prove, and to trust, not faintly, the larger hope. so he worked on in calm confidence that the honest searcher after truth would never go far astray, and that the god of nature and of revelation was one. he sought in this life to follow the way of righteousness, justice, and goodness, and he died in the hope of immortality. as he disapproved of any approach to persecution on the ground of religion, so he objected strongly to the exclusive privileges which in his day were enjoyed by the church of england, especially to its virtual monopoly of education. on this point he several times expresses himself in forcible terms; as, for instance, in these words: "the church of england ascendency is really the power which is oppressive here, and not the monarchy, nor the aristocracy. perhaps i feel it too sensitively as a scientific man, since our puseyites have excluded physical science from oxford. they are wise in their generation. the abject deference to authority advocated conscientiously by them can never survive a sound philosophical education."[ ] to this party--or to the "catholic movement," as it is now often called--in the church of england, lyell had a strong dislike; he deemed their claims to authority unwarrantable, their practices in many respects either childish or superstitious. as we have endeavoured to bring out in the course of this volume the guiding principles of lyell's work, a brief recapitulation only is needed as a conclusion. that work was regulated by two maxims: the one, "go and see"; the other, "prefer reason to authority." to the first maxim he gave expression more than once, while he was always inculcating it by example. imitating the well-known saying of demosthenes in regard to oratory, he emphatically declares that in order to form comprehensive views of the globe, the first, the second, and the third requisite is "travel."[ ] what he preached, he practised; about a quarter of the last fifty years of his life must have so been spent. of the second maxim also he was a living example. it was his practice not only to see for himself, but also to judge for himself, in all questions other than those necessarily reserved for specialists; his rule, that thought should be free from the fear of man, but subject to the laws of reasoning. as a young man he had advocated, almost single-handed, scientific views which were unpopular alike with the older authorities in geology and with the supposed friends of religion; he had protested against the invocation of catastrophic destruction and cataclysmal flood in order to clear away difficulties in the past history of the earth; in other words, against an appeal to miracle, when a cause could be found in the existing order of nature; and he had disputed the right of any priesthood, whether romanist or protestant, to hold the keys of knowledge. he vindicated, against all corners, his claim--nay, his birthright--to sit, as an earnest student, at the feet of nature to listen and to learn, as she chose to teach, whether by the acted drama of the living world or by the silent record of the rocks. he was, in short, more observer than theorist, more philosopher than poet, more a servant of reason than a dreamer of dreams. his example is one well worthy of remembrance at the present epoch. the "whirligig of time" has brought its revenges, and has introduced into geology a class of students almost unknown in the days when lyell was in his vigour. the developments of mineralogy and palæontology, helpful and valuable as they have been by making geology more of an exact science and, in some cases, substituting order for confusion, have tended to produce students very familiar with the apparatus of a laboratory or the collections of a museum, but not with the face of the earth. this, in itself, would not be necessarily hurtful, because the field of geology is so wide that there is room for all; but it leads sometimes to an undue exaltation of trifles, to an over-estimation of the "mint, anise, and cummin" of science, to a waste of time upon what is called the literature of the subject. this last often means either searching much chaff for a few grains of wheat, or spending much labour with the hope of discovering whether a or b was the first to confer a name upon a species; the priority perhaps being only of a few months, and that name neither particularly appropriate nor euphonious. partly from this, partly from other causes, the importance, nay, the absolute necessity of travel, for the education of a geologist is now too often forgotten. in this science there are many questions--some of them almost fundamental--for which no perquisitions in a library, no research in a laboratory, no studies in a museum, however conscientiously patient and painstaking they may be, can be accepted as an adequate preparation; questions in which nature is at once the best book, the best laboratory, and the best museum, and experience is the only safe teacher. what would lyell have said to men--and such might now be named--who undertook to discuss wide geological problems with the most limited experience who, for example, posed as authorities upon what ice can or cannot do, without having even seen a glacier or speculated on the most intricate questions in petrology without having studied more than some corner of this island, or, indeed, without any precise knowledge of that? would not he--averse as he was to speaking severely--have censured them for talking about things which they could not possibly understand, and for darkening counsel by words without knowledge? lyell, no doubt, had exceptionally favourable opportunities. the eldest son of a wealthy man--who contentedly acquiesced in his seeking fame rather than fortune, and supplied him with the necessary funds--his time was his own, as he had not only enough for his ordinary wants, but also could afford to travel as much as he desired. his social position was sufficiently good to facilitate his access to those who had already attained to eminence. he was blessed with a sympathetic and helpful wife, and they had no children. thus they were perfectly free, both in the disposal of their time at home and in their peregrinations abroad. besides these things they both enjoyed good health. lyell's constitution was not, indeed, so robust that he could take liberties; he had to be careful about "cakes and ale," and to lead a fairly regular life,[ ] but by so doing he was able to be always in good condition for his work. his eyes, in fact, were his only trouble and who is there who has not got his own "thorn in the flesh"? lyell also was happy in all his domestic relations. his letters indicate that all the family--on both sides--were on affectionate terms, and contain few references to anxieties and troubles, such as the sickness and death of those dear to him, until his life approached the period when such trials become inevitable. thus free from the impediments which have beset many other men of marked ability, such as weak health and physical suffering, the wearing anxiety of an invalid wife or a sickly family, the harassing cares of pecuniary losses or of an insufficient income, lyell had an exceptional chance. but other men have the same and do not use it; they are crippled by this burden or diverted by that allurement, and "might have been" too often becomes their epitaph. lyell never faltered in the course which, comparatively early in life, he had marked out for himself. with that steady persistency and quiet energy which are characteristic of the lowland scot, he put aside all temptations and everything which threatened to interfere with his work. while neither recluse nor hermit, neither churlish nor unsociable, nay, while thoroughly enjoying witty and intellectual society, he allowed nothing to distract him from his main purpose. convinced that there was a work which he could do, and a name which he could win, he was willing, for sake of this, to run risks and to make sacrifices. he did not indeed despise fame, but he never condescended to unworthy arts to obtain it; he held that the labourer was worthy of his hire, but with him it was always "the work first, and the wage second," whether that were coined gold or laurel wreath. he was singularly free from all petty jealousies, and ready to learn from all who could teach him anything, but he was no weakling, swayed by every breath of wind, for he reached his conclusions slowly and cautiously, and never stopped to ask whether they would be popular. "forward, for truth's sake," that was the motto of his life. in yet another way was lyell _felix opportunitate vitæ_. in his days, geology might be compared to a country which had been for some time discovered but was not yet explored. settlements had been established here and there; in their neighbourhood some ground had been cleared, and a firm base of operations had been secured, but around and beyond was the virgin forest, the untrodden land. at almost every step the traveller met with some fresh accession to his knowledge or a new problem to solve. he could feel the allurement of expectation or the joy of discovery even in countries otherwise well known; where now he can hope only to pick up some tiny detail or to plunge into some interminable controversy. if he now desires "fresh fields and pastures new," he must wander beyond the limits of civilised lands; for within these every crag is hammer-marked, and the official geologist is at work making maps. but not only this, lyell lived in the days when the literature of his science was of very modest dimensions. this had its obvious drawbacks, but it had also its advantages, which, perhaps, were more than compensations. at the present day the conscientious student is in danger of being overwhelmed by the mass of papers, pamphlets and books, from all lands and in all languages--which he is expected, if not to read, at least to scramble through before venturing to write on any subject. fifty years ago it required a very limited amount of study--often only a few hours' research--to put the geologist in possession of all that was known, so that he approached his theme very much as a mathematician attacks a problem. this burden of scientific literature, seeing that life is short and human strength is limited, threatens to stifle the progress of science itself, and we can hardly venture to expect that any more great generalisations will be made in geology or palæontology, unless a man arise who is daring enough to subordinate reading to thinking, and so strong in his grasp of principles that he can make light of details. it has been sometimes said that lyell was not an original thinker. possibly not; _vixere fortes ante agamemnona_ is true in science no less than in national history; there were mathematicians before newton, philosophic naturalists before darwin, geologists before lyell. he did not claim to have discovered the principle of uniformity. he tells us himself what had been done by his predecessors in italy and in scotland: but he scattered the mists of error and illusion, he placed the idea upon a firm and logical basis; in a word, he found uniformitarianism an hypothesis, and he left it a theory. that surely is a more solid gift to science, a better claim to greatness, than any number of brilliant guesses and fancies, which, after coruscating for a brief season to the amazement of a gaping crowd, explode into darkness, and are no more seen. but to a certain extent lyell has thrown his own work into the shade. the fame of his books causes his numerous scientific papers[ ] to be overlooked; particularly his contributions to the history of coalfields and to the classification of the tertiary deposits. moreover, into these books he was constantly incorporating new and original matter. we may be fairly familiar with the "principles" and the "elements," but we fail to realise until we have read his "life" and the accounts of his two tours in america how much those books are made up from the results of actual experience and personal study in the field. it has been also said that lyell carried the principle of "uniformity" a little too far. but, suppose we concede this, does it amount to more than the admission that he was human? it is almost inevitable that the discoverer or prophet of a great truth, who has to encounter the storm and stress of controversy, should state his case a little too strongly, or should overlook some minor limitation. suppose we grant that lyell was a little too lavish in his estimate of the time at the disposal of geologists. the physicist had not then intervened, with arguments drawn from his own science, to insist that neither earth nor sun can reckon their years by myriads of myriads, and even now this controversy cannot be regarded as closed. suppose we grant that in accepting hutton's dictum, "i find in the earth no signs of a beginning," lyell was misled by appearances,[ ] which have since proved to be delusive, and that facts, so far as they go, point rather in the contrary direction. well, this point also is not yet to be regarded as settled; and of one thing, at any rate, we may be sure, that if lyell were now living he would frankly recognise new facts, as soon as they were established, and would not shrink from any modification of his theory which these might demand. great as were his services to geology, this, perhaps, is even greater--for the lesson applies to all sciences and to all seekers after knowledge--that his career, from first to last, was the manifestation of a judicial mind, of a noble spirit, raised far above all party passions and petty considerations, of an intellect great in itself, but greater still in its grand humility; that he was a man to whom truth was as the 'pearl of price,' worthy of the devotion and, if need be, the sacrifice of a life. footnotes: [ ] in this paragraph i have ventured to quote largely, and more or less verbatim, from the words of miss buckley (lyell's secretary) in the article on his life, written by my friend professor g. a. j. cole, in the "dictionary of national biography," vol. xxxiv. [ ] "life of sir a. ramsay," by sir a. geikie, chap. v. [ ] _vidi tantum_, when his powers were beginning to fail, but it is this expression which is stamped on my mind as characteristic of the face in charles lyell, and, i may add, also in charles darwin. [ ] j. w. dawson, cited in the " dictionary of national biography." [ ] _ut suprà._ [ ] i may add my own testimony. when the second edition of the "student's elements" was passing through the press. i ventured to write to him about one or two petrological details, which i thought might be more precise. though at that time i had published but few papers, i received more than one kind letter with the request that i would read some of the proof-sheets of the book and suggest alterations. [ ] "the origin of species," published in . [ ] "life and letters of c. darwin," ii. p. . [ ] quoted in life, letters, and journals, ii. p. . [ ] in . "life and letters of sedgwick," ii. p. . [ ] "life, letters, and journal of sir c. bunbury," iii. p. . [ ] "life and letters of c. darwin," i. p. . [ ] he maintained for many years an interesting correspondence with mr. g. ticknor, of boston, u.s.a., in which he often discusses political questions, both british and american. [ ] "travels in north america," chap. ix. [ ] in the later part of his life he appears to have sympathised more with the "unitarians," for he attended the services at dr. martineau's chapel in little portland street, though i am not aware that he formally seceded from the church of england. [ ] life, letters, and journals, vol. ii. pp. - . it must however, be remembered that the high church party were not alone in their opposition; indeed, after a time, they were more tolerant of geologists than the extreme "evangelical" school. i have some cuttings from the _record_ newspaper, dated about , which are interesting examples of narrow-minded ignorance and theological arrogance. [ ] life, letters, and journal, i. p. . "principles," i. (eleventh edition). [ ] he admits that when lord enniskillen and murchison had seduced him, after a geological society meeting, to partake of pterodactyl (woodcock) pie and drink punch into the small hours, his work suffered for four or five days afterwards. [ ] these were about seventy-six in number, the great majority written prior to the last twenty years of his life. [ ] such as the seeming intercalation of crystalline schists with fossiliferous rocks, or the immediate sequence of the two. index. address to the british association at bath, alps, the, glaciers of, america, first visit to, ----, second visit to, ----, third visit to, ----, fourth visit to, "antiquity of man" published, ----, synopsis of, aurignac cave, the, visit to, auvergne, journey to, avicenna's treatise on minerals, bachelor of arts, degree of, conferred on him, bar, called to the, baronet, created a, beaumont, elie de, his theory of mountain-chains, birth and birthplace, his, brittany, tour in, british association, address to, cave remains, dr. schmerling's collection, continental researches in geology, cromer, investigations at, cuvier, meets with, in paris, darwin and lyell, ----, his opinion of lyell's character, death of lady lyell, ---- sir charles lyell, denmark and southern norway, researches in, deputy-lieutenant of forfar, appointment as, deshayes, the eminent conchologist, diluvialists and fluvialists, the, doctor of laws degree conferred on him, eifel, visit to the volcanic district of, "elements of geology" published, engis skull, the, entomology, early studies in, etna explored, family, the lyell, father, his, fluvialists and diluvialists, the, "forest bed," the, frascatoro, his views on geology, generelli's theories, geological society, elected a fellow of the, ----, his first papers to the, ----, elected secretary of the, ----, elected president of the, geology, first studies in, ----, continental researches, glaciers of the alps, his theory of the, grand canary, voyage to, great dismal swamp, the, explored, horner, miss, marriage with, humboldt, meeting with, in paris, huttonian theory, the, infancy, inscription on lyell's tombstone, ireland, visit to, kessingland cliffs and the "forest bed," king's college, lectures at, knighted, law, the, studies for, lectures at king's college, ---- at the royal institution, leonardo da vinci, his conclusions on geology, letter to herschel on the origin of species, lyell family, the, ----, lady, death of, ----, sir charles, death of, "lyellia," the moss named, madeira, voyage to, marriage to miss horner, his, medal of the royal society presented to him, member of the institute of france, elected, midhurst, school days at, moel tryfaen, crags of, montreal and quebec, journey to, moro's views, moss called "lyellia," mother, his, naples, visit to, narrow escape when a child, new orleans, journey to, niagara falls, his impressions of, normandy and brittany, researches in, north america, travels in, "omar the learned," his "retreat of the sea," order of scientific merit bestowed by the king of prussia, origin of species, letter to herschel on the, oxford, undergraduate days at, palma, investigations at, personal characteristics of lyell, "plastic force" dogma, the, political views, his, president of the geological society, is elected, "principles of geology," first volume published, ----, second volume published, ----, third volume published, ----, its history and various editions, professor of geology at king's college, pyrenees, visit to the, quebec and montreal visited, religious questions, his views on, ringwood, school days at, royal institution, lectures at, royal society, is elected a fellow of the, (note) ----, medal of, presented to him, salisbury, school days at, sarum, excursions to, scandinavia, investigations in, school days, schmerling's collection of cave-remains, scientific papers, large number written by him, scrope's work on "volcanoes," "sea-serpent," lyell's views concerning it, "second visit to north america" published, stanley, dean, his remarks respecting lyell's life-work, switzerland, first tour in, teneriffe, researches at, tombstone, lyell's, inscription on, "travels in north america" published, undergraduate days, vallisneri's conclusions, views on religious questions, lyell's, vinci, leonardo da, his conclusions on geology, wales, visit to, werner's theories, will, lyell's, wollaston medal of the geological society presented to him, . printed by cassell & company, limited, la belle sauvage, london, e.c. +---------------------------------------------+ | transcriber's note: | | | | typographical errors corrected in the text: | | | | page vivarrais changed to vivarais | | page excellenza changed to eccellenza | | page vivarrais changed to vivarais | | page brorgniart changed to brongniart | | page occured changed to occurred | +---------------------------------------------+ the geological story of the isle of wight. [illustration: _photo by j. milman brown, shanklin._] gore cliff--upper greensand with chert beds the geological story of the isle of wight by the rev. j. cecil hughes, b.a. _with illustrations of fossils by maud neal_ london: edward stanford, limited , , & long acre, w.c. . preface no better district could be chosen to begin the study of geology than the isle of wight. the splendid coast sections all round its shores, the variety of strata within so small an area, the great interest of those strata, the white chalk cliffs and the coloured sands, the abundant and interesting fossils to be found in the rocks, awaken in numbers of those who live in the island, or visit its shores, a desire to know something of the story written in the rocks. the isle of wight is classic ground of geology. from the early days of the science it has been made famous by the work of great students of nature, such as mantell, buckland, fitton, sedgwick, owen, edward forbes, and others, who have carried on the study up to the present day. many of the strata are known to geologists everywhere as typical; several bear the names of the island localities, where they occur; some--and those not the least interesting--are not found beyond the limits of the island. though studied for so many years, there is no exhausting their interest: new discoveries are constantly made, and new questions arise for solution. to those who have become interested in the rocks of the island, and the fossils they have found in them, and who wish to learn how to read the story they tell, and to know something of that story, this book is addressed. it is intended to be an introduction to the science of geology, based on the geology of the isle of wight, yet leading on to some glimpse of the history presented to us, when we take a wider outlook still, and try to trace the whole wondrous path of change from the world's beginning to the present day. i wish to express my warmest thanks to miss maud neal for the beautiful drawings of fossils which illustrate the book, and to professor grenville a. j. cole, f.r.s., for his kindness in reading the manuscript, and for valuable suggestions received from him. i have also to acknowledge my indebtedness to mr. h. j. osborne white's new edition of the _memoir of the geological survey of the isle of wight_, ; and to thank mr. j. milman brown, of shanklin, for the three photographs of island scenery, showing features of marked geological interest, and mr. c. e. gilchrist, librarian of the sandown free library, for kindly reading the proofs of the book. j. cecil hughes. mar., . contents chap. page i. the rocks and their story ii. the structure of the island iii. the wealden strata: the land of the iguanodon iv. the lower greensand v. brook and atherfield vi. the gault and upper greensand vii. the chalk viii. the tertiary era: the eocene ix. the oligocene x. before and after: the ice age xi. the story of the island rivers; and how the isle of wight became an island xii. the coming of man xiii. the scenery of the island: conclusion illustrations of fossils _plate i.--facing page ._ wealden cyrena limestone vertebra of iguanodon lower greensand perna mulleti meyeria vectensis (atherfield lobster) panopæa plicata terebratula sella _plate ii.--facing page ._ lower greensand trigonia caudata trigonia dædalea gervillia sublanceolata upper greensand (ammonite) mortoniceras rostratum nautilus radiatus _plate iii.--facing page ._ lower greensand thetironia minor rhynchonella parvirostris upper greensand (pecten) neithea quinquecostata chalk (ammonite) mantelliceras mantelli (sea urchins) micraster cor-anguinum echinocorys scutatus (internal cast in flint) _plate iv.--facing page ._ eocene cardita plarnicosta turritella imbricataria nummulites lævigatus (fusus) leiostoma pyrus oligocene limnæa longiscata planorbis euomphalus cyrena semistriata diagrams facing page . coast, sandown bay . coast, atherfield . coast, whitecliff bay . section through headon hill and high down. (strata seen at alum bay) . st george's down , . development of river systems . the old solent river . shingle at foreland photographs facing page . gore cliff. _frontispiece._ . chalk at the culver cliffs. . chalk at scratchell's bay. geological map of the isle of wight chapter i the rocks and their story walking along the sea shore, with all its varied interest, many must from time to time have had their attention attracted by the shells to be seen, not lying on the sands, or in the pools, but firmly embedded in the solid rock of the cliffs and of the rock ledges which run out on to the shore, and have, it may be, wondered sometimes how they got there. at almost any point of the coast of the isle of wight, in bands of limestone and beds of clay, in cliffs of sandstone or of chalk, we shall have no difficulty in finding numerous shells. but it is not only in the rocks of the sea coast that shells are to be found. in quarries for building stone and in the chalk pits of the downs we see shells in the rock, and may often notice them in the stones of walls and buildings. how did they get there? the sea, we say, must once have been here. it must have flowed over the land at some time. now let us think. we are going to read a wonderful story, written not in books, but in the rocks. and it will be much more valuable if we learn to read it ourselves, than if we are just told what other people have made out. we know a thing much better if we see the answers to questions for ourselves than if we are told the answers, and take some one else's word for it. and if we learn to ask questions of nature, and get answers to them, it will be useful in all sorts of ways all through life. now, look at the shells in the rock of cliff and quarry. how are they there? the sea cannot have just flowed over and left them. the rock could not have been hard, as it is now, when they got in. some of the rocks are sandstone, much like the sand on the sea shore, but they are harder, and their particles are stuck together. does sand on a sea shore ever become hard like rock, so that shells buried in it are found afterwards in hard rock? now we are getting the key to a secret. we are learning the way to read the story of the rocks. how? in this way. look around you. see if anything like this is happening to-day. then you will be able to read the story of what happened long, long ago, of how this world came to be as it is to-day. we have asked a question about the sandstone. what about the clays and the limestone? as before, what is happening to-day? is limestone being made anywhere to-day, and are shells being shut up in it? are shells in the sea being covered up with clay,--with mud,--and more shellfish living on the top of that; and then, are they, too, being covered up? so that in years to come they will be found in layers of clay and stone like those we have been looking at in quarry and sea cliff? we have asked our questions. now we must look around, and see if we can find the answers. after it has been raining heavily for two or three days go down to the marshes of the yar, and stand on one of the bridges over the stream. we have seen it flowing quite clear on some days. now it is yellow or brown with mud. where did the mud come from? go into a ploughed field with a ditch by the side. down the ditch the rain water is pouring from the field away to the stream. it is thick with mud. off the ploughed field little trickles of water are running into the ditch. each brings earth from the field with it. off all the country round the rain is trickling away, carrying earth into the ditches and on into the stream, and the stream is carrying it down into the sea. now think. after every shower of rain earth is carried off the land into the sea. and this goes on all the year round, and year after year. if it goes on long enough--? look a long way ahead, a hundred years,--a thousand,--thousands of years. we shall be talking soon of what takes many thousands of years to do. why, you say, if it goes on long enough, all the land will be carried into the sea. so it will be. so it must be. you see how the world is changing. you will soon see how it has changed already, what wonderful changes there have been. you will see that things have happened in the world which you never guessed till you began to study geology. now, let us go a bit further. what becomes of all the mud the streams and rivers are carrying down into the sea? look at a stream coming steeply down from the hills. how it rushes along, rolling pebbles against one another, sweeping everything before it, clearing out its channel, polishing the rocks, and carrying all it rubs off down towards the sea. now look at a river near its mouth in flat lowland country. it flows now much slower; and so it has not power to bear along all the material it swept down from the hills. and so it drops a great deal; it is always silting up its own channel, and in flood time depositing fresh layers of mud on the flat meadow land,--the alluvial flat,--through which it generally flows in the last part of its course. but a good deal of sediment is carried by the river out to sea. the water of the river, moving slower as it enters the sea, has less and less power to sweep along its burden of sand and mud, and it drops it on the sea bottom,--first the bigger coarser particles like the sand, then the mud; farther out, the finer particles of mud drop to the bottom. during the exploring cruise of the _challenger_, under the direction of sir wyville thomson, in - , the most extensive exploration of the depths of the sea that has been made up to the present time, it was found that everything in the nature of gravel or sand was laid down within a very few miles, only the finer muddy sediments being carried as far as to miles from the land, the very finest of all, under most favourable conditions, rarely extending beyond , and never exceeding miles from land into the deep ocean. so gradually layer after layer of sand and mud cover the sea bed round our coasts; and shells of cockles and periwinkles, of crabs and sea urchins, and other sea creatures that have lived on the bottom of the sea are buried in the growing layers of sand and mud. as layer forms on layer, the lower layers are pressed together, and become more and more solid. and so we have got a good way towards seeing the making of clay and sandstone with shells in them, such as we saw in the sea cliffs and the quarries. but it is not only rain and rivers that are wearing the land away. all round the coasts the sea is doing the same work. we see the waves beating against the shores, washing out the softer material, hollowing caves into the cliffs, eating away by degrees even the hardest rock, leaving for a while at times isolated rocks like the needles to mark the former extension of the land. most people see for themselves the work of the sea, but do not notice so much what the rain and the frost, the streams and the rivers are doing. but these are wearing away the ground over the whole country, while the sea is only eating away at the coast line. so the whole of the land is being worn away, and the sand and mud carried out into the sea, and deposited there, the material of new land beneath the waters. how do these beds rise up again, so that we find them with their sea shells in the quarry? well, we look at the sea heaving up and down with the tides, and we think of the land as firm and fixed. and yet the land also is continually heaving up and down--very slowly,--far too slowly for it to be noticed, but none the less surely. the exact causes of this are not yet well understood, because we know but little about the inside of the earth. the deepest mine goes a very little way. we know that parts of the interior are intensely hot. the temperature in a mine becomes hotter, about °f. for every ft. we go down on the average. we know that there are great quantities of molten rock in places, which, in a volcanic eruption is poured out in sheets of lava over the land. there are great quantities of water turned into steam by the heat, and in an eruption the steam pours out of the crater of the volcano like the clouds of steam out of the funnel of a locomotive. the people who live about a volcano are living, as it were, on the top of the boiler of a steam engine; and their country is sometimes shaken up and down like the lid of a kettle by the escaping steam. in such a country the land is often changing its level. a few miles from naples at pozzuoli, the ancient puteoli, may be seen columns of what appears to be an ancient market hall, though it goes by the name of the temple of serapis. about half way up the columns are holes bored by boring shellfish, such as we may find on the shore here at low tide. we see from this that since the building was constructed in roman times the land has sunk, and carried the columns into the sea, and shellfish have bored into them. then the land has risen, and lifted the columns out of the sea again. but it is not only in the neighbourhood of volcanoes that the land is moving. not suddenly and violently, but slowly and gradually great tracts of land rise and sink. sometimes the land may remain for a long time nearly stationary. the southern coasts of england seem to stand at much the same level as in the time of the romans , or , years ago. on the other hand there is evidence which seems to show that the coast of norway has for some time been gradually rising. it was thought at one time that the interior of the earth was liquid like molten lava, and that the land we see was a comparatively thin crust over this like the crust of a pie. but it is now believed for various mathematical reasons, that the main mass of the earth is rigid as steel. still underneath the surface rocks there must be a quantity of semi-fluid matter, like molten rock, and on this the solid land sways about, as we see the ice on a pond sway with the pressure of the skaters on it. so the solid land, pressed by internal forces, rises and falls like the elastic ice, sometimes sinking and letting the sea flow over, then rising again, and bringing up the land from beneath the sea. again, as the heated interior of the earth gradually cools by the radiation of the earth's heat into space, it will tend to shrink away from the cooler rocks of the crust. this then, sinking in upon the shrinking interior, will be thrown into folds, like the skin on a shrivelled apple. seeing, as we often do, layers of rock thrown into numerous folds, so as to occupy a horizontal space far less than that in which they were originally laid down, we can hardly resist the conclusion that shrinkage of the cooling interior of the earth has been a chief cause of the greatest movements of the surface, and of the lateral pressure we so often find the strata to have undergone. as we study geology we shall find plenty to show that the land does rise and fall, that where now is land the sea has been, that land once stretched where now is sea, though there is still much which is not well understood about the causes of its movements. we have seen how many of the rocks are made in the sea,--the sandstones and the clays,--but there are two other kinds of rocks, about which we must say a little. the first are the igneous rocks, which means rocks made by fire. these rocks have solidified, most frequently in crystalline forms, from a molten mass. lava, which flows hot and fluid, from a volcano, and cooling becomes a sheet of solid rock, is an igneous rock. some igneous rocks solidify under ground under great pressure, and become crystalline rocks such as granite. we shall not find these rocks in the isle of wight. we should find them in cornwall, wales, and scotland; and, if we could go deep enough, we should find some such rock as granite underneath the other rocks all the world over. the other rocks, such as the sandstones and clays, are called sedimentary rocks, because they are formed of sediment, material carried by the sea and rivers, and dropped to the bottom. they are also called stratified rocks, because they are formed of strata, _i.e._, beds or layers, as we see in cliff and quarry. but we have seen another kind of rock,--the limestones. in sandown bay towards the culvers, bands of limestone run through the dark clay cliffs, and broken fragments lie on the shore, looking like pieces of paving stone. examining these we find that they are made up of shells, one band of small oysters, the others of shells of other kinds. you see how they have been made. there has been an oyster bed, and the shells have been pressed together, and somehow stuck together, so that they have formed a layer of rock. they are stuck together in this way. the atmosphere contains a small quantity of carbonic dioxide, and the soil a larger quantity, the result of vegetable decomposition. rain water absorbs some of it, and carries it into the rocks, as it soaks into the ground. this gas has the property of combining with carbonate of lime,--the material of which shells and limestone are made. the bicarbonate of lime so formed is soluble in water, which is not the case with the simple carbonate. water containing carbonic dioxide soaking into a limestone rock or a mass of shells dissolves some of the carbonate of lime, and carries it on with it. when it comes to an open space containing air, some of the carbonic dioxide is given off, leaving the insoluble carbonate of lime again. so by degrees the hollows are filled up, and a solid layer of rock is formed. even while gathering in the sea the shell-fragments may be cemented by the deposit of carbonate of lime from sea-water containing more of the soluble bicarbonate than it can hold. these limestones are examples of rocks which are said to be of organic origin, that is to say, they are formed by living things. organic rocks may be formed by animal or vegetable growth. rocks of vegetable origin are seen in the coals. a peat bog is composed of a mass of vegetable matter, chiefly bog moss, which for centuries has been growing and accumulating on the spot. at the bottom of the bog will frequently be found trunks of oak, or other trees, the remains of a forest of former days. the wood has undergone chemical changes, has lost much of its moisture, and often become very hard, as in bog oak. beds of coal have been formed by a similar process, on a much vaster scale, and continued much longer. the remains of ancient forests have been buried under sand stones and other rocks, have undergone chemical change, and been compressed into the hard solid mass we call coal. fossil wood, which has not reached the stage of hard coal, but forms a soft brown substance, is called lignite. this is of frequent occurrence in various strata in the isle of wight. of organic rocks of animal origin the most remarkable are the chalk, of which we shall speak later, and the coral-reefs, which are found in the warm waters of tropical seas. sailing over the south pacific you will see a line of trees--coconut trees chiefly--looking as if they rose up from the sea. coming nearer you see that they grow on a low island, which rises only a few feet above the water. these islands are often in the form of a ring, and look "like garlands thrown upon the waters." inside the ring is a lagoon of calm water. outside the heavy swell of the southern ocean thunders on the coral shore. if a sounding line be let down from the outer edge of the reef, it will be found that the wall of coral goes down hundreds of feet like a precipice. on an island in the southern sea, funafuti, a deep boring has been made , ft. deep. as far as the boring went all was coral. all this mass of coral is formed by living things,--polyps they are called. they are like tiny sea anemones, only they grow attached to one another, forming a compound animal, like a tree with stem and branches, and little sea anemones for flowers. the whole organism has a sort of shell or skeleton, which is the coral. blocks are broken off by the waves, and ground to a coral mud, which fills up the interstices of the coral; and as more coral grows above, the lower part of the reef becomes, by pressure and cementing, a solid coral limestone. once upon a time there were coral islands forming in a sea, where now is england. these old coral reefs form beds of limestone in devon, derbyshire, and other parts of england. in the isle of wight we have no old coral reefs, but we shall easily find fossil corals in the rocks. they helped to make up the rocks, but there were not enough here to make reefs or islands all of coral. the great branching corals that form the reefs can only live in warm waters. so we see that when corals were forming reefs where now is england the climate must have been warm like the tropics. that is a story we shall often read as we come to hear more about the rocks. we shall find that the climate has often been quite warm as the tropics are now: and we shall also read another wonderful story of a time when the climate was cold like the arctic regions. chapter ii. the structure of the island. the best place to begin the study of the geology of the isle of wight is in sandown bay. north of sandown, beyond the flat of the marshes, are low cliffs of reddish clay, which has slipped in places, and is much covered by grass. at low tide we shall see the coloured clays on the shore, unless the sand has covered them up. variegated marls they are called--_marl_ means a limy clay, _loam_ a sandy clay; and very fine are the colours of these marls, rich reds and purples and browns. beyond the little sea wall below yaverland battery we come to a different kind of clay forming the cliff. it is in thin layers. clay in thin layers like this is called _shale_. some of these shales are known as paper shales, for the layers are thin almost like the leaves of a book. the junction of the shales with the marls is quite sharp, and we see that the shales rest on the coloured marls, not horizontally, but sloping down towards the north. bands of limestone and sandstone running through the shales, and a hard band of brown rock which runs out on the shore as a reef, slope in the same direction. as we pass on by the red cliff to the white cliffs we notice that the strata slope more steeply the further north we go. we have seen that these strata were laid down layer by layer at the bottom of the sea. if we find a lot of things lying one on top of another, we may generally conclude that the ones at the bottom were put there first, then the next, and so on to the top. and this will generally be true with regard to the rocks. the lowest rocks must have been laid down first, then the next, and so on. but these layers of shale with shells in them, and layers of limestone made of shells, must have been laid down at first fairly flat on the sea floor; but as they were upheaved out of the sea they have been tilted, so that we now see them in an inclined position. and when we come to the chalk, we should see, if we looked at the end of the culver cliffs from a boat, that the lines of black flints that run through the chalk are nearly vertical. the strata there have been tilted up on end. [illustration: fig. .] diagram of coast, sandown bay, dunnose to culver cliff. w _wealden._ p _perna bed._ lg _lower greensand._ cb _clay bands._ s _sandrock and carstone._ g _gault._ ug _upper greensand._ c _chalk._ sc _shanklin chine._ lc _luccombe chine._ in describing how strata lie, we call the inclination of the strata from the horizontal the _dip_. the direction of a horizontal line at right angles to that of the dip is called the _strike_. if we compare the sloping strata to the roof of a house, a line down the slope of the roof will mark the direction of the dip, the ridge of the roof that of the strike. the strata we are considering dip towards the north; the line of strike is east and west. returning towards sandown we see the strata dipping less and less steeply, till near the granite fort the rocks on the shore are horizontal. continuing our walk past sandown to shanklin we pass the same succession of rocks we have been looking at, but in reverse order, and sloping the other way. it is not very easy to see this at first, for so much is covered by building; but beyond sandown we see sandstone cliffs like the red cliff again, the strata dipping gently now to the south, and in the downs above shanklin we see the chalk again. so we have the same strata north and south of sandown, forming a sort of arch. but the centre of the arch is missing. it must have been cut away. we saw that the land was all being eaten away by rain and rivers. now we see what they have done here. go up on to the downs, and look over the central part of the island. we see two ranges of downs running from east to west,--the central downs of the island, a long line of chalk down miles from the culver cliff on the east to the needles on the west; and the southern downs along the south coast from shanklin to chale. in the central downs the chalk rises nearly vertically, and turns over in the beginning of an arch towards the south. then comes a big gap, and the chalk appears again in the southern downs nearly horizontal, sloping gently to the south. the chalk was once joined right across the central hollow, where now we see the villages of newchurch, godshill, and arreton. all that enormous mass of rock that once filled the space between the downs has been cut away by running water. an arch of strata like this [inverted-u], such as the one we are looking at, is called an _anticline_. when the arch is reversed, like this [u], it is called a _syncline_. looking north from the central downs over the solent we are looking at a syncline. the chalk, which dips down at the culvers and along the line of the central downs, runs like a trough under the solent, and rises again, as we see it on the other side, in the portsdown hills. we might suppose the top of an anticlinal arch would be the highest part of the country; that, even if rain and running water have worn the country down, that would still stand highest, and be worn down least. but there are reasons why this need not be so. for one thing, when the horizontal strata are curved over into an arch, they naturally crack just at the top of the curve, so and into the cracks the rain gets, and so a stream is started there, which cuts down and widens its channel, and so eats the land away. again, the rising land only emerges gradually from the sea, and the sea may cut off the top of the arch before it has risen out of its reach. moreover on the higher land the fall of rain and snow is greater, and the frosts are more severe; so that it is just there that the forces wearing down the land are most effective. [illustration: curve with two v-shaped marks at center] we must notice another thing which happens when rocks are being upheaved and bent into curves. the strain is very great, and sometimes the strata crack and one side is pushed up more than the other. these cracks are called _faults_. at little stairs, about half way between sandown and shanklin, two or three faults may be seen in the cliff. the effect of two of the faults may be easily seen by noticing the displacement of a band of rock stained orange by water containing iron. the strata are thrown down towards the north about ft. a third fault, the effect of which is not so evident at first sight, throws the strata down roughly ft. to the south. these are only small faults, but sometimes faults occur, in which the strata have been moved on opposite sides of the fault thousands of feet away from one another. we might think we should see a wall of rock rising up on the surface of the ground where a fault occurs; but the faults have mostly taken place ages ago; and, when they do happen, the rocks are generally moved only a little way at a time. then after a while another push comes on the rocks, and they shift again at the same place, and go a bit further. all this time frost and rain and rivers are working at the surface, and planing it down; so that the unevenness of the surface caused by faults is smoothed away; and so even a great fault does not show at the surface. as we follow the sandown anticline westward it gradually dies away, the upheaved area being actually a long oval--what we may call a turtle-back. as the sandown anticline dies out, it is succeeded by another a little further south, the brook anticline. there are in fact a series of these east and west anticlines in the island and on the adjacent mainland, caused by the same earth movement. as a consequence of the arching of the strata we find the lowest beds we saw in sandown bay running out again on the west of the island in brook bay, and a general correspondence of the strata on the east and west of the island; while, as we travel from sandown or brook northward to the solent, we come to continually more recent beds overlying those which appear to the south of them. when, as in the south side of our central downs, the strata are sharply cut away by denudation, we call this an _escarpment_. the figure shows the structure of the sandown anticline we have described. we must now examine the rocks more closely, beginning with the lowest strata in the island, and try to read the story they have to tell. chapter iii the wealden strata: the land of the iguanodon the lowest strata in the isle of wight are the coloured marls and blue-grey shales we have already observed in sandown bay, which run through the island to brook bay. they are known as the wealden strata, because the same strata cover the part of kent and sussex called the weald. they consist of marls and shales with bands of sandstone and limestone. the marls and shales in wet weather become very soft, and flow out on to the shore, causing large slips of land.[ ] now, what we want to find out is what the world was like ages ago, when these wealden strata were being formed. we have learnt something of how clays and sandstones and limestones are formed: to learn more we must see what sort of fossils we can find in these rocks. "fossil" means something dug up; and the word is generally used for remains of animals or plants which we find buried in the rocks. we have seen shells in these strata. these we must examine more closely. and as we walk on the shore we shall find other fossils. in the marls and shales exposed on the shore we are pretty sure to see pieces of wood, black as coal, sometimes quite large logs, often partly covered with shining iron pyrites. perhaps you say--i hope you do--there must have been land not far away when these marls and shales were forming. always try to see what the things we find have to tell us. the sort of place where we should be most likely to find wood floating in the sea to-day would be near the mouth of a great river like the mississippi or the amazon,--rivers which bring down numerous logs of wood from the forest country through which they flow. examine the shales and limestone bands. on the surface of some of the paper-shales are numbers of small round or oval white spots. they are the remains of shells of a very minute crustacean, cypris and cypridea, from which the shales are known as cyprid shales. in other bands of shale are quantities of a bivalve shell called _cyrena_. there is a band of limestone made up of cyrena shells, containing also little roundish spiral shells called _paludina_.[ ] this limestone resembles that called sussex or petworth marble, which is mainly composed of shells of paludina, but some layers also contain bivalve shells. it is hard enough to take a good polish, and may be seen, like the similar purbeck marble, in some of our grand old churches. another band of limestone running through the shales is made up of small oysters (_ostrea distorta_). we shall see fossil shells best on the _weathered_ surfaces of rocks, _i.e._, surfaces which have been exposed to the weather. one beginning geological study will probably think we shall find fossils best by looking at fresh broken surfaces of rock. this is not so. if you want to find fossils, look at the rock where it has been exposed to the weather. the action of the weather--rain, carbonic dioxide in the rain water, etc.--is to sculpture the surface of the rock, so that the fossils stand out in relief. a weathered surface is often seen covered with fossils, when a new broken one shows none at all. many of the shells in the limestones are very like shells which are found at the present day. we must know where they are found now. well, these paludinas are a kind of freshwater snail; and, in fact, all the shells we find in the wealden strata are freshwater shells, till we come near the top, and find the oysters, which live in salt or brackish water. there were quantities in brading harbour in old days, before it was reclaimed from the sea. now, this is a very important point, that our wealden shells are freshwater shells. for what does it tell us? why, we see that the first strata we have come to examine were not laid down in the sea at all. then where were they formed? they seem to be the delta of a great river, long since passed away, like the nile, the amazon, or the niger at the present day. when these great rivers near the sea, they spread out in many channels, and deposit the mud they have brought down over a wide area shaped like a v, or like the greek letter $delta$ (delta). hence we speak of the delta of the nile. some river deltas are of immense size. that of the niger, for instance, is miles long, and the line where it meets the sea is miles long. our old wealden river must have been a great river like the niger, for the wealden strata stretch,--often covered up for a long way by later rocks, then appearing again,--as far as lulworth on the dorset coast to the west, into buckinghamshire on the north, while to the north east they not only cover the weald, but pass under the straits of dover into belgium, and very similar strata are found in westphalia and hanover. the ancient river delta must have been miles or more across. you must not think this great river flowed in the island of england as it is to-day. england was being made then. this must have been part of a great continent in those days, for such a great river to flow through, and form a delta of such size. we cannot tell quite what was the course of this river. but to the north of where we are now must have stretched a great continent, with chains of lofty mountains far away, from which the head waters of the river flowed. near its mouth the river broke up into many streams, separated by marsh land; while inside the sand banks of the sea shore would be large lagoons as in the nile delta at the present day. in these waters lived the shellfish whose shells we are finding. and flowing through great forests the river carried down with it logs of wood and whole trees, and left them stuck in the mud near its mouths for us to find to-day. what kind of trees grew in the country the river came from? well, there were no oaks or beeches, no flowering chestnuts or apples or mays. but there were great forests of coniferous trees; that is trees like our pines and firs, cedars and yews, and araucarias; and there were cycads--a very different kind of tree, but also bearing cones--which you may see in a greenhouse in botanical gardens. they have usually a short trunk, sometimes nearly hemispherical, with leaves like the long leaves of a date palm. they are sometimes called sago trees, for the trunk has a large pith, which, like some palms, gives us sago. stems of cycads, covered with diamond-shaped scars, where the leaf stalks have dropped off, are found in the wealden deposits. most of the wood we find is black and brittle. some, however, is hard as stone, where the actual substance of the wood has been replaced by silica, preserving beautifully the structure of the wood. specially noteworthy are fragments of a tree called _endogenites_ (or _tempskya_) _erosa_, because it was at first supposed to belong to the endogens,--the class to which the palm bamboo belong; it is now considered to be a tree-fern. many specimens of this wood are remarkably beautiful, when polished, or in their natural condition. here, by the way, it may be well to explain how we name animals and plants scientifically. we have english names only for the commoner varieties. so we have to invent names for the greater number of living and extinct animals and plants. and the best way is found to be this. we give a name, generally formed from the latin--or the greek--to a group of animals or plants, which closely resemble one another; the group we call a _genus_. then for the _species_, the particular kind of animal or plant of the group, we add a second name to the first. thus, if we are studying the apple and pear group of fruit trees, we call the general name of the group _pyrus_. then the crab apple is _pyrus malus_, the wild pear _p. communis_, and so on. so that when you arrange any of your species, and put down the scientific names, you are really doing a bit of classification as well. you are arranging your specimens with their nearest relations. to return to our ancient river. with the logs and trunks of trees, which the river brought down, came floating down also the bodies of animals, which had lived in the country the river flowed through. what kind of animals? very wonderful animals, some of them, not like any living creature that lives to-day. by the time they reached the mouth of the river the bodies had come to pieces, and their bones were scattered about the river mouth. on the shore where we are walking we may find some of these bones. but it is rather a chance whether we find any in any one walk we take. the best time to find them is when rough seas in winter have washed some out of the clay, and left them on the shore. it is only rarely that large bones are found here; but you should be able to find some small ones fairly often. the bones are quite as heavy as stone, for all the pores and cavities have been filled with stone, generally carbonate of lime, in the way we explained in describing the formation of beds of limestone. this makes them quite different from any present-day bones that may happen to lie on the shore. so that you cannot mistake them, if once you have seen them. they are bones of great reptiles,--the class of creatures to which lizards and crocodiles belong. but these were much larger than crocodiles, and quite peculiar in their appearance. the principal one was the iguanodon. he stood on his hind legs like a kangaroo, with a great thick tail, which may have helped to support him. when full grown he stood about ft. high. you may find on the shore vertebræ, _i.e._, joints of the backbone, sometimes large, sometimes quite small if they come from the end of the tail. i have found several here about inches long by or across. a few years ago i found the end of a leg bone almost a foot in diameter. dr. mantell, a great geological explorer in the days when these reptiles were first discovered about years ago, estimated from the size of part of a bone found in sandown bay that one of these reptiles must have had a leg ft. long. it was a long time after the bones of these creatures were first found before it was known what they really looked like. the animals lived a long way from here, and by the time the river had washed them down to its mouth the skeletons were broken up, and the bones scattered. at last a discovery was made, which told us what the animals were like. in a coal mine at bernissart in belgium the miners found the coal seam they were following suddenly come to an end, and they got into a mass of clay. after a while it was seen what had happened. they had struck the buried channel of an old river, which in the wealden days had flowed through and cut its channel in the coal strata, which are much older still than the wealden. and in the mud of the ancient buried river what should they come upon but whole skeletons of iguanodons. in the days of long ago the great beasts had come down to the river to drink, and had got "bogged" in the soft clay. the skeletons were carefully got out, and set up in the museum at brussels. without going so far as that, you may see in the natural history museum in london, or the geological museum at oxford, a facsimile of one of these skeletons, large as life, and have some idea of the sort of beast the iguanodon was. i should tell you why he was so named. before it was known what he was like in general form, it was found that his teeth, which are of a remarkable character, were similar to those of the iguana, a little lizard of the west indies. so he was called iguanodon,--an animal with teeth like the iguana (fr. _iguana_, and gk. $odous$ g. $odontos$ a tooth). he was quite a harmless beast, though he was so large. he was a vegetarian. there were other great reptiles, more or less like him, which were also vegetable feeders. but there were also carnivorous reptiles, generally smaller than the herbivorous, whose teeth tell us that they preyed on other animals. [illustration: pl. i] perna mulleti meyeria vectensis (atherfield lobster) panopæa plicata terebratula sella cyrena limestone iguanodon vertebra wealden and lower greensand those were the days of reptiles. now the earth is the domain of the mammalia. but then great reptiles like the iguanodon wandered over the land; great marine reptiles, such as the plesiosaurus, swam the waters; and wonderful flying reptiles, the pterodactyls, flew the air. some species of these were quite small, the size of a rook: one large species found in the isle of wight had a spread of wing of feet. imagine this strange world,--its forests with pines and monkey puzzles and cycads,--ferns also, of which many fragments are found,--its great reptiles and little reptiles, on land, in the water and the air. were there no birds? yes, but they were rare. from remains found in oolitic strata,--somewhat older than the wealden,--we know that birds were already in existence; and they were as strange as anything else. for they had jaws with teeth like the reptiles. they had not yet adopted the beak. and instead of all the tail feathers starting from one point, as in birds of the present day, these ancient birds had long curving tails like reptiles, with a pair of feathers on each joint. birds of similar but slightly more modern type have been found in cretaceous strata (to which the wealden belongs) in america, but so far not in strata of this age in britain. among other objects of interest along this wealden shore may be noticed a curious transformation which has affected the surface of some of the shell limestones after they were formed, which is known as cone-in-cone structure. it has quite altered the outer layer of the rock, so that all trace of the shells of which it consists is obliterated. numerous pieces of iron ore from various strata lie on the shore. through most of english history the weald of kent and sussex was the great iron-working district of england. the ore from the wealden strata was smelted by the help of charcoal made from the woods that grew there, and gave the district its name;--for _weald_ means "forest." this industry gradually ceased, as the much larger supplies of iron ore found near the coal in the mines of the north of england came to be worked. iron pyrites, sulphide of iron in crystalline form, was formerly collected on the sandown shore, and sent to london for the manufacture of sulphuric acid. this mineral is often found encrusting fossil wood. it also occurs as rounded nodules (mostly derived from the lower chalk) with a brown outer coat, and often showing a beautiful radiated metallic structure, when broken. (this form is called marcasite.) as we walk by the edge of the water, we shall see what pretty stones lie along the beach. when wet with the ripples many look like polished jewels. some are agates, bright purple and orange in colour, some clear translucent chaldedony. we shall have more to say about these later on. they do not come from the wealden, but from beds of flint gravel, and are washed along the shore. but there are also jaspers from the wealden. these are opaque, generally red and yellow. there are also pieces of variegated quartz, and other beautiful pebbles of various mineral composition. these are stones from older rocks, which have been washed down the wealden rivers, and buried in the wealden strata, to be washed out again after hundreds of thousands of years, and rolled about on the shore on which we walk to-day. [footnote : blue clays of various geological age, which in wet weather become semi-liquid, and flow out on to the shore, are known in the island by the local name of _blue slipper_.] [footnote : the name now adopted is _viviparus_. there is also a band of ferruginous limestone mainly composed of _viviparus_.] [illustration: pl. ii] trigonia caudata trigonia dædalea gervillia sublanceolata (ammonite) nautilus radiatus mortoniceras rostratum lower and upper greensand chapter iv the lower greensand for ages the wealden river flowed, and over its vast delta laid down its depth of river mud. the land was gradually sinking; for continually strata of river mud were laid down over the same area, all shallow-water strata, yet counting hundreds of feet in thickness in all. at last a change came. the land sank more rapidly, and in over the delta the sea water flowed. the sign of coming change is seen in the limestone band made up of small oysters near the top of the wealden strata. marine life was beginning to appear. above the wealden shales in sandown bay may be seen a band of brown rock. it is in places much covered by slip, but big blocks lie about the shore, and it runs out to sea as a reef before we come to the red cliff. the blocks are seen to consist of a hard grey stone, but the weathered surfaces are soft and brown. they are full of fossils, all marine, sea shells and corals. the sea has washed in well over our wealden delta, and with this bed the next formation, the lower greensand, begins. the bed is called the perna bed, from a large bivalve shell (_perna mulleti_) frequently to be found in it, though it is difficult to obtain perfect specimens showing the long hinge of the valve, which is a marked feature of the shell. among other shells are a large round bivalve _corbis_ (_sphæra_) _corrugata_, a flatter bivalve _astarte_,--and a smaller oblong shell _panopæa_,--also a peculiar shell of triangular form, _trigonia_,--one species _t. caudata_ has raised ribs running across it, another _t. dædalea_ has bands of raised spots. a pretty little coral, looking like a collection of little stars, _holocystis elegans_, one of the astræidæ, is often very sharply weathered out. above the perna bed lies a mass of blue clay, weathering brown, called the atherfield clay, because it appears on a great scale at atherfield on the south west of the island. it is very like the clay of the wealden shales, but is not divided into thin layers like shale. next we come to the fine mass of red sandstone which forms the vertical wall of red cliff. not many fossils are to be found in these strata. let us note the beauty of colouring of the red cliff--pink and green, rich orange and purple reds. and then let us pass to the other side of the anticline, and walk on the shore to shanklin. here we see the red sandstone rocks again, but now dipping to the south. you probably wonder why these red cliffs are called greensand. but look at the rocks where they run out as ledges on the shore towards shanklin. here they are dark green. and this is really their natural colour. they are made of a mixture of sand and clay coloured dark green by a mineral called glauconite. grains of glauconite can easily be seen in a handful of sand,--better with a magnifying glass. this mineral is a compound of iron, with silica and potash, and at the surface of the rock it is altered chemically, and oxide of iron is formed--the same thing as rust. and that colours all the face of the cliff red. the iron is also largely responsible for our finding so few fossils in these strata. by chemical changes, in which the iron takes part, the material of the shells is destroyed.[ ] near little stairs hollows in the rock may be seen, where large oyster shells have been. in some you may find a broken piece of shell, but the shells have been mostly destroyed. nearer shanklin we shall find large oysters, _exogyra sinuata_, in the rock ledges exposed at low tide. some are stuck together in masses. evidently there was an oyster bank here. and here the shells have not been destroyed like those in the cliff. from black bands in the cliff water full of iron oozes out, staining the cliff red and yellow and orange, and trickling down, stains the flint stones lying on the shore a bright orange. at the foot of the cliff you may sometimes see what looks like a bed of conglomerate, _i.e._, a bed of rounded pebbles cemented together. this does not belong to the cliff, but is made up of the flint pebbles on the shore, and the sand in which they lie, cemented into a solid mass by the iron in the water which has flowed from the cliff. it is a modern conglomerate, and shows us how old conglomerates were formed, which we often find in the various strata. the cement, however, in these is not always iron oxide. it may be siliceous or of other material. the iron-charged water is called chalybeate; springs at shanklin and niton at one time had some fame for their strengthening powers. the strata we have been examining are known as the ferruginous sands, _i.e._, iron sands (lat. _ferrum_, "iron"). beyond shanklin is a fine piece of cliff. look up at it, but beware of going too close under it. the upper part consists of a fine yellow sand called the sandrock. at the base of this are two bands of dark clay. these bands become filled with water, and flow out, causing the sandrock which rests on them to break away in large masses, and fall on to the beach. it is clay bands such as these which are the cause of our undercliffs in the isle of wight. turn the point, and you see exactly how an undercliff is formed. you see a wide platform at the level of the clay, which has slipped out, and let down the sandrock which rested on it. beyond luccombe chine a large landslip took place in , a great mass of cliff breaking away, and leaving a ravine behind partly filled with fallen pine trees. the whole fallen mass has since sunk lower and nearer to the sea. the broken ground overgrown with trees called the landslip, as well as the whole extent of the ground from ventnor and niton, has been formed in a similar way. but the clay which by its slip has produced these is another clay called the gault, higher up in the strata. at the top of the high cliff near luccombe chine a hard gritty stratum of rock called the carstone is seen above the sandrock, and above it lies the gault clay, which flows over the edge of the cliff. in the rock ledges and fallen blocks of stone between shanklin and luccombe many more fossils may be found than in the lower part of the ferruginous sands. besides bands of oysters, blocks of stone are to be found crowded with a pretty little shell called _rhynchonella_. there are others with many _terebratulæ_, and others with fragments of sea urchins. the terebratulæ and rhynchonellæ belong to a curious group of shells, the brachiopods, which are placed in a class distinct from the mollusca proper. they were very common in the very ancient seas of the cambrian period,--the period of the most ancient fossils yet found,--and some, the lingulæ, have lived on almost unchanged to the present day. one of the two valves is larger than the other, and near the smaller end you will see a little round hole. out of this hole, when the creature was alive, came a sort of neck, which attached it to the rock, like the barnacles. there is a very hard ferruginous band, of which nodules may be found along the shore, full of beautifully perfect impressions of fossils, though the fossils themselves are gone. casts of a little round bivalve shell, _thetironia minor_, may easily be got out. the nodules also contain casts of trigonia, panopoea, etc. a stratum is sometimes exposed on the shore containing fossils converted into pyrites. a long shell, _gervillia sublanceolata_, is the most frequent. all the shells we have found are of sea creatures, and show us that the greensand was a marine formation. but the strata were formed in shallow water not far from the shore. we have learnt that coarse sediment like sand is not carried by the sea far from the coast. and a good deal of the greensand is coarser than sand. there are numerous bands of small pebbles. the pebbles are of various kinds; some are clear transparent quartz, bits of rock-crystal more or less rounded by rolling on the shore of the greensand period. these go by the name of isle of wight diamonds, and are very pretty when polished. another mark of the nearness of the shore when these beds were laid down is the current bedding, of which a good example may be seen in the cliff at the north of shanklin parade. it is sometimes called false bedding, for the sloping bands do not mark strata laid down horizontally at the bottom of the sea, but a current has laid down layers in a sloping way,--it may be just over the edge of a sandbank. again notice how much wood is to be seen in the strata. land was evidently not far off. all along the shore you may find hard pieces of mineralised wood, the rings of growth often showing clearly. frequently marine worms have bored into them before they were locked up in the strata; the holes being generally filled afterwards with stone or pyrites. the wood is mostly portions of trunks or branches of coniferous trees. we also find stems of cycads. there has been found at luccombe a very remarkable fruit of a kind of cycad. we said that in the wealden period none of our flowering plants grew. but these specimens found at luccombe show that cycads at that time were developing into flowering plants. wonderful specimens of what may almost be called cycad flowers have been found in strata of about this age in wyoming in america; and this luccombe cycad,--called benettites gibsonianus,--shows what these were like in fruit. remains of various cycadeous plants have been found in the corresponding strata at atherfield; and possibly by further research fresh knowledge may be gained of an intensely interesting story,--the history of the development of flowering plants. on the whole the vegetation of the period was much the same as in the wealden. but these flowering cycads must have formed a marked addition to the landscape,--if indeed they did not already exist in the wealden times. the cones of present day cycads are very splendidly coloured,--orange and crimson,--and it can hardly be doubted that the cycad flowers were of brilliant hues. the land animals were still like the wealden reptiles. bones of large reptiles may at times be found on the shore at shanklin. several have been picked up recently. from the prevalence of cycads we may conclude that the climate of the wealden and lower greensand was sub-tropical. the existing cycadaceæ are plants of south eastern asia, and australia, the cape, and central america. the forest of trees allied to pines and firs and cedars probably occupied the higher land. turtles and the corals point to warm waters. the existing species of trigonia are australian shells. this beautiful shell is found plentifully in sydney harbour. it possesses a peculiar interest, as the genus was supposed to be extinct, and was originally described from the fossil forms, and was afterwards found to be still living in australia. [footnote : carbonate of lime has been replaced by carbonate of iron, and the latter converted into peroxide of iron. at sandown oxidation has gone through the whole cliff.] [illustration: fig. ] coast atherfield to rocken end wl _wealden beds._ p _perna bed._ a _atherfield clay._ ck _cracker group._ lg _lower gryphæa beds._ sc _scaphite. "_ lc _lower crioceras "_ w _walpen clay._ uc _upper crioceras beds._ ws _walpen and ladder sands._ ug _upper gryphæa beds._ ce _cliff end sands._ f _foliated clay._ su _sands of walpen undercliff._ fer _ferruginous bands of blackgang chine._ b _black clay._ s _sandrock and clays._ wh _whale chine._ l _ladder chine._ wp _walpen chine._ bg _blackgang chine._ chapter v brook and atherfield to most sandown bay is by far the most accessible place in the island to study the earlier strata; and for our first geological studies it has the advantage of showing a succession of strata so tilted that we can pass over one formation after another in the course of a short walk. but when we have learnt the nature of geological research, and how to read the record of the rocks, and examined the wealden and greensand strata in sandown bay, we shall do well, if possible, to make expeditions to brook and atherfield, to see the splendid succession of wealden and greensand strata shown in the cliffs of the south-west of the island. it is a lonely stretch of coast, wild and storm-swept in winter. but this part of the island is full of interest and charm to the lover of nature and of the old-world villages and the old churches and manor houses which fit so well into their natural surroundings. the villages in general lie back under the shelter of the downs some distance from the shore; a coastguard station, a lonely farm house, or some fishermen's houses as at brook, forming the only habitations of man we come to along many miles of shore. brook point is a spot of great interest to the geologist. here we come upon wealden strata somewhat older than any in sandown bay. the shore at the point at low tide is seen to be strewn with the trunks of fossil trees. they are of good size, some ft. in length, and from one to three feet in diameter. they are known as the pine raft, and evidently form a mass of timber floated down an ancient river, and stranded near the mouth, just as happens with great accumulations of timber which float down the mississippi at the present day. the greater part of the wood has been replaced by stone, the bark remaining as a carbonaceous substance like coal, which, however, is quickly destroyed when exposed to the action of the waves. the fossil trees are mostly covered with seaweed. on the trunks may sometimes be found black shining scales of a fossil fish, _lepidotus mantelli_. (a stratum full of the scales of _lepidotus_ has been recently exposed in the wealden of sandown bay.) the strata with the pine raft form the lowest visible part of the anticline. from brook point the wealden strata dip in each direction, east and west. as the coast does not cut nearly so straight across the strata as in sandown bay, we see a much longer section of the beds. on either side of the point are coloured marls, followed by blue shales, as at sandown. to the westward, however, after the shales we suddenly come to variegated marls again, followed by a second set of shales. there was long a question whether this repetition is due to a fault, or whether local conditions have caused a variation in the type of the beds. the conclusion of the geological survey memoir, , rather favoured the latter view, on the ground of the great change which has taken place in the character of the beds in so short a distance, assuming them to be the same strata repeated. the conjecture of the existence of a fault has, however, been confirmed; for during the last years a most interesting section has been visible at the junction of the shales and marls, where a fault was suspected. the shales in the cliff and on the shore are contorted into the form of a z. the section appears to have become visible about (it was in the spring of that year that i first saw it), and was described by mr. r. w. hooley, f.g.s. (_proc. geol. ass._, vol. xix., , pp. , ). it has remained visible since. the wealden of brook and the neighbouring coast is celebrated for the number of bones of great reptiles found here, from the early days of geological research, the ' 's and ' 's of last century, when admirable early geologists, such as dr. buckland and dr. mantell, were discovering the wonders of that ancient world, to the present time. various reptiles have been found besides the iguanodon--the megalosaurus, a great reptile somewhat similar, but of lighter build, with sabre-shaped teeth, with serrated edges: the hylæosaurus, a smaller creature with an armour of plates on the back, and a row of angular spines along the middle of the back; the huge _hoplosaurus hulkei_, probably or feet in length; the marine plesiosaurus and ichthyosaurus, and several more; also bones of a freshwater turtle and four types of crocodiles. in various beds a large freshwater shell, _unio valdensis_, occurs, and in the cliffs of brook have been found many cones of cycadean plants. in bands of white sandy clay are fragments of ferns, _lonchopteris mantelli_. in the shales are bands of limestone with cyrena, paludina, and small oysters, and paper shales with cyprids, as at sandown. the shore near atherfield point is covered with fallen blocks of the limestones. the lower greensand is seen in compton bay on the northern side of the brook anticline. here is a great slip of atherfield clay. the beds above the clay are much thinner than at atherfield, and fossils are comparatively scarce. on the south of the anticline the perna bed slopes down to the sea about yards east of atherfield point, and runs out to sea as a reef. large blocks lie on the shore, where numerous fossils may be found on the weathered surfaces. the ledges which here run out to sea form a dangerous reef, on which many vessels have struck. there is now a bell buoy on the reef. on the headland is a coastguard station, and till lately there has been a sloping wooden way from the top of the cliff to bring the lifeboat down. this was washed away in the storms of the winter - . above the perna bed lies a great thickness of atherfield clay. above this lies what is called the lower lobster bed, a brown clay and sand, in which are numerous nodules containing the small lobster _meyeria vectensis_,--known as atherfield lobsters. many beautiful specimens have been obtained. we next come to a great thickness of the ferruginous sands, some feet. the lower greensand of atherfield was exhaustively studied in the earlier days of geology by dr. fitton, in the years - , and the different strata are still referred to according to his divisions. the lowest bed is the crackers group about ft. thick. in the lower part are two layers of hard calcareous boulder-shaped concretions, some a few feet long. the lower abound in fossils, and though hard when falling from the cliffs are broken up by winter frosts, showing the fossils they contain beautifully preserved in the softer sandy cores of the concretions. _gervillia sublanceolata_ is very frequent, also _thetironia minor_, the ammonite _hoplites deshayesi_, and many more. beneath and between the nodular masses caverns are formed, the resounding of the waves in which has given the name of the "crackers." in the upper part of this group is a second lobster bed. the most remarkable fossils in the lower greensand are the various genera and species of the ammonites and their kindred. the ammonite, through many formations, was one of the largest, and often most beautiful shells. there were also quite small species. the number of species was very great. now the whole group is extinct. they most resembled the pearly nautilus, which still lives. in both the shell is spiral, and consists of several chambers, the animal living in the outer chamber, the rest being air-chambers enabling it to float. the class cephalopoda, which includes the ammonites, the nautilus, and also the cuttle-fish, is the highest division of the mollusca. the animals all possess heads with eyes, and tentacles around the mouth. they nearly all possess a shell, either external, as in the nautilus, or internal, as in the cuttle-fishes, the internal shell of which is often washed ashore after a rough sea. the cephalopods are divided into two orders. the first includes the cuttle-fish and the argonaut or paper nautilus. their tentacles are armed with suckers, and they have highly-developed eyes. they secrete an inky fluid, which forms sepia. the internal shell of extinct species of cuttle-fish, of a cylindrical shape, with a pointed end, is a common fossil in various strata, and is known as a belemnite (gr. $belemnon$ "a dart".) the second order includes the pearly nautilus of the present day, and the numerous extinct nautiloids and ammonoids. the tentacles of the pearly nautilus have no suckers; and the eyes are of a curiously primitive structure,--what may be called a pin-hole camera, with no lens. the shells of the nautilus and its allies are of simpler form, while the ammonites are characterised by the complicated margins of the partition walls or septa, by which the shells are sub-divided. the chambers of the fossil ammonites have often been filled with crystals of rich colours; and a polished section showing the chambers is then a most beautiful object.[ ] continuing along the shore, we come to the lower exogyra group, where _terebratula sella_ is found in great abundance. a reef with _exogyra sinuata_ runs out about yards west of whale chine. the group is ft. thick, and is followed by the scaphites group, ft. the beds contain _exogyra sinuata_, and a reef with clusters of serpulæ runs out from the cliff. in the middle of the group are bands of nodules containing _macroscaphites gigas_. the lower crioceras bed ( ft.) follows, and crosses the bottom of whale chine. the scaphites and crioceras are cephalopoda, related to the ammonites; but in this lower cretaceous period a remarkable development took place; many of the shells began to take curious forms, to unwind as it were. crioceras, a very beautiful shell, has the form of an ammonite, but the whorls are not in contact; thus making an open spiral like a ram's horn, whence its name (gk. $keras$, ram, $krios$, horn). ancyloceras begins like crioceras, but from the last whorl continues for some length in a straight course, then bends back again; macroscaphites is similar, but the whorls of the spiral part are in contact. in scaphites, a much smaller shell, the uncoiled part is much shorter, and its outline more rounded. it is named from its resemblance to a boat (gk. $skaphê$).[ ] the walpen and ladder clays and sands (about ft.) contain nodules with exogyra and the ammonite _douvilleiceras martini_. the dark-green clays of the lower part form an undercliff, on to which ladder chine opens. the upper crioceras group ( ft.), like the lower, contains bands of crioceras? also _douvilleiceras martini_, gervillia, trigonia, etc. it must be stated that there is some uncertainty with regard to the ammonoids found in this neighbourhood, macroscaphites having been described as ancyloceras, and also sometimes as crioceras. the discovery of the true ancyloceras (_ancyloceras matheronianum_) at atherfield is described (and a figure given) by dr. mantell; but what is the characteristic ammonoid of the "crioceras" beds requires further investigation. the neighbourhood of whale and walpen chines is of great interest. ammonites may be found in the bottom of whale chine fallen out of the rock. red ferruginous nodules with ammonites lie on the shore, in the chines, and on the undercliff, some of the ammonites more or less converted into crystalline spar. hard ledges of the crioceras beds run into the sea. the shore is usually covered deep with sand and small shingle; but there are times when the sea has washed the ledges clear; and it is then that the shore should be examined. the walpen and ladder sands ( ft.); the upper exogyra group ( ft.); the cliff end sand ( ft.); and the foliated clay and sand ( ft.), consisting of thin alternations of greenish sand and dark-blue clay, follow. then the sands of walpen undercliff (about ft.); over which lie the ferruginous bands of blackgang chine ( ft.). over these hard beds the cascade of the chine falls. cycads and other vegetable remains are found in this neighbourhood. throughout the atherfield greensand fragments of the fern _lonchopteris_ (_weichselia_) _mantelli_ are found. ft. of dark clays and soft white or yellow sandrock complete the lower greensand. in the upper beds of the greensand few organic remains occur. a beautiful section of sandrock with the junction of the carstone is to be seen inland at rock above bright-stone. the sandrock here is brightly coloured like the sands of alum bay,--though it belongs to a much older formation,--and shows current bedding very beautifully. the junction of the sandrock and carstone is also well seen in the sandpit at marvel. we have now come to the end of the lower cretaceous, in which are included the wealden and the lower greensand. judged by the character of the flora and fauna, the two form one period, the main difference being the effect of the recession of the shore line, due to the subsidence which let in the sea over the wealden delta, so that we have marine strata in place of freshwater deposits. but that the plants and animals of the wealden age still lived in the not distant continent is shown by the remains borne down from the land. these strata are an example of a phenomenon often met with in geology,--that of a great thickness of deposits all laid down in shallow water. the wealden of the isle of wight are some feet thick, in kent a good deal thicker, the hastings sands, the lower part of the formation, being below the horizon occurring in the island: the lower greensand is some feet thick. in the ancient rocks of wales, the cambrian and silurian strata, are thousands of feet of deposits, mostly laid down in fairly shallow water. in such cases there has been a long-continued deposition of sediment, while a subsidence of the area in which it was laid down has almost exactly kept pace with the deposit. it is difficult not to conclude that the subsidence has been caused by the weight of the accumulating deposit,--continuing until some world-movement of the contracting globe has produced a compensating elevation of the area. [footnote : some fine ammonites may be seen at the clarendon hotel, chale,--one about ft. in circumference.] [footnote : _see guide to fossil invertebrata_, brit. mus. nat. hist.] chapter vi the gault and upper greensand we have seen how the continent through which the great wealden river flowed began to sink below the sea level, and how the waters of the sea flowed over what had been the delta of the river, laying down the beds of sandstone with some mixture of clay which we call the lower greensand. the next stratum we come to is a bed of dark blue clay more or less sandy, called the gault. in the upper beds it becomes more sandy and grey in colour. these are known as the "passage beds," passing into the upper greensand. the thickness of the gault clay proper varies from some to feet. compared to the mainland the gault is of small thickness in the island, though the dark clay bands in the sandrock mark the oncoming of similar conditions. the fine sediment forming the clay points to a further sinking of the sea bed. in general, we find very few fossils in the gault in the island, though it is very fossiliferous on the mainland at folkestone. north of sandown red cliff the gault forms a gully, down which a footpath leads to the shore. it is seen at the west of the island in compton bay, where in the lower part some fossil shells may be found. the upper greensand is not very well named, as the beds only partially consist of sandstone, in great part of quite other materials. some prefer to call the lower greensand vectian, from vectis, the old name of the isle of wight, and the upper greensand selbornian, a name generally adopted, because it forms a marked feature of the country about selborne in hampshire.[ ] but, though the upper greensand covers a less area in the isle of wight than the lower, it forms some of the most characteristic scenery of the island. one of the most striking features of the island is the undercliff, the undulating wooded country from bonchurch to niton, above the sea cliff, but under a second cliff, a vertical wall which shelters it to the north. this wall of cliff consists of upper greensand. in a similar way to the small undercliffs we saw at luccombe, the undercliff has been formed by a series of great slips, caused here by the flowing out of the gault clay, which runs in a nearly horizontal band through the base of all the southern downs of the island, the upper greensand lying above it breaking off in masses, and leaving vertical walls of cliff. these walls are seen not only in the undercliff, but also on the northern side of the downs, where they form the inland cliff overhanging a pretty belt of woodland from shanklin to cook's castle, and again forming gat cliff above appuldurcombe. we have records of great landslips at the two ends of the undercliff, near bonchurch and at rocken end, about a century ago. but the greater part of the undercliff was formed by landslips in very ancient times, before recorded history in this island began. the outcrop of the gault is marked by a line of springs on all sides of the southern downs. the strata above, chalk and upper greensand, are porous and absorb the rainfall, which permeates through till it reaches the gault clay, which throws it out of the hill side in springs, some of which furnish a water supply for the surrounding towns and villages. where the upper greensand is best developed, above the undercliff, the passage beds are followed by feet of yellow micaceous sands, with layers of nodules of a bluish-grey siliceous limestone known as rag. the nodules frequently contain large ammonites and other fossils. next follow the sandstone and rag beds, about feet of sandstone with alternating layers of rag. the sandstones are grey in colour, weathering buff or reddish-brown, tinged more or less green by grains of glauconite. near the top of these strata is the freestone bed, a thick bed of a close-grained sandstone, weathering a yellowish grey, which forms a good building stone. most of the churches and old manor and farm houses in the southern half of the island are built of this stone. then forming the top of the series are feet of chert beds,--bands of a hard flinty rock called chert alternating with siliceous sandstone, the sandstone containing large concretions of rag in the same line of bedding. the chert beds are very hard, and where the strata are horizontal, as above the undercliff, project like a cornice at the top of the cliff. perhaps the finest piece of the upper greensand is gore cliff above niton lighthouse, a great vertical wall with the cornice of dark chert strata overhanging at the top. the thickness in the undercliff, including the passage beds, is from to ft. the upper greensand may be studied at compton bay, and at the culvers; and along the shore west of ventnor the lower cliff by the sea consists largely of masses of fallen upper greensand, many of which show the chert strata well. in numerous walls in the south of the island may be seen stone from the various strata--sandstone, blue limestone or rag, and also the chert. let us think what was happening when these beds were being formed. the sandstone is much finer than that of the lower greensand; and we have limestones now,--marine, not freshwater as in the wealden. marine limestones are formed by remains of sea creatures living at some depth in clear water. and now we come to a new material, chert. it is not unlike flint, and flint is one of the mineral forms of silica. chert may be called an impure or sandy flint. the bands of chert appear to have been formed by an infiltration of silica into a sandstone, forming a dense flinty rock, which, however, has a dull appearance from the admixture of sand, instead of being a black semi-transparent substance like flint. but where did the silica come from? in the depths of the sea many sea creatures have skeletons and shells formed of silica or flint, instead of carbonate of lime, which is the material of ordinary shells and of corals. many sponges, instead of the horny skeleton we use in the washing sponge, have a skeleton formed of a network of needles of silica, often of beautiful forms. some marine animalcules, the radiolaria, have skeletons of silica. and minute plants, the diatoms, have coverings of silica, which remain like a little transparent box, when the tiny plant is dead. now, much of the chert is full of needles, or spicules, as they are called, of sponges, and this points to the source from which some at least of the silica was derived. to form the chert much of the silica has been in some manner dissolved, and deposited again in the interstices of sandstone strata. we shall have more to say of this process when we come to speak of the origin of the flints in the chalk. sponges usually live in clear water of some depth; so all shows that the sea was becoming deeper when these strata were being formed. along the shore of the undercliff, upper greensand fossils may be found nicely weathered out. very common is a small curved bivalve shell,--a kind of small oyster,--_exogyra conica_, as are also serpulæ, the tubes formed by certain marine worms. very pretty pectens (scallop shells) are found in the sandstone. many other shells, _terebratulæ_, _trigonia_, _panopæa_, etc., occur, and several species of ammonite and nautilus.[ ] a frequent fossil is a kind of sponge, siphonia. it has the form of an oblong bulb, supported by a long stem, with a root-like base. it is often silicified, and when broken shows bundles of tubular channels. in the chert may often be seen pieces of white or bluish chalcedony, generally in thin plates filling cracks in the chert. this is a very pure and hard form of silica, beautifully clear and translucent. pebbles which the waves have worn in the direction of the plate are very pretty when polished, and go by the name of sand agates. they may sometimes be picked up on the shore near the culvers. [footnote : names proposed by the late a. j. jukes-browne.] [footnote : of ammonites, _mortoniceras rostratum_ and _hoplites splendens_ may be mentioned: and of pectens, _neithea quinquecostata_ and _quadricostata_, _syncyclonema orbicularis_, and _Æquipecten asper_.] chapter vii the chalk as we have traced the world's history written in the rocks we have seen an old continent gradually submerged, a deepening sea flowing over this part of the earth's surface. now we shall find evidence of the deepening of the sea to something like an ocean depth. we are coming to the great period of the chalk, the time when the material was made which forms the undulating downs of the south-east of england, and of which the line of white cliffs consists, which with sundry breaks half encircles our shores, from flamborough head in yorkshire, by dover and the isle of wight, to bere in devon. across the channel white cliffs of chalk face those of england, and the chalk stretches inland into the continent. its extent was formerly greater still. fragments of chalk and flint are preserved in mull under basalt, an old lava flow, and flints from the chalk are found in more recent deposits (boulder clay) on the east of scotland, pointing to a former great extension northward, which has been nearly all removed by denudation. in the isle of wight the chalk cliffs of freshwater and the culvers are the grandest features of the island; while all the island is dominated by the long lines of chalk downs running through it from east to west. now what is the chalk? and how was it made? the microscope must tell us. it is found that this great mass of chalk is made up principally of tiny microscopic shells called foraminifera, whole and in crushed fragments. there are plenty of foraminifera in the seas to-day; and we need not go far to find similar shells. on the shore near shanklin you will often see streaks of what look like tiny bits of broken shell washed into depressions in the sand. these, however, often consist almost entirely of complete microscopic shells, some of them of great beauty. the creature that lives in one of these shells is only like a drop of formless jelly, and yet around itself it forms a complex shell of surprising beauty. the shells are pierced with a number of holes, hence their name (fr. lat. _foramen_, a hole, and _ferre_, to bear). through these holes the animal puts out a number of feelers like threads of jelly, and in these entangles particles of food, and draws them into itself. now, do we anywhere to-day find these tiny shells in such masses as to build up rocks? we do. the sounding apparatus, with which we measure the depths of the sea, is so constructed as to bring up a specimen of the sea bottom. this has been used in the atlantic, and it is found that the really deep sea bottom, too far out for rivers and currents to bring sand and mud from the land, is covered with a white mud or ooze. and the microscope shows this to be made up of an unnumerable multitude of the tiny shells of foraminifera. as the little creatures die in the sea, their shells accumulate on the bottom, and in time will be pressed into a hard mass like chalk, the whole being cemented together by carbonate of lime, in the way we explained in describing the making of limestones. so we find chalk still forming at the present day. but what ages it must take to form strata of solid rock of such tiny shells! and what a vast period of time it must have required to build up our chalk cliffs and downs, composed in large part of tiny microscopic shells! with the foraminifera the microscope shows in the chalk a multitude of crushed fragments, largely the prisms which compose bivalve shells, flakes of shells of terebratula and rhynchonella, and minute fragments of corals and bryozoa. scattered in the chalk we shall also find larger shells and other remains of the life of the ancient sea. the base of the cliffs and fallen blocks on the shore are the best places to find fossils. much of the base of the cliffs is inaccessible except by boat. the lower strata may be examined in sandown and compton bays, and the upper in whitecliff bay. a watch should always be kept on the tide. the quarries along the downs are not as a rule good for collecting, as the chalk does not become so much sculptured by weathering. the deep sea of the white chalk did not come suddenly. in the oncoming of the period we find much marl--limy clay. as the sea deepened, little reached the bottom but the shells of foraminifera and other marine organisms. how deep the sea became is uncertain: there is reason to believe that it did not reach a depth such as that of the atlantic. it is difficult to draw the line between the upper greensand and the chalk strata. above the chert beds is a band a few feet thick known as the chloritic marl, which shows a passage from sand to calcareous matter. it is named from the abundance of grains of green colouring matter, now recognised as glauconite; so that it would be better called glauconitic marl. it is also remarkable for the phosphatic nodules, and for the numerous casts of ammonites, turrilites, and other fossils mostly phosphatized, which it contains. this band is one of the richest strata in the island for fossils. it differs, however, in different localities both in thickness and composition. it is best seen above the undercliff, and in fallen masses along the shore from ventnor to niton. it is finely exposed on the top of gore cliff, where the flat ledges are covered with fossil ammonites, turrilites, pleurotomaria, and other shells. the ammonite (_schloenbachia varians_) is especially common. the sponge (_stauronema carteri_) is characteristic of the glauconitic marl. as the edge of the cliff is a vertical wall, none should try this locality but those who can be trusted to take proper care on the top of a precipice. when a high wind is blowing the position may be especially dangerous. [illustration: pl. iii] (pecten) neithea quinquecostata thetironia (ammonite) rhynchonella minor mantelliceras mantelli parvirostris (sea urchins) micraster cor-anguinum echinocorys scutatus (internal cast in flint) lower and upper greensand and chalk the chloritic marl is followed by the chalk marl, of much greater thickness. this consists of alternations of chalk with bands of marl, and contains glauconite and also phosphatic nodules in the lower part. upwards it merges into the grey chalk, a more massive rock, coloured grey from admixture of clayey matter. these form the lower chalk, the first of the three divisions into which the chalk is usually divided. above this come the middle and upper, which together form the white chalk. they are much purer white than the lower division, which is creamy or grey in colour. the chalk marl and grey chalk are well seen at the culver cliff, and run out in ledges on the shore. the lower part of this division is the most fossiliferous, and contains various species of ammonities, turrilites, nautilus, and other cephalopoda. (of ammonites _schloenbachia varians_ is characteristic. also may be named _s. coupei_, _mantelliceras mantelli_, _metacanthoplites rotomagensis_, _calycoceras naviculare_, the small ammonoid scaphites æqualis; and of pectens, _Æquipecten beaveri_ and _syncyclonema orbicularis_ may be mentioned). white meandering lines of the sponge _plocoscyphia labrosa_ are conspicuous in the lower beds. the chalk marl is well shown at gore cliff, sloping upwards from the flat ledges of the chloritic marl. it may be studied well, and fossils found, in the cliff on the ventnor side of bonchurch cove,--which has all slipped down from a higher level. the uppermost strata of the lower chalk are known as the belemnite marls. they are dark marly bands, in which a belemnite, _actinocamax plenus_, is found. the hard bands known as melbourn rock and chalk rock, which on the mainland mark the top of the lower and middle chalk respectively, are neither of them well marked in the isle of wight. in the middle chalk _inoceramus labiatus_, a large bivalve shell, occurs in great profusion; and in the upper flinty chalk are sheets of another species, _i. cuvieri_. it is hardly ever found perfect, the shells being of a fibrous structure, with the fibres at right angles to the surface, and so very fragile. there is a striking difference between the middle and upper chalk, which all will observe. it consists in the numerous bands of dark flints which run through the upper chalk parallel to the strata. the lower chalk is entirely, and the middle chalk nearly, devoid of flint. though the line at which the commencement of the upper chalk is taken is rather below the first flint band of the upper chalk, and a few flints occur in the highest beds of the middle chalk; yet, speaking generally, the great distinction between the middle and upper chalk, the two divisions of the white chalk, may be considered to be that of flintless chalk and chalk with flints. early in our studies we noticed the great curves into which the upheaved strata have been thrown, and that on the northern side of the anticline the strata are in places vertical. this can be well observed in the culver cliffs and brading down, where the strata of the upper chalk are marked by the lines of black flints. in the large quarry on brading down the vertical lines of flint can be clearly seen; and by walking at low tide at whitecliff bay round the corner of the cliff, or by observing the cliff from a boat, we may see a beautiful section of the flinty chalk, the lines of black flints sloping at a high angle. the flints in general form round or oval masses, but of irregular shape with many projections, and the masses lie in regular bands parallel to the stratification. the tremendous earth movement which has bent the strata into a great curve has compressed the vertical portion into about half its original thickness, and has made the chalk of our downs extremely hard. it has also shattered the flints in the chalk into fragments. the rounded masses retain their form, but when pulled out of the chalk fall into sharp angular fragments, and we find they are shattered through and through. [illustration: _photo by j. milman brown, shanklin._] culver cliffs--highly inclined chalk strata now, what are flints, and how were they formed? flints are a form of silica, a purer form than chert, as the chalk in which they are embedded was formed in the deep sea, and so we have no admixture of sand. flints, as we find them in the chalk, are generally black translucent nodules, with a white coating, the result of a chemical action which has affected the outside after they were formed. flint is very hard,--harder than steel. you cannot scratch it with a knife, though you may leave a streak of steel on the surface of the flint. this hardness is a property of other forms of silica, as quartz and chalcedony. the question how the flints were formed is a difficult one. as to this much still remains obscure. the sea contains mineral substances in solution. calcium sulphate and chloride, and a small amount of calcium carbonate (carbonate of lime) are in solution in the sea. from these salts is derived the calcium deposited as calcium carbonate to form the shells of the foraminifera and the larger shells in the chalk. there is also silica in small quantity in sea water. from this the skeletons of radiolaria and diatoms and the spicules of sponges are formed. now, many flints contain fossil sponges, and when broken show a section of the sponge clearly marked. especially well can this be seen in flints which have lain some time in a gravel bed formed of flints worn out of the chalk by denudation. hard as a flint seems, it is penetrated by numerous fine pores. the gravel beds are usually stained yellow by water containing iron, and this has penetrated by the pores through the substance of the flints, staining them brown and orange. many of the stained flints show beautifully the sponge markings,--a wide central canal with fine thread-like canals leading into it from all sides. the chalk sea evidently abounded in siliceous organisms, and it cannot be doubted that it is from such organisms that the silica was derived, which has formed the masses of flint. silica occurs in two forms--in a crystalline form as quartz or rock crystal, and as amorphous, _i.e._, formless or uncrystalline (also called opaline) silica. the siliceous skeletons of marine organisms are formed of amorphous silica. flint consists of innumerable fine crystalline grains, closely packed together. amorphous silica is less stable than crystalline, and is capable of being dissolved in alkaline water, _i.e._, water containing carbonate of sodium or potassium in solution. if the silica so dissolved be deposited again, it is generally in the crystalline form. it seems probable, therefore, that the amorphous silica of the skeletal parts of marine organisms has been dissolved by alkaline water percolating through the strata, and re-deposited as flint. as the silica was deposited, chalk was removed. the large irregular masses of flint lying in the chalk strata have clearly taken the place of chalk which has been removed. water charged with silica soaking through the strata has deposited silica, and at the same time dissolved out so much carbonate of lime. bivalve shells, originally carbonate of lime, are often replaced, and filled up by flint, and casts of sea urchins in solid flint are common, and often beautiful fossils. this process of change took place after the foraminiferal ooze had been compacted into chalk strata; and to some extent at any rate, there has been deposition of silica after the chalk had become hard and solid; for we find flat sheets, called tabular flint, lying along the strata, or filling cracks cutting through the strata at right angles. but in all probability the re-arrangement of the constituents of the strata took place in the main during the first consolidation, as the strata rose above the sea-level, and the sea-water drained out. a suggestion has been made by r. e. liesegang, of dresden, to explain the occurrence of the flints in the bands with clear interspaces between, which are such a marked feature of the upper chalk. he has shown how "a solution diffusing outward and encountering something with which it reacts and forms a precipitate, moves on into this medium until a concentration sufficient to cause precipitation of the particular salt occurs. a zone of precipitation is thus formed, through which the first solution penetrates until the conditions are repeated, and a second zone of precipitate is thrown down. zone after zone may thus arise as diffusion goes on." he suggests that the zones of flint may be similar phenomena, water diffusing through the masses of chalk taking up silica till such concentration is reached that precipitation takes place, the water then percolating further and repeating the process.[ ] the precipitation of silica and replacement of the chalk occurs irregularly along the zone of precipitation, forming great irregular masses of flint, which enclose the sponges and other marine organisms that lay in the chalk strata. where a deposit of silica has begun, it will probably have determined the precipitation of more silica, in the manner constantly seen in chemical precipitation; and it would seem that siliceous organisms as sponges have to some extent served as centres around which silica has been precipitated, for flints are very commonly found, having the evident external form of sponges. it will be well to say something here of the history of the flints as the chalk which contains them is gradually denuded away. rain water containing carbonic dioxide has a great effect in eating away all limestone rocks, chalk included. a vast extent of chalk, which formerly covered much of england has thus disappeared. the arch of chalk connecting our two ranges of downs has been cut through, and from the top of the downs themselves a great thickness of chalk has been removed. the chalk in the downs above ventnor and bonchurch is nearly horizontal. it consists of lower and middle chalk; and probably a small bit of the upper occurs. but the top of st. boniface down is covered with a great mass of angular flint gravel, which must have come from the upper chalk. the gravel is of considerable thickness, perhaps ft., and on the spurs of the down falls over to a lower level like a table-cloth. it is worked in many pits for road metal. this flint gravel represents the insoluble residue which has been left when the chalk was dissolved away. on the top of the cliffs between ventnor and bonchurch, at a point called highport, is a stratum of flint gravel carried down from the top of the down. the shore here is strewn with large flints fallen from the gravel. the substance of many of the flints has undergone a remarkable change. instead of black or dull grey flint it has become translucent agate, of splendid orange and purple colours, or has been changed into clear translucent chalcedony. in the agate the forms of fossil sponges can often be beautifully seen. the colours are due to iron-charged water percolating into the flint in the gravel bed, but further structural changes have altered the form of the silica; chalcedony having a structure of close crystalline fibres, revealed by polarized light: when variously stained and coloured, it is usually called agate. many of these flints, when cut through and polished, are of great beauty. the main force of the tides along these shores is from west to east; and so there is a continual passage of pebbles on the shore in that direction. the flints in sandown bay have in the main travelled round from here; and towards the culvers small handy specimens of agates and chalcedonies rounded by the waves may be collected. [illustration: _photo by j. milman brown, shanklin._] scratchell's bay--highly inclined chalk strata the extensive downs in the centre of the island are largely overspread with angular flint gravel similarly formed to that of st. boniface. of other beds of gravel, which have been washed down to a lower level by rivers or other agency we shall have more to say later. the chalk strata in the isle of wight are of great thickness. in the culver cliff there are some feet of flintless chalk (lower and middle chalk), and then some , feet of chalk with flints. there is some variation in the thickness of the strata in different parts of the island, and the amount of the upper strata, which has been removed by denudation, varies considerably. the average thickness of the white chalk in the island is about , feet.[ ] including the lower chalk, the maximum thickness of the chalk strata is , ft. the divisions of the chalk we have so far considered depend on the character of the rock: we must say a word about another way of dividing the strata. it is found that in the chalk, as in other strata, fossils change with every few feet of deposit. we may make a zoological division of the chalk by seeing how the fossils are distributed. the chalk was first studied from this point of view by the great french geologist, m. barrois, who divided it into zones, according to the nature of the animal life, the zones being called by the name of some fossil specially characteristic of a particular zone. more recently dr. a. w. rowe has made a very careful study of the zones of the white chalk, and is now our chief authority on the subject. the strata have been grouped into zones as follows:-- zones. sub-zones. { belemnitella mucronata. { actinocamax quadratus. { { offaster pilula. upper { offaster pilula. { echinocorys depressus. chalk. { { marsupites { marsupites. { testudinarius. { uintacrinus. { micraster cor-anguinum. { micraster cor-testudinarium. { holaster planus. middle { terebratulina lata. chalk. { inoceramus labiatus. { holaster subglobosus. { actinocamax lower { { plenus (at top). chalk. { schloenbachia varians.{ stauronema { { carteri (at base). the method of study according to zoological zones is of great interest. the period of the white chalk was of long duration, and the physical conditions remained very uniform. so that by studying the succession of life during this period we may learn much about the gradual change of life on the earth, and the evolution of living things. we have seen that the whole mass of the chalk is made up mainly of the remains of living things,--mostly of the microscopic foraminifera. we have seen that sponges were very plentiful in that ancient sea. of other fossils we find brachiopods--different species of terebratula and rhynchonella--a large bivalve _inoceramus_ sometimes very common; the very beautiful bivalve, _spondylus spinosus_, belemnites, serpulæ; and different species of sea-urchin are very common. a pretty heart-shaped one, _micraster cor-anguinum_, marks a zone of the higher chalk, which runs along the top of our northern downs. other common sea urchins are various species of _cidaris_, of a form like a turban (gk. _cidaris_, a persian head-dress); _cyphosoma_, another circular form; the oval _echinocorys scutatus_, which, with varieties of the same and allied species, abounds in the upper chalk, and the more conical _conulus conicus_. the topmost zone, that of _b. macronata_, would yield a record of exuberant life, were the chalk soft and horizontal. there was a rich development of echinoderms (sea urchins and star fishes), but nothing is perfect, owing to the hardness of the rock (dr. rowe). the general difference in the life of the chalk period is the great development of ammonites and other cephalopods in the lower chalk, and of sea urchins and other echinoderms in the upper, while the middle chalk is wanting in the one and the other. shark's teeth tell of the larger inhabitants of the ocean that flowed above the chalky bottom. many quarries have been opened on the flanks of the chalk downs, of which a large number are now disused. they occur just where they are needed for chalk to lay on the land, the pure chalk on the north of the downs to break up the heavy tertiary clays, which largely cover the north of the island; the more clayey beds of the grey chalk on the south of the downs to stiffen the light loams of the greensand.[ ] [footnote : see _common stones_, by grenville a. j. cole, f.r.s. .] [footnote : , ft. at the western end of the island, , ft. at the eastern.--dr. rowe's measurements.] [footnote : dr. a. w. rowe.] chapter viii the tertiary era: the eocene ages must have passed while the ocean flowed over this part of the world, and the chalk mud, with its varied remains of living things, gradually accumulated at the bottom. at last a change came. slowly the sea bed rose, till the chalk, now hardened by pressure, was raised into land above the sea level. as soon as this happened, sea waves and rain and rivers began to cut it down. there is evidence here of a wide gap in the succession of the strata. higher chalk strata, which probably once existed, have been washed away, while the underlying strata have been planed off to an even surface more or less oblique to the bedding-planes. the highest zone of the chalk in the island (that of _belemnitella macronata_) varies greatly in thickness, from ft. at the eastern end of the island to at the western. the latest investigations give reason to conclude that this is due to gentle synclines and anticlines, which have been planed smooth by the erosion which preceded the deposition of the next strata,--the eocene.[ ] at alum bay the eroded surface of the chalk may be seen with rolled flints lying upon it, and rounded hollows or pot-holes, the appearance being that of a foreshore worn in a horizontal ledge of rock, much like the horse ledge at shanklin. the land sank again, but not to anything like the depth of the great chalk sea. we now come to an era called the tertiary. the whole geological history is divided into four great eras. the first is the eozoic, or the age of the archæan,--often called pre-cambrian--rocks; rocks largely volcanic, or greatly altered since their formation, showing only obscure traces of the life which no doubt existed. then follow the primary era, or, as it is generally called, the palæozoic; the secondary or mesozoic; and the tertiary or kainozoic. palæozoic is used rather than primary, as this word is ambiguous, being also used for the crystalline rocks first formed by the solidification of the molten surface of the earth. but secondary and tertiary are still in constant use. these long ages, or eras, were of very unequal duration; yet they mark such changes in the life of animal and plant upon the earth that they form natural divisions. the palæozoic was an immense period during which life abounded in the seas,--numberless species of mollusca, crustaceans, corals, fish are found,--and there were great forests, which have formed the coal measures, on land,--forests of strange primeval vegetation, but in which beautiful ferns, large and small, flourished in great numbers. the secondary era may be called the age of reptiles. to this era all the rocks we have so far studied belong. now we come to the last era, the tertiary, the age of the mammals. instead of reptiles on land, in sea and air, we find a complete change. the earth is occupied by the mammalia; the air belongs to the birds such as we see to-day. the strange birds of the oolitic and cretaceous have passed away. birds have taken their modern form. in some parts of the world strata are found transitional between the secondary and tertiary. the tertiary is divided into four divisions,--the eocene, the oligocene (once called upper eocene), the miocene, and the pliocene; which words signify,--pliocene the more recent period, miocene the less recent, eocene the dawn of the recent. in the eocene we shall find marine deposits of a comparatively shallow sea, and beds deposited at the mouth of great rivers, where remains of sea creatures are mingled with those washed down from the land by the rivers. these strata run through the isle of wight from east to west, and we may study them at either end of the island, in whitecliff and alum bays. the strata are highly inclined, so that we can walk across them in a short walk. some beds contain many fossils, but many of the shells are very brittle and crumbly; and we can only secure good specimens by cutting out a piece of the clay or sand containing them, and transferring them carefully to boxes, to be carried home with equal care. often much of the face of the cliff is covered with slip or rainwash, and overgrown with vegetation. sometimes a large slip exposes a good hunting ground. now let us walk along the shore, and try to read the story these tertiary beds tell us. we will begin in whitecliff bay. though easily accessible, it remains still in its natural beauty. the sea washes in on a fine stretch of smooth sand sheltered by the white chalk wall which forms the south arm of the bay. north of the culver downs the cliffs are much lower, and consist of sands and clays of varying colour, following each other in vertical bands. looking along the line of shore we notice a band of limestone, at first nearly vertical like the preceding strata, then curving at a sharp angle as it slopes to the shore, and running out to sea in a reef known as bembridge ledge. this is the bembridge limestone; and the beginning of the reef marks the northern boundary of whitecliff bay, the shore, however, continuing in nearly the same line to bembridge foreland, and showing a continuous succession of eocene and oligocene strata. the strata north of the limestone are nearly horizontal, dipping slightly to the north. in the bembridge limestone we see the end of the sandown anticline, and the beginning of the succeeding syncline. the strata now dip under the solent, and rise into another anticline in the portsdown hills. north and south of the great anticline of the weald of kent and sussex are two synclinal troughs known as the london and hampshire basins. nearly the whole of our english eocene strata lies in these two basins, having been denuded away from the anticlinal arches. the oligocene only occur in the hampshire basin, the higher strata only in the isle of wight. [illustration: fig. .] coast section, whitecliff bay. bm _bembridge marls._ bl _bembridge limestone._ o _osborne beds._ h _headon beds._ bs _barton sand._ b _barton clay._ br _bracklesham beds._ bg _bagshot beds._ l _london clay._ r _reading beds._ ch _chalk._ p _pebble beds._ s _sandstone band._ above the chalk we come first to a thick red clay called plastic clay. it is much slipped, and the slip is overgrown. the only fossils found in the island are fragments of plants; larger plant remains on the mainland show a temperate climate. this clay was formerly worked at newport for pottery. the clay is probably a freshwater deposit formed in fairly deep water. on the mainland we find on the border shallow water deposits called the woolwich and reading beds. (the clay is to ft. thick at whitecliff bay, less than ft. at the alum bay.) we come next to a considerable thickness of dark clay with sand, at the surface turned brown by weathering. this is the london clay, so called because it underlies the area on which london is built. at the base is a band of rounded flint pebbles, which extends at the base of the clay from here to suffolk. in it, as well as in a hard sandstone inches higher up, are tubular shells of a marine worm, _ditrupa plana_. the sandstone runs out on the shore. about ft. above the basement bed is a zone of _panopæa intermedia_ and _pholadomya margaritacea_, at ft. another band of _ditrupa_, and at about ft. a band with a small _cardita_. in the higher part of the clay are large septaria,--rounded blocks of a calcareous clay-ironstone, with cracks running through them filled with spar. _pinna affinis_ is found in the septaria. the thickness of the clay in whitecliff bay is feet. it can be seen on the shore, when the tide happens to have swept the sand away. otherwise the lower beds are hardly visible, there being no cliff here, but a slope overgrown with vegetation. in alum bay the london clay, about ft. in thickness, consists of clays, chiefly dark blue, with sands, and lines of septaria. in the lower part is a dark clay with _pholadomya margaritacea_, still preserving the pearly nacre. there are also _panopæa intermedia_, and in septaria _pinna affinis_. all these with their pearly lustre, are beautiful fossils. a little higher is a zone with _ditrupa_, and further on a band of _cardita_. other shells also are found in the clay, especially in the lower part. they are all marine, and indicate a sub-tropical climate. lines of pebbles show that we are near a beach. in other parts of the south of england remains from the land are found, borne down an ancient river in the way we found before in the wealden deposits. but times have changed since the wealden days, and the life of the tertiary times has a much more modern appearance. from leaves and fruits borne down from the forest we can learn clearly the nature of the early eocene land and climate. leaves are found at newhaven, and numerous fossil fruits at sheppey. the character of the vegetation most resembled that now to be seen in india, south eastern asia, and australia. palms grew luxuriantly, the most abundant fruit being that of one called nipadites, from its resemblance to the nipa palm, which grows on the banks of rivers in india and the philippines. the forests also included plants allied to cypresses, banksia, maples, poplars, mimosa, custard apples, gourds, and melons. the rivers abounded in turtle--large numbers of remains of which are found in the london clay at the mouth of the thames--crocodiles and alligators. with the exception of the south east of england, all the british isles formed part of a continental mass of land covered with a tropical vegetation. the mountain chains of england, scotland, and wales rose as now, but higher. long denudation has worn them down since. in the south-east of england the coast line fluctuated; and sea shells, and the remains of the plant and animal life of the neighbourhood of a great tropical river alternate in the deposits. [illustration: fig. ] section through headon hill and high down. showing strata seen at alum bay. g _gravel cap._ bm _bembridge limestone._ o _osborne beds._ uh _upper headon._ mh _middle " ._ lh _lower headon._ bs _barton sand._ b _barton clay._ br _bracklesham beds._ bg _bagshot sands._ l _london clay._ r _reading beds._ ch _chalk._ the london clay is succeeded by a great thickness of sands and clays which form the bagshot series. these are divided in the london basin into lower, middle, and upper bagshot. in the hampshire basin the strata are now classified as bagshot sands, bracklesham beds, barton beds, the last comprising the barton clay and the barton sand, formerly termed headon hill sands. there is some uncertainty as to the manner in which these correspond to the beds of the bagshot district, as the tertiary strata have been divided by denudation into two groups, and differ in character in the two areas. it is possible that the barton sand represents a later deposit than any in the london area. almost the only fossil remains in the bagshot sands are those of plants, but these are of great interest. in whitecliff bay the beds consist for the most part of yellow sands, above which is a band of flint pebbles, which has been taken as the base of the bracklesham series, for in the clay immediately above marine shells occur. the bagshot sands, in whitecliff bay, are about feet thick, in alum bay, feet, according to the latest classification. in alum bay the strata consist of sands, yellow, grey, white, and crimson, with clays, and bands of pipe clay. this is remarkably white and pure, as though derived from white felspar, like the china clay in cornwall. the pipe clay contains leaves of trees, sometimes beautifully preserved. specimens are not very easy to obtain, as only the edges of the leaves appear at the surface of the cliff. they have been found chiefly in a pocket, or thickening of the seam of pipe clay, which for forty years yielded specimens abundantly, afterwards thinning out, when the leaves became rare. the leaves lie flat, as they drifted and settled down in a pool. with them are the twigs of a conifer, occasionally a fruit or flower, or the wing case of a beetle. the leaves show a tropical climate. the flora is a local one, differing considerably from those of eocene deposits elsewhere. the plants are nearly all dicotyledons. of palms there are only a few fragments, while the london clay of sheppey is rich in palm fruits, and many large palms are found in the bournemouth leaf beds, corresponding in date to the bracklesham. the differences may be largely due to conditions of locality and deposition. the alum bay flora is characterised by a wealth of leguminous plants, and large leaves of species of fig (_ficus_); simple laurel and willow-like leaves are common, of which it is difficult to determine the species, and there is abundance of a species of _aralia_. the character of the flora resembles most those of central america and the malay archipelago. [illustration: pl. iv] nummulites lævigatus turritella limnæa imbricataria longiscata cardita planicosta (fusus) planorbis leiostama pyrus euomphalus cyrena semistriata eocene and oligocene the bracklesham beds in alum bay ( ft. thick) consist of clays, with lignite forming bands in. to ft. thick; white, yellow, and crimson sands; and in the upper part dark sandy clays, with bands showing impressions of marine fossils. alum bay takes its name from the alum formerly manufactured from the tertiary clays. the coloured sands have made the bay famous. the colours of the sands when freshly exposed, and of the cliffs when wet with rain, are very rich and beautiful,--deep purple, crimson, yellow, white, and grey. some of the beds are finely striped in different shades by current bedding. the contrast of these coloured cliffs with the white chalk, weathered to a soft grey, of the other half of the bay is very striking and beautiful. about ft. from the top is a conglomerate of flint pebbles, some of large size, cemented by iron oxide. in whitecliff bay the bracklesham beds ( ft.) consist of clays, sands, and sandy clays, mostly dark, greenish and blue in colour, containing marine fossils and lignite. sir richard worsley, in his history of the isle of wight, tells that in february, , a bed of coal was laid bare in whitecliff bay, causing great excitement in the neighbourhood. people flocked to the shore for coal, but it proved worthless as fuel. it has, however, been worked to some extent in later years. in some of the beds are many fossils. numbers have lately been visible where a large founder has taken place. there are large shells of _cardita planicosta_ and _turritella imbricataria_. they are, however, very fragile. in a stratum just above these are numbers of a large nummulite (_nummulites lævigatus_). these are round flat shells like coins,--hence the name (lat. _nummus_, a coin). they are a large species of foraminifera. we may split them with a penknife; and then we see a pretty spiral of tiny chambers. a smaller variety, _n. variolarius_, occurs a little further on, and a tiny kind, _n. elegans_, in the barton clay. one of the most striking features of the later eocene is the immense development of nummulite limestones--vast beds built up of the delicate chambered shells of nummulites,--which extend from the alps and carpathians into thibet, and from morocco, algeria, and egypt, through afghanistan and the himalaya to china. the pyramids of egypt are built of this limestone. the bracklesham beds are followed by the barton clay, famous for the number of beautiful fossil shells found at barton on the hampshire coast. at whitecliff bay the fossils are, unfortunately, very friable. at alum bay the pathway to the shore is in a gully in the upper part of the barton clay. the strata consist of clays, sands, and sandy clays. the base of the beds is marked by the zone of _nummulites elegans_. numerous very pretty shells of the smaller barton types may be found, with fragments of larger ones; or a whole one may be found. owing to the cliff section cutting straight across the strata, which are nearly vertical, there is far less of the beds open to observation than at barton, which probably accounts for the list of fossils being much smaller. the shells are chiefly several species of _pleurotoma_, _rostellaria_, _fusus_, _voluta_, _turritella_, _natica_, a small bivalve _corbula pisum_, a tubular shell of a sand-boring mollusc _dentalium_, _ostroea_, _pecten_, _cardium_, _crassatella_. the fauna is like a blending of malayan and new zealand forms of marine life. throughout the eocene from the london clay onward the shells are such as abound in the warm sea south east of asia. similarly the plant remains take us into a tropic land, where fan palms and feather palms overshadowed the country, trees of the tropics mingling with trees we still find in more northern latitudes. the general character of the flora as of the shells was oriental and malayan; both being succeeded in later strata by a flora and fauna with greater analogy to that now existing in western north america. in alum bay the barton clay is suddenly succeeded by the very fine yellow and white sands which run along the western base of headon hill, the curve of the syncline bringing them round from a nearly vertical to an almost horizontal position. these are now known as the barton sand. they are ft. thick, the whole of the barton beds being ft. in alum bay, ft. in whitecliff. the sands were formerly extensively used for glass making. they are almost unfossiliferous. the passage from barton clay to the sands in whitecliff bay is more gradual. the sands here show some fine colouring which reminds us of the more celebrated sands of alum bay. [footnote : see memoir of geological survey of i. w. by h. j. osborne white, f.g.s. , p. .] chapter ix the oligocene we pass on to strata which used to be called upper eocene, but are now generally classified as a period by themselves, and called the oligocene. they are also known as the fluvio-marine series. large part was deposited in freshwater by rivers running into lagoons, or in the brackish water of estuaries, while at times the sea encroached, and beds of marine origin were laid down. the west of the island is much the best locality for the lower strata, those which take their name from headon hill between alum and totland bays. there are three divisions of the headon strata, marine beds in the middle coming between upper and lower beds formed in fresh and brackish water. light green clays are very characteristic of these beds, and at the west of the island thick freshwater limestones, which have died out before the strata re-appear in whitecliff bay. the strongest masses of limestone in headon hill belong to the upper division. the limestones are full of freshwater shells, nearly all the long spiral limnæa and the flat spiral disc of planorbis, perhaps the most abundant species being _l. longiscata_ and _p. euomphalus_. the limestones themselves are almost entirely the produce of a freshwater plant _chara_, which precipitates lime on its tissues, in the same manner as the sea weeds we call corallines. on the shore round the base of headon hill lie numerous blocks of limestone, the débris of strata fallen in confusion, in which are beautiful specimens of limnæa and planorbis. the shells, however, are very fragile. the marine beds of the middle headon are best seen in colwell bay, where a few yards north of how ledge they descend to the beach, and a cliff is seen formed of a thick bed of oysters, _ostrea velata_. the oysters occupy a hollow eroded in a sandy clay full of _cytherea incrassata_, from which the bed is known as the "venus" bed, the shell formerly being called _venus_, later _cytherea_, at present _meretrix_. the marine beds contain many drifted freshwater shells as limnæa and cyrena. the how ledge limestone forms the top of the lower headon. it is full of well-preserved limnæa and planorbis. the upper and lower headon are mainly fresh or brackish water deposits. the purely freshwater beds contain _limnæa_, _planorbis_, _paludina_, _unio_, and land-shells. in the brackish are found _potamomya_, _cyrena_, _cerithium_ (_potamides_), _melania_ and _melanopsis_. _paludina lenta_ is very abundant throughout the oligocene. a large number of the marine shells of the headon beds are species also found in the barton clay. _cytherea_, _voluta_, _ancillaria_, _pleurotoma_, _natica_ are purely marine genera. in white cliff bay the beds are mostly estuarine. most of the fossils are found in two bands, one about ft. above the base of the series, the other a stiff blue clay, about feet higher, which seems to correspond with the "venus bed" of colwell bay. many of the fossils are of barton types. the headon beds are about feet thick at headon hill, ft. in whitecliff bay; and are followed by beds varying from about to ft. in thickness, known as the osborne and st. helens series. they consist mainly of marls variously coloured, with sandstone and limestone. in headon hill is a thick concretionary limestone, which almost disappears northward. the oligocene strata often vary considerably within short distances. the osborne beds are exposed along the low shore between cowes and ryde, and from sea view to st. helens. in whitecliff bay they are not well seen, occurring in overgrown slopes. they consist mostly of red and green clays. a band of cream-yellow limestone a foot thick is the most conspicuous feature. the fossils resemble those from the headon beds, but are much less plentiful. the marls seem to have been mostly deposited in lagoons of brackish water, which at the present day are favourite places for turtles and alligators, and of these many remains are found in the osborne beds. the beds are specially noted for the shoals of small fish, _diplomystus vectensis_ (_clupea_), first observed by mr. g. w. colenutt, f.g.s., and prawns found in them, and also remains of plants. the beds that appear in the neighbourhood of sea view and st. helens are divided into nettlestone grits and st. helen's sands, the former containing a freestone feet thick. above these beds lies the bembridge limestone, which is so conspicuous in whitecliff bay, and forms bembridge ledge. on the north shore of the island the strata rise slightly on the northern side of the syncline. there are also minor undulations in an east and west direction. the result is to bring up the bembridge limestone at various points along the north shore, where it forms conspicuous ledges--hamstead ledge at the mouth of the newtown river, ledges in thorness bay, and gurnard ledge. in whitecliff bay the limestone, about feet thick, forms the conspicuous reef called bembridge ledge. the bembridge limestone consists of two or more bands of limestone with intercalated clays. it is usually whiter than the headon limestones, and the fossils occur as casts, the shells being sometimes replaced by calc-spar. the limestone has been much used as a building stone for centuries, not only in the island, but for buildings on the mainland. the most famous quarries were those near binstead, from which quarr, the site of the great abbey, now almost entirely disappeared, derives its name. from these quarries was obtained much of the stone for winchester cathedral and many other ancient buildings. in the old walls and buildings of southampton the stone may be recognised at once by the casts of the limnæae it contains. the quarries at quarr were noted in more ways than one. in later times the remains of early mammalia,--palæotherium, anoplotherium, and others--have been found. the quarries are now abandoned and overgrown. the limestone may be seen inland at brading, where it forms the ridge on which the church stands. the limestone is a freshwater formation, and the fossils are mostly freshwater shells, of the same type as the headon, limnæa and planorbis the most common. there are also land shells, especially several species of helix, the genus which includes the common snail,--_h. globosa_, very large,--and great species of _bulimus_ (_amphidromus_) and _achatina_ (_b. ellipticus_, _a. costellata_). these interesting shells were chiefly obtained in the limestone at sconce near yarmouth, a locality now inaccessible, being occupied by fortifications. the land shells have an affinity to species now found in southern north america. the limestone also abounds in the so-called "seeds" of chara. the reproductive organs,--the "seeds,"--of this curious water-plant, allied to the lower algæ, are, like the rest of the plant, encased in carbonate of lime, and are very durable. large numbers are found in the oligocene strata. under the microscope they are seen to be beautifully sculptured in various designs, with a delicate spiral running round them. above the limestone lie the bembridge marls, varying in thickness in different localities from to feet. north of whitecliff bay they stretch on to the foreland. they are in the main a freshwater formation, but a few feet above the limestone is a marine band with oysters, _ostrea vectensis_. it runs out along the shore, where the oysters may be seen covering the surface. the lower marls consist chiefly of variously-coloured clays with many shells, chiefly _cyrena pulchra_, _semistriata_, and _obovata_, _cerithium mutabile_, and _melania muricata_ (_acuta_); and red and green marls, in which are few shells, but fragments of turtle occur. a little above the oyster bed is a band of hard-bluish septarian limestone. sixty years ago edward forbes remarked on the resemblance of this band to the harder insect-bearing limestones of the purbeck beds. in a limestone exactly resembling this, and similarly situated in the lower part of the marls in gurnard and thorness bays, numerous insects were afterwards found,--beetles, flies, locusts, and dragonflies, and spiders. leaves of plants, including palms, fig, and cinnamon, have also been found in this bed, showing that the climate was still sub-tropical. the upper marls consist chiefly of grey clays with abundance of _melania turritissima_ (_potamaclis_). the chief shells in the marls are _cyrena_, _melania_, _melanopsis_ and _paludina_ (_viviparus_). they are often beautifully preserved; the species of cyrena often retain their colour-markings. bembridge foreland is formed by a thick bed of flint gravel resting on the marls, which are seen again in priory bay, where in winter they flow over the sea-wall in a semi-liquid condition. they lie above the limestone at gurnard, thorness, and hamstead. west of hamstead ledge the whole of the beds crop out on the shore, where beautifully preserved fossils may be collected. large pieces of drift wood occur, also seeds and fruit. many fragments of turtle plates may be found. large crystals of selenite (sulphate of lime) occur in the marls. last of the oligocene in the isle of wight are the hamstead beds. these strata are peculiar to the isle of wight. the bembridge beds also are not found on the mainland, except a small outlier at creechbarrow hill in dorset. the hamstead beds consist of some feet of marls, in which many interesting fossils have been found. they cover a large area of the northern part of the island, largely overlaid by gravels, and are only seen on the coast at hamstead, where they form the greater part of the cliff, which reaches a height of ft., the top being capped by gravel. in winter the clays become semi-liquid, in summer the surface may be largely slip and rainwash, baked hard by the sun. the lower part of the strata may be best seen on the shore. the strata consist of ft. of freshwater, estuarine, and lagoon beds, with _unio_, _cyrena_, _cyclas_, _paludina_, _hydrobia_, _melania_, _planorbis_, _cerithium_ (rare), and remains of turtles, crocodiles, and mammals, leaves and seeds of plants; and above these beds feet of marine beds with _corbula_, _cytherea_, _ostrea callifera_, _cuma_, _voluta_, _natica_, _cerithium_, and _melania_. except for the convenience of dividing so large a mass of strata, it would not be necessary to divide these from the bembridge beds, as no break in the character of the life of the period occurs at the junction. the basement bed of the hamstead strata is known as the black band, feet of clay, coloured black with vegetable matter, with _paludina lenta_ very numerous, _melanopsis carinata_, _limnæa_, _planorbis_, a small _cyclas_ (_c. bristovii_), seed vessels, and lumps of lignite. it rests on dark green marls with _paludina lenta_ and _melanopsis_, and full of roots. this evidently marks an old land surface. about feet higher is the white band,--a white and green clay full of shells, mostly broken. there are bands of tabular ironstone containing _paludina lenta_. clay ironstone was formerly collected on the shore between yarmouth and hamstead and sent to swansea to be smelted. the strata consist largely of mottled green and red clays, probably deposited in brackish lagoons. these yield few fossils except remains of turtle and crocodile and drifted plants. the blue clays are much more fossiliferous. among other plants are leaves of palm and water-lily. the strata gradually become more marine upwards. the marine beds were called by forbes the corbula beds, from two small shells, _c. pisum_ and _c. vectensis_, of which some of the clays are full. remains of early mammalia are found in the hamstead beds, the most frequent being a hog-like animal, of supposed aquatic habits, hyopotamus, of which there are more than one species. the fauna and flora of the oligocene strata show that the climate was still sub-tropical, though somewhat cooling down from the eocene. palms grew in what is now the isle of wight. alligators and crocodiles swam in the rivers. turtle were abundant in river and lagoon. specially interesting in the eocene and oligocene are the mammalian remains. they show us mammals in an early stage before they branched off into the various families as we know them to-day. the palæotherium was an animal like the tapir, now an inhabitant of the warmer regions of asia and america. recent discoveries in eocene strata in egypt show stages of development between a tapir-like animal and the elephant with long trunk and tusks. there were in those days hog-like animals intermediate between the hogs and the hippopotami. there were ancestors of the horse with three toes on each foot. there were hornless ancestors of the deer and antelopes. many of the early mammals showed characters now found in the marsupials, the order to which the kangaroo and opossum belong, members of which are found in rocks of the secondary era, and are the only representatives of the mammalia in that age. some of the early eocene mammalia are either marsupials, or closely related to them. in the oligocene we find the mammalian life becoming more varied, and branching out into the various groups we know to-day; while the succeeding miocene period witnesses the culmination of the mammalia--mammals of every family abounding all over the earth's surface, in a profusion and variety not seen before--or since, outside the tropics. chapter x before and after.--the ice age. we have read the story written in the rocks of the isle of wight. what wonderful changes we have seen in the course of the long history! first we were taken back to the ancient wealden river, and saw in imagination the great continent through which it flowed, and the strange creatures that lived in the old land. we saw the delta sink beneath the sea, and a great thickness of shallow water deposits laid down, enclosing remains of ammonites and other beautiful forms of life. then long ages passed away, while in the waters of a deeper sea the great thickness of the chalk was built up, mainly by the accumulation of microscopic shells. in time the sea bed rose, and new land appeared, and another river bore down fruits to be buried with sea shells and remains of turtles and crocodiles in the mud deposited near its mouth to form the london clay. we followed the alternations of sea and land, and the changing life of eocene and oligocene times. we have heard of the early mammalia found in the quarries of quarr, and have learnt from the leaf beds of alum bay that at that time the climate of this part of the world was tropical. indeed, i think everything goes to prove that through the whole of the times we have been studying,--except perhaps the earliest eocene, that of the reading beds,--the climate was considerably warmer than it is at the present day. after all these changes do you not want to know what happened next? well, at this point we come to a gap in the records of the rocks, not only in the isle of wight, but also in the british isles. the british isles, or even england and wales alone, are almost, if not quite unique in the world in that, in their small extent, they contain specimens of nearly every formation from the most ancient times to the present day. in other parts of the world we may find regions many times this area, where we can only study the rocks of some one period. but just at this point in the story comes a period,--a very important one, too,--the miocene--of which we have no remains in our islands. we must hear a little of what happened before we come back to the isle of wight again in comparatively recent times. but, first, perhaps, i had better tell,--just in outline,--something of the earlier history of the world, before any of our isle of wight rocks were made. for, if i do not, quite a wrong idea may be formed of the world's history. the time of the wealden river has seemed to us very ancient. we cannot say how many hundreds of thousands, or rather millions of years have passed since that ancient wealden age. and you may have thought that we had got back then very near the world's birthday, and were looking at some of the oldest rocks on the globe. but no. we are not near the beginning yet. compared with the vast ages that went before, our wealden period is almost modern. we cannot tell with any certainty the comparative time; but we may compare the thickness of strata formed to give us some sort of idea. now to the first strata in which fossil remains of living things are found we have in all a thickness of strata some times that of all the rocks we have been studying from wealden to oligocene, together with the later rocks, miocene and pliocene, not found in the isle of wight. and before that there is, perhaps, an equal thickness of sedimentary deposits; though the fossils they, no doubt, once contained have been destroyed by changes the rocks have undergone. now let me try to give you some idea of the world's history up to the point where we began in the isle of wight. if we could see back through the ages to the furthest past of geological history, we should see our world,--before any of the stratified rocks were laid down in the seas,--before the seas themselves were made,--a hot globe, molten at least at the surface. how do we know this? because under the rocks of all the world's surface we find there is granite or some similar rock,--a rock which shows by its composition that it has crystallised from a molten condition. moreover we have seen that the interior of the earth is intensely hot. and yet all along the earth must be radiating off heat into the cold depths of space, and cooling like any other hot body surrounded by space cooler than itself. and this has gone on for untold ages. far enough back we must come to a time when the earth was red hot,--white hot. in imagination we see it cooling,--the molten mass solidifies into igneous rock,--the clouds of steam in which the globe is wrapped condense in oceans upon the surface. the bands of crystalline rock that rise above the primeval seas are gradually worn down by rain and rivers and waves, and the first sedimentary deposits laid down in the waters. and in the waters and on the land life appeared for the first time,--we know not how. a vast thickness of stratified rocks was formed, which are called archæan ("ancient"). they represent a time, perhaps, as great as all that has followed. these rocks have undergone great changes since their formation. they have been pressed under masses of overlying strata, and have come into the neighbourhood of the heated interior of the earth; they have been burnt and baked and compressed and folded, and acted on by heated water and steam, and their whole structure altered by heat and chemical action. limestones, _e.g._, have become marble, with a crystalline structure which has obliterated any fossils they may have once contained. yet it is probable that, like nearly all later limestones, they are of organic origin. these archæan rocks cover a large extent of country in canada. we have some of them in our islands, in the hebrides, and north-west of scotland and in anglesey, and rising from beneath later rocks in the malvern hills and charnwood forest.[ ] the archæan rocks are succeeded by the most ancient fossiliferous rocks, the great series called the cambrian, because found, and first studied, in wales. they consist of very hard rocks, and contain large quantities of slate. they are followed by another series called the ordovician; and that by another the silurian. these three great systems of rocks measure in all some , ft. of strata. they form the hills of wales and the english lake district. they contain large masses of volcanic rocks. we can see where were the necks of old volcanoes, and the sheets of lava which flowed from them. the volcanoes are worn down to their bases now; and the hills of wales and the lakes represent the remains of ancient mountain chains, which rose high like the alps in days of old, long before alps or himalayas began to be made. these ancient rocks contain abundant remains of living things, chiefly mollusca, crustaceans, corals, and other marine organisms, showing that the waters of those ages abounded with life. we must pass on. next comes a period called the devonian, or old red sandstone, when the old red rocks of devon and scotland were laid down. these contain remains of many varieties of very remarkable fish. a long period of coral seas succeeded, when coral reefs flourished over what was to be england; and their remains formed the carboniferous limestone of derbyshire and the mendip hills. a period followed of immense duration, when over pretty well the whole earth there seem to have been comparatively low lands covered with a luxuriant and very strange vegetation. the remains of these ancient forests have formed the coal measures, which tell of the most widespread and longest enduring growth of vegetation the world has seen. strange as some of the plants were--gigantic horsetails and club-mosses growing into trees--many were exquisitely beautiful. there were no flowering plants, but the ferns, many of them tree ferns, were of as delicate beauty as those of the present day. many of the ferns bore seeds, and were not reproduced by spores, such as we see on the fronds of our present ferns. that is a wonderful story of plant history, which has only been read in recent years. after the long carboniferous period came to an end followed periods in which great formations of red sandstone were made,--the permian, and the new red sandstone or trias. during much of this time the condition of the country seems to have resembled that of the steppes of central asia, or even the great desert of sahara--great dry sandy deserts--hills of bare rock with screes of broken fragments heaped up at their base,--salt inland lakes, depositing, as the effect of intense evaporation, the beds of rock salt we find in cheshire or elsewhere, in the same manner as is taking place to-day in the caspian sea, in the salt lakes of the northern edge of the sahara, and in the great salt lake of utah. at the close of the period the land here sank beneath the sea--again a sea of coral islands like the south pacific of to-day. there were many oscillations of level, or changes of currents; and bands of clay, when mud from the land was laid down, alternate with beds of limestone formed in the clearer coral seas. these strata form a period known as the jurassic, from the large development of the rocks in the jura mountains. in england the period includes the liassic and oolitic epochs. the liassic strata stretch across england from lyme regis in dorset to whitby in yorkshire. most of the strata we are describing run across england from south-west to north-east. after they were laid down a movement of elevation, connected with the movement which raised the alps in europe, took place along the lines of the welsh and scotch mountains and the chain of scandinavia, which raised the various strata, and left them dipping to the south-east. worn down by denudation the edges are now exposed in lines running south-west to north-east, while the strata dip south-east under the edges of the more recent strata. the lias is noted for its ammonites, and especially for its great marine reptiles, ichthyosaurus and plesiosaurus. the oolitic epoch follows--a long period during which the fine limestone, the bath freestone, was made; the limestones of the cotswolds, beds of clay known as the oxford and kimmeridge clays; and again coral reefs left the rock known as coral rag. in the later part of the period were formed the portland and purbeck beds, marine and freshwater limestones, which contain also an old land surface, which has left silicified trunks of trees and stems of cycads. and now following on these came our wealden strata, the beginning of the cretaceous period. you see what ages and ages had gone before, and that when wealden times came, far back as they are, the world's history was comparatively approaching modern times. we must remember that all these formations, of which we have given a rapid sketch, are of great thickness,--thousands of feet of rock,--and represent vast ages of time. see what we have got to from looking at the shells in the sea cliff! we have come to learn something of the world's old history. we have been carried back through ages that pass our imagination to the world's beginning, to the time of the molten globe, before ever it was cool enough to allow life--we know not how--to begin upon its surface. and astronomy will take us back into an even more distant past, and show us a nebulous mist of vast extent stretching out into space like the nebulæ observed in the heavens to-day, before sun and planets and moons were yet formed. so we are carried into the infinite of time and space, and questions arise beyond the power of human mind to solve. now we have, i hope, a better idea of the position the strata we have been specially studying occupy in the geological history, and shall understand the relation the strata we may find elsewhere bear to those in the isle of wight and the neighbouring south of england. after this sketch of what went before our island story, we must see what followed at the end of the oligocene period. we said that there are no strata in the british isles representing the next period, the miocene. but it was a period of great importance in the world's history. great stratified deposits were laid down in france and switzerland and elsewhere, and it was a great age of mountain building. the alps and the himalaya, largely composed of cretaceous and eocene rocks, were upheaved into great mountain ranges. it is probable that during much of the period the british isles were dry land, and that great denudation of the land took place. but in the first part of the period at all events this part of the world must have been under water, and strata have been laid down, which have since been denuded away. for our soft oligocene strata, if exposed to rain and river action during the long miocene period and the time which followed, would surely have been entirely swept away. the miocene was succeeded by the pliocene, when the strata called the crag, which cover the surface of norfolk and suffolk, were formed. they are marine deposits with sea shells, of which a considerable proportion of species still survive. we have seen that through the ages we have been studying the climate was mostly warmer than at the present day. the climate of the eocene was tropical. the miocene was sub-tropical and becoming cooler. palms become rarer in the upper strata. evergreens, which form three-fourths of the flora in the lower miocene, divide the flora with deciduous trees in the upper. and through the pliocene the climate, though still warmer than now, was steadily becoming cooler; till in the beginning of the next period, the pleistocene, it had become considerably colder than that of the present day. and then followed a time which is known as the great ice age, or the glacial period,--a time which has left its traces all over this country, and, indeed all over northern europe and america, and even into southern lands. the cold increased, heavy snowfalls piled up snow on the mountains of wales, the lake district, and scotland; and the snow remained, and did not melt, and more fell and pressed the lower snow into ice, which flowed down the valleys in glaciers, as in switzerland to-day. gradually all the vegetation of temperate lands disappeared, till only the dwarf arctic birch and arctic willows were to be seen. the sea shells of temperate climates were replaced by northern species. animals of warm and temperate climates wandered south, and the arctic fox, and the norwegian lemming, and the musk ox which now lives in the far north of america took their place; and the mammoth, an extinct elephant fitted by a thick coat of hair and wool for living in cold countries, and a woolly-haired rhinoceros, and other animals of arctic regions occupied the land. when the cold was greatest, the glaciers met and formed an ice-sheet; and scotland, northern england and the midlands, wales, and ireland were buried in one vast sheet of ice as greenland is to-day. how do we know this? to tell how the story has been read would be to tell one of the most interesting stories of geology. here we can only give the briefest sketch of this wonderful chapter of the world's history. but we must know a little of how the story has been made out. we have already seen that the changes in plant and animal life point to a change from a hot climate, through a temperate, at last to arctic cold. again, over the greater part of northern england the rocks of the various geological periods are buried under sheets of tough clay, called boulder clay, for it is studded with boulders large and small, like raisins in a plum pudding. no flowing water forms such a deposit, but it is found to be just like the mass of clay with stones under the great glaciers and ice sheets of arctic regions; and just such a boulder clay may be seen extending from the lower end of glaciers in spitzbergen, when the glacier has temporarily retreated in a succession of warm summers. the stones in our boulder clay are polished and scratched in a way glaciers are known to polish and scratch the stones they carry along, and rub against the rocks and other stones. the rock over which the glacier moves is similarly scratched and polished, and just such scratching and polishing is found on the rocks in wales and the lake district. again, we find rocks carried over hill and dale and right across valleys, it may be half across england. we can trace for great distances the lines of fragments of some peculiar rock, as the granite of shap in westmorland; and even rocks from norway have been carried across the north sea, and left in east anglia. this will just give an idea how we know of this strange chapter in the history of our land. for, by this time it was our land--england--much as we know it to-day; though at times the whole stood higher above sea level, so that the beds of the channel and the north sea were dry land. but, apart from variation of level, the geography was in the main as now. [illustration: fig. ] shingle at foreland bm _bembridge marls._ s _shingle._ b _brick earth._ cf _old cliff in marls._ [illustration: fig. ] diagram of strata between southern downs and st. george's down. dotted lines _former extension of strata._ broken line _former bed of valley sloping to st. george's down._ the ice sheet did not come further south than the thames valley. what was the country like south of this? well, you must think of the land just outside the ice sheet in greenland, or other arctic country. no doubt the winters must have been very severe,--hard frosts and heavy snows,--the ground frozen deep. some arctic animals would manage to live as they do now just outside the ice sheet in greenland. now, have we any deposits formed at that time in the isle of wight? i think we have. a large part of the surface of the island is covered by sheets of flint gravel. the gravels differ in age and mode of formation. we have already considered the angular gravels of the chalk downs, composed of flints which have accumulated as the chalk which once contained them was dissolved away. but there are other gravel beds, which consist of flints which, after they were set free by the dissolution of the chalk, have been carried down to a lower level by rivers or other agency, and more or less rounded in the process. many of these beds occur at a high level; and, as they usually cap flat-topped hills, they are known as plateau gravels. perhaps the most remarkable is the immense sheet of gravel which covers the flat top of st. george's down between arreton and newport. gravel pits show upwards of feet of gravel, consisting of flints with some chert and ironstone, and the greatest thickness is probably considerably more than this. the southern edge of the sheet is cut off straight like a wall. to the north it runs out on ridges between combes which have cut into it. in places in the mass of flints occur beds of sand, which have all the appearance of having been laid down by currents of water. the base of the gravel where it is seen on the steep southern slope of the down has been cemented by water containing iron into a solid conglomerate rock. the flints forming this gravel have not simply sunk down from chalk strata dissolved away; for they lie on the upturned edges of strata from lower greensand to upper chalk, which have been planed off, and worn into a surface sloping gently to the north; and over this surface the gravel has somehow flowed. the sharp wall in which it ends at the upper part of the slope shows that it once extended to the south over ground since worn away. clearly, the gravel was formed before denudation had cut out the great gap between the central and southern downs of the island. the down where the gravel lies is ft. above sea level, ft. above the bottom of the valley below. so that, though the gravel sheet is much newer than the strata we have been studying, it must nevertheless be of great antiquity. it seems that at the top of st. george's down we are standing on what was once the floor of an old valley. in the course of denudation the bottom of a river valley often becomes the highest part of a district. for the bed of the valley is covered by flint gravel, and flint is excessively hard, and the bed of flints protects the underlying rock; so that, while the rocks on each side are worn away, what was the river bed is eventually left high above them. thus the highest points of a district are often capped by flint gravel marking the beds of old streams. tracing up this old valley to the southward, at a few miles distance it will have reached the chalk region on the south of the anticline: and the flints carried down the valley may have come from beds of angular flints already dissolved out of the chalk such as we find on st. boniface down. but how have these great masses of flints been swept along? can the land have been down under the sea; and have sea waves washed the stones along? but these flints, though water-worn, are not rounded as we find beach shingle. what immense rush of water can have spread these flints feet deep along a river valley? we must go to mountain regions for torrents of this character. and then, mountain torrents round the stones in their bed while these are mostly angular. the history of these gravels is a difficult one. i can only give what seems to me the most probable explanation. it appears to me probable that in the ice age, south of the ice sheet, the ground must have been both broken up by frosts, and also held together by being frozen hard to some depth. then when thaws came in the short but warm summers, or when an intermission of the severe cold took place, great floods would flow down the valleys in the country south of the ice sheet, and masses of ice with frozen earth and stones would be borne along in a sort of semi-liquid flow. in this way mr. clement reid explains the mass of broken-up chalk with large stones found on the heads of cliffs on the south coast, and known by the name of "combe-rock" or "head." the ice age was not one simple period, and it is still difficult to fit together the history we read in different places, and in particular to correlate the gravels of the south of england with the boulder clays of the glaciated area. there were certainly breaks in the period, during which the climate became much milder, or even warm; and these were long enough for southern species of animals and plants to migrate northward, and occupy the lands where an arctic climate had prevailed. there were moreover considerable variations in the relative level of land and sea. so that we have a very complex history, which is gradually coming into clearer light. that the gravels of the south of england belong largely to the age of ice, is shown by remains of the mammoth contained in many. these, however, are found in later gravels than those we have considered so far, gravels laid down after the land had been cut down to much lower levels. these lower gravels are known as valley gravels, because they lie along the course of existing valleys, the plateau gravels having been laid down before the present valleys came into existence. teeth of the mammoth are found in the thames valley, and on the shores of southampton water, in gravels about to feet above sea level, and have been found also in the isle of wight at freshwater gate, at the top of the cliffs near brook, and in other places. the gravels near brook with the clays on which they rest have been contorted, and the gravel forced into pockets in the clay, in a manner that suggests the action of grounding ice ploughing into the soil. the high level gravels must belong to an early stage of the glacial epoch. we get some idea of the great length of time this age must have lasted, as we look from st. george's down over the lower country of the centre of the island. after the formation of the st. george's down gravel the vast mass of strata between this and the opposite downs of st. boniface and st. catherine's was removed by denudation; and gravels were then laid down on the lower land, along blake down, at arreton, over hale common, and along the course of the yar. patches of gravel occur on the sandown and shanklin cliffs. at little stairs a gravel, largely of angular chert, reaches a thickness of feet, and in parts are several feet of loam above gravel. at the west of the island a great sheet of gravel covers the top of headon hill, reaching a height of feet. it appears sometimes to measure feet in thickness. like that on st. george's down it slopes towards the solent, resting on an eroded surface, in this case of tertiary strata; and here too the upper part of the sheet has been removed by the wearing out of the deep valley between the hill and the freshwater downs. the sheet lies on an old valley bottom, which sloped from the chalk downs on the south, then much higher and more extensive than now. here too we may see something of the length of the glacial period. for at freshwater gate is a much later gravel, in which teeth of the mammoth have been found. it was probably derived from older gravels that once lay to the south, as the flints are rounded by transport. but the formation of all these gravels appears to belong to the glacial period; and as we stand in freshwater gate, and look at this great gap in the downs worn out by the western yar, and think of the time when a river valley passed over the tops of the high downs and headon hill, we receive a strong impression of the length of the great ice age. now surely the question will be asked, what caused these changes of climate in the world's past history--so that at times a tropical vegetation spread over this land, and vegetation flourished sufficient to leave beds of coal within the arctic circle, and in the antarctic continent, and at another the climate of greenland came down to england, and an ice sheet covered nearly the whole country? this still remains one of the difficult problems of geology. an explanation has been attempted by astronomical theory, according to which the varying eccentricity of the earth's orbit--that is to say a slight change in the elliptic orbit of the earth, by which at times it becomes less nearly circular--a change which is known to take place--may have had the effect of producing these variations of climatic conditions. the theory is very alluring, for if this be the cause, we can calculate mathematically the date and duration of the glacial period. but, unfortunately, supposing the astronomical phenomena to have the effect required, the course of events given by the astronomical theory would be entirely different to that revealed by geological research. geographical explanations have usually failed through being of too local a character to explain a phenomenon which affected the whole northern hemisphere, and the effects of which reached at least as far south as the equator,[ ] and are seen again in the southern hemisphere in australia, new zealand, and south america. it is now believed that great world-movements take place, due to the contraction by cooling of the earth's interior, and the adjustment of the crust to the shrinkage.[ ] possibly some explanation might be found in these world-wide movements; but their effect seems to last through too long periods of time to suit our ice ages. again, while the geographical distribution of animals and plants in the present and past seems to imply very great changes in the land masses and oceanic areas,[ ] these changes appear to bear no relation to glacial epochs. the cause of the ice ages remains at present an unsolved problem. more than one ice age has occurred during the long geological history. the marks of such a period are found in archæan rocks, in the cambrian, when glaciers flowed down to the sea level in china and south australia within a few degrees of the tropics, and above all in early permian times. the dwyka conglomerate of the karroo formation of south africa (deposits of permo-carboniferous age) show evidence of extensive glaciation; deposits of the same age in northern and central india, even within the tropics, a glacial series of great thickness in australia, and deposits in brazil, appear to show a glaciation greater than that of the recent glacial period. yet these epochs formed only episodes in the great geological eras. on the whole the climate throughout geological time would seem to have been warmer than at the present day. it may, perhaps, be doubted whether the earth has yet recovered what we may call its _normal_ temperature since the glacial epoch. note on astronomical theory.--if the ice age be due to the increased eccentricity of the earth's orbit, the theory shows that a long duration of normal temperature will be followed by a group of glacial periods alternating between the northern and southern hemispheres, the time elapsing between the culmination of such a period in one hemisphere and in the other being about , years. while one hemisphere is in a glacial period, the other will be enjoying a specially mild,--a "genial" period. now, according to the record of the rocks, the "genial" periods were far from being those breaks in the glacial which we know as inter-glacial periods. we have the immensely long warm period of the eocene and oligocene, the miocene with a still warm but reduced temperature, and then the gradual cooling during the pliocene, till the drop in temperature culminates in the ice age. moreover, the duration of each glaciation during this ice age is usually considered to have been much longer than the , years or so given by the astronomical theory. add to this that the periods of high eccentricity of the earth's orbit, though occurring at irregular intervals, are, on the scale of geological time, pretty frequent; so that several of such periods would have occurred during the eocene alone. yet the geological evidence shows unbroken sub-tropical conditions in this part of the world throughout the eocene. [footnote : the older division of the archæan rocks--the lewisian gneisse--consists entirely of metamorphic and igneous rocks; a later division--the torridonian sandstones--is comparatively little altered, but still unfossiliferous.] [footnote : the great equatorial mountains kilimanjaro and ruwenzori show signs of a former extension of glaciers.] [footnote : for an account of such movements, see prof. gregory's _making of the earth_ in the home university library.] [footnote : see the _wanderings of animals_. by h. gadow, f.r.s., cambridge manuals.] chapter xi the story of the island rivers; and how the isle of wight became an island we must now consider the history of the river system of the isle of wight, to which our study of the gravels has brought us. for rivers have a history, sometimes a most interesting one, which carries us back far into the past. even the little rivers of the isle of wight may be truly called ancient rivers. for though recent in comparison with the ages of geological time, they are of a vast antiquity compared with the historical periods of human history. to understand our river systems we must go back to the time when strata formed by deposit of sediment in the sea were upheaved above the sea level. to take the simplest case, that of a single anticlinal axis fading off gradually at each end, we shall have a sort of turtle back of land emerged from the sea, as in figure , _aa_ being the anticlinal axis. from this ridge streams will run down on either side in the direction of the dip, their course being determined by some minor folds of the strata, or difference of hardness in the surface, or cracks formed during elevation. on each side of the dip-streams smaller ones will flow, more or less in the direction of the strike, and run into the main streams. various irregularities, such as started the flow of the streams, will favour one or another. consider three streams, _a_, _b_, _c_, and let us suppose the middle one the strongest, with greatest flow of water, and cutting down its bed most rapidly. its side streams will become steeper and have more erosive force, and so will eat back their courses most rapidly until they strike the line of the streams on either side. their steeper channels will then offer the best way for the upper waters of the streams they have cut to reach the sea; and these streams will consequently be tapped, and their head waters cut off to flow to the channel of the centre stream. we shall thus have for a second stage in the history a system such as is shown in fig. . the same process will continue till one river has tapped several others; and there will result the usual figure of a river and its tributaries, to which we are accustomed on our maps. we shall observe that tributaries do not as a rule gradually approach the central stream, but suddenly turn off at nearly a right angle from the direction in which they are flowing, and, after a longer or shorter course, join at another sharp angle a river flowing more or less parallel to their original direction. [illustration: fig. ] [illustration: fig. ] development of river systems the chalk and overlying tertiary strata were uplifted from the sea in great folds forming a series of such turtle-backs as we have been considering. the line of upheaval was not south-west and north-east, as that which raised the older formations in bands across england, but took place in an east and west direction. the main upheaval was that of the great wealden anticline. other folds produced the sandown and brook anticlines, and that of the portsdown hills. the upheaval seemed to have been caused by pressure acting from the south, for the steeper slope of each fold is on the northern side. our latest oligocene strata are tilted with the chalk, showing that the upheaval took place after oligocene times. but the great movement was in the main earlier than the pliocene. for on the north downs near lenham is a patch of lower pliocene deposit resting directly on the chalk, the older tertiary strata having been removed by denudation, clearly due to the uplift of the wealden anticline. the raising of the pliocene deposit to its present position proves that the same movement was continued at a later time, probably during the pleistocene. but the greater part of the movement may be assigned to the miocene, the period of great world-movements which raised the alps and the himalaya. many remarkable, and, at first sight, very puzzling features connected with the courses of rivers find an explanation when we study the river history. thus, looking at the weald of kent and sussex, we see that it consists of comparatively low ground rising to a line of heights east and west along the centre, and surrounded on all sides but the south-east by a wall of chalk downs. if we considered the subject, we should suppose that the drainage of the country would be towards the south-east, which is open to the sea. not so. all the rivers flow from the central heights north and south,--go straight for the walls of chalk downs, and cut through the escarpment in deep clefts to flow into the thames and the channel. this is explained when we remember that the rivers began to flow when the great curve of strata rose above the sea. though eroded by the sea during its elevation, yet when it rose above the waters the arch of chalk must have been continuous from what are now north downs to south. and from the centre line of the great turtle back the streams began to flow north and south, cutting in the course of ages deep channels for themselves. the greater erosion in their higher courses has cut away the mass of chalk from the centre of the weald, but the rivers still flow in the direction determined when the arch was still entire. we have a similar state of things in the isle of wight. any one not knowing the geological story, and looking at the geography of the island, might naturally suppose that there would be a stream flowing from west to east, through the low ground between the two ranges of downs, and finding its way into the sea in sandown bay. instead of this the three rivers of the island, the two yars and the medina, all flow north, and cut through the chalk escarpment of the central downs, as if an earthquake had made rifts for them to pass, and so find their way into the solent. the explanation is the same as in the case of the weald. the rivers began to flow when the chalk strata were continuous over the centre of the island; and their course was determined when the east and west anticlinal axis rose above the sea. we shall notice, however, that the island rivers start from south of the anticlinal axis. the centre of the sandown anticline runs just north of sandown, but the various branches of the yar and medina flow from well south of this. the explanation would appear to be that the anticline is almost a monoclinal curve,--that is to say, one slope is steep, the other not far from horizontal. streams starting from the ridge would flow with much greater force down the northern than the southern side, and would cut back their course much more quickly. thus they would continually cut into the heads of the southern streams, and turn the water supplying them into their own channels. in its early history a river cuts out its bed, and carries along pebbles, sand and mud to the sea. the head waters are constantly cutting back, and the slope becoming less steep, till a time comes when the stream in its gently inclined lower course has no more power to excavate, and the finer sediment, which is all that now reaches the lower river, begins to fill up the old channel. and so the alluvium is formed which fills the lower portions of our river valleys. beyond this, the great rush of waters from melting snows and ice of the glacial period has come to an end. the gentler and diminished streams of a drier age have no power to roll flint stones along and form beds of gravel. gravel terraces border our river valleys at a higher level than the present streams. periods alternated during which gravels were laid down by the river, and when the river acquiring more erosive force, by an elevation of the land giving its bed a steeper gradient, or a wetter climate producing a greater rush of water, cut a new channel deeper in the old valley. so our valleys in southern england are frequently bordered by a succession of gravel terraces, the higher ones being the older, dating from times when the river flowed at a higher level than at present. such terraces may be seen above the eastern yar and its tributary streams. in the centre of the old gravels is the alluvial flat of a later age. the island rivers cut out their channels when the land stood at a higher level than at present. the old channels of the lower parts of the rivers are now filled with alluvium, partly brought down by the rivers and partly marine. the channels are cut down considerably below sea level; and by the sinking of the land the sea has flowed in, and the last parts of the river courses are now tidal estuaries. the sea does not cut out estuaries. they are the submerged ends of river valleys. some idea may be formed of the antiquity of our island rivers by observing the depth of the clefts they have cut through the downs at brading, newport, and freshwater. but to this we must add the depth at which the old channels lie below the alluvium. it would be interesting to know the thickness of the alluvium. but it is not often that borings come to be made in river alluvia. however, in the old spithead forts artesian wells are sunk; and these pass through to feet of recent deposits before entering eocene strata. under st. helen's fort, at the mouth of brading harbour, are feet of recent deposits. the old channel of the yar, at its mouth, must lie at least at this depth. before it passes through the gap in the chalk downs the yar has meandered about, and formed the alluvial flat called morton marshes. these marshes stretch out into the flat known as sandown level, which occupies the shore of the bay between sandown and the granite fort. what is the meaning of this extension of the alluvium away from the course of the river out to the sea at sandown? a glance at it as pictured on a geological map will suggest the answer. we see clearly the alluvia of two streams converging from right and left, and uniting to pass to the sea through brading harbour. but the stream to the right has been cut off by the sea encroaching on sandown bay: only the last mile of alluvium is left to tell of a river passed away. we must reconstruct the past. we see the bay covered by land sloping up to east and south east, the lines of downs extending eastward from dunnose and the culvers, and an old river flowing northward, and cutting through the chalk at brading after being joined by a branch from the west. this old river must have been the main stream. for it was a transverse stream, flowing nearly at right angles to the ridge of the anticline; while the yar comes in as a tributary in the direction of the strike. of other tributary streams, all from the right are gone by the destruction of the old land. on the left streams would flow in from the combes at shanklin and luccombe--streams which have now cut out shanklin and luccombe chines. passing the gap in the downs the river meandered about, and, with marine deposit, washed in by the tides, formed the expanse of alluvium which occupies what was brading harbour,--a harbour which in old times presented at high tide a beautiful spectacle of land-locked water extending up to brading. inclosures and drainings have been made from time to time, the upper part near yarbridge being taken in in the time of edward i. further innings were made in the reign of queen elizabeth; and sir hugh middleton, who brought the new river to london, made an attempt to enclose the whole, but the sea broke through his embankment. the harbour was finally reclaimed at great cost in , the present embankment enclosing an area of acres. the history of the western yar is similar to that of the eastern. the main stream must have flowed from land now destroyed by the sea stretching far south of freshwater gate. all that is left is its tidal estuary, and the gravel terraces and alluvial flat formed in the last part of its course. of a tributary stream an interesting relic remains. for more than miles from chilton chine through brook to compton grange a bed of river gravel lies at the top of the cliff, marking the course of an old stream, of which coast erosion has made a longitudinal section. this was a tributary of the yar, when the mammoth left his remains in the gravel at grange chine and freshwater gate. down the centre of the gravels lies a strip of alluvium laid down by a stream following the same course in later days. the sea had probably by this time cut into the stream; and it most likely flowed into the sea somewhere west of brook. in the alluvium hazel nuts and twigs of trees are found at shippard's chine near brook. the lower course of the medina is a submerged river valley, the tide flowing up to newport. the river rises near chale, and flows through a strip of alluvium, overgrown with marsh vegetation, known as "the wilderness." this upper course of the medina, from the absence of gravels or brick earth, has the appearance of a comparatively modern river. but the medina has a further history. if you look at the map you will see branches of the yar running south to north as transverse streams, but the main course is that of a lateral river. look at the two chief sources of the yar--the stream from near whitwell and niton, and that from the wroxall valley. when they get down to the marshes near rookley and merston, they are not flowing at all in the direction of sandown or brading. they rather look as if they would flow along the marshy flat by blackwater into the medina. but the yar cuts right across their course, and carries them off eastward to sandown. when we look, we find a line of river valley with a strip of alluvium running up from the medina at blackwater in the direction of these two streams--a valley which the railway up the yar valley from sandown makes use of to get to newport. there can be little doubt that these streams from niton and wroxall originally ran along this line into the medina; but the yar, cutting its course backward, has captured them, and diverted their course. they probably represent the main branches of the medina in earlier times, the direction of flow from south-east to north-west instead of south to north being possibly due to the overlapping in the neighbourhood of newport of the ends of the brook and sandown anticlines. the sheet of gravel on blake down belongs to this period of the river's history. the river must have diverted between the deposition of the plateau gravels and that of the valley gravels of the yar. for the former follow the original valley, the latter the new course of the river. we must now take a wider outlook, and see what became of our rivers after they had flowed across what is now the isle of wight from south to north. we have been speaking of times when the island was of much greater extent than at present. standing on the down above the needles, and looking westward, we see on a clear day the isle of purbeck lying opposite, and we can see that the headland there is formed by white chalk cliffs like those beneath us. in front of them stand the old harry rocks, answering to the needles, both relics of a former extension of the land. in fact purbeck is just like a continuation of the isle of wight. south of the chalk lie greensand and wealden strata in swanage bay, and north towards poole are tertiaries. clearly these strata were once continuous with those of the isle of wight. we must imagine the chalk downs of the island continued as a long range across what is now sea, and on through purbeck. a great valley must have stretched from west to east, north of this line, along the course of the frome, which runs through dorset, and now enters the sea at poole harbour, on by bournemouth, and along the present solent channel--a valley still much above sea level, not yet cut down by rivers and the sea--and down the centre of this valley a river must have flowed, which may be called the river solent. it received as tributaries from the south the rivers of the isle of wight, and others from land since destroyed by the sea. there flowed into it from the north the waters of the stour and avon, and an old river which flowed down the line of what is now southampton water. southampton water looks like the valley of a large river, much larger than the present test and itchen. its direction points to a river from the north west; and it has been shown by mr. clement reid that the salisbury rivers--avon, nadder, and wily--at a former time, when they flowed far above their present level--continued their course into the valley of southampton water. for fragments of purbeck rocks from the vale of wardour, west of salisbury, have been found by him in gravels on high land near bramshaw, carried right over the deep vale of the avon in the direction of the water. the lower avon would originally be a tributary of the solent river; and it enters the sea about mid-way between the needles and the chalk cliffs of purbeck, just opposite the point where we might suppose the sea would have first broken through the line of chalk downs. no doubt it broke through a gap made by the course of an old river from the south, as it is now breaking through the gap made by the old yar at freshwater. when the river solent had been tapped at this point, the avon just opposite would have acquired a much steeper flow, causing it to cut back at a faster rate, till it cut the course of the old river which ran by salisbury to southampton, and, having a steeper fall, diverted the upper waters of this river into its own channel. [illustration: fig. the old solent river] frost and rain and rivers cut down the valleys of the river system for hundreds of feet; the sea which had broken through the chalk range gradually cut away the south side of the main river valley from purbeck to the needles; and eventually the valley itself was submerged by a subsidence of the land, and the sea flowed between the isle of wight and the mainland. a gravel of somewhat different character to the rest is the sheet of flint shingle at bembridge foreland. it forms a cliff of gravel about feet high resting on bembridge marls, and consists of large flints, with lines of smaller flints and sand showing current bedding, and also contains greensand chert and sandstone, which must have been brought from some district beyond the chalk. the shingle slopes to north-east. to the south-west it ends abruptly, the dividing line between shingle and marls running up steeply into the cliff. this evidently marks an old sea cliff in the marls, against which the gravel has been laid down.[ ] one or two comparatively recent deposits may be mentioned here. at the top of the cliff in totland bay, about ft. above the sea, for a distance of yards, is a lacustrine deposit, consisting in the main of a calcareous tufa deposited by springs flowing from the limestone of headon hill. the tufa contains black lines from vegetable matter, and numerous land and freshwater shells of present-day species--many species of helix, especially h. nemoralis and h. rotundata, cyclostoma elegans, limnæa palustris, pupa, clausilia, cyclas, and others. on the top of gore cliff is a deposit of hard calcareous mud, reaching a thickness of about feet, and forming a small vertical cliff above the slopes of chalk marl. it extends north a few yards beyond the chalk marl on to lower greensand. it has been formed by rainwash from a hill of chalk, which must once have existed to the south. the deposit contains numerous existing land-shells, especially _helix nemoralis_ and other species of helix. between atherfield and chale at the top of the cliff is a large area of blown sand. the sand is blown up from the face of the cliff below. it reaches a thickness of feet, and possibly more in places, and forms a line of sand dunes along the edge of the cliff. the upper part of ladder chine shows an interesting example of wind-erosion. the sand driven round it by the wind has worn it into a semi-circular hollow like a roman theatre. small spits, consisting partly of blown sand, extend opposite the mouths of the western yar, the newtown river, and the most extensive--at the mouth of the old brading harbour, separating the present reduced bembridge harbour from the sea. this is called st. helen's spit, or "dover,"--the local name for these sand spits. [footnote : fig. , p. .] chapter xii the coming of man. we have watched the long succession of varied life on the earth recorded in the rocks, and now we come to the most momentous event of all in the history--the coming of man. the first certain evidence of the presence of man on the earth is found with the coming of the glacial period,--unless indeed the supposed flint implements found by mr. reid moir, under the crag in suffolk, should prove him earlier still. it is a rare chance that the skeleton of a land animal is preserved; especially rare in the case of a skeleton so frail as that of man. the best chance for the preservation of bones is in deposits in caves, which were frequently the dens of wild beasts and the shelters of man. but the implements used by early man were happily of a very imperishable nature. his favourite material, if he could get it, was flint. flint could by dexterous blows have flake after flake taken off, till it formed a tool or weapon with sharp point and cutting edge. the implements, though only chipped, or flaked, were often admirably made. they have very characteristic shapes. moreover, the kind of blow--struck obliquely--by which these early men made their tools left marks which stamp them as of human workmanship. the flake struck off shows what is called a "bulb of percussion"--a swelling which marks the spot where the blow was struck--and from this extends a series of ripples, producing a surface like that of a shell, from which this mode of breaking is called conchoidal fracture. often, by further chipping the flake itself is worked into an implement. implements have also been made of chert, but it is far more difficult to work, as it naturally breaks in an irregular way into sharp angular fragments. flint, on the other hand, lent itself admirably to the use of early man, who in time acquired a perfect mastery of the material. the working of flints is so characteristic that, once accustomed to them, you cannot mistake a good specimen. sea waves dashing pebbles about will sometimes produce a conchoidal fracture, but never a series of fractures in the methodical way in which a flint was worked by man. and, of course, specimens may be found so worn that it is difficult to be sure about their nature. again early man may, especially in very early times, have been content to use a sharp stone almost as he found it, with only the slightest amount of knocking it into shape. so that in such a case it will be very difficult to decide whether the stones have formed the implements of man or not. in later times men learnt to polish their implements, and made polished stone axes like those the new zealanders and south sea islanders used to make in modern times. the old age of chipped or flaked implements is called the palæolithic; the later age when they were ground or polished the neolithic. (simple implements, as knives and scrapers, were still unpolished.) the history of early man is a long story in itself, and of intense interest. but we must not leave our geological story unfinished by leaving out the culmination of it all in man. in the higher gravels--the plateau gravels--no remains of man are found; but in the lower--the valley gravels,--of the south of england is found abundant evidence of the presence of man. large numbers of flint implements have been collected from the thames valley and over the whole area of the rivers which have gravel terraces along their course. over a large sheet of gravel at southampton, whenever a large gravel pit is dug, implements are found at the base of the gravel.[ ] the occurrence of the mammoth and other arctic creatures in the gravels shows that in the glacial period man was contemporary with these animals. remains in caves tell the same story. in limestone caverns in devon, derbyshire, and yorkshire, implements made by man are found in company with remains of the cave bear, cave hyæna, lion, hippopotamus, rhinoceros, and other animals either extinct or no longer inhabitants of this country--remains which have been preserved under floors of stalagmite deposited in the caves. in caves of central france men have left carvings on bone and ivory, representing the wild animals of that day--carvings which show a remarkable artistic sense, and a keen observation of animal life. among them is a drawing of the mammoth on a piece of mammoth ivory, showing admirably the appearance of the animal, with his long hair, as he has been found preserved in ice to the present day near the mouths of siberian rivers. drawings of the reindeer, true to life, are frequent. till recently very few palæolithic implements had been recorded as found in the isle of wight. in the memoir of the geological survey ( ) only one such is recorded, found in a patch of brick earth near howgate farm, bembridge.[ ] a few more implements, which almost certainly came from this brick-earth, have been found on the shore since. in recent years a large number of palæolithic implements have been found at priory bay near st. helen's. they were first observed on the beach by prof. e. b. poulton, f.r.s., in , and were traced to their source in the gravel in the cliff by miss moseley in . from that time, and especially from onwards, many have been found by prof. poulton, by r. w. poulton (and others). up to about implements had been found, and there have been more finds since.[ ] the most important finds, besides those at priory bay, have been those of mr. s. hazzledine warren at freshwater, especially in trial borings in loam and clay below the surface soil in a depression of the high downs, south of headon hill, at a level of about ft. o.d., in which a number of palæolithic tools, flakes, and cores were found[ ]. isolated implements have been found in recent years in various localities in the island. there are references to finds of implements at different times in the past, but the descriptions are generally too vague to conclude certainly to what date they belong. much of the gravel used in the island comes from the angular gravel on st. boniface down, or the high plateau gravel of st. george's down; but in the lower gravels and associated brick earth, it is highly probable that more remains of palæolithic man will yet be found in the island, and quite possible that such have been found in the past, but for want of accurate descriptions of the circumstances of the finds are lost to us. we must pass on to the men of the neolithic or later stone age. the palæolithic age was of very great duration, much longer than all succeeding human history. between palæolithic and neolithic times there is in england a large gap. in france various stages have been traced showing a continual advance in culture. in england little, if anything, has been found belonging to the intermediate stages. such remains may yet be found in caves, or in lower river gravels, now buried below the alluvium. the gap between palæolithic and neolithic is marked by the great amount of river erosion which took place in the interval. palæolithic implements are found in gravels formed when the rivers flowed some feet above their present courses. take, _e.g._, the itchen at southampton. after the foot gravels were deposited the river cut down, not merely to its present level, but to an old bed now covered up by various deposits beneath the river. after cutting down to that bed the river laid down gravels upon it; and then--the land standing at a higher level than to-day--the river valley and the surrounding country were covered by a forest, which, as the climate altered and became damper, was succeeded by the formation of peat. the land has since sunk, and the peat, in parts ft. thick, is now found under southampton water, covered by estuarine silt. the empress dock at southampton was dug where a mud bank was exposed at low water. the mud bank was formed of river silt to feet thick. below this was the peat, resting on gravel. on the gravel horns of reindeer were found. in the peat were large horn cores of the great extinct ox, _bos primigenius_, also horns of red deer, and also in the peat were found neolithic flint chips, a circular stone hammer head, with a hole bored through for a wooden handle, and a large needle made of horn. here, at a great interval of time after palæolithic man, as we see by the history of the river we have just traced, we come to the new race of men, the neolithic. when neolithic man appeared the land stood higher than at present, though not so high as during great part of the pleistocene. britain was divided from the continent, but the shores were a good way out into what is now sea round the coasts, and forests clothed these further shores. remains of these, known as submerged forest, are found below the tide mark round many parts of our coast. peat as at southampton docks, is found under the estuarine mud off netley. the wells at the spithead forts show an old land surface with peat more than feet below the tide level. the old bed of the solent river lies much lower still-- feet below high tide at noman's land fort; this channel was probably an estuary after the subsidence of the land till it silted up with marine deposits to the level on which the submerged forest grew. when the solent and southampton water were wooded valleys with rivers flowing down the middle, the isle of wight rivers were tributaries to the solent river, and the forest, as might be expected, extended up their valleys, and covered the low ground of the island. under the alluvial flats are remains of buried forests. in digging a well at sandford in large trunks of hard oak were found blocking the sinking of the well. when the land sank the sea flowed up the river valleys, converting them into strait and estuary, and largely filling up the channels with the silt, which now covers the peat. in the silt of newtown river are found bones of _bos primigenius_, which was found with the neolithic remains in the peat of southampton docks. the remains of neolithic man are not only found in submerged forests, but over the present surface of the land, or buried in recent deposits. he has left us the tombs of his chiefs, known as long barrows--great mounds of earth covering a row of chambers made of flat stones, such as the mounds of new grange in ireland, and the cromlechs or dolmens still standing in wales and cornwall. these consist of a large flat or curved stone--it may be feet in length,--supported on three or four others. originally a great mound of earth or stones was piled on top. these have generally been removed since by the hand of later man. the stones have been taken for road metal, the earth to lay on the land. the great cromlech at lanyon in cornwall was uncovered by a farmer, who had removed cart loads of earth to lay on his stony land before he had any idea that it was not a natural mound. then he came on the great cromlech underneath. another form of monument was the great standing stone or menhir, one of which, the longstone on the down above mottistone still stands to mark the tomb of some chieftain of, it may be, , years ago. the implements of neolithic man are found all over england, the smooth polished axe head, commonly called a celt (lat. _celtis_, a chisel), the chipped arrow head, the flaked flint worked by secondary chipping on the edge into a knife, or a scraper for skins; and much more common than the implement, even of the simplest description, are the waste flakes struck off in the making. very few stone celts have been found in the isle of wight. the flakes are extremely numerous, and a scraper or knife may often be found. they are turned up by the plough on the surface of the fields, in the earth of which they have been preserved from rubbing and weathering. they have however, acquired a remarkable polish, or "patina"--how is not clearly explained--which distinguishes their surface from the waxy appearance of newly-broken flint. in places the ground is so covered with flakes that we can have no doubt that these are the sites of settlements. the implements were made from the black flints fresh out of the chalk, and we can locate the neolithic flint workings. in our northern range of downs where the strata are vertical the layers of flint in the upper chalk run out on the top of the downs, only covered with a thin surface soil. in places where this soil has been removed--as in digging a quarry--the chalk is seen to be covered with flakes similar to those found on the lower ground, save that they are weathered white from lying exposed on the hard chalk, instead of on soft soil into which they would gradually sink by the burrowing of worms. it is probable that these flakes would be found more or less along the range of downs under the surface soil. in places on the undercliff have been found what are known as kitchen middens--heaps of shells which have accumulated near the huts of tribes of coast dwellers, who lived on shellfish. one such was formerly exposed in the stream below the old church at bonchurch, and is believed to extend below the foundations of the church. after a long duration of neolithic times a great step in civilisation took place with the introduction of bronze. bronze implements were introduced into this country probably some time about b.c. - ; and bronze continued to be the best material of manufacture till the introduction of iron some two or three centuries before the visit of julius caesar to these islands. to the early bronze age belong the graves of ancient chieftains known as round barrows, of which many are to be seen on the island downs. funeral urns and other remains have been found in these, some of which are now in the museum at carisbrooke castle. belonging to later times are the remains of the roman villa at brading and smaller remains of villas in other places; and cemeteries of anglo-saxon date, rich in weapons and ornaments, which have been excavated on chessil and bowcombe downs. but the study of the remains of ancient man forms a science in itself--archæology. in studying the periods of palæolithic and neolithic man we have stood on the borderland where geology and archæology meet. we have seen that vast geological changes have taken place since man appeared on earth. we must remember that the geological record is still in process of being written. it is not the record of a time sundered from the present day, but continuous with our own times; and it is by the study of processes still in operation that we are able to read the story of the past. [footnote : mr. w. dale, f.s.a.] [footnote : see figure , p. .] [footnote : see account by r. w. poulton in f. morey's "guide to the natural history of the isle of wight."] [footnote : surv. mem., i.w., , p. .] chapter xiii. the scenery of the island--conclusion. after studying the various geological formations that enter into the composition of the isle of wight, and learning how the island was made, it will be interesting to take a general view of the scenery, and see how its varied character is due to the nature of its geology. it would hardly be possible to find anywhere an area so small as this little island with such a variety of geological formations. the result is a remarkable variety in the scenery. the main feature of the island is the range of chalk downs running east and west, and terminating in the bold cliffs of white chalk at freshwater and the culvers. here we have vertical cliffs of great height, their white softened to grey by weathering and the soft haze through which they are often seen. in striking contrast of colour are the red cliff of lower greensand adjoining the culvers, and the many-coloured sands of alum bay joining on to the chalk of freshwater. the summits of the chalk downs have a characteristic softly rounded form, and the chalk is covered with close short herbage suited to the sheep which frequently dot the green surface. where sheets of flint gravel cap the downs, as on st. boniface, they are covered by furze and heather, producing a charming variation from the smooth turf where the surface is chalk. the lower greensand forms most of the undulating country between the two ranges of downs; while the upper greensand, though occupying a smaller area, produces one of the most conspicuous features of the scenery--the walls of escarpment that form the inland cliffs between shanklin and wroxall, gat cliff above appuldurcombe, the fine wall of gore cliff above rocken end, and the line of cliffs above the undercliff. to the gault clay is due the formation of the undercliff--the terrace of tumbled strata running for miles well above the sea, but sheltered by an upper cliff on the north, and in parts overgrown with picturesque woods. the impervious gault clay throws out springs around the downs, which form the headwaters of the various island streams. the upper division of the lower greensand, the sandrock, forms picturesque undulating foothills, often wooded, as at apsecastle, and at appuldurcombe and godshill park. on a spur of the sandrock stands godshill church, a landmark visible for miles around. at atherfield we have a fine line of cliffs of lower greensand, while the wealden strata on to brook form lower and softer cliffs. to the north of the central downs the tertiary sands and clays, often covered by plateau gravel, form an extended slope towards the solent shore, much of it well wooded, and presenting a charming landscape seen from the tops of the downs. this slope of tertiary strata is deeply cut into by streams, which form ravines and picturesque creeks, as wootton creek, feet below the level of the surrounding country. while much of the island coast is a line of vertical cliff, the northern shores are of gentler aspect, wooded slopes reaching to the water's edge, or meadow land sloping gradually to the sea level. opposite the mouths of streams are banks of shingle and sand dunes, forming the spits locally known as "dovers." some of these, in particular, st. helen's spit, afford interesting hunting grounds for the botanist. the great variety of soil and situation renders the isle of wight a place of interest to the botanist. we have the plants of chalk downs, of the sea cliff and shore, of the woods and meadows, of lane and hedgerow, and of the marshes. the old villages of the island, often occupying very picturesque situations--as godshill on a spur of the southern downs, newchurch on a bluff overlooking the yar valley, shorwell nestling among trees in a south-looking hollow of the downs, brighstone with its old church cottages and farmhouses among trees and meadows between down and sea--the old and interesting churches, the thatched cottages, the old manor houses of elizabethan or jacobean date, now mostly farm houses, for which the island is famous, add to the varied natural beauty. one of the most characteristic features of the southern coasts of the island, should be mentioned, the chines,--narrow ravines which cut inland from the coast through the sandstone and clays of the greensand and wealden strata, and along the beds of which small streams flow to the sea. narrow and steep-sided,--the name by which they are called is akin to _chink_--they are in striking contrast to the more open valleys of the streams which flow into the solent on the north shore of the island. the most beautiful is shanklin chine. the cliff at the mouth of the chine, just inside which stands a picturesque fisherman's cottage with thatched roof, is ft. high; and the chasm runs inland for yds., to where a very reduced cascade (for the water thrown out of the upper greensand by the gault clay is tapped at its source for the town supply) falls vertically over a ledge produced by hard ferruginous beds of the greensand. above the cascade the ravine runs on, but much shallower, for some yards. the lower ravine has much beauty, tall trees rising up the sides, and overshadowing the chasm, the banks thickly clothed with large ferns and other verdure. much wilder are the chines on the south-west of the island. the cascade at blackgang falls over hard ferruginous beds (to which the beds over which shanklin cascade falls--though on a smaller scale--probably correspond). the chine above these beds, being hollowed out in the soft clays and sands of the sandrock series, is much more open. whale chine is a long winding ravine between steep walls, the stream at the bottom making its way through blocks of fallen strata. the cause of these chines seems to be the same in all cases. it may be noticed that shanklin and luccombe chines are cut in the floors of open combes,--wide valleys with gently sloping floors; and at each side of these chines is to be seen the gravel spread over the floor of the old valley. it can scarcely be doubted that these combes are the heads of the valleys of the old streams, which flowed down a gradual slope till they joined the old branch (or, rather the old main river)[ ] of the yar, flowing over land extending far over what is now sandown bay. when the sea encroached, and cut into the course of this old river, and on till it made a section of what had been the left slope of the valley, the old tributaries of the yar now fell over a line of cliff into the sea. they thus gained new erosive power, and cut back at a much greater rate new and deeper channels; with the result that narrow trenches were cut in the floors of the old gently sloping valleys. the chines on the s.w. coast are to be explained in a similar way. they have been cut back with vertical sides, because the encroachment of the sea caused the streams to flow over cliffs, and so gave then power to cut back ravines at so fast a rate that the weathering down of the sides could not keep pace with it. the remarkable wind-erosion of these bare south-westerly cliffs by a sort of sand-blast driven before the gales to which that stretch of coast is exposed has already been referred to. a few words in conclusion to the reader. i have tried to show you something of the interest and wonder of the story written in the rocks. we have seen something of the world's making, and of the many and varied forms of life which have succeeded each other on its surface. we have had a glimpse of great and deep problems suggested, which are gradually receiving an answer. geology has the advantage that it can be studied by all who take walks in the country, and especially by those who visit any part of the sea coast, without the need of elaborate and costly scientific instruments and apparatus. any country walk will suggest problems for solution. i have tried to lead you to observe nature accurately, to think for yourselves, to draw your own conclusions. i have shown you how to try to solve the questions of geology by looking around you at what is taking place to-day, and by applying this knowledge to explain the records which have reached us of what has happened in the past. you are not asked to accept the facts of the geological story on the word of the writer, or on the authority of others, but to think for yourselves, to learn to weigh evidence, to seek only to find out the truth, whether it be geology you are studying or any other subject, and to follow the truth whithersoever it leads. [footnote : see p. .] table of strata recent. peat and river alluvium. pleistocene. plateau gravels: valley gravels and brick-earth. { pliocene} absent from the isle of wight. { miocene } { { { marine, corbula beds { { hamstead { freshwater & estuarine. { { { { { bembridge marls { { bembridge { { { beds { bembridge limestone { { { oligocene { osborne and st. helen's beds. { { tertiary { { { upper. freshwater and brackish { { headon { middle. marine { { beds { lower. freshwater and brackish { { { barton} barton sand. { { beds} barton clay. { { { eocene { bracklesham beds. { { bagshot sands { { london clay { { plastic clay (reading beds) { { white { upper chalk (chalk with flints) { { chalk { middle chalk (chalk { { { without flints) { { { { { a. plenus marls { upper { lower { grey chalk { cretaceous { chalk { chalk marl { { { chloritic marl { { { { { upper { chert beds { { selbornian { greensand { sandstone and { { { rag beds mesozoic { { gault or { secondary{ { carstone { { lower { sandrock and clays { { greensand { ferruginious sands { { { atherfield clay { lower { { perna bed { cretaceous { { { { shales { { wealden { variegated marls for further study. memoirs of the geological survey. general memoir of the isle of wight, date . new edition, entitled "a short account of the geology of the isle of wight," by h. j. osborne white, f.g.s., , price s. the memoirs are the great authority for the geology of the island: technical; books for geologists. the new edition is more condensed than the original, but contains much later research. mantell's "geological excursions round the isle of wight," . by one of the great early geologists. long out of print, but worth getting, if it can be picked up second-hand. norman's "guide to the geology of the isle of wight," , still to be obtained of booksellers in the island. gives details of strata, and lists of fossils, with pencil drawings of fossils. other books bearing on the subject have been mentioned in the text and foot-notes. an excellent geological map of the island, printed in colour, scale in. to the mile, full of geological information, is published by the survey at s. a good collection of fossils and specimens of rocks from the various strata of the isle of wight has recently been arranged at the sandown free library, and should be visited by all interested in the geology of the island. it should prove a most valuable aid to all who take up the study, and a great assistance in identifying any specimens they may themselves find. [illustration] geological map of the isle of wight index words in italics refer to a page where the meaning of a term is given. agates, , , alum bay, - ammonites, , , , _anticline_, astronomical theory of ice age, , atherfeld, avon river, barrows, , barton, belemnites, bembridge limestone, -- shingle at, benettites, "blue slipper," bonchurch, , bos primigenius, , botany, bracklesham, , brading harbour, , bronze age, brook, building stone, , carstone, , chalcedony, , , chale, chalk, divisions of, , , -- marl, -- rock, chalybeate springs, chert, chloritic marl, climate. coal, , colwell bay, compton bay, , conglomerate, modern, "crackers," cretaceous. crioceras, current bedding, cycads. denudation, , , , , _dip_, echinoderms, , eocene, erosion, marine, " pre-tertiary, _escarpment_, _faults_, fault at brook, flint, origin of, " implements, flora, alum bay, " eocene, , " wealden, , foraminifera, , gat cliff, gault, glacial period, - glauconite, , , gore cliff, , greensand, lower, - " upper, gravels, , , , - hamstead, , headon hill, - hempstead, see hamstead. hyopotamus, ice age, - iguanodon, insect limestone, iron ore, , iron pyrites, landslips, , limnæa, , , lobsters, atherfield, london clay, luccombe, landslip at, mammalian remains, , mammoth, , marvel, medina, melbourn rock, miocene, , , nautilus, , needles, neolithic man, newtown river, nummulites, oligocene, palæolithic man, perna bed, , pine raft, planorbis, , , plastic clay, priory bay, purbeck marble, quarr, rag, rock (place), roman villas, st. boniface down, , , st. george's down, , sandown anticline, - , sandrock, , scaphites, scenery, sea urchins, , , shanklin chine, solent, southampton dock, " water, sponges in flint, stone age, strata, table of, , _strike_, submerged forest, swanage, _syncline_, table of strata, , tertiary, totland bay, , tufa, turtle, , , undercliff, formation of, , volcanic action, wealden, whitcliff bay, - wood, fossil, , , , , yar, eastern, - " western, zones of chalk, , _printed by the crypt house press, bell lane, gloucester._ transcriber's notes with the exception of the changes noted below, the text in this file is the same as that in the original printed version. these may include alternate spelling from what may be common today (for example, gneisse); punctuational and/or grammatical nuances. additionally, several missing periods were inserted; but are not listed below. lastly, the index seems to be missing a few references to page numbers and were left as originally printed. emphasis encoding _text_ - italicized text $text$ - greek translation typographical corrections page : regious => regions page : sourrounding => surrounding page : remains in the peat => ... in ... page : surounding => surrounding none [illustration: from a painting by james hall, esq. engraved by s. williams. strata of red sandstone, slightly inclined, resting on vertical schist, at the siccar point, berwickshire. to illustrate unconformable stratification. see page . _"the mind seemed to grow giddy by looking so far into the abyss of time; and while we listened with earnestness and admiration to the philosopher who was now unfolding to us the order and series of these wonderful events, we became sensible how much farther reason may sometimes go than imagination can venture to follow."_--playfair, biography of hutton.] a manual of elementary geology: or, the ancient changes of the earth and its inhabitants as illustrated by geological monuments. by sir charles lyell, m.a. f.r.s. author of "principles of geology," "travels in north america," "a second visit to the united states," etc. etc. "it is a philosophy which never rests--its law is progress: a point which yesterday was invisible is its goal to-day, and will be its starting post to-morrow." edinburgh review, no. . p. . july, . _fourth and entirely revised edition._ illustrated with woodcuts. london: john murray, albemarle street. . london: spottiswoodes and shaw, new-street-square. preface to the fourth edition. in consequence of the rapid sale of the third edition of the "manual," of which copies were printed in january last, a new edition has been called for in less than a twelvemonth. even in this short interval some new facts of unusual importance in palæontology have come to light, or have been verified for the first time. instead of introducing these new discoveries into the body of the work, which would render them inaccessible to the purchasers of the former edition, i have given them in a postscript to this preface (printed and sold separately), and have pointed out at the same time their bearing on certain questions of the highest theoretical interest.[v-a] as on former occasions, i shall take this opportunity of stating that the "manual" is not an epitome of the "principles of geology," nor intended as introductory to that work. so much confusion has arisen on this subject, that it is desirable to explain fully the different ground occupied by the two publications. the first five editions of the "principles" comprised a th book, in which some account was given of systematic geology, and in which the principal rocks composing the earth's crust and their organic remains were described. in subsequent editions this book was omitted, it having been expanded, in , into a separate treatise called the "elements of geology," first re-edited in , and again recast and enlarged in , and entitled "a manual of elementary geology." although the subjects of both treatises relate to geology, as their titles imply, their scope is very different; the "principles" containing a view of the _modern_ changes of the earth and its inhabitants, while the "manual" relates to the monuments of _ancient_ changes. in separating the one from the other, i have endeavoured to render each complete in itself, and independent; but if asked by a student which he should read first, i would recommend him to begin with the "principles," as he may then proceed from the known to the unknown, and be provided beforehand with a key for interpreting the ancient phenomena, whether of the organic or inorganic world, by reference to changes now in progress. owing to the former incorporation of the two subjects in one work, and the supposed identity of their subject matter, it may be useful to give here a brief abstract of the contents of the "principles," for the sake of comparison. _abstract of the "principles of geology," eighth edition._ book i. . historical sketch of the early progress of geology, chaps. i. to iv. . circumstances which combined to make the first cultivators of the science regard the former course of nature as different from the present, and the former changes of the earth's surface as the effects of agents different in kind and degree from those now acting, chap. v. . whether the former variations in climate established by geology are explicable by reference to existing causes, chaps. vi. to viii. . theory of the progressive development of organic life in former ages, and the introduction of man into the earth, chap. ix. . supposed former intensity of aqueous and igneous causes considered, chaps. x. and xi. . how far the older rocks differ in texture from those now forming, chap. xii. . supposed alternate periods of repose and disorder, chap. xiii. book ii. changes now in progress in the inorganic world. . aqueous causes now in action: floods--rivers--carrying power of ice--springs and their deposits--deltas--waste of cliffs and strata produced by marine currents: chaps. xiv. to xxii. . permanent effects of igneous causes now in operation: active volcanos and earthquakes--their effects and causes: chaps. xxiii. to xxxiii. book iii. changes of the organic world now in progress. . doctrine of the transmutation of species controverted, chaps. xxxiv. and xxxv. . whether species have a real existence in nature, chaps. xxxvi. and xxxvii. . laws which regulate the geographical distribution of species, chaps. xxxviii. to xl. . creation and extinction of species, chaps. xli. to xliv. . imbedding of organic bodies, including the remains of man and his works, in strata now forming, chaps. xlv. to l. . formation of coral reefs, chap. li. it will be seen on comparing this analysis of the contents of the "principles" with the headings of the chapters of the present work (see p. xxiii.), that the two treatises have but little in common; or, to repeat what i have said in the preface to the th edition of the "principles," they have the same kind of connection which chemistry bears to natural philosophy, each being subsidiary to the other, and yet admitting of being considered as different departments of science.[vi-a] charles lyell. _ harley street, london, december . ._ footnotes: [v-a] postscript to th edition of the manual, price _d._ [vi-a] as it is impossible to enable the reader to recognize rocks and minerals at sight by aid of verbal descriptions or figures, he will do well to obtain a well-arranged collection of specimens, such as may be procured from mr. tennant ( . strand), teacher of mineralogy at king's college, london. postscript. tracks of a lower silurian reptile in canada--chelonian footprints in old red sandstone, morayshire--skeleton of a reptile in the same formation in scotland--eggs of batrachians (?) in a lower division of the "old red," or devonian--footprints of lower carboniferous reptiles in the united states--fossil rain-marks of the carboniferous period in nova scotia--triassic mammifer from the keuper of stuttgart--cretaceous gasteropoda--dicotyledonous leaves in lower cretaceous strata--bearing of the recent discoveries above-mentioned on the theory of the progressive development of animal life. _tracks of a lower silurian reptile in canada._--in the year , mr. robert abraham announced in the montreal gazette, of which he was editor, that the track of a freshwater tortoise had been observed on the surface of a stratum of sandstone in a quarry opened on the banks of the st. lawrence at beauharnais in upper canada. the inhabitants of the parish being perfectly familiar with the track of the amphibious mud-turtles or terrapins of their country, assured mr. abraham that the fossil impressions closely resembled those left by the recent species on sand or mud. having satisfied himself of the truth of their report, he was struck with the novelty and geological interest of the phenomenon. imagining the rock to be the lowest member of the old red sandstone, he was aware that no traces had as yet been found of a reptile in strata of such high antiquity. he was soon informed by mr. logan, at that time engaged in the geological survey of canada, that the white sandstone above montreal was really much older than the "old red," or devonian. it had in fact been ascertained many years before, by the state surveyors of new york (who called it the "potsdam sandstone"), to lie at the base of the whole silurian series. as such it had been pointed out to me in , in the valley of the mohawk, by mr. james hall[vii-a], and its position was correctly described by mr. emmons, on the borders of lake champlain, where i examined it in . it has there the character of a shallow-water deposit, ripple-marked throughout a considerable thickness, and full of a species of lingula. the flat valves of this shell, of a dark colour, are so numerous, and so arranged in horizontal layers, as to play the part of mica, causing the rock to divide into laminæ, as in some micaceous sandstones. when i mentioned this rock in my travels[vii-b] as occurring between kingston and montreal, (the same in which the chelonian foot-prints have since been found,) i spoke of it as the lowest member of the lower silurian series; but no traces of any organic being of a higher grade than the lingula had then been seen in it, and i called attention to the singular fact, that the oldest fossil form then known in the world, was a marine shell strictly referable to a genus now existing. early in the year , mr. logan laid before the geological society of london a slab of this sandstone from beauharnais, containing no less than twenty-eight foot-prints of the fore and hind feet of a quadruped, and six casts in plaster of paris, exhibiting a continuation of the same trail. each cast contained from twenty-six to twenty-eight impressions with a median channel equidistant from the two parallel rows of foot-prints, the one made by the feet of the right side, the other by those of the left. in these specimens a greater number of successive foot-marks belonging to one and the same series were displayed than had ever before been observed in any rock ancient or modern. mr. abraham has inferred that the breadth of the quadruped was from five to seven inches. a detailed account of the trail was published by professor owen, in april , from which the following extracts are made. "the foot-prints are in pairs, and the pairs extend in two parallel series, with a channel exactly midway between the right and left series. the pairs of the same side succeed each other at intervals, varying from one inch and a half to two inches and a half, the common distance being about two inches. the interval between the right and left pairs, measured from the inner border of the small prints, is three inches and a half, and from the outer border of the exterior or large prints, is seven inches. the shallow median track is one inch and a quarter in breadth, varying in depth, but not in its relative position to the right and left foot prints." "the inference to be deduced from these characters is, that the impressions were made by a quadruped with the hind feet larger and somewhat wider apart than the fore feet, with both hind and fore feet either very short, or prevented by some other part of the animal's structure from making long steps; and with the limbs of the right side wide apart from those of the left; consequently, that the quadruped had a broad trunk in proportion to its length, supported on limbs either short, or capable only of short steps, and with rounded and stumpy feet, not provided with long claws. there are faint traces of a fine reticulate pattern of the cuticle of the sole at the bottom of some of the foot-prints on one portion of the sandstone; and the surface of the sand is generally smoother there than where not impressed, which, with the rising of the sand at the border of the prints, indicates the weight of the impressing body. the median groove may be interpreted as due either to the abdomen or the tail of the animal; but as there is no indication of any bending or movement of a tail from side to side, it was probably scooped out of the soft sand by a hard breast-plate or plastron. if this were so, it may be inferred that the species was a freshwater or estuary tortoise rather than a land tortoise."[viii-a] previously to this discovery, the trias was the oldest stratum in which any remains or signs of a chelonian had been detected. numerous other trails have since been observed ( - ) in various localities in canada, all in the same very ancient fossiliferous rock; and mr. logan, who has visited the spots, will shortly publish a description of the phenomena. _chelonian foot-prints in old red sandstone, morayshire._--captain lambart brickenden has just communicated to the geological society of london a drawing and description of a continuous series of no less than thirty-four foot-prints of a quadruped observed in the course of last year ( ), on a slab of sandstone quarried at cummingstone, near elgin, in morayshire, a rock which has always been considered as an upper member of the devonian or "old red."[ix-a] a part of the track, the course of which was from a to b, is represented in the annexed woodcut, fig. . the foot-prints are in pairs, forming two parallel rows, which are somewhat less distant from each other than those of the lower silurian tortoise of canada above mentioned. the stride, on the other hand, is four inches, or twice that of the beauharnais chelonian. the hind foot is exactly of the same size, being one inch in diameter, and larger than the fore foot in the proportion of four to three. [illustration: fig. . scale one-sixth the original size. part of the trail of a (chelonian?) quadruped from the old red sandstone of cummingstone, near elgin, morayshire.--captain brickenden.] _skeleton of a reptile, allied to the batrachians, in the old red sandstone of morayshire._--mr. patrick duff, author of a "sketch of the geology of morayshire" (elgin, ), obtained recently (october, ), from the rock above alluded to, the first example ever seen of the skeleton of a reptile in the old red sandstone. he has kindly allowed me to give a figure of this fossil, of which dr. mantell has drawn up a detailed osteological account for publication in the "journal of the geological society of london." the bones in this specimen have decomposed, but the natural position of almost all of them can be seen, and nearly perfect casts of their form taken from the hollow moulds which they have left. the matrix is a fine-grained, whitish sandstone, with a cement of carbonate of lime. the skeleton exhibits the general characters of the lacertians, blended with peculiarities that are batrachian. hence dr. mantell infers that this reptile was either a freshwater batrachian, resembling the triton, or a small terrestrial lizard. slight indications are visible of very minute conical teeth. captain brickenden, who is well acquainted with the geology of that part of scotland, informs me that this fossil was found in the hill of spynie, north of the town of elgin, in a rock quarried for building, and the same in which the chelonian foot-prints, alluded to in the last page, occur. the skeleton is about four and a half inches in length, but part of the tail is concealed in the rock. dr. mantell has proposed for it the generic name of telerpeton, from +têle+, afar off, and +herpeton+, a reptile; while the specific name elginense commemorates the principal place near which it was obtained. [illustration: fig. . natural size. _telerpeton elginense._ (mantell.) reptile of old red sandstone, from near elgin, morayshire.] _eggs of batrachians (?) in the old red sandstone of scotland._--at page . of this work i have given two figures (figs. and .) of small groups of eggs, very common in the shales and sandstones of the "old red" of kincardineshire, forfarshire, and fife. i threw out as a conjecture, that they might belong to gasteropodous mollusca, like those represented in fig. . p. .; but dr. mantell, some years ago, showed me a small bundle of the dried-up eggs of the common english frog (see fig. _a_.), black and carbonaceous, and so identical in appearance with the fossils in question, that he suggested the probability of these last being of batrachian origin. the plants by which they are often accompanied (fig. . p. .), i formerly supposed to be fuci, but mr. bunbury tells me that their grass-like form agrees well with the idea of their being freshwater, and of the family fluviales. the absence of all shells, so far as our researches have yet gone, in the slates and sandstones of scotland above alluded to, raises a presumption against their marine origin, and a still stronger one against the fossil eggs being those of gasteropoda. it is well known that a single female of the batrachian tribe ejects annually an astonishing quantity of spawn. mr. newport, author of many accurate researches into the metamorphoses of the amphibia, having examined my fossils from forfarshire, concurs in dr. mantell's opinion that the clusters of eggs (figs. . . p. .) may be those of frogs; while other larger ones, occurring singly or in pairs in the same slates, and often attached to a leaf, may be the ova of a gigantic triton or salamander. (see figs. , , .) i may observe that the subdivision of the old red sandstone, in which these plants and ova occur (no. . of the section, fig. . p. .), is considerably lower in position than the rock in which the telerpeton of elgin is imbedded. [illustration: fig. . fossil.--old red. fig. . slab of old red sandstone, forfarshire, with eggs of batrachians. _a._ ova in a carbonized state. _b._ egg cells; the ova shed.] [illustration: fig. . recent. fig. . eggs of the common frog, _rana temporaria_, in a carbonized state, from a dried-up pond in clapham common. _a._ the ova. _b._ a transverse section of the mass exhibiting the form of the egg-cells.] [illustration: fig. . eggs of batrachians.--old red sandstone. fig. . shale of old red sandstone, or devonian, forfarshire, with impression of plants and eggs of batrachians. _a._ two pair of ova resembling those large salamanders or tritons on the same leaf. _b b._ detached ova. _c._ egg-cells of frogs or _ranina_.] _foot-prints of lower carboniferous reptiles in the united states._--i have stated, at p. ., that in , mr. isaac lea observed the foot-marks of a large reptile in the lowest beds of the coal formation at pottsville, about seventy miles n.e. of philadelphia. these researches have since been carried farther by professor h. d. rogers, in the same region of anthracitic coal, lying on the eastern flank of the alleghany mountains. beneath the productive coal-measures of that country occurs a dense mass of red shales and sandstones, which correspond nearly in position to the millstone grit and mountain limestone of the south-east of england. in these beds foot-prints, referred to three species of quadrupeds, have lately been detected, all of them five-toed and in double rows, with an opposite symmetry, as if made by right and left feet, while they likewise display the alternation of fore foot and hind foot. one species, the largest of the three, presents a diameter for each foot-print of about two inches, and shows the fore and hind feet to be nearly equal in dimensions. it exhibits a length of stride of about nine inches, and a breadth between the right and left treads of nearly four inches. the impressions of the hind feet are but little in the rear of the fore feet. the animal which made them is supposed to have been allied to a saurian, rather than to a batrachian or chelonian; but more information is required before so difficult a point can be decided. with these foot-marks were seen shrinkage cracks, such as are caused by the sun's heat in mud, and rain-spots, with the signs of the trickling of water on a wet, sandy beach; all confirming the conclusion derived from the foot-prints, that the quadrupeds belonged to air-breathers, and not to aquatic races.[xii-a] the cheirotherian foot-prints, figured by me at p. ., in which the fore and hind feet are very unequal in size, betoken a distinct genus, and occur in the midst of the productive coal measures, being consequently less ancient. _on fossil rain-marks of the carboniferous period in north america._--having alluded to the spots left by rain on the surface of carboniferous strata in the alleghanies, on which quadrupedal foot-prints are seen, i may mention that similar rain-prints are conspicuous in the coal measures of cape breton, in nova scotia, in which mr. richard brown has described stigmariæ and erect trunks of trees, and where there are proofs, as stated at p. ., of many fossil forests ranged one above the other. in such a region, if anywhere, might we expect to detect evidence of the fall of rain on a sea-beach, so repeatedly must the conditions of the same area have oscillated between land and sea. the intercalation of deposits, containing shells of marine or brackish water, indicate the constant proximity of a body of salt water when the clays which supported the upright trees were formed. in the course of , mr. brown had the kindness to send me some greenish slates from sydney, cape breton, on which are imprinted very delicate impressions of rain-drops, with several worm-tracks (_a_, _b_, fig. .), such as usually accompany rain-marks on the recent mud of the bay of fundy, and other modern beaches.[xii-b] [illustration: fig. . carboniferous rain-prints with worm-tracks (_a_, _b_) on green shale, from cape breton, nova scotia.] [illustration: fig. . casts of rain-prints on a portion of the same slab, no. . seen on the under side of an incumbent layer of arenaceous shale. the arrow represents the direction of the shower.] [illustration: fig. . casts of carboniferous rain-prints and shrinkage-cracks, (_a_) on the under side of a layer of sandstone, cape breton, nova scotia.] the casts of rain-prints, in figs. . and ., project from the under side of two layers, occurring at different levels, the one a sandy shale, resting on the green shale (fig. .), the other a sandstone presenting a similar warty or blistered surface, on which are also observable some small ridges as at _a_, which stand out in relief, and afford evidence of cracks formed by the shrinkage of subjacent clay, on which rain had fallen. many of the associated sandstones are described by mr. brown as ripple-marked. the great humidity of the climate of the coal period had been previously inferred from the nature of its vegetation and the continuity of its forests for hundreds of miles; but it is satisfactory to have at length obtained such positive proofs of showers of rain, the drops of which resembled in their average size those which now fall from the clouds. from such data we may presume that the atmosphere of the carboniferous period corresponded in density with that now investing the globe, and that different currents of air varied then as now, in temperature, so as to give rise, by their mixture, to the condensation of aqueous vapour. _triassic mammifer (microlestes antiquus plieninger.)_--in the year , professor plieninger, of stuttgart, published a description of two fossil molar teeth, referred by him to a warm-blooded quadruped[xiii-a], which he obtained from a bone-breccia in würtemberg occurring between the lias and the keuper. as the announcement of so novel a fact has never met with the attention it deserved, we are indebted to dr. jäger, of stuttgart, for having recently reminded us of it in his memoir on the fossil mammalia of würtemberg.[xiii-b] fig. . represents the tooth first found, taken from the plate published in , by professor plieninger; and fig. . is a drawing of the same executed from the original by mr. hermann von meyer, which he has been kind enough to send me. fig. . is a second and larger molar, copied from dr. jäger's plate lxxi., fig. . [illustration: fig. . _microlestes antiquus_, plieninger. molar tooth magnified. upper trias, diegerloch, near stuttgart, würtemberg. _a._ view of inner side? _b._ same, outer side? _c._ same in profile. _d._ crown of same.] [illustration: fig. . _microlestes antiquus_, plien. view of same molar as no. . from a drawing by herman von meyer. _a._ view of inner side? _b._ crown of same.] [illustration: fig. . molar of _microlestes_? plien. times as large as fig. . from the trias of diegerloch, stuttgart.] professor plieninger inferred in , from the double fangs of this tooth and their unequal size, and from the form and number of the protuberances or cusps on the flat crowns, that it was the molar of a mammifer; and considering it as predaceous, probably insectivorous, he called it microlestes, from +mikros+, little, and +lêstês+, a beast of prey. soon afterwards, he found the second tooth also, at the same locality, diegerloch, about two miles to the south-east of stuttgart. some of its cusps are broken, but there seem to have been six of them originally. from its agreement in general characters, it is supposed by professor plieninger to be referable to the same animal, but as it is four times as big, it may perhaps have belonged to another allied species. this molar is attached to the matrix consisting of sandstone, whereas the tooth, no. ., is isolated. several fragments of bone, differing in structure from that of the associated saurians and fish, and believed to be mammiferous, were imbedded near them in the same rock. mr. waterhouse, of the british museum, after studying the annexed figs. . . and the descriptions of prof. plieninger, observes, that not only the double roots of the teeth and their crowns presenting several cusps, resemble those of mammalia, but the cingulum also, or ridge surrounding the base of that part of the body of the tooth which was exposed or above the gum, is a character distinguishing them from fish and reptiles. "the arrangement of the six cusps or tubercles in two rows, in fig. ., with a groove or depression between them and the oblong form of the tooth, lead him, he says, to regard it as a molar of the lower jaw. both the teeth differ from those of the stonesfield mammalia[xiv-a], but do not supply sufficient data for determining to what order they belonged. even in regard to the stonesfield jaws, where we possess so much ampler materials, we cannot safely pronounce on the order." professor plieninger has sent me a cast of the smaller tooth, which exhibits well the characteristic mammalian test, the double fang; but mr. owen, to whom i have shown it, is not able to recognize its affinity with any mammalian type, recent or extinct, known to him. it has already been stated that the stratum in which the above-mentioned fossils occur is intermediate between the lias and the uppermost member of the trias. that it is really triassic may be deduced from the following considerations. in würtemberg there are two "bone-beds," one of great extent, and very rich in the remains of fish and reptiles, which intervenes between the muschelkalk and keuper, the other, containing the microlestes, less extensive and fossiliferous, which rests on the keuper, or superior member of the trias, and is covered by the sandstone of the lias. the last-mentioned breccia therefore occupies the same place as the well-known english "bone-bed" of axmouth and aust-cliff near bristol, which is shown[xv-a] to include characteristic species of muschelkalk fish, of the genus saurichthys, hybodus, and gyrolepis. in both the würtemberg bone-beds these three genera are also found, and one of the _species_, saurichthys mougeotii, is common to both the lower and upper breccias, as is also a remarkable reptile called nothosaurus mirabilis. the saurian called belodon by h. von meyer of the thecodont family, is another triassic form, associated at diegerloch with microlestes. previous to this discovery of professor plieninger, the most ancient of known fossil mammalia were those of the stonesfield slate, a subdivision of the lower oolite[xv-b] no representative of this class having as yet been met with in the fuller's earth, or inferior oolite (see table, p. .), nor in any member of the lias. _thecodont saurians._--this family of reptiles is common to the trias and permian groups in germany, and the geologists employed in the government survey of great britain have come to the conclusion, that the rock containing the two species alluded to at p. ., and of which the teeth are represented in figs. , ., ought rather to be referred to the trias than to the permian group. cretaceous gasteropoda. in speaking of the chalk of faxoe in denmark (p. .) or the highest member of the cretaceous series, i have remarked that it is characterized by univalve mollusca, both spiral and patelliform, which are wanting or rare in the white chalk of europe. this last statement requires, i find, some modification. it holds true in regard to certain forms, such as cypræa and oliva, found at faxoe; but m. a. d'orbigny enumerates species of gasteropoda from the white chalk (terrain sénonien) of france alone. the same author describes french species of gasteropoda from the chloritic chalk marl and upper greensand (turonien), from the gault, and from the lower greensand (neocomien), in all species of gasteropoda, from the cretaceous group below the maestricht beds. among these he refers to the genus mitra, to fusus, to trochus, to emarginula, and to cerithium. notwithstanding, therefore, the peculiarity of the chambered univalves of various genera, so abundant in the chalk, the mollusca of the period approximate in character to the tertiary and recent fauna far more than was formerly supposed. dicotyledonous leaves in lower cretaceous strata. m. adolphe brongniart when founding his classification of the fossiliferous strata in reference to their imbedded fossil plants, has placed the cretaceous group in the same division with the tertiary, that is to say, in his "age of angiosperms."[xvi-a] this arrangement is based on the fact, that the cretaceous plants display a transition character from the vegetation of the secondary to that of the tertiary periods. coniferæ and cycadeæ still flourished as in the preceding oolitic and triassic epochs; but with these fossils, some well-marked leaves of dicotyledonous trees referred to several species of the genus credneria, had been found in germany in the quadersandstein and pläner-kalk. still more recently, dr. debey of aix-la-chapelle has met with a great variety of other leaves of dicotyledonous plants in the cretaceous flora[xvi-b], of which he enumerates no less than species, some of the leaves being from four to six inches in length, and in a beautiful state of preservation. in the absence of the organs of fructification and of fossil fruits, the number of species may be exaggerated; but we may nevertheless affirm, reasoning from our present data, that in the lower chalk of aix-la-chapelle, dicotyledonous angiosperms flourished nearly in equal proportions with gymnosperms; a fact of great significance, as some geologists had wished to connect the rarity of dicotyledonous trees with a peculiarity in the state of the atmosphere in the earlier ages of the planet, imagining that a denser air and noxious gases, especially carbonic acid in excess, were adverse to the prevalence, not only of the quick-breathing classes of animals, (mammalia and birds,) but to a flora like that now existing, while it favoured the predominance of reptile life, and a cryptogamic and gymnospermous flora. the co-existence, therefore, of dicotyledonous angiosperms in abundance with cycads and coniferæ, and with a rich reptilian fauna comprising the iguanodon, ichthyosaurus, pliosaurus, and pterodactyl, in the lower cretaceous series tends, like the oolitic mammalia of stonesfield and stuttgart, and the triassic birds of connecticut, to dispel the idea of a meteorological state of things in the secondary periods widely distinct from that now prevailing. _general remarks._--in the preliminary chapters of "the principles of geology," in the first and subsequent editions, i have considered the question, how far the changes of the earth's crust in past times confirm or invalidate the popular hypothesis of a gradual improvement in the habitable condition of the planet, accompanied by a contemporaneous development and progression in organic life. it had long been a favourite theory, that in the earlier ages to which we can carry back our geological researches, the earth was shaken by more frequent and terrible earthquakes than now, and that there was no certainty nor stability in the order of the natural world. a few sea-weeds and zoophytes, or plants and animals of the simplest organization, were alone capable of existing in a state of things so unfixed and unstable. but in proportion as the conditions of existence improved, and great convulsions and catastrophes became rarer and more partial, flowering plants were added to the cryptogamic class, and by the introduction of more and more perfect species, a varied and complex flora was at last established. in like manner, in the animal kingdom, the zoophyte, the brachiopod, the cephalopod, the fish, the reptile, the bird, and the warm-blooded quadruped made their entrance into the earth, one after the other, until finally, after the close of the tertiary period, came the quadrumanous mammalia, most nearly resembling man in outward form and internal structure, and followed soon afterwards, if not accompanied at first, by the human race itself. the objections which, in , i urged against this doctrine[xvii-a], in so far as relates to the passage of the earth from a chaotic to a more settled condition, have since been embraced by a large and steadily increasing school of geologists; and in reference to the animate world, it will be seen, on comparing the present state of our knowledge with that which we possessed twenty years ago, how fully i was justified in declaring the insufficiency of the data on which such bold generalizations, respecting progressive development, were based. speaking of the absence, from the tertiary formations, of fossil quadrumana, i observed, in , that "we had no right to expect to have detected any remains of tribes which live in trees, until we knew more of those quadrupeds which frequent marshes, rivers, and the borders of lakes, such being usually first met with in a fossil state."[xvii-b] i also added, "if we are led to infer, from the presence of crocodiles and turtles in the london clay, and from the cocoa-nuts and spices found in the isle of sheppey, that at the period when our older tertiary strata were formed, the climate was hot enough for the quadrumana, we nevertheless could not hope to discover any of their skeletons, until we had made considerable progress in ascertaining what were the contemporary pachydermata; and not one of these has been discovered as yet in any strata of this epoch in england." nine years afterwards, when these fossil pachyderms had been found in the london clay, and in the sandy strata at its base, the remains of a monkey, of the genus macacus, were detected near woodbridge, in suffolk; and other quadrumana had been met with, a short time previously, in different stages of the tertiary series, in india, france, and brazil. when we consider the small area of the earth's surface hitherto examined geologically, and our scanty acquaintance with the fossil vertebrata, even of the environs of great european capitals, it is truly surprising that any naturalist should be rash enough to assume that the lower eocene deposits mark the era of the first creation of quadrumana. it is, however, still more unphilosophical to infer from a single extinct species of this order, obtained in a latitude far from the tropics, that the eocene quadrumana had not attained as high a grade of organization as those of our own times, when the naturalist is acquainted with all, or nearly all, the species of monkeys, apes and orangs which are contemporary with man. to return to the year , mammalia had not then been traced to rocks of higher antiquity than the stonesfield oolite, whereas we have just seen that memorials of this class have at length made their appearance in the trias of germany. in birds had been discovered no lower in the series than the paris gypsum, or middle eocene. their bones have now been found both in england and the swiss alps in the lower eocene, and their existence has been established by foot-prints in the triassic epoch in north america (p. .). reptiles in had not been detected in rocks older than the magnesian limestone, or permian formation; whereas the skeletons of four species have since been brought to light (see p. .) in the coal-measures, and one in the old red sandstone, of europe, while the footprints of three or four more have been observed in carboniferous rocks of north america, not to mention the chelonian trail above described, from the most ancient of the fossiliferous rocks of canada, the "potsdam sandstone," which lies at the base of the lower silurian system. (see above, p. vii.) lastly, the remains of fish, which in were scarcely recognized in deposits older than the coal, have now been found plentifully in the devonian, and sparingly in the silurian, strata; though not in any formation of such high antiquity as the chelonian of montreal. previously to the discovery last mentioned, it was by no means uncommon for paleontologists to speak with confidence of fish as having been created before reptiles. it was deemed reasonable to suppose that the introduction of a particular class or order of beings into the planet coincided, in date, with the age of the oldest rock to which the remains of that class or order happened then to have been traced back. to be consistent with themselves, the same naturalists ought now to take for granted that reptiles were called into existence before fish. this they will not do, because such a conclusion would militate against their favourite hypothesis of an ascending scale, according to which nature "evolved the organic world," rendering it more and more perfect in the lapse of ages. in our efforts to arrive at sound theoretical views on such a question, it would seem most natural to turn to the marine invertebrate animals as to a class affording the most complete series of monuments that have come down to us, and where we can find corresponding terms of comparison, in strata of every age. if, in this more complete series of her archives, nature had really exhibited a more simple grade of organization in fossils of the remotest antiquity, we might have suspected that there was some foundation of facts in the theory of successive development. but what do we find? in the lower silurian there is a full representation of the radiata, mollusca, and articulata proper to the sea. the marine fauna, indeed, in those three classes, is so rich as almost to imply a more perfect development than that which now peoples the ocean. thus, in the great division of the radiata, we find asteroid and helianthoid zoophytes, besides crinoid and cystidean echinoderms. in the mollusca of the same most ancient epoch m. barrande enumerates, in bohemia alone, the astonishing number of species of cephalopoda. in the articulata we have the crustaceans, represented by more than species of trilobites, not to mention other genera. it is only then, in reference to the vertebrata, that the argument of degeneracy in proportion as we trace fossils back to older formations can be maintained; and the dogma rests mainly for its support on negative evidence, whether deduced from the entire absence of the fossil representatives of certain classes in particular rocks, or the low grade of the first few species of a class which chance has thrown in our way. the scarcity of all memorials of birds in strata below the eocene, has been a subject of surprise to some geologists. the bones formerly referred to birds in the wealden and chalk, are now admitted to have belonged to flying reptiles, of various sizes, one of them from the kentish chalk so large as to have measured feet inches from tip to tip of its outstretched wings. whether some elongated bones of the stonesfield oolite should be referred to birds, which they seem greatly to resemble in microscopic structure or to pterodactyles, is a point now under investigation. if it should be proved that no osseous remains of the class aves have hitherto been derived from any secondary or primary formation, we must not too hastily conclude that birds were even scarce in these periods. the rarity of such fossils in the eocene marine strata is very striking. in , professor owen, in his "history of the fossil mammalia and birds of great britain," was unable to obtain more than four or five fragments of bones and skulls of birds from the london clay, by the aid of which four species were recognized. even so recently, therefore, as , as much was known of the mammalia of the stonesfield oolite, as of the ornithic fauna of our english eocene deposits. to reason correctly on the value of negative facts in this branch of paleontology, we must first have ascertained how far the relics of birds are now becoming preserved in new strata, whether marine, fluviatile, or lacustrine. i have explained, in the "principles of geology," that the imbedding of the bones of living birds in deposits now in progress in inland lakes appears to be extremely rare. in the shell-marl of scotland, which is made up bodily of the shells of the genera limneus, planorbis, succinea, and valvata, and in which the skeletons of deer and oxen abound, we find no bones of birds. yet we know that, before the lakes were drained which yield this marl used in agriculture, the surface of the water and the bordering swamps were covered with wild ducks, herons, and other fowl. they left no memorials behind them, because, if they perished on the land, their bodies decomposed or became the prey of carnivorous animals; if on the water, they were buoyant and floated till they were devoured by predaceous fish or birds. the same causes of obliteration have no power to efface the foot-prints which the same creatures may leave, under favourable circumstances, imprinted on an ancient mud-bank or shore, on which new strata may be from time to time thrown down. in the red mud of recent origin spread over wide areas by the high tides of the bay of fundy, innumerable foot-tracks of recent birds (tringa minuta) are preserved in successive layers, and hardened by the sun. yet none of the bones of these birds, though diligently searched for, have yet been discovered in digging trenches through the red mud. it is true that, in a few spots, the bones of birds have been met with plentifully in the older tertiary strata, but always in rocks of freshwater origin, such as the paris gypsum or the lacustrine limestone of the limagne d'auvergne. in strata of the same age, in belgium and other european countries, or in the united states, where no less careful search has been made, few, if any, fossil birds have come to light. we ought, therefore, most clearly to perceive that it is no part of the plan of nature to hand down to after times a complete or systematic record of the former history of the animate world. the preservation of the relics, even of aquatic tribes of animals, is an exception to the general rule, although time may so multiply exceptional cases that they may seem to constitute the rule; and may thus impose upon the imagination, leading us to infer the non-existence of creatures of which no monuments are extant. hitherto our acquaintance with the birds, and even the mammalia, of the eocene period has depended, almost everywhere, on single specimens, or on a few individuals found in one spot. it has therefore depended on what we commonly call chance; and we must not wonder if the casual discovery of a tertiary, secondary, or primary rock, rich in fossil impressions of the foot-prints of birds or quadrupeds, should modify or suddenly overthrow all theories based on negative facts. the chief reason why we meet more readily with the remains of every class in tertiary than in secondary strata, is simply that the older rocks are more and more exclusively marine in proportion as we depart farther and farther from periods during which the existing continents were built up. the secondary and primary formations are, for the most part, marine,--not because the ocean was more universal in past times, but because the epochs which preceded the eocene were so distant from our own, that entire continents have been since submerged. i have alluded at p. . to mr. darwin's account of the south american ostriches, seen on the coast of buenos ayres, walking at low water over extensive mud-banks, which are then dry, for the sake of feeding on small fish. perhaps no bird of such perfect organization as the eagle or vulture may ever accompany these ostriches. certainly, we cannot expect the condor of the andes to leave its trail on such a shore; and no traveller, after searching for footprints along the whole eastern coast of south america, would venture to speculate, from the results of such an inquiry, on the extent, variety, or development of the feathered fauna of the interior of that continent. the absence of cetacea from rocks older than the eocene has been frequently adduced as lending countenance to the theory of the late appearance of the highest class of vertebrata on the earth. that we have hitherto failed to detect them in the oolite or trias, does not imply, as we have now seen, that mammalia were not then created. even in the eocene strata of europe, the discovery of cetaceans has never kept pace with that of land quadrupeds. the only instance cited in great britain is a species of monodon, from the london clay, of doubtful authenticity as to its geological position. on the other hand, the gigantic zeuglodon of north america (see p. .), occurs abundantly in the middle eocene strata of georgia and alabama, from which as yet no bones of land-quadrupeds have been obtained. professor sedgwick states in a recent work[xxi-a], that he possesses in the woodwardian museum, a mass of anchylosed cervical vertebræ of a whale which he found near ely, and which he believes to have been washed out of the kimmeridge clay, a member of the upper oolite; but its true geological site is not well determined. it differs, says professor owen, from any other known fossil or recent whale. in the present imperfect state then of our information, we can scarcely say more than that the cetacea may have been scarce, in the secondary and primary periods. it is quite conceivable that when aquatic saurians, some of them carnivorous, like the ichthyosaurus, were swarming in the sea, and when there were large herbivorous reptiles, like the iguanodon, on the land, such reptiles may, to a certain extent, have superseded the cetacea, and discharged their functions in the animal economy. the views which i proposed originally in the principles of geology in opposition to the theory of progressive development may be thus briefly explained. from the earliest period at which plants and animals can be proved to have existed, there has been a continual change going on in the position of land and sea, accompanied by great fluctuations of climate. to these ever-varying geographical and climatal conditions the state of the animate world has been unceasingly adapted. no satisfactory proof has yet been discovered of the gradual passage of the earth from a chaotic to a more habitable state, nor of a law of progressive development governing the extinction and renovation of species, and causing the fauna and flora to pass from an embryonic to a more perfect condition, from a simple to a more complex organization. the principle of adaptation above alluded to, appears to have been analogous to that which now peoples the arctic, temperate, and tropical regions contemporaneously with distinct assemblages of species and genera, or which independently of mere temperature gives rise to a predominance of the marsupial tribe of quadrupeds in australia, and of the placental tribe in asia and europe, or to a profusion of reptiles without mammalia in the galapagos archipelago, and of mammalia without reptiles in greenland.[xxii-a] this theory implies, almost necessarily, a very unequal representation at successive periods of the principal classes and orders of plants and animals, if not in the whole globe, at least throughout very wide areas. thus, for example, the proportional number of genera, species, and individuals in the vertebrate class may differ, in two different and distinct epochs, to an extent unparalleled by any two contemporaneous faunas, because in the course of millions of ages, the contrast of climate and geographical conditions may exceed the difference now observable in polar and equatorial latitudes. i shall conclude by observing, that if the doctrine of successive development had been paleontologically true, as the new discoveries above enumerated show that it is not; if the sponge, the cephalopod, the fish, the reptile, the bird, and the mammifer had followed each other in regular chronological order--the creation of each class being separated from the other by vast intervals of time; and if it were admitted that man was created last of all, still we should by no means be able to recognize, in his entrance upon the earth, the last term of one and the same series of progressive developments. for the superiority of man, as compared to the irrational mammalia, is one of kind, rather than of degree, consisting in a rational and moral nature, with an intellect capable of indefinite progression, and not in the perfection of his physical organization, or those instincts in which he resembles the brutes. he may be considered as a link in the same unbroken chain of being, if we regard him simply as a new species--a member of the animal kingdom--subject, like other species, to certain fixed and invariable laws, and adapted like them to the state of the animate and inanimate world prevailing at the time of his creation. physically considered, he may form part of an indefinite series of terrestrial changes past, present, and to come; but morally and intellectually he may belong to another system of things--of things immaterial--a system which is not permitted to interrupt or disturb the course of the material world, or the laws which govern its changes.[xxii-b] footnotes: [vii-a] travels in north america by the author, vol. ii. chap. . [vii-b] ibid. . [viii-a] quart. journ. geol. soc. , vol. vii. p. . [ix-a] the generally received determination of the age of this rock is probably correct; but as there are no overlying coal-measures and no well-known devonian fossils in the whitish stone of elgin, and as i have not personally explored the geology of that district, i cannot speak as confidently as in regard to the age of the montreal chelonian. [xii-a] h. d. rogers, proceedings of amer. assoc. of science, albany, . [xii-b] see memoir by the author, quart. journ. geol. soc., vol. vii. p. . [xiii-a] würtembergisch. naturwissen. jahreshefte, jahr. stuttgart, . [xiii-b] nov. act. acad. cæsar. leopold. nat. cur. , p. . for figures, see ibid. plate xxi. figs. , , , . [xiv-a] see manual, p. . [xv-a] manual, p. . [xv-b] ibid. p. . [xvi-a] for terminology, see note, p. . [xvi-b] quart. journ. vol. vii. memoirs, p. . [xvii-a] principles, st ed. chaps. v. and ix. [xvii-b] ibid. p. . [xxi-a] preface to th ed. of studies of university of cambridge. [xxii-a] principles, th ed. , vol. i. p. , and vol. i. chap. . subsequent ed. [xxii-b] in my anniversary address, for , to the geological society, the reader will find a full discussion of the facts and arguments which bear on the theory of progressive development.--quart. journ. geol. soc., vol. vii. contents. chapter i. on the different classes of rocks. geology defined--successive formation of the earth's crust--classification of rocks according to their origin and age--aqueous rocks--their stratification and imbedded fossils--volcanic rocks, with and without cones and craters--plutonic rocks, and their relation to the volcanic--metamorphic rocks and their probable origin--the term primitive, why erroneously applied to the crystalline formations--leading division of the work page chapter ii. aqueous rocks--their composition and forms of stratification. mineral composition of strata--arenaceous rocks--argillaceous--calcareous--gypsum--forms of stratification--original horizontality--thinning out--diagonal arrangement--ripple mark chapter iii. arrangement of fossils in strata--freshwater and marine. successive deposition indicated by fossils--limestones formed of corals and shells--proofs of gradual increase of strata derived from fossils--serpula attached to spatangus--wood bored by teredina--tripoli and semi-opal formed of infusoria--chalk derived principally from organic bodies--distinction of freshwater from marine formations--genera of freshwater and land shells--rules for recognizing marine testacea--gyrogonite and chara--freshwater fishes--alternation of marine and freshwater deposits--lym-fiord chapter iv. consolidation of strata and petrifaction of fossils. chemical and mechanical deposits--cementing together of particles--hardening by exposure to air--concretionary nodules--consolidating effects of pressure--mineralization of organic remains--impressions and casts how formed--fossil wood--göppert's experiments--precipitation of stony matter most rapid where putrefaction is going on--source of lime in solution--silex derived from decomposition of felspar--proofs of the lapidification of some fossils soon after burial, of others when much decayed chapter v. elevation of strata above the sea--horizontal and inclined stratification. why the position of marine strata, above the level of the sea, should be referred to the rising up of the land, not to the going down of the sea--upheaval of extensive masses of horizontal strata--inclined and vertical stratification--anticlinal and synclinal lines--bent strata in east of scotland--theory of folding by lateral movement--creeps--dip and strike--structure of the jura--various forms of outcrop--rocks broken by flexure--inverted position of disturbed strata--unconformable stratification--hutton and playfair on the same--fractures of strata--polished surfaces--faults--appearance of repeated alternations produced by them--origin of great faults page chapter vi. denudation. denudation defined--its amount equal to the entire mass of stratified deposits in the earth's crust--horizontal sandstone denuded in ross-shire--levelled surface of countries in which great faults occur--coalbrook dale--denuding power of the ocean during the emergence of land--origin of valleys--obliteration of sea-cliffs--inland sea-cliffs and terraces in the morea and sicily--limestone pillars at st. mihiel, in france--in canada--in the bermudas chapter vii. alluvium. alluvium described--due to complicated causes--of various ages, as shown in auvergne--how distinguished from rocks _in situ_--river-terraces--parallel roads of glen roy--various theories respecting their origin chapter viii. chronological classification of rocks. aqueous, plutonic, volcanic, and metamorphic rocks, considered chronologically--lehman's division into primitive and secondary--werner's addition of a transition class--neptunian theory--hutton on igneous origin of granite--how the name of primary was still retained for granite--the term "transition," why faulty--the adherence to the old chronological nomenclature retarded the progress of geology--new hypothesis invented to reconcile the igneous origin of granite to the notion of its high antiquity--explanation of the chronological nomenclature adopted in this work, so far as regards primary, secondary, and tertiary periods chapter ix. on the different ages of the aqueous rocks. on the three principal tests of relative age--superposition, mineral character, and fossils--change of mineral character and fossils in the same continuous formation--proofs that distinct species of animals and plants have lived at successive periods--distinct provinces of indigenous species--great extent of single provinces--similar laws prevailed at successive geological periods--relative importance of mineral and palæontological characters--test of age by included fragments--frequent absence of strata of intervening periods--principal groups of strata in western europe chapter x. classification of tertiary formations.--post-pliocene group. general principles of classification of tertiary strata--detached formations scattered over europe--strata of paris and london--more modern groups--peculiar difficulties in determining the chronology of tertiary formations--increasing proportion of living species of shells in strata of newer origin--terms eocene, miocene, and pliocene--post-pliocene strata--recent or human period--older post-pliocene formations of naples, uddevalla, and norway--ancient upraised delta of the mississippi--loess of the rhine page chapter xi. newer pliocene period.--boulder formation. drift of scandinavia, northern germany, and russia--its northern origin--not all of the same age--fundamental rocks polished, grooved, and scratched--action of glaciers and icebergs--fossil shells of glacial period--drift of eastern norfolk--associated freshwater deposit--bent and folded strata lying on undisturbed beds--shells on moel tryfane--ancient glaciers of north wales--irish drift chapter xii. boulder formation--_continued_. difficulty of interpreting the phenomena of drift before the glacial hypothesis was adopted--effects of intense cold in augmenting the quantity of alluvium--analogy of erratics and scored rocks in north america and europe--bayfield on shells in drift of canada--great subsidence and re-elevation of land from the sea, required to account for glacial appearances--why organic remains so rare in northern drift--mastodon giganteus in united states--many shells and some quadrupeds survived the glacial cold--alps an independent centre of dispersion of erratics--alpine blocks on the jura--recent transportation of erratics from the andes to chiloe--meteorite in asiatic drift chapter xiii. newer pliocene strata and cavern deposits. chronological classification of pleistocene formations, why difficult--freshwater deposits in valley of thames--in norfolk cliffs--in patagonia--comparative longevity of species in the mammalia and testacea--fluvio-marine crag of norwich--newer pliocene strata of sicily--limestone of great thickness and elevation--alternation of marine and volcanic formations--proofs of slow accumulation--great geographical changes in sicily since the living fauna and flora began to exist--osseous breccias and cavern deposits--sicily--kirkdale--origin of stalactite--australian cave-breccias--geographical relationship of the provinces of living vertebrata and those of the fossil species of the pliocene periods--extinct struthious birds of new zealand--teeth of fossil quadrupeds chapter xiv. older pliocene and miocene formations. strata of suffolk termed red and coralline crag--fossils, and proportion of recent species--depth of sea and climate--reference of suffolk crag to the older pliocene period--migration of many species of shells southwards during the glacial period--fossil whales--subapennine beds--asti, sienna, rome--miocene formations--faluns of touraine--depth of sea and littoral character of fauna--tropical climate implied by the testacea--proportion of recent species of shells--faluns more ancient than the suffolk crag--miocene strata of bordeaux and piedmont--molasse of switzerland--tertiary strata of lisbon--older pliocene and miocene formations in the united states--sewâlik hills in india chapter xv. upper eocene formations. eocene areas in england and france--tabular view of french eocene strata--upper eocene group of the paris basin--same beds in belgium and at berlin--mayence tertiary strata--freshwater upper eocene of central france--series of geographical changes since the land emerged in auvergne--mineral character an uncertain test of age--marls containing cypris--oolite of eocene period--indusial limestone and its origin--fossil mammalia of the upper eocene strata in auvergne--freshwater strata of the cantal, calcareous and siliceous--its resemblance to chalk--proofs of gradual deposition of strata chapter xvi. eocene formations--_continued_. subdivisions of the eocene group in the paris basin--gypseous series--extinct quadrupeds--impulse given to geology by cuvier's osteological discoveries--shelly sands called sables moyens--calcaire grossier--miliolites--calcaire siliceux--lower eocene in france--lits coquilliers--sands and plastic clay--english eocene strata--freshwater and fluvio-marine beds--barton beds--bagshot and bracklesham division--large ophidians and saurians--lower eocene and london clay proper--fossil plants and shells--strata of kyson in suffolk--fossil monkey and opossum--mottled clays and sand below london clay--nummulitic formation of alps and pyrenees--its wide geographical extent--eocene strata in the united states--section at claiborne, alabama--colossal cetacean--orbitoid limestone--burr stone chapter xvii. cretaceous group. divisions of the cretaceous series in north-western europe--upper cretaceous strata--maestricht beds--chalk of faxoe--white chalk--characteristic fossils--extinct cephalopoda--sponges and corals of the chalk--signs of open and deep sea--white area of white chalk--its origin from corals and shells--single pebbles in chalk--siliceous sandstone in germany contemporaneous with white chalk--upper greensand and gault--lower cretaceous strata--atherfield section, isle of wight--chalk of south of europe--hippurite limestone--cretaceous flora--chalk of united states chapter xviii. wealden group. the wealden divisible into weald clay, hastings sand, and purbeck beds--intercalated between two marine formations--weald clay and cypris-bearing strata--iguanodon--hastings sands--fossil fish--strata formed in shallow water--brackish water-beds--upper, middle, and lower purbeck--alternations of brackish water, freshwater, and land--dirt-bed, or ancient soil--distinct species of fossils in each subdivision of the wealden--lapse of time implied--plants and insects of wealden--geographical extent of wealden--its relation to the cretaceous and oolitic periods--movements in the earth's crust to which it owed its origin and submergence chapter xix. denudation of the chalk and wealden. physical geography of certain districts composed of cretaceous and wealden strata--lines of inland chalk-cliffs on the seine in normandy--outstanding pillars and needles of chalk--denudation of the chalk and wealden in surrey, kent, and sussex--chalk once continuous from the north to the south downs--anticlinal axis and parallel ridges--longitudinal and transverse valleys--chalk escarpments--rise and denudation of the strata gradual--ridges formed by harder, valleys by softer beds--why no alluvium, or wreck of the chalk, in the central district of the weald--at what periods the weald valley was denuded--land has most prevailed where denudation has been greatest--elephant bed, brighton chapter xx. oolite and lias. subdivisions of the oolitic or jurassic group--physical geography of the oolite in england and france--upper oolite--portland stone and fossils--lithographic stone of solenhofen--middle oolite, coral rag--zoophytes--nerinæan limestone--diceras limestone--oxford clay, ammonites and belemnites--lower oolite, crinoideans--great oolite and bradford clay--stonesfield slate--fossil mammalia, placental and marsupial--resemblance to an australian fauna--doctrine of progressive development--collyweston slates--yorkshire oolitic coal-field--brora coal--inferior oolite and fossils chapter xxi. oolite and lias--_continued_. mineral character of lias--name of gryphite limestone--fossil shells and fish--ichthyodorulites--reptiles of the lias--ichthyosaur and plesiosaur--marine reptile of the galapagos islands--sudden destruction and burial of fossil animals in lias--fluvio-marine beds in gloucestershire and insect limestone--origin of the oolite and lias, and of alternating calcareous and argillaceous formations--oolitic coal-field of virginia, in the united states chapter xxii. trias or new red sandstone group. distinction between new and old red sandstone--between upper and lower new red--the trias and its three divisions--most largely developed in germany--keuper and its fossils--muschelkalk--fossil plants of bunter--triassic group in england--bone-bed of axmouth and aust--red sandstone of warwickshire and cheshire--footsteps of _chirotherium_ in england and germany--osteology of the _labyrinthodon_--identification of this batrachian with the chirotherium--origin of red sandstone and rock-salt--hypothesis of saline volcanic exhalations--theory of the precipitation of salt from inland lakes or lagoons--saltness of the red sea--new red sandstone in the united states--fossil footprints of birds and reptiles in the valley of the connecticut--antiquity of the red sandstone containing them chapter xxiii. permian or magnesian limestone group. fossils of magnesian limestone and lower new red distinct from the triassic--term permian--english and german equivalents--marine shells and corals of english magnesian limestone--palæoniscus and other fish of the marl slate--thecodont saurians of dolomitic conglomerate of bristol--zechstein and rothliegendes of thuringia--permian flora--its generic affinity to the carboniferous--psaronites or tree-ferns chapter xxiv. the coal or carboniferous group. carboniferous strata in the south-west of england--superposition of coal-measures to mountain limestone--departure from this type in north of england and scotland--section in south wales--underclays with stigmaria--carboniferous flora--ferns, lepidodendra, calamites, asterophyllites, sigillariæ, stigmariæ,--coniferæ--endogens--absence of exogens--coal, how formed--erect fossil trees--parkfield colliery--st. etienne, coal-field--oblique trees or snags--fossil forests in nova scotia--brackish water and marine strata--origin of clay-iron-stone chapter xxv. carboniferous group--_continued_. coal-fields of the united states--section of the country between the atlantic and mississippi--position of land in the carboniferous period eastward of the alleghanies--mechanically formed rocks thinning out westward, and limestones thickening--uniting of many coal-seams into one thick one--horizontal coal at brownsville, pennsylvania--vast extent and continuity of single seams of coal--ancient river-channel in forest of dean coal-field--absence of earthy matter in coal--climate of carboniferous period--insects in coal--rarity of air-breathing animals--great number of fossil fish--first discovery of the skeletons of fossil reptiles--footprints of reptilians--mountain limestone--its corals and marine shells chapter xxvi. old red sandstone, or devonian group. old red sandstone of scotland, and borders of wales--fossils usually rare--"old red" in forfarshire--ichthyolites of caithness--distinct lithological type of old red in devon and cornwall--term "devonian"--organic remains of intermediate character between those of the carboniferous and silurian systems--corals and shells--devonian strata of westphalia, the eifel, russia, and the united states--coral reef at falls of the ohio--devonian flora chapter xxvii. silurian group. silurian strata formerly called transition--term grauwacké--subdivisions of upper and lower silurian--ludlow formation and fossils--wenlock formation, corals and shells--caradoc and llandeilo beds--graptolites--lingula--trilobites--cystideæ--vast thickness of silurian strata in north wales--unconformability of caradoc sandstone--silurian strata of the united states--amount of specific agreement of fossils with those of europe--great number of brachiopods--deep-sea origin of silurian strata--absence of fluviatile formations--mineral character of the most ancient fossiliferous rocks chapter xxviii. volcanic rocks. trap rocks--name, whence derived--their igneous origin at first doubted--their general appearance and character--volcanic cones and craters, how formed--mineral composition and texture of volcanic rocks--varieties of felspar--hornblende and augite--isomorphism--rocks, how to be studied--basalt, greenstone, trachyte, porphyry, scoria, amygdaloid, lava, tuff--alphabetical list, and explanation of names and synonyms, of volcanic rocks--table of the analyses of minerals most abundant in the volcanic and hypogene rocks chapter xxix. volcanic rocks--_continued_. trap dike--sometimes project--sometimes leave fissures vacant by decomposition--branches and veins of trap--dikes more crystalline in the centre--foreign fragments of rock imbedded--strata altered at or near the contact--obliteration of organic remains--conversion of chalk into marble--and of coal into coke--inequality in the modifying influence of dikes--trap interposed between strata--columnar and globular structure--relation of trappean rocks to the products of active volcanos--submarine lava and ejected matter correspond generally to ancient trap--structure and physical features of palma and some other extinct volcanos chapter xxx. on the different ages of the volcanic rocks. tests of relative age of volcanic rocks--test by superposition and intrusion--dike of quarrington hill, durham--test by alteration of rocks in contact--test by organic remains--test of age by mineral character--test by included fragments--volcanic rocks of the post-pliocene period--basalt of bay of trezza in sicily--post-pliocene volcanic rocks near naples--dikes of somma--igneous formations of the newer pliocene period--val di noto in sicily chapter xxxi. on the different ages of the volcanic rocks--_continued_. volcanic rocks of the older pliocene period--tuscany--rome--volcanic region of olot in catalonia--cones and lava-currents--ravines and ancient gravel-beds--jets of air called bufadors--age of the catalonian volcanos--miocene period--brown-coal of the eifel and contemporaneous trachytic breccias--age of the brown-coal--peculiar characters of the volcanos of the upper and lower eifel--lake craters--trass--hungarian volcanos chapter xxxii. on the different ages of the volcanic rocks--_continued_. volcanic rocks of the pliocene and miocene periods continued--auvergne--mont dor--breccias and alluviums of mont perrier, with bones of quadrupeds--river dammed up by lava-current--range of minor cones from auvergne to the vivarais--monts dome--puy de côme--puy de pariou--cones not denuded by general flood--velay--bones of quadrupeds buried in scoriæ--cantal--eocene volcanic rocks--tuffs near clermont--hill of gergovia--trap of cretaceous period--oolitic period--new red sandstone period--carboniferous period--old red sandstone period--"rock and spindle" near st. andrews--silurian period--cambrian volcanic rocks chapter xxxiii. plutonic rocks--granite. general aspect of granite--decomposing into spherical masses--rude columnar structure--analogy and difference of volcanic and plutonic formations--minerals in granite, and their arrangement--graphic and porphyritic granite--mutual penetration of crystals of quartz and felspar--occasional minerals--syenite--syenitic, talcose, and schorly granites--eurite--passage of granite into trap--examples near christiania and in aberdeenshire--analogy in composition of trachyte and granite--granite veins in glen tilt, cornwall, the valorsine, and other countries--different composition of veins from main body of granite--metalliferous veins in strata near their junction with granite--apparent isolation of nodules of granite--quartz veins--whether plutonic rocks are ever overlying--their exposure at the surface due to denudation chapter xxxiv. on the different ages of the plutonic rocks. difficulty in ascertaining the precise age of a plutonic rock--test of age by relative position--test by intrusion and alteration--test by mineral composition--test by included fragments--recent and pliocene plutonic rocks, why invisible--tertiary plutonic rocks in the andes--granite altering cretaceous rocks--granite altering lias in the alps and in skye--granite of dartmoor altering carboniferous strata--granite of the old red sandstone period--syenite altering silurian strata in norway--blending of the same with gneiss--most ancient plutonic rocks--granite protruded in a solid form--on the probable age of the granites of arran, in scotland chapter xxxv. metamorphic rocks. general character of metamorphic rocks--gneiss--hornblende-schist --mica-schist--clay-slate--quartzite--chlorite-schist--metamorphic limestone--alphabetical list and explanation of other rocks of this family--origin of the metamorphic strata--their stratification is real and distinct from cleavage--joints and slaty cleavage--supposed causes of these structures--how far connected with crystalline action chapter xxxvi. metamorphic rocks--_continued_. strata near some intrusive masses of granite converted into rocks identical with different members of the metamorphic series--arguments hence derived as to the nature of plutonic action--time may enable this action to pervade denser masses--from what kinds of sedimentary rock each variety of the metamorphic class may be derived--certain objections to the metamorphic theory considered--lamination of trachyte and obsidian due to motion--whether some kinds of gneiss have become schistose by a similar action chapter xxxvii. on the different ages of the metamorphic rocks. age of each set of metamorphic strata twofold--test of age by fossils and mineral character not available--test by superposition ambiguous--conversion of dense masses of fossiliferous strata into metamorphic rocks--limestone and shale of carrara--metamorphic strata of modern periods in the alps of switzerland and savoy--why the visible crystalline strata are none of them very modern--order of succession in metamorphic rocks--uniformity of mineral character--why the metamorphic strata are less calcareous than the fossiliferous chapter xxxviii. mineral veins. werner's doctrine that mineral veins were fissures filled from above--veins of segregation--ordinary metalliferous veins or lodes--their frequent coincidence with faults--proofs that they originated in fissures in solid rock--veins shifting other veins--polishing of their walls--shells and pebbles in lodes--evidence of the successive enlargement and re-opening of veins--fournet's observations in auvergne--dimensions of veins--why some alternately swell out and contract--filling of lodes by sublimation from below--chemical and electrical action--relative age of the precious metals--copper and lead veins in ireland older than cornish tin--lead vein in lias, glamorganshire--gold in russia--connection of hot springs and mineral veins--concluding remarks * * * * * _dates of the successive editions of the "principles" and "elements" (or manual) of geology, by the author._ principles, st vol. in octavo, published in - - - jan. . ----, d vol. do. - - - - - - - - - - - - - - - - jan. . ----, st vol. d edition in octavo - - - - - - - . ----, d vol. d edition do. - - - - - - - - - - jan. . ----, d vol. st edition do. - - - - - - - - - - may . ----, new edition (called the d) of the whole work in vols. mo. - - - - - - - - - - - - - - - - - - - may . ----, th edition, vols. mo. - - - - - - - - - june . ----, th edition, do. do. - - - - - - - - - - - - mar. . elements, st edition in one vol. - - - - - - - - july . principles, th edition, vols. mo. - - - - - - june . elements, d edition in vols. mo. - - - - - - july . principles, th edition in one vol. vo. - - - - - feb. . ----, th edition, now published in one vol. vo. - may . manual of elementary geology (or "elements," d edition), now published in one vol. vo. - - - - - - - - - - - - jan. . _works by sir charles lyell._ i. travels in north america,-- - . with geological observations on the united states, canada, and nova scotia. with large coloured geological map and plates. vols. post vo. _s._ ii. a second visit to the united states,-- - . _second edition._ vols. post vo. _s._ iii. principles of geology; or the modern changes of the earth and its inhabitants considered, as illustrative of geology. _eighth edition, thoroughly revised._ with maps, plates, and woodcuts. vo. _s._ iv. a manual of elementary geology; or the ancient changes of the earth and its inhabitants, as illustrated by geological monuments. fourth edition. _thoroughly revised._ with woodcuts and plates. vo. _s._ manual of elementary geology. chapter i. on the different classes of rocks. geology defined--successive formation of the earth's crust--classification of rocks according to their origin and age--aqueous rocks--their stratification and imbedded fossils--volcanic rocks, with and without cones and craters--plutonic rocks, and their relation to the volcanic--metamorphic rocks and their probable origin--the term primitive, why erroneously applied to the crystalline formations--leading division of the work. of what materials is the earth composed, and in what manner are these materials arranged? these are the first inquiries with which geology is occupied, a science which derives its name from the greek +gê+, _ge_, the earth, and +logos+, _logos_, a discourse. previously to experience we might have imagined that investigations of this kind would relate exclusively to the mineral kingdom, and to the various rocks, soils, and metals, which occur upon the surface of the earth, or at various depths beneath it. but, in pursuing such researches, we soon find ourselves led on to consider the successive changes which have taken place in the former state of the earth's surface and interior, and the causes which have given rise to these changes; and, what is still more singular and unexpected, we soon become engaged in researches into the history of the animate creation, or of the various tribes of animals and plants which have, at different periods of the past, inhabited the globe. all are aware that the solid parts of the earth consist of distinct substances, such as clay, chalk, sand, limestone, coal, slate, granite, and the like; but previously to observation it is commonly imagined that all these had remained from the first in the state in which we now see them,--that they were created in their present form, and in their present position. the geologist soon comes to a different conclusion, discovering proofs that the external parts of the earth were not all produced in the beginning of things, in the state in which we now behold them, nor in an instant of time. on the contrary, he can show that they have acquired their actual configuration and condition gradually, under a great variety of circumstances, and at successive periods, during each of which distinct races of living beings have flourished on the land and in the waters, the remains of these creatures still lying buried in the crust of the earth. by the "earth's crust," is meant that small portion of the exterior of our planet which is accessible to human observation, or on which we are enabled to reason by observations made at or near the surface. these reasonings may extend to a depth of several miles, perhaps ten miles; and even then it may be said, that such a thickness is no more than / part of the distance from the surface to the centre. the remark is just; but although the dimensions of such a crust are, in truth, insignificant when compared to the entire globe, yet they are vast, and of magnificent extent in relation to man, and to the organic beings which people our globe. referring to this standard of magnitude, the geologist may admire the ample limits of his domain, and admit, at the same time, that not only the exterior of the planet, but the entire earth, is but an atom in the midst of the countless worlds surveyed by the astronomer. the materials of this crust are not thrown together confusedly; but distinct mineral masses, called rocks, are found to occupy definite spaces, and to exhibit a certain order of arrangement. the term _rock_ is applied indifferently by geologists to all these substances, whether they be soft or stony, for clay and sand are included in the term, and some have even brought peat under this denomination. our older writers endeavoured to avoid offering such violence to our language, by speaking of the component materials of the earth as consisting of rocks and _soils_. but there is often so insensible a passage from a soft and incoherent state to that of stone, that geologists of all countries have found it indispensable to have one technical term to include both, and in this sense we find _roche_ applied in french, _rocca_ in italian, and _felsart_ in german. the beginner, however, must constantly bear in mind, that the term rock by no means implies that a mineral mass is in an indurated or stony condition. the most natural and convenient mode of classifying the various rocks which compose the earth's crust, is to refer, in the first place, to their origin, and in the second to their relative age. i shall therefore begin by endeavouring briefly to explain to the student how all rocks may be divided into four great classes by reference to their different origin, or, in other words, by reference to the different circumstances and causes by which they have been produced. the first two divisions, which will at once be understood as natural, are the aqueous and volcanic, or the products of watery and those of igneous action at or near the surface. _aqueous rocks._--the aqueous rocks, sometimes called the sedimentary, or fossiliferous, cover a larger part of the earth's surface than any others. these rocks are _stratified_, or divided into distinct layers, or strata. the term _stratum_ means simply a bed, or any thing spread out or _strewed_ over a given surface; and we infer that these strata have been generally spread out by the action of water, from what we daily see taking place near the mouths of rivers, or on the land during temporary inundations. for, whenever a running stream charged with mud or sand, has its velocity checked, as when it enters a lake or sea, or overflows a plain, the sediment, previously held in suspension by the motion of the water, sinks, by its own gravity, to the bottom. in this manner layers of mud and sand are thrown down one upon another. if we drain a lake which has been fed by a small stream, we frequently find at the bottom a series of deposits, disposed with considerable regularity, one above the other; the uppermost, perhaps, may be a stratum of peat, next below a more dense and solid variety of the same material; still lower a bed of shell-marl, alternating with peat or sand, and then other beds of marl, divided by layers of clay. now, if a second pit be sunk through the same continuous lacustrine _formation_, at some distance from the first, nearly the same series of beds is commonly met with, yet with slight variations; some, for example, of the layers of sand, clay, or marl, may be wanting, one or more of them having thinned out and given place to others, or sometimes one of the masses first examined is observed to increase in thickness to the exclusion of other beds. the term "_formation_," which i have used in the above explanation, expresses in geology any assemblage of rocks which have some character in common, whether of origin, age, or composition. thus we speak of stratified and unstratified, freshwater and marine, aqueous and volcanic, ancient and modern, metalliferous and non-metalliferous formations. in the estuaries of large rivers, such as the ganges and the mississippi, we may observe, at low water, phenomena analogous to those of the drained lakes above mentioned, but on a grander scale, and extending over areas several hundred miles in length and breadth. when the periodical inundations subside, the river hollows out a channel to the depth of many yards through horizontal beds of clay and sand, the ends of which are seen exposed in perpendicular cliffs. these beds vary in colour, and are occasionally characterized by containing drift-wood or shells. the shells may belong to species peculiar to the river, but are sometimes those of marine testacea, washed into the mouth of the estuary during storms. the annual floods of the nile in egypt are well known, and the fertile deposits of mud which they leave on the plains. this mud is _stratified_, the thin layer thrown down in one season differing slightly in colour from that of a previous year, and being separable from it, as has been observed in excavations at cairo, and other places.[ -a] when beds of sand, clay, and marl, containing shells and vegetable matter, are found arranged in a similar manner in the interior of the earth, we ascribe to them a similar origin; and the more we examine their characters in minute detail, the more exact do we find the resemblance. thus, for example, at various heights and depths in the earth, and often far from seas, lakes, and rivers, we meet with layers of rounded pebbles composed of different rocks mingled together. they are like the shingle of a sea-beach, or pebbles formed in the beds of torrents and rivers, which are carried down into the ocean wherever these descend from high grounds bordering a coast. there the gravel is spread out by the waves and currents over a considerable space; but during seasons of drought the torrents and rivers are nearly dry, and have only power to convey fine sand or mud into the sea. hence, alternate layers of gravel and fine sediment accumulate under water, and such alternations are found by geologists in the interior of every continent.[ -a] if a stratified arrangement, and the rounded forms of pebbles, are alone sufficient to lead us to the conclusion that certain rocks originated under water, this opinion is farther confirmed by the distinct and independent evidence of _fossils_, so abundantly included in the earth's crust. by a _fossil_ is meant any body, or the traces of the existence of any body, whether animal or vegetable, which has been buried in the earth by natural causes. now the remains of animals, especially of aquatic species, are found almost everywhere imbedded in stratified rocks, and sometimes, in the case of limestone, they are in such abundance as to constitute the entire mass of the rock itself. shells and corals are the most frequent, and with them are often associated the bones and teeth of fishes, fragments of wood, impressions of leaves, and other organic substances. fossil shells, of forms such as now abound in the sea, are met with far inland, both near the surface, and at great depths below it. they occur at all heights above the level of the ocean, having been observed at elevations of feet in the pyrenees, , in the alps, , in the andes, and above , feet in the himalayas.[ -b] these shells belong mostly to marine testacea, but in some places exclusively to forms characteristic of lakes and rivers. hence it is concluded that some ancient strata were deposited at the bottom of the sea, and others in lakes and estuaries. when geology was first cultivated, it was a general belief, that these marine shells and other fossils were the effects and proofs of the deluge of noah; but all who have carefully investigated the phenomena have long rejected this doctrine. a transient flood might be supposed to leave behind it, here and there upon the surface, scattered heaps of mud, sand, and shingle, with shells confusedly intermixed; but the strata containing fossils are not superficial deposits, and do not simply cover the earth, but constitute the entire mass of mountains. nor are the fossils mingled without reference to the original habits and natures of the creatures of which they are the memorials; those, for example, being found associated together which lived in deep or in shallow water, near the shore or far from it, in brackish or in salt water. it has, moreover, been a favourite notion of some modern writers, who were aware that fossil bodies could not all be referred to the deluge, that they, and the strata in which they are entombed, might have been deposited in the bed of the ocean during the period which intervened between the creation of man and the deluge. they have imagined that the antediluvian bed of the ocean, after having been the receptacle of many stratified deposits, became converted, at the time of the flood, into the lands which we inhabit, and that the ancient continents were at the same time submerged, and became the bed of the present sea. this hypothesis, although preferable to the diluvial theory before alluded to, since it admits that all fossiliferous strata were successively thrown down from water, is yet wholly inadequate to explain the repeated revolutions which the earth has undergone, and the signs which the existing continents exhibit, in most regions, of having emerged from the ocean at an era far more remote than four thousand years from the present time. ample proofs of these reiterated revolutions will be given in the sequel, and it will be seen that many distinct sets of sedimentary strata, each several hundreds or thousands of feet thick, are piled one upon the other in the earth's crust, each containing peculiar fossil animals and plants which are distinguishable with few exceptions from species now living. the mass of some of these strata consists almost entirely of corals, others are made up of shells, others of plants turned into coal, while some are without fossils. in one set of strata the species of fossils are marine; in another, lying immediately above or below, they as clearly prove that the deposit was formed in a brackish estuary or lake. when the student has more fully examined into these appearances, he will become convinced that the time required for the origin of the rocks composing the actual continents must have been far greater than that which is conceded by the theory above alluded to; and likewise that no one universal and sudden conversion of sea into land will account for geological appearances. we have now pointed out one great class of rocks, which, however they may vary in mineral composition, colour, grain, or other characters, external and internal, may nevertheless be grouped together as having a common origin. they have all been formed under water, in the same manner as modern accumulations of sand, mud, shingle, banks of shells, reefs of coral, and the like, and are all characterized by stratification or fossils, or by both. _volcanic rocks._--the division of rocks which we may next consider are the volcanic, or those which have been produced at or near the surface whether in ancient or modern times, not by water, but by the action of fire or subterranean heat. these rocks are for the most part unstratified, and are devoid of fossils. they are more partially distributed than aqueous formations, at least in respect to horizontal extension. among those parts of europe where they exhibit characters not to be mistaken, i may mention not only sicily and the country round naples, but auvergne, velay, and vivarais, now the departments of puy de dome, haute loire, and ardèche, towards the centre and south of france, in which are several hundred conical hills having the forms of modern volcanos, with craters more or less perfect on many of their summits. these cones are composed moreover of lava, sand, and ashes, similar to those of active volcanos. streams of lava may sometimes be traced from the cones into the adjoining valleys, where they have choked up the ancient channels of rivers with solid rock, in the same manner as some modern flows of lava in iceland have been known to do, the rivers either flowing beneath or cutting out a narrow passage on one side of the lava. although none of these french volcanos have been in activity within the period of history or tradition, their forms are often very perfect. some, however, have been compared to the mere skeletons of volcanos, the rains and torrents having washed their sides, and removed all the loose sand and scoriæ, leaving only the harder and more solid materials. by this erosion, and by earthquakes, their internal structure has occasionally been laid open to view, in fissures and ravines; and we then behold not only many successive beds and masses of porous lava, sand, and scoriæ, but also perpendicular walls, or _dikes_, as they are called, of volcanic rock, which have burst through the other materials. such dikes are also observed in the structure of vesuvius, etna, and other active volcanos. they have been formed by the pouring of melted matter, whether from above or below, into open fissures, and they commonly traverse deposits of _volcanic tuff_, a substance produced by the showering down from the air, or incumbent waters, of sand and cinders, first shot up from the interior of the earth by the explosions of volcanic gases. besides the parts of france above alluded to, there are other countries, as the north of spain, the south of sicily, the tuscan territory of italy, the lower rhenish provinces, and hungary, where spent volcanos may be seen, still preserving in many cases a conical form, and having craters and often lava-streams connected with them. there are also other rocks in england, scotland, ireland, and almost every country in europe, which we infer to be of igneous origin, although they do not form hills with cones and craters. thus, for example, we feel assured that the rock of staffa, and that of the giant's causeway, called basalt, is volcanic, because it agrees in its columnar structure and mineral composition with streams of lava which we know to have flowed from the craters of volcanos. we find also similar basaltic and other igneous rocks associated with beds of _tuff_ in various parts of the british isles, and forming _dikes_, such as have been spoken of; and some of the strata through which these dikes cut are occasionally altered at the point of contact, as if they had been exposed to the intense heat of melted matter. the absence of cones and craters, and long narrow streams of superficial lava, in england and many other countries, is principally to be attributed to the eruptions having been submarine, just as a considerable proportion of volcanos in our own times burst out beneath the sea. but this question must be enlarged upon more fully in the chapters on igneous rocks, in which it will also be shown, that as different sedimentary formations, containing each their characteristic fossils, have been deposited at successive periods, so also volcanic sand and scoriæ have been thrown out, and lavas have flowed over the land or bed of the sea, at many different epochs, or have been injected into fissures; so that the igneous as well as the aqueous rocks may be classed as a chronological series of monuments, throwing light on a succession of events in the history of the earth. _plutonic rocks_ (granite, &c.).--we have now pointed out the existence of two distinct orders of mineral masses, the aqueous and the volcanic: but if we examine a large portion of a continent, especially if it contain within it a lofty mountain range, we rarely fail to discover two other classes of rocks, very distinct from either of those above alluded to, and which we can neither assimilate to deposits such as are now accumulated in lakes or seas, nor to those generated by ordinary volcanic action. the members of both these divisions of rocks agree in being highly crystalline and destitute of organic remains. the rocks of one division have been called plutonic, comprehending all the granites and certain porphyries, which are nearly allied in some of their characters to volcanic formations. the members of the other class are stratified and often slaty, and have been called by some the _crystalline schists_, in which group are included gneiss, micaceous-schist (or mica-slate), hornblende-schist, statuary marble, the finer kinds of roofing slate, and other rocks afterwards to be described. as it is admitted that nothing strictly analogous to these crystalline productions can now be seen in the progress of formation on the earth's surface, it will naturally be asked, on what data we can find a place for them in a system of classification founded on the origin of rocks. i cannot, in reply to this question, pretend to give the student, in a few words, an intelligible account of the long chain of facts and reasonings by which geologists have been led to infer the analogy of the rocks in question to others now in progress at the surface. the result, however, may be briefly stated. all the various kinds of granite, which constitute the plutonic family, are supposed to be of igneous origin, but to have been formed under great pressure, at considerable depths in the earth, or sometimes, perhaps, under a certain weight of incumbent water. like the lava of volcanos, they have been melted, and have afterwards cooled and crystallized, but with extreme slowness, and under conditions very different from those of bodies cooling in the open air. hence they differ from the volcanic rocks, not only by their more crystalline texture, but also by the absence of tuffs and breccias, which are the products of eruptions at the earth's surface, or beneath seas of inconsiderable depth. they differ also by the absence of pores or cellular cavities, to which the expansion of the entangled gases gives rise in ordinary lava. although granite has often pierced through other strata, it has rarely, if ever, been observed to rest upon them, as if it had overflowed. but as this is continually the case with the volcanic rocks, they have been styled, from this peculiarity, "overlying" by dr. macculloch; and mr. necker has proposed the term "underlying" for the granites, to designate the opposite mode in which they almost invariably present themselves. _metamorphic, or stratified crystalline rocks._--the fourth and last great division of rocks are the crystalline strata and slates, or schists, called gneiss, mica-schist, clay-slate, chlorite-schist, marble, and the like, the origin of which is more doubtful than that of the other three classes. they contain no pebbles, or sand, or scoriæ, or angular pieces of imbedded stone, and no traces of organic bodies, and they are often as crystalline as granite, yet are divided into beds, corresponding in form and arrangement to those of sedimentary formations, and are therefore said to be stratified. the beds sometimes consist of an alternation of substances varying in colour, composition, and thickness, precisely as we see in stratified fossiliferous deposits. according to the huttonian theory, which i adopt as most probable, and which will be afterwards more fully explained, the materials of these strata were originally deposited from water in the usual form of sediment, but they were subsequently so altered by subterranean heat, as to assume a new texture. it is demonstrable, in some cases at least, that such a complete conversion has actually taken place, fossiliferous strata having exchanged an earthy for a highly crystalline texture for a distance of a quarter of a mile from their contact with granite. in some cases, dark limestones, replete with shells and corals, have been turned into white statuary marble, and hard clays into slates called mica-schist and hornblende-schist, all signs of organic bodies having been obliterated. although we are in a great degree ignorant of the precise nature of the influence exerted in these cases, yet it evidently bears some analogy to that which volcanic heat and gases are known to produce; and the action may be conveniently called plutonic, because it appears to have been developed in those regions where plutonic rocks are generated, and under similar circumstances of pressure and depth in the earth. whether hot water or steam permeating stratified masses, or electricity, or any other causes have co-operated to produce the crystalline texture, may be matter of speculation, but it is clear that the plutonic influence has sometimes pervaded entire mountain masses of strata. in accordance with the hypothesis above alluded to, i proposed in the first edition of the principles of geology ( ), the term "metamorphic" for the altered strata, a term derived from +meta+, meta, _trans_, and +morphê+, morphe, _forma_. hence there are four great classes of rocks considered in reference to their origin,--the aqueous, the volcanic, the plutonic, and the metamorphic. in the course of this work it will be shown, that portions of each of these four distinct classes have originated at many successive periods. they have all been produced contemporaneously, and may even now be in the progress of formation. it is not true, as was formerly supposed, that all granites, together with the crystalline or metamorphic strata, were first formed, and therefore entitled to be called "primitive," and that the aqueous and volcanic rocks were afterwards superimposed, and should, therefore, rank as secondary in the order of time. this idea was adopted in the infancy of the science, when all formations, whether stratified or unstratified, earthy or crystalline, with or without fossils, were alike regarded as of aqueous origin. at that period it was naturally argued, that the foundation must be older than the superstructure; but it was afterwards discovered, that this opinion was by no means in every instance a legitimate deduction from facts; for the inferior parts of the earth's crust have often been modified, and even entirely changed, by the influence of volcanic and other subterranean causes, while superimposed formations have not been in the slightest degree altered. in other words, the destroying and renovating processes have given birth to new rocks below, while those above, whether crystalline or fossiliferous, have remained in their ancient condition. even in cities, such as venice and amsterdam, it cannot be laid down as universally true, that the upper parts of each edifice, whether of brick or marble, are more modern than the foundations on which they rest, for these often consist of wooden piles, which may have rotted and been replaced one after the other, without the least injury to the buildings above; meanwhile, these may have required scarcely any repair, and may have been constantly inhabited. so it is with the habitable surface of our globe, in its relation to large masses of rock immediately below: it may continue the same for ages, while subjacent materials, at a great depth, are passing from a solid to a fluid state, and then reconsolidating, so as to acquire a new texture. as all the crystalline rocks may, in some respects, be viewed as belonging to one great family, whether they be stratified or unstratified, plutonic or metamorphic, it will often be convenient to speak of them by one common name. it being now ascertained, as above stated, that they are of very different ages, sometimes newer than the strata called secondary, the term primary, which was formerly used for the whole, must be abandoned, as it would imply a manifest contradiction. it is indispensable, therefore, to find a new name, one which must not be of chronological import, and must express, on the one hand, some peculiarity equally attributable to granite and gneiss (to the plutonic as well as the _altered_ rocks), and, on the other, must have reference to characters in which those rocks differ, both from the volcanic and from the _unaltered_ sedimentary strata. i proposed in the principles of geology (first edition, vol. iii.), the term "hypogene" for this purpose, derived from +hypo+, _under_, and +ginomai+, _to be_, or _to be born_; a word implying the theory that granite, gneiss, and the other crystalline formations are alike _nether-formed_ rocks, or rocks which have not assumed their present form and structure at the surface. this occurs in the lowest place in the order of superposition. even in regions such as the alps, where some masses of granite and gneiss can be shown to be of comparatively modern date, belonging, for example, to the period hereafter to be described as tertiary, they are still _underlying_ rocks. they never repose on the volcanic or trappean formations, nor on strata containing organic remains. they are _hypogene_, as "being under" all the rest. from what has now been said, the reader will understand that each of the four great classes of rocks may be studied under two distinct points of view; first, they may be studied simply as mineral masses deriving their origin from particular causes, and having a certain composition, form, and position in the earth's crust, or other characters both positive and negative, such as the presence or absence of organic remains. in the second place, the rocks of each class may be viewed as a grand chronological series of monuments, attesting a succession of events in the former history of the globe and its living inhabitants. i shall accordingly proceed to treat of each family of rocks; first, in reference to those characters which are not chronological, and then in particular relation to the several periods when they were formed. footnotes: [ -a] see principles of geology, by the author, index, "nile," "rivers," &c. [ -a] see p. . [ -b] see geograph. journ. vol. iv. p. . chapter ii. aqueous rocks--their composition and forms of stratification. mineral composition of strata--arenaceous rocks--argillaceous--calcareous--gypsum--forms of stratification--original horizontality--thinning out--diagonal arrangement--ripple mark. in pursuance of the arrangement explained in the last chapter, we shall begin by examining the aqueous or sedimentary rocks, which are for the most part distinctly stratified, and contain fossils. we may first study them with reference to their mineral composition, external appearance, position, mode of origin, organic contents, and other characters which belong to them as aqueous formations, independently of their age, and we may afterwards consider them chronologically or with reference to the successive geological periods when they originated. i have already given an outline of the data which led to the belief that the stratified and fossiliferous rocks were originally deposited under water; but, before entering into a more detailed investigation, it will be desirable to say something of the ordinary materials of which such strata are composed. these may be said to belong principally to three divisions, the arenaceous, the argillaceous, and the calcareous, which are formed respectively of sand, clay, and carbonate of lime. of these, the arenaceous, or sandy masses, are chiefly made up of siliceous or flinty grains; the argillaceous, or clayey, of a mixture of siliceous matter, with a certain proportion, about a fourth in weight, of aluminous earth; and, lastly, the calcareous rocks or limestones consist of carbonic acid and lime. _arenaceous or siliceous rocks._--to speak first of the sandy division: beds of loose sand are frequently met with, of which the grains consist entirely of silex, which term comprehends all purely siliceous minerals, as quartz and common flint. quartz is silex in its purest form; flint usually contains some admixture of alumine and oxide of iron. the siliceous grains in sand are usually rounded, as if by the action of running water. sandstone is an aggregate of such grains, which often cohere together without any visible cement, but more commonly are bound together by a slight quantity of siliceous or calcareous matter, or by iron or clay. pure siliceous rocks may be known by not effervescing when a drop of nitric, sulphuric, or other acid is applied to them, or by the grains not being readily scratched or broken by ordinary pressure. in nature there is every intermediate gradation, from perfectly loose sand, to the hardest sandstone. in _micaceous sandstones_ mica is very abundant; and the thin silvery plates into which that mineral divides, are often arranged in layers parallel to the planes of stratification, giving a slaty or laminated texture to the rock. when sandstone is coarse-grained, it is usually called _grit_. if the grains are rounded, and large enough to be called pebbles, it becomes a _conglomerate_, or _pudding-stone_, which may consist of pieces of one or of many different kinds of rock. a conglomerate, therefore, is simply gravel bound together by a cement. _argillaceous rocks._--clay, strictly speaking, is a mixture of silex or flint with a large proportion, usually about one fourth, of alumine, or argil; but, in common language, any earth which possesses sufficient ductility, when kneaded up with water, to be fashioned like paste by the hand, or by the potter's lathe, is called a _clay_; and such clays vary greatly in their composition, and are, in general, nothing more than mud derived from the decomposition or wearing down of various rocks. the purest clay found in nature is porcelain clay, or kaolin, which results from the decomposition of a rock composed of felspar and quartz, and it is almost always mixed with quartz.[ -a] _shale_ has also the property, like clay, of becoming plastic in water: it is a more solid form of clay, or argillaceous matter, condensed by pressure. it usually divides into irregular laminæ. one general character of all argillaceous rocks is to give out a peculiar, earthy odour when breathed upon, which is a test of the presence of alumine, although it does not belong to pure alumine, but, apparently, to the combination of that substance with oxide of iron.[ -b] _calcareous rocks._--this division comprehends those rocks which, like chalk, are composed chiefly of lime and carbonic acid. shells and corals are also formed of the same elements, with the addition of animal matter. to obtain pure lime it is necessary to calcine these calcareous substances, that is to say, to expose them to heat of sufficient intensity to drive off the carbonic acid, and other volatile matter, without vitrifying or melting the lime itself. white chalk is often pure carbonate of lime; and this rock, although usually in a soft and earthy state, is sometimes sufficiently solid to be used for building, and even passes into a _compact_ stone, or a stone of which the separate parts are so minute as not to be distinguishable from each other by the naked eye. many limestones are made up entirely of minute fragments of shells and coral, or of calcareous sand cemented together. these last might be called "calcareous sandstones;" but that term is more properly applied to a rock in which the grains are partly calcareous and partly siliceous, or to quartzose sandstones, having a cement of carbonate of lime. the variety of limestone called "oolite" is composed of numerous small egg-like grains, resembling the roe of a fish, each of which has usually a small fragment of sand as a nucleus, around which concentric layers of calcareous matter have accumulated. any limestone which is sufficiently hard to take a fine polish is called _marble_. many of these are fossiliferous; but statuary marble, which is also called saccharine limestone, as having a texture resembling that of loaf-sugar, is devoid of fossils, and is in many cases a member of the metamorphic series. _siliceous limestone_ is an intimate mixture of carbonate of lime and flint, and is harder in proportion as the flinty matter predominates. the presence of carbonate of lime in a rock may be ascertained by applying to the surface a small drop of diluted sulphuric, nitric, or muriatic acids, or strong vinegar; for the lime, having a greater chemical affinity for any one of these acids than for the carbonic, unites immediately with them to form new compounds, thereby becoming a sulphate, nitrate, or muriate of lime. the carbonic acid, when thus liberated from its union with the lime, escapes in a gaseous form, and froths up or effervesces as it makes its way in small bubbles through the drop of liquid. this effervescence is brisk or feeble in proportion as the limestone is pure or impure, or, in other words, according to the quantity of foreign matter mixed with the carbonate of lime. without the aid of this test, the most experienced eye cannot always detect the presence of carbonate of lime in rocks. the above-mentioned three classes of rocks, the siliceous, argillaceous, and calcareous, pass continually into each other, and rarely occur in a perfectly separate and pure form. thus it is an exception to the general rule to meet with a limestone as pure as ordinary white chalk, or with clay as aluminous as that used in cornwall for porcelain, or with sand so entirely composed of siliceous grains as the white sand of alum bay in the isle of wight, or sandstone so pure as the grit of fontainebleau, used for pavement in france. more commonly we find sand and clay, or clay and marl, intermixed in the same mass. when the sand and clay are each in considerable quantity, the mixture is called _loam_. if there is much calcareous matter in clay it is called _marl_; but this term has unfortunately been used so vaguely, as often to be very ambiguous. it has been applied to substances in which there is no lime; as, to that red loam usually called red marl in certain parts of england. agriculturists were in the habit of calling any soil a marl, which, like true marl, fell to pieces readily on exposure to the air. hence arose the confusion of using this name for soils which, consisting of loam, were easily worked by the plough, though devoid of lime. _marl slate_ bears the same relation to marl which shale bears to clay, being a calcareous shale. it is very abundant in some countries, as in the swiss alps. argillaceous or marly limestone is also of common occurrence. there are few other kinds of rock which enter so largely into the composition of sedimentary strata as to make it necessary to dwell here on their characters. i may, however, mention two others,--magnesian limestone or dolomite, and gypsum. _magnesian limestone_ is composed of carbonate of lime and carbonate of magnesia; the proportion of the latter amounting in some cases to nearly one half. it effervesces much more slowly and feebly with acids than common limestone. in england this rock is generally of a yellowish colour; but it varies greatly in mineralogical character, passing from an earthy state to a white compact stone of great hardness. _dolomite_, so common in many parts of germany and france, is also a variety of magnesian limestone, usually of a granular texture. _gypsum._--gypsum is a rock composed of sulphuric acid, lime, and water. it is usually a soft whitish-yellow rock, with a texture resembling that of loaf-sugar, but sometimes it is entirely composed of lenticular crystals. it is insoluble in acids, and does not effervesce like chalk and dolomite, because it does not contain carbonic acid gas, or fixed air, the lime being already combined with sulphuric acid, for which it has a stronger affinity than for any other. anhydrous gypsum is a rare variety, into which water does not enter as a component part. gypseous marl is a mixture of gypsum and marl. alabaster is a granular and compact variety of gypsum found in masses large enough to be used in sculpture and architecture. it is sometimes a pure snow-white substance, as that of volterra in tuscany, well known as being carved for works of art in florence and leghorn. it is a softer stone than marble, and more easily wrought. _forms of stratification._--a series of strata sometimes consists of one of the above rocks, sometimes of two or more in alternating beds. thus, in the coal districts of england, for example, we often pass through several beds of sandstone, some of finer, others of coarser grain, some white, others of a dark colour, and below these, layers of shale and sandstone or beds of shale, divisible into leaf-like laminæ, and containing beautiful impressions of plants. then again we meet with beds of pure and impure coal, alternating with shales and sandstones, and underneath the whole, perhaps, are calcareous strata, or beds of limestone, filled with corals and marine shells, each bed distinguishable from another by certain fossils, or by the abundance of particular species of shells or zoophytes. this alternation of different kinds of rock produces the most distinct stratification; and we often find beds of limestone and marl, conglomerate and sandstone, sand and clay, recurring again and again, in nearly regular order, throughout a series of many hundred strata. the causes which may produce these phenomena are various, and have been fully discussed in my treatise on the modern changes of the earth's surface.[ -a] it is there seen that rivers flowing into lakes and seas are charged with sediment, varying in quantity, composition, colour, and grain according to the seasons; the waters are sometimes flooded and rapid, at other periods low and feeble; different tributaries, also, draining peculiar countries and soils, and therefore charged with peculiar sediment, are swollen at distinct periods. it was also shown that the waves of the sea and currents undermine the cliffs during wintry storms, and sweep away the materials into the deep, after which a season of tranquillity succeeds, when nothing but the finest mud is spread by the movements of the ocean over the same submarine area. it is not the object of the present work to give a description of these operations, repeated as they are, year after year, and century after century; but i may suggest an explanation of the manner in which some micaceous sandstones have originated, those in which we see innumerable thin layers of mica dividing layers of fine quartzose sand. i observed the same arrangement of materials in recent mud deposited in the estuary of la roche st. bernard in brittany, at the mouth of the loire. the surrounding rocks are of gneiss, which, by its waste, supplies the mud: when this dries at low water, it is found to consist of brown laminated clay, divided by thin seams of mica. the separation of the mica in this case, or in that of micaceous sandstones, may be thus understood. if we take a handful of quartzose sand, mixed with mica, and throw it into a clear running stream, we see the materials immediately sorted by the water, the grains of quartz falling almost directly to the bottom, while the plates of mica take a much longer time to reach the bottom, and are carried farther down the stream. at the first instant the water is turbid, but immediately after the flat surfaces of the plates of mica are seen alone reflecting a silvery light, as they descend slowly, to form a distinct micaceous lamina. the mica is the heavier mineral of the two; but it remains longer suspended, owing to its great extent of surface. it is easy, therefore, to perceive that where such mud is acted upon by a river or tidal current, the thin plates of mica will be carried farther, and not deposited in the same places as the grains of quartz; and since the force and velocity of the stream varies from time to time, layers of mica or of sand will be thrown down successively on the same area. _original horizontality._--it has generally been said that the upper and under surfaces of strata, or the planes of stratification, as they are termed, are parallel. although this is not strictly true, they make an approach to parallelism, for the same reason that sediment is usually deposited at first in nearly horizontal layers. the reason of this arrangement can by no means be attributed to an original evenness or horizontality in the bed of the sea; for it is ascertained that in those places where no matter has been recently deposited, the bottom of the ocean is often as uneven as that of the dry land, having in like manner its hills, valleys, and ravines. yet if the sea should sink, or the water be removed near the mouth of a large river where a delta has been forming, we should see extensive plains of mud and sand laid dry, which, to the eye, would appear perfectly level, although, in reality, they would slope gently from the land towards the sea. this tendency in newly-formed strata to assume a horizontal position arises principally from the motion of the water, which forces along particles of sand or mud at the bottom, and causes them to settle in hollows or depressions, where they are less exposed to the force of a current than when they are resting on elevated points. the velocity of the current and the motion of the superficial waves diminish from the surface downwards, and are least in those depressions where the water is deepest. [illustration: fig. . cross section.] a good illustration of the principle here alluded to may be sometimes seen in the neighbourhood of a volcano, when a section, whether natural or artificial, has laid open to view a succession of various-coloured layers of sand and ashes, which have fallen in showers upon uneven ground. thus let a b (fig. .) be two ridges, with an intervening valley. these original inequalities of the surface have been gradually effaced by beds of sand and ashes _c_, _d_, _e_, the surface at e being quite level. it will be seen that although the materials of the first layers have accommodated themselves in a great degree to the shape of the ground a b, yet each bed is thickest at the bottom. at first a great many particles would be carried by their own gravity down the steep sides of a and b, and others would afterwards be blown by the wind as they fell off the ridges, and would settle in the hollow, which would thus become more and more effaced as the strata accumulated from _c_ to _e_. this levelling operation may perhaps be rendered more clear to the student by supposing a number of parallel trenches to be dug in a plain of moving sand, like the african desert, in which case the wind would soon cause all signs of these trenches to disappear, and the surface would be as uniform as before. now, water in motion can exert this levelling power on similar materials more easily than air, for almost all stones lose in water more than a third of the weight which they have in air, the specific gravity of rocks being in general as - / when compared to that of water, which is estimated at . but the buoyancy of sand or mud would be still greater in the sea, as the density of salt water exceeds that of fresh. yet, however uniform and horizontal may be the surface of new deposits in general, there are still many disturbing causes, such as eddies in the water, and currents moving first in one and then in another direction, which frequently cause irregularities. we may sometimes follow a bed of limestone, shale, or sandstone, for a distance of many hundred yards continuously; but we generally find at length that each individual stratum thins out, and allows the beds which were previously above and below it to meet. if the materials are coarse, as in grits and conglomerates, the same beds can rarely be traced many yards without varying in size, and often coming to an end abruptly. (see fig. .) [illustration: fig. . section of strata of sandstone, grit, and conglomerate.] [illustration: fig. . section of sand at sandy hill, near biggleswade, bedfordshire. height feet. (greensand formation.)] _diagonal or cross stratification._--there is also another phenomenon of frequent occurrence. we find a series of larger strata, each of which is composed of a number of minor layers placed obliquely to the general planes of stratification. to this diagonal arrangement the name of "false or cross stratification" has been given. thus in the annexed section (fig. .) we see seven or eight large beds of loose sand, yellow and brown, and the lines _a_, _b_, _c_, mark some of the principal planes of stratification, which are nearly horizontal. but the greater part of the subordinate laminæ do not conform to these planes, but have often a steep slope, the inclination being sometimes towards opposite points of the compass. when the sand is loose and incoherent, as in the case here represented, the deviation from parallelism of the slanting laminæ cannot possibly be accounted for by any re-arrangement of the particles acquired during the consolidation of the rock. in what manner then can such irregularities be due to original deposition? we must suppose that at the bottom of the sea, as well as in the beds of rivers, the motions of waves, currents, and eddies often cause mud, sand, and gravel to be thrown down in heaps on particular spots, instead of being spread out uniformly over a wide area. sometimes, when banks are thus formed, currents may cut passages through them, just as a river forms its bed. suppose the bank a (fig. .) to be thus formed with a steep sloping side, and the water being in a tranquil state, the layer of sediment no. . is thrown down upon it, conforming nearly to its surface. afterwards the other layers, , , , may be deposited in succession, so that the bank b c d is formed. if the current then increases in velocity, it may cut away the upper portion of this mass down to the dotted line _e_ (fig. .), and deposit the materials thus removed farther on, so as to form the layers , , , . we have now the bank b c d e (fig. .), of which the surface is almost level, and on which the nearly horizontal layers, , , , may then accumulate. it was shown in fig. . that the diagonal layers of successive strata may sometimes have an opposite slope. this is well seen in some cliffs of loose sand on the suffolk coast. a portion of one of these is represented in fig. ., where the layers, of which there are about six in the thickness of an inch, are composed of quartzose grains. this arrangement may have been due to the altered direction of the tides and currents in the same place. [illustration: fig. . cross section.] [illustration: fig. . cross section.] [illustration: fig. . cliff between mismer and dunwich.] [illustration: fig. . section from monte calvo to the sea by the valley of magnan, near nice. a. dolomite and sandstone. (greensand formation?) _a_, _b_, _d_. beds of gravel and sand. _c._ fine marl and sand of st. madeleine, with marine shells.] the description above given of the slanting position of the minor layers constituting a single stratum is in certain cases applicable on a much grander scale to masses several hundred feet thick, and many miles in extent. a fine example may be seen at the base of the maritime alps near nice. the mountains here terminate abruptly in the sea, so that a depth of many hundred fathoms is often found within a stone's throw of the beach, and sometimes a depth of feet within half a mile. but at certain points, strata of sand, marl, or conglomerate, intervene between the shore and the mountains, as in the annexed fig. ., where a vast succession of slanting beds of gravel and sand may be traced from the sea to monte calvo, a distance of no less than miles in a straight line. the dip of these beds is remarkably uniform, being always southward or towards the mediterranean, at an angle of about °. they are exposed to view in nearly vertical precipices, varying from to feet in height, which bound the valley through which the river magnan flows. although in a general view, the strata appear to be parallel and uniform, they are nevertheless found, when examined closely, to be wedge-shaped, and to thin out when followed for a few hundred feet or yards, so that we may suppose them to have been thrown down originally upon the side of a steep bank, where a river or alpine torrent discharged itself into a deep and tranquil sea, and formed a delta, which advanced gradually from the base of monte calvo to a distance of miles from the original shore. if subsequently this part of the alps and bed of the sea were raised feet, the coast would acquire its present configuration, the delta would emerge, and a deep channel might then be cut through it by a river. it is well known that the torrents and streams, which now descend from the alpine declivities to the shore, bring down annually, when the snow melts, vast quantities of shingle and sand, and then, as they subside, fine mud, while in summer they are nearly or entirely dry; so that it may be safely assumed, that deposits like those of the valley of the magnan, consisting of coarse gravel alternating with fine sediment, are still in progress at many points, as, for instance, at the mouth of the var. they must advance upon the mediterranean in the form of great shoals terminating in a steep talus; such being the original mode of accumulation of all coarse materials conveyed into deep water, especially where they are composed in great part of pebbles, which cannot be transported to indefinite distances by currents of moderate velocity. by inattention to facts and inferences of this kind, a very exaggerated estimate has sometimes been made of the supposed depth of the ancient ocean. there can be no doubt, for example, that the strata _a_, fig. ., or those nearest to monte calvo, are older than those indicated by _b_, and these again were formed before _c_; but the vertical depth of gravel and sand in any one place cannot be proved to amount even to feet, although it may perhaps be much greater, yet probably never exceeding at any point or feet. but were we to assume that all the strata were once horizontal, and that their present dip or inclination was due to subsequent movements, we should then be forced to conclude, that a sea miles deep had been filled up with alternate layers of mud and pebbles thrown down one upon another. in the locality now under consideration, situated a few miles to the west of nice, there are many geological data, the details of which cannot be given in this place, all leading to the opinion, that when the deposit of the magnan was formed, the shape and outline of the alpine declivities and the shore greatly resembled what we now behold at many points in the neighbourhood. that the beds, a, b, c, d, are of comparatively modern date is proved by this fact, that in seams of loamy marl intervening between the pebbly beds are fossil shells, half of which belong to species now living in the mediterranean. [illustration: fig. . slab of ripple-marked (new red) sandstone from cheshire.] _ripple mark._--the ripple mark, so common on the surface of sandstones of all ages (see fig. .), and which is so often seen on the sea-shore at low tide, seems to originate in the drifting of materials along the bottom of the water, in a manner very similar to that which may explain the inclined layers above described. this ripple is not entirely confined to the beach between high and low water mark, but is also produced on sands which are constantly covered by water. similar undulating ridges and furrows may also be sometimes seen on the surface of drift snow and blown sand. the following is the manner in which i once observed the motion of the air to produce this effect on a large extent of level beach, exposed at low tide near calais. clouds of fine white sand were blown from the neighbouring dunes, so as to cover the shore, and whiten a dark level surface of sandy mud, and this fresh covering of sand was beautifully rippled. on levelling all the small ridges and furrows of this ripple over an area of several yards square, i saw them perfectly restored in about ten minutes, the general direction of the ridges being always at right angles to that of the wind. the restoration began by the appearance here and there of small detached heaps of sand, which soon lengthened and joined together, so as to form long sinuous ridges with intervening furrows. each ridge had one side slightly inclined, and the other steep; the lee-side being always steep, as _b, c,--d, e_; the windward-side a gentle slope, as _a, b,--c, d_, fig. . when a gust of wind blew with sufficient force to drive along a cloud of sand, all the ridges were seen to be in motion at once, each encroaching on the furrow before it, and, in the course of a few minutes, filling the place which the furrows had occupied. the mode of advance was by the continual drifting of grains of sand up the slopes _a b_ and _c d_, many of which grains, when they arrived at _b_ and _d_, fell over the scarps _b c_ and _d e_, and were under shelter from the wind; so that they remained stationary, resting, according to their shape and momentum, on different parts of the descent, and a few only rolling to the bottom. in this manner each ridge was distinctly seen to move slowly on as often as the force of the wind augmented. occasionally part of a ridge, advancing more rapidly than the rest, overtook the ridge immediately before it, and became confounded with it, thus causing those bifurcations and branches which are so common, and two of which are seen in the slab, fig. . we may observe this configuration in sandstones of all ages, and in them also, as now on the sea-coast, we may often detect two systems of ripples interfering with each other; one more ancient and half effaced, and a newer one, in which the grooves and ridges are more distinct, and in a different direction. this crossing of two sets of ripples arises from a change of wind, and the new direction in which the waves are thrown on the shore. [illustration: fig. . sketch of ripples.] the ripple mark is usually an indication of a sea-beach, or of water from to feet deep, for the agitation caused by waves even during storms extends to a very slight depth. to this rule, however, there are some exceptions, and recent ripple marks have been observed at the depth of or feet. it has also been ascertained that currents or large bodies of water in motion may disturb mud and sand at the depth of or even feet.[ -a] footnotes: [ -a] the kaolin of china consists of · parts of silex, · of alumine, · of lime, and · of water (w. phillips, mineralogy, p. .); but other porcelain clays differ materially, that of cornwall being composed, according to boase of nearly equal parts of silica and alumine, with per cent. of magnesia. (phil. mag. vol. x. .) [ -b] see w. phillips's mineralogy, "alumine." [ -a] consult index to principles of geology, "stratification," "currents," "deltas," "water," &c. [ -a] siau. edin. new phil. journ. vol. xxxi.; and darwin, volc. islands, p. . chapter iii. arrangement of fossils in strata--freshwater and marine. successive deposition indicated by fossils--limestones formed of corals and shells proofs of gradual increase of strata derived from fossils--serpula attached to spatangus--wood bored by teredina--tripoli and semi-opal formed of infusoria--chalk derived principally from organic bodies--distinction of freshwater from marine formations--genera of freshwater and land shells--rules for recognizing marine testacea--gyrogonite and chara--freshwater fishes--alternation of marine and freshwater deposits--lym-fiord. having in the last chapter considered the forms of stratification so far as they are determined by the arrangement of inorganic matter, we may now turn our attention to the manner in which organic remains are distributed through stratified deposits. we should often be unable to detect any signs of stratification or of successive deposition, if particular kinds of fossils did not occur here and there at certain depths in the mass. at one level, for example, univalve shells of some one or more species predominate; at another, bivalve shells; and at a third, corals; while in some formations we find layers of vegetable matter, commonly derived from land plants, separating strata. it may appear inconceivable to a beginner how mountains, several thousand feet thick, can have become filled with fossils from top to bottom; but the difficulty is removed, when he reflects on the origin of stratification, as explained in the last chapter, and allows sufficient time for the accumulation of sediment. he must never lose sight of the fact that, during the process of deposition, each separate layer was once the uppermost, and covered immediately by the water in which aquatic animals lived. each stratum in fact, however far it may now lie beneath the surface, was once in the state of shingle, or loose sand or soft mud at the bottom of the sea, in which shells and other bodies easily became enveloped. by attending to the nature of these remains, we are often enabled to determine whether the deposition was slow or rapid, whether it took place in a deep or shallow sea, near the shore or far from land, and whether the water was salt, brackish, or fresh. some limestones consist almost exclusively of corals, and in many cases it is evident that the present position of each fossil zoophyte has been determined by the manner in which it grew originally. the axis of the coral, for example, if its natural growth is erect, still remains at right angles to the plane of stratification. if the stratum be now horizontal, the round spherical heads of certain species continue uppermost, and their points of attachment are directed downwards. this arrangement is sometimes repeated throughout a great succession of strata. from what we know of the growth of similar zoophytes in modern reefs, we infer that the rate of increase was extremely slow, and some of the fossils must have flourished for ages like forest trees, before they attained so large a size. during these ages, the water remained clear and transparent, for such corals cannot live in turbid water. [illustration: fig. . fossil _gryphæa_, covered both on the outside and inside with fossil serpulæ.] in like manner, when we see thousands of full-grown shells dispersed every where throughout a long series of strata, we cannot doubt that time was required for the multiplication of successive generations; and the evidence of slow accumulation is rendered more striking from the proofs, so often discovered, of fossil bodies having lain for a time on the floor of the ocean after death before they were imbedded in sediment. nothing, for example, is more common than to see fossil oysters in clay, with serpulæ, or barnacles (acorn-shells), or corals, and other creatures, attached to the inside of the valves, so that the mollusk was certainly not buried in argillaceous mud the moment it died. there must have been an interval during which it was still surrounded with clear water, when the testacea, now adhering to it, grew from an embryo state to full maturity. attached shells which are merely external, like some of the serpulæ (_a_) in the annexed figure (fig. .), may often have grown upon an oyster or other shell while the animal within was still living; but if they are found on the inside, it could only happen after the death of the inhabitant of the shell which affords the support. thus, in fig. ., it will be seen that two serpulæ have grown on the interior, one of them exactly on the place where the adductor muscle of the _gryphæa_ (a kind of oyster) was fixed. some fossil shells, even if simply attached to the _outside_ of others, bear full testimony to the conclusion above alluded to, namely, that an interval elapsed between the death of the creature to whose shell they adhere, and the burial of the same in mud or sand. the sea-urchins or _echini_, so abundant in white chalk, afford a good illustration. it is well known that these animals, when living, are invariably covered with numerous spines, which serve as organs of motion, and are supported by rows of tubercles, which last are only seen after the death of the sea-urchin, when the spines have dropped off. in fig. . a living species of _spatangus_, common on our coast, is represented with one half of its shell stripped of the spines. in fig. . a fossil of the same genus from the white chalk of england shows the naked surface which the individuals of this family exhibit when denuded of their bristles. the full-grown _serpula_, therefore, which now adheres externally, could not have begun to grow till the _spatangus_ had died, and the spines were detached. [illustration: fig. . _serpula_ attached to a fossil _spatangus_ from the chalk.] [illustration: fig. . recent _spatangus_ with the spines removed from one side. _b._ spine and tubercles, nat. size. _a._ the same magnified.] [illustration: fig. . _a._ _echinus_ from the chalk, with lower valve of the _crania_ attached. _b._ upper valve of the _crania_ detached.] now the series of events here attested by a single fossil may be carried a step farther. thus, for example, we often meet with a sea-urchin in the chalk (see fig. .), which has fixed to it the lower valve of a _crania_, a genus of bivalve mollusca. the upper valve (_b_, fig. .) is almost invariably wanting, though occasionally found in a perfect state of preservation in white chalk at some distance. in this case, we see clearly that the sea-urchin first lived from youth to age, then died and lost its spines, which were carried away. then the young _crania_ adhered to the bared shell, grew and perished in its turn; after which the upper valve was separated from the lower before the _echinus_ became enveloped in chalky mud. it may be well to mention one more illustration of the manner in which single fossils may sometimes throw light on a former state of things, both in the bed of the ocean and on some adjoining land. we meet with many fragments of wood bored by ship-worms at various depths in the clay on which london is built. entire branches and stems of trees, several feet in length, are sometimes dug out, drilled all over by the holes of these borers, the tubes and shells of the mollusk still remaining in the cylindrical hollows. in fig. . _e_, a representation is given of a piece of recent wood pierced by the _teredo navalis_, or common ship-worm, which destroys wooden piles and ships. when the cylindrical tube _d_ has been extracted from the wood, a shell is seen at the larger extremity, composed of two pieces, as shown at _c_. in like manner, a piece of fossil wood (_a_, fig. .) has been perforated by an animal of a kindred but extinct genus, called _teredina_ by lamarck. the calcareous tube of this mollusk was united and as it were soldered on to the valves of the shell (_b_), which therefore cannot be detached from the tube, like the valves of the recent _teredo_. the wood in this fossil specimen is now converted into a stony mass, a mixture of clay and lime; but it must once have been buoyant and floating in the sea, when the _teredinæ_ lived upon it, perforating it in all directions. again, before the infant colony settled upon the drift wood, the branch of a tree must have been floated down to the sea by a river, uprooted, perhaps, by a flood, or torn off and cast into the waves by the wind: and thus our thoughts are carried back to a prior period, when the tree grew for years on dry land, enjoying a fit soil and climate. [ illustrations: fossil and recent wood drilled by perforating mollusca. fig. . _a_. fossil wood from london clay, bored by _teredina_. _b_. shell and tube of _teredina personata_, the right-hand figure the ventral, the left the dorsal view. fig. . _e_. recent wood bored by _teredo_. _d_. shell and tube of _teredo navalis_, from the same. _c_. anterior and posterior view of the valves of same detached from the tube.] it has been already remarked that there are rocks in the interior of continents, at various depths in the earth, and at great heights above the sea, almost entirely made up of the remains of zoophytes and testacea. such masses may be compared to modern oyster-beds and coral reefs; and, like them, the rate of increase must have been extremely gradual. but there are a variety of stony deposits in the earth's crust, now proved to have been derived from plants and animals, of which the organic origin was not suspected until of late years, even by naturalists. great surprise was therefore created by the recent discovery of professor ehrenberg of berlin, that a certain kind of siliceous stone, called tripoli, was entirely composed of millions of the remains of organic beings, which the prussian naturalist refers to microscopic infusoria, but which most others now believe to be plants. they abound in freshwater lakes and ponds in england and other countries, and are termed diatomaceæ by those naturalists who believe in their vegetable origin. the substance alluded to has long been well known in the arts, being used in the form of powder for polishing stones and metals. it has been procured, among other places, from bilin, in bohemia, where a single stratum, extending over a wide area, is no less than feet thick. this stone, when examined with a powerful microscope, is found to consist of the siliceous plates or frustules of the above-mentioned diatomaceæ, united together without any visible cement. it is difficult to convey an idea of their extreme minuteness; but ehrenberg estimates that in the bilin tripoli there are , millions of individuals of the _gaillonella distans_ (see fig. .) in every cubic inch, which weighs about grains, or about millions in a single grain. at every stroke, therefore, that we make with this polishing powder, several millions, perhaps tens of millions, of perfect fossils are crushed to atoms. [ illustrations: these figures are magnified nearly times, except the lower figure of _g. ferruginea_ (fig. . _a_), which is magnified times. fig. . _bacillaria vulgaris?_ fig. . _gaillonella distans._ fig. . _gaillonella ferruginea._] [ illustrations: fragment of semi-opal from the great bed of tripoli, bilin. fig. . natural size. fig. . the same magnified, showing circular articulations of a species of _gaillonella_, and spiculæ of _spongilla_.] the remains of these diatomaceæ are of pure silex, and their forms are various, but very marked and constant in particular genera and species. thus, in the family _bacillaria_ (see fig. .), the fossils preserved in tripoli are seen to exhibit the same divisions and transverse lines which characterize the living species of kindred form. with these, also, the siliceous spiculæ or internal supports of the freshwater sponge, or _spongilla_ of lamarck, are sometimes intermingled (see the needle-shaped bodies in fig. .). these flinty cases and spiculæ, although hard, are very fragile, breaking like glass, and are therefore admirably adapted, when rubbed, for wearing down into a fine powder fit for polishing the surface of metals. besides the tripoli, formed exclusively of the fossils above described, there occurs in the upper part of the great stratum at bilin another heavier and more compact stone, a kind of semi-opal, in which innumerable parts of diatomaceæ and spiculæ of the _spongilla_ are filled with, and cemented together by, siliceous matter. it is supposed that the siliceous remains of the most delicate diatomaceæ have been dissolved by water, and have thus given rise to this opal in which the more durable fossils are preserved like insects in amber. this opinion is confirmed by the fact that the organic bodies decrease in number and sharpness of outline in proportion as the opaline cement increases in quantity. in the bohemian tripoli above described, as in that of planitz in saxony, the species of diatomaceæ (or infusoria, as termed by ehrenberg) are freshwater; but in other countries, as in the tripoli of the isle of france, they are of marine species, and they all belong to formations of the _tertiary_ period, which will be spoken of hereafter. a well-known substance, called bog-iron ore, often met with in peat-mosses, has also been shown by ehrenberg to consist of innumerable articulated threads, of a yellow ochre colour, composed partly of flint and partly of oxide of iron. these threads are the cases of a minute microscopic body, called _gaillonella ferruginea_ (fig. .). [ illustrations: _cytheridæ_ and _foraminifera_ from the chalk. fig. . _cythere_, müll. _cytherina_, lam. fig. . portion of _nodosaria_. fig. . _cristellaria rotulata._ fig. . _rosalina._] it is clear that much time must have been required for the accumulation of strata to which countless generations of diatomaceæ have contributed their remains; and these discoveries lead us naturally to suspect that other deposits, of which the materials have usually been supposed to be inorganic, may in reality have been derived from microscopic organic bodies. that this is the case with the white chalk, has often been imagined, this rock having been observed to abound in a variety of marine fossils, such as shells, echini, corals, sponges, crustacea, and fishes. mr. lonsdale, on examining, in oct. , in the museum of the geological society of london, portions of white chalk from different parts of england, found, on carefully pulverizing them in water, that what appear to the eye simply as white grains were, in fact, well preserved fossils. he obtained above a thousand of these from each pound weight of chalk, some being fragments of minute corallines, others entire foraminifera and cytheridæ. the annexed drawings will give an idea of the beautiful forms of many of these bodies. the figures _a_ _a_ represent their natural size, but, minute as they seem, the smallest of them, such as _a_, fig. ., are gigantic in comparison with the cases of diatomaceæ before mentioned. it has, moreover, been lately discovered that the chambers into which these foraminifera are divided are actually often filled with thousands of well-preserved organic bodies, which abound in every minute grain of chalk, and are especially apparent in the white coating of flints, often accompanied by innumerable needle-shaped spiculæ of sponges. after reflecting on these discoveries, we are naturally led on to conjecture that, as the formless cement in the semi-opal of bilin has been derived from the decomposition of animal and vegetable remains, so also even those parts of chalk flints in which no organic structure can be recognized may nevertheless have constituted a part of microscopic animalcules. "the dust we tread upon was once alive!"--byron. how faint an idea does this exclamation of the poet convey of the real wonders of nature! for here we discover proofs that the calcareous and siliceous dust of which hills are composed has not only been once alive, but almost every particle, albeit invisible to the naked eye, still retains the organic structure which, at periods of time incalculably remote, was impressed upon it by the powers of life. _freshwater and marine fossils._--strata, whether deposited in salt or fresh water, have the same forms; but the imbedded fossils are very different in the two cases, because the aquatic animals which frequent lakes and rivers are distinct from those inhabiting the sea. in the northern part of the isle of wight a formation of marl and limestone, more than feet thick, occurs, in which the shells are principally, if not all, of extinct species. yet we recognize their freshwater origin, because they are of the same genera as those now abounding in ponds and lakes, either in our own country or in warmer latitudes. in many parts of france, as in auvergne, for example, strata of limestone, marl, and sandstone are found, hundreds of feet thick, which contain exclusively freshwater and land shells, together with the remains of terrestrial quadrupeds. the number of land shells scattered through some of these freshwater deposits is exceedingly great; and there are districts in germany where the rocks scarcely contain any other fossils except snail-shells (_helices_); as, for instance, the limestone on the left bank of the rhine, between mayence and worms, at oppenheim, findheim, budenheim, and other places. in order to account for this phenomenon, the geologist has only to examine the small deltas of torrents which enter the swiss lakes when the waters are low, such as the newly-formed plain where the kander enters the lake of thun. he there sees sand and mud strewed over with innumerable dead land shells, which have been brought down from valleys in the alps in the preceding spring, during the melting of the snows. again, if we search the sands on the borders of the rhine, in the lower part of its course, we find countless land shells mixed with others of species belonging to lakes, stagnant pools, and marshes. these individuals have been washed away from the alluvial plains of the great river and its tributaries, some from mountainous regions, others from the low country. although freshwater formations are often of great thickness, yet they are usually very limited in area when compared to marine deposits, just as lakes and estuaries are of small dimensions in comparison with seas. we may distinguish a freshwater formation, first, by the absence of many fossils almost invariably met with in marine strata. for example, there are no sea-urchins, no corals, and scarcely any zoophytes; no chambered shells, such as the nautilus, nor microscopic foraminifera. but it is chiefly by attending to the forms of the mollusca that we are guided in determining the point in question. in a freshwater deposit, the number of individual shells is often as great, if not greater, than in a marine stratum; but there is a smaller variety of species and genera. this might be anticipated from the fact that the genera and species of recent freshwater and land shells are few when contrasted with the marine. thus, the genera of true mollusca according to blainville's system, excluding those of extinct species and those without shells, amount to about in number, of which the terrestrial and freshwater genera scarcely form more than a sixth.[ -a] [illustration: fig. . _cyclas obovata_; fossil. hants.] [illustration: fig. . _cyrena consobrina_; fossil. grays, essex.] [illustration: fig. . _anodonta cordierii_; fossil. paris.] [illustration: fig. . _anodonta latimarginatus_; recent. bahia.] [illustration: fig. . _unio littoralis_; recent. auvergne.] almost all bivalve shells, or those of acephalous mollusca, are marine, about ten only out of ninety genera being freshwater. among these last, the four most common forms, both recent and fossil, are _cyclas_, _cyrena_, _unio_, and _anodonta_ (see figures); the two first and two last of which are so nearly allied as to pass into each other. [illustration: fig. . _gryphæa incurva_, sow. (_g. arcuata_, lam.) upper valve. lias.] lamarck divided the bivalve mollusca into the _dimyary_, or those having two large muscular impressions in each valve, as _a b_ in the cyclas, fig. ., and the _monomyary_, such as the oyster and scallop, in which there is only one of these impressions, as is seen in fig. . now, as none of these last, or the unimuscular bivalves, are freshwater, we may at once presume a deposit in which we find any of them to be marine. [illustration: fig. . _planorbis euomphalus_; fossil. isle of wight.] [illustration: fig. . _lymnea longiscata_; fossil. hants.] [illustration: fig. . _paludina lenta_; fossil. hants.] the univalve shells most characteristic of freshwater deposits are, _planorbis_, _lymnea_, and _paludina_. (see figures.) but to these are occasionally added _physa_, _succinea_, _ancylus_, _valvata_, _melanopsis_, _melania_, and _neritina_. (see figures.) [illustration: fig. . _succinea amphibia_; fossil. loess, rhine.] [illustration: fig. . _ancylus elegans_; fossil. hants.] [illustration: fig. . _valvata_; fossil. grays, essex.] [illustration: fig. . _physa hypnorum_; recent.] [illustration: fig. . _auricula_; recent. ava.] [illustration: fig. . _melania inquinata._ paris basin.] [illustration: fig. . _physa columnaris._ paris basin.] [illustration: fig. . _melanopsis buccinoidea_; recent. asia.] in regard to one of these, the _ancylus_ (fig. .), mr. gray observes that it sometimes differs in no respect from the marine _siphonaria_, except in the animal. the shell, however, of the _ancylus_ is usually thinner.[ -a] [illustration: fig. . _neritina globulus._ paris basin.] [illustration: fig. . _nerita granulosa._ paris basin.] some naturalists include _neritina_ (fig. .) and the marine _nerita_ (fig. .) in the same genus, it being scarcely possible to distinguish the two by good generic characters. but, as a general rule, the fluviatile species are smaller, smoother, and more globular than the marine; and they have never, like the _neritæ_, the inner margin of the outer lip toothed or crenulated. (see fig. .) [illustration: fig. . _cerithium cinctum._ paris basin.] a few genera, among which _cerithium_ (fig. .) is the most abundant, are common both to rivers and the sea, having species peculiar to each. other genera, like _auricula_ (fig. .), are amphibious, frequenting marshes, especially near the sea. [illustration: fig. . _helix turonensis._ faluns, touraine.] [illustration: fig. . _cyclostoma elegans._ loess.] [illustration: fig. . _pupa tridens._ loess.] [illustration: fig. . _clausilia bidens._ loess.] [illustration: fig. . _bulimus lubricus._ loess, rhine.] the terrestrial shells are all univalves. the most abundant genera among these, both in a recent and fossil state, are _helix_ (fig. .), _cyclostoma_ (fig. .), _pupa_ (fig. .), _clausilia_ (fig. .), _bulimus_ (fig. .), and _achatina_; which two last are nearly allied and pass into each other. [illustration: fig. . _ampullaria glauca_, from the jumna.] the _ampullaria_ (fig. .) is another genus of shells, inhabiting rivers and ponds in hot countries. many fossil species have been referred to this genus, but they have been found chiefly in marine formations, and are suspected by some conchologists to belong to _natica_ and other marine genera. all univalve shells of land and freshwater species, with the exception of _melanopsis_ (fig. .), and _achatina_, which has a slight indentation, have entire mouths; and this circumstance may often serve as a convenient rule for distinguishing freshwater from marine strata; since, if any univalves occur of which the mouths are not entire, we may presume that the formation is marine. the aperture is said to be entire in such shells as the _ampullaria_ and the land shells (figs. - .), when its outline is not interrupted by an indentation or notch, such as that seen at _b_ in _ancillaria_ (fig. .); or is not prolonged into a canal, as that seen at _a_ in _pleurotoma_ (fig. .). [illustration: fig. . _pleurotoma rotata._ subap. hills, italy.] [illustration: fig. . _ancillaria subulata._ london clay.] the mouths of a large proportion of the marine univalves have these notches or canals, and almost all such species are carnivorous; whereas nearly all testacea having entire mouths, are plant-eaters; whether the species be marine, freshwater, or terrestrial. there is, however, one genus which affords an occasional exception to one of the above rules. the _cerithium_ (fig. .), although provided with a short canal, comprises some species which inhabit salt, others brackish, and others fresh water, and they are said to be all plant-eaters. among the fossils very common in freshwater deposits are the shells of _cypris_, a minute crustaceous animal, having a shell much resembling that of the bivalve mollusca.[ -a] many minute living species of this genus swarm in lakes and stagnant pools in great britain; but their shells are not, if considered separately, conclusive as to the freshwater origin of a deposit, because the majority of species in another kindred genus of the same order, the _cytherina_ of lamarck (see above, fig. . p. .), inhabit salt water; and, although the animal differs slightly, the shell is scarcely distinguishable from that of the _cypris_. the seed-vessels and stems of _chara_, a genus of aquatic plants, are very frequent in freshwater strata. these seed-vessels were called, before their true nature was known, gyrogonites, and were supposed to be foraminiferous shells. (see fig. . _a._) the _charæ_ inhabit the bottom of lakes and ponds, and flourish mostly where the water is charged with carbonate of lime. their seed-vessels are covered with a very tough integument, capable of resisting decomposition; to which circumstance we may attribute their abundance in a fossil state. the annexed figure (fig. .) represents a branch of one of many new species found by professor amici in the lakes of northern italy. the seed-vessel in this plant is more globular than in the british _charæ_, and therefore more nearly resembles in form the extinct fossil species found in england, france, and other countries. the stems, as well as the seed-vessels, of these plants occur both in modern shell marl and in ancient freshwater formations. they are generally composed of a large tube surrounded by smaller tubes; the whole stem being divided at certain intervals by transverse partitions or joints. (see _b_, fig. .) [illustration: fig. . _chara medicaginula_; fossil. isle of wight. _a._ seed-vessel. magnified diameters. _b._ stem, magnified.] [illustration: fig. . _chara elastica_; recent. italy. _a._ sessile seed vessel between the division of the leaves of the female plant. _b._ transverse section of a branch, with five seed-vessels magnified, seen from below upwards.] it is not uncommon to meet with layers of vegetable matter, impressions of leaves, and branches of trees, in strata containing freshwater shells; and we also find occasionally the teeth and bones of land quadrupeds, of species now unknown. the manner in which such remains are occasionally carried by rivers into lakes, especially during floods, has been fully treated of in the "principles of geology."[ -a] the remains of fish are occasionally useful in determining the freshwater origin of strata. certain genera, such as carp, perch, pike, and loach (_cyprinus_, _perca_, _esox_, and _cobitis_), as also _lebias_, being peculiar to freshwater. other genera contain some freshwater and some marine species, as _cottus_, _mugil_, and _anguilla_, or eel. the rest are either common to rivers and the sea, as the salmon; or are exclusively characteristic of salt water. the above observations respecting fossil fishes are applicable only to the more modern or tertiary deposits; for in the more ancient rocks the forms depart so widely from those of existing fishes, that it is very difficult, at least in the present state of science, to derive any positive information from ichthyolites respecting the element in which strata were deposited. the alternation of marine and freshwater formations, both on a small and large scale, are facts well ascertained in geology. when it occurs on a small scale, it may have arisen from the alternate occupation of certain spaces by river water and the sea; for in the flood season the river forces back the ocean and freshens it over a large area, depositing at the same time its sediment; after which the salt water again returns, and, on resuming its former place, brings with it sand, mud, and marine shells. there are also lagoons at the mouths of many rivers, as the nile and mississippi, which are divided off by bars of sand from the sea, and which are filled with salt and fresh water by turns. they often communicate exclusively with the river for months, years, or even centuries; and then a breach being made in the bar of sand, they are for long periods filled with salt water. the lym-fiord in jutland offers an excellent illustration of analogous changes; for, in the course of the last thousand years, the western extremity of this long frith, which is miles in length, including its windings, has been four times fresh and four times salt, a bar of sand between it and the ocean having been as often formed and removed. the last irruption of salt water happened in , when the north sea entered, killing all the freshwater shells, fish, and plants; and from that time to the present, the sea-weed _fucus vesiculosus_, together with oysters and other marine mollusca, have succeeded the _cyclas_, _lymnea_, _paludina_, and _charæ_.[ -a] but changes like these in the lym-fiord, and those before mentioned as occurring at the mouths of great rivers, will only account for some cases of marine deposits of partial extent resting on freshwater strata. when we find, as in the south-east of england, a great series of freshwater beds, feet in thickness, resting upon marine formations and again covered by other rocks, such as the cretaceous, more than feet thick, and of deep-sea origin, we shall find it necessary to seek for a different explanation of the phenomena.[ -b] footnotes: [ -a] see synoptic table in blainville's malacologie. [ -a] gray, phil. trans., , p. . [ -a] for figures of recent species, see below, p. ., and figs. of fossils, see p. . [ -a] see index of principles, "fossilization." [ -a] see principles, index, "lym-fiord." [ -b] see below, chap. xviii., on the wealden. chapter iv. consolidation of strata and petrifaction of fossils. chemical and mechanical deposits--cementing together of particles--hardening by exposure to air--concretionary nodules--consolidating effects of pressure--mineralization of organic remains--impressions and casts how formed--fossil wood--göppert's experiments--precipitation of stony matter most rapid where putrefaction is going on--source of lime in solution--silex derived from decomposition of felspar--proofs of the lapidification of some fossils soon after burial, of others when much decayed. having spoken in the preceding chapters of the characters of sedimentary formations, both as dependent on the deposition of inorganic matter and the distribution of fossils, i may next treat of the consolidation of stratified rocks, and the petrifaction of imbedded organic remains. _chemical and mechanical deposits._--a distinction has been made by geologists between deposits of a chemical, and those of a mechanical, origin. by the latter name are designated beds of mud, sand, or pebbles produced by the action of running water, also accumulations of stones and scoriæ thrown out by a volcano, which have fallen into their present place by the force of gravitation. but the matter which forms a chemical deposit has not been mechanically suspended in water, but in a state of solution until separated by chemical action. in this manner carbonate of lime is often precipitated upon the bottom of lakes and seas in a solid form, as may be well seen in many parts of italy, where mineral springs abound, and where the calcareous stone, called travertin, is deposited. in these springs the lime is usually held in solution by an excess of carbonic acid, or by heat if it be a hot spring, until the water, on issuing from the earth, cools or loses part of its acid. the calcareous matter then falls down in a solid state, encrusting shells, fragments of wood and leaves, and binding them together.[ -a] in coral reefs, large masses of limestone are formed by the stony skeletons of zoophytes; and these, together with shells, become cemented together by carbonate of lime, part of which is probably furnished to the sea-water by the decomposition of dead corals. even shells of which the animals are still living, on these reefs, are very commonly found to be encrusted over with a hard coating of limestone.[ -b] if sand and pebbles are carried by a river into the sea, and these are bound together immediately by carbonate of lime, the deposit may be described as of a mixed origin, partly chemical, and partly mechanical. now, the remarks already made in chapter ii. on the original horizontality of strata are strictly applicable to mechanical deposits, and only partially to those of a mixed nature. such as are purely chemical may be formed on a very steep slope, or may even encrust the vertical walls of a fissure, and be of equal thickness throughout; but such deposits are of small extent, and for the most part confined to veinstones. _cementing of particles._--it is chiefly in the case of calcareous rocks that solidification takes place at the time of deposition. but there are many deposits in which a cementing process comes into operation long afterwards. we may sometimes observe, where the water of ferruginous or calcareous springs has flowed through a bed of sand or gravel, that iron or carbonate of lime has been deposited in the interstices between the grains or pebbles, so that in certain places the whole has been bound together into a stone, the same set of strata remaining in other parts loose and incoherent. proofs of a similar cementing action are seen in a rock at kelloway in wiltshire. a peculiar band of sandy strata, belonging to the group called oolite by geologists, may be traced through several counties, the sand being for the most part loose and unconsolidated, but becoming stony near kelloway. in this district there are numerous fossil shells which have decomposed, having for the most part left only their casts. the calcareous matter hence derived has evidently served, at some former period, as a cement to the siliceous grains of sand, and thus a solid sandstone has been produced. if we take fragments of many other argillaceous grits, retaining the casts of shells, and plunge them into dilute muriatic or other acid, we see them immediately changed into common sand and mud; the cement of lime, derived from the shells, having been dissolved by the acid. traces of impressions and casts are often extremely faint. in some loose sands of recent date we meet with shells in so advanced a stage of decomposition as to crumble into powder when touched. it is clear that water percolating such strata may soon remove the calcareous matter of the shell; and, unless circumstances cause the carbonate of lime to be again deposited, the grains of sand will not be cemented together; in which case no memorial of the fossil will remain. the absence of organic remains from many aqueous rocks may be thus explained; but we may presume that in many of them no fossils were ever imbedded, as there are extensive tracts on the bottoms of existing seas even of moderate depth on which no fragment of shell, coral, or other living creature can be detected by dredging. on the other hand, there are depths where the zero of animal life has been approached; as, for example, in the mediterranean, at the depth of about fathoms, according to the researches of prof. e. forbes. in the Ægean sea a deposit of yellowish mud of a very uniform character, and closely resembling chalk, is going on in regions below fathoms, and this formation must be wholly devoid of organic remains.[ -a] in what manner silex and carbonate of lime may become widely diffused in small quantities through the waters which permeate the earth's crust will be spoken of presently, when the petrifaction of fossil bodies is considered; but i may remark here that such waters are always passing in the case of thermal springs from hotter to colder parts of the interior of the earth; and as often as the temperature of the solvent is lowered, mineral matter has a tendency to separate from it and solidify. thus a stony cement is often supplied to any sand, pebbles, or fragmentary mixture. in some conglomerates, like the pudding-stone of hertfordshire, pebbles of flint and grains of sand are united by a siliceous cement so firmly, that if a block be fractured the rent passes as readily through the pebbles as through the cement. it is probable that many strata became solid at the time when they emerged from the waters in which they were deposited, and when they first formed a part of the dry land. a well-known fact seems to confirm this idea: by far the greater number of the stones used for building and road-making are much softer when first taken from the quarry than after they have been long exposed to the air; and these, when once dried, may afterwards be immersed for any length of time in water without becoming soft again. hence it is found desirable to shape the stones which are to be used in architecture while they are yet soft and wet, and while they contain their "quarry-water," as it is called; also to break up stone intended for roads when soft, and then leave it to dry in the air for months that it may harden. such induration may perhaps be accounted for by supposing the water, which penetrates the minutest pores of rocks, to deposit, on evaporation, carbonate of lime, iron, silex, and other minerals previously held in solution, and thereby to fill up the pores partially. these particles, on crystallizing, would not only be themselves deprived of freedom of motion, but would also bind together other portions of the rock which before were loosely aggregated. on the same principle wet sand and mud become as hard as stone when frozen; because one ingredient of the mass, namely, the water, has crystallized, so as to hold firmly together all the separate particles of which the loose mud and sand were composed. dr. macculloch mentions a sandstone in skye, which may be moulded like dough when first found; and some simple minerals, which are rigid and as hard as glass in our cabinets, are often flexible and soft in their native beds; this is the case with asbestos, sahlite, tremolite, and chalcedony, and it is reported also to happen in the case of the beryl.[ -a] the marl recently deposited at the bottom of lake superior, in north america, is soft, and often filled with freshwater shells; but if a piece be taken up and dried, it becomes so hard that it can only be broken by a smart blow of the hammer. if the lake therefore was drained, such a deposit would be found to consist of strata of marlstone, like that observed in many ancient european formations, and like them containing freshwater shells.[ -b] it is probable that some of the heterogeneous materials which rivers transport to the sea may at once set under water, like the artificial mixture called pozzolana, which consists of fine volcanic sand charged with about per cent. of oxide of iron, and the addition of a small quantity of lime. this substance hardens, and becomes a solid stone in water, and was used by the romans in constructing the foundations of buildings in the sea. consolidation in these cases is brought about by the action of chemical affinity on finely comminuted matter previously suspended in water. after deposition similar particles seem to exert a mutual attraction on each other, and congregate together in particular spots, forming lumps, nodules, and concretions. thus in many argillaceous deposits there are calcareous balls, or spherical concretions, ranged in layers parallel to the general stratification; an arrangement which took place after the shale or marl had been thrown down in successive laminæ; for these laminæ are often traced in the concretions, remaining parallel to those of the surrounding unconsolidated rock. (see fig. .) such nodules of limestone have often a shell or other foreign body in the centre.[ -a] [illustration: fig. . calcareous nodules in lias.] among the most remarkable examples of concretionary structure are those described by professor sedgwick as abounding in the magnesian limestone of the north of england. the spherical balls are of various sizes, from that of a pea to a diameter of several feet, and they have both a concentric and radiated structure, while at the same time the laminæ of original deposition pass uninterruptedly through them. in some cliffs this limestone resembles a great irregular pile of cannon balls. some of the globular masses have their centre in one stratum, while a portion of their exterior passes through to the stratum above or below. thus the larger spheroid in the annexed section (fig. .) passes from the stratum _b_ upwards into _a_. in this instance we must suppose the deposition of a series of minor layers, first forming the stratum _b_, and afterwards the incumbent stratum _a_; then a movement of the particles took place, and the carbonates of lime and magnesia separated from the more impure and mixed matter forming the still unconsolidated parts of the stratum. crystallization, beginning at the centre, must have gone on forming concentric coats, around the original nucleus without interfering with the laminated structure of the rock. [illustration: fig. . spheroidal concretions in magnesian limestone.] when the particles of rocks have been thus re-arranged by chemical forces, it is sometimes difficult or impossible to ascertain whether certain lines of division are due to original deposition or to the subsequent aggregation of similar particles. thus suppose three strata of grit, a, b, c, are charged unequally with calcareous matter, and that b is the most calcareous. if consolidation takes place in b, the concretionary action may spread upwards into a part of a, where the carbonate of lime is more abundant than in the rest; so that a mass, _d_, _e_, _f_, forming a portion of the superior stratum, becomes united with b into one solid mass of stone. the original line of division _d_, _e_, being thus effaced, the line _d_, _f_, would generally be considered as the surface of the bed b, though not strictly a true plane of stratification. [illustration: fig. . block section.] _pressure and heat._--when sand and mud sink to the bottom of a deep sea, the particles are not pressed down by the enormous weight of the incumbent ocean; for the water, which becomes mingled with the sand and mud, resists pressure with a force equal to that of the column of fluid above. the same happens in regard to organic remains which are filled with water under great pressure as they sink, otherwise they would be immediately crushed to pieces and flattened. nevertheless, if the materials of a stratum remain in a yielding state, and do not set or solidify, they will be gradually squeezed down by the weight of other materials successively heaped upon them, just as soft clay or loose sand on which a house is built may give way. by such downward pressure particles of clay, sand, and marl, may become packed into a smaller space, and be made to cohere together permanently. analogous effects of condensation may arise when the solid parts of the earth's crust are forced in various directions by those mechanical movements afterwards to be described, by which strata have been bent, broken, and raised above the level of the sea. rocks of more yielding materials must often have been forced against others previously consolidated, and, thus compressed, may have acquired a new structure. a recent discovery may help us to comprehend how fine sediment derived from the detritus of rocks may be solidified by mere pressure. the graphite or "black lead" of commerce having become very scarce, mr. brockedon contrived a method by which the dust of the purer portions of the mineral found in borrowdale might be recomposed into a mass as dense and compact as native graphite. the powder of graphite is first carefully prepared and freed from air, and placed under a powerful press on a strong steel die, with air-tight fittings. it is then struck several blows, each of a power of tons; after which operation the powder is so perfectly solidified that it can be cut for pencils, and exhibits when broken the same texture as native graphite. but the action of heat at various depths in the earth is probably the most powerful of all causes in hardening sedimentary strata. to this subject i shall refer again when treating of the metamorphic rocks, and of the slaty and jointed structure. _mineralization of organic remains._--the changes which fossil organic bodies have undergone since they were first imbedded in rocks, throw much light on the consolidation of strata. fossil shells in some modern deposits have been scarcely altered in the course of centuries, having simply lost a part of their animal matter. but in other cases the shell has disappeared, and left an impression only of its exterior, or a cast of its interior form, or thirdly, a cast of the shell itself, the original matter of which has been removed. these different forms of fossilization may easily be understood if we examine the mud recently thrown out from a pond or canal in which there are shells. if the mud be argillaceous, it acquires consistency on drying, and on breaking open a portion of it we find that each shell has left impressions of its external form. if we then remove the shell itself, we find within a solid nucleus of clay, having the form of the interior of the shell. this form is often very different from that of the outer shell. thus a cast such as _a_, fig. ., commonly called a fossil screw, would never be suspected by an inexperienced conchologist to be the internal shape of the fossil univalve, _b_, fig. . nor should we have imagined at first sight that the shell _a_ and the cast _b_, fig. ., were different parts of the same fossil. the reader will observe, in the last-mentioned figure (_b_, fig. .), that an empty space shaded dark, which the _shell itself_ once occupied, now intervenes between the enveloping stone and the cast of the smooth interior of the whorls. in such cases the shell has been dissolved and the component particles removed by water percolating the rock. if the nucleus were taken out a hollow mould would remain, on which the external form of the shell with its tubercles and striæ, as seen in _a_, fig. ., would be seen embossed. now if the space alluded to between the nucleus and the impression, instead of being left empty, has been filled up with calcareous spar, flint, pyrites, or other mineral, we then obtain from the mould an exact cast both of the external and internal form of the original shell. in this manner silicified casts of shells have been formed; and if the mud or sand of the nucleus happen to be incoherent, or soluble in acid, we can then procure in flint an empty shell, which in shape is the exact counterpart of the original. this cast may be compared to a bronze statue, representing merely the superficial form, and not the internal organization; but there is another description of petrifaction by no means uncommon, and of a much more wonderful kind, which may be compared to certain anatomical models in wax, where not only the outward forms and features, but the nerves, blood-vessels, and other internal organs are also shown. thus we find corals, originally calcareous, in which not only the general shape, but also the minute and complicated internal organization are retained in flint. [illustration: fig. . _phasianella heddingtonensis_, and cast of the same. coral rag.] [illustration: fig. . _trochus anglicus_ and cast. lias.] such a process of petrifaction is still more remarkably exhibited in fossil wood, in which we often perceive not only the rings of annual growth, but all the minute vessels and medullary rays. many of the minute pores and fibres of plants, and even those spiral vessels which in the living vegetable can only be discovered by the microscope, are preserved. among many instances, i may mention a fossil tree, feet in length, found at gosforth near newcastle, in sandstone strata associated with coal. by cutting a transverse slice so thin as to transmit light, and magnifying it about fifty-five times, the texture seen in fig. . is exhibited. a texture equally minute and complicated has been observed in the wood of large trunks of fossil trees found in the craigleith quarry near edinburgh, where the stone was not in the slightest degree siliceous, but consisted chiefly of carbonate of lime, with oxide of iron, alumina, and carbon. the parallel rows of vessels here seen are the rings of annual growth, but in one part they are imperfectly preserved, the wood having probably decayed before the mineralizing matter had penetrated to that portion of the tree. [illustration: fig. . texture of a tree from the coal strata, magnified. (witham.) transverse section.] in attempting to explain the process of petrifaction in such cases, we may first assume that strata are very generally permeated by water charged with minute portions of calcareous, siliceous, and other earths in solution. in what manner they become so impregnated will be afterwards considered. if an organic substance is exposed in the open air to the action of the sun and rain, it will in time putrefy, or be dissolved into its component elements, which consist chiefly of oxygen, hydrogen, and carbon. these will readily be absorbed by the atmosphere or be washed away by rain, so that all vestiges of the dead animal or plant disappear. but if the same substances be submerged in water, they decompose more gradually; and if buried in earth, still more slowly, as in the familiar example of wooden piles or other buried timber. now, if as fast as each particle is set free by putrefaction in a fluid or gaseous state, a particle equally minute of carbonate of lime, flint, or other mineral, is at hand and ready to be precipitated, we may imagine this inorganic matter to take the place just before left unoccupied by the organic molecule. in this manner a cast of the interior of certain vessels may first be taken, and afterwards the more solid walls of the same may decay and suffer a like transmutation. yet when the whole is lapidified, it may not form one homogeneous mass of stone or metal. some of the original ligneous, osseous, or other organic elements may remain mingled in certain parts, or the lapidifying substance itself may be differently coloured at different times, or so crystallized as to reflect light differently, and thus the texture of the original body may be faithfully exhibited. the student may perhaps ask whether, on chemical principles, we have any ground to expect that mineral matter will be thrown down precisely in those spots where organic decomposition is in progress? the following curious experiments may serve to illustrate this point. professor göppert of breslau attempted recently to imitate the natural process of petrifaction. for this purpose he steeped a variety of animal and vegetable substances in waters, some holding siliceous, others calcareous, others metallic matter in solution. he found that in the period of a few weeks, or even days, the organic bodies thus immersed were mineralized to a certain extent. thus, for example, thin vertical slices of deal, taken from the scotch fir (_pinus sylvestris_), were immersed in a moderately strong solution of sulphate of iron. when they had been thoroughly soaked in the liquid for several days they were dried and exposed to a red-heat until the vegetable matter was burnt up and nothing remained but an oxide of iron, which was found to have taken the form of the deal so exactly that casts even of the dotted vessels peculiar to this family of plants were distinctly visible under the microscope. another accidental experiment has been recorded by mr. pepys in the geological transactions.[ -a] an earthen pitcher containing several quarts of sulphate of iron had remained undisturbed and unnoticed for about a twelvemonth in the laboratory. at the end of this time when the liquor was examined an oily appearance was observed on the surface, and a yellowish powder, which proved to be sulphur, together with a quantity of small hairs. at the bottom were discovered the bones of several mice in a sediment consisting of small grains of pyrites, others of sulphur, others of crystallized green sulphate of iron, and a black muddy oxide of iron. it was evident that some mice had accidentally been drowned in the fluid, and by the mutual action of the animal matter and the sulphate of iron on each other, the metallic sulphate had been deprived of its oxygen; hence the pyrites and the other compounds were thrown down. although the mice were not mineralized, or turned into pyrites, the phenomenon shows how mineral waters, charged with sulphate of iron, may be deoxydated on coming in contact with animal matter undergoing putrefaction, so that atom after atom of pyrites may be precipitated, and ready, under favourable circumstances, to replace the oxygen, hydrogen, and carbon into which the original body would be resolved. the late dr. turner observes, that when mineral matter is in a "nascent state," that is to say, just liberated from a previous state of chemical combination, it is most ready to unite with other matter, and form a new chemical compound. probably the particles or atoms just set free are of extreme minuteness, and therefore move more freely, and are more ready to obey any impulse of chemical affinity. whatever be the cause, it clearly follows, as before stated, that where organic matter newly imbedded in sediment is decomposing, there will chemical changes take place most actively. an analysis was lately made of the water which was flowing off from the rich mud deposited by the hooghly river in the delta of the ganges after the annual inundation. this water was found to be highly charged with carbonic acid gas holding lime in solution.[ -b] now if newly-deposited mud is thus proved to be permeated by mineral matter in a state of solution, it is not difficult to perceive that decomposing organic bodies, naturally imbedded in sediment, may as readily become petrified as the substances artificially immersed by professor göppert in various fluid mixtures. it is well known that the water of springs, or that which is continually percolating the earth's crust, is rarely free from a slight admixture either of iron, carbonate of lime, sulphur, silica, potash, or some other earthy, alkaline, or metallic ingredient. hot springs in particular are copiously charged with one or more of these elements; and it is only in their waters that silex is found in abundance. in certain cases, therefore, especially in volcanic regions, we may imagine the flint of silicified wood and corals to have been supplied by the waters of thermal springs. in other instances, as in tripoli and chalk-flint, it may have been derived in great part, if not wholly, from the decomposition of infusoria or diatomaceæ, sponges, and other bodies. but even if this be granted, we have still to inquire whence a lake or the ocean can be constantly replenished with the calcareous and siliceous matter so abundantly withdrawn from it by the secretions of these zoophytes. in regard to carbonate of lime there is no difficulty, because not only are calcareous springs very numerous, but even rain-water has the power of dissolving a minute portion of the calcareous rocks over which it flows. hence marine corals and mollusca may be provided by rivers with the materials of their shells and solid supports. but pure silex, even when reduced to the finest powder and boiled, is insoluble in water, except at very high temperatures. nevertheless dr. turner has well explained, in an essay on the chemistry of geology[ -a], how the decomposition of felspar may be a source of silex in solution. he has remarked that the siliceous earth, which constitutes more than half the bulk of felspar, is intimately combined with alumine, potash, and some other elements. the alkaline matter of the felspar has a chemical affinity for water, as also for the carbonic acid which is more or less contained in the waters of most springs. the water therefore carries away alkaline matter, and leaves behind a clay consisting of alumine and silica. but this residue of the decomposed mineral, which in its purest state is called porcelain clay, is found to contain a part only of the silica which existed in the original felspar. the other part, therefore, must have been dissolved and removed; and this can be accounted for in two ways; first, because silica when combined with an alkali is soluble in water; secondly, because silica in what is technically called its nascent state is also soluble in water. hence an endless supply of silica is afforded to rivers and the waters of the sea. for the felspathic rocks are universally distributed, constituting, as they do, so large a proportion of the volcanic, plutonic, and metamorphic formations. even where they chance to be absent in mass, they rarely fail to occur in the superficial gravel or alluvial deposits of the basin of every large river. the disintegration of mica also, another mineral which enters largely into the composition of granite and various sandstones, may yield silica which may be dissolved in water, for nearly half of this mineral consists of silica, combined with alumine, potash, and about a tenth part of iron. the oxidation of this iron in the air is the principal cause of the waste of mica. we have still, however, much to learn before the conversion of fossil bodies into stone is fully understood. some phenomena seem to imply that the mineralization must proceed with considerable rapidity, for stems of a soft and succulent character, and of a most perishable nature, are preserved in flint; and there are instances of the complete silicification of the young leaves of a palm-tree when just about to shoot forth, and in that state which in the west indies is called the cabbage of the palm.[ -a] it may, however, be questioned whether in such cases there may not have been some antiseptic quality in the water which retarded putrefaction, so that the soft parts of the buried substance may have remained for a long time without disintegration, like the flesh of bodies imbedded in peat. mr. stokes has pointed out examples of petrifactions in which the more perishable, and others where the more durable portions of wood are preserved. these variations, he suggests, must doubtless have depended on the time when the lapidifying mineral was introduced. thus, in certain silicified stems of palm-trees, the cellular tissue, that most destructible part, is in good condition, while all signs of the hard woody fibre have disappeared, the spaces once occupied by it being hollow or filled with agate. here, petrifaction must have commenced soon after the wood was exposed to the action of moisture, and the supply of mineral matter must then have failed, or the water must have become too much diluted before the woody fibre decayed. but when this fibre is alone discoverable, we must suppose that an interval of time elapsed before the commencement of lapidification, during which the cellular tissue was obliterated. when both structures, namely, the cellular and the woody fibre, are preserved, the process must have commenced at an early period, and continued without interruption till it was completed throughout.[ -b] footnotes: [ -a] see principles, index, "calcareous springs," &c. [ -b] ibid. "travertin," "coral reefs," &c. [ -a] report brit. ass. , p. . [ -a] dr. macculloch, syst. of geol. vol. i. p. . [ -b] princ. of geol., index, "superior lake." [ -a] de la beche, geol. researches, p. ., and geol. observer ( ), p. . [ -a] vol. i. p. . first series. [ -b] piddington, asiat. research. vol. xviii. p. . [ -a] jam. ed. new phil. journ. no. . p. . [ -a] stokes, geol. trans., vol. v. p. . second series. [ -b] ibid. chapter v. elevation of strata above the sea--horizontal and inclined stratification. why the position of marine strata, above the level of the sea, should be referred to the rising up of the land, not to the going down of the sea--upheaval of extensive masses of horizontal strata--inclined and vertical stratification--anticlinal and synclinal lines--bent strata in east of scotland--theory of folding by lateral movement--creeps--dip and strike--structure of the jura--various forms of outcrop--rocks broken by flexure--inverted position of disturbed strata--unconformable stratification--hutton and playfair on the same--fractures of strata--polished surfaces--faults--appearance of repeated alternations produced by them--origin of great faults. _land has been raised, not the sea lowered._--it has been already stated that the aqueous rocks containing marine fossils extend over wide continental tracts, and are seen in mountain chains rising to great heights above the level of the sea. hence it follows, that what is now dry land was once under water. but if we admit this conclusion, we must imagine, either that there has been a general lowering of the waters of the ocean, or that the solid rocks, once covered by water, have been raised up bodily out of the sea, and have thus become dry land. the earlier geologists, finding themselves reduced to this alternative, embraced the former opinion, assuming that the ocean was originally universal, and had gradually sunk down to its actual level, so that the present islands and continents were left dry. it seemed to them far easier to conceive that the water had gone down, than that solid land had risen upwards into its present position. it was, however, impossible to invent any satisfactory hypothesis to explain the disappearance of so enormous a body of water throughout the globe, it being necessary to infer that the ocean had once stood at whatever height marine shells might be detected. it moreover appeared clear, as the science of geology advanced, that certain spaces on the globe had been alternately sea, then land, then estuary, then sea again, and, lastly, once more habitable land, having remained in each of these states for considerable periods. in order to account for such phenomena, without admitting any movement of the land itself, we are required to imagine several retreats and returns of the ocean; and even then our theory applies merely to cases where the marine strata composing the dry land are horizontal, leaving unexplained those more common instances where strata are inclined, curved, or placed on their edges, and evidently not in the position in which they were first deposited. geologists, therefore, were at last compelled to have recourse to the other alternative, namely, the doctrine that the solid land has been repeatedly moved upwards or downwards, so as permanently to change its position relatively to the sea. there are several distinct grounds for preferring this conclusion. first, it will account equally for the position of those elevated masses of marine origin in which the stratification remains horizontal, and for those in which the strata are disturbed, broken, inclined, or vertical. secondly, it is consistent with human experience that land should rise gradually in some places and be depressed in others. such changes have actually occurred in our own days, and are now in progress, having been accompanied in some cases by violent convulsions, while in others they have proceeded so insensibly, as to have been ascertainable only by the most careful scientific observations, made at considerable intervals of time. on the other hand, there is no evidence from human experience of a lowering of the sea's level in any region, and the ocean cannot sink in one place without its level being depressed all over the globe. these preliminary remarks will prepare the reader to understand the great theoretical interest attached to all facts connected with the position of strata, whether horizontal or inclined, curved or vertical. now the first and most simple appearance is where strata of marine origin occur above the level of the sea in horizontal position. such are the strata which we meet with in the south of sicily, filled with shells for the most part of the same species as those now living in the mediterranean. some of these rocks rise to the height of more than feet above the sea. other mountain masses might be mentioned, composed of horizontal strata of high antiquity, which contain fossil remains of animals wholly dissimilar from any now known to exist. in the south of sweden, for example, near lake wener, the beds of one of the oldest of the fossiliferous deposits, namely that formerly called transition, and now silurian, by geologists, occur in as level a position as if they had recently formed part of the delta of a great river, and been left dry on the retiring of the annual floods. aqueous rocks of about the same age extend for hundreds of miles over the lake-district of north america, and exhibit in like manner a stratification nearly undisturbed. the table mountain at the cape of good hope is another example of highly elevated yet perfectly horizontal strata, no less than feet in thickness, and consisting of sandstone of very ancient date. instead of imagining that such fossiliferous rocks were always at their present level, and that the sea was once high enough to cover them, we suppose them to have constituted the ancient bed of the ocean, and that they were gradually uplifted to their present height. this idea, however startling it may at first appear, is quite in accordance, as before stated, with the analogy of changes now going on in certain regions of the globe. thus, in parts of sweden, and the shores and islands of the gulf of bothnia, proofs have been obtained that the land is experiencing, and has experienced for centuries, a slow upheaving movement. playfair argued in favour of this opinion in ; and in , von buch, after his travels in scandinavia, announced his conviction that a rising of the land was in progress. celsius and other swedish writers had, a century before, declared their belief that a gradual change had, for ages, been taking place in the relative level of land and sea. they attributed the change to a fall of the waters both of the ocean and the baltic. this theory, however, has now been refuted by abundant evidence; for the alteration of relative level has neither been universal nor every where uniform in quantity, but has amounted, in some regions, to several feet in a century, in others to a few inches; while in the southernmost part of sweden, or the province of scania, there has been actually a loss instead of a gain of land, buildings having gradually sunk below the level of the sea.[ -a] it appears, from the observations of mr. darwin and others, that very extensive regions of the continent of south america have been undergoing slow and gradual upheaval, by which the level plains of patagonia, covered with recent marine shells, and the pampas of buenos ayres, have been raised above the level of the sea.[ -b] on the other hand, the gradual sinking of the west coast of greenland, for the space of more than miles from north to south, during the last four centuries, has been established by the observations of a danish naturalist, dr. pingel. and while these proofs of continental elevation and subsidence, by slow and insensible movements, have been recently brought to light, the evidence has been daily strengthened of continued changes of level effected by violent convulsions in countries where earthquakes are frequent. there the rocks are rent from time to time, and heaved up or thrown down several feet at once, and disturbed in such a manner, that the original position of strata may, in the course of centuries, be modified to any amount. it has also been shown by mr. darwin, that, in those seas where circular coral islands and barrier reefs abound, there is a slow and continued sinking of the submarine mountains on which the masses of coral are based; while there are other areas of the south sea, where the land is on the rise, and where coral has been upheaved far above the sea-level. it would require a volume to explain to the reader the various facts which establish the reality of these movements of land, whether of elevation or depression, whether accompanied by earthquakes or accomplished slowly and without local disturbance. having treated fully of these subjects in the principles of geology[ -c], i shall assume, in the present work, that such changes are part of the actual course of nature; and when admitted, they will be found to afford a key to the interpretation of a variety of geological appearances, such as the elevation of horizontal, inclined, or disturbed marine strata, and the superposition of freshwater to marine deposits, afterwards to be described. it will also appear, in the sequel, how much light the doctrine of a continued subsidence of land may throw on the manner in which a series of strata, formed in shallow water, may have accumulated to a great thickness. the excavation of valleys also, and other effects of _denudation_, of which i shall presently treat, can alone be understood when we duly appreciate the proofs, now on record, of the prolonged rising and sinking of land, throughout wide areas. to conclude this subject, i may remind the reader, that were we to embrace the doctrine which ascribes the elevated position of marine formations, and the depression of certain freshwater strata, to oscillations in the level of the waters instead of the land, we should be compelled to admit that the ocean has been sometimes every where much shallower than at present, and at others more than three miles deeper. [illustration: fig. . vertical conglomerate and sandstone.] _inclined stratification._--the most unequivocal evidence of a change in the original position of strata is afforded by their standing up perpendicularly on their edges, which is by no means a rare phenomenon, especially in mountainous countries. thus we find in scotland, on the southern skirts of the grampians, beds of pudding-stone alternating with thin layers of fine sand, all placed vertically to the horizon. when saussure first observed certain conglomerates in a similar position in the swiss alps, he remarked that the pebbles, being for the most part of an oval shape, had their longer axes parallel to the planes of stratification (see fig. .). from this he inferred, that such strata must, at first, have been horizontal, each oval pebble having originally settled at the bottom of the water, with its flatter side parallel to the horizon, for the same reason that an egg will not stand on either end if unsupported. some few, indeed, of the rounded stones in a conglomerate occasionally afford an exception to the above rule, for the same reason that we see on a shingle beach some oval or flat-sided pebbles resting on their ends or edges; these having been forced along the bottom and against each other by a wave or current so as to settle in this position. vertical strata, when they can be traced continuously upwards or downwards for some depth, are almost invariably seen to be parts of great curves, which may have a diameter of a few yards, or of several miles. i shall first describe two curves of considerable regularity, which occur in forfarshire, extending over a country twenty miles in breadth, from the foot of the grampians to the sea near arbroath. the mass of strata here shown may be nearly feet in thickness, consisting of red and white sandstone, and various coloured shales, the beds being distinguishable into four principal groups, namely, no. . red marl or shale; no. . red sandstone, used for building; no. . conglomerate; and no. . grey paving-stone, and tile-stone, with green and reddish shale, containing peculiar organic remains. a glance at the section will show that each of the formations , , , are repeated thrice at the surface, twice with a southerly, and once with a northerly inclination or _dip_, and the beds in no. ., which are nearly horizontal, are still brought up twice by a slight curvature to the surface, once on each side of a. beginning at the north-west extremity, the tile-stones and conglomerates no. . and no. . are vertical, and they generally form a ridge parallel to the southern skirts of the grampians. the superior strata nos. . and . become less and less inclined on descending to the valley of strathmore, where the strata, having a concave bend, are said by geologists to lie in a "trough" or "basin." through the centre of this valley runs an imaginary line a, called technically a "synclinal line," where the beds, which are tilted in opposite directions, may be supposed to meet. it is most important for the observer to mark such lines, for he will perceive by the diagram, that in travelling from the north to the centre of the basin, he is always passing from older to newer beds; whereas, after crossing the line a, and pursuing his course in the same southerly direction, he is continually leaving the newer, and advancing upon older strata. all the deposits which he had before examined begin then to recur in reversed order, until he arrives at the central axis of the sidlaw hills, where the strata are seen to form an arch or _saddle_, having an _anticlinal_ line b, in the centre. on passing this line, and continuing towards the s.e., the formations , , and , are again repeated, in the same relative order of superposition, but with a northerly dip. at whiteness (see diagram) it will be seen that the inclined strata are covered by a newer deposit, _a_, in horizontal beds. these are composed of red conglomerate and sand, and are newer than any of the groups, , , , , before described, and rest _unconformably_ upon strata of the sandstone group, no. . [illustration: fig. . section of forfarshire, from n.w. to s.e., from foot of the grampians to the sea at arbroath (volcanic or trap rocks omitted). length of section twenty miles.] an example of curved strata, in which the bends or convolutions of the rock are sharper and far more numerous within an equal space, has been well described by sir james hall.[ -a] it occurs near st. abb's head, on the east coast of scotland, where the rocks consist principally of a bluish slate, having frequently a ripple-marked surface. the undulations of the beds reach from the top to the bottom of cliffs from to feet in height, and there are sixteen distinct bendings in the course of about six miles, the curvatures being alternately concave and convex upwards. [illustration: fig. . curved strata of slate near st. abb's head, berwickshire. (sir j. hall.)] [illustration: fig. . block section.] an experiment was made by sir james hall, with a view of illustrating the manner in which such strata, assuming them to have been originally horizontal, may have been forced into their present position. a set of layers of clay were placed under a weight, and their opposite ends pressed towards each other with such force as to cause them to approach more nearly together. on the removal of the weight, the layers of clay were found to be curved and folded, so as to bear a miniature resemblance to the strata in the cliffs. we must, however, bear in mind, that in the natural section or sea-cliff we only see the foldings imperfectly, one part being invisible beneath the sea, and the other, or upper portion, being supposed to have been carried away by _denudation_, or that action of water which will be explained in the next chapter. the dark lines in the accompanying plan (fig. .) represent what is actually seen of the strata in part of the line of cliff alluded to; the fainter lines, that portion which is concealed beneath the sea level, as also that which is supposed to have once existed above the present surface. [illustration: fig. . experimental set-up.] we may still more easily illustrate the effects which a lateral thrust might produce on flexible strata, by placing several pieces of differently coloured cloths upon a table, and when they are spread out horizontally, cover them with a book. then apply other books to each end, and force them towards each other. the folding of the cloths will exactly imitate those of the bent strata. (see fig. .) whether the analogous flexures in stratified rocks have really been due to similar sideway movements is a question of considerable difficulty. it will appear when the volcanic and granitic rocks are described, that some of them have, when melted, been injected forcibly into fissures, while others, already in a solid state, have been protruded upwards through the incumbent crust of the earth, by which a great displacement of flexible strata must have been caused. but we also know by the study of regions liable to earthquakes, that there are causes at work in the interior of the earth capable of producing a sinking in of the ground, sometimes very local, but sometimes extending over a wide area. the frequent repetition, or continuance throughout long periods, of such downward movements seems to imply the formation and renewal of cavities at a certain depth below the surface, whether by the removal of matter by volcanos and hot springs, or by the contraction of argillaceous rocks by heat and pressure, or any other combination of circumstances. whatever conjectures we may indulge respecting the causes, it is certain that pliable beds may, in consequence of unequal degrees of subsidence, become folded to any amount, and have all the appearance of having been compressed suddenly by a lateral thrust. the "creeps," as they are called in coal-mines, afford an excellent illustration of this fact.--first, it may be stated generally, that the excavation of coal at a considerable depth causes the mass of overlying strata to sink down bodily, even when props are left to support the roof of the mine. "in yorkshire," says mr. buddle, "three distinct subsidences were perceptible at the surface, after the clearing out of three seams of coal below, and innumerable vertical cracks were caused in the incumbent mass of sandstone and shale, which thus settled down."[ -a] the exact amount of depression in these cases can only be accurately measured where water accumulates on the surface, or a railway traverses a coal-field. [illustration: fig. . section of carboniferous strata, at wallsend, newcastle, showing "creeps." (j. buddle, esq.) horizontal length of section feet. the upper seam, or main coal, here worked out, was feet below the surface.] when a bed of coal is worked out, pillars or rectangular masses of coal are left at intervals as props to support the roof, and protect the colliers. thus in fig. ., representing a section at wallsend, newcastle, the galleries which have been excavated are represented by the white spaces _a b_, while the adjoining dark portions are parts of the original coal-seam left as props, beds of sandy clay or shale constituting the floor of the mine. when the props have been reduced in size, they are pressed down by the weight of overlying rocks (no less than feet thick) upon the shale below, which is thereby squeezed and forced up into the open spaces. now it might have been expected, that instead of the floor rising up, the ceiling would sink down, and this effect, called a "thrust," does, in fact, take place where the pavement is more solid than the roof. but it usually happens, in coal-mines, that the roof is composed of hard shale, or occasionally of sandstone, more unyielding than the foundation, which often consists of clay. even where the argillaceous substrata are hard at first, they soon become softened and reduced to a plastic state when exposed to the contact of air and water in the floor of a mine. the first symptom of a "creep," says mr. buddle, is a slight curvature at the bottom of each gallery, as at _a_, fig. .: then the pavement continuing to rise, begins to open with a longitudinal crack, as at _b_: then the points of the fractured ridge reach the roof, as at _c_; and, lastly, the upraised beds close up the whole gallery, and the broken portions of the ridge are re-united and flattened at the top, exhibiting the flexure seen at _d_. meanwhile the coal in the props has become crushed and cracked by pressure. it is also found, that below the creeps _a_, _b_, _c_, _d_, an inferior stratum, called the "metal coal," which is feet thick, has been fractured at the points _e_, _f_, _g_, _h_, and has risen, so as to prove that the upward movement, caused by the working out of the "main coal," has been propagated through a thickness of feet of argillaceous beds, which intervene between the two coal seams. this same displacement has also been traced downwards more than feet below the metal coal, but it grows continually less and less until it becomes imperceptible. no part of the process above described is more deserving of our notice than the slowness with which the change in the arrangement of the beds is brought about. days, months, or even years, will sometimes elapse between the first bending of the pavement and the time of its reaching the roof. where the movement has been most rapid, the curvature of the beds is most regular, and the reunion of the fractured ends most complete; whereas the signs of displacement or violence are greatest in those creeps which have required months or years for their entire accomplishment. hence we may conclude that similar changes may have been wrought on a larger scale in the earth's crust by partial and gradual subsidences, especially where the ground has been undermined throughout long periods of time; and we must be on our guard against inferring sudden violence, simply because the distortion of the beds is excessive. between the layers of shale, accompanying coal, we sometimes see the leaves of fossil ferns spread out as regularly as dried plants between sheets of paper in the herbarium of a botanist. these fern-leaves, or fronds, must have rested horizontally on soft mud, when first deposited. if, therefore, they and the layers of shale are now inclined, or standing on end, it is obviously the effect of subsequent derangement. the proof becomes, if possible, still more striking when these strata, including vegetable remains, are curved again and again, and even folded into the form of the letter z, so that the same continuous layer of coal is cut through several times in the same perpendicular shaft. thus, in the coal-field near mons, in belgium, these zigzag bendings are repeated four or five times, in the manner represented in fig. ., the black lines representing seams of coal.[ -a] [illustration: fig. . zigzag flexures of coal near mons.] _dip and strike._--in the above remarks, several technical terms have been used, such as _dip_, the _unconformable position_ of strata, and the _anticlinal_ and _synclinal_ lines, which, as well as the _strike_ of the beds, i shall now explain. if a stratum or bed of rock, instead of being quite level, be inclined to one side, it is said to _dip_; the point of the compass to which it is inclined is called the _point of dip_, and the degree of deviation from a level or horizontal line is called _the amount of dip_, or _the angle of dip_. thus, in the annexed diagram (fig. .), a series of strata are inclined, and they dip to the north at an angle of forty-five degrees. the _strike_, or _line of bearing_, is the prolongation or extension of the strata in a direction _at right angles_ to the dip; and hence it is sometimes called the _direction_ of the strata. thus, in the above instance of strata dipping to the north, their strike must necessarily be east and west. we have borrowed the word from the german geologists, _streichen_ signifying to extend, to have a certain direction. dip and strike may be aptly illustrated by a row of houses running east and west, the long ridge of the roof representing the strike of the stratum of slates, which dip on one side to the north, and on the other to the south. [illustration: fig. . diagram.] a stratum which is horizontal, or quite level in all directions, has neither dip nor strike. it is always important for the geologist, who is endeavouring to comprehend the structure of a country, to learn how the beds dip in every part of the district; but it requires some practice to avoid being occasionally deceived, both as to the point of dip and the amount of it. [illustration: fig. . apparent horizontality of inclined strata.] if the upper surface of a hard stony stratum be uncovered, whether artificially in a quarry, or by the waves at the foot of a cliff, it is easy to determine towards what point of the compass the slope is steepest, or in what direction water would flow, if poured upon it. this is the true dip. but the edges of highly inclined strata may give rise to perfectly horizontal lines in the face of a vertical cliff, if the observer see the strata in the line of their strike, the dip being inwards from the face of the cliff. if, however, we come to a break in the cliff, which exhibits a section exactly at right angles to the line of the strike, we are then able to ascertain the true dip. in the annexed drawing (fig. .), we may suppose a headland, one side of which faces to the north, where the beds would appear perfectly horizontal to a person in the boat; while in the other side facing the west, the true dip would be seen by the person on shore to be at an angle of °. if, therefore, our observations are confined to a vertical precipice facing in one direction, we must endeavour to find a ledge or portion of the plane of one of the beds projecting beyond the others, in order to ascertain the true dip. [illustration: fig. . explanatory sketch.] it is rarely important to determine the angle of inclination with such minuteness as to require the aid of the instrument called a clinometer. we may measure the angle within a few degrees by standing exactly opposite to a cliff where the true dip is exhibited, holding the hands immediately before the eyes, and placing the fingers of one in a perpendicular, and of the other in a horizontal position, as in fig. . it is thus easy to discover whether the lines of the inclined beds bisect the angle of °, formed by the meeting of the hands, so as to give an angle of °, or whether it would divide the space into two equal or unequal portions. the upper dotted line may express a stratum dipping to the north; but should the beds dip precisely to the opposite point of the compass as in the lower dotted line, it will be seen that the amount of inclination may still be measured by the hands with equal facility. [illustration: fig. . section illustrating the structure of the swiss jura.] [illustration: fig. . ground plan of the denuded ridge, fig. .] [illustration: fig. . transverse section.] it has been already seen, in describing the curved strata on the east coast of scotland, in forfarshire and berwickshire, that a series of concave and convex bendings are occasionally repeated several times. these usually form part of a series of parallel waves of strata, which are prolonged in the same direction throughout a considerable extent of country. thus, for example, in the swiss jura, that lofty chain of mountains has been proved to consist of many parallel ridges, with intervening longitudinal valleys, as in fig. ., the ridges being formed by curved fossiliferous strata, of which the nature and dip are occasionally displayed in deep transverse gorges, called "cluses," caused by fractures at right angles to the direction of the chain.[ -a] now let us suppose these ridges and parallel valleys to run north and south, we should then say that the _strike_ of the beds is north and south, and the _dip_ east and west. lines drawn along the summits of the ridges, a, b, would be anticlinal lines, and one following the bottom of the adjoining valleys a synclinal line. it will be observed that some of these ridges, a, b, are unbroken on the summit, whereas one of them, c, has been fractured along the line of strike, and a portion of it carried away by denudation, so that the ridges of the beds in the formations _a_, _b_, _c_, come out to the day, or, as the miners say, _crop out_, on the sides of a valley. the ground plan of such a denuded ridge as c, as given in a geological map, may be expressed by the diagram fig. ., and the cross section of the same by fig. . the line d e, fig. ., is the anticlinal line, on each side of which the dip is in opposite directions, as expressed by the arrows. the emergence of strata at the surface is called by miners their _outcrop_ or _basset_. if, instead of being folded into parallel ridges, the beds form a boss or dome-shaped protuberance, and if we suppose the summit of the dome carried off, the ground plan would exhibit the edges of the strata forming a succession of circles, or ellipses, round a common centre. these circles are the lines of strike, and the dip being always at right angles is inclined in the course of the circuit to every point of the compass, constituting what is termed a qua-quaversal dip--that is, turning each way. there are endless variations in the figures described by the basset-edges of the strata, according to the different inclination of the beds, and the mode in which they happen to have been denuded. one of the simplest rules with which every geologist should be acquainted, relates to the v-like form of the beds as they crop out in an ordinary valley. first, if the strata be horizontal, the v-like form will be also on a level, and the newest strata will appear at the greatest heights. secondly, if the beds be inclined and intersected by a valley sloping in the same direction, and the dip of the beds be less steep than the slope of the valley, then the v's, as they are often termed by miners, will point upwards (see fig. .), those formed by the newer beds appearing in a superior position, and extending highest up the valley, as a is seen above b. [illustration: fig. . slope of valley °, dip of strata °.] thirdly, if the dip of the beds be steeper than the slope of the valley, then the v's will point downwards (see fig. .), and those formed of the older beds will now appear uppermost, as b appears above a. [illustration: fig. . slope of valley °, dip of strata °.] fourthly, in every case where the strata dip in a contrary direction to the slope of the valley, whatever be the angle of inclination, the newer beds will appear the highest, as in the first and second cases. this is shown by the drawing (fig. .), which exhibits strata rising at an angle of °, and crossed by a valley, which declines in an opposite direction at °.[ -a] [illustration: fig. . slope of valley °, dip of strata °, in opposite directions.] these rules may often be of great practical utility; for the different degrees of dip occurring in the two cases represented in figures and . may occasionally be encountered in following the same line of flexure at points a few miles distant from each other. a miner unacquainted with the rule, who had first explored the valley (fig. .), may have sunk a vertical shaft below the coal seam a, until he reached the inferior bed b. he might then pass to the valley fig. ., and discovering there also the outcrop of two coal seams, might begin his workings in the uppermost in the expectation of coming down to the other bed a, which would be observed cropping out lower down the valley. but a glance at the section will demonstrate the futility of such hopes. in the majority of cases, an anticlinal axis forms a ridge, and a synclinal axis a valley, as in a, b, fig. . p. .; but there are exceptions to this rule, the beds sometimes sloping inwards from either side of a mountain, as in fig. . [illustration: fig. . cross section.] on following one of the anticlinal ridges of the jura, before mentioned, a, b, c, fig. ., we often discover longitudinal cracks and sometimes large fissures along the line where the flexure was greatest. some of these, as above stated, have been enlarged by denudation into valleys of considerable width, as at c, fig. ., which follow the line of strike, and which we may suppose to have been hollowed out at the time when these rocks were still beneath the level of the sea, or perhaps at the period of their gradual emergence from beneath the waters. the existence of such cracks at the point of the sharpest bending of solid strata of limestone is precisely what we should have expected; but the occasional want of all similar signs of fracture, even where the strain has been greatest, as at _a_, fig. ., is not always easy to explain. we must imagine that many strata of limestone, chert, and other rocks which are now brittle, were pliant when bent into their present position. they may have owed their flexibility in part to the fluid matter which they contained in their minute pores, as before described (p. .), and in part to the permeation of sea-water while they were yet submerged. [illustration: fig. . strata of chert, grit, and marl, near st. jean de luz.] at the western extremity of the pyrenees, great curvatures of the strata are seen in the sea cliffs, where the rocks consist of marl, grit, and chert. at certain points, as at _a_, fig. ., some of the bendings of the flinty chert are so sharp, that specimens might be broken off, well fitted to serve as ridge-tiles on the roof of a house. although this chert could not have been brittle as now, when first folded into this shape, it presents, nevertheless, here and there at the points of greatest flexure small cracks, which show that it was solid, and not wholly incapable of breaking at the period of its displacement. the numerous rents alluded to are not empty, but filled with calcedony and quartz. [illustration: fig. . cross section. _g._ gypsum. _m._ marl.] between san caterina and castrogiovanni, in sicily, bent and undulating gypseous marls occur, with here and there thin beds of solid gypsum interstratified. sometimes these solid layers have been broken into detached fragments, still preserving their sharp edges (_g g_, fig. .), while the continuity of the more pliable and ductile marls, _m m_, has not been interrupted. [illustration: fig. . cross section.] i shall conclude my remarks on bent strata by stating, that, in mountainous regions like the alps, it is often difficult for an experienced geologist to determine correctly the relative age of beds by superposition, so often have the strata been folded back upon themselves, the upper parts of the curve having been removed by denudation. thus, if we met with the strata seen in the section fig. ., we should naturally suppose that there were twelve distinct beds, or sets of beds, no. . being the newest, and no. . the oldest of the series. but this section may, perhaps, exhibit merely six beds, which have been folded in the manner seen in fig. ., so that each of them is twice repeated, the position of one half being reversed, and part of no. ., originally the uppermost, having now become the lowest of the series. these phenomena are often observable on a magnificent scale in certain regions in switzerland in precipices from to feet in perpendicular height. in the iselten alp, in the valley of the lutschine, between unterseen and grindelwald, curves of calcareous shale are seen from to feet in height, in which the beds sometimes plunge down vertically for a depth of feet and more, before they bend round again. there are many flexures not inferior in dimensions in the pyrenees, as those near gavarnie, at the base of mont perdu. [illustration: fig. . cross section.] [illustration: fig. . curved strata of the iselten alp.] [illustration: fig. . unconformable junction of old red sandstone and silurian schist at the siccar point, near st. abb's head, berwickshire. see also frontispiece.] _unconformable stratification._--strata are said to be unconformable, when one series is so placed over another, that the planes of the superior repose on the edges of the inferior (see fig. .). in this case it is evident that a period had elapsed between the production of the two sets of strata, and that, during this interval, the older series had been tilted and disturbed. afterwards the upper series was thrown down in horizontal strata upon it. if these superior beds, as _d_, _d_, fig. ., are also inclined, it is plain that the lower strata, _a_, _a_, have been twice displaced; first, before the deposition of the newer beds, _d_, _d_, and a second time when these same strata were thrown out of the horizontal position. playfair has remarked[ -a] that this kind of junction which we now call unconformable had been described before the time of hutton, but that he was the first geologist who appreciated its importance, as illustrating the high antiquity and great revolutions of the globe. he had observed that where such contacts occur, the lowest beds of the newer series very generally consist of a breccia or conglomerate consisting of angular and rounded fragments, derived from the breaking up of the more ancient rocks. on one occasion the scotch geologist took his two distinguished pupils, playfair and sir james hall, to the cliffs on the east coast of scotland, near the village of eyemouth, not far from st. abb's head, where the schists of the lammermuir range are undermined and dissected by the sea. here the curved and vertical strata, now known to be of silurian age, and which often exhibit a ripple-marked surface[ -b], are well exposed at the headland called the siccar point, penetrating with their edges into the incumbent beds of slightly inclined sandstone, in which large pieces of the schist, some round and others angular, are united by an arenaceous cement. "what clearer evidence," exclaims playfair, "could we have had of the different formation of these rocks, and of the long interval which separated their formation, had we actually seen them emerging from the bosom of the deep? we felt ourselves necessarily carried back to the time when the schistus on which we stood was yet at the bottom of the sea, and when the sandstone before us was only beginning to be deposited in the shape of sand or mud, from the waters of a superincumbent ocean. an epoch still more remote presented itself, when even the most ancient of these rocks, instead of standing upright in vertical beds, lay in horizontal planes at the bottom of the sea, and was not yet disturbed by that immeasurable force which has burst asunder the solid pavement of the globe. revolutions still more remote appeared in the distance of this extraordinary perspective. the mind seemed to grow giddy by looking so far into the abyss of time; and while we listened with earnestness and admiration to the philosopher who was now unfolding to us the order and series of these wonderful events, we became sensible how much farther reason may sometimes go than imagination can venture to follow."[ -c] in the frontispiece of this volume the reader will see a view of this classical spot, reduced from a large picture, faithfully sketched and coloured from nature by the youngest son of the late sir james hall. it was impossible, however, to do justice to the original sketch, in an engraving, as the contrast of the red sandstone and the light fawn-coloured vertical schists could not be expressed. from the point of view here selected, the underlying beds of the perpendicular schist, _a_, are visible at _b_ through a small opening in the fractured beds of the covering of red sandstone, _d d_, while on the vertical face of the old schist at _a' a"_ a conspicuous ripple-mark is displayed. [illustration: fig. . junction of unconformable strata near mons, in belgium.] it often happens that in the interval between the deposition of two sets of unconformable strata, the inferior rock has not only been denuded, but drilled by perforating shells. thus, for example, at autreppe and gusigny, near mons, beds of an ancient (paleozoic) limestone, highly inclined, and often bent, are covered with horizontal strata of greenish and whitish marls of the cretaceous formation. the lowest and therefore the oldest bed of the horizontal series is usually the sand and conglomerate, _a_, in which are rounded fragments of stone, from an inch to two feet in diameter. these fragments have often adhering shells attached to them, and have been bored by perforating mollusca. the solid surface of the inferior limestone has also been bored, so as to exhibit cylindrical and pear-shaped cavities, as at _c_, the work of saxicavous mollusca; and many rents, as at _b_, which descend several feet or yards into the limestone, have been filled with sand and shells, similar to those in the stratum _a_. _fractures of the strata and faults._--numerous rents may often be seen in rocks which appear to have been simply broken, the separated parts remaining in the same places; but we often find a fissure, several inches or yards wide, intervening between the disunited portions. these fissures are usually filled with fine earth and sand, or with angular fragments of stone, evidently derived from the fracture of the contiguous rocks. the face of each wall of the fissure is often beautifully polished, as if glazed, and not unfrequently striated or scored with parallel furrows and ridges, such as would be produced by the continued rubbing together of surfaces of unequal hardness. these polished surfaces are called by miners "slickensides." it is supposed that the lines of the striæ indicate the direction in which the rocks were moved. during one of the minor earthquakes in chili, which happened about the year , and was described to me by an eye-witness, the brick walls of a building were rent vertically in several places, and made to vibrate for several minutes during each shock, after which they remained uninjured, and without any opening, although the line of each crack was still visible. when all movement had ceased, there were seen on the floor of the house, at the bottom of each rent, small heaps of fine brickdust, evidently produced by trituration. [illustration: fig. . faults. a b perpendicular, c d oblique to the horizon.] it is not uncommon to find the mass of rock, on one side of a fissure, thrown up above or down below the mass with which it was once in contact on the other side. this mode of displacement is called a shift, slip, or fault. "the miner," says playfair, describing a fault, "is often perplexed, in his subterraneous journey, by a derangement in the strata, which changes at once all those lines and bearings which had hitherto directed his course. when his mine reaches a certain plane, which is sometimes perpendicular, as in a b, fig. ., sometimes oblique to the horizon (as in c d, ibid.), he finds the beds of rock broken asunder, those on the one side of the plane having changed their place, by sliding in a particular direction along the face of the others. in this motion they have sometimes preserved their parallelism, as in fig. ., so that the strata on each side of the faults a b, c d, continue parallel to one another; in other cases, the strata on each side are inclined, as in _a_, _b_, _c_, _d_ (fig. .), though their identity is still to be recognized by their possessing the same thickness, and the same internal characters."[ -a] [illustration: fig. . e f, fault or fissure filled with rubbish, on each side of which the shifted strata are not parallel.] in coalbrook dale, says mr. prestwich[ -b], deposits of sandstone, shale, and coal, several thousand feet thick, and occupying an area of many miles, have been shivered into fragments, and the broken remnants have been placed in very discordant positions, often at levels differing several hundred feet from each other. the sides of the faults, when perpendicular, are commonly separated several yards, but are sometimes as much as yards asunder, the interval being filled with broken _débris_ of the strata. in following the course of the same fault it is sometimes found to produce in different places very unequal changes of level, the amount of shift being in one place , and in another feet, which arises, in some cases, from the union of two or more faults. in other words, the disjointed strata have in certain districts been subjected to renewed movements, which they have not suffered elsewhere. we may occasionally see exact counterparts of these slips, on a small scale, in pits of fine loose sand and gravel, many of which have doubtless been caused by the drying and shrinking of argillaceous and other beds, slight subsidences having taken place from failure of support. sometimes, however, even these small slips may have been produced during earthquakes; for land has been moved, and its level, relatively to the sea, considerably altered, within the period when much of the alluvial sand and gravel now covering the surface of continents was deposited. i have already stated that a geologist must be on his guard, in a region of disturbed strata, against inferring repeated alternations of rocks, when, in fact, the same strata, once continuous, have been bent round so as to recur in the same section, and with the same dip. a similar mistake has often been occasioned by a series of faults. [illustration: fig. . apparent alternations of strata caused by vertical faults.] if, for example, the dark line a h (fig. .) represent the surface of a country on which the strata _a b c_ frequently crop out, an observer, who is proceeding from h to a, might at first imagine that at every step he was approaching new strata, whereas the repetition of the same beds has been caused by vertical faults, or downthrows. thus, suppose the original mass, a, b, c, d, to have been a set of uniformly inclined strata, and that the different masses under e f, f g, and g d, sank down successively, so as to leave vacant the spaces marked in the diagram by dotted lines, and to occupy those marked by the continuous lines, then let denudation take place along the line a h, so that the protruding masses indicated by the fainter lines are swept away,--a miner, who has not discovered the faults, finding the mass _a_, which we will suppose to be a bed of coal four times repeated, might hope to find four beds, workable to an indefinite depth, but first on arriving at the fault g he is stopped suddenly in his workings, upon reaching the strata of sandstone _c_, or on arriving at the line of fault f he comes partly upon the shale _b_, and partly on the sandstone _c_, and on reaching e he is again stopped by a wall composed of the rock _d_. [illustration: fig. . cross section.] the very different levels at which the separated parts of the same strata are found on the different sides of the fissure, in some faults, is truly astonishing. one of the most celebrated in england is that called the "ninety-fathom dike," in the coal-field of newcastle. this name has been given to it, because the same beds are ninety fathoms lower on the northern than they are on the southern side. the fissure has been filled by a body of sand, which is now in the state of sandstone, and is called the dike, which is sometimes very narrow, but in other places more than twenty yards wide.[ -a] the walls of the fissure are scored by grooves, such as would have been produced if the broken ends of the rock had been rubbed along the plane of the fault.[ -b] in the tynedale and craven faults, in the north of england, the vertical displacement is still greater, and has extended in a horizontal direction for a distance of thirty miles or more. some geologists consider it necessary to imagine that the upward or downward movement in these cases was accomplished at a single stroke, and not by a series of sudden but interrupted movements. this idea appears to have been derived from a notion that the grooved walls have merely been rubbed in one direction. but this is so far from being a constant phenomenon in faults, that it has often been objected to the received theory respecting those polished surfaces called "slickensides" (see above, p. .), that the striæ are not always parallel, but often curved and irregular. it has, moreover, been remarked, that not only the walls of the fissure or fault, but its earthy contents, sometimes present the same polished and striated faces. now these facts seem to indicate partial changes in the direction of the movement, and some slidings subsequent to the first filling up of the fissure. suppose the mass of rock a, b, c, to overlie an extensive chasm _d e_, formed at the depth of several miles, whether by the gradual contraction in bulk of a melted mass passing into a solid or crystalline state, or the shrinking of argillaceous strata, baked by a moderate heat, or by the subtraction of matter by volcanic action, or any other cause. now, if this region be convulsed by earthquakes, the fissures _f g_, and others at right angles to them, may sever the mass b from a and from c, so that it may move freely, and begin to sink into the chasm. a fracture may be conceived so clean and perfect as to allow it to subside at once to the bottom of the subterranean cavity; but it is far more probable that the sinking will be effected at successive periods during different earthquakes, the mass always continuing to slide in the same direction along the planes of the fissures _f g_, and the edges of the falling mass being continually more broken and triturated at each convulsion. if, as is not improbable, the circumstances which have caused the failure of support continue in operation, it may happen that when the mass b has filled the cavity first formed, its foundations will again give way under it, so that it will fall again in the same direction. but, if the direction should change, the fact could not be discovered by observing the slickensides, because the last scoring would efface the lines of previous friction. in the present state of our ignorance of the causes of subsidence, an hypothesis which can explain the great amount of displacement in some faults, on sound mechanical principles, by a succession of movements, is far preferable to any theory which assumes each fault to have been accomplished by a single upcast or downthrow of several thousand feet. for we know that there are operations now in progress, at great depths in the interior of the earth, by which both large and small tracts of ground are made to rise above and sink below their former level, some slowly and insensibly, others suddenly and by starts, a few feet or yards at a time; whereas there are no grounds for believing that, during the last years at least, any regions have been either upheaved or depressed, at a single stroke, to the amount of several hundred, much less several thousand feet. when some of the ancient marine formations are described in the sequel, it will appear that their structure and organic contents point to the conclusion, that the floor of the ocean was slowly sinking at the time of their origin. the downward movement was very gradual, and in wales and the contiguous parts of england a maximum thickness of , feet (more than six miles) of carboniferous, devonian, and silurian rock was formed, whilst the bed of the sea was all the time continuously and tranquilly subsiding.[ -a] whatever may have been the changes which the solid foundation underwent, whether accompanied by the melting, consolidation, crystallization, or desiccation of subjacent mineral matter, it is clear from the fact of the sea having remained shallow all the while that the bottom never sank down suddenly to the depth of many hundred feet at once. it is by assuming such reiterated variations of level, each separately of small vertical amount, but multiplied by time till they acquire importance in the aggregate, that we are able to explain the phenomena of denudation, which will be treated of in the next chapter. by such movements every portion of the surface of the land becomes in its turn a line of coast, and is exposed to the action of the waves and tides. a country which is undergoing such movement is never allowed to settle into a state of equilibrium, therefore the force of rivers and torrents to remove or excavate soil and rocky masses is sustained in undiminished energy. footnotes: [ -a] in the first three editions of my principles of geology, i expressed many doubts as to the validity of the alleged proofs of a gradual rise of land in sweden; but after visiting that country, in , i retracted these objections, and published a detailed statement of the observations which led me to alter my opinion in the phil. trans. , part i. see also the principles, th and subsequent editions. [ -b] see his journal of a naturalist in voyage of the beagle, and his work on coral reefs. [ -c] see chapters xxviii. to xxxi. inclusive. [ -a] edin. trans. vol. vii. pl. . [ -a] proceedings of geol. soc. vol. iii. p. . [ -a] see plan by m. chevalier, burat's d'aubuisson, tom. ii. p. . [ -a] see m. thurmann's work, "essai sur les soulèvemens jurassiques du porrentruy, paris, ," with whom i examined part of these mountains in . [ -a] i am indebted to the kindness of t. sopwith, esq., for three models which i have copied in the above diagrams; but the beginner may find it by no means easy to understand such copies, although, if he were to examine and handle the originals, turning them about in different ways, he would at once comprehend their meaning as well as the import of others far more complicated, which the same engineer has constructed to illustrate _faults_. [ -a] biographical account of dr. hutton. [ -b] see above, p. . and section. [ -c] playfair, ibid.; see his works, edin. , vol. iv. p. . [ -a] playfair, illust. of hutt. theory, § . [ -b] geol. trans. second series, vol. v. p. . [ -a] conybeare and phillips, outlines, &c. p. . [ -b] phillips, geology, lardner's cyclop. p. . [ -a] see the results of the "geological survey of great britain;" memoirs, vols. i. and ii., by sir h. de la beche, mr. a. c. ramsay, and mr. john phillips. chapter vi. denudation. denudation defined--its amount equal to the entire mass of stratified deposits in the earth's crust--horizontal sandstone denuded in ross-shire--levelled surface of countries in which great faults occur--coalbrook dale--denuding power of the ocean during the emergence of land--origin of valleys--obliteration of sea-cliffs--inland sea-cliffs and terraces in the morea and sicily--limestone pillars at st. mihiel, in france--in canada--in the bermudas. denudation, which has been occasionally spoken of in the preceding chapters, is the removal of solid matter by water in motion, whether of rivers or of the waves and currents of the sea, and the consequent laying bare of some inferior rock. geologists have perhaps been seldom in the habit of reflecting that this operation has exerted an influence on the structure of the earth's crust as universal and important as sedimentary deposition itself; for denudation is the inseparable accompaniment of the production of all new strata of mechanical origin. the formation of every new deposit by the transport of sediment and pebbles necessarily implies that there has been, somewhere else, a grinding down of rock into rounded fragments, sand, or mud, equal in quantity to the new strata. all deposition, therefore, except in the case of a shower of volcanic ashes, is the sign of superficial waste going on contemporaneously, and to an equal amount elsewhere. the gain at one point is no more than sufficient to balance the loss at some other. here a lake has grown shallower, there a ravine has been deepened. the bed of the sea has in one region been raised by the accumulation of new matter, in another its depth has been augmented by the abstraction of an equal quantity. when we see a stone building, we know that somewhere, far or near, a quarry has been opened. the courses of stone in the building may be compared to successive strata, the quarry to a ravine or valley which has suffered denudation. as the strata, like the courses of hewn stone, have been laid one upon another gradually, so the excavation both of the valley and quarry have been gradual. to pursue the comparison still farther, the superficial heaps of mud, sand, and gravel, usually called alluvium, may be likened to the rubbish of a quarry which has been rejected as useless by the workmen, or has fallen upon the road between the quarry and the building, so as to lie scattered at random over the ground. if, then, the entire mass of stratified deposits in the earth's crust is at once the monument and measure of the denudation which has taken place, on how stupendous a scale ought we to find the signs of this removal of transported materials in past ages! accordingly, there are different classes of phenomena, which attest in a most striking manner the vast spaces left vacant by the erosive power of water. i may allude, first, to those valleys on both sides of which the same strata are seen following each other in the same order, and having the same mineral composition and fossil contents. we may observe, for example, several formations, as nos. , , , , in the accompanying diagram (fig. .); no. . conglomerate, no. . clay, no. . grit, and no. . limestone, each repeated in a series of hills separated by valleys varying in depth. when we examine the subordinate parts of these four formations, we find, in like manner, distinct beds in each, corresponding, on the opposite sides of the valleys, both in composition and order of position. no one can doubt that the strata were originally continuous, and that some cause has swept away the portions which once connected the whole series. a torrent on the side of a mountain produces similar interruptions; and when we make artificial cuts in lowering roads, we expose, in like manner, corresponding beds on either side. but in nature, these appearances occur in mountains several thousand feet high, and separated by intervals of many miles or leagues in extent, of which a grand exemplification is described by dr. macculloch, on the north-western coast of ross-shire, in scotland.[ -a] the fundamental rock of that country is gneiss, in disturbed strata, on which beds of nearly horizontal red sandstone rest unconformably. the latter are often very thin, forming mere flags, with their surfaces, distinctly ripple-marked. they end abruptly on the declivities of many insulated mountains, which rise up at once to the height of about feet above the gneiss of the surrounding plain or table land, and to an average elevation of about feet above the sea, which all their summits generally attain. the base of gneiss varies in height, so that the lower portions of the sandstone occupy different levels, and the thickness of the mass is various, sometimes exceeding feet. it is impossible to compare these scattered and detached portions without imagining that the whole country has once been covered with a great body of sandstone, and that masses from to more than feet in thickness have been removed. [illustration: fig. . valleys of denudation. _a._ alluvium.] [illustration: fig. . denudation of red sandstone on north-west coast of ross-shire. (macculloch.)] in the "survey of great britain" (vol. i.), professor ramsay has shown that the missing beds, removed from the summit of the mendips, must have been nearly a mile in thickness; and he has pointed out considerable areas in south wales and some of the adjacent counties of england, where a series of palæozoic strata, not less than , feet in thickness, have been stripped off. all these materials have of course been transported to new regions, and have entered into the composition of more modern formations. on the other hand, it is shown by observations in the same "survey," that the palæozoic strata are from , to , feet thick. it is clear that such rocks, formed of mud and sand, now for the most part consolidated, are the monuments of denuding operations, which took place on a grand scale at a very remote period in the earth's history. for, whatever has been given to one area must always have been borrowed from another; a truth which, obvious as it may seem when thus stated, must be repeatedly impressed on the student's mind, because in many geological speculations it is taken for granted that the external crust of the earth has been always growing thicker, in consequence of the accumulation, period after period, of sedimentary matter, as if the new strata were not always produced at the expense of pre-existing rocks, stratified or unstratified. by duly reflecting on the fact, that all deposits of mechanical origin imply the transportation from some other region, whether contiguous or remote, of an equal amount of solid matter, we perceive that the stony exterior of the planet must always have grown thinner in one place whenever, by accessions of new strata, it was acquiring density in another. no doubt the vacant space left by the missing rocks, after extensive denudation, is less imposing to the imagination than a vast thickness of conglomerate or sandstone, or the bodily presence as it were of a mountain-chain, with all its inclined and curved strata. but the denuded tracts speak a clear and emphatic language to our reason, and, like repeated layers of fossil nummulites, corals or shells, or like numerous seams of coal, each based on its under clay full of the roots of trees, still remaining in their natural position, demand an indefinite lapse of time for their elaboration. no one will maintain that the fossils entombed in these rocks did not belong to many successive generations of plants and animals. in like manner, each sedimentary deposit attests a slow and gradual action, and the strata not only serve as a measure of the amount of denudation simultaneously effected elsewhere, but are also a correct indication of the rate at which the denuding operation was carried on. perhaps the most convincing evidence of denudation on a magnificent scale is derived from the levelled surfaces of districts where large faults occur. i have shown, in fig. . p. ., and in fig. ., how angular and protruding masses of rock might naturally have been looked for on the surface immediately above great faults, although in fact they rarely exist. this phenomenon may be well studied in those districts where coal has been extensively worked, for there the former relation of the beds which have shifted their position may be determined with great accuracy. thus in the coal field of ashby de la zouch, in leicestershire (see fig. .), a fault occurs, on one side of which the coal beds _a b c d_ rise to the height of feet above the corresponding beds on the other side. but the uplifted strata do not stand up feet above the general surface; on the contrary, the outline of the country, as expressed by the line _z z_, is uniform and unbroken, and the mass indicated by the dotted outline must have been washed away.[ -a] there are proofs of this kind in some level countries, where dense masses of strata have been cleared away from areas several hundred square miles in extent. [illustration: fig. . faults and denuded coal strata, ashby de la zouch. (mammat.)] in the newcastle coal district it is ascertained that faults occur in which the upward or downward movement could not have been less than fathoms, which, had they affected equally the configuration of the surface to that amount, would produce mountains with precipitous escarpments nearly feet high, or chasms of the like depth; yet is the actual level of the country absolutely uniform--affording no trace whatever of subterranean movements.[ -b] the ground from which these materials have been removed is usually overspread with heaps of sand and gravel, formed out of the ruins of the very rocks which have disappeared. thus, in the districts above referred to, they consist of rounded and angular fragments of hard sandstone, limestone, and ironstone, with a small quantity of the more destructible shale, and even rounded pieces of coal. allusion has been already made to the shattered state and discordant position of the carboniferous strata in coalbrook dale (p. .). the collier cannot proceed three or four yards without meeting with small slips, and from time to time he encounters faults of considerable magnitude, which have thrown the rocks up or down several hundred feet. yet the superficial inequalities to which these dislocated masses originally gave rise are no longer discernible, and the comparative flatness of the existing surface can only be explained, as mr. prestwich has observed, by supposing the fractured portions to have been removed by water. it is also clear that strata of red sandstone, more than feet thick, which once covered the coal, in the same region, have been carried away from large areas. that water has, in this case, been the denuding agent, we may infer from the fact that the rocks have yielded according to their different degrees of hardness; the hard trap of the wrekin, for example, and other hills, having resisted more than the softer shale and sandstone, so as now to stand out in bold relief.[ -a] _origin of valleys._--many of the earlier geologists, and dr. hutton among them, taught that "rivers have in general hollowed out their valleys." this is true only of rivulets and torrents which are the feeders of the larger streams, and which, descending over rapid slopes, are most subject to temporary increase and diminution in the volume of their waters. the quantity of mud, sand, and pebbles constituting many a modern delta proves indisputably that no small part of the inequalities now existing on the earth's surface are due to fluviatile action; but the principal valleys in almost every great hydrographical basin in the world, are of a shape and magnitude which imply that they have been due to other causes besides the mere excavating power of rivers. some geologists have imagined that a deluge, or succession of deluges, may have been the chief denuding agency, and they have speculated on a series of enormous waves raised by the instantaneous upthrow of continents or mountain chains out of the sea. but even were we disposed to grant such sudden upheavals of the floor of the ocean, and to assume that great waves would be the consequence of each convulsion, it is not easy to explain the observed phenomena by the aid of so gratuitous an hypothesis. on the other hand, a machinery of a totally different kind seems capable of giving rise to effects of the required magnitude. it has now been ascertained that the rising and sinking of extensive portions of the earth's crust, whether insensibly or by a repetition of sudden shocks, is part of the actual course of nature, and we may easily comprehend how the land may have been exposed during these movements to abrasion by the waves of the sea. in the same manner as a mountain mass may, in the course of ages, be formed by sedimentary deposition, layer after layer, so masses equally voluminous may in time waste away by inches; as, for example, if beds of incoherent materials are raised slowly in an open sea where a strong current prevails. it is well known that some of these oceanic currents have a breadth of miles, and that they sometimes run for a thousand miles or more in one direction, retaining a considerable velocity even at the depth of several hundred feet. under these circumstances, the flowing waters may have power to clear away each stratum of incoherent materials as it rises and approaches the surface, where the waves exert the greatest force; and in this manner a voluminous deposit may be entirely swept away, so that, in the absence of faults, no evidence may remain of the denuding operation. it may indeed be affirmed that the signs of waste will usually be least obvious where the destruction has been most complete; for the annihilation may have proceeded so far, that no ruins are left of the dilapidated rocks. although denudation has had a levelling influence on some countries of shattered and disturbed strata (see fig. . p. . and fig. . p. .), it has more commonly been the cause of superficial inequalities, especially in regions of horizontal stratification. the general outline of these regions is that of flat and level platforms, interrupted by valleys often of considerable depth, and ramifying in various directions. these hollows may once have formed bays and channels between islands, and the steepest slope on the sides of each valley may have been a sea-cliff, which was undermined for ages, as the land emerged gradually from the deep. we may suppose the position and course of each valley to have been originally determined by differences in the hardness of the rocks, and by rents and joints which usually occur even in horizontal strata. in mountain chains, such as the jura before described (see fig. . p. .), we perceive at once that the principal valleys have not been due to aqueous excavation, but to those mechanical movements which have bent the rocks into their present form. yet even in the jura there are many valleys, such as c (fig. .), which have been hollowed out by water; and it may be stated that in every part of the globe the unevenness of the surface of the land has been due to the combined influence of subterranean movements and denudation. i may now recapitulate a few of the conclusions to which we have arrived: first, all the mechanical strata have been accumulated gradually, and the concomitant denudation has been no less gradual: secondly, the dry land consists in great part of strata formed originally at the bottom of the sea, and has been made to emerge and attain its present height by a force acting from beneath: thirdly, no combination of causes has yet been conceived so capable of producing extensive and gradual denudation, as the action of the waves and currents of the ocean upon land slowly rising out of the deep. now, if we adopt these conclusions, we shall naturally be led to look everywhere for marks of the former residence of the sea upon the land, especially near the coasts from which the last retreat of the waters took place, and it will be found that such signs are not wanting. i shall have occasion to speak of ancient sea-cliffs, now far inland, in the south-east of england, when treating in chapter xix. of the denudation of the chalk in surrey, kent, and sussex. lines of upraised sea-beaches of more modern date are traced, at various levels from to feet and upwards above the present sea-level, for great distances on the east and west coasts of scotland, as well as in devonshire, and other counties in england. these ancient beach-lines often form terraces of sand and gravel, including littoral shells, some broken, others entire, and corresponding with species now living on the adjoining coast. but it would be unreasonable to expect to meet everywhere with the signs of ancient shores, since no geologist can have failed to observe how soon all recent marks of the kind above alluded to are obscured or entirely effaced, wherever, in consequence of the altered state of the tides and currents, the sea has receded for a few centuries. we see the cliffs crumble down in a few years if composed of sand or clay, and soon reduced to a gentle slope. if there were shells on the beach they decompose, and their materials are washed away, after which the sand and shingle may resemble any other alluviums scattered over the interior. [illustration: fig. . section of inland cliff at abesse, near dax. _a._ sand of the landes. _b._ limestone. _c._ clay.] the features of an ancient shore may sometimes be concealed by the growth of trees and shrubs, or by a covering of blown sand, a good example of which occurs a few miles west from dax, near bordeaux, in the south of france. about twelve miles inland, a steep bank may be traced running in a direction nearly north-east and south-west, or parallel to the contiguous coast. this sudden fall of about feet conducts us from the higher platform of the landes to a lower plain which extends to the sea. the outline of the ground suggested to me, as it would do to every geologist, the opinion that the bank in question was once a sea-cliff, when the whole country stood at a lower level. but this is no longer matter of conjecture, for, in making excavations in for the foundation of a building at abesse, a quantity of loose sand, which formed the slope _d e_, was removed; and a perpendicular cliff, about feet in height, which had hitherto been protected from the agency of the elements, was exposed. at the bottom appeared the limestone _b_, containing tertiary shells and corals, immediately below it the clay _c_, and above it the usual tertiary sand _a_, of the department of the landes. at the base of the precipice were seen large partially rounded masses of rock, evidently detached from the stratum _b_. the face of the limestone was hollowed out and weathered into such forms as are seen in the calcareous cliffs of the adjoining coast, especially at biaritz, near bayonne. it is evident that, when the country was at a somewhat lower level, the sea advanced along the surface of the argillaceous stratum _c_, which, from its yielding nature, favoured the waste by allowing the more solid superincumbent stone _b_ to be readily undermined. afterwards, when the country had been elevated, part of the sand, _a_, fell down, or was drifted by the winds, so as to form the talus, _d e_, which masked the inland cliff until it was artificially laid open to view. when we are considering the various causes which, in the course of ages, may efface the characters of an ancient sea-coast, earthquakes must not be forgotten. during violent shocks, steep and overhanging cliffs are often thrown down and become a heap of ruins. sometimes unequal movements of upheaval or depression entirely destroy that horizontality of the base-line which constitutes the chief peculiarity of an ancient sea-cliff. it is, however, in countries where hard limestone rocks abound, that inland cliffs retain faithfully the characters which they acquired when they constituted the boundary of land and sea. thus, in the morea, no less than three, or even four, ranges of what were once sea-cliffs are well preserved. these have been described, by mm. boblaye and virlet, as rising one above the other at different distances from the actual shore, the summit of the highest and oldest occasionally exceeding feet in elevation. at the base of each there is usually a terrace, which is in some places a few yards, in others above yards wide, so that we are conducted from the high land of the interior to the sea by a succession of great steps. these inland cliffs are most perfect, and most exactly resemble those now washed by the waves of the mediterranean, where they are formed of calcareous rock, especially if the rock be a hard crystalline marble. the following are the points of correspondence observed between the ancient coast lines and the borders of the present sea:-- . a range of vertical precipices, with a terrace at their base. . a weathered state of the surface of the naked rock, such as the spray of the sea produces. . a line of littoral caverns at the foot of the cliffs. . a consolidated beach or breccia with occasional marine shells, found at the base of the cliffs, or in the caves. . lithodomous perforations. in regard to the first of these, it would be superfluous to dwell on the evidence afforded of the undermining power of waves and currents by perpendicular precipices. the littoral caves, also, will be familiar to those who have had opportunities of observing the manner in which the waves of the sea, when they beat against rocks, have power to scoop out caverns. as to the breccia, it is composed of pieces of limestone and rolled fragments of thick solid shell, such as _strombus_ and _spondylus_, all bound together by a crystalline calcareous cement. similar aggregations are now forming on the modern beaches of greece, and in caverns on the sea-side; and they are only distinguishable in character from those of more ancient date, by including many pieces of pottery. in regard to the _lithodomi_ above alluded to, these bivalve mollusks are well known to have the power of excavating holes in the hardest limestones, the size of the cavity keeping pace with the growth of the shell. when living they require to be always covered by salt water, but similar pear-shaped hollows, containing the dead shells of these creatures, are found at different heights on the face of the inland cliffs above mentioned. thus, for example, they have been observed near modon and navarino on cliffs in the interior feet high above the mediterranean. as to the weathered surface of the calcareous rocks, all limestones are known to suffer chemical decomposition when moistened by the spray of the salt water, and are corroded still more deeply at points lower down where they are just reached by the breakers. by this action the stone acquires a wrinkled and furrowed outline, and very near the sea it becomes rough and branching, as if covered with corals. such effects are traced not only on the present shore, but at the base of the ancient cliffs far in the interior. lastly, it remains only to speak of the terraces, which extend with a gentle slope from the base of almost all the inland cliffs, and are for the most part narrow where the rock is hard, but sometimes half a mile or more in breadth where it is soft. they are the effects of the encroachment of the ancient sea upon the shore at those levels at which the land remained for a long time stationary. the justness of this view is apparent on examining the shape of the modern shore wherever the sea is advancing upon the land, and removing annually small portions of undermined rock. by this agency a submarine platform is produced on which we may walk for some distance from the beach in shallow water, the increase of depth being very gradual, until we reach a point where the bottom plunges down suddenly. this platform is widened with more or less rapidity according to the hardness of the rocks, and when upraised it constitutes an inland terrace. but the four principal lines of cliff observed in the morea do not imply, as some have imagined, four great eras of sudden upheaval; they simply indicate the intermittence of the upheaving force. had the rise of the land been continuous and uninterrupted, there would have been no one prominent line of cliff; for every portion of the surface having been, in its turn, and for an equal period of time, a sea-shore, would have presented a nearly similar aspect. but if pauses occur in the process of upheaval, the waves and currents have time to sap, throw down, and clear away considerable masses of rock, and to shape out at certain levels lofty ranges of cliffs with broad terraces at their base. there are some levelled spaces, however, both ancient and modern, in the morea, which are not due to denudation, although resembling in outline the terraces above described. they may be called terraces of deposition, since they have resulted from the gain of land upon the sea where rivers and torrents have produced deltas. if the sedimentary matter has filled up a bay or gulf surrounded by steep mountains, a flat plain is formed skirting the inland precipices; and if these deposits are upraised, they form a feature in the landscape very similar to the areas of denudation before described. in the island of sicily i have examined many inland cliffs like those of the morea; as, for example, near palermo, where a precipice is seen consisting of limestone at the base of which are numerous caves. one of these called san ciro, about miles distant from palermo, is about feet high, wide, and above the sea. within it is found an ancient beach (_b_, fig. .), formed of pebbles of various rocks, many of which must have come from places far remote. broken pieces of coral and shell, especially of oysters and pectens, are seen intermingled with the pebbles. immediately above the level of this beach, _serpulæ_ are still found adhering to the face of the rock, and the limestone is perforated by _lithodomi_. within the grotto, also, at the same level, similar perforations occur; and so numerous are the holes, that the rock is compared by hoffmann to a target pierced by musket balls. but in order to expose to view these marks of boring-shells in the interior of the cave, it was necessary first to remove a mass of breccia, which consisted of numerous fragments of rock and an immense quantity of bones of the mammoth, hippopotamus, and other quadrupeds, imbedded in a dark brown calcareous marl. many of the bones were rolled as if partially subjected to the action of the waves. below this breccia, which is about feet thick, was found a bed of sand filled with sea-shells of recent species; and underneath the sand, again, is the secondary limestone of monte grifone. the state of the surface of the limestone in the cave above the level of the marine sand is very different from that below it. _above_, the rock is jagged and uneven, as is usual in the roofs and sides of limestone caverns; _below_, the surface is smooth and polished, as if by the attrition of the waves. [illustration: fig. . cross section. _a._ monte grifone. _b._ cave of san ciro.[ -a] _c._ plain of palermo, in which are newer pliocene strata of limestone and sand. _d._ bay of palermo.] the platform indicated at _c_, fig. ., is formed by a tertiary deposit containing marine shells almost all of living species, and it affords an illustration of the terrace of deposition, or the last of the two kinds before mentioned (p. .). there are also numerous instances in sicily of terraces of denudation. one of these occurs on the east coast to the north of syracuse, and the same is resumed to the south beyond the town of noto, where it may be traced forming a continuous and lofty precipice, _a b_, fig. ., facing towards the sea, and constituting the abrupt termination of a calcareous formation, which extends in horizontal strata far inland. this precipice varies in height from to feet, and between its base and the sea is an inferior platform, _c b_, consisting of similar white limestone. all the beds dip towards the sea, but are usually inclined at a very slight angle: they are seen to extend uninterruptedly from the base of the escarpment into the platform, showing distinctly that the lofty cliff was not produced by a fault or vertical shift of the beds, but by the removal of a considerable mass of rock. hence we may conclude that the sea, which is now undermining the cliffs of the sicilian coast, reached at some former period the base of the precipice _a b_, at which time the surface of the terrace _c b_ must have been covered by the mediterranean. there was a pause, therefore, in the upward movement, when the waves of the sea had time to carve out the platform _c b_; but there may have been many other stationary periods of minor duration. suppose, for example, that a series of escarpments _e_, _f_, _g_, _h_, once existed, and that the sea, during a long interval free from subterranean movements, advances along the line _c b_, all preceding cliffs must have been swept away one after the other, and reduced to the single precipice _a b_. [illustration: fig. . cross section.] [illustration: fig. . valley called gozzo degli martiri, below melilli, val di noto.] that such a series of smaller cliffs, as those represented at _e_, _f_, _g_, _h_, fig. ., did really once exist at intermediate heights in place of the single precipice _a b_, is rendered highly probable by the fact, that in certain bays and inland valleys opening towards the east coast of sicily, and not far from the section given in fig. ., the solid limestone is shaped out into a great succession of ledges, separated from each other by small vertical cliffs. these are sometimes so numerous, one above the other, that where there is a bend at the head of a valley, they produce an effect singularly resembling the seats of a roman amphitheatre. a good example of this configuration occurs near the town of melilli, as seen in the annexed view (fig. .). in the south of the island, near spaccaforno, scicli, and modica, precipitous rocks of white limestone, ascending to the height of feet, have been carved out into similar forms. [illustration: fig. . cross section.] this appearance of a range of marble seats circling round the head of a valley, or of great flights of steps descending from the top to the bottom, on the opposite sides of a gorge, may be accounted for, as already hinted, by supposing the sea to have stood successively at many different levels, as at _a a_, _b b_, _c c_, in the accompanying fig. . but the causes of the gradual contraction of the valley from above downwards may still be matter of speculation. such contraction may be due to the greater force exerted by the waves when the land at its first emergence was smaller in quantity, and more exposed to denudation in an open sea; whereas the wear and tear of the rocks might diminish in proportion as this action became confined within bays or channels closed in on two or three sides. or, secondly, the separate movements of elevation may have followed each other more rapidly as the land continued to rise, so that the times of those pauses, during which the greatest denudation was accomplished at certain levels, were always growing shorter. it should be remarked, that the cliffs and small terraces are rarely found on the opposite sides of the sicilian valleys at heights so precisely answering to each other as those given in fig. ., and this might have been expected, to whichever of the two hypotheses above explained we incline; for, according to the direction of the prevailing winds and currents, the waves may beat with unequal force on different parts of the shore, so that while no impression is made on one side of a bay, the sea may encroach so far on the other as to unite several smaller cliffs into one. before quitting the subject of ancient sea-cliffs, carved out of limestone, i shall mention the range of precipitous rocks, composed of a white marble of the oolitic period, which i have seen near the northern gate of st. mihiel in france. they are situated on the right bank of the meuse, at a distance of miles from the nearest sea, and they present on the precipice facing the river three or four horizontal grooves, one above the other, precisely resembling those which are scooped out by the undermining waves. the summits of several of these masses are detached from the adjoining hill, in which case the grooves pass all round them, facing towards all points of the compass, as if they had once formed rocky islets near the shore.[ -a] captain bayfield, in his survey of the gulf of st. lawrence, discovered in several places, especially in the mingan islands, a counterpart of the inland cliffs of st. mihiel, and traced a succession of shingle beaches, one above the other, which agreed in their level with some of the principal grooves scooped out of the limestone pillars. these beaches consisted of calcareous shingle, with shells of recent species, the farthest from the shore being feet above the level of the highest tides. in addition to the drawings of the pillars called the flower-pots, which he has published[ -b], i have been favoured with other views of rocks on the same coast, drawn by lieut. a. bowen, r. n. (see fig. .) [illustration: fig. . limestone columns in niapisca island, in the gulf of st. lawrence. height of the second column on the left, feet.] in the north-american beaches above mentioned rounded fragments of limestone have been found perforated by _lithodomi_; and holes drilled by the same mollusks have been detected in the columnar rocks or "flower-pots," showing that there has been no great amount of atmospheric decomposition on the surface, or the cavities alluded to would have disappeared. [illustration: fig. . the north rocks, bermuda, lying outside the great coral reef. a. feet high, and b. feet. _c._ _c._ hollows worn by the sea.] we have an opportunity of seeing in the bermuda islands the manner in which the waves of the atlantic have worn, and are now wearing out, deep smooth hollows on every side of projecting masses of hard limestone. in the annexed drawing, communicated to me by lieut. nelson, the excavations _c_, _c_, _c_, have been scooped out by the waves in a stone of very modern date, which, although extremely hard, is full of recent corals and shells, some of which retain their colour. when the forms of these horizontal grooves, of which the surface is sometimes smooth and almost polished, and the roofs of which often overhang to the extent of feet or more, have been carefully studied by geologists, they will serve to testify the former action of the waves at innumerable points far in the interior of the continents. but we must learn to distinguish the indentations due to the original action of the sea, and those caused by subsequent chemical decomposition of calcareous rocks, to which they are liable in the atmosphere. notwithstanding the enduring nature of the marks left by littoral action on calcareous rocks, we can by no means detect sea-beaches and inland cliffs everywhere, even in sicily and the morea. on the contrary, they are, upon the whole, extremely partial, and are often entirely wanting in districts composed of argillaceous and sandy formations, which must, nevertheless, have been upheaved at the same time, and by the same intermittent movements, as the adjoining calcareous rocks. footnotes: [ -a] western islands, vol. ii. p. . pl. . fig. . [ -a] see mammat's geological facts, &c. p. . and plate. [ -b] conybeare's report to brit. assoc. , p. . [ -a] prestwich, geol. trans. second series, vol. v. pp. . . [ -a] section given by dr. christie, edin. new phil. journ. no. xxiii., called by mistake the cave of mardolce, by the late m. hoffmann. see account by mr. s. p. pratt, f. g. s. proceedings of geol. soc. no. . . [ -a] i was directed by m. deshayes to this spot, which i visited in june, . [ -b] see trans. of geol. soc., second series, vol. v. plate v. chapter vii. alluvium. alluvium described--due to complicated causes--of various ages, as shown in auvergne--how distinguished from rocks in situ--river-terraces--parallel roads of glen roy--various theories respecting their origin. between the superficial covering of vegetable mould and the subjacent rock there usually intervenes in every district a deposit of loose gravel, sand, and mud, to which the name of alluvium has been applied. the term is derived from _alluvio_, an inundation, or _alluo_, to wash, because the pebbles and sand commonly resemble those of a river's bed or the mud and gravel spread over low lands by a flood. a partial covering of such alluvium is found alike in all climates, from the equatorial to the polar regions; but in the higher latitudes of europe and north america it assumes a distinct character, being very frequently devoid of stratification, and containing huge fragments of rock, some angular and others rounded, which have been transported to great distances from their parent mountains. when it presents itself in this form, it has been called "diluvium," "drift," or the "boulder formation;" and its probable connexion with the agency of floating ice and glaciers will be treated of more particularly in the eleventh and twelfth chapters. [illustration: fig. . lavas of auvergne resting on alluviums of different ages.] the student will be prepared, by what i have said in the last chapter on denudation, to hear that loose gravel and sand are often met with, not only on the low grounds bordering rivers, but also at various points on the sides or even summits of mountains. for, in the course of those changes in physical geography which may take place during the gradual emergence of the bottom of the sea and its conversion into dry land, any spot may either have been a sunken reef, or a bay, or estuary, or sea-shore, or the bed of a river. for this reason it would be unreasonable to hope that we should ever be able to account for all the alluvial phenomena of each particular country, seeing that the causes of their origin are so complicated. moreover, the last operations of water have a tendency to disturb and confound together all pre-existing alluviums. hence we are always in danger of regarding as the work of a single era, and the effect of one cause, what has in reality been the result of a variety of distinct agents, during a long succession of geological epochs. much useful instruction may therefore be gained from the exploration of a country like auvergne, where the superficial gravel of very different eras happens to have been preserved by sheets of lava, which were poured out one after the other at periods when the denudation, and probably the upheaval, of rocks were in progress. that region had already acquired in some degree its present configuration before any volcanos were in activity, and before any igneous matter was superimposed upon the granitic and fossiliferous formations. the pebbles therefore in the older gravels are exclusively constituted of granite and other aboriginal rocks; and afterwards, when volcanic vents burst forth into eruption, those earlier alluviums were covered by streams of lava, which protected them from intermixture with gravel of subsequent date. in the course of ages, a new system of valleys was excavated, so that the rivers ran at lower levels than those at which the first alluviums and sheets of lava were formed. when, therefore, fresh eruptions gave rise to new lava, the melted matter was poured out over lower grounds; and the gravel of these plains differed from the first or upland alluvium, by containing in it rounded fragments of various volcanic rocks, and often bones belonging to distinct groups of land animals which flourished in the country in succession. the annexed drawing will explain the different heights at which beds of lava and gravel, each distinct from the other in composition and age, are observed, some on the flat tops of hills, or feet high, others on the slope of the same hills, and the newest of all in the channel of the existing river where there is usually gravel alone, but in some cases a narrow stripe of solid lava sharing the bottom of the valley with the river. in all these accumulations of transported matter of different ages the bones of extinct quadrupeds have been found belonging to assemblages of land mammalia which flourished in the country in succession, and which vary specifically, the one from the other, in a greater or less degree, in proportion as the time which separated their entombment has been more or less protracted. the streams in the same district are still undermining their banks and grinding down into pebbles or sand, columns of basalt and fragments of granite and gneiss; but the older alluviums, with the fossil remains belonging to them, are prevented from being mingled with the gravel of recent date by the cappings of lava before mentioned. but for the accidental interference, therefore, of this peculiar cause, all the alluviums might have passed so insensibly the one into the other, that those formed at the remotest era might have appeared of the same date as the newest, and the whole formation might have been regarded by some geologists as the result of one sudden and violent catastrophe. in almost every country, the alluvium consists in its upper part of transported materials, but it often passes downwards into a mass of broken and angular fragments derived from the subjacent rock. to this mass the provincial name of "rubble," or "brash," is given in many parts of england. it may be referred to the weathering or disintegration of stone on the spot, the effects of air and water, sun and frost, and chemical decomposition. [illustration: fig. . cross section. _a._ vegetable soil. _b._ alluvium. _c._ mass of same, apparently detached.] the inferior surface of alluvial deposits is often very irregular, conforming to all the inequalities of the fundamental rocks (fig. .). occasionally, a small mass, as at _c_, appears detached, and as if included in the subjacent formation. such isolated portions are usually sections of winding subterranean hollows filled up with alluvium. they may have been the courses of springs or subterranean streamlets, which have flowed through and enlarged natural rents; or, when on a small scale and in soft strata, they may be spaces which the roots of large trees have once occupied, gravel and sand having been introduced after their decay. [illustration: fig. . sand-pipes in the chalk at eaton, near norwich.] but there are other deep hollows of a cylindrical form found in england, france, and elsewhere, penetrating the white chalk, and filled with sand and gravel, which are not so readily explained. they are sometimes called "sand-pipes," or "sand-galls," and "puits naturels," in france. those represented in the annexed cut were observed by me in , laid open in a large chalk-pit near norwich. they were of very symmetrical form, the largest more than feet in diameter, and some of them had been traced, by boring, to the depth of more than feet. the smaller ones varied from a few inches to a foot in diameter, and seldom descended more than feet below the surface. even where three of them occurred, as at _a_, fig. ., very close together, the parting walls of soft white chalk were not broken through. they all taper downwards and end in a point. as a general rule, sand and pebbles occupy the central parts of each pipe, while the sides and bottom are lined with clay. mr. trimmer, in speaking of appearances of the same kind in the kentish chalk, attributes the origin of such "sand-galls" to the action of the sea on a beach or shoal, where the waves, charged with shingle and sand, not only wear out longitudinal furrows, such as may be observed on the surface of the chalk near norwich when the incumbent gravel is removed, but also drill deep circular hollows by the rotatory motion imparted to sand and pebbles. such furrows, as well as vertical cavities, are now formed, he observes, on the coast where the shores are composed of chalk.[ -a] that the commencement of many of the tubular cavities now under consideration has been due to the cause here assigned, i have little doubt. but such mechanical action could not have hollowed out the whole of the sand-pipes _c_ and _d_, fig. ., because several large chalk-flints seen protruding from the walls of the pipes have not been eroded, while sand and gravel have penetrated many feet below them. in other cases, as at _b b_, similar unrounded nodules of flint, still preserving their irregular form and white coating, are found at various depths in the midst of the loose materials filling the pipe. these have evidently been detached from regular layers of flints occurring above. it is also to be remarked that the course of the same sand-pipe, _b b_, is traceable above the level of the chalk for some distance upwards, through the incumbent gravel and sand, by the obliteration of all signs of stratification. occasionally, also, as in the pipe _d_, the overlying beds of gravel bend downwards into the mouth of the pipe, so as to become in part vertical, as would happen if horizontal layers had sunk gradually in consequence of a failure of support. all these phenomena may be accounted for by attributing the enlargement and deepening of the sand-pipes to the chemical action of water charged with carbonic acid, derived from the vegetable soil and the decaying roots of trees. such acid might corrode the chalk, and deepen indefinitely any previously existing hollow, but could not dissolve the flints. the water, after it had become saturated with carbonate of lime, might freely percolate the surrounding porous walls of chalk, and escape through them and from the bottom of the tube, so as to carry away in the course of time large masses of dissolved calcareous rock[ -a], and leave behind it on the edges of each tubular hollow a coating of fine clay, which the white chalk contains. i have seen tubes precisely similar and from to feet in diameter traversing vertically the upper half of the soft calcareous building stone, or chalk without flints, constituting st. peter's mount, maestricht. these hollows are filled with pebbles and clay, derived from overlying beds of gravel, and all terminate downwards like those of norfolk. i was informed that, miles from maestricht, one of these pipes, feet in diameter, was traced downwards to a bed of flattened flints, forming an almost continuous layer in the chalk. here it terminated abruptly, but a few small root-like prolongations of it were detected immediately below, probably where the dissolving substance had penetrated at some points through openings in the siliceous mass. it is not so easy as may at first appear to draw a clear line of distinction between the _fixed_ rocks, or regular strata (rocks _in situ_ or _in place_), and _alluvium_. if the bed of a torrent or river be dried up, we call the gravel, sand, and mud left in their channels, or whatever, during floods, they may have scattered over the neighbouring plains, alluvium. the very same materials carried into a lake, where they become sorted by water and arranged in more distinct layers, especially if they inclose the remains of plants, shells, or other fossils, are termed regular strata. in like manner we may sometimes compare the gravel, sand, and broken shells, strewed along the path of a rapid marine current, with a deposit formed contemporaneously by the discharge of similar materials, year after year, into a deeper and more tranquil part of the sea. in such cases, when we detect marine shells or other organic remains entombed in the strata, which enable us to determine their age and mode of origin, we regard them as part of the regular series of fossiliferous formations, whereas, if there are no fossils, we have frequently no power of separating them from the general mass of superficial alluvium. the usual rarity of organic remains in beds of loose gravel and sand is partly owing to the rapid and turbid water in which they were formed having been in a condition unfavourable to the habitation of aquatic beings, and partly to their porous nature, which, by allowing the free percolation of rain-water, has promoted the decomposition and removal of organic matter. it has long been a matter of common observation that most rivers are now cutting their channels through alluvial deposits of greater depth and extent than could ever have been formed by the present streams. from this fact a rash inference has sometimes been drawn, that rivers in general have grown smaller, or become less liable to be flooded than formerly. but such phenomena would be a natural result of any considerable oscillations in the level of the land experienced since the existing valleys originated. suppose part of a continent, comprising within it a large hydrographical basin like that of the mississippi, to subside several inches or feet in a century, as the west coast of greenland, extending miles north and south, has been sinking for three or four centuries, between the latitudes ° and ° n.[ -a] there might be no encroachment of the sea at the river's mouth in consequence of this change of level, but the fall of the waters flowing from the interior being lessened, the main river and its tributaries would have less power to carry down to its delta, and to discharge into the ocean, the sedimentary matter with which they are annually loaded. they would all begin to raise their channels and alluvial plains by depositing in them the heavier sand and pebbles washed down from the upland country, and this operation would take place most effectively if the amount of subsidence in the interior was unequal, and especially if, on the whole, it exceeded that of the region near the sea. if then the same area of land be again upheaved to its former height, the fall, and consequently the velocity, of every river would begin to augment. each of them would be less given to overflow its alluvial plain; and their power of carrying earthy matter seaward, and of scouring out and deepening their channels, would continue till, after a lapse of many thousand years, each of them would have eroded a new channel or valley through a fluviatile formation of modern date. the surface of what was once the river-plain at the period of greatest depression, would remain fringing the valley sides in the form of a terrace apparently flat, but in reality sloping down with the general inclination of the river. everywhere this terrace would present cliffs of gravel and sand, facing the river. that such a series of movements has actually taken place in the main valley of the mississippi and in its tributary valleys during oscillations of level, i have endeavoured to show in my description of that country[ -a]; and the freshwater shells of existing species and bones of land quadrupeds, partly of extinct races preserved in the terraces of fluviatile origin, attest the exclusion of the sea during the whole process of filling up and partial re-excavation. in many cases, the alluvium in which rivers are now cutting their channels, originated when the land first rose out of the sea. if, for example, the emergence was caused by a gradual and uniform motion, every bay and estuary, or the straits between islands, would dry up slowly, and during their conversion into valleys, every part of the upheaved area would in its turn be a sea-shore, and might be strewed over with littoral sand and pebbles, or each spot might be the point where a delta accumulated during the retreat and exclusion of the sea. materials so accumulated would conform to the general slope of a valley from its head to the sea-coast. _river terraces._--we often observe at a short distance from the present bed of a river a steep cliff a few feet or yards high, and on a level with the top of it a flat terrace corresponding in appearance to the alluvial plain which immediately borders the river. this terrace is again bounded by another cliff, above which a second terrace sometimes occurs: and in this manner two or three ranges of cliffs and terraces are occasionally seen on one or both sides of the stream, the number varying, but those on the opposite sides often corresponding in height. [illustration: fig. . river terraces and parallel roads.] these terraces are seldom continuous for great distances, and their surface slopes downwards, with an inclination similar to that of the river. they are readily explained if we adopt the hypothesis before suggested, of a gradual rise of the land; especially if, while rivers are shaping out their beds, the upheaving movement be intermittent, so that long pauses shall occur, during which the stream will have time to encroach upon one of its banks, so as to clear away and flatten a large space. this operation being afterwards repeated at lower levels, there will be several successive cliffs and terraces. _parallel roads._--the parallel shelves, or roads, as they have been called, of lochaber or glen roy and other contiguous valleys in scotland, are distinct both in character and origin from the terraces above described; for they have no slope towards the sea like the channel of a river, nor are they the effect of denudation. glen roy is situated in the western highlands, about ten miles north of fort william, near the western end of the great glen of scotland, or caledonian canal, and near the foot of the highest of the grampians, ben nevis. throughout its whole length, a distance of more than ten miles, two, and in its lower part three, parallel roads or shelves are traced along the steep sides of the mountains, as represented in the annexed figure, fig. ., each maintaining a perfect horizontality, and continuing at exactly the same level on the opposite sides of the glen. seen at a distance, they appear like ledges or roads, cut artificially out of the sides of the hills; but when we are upon them we can scarcely recognize their existence, so uneven is their surface, and so covered with boulders. they are from to feet broad, and merely differ from the side of the mountain by being somewhat less steep. on closer inspection, we find that these terraces are stratified in the ordinary manner of alluvial or littoral deposits, as may be seen at those points where ravines have been excavated by torrents. the parallel shelves, therefore, have not been caused by denudation, but by the deposition of detritus, precisely similar to that which is dispersed in smaller quantities over the declivities of the hills above. these hills consist of clay-slate, mica-schist, and granite, which rocks have been worn away and laid bare at a few points only, in a line just above the parallel roads. the highest of these roads is about feet above the level of the sea, the next about feet lower than the uppermost, and the third still lower by about feet. it is only this last, or the lowest of the three, which is continued throughout glen spean, a large valley with which glen roy unites. as the shelves are always at the same height above the sea, they become continually more elevated above the river in proportion as we descend each valley; and they at length terminate very abruptly, without any obvious cause, either in the shape of the ground, or any change in the composition or hardness of the rocks. i should exceed the limits of this work, were i to attempt to give a full description of all the geographical circumstances attending these singular terraces, or to discuss the ingenious theories which have been severally proposed to account for them by dr. macculloch, sir t. d. lauder, and messrs. darwin, agassiz, milne, and chambers. there is one point, however, on which all are agreed, namely, that these shelves are ancient beaches, or littoral formations accumulated round the edges of one or more sheets of water which once stood at the level, first of the highest shelf, and successively at the height of the two others. it is well known, that wherever a lake or marine fiord exists surrounded by steep mountains subject to disintegration by frost or the action of torrents, some loose matter is washed down annually, especially during the melting of snow, and a check is given to the descent of this detritus at the point where it reaches the waters of the lake. the waves then spread out the materials along the shore, and throw some of them upon the beach; their dispersing power being aided by the ice, which often adheres to pebbles during the winter months, and gives buoyancy to them. the annexed diagram illustrates the manner in which dr. macculloch and mr. darwin suppose "the roads" to constitute mere indentations in a superficial alluvial coating which rests upon the hillside, and consists chiefly of clay and sharp unrounded stones. [illustration: fig. . cross section. a b. supposed original surface of rock. c d. roads or shelves in the outer alluvial covering of the hill.] among other proofs that the parallel roads have really been formed along the margin of a sheet of water, it may be mentioned, that wherever an isolated hill rises in the middle of the glen above the level of any particular shelf, a corresponding shelf is seen at the same level passing round the hill, as would have happened if it had once formed an island in a lake or fiord. another very remarkable peculiarity in these terraces is this; each of them comes in some portion of its course to a _col_, or passage between the heads of glens, the explanation of which will be considered in the sequel. those writers who first advocated the doctrine that the roads were the ancient beaches of freshwater lakes, were unable to offer any probable hypothesis respecting the formation and subsequent removal of barriers of sufficient height and solidity to dam up the water. to introduce any violent convulsion for their removal was inconsistent with the uninterrupted horizontality of the roads, and with the undisturbed aspect of those parts of the glens where the shelves come suddenly to an end. mr. agassiz and dr. buckland, desirous, like the defenders of the lake theory, to account for the limitation of the shelves to certain glens, and their absence in contiguous glens, where the rocks are of the same composition, and the slope and inclination of the ground very similar, started the conjecture that these valleys were once blocked up by enormous glaciers descending from ben nevis, giving rise to what are called in switzerland and in the tyrol, glacier-lakes. after a time the icy barrier was broken down, or melted, first, to the level of the second, and afterwards to that of the third road or shelf. in corroboration of this view, they contended that the alluvium of glen roy, as well as of other parts of scotland, agrees in character with the moraines of glaciers seen in the alpine valleys of switzerland. allusion will be made in the eleventh chapter to the former existence of glaciers in the grampians: in the mean time it will readily be conceded that this hypothesis is preferable to any previous lacustrine theory, by accounting more easily for the temporary existence and entire disappearance of lofty transverse barriers, although the height required for the imaginary dams of ice may be startling. before the idea last alluded to had been entertained, mr. darwin examined glen roy, and came to the opinion that the shelves were formed when the glens were still arms of the sea, and, consequently, that there never were any barriers. according to him, the land emerged during a slow and uniform upward movement, like that now experienced throughout a large part of sweden and finland; but there were certain pauses in the upheaving process, at which times the waters of the sea remained stationary for so many centuries as to allow of the accumulation of an extraordinary quantity of detrital matter, and the excavation, at points immediately above, of many deep notches and bare cliffs in the hard and solid rock. the phenomena which are most difficult to reconcile with this theory are, first, the abrupt cessation of the roads at certain points in the different glens; secondly, their unequal number in different valleys connecting with each other, there being three, for example, in glen roy and only one in glen spean; thirdly, the precise horizontality of level maintained by the same shelf over a space many leagues in length requiring us to assume, that during a rise of feet no one portion of the land was raised even a few yards above another; fourthly, the coincidence of level already alluded to of each shelf with a _col_, or the point forming the head of two glens, from which the rain-waters flow in opposite directions. this last-mentioned feature in the physical geography of lochaber seems to have been explained in a satisfactory manner by mr. darwin. he calls these _cols_ "landstraits," and regards them as having been anciently sounds or channels between islands. he points out that there is a tendency in such sounds to be silted up, and always the more so in proportion to their narrowness. in a chart of the falkland islands by capt. sullivan, r.n., it appears that there are several examples there of straits where the soundings diminish regularly towards the narrowest part. one is so nearly dry that it can be walked over at low water, and another, no longer covered by the sea, is supposed to have recently dried up in consequence of a small shift in the relative level of sea and land. "similar straits," observes mr. chambers, "hovering, in character, between sea and land, and which may be called fords, are met with in the hebrides. such, for example, is the passage dividing the islands of lewis and harris, and that between north uist and benbecula, both of which would undoubtedly appear as _cols_, coinciding with a terrace or raised beach, all round the islands, if the sea were to subside."[ -a] the precise horizontality of level maintained by the roads or shelves of lochaber over an area many leagues in length and breadth, is a difficulty common in some degree to all the rival hypotheses, whether of lakes, or glaciers, or of the simple upheaval of the land above the sea. for we cannot suppose the roads to be more ancient than the glacial period, or the era of the boulder formation of scotland, of which i shall speak in the eleventh and twelfth chapters. strata of that era of marine origin containing northern shells of existing species have been found at various heights in scotland, some on the east, and others on the west coast, from to feet high; and in one region in lanarkshire not less than feet above high-water mark. it seems, therefore, in the highest degree improbable that glen roy should have escaped entirely the upward movement experienced in so many surrounding regions,--a movement implied by the position of these marine deposits, in which the shells are almost all of known recent species. but if the motion has really extended to glen roy and the contiguous glens, it must have uplifted them bodily, without in the slightest degree affecting their horizontality; and this being admitted, the principal objection to the theory of marine beaches, founded on the uniformity of upheaval, is removed, or is at least common to every theory hitherto proposed. to assume that the ocean has gone down from the level of the uppermost shelf, or feet, simultaneously all over the globe, while the land remained unmoved, is a view which will find favour with very few geologists, for the reasons explained in the fifth chapter. the student will perceive, from the above sketch of the controversy respecting the formation of these curious shelves, that this problem, like many others in geology, is as yet only solved in part; and that a larger number of facts must be collected and reasoned upon before the question can be finally settled. footnotes: [ -a] trimmer, proceedings of geol. soc. vol. iv. p. . . [ -a] see lyell on sand-pipes, &c., phil. mag., third series, vol. xv. p. ., oct. . [ -a] principles of geology, th ed. p. ., th ed. . [ -a] second visit to the u. s. vol. ii. chap. . [ -a] "ancient sea margins," p. ., by r. chambers. chapter viii. chronological classification of rocks. aqueous, plutonic, volcanic, and metamorphic rocks, considered chronologically--lehman's division into primitive and secondary--werner's addition of a transition class--neptunian theory--hutton on igneous origin of granite--how the name of primary was still retained for granite--the term "transition," why faulty--the adherence to the old chronological nomenclature retarded the progress of geology--new hypothesis invented to reconcile the igneous origin of granite to the notion of its high antiquity--explanation of the chronological nomenclature adopted in this work, so far as regards primary, secondary, and tertiary periods. in the first chapter it was stated that the four great classes of rocks, the aqueous, the volcanic, the plutonic, and the metamorphic, would each be considered not only in reference to their mineral characters, and mode of origin, but also to their relative age. the preservation of the shelves may have required, says darwin, the quick growth of green turf on a good soil; their abrupt cessation may mark the place where the soil was barren, and when a green sward formed slowly. in regard to the aqueous rocks, we have already seen that they are stratified, that some are calcareous, others argillaceous or siliceous, some made up of sand, others of pebbles; that some contain freshwater, others marine fossils, and so forth; but the student has still to learn which rocks, exhibiting some or all of these characters, have originated at one period of the earth's history, and which at another. to determine this point in reference to the fossiliferous formations is more easy than in any other class, and it is therefore the most convenient and natural method to begin by establishing a chronology for these fossiliferous strata, and then to endeavour to refer to the same divisions, the several groups of plutonic, volcanic, and metamorphic rocks. this system of classification is not only recommended by its greater clearness and facility of application, but is also best fitted to strike the imagination by bringing into one view the past changes of the inorganic world, and the contemporaneous revolutions of the organic creation. for the sedimentary formations of successive periods are most readily distinguished by the different species of fossil animals and plants which they inclose, and of which one race after another has flourished and then disappeared from the earth. but before entering specially on the subdivisions of the aqueous rocks arranged according to the order of time, it will be desirable to say a few words on the chronology of rocks in general, although in doing so we shall be unavoidably led to allude to some classes of phenomena which the beginner must not yet expect fully to comprehend. it was for many years a received opinion, that the formation of entire families of rocks, such as the plutonic and those crystalline schists spoken of in the first chapter as metamorphic, began and ended before any members of the aqueous and volcanic orders were produced; and although this idea has long been modified, and is nearly exploded, it will be necessary to give some account of the ancient doctrine, in order that beginners may understand whence many prevailing opinions, and some part of the nomenclature of geology, still partially in use, was derived. about the middle of the last century, lehman, a german miner, proposed to divide rocks into three classes, the first and oldest to be called primitive, comprising the hypogene, or plutonic and metamorphic rocks; the next to be termed secondary, comprehending the aqueous or fossiliferous strata; and the remainder, or third class, corresponding to our alluvium, ancient and modern, which he referred to "local floods, and the deluge of noah." in the primitive class, he said, such as granite and gneiss, there are no organic remains, nor any signs of materials derived from the ruins of pre-existing rocks. their origin, therefore, may have been purely chemical, antecedent to the creation of living beings, and probably coeval with the birth of the world itself. the secondary formations, on the contrary, which often contain sand, pebbles, and organic remains, must have been mechanical deposits, produced after the planet had become the habitation of animals and plants. this bold generalization, although anticipated in some measure by steno, a century before, in italy, formed at the time an important step in the progress of geology, and sketched out correctly some of the leading divisions into which rocks may be separated. about half a century later, werner, so justly celebrated for his improved methods of discriminating the mineralogical characters of rocks, attempted to improve lehman's classification, and with this view intercalated a class, called by him "the transition formations," between the primitive and secondary. between these last he had discovered, in northern germany, a series of strata, which in their mineral peculiarities were of an intermediate character, partaking in some degree of the crystalline nature of micaceous schist and clay-slate, and yet exhibiting here and there signs of a mechanical origin and organic remains. for this group, therefore, forming a passage between lehman's primitive and secondary rocks, the name of _übergang_ or transition was proposed. they consisted principally of clay-slate and an argillaceous sandstone, called grauwacke, and partly of calcareous beds. it happened in the district which werner first investigated, that both the primitive and transition strata were highly inclined, while the beds of the newer fossiliferous rocks, the secondary of lehman, were horizontal. to these latter, therefore, he gave the name _flötz_, or "a level floor;" and every deposit more modern than the chalk, which was classed as the uppermost of the flötz series, was designated "the overflowed land," an expression which may be regarded as equivalent to alluvium, although under this appellation were confounded all the strata afterwards called tertiary, of which werner had scarcely any knowledge. as the followers of werner soon discovered that the inclined position of the "transition beds," and the horizontality of the flötz, or newer fossiliferous strata, were mere local accidents, they soon abandoned the term flötz; and the four divisions of the wernerian school were then named primitive, transition, secondary, and alluvial. as to the trappean rocks, although their igneous origin had been already demonstrated by arduino, fortis, faujas, and others, and especially by desmarest, they were all regarded by werner as aqueous, and as mere subordinate members of the secondary series.[ -a] this theory of werner's was called the "neptunian," and for many years enjoyed much popularity. it assumed that the globe had been at first invested by an universal chaotic ocean, holding the materials of all rocks in solution. from the waters of this ocean, granite, gneiss, and other crystalline formations, were first precipitated; and afterwards, when the waters were purged of these ingredients, and more nearly resembled those of our actual seas, the transition strata were deposited. these were of a mixed character, not purely chemical, because the waves and currents had already begun to wear down solid land, and to give rise to pebbles, sand, and mud; nor entirely without fossils, because a few of the first marine animals had begun to exist. after this period, the secondary formations were accumulated in waters resembling those of the present ocean, except at certain intervals, when, from causes wholly unexplained, a partial recurrence of the "chaotic fluid" took place, during which various trap rocks, some highly crystalline, were formed. this arbitrary hypothesis rejected all intervention of igneous agency, volcanos being regarded as modern, partial, and superficial accidents, of trifling account among the great causes which have modified the external structure of the globe. meanwhile hutton, a contemporary of werner, began to teach, in scotland, that granite as well as trap was of igneous origin, and had at various periods intruded itself in a fluid state into different parts of the earth's crust. he recognized and faithfully described many of the phenomena of granitic veins, and the alterations produced by them on the invaded strata, which will be treated of in the thirty-second chapter. he, moreover, advanced the opinion, that the crystalline strata called primitive had not been precipitated from a primæval ocean, but were sedimentary strata altered by heat. in his writings, therefore, and in those of his illustrator, playfair, we find the germ of that metamorphic theory which has been already hinted at in the first chapter, and which will be more fully expounded in the thirty-fourth and thirty-fifth chapters. at length, after much controversy, the doctrine of the igneous origin of trap and granite made its way into general favour; but although it was, in consequence, admitted that both granite and trap had been produced at many successive periods, the term primitive or primary still continued to be applied to the crystalline formations in general, whether stratified, like gneiss, or unstratified, like granite. the pupil was told that granite was a primary rock, but that some granites were newer than certain secondary formations; and in conformity with the spirit of the ancient language, to which the teacher was still determined to adhere, a desire was naturally engendered of extenuating the importance of those more modern granites, the true dates of which new observations were continually bringing to light. a no less decided inclination was shown to persist in the use of the term "transition," after it had been proved to be almost as faulty in its original application as that of flötz. the name of transition, as already stated, was first given by werner, to designate a mineral character, intermediate between the highly crystalline or metamorphic state and that of an ordinary fossiliferous rock. but the term acquired also from the first a chronological import, because it had been appropriated to sedimentary formations, which, in the hartz and other parts of germany, were more ancient than the oldest of the secondary series, and were characterized by peculiar fossil zoophytes and shells. when, therefore, geologists found in other districts stratified rocks occupying the same position, and inclosing similar fossils, they gave to them also the name of _transition_, according to rules which will be explained in the next chapter; yet, in many cases, such rocks were found not to exhibit the same mineral texture which werner had called transition. on the contrary, many of them were not more crystalline than different members of the secondary class; while, on the other hand, these last were sometimes found to assume a semi-crystalline and almost metamorphic aspect, and thus, on lithological grounds, to deserve equally the name of transition. so remarkably was this the case in the swiss alps, that certain rocks, which had for years been regarded by some of the most skilful disciples of werner to be transition, were at last acknowledged, when their relative position and fossils were better understood, to belong to the newest of the secondary groups; nay, some of them have actually been discovered to be members of the lower tertiary series! if, under such circumstances, the name of transition was retained, it is clear that it ought to have been applied without reference to the age of strata, and simply as expressive of a mineral peculiarity. the continued appropriation of the term to formations of a given date, induced geologists to go on believing that the ancient strata so designated bore a less resemblance to the secondary than is really the case, and to imagine that these last never pass, as they frequently do, into metamorphic rocks. the poet waller, when lamenting over the antiquated style of chaucer, complains that-- we write in sand, our language grows, and, like the tide, our work o'erflows. but the reverse is true in geology; for here it is our work which continually outgrows the language. the tide of observation advances with such speed that improvements in theory outrun the changes of nomenclature; and the attempt to inculcate new truths by words invented to express a different or opposite opinion, tends constantly, by the force of association, to perpetuate error; so that dogmas renounced by the reason still retain a strong hold upon the imagination. in order to reconcile the old chronological views with the new doctrine of the igneous origin of granite, the following hypothesis was substituted for that of the neptunists. instead of beginning with an aqueous menstruum or chaotic fluid, the materials of the present crust of the earth were supposed to have been at first in a state of igneous fusion, until part of the heat having been diffused into surrounding space, the surface of the fluid consolidated, and formed a crust of granite. this covering of crystalline stone, which afterwards grew thicker and thicker as it cooled, was so hot, at first, that no water could exist upon it; but as the refrigeration proceeded, the aqueous vapour in the atmosphere was condensed, and, falling in rain, gave rise to the first _thermal ocean_. so high was the temperature of this boiling sea, that no aquatic beings could inhabit its waters, and its deposits were not only devoid of fossils, but, like those of some hot springs, were highly crystalline. hence the origin of the primary or crystalline strata,--gneiss, mica-schist, and the rest. afterwards, when the granitic crust had been partially broken up, land and mountains began to rise above the waters, and rains and torrents ground down rock, so that sediment was spread over the bottom of the seas. yet the heat still remaining in the solid supporting substances was sufficient to increase the chemical action exerted by the water, although not so intense as to prevent the introduction and increase of some living beings. during this state of things some of the residuary mineral ingredients of the primæval ocean were precipitated, and formed deposits (the transition strata of werner), half chemical and half mechanical, and containing a few fossils. by this new theory, which was in part a revival of the doctrine of leibnitz, published in , on the igneous origin of the planet, the old ideas respecting the priority of all crystalline rocks to the creation of organic beings, were still preserved; and the mistaken notion that all the semi-crystalline and partially fossiliferous rocks belonged to one period, while all the earthy and uncrystalline formations originated at a subsequent epoch, was also perpetuated. it may or may not be true, as the great leibnitz imagined, that the whole planet was once in a state of liquefaction by heat; but there are certainly no geological proofs that the granite which constitutes the foundation of so much of the earth's crust was ever at once in a state of universal fusion. on the contrary, all our evidence tends to show that the formation of granite, like the deposition of the stratified rocks, has been successive, and that different portions of granite have been in a melted state at distinct and often distant periods. one mass was solid, and had been fractured, before another body of granitic matter was injected into it, or through it, in the form of veins. some granites are more ancient than any known fossiliferous rocks; others are of secondary; and some, such as that of mont blanc and part of the central axis of the alps, of tertiary origin. in short, the universal fluidity of the crystalline foundations of the earth's crust, can only be understood in the same sense as the universality of the ancient ocean. all the land has been under water, but not all at one time; so all the subterranean unstratified rocks to which man can obtain access have been melted, but not simultaneously. in the present work the four great classes of rocks, the aqueous, plutonic, volcanic, and metamorphic, will form four parallel, or nearly parallel, columns in one chronological table. they will be considered as four sets of monuments relating to four contemporaneous, or nearly contemporaneous, series of events. i shall endeavour, in a subsequent chapter on the plutonic rocks, to explain the manner in which certain masses belonging to each of the four classes of rocks may have originated simultaneously at every geological period, and how the earth's crust may have been continually remodelled, above and below, by aqueous and igneous causes, from times indefinitely remote. in the same manner as aqueous and fossiliferous strata are now formed in certain seas or lakes, while in other places volcanic rocks break out at the surface, and are connected with reservoirs of melted matter at vast depths in the bowels of the earth,--so, at every era of the past, fossiliferous deposits and superficial igneous rocks were in progress contemporaneously with others of subterranean and plutonic origin, and some sedimentary strata were exposed to heat and made to assume a crystalline or metamorphic structure. it can by no means be taken for granted, that during all these changes the solid crust of the earth has been increasing in thickness. it has been shown, that so far as aqueous action is concerned, the gain by fresh deposits, and the loss by denudation, must at each period have been equal (see above, p. .); and in like manner, in the inferior portion of the earth's crust, the acquisition of new crystalline rocks, at each successive era, may merely have counter-balanced the loss sustained by the melting of materials previously consolidated. as to the relative antiquity of the crystalline foundations of the earth's crust, when compared to the fossiliferous and volcanic rocks which they support, i have already stated, in the first chapter, that to pronounce an opinion on this matter is as difficult as at once to decide which of the two, whether the foundations or superstructure of an ancient city built on wooden piles, may be the oldest. we have seen that, to answer this question, we must first be prepared to say whether the work of decay and restoration had gone on most rapidly above or below, whether the average duration of the piles has exceeded that of the stone buildings, or the contrary. so also in regard to the relative age of the superior and inferior portions of the earth's crust; we cannot hazard even a conjecture on this point, until we know whether, upon an average, the power of water above, or that of heat below, is most efficacious in giving new forms to solid matter. after the observations which have now been made, the reader will perceive that the term primary must either be entirely renounced, or, if retained, must be differently defined, and not made to designate a set of crystalline rocks, some of which are already ascertained to be newer than all the secondary formations. in this work i shall follow most nearly the method proposed by mr. boué, who has called all _fossiliferous_ rocks older than the secondary by the name of primary. to prevent confusion, however, i shall always speak of these, when they are of the aqueous class, as the _primary fossiliferous_ formations, because the word primary has hitherto been almost inseparably connected with the idea of a non-fossiliferous rock. if we can prove any plutonic, volcanic, or metamorphic rocks to be older than the secondary formations, such rocks will also be primary, according to this system. mr. boué having with great propriety excluded the metamorphic rocks, _as a class_, from the primary formations, proposed to call them all "crystalline schists." as there are secondary fossiliferous strata, so we shall find that there are plutonic, volcanic, and metamorphic rocks of contemporaneous origin, which i shall also term secondary. in the next chapter it will be shown that the strata above the chalk have been called tertiary. if, therefore, we discover any volcanic, plutonic, or metamorphic rocks, which have originated since the deposition of the chalk, these also will rank as tertiary formations. it may perhaps be suggested that some metamorphic strata, and some granites, may be anterior in date to the oldest of the primary fossiliferous rocks. this opinion is doubtless true, and will be discussed in future chapters; but i may here observe, that when we arrange the four classes of rocks in four parallel columns in one table of chronology, it is by no means assumed that these columns are all of equal length; one may begin at an earlier period than the rest, and another may come down to a later point of time. in the small part of the globe hitherto examined, it is hardly to be expected that we should have discovered either the oldest or the newest members of each of the four classes of rocks. thus, if there be primary, secondary, and tertiary rocks of the aqueous or fossiliferous class, and in like manner primary, secondary, and tertiary hypogene formations, we may not be yet acquainted with the most ancient of the primary fossiliferous beds, or with the newest of the hypogene. footnotes: [ -a] see principles, vol. i. chap. iv. chapter ix. on the different ages of the aqueous rocks. on the three principal tests of relative age--superposition, mineral character, and fossils--change of mineral character and fossils in the same continuous formation--proofs that distinct species of animals and plants have lived at successive periods--distinct provinces of indigenous species--great extent of single provinces--similar laws prevailed at successive geological periods--relative importance of mineral and palæontological characters--test of age by included fragments--frequent absence of strata of intervening periods--principal groups of strata in western europe. in the last chapter i spoke generally of the chronological relations of the four great classes of rocks, and i shall now treat of the aqueous rocks in particular, or of the successive periods at which the different fossiliferous formations have been deposited. there are three principal tests by which we determine the age of a given set of strata; first, superposition; secondly, mineral character; and, thirdly, organic remains. some aid can occasionally be derived from a fourth kind of proof, namely, the fact of one deposit including in it fragments of a pre-existing rock, by which the relative ages of the two may, even in the absence of all other evidence, be determined. _superposition._--the first and principal test of the age of one aqueous deposit, as compared to another, is relative position. it has been already stated, that where strata are horizontal, the bed which lies uppermost is the newest of the whole, and that which lies at the bottom the most ancient. so, of a series of sedimentary formations, they are like volumes of history, in which each writer has recorded the annals of his own times, and then laid down the book, with the last written page uppermost, upon the volume in which the events of the era immediately preceding were commemorated. in this manner a lofty pile of chronicles is at length accumulated; and they are so arranged as to indicate, by their position alone, the order in which the events recorded in them have occurred. in regard to the crust of the earth, however, there are some regions where, as the student has already been informed, the beds have been disturbed, and sometimes extensively thrown over and turned upside down. (see pp. , .) but an experienced geologist can rarely be deceived by these exceptional cases. when he finds that the strata are fractured, curved, inclined, or vertical, he knows that the original order of superposition must be doubtful, and he then endeavours to find sections in some neighbouring district where the strata are horizontal, or only slightly inclined. here the true order of sequence of the entire series of deposits being ascertained, a key is furnished for settling the chronology of those strata where the displacement is extreme. _mineral character._--the same rocks may often be observed to retain for miles, or even hundreds of miles, the same mineral peculiarities, if we follow the planes of stratification, or trace the beds, if they be undisturbed, in a horizontal direction. but if we pursue them vertically, or in any direction transverse to the planes of stratification, this uniformity ceases almost immediately. in that case we can scarcely ever penetrate a stratified mass for a few hundred yards without beholding a succession of extremely dissimilar, calcareous, argillaceous, and siliceous rocks. these phenomena lead to the conclusion, that rivers and currents have dispersed the same sediment over wide areas at one period, but at successive periods have been charged, in the same region, with very different kinds of matter. the first observers were so astonished at the vast spaces over which they were able to follow the same homogeneous rocks in a horizontal direction, that they came hastily to the opinion, that the whole globe had been environed by a succession of distinct aqueous formations, disposed round the nucleus of the planet, like the concentric coats of an onion. but although, in fact, some formations may be continuous over districts as large as half of europe, or even more, yet most of them either terminate wholly within narrower limits, or soon change their lithological character. sometimes they thin out gradually, as if the supply of sediment had failed in that direction, or they come abruptly to an end, as if we had arrived at the borders of the ancient sea or lake which served as their receptacle. it no less frequently happens that they vary in mineral aspect and composition, as we pursue them horizontally. for example, we trace a limestone for a hundred miles, until it becomes more arenaceous, and finally passes into sand, or sandstone. we may then follow this sandstone, already proved by its continuity to be of the same age, throughout another district a hundred miles or more in length. _organic remains._--this character must be used as a criterion of the age of a formation, or of the contemporaneous origin of two deposits in distant places, under very much the same restrictions as the test of mineral composition. first, the same fossils may be traced over wide regions, if we examine strata in the direction of their planes, although by no means for indefinite distances. secondly, while the same fossils prevail in a particular set of strata for hundreds of miles in a horizontal direction, we seldom meet with the same remains for many fathoms, and very rarely for several hundred yards, in a vertical line, or a line transverse to the strata. this fact has now been verified in almost all parts of the globe, and has led to a conviction, that at successive periods of the past, the same area of land and water has been inhabited by species of animals and plants even more distinct than those which now people the antipodes, or which now co-exist in the arctic, temperate, and tropical zones. it appears, that from the remotest periods there has been ever a coming in of new organic forms, and an extinction of those which pre-existed on the earth; some species having endured for a longer, others for a shorter, time; while none have ever reappeared after once dying out. the law which has governed the creation and extinction of species seems to be expressed in the verse of the poet,-- natura il fece, e poi ruppe la stampa. ariosto. nature made him, and then broke the die. and this circumstance it is, which confers on fossils their highest value as chronological tests, giving to each of them, in the eyes of the geologist, that authority which belongs to contemporary medals in history. the same cannot be said of each peculiar variety of rock; for some of these, as red marl and red sandstone, for example, may occur at once at the top, bottom, and middle of the entire sedimentary series; exhibiting in each position so perfect an identity of mineral aspect as to be undistinguishable. such exact repetitions, however, of the same mixtures of sediment have not often been produced, at distant periods, in precisely the same parts of the globe; and even where this has happened, we are seldom in any danger of confounding together the monuments of remote eras, when we have studied their imbedded fossils and relative position. it was remarked that the same species of organic remains cannot be traced horizontally, or in the direction of the planes of stratification for indefinite distances. this might have been expected from analogy; for when we inquire into the present distribution of living beings, we find that the habitable surface of the sea and land may be divided into a considerable number of distinct provinces, each peopled by a peculiar assemblage of animals and plants. in the principles of geology, i have endeavoured to point out the extent and probable origin of these separate divisions; and it was shown that climate is only one of many causes on which they depend, and that difference of longitude as well as latitude is generally accompanied by a dissimilarity of indigenous species. as different seas, therefore, and lakes are inhabited at the same period, by different aquatic animals and plants, and as the lands adjoining these may be peopled by distinct terrestrial species, it follows that distinct fossils will be imbedded in contemporaneous deposits. if it were otherwise--if the same species abounded in every climate, or in every part of the globe where, so far as we can discover, a corresponding temperature and other conditions favourable to their existence are found--the identification of mineral masses of the same age, by means of their included organic contents, would be a matter of still greater certainty. nevertheless, the extent of some single zoological provinces, especially those of marine animals, is very great; and our geological researches have proved that the same laws prevailed at remote periods; for the fossils are often identical throughout wide spaces, and in a great number of detached deposits, in which the mineral nature of the rocks is variable. the doctrine here laid down will be more readily understood, if we reflect on what is now going on in the mediterranean. that entire sea may be considered as one zoological province; for, although certain species of testacea and zoophytes may be very local, and each region has probably some species peculiar to it, still a considerable number are common to the whole mediterranean. if, therefore, at some future period, the bed of this inland sea should be converted into land, the geologist might be enabled, by reference to organic remains, to prove the contemporaneous origin of various mineral masses scattered over a space equal in area to the half of europe. deposits, for example, are well known to be now in progress in this sea in the deltas of the po, rhone, nile, and other rivers, which differ as greatly from each other in the nature of their sediment as does the composition of the mountains which they drain. there are also other quarters of the mediterranean, as off the coast of campania, or near the base of etna, in sicily, or in the grecian archipelago, where another class of rocks is now forming; where showers of volcanic ashes occasionally fall into the sea, and streams of lava overflow its bottom; and where, in the intervals between volcanic eruptions, beds of sand and clay are frequently derived from the waste of cliffs, or the turbid waters of rivers. limestones, moreover, such as the italian travertins, are here and there precipitated from the waters of mineral springs, some of which rise up from the bottom of the sea. in all these detached formations, so diversified in their lithological characters, the remains of the same shells, corals, crustacea, and fish are becoming inclosed; or, at least, a sufficient number must be common to the different localities to enable the zoologist to refer them all to one contemporaneous assemblage of species. there are, however, certain combinations of geographical circumstances which cause distinct provinces of animals and plants to be separated from each other by very narrow limits; and hence it must happen, that strata will be sometimes formed in contiguous regions, differing widely both in mineral contents and organic remains. thus, for example, the testacea, zoophytes, and fish of the red sea are, as a group, extremely distinct from those inhabiting the adjoining parts of the mediterranean, although the two seas are separated only by the narrow isthmus of suez. of the bivalve shells, according to philippi, not more than a fifth are common to the red sea and the sea around sicily, while the proportion of univalves (or gasteropoda) is still smaller, not exceeding eighteen in a hundred. calcareous formations have accumulated on a great scale in the red sea in modern times, and fossil shells of existing species are well preserved therein; and we know that at the mouth of the nile large deposits of mud are amassed, including the remains of mediterranean species. it follows, therefore, that if at some future period the bed of the red sea should be laid dry, the geologist might experience great difficulties in endeavouring to ascertain the relative age of these formations, which, although dissimilar both in organic and mineral characters, were of synchronous origin. but, on the other hand, we must not forget that the north-western shores of the arabian gulf, the plains of egypt, and the isthmus of suez, are all parts of one province of _terrestrial_ species. small streams, therefore, occasional land-floods, and those winds which drift clouds of sand along the deserts, might carry down into the red sea the same shells of fluviatile and land testacea which the nile is sweeping into its delta, together with some remains of terrestrial plants and the bones of quadrupeds, whereby the groups of strata, before alluded to, might, notwithstanding the discrepancy of their mineral composition and _marine_ organic fossils, be shown to have belonged to the same epoch. yet while rivers may thus carry down the same fluviatile and terrestrial spoils into two or more seas inhabited by different marine species, it will much more frequently happen, that the co-existence of terrestrial species of distinct zoological and botanical provinces will be proved by the identity of the marine beings which inhabited the intervening space. thus, for example, the land quadrupeds and shells of the south of europe, north of africa, and north-west of asia, are different, yet their remains are all washed down by rivers flowing from these three countries into the mediterranean. in some parts of the globe, at the present period, the line of demarcation between distinct provinces of animals and plants is not very strongly marked, especially where the change is determined by temperature, as in seas extending from the temperate to the tropical zone, or from the temperate to the arctic regions. here a gradual passage takes place from one set of species to another. in like manner the geologist, in studying particular formations of remote periods, has sometimes been able to trace the gradation from one ancient province to another, by observing carefully the fossils of all the intermediate places. his success in thus acquiring a knowledge of the zoological or botanical geography of very distant eras has been mainly owing to this circumstance, that the mineral character has no tendency to be affected by climate. a large river may convey yellow or red mud into some part of the ocean, where it may be dispersed by a current over an area several hundred leagues in length, so as to pass from the tropics into the temperate zone. if the bottom of the sea be afterwards upraised, the organic remains imbedded in such yellow or red strata may indicate the different animals or plants which once inhabited at the same time the temperate and equatorial regions. it may be true, as a general rule, that groups of the same species of animals and plants may extend over wider areas than deposits of homogeneous composition; and if so, palæontological characters will be of more importance in geological classification than mineral composition; but it is idle to discuss the relative value of these tests, as the aid of both is indispensable, and it fortunately happens, that where the one criterion fails, we can often avail ourselves of the other. _test by included fragments of older rocks._--it was stated, that independent proof may sometimes be obtained of the relative date of two formations, by fragments of an older rock being included in a newer one. this evidence may sometimes be of great use, where a geologist is at a loss to determine the relative age of two formations from want of clear sections exhibiting their true order of position, or because the strata of each group are vertical. in such cases we sometimes discover that the more modern rock has been in part derived from the degradation of the older. thus, for example, we may find in one part of a country chalk with flints; and, in another, a distinct formation, consisting of alternations of clay, sand, and pebbles. if some of these pebbles consist of similar flint and fossil shells, sponges, and foraminiferæ, of the same species as those in the chalk, we may confidently infer that the chalk is the oldest of the two formations. _chronological groups._--the number of groups into which the fossiliferous strata may be separated are more or less numerous, according to the views of classification which different geologists entertain; but when we have adopted a certain system of arrangement, we immediately find that a few only of the entire series of groups occur one upon the other in any single section or district. [illustration: fig. . block section.] the thinning out of individual strata was before described (p. .). but let the annexed diagram represent seven fossiliferous groups, instead of as many strata. it will then be seen that in the middle all the superimposed formations are present; but in consequence of some of them thinning out, no. . and no. . are absent at one extremity of the section, and no. . at the other. [illustration: fig. . section south of bristol. a. c. ramsay. length of section miles. _a_, _b_. level of the sea. . inferior oolite. . lias. . new red sandstone. . magnesian conglomerate. . coal measure. . carboniferous limestone. . old red sandstone.] in the annexed diagram, fig. ., a real section of the geological formations in the neighbourhood of bristol and the mendip hills, is presented to the reader as laid down on a true scale by professor ramsay, where the newer groups , , , . rest unconformably on the formations and . here at the southern end of the line of section we meet with the beds no. . (the new red sandstone) resting immediately on no. ., while farther north, as at dundry hill, we behold six groups superimposed one upon the other, comprising all the strata from the inferior oolite to the coal and carboniferous limestone. the limited extension of the groups and . is owing to denudation, as these formations end abruptly, and have left outlying patches to attest the fact of their having originally covered a much wider area. in many instances, however, the entire absence of one or more formations of intervening periods between two groups, such as . and . in the same section, arises, not from the destruction of what once existed, but because no strata of an intermediate age were ever deposited on the inferior rock. they were not formed at that place, either because the region was dry land during the interval, or because it was part of a sea or lake to which no sediment was carried. in order, therefore, to establish a chronological succession of fossiliferous groups, a geologist must begin with a single section, in which several sets of strata lie one upon the other. he must then trace these formations, by attention to their mineral character and fossils, continuously, as far as possible, from the starting point. as often as he meets with new groups, he must ascertain by superposition their age relatively to those first examined, and thus learn how to intercalate them in a tabular arrangement of the whole. by this means the german, french, and english geologists have determined the succession of strata throughout a great part of europe, and have adopted pretty generally the following groups, almost all of which have their representatives in the british islands. _groups of fossiliferous strata observed in western europe, arranged in what is termed a descending series, or beginning with the newest._ (_see a more detailed tabular view_, pp. . .) . post-pliocene, including those of the recent, or human period. . newer pliocene, or pleistocene. } . older pliocene. } tertiary, supracretaceous[ -a], . miocene. } or cainozoic.[ -b] . eocene. } . chalk. } . greensand. } . wealden. } . upper oolite. } secondary, or mesozoic.[ -b] . middle oolite. } . lower oolite. } . lias. } . trias. } . permian. } . coal. } . old red sandstone, or devonian. } primary fossiliferous, . upper silurian. } or paleozoic.[ -b] . lower silurian. } . cambrian and older fossiliferous strata. } it is not pretended that the three principal sections in the above table, called primary, secondary, and tertiary, are of equivalent importance, or that the eighteen subordinate groups comprise monuments relating to equal portions of past time, or of the earth's history. but we can assert that they each relate to successive periods, during which certain animals and plants, for the most part peculiar to their respective eras, have flourished, and during which different kinds of sediment were deposited in the space now occupied by europe. if we were disposed, on palæontological grounds[ -c], to divide the entire fossiliferous series into a few groups less numerous than those in the above table, and more nearly co-ordinate in value than the sections called primary, secondary, and tertiary, we might, perhaps, adopt the six groups or periods given in the next table (p. .). at the same time, i may observe, that, in the present state of the science, when we have not yet compared the evidence derivable from all classes of fossils, not even those most generally distributed, such as shells, corals, and fish, such generalizations are premature, and can only be regarded as conjectural or provisional schemes for the founding of large natural groups. _fossiliferous strata of western europe divided into six groups._ . post pliocene and } from the post-pliocene to the tertiary } eocene inclusive. . cretaceous { from the maestricht chalk to the lower { greensand inclusive. . oolitic from the wealden to the lias inclusive. . triassic { including the keuper, muschelkalk, and { bunter sandstein of the germans. . permian, carboniferous, } including magnesian limestone (zechstein), and devonian } coal, mountain limestone, and } old red sandstone. . silurian and cambrian } from the upper silurian to the oldest } fossiliferous rocks inclusive. footnotes: [ -a] for tertiary, sir h. de la beche has used the term "supracretaceous," a name implying that the strata so called are superior in position to the chalk. [ -b] professor phillips has adopted these terms: cainozoic, from +kainos+, _cainos_, recent, and +zôon+, _zoon_, animal; mesozoic, from +mesos+, _mesos_, middle, &c.; paleozoic, from +palaios+, _palaios_, ancient, &c. [ -c] palæontology is the science which treats of fossil remains, both animal and vegetable. etym. +palaios+, _palaios_, ancient, +onta+, _onta_, beings, and +logos+, _logos_, a discourse. chapter x. classification of tertiary formations.--post-pliocene group. general principles of classification of tertiary strata--detached formations scattered over europe--strata of paris and london--more modern groups--peculiar difficulties in determining the chronology of tertiary formations--increasing proportion of living species of shells in strata of newer origin--terms eocene, miocene, and pliocene--post-pliocene strata--recent or human period--older post-pliocene formations of naples, uddevalla, and norway--ancient upraised delta of the mississippi--loess of the rhine. before describing the most modern of the sets of strata enumerated in the tables given at the end of the last chapter, it will be necessary to say something generally of the mode of classifying the formations called tertiary. the name of tertiary has been given to them, because they are all posterior in date to the rocks termed "secondary," of which the chalk constitutes the newest group. these tertiary strata were at first confounded, as before stated, p. ., with the superficial alluviums of europe; and it was long before their real extent and thickness, and the various ages to which they belong, were fully recognized. they were observed to occur in patches, some of freshwater, others of marine origin, their geographical area being usually small as compared to the secondary formations, and their position often suggesting the idea of their having been deposited in different bays, lakes, estuaries, or inland seas, after a large portion of the space now occupied by europe had already been converted into dry land. the first deposits of this class, of which the characters were accurately determined, were those occurring in the neighbourhood of paris, described in by mm. cuvier and brongniart. they were ascertained to consist of successive sets of strata, some of marine, others of freshwater origin, lying one upon the other. the fossil shells and corals were perceived to be almost all of unknown species, and to have in general a near affinity to those now inhabiting warmer seas. the bones and skeletons of land animals, some of them of large size, and belonging to more than forty distinct species, were examined by cuvier, and declared by him not to agree specifically and for the most part not even generically, with any hitherto observed in the living creation. strata were soon afterwards brought to light in the vicinity of london, and in hampshire, which, although dissimilar in mineral composition, were justly inferred by mr. t. webster to be of the same age as those of paris, because the greater number of the fossil shells were specifically identical. for the same reason rocks found on the gironde, in the south of france, and at certain points in the north of italy, were suspected to be of contemporaneous origin. a variety of deposits were afterwards found in other parts of europe, all reposing immediately on rocks as old or older than the chalk, and which exhibited certain general characters of resemblance in their organic remains to those previously observed near paris and london. an attempt was therefore made at first to refer the whole to one period; and when at length this seemed impracticable, it was contended that as in the parisian series there were many subordinate formations of considerable thickness which must have accumulated one after the other, during a great lapse of time, so the various patches of tertiary strata scattered over europe might correspond in age, some of them to the older, and others to the newer, subdivisions of the parisian series. this error, although most unavoidable on the part of those who made the first generalizations in this branch of geology, retarded seriously for some years the progress of classification. a more scrupulous attention to specific distinctions, aided by a careful regard to the relative position of the strata containing them, led at length to the conviction that there were formations both marine and freshwater of various ages, and all newer than the strata of the neighbourhood of paris and london. one of the first steps in this chronological reform was made in , by an english naturalist, mr. parkinson, who pointed out the fact that certain shelly strata, provincially termed "crag" in suffolk, lay decidedly over a deposit which was the continuation of the blue clay of london. at the same time he remarked that the fossil testacea in these newer beds were distinct from those of the blue clay, and that while some of them were of unknown species, others were identical with species now inhabiting the british seas. another important discovery was soon afterwards made by brocchi in italy, who investigated the argillaceous and sandy deposits replete with shells which form a low range of hills, flanking the apennines on both sides, from the plains of the po to calabria. these lower hills were called by him the subapennines, and were formed of strata of different ages, all newer than those of paris and london. another tertiary group occurring in the neighbourhood of bordeaux and dax, in the south of france, was examined by m. de basterot in , who described and figured several hundred species of shells, which differed for the most part both from the parisian series and those of the subapennine hills. it was soon, therefore, suspected that this fauna might belong to a period intermediate between that of the parisian and subapennine strata, and it was not long before the evidence of superposition was brought to bear in support of this opinion; for other strata, contemporaneous with those of bordeaux, were observed in one district (the valley of the loire), to overlie the parisian formation, and in another (in piedmont) to underlie the subapennine beds. the first example of these was pointed out in by m. desnoyers, who ascertained that the sand and marl of marine origin called faluns, near tours, in the basin of the loire, full of sea-shells and corals, rested upon a lacustrine formation, which constitutes the uppermost subdivision of the parisian group, extending continuously throughout a great table-land intervening between the basin of the seine and that of the loire. the other example occurs in italy, where strata, containing many fossils similar to those of bordeaux, were observed by bonelli and others in the environs of turin, subjacent to strata belonging to the subapennine group of brocchi. without pretending to give a complete sketch of the progress of discovery, i may refer to the facts above enumerated, as illustrating the course usually pursued by geologists when they attempt to found new chronological divisions. the method bears some analogy to that pursued by the naturalist in the construction of genera, when he selects a typical species, and then classes as congeners all other species of animals and plants which agree with this standard within certain limits. the genera a. and c. having been founded on these principles, a new species is afterwards met with, departing widely both from a. and c., but in many respects of an intermediate character. for this new type it becomes necessary to institute the new genus b., in which are included all species afterwards brought to light, which agree more nearly with b. than with the types of a. or c. in like manner a new formation is met with in geology, and the characters of its fossil fauna and flora investigated. from that moment it is considered as a record of a certain period of the earth's history, and a standard to which other deposits may be compared. if any are found containing the same or nearly the same organic remains, and occupying the same relative position, they are regarded in the light of contemporary annals. all such monuments are said to relate to one period, during which certain events occurred, such as the formation of particular rocks by aqueous or volcanic agency, or the continued existence and fossilization of certain tribes of animals and plants. when several of these periods have had their true places assigned to them in a chronological series, others are discovered which it becomes necessary to intercalate between those first known; and the difficulty of assigning clear lines of separation must unavoidably increase in proportion as chasms in the past history of the globe are filled up. every zoologist and botanist is aware that it is a comparatively easy task to establish genera in departments which have been enriched with only a small number of species, and where there is as yet no tendency in one set of characters to pass almost insensibly, by a multitude of connecting links, into another. they also know that the difficulty of classification augments, and that the artificial nature of their divisions becomes more apparent, in proportion to the increased number of objects brought to light. but in separating families and genera, they have no other alternative than to avail themselves of such breaks as still remain, or of every hiatus in the chain of animated beings which is not yet filled up. so in geology, we may be eventually compelled to resort to sections of time as arbitrary, and as purely conventional, as those which divide the history of human events into centuries. but in the present state of our knowledge, it is more convenient to use the interruptions which still occur in the regular sequence of geological monuments, as boundary lines between our principal groups or periods, even though the groups thus established are of very unequal value. the isolated position of distinct tertiary deposits in different parts of europe has been already alluded to. in addition to the difficulty presented by this want of continuity when we endeavour to settle the chronological relations of these deposits, another arises from the frequent dissimilarity in mineral character of strata of contemporaneous date, such, for example, as those of london and paris before mentioned. the identity or non-identity of species is also a criterion which often fails us. for this we might have been prepared, for we have already seen, that the mediterranean and red sea, although within miles of each other, on each side of the isthmus of suez, have each their peculiar fauna; and a marked difference is found in the four groups of testacea now living in the baltic, english channel, black sea, and mediterranean, although all these seas have many species in common. in like manner a considerable diversity in the fossils of different tertiary formations, which have been thrown down in distinct seas, estuaries, bays, and lakes, does not always imply a distinctness in the times when they were produced, but may have arisen from climate and conditions of physical geography wholly independent of time. on the other hand, it is now abundantly clear, as the result of geological investigation, that different sets of tertiary strata, immediately superimposed upon each other, contain distinct imbedded species of fossils, in consequence of fluctuations which have been going on in the animate creation, and by which in the course of ages one state of things in the organic world has been substituted for another wholly dissimilar. it has also been shown that in proportion as the age of a tertiary deposit is more modern, so is its fauna more analogous to that now in being in the neighbouring seas. it is this law of a nearer agreement of the fossil testacea with the species now living, which may often furnish us with a clue for the chronological arrangement of scattered deposits, where we cannot avail ourselves of any one of the three ordinary chronological tests; namely, superposition, mineral character, and the specific identity of the fossils. thus, for example, on the african border of the red sea, at the height of feet, and sometimes more, above its level, a white calcareous formation has been observed, containing several hundred species of shells differing from those found in the clay and volcanic tuff of the country round naples, and of the contiguous island of ischia. another deposit has been found at uddevalla, in sweden, in which the shells do not agree with those found near naples. but although in these three cases there may be scarcely a single shell common to the three different deposits, we do not hesitate to refer them all to one period (the post-pliocene), because of the very close agreement of the fossil species in every instance with those now living in the contiguous seas. to take another example, where the fossil fauna recedes a few steps farther back from our own times. we may compare, first, the beds of loam and clay bordering the clyde in scotland (called glacial by some geologists), secondly, others of fluvio-marine origin near norwich, and, lastly, a third set often rising to considerable heights in sicily, and we discover that in every case more than three-fourths of the shells agree with species still living, while the remainder are extinct. hence we may conclude that all these, greatly diversified as are their organic remains, belong to one and the same era, or to a period immediately antecedent to the post-pliocene, because there has been time in each of the areas alluded to for an equal or nearly equal amount of change in the marine testaceous fauna. contemporaneousness of origin is inferred in these cases, in spite of the most marked differences of mineral character or organic contents, from a similar degree of divergence in the shells from those now living in the adjoining seas. the advantage of such a test consists in supplying us with a common point of departure in all countries, however remote. but the farther we recede from the present times, and the smaller the relative number of recent as compared with extinct species in the tertiary deposits, the less confidence can we place in the exact value of such a test, especially when comparing the strata of very distant regions; for we cannot presume that the rate of former alterations in the animate world, or the continual going out and coming in of species, has been every where exactly equal in equal quantities of time. the form of the land and sea, and the climate, may have changed more in one region than in another; and consequently there may have been a more rapid destruction and renovation of species in one part of the globe than elsewhere. considerations of this kind should undoubtedly put us on our guard against relying too implicitly on the accuracy of this test; yet it can never fail to throw great light on the chronological relations of tertiary groups with each other, and with the post-pliocene period. we may derive a conviction of this truth not only from a study of geological monuments of all ages, but also by reflecting on the tendency which prevails in the present state of nature to a uniform rate of simultaneous fluctuation in the flora and fauna of the whole globe. the grounds of such a doctrine cannot be discussed here, and i have explained them at some length in the third book of the principles of geology, where the causes of the successive extinction of species are considered. it will be there seen that each local change in climate and physical geography is attended with the immediate increase of certain species, and the limitation of the range of others. a revolution thus effected is rarely, if ever, confined to a limited space, or to one geographical province of animals or plants, but affects several other surrounding and contiguous provinces. in each of these, moreover, analogous alterations of the stations and habitations of species are simultaneously in progress, reacting in the manner already alluded to on the first province. hence, long before the geography of any particular district can be essentially altered, the flora and fauna throughout the world will have been materially modified by countless disturbances in the mutual relation of the various members of the organic creation to each other. to assume that in one large area inhabited exclusively by a single assemblage of species any important revolution in physical geography can be brought about, while other areas remain stationary in regard to the position of land and sea, the height of mountains, and so forth, is a most improbable hypothesis, wholly opposed to what we know of the laws now governing the aqueous and igneous causes. on the other hand, even were this conceivable, the communication of heat and cold between different parts of the atmosphere and ocean is so free and rapid, that the temperature of certain zones cannot be materially raised or lowered without others being immediately affected; and the elevation or diminution in height of an important chain of mountains or the submergence of a wide tract of land would modify the climate even of the antipodes. it will be observed that in the foregoing allusions to organic remains, the testacea or the shell-bearing mollusca are selected as the most useful and convenient class for the purposes of general classification. in the first place, they are more universally distributed through strata of every age than any other organic bodies. those families of fossils which are of rare and casual occurrence are absolutely of no avail in establishing a chronological arrangement. if we have plants alone in one group of strata and the bones of mammalia in another, we can draw no conclusion respecting the affinity or discordance of the organic beings of the two epochs compared; and the same may be said if we have plants and vertebrated animals in one series and only shells in another. although corals are more abundant, in a fossil state, than plants, reptiles, or fish, they are still rare when contrasted with shells, especially in the european tertiary formations. the utility of the testacea is, moreover, enhanced by the circumstance that some forms are proper to the sea, others to the land, and others to freshwater. rivers scarcely ever fail to carry down into their deltas some land shells, together with species which are at once fluviatile and lacustrine. by this means we learn what terrestrial, freshwater, and marine species co-existed at particular eras of the past; and having thus identified strata formed in seas with others which originated contemporaneously in inland lakes, we are then enabled to advance a step farther, and show that certain quadrupeds or aquatic plants, found fossil in lacustrine formations, inhabited the globe at the same period when certain fish, reptiles, and zoophytes lived in the ocean. among other characters of the molluscous animals, which render them extremely valuable in settling chronological questions in geology, may be mentioned, first, the wide geographical range of many species; and, secondly, what is probably a consequence of the former, the great duration of species in this class, for they appear to have surpassed in longevity the greater number of the mammalia and fish. had each species inhabited a very limited space, it could never, when imbedded in strata, have enabled the geologist to identify deposits at distant points; or had they each lasted but for a brief period, they could have thrown no light on the connection of rocks placed far from each other in the chronological, or, as it is often termed, vertical series. many authors have divided the european tertiary strata into three groups--lower, middle, and upper; the lower comprising the oldest formations of paris and london before-mentioned; the middle those of bordeaux and touraine; and the upper all those newer than the middle group. when engaged in in preparing my work on the principles of geology, i conceived the idea of classing the whole series of tertiary strata in four groups, and endeavouring to find characters for each, expressive of their different degrees of affinity to the living fauna. with this view, i obtained information respecting the specific identity of many tertiary and recent shells from several italian naturalists, and among others from professors bonelli, guidotti, and costa. having in become acquainted with m. deshayes, of paris, already well known by his conchological works, i learnt from him that he had arrived, by independent researches, and by the study of a large collection of fossil and recent shells, at very similar views respecting the arrangement of tertiary formations. at my request he drew up, in a tabular form, lists of all the shells known to him to occur both in some tertiary formation and in a living state, for the express purpose of ascertaining the proportional number of fossil species identical with the recent which characterized successive groups; and this table, planned by us in common, was published by me in .[ -a] the number of tertiary fossil shells examined by m. deshayes was about ; and the recent species with which they had been compared about . the result then arrived at was, that in the lower tertiary strata, or those of london and paris, there were about - / per cent. of species identical with recent; in the middle tertiary of the loire and gironde about per cent.; and in the upper tertiary or subapennine beds, from to per cent. in formations still more modern, some of which i had particularly studied in sicily, where they attain a vast thickness and elevation above the sea, the number of species identical with those now living was believed to be from to per cent. for the sake of clearness and brevity, i proposed to give short technical names to these four groups, or the periods to which they respectively belonged. i called the first or oldest of them eocene, the second miocene, the third older pliocene, and the last or fourth newer pliocene. the first of the above terms, eocene, is derived from +êôs+, eos, _dawn_, and +kainos+, cainos, _recent_, because the fossil shells of this period contain an extremely small proportion of living species, which may be looked upon as indicating the dawn of the existing state of the testaceous fauna, no recent species having been detected in the older or secondary rocks. the term miocene (from +meion+, meion, _less_, and +kainos+, cainos, _recent_) is intended to express a minor proportion of recent species (of testacea), the term pliocene (from +pleion+, pleion, _more_, and +kainos+, cainos, _recent_) a comparative plurality of the same. it may assist the memory of students to remind them, that the _mi_ocene contain a _mi_nor proportion, and _pl_iocene a comparative _pl_urality of recent species; and that the greater number of recent species always implies the more modern origin of the strata. it has sometimes been objected to this nomenclature that certain species of infusoria found in the chalk are still existing, and, on the other hand, the miocene and older pliocene deposits often contain the remains of mammalia, reptiles, and fish, exclusively of extinct species. but the reader must bear in mind that the terms eocene, miocene, and pliocene were originally invented with reference purely to conchological data, and in that sense have always been and are still used by me. the distribution of the fossil species from which the results before mentioned were obtained in by m. deshayes was as follows:-- in the formations of the pliocene periods, older and newer in the miocene in the eocene ---- ---- since the year the progress of conchological science has been most rapid, and the number of living species obtained from different parts of the globe has been raised from about to more than , . new fossil species have also been added to our collections in great abundance; and at the same time a more copious supply of individuals both of fossil and recent species, some of which were previously very rare, have been procured, affording more ample data for determining the specific character. besides the reforms introduced in consequence of these new zoological facilities, other errors of a geological nature have been in many instances removed. post-pliocene formations. i have adopted the term post-pliocene for those strata which are sometimes called post-tertiary or modern, and which are characterized by having all the imbedded fossil shells identical with species now living, whereas even the newer pliocene, or newest of the tertiary deposits above alluded to, contain always some small proportion of shells of extinct species. these modern formations, thus defined, comprehend not only those strata which can be shown to have originated since the earth was inhabited by man, but also deposits of far greater extent and thickness, in which no signs of man or his works can be detected. in some of these, of a date long anterior to the times of history and tradition, the bones of extinct quadrupeds have been met with of species which probably never co-existed with the human race, as, for example, the mammoth, mastodon, megatherium, and others, and yet the shells are the same as those now living. that portion of the post-pliocene group which belongs to the human epoch, and which is sometimes called _recent_, forms a very unimportant feature in the geological structure of the earth's crust. i have shown, however, in "the principles," where the recent changes of the earth illustrative of geology are described at length, that the deposits accumulated at the bottom of lakes and seas within the last or years can neither be insignificant in volume or extent. they lie hidden, for the most part, from our sight; but we have opportunities of examining them at certain points where newly-gained land in the deltas of rivers has been cut through during floods, or where coral reefs are growing rapidly, or where the bed of a sea or lake has been heaved up by subterranean movements and laid dry. their age may be recognized either by our finding in them the bones of man in a fossil state, that is to say, imbedded in them by natural causes, or by their containing articles fabricated by the hands of man. thus at puzzuoli, near naples, marine strata are seen containing fragments of sculpture, pottery, and the remains of buildings, together with innumerable shells retaining in part their colour, and of the same species as those now inhabiting the bay of baiæ. the uppermost of these beds is about feet above the level of the sea. their emergence can be proved to have taken place since the beginning of the sixteenth century.[ -a] now here, as in almost every instance where any alterations of level have been going on in historical periods, it is found that rocks containing shells, all, or nearly all, of which still inhabit the neighbouring sea, may be traced for some distance into the interior, and often to a considerable elevation above the level of the sea. thus, in the country round naples, the post-pliocene strata, consisting of clay and horizontal beds of volcanic tuff, rise at certain points to the height of feet. although the marine shells are exclusively of living species, they are not accompanied like those on the coast at puzzuoli by any traces of man or his works. had any such been discovered, it would have afforded to the antiquary and geologist matter of great surprise, since it would have shown that man was an inhabitant of that part of the globe, while the materials composing the present hills and plains of campania were still in the progress of deposition at the bottom of the sea; whereas we know that for nearly years, or from the times of the earliest greek colonists, no material revolution in the physical geography of that part of italy has occurred. in ischia, a small island near naples, composed in like manner of marine and volcanic formations, dr. philippi collected in the stratified tuff and clay ninety-two species of shells of existing species. in the centre of ischia, the lofty hill called epomeo, or san nicola, is composed of greenish indurated tuff, of a prodigious thickness, interstratified in some parts with marl, and here and there with great beds of solid lava. visconti ascertained by trigonometrical measurement that this mountain was feet above the level of the sea. not far from its summit, at the height of about feet, as also near moropano, a village only feet lower, on the southern declivity of the mountain, i collected, in , many shells of species now inhabiting the neighbouring gulf. it is clear, therefore, that the great mass of epomeo was not only raised to its present height, but was also _formed_ beneath the waters, within the post-pliocene period. it is a fact, however, of no small interest, that the fossil shells from these modern tuffs of the volcanic region surrounding the bay of baiæ, although none of them extinct, indicate a slight want of correspondence between the ancient fauna and that now inhabiting the mediterranean. philippi informs us that when he and m. scacchi had collected ninety-nine species of them, he found that only one, _pecten medius_, now living in the red sea, was absent from the mediterranean. notwithstanding this, he adds, "the condition of the sea when the tufaceous beds were deposited must have been considerably different from its present state; for _tellina striata_ was then common, and is now rare; _lucina spinosa_ was both more abundant and grew to a larger size; _lucina fragilis_, now rare, and hardly measuring lines, then attained the enormous dimensions of lines, and was extremely abundant; and _ostrea lamellosa_, broc., no longer met with near naples, existed at that time, and attained a size so large that one lower valve has been known to measure inches lines in length, inches in breadth, - / inch in thickness, and weighed - / ounces."[ -a] there are other parts of europe where no volcanic action manifests itself at the surface, as at naples, whether by the eruption of lava or by earthquakes, and yet where the land and bed of the adjoining sea are undergoing upheaval. the motion is so gradual as to be insensible to the inhabitants, being only ascertainable by careful scientific measurements compared after long intervals. such an upward movement has been proved to be in progress in norway and sweden throughout an area about miles n. and s., and for an unknown distance e. and w., the amount of elevation always increasing as we proceed towards the north cape, where it may equal feet in a century. if we could assume that there had been an average rise of - / feet in each hundred years for the last fifty centuries, this would give an elevation of feet in that period. in other words, it would follow that the shores, and a considerable area of the former bed of the baltic and north sea, had been uplifted vertically to that amount, and converted into land in the course of the last years. accordingly, we find near stockholm, in sweden, horizontal beds of sand, loam, and marl containing the same peculiar assemblage of testacea which now live in the brackish waters of the baltic. mingled with these, at different depths, have been detected various works of art implying a rude state of civilization, and some vessels built before the introduction of iron, the whole marine formation having been upraised, so that the upper beds are now feet higher than the surface of the baltic. in the neighbourhood of these recent strata, both to the north-west and south of stockholm, other deposits similar in mineral composition occur, which ascend to greater heights, in which precisely the same assemblage of fossil shells is met with, but without any intermixture of human bones or fabricated articles. on the opposite or western coast of sweden, at uddevalla, post-pliocene strata, containing recent shells, not of that brackish water character peculiar to the baltic, but such as now live in the northern ocean, ascend to the height of feet; and beds of clay and sand of the same age attain elevations of and even feet in norway, where they have been usually described as "raised beaches." they are, however, thick deposits of submarine origin, spreading far and wide, and filling valleys in the granite and gneiss, just as the tertiary formations, in different parts of europe, cover or fill depressions in the older rocks. it is worthy of remark, that although the fossil fauna characterizing these upraised sands and clays consists exclusively of existing northern species of testacea, yet, according to lovén (an able living naturalist of norway), the species do not constitute such an assemblage as now inhabits corresponding latitudes in the german ocean. on the contrary, they decidedly represent a more arctic fauna.[ -a] in order to find the same species flourishing in equal abundance, or in many cases to find them at all, we must go northwards to higher latitudes than uddevalla in sweden, or even nearer the pole than central norway. judging by the uniformity of climate now prevailing from century to century, and the insensible rate of variation in the organic world in our own times, we may presume that an extremely lengthened period was required even for so slight a modification of the molluscous fauna, as that of which the evidence is here brought to light. on the other hand, we have every reason for inferring on independent grounds (namely, the rate of upheaval of land in modern times) that the antiquity of the deposits in question must be very great. for if we assume, as before suggested, that the mean rate of continuous vertical elevation has amounted to - / feet in a century (and this is probably a high average), it would require , years for the sea-coast to attain the height of feet, without making allowance for any pauses such as are now experienced in a large part of norway, or for any oscillations of level. in england, buried ships have been found in the ancient and now deserted channels of the rother in sussex, of the mersey in kent, and the thames near london. canoes and stone hatchets have been dug up, in almost all parts of the kingdom, from peat and shell-marl; but there is no evidence, as in sweden, italy, and many other parts of the world, of the bed of the sea, and the adjoining coast, having been uplifted bodily to considerable heights within the human period. recent strata have been traced along the coasts of peru and chili, inclosing shells in abundance, all agreeing specifically with those now swarming in the pacific. in one bed of this kind, in the island of san lorenzo, near lima, mr. darwin found, at the altitude of feet above the sea, pieces of cotton-thread, plaited rush, and the head of a stalk of indian corn, the whole of which had evidently been imbedded with the shells. at the same height on the neighbouring mainland, he found other signs corroborating the opinion that the ancient bed of the sea had there also been uplifted feet, since the region was first peopled by the peruvian race.[ -a] but similar shelly masses are also met with at much higher elevations, at innumerable points between the chilian and peruvian andes and the sea-coast, in which no human remains were ever, or in all probability ever will be, discovered. in the west indies, also, in the island of guadaloupe, a solid limestone occurs, at the level of the sea-beach, enveloping human skeletons. the stone is extremely hard, and chiefly composed of comminuted shell and coral, with here and there some entire corals and shells, of species now living in the adjacent ocean. with them are included arrow-heads, fragments of pottery, and other articles of human workmanship. a limestone with similar contents has been formed, and is still forming, in st. domingo. but there are also more ancient rocks in the west indian archipelago, as in cuba, near the havanna, and in other islands, in which are shells identical with those now living in corresponding latitudes; some well-preserved, others in the state of casts, all referable to the post-pliocene period. i have already described in the seventh chapter, p. ., what would be the effects of oscillations and changes of level in any region drained by a great river and its tributaries, supposing the area to be first depressed several hundred feet, and then re-elevated. i believe that such changes in the relative level of land and sea have actually occurred in the post-pliocene era in the hydrographical basin of the mississippi and in that of the rhine. the accumulation of fluviatile matter in a delta during a slow subsidence may raise the newly gained land superficially at the same rate at which its foundations sink, so that these may go down hundreds or thousands of feet perpendicularly, and yet the sea bordering the delta may always be excluded, the whole deposit continuing to be terrestrial or freshwater in character. this appears to have happened in the deltas both of the po and ganges, for recent artesian borings, penetrating to the depth of feet, have there shown that fluviatile strata, with shells of recent species, together with ancient surfaces of land supporting turf and forests, are depressed hundreds of feet below the sea level.[ -a] should these countries be once more slowly upraised, the rivers would carve out valleys through the horizontal and unconsolidated strata as they rose, sweeping away the greater portion of them, and leaving mere fragments in the shape of terraces skirting newly-formed alluvial plains, as monuments of the former levels at which the rivers ran. of this nature are "the bluffs," or river cliffs, now bounding the valley of the mississippi throughout a large portion of its course. thus let _a b_, fig. ., represent the alluvial plain of the mississippi, a plain which, at the point alluded to, is more than miles broad, and is truly a prolongation of the modern delta of that river. it is bounded by bluffs, the upper portions of which consist, both on the east and west side, of shelly loam, no. . rising from to feet above the level of the plain, and containing land and freshwater shells of the genera _helix_, _pupa_, _succinea_, and _lymnea_, of the same species as those now inhabiting the neighbouring forests and swamps. in the same loam also, no. ., are found the bones of the mastodon, elephant, megalonyx, and other extinct quadrupeds. [illustration: fig. . valley of the mississippi. . alluvium. . loess. . _f_. eocene. . cretaceous.] i have endeavoured to show that the deposits forming the delta and alluvial plain of the mississippi consist of sedimentary matter, extending over an area of , square miles, and known in some parts to be several hundred feet deep. although we cannot estimate correctly how many years it may have required for the river to bring down from the upper country so large a quantity of earthy matter--the data for such a computation being as yet incomplete--we may still approximate to a minimum of the time which such an operation must have taken, by ascertaining experimentally the annual discharge of water by the mississippi, and the mean annual amount of solid matter contained in its waters. the lowest estimate of the time required would lead us to assign a high antiquity, amounting to many tens of thousands of years to the existing delta, the origin of which is nevertheless an event of yesterday when contrasted with those terraces, _c_, and _d e_, fig. ., formed of the loam no. . above mentioned. these materials of the bluffs _a_ and _d_ were produced, the reader will observe, during the first part of that great oscillation of level which depressed to a depth of feet a larger area than the modern delta and plain of the mississippi, and then restored the region to its former position.[ -a] _loess of the valley of the rhine._--a similar succession of geographical changes, attended by the production of a fluviatile formation, singularly resembling that which bounds the great plain of the mississippi, seems to have occurred in the hydrographical basin of the rhine, since the time when that basin had already acquired its present outline of hill and valley. i allude to the deposit provincially termed _loess_ in part of germany, or _lehm_ in alsace, filled with land and freshwater shells of existing species. it is a finely comminuted sand or pulverulent loam of a yellowish grey colour, consisting chiefly of argillaceous matter combined with a sixth part of carbonate of lime, and a sixth of quartzose and micaceous sand. it often contains calcareous sandy concretions or nodules, rarely exceeding the size of a man's head. its entire thickness amounts, in some places, to between and feet; yet there are often no signs of stratification in the mass, except here and there at the bottom, where there is occasionally a slight intermixture of drifted materials derived from subjacent rocks. unsolidified as it is, and of so perishable a nature, that every streamlet flowing over it cuts out for itself a deep gully, it usually terminates in a vertical cliff, from the surface of which land shells are seen here and there to project in relief. in all these features it presents a precise counterpart to the loess of the mississippi. it is so homogeneous as generally to exhibit no signs of stratification, owing, probably, to its materials having been derived from a common source, and having been accumulated by a uniform action. yet it displays in some few places decided marks of successive deposition, where coarser and finer materials alternate, especially near the bottom. calcareous concretions, also enclosing land-shells, are sometimes arranged in horizontal layers. it is a remarkable deposit, from its position, wide extent, and thickness, its homogeneous mineral composition, and freshwater origin. its distribution clearly shows that after the great valley of the rhine, from schaffhausen to bonn, had acquired its present form, having its bottom strewed over with coarse gravel, a period arrived when it became filled up from side to side with fine mud, which was also thrown down in the valleys of the principal tributaries of the rhine. thus, for example, it may be traced far into würtemberg, up the valley of the neckar, and from frankfort, up the valley of the main, to above dettelbach. i have also seen it spreading over the country of mayence, eppelsheim, and worms, on the left bank of the rhine, and on the opposite side on the table-land above the bergstrasse, between wiesloch and bruchsal, where it attains a thickness of feet. near strasburg, large masses of it appear at the foot of the vosges on the left bank, and at the base of the mountains of the black forest on the right bank. the kaiserstuhl, a volcanic mountain which stands in the middle of the plain of the rhine near freiburg, has been covered almost everywhere with this loam, as have the extinct volcanos between coblentz and bonn. near andernach, in the kirchweg, the loess containing the usual shells alternates with volcanic matter; and over the whole are strewed layers of pumice, lapilli, and volcanic sand, from to feet thick, very much resembling the ejections under which pompeii lies buried. there is no passage at this upper junction from the loess into the pumiceous superstratum; and this last follows the slope of the hill, just as it would have done had it fallen in showers from the air on a declivity partly formed of loess. but, in general, the loess overlies all the volcanic products, even those between neuwied and bonn, which have the most modern aspect; and it has filled up in part the crater of the roderberg, an extinct volcano near bonn. in a well was sunk at the bottom of this crater, through feet of loess, in part of which were the usual calcareous concretions. the interstratification above alluded to, of loess with layers of pumice and volcanic ashes, has led to the opinion that both during and since its deposition some of the last volcanic eruptions of the lower eifel have taken place. should such a conclusion be adopted, we should be called upon to assign a very modern date to these eruptions. this curious point, therefore, deserves to be reconsidered; since it may possibly have happened that the waters of the rhine, swollen by the melting of snow and ice, and flowing at a great height through a valley choked up with loess, may have swept away the loose superficial scoriæ and pumice of the eifel volcanos, and spread them out occasionally over the yellow loam. sometimes, also, the melting of snow on the slope of small volcanic cones may have given rise to local floods, capable of sweeping down light pumice into the adjacent low grounds. the first idea which has occurred to most geologists, after examining the loess between mayence and basle, is to imagine that a great lake once extended throughout the valley of the rhine between those two places. such a lake may have sent off large branches up the course of the main, neckar, and other tributary valleys, in all of which large patches of loess are now seen. the barrier of the lake might be placed somewhere in the narrow and picturesque gorge of the rhine between bingen and bonn. but this theory fails altogether to explain the phenomena; when we discover that that gorge itself has once been filled with loess, which must have been tranquilly deposited in it, as also in the lateral valley of the lahn, communicating with the gorge. the loess has also overspread the high adjoining platform near the village of plaidt above andernach. nay, on proceeding farther down to the north, we discover that the hills which skirt the great valley between bonn and cologne have loess on their flanks, which also covers here and there the gravel of the plain as far as cologne, and the nearest rising grounds. besides these objections to the lake theory, the loess is met with near basle, capping hills more than feet above the sea; so that a barrier of land capable of separating the supposed lake from the ocean would require to be, at least, as high as the mountains called the siebengebirge, near bonn, the loftiest summit of which, the oehlberg, is feet above the rhine and feet above the sea. it would be necessary, moreover, to place this lofty barrier somewhere below cologne, or precisely where the level of the land is now lowest. instead, therefore, of supposing one continuous lake of sufficient extent and depth to allow of the simultaneous accumulation of the loess, at various heights, throughout the whole area where it now occurs, i formerly suggested that, subsequently to the period when the countries now drained by the rhine and its tributaries had nearly acquired their actual form and geographical features, they were again depressed gradually by a movement like that now in progress on the west coast of greenland.[ -a] in proportion as the whole district was lowered, the general fall of the waters between the alps and the ocean was lessened; and both the main and lateral valleys, becoming more subject to river inundations, were partially filled up with fluviatile silt, containing land and freshwater shells. when a thickness of many hundred feet of loess had been thrown down slowly by this operation, the whole region was once more upheaved gradually. during this upward movement most of the fine loam would be carried off by the denuding power of rains and rivers; and thus the original valleys might have been re-excavated, and the country almost restored to its pristine state, with the exception of some masses and patches of loess such as still remain, and which, by their frequency and remarkable homogeneousness of composition and fossils, attest the ancient continuity and common origin of the whole. by imagining these oscillations of level, we dispense with the necessity of erecting and afterwards removing a mountain barrier sufficiently high to exclude the ocean from the valley of the rhine during the period of the accumulation of the loess. the proportion of land shells of the genera _helix_, _pupa_, and _bulimus_, is very large in the loess; but in many places aquatic species of the genera _lymnea_, _paludina_, and _planorbis_ are also found. these may have been carried away during floods from shallow pools and marshes bordering the river; and the great extent of marshy ground caused by the wide overflowings of rivers above supposed would favour the multiplication of amphibious mollusks, such as the _succinea_ (fig. .), which is almost everywhere characteristic of this formation, and is sometimes accompanied, as near bonn, by another species, _s. amphibia_ (fig. . p. .). among other abundant fossils are _helix plebeium_ and _pupa muscorum_. (see figures.) both the terrestrial and aquatic shells preserved in the loess are of most fragile and delicate structure, and yet they are almost invariably perfect and uninjured. they must have been broken to pieces had they been swept along by a violent inundation. even the colour of some of the land shells, as that of _helix nemoralis_, is occasionally preserved. [illustration: fig. . _succinea elongata._] [illustration: fig. . _pupa muscorum._] [illustration: fig. . _helix plebeium._] bones of vertebrated animals are rare in the loess, but those of the mammoth, horse, and some other quadrupeds have been met with. at the village of binningen, and the hills called bruderholz, near basle, i found the vertebræ of fish, together with the usual shells. these vertebræ, according to m. agassiz, belong decidedly to the shark family, perhaps to the genus _lamna_. in explanation of their occurrence among land and freshwater shells, it may be stated that certain fish of this family ascend the senegal, amazon, and other great rivers, to the distance of several hundred miles from the ocean.[ -a] at cannstadt, near stuttgart, in a valley also belonging to the hydrographical basin of the rhine, i have seen the loess pass downwards into beds of calcareous tuff and travertin. several valleys in northern germany, as that of the ilm at weimar, and that of the tonna, north of gotha, exhibit similar masses of modern limestone filled with recent shells of the genera _planorbis_, _lymnea_, _paludina_, &c., from to feet thick, with a bed of loess much resembling that of the rhine, occasionally incumbent on them. in these modern limestones used for building, the bones of _elephas primigenius_, _rhinoceros tichorinus_, _ursus spelæus_, _hyæna spelæa_, with the horse, ox, deer, and other quadrupeds, occur; and in mr. h. credner and i obtained in a quarry at tonna, at the depth of feet, inclosed in the calcareous rock and surrounded with dicotyledonous leaves and petrified leaves, four eggs of a snake of the size of the largest european coluber, which, with three others, had been found lying in a series, or string. they are, i believe, the first reptilian remains which have been met with in strata of this age. the agreement of the shells in these cases with recent european species enables us to refer to a very modern period the filling up and re-excavation of the valleys; an operation which doubtless consumed a long period of time, since which the mammiferous fauna has undergone a considerable change. footnotes: [ -a] see princ. of geol. vol. iii. st ed. [ -a] see principles, index, "serapis." [ -a] geol. quart. journ. vol. ii. memoirs, p. . [ -a] quart. geol. journ. mems. p. . [ -a] journal, p. . [ -a] see principles, th ed. pp. - . [ -a] lyell's second visit to the united states, vol. ii. chap. xxxiv. [ -a] princ. of geol. d edition, , vol. iii. p. . [ -a] proceedings geol. soc. no. . p. . chapter xi. newer pliocene period.--boulder formation. drift of scandinavia, northern germany, and russia--its northern origin--not all of the same age--fundamental rocks polished, grooved, and scratched--action of glaciers and icebergs--fossil shells of glacial period--drift of eastern norfolk--associated freshwater deposit--bent and folded strata lying on undisturbed beds--shells on moel tryfane--ancient glaciers of north wales--irish drift. among the different kinds of alluvium described in the seventh chapter, mention was made of the boulder formation in the north of europe, the peculiar characters of which may now be considered, as it belongs in part to the post-pliocene, and partly to the newer pliocene, period. i shall first allude briefly to that portion of it which extends from finland and the scandinavian mountains to the north of russia, and the low countries bordering the baltic, and which has been traced southwards as far as the eastern coast of england. this formation consists of mud, sand, and clay, sometimes stratified, but often wholly devoid of stratification, for a depth of more than a hundred feet. to this unstratified form of the deposit, the name of _till_ has been applied in scotland. it generally contains numerous fragments of rocks, some angular and others rounded, which have been derived from formations of all ages, both fossiliferous, volcanic, and hypogene, and which have often been brought from great distances. some of the travelled blocks are of enormous size, several feet or yards in diameter; their average dimensions increasing as we advance northwards. the till is almost everywhere devoid of organic remains, unless where these have been washed into it from older formations; so that it is chiefly from relative position that we must hope to derive a knowledge of its age. although a large proportion of the boulder deposit, or "northern drift," as it has sometimes been called, is made up of fragments brought from a distance, and which have sometimes travelled many hundred miles, the bulk of the mass in each locality consists of the ruins of subjacent or neighbouring rocks; so that it is red in a region of red sandstone, white in a chalk country, and grey or black in a district of coal and coal-shale. the fundamental rock on which the boulder formation reposes, if it consist of granite, gneiss, marble, or other hard stone capable of permanently retaining any superficial markings which may have been imprinted upon it, is smoothed or polished, and usually exhibits parallel striæ and furrows having a determinate direction. this direction, both in europe and north america, is evidently connected with the course taken by the erratic blocks in the same district being north or south, or or degrees to the east or west of north, according as the large angular and rounded stones have travelled. these stones themselves also are often furrowed and scratched on more than one side. [illustration: fig. . limestone polished, furrowed, and scratched by the glacier of rosenlaui, in switzerland. (agassiz.) _a a._ white streaks or scratches, caused by small grains of flint frozen into the ice. _b b._ furrows.] in explanation of such phenomena i may refer the student to what was said of the action of glaciers and icebergs in the principles of geology.[ -a] it is ascertained that hard stones, frozen into a moving mass of ice, and pushed along under the pressure of that mass, scoop out long rectilinear furrows or grooves parallel to each other on the subjacent solid rock. (see fig. .) smaller scratches and striæ are made on the polished surface by crystals or projecting edges of the hardest minerals, just as a diamond cuts glass. the recent polishing and striation of limestone by coast-ice carrying boulders even as far south as the coast of denmark, has been observed by dr. forchhammer, and helps us to conceive how large icebergs, running aground on the bed of the sea, may produce similar furrows on a grander scale. an account was given so long ago as the year , by scoresby, of icebergs seen by him drifting along in latitudes ° and ° n., which rose above the surface from to feet, and measured from a few yards to a mile in circumference. many of them were loaded with beds of earth and rock, of such thickness that the weight was conjectured to be from , to , tons.[ -b] a similar transportation of rocks is known to be in progress in the southern hemisphere, where boulders included in ice are far more frequent than in the north. one of these icebergs was encountered in , in mid-ocean, in the antarctic regions, many hundred miles from any known land, sailing northwards, with a large erratic block firmly frozen into it. in order to understand in what manner long and straight grooves may be cut by such agency, we must remember that these floating islands of ice have a singular steadiness of motion, in consequence of the larger portion of their bulk being sunk deep under water, so that they are not perceptibly moved by the winds and waves even in the strongest gales. many had supposed that the magnitude commonly attributed to icebergs by unscientific navigators was exaggerated, but now it appears that the popular estimate of their dimensions has rather fallen within than beyond the truth. many of them, carefully measured by the officers of the french exploring expedition of the astrolabe, were between and feet high above water, and from to miles in length. captain d'urville ascertained one of them which he saw floating in the southern ocean to be miles long and feet high, with walls perfectly vertical. the submerged portions of such islands must, according to the weight of ice relatively to sea-water, be from six to eight times more considerable than the part which is visible, so that the mechanical power they might exert when fairly set in motion must be prodigious.[ -a] glaciers formed in mountainous regions become laden with mud and stones, and if they melt away at their lower extremity before they reach the sea, they leave wherever they terminate a confused heap of unstratified rubbish, called "a moraine," composed of mud and pieces of all the rocks with which they were loaded. we may expect, therefore, to find a formation of the same kind, resulting from the liquefaction of icebergs, in tranquil water. but, should the action of a current intervene at certain points or at certain seasons, then the materials will be sorted as they fall, and arranged in layers according to their relative weight and size. hence there will be passages from _till_, as it is called in scotland, to stratified clay, gravel, and sand, and intercalations of one in the other. i have yet to mention another appearance connected with the boulder formation, which has justly attracted much attention in norway and other parts of europe. abrupt pinnacles and outstanding ridges of rock are often observed to be polished and furrowed on the north, or "strike" side as it is called, or on the side facing the region from which the erratics have come; while, on the other side, which is usually steeper and often perpendicular, called the "lee-side," such superficial markings are wanting. there is usually a collection on this lee-side of boulders and gravel, or of large angular fragments. in explanation we may suppose that the north side was exposed, when still submerged, to the action of icebergs, and afterwards, when the land was upheaved, of coast-ice, which ran aground upon shoals, or was _packed_ on the beach; so that there would be great wear and tear on the seaward slope, while, on the other, gravel and boulders might be heaped up in a sheltered position. _northern origin of erratics._--that the erratics of northern europe have been carried southward cannot be doubted; those of granite, for example, scattered over large districts of russia and poland, agree precisely in character with rocks of the mountains of lapland and finland; while the masses of gneiss, syenite, porphyry, and trap, strewed over the low sandy countries of pomerania, holstein, and denmark, are identical in mineral characters with the mountains of norway and sweden. it is found to be a general rule in russia, that the smaller blocks are carried to greater distances from their point of departure than the larger; the distance being sometimes and even miles from the nearest rocks from which they were broken off; the direction having been from n.w. to s.e., or from the scandinavian mountains over the seas and low lands to the south-east. that its accumulation throughout this area took place in part during the post-pliocene period is proved by its superposition at several points to strata containing recent shells. thus, for example, in european russia, mm. murchison and de verneuil found in , that the flat country between st. petersburg and archangel, for a distance of miles, consisted of horizontal strata, full of shells similar to those now inhabiting the arctic sea, on which rested the boulder formation, containing large erratics. in sweden, in the immediate neighbourhood of upsala, i observed, in , a ridge of stratified sand and gravel, in the midst of which is a layer of marl, evidently formed originally at the bottom of the baltic, by the slow growth of the mussel, cockle, and other marine shells, intermixed with some of freshwater species. the marine shells are all of dwarfish size, like those now inhabiting the brackish waters of the baltic; and the marl, in which myriads of them are imbedded, is now raised more than feet above the level of the gulf of bothnia. upon the top of this ridge repose several huge erratics, consisting of gneiss for the most part unrounded, from to feet in diameter, and which must have been brought into their present position since the time when the neighbouring gulf was already characterized by its peculiar fauna.[ -a] here, therefore, we have proof that the transport of erratics continued to take place, not merely when the sea was inhabited by the existing testacea, but when the north of europe had already assumed that remarkable feature of its physical geography, which separates the baltic from the north sea, and causes the gulf of bothnia to have only one fourth of the saltness belonging to the ocean. in denmark, also, recent shells have been found in stratified beds, closely associated with the boulder clay. it was stated that in russia the erratics diminished generally in size in proportion as they are traced farther from their source. the same observation holds true in regard to the average bulk of the scandinavian boulders, when we pursue them southwards, from the south of norway and sweden through denmark and westphalia. this phenomenon is in perfect harmony with the theory of ice-islands floating in a sea of variable depth; for the heavier erratics require icebergs of a larger size to buoy them up; and, even when there are no stones frozen in, more than seven eighths, and often nine tenths, of a mass of drift ice is under water. the greater, therefore, the volume of the iceberg, the sooner would it impinge on some shallower part of the sea; while the smaller and lighter floes, laden with finer mud and gravel, may pass freely over the same banks, and be carried to much greater distances. in those places, also, where in the course of centuries blocks have been carried southwards by coast-ice, having been often stranded and again set afloat in the direction of a prevailing current, the blocks will be worn and diminish in size the farther they travel from their point of departure. the "northern drift" of the most southern latitudes is usually of the highest antiquity. in scotland it rests immediately on the older rocks, and is covered by stratified sand and clay, usually devoid of fossils, but in which, at certain points near the east and west coast, as, for example, in the estuaries of the tay and clyde, marine shells have been discovered. the same shells have also been met with in the north, at wick in caithness, and on the shores of the moray frith. the principal deposit on the clyde occurs at the height of about feet, but a few shells have been traced in it as high as feet above the sea. although a proportion of between or in of the imbedded shells are of recent species, the remainder are unknown; and even many which are recent now inhabit more northern seas, where we may, perhaps, hereafter find living representatives of some of the unknown fossils. the distance to which erratic blocks have been carried southwards in scotland, and the course they have taken, which is often wholly independent of the present position of hill and valley, favours the idea that ice-rafts rather than glaciers were in general the transporting agents. the grampians in forfarshire and in perthshire are from to feet high. to the southward lies the broad and deep valley of strathmore, and to the south of this again rise the sidlaw hills[ -a] to the height of feet and upwards. on the highest summits of this chain, formed of sandstone and shale, and at various elevations, are found huge angular fragments of mica schist, some and others feet in diameter, which have been conveyed for a distance of at least miles from the nearest grampian rocks from which they could have been detached. others have been left strewed over the bottom of the large intervening vale of strathmore. still farther south on the pentland hills, at the height of feet above the sea, mr. maclaren has observed a fragment of mica-schist weighing from to tons, the nearest mountain composed of this formation being miles distant.[ -b] the testaceous fauna of the boulder period, in scotland, england, and ireland, has been shown by prof. e. forbes to contain a much smaller number of species than that now belonging to the british seas, and to have been also much less rich in species than the older pliocene fauna of the crag which preceded it. yet the species are nearly all of them now living either in the british or more northern seas, the shells of more arctic latitudes being the most abundant and the most wide spread throughout the entire area of the drift from north to south. this extensive range of the fossils can by no means be explained by imagining the mollusca of the drift to have been inhabitants of a deep sea, where a more uniform temperature prevailed. on the contrary, many species were littoral, and others belonged to a shallow sea, not above feet deep, and very few of them lived, according to prof. e. forbes, at greater depths than feet. from what was before stated it will appear that the boulder formation displays almost everywhere, in its mineral ingredients, a strange heterogeneous mixture of the ruins of adjacent lands, with stones both angular and rounded, which have come from points often very remote. thus we find it in our eastern counties, as in norfolk, suffolk, cambridge, huntingdon, bedford, hertford, essex, and middlesex, containing stones from the silurian and carboniferous strata, and from the lias, oolite, and chalk, all with their peculiar fossils, together with trap, syenite, mica-schist, granite, and other crystalline rocks. a fine example of this singular mixture extends to the very suburbs of london, being seen on the summit of muswell hill, highgate. but south of london the northern drift is wanting, as, for example, in the wealds of surrey, kent, and sussex. _norfolk drift._--the drift can nowhere be studied more advantageously in england than in the cliffs of the norfolk coast between happisburgh and cromer. vertical sections, having an ordinary height of from to feet, are there exposed to view for a distance of about miles. the name of diluvium was formerly given to it by those who supposed it to have been produced by the violent action of a sudden and transient deluge, but the term drift has been substituted by those who reject this hypothesis. here, as elsewhere, it consists for the most part of clay, loam, and sand, in part stratified, in part devoid of stratification. pebbles, together with some large boulders of granite, porphyry, greenstone, lias, chalk, and other transported rocks, are interspersed, especially through the till. that some of the granitic and other fragments came from scandinavia i have no doubt, after having myself traced the course of the continuous stream of blocks from norway and sweden to denmark, and across the elbe, through westphalia, to the borders of holland. we need not be surprised to find them reappear on our eastern coast, between the tweed and the thames, regions not half so remote from parts of norway as are many russian erratics from the sources whence they came. white chalk rubble, unmixed with foreign matter, and even huge fragments of solid chalk, also occur in many localities in these norfolk cliffs. no fossils have been detected in this drift, which can positively be referred to the era of its accumulation; but at some points it overlies a freshwater formation containing recent shells, and at others it is blended with the same in such a manner as to force us to conclude that both were contemporaneously deposited. [illustration: fig. . the shaded portion consists of freshwater beds. intercalation of freshwater beds and of boulder clay and sand at mundesley.] this interstratification is expressed in the annexed figure, the dark mass indicating the position of the freshwater beds, which contain much vegetable matter, and are divided into thin layers. the imbedded shells belong to the genera _planorbis_, _lymnea_, _paludina_, _unio_, _cyclas_, and others, all of british species, except a minute _paludina_ now inhabiting france. (see fig. .) [illustration: fig. . _paludina marginata_, michaud. (_p. minuta_, strickland.) the middle figure is of the natural size.] the _cyclas_ (fig. .) is merely a remarkable variety of the common english species. the scales and teeth of fish of the genera pike, perch, roach, and others, accompany these shells; but the species are not considered by m. agassiz to be identical with known british or european kinds. [illustration: fig. . _cyclas_ (_pisidium_) _amnica_, var.? the two middle figures are of the natural size.] the series of formations in the cliffs of eastern norfolk, now under consideration, beginning with the lowest, is as follows:--first, chalk; secondly, patches of a marine tertiary formation, called the norwich crag, hereafter to be described; thirdly, the freshwater beds already mentioned; and lastly, the drift. immediately above the chalk, or crag, when that is present, is found here and there a buried forest, or a stratum in which the stools and roots of trees stand in their natural position, the trunks having been broken short off and imbedded with their branches and leaves. it is very remarkable that the strata of the overlying boulder formation have often undergone great derangement at points where the subjacent forest bed and chalk remain undisturbed. there are also cases where the upper portion of the boulder deposit has been greatly deranged, while the lower beds of the same have continued horizontal. thus the annexed section (fig. .) represents a cliff about feet high, at the bottom of which is _till_, or unstratified clay, containing boulders, having an even horizontal surface, on which repose conformably beds of laminated clay and sand about feet thick, which, in their turn, are succeeded by vertical, bent, and contorted layers of sand and loam feet thick, the whole being covered by flint gravel. now the curves of the variously coloured beds of loose sand, loam, and pebbles are so complicated that not only may we sometimes find portions of them which maintain their verticality to a height of or feet, but they have also been folded upon themselves in such a manner that continuous layers might be thrice pierced in one perpendicular boring. [illustration: fig. . cliff feet high between bacton gap and mundesley.] [illustration: fig. . folding of the strata between east and west runton.] [illustration: fig. . section of concentric beds west of cromer. . blue clay. . white sand. . yellow sand. . striped loam and clay. . laminated blue clay.] at some points there is an apparent folding of the beds round a central nucleus, as at _a_, fig. ., where the strata seem bent round a small mass of chalk; or, as in fig. ., where the blue clay, no. ., is in the centre; and where the other strata, , , , , are coiled round it; the entire mass being feet in perpendicular height. this appearance of concentric arrangement around a nucleus is, nevertheless, delusive, being produced by the intersection of beds bent into a convex shape; and that which seems the nucleus being, in fact, the innermost bed of the series, which has become partially visible by the removal of the protuberant portions of the outer layers. to the north of cromer are other fine illustrations of contorted drift reposing on a floor of chalk horizontally stratified and having a level surface. these phenomena, in themselves sufficiently difficult of explanation, are rendered still more anomalous by the occasional inclosure in the drift of huge fragments of chalk many yards in diameter. one striking instance occurs west of sherringham, where an enormous pinnacle of chalk, between and feet in height, is flanked on both sides by vertical layers of loam, clay, and gravel. (fig. .) [illustration: fig. . included pinnacle of chalk at old hythe point, west of sherringham. _d._ chalk with regular layers of chalk flints. _c._ layer called "the pan," of loose chalk, flints, and marine shells of recent species, cemented by oxide of iron.] this chalky fragment is only one of many detached masses which have been included in the drift, and forced along with it into their present position. the level surface of the chalk _in situ_ (_d_) may be traced for miles along the coast, where it has escaped the violent movements to which the incumbent drift has been exposed.[ -a] we are called upon, then, to explain how any force can have been exerted against the upper masses, so as to produce movements in which the subjacent strata have not participated. it may be answered that, if we conceive the _till_ and its boulders to have been drifted to their present place by ice, the lateral pressure may have been supplied by the stranding of ice-islands. we learn, from the observations of messrs. dease and simpson in the polar regions, that such islands, when they run aground, push before them large mounds of shingle and sand. it is therefore probable that they often cause great alterations in the arrangement of pliant and incoherent strata forming the upper part of shoals or submerged banks, the inferior portions of the same remaining unmoved. or many of the complicated curvatures of these layers of loose sand and gravel may have been due to another cause, the melting on the spot of icebergs and coast ice in which successive deposits of pebbles, sand, ice, snow, and mud, together with huge masses of rock fallen from cliffs, may have become interstratified. ice-islands so constituted often capsize when afloat, and gravel once horizontal may have assumed, before the associated ice was melted, an inclined or vertical position. the packing of ice forced up on a coast may lead to similar derangement in a frozen conglomerate of sand or shingle, and, as mr. trimmer has suggested[ -a], alternate layers of earthy matter may have sunk down slowly during the liquefaction of the intercalated ice, so as to assume the most fantastic and anomalous positions, while the aqueous strata below, and those afterwards thrown down above, may be perfectly horizontal. a buried forest has been adverted to as underlying the drift on the coast of norfolk. at the time when the trees grew there must have been dry land over a large area, which was afterwards submerged, so as to allow a mass of stratified and unstratified drift, feet and more in thickness, to be superimposed. the undermining of the cliffs by the sea in modern times has enabled us to demonstrate, beyond all doubt, the fact of this superposition, and that the forest was not formed along the present coast-line. its situation implies a subsidence of several hundred feet since the commencement of the drift period, after which there must have been an upheaval of the same ground; for the forest bed of norfolk is now again so high as to be exposed to view at many points at low water; and this same upward movement may explain why the _till_, which is conceived to have been of submarine origin, is now met with far inland, and on the summit of hills. the boulder formation of the west of england, observed in lancashire, cheshire, shropshire, staffordshire, and worcestershire, contains in some places marine shells of recent species, rising to various heights, from to feet above the sea. the erratics have come partly from the mountains of cumberland, and partly from those of scotland. but it is on the mountains of north wales that the "northern drift," with its characteristic marine fossils, reaches its greatest altitude. on moel tryfane, near the menai straits, mr. trimmer met with shells of the species commonly found in the drift at the height of feet above the level of the sea. it is remarkable that in the same neighbourhood where there is evidence of so great a submergence of the land during part of the glacial period, we have also the most decisive proofs yet discovered in the british isles of subaerial glaciers. dr. buckland published in his reasons for believing that the snowdonian mountains in caernarvonshire were formerly covered with glaciers, which radiated from the central heights through the seven principal valleys of that chain, where striæ and flutings are seen on the polished rocks directed towards as many different points of the compass. he also described the "moraines" of the ancient glaciers, and the rounded "bosses" or small flattened domes of polished rock, such as the action of moving glaciers is known to produce in switzerland, when gravel, sand, and boulders, underlying the ice, are forced along over a foundation of hard stone. mr. darwin, and subsequently prof. ramsay, have confirmed dr. buckland's views in regard to these welsh glaciers. nor indeed was it to be expected that geologists should discover proofs of icebergs having abounded in the area now occupied by the british isles in the pleistocene period without sometimes meeting with the signs of contemporaneous glaciers which covered hills even of moderate elevation between the th and th degrees of latitude. in ireland the "drift" exhibits the same general characters and fossil remains as in scotland and england; but in the southern part of that island, prof. e. forbes and capt. james found in it some shells which show that the glacial sea communicated with one inhabited by a more southern fauna. among other species in the south, they mention at wexford and elsewhere the occurrence of _nucula cobboldiæ_ (see fig. . p. .) and _turritella incrassata_ (a crag fossil); also a southern form of _fusus_, and a _mitra_ allied to a spanish species.[ -a] footnotes: [ -a] chap. xvi. and the references there given. [ -b] voyage in , p. . [ -a] t. l. hayes, boston journ. nat. hist. . [ -a] see paper by the author, phil. trans. , p. . [ -a] see above, section, p. . [ -b] geol. of fife, &c. p. . [ -a] for a full account of the drift of east norfolk, see a paper by the author, phil. mag. no. . may, . [ -a] quart. journ. geol. soc. vol. vii. p. . [ -a] forbes, memoirs of geol. survey of great britain, vol. i. p. . chapter xii. boulder formation--_continued_. difficulty of interpreting the phenomena of drift before the glacial hypothesis was adopted--effects of intense cold in augmenting the quantity of alluvium--analogy of erratics and scored rocks in north america and europe--bayfield on shells in drift of canada--great subsidence and re-elevation of land from the sea, required to account for glacial appearances--why organic remains so rare in northern drift--mastodon giganteus in united states--many shells and some quadrupeds survived the glacial cold--alps an independent centre of dispersion of erratics--alpine blocks on the jura--whether transported by glaciers or floating ice--recent transportation of erratics from the andes to chiloe--meteorite in asiatic drift. it will appear from what was said in the last chapter of the marine shells characterizing the boulder formation, that nine-tenths or more of them belong to species still living. the superficial position of "the drift" is in perfect accordance with its imbedded organic remains, leading us to refer its origin to a modern period. if, then, we encounter so much difficulty in the interpretation of monuments relating to times so near our own--if in spite of their recent date they are involved in so much obscurity--the student may ask, not without reasonable alarm, how we can hope to decipher the records of remote ages. to remove from the mind as far as possible this natural feeling of discouragement, i shall endeavour in this chapter to prove that what seems most strikingly anomalous, in the "erratic formation," as some call it, is really the result of that glacial action which has already been alluded to. if so, it was to be expected that so long as the true origin of so singular a deposit remained undiscovered, erroneous theories and terms would be invented in the effort to solve the problem. these inventions would inevitably retard the reception of more correct views which a wider field of observation might afterwards suggest. the term "diluvium" was for a time the popular name of the boulder formation, because it was referred by some geologists to the deluge. others retained the name as expressive of their opinion that a series of diluvial waves raised by hurricanes and storms, or by earthquakes, or by the sudden upheaval of land from the bed of the sea, had swept over the continents, carrying with them vast masses of mud and heavy stones, and forcing these stones over rocky surfaces so as to polish and imprint upon them long furrows and striæ. but no explanation was offered why such agency should have been developed more energetically in modern times than at former periods of the earth's history, or why it should be displayed in its fullest intensity in northern latitudes; for it is important to insist on the fact, that the boulder formation is a _northern_ phenomenon. even the southern extension of the drift, or the large erratics found in the alps and the surrounding lands, especially their occurrence round the highest parts of the chain, offers such an exception to the general rule as confirms the glacial hypothesis; for it shows that the transportation of stony fragments to great distances, and the striation, polishing, and grooving of solid floors of rock, are here again intimately connected with accumulations of perennial snow and ice. that there is some intimate connection between a cold or northern climate and the various geological appearances now commonly called glacial, cannot be doubted by any one who has compared the countries bordering the baltic with those surrounding the mediterranean. the smoothing and striation of rocks, and the erratics, are traced from the sea-shore to the height of feet above the level of the baltic, whereas such phenomena are wholly wanting in countries bordering the mediterranean; and their absence is still more marked in the equatorial parts of asia, africa, and america; but when we cross the southern tropic, and reach chili and patagonia, we again encounter the boulder formation, between the latitude ° s. and cape horn, with precisely the same characters which it assumes in europe. the evidence as to climate derived from the organic remains of the drift is, as we have seen, in perfect harmony with the conclusions above alluded to, the former habits of the species of mollusca being accurately ascertainable, inasmuch as they belong to species still living, and known to have at present a wide range in northern seas. but if we are correct in assuming that the northern hemisphere was considerably colder than now during the period under consideration, owing probably to the greater area and height of arctic lands, and to the quantity of icebergs which such a geographical state of things would generate, it may be well to reflect before we proceed farther on the entire modification which extreme cold would produce in the operation of those causes spoken of in the sixth chapter as most active in the formation of alluvium. a large part of the materials derived from the detritus of rocks, which in warm climates would go to form deltas, or would be regularly stratified by marine currents, would, under arctic influences, assume a superficial and alluvial character. instead of mud being carried farther from a coast than sand, and sand farther out than pebbles,--instead of dense stratified masses being heaped up in limited areas,--nearly the whole materials, whether coarse or fine, would be conveyed by ice to equal distances, and huge fragments, which water alone could never move, would be borne for hundreds of miles without having their edges worn or fractured; and the earthy and stony masses, when melted out of the frozen rafts, would be scattered at random over the submarine bottom, whether on mountain tops or in low plains, with scarcely any relation to the inequalities of the ground, settling on the crests or ridges of hills in tranquil water as readily as in valleys and ravines. occasionally, in those deep and uninhabited parts of the ocean, never reached by any but the finest sediment in a normal state of things, the bottom would become densely overspread by gravel, mud, and boulders. in the western hemisphere, both in canada and as far south as the th and even th parallel of latitude in the united states, we meet with a repetition of all the peculiarities which distinguish the european boulder formation. fragments of rock have travelled for great distances from north to south; the surface of the subjacent rock is smoothed, striated, and fluted; unstratified mud or _till_ containing boulders is associated with strata of loam, sand, and clay, usually devoid of fossils. where shells are present, they are of species still living in northern seas, and half of them identical with those already enumerated as belonging to european drift degrees of latitude farther north. the fauna also of the glacial epoch in north america is less rich in species than that now inhabiting the adjacent sea, whether in the gulf of st. lawrence, or off the shores of maine, or in the bay of massachusetts. at the southern extremity of its course, moreover, it presents an analogy with the drift of the south of ireland, by blending with a more southern fauna, as for example at brooklyn near new york, in lat. ° n., where, according to mm. redfield and desor, _venus mercenaria_ and other southern species of shells begin to occur as fossils in the drift. the extension on the american continent of the range of erratics during the pleistocene period to lower latitudes than they reached in europe, agrees well with the present southward deflection of the isothermal lines, or rather the lines of equal winter temperature. formerly, as now, a more extreme climate and a more abundant supply of floating ice prevailed on the western side of the atlantic. another resemblance between the distribution of the drift fossils in europe and north america has yet to be pointed out. in norway, sweden, and scotland, as in canada and the united states, the marine shells are confined to very moderate elevations above the sea (between and feet), while the erratic blocks and the grooved and polished surfaces of rock extend to elevations of several thousand feet. [illustration: fig. . cross section. k. mr. ryland's house. _h_. clay and sand of higher grounds, with _saxicava_, &c. _g_. gravel with boulders. _f_. mass of _saxicava rugosa_, feet thick. _e_. sand and loam with _mya truncata_, _scalaria groenlandica_, &c. _d_. drift, with boulders of syenite, &c. _c_. yellow sand. _b_. laminated clay, feet thick. a. horizontal lower silurian strata. b. valley re-excavated.] i described in the fossil shells collected by captain bayfield from strata of drift at beauport near quebec, in lat. °, and drew from them the inference that they indicated a more northern climate, the shells agreeing in great part with those of uddevalla in sweden.[ -a] the shelly beds attain at beauport and the neighbourhood a height of , , and sometimes feet above the sea, and dispersed through some of them are large boulders of granite, which could not have been propelled by a violent current, because the accompanying fragile shells are almost all entire. they seem, therefore, said captain bayfield, writing in , to have been dropped down from melting ice, like similar stones which are now annually deposited in the st. lawrence.[ -b] i visited this locality in , and made the annexed section, fig. ., which will give an idea of the general position of the drift in canada and the united states. i imagine that the whole of the valley b was once filled up with the beds _b_, _c_, _d_, _e_, _f_, which were deposited during a period of subsidence, and that subsequently the higher country (_h_) was submerged and overspread with drift. the partial re-excavation of b took place when this region was again uplifted above the sea to its present height. among the twenty-three species of fossil shells collected by me from these beds at beauport, all were of recent northern species, except one, which is unknown as living, and may be extinct (see fig. .). i also examined the same formation farther up the valley of the st. lawrence, in the suburbs of montreal, where some of the beds of loam are filled with great numbers of the _mytilus edulis_, or our common european mussel, retaining both its valves and purple colour. this shelly deposit, containing _saxicava rugosa_ and other characteristic marine shells, also occurs at an elevated point on the mountain of montreal, feet above the level of the sea.[ -a] [illustration: fig. . _astarte laurentiana._ _a._ outside. _b._ inside of right valve. _c._ inside of left valve.] in my account of canada and the united states, published in , i announced the conclusion to which i had then arrived, that to explain the position of the erratics and the polished surfaces of rocks, and their striæ and flutings, we must assume first a gradual submergence of the land in north america, after it had acquired its present outline of hill and valley, cliff and ravine, and then its re-emergence from the ocean. when the land was slowly sinking, the sea which bordered it was covered with islands of floating ice coming from the north, which, as they grounded on the coast and on shoals, pushed along such loose materials of sand and pebbles as lay strewed over the bottom. by this force all angular and projecting points were broken off, and fragments of hard stone, frozen into the lower surface of the ice, had power to scoop out grooves in the subjacent solid rock. the sloping beach, as well as the floor of the ocean, might be polished and scored by this machinery; but no flood of water, however violent, or however great the quantity of detritus or size of the rocky fragments swept along by it, could produce such long, perfectly straight and parallel furrows, as are everywhere visible in the niagara district, and generally in the region north of the th parallel of latitude.[ -b] by the hypothesis of such a slow and gradual subsidence of the land we may account for the fact that almost everywhere in n. america and northern europe the boulder formation rests on a polished and furrowed surface of rock,--a fact by no means obliging us to imagine, as some think, that the polishing and grooving action was, as a whole, anterior in date to the transportation of the erratics. during the successive depression of high land, varying originally in height from to feet above the sea-level, every portion of the surface would be brought down by turns to the level of the ocean, so as to be converted first into a coast-line, and then into a shoal; and at length, after being well scored by the stranding upon it of thousands of icebergs, might be sunk to a depth of several hundred fathoms. by the constant depression of land, the coast would recede farther and farther from the successively formed zones of polished and striated rock, each outer zone becoming in its turn so deep under water as to be no longer grated upon by the heaviest icebergs. such sunken areas would then simply serve as receptacles of mud, sand, and boulders dropped from melting ice, perhaps to a depth scarcely, if at all, inhabited by testacea and zoophytes. meanwhile, during the formation of the unstratified and unfossiliferous mass in deeper water, the smoothing and furrowing of shoals and beaches is still going on elsewhere upon and near the coast in full activity. if at length the subsidence should cease, and the direction of the movement of the earth's crust be reversed, the sunken area covered with drift would be slowly reconverted into land. the boulder deposit, before emerging, would then for a time be brought within the action of the waves, tides, and currents, so that its upper portion, being partially disturbed, would have its materials re-arranged and stratified. streams also flowing from the land would in some places throw down layers of sediment upon the _till_. in that case, the order of superposition will be, first and uppermost, sand, loam, and gravel occasionally fossiliferous; secondly, an unstratified and unfossiliferous mass, for the most part of much older date than the preceding, with angular erratics, or with boulders interspersed; and, thirdly, beneath the whole, a surface of polished and furrowed rock. such a succession of events seems to have prevailed very widely on both sides of the atlantic, the travelled blocks having been carried in general from the north pole southwards, but mountain chains having in some cases served as independent centres of dispersion, of which the alps present the most conspicuous example. it is by no means rare to meet with boulders imbedded in drift which are worn flat on one or more of their sides, the surface being at the same time polished, furrowed, and striated. they may have been so shaped in a glacier before they reached the sea, or when they were fixed in the bottom of an iceberg as it ran aground. we learn from mr. charles martins that the glaciers of spitzbergen project from the coast into a sea between and feet deep; and that numbers of striated pebbles or blocks are there seen to disengage themselves from the overhanging masses of ice as they melt, so as to fall at once into deep water.[ -a] that they should retain such markings when again upraised above the sea ought not to surprise us, when we remember that rippled sands, and the cracks in clay dried between high and low water, and the foot-tracks of animals and rain-drops impressed on mud, and other superficial markings, are all found fossil in rocks of various ages. on the other hand, it is not difficult to account for the absence in many districts of striated and scored pebbles and boulders in glacial deposits, for they may have been exposed to the action of the waves on a coast while it was sinking beneath or rising above the sea. no shingle on an ordinary sea-beach exhibits such striæ, and at a very short distance from the termination of a glacier every stone in the bed of the torrent which gushes out from the melting ice is found to have lost its glacial markings by being rolled for a distance even of a few hundred yards. the usual dearth of fossil shells in glacial clays well fitted to preserve organic remains may, perhaps, be owing, as already hinted, to the absence of testacea in the deep sea, where the undisturbed accumulation of boulders melted out of very large bergs may take place. in the Ægean and other parts of the mediterranean, the zero of animal life, according to prof. e. forbes, is approached at a depth of about fathoms. in tropical seas it would descend farther down, just as vegetation ascends higher on the mountains of hot countries. near the pole, on the other hand, the same zero would be reached much sooner both on the hills and in the sea. if the ocean was filled with floating bergs, and a low temperature prevailed in the northern hemisphere during the glacial period, even the shallow part of the sea might have been uninhabitable, or very thinly peopled with living beings. it may also be remarked that the melting of ice in some fiords in norway freshens the water so as to destroy marine life, and famines have been caused in iceland by the stranding of icebergs drifted from the greenland coast, which have required several years to melt, and have not only injured the hay harvest by cooling the atmosphere, but have driven away the fish from the shore by chilling and freshening the sea. if the cold of the glacial epoch came on slowly, if it was long before it reached its greatest intensity, and again if it abated gradually, we may expect to find the earliest and latest formed drift less barren of organic remains than that deposited during the coldest period. we may also expect that along the southern limits of the drift during the whole glacial epoch, there would be an intimate association of transported matter of northern origin with fossil-bearing sediment, whether marine or freshwater, belonging to more southern seas, rivers, and continents. that in the united states, the _mastodon giganteus_ was very abundant after the drift period is evident from the fact that entire skeletons of this animal are met with in bogs and lacustrine deposits occupying hollows in the drift. they sometimes occur in the bottom even of small ponds recently drained by the agriculturist for the sake of the shell marl. i examined one of these spots at geneseo in the state of new york, from which the bones, skull, and tusk of a mastodon had been procured in the marl below a layer of black peaty earth, and ascertained that all the associated freshwater and land shells were of a species now common in the same district. they consisted of several species of _lymnea_, of _planorbis bicarinatus_, _physa heterostropha_, &c. in no less than six skeletons of the same species of mastodon were found in warren county, new jersey, feet below the surface, by a farmer who was digging out the rich mud from a small pond which he had drained. five of these skeletons were lying together, and a large part of the bones crumbled to pieces as soon as they were exposed to the air. but nearly the whole of the other skeleton, which lay about feet apart from the rest, was preserved entire, and proved the correctness of cuvier's conjecture respecting this extinct animal, namely, that it had twenty ribs like the living elephant. from the clay in the interior within the ribs, just where the contents of the stomach might naturally have been looked for, seven bushels of vegetable matter were extracted. i submitted some of this matter to mr. a. henfrey of london for microscopic examination, and he informs me that it consists of pieces of small twigs of a coniferous tree of the cypress family, probably the young shoots of the white cedar, _thuja occidentalis_, still a native of north america, on which therefore we may conclude that this extinct mastodon once fed. another specimen of the same quadruped, the most complete and probably the largest ever found, was exhumed in in the town of newburg, new york, the length of the skeleton being feet, and its height feet. the anchylosing of the last two ribs on the right side afforded dr. john c. warren a true gauge for the space occupied by the intervertebrate substance, so as to enable him to form a correct estimate of the entire length. the tusks when discovered were feet long, but a part only could be preserved. the large proportion of animal matter in the tusk, teeth, and bones of some of these fossil mammalia is truly astonishing. it amounts in some cases, as dr. c. t. jackson has ascertained by analysis, to per cent., so that when all the earthy ingredients are removed by acids, the form of the bone remains as perfect, and the mass of animal matter is almost as firm, as in a recent bone subjected to similar treatment. it would be rash, however, to infer from such data that these quadrupeds were mired in _modern_ times, unless we use that term strictly in a geological sense. i have shown that there is a fluviatile deposit in the valley of the niagara, containing shells of the genera _melania_, _lymnea_, _planorbis_, _valvata_, _cyclas_, _unio_, and _helix_, &c., all of recent species, from which the bones of the great mastodon have been taken in a very perfect state. yet the whole excavation of the ravine, for many miles below the falls, has been slowly effected since that fluviatile deposit was thrown down. whether or not, in assigning a period of more than , years for the recession of the falls from queenstown to their present site, i have over or under estimated the time required for that operation, no one can doubt that a vast number of centuries must have elapsed before so great a series of geographical changes were brought about as have occurred since the entombment of this elephantine quadruped. the freshwater gravel which incloses it is decidedly of much more modern origin than the drift or boulder clay of the same region.[ -a] other extinct animals accompany the _mastodon giganteus_ in the post-glacial deposits of the united states, among which the _castoroides ohioensis_, foster and wyman, a huge rodent allied to the beaver, and the _capybara_ may be mentioned. but whether the "loess," and other freshwater and marine strata of the southern states, in which skeletons of the same mastodon are mingled with the bones of the megatherium, mylodon, and megalonyx, were contemporaneous with the drift, or were of subsequent date, is a chronological question still open to discussion. it appears clear, however, from what we know of the tertiary fossils of europe--and i believe the same will hold true in north america--that many species of testacea and some mammalia, which existed prior to the glacial epoch, survived that era. as european examples among the warm-blooded quadrupeds, the _elephas primigenius_ and _rhinoceros tichorinus_ may be mentioned. as to the shells, whether fresh water, terrestrial, or marine, they need not be enumerated here, as allusion will be made to them in the sequel, when the pliocene tertiary fossils of suffolk are described. the fact is important, as refuting the hypothesis that the cold of the glacial period was so intense and universal as to annihilate all living creatures throughout the globe. that the cold was greater for a time than it is now in certain parts of siberia, europe, and north america, will not be disputed; but, before we can infer the universality of a colder climate, we must ascertain what was the condition of other parts of the northern, and of the whole southern, hemisphere at the time when the scandinavian, british, and alpine erratics were transported into their present position. it must not be forgotten that a great deposit of drift and erratic blocks is now in full progress of formation in the southern hemisphere, in a zone corresponding in latitude to the baltic, and to northern italy, switzerland, france, and england. should the uneven bed of the southern ocean be hereafter converted by upheaval into land, the hills and valleys will be strewed over with transported fragments, some derived from the antarctic continent, others from islands covered with glaciers, like south georgia, which must now be centres of the dispersion of drift, although situated in a latitude, agreeing with that of the cumberland mountains in england. not only are these operations going on between the th and th parallels of latitude south of the line, while the corresponding zone of europe is free from ice; but, what is still more worthy of remark, we find in the southern hemisphere itself, only miles distant from south georgia, where the perpetual snow reaches to the sea-beach, lands covered with forests, as in terra del fuego. there is here no difference of latitude to account for the luxuriance of vegetation in one spot, and the absolute want of it in the other; but among other refrigerating causes in south georgia may be enumerated the countless icebergs which float from the antarctic zone, and which chill, as they melt, the waters of the ocean, and the surrounding air, which they fill with dense fogs. i have endeavoured in the "principles of geology," chapters . and ., to point out the intimate connexion of climate and the physical geography of the globe, and the dependence of the mean annual temperature, not only on the height of the dry land, but on its distribution in high or low latitudes at particular epochs. if, for example, at certain periods of the past, the antarctic land was less elevated and less extensive than now, while that at the north pole was higher and more continuous, the conditions of the northern and southern hemispheres might have been the reverse of what we now witness in regard to climate, although the mountains of scandinavia, scotland, and switzerland, may have been less elevated than at present. but if in both of the polar regions a considerable area of elevated dry land existed, such a concurrence of refrigerating conditions in both hemispheres might have created for a time an intensity of cold never experienced since; and such probably was the state of things during that period of submergence to which i have alluded in this chapter. _alpine erratics._--although the arctic regions constitute the great centre from which erratics have travelled southwards in all directions in europe and north america, yet there are some mountains, as i have already stated, like those of north wales and the alps, which have served as separate and independent centres for the dispersion of blocks. in illustration of this fact, the alps deserve particular attention, not only from their magnitude, but because they lie beyond the ordinary limits of the "northern drift" of europe, being situated between the th and th degrees of north latitude. on the flanks of these mountains, and on the subalpine ranges of hills or plains adjoining them, those appearances which have been so often alluded to, as distinguishing or accompanying the drift, between the th and th parallels of north latitude, suddenly reappear, to assume in a more southern country their most exaggerated form. where the alps are highest, the largest erratic blocks have been sent forth, as, for example, from the regions of mont blanc and monte rosa, into the adjoining parts of france, switzerland, austria, and italy, while in districts where the great chain sinks in altitude, as in carinthia, carniola, and elsewhere, no such rocky fragments, or a few only and of smaller bulk, have been detached and transported to a distance. in the year , m. venetz first announced his opinion that the alpine glaciers must formerly have extended far beyond their present limits, and the proofs appealed to by him in confirmation of this doctrine were afterwards acknowledged by m. charpentier, who strengthened them by new observations and arguments, and declared, in , his conviction that the glaciers of the alps must once have reached as far as the jura, and have carried thither their moraines across the great valley of switzerland. m. agassiz, after several excursions in the alps with m. charpentier, and after devoting himself some years to the study of glaciers, published, in , an admirable description of them, and of the marks which attest the former action of great masses of ice over the entire surface of the alps and the surrounding country.[ -a] he pointed out that the surface of every large glacier is strewed over with gravel and stones detached from the surrounding precipices by frost, rain, lightning, or avalanches. and he described more carefully than preceding writers the long lines of these stones, which settle on the sides of the glacier, and are called the lateral moraines; those found at the lower end of the ice being called terminal moraines. such heaps of earth and boulders every glacier pushes before it when advancing, and leaves behind it when retreating. when the alpine glacier reaches a lower and warmer situation, about or feet above the sea, it melts so rapidly that, in spite of the downward movement of the mass, it can advance no farther. its precise limits are variable from year to year, and still more so from century to century; one example being on record of a recession of half a mile in a single year. we also learn from m. venetz, that whereas, between the eleventh and fifteenth centuries, all the alpine glaciers were less advanced than now, they began in the seventeenth and eighteenth centuries to push forward so as to cover roads formerly open, and to overwhelm forests of ancient growth. these oscillations enable the geologist to note the marks which they leave behind them as they retrograde, and among these the most prominent, as before stated, are the terminal moraines, or mounds of unstratified earth and stones, often divided by subsequent floods into hillocks, which cross the valley like ancient earth-works, or embankments made to dam up the river. some of these transverse barriers were formerly pointed out by saussure below the glacier of the rhone, as proving how far it had once transgressed its present boundaries. on these moraines we see many large angular fragments, which, having been carried along on the surface of the ice, have not had their edges worn off by friction; but the greater number of the boulders, even those of large size, have been well rounded, not by the power of water, but by the mechanical force of the ice, which has pushed them against each other, or against the rocks flanking the valley. others have fallen down the numerous fissures which intersect the glacier, where, being subject to the pressure of the whole mass of ice, they have been forced along, and either well rounded or ground down into sand, or even the finest mud, of which the moraine is largely constituted. as the terminal moraines are the most prominent of all the monuments left by a receding glacier, so are they the most liable to obliteration; for violent floods or debacles are often occasioned in the alps by the sudden bursting of what are called glacier-lakes. these temporary sheets of water are caused by the damming up of a river by a glacier which has increased during a succession of cold seasons, and, descending from a tributary into the main valley, has crossed it from side to side. on the failure of this icy barrier, the accumulated waters are let loose, which sweep away and level all transverse mounds of gravel and loose boulder below, and spread their materials in confused and irregular beds over the river-plain. another mark of the former action of glaciers, in situations where they exist no longer, is the polished, striated, and grooved surfaces of rocks already alluded to. stones which lie underneath the glacier and are pushed along by it, sometimes adhere to the ice, and as the mass glides slowly along at the rate of a few inches, or at the utmost two or three feet, per day, abrade, groove, and polish the rock, and the larger blocks are reciprocally grooved and polished by the rock on their lower sides. as the forces both of pressure and propulsion are enormous, the sand, acting like emery, polishes the surface; the pebbles, like coarse gravers, scratch and furrow it; and the large stones scoop out grooves in it. another effect also of this action, not yet adverted to, is called "roches moutonnées." projecting eminences of rock are smoothed and worn into the shape of flattened domes, where the glaciers have passed over them. although the surface of almost every kind of rock, when exposed in the open air, wastes away by decomposition, yet some retain for ages their polished and furrowed exterior; and, if they are well protected by a covering of clay or turf, these marks of abrasion seem capable of enduring for ever. they have been traced in the alps to great heights above the present glaciers, and to great horizontal distances beyond them. there are also found, on the sides of the swiss valleys, round and deep holes, with polished sides, such holes as waterfalls make in the solid rock, but in places remote from running waters, and where the form of the surface will not permit us to suppose that any cascade could ever have existed. similar cavities are common in hard rocks, such as gneiss, in sweden, where they are called _giant caldrons_, and are sometimes feet and more in depth; but in the alps and jura they often pass into spoon-shaped excavations and prolonged gutters. we learn from m. agassiz that hollows of this form are now cut out by streams of water, which flow along the surface of glaciers, and then fall into fissures which are open to the bottom. here, forming a cascade, the stream cuts a round cavity in the rock with the gravel and sand, which it either finds there or carries down with it, and causes to rotate; and, as it usually happens that the glacier is advancing, a locomotive cascade is produced, which converts the first circular hole into a deep groove. another effect of a glacier is to lodge a ring of stones round the summit of a conical peak which may happen to project through the ice. if the glacier is lowered greatly by melting, these circles of large angular fragments, which are called "perched blocks," are left in a singular situation near the top of a steep hill or pinnacle, the lower parts of which may be destitute of boulders. _alpine blocks on the jura._--now some or all the marks above enumerated,--the moraines, erratics, polished surfaces, domes, striæ, caldrons, and perched rocks, are observed in the alps at great heights above the present glaciers, and far below their actual extremities; also in the great valley of switzerland, miles broad; and almost everywhere on the jura, a chain which lies to the north of this valley. the average height of the jura is about one third that of the alps, and is now entirely destitute of glaciers, yet it presents almost everywhere similar moraines, and the same polished and grooved surfaces, and water-worn cavities. the erratics, moreover, which cover it, present a phenomenon which has astonished and perplexed the geologist for more than half a century. no conclusion can be more incontestible than that these angular blocks of granite, gneiss, and other crystalline formations, came from the alps, and that they have been brought for a distance of miles and upwards across one of the widest and deepest valleys of the world, so that they are now lodged on the hills and valleys of a chain composed of limestone and other formations, altogether distinct from those of the alps. their great size and angularity, after a journey of so many leagues, has justly excited wonder; for hundreds of them are as large as cottages; and one in particular, celebrated under the name of pierre à bot, rests on the side of a hill about feet above the lake of neufchatel, and is no less than feet in diameter. it will be remarked that these blocks on the jura offer an exception to the rule before laid down, as applicable in general to erratics, since they have gone from south to north. some of the largest masses of granite and gneiss have been found to contain , and , cubic feet of stone, and one limestone block near devens, which has travelled miles, contains , cubic feet, its angles being sharp and unworn.[ -a] von buch, escher, and studer have shown, from an examination of the mineral composition of the boulders, that those on the western jura, near neufchatel, have come from the region of mont blanc and the valais; those on the middle parts of the jura from the bernese oberland; and those on the eastern jura from the alps of the small cantons, glaris, schwytz, uri, and zug. the blocks, therefore, of these three great districts have been derived from parts of the alps nearest to the localities in the jura where we now find them, as if they had crossed the great valley in a direction at right angles to its length: the most western stream having followed the course of the rhone; the central, that of the aar; and the eastern, that of the two great rivers, reuss and limmat. the non-intermixture of these groups of travelled fragments, except near their confines, was always regarded as most enigmatical by those who adopted the opinion of saussure, that they were all whirled along by a rapid current of muddy water rushing from the alps. m. charpentier first suggested, as before mentioned, that the swiss glaciers once reached continuously to the jura, and conveyed to them these erratics; but at the same time he conceived that the alps were formerly higher than now. m. agassiz, on the other hand, instead of introducing distinct and separate glaciers, imagines that the whole valley of switzerland was filled with ice, and that one great sheet of it extended from the alps to the jura, when the two chains were of the same height as now relatively to each other. such an hypothesis labours under this difficulty, that the difference of altitude, when distributed over a space of miles, gives an inclination of no more than two degrees, or far less than that of any known glaciers. it has, however, since received the able support of professor james forbes, in his excellent work on the alps, published in . in the theory which i formerly advanced, jointly with mr. darwin[ -b], it was suggested that the erratics may have been transferred by floating ice to the jura, at the time when the greater part of that chain, and the whole of the swiss valley to the south, was under the sea. at that period the alps may have attained only half their present altitude, and may yet have constituted a chain as lofty as the chilian andes, which, in a latitude corresponding to switzerland, now send down glaciers to the head of every sound, from which icebergs, covered with blocks of granite, are floated seaward.[ -a] opposite that part of chili where the glaciers abound is situated the island of chiloe, miles in length, with a breadth of miles, running parallel to the continent. the channel which separates it from the main land is of considerable depth, and miles broad. parts of its surface, like the adjacent coast of chili, are overspread with recent marine shells, showing an upheaval of the land during a very modern period; and beneath these shells is a boulder deposit, in which mr. darwin found large travelled blocks. one group of fragments were of granite, which had evidently come from the andes, while in another place angular blocks of syenite were met with. their arrangement may have been due to successive crops of icebergs issuing from different sounds, to the heads of which glaciers descend from the andes. these icebergs, taking their departure year after year from distinct points, may have been stranded repeatedly, in equally distinct groups, in bays or creeks of chiloe, and on islets off the coast, so as afterwards to appear, some on hills and others in valleys, when that country and the bed of the adjacent sea had been upheaved. a continuance in future of the elevatory movement, in the region of the andes and of chiloe, might cause the former chain to rival the alps in altitude, and give to chiloe a height equal to that of the jura. the same rise might dry up the channel between chiloe and the main land, so that it would then represent the great valley of switzerland. in the course of these changes, all parts of chiloe and the intervening strait, having in their turn been a sea-shore, may have been polished and scratched by coast-ice, and by innumerable icebergs running aground and grating on the bottom. if we apply this hypothesis to switzerland and the jura, we are by no means precluded from the supposition that, in proportion as the land acquired additional height, and the bed of the sea emerged, the jura itself may have had its glaciers; and those existing in the alps, which had at first extended to the sea, may, during some part of the period of upheaval, have been prolonged much farther into the valleys than now. at a later period, when the climate grew milder, these glaciers may have entirely disappeared from the jura, and may have receded in the alps to their present limits, leaving behind them in both districts those moraines which now attest the former extension of the ice.[ -b] _meteorites in drift._--before concluding my remarks on the northern drift of the old world, i shall refer to a fact recently announced, the discovery of a meteoric stone at a great depth in the alluvium of northern asia. erman, in his archives of russia for (p. .), cites a very circumstantial account drawn up by a russian miner of the finding of a mass of meteoric iron in the auriferous alluvium of the altai. some small fragments of native iron were first met with in the gold-washings of petropawlowsker in the mrassker circle; but though they attracted attention, it was supposed that they must have been broken off from the tools of the workmen. at length, at the depth of feet inches from the surface, they dug out a piece of iron weighing - / pounds, of a steel-grey colour, somewhat harder than ordinary iron, and, on analysing it, found it to consist of native iron, with a small proportion of nickel, as usual in meteoric stones. it was buried in the bottom of the deposit where the gravel rested on a flaggy limestone. much brown iron ore, as well as gold, occurs in the same gravel, which appears to be part of that extensive auriferous formation in which the bones of the mammoth, the _rhinoceros tichorhinus_, and other extinct quadrupeds abound. no sufficient data are supplied to enable us to determine whether it be of post-pliocene or newer pliocene date. we ought not, i think, to feel surprise that we have not hitherto succeeded in detecting the signs of such aërolites in older rocks, for, besides their rarity in our own days, those which fell into the sea (and it is with marine strata that geologists have usually to deal), being chiefly composed of native iron, would rapidly enter into new chemical combinations, the water and mud being charged with chloride of sodium and other salts. we find that anchors, cannon, and other cast-iron implements which have been buried for a few hundred years off our english coast have decomposed in part or entirely, turning the sand and gravel which enclosed them into a conglomerate, cemented together by oxide of iron. in like manner meteoric iron, although its rusting would be somewhat checked by the alloy of nickel, could scarcely ever fail to decompose in the course of thousands of years, becoming oxide, sulphuret or carbonate of iron, and its origin being then no longer distinguishable. the greater the antiquity of rocks,--the oftener they have been heated and cooled, permeated by gases or by the waters of the sea, the atmosphere or mineral springs,--the smaller must be the chance of meeting with a mass of native iron unaltered; but the preservation of the ancient meteorite of the altai, and the presence of nickel in these curious bodies, renders the recognition of them in deposits of remote periods less hopeless than we might have anticipated. footnotes: [ -a] geol. trans. d series, vol. vi. p. . mr. smith of jordanhill had arrived at similar conclusions as to climate from the shells of the scotch pleistocene deposits. [ -b] proceedings of geol. soc. no. . p. . [ -a] travels in n. america, vol. ii. p. . [ -b] ibid. p. . chap. xix. [ -a] bulletin soc. géol. de france, tom. iv. de sér. p. . [ -a] see travels in n. america, vol. i. chap. ii. [ -a] agassiz, etudes sur les glaciers. [ -a] archiac, hist. des progrès, &c. vol. ii. p. . [ -b] see elements of geology, d ed. . [ -a] darwin's journal, p. . [ -b] more recently sir r. murchison, having revisited the alps, has declared his opinion that "the great granitic blocks of mont blanc were translated to the jura when the intermediate country was under water."--paper read to geol. soc. london, may , . chapter xiii. newer pliocene strata and cavern deposits. chronological classification of pleistocene formations, why difficult--freshwater deposits in valley of thames--in norfolk cliffs--in patagonia--comparative longevity of species in the mammalia and testacea--fluvio-marine crag of norwich--newer pliocene strata of sicily--limestone of great thickness and elevation--alternation of marine and volcanic formations--proofs of slow accumulation--great geographical changes in sicily since the living fauna and flora began to exist--osseous breccias and cavern deposits--sicily--kirkdale--origin of stalactite--australian cave-breccias--geographical relationship of the provinces of living vertebrata and those of the fossil species of the pliocene periods--extinct struthious birds of new zealand--teeth of fossil quadrupeds. having in the last chapter treated of the boulder formation and its associated freshwater and marine strata as belonging chiefly to the close of the newer pliocene period, we may now proceed to other deposits of the same or nearly the same age. it should, however, be stated that it is difficult to draw the line of separation between these modern formations, especially when we are called upon to compare deposits of marine and freshwater origin, or these again with the ossiferous contents of caverns. if as often as the carcasses of quadrupeds were buried in alluvium during floods, or mired in swamps, or imbedded in lacustrine strata, a stream of lava had descended and preserved the alluvial or freshwater deposits, as frequently happened in auvergne (see above, p. ,), keeping them free from intermixture with strata subsequently formed, then indeed the task of arranging chronologically the whole series of mammaliferous formations might have been easy, even though many species were common to several successive groups. but when there have been oscillations in the levels of the land, accompanied by the widening and deepening of valleys at more than one period,--when the same surface has sometimes been submerged beneath the sea, after supporting forests and land quadrupeds, and then raised again, and subject during each change of level to sedimentary deposition and partial denudation,--and when the drifting of ice by marine currents or by rivers, during an epoch of intense cold, has for a season interfered with the ordinary mode of transport, or with the geographical range of species, we cannot hope speedily to extricate ourselves from the confusion in which the classification of these pleistocene formations is involved. at several points in the valley of the thames, remnants of ancient fluviatile deposits occur, which may differ considerably in age, although the imbedded land and freshwater shells in each are of recent species. at brentford, for example, the bones of the siberian mammoth, or _elephas primigenius_, and the _rhinoceros tichorhinus_, both of them quadrupeds of which the flesh and hair have been found preserved in the frozen soil of siberia, occur abundantly, with the bones of an hippopotamus, aurochs, short-horned ox, red deer, rein-deer, and great cave-tiger or lion.[ -a] a similar group has been found fossil at maidstone, in kent, and other places, agreeing in general specifically with the fossil bones detected in the caverns of england. when we see the existing rein-deer and an extinct hippopotamus in the same fluviatile loam, we are tempted to indulge our imaginations in speculating on the climatal conditions which could have enabled these genera to co-exist in the same region. wherever there is a continuity of land from polar to temperate and equatorial regions, there will always be points where the southern limit of an arctic species meets the northern range of a southern species; and if one or both have migratory habits, like the bengal tiger, the american bison, the musk ox, and others, they may each penetrate mutually far into the respective provinces of the other. there may also have been several oscillations of temperature during the periods which immediately preceded and followed the more intense cold of the glacial epoch. the strata bordering the left bank of the thames at grays thurrock, in essex, are probably of older date than those of brentford, although the associated land and freshwater shells are nearly all, if not all, identical with species now living. three of the shells, however, are no longer inhabitants of great britain; namely, _paludina marginata_ (fig. . p. .), now living in france; _unio littoralis_ (fig. . p. .), now inhabiting the loire; and _cyrena consobrina_ (fig. . p. .). the last-mentioned fossil (a recent egyptian shell of the nile) is very abundant at grays, and deserves notice, because the genus _cyrena_ is now no longer european. the rhinoceros occurring in the same beds (_r. leptorhinus_, see fig. . p. .) is of a different species from that of brentford above mentioned, and the accompanying elephant belongs to the variety called _elephas meridionalis_, which, according to mm. owen and h. von meyer, two high authorities, is the same species as the siberian mammoth, although some naturalists regard it as distinct. with the above mammalia is also found the _hippopotamus major_, and what is most remarkable in so modern and northern a deposit, a monkey, called by owen, _macacus pliocenus_. the submerged forest already alluded to (p. .) as underlying the drift at the base of the cliffs of norfolk is associated with a bed of lignite and loam, in which a great number of fossil bones occur, apparently of the same group as that of grays, just mentioned. it has sometimes been called "the elephant bed." one portion of it, which stretches out under the sea at happisburgh, was overgrown in by a bank of recent oysters, and there the fishermen dredged up, according to woodward, in the course of thirteen years, together with the oysters, above mammoths' grinders.[ -b] another portion of the same continuous stratum has yielded at bacton, cromer, and other places on the coast, the bones of a gigantic beaver (_trogontherium cuvierii_, fischer), as well as the ox, horse, and deer, and both species of rhinoceros, _r. tichorhinus_ and _r. leptorhinus_. in studying these and various other similar assemblages of fossils, we have a good exemplification of the more rapid rate at which the mammiferous fauna, as compared to the testaceous, diverges when traced backwards in time from the recent type. i have before hinted, that the longevity of species in the class of warm-blooded quadrupeds is less great than in that of the mollusca, the latter having probably more capacity for enduring those changes of climate and other external circumstances which take place in the course of ages on the earth's surface. this phenomenon is by no means confined to europe, for mr. darwin found at bahia blanca, in south america, lat. ° s., near the northern confines of patagonia, fossil remains of the extinct mammiferous genera megatherium, megalonyx, toxodon, and others, associated with shells, almost all of species already ascertained to be still living in the contiguous sea[ -a]; the marine mollusca, as well as those of rivers, lakes, or the land, having died out more slowly than the terrestrial mammalia. i alluded before (p. .) to certain marine strata overlying till near glasgow, and at other points on the clyde, in which the shells are for the most part british, with an intermixture of some arctic species; while others, about a tenth of the whole, are supposed to be extinct. this formation may also be called newer pliocene. _fluvio-marine crag of norwich._--at several places within five miles of norwich, on both banks of the yare, beds of sand, loam, and gravel, provincially termed "crag," occur, in which there is a mixture of marine, land, and freshwater shells, with ichthyolites and bones of mammalia. it is clear that these beds have been accumulated at the bottom of the sea near the mouth of a river. they form patches of variable thickness, resting on white chalk, and are covered by a dense mass of stratified flint gravel. the surface of the chalk is often perforated to the depth of several inches by the _pholas crispata_, each fossil shell still remaining at the bottom of its cylindrical cavity, now filled up with loose sand which has fallen from the incumbent crag. this species of pholas still exists and drills the rocks between high and low water on the british coast. the most common shells of these strata, such as _fusus striatus_, _turritella terebra_, _cardium edule_, and _cyprina islandica_, are now abundant in the british seas; but with them are some extinct species, such as _nucula cobboldiæ_ (fig. .) and _tellina obliqua_ (fig. .). _natica helicoides_ (fig. .) is an example of a species formerly known only as fossil, but which has now been found living in our seas. among the accompanying bones of mammalia is the _mastodon_ _angustidens_[ -a] (see fig. .), a portion of the upper jawbone with a tooth having been found by mr. wigham at postwick, near norwich. as this species has also been found in the red crag, both at sutton and at felixstow, and had hitherto been regarded as characteristic of formations older than the pleistocene, it may possibly have been washed out of the red into the norwich crag. [illustration: fig. . _nucula cobboldiæ._] [illustration: fig. . _tellina obliqua._] [illustration: fig. . _natica helicoides_, johnston.] among the bones, however, respecting the authenticity of which there seems no doubt, may be mentioned those of the elephant, horse, pig, deer, and the jaws and teeth of field mice (fig. .). i have seen the tusk of an elephant from bramerton near norwich, to which, many serpulæ were attached, showing that it had lain for some time at the bottom of the sea of the norwich crag. at thorpe, near aldborough, and at southwold, in suffolk, this fluvio-marine formation is well exposed in the sea-cliffs, consisting of sand, shingle, loam, and laminated clay. some of the strata there bear the marks of tranquil deposition, and in one section a thickness of feet is sometimes exposed to view. some of the lamellibranchiate shells have both valves united, although mixed with land and freshwater testacea, and with the bones and teeth of elephant, rhinoceros, horse, and deer. captain alexander, with whom i examined these strata in , showed me a bed rich in marine shells, in which he had found a large specimen of the _fusus striatus_, filled with sand, and in the interior of which was the tooth of a horse. among the freshwater shells i obtained the _cyrena consobrina_ (fig. . p. .), before mentioned, supposed to agree with a species now living in the nile. i formerly classed the norwich crag as older pliocene, conceiving that more than a third of the fossil testacea were extinct; but there now seems good reason for believing that several of the rarer shells obtained from these strata do not really belong to a contemporary fauna, but have been washed out of the older beds of the "red crag;" while other species, once supposed to have died out, have lately been met with living in the british seas. according to mr. searles wood, the total number of marine species does not exceed seventy-six, of which one tenth only are extinct. of the fourteen associated freshwater shells, all the species appear to be living. strata containing the same shells as those near norwich have been found by mr. bean, at bridlington, in yorkshire. _newer pliocene strata of sicily._--in no part of europe are the newer pliocene formations seen to enter so largely into the structure of the earth's crust, or to rise to such heights above the level of the sea, as in sicily. they cover nearly half the island, and near its centre, at castrogiovanni, they reach an elevation of feet. they consist principally of two divisions, the upper calcareous, the lower argillaceous, both of which may be seen at syracuse, girgenti, and castrogiovanni. according to philippi, to whom we are indebted for the best account of the tertiary shells of this island, thirty-five species out of one hundred and twenty-four obtained from the beds in central sicily are extinct. of the remainder, which still live, five species are no longer inhabitants of the mediterranean. when i visited sicily in i estimated the proportion of living species as somewhat greater, partly because i confounded with the tertiary formation of central sicily the strata at the base of etna, and some other localities, where the fossils are now proved to agree entirely with the present mediterranean fauna. philippi came to the conclusion, that in sicily there is a gradual passage from beds containing per cent. of recent shells, to those in which the whole of the fossils are identical with recent species; but his tables appear scarcely to bear out so important a generalization, several of the places cited by him in confirmation having as yet furnished no more than twenty or thirty species of testacea. the sicilian beds in question probably belong to about the same period as the norwich crag, although a geologist, accustomed to see nearly all the pleistocene formations in the north of europe occupying low grounds and very incoherent in texture, is naturally surprised to behold formations of the same age so solid and stony, of such thickness, and attaining so great an elevation above the level of the sea. the upper or calcareous member of this group in sicily consists in some places of a yellowish-white stone, like the calcaire grossier of paris, in others, of a rock nearly as compact as marble. its aggregate thickness amounts sometimes to or feet. it usually occurs in regular horizontal beds, and is occasionally intersected by deep valleys, such as those of sortino and pentalica, in which are numerous caverns. the fossils are in every stage of preservation, from shells retaining portions of their animal matter and colour, to others which are mere casts. the limestone passes downwards into a sandstone and conglomerate, below which is clay and blue marl, like that of the subapennine hills, from which perfect shells and corals may be disengaged. the clay sometimes alternates with yellow sand. south of the plain of catania is a region in which the tertiary beds are intermixed with volcanic matter, which has been for the most part the product of submarine eruptions. it appears that, while the clay, sand, and yellow limestone before mentioned were in course of deposition at the bottom of the sea, volcanos burst out beneath the waters, like that of graham island, in , and these explosions recurred again and again at distant intervals of time. volcanic ashes and sand were showered down and spread by the waves and currents so as to form strata of tuff, which are found intercalated between beds of limestone and clay containing marine shells, the thickness of the whole mass exceeding feet. the fissures through which the lava rose may be seen in many places forming what are called _dikes_. in part of the region above alluded to, as, for example, near lentini, a conglomerate occurs in which i observed many pebbles of volcanic rocks covered by full grown _serpulæ_. we may explain the origin of these by supposing that there were some small volcanic islands which may have been destroyed from time to time by the waves, as graham island has been swept away since . the rounded blocks and pebbles of solid volcanic matter, after being rolled for a time on the beach of such temporary islands, were carried at length into some tranquil part of the sea, where they lay for years, while the marine _serpulæ_ adhered to them, their shells growing and covering their surface, as they are seen adhering to the shell figured in p. . finally, the bed of pebbles was itself covered with strata of shelly limestone. at vizzini, a town not many miles distant to the s.w., i remarked another striking proof of the gradual manner in which these modern rocks were formed, and the long intervals of time which elapsed between the pouring out of distinct sheets of lava. a bed of oysters no less than feet in thickness rests upon a current of basaltic lava. the oysters are perfectly identifiable with our common eatable species. upon the oyster bed, again, is superimposed a second mass of lava, together with tuff or peperino. in the midst of the same alternating igneous and aqueous formations is seen near galieri, not far from vizzini, a horizontal bed, about a foot and a half in thickness, composed entirely of a common mediterranean coral (_caryophyllia cæspitosa_, lam.). these corals stand erect as they grew; and, after being traced for hundreds of yards, are again found at a corresponding height on the opposite side of the valley. [illustration: fig. . _caryophyllia cæspitosa_, lam. (_cladocora cæspitosa_, ehr.) _a._ stem with young stem growing from its side. _a*._ young stem of same twice magnified. _b._ portion of branch, twice magnified, with the base of a lateral branch; the exterior ridges of the main branch appearing through the lamellæ of the lateral one. _c._ transverse section of same, proving, by the integrity of the main branch, that the lateral one did not originate in a subdivision of the animal. _d._ a branch, having at its base another laterally united to it, and two young corals at its upper part. _e._ a main branch, with a full grown lateral one. _f._ a perfect terminal star.] the corals are usually branched, but not by the division of the animals as some have supposed, but by the attachment of young individuals to the sides of the older ones; and we must understand this mode of increase, in order to appreciate the time which was required for the building up of the whole bed of coral during the growth of many successive generations.[ -a] among the other fossil shells met with in these sicilian strata, which still continue to abound in the mediterranean, no shell is more conspicuous, from its size and frequent occurrence, than the great scallop, _pecten jacobæus_ (see fig. .), now so common in the neighbouring seas. we see this shell in the calcareous beds at palermo in great numbers, in the limestone at girgenti, and in that which alternates with volcanic rocks in the country between syracuse and vizzini, often at great heights above the sea. [illustration: fig. . _pecten jacobæus_; half natural size.] the more we reflect on the preponderating number of these recent shells, the more we are surprised at the great thickness, solidity, and height above the sea of the rocky masses in which they are entombed, and the vast amount of geographical change which has taken place since their origin. it must be remembered that, before they began to emerge, the uppermost strata of the whole must have been deposited under water. in order, therefore, to form a just conception of their antiquity, we must first examine singly the innumerable minute parts of which the whole is made up, the successive beds of shells, corals, volcanic ashes, conglomerates, and sheets of lava; and we must afterwards contemplate the time required for the gradual upheaval of the rocks, and the excavation of the valleys. the historical period seems scarcely to form an appreciable unit in this computation, for we find ancient greek temples, like those of girgenti (agrigentum), built of the modern limestone of which we are speaking, and resting on a hill composed of the same; the site having remained to all appearance unaltered since the greeks first colonised the island. the modern geological date of the rocks in this region leads to another singular and unexpected conclusion, namely, that the fauna and flora of a large part of sicily are of higher antiquity than the country itself, having not only flourished before the lands were raised from the deep, but even before their materials were brought together beneath the waters. the chain of reasoning which conducts us to this opinion may be stated in a few words. the larger part of the island has been converted from sea into land since the mediterranean was peopled with nearly all the living species of testacea and zoophytes. we may therefore presume that, before this region emerged, the same land and river shells, and almost all the same animals and plants, were in existence which now people sicily; for the terrestrial fauna and flora of this island are precisely the same as that of other lands surrounding the mediterranean. there appear to be no peculiar or indigenous species, and those which are now established there must be supposed to have migrated from pre-existing lands, just as the plants and animals of the neapolitan territory have colonised monte nuovo, since that volcanic cone was thrown up in the sixteenth century. such conclusions throw a new light on the adaptation of the attributes and migratory habits of animals and plants to the changes which are unceasingly in progress in the physical geography of the globe. it is clear that the duration of species is so great, that they are destined to outlive many important revolutions in the configuration of the earth's surface; and hence those innumerable contrivances for enabling the subjects of the animal and vegetable creation to extend their range; the inhabitants of the land being often carried across the ocean, and the aquatic tribes over great continental spaces. it is obviously expedient that the terrestrial and fluviatile species should not only be fitted for the rivers, valleys, plains, and mountains which exist at the era of their creation, but for others that are destined to be formed before the species shall become extinct; and, in like manner, the marine species are not only made for the deep and shallow regions of the ocean existing at the time when they are called into being, but for tracts that may be submerged or variously altered in depth during the time that is allotted for their continuance on the globe. osseous breccias and deposits in caves of the pliocene period. _sicily._--caverns filled with marine breccias, at the base of ancient sea-cliffs, have been already mentioned in the sixth chapter; and it was noticed, respecting the cave of san ciro, near palermo (p. .), that upon a bed of sand filled with sea-shells, almost all of recent species, rests a breccia (_b_, fig. .), composed of fragments of calcareous rock, and the bones of animals. in the sand at the bottom of that cave, dr. philippi found about forty-five marine shells, all clearly identical with recent species, except two or three. the bones in the incumbent breccia are chiefly those of the mammoth (_e. primigenius_), with some belonging to an hippopotamus, distinct from the recent species, and smaller than that usually found fossil. (see fig. .) several species of deer also, and, according to some accounts, the remains of a bear, were discovered. these mammalia are probably referable to the post-pliocene period. the newer pliocene tertiary limestone of the south of sicily, already described, is sometimes full of caverns; and the student will at once perceive that all the quadrupeds of which the remains are found in the stalactite of these caverns, being of later origin than the rocks, must be referable to the close of the tertiary epoch, if not of still later date. the situation of one of these caves, in the valley of sortino, is represented in the annexed section. [illustration: fig. . cross section. _a_. alluvium, } containing the remains of quadrupeds _b_, _b_. deposits in caves, } for the most part extinct. c. limestone, containing the remains of shells, of which between and per cent. are recent.] _england._--in a cave at kirkdale, about twenty-five miles n.n.e. of york, the remains of about hyænas, belonging to individuals of every age, have been detected. the species (_hyæna spelæa_) is extinct, and was larger than the fierce _hyæna crocuta_ of south africa, which it most resembled. dr. buckland, after carefully examining the spot, proved that the hyænas must have lived there; a fact attested by the quantity of their dung, which, as in the case of the living hyæna, is of nearly the same composition as bone, and almost as durable. in the cave were found the remains of the ox, young elephant, hippopotamus, rhinoceros, horse, bear, wolf, hare, water-rat, and several birds. all the bones have the appearance of having been broken and gnawed by the teeth of the hyænas; and they occur confusedly mixed in loam or mud, or dispersed through a crust of stalagmite which covers it. in these and many other cases it is supposed that portions of herbivorous quadrupeds have been dragged into caverns by beasts of prey, and have served as their food, an opinion quite consistent with the known habits of the living hyæna. no less than thirty-seven species of mammalia are enumerated by professor owen as having been discovered in the caves of the british islands, of which eighteen appear to be extinct, while the others still survive in europe. they were not washed to the spots where the fossils now occur by a great flood; but lived and died, one generation after another, in the places where they lie buried. among other arguments in favour of this conclusion may be mentioned the great numbers of the shed antlers of deer discovered in caves and in freshwater strata throughout england.[ -a] examples also occur of fissures into which animals have fallen from time to time, or have been washed in from above, together with alluvial matter and fragments of rock detached by frost, forming a mass which may be united into a bony breccia by stalagmitic infiltrations. frequently we discover a long suite of caverns connected by narrow and irregular galleries, which hold a tortuous course through the interior of mountains, and seem to have served as the subterranean channels of springs and engulphed rivers. many streams in the morea are now carrying bones, pebbles, and mud into underground passages of this kind.[ -b] if, at some future period, the form of that country should be wholly altered by subterranean movements and new valleys shaped out by denudation, many portions of the former channels of these engulphed streams may communicate with the surface, and become the dens of wild beasts, or the recesses to which quadrupeds retreat to die. certain caves of france, germany, and belgium, may have passed successively through these different conditions, and in their last state may have remained open to the day for several tertiary periods. it is nevertheless remarkable, that on the continent of europe, as in england, the fossil remains of mammalia belong almost exclusively to those of the newer pliocene and post-pliocene periods, and not to the miocene or eocene epochs, and when they are accompanied by land or river shells, these agree in great part, or entirely, with recent species. as the preservation of the fossil bones is due to a slow and constant supply of stalactite, brought into the caverns by water dropping from the roof, the source and origin of this deposit has been a subject of curious inquiry. the following explanation of the phenomenon has been recently suggested by the eminent chemist liebig. on the surface of franconia, where the limestone abounds in caverns, is a fertile soil, in which vegetable matter is continually decaying. this mould or humus, being acted on by moisture and air, evolves carbonic acid which is dissolved by rain. the rain water, thus impregnated, permeates the porous limestone, dissolves a portion of it, and afterwards, when the excess of carbonic acid evaporates in the caverns, parts with the calcareous matter, and forms stalactite. _australian cave-breccias._--ossiferous breccias are not confined to europe, but occur in all parts of the globe; and those lately discovered in fissures and caverns in australia correspond closely in character with what has been called the bony breccia of the mediterranean, in which the fragments of bone and rock are firmly bound together by a red ochreous cement. some of these caves have been examined by sir t. mitchell in the wellington valley, about miles west of sidney, on the river bell, one of the principal sources of the macquarie, and on the macquarie itself. the caverns often branch off in different directions through the rock, widening and contracting their dimensions, and the roofs and floors are covered with stalactite. the bones are often broken, but do not seem to be water-worn. in some places they lie imbedded in loose earth, but they are usually included in a breccia. the remains found most abundantly are those of the kangaroo, of which there are four species, besides which the genera _hypsiprymnus_, _phalangista_, _phascolomys_, and _dasyurus_, occur. there are also bones, formerly conjectured by some osteologists to belong to the hippopotamus, and by others to the dugong, but which are now referred by mr. owen to a marsupial genus, allied to the _wombat_. [illustration: fig. . _macropus atlas_, owen. _a._ permanent false molar, in the alveolus.] [illustration: fig. . lowest jaw of largest living species of kangaroo. (_macropus major._)] in the fossils above enumerated, several species are larger than the largest living ones of the same genera now known in australia. the annexed figure of the right side of a lower jaw of a kangaroo (_macropus atlas_, owen) will at once be seen to exceed in magnitude the corresponding part of the largest living kangaroo, which is represented in fig. . in both these specimens part of the substance of the jaw has been broken open, so as to show the permanent false molar (_a._ fig. .) concealed in the socket. from the fact of this molar not having been cut, we learn that the individual was young, and had not shed its first teeth. in fig. . a front tooth of the same species of kangaroo is represented. [illustration: fig. . incisor of _macropus_.] whether the breccias, above alluded to, of the wellington valley, appertain strictly to the pliocene period cannot be affirmed with certainty, until we are more thoroughly acquainted with the recent quadrupeds of the same district, and until we learn what species of fossil land shells, if any, are buried in the deposits of the same caves. the reader will observe that all these extinct quadrupeds of australia belong to the marsupial family, or, in other words, that they are referable to the same peculiar type of organization which now distinguishes the australian mammalia from those of other parts of the globe. this fact is one of many pointing to a general law deducible from the fossil vertebrate and invertebrate animals of the eras immediately antecedent to the human, namely, that the present geographical distribution of organic _forms_ dates back to a period anterior to the creation of existing _species_; in other words, the limitation of particular genera or families of quadrupeds, mollusca, &c., to certain existing provinces of land and sea, began before the species now contemporary with man had been introduced into the earth. mr. owen, in his excellent "history of british fossil mammals," has called attention to this law, remarking that the fossil quadrupeds of europe and asia differ from those of australia or south america. we do not find, for example, in the europæo-asiatic province fossil kangaroos or armadillos, but the elephant, rhinoceros, horse, bear, hyæna, beaver, hare, mole, and others, which still characterize the same continent. in like manner in the pampas of south america the skeletons of megatherium, megalonyx, glyptodon, mylodon, toxodon, macrauchenia, and other extinct forms, are analogous to the living sloth, armadillo, cavy, capybara, and llama. the fossil quadrumana, also associated with some of these forms in the brazilian caves, belong to the platyrrhine family of monkeys, now peculiar to south america. that the extinct fauna of buenos ayres and brazil was very modern has been shown by its relation to deposits of marine shells, agreeing with those now inhabiting the atlantic; and when in georgia in , i ascertained that the megatherium, mylodon, _harlanus americanus_ (owen), _equus curvidens_, and other quadrupeds allied to the pampean type were posterior in date to beds containing marine shells belonging to forty-five recent species of the neighbouring sea. there are indeed some cosmopolite genera, such as the mastodon (a genus of the elephant family), and the horse, which were simultaneously represented by different fossil species in europe, north america, and south america; but these few exceptions can by no means invalidate the rule which has been thus expressed by professor owen, "that in the highest organized class of animals the same forms were restricted to the same great provinces at the pliocene periods as they are at the present day." however modern, in a geological point of view, we may consider the pleistocene epoch, it is evident that causes more general and powerful than the intervention of man have occasioned the disappearance of the ancient fauna from so many extensive regions. not a few of the species had a wide range; the same megatherium, for instance, extended from patagonia and the river plata in south america, between latitudes ° and ° south, to corresponding latitudes in north america, the same animal being also an inhabitant of the intermediate country of brazil, where its fossil remains have been met with in caves. the extinct elephant, likewise, of georgia (_elephas primigenius_) has been traced in a fossil state northward from the river alatamaha, in lat. ° ' n. to the polar regions, and then again in the eastern hemisphere from siberia to the south of europe. if it be objected that, notwithstanding the adaptation of such quadrupeds to a variety of climates and geographical conditions, their great size exposed them to extermination by the first hunter tribes, we may observe that the investigations of lund and clausen in the ossiferous limestone caves of brazil have demonstrated that these large mammalia were associated with a great many smaller quadrupeds, some of them as diminutive as field mice, which have all died out together, while the land shells formerly their contemporaries still continue to exist in the same countries. as we may feel assured that these minute quadrupeds could never have been extirpated by man, so we may conclude that all the species, small and great, have been annihilated one after the other, in the course of indefinite ages, by those changes of circumstances in the organic and inorganic world which are always in progress, and are capable in the course of time of greatly modifying the physical geography, climate, and all other conditions on which the continuance upon the earth of any living being must depend.[ -a] the law of geographical relationship above alluded to, between the living vertebrata of every great zoological province and the fossils of the period immediately antecedent, even where the fossil species are extinct, is by no means confined to the mammalia. new zealand, when first examined by europeans, was found to contain no indigenous land quadrupeds, no kangaroos, or opossums, like australia; but a wingless bird abounded there, the smallest living representative of the ostrich family, called the xivi, by the natives (_apteryx_). in the fossils of the post-pliocene and pleistocene period in this same island, there is the like absence of kangaroos, opossums, wombats, and the rest; but in their place a prodigious number of well preserved specimens of gigantic birds of the struthious order, called by owen dinornis and palapteryx, which are entombed in superficial deposits. these genera comprehended many species, some of which were , some , others , and others feet in height! it seems doubtful whether any contemporary mammalia shared the land with this population of gigantic feathered bipeds. to those who have never studied comparative anatomy it may seem scarcely credible, that a single bone taken from any part of the skeleton may enable a skilful osteologist to distinguish, in many cases, the genus, and sometimes the species, of quadruped to which it belonged. although few geologists can aspire to such knowledge, which must be the result of long practice and study, they will nevertheless derive great advantage from learning what is comparatively an easy task, to distinguish the principal divisions of the mammalia by the forms and characters of their teeth. the annexed figures, all taken from original specimens, may be useful in assisting the student to recognize the teeth of many genera most frequently found fossil in europe:-- [illustration: fig. . _elephas primigenius_ (or mammoth); molar of upper jaw, right side; one third of nat. size. _a._ grinding surface. _b._ side view.] [illustration: fig. . _mastodon angustidens_ (norwich crag, postwick, also found in red crag, see p. .); second true molar, left side, upper jaw; grinding surface, nat. size. (see p. .)] [illustration: fig. . rhinoceros. _rhinoceros leptorhinus_; fossil from freshwater beds of grays, essex (see p. .); penultimate molar, lower jaw, left side; two-thirds of nat. size.] [illustration: fig. . hippopotamus. hippopotamus; from cave near palermo (see p. .); molar tooth; two-thirds of nat. size.] [illustration: fig. . pig. _sus scrofa_, lin. (common pig); from shell-marl, forfarshire; posterior molar, lower jaw, nat. size.] [illustration: fig. . horse. _equus caballus_, lin. (common horse); from the shell marl, forfarshire; second molar, lower jaw. _a._ grinding surface, two-thirds nat. size. _b._ side view of same, half nat. size.] [illustration: fig. . tapir. _tapirus americanus_; recent; third molar, upper jaw; nat. size.] [illustration: fig. . _a._ _b._ deer. elk (_cervus alces_, lin.); recent; molar of upper jaw. _a._ grinding surface. _b._ side view; two-thirds of nat. size.] [illustration: fig. . _c._ _d._ ox. ox, common, from shell marl, forfarshire; true molar upper jaw; two-thirds nat. size. _c._ grinding surface. _d._ side view.] [illustration: fig. . bear. _a._ canine tooth or tusk of bear (_ursus spelæus_); from cave near liege. _b._ molar of left side, upper jaw; one third of nat. size.] [illustration: fig. . tiger. _c._ canine tooth of tiger (_felis tigris_); recent. _d._ outside view of posterior molar, lower jaw; one-third of nat. size.] [illustration: fig. . _hyæna spelæa_; second molar, left side, lower jaw; nat. size. cave of kirkdale. (see p. .)] [illustration: fig. . teeth of a new species of _arvicola_ (field-mouse); from the norwich crag. (see p. .) _a._ grinding surface. _b._ side view of same. _c._ nat. size of a and b.] footnotes: [ -a] morris, geol. soc. proceed., . [ -b] woodward's geology of norfolk. [ -a] zool. of beagle, part . pp. . . [ -a] owen, brit. foss. mamm. . _mastodon longirostris_, kaup, see _ibid._ [ -a] i am indebted to mr. lonsdale for the details above given respecting the structure of this coral. [ -a] owen, brit. foss. mam. xxvi., and buckland, rel. dil. . . [ -b] see principles of geology. [ -a] see principles of geology, chaps. xli. to xliv. chapter xiv. older pliocene and miocene formations. strata of suffolk termed red and coralline crag--fossils, and proportion of recent species--depth of sea and climate--reference of suffolk crag to the older pliocene period--migration of many species of shells southwards during the glacial period--fossil whales--sub- apennine beds--asti, sienna, rome--miocene formations--faluns of touraine--depth of sea and littoral character of fauna--tropical climate implied by the testacea--proportion of recent species of shells--faluns more ancient than the suffolk crag--miocene strata of bordeaux and piedmont--molasse of switzerland--tertiary strata of lisbon--older pliocene and miocene formations in the united states--sewâlik hills in india. the older pliocene strata, which next claim our attention, are chiefly confined, in great britain, to the eastern part of the county of suffolk, where, like the norwich beds already described, they are called "crag," a provincial name given particularly to those masses of shelly sand which have been used from very ancient times in agriculture, to fertilize soils deficient in calcareous matter. the relative position of the "red crag" in essex to the london clay, may be understood by reference to the accompanying diagram (fig. .). [illustration: fig. . cross section.] these deposits, judging by the shells which they contain, appear, according to professor edward forbes, to have been formed in a sea of moderate depth, generally from to fathoms deep, although in some few spots perhaps deeper. but they may, nevertheless, have been accumulated at the distance of or miles from land. the suffolk crag is divisible into two masses, the upper of which has been termed the red, and the lower the coralline crag.[ -a] the upper deposit consists chiefly of quartzose sand, with an occasional intermixture of shells, for the most part rolled, and sometimes comminuted. the lower or coralline crag is of very limited extent, ranging over an area about miles in length, and or in breadth, between the rivers alde and stour. it is generally calcareous and marly--a mass of shells and small corals, passing occasionally into a soft building stone. at sudbourn, near orford, where it assumes this character, are large quarries, in which the bottom of it has not been reached at the depth of feet. at some places in the neighbourhood, the softer mass is divided by thin flags of hard limestone, and corals placed in the upright position in which they grew. the red crag is distinguished by the deep ferruginous or ochreous colour of its sands and fossils, the coralline by its white colour. both formations are of moderate thickness; the red crag rarely exceeding , and the coralline seldom amounting to , feet. but their importance is not to be estimated by the density of the mass of strata or its geographical extent, but by the extraordinary richness of its organic remains, belonging to a very peculiar type, which seems to characterize the state of the living creation in the north of europe during the older pliocene era. for a large collection of the fish, echinoderms, shells, and corals of the deposits in suffolk, we are indebted to the labours of mr. searles wood. of testacea alone he has obtained from species from the red, and from the coralline crag, about being common to each. the proportion of recent species in the new group is considered by mr. wood to be about [ -b] per cent., and that in the older or coralline about . when i examined these shells of suffolk in , with the assistance of dr. beck, mr. george sowerby, mr. searles wood, and other eminent conchologists, i came to the opinion that the extinct species predominated very decidedly in number over the living. recent investigations, however, have thrown much new light on the conchology of the arctic, scandinavian, british, and mediterranean seas. many of the species formerly known only as fossils of the crag, and supposed to have died out, have been dredged up in a living state from depths not previously explored. other recent species, before regarded as distinct from the nearest allied crag fossils, have been observed, when numerous individuals were procured, to be liable to much greater variation, both in size and form, than had been suspected, and thus have been identified. consequently, the crag fauna has been found to approach much more nearly to the recent fauna of the northern, british, and mediterranean seas than had been imagined. the analogy of the whole group of testacea to the european type is very marked, whether we refer to the large development of certain genera in number of species or to their size, or to the suppression or feeble representation of others. the indication also afforded by the entire fauna of a climate not much warmer than that now prevailing in corresponding latitudes, prepares us to believe that they are not of higher antiquity than the older pliocene era.[ -a] [illustration: fig. . section near ipswich, in suffolk. _a._ red crag. _b._ coralline crag. _c._ london clay.] the position of the red crag in essex to the subjacent london clay and chalk has been already pointed out (fig. .). whenever the two divisions are met with in the same district, the red crag lies uppermost; and, in some cases, as in the section represented in fig. ., it is observed that the older or coralline mass _b_ had suffered denudation before the newer formation _a_ was thrown down upon it. at d there is not only a distinct cliff, or feet high, of coralline crag, running in a direction n.e. and s.w., against which the red crag abuts with its horizontal layers; but this cliff occasionally overhangs. the rock composing it is drilled everywhere by _pholades_, the holes which they perforated having been afterwards filled with sand and covered over when the newer beds were thrown down. as the older formation is shown by its fossils to have accumulated in a deeper sea ( , and sometimes , fathoms deep or more), there must no doubt have been an upheaval of the sea-bottom before the cliff here alluded to was shaped out. we may also conclude that so great an amount of denudation could scarcely take place, in such incoherent materials, without many of the fossils of the inferior beds becoming mixed up with the overlying crag, so that considerable difficulty must be occasionally experienced by the palæontologist in deciding which species belong severally to each group. the red crag being formed in a shallower sea, often resembles in structure a shifting sand bank, its layers being inclined diagonally, and the planes of stratification being sometimes directed in the same quarry to the four cardinal points of the compass, as at butley. that in this and many other localities, such a structure is not deceptive or due to any subsequent concretionary re-arrangement of particles, or to mere lines of colour, is proved by each bed being made up of flat pieces of shell which lie parallel to the planes of the smaller strata. some fossils, which are very abundant in the red crag, have never been found in the white or coralline division; as, for example, the _fusus contrarius_ (fig. .), and several species of _buccinum_ (or _nassa_) and _murex_ (see figs. , .), which two genera seem wanting in the lower crag. [ illustrations: fossils characteristic of the red crag. fig. . _fusus contrarius._ fig. . _murex alveolatus._ fig. . _nassa granulata._ fig. . _cypræa coccinelloides._ fig. . half nat. size; the others nat. size.] among the bones and teeth of fishes are those of large sharks (_carcharias_), and a gigantic skate of the extinct genus _myliobates_, and many other forms, some common to our seas, and many foreign to them. the distinctness of the fossils of the coralline crag arises in part from higher antiquity, and, in some degree, from a difference in the geographical conditions of the submarine bottom. the prolific growth of corals, echini, and a prodigious variety of testacea, implies a region of deeper and more tranquil water; whereas, the red crag may have formed afterwards on the same spot, when the water was shallower. in the mean time the climate may have become somewhat cooler, and some of the zoophytes which flourished in the first period may have disappeared, so that the fauna of the red crag acquired a character somewhat more nearly resembling that of our northern seas, as is implied by the large development of certain sections of the genera _fusus_, _buccinum_, _purpura_, and _trochus_, proper to higher latitudes, and which are wanting or feebly represented in the inferior crag. some of the corals of the lower crag of suffolk belong to genera unknown in the living creation, and of a very peculiar structure; as, for example, that represented in the annexed fig. ( .), which is one of several species having a globular form. the great number and variety of these zoophytes probably indicate an equable climate, free from intense cold in winter. on the other hand, that the heat was never excessive is confirmed by the prevalence of northern forms among the testacea, such as the _glycimeris_, _cyprina_, and _astarte_. of the genus last mentioned (see fig. .) there are about fourteen species, many of them being rich in individuals; and there is an absence of genera peculiar to hot climates, such as _conus_, _oliva_, _mitra_, _fasciolaria_, _crassatella_, and others. the cowries (_cypræa_, fig. .), also, are small, and belong to a section (_trivia_) now inhabiting the colder regions. a large volute, called _voluta lamberti_ (fig. .), may seem an exception; but it differs in form from the volutes of the torrid zone, and may, like the living _voluta magellanica_, have been fitted for an extra-tropical climate. [illustration: fig. . _fascicularia aurantium_, milne edwards. family, _tubuliporidæ_, of same author. coral of extinct genus, from the inferior or coralline crag, suffolk. _a._ exterior. _b._ vertical section of interior. _c._ portion of exterior magnified. _d._ portion of interior magnified, showing that it is made up of long, thin, straight tubes, united in conical bundles.] [illustration: fig. . _astarte_ (_crassina_, lam.); species common to upper and lower crag. _astarte omalii_, lajonkaire; syn. _a. bipartita_, sow. min. con. t. . f. .; a very variable species most characteristic of the coralline crag, suffolk.] [illustration: fig. . _voluta lamberti_, young individ.] the occurrence of a species of _lingula_ at sutton is worthy of remark, as these _brachiopoda_ seem now confined to more equatorial latitudes, and the same may be said still more decidedly of a species of _pyrula_, allied to _p. reticulata_. whether, therefore, we may incline to the belief that the mean annual temperature was higher or lower than now, we may at least infer that the climate and geographical conditions were by no means the same at the period of the suffolk crag as those now prevailing in the same region. of the echinoderms of the coralline crag about eleven species are known, but some of these are in too fragmentary a condition to admit of exact comparison. of six which are the most perfect, prof. e. forbes has been able to identify three with recent species: one of which, of the genus _echinus_, is british; a second, _echinocyamus_, british and mediterranean; and a third, _echinus monilis_, a mediterranean species, also found fossil in the faluns of touraine. one of the most interesting conclusions deduced from a careful comparison of the shells of these british older pliocene strata and those now inhabiting our seas, has been pointed out by prof. e. forbes. it appears that, during the glacial period, a period intermediate, as we have seen, between that of the crag and our own times, many shells, previously established in the temperate zone, retreated southwards to avoid an uncongenial climate. the professor has given a list of fifty shells which inhabited the british seas while the coralline and red crag were forming, and which are wanting in the pleistocene or glacial deposits. they must, therefore, after their migration to the south, have made their way northwards again. in corroboration of these views, it is stated that all these fifty species occur fossil in the newer pliocene strata of sicily, southern italy, and the grecian archipelago, where they may have enjoyed, during the era of floating icebergs, a climate resembling that now prevailing in higher european latitudes.[ -a] in the red crag at felixstow, in suffolk, professor henslow has found the ear-bones of no less than four species of cetacea, which, according to mr. owen, are the remains of true whales of the family _balænidæ_. mr. wood is of opinion that these cetacea may be of the age of the red crag, or if not that they may be derived from the destruction of beds of coralline crag. i agree with him that the supposition of their having been washed out of the london clay, in which no _balænidæ_ have yet been met with, is improbable. strata containing fossil shells, like those of the suffolk crag, above described, have been found at antwerp, and on the banks of the scheldt below that city. in i observed a small patch of them near valognes, in normandy; and there is also a deposit containing similar fossils at st. george bohon, and several places a few leagues to the s. of carentan, in normandy; but they have never been traced farther southwards. _subapennine strata._--the apennines, it is well known, are composed chiefly of secondary rocks, forming a chain which branches off from the ligurian alps and passes down the middle of the italian peninsula. at the foot of these mountains, on the side both of the adriatic and the mediterranean, are found a series of tertiary strata, which form, for the most part, a line of low hills occupying the space between the older chain and the sea. brocchi, as we have seen (p. .), was the first italian geologist who described this newer group in detail, giving it the name of the subapennines; and he classed all the tertiary strata of italy, from piedmont to calabria, as parts of the same system. certain mineral characters, he observed, were common to the whole; for the strata consist generally of light brown or blue marl, covered by yellow calcareous sand and gravel. there are also, he added, some species of fossil shells which are found in these deposits throughout the whole of italy. we have now, however, satisfactory evidence that the subapennine beds of brocchi belong, at least, to three periods. to the miocene we can refer a portion of the strata of piedmont, those of the hill of the superga, for example; to the older pliocene, part of the strata of northern italy, of tuscany, and of rome; while the tufaceous formations of naples, of ischia, and the calcareous strata of otranto, are referable to the newer pliocene, and in great part to the post-pliocene period. that there is a considerable correspondence in the mineral composition of these different italian groups is undeniable; but not that exact resemblance which should lead us to assume a precise identity of age, unless the fossil remains agreed very closely. it is now indispensable that a new scrutiny should be made in each particular district, of the fossils derived from the upper and lower beds--especially such localities as asti and parma, where the formation attains a great thickness; and at sienna, where the shells of the incumbent yellow sand are generally believed to approach much more nearly, as a whole, to the recent fauna of the mediterranean than those in the subjacent blue marl. the greyish brown or blue marl of the subapennine formation is very aluminous, and usually contains much calcareous matter and scales of mica. near parma it attains a thickness of feet, and is charged throughout with marine shells, some of which lived in deep, others in shallow water, while a few belong to freshwater genera, and must have been washed in by rivers. among these last i have seen the common _limnea palustris_ in the blue marl, filled with small marine shells. the wood and leaves, which occasionally form beds of lignite in the same deposit, may have been carried into the sea by similar causes. the shells, in general, are soft when first taken from the marl, but they become hard when dried. the superficial enamel is often well preserved, and many shells retain their pearly lustre, part of their external colour, and even the ligament which unites the valves. no shells are more usually perfect than the microscopic foraminifera, which abound near sienna, where more than a thousand full-grown individuals may be sometimes poured out of the interior of a single univalve of moderate dimensions. the other member of the subapennine group, the yellow sand and conglomerate, constitutes, in most places, a border formation near the junction of the tertiary and secondary rocks. in some cases, as near the town of sienna, we see sand and calcareous gravel resting immediately on the apennine limestone, without the intervention of any blue marl. alternations are there seen of beds containing fluviatile shells, with others filled exclusively with marine species; and i observed oysters attached to many limestone pebbles. this appears to have been a point where a river, flowing from the apennines, entered the sea when the tertiary strata were formed. the sand passes in some districts into a calcareous sandstone, as at san vignone. its general superposition to the marl, even in parts of italy and sicily where the date of its origin is very distinct, may be explained if we consider that it may represent the deltas of rivers and torrents, which gained upon the bed of the sea where blue marl had previously been deposited. the latter, being composed of the finer and more transportable mud, would be conveyed to a distance, and first occupy the bottom, over which sand and pebbles would afterwards be spread, in proportion as rivers pushed their deltas farther outwards. in some large tracts of yellow sand it is impossible to detect a single fossil, while in other places they occur in profusion. occasionally the shells are silicified, as at san vitale, near parma, from whence i saw two individuals of recent species, one freshwater and the other marine (_limnea palustris_, and _cytherea concentrica_, lam.), both perfectly converted into flint. _rome._--the seven hills of rome are composed partly of marine tertiary strata, those of monte mario, for example, of the older pliocene period, and partly of superimposed volcanic tuff, on the top of which are usually cappings of a fluviatile and lacustrine deposit. thus, on mount aventine, the vatican, and the capitol, we find beds of calcareous tufa with incrusted reeds, and recent terrestrial shells, at the height of about feet above the alluvial plain of the tiber. the tusk of the mammoth has been procured from this formation, but the shells appear to be all of living species, and must have been embedded when the summit of the capitol was a marsh, and constituted one of the lowest hollows of the country as it then existed. it is not without interest that we thus discover the extremely recent date of a geological event which preceded an historical era so remote as the building of rome. miocene formations. _faluns of touraine._--the miocene strata, corresponding with those named by many geologists "middle tertiary," will next claim our attention. near the towns of dinan and rennes, in brittany, and again in the provinces bordering the loire, a tertiary formation, containing another assemblage of fossils, is met with, to which the name of _faluns_ has been long given by the french agriculturists, who spread the shelly sand and marl over the land, in the same manner as the crag was formerly much used in suffolk. isolated masses of these faluns occur from near the mouth of the loire, near nantes, as far as a district south of tours. they are also found at pontlevoy, on the cher, about miles above the junction of that river with the loire, and miles s.e. of tours. i have visited all the localities above mentioned, and found the beds to consist principally of sand and marl, in which are shells and corals, some entire, some rolled, and others in minute fragments. in certain districts, as at doué, in the department of maine and loire, miles s.w. of saumur, they form a soft building-stone, chiefly composed of an aggregate of broken shells, corals, and echinoderms, united by a calcareous cement; the whole mass being very like the coralline crag near aldborough and sudbourn in suffolk. the scattered patches of faluns are of slight thickness, rarely exceeding feet; and between the district called sologne and the sea they repose on a great variety of older rocks; being seen to rest successively upon gneiss, clay-slate, and various secondary formations, including the chalk; and, lastly, upon the upper freshwater limestone of the parisian tertiary series, which, as before mentioned (p. .), stretches continuously from the basin of the seine to that of the loire. at some points, as at louans, south of tours, the shells are stained of a ferruginous colour, not unlike that of the red crag of suffolk. the species are, for the most part, marine, but a few of them belong to land and fluviatile genera. among the former, _helix turonensis_ (fig. . p. .) is the most abundant. remains of terrestrial quadrupeds are here and there intermixed, belonging to the genera deinotherium, mastodon, rhinoceros, hippopotamus, chæropotamus, dichobune, deer, and others, and these are accompanied by cetacea, such as the lamantine, morse, sea-calf, and dolphin, all of extinct species. professor e. forbes, after studying the fossil testacea which i obtained from these beds; informs me that he has no doubt they were formed partly on the shore itself at the level of low water, and partly at very moderate depths, not exceeding fathoms below that level. the molluscous fauna of the "faluns" is on the whole much more littoral than that of the red and coralline crag of suffolk, and implies a shallower sea. it is, moreover, contrasted with the suffolk crag by the indications it affords of an extra-european climate. thus it contains seven species of _cypræa_, some larger than any existing cowry of the mediterranean, several species of _oliva_, _ancillaria_, _mitra_, _terebra_, _pyrula_, _fasciolaria_, and _conus_. of the cones there are no less than eight species, some very large, whereas the only european cone is of diminutive size. the genus _nerita_, and many others, are also represented by individuals of a type now characteristic of equatorial seas, and wholly unlike any mediterranean forms. these proofs of a more elevated temperature seem to imply the higher antiquity of the faluns as compared with the suffolk crag, and are in perfect accordance with the fact of the smaller proportion of testacea of recent species found in the faluns. out of species of shells, collected by myself, in , at pontlevoy, louans, bossée, and other villages miles south of tours; and at savigné, about miles north-west of that place; only could be identified with recent species, which is in the proportion of per cent. a large number of the species are common to all the localities, those peculiar to each not being more numerous than we might expect to find in different bays of the same sea. the total number of mollusca from the faluns, in my possession, is , of which only were found by mr. wood to be common to the suffolk crag. the number of corals obtained by me at doué, and other localities before adverted to, amounts to , as determined by mr. lonsdale, of which agree specifically with those of the suffolk crag. only one has, as yet, been identified with a living species. but it is difficult, if not impossible, to institute at present a satisfactory comparison between fossil and recent _polyparia_, from the deficiency of our knowledge of the living species. some of the genera occurring fossil in touraine, as the _astrea_, _lunulites_, and _dendrophyllia_, have not been found in european seas north of the mediterranean; nevertheless the _polyparia_ of the faluns do not seem to indicate on the whole so warm a climate as would be inferred from the shells. it was stated that, on comparing about species of touraine shells with about from the suffolk crag, only were found to be common to both, which is in the proportion of only per cent. the same small amount of agreement is found in the corals also. i formerly endeavoured to reconcile this marked difference in species with the supposed co-existence of the two faunas, by imagining them to have severally belonged to distinct zoological provinces or two seas, the one opening to the north, and the other to the south, with a barrier of land between them, like the isthmus of suez, separating the red sea and the mediterranean. but i now abandon that idea for several reasons; among others, because i succeeded in in tracing the crag fauna southwards in normandy to within miles of the falunian type, near dinan, yet found that both assemblages of fossils retained their distinctive characters, showing no signs of any blending of species or transition of climate. on a comparison of mediterranean shells with british species, made for me by an experienced conchologist in , were found to be common to both collections, which is in the proportion of per cent., a fourfold greater specific resemblance than between the seas of the crag and the faluns, notwithstanding the greater geographical distance between england and the mediterranean than between suffolk and the loire. the principal grounds, however, for referring the english crag to the older pliocene and the french faluns to the miocene epochs, consist in the predominance of fossil shells in the british strata identifiable with species, not only still living, but which are now inhabitants of neighbouring seas, while the accompanying extinct species are of genera such as characterize europe. in the faluns, on the contrary, the recent species are in a decided minority, and many of them, like the associated extinct testacea, are much less european in character, and point to the prevalence of a warmer climate,--in other words, to a state of things receding farther from the present condition of europe, geographically and climatologically, and doubtless, therefore, receding farther in time. _bordeaux._--a great extent of country between the pyrenees and the gironde is overspread by tertiary deposits, which have been more particularly studied in the environs of bordeaux and dax, from whence about species of shells have been obtained. a large proportion of these shells belong to the same zoological type as those of touraine; but many are peculiar, and the whole may possibly constitute a somewhat older division of the miocene period than the faluns of the loire. we must wait, however, for farther investigations, in order to decide this question with accuracy. _piedmont._--many of the shells peculiar to the hill of the superga, near turin, agree with those found at bordeaux and dax; but the proportion of recent species is much less. the strata of the superga consist of a bright green sand and marl, and a conglomerate with pebbles, chiefly of green serpentine, and are inclined at an angle of more than °. this formation, which attains a great thickness in the valley of the bormida, is probably one of the oldest miocene groups hitherto discovered. _molasse of switzerland._--if we cross the alps, and pass from piedmont to savoy, we find there, at the northern base of the great chain, and throughout the lower country of switzerland, a soft green sandstone much resembling some of the beds of the basin of the bormida, above described, and associated in a similar manner with marls and conglomerate. this formation is called in switzerland "molasse," said to be derived from "mol," "_soft_" because the stone is easily cut in the quarry. it is of vast thickness, and probably divisible into several formations. how large a portion of these belong to the miocene period cannot yet be determined, as fossil shells are often entirely wanting. in some places a decided agreement of the fossil fishes of the molasse and faluns has been observed. among those common to both, m. agassiz pointed out to me _lamna contortidens_, _myliobates studeri_, _spherodus cinctus_, _notidanus primigenius_, and others. _lisbon._--marine tertiary strata near lisbon contain shells which agree very closely with those of bordeaux, and are therefore referred to the miocene era. thus, out of species collected by mr. smith of jordanhill, between and were found to be common to the strata of bordeaux and dax, the recent species being in the proportion of per cent. _older pliocene and miocene formations in the united states._--between the alleghany mountains, formed of older rocks, and the atlantic, there intervenes, in the united states, a low region occupied principally by beds of marl, clay, and sand, consisting of the cretaceous and tertiary formations, and chiefly of the latter. the general elevation of this plain bordering the atlantic does not exceed feet, although it is sometimes several hundred feet high. its width in the middle and southern states is very commonly from to miles. it consists, in the south, as in georgia, alabama, and south carolina, almost exclusively of eocene deposits; but in north carolina, maryland, virginia, and delaware, more modern strata predominate, which i have assimilated in age to the english crag and faluns of touraine.[ -a] if, chronologically speaking, they can be truly said to be the representatives of these two european formations, they may range in age from the older pliocene to the miocene epoch, according to the classification of european strata adopted in this chapter. the proportion of fossil shells agreeing with recent, out of species collected by me, amounted to about per cent., or one-sixth of the whole; but as the fossils so assimilated were almost always the same as species now living in the neighbouring atlantic, the number may hereafter be augmented, when the recent fauna of that ocean is better known. in different localities, also, the proportion of recent species varied considerably. [illustration: fig. . _fulgur canaliculatus._ maryland.] [illustration: fig. . _fusus quadricostatus_, say. maryland.] on the banks of the james river, in virginia, about miles below richmond, in a cliff about feet high, i observed yellow and white sands overlying an eocene marl, just as the yellow sands of the crag lie on the blue london clay in suffolk and essex in england. in the virginian sands, we find a profusion of an astarte (_a. undulata_, conrad), which resembles closely, and may possibly be a variety of, one of the commonest fossils of the suffolk crag (_a. bipartita_); the other shells also, of the genera _natica_, _fissurella_, _artemis_, _lucina_, _chama_, _pectunculus_, and _pecten_, are analogous to shells both of the english crag and french faluns, although the species are almost all distinct. out of of these american fossils i could only find species common to europe, and these occur partly in the suffolk crag, and partly in the faluns of touraine; but it is an important characteristic of the american group, that it not only contains many peculiar extinct forms, such as _fusus quadricostatus_, say (see fig. .), and _venus tridacnoides_, abundant in these same formations, but also some shells which, like _fulgur carica_ of say, and _f. canaliculatus_ (see fig. .), _calyptræa costata_, _venus mercenaria_, lam., _modiola glandula_, totten, and _pecten magellanicus_, lam., are recent species, yet of forms now confined to the western side of the atlantic, a fact implying that the beginning of the present geographical distribution of mollusca dates back to a period as remote as that of the miocene strata. of ten species of zoophytes which i procured on the banks of the james river, two were identical with species of the faluns of touraine. with respect to climate, mr. lonsdale regards these corals as indicating a temperature exceeding that of the mediterranean, and the shells would lead to similar conclusions. those occurring on the james river are in the th degree of n. latitude, while the french faluns are in the th; yet the forms of the american fossils would scarcely imply so warm a climate as must have prevailed in france, when the miocene strata of touraine originated. among the remains of fish in these post-eocene strata of the united states are several large teeth of the shark family, not distinguishable specifically from fossils of the faluns of touraine, and the maltese tertiaries. _india._--the freshwater deposits of the sub-himalayan or sewâlik hills, described by dr. falconer and captain cautley, may perhaps be regarded as miocene. like the faluns of touraine, they contain the deinotherium and mastodon. whether any of the associated freshwater and land shells are of recent species is not yet determined. the occurrence in them of a fossil giraffe and hippopotamus, genera now only living in africa, as well as of a camel, implies a geographical state of things very different from that now established in the same parts of india. the huge sivatherium of the same era appears to have been a ruminating quadruped bigger than the rhinoceros, and provided with a large upper lip, or probably a short proboscis, and having two pair of horns, resembling those of antelopes. several species of monkey belonged to the same fauna; and among the reptiles, several crocodiles, larger than any now living, and an enormous tortoise, _testudo atlas_, the curved shell of which measured feet across. footnotes: [ -a] see paper by e. charlesworth, esq.; london and ed. phil. mag. no. xxxviii. p. ., aug. . [ -b] see monograph on the crag mollusca. searles wood, paleont. soc. . [ -a] in regarding the suffolk crag, both red and coralline, as older pliocene instead of miocene, i am only returning to the classification adopted by me in the principles and elements of geology up to the year . [ -a] e. forbes, mem. geol. survey, gt. brit., vol. i. . [ -a] proceedings of the geol. soc. vol. iv. part . , p. . chapter xv. upper eocene formations. eocene areas in england and france--tabular view of french eocene strata--upper eocene group of the paris basin--same beds in belgium and at berlin--mayence tertiary strata--freshwater upper eocene of central france--series of geographical changes since the land emerged in auvergne--mineral character an uncertain test of age--marls containing cypris--oolite of eocene period--indusial limestone and its origin--fossil mammalia of the upper eocene strata in auvergne--freshwater strata of the cantal, calcareous and siliceous--its resemblance to chalk--proofs of gradual deposition of strata. [illustration: fig. . map of the principal tertiary basins of the eocene period. n. b. the space left blank is occupied by secondary formations from the devonian or old red sandstone to the chalk inclusive.] the tertiary strata described in the preceding chapters are all of them characterized by fossil shells, of which a considerable proportion are specifically identical with the living mollusca; and the greater the number, the more nearly does the entire fauna approach in species and genera to that now inhabiting the adjoining seas. but in the eocene formations next to be considered, the proportion of recent species is very small, and sometimes scarcely appreciable, and those agreeing with the fossil testacea often belong to remote parts of the globe, and to various zoological provinces. this difference in conchological character implies a considerable interval of time between the eocene and miocene periods, during which the whole fauna and flora underwent other changes as great, and often greater, than those exhibited by the mollusca. in the accompanying map, the position of several eocene areas is pointed out, such as the basin of the thames, part of hampshire, part of the netherlands, and the country round paris. the deposits, however, occupying these spaces comprise a great succession of marine and freshwater formations, which, although they may all be termed eocene, as being newer than the chalk, and older than the faluns, are nevertheless divisible into separate groups, of high geological importance. the newest of these, like the faluns of the loire, have no true representatives, or exact chronological equivalents, in the british isles. their place in the series will best be understood by referring to the order of superposition of the successive deposits found in the neighbourhood of paris. the area which has been called the paris basin is about miles in its greatest length from north-east to south-west, and about miles from east to west. this space may be described as a depression in the chalk, which has been filled up by alternating groups of marine and freshwater strata. mm. cuvier and brongniart attempted, in , to distinguish five different formations, comprising three freshwater and two marine, which alternated with each other. it was imagined that the waters of the ocean had been by turns admitted and excluded from the same region; but the subsequent investigations of several geologists, especially of m. constant prevost,[ -a] have led to great modifications in these theoretical views; and now that the true order of succession is better understood, it appears that several of the deposits, which were supposed to have originated one after the other, were, in fact, in progress at the same time by the joint action of the sea and rivers. the whole series of strata may be divided into three groups, as expressed in the following table:-- { _a._ upper freshwater limestone, marls, and siliceous . upper eocene { millstone. { _b._ upper marine sands, or fontainebleau sandstone { and sand. { _a._ lower freshwater limestone and marl, or { gypseous series. { _b._ sandstone and sands with marine shells (_sables_ . middle eocene { _moyens_, or _grès de beauchamp_). { _c._ calcaire grossier, limestone with marine shells. { _d._ calcaire siliceux, hard siliceous freshwater { limestone, for the most part contemporaneous { with _c_. { _a._ lower sands with marine shelly beds (_sables_ . lower eocene { _inférieurs et lits coquilliers_). { _b._ lower sands, with lignite and plastic clay { (_sables inférieurs et argiles plastiques_). postponing to the next chapter the consideration of the middle and lower eocene groups, i shall now speak of the upper eocene of paris, and its foreign equivalents. the upper freshwater marls and limestone ( . _a_) seem to have been formed in a great number of marshes and shallow lakes, such as frequently overspread the newest parts of great deltas. it appears that many layers of marl, tufaceous limestone, and travertin, with beds of flint, continuous or in nodules, accumulated in these lakes. _charæ_, aquatic plants, already alluded to (see p. .) left their stems and seed-vessels imbedded both in the marl and flint, together with freshwater and land shells. some of the siliceous rocks of this formation are used extensively for millstones. the flat summits or platforms of the hills round paris, large areas in the forest of fontainebleau, and the plateau de la beauce, between the seine and the loire, are chiefly composed of these upper freshwater strata. the upper marine sands ( . _b_), consist chiefly of micaceous and quartzose sands, feet thick. as they succeed throughout an extensive area deposit of a purely freshwater origin ( _a_.), they appear to mark a subsidence of the subjacent soil, whether it had formed the bottom of an estuary or a lake. the sea, which afterwards took possession of the same space, was inhabited by testacea, almost all of them differing from those found in the lower formations ( . _b_ and . _c_) and equally or still more distinct from the miocene faluns of subsequent date. one of these upper eocene strata in the neighbourhood of paris has been called the oyster bed, "couche à _ostrea cyathula_, lamk.," which is spread over a remarkably wide area. from the manner in which the oysters lie, it is inferred that they did not grow on the spot, but that some current swept them away from a bed of oysters formed in some other part of the bay. the strata of sand which immediately repose on the oyster-bed are quite destitute of organic remains; and nothing is more common in the paris basin, and in other formations, than alternations of shelly beds with others entirely devoid of them. the temporary extinction and renewal of animal life at successive periods have been rashly inferred from such phenomena, which may nevertheless be explained, as m. prevost justly remarks, without appealing to any such extraordinary revolutions in the state of the animate creation. a current one day scoops out a channel in a bed of shelly sand and mud, and the next day, by a slight alteration of its course, ceases to prey upon the same bank. it may then become charged with sand unmixed with shells, derived from some dune, or brought down by a river. in the course of ages an indefinite number of transitions from shelly strata to those without shells may thus be caused. besides these oysters, m. deshayes has described species of shells, in his work (coquilles fossiles de paris), as belonging to this formation, all save one regarded by him as differing from fossils of the calcaire grossier. since that time the railway cuttings near etampes have enabled m. hébert to raise the number to . i have myself collected fossils in that district, where the shells are very entire, and detachable from the yellow sandy matrix. m. hébert first pointed out that most of them agree specifically with those of kleyn spauwen, boom, and other localities of limburg in flanders, where they have been studied by mm. nyst and de koninck.[ -a] the position in belgium of this formation above the older eocene group is well seen in the small hill of pellenberg, rising abruptly from the great plain, half a mile south-east of the city of louvain, where i examined it in company with m. nyst in . at the top of the hill, a thin bed of dark greyish green tile-clay is seen - / foot thick, with casts of _nucula deshaysiana_. this clay rests on feet of yellow sand, separated, by a band of flint and quartz pebbles, from a mass of subjacent white sand feet thick, in which casts of the kleyn spauwen fossils have been met with. under this is a bed of yellow sand feet thick, and, at a lower level, the railway cuttings have passed through calcareous sands like those of brussels, in which the _nautilus burtini_, and various shells common to the older eocene strata of the neighbourhood of london, have been obtained. every new fact which throws light on the true paleontological relations of the strata now under consideration, (the upper marine or fontainebleau beds of the paris basin, . _b_, p. .), deserves more particular attention, because geologists of high authority differ in opinion as to whether they should be classed as eocene or miocene. professor beyrich has lately described a formation of the same age, occurring within miles of the gates of berlin, near the village of hermsdorf, where, in the midst of the sands of which that country chiefly consists, a mass of tile-clay, more than feet thick, and of a dark blueish grey colour, is found, full of shells, among which the genera _fusus_ and _pleurotoma_ predominate, and among the bivalves, _nucula deshaysiana_, nyst, an extremely common shell in the belgian beds above-mentioned. m. beyrich has identified eighteen out of forty-five species of the hermsdorf fossils with the belgian species; and i believe that a much larger proportion agree with the upper eocene of belgium, france, and the rhine. on the other hand, eight of the forty-five species are supposed by him to agree with english eocene shells. messrs. morris, edwards, and s. wood have compared a small collection, which i obtained of these berlin shells, with the eocene fossils of their museums, and confirmed the result of m. beyrich, the species common to the english fossils belonging not simply to the uppermost of our marine beds, or those of barton, but some of them to lower parts of the series, such as bracklesham and highgate. on the other hand, while these testacea, like those of kleyn spauwen and etampes, present many analogies to the middle and lower eocene group, they differ widely from the falun shells,--a fact the more important in reference to etampes, as that locality approaches within miles of pontlevoy, near blois, and within miles of savigné, near tours, where falun shells are found. it is evident that the discordance of species cannot be attributed to distance or geographical causes, but must be referred to time, or the different epoch at which the upper marine beds of the paris basin and the faluns of the loire originated. _mayence._--the true chronological relation of many tertiary strata on the banks of the rhine has always presented a problem of considerable difficulty. they occupy a tract from to miles in breadth, extending along the left bank of the rhine from mayence to the neighbourhood of manheim, and are again found to the east, north, and south-west of frankfort. in some places they have the appearance of a freshwater formation; but in others, as at alzey, the shells are for the most part marine. _cerithia_ are in great profusion, which indicates that the sea where the deposit was formed was fed by rivers; and the great quantity of fossil land shells, chiefly of the genus _helix_, confirm the same opinion. the variety in the species of shells is small, while the individuals are exceedingly numerous; a fact which accords perfectly with the idea that the formation may have originated in a gulf or sea which, like the baltic, was brackish in some parts, and almost fresh in others. a species of _paludina_ (fig. .), very nearly resembling the recent _littorina ulva_, is found throughout this basin. these shells are like grains of rice in size, and are often in such quantity as to form entire beds of marl and limestone. they are as thick as grains of sand, in stratified masses from to feet in thickness. [illustration: fig. . _paludina._ mayence.] that these rhenish tertiary formations agree more nearly with the upper eocene deposits above enumerated, than with any others, i have no doubt, since i had the advantage of comparing (august, ), with the assistance of m. de koninck of liége, the fossils from kleyn spauwen, boom, and other limburg localities, with those from mayence, alzey, weinheim, and other rhenish strata. among the common belgian and rhenish shells which are identical, i may mention _cassidaria depressa_, _tritonium flandricum_ de koninck, _cerithium tricinctum_ nyst, _tornatella simulata_, _rostellaria sowerbyi_, _nucula deshaysiana_, _corbula pisum_, and _pectunculus terebratularis_. from these upper eocene deposits of the rhine m. h. von meyer has obtained a great number of characteristic fossil mammalia, such as _palæomæryx medius_, _hyotherium meissneri_, _tapirus helveticus_, _anthracotherium alsaticum_, and others. the three first of these are species common to some of the lignite, or brown coal beds in switzerland, commonly classed with the molasse, but of which the true age has not yet been distinctly made out. the fossils of the sandy beds of eppelsheim, comprising bones of the deinotherium, mastodon, and other quadrupeds, are regarded by h. von meyer as belonging to a mammiferous fauna quite distinct from that of the mayence basin, and they are probably referable to the miocene period. the upper freshwater strata ( . _a_, p. .), of the neighbourhood of paris, stretch southwards from the valley of the seine to that of the loire, and in the last-mentioned region are seen to be older than the marine faluns, so that the perforating shells of the miocene sea have sometimes bored the hard compact freshwater limestones; and fragments of the upper eocene rocks are found at pontlevoy and elsewhere, which have been rolled in the bed of the miocene sea. [illustration: fig. . simplified geological map south of paris.] _central france._--lacustrine strata belonging, for the most part, to the same upper eocene series, are again met with in auvergne, cantal, and velay, the sites of which may be seen in the annexed map. they appear to be the monuments of ancient lakes, which, like some of those now existing in switzerland, once occupied the depressions in a mountainous region, and have been each fed by one or more rivers and torrents. the country where they occur is almost entirely composed of granite and different varieties of granitic schist, with here and there a few patches of secondary strata, much dislocated, and which have probably suffered great denudation. there are also some vast piles of volcanic matter (see the map), the greater part of which is newer than the freshwater strata, and is sometimes seen to rest upon them, while a small part has evidently been of contemporaneous origin. of these igneous rocks i shall treat more particularly in another part of this work. before entering upon any details, i may observe, that the study of these regions possesses a peculiar interest, very distinct in kind from that derivable from the investigation either of the parisian or english tertiary strata. for we are presented in auvergne with the evidence of a series of events of astonishing magnitude and grandeur, by which the original form and features of the country have been greatly changed, yet never so far obliterated but that they may still, in part at least, be restored in imagination. great lakes have disappeared,--lofty mountains have been formed, by the reiterated emission of lava, preceded and followed by showers of sand and scoriæ,--deep valleys have been subsequently furrowed out through masses of lacustrine and volcanic origin,--at a still later date, new cones have been thrown up in these valleys,--new lakes have been formed by the damming up of rivers,--and more than one creation of quadrupeds, birds, and plants, eocene, miocene, and pliocene, have followed in succession; yet the region has preserved from first to last its geographical identity; and we can still recall to our thoughts its external condition and physical structure before these wonderful vicissitudes began, or while a part only of the whole had been completed. there was first a period when the spacious lakes, of which we still may trace the boundaries, lay at the foot of mountains of moderate elevation, unbroken by the bold peaks and precipices of mont dor, and unadorned by the picturesque outline of the puy de dome, or of the volcanic cones and craters now covering the granitic platform. during this earlier scene of repose deltas were slowly formed; beds of marl and sand, several hundred feet thick, deposited; siliceous and calcareous rocks precipitated from the waters of mineral springs; shells and insects imbedded, together with the remains of the crocodile and tortoise, the eggs and bones of water birds, and the skeletons of quadrupeds, some of them belonging to the same genera as those entombed in the eocene gypsum of paris. to this tranquil condition of the surface succeeded the era of volcanic eruptions, when the lakes were drained, and when the fertility of the mountainous district was probably enhanced by the igneous matter ejected from below, and poured down upon the more sterile granite. during these eruptions, which appear to have taken place after the disappearance of the eocene fauna, and in the miocene epoch, the mastodon, rhinoceros, elephant, tapir, hippopotamus, together with the ox, various kinds of deer, the bear, hyæna, and many beasts of prey, ranged the forest, or pastured on the plain, and were occasionally overtaken by a fall of burning cinders, or buried in flows of mud, such as accompany volcanic eruptions. lastly, these quadrupeds became extinct, and gave place to pliocene mammalia, and these, in their turn, to species now existing. there are no signs, during the whole time required for this series of events, of the sea having intervened, nor of any denudation which may not have been accomplished by currents in the different lakes, or by rivers and floods accompanying repeated earthquakes, during which the levels of the district have in some places been materially modified, and perhaps the whole upraised relatively to the surrounding parts of france. _auvergne._--the most northern of the freshwater groups is situated in the valley-plain of the allier, which lies within the department of the puy de dome, being the tract which went formerly by the name of the limagne d'auvergne. it is inclosed by two parallel mountain ranges,--that of the forèz, which divides the waters of the loire and allier, on the east; and that of the monts domes, which separates the allier from the sioule, on the west.[ -a] the average breadth of this tract is about miles; and it is for the most part composed of nearly horizontal strata of sand, sandstone, calcareous marl, clay, and limestone, none of which observe a fixed and invariable order of superposition. the ancient borders of the lake, wherein the freshwater strata were accumulated, may generally be traced with precision, the granite and other ancient rocks rising up boldly from the level country. the actual junction, however, of the lacustrine and granitic beds is rarely seen, as a small valley usually intervenes between them. the freshwater strata may sometimes be seen to retain their horizontality within a very slight distance of the border-rocks, while in some places they are inclined, and in few instances vertical. the principal divisions into which the lacustrine series may be separated are the following:-- st, sandstone, grit, and conglomerate, including red marl and red sandstone. dly, green and white foliated marls. dly, limestone or travertin, often oolitic. thly, gypseous marls. . _a_. _sandstone and conglomerate._--strata of sand and gravel, sometimes bound together into a solid rock, are found in great abundance around the confines of the lacustrine basin, containing, in different places, pebbles of all the ancient rocks of the adjoining elevated country; namely, granite, gneiss, mica-schist, clay-slate, porphyry, and others. but these strata do not form one continuous band around the margin of the basin, being rather disposed like the independent deltas which grow at the mouths of torrents along the borders of existing lakes. at chamalieres, near clermont, we have an example of one of these deltas, or littoral deposits, of local extent, where the pebbly beds slope away from the granite, as if they had formed a talus beneath the waters of the lake near the steep shore. a section of about feet in vertical height has been laid open by a torrent, and the pebbles are seen to consist throughout of rounded and angular fragments of granite, quartz, primary slate, and red sandstone; but without any intermixture of those volcanic rocks which now abound in the neighbourhood, and which could not have been there when the conglomerate was formed. partial layers of lignite and pieces of wood are found in these beds. at some localities on the margin of the basin quartzose grits are found; and, where these rest on granite, they are sometimes formed of separate crystals of quartz, mica, and felspar, derived from the disintegrated granite, the crystals having been subsequently bound together by a siliceous cement. in these cases the granite seems regenerated in a new and more solid form; and so gradual a passage takes place between the rock of crystalline and that of mechanical origin, that we can scarcely distinguish where one ends and the other begins. in the hills called the puy de jussat and la roche, we have the advantage of seeing a section continuously exposed for about feet in thickness. at the bottom are foliated marls, white and green, about feet thick; and above, resting on the marls, are the quartzose grits, cemented by calcareous matter, which is sometimes so abundant as to form imbedded nodules. these sometimes constitute spheroidal concretions feet in diameter, and pass into beds of solid limestone, resembling the italian travertins, or the deposits of mineral springs. this section is close to the confines of the basin; so that the lake must here have been filled up near the shore with fine mud, before the coarse superincumbent sand was introduced. there are other cases where sand is seen below the marl. . _b._ _red marl and sandstone_.--but the most remarkable of the arenaceous groups is one of red sandstone and red marl, which are identical in all their mineral characters with the secondary _new red sandstone_ and marl of england. in these secondary rocks the red ground is sometimes variegated with light greenish spots, and the same may be seen in the tertiary formation of freshwater origin at coudes, on the allier. the marls are sometimes of a purplish-red colour, as at champheix, and are accompanied by a reddish limestone, like the well-known "cornstone," which is associated with the old red sandstone of english geologists. the red sandstone and marl of auvergne have evidently been derived from the degradation of gneiss and mica-schist, which are seen _in situ_ on the adjoining hills, decomposing into a soil very similar to the tertiary red sand and marl. we also find pebbles of gneiss, mica-schist, and quartz in the coarser sandstones of this group, clearly pointing to the parent rocks from which the sand and marl are derived. the red beds, although destitute themselves of organic remains, pass upwards into strata containing eocene fossils, and are certainly an integral part of the lacustrine formation. from this example the student will learn how small is the value of mineral character alone, as a test of the relative age of rocks. . _green and white foliated marls._--the same primary rocks of auvergne, which, by the partial degradation of their harder parts, gave rise to the quartzose grits and conglomerates before mentioned, would, by the reduction of the same materials into powder, and by the decomposition of their felspar, mica, and hornblende, produce aluminous clay, and, if a sufficient quantity of carbonate of lime was present, calcareous marl. this fine sediment would naturally be carried out to a greater distance from the shore, as are the various finer marls now deposited in lake superior. and, as in the american lake, shingle and sand are annually amassed near the northern shores, so in auvergne the grits and conglomerates before mentioned were evidently formed near the borders. [illustration: fig. . _cypris unifasciata_, a living species, greatly magnified. _a._ upper part. _b._ side view of the same.] [illustration: fig. . _cypris vidua_, a living species, greatly magnified.[ -a]] the entire thickness of these marls is unknown; but it certainly exceeds, in some places, feet. they are, for the most part, either light-green or white, and usually calcareous. they are thinly foliated,--a character which frequently arises from the innumerable thin shells, or carapace-valves, of that small animal called _cypris_; a genus which comprises several species, of which some are recent, and may be seen swimming swiftly through the waters of our stagnant pools and ditches. the antennæ, at the end of which are fine pencils of hair, are the principal organs of motion, and are seen to vibrate with great rapidity. this animal resides within two small valves, not unlike those of a bivalve shell, and moults its integuments periodically, which the conchiferous mollusks do not. this circumstance may partly explain the countless myriads of the shells of _cypris_ which were shed in the ancient lakes of auvergne, so as to give rise to divisions in the marl as thin as paper, and that, too, in stratified masses several hundred feet thick. a more convincing proof of the tranquillity and clearness of the waters, and of the slow and gradual process by which the lake was filled up with fine mud, cannot be desired. but we may easily suppose that, while this fine sediment was thrown down in the deep and central parts of the basin, gravel, sand, and rocky fragments were hurried into the lake, and deposited near the shore, forming the group described in the preceding section. not far from clermont, the green marls, containing the _cypris_ in abundance, approach to within a few yards of the granite which forms the borders of the basin. the occurrence of these marls so near the ancient margin may be explained by considering that, at the bottom of the ancient lake, no coarse ingredients were deposited in spaces intermediate between the points where rivers and torrents entered, but finer mud only was drifted there by currents. the _verticality_ of some of the beds in the above section bears testimony to considerable local disturbance subsequent to the deposition of the marls; but such inclined and vertical strata are very rare. [illustration: fig. . vertical strata of marl, at champradelle, near clermont. a. granite. b. space of feet, in which no section is seen. c. green marl, vertical and inclined. d. white marl.] . _limestone, travertin, oolite._--both the preceding members of the lacustrine deposit, the marls and grits, pass occasionally into limestone. sometimes only concretionary nodules abound in them; but these, where there is an increase in the quantity of calcareous matter, unite into regular beds. on each side of the basin of the limagne, both on the west at gannat, and on the east at vichy, a white oolitic limestone is quarried. at vichy, the oolite resembles our bath stone in appearance and beauty; and, like it, is soft when first taken from the quarry, but soon hardens on exposure to the air. at gannat, the stone contains land-shells and bones of quadrupeds, resembling those of the paris gypsum. at chadrat, in the hill of la serre, the limestone is pisolitic, the small spheroids combining both the radiated and concentric structure. _indusial limestone._--there is another remarkable form of freshwater limestone in auvergne, called "indusial," from the cases, or _indusiæ_, of caddis-worms (the larvæ of _phryganea_); great heaps of which have been incrusted, as they lay, by carbonate of lime, and formed into a hard travertin. the rock is sometimes purely calcareous, but there is occasionally an intermixture of siliceous matter. several beds of it are frequently seen, either in continuous masses, or in concretionary nodules, one upon another, with layers of marl interposed. the annexed drawing (fig. .) will show the manner in which one of these indusial beds (_a_) is laid open at the surface, between the marls (_b b_), near the base of the hill of gergovia; and affords, at the same time, an example of the extent to which the lacustrine strata, which must once have filled a hollow, have been denuded, and shaped out into hills and valleys, on the site of the ancient lakes. [illustration: fig. . bed of indusial limestone, interstratified with freshwater marl, near clermont (kleinschrod.)] [illustration: fig. . larva of recent phryganea.[ -a]] [illustration: fig. . _a_. indusial limestone of auvergne. _b_. fossil _paludina_ magnified.] we may often observe in our ponds the _phryganea_ (or caddis-fly), in its caterpillar state, covered with small freshwater shells, which they have the power of fixing to the outside of their tubular cases, in order, probably, to give them weight and strength. the individual figured in the annexed cut, which belongs to a species very abundant in england, has covered its case with shells of a small _planorbis_. in the same manner a large species of caddis-worm, which swarmed in the eocene lakes of auvergne, was accustomed to attach to its dwelling the shells of a small spiral univalve of the genus _paludina_. a hundred of these minute shells are sometimes seen arranged around one tube, part of the central cavity of which is often empty, the rest being filled up with thin concentric layers of travertin. the cases have been thrown together confusedly, and often lie, as in fig. ., at right angles one to the other. when we consider that ten or twelve tubes are packed within the compass of a cubic inch, and that some single strata of this limestone are feet thick, and may be traced over a considerable area, we may form some idea of the countless number of insects and mollusca which contributed their integuments and shells to compose this singularly constructed rock. it is unnecessary to suppose that the _phryganeæ_ lived on the spots where their cases are now found; they may have multiplied in the shallows near the margin of the lake, or in the streams by which it was fed, and their cases may have been drifted by a current far into the deep water. in the summer of , when examining, in company with dr. beck, a small lake near copenhagen, i had an opportunity of witnessing a beautiful exemplification of the manner in which the tubular cases of auvergne were probably accumulated. this lake, called the fuure-soe, occurring in the interior of seeland, is about twenty english miles in circumference, and in some parts feet in depth. round the shallow borders an abundant crop of reeds and rushes may be observed, covered with the indusiæ of the _phryganea grandis_ and other species, to which shells are attached. the plants which support them are the bullrush, _scirpus lacustris_, and common reed, _arundo phragmitis_, but chiefly the former. in summer, especially in the month of june, a violent gust of wind sometimes causes a current by which these plants are torn up by the roots, washed away, and floated off in long bands, more than a mile in length, into deep water. the _cypris_ swarms in the same lake; and calcareous springs alone are wanting to form extensive beds of indusial limestone, like those of auvergne. . _gypseous marls._--more than feet of thinly laminated gypseous marls, exactly resembling those in the hill of montmartre, at paris, are worked for gypsum at st. romain, on the right bank of the allier. they rest on a series of green cypriferous marls which alternate with grit, the united thickness of this inferior group being seen, in a vertical section on the banks of the river, to exceed feet. _general arrangement, origin, and age of the freshwater formations of auvergne._--the relations of the different groups above described cannot be learnt by the study of any one section; and the geologist who sets out with the expectation of finding a fixed order of succession may perhaps complain that the different parts of the basin give contradictory results. the arenaceous division, the marls, and the limestone, may all be seen in some places to alternate with each other; yet it can, by no means, be affirmed that there is no order of arrangement. the sands, sandstone, and conglomerate, constitute in general a littoral group; the foliated white and green marls, a contemporaneous central deposit; and the limestone is for the most part subordinate to the newer portions of both. the uppermost marls and sands are more calcareous than the lower; and we never meet with calcareous rocks covered by a considerable thickness of quartzose sand or green marl. from the resemblance of the limestones to the italian travertins, we may conclude that they were derived from the waters of mineral springs,--such springs as even now exist in auvergne, and which may be seen rising up through the granite, and precipitating travertin. they are sometimes thermal, but this character is by no means constant. it seems that, when the ancient lake of the limagne first began to be filled with sediment, no volcanic action had yet produced lava and scoriæ on any part of the surface of auvergne. no pebbles, therefore, of lava were transported into the lake,--no fragments of volcanic rocks embedded in the conglomerate. but at a later period, when a considerable thickness of sandstone and marl had accumulated, eruptions broke out, and lava and tuff were deposited, at some spots, alternately with the lacustrine strata. it is not improbable that cold and thermal springs, holding different mineral ingredients in solution, became more numerous during the successive convulsions attending this development of volcanic agency, and thus deposits of carbonate and sulphate of lime, silex, and other minerals were produced. hence these minerals predominate in the uppermost strata. the subterranean movements may then have continued until they altered the relative levels of the country, and caused the waters of the lakes to be drained off, and the farther accumulation of regular freshwater strata to cease. we may easily conceive a similar series of events to give rise to analogous results in any modern basin, such as that of lake superior, for example, where numerous rivers and torrents are carrying down the detritus of a chain of mountains into the lake. the transported materials must be arranged according to their size and weight, the coarser near the shore, the finer at a greater distance from land; but in the gravelly and sandy beds of lake superior no pebbles of modern volcanic rocks can be included, since there are none of these at present in the district. if igneous action should break out in that country, and produce lava, scoriæ, and thermal springs, the deposition of gravel, sand, and marl might still continue as before; but, in addition, there would then be an intermixture of volcanic gravel and tuff, and of rocks precipitated from the waters of mineral springs. although the freshwater strata of the limagne approach generally to a horizontal position, the proofs of local disturbance are sufficiently numerous and violent to allow us to suppose great changes of level since the lacustrine period. we are unable to assign a northern barrier to the ancient lake, although we can still trace its limits to the east, west, and south, where they were formed of bold granite eminences. nor need we be surprised at our inability to restore entirely the physical geography of the country after so great a series of volcanic eruptions; for it is by no means improbable that one part of it, the southern, for example, may have been moved upwards bodily, while others remained at rest, or even suffered a movement of depression. whether all the freshwater formations of the limagne d'auvergne belong to one period, i cannot pretend to decide, as large masses both of the arenaceous and marly groups are often devoid of fossils. much light has been thrown on the mammiferous fauna by the labours of mm. bravard and croizet, and by those of m. pomel. the last-mentioned naturalist has pointed out the specific distinction of all, or nearly all, the species of mammalia, from those of the gypseous series near paris. nevertheless, many of the forms are analogous to those of eocene quadrupeds. the _cainotherium_, for example, is not far removed from the _anoplotherium_, and is, according to waterhouse, the same as the genus _microtherium_ of the germans. there are two species of marsupial animals allied to _didelphys_, a genus also found in the paris gypsum. the _amphitragulus elegans_ of pomel, has been identified with a rhenish species from weissenau near mayence, called by kaup _dorcatherium nanum_; and other auvergne fossils, e.g., _microtherium reuggeri_, and a small rodent, _titanomys_, are specifically the same with mammalia of the mayence basin. _cantal._--a freshwater formation, very analogous to that of auvergne, is situated in the department of haute loire, near the town of le puy, in velay, and another occurs near aurillac, in cantal. the leading feature of the formation last mentioned, as distinguished from those of auvergne and velay, is the immense abundance of silex associated with calcareous marls and limestone. the whole series may be separated into two divisions; the lower, composed of gravel, sand, and clay, such as might have been derived from the wearing down and decomposition of the granitic schists of the surrounding country; the upper system, consisting of siliceous and calcareous marls, contains subordinately gypsum, silex, and limestone. the resemblance of the freshwater limestone of the cantal, and its accompanying flint, to the upper chalk of england, is very instructive, and well calculated to put the student upon his guard against relying too implicitly on mineral character alone as a safe criterion of relative age. when we approach aurillac from the west, we pass over great heathy plains, where the sterile mica-schist is barely covered with vegetation. near ytrac, and between la capelle and viscamp, the surface is strewed over with loose broken flints, some of them black in the interior, but with a white external coating; others stained with tints of yellow and red, and in appearance precisely like the flint gravel of our chalk districts. when heaps of this gravel have thus announced our approach to a new formation, we arrive at length at the escarpment of the lacustrine beds. at the bottom of the hill which rises before us, we see strata of clay and sand, resting on mica-schist; and above, in the quarries of belbet, leybros, and bruel, a white limestone, in horizontal strata, the surface of which has been hollowed out into irregular furrows, since filled up with broken flint, marl, and dark vegetable mound. in these cavities we recognize an exact counterpart to those which are so numerous on the furrowed surface of our own white chalk. advancing from these quarries along a road made of the white limestone, which reflects as glaring a light in the sun, as do our roads composed of chalk, we reach, at length, in the neighbourhood of aurillac, hills of limestone and calcareous marl, in horizontal strata, separated in some places by regular layers of flint in nodules, the coating of each nodule being of an opaque white colour, like the exterior of the flinty nodules of our chalk. it will be remembered that the siliceous stone of bilin, called _tripoli_, is a freshwater deposit, and has been shown, by ehrenberg, to be of infusorial origin (see p. .). what is true of the bohemian flint and opal, where the beds attain a thickness of feet, may also, perhaps, be found to hold good respecting the silex of aurillac, which may also have been immediately derived from the minute cases of microscopic animalcules. but even if this conclusion be established, the abundant supply both of siliceous, calcareous, and gypseous matter, which the ancient lakes of france received, may have been connected with the subterranean volcanic agency of which those regions were so long the theatre, and which may have impregnated the springs with mineral matter, even before the great outbreak of lava. it is well known that the hot springs of iceland, and many other countries, contain silex in solution; and it has been lately affirmed, that steam at a high temperature is capable of dissolving quartzose rocks without the aid of any alkaline or other flux.[ -a] travellers not unfrequently mention, in their accounts of india, australia, and other distant lands, that they have seen chalk with flints, which they have assumed to be of the same age as the cretaceous system of europe. a hasty observation of the white limestone and flint of aurillac might convey the same idea; but when we turn from the mineral aspect and composition to the organic remains, we find in the flints of the cantal the seed-vessels of the freshwater _chara_, instead of the marine zoophytes so abundantly imbedded in chalk flints; and in the limestone we meet with shells of _limnea_, _planorbis_, and other lacustrine genera, instead of the oyster, terebratula, and echinus of the cretaceous period. _proofs of gradual deposition_.--some sections of the foliated marls in the valley of the cer, near aurillac, attest, in the most unequivocal manner, the extreme slowness with which the materials of the lacustrine series were amassed. in the hill of barrat, for example, we find an assemblage of calcareous and siliceous marls; in which, for a depth of at least feet, the layers are so thin, that thirty are sometimes contained in the thickness of an inch; and when they are separated, we see preserved in every one of them the flattened stems of _charæ_, or other plants, or sometimes myriads of small _paludinæ_ and other freshwater shells. these minute foliations of the marl resemble precisely some of the recent laminated beds of the scotch marl lakes, and may be compared to the pages of a book, each containing a history of a certain period of the past. the different layers may be grouped together in beds from a foot to a foot and a half in thickness, which are distinguished by differences of composition and colour, the tints being white, green, and brown. occasionally there is a parting layer of pure flint, or of black carbonaceous vegetable matter, about an inch thick, or of white pulverulent marl. we find several hills in the neighbourhood of aurillac composed of such materials, for the height of more than feet from their base, the whole sometimes covered by rocky currents of trachytic or basaltic lava.[ -a] thus wonderfully minute are the separate parts of which some of the most massive geological monuments are made up! when we desire to classify, it is necessary to contemplate entire groups of strata in the aggregate; but if we wish to understand the mode of their formation, and to explain their origin, we must think only of the minute subdivisions of which each mass is composed. we must bear in mind how many thin leaf-like seams of matter, each containing the remains of myriads of testacea and plants, frequently enter into the composition of a single stratum, and how vast a succession of these strata unite to form a single group! we must remember, also, that piles of volcanic matter, like the plomb du cantal, which rises in the immediate neighbourhood of aurillac, are themselves equally the result of successive accumulation, consisting of reiterated sheets of lava, showers of scoriæ, and ejected fragments of rock.--lastly, we must not forget that continents and mountain-chains, colossal as are their dimensions, are nothing more than an assemblage of many such igneous and aqueous groups, formed in succession during an indefinite lapse of ages, and superimposed upon each other. footnotes: [ -a] bulletin des sci. de la soc. philom., may, , p. . [ -a] hébert. bulletin. , vol. vi. d series, p. . [ -a] scrope, geology of central france, p. . [ -a] see desmarest's crustacea, plate . [ -a] i believe that the british specimen here figured is p. _rhombica_, linn. [ -a] see proceedings of roy. soc., no. . p. . [ -a] lyell and murchison, sur les dépôts lacust. tertiaries du cantal, &c. ann. des sci. nat. oct. . chapter xvi. eocene formations--_continued_. subdivisions of the eocene group in the paris basin--gypseous series--extinct quadrupeds--impulse given to geology by cuvier's osteological discoveries--shelly sands called sables moyens--calcaire grossier--miliolites--calcaire siliceux--lower eocene in france--lits coquilliers--sands and plastic clay--english eocene strata--freshwater and fluvio-marine beds--barton beds--bagshot and bracklesham division--large ophidians and saurians--lower eocene and london clay proper--fossil plants and shells--strata of kyson in suffolk--fossil monkey and opossum--mottled clays and sands below london clay--nummulitic formation of alps and pyrenees--its wide geographical extent--eocene strata in the united states--section at claiborne, alabama--colossal cetacean--orbitoid limestone--burr stone. from what was said in the two preceding chapters, it has already appeared that we have in england no true chronological representative of the miocene faluns of the loire, and none of the upper eocene group described in the last chapter. but, when we descend to the middle and inferior divisions of the eocene system of france, we find that they have their equivalents in great britain. middle eocene.--france. _gypseous series_ ( . _a_, table, p. .).--next below the upper marine sands of the neighbourhood of paris, we find a series of white and green marls, with subordinate beds of gypsum. these are most largely developed in the central parts of the paris basin, and, among other places, in the hill of montmartre, where its fossils were first studied by m. cuvier. the gypsum quarried there for the manufacture of plaster of paris occurs as a granular crystalline rock, and, together with the associated marls, contains land and fluviatile shells, together with the bones and skeletons of birds and quadrupeds. several land plants are also met with, among which are fine specimens of the fan palm or palmetto tribe (_flabellaria_). the remains also of freshwater fish and of crocodiles and other reptiles, occur in the gypsum. the skeletons of mammalia are usually isolated, often entire, the most delicate extremities being preserved; as if the carcasses, clothed with their flesh and skin, had been floated down soon after death, and while they were still swoln by the gases generated by their first decomposition. the few accompanying shells are of those light kinds which frequently float on the surface of rivers, together with wood. m. prevost has therefore suggested that a river may have swept away the bodies of animals, and the plants which lived on its borders, or in the lakes which it traversed, and may have carried them down into the centre of the gulf into which flowed the waters impregnated with sulphate of lime. we know that the fiume salso in sicily enters the sea so charged with various salts that the thirsty cattle refuse to drink of it. a stream of sulphureous water, as white as milk, descends into the sea from the volcanic mountain of idienne on the east of java; and a great body of hot water, charged with sulphuric acid, rushed down from the same volcano on one occasion, and inundated a large tract of country, destroying, by its noxious properties, all the vegetation.[ -a] in like manner the pusanibio, or "vinegar river," of colombia, which rises at the foot of puracé, an extinct volcano, , feet above the level of the sea, is strongly impregnated with sulphuric and muriatic acids and with oxide of iron. we may easily suppose the waters of such streams to have properties noxious to marine animals, and in this manner the entire absence of marine remains in the ossiferous gypsum may be explained.[ -b] there are no pebbles or coarse sand in the gypsum; a circumstance which agrees well with the hypothesis that these beds were precipitated from water holding sulphate of lime in solution, and floating the remains of different animals. in this formation the relics of about fifty species of quadrupeds, including the genera _paleotherium_, _anoplotherium_, and others, have been found, all extinct, and nearly four-fifths of them belonging to a division of the order _pachydermata_, which is now represented by only four living species; namely three tapirs and the daman of the cape. with them a few carnivorous animals are associated, among which are a species of fox and gennet. of the _rodentia_, a dormouse and a squirrel; of the _insectivora_, a bat; and of the _marsupialia_ (an order now confined to america, australia, and some contiguous islands), an opossum, have been discovered. of birds, about ten species have been ascertained, the skeletons of some of which are entire. none of them are referable to existing species.[ -a] the same remark applies to the fish, according to mm. cuvier, and agassiz, as also to the reptiles. among the last are crocodiles and tortoises of the genera _emys_ and _trionyx_. the tribe of land quadrupeds most abundant in this formation is such as now inhabits alluvial plains and marshes, and the banks of rivers and lakes, a class most exposed to suffer by river inundations. whether the disproportion of carnivorous animals can be ascribed to this cause, or whether they were comparatively small in number and dimensions, as in the indigenous fauna of australia, when first known to europeans, is a point on which it would be rash, perhaps, to offer an opinion in the present state of our knowledge. [illustration: fig. . _paleotherium magnum._] the paleothere, above alluded to, resembled the living tapir in the form of the head, and in having a short proboscis, but its molar teeth were more like those of the rhinoceros (see fig. .). _paleotherium magnum_ was of the size of a horse, or feet high. the annexed woodcut, fig. ., is one of the restorations which cuvier attempted of the outline of the living animal, derived from the study of the entire skeleton. when the french osteologist declared in the early part of the present century, that all the fossil quadrupeds of the gypsum of paris were extinct, the announcement of so startling a fact, on such high authority, created a powerful sensation, and from that time a new impulse was given throughout europe to the progress of geological investigation. eminent naturalists, it is true, had long before maintained that the shells and zoophytes, met with in many ancient european rocks, had ceased to be inhabitants of the earth, but the majority even of the educated classes continued to believe that the species of animals and plants now contemporary with man, were the same as those which had been called into being when the planet itself was created. it was easy to throw discredit upon the new doctrine by asking whether corals, shells, and other creatures previously unknown, were not annually discovered? and whether living forms corresponding with the fossils might not yet be dredged up from seas hitherto unexamined? but from the era of the publication of cuvier's ossements fossiles, and still more his popular treatise called "a theory of the earth," sounder views began to prevail. it was clearly demonstrated that most of the mammalia found in the gypsum of montmartre differed even generically from any now existing, and the extreme improbability that any of them, especially the larger ones, would ever be found surviving in continents yet unexplored, was made manifest. moreover, the non-admixture of a single living species in the midst of so rich a fossil fauna was a striking proof that there had existed a state of the earth's surface zoologically unconnected with the present order of things. [illustration: fig. . upper molar tooth of _paleotherium magnum_ from isle of wight. (owen's brit. foss. p. .) reduced one-third.] _grès de beauchamp_ ( . _b_, table, p. .).--in some parts of the paris basin, sands and marls, called the grès de beauchamp, or sables moyens, divide the gypseous beds from the underlying calcaire grossier. these sands contain more than species of marine shells, many of them peculiar, but others common to the underlying marine deposit (no. . _c_.). _calcaire grossier_ ( . _c_, table, p. .).--the formation called calcaire grossier consists of a coarse limestone, often passing into sand. it contains the greater number of the fossil shells which characterize the paris basin. no less than distinct species have been procured from a single spot near grignon, where they are embedded in a calcareous sand, chiefly formed of comminuted shells, in which, nevertheless, individuals in a perfect state of preservation, both of marine, terrestrial, and freshwater species, are mingled together. some of the marine shells may have lived on the spot; but the _cyclostoma_ and _limnea_ must have been brought thither by rivers and currents, and the quantity of triturated shells implies considerable movement in the waters. nothing is more striking in this assemblage of fossil testacea than the great proportion of species referable to the genus _cerithium_ (see fig. .). there occur no less than species of this genus in the paris basin, and almost all of them in the calcaire grossier. now the living _cerithia_ inhabit the sea near the mouths of rivers, where the waters are brackish; so that their abundance in the marine strata now under consideration is in harmony with the hypothesis, that the paris basin formed a gulf into which several rivers flowed, the sediment of some of which gave rise to the beds of clay and lignite before mentioned; while a distinct freshwater limestone, called calcaire siliceux, which will presently be described, was precipitated from the waters of others situated farther to the south. [illustration: fig. . cerithium cinctum.[ -a]] [ illustrations: eocene foraminifera. fig. . _calcarina rarispina_, desh. _b_. natural size. _a_, _c_. same magnified. fig. . _spirolina stenostoma_, desh. b. natural size. a, c, d. same magnified. fig. . _triloculina inflata_, desh. _b_. natural size. _a_, _c_, _d_, same magnified. fig. . _clavulina corrugata_, desh. _a_. natural size. _b_, _c_. same magnified.] in some parts of the calcaire grossier round paris, certain beds occur of a stone used in building, and called by the french geologists "miliolite limestone." it is almost entirely made up of millions of microscopic shells, of the size of minute grains of sand, which all belong to the class foraminifera. figures of some of these are given in the annexed woodcut. as this miliolitic stone never occurs in the faluns, or miocene strata of brittany and touraine, it often furnishes the geologist with a useful criterion for distinguishing the detached eocene and miocene formations, scattered over those and other adjoining provinces. the discovery of the remains of paleotherium and other mammalia in some of the upper beds of the calcaire grossier shows that these land animals began to exist before the deposition of the overlying gypseous series had commenced. _calcaire siliceux_.--this compact siliceous limestone extends over a wide area. it resembles a precipitate from the waters of mineral springs, and is often traversed by small empty sinuous cavities. it is, for the most part, devoid of organic remains, but in some places contains freshwater and land species, and never any marine fossils. the siliceous limestone and the calcaire grossier occupy distinct parts of the paris basin, the one attaining its fullest development in those places where the other is of slight thickness. they also alternate with each other towards the centre of the basin, as at sergy and osny; and there are even points where the two rocks are so blended together that portions of each may be seen in hand specimens. thus, in the same bed, at triel, we have the compact freshwater limestone, characterized by its _limneæ_, mingled with the coarse marine limestone, with its small multilocular shells, or "miliolites," dispersed through it in countless numbers. these microscopic testacea are also accompanied by _cerithia_ and other shells of the calcaire grossier. it is very extraordinary that in this instance both kinds of sediment must have been thrown down together on the same spot, yet each retains its own peculiar organic remains. from these facts we may conclude, that while to the north, where the bay was probably open to the sea, a marine limestone was formed, another deposit of freshwater origin was introduced to the southward, or at the head of the bay; for it appears that during the eocene period, as now, the ocean was to the north, and the continent, where the great lakes existed, to the south. from that southern region we may suppose a body of fresh water to have descended, charged with carbonate of lime and silica, the water being perhaps in sufficient volume to freshen the upper end of the bay. the gypseous series ( . _a_, table, p. .), before described, was once supposed to be entirely subsequent in origin to the two groups, called calcaire grossier and calcaire siliceux. but m. prevost has pointed out that in some localities they alternate repeatedly with both. the gypsum, with its associated marl and limestone, is in greatest force towards the centre of the basin, where the calcaire grossier and calcaire siliceux are less fully developed. hence m. prevost infers, that while those two principal deposits were gradually in progress, the one towards the north, and the other towards the south, a river descending from the east may have brought down the gypseous and marly sediment. it must be admitted, as highly probable, that a bay or narrow sea, miles in length, would receive, at more points than one, the waters of the adjoining continent. at the same time, we must be prepared to find that the simultaneous deposition of two or more sets of strata in one basin, some freshwater and others marine, must have produced very complex results. but, in proportion as it is more difficult in these cases to discover any fixed order of superposition in the associated mineral masses, so also is it more easy to explain the manner of their origin, and to reconcile their relations to the agency of known causes. instead of the successive irruptions and retreats of the sea, and changes in the chemical nature of the fluid, and other speculations of the earlier geologists, we are now simply called upon to imagine a gulf, into one extremity of which the sea entered, and at the other a large river, while other streams may have flowed in at different points, whereby an indefinite number of alternations of marine and freshwater beds would be occasioned. lower eocene, france. _lits coquilliers_ ( . _a_, table, p. .).--below the calcaire grossier are extensive deposits of sand, in the upper parts of which some marine beds, called "lits coquilliers," occur, in which m. d'archiac has discovered species of shells. many of these are peculiar, but the larger portion appear to agree with species of the calcaire grossier, so that the line of demarcation usually adopted between the french lower and middle eocene formations, seems not to be very strongly drawn. _sands and plastic clay_ ( . _b_, table, p. .)--at the base of the tertiary system in france are extensive deposits of sands, with occasional beds of clay used for pottery, and called "argile plastique." fossil oysters (_ostrea bellovacina_) abound in some places, and in others there is a mixture of fluviatile shells, such as _cyrena cuneiformis_ (fig. . p. .), _melania inquinata_ (fig. .), and others, frequently met with in beds occupying the same position in the valley of the thames. layers of lignite also accompany the inferior clays and sands. immediately upon the chalk at the bottom of all the tertiary strata there is often a conglomerate or breccia of rolled and angular chalk flints, cemented by siliceous sand. these beds appear to be of littoral origin, and imply the previous emergence of some portions of the chalk, and its waste by denudation. [illustration: fig. . _cardium porulosum_. paris and london basins.] the lower sandy beds of the paris basin are often called the sands of the soissonais, from a district so named miles n.e. of paris. one of the shells of the formation is adduced by m. deshayes as an example of the changes which certain species underwent in the successive stages of their existence. it seems that different varieties of the _cardium porulosum_ are characteristic of different formations. in the lower eocene of the soissonais this shell acquires but a small volume, and has many peculiarities, which disappear in the lowest beds of the calcaire grossier. in these the shell attains its full size, and many distinctive characters, which are again modified in the uppermost beds of the calcaire grossier; and these last modifications of form are preserved throughout the whole of the "upper marine" (or upper eocene) series.[ -a] english eocene formations. the eocene areas of hampshire and london are delineated in the map (fig. . p. .). the following table will show the succession of the principal deposits found in our island. the true place of the bagshot sands, in this series, was never accurately ascertained till mr. prestwich published, in , his classification of the english eocene strata, dividing them into three principal formations, in which the bagshot sands occupied the central place.[ -b] localities. . upper eocene. wanting in great britain. { _a._ freshwater and headon hill, isle of { fluvio-marine beds. wight; and hordwell { cliff, hants. . middle eocene { _b._ barton beds. barton cliff, hants. { _c._ bagshot and bracklesham bagshot heath, surrey; { sands and clays. bracklesham bay, { sussex. { _a._ london clay proper, highgate hill, { and bognor beds. middlesex; i. of { sheppey; bognor, . lower eocene { sussex. { _b._ mottled and plastic newhaven, sussex; { clays and sands. reading, berks; { woolwich, kent. [illustration: fig. . _lymnea longiscata._ freshwater eocene strata, isle of wight.] _freshwater beds_ ( . _a_, table, p. .).--in the northern part of the isle of wight, beds of marl, clay, and sand, and a friable limestone, containing freshwater shells, are seen, containing shells of the genera _lymnea_ (see fig. .), _planorbis_, _melanopsis_, _cyrena_, &c., several of them of the same species as those occurring in the eocene beds of the paris basin. gyrogonites, also, or seed-vessels of _chara_, exhibiting a similar specific identity, occur. at headon hill, on the western side of the island, where these beds are seen in the sea-cliffs, some of the strata contain a few marine and estuary shells, such as _cytheræa_, _corbula_, &c., showing a temporary occupation of the area by brackish or salt water, after which the river or a lake seems again to have prevailed. a species of fan-palm, _flabellaria lamanonis_, brong., like one which characterizes the parisian eocene beds, has been recently detected by dr. mantell in this formation, in whitecliff bay, at the eastern end of the island. several of the species of extinct quadrupeds already alluded to as characterizing the gypsum of montmartre have been discovered by messrs. pratt and fox, in the isle of wight, chiefly at binstead, near ryde, as _palæotherium magnum_, _p. medium_, _p. minus_, _p. minimum_, _p. curtum_, _p. crassum_, also _anoplotherium commune_, _a. secundarium_, _dichobune cervinum_, and _chæropotamus cuvieri_. in hordwell cliff, also on the hampshire coast, several of these species, with other quadrupeds of new genera, such as _paloplotherium_, owen, have been met with; and remains of a remarkable carnivorous genus, _hyænodon_. these fossils are accompanied by the bones of _trionyx_, and other tortoises, and by two land snakes of the genus _paleryx_, owen, from to feet long, also a species of crocodile, and an alligator. among other fossils collected by lady hastings, sir philip egerton has recognized the well-known gar or bony pike of the american rivers, a ganoid fish of the genus _lepidotus_, with its hard shining scales. the shells of hordwell are similar to those of the freshwater beds of the isle of wight, and among them are a few specifically undistinguishable from recent testacea, as _paludina lenta_ and _helix labyrinthica_, the latter discovered by mr. s. wood, and identified with an existing n. american helix. the white and green marls of this freshwater series in hampshire, and some of the accompanying limestones, often resemble those of france in mineral character and colour in so striking a manner, as to suggest the idea that the sediment was derived from the same region, or produced contemporaneously under very similar geographical circumstances. _barton beds._--both in the cliffs of headon hill and hordwell, already mentioned, the freshwater series rests on a mass of pure white sand without fossils, and this is seen in barton cliff to overlie a marine deposit, in which species of testacea have been found. more than half of these are peculiar; and, according to mr. prestwich, only of them common to the london clay proper, being in the proportion of only per cent. on the other hand, of them agree with the _calcaire grossier_ shells. as this is the newest purely marine bed of the eocene series known in england, we might have expected that some of its peculiar fossils would be found to agree with the upper eocene strata described in the last chapter, and accordingly some identifications have been cited with testacea, both of the berlin and belgian strata. it is nearly a century since brander published, in , an account of the organic remains collected from these cliffs, and his excellent figures of the shells then deposited in the british museum are justly admired by conchologists for their accuracy. _bagshot sands_ ( . _c_, table, p. .).--these beds, consisting chiefly of siliceous sand, occupy extensive tracts round bagshot, in surrey, and in the new forest, hampshire. they succeed next in chronological order, and may be separated into three divisions, the upper and lower consisting of light yellow sands, and the central of dark green sands and brown clays, the whole reposing on the london clay proper.[ -a] although the bagshot beds are usually devoid of fossils, they contain marine shells in some places, among which _venericardia planicosta_ (see fig. .) is abundant, with _turritella sulcifera_ and _nummulites lævigatus_. (see fig. . p. .) [illustration: fig. . _venericardia planicosta_, lamck. _cardita planicosta_, deshayes.] at bracklesham bay, near chichester, in sussex, the characteristic shells of this member of the eocene series are best seen; among others, the huge _cerithium giganteum_, so conspicuous in the calcaire grossier of paris, where it is sometimes feet in length. the volutes and cowries of this formation, as well as the lunulites and other corals, seem to favour the idea of a warm climate having prevailed, which is borne out by the discovery of a serpent _palæophis typhæus_, exceeding, according to mr. owen, feet in length, and allied to the boa, python, coluber, and hydrus. the compressed form and diminutive size of certain caudal vertebræ indicate so much analogy with hydrus as to induce the hunterian professor to pronounce the extinct ophidian to have been marine.[ -b] he had previously combated with so much success the evidence advanced, to prove the existence in the northern ocean of sea-serpents in our own times, that he will not be suspected of any undue bias in contending for their former existence in the british eocene seas. the climate, however, of the middle eocene period was evidently far more genial; and amongst the companions of the sea-serpent of bracklesham was an extinct gavial (_gavialis dixoni_, owen), and numerous fish, such as now frequent the seas of warm latitudes, as the sword-fish (see fig. . p. .) and gigantic rays of the genus miliobates. (see fig. .) out of species of testacea procured from the bagshot and bracklesham beds in england, occur in the french calcaire grossier. it was clearly, therefore, coeval with that part of the parisian series more nearly than with any other. the _nummulites lævigatus_ (see fig. .), a fossil characteristic of the lower beds of the calcaire grossier, is abundant at bracklesham. [illustration: fig. . prolonged premaxillary bone or "sword" of a fossil sword-fish (_cælorhynchus_). bracklesham. dixon's fossils of sussex, pl. .] [illustration: fig. . dental plates of _myliobates edwardsi_. bracklesham bay. ibid. pl. .] [illustration: fig. . _nummulites_ (_nummularia_) _lævigatus._ bracklesham. ibid. pl. . _a._ section of the nummulite. _b._ group, with an individual showing the exterior of the shell.] _london clay proper_ ( . _a_, table, p. .).--this formation underlies the preceding, and consists of tenacious brown and blueish grey clay, with layers of concretions called septaria, which abound chiefly in the brown clay, and are obtained in sufficient numbers from the cliffs near harwich, and from shoals of the essex coast, to be used for making roman cement. the principal localities of fossils in the london clay are highgate hill, near london, the island of sheppey, and bognor in hampshire. out of fossil shells, mr. prestwich found only to be common to the calcaire grossier (from which species have been obtained), while are common to the lits coquilliers (p. .), in which only species are known in france. we may presume, therefore, that the london clay proper is older than the calcaire grossier. this may perhaps remove a difficulty which m. adolphe brongniart has experienced when comparing the eocene flora of the neighbourhoods of london and paris. the fossil species of the island of sheppey, he observes, indicate a much more tropical climate than the eocene flora of france, which has been derived principally from the "gypseous series." the latter resembles the vegetation of the borders of the mediterranean rather than that of an equatorial region. mr. bowerbank, in a valuable publication on the fossil fruits and seeds of the island of sheppey, near london, has described no less than thirteen fruits of palms of the recent type _nipa_, now only found in the molucca and philippine islands. (see fig. .) these plants are allied to the cocoa-nut tribe on the one side, and on the other to the _pandanus_, or screw-pine. species of cocoa-nuts are also met with, and other kinds of palms; also three species of _anona_, or custard-apple; cucurbitaceous fruits, also (the gourd and melon family), are in considerable abundance. fruits of various species of _acacia_ are in profusion; and, although less decidedly tropical, imply a warm climate. [illustration: fig. . _nipadites ellipticus._ bow. fossil palm of sheppey.] the contiguity of land may be inferred not only from these vegetable productions, but also from the teeth and bones of crocodiles and turtles, since these creatures, as mr. conybeare has remarked, must have resorted to some shore to lay their eggs. of turtles there were numerous species referred to extinct genera, and, for the most part, not equal in size to the largest living tropical turtles. a snake, which must have been feet long, of the genus _palæophis_ before mentioned, has also been described by mr. owen from sheppey, of a different species from that of bracklesham. a true crocodile, also, _crocodilus toliapicus_, and another saurian more nearly allied to the gravial, accompany the above fossils. a bird allied to the vultures, and a quadruped of the new genus _hyracotherium_, allied to the hyrax, hog, and chæropotamus, are also among the additions made of late years to the palæontology of this division. [ illustrations: fossil shells of the london clay. fig. . _mitra scabra_. fig. . _rostellaria macroptera_, sow. one-third of nat. size. fig. . _crassatella sulcata._] the marine shells of the london clay confirm the inference derivable from the plants and reptiles of a high temperature. thus, many species of _conus_, _mitra_, and _voluta_ occur, a large _cypræa_, a very large _rostellaria_, and shells of the genera _terebellum_, _cancellaria_, _crassatella_, and others, with four or more species of _nautilus_ (see fig. .) and other cephalopoda of extinct genera, one of the most remarkable of which is the _belosepia_.[ -a] (see fig. .) [illustration: fig. . _nautilus centralis._] [illustration: fig. . _voluta athleta._] [illustration: fig. . _terebellum fusiforme._] [illustration: fig. . _aturia zigzag._ bronn. syn. _nautilus zigzag._ sow. london clay. sheppey.] [illustration: fig. . _belosepia sepiodea_, de blainv. london clay. sheppey.] the above shells are accompanied by a sword-fish (_tetrapterus priscus_, agassiz), about feet long, and a saw-fish (_pristis bisulcatus_, ag.), about feet in length; genera now foreign to the british seas. on the whole, no less than species of fish have been described by m. agassiz from these beds in sheppey, and they indicate, in his opinion, a warm climate. [illustration: fig. . molar of monkey (_macacus_).] _strata of kyson in suffolk._--at kyson, a few miles east of woodbridge, a bed of eocene clay, feet thick, underlies the red crag. beneath it is a deposit of yellow and white sand, of considerable interest, in consequence of many peculiar fossils contained in it. its geological position is probably the lowest part of the london clay proper. in this sand has been found the first example of a fossil quadrumanous animal discovered in great britain, namely, the teeth and part of a jaw, shown by mr. owen to belong to a monkey of the genus _macacus_ (see fig. .). the mammiferous fossils, first met with in the same bed, were those of an opossum (_didelphys_) (see fig. .), and an insectivorous bat (fig. .), together with many teeth of fishes of the shark family. mr. colchester in obtained other mammalian relics from kyson, among which mr. owen has recognized several teeth of the genus _hyracotherium_, and the vertebræ of a large serpent, probably a _palæophis_. as the remains both of the _hyracotherium_ and _palæophis_ were afterwards met with in the london clay, as before remarked, these fossils confirmed the opinion previously entertained, that the kyson sand belongs to the eocene period. the _macacus_, therefore, constitutes the first example of any quadrumanous animal found in strata as old as the eocene, or so far from the equator as lat. ° n. it was not until after the year that the existence of any fossil quadrumana was brought to light. since that period they have been found in france, india, and brazil. [illustration: fig. . molar tooth and part of jaw of opossum. from kyson.[ -a]] [illustration: fig. . molars of insectivorous bats, twice nat. size. from kyson, suffolk.] _mottled or plastic clays_, _&c._ ( . _b_, table, p. .).--no formations can be more dissimilar on the whole in mineral character than the eocene deposits of england and paris; those of our own island being almost exclusively of mechanical origin,--accumulations of mud, sand, and pebbles; while in the neighbourhood of paris we find a great succession of strata composed of a coarse white limestone, and compact siliceous limestone with beds of crystalline gypsum and siliceous sandstone, and sometimes pure flint used for millstones. hence it is by no means an easy task to institute an exact comparison between the various members of the english and french series, and to settle their respective ages. it is clear that a continual change was going on in the fauna and flora by the coming in of new species and the dying out of others; and contemporaneous changes of geographical conditions were also in progress in consequence of the rising and sinking of the land and bottom of the sea. a particular subdivision, therefore, of time was occasionally represented in one area by land, in another by an estuary, in a third by the sea, and even where the conditions were in both areas of a marine character, there was often shallow water in one, and deep sea in another, producing a want of agreement in the state of animal life. at the commencement, however, of the eocene formations in france and england, we find an exception to this rule, for a marked similarity of mineral character reigns in the lowest division, whether in the basins of paris, hampshire, or london. this uniformity of aspect must be seen in order to be fully appreciated, since the beds consist simply of sand, mottled clays, and well-rolled flint pebbles, derived from the chalk, and varying in size from that of a pea to an egg. these strata may be seen at reading, at blackheath, near london, and at woolwich. in some of the lowest of them, banks of oysters are observed, consisting of _ostrea bellovicina_, so common in france in the same relative position, and _ostrea edulina_, scarcely distinguishable from the living eatable species. in this formation at bromley, dr. buckland found one large pebble to which five full-grown oysters were affixed, in such a manner as to show that they had commenced their first growth upon it, and remained attached to it through life. in several places, as at woolwich on the thames, at newhaven in sussex, and elsewhere, a mixture of marine and freshwater testacea distinguishes this member of the series. among the latter, _melania inquinata_ (see fig. .) and _cyrena cuneiformis_ are very common. they probably indicate points where rivers entered the eocene sea. [illustration: fig. . _cyrena cuneiformis_, min. con. natural size.] [illustration: fig. . _melania inquinata_, des. nat. size. syn. _cerithium melanoides_, min. con.] with us as in france, clay of this formation is used in some places, as near poole in dorsetshire, for pottery; and hence the name of plastic clay was adopted for the group by mr. t. webster. lignite also is associated with it in some spots, as in the paris basin. before the minds of geologists had become familiar with the theory of the gradual sinking of the land, and its conversion into sea at different periods, and the consequent change from shallow to deep water, the freshwater and littoral character of this inferior group appeared strange and anomalous. after passing through many hundred feet of london clay, proved by its fossils to have been deposited in salt water of considerable depth, we arrive at beds of fluviatile origin. thick masses, also, of shingle indicate the proximity of land, where the flints of the chalk were rolled into sand and pebbles, and spread continuously over wide spaces, as in the isle of wight, in the south of hampshire, and near london, always appearing at the bottom of the eocene series. it may be asked why they did not constitute simply a narrow littoral zone, such as we might look for in strata formed at a moderate distance from the shore. in answer to this inquiry, the student must be reminded, that wherever a gently-sloping land is gradually sinking and becoming submerged, shingle may be heaped up successively over a wide area, although marine currents have no power of dispersing it simultaneously over a large space. in such cases it is not the shingle which recedes from the coast, but the coast which recedes from the shingle, which is formed one mass after another as often as successive portions of the land are converted into sea and others into a sea beach. the london area appears to have been upraised before that of hampshire, so that it never became the receptacle of the barton clays, nor of the overlying fluvio-marine and freshwater beds of hordwell and the north part of the isle of wight. on the other hand, the hampshire eocene area seems to have emerged before that of paris, so that no marine beds of the upper eocene era were ever thrown down in hampshire. _nummulitic formation of the alps and pyrenees._--it has long been matter of controversy, whether the nummulitic rocks of the alps and pyrenees should be regarded as eocene or cretaceous; but the number of geologists of high authority who regard this important group as belonging to the lowest tertiary system of europe has for many years been steadily increasing. the late m. alex. brongniart first declared the specific identity of many of the shells of this formation with those of the marine strata near paris, although he obtained them from the summit of the diablerets, one of the loftiest of the swiss alps, which rises more than , feet above the level of the sea. deposits of the same age, found on the flanks of the pyrenees, contain also a great number of shells common to the paris and london areas, and three or four species only which are common to the cretaceous formation. the calcareous division consists often of a compact crystalline marble, full of nummulites (see fig. .), shells of the class _foraminifera_. [illustration: fig. . _nummulites_. peyrehorade, pyrenees. _a._ external surface of one of the nummulites, of which longitudinal sections are seen in the limestone. _b._ transverse section of same.] the nummulitic limestone of the alps is often of great thickness, and is immediately covered by another series of strata of dark-coloured slates, marls, and fucoidal sandstones, to the whole of which the provincial name of "flysch" has been given in parts of switzerland. the researches of sir roderick murchison in the alps in enable us to refer the whole of these beds to the eocene period, and it seems probable that they most nearly coincide in age with the lower eocene. they enter into the disturbed and loftiest portions of the alpine chain, to the elevation of which they enable us therefore to assign a comparatively modern date. the nummulitic formation, with its characteristic fossils, plays a far more conspicuous part than any other tertiary group in the solid framework of the earth's crust, whether in europe, asia, or africa. it often attains a thickness of many thousand feet, and extends from the alps to the apennines. it is found in the carpathians, and in full force in the north of africa, as, for example, in algeria and morocco. it has also been traced from egypt into asia minor, and across persia by bagdad to the mouths of the indus. it occurs not only in cutch, but in the mountain ranges which separate scinde from persia, and which form the passes leading to caboul; and it has been followed still farther eastward into india. some members of this lower tertiary formation in the central alps, including even the superior strata called _flysch_, have been converted into crystalline rocks, and changed into saccharoid marble, quartz, rock, and mica-schist.[ -a] eocene strata in the united states. in north america the eocene formations occupy a large area bordering the atlantic, which increases in breadth and importance as it is traced southwards from delaware and maryland to georgia and alabama. they also occur in louisiana and other states both east and west of the valley of the mississippi. at claiborne in alabama no less than four hundred species of marine shells, with many echinoderms and teeth of fish, characterize one member of this system. among the shells the _cardita planicosta_, before mentioned (fig. . p. .), is in abundance; and this fossil, and some others identical with european species, or very nearly allied to them, make it highly probable that the claiborne beds agree in age with the central or bracklesham group of england, and the calcaire grossier of paris.[ -b] higher in the series is a remarkable calcareous rock, formerly called "the nummulite limestone," from the great number of discoid bodies resembling nummulites which it contains, fossils now referred by a. d'orbigny to the genus _orbitoides_, which has been demonstrated by dr. carpenter to belong to the foraminifera.[ -c] the following section will enable the reader to understand the position of the three subdivisions of the series, nos. , , and ., the relations of which i ascertained in clarke county, between the rivers alabama and tombeckbee. [illustration: fig. . cross section. . sand, marl, &c., with numerous fossils. } . white or rotten limestone, with _zeuglodon_. } eocene. . orbitoidal, or so called nummulitic limestone. } . overlying formation of sand and clay without fossils. age unknown.] the lowest set of strata, no. ., having a thickness of more than feet, comprise marly beds, in which the _ostrea sellæformis_ occurs, a shell ranging from alabama to virginia, and being a representative form of the _ostrea flabellula_ of the eocene group of europe. in others beds of no. ., two european shells, _cardita planicosta_, before mentioned, and _solarium canaliculatum_ are found, with a great many other species peculiar to america. numerous corals, also, and the remains of placoid fish and of rays occur, and the "swords," as they are called, of sword fishes, all bearing a great generic likeness to those of the eocene strata of england and france. no. . (fig. .) is a white limestone, sometimes soft and argillaceous, but in parts very compact and calcareous. it contains several peculiar corals, and a large nautilus allied to _n. zigzag_, also in its upper bed a gigantic cetacean, called _zeuglodon_ by owen.[ -a] [ illustrations: _zeuglodon cetoides_, owen. _basilosaurus_, harlan.] fig. . molar tooth, natural size.] fig. . vertebra, reduced.] the colossal bones of this cetacean are so plentiful in the interior of clarke county as to be characteristic of the formation. the vertebral column of one skeleton found by dr. buckley at a spot visited by me, extended to the length of nearly feet, and not far off part of another backbone nearly feet long was dug up. i obtained evidence, during a short excursion, of so many localities of this fossil animal within a distance of miles, as to lead me to conclude that they must have belonged to at least forty distinct individuals. mr. owen first pointed out that the huge animal was not reptilian, since each tooth was furnished with double roots (see fig. .), implanted in corresponding double sockets; and his opinion of the cetacean nature of the fossil was afterwards confirmed by dr. wyman and professor r. w. gibbes. that it was an extinct species of the whale tribe has since been placed beyond all doubt by the discovery of the entire skull of another fossil of the same family, found to have the double occipital condyles only met with in mammals, and the convoluted tympanic bones which are characteristic of cetaceans. near the junction of no. . and the incumbent limestone, no. ., next to be mentioned, are strata characterized by the following shells: spondylus dumosus (_plagiostoma dumosum_, morton), _pecten poulsoni_, _pecten perplanus_, and _ostrea cretacea_. no. . (fig. .) is a white limestone, for the most part made up of the _orbitoides_ of d'orbigny before mentioned (p. .), formerly supposed to be a nummulite, and called _n. mantelli_, mixed with a few lunulites and small corals and shells.[ -a] the origin of this cream-coloured soft stone, like that of our white chalk, which it much resembles, is, i believe, due to the decomposition of the orbitoides. the surface of the country where it prevails is sometimes marked by the absence of wood, like our chalk downs, or is covered exclusively by the _juniperus virginiana_, as certain chalk districts in england by yew trees and juniper. some of the shells of this limestone are common to the claiborne beds, but many of them are peculiar. it will be seen in the section (fig. . p. .) that the strata, nos. , , ., are, for the most part, overlaid by a dense formation of sand or clay without fossils. in some points of the bluff or cliff of the alabama river, at claiborne, the beds nos. , ., are exposed nearly from top to bottom, whereas at other points the newer formation, no. ., occupies the face of nearly the whole cliff. the age of this overlying mass has not yet been determined, as it has hitherto proved destitute of organic remains. the burr-stone strata of the southern states contain so many fossils agreeing with those of claiborne, that it doubtless belongs to the same part of the eocene group, though i was not fortunate enough to see the relations of the two deposits in a continuous section. mr. tuomey considers it as the lower portion of the series. it may, perhaps, be a form of the claiborne beds in places where lime was wanting, and where silex, derived from the decomposition of felspar, predominated. it consists chiefly of slaty clays, quartzose sands, and loam, of a brick red colour, with layers of chert or burr-stone, used in some places for millstones. footnotes: [ -a] leyde magaz. voor wetensch konst en lett., partie v. cahier i. p. . cited by rozet, journ. de géologie, tom. i. p. . [ -b] m. c. prevost, submersions itératives, &c. note . [ -a] cuvier, oss. foss., tom. iii. p. . [ -a] this species is found both in the paris and london basins. [ -a] coquilles caractérist. des terrains, . [ -b] quarterly geol. journal, vol. iii. p. . [ -a] prestwich, quart. geol. journ. vol. iii. p. . [ -b] palæont. soc. monograph. rept. pt. ii. p. . [ -a] for description of eocene cephalopoda, see monograph by f. e. edwards, palæontograph. soc. . [ -a] annals of nat. hist. vol. iv. no. . nov. . [ -a] murchison, quart. journ. of geol. soc. vol. v., and lyell, vol. vi. . anniversary address. [ -b] see paper by the author, quart. journ. geol. soc. vol. iv, p. .; and second visit to the u. s. vol. ii. p. . [ -c] quart. journ. geol soc. vol. vi. p. . [ -a] see memoir by r. w. gibbes, journ. of acad. nat. sci. philad. vol. i. . [ -a] lyell, quart. journ. geol. soc. , vol. iv. p. . chapter xvii. cretaceous group. divisions of the cretaceous series in north-western europe--upper cretaceous strata--maestricht beds--chalk of faxoe--white chalk--characteristic fossils--extinct cephalopoda--sponges and corals of the chalk--signs of open and deep sea--wide area of white chalk--its origin from corals and shells--single pebbles in chalk--siliceous sandstone in germany contemporaneous with white chalk--upper greensand and gault--lower cretaceous strata--atherfield section, isle of wight--chalk of south of europe--hippurite limestone--cretaceous flora--chalk of united states. having treated in the preceding chapters of the tertiary strata, we have next to speak of the uppermost of the secondary groups, called the chalk or cretaceous (no. . table, p. .), because in those parts of europe where it was first studied its upper members are formed of that remarkable white earthy limestone, termed chalk (_creta_). the inferior division consists, for the most part, of clays and sands, called greensand, because some of the sands derive a bright green colour from intermixed grains of chloritic matter. the cretaceous strata in the north-west of europe may be thus divided[ -a]: _upper cretaceous._ . maestricht beds and faxoe limestone. . upper white chalk, with flints. . lower white chalk, without flints, passing downwards into chalk marl, which is slightly argillaceous. . upper greensand. . gault. _lower cretaceous._ . lower greensand--ironsand, clay, and occasional beds of limestone (kentish rag). _maestricht beds._--on the banks of the meuse, at maestricht, reposing on ordinary white chalk with flints, we find an upper calcareous formation about feet thick, the fossils of which are, on the whole, very peculiar, and all distinct from tertiary species. some few are of species common to the inferior white chalk, among which may be mentioned _belemnites mucronatus_ (see fig. .) and _pecten quadricostatus_. besides the belemnite there are other _genera_, such as ammonite, baculite, and hamite, never found in strata newer than the cretaceous, but frequently met with in these maestricht beds. on the other hand, volutes and other genera of univalve shells, usually met with only in tertiary strata, occur. the upper part of the rock, about feet thick, as seen in st. peter's mount, in the suburbs of maestricht, abounds in corals, often detachable from the matrix; and these beds are succeeded by a soft yellowish limestone feet thick, extensively quarried from time immemorial for building. the stone below is whiter, and contains occasional nodules of grey chert or chalcedony. m. bosquet, with whom i lately examined this formation (august, ), pointed out to me a layer of chalk from to inches thick, containing green earth and numerous encrinital stems, which forms the line of demarcation between the strata containing the fossils peculiar to maestricht and the white chalk below. the latter is distinguished by regular layers of black flint in nodules, and by several shells, such as _terebratula carnea_ (see fig. .), wholly wanting in beds higher than the green band. some of the organic remains, however, for which st. peter's mount is celebrated, occur both above and below that parting layer, and, among others, the great marine reptile, called _mosasaurus_, a saurian supposed to have been feet in length, of which the entire skull and a great part of the skeleton have been found. such remains are chiefly met with in the soft freestone, the principal member of the maestricht beds. _chalk of faxoe._--in the island of seeland, in denmark, the newest member of the chalk series, seen in the sea-cliffs at stevens klint resting on white chalk with flints, is a yellow limestone, a portion of which, at faxoe, where it is used as a building-stone, is composed of corals, even more conspicuously than is usually observed in recent coral reefs. it has been quarried to the depth of more than feet, but its thickness is unknown. the imbedded shells are chiefly casts, many of them of univalve mollusca, which, as they strictly belong to the cretaceous era, are worthy of notice, since such forms, whether spiral or patelliform, are wanting in the white chalk of europe generally. thus, there are two species of _cypræa_, one of _oliva_, two of _mitra_, four of the genus _cerithium_, six of _fusus_, two of _trochus_, one _patella_, one _emarginula_, &c., on the whole, more than thirty univalves, spiral or patelliform, not one of which is common to the white chalk. at the same time, a large proportion of the accompanying bivalve shells, echinoderms, and zoophytes, are specifically identical with fossils of older parts of the cretaceous series. among the cephalopoda of faxoe, may be mentioned _baculites faujasii_ and _belemnites mucronatus_, shells of the white chalk. the claws and entire shell of a small crab, _brachyurus rugosus_ (schlotheim), are scattered through the faxoe stone, reminding us of similar crustaceans enclosed in the rocks of many modern coral reefs.[ -a] some small portions of this coralline formation consist of white earthy chalk; it is, therefore, clear that this substance must have been produced simultaneously, a fact of some importance, as bearing on the theory of the origin of white chalk; for the decomposition of such corals as we see at faxoe is capable, we know, of forming white mud, undistinguishable from chalk, and which we may suppose to have been dispersed far and wide through the ocean, in which such reefs as that of faxoe grew. [illustration: fig. . section from hertfordshire, in england, to sena, in france.] _white chalk_ ( . and . tab. p. .).--the highest beds of chalk in england and france consist of a pure, white, calcareous mass, usually too soft for a building stone, but sometimes passing into a more solid state. it consists, almost purely, of carbonate of lime; the stratification is often obscure, except where rendered distinct by interstratified layers of flint, a few inches thick, occasionally in continuous beds, but oftener in nodules, and recurring at intervals from to feet distant from each other. this upper chalk is usually succeeded, in the descending order, by a great mass of white chalk without flints, below which comes the chalk marl, in which there is a slight admixture of argillaceous matter. the united thickness of the three divisions in the south of england equals, in some places, feet.[ -b] the annexed section, fig. ., will show the manner in which the white chalk extends from england into france, covered by the tertiary strata described in former chapters, and reposing on lower cretaceous beds. among the conspicuous forms of mollusca wholly foreign to the tertiary and recent periods, and which we meet with in the white chalk, are the belemnite, ammonite, baculite, and turrilite, all genera of _cephalopoda_, a family to which the living cuttle-fish and nautilus belong. [illustration: fig. . portion of _baculites faujasii_. maestricht and faxoe beds and white chalk.] [illustration: fig. . portion of _baculites anceps_. maestricht and faxoe beds and white chalk.] [illustration: fig. . turrilites. _a._ _turrilites costatus._ chalk marl. _b._ same, showing the indented border of the partition of the chambers.] [illustration: fig. . belemnites. _a._ _belemnites mucronatus._ _b._ same, showing internal structure. maestricht, faxoe, and white chalk.] among the brachiopoda in the white chalk, the _terebratulæ_ are very abundant. these shells are known to live at the bottom of the sea, where the water is tranquil and of some depth (see figs. , , , .). with these are associated some forms of oyster (see figs. . and .), and other bivalves (figs. , , , , .). [illustration: fig. . _terebratula plicatilis_, dorsal view. upper white chalk.] [illustration: fig. . _terebratula plicatilis_, side view.] [illustration: fig. . _terebratula pumilus._ (_magas pumilus_, sow.) upper white chalk.] [illustration: fig. . _terebratula carnea._ upper white chalk.] [illustration: fig. . _ostrea vesicularis._ _gryphæa globosa_, min. con. upper chalk and upper greensand.] [illustration: fig. . _pecten -costatus._ white chalk, upper and lower greensands.] [illustration: fig. . _ostrea carinata._ chalk marl, upper and lower greensands.] [illustration: fig. . _crania parisiensis_, inferior or attached valve. upper white chalk.] [illustration: fig. . _plagiostoma hoperi_, sow. syn. _lima hoperi_. white chalk and upper greensand.] [illustration: fig. . _plagiostoma spinosum_, sow. syn. _spondylus spinosus_. upper white chalk.] among the rest, no form marks the cretaceous era in europe, america, and india, in a more striking manner than the extinct genus _inoceramus_ (_catillus_ of lamk.), the shells of which are distinguished by a fibrous texture, and are often met with in fragments, having, probably, been extremely friable. [illustration: fig. . _inoceramus lamarckii._ syn. _catillus lamarckii_. white chalk (dixon's geol. sussex, tab. . fig. .)] [illustration: fig. . _eschara disticha._ _a._ natural size. _b._ portion magnified. white chalk.] [ illustrations: fig. . fig. . a branching sponge in a flint, from the white chalk. from the collection of mr. bowerbank.] with these mollusca are many corals (figs. , , .) and sea urchins (fig. .), which are alike marine, and, for the most part, indicative of a deep sea. they are dispersed indifferently through the soft chalk, and hard flint, and some of the flinty nodules owe their irregular forms to inclosed zoophytes, as in the specimen represented in fig. ., where the hollows in the exterior are caused by the branches of a sponge seen on breaking open the flint, fig. . [illustration: fig. . _ananchytes ovata_. white chalk, upper and lower. _a_. side view. _b_. bottom of the shell on which both the oral and anal apertures are placed; the anal being more round, and at the smaller end.] of the singular family called _rudistes_, by lamarck, hereafter to be mentioned, as extremely characteristic of the chalk of southern europe, a single representative only (fig. .) has been discovered in the white chalk of england. [ illustrations: _hippurites mortoni_, mantell. houghton, sussex. white chalk. diameter one seventh of nat. size. fig. . two individuals deprived of their opercula, adhering together. fig. . same seen from above. fig. . transverse section of part of the wall of the shell, magnified to show the structure. fig. . vertical section of the same. on the side where the shell is thinnest, there is one external furrow and corresponding internal ridge, a, b. figs. , .; but they are usually less prominent than in these figures. this species has been referred to _hippurites_, but does not, i believe, fully agree in character with that genus. i have never seen the opercular piece, or _valve_, as it is called by those conchologists who regard the _rudistes_ as bivalve mollusca. the specimen above figured was discovered by the late mr. dixon.] the remains of fishes of the upper cretaceous formations consist chiefly of teeth of the shark family of genera, in part common to the tertiary, and partly distinct. but we meet with no bones of land animals, nor any terrestrial or fluviatile shells, nor any plants, except sea weeds, and here and there a piece of drift wood. all the appearances concur in leading us to conclude that the white chalk was the product of an open sea of considerable depth. the existence of turtles and oviparous saurians, and of a pterodactyl or winged-lizard, found in the white chalk of maidstone, implies, no doubt, some neighbouring land; but a few small islets in mid-ocean, like ascension, so much frequented by migratory droves of turtles, might perhaps have afforded the required retreat where these creatures might lay their eggs in the sand, or from which the flying species may have been blown out to sea. of the vegetation of such islands we have scarcely any indication, but it consisted partly of cycadeous plants; for a fragment of one of these was found by capt. ibbetson in the chalk marl of the isle of wight, and is referred by a. brongniart to _clathraria lyellii_, mantell, a species common to the antecedent wealden period. _geographical extent and origin of the while chalk._--the area over which the white chalk preserves a nearly homogeneous aspect is so vast, that the earlier geologists despaired of discovering any analogous deposits of recent date. pure chalk, of nearly uniform aspect and composition, is met with in a north-west and south-east direction, from the north of ireland to the crimea, a distance of about geographical miles; and in an opposite direction it extends from the south of sweden to the south of bordeaux, a distance of about geographical miles. in southern russia, according to sir r. murchison, it is sometimes feet thick, and retains the same mineral character as in france and england, with the same fossils, including _inoceramus cuvieri_, _belemnites mucronatus_, and _ostrea vesicularis_. but it would be an error to imagine, that the chalk was ever spread out continuously over the whole of the space comprised within these limits, although it prevailed in greater or less thickness over large portions of that area. on turning to those regions of the pacific where coral reefs abound, we find some archipelagoes of lagoon islands, such as that of the dangerous archipelago, for instance, and that of radack, with several adjoining groups, which are from to miles in length, and or miles broad; and the space to which flinders proposed to give the name of the corralline sea is still larger; for it is bounded on the east by the australian barrier--all formed of coral rock,--on the west by new caledonia, and on the north by the reefs of louisiade. although the islands in these areas may be thinly sown, the mud of the decomposing zoophytes may be scattered far and wide by oceanic currents. that this mud would resemble chalk i have already hinted when speaking of the faxoe limestone, p. .; and it was also remarked in an early part of this volume, that some even of that chalk which appears to an ordinary observer quite destitute of organic remains, is nevertheless, when seen under the microscope, full of fragments of corals and sponges; together with the valves of entomostraca, the shells of foraminifera, and still more minute infusoria.[ -a] (see p. .) now it had been often suspected, before these discoveries, that white chalk might be of animal origin, even where every trace of organic structure has vanished. this bold idea was partly founded on the fact, that the chalk consisted of pure carbonate of lime, such as would result from the decomposition of testacea, echini, and corals; and partly on the passage observable between these fossils when half decomposed and chalk. but this conjecture seemed to many naturalists quite vague and visionary, until its probability was strengthened by new evidence brought to light by modern geologists. we learn from lieutenant nelson, that, in the bermuda islands, there are several basins or lagoons almost surrounded and enclosed by reefs of coral. at the bottom of these lagoons a soft white calcareous mud is formed by the decomposition of _eschara_, _flustra_, _cellepora_, and other corallines. this mud, when dried, is undistinguishable from common white earthy chalk; and some portions of it, presented to the museum of the geological society of london, might, after full examination, be mistaken for ancient chalk, but for the labels attached to them. about the same time mr. c. darwin observed similar facts in the coral islands of the pacific; and came also to the opinion, that much of the soft white mud found at the bottom of the sea near coral reefs has passed through the bodies of worms, by which the stony masses of coral are everywhere bored; and other portions through the intestines of fishes; for certain gregarious fishes of the genus _sparus_ are visible through the clear water, browsing quietly, in great numbers, on living corals, like grazing herds of graminivorous quadrupeds. on opening their bodies, mr. darwin found their intestines filled with impure chalk. this circumstance is the more in point, when we recollect how the fossilist was formerly puzzled by meeting, in chalk, with certain bodies, called cones of the larch, which were afterwards recognized by dr. buckland to be the excrement of fish.[ -a] these spiral coprolites (see figures), like the scales and bones of fossil fish in the chalk, are composed chiefly of phosphate of lime. [ illustrations: fig. . fig. . coprolites of fish called _iulo-eido-copri_, from the chalk.] mr. dana, when describing the elevated coral reef of oahu, in the sandwich islands, says, that some varieties of the rock consist of aggregated shells, imbedded in a compact calcareous base as firm in texture as any secondary limestone; while others are like chalk, having its colour, its earthy fracture, its soft homogeneous texture, and being an equally good writing material. the same author describes, in many growing coral reefs, a similar formation of modern chalk, undistinguishable from the ancient.[ -b] the extension over a wide submarine area of the calcareous matrix of the chalk, as well as of the imbedded fossils, would take place the more readily, in consequence of the low specific gravity of the shells of mollusca and zoophytes, when compared with ordinary sand and mineral matter. the mud also derived from their decomposition would be much lighter than argillaceous and other inorganic mud, and very easily transported by currents, especially in salt water. _single pebbles in chalk._--the general absence of sand and pebbles in the white chalk has been already mentioned; but the occurrence here and there, in the south-east of england, of a few isolated pebbles of quartz and green schist, some of them or inches in diameter, has justly excited much wonder. if these had been carried to the spots where we now find them by waves or currents from the lands once bordering the cretaceous sea, how happened it that no sand or mud were transported thither at the same time? we cannot conceive such rounded stones to have been drifted like erratic blocks by ice[ -a], for that would imply a cold climate in the cretaceous period; a supposition inconsistent with the luxuriant growth of large chambered univalves, numerous corals, and many fish, and other fossils of tropical forms. now in keeling island, one of those detached masses of coral which rise up in the wide pacific, captain ross found a single fragment of greenstone, where every other particle of matter was calcareous; and mr. darwin concludes that it must have come there entangled in the roots of a large tree. he reminds us that chamisso, the distinguished naturalist who accompanied kotzebue, affirms, that the inhabitants of the radack archipelago, a group of lagoon islands, in the midst of the pacific, obtained stones for sharpening their instruments by searching the roots of trees which are cast up on the beach.[ -b] it may perhaps be objected, that a similar mode of transport cannot have happened in the cretaceous sea, because fossil wood is very rare in the chalk. nevertheless wood is sometimes met with, and in the same parts of the chalk where the pebbles are found, both in soft stone and in a silicified state in flints. in these cases it has often every appearance of having been floated from a distance, being usually perforated by boring-shells, such as the _teredo_ and _fistulana_.[ -c] the only other mode of transport which suggests itself is sea-weed. dr. beck informs me, that in the lym-fiord, in jutland, the _fucus vesiculosus_, often called kelp, sometimes grows to the height of feet, and the branches rising from a single root form a cluster several feet in diameter. when the bladders are distended, the plant becomes so buoyant as to float up loose stones several inches in diameter, and these are often thrown by the waves high up on the beach. the _fucus giganteus_ of solander, so common in terra del fuego, is said by captain cook to attain the length of feet, although the stem is not much thicker than a man's thumb. it is often met with floating at sea, with shells attached, several hundred miles from the spots where it grew. some of these plants, says mr. darwin, were found adhering to large loose stones in the inland channels of terra del fuego, during the voyage of the beagle in ; and that so firmly, that the stones were drawn up from the bottom into the boat, although so heavy that they could scarcely be lifted in by one person. some fossil sea-weeds have been found in the cretaceous formation, but none, as yet, of large size. but we must not imagine that because pebbles are so rare in the white chalk of england and france there are no proofs of sand, shingle, and clay having been accumulated contemporaneously even in the european seas. the siliceous sandstone, called "upper quader" by the germans, overlies white argillaceous chalk, or "pläner-kalk," a deposit resembling in composition and organic remains the chalk marl of the english series. this sandstone contains as many fossil shells common to our white chalk as could be expected in a sea-bottom formed of such different materials. it sometimes attains a thickness of feet, and by its jointed structure and vertical precipices, plays a conspicuous part in the picturesque scenery of saxon switzerland, near dresden. _upper greensand_ ( . tab. p. .).--the lower chalk without flints passes gradually downwards, in the south of england, into an argillaceous limestone, "the chalk marl," already alluded to, in which ammonites and other cephalopoda, so rare in the higher parts of the series, appear. this marly deposit passes in its turn into beds containing green particles of a chloritic mineral, called the upper greensand. in parts of surrey calcareous matter is largely intermixed, forming a stone called _firestone_. in the cliffs of the southern coast of the isle of wight, this upper greensand is feet thick, and contains bands of siliceous limestone and calcareous sandstone with nodules of chert. [ illustrations: fossils of the upper greensand. fig. . _a._ _terebratula lyra._ } upper greensand. _b._ same, seen in profile. } france. fig. . _ammonites rhotomagensis._ upper greensand.] [illustration: fig. . _hamites spiniger_ (fitton); near folkstone. gault.] _gault._--the lowest member of the upper cretaceous group, usually about feet thick in the s.e. of england, is provincially termed gault. it consists of a dark blue marl, sometimes intermixed with greensand. many peculiar forms of cephalopoda, such as the _hamite_ (fig. .) and _scaphite_, with other fossils, characterize this formation, which, small as is its thickness, can be traced by its organic remains to distant parts of europe, as, for example, to the alps. the phosphate of lime, found lately near farnham, in surrey, in such abundance as to be used largely by the agriculturist for fertilizing soils, occurs exclusively, according to mr. r. a. c. austen, in the upper greensand and gault. it is doubtless of animal origin, and partly coprolitic, probably derived from the excrement of fish. lower cretaceous division. (no. . tab. p. .) that part of the cretaceous series which is older than the gault has been commonly called the lower greensand. the greater number of its fossils are specifically distinct from those of the upper cretaceous system. dr. fitton, to whom we are indebted for an excellent monograph on this formation as developed in england, gives the following as the succession of rocks seen in parts of kent. no. . sand, white, yellowish, or ferruginous, with concretions of limestone and chert feet. . sand with green matter to feet. . calcareous stone, called kentish rag to feet. in his detailed description of the fine section displayed at atherfield, in the south of the isle of wight, we find the limestone wholly wanting; in fact, the variations in the mineral composition of this group, even in contiguous districts, is very great; and on comparing the atherfield beds with corresponding strata at hythe in kent, distant miles, the whole series has lost half its thickness, and presents a very dissimilar aspect.[ -a] on the other hand, professor e. forbes has shown that when the sixty-three strata at atherfield are severally examined, the total thickness of which he gives as feet, there are some fossils which range through the whole series, others which are peculiar to particular divisions. as a proof that all belong chronologically to one system, he states that whenever similar conditions are repeated in overlying strata the same species reappear. changes of depth, or of the mineral nature of the bottom, the presence or absence of lime or of peroxide of iron, the occurrence of a muddy, or a sandy, or a gravelly bottom, are marked by the banishment of certain species and the predominance of others. but these differences of conditions being mineral, chemical, and local in their nature, have nothing to do with the extinction, throughout a large area, of certain animals or plants. the rule laid down by this eminent naturalist for enabling us to test the arrival of a new state of things in the animate world, is the representation by new and different species of corresponding genera of mollusca or other beings. when the forms proper to loose sand or soft clay, or a stony or calcareous bottom, or a moderate or a great depth of water, recur with all the same species, the interval of time has been, geologically speaking, small, however dense the mass of matter accumulated. but if, the genera remaining the same, the species are changed, we have entered upon a new period; and no similarity of climate, or of geographical and local conditions, can then recall the old species which a long series of destructive causes in the animate and inanimate world has gradually annihilated. on passing from the lower greensand to the gault, we suddenly reach one of these new epochs, scarcely any of the fossil species being common to the lower and upper cretaceous systems, a break in the chain implying no doubt many missing links in the series of geological monuments which we may some day be able to supply. one of the largest and most abundant shells in the lowest strata of the lower greensand, as displayed in the atherfield section, is the large _perna mulleti_ of which a reduced figure is here given (fig. .). [illustration: fig. . _perna mulleti._ desh. in leym. _a._ exterior. _b._ hinge of upper valve.] in the south of england, during the accumulation of the lower greensand above described, the bed of the sea appears to have been continually sinking, from the commencement of the period, when the freshwater wealden beds were submerged, to the deposition of those strata on which the gault immediately reposes. pebbles of quartzose sandstone, jasper, and flinty slate, together with grains of chlorite and mica, speak plainly of the nature of the pre-existing rocks, from the wearing down of which the greensand beds were derived. the land, consisting of such rocks, was doubtless submerged before the origin of the white chalk, as corals can only multiply in the clear waters of the sea in spaces to which no mud or sand are conveyed by currents. hippurite limestone. _difference between the chalk of the north and south of europe._--by the aid of the three tests of relative age, namely, superposition, mineral character, and fossils, the geologist has been enabled to refer to the same cretaceous period certain rocks in the north and south of europe, which differ greatly, both in their fossil contents and in their mineral composition and structure. if we attempt to trace the cretaceous deposits from england and france to the countries bordering the mediterranean, we perceive, in the first place, that the chalk and greensand in the neighbourhood of london and paris form one great continuous mass, the straits of dover being a trifling interruption, a mere valley with chalk cliffs on both sides. we then observe that the main body of the chalk which surrounds paris stretches from tours to near poitiers (see the annexed map, fig. ., in which the shaded part represents chalk). [illustration: fig. . map of south-western france.] between poitiers and la rochelle, the space marked a on the map separates two regions of chalk. this space is occupied by the oolite and certain other formations older than the chalk, and has been supposed by m. e. de beaumont to have formed an island in the cretaceous sea. south of this space we again meet with a formation which we at once recognize by its mineral character to be chalk, although there are some places where the rock becomes oolitic. the fossils are, upon the whole, very similar; especially certain species of the genera _spatangus_, _ananchytes_, _cidarites_, _nucula_, _ostrea_, _gryphæa_ (_exogyra_), _pecten_, _plagiostoma_ (_lima_), _trigonia_, _catillus_, (_inoceramus_), and _terebratula_.[ -a] but _ammonites_, as m. d'archiac observes, of which so many species are met with in the chalk of the north of france, are scarcely ever found in the southern region; while the genera _hamite_, _turrilite_, and _scaphite_, and perhaps _belemnite_, are entirely wanting. on the other hand, certain forms are common in the south which are rare or wholly unknown in the north of france. among these may be mentioned many _hippurites_, _sphærulites_, and other members of that great family of mollusca called _rudistes_ by lamarck, to which nothing analogous has been discovered in the living creation, but which is quite characteristic of rocks of the cretaceous era in the south of france, spain, sicily, greece, and other countries bordering the mediterranean. [illustration: fig. . _a._ _radiolites radiosus_, d'orb. (_hippurites_, lamk.) _b._ opercular valve of same. white chalk of france.] [illustration: fig. . _radiolites foliaceus_, d'orb. syn. _sphærulites agariciformis_, blainv. white chalk of france.] [illustration: fig. . _hippurites organisans_, desmoulins. upper chalk:--chalk marl of pyrenees?[ -a] _a._ young individual; when full grown they occur in groups adhering laterally to each other. _b._ upper side of the opercular valve, showing a reticulated structure in those parts, _b_, where the external coating is worn off. _c._ upper side of the lower and cylindrical valve. _d._ cast of the interior of the lower conical valve.] the species called _hippurites organisans_ (fig. .) is more abundant than any other in the south of europe; and the geologist should make himself well acquainted with the cast _d_, which is far more common in many compact marbles of the upper cretaceous period than the shell itself, which has often wholly disappeared. the flutings, or smooth, rounded, longitudinal ribs, representing the form of the interior, are wholly unlike the hippurite itself, and in some individuals, which attain a great size and length, are very conspicuous. between the region of chalk last mentioned in which perigueux is situated, and the pyrenees, the space b intervenes. (see map, p. .) here the tertiary strata cover, and for the most part conceal, the cretaceous rocks, except in some spots where they have been laid open by the denudation of newer formations. in these places they are seen still preserving the form of a white chalky rock, which is charged in part with grains of green sand. even as far south as tercis, on the adour, near dax, where i examined them in , the cretaceous rocks retain this character. in that region m. grateloup has found in them _ananchytes ovata_ (fig. .), and other fossils of the english chalk, together with _hippurites_. flora of the cretaceous period. although the fossil plants of the cretaceous era at present known are few in number, the rocks being principally marine, they suffice, according to m. ad. brongniart, to show a transition character between the vegetation of the secondary and that of the tertiary formations. the tertiary strata, when compared to the older rocks, are marked by the predominance of _exogens_, which now constitute three-fourths of the living plants of the globe.[ -a] these exogens are wanting in the secondary strata generally, but in the cretaceous period they equal in number the _gymnogens_ (_coniferæ_ and _cycadeæ_) which abounded so much in the preceding oolitic period, and disappeared before the eocene rocks were formed.[ -b] the discovery of a tree-fern in the ferruginous sands of the lower cretaceous group of the department of ardennes in france is one of many signs of the contrast of the flora, and doubtless of the climate, of this era with that of the pliocene and modern periods. cretaceous rocks in the united states. if we pass to the american continent, we find in the state of new jersey a series of sandy and argillaceous beds wholly unlike our upper cretaceous system; which we can, nevertheless, recognize as referable, paleontologically, to the same division. that they were about the same age generally as the european chalk and greensand, was the conclusion to which dr. morton and mr. conrad came after their investigation of the fossils in . the strata consist chiefly of greensand and green marl, with an overlying coralline limestone of a pale yellow colour, and the fossils, on the whole, agree most nearly with those of the upper european series, from the maestricht beds to the gault inclusive. i collected sixty shells from the new jersey deposits in ; five of which were identical with european species--_ostrea larva_, _o. vesicularis_, _gryphæa costata_, _pecten quinque-costatus_, _belemnites mucronatus_. as some of these have the greatest vertical range in europe, they might be expected more than any others to recur in distant parts of the globe. even where the species are different, the generic forms, such as the baculite and certain sections of ammonites, as also the inoceramus (see above, fig. .) and other bivalves, have a decidedly cretaceous aspect. fifteen out of the sixty shells above alluded to, were regarded by professor forbes as good geographical representatives of well-known cretaceous fossils of europe. the correspondence, therefore, is not small, when we reflect that the part of the united states where these strata occur is between and miles distant from the chalk of central and northern europe, and that there is a difference of ten degrees in the latitude of the places compared on opposite sides of the atlantic.[ -a] fish of the genera _lamna_, _galeus_, and _carcharias_ are common to new jersey and the european cretaceous rocks. so also is the genus _mosasaurus_ among reptiles, and _pliosaurus_ (owen), another saurian likewise obtained from the english chalk. from new jersey the cretaceous formation extends southwards to north carolina, georgia, and alabama, cropping out at intervals from beneath the tertiary strata, between the appalachian mountains and the atlantic. they then sweep round the southern extremity of that chain, and stretch northwards again to tennessee and kentucky. they have also been traced far up the valley of the missouri english miles above its mouth, to the neighbourhood of fort leavenworth; and southwards to texas, according to the observations of ferdinand römer; so that already the area which they are ascertained to occupy in north america may perhaps equal their extent in europe. so little do they resemble mineralogically the european white chalk, that limestone in north america is, upon the whole, an exception to the rule; and, even in alabama, where i saw a calcareous member of this group, the marlstones are much more like the english and french lias than any other secondary deposit of the old world. at the base of the system in alabama i found dense masses of shingle, perfectly loose and unconsolidated, derived from the waste of paleozoic (or carboniferous) rocks, a mass in no way distinguishable, except by its position, from ordinary alluvium, but covered with marls abounding in inocerami. in texas, according to f. römer, the chalk assumes a new lithological type, a large portion of it consisting of hard siliceous limestone, but the organic remains leaving no doubt in regard to its age. in south america the cretaceous strata have been discovered in columbia, as at bogota and elsewhere, containing ammonites, hamites, inocerami, and other characteristic shells.[ -a] in the south of india, also, at pondicherry, verdachellum, and trinconopoly, messrs. kaye and egerton have collected fossils belonging to the cretaceous system. taken in connection with those from the united states they prove, says prof. e. forbes, that those powerful causes which stamped a peculiar character on the forms of marine animal life at this period, exerted their full intensity through the indian, european, and american seas.[ -b] here, as in north and south america, the cretaceous character can be recognized even where there is no specific identity in the fossils; and the same may be said of the organic type of those rocks in europe and india which succeed next in the ascending and descending order, the eocene and the oolitic. footnotes: [ -a] m. alcide d'orbigny, in his valuable work entitled paléontologie française, has adopted new terms for the french subdivisions of the cretaceous series, which, so far as they can be made to tally with english equivalents, seem explicable thus: danien. maestricht beds. senonien. upper and lower white chalk, and chalk marl. turonien. part of the chalk marl and the upper greensand, the latter being in his last work (cours elémentaire) termed cénomanien. albien. gault. aptien. upper part of lower greensand. neocomien. lower part of same. [ -a] see paper by the author, trans. of geol. soc., vol. v. p. ., . [ -b] fitton, geol. trans., d series, vol. iv. p. . [ -a] proceedings of geol. soc., vol. iii. pp. , ., . [ -a] geol. trans. second series, vol. iii. p. . plate . figs. . and . [ -b] geol. of u. s. exploring exped. p. . . [ -a] see chapters x. and xi. [ -b] darwin, p. . kotzebue's first voyage, vol. iii. p. . [ -c] mantell, geol. of s. e. of england, p. . [ -a] dr. fitton, quart. geol. journ., vol. i. p. ., ii. p. ., and iii. p. ., where comparative sections and a valuable table showing the vertical range of the various fossils of the lower greensand at atherfield is given. [ -a] archiac, sur la form. crétacée du s. o. de la france, mém. de la soc. géol. de france, tom. ii. [ -a] d'orbigny's paléontologie française, pl. . [ -a] in this and subsequent remarks on fossil plants i shall often use dr. lindley's terms, as most familiar in this country; but as those of m. a. brongniart are much cited, it may be useful to geologists to give a table explaining the corresponding names of groups so much spoken of in palæontology. | brongniart. | | |lindley. | | | examples. cryptogamic. | | . cryptogamous amphigens, or cellular cryptogamic. | | |thallogens. | | | |lichens, sea-weeds, fungi. | | . cryptogamous acrogens. | | |acrogens. | | | |mosses, equisetums, ferns, | | | |lycopodiums--lepidodendron. | | | | phanerogamic. | | . dicotyledonous gymnosperms. | | |gymnogens. | | | |conifers and cycads. | | . dicot. angiosperms. | | |exogens. | | | |compositæ, leguminosæ, umbelliferæ, | | | |cruciferæ, heaths, &c. all native | | | |european trees except conifers. | | . monocotyledons. | | |endogens. | | | |palms, lilies, aloes, rushes, | | | |grasses, &c. [ -b] a. brongniart, veget. foss. dict. univ., p. ., . [ -a] see a paper by the author, quart. journ. geol. soc., vol. i. p. . [ -a] proceed. geol. soc. iv. p. . [ -b] see forbes, quart. geol. journ. vol. i. p. . chapter xviii. wealden group. the wealden divisible into weald clay, hastings sand, and purbeck beds--intercalated between two marine formations--weald clay and cypris-bearing strata--iguanodon--hastings sands--fossil fish--strata formed in shallow water--brackish water-beds--upper, middle, and lower purbeck--alternations of brackish water, freshwater, and land--dirt-bed, or ancient soil--distinct species of fossils in each subdivision of the wealden--lapse of time implied--plants and insects of wealden--geographical extent of wealden--its relation to the cretaceous and oolitic periods--movements in the earth's crust to which it owed its origin and submergence. beneath the cretaceous rocks in the s.e. of england, a freshwater formation is found, called the wealden (see nos. . and . map, p. .), which, although it occupies a small horizontal area in europe, as compared to the chalk, is nevertheless of great geological interest, not only from its position, as being interpolated between two great marine formations (nos. . and . table, p. .), but also because the imbedded fossils indicate a grand succession of changes in organic life, effected during its accumulation. it is composed of three minor divisions, the weald clay, the hastings, and the purbeck beds, of which the aggregate thickness in some districts may be or feet; but which would be much more considerable (perhaps feet), were we to add together the extreme thickness acquired by each of them in their fullest development. the common name of wealden was given to the whole, because it was first studied in parts of kent, surrey, and sussex, called the weald, (see map, p. .), and we are indebted to dr. mantell for having shown in , in his geology of sussex, that the whole group was of fluviatile origin. in proof of this he called attention to the entire absence of ammonites, belemnites, terebratulæ, echinites, corals, and other marine fossils, so characteristic of the cretaceous rocks above, and of the oolitic strata below, and to the presence of paludinæ, melaniæ, and various fluviatile shells, as well as the bones of terrestrial reptiles and the trunks and leaves of land plants. [illustration: fig. . position of the wealden between two marine formations.] the evidence of so unexpected a fact as the infra-position of a dense mass of purely freshwater origin to a deep-sea deposit (a phenomenon with which we have since become familiar, in other chapters of the earth's autobiography), was received, at first, with no small doubt and incredulity. but the relative position of the beds is unequivocal; the weald clay being distinctly seen to pass beneath the greensand in various parts of surrey, kent, and sussex; and if we proceed from sussex westward to the vale of wardour, we there again observe the same formation, or, at least, the lower division of it, the purbeck, occupying the same relative position, and resting on the oolite (see fig. .). or if we pass from the base of the south downs in sussex, and cross to the isle of wight, we there again meet with the wealden series reappearing beneath the greensand, and cannot doubt that the beds are prolonged subterraneously, as indicated by the dotted lines in fig. . [illustration: fig. . cross section. o, oolite. g s, greensand, or lower cretaceous.] [illustration: fig. . cross section.] the minor groups into which the wealden has been commonly divided in england are, as before stated, three, and they succeed each other in the following descending order[ -a]:-- thickness. st. weald clay, sometimes including thin beds of sand and shelly limestone to ft. d. hastings sand, in which occur some clays and calcareous grits to ft. d. purbeck beds, consisting of various kinds of limestones and marls to ft. _weald clay._ the first division, or weald clay, is of purely freshwater origin. the uppermost beds are not only conformable, as dr. fitton observes, to the inferior strata of the lower greensand, but of similar mineral composition. to explain this, we may suppose, that as the delta of a great river was tranquilly subsiding, so as to allow the sea to encroach upon the space previously occupied by freshwater, the river still continued to carry down the same sediment into the sea. in confirmation of this view it may be stated, that the remains of the _iguanodon mantelli_, a gigantic terrestrial reptile, very characteristic of the wealden, has been discovered near maidstone, in the overlying kentish rag, or marine limestone of the lower greensand. hence we may infer that some of the saurians which inhabited the country of the great river continued to live when part of the country had become submerged beneath the sea. thus, in our own times, we may suppose the bones of large alligators to be frequently entombed in recent freshwater strata in the delta of the ganges. but if part of that delta should sink down so as to be covered by the sea, marine formations might begin to accumulate in the same space where freshwater beds had previously been formed; and yet the ganges might still pour down its turbid waters in the same direction, and carry seaward the carcasses of the same species of alligator, in which case their bones might be included in marine as well as in subjacent freshwater strata. the iguanodon, first discovered by dr. mantell, has left more of its remains in the wealden strata of the south-eastern counties, and isle of wight, than any other genus of associated saurians. it was an herbivorous reptile, and regarded by cuvier as more extraordinary than any with which he was acquainted; for the teeth, though bearing a great analogy to the modern iguanas which now frequent the tropical woods of america and the west indies, exhibit many striking and important differences (see fig. .). it appears that they have been worn by mastication; whereas the existing herbivorous reptiles clip and gnaw off the vegetable productions on which they feed, but do not chew them. their teeth, when worn, present an appearance of having been chipped off, and never, like the fossil teeth of the iguanodon, have a flat ground surface (see fig. .), resembling the grinders of herbivorous mammalia. dr. mantell computes that the teeth and bones of this animal which have passed under his examination during the last twenty years, must have belonged to no less than seventy-one distinct individuals; varying in age and magnitude from the reptile just burst from the egg, to one of which the femur measured inches in circumference. yet notwithstanding that the teeth were more numerous than any other bones, it is remarkable that it was not till the relics of all these individuals had been found, that a solitary example of part of a jaw-bone was obtained. more recently remains both of the upper and lower jaw have been met with in the hastings beds in tilgate forest. their size was somewhat greater than had been anticipated, and even allowing that the tail was short, which professor owen infers from the short bodies of the caudal vertebræ, dr. mantell estimates the probable length of some of these saurians at between and feet. the largest femur yet found measures feet inches in length, the circumference of the shaft being inches, and round the condyles inches. [ illustrations: teeth of iguanodon. fig. . partially worn tooth of a young animal. (mantell.) fig. . crown of tooth in adult, worn down. (mantell.)] occasionally bands of limestone, called sussex marble, occur in the weald clay, almost entirely composed of a species of _paludina_, closely resembling the common _p. vivipara_ of english rivers. [illustration: fig. . _cypris spinigera_, fitton.] [illustration: fig. . _cypris valdensis_, fitton. (_c. faba_, min. con. .)] [illustration: fig. . _cypris tuberculata_, fitton.] [illustration: fig. . sample with lamination.] shells of the _cypris_, an animal belonging to the crustacea, and before mentioned (p. .) as abounding in lakes and ponds, are also plentifully scattered through the clays of the wealden, sometimes producing, like the plates of mica, a thin lamination (see fig. .). similar cypriferous marls are found in the lacustrine tertiary beds of auvergne (see above, p. .). _hastings sands._ this middle division of the wealden consists of sand, calciferous grit, clay, and shale; the argillaceous strata, notwithstanding the name, being nearly in the same proportion as the arenaceous. the calcareous sandstone and grit of tilgate forest, near cuckfield, in which the remains of the iguanodon and hyleosaurus were first found, constitute an upper member of this formation. the white "sand-rock" of the hastings cliffs, about feet thick, is one of the lower members of the same. the reptiles, which are very abundant in it, consist partly of saurians, already referred by owen and mantell to eight genera, among which, besides those already enumerated, we find the megalosaurus and plesiosaurus. the pterodactyl, also a flying reptile, is met with in the same strata, and many remains of testudinata of the genera _trionyx_ and _emys_, now confined to tropical regions. [illustration: fig. . _lepidotus mantelli_, agass. wealden. _a._ palate and teeth. _b._ side view of teeth. _c._ scale.] the fishes of the wealden belong partly to the genera _pycnodus_ and _hybodus_ (see figure of genus in chap. xxi.), forms common to the wealden and oolite; but the teeth and scales of a species of _lepidotus_ are most widely diffused (see fig. .). the general form of these fish was that of the carp tribe, although perfectly distinct in anatomical character, and more allied to the pike. the whole body was covered with large rhomboidal scales, very thick, and having the exposed part covered with enamel. most of the species of this genus are supposed to have been either river fish, or inhabitants of the coasts, having not sufficient powers of swimming to advance into the deep sea. [illustration: fig. . _corbula alata_, fitton. magnified.] the shells of the hastings beds belong to the genera _melanopsis_, _melania_, _paludina_, _cyrena_, _cyclas_, _unio_, and others, which inhabit rivers or lakes; but one band has been found in dorsetshire indicating a brackish state of the water, and, in some places, even a saltness, like that of the sea, where the genera _corbula_ (see fig. .), _mytilus_, and _ostrea_ occur. at different heights in the hastings sand, in the middle of the wealden, we find again and again slabs of sandstone with a strong ripple-mark, and between these slabs beds of clay many yards thick. in some places, as at stammerham, near horsham, there are indications of this clay having been exposed so as to dry and crack before the next layer was thrown down upon it. the open cracks in the clay have served as moulds, of which casts have been taken in relief, and which are, therefore, seen on the lower surface of the sandstone (see fig. .). [illustration: fig. . underside of slab of sandstone about one yard in diameter. stammerham, sussex.] near the same place a reddish sandstone occurs in which are innumerable traces of a fossil vegetable, apparently _sphenopteris_, the stems and branches of which are disposed as if the plants were standing erect on the spot where they originally grew, the sand having been gently deposited upon and around them; and similar appearances have been remarked in other places in this formation.[ -a] in the same division also of the wealden, at cuckfield, is a bed of gravel or conglomerate, consisting of water-worn pebbles of quartz and jasper, with rolled bones of reptiles. these must have been drifted by a current, probably in water of no great depth. [illustration: fig. . _sphenopteris gracilis_ (fitton), from near tunbridge wells. _a._ portion of the same magnified.] from such facts we may infer that, notwithstanding the great thickness of this division of the wealden (and the same observation applies to the weald clay and purbeck beds), the whole of it was a deposit in water of a moderate depth, and often extremely shallow. this idea may seem startling at first, yet such would be the natural consequence of a gradual and continuous sinking of the ground in an estuary or bay, into which a great river discharged its turbid waters. by each foot of subsidence, the fundamental rock, such as the portland oolite, would be depressed one foot farther from the surface; but the bay would not be deepened, if newly deposited mud and sand should raise the bottom one foot. on the contrary, such new strata of sand and mud might be frequently laid dry at low water, or overgrown for a season by a vegetation proper to marshes. _purbeck beds._ immediately below the hastings sands we find a series of calcareous slates, marls, and limestones, called the purbeck beds, because well exposed to view in the sea-cliffs of the peninsula of purbeck, especially in durlestone bay, near swanage. they may also be advantageously studied at lulworth cove and the neighbouring bays between weymouth and dorchester. at meup's bay in particular, prof. e. forbes has recently examined minutely the organic remains of the three members of the purbeck group, displayed there in a vertical section feet thick. to the information previously supplied in the works of messrs. webster, fitton, de la beche, buckland, and mantell, he has made most ample and important additions, so that it will be desirable to give them at some length, it appearing that the upper, middle, and lower purbecks are each marked by peculiar species of organic remains, these again being different, so far as a comparison has yet been instituted, from the fossils of the overlying hastings sands and weald clay. this result cannot fail to excite much wonder, and it leads us to suspect that the wealden period, which many geologists have scarcely deigned to notice in their classification, may comprehend the history of a lapse of time as great as that of the oolitic or cretaceous eras respectively.[ -a] _upper purbeck._--the highest of the three divisions is purely freshwater, the strata, about feet in thickness, containing shells of the genera _paludina_, _physa_, _lymnea_, _planorbis_, _valvata_, _cyclas_, and _unio_, with cyprides, and fish. _middle purbeck._--to these succeed the middle purbeck, about feet thick, the uppermost part of which consists of freshwater limestone, with cyprides, turtles, and fish of different species from those in the preceding strata. below the limestone are brackish-water beds full of _cyrena_, and traversed by bands abounding in _corvulæ_ and _melaniæ_. these are based on a purely marine deposit, with _pecten_, _modiola_, _avicula_, and _thracia_, all undescribed shells. below this, again, come limestones and shales, partly of brackish and partly of freshwater origin, in which many fish, especially species of _lepidotus_ and _microdon radiatus_, are found, and a reptile named _macrorhyncus_. among the mollusks, a remarkable ribbed _melania_, of the section _chilira_, occurs. immediately below is the great and conspicuous stratum, feet thick, long familiar to geologists under the local name of "cinder-bed," formed of a vast accumulation of shells of _ostrea distorta_ (fig. .). in the uppermost part of this bed mr. forbes discovered the first echinoderm as yet known in the purbeck series, a species of _hemicidaris_, a genus characteristic of the oolitic period. it was accompanied by a species of _perna_. below the cinder-bed freshwater strata are again seen, filled in many places with species of _cypris_, _valvata_, _paludina_, _planorbis_, _lymnea_, _physa_, and _cyclas_, all different from any we had previously seen above. thick siliceous beds of chert, filled with these fossils, occur in a beautiful state of preservation, often converted into chalcedony. among these mr. forbes met with gyrogonites (the spore vesicles of _charæ_), plants never before discovered in rocks older than the eocene. again, beneath these freshwater strata, a very thin band of greenish shales, with marine shells and impressions of leaves, like those of a large _zostera_, succeeds, forming the base of the middle purbeck. [illustration: fig. . ostrea distorta. cinder-bed.] _lower purbeck._--beneath the thin marine band last mentioned, purely freshwater marls occur, containing species of _cypris_, _valvata_, and _lymnea_, different from those of the middle purbeck. this is the beginning of the inferior division, which is about feet thick. below the marls are seen more than feet of brackish-water beds, at meup's bay, abounding in a species of _serpula_, allied to, if not identical with, _serpula coacervites_, found in the wealden of hanover. there are also shells of the genus _rissoa_ (of the subgenus _hydrobia_), and a little _cardium_ of the subgenus _protocardium_, in the same beds, together with _cypris_. some of the cypris-bearing shales are strangely contorted and broken up, at the west end of the isle of purbeck. the great dirt-bed or vegetable soil containing the roots and stools of _cycadeæ_, which i shall presently describe, underlies these marls, resting upon the lowest freshwater limestone, a rock about feet thick, containing _cyclades_, _valvata_, and _lymnea_, of the same species as those of the uppermost part of the lower purbeck. this rock rests upon the top beds of the portland stone, which is purely marine, and between which and the purbecks there is no passage. the most remarkable of all the varied successions of beds enumerated in the above list, is that called by the quarrymen "the dirt," or "black dirt," which was evidently an ancient vegetable soil. it is from to inches thick, is of a dark brown or black colour, and contains a large proportion of earthy lignite. through it are dispersed rounded fragments of stone, from to inches in diameter, in such numbers that it almost deserves the name of gravel. many silicified trunks of coniferous trees, and the remains of plants allied to _zamia_ and _cycas_, are buried in this dirt-bed (see figure of living _zamia_, fig. .). these plants must have become fossil on the spots where they grew. the stumps of the trees stand erect for a height of from to feet, and even in one instance to feet, with their roots attached to the soil at about the same distances from one another as the trees in a modern forest.[ -a] the carbonaceous matter is most abundant immediately around the stumps, and round the remains of fossil _cycadeæ_.[ -b] [illustration: fig. . zamia spiralis; southern australia.[ -c]] besides the upright stumps above mentioned, the dirt-bed contains the stems of silicified trees laid prostrate. these are partly sunk into the black earth, and partly enveloped by a calcareous slate which covers the dirt-bed. the fragments of the prostrate trees are rarely more than or feet in length; but by joining many of them together, trunks have been restored, having a length from the root to the branches of from to feet, the stems being undivided for or feet, and then forked. the diameter of these near the roots is about foot.[ -d] root-shaped cavities were observed by professor henslow to descend from the bottom of the dirt-bed into the subjacent freshwater stone, which, though now solid, must have been in a soft and penetrable state when the trees grew.[ -e] [illustration: fig. . section in isle of portland, dorset. (buckland and de la beche.)] the thin layers of calcareous slate (fig. .) were evidently deposited tranquilly, and would have been horizontal but for the protrusion of the stumps of the trees, around the top of each of which they form hemispherical concretions. the dirt-bed is by no means confined to the island of portland, where it has been most carefully studied, but is seen in the same relative position in the cliffs east of lulworth cove, in dorsetshire, where, as the strata have been disturbed, and are now inclined at an angle of °, the stumps of the trees are also inclined at the same angle in an opposite direction--a beautiful illustration of a change in the position of beds originally horizontal (see fig. .). traces of the dirt-bed have also been observed by dr. buckland, about two miles north of thame, in oxfordshire; and by dr. fitton, in the cliffs of the boulonnois, on the french coast; but, as might be expected, this freshwater deposit is of limited extent when compared to most marine formations. [illustration: fig. . section in cliff east of lulworth cove. (buckland and de la beche.)] from the facts above described, we may infer, first, that the superior beds of the oolite, called "the portland," which are full of marine shells, were overspread with fluviatile mud, which became dry land, and covered by a forest, throughout a portion of the space now occupied by the south of england, the climate being such as to admit the growth of the _zamia_ and _cycas_. dly. this land at length sank down and was submerged with its forests beneath a body of fresh water, from which sediment was thrown down enveloping fluviatile shells. dly. the regular and uniform preservation of this thin bed of black earth over a distance of many miles, shows that the change from dry land to the state of a freshwater lake or estuary, was not accompanied by any violent denudation, or rush of water, since the loose black earth, together with the trees which lay prostrate on its surface, must inevitably have been swept away had any such violent catastrophe then taken place. the dirt-bed has been described above in its most simple form, but in some sections the appearances are more complicated. the forest of the dirt-bed was not everywhere the first vegetation which grew in this region. two other beds of carbonaceous clay, one of them containing _cycadeæ_, in an upright position, have been found below it, and one above it[ -a], which implies other oscillations in the level of the same ground, and its alternate occupation by land and water more than once. _table showing the changes of medium in which the strata were formed, from the lower greensand to the portland stone inclusive, in the south-east of england._ . marine lower greensand. . freshwater weald clay. . freshwater } brackish } hastings sand. freshwater } . freshwater upper purbeck. . freshwater } brackish } marine } brackish } middle purbeck. marine } freshwater } marine } . freshwater } brackish } land } freshwater } land (dirt-bed) } lower purbeck. freshwater } land } freshwater } land } freshwater } . marine portland stone. the annexed tabular view will enable the reader to take in at a glance the successive changes from sea to river, and from river to sea, or from these again to a state of land, which have occurred in this part of england between the cretaceous and oolitic periods. that there have been at least four changes in the species of testacea during the deposition of the wealden, seems to follow from the observations recently made by professor e. forbes, so that, should we hereafter find the signs of many more alternate occupations of the same area by different elements, it is no more than we might expect. even during a small part of a zoological period, not sufficient to allow time for many species to die out, we find that the same area has been laid dry, and then submerged, and then again laid dry, as in the deltas of the po and ganges, the history of which has been brought to light by artesian borings.[ -a] we also know that similar revolutions have occurred within the present century ( ) in the delta of the indus in cutch[ -b], where land has been laid permanently under the waters both of the river and sea, without its soil or shrubs having been swept away. even, independently of any vertical movements of the ground, we see in the principal deltas, such as that of the mississippi, that the sea extends its salt waters annually for many months over considerable spaces, which, at other seasons, are occupied by the river during its inundations. it will be observed that the division of the purbecks into upper, middle, and lower, has been made by professor e. forbes, strictly on the principle of the entire distinctness of the species of organic remains which they include. the lines of demarcation are not lines of disturbance, nor indicated by any striking physical characters or mineral changes. the features which attract the eye in the purbecks, such as the dirt-beds, the dislocated strata at lulworth, and the cinder-bed, do not indicate any breaks in the distribution of organized beings. "the causes which led to a complete change of life three times during the deposition of the freshwater and brackish strata must," says this naturalist, "be sought for, not simply in either a rapid or a sudden change of their area into land or sea, but in the great lapse of time which intervened between the epochs of deposition at certain periods during their formation." each dirt-bed may, no doubt, be the memorial of many thousand years or centuries, because we find that or feet of vegetable soil is the only monument which many a tropical forest has left of its existence ever since the ground on which it now stands was first covered with its shade. yet, even if we imagined the fossil soils of the lower purbeck to represent as many ages, we need not expect on that account to find them constituting the lines of separation between successive strata characterized by different zoological types. the preservation of a layer of vegetable soil, when in the act of being submerged, must be regarded as a rare exception to a general rule. it is of so perishable a nature, that it must usually be carried away by the denuding waves or currents of the sea or by a river; and many dirt-beds were probably formed in succession, and annihilated in the wealden, besides those few which now remain. [illustration: fig. . cone from the isle of purbeck, resembling the _dammara_ of the moluccas. (fitton.)] the plants of the wealden, so far as our knowledge extends at present, consist chiefly of ferns, coniferæ (see fig. .), and cycadeæ, without any exogens; the whole more allied to the oolitic than to the cretaceous vegetation, although some of the species seem to be common to the chalk. but the vertebrate and invertebrate animals indicate, in like manner, a relationship to both these periods, though a nearer affinity to the oolitic. mr. brodie has found the remains of beetles and several insects of the homopterous and trichopterous orders, some of which now live on plants, like those of the wealden, while others hover over the surface of our present rivers. but no bones of mammalia have been met with among those of land-reptiles. yet, as the reader will learn, in chapter xx., that the relics of marsupial quadrupeds have been detected in still older beds, and, as it was so long before a single portion of the jaw of an iguanodon was met with in the tilgate quarries (see p. .), we need by no means despair of discovering hereafter some evidence of the existence of warm-blooded quadrupeds at this era. it is, at least, too soon to infer, on mere negative evidence, that the mammalia were foreign to this fauna. in regard to the geographical extent of the wealden, it cannot be accurately laid down; because so much of it is concealed beneath the newer marine formations. it has been traced about english miles from west to east, from lulworth cove to near boulogne, in france; and about miles from north-west to south-east, from whitchurch, in buckinghamshire, to beauvais, in france. if the formation be continuous throughout this space, which is very doubtful, it does not follow that the whole was contemporaneous; because, in all likelihood, the physical geography of the region underwent frequent change throughout the whole period, and the estuary may have altered its form, and even shifted its place. dr. dunker, of cassel, and h. von meyer, in an excellent monograph on the wealdens of hanover and westphalia, have shown that they correspond so closely, not only in their fossils, but also in their mineral characters, with the english series, that we can scarcely hesitate to refer the whole to one great delta. even then, the magnitude of the deposit may not exceed that of many modern rivers. thus, the delta of the quorra or niger, in africa, stretches into the interior for more than miles, and occupies, it is supposed, a space of more than miles along the coast, thus forming a surface of more than , square miles, or equal to about one half of england.[ -a] besides, we know not, in such cases, how far the fluviatile sediment and organic remains of the river and the land may be carried out from the coast, and spread over the bed of the sea. i have shown, when treating of the mississippi, that a more ancient delta, including species of shells, such as now inhabit louisiana, has been upraised, and made to occupy a wide geographical area, while a newer delta is forming[ -b]; and the possibility of such movements, and their effects, must not be lost sight of when we speculate on the origin of the wealden. if it be asked where the continent was placed from the ruins of which the wealden strata were derived, and by the drainage of which a great river was fed, we are half tempted to speculate on the former existence of the atlantis of plato. the story of the submergence of an ancient continent, however fabulous in history, must have been true again and again as a geological event. the real difficulty consists in the persistence of a large hydrographical basin, from whence a great body of fresh water was poured into the sea, precisely at a period when the neighbouring area of the wealden was gradually going downwards feet or more perpendicularly. if the adjoining land participated in the movement, how could it escape being submerged, or how could it retain its size and altitude so as to continue to be the source of such an inexhaustible supply of fresh water and sediment? in answer to this question, we are fairly entitled to suggest that the neighbouring land may have been stationary, or may even have undergone a contemporaneous slow upheaval. there may have been an ascending movement in one region, and a descending one in a contiguous parallel zone of country; just as the northern part of scandinavia is now rising, while the middle portion (that south of stockholm) is unmoved, and the southern extremity in scania is sinking, or at least has sunk within the historical period.[ -c] we must, nevertheless, conclude, if we adopt the above hypothesis, that the depression of the land became general throughout a large part of europe at the close of the wealden period, a subsidence which brought in the cretaceous ocean. footnotes: [ -a] dr. fitton, geol. trans. vol. iv. p. . second series. [ -a] mantell, geol. of s. e. of england, p. . [ -a] "on the dorsetshire purbecks," by prof. e. forbes, edinb. brit. assoc., aug. . [ -a] mr. webster first noticed the erect position of the trees and described the dirt-bed. [ -b] fitton, geol. trans., second series, vol. iv. pp. , . [ -c] see flinders' voyage. [ -d] fitton, ibid. [ -e] buckland and de la beche, geol. trans., second series, vol. iv. p. . mr. forbes has ascertained that the subjacent rock is a freshwater limestone, and not a portion of the portland oolite, as was previously imagined. [ -a] e. forbes, ibid. [ -a] see principles of geol., th ed. pp. - . [ -b] ibid. p. . [ -a] fitton, geol. of hastings, p. .; who cites lander's travels. [ -b] see above, p. .; and second visit to the u. s. vol. ii. chap. xxxiv. [ -c] see the author's anniv. address, geol. soc. , quart. geol. journ. vol. vi. p. . chapter xix. denudation of the chalk and wealden. physical geography of certain districts composed of cretaceous and wealden strata--lines of inland chalk-cliffs on the seine in normandy--outstanding pillars and needles of chalk--denudation of the chalk and wealden in surrey, kent, and sussex--chalk once continuous from the north to the south downs--anticlinal axis and parallel ridges--longitudinal and transverse valleys--chalk escarpments--rise and denudation of the strata gradual--ridges formed by harder, valleys by softer beds--why no alluvium, or wreck of the chalk, in the central district of the weald--at what periods the weald valley was denuded--land has most prevailed where denudation has been greatest--elephant bed, brighton. all the fossiliferous formations may be studied by the geologist in two distinct points of view: first, in reference to their position in the series, their mineral character and fossils; and, secondly, in regard to their physical geography, or the manner in which they now enter, as mineral masses, into the external structure of the earth; forming the bed of lakes and seas, or the surface and foundation of hills and valleys, plains and table-lands. some account has already been given on the first head of the tertiary, the cretaceous, and wealden strata; and we may now proceed to consider certain features in the physical geography of these groups as they occur in parts of england and france. the hills composed of white chalk in the s.e. of england have a smooth rounded outline, and being usually in the state of sheep pastures, are free from trees or hedgerows; so that we have an opportunity of observing how the valleys by which they are drained ramify in all directions, and become wider and deeper as they descend. although these valleys are now for the most part dry, except during heavy rains and the melting of snow, they may have been due to aqueous denudation, as explained in the sixth chapter; having been excavated when the chalk emerged gradually from the sea. this opinion is confirmed by the occasional occurrence of long lines of inland cliffs, in which the strata are cut off abruptly in steep and often vertical precipices. the true nature of such escarpments is nowhere more obvious than in parts of normandy, where the river seine and its tributaries flow through deep winding valleys, hollowed out of chalk horizontally stratified. thus, for example, if we follow the seine for a distance of about miles from andelys to elboeuf, we find the valley flanked on both sides by a deep slope of chalk, with numerous beds of flint, the formation being laid open for a thickness of about and feet. above the chalk is an overlying mass of sand, gravel, and clay, from to feet thick. the two opposite slopes of the hills _a_ and _b_, where the chalk appears at the surface, are from to miles apart, and they are often perfectly smooth and even, like the steepest of our downs in england; but at many points they are broken by one, two, or more ranges of vertical and even overhanging cliffs of bare white chalk with flints. at some points detached needles and pinnacles stand in the line of the cliffs, or in front of them, as at _c_, fig. . on the right bank of the seine, at andelys, one range, about miles long, is seen varying from to feet in perpendicular height, and having its continuity broken by a number of dry valleys or coombs, in one of which occurs a detached rock or needle, called the tête d'homme (see figs. , .). the top of this rock presents a precipitous face towards every point of the compass; its vertical height being more than feet on the side of the downs, and towards the seine, the average diameter of the pillar being feet. its composition is the same as that of the larger cliffs in its neighbourhood, namely, white chalk, having occasionally a crystalline texture like marble, with layers of flint in nodules and tabular masses. the flinty beds often project in relief or feet beyond the white chalk, which is generally in a state of slow decomposition, either exfoliating or being covered with white powder, like the chalk cliffs on the english coast; and, as in them, this superficial powder contains in some places common salt. [illustration: fig. . section across valley of seine.] [illustration: fig. . view of the tête d'homme, andelys, seen from above.] other cliffs are situated on the right bank of the seine, opposite tournedos, between andelys and pont de l'arche, where the precipices are from to feet high: several of their summits terminate in pinnacles; and one of them, in particular, is so completely detached as to present a perpendicular face feet high towards the sloping down. on these cliffs several ledges are seen, which mark so many levels at which the waves of the sea may be supposed to have encroached for a long period. at a still greater height, immediately above the top of this range, are three much smaller cliffs, each about feet high, with as many intervening terraces, which are continued so as to sweep in a semicircular form round an adjoining coomb, like those in sicily before described (p. .). [illustration: fig. . side view of the tête d'homme. white chalk with flints.] [illustration: fig. . chalk pinnacle at senneville.] [illustration: fig. . roches d'orival, elboeuf.] if we then descend the river from vatteville to a place called senneville, we meet with a singular needle about feet high, perfectly isolated on the escarpment of chalk on the right bank of the seine (see fig. .). another conspicuous range of inland cliffs is situated about miles below on the left bank of the seine, beginning at elboeuf, and comprehending the roches d'orival (see fig. .). like those before described, it has an irregular surface, often overhanging, and with beds of flint projecting several feet. like them, also, it exhibits a white powdery surface, and consists entirely of horizontal chalk with flints. it is miles inland, its height, in some parts, exceeding feet, and its base only a few feet above the level of the seine. it is broken, in one place, by a pyramidal mass or needle, feet high, called the roche de pignon, which stands out about feet in front of the upper portion of the main cliffs, with which it is united by a narrow ridge about feet lower than its summit (see fig. .). like the detached rocks before mentioned at senneville, vatteville, and andelys, it may be compared to those needles of chalk which occur on the coast of normandy, as well as in the isle of wight and in purbeck[ -a] (see fig. .). [illustration: fig. . view of the roche de pignon, seen from the south.] [illustration: fig. . needle and arch of etretat, in the chalk cliffs of normandy. height of arch feet. (passy.)[ -b]] the foregoing description and drawings will show, that the evidence of certain escarpments of the chalk having been originally sea-cliffs, is far more full and satisfactory in france than in england. if it be asked why, in the interior of our own country, we meet with no ranges of precipices equally vertical and overhanging, and no isolated pillars or needles, we may reply that the greater hardness of the chalk in normandy may, no doubt, be the chief cause of this difference. but the frequent absence of all signs of littoral denudation in the valley of the seine itself is a negative fact of a far more striking and perplexing character. the cliffs, after being almost continuous for miles, are then wholly wanting for much greater distances, being replaced by a green sloping down, although the beds remain of the same composition, and are equally horizontal; and although we may feel assured that the manner of the upheaval of the land, whether intermittent or not, must have been the same at those intermediate points where no cliffs exist, as at others where they are so fully developed. but, in order to explain such apparent anomalies, the reader must refer again to the theory of denudation, as expounded in the th chapter; where it was shown, first, that the undermining force of the waves and marine currents varies greatly at different parts of every coast; secondly, that precipitous rocks have often decomposed and crumbled down; and thirdly, that many terraces and small cliffs may now lie concealed beneath a talus of detrital matter. _denudation of the weald valley._--no district is better fitted to illustrate the manner in which a great series of strata may have been upheaved and gradually denuded than the country intervening between the north and south downs. this region, of which a ground plan is given in the accompanying map (fig. .), comprises within it the whole of sussex, and parts of the counties of kent, surrey, and hampshire. the space in which the formations older than the white chalk, or those from the gault to the hastings sand inclusive, crop out, is bounded everywhere by a great escarpment of chalk, which is continued on the opposite side of the channel in the bas boulonnais in france, where it forms the semicircular boundary of a tract in which older strata also appear at the surface. the whole of this district may therefore be considered geologically as one and the same. [illustration: fig. . geological map of the south-east of england and part of france, exhibiting the denudation of the weald. . tertiary. . chalk and upper greensand. . gault. . lower greensand. . weald clay. . hastings sand. . purbeck beds. . oolite.] [illustration: fig. . section from the london to the hampshire basin across the valley of the weald. . tertiary strata. . chalk and firestone. . gault. . lower greensand. . weald clay. . hastings sands.] [illustration: fig. . highest point of south downs, feet. anticlinal axis of the weald. crowborough hill, feet. highest point of north downs, feet.[ -a] section of the country from the confines of the basin of london to that of hants, with the principal heights above the level of the sea on a true scale.[ -b]] the space here inclosed within the escarpment of the chalk affords an example of what has been sometimes called a "valley of elevation" (more properly "of denudation"); where the strata, partially removed by aqueous excavation, dip away on all sides from a central axis. thus, it is supposed that the area now occupied by the hastings sand (no. .) was once covered by the weald clay (no. .), and this again by the greensand (no. .), and this by the gault (no. .); and, lastly, that the chalk (no. .) extended originally over the whole space between the north and the south downs. this theory will be better understood by consulting the annexed diagram (fig. .), where the dark lines represent what now remains, and the fainter ones those portions of rock which are believed to have been carried away. at each end of the diagram the tertiary strata (no. .) are exhibited reposing on the chalk. in the middle are seen the hastings sands (no. .) forming an anticlinal axis, on each side of which the other formations are arranged with an opposite dip. it has been necessary, however, in order to give a clear view of the different formations, to exaggerate the proportional height of each in comparison to its horizontal extent; and a true scale is therefore subjoined in another diagram (fig. .), in order to correct the erroneous impression which might otherwise be made on the reader's mind. in this section the distance between the north and south downs is represented to exceed forty miles; for the valley of the weald is here intersected in its longest diameter, in the direction of a line between lewes and maidstone. through the central portion, then, of the district supposed to be denuded runs a great anticlinal line, having a direction nearly east and west, on both sides of which the beds , , , and , crop out in succession. but, although, for the sake of rendering the physical structure of this region more intelligible, the central line of elevation has alone been introduced, as in the diagrams of smith, mantell, conybeare, and others, geologists have always been well aware that numerous minor lines of dislocation and flexure run parallel to the great central axis. in the central area of the hastings sand the strata have undergone the greatest displacement; one fault being known, where the vertical shift of a bed of calcareous grit is no less than fathoms.[ -a] much of the picturesque scenery of this district arises from the depth of the narrow valleys and ridges to which the sharp bends and fractures of the strata have given rise; but it is also in part to be attributed to the excavating power exerted by water, especially on the interstratified argillaceous beds. besides the series of longitudinal valleys and ridges in the weald, there are valleys which run in a transverse direction, passing through the chalk to the basin of the thames on the one side, and to the english channel on the other. in this manner the chain of the north downs is broken by the rivers wey, mole, darent, medway, and stour; the south downs by the arun, adur, ouse, and cuckmere.[ -b] if these transverse hollows could be filled up, all the rivers, observes mr. conybeare, would be forced to take an easterly course, and to empty themselves into the sea by romney marsh and pevensey levels.[ -a] mr. martin has suggested that the great cross fractures of the chalk, which have become river channels, have a remarkable correspondence on each side of the valley of the weald; in several instances the gorges in the north and south downs appearing to be directly opposed to each other. thus, for example, the defiles of the wey in the north downs, and of the arun in the south, seemed to coincide in direction; and, in like manner, the ouse corresponds to the darent, and the cuckmere to the medway.[ -b] [illustration: fig. . view of the chalk escarpment of the south downs. taken from the devil's dike, looking towards the west and south-west. _a._ the town of steyning is hidden by this point. _b._ edburton church. _c._ road. _d._ river adur.] although these coincidences may, perhaps, be accidental, it is by no means improbable, as hinted by the author above mentioned, that great amount of elevation towards the centre of the weald district gave rise to transverse fissures. and as the longitudinal valleys were connected with that linear movement which caused the anticlinal lines running east and west, so the cross fissures might have been occasioned by the intensity of the upheaving force towards the centre of the line. but before treating of the manner in which the upheaving movement may have acted, i shall endeavour to make the reader more intimately acquainted with the leading geographical features of the district, so far as they are of geological interest. in whatever direction we travel from the tertiary strata of the basins of london and hampshire towards the valley of the weald, we first ascend a slope of white chalk, with flints, and then find ourselves on the summit of a declivity consisting, for the most part, of different members of the chalk formation; below which the upper greensand, and sometimes, also, the gault, crop out. this steep declivity is the great escarpment of the chalk before mentioned, which overhangs a valley excavated chiefly out of the argillaceous or marly bed, termed gault (no. .). the escarpment is continuous along the southern termination of the north downs, and may be traced from the sea, at folkestone, westward to guildford and the neighbourhood of petersfield, and from thence to the termination of the south downs at beachy head. in this precipice or steep slope the strata are cut off abruptly, and it is evident that they must originally have extended farther. in the woodcut (fig. . p. .), part of the escarpment of the south downs is faithfully represented, where the denudation at the base of the declivity has been somewhat more extensive than usual, in consequence of the upper and lower greensand being formed of very incoherent materials, the upper, indeed, being extremely thin and almost wanting. [illustration: fig. . chalk escarpment, as seen from the hill above steyning, sussex. the castle and village of bramber in the foreground.] the geologist cannot fail to recognize in this view the exact likeness of a sea cliff; and if he turns and looks in an opposite direction, or eastward, towards beachy head (see fig. .), he will see the same line of heights prolonged. even those who are not accustomed to speculate on the former changes which the surface has undergone may fancy the broad and level plain to resemble the flat sands which were laid dry by the receding tide, and the different projecting masses of chalk to be the headlands of a coast which separated the different bays from each other. in regard to the transverse valleys before mentioned, as intersecting the chalk hills, some idea of them may be derived from the subjoined sketch (fig. .), of the gorge of the river adur, taken from the summit of the chalk downs, at a point in the bridle-way leading from the towns of bramber and steyning to shoreham. if the reader will refer again to the view given in a former woodcut (fig. . p. .), he will there see the exact point where the gorge of which i am now speaking interrupts the chalk escarpment. a projecting hill, at the point _a_, hides the town of steyning, near which the valley commences where the adur passes directly to the sea at old shoreham. the river flows through a nearly level plain, as do most of the others which intersect the hills of surrey, kent, and sussex; and it is evident that these openings, so far at least as they are due to aqueous erosion, have not been produced by the rivers, many of which, like the ouse near lewes, have filled up arms of the sea, instead of deepening the hollows which they traverse. [illustration: fig. . transverse valley of the adur in the south downs. _a._ town of steyning. _b._ river adur. _c._ old shoreham.] now, in order to account for the manner in which the five groups of strata, , , , , , represented in the map, fig. . and in the section fig. ., may have been brought into their present position, the following hypothesis has been very generally adopted:--suppose the five formations to lie in horizontal stratification at the bottom of the sea; then let a movement from below press them upwards into the form of a flattened dome, and let the crown of this dome be afterwards cut off, so that the incision should penetrate to the lowest of the five groups. the different beds would then be exposed on the surface, in the manner exhibited in the map, fig. .[ -a] the quantity of denudation or removal by water of stratified masses assumed to have once reached continuously from the north to the south downs is so enormous, that the reader may at first be startled by the boldness of the hypothesis. but the difficulty vanishes when once sufficient time is allowed for the gradual and successive rise of the strata, during which the waves and currents of the ocean might slowly accomplish an operation, which no sudden diluvial rush of waters could possibly have effected. among other proofs of the action of water, it may be stated that the great longitudinal valleys follow the outcrop of the softer and more incoherent beds, while ridges or lines of cliff usually occur at those points where the strata are composed of harder stone. thus, for example, the chalk with flints, together with the subjacent upper greensand, which is often used for building, under the provincial name of "firestone," has been cut into a steep cliff on that side on which the sea encroached. this escarpment bounds a deep valley, excavated chiefly out of the soft argillaceous or marly bed, termed gault (no. .). in some places the upper greensand is in a loose and incoherent state, and there it has been as much denuded as the gault; as, for example, near beachy head; but farther to the westward it is of great thickness, and contains hard beds of blue chert and calcareous sandstone or firestone. here, accordingly, we find that it produces a corresponding influence on the scenery of the country; for it runs out like a step beyond the foot of the chalk-hills, and constitutes a lower terrace, varying in breadth from a quarter of a mile to three miles, and following the sinuosities of the chalk escarpment.[ -a] [illustration: fig. . cross section. _a._ chalk with flints. _b._ chalk without flints. _c._ upper greensand, or firestone. _d._ gault.] it is impossible to desire a more satisfactory proof that the escarpment is due to the excavating power of water during the rise of the strata; for i have shown, in my account of the coast of sicily, in what manner the encroachments of the sea tend to efface that succession of terraces which must otherwise result from the intermittent upheaval of a coast preyed upon by the waves.[ -b] during the interval between two elevatory movements, the lower terrace will usually be destroyed, wherever it is composed of incoherent materials; whereas the sea will not have time entirely to sweep away another part of the same terrace, or lower platform, which happens to be composed of rocks of a harder texture, and capable of offering a firmer resistance to the erosive action of water. as the yielding clay termed gault would be readily washed away, we find its outcrop marked everywhere by a valley which skirts the base of the chalk hills, and which is usually bounded on the opposite side by the lower greensand; but as the upper beds of this last formation are most commonly loose and incoherent, they also have usually disappeared and increased the breadth of the valley. but in those districts where chert, limestone, and other solid materials enter largely into the composition of this formation (no. .), they give rise to a range of hills parallel to the chalk, which sometimes rival the escarpment of the chalk itself in height, or even surpass it, as in leith hill, near dorking. this ridge often presents a steep escarpment towards the soft argillaceous deposit called the weald clay (no. .; see the strong lines in fig. . p. .), which usually forms a broad valley, separating the lower greensand from the hastings sands or forest ridge; but where subordinate beds of sandstone of a firmer texture occur, the uniformity of the plain of no. . is broken by waving irregularities and hillocks. it will be easy to show how closely the superficial inequalities agree with those which we might naturally expect to originate during the gradual rise of the wealden district. suppose the line of the most energetic movement to have coincided with what is now the central ridge of the weald valley; in that case the first land which emerged must have been situated where the forest ridge is now placed. here many shoals and reefs may first have existed, and islands of chalk devoured in the course of ages by the ocean (see fig. .); so that the top of the shattered dome which first appeared above water may have been utterly destroyed, and the masses represented by the fainter lines (fig. .) removed. [ illustrations: fig. ., fig. . the dotted lines represent the sea-level.] the upper greensand is represented (fig. .) as forming on the left hand a single precipice with the chalk; while on the right there are two cliffs, with an intervening terrace, as before described in fig. . two strips of land would then remain on each side of a channel, presenting ranges of white cliffs facing each other. a powerful current might then scoop out a channel in the gault (no. .). this softer bed would yield with ease in proportion as parts of it were brought up from time to time and exposed to the fury of the waves, so that large spaces occupied by the harder formation or greensand (no. .) would be laid bare. this last rock, opposing a more effectual resistance, would next emerge; while the chalk cliffs, at the base of which the gault is rapidly undermined, would recede farther from each other, after which four parallel strips of land, or rows of islands, would be caused, which are represented by the masses which in fig. . rise above the dotted line indicating the sea-level. in this diagram, however, the inclination of the upper surface of the formations (nos. . and .), is exaggerated. originally this surface must have been level, like the submarine terraces produced by denudation, and described before (p. . and .); but they were afterwards more and more tilted by that general movement to which the region of the weald owes its structure. at length, by the farther elevation of the dome-shaped mass, the clay (no. .) would be brought within reach of the waves, which would probably gain the more easy access to the subjacent deposit by the rents which would be caused in no. ., and in the central part of the ridge where the uplifting force had been exerted with the greatest energy. the opposite cliffs, in which the greensand (no. .) terminates, would now begin to recede from each other, having at their base a yielding stratum of clay (no. .). lastly, the sea would penetrate to the sand (no. .), and then the state of things indicated in the dark lines of the upper section (fig. .), would be consummated. [illustration: fig. . the coomb, near lewes.] it was stated that there are many lines of flexure and dislocation, running east and west, or parallel to the central axis of the wealden. they are numerous in the district of the hastings sand, and sometimes occur in the chalk itself. one of the latter kind has given rise to the ravine called the coomb, near lewes, and was first traced out by dr. mantell, in whose company i examined it. this coomb is seen on the eastern side of the valley of the ouse, in the suburbs of the town of lewes. the steep declivities on each side are covered with green turf, as is the bottom, which is perfectly dry. no outward signs of disturbance are visible; and the connection of the hollow with subterranean movements would not have been suspected by the geologist, had not the evidence of great convulsions been clearly exposed in the escarpment of the valley of the ouse, and the numerous chalk pits worked at the termination of the coomb. by the aid of these we discover that the ravine coincides precisely with a line of fault, on one side of which the chalk with flints (_a_, fig. .), appears at the summit of the hill, while it is thrown down to the bottom on the other. mr. martin, in his work on the geology of western sussex, published in , threw much light on the structure of the wealden by tracing out continuously for miles the direction of many anticlinal lines and cross fractures; and the same course of investigation has since been followed out in greater detail by mr. hopkins. the mathematician last-mentioned has shown that the observed direction of the lines of flexure and dislocation in the weald district coincide with those which might have been anticipated theoretically on mechanical principles, if we assume certain simple conditions under which the strata were lifted up by an expansive subterranean force. he finds by calculation that if this force was applied so as to act uniformly upwards within an elliptic area, the longitudinal fissures thereby produced would nearly coincide with the outlines of the ellipse, forming cracks, which are portions of smaller concentric ellipses, parallel to the margin of the larger one. these longitudinal fissures would also be intercepted by others running at right angles to them, and both lines of fracture may have been produced at the same time.[ -a] in this illustration it is supposed that the expansive force acted simultaneously and with equal intensity at every point within the upheaved area, and not with greater energy along the central axis or region of principal elevation. [illustration: fig. . fault in the cliff hills near lewes. mantell. _a._ chalk with flints. _b._ lower chalk.[ -b]] the geologist cannot fail to derive great advantage in his speculations from the mathematical investigation of a problem of this kind, where results free from all uncertainty are obtained on the assumption of certain simple conditions. such results, when once ascertained by mathematical methods, may serve as standard cases, to which others occurring in nature of a more complicated kind may be referred. in order that a uniform force should cause the strata to attain in the centre of the ellipse a height so far exceeding that which they have reached round the margin, it is necessary to assume that the mass of upheaved strata offered originally a very unequal degree of resistance to the subterranean force. this may have happened either from their being more fractured in one place than in another, or from being pressed down by a less weight of incumbent strata; as if we suppose, what is far from improbable, that great denudation had taken place in the middle of the wealden before the final and principal upheaval occurred. it is suggested that the beds may have been acted upon somewhat in the manner of a carpet spread out loosely on a floor, and nailed down round the edges, which would swell into the shape of a dome if pressed up equally at every point by air admitted from beneath. but when we are reasoning on the particular phenomena of the weald, we have no geological data for determining whether it be more probable that originally the resistance to be overcome was so extremely unequal in different places, or whether the subterranean force, instead of being everywhere uniform, was not applied with very different degrees of intensity beneath distinct portions of the upraised area. the opinion that both the longitudinal and transverse lines of fracture may have been produced simultaneously, accords well with that expressed by m. thurmann, in his work on the anticlinal ridges and valleys of elevation of the bernese jura.[ -a] for the accuracy of his map and sections i can vouch, from personal examination, in , of part of the region surveyed by him. among other results, at which this author arrived, it appears that the breadth of all the numerous anticlinal ridges and dome-shaped masses in the jura is invariably great in proportion to the number of the formations exposed to view; or, in other words, to the depth to which the superimposed groups of secondary strata have been laid open. (see fig. . p. . for structure of jura.) he also remarks, that the anticlinal lines are occasionally oblique and cross each other, in which case the greatest dislocation of the beds takes place. some of the cross fractures are imagined by him to have been contemporaneous, others subsequent to the longitudinal ones. i have assumed, in the former part of this chapter, that the rise of the weald was gradual, whereas many geologists have attributed its elevation to a single effort of subterranean violence. there appears to them such a unity of effect in this and other lines of deranged strata in the south-east of england, such as that of the isle of wight, as is inconsistent with the supposition of a great number of separate movements recurring after long intervals of time. but we know that earthquakes are repeated throughout a long series of ages in the same spots, like volcanic eruptions. the oldest lavas of etna were poured out many thousands, perhaps myriads of years before the newest, and yet they, and the movements accompanying their emission, have produced a symmetrical mountain; and if rivers of melted matter thus continue to flow in the same direction, and towards the same point, for an indefinite lapse of ages, what difficulty is there in conceiving that the subterranean volcanic force, occasioning the rise or fall of certain parts of the earth's crust, may, by reiterated movements, produce the most perfect unity of result? _alluvium of the weald._--our next inquiry may be directed to the alluvium strewed over the surface of the supposed area of denudation. has any wreck been left behind of the strata removed? to this we may answer, that the chalk downs even on their summits are covered every where with gravel composed of unrounded and partially rounded chalk flints, such as might remain after masses of white chalk had been softened and removed by water. this superficial accumulation of the hard or siliceous materials of the disintegrated strata may be due in some degree to pluvial action; for during extraordinary rains a rush of water charged with calcareous matter, of a milk-white colour, may be seen to descend even gently sloping hills of chalk. if a layer no thicker than the tenth of an inch be removed once in a century, a considerable mass may in the course of indefinite ages melt away, leaving nothing save a layer of flinty nodules to attest its former existence. these unrolled flints may remain mixed with others more or less rounded, which the waves left originally on the surface of the chalk, when it first emerged from the sea. a stratum of fine clay sometimes covers the surface of slight depressions and the bottom of valleys in the white chalk, which may represent the aluminous residue of the rock, after the pure carbonate of lime has been dissolved by rain water, charged with excess of carbonic acid derived from decayed vegetable matter.[ -a] although flint gravel is so abundant on the chalk itself, it is usually wanting in the deep longitudinal valleys at the foot of the chalk escarpment, although, in some few instances, the detritus of the chalk has been traced in patches over the gault, and even the lower greensand, for a distance of several miles from the escarpment of the north and south downs. but no vestige of the chalk and its flints has been seen on the central ridge of the weald or the hastings sands, but merely gravel derived from the rocks immediately subjacent. this distribution of alluvium, and especially the absence of chalk detritus in the central district, agrees well with the theory of denudation before set forth; for to return to fig. ., if the chalk (no. .) were once continuous and covered every where with flint gravel, this superficial covering would be the first to be carried away from the highest part of the dome long before any of the gault (no. .) was laid bare. now if some ruins of the chalk remain at first on the gault, these would be, in a great degree, cleared away before any part of the lower greensand (no. .) is denuded. thus in proportion to the number and thickness of the groups removed in succession, is the probability lessened of our finding any remnants of the highest group strewed over the bared surface of the lowest. as an exception to the general rule of the small distance to which any wreck of the chalk can be traced from the escarpments of the north and south downs, i may mention a thick bed of chalk flints which occurs near barcombe, about three miles to the north of lewes (see fig. .), a place which i visited with dr. mantell, to whom i am indebted for the accompanying section. even here it will be seen that the gravel reaches no farther than the weald clay. the same section shows one of the minor east and west anticlinal lines before alluded to (p. .). [illustration: fig. . section from the north escarpment of the south downs to barcombe. . gravel composed of partially rounded chalk flints. . chalk with and without flints. . lowest chalk or chalk marl (upper greensand wanting). . gault. . lower greensand. . weald clay.] _at what period the weald valley was denuded._--if we inquire at what geological period the denudation of the weald was effected, we shall immediately perceive that the question is limited to this point, whether it took place during or subsequent to the deposition of the eocene strata of the south of england. for in the basins of london and hampshire the eocene strata are conformable to the chalk, being horizontal where the beds of chalk are horizontal, and vertical where they are vertical, so that both series of rocks appear to have participated in nearly the same movements. at the eastern extremity of the isle of wight, some beds even of the freshwater series have been thrown on their edges, like those of the london clay. nevertheless we can by no means infer that all the tertiary deposits of the london and hampshire basins once extended like the chalk over the entire valley of the weald, because the denudation of the chalk and greensand may have been going on in the centre of that area, while contiguous parts of the sea were sufficiently deep to receive and retain the matter derived from that waste. thus while the waves and currents were excavating the longitudinal valleys d and c (fig. .), the deposits _a_ may have been thrown down to the bottom of the contiguous deep water e, the sediment being drifted through transverse fissures, as before explained. in this case, the rise of the formations nos. , , , , , may have been going on contemporaneously with the excavation of the valleys c and d, and with the accumulation of the tertiary strata _a_. [illustration: fig. . cross section.] this idea receives some countenance from the fact of the tertiary strata, near their junction with the chalk of the london and hampshire basins, often consisting of dense beds of sand and shingle, as at blackheath and in the addington hills near croydon. they also contain occasionally freshwater shells and the remains of land animals and plants, which indicate the former presence of land at no great distance, some part of which may have occupied the centre of the weald. such masses of well-rolled pebbles occurring in the lowest eocene strata, or those called "the plastic clay and sands" before described (no. . _b_, tab. p. .), imply the neighbourhood of an ancient shore. they also indicate the destruction of pre-existing chalk with flints. at the same time fossil shells of the genera _melania_, _cyclas_, and _unio_, appearing here and there in beds of the same age, together with plants and the bones of land animals, bear testimony to contiguous land, which probably constituted islands scattered over the space now occupied by the tertiary basins of the seine and thames. the stage of denudation represented in fig. ., p. ., may explain the state of things prevailing at points where such islands existed. by the alternate rising and sinking of the white chalk and older beds, a large area may have become overspread with gravelly sandy, and clayey beds of fluvio-marine and shallow-water origin, before any of the london clay proper (or calcaire grossier in france) were superimposed. this may account for the fact that patches of "plastic clay and sand" (no. . _b_, tab. p. .), are scattered over the surface of the chalk, reaching in some places to great heights, and approaching even the edges of the escarpments. we must suppose that subsequently a gradual subsidence took place in certain areas, which allowed the london clay proper to accumulate over the lower eocene sands and clays, in a deep sea. during this sinking down (the vertical amount of which equalled , and in parts of the isle of wight, according to mr. prestwich, feet), the work of denudation would be unceasing, being always however confined to those areas where land or islands existed. at length, when the bagshot sand had been in its turn thrown down on the london clay, the space covered by these two formations was again upraised from the sea to about the height which it has since retained. during this upheaval, the waves would again exert their power, not only on the white chalk and lower cretaceous and wealden strata, but also on the eocene formations of the london basin, excavating valleys and undermining cliffs as the strata emerged from the deep. there are grounds, as before stated (p. .), for presuming that the tertiary area of london was converted into land before that of hampshire, and for this reason it contains no marine eocene deposits so modern as those of barton cliff, or the still newer freshwater and fluvio-marine beds of hordwell and the isle of wight. these last seem unequivocally to demonstrate the local inequality of the upheaving and depressing movements of the period alluded to; for we find, in spite of the evidence afforded in alum and white cliff bays, of continued depression to the extent of or feet, that at the close of the eocene period a dense formation of freshwater strata was produced. the fossils of these strata bear testimony to rivers draining adjacent lands, and the existence of numerous quadrupeds on those lands. instead of such phenomena, the signs of an open sea might naturally have been expected as the consequence of so much subsidence, had not the depression been accompanied or followed by upheaval in a region immediately adjoining. when we attempt to speculate on the geographical changes which took place in the earlier part of the eocene epoch, and to restore in imagination the former state of the physical geography of the south-east of england, we shall do well to bear in mind that wherever there are proofs of great denudation, there also the greatest area of land has probably existed. in the same space, moreover, the oscillations of level, and the alternate submergence and emergence of coasts, may be presumed to have been most frequent; for these fluctuations facilitate the wasting and removing power of waves, currents, and rivers. we should also remember that there is always a tendency in the last denuding operations, to efface all signs of preceding denudation, or at least all those marks of waste from which alone a geologist can ascertain the date of the removal of the missing strata within the denuded area. it may often be difficult to settle the chronology even of the last of a series of such acts of removal, but it must be, in the nature of things, almost always impossible to assign a date to each of the antecedent denudations. if we wish to determine the times of the destruction of rocks, we must look any where rather than to the spaces once occupied by the missing rocks. we must inquire to what regions the ruins of the white chalk, greensand, wealden, and other strata which have disappeared were transported. we are then led at once to the examination of all the deposits newer than the chalk, and first to the oldest of these, the lower eocene, and its sand, shingle, and clay. in them, so largely developed in the immediate neighbourhood of the denuded area, we discover the wreck we are in search of, regularly stratified, and inclosing, in some of its layers, organic remains of a littoral, and sometimes fluviatile character. what more can we desire? the shores must have consisted of chalk, greensand, and wealden, since these were the only superficial rocks in the south-east of england, at the commencement of the eocene epoch. the waves of the sea, therefore, and the rivers were grinding down chalk-flints and chert from the greensand into shingle and sand, or were washing away calcareous and argillaceous matter from the cretaceous and wealden beds, during the whole of the eocene period. thus we obtain the date of a great part at least of that enormous amount of denudation of which we have such striking monuments in the space intervening between the north and south downs. [illustration: fig. . cross section. a. chalk with layers of flint dipping slightly to the south. _b._ ancient beach, consisting of fine sand, from one to four feet thick, covered by shingle from five to eight feet thick of pebbles of chalk-flint, granite, and other rocks, with broken shells of recent marine species, and bones of cetacea. _c._ elephant bed, about fifty feet thick, consisting of layers of white chalk rubble, with broken chalk-flints, in which deposit are found bones of ox, deer, horse, and mammoth. _d._ sand and shingle of modern beach.] there have been some movements of land on a smaller scale since the eocene period in the south-east of england. one of the latest of these happened in the pleistocene, or even perhaps as late as the post-pliocene period. the formation called by dr. mantell the elephant bed, at the foot of the chalk cliffs at brighton, is not merely a talus of calcareous rubble collected at the base of an inland cliff, but exhibits every appearance of having been spread out in successive horizontal layers by water in motion. the deposit alluded to skirts the shores between brighton and rottingdean, and another mass apparently of the same age occurs at dover. the phenomena appear to me to suggest the following conclusions:--first, the south-eastern part of england had acquired its actual configuration when the ancient chalk cliff a _a_ was formed, the beach of sand and shingle _b_ having then been thrown up at the base of the cliff. afterwards the whole coast, or at least that part of it where the elephant bed now extends, subsided to the depth of or feet; and during the period of submergence successive layers of white calcareous rubble _c_ were accumulated, so as to cover the ancient beach _b_. subsequently, the coast was again raised, so that the ancient shore was elevated to a level somewhat higher than its original position.[ -a] footnotes: [ -a] an account of these cliffs was read by the author to the british assoc. at glasgow, sept. . [ -b] seine-inferieure, p. . and pl. . fig. . [ -a] botley hill, near godstone, in surrey, was found by trigonometrical measurement to be feet above the level of the sea; and wrotham hill, near maidstone, which appears to be next in height of the north downs, feet. [ -b] my friend dr. mantell has kindly drawn up this scale at my request. [ -a] fitton, geol. of hastings, p. . [ -b] conybeare, outlines of geol., p. . [ -a] ibid., p. . [ -b] geol. of western sussex, p. . [ -a] see illustrations of this theory by dr. fitton, geol. sketch of hastings. [ -a] sir e. murchison, geol. sketch of sussex, &c., geol. trans., second series, vol. ii. p. . [ -b] see fig. . p. . [ -a] geol. soc. proceed. no. . p. . , and g. s. trans. ser. v. . [ -b] for farther information, see mantell's geol. of s. e. of england, p. . [ -a] soulèvemens jurassiques. paris, . [ -a] see above, p. . [ -a] see mantell's geol. of s. e. of england, p. . after re-examining the elephant bed in , i was no longer in doubt of its having been a regular subaqueous deposit. in , dr. mantell discovered in the shingle below the chalk-rubble the jawbone of a whale feet long, which must have belonged to an individual from to feet in length, medals of creation, p. . chapter xx. oolite and lias. subdivisions of the oolitic or jurassic group--physical geography of the oolite in england and france--upper oolite--portland stone and fossils--lithographic stone of solenhofen--middle oolite, coral rag--zoophytes--nerinæan limestone--diceras limestone--oxford clay, ammonites and belemnites--lower oolite, crinoideans--great oolite and bradford clay--stonesfield slate--fossil mammalia, placental and marsupial--resemblance to an australian fauna--doctrine of progressive development--collyweston slates--yorkshire oolitic coal-field--brora coal--inferior oolite and fossils. _oolitic or jurassic group._--below the freshwater group called the wealden, or, where this is wanting, immediately beneath the cretaceous formation, a great series of marine strata, commonly called "the oolite," occurs in england and many other parts of europe. this group has been so named, because, in the countries where it was first examined, the limestones belonging to it had an oolitic structure (see p. .). these rocks occupy in england a zone which is nearly miles in average breadth, and extends across the island, from yorkshire in the north-east, to dorsetshire in the south-west. their mineral characters are not uniform throughout this region; but the following are the names of the principal subdivisions observed in the central and south-eastern parts of england:-- oolite. upper { _a._ portland stone and sand. { _b._ kimmeridge clay. middle { _c._ coral rag. { _d._ oxford clay. lower { _e._ cornbrash and forest marble. { _f._ great oolite and stonesfield slate. { _g._ fuller's earth. { _h._ inferior oolite. the lias then succeeds to the inferior oolite. the upper oolitic system of the above table has usually the kimmeridge clay for its base; the middle oolitic system, the oxford clay. the lower system reposes on the lias, an argillo-calcareous formation, which some include in the lower oolite, but which will be treated of separately in the next chapter. many of these subdivisions are distinguished by peculiar organic remains; and though varying in thickness, may be traced in certain directions for great distances, especially if we compare the part of england to which the above-mentioned type refers with the north-east of france, and the jura mountains adjoining. in that country, distant above geographical miles, the analogy to the english type, notwithstanding the thinness, or occasional absence of the clays, is more perfect than in yorkshire or normandy. _physical geography._--the alternation, on a grand scale, of distinct formations of clay and limestone, has caused the oolitic and liassic series to give rise to some marked features in the physical outline of parts of england and france. wide valleys can usually be traced throughout the long bounds of country where the argillaceous strata crop out; and between these valleys the limestones are observed, composing ranges of hills, or more elevated grounds. these ranges terminate abruptly on the side on which the several clays rise up from beneath the calcareous strata. [illustration: fig. . cross section.] the annexed diagram will give the reader an idea of the configuration of the surface now alluded to, such as may be seen in passing from london to cheltenham, or in other parallel lines, from east to west, in the southern part of england. it has been necessary, however, in this drawing, greatly to exaggerate the inclination of the beds, and the height of the several formations, as compared to their horizontal extent. it will be remarked, that the lines of cliff, or escarpment, face towards the west in the great calcareous eminences formed by the chalk and the upper, middle, and lower oolites; and at the base of which we have respectively the gault, kimmeridge clay, oxford clay, and lias. this last forms, generally, a broad vale at the foot of the escarpment of inferior oolite, but where it acquires considerable thickness, and contains solid beds of marlstone, it occupies the lower part of the escarpment. the external outline of the country which the geologist observes in travelling eastward from paris to metz is precisely analogous, and is caused by a similar succession of rocks intervening between the tertiary strata and the lias; with this difference, however, that the escarpments of chalk, upper, middle, and lower oolites, face towards the east instead of the west. the chalk crops out from beneath the tertiary sands and clays of the paris basin, near epernay, and the gault from beneath the chalk and upper greensand at clermont-en-argonne; and passing from this place by verdun and etain to metz, we find two limestone ranges, with intervening vales of clay, precisely resembling those of southern and central england, until we reach the great plain of lias at the base of the inferior oolite at metz. it is evident, therefore, that the denuding causes have acted similarly over an area several hundred miles in diameter, sweeping away the softer clays more extensively than the limestones, and undermining these last so as to cause them to form steep cliffs wherever the harder calcareous rock was based upon a more yielding and destructible clay. this denudation probably occurred while the land was slowly rising out of the sea.[ -a] _upper oolite._ the portland stone has already been mentioned as forming in dorsetshire the foundation on which the freshwater limestone of the lower purbeck reposes (see p. .). it supplies the well-known building stone of which st. paul's and so many of the principal edifices of london are constructed. this upper member, characterized by peculiar marine fossils, rests on a dense bed of sand, called the portland sand, below which is the kimmeridge clay. in england these upper oolite formations are almost wholly confined to the southern counties. corals are rare in them, although one species is found plentifully at tisbury, in wiltshire, in the portland sand converted into flint and chert, the original calcareous matter being replaced by silex (fig. .). [illustration: fig. . _columnaria oblonga_, blainv. as seen on a polished slab of chert from the sand of the upper oolite, tisbury.] among the characteristic fossils of the upper oolite, may be mentioned the _ostrea deltoidea_ (fig. .), found in the kimmeridge clay throughout england and the north of france, and also in scotland, near brora. the _gryphæa virgula_ (fig. .), also met with in the same clay near oxford, is so abundant in the upper oolite of parts of france as to have caused the deposit to be termed "marnes à gryphées virgules." near clermont, in argonne, a few leagues from st. menehould, where these indurated marls crop out from beneath the gault, i have seen them, on decomposing, leave the surface of every ploughed field literally strewed over with this fossil oyster. [ illustrations: upper oolite: kimmeridge clay. / nat. size. fig. . _gryphæa virgula._ fig. . _ostrea deltoidea._] [illustration: fig. . _trigonia gibbosa._ / nat. size. _a._ the hinge. portland oolite, tisbury.] the kimmeridge clay consists, in great part, of a bituminous shale, sometimes forming an impure coal several hundred feet in thickness. in some places in wiltshire it much resembles peat; and the bituminous matter may have been, in part at least, derived from the decomposition of vegetables. but as impressions of plants are rare in these shales, which contain ammonites, oysters, and other marine shells, the bitumen may perhaps be of animal origin. the celebrated lithographic stone of solenhofen, in bavaria, belongs to one of the upper divisions of the oolite, and affords a remarkable example of the variety of fossils which may be preserved under favourable circumstances, and what delicate impressions of the tender parts of certain animals and plants may be retained where the sediment is of extreme fineness. although the number of testacea in this slate is small, and the plants few, and those all marine, count munster had determined no less than species of fossils when i saw his collection in ; and among them no less than seven _species_ of flying lizards, or pterodactyls, six saurians, three tortoises, sixty species of fish, forty-six of crustacea, and twenty-six of insects. these insects, among which is a libellula, or dragon-fly, must have been blown out to sea, probably from the same land to which the flying lizards, and other contemporaneous reptiles, resorted. _middle oolite._ _coral rag._--one of the limestones of the middle oolite has been called the "coral rag," because it consists, in part, of continuous beds of petrified corals, for the most part retaining the position in which they grew at the bottom of the sea. they belong chiefly to the genera _caryophyllia_ (fig. .), _agaricia_, and _astrea_, and sometimes form masses of coral feet thick. in the annexed figure of an _astrea_, from this formation, it will be seen that the cup-shaped cavities are deepest on the right-hand side, and that they grow more and more shallow, till those on the left side are nearly filled up. the last-named stars are supposed to be polyparia of advanced age. these coralline strata extend through the calcareous hills of the n.w. of berkshire, and north of wilts, and again recur in yorkshire, near scarborough. [illustration: fig. . _caryophyllia annularis_, parkin. coral rag, steeple ashton.] [illustration: fig . _astrea._ coral rag.] one of the limestones of the jura, referred to the age of the english coral rag, has been called "nerinæan limestone" (calcaire à nérinées) by m. thirria; _nerinæa_ being an extinct genus of univalve shells, much resembling the _cerithium_ in external form. the annexed section (fig. .) shows the curious form of the hollow part of each whorl, and also the perforation which passes up the middle of the columella. _n. goodhallii_ (fig. .) is another english species of the same genus, from a formation which seems to form a passage from the kimmeridge clay to the coral rag.[ -a] [illustration: fig. . _nerinæa hieroglyphica._ coral rag.] [illustration: fig. . _nerinæa goodhallii_, fitton. coral rag, weymouth. / nat. size.] a division of the oolite in the alps, regarded by most geologists as coeval with the english coral rag, has been often named "calcaire à dicerates," or "diceras limestone," from its containing abundantly a bivalve shell (see fig. .) of a genus allied to the _chama_. [illustration: fig. . cast of _diceras arietina_. coral rag, france.] [illustration: fig. . _cidaris coronata._ coral rag.] _oxford clay._--the coralline limestone, or "coral rag," above described, and the accompanying sandy beds, called "calcareous grits" of the middle oolite, rests on a thick bed of clay, called the oxford clay, sometimes not less than feet thick. in this there are no corals, but great abundance of cephalopoda of the genera ammonite and belemnite. (see fig. .) in some of the clay of very fine texture ammonites are very perfect, although somewhat compressed, and are seen to be furnished on each side of the aperture with a single horn-like projection (see fig. .). these were discovered in the cuttings of the great western railway, near chippenham, in , and have been described by mr. pratt.[ -a] [illustration: fig. . _belemnites hastatus._ oxford clay.] [illustration: fig. . _ammonites jason_, reinecke. syn. _a. elizabethæ_, pratt. oxford clay, christian malford, wiltshire.] [illustration: fig. . _belemnites puzosianus_, d'orb. oxford clay, christian malford. _a, a._ projecting processes of the shell or phragmocone. _b, c._ broken exterior of a conical shell called the phragmocone, which is chambered within, or composed of a series of shallow concave cells pierced by a siphuncle. _c, d._ the guard or osselet, which is commonly called the belemnite.] similar elongated processes have been also observed to extend from the shells of some belemnites discovered by dr. mantell in the same clay (see fig. .), who, by the aid of this and other specimens, has been able to throw much light on the structure of this singular extinct form of cuttle-fish.[ -a] _lower oolite._ the upper division of this series, which is more extensive than the preceding or middle oolite, is called in england the cornbrash. it consists of clays and calcareous sandstones, which pass downwards into the forest marble, an argillaceous limestone, abounding in marine fossils. in some places, as at bradford, this limestone is replaced by a mass of clay. the sandstones of the forest marble of wiltshire are often ripple-marked and filled with fragments of broken shells and pieces of drift-wood, having evidently been formed on a coast. rippled slabs of fissile oolite are used for roofing, and have been traced over a broad band of country from bradford, in wilts, to tetbury, in gloucestershire. these calcareous tile-stones are separated from each other by thin seams of clay, which have been deposited upon them, and have taken their form, preserving the undulating ridges and furrows of the sand in such complete integrity, that the impressions of small footsteps, apparently of crabs, which walked over the soft wet sands, are still visible. in the same stone the claws of crabs, fragments of echini, and other signs of a neighbouring beach are observed.[ -b] _great oolite._--although the name of coral-rag has been appropriated, as we have seen, to a member of the upper oolite before described, some portions of the lower oolite are equally intitled in many places to be called coralline limestones. thus the great oolite near bath contains various corals, among which the _eunomia radiata_ (fig. .) is very conspicuous, single individuals forming masses several feet in diameter; and having probably required, like the large existing brain-coral (_meandrina_) of the tropics, many centuries before their growth was completed. [illustration: fig. . _eunomia radiata_, lamouroux. _a._ section transverse to the tubes. _b._ vertical section, showing the radiation of the tubes. _c._ portion of interior of tubes magnified, showing striated surface.] [illustration: fig. . _apiocrinites rotundus_, or pear encrinite; miller. fossil at bradford, wilts. _a._ stem of _apiocrinites_, and one of the articulations, natural size. _b._ section at bradford of great oolite and overlying clay, containing the fossil encrinites. see text. _c._ three perfect individuals of apiocrinites, represented as they grew on the surface of the great oolite. _d._ body of the _apiocrinites rotundus_.] different species of _crinoideans_, or stone-lilies, are also common in the same rocks with corals; and, like them, must have enjoyed a firm bottom, where their root, or base of attachment, remained undisturbed for years (_c_, fig. .). such fossils, therefore, are almost confined to the limestones; but an exception occurs at bradford, near bath, where they are enveloped in clay. in this case, however, it appears that the solid upper surface of the "great oolite" had supported, for a time, a thick submarine forest of these beautiful zoophytes, until the clear and still water was invaded by a current charged with mud, which threw down the stone-lilies, and broke most of their stems short off near the point of attachment. the stumps still remain in their original position; but the numerous articulations once composing the stem, arms, and body of the zoophyte, were scattered at random through the argillaceous deposit in which some now lie prostrate. these appearances are represented in the section _b_, fig. ., where the darker strata represent the bradford clay, which some geologists class with the forest marble, others with the great oolite. the upper surface of the calcareous stone below is completely incrusted over with a continuous pavement, formed by the stony roots or attachments of the crinoidea; and besides this evidence of the length of time they had lived on the spot, we find great numbers of single joints, or circular plates of the stem and body of the encrinite, covered over with _serpulæ_. now these _serpulæ_ could only have begun to grow after the death of some of the stone-lilies, parts of whose skeletons had been strewed over the floor of the ocean before the irruption of argillaceous mud. in some instances we find that, after the parasitic _serpulæ_ were full grown, they had become incrusted over with a coral, called _berenicea diluviana_; and many generations of these polyps had succeeded each other in the pure water before they became fossil. [illustration: fig. . _a._ single plate or articulation of an encrinite overgrown with _serpulæ_ and corals. natural size bradford clay. _b._ portion of the same magnified, showing the coral _berenicea_ _diluviana_ covering one of the _serpulæ_.] we may, therefore, perceive distinctly that, as the pines and cycadeous plants of the ancient "dirt bed," or fossil forest, of the lower purbeck were killed by submergence under fresh water, and soon buried beneath muddy sediment, so an invasion of argillaceous matter put a sudden stop to the growth of the bradford encrinites, and led to their preservation in marine strata.[ -a] such differences in the fossils as distinguish the calcareous and argillaceous deposits from each other, would be described by naturalists as arising out of a difference in the _stations_ of species; but besides these, there are variations in the fossils of the higher, middle, and lower part of the oolitic series, which must be ascribed to that great law of change in organic life by which distinct assemblages of species have been adapted, at successive geological periods, to the varying conditions of the habitable surface. in a single district it is difficult to decide how far the limitation of species to certain minor formations has been due to the local influence of _stations_, or how far it has been caused by time or the creative and destroying law above alluded to. but we recognize the reality of the last-mentioned influence, when we contrast the whole oolitic series of england with that of parts of the jura, alps, and other distant regions, where there is scarcely any lithological resemblance; and yet some of the same fossils remain peculiar in each country to the upper, middle, and lower oolite formations respectively. mr. thurmann has shown how remarkably this fact holds true in the bernese jura, although the argillaceous divisions, so conspicuous in england, are feebly represented there, and some entirely wanting. [illustration: fig. . _terebratula digona._ bradford clay. nat. size.] the bradford clay above alluded to is sometimes feet thick, but, in many places, it is wanting; and, in others, where there are no limestones, it cannot easily be separated from the clays of the overlying "forest marble" and underlying "fuller's earth." the calcareous portion of the great oolite consists of several shelly limestones, one of which, called the bath oolite, is much celebrated as a building stone. in parts of gloucestershire, especially near minchinhampton, the great oolite, says mr. lycett, "must have been deposited in a shallow sea, where strong currents prevailed, for there are frequent changes in the mineral character of the deposit, and some beds exhibit false stratification. in others, heaps of broken shells are mingled with pebbles of rocks foreign to the neighbourhood, and with fragments of abraded madrepores, dicotyledonous wood, and crabs' claws. the shelly strata, also, have occasionally suffered denudation, and the removed portions have been replaced by clay."[ -a] in such shallow-water beds cephalopoda are rare, and, instead of ammonites and belemnites, numerous genera of carnivorous trachelipods appear. out of one hundred and forty-two species of univalves obtained from the minchinhampton beds, mr. lycett found no less than forty-one to be carnivorous. they belong principally to the genera _buccinum_, _pleurotoma_, _rostellaria_, _murex_, and _fusus_, and exhibit a proportion of zoophagous species not very different from that which obtains in warm seas of the recent period. these conchological results are curious and unexpected, since it was imagined that we might look in vain for the carnivorous trachelipods in rocks of such high antiquity as the great oolite, and it was a received doctrine that they did not begin to appear in considerable numbers till the eocene period when those two great families of cephalopoda, the ammonites and belemnites, had become extinct. _stonesfield slate._--the slate of stonesfield has been shown by mr. lonsdale to lie at the base of the great oolite.[ -b] it is a slightly oolitic shelly limestone, forming large spheroidal masses imbedded in sand, only feet thick, but very rich in organic remains. it contains some pebbles of a rock very similar to itself, and which may be portions of the deposit, broken up on a shore at low water or during storms, and redeposited. the remains of belemnites, trigoniæ, and other marine shells, with fragments of wood, are common, and impressions of ferns, cycadeæ, and other plants. several insects, also, and, among the rest, the wing-covers of beetles, are perfectly preserved (see fig. .), some of them approaching nearly to the genus _buprestis_.[ -a] the remains, also, of many genera of reptiles, such as _plesiosaur_, _crocodile_, and _pterodactyl_, have been discovered in the same limestone. [illustration: fig. . elytron of _buprestis_? stonesfield.] [illustration: fig. . bone of a reptile, formerly supposed to be the ulna of a cetacean; from the great oolite of enstone, near woodstock.] but the remarkable fossils for which the stonesfield slate is most celebrated, are those referred to the mammiferous class. the student should be reminded that in all the rocks described in the preceding chapters as older than the eocene, no bones of any land quadruped, or of any cetacean, have been discovered. yet we have seen that terrestrial plants were not rare in the lower cretaceous formation, and that in the wealden there was evidence of freshwater sediment on a large scale, containing various plants, and even ancient vegetable soils with the roots and erect stumps of trees. we had also in the same wealden many land-reptiles and winged-insects, which renders the absence of terrestrial quadrupeds the more striking. the want, however, of any bones of whales, seals, dolphins, and other aquatic mammalia, whether in the chalk or in the upper or middle oolite, is certainly still more remarkable. formerly, indeed, a bone from the great oolite of enstone, near woodstock, in oxfordshire, was cited, on the authority of cuvier, as referable to this class. dr. buckland, who stated this in his bridgewater treatise[ -b], had the kindness to send me the supposed ulna of a whale, that mr. owen might examine into its claims to be considered as cetaceous. it is the opinion of that eminent comparative anatomist that it cannot have belonged to the cetacea, because the fore-arm in these marine mammalia is invariably much flatter, and devoid of all muscular depressions and ridges, one of which is so prominent in the middle of this bone, represented in the above cut (fig. .). in saurians, on the contrary, such ridges exist for the attachment of muscles; and to some animal of that class the bone is probably referable. [illustration: fig. . _amphitherium prevostii_. stonesfield slate. natural size. _a_. coronoid process. _b_. condyle. _c_. angle of jaw. _d_. double-fanged molars.] these observations are made to prepare the reader to appreciate more justly the interest felt by every geologist in the discovery in the stonesfield slate of no less than seven specimens of lower jaws of mammiferous quadrupeds, belonging to three different species and to two distinct genera, for which the names of _amphitherium_ and _phascolotherium_ have been adopted. when cuvier was first shown one of these fossils in , he pronounced it to belong to a small ferine mammal, with a jaw much resembling that of an opossum, but differing from all known ferine genera, in the great number of the molar teeth, of which it had at least ten in a row. since that period, a much more perfect specimen of the same fossil, obtained by dr. buckland (see fig. .), has been examined by mr. owen, who finds that the jaw contained on the whole twelve molar teeth, with the socket of a small canine, and three small incisors, which are _in situ_, altogether amounting to sixteen teeth on each side of the lower jaw. [illustration: fig. . _amphitherium broderipii_. natural size. stonesfield slate.] the only question which could be raised respecting the nature of these fossils was, whether they belonged to a mammifer, a reptile, or a fish. now on this head the osteologist observes that each of the seven half jaws is composed of but one single piece, and not of two or more separate bones, as in fishes and most reptiles, or of two bones, united by a suture, as in some few species belonging to those classes. the condyle, moreover (_b_, fig. .), or articular surface, by which the lower jaw unites with the upper, is convex in the stonesfield specimens, and not concave as in fishes and reptiles. the coronoid process (_a_, fig. .) is well developed, whereas it is wanting or very small, in the inferior classes of vertebrata. lastly, the molar teeth in the _amphitherium_ and _phascolotherium_ have complicated crowns, and two roots (see _d_, fig. .), instead of being simple and with single fangs.[ -a] [illustration: fig. . _tupaia tana._ right ramus of lower jaw, natural size. a recent insectivorous mammal from sumatra.] [ illustrations: part of lower jaw of _tupaia tana_; twice natural size. fig. . end view seen from behind, showing the very slight inflection of the angle at _c_. fig. . side view of same.] [ illustrations: part of lower jaw of _didelphis azaræ_; recent, brazil. natural size. fig. . end view seen from behind, showing the inflection of the angle of the jaw, _c. d._ fig. . side view of same.] the only question, therefore, which could fairly admit of controversy was limited to this point, whether the fossil mammalia found in the lower oolite of oxfordshire ought to be referred to the marsupial quadrupeds, or to the ordinary placental series. cuvier had long ago pointed out a peculiarity in the form of the angular process (_c_, figs. . and .) of the lower jaw, as a character of the genus _didelphys_; and mr. owen has since established its generality in the entire marsupial series. in all these pouched quadrupeds, this process is turned inwards, as at _c d_, fig. . in the brazilian opossum, whereas in the placental series, as at _c_, figs. . and . there is an almost entire absence of such inflection. the _tupaia tana_ of sumatra has been selected by my friend mr. waterhouse, for this illustration, because that small insectivorous quadruped bears a great resemblance to those of the stonesfield _amphitherium_. by clearing away the matrix from the specimen of _amphitherium prevostii_ above represented (fig. .), mr. owen ascertained that the angular process (_c_) bent inwards in a slighter degree than in any of the known marsupialia; in short, the inflection does not exceed that of the mole or hedgehog. this fact turns the scale in favour of its affinities to the placental insectivora. nevertheless, the _amphitherium_ offers some points of approximation in its osteology to the marsupials, especially to the _myrmecobius_, a small insectivorous quadruped of australia, which has nine molars on each side of the lower jaw, besides a canine and three incisors.[ -b] another species of _amphitherium_ has been found at stonesfield (fig. . p. .), which differs from the former (fig. .) principally in being larger. [illustration: fig. . _phascolotherium bucklandi_, owen. _a._ natural size. _b._ molar of same magnified.] the second mammiferous genus discovered in the same slates was named originally by mr. broderip _didelphys bucklandi_ (see fig. .), and has since been called _phascolotherium_ by owen. it manifests a much stronger likeness to the marsupials in the general form of the jaw, and in the extent and position of its inflected angle, while the agreement with the living genus _didelphys_ in the number of the premolar and molar teeth, is complete.[ -a] on reviewing, therefore, the whole of the osteological evidence, it will be seen that we have every reason to presume that the _amphitherium_ and _phascolotherium_ of stonesfield represent both the placental and marsupial classes of mammalia; and if so, they warn us in a most emphatic manner, not to found rash generalizations respecting the non-existence of certain classes of animals at particular periods of the past, on mere negative evidence. the singular accident of our having as yet found nothing but the lower jaws of seven individuals, and no other bones of their skeletons, is alone sufficient to demonstrate the fragmentary manner in which the memorials of an ancient terrestrial fauna are handed down to us. we can scarcely avoid suspecting that the two genera above described, may have borne a like insignificant proportion to the entire assemblage of warm-blooded quadrupeds which flourished in the islands of the oolitic sea. mr. owen has remarked that as the marsupial genera, to which the _phascolotherium_ is most nearly allied, are now confined to new south wales and van diemen's land, so also is it in the australian seas, that we find the _cestracion_, a cartilaginous fish which has a bony palate, allied to those called _acrodus_ and _psammodus_ (see figs. , . p. .), so common in the oolite and lias. in the same australian seas, also, near the shore, we find the living _trigonia_, a genus of mollusca so frequently met with in the stonesfield slate. so, also, the araucarian pines are now abundant, together with ferns, in australia and its islands, as they were in europe in the oolitic period. many botanists incline to the opinion, that the _thuja_, _pine_, _cycas_, _zamia_, in short, all the gymnogens, belong to a less highly developed type of flowering plants than do the exogens; but even if this be admitted, no naturalist can ascribe a low standard of organization to the oolitic flora, since we meet with endogens of the most perfect structure in oolitic rocks, both above and below the stonesfield slate, as, for example, the _podocarya_ of buckland, a fruit allied to the _pandanus_, found in the inferior oolite (see fig. .), and the _carpolithes conica_ of the coral rag. the doctrine, therefore, of a regular series of progressive development at successive eras in the animal and vegetable kingdoms, from beings of a more simple to those of a more complex organization, receives a check, if not a refutation, from the facts revealed to us by the study of the lower oolites. [illustration: fig. . portion of a fossil fruit of _podocarya_ magnified. (buckland's bridgew. treat. pl. .) inferior oolite, charmouth, dorset.] the stonesfield slate, in its range from oxfordshire to the north-east, is represented by flaggy and fissile sandstones, as at collyweston in northamptonshire, where, according to the researches of messrs. ibbetson and morris, it contains many shells, such as _trigonia angulata_, also found at stonesfield. but the northamptonshire strata of this age assume a more marine character, or appear at least to have been formed farther from land. they inclose, however, some fossil ferns, such as _pecopteris polypodioides_, of species common to the oolites of the yorkshire coast[ -a], where rocks of this age put on all the aspect of a true coal-field; thin seams of coal having actually been worked in them for more than a century. [illustration: fig. . _pterophyllum comptum._ (syn. _cycadites comptus_.) upper sandstone and shale, gristhorpe, near scarborough.] in the north-west of yorkshire, the formation alluded to consists of an upper and a lower carbonaceous shale, abounding in impressions of plants, divided by a limestone considered by many geologists as the representative of the great oolite; but the scarcity of marine fossils makes all comparisons with the subdivisions adopted in the south extremely difficult. a rich harvest of fossil ferns has been obtained from the upper carbonaceous shales and sandstones at gristhorpe, near scarborough (see figs. , .). the lower shales are well exposed in the sea-cliffs at whitby, and are chiefly characterized by ferns and cycadeæ. they contain, also, a species of calamite, and a fossil called _equisetum columnare_, which maintains an upright position in sandstone strata over a wide area. shells of the genus _cypris_ and _unio_, collected by mr. bean from these yorkshire coal-bearing beds, point to the estuary or fluviatile origin of the deposit. [illustration: fig. . _hemitelites brownii_, goepp. syn. _phlebopteris contigua_, lind. & hutt. upper carbonaceous strata, lower oolite, gristhorpe, yorkshire.] at brora, in sutherlandshire, a coal formation, probably coeval with the above, or belonging to some of the lower divisions of the oolitic period, has been mined extensively for a century or more. it affords the thickest stratum of pure vegetable matter hitherto detected in any secondary rock in england. one seam of coal of good quality has been worked - / feet thick, and there are several feet more of pyritous coal resting upon it. _inferior oolite._--between the great and inferior oolite, near bath, an argillaceous deposit called "the fuller's earth," occurs, but is wanting in the north of england. the inferior oolite is a calcareous freestone, usually of small thickness, which sometimes rests upon, or is replaced by, yellow sands, called the sands of the inferior oolite. these last, in their turn, repose upon the lias in the south and west of england. among the characteristic shells of the inferior oolite, i may instance _terebratula spinosa_ (fig. .), and _pholadomya fidicula_ (fig. .). the extinct genus _pleurotomaria_ is also a form very common in this division as well as in the oolitic system generally. it resembles the _trochus_ in form, but is marked by a singular cleft (_a_, fig. .) on the right side of the mouth. [illustration: fig. . _terebratula spinosa._ inferior oolite.] [illustration: fig. . _a._ _pholadomya fidicula_, / nat. size. inf. ool. _b._ heart-shaped anterior termination of the same.] [illustration: fig. . _pleurotomaria ornata._ ferruginous oolite, normandy. inferior oolite, england.] as illustrations of shells having a great vertical range, i may allude to _trigonia clavellata_, found in the upper and inferior oolite, and _t. costata_, common to the upper, middle, and lower oolite; also _ostrea marshii_ (fig. .), common to the cornbrash of wilts and the inferior oolite of yorkshire; and _ammonites striatulus_ (fig. .) common to the inferior oolite and lias. [illustration: fig. . _ostrea marshii._ / nat. size. middle and lower oolite.] [illustration: fig. . _ammonites striatulus_, sow. / nat. size. inferior oolite and lias.] such facts by no means invalidate the general rule, that certain fossils are good chronological tests of geological periods; but they serve to caution us against attaching too much importance to single species, some of which may have a wider, others a more confined vertical range. we have before seen that, in the successive tertiary formations, there are species common to older and newer groups, yet these groups are distinguishable from one another by a comparison of the whole assemblage of fossil shells proper to each. footnotes: [ -a] see chapters vi. and xix. [ -a] fitton, geol. trans., second series, vol. iv. pl. . fig. . [ -a] s. p. pratt, annals of nat. hist., november, . [ -a] see phil. trans. , p. . [ -b] p. scrope, geol. proceed., march, . [ -a] for a fuller account of these encrinites, see buckland's bridgewater treatise, vol. i. p. . [ -a] lycett, quart. geol. journ. vol. iv. p. . [ -b] proceedings geol. soc. vol. i. p. . [ -a] see buckland's bridgewater treatise; and brodie's fossil insects, where it is suggested that these elytra may belong to _priomus_. [ -b] vol. i. p. . [ -a] i have given a figure in the principles of geology, chap. ix., of another stonesfield specimen of _amphitherium prevostii_, in which the sockets and roots of the teeth are finely exposed. [ -b] a figure of this recent _myrmecobius_ will be found in the principles, chap. ix. [ -a] owen's british fossil mammals, p. . [ -a] ibbetson and morris, report of brit. ass., , p. . chapter xxi. oolite and lias--_continued_. mineral character of lias--name of gryphite limestone--fossil shells and fish--ichthyodorulites--reptiles of the lias--ichthyosaur and plesiosaur--marine reptile of the galapagos islands--sudden destruction and burial of fossil animals in lias--fluvio-marine beds in gloucestershire and insect limestone--origin of the oolite and lias, and of alternating calcareous and argillaceous formations--oolitic coal-field of virginia, in the united states. _lias._--the english provincial name of lias has been very generally adopted for a formation of argillaceous limestone, marl, and clay, which forms the base of the oolite, and is classed by many geologists as part of that group. they pass, indeed, into each other in some places, as near bath, a sandy marl called the marlstone of the lias being interposed, and partaking of the mineral characters of the upper lias and inferior oolite. these last-mentioned divisions have also some fossils in common, such as the _avicula inæquivalvis_ (fig. .). nevertheless the lias may be traced throughout a great part of europe as a separate and independent group, of considerable thickness, varying from to feet, containing many peculiar fossils, and having a very uniform lithological aspect. although usually conformable to the oolite, it is sometimes, as in the jura, unconformable. in the environs of lons-le-saulnier, for instance, in the department of jura, the strata of lias are inclined at an angle of about °, while the incumbent oolitic marls are horizontal. [illustration: fig. . _avicula inæquivalvis_, sow.] the peculiar aspect which is most characteristic of the lias in england, france, and germany, is an alternation of thin beds of blue or grey limestone with a surface becoming light-brown when weathered, these beds being separated by dark-coloured narrow argillaceous partings, so that the quarries of this rock, at a distance, assume a striped and riband-like appearance.[ -a] although the prevailing colour of the limestone of this formation is blue, yet some beds of the lower lias are of a yellowish white colour, and have been called white lias. in some parts of france, near the vosges mountains, and in luxembourg, m. e. de beaumont has shown that the lias containing _gryphæa arcuata_, _plagiostoma giganteum_ (see fig. .), and other characteristic fossils, becomes arenaceous; and around the hartz, in westphalia and bavaria, the inferior parts of the lias are sandy, and sometimes afford a building stone. [illustration: fig. . _plagiostoma giganteum._ lias.] [illustration: fig. . _gryphæa incurva_, sow. (_g. arcuata_, lam.)] [illustration: fig. . _nautilus truncatus._ lias.] the name of gryphite limestone has sometimes been applied to the lias, in consequence of the great number of shells which it contains of a species of oyster, or _gryphæa_ (fig. ., see also fig. . p. .). many cephalopoda, also, such as _ammonite_, _belemnite_, and _nautilus_ (fig. .), prove the marine origin of the formation. [illustration: fig. . scales of _lepidotus gigas_, agas. _a._ two of the scales detached.] the fossil fish resemble generically those of the oolite, belonging all, according to m. agassiz, to extinct genera, and differing remarkably from the ichthyolites of the cretaceous period. among them is a species of _lepidotus_ (_l. gigas_, agas.) (fig. .), which is found in the lias of england, france, and germany.[ -a] this genus was before mentioned (p. .) as occurring in the wealden, and is supposed to have frequented both rivers and coasts. the teeth of a species of _acrodus_, also, are very abundant in the lias (fig. .). [illustration: fig. . _acrodus nobilis_, agas. (tooth); commonly called fossil leach. lias, lyme regis, and germany.] [illustration: fig. . _hybodus reticulatus_, agas. lias, lyme regis. _a._ part of fin, commonly called ichthyodorulite. _b._ tooth.] but the remains of fish which have excited more attention than any others, are those large bony spines called _ichthyodorulites_ (_a_, fig. .), which were once supposed by some naturalists to be jaws, and by others weapons, resembling those of the living _balistes_ and _silurus_; but which m. agassiz has shown to be neither the one nor the other. the spines, in the genera last mentioned, articulate with the backbone, whereas there are no signs of any such articulation in the ichthyodorulites. these last appear to have been bony spines which formed the anterior part of the dorsal fin, like that of the living genera _cestracion_ and _chimæra_ (see _a_, fig. .). in both of these genera, the posterior concave face is armed with small spines like that of the fossil _hybodus_ (fig. .), one of the shark family found fossil at lyme regis. such spines are simply imbedded in the flesh, and attached to strong muscles. "they serve," says dr. buckland, "as in the _chimæra_ (fig. .), to raise and depress the fin, their action resembling that of a moveable mast, raising and lowering backwards the sail of a barge."[ -a] [illustration: fig. . _chimæra monstrosa._[ -b] _a._ spine forming anterior part of the dorsal fin.] _reptiles of the lias._--it is not, however, the fossil fish which form the most striking feature in the organic remains of the lias; but the reptiles, which are extraordinary for their number, size, and structure. among the most singular of these are several species of _ichthyosaurus_ and _plesiosaurus_. the genus _ichthyosaurus_, or fish-lizard, is not confined to this formation, but has been found in strata as high as the chalk-marl and gault of england, and as low as the muschelkalk of germany, a formation which immediately succeeds the lias in the descending order.[ -c] it is evident from their fish-like vertebræ, their paddles, resembling those of a porpoise or whale, the length of their tail, and other parts of their structure, that the habits of the ichthyosaurs were aquatic. their jaws and teeth show that they were carnivorous; and the half-digested remains of fishes and reptiles, found within their skeletons, indicate the precise nature of their food.[ -d] a specimen of the hinder fin or paddle of _ichthyosaurus communis_ was discovered in at barrow-on-soar, by sir p. egerton, which distinctly exhibits on its posterior margin the remains of cartilaginous rays that bifurcate as they approach the edge, like those in the fin of a fish (see _a_, fig. .). it had previously been supposed, says mr. owen, that the locomotive organs of the ichthyosaurus were enveloped, while living, in a smooth integument, like that of the turtle and porpoise, which has no other support than is afforded by the bones and ligaments within; but it now appears that the fin was much larger, expanding far beyond its osseous framework, and deviating widely in its fish-like rays from the ordinary reptilian type. in fig. . the posterior bones, or digital ossicles of the paddle, are seen near _b_; and beyond these is the dark carbonized integument of the terminal half of the fin, the outline of which is beautifully defined.[ -a] mr. owen believes that, besides the fore-paddles, these short-and stiff-necked saurians were furnished with a tail-fin without bones and purely tegumentary, expanding in a vertical direction; an organ of motion which enabled them to turn their heads rapidly.[ -b] [illustration: fig. . _ichthyosaurus communis_, restored by conybeare and cuvier. _a._ costal vertebræ.] [illustration: fig. . _plesiosaurus dolichodeirus_, restored by rev. w. d. conybeare. _a._ cervical vertebra.] [illustration: fig. . posterior part of hind fin or paddle of _ichthyosaurus communis_.] mr. conybeare was enabled, in , after examining many skeletons nearly perfect, to give an ideal restoration of the osteology of this genus, and of that of the _plesiosaurus_.[ -a] (see figs. , .) the latter animal had an extremely long neck and small head, with teeth like those of the crocodile, and paddles analogous to those of the _ichthyosaurus_, but larger. it is supposed to have lived in shallow seas and estuaries, and to have breathed air like the ichthyosaur, and our modern cetacea.[ -b] some of the reptiles above mentioned were of formidable dimensions. one specimen of _ichthyosaurus platyodon_, from the lias at lyme, now in the british museum, must have belonged to an animal more than feet in length; and another of the _plesiosaurus_, in the same collection, is feet long. the form of the _ichthyosaurus_ may have fitted it to cut through the waves like the porpoise; but it is supposed that the _plesiosaurus_, at least the long-necked species (fig. .), was better suited to fish in shallow creeks and bays defended from heavy breakers. in many specimens both of ichthyosaur and plesiosaur the bones of the head, neck, and tail, are in their natural position, while those of the rest of the skeleton are detached and in confusion. mr. stutchburg has suggested that their bodies after death became inflated with gases, and, while the abdominal viscera were decomposing, the bones, though disunited, were retained within the tough dermal covering as in a bag, until the whole, becoming water-logged, sank to the bottom.[ -c] as they belonged to individuals of all ages they are supposed, by dr. buckland, to have experienced a violent death; and the same conclusion might also be drawn from their having escaped the attacks of their own predaceous race, or of fishes, found fossil in the same beds. [illustration: fig . _amblyrhynchus cristatus_, bell. length varying from to feet. the only existing marine lizard now known. _a._ tooth, natural size and magnified.] for the last twenty years, anatomists have agreed that these extinct saurians must have inhabited the sea; and it was argued that, as there are now chelonians, like the tortoise, living in fresh water, and others, as the turtle, frequenting the ocean, so there may have been formerly some saurians proper to salt, others to fresh water. the common crocodile of the ganges is well known to frequent equally that river and the brackish and salt water near its mouth; and crocodiles are said in like manner to be abundant both in the rivers of the isla de pinos (or isle of pines), south of cuba, and in the open sea round the coast. more recently a saurian has been discovered of aquatic habits and exclusively marine. this creature was found in the galapagos islands, during the visit of h. m. s. beagle to that archipelago, in , and its habits were then observed by mr. darwin. the islands alluded to are situated under the equator, nearly miles to the westward of the coast of south america. they are volcanic, some of them being or feet high; and one of them, albemarle island, miles long. the climate is mild; very little rain falls; and, in the whole archipelago, there is only one rill of fresh water that reaches the coast. the soil is for the most part dry and harsh, and the vegetation scanty. the birds, reptiles, plants, and insects are, with very few exceptions, of species found no where else in the world, although all partake, in their general form, of a south american type. of the mammalia, says mr. darwin, one species alone appears to be indigenous, namely, a large and peculiar kind of mouse; but the number of lizards, tortoises, and snakes is so great, that it may be called a land of reptiles. the variety, indeed, of species is small; but the individuals of each are in wonderful abundance. there is a turtle, a large tortoise (_testudo indicus_), four lizards, and about the same number of snakes, but no frogs or toads. two of the lizards belong to the family _iguanidæ_ of bell, and to a peculiar genus (_amblyrhynchus_) established by that naturalist, and so named from their obtusely truncated head and short snout.[ -a] of these lizards one is terrestrial in its habits, and burrows in the ground, swarming everywhere on the land, having a round tail, and a mouth somewhat resembling in form that of the tortoise. the other is aquatic, and has its tail flattened laterally for swimming (see fig. .). "this marine saurian," says mr. darwin, "is extremely common on all the islands throughout the archipelago. it lives exclusively on the rocky sea-beaches, and i never saw one even ten yards inshore. the usual length is about a yard, but there are some even feet long. it is of a dirty black colour, sluggish in its movements on the land; but, when in the water, it swims with perfect ease and quickness by a serpentine movement of its body and flattened tail, the legs during this time being motionless, and closely collapsed on its sides. their limbs and strong claws are admirably adapted for crawling over the rugged and fissured masses of lava which everywhere form the coast. in such situations, a group of six or seven of these hideous reptiles may oftentimes be seen on the black rocks, a few feet above the surf, basking in the sun with outstretched legs. their stomachs, on being opened, were found to be largely distended with minced sea-weed, of a kind which grows at the bottom of the sea at some little distance from the coast. to obtain this, the lizards go out to sea in shoals. one of these animals was sunk in salt water, from the ship, with a heavy weight attached to it, and on being drawn up again after an hour it was quite active and unharmed. it is not yet known by the inhabitants where this animal lays its eggs; a singular fact, considering its abundance, and that the natives are well acquainted with the eggs of the terrestrial _amblyrhynchus_, which is also herbivorous."[ -a] in those deposits now forming by the sediment washed away from the wasting shores of the galapagos islands the remains of saurians, both of the land and sea, as well as of chelonians and fish, may be mingled with marine shells, without any bones of land quadrupeds or batrachian reptiles; yet even here we should expect the remains of marine mammalia to be imbedded in the new strata, for there are seals, besides several kinds of cetacea, on the galapagian shores; and, in this respect, the parallel between the modern fauna, above described, and the ancient one of the lias, would not hold good. _sudden destruction of saurians._--it has been remarked, and truly, that many of the fish and saurians, found fossil in the lias, must have met with sudden death and immediate burial; and that the destructive operation, whatever may have been its nature, was often repeated. "sometimes," says dr. buckland, "scarcely a single bone or scale has been removed from the place it occupied during life; which could not have happened had the uncovered bodies of these saurians been left, even for a few hours, exposed to putrefaction, and to the attacks of fishes, and other smaller animals at the bottom of the sea."[ -b] not only are the skeletons of the ichthyosaurs entire, but sometimes the contents of their stomachs still remain between their ribs, as before remarked, so that we can discover the particular species of fish on which they lived, and the form of their excrements. not unfrequently there are layers of these coprolites, at different depths in the lias, at a distance from any entire skeletons of the marine lizards from which they were derived; "as if," says sir h. de la beche, "the muddy bottom of the sea received small sudden accessions of matter from time to time, covering up the coprolites and other exuviæ which had accumulated during the intervals."[ -a] it is farther stated that, at lyme regis, those surfaces only of the coprolites which lay uppermost at the bottom of the sea have suffered partial decay, from the action of water before they were covered and protected by the muddy sediment that has afterwards permanently enveloped them.[ -b] numerous specimens of the pen-and-ink fish (_sepia loligo_, lin.; _loligo vulgaris_, lam.) have also been met with in the lias at lyme, with the ink-bags still distended, containing the ink in a dried state, chiefly composed of carbon, and but slightly impregnated with carbonate of lime. these cephalopoda, therefore, must, like the saurians, have been soon buried in sediment; for, if long exposed after death, the membrane containing the ink would have decayed.[ -c] as we know that river fish are sometimes stifled, even in their own element, by muddy water during floods, it cannot be doubted that the periodical discharge of large bodies of turbid fresh water into the sea may be still more fatal to marine tribes. in the principles of geology i have shown that large quantities of mud and drowned animals have been swept down into the sea by rivers during earthquakes, as in java, in ; and that undescribable multitudes of dead fishes have been seen floating on the sea after a discharge of noxious vapours during similar convulsions.[ -d] but, in the intervals between such catastrophes, strata may have accumulated slowly in the sea of the lias, some being formed chiefly of one description of shell, such as ammonites, others of gryphites. from the above remarks the reader will infer that the lias is for the most part a marine deposit. some members, however, of the series, especially in the lowest part of it, have an estuary character, and must have been formed within the influence of rivers. in gloucestershire, where there is a good type of the lias of the west of england, it may be divided into an upper mass of shale with a base of marlstone, and a lower series of shales with underlying limestones and shales. we learn from the researches of the rev. p. b. brodie[ -e], that in the superior of these two divisions numerous remains of insects and plants have been detected in several places, mingled with marine shells; but in the inferior division similar fossils are still more plentiful. one band, rarely exceeding a foot in thickness, has been named the "insect limestone." it passes upwards into a shale containing _cypris_ and _estheria_, and is charged with the wing-cases of several genera of coleoptera, and with some nearly entire beetles, of which the eyes are preserved. the nervures of the wings of neuropterous insects (fig. .) are beautifully perfect in this bed. ferns, with leaves of monocotyledonous plants, and freshwater shells, such as _cyclas_ and _unio_, accompany the insects in some places, while in others marine shells predominate, the fossils varying apparently as we examine the bed nearer or farther from the ancient land, or the source whence the fresh water was derived. there are two, or even three, bands of "insect limestone" in several sections, and they have been ascertained by mr. brodie to retain the same lithological and zoological characters when traced from the centre of warwickshire to the borders of the southern part of wales. after studying specimens of these insects from the lias, mr. westwood declares that they comprise both wood-eating and herb-devouring beetles of the linnean genera _elater_, _carabus_, &c., besides grasshoppers (_gryllus_), and detached wings of dragon-flies and may-flies, or insects referable to the linnean genera _libellula_, _ephemera_, _hemerobius_, and _panorpa_, in all belonging to no less than twenty-four families. the size of the species is usually small, and such as taken alone would imply a temperate climate; but many of the associated organic remains of other classes must lead to a different conclusion. [illustration: fig. . wing of a neuropterous insect, from the lower lias, gloucestershire. (rev. b. brodie.)] _fossil plants._--among the vegetable remains of the lias, several species of _zamia_ have been found at lyme regis, and the remains of coniferous plants at whitby. fragments of wood are common, and often converted into limestone. that some of this wood, though now petrified, was soft when it first lay at the bottom of the sea, is shown by a specimen now in the museum of the geological society (see fig. .), which has the form of an _ammonite_ indented on its surface. [illustration: fig. . petrified wood.] m. ad. brongniart enumerates forty-seven liassic acrogens, most of them ferns; and fifty gymnogens, of which thirty-nine are cycads, and eleven conifers. among the cycads the predominance of _zamites_ and _nilsonia_, and among the ferns the numerous genera with leaves having reticulated veins (as in fig. . p. .), are mentioned as botanical characteristics of this era.[ -a] _origin of the oolite and lias._--if we now endeavour to restore, in imagination, the ancient condition of the european area at the period of the oolite and lias, we must conceive a sea in which the growth of coral reefs and shelly limestones, after proceeding without interruption for ages, was liable to be stopped suddenly by the deposition of clayey sediment. then, again, the argillaceous matter, devoid of corals, was deposited for ages, and attained a thickness of hundreds of feet, until another period arrived when the same space was again occupied by calcareous sand, or solid rocks of shell and coral, to be again succeeded by the recurrence of another period of argillaceous deposition. mr. conybeare has remarked of the entire group of oolite and lias, that it consists of repeated alternations of clay, sandstone, and limestone, following each other in the same order. thus the clays of the lias are followed by the sands of the inferior oolite, and these again by shelly and coralline limestone (bath oolite, &c.); so, in the middle oolite, the oxford clay is followed by calcareous grit and "coral rag;" lastly, in the upper oolite, the kimmeridge clay is followed by the portland sand and limestone.[ -a] the clay beds, however, as sir h. de la beche remarks, can be followed over larger areas than the sands or sandstones.[ -b] it should also be remembered that while the oolitic system becomes arenaceous, and resembles a coal-field in yorkshire, it assumes, in the alps, an almost purely calcareous form, the sands and clays being omitted; and even in the intervening tracts, it is more complicated and variable than appears in ordinary descriptions. nevertheless, some of the clays and intervening limestones do, in reality, retain a pretty uniform character, for distances of from to miles from east to west and north to south. according to m. thirria, the entire oolitic group in the department of the haute-saône, in france, may be equal in thickness to that of england; but the importance of the argillaceous divisions is in the inverse ratio to that which they exhibit in england, where they are about equal to twice the thickness of the limestones, whereas, in the part of france alluded to, they reach only about a third of that thickness.[ -c] in the jura the clays are still thinner; and in the alps they thin out and almost vanish. in order to account for such a succession of events, we may imagine, first, the bed of the ocean to be the receptacle for ages of fine argillaceous sediment, brought by oceanic currents, which may have communicated with rivers, or with part of the sea near a wasting coast. this mud ceases, at length, to be conveyed to the same region, either because the land which had previously suffered denudation is depressed and submerged, or because the current is deflected in another direction by the altered shape of the bed of the ocean and neighbouring dry land. by such changes the water becomes once more clear and fit for the growth of stony zoophytes. calcareous sand is then formed from comminuted shell and coral, or, in some cases, arenaceous matter replaces the clay; because it commonly happens that the finer sediment, being first drifted farthest from coasts, is subsequently overspread by coarse sand, after the sea has grown shallower, or when the land, increasing in extent, whether by upheaval or by sediment filling up parts of the sea, has approached nearer to the spots first occupied by fine mud. in order to account for another great formation, like the oxford clay, again covering one of coral limestone, we must suppose a sinking down like that which is now taking place in some existing regions of coral between australia and south america. the occurrence of subsidences, on so vast a scale, may have caused the bed of the ocean and the adjoining land, throughout great parts of the european area, to assume a shape favourable to the deposition of another set of clayey strata; and this change may have been succeeded by a series of events analogous to that already explained, and these again by a third series in similar order. both the ascending and descending movements may have been extremely slow, like those now going on in the pacific; and the growth of every stratum of coral, a few feet of thickness, may have required centuries for its completion, during which certain species of organic beings disappeared from the earth, and others were introduced in their place; so that, in each set of strata, from the upper oolite to the lias, some peculiar and characteristic fossils were embedded. _oolite and lias of the united states._ [illustration: fig. . section showing the geological position of the james river, or east virginian coal-field. a. granite, gneiss, &c. b. coal-measures. c. tertiary strata. d. drift or _ancient alluvium_.] there are large tracts on the globe, as in russia and the united states, where all the members of the oolitic series are unrepresented. in the state of virginia, however, at the distance of about miles eastward of richmond, the capital of that state, there is a regular coal-field occurring in a depression of the granite rocks (see section, fig. .), which professor w. b. rogers first correctly referred to the age of the lower part of the jurassic group. this opinion i was enabled to confirm after collecting a large number of fossil plants, fish, and shells, and examining the coal-field throughout its whole area. it extends miles from north to south, and from to , from east to west. the plants consist chiefly of zamites, calamites, and equisetums, and these last are very commonly met with in a vertical position more or less compressed perpendicularly. it is clear that they grew in the places where they now lie buried in strata of hardened sand and mud. i found them maintaining their erect attitude, at points many miles distant from others, in beds both above and between the seams of coal. in order to explain this fact we must suppose such shales and sandstones to have been gradually accumulated during the slow and repeated subsidence of the whole region. it is worthy of remark that the _equisetum columnare_ of these virginian rocks appears to be undistinguishable from the species found in the oolitic sandstones near whitby in yorkshire, where it also is met with in an upright position. one of the american ferns, _pecopteris whitbyensis_, is also a species common to the yorkshire oolites.[ -a] these virginian coal-measures are composed of grits, sandstones, and shales, exactly resembling those of older or primary date in america and europe, and they rival or even surpass the latter in the richness and thickness of the seams. one of these, the main seam, is in some places from to feet thick, composed of pure bituminous coal. on descending a shaft feet deep, in the blackheath mines in chesterfield county, i found myself in a chamber more than feet high, caused by the removal of this coal. timber props of great strength supported the roof, but they were seen to bend under the incumbent weight. the coal is like the finest kinds shipped at newcastle, and when analysed yields the same proportions of carbon and hydrogen, a fact worthy of notice when we consider that this fuel has been derived from an assemblage of plants very distinct specifically, and in part generically, from those which have contributed to the formation of the ancient or paleozoic coal. the fossil fish of these richmond strata belong to the liassic genus _tetragonolepis_, and to a new genus which i have called _dictyopyge_. shells are very rare, as usually in all coal-bearing deposits, but a species of _posidonomya_ is in such profusion in some shaley beds as to divide them like the plates of mica in micaceous shales (see fig. .). [illustration: fig. . oolitic coal-shale, richmond, virginia. _a._ _posidonomya._ _b._ young of same.] in india, especially in cutch, a formation occurs clearly referable to the oolitic and liassic type, as shown by the shells, corals, and plants; and there also coal has been procured from one member of the group. footnotes: [ -a] conyb. and phil. p. . [ -a] agassiz, pois. fos. vol. ii. tab. , . [ -a] bridgewater treatise, p. . [ -b] agassiz, poissons fossiles, vol. iii. tab. c. fig. . [ -c] ibid. p. . [ -d] ibid. p. . [ -a] geol. soc. proceedings, vol. iii. p. . . [ -b] geol. trans. second series, vol. v. p. . [ -a] geol. trans., second series, vol. i. pl. . [ -b] conybeare and de la beche. geol. trans.; and buckland, bridgew. treat., p. . [ -c] quart. geol. journ. vol. ii. p. . [ -a] +amblys+, _amblys_, blunt; and +rhygchos+, _rhynchus_, snout. [ -a] darwin's journal, chap. xix. [ -b] bridgew. treat., p. . [ -a] geological researches, p. . [ -b] buckland, bridgew. treat., p. . [ -c] ibid. [ -d] see principles, _index_, lancerote, graham island, calabria. [ -e] a history of fossil insects, &c. . london. [ -a] tableau des veg. fos. , p. . [ -a] con. and phil., p. . [ -b] geol. researches, p. . [ -c] burat's d'aubuisson, tom. ii. p. . [ -a] see description of the coal-field by the author, and the plants by c. j. f. bunbury, esq., quart. geol. journ., vol. iii. p. . chapter xxii. trias or new red sandstone group. distinction between new and old red sandstone--between upper and lower new red--the trias and its three divisions--most largely developed in germany--keuper and its fossils--muschelkalk--fossil plants of bunter--triassic group in england--bone-bed of axmouth and aust--red sandstone of warwickshire and cheshire--footsteps of _chirotherium_ in england and germany--osteology of the _labyrinthodon_--identification of this batrachian with the chirotherium--origin of red sandstone and rock-salt--hypothesis of saline volcanic exhalations--theory of the precipitation of salt from inland lakes or lagoons--saltness of the red sea--new red sandstone in the united states--fossil footprints of birds and reptiles in the valley of the connecticut--antiquity of the red sandstone containing them. between the lias and the coal, or carboniferous group, there is interposed, in the midland and western counties of england, a great series of red loams, shales, and sandstones, to which the name of the new red sandstone formation was first given, to distinguish it from other shales and sandstones called the "old red" (_c_, fig. .), often identical in mineral character, which lie immediately beneath the coal (_b_). [illustration: fig. . cross section. _a._ new red sandstone. _b._ coal. _c._ old red.] the name of "red marl" has been incorrectly applied to the red clays of this formation, as before explained (p. .), for they are remarkably free from calcareous matter. the absence, indeed, of carbonate of lime, as well as the scarcity of organic remains, together with the bright red colour of most of the rocks of this group, causes a strong contrast between it and the jurassic formations before described. before the distinctness of the fossil remains characterizing the upper and lower part of the english new red had been clearly recognized, it was found convenient to have a common name for all the strata intermediate in position between the lias and coal; and the term "poikilitic" was proposed by messrs. conybeare and buckland[ -a], from +poikilos+, poikilos, _variegated_, some of the most characteristic strata of this group having been called _variegated_ by werner, from their exhibiting spots and streaks of light-blue, green, and buff colour, in a red base. a single term, thus comprehending both upper and lower new red, or the triassic and permian groups of modern classifications, may still be useful in describing districts where we have to speak of masses of red sandstone and shale, referable, in part, to both these eras, but which, in the absence of fossils, it is impossible to divide. _trias or upper new red sandstone group._ the accompanying table will explain the subdivisions generally adopted for the uppermost of the two systems above alluded to, and the names given to them in england and on the continent. synonyms. german. french. { _a._ saliferous and } } { gypseous shales and } keuper } marnes irisées. trias or upper { sandstone } } new red { sandstone { _b._ (wanting in england) } muschelkalk { muschelkalk, ou { { calcaire { { coquillier. { { _c._ sandstone and } bunter- } grès bigarré. { quartzose conglomerate } sandstein } i shall first describe this group as it occurs in south western and north western germany, for it is far more fully developed there than in england or france. it has been called the trias by german writers, or the triple group, because it is separable into three distinct formations, called the "keuper," the "muschelkalk," and the "bunter-sandstein." [illustration: fig. . _equisetites columnaris._ (syn. _equisetum columnare_.) fragment of stem, and small portion of same magnified. keuper.] _the keuper_, the first or newest of these, is feet thick in würtemberg, and is divided by alberti into sandstone, gypsum, and carbonaceous slate-clay.[ -a] remains of reptiles, called _nothosaurus_ and _phytosaurus_, have been found in it with _labyrinthodon_; the detached teeth, also, of placoid fish and of rays, and of the genera _saurichthys_ and _gyrolepis_ (figs. , , p. .). the plants of the keuper are generically very analogous to those of the lias and oolite, consisting of ferns, equisetaceous plants, cycads, and conifers, with a few doubtful monocotyledons. a few species, such as _equisetites columnaris_, are common to this group, and the oolite. _the muschelkalk_ consists chiefly of a compact, greyish limestone, but includes beds of dolomite in many places, together with gypsum and rock-salt. this limestone, a rock wholly unrepresented in england, abounds in fossil shells, as the name implies. among the cephalopoda there are no belemnites, and no ammonites with foliated sutures, as in the incumbent lias and oolite, but a genus allied to the ammonite, called _ceratite_ by de haan, in which the descending lobes (see _a_, _b_, _c_, fig. .) terminate in a few small denticulations pointing inwards. among the bivalve shells, the _posidonia minuta_, goldf. (_posidonomya minuta_, bronn) (see fig. .), is abundant, ranging through the keuper, muschelkalk, and bunter-sandstein; and _avicula socialis_, fig. ., having a similar range, is very characteristic of the muschelkalk in germany, france, and poland. [illustration: fig. . _ceratites nodosus._ muschelkalk. _a._ side view. _b._ front view. _c._ partially denticulated outline of the septa dividing the chambers.] [illustration: fig. . _posidonia minuta_, goldf. (_posidonomya minuta_, bronn.)] [illustration: fig. . avicula. characteristic of the muschelkalk. _a._ _avicula socialis._ _b._ side view of same.] the abundance of the heads and stems of lily encrinites, _encrinus liliiformis_ (or _encrinites moniliformis_), show the slow manner in which some beds of this limestone have been formed in clear sea-water. [illustration: fig. . voltzia. bunter-sandstein. _a._ _voltzia heterophylla._ (syn. _voltzia brevifolia_.) _b._ portion of same magnified to show fructification. sulzbad.] _the bunter-sandstein_ consists of various coloured sandstones, dolomites, and red-clays, with some beds, especially in the hartz, of calcareous pisolite or roe-stone, the whole sometimes attaining a thickness of more than feet. the sandstone of the vosges, according to von meyer, is proved, by the presence of _labyrinthodon_, to belong to this lowest member of the triassic group. at sulzbad (or soultz-les-bains), near strasburg, on the flanks of the vosges, many plants have been obtained from the "bunter," especially conifers of the extinct genus _voltzia_, peculiar to this period, in which even the fructification has been preserved. (see fig. .) out of thirty species of ferns, cycads, conifers, and other plants, enumerated by m. ad. brongniart, in , as coming from the "grès bigarré," or bunter, not one is common to the keuper.[ -a] the footprints of a reptile (_labyrinthodon_) have been observed on the clays of this member of the trias, near hildburghausen, in saxony, impressed on the upper surface of the beds, and standing out as casts in relief from the under sides of incumbent slabs of sandstone. to these i shall again allude in the sequel; they attest, as well as the accompanying ripple-marks, and the cracks which traverse the clays, the gradual formation in shallow water, and sometimes between high and low water, of the beds of this formation. _triassic group in england._ in england the lias is succeeded by conformable strata of red and green marl, or clay. there intervenes, however, both in the neighbourhood of axmouth, in devonshire, and in the cliffs of westbury and aust, in gloucestershire, on the banks of the severn, a dark-coloured stratum, well known by the name of the "bone-bed." it abounds in the remains of saurians and fish, and was formerly classed as the lowest bed of the lias; but sir p. egerton has shown that it should be referred to the upper new red sandstone, for it contains an assemblage of fossil fish which are either peculiar to this stratum, or belong to species well known in the muschelkalk of germany. these fish belong to the genera _acrodus_, _hybodus_, _gyrolepis_, and _saurichthys_. among those common to the english bone-bed and the muschelkalk of germany are _hybodus plicatilis_ (fig. .), _saurichthys apicalis_ (fig. .), _gyrolepis tenuistriatus_ (fig. .), and _g. albertii_. remains of saurians have also been found in the bone-bed, and plates of an _encrinus_. [illustration: fig. . _hybodus plicatilis._ teeth. bone-bed, aust and axmouth.] [illustration: fig. . _saurichthys apicalis._ tooth; nat. size, and magnified. axmouth.] [illustration: fig. . _gyrolepis tenuistriatus._ scale; nat. size, and magnified. axmouth.] the strata of red and green marl, which follow the bone-bed in the descending order at axmouth and aust, are destitute of organic remains; as is the case, for the most part, in the corresponding beds in almost every part of england. but fossils have lately been found at a few localities in sandstones of this formation, in worcestershire and warwickshire, and among them the bivalve shell called _posidonia minuta_, goldf., before mentioned (fig. . p. .). the upper member of the english "new red" containing this shell, in those parts of england, is, according to messrs. murchison and strickland, feet thick, and consists chiefly of red marl or slate, with a band of sandstone. spines of _hybodus_, called _ichthyodorulites_, teeth of fishes, and footprints of reptiles, with remains of a saurian called _rhyncosaurus_, were observed by the same geologists in these strata.[ -a] in cheshire and lancashire the gypseous and saliferous red shales and loams of the trias are between and feet thick. in some places lenticular masses of rock-salt are interpolated between the argillaceous beds, the origin of which will be spoken of in the sequel. [illustration: fig. . single footstep of _chirotherium_. bunter sandstein, saxony; one eighth of nat. size.] [illustration: fig. . line of footsteps on slab of sandstone. hildburghausen, in saxony.] the lower division or english representative of the "bunter" attains a thickness of feet in the counties last mentioned. besides red and green shales and red sandstones, it comprises much soft white quartzose sandstone, in which the trunks of silicified trees have been met with at allesley hill, near coventry. several of them were a foot and a half in diameter, and some yards in length, decidedly of coniferous wood, and showing rings of annual growth.[ -b] impressions, also, of the footsteps of animals have been detected in lancashire and cheshire in this formation. some of the most remarkable occur a few miles from liverpool, in the whitish quartzose sandstone of storton hill, on the west side of the mersey. they bear a close resemblance to tracks first observed in a member of the upper new red sandstone, at the village of hesseberg, near hildburghausen, in saxony, to which i have already alluded. for many years these footprints have been referred to a large unknown quadruped, provisionally named _chirotherium_ by professor kaup, because the marks both of the fore and hind feet resembled impressions made by a human hand. (see fig. .) the footmarks at hesseberg are partly concave and partly in relief; the former, or the depressions, are seen upon the upper surface of the sandstone slabs, but those in relief are only upon the lower surfaces, being in fact natural casts, formed in the subjacent footprints as in moulds. the larger impressions, which seem to be those of the hind foot, are generally inches in length, and in width, and one was inches long. near each large footstep, and at a regular distance (about an inch and a half), before it, a smaller print of a fore foot, inches long and inches wide, occurs. the footsteps follow each other in pairs, each pair in the same line, at intervals of inches from pair to pair. the large as well as the small steps show the great toes alternately on the right and left side; each step makes the print of five toes, the first or great toe being bent inwards like a thumb. though the fore and hind foot differ so much in size, they are nearly similar in form. the similar footmarks afterwards observed in a rock of corresponding age at storton hill, were imprinted on five thin beds of clay, superimposed one upon the other in the same quarry, and separated by beds of sandstone. on the lower surface of the sandstone strata, the solid casts of each impression are salient, in high relief, and afford models of the feet, toes, and claws of the animals which trod on the clay. as neither in germany nor in england any bones or teeth had been met with in the same identical strata as the footsteps, anatomists indulged, for several years, in various conjectures respecting the mysterious animals from which they might have been derived. professor kaup suggested that the unknown quadruped might have been allied to the _marsupialia_; for in the kangaroo the first toe of the fore foot is in a similar manner set obliquely to the others, like a thumb, and the disproportion between the fore and hind feet is also very great. but m. link conceived that some of the four species of animals of which the tracks had been found in saxony might have been gigantic _batrachians_; and dr. buckland designated some of the footsteps as those of a small web-footed animal, probably crocodilean. in the course of these discussions several naturalists of liverpool, in their report on the storton quarries, declared their opinion that each of the thin seams of clay in which the sandstone casts were moulded had formed successively a surface above water, over which the _chirotherium_ and other animals walked, leaving impressions of their footsteps, and that each layer had been afterwards submerged by a sinking down of the surface, so that a new beach was formed at low water above the former, on which other tracks were then made. the repeated occurrence of ripple-marks at various heights and depths in the red sandstone of cheshire had been explained in the same manner. it was also remarked that impressions of such depth and clearness could only have been made by animals walking on the land, as their weight would have been insufficient to make them sink so deeply in yielding clay under water. they must therefore have been air-breathers. when the inquiry had been brought to this point, the reptilian remains discovered in the trias, both of germany and england, were carefully examined by mr. owen. he found, after a microscopic investigation of the teeth from the german sandstone called keuper, and from the sandstone of warwick and leamington, that neither of them could be referred to true saurians, although they had been named _mastodonsaurus_ and _phytosaurus_ by jäger (fig. .). it appeared that they were of the _batrachian_ order, and attested the former existence of frogs of gigantic dimensions in comparison with any now living. both the continental and english fossil teeth exhibited a most complicated texture, differing from that previously observed in any reptile, whether recent or extinct, but most nearly analogous to the _ichthyosaurus_. a section of one of these teeth exhibits a series of irregular folds, resembling the labyrinthic windings of the surface of the brain; and from this character mr. owen has proposed the name _labyrinthodon_ for the new genus. by his permission, the annexed representation (fig. .) of part of one is given from his "odontography," plate . a. the entire length of this tooth is supposed to have been about three inches and a half, and the breadth at the base one inch and a half. [illustration: fig. . tooth of _labyrinthodon_; nat. size. warwick sandstone.] [illustration: fig. . transverse section of tooth of _labyrinthodon jaegeri_, owen (_mastodonsaurus jaegeri_, meyer); nat. size, and a segment magnified. _a._ pulp cavity, from which the processes of pulp and dentine radiate.] when mr. owen had satisfied himself, from an inspection of the cranium, jaws, and teeth, that a gigantic _batrachian_ had existed at the period of the trias or upper new red sandstone, he soon found, from the examination of various bones derived from the same formation, that he could define three species of _labyrinthodon_, and that in this genus the hind extremities were much larger than the anterior ones. this circumstance, coupled with the fact of the _labyrinthodon_ having existed at the period when the _chirotherian_ footsteps were made, was the first step towards the identification of those tracks with the newly discovered _batrachian_. it was at the same time observed that the footmarks of _chirotherium_ were more like those of toads than of any other living animal; and, lastly, that the size of the three species of _labyrinthodon_ corresponded with the size of three different kinds of footprints which had already been supposed to belong to three distinct _chirotheria_. it was moreover inferred, with confidence, that the _labyrinthodon_ was an _air-breathing_ reptile from the structure of the nasal cavity, in which the posterior outlets were at the back part of the mouth, instead of being directly under the anterior or external nostrils. it must have respired air after the manner of saurians, and may therefore have imprinted on the shore those footsteps, which, as we have seen, could not have originated from an animal walking under water. it is true that the structure of the foot is still wanting, and that a more connected and complete skeleton is required for demonstration; but the circumstantial evidence above stated is strong enough to produce the conviction that the _chirotherium_ and _labyrinthodon_ are one and the same. in order to show the manner in which one of these formidable _batrachians_ may have impressed the mark of its feet upon the shore, mr. owen has attempted a restoration, of which a reduced copy is annexed. [illustration: fig. . _labyrinthodon pachygnathus_, owen.] the only bones of this species at present known are those of the head, the pelvis, and part of the scapula, which are shown by stronger lines in the above figure. there is reason for believing that the head was not smooth externally, but protected by bony scutella. _origin of red sandstone and rock salt._ we have seen that, in various parts of the world, red and mottled clays, and sandstones, of several distinct geological epochs, are found associated with salt, gypsum, magnesian limestone, or with one or all of these substances. there is, therefore, in all likelihood, a general cause for such a coincidence. nevertheless, we must not forget that there are dense masses of red and variegated sandstones and clays, thousands of feet in thickness, and of vast horizontal extent, wholly devoid of saliferous or gypseous matter. there are also deposits of gypsum and of muriate of soda, as in the blue clay formation of sicily, without any accompanying red sandstone or red clay. to account for deposits of red mud and red sand, we have simply to suppose the disintegration of ordinary crystalline or metamorphic schists. thus, in the eastern grampians of scotland, as, for example, in the north of forfarshire, the mountains of gneiss, mica-schist, and clay-slate, are overspread with alluvium, derived from the disintegration of those rocks; and the mass of detritus is stained by oxide of iron, of precisely the same colour as the old red sandstone of the adjoining lowlands. now this alluvium merely requires to be swept down to the sea, or into a lake, to form strata of red sandstone and red marl, precisely like the mass of the "old red" or new red systems of england, or those tertiary deposits of auvergne (see p. .), before described, which are in lithological characters quite undistinguishable. the pebbles of gneiss in the eocene red sandstone of auvergne point clearly to the rocks from which it has been derived. the red colouring matter may, as in the grampians, have been furnished by the decomposition of hornblende, or mica, which contain oxide of iron in large quantity. it is a general fact, and one not yet accounted for, that scarcely any fossil remains are preserved in stratified rocks in which this oxide of iron abounds; and when we find fossils in the new or old red sandstone in england, it is in the grey, and usually calcareous beds, that they occur. the gypsum and saline matter, occasionally interstratified with such red clays and sandstones of various ages, primary, secondary, and tertiary, have been thought by some geologists to be of volcanic origin. submarine and subaerial exhalations often occur in regions of earthquakes and volcanos far from points of actual eruption, and charged with sulphur, sulphuric salts, and with common salt or muriate of soda. in a word, they are vents by which all the products which issue in a state of sublimation from the craters of active volcanos, obtain a passage from the interior of the earth to the surface. that such gaseous emanations and mineral springs, impregnated with the ingredients before enumerated, and often intensely heated, continue to flow out unaltered in composition and temperature for ages, is well known. but before we can decide on their real instrumentality in producing in the course of ages beds of gypsum, salt, and dolomite, we require to know what are the chemical changes actually in progress in seas where this volcanic agency is at work. yet the origin of rock-salt is a problem of so much interest in theoretical geology as to demand a full discussion of another hypothesis advanced on the subject; namely, that which attributes the precipitation of the salt to evaporation, whether of inland lakes or of lagoons communicating with the ocean. at northwich, in cheshire, two beds of salt, in great part unmixed with earthy matter, attain the extraordinary thickness of and even feet. the upper surface of the highest bed is very uneven, forming cones and irregular figures. between the two masses there intervenes a bed of indurated clay, traversed with veins of salt. the highest bed thins off towards the south-west, losing feet in thickness in the course of a mile.[ -a] the horizontal extent of these particular masses in cheshire and lancashire is not exactly known; but the area, containing saliferous clays and sandstones, is supposed to exceed miles in diameter, while the total thickness of the trias in the same region is estimated by mr. ormerod at more than feet. ripple-marked sandstones, and the footprints of animals, before described, are observed at so many levels that we may safely assume the whole area to have undergone a slow and gradual depression during the formation of the red sandstone. the evidence of such a movement, wholly independent of the presence of salt itself, is very important in reference to the theory under consideration. in the "principles of geology" (chap. .), i published a map, furnished to me by the late sir alexander burnes, of that singular flat region called the runn of cutch, near the delta of the indus, which is square miles in area, or equal in extent to about one-fourth of ireland. it is neither land nor sea, but is dry during a part of every year, and again covered by salt water during the monsoons. some parts of it are liable, after long intervals, to be overflowed by river-water. its surface supports no grass, but is encrusted over, here and there, by a layer of salt, about an inch in depth, caused by the evaporation of sea-water. certain tracts have been converted into dry land by upheaval during earthquakes since the commencement of the present century, and, in other directions, the boundaries of the runn have been enlarged by subsidence. that successive layers of salt might be thrown down, one upon the other, over thousands of square miles, in such a region, is undeniable. the supply of brine from the ocean would be as inexhaustible as the supply of heat from the sun to cause evaporation. the only assumption required to enable us to explain a great thickness of salt in such as area is, the continuance, for an indefinite period, of a subsiding movement, the country preserving all the time a general approach to horizontality. pure salt could only be formed in the central parts of basins, where no sand could be drifted by the wind, or sediment be brought by currents. should the sinking of the ground be accelerated, so as to let in the sea freely, and deepen the water, a temporary suspension of the precipitation of salt would be the only result. on the other hand, if the area should dry up, ripple-marked sands and the footprints of animals might be formed, where salt had previously accumulated. according to this view the thickness of the salt, as well as of the accompanying beds of mud and sand, becomes a mere question of time, or requires simply a repetition of similar operations. mr. hugh miller, in an able discussion of this question, refers to dr. frederick parrot's account, in his journey to ararat ( ), of the salt lakes of asia. in several of these lakes west of the river manech, "the water, during the hottest season of the year, is covered on its surface with a crust of salt nearly an inch thick, which is collected with shovels into boats. the crystallization of the salt is effected by rapid evaporation from the sun's heat and the supersaturation of the water with muriate of soda; the lake being so shallow that the little boats trail on the bottom and leave a furrow behind them, so that the lake must be regarded as a wide pan of enormous superficial extent, in which the brine can easily reach the degree of concentration required." another traveller, major harris, in his "highlands of ethiopia," describes a salt lake, called the bahr assal, near the abyssinian frontier, which once formed the prolongation of the gulf of tadjara, but was afterwards cut off from the gulf by a broad bar of lava or of land upraised by an earthquake. "fed by no rivers, and exposed in a burning climate to the unmitigated rays of the sun, it has shrunk into an elliptical basin, seven miles in its transverse axis, half filled with smooth water of the deepest cærulian hue, and half with a solid sheet of glittering snow-white salt, the offspring of evaporation." "if," says mr. hugh miller, "we suppose, instead of a barrier of lava, that sand-bars were raised by the surf on a flat arenaceous coast during a slow and equable sinking of the surface, the waters of the outer gulf might occasionally topple over the bar, and supply fresh brine when the first stock had been exhausted by evaporation.[ -a] we may add that the permanent impregnation of the waters of a large shallow basin with salt, beyond the proportion which is usual in the ocean, would cause it to be uninhabitable by mollusca or fish, as is the case in the dead sea, and the muriate of soda might remain in excess, even though it were occasionally replenished by irruptions of the sea. should the saline deposit be eventually submerged, it might, as we have seen from the example of the runn of cutch, be covered by a freshwater formation containing fluviatile organic remains; and in this way the apparent anomaly of beds of sea-salt and clays devoid of marine fossils, alternating with others of freshwater origin, may be explained. dr. g. buist, in a recent communication to the bombay geographical society (vol. ix.), has asked how it happens that the red sea should not exceed the open ocean in saltness, by more than / th per cent. the red sea receives no supply of water from any quarter save through the straits of babelmandeb; and there is not a single river or rivulet flowing into it from a circuit of miles of shore. the countries around are all excessively sterile and arid, and composed, for the most part, of burning deserts. from the ascertained evaporation in the sea itself, dr. buist computes that nearly feet of pure water must be carried off from the whole of its surface annually, this being probably equivalent to / th part of its whole volume. the red sea, therefore, ought to have per cent. added annually to its saline contents; and as these constitute per cent. by weight, or - / per cent. in volume of its entire mass, it ought, assuming the average depth to be feet, which is supposed to be far beyond the truth, to have been converted into one solid salt formation in less than years.[ -a] does the red sea receive a supply of water from the ocean, through the narrow straits of babelmandeb, sufficient to balance the loss by evaporation? and is there an undercurrent of heavier saline water annually flowing outwards? if not, in what manner is the excess of salt disposed of? an investigation of this subject by our nautical surveyors may perhaps aid the geologist in framing a true theory of the origin of rock-salt. _on the new red sandstone of the valley of the connecticut river in the united states._ in a depression of the granitic or hypogene rocks in the states of massachusetts and connecticut, strata of red sandstone, shale, and conglomerate are found occupying an area more than miles in length from north to south, and about to miles in breadth, the beds dipping to the eastward at angles varying from to degrees. the extreme inclination of degrees is rare, and only observed in the neighbourhood of masses of trap which have been intruded into the red sandstone while it was forming, or before the newer parts of the deposit had been completed. having examined this series of rocks in many places, i feel satisfied that they were formed in shallow water, and for the most part near the shore, and that some of the beds were from time to time raised above the level of the water, and laid dry, while a newer series, composed of similar sediment, was forming. the red flags of thin-bedded sandstone are often ripple-marked, and exhibit on their under sides casts of cracks formed in the underlying red and green shales. these last must have shrunk by drying before the sand was spread over them. on some shales of the finest texture impressions of rain drops may be seen, and casts of them in the incumbent argillaceous sandstones. having observed similar markings produced by showers, of which the precise date was known, on the recent red mud of the bay of fundy, and casts in relief of the same, on layers of dried mud thrown down by subsequent tides, i feel no doubt in regard to the origin of some of the ancient connecticut impressions. i have also seen on the mud-flats of the bay of fundy the footmarks of birds (_tringa minuta_), which daily run along the borders of that estuary at low water, and which i have described in my travels.[ -b] similar layers of red mud, now hardened and compressed into shale, are laid open on the banks of the connecticut, and retain faithfully the impressions and casts of the feet of numerous birds and reptiles which walked over them at the time when they were deposited, probably in the triassic period. according to professor hitchcock, the footprints of no less than thirty-two species of bipeds, and twelve of quadrupeds, have been already detected in these rocks. thirty of these are believed to be those of birds, four of lizards, two of chelonians, and six of batrachians. the tracks have been found in more than twenty places, scattered through an extent of nearly miles from north to south, and they are repeated through a succession of beds attaining at some points a thickness of more than feet, which may have been thousands of years in forming.[ -a] [illustration: fig. . footprints of a bird. turner's falls, valley of the connecticut. (see dr. deane, mem. of amer. acad. vol. iv. .)] as considerable scepticism is naturally entertained in regard to the nature of the evidence derived from footprints, it may be well to enumerate some facts respecting them on which the faith of the geologist may rest. when i visited the united states in , more than impressions had been observed by professor hitchcock, in the district alluded to, and all of them were indented on the upper surface of the layers, while the corresponding casts, standing out in relief, were always on the lower surfaces or planes of the strata. if we follow a single line of marks we find them uniform in size, and nearly uniform in distance from each other, the toes of two successive footprints, turning alternately right and left (see fig. .). such single lines indicate a biped; and there is generally such a deviation from a straight line, in any three successive prints, as we remark in the tracks left by birds. there is also a striking relation between the distance separating two footprints in one series and the size of the impressions; in other words, an obvious proportion between the length of the stride and the dimension of the creature which walked over the mud. if the marks are small, they may be half an inch asunder; if gigantic, as, for example, where the toes are inches long, they are occasionally feet and a half apart. the bipedal impressions are for the most part trifid, and show the same number of joints as exist in the feet of living tridactylous birds. now such birds have three phalangeal bones for the inner toe, four for the middle and five for the outer one (see fig. .); but the impression of the terminal joint is that of the nail only. the fossil footprints exhibit regularly, where the joints are seen, the same number; and we see in each continuous line of tracks the three-jointed and five-jointed toes placed alternately outwards, first on the one side and then on the other. it is not often that the matrix has been fine enough to retain impressions of the integument or skin of the foot; but in one fine specimen found at turner's falls on the connecticut, by dr. deane, these markings are well preserved, and have been recognized by mr. owen as resembling the skin of the ostrich, and not that of reptiles.[ -b] much care is required to ascertain the precise layer of a laminated rock on which an animal has walked, because the impression usually extends downwards through several laminæ; and if the upper layer originally trodden upon is wanting, one or more joints, or even in some cases an entire toe, which sank less deep into the soft ground, may disappear, and yet the remainder of the footprint be well defined. the size of several of the fossil impressions of the connecticut red sandstone so far exceeds that of any living ostrich, that naturalists at first were extremely adverse to the opinion of their having been made by birds, until the bones and almost entire skeleton of the _dinornis_ and of other feathered giants of new zealand were discovered. their dimensions have at least destroyed the force of this particular objection. the magnitude of the impressions of the feet of a heavy animal, which has walked on soft mud, increases for some distance below the surface originally trodden upon. in order, therefore, to guard against exaggeration, the casts rather than the mould are relied on. these casts show that some of the fossil birds had feet four times as large as the ostrich, but not perhaps larger than the _dinornis_. some of the quadrupedal footprints which accompany those of birds are analogous to european _chirotheria_, and with a similar disproportion between the hind and fore feet. others resemble that remarkable reptile, the _rhyncosaurus_ of the english trias, a creature having some relation in its osteology both to chelonians and birds. other imprints, again, are like those of turtles. among the supposed bipedal tracks, a single distinct example only has been observed of feet in which there are four toes directed forwards. in this case a series of four footprints is seen, each inches long and wide, with joints much resembling those in the toes of birds. professor agassiz has suggested that it might have belonged to a gigantic bipedal batrachian; but the evidence on this subject is too defective to warrant such a bold conjecture, and if we were to give the reins to our imagination, we might as well conceive a bird having four toes projecting forwards as a huge two-legged frog. nor should we forget that some quadrupeds place the hind foot so precisely on the spot just quitted by the fore foot, as to produce a single line of imprints like a biped. no bones have as yet been met with, whether of reptiles or birds, in the rocks of the connecticut, but there are numerous coprolites; and an ingenious argument has been derived by mr. dana, from the analysis of these bodies, and the proportion they contain of uric acid, phosphate of lime, carbonate of lime, and organic matter, to show that, like guano, they are the droppings of birds, rather than of reptiles.[ -a] mr. darwin, in his "journal of a voyage in the beagle," informs us that the "south american ostriches, although they live on vegetable matter, such as roots and grass, are repeatedly seen at bahia blanca (lat. ° s.), on the coast of buenos ayres, coming down at low water to the extensive mud-banks which are then dry, for the sake, as the gauchos say, of feeding on small fish." they readily take to the water, and have been seen at the bay of san blas, and at port valdez, in patagonia, swimming from island to island.[ -a] it is therefore evident, that in our times a south american mud-bank might be trodden simultaneously by ostriches, alligators, tortoises, and frogs; and the impressions left, in the nineteenth century, by the feet of these various tribes of animals, would not differ from each other more entirely than do those attributed to birds, saurians, chelonians, and batrachians, in the rocks of the connecticut. to determine the exact age of the red sandstone and shale containing these ancient footprints in the united states, is not possible at present. no fossil shells have yet been found in the deposit, nor plants in a determinable state. the fossil fish are numerous and very perfect; but they are of a peculiar type, which was originally referred to the genus _palæoniscus_, but has since, with propriety, been ascribed, by sir philip egerton, to a new genus. to this he has given the name of _ischypterus_, from the great size and strength of the fulcral rays of the dorsal fin (from +ischys+; strength, and +pteron+, a fin). they differ from _palæoniscus_, as mr. redfield first pointed out, by having the vertebral column prolonged to a more limited extent into the upper lobe of the tail, or, in the language of m. agassiz, they are less heterocercal. the teeth also, according to sir p. egerton, who, in , examined for me a fine series of specimens which i procured at durham, connecticut, differ from those of _palæoniscus_ in being strong and conical. that the sandstones containing these fish are of older date than the strata containing coal, before described (p. .) as occurring near richmond in virginia, is highly probable. these were shown to be as old at least as the oolite and lias. the higher antiquity of the connecticut beds cannot be proved by direct superposition, but may be presumed from the general structure of the country. that structure proves them to be newer than the movements to which the appalachian or alleghany chain owes its flexures, and this chain includes the ancient coal formation among its contorted rocks. the unconformable position of this _new red_ with ornithichnites on the edges of the inclined primary or paleozoic rocks of the appalachians is seen at . of the section, fig. . p. . the absence of fish with decidedly heterocercal tails may afford an argument against the permian age of the formation; and the opinion that the red sandstone is triassic, seems, on the whole, the best that we can embrace in the present state of our knowledge. footnotes: [ -a] buckland, bridgew. treat., vol. ii. p. . [ -a] monog. des bunten sandsteins. [ -a] tableau des genres de veg. fos., dict. univ. . [ -a] geol. trans., second series, vol. v. [ -b] buckland, proc. geol. soc. vol. ii. p. .; and murchison and strickland geol. trans., second ser., vol. v. p. . [ -a] ormerod, quart. geol. journ. , vol. iv. p. . [ -a] hugh miller, first impressions of england, , pp. . . [ -a] buist, trans. of bombay geograph. soc. , vol. ix. p. . [ -b] travels in north america, vol. ii. p. . [ -a] hitchcock, mem. of amer. acad. new ser., vol. iii. p. . [ -b] this specimen is now in dr. mantell's museum. [ -a] amer. journ. of sci. vol. xlviii. p. . [ -a] journal of voyage of beagle, &c. d edition, p. . . chapter xxiii. permian or magnesian limestone group. fossils of magnesian limestone and lower new red distinct from the triassic--term permian--english and german equivalents--marine shells and corals of english magnesian limestone--palæoniscus and other fish of the marl slate--thecodont saurians of dolomitic conglomerate of bristol--zechstein and rothliegendes of thuringia--permian flora--its generic affinity to the carboniferous--psaronites or tree-ferns. when the use of the term "poikilitic" was explained in the last chapter, i stated, that in some parts of england it is scarcely possible to separate the red marls and sandstones so called (originally named "the new red"), into two distinct geological systems. nevertheless, the progress of investigation, and a careful comparison of english rocks between the lias and the coal with those occupying a similar geological position in germany and russia, has enabled geologists to divide the poikilitic formation; and has even shown that the lowermost of the two divisions is more closely connected, by its fossil remains, with the carboniferous group than with the trias. if, therefore, we are to draw a line between the secondary and primary fossiliferous strata, as between the tertiary and secondary, it must run through the middle of what was once called the "new red," or poikilitic group. the inferior half of this group will rank as primary or paleozoic, while its upper member will form the base of the secondary series. for the lower, or magnesian limestone division of english geologists, sir r. murchison has proposed the name of permian, from perm, a russian government where these strata are more extensively developed than elsewhere, occupying an area twice the size of france, and containing an abundant and varied suite of fossils. mr. king, in his valuable monograph, recently published, of the permian fossils of england, has given a table of the following six members of the permian system of the north of england, with what he conceives to be the corresponding formations in thuringia.[ -a] north of england. thuringia. . crystalline or concretionary, | . stinkstein. and non-crystalline limestone. | . brecciated and pseudo-brecciated | . rauchwacke. limestone. | . fossiliferous limestone. | . dolomit, or upper zechstein. . compact limestone. | . zechstein, or lower zechstein. . marl-slate. | . mergel-schiefer, or kupferschiefer. . inferior sandstones of various | . rothliegendes. colours. | i shall proceed, therefore, to treat briefly of these subdivisions, beginning with the highest, and referring the reader, for a fuller description of the lithological character of the whole group, as it occurs in the north of england, to a valuable memoir by professor sedgwick, published in .[ -a] _crystalline or concretionary limestone_ (no. .).--this formation is seen upon the coast of durham and yorkshire, between the wear and the tees. among its characteristic fossils are _schizodus schlotheimi_ (fig. .) and _mytilus septifer_ (fig. .). [illustration: fig. . _schizodus schlotheimi_, geinitz. syn. _axinus obscurus_, sow. crystalline limestone, permian.] [illustration: fig. . _schizodus truncatus_, king; to show hinge. permian.] [illustration: fig. . _mytilus septifer_, king. syn. _modiola acuminata_, james sow. permian crystalline limestone.] these shells occur at hartlepool and sunderland, where the rock assumes an oolitic and botryoidal character. some of the beds in this division are ripple-marked; and mr. king imagines that the absence of corals and the character of the shells indicate shallow water. in some parts of the coast of durham, where the rock is not crystalline, it contains as much as forty-four per cent. of carbonate of magnesia, mixed with carbonate of lime. in other places,--for it is extremely variable in structure,--it consists chiefly of carbonate of lime, and has concreted into globular and hemispherical masses, varying from the size of a marble to that of a cannon-ball, and radiating from the centre. occasionally earthy and pulverulent beds pass into compact limestone or hard granular dolomite. the stratification is very irregular, in some places well-defined, in others obliterated by the concretionary action which has re-arranged the materials of the rocks subsequently to their original deposition. examples of this are seen at pontefract and ripon in yorkshire. _the brecciated limestone_ (no. .) contains no fragments of foreign rocks, but seems composed of the breaking-up of the permian limestone itself, about the time of its consolidation. some of the angular masses in tynemouth cliff are feet in diameter. this breccia is considered by professor sedgwick as one of the forms of the preceding limestone, no. ., rather than as regularly underlying it. the fragments are angular and never water-worn, and appear to have been re-cemented on the spot where they were formed. it is, therefore, suggested that they may have been due to those internal movements of the mass which produced the concretionary structure; but the subject is very obscure, and after studying the phenomenon in the marston rocks, on the coast of durham, i found it impossible to form any positive opinion on the subject. the well-known brecciated limestones of the pyrenees appeared to me to present the nearest analogy, but on a much smaller scale. _the fossiliferous limestone_ (no. .) is regarded by mr. king as a deep-water formation, from the numerous delicate corals which it includes. one of these, _fenestella retiformis_ (fig. .), is a very variable species, and has received many different names. it sometimes attains a large size, measuring inches in width. the same zoophyte is also found abundantly in the permian of germany. [illustration: fig. . fenestella. _a._ _fenestella retiformis_, schlot. syn. _gorgonia infundibuliformis_, goldf.; _retepora flustracea_, phillips. _b._ part of the same highly magnified. magnesian limestone, humbleton hill, near sunderland.[ -a]] shells of the genera _spirifer_ and _productus_, which do not occur in strata newer than the permian, are abundant in this division of the series in the ordinary yellow magnesian limestone. (see figs. , .) [illustration: fig. . _productus calvus_, sow. min. con. syn. _productus horridus_, bronn's index, &c., king's monogr., &c.; _leptæna_, dalman. magnesian limestone.] [illustration: fig. . _spirifer undulatus_, sow. min. con. syn. _triogonotreta undulata_, king's monogr. magnesian limestone.] _the compact limestone_ (no. .) also contains organic remains, especially corallines, and is intimately connected with the preceding. beneath it lies the _marl-slate_ (no. .), which consists of hard, calcareous shales, marl-slate, and thin-bedded limestones. at east thickley, in durham, where it is thirty feet thick, this slate has yielded many fine specimens of fossil fish of the genera _palæoniscus_, _pygopterus_, _coelacanthus_, and _platysomus_, genera which are all found in the coal-measures of the carboniferous epoch, and which therefore, says mr. king, probably lived at no great distance from the shore. but the permian species are peculiar, and, for the most part, identical with those found in the marl-slate or copper-slate of thuringia. [illustration: fig. . restored outline of a fish of the genus _palæoniscus_, agass. _palæothrissum_, blainville.] the _palæoniscus_ above mentioned belongs to that division of fishes which m. agassiz has called "heterocercal," which have their tails unequally bilobate, like the recent shark and sturgeon, and the vertebral column running along the upper caudal lobe. (see fig. .) the "homocercal" fish, which comprise almost all the species at present known in the living creation, have the tail-fin either single or equally divided; and the vertebral column stops short, and is not prolonged into either lobe. (see fig. .) [illustration: fig. . shark. _heterocercal._] [illustration: fig. . shad. (_clupea_, herring tribe.) _homocercal._] now it is a singular fact, first pointed out by agassiz, that the heterocercal form, which is confined to a small number of genera in the existing creation, is universal in the magnesian limestone, and all the more ancient formations. it characterizes the earlier periods of the earth's history, when the organization of fishes made a greater approach to that of saurian reptiles than at later epochs. in all the strata above the magnesian limestone the homocercal tail predominates. a full description has been given by sir philip egerton of the species of fish characteristic of the marl-slate in mr. king's monograph before referred to, where figures of the ichthyolites which are very entire and well preserved, will be found. even a single scale is usually so characteristically marked as to indicate the genus, and sometimes even the particular species. they are often scattered through the beds singly, and maybe useful to a geologist in determining the age of the rock. [illustration: fig. . _palæoniscus comtus_, agassiz. scale magnified. marl-slate.] [illustration: fig. . _palæoniscus elegans_, sedg. under surface of scale magnified. marl-slate.] [illustration: fig. . _palæoniscus glaphyrus_, ag. under surface of scale magnified. marl-slate.] [illustration: fig. . _coelacanthus caudalis_, egerton. scale showing granulated surface magnified. marl-slate.] [ illustrations: scales of fish. magnesian limestone. fig. . _pygopterus mandibularis_, ag. marl-slate. _a._ outside of scale magnified. _b._ under surface of same. fig. . _acrolepis sedgwickii_, ag. marl-slate.] the _inferior sandstones_ (no. . tab. p. .), which lie beneath the marl-slate, consist of sandstone and sand, separating the magnesian limestone from the coal, in yorkshire and durham. in some instances, red marl and gypsum have been found associated with these beds. they have been classed with the magnesian limestone by professor sedgwick, as being nearly co-extensive with it in geographical range, though their relations are very obscure. in some regions we find it stated that the imbedded plants are all specifically identical with those of the carboniferous series; and, if so, they probably belong to that epoch; for the true permian flora appears, from the researches of mm. murchison and de verneuil in russia, and of colonel von gutbier in saxony, to be, with few exceptions, distinct from that of the coal (see p. .). _dolomitic conglomerate of bristol._--near bristol, in somersetshire, and in other counties bordering the severn, the unconformable beds of the lower new red, resting immediately upon the coal, consist of a conglomerate called "dolomitic," because the pebbles of older rocks are cemented together by a red or yellow base of dolomite or magnesian limestone. this conglomerate or breccia, for the imbedded fragments are sometimes angular, occurs in patches over the whole of the downs near bristol, filling up the hollows and irregularities in the mountain limestone, and being principally composed at every spot of the debris of those rocks on which it immediately rests. at one point we find pieces of coal shale, in another of mountain limestone, recognizable by its peculiar shells and zoophytes. fractured bones, also, and teeth of saurians, are dispersed through some parts of the breccia. these saurians (which until the discovery of the _archegosaurus_ in the coal were the most ancient examples of fossil reptiles) are all distinguished by having the teeth implanted deeply in the jaw-bone, and in distinct sockets, instead of being soldered, as in frogs, to a simple alveolar parapet. in the dolomitic conglomerate near bristol the remains of species of two distinct genera have been found, called _thecodontosaurus_ and _palæosaurus_ by dr. riley and mr. stutchbury[ -a]; the teeth of which are conical, compressed, and with finely serrated edges (figs. and .). [illustration: fig. . tooth of _palæosaurus_ platyodon, nat. size.] [illustration: fig. . tooth of _thecodontosaurus_, times magnified.] in russia, also, thecodont saurians occur, in beds of the permian age, of several genera, while others named _protorosaurus_ are met with in the zechstein of thuringia. this family of reptiles is allied to the living monitor, and its appearance in a primary or paleozoic formation, observes mr. owen, is opposed to the doctrine of the progressive development of reptiles from fish, or from simpler to more complex forms; for, if they existed at the present day, these monitors would take rank at the head of the lacertian order.[ -b] in russia the permian rocks are composed of white limestone, with gypsum and white salt; and of red and green grits, with occasionally copper ore; also magnesian limestones, marlstones, and conglomerates. the country of mansfeld, in thuringia, may be called the classic ground of the lower new red, or magnesian limestone, or permian formation, on the continent. it consists there principally of, first, the zechstein, corresponding to the upper portion of our english series; and, secondly, the marl-slate, with fish of species identical with those of the bed so called in durham. this slaty marlstone is richly impregnated with copper pyrites, for which it is extensively worked. magnesian limestone, gypsum, and rock-salt, occur among the superior strata of this group. at its base lies the rothliegendes, supposed to correspond with the inferior or lower new red sandstone above mentioned, which occupies a similar place in england between the marl-slate and coal. its local name of rothliegendes, _red-lyer_, or "roth-todt-liegendes," _red-dead-lyer_, was given by the workmen in the german mines from its red colour, and because the copper has _died out_ when they reach this rock, which is not metalliferous. it is, in fact, a great deposit of red sandstone and conglomerate, with associated porphyry, basaltic trap, and amygdaloid. _permian flora._--we learn from the recent investigation of colonel von gutbier, that in the permian rocks of saxony no less than sixty species of fossil plants have been met with, forty of which have not yet been found elsewhere. two or three of these, as _calamites gigas_, _sphenopteris erosa_, and _s. lobata_, are also met with in the government of perm in russia. seven others, and among them _neuropteris loshii_, _pecopteris arborescens_, and _p. similis_, with several species of _walchia_ (lycopodites), are common to the coal-measures. among the genera also enumerated by colonel gutbier are _asterophyllites_ and _annularia_, so characteristic of the carboniferous period; also _lepidodendron_, which is common to the permian of saxony, thuringia, and russia, although not abundant. _noeggerathia_ (see fig. .), supposed by a. brongniart to be allied to _cycas_, is another link between the permian and carboniferous vegetation. coniferæ, of the araucarian division, also occur; but these are likewise met with both in older and newer rocks. the plants called _sigillaria_ and _stigmaria_, so marked a feature in the carboniferous period, are as yet wanting. [illustration: fig. . _noeggerathia cuneifolia._ ad. brongniart.[ -a]] among the remarkable fossils of the rothliegendes, or lowest part of the permian in saxony and bohemia, are the silicified trunks of tree-ferns called generically _psaronius_. their bark was surrounded by a dense mass of air-roots, which often constituted a great addition to the original stem, so as to double or quadruple its diameter. the same remark holds good in regard to certain living extra-tropical arborescent ferns, particularly those of new zealand. psaronites are also found in the uppermost coal of autun in france, and in the upper coal-measures of the state of ohio in the united states, but specifically different from those of the rothliegendes. they serve to connect the permian flora with the more modern portion of the preceding or carboniferous group. upon the whole, it is evident that the permian plants approach nearer to the carboniferous ones than to the triassic; and the same may be said of the permian fauna. footnotes: [ -a] palæontographical society, , london. [ -a] trans. geol. soc. lond., second series, vol. iii. p. . [ -a] king's monograph, pl. . [ -a] see paper by messrs. riley and stutchbury, geol. trans., second series, vol. v. p. ., plate ., figures . and . [ -b] owen, report on reptiles, british assoc., eleventh meeting, , p. . [ -a] murchison's russia, vol. ii. pl. a. fig. . chapter xxiv. the coal, or carboniferous group. carboniferous strata in the south-west of england--superposition of coal-measures to mountain limestone--departure from this type in north of england and scotland--section in south wales--underclays with stigmaria--carboniferous flora--ferns, lepidodendra, calamites, asterophyllites, sigillariæ, stigmariæ--coniferæ--endogens--absence of exogens--coal, how formed--erect fossil trees--parkfield colliery--st. etienne, coal-field--oblique trees or snags--fossil forests in nova scotia--brackish water and marine strata--origin of clay-iron-stone. the next group which we meet with in the descending order is the carboniferous, commonly called "the coal;" because it contains many beds of that mineral, in a more or less pure state, interstratified with sandstones, shales, and limestones. the coal itself, even in great britain and belgium, where it is most abundant, constitutes but an insignificant portion of the whole mass. in the north of england, for example, the thickness of the coal-bearing strata has been estimated at feet, while the various coal-seams, or in number, do not in the aggregate exceed feet.[ -a] the carboniferous formation comprises two very distinct members: st, that usually called the coal-measures, of mixed freshwater, terrestrial, and marine origin, often including seams of coal; dly, that named in england the mountain or carboniferous limestone, of purely marine origin, and containing corals, shells, and encrinites. in the south-western part of our island, in somersetshire and south wales, the three divisions usually spoken of by english geologists are: . coal-measures { strata of shale, sandstone, and grit, with { occasional seams of coal, from to , { feet thick. . millstone grit { a coarse quartzose sandstone passing into a { conglomerate, sometimes used for millstones, with { beds of shale; usually devoid of coal; { occasionally above feet thick. . mountain or } a calcareous rock containing marine shells and carboniferous } corals; devoid of coal; thickness variable, limestone } sometimes feet. the millstone grit may be considered as one of the coal sandstones of coarser texture than usual, with some accompanying shales, in which coal plants are occasionally found. in the north of england some bands of limestone, with pectens, oysters, and other marine shells, occur in this grit, just as in the regular coal-measures, and even a few seams of coal. i shall treat, therefore, of the whole group, as consisting of two divisions only, the coal-measures and mountain limestone. the latter is found in the southern british coal-fields, at the base of the system, or immediately in contact with the subjacent old red sandstone; but as we proceed northwards to yorkshire and northumberland it begins to alternate with true coal-measures, the two deposits forming together a series of strata about feet in thickness. to this mixed formation succeeds the great mass of genuine mountain limestone.[ -a] farther north, in the fifeshire coal-field in scotland, we observe a still wider departure from the type of the south of england, or a more complete intercalation of dense masses of marine limestones with sandstones, and shales containing coal. coal-measures. in south wales the coal-measures have been ascertained by actual measurement to attain the extraordinary thickness of , feet, the beds throughout, with the exception of the coal itself, appearing to have been formed in water of moderate depth, during a slow but perhaps intermittent depression of the ground, in a region to which rivers were bringing a never-failing supply of muddy sediment and sand. the same area was sometimes covered with vast forests, such as we see in the deltas of great rivers in warm climates, which are liable to be submerged beneath fresh or salt water should the ground sink vertically a few feet. in one section near swansea, in south wales, where the total thickness of strata is feet, we learn from sir h. de la beche that there are ten principal masses of sandstone. one of these is feet thick, and the whole of them make together a thickness of feet. they are separated by masses of shale, varying in thickness from to feet. the intercalated coal-beds, sixteen in number, are generally from to feet thick, one of them, which has two or three layers of clay interposed, attaining feet.[ -b] at other points in the same coal-field the shales predominate over the sandstones. the horizontal extent of some seams of coal is much greater than that of others, but they all present one characteristic feature, in having, each of them, what is called its _underclay_. these underclays, co-extensive with every layer of coal, consist of arenaceous shale, sometimes called firestone, because it can be made into bricks which stand the fire of a furnace. they vary in thickness from inches to more than feet; and mr. logan first announced to the scientific world in that they were regarded by the colliers in south wales as an essential accompaniment of each of the one hundred seams of coal met with in their coal-field. they are said to form the _floor_ on which the coal rests; and some of them have a slight admixture of carbonaceous matter, while others are quite blackened by it. all of them, as mr. logan pointed out, are characterized by inclosing a peculiar species of fossil vegetable called _stigmaria_, to the exclusion of other plants. it was also observed that, while in the overlying shales or "roof" of the coal, ferns and trunks of trees abound without any _stigmariæ_, and are flattened and compressed, those singular plants in the underclays always retain their natural forms, branching freely, and sending out their slender leaves, as they were formerly styled, through the mud in all directions. several species of _stigmaria_ had long been known to botanists, and described by them, before their position under each seam of coal was pointed out. it was conjectured that they might be aquatic, perhaps floating plants, which sometimes extended their branches and leaves freely in fluid mud, and which were finally enveloped in the same mud. carboniferous flora. these statements will suffice to convince the reader that we cannot arrive at a satisfactory theory of the origin of coal till we understand the true nature of _stigmaria_; and in order to explain what is now known of this plant, and of others which have contributed by their decay to produce coal, it will be necessary to offer a brief preliminary sketch of the whole carboniferous flora, an assemblage of fossil plants, with which we are better acquainted than with any other which flourished antecedently to the tertiary epoch. it should also be remarked that göppert has ascertained that the remains of every family of plants scattered through the coal-measures are sometimes met with in the pure coal itself, a fact which adds greatly to the geological interest attached to this flora. _ferns._--the number of species of carboniferous plants hitherto described amounts, according to m. ad. brongniart, to about . these may perhaps be a fragment only of the entire flora, but they are enough to show that the state of the vegetable world was then extremely different from that now established. we are struck at the first glance with the similarity of many of the ferns to those now living, and the dissimilarity of almost all the other fossils except the coniferæ. among the ferns, as in the case of _pecopteris_ for example (fig. .), it is not always easy to decide whether they should be referred to different genera from those established for the classification of living species; whereas, in regard to most of the other contemporary tribes, with the exception of the coniferæ, it is often difficult to guess the family, or even the class, to which they belong. the ferns of the carboniferous period are generally without organs of fructification, but in some specimens these are well preserved. in the general absence of such characters, they have been divided into genera, distinguished chiefly by the branching of the fronds, and the way in which the veins of the leaves are disposed. the larger portion are supposed to have been of the size of ordinary european ferns, but some were decidedly arborescent, especially the group called _caulopteris_, by lindley, and the _psaronius_ of the upper or newest coal-measures, before alluded to (p. .). [illustration: fig. . _pecopteris lonchitica._ (foss. flo. .)] [illustration: fig. . sphenopteris. (foss. flo. .) _a._ _sphenopteris crenata._ _b._ the same, magnified.] [illustration: fig. . _caulopteris primæva_, lindley.] all the recent tree-ferns belong to one tribe (_polypodiaceæ_), and to a small number only of genera in that tribe, in which the surface of the trunk is marked with scars, or cicatrices, left after the fall of the fronds. these scars resemble those of _caulopteris_ (see fig. .). no less than ferns have already been obtained from the coal strata; and even if we make some reduction on the ground of varieties which have been mistaken, in the absence of their fructification, for species, still the result is singular, because the whole of europe affords at present no more than indigenous species. [ illustrations: living tree-ferns of different genera. (ad. brong.) fig. . tree-fern from isle of bourbon. fig. . _cyathea glauca_, mauritius. fig. . tree fern from brazil.] [ illustrations: _lepidodendron sternbergii._ coal-measures, near newcastle. fig. . branching trunk, feet long, supposed to have belonged to _l. sternbergii_. (foss. flo. .) fig. . branching stem with bark and leaves of _l. sternbergii_. (foss. flo. .) fig. . portion of same nearer the root; natural size. (ibid.)] _lepidodendra._--these fossils belong to the family of _lycopodiums_, yet most of them grew to the size of large trees. the annexed figures represent a large fossil _lepidodendron_, feet long, found in jarrow colliery, near newcastle, lying in shale parallel to the planes of stratification. fragments of others, found in the same shale, indicate, by the size of the rhomboidal scars which cover them, a still greater magnitude. the living club-mosses, of which there are about species, are abundant in tropical climates, where one species is sometimes met with attaining a height of feet. they usually creep on the ground, but some stand erect, as the _l. densum_, from new zealand (fig. .). [illustration: fig. . lycopodium. _a._ _lycopodium densum_; banks of r. thames, new zealand. _b._ branch, natural size. _c._ part of same, magnified.] in the carboniferous strata of coalbrook dale, and in many other coal-fields, elongated cylindrical bodies, called fossil cones, named by m. adolphe brongniart _lepidostrobus_, are met with. (see fig. .) they often form the nucleus of concretionary balls of clay-iron-stone, and are well preserved, exhibiting a conical axis, around which a great quantity of scales were compactly imbricated. the opinion of m. brongniart is now generally adopted, that the _lepidostrobus_ is the fruit of _lepidodendron_. [illustration: fig. . _lepidostrobus ornatus_, brong.; half nat. size. shropshire.] [illustration: fig. . _calamites cannæformis_, schlot. (foss. flo. .) lower end with rootlets.] [illustration: fig. . _calamites suckowii_, brong.; natural size. common in coal throughout europe.] _equisetaceæ._--to this family belong two species of the genus _equisetites_, allied to the living "horse-tail" which now grows in marshy grounds. other species, which have jointed stems, depart more widely from _equisetum_, but are yet of analogous organization. they differed from it principally in being furnished with a thin bark, which is represented in the stem of _c. suckowii_ (fig. .), in which it will be seen that the striped external pattern does not agree with that left on the stone where the bark is stripped off; so that if the two impressions were seen separately, they might be mistaken for two distinct species. the tallest living "horse-tails" are only or feet high in europe, and even in tropical climates only attain, as in the case of _equisetum giganteum_, discovered by humboldt and bonpland, in south america, a height of about feet, the stem being an inch in diameter. several of the calamites of the coal acquired the height and dimensions of small trees. [illustration: fig. . _asterophyllites foliosa._ (foss. flo. .) coal-measures, newcastle.] _asterophyllites._--in this family, m. brongniart includes several genera, and among them _calamodendron_, _asterophyllites_, and _annularia_. the graceful plant, represented in the annexed figure, is supposed to be the branch of a shrub called _calamodendron_, a new genus, divided off by brongniart from the _calamites_ of former authors. its pith and medullary rays seem to show that it was dicotyledonous, and it appears to have been allied, by the nature of its tissue, to the gymnogens, or, still more, to the _sigillaria_, which will next be mentioned. _sigillaria._--a large portion of the trees of the carboniferous period belonged to this genus, of which about thirty-five species are known. the structure, both internal and external, was very peculiar, and, with reference to existing types, very anomalous. they were formerly referred, by m. ad. brongniart, to ferns, which they resemble in the scalariform texture of their vessels, and, in some degree, in the form of the cicatrices left by the base of the leafstalks which have fallen off (see fig. .). but with these points of analogy to cryptogamia, they combine an internal organization much resembling that of cycads, and some of them are ascertained to have had long linear leaves, quite unlike those of ferns. they grew to a great height, from to , or even feet, with regular cylindrical stems, and without branches, although some species were dichotomous towards the top. their fluted trunks, from to feet in diameter, appear to have decayed rapidly in the interior, so as to become hollow, when standing; when, therefore, they were thrown prostrate on the mud, they were squeezed down and flattened. hence, we find the bark of the two opposite sides (now converted into bright shining coal) to constitute two horizontal layers, one upon the other, half an inch, or an inch, in thickness. these same trunks, when they are placed obliquely or vertically to the planes of stratification, retain their original rounded form, and are uncompressed, the cylinder of bark having been filled with sand, which now affords a cast of the interior. [illustration: fig. . _sigillaria lævigata_, brong.] _stigmaria._--this fossil, the importance of which has already been pointed out, was formerly conjectured to be an aquatic plant. it is now ascertained to be the root of _sigillaria_. the connection of the roots with the stem, previously suspected, on botanical grounds, by brongniart, was first proved, by actual contact, in the lancashire coal-field, by mr. binney. the fact has lately been shown, even more distinctly, by mr. richard brown, in his description of the _stigmariæ_ occurring in the underclays of the coal-seams of the island of cape breton, in nova scotia. [illustration: fig. . stigmaria attached to a trunk of _sigillaria_.[ -a]] in a specimen of one of these, represented in the annexed figure (fig. .), the spread of the roots was feet, and some of them sent out rootlets, in all directions, into the surrounding clay. the manner of attachment of the fibres to the stem resembles that of a ball and socket joint, the base of each rootlet being concave, and fitting on to a tubercle (see figs. and .). rows of these tubercles are arranged spirally round each root, which have always a medullary cavity and woody texture, much resembling that of _sigillaria_, the structure of the vessels being, like it, scalariform. [illustration: fig. . surface of another individual of same species, showing form of tubercles. (foss. flo. .)] [illustration: fig. . _stigmaria ficoides_, brong. one fourth of nat. size. (foss. flo. .)] _conifers._--the coniferous trees of this period are referred to five genera; the woody structure of some of them showing that they were allied to the araucarian division of pines, more than to any of our common european firs. some of their trunks exceeded feet in height. _endogens._--hitherto but few monocotyledonous plants have been discovered in the coal-strata. most of these consist of fruits referred by some botanists to palms. the three-sided nuts, called _trigonocarpum_, seven species of which are known, appear to have the best claim to rank as palms, although m. ad. brongniart entertains some doubt even as to their being monocotyledons. _exogens._ the entire absence, so far as our paleontological investigations have hitherto gone, of ordinary dicotyledons or exogens in the coal measures, is most remarkable. hence, m. adolphe brongniart has called this period the age of acrogens, in consequence of the vast preponderance of ferns and _lepidodendra_.[ -a] nevertheless, a forest of the period, now under consideration, may have borne a considerable resemblance to those woody regions of new zealand, in which ferns, arborescent and herbaceous, and lycopodiums, with many coniferæ, abound. the comparative proportion of living ferns and _araucariæ_, in norfolk island, to all the other plants, appears to be very similar to that formerly borne by these tribes respectively in a forest of the coal-period. i have already stated that professor göppert, after examining the fossil vegetables of the coal-fields of germany, has detected, in beds of pure coal, remains of plants of every family hitherto known to occur fossil in the coal. many seams, he remarks, are rich in _sigillaria_, _lepidodendron_, and _stigmaria_, the latter in such abundance, as to appear to form the bulk of the coal. in some places, almost all the plants are calamites, in others ferns.[ -b] _coal, how formed--erect trees._--i shall now consider the manner in which the above-mentioned plants are imbedded in the strata, and how they may have contributed to produce coal. "some of the plants of our coal," says dr. buckland, "grew on the identical banks of sand, silt, and mud, which, being now indurated to stone and shale, form the strata that accompany the coal; whilst other portions of these plants have been drifted to various distances from the swamps, savannahs, and forests that gave them birth, particularly those that are dispersed through the sandstones, or mixed with fishes in the shale beds." "at balgray, three miles north of glasgow," says the same author, "i saw in the year , as there still may be seen, an unequivocal example of the stumps of several stems of large trees, standing close together in their native place, in a quarry of sandstone of the coal formation."[ -a] between the years and , six fossil trees were discovered in the coal-field of lancashire, where it is intersected by the bolton railway. they were all in a vertical position, with respect to the plane of the bed, which dips about ° to the south. the distance between the first and the last was more than feet, and the roots of all were imbedded in a soft argillaceous shale. in the same plane with the roots is a bed of coal, eight or ten inches thick, which has been ascertained to extend across the railway, or to the distance of at least ten yards. just above the covering of the roots, yet beneath the coal seam, so large a quantity of the _lepidostrobus variabilis_ was discovered inclosed in nodules of hard clay, that more than a bushel was collected from the small openings around the base of the trees (see figure of this genus, p. .). the exterior trunk of each was marked by a coating of friable coal, varying from one quarter to three quarters of an inch in thickness; but it crumbled away on removing the matrix. the dimensions of one of the trees is - / feet in circumference at the base, - / feet at the top, its height being feet. all the trees have large spreading roots, solid and strong, sometimes branching, and traced to a distance of several feet, and presumed to extend much farther. mr. hawkshaw, who has described these fossils, thinks that, although they were hollow when submerged, they may have consisted originally of hard wood throughout; for solid dicotyledonous trees, when prostrated in tropical forests, as in venezuela, on the shore of the caribbean sea, were observed by him to be destroyed in the interior, so that little more is left than an outer shell, consisting chiefly of the bark. this decay, he says, goes on most rapidly in low and flat tracks, in which there is a deep rich soil and excessive moisture, supporting tall forest-trees and large palms, below which bamboos, canes, and minor palms flourish luxuriantly. such tracts, from their lowness, would be most easily submerged, and their dense vegetation might then give rise to a seam of coal.[ -b] in a deep valley near capel-coelbren, branching from the higher part of the swansea valley, four stems of upright _sigillariæ_ were seen, in , piercing through the coal-measures of s. wales; one of them was feet in diameter, and one feet and a half high, and they were all found to terminate downwards in a bed of coal. "they appear," says sir h. de la beche, "to have constituted a portion of a subterranean forest at the epoch when the lower carboniferous strata were formed.[ -a] in a colliery near newcastle, say the authors of the fossil flora, a great number of _sigillariæ_ were placed in the rock as if they had retained the position in which they grew. not less than thirty, some of them or feet in diameter, were visible within an area of yards square, the interior being sandstone, and the bark having been converted into coal. the roots of one individual were found imbedded in shale; and the trunk, after maintaining a perpendicular course and circular form for the height of about feet, was then bent over so as to become horizontal. here it was distended laterally, and flattened so as to be only one inch thick, the flutings being comparatively distinct.[ -b] such vertical stems are familiar to our miners, under the name of coal-pipes. one of them, feet in length, was discovered, in , near gosforth, about five miles from newcastle, in coal-grit, the strata of which it penetrated. the exterior of the trunk was marked at intervals with knots, indicating the points at which branches had shot off. the wood of the interior had been converted into carbonate of lime; and its structure was beautifully shown by cutting transverse slices, so thin as to be transparent. (see p. .) these "coal-pipes" are much dreaded by our miners, for almost every year in the bristol, newcastle, and other coal-fields, they are the cause of fatal accidents. each cylindrical cast of a tree, formed of solid sandstone, and increasing gradually in size towards the base, and being without branches, has its whole weight thrown downwards, and receives no support from the coating of friable coal which has replaced the bark. as soon, therefore, as the cohesion of this external layer is overcome, the heavy column falls suddenly in a perpendicular or oblique direction from the roof of the gallery whence coal has been extracted, wounding or killing the workman who stands below. it is strange to reflect how many thousands of these trees fell originally in their native forests in obedience to the law of gravity; and how the few which continued to stand erect, obeying, after myriads of ages, the same force, are cast down to immolate their human victims. it has been remarked, that if, instead of working in the dark, the miner was accustomed to remove the upper covering of rock from each seam of coal, and to expose to the day the soils on which ancient forests grew, the evidence of their former growth would be obvious. thus in south staffordshire a seam of coal was laid bare in the year , in what is called an open work at parkfield colliery, near wolverhampton. in the space of about a quarter of an acre the stumps of no less than trees with their roots attached appeared, as shown in the annexed plan (fig. .), some of them more than feet in circumference. the trunks, broken off close to the root, were lying prostrate in every direction, often crossing each other. one of them measured , another feet in length, and others less. they were invariably flattened to the thickness of one or two inches, and converted into coal. their roots formed part of a stratum of coal inches thick, which rested on a layer of clay inches thick, below which was a second forest, resting on a -foot seam of coal. five feet below this again was a third forest with large stumps of _lepidodendra_, _calamites_, and other trees. [illustration: fig. . ground-plan of a fossil forest, parkfield colliery, near wolverhampton, showing the position of trees in a quarter of an acre.[ -a]] in the account given, in , by m. alex. brongniart of the coal-mine of treuil, at st. etienne, near lyons, he states, that distinct horizontal strata of micaceous sandstone are traversed by vertical trunks of monocotyledonous vegetables, resembling bamboos or large _equiseta_.[ -b] since the consolidation of the stone, there has been here and there a sliding movement, which has broken the continuity of the stems, throwing the upper parts of them on one side, so that they are often not continuous with the lower. from these appearances it was inferred that we have here the monuments of a submerged forest. i formerly objected to this conclusion, suggesting that, in that case, all the roots ought to have been found at one and the same level, and not scattered irregularly through the mass. i also imagined that the soil to which the roots were attached should have been different from the sandstone in which the trunks are enclosed. having, however, seen calamites near pictou, in nova scotia, buried at various heights in sandstone and in similar erect attitudes, i have now little doubt that m. brongniart's view was correct. these plants seem to have grown on a sandy soil, liable to be flooded from time to time, and raised by new accessions of sediment, as may happen in swamps near the banks of a large river in its delta. trees which delight in marshy grounds are not injured by being buried several feet deep at their base; and other trees are continually rising up from new soils, several feet above the level of the original foundation of the morass. in the banks of the mississippi, when the water has fallen, i have seen sections of a similar deposit in which portions of the stumps of trees with their roots _in situ_ appeared at many different heights.[ -a] [illustration: fig. . section showing the erect position of fossil trees in coal sandstone at st. etienne. (alex. brongniart.)] when i visited, in , the quarries of treuil above-mentioned, the fossil trees seen in fig. . were removed, but i obtained proofs of other forests of erect trees in the same coal-field. [illustration: fig. . inclined position of a fossil tree, cutting through horizontal beds of sandstone, craigleith quarry, edinburgh. angle of inclination from _a_ to _b_ °.] _snags._--in , a slanting trunk was exposed in craigleith quarry, near edinburgh, the total length of which exceeded feet. its diameter at the top was about inches, and near the base it measured feet in its greater, and feet in its lesser width. the bark was converted into a thin coating of the purest and finest coal, forming a striking contrast in colour with the white quartzose sandstone in which it lay. the annexed figure represents a portion of this tree, about feet long, which i saw exposed in , when all the strata had been removed from one side. the beds which remained were so unaltered and undisturbed at the point of junction, as clearly to show that they had been tranquilly deposited round the tree, and that the tree had not subsequently pierced through them, while they were yet in a soft state. they were composed chiefly of siliceous sandstone, for the most part white; and divided into laminæ so thin, that from six to fourteen of them might be reckoned in the thickness of an inch. some of these thin layers were dark, and contained coaly matter; but the lowest of the intersected beds were calcareous. the tree could not have been hollow when imbedded, for the interior still preserved the woody texture in a perfect state, the petrifying matter being, for the most part, calcareous.[ -a] it is also clear, that the lapidifying matter was not introduced laterally from the strata through which the fossil passes, as most of these were not calcareous. it is well known that, in the mississippi and other great american rivers, where thousands of trees float annually down the stream, some sink with their roots downwards, and become fixed in the mud. thus placed, they have been compared to a lance in rest; and so often do they pierce through the bows of vessels which run against them, that they render the navigation extremely dangerous. mr. hugh miller mentions four other huge trunks exposed in quarries near edinburgh, which lay diagonally across the strata at an angle of about °, with their lower or heavier portions downwards, the roots of all, save one, rubbed off by attrition. one of these was and another feet in length, and from to feet in diameter. [illustration: fig. . section of the cliffs of the south joggins, near minudie, nova scotia.] the number of years for which the trunks of trees, when constantly submerged, can resist decomposition, is very great; as we might suppose from the durability of wood, in artificial piles, permanently covered by water. hence these fossil snags may not imply a rapid accumulation of beds of sand, although the channel of a river or part of a lagoon is often filled up in a very few years. _nova scotia._--one of the finest examples in the world of a succession of fossil forests of the carboniferous period, laid open to view in a natural section, is that seen in the lofty cliffs bordering the chignecto channel, a branch of the bay of fundy, in nova scotia.[ -b] in the annexed section (fig. .), which i examined in july, , the beds from _c_ to _i_ are seen all dipping the same way, their average inclination being at an angle of ° s.s.w. the vertical height of the cliffs is from to feet; and between _d_ and _g_, in which space i observed seventeen trees in an upright position, or, to speak more correctly, at right angles to the planes of stratification, i counted nineteen seams of coal, varying in thickness from inches to feet. at low tide a fine horizontal section of the same beds is exposed to view on the beach. the thickness of the beds alluded to, between _d_ and _g_, is about , feet, the erect trees consisting chiefly of large _sigillariæ_, occurring at ten distinct levels, one above the other; but mr. logan, who afterwards made a more detailed survey of the same line of cliffs, found erect trees at seventeen levels, extending through a vertical thickness of , feet of strata; and he estimated the total thickness of the carboniferous formation, with and without coal, at no less than , feet, every where devoid of marine organic remains.[ -a] the usual height of the buried trees seen by me was from to feet; but one trunk was about feet high and feet in diameter, with a considerable bulge at the base. in no instance could i detect any trunk intersecting a layer of coal, however thin; and most of the trees terminated downwards in seams of coal. some few only were based in clay and shale, none of them in sandstone. the erect trees, therefore, appeared in general to have grown on beds of coal. in some of the underclays i observed _stigmaria_. [illustration: fig. . fossil tree at right angles to planes of stratification. coal measures, nova scotia.] in regard to the plants, they belonged to the same genera, and most of them to the same species, as those met with in the distant coal-fields of europe. in the sandstone, which filled their interiors, i frequently observed fern leaves, and sometimes fragments of _stigmaria_, which had evidently entered together with sediment after the trunk had decayed and become hollow, and while it was still standing under water. thus the tree, _a b_, fig. ., the same which is represented at _a_, fig. ., or in the bed _e_ in the larger section, fig. ., is a hollow trunk feet inches in length, traversing various strata, and cut off at the top by a layer of clay feet thick on which rests a seam of coal (_b_, fig. .) foot thick. on this coal again stood two large trees (_c_ and _d_), while at a greater height the trees _f_ and _g_ rest upon a thin seam of coal (_e_), and above them is an underclay, supporting the -foot coal. [illustration: fig. . erect fossil trees. coal-measures, nova scotia.] if we now return to the tree first mentioned (fig. .), we find the diameter (_a b_) inches at the top and inches at the bottom, the length of the trunk feet inches. the strata in the interior consisted of a series entirely different from those on the outside. the lowest of the three outer beds which it traversed consisted of purplish and blue shale (_c_, fig. .), feet thick, above which was sandstone (_d_) foot thick, and, above this, clay (_e_) feet inches. but, in the interior, were nine distinct layers of different composition: at the bottom, first, shale inches, then sandstone foot, then shale inches, then sandstone inches, then shale inches, then clay (_f_) with nodules of ironstone inches, then pure clay feet, then sandstone inches, and, lastly, clay inches. owing to the outward slope of the face of the cliff, the section (fig. .) was not exactly perpendicular to the axis of the tree; and hence, probably, the apparent sudden termination at the base without a stump and roots. in this example the layers of matter in the inside of the tree are more numerous than those without; but it is more common in the coal-measures of all countries to find a cylinder of pure sandstone,--the cast of the interior of a tree, intersecting a great many alternating beds of shale and sandstone, which originally enveloped the trunk as it stood erect in the water. such a want of correspondence in the materials outside and inside, is just what we might expect if we reflect on the difference of time at which the deposition of sediment will take place in the two cases; the imbedding of the tree having gone on for many years before its decay had made much progress. the high tides of the bay of fundy, rising more than feet, are so destructive as to undermine and sweep away continually the whole face of the cliffs, and thus a new crop of erect trees is brought into view every three or four years. they are known to extend over a space between two and three miles from north to south, and more than twice that distance from east to west, being seen in the banks of streams intersecting the coal-field. in cape breton, mr. richard brown has observed in the sydney coal-field a total thickness of coal-measures, without including the underlying millstone grit, of feet, dipping at an angle of °. he has published minute details of the whole series, showing at how many different levels erect trees occur, consisting of _sigillaria_, _lepidodendron_, _calamite_, and other genera. in one place eight erect trunks, with roots and rootlets attached to them, were seen at the same level, within a horizontal space feet in length. beds of coal of various thickness are interstratified. some of the associated strata are ripple-marked, with impressions of rain-drops. taking into account forty-one clays filled with roots of _stigmaria_ in their natural position, and eighteen layers of upright trees at other levels, there is, on the whole, clear evidence of at least fifty-nine fossil forests, ranged one above the other, in this coal-field, in the above-mentioned thickness of strata.[ -a] the fossil shells in cape breton and in the nova scotia section (fig. .), consisting of _cypris_, _unio_ (?), _modiola_, _microconchus carbonarius_ (see fig. .), and _spirorbis_, seem to indicate brackish water; but we ought never to be surprised if, in pursuing the same stratum, we come to a fresh or purely marine deposit; for this will depend upon our taking a direction higher up or lower down the ancient river or delta deposit. when the purbeck beds of the wealden were described in chap. xviii., i endeavoured to explain the intimate connection of strata formed at a river's mouth, or in the tranquil lagoons of the delta, or in the sea, after a slight submergence of the land, with its dirt-beds. in the english coal-fields the same association of fresh, or rather brackish water with marine strata, in close connection with beds of coal of terrestrial origin, has been frequently recognized. thus, for example, a deposit near shrewsbury, probably formed in brackish water, has been described by sir r. murchison as the youngest member of the carboniferous series of that district, at the point where the coal-measures are in contact with the permian or "lower new red." it consists of shales and sandstones about feet thick, with coal and traces of plants; including a bed of limestone, varying from to feet in thickness, which is cellular, and resembles some lacustrine limestones of france and germany. it has been traced for miles in a straight line, and can be recognized at still more distant points. the characteristic fossils are a small bivalve, having the form of a _cyclas_, a small _cypris_ (fig. .), and the microscopic shell of an annelid of an extinct genus called _microconchus_ (fig. .), allied to _serpula_ or _spirorbis_. in the lower coal-measures of coalbrook dale, the strata, according to mr. prestwich, often change completely within very short distances, beds of sandstone passing horizontally into clay, and clay into sandstone. the coal-seams often wedge out or disappear; and sections, at places nearly contiguous, present marked lithological distinctions. in this single field, in which the strata are from to feet thick, between forty and fifty species of terrestrial plants have been discovered, besides several fishes and trilobites of forms distinct from those occurring in the silurian strata. also upwards of forty species of mollusca, among which are two or three referred to the freshwater genus _unio_, and others of marine forms, such as _nautilus_, _orthoceras_, _spirifer_, and _productus_. mr. prestwich suggests that the intermixture of beds containing freshwater shells with others full of marine remains, and the alternation of coarse sandstone and conglomerate with beds of fine clay or shale containing the remains of plants, may be explained by supposing the deposit of coalbrook dale to have originated in a bay of the sea or estuary into which flowed a considerable river subject to occasional freshes.[ -a] [ illustrations: freshwater fossils--coal. fig. . _a._ _microconchus carbonarius_. _b._ var. of same; nat. size, and magnified. fig. . _cypris inflata_, natural size, and magnified. murchison.[ -b]] in the edinburgh coal-field, at burdiehouse, fossil fishes, mollusca, and cypris, very similar to those in shropshire and staffordshire, have been found by dr. hibbert.[ -c] in the coal-field also of yorkshire there are freshwater strata, some of which contain shells referred to the genus _unio_; but in the midst of the series there is one thin but very widely spread stratum, abounding in fishes and marine shells, such as _ammonites listeri_ (fig. .), _orthoceras_, and _avicula papyracea_, goldf. (fig. .)[ -d] [illustration: fig. . _ammonites listeri_, sow.] [illustration: fig. . _avicula papyracea_, goldf. (_pecten papyraceus_, sow.)] no similarly intercalated layer of marine shells has been noticed in the neighbouring coal-field of newcastle, where, as in south wales and somersetshire, the marine deposits are entirely below those containing terrestrial and freshwater remains.[ -a] _clay-iron-stone._--bands and nodules of clay-iron-stone are common in coal-measures, and are formed, says sir h. de la beche, of carbonate of iron, mingled mechanically with earthy matter, like that constituting the shales. mr. hunt, of the museum of practical geology, instituted a series of experiments to illustrate the production of this substance, and found that decomposing vegetable matter, such as would be distributed through all coal strata, prevented the farther oxidation of the proto-salts of iron, and converted the peroxide into protoxide by taking a portion of its oxygen to form carbonic acid. such carbonic acid, meeting with the protoxide of iron in solution, would unite with it and form a carbonate of iron; and this mingling with fine mud, when the excess of carbonic acid was removed, might form beds or nodules of argillaceous iron-stone.[ -b] footnotes: [ -a] phillips; art. "geology," encyc. britan. [ -a] sedgwick, geol. trans., second series, vol. iv.; and phillips, geol. of yorksh. part . [ -b] memoirs of geol. survey, vol. i. p. . [ -a] the trunk in this case is referred by mr. brown to _lepidodendron_, but his illustrations seem to show the usual markings assumed by _sigillaria_ near its base. [ -a] for terminology of classification of plants, see above, note, p. . [ -b] quart. geol. journ., vol. v., mem., p. . [ -a] anniv. address to geol. soc., . [ -b] hawkshaw, geol. soc. proceedings, nos. . and . [ -a] geol. report on cornwall, &c. p. . [ -b] lindley and hutton, foss. flo. part . p. . [ -a] see papers by messrs. beckett and ick. proceed. in geol. soc., vol. iv. p. . [ -b] annales des mines, . [ -a] principles of geol., th ed., p. . [ -a] see figures of texture, witham, foss. veget., pl. . [ -b] see lyell's travels in n. america, vol. ii. p. . [ -a] quart. geol. journ., vol. ii. p. . [ -a] geol. quart. journ., vol. ii. p. .; and vol. vi. p. . [ -a] prestwich, geol. trans., d series, vol. v. p. . murchison, silurian system, p. . [ -b] silurian system, p. . [ -c] trans. roy. soc. edin. vol. xiii. horner, edin. new phil. journ., april, . [ -d] phillips; art. "geology," encyc. metrop., p. . [ -a] phillips; art. "geology," encyc. metrop., p. . [ -b] memoirs of geol. survey, pp. . , &c. chapter xxv. carboniferous group--_continued_. coal-fields of the united states--section of the country between the atlantic and mississippi--position of land in the carboniferous period eastward of the alleghanies--mechanically formed rocks thinning out westward, and limestones thickening--uniting of many coal-seams into one thick one--horizontal coal at brownsville, pennsylvania--vast extent and continuity of single seams of coal--ancient river-channel in forest of dean coal-field--absence of earthy matter in coal--climate of carboniferous period--insects in coal--rarity of air-breathing animals--great number of fossil fish--first discovery of the skeletons of fossil reptiles--footprints of reptilians--mountain limestone--its corals and marine shells. it was stated in the last chapter that a great uniformity prevails in the fossil plants of the coal-measures of europe and north america; and i may add that four-fifths of those collected in nova scotia have been identified with european species. hence the former existence at the remote period under consideration (the carboniferous) of a continent or chain of islands where the atlantic now rolls its waves seems a fair inference. nor are there wanting other and independent proofs of such an ancient land situated to the eastward of the present atlantic coast of north america; for the geologist deduces the same conclusion from the mineral composition of the carboniferous and some older groups of rocks as they are developed on the eastern flanks of the alleghanies, contrasted with their character in the low country to the westward of those mountains. the annexed diagram (fig. .) will assist the reader in understanding the phenomena now alluded to, although i must guard him against supposing that it is a true section. a great number of details have of necessity been omitted, and the scale of heights and horizontal distances are unavoidably falsified. [illustration: fig. . diagram explanatory of the geological structure of a part of the united states between the atlantic and the mississippi. length from e. to w. miles. appalachian coal field. alleghanies, or appalachians. same section--_continued_. mississippi. illinois coal field. cincinnati. appalachian coal field. a b. atlantic plain. b c. atlantic slope. c d. alleghanies or appalachian chain. d e. appalachian coal-field west of the mountains. e f. dome-shaped outcrop of strata on the ohio, older than the coal. f g. illinois coal-field. _h._ falls and rapids of the rivers at the junction of the hypogene and newer formations. _i_, _k_, _l_, _m_. parallel folds of appalachians becoming successively more open, and flatter in going from e. to w. _references to the different formations._ . miocene tertiary. . eocene tertiary. . cretaceous strata. . red sandstone with ornithichnites (new red or trias?) usually much invaded by trap. . coal-measures (bituminous coal). ' anthracitic coal-measures. '' carboniferous limestone of the illinois coal-field, wanting in the appalachian. . old red or devonian, olive slate, &c. . primary fossiliferous or silurian strata. . hypogene strata, or gneiss, mica schist, &c., with granite veins. _note._ the dotted lines at _i_ and _k_ express portions of rock removed by denudation, the amount of which may be estimated by supposing similar lines prolonged from other points where different strata end abruptly at the surface. _n.b._ the lower section at ** joins on to the upper one at *.] starting from the shores of the atlantic, on the eastern side of the continent, we first come to a low region (a b), which was called the alluvial plain by the first geographers. it is occupied by tertiary and cretaceous strata, before described (pp. . . and .), which are nearly horizontal. the next belt, from b to c, consists of granitic rocks (hypogene), chiefly gneiss and mica-schist, covered occasionally with unconformable red sandstone, no. . (new red or trias?), remarkable for its ornithichnites (see p. .). sometimes, also, this sandstone rests on the edges of the disturbed paleozoic rocks (as seen in the section). the region (b c), sometimes called the "atlantic slope," corresponds nearly in average width with the low and flat plain (a, b), and is characterized by hills of moderate height, contrasting strongly, in their rounded shape and altitude, with the long, steep, and lofty parallel ridges of the alleghany mountains. the outcrop of the strata in these ridges, like the two belts of hypogene and newer rocks (a b, and b c), above alluded to, when laid down on a geological map, exhibit long stripes of different colours, running in a n.e. and s.w. direction, in the same way as the lias, chalk, and other secondary formations in the middle and eastern half of england. the narrow and parallel zones of the appalachians here mentioned, consist of strata, folded into a succession of convex and concave flexures, subsequently laid open by denudation. the component rocks are of great thickness, all referable to the silurian, devonian, and carboniferous formations. there is no principal or central axis, as in the pyrenees and many other chains--no nucleus to which all the minor ridges conform; but the chain consists of many nearly equal and parallel foldings, having what is termed an anticlinal and synclinal arrangement (see above, p. .). this system of hills extends, geologically considered, from vermont to alabama, being more than miles long, from to miles broad, and varying in height from to feet. sometimes the whole assemblage of ridges runs perfectly straight for a distance of more than miles, after which all of them wheel round together, and take a new direction, at an angle of or degrees to the first. we are indebted to the state surveyors of virginia and pennsylvania, prof. w. b. rogers and his brother prof. h. d. rogers, for the important discovery of a clue to the general law of structure prevailing throughout this range of mountains, which, however simple it may appear when once made out and clearly explained, might long have been overlooked; amidst so great a mass of complicated details. it appears that the bending and fracture of the beds is greatest on the south-eastern or atlantic side of the chain, and the strata become less and less disturbed as we go westward, until at length they regain their original or horizontal position. by reference to the section (fig. .), it will be seen that on the eastern side, or in the ridges and troughs nearest the atlantic, south-eastern dips predominate, in consequence of the beds having been folded back upon themselves, as in _i_, those on the north-western side of each arch having been inverted. the next set of arches (such as _k_) are more open, each having its western side steepest; the next (_l_) opens out still more widely, the next (_m_) still more, and this continues until we arrive at the low and level part of the appalachian coal-field (d e). in nature or in a true section, the number of bendings or parallel folds is so much greater that they could not be expressed in a diagram without confusion. it is also clear that large quantities of rock have been removed by aqueous action or denudation, as will appear if we attempt to complete all the curves in the manner indicated by the dotted lines at _i_ and _k_. the movements which imparted so uniform an order of arrangement to this vast system of rocks must have been, if not contemporaneous, at least parts of one and the same series, depending on some common cause. their geological date is well defined, at least within certain limits, for they must have taken place after the deposition of the carboniferous strata (no. .), and before the formation of the red sandstone (no. .). the greatest disturbing and denuding forces have evidently been exerted on the south-eastern side of the chain; and it is here that igneous or plutonic rocks are observed to have invaded the strata, forming dykes, some of which run for miles in lines parallel to the main direction of the appalachians, or n.n.e. and s.s.w. the thickness of the carboniferous rocks in the region c is very great, and diminishes rapidly as we proceed to the westward. the surveys of pennsylvania and virginia show that the south-east was the quarter whence the coarser materials of these strata were derived, so that the ancient land lay in that direction. the conglomerate which forms the general base of the coal-measures is feet thick in the sharp mountain, where i saw it (at c) near pottsville; whereas it has only a thickness of feet, about thirty miles to the north-west, and dwindles gradually away when followed still farther in the same direction, till its thickness is reduced to feet.[ -a] the limestones, on the other hand, of the coal-measures, augment as we trace them westward. similar observations have been made in regard to the silurian and devonian formations in new york; the sandstones and all the mechanically-formed rocks thinning out as they go westward, and the limestones thickening, as it were, at their expense. it is, therefore, clear that the ancient land was to the east, where the atlantic now is; the deep sea, with its banks of coral and shells to the west, or where the hydrographical basin of the mississippi is now situated. in that region, near pottsville, where the thickness of the coal-measures is greatest, there are thirteen seams of anthracitic coal, several of them more than yards thick. some of the lowest of these alternate with beds of white grit and conglomerate of coarser grain than i ever saw elsewhere, associated with pure coal. the pebbles of quartz are often of the size of a hen's egg. on following these pudding-stones and grits for several miles from pottsville, by tamaqua, to the lehigh summit mine, in company with mr. h. d. rogers, in , he pointed out to me that the coarse-grained strata and their accompanying shales gradually thin out, until seven seams of coal, at first widely separated, are brought nearer and nearer together, until they successively unite; so that at last they form one mass, between and feet thick. i saw this enormous bed of anthracitic coal quarried in the open air at mauch chunk (or the bear mountain), the overlying sandstone, feet thick, having been removed bodily from the top of the hill, which, to use the miner's expression, had been "scalped." the accumulation of vegetable matter now constituting this vast bed of anthracite, may perhaps, before it was condensed by pressure and the discharge of its hydrogen, oxygen, and other volatile ingredients, have been between and feet thick. the origin of such a vast thickness of vegetable remains, so unmixed with earthy ingredients, can, i think, be accounted for in no other way, than by the growth, during thousands of years, of trees and ferns, in the manner of peat,--a theory which the presence of the stigmaria _in situ_ under each of the seven layers of anthracite, fully bears out. the rival hypothesis, of the drifting of plants into a sea or estuary, leaves the absence of sediment, or, in this case, of sand and pebbles, wholly unexplained. [illustration: fig. . cross section.] [illustration: fig. . cross section.] but the student will naturally ask, what can have caused so many seams of coal, after they had been persistent for miles, to come together and blend into one single seam, and that one equal in the aggregate to the thickness of the several separate seams? often had the same question been put by english miners before a satisfactory answer was given to it by the late mr. bowman. the following is his solution of the problem. let _a a'_, fig. ., be a mass of vegetable matter, capable, when condensed, of forming a -foot seam of coal. it rests on the underclay _b b'_, filled with roots of trees _in situ_, and it supports a growing forest (c d). suppose that part of the same forest d e had become submerged by the ground sinking down feet, so that the trees have been partly thrown down and partly remain erect in water, slowly decaying, their stumps and the lower parts of their trunks being enveloped in layers of sand and mud, which are gradually filling up the lake d f. when this lake or lagoon has at length been entirely silted up and converted into land, say, in the course of a century, the forest c d will extend once more continuously over the whole area c f, as in fig. ., and another mass of vegetable matter (_g g'_), forming feet more of coal, may accumulate from c to f. we then find in the region f, two seams of coal (_a'_ and _g'_) each feet thick, and separated by feet of sandstone and shale, with erect trees based upon the lower coal, while, between d and c, we find these two seams united into a -yard coal. it may be objected that the uninterrupted growth of plants during the interval of a century will have caused the vegetable matter in the region c d to be thicker than the two distinct seams _a'_ and _g'_ at f; and no doubt there would actually be a slight excess representing one generation of trees with the remains of other plants, forming half an inch or an inch of coal; but this would not prevent the miner from affirming that the seam _a g_, throughout the area c d, was equal to the two seams _a'_ and _g'_ at f. the reader has seen, by reference to the section (fig. . p. .), that the strata of the appalachian coal-field assume an horizontal position west of the mountains. in that less elevated country, the coal-measures are intersected by three great navigable rivers, and are capable of supplying for ages, to the inhabitants of a densely peopled region, an inexhaustible supply of fuel. these rivers are the monongahela, the alleghany, and the ohio, all of which lay open on their banks the level seams of coal. looking down the first of these at brownsville, we have a fine view of the main seam of bituminous coal feet thick, commonly called the pittsburg seam, breaking out in the steep cliff at the water's edge; and i made the accompanying sketch of its appearance from the bridge over the river (see fig. .). here the coal, feet thick, is covered by carbonaceous shale (_b_), and this again by micaceous sandstone (_c_). horizontal galleries may be driven everywhere at very slight expense, and so worked as to drain themselves, while the cars, laden with coal and attached to each other, glide down on a railway, so as to deliver their burden into barges moored to the river's bank. the same seam is seen at a distance, on the right bank (at _a_), and may be followed the whole way to pittsburg, fifty miles distant. as it is nearly horizontal, while the river descends it crops out at a continually increasing, but never at an inconvenient, height above the monongahela. below the great bed of coal at brownsville is a fire-clay inches thick, and below this, several beds of limestone, below which again are other coal seams. i have also shown in my sketch another layer of workable coal (at _d d_), which breaks out on the slope of the hills at a greater height. here almost every proprietor can open a coal-pit on his own land, and the stratification being very regular, he may calculate with precision the depth at which coal may be won. the appalachian coal-field, of which these strata form a part (from c to e, section, fig. ., p. .), is remarkable for its vast area; for, according to professor h. d. rogers, it stretches continuously from n.e. to s.w., for a distance of miles, its greatest width being about miles. on a moderate estimate, its superficial area amounts to , square miles. [illustration: fig. . view of the great coal seam on the monongahela at brownsville, pennsylvania, u. s. _a._ ten-foot seam of coal. _b._ black bituminous or carbonaceous shale, feet thick. _c._ micaceous sandstone. _d d._ upper seam of coal, feet thick.] this coal formation, before its original limits were reduced by denudation, must have measured miles in length, and in some places more than miles in breadth. by again referring to the section (fig. ., p. .), it will be seen that the strata of coal are horizontal to the westward of the mountains in the region d e, and become more and more inclined and folded as we proceed eastward. now it is invariably found, as professor h. d. rogers has shown by chemical analysis, that the coal is most bituminous towards its western limit, where it remains level and unbroken, and that it becomes progressively debituminized as we travel south-eastward towards the more bent and distorted rocks. thus, on the ohio, the proportion of hydrogen, oxygen, and other volatile matters, ranges from forty to fifty per cent. eastward of this line, on the monongahela, it still approaches forty per cent., where the strata begin to experience some gentle flexures. on entering the alleghany mountains, where the distinct anticlinal axes begin to show themselves, but before the dislocations are considerable, the volatile matter is generally in the proportion of eighteen or twenty per cent. at length, when we arrive at some insulated coal-fields ( ', fig. .) associated with the boldest flexures of the appalachian chain, where the strata have been actually turned over, as near pottsville, we find the coal to contain only from six to twelve per cent. of bitumen, thus becoming a genuine anthracite.[ -a] it appears from the researches of liebig and other eminent chemists, that when wood and vegetable matter are buried in the earth, exposed to moisture, and partially or entirely excluded from the air, they decompose slowly and evolve carbonic acid gas, thus parting with a portion of their original oxygen. by this means, they become gradually converted into lignite or wood-coal, which contains a larger proportion of hydrogen than wood does. a continuance of decomposition changes this lignite into common or bituminous coal, chiefly by the discharge of carburetted hydrogen, or the gas by which we illuminate our streets and houses. according to bischoff, the inflammable gases which are always escaping from mineral coal, and are so often the cause of fatal accidents in mines, always contain carbonic acid, carburetted hydrogen, nitrogen, and olefiant gas. the disengagement of all these gradually transforms ordinary or bituminous coal into anthracite, to which the various names of splint coal, glance coal, culm, and many others, have been given. we have seen that, in the appalachian coal-field, there is an intimate connection between the extent to which the coal has parted with its gaseous contents, and the amount of disturbance which the strata have undergone. the coincidence of these phenomena may be attributed partly to the greater facility afforded for the escape of volatile matter, where the fracturing of the rocks had produced an infinite number of cracks and crevices, and also to the heat of the gases and water penetrating these cracks, when the great movements took place, which have rent and folded the appalachian strata. it is well known that, at the present period, thermal waters and hot vapours burst out from the earth during earthquakes, and these would not fail to promote the disengagement of volatile matter from the carboniferous rocks. _continuity of seams of coal._--as single seams of coal are continuous over very wide areas, it has been asked, how forests could have prevailed uninterruptedly over such wide spaces, without being oftener flooded by turbid rivers, or, when submerged, denuded by marine currents. it appears, from the description of the cape breton coal-field, by mr. richard brown, that false stratification is common in the beds of sand, and some partial denudation of these, at least, must often have taken place during the accumulation of the carboniferous series. in the forest of dean, ancient river-channels are found, which pass through beds of coal, and in which rounded pebbles of coal occur. they are of older date than the overlying and undisturbed coal-measures. the late mr. buddle, who described them to me, told me he had seen similar phenomena in the newcastle coal-field. nevertheless, instances of these channels are much more rare than we might have anticipated, especially when we remember how often the roots of trees (_stigmariæ_) have been torn up, and drifted in broken fragments into the grits and sandstones. the prevalence of a downward movement is, no doubt, the principal cause which has saved so many extensive seams of coal from destruction by fluviatile action. the purity of the coal, or its non-intermixture with earthy matter, presents another theoretical difficulty to many geologists, who are inclined to believe that the trees and smaller plants of the carboniferous period grew in extensive swamps, rather than on land not liable to be inundated. it appears, however, that in the alluvial plain and delta of the mississippi, extensive "cypress swamps," as they are called, densely covered with various trees, occur, into which no matter held in mechanical suspension is ever introduced during the greatest inundations, inasmuch as they are all surrounded by a dense marginal belt of reeds, canes, and brushwood. through this thick barrier the river-water must pass, so that it is invariably well filtered before it can reach the interior of the forest-covered area, within which, vegetable matter is continually accumulating from the decay of trees and semi-aquatic plants. in proof of this, i may observe, that whenever any part of a swamp is dried up, during an unusually hot season, and the wood set on fire, pits are burnt into the ground many feet deep, or as far down as the fire can descend without meeting with water, and it is then found that scarcely any residuum or earthy matter is left.[ -a] at the bottom of these "cypress swamps" of the mississippi, a bed of clay is found, with roots of the tall cypress (_taxodium distichum_), just as the underclays of the coal are filled with _stigmaria_. _climate of coal period._--so long as the botanist taught that a tropical climate was implied by the carboniferous flora, geologists might well be at a loss to reconcile the preservation of so much vegetable matter with a high temperature; for heat hastens the decomposition of fallen leaves and trunks of trees, whether in the atmosphere or in water.[ -a] it is well known that peat, so abundant in the bogs of high latitudes, ceases to grow in the swamps of warmer regions. it seems, however, to have become a more and more received opinion, that the coal-plants do not, on the whole, indicate a climate resembling that now enjoyed in the equatorial zone. tree-ferns range as far south as the southern part of new zealand, and araucarian pines occur in norfolk island. a great predominance of ferns and lycopodiums indicates warmth, moisture, equability of temperature, and freedom from frost, rather than intense heat; and we know too little of the sigillariæ, calamites, asterophyllites, and other peculiar forms of the carboniferous period, to be able to speculate with confidence on the kind of climate they may have required. no doubt, we are entitled to presume, from the corals and cephalopoda of the mountain limestone, that a warm temperature characterized the northern seas in the carboniferous era; but the absence of cold may have given rise (as at present in the seas of the bermudas, under the influence of the gulf stream) to a very wide geographical range of stone-building corals and shell-bearing cuttle-fish, without its being necessary to call in the aid of tropical heat.[ -b] carboniferous reptiles. where we have evidence in a single coal-field, as in that of nova scotia, or south wales, of fifty or even a hundred ancient forests buried one above the other, with the roots of trees still in their original position, and with some of the trunks still remaining erect, we are apt to wonder that until the year no remains of contemporaneous air-breathing creatures, except a few insects, had been discovered. no vertebrated animals more highly organized than fish, no mammalia or birds, no saurians, frogs, tortoises, or snakes, were yet known in rocks of such high antiquity. in the coal-field of coalbrook dale mention had been made of two species of beetles of the family _curculionidæ_, and of a neuropterous insect resembling the genus _corydalis_, with another related to the _phasmidæ_.[ -c] in other coal-measures in europe we find notice of a scorpion and of a moth allied to _tinea_, also of one air-breathing crustacean, or land-crab. yet agassiz had already described in his great work on fossil fishes more than one hundred and fifty species of ichthyolites from the coal strata, ninety-four belonging to the families of shark and ray, and fifty-eight to the class of ganoids. some of these fish are very remote in their organization from any now living, especially those of the family called _sauroid_ by agassiz; as _megalichthys_, _holoptychius_, and others, which are often of great size, and all predaceous. their osteology, says m. agassiz, reminds us in many respects of the skeletons of saurian reptiles, both by the close sutures of the bones of the skull, their large conical teeth striated longitudinally (see fig. .), the articulations of the spinous processes with the vertebræ, and other characters. yet they do not form a family intermediate between fish and reptiles, but are true _fish_, though doubtless more highly organized than any living fish.[ -a] [illustration: fig. . _holoptychius hibberti_, ag. fifeshire coal-field; natural size.] the annexed figure represents a large tooth of the _megalichthys_, found by mr. horner in the cannel coal of fifeshire. it probably inhabited an estuary, like many of its contemporaries, and frequented both rivers and the sea. [illustration: fig. . _archegosaurus minor_, goldfuss. fossil reptile from the coal-measures, saarbrück.] at length, in , the first skeleton of a true reptile was announced from the coal of münster-appel in rhenish bavaria, by h. von meyer, under the name of _apateon pedestris_, the animal being supposed to be nearly related to the salamanders. three years later, in , prof. von dechen found in the coal-field of saarbrück, at the village of lebach, between strasburg and treves, the skeletons of no less than three distinct species of air-breathing reptiles, which were described by the late prof. goldfuss under the generic name of _archegosaurus_. the ichthyolites and plants found in the same strata, left no doubt that these remains belonged to the true coal period. the skulls, teeth, and the greater portions of the skeleton, nay, even a large part of the skin, of two of these reptiles have been faithfully preserved in the centre of spheroidal concretions of clay-iron-stone. the largest of these lizards, _archegosaurus decheni_, must have been feet inches long. the annexed drawing represents the smallest of the three of the natural size. they were considered by goldfuss as saurians, but by herman von meyer as most nearly allied to the _labyrinthodon_, and therefore connected with the batrachians, as well as the lizards. the remains of the extremities leave no doubt that they were quadrupeds, "provided," says von meyer, "with hands and feet terminating in distinct toes; but these limbs were weak, serving only for swimming or creeping." the same anatomist has pointed out certain points of analogy between their bones and those of the _proteus anguinus_; and mr. owen has observed to me that they make an approach to the _proteus_ in the shortness of their ribs. two of these ancient reptiles retain a large part of the outer skin, which consisted of long, narrow, wedge-shaped, tile-like, and horny scales, arranged in rows (see fig. .). [illustration: fig. . imbricated covering of skin of _archegosaurus medius_, goldf.; magnified.[ -a]] _cheirotherian footprints in coal measures, united states._--in , the very year when the apateon or salamander of the coal was first met with in the country between the moselle and the rhine, dr. king published an account of the footprints of a large reptile discovered by him in north america. these occur in the coal strata of greensburg, in westmoreland county, pennsylvania; and i had an opportunity of examining them in . i was at once convinced of their genuineness, and declared my conviction on that point, on which doubts had been entertained both in europe and the united states. the footmarks were first observed standing out in relief from the lower surface of slabs of sandstone, resting on thin layers of fine unctuous clay. i brought away one of these masses, which is represented in the accompanying drawing (fig. .). it displays, together with footprints, the casts of cracks (_a_, _a'_) of various sizes. the origin of such cracks in clay, and casts of the same, has before been explained, and referred to the drying and shrinking of mud, and the subsequent pouring of sand into open crevices. it will be seen that some of the cracks, as at _b_, _c_, traverse the footprints, and produce distortion in them, as might have been expected, for the mud must have been soft when the animal walked over it and left the impressions; whereas, when it afterwards dried up and shrank, it would be too hard to receive such indentations. no less than twenty-three footsteps were observed by dr. king in the same quarry before it was abandoned, the greater part of them so arranged (see fig. .) on the surface of one stratum as to imply that they were made successively by the same animal. everywhere there was a double row of tracks, and in each row they occur in pairs, each pair consisting of a hind and fore foot, and each being at nearly equal distances from the next pair. in each parallel row the toes turn the one set to the right, the other to the left. in the european _cheirotherium_, before mentioned (p. .), both the hind and fore feet have each five toes, and the size of the hind foot is about five times as large as the fore foot. in the american fossil the posterior footprint is not even twice as large as the anterior, and the number of toes is unequal, being five in the hinder and four in the anterior foot. in this, as in the european _cheirotherium_, one toe stands out like a thumb, and these thumb-like toes turn the one set to the right, and the other to the left. the american _cheirotherium_ was evidently a broader animal, and belonged to a distinct genus from that of the triassic age in europe.[ -a] [illustration: fig. . _scale one-sixth the original._ slab of sandstone from the coal-measures of pennsylvania, with footprints of air-breathing reptile and casts of cracks.] we may assume that the reptile which left these prints on the ancient sands of the coal-measures was an air-breather, because its weight would not have been sufficient under water to have made impressions so deep and distinct. the same conclusion is also borne out by the casts of the cracks above described, for they show that the clay had been exposed to the air and sun, so as to have dried and shrunk. [illustration: fig. . series of reptilian footprints in the coal-strata of westmoreland county, pennsylvania. _a._ mark of nail?] the geological position of the sandstone of greensburg is perfectly clear, being situated in the midst of the appalachian coal-field, having the main bed of coal, called the pittsburg seam, above mentioned (p. .), yards thick, feet above it, and worked in the neighbourhood, with several other seams of coal at lower levels. the impressions of _lepidodendron_, _sigillaria_, _stigmaria_, and other characteristic carboniferous plants, are found both above and below the level of the reptilian footsteps. analogous footprints of a large reptile of still older date have since been found ( ), by mr. isaac lea, in the lowest beds of the coal formation at pottsville, near philadelphia, so that we may now be said to have the footmarks of two reptilians of the coal period, and the skeletons of four.[ -a] carboniferous or mountain limestone. we have already seen that this rock lies sometimes entirely beneath the coal-measures, while, in other districts, it alternates with the shales and sandstone of the coal. in both cases it is destitute of land plants, and usually charged with corals, which are often of large size; and several species belong to the lamelliferous class of lamarck, which enter largely into the structure of coral reefs now growing. there are also a great number of _crinoidea_ (see fig. .), and a few _echinoderms_, associated with the zoophytes above mentioned. the _brachiopoda_ constitute a large proportion of the mollusca, many species being referable to two extinct genera, _spirifer_ (or _spirifera_) (fig. .), and _productus_ (_leptæna_) (fig. .). [illustration: fig. . _cyathocrinites planus_, miller. mountain limestone.] [illustration: fig. . _spirifer glaber_, sow. mountain limestone.] [illustration: fig. . _productus martini_, sow. (_p. semireticulatus_, flem.) mountain limestone.] among the spiral univalve shells the extinct genus _euomphalus_ (see fig. .) is one of the commonest fossils of the mountain limestone. in the interior it is often divided into chambers (see fig. . _d_); the septa or partitions not being perforated, as in foraminiferous shells, or in those having siphuncles, like the nautilus. the animal appears, like the recent _bulimus decollatus_, to have retreated at different periods of its growth, from the internal cavity previously formed, and to have closed all communication with it by a septum. the number of chambers is irregular, and they are generally wanting in the innermost whorl. [illustration: fig. . _euomphalus pentagulatus_, min. con. mountain limestone. _a._ upper side; _b._ lower, or umbilical side; _c._ view showing mouth which is less pentagonal in older individuals; _d._ view of polished section, showing internal chambers.] [illustration: fig. . portion of _orthoceras laterale_, phillips. mountain limestone.] there are also many univalve and bivalve shells of existing genera in the mountain limestone, such as _turritella_, _buccinum_, _patella_, _isocardia_, _nucula_, and _pecten_.[ -a] but the _cephalopoda_ depart, in general, more widely from living forms, some being generically distinct from all those found in strata newer than the coal. in this number may be mentioned _orthoceras_, a siphuncled and chambered shell, like a _nautilus_ uncoiled and straightened. some species of this genus are several feet long (fig. .). the _goniatite_ is another genus, nearly allied to the _ammonite_, from which it differs in having the lobes of the septa free from lateral denticulations, or crenatures; so that the outline of these is continuous and uninterrupted (see _a_, fig. .). their siphon is small, and in the form of the striæ of growth they resemble _nautili_. another extinct generic form of cephalopod, abounding in the mountain limestone, and not found in strata of later date, is the _bellerophon_ (fig. .), of which the shell, like the living argonaut, was without chambers. [illustration: fig. . _goniatites evolutus_, phillips.[ -a] mountain limestone.] [illustration: fig. . _bellerophon costatus_, sow.[ -b] mountain limestone.] footnotes: [ -a] h. d. rogers, trans. assoc. amer. geol., - , p. . [ -a] trans. of ass. of amer. geol., p. . [ -a] lyell's second visit to the u. s., vol. ii. p. . american journ. of sci., d series, vol. v. p. . [ -a] principles of geol., p. . [ -b] for changes in climate, see principles of geol., chaps. vii. and viii. [ -c] geol. trans., d series, vol. vi. p. . [ -a] agassiz, poiss. foss., lib. . p. . and liv. . p. . [ -a] goldfuss, neue jenaische lit. zeit., ; and von meyer, quart. geol. journ., vol. iv. p. ., memoirs. [ -a] see lyell's second visit, &c., vol. ii. p. . [ -a] these impressions, found by mr. lea, were imagined to be in a rock as ancient as the old red sandstone; but, according to mr. h. d. rogers, they are in the lowest part of the coal formation. [ -a] phillips, geol. of yorksh., vol. ii. p. . [ -a] phillips, geol. of yorksh., pl. . fig. . [ -b] ibid., pl. . fig. . chapter xxvi. old red sandstone, or devonian group. old red sandstone of scotland, and borders of wales--fossils usually rare--"old red" in forfarshire--ichthyolites of caithness--distinct lithological type of old red in devon and cornwall--term "devonian"--organic remains of intermediate character between those of the carboniferous and silurian systems--corals and shells--devonian strata of westphalia, the eifel, russia, and the united states--coral reef at falls of the ohio--devonian flora. it was stated in chap. xxii. that the carboniferous formation is surmounted by one called the "new red," and underlaid by another called the "old red sandstone."[ -c] the british strata of the last mentioned series were first recognized in herefordshire and scotland as of great thickness, and immediately subjacent to the coal; but they were in general so barren of organic remains, that it was difficult to find paleontological characters of sufficient importance to distinguish them as an independent group. in scotland, and on the borders of wales, the "old red" consists chiefly of red sandstone, conglomerate, and shale, with few fossils; but limestones of the same age, peculiarly rich in organic remains, were at length found in devonshire. i shall first advert to the characters of the group as developed in herefordshire, worcestershire, shropshire, and south wales. its thickness has been estimated at feet, and it has been subdivided into-- st. a quartzose conglomerate passing downwards into chocolate-red and green sandstone and marl. d. cornstone and marl--red and green argillaceous spotted marls, with irregular courses of impure concretionary limestone, provincially called cornstone. here, as usual, fossils are extremely rare in the clays and sandstones in which the red oxide of iron prevails; but remains of fishes of the genera _cephalaspis_ and _onchus_ have been discovered in the cornstone. the whole of the northern part of scotland, from cape wrath to the southern flank of the grampians, has been well described by mr. miller as consisting of a nucleus of granite, gneiss, and other hypogene rocks, which seem as if set in a sandstone frame.[ -a] the beds of the old red sandstone constituting this frame, may once perhaps have extended continuously over the entire grampians before the upheaval of that mountain range; for one band of the sandstone follows the course of the moray frith far into the interior of the great caledonian valley; and detached hills and island-like patches occur in several parts of the interior, capping some of the higher summits in sutherlandshire, and appearing in morayshire like oases among the granite rocks of strathspey. on the western coast of ross-shire, the old red forms those three immense insulated hills before described (p. .), where beds of horizontal sandstone, feet high, rest unconformably on a base of gneiss, attesting the vast denudation which has taken place. but in order to observe the uppermost part of the old red, we must travel south of the grampians, and examine its junction with the bottom of the carboniferous series in fifeshire. this upper member may be seen in dura den, south of cupar, to consist of a belt of yellow sandstone, in which dr. fleming first discovered scales of _holoptychius_, and in which species of fish of the genera _pterichthys_, _pamphractus_, and others, have been met with. (for genus _pterichthys_, see fig. . p. .) the beds next below the yellow sandstone are well seen in the large zone of old red which skirts the southern flank of the grampians from stonehaven to the frith of clyde. it there forms, together with trap, the sidlaw hills and the strata of the valley of strathmore. a section of this region has been already given (p. .), extending from the foot of the grampians in forfarshire to the sea at arbroath, a distance of about miles, where the entire series of strata is several thousand feet thick, and may be divided into three principal masses: st, and uppermost, red and mottled marls, cornstone, and sandstone (nos. . and . of the section); d, conglomerate, often of vast thickness (no. . ibid.); d, roofing and paving stone, highly micaceous, and containing a slight admixture of carbonate of lime (no. . ibid.). in the first of these divisions, which may be considered as succeeding the yellow sandstone of fifeshire before mentioned, a gigantic species of fish of the genus _holoptychius_ has been found at clashbinnie near perth. some scales (see fig. .) have been seen which measured inches in length by - / in breadth. at the top of the next division, or immediately under the conglomerate (no. . p. .), there have been found in forfarshire some remarkable crustaceans, with several fish of the genus named by agassiz _cephalaspis_, or "buckler-headed," from the extraordinary shield which covers the head (see fig. .), and which has often been mistaken for that of a trilobite, of the division _asaphus_. [illustration: fig. . scale of _holoptychius nobilissimus_, agas. clashbinnie. nat. size.] species of the same genus are considered in england as characteristic of the second or cornstone division (p. .). [illustration: fig. . _cephalaspis lyellii_, agass. length - / inches. from a specimen in my collection found at glammiss, in forfarshire. see other figures, agassiz, vol. ii. tab. . _a_. and . _b_. _a._ one of the peculiar scales with which the head is covered when perfect. these scales are generally removed, as in the specimen above figured. _b, c._ scales from different parts of the body and tail.] [illustration: fig. . _eggs of gasteropodous mollusk?_ lower beds of old red, ley's mill, forfarshire.] [illustration: fig. . _fucoids and eggs of gasteropodous mollusk?_ lower old red, fife.] in the same grey paving-stones and coarse roofing-slates, in which the _cephalaspis_ occurs, in forfarshire and kincardineshire, the remains of marine plants or fucoids abound. they are frequently accompanied by groups of hexagonal, or nearly hexagonal markings, which consist of small flattened carbonaceous bodies, placed in a slight depression of the sandstone or shale. (see figs. and .) they much resemble in form the spawn of the recent natica (see fig. .), in which the eggs are arranged in a thin layer of sand, and seem to have acquired a polygonal form by pressing against each other. the substance of the egg, if fossilized, might give rise to small pellicles of carbonaceous matter. [illustration: fig. . fragment of spawn of british species of _natica_.] these fossils i have met with, both to the north of strathmore, in the vertical shale beneath the conglomerate, and in the same beds in the sidlaw hills, at all the points where fig. . is introduced in the section, p. . [illustration: fig. . _pterichthys_, agassiz; upper side, showing mouth; as restored by h. miller.[ -a]] beds of red shale and red sandstone, sometimes associated with pudding-stone (older than no. ., fig. . p. .), and destitute of organic remains, separate, in the region of strathmore, the above-described fossiliferous strata from the older crystalline rocks of the grampians. but, in the north of scotland, we find, at the base of the old red, other grey slaty sandstones, in the counties of banff, nairn, moray, cromarty, caithness, and in orkney, rich in ichthyolites of peculiar forms, belonging to the genera _pterichthys_ (fig. .), _coccosteus_, _diplopterus_, _dipterus_, _cheiracanthus_, and others of agassiz. five species of _pterichthys_ have been found in this lowest division of the old red. the wing-like appendages, whence the genus is named, were first supposed by mr. miller to be paddles, like those of the turtle; but agassiz regards them as weapons of defence, like the occipital spines of the river bull-head (_cottus gobio_, linn.); and considers the tail to have been the only organ of motion. the genera _dipterus_ and _diplopterus_ are so named, because their two dorsal fins are so placed as to front the anal and ventral fins, so as to appear like two pairs of wings. they have bony enamelled scales. _south devon and cornwall._--a great step was made in the classification of the slaty and calciferous strata of south devon and cornwall in , when a large portion of the beds, previously referred to the "transition" or most ancient fossiliferous series, were found to belong in reality to the period of the old red sandstone. for this reform we are indebted to the labours of professor sedgwick and sir r. murchison, assisted by a suggestion of mr. lonsdale, who, in , after examining the south devonshire fossils, perceived that some of them agreed with those of the carboniferous group, others with those of the silurian, while many could not be assigned to either system, the whole taken together exhibiting a peculiar and intermediate character. but these paleontological observations alone would not have enabled us to assign, with accuracy, the true place in the geological series of these slate-rocks and limestones of south devon, had not messrs. sedgwick and murchison, in and , discovered that the culmiferous or anthracitic shales of north devon belonged to the coal, and not, as preceding observers had imagined, to the transition period. as the strata of south devon here alluded to are far richer in organic remains than the red sandstones of contemporaneous date in herefordshire and scotland, the new name of the "devonian system" was proposed as a substitute for that of old red sandstone. the rocks of this group in south devon consist, in great part, of green chloritic slates, alternating with hard quartzose slates and sandstones. here and there calcareous slates are interstratified with blue crystalline limestone, and in some divisions conglomerates, passing into red sandstone. the link supplied by the whole assemblage of imbedded fossils, connecting as it does the paleontology of the silurian and carboniferous groups, is one of the highest interest, and equally striking, whether we regard the _genera_ of corals or of shells. the _species_ are almost all distinct. among the more abundant corals, we find the genera _favosites_ and _cyathophyllum_, common on the one hand to the mountain limestone, and on the other to the silurian system. some few even of the _species_ are common to the devonian and silurian groups, as, for example, _favosites polymorpha_ (fig. .), very abundant in south devon. [illustration: fig. . _favosites polymorpha_, goldf., s. devon. from a polished specimen. _a._ portion of the same, magnified to show the pores.] the _cyathophyllum cæspitosum_ (fig. .) and _porites pyriformis_ (fig. . p. .) are more peculiarly characteristic of the devonian rocks. in regard to the shells, all the brachiopodous genera, such as _terebratula_, _orthis_, _spirifer_, _atrypa_, and _productus_, which are found in the mountain limestone, occur, together with those of the silurian system, except the _pentamerus_. some forms, however, seem exclusively devonian, as for example, _calceola sandalina_ (fig. .) and _strygocephalus burtini_ (fig. .), which have been met with both in the eifel, in germany, and in devonshire, in the very lowest devonian beds. [illustration: fig. . cyathophyllum. _a._ _cyathophyllum cæspitosum_, goldf., plymouth. _b._ a terminal star. _c._ vertical section exhibiting transverse plates, and part of another branch.] among the peculiar lamellibranchiate bivalves, also common to devonshire and the eifel, we find _megalodon cucullatus_ (fig. .). several spiral univalves are abundant, among which are many species of _pleurotomaria_ and _euomphalus_. among the cephalopoda we find _bellerophon_ and _orthoceras_, as in the silurian and carboniferous groups, and _goniatite_ and _cyrtoceras_, as in the carboniferous. in some of the upper devonian beds, a shell, resembling a flattened _goniatite_, occurs, called _clymenia_, by munster (_endosiphonites_, ansted.[ -a]). [illustration: fig. . _calceola sandalina_, lam. eifel; also south devon. _a._ both valves united. _b._ inner side of opercular valve.] [illustration: fig. . _strygocephalus burtini_. (_terebratula porrecta_, sow.) eifel; also south devon. _a._ valves united. _b_. side view of same. _c._ interior of larger valve, showing thick partition, and thinner one continued from it.] [illustration: fig. . _megalodon cucullatus_, sow. eifel; also bradley, s. devon. _a._ the valves united. _b._ interior of valve, showing the large cardinal tooth.] [illustration: fig. . _clymenia linearis_, munster. (_endosiphonites carinatus_, ansted.) cornwall.] a peculiar species of trilobite, called _brontes flabellifer_ (fig. .), is found in the devonian strata of the eifel and in south devon. it should be observed, however, that the head in the specimen here figured by goldfuss, the most perfect which could be obtained, is incomplete, and a restoration has been attempted by mr. salter in fig. ., from data supplied by other species of the same genus occurring in older rocks. [illustration: fig. . _brontes flabellifer_, goldf. eifel; also s. devon.] [illustration: fig. . restored outline of head of _brontes flabellifer_.] for determining the true equivalents of the devonian group in the rhenish provinces and adjacent parts of germany, we are indebted to the labours of messrs. sedgwick and murchison, in , from which it appears that rocks of that age emerge from beneath the coal-field of westphalia, and are also found in troughs among the silurian rocks in nassau. many of the limestones, particularly those on the river lahn, are identical, both in structure and in coralline remains, with the beautiful marbles of babbacombe, torquay, and plymouth. the limestones of the eifel, long ago celebrated for their fossils, and which lie in a basin supported by silurian rocks, are found to be referable to the lower part of the devonian system. in russia, also, messrs. murchison and de verneuil have shown ( ) that the "old red" group occupies a wide area south from st. petersburg. it was formerly supposed to be the new red sandstone, on account of its saliferous and gypseous beds; but it is now proved to be the old red by containing ichthyolites of genera which characterize this group in the british isles, as, for example, _holoptychius_, _coccosteus_, _diplopterus_, &c.[ -a], associated with mollusca found in the devonian of western europe. among the fish are also many species of sharks of the cestraciont division, a fact worthy of notice, because the squaloid fishes of the present day offer the highest organization of the brain and of the generative organs, and make, in these respects, the nearest approach to the higher vertebrate classes. _devonian strata in the united states._ the position of this formation between the carboniferous rocks of pennsylvania and ohio, is pointed out in the section, fig. . p. ., and it is a remark of m. de verneuil that in no european country is there so complete and uninterrupted a development of the devonian system as in north america. at the falls of the ohio, at louisville, in kentucky, there is a grand display of one of the limestones of this period, resembling a modern coral reef. a wide extent of surface is exposed in a series of horizontal ledges, at all seasons, when the water is not high; and the softer parts of the stone having decomposed and wasted away, the harder calcareous corals stand out in relief, and many of them send out branches from their erect stems precisely as if they were living. among other species i observed large masses, not less than feet in diameter, of _favosites gothlandica_, with its beautiful honeycomb structure well displayed, and, by the side of it, the _favistella_, combining a similar honeycombed form with the star of the _astrea_. there was also the cup-shaped _cyathophyllum_, and the delicate network of the _fenestella_, and that elegant and well-known european species of fossil, called "the chain coral," _catenipora escharoides_, with a profusion of others (see fig. . p. .). these coralline forms were mingled with the joints, stems, and occasionally the heads, of lily encrinites. although hundreds of fine specimens have been detached from these rocks, to enrich the museums of europe and america, another crop is constantly working its way out, under the action of the stream, and of the sun and rain, in the warm season when the channel is laid dry. the waters of the ohio, when i visited the spot in april, , were more than feet below their highest level, and feet above their lowest, so that large spaces of bare rock were exposed to view.[ -b] _devonian flora._ with the exception of the fucoids above mentioned (p. .), but little is known with certainty of the plants of the devonian group. those found in the department of la sarthe in france, and in various parts of brittany, formerly referred to the devonian era, have been shown (in ), by m. de verneuil, to belong to the carboniferous series. the same may be said of the species of _lepidodendron_, _knorria_, _calamite_, _sagenaria_, and other genera recently figured ( ), by mr. f. a. römer, from the formation called "greywacké à posodonomyes" in the hartz.[ -a] they are accompanied by _goniatites reticulatus_ phillips, _g. intercostatus_ phil., and other mountain limestone species, and had been previously assigned to the oldest part of the carboniferous series by messrs. murchison and sedgwick. if hereafter we should become well acquainted with the land plants of the devonian era, we may confidently expect that nearly all of them will agree generically with those of the carboniferous period, but the species will be as different as are the devonian vertebrate and invertebrate animals from the fossil species of the coal. footnotes: [ -c] see section, fig. . p. . [ -a] the old red sandstone, by hugh miller, . [ -a] old red sandstone. plate . fig. . mr. m.'s description of the fish is most graphic and correct. [ -a] camb. phil. trans., vol. vi. pl. . fig. . [ -a] see proceedings of geol. soc., and the anniversary speech of dr. buckland, p. g. s., for . [ -b] lyell's second visit to the united states, vol. ii. p. . [ -a] memoir on the hartz, palæontographica of dunker and von meyer, part iii. chapter xxvii. silurian group. silurian strata formerly called transition--term grauwacké--subdivisions of upper and lower silurian--ludlow formation and fossils--wenlock formation, corals and shells--caradoc and llandeilo beds--graptolites--lingula--trilobites--cystideæ--vast thickness of silurian strata in north wales--unconformability of caradoc sandstone--silurian strata of the united states--amount of specific agreement of fossils with those of europe--great number of brachiopods--deep-sea origin of silurian strata--absence of fluviatile formations--mineral character of the most ancient fossiliferous rocks. we come next in the descending order to the most ancient of the primary fossiliferous rocks, that series which comprises the greater part of the strata formerly called "transition" by werner, for reasons explained in chap. viii., pp. and . geologists have also applied to these older strata the general name of "grauwacké," by which the german miners designate a particular variety of sandstone, usually an aggregate of small fragments of quartz, flinty slate (or lydian stone), and clay-slate cemented together by argillaceous matter. far too much importance has been attached to this kind of rock, as if it belonged to a certain epoch in the earth's history, whereas a similar sandstone or grit is found sometimes in the old red, and in the millstone grit of the coal, and sometimes in certain cretaceous and even eocene formations in the alps. the name of _silurian_ was first proposed by sir roderick murchison, for a series of fossiliferous strata lying below the old red sandstone, and occupying that part of wales and some contiguous counties of england, which once constituted the kingdom of the _silures_, a tribe of ancient britons. the strata have been divided into upper and lower silurian, and these again in the region alluded to admit of several well-marked subdivisions, all of them explained in the following table. upper silurian rocks. prevailing thickness organic lithological in feet. remains. characters. { {finely laminated } } {tilestones. { reddish and } ? } { { green sandstones } } { { and shales. } } . ludlow { }marine mollusca of formation {upper {micaceous grey } } almost every order, {ludlow. { sandstone. } } the brachiopoda most { } } abundant. serpula, {aymestry {argillaceous } } corals, sauroid fish, {limestone. { limestone. } } fuci. { } } {lower {shale, with } } {ludlow. { concretions of } } { { limestone. } } {wenlock }concretionary } {marine mollusca of {limestone. } limestone. } { various orders as . wenlock { } } { before, crustaceans formation. { } } { of the trilobite { } } { family. {wenlock }argillaceous } {oldest bones of {shale. } shale. } { fish yet known. lower silurian rocks. {flags of shelly } { { limestone and } {crinoidea, corals, . caradoc {caradoc { sandstone, thick } { mollusca, chiefly formation. {sandstones. { bedded white } { brachiopoda, { freestone. } { trilobites. . llandeilo {llandeilo }dark coloured } {mollusca, formation. {flags. } calcareous flags. } { trilobites. upper silurian rocks. _ludlow formation._--this member of the upper silurian group, as will be seen by the above table, is of great thickness, and subdivided into four parts,--the tilestone, the upper and lower ludlow, and the intervening aymestry limestone. each of these may be distinguished near the town of ludlow, and at other places in shropshire and herefordshire, by peculiar organic remains. . _tilestones._--this uppermost division was originally classed by sir r. murchison with the old red sandstone, because they decompose into a red soil throughout the silurian region. at the same time he regarded the tilestones as a transition group forming a passage from silurian to old red. it is now ascertained that the fossils agree in great part specifically, and in general character entirely, with those of the succeeding formation. . _upper ludlow._--the next division, called the upper ludlow, consists of grey calcareous sandstone, decomposing into soft mud, and contains, among other shells, the _lingula cornea_, which is common to it and the lowest, or tilestone beds of the old red. but the _orthis orbicularis_ is peculiar to the upper ludlow, and very common; and the lowest or mudstone beds, are loaded for a thickness of feet with _terebratula navicula_ (fig. .), in vast numbers. among the cephalopodous mollusca occur the genera _bellerophon_ and _orthoceras_, and among the crustacea the _homalonotus_ (fig. . p. .). a coral called _favosites polymorpha_, goldf. (fig. . p. .) is found both in this subdivision and in the devonian system. [illustration: fig. . _orthis orbicularis_, j. sow. delbury. upper ludlow.] [illustration: fig. . _terebratula navicula_, j. sow. aymestry limestone; also in upper and lower ludlow.] among the fossil shells are species of _leptæna_, _orthis_, _terebratula_, _avicula_, _trochus_, _orthoceras_, _bellerophon_, and others.[ -a] some of the upper ludlow sandstones are ripple-marked, thus affording evidence of gradual deposition; and the same may be said of the accompanying fine argillaceous shales which are of great thickness, and have been provincially named "mudstones." in these shales many zoophytes are found enveloped in an erect position, having evidently become fossil on the spots where they grew at the bottom of the sea. the facility with which these rocks, when exposed to the weather, are resolved into mud, proves that, notwithstanding their antiquity, they are nearly in the state in which they were first thrown down. the scales, spines (_ichthyodorulites_), jaws, and teeth of fish of the genera _onchus_, _plectrodus_, and others of the same family, have been met with in the upper ludlow rocks. [illustration: fig. . _pentamerus knightii_, sow. aymestry. _a._ view of both valves united. _b._ longitudinal section through both valves, showing the central plate or septum; half nat. size.] . _aymestry limestone._--the next group is a subcrystalline and argillaceous limestone, which is in some places feet thick, and distinguished around aymestry by the abundance of _pentamerus knightii_, sow. (fig. .), also found in the lower ludlow. this genus of brachiopoda has only been found in the silurian strata. the name was derived from +pente+, _pente_, five, and +meros+, _meros_, a part, because both valves are divided by a central septum, making four chambers, and in one valve the septum itself contains a small chamber, making five; but neither the structure of this shell, nor the connection of the animal with its several parts, are as yet understood. messrs. murchison and de verneuil discovered this species dispersed in myriads through a white limestone of upper silurian age, on the banks of the is, on the eastern flank of the urals in russia. [illustration: fig. . _lingula lewisii_, j. sow. abberley hills.] three other abundant shells in the aymestry limestone are, st, _lingula lewisii_ (fig. .); d, _terebratula wilsoni_, sow. (fig. .), which is also common to the lower ludlow and wenlock limestone; d, _atrypa reticularis_, lin. (fig. .), which has a very wide range, being found in every part of the silurian system, except the llandeilo flags. [illustration: fig. . _terebratula wilsoni_, sow. aymestry.] [illustration: fig. . _atrypa reticularis._ linn. syn. _terebratula affinis_, min. con. aymestry. _a._ upper valve. _b._ lower. _c._ anterior margin of the valves.] . _lower ludlow shale._--a dark grey argillaceous deposit, containing, among other fossils, the new genera of chambered shells, the _phragmoceras_ of broderip, and the _lituites_ of breyn (see figs. , .). the latter is partly straight and partly convoluted, nearly as in _spirula_. [illustration: fig. . _phragmoceras ventricosum_, j. sow. (_orthoceras ventricosum_, stein.) aymestry; / nat. size.] [illustration: fig. . _lituites giganteus_, j. sow. near ludlow; also in the aymestry and wenlock limestones; / nat. size.] [illustration: fig. . fragments of orthoceras. _a._ fragment of _orthoceras ludense_, j. sow. _b._ polished section, showing siphuncle. ludlow.] the _orthoceras ludense_ (fig. .), as well as the shell last mentioned, is peculiar to this member of the series. the _homalonotus delphinocephalus_ (fig. .) is common to this division and to the wenlock limestone. this crustacean belongs to a group of trilobites which has been met with in the silurian rocks only, and in which the tripartite character of the dorsal crust is almost lost. [illustration: fig. . _homalonotus delphinocephalus_, könig.[ -a] dudley castle; / nat. size.] a species of graptolite, _g. ludensis_, murch. (fig. .), a form of zoophyte which has not yet been met with in strata newer than the silurian, occurs in the lower ludlow. _wenlock formation._--we next come to the wenlock formation, which has been divided (see table, p. .) into . wenlock limestone, formerly well known to collectors by the name of the dudley limestone, which forms a continuous ridge, ranging for about miles from s.w. to n.e., about a mile distant from the nearly parallel escarpment of the aymestry limestone. the prominence of this rock in shropshire, like that of aymestry, is due to its solidity, and to the softness of the shales above and below. it is divided into large concretional masses of pure limestone, and abounds in trilobites, among which the prevailing species are _phacops caudatus_ (fig. .) and _calymene blumenbachii_, commonly called the dudley trilobite. the latter is often found coiled up like a wood-louse (see fig. .). [illustration: fig. . _graptolithus ludensis_, murchison. lower ludlow.] [illustration: fig. . _calymene blumenbachii_, brong. wenlock, l. ludlow, and aym. limest.] [illustration: fig. . _leptæna depressa._ wenlock.] [illustration: fig. . _phacops caudatus_, brong. wenlock, aym. limest., and l. ludlow.] _leptæna depressa_, sow., is common in this rock, but also ranges through the lower ludlow, wenlock shale, and caradoc sandstone. [illustration: fig. . _catenipora escharoides._] among the corals in which this formation is very rich, the _catenipora escharoides_, lam. (fig. .), or chain coral, may be pointed out as one very easily recognized, and widely spread in europe, ranging through all parts of the silurian group, from the aymestry limestone to the bottom of the series. another coral, the _porites pyriformis_, is also met with in profusion; a species common to the devonian rocks. _cystiphyllum siluriense_ (fig. .) is a species peculiar to the wenlock limestone. this new genus, the name of which is derived from +kystis+, a _bladder_, and +phyllon+, a _leaf_, was instituted by mr. lonsdale for corals of the silurian and devonian groups. it is composed of small bladder-like cells (see fig. . _b._). . the wenlock shale, which exceeds feet in thickness, contains many species of brachiopoda, such as a small variety of the _lingula lewisii_ (fig. .), and the _atrypa reticularis_ (fig. .) before mentioned, and it will be seen that several other fossils before enumerated range into this shale. [illustration: fig. . _porites pyriformis_, ehren. wenlock limest. and shale. also in aymestry limestone, and l. ludlow. _a._ vertical section, showing transverse lamellæ.] [illustration: fig. . cystiphyllum. _a._ _cystiphyllum siluriense_, lonsd. wenlock. _b._ section of portion, showing cells.] lower silurian rocks. the lower silurian rocks have been subdivided into two portions. . the caradoc sandstone, which abuts against the trappean chain called the caradoc hills, in shropshire. its thickness is estimated at feet, and the larger proportion of its fossils are specifically distinct from those of the upper silurian rocks. among them we find many trilobites and shells of the genera _orthoceras_, _nautilus_, and _bellerophon_; and among the brachiopoda the _pentamerus oblongus_ and _p. lævis_ (fig. .), which are very abundant and peculiar to this bed; also _orthis grandis_ (fig. .), and a fossil of well-defined form, _tentaculites annulatus_, schlot. (fig. .), which mr. salter has shown to be referable to the annelids and to the same tribe as _serpula_. [illustration: fig. . _pentamerus lævis_, sow. caradoc sandstone. perhaps the young of _pentamerus oblongus_. _a, b._ views of the shell itself, from figures in murchison's sil. syst. _c._ cast with portion of shell remaining, and with the hollow of the central septum filled with spar. _d._ internal cast of a valve, the space once occupied by the septum being represented by a hollow in which is seen a cast of the chamber within the septum.] [illustration: fig. . cast of _orthis grandis_, j. sow. horderley; two-thirds of nat. size.] [illustration: fig. . _tentaculites scalaris_, schlot. eastnor park; nat. size, and magnified.] the most ancient bony remains of fish yet discovered in great britain are those obtained from the wenlock limestones; but coprolites referred to fish occur still lower in the silurian series in wales. [illustration: fig. . _ogygia buchii_, burmeister. syn. _asaphus buchii_, brong. / nat. size. radnorshire.] . the _llandeilo flags_, so named from a town in caermarthenshire, form the base of the silurian system, consisting of dark-coloured micaceous grit, frequently calcareous, and distinguished by containing the large trilobites _asaphus buchii_ and _a. tyrannus_, murch., both of which are peculiar to these rocks. several species of graptolites (fig. .) occur in these beds. [illustration: fig. . _a_, _b_. _graptolithus murchisonii_, beck. llandeilo flags.] [illustration: fig. . _g. foliaceus_, _murchison_. llandeilo flags.] in the fine shales of this formation graptolites are very abundant. i collected these same bodies in great numbers in sweden and norway in - , both in the higher and lower shales of the silurian system; and was informed by dr. beck of copenhagen, that they were fossil zoophytes related to the genera _pennatula_ and _virgularia_, of which the living species now inhabit mud and slimy sediment. the most eminent naturalists still hold to this opinion. a species of _lingula_ is met with in the lowest part of the llandeilo beds; and it is remarkable that this brachiopod is among the earliest, if not the most ancient animal form detected in the lowest silurian of north america. these inhabitants of the seas, of so remote an epoch, belonged so strictly to the living genus _lingula_, as to demonstrate, like the pteriform ferns of the coal, through what incalculable periods of time the same plan and type of organization has sometimes prevailed. among the forms of trilobite extremely characteristic of the lower silurian throughout europe and north america, the _trinucleus_ may be mentioned. this family of crustaceans appears to have swarmed in the silurian seas, just as crabs, shrimps, and other genera of crustaceans abound in our own. burmeister, in his work on the organization of trilobites, supposes them to have swum at the surface of the water in the open sea and near coasts, feeding on smaller marine animals, and to have had the power of rolling themselves into a ball as a defence against injury. they underwent various transformations analogous to those of living crustaceans. m. barrande, author of a work on the silurian rocks of bohemia, has traced the same species from the young state just after its escape from the egg to the adult form, through various metamorphoses, each having the appearance of a distinct species. yet, notwithstanding the numerous species of preceding naturalists which he has thus succeeded in uniting into one, he announces a forthcoming work in which descriptions and figures of species of trilobite will be given. [illustration: fig. . _trinucleus ornatus_, burm.] _cystideæ._--among the additions which recent research has made to the paleontology of the oldest silurian rocks, none are more remarkable than the radiated animals called _cystideæ_. their structure and relations were first elucidated in an essay published by von buch at berlin in . they are usually met with as spheroidal bodies covered with polygonal plates, with a mouth on the upper side, and a point of attachment for a stem _b_ (which is almost always broken off) on the lower. (see fig. .) they are considered by professor e. forbes as intermediate between the crinoids and echinoderms. the _sphæronites_ here represented (fig. .) occurs in the llandeilo beds in wales.[ -a] [illustration: fig. . _sphæronites balticus_, eichwald. (of the family _cystideæ_.) _a._ mouth. _b._ point of attachment of stem. lower silurian, shole's hook and bala.] _thickness and unconformability of silurian strata._--according to the observation of our government surveyors in north wales, the lower silurian strata of that region attain, in conjunction with the contemporaneous volcanic rocks, the extraordinary thickness of , feet. one of the groups, called the trappean, consisting of slates and associated volcanic ash and greenstone, is , feet thick. another series, called the bala group, composed of slates and grits with an impure limestone rich in organic remains, is , feet thick.[ -a] throughout north wales the wenlock shales rest unconformably upon the caradoc sandstones; and the caradoc is in its turn unconformable to the llandeilo beds, showing a considerable interval of time between the deposition of this group and that of the formations next above and below it. the caradoc sandstone in the neighbourhood of the longmynd hills in shropshire, appears to professor e. forbes to have been a deep-sea deposit formed around the margin of high and steep land. that land consisted partly of upraised llandeilo flags and partly of rocks of still older date.[ -b] such evidence of the successive disturbance of strata during the silurian period in great britain is what we might look for when we have discovered the signs of so grand a series of volcanic eruptions as the contemporaneous greenstones and tuffs of the welsh mountains afford. _silurian strata of the united states._ the position of some of these strata, where they are bent and highly inclined in the appalachian chain, or where they are nearly horizontal to the west of that chain, is shown in the section, fig. . p. . but these formations can be studied still more advantageously north of the same line of section, in the states of new york, ohio, and other regions north and south of the great canadian lakes. here they are found, as in russia, in horizontal position, and are more rich in well-preserved fossils than in almost any spot in europe. the american strata may readily be divided into upper and lower silurian, corresponding in age and fossils to the european divisions bearing the same names. the subordinate members of the new york series, founded on lithological and geographical considerations, are most useful in the united states, but even there are only of local importance. some few of them, however, tally very exactly with english divisions, as for example the limestone, over which the niagara is precipitated at the great cataract, which, with its underlying shales, agrees paleontologically with the wenlock limestone and shale of siluria. there is also a marked general correspondence in the succession of fossil forms, and even species, as we trace the organic remains downwards from the highest to the lowest beds. mr. d. sharpe, in his report on the mollusca collected by me from these strata in north america[ -c], has concluded that the number of species common to the silurian rocks, on both sides of the atlantic, is between and per cent.; a result which, although no doubt liable to future modification, when a larger comparison shall have been made, proves, nevertheless, that many of the species had a wide geographical range. it seems that comparatively few of the gasteropods and lamellibranchiate bivalves of north america can be identified specifically with european fossils, while no less than two-fifths of the brachiopoda are the same. in explanation of these facts, it is suggested, that most of the recent brachiopoda (especially the orthidiform ones) are inhabitants of deep water, and may have had a wider geographical range than shells living near shore. the predominance of bivalve mollusca of this peculiar class has caused the silurian period to be sometimes styled the age of brachiopods. _whether the silurian rocks are of deep-water origin._--the grounds relied upon by professor e. forbes, for inferring that the larger part of the silurian fauna is indicative of a sea more than fathoms deep, are the following: first, the small size of the greater number of conchifera; secondly, the paucity of pectinibranchiata (or spiral univalves); thirdly, the great number of floaters, such as _bellerophon_, _orthoceras_, &c.; fourthly, the abundance of orthidiform brachiopoda; fifthly, the absence or great rarity of fossil fish. it is doubtless true that some living _terebratulæ_, on the coast of australia, inhabit shallow water; but all the known species, allied in form to the extinct _orthis_, inhabit the depths of the sea. it should also be remarked that mr. forbes, in advocating these views, was well aware of the existence of shores, bounding the silurian sea in shropshire, and of the occurrence of littoral species of this early date in the northern hemisphere. such facts are not inconsistent with his theory; for he has shown, in another work, how, on the coast of lycia, deep-sea strata are at present forming in the mediterranean, in the vicinity of high and steep land. had we discovered the ancient delta of some large silurian river, we should doubtless have known more of the shallow, and brackish water, and fluviatile animals, and of the terrestrial flora of the period under consideration. to assume that there were no such deltas in the silurian world, would be almost as gratuitous an hypothesis, as for the inhabitants of the coral islands of the pacific to indulge in a similar generalization respecting the actual condition of the globe.[ -a] _mineral character of silurian strata._ in lithological character, the silurian strata vary greatly when we trace them through europe and north america. the shales called mudstones are as little altered from some deposits, found in recent submarine banks, as are those of many tertiary formations. we meet with red sandstone and red marl, with gypsum and salt, of upper silurian date, in the niagara district, which might be mistaken for trias. the whitish granular sandstone at the base of the silurian series in sweden resembles the tertiary siliceous grit of fontainebleau. the calcareous grit, oolite, and pisolite of upper silurian age in gothland, are described by sir r. murchison as singularly like rocks of the oolitic period near cheltenham; and, not to cite more examples, the wenlock or dudley limestone often resembles a modern coral-reef. if, therefore, uniformity of aspect has been thought characteristic of rocks of this age, the idea must have arisen from the similarity of feature acquired by strata subject to metamorphic action. this influence, seeing that the causes of change are always shifting the theatre of their principal development, must be multiplied throughout a wider geographical area by time, and become more general in any given system of rocks in proportion to their antiquity. we are now acquainted with dense groups of eocene slates in the alps, which were once mistaken by experienced geologists for transition or silurian formations. the error arose from attaching too great importance to mineral character as a test of age, for the tertiary slates in question having acquired that crystalline texture which is in reality most prevalent in the most ancient sedimentary formations. cambrian group. below the silurian strata in north wales, and in the region of the cumberland lakes, there are some slaty rocks, devoid of organic remains, or in which a few obscure traces only of fossils have been detected (for which the names of cambrian and cumbrian have been proposed). whether these will ever be entitled by the specific distinctness of their fossils to rank as independent groups, we have not yet sufficient data to determine. * * * * * tabular view of fossiliferous strata, _showing the order of superposition or chronological succession of the principal european groups_. i. post-tertiary. a. post-pliocene. periods and groups. examples. observations. . recent. { peat mosses and shell-marl, } all the imbedded shells, { with bones of land animals, } freshwater and marine, { human remains, and works } of living species, { of art. } with occasional { } human remains and { newer parts of modern deltas } works of art. { and coral reefs. } . post-pliocene. { clay, marl, and volcanic tuff } all the shells of living { of ischia, p. . } species. no human { } remains or works { loess of the rhine, p. . } of art. bones of { } quadrupeds, partly { newer part of boulder } of extinct species. { formation, with erratics, } { p. . } ii. tertiary. b. pliocene. . newer pliocene { boulder formation or drift of { three-fourths of the or pleistocene. { northern europe and north { fossil shells of { america, chaps. . & . { existing species. { { { cavern deposits and osseous { a majority of the { breccias, p. . { mammalia extinct; { { but the genera { fluvio-marine crag of norwich, { corresponding with { p. . { those now surviving in { { the same great { limestone of girgenti, { geographical and { in sicily, p. . { zoological province, { p. . { { during part of this { period icebergs { frequent in the seas { of the northern { hemisphere, and { glaciers on hills { of moderate height. . older pliocene. { red and coralline crag of { a third or more of the { suffolk, p. . { species of mollusca { { extinct. { subapennine beds, p. . { { nearly, if not all, the { mammalia extinct. c. miocene. . miocene. { faluns of touraine, p. . { about two-thirds of the { { species of shells { part of bordeaux beds, p. . { extinct. { { { part of molasse of { the recent species of { switzerland, p. . { shells often not { found in the { adjoining seas, but { in warmer latitudes. { { all the mammalia { extinct. d. eocene. . upper eocene. { upper marine of paris basin, } fossil shells of the { fontainebleau sandstone, } eocene period, with { p. . } very few exceptions, { } extinct. those which { upper freshwater and millstone } are identified with { of same. } living species rarely { kleyn spauwen beds, p. . } belong to neighbouring { } regions. { hermsdorf tile-clay, near } { berlin. } all the mammalia of { } extinct species, and { mayence tertiary strata, } the greater part of { p. . } them of extinct { } genera. { freshwater beds of limagne } { d'auvergne, p. . } plants of upper eocene, } indicating a south . middle eocene. { paris gypsum with } european or { paleotherium, &c., p. . } mediterranean climate; { } those of lower eocene, { freshwater and fluvio-marine } a tropical climate. { beds of headon hill, isle } { of wight, p. . } { } { barton beds, hants, p. . } { } { calcaire grossier, paris, } { p. . } { } { bagshot and bracklesham beds, } { surrey and sussex, p. . } } . lower eocene. { london clay proper of highgate } { hill and sheppey,--bognor } { beds, sussex, p. . } { } { sables inférieurs, and lits } { coquilliers of paris basin, } { p. . } { } { mottled and plastic clays and } { sands of the hampshire and } { london basins, p. . } { } { sables inférieurs and argiles } { plastiques of paris basin, } { p. . } { } { nummulitic formation of the } { alps, p. . } iii. secondary. e. cretaceous. § upper cretaceous. . maestricht { yellowish white limestone of { ammonite, baculite, and beds. { maestricht, p. . { belemnite, associated { { with cypræa, oliva, { coralline limestone of faxoe, { mitra, trochus, &c. { denmark, p. . { large marine saurians. . upper white { white chalk with flints of } marine limestone chalk. { north and south } formed in part of { downs,--surrey and sussex, } decomposed corals. { p. . } . lower white { chalk without flints, and } chalk. { chalk marl, ibid. } . upper { loose sand, with bright green } greensand. { particles, ibid. } { } { firestone of merstham, kent, } { p. . } { } { marly stone, with layers of } { chert, south of isle of } { wight. } . gault. { dark blue marl at base of { numerous extinct genera { chalk escarpment,--kent { of conchiferous { and sussex, p. . { cephalopoda, hamite, { scaphite, ammonite, &c. §§ lower cretaceous. . lower { sand with green matter,--weald } species of shells, &c., greensand. { of kent and sussex, } nearly all distinct { p. . } from those of upper { } cretaceous; most of { white, yellowish, and } the genera the same. { ferruginous sand, with } { concretions of limestone and } { chert,--atherfield, isle } { of wight. } { } { limestone called kentish rag } f. wealden. . weald clay. { clay with occasional bands of { of freshwater origin. { limestone,--weald of kent, { shells of { surrey, and sussex, p. . { pulmoniferous { mollusca, and of { cypris. land reptiles. . hastings sand. { sand with calciferous grit and { freshwater with { clay,--hastings, sussex, { intercalated bed of { cuckfield, kent, p. . { brackish and salt { water origin. shells { of fluviatile and { lacustrine genera. { reptiles of the genera { pterodactyle, { iguanodon, { megalosaurus, { plesiosaurus, trionyx, { and emys. . purbeck beds. limestones, calcareous slates { chiefly freshwater, and and marls, p. . { divisible into three { groups, each { containing distinct { species of freshwater { mollusca and of { entomostraca. { alternations of { deposits formed in { fresh, brackish, and { marine water, and of { ancient soils formed { on land and retaining { roots of trees. { plants chiefly cycads { and conifers, p. . g. oolite. . upper oolite. { _a._ portland building stone, } ammonites and belemnites { p. . } numerous. { } { _b._ portland sand. } large saurians, as { } pterodactyles, { _c._ kimmeridge clay, } plesiosaurs, { dorsetshire, p. . } ichthyosaurs. } . middle oolite. { _a._ coral rag, p. . } no cetaceans yet known, { calcareous freestones, } but three species of { oolitic, often full of } terrestrial mammalia, { corals. oxfordshire. } p. , . { } preponderance of { _b._ oxford clay--dark blue } ganoid fish. the { clay,--oxfordshire and } plants chiefly cycads, { midland counties, p. . } conifers, and ferns, } with a few palms. . lower oolite. { _a._ cornbrash and forest } { marble, wiltshire, p. . } { } { _b._ great oolite and } { stonesfield slate,--bath, } { bradford, stonesfield near } { woodstock, oxfordshire, } { p. . } { } { _c._ fuller's earth,--clay } { containing fuller's earth } { near bath, p. . } { } { _d._ inferior oolite, } { calcareous freestone, and } { yellow sands,--cotteswold } { hills, dundry hill, near } { bristol, p. . } h. lias. . lias. { argillaceous limestone, marl { mollusca, reptiles, { and clay,--lyme regis, { and fish of genera { dorsetshire, p. . { analogous to the { oolitic. i. trias. . upper trias. { keuper of germany, or } batrachian reptiles, { variegated marls--red, grey, } _e.g._ labyrinthodon, { green, blue, and white marls } rhyncosaurus, &c. { and sandstones with } cephalopoda: { gypsum--würtemberg, bone-bed } ceratites. no { of axmouth, dorset, p. . } belemnites. plants: } ferns, cycads, } conifers. . middle trias { compact greyish limestone } with equisetites or { with beds of dolomite and } and calamite. muschelkalk. { gypsum,--north of germany, } { p. . wanting in } { england. } . lower trias. { variegated or bunter sandstone } plants different for { of germans--red and white } the most part from { spotted sandstone with } those of the upper { gypsum and rock-salt, p. } trias. { } { part of new red sandstone of } { of cheshire with rock-salt, } { p. . } iv. primary. k. permian. . upper permian. { yellow magnesian limestone, } organic remains, both { yorkshire and durham, } animal and vegetable, { p. . } more allied to primary { } than to secondary { zechstein of thuringia, upper } periods. { part of permian beds, } { russia. } . lower permian. { _a._ marl slate of durham and } thecodont saurians. { thuringia. } heterocercal fish of { } genus palæoniscus, &c. { _b._ lower new red sandstone } { of north of england and } { rothliegendes of germany. } { } { _a._ and _b._ lower part of } { permian beds, russia, } { p. . } l. carboniferous. . coal measures. { _a._ strata of sandstone and } great thickness of { shale, with beds of } strata of { coal,--s. wales and } fluvio-marine origin, { northumberland, p. . } with beds of coal of { } vegetable origin, { _b._ millstone grit,--s. } based on soils { wales, bristol coal-field, } retaining the roots { yorkshire, p. . } of trees. } } oldest of known reptiles } or archegosaurus. } sauroid fish. . mountain { carboniferous or mountain { brachiopoda of genus limestone. { limestone, with marine { productus. { shells and corals. { { { cephalopoda of genera { mendip hills, and many parts { cyrtoceras, goniatite, { of ireland, p. . { orthoceras. { { crustaceans of the { genus phillipsia. { { crinoideans abundant. m. devonian. . upper { _a._ yellow sandstone of dura } tribe of fish with hard devonian. { den, fife. } coverings like { } chelonians, { _b._ red sandstone and marl } pterichthys, { with cornstone of } pamphractus, &c.; { herefordshire and } also of genera { forfarshire. } cephalaspis, { } holoptichius, &c. { paving and roofing-stone, } { forfarshire. } no reptiles yet known. { } { upper part of devonian beds } { of south devon. } . lower { grey sandstone with } fish, partly of same devonian. { ichthyolites,--caithness, } genera, but of { cromarty, and orkney, lower } distinct species from { part of devonian beds of } those in upper { south devon, and green } devonian; also { chloritic slates of } osteolepis, { cornwall, limestone of } coccosteus, { gerolstein, eifel. } glyptolepis, } dipterus, &c. n. silurian. . upper { _a._ tilestone of brecon and { oldest of fossil fish silurian. { caermarthen. { yet discovered. { { { _b._ limestone and shale, { trilobites and { ludlow, shropshire. { graptolites abundant. { { { _c._ wenlock or dudley { brachiopoda very { limestone. { numerous. { { cephalopoda: { bellerophon, { orthoceras. { same genera of . lower { _a._ caradoc sandstone, caer { invertebrate animals silurian. { caradoc, shropshire. { as in upper silurian, { { but species chiefly { _b._ llandeilo flags, { distinct. trinucleus { calcareous flags and { caractaci, cystideæ, { schists,--builth, { p. . { radnorshire, llandeilo, { { caermarthenshire. { no land plants yet { known. { { footprints of tortoise, { see note, p. . footnotes: [ -a] murchison, silurian system, p. , . [ -a] silurian system, pl. . bis. fig. . b. [ -a] quart. geol. journ., vol. ii. p. .; and memoirs of geol. survey, vol. ii. p. . [ -a] quart. geol. journ., vol. iv. p. . [ -b] ibid., . [ -c] ibid., . [ -a] since this was written, mr. logan has discovered chelonian footprints in the lowest fossiliferous beds of the silurian series, near montreal, in canada. professor owen inclines to refer them to the genus _emys_.--_quart. journ. g. s._, vol. vii. p. lxxvi. chapter xxviii. volcanic rocks. trap rocks--name, whence derived--their igneous origin at first doubted--their general appearance and character--volcanic cones and craters, how formed--mineral composition and texture of volcanic rocks--varieties of felspar--hornblende and augite--isomorphism--rocks, how to be studied--basalt, greenstone, trachyte, porphyry, scoria, amygdaloid, lava, tuff--alphabetical list, and explanation of names and synonyms, of volcanic rocks--table of the analyses of minerals most abundant in the volcanic and hypogene rocks. the aqueous or fossiliferous rocks having now been described, we have next to examine those which may be called volcanic, in the most extended sense of that term. suppose _a a_ in the annexed diagram, to represent the crystalline formations, such as the granitic and metamorphic; _b b_ the fossiliferous strata; and _c c_ the volcanic rocks. these last are sometimes found, as was explained in the first chapter, breaking through _a_ and _b_, sometimes overlying both, and occasionally alternating with the strata _b b_. they also are seen, in some instances, to pass insensibly into the unstratified division of _a_, or the plutonic rocks. [illustration: fig. . cross section. _a._ hypogene formations, stratified and unstratified. _b._ aqueous formations. _c._ volcanic rocks.] when geologists first began to examine attentively the structure of the northern and western parts of europe, they were almost entirely ignorant of the phenomena of existing volcanos. they also found certain rocks, for the most part without stratification, and of a peculiar mineral composition, to which they gave different names, such as basalt, greenstone, porphyry, and amygdaloid. all these, which were recognized as belonging to one family, were called "trap" by bergmann, from _trappa_, swedish for a flight of steps--a name since adopted very generally into the nomenclature of the science; for it was observed that many rocks of this class occurred in great tabular masses of unequal extent, so as to form a succession of terraces or steps on the sides of hills. this configuration appears to be derived from two causes. first, the abrupt original terminations of sheets of melted matter, which have spread, whether on the land or bottom of the sea, over a level surface. for we know, in the case of lava flowing from a volcano, that a stream, when it has ceased to flow, and grown solid, very commonly ends in a steep slope, as at _a_, fig. . but, secondly, the step-like appearance arises more frequently from the mode in which horizontal masses of igneous rock, such as _b c_, intercalated between aqueous strata, have, subsequently to their origin, been exposed, at different heights, by denudation. such an outline, it is true, is not peculiar to trap rocks; great beds of limestone, and other hard kinds of stone, often presenting similar terraces and precipices: but these are usually on a smaller scale, or less numerous, than the volcanic _steps_, or form less decided features in the landscape, as being less distinct in structure and composition from the associated rocks. [illustration: fig. . step-like appearance of trap.] although the characters of trap rocks are greatly diversified, the beginner will easily learn to distinguish them as a class from the aqueous formations. sometimes they present themselves, as already stated, in tabular masses, which are not divided into strata: sometimes in shapeless lumps and irregular cones, forming chains of small hills. often they are seen in dikes and wall-like masses, intersecting fossiliferous beds. the rock is occasionally found divided into columns, often decomposing into balls of various sizes, from a few inches to several feet in diameter. the decomposing surface very commonly assumes a coating of a rusty iron colour, from the oxidation of ferruginous matter, so abundant in the traps in which augite or hornblende occur; or, in the felspathic varieties of trap, it acquires a white opaque coating, from the bleaching of the mineral called felspar. on examining any of these volcanic rocks, where they have not suffered disintegration, we rarely fail to detect a crystalline arrangement in one or more of the component minerals. sometimes the texture of the mass is cellular or porous, or we perceive that it has once been full of pores and cells, which have afterwards become filled with carbonate of lime, or other infiltrated mineral. most of the volcanic rocks produce a fertile soil by their disintegration. it seems that their component ingredients, silica, alumina, lime, potash, iron, and the rest, are in proportions well fitted for vegetation. as they do not effervesce with acids, a deficiency of calcareous matter might at first be suspected; but although _the carbonate_ of lime is rare, except in the nodules of amygdaloids, yet it will be seen that lime sometimes enters largely into the composition of augite and hornblende. (see table, p. .) _cones and craters._--in regions where the eruption of volcanic matter has taken place in the open air, and where the surface has never since been subjected to great aqueous denudation, cones and craters constitute the most striking peculiarity of this class of formations. many hundreds of these cones are seen in central france, in the ancient provinces of auvergne, velay, and vivarais, where they observe, for the most part, a linear arrangement, and form chains of hills. although none of the eruptions have happened within the historical era, the streams of lava may still be traced distinctly descending from many of the craters, and following the lowest levels of the existing valleys. the origin of the cone and crater-shaped hill is well understood, the growth of many having been watched during volcanic eruptions. a chasm or fissure first opens in the earth, from which great volumes of steam and other gases are evolved. the explosions are so violent as to hurl up into the air fragments of broken stone, parts of which are shivered into minute atoms. at the same time melted stone or _lava_ usually ascends through the chimney or vent by which the gases make their escape. although extremely heavy, this lava is forced up by the expansive power of entangled gaseous fluids, chiefly steam or aqueous vapour, exactly in the same manner as water is made to boil over the edge of a vessel when steam has been generated at the bottom by heat. large quantities of the lava are also shot up into the air, where it separates into fragments, and acquires a spongy texture by the sudden enlargement of the included gases, and thus forms _scoriæ_, other portions being reduced to an impalpable powder or dust. the showering down of the various ejected materials round the orifice of eruption gives rise to a conical mound, in which the successive envelopes of sand and scoriæ form layers, dipping on all sides from a central axis. in the mean time a hollow, called a _crater_, has been kept open in the middle of the mound by the continued passage upwards of steam and other gaseous fluids. the lava sometimes flows over the edge of the crater, and thus thickens and strengthens the sides of the cone; but sometimes it breaks it down on one side, and often it flows out from a fissure at the base of the hill (see fig. .).[ -a] [illustration: fig. . part of the chain of extinct volcanos called the monts dome, auvergne. (scrope.)] _composition and nomenclature._--before speaking of the connection between the products of modern volcanos and the rocks usually styled trappean, and before describing the external forms of both, and the manner and position in which they occur in the earth's crust, it will be desirable to treat of their mineral composition and names. the varieties most frequently spoken of are basalt, greenstone, syenitic greenstone, clinkstone, claystone, and trachyte; while those founded chiefly on peculiarities of texture, are porphyry, amygdaloid, lava, tuff, scoriæ, and pumice. it may be stated generally, that all these are mainly composed of two minerals, or families of simple minerals, _felspar_ and _hornblende_; some almost entirely of hornblende, others of felspar. these two minerals may be regarded as two groups, rather than species. felspar, for example, may be, first, common felspar, that is to say, potash-felspar, in which the alkali is potash (see table, p. .); or, secondly, albite, that is to say, soda-felspar, where the alkali is soda instead of potash; or, thirdly, labrador-felspar (labradorite), which differs not only in its iridescent hues, but also in its angle of fracture or cleavage, and its composition. we also read much of two other kinds, called glassy felspar and compact felspar, which, however, cannot rank as varieties of equal importance, for both the albitic and common felspar appear sometimes in transparent or _glassy_ crystals; and as to compact felspar, it is a compound of a less definite nature, sometimes containing both soda and potash; and which might be called a felspathic paste, being the residuary matter after portions of the original matrix have crystallized. the other group, or _hornblende_, consists principally of two varieties; first, hornblende, and, secondly, augite, which were once regarded as very distinct, although now some eminent mineralogists are in doubt whether they are not one and the same mineral, differing only as one crystalline form of native sulphur differs from another. the history of the changes of opinion on this point is curious and instructive. werner first distinguished augite from hornblende; and his proposal to separate them obtained afterwards the sanction of haüy, mohs, and other celebrated mineralogists. it was agreed that the form of the crystals of the two species were different, and their structure, as shown by _cleavage_, that is to say, by breaking or cleaving the mineral with a chisel, or a blow of the hammer, in the direction in which it yields most readily. it was also found by analysis that augite usually contained more lime, less alumina, and no fluoric acid; which last, though not always found in hornblende, often enters into its composition in minute quantity. in addition to these characters, it was remarked as a geological fact, that augite and hornblende are very rarely associated together in the same rock; and that when this happened, as in some lavas of modern date, the hornblende occurs in the mass of the rock, where crystallization may have taken place more slowly, while the augite merely lines cavities where the crystals may have been produced rapidly. it was also remarked, that in the crystalline slags of furnaces, augitic forms were frequent, the hornblendic entirely absent; hence it was conjectured that hornblende might be the result of slow, and augite of rapid cooling. this view was confirmed by the fact, that mitscherlich and berthier were able to make augite artificially, but could never succeed in forming hornblende. lastly, gustavus rose fused a mass of hornblende in a porcelain furnace, and found that it did not, on cooling, assume its previous shape, but invariably took that of augite. the same mineralogist observed certain crystals in rocks from siberia which presented a hornblende _cleavage_, while they had the external form of augite. if, from these data, it is inferred that the same substance may assume the crystalline forms of hornblende or augite indifferently, according to the more or less rapid cooling of the melted mass, it is nevertheless certain that the variety commonly called augite, and recognized by a peculiar crystalline form, has usually more lime in it, and less alumina, than that called hornblende, although the quantities of these elements do not seem to be always the same. unquestionably the facts and experiments above mentioned show the very near affinity of hornblende and augite; but even the convertibility of one into the other by melting and recrystallizing, does not perhaps demonstrate their absolute identity. for there is often some portion of the materials in a crystal which are not in perfect chemical combination with the rest. carbonate of lime, for example, sometimes carries with it a considerable quantity of silex into its own form of crystal, the silex being mechanically mixed as sand, and yet not preventing the carbonate of lime from assuming the form proper to it. this is an extreme case, but in many others some one or more of the ingredients in a crystal may be excluded from perfect chemical union; and, after fusion, when the mass recrystallizes, the same elements may combine perfectly or in new proportions, and thus a new mineral may be produced. or some one of the gaseous elements of the atmosphere, the oxygen for example, may, when the melted matter reconsolidates, combine with some one of the component elements. the different quantity of the impurities or refuse above alluded to, which may occur in all but the most transparent and perfect crystals, may partly explain the discordant results at which experienced chemists have arrived in their analysis of the same mineral. for the reader will find that a mineral determined to be the same by its physical characters, crystalline form, and optical properties, has often been declared by skilful analyzers to be composed of distinct elements. (see the table at p. .) this disagreement seemed at first subversive of the atomic theory, or the doctrine that there is a fixed and constant relation between the crystalline form and structure of a mineral, and its chemical composition. the apparent anomaly, however, which threatened to throw the whole science of mineralogy into confusion, was in a great degree reconciled to fixed principles by the discoveries of professor mitscherlich at berlin, who ascertained that the composition of the minerals which had appeared so variable, was governed by a general law, to which he gave the name of _isomorphism_ (from +isos+, _isos_, equal, and +morphê+, _morphe_, form). according to this law, the ingredients of a given species of mineral are not absolutely fixed as to their kind and quality; but one ingredient may be replaced by an equivalent portion of some analogous ingredient. thus, in augite, the lime may be in part replaced by portions of protoxide of iron, or of manganese, while the form of the crystal, and the angle of its cleavage planes, remain the same. these vicarious substitutions, however, of particular elements cannot exceed certain defined limits. having been led into this digression on the recent progress of mineralogy, i may here observe that the geological student must endeavour as soon as possible to familiarize himself with the characters of five at least of the most abundant simple minerals of which rocks are composed. these are, felspar, quartz, mica, hornblende, and carbonate of lime. this knowledge cannot be acquired from books, but requires personal inspection, and the aid of a teacher. it is well to accustom the eye to know the appearance of rocks under the lens. to learn to distinguish felspar from quartz is the most important step to be first aimed at. in general we may know the felspar because it can be scratched with the point of a knife, whereas the quartz, from its extreme hardness, receives no impression. but when these two minerals occur in a granular and uncrystallized state, the young geologist must not be discouraged if, after considerable practice, he often fails to distinguish them by the eye alone. if the felspar is in crystals, it is easily recognized by its cleavage: but when in grains the blow-pipe must be used, for the edges of the grains can be rounded in the flame, whereas those of _quartz_ are infusible. if the geologist is desirous of distinguishing the three varieties of felspar above enumerated, or hornblende from augite, it will often be necessary to use the reflecting goniometer as a test of the angle of cleavage, and shape of the crystal. the use of this instrument will not be found difficult. the external characters and composition of the felspars are extremely different from those of augite or hornblende; so that the volcanic rocks in which either of these minerals decidedly predominates, are easily recognized. but there are mixtures of the two elements in every possible proportion, the mass being sometimes exclusively composed of felspar, at other times solely of augite, or, again, of both in equal quantities. occasionally, the two extremes, and all the intermediate gradations, may be detected in one continuous mass. nevertheless there are certain varieties or compounds which prevail so largely in nature, and preserve so much uniformity of aspect and composition, that it is useful in geology to regard them as distinct rocks, and to assign names to them, such as basalt, greenstone, trachyte, and others, already mentioned. _basalt._--as an example of rocks in which augite greatly prevails, basalt may first be mentioned. although we are more familiar with this term than with that of any other kind of trap, it is difficult to define it, the name having been used so vaguely. it has been very generally applied to any trap rock of a black, bluish, or leaden-grey colour, having a uniform and compact texture. most strictly, it consists of an intimate mixture of augite, felspar, and iron, to which a mineral of an olive green colour, called olivine, is often superadded, in distinct grains or nodular masses. the iron is usually magnetic, and is often accompanied by another metal, titanium. augite is the predominant mineral, the felspar being in much smaller proportions. there is no doubt that many of the fine-grained and dark-coloured trap rocks, called basalt, contained hornblende in the place of augite; but this will be deemed of small importance after the remarks above made. other minerals are occasionally found in basalt; and this rock may pass insensibly into almost every variety of trap, especially into greenstone, clinkstone, and wacké, which will be presently described. _greenstone_, or _dolerite_, is usually defined as a granular rock, the constituent parts of which are hornblende and imperfectly crystallized felspar; the felspar being more abundant than in basalt; and the grains or crystals of the two minerals more distinct from each other. this name may also be extended to those rocks in which augite is substituted for hornblende (the dolorite of some authors), or to those in which albite replaces common felspar, forming the rock sometimes called andesite. _syenitic greenstone._--the highly crystalline compounds of the same two minerals, felspar and hornblende, having a granitiform texture, and with occasionally some quartz accompanying, may be called syenitic greenstone, a rock which frequently passes into ordinary trap, and as frequently into granite. _trachyte._--a porphyritic rock of a whitish or greyish colour, composed principally of glassy felspar, with crystals of the same, generally with some hornblende and some titaniferous iron. in composition it is extremely different from basalt, this being a felspathic, as the other is an augitic, rock. it has a peculiar rough feel, whence the name +trachys+, _trachus_, rough. some varieties of trachyte contain crystals of quartz. [illustration: fig. . porphyry. white crystals of felspar in a dark base of hornblende and felspar.] _porphyry_ is merely a certain form of rock, very characteristic of the volcanic formations. when distinct crystals of one or more minerals are scattered through an earthy or compact base, the rock is termed a porphyry (see fig. .). thus trachyte is porphyritic; for in it, as in many modern lavas, there are crystals of felspar; but in some porphyries the crystals are of augite, olivine, or other minerals. if the base be greenstone, basalt, or pitchstone, the rock may be denominated greenstone-porphyry, pitchstone-porphyry, and so forth. _amygdaloid._--this is also another form of igneous rock, admitting of every variety of composition. it comprehends any rock in which round or almond-shaped nodules of some mineral, such as agate, calcedony, calcareous spar, or zeolite, are scattered through a base of wacké, basalt, greenstone, or other kind of trap. it derives its name from the greek word _amygdala_, an almond. the origin of this structure cannot be doubted, for we may trace the process of its formation in modern lavas. small pores or cells are caused by bubbles of steam and gas confined in the melted matter. after or during consolidation, these empty spaces are gradually filled up by matter separating from the mass, or infiltered by water permeating the rock. as these bubbles have been sometimes lengthened by the flow of the lava before it finally cooled, the contents of such cavities have the form of almonds. in some of the amygdaloidal traps of scotland, where the nodules have decomposed, the empty cells are seen to have a glazed or vitreous coating, and in this respect exactly resemble scoriaceous lavas, or the slags of furnaces. [illustration: fig. . scoriaceous lava in part converted into an amygdaloid. montagne de la veille, department of puy de dome, france.] the annexed figure represents a fragment of stone taken from the upper part of a sheet of basaltic lava in auvergne. one half is scoriaceous, the pores being perfectly empty; the other part is amygdaloidal, the pores or cells being mostly filled up with carbonate of lime, forming white kernels. _scoriæ_ and _pumice_ may next be mentioned as porous rocks, produced by the action of gases on materials melted by volcanic heat. _scoriæ_ are usually of a reddish-brown and black colour, and are the cinders and slags of basaltic or augitic lavas. _pumice_ is a light, spongy, fibrous substance, produced by the action of gases on trachytic and other lavas; the relation, however, of its origin to the composition of lava is not yet well understood. von buch says that it never occurs where only labrador-felspar is present. _lava._--this term has a somewhat vague signification, having been applied to all melted matter observed to flow in streams from volcanic vents. when this matter consolidates in the open air, the upper part is usually scoriaceous, and the mass becomes more and more stony as we descend, or in proportion as it has consolidated more slowly and under greater pressure. at the bottom, however, of a stream of lava, a small portion of scoriaceous rock very frequently occurs, formed by the first thin sheet of liquid matter, which often precedes the main current, or in consequence of the contact with water in or upon the damp soil. the more compact lavas are often porphyritic, but even the scoriaceous part sometimes contains imperfect crystals, which have been derived from some older rocks, in which the crystals pre-existed, but were not melted, as being more infusible in their nature. although melted matter rising in a crater, and even that which enters rents on the side of a crater, is called lava, yet this term belongs more properly to that which has flowed either in the open air or on the bed of a lake or sea. if the same fluid has not reached the surface, but has been merely injected into fissures below ground, it is called trap. there is every variety of composition in lavas; some are trachytic, as in the peak of teneriffe; a great number are basaltic, as in vesuvius and auvergne; others are andesitic, as those of chili; some of the most modern in vesuvius consist of green augite, and many of those of etna of augite and labrador-felspar.[ -a] _trap tuff, volcanic tuff._--small angular fragments of the scoriæ and pumice, above mentioned, and the dust of the same, produced by volcanic explosions, form the tuffs which abound in all regions of active volcanos, where showers of these materials, together with small pieces of other rocks ejected from the crater, fall down upon the land or into the sea. here they often become mingled with shells, and are stratified. such tuffs are sometimes bound together by a calcareous cement, and form a stone susceptible of a beautiful polish. but even when little or no lime is present, there is a great tendency in the materials of ordinary tuffs to cohere together. besides the peculiarity of their composition, some tuffs, or _volcanic grits_, as they have been termed, differ from ordinary sandstones by the angularity of their grains. when the fragments are coarse, the rock is styled a volcanic _breccia_. _tufaceous conglomerates_ result from the intermixture of rolled fragments or pebbles of volcanic and other rocks with tuff. according to mr. scrope, the italian geologists confine the term _tuff_, or tufa, to felspathose mixtures, and those composed principally of pumice, using the term _peperino_ for the basaltic tuffs.[ -b] the peperinos thus distinguished are usually brown, and the tuffs grey or white. we meet occasionally with extremely compact beds of volcanic materials, interstratified with fossiliferous rocks. these may sometimes be tuffs, although their density or compactness is such as to cause them to resemble many of those kinds of trap which are found in ordinary dikes. the chocolate-coloured mud, which was poured for weeks out of the crater of graham's island, in the mediterranean, in , must, when unmixed with other materials, have constituted a stone heavier than granite. each cubic inch of the impalpable powder which has fallen for days through the atmosphere, during some modern eruptions, has been found to weigh, without being compressed, as much as ordinary trap rocks, and to be often identical with these in mineral composition. the fusibility of the igneous rocks generally exceeds that of other rocks, for there is much alkaline matter and lime in their composition, which serves as a flux to the large quantity of silica, which would be otherwise so refractory an ingredient. it is remarkable that, notwithstanding the abundance of this silica, quartz, that is, crystalline silica, is usually wanting in the volcanic rocks, or is present only as an occasional mineral, like mica. the elements of mica, as of quartz, occur in lava and trap; but the circumstances under which these rocks are formed are evidently unfavourable to the development of mica and quartz, minerals so characteristic of the hypogene formations. it would be tedious to enumerate all the varieties of trap and lava which have been regarded by different observers as sufficiently abundant to deserve distinct names, especially as each investigator is too apt to exaggerate the importance of local varieties which happen to prevail in districts best known to him. it will be useful, however, to subjoin here, in the form of a glossary, an alphabetical list of the names and synonyms most commonly in use, with brief explanations, to which i have added a table of the analysis of the simple minerals most abundant in the volcanic and hypogene rocks. _explanation of the names, synonyms, and mineral composition of the more abundant volcanic rocks._ amphibolite. _see_ hornblende rock, amphibole being haüy's name for hornblende. amygdaloid. a particular form of volcanic rock; _see_ p. . augite rock. a kind of basalt or greenstone, composed wholly or principally of granular augite. (_leonhard's mineralreich_, d edition, p. .) augitic-porphyry. crystals of labrador-felspar and of augite, in a green or dark grey base. (_rose_, _ann. des mines_, tom. . p. . .) basalt. chiefly augite--an intimate mixture of augite and felspar with magnetic iron, olivine, &c. _see_ p. . the yellowish green mineral called olivine, can easily be distinguished from yellowish felspar by its infusibility, and having no cleavage. the edges turn brown in the flame of the blow-pipe. basanite. name given by alex. brongniart to a rock, having a base of basalt, with more or less distinct crystals of augite disseminated through it. claystone and claystone-porphyry. an earthy and compact stone, usually of a purplish colour, like an indurated clay; passes into hornstone; generally contains scattered crystals of felspar and sometimes of quartz. clinkstone. _syn._ phonolite, fissile petrosilex; a greenish or greyish rock, having a tendency to divide into slabs and columns; hard, with clean fracture, ringing under the hammer; principally composed of compact felspar, and, according to gmelin, of felspar and mesotype. (_leonhard_, _mineralreich_, p. .) a rock much resembling clinkstone, and called by some petrosilex, contains a considerable percentage of quartz and felspar. as both trachyte and basalt pass into clinkstone, the rock so called must be very various in composition. compact felspar, which has also been called petrosilex; the rock so called includes the hornstone of some mineralogists, is allied to clinkstone, but is harder, more compact, and translucent. it is a varying rock, of which the chemical composition is not well defined, and is perhaps the same as that of clay. (_macculloch's classification of rocks_, p. .) dr. macculloch says, that it contains both potash and soda. cornean. a variety of claystone allied to hornstone. a fine homogeneous paste, supposed to consist of an aggregate of felspar, quartz, and hornblende, with occasionally epidote, and perhaps chlorite; it passes into compact felspar and hornstone. (_de la beche_, _geol. trans._ second series, vol. . p. .) diallage rock. _syn_. euphotide, gabbro, and some ophiolites. compounded of felspar and diallage, sometimes with the addition of serpentine, or mica, or quartz. (_macculloch. ibid_. p. .) diorite. a kind of greenstone, which see. components, felspar and hornblende in grains. according to _rose_, _ann. des mines_, tom. . p. ., _diorite_ consists of albite and hornblende. dioritic-porphyry. a porphyritic greenstone, composed of crystals of albite and hornblende, in a greenish or blackish base. (_rose_, _ibid._ p. .) dolerite. formerly defined as a synonym of greenstone, which see. but, according to rose (_ibid._ p. .), its composition is black augite and labrador-felspar; according to leonhard (_mineralreich_, &c. p. .), augite, labrador-felspar, and magnetic iron. domite. an earthy _trachyte_, found in the puy de dome, in auvergne. euphotide. a mixture of grains of labrador-felspar and diallage. (_rose_, _ibid._ p. .) according to some, this rock is defined to be a mixture of augite or hornblende, and saussurite, a mineral allied to jade. (_allan's mineralogy_, p. .) _see_ diallage rock. felspar-porphyry. _syn._ hornstone-porphyry; a base of felspar, with crystals of felspar, and crystals and grains of quartz. _see_ also hornstone. gabbro, _see_ diallage rock. greenstone. _syn._ dolerite and diorite; components, hornblende and felspar, or augite and felspar in grains. see above, p. . greystone. (graustein of werner.) lead grey and greenish rock, composed of felspar and augite, the felspar being more than seventy-five per cent. (_scrope_, _journ. of sci._ no. . p. .) greystone lavas are intermediate in composition between basaltic and trachytic lavas. hornblende rock. a greenstone, composed principally of granular hornblende, or augite. (_leonhard_, _mineralreich_, &c., p. .) hornstone, hornstone-porphyry. a kind of felspar porphyry (_leonhard_, _ibid._), with a base of hornstone, a mineral approaching near to flint, differing from compact felspar in being infusible. hypersthene rock, a mixture of grains of labrador-felspar and hypersthene (_rose_, _ann. des mines_, tom. . p. .), having the structure of syenite or granite; abundant among the traps of skye. some geologists consider it a greenstone, in which hypersthene replaces hornblende. laterite. a red jaspery rock, composed of silicate of alumina and oxide of iron. abundant in the deccan, in india; and referred to the trap formation; from later, a brick or tile. melaphyre. a variety of black porphyry, the base being black augite with crystals of felspar; from +melas+, _melas_, black. obsidian. vitreous lava like melted glass, nearly allied to pitchstone. ophiolite, sometimes same as diallage rocks (_leonhard_, p. .); sometimes a kind of serpentine. ophite. a green porphyritic rock composed chiefly of hornblende, with crystals of that mineral in a base of the same, mixed with some felspar. it passes into serpentine by a mixture of talc. (_burat's d'aubuisson_, tom. ii. p. .) pearlstone. a volcanic rock, having the lustre of mother of pearl; usually having a nodular structure; intimately related to obsidian, but less glassy. peperino. a form of volcanic tuff, composed of basaltic scoriæ. _see_ p. . petrosilex. _see_ clinkstone and compact felspar. phonolite. _syn._ of clinkstone, which see. pitchstone. vitreous lava, less glassy than obsidian; a blackish green rock resembling glass, having a resinous lustre and appearance of pitch; composition various, usually felspar and augite; passes into basalt; occurs in veins, and in arran forms a dike thirty feet wide, cutting through sandstone; forms the outer walls of some basaltic dikes. porphyry. any rock in which detached crystals of felspar, or of one or more minerals, are diffused through a base. _see_ p. . pozzolana. a kind of tuff. _see_ p. . pumice. a light, spongy, fibrous form of trachyte. _see_ p. . pyroxenic-porphyry, same as augitic-porphyry, pyroxene being haüy's name for augite. scoriÆ. _syn._ volcanic cinders; reddish brown or black porous form of lava. _see_ p. . serpentine. a greenish rock, in which there is much magnesia; usually contains diallage, which is nearly allied to the simple mineral called serpentine. occurs sometimes, though rarely, in dikes, altering the contiguous strata; is indifferently a member of the trappean or hypogene series. syenitic-greenstone; composition, crystals or grains of felspar and hornblende. _see_ p. . tephrine, synonymous with lava. name proposed by alex. brongniart. toadstone. a local name in derbyshire for a kind of wacké, which see. trachyte. chiefly composed of glassy felspar, with crystals of glassy felspar. _see_ p. . trap tuff. _see_ p. . trass. a kind of tuff or mud poured out by lake craters during eruptions; common in the eifel, in germany. tufaceous conglomerate. _see_ p. . tuff. _syn._ trap-tuff, volcanic tuff. _see_ p. . vitreous lava. _see_ pitchstone and obsidian. volcanic tuff. _see_ p. . wackÉ. a soft and earthy variety of trap, having an argillaceous aspect. it resembles indurated clay, and when scratched exhibits a shining streak. whinstone. a scotch provincial term for greenstone and other hard trap rocks. analysis of minerals most abundant in the volcanic and hypogene rocks. silica. alu- mag- lime. pot- soda. iron. manga- remain- mina. nesia. ash. oxide. nese. der. actinolite · -- · -- -- -- · a · c. (bergman) trace albite (rose) · · -- a trace -- · -- -- -- --(mean of · · · · -- · a -- -- analyses) trace augite (rose) · -- · · -- -- · · -- --(mean of · · · · -- -- · · -- analyses) carbonate of -- -- -- · -- -- -- -- -- lime (biot) chiastolite · · · -- -- -- · -- · w. (landgrabe) chlorite · · · -- -- · · -- -- (vauquelin) --(mean of · · · · · -- · -- · w. analyses) diallage · -- · -- -- -- · -- -- (klaproth) --(mean of · · · · -- -- · -- · w. analyses) epidote · · -- · -- -- · · -- (vauquelin) felspar, · · -- · - · -- · -- -- common (vauq.) --(rose) · · -- · · -- · -- -- --(mean of · · -- · · -- · -- -- analyses) garnet · · -- -- -- -- · · -- (klaproth) --(phillips) · · -- · -- -- · -- -- hornblende · · · · a -- · · -- (klap.) trace --(bonsdorff.) · · · · -- -- · · · f. hypersthene · · · · -- -- · a · w. (klaproth) trace labrador- · · -- · -- · · -- · w. felspar (klap.) leucite · · -- -- · -- -- -- -- (klap.) mesotype · · -- · -- · -- -- · w. (gehlen) mica · · · -- · -- · · -- (klaproth) --(vauquelin) · · -- · -- -- · -- -- --(mean of · · -- -- · -- · · -- analyses) olivine · -- · -- -- -- · -- -- (klaproth) schorl or · · · -- · · · · · b. tourmaline (gmelin) --(mean of · · · · · · · · -- analyses) serpentine · · · · -- -- · -- · w. (hisinger) --(mean of · · · · -- -- · -- · w. analyses) steatite · -- · -- -- -- · -- · w. (vauquelin) --(mean of · · · -- -- -- · -- · w. anal. by klap.) talc. · -- · -- · -- · -- -- (klaproth) in the last column of the above table, the letters b. c. f. w. represent boracic acid, carbonic acid, fluoric acid, and water. footnotes: [ -a] for a description and theory of active volcanos, see principles of geology, chaps. xxiv. to xxvii. [ -a] g. rose, ann. des mines, tom. viii. p. . [ -b] geol. trans. vol. ii. p. . d series. chapter xxix. volcanic rocks--_continued_. trap dikes--sometimes project--sometimes leave fissures vacant by decomposition--branches and veins of trap--dikes more crystalline in the centre--foreign fragments of rock imbedded--strata altered at or near the contact--obliteration of organic remains--conversion of chalk into marble--and of coal into coke--inequality in the modifying influence of dikes--trap interposed between strata--columnar and globular structure--relation of trappean rocks to the products of active volcanos--submarine lava and ejected matter corresponds generally to ancient trap--structure and physical features of palma and some other extinct volcanos. having in the last chapter spoken of the composition and mineral characters of volcanic rocks, i shall next describe the manner and position in which they occur in the earth's crust, and their external forms. now the leading varieties, such as basalt, greenstone, trachyte, porphyry, and the rest, are found sometimes in dikes penetrating stratified and unstratified formations, sometimes in shapeless masses protruding through or overlying them, or in horizontal sheets intercalated between strata. _volcanic dikes._--fissures have already been spoken of as occurring in all kinds of rocks, some a few feet, others many yards in width, and often filled up with earth or angular pieces of stone, or with sand and pebbles. instead of such materials, suppose a quantity of melted stone to be driven or injected into an open rent, and there consolidated, we have then a tabular mass resembling a wall, and called a trap dike. it is not uncommon to find such dikes passing through strata of soft materials, such as tuff or shale, which, being more perishable than the trap, are often washed away by the sea, rivers, or rain, in which case the dike stands prominently out in the face of precipices, or on the level surface of a country. (see the annexed figure.[ -a]) [illustration: fig. . dike in inland valley, near the brazen head, madeira.] in the islands of arran, skye, and other parts of scotland, where sandstone, conglomerate, and other hard rocks are traversed by dikes of trap, the converse of the above phenomenon is seen. the dike having decomposed more rapidly than the containing rock, has once more left open the original fissure, often for a distance of many yards inland from the sea-coast, as represented in the annexed view (fig. .). in these instances, the greenstone of the dike is usually more tough and hard than the sandstone; but chemical action, and chiefly the oxidation of the iron, has given rise to the more rapid decay. [illustration: fig. . fissures left vacant by decomposed trap. strathaird, skye. (macculloch.)] there is yet another case, by no means uncommon in arran and other parts of scotland, where the strata in contact with the dike, and for a certain distance from it, have been hardened, so as to resist the action of the weather more than the dike itself, or the surrounding rocks. when this happens, two parallel walls of indurated strata are seen protruding above the general level of the country, and following the course of the dike. [illustration: fig. . trap veins in airdnamurchan.] as fissures sometimes send off branches, or divide into two or more fissures of equal size, so also we find trap dikes bifurcating and ramifying, and sometimes they are so tortuous as to be called veins, though this is more common in granite than in trap. the accompanying sketch (fig. .) by dr. macculloch represents part of a sea-cliff in argyleshire, where an overlying mass of trap, _b_, sends out some veins which terminate downwards. another trap vein, _a a_, cuts through both the limestone, _c_, and the trap, _b_. in fig. ., a ground plan is given of a ramifying dike of greenstone, which i observed cutting through sandstone on the beach near kildonan castle, in arran. the larger branch varies from to feet in width, which will afford a scale of measurement for the whole. [illustration: fig. . ground plan of greenstone dike traversing sandstone. arran.] in the hebrides and other countries, the same masses of trap which occupy the surface of the country far and wide, concealing the subjacent stratified rocks, are seen also in the sea cliffs, prolonged downwards in veins or dikes, which probably unite with other masses of igneous rock at a greater depth. the largest of the dikes represented in the annexed diagram, and which are seen in part of the coast of skye, is no less than feet in width. [illustration: fig. . trap dividing and covering sandstone near suishnish in skye. (macculloch.)] every variety of trap-rock is sometimes found in these dikes, as basalt, greenstone, felspar-porphyry, and more rarely trachyte. the amygdaloidal traps also occur, and even tuff and breccia, for the materials of these last may be washed down into open fissures at the bottom of the sea, or during eruptions on the land may be showered into them from the air. some dikes of trap may be followed for leagues uninterruptedly in nearly a straight direction, as in the north of england, showing that the fissures which they fill must have been of extraordinary length. _dikes more crystalline in the centre._--in many cases trap at the edges or sides of a dike is less crystalline or more earthy than in the centre, in consequence of the melted matter having cooled more rapidly by coming in contact with the cold sides of the fissure; whereas, in the centre, the matter of the dike being kept long in a fluid or soft state, the crystals are slowly formed. in the ancient part of vesuvius, called somma, a thin band of half-vitreous lava is found at the edge of some dikes. at the junction of greenstone dikes with limestone, a _sahlband_, or selvage, of serpentine is occasionally observed. [illustration: fig. . syenitic greenstone dike of næsodden, christiania. _b._ imbedded fragment of crystalline schist surrounded by a band of greenstone.] on the left shore of the fiord of christiania, in norway, i examined, in company with professor keilhau, a remarkable dike of syenitic greenstone, which is traced through silurian strata, until at length, in the promontory of næsodden, it enters mica-schist. fig. . represents a ground plan, where the dike appears paces in width. in the middle it is highly crystalline and granitiform, of a purplish colour, and containing a few crystals of mica, and strongly contrasted with the whitish mica-schist, between which and the syenitic rock there is usually on each side a distinct black band, inches wide, of dark greenstone. when first seen, these bands have the appearance of two accompanying dikes; yet they are, in fact, only the different form which the syenitic materials have assumed where near to or in contact with the mica-schist. at one point, _a_, one of the sahlbands terminates for a space; but near this there is a large detached block, _b_, having a gneiss-like structure, consisting of hornblende and felspar, which is included in the midst of the dike. round this a smaller encircling zone is seen, of dark basalt, or fine-grained greenstone, nearly corresponding to the larger ones which border the dike, but only inch wide. it seems, therefore, evident that the fragment, _b_, has acted on the matter of the dike, probably by causing it to cool more rapidly, in the same manner as the walls of the fissure have acted on a larger scale. the facts, also, illustrate the facility with which a granitiform syenite may pass into ordinary rocks of the volcanic family. [illustration: fig. . greenstone dike, with fragments of gneiss. sorgenfri, christiania.] the fact above alluded to, of a foreign fragment, such as _b_, fig. ., included in the midst of the trap, as if torn off from some subjacent rock or the walls of a fissure, is by no means uncommon. a fine example is seen in another dike of greenstone, feet wide, in the northern suburbs of christiania, in norway, of which the annexed figure is a ground plan. the dike passes through shale, known by its fossils to belong to the silurian series. in the black base of greenstone are angular and roundish pieces of gneiss, some white, others of a light flesh-colour, some without lamination, like granite, others with laminæ, which, by their various and often opposite directions, show that they have been scattered at random through the matrix. these imbedded pieces of gneiss measure from to about inches in diameter. _rocks altered by volcanic dikes._--after these remarks on the form and composition of dikes themselves, i shall describe the alterations which they sometimes produce in the rocks in contact with them. the changes are usually such as the intense heat of melted matter and the entangled gases might be expected to cause. _plas-newydd._--a striking example, near plas-newydd, in anglesea, has been described by professor henslow.[ -a] the dike is feet wide, and consists of a rock which is a compound of felspar and augite (dolerite of some authors). strata of shale and argillaceous limestone, through which it cuts perpendicularly, are altered to a distance of , or even, in some places, to feet from the edge of the dike. the shale, as it approaches the trap, becomes gradually more compact, and is most indurated where nearest the junction. here it loses part of its schistose structure, but the separation into parallel layers is still discernible. in several places the shale is converted into hard porcellanous jasper. in the most hardened part of the mass the fossil shells, principally _producti_, are nearly obliterated; yet even here their impressions may frequently be traced. the argillaceous limestone undergoes analogous mutations, losing its earthy texture as it approaches the dike, and becoming granular and crystalline. but the most extraordinary phenomenon is the appearance in the shale of numerous crystals of analcime and garnet, which are distinctly confined to those portions of the rock affected by the dike.[ -a] some garnets contain as much as per cent. of lime, which they may have derived from the decomposition of the fossil shells or producti. the same mineral has been observed, under very analogous circumstances, in high teesdale, by professor sedgwick, where it also occurs in shale and limestone, altered by basalt.[ -b] _antrim._--in several parts of the county of antrim, in the north of ireland, chalk with flints is traversed by basaltic dikes. the chalk is there converted into granular marble near the basalt, the change sometimes extending or feet from the wall of the dike, being greatest near the point of contact, and thence gradually decreasing till it becomes evanescent. "the extreme effect," says dr. berger, "presents a dark brown crystalline limestone, the crystals running in flakes as large as those of coarse primitive (_metamorphic_) limestone; the next state is saccharine, then fine grained and arenaceous; a compact variety, having a porcellanous aspect and a bluish-grey colour, succeeds: this, towards the outer edge, becomes yellowish-white, and insensibly graduates into the unaltered chalk. the flints in the altered chalk usually assume a grey yellowish colour."[ -c] all traces of organic remains are effaced in that part of the limestone which is most crystalline. [illustration: fig. . basaltic dikes in chalk in island of rathlin, antrim. ground plan, as seen on the beach. (conybeare and buckland.[ -d])] the annexed drawing (fig. .) represents three basaltic dikes traversing the chalk, all within the distance of feet. the chalk contiguous to the two outer dikes is converted into a finely granular marble, _m m_, as are the whole of the masses between the outer dikes and the central one. the entire contrast in the composition and colour of the intrusive and invaded rocks, in these cases, renders the phenomena peculiarly clear and interesting. another of the dikes of the north-east of ireland has converted a mass of red sandstone into hornstone.[ -e] by another, the slate clay of the coal measures has been indurated, and has assumed the character of flinty slate[ -a]; and in another place the slate clay of the lias has been changed into flinty slate, which still retains numerous impressions of ammonites.[ -b] it might have been anticipated that beds of coal would, from their combustible nature, be effected in an extraordinary degree by the contact of melted rock. accordingly, one of the greenstone dikes of antrim, on passing through a bed of coal, reduces it to a cinder for the space of feet on each side.[ -c] at cockfield fell, in the north of england, a similar change is observed. specimens taken at the distance of about yards from the trap are not distinguishable from ordinary pit coal; those nearer the dike are like cinders, and have all the character of coke; while those close to it are converted into a substance resembling soot.[ -d] as examples might be multiplied without end, i shall merely select one or two others, and then conclude. the rock of stirling castle is a calcareous sandstone, fractured and forcibly displaced by a mass of greenstone which has evidently invaded the strata in a melted state. the sandstone has been indurated, and has assumed a texture approaching to hornstone near the junction. in arthur's seat and salisbury craig, near edinburgh, a sandstone which comes in contact with greenstone is converted into a jaspideous rock.[ -e] the secondary sandstones in skye are converted into solid quartz in several places, where they come in contact with veins or masses of trap; and a bed of quartz, says dr. macculloch, found near a mass of trap, among the coal strata of fife, was in all probability a stratum of ordinary sandstone, having been subsequently indurated and turned into quartzite by the action of heat.[ -f] but although strata in the neighbourhood of dikes are thus altered in a variety of cases, shale being turned into flinty slate or jasper, limestone into crystalline marble, sandstone into quartz, coal into coke, and the fossil remains of all such strata wholly and in part obliterated, it is by no means uncommon to meet with the same rocks, even in the same districts, absolutely unchanged in the proximity of volcanic dikes. this great inequality in the effects of the igneous rocks may often arise from an original difference in their temperature, and in that of the entangled gases, such as is ascertained to prevail in different lavas, or in the same lava near its source and at a distance from it. the power also of the invaded rocks to conduct heat may vary, according to their composition, structure, and the fractures which they may have experienced, and perhaps, also, according to the quantity of water (so capable of being heated) which they contain. it must happen in some cases that the component materials are mixed in such proportions as prepare them readily to enter into chemical union, and form new minerals; while in other cases the mass may be more homogeneous, or the proportions less adapted for such union. we must also take into consideration, that one fissure may be simply filled with lava, which may begin to cool from the first; whereas in other cases the fissure may give passage to a current of melted matter, which may ascend for days or months, feeding streams which are overflowing the country above, or are ejected in the shape of scoriæ from some crater. if the walls of a rent, moreover, are heated by hot vapour before the lava rises, as we know may happen on the flanks of a volcano, the additional caloric supplied by the dike and its gases will act more powerfully. [illustration: fig. . trap interposed between displaced beds of limestone and shale, at white force, high teesdale, durham. (sedgwick.[ -a])] _intrusion of trap between strata._--in proof of the mechanical force which the fluid trap has sometimes exerted on the rocks into which it has intruded itself, i may refer to the whin-sill, where a mass of basalt, from to feet in height, represented by _a_, fig. ., is in part wedged in between the rocks of limestone, _b_, and shale, _c_, which have been separated from the great mass of limestone and shale, _d_, with which they were united. the shale in this place is indurated; and the limestone, which at a distance from the trap is blue, and contains fossil corals, is here converted into granular marble without fossils. masses of trap are not unfrequently met with intercalated between strata, and maintaining their parallelism to the planes of stratification throughout large areas. they must in some places have forced their way laterally between the divisions of the strata, a direction in which there would be the least resistance to an advancing fluid, if no vertical rents communicated with the surface, and a powerful hydrostatic pressure was caused by gases propelling the lava upwards. _columnar and globular structure._--one of the characteristic forms of volcanic rocks, especially of basalt, is the columnar, where large masses are divided into regular prisms, sometimes easily separable, but in other cases adhering firmly together. the columns vary in the number of angles, from three to twelve; but they have most commonly from five to seven sides. they are often divided transversely, at nearly equal distances, like the joints in a vertebral column, as in the giant's causeway, in ireland. they vary exceedingly in respect to length and diameter. dr. macculloch mentions some in skye which are about feet long; others, in morven, not exceeding an inch. in regard to diameter, those of ailsa measure feet, and those of morven an inch or less.[ -a] they are usually straight, but sometimes curved; and examples of both these occur in the island of staffa. in a horizontal bed or sheet of trap the columns are vertical; in a vertical dike they are horizontal. among other examples of the last-mentioned phenomenon is the mass of basalt, called the chimney, in st. helena (see fig. .), a pile of hexagonal prisms, feet high, evidently the remainder of a narrow dike, the walls of rock which the dike originally traversed having been removed down to the level of the sea. in fig. . a small portion of this dike is represented on a less reduced scale.[ -b] [illustration: fig. . volcanic dike composed of horizontal prisms. st. helena.] [illustration: fig. . small portion of the dyke in fig. .] [illustration: fig. . lava of la coupe d'ayzac, near antraigue, in the province of ardèche.] it being assumed that columnar trap has consolidated from a fluid state, the prisms are said to be always at right angles to the _cooling surfaces_. if these surfaces, therefore, instead of being either perpendicular, or horizontal, are curved, the columns ought to be inclined at every angle to the horizon; and there is a beautiful exemplification of this phenomenon in one of the valleys of the vivarais, a mountainous district in the south of france, where, in the midst of a region of gneiss, a geologist encounters unexpectedly several volcanic cones of loose sand and scoriæ. from the crater of one of these cones called la coupe d'ayzac, a stream of lava descends and occupies the bottom of a narrow valley, except at those points where the river volant, or the torrents which join it, have cut away portions of the solid lava. the accompanying sketch (fig. .) represents the remnant of the lava at one of the points where a lateral torrent joins the main valley of the volant. it is clear that the lava once filled the whole valley up to the dotted line _d a_; but the river has gradually swept away all below that line, while the tributary torrent has laid open a transverse section; by which we perceive, in the first place, that the lava is composed, as usual in this country, of three parts: the uppermost, at _a_, being scoriaceous; the second, _b_, presenting irregular prisms; and the third, _c_, with regular columns, which are vertical on the banks of the volant, where they rest on a horizontal base of gneiss, but which are inclined at an angle of ° at _g_, and then horizontal at _f_, their position having been every where determined, according to the law before mentioned, by the concave form of the original valley. [illustration: fig . columnar basalt in the vicentin. (fortis.)] in the annexed figure ( .) a view is given of some of the inclined and curved columns which present themselves on the sides of the valleys in the hilly region north of vicenza, in italy, and at the foot of the higher alps.[ -a] unlike those of the vivarais, last mentioned, the basalt of this country was evidently submarine, and the present valleys have since been hollowed out by denudation. the columnar structure is by no means peculiar to the trap rocks in which hornblende or augite predominate; it is also observed in clinkstone, trachyte, and other felspathic rocks of the igneous class, although in these it is rarely exhibited in such regular polygonal forms. [illustration: fig. . basaltic pillars of the käsegrotte, bertrich-baden, half way between treves and coblentz. height of grotto, from to feet.] it has been already stated that basaltic columns are often divided by cross joints. sometimes each segment, instead of an angular, assumes a spheroidal form, so that a pillar is made up of a pile of balls, usually flattened, as in the cheese-grotto at bertrich-baden, in the eifel, near the moselle (fig. .). the basalt, there, is part of a small stream of lava, from to feet thick, which has proceeded from one of several volcanic craters, still extant, on the neighbouring heights. the position of the lava bordering the river in this valley might be represented by a section like that already given at fig. . p. ., if we merely supposed inclined strata of slate and the argillaceous sandstone called greywacké to be substituted for gneiss. in some masses of decomposing greenstone, basalt, and other trap rocks, the globular structure is so conspicuous that the rock has the appearance of a heap of large cannon balls. [illustration: fig. . globiform pitchstone. chiaja di luna, isle of ponza. (scrope.)] a striking example of this structure occurs in a resinous trachyte or pitchstone-porphyry in one of the ponza islands, which rise from the mediterranean, off the coast of terracina and gaeta. the globes vary from a few inches to three feet in diameter, and are of an ellipsoidal form (see fig. .). the whole rock is in a state of decomposition, "and when the balls," says mr. scrope, "have been exposed a short time to the weather, they scale off at a touch into numerous concentric coats, like those of a bulbous root, inclosing a compact nucleus. the laminæ of this nucleus have not been so much loosened by decomposition; but the application of a ruder blow will produce a still further exfoliation."[ -a] a fissile texture is occasionally assumed by clinkstone and other trap rocks, so that they have been used for roofing houses. sometimes the prismatic and slaty structure is found in the same mass. the causes which give rise to such arrangements are very obscure, but are supposed to be connected with changes of temperature during the cooling of the mass, as will be pointed out in the sequel. (see chaps. xxxv. and xxxvi.) _relation of trappean rocks to the products of active volcanos._ when we reflect on the changes above described in the strata near their contact with trap dikes, and consider how great is the analogy in composition and structure of the rocks called trappean and the lavas of active volcanos, it seems difficult at first to understand how so much doubt could have prevailed for half a century as to whether trap was of igneous or aqueous origin. to a certain extent, however, there was a real distinction between the trappean formations and those to which the term volcanic was almost exclusively confined. the trappean rocks first studied in the north of germany, and in norway, france, scotland, and other countries, were either such as had been formed entirely under deep water, or had been injected into fissures and intruded between strata, and which had never flowed out in the air, or over the bottom of a shallow sea. when these products, therefore, of submarine or subterranean igneous action were contrasted with loose cones of scoriæ, tuff, and lava, or with narrow streams of lava in great part scoriaceous and porous, such as were observed to have proceeded from vesuvius and etna, the resemblance seemed remote and equivocal. it was, in truth, like comparing the roots of a tree with its leaves and branches, which, although they belong to the same plant, differ in form, texture, colour, mode of growth, and position. the external cone, with its loose ashes and porous lava, may be likened to the light foliage and branches, and the rocks concealed far below, to the roots. but it is not enough to say of the volcano, "quantum vertice in auras Ætherias, tantum radice in tartara tendit," for its roots do literally reach downwards to tartarus, or to the regions of subterranean fire; and what is concealed far below, is probably always more important in volume and extent than what is visible above ground. [illustration: fig. . strata intersected by a trap dike, and covered with alluvium.] we have already stated how frequently dense masses of strata have been removed by denudation from wide areas (see chap. vi.); and this fact prepares us to expect a similar destruction of whatever may once have formed the uppermost part of ancient submarine or subaerial volcanos, more especially as those superficial parts are always of the lightest and most perishable materials. the abrupt manner in which dikes of trap usually terminate at the surface (see fig. .), and the water-worn pebbles of trap in the alluvium which covers the dike, prove incontestably that whatever was uppermost in these formations has been swept away. it is easy, therefore, to conceive that what is gone in regions of trap may have corresponded to what is now visible in active volcanos. it will be seen in the following chapters, that in the earth's crust there are volcanic tuffs of all ages, containing marine shells, which bear witness to eruptions at many successive geological periods. these tuffs, and the associated trappean rocks, must not be compared to lava and scoriæ which had cooled in the open air. their counterparts must be sought in the products of modern submarine volcanic eruptions. if it be objected that we have no opportunity of studying these last, it may be answered, that subterranean movements have caused, almost everywhere in regions of active volcanos, great changes in the relative level of land and sea, in times comparatively modern, so as to expose to view the effects of volcanic operations at the bottom of the sea. thus, for example, the recent examination of the igneous rocks of sicily, especially those of the val di noto, has proved that all the more ordinary varieties of european trap have been there produced under the waters of the sea, at a modern period; that is to say, since the mediterranean has been inhabited by a great proportion of the existing species of testacea. these igneous rocks of the val di noto, and the more ancient trappean rocks of scotland and other countries, differ from subaerial volcanic formations in being more compact and heavy, and in forming sometimes extensive sheets of matter intercalated between marine strata, and sometimes stratified conglomerates, of which the rounded pebbles are all trap. they differ also in the absence of regular cones and craters, and in the want of conformity of the lava to the lowest levels of existing valleys. it is highly probable, however, that insular cones did exist in some parts of the val di noto: and that they were removed by the waves, in the same manner as the cone of graham island, in the mediterranean, was swept away in , and that of nyöe, off iceland, in .[ -a] all that would remain in such cases, after the bed of the sea has been upheaved and laid dry, would be dikes and shapeless masses of igneous rock, cutting through sheets of lava which may have spread over the level bottom of the sea, and strata of tuff, formed of materials first scattered far and wide by the winds and waves, and then deposited. trap conglomerates also, to which the action of the waves must give rise during the denudation of such volcanic islands, will emerge from the deep whenever the bottom of the sea becomes land. the proportion of volcanic matter which is originally submarine must always be very great, as those volcanic vents which are not entirely beneath the sea, are almost all of them in islands, or, if on continents, near the shore. this may explain why extended sheets of trap so often occur, instead of narrow threads, like lava streams. for, a multitude of causes tend, near the land, to reduce the bottom of the sea to a nearly uniform level,--the sediment of rivers,--materials transported by the waves and currents of the sea from wasting cliffs,--showers of sand and scoriæ ejected by volcanos, and scattered by the wind and waves. when, therefore, lava is poured out on such a surface, it will spread far and wide in every direction in a liquid sheet, which may afterwards, when raised up, form the tabular capping of the land. as to the absence of porosity in the trappean formations, the appearances are in a great degree deceptive, for all amygdaloids are, as already explained, porous rocks, into the cells of which mineral matter, such as silex, carbonate of lime, and other ingredients, have been subsequently introduced (see p. .); sometimes, perhaps, by secretion during the cooling and consolidation of lavas. in the little cumbray, one of the western islands, near arran, the amygdaloid sometimes contains elongated cavities filled with brown spar; and when the nodules have been washed out, the interior of the cavities is glazed with the vitreous varnish so characteristic of the pores of slaggy lavas. even in some parts of this rock which are excluded from air and water, the cells are empty, and seem to have always remained in this state, and are therefore undistinguishable from some modern lavas.[ -a] dr. macculloch, after examining with great attention these and the other igneous rocks of scotland, observes, "that it is a mere dispute about terms, to refuse to the ancient eruptions of trap the name of submarine volcanos; for they are such in every essential point, although they no longer eject fire and smoke."[ -b] the same author also considers it not improbable that some of the volcanic rocks of the same country may have been poured out in the open air.[ -c] although the principal component minerals of subaerial lavas are the same as those of intrusive trap, and both the columnar and globular structure are common to both, there are, nevertheless, some volcanic rocks which never occur as lava, such as greenstone, clinkstone, the more crystalline porphyries, and those traps in which quartz and mica appear as constituent parts. in short, the intrusive trap rocks, forming the intermediate step between lava and the plutonic rocks, depart in their characters from lava in proportion as they approximate to granite. these views respecting the relations of the volcanic and trap rocks will be better understood when the reader has studied, in the d chapter, what is said of the plutonic formations. form, structure, and origin of volcanic mountains. the origin of volcanic cones with crater-shaped summits has been alluded to in the last chapter (p. .), and more fully explained in the "principles of geology" (chaps. xxiv. to xxvii.), where vesuvius, etna, santorin, and barren island were described. the more ancient portions of those mountains or islands, formed long before the times of history, exhibit the same external features and internal structure which belong to most of the extinct volcanos of still higher antiquity. the island of palma, for example, one of the canaries, offers an excellent illustration of what, in common with many others, i regard as the ruins of a large dome-shaped mass formed by a series of eruptions proceeding from a crater at the summit, this crater having been since replaced by a larger cavity, the origin of which has afforded geologists an ample field for discussion and speculation. [illustration: fig. . view of the isle of palma, and of the entrance into the central cavity or caldera. from von buch's "canary islands."] [illustration: fig. . map of the caldera of palma and the great ravine, called "barranco de las angustias." from survey of capt. vidal, r.n., .] von buch, in his excellent account of the canaries, has given us a graphic picture of this island, which consists chiefly of a single mountain (fig. .). this mountain has the general form of a great truncated cone, with a huge and deep cavity in the middle, about six miles in diameter, called by the inhabitants "the caldera," or cauldron. the range of precipices surrounding the caldera are no less than feet in their average height; at one point, where they are highest, they are feet above the level of the sea. the external flanks of the cone incline gently in every direction towards the base of the island, and are in part cultivated; but the walls and bottom of the caldera present on all sides rugged and uncultivated rocks, almost completely devoid of vegetation. so steep are these walls, that there is no part by which they can be descended, and the only entrance is by a great ravine, or barranco, as it is called (see _b b'_, map, fig. .), which extends from the sea to the interior of the great cavity, and by its jagged, broken, and precipitous sides, exhibits to the geologist a transverse section of the rocks of which the whole mountain is composed. by this means, we learn that the cone is made up of a great number of sloping beds, which dip outwards in every direction from the centre of the void space, or from the hollow axis of the cone. the beds consist chiefly of sheets of basalt, alternating with conglomerates; the materials of the latter being in part rounded, as if rolled by water in motion. the inclination of all the beds corresponds to that of the external slope of the island, being greatest towards the caldera, and least steep when they are nearest the sea. there are a great number of tortuous veins, and many dikes of lava or trap, chiefly basaltic, and most of them vertical, which cut through the sloping beds laid open to view in the great gorge or barranco. these dikes and veins are more and more abundant as we approach the caldera, being therefore most numerous where the slope of the beds is greatest. assuming the cone to be a pile of volcanic materials ejected by a long succession of eruptions (a point on which all geologists are agreed), we have to account for the caldera and the great barranco. i conceive that the cone itself may be explained, in accordance with what we know of the ordinary growth of volcanos[ -a], by supposing most of the eruptions to have taken place from one or more central vents, at or near the summit of the cone, before it was truncated. from this culminating point, sheets of lava flowed down one after the other, and showers of ashes or ejected stones. the volcano may, in the earlier stages of its growth, have been in great part submerged, like stromboli, in the sea; and, therefore, some of the fragments of rock cast out of its crater may not only have been rolled by torrents sweeping down the mountain's side, but have also been rounded by the waves of the sea, as we see happen on the beach near catania, on which the modern lavas of etna are broken up. the increased number of dykes, as we approach the axis of the cone, agrees well with the hypothesis of the eruptions having been most frequent towards the centre. there are three known causes or modes of operation, which may have conduced towards the vast size of the caldera. first, the summit of a conical mountain may have fallen in, as happened in the case of capacurcu, one of the andes, according to tradition, in the year , and of many other volcanic mountains.[ -a] sections seem wanting, to supply us with all the data required for judging fairly of the tenability of this hypothesis. it appears, however, from captain vidal's survey (see fig. .), that a hill of considerable height rises up from the bottom of the caldera, the structure of which, if it be any where laid open, might doubtless throw much light on this subject. secondly, an original crater may have been enlarged by a vast gaseous explosion, never followed by any subsequent eruption. a serious objection to this theory arises from our not finding that the exterior of the cone supports a mass of ruins, such as ought to cover it, had so enormous a volume of matter, partly made up of the solid contents of the dikes, been blown out into the air. in that case, an extensive bed of angular fragments of stone, and of fine dust, might be looked for, enveloping the entire exterior of the mountain up to the very rim of the caldera, and ought nowhere to be intersected by a dike. the absence of such a formation has induced von buch to suppose that the missing portion of the cone was engulphed. it should, however, be remembered, that in existing volcanos, large craters, two or three miles in diameter, are sometimes formed by explosions, or by the discharge of great volumes of steam. there is yet another cause to which the extraordinary dimensions of the caldera may, in part at least, be owing; namely, aqueous denudation. von buch has observed, that the existence of a single deep ravine, like the great barranco, is a phenomenon common to many extinct volcanos, as well as to some active ones. now, it will be seen by captain vidal's map (fig. . p. .), that the sea-cliff at point juan graje, feet high, now constituting the coast at the entrance of the great ravine, is continuous with an inland cliff which bounds the same ravine on its north-western side. no one will dispute that the precipice, at the base of which the waves are now beating, owes its origin to the undermining power of the sea. it is natural, therefore, to attribute the extension of the same cliff to the former action of the waves, exerted at a time when the relative level of the island and the ocean were different from what they are now. but if the waves and tides had power to remove the rocks once filling a great gorge which is miles long, and, in its upper part, feet deep, can we doubt that the same power may have cleared out much of the solid mass now missing in the great caldera? the theory advanced to account for the configuration of palma, commonly called the "elevation crater theory," is this. all the alternating masses of basalt and conglomerate, intersected in the barranco, or abruptly cut off in the escarpment or walls of the caldera, were at first disposed in horizontal masses on the level floor of the ocean, and traversed, when in that position, by all the basaltic dikes which now cut through them. at length they were suddenly uplifted by the explosive force of elastic vapours, which raised the mass bodily, so as to tilt the beds on all sides away from the centre of elevation, causing at the same time an opening at the culminating point. besides many other objections which may be urged against this hypothesis, it leaves unexplained the unbroken continuity of the rim of the caldera, which is uninterrupted in all places save one[ -a], namely, that where the great gorge or barranco occurs. as a more natural way of explaining the phenomenon, the following series of events may be imagined. the principal vent, from which a large part of the materials of the cone were poured or thrown out, was left empty after the last escape of vapour, when the volcano became extinct. we learn from mr. dana's valuable work on the geology of the united states' exploring expedition, published in , that two of the principal volcanos of the sandwich islands, mounts loa and kea in owyhee, are huge flattened volcanic cones, , feet high (see fig. .), each equalling two and a half etnas in their dimensions. [illustration: fig. . mount loa, in the sandwich islands. (dana) _a._ crater at the summit. _b._ the lateral crater of kilauea. the dotted lines indicate a supposed column of solid rock caused by the lava consolidating after eruptions.] from the summits of these lofty though featureless hills, and from vents not far below their summits, successive streams of lava, often miles or more in width, and sometimes miles long, have flowed. they have been poured out one after the other, some of them in recent times, in every direction from the apex of the cone, down slopes varying on an average from degrees to degrees; but at some places considerably steeper.[ -b] sometimes deep rents open on the sides of these cones, which are filled by streams of lava passing over them, the liquid matter in such cases probably uniting in the fissure with other lava melted in subterranean reservoirs below, and thus explaining the origin of one great class of lateral dikes, on etna, palma, and other cones. if the flattened domes, such as those here alluded to in the sandwich islands, instead of being inland, and above water, were situated in mid-ocean, like the island of st. paul, and for the most part submerged (see figs. , , .), and if a gradual upheaval of such a dome should then take place, the denuding power of the sea could scarcely fail to play an important part in modifying the form of the volcanic mountain as it rose. the crater will almost invariably have one side much lower than all the others, namely, that side towards which the prevailing winds never blow, and to which, therefore, showers of dust and scoriæ are rarely carried during eruptions. there will also be one point on this windward or lowest side more depressed than all the rest, by which the sea may enter as often as the tide rises, or as often as the wind blows from that quarter. for the same reason that the sea continues to keep open a single entrance into the lagoon of an atoll or annular coral reef, it will not allow this passage into the crater to be stopped up, but scour it out, at low tide, or as often as the wind changes. the channel, therefore, will always be deepened in proportion as the island rises above the level of the sea, at the rate perhaps of a few feet or yards in a century. [illustration: fig. . map of the island of st. paul, in the indian ocean, lat. ° ´ s., long. ° ´ e., surveyed by capt. blackwood, r.n., .] [illustration: fig. . view of the crater of the island of st. paul.] the island of st. paul may perhaps be motionless; but if, like many other parts of the earth's crust, it should begin to undergo a gradual upheaval, or if, as has happened to the shores of the bay of baiæ, its level should oscillate, with a tendency upon the whole to increased elevation, the same power which has cut away part of the cone, and caused the cliffs now seen on the north-east side of the island, would have power to undermine the walls of the crater, and enlarge its diameter, keeping open the channel, by which it enters into it. this ravine might be excavated to the depth of feet (the present depth of the crater), and its length might be extended to many miles according to the size of the submerged part of the cone. the crater is only a mile in diameter, and the surrounding cliffs, where loftiest, only feet high, so that the size of this cone and crater is insignificant when compared to those in the sandwich islands, and i have merely selected it because it affords an example of a class of insular volcanos, into the craters of which the sea now enters by a single passage. the crater of vesuvius in was feet deep; and if it were a half submerged cone, like st. paul, the excavating power of the ocean might in conjunction with gaseous explosions and co-operating with a gradual upheaving force, give rise to a caldera on as grand a scale as that exhibited by palma. [illustration: fig. . side view of the island of st. paul (n.e. side). nine-pin rocks two miles distant. (captain blackwood.)] if, after the geographical changes above supposed, the volcanic fires long dormant should recover their energy, they might, as in the case of teneriffe, vesuvius, santorin, and barren island, discharge from the old central vent, long sealed up at the bottom of the caldera, new floods of lava and clouds of elastic vapours. should this happen, a new cone will be built up in the middle of the cavity or circular bay, formed, partly by explosion, partly perhaps by engulphment, and partly by aqueous denudation. in the island of palma this last phase of volcanic activity has never occurred; but the subterranean heat is still in full operation beneath the canary islands, so that we know not what future changes it may be destined to undergo. footnotes: [ -a] i have been favoured with this drawing by captain b. hall. [ -a] cambridge transactions, vol. i. p. . [ -a] cambridge trans., vol. i. p. . [ -b] ibid. vol. ii. p. . [ -c] dr. berger, geol. trans., st series, vol. iii. p. . [ -d] geol. trans., st series, vol. iii. p. . and plate . [ -e] ibid. p. . [ -a] geol. trans., st series, vol. iii. p. . [ -b] ibid. p. .; and playfair, illust. of hutt. theory, p. . [ -c] geol. trans., st series, vol. iii. p. . [ -d] sedgwick, camb. trans. vol. ii. p. . [ -e] illust. of hutt. theory, § . and . dr. macculloch, geol. trans., st series, vol. ii. p. . [ -f] syst. of geol. vol. i. p. . [ -a] camb. trans. vol. ii. p. . [ -a] maccul. syst. of geol. vol. ii. p. . [ -b] seale's geognosy of st. helena, plate . [ -a] fortis. mém. sur l'hist. nat. de l'italie, tom. i. p. . plate . [ -a] scrope, geol. trans. vol. ii. p. . d series. [ -a] see princ. of geol., _index_, "graham island," "nyöe," "conglomerates, volcanic," &c. [ -a] macculloch, west. isl., vol. ii. p. . [ -b] syst. of geol., vol. ii. p. . [ -c] ibid. [ -a] see principles, chaps. xxiv-xxvii. [ -a] see principles, chaps. xxvi. and xxx.; th ed. p. - . [ -a] see principles of geol. ch. xxiv. ( th ed. p. .). [ -b] see lyell on craters of denudation, quart. geol. journ. vol. vi. p. . chapter xxx. on the different ages of the volcanic rocks. tests of relative age of volcanic rocks--test by superposition and intrusion--dike of quarrington hill, durham--test by alteration of rocks in contact--test by organic remains--test of age by mineral character--test by included fragments--volcanic rocks of the post-pliocene period--basalt of bay of trezza in sicily--post-pliocene volcanic rocks near naples--dikes of somma--igneous formations of the newer pliocene period--val di noto in sicily. having referred the sedimentary strata to a long succession of geological periods, we have next to consider how far the volcanic formations can be classed in a similar chronological order. the tests of relative age in this class of rocks are four:-- st, superposition and intrusion, with or without alteration of the rocks in contact; d, organic remains; d, mineral character; th, included fragments of older rocks. [illustration: fig. . cross section.] _tests by superposition, &c._--if a volcanic rock rests upon an aqueous deposit, the former must be the newest of the two, but the like rule does not hold good where the aqueous formation rests upon the volcanic, for melted matter, rising from below, may penetrate a sedimentary mass without reaching the surface, or may be forced in conformably between two strata, as _b_ at d in the annexed figure (fig. .), after which it may cool down and consolidate. superposition, therefore, is not of the same value as a test of age in the unstratified volcanic rocks as in fossiliferous formations. we can only rely implicitly on this test where the volcanic rocks are contemporaneous, not where they are intrusive. now they are said to be contemporaneous if produced by volcanic action, which was going on simultaneously with the deposition of the strata with which they are associated. thus in the section at d (fig. .), we may perhaps ascertain that the trap _b_ flowed over the fossiliferous bed _c_, and that, after its consolidation, _a_ was deposited upon it, _a_ and _c_ both belonging to the same geological period. but if the stratum _a_ be altered by _b_ at the point of contact, we must then conclude the trap to have been intrusive, or if, in pursuing _b_ for some distance, we find at length that it cuts through the stratum _a_, and then overlies it as at e. we may, however, be easily deceived in supposing a volcanic rock to be intrusive, when in reality it is contemporaneous; for a sheet of lava, as it spreads over the bottom of the sea, cannot rest everywhere upon the same stratum, either because these have been denuded, or because, if newly thrown down, they thin out in certain places, thus allowing the lava to cross their edges. besides, the heavy igneous fluid will often, as it moves along, cut a channel into beds of soft mud and sand. suppose the submarine lava f to have come in contact in this manner with the strata _a_, _b_, _c_, and that after its consolidation, the strata _d_, _e_, are thrown down in a nearly horizontal position, yet so as to lie unconformably to f, the appearance of subsequent intrusion will here be complete, although the trap is in fact contemporaneous. we must not, therefore, hastily infer that the rock f is intrusive, unless we find the strata _d_ or _e_ to have been altered at their junction, as if by heat. [illustration: fig. . cross section.] when trap dikes were described in the preceding chapter, they were shown to be more modern than all the strata which they traverse. a basaltic dike at quarrington hill, near durham, passes through coal-measures, the strata of which are inclined, and shifted so that those on the north side of the dike are feet above the level of the corresponding beds on the south side (see section, fig. .). but the horizontal beds of overlying red sandstone and magnesian limestone are not cut through by the dike. now here the coal-measures were not only deposited, but had subsequently been disturbed, fissured, and shifted, before the fluid trap now forming the dike was introduced into a rent. it is also clear that some of the upper edges of the coal strata, together with the upper part of the dike, had been subsequently removed by denudation before the lower new red sandstone and magnesian limestone were superimposed. even in this case, however, although the date of the volcanic eruption is brought within narrow limits, it cannot be defined with precision; it may have happened either at the close of the carboniferous period, or early in that of the lower new red sandstone, or between these two periods, when the state of the animate creation and the physical geography of europe were gradually changing from the type of the carboniferous era to that of the permian. [illustration: fig. . section at quarrington hill, east of durham. (sedgwick.) _a._ magnesian limestone (permian). _b._ lower new red sandstone. _c._ coal strata.] the test of age by superposition is strictly applicable to all stratified volcanic tuffs, according to the rules already explained in the case of other sedimentary deposits. (see p. .) _test of age by organic remains._--we have seen how, in the vicinity of active volcanos, scoriæ, pumice, fine sand, and fragments of rock are thrown up into the air, and then showered down upon the land, or into neighbouring lakes or seas. in the tuffs so formed shells, corals, or any other durable organic bodies which may happen to be strewed over the bottom of a lake or sea will be imbedded, and thus continue as permanent memorials of the geological period when the volcanic eruption occurred. tufaceous strata thus formed in the neighbourhood of vesuvius, etna, stromboli, and other volcanos now active in islands or near the sea, may give information of the relative age of these tuffs at some remote future period when the fires of these mountains are extinguished. by such evidence we can distinctly establish the coincidence in age of volcanic rocks, and the different primary, secondary, and tertiary fossiliferous strata already considered. the tuffs now alluded to are not exclusively marine, but include, in some places, freshwater shells; in others, the bones of terrestrial quadrupeds. the diversity of organic remains in formations of this nature is perfectly intelligible, if we reflect on the wide dispersion of ejected matter during late eruptions, such as that of the volcano of coseguina, in the province of nicaragua, january . . hot cinders and fine scoriæ were then cast up to a vast height, and covered the ground as they fell to the depth of more than feet, and for a distance of leagues from the crater in a southerly direction. birds, cattle, and wild animals were scorched to death in great numbers, and buried in these ashes. some volcanic dust fell at chiapa, upwards of miles to windward of the volcano, a striking proof of a counter current in the upper region of the atmosphere; and some on jamaica, about miles distant to the north-east. in the sea, also, at the distance of miles from the point of eruption, captain eden of the conway sailed miles through floating pumice, among which were some pieces of considerable size.[ -a] _test of age by mineral composition._--as sediment of homogeneous composition, when discharged from the mouth of a large river, is often deposited simultaneously over a wide space, so a particular kind of lava, flowing from a crater during one eruption, may spread over an extensive area; as in iceland in , when the melted matter, pouring from skaptar jokul, flowed in streams in opposite directions, and caused a continuous mass, the extreme points of which were miles distant from each other. this enormous current of lava varied in thickness from feet to feet, and in breadth from that of a narrow river gorge to miles.[ -b] now, if such a mass should afterwards be divided into separate fragments by denudation, we might still perhaps identify the detached portions by their similarity in mineral composition. nevertheless, this test will not always avail the geologist; for, although there is usually a prevailing character in lava emitted during the same eruption, and even in the successive currents flowing from the same volcano, still, in many cases, the different parts even of one lava-stream, or, as before stated, of one continuous mass of trap, vary so much in mineral composition and texture as to render these characters of minor importance when compared to their value in the chronology of the fossiliferous rocks. it will, however, be seen in the description which follows, of the european trap rocks of different ages, that they had often a peculiar lithological character, resembling the differences before remarked as existing between the modern lavas of vesuvius, etna, and chili. (see p. .) it has been remarked that in auvergne, the eifel, and other countries where trachyte and basalt are both present, the trachytic rocks are for the most part older than the basaltic. these rocks do, indeed, sometimes alternate partially, as in the volcano of mont dor, in auvergne; but the great mass of trachyte occupies in general an inferior position, and is cut through and overflowed by basalt. it can by no means be inferred that trachyte predominated greatly at one period of the earth's history and basalt at another, for we know that trachytic lavas have been formed at many successive periods, and are still emitted from many active craters; but it seems that in each region, where a long series of eruptions have occurred, the more felspathic lavas have been first emitted, and the escape of the more augitic kinds has followed. the hypothesis suggested by mr. scrope may, perhaps, afford a solution of this problem. the minerals, he observes, which abound in basalt are of greater specific gravity than those composing the felspathic lavas; thus, for example, hornblende, augite, and olivine are each more than three times the weight of water; whereas common felspar, albite, and labrador felspar, have each scarcely more than - / times the specific gravity of water; and the difference is increased in consequence of there being much more iron in a metallic state in basalt and greenstone than in trachyte and other felspathic lavas and traps. if, therefore, a large quantity of rock be melted up in the bowels of the earth by volcanic heat, the denser ingredients of the boiling fluid may sink to the bottom, and the lighter remaining above would in that case be first propelled upwards to the surface by the expansive power of gases. those materials, therefore, which occupied the lowest place in the subterranean reservoir will always be emitted last, and take the uppermost place on the exterior of the earth's crust. _test by included fragments._--we may sometimes discover the relative age of two trap rocks, or of an aqueous deposit and the trap on which it rests, by finding fragments of one included in the other, in cases such as those before alluded to, where the evidence of superposition alone would be insufficient. it is also not uncommon to find conglomerates almost exclusively composed of rolled pebbles of trap, associated with stratified rocks in the neighbourhood of masses of intrusive trap. if the pebbles agree generally in mineral character with the latter, we are then enabled to determine the age of the intrusive rock by knowing that of the fossiliferous strata associated with the conglomerate. the origin of such conglomerates is explained by observing the shingle beaches composed of trap pebbles in modern volcanic islands, or at the base of etna. _post-pliocene period (including the recent)._--i shall now select examples of contemporaneous volcanic rocks of successive geological periods, to show that igneous causes have been in activity in all past ages of the world, and that they have been ever shifting the places where they have broken out at the earth's surface. one portion of the lavas, tuffs, and trap dikes of etna, vesuvius, and the island of ischia, has been produced within the historical era; another, and a far more considerable part, originated at times immediately antecedent, when the waters of the mediterranean were already inhabited by the existing species of testacea. the southern and eastern flanks of etna are skirted by a fringe of alternating sedimentary and volcanic deposits, of submarine origin, as at adernò, trezza, and other places. of sixty-five species of fossil shells which i procured in from this formation, near trezza, it was impossible to distinguish any from species now living in the neighbouring sea. [illustration: fig. . view of the isle of cyclops in the bay of trezza.[ -a]] the cyclopian islands, called by the sicilians dei faraglioni, in the sea cliffs of which these beds of clay, tuff, and associated lava are laid open to view, are situated in the bay of trezza, and may be regarded as the extremity of a promontory severed from the main land. here numerous proofs are seen of submarine eruptions, by which the argillaceous and sandy strata were invaded and cut through, and tufaceous breccias formed. inclosed in these breccias are many angular and hardened fragments of laminated clay in different states of alteration by heat, and intermixed with volcanic sands. the loftiest of the cyclopian islets, or rather rocks, is about feet in height, the summit being formed of a mass of stratified clay, the laminæ of which are occasionally subdivided by thin arenaceous layers. these strata dip to the n.w., and rest on a mass of columnar lava (see fig. .) in which the tops of the pillars are weathered, and so rounded as to be often hemispherical. in some places in the adjoining and largest islet of the group, which lies to the north-eastward of that represented in the drawing (fig. .), the overlying clay has been greatly altered, and hardened by the igneous rock, and occasionally contorted in the most extraordinary manner; yet the lamination has not been obliterated, but, on the contrary, rendered much more conspicuous, by the indurating process. [illustration: fig. . contortions of strata in the largest of the cyclopian islands.] in the annexed woodcut (fig. .) i have represented a portion of the altered rock, a few feet square, where the alternating thin laminæ of sand and clay have put on the appearance which we often observe in some of the most contorted of the metamorphic schists. a great fissure, running from east to west, nearly divides this larger island into two parts, and lays open its internal structure. in the section thus exhibited, a dike of lava is seen, first cutting through an older mass of lava, and then penetrating the superincumbent tertiary strata. in one place the lava ramifies and terminates in thin veins, from a few feet to a few inches in thickness. (see fig. .) the arenaceous laminæ are much hardened at the point of contact, and the clays are converted into siliceous schist. in this island the altered rocks assume a honeycombed structure on their weathered surface, singularly contrasted with the smooth and even outline which the same beds present in their usual soft and yielding state. the pores of the lava are sometimes coated, or entirely filled, with carbonate of lime, and with a zeolite resembling analcime, which has been called cyclopite. the latter mineral has also been found in small fissures traversing the altered marl, showing that the same cause which introduced the minerals into the cavities of the lava, whether we suppose sublimation or aqueous infiltration, conveyed it also into the open rents of the contiguous sedimentary strata. [illustration: fig. . post-pliocene strata invaded by lava, isle of cyclops (horizontal section). _a._ lava. _b._ laminated clay and sand. _c._ the same altered.] _post-pliocene formations near naples._--i have traced in the "principles of geology" the history of the changes which the volcanic region of campania is known to have undergone during the last years. the aggregate effect of igneous operations during that period is far from insignificant, comprising as it does the formation of the modern cone of vesuvius since the year , and the production of several minor cones in ischia, together with that of monte nuovo in the year . lava-currents have also flowed upon the land and along the bottom of the sea--volcanic sand, pumice, and scoriæ have been showered down so abundantly, that whole cities were buried--tracts of the sea have been filled up or converted into shoals--and tufaceous sediment has been transported by rivers and land-floods to the sea. there are also proofs, during the same recent period, of a permanent alteration of the relative levels of the land and sea in several places, and of the same tract having, near puzzuoli, been alternately upheaved and depressed to the amount of more than feet. in connection with these convulsions, there are found, on the shores of the bay of baiæ, recent tufaceous strata, filled with articles fabricated by the hands of man, and mingled with marine shells. it was also stated in this work (p. .), that when we examine this same region, it is found to consist largely of tufaceous strata, of a date anterior to human history or tradition, which are of such thickness as to constitute hills from to more than feet in height. these post-pliocene strata, containing recent marine shells, alternate with distinct currents and sheets of lava which were of contemporaneous origin; and we find that in vesuvius itself, the ancient cone called somma is of far greater volume than the modern cone, and is intersected by a far greater number of dikes. in contrasting this ancient part of the mountain with that of modern date, one principal point of difference is observed; namely, the greater frequency in the older cone of fragments of altered sedimentary rocks ejected during eruptions. we may easily conceive that the first explosions would act with the greatest violence, rending and shattering whatever solid masses obstructed the escape of lava and the accompanying gases, so that great heaps of ejected pieces of rock would naturally occur in the tufaceous breccias formed by the earliest eruptions. but when a passage had once been opened, and an habitual vent established, the materials thrown out would consist of liquid lava, which would take the form of sand and scoriæ, or of angular fragments of such solid lavas as may have choked up the vent. among the fragments which abound in the tufaceous breccias of somma, none are more common than a saccharoid dolomite, supposed to have been derived from an ordinary limestone altered by heat and volcanic vapours. carbonate of lime enters into the composition of so many of the simple minerals found in somma, that m. mitscherlich, with much probability, ascribes their great variety to the action of the volcanic heat on subjacent masses of limestone. _dikes of somma._--the dikes seen in the great escarpment which somma presents towards the modern cone of vesuvius are very numerous. they are for the most part vertical, and traverse at right angles the beds of lava, scoriæ, volcanic breccia, and sand, of which the ancient cone is composed. they project in relief several inches, or sometimes feet, from the face of the cliff, being extremely compact, and less destructible than the intersected tuffs and porous lavas. in vertical extent they vary from a few yards to feet, and in breadth from to feet. many of them cut all the inclined beds in the escarpment of somma from top to bottom, others stop short before they ascend above half way, and a few terminate at both ends, either in a point or abruptly. in mineral composition they scarcely differ from the lavas of somma, the rock consisting of a base of leucite and augite, through which large crystals of augite and some of leucite are scattered.[ -a] examples are not rare of one dike cutting through another, and in one instance a shift or fault is seen at the point of intersection. in some cases, however, the rents seem to have been filled laterally, when the walls of the crater had been broken by star-shaped cracks, as seen in the accompanying woodcut (fig. .). but the shape of these rents is an exception to the general rule; for nothing is more remarkable than the usual parallelism of the opposite sides of the dikes, which correspond almost as regularly as the two opposite faces of a wall of masonry. this character appears at first the more inexplicable, when we consider how jagged and uneven are the rents caused by earthquakes in masses of heterogeneous composition, like those composing the cone of somma. in explanation of this phenomenon, m. necker refers us to sir w. hamilton's account of an eruption of vesuvius in the year , who records the following facts:--"the lavas, when they either boiled over the crater, or broke out from the conical parts of the volcano, constantly formed channels as regular as if they had been cut by art down the steep part of the mountain; and, whilst in a state of perfect fusion, continued their course in those channels, which were sometimes full to the brim, and at other times more or less so, according to the quantity of matter in motion. [illustration: fig. . dikes or veins at the punta del nasone on somma. (necker.[ -a])] "these channels, upon examination after an eruption, i have found to be in general from two to five or six feet wide, and seven or eight feet deep. they were often hid from the sight by a quantity of scoriæ that had formed a crust over them; and the lava, having been conveyed in a covered way for some yards, came out fresh again into an open channel. after an eruption, i have walked in some of those subterraneous or covered galleries, which were exceedingly curious, the sides, top, and bottom _being worn perfectly smooth and even_ in most parts, by the violence of the currents of the red-hot lavas which they had conveyed for many weeks successively."[ -b] now, the walls of a vertical fissure, through which lava has ascended in its way to a volcanic vent, must have been exposed to the same erosion as the sides of the channels before adverted to. the prolonged and uniform friction of the heavy fluid, as it is forced and made to flow upwards, cannot fail to wear and smooth down the surfaces on which it rubs, and the intense heat must melt all such masses as project and obstruct the passage of the incandescent fluid. the texture of the vesuvian dikes is different at the edges and in the middle. towards the centre, observes m. necker, the rock is larger grained, the component elements being in a far more crystalline state; while at the edge the lava is sometimes vitreous, and always finer grained. a thin parting band, approaching in its character to pitchstone, occasionally intervenes, on the contact of the vertical dike and intersected beds. m. necker mentions one of these at the place called primo monte, in the atrio del cavallo; and when on somma, in , i saw three or four others in different parts of the great escarpment. these phenomena are in perfect harmony with the results of the experiments of sir james hall and mr. gregory watt, which have shown that a glassy texture is the effect of sudden cooling, and that, on the contrary, a crystalline grain is produced where fused minerals are allowed to consolidate slowly and tranquilly under high pressure. it is evident that the central portion of the lava in a fissure would, during consolidation, part with its heat more slowly than the sides, although the contrast of circumstances would not be so great as when we compare the lava at the bottom and at the surface of a current flowing in the open air. in this case the uppermost part, where it has been in contact with the atmosphere, and where refrigeration has been most rapid, is always found to consist of scoriform, vitreous, and porous lava; while at a greater depth the mass assumes a more lithoidal structure, and then becomes more and more stony as we descend, until at length we are able to recognize with a magnifying glass the simple minerals of which the rock is composed. on penetrating still deeper, we can detect the constituent parts by the naked eye, and in the vesuvian currents distinct crystals of augite and leucite become apparent. the same phenomenon, observes m. necker, may readily be exhibited on a smaller scale, if we detach a piece of liquid lava from a moving current. the fragment cools instantly, and we find the surface covered with a vitreous coat; while the interior, although extremely fine-grained, has a more stony appearance. it must, however, be observed, that although the lateral portions of the dikes are finer grained than the central, yet the vitreous parting layer before alluded to is rare in vesuvius. this may, perhaps, be accounted for, as the above-mentioned author suggests, by the great heat which the walls of a fissure may acquire before the fluid mass begins to consolidate, in which case the lava, even at the sides, would cool very slowly. some fissures, also, may be filled from above, as frequently happens in the volcanos of the sandwich islands, according to the observations of mr. dana; and in this case the refrigeration at the sides would be more rapid than when the melted matter flowed upwards from the volcanic foci, in an intensely heated state. mr. darwin informs me that in st. helena almost every dike has a vitreous selvage. the rock composing the dikes both in the modern and ancient part of vesuvius is far more compact than that of ordinary lava, for the pressure of a column of melted matter in a fissure greatly exceeds that in an ordinary stream of lava; and pressure checks the expansion of those gases which give rise to vesicles in lava. there is a tendency in almost all the vesuvian dikes to divide into horizontal prisms, a phenomenon in accordance with the formation of vertical columns in horizontal beds of lava; for in both cases the divisions which give rise to the prismatic structure are at right angles to the cooling surfaces. _newer pliocene period--val di noto._--i have already alluded (see p. .) to the igneous rocks which are associated with a great marine formation of limestone, sand, and marl, in the southern part of sicily, as at vizzini and other places. in this formation, which was shown to belong to the newer pliocene period, large beds of oysters and corals repose upon lava, and are unaltered at the point of contact. in other places we find dikes of igneous rock intersecting the fossiliferous beds, and converting the clays into siliceous schist, the laminæ being contorted and shivered into innumerable fragments at the junction, as near the town of vizzini. the volcanic formations of the val di noto usually consist of the most ordinary variety of basalt, with or without olivine. the rock is sometimes compact, often very vesicular. the vesicles are occasionally empty, both in dikes and currents, and are in some localities filled with calcareous spar, arragonite, and zeolites. the structure is, in some places, spheroidal; in others, though rarely, columnar. i found dikes of amygdaloid, wacké, and prismatic basalt, intersecting the limestone at the bottom of the hollow called gozzo degli martiri, below melilli. [ illustrations: fig. . fig. . ground-plan of dikes near palagonia. _a._ lava. _b._ peperino, consisting of volcanic sand, mixed with fragments of lava and limestone.] _dikes._--dikes of vesicular and amygdaloidal lava are also seen traversing marine tuff or peperino, west of palagonia, some of the pores of the lava being empty, while others are filled with carbonate of lime. in such cases, we may suppose the peperino to have resulted from showers of volcanic sand and scoriæ, together with fragments of limestone, thrown out by a submarine explosion, similar to that which gave rise to graham island in . when the mass was, to a certain degree, consolidated, it may have been rent open, so that the lava ascended through fissures, the walls of which were perfectly even and parallel. after the melted matter that filled the rent in fig. . had cooled down, it must have been fractured and shifted horizontally by a lateral movement. in the second figure (fig. .), the lava has more the appearance of a vein which forced its way through the peperino. it is highly probable that similar appearances would be seen, if we could examine the floor of the sea in that part of the mediterranean where the waves have recently washed away the new volcanic island; for when a superincumbent mass of ejected fragments has been removed by denudation, we may expect to see sections of dikes traversing tuff, or, in other words, sections of the channels of communication by which the subterranean lavas reached the surface. footnotes: [ -a] caldcleugh, phil. trans. . p. ., and official documents of nicaragua. [ -b] see principles, _index_, "skaptar jokul." [ -a] this view of the isle of cyclops is from an original drawing by my friend the late captain basil hall, r. n. [ -a] consult the valuable memoir of m. l. a. necker, mém. de la soc. de phys. et d'hist. nat. de génève, tom. ii. part i. nov. . [ -a] from a drawing of m. necker, in mém. above cited. [ -b] phil. trans., vol. lxx., . chapter xxxi. on the different ages of the volcanic rocks--_continued_. volcanic rocks of the older pliocene period--tuscany--rome--volcanic region of olot in catalonia--cones and lava-currents--ravines and ancient gravel-beds--jets of air called bufadors--age of the catalonian volcanos--miocene period--brown-coal of the eifel and contemporaneous trachytic breccias--age of the brown-coal--peculiar characters of the volcanos of the upper and lower eifel--lake craters--trass--hungarian volcanos. _older pliocene period--tuscany._--in tuscany, as at radicofani, viterbo, and aquapendente, and in the campagna di roma, submarine volcanic tuffs are interstratified with the older pliocene strata of the subapennine hills, in such a manner as to leave no doubt that they were the products of eruptions which occurred when the shelly marls and sands of the subapennine hills were in the course of deposition. _catalonia._--geologists are far from being able, as yet, to assign to each of the volcanic groups scattered over europe a precise chronological place in the tertiary series; but i shall describe here, as probably referable to some part of the pliocene period, a district of extinct volcanos near olot, in the north of spain, which is little known, and which i visited in the summer of . the whole extent of country occupied by volcanic products in catalonia is not more than fifteen geographical miles from north to south, and about six from east to west. the vents of eruption range entirely within a narrow band running north and south; and the branches, which are represented as extending eastward in the map, are formed simply of two lava-streams--those of castell follit and cellent. [illustration: fig. . volcanic district of catalonia.] dr. maclure, the american geologist, was the first who made known the existence of these volcanos[ -a]; and, according to his description, the volcanic region extended over twenty square leagues, from amer to massanet. i searched in vain in the environs of massanet, in the pyrenees, for traces of a lava-current; and i can say, with confidence, that the adjoining map gives a correct view of the true area of the volcanic action. _geological structure of the district._--the eruptions have burst entirely through fossiliferous rocks, composed in great part of grey and greenish sandstone and conglomerate, with some thick beds of nummulitic limestone. the conglomerate contains pebbles of quartz, limestone, and lydian stone. this system of rocks is very extensively spread throughout catalonia; one of its members being a red sandstone, to which the celebrated salt-rock of cardona, usually considered as of the cretaceous era, is subordinate. near amer, in the valley of the ter, on the southern borders of the region delineated in the map, primary rocks are seen, consisting of gneiss, mica-schist, and clay-slate. they run in a line nearly parallel to the pyrenees, and throw off the fossiliferous strata from their flanks, causing them to dip to the north and north-west. this dip, which is towards the pyrenees, is connected with a distinct axis of elevation, and prevails through the whole area described in the map, the inclination of the beds being sometimes at an angle of between and degrees. it is evident that the physical geography of the country has undergone no material change since the commencement of the era of the volcanic eruptions, except such as has resulted from the introduction of new hills of scoriæ, and currents of lava upon the surface. if the lavas could be remelted and poured out again from their respective craters, they would descend the same valleys in which they are now seen, and re-occupy the spaces which they at present fill. the only difference in the external configuration of the fresh lavas would consist in this, that they would nowhere be intersected by ravines, or exhibit marks of erosion by running water. _volcanic cones and lavas._--there are about fourteen distinct cones with craters in this part of spain, besides several points whence lavas may have issued; all of them arranged along a narrow line running north and south, as will be seen in the map. the greatest number of perfect cones are in the immediate neighbourhood of olot, some of which (nos. , . and .) are represented in the annexed woodcut; and the level plain on which that town stands has clearly been produced by the flowing down of many lava-streams from those hills into the bottom of a valley, probably once of considerable depth, like those of the surrounding country. [illustration: fig. . view of the volcanos around olot in catalonia.] in this drawing an attempt is made to represent, by the shading of the landscape, the different geological formations of which the country is composed.[ -a] the white line of mountains (no. .) in the distance is the pyrenees, which are to the north of the spectator, and consist of hypogene and ancient fossiliferous rocks. in front of these are the fossiliferous formations (no. .) which are in shade. the hills , . . are volcanic cones, and the rest of the ground on which the sunshine falls is strewed over with volcanic ashes and lava. the fluvia, which flows near the town of olot, has cut to the depth of only feet through the lavas of the plain before mentioned. the bed of the river is hard basalt; and at the bridge of santa madalena are seen two distinct lava-currents, one above the other, separated by a horizontal bed of scoriæ feet thick. in one place, to the south of olot, the even surface of the plain is broken by a mound of lava, called the "bosque de tosca," the upper part of which is scoriaceous, and covered with enormous heaps of fragments of basalt, more or less porous. between the numerous hummocks thus formed are deep cavities, having the appearance of small craters. the whole precisely resembles some of the modern currents of etna, or that of côme, near clermont; the last of which, like the bosque de tosca, supports only a scanty vegetation. most of the catalonian volcanos are as entire as those in the neighbourhood of naples, or on the flanks of etna. one of these, called montsacopa (no. . fig. .), is of a very regular form, and has a circular depression or crater at the summit. it is chiefly made up of red scoriæ, undistinguishable from that of the minor cones of etna. the neighbouring hills of olivet (no. .) and garrinada (no. .) are of similar composition and shape. the largest crater of the whole district occurs farther to the east of olot, and is called santa margarita. it is feet deep, and about a mile in circumference. like astroni, near naples, it is richly covered with wood, wherein game of various kinds abounds. [illustration: fig. . cross section. _a._ secondary conglomerate. _b._ thin seams of volcanic sand and scoriæ.] although the volcanos of catalonia have broken out through sandstone, shale, and limestone, as have those of the eifel, in germany, to be described in the sequel, there is a remarkable difference in the nature of the ejections composing the cones in these two regions. in the eifel, the quantity of pieces of sandstone and shale thrown out from the vents is often so immense as far to exceed in volume the scoriæ, pumice, and lava; but i sought in vain in the cones near olot for a single fragment of any extraneous rock; and don francisco bolos, an eminent botanist of olot, informed me that he had never been able to detect any. volcanic sand and ashes are not confined to the cones, but have been sometimes scattered by the wind over the country, and drifted into narrow valleys, as is seen between olot and cellent, where the annexed section (fig. .) is exposed. the light cindery volcanic matter rests in thin regular layers, just as it alighted on the slope formed by the solid conglomerate. no flood could have passed through the valley since the scoriæ fell, or these would have been for the most part removed. [illustration: fig. . section above the bridge of cellent. _a._ scoriaceous lava. _b._ schistose basalt. _c._ columnar basalt. _d._ scoria, vegetable soil, and alluvium. _e._ nummulitic limestone. _.f_ micaceous grey sandstone.] the currents of lava in catalonia, like those of auvergne, the vivarais, iceland, and all mountainous countries, are of considerable depth in narrow defiles, but spread out into comparatively thin sheets in places where the valleys widen. if a river has flowed on nearly level ground, as in the great plain near olot, the water has only excavated a channel of slight depth; but where the declivity is great, the stream has cut a deep section, sometimes by penetrating directly through the central part of a lava-current, but more frequently by passing between the lava and the secondary rock which bounds the valley. thus, in the accompanying section, at the bridge of cellent, six miles east of olot, we see the lava on one side of the small stream; while the inclined stratified rocks constitute the channel and opposite bank. the upper part of the lava at that place, as is usual in the currents of etna and vesuvius, is scoriaceous; farther down it becomes less porous, and assumes a spheroidal structure; still lower it divides in horizontal plates, each about inches in thickness, and is more compact. lastly, at the bottom is a mass of prismatic basalt about feet thick. the vertical columns often rest immediately on the subjacent secondary rocks; but there is sometimes an intervention of such sand and scoriæ as cover the country during volcanic eruptions, and which when unprotected, as here, by superincumbent lava, is washed away from the surface of the land. sometimes, the bed _d_ contains a few pebbles and angular fragments of rock; in other places fine earth, which may have constituted an ancient vegetable soil. in several localities, beds of sand and ashes are interposed between the lava and subjacent stratified rock, as may be seen if we follow the course of the lava-current which descends from las planas towards amer, and stops two miles short of that town. the river there has often cut through the lava, and through feet of underlying limestone. occasionally an alluvium, several feet thick, is interspersed between the igneous and marine formation; and it is interesting to remark that in this, as in other beds of pebbles occupying a similar position, there are no rounded fragments of lava; whereas in the most modern gravel-beds of rivers of this country, volcanic pebbles are abundant. the deepest excavation made by a river through lava, which i observed in this part of spain, is that seen in the bottom of a valley near san feliu de palleróls, opposite the castell de stolles. the lava there has filled up the bottom of a valley, and a narrow ravine has been cut through it to the depth of feet. in the lower part the lava has a columnar structure. a great number of ages were probably required for the erosion of so deep a ravine; but we have no reason to infer that this current is of higher antiquity than those of the plain near olot. the fall of the ground, and consequent velocity of the stream, being in this case greater, a more considerable volume of rock may have been removed in the same time. [illustration: fig. . section at castell follit. a. church and town of castell follit, overlooking precipices of basalt. b. small island, on each side of which branches of the river teronel flow to meet the fluvia. _c._ precipice of basaltic lava, chiefly columnar, about feet in height. _d._ ancient alluvium, underlying the lava-current. _e._ inclined strata of secondary sandstone.] i shall describe one more section to elucidate the phenomena of this district. a lava-stream, flowing from a ridge of hills on the east of olot, descends a considerable slope, until it reaches the valley of the river fluvia. here, for the first time, it comes in contact with running water, which has removed a portion, and laid open its internal structure in a precipice about feet in height, at the edge of which stands the town of castell follit. by the junction of the rivers fluvia and teronel, the mass of lava has been cut away on two sides; and the insular rock b (fig. .) has been left, which was probably never so high as the cliff a, as it may have constituted the lower part of the sloping side of the original current. from an examination of the vertical cliffs, it appears that the upper part of the lava on which the town is built is scoriaceous, passing downwards into a spheroidal basalt; some of the huge spheroids being no less than feet in diameter. below this is a more compact basalt, with crystals of olivine. there are in all five distinct ranges of basalt, the uppermost spheroidal, and the rest prismatic, separated by thinner beds not columnar, and some of which are schistose. these were probably formed by successive flows of lava, whether during the same eruption or at different periods. the whole mass rests on alluvium, ten or twelve feet in thickness, composed of pebbles of limestone and quartz, but without any intermixture of igneous rocks; in which circumstance alone it appears to differ from the modern gravel of the fluvia. _bufadors._--the volcanic rocks near olot have often a cavernous structure, like some of the lavas of etna; and in many parts of the hill of batet, in the environs of the town, the sound returned by the earth, when struck, is like that of an archway. at the base of the same hill are the mouths of several subterranean caverns, about twelve in number, which are called in the country "bufadors," from which a current of cold air issues during summer, but which in winter is said to be scarcely perceptible. i visited one of these bufadors in the beginning of august, , when the heat of the season was unusually intense, and found a cold wind blowing from it, which may easily be explained; for as the external air, when rarefied by heat, ascends, the pressure of the colder and heavier air of the caverns in the interior of the mountain causes it to rush out to supply its place. in regard to the age of these spanish volcanos, attempts have been made to prove, that in this country, as well as in auvergne and the eifel, the earliest inhabitants were eye-witnesses to the volcanic action. in the year , it is said, when olot was destroyed by an earthquake, an eruption broke out near amer, and consumed the town. the researches of don francisco bolos have, i think, shown, in the most satisfactory manner, that there is no good historical foundation for the latter part of this story; and any geologist who has visited amer must be convinced that there never was any eruption on that spot. it is true that, in the year above mentioned, the whole of olot, with the exception of a single house, was cast down by an earthquake; one of those shocks which, at distant intervals during the last five centuries, have shaken the pyrenees, and particularly the country between perpignan and olot, where the movements, at the period alluded to, were most violent. the annihilation of the town may, perhaps, have been due to the cavernous nature of the subjacent rocks; for catalonia is beyond the line of those european earthquakes which have, within the period of history, destroyed towns throughout extensive areas. as we have no historical records, then, to guide us in regard to the extinct volcanos, we must appeal to geological monuments. the annexed diagram will present to the reader, in a synoptical form, the results obtained from numerous sections. the more modern alluvium (_d_) is partial, and has been formed by the action of rivers and floods upon the lava; whereas the older gravel (_b_) was strewed over the country before the volcanic eruptions. in neither have any organic remains been discovered; so that we can merely affirm, as yet, that the volcanos broke out after the elevation of some of the newest rocks of the nummulitic (eocene?) series of catalonia, and before the formation of an alluvium (_d_) of unknown date. the integrity of the cones merely shows that the country has not been agitated by violent earthquakes, or subjected to the action of any great transient flood since their origin. [illustration: fig. . superposition of rocks in the volcanic district of catalonia. _a._ sandstone and nummulitic limestone. _b._ older alluvium without volcanic pebbles. _c._ cones of scoriæ and lava. _d._ newer alluvium.] east of olot, on the catalonian coast, marine tertiary strata occur, which, near barcelona, attain the height of about feet. from the shells which i collected, these strata appear to correspond in age with the subapennine beds; and it is not improbable that their upheaval from beneath the sea took place during the period of volcanic eruption round olot. in that case these eruptions may have occurred at the close of the older pliocene era, but perhaps subsequently, for their age is at present quite uncertain. _miocene period--volcanic rocks of the eifel._--the chronological relations of the volcanic rocks of the lower rhine and the eifel are also involved in a considerable degree of ambiguity; but we know that some portion of them were coeval with the deposition of a tertiary formation, called "brown-coal" by the germans, which probably belongs to the miocene, if not referable to the upper eocene, epoch. this brown-coal is seen on both sides of the rhine, in the neighbourhood of bonn, resting unconformably on highly inclined and vertical strata of silurian and devonian rocks. its position, and the space occupied by the volcanic rocks, both of the westerwald and eifel, will be seen by referring to the map in the next page (fig. .), for which i am indebted to mr. horner, whose residence in the country has enabled him to verify the maps of mm. noeggerath and von oeynhausen, from which that now given has been principally compiled. the brown-coal formation consists of beds of loose sand, sandstone, and conglomerate, clay with nodules of clay-ironstone, and occasionally silex. layers of light brown, and sometimes black lignite, are interstratified with the clays and sands, and often irregularly diffused through them. they contain numerous impressions of leaves and stems of trees, and are extensively worked for fuel, whence the name of the formation. [illustration: fig. . map of the volcanic region of the upper and lower eifel. ____ ____ ____ ____ ____ english miles. volcanic district {a. of the upper eifel. {b. of the lower eifel. trachyte. points of eruption, with craters and scoriæ. basalt. brown-coal. _n.b._ the country in that part of the map which is left blank is composed of inclined silurian and devonian rocks.] in several places, layers of trachytic tuff are interstratified, and in these tuffs are leaves of plants identical with those found in the brown-coal, showing that, during the period of the accumulation of the latter, some volcanic products were ejected. the varieties of wood in the lignite are said to belong entirely to dicotyledonous trees; but among the impressions of leaves, collected by mr. horner, some were referred by mr. lindley to a palm, perhaps of the genus _chamærops_, and others resembled the _cinnamomum dulce_, and _podocarpus macrophylla_, which would also indicate a warm climate.[ -a] the other organic remains of the brown-coal are principally fishes; they are found in a bituminous shale, called paper-coal, from being divisible into extremely thin leaves. the individuals are very numerous; but they appear to belong to about five species, which m. agassiz informs me are all extinct, and hitherto peculiar to this brown-coal. they belong to the freshwater genera _leuciscus_, _aspius_, and _perca_. the remains of frogs also, of an extinct species, have been discovered in the paper-coal; and a complete series may be seen in the museum at bonn, from the most imperfect state of the tadpole to that of the full-grown animal. with these a salamander, scarcely distinguishable from the recent species, has been found, and several remains of insects. the brown-coal was evidently a freshwater formation; but fossil shells have been scarcely ever found in it; although near marienforst, in the vicinity of bonn, large blocks have been met with of a white opaque chert, containing numerous casts of freshwater shells, which appear to belong to _planorbis rotundatus_ and _limnea longiscata_, two species common both to the middle and upper eocene periods. it is very probable that the brown-coal may be connected in age with those fluvio-marine formations which are found in higher parts of the valley of the rhine, as at mayence before mentioned (p. .). a vast deposit of gravel, chiefly composed of pebbles of white quartz, but containing also a few fragments of other rocks, lies over the brown-coal formation, forming sometimes only a thin covering, at others attaining a thickness of more than feet. this gravel is very distinct in character from that now forming the bed of the rhine. it is called "kiesel gerolle" by the germans, often reaches great elevations, and is covered in several places with volcanic ejections. it is evident that the country has undergone great changes in its physical geography since this gravel was formed; for its position has scarcely any relation to the existing drainage of the country, and all the more modern volcanic rocks of the same region are posterior to it in date. some of the newest beds of volcanic sand, pumice, and scoriæ are interstratified near andernach and elsewhere with the loam called loess, which was before described as being full of land and freshwater shells of recent species, and referable to the post-pliocene period. i have before hinted (see p. .) that this intercalation of volcanic matter between beds of loess may possibly be explained without supposing the last eruptions of the lower eifel to have taken place so recently as the era of the deposition of the loess; but farther researches should be directed to the investigation of this curious point. the igneous rocks of the westerwald, and of the mountains called the siebengebirge, consist partly of basaltic and partly of trachytic lavas, the latter being in general the more ancient of the two. there are many varieties of trachyte, some of which are highly crystalline, resembling a coarse-grained granite, with large separate crystals of felspar. trachytic tuff is also very abundant. these formations, some of which were certainly contemporaneous with the origin of the brown-coal, were the first of a long series of eruptions, the more recent of which happened when the country had acquired nearly all its present geographical features. _newer volcanos of the eifel.--lake-craters._--as i recognized in the more modern volcanos of the eifel characters distinct from any previously observed by me in those of france, italy, or spain, i shall briefly describe them. the fundamental rocks of the district are grey and red sandstones and shales, with some associated limestones, replete with fossils of the devonian or old red sandstone group. the volcanos broke out in the midst of these inclined strata, and when the present systems of hills and valleys had already been formed. the eruptions occurred sometimes at the bottom of deep valleys, sometimes on the summit of hills, and frequently on intervening platforms. in travelling through this district we often fall upon them most unexpectedly, and may find ourselves on the very edge of a crater before we had been led to suspect that we were approaching the site of any igneous outburst. thus, for example, on arriving at the village of gemund, immediately south of daun, we leave the stream, which flows at the bottom of a deep valley in which strata of sandstone and shale crop out. we then climb a steep hill, on the surface of which we see the edges of the same strata dipping inwards towards the mountain. when we have ascended to a considerable height, we see fragments of scoriæ sparingly scattered over the surface; till, at length, on reaching the summit, we find ourselves suddenly on the edge of a _tarn_, or deep circular lake-basin. [illustration: fig. . the gemunder maar.] [illustration: fig. . cross section. _a._ village of gemund. _b._ gemunder maar. _c._ weinfelder maar. _d._ schalkenmehren maar.] this, which is called the gemunder maar, is the first of three lakes which are in immediate contact, the same ridge forming the barrier of two neighbouring cavities (see fig. .). on viewing the first of these, we recognize the ordinary form of a crater, for which we have been prepared by the occurrence of scoriæ scattered over the surface of the soil. but on examining the walls of the crater we find precipices of sandstone and shale which exhibit no signs of the action of heat; and we look in vain for those beds of lava and scoriæ, dipping in opposite directions on every side, which we have been accustomed to consider as characteristic of volcanic craters. as we proceed, however, to the opposite side of the lake, and afterwards visit the craters _c_ and _d_ (fig. .), we find a considerable quantity of scoriæ and some lava, and see the whole surface of the soil sparkling with volcanic sand, and strewed with ejected fragments of half-fused shale, which preserves its laminated texture in the interior, while it has a vitrified or scoriform coating. a few miles to the south of the lakes above mentioned occurs the pulvermaar of gillenfeld, an oval lake of very regular form, and surrounded by an unbroken ridge of fragmentary materials, consisting of ejected shale and sandstone, and preserving a uniform height of about feet above the water. the side slope in the interior is at an angle of about degrees; on the exterior, of degrees. volcanic substances are intermixed very sparingly with the ejections, which in this place entirely conceal from view the stratified rocks of the country.[ -a] [illustration: fig. . outline of mosenberg, upper eifel.] the meerfelder maar is a cavity of far greater size and depth, hollowed out of similar strata; the sides presenting some abrupt sections of inclined secondary rocks, which in other places are buried under vast heaps of pulverized shale. i could discover no scoriæ amongst the ejected materials, but balls of olivine and other volcanic substances are mentioned as having been found.[ -b] this cavity, which we must suppose to have discharged an immense volume of gas, is nearly a mile in diameter, and is said to be more than one hundred fathoms deep. in the neighbourhood is a mountain called the mosenberg, which consists of red sandstone and shale in its lower parts, but supports on its summit a triple volcanic cone, while a distinct current of lava is seen descending the flanks of the mountain. the edge of the crater of the largest cone reminded me much of the form and characters of that of vesuvius; but i was much struck with the precipitous and almost overhanging wall or parapet which the scoriæ presented towards the exterior, as at _a b_ (fig. .); which i can only explain by supposing that fragments of red-hot lava, as they fell round the vent, were cemented together into one compact mass, in consequence of continuing to be in a half-melted state. if we pass from the upper to the lower eifel, from a to b (see map, p. .), we find the celebrated lake-crater of laach, which has a greater resemblance than any of those before mentioned to the lago di bolsena, and others in italy--being surrounded by a ridge of gently sloping hills, composed of loose tuffs, scoriæ, and blocks of a variety of lavas. one of the most interesting volcanos on the left bank of the rhine is called the roderberg. it forms a circular crater nearly a quarter of a mile in diameter, and feet deep, now covered with fields of corn. the highly inclined strata of ancient sandstone and shale rise even to the rim of one side of the crater; but they are overspread by quartzose gravel, and this again is covered by volcanic scoriæ and tufaceous sand. the opposite wall of the crater is composed of cinders and scorified rock, like that at the summit of vesuvius. it is quite evident that the eruption in this case burst through the sandstone and alluvium which immediately overlies it; and i observed some of the quartz pebbles mixed with scoriæ on the flanks of the mountain, as if they had been cast up into the air, and had fallen again with the volcanic ashes. i have already observed, that a large part of this crater has been filled up with loess (p. .). the most striking peculiarity of a great many of the craters above described, is the absence of any signs of alteration or torrefaction in their walls, when these are composed of regular strata of ancient sandstone and shale. it is evident that the summits of hills formed of the above-mentioned stratified rocks have, in some cases, been carried away by gaseous explosions, while at the same time no lava, and often a very small quantity only of scoriæ, has escaped from the newly formed cavity. there is, indeed, no feature in the eifel volcanos more worthy of note, than the proofs they afford of very copious aëriform discharges, unaccompanied by the pouring out of melted matter, except, here and there, in very insignificant volume. i know of no other extinct volcanos where gaseous explosions of such magnitude have been attended by the emission of so small a quantity of lava. yet i looked in vain in the eifel for any appearances which could lend support to the hypothesis, that the sudden rushing out of such enormous volumes of gas had ever lifted up the stratified rocks immediately around the vent, so as to form conical masses, having their strata dipping outwards on all sides from a central axis, as is assumed in the theory of elevation craters, alluded to at the end of chap. xxix. _trass._--in the lower eifel, eruptions of trachytic lava preceded the emission of currents of basalt, and immense quantities of pumice were thrown out wherever trachyte issued. the tufaceous alluvium called _trass_, which has covered large areas in this region and choked up some valleys now partially re-excavated, is unstratified. its base consists almost entirely of pumice, in which are included fragments of basalt and other lavas, pieces of burnt shale, slate, and sandstone, and numerous trunks and branches of trees. if this trass was formed during the period of volcanic eruptions it may perhaps have originated in the manner of the moya of the andes. we may easily conceive that a similar mass might now be produced, if a copious evolution of gases should occur in one of the lake basins. the water might remain for weeks in a state of violent ebullition, until it became of the consistency of mud, just as the sea continued to be charged with red mud round graham's island, in the mediterranean, in the year . if a breach should then be made in the side of the cone, the flood would sweep away great heaps of ejected fragments of shale and sandstone, which would be borne down into the adjoining valleys. forests might be torn up by such a flood, and thus the occurrence of the numerous trunks of trees dispersed irregularly through the trass, can be explained. _hungary._--m. beudant, in his elaborate work on hungary, describes five distinct groups of volcanic rocks, which although nowhere of great extent, form striking features in the physical geography of that country, rising as they do abruptly from extensive plains composed of tertiary strata. they may have constituted islands in the ancient sea, as santorin and milo now do in the grecian archipelago; and m. beudant has remarked that the mineral products of the last-mentioned islands resemble remarkably those of the hungarian extinct volcanos, where many of the same minerals as opal, calcedony, resinous silex (_silex resinite_), pearlite, obsidian, and pitchstone abound. the hungarian lavas are chiefly felspathic, consisting of different varieties of trachyte; many are cellular, and used as millstones; some so porous and even scoriform as to resemble those which have issued in the open air. pumice occurs in great quantity; and there are conglomerates, or rather breccias, wherein fragments of trachyte are bound together by pumiceous tuff, or sometimes by silex. it is probable that these rocks were permeated by the waters of hot springs, impregnated, like the geysers, with silica; or in some instances, perhaps, by aqueous vapours, which, like those of lancerote, may have precipitated hydrate of silica. by the influence of such springs or vapours the trunks and branches of trees washed down during floods, and buried in tuffs on the flanks of the mountains, are supposed to have become silicified. it is scarcely possible, says m. beudant, to dig into any of the pumiceous deposits of these mountains without meeting with opalized wood, and sometimes entire silicified trunks of trees of great size and weight. it appears from the species of shells collected principally by m. boué, and examined by m. deshayes, that the fossil remains imbedded in the volcanic tuffs, and in strata alternating with them in hungary, are of the miocene type, and not identical, as was formerly supposed, with the fossils of the paris basin. footnotes: [ -a] maclure, journ. de phys., vol. lxvi. p. ., ; cited by daubeny, description of volcanos, p. . [ -a] this view is taken from a sketch which i made on the spot in . [ -a] trans. of geol. soc., d series, vol. v. [ -a] scrope, edin. journ. of sci., june, , p. . [ -b] hibbert, extinct volcanos of the rhine, p. . chapter xxxii. on the different ages of the volcanic rocks--_continued_. volcanic rocks of the pliocene and miocene periods continued--auvergne--mont dor--breccias and alluviums of mont perrier, with bones of quadrupeds--river dammed up by lava-current--range of minor cones from auvergne to the vivarais--monts dome--puy de côme--puy de pariou--cones not denuded by general flood--velay--bones of quadrupeds buried in scoriæ--cantal--eocene volcanic rocks--tuffs near clermont--hill of gergovia--trap of cretaceous period--oolitic period--new red sandstone period--carboniferous period--old red sandstone period--"rock and spindle" near st. andrews--silurian period--cambrian volcanic rocks. _tertiary volcanic rocks.--auvergne._--the extinct volcanos of auvergne and cantal in central france seem to have commenced their eruptions in the upper eocene period, but to have been most active during the miocene and pliocene eras. i have already alluded to the grand succession of events, of which there is evidence in auvergne since the last retreat of the sea (see p. .). the earliest monuments of the tertiary period in that region are lacustrine deposits of great thickness ( . fig. . p. .), in the lowest conglomerates of which are rounded pebbles of quartz, mica-schist, granite, and other non-volcanic rocks, without the slightest intermixture of igneous products. to these conglomerates succeed argillaceous and calcareous marls and limestones ( . fig. .) containing upper eocene shells and bones of mammalia, the higher beds of which sometimes alternate with volcanic tuff of contemporaneous origin. after the filling up or drainage of the ancient lakes, huge piles of trachytic and basaltic rocks, with volcanic breccias, accumulated to a thickness of several thousand feet, and were superimposed upon granite, or the contiguous lacustrine strata. the greater portion of these igneous rocks appear to have originated during the miocene and pliocene periods; and extinct quadrupeds of those eras, belonging to the genera mastodon, rhinoceros, and others, were buried in ashes and beds of alluvial sand and gravel, which owe their preservation to overspreading sheets of lava. in auvergne the most ancient and conspicuous of the volcanic masses is mont dor, which rests immediately on the granitic rocks standing apart from the freshwater strata.[ -a] this great mountain rises suddenly to the height of several thousand feet above the surrounding platform, and retains the shape of a flattened and somewhat irregular cone, all the sides sloping more or less rapidly, until their inclination is gradually lost in the high plain around. this cone is composed of layers of scoriæ, pumice-stones, and their fine detritus, with interposed beds of trachyte and basalt, which descend often in uninterrupted sheets, till they reach and spread themselves round the base of the mountain.[ -a] conglomerates, also, composed of angular and rounded fragments of igneous rocks, are observed to alternate with the above; and the various masses are seen to dip off from the central axis, and to lie parallel to the sloping flanks of the mountain. the summit of mont dor terminates in seven or eight rocky peaks, where no regular crater can now be traced, but where we may easily imagine one to have existed, which may have been shattered by earthquakes, and have suffered degradation by aqueous agents. originally, perhaps, like the highest crater of etna, it may have formed an insignificant feature in the great pile, and may frequently have been destroyed and renovated. according to some geologists, this mountain, as well as vesuvius, etna, and all large volcanos, has derived its dome-like form not from the preponderance of eruptions from one or more central points, but from the upheaval of horizontal beds of lava and scoriæ. i have explained my reasons for objecting to this view at the close of chap. xxix., when speaking of palma, and in the principles of geology.[ -b] the average inclination of the dome-shaped mass of mont dor is ° ', whereas in mounts loa and kea, before mentioned, in the sandwich islands (see fig. . p. .), the flanks of which have been raised by recent lavas, we find from mr. dana's description that the one has a slope of ° ', the other of ° '. we may, therefore, reasonably question whether there is any absolute necessity for supposing that the basaltic currents of the ancient french volcano were at first more horizontal than they are now. nevertheless it is highly probable that during the long series of eruptions required to give rise to so vast a pile of volcanic matter, which is thickest at the summit or centre of the dome, some dislocation and upheaval took place; and during the distension of the mass, beds of lava and scoriæ may, in some places, have acquired a greater, in others a less inclination, than that which at first belonged to them. respecting the age of the great mass of mont dor, we cannot come at present to any positive decision, because no organic remains have yet been found in the tuffs, except impressions of the leaves of trees of species not yet determined. we may certainly conclude, that the earliest eruptions were posterior in origin to those grits, and conglomerates of the freshwater formation of the limagne, which contain no pebbles of volcanic rocks; while, on the other hand, some eruptions took place before the great lakes were drained; and others occurred after the desiccation of those lakes, and when deep valleys had already been excavated through freshwater strata. in the annexed section, i have endeavoured to explain the geological structure of a portion of auvergne, which i re-examined in .[ -c] it may convey some idea to the reader of the long and complicated series of events, which have occurred in that country, since the first lacustrine strata (no. .) were deposited on the granite (no. .). the changes of which we have evidence are the more striking, because they imply great denudation, without there being any proofs of the intervention of the sea during the whole period. it will be seen that the upper freshwater beds (no. .), once formed in a lake, must have suffered great destruction before the excavation of the valleys of the couze and allier had begun. in these freshwater beds, upper eocene fossils, as described in chap. xv., have been found. the basaltic dike ' is one of many examples of the intrusion of volcanic matter through the eocene freshwater beds, and may have been of upper eocene or miocene date, giving rise, when it reached the surface and overflowed, to such platforms of basalt, as often cap the tertiary hills in auvergne, and one of which ( ) is seen on mont perrier. [illustration: fig. . section from the valley of the couze at nechers, through mont perrier and issoire to the valley of the allier, and the tour de boulade, auvergne. . lava-current of tartaret near its termination at nechers. . bone-bed, red sandy clay under the lava of tartaret. . bone-bed of the tour de boulade. . alluvium newer than no. . . alluvium with bones of hippopotamus. _c._ trachytic breccia resembling _a._ _b._ upper bone-bed of perrier, gravel, &c. _a._ pumiceous breccia and conglomerate, angular masses of trachyte, quartz, pebbles, &c. . lower bone-bed of perrier, ochreous sand and gravel. _a._ basaltic dyke. . basaltic platform. . upper freshwater beds, limestone, marl, gypsum, &c. . lower freshwater formation, red clay, green sand, &c. . granite.] it not unfrequently happens that beds of gravel containing bones of extinct mammalia are detected under these very ancient sheets of basalt, as between no. . and the freshwater strata, no. ., at a, from which it is clear that the surface of formed at that period the lowest level at which the waters then draining the country flowed. next in age to this basaltic platform comes a patch of ochreous sand and gravel (no. .), containing many bones of quadrupeds. upon this rests a pumiceous breccia and conglomerate, with angular masses of trachyte, and some quartz pebbles. this deposit is followed by _b_, which is similar to , and _c_ similar to the trachytic breccia _a_. these two breccias are supposed, from their similarity to others found on mount dor, to have descended from the flanks of that mountain during eruptions; and the interstratified alluvial deposits contain the remains of mastodon, rhinoceros, tapir, deer, beaver, and quadrupeds of other genera referable to about forty species, all of which are extinct. i formerly supposed them to belong to the same era as the miocene faluns of touraine; but, whether they may not rather be ascribed to the older pliocene epoch is a question which farther inquiries and comparisons must determine. whatever be their date in the tertiary series, they are quadrupeds which inhabited the country when the formations and _c_ originated. probably they were drowned during floods, such as rush down the flanks of volcanos during eruptions, when great bodies of steam are emitted from the crater, or when, as we have seen, both on etna and in iceland in modern times, large masses of snow are suddenly melted by lava, causing a deluge of water to bear down fragments of igneous rocks mixed with mud, to the valleys and plains below. it will be seen that the valley of the issoire, down which these ancient inundations swept, was first excavated at the expense of the formations , , and , and then filled up by the masses and _c_, after which it was re-excavated before the more modern alluviums (nos. . and .) were formed. in these again other fossil mammalia of distinct species have been detected by m. bravard, the bones of an hippopotamus having been found among the rest. at length, when the valley of the allier was eroded at issoire down to its lowest level, a talus of angular fragments of basalt and freshwater limestone (no. .) was formed, called the bone-bed of the tour de boulade, from which a great many other mammalia have been collected by mm. bravard and pomel. in this assemblage the _elephas primigenius_, _rhinoceros tichorinus_, _deer_ (including rein-deer), _equus_, _bos_, _antelope_, _felis_, and _canis_, were included. even this deposit seems hardly to be the newest in the neighbourhood, for if we cross from the town of issoire (see fig. .) over mont perrier to the adjoining valley of the couze, we find another bone-bed (no. .), overlaid by a current of lava (no. .). the history of this lava-current, which terminates a few hundred yards below the point no. ., in the suburbs of the village of nechers, is interesting. it forms a long narrow stripe more than miles in length, at the bottom of the valley of the couze, which flows out of a lake at the foot of mont dor. this lake is caused by a barrier thrown across the ancient channel of the couze, consisting partly of the volcanic cone called the puy de tartaret, formed of loose scoriæ, from the base of which has issued the lava-current before mentioned. the materials of the dam which blocked up the river, and caused the lac de chambon, are also, in part, derived from a land-slip which may have happened at the time of the great eruption which formed the cone. this cone of tartaret affords an impressive monument of the very different dates at which the igneous eruptions of auvergne have happened; for it was evidently thrown up at the bottom of the existing valley, which is bounded by lofty precipices composed of sheets of ancient columnar trachyte and basalt, which once flowed at very high levels from mont dor.[ -a] when we follow the course of the river couze, from its source in the lake of chambon, to the termination of the lava-current at nechers, a distance of thirteen miles, we find that the torrent has in most places cut a deep channel through the lava, the lower portion of which is columnar. in some narrow gorges it has even had power to remove the entire mass of basaltic rock, though the work of erosion must have been very slow, as the basalt is tough and hard, and one column after another must have been undermined and reduced to pebbles, and then to sand. during the time required for this operation, the perishable cone of tartaret, composed of sand and ashes, has stood uninjured, proving that no great flood or deluge can have passed over this region in the interval between the eruption of tartaret and our own times. if we now return to the section (fig. .), i may observe that the lava-current of tartaret, which has diminished greatly in height and volume near its termination, presents here a steep and perpendicular face feet in height towards the river. beneath it is the alluvium no. ., consisting of a red sandy clay, which must have covered the bottom of the valley when the current of melted rock flowed down. the bones found in this alluvium, which i obtained myself, consisted of a species of field-mouse, _arvicola_, and the molar tooth of an extinct horse, _equus fossilis_. the other species, obtained from the same bed, are referable to the genera _sus_, _bos_, _cervus_, _felis_, _canis_, _martes_, _talpa_, _sorex_, _lepus_, _sciurus_, _mus_, and _lagomys_, in all no less than forty-three species, all closely allied to recent animals, yet nearly all of them, according to m. bravard, showing some points of difference, like those which mr. owen discovered in the case of the horse above alluded to. the bones, also, of a frog, snake, and lizard, and of several birds, were associated with the fossils before enumerated, and several recent land shells, such as _cyclostoma elegans_, _helix hortensis_, _h. nemoralis_, _h. lapicida_, and _clausilia rugosa_. if the animals were drowned by floods, which accompanied the eruptions of the puy de tartaret, they would give an exceedingly modern geological date to that event, which must, in that case, have belonged to the newer-pliocene, or, perhaps, the post-pliocene period. that the current, which has issued from the puy de tartaret, may nevertheless be very ancient in reference to the events of human history, we may conclude, not only from the divergence of the mammiferous fauna from that of our day, but from the fact that a roman bridge of such form and construction as continued in use down to the fifth century, but which may be older, is now seen at a place about a mile and a half from st. nectaire. this ancient bridge spans the river couze with two arches, each about feet wide. these arches spring from the lava of tartaret, on both banks, showing that a ravine precisely like that now existing, had already been excavated by the river through that lava thirteen or fourteen centuries ago. in central france there are several hundred minor cones, like that of tartaret, a great number of which, like monte nuovo, near naples, may have been principally due to a single eruption. most of these cones range in a linear direction from auvergne to the vivarais, and they were faithfully described so early as the year , by m. de montlosier. they have given rise chiefly to currents of basaltic lava. those of auvergne called the monts dome, placed on a granitic platform, form an irregular ridge (see fig. .), about miles in length, and in breadth. they are usually truncated at the summit, where the crater is often preserved entire, the lava having issued from the base of the hill. but frequently the crater is broken down on one side, where the lava has flowed out. the hills are composed of loose scoriæ, blocks of lava, lapilli, and pozzuolana, with fragments of trachyte and granite. _puy de côme._--the puy de côme and its lava-current, near clermont, may be mentioned as one of these minor volcanos. this conical hill rises from the granitic platform, at an angle of about °, to the height of more than feet. its summit presents two distinct craters, one of them with a vertical depth of feet. a stream of lava takes its rise at the western base of the hill, instead of issuing from either crater, and descends the granitic slope towards the present site of the town of pont gibaud. thence it pours in a broad sheet down a steep declivity into the valley of the sioule, filling the ancient river-channel for the distance of more than a mile. the sioule, thus dispossessed of its bed, has worked out a fresh one between the lava and the granite of its western bank; and the excavation has disclosed, in one spot, a wall of columnar basalt about feet high.[ -a] the excavation of the ravine is still in progress, every winter some columns of basalt being undermined and carried down the channel of the river, and in the course of a few miles rolled to sand and pebbles. meanwhile the cone of côme remains stationary, its loose materials being protected by a dense vegetation, and the hill standing on a ridge not commanded by any higher ground whence floods of rain-water may descend. _puy rouge._--at another point, farther down the course of the sioule, we find a second illustration of the same phenomenon in the puy rouge, a conical hill to the north of the village of pranal. the cone is composed entirely of red and black scoriæ, tuff, and volcanic bombs. on its western side there is a worn-down crater, whence a powerful stream of lava has issued, and flowed into the valley of the sioule. the river has since excavated a ravine through the lava and subjacent gneiss, to the depth of feet. on the upper part of the precipice forming the left side of this ravine, we see a great mass of black and red scoriaceous lava; below this a thin bed of gravel, evidently an ancient river-bed, now at an elevation of feet above the channel of the sioule. the gravel again rests upon gneiss, which has been eroded to the depth of feet. it is quite evident in this case, that, while the basalt was gradually undermined and carried away by the force of running water, the cone whence the lava issued escaped destruction, because it stood upon a platform of gneiss several hundred feet above the level of the valley in which the force of running water was exerted. _puy de pariou._--the brim of the crater of the puy de pariou, near clermont, is so sharp, and has been so little blunted by time, that it scarcely affords room to stand upon. this and other cones in an equally remarkable state of integrity have stood, i conceive uninjured, not _in spite_ of their loose porous nature, as might at first be naturally supposed, but in consequence of it. no rills can collect where all the rain is instantly absorbed by the sand and scoriæ, as is remarkably the case on etna; and nothing but a waterspout breaking directly upon the puy de pariou could carry away a portion of the hill, so long as it is not rent or engulphed by earthquakes. hence it is conceivable that even those cones which have the freshest aspect, and most perfect shape, may lay claim to very high antiquity. dr. daubeny has justly observed, that had any of these volcanos been in a state of activity in the age of julius cæsar, that general, who encamped upon the plains of auvergne, and laid siege to its principal city (gergovia, near clermont), could hardly have failed to notice them. had there been any record of their eruptions in the time of pliny or sidonius apollinaris, the one would scarcely have omitted to make mention of it in his natural history, nor the other to introduce some allusion to it among the descriptions of this his native province. this poet's residence was on the borders of the lake aidat, which owed its very existence to the damming up of a river by one of the most modern lava-currents.[ -a] _velay._--the observations of m. bertrand de doue have not yet established that any of the most ancient volcanos of velay were in action during the eocene period. there are beds of gravel in velay, as in auvergne, covered by lava at different heights above the channels of the existing rivers. in the highest and most ancient of these alluviums the pebbles are exclusively of granitic rocks; but in the newer, which are found at lower levels, and which originated when the valleys had been cut to a greater depth, an intermixture of volcanic rocks has been observed. at st. privat d'allier a bed of volcanic scoriæ and tuff was discovered by dr. hibbert, inclosed between two sheets of basaltic lava; and in this tuff were found the bones of several quadrupeds, some of them adhering to masses of slaggy lava. among other animals were _rhinoceros leptorhinus_, _hyæna spelæa_, and a species allied to the spotted hyæna of the cape, together with four undetermined species of deer.[ -b] the manner of the occurrence of these bones reminds us of the published accounts of an eruption of coseguina, , in central america (see p. .), during which hot cinders and scoriæ fell and scorched to death great numbers of wild and domestic animals and birds. _plomb du cantal._--in regard to the age of the igneous rocks of the cantal, we can at present merely affirm, that they overlie the eocene lacustrine strata of that country (see map, p. .). they form a great dome-shaped mass, having an average slope of only °, which has evidently been accumulated, like the cone of etna, during a long series of eruptions. it is composed of trachytic, phonolitic, and basaltic lavas, tuffs, and conglomerates, or breccias, forming a mountain several thousand feet in height. dikes also of phonolite, trachyte, and basalt are numerous, especially in the neighbourhood of the large cavity, probably once a crater, around which the loftiest summits of the cantal are ranged circularly, few of them, except the plomb du cantal, rising far above the border or ridge of this supposed crater. a pyramidal hill, called the puy griou, occupies the middle of the cavity.[ -a] it is clear that the volcano of the cantal broke out precisely on the site of the lacustrine deposit before described (p. .), which had accumulated in a depression of a tract composed of micaceous schist. in the breccias, even to the very summit of the mountain, we find ejected masses of the freshwater beds, and sometimes fragments of flint, containing eocene shells. valleys radiate in all directions from the central heights of the mountain, increasing in size as they recede from those heights. those of the cer and jourdanne, which are more than miles in length, are of great depth, and lay open the geological structure of the mountain. no alternation of lavas with undisturbed eocene strata has been observed, nor any tuffs containing freshwater shells, although some of these tuffs include fossil remains of terrestrial plants, said to imply several distinct restorations of the vegetation of the mountain in the intervals between great eruptions. on the northern side of the plomb du cantal, at la vissiere, near murat, is a spot, pointed out on the map (p. .), where freshwater limestone and marl are seen covered by a thickness of about feet of volcanic rock. shifts are here seen in the strata of limestone and marl.[ -b] _eocene period._--in treating of the lacustrine deposits of central france, in the fifteenth chapter, it was stated that, in the arenaceous and pebbly group of the lacustrine basins of auvergne, cantal, and velay, no volcanic pebbles had ever been detected, although massive piles of igneous rocks are now found in the immediate vicinity. as this observation has been confirmed by minute research, we are warranted in inferring that the volcanic eruptions had not commenced when the older subdivisions of the freshwater groups originated. in cantal and velay no decisive proofs have yet been brought to light that any of the igneous outbursts happened during the deposition of the freshwater strata; but there can be no doubt that in auvergne some volcanic explosions took place before the drainage of the lakes, and at a time when the upper eocene species of animals and plants still flourished. thus, for example, at pont du chateau, near clermont, a section is seen in a precipice on the right bank of the river allier, in which beds of volcanic tuff alternate with a freshwater limestone, which is in some places pure, but in others spotted with fragments of volcanic matter, as if it were deposited while showers of sand and scoriæ were projected from a neighbouring vent.[ -a] another example occurs in the puy de marmont, near veyres, where a freshwater marl alternates with volcanic tuff containing eocene shells. the tuff or breccia in this locality is precisely such as is known to result from volcanic ashes falling into water, and subsiding together with ejected fragments of marl and other stratified rocks. these tuffs and marls are highly inclined, and traversed by a thick vein of basalt, which, as it rises in the hill, divides into two branches. _gergovia._--the hill of gergovia, near clermont, affords a third example. i agree with mm. dufrénoy and jobert that there is no alternation here of a contemporaneous sheet of lava with freshwater strata, in the manner supposed by some other observers[ -b]; but the position and contents of some of the associated tuffs, prove them to have been derived from volcanic eruptions which occurred during the deposition of the lacustrine strata. [illustration: fig. . hill of gergovia.] the bottom of the hill consists of slightly inclined beds of white and greenish marls, more than feet in thickness, intersected by a dike of basalt, which may be studied in the ravine above the village of merdogne. the dike here cuts through the marly strata at a considerable angle, producing, in general, great alteration and confusion in them for some distance from the point of contact. above the white and green marls, a series of beds of limestone and marl, containing freshwater shells, are seen to alternate with volcanic tuff. in the lowest part of this division, beds of pure marl alternate with compact fissile tuff, resembling some of the subaqueous tuffs of italy and sicily called _peperinos_. occasionally fragments of scoriæ are visible in this rock. still higher is seen another group of some thickness, consisting exclusively of tuff, upon which lie other marly strata intermixed with volcanic matter. among the species of fossil shells which i found in these strata were _melania inquinata_, a _unio_, and a _melanopsis_, but they were not sufficient to enable me to determine with precision the age of the formation. there are many points in auvergne where igneous rocks have been forced by subsequent injection through clays and marly limestones, in such a manner that the whole has become blended in one confused and brecciated mass, between which and the basalt there is sometimes no very distinct line of demarcation. in the cavities of such mixed rocks we often find calcedony, and crystals of mesotype, stilbite, and arragonite. to formations of this class may belong some of the breccias immediately adjoining the dike in the hill of gergovia; but it cannot be contended that the volcanic sand and scoriæ interstratified with the marls and limestones in the upper part of that hill were introduced, like the dike, subsequently, by intrusion from below. they must have been thrown down like sediment from water, and can only have resulted from igneous action, which was going on contemporaneously with the deposition of the lacustrine strata. the reader will bear in mind that this conclusion agrees well with the proofs, adverted to in the fifteenth chapter, of the abundance of silex, travertin, and gypsum precipitated when the upper lacustrine strata were formed; for these rocks are such as the waters of mineral and thermal springs might generate. _cretaceous period._--although we have no proof of volcanic rocks erupted in england during the deposition of the chalk and greensand, it would be an error to suppose that no theatres of igneous action existed in the cretaceous period. m. virlet, in his account of the geology of the morea, p. ., has clearly shown that certain traps in greece, called by him ophiolites, are of this date; as those, for example, which alternate conformably with cretaceous limestone and greensand between kastri and damala in the morea. they consist in great part of diallage rocks and serpentine, and of an amygdaloid with calcareous kernels, and a base of serpentine. in certain parts of the morea, the age of these volcanic rocks is established by the following proofs: first, the lithographic limestones of the cretaceous era are cut through by trap, and then a conglomerate occurs, at nauplia and other places, containing in its calcareous cement many well-known fossils of the chalk and greensand, together with pebbles formed of rolled pieces of the same ophiolite, which appear in the dikes above alluded to. _period of oolite and lias._--although the green and serpentinous trap rocks of the morea belong chiefly to the cretaceous era, as before mentioned, yet it seems that some eruptions of similar rocks began during the oolitic period[ -a]; and it is probable, that a large part of the trappean masses, called ophiolites in the apennines, and associated with the limestone of that chain, are of corresponding age. that part of the volcanic rocks of the hebrides, in our own country, originated contemporaneously with the oolite which they traverse and overlie, has been ascertained by prof. e. forbes, in . _trap of the new red sandstone period._--in the southern part of devonshire, trappean rocks are associated with new red sandstone, and, according to sir h. de la beche, have not been intruded subsequently into the sandstone, but were produced by contemporaneous volcanic action. some beds of grit, mingled with ordinary red marl, resemble sands ejected from a crater; and in the stratified conglomerates occurring near tiverton are many angular fragments of trap porphyry, some of them one or two tons in weight, intermingled with pebbles of other rocks. these angular fragments were probably thrown out from volcanic vents, and fell upon sedimentary matter then in the course of deposition.[ -a] _carboniferous period._--two classes of contemporaneous trap rocks have been ascertained by dr. fleming to occur in the coal-field of the forth in scotland. the newest of these, connected with the higher series of coal-measures, is well exhibited along the shores of the forth, in fifeshire, where they consist of basalt with olivine, amygdaloid, greenstone, wacké, and tuff. they appear to have been erupted while the sedimentary strata were in a horizontal position, and to have suffered the same dislocations which those strata have subsequently undergone. in the volcanic tuffs of this age are found not only fragments of limestone, shale, flinty slate, and sandstone, but also pieces of coal. the other or older class of carboniferous traps are traced along the south margin of stratheden, and constitute a ridge parallel with the ochils, and extending from stirling to near st. andrews. they consist almost exclusively of greenstone, becoming, in a few instances, earthy and amygdaloidal. they are regularly interstratified with the sandstone, shale, and ironstone of the lower coal-measures, and, on the east lomond, with mountain limestone. i examined these trap rocks in , in the cliffs south of st. andrews, where they consist in great part of stratified tuffs, which are curved, vertical, and contorted, like the associated coal-measures. in the tuff i found fragments of carboniferous shale and limestone, and intersecting veins of greenstone. at one spot, about two miles from st. andrews, the encroachment of the sea on the cliffs has isolated several masses of trap, one of which (fig. .) is aptly called the "rock and spindle,"[ -b] for it consists of a pinnacle of tuff, which may be compared to a distaff, and near the base is a mass of columnar greenstone, in which the pillars radiate from a centre, and appear at a distance like the spokes of a wheel. the largest diameter of this wheel is about twelve feet, and the polygonal terminations of the columns are seen round the circumference (or tire, as it were, of the wheel), as in the accompanying figure. i conceive this mass to be the extremity of a string or vein of greenstone, which penetrated the tuff. the prisms point in every direction, because they were surrounded on all sides by cooling surfaces, to which they always, arrange themselves at right angles, as before explained (p. .). [illustration: fig. . rock and spindle, st. andrews. _a._ unstratified tuff. _b._ columnar greenstone. _c._ stratified tuff.] [illustration: fig. . columns of greenstone, seen endwise.] a trap dike was pointed out to me by dr. fleming, in the parish of flisk, in the northern part of fifeshire, which cuts through the grey sandstone and shale, forming the lowest part of the old red sandstone. it may be traced for many miles, passing through the amygdaloidal and other traps of the hill called normans law. in its course it affords a good exemplification of the passage from the trappean into the plutonic, or highly crystalline texture. professor gustavus rose, to whom i submitted specimens of this dike, finds the rock, which he calls dolerite, to consist of greenish black augite and labrador felspar, the latter being the most abundant ingredient. a small quantity of magnetic iron, perhaps titaniferous, is also present. the result of this analysis is interesting, because both the ancient and modern lavas of etna consist in like manner of augite, labradorite, and titaniferous iron. _trap of the old red sandstone period._--by referring to the section explanatory of the structure of forfarshire, already given (p. .), the reader will perceive that beds of conglomerate, no. ., occur in the middle of the old red sandstone system, , , , . the pebbles in these conglomerates are sometimes composed of granitic and quartz rocks, sometimes exclusively of different varieties of trap, which, although purposely omitted in the above section, are often found either intruding themselves in amorphous masses and dikes into the old fossiliferous tilestones, no. ., or alternating with them in conformable beds. all the different divisions of the red sandstone, , , , , are occasionally intersected by dikes, but they are very rare in nos. . and ., the upper members of the group consisting of red shale and red sandstone. these phenomena, which occur at the foot of the grampians, are repeated in the sidlaw hills; and it appears that in this part of scotland, volcanic eruptions were most frequent in the earlier part of the old red sandstone period. the trap rocks alluded to consist chiefly of felspathic porphyry and amygdaloid, the kernels of the latter being sometimes calcareous, often calcedonic, and forming beautiful agates. we meet also with claystone, clinkstone, greenstone, compact felspar, and tuff. some of these rocks flowed as lavas over the bottom of the sea, and enveloped quartz pebbles which were lying there, so as to form conglomerates with a base of greenstone, as is seen in lumley den, in the sidlaw hills. on either side of the axis of this chain of hills (see section, p. .), the beds of massive trap, and the tuffs composed of volcanic sand and ashes, dip regularly to the south-east or north-west, conformably with the shales and sandstones. _silurian period._--it appears from the investigations of sir r. murchison in shropshire, that when the lower silurian strata of that county were accumulating, there were frequent volcanic eruptions beneath the sea; and the ashes and scoriæ then ejected gave rise to a peculiar kind of tufaceous sandstone or grit, dissimilar to the other rocks of the silurian series, and only observable in places where syenitic and other trap rocks protrude. these tuffs occur on the flanks of the wrekin and caer caradoc, and contain silurian fossils, such as casts of encrinites, trilobites, and mollusca. although fossiliferous, the stone resembles a sandy claystone of the trap family.[ -a] thin layers of trap, only a few inches thick, alternate, in some parts of shropshire and montgomeryshire, with sedimentary strata of the lower silurian system. this trap consists of slaty porphyry and granular felspar rock, the beds being traversed by joints like those in the associated sandstone, limestone, and shale, and having the same strike and dip.[ -b] in radnorshire there is an example of twelve bands of stratified trap, alternating with silurian schists and flagstones, in a thickness of feet. the bedded traps consist of felspar-porphyry, clinkstone, and other varieties; and the interposed llandeilo flags are of sandstone and shale, with trilobites and graptolites.[ -c] the vast thickness of contemporaneous trappean rocks of lower silurian date in north wales, explored by our government surveyors, has been already alluded to.[ -d] _cambrian volcanic rocks._--professor sedgwick, in his account of the geology of cumberland, has described various trap rocks which accompany the green slates of the cambrian system, beneath all the rocks containing organic remains. different felspathic and porphyritic rocks and greenstones occur, not only in dikes, but in conformable beds; and there is occasionally a passage from these igneous rocks to some of the green quartzose slates. professor sedgwick supposes these porphyries to have originated contemporaneously with the stratified chloritic slates, the materials of the slates having been supplied, in part at least, by submarine eruptions oftentimes repeated.[ -e] footnotes: [ -a] see the map, p. . [ -a] scrope's central france, p. . [ -b] see chaps. xxiv., xxv., and xxvi., th and th editions. [ -c] see quarterly geol. journ., vol. ii. p. . [ -a] for a view of puy de tartaret and mont dor, see scrope's volcanos of central france. [ -a] scrope's central france, p. ., and plate. [ -a] daubeny on volcanos, p. . [ -b] edin. journ. of sci., no. iv. n. s. p. . figures of some of these remains are given by m. bertrand de doue, ann. de la soc. d'agricult. de puy, . [ -a] mém. de la soc. géol. de france, tom. i. p. . [ -b] see lyell and murchison, ann. de sci. nat., oct. . [ -a] see scrope's central france, p. . [ -b] ibid, p. . [ -a] boblaye and virlet, morea, p. . [ -a] de la beche, geol. proceedings, no. . p. . [ -b] "the rock," as english readers of burn's poems may remember, is a scotch term for distaff. [ -a] murchison, silurian system, &c. p. . [ -b] ibid., p. . [ -c] ibid., p. . [ -d] chap. xxvii. p. . [ -e] geol. trans., d series, vol. iv. p. . chapter xxxiii. plutonic rocks--granite. general aspect of granite--decomposing into spherical masses--rude columnar structure--analogy and difference of volcanic and plutonic formations--minerals in granite, and their arrangement--graphic and porphyritic granite--mutual penetration of crystals of quartz and felspar--occasional minerals--syenite--syenitic, talcose, and schorly granites--eurite--passage of granite into trap--examples near christiania and in aberdeenshire--analogy in composition of trachyte and granite--granite veins in glen tilt, cornwall, the valorsine, and other countries--different composition of veins from main body of granite--metalliferous veins in strata near their junction with granite--apparent isolation of nodules of granite--quartz veins--whether plutonic rocks are ever overlying--their exposure at the surface due to denudation. the plutonic rocks may be treated of next in order, as they are most nearly allied to the volcanic class already considered. i have described, in the first chapter, these plutonic rocks as the unstratified division of the crystalline or hypogene formations, and have stated that they differ from the volcanic rocks, not only by their more crystalline texture, but also by the absence of tuffs and breccias, which are the products of eruptions at the earth's surface, or beneath seas of inconsiderable depth. they differ also by the absence of pores or cellular cavities, to which the expansion of the entangled gases gives rise in ordinary lava. from these and other peculiarities it has been inferred, that the granites have been formed at considerable depths in the earth, and have cooled and crystallized slowly under great pressure, where the contained gases could not expand. the volcanic rocks, on the contrary, although they also have risen up from below, have cooled from a melted state more rapidly upon or near the surface. from this hypothesis of the great depth at which the granites originated, has been derived the name of "plutonic rocks." the beginner will easily conceive that the influence of subterranean heat may extend downwards from the crater of every active volcano to a great depth below, perhaps several miles or leagues, and the effects which are produced deep in the bowels of the earth may, or rather must be, distinct; so that volcanic and plutonic rocks, each different in texture, and sometimes even in composition, may originate simultaneously, the one at the surface, the other far beneath it. by some writers, all the rocks now under consideration have been comprehended under the name of granite, which is, then, understood to embrace a large family of crystalline and compound rocks, usually found underlying all other formations; whereas we have seen that trap very commonly overlies strata of different ages. granite often preserves a very uniform character throughout a wide range of territory, forming hills of a peculiar rounded form, usually clad with a scanty vegetation. the surface of the rock is for the most part in a crumbling state, and the hills are often surmounted by piles of stones like the remains of a stratified mass, as in the annexed figure, and sometimes like heaps of boulders, for which they have been mistaken. the exterior of these stones, originally quadrangular, acquires a rounded form by the action of air and water, for the edges and angles waste away more rapidly than the sides. a similar spherical structure has already been described as characteristic of basalt and other volcanic formations, and it must be referred to analogous causes, as yet but imperfectly understood. [illustration: fig. . mass of granite near the sharp tor, cornwall.] although it is the general peculiarity of granite to assume no definite shapes, it is nevertheless occasionally subdivided by fissures, so as to assume a cuboidal, and even a columnar, structure. examples of these appearances may be seen near the land's end, in cornwall. (see figure.) [illustration: fig. . granite having a cuboidal and rude columnar structure, land's end, cornwall.] the plutonic formations also agree with the volcanic, in having veins or ramifications proceeding from central masses into the adjoining rocks, and causing alterations in these last, which will be presently described. they also resemble trap in containing no organic remains; but they differ in being more uniform in texture, whole mountain masses of indefinite extent appearing to have originated under conditions precisely similar. they also differ in never being scoriaceous or amygdaloidal, and never forming a porphyry with an uncrystalline base, or alternating with tuffs. nor do they form conglomerates, although there is sometimes an insensible passage from a fine to a coarse-grained granite, and occasionally patches of a fine texture are imbedded in a coarser variety. [illustration: fig. . gneiss. (see description, p. .)] felspar, quartz, and mica are usually considered as the minerals essential to granite, the felspar being most abundant in quantity, and the proportion of quartz exceeding that of mica. these minerals are united in what is termed a confused crystallization; that is to say, there is no regular arrangement of the crystals in granite, as in gneiss (see fig. .), except in the variety termed graphic granite, which occurs mostly in granitic veins. this variety is a compound of felspar and quartz, so arranged as to produce an imperfect laminar structure. the crystals of felspar appear to have been first formed, leaving between them the space now occupied by the darker-coloured quartz. this mineral, when a section is made at right angles to the alternate plates of felspar and quartz, presents broken lines, which have been compared to hebrew characters. [ illustrations: graphic granite. fig. . section parallel to the laminæ. fig. . section transverse to the laminæ.] as a general rule, quartz, in a compact or amorphous state, forms a vitreous mass, serving as the base in which felspar and mica have crystallized; for although these minerals are much more fusible than silex, they have often imprinted their shapes upon the quartz. this fact, apparently so paradoxical, has given rise to much ingenious speculation. we should naturally have anticipated that, during the cooling of the mass, the flinty portion would be the first to consolidate; and that the different varieties of felspar, as well as garnets and tourmalines, being more easily liquefied by heat, would be the last. precisely the reverse has taken place in the passage of most granitic aggregates from a fluid to a solid state, crystals of the more fusible minerals being found enveloped in hard, transparent, glassy quartz, which has often taken very faithful casts of each, so as to preserve even the microscopically minute striations on the surface of prisms of tourmaline. various explanations of this phenomenon have been proposed by mm. de beaumont, fournet, and durocher. they refer to m. gaudin's experiments on the fusion of quartz, which show that silex, as it cools, has the property of remaining in a viscous state, whereas alumina never does. this "gelatinous flint" is supposed to retain a considerable degree of plasticity long after the granitic mixture has acquired a low temperature; and m. e. de beaumont suggests, that electric action may prolong the duration of the viscosity of silex. occasionally, however, we find the quartz and felspar mutually imprinting their forms on each other, affording evidence of the simultaneous crystallization of both.[ -a] [illustration: fig. . porphyritic granite. land's end, cornwall.] _porphyritic granite._--this name has been sometimes given to that variety in which large crystals of felspar, sometimes more than inches in length, are scattered through an ordinary base of granite. an example of this texture may be seen in the granite of the land's end, in cornwall (fig. .). the two larger prismatic crystals in this drawing represent felspar, smaller crystals of which are also seen, similar in form, scattered through the base. in this base also appear black specks of mica, the crystals of which have a more or less perfect hexagonal outline. the remainder of the mass is quartz, the translucency of which is strongly contrasted to the opaqueness of the white felspar and black mica. but neither the transparency of the quartz, nor the silvery lustre of the mica, can be expressed in the engraving. the uniform mineral character of large masses of granite seems to indicate that large quantities of the component elements were thoroughly mixed up together, and then crystallized under precisely similar conditions. there are, however, many accidental, or "occasional," minerals, as they are termed, which belong to granite. among these black schorl or tourmaline, actinolite, zircon, garnet, and fluor spar, are not uncommon; but they are too sparingly dispersed to modify the general aspect of the rock. they show, nevertheless, that the ingredients were not everywhere exactly the same; and a still greater variation may be traced in the ever-varying proportions of the felspar, quartz, and mica. _syenite._--when hornblende is the substitute for mica, which is very commonly the case, the rock becomes syenite: so called from the celebrated ancient quarries of syene in egypt. it has all the appearance of ordinary granite, except when mineralogically examined in hand specimens, and is fully entitled to rank as a geological member of the same plutonic family as granite. syenite, however, after maintaining the granitic character throughout extensive regions, is not uncommonly found to lose its quartz, and to pass insensibly into syenitic greenstone, a rock of the trap family. werner considered syenite as a binary compound of felspar and hornblende, and regarded quartz as merely one of its occasional minerals. _syenitic-granite._--the quadruple compound of quartz, felspar, mica, and hornblende, may be so termed. this rock occurs in scotland and in guernsey. _talcose granite_, or protogine of the french, is a mixture of felspar, quartz, and talc. it abounds in the alps, and in some parts of cornwall, producing by its decomposition the china clay, more than , tons of which are annually exported from that country for the potteries.[ -a] _schorl rock, and schorly granite._--the former of these is an aggregate of schorl, or tourmaline, and quartz. when felspar and mica are also present, it may be called schorly granite. this kind of granite is comparatively rare. _eurite._--a rock in which all the ingredients of granite are blended into a finely granular mass. crystals of quartz and mica are sometimes scattered through the base of eurite. _pegmatite._--a name given by french writers to a variety of granite; a granular mixture of quartz and felspar; frequent in granite veins; passes into graphic granite. all these granites pass into certain kinds of trap, a circumstance which affords one of many arguments in favour of what is now the prevailing opinion, that the granites are also of igneous origin. the contrast of the most crystalline form of granite, to that of the most common and earthy trap, is undoubtedly great; but each member of the volcanic class is capable of becoming porphyritic, and the base of the porphyry may be more and more crystalline, until the mass passes to the kind of granite most nearly allied in mineral composition. the minerals which constitute alike the granitic and volcanic rocks consist, almost exclusively, of seven elements, namely, silica, alumina, magnesia, lime, soda, potash, and iron; and these may sometimes exist in about the same proportions in a porous lava, a compact trap, or a crystalline granite. it may perhaps be found, on farther examination--for on this subject we have yet much to learn--that the presence of these elements in certain proportions is more favourable than in others to their assuming a crystalline or true granitic structure; but it is also ascertained by experiment, that the same materials may, under different circumstances, form very different rocks. the same lava, for example, may be glassy, or scoriaceous, or stony, or porphyritic, according to the more or less rapid rate at which it cools; and some trachytes and syenitic-greenstones may doubtless form granite and syenite, if the crystallization take place slowly. it has also been suggested that the peculiar nature and structure of granite may be due to its retaining in it that water which is seen to escape from lavas when they cool slowly, and consolidate in the atmosphere. boutigny's experiments have shown that melted matter, at a white heat, requires to have its temperature lowered before it can vapourize water; and such discoveries, if they fail to explain the manner in which granites have been formed, serve at least to remind us of the entire distinctness of the conditions under which plutonic and volcanic rocks must be produced.[ -a] it would be easy to multiply examples and authorities to prove the gradation of the granitic into the trap rocks. on the western side of the fiord of christiania, in norway, there is a large district of trap, chiefly greenstone-porphyry, and syenitic-greenstone, resting on fossiliferous strata. to this, on its southern limit, succeeds a region equally extensive of syenite, the passage from the volcanic to the plutonic rock being so gradual that it is impossible to draw a line of demarcation between them. "the ordinary granite of aberdeenshire," says dr. macculloch, "is the usual ternary compound of quartz, felspar, and mica; but sometimes hornblende is substituted for the mica. but in many places a variety occurs which is composed simply of felspar and hornblende; and in examining more minutely this duplicate compound, it is observed in some places to assume a fine grain, and at length to become undistinguishable from the greenstones of the trap family. it also passes in the same uninterrupted manner into a basalt, and at length into a soft claystone, with a schistose tendency on exposure, in no respect differing from those of the trap islands of the western coast."[ -b] the same author mentions, that in shetland, a granite composed of hornblende, mica, felspar, and quartz, graduates in an equally perfect manner into basalt.[ -c] in hungary there are varieties of trachyte, which, geologically speaking, are of modern origin, in which crystals, not only of mica, but of quartz, are common, together with felspar and hornblende. it is easy to conceive how such volcanic masses may, at a certain depth from the surface, pass downwards into granite. [ illustrations: fig. . fig. . junction of granite and argillaceous schist in glen tilt. (macculloch.)[ -a]] i have already hinted at the close analogy in the forms of certain granitic and trappean veins; and it will be found that strata penetrated by plutonic rocks have suffered changes very similar to those exhibited near the contact of volcanic dikes. thus, in glen tilt, in scotland, alternating strata of limestone and argillaceous schist come in contact with a mass of granite. the contact does not take place as might have been looked for, if the granite had been formed there before the strata were deposited, in which case the section would have appeared as in fig. .; but the union is as represented in fig. ., the undulating outline of the granite intersecting different strata, and occasionally intruding itself in tortuous veins into the beds of clay-slate and limestone, from which it differs so remarkably in composition. the limestone is sometimes changed in character by the proximity of the granitic mass or its veins, and acquires a more compact texture, like that of hornstone or chert, with a splintery fracture, effervescing feebly with acids. the annexed diagram (fig. .) represents another junction, in the same district, where the granite sends forth so many veins as to reticulate the limestone and schist, the veins diminishing towards their termination to the thickness of a leaf of paper or a thread. in some places fragments of granite appear entangled, as it were, in the limestone, and are not visibly connected with any larger mass; while sometimes, on the other hand, a lump of the limestone is found in the midst of the granite. the ordinary colour of the limestone of glen tilt is lead blue, and its texture large-grained and highly crystalline; but where it approximates to the granite, particularly where it is penetrated by the smaller veins, the crystalline texture disappears, and it assumes an appearance exactly resembling that of hornstone. the associated argillaceous schist often passes into hornblende slate, where it approaches very near to the granite.[ -b] [illustration: fig. . junction of granite and limestone in glen tilt. (macculloch.) _a._ granite. _b._ limestone. _c._ blue argillaceous schist.] the conversion of the limestone in these and many other instances into a siliceous rock, effervescing slowly with acids, would be difficult of explanation, were it not ascertained that such limestones are always impure, containing grains of quartz, mica, or felspar disseminated through them. the elements of these minerals, when the rock has been subjected to great heat, may have been fused, and so spread more uniformly through the whole mass. [illustration: fig. . granite veins traversing clay slate. table mountain, cape of good hope.[ -a]] in the plutonic, as in the volcanic rocks, there is every gradation from a tortuous vein to the most regular form of a dike, such as intersect the tuffs and lavas of vesuvius and etna. dikes of granite may be seen, among other places, on the southern flank of mount battock, one of the grampians, the opposite walls sometimes preserving an exact parallelism for a considerable distance. as a general rule, however, granite veins in all quarters of the globe are more sinuous in their course than those of trap. they present similar shapes at the most northern point of scotland, and the southernmost extremity of africa, as the annexed drawings will show. it is not uncommon for one set of granite veins to intersect another; and sometimes there are three sets, as in the environs of heidelberg, where the granite on the banks of the river necker is seen to consist of three varieties, differing in colour, grain, and various peculiarities of mineral composition. one of these, which is evidently the second in age, is seen to cut through an older granite; and another, still newer, traverses both the second and the first. in shetland there are two kinds of granite. one of them, composed of hornblende, mica, felspar, and quartz, is of a dark colour, and is seen underlying gneiss. the other is a red granite, which penetrates the dark variety everywhere in veins.[ -a] [illustration: fig. . granite veins traversing gneiss, cape wrath. (macculloch.)[ -b]] [illustration: fig. . granite veins traversing gneiss at cape wrath, in scotland. (macculloch.)] the accompanying sketches will explain the manner in which granite veins often ramify and cut each other (figs. . and .). they represent the manner in which the gneiss at cape wrath, in sutherlandshire, is intersected by veins. their light colour, strongly contrasted with that of the hornblende-schist, here associated with the gneiss, renders them very conspicuous. granite very generally assumes a finer grain, and undergoes a change in mineral composition, in the veins which it sends into contiguous rocks. thus, according to professor sedgwick, the main body of the cornish granite is an aggregate of mica, quartz, and felspar; but the veins are sometimes without mica, being a granular aggregate of quartz and felspar. in other varieties quartz prevails to the almost entire exclusion both of felspar and mica; in others, the mica and quartz both disappear, and the vein is simply composed of white granular felspar.[ -c] fig. . is a sketch of a group of granite veins in cornwall, given by messrs. von oeynhausen and von dechen.[ -a] the main body of the granite here is of a porphyritic appearance, with large crystals of felspar; but in the veins it is fine-grained, and without these large crystals. the general height of the veins is from to feet, but some are much higher. [illustration: fig. . granite veins passing through hornblende slate, carnsilver cove, cornwall.] in the valorsine, a valley not far from mont blanc in switzerland, an ordinary granite, consisting of felspar, quartz, and mica, sends forth veins into a talcose gneiss (or stratified protogine), and in some places lateral ramifications are thrown off from the principal veins at right angles (see fig. .), the veins, especially the minute ones, being finer grained than the granite in mass. [illustration: fig. . veins of granite in talcose gneiss. (l. a. necker.)] it is here remarked, that the schist and granite, as they approach, seem to exercise a reciprocal influence on each other, for both undergo a modification of mineral character. the granite, still remaining unstratified, becomes charged with green particles; and the talcose gneiss assumes a granitiform structure without losing its stratification.[ -b] professor keilhau drew my attention to several localities in the country near christiania, where the mineral character of gneiss appears to have been affected by a granite of much newer origin, for some distance from the point of contact. the gneiss, without losing its laminated structure, seems to have become charged with a larger quantity of felspar, and that of a redder colour, than the felspar usually belonging to the gneiss of norway. granite, syenite, and those porphyries which have a granitiform structure, in short all plutonic rocks, are frequently observed to contain metals, at or near their junction with stratified formations. on the other hand, the veins which traverse stratified rocks are, as a general law, more metalliferous near such junctions than in other positions. hence it has been inferred that these metals may have been spread in a gaseous form through the fused mass, and that the contact of another rock, in a different state of temperature, or sometimes the existence of rents in other rocks in the vicinity, may have caused the sublimation of the metals.[ -a] there are many instances, as at markerud, near christiania, in norway, where the strike of the beds has not been deranged throughout a large area by the intrusion of granite, both in large masses and in veins. this fact is considered by some geologists to militate against the theory of the forcible injection of granite in a fluid state. but it may be stated in reply, that ramifying dikes of trap, which almost all now admit to have been once fluid, pass through the same fossiliferous strata, near christiania, without deranging their strike or dip.[ -b] [illustration: fig. . general view of junction of granite and schist of the valorsine. (l. a. necker.)] the real or apparent isolation of large or small masses of granite detached from the main body, as at _a b_, fig. ., and above, fig. ., and _a_, fig. ., has been thought by some writers to be irreconcilable with the doctrine usually taught respecting veins; but many of them may, in fact, be sections of root-shaped prolongations of granite; while, in other cases, they may in reality be detached portions of rock having the plutonic structure. for there may have been spots in the midst of the invaded strata, in which there was an assemblage of materials more fusible than the rest, or more fitted to combine readily into some form of granite. veins of pure quartz are often found in granite, as in many stratified rocks, but they are not traceable, like veins of granite or trap, to large bodies of rock of similar composition. they appear to have been cracks, into which siliceous matter was infiltered. such segregation, as it is called, can sometimes be shown to have clearly taken place long subsequently to the original consolidation of the containing rock. thus, for example, in the gneiss of tronstad strand, near drammen, in norway, the annexed section is seen on the beach. it appears that the alternating strata of whitish granitiform gneiss, and black hornblende-schist, were first cut through by a greenstone dike, about - / feet wide; then the crack _a b_ passed through all these rocks, and was filled up with quartz. the opposite walls of the vein are in some parts incrusted with transparent crystals of quartz, the middle of the vein being filled up with common opaque white quartz. [illustration: fig. . _a, b._ quartz vein passing through gneiss and greenstone, tronstad strand, near christiania.] [illustration: fig. . euritic porphyry alternating with primary fossiliferous strata, near christiania.] we have seen that the volcanic formations have been called overlying, because they not only penetrate others, but spread over them. mr. necker has proposed to call the granites the underlying igneous rocks, and the distinction here indicated is highly characteristic. it was indeed supposed by some of the earlier observers, that the granite of christiania, in norway, was intercalated in mountain masses between the primary or paleozoic strata of that country, so as to overlie fossiliferous shale and limestone. but although the granite sends veins into these fossiliferous rocks, and is decidedly posterior in origin, its actual superposition in mass has been disproved by professor keilhau, whose observations on this controverted point i had opportunities in of verifying. there are, however, on a smaller scale, certain beds of euritic porphyry, some a few feet, others many yards in thickness, which pass into granite, and deserve perhaps to be classed as plutonic rather than trappean rocks, which may truly be described as interposed conformably between fossiliferous strata, as the porphyries (_a c_, fig. .), which divide the bituminous shales and argillaceous limestones, _f f_. but some of these same porphyries are partially unconformable, as _b_, and may lead us to suspect that the others also, notwithstanding their appearance of interstratification, have been forcibly injected. some of the porphyritic rocks above mentioned are highly quartzose, others very felspathic. in proportion as the masses are more voluminous, they become more granitic in their texture, less conformable, and even begin to send forth veins into contiguous strata. in a word, we have here a beautiful illustration of the intermediate gradations between volcanic and plutonic rocks, not only in their mineralogical composition and structure, but also in their relations of position to associated formations. if the term overlying can in this instance be applied to a plutonic rock, it is only in proportion as that rock begins to acquire a trappean aspect. it has been already hinted that the heat, which in every active volcano extends downwards to indefinite depths, must produce simultaneously very different effects near the surface, and far below it; and we cannot suppose that rocks resulting from the crystallizing of fused matter under a pressure of several thousand feet, much less miles, of the earth's crust can resemble those formed at or near the surface. hence the production at great depths of a class of rocks analogous to the volcanic, and yet differing in many particulars, might almost have been predicted, even had we no plutonic formations to account for. how well these agree, both in their positive and negative characters, with the theory of their deep subterranean origin, the student will be able to judge by considering the descriptions already given. it has, however, been objected, that if the granitic and volcanic rocks were simply different parts of one great series, we ought to find in mountain chains volcanic dikes passing upwards into lava, and downwards into granite. but we may answer, that our vertical sections are usually of small extent; and if we find in certain places a transition from trap to porous lava, and in others a passage from granite to trap, it is as much as could be expected of this evidence. the prodigious extent of denudation which has been already demonstrated to have occurred at former periods, will reconcile the student to the belief that crystalline rocks of high antiquity, although deep in the earth's crust when originally formed, may have become uncovered and exposed at the surface. their actual elevation above the sea may be referred to the same causes to which we have attributed the upheaval of marine strata, even to the summits of some mountain chains. but to these and other topics, i shall revert when speaking, in the next chapter, of the relative ages of different masses of granite. footnotes: [ -a] bulletin, d sèrie, iv. .; and archiac, hist. des progrès de geol., i. . [ -a] boase on primary geology, p. . [ -a] bulletin, vol. iv., d ser., pp. . and . [ -b] syst. of geol., vol. i. p. . [ -c] ibid., p. . [ -a] geol. trans., st series, vol. iii. pl. . [ -b] macculloch, geol. trans., vol. iii. p. . [ -a] capt. b. hall, trans. roy. soc. edin., vol. vii. [ -a] macculloch, syst. of geol., vol. i. p. . [ -b] western islands, pl. . [ -c] on geol. of cornwall, camb. trans. vol. i. p. . [ -a] phil. mag. and annals, no. . new series, march, . [ -b] necker, sur la val. de valorsine, mém. de la soc. de phys. de génève, . i visited, in , the spot referred to in fig. . [ -a] necker, proceedings of geol. soc., no. . p. . [ -b] see keilhau's gæa norvegica; christiania, . chapter xxxiv. on the different ages of the plutonic rocks. difficulty in ascertaining the precise age of a plutonic rock--test of age by relative position--test by intrusion and alteration--test by mineral composition--test by included fragments--recent and pliocene plutonic rocks, why invisible--tertiary plutonic rocks in the andes--granite altering cretaceous rocks--granite altering lias in the alps and in skye--granite of dartmoor altering carboniferous strata--granite of the old red sandstone period--syenite altering silurian strata in norway--blending of the same with gneiss--most ancient plutonic rocks--granite protruded in a solid form--on the probable age of the granites of arran, in scotland. when we adopt the igneous theory of granite, as explained in the last chapter, and believe that different plutonic rocks have originated at successive periods beneath the surface of the planet, we must be prepared to encounter greater difficulty in ascertaining the precise age of such rocks, than in the case of volcanic and fossiliferous formations. we must bear in mind, that the evidence of the age of each contemporaneous volcanic rock was derived, either from lavas poured out upon the ancient surface, whether in the sea or in the atmosphere, or from tuffs and conglomerates, also deposited at the surface, and either containing organic remains themselves, or intercalated between strata containing fossils. but all these tests fail when we endeavour to fix the chronology of a rock which has crystallized from a state of fusion in the bowels of the earth. in that case, we are reduced to the following tests; st, relative position; dly, intrusion, and alteration of the rocks in contact; dly, mineral characters; thly, included fragments. _test of age by relative position._--unaltered fossiliferous strata of every age are met with reposing immediately on plutonic rocks; as at christiania, in norway, where the newer pliocene deposits rest on granite; in auvergne, where the freshwater eocene strata, and at heidelberg, on the rhine, where the new red sandstone, occupy a similar place. in all these, and similar instances, inferiority in position is connected with the superior antiquity of granite. the crystalline rock was solid before the sedimentary beds were superimposed, and the latter usually contain in them rounded pebbles of the subjacent granite. _test by intrusion and alteration._--but when plutonic rocks send veins into strata, and alter them near the point of contact, in the manner before described (p. .), it is clear that, like intrusive traps, they are newer than the strata which they invade and alter. examples of the application of this test will be given in the sequel. _test by mineral composition._--notwithstanding a general uniformity in the aspect of plutonic rocks, we have seen in the last chapter that there are many varieties, such as syenite, talcose granite, and others. one of these varieties is sometimes found exclusively prevailing throughout an extensive region, where it preserves a homogeneous character; so that having ascertained its relative age in one place, we can easily recognize its identity in others, and thus determine from a single section the chronological relations of large mountain masses. having observed, for example, that the syenitic granite of norway, in which the mineral called zircon abounds, has altered the silurian strata wherever it is in contact, we do not hesitate to refer other masses of the same zircon-syenite in the south of norway to the same era. some have imagined that the age of different granites might, to a great extent, be determined by their mineral characters alone; syenite, for instance, or granite with hornblende, being more modern than common or micaceous granite. but modern investigations have proved these generalizations to have been premature. the syenitic granite of norway already alluded to may be of the same age as the silurian strata, which it traverses and alters, or may belong to the old red sandstone period; whereas the granite of dartmoor, although consisting of mica, quartz, and felspar, is newer than the coal. (see p. .) _test by included fragments._--this criterion can rarely be of much importance, because the fragments involved in granite are usually so much altered, that they cannot be referred with certainty to the rocks whence they were derived. in the white mountains, in north america, according to professor hubbard, a granite vein traversing granite, contains fragments of slate and trap, which must have fallen into the fissure when the fused materials of the vein were injected from below[ -a], and thus the granite is shown to be newer than certain superficial slaty and trappean formations. _recent and pliocene plutonic rocks, why invisible._--the explanation already given in the th and in the last chapter, of the probable relation of the plutonic to the volcanic formations, will naturally lead the reader to infer, that rocks of the one class can never be produced at or near the surface without some members of the other being formed below simultaneously, or soon afterwards. it is not uncommon for lava-streams to require more than ten years to cool in the open air; and where they are of great depth, a much longer period. the melted matter poured from jorullo, in mexico, in the year , which accumulated in some places to the height of feet, was found to retain a high temperature half a century after the eruption.[ -b] we may conceive, therefore, that great masses of subterranean lava may remain in a red-hot or incandescent state in the volcanic foci for immense periods, and the process of refrigeration may be extremely gradual. sometimes, indeed, this process may be retarded for an indefinite period, by the accession of fresh supplies of heat; for we find that the lava in the crater of stromboli, one of the lipari islands, has been in a state of constant ebullition for the last two thousand years; and we may suppose this fluid mass to communicate with some caldron or reservoir of fused matter below. in the isle of bourbon, also, where there has been an emission of lava once in every two years for a long period, the lava below can scarcely fail to have been permanently in a state of liquefaction. if then it be a reasonable conjecture, that about volcanic eruptions occur in the course of every century, either above the waters of the sea or beneath them[ -a], it will follow, that the quantity of plutonic rock generated, or in progress during the recent epoch, must already have been considerable. but as the plutonic rocks originate at some depth in the earth's crust, they can only be rendered accessible to human observation, by subsequent upheaval and denudation. between the period when a plutonic rock crystallizes in the subterranean regions, and the era of its protrusion at any single point of the surface, one or two geological periods must usually intervene. hence, we must not expect to find the recent or newer pliocene granites laid open to view, unless we are prepared to assume that sufficient time has elapsed since the commencement of the newer pliocene period for great upheaval and denudation. a plutonic rock, therefore, must, in general, be of considerable antiquity relatively to the fossiliferous and volcanic formations, before it becomes extensively visible. as we know that the upheaval of land has been sometimes accompanied in south america by volcanic eruptions and the emission of lava, we may conceive the more ancient plutonic rocks to be forced upwards to the surface by the newer rocks of the same class formed successively below,--subterposition in the plutonic, like superposition in the sedimentary rocks, being usually characteristic of a newer origin. in the accompanying diagram (fig. .), an attempt is made to show the inverted order in which sedimentary and plutonic formations may occur in the earth's crust. the oldest plutonic rock, no. i., has been upheaved at successive periods until it has become exposed to view in a mountain-chain. this protrusion of no. i. has been caused by the igneous agency which produced the newer plutonic rocks nos. ii. iii. and iv. part of the primary fossiliferous strata, no. ., have also been raised to the surface by the same gradual process. it will be observed that the recent _strata_ no. ., and the recent _granite_ or plutonic rock no. iv., are the most remote from each other in position, although of contemporaneous date. according to this hypothesis, the convulsions of many periods will be required before _recent_ granite will be upraised so as to form the highest ridges and central axes of mountain-chains. during that time the _recent_ strata no. . might be covered by a great many newer sedimentary formations. [illustration: fig. . diagram showing the relative position which the plutonic and sedimentary formations of different ages may occupy. i. primary plutonic. . recent strata. ii. secondary plutonic. . tertiary strata. iii. tertiary plutonic. . secondary strata. iv. recent plutonic. . primary fossiliferous strata. the metamorphic rocks are not indicated in this diagram; but the student will infer, from what has been said in chap. xxxii., that some portions of the stratified formations nos. . and . invaded by granite will have become metamorphic.] _eocene granite and plutonic rocks._--in a former part of this volume (p. .), the great nummulitic formation of the alps and pyrenees was referred to the eocene period, and it follows that those vast movements which have raised fossiliferous rocks from the level of the sea to the height of more than , feet above its level have taken place since the commencement of the tertiary epoch. here, therefore, if anywhere, we might expect to find hypogene formations of eocene date breaking out in the central axis or most disturbed region of the loftiest chain in europe. accordingly, in the swiss alps, even the _flysch_, or upper portion of the nummulitic series, has been occasionally invaded by plutonic rocks, and converted into crystalline schists of the hypogene class. there can be little doubt that even the talcose granite of mont blanc itself has been in a fused or pasty state since the _flysch_ was deposited at the bottom of the sea; and the question as to its age is not so much whether it be a secondary or tertiary granite, as whether it should be assigned to the eocene or miocene epoch. great upheaving movements have been experienced in the region of the andes, during the post-pliocene period. in some part, therefore, of this chain, we may expect to discover tertiary plutonic rocks laid open to view. what we already know of the structure of the chilian andes seems to realize this expectation. in a transverse section, examined by mr. darwin, between valparaiso and mendoza, the cordillera was found to consist of two separate and parallel chains, formed of sedimentary rocks of different ages, the strata in both resting on plutonic rocks, by which they have been altered. in the western or oldest range, called the peuquenes, are black calcareous clay-slates, rising to the height of nearly , feet above the sea, in which are shells of the genera _gryphæa_, _turritella_, _terebratula_, and _ammonite_. these rocks are supposed to be of the age of the central parts of the secondary series of europe. they are penetrated and altered by dikes and mountain masses of a plutonic rock, which has the texture of ordinary granite, but rarely contains quartz, being a compound of albite and hornblende. the second or eastern chain consists chiefly of sandstones and conglomerates, of vast thickness, the materials of which are derived from the ruins of the western chain. the pebbles of the conglomerates are, for the most part, rounded fragments of the fossiliferous slates before mentioned. the resemblance of the whole series to certain tertiary deposits on the shores of the pacific, not only in mineral character, but in the imbedded lignite and silicified woods, leads to the conjecture that they also are tertiary. yet these strata are not only associated with trap rocks and volcanic tuffs, but are also altered by a granite consisting of quartz, felspar, and talc. they are traversed, moreover, by dikes of the same granite, and by numerous veins of iron, copper, arsenic, silver, and gold; all of which can be traced to the underlying granite.[ -a] we have, therefore, strong ground to presume that the plutonic rock, here exposed on a large scale in the chilian andes, is of later date than certain tertiary formations. but the theory adopted in this work of the subterranean origin of the hypogene formations would be untenable, if the supposed fact here alluded to, of the appearance of tertiary granite at the surface was not a rare exception to the general rule. a considerable lapse of time must intervene between the formation in the nether regions of plutonic and metamorphic rocks, and their emergence at the surface. for a long series of subterranean movements must occur before such rocks can be uplifted into the atmosphere or the ocean; and, before they can be rendered visible to man, some strata which previously covered them must usually have been stripped off by denudation. we know that in the bay of baiæ, in , in cutch in , and on several occasions in peru and chili, since the commencement of the present century, the permanent upheaval or subsidence of land has been accompanied by the simultaneous emission of lava at one or more points in the same volcanic region. from these and other examples it may be inferred that the rising or sinking of the earth's crust, operations by which sea is converted into land, and land into sea, are a part only of the consequences of subterranean igneous action. it can scarcely be doubted that this action consists, in a great degree, of the baking, and occasionally the liquefaction, of rocks, causing them to assume, in some cases a larger, in others a smaller volume than before the application of heat. it consists also in the generation of gases, and their expansion by heat, and the injection of liquid matter into rents formed in superincumbent rocks. the prodigious scale on which these subterranean causes have operated in sicily since the deposition of the newer pliocene strata will be appreciated, when we remember that throughout half the surface of that island such strata are met with, raised to the height of from to that of and even feet above the level of the sea. in the same island also the older rocks which are contiguous to these marine tertiary strata must have undergone, within the same period, a similar amount of upheaval. the like observations may be extended to nearly the whole of europe, for, since the commencement of the eocene period, the entire european area, including some of the central and very lofty portions of the alps themselves, as i have elsewhere shown[ -a], has, with the exception of a few districts, emerged from the deep to its present altitude; and even those tracts, which were already dry land before the eocene era, have almost everywhere acquired additional height. a large amount of subsidence has also occurred during the same period, so that the extent of the subterranean spaces which have either become the receptacles of sunken fragments of the earth's crust, or have been rendered capable of supporting other fragments at a much greater height than before, must be so great that they probably equal, if not exceed in volume, the entire continent of europe. we are entitled, therefore, to ask what amount of change of equivalent importance can be proved to have occurred in the earth's crust within an equal quantity of time anterior to the eocene epoch. they who contend for the more intense energy of subterranean causes in the remoter eras of the earth's history, may find it more difficult to give an answer to this question than they anticipated. the principal effect of volcanic action in the nether regions, during the tertiary period, seems to have consisted in the upheaval to the surface of hypogene formations of an age anterior to the carboniferous. the repetition of another series of movements, of equal violence, might upraise the plutonic and metamorphic rocks of many secondary periods; and if the same force should still continue to act, the next convulsions might bring up to the day the _tertiary_ and _recent_ hypogene rocks. in the course of such changes many of the existing sedimentary strata would suffer greatly by denudation, others might assume a metamorphic structure, or become melted down into plutonic and volcanic rocks. meanwhile the deposition of a vast thickness of new strata would not fail to take place during the upheaval and partial destruction of the older rocks. but i must refer the reader to the last chapter but one of this volume for a fuller explanation of these views. [illustration: fig. . block section.] _cretaceous period._--it will be shown in the next chapter that chalk, as well as lias, has been altered by granite in the eastern pyrenees. whether such granite be cretaceous or tertiary cannot easily be decided. suppose _b, c, d_, to be three members of the cretaceous series, the lowest of which, _b_, has been altered by the granite a, the modifying influence not having extended so far as _c_, or having but slightly affected its lowest beds. now it can rarely be possible for the geologist to decide whether the beds d existed at the time of the intrusion of a, and alteration of _b_ and _c_, or whether they were subsequently thrown down upon _c_. as some cretaceous rocks, however, have been raised to the height of more than feet in the pyrenees, we must not assume that plutonic formations of the same age may not have been brought up and exposed by denudation, at the height of or feet on the flanks of that chain. _period of oolite and lias._--in the department of the hautes alpes, in france, near vizille, m. elie de beaumont traced a black argillaceous limestone, charged with belemnites, to within a few yards of a mass of granite. here the limestone begins to put on a granular texture, but is extremely fine-grained. when nearer the junction it becomes grey, and has a saccharoid structure. in another locality, near champoleon, a granite composed of quartz, black mica, and rose-coloured felspar, is observed partly to overlie the secondary rocks, producing an alteration which extends for about feet downwards, diminishing in the beds which lie farthest from the granite. (see fig. .) in the altered mass the argillaceous beds are hardened, the limestone is saccharoid, the grits quartzose, and in the midst of them is a thin layer of an imperfect granite. it is also an important circumstance that near the point of contact, both the granite and the secondary rocks become metalliferous, and contain nests and small veins of blende, galena, iron, and copper pyrites. the stratified rocks become harder and more crystalline, but the granite, on the contrary, softer and less perfectly crystallized near the junction.[ -a] [illustration: fig. . junction of granite with jurassic or oolite strata in the alps, near champoleon.] although the granite is incumbent in the above section (fig. .), we cannot assume that it overflowed the strata, for the disturbances of the rocks are so great in this part of the alps that they seldom retain the position which they must originally have occupied. a considerable mass of syenite, in the isle of skye, is described by dr. macculloch as intersecting limestone and shale, which are of the age of the lias.[ -b] the limestone, which, at a greater distance from the granite, contains shells, exhibits no traces of them near its junction, where it has been converted into a pure crystalline marble.[ -c] at predazzo, in the tyrol, secondary strata, some of which are limestones of the oolitic period, have been traversed and altered by plutonic rocks, one portion of which is an augitic porphyry, which passes insensibly into granite. the limestone is changed into granular marble, with a band of serpentine at the junction.[ -d] _carboniferous period._--the granite of dartmoor, in devonshire, was formerly supposed to be one of the most ancient of the plutonic rocks, but is now ascertained to be posterior in date to the culm-measures of that county, which, from their position, and as containing true coal-plants, are regarded by professor sedgwick and sir r. murchison as members of the true carboniferous series. this granite, like the syenitic granite of christiania, has broken through the stratified formations without much changing their strike. hence, on the north-west side of dartmoor, the successive members of the culm-measures abut against the granite, and become metamorphic as they approach. these strata are also penetrated by granite veins, and plutonic dikes, called "elvans."[ -a] the granite of cornwall is probably of the same date, and, therefore, as modern as the carboniferous strata, if not much newer. _silurian period._--it has long been known that the granite near christiania, in norway, is of newer origin than the silurian strata of that region. von buch first announced, in , the discovery of its posteriority in date to limestones containing orthocerata and trilobites. the proofs consist in the penetration of granite veins into the shale and limestone, and the alteration of the strata, for a considerable distance from the point of contact, both of these veins and the central mass from which they emanate. (see p. .) von buch supposed that the plutonic rock alternated with the fossiliferous strata, and that large masses of granite were sometimes incumbent upon the strata; but this idea was erroneous, and arose from the fact that the beds of shale and limestone often dip towards the granite up to the point of contact, appearing as if they would pass under it in mass, as at _a_, fig. ., and then again on the opposite side of the same mountain, as at _b_, dip away from the same granite. when the junctions, however, are carefully examined, it is found that the plutonic rock intrudes itself in veins, and nowhere covers the fossiliferous strata in large overlying masses, as is so commonly the case with trappean formations.[ -b] [illustration: fig. . cross section.] now this granite, which is more modern than the silurian strata of norway, also sends veins in the same country into an ancient formation of gneiss; and the relations of the plutonic rock and the gneiss, at their junction, are full of interest when we duly consider the wide difference of epoch which must have separated their origin. [illustration: fig. . granite sending veins into silurian strata and gneiss,--christiania, norway.] the length of this interval of time is attested by the following facts:--the fossiliferous, or silurian beds, rest unconformably upon the truncated edges of the gneiss, the inclined strata of which had been disturbed and denuded before the sedimentary beds were superimposed (see fig. .). the signs of denudation are twofold; first, the surface of the gneiss is seen occasionally, on the removal of the newer beds, containing organic remains, to be worn and smoothed; secondly, pebbles of gneiss have been found in some of the transition strata. between the origin, therefore, of the gneiss and the granite there intervened, first, the period when the strata of gneiss were inclined; secondly, the period when they were denuded; thirdly, the period of the deposition of the transition deposits. yet the granite produced, after this long interval, is often so intimately blended with the ancient gneiss, at the point of junction, that it is impossible to draw any other than an arbitrary line of separation between them; and where this is not the case, tortuous veins of granite pass freely through gneiss, ending sometimes in threads, as if the older rock had offered no resistance to their passage. it seems necessary, therefore, to conceive that the gneiss was softened and more or less melted when penetrated by the granite. but had such junctions alone been visible, and had we not learnt, from other sections, how long a period elapsed between the consolidation of the gneiss and the injection of this granite, we might have suspected that the gneiss was scarcely solidified, or had not yet assumed its complete metamorphic character, when invaded by the plutonic rock. from this example we may learn how impossible it is to conjecture whether certain granites in scotland, and other countries, which send veins into gneiss and other metamorphic rocks, are primary, or whether they may not belong to some secondary or tertiary period. _oldest granites._--it is not half a century since the doctrine was very general that all granitic rocks were _primitive_, that is to say, that they originated before the deposition of the first sedimentary strata, and before the creation of organic beings (see above, p. .). but so greatly are our views now changed, that we find it no easy task to point out a single mass of granite demonstrably more ancient than all the known fossiliferous deposits. could we discover some lower cambrian strata resting immediately on granite, there being no alterations at the point of contact, nor any intersecting granitic veins, we might then affirm the plutonic rock to have originated before the oldest known fossiliferous strata. still it would be presumptuous to suppose that when a small part only of the globe has been investigated, we are acquainted with the oldest fossiliferous strata in the crust of our planet. even when these are found, we cannot assume that there never were any antecedent strata containing organic remains, which may have become metamorphic. if we find pebbles of granite in a conglomerate of the lower cambrian system, we may then feel assured that the parent granite was formed before the lower cambrian formation. but if the incumbent strata be merely silurian or upper cambrian, the fundamental granite, although of high antiquity, may be posterior in date to _known_ fossiliferous formations. _protrusion of solid granite._--in part of sutherlandshire, near brora, common granite, composed of felspar, quartz, and mica, is in immediate contact with oolitic strata, and has clearly been elevated to the surface at a period subsequent to the deposition of those strata.[ -a] professor sedgwick and sir r. murchison conceive that this granite has been upheaved in a solid form; and that in breaking through the submarine deposits, with which it was not perhaps originally in contact, it has fractured them so as to form a breccia along the line of junction. this breccia consists of fragments of shale, sandstone, and limestone, with fossils of the oolite, all united together by a calcareous cement. the secondary strata, at some distance from the granite, are but slightly disturbed, but in proportion to their proximity the amount of dislocation becomes greater. if we admit that solid hypogene rocks, whether stratified or unstratified, have in such cases been driven upwards so as to pierce through yielding sedimentary deposits, we shall be enabled to account for many geological appearances otherwise inexplicable. thus, for example, at weinböhla and hohnstein, near meissen, in saxony, a mass of granite has been observed covering strata of the cretaceous and oolitic periods for the space of between and yards square. it appears clearly from a recent memoir of dr. b. cotta on this subject[ -b], that the granite was thrust into its actual position when solid. there are no intersecting veins at the junction--no alteration as if by heat, but evident signs of rubbing, and a breccia in some places, in which pieces of granite are mingled with broken fragments of the secondary rocks. as the granite overhangs both the lias and chalk, so the lias is in some places bent over strata of the cretaceous era. _relative age of the granites of arran._--in this island, the largest in the firth of clyde, being twenty miles in length from north to south, the four great classes of rocks, the fossiliferous, volcanic, plutonic, and metamorphic, are all conspicuously displayed within a very small area, and with their peculiar characters strongly contrasted. in the north of the island the granite rises to the height of nearly feet above the sea, terminating in mountainous peaks. (see section, fig. .) on the flanks of the same mountains are chloritic-schists, blue roofing-slate, and other rocks of the metamorphic order (no. .), into which the granite (no. .) sends veins. this granite, therefore, is newer than the hypogene schists (no. .), which it penetrates. these schists are highly inclined. upon them rest beds of conglomerate and sandstone (no. .), which are referable to the old red formation, to which succeed various shales and limestones (no. .) containing the fossils of the carboniferous period, upon which are other strata of sandstone and conglomerate (upper part of no. .), in which no fossils have been met with, which it is conjectured may belong to the new red sandstone period. all the preceding formations are cut through by the volcanic rocks (no. .), which consist of greenstone, basalt, pitchstone, claystone-porphyry, and other varieties. these appear either in the form of dikes, or in dense masses from to feet in thickness, overlying the strata (no. .). they sometimes pass into syenite of so crystalline a form, that it may rank as a plutonic formation; and in one region, at ploverfield, in glen cloy, a fine-grained granite ( . _a_) is seen associated with the trap formation, and sending veins into the sandstone or into the upper strata of no. . this interesting discovery of granite in the southern region of arran, at a point where it is separated from the northern mass of granite by a great thickness of secondary strata and overlying trap, was made by mr. l. a. necker of geneva, during his survey of arran in . we also learn from the recent investigations of prof. a. c. ramsay, that a similar fine-grained granite (no. . _b_) appears in the interior of the northern granitic district, forming the nucleus of it, and sending veins into the older coarse-grained granite (no. .). the trap dikes which penetrate the older granite are cut off, according to mr. ramsay, at the junction of the fine grained. it is not improbable that the granite (no. . _b_) may be of the same age as that of ploverfield (no. . _a_), and this again may belong to the same geological epoch as the trap formations (no. .). if there be any difference of date, it would seem that the fine-grained granite must be newer than the trappean rocks. but, on the other hand, the coarser granite (no. .) may be the oldest rock in arran, with the exception of the hypogene slates (no. .), into which it sends veins. [illustration: fig. . general section of arran from north to south. . metamorphic or hypogene schists, the oldest formations in arran. . coarse-grained granite sending veins into the schists, no. . . old red sandstone and conglomerate containing pebbles exclusively derived from the rocks, no ., without any intermixture of granitic fragments. . carboniferous strata and red sandstone (new red?). . trap, overlying and in dikes, passing occasionally into syenites of the plutonic class. . _a._ fine-grained granite, associated with the overlying trap, no. . . _b._ similar fine-grained granite, sending veins into the older granite, no. ., and cutting off the trappean dikes, _c_, _d_.[ -a]] an objection may perhaps at first be started to this conclusion, derived from the curious and striking fact, the importance of which was first emphatically pointed out by dr. macculloch, that no pebbles of granite occur in the conglomerates of the red sandstone in arran, although these conglomerates are several hundred feet in thickness, and lie at the foot of lofty granite mountains, which tower above them. as a general rule, all such aggregates of pebbles and sand are mainly composed of the wreck of pre-existing rocks occurring in the immediate vicinity. the total absence therefore of granitic pebbles has justly been a theme of wonder to those geologists who have successively visited arran, and they have carefully searched there, as i have done myself, to find an exception, but in vain. the rounded masses consist exclusively of quartz, chlorite-schist, and other members of the metamorphic series; nor in the newer conglomerates of no. . have any granitic fragments been discovered. are we then entitled to affirm that the coarse-grained granite (no. .), like the fine-grained variety (no. . _a_), is more modern than all the other rocks of the island? this we cannot assume at present, but we may confidently infer that when the various beds of sandstone and conglomerate were formed, no granite had reached the surface, or had been exposed to denudation in arran. it is clear that the crystalline schists were ground into sand and shingle when the strata no. . were deposited, and at that time the waves had never acted upon the granite, which now sends its veins into the schist. may we then conclude, that the schists suffered denudation before they were invaded by granite? this opinion, although not inadmissible, is by no means fully borne out by the evidence. for at the time when the old red sandstone originated, the metamorphic strata may have formed islands in the sea, as in fig. ., over which the breakers rolled, or from which torrents and rivers descended, carrying down gravel and sand. the plutonic rock or granite (b) may even then have been previously injected at a certain depth below, and yet may never have been exposed to denudation. [illustration: fig. . cross section.] as to the time and manner of the subsequent protrusion of the coarse-grained granite (no. .), this rock may have been thrust up bodily, in a solid form, during that long series of igneous operations which produced the trappean and plutonic formations (nos. ., . _a_, and . _b_). we have shown that these eruptions, whatever their date, were posterior to the deposition of all the fossiliferous strata of arran. we can also prove that subsequently both the granitic and trappean rocks underwent great aqueous denudation, which they probably suffered during their emergence from the sea. the fact is demonstrated by the abrupt truncation of numerous dikes, such as those at _c_, _d_, _e_, which are cut off on the surface of the granite and trap. the overlying trap also ceases very abruptly on approaching the boundary of the great hypogene region, and terminates in a steep escarpment facing towards it as at _f_, fig. . when in its original fluid state it could not have come thus suddenly to an end, but must have filled up the hollow now separating it from the hypogene rocks, had such a hollow then existed. this necessity of supposing that both the trap and the conglomerate once extended farther, and that veins such as _c_, _d_, fig. ., were once prolonged farther upwards, prepares us to believe that the whole of the northern granite may at one time have been covered by newer formations, under the pressure of which, before its protrusion, it assumed its highly crystalline texture. the theory of the protrusion in a solid form of the northern nucleus of granite is confirmed by the manner in which the hypogene slates (no. .) and the beds of conglomerate (no. .) dip away from it on all sides. in some places indeed the slates are inclined towards the granite, but this exception might have been looked for, because these hypogene strata have undergone disturbances at more than one geological epoch, and may at some points, perhaps, have their original order of position inverted. the high inclination, therefore, and the quâquâversal dip of the beds around the borders of the granitic boss, and the comparative horizontality of the fossiliferous strata in the southern part of the island, are facts which all accord with the hypothesis of a great amount of movement at that point where the granite is supposed to have been thrust up bodily, and where we may conceive it to have been distended laterally by the repeated injection of fresh supplies of melted materials.[ -a] footnotes: [ -a] silliman's journ., no. . p. . [ -b] see "principles," _index_, "jorullo." [ -a] "principles," _index_, "volcanic eruptions." [ -a] darwin, pp. . .; second edition, p. . [ -a] see map of europe and explanation, in principles, book i. [ -a] elie de beaumont, sur les montagnes de l'oisans, &c. mém. de la soc. d'hist. nat. de paris, tom. v. [ -b] see murchison, geol. trans., d series, vol. ii. part ii. pp. - . [ -c] western islands, vol. i. p. . plate ., figs. , . [ -d] von buch, annales de chimie, &c. [ -a] proceedings of geol. soc., vol. ii. p. . [ -b] see the gæa norvegica and other works of keilhau, with whom i examined this country. [ -a] murchison, geol. trans., d series, vol. ii. p. . [ -b] geognostische wanderungen, leipzig, . [ -a] in the above section i have attempted to represent the new discoveries made since , by mr. necker and mr. a. c. ramsay, in regard to the plutonic formations, . _a_, and . _b_. [ -a] for the geology of arran consult the works of drs. hutton and macculloch, the memoirs of messrs. von dechen and oeynhausen, that of professor sedgwick and sir r. murchison (geol. trans. d series), mr. l. a. necker's memoir, read to the royal soc. of edin. th april, , and mr. ramsay's geol. of arran, . i examined myself a large part of arran in . chapter xxxv. metamorphic rocks. general character of metamorphic rocks--gneiss--hornblende-schist-- mica-schist--clay-slate--quartzite--chlorite-schist--metamorphic limestone--alphabetical list and explanation of other rocks of this family--origin of the metamorphic strata--their stratification is real and distinct from cleavage--joints and slaty cleavage--supposed causes of these structures--how far connected with crystalline action. we have now considered three distinct classes of rocks: first, the aqueous, or fossiliferous; secondly, the volcanic; and, thirdly, the plutonic, or granitic; and we have now, lastly, to examine those crystalline (or hypogene) strata to which the name of _metamorphic_ has been assigned. the last-mentioned term expresses, as before explained, a theoretical opinion that such strata, after having been deposited from water, acquired, by the influence of heat and other causes, a highly crystalline texture. they who still question this opinion may call the rocks under consideration the stratified hypogene, or schistose hypogene formations. these rocks, when in their most characteristic or normal state, are wholly devoid of organic remains, and contain no distinct fragments of other rocks, whether rounded or angular. they sometimes break out in the central parts of narrow mountain chains, but in other cases extend over areas of vast dimensions, occupying, for example, nearly the whole of norway and sweden, where, as in brazil, they appear alike in the lower and higher grounds. in great britain, those members of the series which approach most nearly to granite in their composition, as gneiss, mica-schist, and hornblende-schist, are confined to the country north of the rivers forth and clyde. many attempts have been made to trace a general order of succession or superposition in the members of this family; gneiss, for example, having been often supposed to hold invariably a lower geological position than mica-schist. but although such an order may prevail throughout limited districts, it is by no means universal, nor even general, throughout the globe. to this subject, however, i shall again revert, in the last chapter of this volume, when the chronological relations of the metamorphic rocks are pointed out. the following may be enumerated as the principal members of the metamorphic class:--gneiss, mica-schist, hornblende-schist, clay-slate, chlorite-schist, hypogene or metamorphic limestone, and certain kinds of quartz-rock or quartzite. [illustration: fig. . fragment of gneiss, natural size; section at right angles to planes of stratification.] _gneiss._--the first of these, gneiss, may be called stratified granite, being formed of the same materials as granite, namely, felspar, quartz, and mica. in the specimen here figured, the white layers consist almost exclusively of granular felspar, with here and there a speck of mica and grain of quartz. the dark layers are composed of grey quartz and black mica, with occasionally a grain of felspar intermixed. the rock splits most easily in the plane of these darker layers, and the surface thus exposed is almost entirely covered with shining spangles of mica. the accompanying quartz, however, greatly predominates in quantity, but the most ready cleavage is determined by the abundance of mica in certain parts of the dark layer. instead of these thin laminæ, gneiss is sometimes simply divided into thick beds, in which the mica has only a slight degree of parallelism to the planes of stratification. the term "gneiss," however, in geology is commonly used in a wider sense, to designate a formation in which the above-mentioned rock prevails, but with which any one of the other metamorphic rocks, and more especially hornblende-schist, may alternate. these other members of the metamorphic series are, in this case, considered as subordinate to the true gneiss. the different varieties of rock allied to gneiss, into which felspar enters as an essential ingredient, will be understood by referring to what was said of granite. thus, for example, hornblende may be superadded to mica, quartz, and felspar, forming a syenitic gneiss; or talc may be substituted for mica, constituting talcose gneiss, a rock composed of felspar, quartz, and talc, in distinct crystals or grains (stratified protogine of the french). _hornblende-schist_ is usually black, and composed principally of hornblende, with a variable quantity of felspar, and sometimes grains of quartz. when the hornblende and felspar are nearly in equal quantities, and the rock is not slaty, it corresponds in character with the greenstones of the trap family, and has been called "primitive greenstone." it may be termed hornblende rock. some of these hornblendic masses may really have been volcanic rocks, which have since assumed a more crystalline or metamorphic texture. _mica-schist_, or _micaceous schist_, is, next to gneiss, one of the most abundant rocks of the metamorphic series. it is slaty, essentially composed of mica and quartz, the mica sometimes appearing to constitute the whole mass. beds of pure quartz also occur in this formation. in some districts, garnets in regular twelve-sided crystals form an integrant part of mica-schist. this rock passes by insensible gradations into clay-slate. _clay-slate_, or _argillaceous schist_.--this rock resembles an indurated clay or shale, is for the most part extremely fissile, often affording good roofing slate. it may consist of the ingredients of gneiss, or of an extremely fine mixture of mica and quartz, or talc and quartz. occasionally it derives a shining and silky lustre from the minute particles of mica or talc which it contains. it varies from greenish or bluish-grey to a lead colour. it may be said of this, more than of any other schist, that it is common to the metamorphic and fossiliferous series, for some clay-slates taken from each division would not be distinguishable by mineralogical characters. _quartzite_, or _quartz rock_, is an aggregate of grains of quartz, which are either in minute crystals, or in many cases slightly rounded, occurring in regular strata, associated with gneiss or other metamorphic rocks. compact quartz, like that so frequently found in veins, is also found together with granular quartzite. both of these alternate with gneiss or mica-schist, or pass into those rocks by the addition of mica, or of felspar and mica. _chlorite-schist_ is a green slaty rock, in which chlorite is abundant in foliated plates, usually blended with minute grains of quartz, or sometimes with felspar or mica. often associated with, and graduating into, gneiss and clay-slate. _hypogene_, or _metamorphic limestone_.--this rock, commonly called _primary limestone_, is sometimes a thick bedded white crystalline granular marble used in sculpture; but more frequently it occurs in thin beds, forming a foliated schist much resembling in colour and appearance certain varieties of gneiss and mica-schist. it alternates with both these rocks, and in like manner with argillaceous schist. it then usually contains some crystals of mica, and occasionally quartz, felspar, hornblende, and talc. this member of the metamorphic series enters sparingly into the structure of the hypogene districts of norway, sweden, and scotland, but is largely developed in the alps. before offering any farther observations on the probable origin of the metamorphic rocks, i subjoin, in the form of a glossary, a brief explanation of some of the principal varieties and their synonymies. actinolite-schist. a slaty foliated rock, composed chiefly of actinolite, (an emerald-green mineral, allied to hornblende,) with some admixture of felspar, or quartz, or mica. ampelite. aluminous slate (brongniart); occurs both in the metamorphic and fossiliferous series. amphibolite. hornblende rock, which see. argillaceous-schist, or clay-slate. _see_ p. . arkose. term used by brongniart for granular quartzite, which see. chiastolite-slate scarcely differs from clay-slate, but includes numerous crystals of chiastolite; in considerable thickness in cumberland. chiastolite occurs in long slender rhomboidal crystals. for composition, see table, p. . chlorite-schist. a green slaty rock, in which chlorite, a green scaly mineral, is abundant. _see_ p. . clay-slate, or argillaceous-schist. _see_ p. . eurite and euritic porphyry. a base of compact felspar, with grains of laminar felspar, and often mica and other minerals disseminated (brongniart). m. d'aubuisson regards eurite as an extremely fine-grained granite, in which felspar predominates, the whole forming an apparently homogeneous rock. eurite has been already mentioned as a plutonic rock, but occurs also in beds subordinate to gneiss or mica-slate. gneiss. a stratified or laminated rock, same composition as granite. _see_ p. . hornblende rock, or amphibolite. composed of hornblende and felspar. the same composition as hornblende-schist, stratified, but not fissile. _see_ p. . hornblende-schist, or slate. composed chiefly of hornblende, with occasionally some felspar. _see_ p. . hornblendic or syenitic-gneiss. composed of felspar, quartz, and hornblende. hypogene limestone. _see_ p. . marble. _see_ p. . mica-schist, or micaceous-schist. a slaty rock, composed of mica and quartz in variable proportions. _see_ p. . mica-slate. _see_ mica-schist, p. . phyllade. d'aubuisson's term for clay-slate, from +phullas+, a heap of leaves. primary limestone. _see_ hypogene limestone, p. . protogine. _see_ talcose-gneiss, p. .; when unstratified it is talcose-granite. quartz rock, or quartzite. a stratified rock; an aggregate of grains of quartz. _see_ p. . serpentine occurs in both divisions of the hypogene series, as a stratified or unstratified rock; contains much magnesia; is chiefly composed of the mineral called serpentine, mixed with diallage, talc, and steatite. the pure varieties of this rock, called noble serpentine, consist of a hydrated silicate of magnesia, generally of a greenish colour: this base is commonly mixed with oxide of iron. talcose-gneiss. same composition as talcose-granite or protogine, but either stratified or laminated. _see_ p. . talcose-schist consists chiefly of talc, or of talc and quartz, or of talc and felspar, and has a texture something like that of clay-slate. whitestone. same as eurite. _origin of the metamorphic strata._ having said thus much of the mineral composition of the metamorphic rocks, i may combine what remains to be said of their structure and history with an account of the opinions entertained of their probable origin. at the same time, it may be well to forewarn the reader that we are here entering upon ground of controversy, and soon reach the limits where positive induction ends, and beyond which we can only indulge in speculations. it was once a favourite doctrine, and is still maintained by many, that these rocks owe their crystalline texture, their want of all signs of a mechanical origin, or of fossil contents, to a peculiar and nascent condition of the planet at the period of their formation. the arguments in refutation of this hypothesis will be more fully considered when i show, in the last chapter of this volume, to how many different ages the metamorphic formations are referable, and how gneiss, mica-schist, clay-slate, and hypogene limestone (that of carrara for example), have been formed, not only since the first introduction of organic beings into this planet, but even long after many distinct races of plants and animals had passed away in succession. the doctrine respecting the crystalline strata, implied in the name metamorphic, may properly be treated of in this place; and we must first inquire whether these rocks are really entitled to be called stratified in the strict sense of having been originally deposited as sediment from water. the general adoption by geologists of the term stratified, as applied to these rocks, sufficiently attests their division into beds very analogous, at least in form, to ordinary fossiliferous strata. this resemblance is by no means confined to the existence in both of an occasional slaty structure, but extends to every kind of arrangement which is compatible with the absence of fossils, and of sand, pebbles, ripple-mark, and other characters which the metamorphic theory supposes to have been obliterated by plutonic action. thus, for example, we behold alike in the crystalline and fossiliferous formations an alternation of beds varying greatly in composition, colour, and thickness. we observe, for instance, gneiss alternating with layers of black hornblende-schist, or with granular quartz, or limestone; and the interchange of these different strata may be repeated for an indefinite number of times. in the like manner, mica-schist alternates with chlorite-schist, and with granular limestone in thin layers. as in fossiliferous formations strata of pure siliceous sand alternate with micaceous sand and with layers of clay, so in the crystalline or metamorphic rocks we have beds of pure quartzite alternating with mica-schist and clay-slate. as in the secondary and tertiary series we meet with limestone alternating again and again with micaceous or argillaceous sand, so we find in the hypogene, gneiss and mica-schist alternating with pure and impure granular limestones. it has also been shown that the ripple-mark is very commonly repeated throughout a considerable thickness of fossiliferous strata; so in mica-schist and gneiss, there is sometimes an undulation of the laminæ on a minute scale, which may, perhaps, be a modification of similar inequalities in the original deposit. in the crystalline formations also, as in many of the sedimentary before described, single strata are sometimes made up of laminæ placed diagonally, such laminæ not being regularly parallel to the planes of cleavage. [illustration: fig. . lamination of clay-slate, montagne de seguinat, near gavarnie, in the pyrenees.] this disposition of the layers is illustrated in the accompanying diagram, in which i have represented carefully the stratification of a coarse argillaceous schist, which i examined in the pyrenees, part of which approaches in character to a green and blue roofing slate, while part is extremely quartzose, the whole mass passing downwards into micaceous schist. the vertical section here exhibited is about feet in height, and the layers are sometimes so thin that fifty may be counted in the thickness of an inch. some of them consist of pure quartz. the inference drawn from the phenomena above described in favour of the aqueous origin of clay-slate and other crystalline strata, is greatly strengthened by the fact that many of these metamorphic rocks occasionally alternate with, and sometimes pass by intermediate gradations into, rocks of a decidedly mechanical origin, and exhibiting traces of organic remains. the fossiliferous formations, moreover, into which this passage is effected, are by no means invariably of the same age nor of the highest antiquity, as will be afterwards explained. _stratification of the metamorphic rocks distinct from cleavage._--the beds into which gneiss, mica-schist, and hypogene limestone divide, exhibit most commonly, like ordinary strata, a want of perfect geometrical parallelism. for this reason, therefore, in addition to the alternate recurrence of layers of distinct materials, the stratified arrangement of the crystalline rocks cannot be explained away by supposing it to be simply a divisional structure like that to which we owe some of the slates used for writing and roofing. _slaty cleavage_, as it has been called, has in many cases been produced by the regular deposition of thin plates of fine sediment one upon another; but there are many instances where it is decidedly unconnected with such a mode of origin, and where it is not even confined to the aqueous formations. some kinds of trap, for example, as clinkstone, split into laminæ, and are used for roofing. there are, says professor sedgwick, three distinct forms of structure exhibited in certain rocks throughout large districts: viz.--first, stratification; secondly, joints; and thirdly, slaty cleavage; the two last having no connection with true bedding, and having been superinduced by causes absolutely independent of gravitation. all these different structures must have different names, even though there be some cases where it is impossible, after carefully studying the appearances, to decide upon the class to which they belong.[ -a] _joints._--now, in regard to the second of these forms of structure or joints, they are natural fissures which often traverse rocks in straight and well-determined lines. they afford to the quarryman, as sir r. murchison observes, when speaking of the phenomena, as exhibited in shropshire and the neighbouring counties, the greatest aid in the extraction of blocks of stone; and, if a sufficient number cross each other, the whole mass of rock is split into symmetrical blocks.[ -b] the faces of the joints are for the most part smoother and more regular than the surfaces of true strata. the joints are straight-cut chinks, often slightly open, often passing, not only through layers of successive deposition, but also through balls of limestone or other matter which have been formed by concretionary action, since the original accumulation of the strata. such joints, therefore, must often have resulted from one of the last changes superinduced upon sedimentary deposits.[ -c] in the annexed diagram the flat surfaces of rock a, b, c, represent exposed faces of joints, to which the walls of other joints, j j, are parallel. s s are the lines of stratification; d d are lines of slaty cleavage, which intersect the rock at a considerable angle to the planes of stratification. [illustration: fig. . stratification, joints, and cleavage.] joints, according to professor sedgwick, are distinguishable from lines of slaty cleavage in this, that the rock intervening between two joints has no tendency to cleave in a direction parallel to the planes of the joints, whereas a rock is capable of indefinite subdivision in the direction of its slaty cleavage. in some cases where the strata are curved, the planes of cleavage are still perfectly parallel. this has been observed in the slate rocks of part of wales (see fig. .), which consist of a hard greenish slate. the true bedding is there indicated by a number of parallel stripes, some of a lighter and some of a darker colour than the general mass. such stripes are found to be parallel to the true planes of stratification, wherever these are manifested by ripple-mark, or by beds containing peculiar organic remains. some of the contorted strata are of a coarse mechanical structure, alternating with fine-grained crystalline chloritic slates, in which case the same slaty cleavage extends through the coarser and finer beds, though it is brought out in greater perfection in proportion as the materials of the rock are fine and homogeneous. it is only when these are very coarse that the cleavage planes entirely vanish. these planes are usually inclined at a very considerable angle to the planes of the strata. in the welsh chains, for example, the average angle is as much as from ° to °. sometimes the cleavage planes dip towards the same point of the compass as those of stratification, but more frequently to opposite points. it may be stated as a general rule, that when beds of coarser materials alternate with those composed of finer particles, the slaty cleavage is either entirely confined to the fine-grained rock, or is very imperfectly exhibited in that of coarser texture. this rule holds, whether the cleavage is parallel to the planes of stratification or not. [illustration: fig. . parallel planes of cleavage intersecting curved strata. (sedgwick.)] in the swiss and savoy alps, as mr. bakewell has remarked, enormous masses of limestone are cut through so regularly by nearly vertical partings, and these are often so much more conspicuous than the seams of stratification, that an inexperienced observer will almost inevitably confound them, and suppose the strata to be perpendicular in places where in fact they are almost horizontal.[ -a] now these joints are supposed to be analogous to those partings which have been already observed to separate volcanic and plutonic rocks into cuboidal and prismatic masses. on a small scale we see clay and starch when dry split into similar shapes, which is often caused by simple contraction, whether the shrinking be due to the evaporation of water, or to a change of temperature. it is well known that many sandstones and other rocks expand by the application of moderate degrees of heat, and then contract again on cooling; and there can be no doubt that large portions of the earth's crust have, in the course of past ages, been subjected again and again to very different degrees of heat and cold. these alternations of temperature have probably contributed largely to the production of joints in rocks. in some countries, as in saxony, where masses of basalt rest on sandstone, the aqueous rock has for the distance of several feet from the point of junction assumed a columnar structure similar to that of the trap. in like manner some hearthstones, after exposure to the heat of a furnace without being melted, have become prismatic. certain crystals also acquire by the application of heat a new internal arrangement, so as to break in a new direction, their external form remaining unaltered. sir r. murchison observes, that in referring both joints and slaty cleavage to crystalline action, we are borne out by a well-known analogy in which crystallization has in like manner given rise to two distinct kinds of structure in the same body. thus, for example, in a six-sided prism of quartz, the planes of cleavage are distinct from those of the prism. it is impossible to cleave the crystals parallel to the plane of the prism, just as slaty rocks cannot be cleaved parallel to the joints; but the quartz crystal, like the older schists, may be cleaved _ad infinitum_ in the direction of the cleavage planes.[ -a] it seems, therefore, that the fissures called joints may have been the result of different causes, as of some modification of crystalline action, or simple contraction during consolidation, or during a change of temperature. and there are cases where joints may have been due to mechanical violence, and the strain exerted on strata during their upheaval, or when they have sunk down below their former level. professor phillips has suggested that the previous existence of divisional planes may often have determined, and must greatly have modified, the lines and points of fracture caused in rocks by those forces to which they owe their elevation or dislocations. these lines and points being those of least resistance, cannot fail to have influenced the direction in which the solid mass would give way on the application of external force. professor phillips has also remarked that in some slaty rocks the form of the outline of fossil shells and trilobites has been much changed by distortion, which has taken place in a longitudinal, transverse, or oblique direction. this change, he adds, seems to be the result of a "creeping movement" of the particles of the rock along the planes of cleavage, its direction being always uniform over the same tract of country, and its amount in space being sometimes measurable, and being as much as a quarter or even half an inch. the hard shells are not affected, but only those which are thin.[ -b] mr. d. sharpe, following up the same line of inquiry, came to the conclusion, that the present distorted forms of the shells in certain british slate rocks may be accounted for by supposing that the rocks in which they are imbedded have undergone compression in a direction perpendicular to the planes of cleavage, and a corresponding expansion in the direction of the dip of the cleavage.[ -c] mr. darwin infers from his observations, that in south america the strike of the cleavage planes is very uniform over wide regions, and that it corresponds with the strike of the planes of foliation in the gneiss and mica-schists of the same parts of chili, tierra del fuego, &c. the explanation which he suggests, is based upon a combination of mechanical and crystalline forces. the planes, he says, of cleavage, and even the foliation of mica-schist and gneiss, may be intimately connected with the planes of different tension to which the area was long subjected, _after_ the main fissures or axis of upheavement had been formed, but _before_ the final consolidation of the mass and the total cessation of all molecular movement.[ -a] i have already stated that some extremely fine slates are perfectly parallel to the planes of stratification, as those of the niesen, for example, near the lake of thun, in switzerland, which contain fucoids, and are no doubt due to successive aqueous deposition. even where the slates are oblique to the general planes of the strata, it by no means follows as a matter of course that they have been caused by crystalline action, for they may be the result of that diagonal lamination which i have before described (p. .). in this case, however, there is usually much irregularity, whereas cleavage planes oblique to the true stratification, which are referred to a crystalline action, are often perfectly symmetrical, and observe a strict geometrical parallelism, even when the strata are contorted, as already described (p. .). professor sedgwick, speaking of the planes of slaty cleavage, where they are decidedly distinct from those of sedimentary deposition, declares his opinion that no retreat of parts, no contraction in the dimensions of rocks in passing to a solid state, can account for the phenomenon. it must be referred to crystalline or polar forces acting simultaneously, and somewhat uniformly, in given directions, on large masses having a homogeneous composition. sir john herschel, in allusion to slaty cleavage, has suggested, "that if rocks have been so heated as to allow a commencement of crystallization; that is to say, if they have been heated to a point at which the particles can begin to move amongst themselves, or at least on their own axes, some general law must then determine the position in which these particles will rest on cooling. probably that position will have some relation to the direction in which the heat escapes. now, when all, or a majority of particles of the same nature, have a general tendency to one position, that must of course determine a cleavage plane. thus we see the infinitesimal crystals of fresh precipitated sulphate of barytes, and some other such bodies, arrange themselves alike in the fluid in which they float; so as, when stirred, all to glance with one light, and give the appearance of silky filaments. some sorts of soap, in which insoluble margarates[ -b] exist, exhibit the same phenomenon when mixed with water; and what occurs in our experiments on a minute scale may occur in nature on a great one."[ -c] footnotes: [ -a] geol. trans., d series, vol. iii. p. . [ -b] the silurian system of rocks, as developed in salop, hereford, &c., p. . [ -c] ibid., p. . [ -a] introduction to geology, chap. iv. [ -a] silurian system of rocks, &c., p. . [ -b] report, brit. ass., cork, , p. . [ -c] quart. geol. journ., vol. iii. p. . . [ -a] geol. obs. on s. america, , p. . [ -b] margaric acid is an oleaginous acid, formed from different animal and vegetable fatty substances. a margarate is a compound of this acid with soda, potash, or some other base, and is so named from its pearly lustre. [ -c] letter to the author, dated cape of good hope, feb. . . chapter xxxvi. metamorphic rocks--_continued_. strata near some intrusive masses of granite converted into rocks identical with different members of the metamorphic series--arguments hence derived as to the nature of plutonic action--time may enable this action to pervade denser masses--from what kinds of sedimentary rock each variety of the metamorphic class may be derived--certain objections to the metamorphic theory considered--lamination of trachyte and obsidian due to motion--whether some kinds of gneiss have become schistose by a similar action. it has been seen that geologists have been very generally led to infer, from the phenomena of joints and slaty cleavage, that mountain masses, of which the sedimentary origin is unquestionable, have been acted upon simultaneously by vast crystalline forces. that the structure of fossiliferous strata has often been modified by some general cause since their original deposition, and even subsequently to their consolidation and dislocation, is undeniable. these facts prepare us to believe that still greater changes may have been worked out by a greater intensity, or more prolonged development of the same agency, combined, perhaps, with other causes. now we have seen that, near the immediate contact of granitic veins and volcanic dikes, very extraordinary alterations in rocks have taken place, more especially in the neighbourhood of granite. it will be useful here to add other illustrations, showing that a texture undistinguishable from that which characterizes the more crystalline metamorphic formations, has actually been superinduced in strata once fossiliferous. in the southern extremity of norway there is a large district, on the west side of the fiord of christiania, in which granite or syenite protrudes in mountain masses through fossiliferous strata, and usually sends veins into them at the point of contact. the stratified rocks, replete with shells and zoophytes, consist chiefly of shale, limestone, and some sandstone, and all these are invariably altered near the granite for a distance of from to yards. the aluminous shales are hardened and have become flinty. sometimes they resemble jasper. ribboned jasper is produced by the hardening of alternate layers of green and chocolate-coloured schist, each stripe faithfully representing the original lines of stratification. nearer the granite the schist often contains crystals of hornblende, which are even met with in some places for a distance of several hundred yards from the junction; and this black hornblende is so abundant that eminent geologists, when passing through the country, have confounded it with the ancient hornblende-schist, subordinate to the great gneiss formation of norway. frequently, between the granite and the hornblende slate, above mentioned, grains of mica and crystalline felspar appear in the schist, so that rocks resembling gneiss and mica-schist are produced. fossils can rarely be detected in these schists, and they are more completely effaced in proportion to the more crystalline texture of the beds, and their vicinity to the granite. in some places the siliceous matter of the schist becomes a granular quartz; and when hornblende and mica are added, the altered rock loses its stratification, and passes into a kind of granite. the limestone, which at points remote from the granite is of an earthy texture, blue colour, and often abounds in corals, becomes a white granular marble near the granite, sometimes siliceous, the granular structure extending occasionally upwards of yards from the junction; and the corals being for the most part obliterated, though sometimes preserved, even in the white marble. both the altered limestone and hardened slate contain garnets in many places, also ores of iron, lead, and copper, with some silver. these alterations occur equally, whether the granite invades the strata in a line parallel to the general strike of the fossiliferous beds, or in a line at right angles to their strike, as will be seen by the accompanying ground plan.[ -a] [illustration: fig. . altered zone of fossiliferous slate and limestone near granite. christiania. _the arrows indicate the dip, and the straight lines the strike, of the beds._] the indurated and ribboned schists above mentioned bear a strong resemblance to certain shales of the coal found at russell's hall, near dudley, where coal-mines have been on fire for ages. beds of shale of considerable thickness, lying over the burning coal, have been baked and hardened so as to acquire a flinty fracture, the layers being alternately green and brick-coloured. the granite of cornwall, in like manner, sends forth veins into a coarse argillaceous-schist, provincially termed killas. this killas is converted into hornblende-schist near the contact with the veins. these appearances are well seen at the junction of the granite and killas, in st. michael's mount, a small island nearly feet high, situated in the bay, at a distance of about three miles from penzance. the granite of dartmoor, in devonshire, says sir h. de la beche, has intruded itself into the slate and slaty sandstone called greywacké, twisting and contorting the strata, and sending veins into them. hence some of the slate rocks have become "micaceous; others more indurated, and with the characters of mica-slate and gneiss; while others again appear converted into a hard-zoned rock strongly impregnated with felspar."[ -a] we learn from the investigations of m. dufrénoy, that in the eastern pyrenees there are mountain masses of granite posterior in date to the formations called lias and chalk of that district, and that these fossiliferous rocks are greatly altered in texture, and often charged with iron-ore, in the neighbourhood of the granite. thus in the environs of st. martin, near st. paul de fénouillet, the chalky limestone becomes more crystalline and saccharoid as it approaches the granite, and loses all trace of the fossils which it previously contained in abundance. at some points, also, it becomes dolomitic, and filled with small veins of carbonate of iron, and spots of red iron-ore. at rancié the lias nearest the granite is not only filled with iron-ore, but charged with pyrites, tremolite, garnet, and a new mineral somewhat allied to felspar, called, from the place in the pyrenees where it occurs, "couzeranite." now the alterations above described as superinduced in rocks by volcanic dikes and granite veins, prove incontestably that powers exist in nature capable of transforming fossiliferous into crystalline strata--powers capable of generating in them a new mineral character, similar, nay, often absolutely identical, with that of gneiss, mica-schist, and other stratified members of the hypogene series. the precise nature of these altering causes, which may provisionally be termed plutonic, is in a great degree obscure and doubtful; but their reality is no less clear, and we must suppose the influence of heat to be in some way connected with the transmutation, if, for reasons before explained, we concede the igneous origin of granite. the experiments of gregory watt, in fusing rocks in the laboratory, and allowing them to consolidate by slow cooling, prove distinctly that a rock need not be perfectly melted in order that a re-arrangement of its component particles should take place, and a partial crystallization ensue.[ -b] we may easily suppose, therefore, that all traces of shells and other organic remains may be destroyed; and that new chemical combinations may arise, without the mass being so fused as that the lines of stratification should be wholly obliterated. we must not, however, imagine that heat alone, such as may be applied to a stone in the open air, can constitute all that is comprised in plutonic action. we know that volcanos in eruption not only emit fluid lava, but give off steam and other heated gases, which rush out in enormous volume, for days, weeks, or years continuously, and are even disengaged from lava during its consolidation. when the materials of granite, therefore, came in contact with the fossiliferous stratum in the bowels of the earth under great pressure, the contained gases might be unable to escape; yet when brought into contact with rocks, might pass through their pores with greater facility than water is known to do (p. .). these aëriform fluids, such as sulphuretted hydrogen, muriatic acid, and carbonic acid, issue in many places from rents in rocks, which they have discoloured and corroded, softening some and hardening others. if the rocks are charged with water, they would pass through more readily; for, according to the experiments of henry, water, under an hydrostatic pressure of feet, will absorb three times as much carbonic acid gas as it can under the ordinary pressure of the atmosphere. although this increased power of absorption would be diminished, in consequence of the higher temperature found to exist as we descend in the earth, yet professor bischoff has shown that the heat by no means augments in such a proportion as to counteract the effect of augmented pressure.[ -a] there are other gases, as well as the carbonic acid, which water absorbs, and more rapidly in proportion to the amount of pressure. now even the most compact rocks may be regarded, before they have been exposed to the air and dried, in the light of sponges filled with water; and it is conceivable that heated gases brought into contact with them, at great depths, may be absorbed readily, and transfused through their pores. although the gaseous matter first observed would soon be condensed, and part with its heat, yet the continual arrival of fresh supplies from below might, in the course of ages, cause the temperature of the water, and with it that of the containing rock, to be materially raised. m. fournet, in his description of the metalliferous gneiss near clermont, in auvergne, states that all the minute fissures of the rock are quite saturated with free carbonic acid gas, which rises plentifully from the soil there and in many parts of the surrounding country. the various elements of the gneiss, with the exception of the quartz, are all softened; and new combinations of the acid, with lime, iron, and manganese, are continually in progress.[ -b] another illustration of the power of subterranean gases is afforded by the stufas of st. calogero, situated in the largest of the lipari islands. here, according to the description published by hoffmann, horizontal strata of tuff, extending for miles along the coast, and forming cliffs more than feet high, have been discoloured in various places, and strangely altered by the "all-penetrating vapours." dark clays have become yellow, or often snow-white; or have assumed a chequered or brecciated appearance, being crossed with ferruginous red stripes. in some places the fumaroles have been found by analysis to consist partly of sublimations of oxide of iron; but it also appears that veins of chalcedony and opal, and others of fibrous gypsum, have resulted from these volcanic exhalations.[ -c] the reader may also refer to m. virlet's account of the corrosion of hard, flinty, and jaspideous rocks near corinth, by the prolonged agency of subterranean gases[ -a]; and to dr. daubeny's description of the decomposition of trachytic rocks in the solfatara, near naples, by sulphuretted hydrogen and muriatic acid gases.[ -b] although in all these instances we can only study the phenomena as exhibited at the surface, it is clear that the gaseous fluids must have made their way through the whole thickness of porous or fissured rocks, which intervene between the subterranean reservoirs of gas and the external air. the extent, therefore, of the earth's crust, which the vapours have permeated and are now permeating, may be thousands of fathoms in thickness, and their heating and modifying influence may be spread throughout the whole of this solid mass. we learn from professor bischoff that the steam of a hot spring at aix-la-chapelle, although its temperature is only from ° to ° f., has converted the surface of some blocks of black marble into a doughy mass. he conceives, therefore, that steam in the bowels of the earth having a temperature equal or even greater than the melting point of lava, and having an elasticity of which even papin's digester can give but a faint idea, may convert rocks into liquid matter.[ -c] the above observations are calculated to meet some of the objections which have been urged against the metamorphic theory on the ground of the small power of rocks to conduct heat; for it is well known that rocks, when dry and in the air, differ remarkably from metals in this respect. it has been asked how the changes which extend merely for a few feet from the contact of a dike could have penetrated through mountain masses of crystalline strata several miles in thickness. now it has been stated that the plutonic influence of the syenite of norway has sometimes altered fossiliferous strata for a distance of a quarter of a mile, both in the direction of their dip and of their strike. (see fig. . p. .) this is undoubtedly an extreme case; but is it not far more philosophical to suppose that this influence may, under favourable circumstances, affect denser masses, than to invent an entirely new cause to account for effects merely differing in quantity, and not in kind? the metamorphic theory does not require us to affirm that some contiguous mass of granite has been the altering power; but merely that an action, existing in the interior of the earth at an unknown depth, whether thermal, electrical, or other, analogous to that exerted near intruding masses of granite, has, in the course of vast and indefinite periods, and when rising perhaps from a large heated surface, reduced strata thousands of yards thick to a state of semi-fusion, so that on cooling they have become crystalline, like gneiss. granite may have been another result of the same action in a higher state of intensity, by which a thorough fusion has been produced; and in this manner the passage from granite into gneiss may be explained. some geologists are of opinion, that the alternate layers of mica and quartz, or mica and felspar, or lime and felspar, are so much more distinct, in certain metamorphic rocks, than the ingredients composing alternate layers in many sedimentary deposits, that the similar particles must be supposed to have exerted a molecular attraction for each other, and to have thus congregated together in layers more distinct in mineral composition than before they were crystallized. in considering, then, the various data already enumerated, the forms of stratification in metamorphic rocks, their passage on the one hand into the fossiliferous, and on the other into the plutonic formations, and the conversions which can be ascertained to have occurred in the vicinity of granite, we may conclude that gneiss and mica-schist may be nothing more than altered micaceous and argillaceous sandstones that granular quartz may have been derived from siliceous sandstone, and compact quartz from the same materials. clay-slate may be altered shale, and granular marble may have originated in the form of ordinary limestone, replete with shells and corals, which have since been obliterated; and, lastly, calcareous sands and marls may have been changed into impure crystalline limestones. "hornblende-schist," says dr. macculloch, "may at first have been mere clay; for clay or shale is found altered by trap into lydian stone, a substance differing from hornblende-schist almost solely in compactness and uniformity of texture."[ -a] "in shetland," remarks the same author, "argillaceous-schist (or clay-slate), when in contact with granite, is sometimes converted into hornblende-schist, the schist becoming first siliceous, and ultimately, at the contact, hornblende-schist."[ -b] the anthracite and plumbago associated with hypogene rocks may have been coal; for not only is coal converted into anthracite in the vicinity of some trap dikes, but we have seen that a like change has taken place generally even far from the contact of igneous rocks, in the disturbed region of the appalachians.[ -c] at worcester, in the state of massachusetts, miles due west of boston, a bed of plumbago and impure anthracite occurs, interstratified with mica-schist. it is about feet in thickness, and has been made use of both as fuel, and in the manufacture of lead pencils. at the distance of miles from the plumbago, there occurs, on the borders of rhode island, an impure anthracite in slates, containing impressions of coal-plants of the genera _pecopteris_, _neuropteris_, _calamites_, &c. this anthracite is intermediate in character between that of pennsylvania and the plumbago of worcester, in which last the gaseous or volatile matter (hydrogen, oxygen, and nitrogen) is to the carbon only in the proportion of per cent. after traversing the country in various directions, i came to the conclusion that the carboniferous shales or slates with anthracite and plants, which in rhode island often pass into mica-schist, have at worcester assumed a perfectly crystalline and metamorphic texture; the anthracite having been nearly transmuted into that state of pure carbon which is called plumbago or graphite.[ -a] the total absence of any trace of fossils has inclined many geologists to attribute the origin of crystalline strata to a period antecedent to the existence of organic beings. admitting, they say, the obliteration, in some cases, of fossils by plutonic action, we might still expect that traces of them would oftener occur in certain ancient systems of slate, in which, as in cumberland, some conglomerates occur. but in urging this argument, it seems to have been forgotten that there are stratified formations of enormous thickness, and of various ages, and some of them very modern, all formed after the earth had become the abode of living creatures, which are, nevertheless, in certain districts, entirely destitute of all vestiges of organic bodies. in some, the traces of fossils may have been effaced by water and acids, at many successive periods; and it is clear, that, the older the stratum, the greater is the chance of its being non-fossiliferous, even if it has escaped all metamorphic action. it has been also objected to the metamorphic theory, that the chemical composition of the secondary strata differs essentially from that of the crystalline schists, into which they are supposed to be convertible.[ -b] the "primary" schists, it is said, usually contain a considerable proportion of potash or of soda, which the secondary clays, shales, and slates do not, these last being the result of the decomposition of felspathic rocks, from which the alkaline matter has been abstracted during the process of decomposition. but this reasoning proceeds on insufficient and apparently mistaken data; for a large portion of what is usually called clay, marl, shale, and slate does actually contain a certain, and often a considerable, proportion of alkali; so that it is difficult, in many countries, to obtain clay or shale sufficiently free from alkaline ingredients to allow of their being burnt into bricks or used for pottery. thus the argillaceous shales and slates of the old red sandstone, in forfarshire and other parts of scotland, are so much charged with alkali, derived from triturated felspar, that, instead of hardening when exposed to fire, they sometimes melt into a glass. they contain no lime, but appear to consist of extremely minute grains of the various ingredients of granite, which are distinctly visible in the coarser-grained varieties, and in almost all the interposed sandstones. these laminated clays and shales might certainly, if crystallized, resemble in composition many of the primary strata. there is also potash in fossil vegetable remains, and soda in the salts by which strata are sometimes so largely impregnated, as in patagonia. another objection has been derived from the alternation of highly crystalline strata with others having a less crystalline texture. the heat, it is said, in its ascent from below, must have traversed the less altered schists before it reached a higher and more crystalline bed. in answer to this, it may be observed, that if a number of strata differing greatly in composition from each other be subjected to equal quantities of heat, there is every probability that some will be more fusible than others. some, for example, will contain soda, potash, lime, or some other ingredient capable of acting as a flux; while others may be destitute of the same elements, and so refractory as to be very slightly affected by a degree of heat capable of reducing others to semi-fusion. nor should it be forgotten that, as a general rule, the less crystalline rocks do really occur in the upper, and the more crystalline in the lower part of each metamorphic series. there are geologists, however, of high authority, who admit the metamorphic origin of gneiss and mica-schist even on a grand scale in some mountain-chains, and who nevertheless believe that gneiss has in some instances been an eruptive rock, deriving its lamination from motion when in a fluid or viscous state. mr. scrope, in his description of the ponza islands, ascribes "the zoned structure of the hungarian perlite (a semi-vitreous trachyte) to its having subsided, in obedience to the impulse of its own gravity, down a slightly inclined plane, while possessed of an imperfect fluidity. in the islands of ponza and palmarola, the direction of the zones is more frequently vertical than horizontal, because the mass was impelled from below upwards."[ -a] in like manner, mr. darwin attributes the lamination and fissile structure of volcanic rocks of the trachytic series, including some obsidians in ascension, mexico, and elsewhere, to their having moved when liquid in the direction of the laminæ. the zones consist sometimes of layers of air-cells drawn out and lengthened in the supposed direction of the moving mass. he compares this division into parallel zones, thus caused by the stretching of a pasty mass as it flowed slowly onwards, to the zoned or ribboned structure of ice, which professor james forbes has so ably explained, showing that it is due to the fissuring of a viscous body in motion.[ -b] mr. darwin also imagines the lamination or _foliation_, as he terms it, of gneiss and mica-schist in south america to be the extreme result of that process of which cleavage is the first effect.[ -c] m. elie de beaumont, while he regards the greater part of the gneiss and mica-schist of the alps as sedimentary strata altered by plutonic action, still conceives that some of the alpine gneiss may have been erupted, or, in other words, may be granite drawn out into parallel laminæ in the manner of trachyte as above alluded to.[ -d] opinions such as these, and others which might be cited, prove the difficulty of arriving at clear theoretical views on this subject. i may also add another difficulty. in many extensive regions experienced geologists have been at a loss to decide which of two sets of divisional planes were referable to cleavage and which to stratification; and that, too, where the rocks are of undisputed aqueous origin. after much doubt, they have sometimes discovered that they had at first mistaken the lines of cleavage for those of deposition, because the former were by far the most marked of the two. now if such slaty masses should become highly crystalline, and be converted into gneiss, hornblende-schist, or any other member of the hypogene class, the cleavage planes would be more likely to remain visible than those of stratification. but although the cause last-mentioned may, in some instances, be a "vera causa," as applied to gneiss and mica-schist, i believe it to be an exception to the general rule. nor would it, i conceive, produce that kind of irregular parallelism in the laminæ which belongs to so many of the hypogene rocks of the grampians, pyrenees, and the white mountains of north america, where i have chiefly studied them. but it will be impossible for the reader duly to appreciate the propriety of the term metamorphic, as applied to the strata formerly called primitive, until i have shown, in the next chapter, at how many distinct periods these crystalline strata have been formed. footnotes: [ -a] keilhau, gæa norvegica, pp. - . [ -a] geol. manual, p. . [ -b] phil. trans., . [ -a] poggendorf's annalen, no. xvi., d series, vol. iii. [ -b] see principles, _index_, "carbonated springs," &c. [ -c] hoffmann's liparischen inseln, p. . leipzig, . [ -a] see princ. of geol.; and bulletin de la soc. géol. de france, tom. ii. p. . [ -b] see princ. of geol.; and daubeny's volcanos, p. . [ -c] jam. ed. new phil. journ., no. . p. . [ -a] syst. of geol., vol. i. p. . [ -b] ibid., p. . [ -c] see above, pp. , . [ -a] see lyell, quart. geol. journ., vol. i. p. . [ -b] dr. boase, primary geology, p. . [ -a] geol. trans., d series, vol. ii. p. . [ -b] darwin, volcanic islands, pp. , . [ -c] geol. obs. in s. america, p. . see also above, p. . [ -d] bulletin, vol. iv. p. . chapter xxxvii. on the different ages of the metamorphic rocks. age of each set of metamorphic strata twofold--test of age by fossils and mineral character not available--test by superposition ambiguous--conversion of dense masses of fossiliferous strata into metamorphic rocks--limestone and shale of carrara--metamorphic strata of modern periods in the alps of switzerland and savoy--why the visible crystalline strata are none of them very modern--order of succession in metamorphic rocks--uniformity of mineral character--why the metamorphic strata are less calcareous than the fossiliferous. according to the theory adopted in the last chapter, the age of each set of metamorphic strata is twofold--they have been deposited at one period, they have become crystalline at another. we can rarely hope to define with exactness the date of both these periods, the fossils having been destroyed by plutonic action, and the mineral characters being the same, whatever the age. superposition itself is an ambiguous test, especially when we desire to determine the period of crystallization. suppose, for example, we are convinced that certain metamorphic strata in the alps, which are covered by cretaceous beds, are altered lias; this lias may have assumed its crystalline texture in the cretaceous or in some tertiary period, the eocene for example. if in the latter, it should be called eocene when regarded as a metamorphic rock, although it be liassic when considered in reference to the era of its deposition. according to this view, the superposition of chalk does not prevent the subjacent _metamorphic_ rock from being eocene. if, however, in the progress of science, we should succeed in ascertaining the twofold chronological relations of the metamorphic formations, it might be useful to adopt a twofold terminology. we might call the strata above alluded to liassic-eocene, or liassic-cretaceous strata of the hypogene class; the first term referring to the era of deposition, the second to that of crystallization. when discussing the ages of the plutonic rocks, we have seen that examples occur of various primary, secondary, and tertiary deposits converted into metamorphic strata, near their contact with granite. there can be no doubt in these cases that strata, once composed of mud, sand, and gravel, or of clay, marl, and shelly limestone, have for the distance of several yards, and in some instances several hundred feet, been turned into gneiss, mica-schist, hornblende-schist, chlorite-schist, quartz rock, statuary marble, and the rest. (see the two preceding chapters.) but when the metamorphic action has operated on a grander scale, it tends entirely to destroy all monuments of the date of its development. it may be easy to prove the identity of two different parts of the same stratum; one, where the rock has been in contact with a volcanic or plutonic mass, and has been changed into marble or hornblende-schist, and another not far distant, where the same bed remains unaltered and fossiliferous; but when we have to compare two portions of a mountain chain--the one metamorphic, and the other unaltered--all the labour and skill of the most practised observers are required. i shall mention one or two examples of alteration on a grand scale, in order to explain to the student the kind of reasoning by which we are led to infer that dense masses of fossiliferous strata have been converted into crystalline rocks. _northern apennines--carrara._--the celebrated marble of carrara, used in sculpture, was once regarded as a type of primitive limestone. it abounds in the mountains of massa carrara, or the "apuan alps," as they have been called, the highest peaks of which are nearly feet high. its great antiquity was inferred from its mineral texture, from the absence of fossils, and its passage downwards into talc-schist and garnetiferous mica-schist; these rocks again graduating downwards into gneiss, which is penetrated, at forno, by granite veins. now the researches of mm. savi, boué, pareto, guidoni, de la beche, hoffmann, and pilla, have demonstrated that this marble, once supposed to be formed before the existence of organic beings, is, in fact, an altered limestone of the oolitic period, and the underlying crystalline schists are secondary sandstones and shales, modified by plutonic action. in order to establish these conclusions it was first pointed out, that the calcareous rocks bordering the gulf of spezia, and abounding in oolitic fossils, assume a texture like that of carrara marble, in proportion as they are more and more invaded by certain trappean and plutonic rocks, such as diorite, euphotide, serpentine, and granite, occurring in the same country. it was then observed that, in places where the secondary formations are unaltered, the uppermost consist of common apennine limestone with nodules of flint, below which are shales, and at the base of all, argillaceous and siliceous sandstones. in the limestone, fossils are frequent, but very rare in the underlying shale and sandstone. then a gradation was traced laterally from these rocks into another and corresponding series, which is completely metamorphic; for at the top of this we find a white granular marble, wholly devoid of fossils, and almost without stratification, in which there are no nodules of flint, but in its place siliceous matter disseminated through the mass in the form of prisms of quartz. below this, and in place of the shales, are talc-schists, jasper, and hornstone; and at the bottom, instead of the siliceous and argillaceous sandstones, are quartzite and gneiss.[ -a] had these secondary strata of the apennines undergone universally as great an amount of transmutation, it would have been impossible to form a conjecture respecting their true age; and then, according to the common method of geological classification, they would have ranked as primary rocks. in that case the date of their origin would have been thrown back to an era antecedent to the deposition of the lower silurian or cambrian strata, although in reality they were formed in the oolitic period, and altered at some subsequent and perhaps much later epoch. _alps of switzerland._--in the alps, analogous conclusions have been drawn respecting the alteration of strata on a still more extended scale. in the eastern part of that chain, some of the primary fossiliferous strata, as well as the older secondary formations, together with the oolitic and cretaceous rocks, are distinctly recognizable. tertiary deposits also appear in a less elevated position on the flanks of the eastern alps; but in the central or swiss alps, the primary fossiliferous and older secondary formations disappear, and the cretaceous, oolitic, liassic, and at some points even the eocene strata, graduate insensibly into metamorphic rocks, consisting of granular limestone, talc-schist, talcose-gneiss, micaceous schist, and other varieties. in regard to the age of this vast assemblage of crystalline strata, we can merely affirm that some of the upper portions are altered newer secondary, and some of them even eocene deposits; but we cannot avoid suspecting that the disappearance both of the older secondary and primary fossiliferous rocks may be owing to their having been all converted in this region into crystalline schist. it is difficult to convey to those who have never visited the alps a just idea of the various proofs which concur to produce this conviction. in the first place, there are certain regions where oolitic, cretaceous, and eocene strata have been turned into granular marble, gneiss, and other metamorphic schists, near their contact with granite. this fact shows undeniably that plutonic causes continued to be in operation in the alps down to a late period, even after the deposition of some of the nummulitic or older eocene formations. having established this point, we are the more willing to believe that many inferior fossiliferous rocks, probably exposed for longer periods to a similar action, may have become metamorphic to a still greater extent. we also discover in parts of the swiss alps dense masses of secondary and even tertiary strata, which have assumed that semi-crystalline texture which werner called transition, and which naturally led his followers, who attached great importance to mineral characters taken alone, to class them as transition formations, or as groups older than the lowest secondary rocks. (see p. .) now, it is probable that these strata have been affected, although in a less intense degree, by that same plutonic action which has entirely altered and rendered metamorphic so many of the subjacent formations; for in the alps, this action has by no means been confined to the immediate vicinity of granite. granite, indeed, and other plutonic rocks, rarely make their appearance at the surface, notwithstanding the deep ravines which lay open to view the internal structure of these mountains. that they exist below at no great depth we cannot doubt, and we have already seen (p. .) that at some points, as in the valorsine, near mont blanc, granite and granitic veins are observable, piercing through talcose gneiss, which passes insensibly upwards into secondary strata. it is certainly in the alps of switzerland and savoy, more than in any other district in europe, that the geologist is prepared to meet with the signs of an intense development of plutonic action; for here we find the most stupendous monuments of mechanical violence, by which strata thousands of feet thick have been bent, folded, and overturned. (see p. .) it is here that marine secondary formations of a comparatively modern date, such as the oolitic and cretaceous, have been upheaved to the height of , , and some eocene strata to elevations of , feet above the level of the sea; and even deposits of the miocene era have been raised or feet, so as to rival in height the loftiest mountains in great britain. if the reader will consult the works of many eminent geologists who have explored the alps, especially those of mm. de beaumont, studer, necker, boué, and murchison, he will learn that they all share, more or less fully, in the opinions above expressed. it has, indeed, been stated by mm. studer and hugi, that there are complete alternations on a large scale of secondary strata, containing fossils, with gneiss and other rocks, of a perfectly metamorphic structure. i have visited some of the most remarkable localities referred to by these authors; but although agreeing with them that there are passages from the fossiliferous to the metamorphic series far from the contact of granite or other plutonic rocks, i was unable to convince myself that the distinct alternations of highly crystalline, with unaltered strata above alluded to, might not admit of a different explanation. in one of the sections described by m. studer in the highest of the bernese alps, namely in the roththal, a valley bordering the line of perpetual snow on the northern side of the jungfrau, there occurs a mass of gneiss feet thick, and , feet long, which i examined, not only resting upon, but also again covered by strata containing oolitic fossils. these anomalous appearances may partly be explained by supposing great solid wedges of intrusive gneiss to have been forced in laterally between strata to which i found them to be in many sections unconformable. the superposition, also, of the gneiss to the oolite may, in some cases, be due to a reversal of the original position of the beds in a region where the convulsions have been on so stupendous a scale. on the sattel also, at the base of the gestellihorn, above enzen, in the valley of urbach, near meyringen, some of the intercalations of gneiss between fossiliferous strata may, i conceive, be ascribed to mechanical derangement. almost any hypothesis of repeated changes of position may be resorted to in a region of such extraordinary confusion. the secondary strata may first have been vertical, and then certain portions may have become metamorphic (the plutonic influence ascending from below), while intervening strata remained unchanged. the whole series of beds may then again have been thrown into a nearly horizontal position, giving rise to the superposition of crystalline upon fossiliferous formations. it was remarked, in chap. xxxiv., that as the hypogene rocks, both stratified and unstratified, crystallize originally at a certain depth beneath the surface, they must always, before they are upraised and exposed at the surface, be of considerable antiquity, relatively to a large portion of the fossiliferous and volcanic rocks. they may be forming at all periods; but before any of them can become visible, they must be raised above the level of the sea, and some of the rocks which previously concealed them must have been removed by denudation. _order of succession in metamorphic rocks._--there is no universal and invariable order of superposition in metamorphic rocks, although a particular arrangement may prevail throughout countries of great extent, for the same reason that it is traceable in those sedimentary formations from which crystalline strata are derived. thus, for example, we have seen that in the apennines, near carrara, the descending series, where it is metamorphic, consists of, st, saccharine marble; dly, talcose-schist; and dly, of quartz-rock and gneiss; where unaltered, of, st, fossiliferous limestone; dly, shale; and dly, sandstone. but if we investigate different mountain chains, we find gneiss, mica-schist, hornblende-schist, chlorite-schist, hypogene, limestone, and other rocks, succeeding each other, and alternating with each other, in every possible order. it is, indeed, more common to meet with some variety of clay-slate forming the uppermost member of a metamorphic series than any other rock; but this fact by no means implies, as some have imagined, that all clay-slates were formed at the close of an imaginary period, when the deposition of the crystalline strata gave way to that of ordinary sedimentary deposits. such clay-slates, in fact, are variable in composition, and sometimes alternate with fossiliferous strata, so that they may be said to belong almost equally to the sedimentary and metamorphic order of rocks. it is probable that had they been subjected to more intense plutonic action, they would have been transformed into hornblende-schist, foliated chlorite-schist, scaly talcose-schist, mica-schist, or other more perfectly crystalline rocks, such as are usually associated with gneiss. _uniformity of mineral character in hypogene rocks._--humboldt has emphatically remarked, that when we pass to another hemisphere, we see new forms of animals and plants, and even new constellations in the heavens; but in the rocks we still recognize our old acquaintances,--the same granite, the same gneiss, the same micaceous schist, quartz-rock, and the rest. it is certainly true that there is a great and striking general resemblance in the principal kinds of hypogene rocks, although of very different ages and countries; but it has been shown that each of these are, in fact, geological families of rocks, and not definite mineral compounds. they are much more uniform in aspect than sedimentary strata, because these last are often composed of fragments varying greatly in form, size, and colour, and contain fossils of different shapes and mineral composition, and acquire a variety of tints from the mixture of various kinds of sediment. the materials of such strata, if melted and made to crystallize, would be subject to chemical laws, simple and uniform in their action, the same in every climate, and wholly undisturbed by mechanical and organic causes. nevertheless, it would be a great error to assume that the hypogene rocks, considered as aggregates of simple minerals, are really more homogeneous in their composition than the several members of the sedimentary series. in the first place, different assemblages of hypogene rocks occur in different countries; and, secondly, in any one district, the rocks which pass under the same name are often extremely variable in their component ingredients, or at least in the proportions in which each of these are present. thus, for example, gneiss and mica-schist, so abundant in the grampians, are wanting in cumberland, wales, and cornwall; in parts of the swiss and italian alps, the gneiss and granite are talcose, and not micaceous, as in scotland; hornblende prevails in the granite of scotland--schorl in that of cornwall--albite in the plutonic rocks of the andes--common felspar in those of europe. in one part of scotland, the mica-schist is full of garnets; in another it is wholly devoid of them: while in south america, according to mr. darwin, it is the gneiss, and not the mica-schist, which is most commonly garnetiferous. and not only do the proportional quantities of felspar, quartz, mica, hornblende, and other minerals, vary in hypogene rocks bearing the same name; but what is still more important, the ingredients, as we have seen, of the same simple mineral are not always constant (p. ., and table, p. .). _the metamorphic strata, why less calcareous than the fossiliferous._--it has been remarked, that the quantity of calcareous matter in metamorphic strata, or, indeed, in the hypogene formations generally, is far less than in fossiliferous deposits. thus the crystalline schists of the grampians in scotland, consisting of gneiss, mica-schist, hornblende-schist, and other rocks, many thousands of yards in thickness, contain an exceedingly small proportion of interstratified calcareous beds, although these have been the objects of careful search for economical purposes. yet limestone is not wanting in the grampians, and it is associated sometimes with gneiss, sometimes with mica-schist, and in other places with other members of the metamorphic series. but where limestone occurs abundantly, as at carrara, and in parts of the alps, in connection with hypogene rocks, it usually forms one of the superior members of the crystalline group. the scarcity, then, of carbonate of lime in the plutonic and metamorphic rocks generally, seems to be the result of some general cause. so long as the hypogene rocks were believed to have originated antecedently to the creation of organic beings, it was easy to impute the absence of lime to the non-existence of those mollusca and zoophytes by which shells and corals are secreted; but when we ascribe the crystalline formations to plutonic action, it is natural to inquire whether this action itself may not tend to expel carbonic acid and lime from the materials which it reduces to fusion or semi-fusion. although we cannot descend into the subterranean regions where volcanic heat is developed, we can observe in regions of spent volcanos, such as auvergne and tuscany, hundreds of springs, both cold and thermal, flowing out from granite and other rocks, and having their waters plentifully charged with carbonate of lime. the quantity of calcareous matter which these springs transfer, in the course of ages, from the lower parts of the earth's crust to the superior or newly formed parts of the same, must be considerable.[ -a] if the quantity of siliceous and aluminous ingredients brought up by such springs were great, instead of being utterly insignificant, it might be contended that the mineral matter thus expelled implies simply the decomposition of ordinary subterranean rocks; but the prodigious excess of carbonate of lime over every other element must, in the course of time, cause the crust of the earth below to be almost entirely deprived of its calcareous constituents, while we know that the same action imparts to newer deposits, ever forming in seas and lakes, an excess of carbonate of lime. calcareous matter is poured into these lakes, and the ocean, by a thousand springs and rivers; so that part of almost every new calcareous rock chemically precipitated, and of many reefs of shelly and coralline stone, must be derived from mineral matter subtracted by plutonic agency, and driven up by gas and steam from fused and heated rocks in the bowels of the earth. not only carbonate of lime, but also free carbonic acid gas is given off plentifully from the soil and crevices of rocks in regions of active and spent volcanos, as near naples, and in auvergne. by this process, fossil shells or corals may often lose their carbonic acid, and the residual lime may enter into the composition of augite, hornblende, garnet, and other hypogene minerals. that the removal of the calcareous matter of fossil shells is of frequent occurrence, is proved by the fact of such organic remains being often replaced by silex or other minerals, and sometimes by the space once occupied by the fossil being left empty, or only marked by a faint impression. we ought not indeed to marvel at the general absence of organic remains from the crystalline strata, when we bear in mind how often fossils are obliterated, wholly or in part, even in tertiary formations--how often vast masses of sandstone and shale, of different ages, and thousands of feet thick, are devoid of fossils--how certain strata may first have been deprived of a portion of their fossils when they became semi-crystalline, or assumed the _transition_ state of werner--and how the remaining organic remains have been effaced when they were rendered metamorphic. some rocks of the last-mentioned class, moreover, must have been exposed again and again to renewed plutonic action. footnotes: [ -a] see notices of savi, hoffmann, and others, referred to by boué, bull. de la soc. géol. de france, tom. v. p. .; and tom. iii. p. xliv.; also pilla, cited by murchison, quart. geol. journ., vol. v. p. . [ -a] see principles, _index_, "calcareous springs." chapter xxxviii. mineral veins. werner's doctrine that mineral veins were fissures filled from above--veins of segregation--ordinary metalliferous veins or lodes--their frequent coincidence with faults--proofs that they originated in fissures in solid rock--veins shifting other veins--polishing of their walls--shells and pebbles in lodes--evidence of the successive enlargement and re-opening of veins--fournet's observations in auvergne--dimensions of veins--why some alternately swell out and contract--filling of lodes by sublimation from below--chemical and electrical action--relative age of the precious metals--copper and lead veins in ireland older than cornish tin--lead vein in lias, glamorganshire--gold in russia--connection of hot springs and mineral veins--concluding remarks. the manner in which metallic substances are distributed through the earth's crust, and more especially the phenomena of those nearly vertical and tabular masses of ore called mineral veins, from which the larger part of the precious metals used by man are obtained,--these are subjects of the highest practical importance to the miner, and of no less theoretical interest to the geologist. the views entertained respecting metalliferous veins have been modified, or, rather, have undergone an almost complete revolution, since the middle of the last century, when werner, as director of the school of mines, at freiberg in saxony, first attempted to generalize the facts then known. he taught that mineral veins had originally been open fissures which were gradually filled up with crystalline and metallic matter, and that many of them, after being once filled, had been again enlarged or re-opened. he also pointed out that veins thus formed are not all referable to one era, but are of various geological dates. such opinions, although slightly hinted at by earlier writers, had never before been generally received, and their announcement by one of high authority and great experience constituted an era in the science. nevertheless, i have shown, when tracing, in another work, the history and progress of geology, that werner was far behind some of his predecessors in his theory of the volcanic rocks, and less enlightened than his contemporary, dr. hutton, in his speculations as to the origin of granite.[ -a] according to him, the plutonic formations, as well as the crystalline schists, were substances precipitated from a chaotic fluid in some primeval or nascent condition of the planet; and the metals, therefore, being closely connected with them, had partaken, according to him, of a like mysterious origin. he also held that the trap rocks were aqueous deposits, and that dikes of porphyry, greenstone, and basalt, were fissures filled with their several contents from above. hence he naturally inferred that mineral veins had derived their component materials from an incumbent ocean, rather than from a subterranean source; that these materials had been first dissolved in the waters above, instead of having risen up by sublimation from lakes and seas of igneous matter below. in proportion as the hypothesis of a primeval fluid, or "chaotic menstruum," was abandoned, in reference to the plutonic formations, and when all geologists had come to be of one mind as to the true relation of the volcanic and trappean rocks, reasonable hopes began to be entertained that the phenomena of mineral veins might be explained by known causes, or by chemical, thermal, and electrical agency still at work in the interior of the earth. the grounds of this conclusion will be better understood when the geological facts brought to light by mining operations have been described and explained. _on different kinds of mineral veins._--every geologist is familiarly acquainted with those veins of quartz which abound in hypogene strata, forming lenticular masses of limited extent. they are sometimes observed, also, in sandstones and shales. veins of carbonate of lime are equally common in fossiliferous rocks, especially in limestones. such veins appear to have once been chinks or small cavities, caused, like cracks in clay, by the shrinking of the mass, which has consolidated from a fluid state, or has simply contracted its dimensions in passing from a higher to a lower temperature. siliceous, calcareous, and occasionally metallic matters, have sometimes found their way simultaneously into such empty spaces, by infiltration from the surrounding rocks, or by segregation, as it is often termed. mixed with hot water and steam, metallic ores may have permeated a pasty matrix until they reached those receptacles formed by shrinkage, and thus gave rise to that irregular assemblage of veins, called by the germans a "stockwerk," in allusion to the different floors on which the mining operations are in such cases carried on. the more ordinary or regular veins are usually worked in vertical shafts, and have evidently been fissures produced by mechanical violence. they traverse all kinds of rocks, both hypogene and fossiliferous, and extend downwards to indefinite or unknown depths. we may assume that they correspond with such rents as we see caused from time to time by the shock of an earthquake. metalliferous veins, referable to such agency, are occasionally a few inches wide, but more commonly or feet. they hold their course continuously in a certain prevailing direction for miles or leagues, passing through rocks varying in mineral composition. [ illustrations: fig. . fig. . fig. . vertical sections of the mine of huel peever, redruth, cornwall.] _that metalliferous veins were fissures._--as some intelligent miners, after an attentive study of metalliferous veins, have been unable to reconcile many of their characteristics with the hypothesis of fissures, i shall begin by stating the evidence in its favour. the most striking fact perhaps which can be adduced in its support is, the coincidence of a considerable proportion of mineral veins with _faults_, or those dislocations of rocks which are indisputably due to mechanical force, as above explained (p. .). there are even proofs in almost every mining district of a succession of faults, by which the opposite walls of rents, now the receptacles of metallic substances, have suffered displacement. thus, for example, suppose _a a_, fig. ., to be a tin lode in cornwall, the term _lode_ being applied to veins containing metallic ores. this lode, running east and west, is a yard wide, and is shifted by a copper lode (_b b_), of similar width. the first fissure (_a a_) has been filled with various materials, partly of chemical origin, such as quartz, fluor-spar, peroxide of tin, sulphuret of copper, arsenical pyrites, bismuth, and sulphuret of nickel, and partly of mechanical origin, comprising clay and angular fragments or detritus of the intersected rocks. the plates of quartz and the ores are, in some places, parallel to the vertical sides or walls of the vein, being divided from each other by alternating layers of clay, or other earthy matter. occasionally the metallic ores are disseminated in detached masses among the veinstones. it is clear that, after the gradual introduction of the tin and other substances, the second rent (_b b_) was produced by another fracture accompanied by a displacement of the rocks along the plane of _b b_. this new opening was then filled with minerals, some of them resembling those in _a a_, as fluor-spar (or fluate of lime) and quartz; others different, the copper being plentiful and the tin wanting or very scarce. we must next suppose the shock of a third earthquake to occur, breaking asunder all the rocks along the line c _c_, fig. .; the fissure in this instance, being only inches wide, and simply filled with clay, derived, probably, from the friction of the walls of the rent, or partly, perhaps, washed in from above. this new movement has heaved the rock in such a manner as to interrupt the continuity of the copper vein (_b b_), and, at the same time, to shift or heave laterally in the same direction a portion of the tin vein which had not previously been broken. again, in fig. . we see evidence of a fourth fissure (_d d_), also filled with clay, which has cut through the tin vein (_a a_), and has lifted it slightly upwards towards the south. the various changes here represented are not ideal, but are exhibited in a section obtained in working an old cornish mine, long since abandoned, in the parish of redruth, called huel peever, and described both by mr. williams and mr. carne.[ -a] the principal movement here referred to, or that of _c c_, fig. ., extends through a space of no less than feet; but in this, as in the case of the other three, it will be seen that the outline of the country above, or the geographical features of cornwall, are not affected by any of the dislocations, a powerful denuding force having clearly been exerted subsequently to all the faults. (see above, p. .) it is commonly said in cornwall, that there are eight distinct systems of veins which can in like manner be referred to as many successive movements or fractures; and the german miners of the hartz mountains speak also of eight systems of veins, referable to as many periods. besides the proofs of mechanical action already explained, the opposite walls of veins are frequently polished and striated, as if they had undergone great friction, and this even in cases where there has been no shift. we may attribute such rubbing to a vibratory motion known to accompany earthquakes, and to produce trituration on the opposite walls of rents. similar movements have sometimes occurred in mineral veins which had been wholly or partially filled up; for included pieces of rock, detached from the sides, are found to be rounded, polished, and striated. that a great many veins communicated originally with the surface of the country above, or with the bed of the sea, is proved by the occurrence in them of well rounded pebbles, agreeing with those in superficial alluviums, as in auvergne and saxony. in bohemia, such pebbles have been met with at the depth of fathoms. in cornwall, mr. carne mentions true pebbles of quartz and slate in a tin lode of the relistran mine, at the depth of feet below the surface. they were cemented by oxide of tin and bisulphuret of copper, and were traced over a space more than feet long and as many wide.[ -a] marine fossil shells, also, have been found at great depths, having probably been engulphed during submarine earthquakes. thus, a gryphæa is stated by m. virlet to have been met with in a lead-mine near sémur, in france, and a madrepore in a compact vein of cinnabar in hungary.[ -b] when different sets or systems of veins occur in the same country, those which are supposed to be of contemporaneous origin, and which are filled with the same kind of metals, often maintain a general parallelism of direction. thus, for example, both the tin and copper veins in cornwall run nearly east and west, while the lead-veins run north and south; but there is no general law of direction common to different mining districts. the parallelism of the veins is another reason for regarding them as ordinary fissures, for we observe that contemporaneous trap dikes, admitted by all to be masses of melted matter which have filled rents, are often parallel. assuming, then, that veins are simply fissures in which chemical and mechanical deposits have accumulated, we may next consider the proofs of their having been filled gradually and often during successive enlargements. i have already spoken of parallel layers of clay, quartz, and ore. werner himself observed, in a vein near gersdorff, in saxony, no less than thirteen beds of different minerals, arranged with the utmost regularity on each side of the central layer. this layer was formed of two beds of calcareous spar, which had evidently lined the opposite walls of a vertical cavity. the thirteen beds followed each other in corresponding order, consisting of fluor-spar, heavy spar, galena, &c. in these cases, the central mass has been last formed, and the two plates which coat the outer walls of the rent on each side are the oldest of all. if they consist of crystalline precipitates, they may be explained by supposing the fissure to have remained unaltered in its dimensions, while a series of changes occurred in the nature of the solutions which rose up from below; but such a mode of deposition, in the case of many successive and parallel layers, appears to be exceptional. if a veinstone consist of crystalline matter, the points of the crystals are always turned inwards, or towards the centre of the vein; in other words, they point in that direction where there was most space for the development of the crystals. thus each new layer receives the impression of the crystals of the preceding layer, and imprints its crystals on the one which follows, until at length the whole of the vein is filled: the two layers which meet dovetail the points of their crystals the one into the other. but in cornwall, some lodes occur where the vertical plates, or _combs_, as they are there called, exhibit crystals so dovetailed as to prove that the same fissure has been often enlarged. sir h. de la beche gives the following curious and instructive example (fig. .) from a copper-mine in granite, near redruth.[ -a] each of the plates or combs (_a_, _b_, _c_, _d_, _e_, _f_) are double, having the points of their crystals turned inwards along the axis of the comb. the sides or walls ( , , , , and ) are parted by a thin covering of ochreous clay, so that each comb is readily separable from another by a moderate blow of the hammer. the breadth of each represents the whole width of the fissure at six successive periods, and the outer walls of the vein, where the first narrow rent was formed, consisted of the granitic surfaces and . [illustration: fig. . copper lode, near redruth, enlarged at six successive periods.] a somewhat analogous interpretation is applicable to numbers of other cases, where clay, sand, or angular detritus, alternate with ores and veinstones. thus, we may imagine the sides of a fissure to be encrusted with siliceous matter, as von buch observed, in lancerote, the walls of a volcanic crater formed in to be traversed by an open rent in which hot vapours had deposited hydrate of silica, the incrustation nearly extending to the middle.[ -b] such a vein may then be filled with clay or sand, and afterwards re-opened, the new rent dividing the argillaceous deposit, and allowing a quantity of rubbish to fall down. various metals and spars may then be precipitated from aqueous solutions among the interstices of this heterogeneous mass. that such changes have repeatedly occurred, is demonstrated by occasional cross-veins, implying the oblique fracture of previously formed chemical and mechanical deposits. thus, for example, m. fournet, in his description of some mines in auvergne worked under his superintendence, observes, that the granite of that country was first penetrated by veins of granite, and then dislocated, so that open rents crossed both the granite and the granitic veins. into such openings, quartz, accompanied by sulphurets of iron and arsenical pyrites, was introduced. another convulsion then burst open the rocks along the old line of fracture, and the first set of deposits were cracked and often shattered, so that the new rent was filled, not only with angular fragments of the adjoining rocks, but with pieces of the older veinstones. polished and striated surfaces on the sides or in the contents of the vein also attest the reality of these movements. a new period of repose then ensued, during which various sulphurets were introduced, together with hornstone quartz, by which angular fragments of the older quartz before mentioned were cemented into a breccia. this period was followed by other dilatations of the same veins, and other sets of mineral deposits, until, at last, pebbles of the basaltic lavas of auvergne, derived from superficial alluviums, probably of miocene or older pliocene date, were swept into the veins. i have not space to enumerate all the changes minutely detailed by m. fournet, but they are valuable, both to the miner and geologist, as showing how the supposed signs of violent catastrophes may be the monuments, not of one paroxysmal shock, but of reiterated movements. such repeated enlargement and re-opening of veins might have been anticipated, if we adopt the theory of fissures, and reflect how few of them have ever been sealed up entirely, and that a country with fissures only partially filled must naturally offer much feebler resistance along the old lines of fracture than any where else. it is quite otherwise in the case of dikes, where each opening has been the receptacle of one continuous and homogeneous mass of melted matter, the consolidation of which has taken place under considerable pressure. trappean dikes can rarely fail to strengthen the rocks at the points where before they were weakest; and if the upheaving force is again exerted in the same direction, the crust of the earth will give way anywhere rather than at the precise points where the first rents were produced. a large proportion of metalliferous veins have their opposite walls nearly parallel, and sometimes over a wide extent of country. there is a fine example of this in the celebrated vein of andreasberg in the hartz, which has been worked for a depth of yards perpendicularly, and horizontally, retaining almost every where a width of feet. but many lodes in cornwall and elsewhere are extremely variable in size, being or inches in one part, and then or feet in another, at the distance of a few fathoms, and then again narrowing as before. such alternate swelling and contraction is so often characteristic as to require explanation. the walls of fissures in general, observes sir h. de la beche, are rarely perfect planes throughout their entire course, nor could we well expect them to be so, since they commonly pass through rocks of unequal hardness and different mineral composition. if, therefore, the opposite sides of such irregular fissures slide upon each other, that is to say, if there be a fault, as in the case of so many mineral veins, the parallelism of the opposite walls is at once entirely destroyed, as will be readily seen by studying the annexed diagrams. [illustration: fig. . schematic sketch.] [illustration: fig. . schematic sketch.] [illustration: fig. . schematic sketch.] let _a b_, fig. ., be a line of fracture traversing a rock, and let _a b_, fig. ., represent the same line. now, if we cut a piece of paper representing this line, and then move the lower portion of this cut paper sideways from _a_ to _a'_, taking care that the two pieces of paper still touch each other at the points , , , , , we obtain an irregular aperture at _c_, and isolated cavities at _d d d_, and when we compare such figures with nature we find that, with certain modifications, they represent the interior of faults and mineral veins. if, instead of sliding the cut paper to the right hand, we move the lower part towards the left, about the same distance that it was previously slid to the right, we obtain considerable variation in the cavities so produced, two long irregular open spaces, _f f_, fig. ., being then formed. this will serve to show to what slight circumstances considerable variations in the character of the openings between unevenly fractured surfaces may be due, such surfaces being moved upon each other, so as to have numerous points of contact. [illustration: fig. . schematic sketch.] most lodes are perpendicular to the horizon, or nearly so; but some of them have a considerable inclination or "hade," as it is termed, the angles of dip varying from ° to °. the course of a vein is frequently very straight; but if tortuous, it is found to be choked up with clay, stones, and pebbles, at points where it departs most widely from verticality. hence at places, such as _a_, fig. ., the miner complains that the ores are "nipped," or greatly reduced in quantity, the space for their free deposition having been interfered with in consequence of the pre-occupancy of the lode by earthy materials. when lodes are many fathoms wide, they are usually filled for the most part with earthy matter, and fragments of rock, through which the ores are much disseminated. the metallic substances frequently coat or encircle detached pieces of rock, which our miners call "horses" or "riders." that we should find some mineral veins which split into branches is also natural, for we observe the same in regard to open fissures. _chemical deposits in veins._--if we now turn from the mechanical to the chemical agencies which have been instrumental in the production of mineral veins, it may be remarked that those parts of fissures which were not choked up with the ruins of fractured rocks must always have been filled with water; and almost every vein has probably been the channel by which hot springs, so common in countries of volcanos and earthquakes, have made their way to the surface. for we know that the rents in which ores abound extend downwards to vast depths, where the temperature of the interior of the earth is more elevated. we also know that mineral veins are most metalliferous near the contact of plutonic and stratified formations, especially where the former send veins into the latter, a circumstance which indicates an original proximity of veins at their inferior extremity to igneous and heated rocks. it is moreover acknowledged that even those mineral and thermal springs which, in the present state of the globe, are far from volcanos, are nevertheless observed to burst out along great lines of upheaval and dislocation of rocks.[ -a] it is also ascertained that all the substances with which hot springs are impregnated agree with those discharged in a gaseous form from volcanos. many of these bodies occur as veinstones; such as silex, carbonate of lime, sulphur, fluor-spar, sulphate of barytes, magnesia, oxide of iron, and others. i may add that, if veins have been filled with gaseous emanations from masses of melted matter, slowly cooling in the subterranean regions, the contraction of such masses as they pass from a plastic to a solid state would, according to the experiments of deville on granite (a rock which may be taken as a standard), produce a reduction in volume amounting to per cent. the slow crystallization, therefore, of such plutonic rocks supplies us with a force not only capable of rending open the incumbent rocks by causing a failure of support, but also of giving rise to faults whenever one portion of the earth's crust subsides slowly while another contiguous to it happens to rest on a different foundation, so as to remain unmoved. although we are led to infer, from the foregoing reasoning, that there has often been an intimate connection between metalliferous veins and hot springs holding mineral matter in solution, yet we must not on that account expect that the contents of hot springs and mineral veins would be identical. on the contrary, m. e. de beaumont has judiciously observed that we ought to find in veins those substances which, being least soluble, are not discharged by hot springs,--or that class of simple and compound bodies which the thermal waters ascending from below would first precipitate on the walls of a fissure, as soon as their temperature began slightly to diminish. the higher they mount towards the surface, the more will they cool, till they acquire the average temperature of springs, being in that case chiefly charged with the most soluble substances, such as the alkalis, soda and potash. these are not met with in veins, although they enter so largely into the composition of granitic rocks.[ -b] to a certain extent, therefore, the arrangement and distribution of metallic matter in veins may be referred to ordinary chemical action, or to those variations in temperature, which waters holding the ores in solution must undergo, as they rise upwards from great depths in the earth. but there are other phenomena which do not admit of the same simple explanation. thus, for example, in derbyshire, veins containing ores of lead, zinc, and copper, but chiefly lead, traverse alternate beds of limestone and greenstone. the ore is plentiful where the walls of the rent consist of limestone, but is reduced to a mere string when they are formed of greenstone, or "toadstone," as it is called provincially. not that the original fissure is narrower where the greenstone occurs, but because more of the space is there filled with veinstones, and the waters at such points have not parted so freely with their metallic contents. "lodes in cornwall," says mr. robert w. fox, "are very much influenced in their metallic riches by the nature of the rock which they traverse, and they often change in this respect very suddenly, in passing from one rock to another. thus many lodes which yield abundance of ore in granite, are unproductive in clay-slate, or killas, and _vice versâ_. the same observation applies to killas and the granitic porphyry called elvan. sometimes, in the same continuous vein, the granite will contain copper, and the killas tin, or _vice versâ_."[ -a] mr. fox, after ascertaining the existence at present of electric currents in some of the metalliferous veins in cornwall, has speculated on the probability of the same cause having acted originally on the sulphurets and muriates of copper, tin, iron, and zinc, dissolved in the hot water of fissures, so as to determine the peculiar mode of their distribution. after instituting experiments on this subject, he even endeavoured to account for the prevalence of an east and west direction in the principal cornish lodes by their position at right angles to the earth's magnetism; but mr. henwood and other experienced miners have pointed out objections to the theory; and it must be owned that the direction of veins in different mining districts varies so entirely that it seems to depend on lines of fracture, rather than on the laws of voltaic electricity. nevertheless, as different kinds of rock would be often in different electrical conditions, we may readily believe that electricity must often govern the arrangement of metallic precipitates in a rent. "i have observed," says mr. r. fox, "that when the chloride of tin in solution is placed in the voltaic circuit, part of the tin is deposited in a metallic state at the negative pole, and part at the positive one, in the state of a peroxide, such as it occurs in our cornish mines. this experiment may serve to explain why tin is found contiguous to, and intermixed with, copper ore, and likewise separated from it, in other parts of the same lode."[ -b] _relative age of the different metals._--after duly reflecting on the facts above described, we cannot doubt that mineral veins, like eruptions of granite or trap, are referable to many distinct periods of the earth's history, although it may be more difficult to determine the precise age of veins; because they have often remained open for ages, and because, as we have seen, the same fissure, after having been once filled, has frequently been re-opened or enlarged. but besides this diversity of age, it has been supposed by some geologists that certain metals have been produced exclusively in earlier, others in more modern times,--that tin, for example, is of higher antiquity than copper, copper than lead or silver, and all of them more ancient than gold. i shall first point out that the facts once relied upon in support of some of these views are contradicted by later experience, and then consider how far any chronological order of arrangement can be recognized in the position of the precious and other metals in the earth's crust. in the first place, it is not true that veins in which tin abounds are the oldest lodes worked in great britain. the government survey of ireland has demonstrated, that in wexford veins of copper and lead (the latter as usual being argentiferous) are much older than the tin of cornwall. in each of the two countries a very similar series of geological changes has occurred at two distinct epochs,--in wexford, before the devonian strata were deposited; in cornwall, after the carboniferous epoch. to begin with the irish mining district: we have granite in wexford, traversed by granite veins, which veins also intrude themselves into the silurian strata, the same silurian rocks as well as the veins having been denuded before the devonian beds were superimposed. next we find, in the same county, that elvans, or straight dikes of porphyritic granite, have cut through the granite and the veins before mentioned, but have not penetrated the devonian rocks. subsequently to these elvans, veins of copper and lead were produced, being of a date certainly posterior to the silurian, and anterior to the devonian; for they do not enter the latter, and, what is still more decisive, streaks or layers of derivative copper have been found near wexford in the devonian, not far from points where mines of copper are worked in the silurian strata.[ -a] although the precise age of such copper lodes cannot be defined, we may safely affirm that they were either filled at the close of the silurian or commencement of the devonian period. besides copper, lead, and silver, there is some gold in these ancient or primary metalliferous veins. a few fragments also of tin found in wicklow in the drift are supposed to have been derived from veins of the same age.[ -b] next, if we turn to cornwall, we find there also the monuments of a very analogous sequence of events. first the granite was formed; then, about the same period, veins of fine-grained granite, often tortuous (see fig. ., p. .), penetrating both the outer crust of granite and the adjoining fossiliferous or primary rocks, including the coal-measures; thirdly, elvans, holding their course straight through granite, granitic veins, and fossiliferous slates; fourthly, veins of tin also containing copper, the first of those eight systems of fissures of different ages already alluded to, p. . here, then, the tin lodes are newer than the elvans. it has indeed been stated by some cornish miners that the elvans are in some few instances posterior to the oldest tin-bearing lodes, but the observations of sir h. de la beche during the survey led him to an opposite conclusion, and he has shown how the cases referred to in corroboration can be otherwise interpreted.[ -a] we may, therefore, assert that the most ancient cornish lodes are younger than the coal-measures of that part of england, and it follows that they are of a much later date than the irish copper and lead of wexford and some adjoining counties. how much later it is not so easy to declare, although probably they are not newer than the beginning of the permian period, as no tin lodes have been discovered in any red sandstone of the poikilitic group, which overlies the coal in the south-west of england. there are lead veins in the mendip hills which extend through the mountain limestone into the permian or dolomitic conglomerate, and others in glamorganshire which enter the lias. those worked near frome, in somersetshire, have been traced into the inferior oolite. in bohemia, the rich veins of silver of joachimsthal cut through basalt containing olivine, which overlies tertiary lignite, in which are leaves of dicotyledonous trees. this silver, therefore, is decidedly a tertiary formation. in regard to the age of the gold of the ural mountains, in russia, which, like that of california, is obtained chiefly from auriferous alluvium, we can merely affirm that it occurs in veins of quartz in the schistose and granitic rocks of that chain. sir r. murchison observes, that no gold has yet been found in the permian conglomerates which lie at the base of the ural mountains, although large quantities of iron and copper detritus are mixed with the rolled pebbles of these same permian strata. hence it seems that the uralian quartz veins, containing gold and platinum, were not exposed to aqueous denudation during the permian era. but we cannot feel sure, from any data yet before us, that such auriferous veins of quartz may not be as old as the tin lodes of cornwall, in which, as well as the more ancient copper lodes of ireland, some gold has been detected. we are also unable at present to assign to the gold veins of brazil, peru, or california, their respective geological dates. but, although enough is known to show that ovid's line about the "age of gold," "aurea prima sata est ætas," would, by no means, be an apt motto for a treatise on mining, it would be equally rash in the present state of our inquiries to affirm, as some have done, that gold was the last-formed of metals. it has been remarked by m. de beaumont, that lead and some other metals are found in dikes of basalt and greenstone, as well as in mineral veins connected with trap rocks, whereas tin is met with in granite and in veins associated with the granitic series. if this rule hold true generally, the geological position of tin in localities accessible to the miners will belong, for the most part, to rocks older than those bearing lead. the tin veins will be of higher relative antiquity for the same reason that the "underlying" igneous formations or granites which are visible to man are older, on the whole, than the overlying or trappean formations. if different sets of fissures, originating simultaneously at different levels in the earth's crust, and communicating, some of them, with volcanic, others with heated plutonic masses, be filled with different metals, it will follow that those formed farthest from the surface will usually require the longest time before they can be exposed superficially. in order to bring them into view, or within reach of the miner, a greater amount of upheaval and denudation must take place in proportion as they have lain deeper when first formed. a considerable series of geological revolutions must intervene before any part of the fissure, which has been for ages in the proximity of the plutonic rocks, so as to receive the gases discharged from it when it was cooling, can emerge into the atmosphere. but i need not enlarge on this subject, as the reader will remember what was said in the th, th, and th chapters, on the chronology of the volcanic and hypogene formations. * * * * * _concluding remarks._--the theory of the origin of the hypogene rocks, at a variety of successive periods, as expounded in two of the chapters just cited, and still more the doctrine that such rocks may be now in the daily course of formation, has made and still makes its way, but slowly, into favour. the disinclination to embrace it has arisen partly from an inherent obscurity in the very nature of the evidence of plutonic action when developed on a great scale, at particular periods. it has also sprung, in some degree, from extrinsic considerations; many geologists having been unwilling to believe the doctrine of the transmutation of fossiliferous into crystalline rocks, because they were desirous of finding proofs of a beginning, and of tracing back the history of our terraqueous system to times anterior to the creation of organic beings. but if these expectations have been disappointed, if we have found it impossible to assign a limit to that time throughout which it has pleased an omnipotent and eternal being to manifest his creative power, we have at least succeeded beyond all hope in carrying back our researches to times antecedent to the existence of man. we can prove that man had a beginning, and that, all the species now contemporary with man, and many others which preceded, had also a beginning, and that, consequently, the present state of the organic world has not gone on from all eternity, as some philosophers have maintained. it can be shown that the earth's surface has been remodelled again and again; mountain chains have been raised or sunk; valleys formed, filled up, and then re-excavated; sea and land have changed places; yet throughout all these revolutions, and the consequent alterations of local and general climate, animal and vegetable life has been sustained. this has been accomplished without violation of the laws now governing the organic creation, by which limits are assigned to the variability of species. the succession of living beings appears to have been continued not by the transmutation of species, but by the introduction into the earth from time to time of new plants and animals, and each assemblage of new species must have been admirably fitted for the new states of the globe as they arose, or they would not have increased and multiplied and endured for indefinite periods.[ -a] astronomy had been unable to establish the plurality of habitable worlds throughout space, however favourite a subject of conjecture and speculation; but geology, although it cannot prove that other planets are peopled with appropriate races of living beings, has demonstrated the truth of conclusions scarcely less wonderful,--the existence on our own planet of so many habitable surfaces, or worlds as they have been called, each distinct in time, and peopled with its peculiar races of aquatic and terrestrial beings. the proofs now accumulated of the close analogy between extinct and recent species are such as to leave no doubt on the mind that the same harmony of parts and beauty of contrivance which we admire in the living creation, has equally characterized the organic world at remote periods. thus as we increase our knowledge of the inexhaustible variety displayed in living nature, and admire the infinite wisdom and power which it displays, our admiration is multiplied by the reflection, that it is only the last of a great series of pre-existing creations, of which we cannot estimate the number or limit in times past.[ -b] footnotes: [ -a] principles, &c. chap. iv. th ed. p. . [ -a] geol. trans. vol. iv. p. .; trans. roy. geol. society cornwall, vol. ii. p. . [ -a] carne, trans. of geol. soc. cornwall, vol. iii. p. . [ -b] fournet, etudes sur les dépots metalliferes. [ -a] geol. rep. on cornwall, p. . [ -b] principles, ch. xxvii. th ed. p. . [ -a] see dr. daubeny's volcanos. [ -b] bulletin, iv. p. . [ -a] r. w. fox on mineral veins, p. . [ -b] ibid. p. . [ -a] i am indebted to sir h. de la beche for this information. see also maps and sections of irish survey. [ -b] sir h. de la beche, ms. notes on irish survey. [ -a] report on geology of cornwall, p. . [ -a] see principles of geol., book . [ -b] see the author's anniv. address to the geol. soc. . proceedings of g. s. no. . p. . index. a. Ægean sea, mud of, . animal life in depths of, . agassiz, m., cited, . . . . . . on parallel roads, . on fossil fishes of molasse and faluns, . on fossil fish of lias, . on fossil fish in permian marl-slate, . on fish from sheppey, . on foot-prints, . on fishes of brown coal, . on glaciers, . . age of formation determined by fragments of older rock, . of metamorphic rocks, . test of, in plutonic rocks by relative position, . of spanish volcanos, . of volcanic rocks, how tested, - . aix-la-chapelle, hot spring at, . alabaster defined, . alabama, cretaceous shingle of, . alberti on the keuper, . alexander, capt., marine shells in crag, found by, . alluvium, term explained, . in auvergne, . of the wealden, . alps, nummulitic formation of, . curved strata of, . swiss and savoy, cleavage of, . of switzerland, . alpine blocks on the jura, . erratics, . altered rocks, . . by subterranean gases, . alternations of rocks, . of marine and freshwater formations, . alumine in rocks, . _amblyrhynchus cristatus_, . america, north, lithodomi in beaches of, . south, cretaceous strata, . south, gradual rise of parts of, . south, fossils of, . amygdaloid, . amphitherium, . andelys, chalk cliffs at, . andernach, strata near, . andes, plutonic rocks of, . rocks drifted from to chiloe, . anthracite in rhode island, . anticlinal line, . . antrim, rocks altered by dikes in, . antwerp, strata like suffolk crag near, . _apateon pedestris_, a carboniferous reptile, . apennines, limestone in, . appalachian coal-field, . appalachians, altered rocks in, . _apteryx_ in new zealand, . aqueous rocks defined, . rocks, mineral character of, . deposits, superposition of, . arbroath, section from, to the grampians, . archegosaurus, figure of, . archiac, m., cited, . on fossils in chalk, . on shells in french lower eocene, . ardèche, lava in, . arenaceous rocks described, . argillaceous rocks, . schist, . argile plastique, or lower eocene, . argyleshire, trap-vein in cliff, . arran, age of granite in, . section of, . dike of greenstone in, . arthur's seat, altered strata of, . ashby-de-la-zouch, fault in coal-field of, . ascension, lamination of volcanic rocks in, . asterophyllites, . asti, formations at, . atherfield, cretaceous strata of, . augite, . aurillac, freshwater strata of, . austen, mr., r. a. c., on phosphate of lime, . australian cave-breccias, . auvergne freshwater formations, . succession of changes in, . lacustrine strata, . mineral veins of, . indusial limestone, . extinct volcanos of, . alluvium in, . aymestry limestone, . b. bagshot sands, . bacillaria, fossil in tripoli, . baiæ, bay of, strata in, . bakewell, mr., on cleavages of alps, . balgray, near glasgow, stumps of trees in coal, . bahia blanca, fossil remains at, . baltic, brackish water strata on coast of, . barcombe, chalk flints near, . barton cliff, . barrande, m., on trilobites, . basterot, m. de, on tertiaries of south of france, . basalt, . columnar in the eifel, . columnar, near vicenza, . columnar, structure of, . basset, term explained, . batrachian, eggs of, in old red, scotland, postscript, x. bayfield, capt., on fossil shells in canada, . on inland cliffs in gulf of st. lawrence, . bean, mr., shells similar to those in norwich crag found in yorkshire by, . bean, mr., on fossil shells from oolite, . beachy head, chalk cliffs near, . beaumont, m. e. de, on rocks of hautes alpes, . on lamination of volcanic rocks, . beaumont, m. e. de, on swiss alps, . on quartz, . on oolite formation in france, . beck, dr., on kelp, . on graptolites, . cited, . . belemnite in oxford clay, . berger, dr., on rocks altered by dikes, . bergmann on trap, . berlin, tertiary strata near, . bermuda islands, lagoons in, . rocks of, . bernese alps, gneiss in, . berthier, on augite and hornblende, . beudant, m., on hungary, . beyrich, prof., on tertiary strata near berlin, . biaritz, calcareous cliffs of, . bilin, tripoli, composed of infusoria, . binney, mr., on stigmaria and sigillaria, . birds, footprints of, . fossil, scarcity of, postscript, xix. bischoff, prof., experiments on heat, . on steam at a high temperature, . blainville, on number of genera of mollusca, . boase, dr., cited, . boblaye, m., on inland cliffs, . cited, . bog-iron ore, . borrowdale, black-lead of, . bordeaux, tertiary deposits of, . bosquet, m., on maestricht beds, . bothnia, gulf of, land upheaved, . boué, m., on arrangement of rocks, . on fossil shells in hungary, . on carrara marble, . on swiss alps, . bonelli, on strata in italy, . boulder formation in canada, . period, fauna of, . formation, mineral ingredients of, . formation in england, . boulders, . striated, . boutigny, m., cited, . bowen, lieut. a., r.n., drawings of rocks in gulf of st. lawrence, . bowerbank, mr., on fossil flora of sheppey, . bowman, mr., on coal-seams, . bracklesham bay, characteristic shells of, . brash, term, explained, . bravard, m., on auvergne mammalia, . . breccia on ancient coast lines, . brickenden, captain, on elgin fossils, postscript, ix. brighton, elephant bed of, . bristol, dolomitic conglomerate near, . section of strata near, . brocchi, on subapennines, . . brockedon, mr., on black-lead, . broderip, mr., cited, . brodie, rev. p.b., on fossil insects, . cited, . bromley, oyster-bed near, . brongniart, m. adolphe, on eocene flora, . on flora of cretaceous period, . on fossil plants in lias, . on plants of bunter sandstein, . on fossil fir-cones, . on permian flora, . on sigillaria, . on asterophyllites, . on stigmaria, . age of acrogens, . on endogens, . brongniart, m. alex., on paris tertiaries, . on eocene formation, . on shells of nummulitic formation, . on coal mine near lyons, . brora, coal formation, . brora, granite near, . brown, mr. richard, on stigmariæ, . on coal formation, . on cape breton coal-field, . . on carboniferous rain-prints, postscript, xii. buckland, dr., on cave at kirkdale, . on coal plants, . on coprolites in chalk, . on fish of lias, . on footprints, . on mountains of caernarvonshire, . on oyster bed near bromley, . on parallel roads, . on term poikilitic, . on saurians of lias, . on sudden destruction of saurians, . cited, . . . . . buddle, mr., on creeps in coal mines, . on ancient river-channels of coal period, . buist, dr. g., on saltness of red sea, . bunbury, mr. c. j. f., on plants of coal-field, . bunter sandstein, . burmeister on trilobites, . burnes, sir a., cited, . c. caernarvonshire, ancient glaciers of, . calamites, figures of, . near pictou, . calcaire grossier, . siliceux, . calcareous rocks, . rocks of gulf of spezia, . cliffs of biaritz, . caldcleugh, mr., cited, . caldera of palma, . cambrian group, . volcanic rocks, . campagna di roma, tuffs of, . canada, shells in drift of, . cantal, freshwater formation of, . igneous rocks of, . freshwater beds of, . cape breton, coal measures of, . wrath, granite veins in, . caradoc sandstone, . carbonaceous shale, . carbonate of lime scarce in metamorphic rocks, . carbonate of lime in rocks, how tested, . carboniferous group, . flora, . period, plutonic rocks of, . period, volcanic rocks of, . reptiles, . carne, mr., on cornish lodes, . . carrara marble, . _caryophyllia cæspitosa_, bed of, in sicily, . castrogiovanni, bent strata near, . catalonia, volcanic region of, . cautley, captain, on sewâlik hills, . caves in europe, . at kirkdale, . in sicily, . in australia, . central france, upper eocene of, . cetacea, fossil, rarity of, postscript, xxi. chalk, pinnacle of, near sherringham, . of faxoe, . and postscript, xv. white, fossils of, . white, section of, . white, extent and origin of, . white, animal origin of, . pebbles in, . difference of, in north and south of europe, . chalk cliffs, inland, on seine, . needles of, in normandy, . flints, bed of, near barcombe, . chambers, mr., cited, . chamisso, cited, . chara, in freshwater strata, . in flints of cantal, . in eocene strata of france, . in purbeck beds, . charlesworth, mr. e., cited, on crag, . charpentier, m., on alpine glaciers, . on swiss glaciers, . cheirotherium, footprints of, . . chemical and mechanical deposits, . chili, earthquake in, . gold mines in, . chiloe, rocks drifted from andes to, . chlorite schist, . christiania, dike near, . trap rocks, passage of granite into, at, . granite near, . gneiss near, . intrusion of granite into beds near, . chronological groups, . cinder-bed, purbeck, . claiborne, marine shells of, . clausen, mr., cited, . clay, defined, . clay-slate, . . clay-ironstone, . clays, plastic, . cleavage of rocks, . climate of drift period, . of coal period, . coal, zigzag flexures of, near mons group, . measures, . . how formed, . pipes, danger of, . mine, near lyons, . seam at brownsville, pennsylvania, view of, . conversion of into lignite, . formation at brora, . seams, continuity of, . period, climate of, . strata, footprints of reptiles in, . coal-field at burdiehouse, . of ashby-de-la-zouch, . united states, diagram of, . of yorkshire, fossils of, . coalbrook dale, beetles in coal of, . fossil cones in, . coal measures of, . faults in, . cockfield fell, rocks altered by dikes, . columbia, vinegar river of, . colchester, mr., on mammalian remains at kyson, . côme, ravine in lava of, . cones in val di noto, . and craters, absence of, in england, . and craters, . conifers, fossil trees, . concretionary structure, . conglomerate, or pudding-stone, . dolomitic, . vertical in scotland, &c., . connecticut, valley of the, . beds, antiquity of, . conrad, mr., on cretaceous rocks, . conybeare, mr., cited, . . . . on plesiosaurus, . on oolite and lias, . on term poikilitic, . on crocodiles, . cook, capt., on _fucus giganteus_, . coprolites in chalk, . coralline crag, fossils in, . coral islands and reefs, . . rag of oolite, . corals, figures of, in crag, . of devonian system, . of devonian strata in united states, . in wenlock formation, . corinth, corrosion of rocks by gases near, . cornbrash, . cornwall, granite veins in, . . mineral veins in, . . tin of, newer than irish copper, . cotta, dr. b., on granite in saxony, . crag coralline, fossils in, . comparison of faluns and, . of suffolk, red and coralline, . . fluvio-marine, norwich, . craigleith fossil trees, . quarry, slanting tree in, . crater of island of st. paul, . craven fault, . creeps in coal-mines described, . credneria in quadersandstein, postscript, xvi. cretaceous rocks of pyrenees, . group, . . and postscript, xvi. strata in south america and india, . period, plutonic rocks of, . volcanic rocks, . rocks in united states, . crocodiles near cuba, . croizet, m., on auvergne fossil mammalia, . cromer, contorted drift near, . "crop out," term explained, . crust of earth defined, . crystalline limestone, . rocks, erroneously termed primitive, . schists defined, . curved strata, . strata, experiments to illustrate, . cutch, runn of, . cuvier, m., on eocene formation, . on amphitherium, . cited, . on tertiary strata near paris, . on fossils of montmartre, . cyclopian islands, . cypris in lias, . in wealden, . in marl of auvergne, . cystideæ in silurian rocks, . d. dana, mr., on coprolites of birds, . on coral reef in sandwich islands, . on volcanos of sandwich islands, . . . dartmoor, granite of, . darwin, mr., cited, . on boulders and glaciers in south america, . on cleavage in south america, . on coral islands of pacific, . on dike in st. helena, . on habits of ostrich, . and postscript, xx. on fossils in south america, . on _fucus giganteus_, . on gradual rise of part of s. america, . on lamination of volcanic rocks, . on parallel roads, . on plutonic rocks of andes, . on recent strata near lima, . on saurians in galapagos islands, . on sinking of coral reefs, . on welsh glaciers, . daubeny, dr., on the solfatara, . daubeny, dr., on volcanos in auvergne, . dax, inland cliff at, . deane, dr., on footprints, . dean, forest of, coal in, . dechen, prof. von, on reptiles in saarbrück coal-field, . de koninck, cited, . . de la beche, sir h., cited, . . . on carrara marble, . on clay beds, . on clay-ironstone, . on coal-measures near swansea, . on fossil trees, s. wales, . on granite of dartmoor, . on mineral veins, . . . on term supracretaceous, . on trap of new red sandstone period, . deluge, . denudation explained, . of the weald valley, . terraces of, in sicily, . derbyshire, lead veins of, . deshayes, m., identification of shells, . on fossil shells in hungary, . on lower eocene shells, . on tertiary classification, . desmarest, cited, . on trappean rocks, . desnoyers, m., on faluns of touraine, . desor, m., on glacial fauna in n. america, . devonian flora, . strata in united states, . system, term explained, . diagonal, or cross stratification, . dicotyledonous leaves in chalk, postscript, xvi. dike in st. helena, . dikes at palagonia in sicily, . trappean, crystalline in centre, . defined, . in scotland, . of somma, . diluvium, popular explanation of term, . dip, term explained, . dolerite, or greenstone, . dolomite defined, . dolomitic conglomerate, . doue, m. b. de, on volcanos of velay, . drift contorted, near cromer, . in ireland, . in norfolk, . meteorites in, . northern, in scotland, . northern, in north wales, . of scandinavia, north germany, and russia, . period, climate of, . period, subsidence in, . shells in canada, . dudley limestone, . shales of coal near, . dufrénoy, m., on granite of pyrenees, . duff, mr. p., on reptile of old red, postscript, ix. on hill of gergovia, . dunker, dr., on wealden of hanover, . e. echinoderms of coralline crag, . echinus, figure of, . egerton, mr., on fossils of southern india, . egerton, sir p., on fish of marl slate, . on fossil fish of connecticut beds, . on fossils of isle of wight, . on saurians and fish in new red sandstone, . on ichthyosaurus, . eggs, fossil, of snake, . ehrenberg, prof., on bog-iron ore, . on infusoria, . elephant bed, brighton, . _elephas primigenius_, jaw figured, . elvans of ireland and cornwall, . term explained, . encrinites, figure of, . endogens, . eocene, foraminifera, . formations, . formations in england, . granite, . lower, in france, - . middle, in france, . strata, in united states, . upper, near louvain, . term defined, . upper, of central france, . volcanic rocks, . equisetaceæ, . equisetum of virginian oolite, . _equisetum_ giganteum, . erman on meteoric iron in russia, . erratics, alpine, . northern origin of, . escher, m., on boulders of jura, . etna, deposits of, . eurite, . euritic porphyry described, . exogens, . f. faluns of touraine, . . faluns, comparison of, and crag, . falconer, dr., on sewâlik hills, . falkland islands, . farnham, phosphate of lime near, . fault, term explained, . faults, origin of, . faxoe, chalk of, . and postscript, xv. felixstow, remains of cetacea found near, . felspar, . ferns in coal-measures, . fife, altered rock in, . fifeshire, trap dike in, . megalichthys found in cannel coal in, . fishes, fossil, of upper cretaceous, . of old red sandstone, . of wealden, . fossil, of brown coal, . fissures filled with metallic matter, . _see_ mineral veins. fitton, dr., on division of lower cretaceous formation, . cited, . . . . . . fleming, dr., on scales of fish in old red, . on trap-rocks in coal-field of forth, . on trap dike in fifeshire, . flora, carboniferous, . cretaceous, . devonian, . of london clay, . permian, . . flötz, term explained, . flysch, explanation of term, . footprints of birds, . and postscript, xx. of reptilians, . fossil, . . . . foraminifera in chalk, . eocene, . forbes, prof. e., on caradoc sandstone, . on cystideæ, . on shells in crag deposits, . on cretaceous fossil shells, . on fossils of the faluns, . on fossils in drift in south ireland, . on deep-sea origin of silurian strata, . on echinoderms of coralline crag, . on fauna of boulder period, . on migrations of mollusca in glacial period, . on fossils of purbeck group, . . on strata at atherfield, . on changes of wealden testacea, . on volcanic rocks of oolite period, . on depth of animal life in Ægean, . . cited, . forbes, prof. james, on zones in volcanic rocks, . on the alps, . forchhammer, on scratched limestone, . forest, fossil, in norfolk, . . forfarshire, old red sandstone in, . formation, term defined, . fossil, term defined, . fossils of chalk and greensand, figures of, . in chalk at faxoe, . of coralline crag, . of devonian system, . and postscript, x. xi. of eocene strata in united states, . in faluns of touraine, . freshwater and marine, . of isle of wight, . of lias, . of ludlow formation, . of mountain limestone, . of london clay, . of maestricht beds, . of lower greensand, . of new red sandstone, . and postscript, xiii. of oolite, . . of red crag, . of silurian rocks, . and postscript, vii. of solenhofen, . of upper greensand, . of wealden, . test of the age of formations, . fossil fish of permian limestone, . of connecticut beds, . of richmond, u. s., strata, . of old red sandstone, . scales of permian, figured, . footsteps, . . . ferns in carbonaceous shale, . forest in nova scotia, . forest near wolverhampton, . forest in isle of portland, . plants in wealden, . plants of lias, . plants of bunter sandstein, . trees erect, . wood, petrifaction of, . wood perforated by teredina, . remains in caves, . shells from etna, . shells near grignon, . shells of mayence strata, . shells in virginia, . fossiliferous strata, tabular view of, . fournet, m., on mineral veins of auvergne, . on disintegration of rocks, . on quartz, . fox, mr. r. w., . on cornish lodes, . fox, rev. mr., on extinct quadrupeds of isle of wight, . freshwater beds of isle of wight, . deposits in valley of thames, . land shells numerous in, . freshwater formations of auvergne, . freshwater formation, how distinguished from marine, . . . remains of fish in, . associated with norfolk drift, . chara in, . cypris in, . freshwater shells in brown coal near bonn, . _fucus giganteus_, . _vesiculosus_, growth of, in jutland, . _vesiculosus_ in lym-fiord, . fundy, bay of, impressions in red mud of, . g. gaillonella fossil in tripoli, . ferruginea in bog-iron ore, . galapagos islands, animals of, . garnets in altered rock, . gases, subterranean rocks altered by, . gault, . gavarnie, flexures of strata, . geology defined, . gergovia, hill of, . giant's causeway, columns at, . gibbes, r. w., cited, . glacial phenomena, northern, origin of, . glaciers, alpine, . glaciers on caernarvonshire mountains, . glasgow, marine strata near, . glen roy, parallel roads of, . glen tilt, granite of, . gneiss, altered by granite, . in bernese alps, . at cape wrath, . near christiania, . described, . gold, age of, in ireland, . age of, in ural mountains, . goldfuss, prof., on reptiles in coal-field, . göppert, prof., on beds of coal, . on petrifaction, . graham's island, . . grampians, old red conglomerates in, . granite described, . . . . passage of into trap, . porphyritic, . and limestone, junction of in glen tilt, . syenitic, . talcose, . schorly, . of cornwall and dartmoor, . of swiss alps, . rocks in connection with mineral veins, . of saxony, . granites, oldest, . varieties of, . veins in cornwall, . veins in cape wrath, . veins in table mountain, . vein in white mountains, . of arran, age of, . near christiania, . dikes in mount battock, . graphite, powder of, consolidated by pressure, . graptolites, . grateloup, m., on fossils in chalk, . grauwacke, term explained, . greenland, sinking of coast, . greensand, upper, . fossils of, . greensburg, pennsylvania, footprints of reptile in coal strata at, . greenstone or dolerite, . dike of, in arran, . grès de beauchamp, paris basin, . grignon, fossil shells near, . grit defined, . guadaloupe, human skeleton of, . guidoni on carrara marble, . gutbier, col. von, on permian flora, . . gryphæa, fossil figure of, . gypseous marls, . series, . gypsum defined, . h. hall, sir jas., experiments on fused minerals, . on curved strata, . capt. b., cited, . . . hamilton, sir w., on eruption of vesuvius, . harris, major, on salt lake in ethiopia, . hartz, bunter sandstein of, . hastings, lady, fossils collected by, . hastings sand, . bed, shells of, . hautes alpes, rocks of, . haüy cited, . hawkshaw, mr., on fossil trees in coal, . hayes, t. l., on icebergs, . hébert, m., cited on upper eocene beds, . hebrides, dikes of trap in, . heidelberg, varieties of granite near, . henfrey, mr. a., on food of mastodon, . henslow, prof., on fossil cetacea in suffolk, . on fossil forests, . on dike and altered rock near plas newydd, . henry, mr., cited, . herschel, sir j., on slaty cleavage, . hertfordshire pudding-stone, . hibbert, dr., on volcanic rocks, . on coal field at burdiehouse, . cited, . high teesdale, garnets in altered rock at, . hildburghausen, footprints of reptile at, . . hippurite limestone, . hitchcock, prof., on footprints, . hoffmann, mr., on lipari islands, cited, . on cave near palermo, . on carrara marble, . hooghly river, analysis of water, . hopkins, mr., on fractures in weald, . horizontality of strata, . of roads of lochaber, . hornblende, . schist, . . horner, mr., on geology of eifel, . on megalichthys, . hubbard, prof., on granite vein in white mountains, . hugi, m., on swiss alps, . humboldt, cited, . on uniform character of rocks, . hungary, trachyte of, . volcanic rocks of, . hunt, mr., experiments on clay-ironstone, . hutton, opinions of, . huttonian theory, . hypogene, term defined, . rocks, mineral character of, . or metamorphic limestone, . i. ibbetson, capt., on chalk isle of wight, . ice, rocks drifted by, . icebergs, stranding of, . . iceland, icebergs drifted to, . ichthyolites of old red sandstone, . _ichthyosaurus communis_, figure of, . igneous rocks, . of siebengebirge and westerwald, . rocks of val di noto, . _iguanodon mantelli_, . . india, cretaceous system in, . freshwater deposits of, . oolitic formation in, . indusial limestone, auvergne, . infusoria in tripoli, . inland sea-cliffs in south of england, . insects in lias, . ireland, drift in, . ischia, volcanic cones in, . post-pliocene strata of, . isle of wight, freshwater beds of, . isomorphism, theory of, . j. jackson, dr. c. t., analysis of fossil bones, . james, capt., on fossils in drift south ireland, . java, stream of sulphureous water, . jobert, m., on hill of gergovia, . joints, . jorullo, lava stream of, . jura, alpine blocks on, . limestone, . structure of, . k. kangaroo, fossil and recent, jaws figured, . kaup, prof., on footprints of cheirotherium, . kaye, mr., on fossils of southern india, . keeling island, fragment of greenstone in, . keilhau, prof., cited, . . on dike of greenstone, . on gneiss near christiania, . on granite, . kelloway rock, . kentish chalk, sand-galls in, . keuper, the, . killas in granite of cornwall, . kimmeridge clay, . and postscript, xxi. king, dr., on footprints of reptile, . king, mr., on permian group and fossils, . . kirkdale, cave at, . kotzebue cited, . kyson, in suffolk, strata of, . l. labyrinthodon, . . . lacustrine strata of auvergne, . lagoons at mouth of rivers, . of bermuda islands, . lake craters of eifel, . crater of laach, . lamarck on bivalve mollusca, . land, rising and sinking, . laterite, . lava, . current, auvergne, . relation to trap, . stream of jorullo, . of stromboli, . lea, mr., footprints of reptile discovered by, . lead, veins of, in permian rocks, . lehman on classification of rocks, . leibnitz, theory of, . lepidodendra, . lewes, coomb near, . lias, . period, volcanic rocks, . at lyme regis, . plutonic rocks of, . and oolite, origin of, . fossil plants of, . liebig, prof., on conversion of coal into lignite, . on preservation of fossil bones in caverns, . lima, recent strata of, . limagne d'auvergne, freshwater formations of, . lime, scarcity of, in metamorphic rocks, . limestone, brecciated, . crystalline, . compact, . fossiliferous, . hippurite, . indusial, auvergne, . of jura, . magnesian, . mountain fossils of, . primary or metamorphic, . in germany, of devonian system, . lindley, dr., cited, . on leaves in lignite, . link, m., on footprints, . lipari islands, rocks altered by gases in, . lisbon, marine tertiary strata near, . lithodomi in beaches of n. america, . in inland cliffs, . llandeilo flags, . loam defined, . lochaber, parallel roads of, . lodes. _see_ mineral veins, . loess of valley of rhine, . fossil land shells of, figured, . logan, mr., on coal measures of south wales, . on fossil forest in nova scotia, . on reptilian foot-prints in lowest silurian in canada, postscript, viii. london clay, . lonsdale, mr., cited, .; on corals, . on corals of normandy, . on corals in wenlock formation, . on fossils in white chalk, . on old red sandstone of s. devon, . on stonesfield slate, . louvain, eocene strata near, . lovén on shells of norway, . ludlow formation, . lund, cited, . lycett, mr., on shells of oolite, . lyme regis, lias at, . lym-fiord invaded by the sea, . kelp in, . lyons, coal mine near, . m. macacus, in eocene formation, . maclaren, mr., on erratic blocks in pentlands, . maclure, dr., on volcanos in catalonia, . macculloch, dr., cited, . on altered rock in fife, . on basaltic columns in skye, . on denudation, . on granite of aberdeenshire, . on igneous rocks of scotland, . on isle of skye, . . on hornblende schist, . on overlying rocks, . on parallel roads, . on pebbles of granite, . on trap vein in argyleshire, . madeira, view of dike in inland valley in, . maestricht beds, . magnesian limestone, concretionary structure of, . defined, . groups, . maidstone, fossils in white chalk of, . mammalia, extinct, above drift in united states, . extinct, of basin of mississippi, . fossil teeth of, figured, . mammat's "geological facts" cited, . mammifer in trias near stuttgart, postscript, xiii. mansfield in thuringia, permian formation at, . mantell, dr., cited, . . . . on belemnite, . on chalk flints, . on brighton elephant bed, . on freshwater beds of isle of wight, . on iguanodon, . on wealden group, . on reptile in old red, postscript, x. marble defined, . marl defined, . in lake superior, . red and green in england, . marl-slate defined, . martin, mr., cited, . on cross fractures in chalk, . martins, mr. c., on glaciers of spitzbergen, . map to illustrate denudation of weald, . map of eocene beds of central france, . massachusetts, plumbago in, . _mastodon angustidens_, jaw, figure of, . _mastodon giganteus_, in united states, . mayence tertiary strata, . mediterranean and red sea, distinct species in, . deposits forming in, . megalichthys in cannel coal of fifeshire, . megatherium in south america, . menai straits, marine shells in drift, . mendips, denudation in, . metalliferous veins. _see_ mineral veins. metals, supposed relative ages of, . metamorphic rocks, . defined, . why less calcareous than fossiliferous, . order of succession, . glossary of, . metamorphic strata, origin of, . metamorphic structure, origin of, . meteorites in drift, . mexico, lamination of volcanic rocks in, . meyer, m. h. von, cited, . on fossil mammalia of rhine, . on reptile in coal, . . on sandstone of vosges, . on wealden of hanover and westphalia, . mica schist, . micaceous sandstone, origin of, . microlestes antiquus, triassic mammifer, postscr., xiv. miller, mr. h., on origin of rock salt, . on old red sandstone, . on fossil trees of coal near edinburgh, . minchinhampton, fossil shells at, . mineral character of aqueous rocks, . composition, test of age of volcanic rocks, . springs, connected with mineral veins, . veins and faults, . . of different ages, . . . veins, pebbles in, . subsequently enlarged and re-opened, . veins, various forms of, . veins near granite, . mineralization of organic remains, . miocene formations, . in united states, . period, volcanic rocks of, . term defined, . mississippi, fluviatile strata and delta of, . . mitchell, sir t., on australian caves, . mitscherlich, prof., on augite and hornblende, . on isomorphism, . on mineral composition of somma, . modon, lithodomi in cliff at, . molasse of switzerland, . mons, flexures of coal at, . mont blanc, granite of, . mont dor, auvergne, . monte calvo, section of, . montlosier, m., on auvergne volcanos, . moraine, term explained, . moraines of glaciers, . morea, inland sea-cliffs of, . trap of, . morris, mr., cited, . on fossils at brentford, . morton, dr., on cretaceous rocks, . morven, basaltic columns in, . mosasaurus in st. peter's mount, . mountain limestone, fossils of, . munster, count, on fossils of solenhofen, . murchison, sir r., cited, . . on new red sandstone, . on age of alps, . on age of gold in russia, . on erratic blocks of alps, . on granite, . . on primary strata in russia, . on joints and cleavage, . . on old red sandstone of s. devon, . . on pentamerus, . on permian flora, . on silurian strata of shropshire, . on swiss alps, . on term permian, . on term silurian, . on tilestones, . muschelkalk, . n. naples, post-pliocene formations near, . recent strata near, . navarino, lithodomi found in cliff at, . necker, m. l. a., cited, . on composition of cone of somma, . on granite in arran, . on granitic rocks, . on swiss alps, . terms granite underlying, . nelson, lieut., drawing of bermuda, . on bermuda island, . neptunian theory, . newcastle coal field, great faults in, . newcastle, fossil tree near, . . new jersey, _mastodon giganteus_ in, . new red sandstone, distinction from old, . its subdivisions, . of united states, . trap of, . new zealand, absence of quadrupeds, . niagara, recent shells in valley of, . noeggerath, m., cited, . nomenclature, changes of, . norfolk, buried forest, . . . drift, . normandy chalk, cliffs, and needles, . northwich, beds of salt at, . norwich crag, fluvio-marine, . sand-pipes near, . nova scotia, coal seams of cape breton, . fossil forest of coal in, . nummulites, figures of, . . nummulitic formation, . nyst, m., cited, . o. oeynhausen, m. von, on cornish granite veins, . olot, extinct volcanos near, . old red sandstone, . in forfarshire, . trap of, . oolite, . and lias, origin of, . inferior, fossils of, . in france, . plutonic rocks of, . term defined, . volcanic rocks of, . oolitic group in france, . orbigny, m. d', cited, . on fossils of nummulitic limestone, . on subdivisions of cretaceous series, . organic remains, criterion of age of formation, . test of age of volcanic rocks, . ormerod, mr., on trias of cheshire, . overlying, term applied to volcanic rocks, . owen, prof., cited, . . . . . . . on amphitherium, . on birds in new zealand, . on caves in england, . on footprints, . on fossils in australia, . on fossil monkey, . on fossil quadrupeds, . on ichthyosaurus, . on reptile in coal, . on serpent of bracklesham, . on snake at sheppey, . on thecodont saurians, . on zeuglodon, . . on reptile in silurian rocks, postscript, viii. oxford clay, . oyster beds, . p. pacific, coral reefs of, . palæontology, term explained, . palagonia, dikes at, . _paleotherium magnum_, figure of, . tooth of, . palermo, caves near, . palma, isle of, map and view of, . parallel roads, . pareto, m., on carrara marble, . paris basin, . parkinson, mr., on crag, . parrot, dr. f., on salt lakes of asia, . pebbles in chalk, . pegmatite, . _pentamerus knightii_, . pentland hills, mr. maclaren on, . pepys, mr., cited, . permian flora, distinct from coal, . formation in thuringia, . group, term explained, . petrifaction of fossil wood, . petrifaction, process of, . philippi, dr., on fossil shells near naples, . on marine shells in caves of sicily, . on tertiary shells of sicily, . phillips, prof., cited, . . on cleavage, . on terminology, . phillips, mr. w., on kaolin of china, . phosphate of lime, . phryganea, figure of, . indusiæ of, . pictou, nova scotia, calamites near, . pilla, m., on age of carrara marble, . planitz, tripoli of, . plas newydd, rock altered by dike near, . plastic clays, . playfair, cited, . . . on faults, . on huttonian theory of stratification, . plesiosaurus, figure of, . plieninger, professor, on triassic mammifer, postscript, xiii. pliocene, newer period, . newer, strata, . strata in sicily, . older, in united states, . strata, . period, volcanic rocks of, . . term defined, . plomb du cantal, described, . plumbago in massachusetts, . plutonic rocks, . . age of, . of carboniferous period, . of oolite and lias, . recent and pliocene, . of silurian period, . age, how tested, . plutonic and sedimentary rocks, diagram of, . poggendorf, cited, . poikilitic formation, . term explained, . pomel, m., on mammalia of auvergne, . . ponza islands, structure of, . . porphyritic granite, . porphyry, . portland, isle of, fossil forest in, . portland stone, . post-pliocene formations, . period, volcanic rocks, . potsdam sandstone, reptilian, postscript, vii. xviii. pottsville, coal seams near, . footprints of reptile near, . pozzolana, . pratt, mr., on ammonites, . on extinct quadrupeds of isle of wight, . predazzo, altered rocks at, . prestwich, mr., cited, . on english eocene strata, . . . on coal measures of coalbrook dale, . . prevost, m. c., on paris basin, . . . progressive development, theory of, postscript, xvi. psaronites in germany and france, . pumice, . purbeck beds, . puy de tartaret, . puy de pariou, . puzzuoli, elevation and depression of land at, . pyrenees, cretaceous rocks of, . curvatures of strata, . granite of, . nummulitic formation of, . q. quadrumana fossil, postscript, xvii. quarrington hill, basaltic dike near, . quartz, . quartzite, or quartz rock, . r. radnorshire, stratified trap of, . rain-prints, fossil in coal shale, postscript, xii. ramsay, prof. a. c., on denudation, . on granite in arran, . on section near bristol, . on welsh glaciers, . recent strata defined, . near naples, . redfield, mr., on glacial fauna in america, . on fossil fish, . red sandstone, origin of, . red sea and mediterranean, distinct species in, . red sea, saltness of, . reptiles, carboniferous, . . of lias, . fossil eggs of, . reptile, in lower silurian, postscript, vii. in old red sandstone of morayshire, postscript, ix. rhine, valley, loess of, . ripple-mark, formation of, . river channels, ancient, . river, excavation through lava by, . terraces, . rock, term defined, . rocks, four classes of, contemporaneous, . classification of, . composed of fossil zoophytes and shells, . trappean, . roderberg, extinct volcano of, . rogers, prof. h. d., on coal field, united states, . cited, . on reptilian footprints in coal, postscript, xi. rogers, prof. w. b., on oolitic coal field, united states, . . rome, formations at, . römer, f., on chalk in texas, . m. f. a., on flora of hartz, . rose, prof. g., cited, . . on hornblende, . rosenlaui, limestone scratched by glacier of, . ross, captain, on greenstone in keeling island, . ross-shire, denudation in, . rothliegendes, lower, or permian, . rozet, m., cited, . rubble, term explained, . russia, erratic blocks in, . fossil meteoric iron in, . permian rocks in, . s. saarbrück coal field, reptile found in, . st. abb's head, curved strata near, . st. andrews, trap rocks in cliffs near, . . st. helena, basalt in, . . st. lawrence, gulf of, inland beaches and cliffs, . st. mihiel, inland cliffs near, . st. paul, island of, . st. peter's mount, maestricht, fossils in, . sand-pipes in, . salisbury crag, altered strata of, . salt rock, origin of, . precipitation of, . at northwich, . lakes of asia, . salter, mr., on fossil of caradoc sandstone, . sand-pipes near maestricht, . or sand-galls, term explained, . near norwich, . sandstone, siliceous, . with cracks in wealden, . sandwich islands, coral reef in, . volcanos of, . . . saurians of lias, . thecodont, . saussure, m., on moraines, . on vertical conglomerates, . savi, m., on carrara marble, . saxony, granite in, . schist, hornblende, and mica, . . argillaceous, . chlorite, . schorl rock and schorly granite, . scoresby on icebergs, . scoriæ, . scotland, carboniferous traps of, . northern drift in, . old red sandstone of, . scrope, mr., cited, . . . . . . . on globular structure of traps, . on ponza islands, . on trachyte, basalt, and tuff, . . sea cliffs, inland, . section of wealden, . section of white chalk from england to france, . section of volcanic rocks, auvergne, . sedgwick, prof., cited, . . on brecciated limestone, . on concretionary magnesian limestone, . on devonian group, . on garnets in altered rock, . on granite, . . on permian sandstones, . on joints and cleavage, . . on mineral composition of granite, . on old red of devon and cornwall, . on structure of rocks, . on trap rocks of cumberland, . segregation in mineral veins, . semi-opal, infusoria in, . serpulæ, on volcanic rocks, in sicily, . sewâlik hills, freshwater deposits, . shale, carbonaceous, . defined, . shales of coal near dudley, . sharpe, mr. d., on mollusca in silurian strata, . on slaty cleavage, . shells, fossil, in purbeck, . fossil, useful in classification, . in canada drift, . recent, in valley of niagara, . species of, near lisbon, . sheppey, isle of, fossil flora of, . sherringham, mass of chalk in drift, . shetland, granite of, . . hornblende schist of, . shrewsbury, coal deposit near, . sicily, fiume salso in, . inland cliffs in, . newer pliocene strata of, . terraces of denudation in, . sidlaw hills, trap of old red sandstone, . siebengebirge, igneous rocks of, . sienna, formations at, . sigillaria, . . siliceous limestone defined, . rocks defined, . silliman, prof., cited, . silurian, name explained, . period, plutonic rocks of, . rocks, table of, . strata, mineral character of, . strata of united states, . strata, thickness of, . strata, reptile in, postscript, vii. volcanic rocks, . simpson, mr., on ice islands, . sivatherium described, . skaptar jokul, eruption of, . skye, rocks of, . . basaltic columns in, . dikes in isle of, . sandstone in, . slaty cleavage, . slickensides, term defined, . smith, mr., of jordan hill, on pleistocene, . on shells near lisbon, . snags, fossil, . snakes' eggs, fossil at tonna near gotha, . solenhofen, lithographic stone of, . solfatara, decomposition of rocks in the, . somma, . lava at, . sopwith, mr. t., models by, . sortino, cave in valley of, . south devon and cornwall, old red of, . south downs, view of, . sowerby, mr. g., cited, . spatangus, figure of, . spezia, gulf of, calcareous rocks in, . spitzbergen, glaciers of, . sponges, figures of, in chalk, . spongilla of lamarck, in tripoli, . springs, mineral. see mineral springs, . staffa, basaltic columns in, . steno on classification of rocks, . stigmaria, . . in fossil forest, nova scotia, . stirling castle, rock of, altered by dike, . stokes, mr., on petrifaction, . stonesfield slate, . stonesfield, fossil mammalia, . and postscript, xviii. storton hill, footprints at, . strata, term defined, . arrangement of, determined by fossils, . . consolidation of, . curved and vertical, . . elevation of, above the sea, . fossiliferous, tabular view of, . horizontality of, . . metamorphic origin of, . mineral composition of, . outcrop of, . tertiary classification of, . stratification, forms of, . . . unconformable, . strickland, mr., on new red sandstone, . strike, term explained, . stromboli, lava of, . studer, m., on swiss alps, . on boulders of jura, . stutchbury, mr., cited, . subapennine strata, . . subsidence in drift period, . suffolk crag, . sullivan, capt., chart of falkland islands, . superior, lake, marl in, . superposition of aqueous deposits, . of volcanic rocks, test of age, . supracretaceous, term explained, . sussex marble, . swansea, coal measures near, . valley stems of _sigillaria_, . sydney coal field, cape breton, . syenite, . syenitic granite, . greenstone, . synclinal line, term defined, . t. table mountain, strata horizontal, . mountain, granite veins in, . talcose granite, . tartaret, puy de, cone of, . teeth of fossil mammalia, figures of, . teredina, fossil wood bored by, . teredo navalis boring wood, . terra del fuego, . _fucus giganteus_ in, . tertiary, term explained, . strata, tabular view of, . touraine, faluns of, . trachyte, . of hungary, . trachytic rocks, older than basalt, . transition, term explained, . trap, term explained, . dike in fifeshire, . globular structure of, . intrusion of, between strata, . various ages of, . . passage of granite into, . in radnorshire, . rocks, relation to lava, . rocks, lithological character of, . in lower eifel, . trappean rocks, . trap-tuff, . tertiary deposits, . . . texas, chalk in, . thames valley, freshwater deposits in, . thecodont saurians, . saurians, age of, postscript, xv. thirria, m., on oolitic group in france, . thurmann, m., cited, . . . _thuja occidentalis_ in stomach of mastodon, . till, term explained, . origin of, . tilestone, . tilgate forest, remains in, . tin, veins of, in cornwall, . . tiverton trap, porphyry near, . travertin, how deposited, . tree ferns in permian formation, . trias, or new red sandstone, . . and postsc., xiii. in cheshire and lancashire, . . trilobite in devonian strata, . trilobites of lower silurian, . trimmer, mr., on sand-galls, . on shells in drift near menai straits, . tripoli composed of infusoria, . tuff, volcanic, and trap, . . tuffs on wrekin and caer caradoc, . tuomey, mr., cited, . turner, dr., cited, . . tuscany, volcanic rocks of, . tynedale fault, . tynemouth cliff, limestone at, . u. uddevalla, shells of, compared with those near naples, . underlying, term applied to granite, . united states, coal field of, . cretaceous formation in, . devonian strata in, . eocene strata in, . older pliocene and miocene formations in, . oolite and lias of, . silurian strata of, . upsala, strata containing baltic shells near, . v. val di noto, composition of, . igneous rocks of, . inland cliffs in, . valleys, origin of, . transverse of weald, . valorsine granite, . veins, mineral. see mineral veins, . veinstones in parallel layers, . velay, volcanos of, . venetz, m., on alpine glaciers, . verneuil, m. de, on devonian flora, . on horizontal strata in russia, . on the old red sandstone in russia, . on _pentamerus knightii_, . on permian flora, . vesuvius, eruption of, . vicenza, basaltic columns near, . vidal, capt., survey by, . virginia, u. s., fossil shells in, . virlet, m., on corrosion of rocks by gases, . on geology of morea, . on inland cliffs, . volcanic mountains, form of, . . dikes, . volcanic rocks, age of, . described, . . analysis of minerals in, . cambrian, . composition and nomenclature, . of hungary, . post-pliocene period, . test of age of, . silurian, . volcanic tuff, . volcanos of auvergne, . extinct, . . . newer, of eifel, . in spain, age of, . round olot in catalonia, . von buch, baron, cited, . . . on boulders of jura, . on canary islands, . on cystideæ, . on land rising, . von dechen, m., on granite veins in cornwall, . oeynhausen, m., cited, . w. waller quoted, . warren, dr. j. c., on skeleton of _mastodon giganteus_, . waterhouse, mr., cited, . . on triassic mammifer, postscript, xiv. watt, mr. g., experiments on fused rocks, . . weald clay, . weald valley, denuded at what period, . wealden, term explained, . . the fracture and upheaval of, . extent of formation, . period, changes during, . wealden, plants and animals of, . . webster, mr. t., cited, . . . wellington valley, caves in, . wener lake, horizontal silurian strata of, . wenlock formation, . werner on classification of rocks, . on mineral veins, . on volcanic rocks, . westerwald, igneous rocks of, . westwood, mr., on beetles in lias, . whin-sill, intrusion of trap between strata, . white chalk, . white mountains, granite vein in, . wigham, mr., on fossils near norwich, . wolverhampton, fossil forest near, . wood, mr. searles, on fossils of crag, . on fossils of isle of wight, . on number of shells in crag, . on cetacea of crag, . cited, . . woodward, mr., on mammoth bones, norfolk, . wrekin, trap of, . wyman, dr., cited, . z. _zamia_, at lyme regis, . _zamia spiralis_, figure of, . zechstein, . _zeuglodon cetoides_, . and postscript, xxi. london: spottiswoodes and shaw, new-street-square. albemarle street, _july , _. mr. murray's =list of recent works= * * * * * history of the roman state; from - . by lugia carlo farini. translated from the italian by the right hon. w. e. gladstone, m.p. vols. vo. _s._ * * * * * the exposition of ; or, views of the industry, the science, and the government of england. by charles babbage, esq., author of the "economy of manufactures and machinery." _second edition_, with an appendix. vo. _s._ _d._ * * * * * the dovecote and the aviary; or, the natural history of pigeons and other domestic 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_the sermon may be had separately, price s._ * * * * * the evangelical and tractarian movements. by archdeacon wilberforce. (a charge delivered to and published by request of the clergy.) vo. _s._ * * * * * a history of erastianism. by archdeacon wilberforce. mo. _s._ * * * * * catholic safeguards against the errors, corruptions, and novelties of the church of rome. being discourses and tracts selected from the works of eminent divines of the church of england who lived during the th century; with preface, records, and a carefully compiled index. by rev. james brogden, m.a. vols. vo. _s._ * * * * * records of the supremacy of the crown, and the civil and religious liberties of the people of england. by rev. james brogden. vo. _s._ * * * * * horÆ ÆgyptiacÆ; or, the chronology of ancient egypt. discovered from astronomical and hieroglyphic records upon its monuments including many dates found in coeval inscriptions. by reginald stuart poole, esq. with plates. vo. _s._ _d._ "the substance of mr. poole's valuable work appeared originally in a series of papers in this journal. since their publication the author has devoted further time and attention to the subject; and it may safely be asserted that in their present amended and enlarged form, they are among the most important contributions that have yet been made to the study of egyptian chronology and history. we are indebted for the publication of the present valuable work to the liberality of the duke of northumberland, whose warm and generous support of literature and art deserves our grateful acknowledgments." _literary gazette._ * * * * * lavengro; the scholar--the gipsy--and the priest. by george borrow, esq. author of "the bible in spain," "the gipsies of spain," &c. &c. with a portrait. vols. post vo. _s._ "we trust our extracts have exhibited enough of one at least of the many aspects of 'lavengro' to convince the reader that neither is it a work to be read cursorily, nor to be handled easily, by any of the silver-fork school of critics. these volumes are indeed replete with life, with earnest sympathy for all genuine workers, with profound insight into the wants and wishes of the poor and uneducated, and a lofty disdain of the conventional 'shams' and pretensions which fetter the spirits or impede the energies of mankind. nor is a feeling for the beautiful less conspicuous in its pages. a quiet market-town, environed by green meadows or bosomed in tufted trees; an old mercantile and ecclesiastical city, with a history stretching from the times of the cæsars to the times of george iii.; the treeless plain, the broad river, the holt, the dingle, the blacksmith's forge, are all in their turn sketched freely and vividly by mr. borrow's pencil. in his portraitures of ruder life he is unsurpassed; a dog-fight, a prize-fight, an ale-house kitchen, greenwich fair, a savage group of wandering tinkers, are delineated in words as wilkie or hogarth might have depicted them in colours. we are embarrassed by the riches spread before us. "we have not touched upon the gipsy scenes in 'lavengro' because in any work of mr. borrow's these will naturally be the first to draw the reader's attention. neither have we aimed at abridging or forestalling any portions of a book which has a panoramic unity of its own, and of which scarcely a page is without its proper interest. if we have succeeded in persuading our readers to regard mr. borrow as partly an historian and partly as a poet, as well as to look for more in his volumes than mere excitement or amusement, our purpose is attained, and we may securely commend him to the goodly company he will find therein. 'lavengro,' however, is not concluded; a fourth volume will explain and gather up much of what is now somewhat obscure and fragmentary, and impart a more definite character to the philological and physiological hints comprised in those now before us. enough, indeed, and more than enough, is written to prove that the author possesses, in no ordinary measure, 'the vision and the faculty divine' for discerning and discriminating what is noble in man and what is beautiful in nature. we trust mr. borrow will speedily bring forth the remaining acts of his 'dream of adventure,' and with good heart and hope pursue his way rejoicing, regardless of the misconceptions or misrepresentations of critics who judge through a mist of conventionalities, and who themselves, whether travelled or untravelled, have not, like lavengro, grappled with the deeper thoughts and veracities of human life."--_tait's magazine._ * * * * * england in the nineteenth century: political, social, and industrial. by william johnston, esq. vols. post vo. _s._ "this book is a somewhat undigested mass of valuable matter, interspersed occasionally with reflections of much interest and observations of considerable originality. the author is unquestionably a man of talent; he writes with vigour and smartness; he has taken pains in the collection of most of his materials; and his statistics are arranged with great care and managed with unusual skill. in this point he is much superior to his prototype and apparent master, mr. alison." "mr. johnston's work is readable and well-written, abounding with information of many kinds."--_edinburgh review._ * * * * * the saxon in ireland: being notes of the rambles of an englishman in the west of ireland in search of a settlement. with map. post vo. _s._ _d._ "a valuable testimony to the capabilities of ireland."--_observer._ "let the intending emigrant devote a few hours to the perusal of this volume. the work possesses deeper interest than even could be claimed for it from its fascinating descriptions."--_illustrated news._ * * * * * sleep and dreams: two lectures delivered at the bristol literary and philosophical institution. by john addington symonds, m.d., consulting physician to the bristol general hospital. vo. _s._ _d._ * * * * * the palaces of nineveh and persepolis restored. an essay on ancient assyrian and persian architecture. by james fergusson esq., with woodcuts. vo. _s._ "this book contains many things of general interest relating to one of the most wonderful discoveries that has occurred in the history of the world. mr. fergusson writes very dispassionately. what he has said deserves serious consideration."--_gentleman's magazine._ * * * * * shall we keep the crystal palace and have riding and walking in all weathers, among flowers, sculpture, and fountains? by denarius. vo. _d._ * * * * * memoirs of robert plumer ward. with his correspondence, diaries, and literary remains. by the hon. edmund phipps. with portrait. vols. vo. _s._ "the most valuable portions of mr. ward's diary are its illustrations of the character of the duke of wellington. the great soldier, then in the flush of his military triumph, was also in the prime of his power and activity; and mr. ward gives us an insight into his business habits, his method of arguing public questions, his ready resource and never-tiring energy, which possesses occasionally a striking interest."--_examiner._ * * * * * the military events in italy, - . translated from the german. by the right hon. the earl of ellesmere. with a map. post vo. _s._ "military history is, as the earl of ellesmere declares, a rare article in english literature; and, therefore, he thought that the most authentic extant narrative of the operations implied in the title page of the present book, written by an impartial swiss, would not be an unwelcome addition to the british library. his lordship has judged rightly; the work of which he has presented a version is a worthy labour, and the events to which it relates are of the last importance. it is written with judgment, and has been translated with care."--_morning chronicle._ * * * * * a transport voyage to the mauritius, by way of the cape of good hope and st. helena. by the author of "paddiana." post vo. _s._ _d._ "this book reminds us of one of those pleasant fellows, whom one sometimes meets with in company, who has an anecdote or a story ready à propos of everything, whose fund of amusing tales is inexhaustible, and who rattling on from one thing to another, will keep a whole table in a roar, or a whole drawing-room in high glee. even such is our author. he gossips on and on, telling now of one adventure, and then of another; his volume is a perfect chaos of racy reminiscences graphically told."--_john bull._ * * * * * admiralty manual of scientific enquiry for the use of officers and travellers in general. by professors whewell, airy, owen, sir w. hooker, capt. beechey, j. r. hamilton, esq., sir john herschel, &c. edited by sir john f. herschel, bart. second edition. post vo. _s._ _d._ :: _published by authority of the lords commissioners of the admiralty._ * * * * * lives of the chief justices of england. from the norman conquest to the death of lord mansfield. by lord chief justice campbell. vols. vo. _s._ "there is, indeed, in lord campbell's works much instruction; his subjects have been so happily selected, that it was scarcely possible that there should not be. an eminent lawyer and statesman could not write the lives of great statesmen and lawyers without interweaving curious information, and suggesting valuable principles of judgment and useful practical maxims: but it is not for these that his works will be read. their principal merit is their easy animated flow of interesting narrative. no one possesses better than lord campbell the art of telling a story: of passing over what is commonplace; of merely suggesting what may be inferred; of explaining what is obscure; and of placing in strong light the details of what is interesting."--_edinburgh review._ * * * * * the forty-five. being a narrative of the rebellion in scotland of ; by lord mahon. post vo. _s._ "this is a very comprehensive and lively sketch of the famous 'rebellion' so vividly remembered, even after the lapse of a century, by the people of scotland. the incidents of that unfortunate invasion from first to last, from the landing of charles (july th) in borrodale, with the 'seven men of moidart,' to the fatal battle of culloden ( th april, ), are minutely and faithfully recorded; but we have no doubt the reader will be most and mainly interested in the personal history and adventures of the pretender himself. the character of the prince is admirably drawn, and generously vindicated from the calumnies heaped upon him by his adversaries after his fall. it will perhaps surprise some to learn, that he was so illiterate as scarcely to be master of the most common elements of education. 'his letters,' says lord mahon, 'which i have seen among the stuart papers, are written in a large, rude, rambling hand, like a schoolboy's. in spelling they are still more deficient.' we recommend lord mahon's narrative as a very agreeable sketch of a stirring and eventful period."--_edinburgh advertiser._ * * * * * a history of greece. from the earliest period to the end of the peloponnesian war. by george grote, esq. vols. i.-viii. with maps. vo. _s._ each. _the work may be obtained in portions, as it was published_:-- vols. i.-ii. legendary greece. grecian history to the reign of peisistratus at athens. vols. iii.-iv. history of early athens, and the legislation of solon. grecian colonies. view of the contemporary nations surrounding greece. grecian history down to the first persian invasion, and the battle of marathon. vols. v.-vi. persian war and invasion of greece by xerxes. period between the persian and the peloponnesian wars. peloponnesian war down to the expedition of the athenians against syracuse. vols. vii.-viii. the peace of nikias down to the battle of knidus [b.c. to .] socrates and the sophists. * * * * * kugler's handbook illustrated. the schools of painting in italy. from the earliest times. translated from the german by a lady, and edited with notes by sir charles lock eastlake, president of the royal academy. _a new edition._ vols. post vo. _s._ "we cannot leave this subject (_christian art, its present state and its prospects_), without reverting to sir c. eastlake's edition of kugler's handbook of painting, not for the sake of reviewing it,--for it is a work now of established reputation,--but for the purpose of recommending it as being upon the whole by far the best manual we are acquainted with, for every one who, without the opportunity of foreign and particularly italian travel, desires to make a real study of art. its method, its chronological arrangement, and its generally judicious criticism, make it most instructive to a learner. we may add that the present edition is enlarged just where the former one needed enlargement, and the handbook is now far more satisfactory as to the early religious schools than it was before. the edition is beautifully got up, and so profusely and judiciously illustrated by one hundred woodcuts drawn by scharf, that it would be next to impossible to speak too highly in its praise, even were its matter less valuable and important than it is."--_the ecclesiastic._ * * * * * christianity in ceylon: its introduction and progress under the portuguese, dutch, british, and american missions. by sir james emerson tennent, k.c.s., ll.d. with illustrations. vo. _s._ "to those who take either a religious or a philosophical interest in the subject, sir emerson tennent's volume may be safely recommended, as a clear, succinct, sensible, and flowing account. the work also possesses a living animation arising from the author's knowledge of the country and the people."--_spectator._ * * * * * the lexington papers. the courts of london and vienna in the th century. extracted from the private and official correspondence of lord lexington, while british minister at vienna, - . edited by the hon. h. manners sutton. vo. _s._ * * * * * the law and practice of naval courts-martial. by william hickman, r.n., late secretary to commodore sir charles hotham, k.c.b. vo. _s._ _d._ * * * * * a manual of elementary geology; or, the ancient changes of the earth and its inhabitants, as illustrated by its geological monuments. by sir charles lyell, f.r.s., p.g.s. third edition, thoroughly revised, and illustrated with woodcuts. vo. _s._ "the production of one of our most eminent geologists in an age of many. though styled a 'third edition,' it is in reality a new book. this could not be otherwise if the task were well done; for the science of which sir charles lyell treats is assuming new aspects every year. it is continually advancing and ever growing. as it advances, its steps become firmer and surer; as it grows, its framework becomes more compact, and its organization more perfect. they who take up the hammer to follow it must toil with unflagging tread to keep pace with its onward progress. if they lag behind, they can scarcely hope to overtake. none among its votaries has marked each movement more minutely, or weighed its value and purpose more judiciously, than the distinguished author of this manual. he has indeed done his task well, and both the beginner and the experienced investigator will find his book an invaluable guide and companion."--_literary gazette._ * * * * * commentaries on the war in russia and germany of - . by colonel the hon. george cathcart, deputy-lieutenant of the tower of london. with plans. vo. _s._ "as a treatise on the science of war, these commentaries ought to find their way into the hands of every soldier. in them is to be found an accurate record of events of which no military man should be ignorant."--_morning chronicle._ * * * * * modern domestic cookery. founded upon principles of economy and practical knowledge. and adapted for the use of private families. with woodcuts. post vo. _s._ "the advanced state of cookery having rendered mrs. rundell's work obsolete, the publisher has caused it to be remodelled and improved to such an extent as to give it a claim to the title of an original production. the receipts of the late miss emma roberts have been revised and added to the work; and it has had the advantage of being subjected besides to the careful inspection of a 'professional gentleman'--economy combined with excellence--is the aim, end, and object which it cannot be doubted will be obtained if its prescriptions are attended to. it is fuller than the former _domestic cookery_, of which it is an improved and amended edition--it is more simple and comprehensible in its language; it contains several diagrams not to be found in its predecessor; and it possesses various minor qualities, which increase its value in a tenfold degree, and make it, to say the least, equal to any other book of the kind in the english language."--_observer._ albemarle street, _july , _. mr. murray's =list of works in the press.= * * * * * selections from the despatches of the duke of wellington. by the late col. gurwood, c.b., k.c.t.s. a new edition. one volume. vo. * * * * * history of england, from the peace of utrecht. vols. & --the first years of the american war: -- . by lord mahon, m.p. vols. vo. * * * * * lives of the friends and contemporaries of lord chancellor clarendon. illustrative of portraits in his gallery; with an account of the origin of the collection; and a descriptive catalogue of the pictures. by lady theresa lewis. with portraits. vols. vo. * * * * * the treasures of art in great britain. being an account of the chief collections of paintings, sculpture, mss. miniatures, &c., &c., obtained from personal inspection during visits in and . (being a revised and greatly enlarged version of "art and artists in england.") by dr. waagen, director of the royal gallery of pictures at berlin. vols. vo. * * * * * the grenville papers; being the private correspondence of richard grenville, earl temple, k.g., and his brother, the right honourable george grenville, their friends and contemporaries, formerly preserved at stowe--now for the first time made public. _among the contents of this highly important accession to the history of great britain in the middle of the eighteenth century, will be found letters from_ h. m. king george the third. h. r. h. william duke of cumberland. dukes of:-- newcastle. devonshire. grafton. bedford. marquess:-- granby. earls:-- bute. temple. sandwich. egremont. halifax. hardwicke. chatham. mansfield. northington. suffolk. hillsborough. hertford. lords:-- lyttleton. camden. holland. clive. george sackville. ---- marshal conway. horace walpole (earl of orford). edmund burke. george grenville. john wilkes. william gerard hamilton. augustus hervey. mr. jenkinson (first earl of liverpool). mr. whately. mr. wedderburn (earl of roslyn). mr. charles yorke. mr. hans stanley. mr. charles townsend. mr. calcraft. mr. rigby. mr. knox. mr. charles lloyd. and the _author of the letters of junius_. including also, mr. grenville's diary of political events; particularly during the period of his administration as first lord of the treasury, from to . edited by william james smith, esq. vo. * * * * * personal narrative of an englishman domesticated in abyssinia. by mansfield parkyns, esq. with illustrations. vo. * * * * * lives of the three devereux, earls of essex, from to . . the earl marshall of ireland.-- . the favourite.-- . the general of the parliament. founded upon letters and documents chiefly unpublished. by the hon. captain devereux, r.n. vols. vo. * * * * * the present state of the republic of the rio de la plata (buenos ayres). its geography, resources, statistics, commerce, debt, etc., described. with the history of the conquest of the country by the spaniards. by sir woodbine parish, f.r.s., k.c.h, f.g.s., formerly her majesty's consul general and chargé d' affaires at buenos ayres. with new map and illustrations. vo. * * * * * contrasts of foreign and english society; or, records and recollections of a residence in various parts of the continent and england. by mrs. austin. vols. post vo. * * * * * the hand; its mechanism and endowments, as evincing design. by the late sir charles bell. _a new edition._ woodcuts. post vo. * * * * * naval and military technological dictionary. english and french.--french and english. for the use of soldiers, sailors, and engineers. by colonel burn, assistant inspector of artillery. small vo. * * * * * the life and reminiscences of thomas stothard, r.a. by mrs. bray. with numerous illustrations from his chief works, drawn on wood by g. scharf, jun., and printed in a novel and beautiful style. with a portrait. small to. * * * * * life and works of alexander pope. edited with notes. by the right hon. john wilson croker. portraits. vols. vo. * * * * * dictionary of greek and roman geography. by william smith, ll.d. with an historical atlas. vo. * * * * * a church dictionary. by walter farquhar hook, d.d., vicar of leeds. _sixth edition_, revised and enlarged. one volume. vo. "in this edition, besides the addition of many new articles, all those relating to important doctrinal and liturgical subjects have been enlarged. the authorities on which statements have been made, are given, with copious extracts from the works of our standard divines. special reference has been made to the romish controversy. attention has also been paid to the subjects of ecclesiastical and civil law, and to the statute law of england in church matters."--_extract from the preface._ * * * * * history of ancient pottery; egyptian, asiatic, greek, roman, etruscan, and celtic. by samuel birch, f.s.a. assistant keeper of the antiquities in the british museum. with illustrations. vo. uniform with "marryat's modern pottery and porcelain." * * * * * a sketch of madeira in . by edward vernon harcourt. a handbook for the use of travellers or invalids visiting the island. with a map and woodcuts. post vo. * * * * * the history of herodotus. a new english version. translated from the text of gaisford, and edited by rev. george rawlinson, m.a., exeter college, oxford. assisted by colonel rawlinson, c.b., and sir j. g. wilkinson, f.r.s., with copious notes and appendices, illustrating the history and geography of herodotus, from the most recent sources of information, embodying the chief results, historical and ethnographical, which have been arrived at in the progress of cuneiform and hieroglyphical discovery. vols. vo. the translation itself has been undertaken from a conviction of the entire inadequacy of any existing version to the wants of the time. the gross unfaithfulness of beloe, and the extreme unpleasantness of his style, render his translation completely insufficient in an age which dislikes affectation and requires accuracy; while the only other complete english versions which exist are at once too close to the original to be perused with any pleasure by the general reader, and also defective in respect of scholarship. * * * * * a treatise on naval gunnery, for the use of officers and for the training of seamen gunners. with descriptions of the guns introduced since the late war. by lieut.-gen. sir howard douglas, bart., g.c.b. _third edition_, revised. plates. vo. * * * * * considerations on steam warfare and naval shell-firing; by lieut.-gen. sir howard douglas, bart. vo. * * * * * letters and journals of general sir hudson lowe, revealing the true history of napoleon at st. helena. partly compiled and arranged by the late sir nicholas harris nicolas. with portrait. vols. vo. "from these papers the world will at last learn, as it ought long ago to have learnt, the _truth_, and the _whole truth_, respecting the captivity of napoleon."--_quarterly review._ * * * * * home sermons; or, sermons written for sunday reading in families. by rev. john penrose, m.a., vo. * * * * * history of greece for schools. on the plan of "mrs. markham's histories." with woodcuts. post vo. * * * * * state papers of henry the eighth's reign, comprising the correspondence between the english government and the continental powers, from the period of the election of charles v. to the death of henry viii. with indexes. vols. vi-xi. to. * * * * * the official handbook. being a manual of historical and political reference for all classes. one volume. fcap. vo. the design of this work is to show concisely the machinery by which the government of the country is carried on, giving such a succinct account of the duties, emoluments, and authorities of the various public departments, with their political relations, as will, it is hoped, render the volume a useful manual of reference to all strangers and foreigners desirous to make themselves acquainted with british institutions. * * * * * the british museum; handbook to the antiquities and sculpture there. by w. s. w. vaux, m.a., f.s.a., assistant in the department of antiquities in the british museum. with woodcuts. post vo. * * * * * handbook of chronology. alphabetically arranged to facilitate reference. one volume, vo. this work will enable the student or general reader, or man of the world, to put his finger at once upon the date of any particular event by means of a careful _alphabetical_ classified arrangement of the various elaborate chronologies which have been given to the world. it has been prepared with such care as will render it--it is hoped--a trustworthy book of reference. it contains the dates of the events which mark the rise, progress, decline, and fall of states; and the changes in the fortunes of nations. alliances, wars, battles, sieges, and treaties of peace; geographical discoveries, the settlement of colonies, and their subsequent story;--with all occurrences of general historic interest--are recorded in it. it further includes the years of the leading incidents in the lives of men eminent for worth, knowledge, rank, or fame; and of the writings, &c., &c., by which they are chiefly known; discoveries in every department of science; and inventions and improvements, mechanical, social, domestic, and economical. * * * * * handbook for syria and the holy land. with maps. post vo. * * * * * handbook for england and wales; giving an account of the places and objects best worth visiting in england, more especially those rendered interesting by historical associations, or likely to attract the notice of intelligent strangers and passing travellers; arranged in connexion with the most frequented roads and railways in england. showing, at the same time, the way of seeing them to the best advantage, with the least expenditure of time and money. _this work will appear in portions, as follows_:-- part i.--the eastern counties; including essex, suffolk, norfolk, cambridge, and lincoln. (_nearly ready._) part ii.--midland counties; herts, bedford, northampton, leicester, bucks, nottinghamshire. part iii.--derbyshire and yorkshire. part iv.--durham, northumberland, staffordshire, cheshire, lancashire, cumberland, the lakes. part v.--berks, bucks, oxfordshire, warwick, gloucester, worcester, hereford, shropshire, cheshire. part vi.--north and south wales. part vii.--devon and cornwall. (ready.) part viii.--somerset, wilts, dorset. part ix.--hampshire, isle of wight, sussex, surrey, kent. also, a condensed handbook of all england in one volume. with map and plans. post vo. * * * * * handbook of architecture. being a concise and popular account of the different styles prevailing in all ages and countries of the world. with a description of the most remarkable buildings. by james fergusson, esq., author of "indian architecture," "palaces of nineveh and persepolis restored." with very numerous illustrations on wood. vo. uniform with "kugler's handbook of painting." * * * * * handbook to the cathedrals of england. containing a short description of each. by the rev. g. a. poole, m.a., vicar of welford. with illustrative woodcuts. small vo. * * * * * handbook for the environs of london; with hints for excursions by rail--river--and road. by peter cunningham, f.s.a. post vo. * * * * * handbook of modern london; or, london as it is. giving full descriptions of all places and objects of interest in the metropolis and its vicinity. with a clue-map of london, plans, &c. mo. * * * * * a popular account of nineveh and its remains. by austen h. layard, d.c.l. abridged and condensed from his larger work. with numerous woodcuts. post vo. * * * * * bradbury and evans, printers, whitefriars. transcriber's notes: passages in italics are indicated by _underscore_. passages in fracture style are indicated by =fracture=. all greek has been transliterated and placed between +greek+. illustrations have been moved from the middle of a paragraph to the closest paragraph break. in the footnote -a (page ) lib. or liv. might be printed wrong. on page a footnote anchor was added to fig. -a. on page an potential anchor for footnote -a was guessed and added. on page an anchor for footnote -a was added. on page a footnote anchor -b was added. other than the corrections listed below, printer's inconsistencies in spelling, punctuation, hyphenation, and ligature usage have been retained. the use of capital letters in names, scientific classifications, locations, and time periods/eras is not consistent in this book, they have been kept as printed and only changed when an obvious error occurred. the system of abbreviations and punctuation in citations and figure captions can vary, the text has been kept as printed and only changed when an obvious error occurred. the punctuation in the index was inconsistent, all commas in listings for page numbers have been changed into full stops, they are not specially mentioned/marked in the list of changes. the alphabetic order in the index is sometimes inconsistent but has been kept as printed. palæomæryx (page ) is known in the literature by paleomeryx (http://www.paleodatabase.org) as well as palaeomeryx. palæoniscus is known in the literature as palaeoniscus. inoceramus cuvieri is today known as inoceramus cuvieri (ref: cretaceous fossils of north america). different spelling of ashby de la zouch (text) and ashby-de-la-zouch (index) was retained. older or unusual forms of spelling of some german and french towns and locations have been retained (e.g. bertrich-baden--bad bertrich, roderberg--rodderberg, gemunder maar--gemünder maar, boulade--boulaide, pont gibaud--pontgibaud, saarbrück--saarbrücken). the following words have been retained in both versions: agas. and agass. brachiopod, brachiopods and brachiopoda (as well as with capital letters or lower case) bunter sandstein and bunter-sandstein (as well as various combinations with bunter, bunter, sandstein, sandstein) cheirotherium and chirotherium as cheirotherian and chirotherian didelphis and didelphys dike/s and dyke/s foot-print/s and footprint/s foot-marks and footmarks gault and gault g/grauwacke and g/grauwacké and their english translations (greywacke) greensand and greensand as well as their variations holoptichius (e.g. lyell) and holoptychius (general usage) ichthyolites and icthyolites iron-stones and ironstones jaw-bone and jawbone keuper and keuper lias and lias liége and liege muschelkalk and muschelkalk non-fossiliferous and nonfossiliferous old red sandstone and old red sandstone with all variations p/palæo** and p/paleo** with all variations from paleontological to paleozoic pozzolana and pozzuolana (recent form) primæval and primeval quâquâversal and qua-quaversal rhinoceros tichorhinus and rhinoceros tichorinus scoria and scoriæ sénonien and senonien tilestone/s and t/tile-stone/s the following misprints have been corrected: changed "to recognise rocks" into "to recognize rocks" page vi changed "a fresh-water or" into "a freshwater or" page viii changed "belong to gasterodous" into "belong to gasteropodous" page x changed "ova in a carbonised state." into "ova in a carbonized state." page xi (fig. a) changed "würtembergisch. naturwissen jahreshefte" into "würtembergisch. naturwissen. jahreshefte" footnote xiii-a changed "by herman von meyer" into "by herman von meyer." page xiv (fig. ) changed "near stuttgart, wurtemberg." into "near stuttgart, würtemberg." page xiv changed "is characterised by" into "is characterized by" page xvi changed "genus sauricthys, hybodus," into "genus saurichthys, hybodus," page xv changed "sauricthys mougeotii, is" into "saurichthys mougeotii, is" page xv changed "in the quader sand-stein and" into "in the quadersandstein and" page xvi changed "of organisation in fossils" into "of organization in fossils" page xix changed "or to plerodactyles" into "or to pterodactyles" page xix changed "class aves have hither to" into "class aves have hitherto" page xix changed "bored by teredina" into "bored by teredina" page xxiii changed "near st. andrew's" into "near st. andrews" page xxix changed "sub-marine lava" and into "submarine lava and" page xxix changed "granite of dartmore altering" into "granite of dartmoor altering" page xxx changed "concluding remarks " into "concluding remarks " page xxxi changed "occasionally characterised" by into "occasionally characterized" by page changed "are all characterised" into "are all characterized" page changed "loire, and ardêche," into "loire, and ardèche," page changed "giants' causeway, called" into "giant's causeway, called" page changed "cooled and crystallised," into "cooled and crystallized," page changed "by dr. mac culloch" into "by dr. macculloch" page changed "afterwards super-imposed, and" into "afterwards superimposed, and" page changed "causes, while super-imposed" into "causes, while superimposed" page changed "(green-sand formation.)" into "(greensand formation.)" page changed "annexed fig. ( .)," into "annexed fig. .," page changed "(green-sand formation?)" into "(greensand formation?)" page changed "bored by teredina" into "bored by teredina" page changed "great bed of tripoli, bilin." into "great bed of tripoli, bilin." page (figs. / ) changed figure number figure " " into figure " " page changed "information from icthyolites" into "information from ichthyolites" page changed "confined to vein-stones." into "confined to veinstones." page changed "the drying and skrinking" into "the drying and shrinking" page changed "conglomerate, n. . clay," into" conglomerate, no. . clay," page changed "described by dr. macculloch," into "described by dr. macculloch," page changed "of ross-shire. (macculloch.)" into "of ross-shire. (macculloch.)" page (fig. ) changed "dax, near bourdeaux" into "dax, near bordeaux" page changed "indicate the intermittance" into "indicate the intermittence" page changed figure number " " to figure " " page changed "modica, precipitious" into "modica, precipitous" page changed "them by dr. macculloch," into "them by dr. macculloch," page changed "dr. macculloch and" into "dr. macculloch and" page changed "have ever re-appeared" into "have ever reappeared" page changed "fossilisation of certain" into "fossilization of certain" page changed "hills called bruder holz" into "hills called bruderholz" page changed "near stuttgardt, in" into "near stuttgart, in" page changed "stones have travelled" into "stones have travelled." page changed "already characterised by" into "already characterized by" page changed "neighbourhood of upsal," into "neighbourhood of upsala," page changed "isles of sub-aerial glaciers." into "isles of subaerial glaciers." page added "boulder formation--continued." to chapter heading page changed "its materials rearranged" into "its materials re-arranged" page changed "chapters and .," into "chapters . and .," page changed "to coexist in" into "to co-exist in" page changed "class of warm-blodded" into "class of warm-blooded" page changed "speces of deer" into "species of deer" page changed "skeletons of magatherium," into "skeletons of megatherium," page changed "student to recognise the" into "student to recognize the" page changed "b. nat. size of a and b." into "c. nat. size of a and b." page (fig. ) changed "overan are a" into "over an area" page changed "concretionary rearrangement of" into "concretionary re-arrangement of" page changed "faseicularia aurantium" into "fascicularia aurantium" page (fig. ) changed "v. exterior." into "a. exterior." page (fig. .) changed "climates, such a" into "climates, such as" page changed "clayslate, and various" into "clay-slate, and various" page changed "from the appenines" into "from the apennines" page changed " per cent," into " per cent.," page changed "beds (sables inferieurs" into "beds (sables inférieurs" page changed "inferieurs et argiles" into "inférieurs et argiles" page changed "upper marine or fontainbleau" into "upper marine or fontainebleau" page changed "m. de koninck of liége" into "m. de koninck of liége" page changed "or caddice-fly" into "or caddis-fly" page changed "lake of the lemagne" into "lake of the limagne" page changed "bagshot and brocklesham division" into "bagshot and bracklesham division" page changed "nome of them" into "none of them" page changed "genera emys and trionix." into "genera emys and trionyx." page changed "sables moyens. divide" into "sables moyens, divide" page changed "of the english eocenestrata," into "of the english eocene strata," page changed "headen hill, on" into "headon hill, on" page changed "egerton has recognised" into "egerton has recognized" page changed "brown and blueish gray" into "brown and blueish grey" page changed "beds nos. , . are" into "beds nos. , ., are" page changed "places for mill-stones." into "places for millstones." page changed "of d'orbigny before" into "of d'orbigny before" page changed "sea-cliffs at stevensklint" into "sea-cliffs at stevens klint" page changed "and ostrea, vesicularis." into "and ostrea vesicularis." page changed "bivalves (figs. . ," into "bivalves (figs. , ," page changed "the dammura of" into "the dammara of" page changed "afterwards recognised by" into "afterwards recognized by" page changed "of the radack achipelago," into "of the radack archipelago," page changed "observations of ferdinand roemer;" into "observations of ferdinand römer;" page changed "the marl-stones are" into "the marlstones are" page changed "wealden (see nos. " into "wealden (see nos. ." page changed "purely fresh-water origin." into "purely freshwater origin." page changed "auvergne (see above, p. .)" into "auvergne (see above, p. .)." page changed "genera trioynx and emys," into "genera trionyx and emys," page changed "see flinder's voyage." into "see flinders' voyage." footnote -a changed "author's annivers. address," into "author's anniv. address," footnote -c changed "those from the gualt" into "those from the gault" page changed "eological map of" into "geological map of" page (fig. ) changed "(fig. .), where" into "(fig. .), where" page changed "in the north" into "in the north" page changed "in the wood-cut" into "in the woodcut" page changed "south downs at beachy head." into "south downs at beachy head." page changed "fail to recognise in" into "fail to recognize in" page changed "voll. ii. p. ." into "vol. ii. p. ." footnote -a changed "of clay aud limestone," into "of clay and limestone," page changed "coral rag," into "coral rag." page (fig. ) changed "in their orginal" into "in their original" page changed "says mr lycett," into "says mr. lycett," page changed "such as pleiosaur," into "such as plesiosaur," page changed "obtained by dr buckland" into "obtained by dr. buckland" page changed "that the thuia," into "that the thuja," page changed "buckland's bridgw. treat." into "buckland's bridgew. treat." page (fig. ) changed "lower shales are wel" into "lower shales are well" page changed "the oolitic system generally" into "the oolitic system generally." page changed " / nat size." into " / nat. size." page (fig. ) changed "(g. arcuata, lam)" into "(g. arcuata, lam.)" page (fig. ) changed "their own predacious race" into "their own predaceous race" page changed "both of icthyosaur and plesiosaur" into "both of ichthyosaur and plesiosaur" page changed "for swimming (see fig. .)" into "for swimming (see fig. .)." page changed "sir h. de la beche," into "sir h. de la beche," page changed "of the haute saône," into "of the haute-saône," page changed "in germany-keupar" into "in germany-keuper" page changed "buckland, bridg. treat.," into "buckland, bridgew. treat.," footnote -a changed calcaire coquillier into "calcaire coquillier." page changed "württemberg, and is" into "würtemberg, and is" page changed "genera sauricthys and gyrolepis" into "genera saurichthys and gyrolepis" page changed "near strazburg, on" into "near strasburg, on" page changed "the "gres bigarré," or" into "the "grès bigarré," or" page changed "vol. v. p. " into "vol. v. p. ." footnote -b changed "in the gray, and" into "in the grey, and" page changed "with ornithicnites on" into "with ornithichnites on" page changed "and botroidal character." into "and botryoidal character." page changed "the icthyolites which" into "the ichthyolites which" page changed "pygopteris mandibularis" into "pygopterus mandibularis" page (fig. ) changed "gutbier are asterophillites" into "gutbier are asterophyllites" page changed "lepidodendra, calamites, asterophillites," into "lepidodendra, calamites, asterophyllites," page changed "same bands of" into "some bands of" page changed "sometimes called fire-stone," into "sometimes called firestone," page changed "geol. soc proceedings," into "geol. soc. proceedings," footnote -b changed "f. . feet oal" into "f. . feet coal." page (fig. ) changed "at an angle of °," into "at an angle of °." page changed "genus called michroconchus" into "genus called microconchus" page changed "of sigillaria, lepidodrendon," into "of sigillaria, lepidodendron," page changed "frequently recognised. thus," into "frequently recognized. thus," page changed "be recognised at still" into "be recognized at still" page changed "clay iron-stone.--bands and nodules of clay iron-stone" into "clay-iron-stone.--bands and nodules of clay-iron-stone" page changed dome-shaped out-crop of into dome-shaped outcrop of page changed "ornithichnites (see p. .)." into "ornithichnites (see p. .)." page changed "the out-crop of" into "the outcrop of" page changed "olifiant gas. the" into "olefiant gas. the" page changed "american journ. of sci," into "american journ. of sci.," footnote -a changed "a neucleus of granite," into "a nucleus of granite," page changed "scale of holoptychus nobilissimus," into "scale of holoptychius nobilissimus," page (fig. ) changed "peculiar lamelli-branchiate" into "peculiar lamellibranchiate" page changed "south from st. petersburgh." into "south from st. petersburg." page changed "of the astræa." into "of the astrea." page changed "lowest or mud-stone beds," into "lowest or mudstone beds," page changed "showing siphuncle. ludlow" into "showing siphuncle. ludlow." page (fig. ) changed "the welch mountains afford." into "the welsh mountains afford." page changed "kleyn spawen beds," into "kleyn spauwen beds," page changed "belong to neighboring" into "belong to neighbouring" page changed "with gypsum--wirtemberg," into "with gypsum--würtemberg," page changed "crinoidians abundant" into "crinoideans abundant" page changed "like chelonians, ptericthys," into "like chelonians, pterichthys," page changed "were recognised as" into "were recognized as" page changed "their igneons origin" into "their igneous origin" page changed "recognised by a peculiar" into "recognized by a peculiar" page changed "one half i scoriaceous," into "one half is scoriaceous," page changed "others are andesitic," into "others are andesitic," page changed "tom. . p. . ." into "tom. . p. . .)" page changed "a green porphyritic rocks" into "a green porphyritic rock" page changed "saussurite, a mineral" into "saussurite, a mineral" page changed "oxyde of iron." into "oxide of iron." page changed "of talc. burat's" into "of talc. (burat's" page changed "sub-marine lava and" into "submarine lava and" page changes "much as per cent of" into "much as per cent. of" page changed "of hutt. theory, s. ." into "of hutt. theory, p. ." footnote -b changed "giants' causeway, in ireland." into "giant's causeway, in ireland." page changed "bottom of a shallow sea" into "bottom of a shallow sea." page changed "to larva and" into "to lava and" page changed "porm, structure, and" into "form, structure, and" page changed "baranco de las angustias." into "barranco de las angustias." page changed "lie uncomformably to" into "lie unconformably to" page changed "trap-dikes of etna," into "trap dikes of etna," page changed "the accompanying wood-cut" into "the accompanying woodcut" page changed "in once instance" into "in one instance" page changed "punto del nasone on somma" into "punta del nasone on somma" page (fig. ) changed "we recognise the ordinary" into "we recognize the ordinary" page changed "near st. andrew's" into "near st. andrews" page changed "crystals of mesotyge" into "crystals of mesotype" page changed "h. de la beche during" into "h. de la beche during" page changed "geol. trans, d" into "geol. trans., d" footnote -e changed "silex, thay have" into "silex, they have" page changed "except when mineralogicaly" into "except when mineralogically" page changed "bontigny's experiments have" into "boutigny's experiments have" page changed "mineral camposition-test" into "mineral composition-test" page changed "granite of dartmore altering" into "granite of dartmoor altering" page changed "are many vareties" into "are many varieties" page changed "the gritz quartzose" into "the grits quartzose" page changed "ay at smome" into "may at some" page changed "and their synonymes." into "and their synonymies." page changed "these aeriform fluids," into "these aëriform fluids," page changed "fumeroles have been" into "fumaroles have been" page changed "its being nonfossiliferous," into "its being non-fossiliferous," page changed "have become matamorphic" into "have become metamorphic" page changed "mm. studer, and hugi," into "mm. studer and hugi," page changed "hornblende-schist, chlorine-schist," into "hornblende-schist, chlorite-schist," page changed "enlarged or reopened." into "enlarged or re-opened." page changed "vein of andreasburg" into "vein of andreasberg" page changed "greenstone, or "toad-stone,"" into "greenstone, or "toadstone,"" page changed "can be recognised in" into "can be recognized in" page changed "h. de la beche during" into "h. de la beche during" page changed "lithodomi in beaches" into "lithodomi in beaches," page changed "barrarde, m., on trilobites, ." into "barrande, m., on trilobites, ." page changed "argile plastiqne, or" into "argile plastique, or" page changed "or inland" into "on inland" page changed "on cornish lodes," into "on cornish lodes," page changed "on sewalik hills," into "on sewâlik hills," page changed "caryophillia cespitosa, bed" into "caryophyllia cæspitosa, bed" page changed "cystidiæ in silurian rocks, ." into "cystideæ in silurian rocks, ." page changed "decken, prof. von, on reptiles in saarbrück coalfield, ." into "dechen, prof. von, on reptiles in saarbrück coal-field, ." page changed "france, - ." into "france, - ." page changed "doué, m. b. de, on" into "doue, m. b. de, on" page changed "desroyers, m., on" into "desnoyers, m., on" page changed "on icthyosaurus, ." into "on ichthyosaurus, ." page changed "hill of gergovla," into "hill of gergovia," page changed "on cystidiæ, ." into "on cystideæ, ." page changed "glenroy, parallel" into "glen roy, parallel" page changed "sienitic, ." into "syenitic, ." page changed "vesiculosus in lym-fiord, ." into "vesiculosus in lym-fiord, ." page changed "hamilton. sir w.," into "hamilton, sir w.," page changed "hooghley river, analysis" into "hooghly river, analysis" page changed "icthyolites of old" into "ichthyolites of old" page changed "icthyosaurus communis, figure" into "ichthyosaurus communis, figure" page changed "period, volcanic rocks," into "period. volcanic rocks," page changed "kentish chalk, sandgalls" into "kentish chalk, sand-galls" page changed "limestone, fosslliferous," into "limestone, fossiliferous," page changed "lochabar, parallel roads" into "lochaber, parallel roads" page changed "in cannel coal" into "in cannel coal" page changed "enlarged and reopened, ." into "enlarged and re-opened, ." page changed "teeth of. figured," into "teeth of, figured," page changed "mammifer in trlas" into "mammifer in trias" page changed "on stonefield slate, ." into "on stonesfield slate, ." page changed "mososaurus in st. peter's" into "mosasaurus in st. peter's" page changed "oeynhansen, m. von, on" into "oeynhausen, m. von, on" page changed "saarbruck coal field," into "saarbrück coal field," page changed "sandpipes near," into "sand-pipes near," page changed "st. andrew's, trap" into "st. andrews, trap" page changed "plutonic rocks, - ." into "plutonic rocks, . ." page changed "rose, frof. g.," into "rose, prof. g.," page changed "of colebrook dale," into "of coalbrook dale," page changed "sandpipes in, ." into "sand-pipes in, ." page changed "sandpipes near maestricht" into "sand-pipes near maestricht" page changed "or sandgalls, term" into "or sand-galls, term" page changed "seacliffs, inland, ." into "sea cliffs, inland, ." page changed "sedgewick, prof., cited," into "sedgwick, prof., cited," page changed "sedgewick, prof., on" into "sedgwick, prof., on" page changed "sewalik hills, freshwater" into "sewâlik hills, freshwater" page changed "skapter jokul, eruption" into "skaptar jokul, eruption" page changed "sub-apennine strata, . ." into "subapennine strata, , ." page changed "on sand galls, ." into "on sand-galls, ." page added header "w." in index page changed "wenlok formation, ." into "wenlock formation, ." page changed "whin-sil, intrusion of" into "whin-sill, intrusion of" page changed "on cystidæ, ." into "on cystideæ, ." page changed "in 'lavengro.' because" into "in 'lavengro' because" advertisements changed "vols. i-viii. with" into "vols. i.-viii. with" advertiesements changed "early religous schools" into "early religious schools" advertisements changed "its organisation more" into "its organization more" advertisements changed "with unfagging tread" into "with unflagging tread" advertisements changed "of time and money" into "of time and money." advertisements changed "a condensed hand-book of all england" into "a condensed handbook of all england" advertisements changed "leicester, bucks nottinghamshire." into "leicester, bucks, nottinghamshire." advertisements changed "warwick, glocester, worcester," into "warwick, gloucester, worcester," advertisements transcriber's note italic text is denoted by _underscores_ and bold text by =equal signs=. whole and partial numbers are displayed as - / . [illustration: photo, ridge studio; courtesy ogden chamber of commerce] _a great ledge in ogden canyon near ogden, utah. the rock, still retaining its stratification, was deposited layer upon layer horizontally mostly as sand upon the floor of a sea which covered the region fully , , years ago. that the sea was of very early paleozoic (i.e., cambrian) age has been proved by fossils in associated strata. long after their deep burial and consolidation within the earth, the strata were subjected to tremendous mountain-making pressure, notably altered to a rock called "quartzite," raised high above sea level, and tilted almost vertically. then through long ages (millions of years) overlying rocks of great thickness have been cut away (eroded) by weathering and stream action, laying bare the ledge as we see it to-day._ popular science library editor-in-chief garrett p. serviss authors william j. miller hippolyte gruener a. russell bond d. w. hering loomis havemeyer ernest g. martin arthur selwyn-brown robert chenault givler ernest ingersoll wilfred mason barton william b. scott ernest j. streubel norman taylor david todd charles fitzhugh talman robin beach arranged in sixteen volumes with a history of science, glossaries and a general index _illustrated_ [illustration] volume three p. f. collier & son company new york copyright by p. f. collier & son company manufactured in u. s. a. geology the science of the earth's crust by william j. miller professor of geology, smith college [illustration] p. f. collier & son company new york preface in the preparation of this book the author has attempted to present, in popular form, the salient points of a general survey of the whole great science of geology, the science which deals with the history of the earth and its inhabitants as revealed in the rocks. the use of technical and unusual terms has been reduced to a minimum compatible with a reasonable understanding of the subject by the layman. each of the relatively few scientific terms is explained where first used in the text, and a glossary of common geological terms has been appended. the matter of illustrations has received very careful attention, and only pictures, maps, and diagrams are used which actually illustrate important features of the text. a special point has been made to introduce only cuts of simple construction comparatively free from technicalities. nearly every illustration is accompanied by a really explanatory title. a number of the pictures are from the author's collection of photographs, and many of the line-cuts have either been made or considerably modified by the author. among the numerous sources of illustrations, special mention should be made of the united states geological survey, the new york state museum, the american museum of natural history, the university of chicago press, and various individuals, full credit being given wherever due. william j. miller. northampton, mass. contents chapter page i. introduction ii. weathering and erosion iii. stream work iv. the sea and its work v. glaciers and their work vi. the action of wind vii. instability of the earth's crust viii. volcanoes and igneous rocks ix. waters within the earth x. how mountains come and go xi. a study of lakes xii. how the earth may have originated xiii. very ancient earth history xiv. ancient earth history xv. medieval earth history xvi. modern earth history xvii. evolution of plants xviii. geological history of animals (excluding vertebrates) xix. geological history of vertebrate animals (including man) xx. mineralogy xxi. economic geology glossary of common geological terms list of illustrations ledge of rock with nearly vertical strata _frontispiece_ plate facing page granite weathering to soil leaving residual cores of joint blocks (_upper picture_) looking-glass rock, utah. stratified sandstone sculptured by wind erosion (_lower picture_) grand canyon of the yellowstone river. a channel worn by erosion gorge of the niagara river below the falls. a sample of recent erosion winding stream in the st. lawrence valley with flood plain (_upper picture_) davidson glacier, alaska, showing action on the valley's walls and floor (_lower picture_) swift current valley in glacier national park, formed by stream and glacier action yosemite valley from western entrance. the result of glacial action an upbend fold or anticline in maryland ledge of igneous rock showing joints (_upper picture_) fault fracture in limestone formations (_lower pictures_) molten lava flowing over a cliff in hawaii (_upper picture_) dikes of granite cutting old rock (_lower picture_) lassen peak, california, in eruption (_left picture_) devil's tower, wyoming, once a mass of molten rock forced through strata (_right picture_) mammoth hot springs terrace in yellowstone national park (_upper picture_) crater lake, oregon, formed by the subsidence of a volcano (_lower picture_) archeozoic rock, oldest known rock formation on earth (_upper picture_) twisted mass of stratified limestone, surrounded by granite (_lower picture_) paleozoic rock, covered with oldest known animal remains "stone-lily" stems in ordovician strata (_upper left picture_) various brachiopods in ordovician strata (_upper right picture_) stratified limestone of middle ordovician era containing fossils (_lower picture_) a landscape of the coal age (_upper picture_) fossil fern on a piece of shale (_lower picture_) restoration of huge animals of the mesozoic era skeleton of two-legged carnivorous dinosaur (_large picture_) earliest known bird form (_insert_) skeleton of large flying reptile (_upper picture_) skeleton of a swimming reptile of the mesozoic era (_lower picture_) appalachians along new river, peneplain upraised again glacial bowlder left by ice sheet (_upper picture_) esker, deposited by a stream in the great glacier (_lower picture_) chapter i introduction earth features are not fixed. the person of ordinary intelligence, surrounded as he is by a great variety of physical features, is, unless he has devoted some study to the subject, very likely to regard those features as practically unchangeable, and to think that they are now essentially as they were in the beginning of the earth's history. some of the most fundamental ideas taught in this book are that the physical features of the earth, as we behold them to-day, represent but a single phase of a very long-continued history; that significant changes are now going on all around us; and that we are able to interpret present-day earth features only by an understanding of earth changes in the past. _geology_, meaning literally "earth science," deals with the history of the earth and its inhabitants as revealed in the rocks. the science is very broad in its scope. it treats of the processes by which the earth has been, and is now being, changed; the structure of the earth; the stages through which it has passed; and the evolution of the organisms which have lived upon it. _geography_ deals with the distribution of the earth's physical features, in their relation to one another, to the life of sea and land, and human life and culture. it is the present and outward expression of geological effects. as a result of the work of many able students of geology during the past century and a quarter, it is now well established that our planet has a definitely recorded history of many millions of years, and that during the lapse of those eons, revolutionary changes in earth features have occurred, and also that there has been a vast succession of living things which, from very early times, have gradually passed from simple into more and more complex forms. the physical changes and the organisms of past ages have left abundant evidence of their character, and the study of the rock formations has shown that within them we have a fairly complete record of the earth's history. although very much yet remains to be learned about this old earth, it is a remarkable fact that man, through the exercise of his highest faculty, has come to know so much concerning it. the following words, by the late professor barrell, admirably summarize the significance of geological history. "the great lesson taught by the study of the outer crust is that the earth mother, like her children, has attained her present form through ceaseless change, which marks the pulse of life and which shall cease only when her internal forces slumber and the cloudy air and surf-bound ocean no more are moving garments. the flowing landscapes of geologic time may be likened to a kinetoscopic panorama. the scenes transform from age to age, as from act to act; seas and plains and mountains of different types follow and replace each other through time, as the traveler sees them succeed each other in space. at times the drama hastens, and unusual rapidity of geologic action has, in fact, marked those epochs since man has been a spectator upon the earth. science demonstrates that mountains are transitory forms, but the eye of man through all his lifetime sees no change, and his reason is appalled at the conception of a duration so vast that the milleniums of written history have not accomplished the shifting of even one of the fleeting views which blend into the moving picture."[a] [a] central connecticut in the geologic past, pp. - . or in the words of tennyson: there rolls the deep where grew the tree. o, earth, what changes hast thou seen! there where the long street roars, hath been the stillness of the central sea. the hills are shadows, and they flow from form to form, and nothing stands; they melt like mist, the solid lands, like clouds they shape themselves and go. the following statement of some of the more definite important conclusions regarding earth changes may serve to make still clearer the general scope of the science of geology. the evidences upon which these conclusions are based are discussed in various parts of this book. for untold millions of years the rocks at and near the earth's surface have been crumbling; streams have been incessantly sawing into the lands; the sea has been eating into continental masses; the winds have been sculpturing desert lands; and, more intermittently and locally, glaciers have plowed through mountain valleys, and even great sheets of ice have spread over considerable portions of continents. throughout geologic time, the crust of the earth has shown marked instability. slow upward and downward movements of the lands relative to sea level have been very common, in many cases amounting to even thousands of feet. various parts of the earth have been notably affected by sudden movements (resulting in earthquakes) along fractures in the outer crust. during millions of years molten materials have, at various times, been forced into the earth's crust, and in many cases to its surface. mountain ranges have been brought forth and cut down. the site of the appalachian mountains was, millions of years ago, the bottom of a shallow sea. lakes have come and gone. the great lakes have come into existence very recently (geologically), that is to say, since the great ice age. a study of stratified rocks of marine origin shows that all, or nearly all, of the earth's surface has at some time, or times, been covered by sea water. over certain districts the sea has transgressed and retrogressed repeatedly. organisms have inhabited the earth for many millions of years. in earlier known geologic time, the plants and animals were comparatively simple and low in the scale of organization, and through the succeeding ages higher and more complex types were gradually evolved until the highly organized forms of the present time, including the human race, were produced. the rocks of the earth constitute the special field of study for the geologist because they contain the records of events through which the earth and its inhabitants have passed during the millions of years of time until their present conditions have been reached. all the rocks of the earth's crust may be divided into three great classes: _igneous_, _sedimentary_, and _metamorphic_. _igneous_ rocks comprise all those which have ever been in a molten condition, and of these we have the _volcanic_ rocks (for example, lavas), which have cooled at or near the surface; _plutonic_ rocks (for example, granites), which have cooled in great masses at considerable depths below the surface; and the _dike_ rocks which, when molten, have been forced into fissures in the earth's crust and there cooled. _sedimentary_ rocks comprise all those which have been deposited under water, except some wind-blown deposits, and they are nearly always arranged in layers (stratified). such rocks are called strata. they may be of mechanical origin such as clay or mud which hardens to _shale_; sand, which consolidates into _sandstone_; and gravel, which when cemented becomes _conglomerate_. they may be of organic origin such as limestone, most of which is formed by the accumulation of calcareous shells; _flint_ and _chert_, which are accumulations of siliceous shells; or _coal_, which is formed by the accumulation of partly decayed organic matter. or, finally, they may be formed by chemical precipitation, as beds of _salt_, _gypsum_, _bog iron ore_, etc. _metamorphic_ rocks include both sedimentary and igneous rocks which have been notably changed from their original condition. traces or remains of plants and animals preserved in the rocks are known as fossils. the term originally meant anything dug out of the earth, whether organic or inorganic, but for many years it has been strictly applied to organic remains. many thousands of species of fossils are known from rocks of all ages except the oldest, and more are constantly being brought to light, but these represent only a small part of the life of past ages because relatively few organic remains were deposited under conditions favorable for preservation in fossil form. the fossils in the rocks are, however, a fair average of the groups of organisms to which they belong. it is really remarkable that such a vast number of fossils are imbedded in the rocks, and from a study of these many fundamental conclusions regarding the history of life on our planet may be drawn. as early as the fifth century b. c., xenophanes is said to have observed fossil shells and plants in the rocks of paros, and to have attributed their presence to incursions of the sea over the land. herodotus, about a century later, came to a similar conclusion regarding fossil shells in the mountains of egypt. none of the ancients, however, seemed to have the slightest conception of the significance of fossils as time markers in the history of the earth. (see discussion below.) in the middle ages, distinguished writers held curious views regarding fossils. thus avicenna ( - ) believed that fossils represented unsuccessful attempts on the part of nature to change inorganic materials into organisms within the earth by a peculiar creative force (_vis plastica_). about two centuries later, albertus magnus held a somewhat similar view. leonardo da vinci ( - ), the famous artist, architect, and engineer, while engaged in canal building in northern italy, saw fossils imbedded in the rocks, and concluded that these were the remains of organisms which actually lived in sea water which spread over the region. during the seventeenth and eighteenth centuries, many correctly held that fossils were really of organic origin, but it was commonly taught that all fossils represented remains of organisms of an earlier creation which were buried in the rocks during the great deluge (noah's flood). william smith ( - ), of england, was, however, the first to recognize the fundamental significance of fossils for determining the relative ages of sedimentary rocks. this discovery laid the foundation for the determination of earth chronology which is of great importance in the study of the history of the earth. (see discussions below.) organic remains, dating as far back as tens of millions of years, have been preserved in the rocks of the earth in various ways. a very common kind of fossilization is the preservation of only the hard parts of organisms. thus the soft parts have disappeared by decomposition, while the hard parts, such as bones, shells, etc., remain. in many cases practically complete skeletons of large and small animals which lived millions of years ago have been found intact in the rocks. fossils which show none of the original material, but only the shape or form, are also very abundant. when sediment hardens around an imbedded organism, and the organism then decomposes or dissolves away, a cavity or fossil mold only is left. casts of organisms or parts of them are formed by filling shells or molds with sediment or with mineral matter carried in solution by underground water. only rarely have casts of wholly soft animals been found in ancient rocks. in other cases both original form and structure are preserved, but none of the original material. this is known as petrifaction which takes place when a plant or hard part of an animal has been replaced, particle by particle, by mineral matter from solution in underground water. not uncommonly organic matter, such as wood, or inorganic matter, such as carbonate of lime shells, has been so perfectly replaced that the original structures are preserved almost as in life. the popular idea that petrified wood is wood which has been changed into stone is, of course, incorrect. it is doubtful if flesh has ever been truly petrified. in many cases mainly the carbon only of organisms has been preserved. this is also true of plants where, under conditions of slow chemical change or decomposition, the hydrogen and oxygen mostly disappear, leaving much of the carbon with original structures often remarkably preserved. fine examples are fossil plants in the great coal-bearing strata. much more rarely entire organisms have been preserved either by freezing or by natural embalmment. most remarkable are the species of mammoths and rhinoceroses, extinct for thousands of years, bodies of which, with flesh, hide, and hair still intact, have been held in cold storage in the frozen soils of siberia, or other cases. insects have been perfectly preserved in amber, as, for example, in the baltic region. this amber is a hardened resin in which the insects were caught while it was still soft and exuding from the trees. finally, we should mention the preservation of tracks and trails of land and water animals. thousands of tracks of long-extinct great reptiles occur in the sandstones and shales of the connecticut valley of massachusetts. the footprints were made in soft sandy mud which hardened and then became covered with more sediment. few fossils occur in other than the sedimentary rocks. most numerous, by far, are fossils in rocks of marine origin, because on relatively shallow sea bottoms, where sediments of the geologic ages have largely accumulated, the conditions for fossilization have been most favorable. among the many conditions which have produced great diversity in numbers and distribution of marine organisms during geologic time are temperature, depth of water, clearness of water, nature of sea bottom, degree of salinity, and food supply. river and lake deposits also not uncommonly contain remains of organisms which inhabited the waters, but also others which were carried in. "surrounding trees drop their leaves, flowers, and fruit upon the mud flats, insects fall into the quiet waters, while quadrupeds are mired in mud or quicksand and soon buried out of sight. flooded streams bring in quantities of vegetable debris, together with carcasses of land animals drowned by the sudden rise of the flood" (w. b. scott). in the study of the many changes which have taken place in the history of the earth, a fundamental consideration is the determination of the relative ages of the rocks, especially the strata. how can the geologist assign a rock formation of any part of the earth to a particular age in the history of the earth? how can it be proved that certain rock formations in various parts of the earth originated practically at the same time? there are two important criteria. first, in any region where the strata have not been disturbed from their normal order, the older strata underlie the younger because the underlying sediments must have been deposited first. now, the total thickness of the stratified series of the earth has been estimated to be no less than , feet and only a small part of this is actually present in any given locality or region. it is, therefore, evident that the order of superposition of strata is in itself not sufficient for the determination of the relative ages of all the strata in even a considerable portion of a single continent, not to mention its utter inadequacy in building up the geological column of the whole earth. when, however, the second criterion, namely, the fossil content of the strata, is used in direct connection with the order of superposition, we have the real basis for determining the relative ages of strata for all parts of the earth. the discovery of this method was very largely due to the painstaking field work in england by william smith about the beginning of the nineteenth century. it is a well-established fact that organisms have inhabited the earth for many millions of years and that, through the geologic ages, they have continuously changed, with gradual development of higher and higher types. tens of thousands of species have come and gone. accepting this fact, it is then clear that strata which were formed at notably different times must contain notably different fossils, while strata which accumulated at practically the same time contain similar fossils, allowing, of course, for reasonable differences in geographical distribution of organisms as at the present time. each epoch of earth history or series of strata has its characteristic assemblage of organisms. in short, "a geological chronology is constructed by carefully determining, first of all, the order of superposition of the stratified rocks, and next by learning the fossils characteristic of each group of strata.... the order of succession among the fossils is determined from the order of superposition of the strata in which they occur. when that succession has been thus established, it may be employed as a general standard" (w. b. scott). it should, however, be borne in mind that precise contemporaneity of strata in widely separated districts can rarely, if ever, be determined because of the very great length of geologic time and the general slowness of the evolution of organisms. rocks carrying remarkably similar fossils may really be several thousand years different in age; but this is, indeed, a very small limit of error when one considers the vast antiquity of the earth. much very accurate and satisfactory work has been done, especially in europe and north america, in correlating strata and assigning them to their places in the geological time table (see below), but a vast amount of work yet remains to be done before the task is complete. certain types or species of organisms are much more useful than others in the determination of earth chronology. best of all for world-wide correlations are species which were widely distributed and which persisted for relatively short times. thus any species which lived in the surface waters of the ocean and was easily distributed over wide areas, while, at the same time, it existed as such only a short time, is the best type of chronologic indicator. the known history of the earth has been more or less definitely divided into great eras and lesser periods and epochs, constituting what may be called the geologic time scale. in the accompanying table the era and period names, except those representing earlier time, are mostly world-wide in their usage. epoch names, being more or less locally applied, are omitted from the table. very conservative estimates of the length of time represented by the eras and the most characteristic general features of the life of the main divisions are also given. principal divisions of geologic time (modified after u. s. geological survey.) ========================================================================= | | |millions era. | period. | characteristic life. |of years | | |estimated -----------+--------------+------------------------------------+--------- | |"age of man." animals and plants | |quaternary. |of modern types. | +--------------+------------------------------------+ cenozoic | |"age of mammals." rise of highest | to . |tertiary. |animals except man. rise and | | |development of highest orders of | | |plants. | -----------+--------------+------------------------------------+--------- | |"age of reptiles." rise and | |cretaceous. |culmination of huge land reptiles | | |(dinosaurs), of shellfish with | | |complexly partitioned coiled | +--------------+shells (ammonites), and of great | | |flying reptiles. first appearance | mesozoic |jurassic. |(in jurassic) of birds and mammals; | to . | |of cycads, an order of palm-like | +--------------|plants (in triassic); and of | | |angiospermous plants, among | |triassic. |which are palms and hardwood | | |trees (in cretaceous). | -----------+--------------+------------------------------------+--------- | |"age of amphibians." dominance of | |permian. |club mosses (lycopods) and plants | +--------------+of horsetail and fern types. | | |primitive flowering plants and | |pennsylvanian.|earliest cone-bearing trees. | | |beginnings of back-boned land | +--------------+animals (land vertebrates). insects.| |mississippian.|animals with nautiluslike coiled | | |shells (ammonites) and sharks | | |abundant. | +--------------+------------------------------------+ | |"age of fishes." shellfish | |devonian. |(mollusks) also abundant. rise of | | |amphibians and land plants. | +--------------+------------------------------------| | a {|shell-forming sea animals dominant, | | g {|especially those related to | | e {|the nautilus (cephalopods). rise | paleozoic | {|and culmination of the marine | to . |silurian. o {|animals sometimes known as sea | | f {|lilies (crinoids) and of giant | | {|scorpionlike crustaceans | | i {|(eurypterids). rise of fishes and | | n {|of reef-building corals. | +-----------n-{+------------------------------------+ | v {|shell-forming sea animals, | | e {|especially cephalopods and | |ordovician.r {|mollusk-like brachiopods, abundant. | | t {|culmination of the buglike marine | | e {|crustaceans known as trilobites. | +-----------b-{+------------------------------------+ | r {|trilobites and brachiopods most | |cambrian. a {|characteristic animals. seaweeds | | t {|(algæ) abundant. no trace of | | e {|land animals found. | -----------+-----------s-{+------------------------------------+--------- | |first life that has left distinct | proterozoic|algonkian. |record. crustaceans, brachiopods, | | |and seaweeds. | -----------+--------------+------------------------------------+ | |organic matter in form of graphite | to + archeozoic |archean. |(black lead), but no determinable | | |fossils found. | -----------+--------------+------------------------------------+--------- the length of time represented by human history is very short compared to the vast time of known geological history. the one is measured by thousands of years, while the other must be measured by tens of millions of years. just as we may roughly divide human history into certain ages according to some notable person, nation, principle, or force as, for example, the "age of pericles," the "roman period," the "age of the french revolution," or the "age of electricity," so geologic history may be subdivided according to great predominant physical or organic phenomena, such as "the appalachian mountain revolution" (toward the end of the paleozoic era), the "age of fishes" (devonian period), or the "age of reptiles" (mesozoic era). in the study of earth history, as in the study of human history, it is important to distinguish between events and records of events. historical events are continuous, but they are by no means all recorded. records of events are often interrupted and seemingly sharply separated from each other. chapter ii weathering and erosion all rocks at and near the surface of the earth crumble or decay. the term "weathering" includes all the processes whereby rocks are broken up, decomposed, or dissolved. a mass of very hard and seemingly indestructible granite, taken from a quarry, will, in a very short time, geologically considered, crumble (plate ). during the short span of the ordinary human life weathering effects are generally of very little consequence, but during the long ages of geologic time the various processes of weathering have been slowly and ceaselessly at work upon the outer crust of the earth, and such tremendous quantities of rock material have been broken up that the lands of the earth have everywhere been profoundly affected. most of us have noticed buildings and monuments in which the stones show marked effects of weathering. a good case in point is westminster abbey, london, in which many of the stones are badly weathering, some of the more ornamental parts having crumbled beyond recognition since the building was erected in the thirteenth century. in many countries, tombstones and monuments only one or two centuries old are so badly weathered that the inscriptions are scarcely if at all legible. what are some of the processes of nature whereby rocks are weathered? in cold countries, and often in mountains of generally mild climate regions, the alternate freezing and thawing of water is a potent agency in breaking up rocks where the soils are thin or absent. on freezing, water expands about one-tenth of its volume and exerts the enormous pressure of over , pounds per square inch. nearly all relatively hard rock formations are separated into more or less distinct blocks by natural cracks called "joints" (plate ). very commonly the rocks also contain minute crevices, fissures, and pores. repeated freezing and thawing of water which finds its way into such openings finally causes even the most resistant rocks to break up into smaller and smaller fragments. a very striking example of difference in climatic effect upon a given rock mass is the obelisk in central park, new york. for many centuries this famous monument stood practically without change in the dry, frostless climate of egypt, but very soon after its removal to the moist, frosty climate of new york, it began to crumble so rapidly that it was necessary to cover it with a coating of glaze to protect it from the atmosphere. temperature change, especially in dry regions, is also an important agency for mechanical breaking up of rocks. on high mountains and on deserts, a daily range of temperature of from degrees to degrees is frequent. due to heat absorption, rocks in desert regions, during the day, not uncommonly reach temperatures of fully degrees, while during the night, due to heat radiation, their temperature falls greatly. during the heating of the outer portion of the rock, the various minerals each expand differently, thus setting up a series of stresses and strains tending to cause the minerals to pull apart. the outer portions of the rocks which are subjected to unstable and relatively rapid temperature changes, often crack or peel off in slabs or flakes, this process being called exfoliation. stone mountain in georgia, and some of the mountains of the southern sierra nevada range in california, are excellent examples of mountains which are being rounded off by exfoliation. the principle is the same as that which causes the "spalling" of stones in buildings during fires. masses of débris consisting of more or less angular rock fragments of all sizes commonly occur at the bases of cliffs and mountains. they represent materials which have weathered off the ledges mainly by frost action and temperature changes. where electrical storms are frequent, lightning often shatters portions of rock ledges. many such cases have come under the writer's observation in the adirondack mountains of new york. the total effect of lightning as a weathering agency is, however, relatively small. another minor weathering effect is the mechanical action of plants. the principle is well illustrated by the breaking or tilting of sidewalks by the wedging action of the growing roots of trees. in many places the roots of plants growing in cracks in rocks, exert powerful pressure causing the rocks or blocks of rocks to wedge apart. let us now briefly consider some of the chemical processes of weathering. the solvent effect of perfectly pure water upon rocks is very slight and slow. but such water is not found in nature because certain atmospheric gases, especially oxygen and carbonic acid gas, are always present in it, and they notably increase the solvent power of the water. such water has the power to slowly but completely dissolve the common rock called limestone which consists of carbonate of lime. this material is then carried away by the streams. rocks, like certain sandstones which contain carbonate of lime cementing material, are caused to crumble due to removal of the cement in solution. carbonic acid gas in water also has the power to chemically alter various minerals in many common rocks and thus the rocks fall apart and the carbonates which result from the action usually are carried away in solution. one of the most important changes of this kind takes place when the very common mineral feldspar is attacked by water containing carbonic acid gas and the mineral alters to a soluble carbonate, kaolin (or clay) and silica. the oxygen, both of the air and that which is contained in water, is a very important chemical agent of decomposition of many rocks. water at the surface and the upper part of the crust of the earth as well as moisture in the air are also important chemical agents which bring about rock decay. we are all familiar with the rusting of iron which is due to the chemical union of the iron with oxygen, thus forming an iron oxide which in turn commonly unites with water from air or earth. now, many rocks contain iron, not as such, but held in combination with other substances in the form of various minerals, and this iron of the rocks, where subjected to the oxygen and moisture of air or water, slowly unites with the oxygen and water to form a hydrated iron oxide which is essentially iron-rust. the minerals containing considerable iron are, therefore, decomposed and the rocks crumble. there are various iron oxides, usually more or less hydrated, ranging in color from red through brown to yellow, and these constitute probably the most common and striking colors of the rocks of the earth. the gorgeously colored grand canyon of the yellowstone river is a very fine example of large scale coloring due to development of much hydrated oxide of iron during the weathering of lava rock, the process having been aided by the action of heated underground waters. most of the soils of the earth are the direct result of weathering. important exceptions are soils which have been transported by the action of water, ice, or wind. although the process of weathering is very slow and relatively superficial, it is, nevertheless, true that in many places, the products of weathering form faster than they can be carried away. such weathered materials accumulate in their place of origin to form soils. the upper few hundred feet of the earth's crust is everywhere more or less fractured and porous and the rocks are there affected in varying degrees by most of the ordinary agents of weathering. in such cases, outside the areas which were recently covered by ice during the great ice age, it is common to find the loose soil grading downward into rotten rock, and this in turn into the fresh practically unaltered bedrock. soils of this kind are generally not more than ten or twenty feet deep, though under exceptional conditions, as in parts of brazil, they attain depths of several hundred feet. in order to make still clearer some of the above principles of weathering and also to give the reader some understanding of the most common types of residual soils, we shall consider what happens to a few rather definite types of ordinary rocks when they are subjected to weathering. a very simple case is that of a sandstone, the mineral grains (mostly quartz) of which are held together by carbonate of lime. the lime simply dissolves and is carried away, while many of the mineral grains may remain to form a soil of nearly pure sand. where oxide of iron forms the cementing material, the rock yields less readily to weathering, and the sandy soil will be yellowish brown or red according to the climate. another simple case is that of limestone which when perfectly pure yields no soil because it is all soluble. pure limestone is, however, rare, and the various mineral impurities in it, being to a considerable degree insoluble, tend to remain to form a residual soil which may vary from sandy to clayey, and usually brown or red due to the setting free of oxides of iron. according to one estimate a thickness of about feet of a certain fairly impure limestone formation in virginia must weather to yield a layer of soil one foot thick. soils of this kind, which are usually rich, are common in many limestone valleys of the appalachian mountains. in the case of shale rock, which is hardened mud, the cementing materials are removed, some chemical changes in the minerals may take place, and the rock crumbles to a claylike soil. what happens to a very hard, resistant igneous rock like granite when attacked by the weather? such a rock always consists mainly of the two very common minerals feldspar and quartz, usually with smaller amounts of other minerals such as mica, hornblende, augite, or magnetite. the feldspar, which when fresh is harder than steel, slowly yields when attacked by water containing carbonic acid gas and crumbles or decays to a mixture of kaolin (clay), carbonate of potash, and silica (quartz). clay is an important constituent of most good soils, while the carbonate of potash is essential as a food for most plants. due to yielding of the grains or crystals of feldspar, the granite falls apart (see plate ). the grains of quartz remain chemically unchanged, though they may be more or less broken by changes of temperature, and the other minerals, which are mostly iron-bearing, yield more or less to weathering, resulting in a variety of products, among which are oxides of iron. a typical granite, therefore, gives rise to a good heavy soil which is yellow, brown or red according to climate. such granite soils are common in many parts of the piedmont plateau from maryland to georgia. most of the dark-colored igneous rocks, like ordinary basaltic lava, contain much feldspar, various iron-bearing minerals, and little or no quartz. such rocks yield to the weather like granite but, because of lack of quartz, the soils are more clayey. rich soils of this kind occur in the great lava fields of the northwestern united states and in the hawaiian islands. the importance of the breaking down of feldspar under the influence of the weather, as above described, not only from the standpoint of soil development, but also as regards the wearing down of the lands of the earth, is difficult to overemphasize because that mineral is by far the most abundant constituent of the earth's crust. the term "erosion" is one of the most important in geologic science. it comprises all the processes whereby the lands of the earth are worn down. it involves the breaking up of earth material, and its transportation through the agency of water, ice, or wind. weathering, including the various subprocesses as above described, is a very important process of erosion. by this process much rock material is got into condition for transportation. another process of erosion, called "corrasion," consists in the rubbing or bumping of rocks fragments of all sizes carried by water, ice, or wind against the general country rock, thus causing the latter to be gradually worn away. a fine illustration of exceedingly rapid corrasion of very hard rock was that of the sill tunnel in austria, which was paved with granite blocks several feet thick. water carrying large quantities of rock fragments over the pavement at high velocity caused the granite blocks to be worn through in only one year. ordinarily in nature, however, the rate of wear is much slower than this. pressure exerted upon the country rock by any agency of transportation may cause relatively loose joint blocks, into which most rock formations are separated, to be pushed away. this process, called "plucking," is especially effective in the case of flowing ice. chapter iii stream work most streams are incessantly at work cutting or eroding their way into the earth's crust and carrying off the products of weathering. by this means the general level of lands is gradually being reduced to nearer and nearer sea level. base level of erosion is reached when any stream has eroded to its greatest possible depth, and a whole region is said to be base-leveled when, by the action of streams, it has been reduced to a practically flat condition. a region of this kind is known as a "peneplain." to one who has not seriously considered the matter, the power of even moderately swift water to transport rock débris seems incredible. a well-established law of transportation by running water is that the transporting power of a current varies as the sixth power of its velocity. for example, a current which is just able to move a rock fragment of a given size will, when its velocity is merely doubled, be able to move along a piece of similar rock sixty-four times as large! that this must be the case may be readily proved as follows: a current of given velocity is just able to move a block of rock, say, of one cubic inch in the form of a cube. a cubic block sixty-four times as large has a face of sixteen square inches. by doubling the velocity of the current, therefore, twice as much water must strike each of the sixteen square inches of the face of the larger block with twice the force, thus exerting sixty-four times the power against the face of the larger block, or enough to move it along. this surprising law accounts for the fact that in certain floods, like the one which rushed over johnstown, pennsylvania, in , locomotives, massive iron bridges, and great bowlders were swept along with great velocity. it is obvious, then, that ordinarily swift rivers in time of flood accomplish far more work of erosion (especially transportation) than during many days or even some months of low water. few people have the slightest idea as to the enormous amount of earth material which the rivers are carrying into the sea each year. the burden carried by the mississippi river has been carefully studied for many years. each year this river discharges about , , tons of material in suspension; , , tons in solution; and , , tons rolled along the bottom. this all represents earth material eroded from the drainage basin of the river. it is sufficient to cover a square mile feet deep, or if placed in ordinary freight cars it would require a train reaching around the earth several times to contain it. since the drainage basin of the mississippi covers about , , square miles, it is, therefore, evident that this drainage area is being worn down at the average rate of about one foot in , years, and this is perhaps, a fair average for the rivers of the earth. the ganges river, being unusually favorably situated for rapid erosion, wears down its drainage basin about one foot in , years. it has been estimated that nearly , , tons of material are annually carried into the sea by the rivers of the united states. according to this the country, as a whole, is being cut down at the rate of about one foot in , years. in arriving at this figure it should, of course, be borne in mind that the average level of hundreds of thousands of square miles of the western united states, particularly the so-called great basin, is practically not being reduced at all because none of the streams there reach the sea. deposition of sediment is an important natural consequence of erosion. the destination of most streams is the sea, and where tides are relatively slight the sediments discharged mostly accumulate relatively near the mouths of the rivers in the form of flat, fan-shaped delta deposits. some rivers, like the ganges, which carry such unusual quantities of sediment, are able to construct deltas in spite of considerable tides. deltas also form in lakes. in most cases, however, rivers enter the sea where there are considerable tides and their loads are more widely spread over the marginal sea bottom. but in many cases some of the sediment does not reach the mouth of the stream. it is, instead, deposited along its course either where the velocity is sufficiently checked, as is the case over many flood-plain areas of rivers, or where a heavily loaded, relatively swift stream has its general velocity notably diminished. an excellent example of the latter type of stream is the platte river, which is swift and loaded with sediment in its descent from the rocky mountains, but, on reaching the relatively more nearly level nebraska country, it has its current sufficiently checked to force it to deposit sediment and build up its channel along many miles of its course, and this in spite of the fact that it still maintains a considerable current. in a mountainous arid region a more or less intermittent stream at times of flood becomes heavily loaded with rock débris and rushes down the mountain side. on reaching the valley floor the velocity is greatly checked and most of the load is deposited at the base of the mountain, successive accumulations of such materials, called alluvial cones or fans, having not uncommonly built up to depths of hundreds, or even several thousand feet. [illustration: plate .--(_a_) granite weathering to soil near northampton, mass. under the action of weathering all of the once hard, fresh, mass of granite has crumbled to soil except the fairly fresh rounded masses which are residual cores of "joint blocks." (_photo by the author._)] [illustration: plate .--(_b_) looking-glass rock, utah. the rock is stratified sandstone sculptured mainly by wind erosion, that is, by the wind driving particles of sand against it. (_photo by cross, u. s. geological survey._)] [illustration: plate .--grand canyon of the yellowstone river in yellowstone national park. the great waterfall feet high is shown. the large swift river has here sunk its channel (by erosion) to a maximum depth of , feet during very recent geological time, and the process is still going on. the wonderful coloring is due to iron oxides set free during weathering of the lava rock. (_photo by hillers, u. s. geological survey._)] any newly formed land surface, like a recently drained lake bed or part of the marginal sea bottom which has been raised into land, has a drainage system developed upon it. in the early or youthful stage of such a new land area lying well above sea level, under ordinary climatic conditions a few streams only form and these tend to follow the natural or initial slope of the land. these streams carve out narrow, steep-sided valleys, and all of them are actively engaged in cutting down their channels, or, in other words, none of them have reached base level, and flood plains and meandering curves are therefore lacking. during this youthful stage there are no sharp drainage divides; gorges and waterfalls are not uncommonly present; and the relief of the land in general is not rugged. a good example of youthful topography is the region around fargo, north dakota, which is part of the bed of a great recently drained lake. the grand canyon of the yellowstone river is an excellent illustration of a youthful valley cut in a high plateau of geologically recent origin. (plate .) as time goes on, a region in youth gradually gives way to a region in maturity, during which stage the maximum number (usually a network) of streams in broader v-shaped valleys have developed; divisions of drainage are sharp; the maximum ruggedness of relief has developed; the larger streams only have cut down so near base level that winding (meandering) courses and flood plains are well developed along them; and waterfalls and gorges are rarely present. an almost perfect example of a region in maturity is that around charleston, west virginia. the old-age stage develops next in the history of the region, during which only a moderate number of streams remain, most of these being at or close to base level so that sweeping curves or meanders (plate ) and cut-off meanders or "ox bows" and wide flood plains are characteristic and common. the relief is greatly subdued and the term "rolling country" might be applied to the moderately hilly region. divisions of drainage are, of course, not at all sharp and the valleys are wide and shallow. oxbow lakes are common, but gorges and waterfalls are absent. a region typical of old-age topography is that around caldwell, kansas. finally, after the remaining low hills have been cut down, the region is in the condition of a broad monotonous plain, practically devoid of relief, over which the sluggish streams pursue very winding, more or less shifting or indefinite courses. for the attainment of this final stage (called a "peneplain") in the normal cycle of erosion a proportionately very long time is necessary, because the rate of erosion becomes slower and slower as the region is being cut down. then, too, some change of level between the land and the sea is very likely to take place before the peneplain stage is reached. it is doubtful if any extensive region was ever brought to the condition of a perfect peneplain. some masses of more resistant or more favorably situated rocks are almost sure to maintain at least moderate heights above the general plain level. geologically recently upraised, fairly well developed peneplains are southern new england and the great region of eastern canada. the remarkably even sky lines of these regions mark the peneplain level before the uplift took place, and occasionally masses, called "monadnocks" from mount monadnock in southern new hampshire, rise above the general level. the valleys in such an uplifted peneplain region have been carved out by streams since the uplift began. we have positive evidence that more or less well-developed peneplains of considerable extent existed in various parts of the earth at various times during the many millions of years of known earth history. the normal cycle of erosion which, as outlined above, tends toward the peneplain condition may be interrupted at any stage by other processes. an excellent case in point is the upper mississippi valley, which had reached the old-age stage, even approximating a peneplain, just before the great ice age. then, during the withdrawal of the vast sheet of ice from the region toward the close of the ice age, extensive deposits (moraines, etc.) of glacial débris were left irregularly strewn over the country, giving rise to many low hills, lake basins, and altered drainage lines, in some cases with resultant gorge development. some distinct features of a youthful topography are, therefore, plastered over what was otherwise a region well along in old age. the general district around the dells of wisconsin river well illustrates this principle. changes in level between land and sea which take place during the erosion of a region may also disturb the normal cycle of erosion. for example, a region in old age may be considerably upraised so that the streams have their velocities notably increased. such a region is said to be "rejuvenated" and the streams, which are revived in activity, begin to cut youthful valleys in the bottom of the old ones and, after a time, the general surface of the region is subjected to vigorous erosion and a new cycle of erosion will be carried out unless interfered with in some way, as by relative change of level between the land and the sea. in this connection the history of the topography in the general vicinity of harrisburg, pennsylvania, may be of interest by way of illustration of the principle just described. the long, narrow, parallel appalachian mountain ridges there rise to about the same level, causing a remarkably even sky line as viewed from one of the summits. this even sky line marks approximately the surface of what was a peneplain late in the mesozoic era. early in the succeeding cenozoic era, the broad peneplain was notably upraised to nearly the present altitudes of the ridge tops. the revived susquehanna river left the old course which it had on the peneplain surface, and began to carve out its present valley, while tributaries (subsequent streams) to it developed along belts of weaker rock and thus they formed the present parallel valleys separated by belts of more resistant rocks which stand out as ridges. in this way, the mature stage of topography was reached. very recently, geologically, the region has been rejuvenated enough to cause the larger streams to appreciably sink their channels below the general valley floors. the reader will find a general discussion of movements of the earth's crust in a succeeding chapter. [illustration: fig. .--the submerged hudson river channel is clearly shown by the contour lines on the sea floor. figures indicate depth of water in fathoms. geologically recent sinking of the land has caused the "drowning" of the river valley. (coast and geodetic survey).] if, for example, a region along the seaboard has reached the mature stage of erosion, and the land notably subsides relative to sea level, the tidewater will enter the lower valleys to form estuaries and the valleys are said to be "drowned." the large streams, or at least their lower courses, are thus obliterated and also the general erosion of the region is distinctly diminished. the recently sunken coast of maine well illustrates the idea of "drowned valleys." the drowned valley of the lower hudson river is another fine example. [illustration: fig. .--sketch maps showing how the shenandoah river captured the upper waters of beaverdam creek in virginia. the abandoned valley of the creek across blue ridge is now called a "wind gap." (after b. willis.)] what is termed stream "piracy" is of special interest in connection with stream work. by this is meant the stealing of one stream or part of a stream by another. we shall here explain only one of the various ways by which stream capture may be effected. one of two fairly active streams, flowing roughly parallel to each other, is more favorably situated and has cut its channel deeper. its tributaries are, therefore, more favorable to extension of headwaters and, in time, one of its tributaries eats back far enough to tap a branch of the less favorably situated stream so that the waters of this branch are diverted into the more favorably situated stream. the shenandoah river of virginia has been such a pirate. this river developed as a tributary of the potomac. by headward extension toward the south, the shenandoah finally tapped and diverted the upper waters of the smaller, less favorably situated beaverdam creek. the notch or so-called "wind gap" through which the upper waters of beaverdam creek formerly flowed across the blue ridge is still plainly visible. such abandoned water gaps, known as "wind gaps," are common in the central appalachian mountain region. a remarkable type of river is one which has been able to maintain its course through a barrier, even a mountain range, which has been built across it. thus, the columbia river, after flowing many miles across the great lava plateau, has maintained its course right across the growing cascade range by cutting a deep canyon while the mountain uplift has been in progress. in a similar manner the ogden river of utah has kept its westward course by cutting a deep canyon into the wasatch range which has geologically recently, though slowly, risen across its path. in no other way can we possibly explain the fact that such a river, rising on one side of a high mountain range, cuts right across it. a feature of minor though considerable popular interest is the development of "potholes" by stream action. where eddies occur, in rather active streams, rock fragments of varying sizes may be whirled around in such manner as to corrode or grind the bedrock, resulting in the development of cylinder-shaped "potholes." such holes vary in diameter up to fifty feet or more in very exceptional cases. in the production of large "potholes" many rock fragments are worn away and new ones supplied to continue the work. locally, some stream beds are honeycombed with "potholes." [illustration: fig. .--grand canyon, arizona. (from darton's "story of the grand canyon.")] strikingly narrow and deep valleys, called gorges and canyons, are rather exceptional features of stream action. most wonderful of all features of this kind is the grand canyon of the colorado river in arizona. in fact, this canyon takes high rank among the most remarkable works of nature. the canyon is over miles long, from , to , feet deep, and from to miles wide. contrary to popular opinion, this mighty canyon is not a result of some violent process, such as volcanic action, or the sudden sinking of part of the earth's crust. nor is it the result of the scouring action of a great glacier. it is simply a result of the operation of the ordinary processes of erosion where the conditions have been exceptionally favorable. some of the favorable conditions have been, and are, a large volume of very swift water (colorado river) continually charged with an abundance of rock fragments for the work of corrasion, and a great thickness of rock which the river must cut through before reaching base-level. aridity of climate also tends to preserve the canyon form. the whole work has been accomplished in very late geological time, and the tremendous volume of rock which has been weathered and eroded to produce the canyon has all been carried away by the colorado river and accumulated in the great delta deposit near where the river empties into the gulf of california. even now the canyon is growing deeper and wider because the very active colorado river is still from , to , feet above sea level. standing on the southern rim near grand canyon station at an altitude of nearly , feet, and looking down into the canyon, one beholds a vast maze of side canyons, high, vertical rock walls which follow very sinuous courses, giving rise to a steplike topography, and countless rock pinnacles, towers, and mesas often of mountain-like proportions. the side canyons are the result of erosion by tributaries to the main river which have gradually developed and worked headward as the main river has cut down. the mountain-like sculptured forms which rise out of the canyon are erosion remnants, or, in other words, masses of rock which were more favorably situated against erosion by either the main river or any of its tributaries. all of the rocks of the broader, main portions of the canyon are strata of paleozoic age, arranged as a vast pile of almost horizontal layers, including sandstone, limestone, and shale. some of these layers, being distinctly more resistant than others, stand out in the canyon wall in the form of conspicuous cliffs, in some cases hundreds of feet high. the very striking color bands (mostly light gray, red, and greenish gray), which may be traced in and out along the canyon sides, represent the outcropping edges of variously colored rock layers. far down in the canyon lies the steep-sided, v-shaped inner gorge, or canyon which is fully , feet deep. the rocks are there not ordinary strata, but rather metamorphic and igneous rocks, mostly dark gray, not in layers, and about uniformly resistant to erosion. there is reason to believe that this inner gorge has developed mainly since a distinct renewed uplift (rejuvenation) of the colorado plateau after the river began its canyon cutting. the narrow, steep-sided inner gorge may thus be readily accounted for and the general lack of steplike forms on its sides is due to essential uniformity of the rock material as regards resistance to erosion. [illustration: fig. .--profile and structure section across the line a-a in fig. . length of section miles, vertical scale not exaggerated. the main relief features, and the relations of the rocks below the surface are shown. the granite and gneiss are of archeozoic age, and the overlying nearly horizontal strata are of paleozoic age. (after darton, u. s. geological survey.)] the wonderful king's river canyon of the southern sierras in california is remarkable for its combined narrowness and depth. it is a steep v-shaped canyon whose maximum depth is , feet, carved out in mostly solid granite by the action of weathering and running water. some idea of the vast antiquity of the earth may be gleaned from the fact that this tremendously deep canyon has been produced by erosion in one of the most resistant of all known rocks in very late geologic time! conditions favorable for cutting this canyon have been volume and swiftness of water and a liberal supply of grinding tools. among the many other great canyons of the western united states brief mention may be made of the grand canyon of the yellowstone river in the national park. the plateau into which the river has cut its steep-sided, narrow, v-shaped canyon, with a maximum depth of , feet, has been geologically recently built up by outpourings of vast sheets of lava. the large volume of very swift water, aided by decomposition and weakening of the ordinarily very hard rock by the action of the hot springs, has been able to carve out this deep canyon practically within the last period of earth history. the deepening process is still vigorously in progress. the wonderful coloring of the rock, mostly in tones of yellow and brown, is due to the hydrated iron oxides developed during the decay of the iron-bearing minerals of the lava, the chemical action having been greatly aided by the action of the hot waters. (see plate .) in regard to its origin, the marvelous yosemite valley, or canyon, falls in a somewhat different category, and it is discussed beyond in connection with the work of ice. suffice it to say here that running water has been a very important factor in its origin. in new york and new england there are many gorges which have developed by the action of running water since the great ice age. famous among these are ausable chasm and watkins glen of new york, and the flume in the white mountains of new hampshire. [illustration: fig. .--sketch map showing the retreat of the crest of niagara falls from to , based upon actual surveys. the retreat of the inner part of the horseshoe fall was more than feet. (modified by the author after gilbert, u. s. geological survey.)] before leaving our discussion of the work of running water, we should briefly consider waterfalls. true waterfalls originate in a number of ways. most common of all is what may be termed the "niagara type" of waterfall. niagara falls merit more than passing mention not only because of their scenic grandeur, but also because of the unusual number of geologic principles which their origin and history so clearly illustrate. niagara falls are divided into two main portions, the canadian, or so-called "horseshoe fall," and the "american fall," separated by a large island. the crest of the american fall is about , feet long and nearly straight, while the crest of the canadian fall is notably curved inward upstream, and it is about , feet long. the height of the falls is feet. downstream from the falls there is a very steep-sided gorge about feet deep and seven miles long. the exposed rocks of the region are nearly horizontal layers of limestone underlain with shales. relatively more resistant limestone forms the crest of the falls, and directly underneath are the much weaker shales. herein lies the principle of this type of waterfall because, due to weathering and the swirling action of the water, the weaker underlying rocks erode faster, thus causing the overlying rock to overhang so that from time to time blocks of it already more or less separated by cracks (joints), fall down and are mostly carried away in the swift current. thus the waterfall maintains itself while it steadily retreats upstream. careful estimates based upon observations made between and show that the canadian fall retreated at the rate of from three to five feet per year, while the american fall retreated during the same time at the rate of only several inches per year. it has been well established that niagara falls came into existence soon after the ice of the great ice age had retreated from the district. the falls started by plunging over a limestone escarpment, situated at what is now the mouth of the gorge seven miles downstream from the present falls. if we consider the rate of recession of the falls to have been always five feet per year, the length of time required to cut the gorge would be something over , years. but the problem is not so simple, because we know that, at the time of, or shortly after, the beginning of the falls, the upper great lakes drained farther north and not over the falls; and that this continued for a considerable, though unknown, length of time. during this interval the volume of water in niagara river was notably diminished, and hence the recession of the falls must have been slower. on the other hand, judging by the width of the gorge, the length of the crest of the falls has generally been considerably less than at present, which in turn means greater concentration of water over the crest and more rapid wear. various factors considered, the best estimates for the age of the falls vary from , to , years, an average being about , years. although this figure is not precise, it is, nevertheless, of considerable geologic interest because it shows that the age of niagara falls (and gorge) is to be reckoned in some tens of thousands of years, rather than hundreds of thousands or millions of years. although waterfalls of the niagara type are the most common of all, it is by no means necessary that the particular rocks should be limestone and shale. another common kind of waterfall may be termed the "yosemite type," so named from the high falls in the yosemite valley of california. at the great falls of the yosemite, the rock is a homogeneous granite and the undermining process does not operate. yosemite creek first plunges vertically over a granite cliff for , feet to form the upper falls, which must rank among the very highest of all true water falls. the water then descends about feet by cascading through a narrow gorge, after which it makes a final vertical plunge of over feet. a brief history of the falls is about as follows. a great steep-sided v-shaped canyon several thousand feet deep had been carved out by the action of the merced river which now flows through the valley. then, during the ice age, a mighty glacier plowed through the canyon, filling it to overflowing. the granite of this district having been unusually highly fractured by great vertical joint cracks was relatively easy prey for ice erosion. due to its great weight, the erosive power of the ice was most potent toward the bottom, successive joint blocks were removed, and the valley was thus widened and the sides steepened or even commonly made practically vertical. (see plate .) after the melting of the ice, certain of the streams, like yosemite creek and bridal veil creek, were forced to enter the valley by plunging over great perpendicular, granite cliffs which are in reality joint faces. this type of waterfall does not retreat, but it constantly diminishes in height by cutting into the crest. a number of other high falls of this kind occur in the yosemite region, and also in other mountain valleys which formerly contained glaciers, as in the canadian rockies, the alps, and norway, the rocks in these regions being of various kinds. in the case of the "yellowstone type" of waterfall a different principle is involved, namely, a distinctly harder or more resistant mass of rock which extends vertically across the channel of the stream. at the great falls of the yellowstone a mass of relatively fresh, hard lava lies athwart the course of the river, while just below it the lava has been much weakened by decomposition. the harder rock therefore acts as a barrier, while, in the course of time, the weak rock on the downstream side has been worn away until a waterfall feet high has developed. this waterfall does not retreat very appreciably, but it is probably increasing in height, due both to the scouring action of the water at the base of the fall and the unusual clearness of the river water here, thus causing little wear at the crest. it should be noted, in this connection, that the channel just on the upstream side of the barrier cannot be cut down faster than the top of the barrier itself. the famous victoria falls of the zambezi river in south africa, represents a relatively uncommon type of waterfall. considering height of the fall, length of crest, and volume of water, this is perhaps the greatest waterfall in the world. the zambezi river, a mile wide, plunges over feet vertically into a chasm only a few hundred feet wide and at right angles to the main course of the stream. the general country rock is hard lava, but locally a narrow belt of the rock has been highly fractured vertically, due to earth movements or faulting (see explanation beyond) and therefore weakened and more subject to weathering than the general body of the lava rock. this belt of weakened rock has been easy prey for erosion by the zambezi river and the chasm has there developed. in fact the chasm is still being increased in depth. leaving the chasm toward one end, the river flows through a narrow zig-zag gorge whose position has been determined by big joint cracks. the mile-wide crest of the falls is interrupted by a good many ledges and even small islands. the thundering noise of this great waterfall is most impressive, but a good complete view is impossible because most of the chasm is constantly filled with dense spray. still another type of waterfall develops by the removal of joint blocks by the action of running water. falls of this type are fairly common though they seldom attain really great heights. where the rock in the bed of a stream is traversed by well-developed vertical joint cracks, slabs of rock cleaved by the joints may fall away due to weathering or they may be pushed away by pressure of the water. such a fall retreats upstream by removal of joint blocks even in comparatively homogeneous rocks. taughannock falls, feet high, in southern central new york, has developed by this manner in a shaly sandstone. the several falls (one feet high) in the famous gorge at trenton falls, in central new york, have developed in this way in limestone. chapter iv the sea and its work it is well known that the waters of the sea cover nearly three-fourths of the surface of the earth. we think of the united states as being a large piece of land of over three million square miles--but the sea is about forty-five times as large, that is, it covers approximately , , square miles. it is a remarkable fact that the average depth of the great oceans of the earth is nearly two and one-half miles. if the sea were universally present everywhere with the same depth, it would be almost two miles deep. yet this vast body of water is an extremely thin layer when compared with the earth's diameter of , miles. the pacific is the deepest of the oceans with an average depth of about two and three-fourths miles. the deepest ocean water ever sounded is , feet (over six miles), not far from the philippine islands. this is known as the planet deep, and was discovered in . second deepest is , feet near the island of guam. in the pacific ocean there are five places where the water is over five miles deep and eleven places were it is over four miles deep. the deepest sounding ever made in the atlantic ocean was , feet, not far from porto rico. many substances are known to be in solution in sea water, but in spite of this the composition is remarkably uniform. the most abundant substance by far in solution is common salt. in every pounds of sea water, there are . pounds of mineral matter of various kinds dissolved. nearly per cent of the dissolved matter is common salt. the principal other constituents in solution are chloride and sulphate of magnesia, and the sulphates of lime and potash. all other dissolved mineral substances together make up less than one per cent of the total. it has been estimated that if all the dissolved mineral matter should be brought together, it would form a layer feet thick over the whole sea bottom. the salts of the sea have been mostly supplied by the rivers, which in turn have derived them from the disintegration and chemical decay of the rocks. if we make a general comparison with the surface of the land, the floor of the ocean is a vast monotonous plain. none of the sea bottom compares with the ruggedness of mountains, and even the more level portions of land surface show many sharp minor irregularities such as stream trenches. but the sea bottom is characterized by its smoothness of surface. there are under the sea, however, mountain-like ridges, plateaus, submarine volcanoes and valleys known as "deeps." but these rarely show ruggedness of relief like similar features on land. one of the most remarkable relief features of the ocean bottom is the so-called "continental shelf." this is a relatively narrow platform covered by shallow water bordering nearly all the lands of the earth. seaward, the depth of water is greatest, and it is seldom over or feet. the continental shelves of the world cover about , , square miles or about one-fourteenth of the area of the sea. viewed in a broad way, there are two great classes of marine deposits; first, those laid down comparatively near the borders of the land, that is, on the continental shelf and continental slope, and second, the abysmal deposits laid down on the bottom of the deep ocean. those found along and near the continental borders are largely land-derived materials, that is to say, they are mostly sediments carried from the land into the sea by rivers, and to a lesser extent rock material broken up by waves along many shores. practically all such land-derived material is deposited within to miles of the shores. the continental border deposits are extremely variable. near shore they are chiefly gravel and sands, while farther out they become gradually finer, and on the continental slope only very fine muds are deposited. these deposits usually contain more or less organic materials and shells or skeletons of organisms. in some cases the shells or skeletons of organisms predominate or even exist to the exclusion of nearly all other material, as is true of the coral deposits or reefs which form only in shallow water. deposits like those just described as accumulating on the bottom of the shallow sea, comparatively near the lands, are of great significance to the geologist because just such marine deposits now consolidated into sandstone, conglomerate, shale, and limestone, are so widely exposed over the various continents. a knowledge of the conditions under which shallow sea deposits are now forming, is, therefore, of great value in interpreting events of earth history as they are recorded in similar rocks which have been accumulating through millions of years of time. one specific instance will make this matter clearer. using the method outlined in chapter i for the determination of earth chronology, and our knowledge of present conditions under which shallow sea deposits are formed, it has been well established that a shallow sea spread over fully four-fifths of the area of north america during the middle ordovician period of the early paleozoic era. beyond this main conclusion, a careful study of these rocks has revealed many important facts regarding the physical geography, life, and climate of that time. the importance of this whole matter is still further emphasized by the statement that five-sixths of the exposed rocks of the earth are strata--mostly of shallow sea origin. the deposits on the deep sea bottom are very largely either organic or the shells and skeletons of organisms which have fallen to the bottom from near the surface as already explained. most common of these are the deep sea "oozes" which are made up of the remains and shells of tiny organisms called "foraminifers." these "oozes" cover about million square miles of the sea bottom down to depths of from two to three miles. at depths greater than from two to three miles, a peculiar red clay is the prevailing deposit. this is most extensive of all, covering an area of million square miles, or nearly the total area of lands of the earth. some remains of organisms are mixed with this clay, but since most of the shells are of carbonate of lime and very thin, they are dissolved without reaching the bottom in the deep sea water which is under great pressure and rich in carbonic acid gas. the deep sea deposits, both "oozes" and red clay, do, however, contain some land-derived and other materials. thus off the west coast of africa some dust carried by the prevailing winds from the sahara desert, is known to fall in the deep sea several hundred miles from shore. volcanic dust is carried for many miles and deposited in the deep sea--particularly in the south pacific ocean. bits of porous volcanic rock called "pumice" sometimes float long distances out over the deep sea, before becoming water soaked. icebergs often drift far out from the polar regions over the deep sea, and on melting the rock débris which they carry is dropped to the sea bottom. also, particles of iron and dust from meteorites ("shooting stars") have been dredged from the deep sea. one important geological significance of the deep sea deposits is the proof which they furnish that, from at least as far back as the beginning of the paleozoic era, fully twenty-five million years ago, to the present time, the two great deep ocean basins--the atlantic and the pacific--have maintained essentially the same positions on the earth. this is proved by the fact that nowhere, on any continent among the rocks of all ages, as old at least as the early paleozoic, do we find any really typical deep-sea deposits. there is then no evidence that a deep sea ever spread over any considerable part of any continent, and this in spite of the fact that marine deposits of shallow water origin furnish abundant evidence of former sea extensions. the shallow seas have at various times spread over large portions of the continents. on many rocky coasts the waves are incessantly pounding and wearing away the rocks. in such places the sea, like a mighty horizontal saw, is cutting into the borders of the lands. the finer materials produced by the grinding up of the rocks are carried seaward by the undertow. but, if the land remains stationary with reference to the sea, this landward cutting by the waves reaches a limit. since even big waves have very little effect in water or feet deep, a shelf is cut by the waves and this shelf, not many miles wide, is covered by shallow water. the finer ground-up rock materials carried out by the undertow are dumped just beyond the edge of the shelf which is thus built out seaward as a terrace. in traveling over this shelf and terrace, the waves, due to friction, lose their power. with gradually sinking land, a much wider shelf may be cut, because the power of the waves is then allowed to continue. it might be of interest to cite a few cases of relatively rapid coast destruction by the waves which have come under human observation. a remarkable example is the island of heligoland on which is (or was) located the powerful german fort which guards the entrance to the kiel canal. in the year a. d. this island had miles of shore line; in it had miles of shore; in only miles; and in but miles of shore line remained. in southeastern england "whole farms and villages have been washed away in the last few centuries, the sea cliffs retreating from to feet a year." a church located a mile from the sea shore near the mouth of the thames river, in the sixteenth century, now stands on a cliff overlooking the sea. an island in chesapeake bay covered over acres in , and the waves have since reduced it to about fifty acres. study showed that the relatively soft unconsolidated strata of the nashaquitsa cliffs on the island of martha's vineyard, were cut back at the rate of - / feet per year, between and . if part of the relatively smooth sea bottom should be raised into land, the resulting shore line would of course, be regular and free from indentations or sharp embayments. examples of such coast which are very young are at cape nome, alaska; the northern coast of spain; and the west coast of northern south america. soon, however, such a shore line is attacked, and, either where the waves are greatest or the rocks are weakest, indentations will result and the whole coast is gradually eaten back until the power of the waves is largely spent in traveling across the shallow water shelf. sand bars are then built across the mouths of the bays or indentations which later the rivers gradually fill up with sediment. the result is a relatively straight or regular old shore line. the coast of texas has about reached this stage. if a portion of the relatively rugged land surface should become submerged under the sea, a very irregular, deeply indented shore line would result, due to the entrance of tidewater into the valleys. the deeply indented coast of maine is a fine example of a very irregular youthful shore line produced by geologically recent sinking of a rugged, hilly region so that tidewater backs for miles into the lower reaches of the river valleys. the promontories and islands are undergoing rapid wear, and the development of bars across the inlets has scarcely begun. other excellent examples are the coasts of norway and southern alaska. such a coast is then attacked by the ocean waves and the promontories are cut back until the broad shallow water shelf is formed, after which sand bars are built across the remaining embayments and the shore line becomes relatively regular. it is, then, a remarkable fact that, whether shore lines originate by emergence of sea bottom, or by sinking of land, there is a very strong tendency on the part of nature to develop regular shore lines. it should be stated that the principles of wave work and shore-form development just outlined apply almost equally well to lakes, especially large ones. before leaving this subject of shore-line development, mention should be made of the fact that bars and beaches are often built part way or wholly across embayments of the coast with surprising rapidity. to illustrate, sandy hook, new jersey, is advancing northward, while rockaway beach, new york, is extending westward, the tendency being to close up the entrance to new york harbor and to make the line of seashore more nearly regular. records show that rockaway beach actually advanced westward more than three miles between the years and . chapter v glaciers and their work a glacier may be defined as a mass of flowing ice. the motion may not be that of flowage in the usually accepted sense of the term. a discussion of the various theories of glacier motion will not here be attempted. glaciers form only in regions of perpetual snow, but they commonly move down far below the line of perpetual snow of any given region. in the polar regions they may form near sea level, while in the tropics they form at altitudes of two to three miles, and there only rarely. in southern alaska, the lower limit of perpetual snow is about , feet above sea level, and many of the glaciers come down to sea (plate ), while in the alps, the lower limit of perpetual snow is at about , feet, and the glaciers descend as much as , feet below it. in regions of perpetual snow there is a tendency for more or less snow to accumulate faster than it can be removed by evaporation or melting. as such snow accumulates it gradually undergoes a change, especially in its lower parts, first into granulated snow (so-called "névé") and then into solid ice. snow drifts in the northern united states often undergo similar transformation, after a few months first to névé, and then to ice. this transformation seems to be brought about mainly by weight of overlying snow which compacts the snow crystals; by rain or melting snow percolating into the snow to freeze and fill spaces between the snow crystals; and by the actual growth of the crystals themselves. when ice of sufficient thickness has accumulated (probably at best several hundred feet), the spreading action or flowage begins and a glacier has developed. renewed snowfalls over the gathering ground keep up the supply of ice. there are several types of glaciers: valley or alpine glaciers; cliff or hanging glaciers; piedmont glaciers; ice caps; and continental ice sheets. a valley or alpine glacier consists essentially of a stream of ice slowly flowing down a valley and fed from a catchment basin of snow within a region of perpetual snow. in the alps, where glaciers of this sort are very typically shown, they vary in length up to eight or nine miles. perhaps the grandest display of great valley glaciers is in southern alaska where they attain lengths up to forty or fifty miles and widths of one or two miles (plate ). hanging or cliff glaciers are in many ways like valley glaciers, but they are generally smaller; they develop in snow-filled basins above the snow line usually on steep mountain sides; and they do not reach down into well-defined valleys. most of the glaciers of the glacier national park in montana and many of those in the cascade mountains are of this type. mount rainier in washington is one of the most remarkable single large mountain peaks in the world, in regard to development of glaciers over it. great tongues of ice, starting mostly at , to , feet above sea level, flow down the sides of the mountain for distances of to four and even six miles. the total area of ice in this remarkable system of radiating glaciers on this one mountain is over forty square miles. these mount rainier glaciers are in general best classified as intermediate in type between valley and hanging glaciers. [illustration: fig. .--map of mount rainier, washington, showing its wonderful system of glaciers which covers more than square miles. dotted portions represent moraines. (u. s. geological survey.)] in some high latitude areas, as in iceland and spitzbergen, snow and ice may accumulate on relatively level plains or plateaus and slowly spread or flow radially from their centers. these are called ice caps. ordinary ice caps usually do not cover more than some hundreds of square miles. continental glaciers or ice sheets are, in principle, much like ice caps, but they are larger. greenland is buried under an ice sheet of moderate size (about , square miles), the motion being outward in all directions toward the sea. tongues of ice, like valley glaciers, are commonly sent off from the main body of ice across the land border of greenland into the sea. the size of the great ice sheet of antarctica is not definitely known, but it covers probably at least several million square miles. two continental ice sheets of special interest to the geologist are those which existed during the great ice age of the quaternary period. one of these then covered nearly , , square miles of north america, while the other covered about , square miles of northern europe. the main facts regarding the ice age are given in a succeeding chapter. the facts brought out in the present discussion of existing glaciers will greatly aid in understanding the ice age. how fast do glaciers flow? based upon many observations, we may say that an average rate of flow for the glaciers of the world is not more than a few feet per day. a very exceptional case is a large glacier, branching off as a tongue from the ice sheet of greenland, which is said to move sixty to seventy-five feet per day. some of the great alaskan glaciers have been found to flow from four to forty feet per day. most glaciers of the alps move only one to two feet per day. a glacier advances only when the rate of motion is greater than the rate of melting of its lower end and vice versa in the case of retreat. thus it is true, though seemingly paradoxical, to assert that a glacier has a constant forward motion even when it is retreating by melting. by watching the changing position of marked objects placed in the ice, it has been proved that, in a valley glacier, the top moves faster than the bottom; the middle moves faster than the sides; the rate of motion increases with thickness of ice, slope of floor over which it moves, and temperature. ice, like molasses candy, tends to crack when subjected to a relatively sudden force, and where the ice rides over a salient on the bed of the glacier, transverse cracks or fissures often develop. due to more rapid motion of the central part of a valley glacier, stresses and strains are set up and crevasses are formed, usually pointing obliquely upstream. where the ice tends to spread laterally in a broad portion of a valley, longitudinal cracks may develop. crevasses vary in size up to several feet in width and hundreds of feet in depth. owing to the forward motion of the ice, old fissures tend to close up and new ones form, and, aided by uneven melting, the surface of a glacier is generally very rough. like running water, ice may have considerable erosive power when it is properly supplied with tools. the total erosive effect which has been, and is now being, accomplished by ice compared with that of running water is, however, slight. one of the main processes by which ice erosion is accomplished is "corrasion" due to the rubbing or grinding action of hard rock fragments frozen into the bottom and sides of the glacier. thick ice, shod with hard rock fragments and flowing through a deep, narrow valley of soft rock, is especially powerful as an erosive agent because the abrasive tools are supplied; the work to be done is easy; and the deep ice causes great pressure on the bottom and lower sides of the valley. rock surfaces which have been thus subjected to ice erosion are characteristically smoothed and more or less scratched, striated, or ground due to the corrosive effects of small and large rock fragments. this affords one of the best means of proving the former presence of a glacier over a region or in a valley. a typical v-shaped stream cut (eroded) valley is changed into one with a u-shaped profile or cross section by glacier erosion (plate ). another important process of ice erosion is "plucking," which consists in pushing among already more or less loosened joint blocks by the pressure of the moving ice. the pressure thus exerted, especially by a deep valley glacier, may be enormous. this process was an important factor in the development of the famous yosemite valley, a very brief account of whose history it will now be instructive to give. [illustration: plate .--the gorge of niagara river below the great falls. the strata (containing fossils) were accumulated on the bottom of the silurian sea which overspread the region at least , , years ago. since the ice age or within , to , years, the river has carved out the gorge. (_courtesy of the haines photo company, conneaut, ohio._)] [illustration: plate .--(_a_) a winding stream in the st. lawrence valley of new york. due to its low velocity the stream cuts its channel down very little, but it swings or "meanders" slowly from one side of its valley to the other, developing a wide flood plain. the stream once flowed against the valley wall shown at the middle left. (_photo by the author._)] [illustration: plate .--(_b_) davidson glacier, alaska. this glacier is at work slowly grinding down the valley floor and cutting back its walls, thus changing the original stream-cut, v-shaped profile, like that of plate . (_photo by wright, u. s. geological survey._)] the yosemite valley, about miles long, less than one mile wide, and from , to , feet deep, lies on the western slope of the sierra nevada mountains of california. great cliffs of granite, mostly from , to over , feet high, bound the valley on either side. the floor of the valley is wide and remarkably flat (plate ). just prior to the ice age, by the processes of erosion already set forth, the merced river had carved out a great steep-sided v-shaped canyon commonly from , to , feet deep. during the ice age, two glaciers joined to form an extra deep powerful glacier, which flowed through a deep part of the merced canyon and modified it into the yosemite valley, essentially as we see it to-day. because the ice was shod with many fragments of hard rock (granite), and the pressure at the bottom and lower sides of the glacier (several thousand feet thick) was so great, the v-shaped stream-cut canyon was changed to a u-shaped canyon with very steep to even vertical walls. a factor of great importance which notably aided the erosive power of the glacier in this case was the existence of an unusual number of large vertical joint cracks in the granite in this local region. the plucking action of the ice was thus very greatly facilitated and great slabs of rock, separated by the vertical joints, especially toward the lower sides and bottom of the valley, were pushed away one after another by the ice. when the ice disappeared, great precipitous joint faces from , to , feet high were left along the valley sides. at its lower end the glacier left a dam of glacial débris (moraine) across the valley, thus causing a lake to form over the valley floor. the wide flat bottom of the valley was caused by filling up of the lake with sediment. the uniqueness of the yosemite valley is, then, due to a remarkable combination of several main factors; one, the presence of a large swift river well supplied with tools which carved out a deep v-shaped canyon; two, a mighty glacier which plowed its way through this canyon and converted it by erosion into a u-shaped canyon; three, the weakening of the rock by many joint cracks, thus greatly facilitating the ice erosion; and four, a postglacial lake covering the valley floor which became filled with sediment. as a result of the ice work, several streams, tributary to the main stream (merced river) which flows through the bottom of the valley, were forced to plunge over great vertical rock walls (joint faces), thus producing high and beautiful true waterfalls, including the very high upper yosemite fall where yosemite creek makes a straight drop of , feet. a tributary valley like that of yosemite creek, which ends abruptly well above the main valley, is known as a "hanging" valley. the valley of bridal veil creek is another good example. (see plate .) valleys which were once occupied by active glaciers are generally characterized by their u-shaped cross sections and their hanging (tributary) valleys, but the great height and steepness of the valley walls in yosemite are exceptional. a type of glacial erosion which is of special interest is the sculpturing of so-called "cirques" or "amphitheaters" in mountains within the region of perpetual snow. where the main mass of snow and ice in the catchment basin or gathering ground of a valley glacier pulls away from the snow and névé on the upper slopes, the rock wall is more or less exposed in the deep crevasse. during warm days water fills the joint cracks in the rocks down in this crevasse (so-called "bergschrund"), and during cold nights the water freezes and forces the blocks of rock apart. this is greatest toward the bottom of the crevasse and so, by this excavating or quarrying process, vertical or very steep walls are developed around a great bowlike basin or cirque. such cirques, now free from glacial ice, with precipitous walls to , feet high and one-fourth of a mile to one-half of a mile across, are common in the sierra nevada and cascade ranges and in the rocky mountains. what becomes of the materials eroded by the ice? an answer to this question involves at least a brief discussion of the deposition of glacial débris, this constituting an important feature of the work of ice. the débris transported by a glacier is carried either on its surface or within it, or pushed along under it. it is generally heterogeneous material ranging from the finest clay through sand and gravel, to bowlders of many tons' weight. various types of glacial deposits are abundantly illustrated by débris left strewn over much of the northeastern united states and some reference to these will be made. most valley glaciers carry considerable débris on their surfaces, this representing material which falls or is carried down from the valley walls upon the margins of the ice, thus forming marginal moraines. when two glaciers flow together, one marginal moraine from each will coalesce to form a medial moraine. the material carried along at the bottom of a glacier is called the ground moraine. where it contains much very fine grained material with pebbles or bowlders scattered through its mass, it is called "till" or "bowlder clay." the pebbles or bowlders of the ground moraine are commonly facetted and striated as a result of having been rubbed against the bedrock on which the glacier moved. ground moraine material is the most extensively developed of all glacial deposits. it is so widely scattered over the glaciated northeastern portion of the united states that most of the soils consist of it, having been left strewn over the country during the melting of the vast ice sheet. when a glacier remains practically stationary for some time, more or less material which it carries is piled up at its lower end to form a terminal moraine. repeated pauses during general glacier retreat permit the accumulations of so-called recessional moraines. a wonderful display of recessional moraines occurs from the great lakes south, where they are festooned one within another and remain almost exactly as they were formed during pauses in retreat of great lobes of ice during the closing stages of the ice age. a great terminal moraine marks the southernmost limit of the ice sheet during the ice age, a very fine illustration being the ridge of low irregular hills extending the whole length of long island. some of the material in that morainic ridge was transported by the ice from northern new england. considerable rock débris is transported within the ice, and such "englacial" material in part results from rock débris which falls on the surface in the catchment basin and becomes buried under new snowfalls which change to ice, and in part from material which falls into the crevasses in the glacier farther down the valley. marked objects thrown into the catchment basin have, after many years, emerged at or near the end of the glacier; thus the rate of motion can be very accurately told. a very remarkable case of transportation through the body of a glacier is the following: in , three men were buried under an avalanche in the catchment basin of the bossons glacier in the alps. forty-one years later several parts of the bodies, including the three heads together with some pieces of clothing, emerged at the foot of the glacier after traveling most of its length at the rate of eight inches per day. the heads were so perfectly preserved after their remarkable journey in cold storage that they were clearly recognized by former friends! where a valley floor slopes downward away from the end of a glacier, waters emerging from the ice, heavily loaded with rock débris, cause more or less deposition of the débris on the valley floor often for miles beyond the ice front. such a deposit is called a "valley train." when the ice front pauses for a considerable time upon a rather flat surface, the débris-laden waters emerging from the ice develop an "outwash plain" by deposition of sediment rather uniformly over the flat surface. a very fine example is the plain which constitutes most of the southern half of long island just beyond the southern limit of the great terminal moraine ridge. a type of glacial deposit of particular interest is the "drumlin" which is, in reality, only a special form of ground moraine material (commonly till), and, therefore, essentially unstratified. typical drumlins are low, rounded mounds of till with roughly elliptical bases and steeper fronts facing the direction from which the ice flowed. their long axes are always parallel to the direction of ice movement. in height they commonly range from to feet. their mode of origin is not yet definitely known, but they form near the margins of broad lobes of ice either by erosion of earlier glacial deposits, or by accumulation beneath the ice under peculiarly favorable conditions, as perhaps in the longitudinal crevasses. one of the finest and most extensive exhibitions of drumlins in the world is in western new york between syracuse and rochester. thousands of drumlins there rise above the general level of the ontario plain, the new york central railroad passing through the very midst of them. drumlins are also abundant in eastern wisconsin. another type of glacial deposit in the form of low hills is the "kame" which, unlike the drumlin, always consists of more or less stratified material. kames are seldom over feet high, and they are of various shapes. in many cases they form irregular groups of hills, and in other cases fairly well defined kame ridges. kames form as deposits from débris-laden streams emerging from the margins of glaciers, the water sometimes rising as great fountains because of the pressure. such deposits are now actually in process of formation along the edge of the great malaspina glacier of alaska. kames are commonly associated with terminal and recessional moraines. "eskers" are similar except that they are long winding low ridges of stratified material deposited by débris-laden streams, probably in longitudinal fissures in the ice near its margin. (see plate .) glacial bowlders, or "erratics" are blocks of rock or bowlders left strewn over the country during the melting of the ice. they vary in size from small pebbles to those of many tons of weight, and most of them were derived from ledges of relatively hard, resistant rocks. (see plate .) erratics have very commonly been carried a few miles from their parent ledges, while more rarely they have traveled even hundreds of miles. they are extremely abundant in new york and new england, many occurring even high up on the mountains. in some cases erratics of ten or more tons' weight have been left in such remarkably balanced positions on bedrock that a child can cause one of them to swing back and forth slightly. such a bowlder is literally a "rocking stone." in the adirondack mountains the writer recently observed a rounded erratic of very hard rock fourteen feet in diameter resting in a very remarkably balanced position on top of another large round glacial bowlder. chapter vi the action of wind only during the last quarter of a century have geologists come to properly appreciate the really important geological work of the wind. one reason for this is the fact that people live mostly in humid regions where the soils are largely effectually protected against wind action by the vegetation. but even in such regions, wind action is by no means negligible. one has but to observe the great clouds of dust raised by strong wind from freshly cultivated fields during a little dry weather in the late spring. much of this dust is carried considerable distances, often miles, and in some cases young crops are injured by removal of soil from around the roots, while in other cases young plants are buried by deposition of the wind-blown material over them. in humid regions, the action of the wind is perhaps most strikingly exhibited along and near shores of sea and lakes, where loose dry sands are picked up and transported in great quantities, often depositing them as sand dunes, which may form groups of hills covering considerable areas. very conspicuous examples are the sand dunes of dune park in northern indiana, and the dunes along the coast of new jersey. but the action of wind is most strikingly effective in desert and semiarid regions. the importance of the work of wind is made more impressive when we realize that about one-fifth of the land of the earth is desert. in deserts some of the ordinary agents of weathering and erosion are either absent or notably reduced in effectiveness. thus, stream action is, in general, reduced to a minimum; weathering effects due to moisture in the air are notably reduced, and either frost action, or wedge work of ice, is relatively unimportant due to lack of water. change of temperature between night and day is, however, unusually important as a process whereby rocks are broken up due to relatively rapid expansion and contraction in deserts because such temperature changes are exceptionally great, and rocks and soils are almost everywhere directly exposed, being free from vegetation. the finer grained materials, especially sand grains, in deserts are picked up by the wind and driven, often with great velocity, against barren rock ledges and large and small rock fragments. by this process (corrasion) the rocks are worn and often polished by the materials blown against them. the principle is that of the artificial sand-blast, used in etching glass, or cleaning and polishing building and decorative stones. under favorable conditions wind-driven sand accomplishes noticeable erosion in a surprisingly short time. thus, in a hard wind storm, a plate glass window in a lighthouse on cape cod was worn to opaqueness, while in a few weeks or months the directly exposed window glass may there be worn through. the great erosive effect of wind-driven sand is relatively close to the ground because the larger and heavier fragments are not lifted to very considerable heights. for this reason ordinary telegraph poles are difficult to maintain in desert regions because, unless they are specially protected, they are soon cut down by sand swept against their bases. in the desert regions of our southwestern states cliffs rising above the general level of the country are often undercut by wind erosion, sometimes with the development of large caverns. (see plate .) even the high portions of great ledges are there more or less fantastically sculptured by wind erosion, the softer portions being more deeply cut into than the harder. the famous sphinx of egypt has been notably roughened by action of this kind. the enormous power of high winds to transport rock material in desert regions is strikingly illustrated by the great sand storms of the sahara desert, where sand and dust, forming clouds with cubic miles of volume, sweep for many miles across the country. some one has estimated that every cubic mile of air in such a storm contains more than , tons of rock material. it is said that an army of , men under cambyses was buried under the sands of a storm in the desert of northern africa. dust from some of these storms is known to be driven hundreds of miles out over the atlantic ocean, there to settle in the sea. in mountainous desert regions, like the great basin of our western states, the general tendency is for the rock materials wind-eroded from the mountains to be carried into the intermontane basins or valleys. some basins of this sort are believed to contain depths of , to , feet of wind-blown material. a special kind of wind-blown material called "loess," is a sort of fine-grained yellow, or brown loam which, though relatively unconsolidated, has a remarkable property of standing out as high steep cliffs or bluffs along the banks of streams. many thousands of square miles of northern china are covered with loess. among many other regions, thousands of square miles of parts of the states of iowa, nebraska, and kansas are covered with loess, which, in this case, is believed to be fine material gathered by winds from the region just after the retreat of one of the ice sheets of the great ice age, when there was very little vegetation to hold down the loose soils of glacial origin. much as snowdrifts are formed, so, in many places, the wind-driven sands are built up into sand hills or so-called "dunes." dunes are very common in many places, as for example, along our middle atlantic coast; in dune park of northern indiana; and in the great arid and semiarid regions of the western states. where there is a distinctly prevailing direction of wind, the sand is blown to the leeward side from the windward side, and the dunes are caused to migrate in the direction of the wind. the burial and destruction of forests, and the uncovering of the dead trees is not uncommonly caused by migration of sand dunes, all stages of this phenomenon being well exhibited in dune park, indiana. the rate of dune migration is very variable, but study in a number of places has shown a rate of from a few feet to more than feet per year. arable lands, buildings, and even towns have been encroached upon and buried under drifting sand. an interesting example is a church in the village of kunzen, on the baltic seashore which, in a period of sixty years, became completely buried under a dune and then completely uncovered by migration of the dune. much destruction has been wrought by shifting sands on the bay of biscay, where farms and even villages have been overwhelmed. the ruins of the ancient cities of babylon and nineveh are buried mostly under wind-blown sand and dust. there is good reason to believe that the climate of central and western asia is now notably drier than it was a few thousand years ago, and this may help to explain the burial of many old cities and villages there under wind-blown deposits. chapter vii instability of the earth's crust the crust of the earth is unstable. to the modern student of geology the old notion of a "terra firma" is outworn. the idea of an unshakable, immovable earth could never have emanated from the inhabitants of an earthquake country. in general we may recognize two types of crustal movements--slow and sudden. to most people the sudden movements accompanied by earthquakes are more significant and impressive because they are more localized and evident, and often accompanied by destruction of property, or quick, though minor, changes in the landscape. but movements which take place slowly and quietly are often of far greater significance in the interpretation of the profound physical changes which have affected the earth during its millions of years of known history. [illustration: fig. .--structure section across the hudson river valley near west point, new york. the shafts and tunnel, , feet below sea level, in solid rock, show the position of the new york city aqueduct from the catskills. the preglacial valley has been submerged and filled with postglacial sediment to a depth of nearly feet. (redrawn by the author after berkey, from new york state museum bulletin.)] a few well-known examples will serve to prove that upward, downward, and differential movements of the earth's crust have actually taken place not only in the remote ages of geologic time, but also that such movements have geologically recently taken place, and that similar movements are still going on. it is very important that the reader thoroughly appreciate the fact that crustal disturbances, often profound ones, do take place, because this is one of the most fundamental tenets of geologic science. let us consider the case of the hudson-champlain-st. lawrence valley region. that the whole region was once notably higher (at least , feet) than at present is proved by the drowned character of the hudson valley, in which tidewater extends northward for miles to near troy. where the new york city aqueduct passes under the hudson river near newburgh, the bedrock bottom of the old river channel is now about feet below sea level as determined by drilling. this old channel is there filled up nearly to sea level with glacial and postglacial rock débris, which shows that the old channel must have been cut before the oncoming of the ice of the great ice age. before the ice age, then, the lower hudson valley must have been considerably more than feet higher than at present, because it then contained a river with sufficient current to be an active agent of erosion, carving out the canyonlike valley in the vicinity of west point. this conclusion is strongly reenforced by the fact that the old valley of the hudson river has been definitely traced as a distinct trench across the shallow sea bottom for about miles eastward from the entrance to new york harbor. toward the eastern end of this trench the depth of water is now considerably over , feet, and thus it is obvious that, preceding the ice age, the earth's crust in the vicinity of new york city must have been much higher than at present, so that the hudson river was able to erode its now completely drowned channel. somewhat similar evidence has also established the fact that the lower st. lawrence valley region was much higher before the ice age. it is evident, therefore, that the general hudson-st. lawrence valley region is now notably lower with reference to sea level than it was before the ice age. that this was caused by actual sinking of the earth's crust rather than by a rise of sea level is proved by the fact that similar changes of level between land and sea did not take place at the same time even along the atlantic and gulf coast of our southern states. we shall now proceed to the next step in the geologically recent history of earth-crust movements in the hudson-champlain-st. lawrence valley region by asserting that, since the ice age, the land was actually notably lower than at present. in fact, the land was enough lower to allow tidewater to extend up the st. lawrence valley into the ontario basin, and all through the champlain-hudson valley. many beaches, bars, and delta deposits formed in these arms of the sea are still plainly preserved, in some cases with shells and bones of marine animals in them, now hundreds of feet above sea level. these marine deposits are highest above sea level in the northern portion of the champlain valley, where they lie at an altitude of feet or more and their altitude steadily diminishes southward to about to feet in the general vicinity of albany, and to near sea level in the general vicinity of new york city. obviously, then, the land stood lower during part or all of the interval of not more than a few tens of thousands of years since the ice age than at present. this leads us to the third important conclusion regarding earth movements in this region, namely, that still later the land has undergone a differential uplift, the rate having steadily increased toward the north where the total uplift is many hundreds of feet. we have discussed this region somewhat in detail because the principles of slow up and down movements of the earth's crust are there so plainly recorded. among many other regions where earth movements similar to those above described have taken place, brief mention may be made of norway. the great fjords of norway were, just before the ice age, stream-cut valleys which were then more or less modified by glacial erosion, and after the ice age the rivers in them were drowned due to land subsidence. the kind of evidence is like that above given for the lower hudson river. since the subsidence there has been partial reelevation, as proved by the fact that along the sides of the larger fjords marine terraces and beaches may be traced with gradually increasing altitude for many miles ( or more) back into the country where they are hundreds of feet above tidewater. scandinavia is of still further special interest because very appreciable earth movements have there come under human observation. marks carefully placed along the shores of sweden by the government have proved that during the last years the southern end of the country has actually subsided several feet, while from stockholm north the land has risen in increasing amount, reaching a maximum of seven or eight feet. in southern sweden, at malmo, a certain street now at times becomes covered by wind-driven high water, and during excavations made some years ago an older street eight feet below the present one was found. a theory which appears to be in perfect harmony with the facts to account for the subsidence and partial reelevation of central eastern north america and scandinavia since the beginning of the ice age is that the great weight of ice during the ice age pressed the land down, and that since the removal of the ice there has been an appreciable tendency for the land to spring back. certain crustal movements which have occurred about the bay of naples are of very special interest because actual human history dates can be placed upon them. most remarkable are the records in connection with the temple of jupiter serapis which was built near the shore before the christian era. the land sank about five feet and a new pavement had to be constructed; then, by the middle of the third century a. d., the temple rose to well above sea level. by about the ninth century the land had subsided fully thirty feet, so that marble columns of the temple were bored full of holes as high as twenty-one feet above their bases by marine-shelled animals, species of which still live in the bay. then a slow uplift of twenty-three feet began, bringing the bases of the columns two feet above sea level by . since that time a slight sinking has taken place and this seems to be still going on. three of the marble columns with the borings still stand in upright position. while the movements just described were taking place, the island of capri, twenty miles across the bay of naples, has slowly sunk to an amount estimated at thirty or forty feet as proved by evidence from the famous blue grotto. about the beginning of the christian era a large ancient wave-cut cave, part of which is now called the blue grotto, had its floor above sea level, and it was used by certain romans as a cool place to retire to from the heat. in order to obtain better light an opening was cut through its upper portion. the land has sunk so much that at the present time even part of the artificial opening (through which tourists pass) is now under water. by way of illustrating remarkable contrasts in direction of crustal movements on very considerable scales in a given region, we shall briefly mention some facts regarding part of the coast of southern california and the neighboring islands of santa catalina and san clemente, respectively twenty-five and fifty miles offshore. those movements were not, however, checked up by human history records. the mainland at san pedro has clearly risen , feet, as proved by the presence of unusually perfect coast terraces (so-called "raised beaches"), while san clemente has risen , feet as proved by the raised beaches into which deep, youthful v-shaped stream-cut valleys have been sunk, and a shore line characteristic of recent notable uplift. it is a remarkable fact that at the same time the intervening island (santa catalina) has notably sunk, as proved by the nature of its shore line, and the distinctly more mature character of its topography. we are, however, by no means dependent upon lands along sea shores for evidences of slow rising and sinking of land. thus, by careful measurements it has been shown that the general region of the great lakes is now differentially rising toward the northeast at the rate of about five inches per miles per century. at chicago the rise of water is estimated at about nine inches per century, which means increase of flowage through the chicago canal. at this rate the upper lakes would, in some thousands of years, drain through this canal to the mississippi. a well-preserved shore line of the large ancestor of lake ontario shows a steady increase in altitude at the rate of several feet per mile toward the northeast from near niagara to the st. lawrence valley, thus proving a tilting of the land since the shore line was formed. shore lines of the great ancestor of great salt lake also show warping of the earth's crust, some parts of a definite shore line being several hundred feet higher than others. very significant evidence pointing to profound crustal movements consist in the finding of fossil remains of marine animals in the strata high above sea level, very commonly from one to three miles, in many parts of the world, especially in the high mountains. in wyoming, nearly horizontal strata of the mesozoic age carrying marine fossils lie two miles or more above sea level. the fact that given formations, carrying marine fossils representing certain definite portions of geologic time, are found at various altitudes up to several miles in many parts of the world, shows that the land in those places has really risen relative to sea level. it should not be presumed from the above discussion that the sea level itself has never changed. thus, the vast areas of thick ice sheets in both north america and europe during the great ice age represented sufficient water withdrawn from the sea to very appreciably lower its level. all land-derived materials, carried into the sea mainly by rivers, displace sea water, with consequent rise of its level. if all existing lands were worn down and carried into the sea, its level would be raised some hundreds of feet. subsidence of any part of the ocean bottom would cause a lowering of sea level. there is a strong reason to believe that some such shiftings of sea level have occurred during the vast lapse of geologic time. during certain periods erosion of the land predominated, and during other periods building up of the land predominated, as pointed out in the chapters on geologic history. it is not thought that shifting of sea level has ever amounted to more than a few hundred feet, at least not during the millions of years of the more clearly recorded earth history. we have thus far considered slow upward and downward movements of the earth's crust without notable structural changes in the rocks. another type of crustal disturbance causes more or less profound changes in the structures of the rocks themselves. just how the earth originated is a matter of uncertainty, but we can be sure that for many millions of years it has been a shrinking body. the outer, or crustal, portion of the earth, in adjusting itself to the contracting interior, has had many pressures, stresses, and strains set up within it. as results of such forces the rocks at and near the earth's surface have in various places, and at various times, been broken (faulted) and subjected to sudden movements (see discussion beyond), while those well within the crustal portion, that is to say a few miles or more down, have, in many cases, been bent (folded), or even crumpled. for these reasons the surface and near-surface crustal portions are called the "zone of fracture," while the more deeply buried portions comprise the "zone of flowage." in the zone of flowage the rocks, where subjected to great lateral pressure, act like plastic materials and therefore bend rather than break, because of the great weight of overlying materials. laboratory experiments have confirmed the findings of geologists in this regard. small masses of rocks properly inclosed in nickel-steel cylinders have been subjected to slow differential pressures equivalent to those which obtain twenty to forty miles within the earth. under such conditions rocks have been made to change shape very notably without fracturing. both geological observations and experiments have led us to conclude that not even small fractures or crevices can remain open at a depth greater than ten or twelve miles even in the hardest rocks. from time to time, during the long history of the earth, forces of lateral pressure have been slowly exerted along more or less localized zones or belts within the earth's crust, and the rocks have been deformed chiefly by bending or folding, especially in those regions where mountains of the folded type have developed. movements of this type are considered beyond in the chapter on mountains. rock folds vary in size from microscopic to miles across, and they exhibit many shapes. plate will give the reader a good idea of actual rock folds of common sizes and shapes in various places. folded structures are most clearly discernible in sedimentary rocks, because of their stratified (layered) arrangement. since folds in hard rocks rarely, if ever, develop except at a depth of some miles within the earth, they show at the surface only where great thicknesses of overlying materials have been stripped off by erosion. [illustration: fig. .--an outcrop of stratified crystalline limestone (or marble) exhibiting two small sharp folds--a syncline on the left and an anticline on the right--near lenox, mass, these folds developed during the great mountain-making disturbance at the end of the ordovician period fully , , years ago. (after dale, u. s. geological survey.)] from the standpoint of our consideration of slow earth-crust movements, it is important to bear in mind that lateral pressure in the zone of flowage has not only notably deformed rocks, but that, as a result of the buckling forces, given rock masses have, in many cases, been notably shifted downward or upward--mainly upward--from their original positions. folded strata carrying shells of sea animals are commonly found thousands of feet above sea level in many of the great mountain ranges of the world. during the process of folding on a large scale the crust of the earth is very appreciably shortened at right angles to the direction of applied pressure, due to squeezing or bending of the strata. in the case of the appalachian mountains of pennsylvania it has been estimated that such shortening amounts to about twenty-six miles or, in other words, that the strata originally spread out horizontally across an area whose width was about miles have been squeezed or folded into an area whose width is twenty-six miles less. [illustration: fig. .--structure section showing the profile of the mountains and relations of rocks below the surface near livingston, montana. the strata were crowded together until they bent into great sharply defined folds at the time of the rocky mountain revolution several million years ago. then the rocks broke along the fault fracture and the mass on the right was shoved over upon the mass on the left. (after u. s. geological survey.)] we shall now turn to a consideration of sudden earth movements and some of their effects, including earthquakes. mention has already been made of the fact that, when pressures and strains are set up in the outer portion ("zone of fracture") of the earth's crust, the rocks yield mainly by breaking or fracturing because the rocks not being under a great load of overlying material are there brittle. the earth's crust has been fractured on small and large scales in many places during the long space of geologic time. where one block of earth's crust has slipped or moved past another along a fracture we have what is called a "fault." such displacements of rock masses vary in amount from less than an inch to some miles, and they constitute one of the most important features of the architecture of the outer portion of the earth. there are two types of faults fundamentally different as to cause. in one type (so-called "normal fault") the rocks suddenly yield to a force of tension; a fracture develops and the earth block on one side of the fracture or fault drops with reference to that on the other. in the other type (so-called "thrust faults") the rocks yield suddenly to a force of compression or lateral thrust, and one block of earth is pushed or thrust partly over another along the surface of fracture or fault. (see plate .) faults range in length up to hundreds of miles, those from one to twenty miles in length being very common. where an earth block has been displaced thousands of feet along a fault surface, it is not to be understood that the whole displacement resulted from a single movement, but rather from a series of sudden movements separated by greater or less intervals of time. each sudden movement along a fault surface produces a vibration of the earth near by. many such sudden movements are known to have caused violent earthquakes. displacements of twenty to fifty feet, as a result of single movements, are definitely known to have taken place in various regions during the last fifty years; and rarely, if ever, has any sudden displacement of as much as several hundred feet occurred. cliffs and steep slopes very commonly result from faulting, but, because of the long lapse of time required for the repeated movements in the case of great faults, the cliffs or steep slopes begin to wear back and become more or less subdued long before the last of the movements take place. in regions where movements along great faults have long since ceased, the original steep slopes may be completely obliterated by erosion. [illustration: fig. .--vertical sections through strata illustrating common kinds of faults: a, "normal faults" where one mass simply sinks below another; b, a "thrust fault" where one mass is shoved over another. (after u. s. geological survey.)] how does the geologist determine the actual amount of displacement, especially in the case of a large fault in stratified rocks? first, the various formations of the region, where unaffected by faulting, are carefully studied, especially in regard to the character and thickness of each, and their relative geologic ages or normal order as they were deposited one layer above the other. then, in the simple case of a normal-fault surface at right angles to horizontal strata, it is only necessary to find out what two formations or parts of formations come together along the fault fracture, and the actual amount of displacement is readily determined. where strata and normal fault surfaces lie at various angles, and also in thrust faults, those angles must be determined in addition to the data above named. in many mining regions, where valuable deposits are affected by faulting, accurate knowledge of the direction and amount of displacements of faults is of great economic importance. a few examples of normal faults from well-known districts will now be briefly described. the whole eastern front of the central and southern sierra nevada range of california is a great, steep fault slope, from a few thousand to ten thousand or more feet high and hundreds of miles long, of such recent geologic age that it has been only moderately affected by erosion. in fact, it is well known that the southern two-thirds of the range is a great tilted fault block, the total displacement having resulted from repeated sudden movements since about the middle of the present geologic era. a great fault also extends along the eastern base of the great wasatch range of utah and the steep slope thousands of feet high is a fault scarp only slightly modified by erosion. renewed movements along this profound fault have very recently taken place as proved by the presence of fresh fault scarps in loose deposits which have accumulated across the mouths of some of the canyons, as, for example, near ogden. in fact, practically all of the north-south ranges of the great basin from utah to california are essentially a series of tilted fault blocks. another great fault, less conspicuous from the topographic standpoint, is hundreds of miles long in the coast range mountains of california. at the time of the san francisco earthquake of there was a renewed sudden movement along this great fracture. the eastern one-half of the adirondack mountains of new york is literally a mosaic of hundreds of fault blocks. many of these faults are from two to thirty miles long and they commonly show displacements of from a few hundred to , or more feet. a glance at the geological map (in colors) of the vicinity of the great copper mines at bisbee, arizona, shows most of that region to contain a network of normal faults which separate it into a mosaic of fault blocks. in each of the examples of faults just given a block of earth has sunk relative to the other, or in other words, each is a "normal fault." we shall now turn to some large scale cases of faults in which great masses of earth have been pushed one over another--so-called "thrust faults." in the southern appalachian range, and especially well exhibited in the vicinity of rome, georgia, one portion of the mountain mass has literally been shoved over another, at a low angle over a fault surface many miles long, for fully seven miles westward. both the tremendous weight of rock material actually translated and the number of sudden movements required in the operation stagger the imagination. it is safe to say that during the long time of this great operation violent earthquakes were not uncommon. in the rocky mountains of the northern united states and southern canada there is the greatest known thrust fault on the continent. it is hundreds of miles long, and the actual displacement is commonly at least several miles. in the glacier national park of montana it has been established that the front range portion of the rockies has actually been pushed at least seven miles, and possibly as much as twenty miles, eastward over a fault surface, and out upon the great plains. in some cases rocks of the prepaleozoic age have there been pushed upon rocks of the late mesozoic age, thus locally upsetting the geologic column. [illustration: fig. .--east-west profile and vertical structure sections fifty-two miles long in the mohawk valley region of new york, showing numerous tilted fault blocks which notably influence the topography. vertical scale exaggerated. the rocks are prepaleozoic and early paleozoic in age. (modified by the author after darton, new york state museum.)] the wasatch range of utah, in addition to the great normal fault along its western base, contains a remarkable system of thrust faults. in the region now occupied by the wasatch mountains a number of parallel (thrust) faults were developed close together and the broken pieces of the earth's crust between them were pushed up, the rocks on one side of each crack riding up over those on the other side until a great mountain range was formed where once lay a plain. in the ogden canyon one great earth block of prepaleozoic (algonkian) age has been shoved thousands of feet over late paleozoic (carboniferous) rock, which latter has in turn been thrust over early paleozoic (cambrian) rock. this thrust faulting was accomplished before the development of the geologically recent normal fault along the western base of the range. [illustration: fig. .--vertical (structure) section through a part of the earth's crust several miles long in ogden canyon, utah, showing the system of great thrust faults. prepaleozoic (algonkian) rocks have been pushed far over upon late paleozoic (carboniferous) strata, which latter have in turn been shoved over early paleozoic (cambrian) strata, etc. (after u. s. geological survey.)] any sudden movement of part of the crust of the earth, due to a natural cause, produces a trembling or shaking called an earthquake. though earthquakes are generally classed among the most terrifying of all natural phenomena, those which have occurred during human historic times have had scarcely any geological or topographical effects of real consequence on the face of the earth. locally, the effects may be notable and the destruction of life and property may be great. the earth may be locally cracked and rent, small fault scarps may develop, landslides and avalanches may result from the shaking of the earth, buildings may be demolished, and sea waves may be rolled upon the land. on the other hand, many earthquakes, called "tremors," are too slight to be noticed by people, though they are recorded by specially constructed instruments called "seismographs." we have already stated that actual sudden displacements causing earthquakes have amounted to twenty or even fifty feet right along fault fractures, but during the vibrations or quakings, which are often so destructively sent out into the neighboring country, the earth's surface rarely actually moves more than a small fraction of an inch. because of the suddenness of the movement objects on the surface may be moved inches or even feet. violent shocks may last one or two minutes and cause the whole earth to tremble, though at distant points only seismographs record the movement. it is probably true that some part of the earth is shaking all the time. studies during the last fifty years have made it certain that the main cause of earthquakes is the sudden slipping of earth blocks past each other along fault fractures, the sudden slipping furnishing the impulse which sends out the vibrations into the surrounding more or less elastic crust of the earth. the low rumbling to roaring sound, which sometimes immediately precedes an earthquake, is probably due to the grinding of the rocks together below the surface. earthquakes generally accompany volcanic outbursts of the violent or explosive type, and in such cases subterranean explosions cause both the eruptions and the quakings of the earth. it is well known that the principal volcanic districts or belts of the earth are also the belts of most frequent earthquakes, but this does not mean that volcanic action causes most of the earthquakes. active volcanoes and earthquakes are so commonly associated in the same belts because those belts no doubt represent portions of the crust which are now most actively yielding to the forces directly resulting from the shrinkage of the earth. within the volcanic belts many earthquakes take place unaccompanied by any volcanic action, and many others take place far from volcanoes. some earthquakes have been caused by the impact of great landslides or avalanches, or by the sudden caving in of underground openings. brief descriptions of a few typical carefully studied earthquakes during recent years will serve to make the main features of earthquakes still clearer to the reader. the violent japanese earthquake of was caused by the sinking of a block of earth forty miles long from two to thirty feet below that on the other side of a fault fracture. there was also considerable horizontal shifting, and cracks developed in the adjacent region. a distinct fault scarp, fifteen to twenty feet high, developed, and in some cases extended right across cultivated fields. [illustration: fig. .--map of the united states, showing the large areas over which three of the greatest of our earthquakes were actually felt by people. these earthquakes were recorded in many parts of the world by delicate instruments: new madrid, ; charleston, ; san francisco, .] [illustration: fig. .--sketch map showing the trace of the great fault fracture along which a renewed sudden movement of as much as twenty feet took place to cause the san francisco earthquake of . (after u. s. geological survey.)] the san francisco earthquake of was produced by renewed movement along the great fault which extends lengthwise through the coast range mountains for several hundred miles. it is literally correct to say that, for miles along this great earth fracture, one part of the coast range instantaneously slipped from two to twenty-two feet past the other. more or less of the movement extended at least several thousand feet down into the earth. in this case both sides slipped and the movement was very largely horizontal rather than vertical. the land on the east side of the fault moved south and that on the west side moved north, the amount diminishing away from the fault on each side so that some miles out the actual crustal movement was only a few inches. when one thinks of the tremendous volumes of earth material involved in this shifting of the earth's crust, is it any wonder that such destructive earthquake waves were produced? many buildings were wrecked, several hundred people were killed, the disastrous san francisco fire resulted, water mains were broken, and fences and roads crossed by the fault were dislocated as much as fifteen to twenty feet. [illustration: plate .--swift current valley in glacier national park, montana. this was once a deep v-shaped canyon carved out (eroded) by stream action. then a great valley glacier slowly plowed its way through it during the ice age and, by ice erosion, the present nearly straight u-shaped canyon has resulted. (_photo by campbell, u. s. geological survey._)] [illustration: plate .--view in the yosemite valley from near the western entrance. the great rock called "el capitan," on the left rises , feet above the river, and bridal veil falls on the right is feet high. all the rock is granite, the nearly vertical walls of which have resulted from the action of a great glacier which plowed its way through the valley during the ice age; the valley walls have been cut back by the removal of large vertical joint blocks. the flat bottom of the valley has resulted from the filling with sediment of a postglacial lake in the valley. (_photo by f. n. kneeland, northampton, mass._)] during the great earthquake on the coast of alaska in notable changes took place along the shore for some miles, one portion having suddenly risen as much as forty-seven feet, while another portion sank below sea level. [illustration: fig. .--map showing the principal earthquake regions of the world.] in the earthquake centering near charleston, s. c., was preceded by rumbling and roaring noises and the slight quaking increased to violent shaking which lasted more than a minute. eight minutes later a rather violent earthquake shock took place, followed during the next ten or twelve hours by less severe shocks. most buildings in the city were wrecked or more or less badly damaged, and some people were killed. the shocks were so violent that the quaking was actually felt by people over an area of more than , , square miles, the disturbance having spread at the rate of about miles per minute. near charleston openings and fissures were formed through which sand and muddy water were ejected, but the cause of the disturbance was most likely slipping of the old very hard rocks below the loose deposits of the coastal plain. from to a series of violent earthquakes developed in the general vicinity of new madrid, missouri. in an area of over , square miles, now called the "sunk country," many portions suddenly sank giving rise to small fault scarps or cliffs, and various lake basins were formed. development of a fissure caused a local change in the course of the mississippi river. in , assam, india, was shaken by an earthquake of unusual magnitude, which lasted - / minutes. an area of , square miles was disastrously shaken, and the shocks were distinctly felt over an area of , square miles. a number of notable fault scarps developed, the movement on one having been thirty-five feet. chapter viii volcanoes and igneous rocks not only because of the great power and terrifying grandeur of violent eruptions, but also because of their destruction of life and property, volcanoes stand out in the popular mind as among the most real and important of all geological phenomena. but great volcanic outbursts, like violent earthquakes, are in truth only outward, sensible, relatively minor manifestations of the tremendous earth-changing forces below the surface. they are far less important as geological agencies than the mighty interior forces which cause parts of continents to be slowly upraised and the rocks folded, or even than the incessant action of streams whereby the lands are cut down. even as an igneous agency, volcanoes are notably less important than the development and shifting of molten materials within the earth's crust. volcanic action is, however, not only conspicuous, but it is also of real significance as a means of changing the earth, such action having taken place since very early known geologic time. after bringing out the main facts and principles of volcanoes, aided by descriptions of specific eruptions, we shall turn to a consideration of igneous activity within the earth's crust. mount vesuvius in italy is perhaps the most famous active volcano in the world. its eruptions have been more or less carefully studied for a longer time than any other. the eruption in the year a. d. was really a tremendous explosion causing a large part of the old crater to be blown away, and sending immense volumes of rock fragments, mostly finely divided (so-called "ashes") into the air which completely buried the small city of pompeii. water from the great clouds of condensing steam, mixed with "ashes," formed muddy floods which overwhelmed herculaneum. little or no lava was erupted. since that time the crater has been more or less active and the present cone, , feet high, has been built up. during the last fifty years the greatest eruptions took place in and , when, streams of molten rock flowed down the sides of the mountain. [illustration: fig. .--map showing the distribution of active and recently active volcanoes of the world.] one of the greatest volcanic explosions ever recorded was that of the island of krakatoa, between sumatra and java, in . the greater part of the island was blown away and there was water , feet deep, where just before the island stood hundreds of feet high. about a cubic mile of rock material was sent into the air mostly in the form of fine dust--some of it for seventeen miles--and completely hid the sun, causing total darkness during the eruption. dust fell over an area of several hundred thousand square miles. several days after the explosion ships more than , miles away were dust covered. such enormous quantities of a light porous lava called "pumice" fell and floated upon the sea that navigation was badly obstructed many miles from the volcano. extremely fine dust gradually spread through the whole earth's atmosphere, causing the extraordinary red sunsets for several months. the sound of the explosion was heard for hundreds of miles. great sea waves to feet high were stirred up and they swept inland for several miles over the low-lying coast lands of neighboring java and sumatra, overwhelming hundreds of villages and drowning tens of thousands of people. [illustration: fig. .--the great hole left after the top of mt. katmai in southern alaska was blown off in by one of the most tremendous volcanic explosions in the annals of human history. the water in the lake is hot. (after griggs, national geographic magazine.)] one of the greatest explosions on record was that of katmai volcano, several thousand feet high, on the coast of alaska, in june, . not only was the top of the mountain completely blown off, but also a great crater pit, three miles wide across the top and several thousand feet deep, was developed in the stump of the former mountain. volcanic dust fell to a depth of several feet within twenty-five to fifty miles of the mountain. dust accumulated to a depth of nearly a foot in the village of kodiak, miles east of the mountain, where total darkness prevailed for more than two days. a lake of very hot water now occupies the bottom of the great new crater. the noise of the explosion was heard for at least miles. [illustration: fig. .--diagrammatic vertical or structure section through a portion of the earth illustrating the common modes of occurrence of igneous rocks. p, deep-seated (plutonic) igneous rock; s, strata; d, dikes; m, mass of igneous rock forced between strata bending them upward; f, feeding channel of volcano; v, volcano; l, lava sheets. (by the author.)] one of the most frightful volcanic catastrophes of recent years was the eruption of mont pelée, island of martinique, west indies, in . in this case, also, no lava was poured out, but violent explosions sent great clouds of very highly heated gases and vapors, mingled with incandescent dust, thousands of feet into the air. one of these great clouds rushed down the mountain at hurricane speed and destroyed the city of st. pierre with its , inhabitants. after the main eruption a spine or core of hard rock began to rise out of the crater and it slowly grew to a height of , feet in several months, after which it began to crumble away. this spine probably represented nearly frozen lava which solidified as it was gradually forced out of the mountain. of special interest to us, though not of great importance is the only active volcano in the united states. in may, , mount lassen (or lassen peak), a long inactive volcano in northern california, suddenly burst forth explosively and during the next several years hundreds of eruptions occurred. little or no lava appeared, but great clouds of steam and dust often shot into the air from one to three miles above the top of the mountain, which lies over , feet above sea level. (plate .) great quantities of dust have accumulated for miles around the mountain. at this writing (october, ) the mountain is again active. it should not be presumed, however, that all, or nearly all, volcanoes are of the explosive type. others of the more quiet type are well exemplified by the two great hawaiian volcanoes, mauna loa and kilauea. any but relatively very minor explosions rarely, if ever, occur, the product of such volcanoes being almost wholly lava, which flows down the mountainsides in molten streams. the hawaiian islands have, in fact, been almost entirely built up by successive eruptions of lava, the building-up process having begun well below sea level. mauna loa rises to nearly , feet above the sea, but, due to the fact that the streams of lava have spread so far, the mountain has an exceptionally low angle of slope which makes it difficult to realize that it is so high. considering its submarine portion, mauna loa really rises nearly , feet above the sea floor. although kilauea lies nearly , feet above sea level on the flank of mauna loa, and only twenty miles distant from it, the two volcanoes are singularly independent in regard to their eruptions. each mountain has a crater irregularly oval in shape, nearly three miles long, bounded by almost vertical walls of hard lava, in some cases arranged in terraces. the floors of the great crater pits are relatively level, and consist of black lava in which are lakes of molten and even boiling lava. the black lava floor is, in each case, only a frozen or hardened crust upon a great column of molten lava extending down into the mountain. prior to an eruption of mauna loa the lava column rises hundreds of feet in the crater, but during recent years the lava seldom, if ever, flows out over the crater rim. instead, it breaks through the mountainsides at various altitudes, the great flow of having started at an altitude of about , feet. this stream of liquid rock, fully one-half of a mile wide, flowed for weeks down the mountainside and into the ocean, the waters of which, in contact with the highly heated lava, were thrown into terrific commotion. in a stream of lava several miles wide flowed forty-five miles. in one case, lava traveled the first fifteen miles in two hours, but this is an unusually great rate of speed. lava streams in general seldom move faster than one or two miles per hour, and as the liquid rock gradually cools and becomes more and more viscous, the speed diminishes to zero. almost incredible volumes of steam emanate from streams of molten lava. in an outflow of lava took place from the side of kilauea mountain and ran into the sea. since that time the floor of the great crater pit (quoting professor w. h. hobbs) "has been essentially a movable platform of frozen lava of unknown and doubtless variable thickness which has risen and descended (hundreds of feet) like the floor of an elevator car between its guiding ways. the floor has, however, never been complete, for one or more open lakes are always to be seen, that of halemaumau, located near the southwestern margin, having been much the most persistent. within the open lakes the boiling lava is apparently white hot at a depth of but a few inches below the surface, and in the overturnings of the mass these hotter portions are brought to the surface and appear as white streaks marking the redder surface portions. from time to time the surface freezes over, the cracks open and erupt at favored points along the fissures, sending up jets and fountains of lava, the material of which falls in pasty fragments that build up driblet cones. small fluid clots are shot out, carrying threadlike lines of lava glass behind them, the well-known 'pelée's hair.' sometimes the open lakes build up congealed walls, rising above the general level of the pit, and from their rim the lava spills over in cascades to spread out upon the frozen floor." in some regions, like the columbian plateau of the northwestern united states and the deccan of india, each covering about , square miles, vast quantities of lava have been poured out layer upon layer to depths of even thousands of feet. distinct volcanic cones or mountains in those regions are either absent or too scarce to look to as sources of so much lava. such lava floods were probably mostly erupted from great fissures in the earth's crust, the fluidity to spread many miles. some idea of the quantitative geological importance of volcanism may be conveyed to the reader when we assert that, according to a conservative estimate, fully one-half of a million cubic miles of molten rocks have been poured out upon the surface of the earth through volcanic action in relatively recent geological time! the cascade range with its lofty peaks, including mount shasta and mount rainier, each rising more than , feet above the sea, has been built up very largely by volcanic action during the last era of geologic time. many other mountain peaks and various ranges have been similarly developed either wholly or in part. the great chain of aleutian islands extending hundreds of miles into the sea, is the scene of much volcanic activity where a great mountain range is now literally being born out of the sea by the processes of vulcanism. before this the reader has more than likely wondered about the source of the heat, vapors (mainly water), and power involved in volcanic action. answers to these questions are closely tied up with the precise cause (or causes) of volcanic action which remains one of the most uncertain of the larger problems of geologic science. before briefly discussing the causes, a few additional facts should be stated. first, in regard to the heat, a careful determination of the temperature of the molten lava of kilauea in showed it to be , degrees centigrade, or , degrees f. this is, however, a relatively low temperature, because many lavas from other regions show melting points all the way up to at least , degrees centigrade ( , degrees f.). water in the form of steam is quantitatively one of the greatest products of volcanoes. a fair idea of the tremendous volumes of water involved may be gained from the statement that a careful estimate shows that fully , , gallons of water in the form of steam erupted from a single secondary cone of mount etna during a period of days. among other gases which are given off in greater or less amounts during volcanic activity are carbonic acid gas, sulphureted hydrogen, sulphur dioxide, and hydrochloric acid. some idea of the power back of volcanoes may be gained not only from the tremendous explosions such as those above described, but also from the fact that the pressure necessary to raise the column of lava from sea level to the top of mauna loa (nearly , feet) is about , atmospheres, or about , pounds per square inch. the actual pressure must there be much greater because the lava is forced up from far below sea level. a long-held idea that a relatively thin crust covers a molten interior, and that downward pressure of this crust due to earth contraction causes molten rocks to be forced out, has been too thoroughly disproved to now be at all seriously entertained. the fact that near-by volcanoes commonly erupt entirely independently, as in the case of mauna loa and kilauea, shows that there can be no universal liquid beneath a relatively thin crust. other arguments against liquidity of the earth's interior are that the earth acts like a body nearly as rigid as steel against the powerful tide-producing forces, and that earthquake waves which pass through the earth to a depth of at least , miles are the kind which require a solid medium for transmission. let us then briefly consider more plausible views regarding the cause of volcanic action. first of all we may be sure that the earth is highly heated inside. measurements in many deep borings show that the temperature increases at the rate of about degree f. for each to feet downward, to depths greater than a mile. accordingly, on the basis of degree rise in feet, at depths of to miles, the temperature must be great enough ( , degrees to , degrees f.), to cause all ordinary rocks to melt _if they were at the surface_. at such depths, however, the downward pressure upon the rocks is so great that their melting points are notably raised, and there is every reason to believe that under ordinary conditions the rocks to miles down are not molten. if we adhere to the older (nebular) hypothesis of earth origin, the interior heat of the earth is left over from the cooling, once molten, earth. on the basis of another (planetesimal) hypothesis, the earth's heat is due to the steady, powerful action of gravity causing the earth to contract. in any case, the earth is hot inside as proved by deep well records and igneous phenomena in general, and it is a contracting or shrinking body as proved by the many large scale zones of wrinkling or folding of rocks. if, then, highly heated solid rocks at reasonable distances down in any part of the earth are subjected to relief of pressure by an earth movement such as upward crumpling of the crust, or by readjustment of large fault blocks, such heated solid rocks would become molten. the very earth movement which brings about relief of pressure and melting may very reasonably be regarded as the power which forces some of the newly formed molten material higher up into the earth's crust, and even out upon the surface. this view harmonizes with the well-known fact, already mentioned, that the main belts of active volcanoes are also the main belts of active earth movements, such as earthquakes. another source of power behind volcanic action is steam pressure. we have already mentioned the fact that vast amounts of water in the form of steam escape from volcanoes or even from streams of molten lava. the violent volcanic explosions are quite certainly all, or nearly all, direct results of sudden giving way of volcanoes to steam pressure which accumulates during greater or less periods of time, and with little or no possibility of escape, without rupturing the mountain. steam alone, or combined with some of the other gases so common as volcanic products, may also aid in forcing out molten rock. what is the source of the steam and other gases or vapors? according to one view they were originally in the earth, while according to another view the water at least has been absorbed by the molten rocks from surface waters which worked their way downward. at least two arguments oppose the second hypothesis: first, that not a few volcanoes are really many miles from the sea or other bodies of water, while downward percolation of rain water would fall far short of supplying the tremendous quantities of water ejected, and second, any water taken up by molten rock must be absorbed within a very few miles of the surface because, as we have learned, farther down there are no openings large enough to permit the downward passage of water, but, as a matter of fact, the very upper part of the earth's crust is just the place where molten rocks begin to give up their water, often with terrific violence. we may now turn to a consideration of the other very important kind of igneous activity, namely, the rise and transfer of molten materials within the earth's crust, but not to the surface. the quantity of such deep-seated (so-called "plutonic") igneous rock material which has been intruded into the earth's crust within known geologic time, is far greater than that which has been forced to surface, that is the so-called "volcanic" material. the plutonic rocks are always thoroughly crystallized, and they are generally coarser grained than the volcanic rocks. where molten materials have been forced into cracks or fissures in the crust of the earth and there congealed, we have a very common mode of occurrence called "dikes" (plate ). in many regions often one set of dikes was formed, after which one or more succeeding injections from the same or different deep-seated bodies of molten rock took place, and some of the later dikes were forced to cut across earlier ones. dikes of all lengths up to at least thirty miles, and of all widths up to many hundreds of feet, are known, but they are generally less than a mile long and not more than a few feet or rods wide. they have been intruded into all kinds of rock formations--igneous, sedimentary, and metamorphic. dikes are common in many parts of the world and they often excite the interest of lay-men. they are wonderfully displayed along the southern coast of maine. plate shows small dikes where the molten material was forced from a larger mass into a body of older dark rock. the palisades of the hudson river, just north of new york city, consists of a layer of igneous rock several hundred feet thick which, in the molten condition, was forced nearly horizontally between layers of sandstone millions of years ago, that is in the early mesozoic era. the palisade or columnar structure was caused by cracking of the rock during the cooling and contraction. this is the explanation of most columnar structures of igneous rocks, exceptionally fine exhibitions being at the giant's causeway in ireland, and devil's tower, wyoming (plate ). a type of occurrence not so common, but of special interest, is where a body of molten rock rising in nearly horizontal strata becomes cooler and therefore stiffer or more viscous and, losing its power to penetrate, forces its way between the layers causing the strata to be arched or domed over it. sufficient removal of overlying material by erosion has revealed many fine examples of this type of occurrence. another type of interest is the volcanic neck, which is the core or plug filling the feeding channel of a volcano. in certain regions, like parts of arizona and new mexico, extinct volcanic mountains may be all cut away by erosion, except the central cores or necks which, both because they are more resistant and are last to be reached by erosion, stand out conspicuously as great towers on the landscape (plate ). most important of all from the quantitative standpoint, however, are the great bodies of igneous rocks, ranging up to many miles across, which, in a molten condition, were forced irregularly into the earth's crust from unknown depths. the common rock called granite belongs in this category of rocks, which are the best and most extensively developed of all igneous types. the roots or cores of great mountain ranges often consist of such rocks which are exposed to view only after removal of great thickness of overlying material. immense areas of granite and other plutonic rocks of extra deep-seated origin are exposed, because of removal of overlying material by erosion, in southeastern canada, the adirondack mountains, new england, the piedmont plateau of the atlantic coast, and in the sierra nevada mountains. all the rock forming the lofty walls of yosemite valley is granite, which was forced into the earth's crust in relatively late mesozoic time, and which has since been laid bare by erosion. chapter ix waters within the earth it has been estimated that approximately , cubic miles of water fall upon the surface of the united states each year. about one-half of this goes back into the atmosphere by evaporation; about one-third of it flows away in surface streams; and the remaining one-sixth enters the crust of the earth. considerable water which enters the earth returns to the surface as springs, by capillarity of soils and rocks, or by being drawn up into plants and evaporated. some idea of the amount of ground water may be gleaned from the statement, based upon a careful estimate, that all the water in the rocks and soils of the first feet below the surface of the united states would make a layer seventeen feet thick. in most humid regions the soils and loose rock formations are saturated with water at greater or less depths (usually less than feet) below the surface. the surface of this saturated layer is called the ground-water level, or more familiarly the "water table." the water table shifts up and down more or less according to variation in rainfall. in addition to the water held in the loose rocks and soils near the earth's surface, large quantities occur in definite layers (usually strata) of porous rocks which very commonly extend at various angles, hundreds or even thousands of feet into the earth. a very fine illustration of this principle is the case of the dakota sandstone formation of nebraska. almost anywhere across the state a well drilled through a bed of clay and into the porous sandstone layer encounters water. (figure .) another principle is also well illustrated, namely, that water in such a porous layer may actually travel hundreds of miles, water obtained from a well sunk to the dakota sandstone having actually traveled under the surface of the state all the way from the eastern face of the rocky mountains, where rain and melting snow entered the upturned and exposed porous rock layer. another good example is iowa, where certain porous rock layers outcropping in the northwestern and northeastern corners of that and adjacent states gradually bend down under the state, reaching the greatest depths (up to , feet) far in the interior. from wells , feet deep near boone, iowa, it is, therefore, a fact that some of the water pumped out of the earth actually traveled underground all the way from beyond the corners of the state. this sort of travel of underground water is common in many parts of the world. it should be clearly understood that such water does not flow freely as in a pipe along subterranean passageways, but rather it slowly works its way between the grains of porous rock. where such water moves distinctly downward, and the porous layer has both above and below it an impervious rock layer like shale or clay, it gradually gets under greater and greater pressure. in some cases such pressure has actually been found by deep drilling to be equivalent to that of a column of water several thousand feet high. the rate of motion of water in porous underground rock layers is very slow, data from various sources indicating a rate of speed of not more than one-fifth of a mile a year in coarse porous sandstone, while in many rocks it cannot be more than ten to fifty feet per year. [illustration: fig. .--vertical (structure) section from the rocky mountains to omaha, nebraska, illustrating a widespread underground porous rock layer (the dakota sandstone) charged with water under pressure, the clay formation acting as a cap rock. (after darton, u. s. geological survey.)] we still have to consider a third mode of occurrence of waters within the earth. many formations, like granite and other types of crystalline rocks are neither in definite layers, nor are they sufficiently porous to allow water to really flow through them. where such rocks extend far down from or near the surface, how does rain water descend? it does so along cracks or fractures (both joints and faults) which we have learned are almost universally abundantly present in all hard rocks in the upper (or zone of fracture) portion of the earth's crust. joint cracks are generally very irregular in direction and spacing, while fault fractures are usually fairly regular and straight. many cracks are not wide enough to allow anything like good passageways for water, while others are sufficiently open to allow water to travel along them for hundreds, or even thousands of feet. in canyons of the west, springs not rarely emerge from the bottoms of great, nearly vertical ledges of granite and other hard crystalline rocks, the waters certainly having entered the rocks hundreds, or even some thousands of feet, higher. in rocks of the kind here considered it is evident, then, that the movements of subterranean waters must be mostly exceedingly irregular and usually not in great quantities. in many deep mines of the world, underground water causes little or no trouble except often near the surface. occasionally a shaft or tunnel strikes a prominent joint or fault fracture filled with water. what we might really call underground streams may occur only under exceptional conditions in rocks other than limestone, but in limestone they are not uncommon because the slow solubility of the rock allows underground waters to slowly enlarge the passageways to form distinct channels. echo river, which flows through mammoth cave, is a fine case in point. most water by far which emerges as springs, was at one time surface water. a simple, but common case is where rain water soaking through porous soil (e.g., sand) or rock, sinks to the top of an underlying impervious layer (e.g., clay) along whose surface it flows until it reaches the side of a valley where a spring results. in fact, wherever the water table is crossed by the surface of the ground, water must either seep or flow out. where underground streams which are common in limestone regions reach the surface on hill or valley sides, springs result. another source of springs is where under proper conditions of slope a porous rock layer, charged with water well below the surface, appears at a lower level than its source of water. still another type of spring is where a fissure or fracture crosses a water-bearing layer in which the pressure is great enough to cause the water to rise to the surface along the relatively open fissure or fracture. in various localities we hear of springs in seemingly paradoxical situations on tops of hills and even mountains. such a mystery is not difficult to clear up. in the first place, such springs are rarely at the summit of the hill or mountain. a case well known to many persons is the small, but never-failing spring a little below the summit of mount whiteface, a peak in the adirondacks, rising , feet above the general level of the immediately surrounding country. in this case, a mass of highly fractured rock, subjected to much rainfall and lying above the level of the spring, is sufficiently large easily to contain and give forth enough water to account for several such springs. in rare cases, however, springs or flowing wells are located on summits, and in such places it is only necessary to bear in mind some of the principles above set forth, but mainly the facts that water may travel under pressure long distances underground, and that the point of emergence may be on a hill which is actually lower than the source of the water far away. the economic significance of underground waters is forcibly brought to our attention when we realize that per cent of the people of the united states depend upon wells for their water supply. many city supplies, most farm supplies, and much irrigation water come from wells. the , , people of iowa, for example, are dependent upon underground waters from wells varying in depth from a few feet to several thousand feet. [illustration: fig. .--ideal section illustrating the chief requisite conditions of artesian wells. a, a porous stratum; b and c, impervious beds below and above a, acting as confining strata; f, the height of the water level in the porous bed a, or, in other words, the height of the reservoir or fountainhead; d and e, flowing wells springing from the porous water-filled bed a. (after u. s. geological survey.)] most wells are simply dug to depths a little below the water table. in humid climate regions the depths seldom exceed fifty feet. the water encountered in such wells is rarely under pressure. in some regions of deep soils or loose formations, wells are actually bored with an auger to depths of as great as feet. deep wells in relatively hard rocks are always drilled to depths of even thousands of feet. in such cases the purpose is to strike either a porous rock layer charged with water, or a crack or fissure filled with water, the water almost always being under pressure (sometimes very great), under such conditions. these are called artesian wells whether the water under pressure actually flows out at the surface or not. we may now inquire as to the necessary conditions for artesian wells. this may best be done by the aid of diagrams. figure illustrates a very common case where a porous layer, lying between impervious layers, passing under a valley, comes to the surface of the hills on each side where the water enters the porous layer. on sinking a well to the water-charged layer, the water rushes through the hole to a greater or less distance above the surface. in figure the porous and impervious layers are simply tilted, and the water under pressure rises through the free opening to the surface. wells of this kind are also common in the atlantic coastal plain of the united states. in another case, less comprehensible to the layman, the porous water-bearing stratum curves downward under a hill or mountain, water entering it where it is exposed on each side. under such conditions a flowing artesian well cannot be drilled at or near the summit, but since the water is under pressure it will rise in the hole to a level approaching that of the lowest part of the outcrop of the porous layer on either side of the hill or mountain. this is essentially the condition of things toward the interior of iowa, where water from the deeper wells rises , feet or more in the holes, but does not reach the surface. [illustration: fig. .--section illustrating the thinning out of a porous water-bearing bed. a, inclosed between impervious beds b and c, thus furnishing the necessary conditions for an artesian fountain at d. (after u. s. geological survey.)] the drilling of deep wells, where records, including samples of rock materials brought up, have been kept, has been a great aid to the geologist in determining, or rendering more precise, the knowledge of not only the kinds of rocks underground, but also the thicknesses and structural relations of the formations. in yet another way deep wells are of special significance, that is in regard to the light which they throw upon the subterranean temperature of the earth. very recently the deepest well in the world was drilled near fairmont, west virginia, to a depth of , feet, in quest of oil or gas. at a depth of , feet, the temperature was found to be degrees f. allowing for a near-surface temperature degrees, this means an average rate of increase downward of degree in feet. the second deepest well is near clarksburg, west virginia, sunk to a depth of , feet, with a temperature of degrees at the , -foot level, or at the rate of degree in feet, allowing for a near-surface temperature of degrees. it is a remarkable fact, that little or no water was encountered all the way down. a well , feet deep in southeastern germany gave a temperature of degrees at the bottom, or a rate of increase of degree in feet. these three records are about the average for the deep holes of the world. next to the deepest mining shafts in the world are in the copper mining region of northern michigan, where over , feet (counted vertically, not down the slope) down the temperature is nearly degrees the year round. the rate of increase is here less than in most wells of such depth, because of the cooling air currents. many years ago a rather remarkable experiment in well drilling was tried by the city of budapest, hungary, the attempt being to get a supply of water at the brewing temperature of degrees in order to encourage the manufacture of beer. after getting a good supply of water at a depth of , feet and a temperature of degrees, work was stopped. in building the two great tunnels (st. gotthard and simplon) through portions of the alps, such high temperatures were encountered that work was continued only under great difficulties. in the famous comstock gold and silver mine of nevada, over forty years ago, temperatures as high as degrees were encountered in the shafts at a depth of only , feet or a little over, the exceptional temperature for such depth no doubt being due to occurrence of the ores in geologically recent igneous rocks which have not yet cooled to the normal temperature for the depth of , feet. from the sanitary standpoint, wells are of very great significance, especially in view of the fact that such a large proportion of people depend upon well water. it is generally understood that typhoid fever is more common in the country than in cities, in spite of what might reasonably be expected. what are some of the causes leading up to such a situation? the idea that water purifies itself after flowing a relatively short distance is, in many cases, far from being true, especially when we are dealing with underground water. actual observations prove that germ-laden water may travel surprisingly far underground. germ-laden water from barns, cesspools, or outhouses spreads notably on sinking to the water table and it is easy to see how so many wells become contaminated. on general principles, a geologist is especially wary of water from a well in a barn yard. the well for human use at least should be located out of reasonable range of such contamination. under the condition of the diagram a well or spring some distance down the side of the hill may actually be unfit for use, though a serious situation is much less likely to develop there. nor should one assume that by locating the well on the uphill side of the house, and the outhouses or cesspool on the downhill side, safety is assured. from what we have learned in regard to earth movements, and the tilting of strata from their original positions, we know how the movement of water in the saturated zone near the surface may be downhill roughly following the hill slope, while in a tilted porous layer of rock farther below the surface the movement of water may be in just the opposite direction. a well drilled into the solid rock for safety on the uphill side of a house might derive its water from this very same porous layer, whose water has been contaminated from a cesspool or other source down the side of the hill. such a case is by no means a theory or a rarity. there is also real danger of contamination in cases where the water flows more like streams underground through cracks or fissures in hard or dense rocks, or through channels developed by solution in limestone. it may happen that water becoming contaminated from barn sites, cesspools, or outhouses finds its way along such a channel to the side or bottom of a well. the author well remembers the case of a farmer whose house, barn, and well were close together on a little limestone terrace and who continued to use the well water although he complained of its disagreeable taste, especially after a rain when he could "taste the barn in it." [illustration: fig. .--diagram illustrating a danger of contamination of wells by impure underground water. s, soil; b, bedrock; p, porous stratum. impure water from cesspool moves through porous layer to bottom of well. (by the author.)] finally, in this connection, it may be said that wells should be located in the light of the principles above explained, best of all upon the advice of some one with geological training, and that, to insure safety to health from the well water, sanitary analyses (at small cost) should be made once or twice a year. a bad well should be abandoned and a new one sunk. a large amount of money has been wasted upon, and much mystery and superstition has surrounded so-called "water witches," or those who claim some special or supernatural power of locating supplies of underground water. most common of all devices used is the so-called "divining rod," which is a forked stick of willow, witch-hazel, or other wood, according to the seemingly special requirement of the operator. certain mechanical and electrical devices are also employed. with one fork of the divining rod grasped in each hand and the main part of the stick upright, the operator walks about until, due to some "mysterious" influence, a place is found where underground water pulls the upright portion of the stick downward in spite of the grasp of the holder. some operators even claim to know just how deep a well must be sunk. without any attempt to question the honesty of all operators, geologists are in full accord with the following quotation from a paper published by m. l. fuller, for the united states geological survey: "the uselessness of the divining rod is indicated by the facts that it may be worked at will by the operator, that he fails to detect strong water currents in tunnels and other channels that afford no surface indications of water, and that his locations in limestone regions where water flows in well-defined channels are no more successful than those dependent upon mere guesses. in fact, its operators are successful only in regions in which ground water occurs in definite sheets in porous material, or in more or less clayey deposits, such as pebbly clay or till. in such regions (which are extremely common) few failures can occur, for wells can get water almost anywhere. ground water occurs under certain definite conditions, and just as surface streams may be expected wherever there is a valley, so ground water may be found where certain rocks and conditions exist. no appliance, either mechanical or electrical, has yet been devised that will detect water in places where plain common sense will not show its presence just as well. the only advantage of employing a 'water witch,' as the operator of the divining rod is sometimes called, is that crudely skilled services are thus occasionally obtained, since the men so employed, if endowed with any natural shrewdness, become, through their experience in locating wells, better observers of the occurrences and movements of ground water than the average person." it should not be assumed, however, from the above statement that the location or foretelling of underground water is mostly hopeless from a scientific point of view. in most regions the kinds of rocks which would be pierced by wells can be more or less accurately foretold by careful studies of the rocks exposed at the surface. but foretelling the underground water is often much more uncertain. where the geologic structure or arrangement of rocks in a region is fairly regular, as in the case of most sedimentary rocks, and a few scattering deep wells have been drilled, with records preserved, the geologist, by combining such data with his surface studies, can do much toward putting the facts regarding the underground waters of the region on a scientific basis. there are many such regions, an excellent case in point being iowa, regarding which state the united states geological survey has published a report containing data by the use of which it is possible to foretell almost exactly what formations would be pierced by drilling from , to , feet or more, the thickness of each, which ones are water-bearing and, in many cases, even the character of the mineralization of the water for almost any part of the state. such knowledge, through the years, is worth untold millions of dollars to the state. where the rocks are igneous and rather uniformly dense, usually little or nothing can be accurately foretold about the underground water supplies, because in such rocks the water follows exceedingly variable and irregular cracks and fissures. in metamorphic rocks the difficulties are usually about as great. in limestone regions, with humid climate, much water travels in channels underground, but these are so exceedingly irregular that there is no way of locating them by surface studies. in humid climates it seldom happens, however, that a well does not reach at least a fair supply of water within a few thousand feet even in rock formations in which the water travels along irregular cracks and channels. certain other important features of the geological work of underground water should be brought to the attention of the reader. one of these is its power to dissolve mineral substances of many kinds more or less rapidly. as already pointed out, limestone is especially susceptible to solution in water, both surface and underground. the carbonate of lime taken into solution from limestone is the principal substance which causes so-called "hard water." most of the solution takes place in the upper part of the zone of fracture of the earth's crust and the dissolved substances are carried along generally to the lower levels where they tend to deposit (and crystallize), filling fissures, cracks, and even tiny spaces between mineral grains. cracks and fissures thus filled by mineral matter from solution are called "veins." in many mining regions valuable ores and other substances have been deposited from underground water solutions and concentrated in veins. in many places underground waters with certain substances in solution travel through various rocks or encounter solutions of other substances and, as a result of chemical action, many new mineral combinations result. such actions through the millions of years of geologic time have effected great changes in many rock formations. in the case of petrification, like that of petrified wood, the buried organism slowly decomposes cell by cell, and particle by particle it is replaced by mineral matter from underground water solutions. in this manner the remarkable so-called petrified forests (not really forests) of arizona and the yellowstone park were formed, the petrifying material there having been the very common substance called silica which is the same in composition as the familiar mineral quartz. mineral matter carried in solution in surface streams is derived from ground waters which reach the surface. an idea of the tremendous quantity of mineral matter thus removed may be gained from the statement that by careful determination the mississippi river carries , , tons in solution into the gulf of mexico each year. [illustration: fig. .--structure section and part of landscape in a limestone region showing how caves and natural bridges are formed by the dissolving action of underground water. aa, limestone; bb, sink holes; dd, caves and galleries; and an arch (natural bridge) which is the remnant of a large cave. (after shaler, u. s. geological survey.)] one interesting effect of the dissolving power of underground water in limestone regions is the development of caves or caverns. most remarkable of all is mammoth cave, kentucky, with its hundreds of miles of passageways and galleries. this marvelous work of nature is all a result of the action of underground water which has dissolved and carried away vast quantities of limestone. echo river, which flows through the cavern, is still carrying on the work aided by various underground tributaries. the stalactites and stalagmites, which are so strikingly displayed in many caves, as at luray, virginia, in which water with carbonate of lime drips or oozes from the roof and, due mainly to evaporation, deposits the lime. many wonderful and fantastic effects are thus produced. where part of the roof of a cave is dissolved out, or falls in, a "sink hole" results. where all but a portion of the roof of a cave or underground channel has fallen in, a natural bridge, like the famous one in virginia, results, though natural bridges are also formed by other means. in concluding this chapter we shall briefly discuss hot underground waters, hot springs, and geysers. there are two well-known ways by which underground waters may become heated. one is by the movement of water downward into the normally heated portion of the earth, the rate of increase downward being, as above stated, degree f. for about to feet. water descending two miles would, therefore, attain a temperature of about degrees f. in some regions such a temperature may be reached at depths considerably less. such water (under pressure) taking a short course to the surface (forming springs) at a lower level would retain much of its heat taken up far below the surface. in regions where there are great down-folds of the strata (i.e., synclines), as in the central to southern appalachians, conditions appear to be favorable for such warm or hot springs, as, for example, at hot springs, virginia. a second cause of the heating of underground water is by the descent of surface waters into contact with masses of still hot igneous rock of relatively recent geologic age. in some such cases the water does not go more than some hundreds of feet down and when, under proper conditions, it returns to the surface hot and even boiling springs may result. [illustration: plate .--an upbend fold (_anticline_) in the appalachian mountain strata near hancock, maryland. the strata were deposited in horizontal layers upon the sea bottom, covering the region many millions of years ago in middle paleozoic time. at the time of the appalachian mountain revolution, near the end of paleozoic time, this and many other folds developed well below the surface. removal of overlying material by erosion has laid bare the fold as we see it to-day. (_photo by russell, u. s. geological survey._)] [illustration: plate .--(_a_) a ledge of igneous rock (granite) in northern new york. this illustrates so-called "joints" or natural cracks, commonly separating most hard rock masses into more or less prismatic blocks. (_photo by the author._)] [illustration: plate .--(_b_) a fault fracture in a ledge at east canada creek in the mohawk valley, new york. the ordovician limestone formation in thin layers on the right has sunk hundreds of feet along vertical fault to the left of middle, bringing it sharply against the older (cambrian) massive formation on the left. the hole is artificial. (_photo by darton, u. s. geological survey._)] geysers are periodically eruptive hot springs found only in a few of the volcanic regions of the world. they are most wonderfully displayed in the yellowstone national park, where they send columns of hot water to all heights up to feet at various intervals of time. almost incredible amounts of hot water are sent into the air every day in the geyser basins of yellowstone park. the single geyser "old faithful," which erupts at intervals of about seventy minutes, sends a column of water several feet in diameter to heights of from to feet. during each eruption about , , gallons of water are sent forth, or every day enough to supply the need of a fairly large city. a very brief explanation of the cause of geyser eruptions may be stated as follows: the very irregular, narrow, geyser tube extends nearly vertically downward into yet uncooled lava. the tube is more or less rapidly filled by underground water. the bottom, or near-bottom, portion of the water gradually becomes heated by the lava until finally the boiling point is reached for that depth. but, because of the pressure of the overlying water column, the boiling point at that depth is considerably greater than for the surface. a little steam develops far down and this causes the whole column of water above it to lift slightly, thus relieving the pressure on the superheated water far down. this relief of pressure allows much of the superheated water far down to flash into steam, which violently forces the column of water out of the geyser tube. chapter x how mountains come and go mountains constitute the grandest relief features of the earth, and some of the most profound lessons of earth changes may be learned by studying them. to the layman who views great mountains in all their grandeur and massiveness, the expression "everlasting hills" seems appropriate. but the geologist knows that even the loftiest mountains are only temporary features on the face of the earth. like organisms, they come and go. for example, where the great rocky mountains now stand was only a few million years ago (in late mesozoic time) the bottom of an interior sea. where the appalachians now stand there were no mountains late in the paleozoic era (not less than ten or twelve million years ago), but instead sea water covered the district. then the appalachians were formed, lifting their heads much higher than at present, after which they were cut down almost to sea level, and then once more upraised. the coast range mountains of our pacific coast have come into existence since the middle of the present (cenozoic) geologic era. every mountain, like every organism, has a life history, in some cases simple, and other cases complex. all pass through stages of birth, youth, maturity, old age, and death. some rear their heads and disappear after a short (geological) existence. others continue their growth and persist much longer, while still others undergo periods of profound rejuvenation. among the various processes by which mountain ranges have been formed, the folding and accompanying general uplift of strata are the most important. in fact, in most of the great mountain ranges of the world the folded structure is conspicuously developed, so much so that they may well be called "folded mountains." very commonly, however, mountains of this type have also been subjected to more or less fracturing of the rocks (faulting), and not uncommonly they have also been subjected to igneous activity, including both intrusion and extrusion of molten material. it is among the folded mountains of greater or less degree of complexity that the "greatest exhibitions of geologic phenomena are seen and the lessons which geology as a sciences teaches may be learned. if one desires to know the history of a region, one turns naturally to its mountain ranges, for here may be found the upturned and dissected strata, a study of whose kinds, thickness, and fossils throws light upon past events, while their foldings and dislocations show the nature and results of those great dynamic agencies which, from time to time, have operated upon the outer portion of the earth, and given to it the broad distinctive features which characterize it to-day." (l. v. pirsson.) among the great mountains we may also see wonderful exhibitions of the results of weathering and erosion, especially the work of rivers and glaciers. we can, perhaps, best convey to the reader some of the main facts and principles regarding folded mountains by considering certain observations which may be readily made in a short trip across a folded range of not too complex kind--for example, across the appalachian range along the line of the baltimore and ohio railroad, west of washington, or the pennsylvania railroad, west of philadelphia. it would be most evident that the mountains consist of strata, that is sedimentary rocks, such as sandstone, shale and limestone, which were deposited under water. a few measurements would reveal the fact that thousands of feet in thickness of strata are represented. careful measurements by geologists have, in fact, shown that the strata were originally piled up layer upon layer to a thickness of , to , feet. the fact that they are strata of such great thickness proves that sediments must there have accumulated under water for some millions of years at least. closer examination of a few good exposures (i.e., outcrops) would further reveal the presence of fossil shells and impressions of marine organisms, thus definitely leading us to conclude that the strata were accumulated under sea water, which, of course, means that the present site of the mountain range was once sea floor. examination of the rock materials also establishes the fact that the strata are such as were deposited in relatively shallow sea water--that is to say, none are at all of the sort which are now forming under really deep ocean water. most of the strata represent original sands (and even gravels) and muds which could have accumulated only relatively near shore, that is within about miles, which harmonizes with a statement made in a preceding chapter to the effect that very little land-derived sediment is at present depositing more than miles out from shore. the coarse materials (sands and gravels) could not, of course, be carried many miles out, while many of the strata are covered with ripple marks, thus positively proving their shallow-water origin. we conclude, therefore, that the appalachian strata are of marine, shallow-water origin. but we have already stated that these strata are at least , feet thick. how, then, do we reconcile these two seemingly paradoxical statements? all that is necessary is to realize that the floor of the shallow sea, in which the sediments eroded from adjacent land were being deposited, slowly, though more or less irregularly, subsided or sank during the long ages (millions of years) of their accumulation. it would carry us too far afield to really attempt an explanation of this remarkable type of geologic phenomenon, and it must suffice to suggest that, starting with the earth's crust in equilibrium, the very weight of accumulating strata would tend to destroy that equilibrium and so cause subsidence. in our trip across the mountains it would be strikingly evident that the strata are no longer in their original horizontal position, as they were piled up layer upon layer, but that they have been notably disturbed and thrown into folds (plate ), large and small, some masses of the strata having been bent upward (anticlines) and others downward (synclines). such folded structures could have been developed only by a great force of lateral compression in the earth's crust within the zone of flowage. under compression the strata were mashed together, notably bent into curves (folds), and more or less upraised. it would also be readily observed that the main axes of the folds extend essentially parallel to the main trend of the mountain range, thus proving that the force of compression was exerted at right angles to the trend of the range. [illustration: fig. .--diagrammatic sections illustrating the development of a typical folded mountain range. upper figure: a, the old land eroded to furnish sediments deposited under the adjacent sea at c. middle figure: strata (c) folded as they would appear if unaffected by erosion, and a down-warp (b) between a and c. lower figure: condition after profound erosion, and filling of b with sediment. (drawn by the author.)] using a biological analogy, a brief history of a typical folded mountain range may be stated as follows: first, there is the prenatal or embryonic stage when the materials of the range are gathering, that is when the sediments are piling up layer upon layer relatively near shore on a sinking sea bottom. next comes the birth of the range when, due to the great lateral compressive force, the strata are thrown into folds and forced to appear above sea level, the range thus literally being born out of the sea. during the next, or youthful stage, the range grows (with increasing altitudes) because of continued application of the compressive force. even during the youthful growing stage weathering and erosion attack the range and tend to reduce it. then comes the stage of maturity, when the upbuilding (compressive) force and the tearing down (erosive) force about counterbalance each other. at this time the range has reached its maximum height and ruggedness of relief, with ridges and valleys higher and deeper than at any other time. the old-age stage sets in when the upbuilding power wanes or actually ceases, and erosion dominates or reigns supreme. slowly but surely, unless there be a renewal by an upbuilding power, the range is cut down until little or nothing of it remains well above sea level, or, in other words, until a peneplain is developed. this last stage may truly be called the death of the range. usually, however, some local portions of the disappearing range, which are more resistant or more favorably situated against erosion, are left standing to at least moderate heights above the general level of the plain of erosion. the above normal order of events may be disturbed at any stage, especially after maturity, by renewed uplift when the streams are revived in activity and increased ruggedness results. even after the whole range as a relief feature has been planed away, the site of the range may be uplifted and a new cycle of erosion started. by the use of two well-known examples we shall not only illustrate the above principles of mountain history, but also show that no less than a few million years must be allowed for the growth and decay of a great folded range. during the last (permian) period of the paleozoic era the appalachian strata began to buckle and the yielding to pressure continued till well into the succeeding (triassic) period. the climax was reached about the close of the permian. then, throughout the mesozoic era, erosion reduced the central appalachians to a great plain (peneplain) near sea level, after which, about the beginning of the present (cenozoic era), the site of the former range was distinctly upraised (without folding of the rocks), causing the revived streams to begin their work of carving out the present ridges and valleys, this work still being in progress. in the case of the sierra nevadas, the strata were folded into a lofty mountain range relatively late in the mesozoic era and, by the middle of the cenozoic era, the old-age stage of erosion was well advanced when the range was not more than a few thousand feet high. then (in the middle of the cenozoic era) uplift, accompanied by faulting on a large scale, but not by folding, took place, and the range was notably rejuvenated to about its present height. all the remarkably deep canyons of the sierras have been carved out since the rejuvenation. how is the geological birthday of a mountain range determined? in the preceding paragraph we stated that the appalachians were folded and born out of the sea about the close of the paleozoic era. this is readily proved by calling attention to two facts. first, the youngest strata involved in the folding are of permian, or late paleozoic age in the geologic column, as proved by their fossil content, etc., and obviously the folding must have taken place after they had been deposited. clearly, then, the folding could not have taken place before very late paleozoic time. second, the oldest strata resting upon the folded rocks are of early (not the very earliest) mesozoic age, and these strata are somewhat tilted but not folded. obviously, then, the folding must have occurred before the nonfolded strata were deposited, which means that the folding must have been essentially completed in not later than early mesozoic time. or, in the case of the rocky mountains, we know that strata were there folded late in the mesozoic era or very early in the cenozoic era, because folded rocks as late in age as late mesozoic (cretaceous) have resting upon them, in some places, nonfolded strata of early cenozoic (tertiary) age. the figure clearly shows how the ordovician strata must have been folded before the next (silurian and devonian) strata were deposited upon them in southeastern new york. [illustration: fig. .--diagram illustrating the topography and folded structure of the appalachian mountains west of harrisburg, pennsylvania. the valleys have been etched out of belts of weak rocks, while outcropping resistant rocks stand out to form ridges. note the course of the susquehanna river across the mountain ridges, this being a "superimposed river" (see text, p. ). (drawn by a. k. lobeck.)] [illustration: fig. .--only slightly tilted strata of silurian and devonian ages resting upon folded strata of cambrian and ordovician ages in an east-west section across the catskill mountains and hudson valley of new york. the folding took place at the time of the taconic mountain revolution toward the end of the ordovician period. (drawn by the author.)] as already suggested, however, folding is not the only method by which mountains are formed. many ranges are either entirely due to the tilting of earth blocks by faulting or fracturing of the earth, or their present altitude, at least, is a direct result of faulting. such may be called block mountains. they are wonderfully represented by the various north-south ranges rising some thousands of feet above the general level of the great basin region of utah and nevada. these ranges are, in short, somewhat eroded edges of approximately parallel-tilted fault blocks lying between the sierra nevada range and the wasatch range. in southeastern oregon a series of nearly parallel block mountains, up to forty miles in length and over , feet in height, show very steep eastern fronts only slightly modified by erosion. another mode of origin of mountains is by the rise of molten material to the surface, especially where a chain of volcanoes is located. thus the cascade mountains from northern california through oregon and washington, including mounts lassen, shasta, pitt, baker, st. helens, and rainier, are very largely the result of volcanic action. the long chain of aleutian islands of alaska, referred to in our study of volcanoes, is an excellent example of a great mountain range now being built up out of the sea by volcanic action. more locally molten rocks under pressure may not reach the surface but instead simply bulge or dome the strata over them, as in the case of the group known as the henry mountains of utah, and also in other parts of the west. in still other cases mountains of considerable area and altitude have resulted from erosion of uplifted regions where the uplift has been practically unaccompanied by either folding, faulting, or igneous activity. any low-lying area, regardless of the character of its rocks, structure, or previous history, may be notably upraised and simply subjected to erosion. an excellent illustration is afforded by the catskill mountains of new york, where numerous deep valleys and narrow ridges have been carved out of upraised nearly horizontal strata. the so-called "bad lands" region of parts of south dakota and wyoming is also essentially of this type, where deep, narrow valleys and sharp ridges have been etched out of high, relatively soft, nearly horizontal strata, resulting in an almost impassable maze of mountains. in the high, recently upraised colorado plateau of parts of arizona, new mexico, colorado, and utah, nearly horizontal strata are being etched out, the result being numerous buttes, mesas (flat-topped hills and mountains) and deep canyons, including the grand canyon with its maze of peaks and pinnacles, many of them rising like mountains out of the canyon depths. mountains of the pure types just described are not the prevailing ones of the earth. most mountains and their structures, as we see them to-day, are products of two or more of the processes of folding, faulting, igneous action, and erosion. a few well-known examples will suffice to make this matter clearer. thus, the appalachian mountains originally developed by severe folding of thick strata. after considerable erosion, numerous small and large thrust faults developed, some of the dislocations amounting to miles. then the whole range was cut down nearly to sea level by erosion, after which the district was upraised (without folding) mostly from , to , feet, and the present long, narrow mountain ridges and valleys have been carved out by stream erosion. thus folding, faulting, and erosion all enter into the height and structure of the appalachians. a lofty mountain range still more complex in its history is the sierra nevada of california. first, thick strata were highly folded, upraised, and intruded by great masses of molten granite. erosion then proceeded to cut the range down to hills, after which a great fracture (fault) developed along the eastern side and the sierra nevada earth block was notably tilted with steep eastern front and long western slope. erosion has considerably modified the eastern fault face, and the deep canyons like yosemite, king's river and american river, have been carved out of the western slope of the great tilted fault block. geologically recently the central to northern portion of the range has been affected by volcanic action, streams of lava in some cases having flowed down the valleys. chapter xi a study of lakes lakes are ephemeral features on the face of the earth. compared to the tens of millions of years of known earth history, lakes, even large ones, are very short lived. they may, in truth, be regarded as merely results of the temporary obstructions to drainage. lake basins are known to originate in many ways, and there are various means by which they are destroyed. not attempting an exhaustive, scientific treatment of the subject, our present purpose may be well served by describing and explaining some of the better known and more remarkable lakes of the world. even a cursory examination of a large map of the world reveals the fact that the regions of most numerous lakes are those which were recently occupied by glaciers--either the vast ice sheets of the glacial epoch or mountain (or valley) glaciers. this is because more lakes of the present time have come into existence as direct or indirect results of glaciation than by any other cause. a considerable number of these lakes occupy rock basins which have been eroded or excavated by the direct action of flowing ice. small lakes of this sort are commonly found in the upper parts of valleys formerly occupied by mountain or so-called alpine glaciers, because there the excavating power of such glaciers was especially effective. more rarely rock basins have been scoured out by glaciers farther down their valleys. many lakes occupy rock basins excavated by ice in the high sierra nevada and cascade ranges, in the rocky mountains from colorado into canada, in the alps, and in the mountains of norway. few, if any of them are, however, large or famous. other lakes, some of very considerable size, occupy rock basins scoured out by the passage of the great ice sheets of the glacial epoch in north america and europe, though they are less common than formerly supposed. some of the many lake basins of ontario, canada, are quite certainly of this origin, as might well be expected, because the power of the great ice sheet was there in general notably greater than south of the great lakes where the tendency was to unload or deposit the eroded materials as shown by the great accumulations of glacial débris (moraines). where the ice walls of certain existing glaciers form dams across valleys, waters are ponded, a small lake of this kind occurring alongside the great aletsch glacier of the alps, where its wall is slowly moving past a tributary valley. lakes of this kind also occur in greenland and in alaska, but none are of considerable size. during the great ice age, however, literally thousands of large and small lakes were formed, both during the advance and the retreat of the ice, wherever the glacier wall blocked valleys which sloped downward toward the ice. new york state furnishes many fine examples of large and small lakes of this sort. thus, when the great glacier was melting in northern new york, waters hundreds of feet deep and many miles long were ponded between two ice lobes--one retreating eastward and the other westward from the mohawk valley. an ice dam lake was also formed a little later, when an ice wall blocked the northern part of the black river valley just west of the adirondack mountains and caused a lake covering about square miles. one of the largest of all known ice dam lakes has been called lake agassiz, which attained a maximum length of over miles and a width of miles in the red river of the north region of eastern north dakota, western and northwestern minnesota, and northward into canada, most of its area having been in canada. it began as a small lake with southward drainage into the mississippi when the great northward retreating ice sheet formed a dam across the valley of the red river of the north. the retreating ice continued to block the northward drainage until the vast lake, covering a greater territory than all of the present great lakes combined, was developed. beaches, bars, deltas and the outflow channel of this remarkable lake are wonderfully well preserved. lake winnipeg is a mere remnant of great lake agassiz. many ponds and small lakes occupy basins formed by irregular accumulations of glacial (morainic) materials. still others lie in depressions which formed by the melting of masses of ice which became wholly or partly buried by ice deposits, or by sediments washed into bodies of water which were held up by ice dams. depressions of the latter kind are commonly found as pits or so-called "kettle holes" below the general level of sand flats or sand plains of glacial lake origin. most common of all lake basins of glacial origin are those formed by accumulation of glacial débris or morainic materials acting as natural dams across valleys. this is, in fact, the most common of all ways by which existing lake basins, some of them very large, have been formed. most of the thousands of ponds and lakes of minnesota, wisconsin, and northern new york belong in this category. in the adirondack mountains, for example, most of the lakes, like the well-known lake placid, saranac lakes, long lake, and schroon lake, have their waters ponded by single dams of glacial débris across valleys. in some cases a series of such dams blockades a valley and forms a chain of lakes like the well-known fulton chain in the adirondacks. less commonly the lake may have its waters ponded by two natural dams of glacial débris, one across a valley at each end of a lake. a very fine, large scale example of the last-named type is the famous lake george in the southeastern adirondacks. it is over miles long and from to - / miles wide. it lies in the bottom of a deep, narrow mountain valley, mountain sides rising very steeply from a few hundred feet to , or more feet above its shores. there are many islands, especially in the so-called "narrows," thus greatly enhancing the scenic effect. the valley itself has been produced by a combination of faulting and erosion. there was a preglacial stream divide at the present location of the "narrows." this divide was somewhat reduced by ice erosion when the deep, narrow body of ice plowed its way through the valley during the ice age. during the retreat of the ice heavy morainic accumulations were left as dams across the valley at each end of the lake. another remarkable body of water, similar to lake george in its origin, is chautauqua lake of western new york, famous for its chautauqua assemblies. it lies , feet above sea level, with its northern end near the edge of the steep front of the plateau overlooking lake erie. chautauqua lake really consists of parts of two valleys, one sloping north and the other sloping south, each dammed by glacial deposits. the famous alpine lakes--garda, como, and maggiore--have resulted from deposition of glacial morainic materials under conditions different from those above described. in these cases great mountain or valley glaciers once flowed down the valleys and spread out part way upon the italian plain. great accumulations of glacial débris took place around the borders of the glacier lobes, and, after retreat of the ice, the glacial deposits acted as dams ponding the waters far back into the mountain valleys. the origin and history of the great lakes constitutes one of the most interesting and remarkable chapters in the recent geological history of north america. most of the salient points have been well worked out and they may be very briefly summarized, as follows: before the ice age the great lakes did not exist, because the region, prior to that time, had been land subjected to erosion for millions of years--a time altogether too long for any lake to survive. their sites were occupied by broad, low, stream-cut valleys which were quite certainly locally somewhat deepened by ice erosion during the ice age. ice erosion is, however, altogether insufficient to account for the great closed basins. the two most important factors entering into the formation of the basins of the great lakes were doubtless the great glacial (morainic) accumulations acting as dams along the south side, and the tilting of the land downward on the north side of the region. in support of this explanation it has been established that the great dumping ground of ice-transported materials from the north was in general along the southern side of the great lakes and southward. it has also been well established that, late in the ice age, the land on the southern side of the great lakes region was lower than at present, as proved by the tilted character of beaches of the well-known extinct glacial lakes which were the ancestors of the present lakes. such a down-warp of the land must have helped to form the closed basins by tending to stop the southward and southwestward drainage of the region. [illustration: fig. .--sketch map showing a very early stage in the history of the great lakes when two relatively small lakes in front of the ice wall separately drained into the mississippi river. (drawn by the author from map by taylor & leverett.)] [illustration: fig. .--lake whittlesey stage of the great lakes history when the ice had retreated far enough to allow the eastern and western ice margin waters to join with a single outlet past chicago. (drawn by the author from a map by taylor & leverett.)] [illustration: fig. .--the algonquin-iroquois stage of the great lakes when their whole area was ice-free, and all their waters drained through the mohawk-hudson valleys of new york into the atlantic ocean. (after taylor, published by new york state museum.)] we shall now very briefly trace out the principal stages in the history of the great lakes during the final retreat of the vast ice sheet. this may best be done by the aid of maps which need only brief explanation. when the ice sheet had retreated far enough northward to uncover the very southern end of the lake michigan basin and a little beyond, a small glacial lake (lake chicago) developed against the ice wall. its outlet was through the illinois river and thence into the mississippi. at the same time a larger glacial lake, held up by the ice wall, developed over the western part of the erie basin and beyond. its outlet was through the wabash river. with further retreat of the ice a large lake (whittlesey) covering considerably more than the area of lake erie developed, with outlet westward across michigan into the enlarged lake chicago which continued to drain into the illinois river. during a still later stage of ice withdrawal the remarkable set of three glacial lakes existed--lakes duluth, chicago, and lundy. each of these large lakes had its own outlet. lake duluth covered about half of the lake superior basin and drained through the st. croix river into the mississippi. lake chicago expanded to cover nearly all of the michigan basin and continued to drain through the illinois river. lake lundy covered not only more than the area of the erie basin, but also considerable territory north of detroit, and drained eastward alongside the ice lobe of the ontario basin through the mohawk and hudson valleys of new york, and into the atlantic ocean. just after the ice completely withdrew from the area now occupied by the great lakes, but still blocked the st. lawrence valley, the vast body of water called lake algonquin more than covered the sites of the present superior, michigan, and huron. at this time the land was distinctly lower toward the northeast than at present, causing the outlets to the west to be abandoned. the great lake algonquin poured its waters eastward through the trent river channel of ontario, canada, into glacial lake iroquois, which was the great ancestor of lake ontario. lake iroquois, in turn, had its outlet eastward through the mohawk and hudson valleys of new york. for part of the time at least, lake erie maintained a separate existence discharging into lake iroquois near buffalo. during the algonquin-iroquois stage the combined area of all the lakes was notably greater than the present area of the great lakes. the volume of water discharged by the lakes through the mohawk valley of new york was doubtless greater than that which now goes over niagara falls. gradually, as the st. lawrence ice lobe waned, the outlet waters of the lakes began to move alongside the ice through the st. lawrence valley. finally the ice withdrew far enough to free the st. lawrence valley and the waters of the great lakes region dropped to a still lower level, bringing about the nipissing great lakes stage not greatly different from the present. east and northeast of the lakes the land was low enough to allow tidewater (the so-called champlain sea) to extend through the hudson, champlain, and st. lawrence valleys, and possibly into the ontario basin, as proved by the occurrence of marine beaches and fossils. the waters in the erie and ontario basins covered about the present areas, while the nipissing lakes, which covered a little more than the present areas of the three upper great lakes, had their outlet through the ottawa river channel into tidewater (champlain sea). postglacial warping of the land has brought the whole region to the present condition. [illustration: fig. .--map showing next to the present stage of the great lakes history when the land was lower on the north and the upper (nipissing) lakes drained through the ottawa river valley into an arm of the sea (champlain sea) which reached through the champlain and hudson valleys. (after taylor, published by new york state museum.)] many lakes, including some remarkable ones, occupy basins which are directly due to movements of the earth's crust--either faulting or warping. an example of a lake occupying part of a fault basin is the famous dead sea of palestine. this lake lies in the lowest part of the jordan valley, which has geologically recently come into existence by the sinking of a long, narrow block of earth for several thousand feet between two great earth fractures (faults). the dead sea covers about square miles and its surface lies about , feet below sea level, which makes it the lowest lake in the world. almost equally remarkable is the fact that its depth is about , feet, so that the lowest part of the lake basin is , feet below sea level. the lake contains approximately per cent salt, mostly common table salt, causing it to be a thick brine in which there is neither plant nor animal life--hence the name "dead sea." at one time, probably just after the ice age, the lake was much larger and deeper, when it filled a considerable part of the jordan valley and had an outlet to the south. during the high-level stage the water was fresh, but gradually, as the climate became drier, evaporation was greater than intake, the outlet was abandoned, and the mineral matter (mostly chloride of magnesia and common table salt) carried by the streams in solution into the shrinking lake steadily accumulated until the high degree of salinity of the present time has been reached. great salt lake, utah, is a remarkable lake whose history has been carefully studied. it occupies the lowest position of an extensive basin which, in turn, forms but part of the whole great district of utah which has geologically recently sunk thousands of feet on the west side of the great fault already described as occurring along the western base of the wasatch mountains. at present the lake covers about , square miles, but its area fluctuates considerably. it is scarcely believable that this big lake has an average depth of only fifteen feet and a maximum depth of only fifty feet. it lies , feet above sea level, and it carries about per cent salts in solution. most abundant by far is common table salt, of which there are no less than , , , tons in solution. the waters also contain about , , tons of other salts. should the lake completely disappear by evaporation, these salts would be deposited. allowing for cars feet long and of tons capacity, a train more than , , miles long would be required to carry the salts. what has been the source of these salts? great salt lake is not, as supposed by some, a remnant of an ocean once covering the region. briefly, the explanation is as follows: at one time, when the climate was moister, the basin now only in part occupied by the lake was filled to overflowing with an outlet north into the snake and columbia rivers. that great body of water (called "lake bonneville") covered nearly , square miles and its depth was about , feet deeper than now, the present depth being very small. because it had an outlet that lake was, of course, fresh. beaches and shore lines , feet above the present lake, and at various lower levels, are still wonderfully well preserved. when, due to climatic change, evaporation exceeded intake by streams, the outlet was cut off. but slowly, as the lake shrank, streams (especially the jordan river) carried a little salt in solution, the percentage of salt increasing until the present stage has been reached. in a real sense, much of the salt was once in the sea, because it has been dissolved out of strata which accumulated under sea water long before the basin of great salt lake came into existence. another famous lake, which also occupies part of a basin due to faulting, is lake tahoe in the sierra nevada mountains, near truckee, california. this lake, whose length is miles, and width miles, lies , feet above sea level. on almost all sides steep mountains rise several thousand feet above its waters. its great depth of , feet makes it, so far as known, the second deepest lake in north america, crater lake, oregon, only outranking it. the water is exceedingly clear. an experiment some years ago showed that a white disk eight inches in diameter could actually be seen through a thickness of feet of its water. "the statement sometimes made that 'tahoe is an old volcanic crater' is not true. the region about the lake shows evidences of volcanic activity of various kinds, and the lake waters themselves have probably been dammed at times by outpourings of lava. a lava flow appears to have temporarily filled the outlet channel below tahoe city. the lake, however, lies in a structural depression--a dropped (fault) block in the earth's crust." (u. s. geological survey.) the basin of the largest lake in the world--the caspian sea--has resulted from warping of the earth's crust. it has an area of , square miles, a maximum depth of , feet, and its surface is about feet below sea level. the composition of its water and some of its animal life indicate that it was once an arm of the sea. it has been detached or cut off by an upwarp of the land between it and the black sea region. if this great lake is a cut-off arm of the sea, with no outlet, how do we explain the fact that its salinity is much less than that of the ocean? toward the north, where it is shallow and fed by so much river water, it is, in fact, almost fresh water. even the southern one-half carries not over per cent of salt. the explanation is that a steady current passes through a narrow passageway into a gulf or bay on its eastern side where evaporation is much greater than over the general surface of the caspian. the salt is, therefore, gradually accumulating at the estimated rate of , tons per day in this gulf, while the sea itself is becoming fresher. the basin of lake champlain, about miles long, was occupied by tidewater geologically very recently (that is, since the ice age), but it has been cut off by uplift of the land on the north, since which time the waters of the lake have been completely rinsed out and freshened. many lake basins directly result from volcanic action. in many parts of the world lakes, usually of small size, occupy craters of volcanoes as, for example, in the eifel region of germany, the auvergne district of france, and near rome and naples in italy. such a lake of exceptional interest fills part of the great crater, several thousand feet deep, which resulted from the explosion of mt. katmai, alaska, in . the water of this lake, more than a mile wide and of unknown depth, is hot. one of the most unique and beautiful lakes of the world is crater lake in the cascade mountains of southern oregon. it partly fills a great, nearly circular hole, six miles in diameter, with a maximum depth of about , feet, in the top of a mountain (plate ). the lake is over five miles in diameter and nearly , feet deep, making it the deepest in north america. its surface is about , feet above sea level. precipitous rock walls rising to , feet completely encircle the lake, the main body of whose water is of a marvelous deep, sapphire-blue color, while the shallow portions around some of the shore are of emerald-green. crater lake has very little intake except direct rainfall and snowfall, and its water is fresh. the great hole was not produced by an explosion like that of katmai, but rather by the sinking of the top of a once much greater mountain. that the mountain was once about the size and shape of mt. shasta is proved by the fact that deep glaciated valleys lead up the slopes and end abruptly at the very rim of the present mountain. obviously these valleys were scoured out in recent geologic time by glaciers whose sources were several thousand feet up on a former cone-shaped mountain. that the mountain top sank rather than exploded is proved by the absence of volcanic débris over the sides and base of the mountain. still another way by which lakes are formed by volcanic action is by streams of lava blocking valleys. the famous sea of galilee in palestine was thus formed by a stream of lava, which geologically recently flowed down from the east into the jordan valley and across it, where it cooled to form a dam ponding the waters of the jordan river. because the river flows through the lake, its water is fresh. one of the most remarkable facts about this lake is that its surface lies nearly feet below sea level. a number of lava-dam lakes are known in the sierra nevada and cascade mountains. a very interesting case of a lake basin, formed by cutting off an arm of the sea without any movement of the earth's crust, is the salton sink of southern california. this basin, many miles long and wide, lies below sea level, its lowest point being feet below tide. the gulf of california formerly reached much farther north and into california where it covered the site of the salton sink. gradually the colorado river, always loaded with sediment, built a broad delta deposit right across the gulf, the northern end of which thus became cut off, leaving a big salt lake. but the river flowed into the gulf, while in the dry climate the evaporation was great enough to gradually dry away the salt lake. this was the condition of things until , when much of the river at a time of flood got out of control and, following the general course of a great irrigating canal, it flowed for several years into the lowest part of the salton sink, partly filling it to form a lake miles long, miles wide, and feet deep. since the lake has been notably decreasing in size, and it may entirely disappear. other ways by which lakes, mostly relatively small ones, may develop are by landslides blocking valley drainages; by streams cutting across winding curves leaving so-called "oxbow lakes" which are common, for example, along the lower mississippi river; by wave and wind action along shores of lakes or sea; by filling so-called "sink holes" which result from dissolving or falling in of roofs of caves; and by beavers through whose industry dams are built across valleys or streams. some of the most common ways by which lakes may be destroyed are the following: by being filled with sediment carried in by streams, or by vegetation, or by both; by cutting down outlets; by evaporation due to a change in climate; by removal of the ice dam in certain types of glacial lakes; and by movements or warping of the earth's crust. chapter xii how the earth may have originated the problem of the origin of the earth is essentially astronomical rather than geological, because geological history is considered to have begun when common earth processes, such as erosion, deposition, and transportation of sediments, etc., were brought into play. it is quite certain, however, that the earth in its pregeologic state gradually merged into its geological condition. for this reason the geologist is interested in the more important doctrines or hypotheses which have been put forth to account for the origin of the earth. in fact, one of the few hypotheses which must be taken seriously is largely the work of a geologist. the most acceptable hypothesis not only best satisfies the facts regarding the earth's astronomical relationships, but also best harmonizes with our knowledge of the oldest known rocks and their history. since the problem of the origin of the earth is an essential part of the problem of the origin of the solar system, the following well-known facts should be clearly in the mind of the reader. eight planets, including the earth, revolve in nearly circular paths around the central sun, whose diameter is , miles. the radius of the solar system is at least , , , miles, this being the distance of the outermost known planet (neptune) from the sun. neptune requires years for a trip around the sun, while the earth, which averages about , , miles from the sun, makes its circuit once a year. the planets all revolve around the sun in the same direction, and in nearly the same plane. the sun and all eight planets rotate on their axes in the same direction, the earth's rotation being accomplished every twenty-four hours. most of the planets have one or more smaller bodies called satellites revolving about them, such as earth, with its one satellite (the moon), and saturn, with its eight satellites, etc. it is well known that this solar system is only a very small part of the vast universe, as shown by the facts that no star is nearer the earth than several trillion miles, and that some stars are so far away that light traveling at the rate of , miles per second requires a thousand years to reach the earth! toward the end of the eighteenth century the famous nebular or ring hypothesis was set forth by the astronomer named laplace. this assumes an original very hot incandescent mass of gas spheroidal in shape and greater in diameter than the present solar system. this mass rotated in the direction of rotation of our sun and its planets. loss of heat by radiation caused the mass to shrink, and this in turn not only made it rotate faster, but also caused the centrifugal force (i.e., the force whose direction was from the center) in its equatorial portion to gradually become stronger. finally a time came when the force of gravity (i.e., the force whose direction was toward the center) and the centrifugal force became equal and a ring was left (not thrown) off, while the rest of the mass of gas continued to shrink. after a time the material of the ring collected to form the outermost planet. the other planets were similarly formed from other rings which were left off as contraction of the great mass of gas went on. the sun represents the remainder of the great mass of rotating gas. what is the bearing of this nebular hypothesis upon the early geological history of the earth? according to the hypothesis the earth must once have been much more highly heated and larger than now. it condensed to a liquid and then it cooled enough to permit the formation of a solid crust over a liquid interior. it then had a hot dense atmosphere containing all the water of the earth in the form of vapor, and this atmosphere steadily became thinner due to absorption by the earth. when the pressure and temperature conditions became favorable, much of the water vapor condensed to form the ocean and the atmosphere gradually changed to its present condition. according to this view the oldest rocks of the earth must have been igneous because they resulted from the solidification of the outer part of the molten globe. within recent years certain serious objections to the nebular hypothesis have been raised, and chamberlin and moulton have formulated the planetesimal or spiral hypothesis as an attempt at a more rational explanation of the origin of the solar system. some of the objections to the older doctrine are that among the many thousands of known nebulæ in the universe very few only are of the laplacian or ring type, while spiral forms are abundant. spectroscopic study shows that the nebulæ are not gaseous, but made up of either liquid or solid particles, and that the leaving off of rings would necessitate the assumption of an intermittent process which could scarcely have operated under the conditions of the hypothesis. [illustration: plate .--(_a_) molten lava flowing over a cliff into water in the hawaiian islands. (_after diller, u. s. geological survey._)] [illustration: plate .--(_b_) dikes of granite (light gray) cutting an old dark rock. while the granite on the right was being forced in molten condition upward into the earth's crust, tongues of it (dikes) were sent off into the adjacent rock. (_photo by howe, u. s. geological survey._)] [illustration: plate .--(_a_) lassen peak, northern california, in eruption august , . the great cloud of steam and volcanic ash rose several miles. this is the only active volcano in the united states proper, and it is now included in lassen volcano national park. (_by permission of r. e. stinson, red bluff, cal._)] [illustration: plate .--(_b_) devil's tower, wyoming. this great mass of rock was forced in molten condition through strata which, because of their weakness, have been eroded away all around the hard igneous rock. this is probably the core or neck of a former volcano. (_photo by darton, u. s. geological survey._)] [illustration: fig. .--diagram showing the origin and character of a spiral nebula according to the planetesimal hypothesis of the origin of the solar system. (modified after moulton.)] anything like a full understanding of the planetesimal hypothesis would be difficult to obtain, and, in the brief space at our disposal, we shall attempt to make clear only a few of the salient points. according to this hypothesis the solar system was, during a previous stage of its evolution, a great, flat, spiral nebula, made up of finely divided solid or possibly liquid particles called planetesimals, among which were scattered some larger "knots" or masses. each tiny particle and larger mass or knot is considered to have traveled in its own particular orbit or path about a central very large mass--the future sun. it is even suggested that the spiral nebula originated by disruption of one star by a swift-moving passing star. each disrupted particle and large mass at first started straight for the large passing star, but because of change of position of the latter the particles and larger masses were gradually pulled around so that their paths curved into spirals. because of crossing of paths, the larger masses or knots gradually increased in size by accretion of the small particles or planetesimals. meteors (so-called "shooting stars") which now strike the earth are thought to be disrupted materials still being gathered in, though very slowly at present. after the passing star got well out of range, the spiral paths of the disrupted masses gradually changed to nearly circular, due to a wrapping-up process around the central body (sun) which then controlled the movements of the both larger masses (future planets) and small masses (planetesimals). let us now inquire briefly into the bearing of this planetesimal hypothesis upon the early geological history of the earth. according to this doctrine the earth was never in the form of a highly heated gas, nor was it ever necessarily hotter than now. instead of beginning as a much larger body which has gradually diminished in size, the earth steadily grew, up to a certain stage, by ingathering of planetesimals. increase in size caused the force of gravity to increase and this caused not only steady contraction of the earth's matter, but also a development of greater internal heat. the earth has been getting smaller ever since the force of compression has predominated over the building-up process, because of the diminishing supply of planetesimals. due to steadily increasing internal pressure and heat the various gases, including water vapor, have been driven out of the earth to form an atmosphere which has gradually become larger and denser. after sufficient accumulation of water vapor, condensation and rainfall took place; the waters of the earth began to gather to form the oceans; and the ordinary geologic processes of erosion and deposition of strata were initiated. according to this view stratified rocks could have been formed very early in the history of the earth, and in this connection it is interesting to note that the oldest known rocks are actually of sedimentary origin. chapter xiii very ancient earth history (_archeozoic and proterozoic eras_) we shall now consider the older rocks of the earth, including those of archeozoic, proterozoic, and paleozoic ages. what are the salient points in the very early history of the earth (not including the evolution of organisms) shown by these very ancient rocks? beginning with the oldest known rocks, it will be our purpose to trace out the principal recorded events of earth history in the regular order of their occurrence. as in human history, so in earth history the recorded events of very early times are fewest and most difficult of all to understand. in spite of this difficulty it is best to begin with the oldest known rocks or, as le conte has said, "to follow the natural order of events. this has the great advantage of bringing out the philosophy of the history--the law of evolution." because of limitation of space we shall give special attention to the physical history of north america, but the general principles brought out apply almost equally well to the other continents. the archeozoic rocks contain the earliest known records of geological history, or, in other words, the oldest recorded ordinary geological processes such as weathering and erosion, deposition of strata, igneous activity, etc. although we are here dealing with the most obscure records of any great rock system, partly because the rocks have been so profoundly altered (metamorphosed), and partly because of the absence of anything like definitely determinable fossils, it is, nevertheless, true that certain very important conclusions have been reached regarding this very ancient geological era. among the very oldest of all known rocks of north america are the grenville strata, so named from a town in the st. lawrence valley. in fact, no rocks elsewhere in the world have been proved to be more ancient. the grenville series consists of a great mass of sediments (strata)--original muds, sands, and limes--which were deposited layer upon layer under water (plate ). the widespread extent and character of the series in southeastern canada and the adirondacks, and more than likely far beyond these limits, make it certain that the grenville strata were accumulated on the bottom of a relatively shallow sea very much as sediments are now piling up on shallow sea bottoms. thus, the most ancient definitely known condition of the region where the grenville strata are exposed was an expanse of the sea covering the whole area. wherever, in other parts of the world, the archeozoic rocks have been studied, stratified rocks also seem to be the very oldest which are recognizable, but up to the present time no such rocks have been proved to be any older than, or even as old as, the grenville series. it may occur to the reader to ask, how long ago did the grenville ocean exist? there are grave difficulties in the way of answering this question in terms of years since we have nothing like an exact standard for such a measurement or comparison. although we must concede that not even approximate figures can be given, it can, nevertheless, be demonstrated by several independent lines of reasoning that the time must be measured by at least tens of millions of years, a very conservative estimate of the minimum time which must be allowed being about million years. in any case, the time is so utterly inconceivable to us that the important thing to bear in mind is that the great well-known events of earth history, which have transpired since the existence of the grenville ocean, require a lapse of many millions of years, as shown by revolutionary changes in geographic and geologic conditions such as the long periods of erosion, the enormous accumulations of sediment, the repeated spreading out and disappearance of sea water over many portions of the earth, and the building up and tearing down of great mountain ranges at various times. the ideas here expressed will be much better appreciated by the reader after following through the salient points in the history of north america as set forth in the succeeding pages. again, the reader may ask, by what line of reasoning do we conclude that these stratified rocks are so exceedingly ancient? all rocks of archeozoic age, including strata as well as certain younger igneous rocks (see below), invariably occupy a basal position in relation to all other rock systems. they constitute a complex lot of crystalline metamorphic rocks, combining certain characteristics which lie below the base of the determined sedimentary succession. where rocks with the characteristics of the archeozoic are separated from the oldest paleozoic (cambrian) strata by the great sedimentary or metamorphic system known as the proterozoic (see below), we may be sure that we are dealing with archeozoic rocks. if the series of rocks in question belongs in the archeozoic system, all that remains is to determine its age position in that system. this can usually readily be done because wherever they have been studied the archeozoic rocks may be subdivided into two groups of rocks, a sedimentary and an igneous. where the igneous rocks, mainly granites and related types, occur associated with the sedimentary rocks (e.g., grenville), they very clearly were forced or intruded, while molten, into the sedimentary rocks, thus proving these latter to be the older. since the archeozoic strata of the adirondack mountains, southeastern canada, and also all, or nearly all, other known districts are mostly badly disturbed, tilted, and more or less bent or folded, and since neither top nor bottom of the piles of strata has ever been recognized as such, it is impossible to give anything like an exact figure for the thickness of the series. continuous successions of strata have, however, been observed in enough places to show that they were commonly deposited layer upon layer to a thickness of at least some tens of thousands of feet. a thickness of over , feet has been reported from southeastern canada. the clear implication is that the archeozoic sea which received sediments must have existed for a vast length of time which must be measured by at least some millions of years, because in the light of all our knowledge regarding the rate of accumulation of sediments a very long time was necessary for the piling up of such thick masses of strata. it does not, however, necessarily follow that the grenville ocean was many thousands of feet deep where deposition took place. in fact, the very character of the original sediments (muds, sands, and limes) clearly indicates that the archeozoic sea in which they accumulated was, for most part at least, of shallow water because such sediments have rarely, if ever, been carried out into an ocean of deep water. the great ocean abysses of to-day are not receiving any appreciable amount of land-derived sediment. thus we are forced to conclude that in archeozoic time, as well as many times in later ages, the shallow sea bottom gradually sank while the sediments accumulated. even more conclusive proof of such subsidence has been obtained from the study of so-called "folded" mountain ranges of paleozoic and later time, an excellent example being the appalachian range. having established the sedimentary origin and great antiquity of the grenville series, we are led to the interesting and important conclusion that these oldest known rocks are not the most ancient which ever existed, because the grenville strata must have been deposited layer upon layer, upon a floor of still older rocks. if such still older rocks are anywhere exposed to view, they have never been recognized as such. again, the fact that the most ancient known rocks were deposited under water carries with it the corollary that there must have been lands at no great distances from the areas of deposition because, then as now, such sediments as muds and sands could have been derived only from the wear or erosion of lands, and have been deposited in layers under water adjacent to those lands. but we are utterly in the dark regarding any knowledge of the location or character of such very ancient lands. the most ancient known strata, as we see them to-day, do not look like ordinary sediments such as shales, sandstones, and limestones. they have been profoundly changed from their original condition, that is to say, they have undergone metamorphism. the archeozoic strata now exposed to view were formerly buried at least some miles below the earth's surface, the overlying younger rocks having since been removed by erosion through the millions of years of time. far below the earth's surface, under conditions of relatively high temperature, pressure, and moisture, the materials of the strata were completely crystallized into various minerals. the surfaces of separation of the very ancient layers of sediment are still usually more or less clearly present (plate ). original limestone has been changed into crystalline limestone or marble; sandstone has been changed into quartzite, and shale, sandy shale, and shaly sandstone have been changed into various schists and gneisses. in western ontario there are also stratified rocks (called the keewatin series) which seem to be of about the same age as the grenville strata farther east. a point of special interest in connection with the keewatin strata is the presence of layers of lava in portions of the series, thus proving that molten rock materials were poured out on the earth's surface during the most ancient known era of the earth's history. after the accumulation of the very ancient archeozoic sediments igneous activity took place on grand scales when great masses of molten rock were forced (intruded) into the sediments from below. masses of molten materials are known to have been thus intruded at several different times, but of these the most common by far cooled to form a great series of granite and closely related rocks. the general effect was to break the old strata up into patches or masses of varying sizes as clearly shown by the present distribution and modes of occurrence of these igneous rocks. in most cases the strata were pushed aside by, or tilted or domed over, the upwelling molten floods--in many cases the molten materials were, under great pressure, intimately forced or injected into the strata; numerous large and small masses of strata were caught up or enveloped (as inclusions) in the molten floods; in some cases there was local digestion or assimilation of the strata by the molten materials, while in still other places large bodies of strata seem to have been left practically intact and undisturbed. such igneous rocks, which are very widespread, are all of the plutonic or deep-seated types; that is, they were never forced up to the earth's surface like lavas, but they solidified at considerable depths (at least some thousands of feet) below the surface. we see them exposed to-day only because a tremendous amount of overlying rock materials has been removed by erosion. these igneous rocks are generally easily distinguished from the old sediments of grenville age because of their more general homogeneity in large masses, and their lack of sharply defined bands or layers of varying composition. the fact that the minerals have always crystallized to form medium to coarse-grained rocks shows that these rocks solidified under deep-seated conditions, since it is well known that surface flows (lavas) are much finer grained commonly with more or less of the rock not crystallized at all. slow cooling under great pressure favors more complete crystallization with growth of larger crystals. as we have just learned, the very character and structure of the archeozoic rocks now exposed to view show conclusively that they were formerly deeply buried, and the inference is perfectly plain that the overlying rock materials were removed by erosion. profound erosion of any land mass means that the land must have stood well above sea level, and thus we come to the important conclusion that the great mass of archeozoic rocks (both strata and igneous rocks) were upraised well above sea level. just when the uplift occurred cannot be positively stated, but in every region where the matter has been studied it took place before the strata of the next geological era began to deposit as shown by the fact that such later strata rest upon the profoundly eroded surface of the archeozoic rocks. such an erosion surface, called an "unconformity," marks a gap in the geological record of the district where it occurs. there is much to support the view that the uplift was concomitant with the great igneous intrusions, especially the granite. it is reasonable to believe that the same great force which caused the welling up of such tremendous bodies of liquid rock into the earth's crust might easily have caused a decided uplift of a whole large region, but even so the process must have been geologically slow. in regard to the height of those ancient lands, the character of the topography, and the drainage lines we are as yet utterly in the dark. the fact that many thousands of feet in thickness of materials were removed by erosion to expose the once deeply buried rocks, does not necessarily imply that the lands at any time had great height, because it is possible that while elevation slowly progressed, much material was steadily removed by erosion. in the light of our knowledge of the origin and growth of mountain ranges of later time there is little doubt that at least some of the archeozoic lands were raised to such mountain heights. thus far in our study of the archeozoic rocks attention has been mainly directed to southeastern canada and the adirondack mountains, where careful studies have been made. in all parts of the world where the most ancient known (archeozoic) rocks have been studied in detail the same general principles apply. particular attention has been given to the archeozoic rocks south of lake superior, and in the piedmont plateau of the eastern united states. in the accompanying map archeozoic rocks are widely exposed to view within the areas shown in black. it has been estimated that archeozoic rocks appear at the surface over about one-fifth of the land area of the earth. where they are not at the surface it is believed that they everywhere exist under cover of later rocks. in other words, archeozoic rocks are considered to be almost universally present either at or under the earth's surface. this is true of the rocks of no other age. special mention should be made of the fine exhibitions of archeozoic rocks in scandinavia and the highlands of scotland. [illustration: fig. .--map showing the surface distribution of archeozoic and proterozoic rocks in north america. (redrawn by the author after u. s. geological survey.)] all known evidence leads us to the remarkable conclusion that the climate of much, or possibly all, of archeozoic time was not fundamentally different from that of to-day. there must have been weathering of rocks, rainfall, and streams much as at present as proved by the character and composition of the stratified rocks which formed in that remote era. the presence of graphite ("black lead") in crystalline flakes scattered through many of the strata shows that the climate must have been favorable to some form of life, because graphite thus occurring quite certainly represents the remains of organisms, this matter being more fully discussed in a succeeding chapter. in passing it may be stated that climatic zones were then probably scarcely if at all marked off, as they quite certainly were not even during paleozoic time. one of the great contributions of geology to human knowledge is that during the tens of millions of years from archeozoic times to the present the earth's climate has undergone no fundamental change or evolution. in the earlier ages there was greater uniformity of climate over the earth, and, during known geologic time there have been rather localized relatively minor fluctuations giving rise to glaciers, deserts, etc., but there has been no real evolution of climate at all comparable to the marvelous evolution of organisms--both animals and plants. we shall now turn our attention briefly to a consideration of the second great subdivision of geologic time--the proterozoic era. rocks of proterozoic age comprise all of those which were formed after the archeozoic rocks and before the deposition of the earliest paleozoic (cambrian) strata, these latter being rather definitely recognizable because they contain fossils characteristic of the time. cambrian strata are, in fact, the oldest rocks which contain anything like an abundance of fossils, so that the separation of rocks of either archeozoic or proterozoic age from the earliest paleozoic is seldom difficult. but how may we separate the proterozoic rocks from the archeozoic? fossils afford us no aid whatever, because no determinable fossils have been found in rocks as old even as the earlier proterozoic. the two great groups of very ancient rocks do, however, show a number of differences which must be considered together. thus, igneous rocks distinctly predominate in the archeozoic, while stratified rocks predominate in the proterozoic. all archeozoic strata are thoroughly metamorphosed (changed from their original condition), while large masses of the proterozoic strata are only moderately metamorphosed, or even unaltered, and therefore look much like ordinary strata of later ages. archeozoic rocks have almost invariably been notably deformed by more or less folding, tilting, etc., while the proterozoic rocks show relatively much less deformation. another important criterion is the fact that the proterozoic rocks, wherever they have been studied in relation to the archeozoic rocks, always rest upon a profoundly eroded surface of the latter, that is, an unconformity separates the two great sets of rocks. this erosion surface is of still further interest because it is the very oldest one known, none having been recognized within the archeozoic group itself. even where the proterozoic strata have been considerably metamorphosed and deformed, this old erosion surface may be recognized, and if the rocks below that surface possess the characteristics of the archeozoic rocks as described above, the two great very ancient rock groups may be distinguished. one of the triumphs of geology during the last to years has been the recognition of the great rock group (proterozoic) between the archeozoic and paleozoic, thus bringing to light the records of an era which lasted many millions of years. the length of time represented by the proterozoic era is by many believed to have been fully as long as all succeeding eras--paleozoic, mesozoic, and cenozoic--combined. twenty million years would be a very conservative estimate for the duration of the era. what is the nature of the evidence as recorded in the rocks which lead us to conclude that the proterozoic era lasted such a vast length of time? the great thickness of proterozoic strata (over , feet in the lake superior region), in the light of what we have already learned regarding the present rate of wear (erosion) of lands and deposition of the eroded materials under ordinary conditions, clearly implies millions of years of time for their accumulation. but the proterozoic strata as we now see them are in most places not a continuous pile, that is they were not accumulated layer upon layer without notable interruption. thus, the thick proterozoic group of the lake superior region has been divided into four distinct, mainly sedimentary series separated from each other by erosion surfaces (unconformities). each erosion surface represents a long time when the area was elevated and underwent profound wear before the next series of strata accumulated on the worn surface. that such times of erosion were geologically long is proved not only by the profound alteration (metamorphism) of one set of strata before another accumulated, but also by the fact that granite, which, as we have learned, is never exposed except where much overlying material has been eroded, actually formed parts of surfaces of earlier proterozoic rocks upon which later ones were deposited. in the lake superior region there are not only three great erosion surfaces (unconformities) within the proterozoic group, but also one at the base separating it as a whole from the archeozoic group, and another at the top separating it from the paleozoic group. it is, therefore, fair to conclude that the amount of time (millions of years) represented by these great erosion intervals was fully as great as the time needed for deposition of the existing proterozoic strata. in the lake superior region the older proterozoic strata are nearly all more or less folded and altered (metamorphosed), and they have been intruded by considerable bodies of molten rock, mostly granite. the later proterozoic strata have been much less deformed and in many cases they are practically unaltered. in this region a very remarkable event took place in late proterozoic time. this was volcanic activity on a grand scale. we may gain some idea of the stupendous and long-continued volcanic outpourings from the fact that, based upon actual measurements of thickness, lava sheets, averaging about feet thick, poured out one upon another until a pile about six miles high had accumulated. in parts of the grand canyon of the colorado tilted proterozoic strata may be seen resting upon the profoundly eroded surface of the archeozoic rocks of the inner gorge. the proterozoic strata, , feet thick, consist of practically unaltered sandstones, shales, and limestones, associated with some layers of basaltic lava. an erosion surface (unconformity) separates the whole group into two distinct series, and the group is separated from the overlying nearly horizontal paleozoic (cambrian) strata in the walls of the canyon by another erosion surface. more recently the proterozoic strata so finely displayed in the rocky mountains of montana and southern canada have been studied. these strata, at least two or three miles thick, are mostly unaltered sandstones, shales, and limestones, associated with some metamorphic and igneous rocks. as usual, these strata rest upon the eroded archeozoic. they were more or less upturned and folded before deposition of the succeeding paleozoic strata. satisfactory subdivisions have not yet been worked out. in north america most of the areas shown on the accompanying map contain more or less proterozoic rocks. rocks of this age are known to some extent in all continents where their general relationships seem to be much like those of north america. they have perhaps been most carefully studied in scandinavia and the highlands of scotland, where the strata portions are about two miles thick. the climate of proterozoic time must, for most part, have been about like that of to-day except, of course, for its much greater uniformity over the earth. about a dozen years ago very typical glacial deposits were discovered within the early proterozoic rocks of western ontario, canada. a climatic condition favorable for the development of glaciers so early in the history of the earth is, to say the least, directly opposed to an idea (based upon the nebular hypothesis) long held that the climate of early geologic time must have been much warmer than that of the present. chapter xiv ancient earth history (_paleozoic era_) beginning with the earliest paleozoic, the legible records of events of earth history are far more abundant and less defaced than those of earlier times. stratified rocks of the ordinary kinds greatly predominate over the igneous and metamorphic rocks, and the strata are in general far less disturbed than those of the archeozoic and proterozoic groups. from the earliest paleozoic we have also the first abundant records (fossils) of the life of the earth, so that the ordinary methods of subdividing and determining the relative ages of the paleozoic and later strata, as well as correlating the subdivisions (formations) in widely separated regions, can be used. from here on in our discussion of earth history we shall be able to trace the salient features of the changing outlines of the face of the earth, the coming and going of the seas over the lands, and the evolution of animals and plants with a considerable degree of definiteness and satisfaction. first, we shall trace out, in the regular order of their occurrence, the main physical history events of paleozoic time, leaving a consideration of the evolution of life for other chapters. because of limitation of space, our attention will be almost wholly centered upon the continent of north america, but the reader should bear in mind that the general principles and facts set forth apply with about equal force to most other continents. in europe the wonderful records of paleozoic history are found in strata, whose estimated maximum thickness is about , feet! it must not be thought, however, that all these strata are piled up in a single locality, but the figure does actually represent the sum total of the greatest thickness of the many subdivisions (formations) of the paleozoic rocks in different portions of the continent. in north america the maximum thickness of all paleozoic rocks seems to be no less than , feet. more than , feet of strata may actually be observed piled layer upon layer in the highly folded and deeply eroded central appalachian mountains. the great thickness of the strata, combined with the facts that the fossils show that many marvelous, mostly progressive, changes took place among living things, that seas came and went repeatedly over many parts of the continent, and that great changes took place in the configuration of the land, force us to conclude that paleozoic time must have lasted for many millions of years. just before the opening of the paleozoic era practically all of north america appears to have been dry land, which had undergone so much erosion that it was low and far less rugged in relief than at present. this we know, because the rather widespread early paleozoic (cambrian) strata almost everywhere rest upon deeply eroded rocks of either archeozoic or proterozoic age. considering both the time involved and the wide area affected, we have no record of anything like such a profound erosion interval since the beginning of the paleozoic era. it seems that the constructive or upbuilding forces within the earth were then remarkably quiescent, while the destructive forces (erosion) were almost unhampered in their work of cutting down the land. have we any definite idea of the relations of land and water in north america during the first or cambrian period of the paleozoic era? in the affirmative answer to this question, certain principles will be brought out which the reader should keep in mind as we trace out the succeeding great physical changes in the history of north america. it should, however, be remembered that, in the brief space at our disposal, only the most general, or the most significant localized, physical changes in the long and intricate known history of the continent since the opening of the paleozoic era can be brought out. in early cambrian time a narrow arm of the sea (like a strait) extended from the gulf of st. lawrence southward across eastern new york and over the site of the present appalachian mountains connecting with the gulf of mexico on the south. on the west, a much larger and broader arm of the sea (like a mediterranean) extended from alaska southward over the site of the rocky mountains of canada and across the sites of the columbia plateau to great basin of the western united states. all the rest of the continent was land, apparently almost or wholly devoid of high mountains. by what process of reasoning do we conclude that arms of the early cambrian sea reached across eastern and western north america? first, wherever marine strata of definitely determined early cambrian age now occur, the early cambrian sea must have existed because those strata were obviously deposited in that sea. second, to those areas we must add others from which it can be demonstrated that early cambrian marine strata have been removed by erosion. enough field work along these lines has been done in north america to render it practically certain that the relations of land and water during early cambrian time were essentially as above outlined. [illustration: fig. .--map showing the relations of land and water in north america during early cambrian time, at least , , years ago. lined areas represent land. (principal data from a map by willis published in the journal of geology.)] [illustration: fig. .--map showing the relations of land and water in north america during middle ordovician time. lined areas represent land. (principal data from a map published by willis in the journal of geology.)] as cambrian time went on, the marine waters gradually spread from south to north across most of the mississippi valley area, causing the eastern and western arms of the sea to be connected, thus forming an interior continental sea. otherwise the relations of land and water were much as in early cambrian time. we know that the sea transgressed northward across the mississippi valley district because, on the south, the whole cambrian system of strata (lower, middle, and upper) is present, while, farther north, only middle and upper cambrian are present, and, farthest north, only upper cambrian strata occur. this progressive northward overlap of younger and younger (later) cambrian strata upon the old rock floor proves, that the cambrian sea steadily spread farther and farther northward over the mississippi valley area. that this spreading sea was shallow is amply demonstrated by the deposits it left, such as shales, conglomerates (i.e., consolidated gravels) and sandstones, often ripple-marked. the cambrian strata of north america vary in thickness from less than , feet to about , feet. in the mississippi valley the cambrian strata are unaltered and almost undisturbed from their original horizontal position. in the appalachian mountains of the east, and the rocky mountains of the west, the strata are commonly notably folded and faulted. in some places, as in western new england, the strata have been notably altered (metamorphosed). the best estimates for the duration of the cambrian period range from , , to , , years. it is a remarkable fact that, during this great lapse of time, north america was unaffected by any great physical disturbances such as mountain making, emergence of large tracts of land, or igneous activity. the one great physical event of the cambrian was the gradual submergence of a considerable portion of the continent. that the climate of the earliest cambrian was at least locally favorable for the existence of glaciers, is proved by the occurrences of true glacial deposits in rocks of that age in china, norway, and australia. it is a remarkable fact that the glacial materials of china occur along the yangtse river, thus demonstrating that conditions for glaciers then existed at a latitude as far south as new orleans. these evidences of glaciation directly refute the old idea, based upon the nebular hypothesis, that the climate of the paleozoic was distinctly warmer than now. the glacial evidence, added to our knowledge of the character and world-wide distribution of many identical species of animals, leads us to conclude that early paleozoic climate was not essentially different from that of very recent geologic time, but that the climate was then much more uniform than at present. during the second or ordovician period of the paleozoic era, the progressive submergence of cambrian time continued until a climax was reached toward the middle of the period when fully four-fifths of the continent was submerged under shallow sea water. since middle ordovician marine strata are more widespread than the rocks of any succeeding age, we can be reasonably sure that so much of the continent was never again covered by the sea. in fact, so far as the records have been interpreted, this came nearest to being a universal flood in the whole known history of the continent. by the very character of the rocks deposited (seldom over a few thousand feet thick), we can be sure that the middle ordovician continental sea was everywhere far shallower than the great ocean abysses of to-day. because the lands were so low and restricted, relatively little land-derived sediment washed into the sea. but the shallow sea water was inhabited by millions of animals, the shells of many of which slowly accumulated to build up the thick bodies of limestone strata (plate ) which constitute the main bulk of rock of early and middle ordovician age. the famous trenton limestone, named from a locality in central new york, with its great abundance of fossils, was formed mostly by the accumulation of shells of animals during middle ordovician time. later in the ordovician there was a considerable shift in level between land and water causing a withdrawal of much of the widespread sea. as a result of the generally more elevated lands, erosion proceeded more vigorously, and sands and muds were more abundantly deposited in the restricted sea, these sediments having consolidated to form the shales and sandstones which predominate among the upper ordovician rocks. a principle above briefly explained in the discussion of the cambrian may be reemphasized here. it is as follows: in making a map to show the relations of land and water, say during middle ordovician time, the geologist is by no means dependent only upon actual surface exposures of middle ordovician strata. such exposures fall far short of giving an adequate conception of the former or even present real extent of such strata. in many places originally present ordovician strata have been removed by erosion. an excellent case in point is the adirondack region of northern new york. on the west side of the adirondacks a great pile of marine ordovician strata , feet thick end abruptly on the gently sloping flank of the mountains, thus clearly proving that the strata formerly extended at least twenty to thirty miles eastward. again, in the southern adirondacks a small area of very typical marine middle ordovician strata lies fully fifteen miles from the general area of such rocks to the south. this small body of rock is very clearly only an erosion remnant of a general sheet of middle ordovician rock which once covered the whole intervening district. in many other regions the middle ordovician strata are definitely known to be concealed under cover of later rocks, as in the mississippi valley, where the actual surface exposures constitute only a fraction of the middle ordovician strata which underlie nearly all the valley, as proved by deep well drillings, study of the scattering outcrops, etc. in still other places, middle ordovician strata, associated with other rocks, are highly folded, as in the appalachians, where such strata outcrop in only narrow belts following the trend of the folds. in short, then, wherever it can be proved that middle ordovician marine strata are visible at the surface, or are concealed under other rocks, or were once present, we can be sure that the middle ordovician sea existed. exactly this principle applies to any subdivision of geologic time. [illustration: fig. .--structure section showing rocks representing three geologic eras separated by millions of years of time. length of section miles, vertical scale much exaggerated. at the bottom are archeozoic (precambric) rocks and resting upon them on the left are early paleozoic strata , feet thick. a glacial lake deposit of late cenozoic age lies on the archeozoic rock toward the right. it is evident that the paleozoic strata formerly extended much farther eastward. (by the author as published in a new york state museum bulletin.)] the ordovician period closed with a great mountain-making disturbance in eastern north america, and at the same time all, or nearly all, of the continent was land. throughout most of the cambrian and ordovician periods, the strata accumulated to a thickness of thousands of feet in the marine waters which spread over the eastern border of new york, the sites of the green mountains of vermont, the berkshire hills of massachusetts, and southward at least as far as virginia, over the area of the piedmont plateau. at, or toward the close of the ordovician period, a great compressive force in the earth's crust was brought to bear upon the mass of strata and they were tilted, highly folded, and raised above sea level into a great mountain range known to geologists as the taconic range. it is quite the rule throughout this region of taconic disturbance to find the strata either on edge or making high angles with the plane of the horizon. many of the folds were actually overturned, and in some cases notable thrust faults developed, that is, the upper strata broke across and great masses were shoved over each other. these facts all go to show that the mountain-making compressive force applied to the region was of rather an extreme type. since the origin of the taconic range a tremendous amount of erosion has taken place, so that literally only the roots of the range are now exposed in the green mountains, berkshire hills, highlands-of-the-hudson, and the northern piedmont plateau. how do we know that the taconic disturbance took place toward the close of the ordovician period? by way of answer to this question two facts need to be considered. first, relatively late (or young) ordovician strata are involved with the folds, thus proving that the folds formed after those late ordovician sediments were deposited. second, undisturbed strata formed during the middle of the next (silurian) period, rest upon the eroded edges of the folds, which proves that the folds must have developed well before middle silurian time because the only time they were subjected to erosion must have been during early silurian time. [illustration: fig. .--structure section showing profile and underground relations of the rocks across part of the highlands-of-the-hudson region in southeastern new york. length of section, sixteen miles. the rocks are mostly of prepaleozoic age, but with belts of highly infolded early paleozoic strata toward the middle right. (after berkey, new york museum report.)] mention should also be made of the profound metamorphism (alteration) of the cambrian and ordovician strata along the main axis of the range, where the intense compression, aided by heat and moisture, caused the deeply buried portions of the strata to become plastic, and hence they became more or less foliated (cleavable) and crystallized into various metamorphic rock types, the limestone having changed to marble, the shale to slate or schist, and the sandstone to quartzite. thus we explain the rocks of the extensive marble quarries of vermont and western massachusetts, the slate quarries of central eastern new york, and the berkshire schist of the berkshire hills of massachusetts. one of the grandest and most significant of all the profound geological processes is the birth and history of a great folded mountain range. since the taconic range affords us such an excellent example of a large-scale, well-understood folded range of great antiquity we may do well to consider it in the light of certain other broad relationships. the great compressive force which folded and upraised the taconic mountains did not accomplish its work rapidly in the ordinary human history sense of the word. the force was slowly and irresistibly applied, and the strata well below the surface were gradually bulged or folded, or fractured where near the surface, the length of time required for the operation having been, at the very least calculation, some hundreds of thousands of years, and more than likely a million years or more. such a length of time is, however, so short compared with all known earth history, that we are accustomed to refer to the formation of such a mountain range as simply an event of geological history. even before such a range attains its maximum height a very considerable amount of erosion has already taken place. when the first fold appears above sea level, erosion begins its work and continues with increasing vigor as the mountain masses get higher and higher. thus we have warfare between two great natural processes--the building up and the tearing down. after a time the building-up process wanes and then ceases, while the tearing-down process (erosion) continues either until the whole range has been completely worn down or until some rejuvenating force causes a renewed uplift. here is an example of one of the remarkable procedures of nature. after millions of years of work causing the deposition of thousands of feet of strata, piled layer upon layer on the sea floor, a force of lateral pressure is brought to bear and a mountain range is literally born out of the sea. no sooner is the range well formed than the destructive processes (erosion) unceasingly set to work to destroy this marvelous work. but the sediments derived from the wear of the range are carried into the nearest ocean again to accumulate and, perchance, after long ages, to be raised into another range; and so the process may be often repeated. from this we learn that the mountain ranges of the earth are by no means all of the same age. the original adirondacks were formed long before the taconics, which originated millions of years before the appalachians, these latter having been folded up long before the sierras. the rockies, followed by the coast ranges, are each younger than the sierras as regards their original folding and uplift. among foreign countries special mention should be made of the british isles, where ordovician strata thousands of feet thick were, late in the period, notably folded and upraised, the crustal disturbance having been accompanied by great intrusions of molten rocks and vast outpourings of lavas, so that this region ranks among the greatest of the ancient volcanic areas of europe. [illustration: fig. .--map showing the general relations of land and water in north america during middle and late middle devonian time fully , , years ago. (after willis, courtesy of the journal of geology.)] we shall now turn our attention to a very brief consideration of the salient points in the physical history of north america during the next great period (silurian) of the paleozoic era. as a result of the physical disturbance late in the ordovician the great interior sea was largely or wholly expelled from the continent, and this was essentially the condition of the continent at the beginning of the silurian. but this condition was of short duration, for early in the silurian the sea again began to spread, gradually increasing in extent to a climax in about the middle of the period. at this time the famous and extensive niagara limestone, so named from the rock at the crest of niagara falls, was deposited. except for the newly formed taconic range, standing out as a bold topographic feature along the middle atlantic coast, and a somewhat wider extent of land, the condition of the continent during middle silurian time was very similar to that of middle ordovician time. [illustration: fig. .--map showing the general relations of land and water in north america during middle mississippian time. (after willis, courtesy of the journal of geology.)] soon after mid-silurian time the seas became greatly restricted almost to disappearance as such. in the eastern united states and southeastern canada strata of that particular age are found only in parts of ontario, new york, ohio, michigan, and from pennsylvania southward to west virginia, where they are characterized by red shales and sandstones, and salt and gypsum deposits. such materials containing few fossils very clearly indicate deposition in either extensive lagoons or more or less cut-off arms of the sea under arid climate conditions rather than in ordinary marine water. still later in the silurian the interior seas were partially restored, as shown by the fact that true marine strata corresponding to that age not only cover the salt and gypsum deposits, but are notably more extensive than they. about the close of the silurian period almost all of the continent was dry land. unlike the ordovician period, the silurian closed without any mountain-making disturbance or great uplift of land. the silurian period, like the preceding ordovician and cambrian, seems to have been free from any more than slight igneous activity as, for example, in maine and new brunswick. the total thickness of silurian strata in north america is seldom more than a few thousand feet. the salient features of the physical history of the next, or devonian period, are much like those of the preceding silurian. at the beginning of the devonian almost all of the continent was dry land, but soon a long, narrow arm of the sea extended across the eastern side of the continent from the gulf of st. lawrence southward through western new england, southeastern new york and throughout the appalachian district, thus reminding us of the long, narrow sound which occupied almost exactly the same territory during the early part of the cambrian period. in the west the only water was a small embayment reaching across southern california into nevada. by middle devonian time these water areas had considerably expanded. during relatively late devonian time the sea was so expanded as to cover much of the mississippi valley area, the appalachian mountains and st. lawrence valley areas, and most of the site of the rocky mountains, except for an island of considerable size reaching from new mexico through wyoming. the main lands were most of northeastern north america, a large land area extending from florida to nova scotia, and a large area on the western side of the continent from california to alaska. a remarkable formation of late devonian age should be briefly described. in southeastern new york and the northern appalachian region there was a tremendous accumulation of sediments which have consolidated into sandstone, together with some shale and conglomerate. this so-called "catskill" formation is from , to , feet thick and is well shown as the main body of rock in the catskill mountains. it is largely a shallow-water deposit of essentially nonmarine origin, as proved by coarseness of material, ripple marks, and nonmarine fossils. all evidence points to the origin of this remarkable formation as a great delta deposit built out into the shallow interior sea. notable thinning toward the west, with increasing fineness of grain of material, shows that the sediment came from the east, no doubt carried by a large river from the small continental land mass (called "appalachia") on the eastern side of north america. the maximum thickness of the north american devonian seems to be about , feet in the northern appalachian region, but elsewhere it generally ranges from , to , feet thick. in north america the subdivisions of the devonian strata of new york are taken as a standard for comparison, both because of the wonderful completeness and almost undisturbed character of the rocks there, and because they have been so carefully studied. the devonian system is there fully , feet thick, with scarcely a minor subdivision missing, and it covers a wide area (one-third of the state) with many excellent outcrops. there was practically uninterrupted deposition of devonian strata in southern new york. it is doubtful if there is greater refinement of knowledge regarding the devonian or any other paleozoic system of strata anywhere else in north america. during middle to late devonian time the region from southern new england to nova scotia and the st. lawrence valley was notably disturbed by earth movements, the lands having been considerably elevated and the rocks more or less folded. the great delta deposit of late devonian time, already described as being thousands of feet thick in new york and pennsylvania, was formed by one or more streams which carved much sediment from the newly upraised lands. accompanying the uplift and folding of the rocks considerable masses of molten granite were forced into the earth's crust and some molten rock was forced to the surface, producing volcanoes. much of the granite may now be seen at the surface in various portions of the region, while deeply eroded volcanoes occur near the city of montreal. except for the disturbance of the region from new england to the st. lawrence, the devonian period seems to have closed rather quietly, with fairly widespread sea water over the land as already outlined. this is proved by the fact that the early strata of the next period mostly rest in regular order upon the undisturbed late devonian strata. for many years the term "carboniferous" period was used to designate a single period of geologic time which, in america at least, is now divided into two periods--the mississippian and pennsylvanian--corresponding, respectively, to the earliest and latest carboniferous. in regard to the relations of land and water during the mississippian period, the general statement may be made that the sea, already fairly extensive in the late devonian, continued to spread until during the second half of the mississippian, when most of the united states west of the eastern border of the appalachians (except the pacific northwest), and also the rocky mountain region through canada, were submerged. a significant physical change marked the close of the mississippian. this was the withdrawal of sea water from nearly all of the continent, the emergence of the land having been generally sufficient to allow considerable erosion. the fact that the mississippian and the next, or pennsylvanian, strata are separated by the most extensive distinct erosion surface in the whole paleozoic group of rocks is the chief reason for considering those two sets of strata to have formed during separate periods of geologic time. in eastern north america the mississippian strata vary in thickness from a few hundred feet to a maximum of about , feet in eastern pennsylvania. in the west, where the thickness is commonly several thousand feet, limestone greatly predominates. there appears to have been vigorous volcanic activity during the period from northern california to alaska. certain profound crustal disturbances marked the close of the period in western europe, resulting in upturning and folding of rocks during the process of mountain forming from ireland to germany, and from bohemia to southern france. abundant intrusions and extrusions of molten rocks accompanied the disturbances. we turn next to a consideration of the pennsylvanian period, which is of very special interest, because within the rocks of that age in north america, europe, and china occur the greatest known coal deposits. the period opened with almost all of north america dry land undergoing more or less erosion. early in pennsylvanian time marine water began to overspread the western side of the continent, especially most of the western two-thirds of the area of the united states, where strata thousands of feet thick piled up. the sea was most widespread before the middle of the period, when the relations of land and water were about as shown by figure . over the site of the appalachians and most of the eastern half of the mississippi valley area the land either stood near sea level and was often swampy or marshy, or at other times it was a little below sea level, allowing tidewater to overspread the area. such conditions alternated repeatedly, usually more or less locally, over different parts of the districts in which the great coal mines of the east are located. under such conditions strata from , to , feet thick accumulated. remarkable physical geography of this kind resulted in the growth and accumulation of vast quantities of vegetable matter which has changed into the world's greatest coal beds. similar conditions prevailed over parts of nova scotia, new brunswick, and rhode island, where strata fully , feet thick accumulated. "perhaps the most perfect resemblance to coal-forming condition is that now found on such coastal plains as that of southern florida and the dismal swamps of virginia and north carolina. both of these areas are very level, though with slight depressions in which there is either standing water or swamp condition. in both regions there is such general interference with free drainage that there are extensive areas of swamp, and in both there are beds of vegetable accumulations. in each of these areas there is a general absence of sediment and therefore a marked variety of vegetable deposit. if either of these areas were submerged beneath the sea, the vegetable remains would be buried and a further step made toward the formation of a coal bed. reelevation, making a coastal plain, would permit the accumulation of another coal bed above the first, and this process might be continued again and again." (h. ries.) but it is not necessary to assume repeated oscillations of a swamp area up and down as the only way of accounting for a succession of coal beds one above another in a given region, because a general, but intermittent, subsidence, with possibly some upward movements, would occasionally cause the prolific plant life of a swamp to be killed, after which sediment would deposit over the site. shoaling of water by accumulation of sediment would permit the development of more swamp plant life. [illustration: fig. .--map showing the general relations of land and water, including the great coal-plant swamp areas (vertical lines), in north america during the pennsylvanian period at least , , years ago. lined areas represent land. (after willis, courtesy of the journal of geology.)] in most coal-mining districts there are at least several coal beds, one above another. in illinois there are nine; in pennsylvania at least twenty; in alabama, thirty-five; and in nova scotia seventy-six, but not all are important commercially. each coal bed in such a region represents a swamp which existed in pennsylvanian time at least ten or twelve million years ago, and in which there grew a luxuriant vegetation. many individual swamps of that time were of wide extent. the famous pittsburgh bituminous coal bed represents probably the largest one of all. it extends from western pennsylvania into parts of ohio and west virginia over an area of fully , square miles. more than , square miles of it are being worked and the coal bed averages seven feet in thickness over an area of , square miles. among the various anthracite coal beds of the same age in eastern pennsylvania the mammoth bed is exceptionally thick, reaching a maximum of fifty feet or more. in order that the reader may not gain the impression that coal beds make up a very considerable bulk of the strata in coal-mining regions, we should state that, on the average, coal actually constitutes less than per cent of the containing strata. some idea of the tremendous length of the geologic ages may be gained by a consideration of the time which must reasonably be allowed for the accumulation of so many coal beds and their containing strata. it has been estimated that a luxuriant growth of vegetation would produce tons of dried organic matter per hundred years. compressed to the specific gravity of coal ( . ) this would form a layer less than two-thirds of an inch deep on an acre. during the chemical alteration of vegetable matter to coal about four-fifths of the organic matter disappears in the form of gases. on this basis, then, it would take about , years to accumulate the vegetable matter represented in a coal bed one foot thick. when we realize that the total thickness of the coal beds of the pennsylvanian system of strata in the great mining regions is commonly from to feet, we conclude that the time they represent is from , , to , , years. it seems most reasonable that the time necessary for the deposition of the containing strata must have been at least as long. it is, therefore, a fair conclusion that the pennsylvanian period lasted from , , to , , years. that the climate of the great coal age was warm (not tropical), very moist, and uniform, is borne out by such facts as the following, according to d. white: the succulent nature of the plants with their spongy leaves indicates prolific growth in moist, mild climate; lack of yearly rings of growth points to lack of distinct seasons; as in the case of many existing plants the aerial roots signify a warm, moist climate; plants of to-day nearest like the coal plants thrive best in warm, moist regions; vegetable matter at present accumulates best in temperate rather than tropical climates, because there decay is not so rapid; and the remarkable uniformity of climate over the earth is clearly indicated by finding fossil plants of almost or exactly identical types in rocks of pennsylvanian age from the polar regions to the tropics. the more remarkable plants of the great coal age time are described in the chapter on the evolution of plants (plate ). during the last (permian) period of the paleozoic era the marine waters of the west, and the alternating shallow tidewater, swamps, and near sea level lands of the east gradually gave way to dry lands, so that by the close of the period marine water covered only a small part of the southwest from oklahoma across central texas to southern california and northwestern mexico, where strata as much as several thousand feet thick formed. in the middle western part of the area of the united states, especially from northern texas to nebraska and wyoming, the climate was arid and red strata (so-called "red beds"), salt, and gypsum were extensively deposited on land and in great salt lakes or more or less cut-off arms of the sea. strata commonly from , to , feet thick were there deposited. similar conditions prevailed in parts of nova scotia, new brunswick, and newfoundland, where strata , feet thick accumulated. over the site of most of the appalachians the coal swamp conditions, with local sea incursions, continued from the preceding period, as shown by the character of the strata ( , feet thick) containing some coal. vigorous volcanic activity which, as already mentioned, began in the mississippian period from northern california to alaska continued not only through the pennsylvanian and permian but also into the early mesozoic era, as shown by the great quantities of volcanic materials associated with rocks of those ages. the permian presents a puzzling combination of climatic conditions which causes it to stand out in marked contrast against the generally mild and uniform climates of nearly all of preceding paleozoic time. most remarkable of all are the records of a great ice age during early permian time. one surprising fact is the widespread distribution of the glacial deposits in both the north and south temperate zones, and even well within the torrid zone. they are perhaps most extensive and best known in australia, south africa, india, and brazil. glacial deposits almost certainly of the same age on smaller scales occur in eastern massachusetts, southern england, eastern russia and the caucasus region. although the areas occupied by the permian glaciers, which in many cases must have been extensive ice sheets, cannot be accurately delimited, it is, nevertheless, quite certain that the ice was notably more extensively developed than it was during the great "ice age" of late (quaternary) geologic time. another surprising fact is that certain of the glaciers must have come down to, or nearly to, sea level, as shown by the direct association of marine strata with glacial deposits. thus, in southern australia at least eight beds of glacial materials (some of them to feet thick) occur within true marine strata , feet thick. a third remarkable fact is that the permian ice age, like the quaternary ice age, had interglacial epochs of relatively mild climate, as proved by the occurrences of beds of coal between certain of the layers of glacial materials in australia, south africa, and brazil. during much of permian time the climate was arid over large areas as, for example, much of the western interior of the united states, from ireland to central germany, and in eastern russia, as proved by great deposits of salt, gypsum, and red sediments. during late permian time the greatest salt beds in the world were deposited in northern germany, a well near berlin having penetrated a practically solid body of salt associated with certain potash and magnesia salts to a depth of about , feet without reaching the bottom. the occurrence of some coal beds, especially in the earlier permian rocks shows that, temporarily at least, climatic conditions must have favored luxurious growths of coal-forming plants in south africa, brazil, australia, and our own appalachian district. from the above facts we see that the permian represents a remarkable combination of very extensive glaciation, widespread aridity, and warmth and moisture favorable to prolific plant growth all in a single period of geologic time. the permian period, and, therefore, the great paleozoic era, was brought to a close by one of the most profound physical disturbances in the known history of north america. this has been called the appalachian revolution because at that time the appalachian mountain range was born out of the sea by folding and upheaval of the strata. in fact, "the appalachian revolution was one of the most critical periods in the history of the earth, and may have been the greatest of them all in its results." (c. schuchert). mountains were brought forth in all the continents, including australia. all of the mountains which were formed late in the paleozoic have since been profoundly affected by erosion, and the only ones (e.g., appalachians) which now show considerable altitudes are those which have been rejuvenated by relatively (geologically) recent earth movements. we shall now turn our attention to the origin of the appalachian range. all through the vast time (probably fully , , years) of the paleozoic era a large land mass was remarkably persistent along the eastern side of north america. this land, which has been called "appalachia," had its western boundary approximately along the eastern border of the sites of the appalachian range and the western part of new england. it extended east of the present coast line at least to the border of the continental shelf from to miles out. concerning the actual altitude and topography of appalachia we know little or nothing, but the tremendous quantities of sediment derived from its erosion show that it was high enough during nearly all of its history to undergo vigorous erosion. barring certain minor oscillations of level, the region just west of appalachia was mostly occupied by sea water throughout much of paleozoic time, and sediments derived from the erosion of appalachia were laid down layer upon layer as strata upon that sea bottom. in general, the coarsest and greatest thickness of sediments accumulated relatively near the land, while finer materials, in thinner sheets, deposited well out over much of the eastern mississippi valley area in the shallow seas which were there so commonly present. by actual measurement we know that the thickness of strata deposited over the site of the appalachians was at least , feet. since these latter strata are mostly of comparatively shallow sea-water origin, as proved by coarseness of grain of material, ripple marks, fossil coral reefs, etc., we are forced to conclude that this marginal sea bottom gradually sank while the process of sedimentation was in progress. otherwise we cannot possibly explain the great pile of strata of shallow water origin. the very weight of accumulating strata may either have aided or actually caused the sinking of the long, relatively narrow trough. finally, toward the close of the paleozoic era, sinking of the marginal sea floor and deposition of sediments gave way to a yielding of the earth's crust by a great force of lateral compression, causing the strata to be thrown into folds well below the surface and more or less fractured in their upper portion. thus, along the eastern side of the site of the great interior paleozoic sea, the appalachian mountains rose out of what for millions of years had been a long, narrow, sinking sea floor. there was more or less folding from the gulf of st. lawrence to central alabama. figure diagrammatically represents the principal stages in the history of the appalachian range. while the most pronounced earth disturbance occurred through the long appalachian belt, the whole eastern side of the continent was profoundly affected. thus the mississippi valley area east of the great plains was considerably upraised never again to be submerged except along the gulf coast, and an eastern interior sea has never since overspread the region which was repeatedly sea-covered during paleozoic time. chapter xv medieval earth history (_mesozoic era_) what was the condition of north america during the first or triassic period of the mesozoic era, approximately or million years ago? as a result of the appalachian revolution the sea was excluded from all the land except along much of the western side from southern california to parts of alaska. on this western side of the continent the appalachian revolution had little or no effect and the permian conditions continued, essentially without change through the triassic. the triassic strata up to , feet thick are there of typical marine origin. in british columbia and alaska there was much igneous activity. throughout much of the rocky mountains and great plains region of the western united states there are extensive deposits of red sediments (so-called "red beds"), containing layers of salt and gypsum, from to , or more feet thick. these strata commonly rest in regular order on permian red beds, so that conditions of deposition of permian time continued through triassic time, that is continental deposits formed mostly in salt lakes, fresh lakes, along stream courses, and on land in part by the action of wind. [illustration: fig. .--map showing the general relations of land and water in north america during the triassic period. lined areas represent land; vertical-lined areas, basins in which continental deposits formed. (based upon map by willis; courtesy of the journal of geology.)] in the eastern half of north america there is no record of accumulation of any marine strata whatever, because, as a result of the appalachian revolution, the land was brought well above sea level. there was, however, deposition of a remarkable series of nonmarine strata in several long, narrow, troughlike depressions whose trend was parallel to, and just east of, the main axis of the newly formed appalachian range. these troughs lay between the appalachians and the very persistent old land mass called appalachia which we have already described. the facts that these troughs are truly down-warps; that they so perfectly follow the trend of the appalachian mountain folds; and that the strata in them are of late triassic age, make it certain that they were formed by a great lateral pressure which must have been a continuation of the appalachian revolution. thus the appalachian mountains continued to grow well into the triassic period, and, while the paleozoic strata were being folded, the surface of old appalachia (including part of the taconic mountain region) was down-warped to form the troughs in which the late triassic strata accumulated. one trough extended through the connecticut valley; another (the largest) from southeastern new york through northern new jersey, southeastern pennsylvania, maryland, and into virginia; while several smaller ones occurred in virginia and north carolina. the down-warps or troughlike basins were very favorably situated for rapid accumulation of thick sedimentary deposits because of their position just between large, high land masses which were being vigorously eroded. the sediments derived from the erosion of the young appalachians were especially abundant because of the vigorous wearing down of the newly formed high mountains. a thickness of from , to fully , feet of mostly red sandstones and shales accumulated in these down-warps, the character and great thickness of the strata strongly pointing to gradual down-warping as the deposition of the sediments went on. it is often stated that these strata were formed in estuaries, but, in the northern areas, at least from massachusetts to maryland, many of the layers show ripple marks, sun cracks, rain-drop pits, fossil plants, and fossil bones and tracks of land reptiles. such strata may well have formed in very shallow water, such as river-flood plains or temporary lakes, where changing conditions frequently allowed the surface layers to lie exposed to the sun. [illustration: fig. .--block diagram of the region westward from new york city and vicinity, showing the main relief features, the underground relations of rocks of widely different ages, and the relation of the relief to the rock formations. (part of larger drawing by a. k. lobeck.)] during the time of the accumulation of the late triassic strata in the down-warp basins there was considerable igneous activity, as proved by the occurrence of sheets of igneous rock within the body of strata. in some cases true lava flows with cindery tops were forced out on the surface and then buried under later sediments, while in other cases the sheets of molten rock were forced up either between the strata or obliquely through them, thus proving their intrusive character. as a result of subsequent erosion, these very resistant lava masses often stand out conspicuously as relief features. perhaps the most noteworthy example is the great layer of such intrusive igneous rock, part of which outcrops for seventy miles mostly as a bold cliff forming the famous palisades of the hudson, near new york city. during the process of cooling and solidification of the molten mass there was contraction which expressed itself by breaking the rock mass into great, crude, nearly vertical columns, and hence the origin of the name "palisades." the cliff character of the outcrop is due to the fact that the lava is much more resistant to erosion than the sandstone above and below it. in the connecticut valley of massachusetts a layer of lava several hundred feet thick boldly outcrops, forming the crest of the well-known mount tom-mount holyoke range. the close of the triassic period was marked by enough uplift to leave the whole eastern two-thirds of the continent dry land undergoing erosion. the triassic deposits of the atlantic coast are much broken up into large fault blocks, and this faulting probably took place as a result of the crustal disturbances toward the end of the period. in the west the triassic conditions seem to have continued without much change into the next (or jurassic) period. during the jurassic period the relations of land and water in north america were very simple. in the earlier jurassic all was dry land except portions of the western fringe of the continent from southern california to alaska, where marine strata , to , feet thick accumulated. late in the period the conditions were the same, except for a long, narrow arm of the sea or mediterranean which extended from the arctic ocean southward across the site of the rocky mountains to arizona. there is no evidence for the existence of anything like real mountains anywhere on the continent during the period. [illustration: fig. .--structure section showing profile and underground relations of rocks across the connecticut valley (through mount tom) of massachusetts. js and jl are sandstone strata, with included lava sheets (in black) resting upon paleozoic rocks on either side. the rocks have been notably tilted and faulted. (after emerson, u. s. geological survey.)] profound crustal disturbances marked the close of the jurassic period in the western part of the continent. strata which had accumulated to great thickness during millions of years of time, mainly over the sites of the sierra nevada and cascade mountains, finally yielded to a tremendous force of lateral compression, especially in the sierra region, and were folded, crumpled, and upraised. thus the sierra-cascade district was originally built up into a high mountain range. since that time the sierras have been much cut down by erosion and they have been rejuvenated by faulting and tilting of the great earth block. the cascade range from northern california into british columbia was apparently not so profoundly raised, and its present height is mainly due to subsequent volcanic activity. the rocks of the klamath mountains of northwestern california, and of the humboldt range of nevada, were also folded at that time. during the mountain-making disturbances on the western side of the continent great quantities of molten granite were forced up into the lower portions of the folding strata. because of profound subsequent erosion this granite is now widely exposed as, for example, in the great walls of the yosemite valley. during the earlier half of the last period (the cretaceous) of the mesozoic era, sea water spread from mississippi northwestward to the site of denver and southward over texas and much of mexico. at the same time much of the western margin of the continent from alaska to california was submerged. all the rest of the continent was land. during this time sediments accumulated on low lands just east of the site of the present rocky mountains, and also east of the appalachians, as proved by the numerous fossils of land plants found in these deposits. [illustration: fig. .--map showing the general rotations of land and water in north america during later cretaceous time, several million years ago. lined areas represent land; vertical lines, mainly continental deposits. (principal data from a map by willis, published in the journal of geology.)] as cretaceous time went on the marine waters gradually spread until the whole atlantic and gulf coastal plain regions from long island, new york, to mexico became submerged under marine water, and a wide arm of the sea, or great mediterranean, spread from texas north to the mouth of the mackenzie river. the gulf of mexico was thus directly connected with the arctic ocean. this great interior sea was nowhere connected with the pacific ocean, though portions of the pacific border of the continent were submerged. this vast interior sea was not only the largest of any which reached well into the continent since the mississippian period of the paleozoic era, but it was the last body of marine water which ever extended well into the continent. it should be stated that the later cretaceous was also a time of unusually widespread submergence of the continents, when most of southern europe and southeastern asia, as well as about one-half of both africa and south america were submerged. over much of the site of the rocky mountains during the late cretaceous there were low lands receiving continental deposits, and extensive marshes supporting prolific vegetation were common. much of this vegetable matter became buried, and has since been converted into workable coal. the maximum thickness of strata accumulated during all of cretaceous time over the atlantic coastal plain area was about , feet; over the gulf coastal plain region fully , feet; over the western interior , to , ; and over parts of the pacific border , to , feet, as in california. the last-named figures are truly phenomenal, representing a thickness about equal to the total thickness of all the strata accumulated during the whole paleozoic era (seven periods) and piled up in the appalachian mountain region. this great deposit of strata of mostly early cretaceous age is readily accounted for when we realize that these sediments, which accumulated in the marginal sea bottom, were derived from the very rapidly eroding, newly formed lofty sierra nevada range. [illustration: fig. .--sketch of a mountain range along skolat creek, alaska, showing tertiary lava beds resting upon deeply eroded tilted limestones and lavas of late paleozoic (carboniferous) age. the present topography has been produced by erosion since the tertiary lavas flowed out. (after u. s. geological survey.)] especially in alabama and texas the cretaceous system is remarkable for its richness in chalk deposits. in alabama a widespread formation of late cretaceous age, about , feet thick, contains much nearly pure white chalk, and in texas a similarly constituted formation of early middle cretaceous age is from , to , feet thick. these chalk deposits consist almost wholly of carbonate of lime shells or very tiny single-celled animals which accumulated under exceptionally clear sea water which spread over those parts of alabama and texas where the chalk now occurs. here again we have a bit of evidence supporting the fact of very long geologic time. think of how long it must have taken for the tiny (even microscopic) shells to form a widespread layer of chalk nearly a mile thick! the close of the cretaceous period, or what is the same, the close of the mesozoic era, was marked by some of the grandest crustal disturbances in the known history of the earth. in fact, it is not known that the western hemisphere was ever affected by more profound and widespread mountain-making disturbances than those which took place toward the close of the mesozoic era, and continued into the succeeding tertiary period. these disturbances were of three kinds: folding of strata, volcanic activity, and renewed uplift of old mountains without folding of the rocks. greatest of all was the "rocky mountain revolution," during which the thick strata, which accumulated during the paleozoic and mesozoic eras over the site of the rockies, yielded to vigorous deformation when they were more or less folded and dislocated from alaska to central america. this was in truth the birth of the rocky mountains, although their existing altitude and configuration have, to a very considerable degree, resulted from later uplift and erosion. in the northern united states and southern canada the rocky mountain strata, up to over , feet thick, were most severely folded and fractured, forming a range which quite certainly was fully , feet high. in this district a great thrust fault, hundreds of miles long, developed, and rocks as old as the proterozoic were shoved at least seven miles, and probably as much as twenty miles, westward, over cretaceous and other rocks much later than the proterozoic. at the same time the andes mountains throughout south america were notably upraised and the rocks folded. the second type of physical disturbance was volcanic activity which took place on a tremendous scale, and which appears to have started as a direct accompaniment of the rocky mountain revolution. this igneous activity took place not only in the rocky mountains but also westward to and in the sierra-cascade range, as well as in the mountains of western british columbia and alaska. this activity continued well into the succeeding cenozoic era, and it is more fully considered in the next chapter. the third type of crustal disturbance took place on a large scale when the appalachian mountains, which had been almost wholly planed away by erosion during mesozoic time, were reelevated from , to , feet by an uplifting force not accompanied by folding. all or nearly all of new york and new england, as well as much of southeastern canada, were similarly upraised at the same time. this notable uplift of so much of eastern north america is a matter of great importance because the major relief features of that area have been produced by erosion or dissection of the upraised surface since late mesozoic or early cenozoic time. in view of the fact that this work of erosion took place almost wholly during the cenozoic era, it will be discussed in the next chapter. in conclusion, brief mention may be made of the kind of climate of the mesozoic era. as shown by the character and distribution of fossil plants and animals, the mesozoic climate was in general mild and rather uniform over the earth, but with some distinction of climatic zones. such distinction of climatic zones is unknown for the paleozoic era, while it was notably less than at present. chapter xvi modern earth history (_cenozoic era_) since the cenozoic era is the last one of geologic time, it will be of particular interest to trace out the main events which have led up to the present day conditions, especially in north america. both because of the recency of the time and the unusual accessibility of the rocks, which are mostly at or near the surface, our knowledge of the cenozoic era is exceptionally detailed and accurate. it will, therefore, be more necessary than ever to select only the very significant features of this history for our brief discussion. during the first half of the tertiary period portions only of the atlantic coastal plain were submerged under shallow water, but soon after the middle of the period (miocene epoch) the sea spread over practically the whole atlantic coastal plain area from martha's vineyard south to and including florida. during the late tertiary the marine waters had become greatly restricted, and by the close of the period the sea was entirely excluded from the atlantic seaboard. the total thickness of these tertiary strata is less than , feet, and they all tilt downward gently toward the sea. the strata consist mostly of unconsolidated sands, gravels, clays, marls, etc. the gulf coastal plain area from florida through texas and south through eastern mexico was largely overspread by the sea during most of tertiary time, except the latest. during early tertiary time an arm of the gulf reached north to the mouth of the ohio river. late in the period but little of the gulf plain was submerged, and at its close sea water was wholly excluded. on the gulf coast the tertiary strata from , to , feet thick are also mainly sands, gravels, clays, and marls. they are commonly rich in fossils, and they show a gentle tilt downward toward the gulf. throughout tertiary time local portions of the pacific border of the continent were submerged, this having been especially true of portions of california, oregon, and washington. in spite of the very restricted marine waters, the tertiary strata of the pacific coast, especially in california, are remarkably thick, , to , feet being common, while the maximum thickness is fully , feet. such great thicknesses are readily explained when we realize that erosion was notably speeded up by pronounced uplifts resulting from crustal disturbances toward the close of the preceding period, and again in the midst of the tertiary period itself. to summarize the tertiary relations of sea and land for north america we may say that only local portions of the continental border ever became submerged, and that, by late tertiary time, practically the whole continent was a land area. at the close of the period the continent was, as we shall see, even larger than now because the continental shelves of the ocean were then also largely above water. [illustration: fig. .--map showing the general relations of land and water in north america during part of the middle tertiary period. (after willis, courtesy of the journal of geology.)] the whole of the cenozoic era, including both the tertiary and quaternary periods, has been a time of profound crustal disturbances throughout much of the continent, certain of these movements having continued right up to the present time, with positive evidence that some of them are still continuing. these great movements have included notable foldings of strata, uplifts without folding, faulting, and igneous activity, the whole effect having been to greatly increase the general altitude and ruggedness of the continent. in fact, north america is not known ever to have been at once higher, broader, and more rugged than it was very late in the tertiary, or early in the quaternary, period. since that time the only notable change (barring the great ice age and its effects) has been a restriction of the area of the continent to its present size by spreading of sea waters over the borders of the continent, that is over the continental shelves. we shall now rather systematically consider the more profound earth changes which have affected the continent, producing the existing major relief features, from west to east. the "coast range revolution" took place in the midst of the tertiary period. over the site of the coast ranges, strata had accumulated, especially during cretaceous and earlier tertiary times, to a thickness of thousands of feet. in middle tertiary time these strata were subjected to a mountain-making force of compression and more or less folded, faulted (fractured), and uplifted into the coast range mountains. some portions of the range were intensely folded and faulted and upraised many thousands of feet, while other portions were only moderately folded and uplifted. it is an interesting fact that the great san francisco earthquake rift or fault originated at this time. it was a renewed, sudden movement of a few feet along this fault which caused the disastrous earthquake of . still other considerable earth movements took place in the coast range region during late tertiary and quaternary times, as, for example, uplift without folding, as proved by distinct sea-cut terraces at altitudes of more than a thousand feet, like those north of san francisco and south of los angeles. a moderate amount of still later subsidence has caused the development of san francisco bay. the large islands off the coast of southern california have in very recent geologic time (probably quaternary) been cut off from the mainland by sinking of the land. [illustration: plate .--(_a_) part of the mammoth hot springs terrace in the yellowstone park. the view shows the deposit with boiling water flowing over it. the water enters the earth back on the mountain, travels underground in contact with hot lava, rises through limestone, from which the boiling water takes into solution much carbonate of lime which is deposited when the water reaches the surface. (_photo by jackson, u. s. geological survey._)] [illustration: plate .--(_b_) view across part of crater lake, oregon. this great hole, , to , feet deep and miles in diameter and now partly filled with a lake , feet deep, was formed by a subsidence of the top of a once great cone-shaped volcano fully , feet high above the sea. the high rock in the distance rises , feet above the lake which is over , feet above sea level. the island is a small volcano of recent origin. (_photo by russell, u. s. geological survey._)] [illustration: plate .--(_a_) detailed view of part of the very oldest known (archeozoic) rock formation of the earth. the rock is distinctly stratified and represents sands and muds deposited layer upon layer upon a sea floor at least , , years ago. the sands and muds first consolidated into sandstone and shale below the earth's surface. then, under conditions of heat, moisture, and pressure, they were notably altered, mainly by crystallization of minerals, and raised high above sea level. finally the strata were laid bare by erosion. (_photo by the author._)] [illustration: plate .--(_b_) a twisted mass of stratified archeozoic limestone surrounded by granite in northern new york. the limestone was enveloped in the granite while it was being forced in molten condition into the earth's crust. (_photo by the author._)] the sierra nevada range, which originated by intense folding of rocks late in the jurassic period, underwent profound erosion until about the middle of the tertiary period, by which time it had been cut down to a range of hills or low mountains. then the great fault (fracture) previously described began to develop along the eastern side. as a result of many sudden movements along this fault, which is hundreds of miles long, the vast earth block has been tilted westward with a very steep eastern face and a long, more gradual western slope, the crest of the fault block forming the summit of the range. the amount of nearly vertical displacement along this fault has been commonly from , to , feet, and, in spite of considerable erosion of the top of the fault block and accumulation of sediment at its eastern base, the modified fault face now usually stands out boldly from , to , feet high. as an evidence that this movement of faulting has not yet ceased we may cite the inyo earthquake of , when there was a sudden renewal of movement of ten to twenty-five feet along this fault for many miles. since the great sierra block began to tilt, the many mighty canyons, like yosemite, hetch-hetchy, king's river, and feather river, have been carved out by the action of streams, in some cases aided by former glaciers. king's river canyon has been sunk to a maximum depth of , feet in solid granite solely by the erosive action of the river! the cascade mountains, too, were reduced to nearly a peneplain condition by late tertiary time when they began to be rejuvenated by arching or bowing of the surface unaccompanied by great faulting or fracturing, and many canyons, like that of the columbia river, have since been carved out. mention should now be made of the vigorous volcanic activity which took place in the cascade and sierra nevada ranges. most of this activity occurred during tertiary time (particularly in the latter part) and it has continued with diminishing force practically to the present time. in california streams of lava buried many gold-bearing river gravels which have yielded rich mines. many well-known mountain peaks, such as shasta, lassen, pitt, hood, and rainier, from northern california to washington, are great volcanic cones which date from tertiary time, and which are now mostly inactive. that this volcanic activity has not yet altogether ceased is shown by renewed eruptions of mount lassen (or lassen peak, altitude , feet) in northern california. since the beginning of this renewed activity in , several hundred outbursts have occurred. no molten rock has flowed out, but large quantities of rock fragments, dust and steam have been erupted, in many cases forming great clouds two or three miles high over the top of the mountain (plate ). at this writing (october, ), mount lassen is still showing vigorous activity. at cinder cone, only ten miles from mount lassen, there were two eruptions of cinders and a considerable outpouring of lava within the last years. still other very recent cinder cones occur in southeastern california and arizona. [illustration: fig. .--sketch map showing the distribution of volcanic rocks of cenozoic (mostly tertiary) age in western north america. only one volcano (mount lassen, california) is now active in the united states proper, but a number are more or less active in mexico and central america. (data from willis, u. s. geological survey.)] one of the greatest lava fields in the world forms the columbian plateau between western wyoming (including the yellowstone national park) and the cascade mountains from northeastern california to northern washington. it covers fully , square miles and is really considerably larger than shown on the map because the lava in parts of the plateau region are covered by very recent sedimentary materials. the great lava fields of the deccan, india, and of the plateau region of western mexico are comparable in size to the columbian field and these lava fields are all of the same age. in the columbian plateau most of the lava was poured out during later tertiary time. sheets of molten rock, averaging fifty to one hundred feet in thickness, spread out over various parts of the region and piled up by overlapping layers one over another until the lava plateau more than a mile high was built up. many hills and low mountains were completely buried under the molten floods, and in other places the liquid rock masses flowed against the higher mountains. "for thousands of square miles the surface is a lava plain which meets the boundary mountains as a lake or sea meets a rugged and deeply indented coast.... the plateau was long in building. between the layers are found in places old soil beds and forest grounds and the sediments of lakes.... so ancient are the latest floods in the columbia river basin that they have weathered to a residual yellow clay from thirty to sixty feet in depth, and marvelously rich in the mineral substances on which plants feed. in the snake river valley the latest lavas are much younger (quaternary). their surfaces are so fresh and undecayed that here the effusive eruptions may have continued to within the period of human history." (w. h. norton.) many of the lava layers are plainly visible where the columbia river has cut its great gorge or canyon. the snake river in places has sunk its channel several thousand feet into the lava plateau without reaching underlying rock. both north and south of the columbian plateau there was also much volcanic activity in the rocky mountain region during tertiary time. a single formation in colorado consists mostly of volcanic "ash" or dust over , feet thick. there was also much volcanic activity over the colorado plateau area of southern utah, new mexico, and arizona. the volcanoes there exhibit all stages from those which are very recent and practically unaffected by erosion to others which have been completely cut away with the exception of the cores or "volcanic necks." during the second half of the tertiary period the whole region known as the great basin, between the sierra nevada mountains of california and the wasatch mountains of utah, began to be affected by profound faulting or fracturing and tilting of portions of the earth's crust. the two largest faults, one on the western side of the wasatch range and the other on the eastern side of the sierra range, are each hundreds of miles long. each of these ranges owes most of its present altitude to the uptilting of great fault blocks, and most of the many nearly north-south basin ranges of nevada and utah are in reality recently tilted fault blocks. turning now to the colorado plateau, studies have shown that region to have been more or less periodically raised fully , feet since the beginning of tertiary time, but because of profound erosion in the meantime its present altitude is only , to , feet. during late tertiary time the land stood at a much lower level than to-day, so that, practically during the last period (quaternary) of geologic time, the region has been elevated to its present position. as a direct result of this profound rejuvenation the colorado river has had its erosive activity tremendously increased, and it has carved out the mightiest of all existing canyons--the grand canyon. the work of deepening and widening the canyon is still proceeding at a rapid geologic rate. as we have learned, the rocky mountains and many of its subsidiary ranges were formed by folding and uplift of strata toward the close of the mesozoic era (cretaceous period). during much of tertiary time the newly formed mountains had been considerably reduced by erosion. then, late in the tertiary period, much of the rocky mountain region, as well as much of the great plains area just east of the mountains, became rejuvenated by differential uplift without any notable folding of strata. we can tell that this general uplift amounted to at least several thousand feet because definite formations of relatively late tertiary strata, originally horizontally deposited under inland bodies of water, gradually rise so that at the base of the front range of the rockies they are fully , feet higher than they are miles or more farther east. thus, the original folding and faulting of the rockies, tertiary volcanic activity, late tertiary rejuvenation, and subsequent erosion account for the present altitude and relief features of the great rocky mountain system. portions of the rejuvenated great plains region have been notably dissected by erosion since the late tertiary, this being particularly true of the so-called "bad lands," especially in parts of wyoming and south dakota, where mostly relatively soft tertiary strata have been cut to pieces. turning our attention now to the eastern half of the continent we find that all, or nearly all, of it was more or less raised toward the close of the tertiary period. practically the whole mississippi valley east of the great plains, as well as much of the country to the north in canada, was elevated some hundreds of feet and the streams have since the late tertiary uplift (except where the land was ice-covered during the ice age) been at work sinking their channels below the newly upraised surface. as already pointed out, the lowlands of the atlantic and gulf coastal plains were mostly submerged under the sea during early middle tertiary time. by the close of the period they had emerged practically to their present positions, and they have been only moderately affected by erosion. we have still to explain the existing topography or relief of a large and important part of eastern north america, including the whole of the appalachian mountains, allegheny plateau, piedmont plateau, new york, new england, and the canadian region to the north. as a starting point in this discussion we should recall the fact that, after the great appalachian mountain revolution toward the close of the paleozoic era, the predominant geologic process which affected the region under consideration was erosion throughout the succeeding mesozoic era. by about the close of the mesozoic (cretaceous period) the whole region, with some local exceptions, has been worn down to a comparatively smooth plain (peneplain) not far above sea level. local exceptions were mainly in the new york and new england region as, for example, some of the higher parts of the adirondack and white mountains, mount monadnock in southern new hampshire, and mount greylock in western massachusetts. these and other masses rose rather conspicuously above the general level of the great plain of erosion commonly called the "cretaceous peneplain" because it is believed to have been well developed by the close of that period. the uplift of the vast cretaceous peneplain about the beginning of the cenozoic era (tertiary period) was an event of prime importance in the recent geological history of eastern north america because it was literally the initial step in bringing about nearly all of the existing major relief features of the appalachian-new york-new england-st. lawrence region. the amount of uplift (unaccompanied by folding) of the peneplain was commonly from a few hundred to a few thousand feet with the greatest amount in general along the main trend of the appalachians. the fact should be emphasized that nearly all the principal topographic features of the great upraised region have been produced by dissection (erosion) of the uplifted peneplain surface. thus nearly all the valleys, small and large, including those of the st. lawrence, hudson, mohawk, connecticut, and susquehanna, have been carved out by streams since the uplift of the great peneplain. the streams which flowed upon the old low-lying peneplain surface meandered sluggishly over deep alluvial or flood-plain deposits, and their courses were little if any determined by the character and structure of the underlying rocks, because, with few exceptions, all rocks were worn down to the general plain level. the uplift of the peneplain, however, caused great revival of activity of erosive power by the streams, the larger ones of which soon cut through the loose superficial alluvial deposits and then into the underlying bedrock. thus the large, original streams had their courses well determined in the overlying deposits, and when the underlying rocks were reached the same courses had to be pursued entirely without reference to the underlying rock character and structure. such streams are said to be "superimposed" because they have, so to speak, been let down upon and into the underlying rock masses. as professor berkey has well said: "the larger rivers, the great master streams, of the superimposed drainage system, in some cases were so efficient in the corrosion of their channels that the discovery of discordant structures (in the underlying rocks) has not been of sufficient influence to displace them, or reverse them, or even to shift them very far from their original direct course to the sea. they cut directly across mountain ridges because they flowed over the plain out of which these ridges have been carved, and because their own erosive and transporting power have exceeded those of any of their tributaries or neighbors." fine examples of such superimposed streams which are now entirely out of harmony with the structure of regions through which they flow are the susquehanna, delaware, and hudson. thus the susquehanna cuts across a whole succession of appalachian ridges while, in accordance with the same explanation, the delaware cuts through the kittatiny range or ridge at the famous delaware water gap. the ridges are explained as follows: while the great master streams were cutting deep trenches or channels in hard and soft rock alike, numerous side streams (tributaries) came into existence and naturally mostly developed along belts of weak, easily eroded rock parallel to geologic (folded) structure. thus the appalachian valleys have been, and are being, formed, while the ridges represent the more resistant rock formations which have more effectually stood out against erosion. the lower hudson river flows at a considerable angle across folded formations above the highlands, after which it passes though a deep gorge which it has cut into the hard granite and other rocks of the highlands. the simple explanation is that the hudson had its course determined upon the surface of the upraised cretaceous peneplain, and that it has been able to keep that course in spite of discordant structure and character of the underlying rocks. in a similar manner we may readily account for the passage of the connecticut river through a great gap in the holyoke ridge or range of hard lava in western massachusetts. before leaving this part of our discussion we shall briefly present some evidence showing that the new york-new england-st. lawrence region at least must have been considerably higher shortly before the ice age (quaternary period). an old channel of the hudson river has been traced about miles eastward beyond the present mouth of the river and it forms a distinct trench under the shallow sea in the continental shelf. even in the hudson valley, many miles above new york city, the bedrock bottom of the river lies hundreds of feet (near west point, feet) below sea level. obviously this submerged channel must have been cut when the land in the general vicinity of new york city was fully , feet higher than at present. that the land thus stood higher late in the tertiary and possibly early in the quaternary periods is proved as follows: ( ) because most of tertiary time must have been needed for the river to erode such a deep valley after the initial uplift of the peneplain about the beginning of the period; and ( ) because glacial deposits of quaternary age filled the former channel to a considerable depth. the valleys of the coast of maine, and the submerged lower st. lawrence valley (gulf of st. lawrence), in a similar way lead us to conclude that the region farther north was also notably higher just before the ice age. in the eastern hemisphere early in the tertiary period a great submergence set in and marine waters spread over much of western and southern europe, northern africa, and southern asia. the sites of the himalayas, alps, pyrenees, apennines and other mountains were then mostly submerged. a very remarkable marine deposit, made up almost wholly of carbonate of lime shells of a single-celled animal called nummulites, formed on the floor of this vastly expanded early tertiary mediterranean. this rock attains a thickness of several thousand feet. it is doubtful if any other single formation made up almost entirely of the shells of but one species is at once so widespread and thick. in the alps this remarkable marine deposit may be seen , feet above sea level, and in tibet fully , feet. much of the rock in the egyptian pyramids was quarried from this formation. later in the tertiary in eurasia and africa the marine waters gradually became very restricted, so that by the close of the period the relations of land and sea were not strikingly different from the present, although northwestern europe, like northeastern north america, was notably higher just before the ice age than it is to-day. eurasia witnessed tremendous crustal disturbances during the middle and later tertiary time when, due to intense folding and uplift of great zones, the himalayas, caucasus, alps, pyrenees, apennines, and other great ranges were formed. the crustal disturbance was most remarkable in the region of the alps, where the movement resulted in "elevating and folding the tertiary and older strata into overturned, recumbent, and nearly horizontal folds, and pushing the southern or lepontine alps about sixty miles (over a low angle fault fracture) to the northward into the helvetic region. erosion has since carved up these overthrust sheets, leaving remnants lying on foundations which belong to a more northern portion of the ancient (early tertiary) sea. most noted of these residuals of overthrust masses is the matterhorn, a mighty mountain without roots, a stranger in a foreign geologic environment." (c. schuchert.) the last period of geological time--the quaternary--was ushered in by the spreading of vast sheets of ice over much of northern north america and northern europe, and this ranks among the most interesting and remarkable events of known geological time. on first thought the former existence of such vast ice sheets seems unbelievable, but the ice age occurred so short a time ago that the records of the event are perfectly clear and conclusive. the fact of this great ice age was discovered by louis agassiz in , and fully announced before the british scientific association in . for some years the idea was opposed, especially by advocates of the so-called iceberg theory. now, however, no important event of earth history is more firmly established, and no student of the subject ever questions the fact of the quaternary ice age. some of the proofs of the former presence of the great ice sheet are as follows: ( ) polished and striated rock surfaces which are precisely like those produced by existing glaciers, and which could not possibly have been produced by any other agency; ( ) glacial bowlders or "erratics" which are often somewhat rounded and scratched, and which have often been transported many miles from their parent rock ledges (plate ); ( ) true glacial moraines, especially terminal moraines, like that which extends the full length of long island and marks the southernmost limit of the great ice sheet; and ( ) the generally widespread distribution over most of the glaciated area of heterogeneous glacial débris, both unstratified and stratified, which is clearly transported material and typically rests upon the bedrock by sharp contact. the best known existing great ice sheets are those of greenland and antarctica, especially the former, which covers about , square miles. this glacier is so large and deep that only an occasional high rocky mountain projects above its surface, and the ice is known to be slowly moving outward in all directions from the interior to the margins of greenland. along the margins, where melting is more rapid, some land is exposed, and often the ice flows out into the ocean where it breaks off to form large icebergs. [illustration: fig. .--map of north america showing the area buried under ice during the great ice age of the quaternary period; the three great glacial centers; and the extent of mountain glaciers in the west. (after u. s. geological survey.)] the accompanying map shows the area of nearly , , square miles of north america covered by ice at the time of maximum glaciation, and also the three great centers of accumulation and dispersal of the ice. the directions of flow from these centers have been determined by the study of the directions of many thousands of glacial scratches on rock ledges. the labradorean (or laurentide) glacier spread out , miles to the south to long island and near the mouth of the ohio river. the vast keewatin glacier sent a great lobe of ice nearly as far south, that is into northern missouri. "one of the most marvelous features of the ice dispersion was the great extension of the keewatin sheet from a low flat center westward and southward over what is now a semiarid plain, rising in the direction in which the ice moved, while the mountain glaciers on the west (cordilleran region), where now known, pushed eastward but little beyond the foot-hills." (chamberlin and salisbury.) the labradorean and keewatin ice sheets everywhere coalesced except in two places. one of these is an area of about , square miles mostly in southwestern wisconsin. in spite of several ice invasions during the ice age, this area, hundreds of miles north of the southern limit of the ice sheets, was never ice-covered. there is a total absence of records of glaciation within this area, and so we here have an excellent sample of the kind of topography which prevailed over the northern mississippi valley just before the advent of the ice. a much smaller, nonglaciated area occurs in northeastern missouri near the southern limit of ice extension. the cordilleran ice sheet was the smallest of the three, and it was probably not such a continuous mass of ice, the higher mountains projecting above its surface. a surprising fact is that neither this ice sheet nor any other overspread northern alaska, which is well within the arctic circle, during the ice age. more than likely the temperature was low enough, but precipitation of snow was not sufficient to permit the building up of a great glacier. at the same time that nearly , , square miles of north america were ice-covered, about , square miles of northern europe were buried under ice which spread from the one great center over scandinavia southwest, south, and southeast over most of the british isles, well into germany, and well into russia. in both north america and europe the high mountains, well south of the great glacier limits, especially the sierras, rockies, alps, pyrenees, and caucasus, supported many large local glaciers in valleys which now contain none at all or only relatively small ones. records of glaciation, such as glacial scratches, bowlders, lakes, etc., occur high up in the white and green mountains, adirondacks, catskills, and the berkshire hills, thus proving that the ice must have been at least some thousands of feet thick over new england and new york. we have good reason to believe that even the highest summits, except possibly in the catskills, from , to over , feet above sea level, were completely submerged under the ice. on top of a mountain of archeozoic granite nearly , feet in altitude, facing the st. lawrence valley in northern new york, the writer has found many fragments of sandstone which were picked off by the ice in the low valley, moved southward a good many miles, and uphill several thousand feet to the top of the mountain. the reader may wonder how a great glacier at least a mile thick in northern new york could have thinned out to disappearance within the short distance to the southern border of the state, but observations on existing large glaciers show that it is quite the habit for them to thin out very rapidly near their margins, thus producing steep ice fronts. the fact that glacial ice flows as though it were a viscous substance is well known from studies of valley glaciers in the alps and alaska, and the great ice sheet of greenland. a common assumption, either that the land at one of the great centers of ice accumulation during the ice age must have been many thousands of feet higher, or that the ice must there have been immensely thick, in order to permit ice flowage so far out from the center, is not necessary. viscous tar slowly poured upon a level surface will gradually flow out in all directions, and at no time need the tar at the center of accumulation be very much thicker than elsewhere. the movement of glacial ice from the great centers of dispersal during the ice age was much the same in principle, only in the case of the glaciers the accumulations of snow and ice were by no means confined to the immediate centers. the fronts of the vast ice sheets, like those of ordinary valley glaciers, must have undergone many advances and retreats of greater or less consequence. in the northern mississippi valley, and also in europe, there is positive proof for five or six important advances and retreats of the ice which gave rise to the true interglacial stages. the strongest evidence is the presence of successive layers of glacial (morainic) débris piled one upon another, a given layer often having been oxidized, eroded, and even covered with plant life before the next or overlying layer was deposited. such is the condition of things throughout much of iowa, where wells sunk into the glacial deposits commonly pass through layers of partly decomposed vegetable matter at depths of from to feet. near toronto, canada, the finding of warm climate plants between two glacial deposits proves that the climate there during an interglacial stage was much like that of the southern states to-day. during the great interglacial stages the vast glaciers were notably restricted in size, and in some or possibly all, cases they may have wholly disappeared from the continent. in former years there was a tendency to ascribe mighty erosive power to the vast slow-moving ice sheets, but to-day scarcely any geologist would hold that the ice really produced large valleys solely by ice erosion, or that mountains were notably cut down. throughout the glaciated region, especially toward the north, the deep preglacial residual soils and rotten rocks were nearly all scoured off by the passage of the ice. that the ice, where properly shod with rock fragments, actually eroded to at least little depths into hard and fresh rocks is well known, but the evidence is clear and conclusive that the preglacial hills and mountains, and most of the valleys (including all the large ones), were rarely more than a little modified in shape and size. one of the principal effects of the ice age is the widespread distribution of glacial deposits, and other deposits which were formed under water in direct association with the ice. such materials have been described in the chapter on "glaciers and their work." as a direct result of the ice age, many thousands of lakes came into existence throughout the glaciated region where few, if any, previously existed. many of these lasted only while the ice was present because their waters were held up by walls of ice acting as dams. thousands of others still persist, most of these having their water levels maintained by dams of glacial débris left by the ice across valleys. good examples of lakes of both types, including a summary of the remarkable history of the great lakes, are considered in the chapter on "a study of lakes." many drainage changes, gorges, and waterfalls have also directly resulted from the great ice age. in fact it is not too much to say that practically all true gorges and waterfalls of the glaciated region have originated as a direct result of the ice age. the most remarkable combination of waterfall and gorge thus produced is that of the world-famous niagara, described in the chapter on "stream work." not only are niagara falls and gorge of postglacial origin but there was no niagara river as such before the ice age. in new york the well-known ausable chasm, trenton falls gorge, and watkins glen are all excellent examples of gorges cut since the ice age by streams which, because their old valleys were filled with glacial débris, have been forced to take new courses. a gorge of very special interest is that at little falls in central new york. this gorge, two miles long, with its precipitous walls hundreds of feet high, is the most important gateway for traffic between the atlantic border and the great lakes region. the bottom of this defile contains six tracks of the new york central and west shore railroads, the barge canal, an important highway, and the mohawk river. before the ice age there was a stream divide instead of a gorge, several hundred feet above the present river level. during a late stage of the ice age, when the great lakes drained through the mohawk valley, a tremendous volume of water passed over the divide and cut it down to form nearly all of the gorge except the inner or bottom trench which has since been eroded by the mohawk river. [illustration: fig. .--sketch map of the region between lake george and schenectady, new york, showing how certain of the main drainage courses have been revolutionized by the great retreating ice sheet and the deposits it left. preglacial courses shown by dotted lines only where essentially different from the present streams. (by the author, as published by new york state museum.)] only a few of the numerous stream changes directly due to the ice age will be briefly referred to. certain of the principles involved are exceptionally well illustrated in the general vicinity of saratoga springs and lake george, new york. during the retreat of the great glacier a lobe of ice occupied the lake george valley and forced the hudson river west over a divide at stony creek. then, because of heavy glacial deposits near corinth, the hudson could not continue south through what had been the preglacial valley of luzerne river, but it was forced eastward over a divide in a low mountain ridge to glens falls. the remarkable shift of the sacandaga river from its preglacial channel was caused by the building up of a great morainic ridge across the valley in the vicinity of broadalbin. the drainage of the basin of the upper ohio river has also been revolutionized as a result of the glaciation. all the drainage of western pennsylvania passed northward into lake erie just before the ice age instead of southwestward through the ohio river as at present. rivers as large as the mississippi and the missouri were also more or less locally deflected from their preglacial courses. thus the missouri, which in preglacial time followed the james river valley of eastern south dakota, was forced, by a great lobe of retreating ice, to find its present course many miles farther west. how long ago did the ice age end? in seeking an answer to this question we should bear in mind not only the fact that the ice age ended at different times, according to latitude, the more southern districts having been first freed from ice, but also the fact that approximately , , square miles of the polar regions are now ice-covered, so that in a real sense those portions of the earth are still in an ice age. some of the best estimates of the length of postglacial time for a given place are based upon the rate of recession of niagara falls, the average of the estimates being about , years. the evidence for this conclusion is briefly set forth in chapter iii. a careful study of the rate of recession of st. anthony falls, minnesota, has led to the conclusion that the last retreat of the ice occurred there from , to , years ago. certain clays deposited under tidewater since the last withdrawal of ice in sweden show a remarkable succession of alternating layers thought to represent seasonal changes. by counting the layers it has been estimated that stockholm was freed from ice only , years ago. although the actual duration of the ice age is by no means accurately known, we can be quite sure that the time represented is far longer than that of postglacial time. that it must have lasted fully , years seems certain when due consideration is given to amount of time necessary to bring about the repeated changes of climate between the glacial and interglacial stages; the amount of plant accumulation during the interglacial stages; the amount of weathering and erosion of the various layers of glacial deposits. some estimates run as high as , , years for the duration of the ice age, and an average is about , , years, which probably indicates, at least roughly, the order of magnitude of the time involved. when it is considered not only that the fact of the great ice age was not even thought of until , but also that many factors enter into the general problem of the climate of geologic time, it is not surprising that the cause (or causes) of the glacial climate is still not definitely known. a few of the various hypotheses which have been advocated to account for the glacial climate will now be very briefly referred to. one is that the increased cold (not more than to degrees for the yearly average) was brought about by the notably increased altitudes of late tertiary and early quaternary times in northern north america and europe. in this connection it is interesting to note that the four times of real glaciation during geologic time (mid-proterozoic, early paleozoic, late paleozoic, and early cenozoic) did occur directly after great crustal disturbances and notable uplifts of land. according to this hypothesis the interglacial stages would have to be explained by a rather unreasonable assumption of repeated rising and sinking of the glaciated lands. another hypothesis, long held in favor, is based upon certain astronomical considerations. thus we now have winter in the northern hemisphere when the earth is nearest the sun, but in about , years, due to wobbling of the earth on its axis, our winter will occur when the earth is farthest from the sun, thus making the winters longer and colder, and the summers shorter and hotter. after a much longer period of time the earth will be millions of miles farther from the sun in winter than in summer and this would still further accentuate the length and coldness of the winters. the interglacial stages represent the , year periods when the earth in winter (northern hemisphere) is nearest the sun. a difficulty in the way of accepting this hypothesis is that it is inconceivable that each glacial and interglacial stage lasted only , years. another objection to the hypothesis as an explanation of ice ages is that it is directly opposed by the fact of widespread glaciation at low latitudes either side of the equator during the late paleozoic ice age. another hypothesis is based upon variations in quantity of carbonic acid gas and water vapor in the air. increase or decrease of these constituents causes increase or decrease of temperature because they have high capacities for absorbing heat. "the great elevation of the land at the close of the tertiary seems to afford conditions favorable both for the consumption of carbon dioxide in large quantities (by weathering of rocks) and for the reduction of the water content of the air. depletion of these heat-absorbing elements was equivalent to the thinning of the thermal blanket which they constitute. if it was thinned, the temperature was reduced.... by variations in the consumption of carbon dioxide, especially in its absorption and escape from the ocean, the hypothesis attempts to explain the periodicity of glaciation (i.e., glacial and interglacial stages)." (chamberlin and salisbury.) still another suggested explanation is based upon variability of amount of heat radiated by the sun. slight variations are now known to take place, and possibly in the past during certain periods of time these variations may have been sufficiently great to cause a glacial climate with interglacial stages. here, as in the case of so many other great natural phenomena, a single, simple explanation does not seem sufficient to account for all the features of the several well-known glacial epochs of geologic time. two or more hypotheses, or parts of hypotheses, must more than likely be combined to explain a particular ice age. chapter xvii evolution of plants have we any knowledge regarding the beginning of life on our planet? our answer to this question must be decidedly in the negative. we can, however, be very positive in regard to two important matters concerning life in early geological time, namely, that plants must have existed before animals, and that the very oldest known (archeozoic) rocks of the earth contain vestiges of organisms. we may be sure that plants preceded animals because animal life ultimately depends upon plants for its food supply or, in other words, all animals could never have been carnivorous. now, if we can prove that organisms existed during archeozoic time, it is evident that plants at least must have lived in that oldest known era of earth history. that living things did then exist is proved by the common occurrence of graphite, a crystallized form of carbon, in the oldest known of the archeozoic rocks. the facts that flakes of graphite are abundantly scattered through many layers of strata of archeozoic age, and that adjacent layers of strata contain such varying amounts of graphite, render it practically certain that such graphite represents the carbon of organisms. graphite existing under such conditions could not be of igneous origin. carbonaceous or bituminous strata, so called because they contain more or less decomposed organic matter, would, when crystallized under conditions of metamorphism, yield graphite-bearing rocks exactly like those of archeozoic age, and there is every reason to believe that this was their origin. but, since only graphite (carbon) of the archeozoic organisms remains, the rest having disappeared through chemical change or decomposition, it is impossible to say whether much or all of it represents original plants or animals. in any case we can be very sure about the existence of plants (probably very simple or primitive types) in archeozoic time, but the presence of any form of animal life has not been proved. in the next, or proterozoic era, some plants and animals of definite types are known to have existed and, from here on in the present chapter, it is our purpose to consider the salient points in the geological history of plants, taking up the main types in the regular order of their appearance from the remote proterozoic days to the present. the very oldest known definitely determinable fossils of any kind are the more or less rounded masses of crudely concentric layers of carbonate of lime from one to fifteen inches in diameter found in middle proterozoic limestone of western ontario, canada. similar forms are abundant in late proterozoic strata of montana. they occur in large numbers as layers or reefs, in many cases repeating themselves through hundreds or even thousands of feet of strata. careful studies have shown that these forms are the limey secretions of some of the very simplest types of plants, that is thallophytes (e.g., seaweeds), which lived in water. before proceeding to describe the plants of paleozoic and later time, the reader should be impressed with the important fact that plants of higher and higher types came into existence throughout geological time in almost exactly the botanical order of their classification, that is to say, from the very simplest types (thallophytes) of proterozoic time there were gradually evolved, through the long geological ages, higher and higher plant forms reaching a climax in the complex and highly organized plants of the present time. this is the most significant general fact in regard to the geological history of plants. for the convenience of the reader the largest subdivisions in the classification of plants are here given. outline classification of plants i. cryptogams { . thallophytes (e.g., seaweeds, mushrooms) (seedless and { . bryophytes (e.g., mosses) flowerless) { . pteridophytes (e.g., "club mosses," "horsetails," ferns) ii. pteridosperms { (seed-bearing, { (e.g., seed ferns--wholly extinct) flowerless) { iii. phanerogams { . gymnosperms (e.g., cycads, conifers) (seed-bearing, { . angiosperms (e.g., grasses, lilies, flowering) { oaks, roses) throughout the first two periods--cambrian and ordovician--of the paleozoic era, plant life appears to have made little or no progress toward higher forms. the very simple thallophytes (e.g., seaweeds) continued to secrete concentric layers of carbonate of lime in almost exactly the same way as during the middle and late proterozoic era. remarkable reefs of such forms occur in the late cambrian limestone near saratoga springs, new york, where one locality has been set aside as a state park. during the ordovician there were seaweeds of the more familiar branching types without carbonate of lime supports, and these have left very perfect impressions in some of the ordovician strata. during the silurian period seaweeds continued, as, in fact, they did throughout succeeding geologic time to the present. the silurian strata seem to contain some vestiges of the first-known land plants, though the records are meager and some of the specimens are of a doubtful character. most interesting of all is a fern or fernlike plant found in france. when we consider the profusion of land plants (all of relatively simple types) of the next or devonian period, it seems certain that their progenitors must have existed in the silurian, and their remains may very likely be discovered. beginning with the devonian period of the paleozoic era the records show that important advances had taken place in the evolution of the plant kingdom. among the very simple thallophyte plants some seaweeds of unusually large size occur in fossil form, but the important fact is that all the principal subdivisions of the typical higher non-flowering plants (pteridophytes) as well as pteridosperms, and even some primitive representatives of the lower order flowering plants (gymnosperms) were well represented in the devonian. our knowledge of land plants earlier than the devonian amounts to almost nothing and they certainly could not have been at all prominent, but the fossil records make it very clear that many devonian land areas were clad with rich and diversified plant life. there were even forests, probably the first on earth, but they were far different, both in general and in particular, from those of to-day because the trees were all of exceptionally low organization types. during the next two periods--mississippian and pennsylvanian--there was no really important progress in the evolution of plants, and since these remarkable types of land plants have left such wonderfully preserved records in strata of the pennsylvanian or great coal age, we shall proceed to descriptions of the main types of that time, especially those which contributed to the formation of beds of coal. as shown by the abundant records, the land plant life of pennsylvanian time must have been not only prolific but exceedingly varied. thousands of species have been unearthed from the coal-bearing formations alone, and these must represent only a fraction of all species of plants which lived during the period. most prominent of all were the giant lycopods constituting the lowest main subdivision of the pteridophytes (see above classification). these great, non-flowering plants were at once the biggest, most common and conspicuous trees of the extensive swamp forests, and they were the greatest contributors to the formation of coal (plate ). many species have been described. they commonly attained heights of to feet and diameters of to feet. in one important type the fairly numerous branches bristled with stiff, needle-shaped leaves. when the leaves dropped off the older or trunk portions, scars were left spirally arranged around the trunks of the trees. in another important type the leaf scars were vertically arranged on the lower portions of the tree trunks. the upper portions of the trunks (rarely branched) were thickly set with long, slender leaves, which in some species were two or three feet long. an interesting fact is that the inner parts of the trunks of the great lycopods were filled with soft, pithy material. this explains why the fossil trees are nearly always flattened out, as a result of burial within the earth. the nonbranching type of lycopod has been totally extinct for millions of years, while the branching type is to-day represented only by small, mostly delicate, trailing plants familiarly known as "club mosses" and "ground pines." the most conspicuous trees of the great pennsylvanian lowlands and swamps have, indeed, left meager modern representatives, and here we have an excellent illustration of a once prominent group of plants which has dwindled away almost to extinction. another common type of pennsylvanian vegetation was the so-called "horsetail" plant or giant rush. the much smaller scouring rush, represented by several species to-day, is the direct descendant of this type which, during later paleozoic time, grew to be to feet high and to feet in diameter. the long, slender trunks filled with pith were segmented with variously shaped leaves arranged in whorls around the joints. a fine, vertical-fluted structure without leaf scars characterized the surfaces of the trunk. recent study has shown that many of the pennsylvanian plants, long classed as true ferns, were really "seed ferns," as described below. many of the true ferns grew to be real trees up to fifty or sixty feet high, but all paleozoic types were primitive in structure as compared with modern ferns. very remarkable among the later paleozoic plants were the pteridosperms, represented by the so-called "seed ferns." these now wholly extinct plants seem to have formed the connecting link between the seedless, flowerless plants (cryptogams) and the seed-bearing, flowering plants (phanerogams), because they bore seeds but not flowers. many of them were small and herbaceous, but others were tall trees, in general appearance resembling the tree ferns. "seed ferns," which play such an important part in the evolution of plants, are not known to have existed after paleozoic time. during the latter half of the paleozoic era some very primitive types of flowering plants (gymnosperms) existed. most abundant of these were the so-called cordaites, which were the tallest trees of the time, some having reached heights of over feet. the upper portions only bore numerous branches supplied with many simple, parallel-veined, strap-shaped leaves up to six feet long and six inches wide. excepting the pithy cores the trunks of these trees were of real wood covered with thick bark. trees of this kind became extinct in the early mesozoic era. very late in the paleozoic (permian period) two other types of the simple flowering plants (gymnosperms) made their appearance. these were the cycads and conifers, which were the most conspicuous trees during the first two periods of the mesozoic era. the cycads reached their culmination in the jurassic period, but they still exist in modified form in some parts of the world. the short, stout trunk was crowned with long, stiff, palm-like leaves. in fact, the cycads are distantly related to the palms, which belong to a higher group of plants. some specimens of cycads, especially from the mesozoic strata of south dakota, are so wonderfully fossilized that even the detailed structures of trunks, leaves, flowers, and seeds are so perfectly preserved that almost as much is known about these plants of millions of years ago as though they were living forms. the conifers, with which are classed present-day pines, spruces, and many other evergreen trees, gradually took on a more modern aspect, so that late in the mesozoic era they were much like those now living. among the most interesting trees were the sequoias, to which the living "big trees" and red-woods of california belong. these began in relatively late mesozoic time, reached their climax in numbers, variety of species, and widespread distribution in the early cenozoic era; and are now almost extinct, being represented by only two species in local portions of california. cordaites, trees which were so large and abundant in later paleozoic time, were reduced to extinction in the early mesozoic era. during mesozoic time the thallophytes, represented by seaweeds, were common. among the pteridophytes the ferns and "horsetail" plants were fairly common, but the very large forms gradually gave way to much smaller ones during mesozoic time. the giant lycopods of later paleozoic time dwindled almost to extinction even in early mesozoic time, so that from that time to the present they have been very small and relatively insignificant. tens of millions of years of earth history had passed before the true flowering plants--the angiosperms--appeared upon the earth. the cretaceous period marks their advent. so far as known, these plants originated along the eastern side of north america, and very soon after their establishment they spread over the earth with amazing rapidity and dominated the vegetation as they do to-day, more than half of the existing species of plants being angiosperms. among the common types which have been unearthed from cretaceous strata are palms, grasses, maples, oaks, elms, figs, magnolias, willows, beeches, chestnuts, and poplars. [illustration: plate .--a slab of very early paleozoic (cambrian) rock, covered with some of the oldest known definitely determinable animal remains. these creatures lived in a sea which overspread the site of the rocky mountains of southern canada fully , , years ago. most of the fossils are trilobites (including some very small ones) and other related crustacean forms (lighter portions). (_after c. d. wolcott, smithsonian institution, washington, d. c._)] [illustration: plate .--(_a_) photographs of small slabs of ordovician strata full of fossils. these slabs are actual bits of sea bottom at least , , years old. the left picture shows "stone-lily" stems, so-called "sea mosses," brachiopods. right picture shows various species of brachiopods. (_photo by the author._)] [illustration: plate .--(_b_) an outcrop of middle ordovician stratified limestone in northern new york. this ledge is full of fossils similar to those above. the material was deposited on the floor of the ordovician sea which overspread much of the continent. (_photo by the author._)] the introduction of the higher flowering plants (angiosperms) "was, perhaps, the most important and far-reaching event in the whole history of vegetation, not only because they almost immediately became dominant, but also because of their influence upon the animal life of the succeeding periods. hardly had flowers appeared, before a great horde of insects, which fed upon their honey or pollen, seem to have sprung into existence. the nutritious grasses and the various nuts, seeds, and fruits afforded a better food for noncarnivores than ever before in the history of the world. it was to be expected, therefore, that some new type of animal life would be developed to take advantage of this superior food supply. as we shall see in the discussion of the tertiary (next chapter), the mammals, which kept a subordinate position throughout the mesozoic, rapidly took on bulk and variety and acquired possession of the earth as soon as they became adapted to this new food, quickly supplanting the great reptiles of the mesozoic." (cleland.) during the present or cenozoic era vegetation gradually took on a more and more modern aspect until the existing species were developed. the grasses especially developed and spread rapidly, but the cereals did not evolve until late in the era. certain single-celled plants, called diatoms, may be especially mentioned, for they must have literally swarmed in some of the tertiary seas which spread over parts of the present lands. "the microscopic plants which form siliceous shells, called diatoms, make extensive deposits in some places. one stratum near richmond, virginia, is thirty feet thick and is many miles in extent; another, near monterey, california, is fifty feet thick, and the material is as white and fine as chalk, which it resembles in appearance; another, near bilin, in bohemia, is fourteen feet thick.... ehrenberg has calculated that a cubic inch of the fine, earthy rock contains about forty-one thousand millions of organisms. such accumulations of diatoms are made both in fresh waters and salt, and in those of the ocean at all depths." (j. d. dana.) chapter xviii geological history of animals (excluding vertebrates) a study of the animals of the past is not only of great interest in itself, but also it furnishes a mainstay of the great doctrine of organic evolution. at the very outset of our discussion the reader should have already in mind at least the main subdivisions of the animal kingdom in order to reasonably well understand where the important animal types of the different geological ages fit in, and how those types bear upon the doctrine of evolution. the accompanying, very brief, general classification includes the usually recognized subkingdoms with special reference to representatives of those which are of most geological and evolutionary significance. reading downward in this classification, the degree of complexity of organization steadily increases from single-celled animals to man himself. i. protozoans, e.g. foraminifers (with lime carbonate shells) {sponges ii. coelenterates, e.g. {so-called "jellyfishes," graptolites {corals {so-called "sea lilies" iii. echinoderms, e.g. {so-called "starfishes" {so-called "sea urchins" iv. worms, v. molluscoids, e.g. {so-called "sea mosses" {brachiopods {clams, oysters { {snails {pearly nautilus, vi. mollusks, e.g. { { ammonites { {cephalopods, e.g. {so-called { { "cuttle fishes" {trilobites vii. arthropods, e.g. {crabs, lobsters {so-called "sea scorpions" {insects {ostracoderms {fishes viii. vertebrates, e.g. {amphibians {reptiles {birds {mammals (including man) before entering into a brief but rather systematic discussion of some of the most important types of animals which lived during geological time, it may be well for the reader to have in mind some of the most important conclusions which have been reached as a result of the study of the fossil animal records. these conclusions may be summarized as follows: . animal life existed many millions of years ago. . not only the animals of to-day, but also those of any given geological period, directly descended from those of preceding geological periods. . animal life has undergone continuous change since its introduction upon the earth, so that each group of strata, representing a particular geological age, contains a characteristic assemblage of fossil animals. . many of the changes in the history of animals have been progressive or evolutionary, so that strata of early geological time contain distinctly more primitive or lower order forms than the strata of late geological time. but, while the line of evolution has been maintained without a break, culminating in man, there have been many offshoots of a retrogressive nature. . even as far along in geological time as the early paleozoic era, the highest subkingdom--vertebrates--had no representative whatever. in other words, all the important subdivisions of animal life from a little below fishes to man have been evolved since about the close of the ordovician period. . any species of animal which ever became extinct has never been known to reappear, and literally tens of thousands of species are known to have become extinct. . no species like those now living are found in the more ancient strata, such being confined to the strata of relatively recent geological dates. . while more and more highly organized animals have continuously been evolved, many of the earlier and simpler types have persisted, a remarkable case in point being the single-celled animals called foraminifers which may be traced, without very notable change, through the tens of millions of years of geological time from the late proterozoic era to the present day. . many species have been able to maintain themselves practically without change through long stretches of geological time, while others have had only very brief existence. when did animal life begin on the earth, and what were the first forms like? we can only partially answer the first question by saying that animals have existed for tens of millions of years, certainly as early at least as proterozoic time. up to the present time we are utterly in the dark as to what the earliest animal forms looked like, but we have positive knowledge that the oldest forms found as fossils in the rocks represent creatures which were far more primitive and lower in organization than many animals of to-day, and that since those oldest known forms lived, the animal kingdom has undergone various profound alterations. in view of the above statements, and also the fact that the oldest known plant forms were extremely simple or single-celled, it is more than likely that the first animal life of the earth was single-celled. in harmony with this view is the fact that fossil single-celled animals are found in the very oldest (proterozoic) rocks which contain any definitely determinable fossil animals. do the most ancient known rocks show that animal life existed during archeozoic time? in the preceding chapter we pointed out the fact that the carbon (in the form of graphite), so commonly present in those most ancient known strata, proves the existence of life of some kind during archeozoic time. but because nothing like definitely determinable fossil forms have thus far been discovered in those rocks, we cannot be sure whether the carbon represents plant or animal life or both, though certainly plants of very low order at least must have existed. because of the intense alteration (metamorphism) of those very old strata, all definite forms have long since been obliterated as such. we may, however, in the light of the vast evolution which took place through succeeding geological time, be very sure that any animals which may have existed during archeozoic time were in general much simpler forms than those of even early paleozoic time. the early and middle proterozoic strata throw no more light upon the early history of animal life than do the archeozoic strata. the upper or later proterozoic rocks, however, contain the oldest recognizable animal fossils. very recently fossil remains of single-celled, shell-bearing protozoans have been found in northern france, while the upper proterozoic strata of the rocky mountains in montana, and the grand canyon of arizona have yielded worm tracks, a molluscoid (brachiopod) and fragments of lower forms of arthropods. this record, although very meager, clearly proves that animal life was so well advanced by late proterozoic time, that next to the highest subkingdom was actually represented (see above classification), and that there must have been a long line of simpler and simpler ancestors, probably extending far back into the archeozoic era. when we stop to consider that archeozoic and proterozoic time was fully as long as all succeeding geological time, it is not so surprising that fairly highly developed animals (except vertebrates) had been evolved before the close of the proterozoic era. in regard to abundance of fossil animals the oldest (cambrian) paleozoic strata stand out in marked contrast to the proterozoic. many hundreds of species of animal fossils have been described from cambrian strata, and a great many others yet remain to be discovered. cambrian fossils are remarkably numerous, varied in species, and complex in organization (plate ). all subkingdoms of animals except the vertebrates were represented, though usually only by the simpler types in each subkingdom. it is quite generally agreed that no less than per cent of animal evolution had taken place before the beginning of the cambrian period. the reader should, however, clearly bear in mind that tremendous advances in evolution have taken place since early cambrian time when not only all forms from lower scale arthropods to the highest mammals (including man) have evolved, but also when many thousands of species of lower subkingdom animals developed. why are the very early paleozoic strata so rich in fossils, while the immediately preceding proterozoic rocks show so few? the seemingly sudden appearance of so many highly developed animals in earliest paleozoic (cambrian) time is one of the most important considerations in the history of animal life, and it is by no means definitely understood. the following statements bear directly upon the problem: the early animal forms were probably soft or gelatinous without shells and lived mostly in the open sea where food (seaweeds, etc.) was abundant. such animals were very unfavorable for preservation in fossil form. then, late in proterozoic time or very early in the paleozoic, a severe struggle for existence set in, probably due to crowding along shores, and hard parts began to develop both for support and defensive purposes. such hard parts or shells were commonly favorable for fossilization. this view is strongly supported by the fact that very thin shells only are known from late proterozoic rocks, and mostly very thin shells from the earliest cambrian, the heavier shells having been evolved later. a fact of importance to bear in mind in this connection is that just at the critical time (late proterozoic) in shell development, the lands of the earth were undergoing widespread and deep erosion as pointed out early in the chapter on "ancient earth history." the earliest cambrian strata, therefore, nearly everywhere rest upon the deeply eroded surface of the proterozoic rocks so that the transition strata--the very ones which would contain most fossils of the early shell development stage--are nearly everywhere missing. finally, mention should be made of the fact, that all archeozoic strata are profoundly altered (metamorphosed), and so are nearly all proterozoic strata, except the later. fossils once present in those rocks would of course have been obliterated by the process of metamorphism, but the fact remains that very considerable thicknesses of practically unaltered proterozoic strata show few if any animal fossils. we shall now proceed to a rather systematic consideration of the most interesting and significant types of creatures which have inhabited the earth since the beginning of paleozoic time at least twenty-five million years ago. it is our purpose to bring out the salient features in the history of each subkingdom of animals, beginning with the lowest or simplest, and taking up in turn the higher and higher subkingdoms. by this method the reader may easily follow the main thread of organic evolution or progressive change which runs through most of the known history of animal life of our planet, and which is so important in the science of geology. protozoans, which include all the tiny single-celled animals, are known in fossil form even in late proterozoic rocks and, as proved by the fossil records, they have been more or less abundant ever since, even now swarming in large portions of the surface sea waters. one of the most remarkable facts in the history of animal life is, that such exceedingly simple creatures persisted almost without change through the tens of millions of years when such profound and even revolutionary changes took place in the animal kingdom in general. the only fossil protozoans are those which developed delicate shells either of carbonate of lime (the foraminifers) or silica. special mention should be made of the cretaceous period when foraminifers must have been exceedingly profuse in clear sea waters which spread over the gulf coastal plain of the united states, parts of southern england, much of france, and other areas, as proved by their accumulated shells which make up formations of chalk hundreds of feet in thickness and many miles in extent. [illustration: fig. .--a compound colony of fossil graptolites characteristic of late ordovician time, fully , , years ago. each little prong once held a tiny individual living graptolite which was a very simple type of animal belonging to the subkingdom called "coelenterates." (modified after ruedemann.)] the coelenterates, which comprise the simplest of the many-celled animals, are saclike forms with mouth openings, but with few other differentiations of parts. all are marine animals. of these the sponges are porous, and the other types (including corals) have tentacles around their mouths. sponges have been more or less common from early paleozoic time to the present, and they have undergone relatively little change. "jellyfishes," which are in truth not fishes at all, are wholly soft or gelatinous coelenterates which have left some very remarkable impressions and casts in strata of very early paleozoic age, those very ancient forms evidently having been almost exactly like those of to-day. graptolites were slender, plumelike, delicate forms consisting of colonies of tiny individuals, in many cases in branching or radiating combinations. they existed only during the first half of the paleozoic era. both because they floated in the open sea, thus permitting widespread distribution, and because they underwent many distinct species changes during short geologic intervals, they are among the most useful fossils for separating the various subdivisions of strata of the earlier paleozoic. [illustration: fig. .--corals, representing the very simple subkingdom of animals called "coelenterates": a, fossil shell of an individual "cup coral" found only in paleozoic strata; b, a compound or "chain coral" skeleton found only in relatively old paleozoic strata; and c, part of a modern coral colony showing living corals.] corals comprise another important branch of the coelenterates. during the cambrian period there were corallike sponges and possibly simple corals, but from the early ordovician to the present true corals have been common, especially in the clearer, warmer seas. their carbonate of lime skeletons have accumulated to help build up great limestone formations representing almost every geologic age from early paleozoic time to the present. paleozoic corals were in general notably different from those of later time. there were three main types including the compound "honeycomb" and "chain" types, and the solitary or compound "cup" type. they all had four, or multiples of four, radiating partitions; were rarely branched; and were generally large, some individual cup corals ranging in length from half an inch to a foot or more. modern corals (beginning with the mesozoic) have six or eight partitions; are nearly all profusely branched; and are mostly tiny individuals. echinoderms are all marine animals, including the so-called "starfishes," which are not really fishes. they have body cavity, with digestive canal, low order nervous system, and a water circulatory system. most of them have radially segmented shells or skeletons. the oldest fossil forms are found in cambrian strata, these being very simple or primitive types, with a bladderlike head set on the end of a segmented stem, both head and stem having been supported by carbonate of lime. such forms lived only to middle paleozoic time. ordovician strata contain representatives of all the main types of echinoderms in well-fossilized forms. [illustration: fig. .--fossil echinoderms or so-called "starfishes": a, simple type known as the "stone lily" with head, stem, and roots intact from silurian strata; b and c, irregular and regular higher type echinoderms called "sea urchins" from cretaceous strata.] a stemmed echinoderm of special interest, first known from the ordovician, has persisted to the present day. it is the so-called "sea lily" or "stone lily," consisting of a complex, headlike portion attached to the sea bottom by a long segmented stem, the whole being supported by lime carbonate. they were very numerous during the silurian, but they seem to have culminated in variety of species and numbers of individuals during the mississippian period when they were exceedingly profuse. hundreds of species of "stone lilies" are known from mississippian strata alone, and in certain localities, as at crawfordsville, ind., and burlington, ia., the "stone lily" remains are so numerous that when living they must have literally forested parts of the sea bottom. from mississippian time to middle mesozoic time they occupied a relatively subordinate position when they again developed in great profusion. the mesozoic forms were distinctly more like those of to-day, and it scarcely seems credible that any creature could have contained such a multiplicity of hard parts, more than , segments having been counted in a single fossil from jurassic strata. the "sea lilies" of to-day are relatively unimportant. the familiar five-pointed "starfishes," so common along our seacoasts, are first known from the ordovician, and they persisted through the many millions of years to the present time with remarkably little change. the so-called "sea urchins" live in rounded, segmented lime-carbonate shells bristling with movable spines. "sea urchins" are first known from the ordovician, but they did not become abundant and diversified until mesozoic time, when many of them took on a very modern aspect. worms are known to have existed ever since late proterozoic time, as proved by the occurrence of tracks, borings and more rarely delicate impressions on rock surfaces. because of their softness they have rarely been well fossilized and are, therefore, of no great evolutionary or geological importance. [illustration: fig. .--fossil brachiopods belonging to the subkingdom of animals known as "molluscoids": a, b, c, forms characteristic of the ordovician, devonian, and triassic periods, respectively.] the subkingdom molluscoids has been richly represented by both the so-called "sea mosses" and brachiopods. the "sea mosses" form colonies of tiny mosslike tufts, resembling corals outwardly, though they are much more highly organized. they have been common from ordovician time to the present, their carbonate of lime skeletons often having contributed to the building of limestone formations. brachiopods always have two external shells or valves, in most cases working on a hinge, and also a pair of long, spiral-fringed arms associated with the soft part of the animal inside the shells. they differ from the other type of bivalve (e.g., clam, oyster) in that they are symmetrical with reference to a plane passed through the middle of the shells at right angles to the hinge line. they have rarely grown to be more than a few inches long. a few scant brachiopod remains are known from the late proterozoic, but throughout known geologic time they reached their greatest development in the paleozoic era, more especially in the devonian period. combining number of species and number of individuals, the brachiopods probably hold the record of all important groups of fossil animals, more than , species being known. many layers of rock are filled with their shells (plate ). since the close of the paleozoic they have fallen off notably, and are now represented by relatively few small forms. from the standpoint of evolution it is interesting to note that in very early paleozoic time the brachiopods were mostly small, of relatively simple organization, and their thin shells were not joined by hinges. later they became larger and more complex and their thicker shells worked on hinges. nearly all the paleozoic forms had long, straight hinge lines, which made it difficult for their enemies to open them. along with the change to narrower, curved hinge lines came the decline of the tribe. they have been of great value to the geologist in subdividing the geological column of strata into its many formations. the mollusks, which are more highly organized than the molluscoids, have more or less distinctly developed heads and locomotive organs. many thousands of species are now extinct, the classes of most geological importance being represented by clams, snails, and the pearly nautilus. most of them have shells and gills for breathing. the members of the simplest group, well represented by the clam tribe, possess two similar shells working on hinges, so that in this regard they are much like brachiopods, but, unlike the latter, they are not symmetrical with reference to a plane at right angles to the hinge line. cambrian strata contain the oldest known of the fossil forms where they are small, relatively thin-shelled, and rare. in marked contrast to the brachiopods these bivalves have rather steadily increased in numbers of species and individuals to the present time, now being represented by thousands of forms. during the mesozoic era they greatly out-numbered the brachiopod bivalves and took on a more distinctly modern aspect, when the oyster tribe and closely related types were prominently developed. culmination in size and thickness of shell seem to have been reached in early cenozoic time, strata of that age in certain places, for example in georgia and southern california, being filled with oyster shells to inches long and to inches thick! in addition to their gigantic size and thickness, many of the shells were fluted or ribbed, and so they represented an extreme type of defensive armor among the lower animals. snails have existed from the earliest paleozoic era to the present time, and the outstanding fact of interest concerning them is that they furnish one of the finest illustrations of an important class of animals which has undergone practically no conspicuous change or evolution during all those millions of years of time. [illustration: fig. .--sketches of chambered cephalopods showing the main steps in the evolution of the shell forms and compartment partitions: a, b, the only kinds in cambrian time; c, d, forms added in the ordovician; e, added in the devonian; f, added in the late paleozoic; g, h, characteristic of the mesozoic era; and i, a living form (pearly nautilus) cut through. (drawn by the author.)] we shall now turn our attention to the highest order of mollusks--the cephalopods. these creatures, whose heads are armed with powerful tentacles and supplied with complex eyes, propel themselves by forcible ejection of water. one general type--the chambered cephalopod--has a shell divided into compartments (e.g., modern pearly nautilus) which are successively built up and abandoned by the animal as it grows larger. these chamber-shelled cephalopods constitute one of the most remarkable and instructive illustrations of evolutionary change within any important subgroup of invertebrate animals, ranging from early paleozoic to the present. both because of the abundance of fossil forms in rocks of all these periods of geological times, and because certain of the evolutionary changes are so clearly expressed in the well preserved shell portions, they are specially adapted for study. in the late cambrian only straight and slightly curved forms with smooth, nearly straight chamber partitions existed. notable advance took place during the next (ordovician) period when there were straight, curved, open-coiled, and even close-coiled forms. all had simple partitions, and the straighter forms predominated. "the size attained by the ordovician cephalopods was probably never surpassed by representatives of the class. some of the (straight) shells were twelve to fifteen feet in length, and a foot in diameter. from this great size they ranged down to or below the size of a pipe stem." (chamberlin and salisbury.) they were more than likely the undisputed masters of the ordovician seas. silurian time marked no important change in their structures, but the coiled forms predominated for the first time. during the second half of the paleozoic era all preceding types with simple partitions persisted, but in some forms the simple partitions gradually became angled and finally rather complexly curved. during the mesozoic era the partition lines of the close-coiled forms evolved until a most remarkable degree of complexity was attained, comparable, indeed, to the sutures of the human skull plates. these remarkable forms called ammonites, of which more than , species are known, began with the mesozoic, reached their climax, and passed out of existence toward the close of the same era. certain strata of jurassic age are literally filled with ammonites, some shells being several feet in diameter. various eccentric changes took place in the ammonites shortly before their extinction. some shells became uncoiled and even straight, thus outwardly at least showing reversion to the original early paleozoic ancestors, but with retention of the complex partitions. others assumed spiral shapes and still others became curved or coiled at each end. while these extraordinary evolutionary changes were going on among the chambers of cephalopods during mesozoic time, some of the ancient close-coiled forms with very simple partitions managed to persist. in fact this simple type, almost exactly like its early paleozoic ancestor, has been the only one out of this whole remarkable class of animals to persist to the present time, being now barely represented by the well-known pearly nautilus of the indian ocean. during the mesozoic era the highest type of cephalopod, represented by modern squids and so-called "cuttlefishes," branched off and developed in great profusion. these had slender internal shells, but no external chambered shells. an inky black liquid secreted in a bag was forced out to cloud the water when the animal was escaping its enemy, thus antedating by millions of years the principle of smoke screen so effectively used by ships during the world war. some jurassic species got to be over two feet long, and a few specimens of that age have been found in such perfect state of preservation that drawings of the fossils have actually been made with the ink (after moistening) taken from their own ink bags. [illustration: fig. .--a fossil nonchambered cephalopod of jurassic age. it was closely related to the modern squid, and its ink bag is well shown just to the left of the middle. (modified after mantell.)] before concluding this chapter we shall take up the salient points in the geological history of arthropods which constitute the highest subkingdom of all animals except the vertebrates. they are now very abundant and varied, familiar examples being crabs and insects. a few scant remains of simpler forms are known from the proterozoic, but since very early paleozoic time they have been very common and have undergone great evolutionary changes. a few striking examples only will be dwelt upon. among the most common and interesting of all paleozoic animals were the trilobites, distantly related to modern lobsters and crabs. [illustration: fig. .--restorations of trilobites based upon actual fossils characteristic of earlier paleozoic time: a, cambrian; b, ordovician; c, devonian; b shows the appendages.] some of these grew to be two feet long, but usually they were only one or two inches long. first known from the earliest paleozoic, they reached their culmination relatively early in the era and then dwindled away to utter extinction before its close. "they were characteristic of the paleozoic era, beginning in great variety in the lower cambrian and dominating the seas of the cambrian ( species) and ordovician ( species). in the silurian, though they were still common, the trilobites were nevertheless on the decline ( species), and this ebbing of their vital force is seemingly shown in many picturesque forms replete with protuberances, spines, and exaggeration of parts. as a rule, in evolution, one finds that when an organic stock is losing its vital force there arises in it an exaggeration of parts, as if heroic efforts were being made to maintain the race. spinosity in animals is often the prophecy of tribal death. in the devonian, the variety and number of the trilobites were greatly reduced ( species), at a time when the ancient types of fishes, which undoubtedly fed on these crustaceans (trilobites), began to be common in the seas. in the later paleozoic seas, the trilobites were relics, or animals surviving from a time better suited to their needs, and one by one they vanished, until a little before the close of the paleozoic era none were left." (schuchert.) [illustration: fig. .--a giant, sea scorpion of devonian time. length nearly feet. (after clarke and ruedemann, new york state museum.)] an extraordinary type of arthropod which ranged throughout paleozoic time and became extinct at its close was the so-called "sea scorpion," closely related to the modern scorpion. their five or six pairs of appendages all came out from the head portion, one pair in some cases having been developed as powerful pincers. their culmination in size was reached during the devonian when some forms grew to the astonishing length of over eight feet! such gigantic creatures must have been tyrants of the seas until they were subdued by the oncoming powerful fishes. true scorpions are known from rocks as old as the silurian. lobsters and crabs made their appearance during the mesozoic era. since insects constitute the highest subdivision of arthropods, they include the very highest forms of animal life except the vertebrates. the oldest known fossil insects are from pennsylvanian strata, more than , species having been described from rocks of that age. they were all simple or primitive types like cockroaches and dragon flies, and were remarkable for size. giant cockroaches got to be four inches long. one form of dragon fly, with a spread of wing of over two feet, was probably the largest insect which ever lived (plate ). development of insect life was especially favored during the great coal age because of the prolific vegetation, but more than likely insects originated somewhat earlier. early in the mesozoic era a great progressive change began to come over insect life and higher forms gradually evolved until by the close of the era many of the highest types like flies, ants, and bees were common. as might be expected, the highest insects did not develop until after the appearance of the true flowering plants in later mesozoic time, butterflies apparently not having evolved until early in cenozoic time. many of the thousands of known species of fossil insects are from strata of tertiary age during which time they may have been even more numerous than to-day, although there are about , species now living. an almost incredible case is a tertiary stratum only a few feet thick in switzerland from which nearly , species of insects have been unearthed. another famous locality is florissant, colorado, where during early tertiary time there was a small lake into which showers of fine volcanic dust fell and entombed vast numbers of insects, more than , species having been unearthed. still another extraordinary occurrence is along the shores of the southern baltic sea where more than , species of insects have been found in a fossil resin called amber. the insects were caught in the still soft sticky resin while it was exuding from the trees, and thus we have the insects, fully two or three million years old, literally embalmed and marvelously preserved, often in beautifully transparent amber. chapter xix geological history of vertebrate animals (including man) vertebrates comprise the highest subkingdom of all animals with man himself at the very top. they are characterized by the possession of a vertebral column, which, in all but the very simple or primitive forms, is an ossified backbone. their main subdivisions are given in the classification table near the beginning of the preceding chapter. the oldest known vertebrates, found in fossil form in middle ordovician strata, were represented by curious and bizarre creatures called ostracoderms, or more popularly "armor fishes." they were not true fishes because they were really somewhat lower in the scale of organization than fishes. some were distinctly fishlike in appearance, and others notably resembled certain of the arthropods, so that some students consider them to have formed the connecting link between the highest invertebrates (arthropods) and low order fishes of the vertebrates. the vertebral column always consisted of cartilage or gristle and, in most forms, it extended through tail fin. none had true side fins like fishes, but many were provided with a pair of jointed flappers or paddles. the jawlike portions of the heads moved over each other sidewise as, for example, in beetles and not up and down in true vertebrate fashion. two eyes were always very close together. one of the most striking features was the protection of the head and fore part of the body by an armor of bony plates, while the rest of the body had scales. they seldom grew to be more than six or seven inches long. beginning in the devonian, they remained rare during the silurian, and then in the devonian period they reached their climax of development only to become extinct at its close. many species were abundantly represented in many parts of the world. by some the ostracoderms are thought to have been a primitive (sharklike) fish development in the wrong direction, and hence they became extinct. [illustration: fig. .--two restored forms of very primitive and ancient (devonian) types of vertebrates called "ostracoderms." they were lower in organization than true fishes. (after dean-woodward and british museum, respectively.)] fishes, represented only by very primitive sharks, are known to have existed as early as the silurian period, but the remains are scant. during the devonian period, however, they showed a marvelous development into many species and countless myriads of individuals. the devonian is, therefore, commonly called the "age of fishes." these very ancient (devonian) primitive (fish) types of vertebrate animal life are of profound significance in organic evolution because they were the direct progenitors of the great groups of still higher vertebrates which since later paleozoic time gradually increased in diversity and complexity of structure through amphibians, reptiles, birds, and mammals finally to man himself. [illustration: fig. .--restorations of characteristic devonian fishes, based upon actual fossils: a, a "lung fish" with leglike fins (after huasakof); b, a "ganoid." (after nicholson.)] in marked contrast to the most typical and highly organized fishes so abundant to-day, all devonian fishes were of simple types with cartilaginous skeletons and vertebrated tails. many of them were also generalized types, that is, associated with their clearly defined fish characters were others connecting them with certain higher vertebrates, as, for example, amphibians and reptiles. thus all their tail fins were vertebrated as in reptiles; their labyrinthine, internal tooth structure was to be an amphibian feature when those creatures evolved; many had protective armor or bony scales like most early amphibians and many modern reptiles; and many had paired fins which were something like jointed legs. most abundant and highly organized of the devonian fishes were "ganoids," characterized by a covering of small plates or bony scales set together but not overlapping like in typical modern fishes. their intricate tooth structure and limblike fins strongly suggest the amphibians of later paleozoic time. the skeleton of cartilage gradually became somewhat ossified during succeeding geologic periods. from their great profusion and diversity in the devonian period the ganoids have steadily fallen away until they now have very few descendants like the gar pike. another important group of remarkable fishes, now totally extinct, but common in devonian and somewhat later time, had heavy, bony armor plates over the fore part of the body. those which grew to be fifteen to twenty-five feet long were probably the rulers of the middle paleozoic seas. another remarkable devonian fish was able to breathe in both water and air because, like their few modern descendants, they had both gills and lungs. because of their leglike fins and lung sac, it is commonly believed that they were progenitors of the later paleozoic amphibians. the simplest of all fishes, the sharks, began in the silurian, underwent no important change through the millions of years since, and are now of course well represented. during early cenozoic time the sharks seem to have reached culmination in size--sixty to eighty feet long, with teeth five or six inches long. among modern fishes the most abundant by far, and the most highly organized, are the true bony fishes, called the "teleosts," which made their first appearance in the middle of the mesozoic era. those earliest forms clearly show their descent from the ganoids. apparently they have not yet passed their prime. we shall now consider the next higher group of vertebrates, the amphibians, which breathe by gills when young and later develop lungs. many live both on land and in water like the frogs. unlike fishes they have legs with toes and not fins. beginning probably in the devonian as a branch of the fishes, amphibians showed a marvelous development during later paleozoic and very early mesozoic times when they reached their climax, after which they fell off remarkably, being now relatively unimportant like the frogs and salamanders. they are of special significance because they were the first of all the back-boned animals (vertebrates) to inhabit the land which they dominated only until the great rise of reptiles of mesozoic time. the reptiles in fact evolved from the amphibians in the late paleozoic when many transition forms occurred. (plate .) during those ancient days the numerous and very diversified amphibians were like giant salamanders, commonly five to eight feet long, with one triassic form fifteen to twenty feet long, and with heavily armored skulls two to four feet long. turning now to the reptiles we find that they are much more distinctly land animals than the preceding types of vertebrates. reptilian life of the earth began in late paleozoic time as an evolutionary branch of the amphibians. the earliest forms were in many ways much like the amphibians, but gradually they diversified and progressed so that before the close of the mesozoic era, which has long been called the "age of reptiles," they were the rulers of the world. "they covered the land with gigantic herbivorous and carnivorous forms; they swarmed in the sea, and, as literal dragons, they dominated the air." (scott.) mesozoic reptiles are of special interest and significance not only in themselves, but also because from one of their branches the birds were evolved, and from another the mammals. "in advancing from the amphibian to the reptile the evolution of the vertebrates was far from finished. the cold-blooded, clumsy and sluggish, small-brained and unintelligent reptile is as far inferior to the higher mammals, whose day was still to come, as it is superior to the amphibian and the fish." (norton.) since the reptiles of the mesozoic era constitute one of the few most remarkable and diversified classes of animals which ever inhabited the earth, we shall attempt to give the reader a fair idea of the most typical groups which have been totally extinct since the close of the mesozoic era some millions of years ago. of the swimming reptiles which lived in the seas many types are known and only a few will be described. among these one important type was the ichthyosaur, a fishlike form which not uncommonly grew to be twenty to even forty feet long (plate ). the large head, sometimes four or five feet long, contained as many as big sharp teeth and enormous eyes up to a foot in diameter. the body was heavy set, and the neck very short. there were four short, stout swimming paddles, and the tail was vertebrated. some specimens of ichthyosaurs have been so perfectly preserved in mesozoic strata that even the unborn young are plainly seen in the bodies! in some cases it is actually possible to tell what was the last meal of a particular ichthyosaur those millions of years ago; in one specimen, for example, remains of creatures of the "cuttle-fish" tribe having been found in the exact position of the stomach. [illustration: fig. .--chart showing the main branches in the history of vertebrate (back-boned) animal life reaching its culmination in man. (by the author, in part after cleland.)] the mosasaurs of the late mesozoic were the only real sea serpents of the geologic ages. they were something like the ichthyosaurs, but with smaller heads and much longer, more slender, serpentlike bodies. some grew to be thirty or forty feet long. plesiosaurs were perhaps the strangest of all the mesozoic marine reptiles. they grew to be forty to fifty feet long, with stout body, very long, slender neck, small head, short tail, and four long, powerful swimming paddles which were distinctly leglike. these and the mosasaurs were both flesh eaters, as shown by the sharp teeth. [illustration: plate .--(_a_) restoration of a late paleozoic (coal age) landscape. showing the main kinds of plants which have entered into the making of most of our coal. giant "club mosses" both with and without branches, in the left background; giant "horsetail" (or "scouring rush") plants on the right; and seed ferns in the left foreground. a primitive reptile in the water; two large amphibians or giant salamanders, called "stegocephalians," on the land; and a great "dragon fly," two feet wide, in the air. (_from a drawing by prof. williston. courtesy of d. van nostrand co._)] [illustration: plate .--(_b_) photograph of a fossil fern or seed fern frond on a piece of shale millions of years old. the specimen is of the pennsylvanian age and was taken from the coal fields of pennsylvania. (_after white, u. s. geological survey._)] [illustration: plate .--restoration showing the general appearance of some of the largest animals which ever trod the earth. a mounted skeleton in the american museum of natural history is sixty-seven feet long, and the skeleton of a similar creature in the carnegie museum, pittsburgh, is eighty-seven feet long. they lived millions of years ago during the middle and late mesozoic era. (_after c. r. knight. courtesy of the american museum of natural history, new york._)] the most remarkable walking reptiles of all time were the dinosaurs or "terrible lizards." we shall describe enough types of these unique creatures to give the reader a fair idea of their appearance and habits. most astonishing of all were the sauropods including the largest animals which ever trod the earth. they grew to be as much as sixty to ninety feet or more in length. remarkably well preserved skeletons have been found, one from utah, eighty-seven feet long, being mounted in the carnegie museum of pittsburgh. the largest of these brutes stood fifteen to twenty feet high and they must have weighed thirty to fifty tons. the very long, serpentlike neck and tail, and very small head were grotesque features. considering the structure of the dinosaurs, the kind of strata in which they are embedded, and the associated fossil remains, it seems clear that they mostly lived in and near fresh water and on near-by lowlands. the character of their teeth shows that they fed entirely on soft plants which they must have habitually bolted because their teeth were not well adapted to grinding food. it is difficult to believe that a single huge beast could have consumed less than a few hundred pounds of vegetable matter per day, and, on account of the very small size of the head, he must have spent most of his time eating. also the comparatively very small size of the brain, and its simplicity of structure, render it certain that they were extremely stupid creatures. "to make up for this they had an enormous enlargement of the spinal cord in the sacral region (i.e., over the hind legs). this sacral brain--if we may so call it--was ten to twenty times bigger than the cranial brain. it was necessary in order to work the powerful hind legs and tail." (le conte.) [illustration: fig. .--skeleton of a great four-legged (sauropod) dinosaur. a mounted skeleton in the american museum of natural history, new york, is sixty-seven feet long. this creature lived millions of years ago during the jurassic period. (after marsh.)] another dinosaur, in some respects like the sauropod, was the stegosaur which grew to be twenty to thirty feet long, and heavier than the elephant. unlike the sauropod, it had a short neck and was armored with a double row of great plates over its back, and sharp spines (one to three feet long) toward the end of the tail. the excessive stupidity of the creature is proved by the fact that its very simple brain weighed less than three ounces! stegosaurs were plant eaters as indicated by the tooth structure, and, though they looked ferocious, they were probably not fighters, certainly at least nothing like the carnivorous types of dinosaurs we shall soon describe. [illustration: fig. .--skeleton of the curious kind of dinosaur (stegosaur) of mesozoic age with great bony plates over the back. length about thirty feet. (after marsh.)] the ferocious dinosaurs of mesozoic time were carnivorous, or flesh eaters, as shown by their numerous sharp teeth in relatively large heads. the largest known type is the tyrannosaur, an almost perfect skeleton of which, feet long and feet high, is mounted in the american museum of natural history in new york (plate ). so far as known, this was the largest carnivorous animal which ever walked on the earth. it is evident from the structure that it walked on its hind legs, the front ones having been much shorter and used something like arms. there were also various other smaller forms of two-legged flesh-eating dinosaurs, many of the wonderfully preserved tracks in the triassic sandstones of the connecticut river valley having been made by such creatures when they walked around over soft, sandy mud flats at least eight or ten million years ago. the sandy mud with its tracks became somewhat hardened and then deeply buried under much more sediment which, through the ages, has been eroded off, thus exposing to view certain of the layers covered with tracks. some bones of dinosaurs have also been found in the connecticut valley. [illustration: fig. .--skeleton (restored) of a great two-legged dinosaur of the mesozoic era. this type of plant eater grew to be fully twenty-five feet long. (after marsh.)] another remarkable type of two-legged dinosaur was much like the flesh eaters just described, but they were plant eaters. the largest of these grew to be feet long and to feet high, comparable, therefore, to the tyrannosaur in size. a wonderful collection of almost perfect skeletons may be seen in the museum in brussels, belgium. in mining coal , feet below the surface in belgium, twenty-two complete skeletons and several partial skeletons were found in an ancient river deposit of cretaceous age. a marvelously preserved specimen of one of these two-legged plant eaters found in wyoming, has been called a "dinosaur mummy" because the skin and much of the flesh of the creature had shriveled down upon its bones. the minutest details of the texture of its skin are almost perfectly preserved. [illustration: fig. .--skeleton of a dinosaur (triceratops) with a large remarkable head. this creature grew to be twenty-five feet long during cretaceous time. (after marsh.)] another type of dinosaur, so different from the others, should be briefly described. this was triceratops, or the "three-horned face" beast, so named because of the three powerful horns which projected forward from the top of the very large, flattened skull. it grew to be twenty to twenty-five feet long. skulls six to eight feet long have been unearthed. just where the brain might have developed, the skull dished downward, and so one authority considers triceratops to have had the largest head and smallest brain of all the great reptiles. it is well known that dinosaurs of many types lived during the great "age of reptiles," though by no means all types ranged through the whole era. no dinosaurs are definitely known to have crossed the line into the cenozoic era. one of the most astonishing facts in the history of animal life is the extinction of the mighty dinosaurs, but no very satisfactory explanation has yet been offered. probably their great size was a contributing factor, for it is well known "that while very large animals spend nearly all their time in eating, small animals spend a small proportion of theirs, and most of it in other activities. now, as long as food is abundant, the larger animals of a race have the better chances, but if a scarcity of food ensues, the larger animals may all be suddenly swept out of existence." (matthew.) whatever may have been the real reason for dinosaur extinction we can at least be sure "that with the extensive changes in the elevation of land areas (rocky mountain revolution) which mark the close of the mesozoic, came the withdrawing of the great inland cretaceous seas along the low-lying shores of which the dinosaurs had their home, and with the consequent restriction of old haunts, came the blotting out of a heroic race. their career was not a brief one, for the duration of their recorded evolution was twice that of the subsequent mammalian (cenozoic) age. they do not represent a futile attempt on the part of nature to people the world with creatures of insignificant moment, but are comparable in majestic rise, slow culmination, and dramatic fall to the greatest nations of antiquity." (schuchert.) among the most extraordinary animals not only of the mesozoic, but also of all time, were the flying reptiles or literal dragons of the air. some were very small, while others were the largest creatures which ever flew, with a spread of wing of twenty to twenty-five feet--twice that of any modern bird. unlike birds they had no feathers, but the two wings consisted of large membranes (batlike) supported by one enormously elongated finger of each front limb. the other fingers were armed with sharp claws. the early mesozoic flying reptiles had sharp teeth, while the later ones were mostly entirely toothless, but all were carnivorous. their short bodies were supplied with tails of varying lengths, one long-tailed species having a rudder at the end. their heads were fairly large, but of light build. the creature called "pteranodon" was not only the largest of the flying reptiles, but also probably the most highly specialized creature which ever lived, everything possible apparently having been sacrificed to facilitate flight (plate ). the hollow bones were so wonderfully light and strong that it has been estimated that the living animal, with twenty-five foot spread of wing, and head four feet long, could not have weighed more than twenty-five pounds! the rear portions of the body and hind limbs were very weak. [illustration: fig. .--a small carnivorous flying reptile of mesozoic time. spread of wings about two feet. (restored by marsh.)] it should not be thought that the above-described groups of reptiles were the only ones which existed during mesozoic time. there were also certain groups still living, like turtles, lizards, and crocodiles, but they were doubtless mostly completely under the dominance of certain of the now long-extinct types above described. the oldest-known fossil snakes are from very late mesozoic rocks, where they are small and comparatively rare. more than likely they evolved from lizards by deterioration of the legs. poisonous snakes were not evolved until early in the next (cenozoic) era. we shall now turn our attention to next to the highest class of vertebrate animals--the birds. they and the mammals are the only warm-blooded animals. what is their ancestry? from what original stock did they branch off? the oldest-known bird lived during the jurassic period, and it was so decidedly reptilian in character as to render it practically certain that birds are specialized descendants of certain mesozoic reptiles, though not, as might be supposed, of the flying reptiles. the few known specimens of the jurassic birds were found in the famous lithographic limestone quarries of bavaria. at least two of the specimens are in a marvelous state of preservation, with practically the whole skeleton intact and almost perfect impressions of the feathers on the rock. that the creature was really a bird is proved not only by its feathers, but also its beak, brain, limb bones, and feet. among the reptilian characters are its long, vertebrated tail, teeth set in sockets, and long claws on the wings. this reptilian bird was about the size of a small crow. by late cretaceous time the birds made notable evolutionary progress and they became diversified, more than thirty species being known from cretaceous rocks. these were distinctly more modern in structure and appearance than the jurassic bird. the only important reptilian characteristic still retained was the possession of teeth. the tail had become much shortened and the brain was still relatively smaller than in modern birds. one type, about nine inches high, was a powerful flier, as shown by the strong keel and wing bones. another important cretaceous type was almost wholly a water dweller, with powerfully developed legs used in swimming. its teeth were set in grooves instead of in sockets, thus indicating degeneration of tooth structure. this type was notable for its size--five to six feet in length. [illustration: fig. .--an early type of bird with teeth. this bird grew to a height of about nine inches in cretaceous time, millions of years ago. (restored by marsh.)] during the early part of the cenozoic era birds became still more advanced and numerous, with many modern groups represented. some of the more primitive types were, however, still left over during the tertiary, as, for example, a toothed bird, in which the teeth were merely dentations of the bill, thus being the most degenerate of all types of tooth structure. mammals comprise the highest class of all animals. they are, of course, all warm blooded and characterized by suckling their young. so far as known, mammal life began in the early mesozoic era as a branch of primitive reptiles, but they made little progress throughout the era when they occupied a very subordinate position in the animal world. they were few in number, small, and primitive in structure. there is no evidence for the mesozoic existence of any of the higher forms of mammals, that is, those which give birth to well-formed young which are prenatally attached to the mother by the so-called placentum. "during the eons of the mesozoic, from late triassic time until its close, the mammals (including the remote progenitors of humanity) were in existence, but held in such effective check (by reptiles) that their evolutionary progress was practically insignificant. this curb is strikingly illustrated by the wonderful series of tiny jaws and teeth of these diminutive creatures found in the comanchian (early cretaceous) of wyoming, in actual association with the single tooth of a carnivorous dinosaur, many times the bulk of the largest mammalian jaw. the removal of this check resulted (in the tertiary period) in the speedy evolution of the archaic mammals." (schuchert.) the phenomenal development of mammals during the tertiary period forms one of the most wonderful chapters in the whole evolution of organisms. even very early in the tertiary, many important higher (placental) types of mammals had evolved, and the simpler, more primitive mesozoic forms became very subordinate. by the close of the tertiary the higher types of mammals had become marvelously differentiated into most of the present-day groups or types. a very significant feature of the evolution was the steady increase in relative size of brain. the vast numbers of fossil skeletons and bones of mammals found in tertiary strata is scarcely believable. in our brief discussion we can do no more than describe a few representative examples of the cenozoic evolution of mammals. the great diversity of modern placental animals may be suggested by a few examples, as the tiger, dog, horse, camel, elephant, squirrel, hedgehog, whale, monkey, and man. forms like these, traced back through their ancestors to the very early part of the tertiary period, gradually become less and less distinct until they cannot be at all distinguished as separate groups, but rather there are ancestral generalized forms which show combinations of features of the later groups. those early tertiary generalized placental mammals had four feet of primitive character, with five toes on each foot; the whole foot, which from toe to heel touched the ground, was not adapted to swift running; the teeth were simple (primitive) in type and of full original number (forty-four); the toes were supplied with nails which were about intermediate between real claws and hoofs in structure; and the brain was relatively much smaller and simpler in structure than in most modern mammals. [illustration: fig. .--chart showing the main features of interest in the evolution of the horse family through several million years of the present (cenozoic) era of geologic time. (after matthew, american museum of natural history.)] the history of the horse family furnishes an excellent illustration of certain evolutionary changes among mammals. skeletons of many species, ranging from the early tertiary to the present, have been found in remarkable state of preservation representing every important change in the history of the horse family. a study of the chart will make clear some of the most striking changes which have taken place. the oldest member of the horse family represented on the chart was about the size of a small fox, with four toes and a degenerated fifth toe (splint) on the front foot, and three toes and splint on the hind foot. since the chart was made a still more primitive form, even more closely resembling the original five-toed ancestor, has been found. gradually the middle toe enlarged, while the others disappeared except the two splints or very degenerate toes still left in the modern horse. increase in size of the animal and brain capacity accompanied these changes. also the teeth underwent notable change, and two originally separate bones (radius and ulna) of the foreleg became consolidated into a single stronger bone. the even-toed hoofed mammals of to-day, like the deer, pig, and camel, are also the product of evolution much like that of the horse, except that two of the original five toes have been equally developed, while the others have either greatly degenerated, as in the pig, or disappeared entirely, as in the camel. the elephants, or trunk-bearing animals, illustrate a very different kind of evolution. they seem to have reached their climax of development in the late tertiary when they grew to be as much as feet high, and were more abundant and widespread over the earth than at any other time. the modern elephant, like the horse, has been traced back through many intermediate forms to its primitive early tertiary ancestry. some of the most important evolutionary changes took place in the head portion. the trunk is a highly developed form of snout, the earliest form of which was much like that of the modern tapir. the tusks are highly specialized and elongated teeth. during the earlier history the chin was very long and supported short tusks, so that there were then four tusks. carnivorous mammals, like tigers and wolves, and gnawers, like rats and squirrels, may also be traced back to generalized early tertiary types. another kind of evolution is well illustrated by certain mammals which, even in early tertiary time, so thoroughly adapted themselves to a water environment as to become whales, porpoises, etc. [illustration: fig. .--comparison of feet of monkeys and man.] the primates include the highest group of all vertebrates, and therefore of all animals. monkeys, apes, and man belong to the primates. there is no evidence whatever for the appearance of even the simplest and most primitive forms before the opening of the cenozoic era, but even very early in tertiary time, lemurs and primitive types of monkeys existed. later in the tertiary true monkeys and apes were common, and by the close of the period some apes were highly enough developed to strongly resemble certain of the oldest and most primitive types of man. we have, however, no positive knowledge of the existence of man in even the latest tertiary. in the light of much evidence in regard to the antiquity of man, it seems improbable that true human fossils will ever be found in rocks older than the quaternary, though if we are willing to descend (far enough in the human scale toward apes) it is not unlikely that man-apes may be discovered in very late tertiary rocks. the difficulty comes in the classification. where are we to draw the line between the higher apes and the lowest forms of man? but this very difficulty is one of the strongest arguments in favor of the organic evolution of man because practically all intermediate forms between true man and certain other high-grade primates are known from the strata. the following tabular summary of the geological history of man is based upon the work of most of the ablest students of the subject. ==========================+===============================+============== . homo sapiens |historic (bronze and iron) age.|modern (e.g., modern man) | | |neolithic ("recent stone") age |postglacial | (carefully shaped and |but | polished stone implements) |prehistoric --------------------------+-------------------------------+-------------- . homo primigenius |upper paleolithic ("ancient |late glacial (e.g., neanderthal | stone") age (rough bone | man) | and stone implements, cave | | frescoes, bone carvings, | | etc.) | |lower paleolithic ("ancient |middle glacial | stone") age (rude stone | | implements of so-called | | "river man") | --------------------------+-------------------------------+-------------- . early ancestral forms |possibly some very crude |early glacial (e.g., pithecanthropus | stone implements |and possibly erectus) | |late tertiary --------------------------+-------------------------------+-------------- of the early ancestral forms, that is, those which were rather distinctly man-apes, two will be very briefly referred to. one of these, known as _pithecanthropus erectus_, was a remarkable creature whose partial skeleton, consisting of the upper part of a skull, lower jaw, several teeth, and a thigh bone, was found in early quaternary deposits in java in . it was certainly a man-ape or possibly ape-man of low order, about - / feet high. the skull has a low crown, very receding forehead, and prominent brow ridges, but the brain capacity is cubic centimeters, as compared to cubic centimeters in ordinary higher apes, and nearly , cubic centimeters in the average modern man. the very recently extinct very low-type aborigines of tasmania had a skull capacity of , cubic centimeters. in the lower jaw of an anthropoid or manlike ape set with rather human teeth was found associated with very crude stone implements seventy-five feet below the surface in river-deposited sand in germany. it is of either early or middle glacial time and quite certainly represents a lower order creature than the oldest paleolithic man as described below. many bones and implements of paleolithic man (see above table) have been found mainly in river gravels and caves. the relative ages of paleolithic human bones and implements are best determined by the associated fossil animals. thus the most ancient truly human fossils are found directly associated with bones of very old types of elephants, rhinoceroses, and hippopotamuses which are definitely known to have lived during middle or early middle glacial (quaternary) time corresponding to early paleolithic time. a very conservative estimate would make the age of such very old human remains at least , to , years because the ice age was at least , years long. in a later human stage there are many associations with extinct animals like an older type of mammoth, cave bear, cave hyena, and others of later glacial time estimated at , to , years ago. last of all was the latest paleolithic stage corresponding to the close of the ice age, the human remains of which are found associated with reindeer and the latest mammoths which roamed in great numbers across europe. this was probably not more than , to , years ago. paleolithic man is so called because he fashioned stone weapons and implements. the structure of skull and skeleton shows him to have been a low-type savage, something over five feet high on the average, with a forward stooping carriage. the average paleolithic brain was not greatly inferior in size to that of modern civilized man, but it was not so highly organized and occupied a thick skull with much lower forehead and heavy brow ridges. the bushmen of australia and the recently extinct tasmanians are the nearest modern resemblances. many fine specimens of paleolithic man have been found, especially in cave deposits. that he was an expert hunter is proved by the great accumulation of bones of now extinct animals found in and about his haunts or camps, bones representing at least , horses having been found around a single camp site! [illustration: fig. .--comparison of skulls: a, paleolithic (neanderthal) man; b, modern man. (after woodward, british museum.)] only two among the many known paleolithic man localities will be briefly described. in the perigord district of southwestern france a number of caves contain human relics ranging in age from early to late paleolithic. of special interest among these relics are fishhooks made of bone, and crude sketches of animals such as the mammoth and reindeer now extinct in that region. the aurignac cave, also in france, was no doubt a family or tribal burial place. seventeen paleolithic human skeletons, associated with bones of extinct animals and crude art works, were found in the cave. near the entrance there were ashes and charcoal mixed with burned and split bones of extinct animals. certain of the caves occupied by late paleolithic man have their walls decorated with sketches and even colored pictures. these are, therefore, the oldest known art galleries. an excellent example is the cave at altamira in northern spain. "as we glance at the pictures one of the first things to impress us is the excellence of the drawing, the proportions and postures being unusually good.... the next observation may be that, in spite of this perfection of technique, there is no perspective composition--that is, no attempt to combine or group the figures.... it is also clear that the work of many different artists is represented, covering a considerable period of time. the walls show traces of many other paintings that were erased to make way for new work." (wissler.) [illustration: fig. .--sketch of a painting by paleolithic man found in a cave in west-central france. various animals, including the extinct mammoth elephant, are represented. (courtesy of american museum of natural history.)] the neolithic, or "recent stone" age was a gradual development from the late paleolithic, and man was then more highly developed and more similar in structure to modern man. his stone implements were more perfectly made, and often more or less polished and ground at the edges. "the remains of neolithic man are found, much as are those of the north american indians, upon or near the surface, in burial mounds, in shell heaps (the refuse heaps of their settlements), in peat bogs, caves, recent flood-plain deposits, and in beds of lakes near shore where they sometimes built their dwellings upon piles.... neolithic man in europe had learned to make pottery, to spin and weave linen, to hew timber, and build boats, and to grow wheat and barley. the dog, horse, ox, sheep, goat, and hog had been domesticated." (norton.) "man is linked to the past through the system of life, of which he is the last, the completing creation. but, unlike other species of that closing system of the past, he, through his spiritual nature, is more intimately connected with the opening future." (j. d. dana.) chapter xx mineralogy we are more or less familiar with the division of all materials of nature into the animal, vegetable, and mineral kingdoms. with slight exceptions minerals are the materials which make up the known part of the earth. in a very real sense, then, mineralogy is the most fundamental of the various branches of the great science of geology because the events of earth history, as interpreted by the geologist, are recorded in the mineral matter (including most rocks) of the earth. when we examine the rocky material or mineral matter of the earth in any region we find that it consists of various kinds of substances each of which may be recognized by certain characteristics. each definite substance (barring those of organic origin) is called a mineral. or, more specifically, a mineral is a natural, inorganic, homogeneous substance of definite chemical composition. according to this definition a mineral must be found ready made in nature, must not be a product of life, must be of the same nature throughout, and its composition must be so definite that it can be expressed by a chemical formula. all artificial substances, such as laboratory and furnace products, are excluded from the category of minerals. coal is not a mineral because it is both organic and of indefinite composition. a few examples of very common substances which perfectly satisfy the definition of a mineral are quartz, feldspar, mica, calcite, and magnetite. only two substances--water and mercury--are ordinarily liquid minerals. there are nearly a thousand distinct mineral species, and to them and their varieties several thousand names have been applied. it is a surprising fact that of the eighty or more chemical elements, that is substances which cannot be subdivided into simpler ones, only eight make up more than per cent of the weight of the crust of the earth, though, with one very slight exception, none of the eight exist as such in mineral form. the eight elements are oxygen (nearly per cent), silicon (over per cent), aluminum (over per cent), iron (over per cent), calcium (or "lime"), magnesium (or "magnesia"), sodium (or "soda"), and potassium (or "potash"). certain rock formations are made up essentially of but one mineral in the form of numerous grains as, for example, limestone, which consists of calcite (carbonate of lime). most of the ordinary rocks are, however, made up of two or more minerals mechanically bound together. thus, in a specimen of granite on the author's desk several distinct mineral substances are distinguishable by the naked eye. these mineral grains are from one to five millimeters across. most common among them are hard, clear, glassy grains called quartz; nearly white, hard grains, with smooth faces, called feldspar; small, silvery white plates, easily separable into very thin flakes, called mica; and small, hard, black grains, called magnetite. it is the business of the mineralogist to learn the characters of each mineral, how they may be distinguished from each other, how they may be classified, how they are found in nature, and what economic value they may have. it is an important part of the business of the geologist to learn what individual minerals combine to form the many kinds of rocks, how such rocks originate, what changes they have undergone, and what geological history they record. it is thus clear that the great science of geology is much broader in its scope than mineralogy. one of the most remarkable facts about minerals is that most of them by far have a crystalline structure, that is they are built up of tiny particles known as molecules. such crystalline minerals are often more or less regular solid forms bounded by plane faces and sharp angles, such forms being known as "crystals." how do crystals develop such regularity of form? any solid is considered to be made up of many very tiny (submicroscopic) molecules held together by an attractive force called cohesion. in liquids the molecules may more or less freely roll over each other, thus altering the shape of the mass without disrupting it. in gases the molecules are considered to be relatively long distances apart and moving rapidly. during the process of change of a substance from the condition of a liquid or gas to that of a solid, due to lowering of temperature or evaporation, the cohesive force pulls the particles (molecules) together into a rigid mass. under favorable conditions such a solid has a regular polyhedral form. "this results from the fact that the particles or molecules of the substance which, while it was liquid or gaseous, rolled about on one another, have been in some way arranged, grouped and built up. to illustrate this, suppose a quantity of small shot to be poured into a glass: the shot will represent the molecules of a substance in the liquid state, as for example a solution of alum. if, now, we suppose these same shot to be coated with varnish or glue so that they will adhere to each other, and imagine them grouped as shown in figure a, they will represent the arrangement of the molecules of the alum after it has become solid or crystallized. this arranging, grouping, and piling up of molecules is called crystallization, and the solid formed in this way is called a crystal. figures b and c show the shot arranged to reproduce two common forms of crystals (e.g., fluorite and calcite)." (whitlock.) [illustration: fig. .--piles of shot arranged to give some idea of the manner in which molecules are bound together in various crystal forms. (after whitlock, new york museum.)] a combination of certain facts regarding crystals furnish all but absolute proof of some sort of regularity of arrangement of particles within them. among such facts are the following: ( ) the wonderful regularity of arrangement of faces upon crystals is practically impossible to account for except as the outward manifestation of regularity of structure or systematic network arrangement of the interior; ( ) most crystals split or cleave more or less perfectly in one or more directions presumably in accordance with certain layered structure of the constituent particles; ( ) all of the many known forms of crystals can be accurately grouped in regard to their effects upon the passage of light (especially polarized light) through them, each kind or type of network structure presumably producing a different effect upon light; and ( ) x-ray photographs have proved that particles, or at least groups of particles, are very systematically arranged within crystals. it will be instructive for us to make a comparison between the growth of crystals and organisms. both really grow, but each species of organism is rather definitely limited in size while there is no known limit to the size which may be attained by a crystal so long as material is supplied to it under proper conditions. as a matter of fact crystals vary in size from microscopic to several feet in length, those less than an inch in length being most abundant by far. organisms mostly grow from within, while crystals grow from material externally added. it is an astonishing fact that in crystals as well as organisms growth takes most rapidly on a wound or broken place. thus if a crystal is removed from the solution in which it is growing and put back after a corner has been broken off, the fractured surface will build up more rapidly than the rest. finally, crystals are not necessarily limited in age like organisms. under certain natural conditions, as, for example, weathering, crystals may decay or be broken up; but where they are protected as constituent parts of rock formations well below the earth's surface they may remain unchanged for indefinite millions of years. thus in a ledge of the most ancient known or archeozoic rock only recently laid bare by erosion one may see crystals which are precisely as they were when they crystallized many millions of years ago. one of the most remarkable properties of a crystal is its symmetry, by which is meant the greater or less degree of regularity in the arrangement of its faces, edges, and vertices. a given substance may, according to circumstances, crystallize in a variety of forms or combinations of forms, but, with very few exceptions, all crystals of a given substance exhibit the same kind or grade of symmetry. there are three kinds of crystal symmetry, namely, in respect to a plane, a line or axis, and a point or center. a plane of symmetry divides a crystal into halves in such a way that for every point on one side of the plane there is a corresponding point directly opposite on the other side. crystals may be cut into halves along various surfaces which are not symmetry planes. an axis of symmetry is a line about which a complete rotation (or in a few cases rotation combined with reflection) brings the crystal into the same relative position two, three, four or six times, these being called two, three, four, and sixfold axes of symmetry--no others being possible. a crystal has a center of symmetry when any line passing through it encounters corresponding points at equal distances from it on opposite sides. there are just classes or combinations of the symmetry elements among crystals and just definite crystal forms. not only is it demonstrable that no more can exist, but actual experience with crystals of hundreds of species of minerals has never revealed any more. obviously, then, symmetry furnishes us with a very scientific basis of classification of crystals, all of the crystal forms constituting the symmetry classes being in turn referable to seven fundamental crystal systems. to bring out the relations of the faces of a crystal and further aid in classification, prominent, straight lines or directions passing through the center of a crystal are chosen as crystallographic axes. such axes may or may not coincide with symmetry axes. basing our definitions upon both symmetry axes and crystallographic axes, the seven systems are as follows: . isometric. there must be at least four threefold axes of symmetry, while the highest grade symmetry class of the five in the system includes three fourfold, four threefold, and six twofold axes of symmetry; nine planes of symmetry; and a center of symmetry. there are three interchangeable crystallographic axes at right angles to each other. [illustration: fig. .--figures showing, a, crystal axes of isometric system; b, points of emergence of the nine axes of symmetry in a cube of the isometric system; c, nine planes of symmetry in a cubic crystal. (after whitlock, new york state museum.)] . tetragonal. there must be one and only one fourfold symmetry axis, while the highest of its seven symmetry classes contains also four twofold axes of symmetry; five planes; and a center. characterized by three crystallographic axes at right angles to each other, only two of them interchangeable. . trigonal. characterized by one and only one threefold symmetry axis, the highest of the five classes having also three twofold axes; four planes; and a center. crystallographic axes as for hexagonal. . hexagonal. one and only one sixfold axis of symmetry must be present, but the highest of the seven classes also has six twofold axes; seven planes; and a center. characterized by four crystallographic axes, one vertical and three interchangeable horizontal axes making angles of degrees with each other. . orthorhombic. there must be no axis of symmetry higher than a twofold and three prominent directions (i.e., parallel to important faces) at right angles to each other, the highest grade of the three classes having three twofold axes; three planes; and a center. there are three noninterchangeable crystallographic axes at right angles. . monoclinic. there is no axis of symmetry higher than a twofold and only two prominent directions at right angles to each other, the highest of the three classes having one twofold axis; one plane; and a center. there are three noninterchangeable crystallographic axes, only two of which are at right angles. . triclinic. there is no axis of symmetry of any kind, and there are no prominent directions at right angles. one of the two classes has a center of symmetry only, and the other no symmetry at all. characterized by three noninterchangeable crystallographic axes, none at right angles. a fact which should be strongly emphasized is that crystals only, of all the objects of nature, can be definitely referred to the above seven systems comprising the classes of symmetry, and crystal forms. since there are about , mineral species and only fundamental forms, it necessarily follows that two or more species may crystallize in the same form within a class, so that it is not always possible to tell the species of mineral merely by its crystal form. it is, however, a remarkable fact that, where two or more substances crystallize in the same class (i.e., show the same grade of symmetry) each substance almost invariably exhibits "crystal habit" which is a pronounced tendency to crystallize in certain relatively few forms or combinations of forms out of the many possibilities. it is clear, then, that grade of symmetry combined with "habit" are of great practical value in determining crystallized minerals, because, on the basis of symmetry, a crystal is referred to a certain definite symmetry class in which only a limited number of substances crystallize, and then, by its characteristic "habit," the particular substance can be told. [illustration: fig. .--figures illustrating three crystal forms with exactly the same symmetry elements; a and b are separate forms, and c is a combination of the two. the mineral "garnet" nearly always crystallizes in one of these forms.] from the above discussion it should not be presumed that crystals always develop with perfect geometric symmetry. as a matter of fact such is seldom the case because, due to variations of conditions or interference of surrounding crystals in liquids (ordinary or molten), a crystal usually grows more rapidly (by building out faces) in certain directions than in others. under such conditions actual crystals are said to become distorted because they are not geometrically perfect. whether geometrically perfect or not, all crystals respond to the law of constancy of interfacial angles which means that on all crystals of the same substances the angles between similar (corresponding) faces are always equal. this is one of the most fundamental and remarkable laws of minerals. that it must be true follows from the fact that the crystal faces merely outwardly express in definite form the definite internal structure or arrangement of particles which have built up the crystal. in other words, the real structural symmetry of a crystal never varies no matter how much its geometric symmetry may vary. the practical application of the law of constancy of interfacial angles lies in the fact that in many cases a mineral may actually be identified merely by measuring the interfacial angles of its crystal form. the relative lengths of the crystallographic axes is a very important feature of all crystals except those of the isometric system in which the axes are always of equal length so that the ratio is : : . in all the other systems, however, at least one axis differs in length from the others and, since the amount of difference is absolutely characteristic of each substance, the axial ratio of a crystal, when carefully determined by measurement of the angles between the different faces, affords a never-failing method of determining the mineral for all systems except the isometric. by way of illustration, the tetragonal crystal of the mineral zircon, with only one axis different in length, shows the very definite axial ratio : : . , while the orthorhombic crystal of sulphur, with all three axes of different lengths, has an axial ratio . : : . . these ratios of course always hold true no matter what the size or particular outward form of the crystal. as might be expected from the above discussion of the remarkable structure of crystals, experience has proved that the relative lengths of all intercepts (or distances from the center) of all faces upon any crystal can be expressed by whole numbers, definite fractions, or infinity. it necessarily follows that the ratios between the intercepts of the faces of any face on a crystal to those of any other face on the same crystal may always be expressed by rational numbers, and this is known as the law of definite mathematical ratio. it is a remarkable fact that very small whole numbers or fractions, or infinity or zero, will always express the intercepts of any crystal face. thus far our discussion has centered about crystals as individuals, but, in most cases by far, they form groups or aggregates. most commonly crystal grouping is very irregular, but by no means rare is parallel grouping where whole crystals, or more usually parts of crystals, have all corresponding parts exactly parallel. but most remarkable of all are the twin crystals in which two or more crystals intergrown or in contact have all corresponding parts in exactly reverse order. the conditioning circumstances under which twin crystals develop are unknown. in the light of the facts and principles above explained, the reader will more than likely agree with the author that crystals rank very high among nature's most wonderful objects. but there are still other characteristic features of crystals naturally resulting from their marvelous structure. some of these will now be briefly referred to. [illustration: fig. .--figures illustrating twin crystals: a, gypsum (monoclinic system); b, fluorite (isometric system); c, cassiterite (tetragonal system). (after new york state museum bulletin.)] many crystals and crystalline substances exhibit the important property known as cleavage which is the marked tendency to break easily in certain directions yielding more or less smooth plane surfaces. as would be expected, a cleavage surface is always parallel to an actual, or at least a possible, crystal face, and it takes place along the surfaces of weaker molecular cohesion. the degree of cleavage varies from almost perfect, as in mica, to very poor or none at all, as in quartz. the number of cleavage directions exhibited by common minerals is illustrated as follows: mica, one; feldspar, two; calcite, three; and fluorite, four. it is a striking fact that when a crystal or cleavage piece is placed in a solvent, the action proceeds with different velocities in crystallographically different directions and little pits or cavities, called etching figures, are developed on some or all of the faces. since the symmetry of these etching figures and their arrangement upon the faces are directly related to, and natural effects of the crystal symmetry, the figures often furnish an important method of placing a doubtful crystal or even merely a cleavage fragment in its proper symmetry class. another marvelous property of crystals and crystalline substances is their effect upon light. since the study of the passage of light through crystals has really become a large separate branch of mineralogical study, we can no more than state a few fundamental facts and principles in the short space at our disposal. light is caused by vibrations of the so-called "ether," and always travels in straight lines. the vibration directions are at right angles to the direction of transmission of the light. when a ray of light enters a crystal or crystalline mineral representing any crystal system except the isometric it is doubly refracted (i.e., broken into two rays), each of the two rays is polarized (i.e., made to vibrate in a single plane only), and one ray vibrates almost at right angles to the other. double refraction is strikingly shown by placing a piece of clear calcite (iceland spar) over a dot on paper when two dots instead of one are visible. the amount of double refraction varies with the substance, and in some degree according to the direction of passage of light through a crystal. isometric crystals only are singly refracting and hence a ray of light is not affected in passing through them. crystals of all the other six systems doubly refract and polarize light and in three systems--tetragonal, hexagonal, and trigonal--one direction (coincident with the main axis of symmetry) produces single refraction only, while in the remaining three systems--orthorhombic, monoclinic, and triclinic--there are always two directions of single refraction whose positions vary with the substance. many crystals outside the isometric system also exhibit a remarkable tendency to absorb light differently in different crystallographic directions, thus producing two or three color tints, which vary according to the substance. after gaining a practical knowledge of the above and many other optical properties of crystals, it is possible by the aid of a specially constructed (polarizing) microscope, to recognize (with few exceptions) each one of the many mineral species. this method is of great value in determining the various minerals which are aggregated in the form of a rock, in which case a very thin slice of the rock is studied with the microscope. an important criterion for the recognition of minerals is hardness, by which is meant the resistance of a smooth surface to abrasion or scratching. the generally adopted scale of hardness follows: .--soft, greasy feel, and easily scratched by the finger nail (e.g., talc). .--just scratched by the finger nail (e.g., gypsum). .--just scratched by a copper coin (e.g., calcite). .--easily cut by a knife, but does not cut glass (e.g., fluorite). .--just scratches soft glass, and is cut by a knife (e.g., apatite). .--harder than steel, and scratches glass easily (e.g., orthoclase). , , , and .--harder than any ordinary substance and represented in order by quartz, topaz, corundum, and diamond. [illustration: plate .--skeleton of the great two-legged, carnivorous dinosaur reptile, called "tyrannosaurus," which lived during cretaceous time. (_courtesy american museum of natural history._) small picture.--restoration of the earliest known bird of which several nearly perfect skeletons have been found. this feathered creature with reptilian characteristics lived at least , , years ago. it had a long vertebrated tail, claws on the ends of the wings, and teeth. (_by e. w. berry._)] plate .--(_a_) skeleton of the largest known creature that ever flew. it was a flying reptile with spread wings of nearly twenty-five feet, and lived during the cretaceous period several million years ago. (_courtesy of the american museum of natural history._) plate .--(_b_) skeleton of a remarkable swimming reptile of the mesozoic era. length about twelve feet. parts of skeletons of unborn young are seen. (_courtesy of the american museum of natural history._) minerals also show a great variety of colors. many of them like quartz and calcite are colorless or white, others like galena (steel-gray) and pyrite (brass-yellow) show inherently characteristic colors, while still others like amethyst (purple) and sapphire (blue) are colored by impurities. there is also a great range in relative weights or density of minerals, commonly called the specific gravity, which range from less than one for ice to . for platinum, and even somewhat higher. the average specific gravity of all minerals of the earth is about . . in the light of the above discussion of the general properties of minerals, we shall now proceed to name and briefly describe some of the minerals which are either very common, or of special interest, or of special economic importance. only those features are listed by which the mineral species may be recognized at sight, or by the aid of very simple nonchemical tests. [illustration: fig. .--drawings showing forms of crystals of common minerals: a and b, garnet (isometric); c and d, feldspars (monoclinic); e, f, and g, quartz (trigonal); h, i, and j, calcite (hexagonal); k, augite (monoclinic); l. hornblende (monoclinic); m, pyrite (isometric).] amphibole. a number of species closely related in composition, crystal form, and properties are here included. they are silicates of lime and magnesia usually with aluminum and iron. most common by far are those which crystallize in the monoclinic system with prismatic faces and two good prismatic cleavages meeting at about degrees. color, commonly brown to black, but sometimes green or white. hardness varies from to , and specific gravity from to . . _hornblende_, the most common species, is a dark colored silicate of lime, magnesia, aluminum, and iron. it is one of the few most common of all mineral species, especially in igneous and metamorphic rocks. _tremolite_ is a white to light gray silicate of lime and magnesia found especially in metamorphic limestones. _actinolite_ is a green silicate of lime, magnesia, and iron especially common in certain metamorphic rocks. one kind of jade is an amphibole similar to tremolite and actinolite in composition, while the other kind is a pyroxene (see below). _jade_ is and has been highly prized in the east (especially in china) where it has been carved into many objects of exceptional variety and beauty. jade is probably the toughest (not hardest) of all minerals because of its wonderful microscopically fibrous structure. in color it is white, gray, and green. apatite. crystallizes in the hexagonal system with a six-sided prism usually capped at each end by a six-sided pyramid (see figure g). composition, a phosphate of lime. color variable, but mostly white, green, or brown. hardness of , or just enough to scratch soft glass. specific gravity, . . no good cleavage. tiny crystals are widely disseminated through many common rocks--igneous, metamorphic, and sedimentary. in certain metamorphic limestones excellent crystals a foot or more in length have been found. apatite, mostly in uncrystallized form, is the source of most of our phosphate fertilizers. azurite. an azure-blue hydrous carbonate of copper which crystallizes commonly in small monoclinic crystals. hardness, nearly , and specific gravity, nearly . commonly occurs in veins deposited by underground water. one of the great ores of copper, especially in arizona, chile, and australia. barite. a sulphate of barium crystallizing in orthorhombic prisms usually of tabular habit. white to light color shades. hardness, . ; specific gravity, . , which is notably higher than the average of light-colored minerals. three good cleavages parallel to principal crystal faces. a common and widely distributed mineral, especially in many vein deposits associated with certain ores. used in ground form to give weight to certain kinds of paper and cloth, and a barium compound used for refining sugar is made from it. [illustration: fig. .--crystal forms cf common minerals: a, galena (isometric); b, sphalerite (isometric); c, beryl (hexagonal); d, hematite (hexagonal); e, magnetite (isometric); f, barite (orthorhombic); g, apatite (hexagonal); h. sulphur (monoclinic); i, gypsum (monoclinic); j, chalcopyrite (tetragonal); k, fluorite (isometric); l, zircon (tetragonal); m, tourmaline (trigonal); n, corundum (hexagonal).] beryl. a silicate of aluminum and the rare chemical element beryllium. hexagonal crystals usually of very simple six-sided prismatic habit (see figure c). color white, green, blue, or yellow. specific gravity, . . cleavage practically absent. it is a very exceptionally hard mineral, being in the scale. very large crystals have been found, as, for example, in new hampshire, where single crystals several feet long weigh a ton or more. beryl is also of special interest because two of its varieties--_emerald_ (green) and _aquamarine_ (blue)--are well-known gem stones, the emerald being one of the most highly prized gems. the colors are due to slight impurities. beryl most commonly occurs in dikes of coarse granite called pegmatite, but also in certain metamorphic and sedimentary rocks. calcite. commonly called "calc spar." a carbonate of lime. hexagonal crystals in a great variety of forms, but all with crystal faces arranged in sixes around the principal or vertical axis forming rhombohedrons, prisms, or double-pointed pyramids. the principal axis of symmetry is sixfold by a combination of rotation and reflection. very perfect cleavages in three directions yielding fragments whose faces make angles of and degrees. color, white when pure, but variously colored when impure. hardness, (very easily scratched by a knife); specific gravity, . . calcite is a very common mineral, especially in limestone (including _chalk_) and marble which are usually largely made up of it. also commonly found in veins, and as spring and cave deposits (stalactites). a porous, stringy variety, called _travertine_, is deposited by certain hot springs, as at mammoth hot springs in yellowstone park. a very transparent crystalline variety is called _iceland spar_. calcite is a very useful mineral. limestone and marble are widely used as a building stone, and for decorative purposes, statuary, etc. limestone is burned for quicklime, used as a flux in smelting certain ores, in glass making, etc. cassiterite. the one great ore of tin whose composition is oxide of tin. tetragonal crystallization (figure c). hardness greater than steel, being over in the scale. specific gravity , which is notably high. color, brown to nearly black. cleavage, practically absent. fairly widespread in small amounts, and in commercial quantities in only a few localities, usually in veins in granite or metamorphic rocks near granite, as at cornwall, england, also in the form of rounded masses in gravel deposition as in the malay region. chalcocite. crystallizes in the orthorhombic system, usually in tabular form, but crystals not common. a black sulphide of copper with metallic luster. hardness, nearly ; specific gravity, nearly . no cleavage. chalcocite occurs in vein deposits as one of the important copper ores, especially at butte, montana. chalcopyrite. known as "copper pyrites," (figure j). a deep brass-yellow sulphide of iron and copper. seldom crystallized in tetragonal forms. hardness, . ; specific gravity, over . no cleavage. metallic luster. widely distributed in vein deposits associated with other metal-bearing minerals. a very important ore of copper, especially at rio tinto, spain. chlorite. a soft, green mineral, usually in small tabular crystals, in general appearance much like mica (see below), but unlike mica, the almost perfect cleavage leaves are not elastic, though they are flexible. composition, a silicate of aluminum and magnesia. always of secondary origin as a result of chemical alteration of certain other minerals, such as biotite-mica, pyroxene or amphibole. cinnabar. a vermilion-red sulphide of mercury. an extra soft metallic mineral, only . in the scale. specific gravity over , which is notably high. completely vaporizes on being heated. small trigonal crystals rare. cinnabar is the one great ore of mercury, occurring in veins, especially in california and spain. copper. copper as such (so-called "native copper") is widely distributed in veins, usually in small amounts with other copper minerals, but in the great mines of northern michigan it occurs in immense quantities as the only important ore. it is readily recognized by its color, softness (less than ), and notable weight (specific gravity, nearly ). isometric crystals uncommon. corundum. an oxide of aluminum of hexagonal crystallization, usually in six-sided prisms, capped by very steep pyramidal faces (see figure n). it is next to the hardest of all known minerals ( in the scale), the diamond only exceeding it. specific gravity about . three good cleavages making angles of nearly degrees with each other. the color of corundum is usually brown, but it varies greatly. two of the most highly prized of all precious stones--_ruby_ (red) and _sapphire_ (blue)--are nearly transparent varieties of corundum, colored by certain impurities. _oriental topaz_ (yellow), _oriental emerald_ (green), and _oriental amethyst_ (purple) are also clear varieties of corundum. it occurs in various igneous and metamorphic rocks, and in some stream gravels. the finest rubies, associated with some sapphires, occur in gravels in burma, siam, and ceylon. _emery_ is a fine-grained mixture of corundum and other minerals, especially magnetite. diamond. this mineral is remarkable not only because it is the king of precious stones, but also because it is easily the hardest known substance ( in the scale). specific gravity, . . very brilliant luster. crystals of usually octahedral habit in the isometric system. usually colorless, but often variously tinted. composition, pure carbon. burns completely away at high temperature. the greatest mines in the world are in south africa, where the diamonds occur in masses of rather soft (decomposed) igneous rock, evidently having crystallized during the cooling of the molten masses. in brazil and india diamonds are found in stream gravels. feldspar group. the feldspars are by far the most abundant of all minerals in the crust of the earth. (figures c, d.) there are several important species or varieties of feldspar with certain features in common as follows: crystal forms, either monoclinic or triclinic (closely resembling monoclinic), in prismatic forms whose faces usually meet at or near or degrees; two good cleavages at or near degrees, hardness at or near ; specific gravity, a little over . ; color, usually white, gray, or pink; and composition, silicate of aluminum with potash, soda, or lime. the two potash feldspars are _orthoclase_ and _microcline_, the former being monoclinic, with cleavages at exactly degrees, and the latter triclinic, with cleavages a little less than degrees. a kind of green microcline is known as _amazon stone_. the soda-lime feldspars go by the general name _plagioclase_. they are triclinic, with cleavages meeting at approximately degrees. very commonly one of the cleavage faces exhibits characteristic, well defined striations or fine parallel lines caused by multiple twinning during crystal growth. some of the common plagioclases are _albite_, a white soda feldspar, including most so-called _moonstone_; _oligoclase_, a usually greenish-white to reddish-gray soda-lime feldspar including _sunstone_; and _labradorite_, a lime-soda feldspar, usually gray to greenish-gray with a beautiful play of colors. the feldspars occur in all three great groups of rocks, but they have most commonly crystallized during the cooling of molten masses of igneous rocks. where many sedimentary rocks have undergone great change (metamorphism) under conditions of heat, pressure, and moisture, feldspars have very commonly formed. orthoclase and microcline feldspar are used in the manufacture of porcelain and chinaware. some special varieties of feldspar are cut or polished for semiprecious stones or decorative purposes. fluorite. a common mineral whose composition is fluoride of lime. (figure b.) isometric crystals, usually cubes with edges modified, are common. twinned cubes are also common. easily scratched by a knife (hardness, ), and specific gravity a little over . clear and colorless when pure, but variously colored, especially green, blue, yellow, and brown, due to impurities in solution during crystallization. remarkable because of its four good cleavages meeting at such angles as to permit good cleavage octahedrons to be broken out of crystals. fluorite is widely distributed, most commonly in vein deposits, often associated with metallic ores. occurs also as crystals in some limestones and igneous rocks. some fissure veins of fluorite in limestone in southern illinois are twenty to forty feet wide. used mostly as a flux in the manufacture of certain steel, in glass making, and in making enamel ware. galena. commonly as isometric crystals either as cubes or combinations of cubes and octahedrons. composition, sulphide of lead. (figure a.) color, lead-gray with metallic luster. hardness, . ; specific gravity high, . . very brittle. three excellent cleavages at right angles and parallel to the crystal faces of the cube. nearly all of the lead of commerce comes from the smelting of galena. it is mined in many parts of the world where it nearly always occurs in typical vein deposits often associated with sphalerite (see below). garnet group. the members of this very interesting mineral group very commonly occur in isometric crystallized forms, mostly twelve and twenty-four faced figures or both combined, as shown by figure . all the six species of garnets are silicates, mostly of aluminum usually with either lime, magnesia, or iron. cleavage, very imperfect or absent. hardness great, . to . , and specific gravity . to . , varying according to species. color also varies with composition, but most commonly red, brown, and more rarely yellow, black, and green. garnets are most common as crystals embedded in metamorphic rocks, especially highly altered strata. also occurs in many igneous rocks and in some sands. commonly used as a semiprecious stone, and also ground for use as an abrasive, especially in making a kind of sand (or garnet) paper. gold. gold as such ("native gold") is, in small amounts, really a very widely distributed mineral. it is characterized by its yellow color, softness (less than in the scale), great weight (specific gravity, over ), and extreme malleability. most of the commercial gold occurs in river gravels (so-called "placer deposits"), and in veins associated with the very common mineral quartz. graphite. commonly called "black lead," but it is not lead at all. its composition is pure carbon--the same as that of the diamond. we here have a very remarkable example of a single substance (carbon) which, according to circumstances, crystallizes in two distinctly different systems (diamond in isometric, and graphite in hexagonal) yielding very thin, flexible flakes; greasy in feel; and easily rubs off on paper. it weighs less than the average mineral (specific gravity, a little over ). good crystals of hexagonal tabular form are rare. the most natural home of graphite is in the metamorphic rocks, especially certain of the highly altered strata, where it occurs in the form of more or less abundant flakes, having originated from organic matter. some also occurs in igneous rocks and in veins. large quantities are made at niagara falls from anthracite by electricity. gypsum. monoclinic crystals common, usually of simple forms, as shown by figure i. sometimes twin crystals. composition, sulphate of lime. colorless or white when pure. can be scratched by the finger nail (hardness, ). specific gravity, . . three good cleavages, especially the prismatic, yielding cleavage plates with angles of and degrees. thin cleavage layers, moderately flexible. there are several varieties: ( ) _selenite_, which is clear, crystalline; ( ) _satin spar_, fibrous with silky luster; ( ) _alabaster_, fine-grained and compact crystalline; and ( ) _rock gypsum_, massive granular or earthy. gypsum is common and widespread especially among stratified rocks often as thick beds which have mostly resulted from evaporation of bodies of water containing it in solution, and often associated with salt beds. also occurs as scattering crystals in shales and clays, and in some veins. in greatest quantities it is burned to make plaster of paris. satin spar and alabaster are often cut and polished for ornaments, etc. (see figure a.) halite. common salt. composition, chloride of soda. isometric crystals, nearly always in cubes with three good cleavages at right angles, and parallel to the faces of the cube. hardness, . ; specific gravity, . . colorless to white when pure. characteristic salty taste. abundant and widespread, often as extensive strata in rocks of nearly all ages, having resulted from evaporation of inland bodies of salt water. also in vast quantities in solution in salt lakes and the sea. halite has many uses, as for example, cooking and preservative purposes, indirectly in glass making and soap making, glazing pottery, and in many ore-smelting and chemical processes. hematite.--one of the common and important iron oxides with less iron than magnetite and no water as has limonite. crystallizes in hexagonal forms. color, black, with metallic luster, when crystalline, otherwise usually dull red. hardness, about ; specific gravity, about . no cleavage. red streak when rubbed on rough porcelain. hematite is extremely widespread in rocks of all ages, especially in metamorphic and sedimentary rocks. some occurs as crystals in igneous rocks, and some in vein deposits. it is the greatest ore of iron in the united states, especially in minnesota, michigan, wisconsin, and alabama. kaolin. commonly called "china clay." composition, a hydrous silicate of aluminum. crystallizes in scalelike monoclinic forms, but usually forms compact claylike masses. hardness, a little over ; specific gravity, . . color when pure, white. usually feels smooth and plastic. very abundant and widespread, especially forming the main body of clay and of much shale. always of secondary origin, generally resulting from the decomposition of feldspar. it is the main constituent of chinaware, pottery, porcelain, tiles, bricks, etc. limonite. an important oxide of iron in composition like hematite except for its variable water content. never crystallized. hardness, about ; specific gravity, nearly . color, light to dark brown to nearly black. leaves a characteristic yellowish-brown streak when rubbed on rough porcelain. exceedingly common and widely distributed, always as a mineral of secondary origin as a product of weathering of various iron-bearing minerals. where accumulated in considerable deposits it is an iron ore of some importance. magnetite. one of the three important oxides of iron containing no water, and richer in iron than hematite. (see figure e.) commonly crystallizes in isometric octahedral forms alone or combined with twelve-faced forms. hardness, ; specific gravity, . color, black with metallic luster. leaves black streaks on rough porcelain. characteristically highly magnetic. wide-spread as crystals in nearly all kinds of igneous rocks, and as large segregation masses in certain igneous rocks. also very common in metamorphic rocks, in many cases forming lenses and beds as ore deposits. occurs in some strata and sands. it is an important ore of iron. malachite. a light-green hydrous carbonate of copper. in almost every way, except difference in color and slight difference in composition, it is very much like azurite (see above). mica group. the micas rank high in abundance among the most common minerals of the earth. all of the several species are silicates of aluminum combined with other chemical elements according to the species. all crystallize in monoclinic six-sided prisms whose angles are nearly degrees. these prisms closely approach true hexagonal forms. all are characterized by one exceedingly good cleavage at right angles to the prismatic faces, yielding very thin elastic cleavage sheets. hardness, to . ; specific gravity, . to . the various species or varieties are not always sharply separated from each other. most common are: _muscovite_, or so-called _isinglass_, a potash mica which is colorless and transparent in thin sheets when pure; _biotite_, an iron-magnesia mica, black to dark green; and _phlogopite_, a brown magnesia mica. olivine. often called _chrysolite_. a silicate of iron and magnesia. orthorhombic crystals, usually in stout prismatic form. color, usually yellowish green. hardness, nearly ; specific gravity, . . transparent to translucent. no real cleavage. its hardness, color, and crystal form generally characterize it. it is a fairly common mineral found mainly as crystalline grains in certain dark-colored igneous rocks. a clear green variety, called _peridot_, is used as a gem stone. opal. an oxide of silicon, like quartz in composition except that it is combined with a varying amount of water. it never crystallizes, probably because of its rather indefinite composition. hardness . to . (softer than quartz); specific gravity, about . varieties variously colored. _common opal_, usually translucent with greasy luster. _precious opal_, translucent with beautiful play of colors, used as a gem. _fire opal_, with bright red to orange internal reflections. _hyalite_, colorless and transparent in small rounded masses. _wood opal_, wood petrified by opal. _geyserite_, a white, porous, stringy variety deposited by certain hot springs like the yellowstone geysers. _tripolite_, fine-grained, chalklike in appearance, consisting of tiny siliceous shells of very simple plants called diatoms. platinum. this mineral occurs as an impure native metal, usually alloyed with certain other metals. native platinum, hardness, . (exceptionally high for a metal); specific gravity as usually alloyed, to . pure platinum, specific gravity, over , or one of the very heaviest known substances. color, light steel-gray, with metallic luster. very malleable and ductile. a rare metal found commercially mostly in gravel or "placer" deposits mostly in the ural mountains, also as grains in certain dark igneous rocks. used for many scientific instruments, in the electrical industry, as jewelry, etc. pyrite. commonly called "iron pyrites." sometimes called "fool's gold." (see figure m.) a sulphide of iron which commonly crystallizes in the isometric system mostly as cubes, twelve-faced pyritohedrons, octahedrons, or combinations of these. color, light brass-yellow, with metallic luster. cleavage, practically absent. hardness, greater than that of steel (over in the scale); specific gravity, about . leaves greenish black streak when rubbed on rough porcelain. differs from chalcopyrite by paler color and much greater hardness. it is a common and very widely disseminated mineral in rocks of all kinds and ages, but especially in metamorphic rocks as veins, and banded or lenslike deposits. most igneous rocks contain small scattering grains of pyrite. many deposits of commercial value are known. great quantities are burned for the manufacture of sulphuric acid ("oil of vitriol") which is one of the most important of all chemicals. pyroxene group. along with quartz and feldspars, the pyroxenes rank among the most common of all minerals. (see figure k.) composition, very similar to amphibole (see above). pyroxenes crystallizing in the monoclinic system are the most important. these crystals are prismatic in habit, with prism faces making angles of nearly or degrees instead of about degrees as in the monoclinic amphiboles which the monoclinic pyroxenes greatly resemble. two fairly good prismatic cleavages cross at an angle of nearly degrees, instead of at about degrees as in the monoclinic amphiboles. hardness, to ; specific gravity, . to . . color, variable according to species. the most common variety of pyroxene is _augite_, a dark-green to black silicate of aluminum, iron, lime, and magnesia. certain pyroxenes also crystallize in the orthorhombic system. pyroxene is most abundantly represented as crystals in many kinds of igneous and metamorphic rocks. it is practically useless except as one kind of _jade_. quartz. next to the feldspars, quartz is probably the most common of all minerals, especially at and near the earth's surface. (see figures e, f, and g.) composition, oxide of silicon. often crystallizes in the trigonal system almost always as six-sided prisms capped by six-sided pyramids, which are really combined three-sided forms, often with alternate corners modified by small faces. these small modifying faces, etching figures, and microscopic tests show that quartz is really trigonal in spite of the common occurrence of simple six-sided outward forms. the pyramidal faces make different angles than those of either apatite or beryl, both of which are somewhat like quartz in crystal form. hardness, (distinctly high, cannot be scratched by the knife); specific gravity, . (about average for all minerals). cleavage, practically absent, and breaks like glass. colorless when pure, but varieties exhibit many colors. a few only of the many varieties will be briefly described. among the distinctly crystalline varieties are: _rock crystal_, pure colorless; _amethyst_, purple; _rose quartz_, pink; _milky quartz_, white; and _smoky quartz_, dark--due to tiny inclusions of carbon. among the fine-grained, compact more or less indistinctly crystalline or noncrystalline varieties, usually translucent with a waxy luster, are: _chalcedony_, bluish gray, waxy looking, usually in small rounded masses; _carnelian_, red; _prase_, green; _agate_, with parallel bands, usually variously colored; _flint_ and _jasper_, opaque to translucent, dark to red. quartz is exceedingly abundant in all the great groups of rocks. it constitutes the main bulk of sandstones, is common in shales, and occurs in certain other strata. in many igneous rocks, like granite, it is a very prominent constituent. most of the metamorphic rocks contain its crystalline forms in greater or less amounts. quartz is the most common of all vein minerals, in many cases associated with valuable ores. various varieties are widely used for ornamental purposes. used in making sandpaper, glass, porcelain, mortar, concrete, and in certain ore-smelting processes. sandstone is widely used as a building stone. serpentine. a hydrous silicate of magnesia never in distinct crystals as such, but shown to be monoclinic under the microscope. hardness variable, . to ; specific gravity, about . . mostly of variegated green or yellowish green color with waxy luster, except a fibrous variety (_asbestos_) which is light green to white. the fibrous variety of serpentine is the principal source of asbestos, an amphibole asbestos being less common. ordinary serpentine (sometimes miscalled "green marble") is widely used as a building and decorative stone. serpentine is common and widespread, especially in igneous and metamorphic rocks, but never as a really original mineral. it always results from alteration of certain other magnesia-bearing silicate minerals, such as pyroxene, amphibole, olivine, etc. silver. native silver is not a very rare mineral and it is mined in certain parts of the world, but most of the metal is obtained from certain silver-bearing minerals, especially sulphides and a chloride. silver crystallizes rather rarely in the isometric system. more commonly it occurs as irregular masses, plates, and wirelike forms. characterized by its color, metallic luster, softness (less than in the scale), and exceptional weight (specific gravity, . ). usually occurs in vein deposits, commonly associated with other metals or metal-bearing minerals, especially copper. sphalerite. a sulphide of zinc commonly in crystalline form belonging in the isometric system, especially in tetrahedral combination forms (see figure b). color, usually brown, yellow or nearly black with resinous luster. hardness, nearly ; specific gravity, . several good cleavages, yielding fragments whose faces meet at and degrees. sphalerite is a fairly common and widespread mineral, occurring nearly always in veins in most kinds of rocks. it is very often associated with other ores, particularly the great ore of lead (galena). sphalerite is by far the greatest ore of zinc. sulphur. native sulphur. crystallization, orthorhombic, usually in combination pyramidal forms. (see figure h.) characterized by yellow color, resinous luster, softness (about in the scale), low specific gravity (about ), and very poor cleavages. it has most commonly resulted from alteration of certain sulphur-bearing minerals, especially gypsum, the decomposition of which has yielded vast deposits. some also of volcanic origin. great quantities are used in making sulphuric acid, matches, gunpowder, fireworks, and for vulcanizing and bleaching rubber goods. talc. often called _steatite_. monoclinic crystals rare. one perfect cleavage, yielding very thin, flexible leaves. very soft (hardness, ). feels greasy, and looks waxy to pearly. color, white, gray, to light green. specific gravity, . . composition, a hydrous silicate of magnesia, much like that of serpentine. talc is always of secondary origin, generally derived by chemical alteration of various common minerals rich in silicate of magnesia. _soapstone_ is a common variety resulting from alteration of whole rock masses. soapstone has many practical uses as for washtubs, table tops, electrical switchboards, hearthstones, stove and furnace linings, blackboards, gas tips, etc. talc proper is used as a lubricant, to weight paper, in soap, as dustless crayon, talcum powder, etc. topaz. a silicate of aluminum and fluorine. orthorhombic crystals common, usually prisms capped at one end by pyramided faces and abruptly terminated at the other. colorless when pure, but often variously colored due to impurities. very exceptionally hard ( in the scale); specific gravity, . . one good cleavage across the prism zone; usually found as crystals in, and in cavities in, igneous rocks. appears always to have formed from highly heated vapors or liquids given off by cooling molten rock masses. topaz is one of the more highly prized of the gem stones. tourmaline. composition, very complex, but chiefly a silicate of boron and several metals and semimetals. commonly as crystals in the trigonal system in both long and short prismatic forms, as shown by figure m, with opposite ends not unlike. extra hard ( in the scale); specific gravity, about . color, widely various, but brown and black are most common. practically no cleavage. tourmaline probably always originated as a high temperature mineral, especially as crystals in granites and related rocks and in certain metamorphic rocks which have been subjected to high temperature and pressure. certain transparent colored varieties of tourmaline rank high among the semiprecious stones. turquoise. a hydrous phosphate of aluminum. massive noncrystalline, blue to green, waxy luster, mostly opaque, hardness of , and specific gravity of about . . turquoise is a high temperature mineral found in veins and cavities in certain igneous rocks. it is a rare mineral used as a gem stone. zircon. a silicate of zirconium usually crystallized in the tetragonal system as simple four-sided prisms capped by four-sided pyramids. (see figure l.) very poor cleavages. color usually brown. hardness, . (extra high); specific gravity, nearly . . brilliant luster. zircon is very commonly present as scattering crystals of varying size in most igneous rocks. also common as crystals in various metamorphosed stratified rocks, and less common in some sand and gravel deposits. certain transparent varieties, especially the brown and pink ones called _hyacinth_, are used as gem stones. zircon is also the source of oxide of zirconium used in making mantles for certain incandescent lights. chapter xxi economic geology in this chapter it is our purpose to briefly consider geology in its direct relations to the arts and industries. when we realize that the value of strictly geologic products taken from the earth each year in the united states alone amounts to billions of dollars, we can better appreciate the practical application of geological science. such products include coal, petroleum, natural gas, many valuable metal-bearing minerals, and many nonmetalliferous minerals and rocks. in most cases these valuable products of nature have been slowly accumulated or concentrated at many times and under widely varying conditions throughout the millions of years of known geological time. to trace the extent of, and most advantageously remove, such deposits for the use of man is always invariably impossible unless geological knowledge is brought to bear. in many cases the problems involved are intricate, and only the trained geologist is able to at all successfully cope with them. in such cases it is necessary not only to have a thorough knowledge of minerals and rocks as such, but also of their origin and structure. much of the practical application of geology is carried out by the mining engineer who should have, above all, a thorough knowledge of the great principles of geology. our plan of discussion is to consider, first, coal, petroleum, and natural gas; then the most important metalliferous deposits of ores; and finally nonmetalliferous minerals and rocks of exceptional commercial importance. underground waters have already been discussed from the practical standpoint in the chapter on "waters within the earth." certain minerals have already been sufficiently considered from the economic standpoint in the chapter on "mineralogy." coal, petroleum, and natural gas coal. most valuable of all geological products is coal. although it is not, strictly speaking, a mineral, both because of its organic origin and lack of definite chemical composition, coal is generally classed among our mineral resources. some idea of the national importance of coal in the united states may be gained when we realize that the energy derived from a single year's output is equivalent to that of hundreds of millions of men working full time through the year. the uses of coal are too well known to need mention here. coal is, beyond question, of organic (plant) origin as shown by its very composition; perfect gradations between plant deposits like peat and true coal; and the presence of microscopic plant remains and spores in the coal. an excellent summary of just what happens during the transition of ordinary vegetable matter into coal has been given by d. white as follows: "all coal was laid down in beds analogous to the peat beds of to-day. all kinds of plants, especially such species as were adapted to the particular region where the deposit was located, in whole or in part went into the deposit. "plants are composed chiefly of cellulose and proteins. the former, comprising by far the larger bulk, constitute the framework, whereas the latter are concerned in the vital functions. with these are associated many other substances, among which are chiefly starch, sugars, and fats and oils, constituting reserve foodstuffs; waxes, resin waxes, resins, and higher fats, performing mainly protective functions.... these components differ widely in their resistance to various agencies. those substances involved in the life function and the support of the plant are relatively very stable under the conditions imposed upon them. "at the death of the plants, governed by conditions imposed in the bog, a partial decomposition, maceration, elimination, and chemical reduction begins, brought about by various agencies, chiefly organic, mainly fungi at first and bacteria later. the most labile are removed first, the more resistant next, and so on, as the conditions require, leaving the most resistant behind in a residue called peat. "the process of decomposition, elimination, and chemical reduction begun in peat, chiefly by biochemical means, is taken up and continued by dynamochemical means into and through the various successive later stages, and results in the various grades of coal, as lignite, sub-bituminous, and cannel coal, and anthracite." the principal chemical elements involved in the changes which take place are carbon, oxygen, and hydrogen, as shown by the following analyses of about average samples of each member of the so-called "coal series." =========================+========+========+==========+========= the "coal series" | carbon | oxygen | hydrogen | nitrogen -------------------------+--------+--------+----------+--------- wood (cellulose) | | | | peat | | | | lignite | | | . | . bituminous coal | | | | . anthracite coal | | . | . | trace graphite | | .. | .. | .. -------------------------+--------+--------+----------+--------- from this table it is seen that the oxygen relatively diminishes while the carbon relatively increases, though, of course, all three elements actually decrease during the chemical change from cellulose to coal. these three elements disappear mainly in the form of gases, such as water vapor, marsh gas, and carbonic acid gas. the final or graphite stage is almost reached by the graphitic anthracite of rhode island, which is so nearly pure carbon as to be really useless as coal. the conditions under which successive layers of vegetable matter (later turned into coal) become embedded in the earth's crust have been outlined in the chapter on the "evolution of plants." the most perfect conditions for prolific plant growth, and accumulation as great beds in the earth's crust, were during the pennsylvanian period of the late paleozoic era in many parts of the world, but especially in the united states, china, great britain, and germany. most of the world's great supply of coal comes from rocks of pennsylvanian age, while next in importance are cretaceous rocks, and some comes from strata of other ages later than the pennsylvanian, even as late as the tertiary. the united states not only has the greatest known coal fields, but it also produces far more coal than any other country. in the production was , , tons, the greatest in our history, or enough, if loaded into cars of forty tons capacity, to fill a train which would reach around the earth at the equator about six times! equally amazing is the fact that this coal was nearly all consumed by this one nation! in the production fell to , , tons. is there real danger that our supply of coal will soon run out? hardly so when we consider, first, the fact that probably not more than per cent of the readily available coal has thus far been removed, and, second, the high probability that rate of increase in coal production for the last twenty years will not continue. in fact, during the last two or three years the production has fallen off considerably. but even so, coal, which is our greatest natural resource, and which can never be replaced, should be scientifically conserved. in the case of the very restricted anthracite coal fields what might be called a crisis has already been reached, because a very considerable part of the available supply has been taken out. something like , square miles of the united states are underlain with one or more beds of workable coal (not including lignite)--in some areas five to twenty or more beds one above the other. there are also about , square miles of country underlain with the more or less imperfect coal called lignite. it has been estimated that there are more than a trillion tons of easily accessible coal, and another trillion tons accessible with some difficulty in the principal coal fields of the united states. the greatest production of coal by far is from the appalachian mountain and allegheny plateau districts, from the western half of pennsylvania to alabama, where all the coal is bituminous of pennsylvanian age. here as well as elsewhere the coal beds are interstratified with various kinds of sedimentary rocks, most commonly with shales and sandstones. in the appalachian field the strata including coal beds are more or less folded toward the east, while they are nearly horizontal toward the west. the famous pittsburgh coal bed is probably the most extensive important single coal bed known. it covers an area of over , square miles and is workable, with a thickness of five to fifteen feet, over an area of , square miles of parts of western pennsylvania, ohio, and west virginia. [illustration: fig. .--map of the united states, showing the principal coal fields. cross-lined areas represent lignitic coals. (after u. s. geological survey.)] the greatest production of anthracite coal by far is from central-eastern pennsylvania, where strata of pennsylvania age, including a number of anthracite beds, are mostly highly folded. most remarkable of all in this district is the so-called "mammoth bed" of anthracite, nearly everywhere present, with a thickness up to as much as fifty or sixty feet. less than square miles are there underlain by workable anthracite coal. next to the greatest production of coal in the united states is from the two large areas in the middle of the mississippi valley. it is all bituminous coal, associated with nearly horizontal strata of pennsylvanian age. the scattering areas through the rocky mountains yield all types of coal--anthracite, bituminous, and lignite. in some of these areas the coal beds have been but little disturbed from their original horizontal position, but usually they are more or less folded along with the inclosing strata, the crustal disturbances affecting the coal beds having taken place late in the mesozoic era and early in the cenozoic era. practically all of these coals are of cretaceous and tertiary ages, the best being cretaceous. very little of the rocky mountain coal is anthracite. on the pacific coast coal production is relatively very small. the coals are there bituminous to lignitic of tertiary age, usually folded in with the strata. in alaska there are widely distributed, relatively small coal fields, but they have been little developed. alaskan coals range in age from pennsylvanian to tertiary, and in kind from anthracite to lignite. petroleum. crude oil or petroleum is an organic substance consisting of a mixture of hydrocarbons, that is, it is made up very largely of the two chemical elements carbon and hydrogen, in rather complex and variable combinations. it is practically certain that petroleum has been derived by a sort of slow process of distillation from organic matter--animal or vegetable or both--in stratified rocks within the earth. many strata, as for example carbonaceous shales, are more or less charged with dark-colored decomposing organic matter. the chemical composition itself, the kinds of rocks with which it is associated, and certain optical (microscopic) tests all point to the organic origin of petroleum. in southern california at least, certain of the oils have quite certainly been derived from the very tiny oily plants called diatoms which fill many of the strata. [illustration: fig. .--profile and structure section showing folding of strata, with included coal beds, across one of the anthracite coal fields of eastern pennsylvania. length of section, a little over miles. (after u. s. geological survey.)] during the last twenty years petroleum has come to be one of the most important and useful natural products. among the many substances artificially derived from petroleum are kerosene, gasoline, naphtha, benzine, vaseline, and paraffine. the united states leads in the production of petroleum, while southern russia and mexico are very important producers. in the united states the principal areas underlain with petroleum-bearing strata are the northern appalachian field (through western pennsylvania to central west virginia); the ohio-indiana field (central indiana to northwestern ohio); the mid-continental field (southeastern kansas and northeastern oklahoma); the southeastern texas-louisiana field; and the southwestern california field. the total areas underlain with oil total about , square miles. in the appalachian, ohio-indiana, and mid-continental fields the strata carrying oil range in age from ordovician to pennsylvanian, and they are mostly but little disturbed from their original horizontal position. the texas-louisiana oils come mainly from cretaceous and tertiary strata which gently downtilt under the coastal plain toward the gulf. in california the oil-bearing strata are of tertiary age and generally considerably disturbed and folded. under proper conditions below the earth's surface the derived oil accumulates in porous or fractured rocks. there must, of course, be a source from which the petroleum is derived or distilled; a porous or fractured rock formation to take it up; a cap rock or impervious layer to hold it in; and a proper geologic structure to favor accumulation. the most common porous (containing) rock is sandstone, and the most common cap rock is shale. oil is rarely found without gas, and saline water is likewise often present. if the containing strata are horizontal, the oil and gas are usually irregularly scattered, but if tilted or folded, and the beds porous throughout, they appear to collect at the highest point possible. it was the result of observations along this line that led i. c. white to develop what is known as the "anticlinal theory." according to this theory, in folded areas the gas collects at the summit of the fold (anticline), with the oil immediately below, on either side, followed by the water. it is, of course, necessary that the oil-bearing stratum shall be capped by a practically impervious one. [illustration: fig. .--map showing the principal petroleum and natural gas fields of the united states. (after u. s. geological survey.)] [illustration: fig. .--a vertical (structure) section showing a very common type of oil-bearing structure. in this anticline, water, oil, and gas arranged in order of their specific gravities. removal of the gas would allow the oil and water to rise higher toward the apex of the porous layer. (after indiana geological survey.)] [illustration: plate .--general view in the appalachian mountains along new river, virginia. this is a typical portion of the great area which, during mesozoic time, was reduced by erosion to the condition of a low-lying plain ("peneplain"). since early cenozoic time the peneplain has been upraised and new river has carved out its v-shaped valley to its present depth, while tributary streams have carved out a series of valleys along belts of weak rocks nearly at right angles to the main valley. the remarkably even sky line marks approximately the old peneplain surface. (_photo by hillers, u. s. geological survey._)] [illustration: plate .--(_a_) a big glacial bowlder of plutonic igneous rock carried miles from its parent ledge by the ice sheet which passed over the adirondack mountains during the ice age. (_photo by the author._)] [illustration: plate .--(_b_) a long, winding ridge of sand and gravel (called an "esker") deposited by a stream in a channel in the ice near the margin of the great glacier during its retreat from the adirondack mountains. (_photo by the author._)] "if the rocks are dry, then the chief points of accumulation of the oil will be at or near the bottom of the syncline (downfold), or lowest portion of the porous bed. if the rocks are partially saturated with water, then the oil accumulates at the upper level of saturation. in a tilted bed, which is locally porous, and not so throughout, the oil, gas, and water may arrange themselves according to their gravity in this porous part." (ries.) although the term "oil pool" is commonly used, there is really no actual pool or underground lake of oil, but rather porous rock saturated with oil. it has been estimated that in an oil field of average productiveness a cubic foot of the porous rock contains from six to twelve pints of oil. the life of a well drilled into an "oil pool" varies from a few months to twenty or thirty years, or sometimes even more, but a heavy producer (especially a "gusher") almost invariably falls off very notably in production in a few months, or at most a few years. the typical pennsylvanian oil well is said to last about seven years. the fact that the united states is still able to increase oil output is because new fields are found and developed, the most recent being in the interior and northern parts of texas. it is practically certain, however, that the climax of oil production in the united states will be reached before many years--long before that of bituminous coal. it is a well-known fact that oil, as well as natural gas, is usually under more or less pressure within the earth. the pressure is so great in some cases that where, in the course of drilling, oil or gas accumulated under proper conditions, as for example those shown by figure , are encountered the pressure may be hundreds of pounds per square inch, or enough to blow to pieces much of the drilling outfit. it is under such conditions that great "gushers" are struck. a wonderful case in point was the famous lakeview gusher, struck in california in . "within a few days the well was far beyond control. it continued to flow (for a time shooting high into the air) for eighteen months, finally stopping after it had produced over , , barrels of oil, about , , of which had been saved. the daily production of the well varied greatly, reaching a maximum of , barrels." (pack.) one very common cause of oil pressure is the expansive force of the associated imprisoned gas which steadily increases as the gas is generated. another cause which is seemingly applicable in many cases is hydrostatic pressure, where under certain structural conditions the pressure of water in a long-tilted layer is exerted against oil accumulated toward the top of an anticline (or upbend) in the strata. the world's output of petroleum for was nearly , , barrels, of which the united states produced nearly , , barrels, mexico , , barrels, and russia , , barrels of gallons. natural gas. the most perfect fuel with which nature has provided us is natural gas. not only is it easily transported even long distances through pipes, but also as a fuel it is easily regulated, leaves no refuse, and is less damaging to boilers than coal. it is a colorless, odorless, free-burning gas, consisting very largely of the simple hydrocarbon called marsh gas or fire damp. petroleum nearly always has more or less natural gas associated with it, but in some cases considerable quantities of gas may exist alone. natural gas, like petroleum, is of organic origin--a product of slow natural distillation of vegetable or animal matter, or both, within the earth's crust. one of the most common modes of occurrence of gas is at the top of an anticline (upfold) in porous rock (like sandstone) between impervious layers (like shale). figure well illustrates the principle, the gas lying above the oil, and the oil above the water; that is, the three substances are arranged according to specific gravity. gas may also exist in considerable quantities in irregular bodies of porous or fractured rocks. natural gas is nearly always under pressure within the earth, hundreds of pounds per square inch being common, while more exceptionally, as in certain west virginia wells, pressures of over , pounds have been registered. the united states is by far the greatest world producer of natural gas, the output for having been , , , cubic feet. west virginia easily headed the list, with oklahoma and pennsylvania next in order. areas underlain with natural gas are, in the main, the same as for petroleum, and they total more than , square miles. during the last forty years the waste of natural gas in the united states has been appalling. in many cases wells in quest of oil have encountered gas and often such abandoned wells have been allowed to play millions of cubic feet of gas daily into the air for years. a striking example was the murraysville well of western pennsylvania, which shot , , cubic feet of gas per day into the air for six years! metal-bearing (ore) deposits iron. without question the most useful of all metals is iron. as such it is rare in nature, but in chemical combination with other substances it is extremely widespread and very common. iron makes up about per cent of the weight of the earth's crust, but in the form of ore (i.e., a metal-bearing mineral or rock of sufficient value to be mined) it is notably restricted in occurrence. the three great ores of iron are the minerals hematite, magnetite, and limonite, whose composition and characteristic properties the reader will find stated in the preceding chapter on "mineralogy." one of the worst impurities in iron ore is phosphorus, which makes iron "cold short," i.e., brittle when cold. ore for the manufacture of bessemer steel must contain very little phosphorus (less than / of the metallic iron content of the ore). sulphur as an impurity in the ore tends to make the iron "hot short." silica (quartz) is bad because it necessitates the use of more lime for flux in the furnace. iron ores occur in rocks of most of the great geologic ages, but in the united states principally in the pre-paleozoic and paleozoic. the united states is by far the greatest producer of iron ore in the world, the output for having been about , , tons, the greatest in the history of this or any other country. this one year's output loaded into cars of tons capacity would have made a train about , miles long! all but about , , tons of this tremendous production was hematite ore. in the output of iron ore dropped to about , , tons. [illustration: fig. .--drawing showing details of part of an ore-bearing vein at pinos altos, new mexico. the chalcopyrite and sphalerite are the ores. somewhat reduced in size. (after paige, u. s. geological survey.)] we shall now very briefly consider several of the greatest iron-mining districts of the united states, giving some idea of the modes of occurrence and origin of the ores. greatest of all is the lake superior region, not far west and south of the lake in minnesota, michigan, and wisconsin. considerably more than one-half the iron ore mined in the united states comes from the single state of minnesota, and about one-fourth of it from michigan. most of the minnesota ore by far is obtained from the so-called "mesaba range," which in produced , , tons of hematite ore. the ore deposits are there of irregular shape, lying at or near the surface (usually covered only by glacial deposits). none of them extend downward more than a few hundred feet. the soft, high-grade ore is removed by steam shovels in great open pits. in the several districts of northern michigan and wisconsin the ores (nearly all hematite) are associated with more or less highly folded rocks at considerable depths. the lake superior iron ores all occur in rocks of archeozoic and proterozoic ages. according to the best explanation of their origin the iron of the ores was once part of a sedimentary series of rocks in the form of iron carbonate and silicate, interstratified with layers of a flintlike rock associated with slate, quartzite, etc. after these rocks were raised into land and subjected to weathering the old iron compounds were altered to oxides, mainly hematite, and somewhat concentrated. further concentration of the ore was caused by dissolving out the flintlike layers of the old rocks. the birmingham, ala., region is the second most important iron ore producer in the united states, with an output of nearly , , tons in . the ore is hematite, forming part of the famous clinton iron ore deposits of silurian age. this deposit, named from clinton, n. y., extends through central new york and in more or less interrupted parallel bands through the appalachian mountains to near birmingham where the richest deposits occur. this ore appears to be an original bed (or locally several beds) of fairly rich iron ore deposited on the shallow silurian sea bottom and then covered by other strata. at the time of the appalachian mountain revolution the iron ore was more or less highly folded in with other strata throughout the appalachians. a remarkable fact regarding the birmingham district is that in the near vicinity of the ore there are both coal for fuel and limestone flux for smelting the ores. the next most important mining region of the united states is the adirondack mountain region of northern new york, where about , , tons of ore are obtained yearly. magnetite is the ore, and it occurs in more or less irregular lenses and bands in granite and closely associated rocks of pre-paleozoic age. one view regarding the origin of this ore is that it segregated during the process of cooling of the molten granite, and another view (recently advocated by the author) is that it was derived from an older iron-rich igneous formation by either the molten granite or very hot solutions from it and concentrated into the ores. about , , tons of magnetite were mined in the united states in , nearly one-half of it in the adirondacks. the third important iron ore is limonite, nearly , , tons of which were produced in the united states in . most of it came from the appalachian mountains. all of this limonite is of secondary origin; that is, it has been derived from certain early paleozoic iron-bearing limestones either by weathering or solution, and concentrated into ore deposits. copper. this is one of the most useful of all metals. several of its very important uses are as a conductor of electricity in the form of wire; in making alloys such as brass and bronze; in copperplate engraving; and in roofing and plumbing. various minerals containing copper are found in many parts of the world, but only about six of them are really important as ores. these are native copper, chalcopyrite, chalcocite, azurite, malachite, and cuprite, most of which are described in the chapter on "mineralogy." the number of places where they may be profitably mined as ore is distinctly limited. fifteen or twenty countries produce more or less copper, but the united states is by far the greatest producer, with an output of nearly , , , pounds of copper in , the output having fallen off some in . this was two-thirds of the world's output and ten times as much as the nearest competitor. the other leading countries are japan, chile, mexico, spain, and canada. in the four leading states in order were arizona, montana, michigan, and utah, with production ranging from nearly , , pounds to about , , pounds. in arizona several great copper-mining districts lie in the southeastern one-fourth of the state. almost invariably the ores are directly associated with limestone and an igneous rock (granite), both of late paleozoic age. the ores are almost always near the border between the two rocks, mostly as great irregular deposits within the limestone, and less commonly as veins within the granite. the original ores were carried in solution and deposited by hot liquids (or vapors) from the cooling granite. at lower levels the ores are mainly sulphides of copper (e.g., chalcopyrite and chalcocite), while at higher levels they are mostly carbonates (malachite and azurite) and oxides (e.g. cuprite). the difference is due to the fact that the ores nearer the surface have been subjected to weathering and altered from their original condition. the region around butte, mont., is next to the greatest copper producer. nearly all the ores are sulphides of copper (mainly chalcocite) which occur with quartz in a great system of nearly parallel veins in granite of tertiary age. "it is supposed that in the copper veins the hot ore-bearing solutions ascended the fractures in the granite, replacing the rock by ore, and resulting in an intense alteration of the walls." (ries.) third in rank among the copper-producing states is michigan, the mines being located on keweenaw peninsula, which extends into lake superior. for fully fifty years this district has been one of the most famous and important copper producers in the world. a unique feature is that the ore is native copper, associated with some native silver. the rocks containing the ore are steeply tilted lava sheets and conglomerate (cemented gravel) strata of proterozoic age. openings in porous lava and spaces between the conglomerate pebbles have been filled by metallic copper, which was carried off in hot solutions from the cooling lavas. certain of the mining shafts have been sunk more than , feet below the surface, these being next to the deepest in the world. utah ranks fourth among the copper producers, the greatest mining district being at bingham canyon, southwest of salt lake city. the rocks are late paleozoic strata, pierced by a large body of igneous rock. some of the sulphide ores (mainly chalcopyrite) occur in veins in the igneous rock and some in large tabular masses in the adjacent limestone. hot solutions from lower portions of the uncooled igneous rock carried the ore in solution into the limestone and into cracks in the upper cooled igneous rock. lead. lead must surely be counted among the five or six most useful metals. as in the case of nearly all the other most important natural resources, the united states is the world's greatest producer of lead, the output of metallic lead having been , tons in and somewhat less in . most of this came from missouri, idaho, utah, and colorado. the leading other countries are in order--spain, germany, mexico, and australia. nearly all the lead comes from the mineral galena (a sulphide of lead), which is described in the chapter on "mineralogy." among the many uses of lead are the following: manufacture of certain high-grade paints from lead compounds; making alloys such as pewter, type metal, solder, babbit metal; in plumbing; in glass making; and in the manufacture of shot. the greatest lead-mining district is in the vicinity of joplin, mo., where the ore (galena), associated with much zinc ore, occurs as veins and great irregular deposits in limestone of early paleozoic age. it is generally agreed that underground waters dissolved the ores out of the limestone in which they were disseminated as tiny particles and deposited them in concentrated form at lower levels. in the famous coeur d'alene district of northern idaho the great output of lead is really obtained from a lead-silver ore; that is, galena rich in silver. this ore is in composition a lead-silver sulphide. it occurs in great fissure veins, mostly following fault fractures in highly folded strata of proterozoic age. igneous rocks cut through the strata, and it is believed that hot ore-bearing solutions given off from the highly heated igneous rocks rose in the fissures and deposited the ores. the park city and tintic districts of utah are great producers of lead. the lead ore (galena) is usually rich in silver. it occurs mainly in veins and irregular deposits in limestone of paleozoic age closely associated with certain igneous rocks. one of the most famous mining districts in the world is that around leadville, col., where ores of four metals--gold, silver, lead, and zinc--have been extensively mined. the salient points in the rather complex geology are the following: paleozoic strata, including much limestone, rest upon a foundation of pre-paleozoic granite. sheets of igneous rock are interbedded with the strata and many dikes of igneous rocks cut through the whole combination. after the last igneous activity all the rocks were somewhat folded and notably faulted in many places. the ores were dissolved out of the igneous rock and deposited in large masses mostly in the limestone and in fissure veins, especially along and near the fault zones. zinc. another of the few most useful metals is zinc. it never occurs in metallic form in nature, but most of it by far is obtained from the ore mineral sphalerite (sulphide of zinc) described in the chapter on "mineralogy." a red oxide of zinc ore, called zincite, assumes great economic importance in new jersey. in the united states produced , tons of metallic zinc and was easily the world's leader. since the production has fallen notably. the four greatest producing states are missouri, montana, new jersey, and colorado. germany and belgium are the greatest foreign producers. most important of all in the united states is the district around joplin, mo., where the ore is closely associated with lead ore. the mode of occurrence and origin of these ores are above referred to in the discussion of lead. in montana some of the great east-west fissure veins in granite are rich in silver ores in the upper levels, and in zinc ores (mainly sphalerite) at depths of from some hundreds of feet to nearly , feet, that is as far down as they have been mined. they, like the great copper veins of the same general district, were carried by hot solutions which rose from the lower still very hot granite and deposited the ores in fissures of the same cooler rock higher up. two great ore bodies in the general vicinity of franklin, n. j., are of unique interest, because they are mostly the red oxide of zinc called zincite. the ore deposits occur in white limestone along or close to its contact with metamorphosed (altered) strata and granite of early paleozoic age. it is not definitely known how the ore originated, but it was probably derived in solution from the hot granite and deposited in the limestone by replacement of the latter. in colorado the principal zinc mines are around leadville, where lead ore is nearly always directly associated with the zinc ore. this district is above described in the discussion of lead. among many uses of zinc are for galvanizing; for making certain high-grade paints; brass and white metal; and for roofing and plumbing. gold. this precious metal has been used and highly prized by man for thousands of years. the discovery of gold in california in was one of the most important events in the history of the mining world. as early as that state reached its climax of production with an output of at least $ , , worth of the metal. the transvaal region of south africa has for two decades been the world's greatest gold producer. though long known, the metal has there been worked only since . in the peak of gold production in the world ($ , , ) was reached and nearly maintained in , but since that time there has been a great falling off. in south africa produced gold to the value of about $ , , ; the united states over $ , , ; australia over $ , , ; russia over $ , , ; and canada over $ , , . in tiny amounts gold is really very widespread. it occurs in many stream gravels where so-called "color" may be obtained by washing gravel, and it is even dissolved in sea water. gold-mining localities are also numerous in many parts of the world, but relatively few of them only have ever paid. the total amount of money spent in actual gold-mining operations; in hopeless but honest operations; and for stock in fake gold mines has no doubt exceeded the actual value of gold produced. in many a case acceptance of a report based upon a very brief examination of the ground by a competent geologist would have saved the cost of hopeless expenditure of money. some one in nearly every community has a so-called "gold mine." most of the commercially valuable gold occurs in nature as native gold, either mixed with gravel and sand (i.e., placer deposits) along existing or ancient stream beds, or in veins mechanically held in the mineral pyrite (described in the preceding chapter) in submicroscopic form, or visibly mixed with quartz in vein deposits. another kind of ore which assumes considerable importance, as in parts of colorado, is in the form of telluride of gold always found in veins. in deep vein deposits it is quite the rule to find free or native gold mechanically and visibly mixed with quartz in the upper levels, while deeper down the gold is mechanically, but invisibly, held in combination usually in pyrite, which latter is associated with quartz. this difference is due to the fact that the lower level ores are now just as they were formed, while in the upper levels the ores have been weathered, and the gold set free and often more or less further concentrated by solutions. vein deposits, including also telluride ores, are found in many kinds of rocks--igneous, sedimentary, and metamorphic--of nearly all ages generally directly associated with igneous rocks. in nearly all cases the best evidence indicates that the vein fillings were formed by hot ore-bearing solutions from the igneous rock, which solutions deposited the ore plus quartz in fissures in either the igneous or adjacent rocks. among the many localities where fissure veins of the kind just described are of great economic importance are the "mother lode" belt of the sierra nevada mountains of california; cripple creek (telluride ore), georgetown and the san juan region of colorado; goldfield, tonopah, and comstock lode of nevada; and near juneau, alaska. placer deposits, that is, free gold mixed with gravel and sand, also yield much gold. they are most prominently developed in california and alaska. these gold-bearing "gravels represent the more resistant products of weathering, such as quartz and native gold, which have been washed down from the hills on whose slopes the gold-bearing quartz veins outcrop, and were too heavy to be carried any distance, unless the grade was steep. they have consequently settled down in the stream channels, the gold, on account of its higher specific gravity, collecting usually in the lower part of the gravel (placer) deposit." (ries.) such gold occurs as grains, flakes, or nuggets. when a chunk of gold-bearing vein quartz, with crevices filled by thin plates of the metal, is carried downstream pieces are gradually broken away, and the tough, very malleable gold bends or welds together into a single mass called a "nugget." nuggets varying in weight up to over , ounces have been found. many placer deposits are along existing drainage channels, while others occur in abandoned and even buried former channels. most of the gold of south africa comes from witwatersrand district where the native metal occurs in a unique manner in beds or layers of conglomerate associated with other strata, all the rocks being considerably folded and somewhat faulted. some of the mines are more than a mile deep (vertically), the deepest in the world. the gold either accumulated in placer form with gravel which later consolidated into conglomerate, or it was introduced into spaces between the pebbles subsequently by ore-bearing solutions. silver. for many years the united states and mexico have been the world's greatest silver producers, sometimes one and sometimes the other leading, with canada third, and australasia fourth. in the united states produced nearly , , ounces of silver and mexico over , , ounces. in the united states in the four leading states were montana, utah, idaho and nevada with outputs ranging from over , , to over , , ounces each. in montana most of the silver is in the native form, more especially in the upper portions of the great veins rich in copper and zinc ores near butte. these ores and their origin are described above under the captions "copper" and "zinc." the two greatest silver districts of nevada are tonopah and comstock lode where silver and gold minerals are associated as ores in tertiary igneous rocks, the ores having been deposited in veins by hot ore-bearing solutions from the igneous rocks. in idaho the coeur d'alene district produces most of the silver, the ore there being a silver-bearing lead ore (galena). the nature and origin of these deposits are described above under the caption "lead." in utah the silver is also obtained from silver-bearing galena especially in the tintic, cottonwood canyon, and bingham canyon districts where the ores occur mainly as irregular deposits and in fissure veins in paleozoic strata (chiefly limestone) directly associated with igneous rocks, hot ore-bearing solutions from the igneous rocks having furnished the ores. tin. production of tin in the united states has never amounted to much, a little mining having been carried on from time to time in south carolina, black hills of south dakota, and southern california. about one-half of the world's supply of tin ( , long tons ) comes from the malay peninsula and two small islands near by. the only other great producer is bolivia, though a number of other countries produce from , to , tons each. the only important ore of tin is the mineral cassiterite (oxide of tin) described above in the chapter on "mineralogy." in the malay region the ore all occurs in placer deposits and is, therefore, of secondary origin, the source of the ore not being known. in bolivia the tin ore occurs in veins in and close to granite, the ore having been carried by very hot vapors or liquids which were derived from the still highly heated granite. tin is used chiefly in the making of tin plate, bronze, pewter, gun metal, and bell metal. aluminum. the mineral called bauxite (a hydrous oxide of aluminum) is the great ore from which aluminum is obtained by an electrical process. bauxite is noncrystalline, relatively light in weight, white to yellowish in color, and in the form of rounded grains, or earthy or claylike masses. the united states and france are the only two great producers of bauxite, most of which is treated for metallic aluminum. in the united states produced more than , tons of aluminum. in the united states the principal deposits are in georgia, alabama, and arkansas. bauxite is probably always a secondary mineral formed by decomposition of igneous rocks rich in certain aluminum silicate minerals. in some cases, as in the georgia-alabama region, the bauxite appears to have been formed and concentrated in deposits by hot solutions from uncooled igneous rocks. aluminum is most used in the manufacture of wire for electric current transmission. it is also mixed with certain other metals like copper, zinc, magnesium, and tungsten to form special types of alloys, some of which possess remarkable tensile strength up to nearly , pounds per square inch. aluminum is used in powdered form to generate very high temperatures in certain welding processes. it is also made into many kinds of utensils and instruments. mercury. this metal, commonly known as "quicksilver," is of special interest because it is the only one which exists in liquid form at ordinary temperatures. the metal occurs in only small quantities in nature, most of it by far being obtained from the red mineral cinnabar described in the chapter on "mineralogy." in order of importance the greatest quicksilver producing countries in were italy, united states, austria, and spain. in the united states, california is by far the leading state, while texas and nevada are the only other important producers. in california most of the ore occurs in veins and irregular deposits in metamorphosed strata of mesozoic and cenozoic ages usually closely associated with igneous rocks. there, as well as in other parts of the world, hot vapors from igneous rocks carried the volatile ore upward and deposited it in fissures. among the many uses of mercury are in making fulminate for explosives; making certain drugs and chemicals, pigments, electrical and physical apparatus; silvering mirrors; and in the amalgamation process of extracting gold and silver. other economic products building stones. some of the principal features which should be considered in building stones are power to resist weathering, power to withstand heat, color, hardness, and density, and crushing strength. building stones representing rocks of nearly all important geologic ages are widely distributed throughout the world. _granite_, including certain other closely related rocks, is one of the oldest and most useful building stones. the new england states are the greatest producers, while the piedmont plateau district (east of the appalachians) from philadelphia to alabama also contains important granite quarries. in the adirondack mountains, in wisconsin and minnesota, through the rocky mountains, and the sierra nevada mountains there are extensive areas of granite which are relatively little quarried. the granite occurs only in regions of highly disturbed rocks, usually in mountains or hills, where great volumes of the molten rock were forced into the earth's crust, cooled, and later laid bare by erosion. _marble_, according to geological definition, is a metamorphosed limestone, that is a limestone which has been crystallized under conditions of heat, pressure, and moisture within the earth. more loosely in trade any limestone which takes a polish may be called marble. the greatest marble-producing districts of the united states are western new england (especially vermont) and the piedmont plateau and appalachian mountains in rocks of paleozoic age. in northern new york and the mountains of the west there are relatively few marble quarries. ordinary _limestones_ are widely distributed in many states where they range in age from early paleozoic to tertiary. most of the quarries supply stone for near-by markets. the so-called bedford limestone of indiana has, for many years, been perhaps the most widely used limestone for building purposes in the united states. _sandstones_, which are stratified rocks consisting mainly of rounded quartz grains cemented together, are widely used in building operations. like limestones, they are very widespread in formations of all ages except the very old. there are many sandstone quarries supplying more or less local markets throughout the country. two of the best known and most widely used sandstones are the so-called brown-stone of triassic age extending interruptedly from the connecticut valley of massachusetts to north carolina, and the berea, ohio, sandstone of light gray color and uniform texture. _slate_ is mostly a metamorphosed shale, that is a shale which has been subjected to great pressure within the earth so that the stratification has been obliterated and a well defined cleavage has been developed at right angles to the direction of application of the pressure. good slate is fine-grained, dense, and splits readily into wide thin plates. it occurs only where mountain making pressure and metamorphism have been brought to bear upon the strata. most of our great slate quarries are located in early paleozoic rocks from new england through the piedmont plateau. some quarries are also located in arkansas, minnesota, and westward to california. clay. "clay, which is one of the most widely distributed materials and one of the most valuable, commercially, may be defined as a fine-grained mixture of the mineral kaolinite with fragments of other minerals, such as silicates, oxides, and hydrates, and also often organic compounds, the mass possessing plasticity when wet and becoming rock-hard when burned to at least a temperature of redness." (ries.) most clays originate by the weathering of rocks, particularly igneous and metamorphic rocks rich in the mineral feldspar. as a result of the decomposition of the feldspar, much clay is formed, the main substance of which is kaolin. both feldspar and kaolin are described in the preceding chapter. when the resulting clay rests upon the rock from which it has been derived it is called residual clay. much of the clay is, however, carried away, mainly by streams, and deposited in lakes or the sea, or on river flood plains. some clay deposits are of wind-blown origin, and still others are formed by the grinding action of glaciers. clays are very widespread, and they are directly associated with rocks of all geologic ages. among the many important uses of clay are the following: manufacture of common brick, fire brick, pottery, chinaware, porcelain ware, tiles, terra cotta, and portland cement. lime and cement. limestone, which is one of the most common and widespread of all stratified rocks, forms the basis for the manufacture of the important substances lime (or "quicklime") and portland cement. lime results when pure limestone (carbonate of lime) is "burned" or heated to a temperature high enough to drive off the carbonic acid gas. the greatest use of lime is for mixing with water and sand to make mortar. a few of its other numerous uses are in plastering; whitewashing; purifying certain steel; in making gas, paper, and soap; and as a fertilizer. certain limestones containing clay of the right kind and proportion are called natural cement rocks because, after being "burned," they develop the property of "setting," like cement when mixed with water. the "setting" of a cement is due to the fact that certain chemical compounds formed during the heating crystallize when mixed with water, and the hard, tiny interlocking crystals of the newly formed silicate minerals give rigidity to the mass. of recent years portland cement has largely superseded the natural rock cements. "portland cement is the product obtained by burning a finely ground artificial mixture consisting essentially of lime, silica, alumina, and some iron oxide, these substances being present in certain definite proportions." (ries.) the necessary ingredients are generally obtained by grinding and burning carefully selected mixtures of limestone in some form, and clay or shale. the great and growing uses of cement need not be detailed here. salt. most of the common salt (the mineral "halite") of commercial value occurs in nature in sea or salt lake water; or in beds or strata of rock salt associated with other strata; or as natural brine in openings or pores in certain rocks. considerable salt is obtained by evaporation of tidewater, as around san francisco bay, and of salt lake water, as at great salt lake, utah. it has been estimated that the great salt lake, whose area is about , square miles and greatest depth feet, contains several hundred million tons of common salt. this salt has been washed out of the rocks of the surrounding country and gradually accumulated in the lake because it has no outlet. most important of all sources of salt is the rock salt which occurs in the form of strata within the earth's crust. such strata are found in rocks of nearly all ages from the early paleozoic to the present. they resulted from the evaporation of salt lakes or salty more or less cut-off arms of the sea, after which other strata accumulated on top of them. thus in the silurian system of strata underlying all of southwestern new york state there occur almost universally from one to seven beds of salt. the strata including the salt dip gently southward so that at ithaca, new york, seven salt beds were struck in a well at a depth of about , feet. northward the salt comes nearer and nearer the surface. one well penetrated a layer of solid salt feet thick. some of this salt is being mined much like coal, but most of it is obtained by running water into deep wells to dissolve the salt, the resulting brine being pumped out and evaporated. under portions of southern michigan there are both salt beds and natural brines charging certain porous rock layers. both the salt beds (of silurian age) and the brines (of mississippian age) supply great quantities of salt from brines pumped out and evaporated. in the united states produced , , barrels ( lbs. each) of salt. michigan ( , , barrels) and new york were the leading states, followed by kansas, ohio, west virginia, and california. some of the uses of common salt are given in the description of halite in the preceding chapter. gypsum. the composition and properties of this common and useful mineral are given in the chapter on "mineralogy." rock gypsum is the variety of great commercial importance. it is widespread, being quarried in many states, and occurs interstratified with rocks of many ages where it has originated by evaporation or partial evaporation of salt water lakes or more or less cut-off arms of the sea. salt beds are often associated with gypsum. for about ten years the average yearly production of gypsum in the united states has been approximately , , tons, or about ten times that of the nearest foreign competitor (canada). new york, iowa, michigan, and ohio are the chief producers. in new york the rock gypsum (usually four to ten feet thick) lies between shale and limestone strata of silurian age, and it is quarried from the central to the western part of the state. in michigan the rock gypsum beds, commonly five to twenty feet thick, lie in mississippian strata in the southern portion of the state. a great bed of exceptionally pure rock gypsum underlies about twenty-five square miles of webster county, iowa, in rocks of late paleozoic age. the kansas gypsum deposits extend across the central part of the state in rocks of permian age. rock gypsum is mainly used in making "plaster of paris," as a retarder in cement, and as a fertilizer (so-called "land plaster"). glossary of common geological terms names of subkingdoms and important classes of fossil plants and animals, and mineral species, are not included; these being briefly and systematically discussed in chapters , , , and , respectively. by using the index the reader can quickly locate the page where any one of these names is discussed. some definitions in this glossary are taken from u. s. survey bulletin no. . _anticline._--a kind of folded structure in which strata have been bent upward or arched. _archeozoic._--the earliest known era of geologic time. _basalt._--a common lava of dark color and of great fluidity when molten. basalt is less siliceous than granite and rhyolite, and contains much more iron, calcium, and magnesium. _base-level._--the lowest level to which a stream can cut (erode) its channel. a whole region may be base-leveled by erosion. _cambrian._--the first or earliest period of the paleozoic era of geologic time. _cenozoic._--the present era of geologic time. it began at least several million years ago. _chalk._--a soft, fine-grained, white limestone consisting mainly of tiny shells. _conglomerate._--a sedimentary rock consisting of consolidated or cemented gravel. often sandy. _cretaceous._--the last period of the mesozoic era of geologic time. _crystal._--a regular polyhedral form, possessing a definite internal molecular structure, which is assumed by a substance in passing from the state of a liquid or gas to that of a solid. nearly every mineral, under proper conditions, will crystallize. _crystalline rock._--a rock composed of closely fitting mineral crystals that have formed in the rock substance, as contrasted with one made up of cemented grains of sand or other materials, or with a volcanic glass. _crystallography._--the study of crystals. _devonian._--the middle one of the seven periods of the paleozoic era of geologic time. _dike._--a mass of igneous rock that has solidified in a fissure or crack in the earth's crust. _drift._--commonly called glacial drift. the rock fragments--soil, gravel, and silt--carried by a glacier. drift includes the unassorted material known as till (ground moraine) and deposits made by streams flowing from a glacier. _drowned river valley._--when a land surface sinks enough to permit tidewater to enter the lower ends of its valleys to form estuaries, a good example being the lower hudson valley. _era._--a name applied to one of the broadest subdivisions of geologic time (e.g. paleozoic era). _erosion._--the wearing away and transportation of materials at and near the earth's surface by weathering and solution, and the mechanical action of running water, waves, moving ice, or winds which use rock fragments as tools or abrasives. _exfoliation._--the splitting off of sheets of rock of various sizes and shapes due to changes of temperature. it is a process of weathering. _fault._--a fracture in the earth's crust accompanied by movement of the rock on one side of the break past that on the other. if the fracture is inclined and the rock on one side appears to have slid down the slope of the fracture the fault is termed a normal fault. if, on the other hand, the rock on one side appears to have been shoved up the inclined plane of the break, the fault is termed a reverse or thrust fault. _fault-block._--a part of the earth's crust bounded wholly or in part by faults. _fault-scarp._--the cliff formed by a fault. most fault scarps have been modified by erosion since the faulting. _fissure._--a crack, break, or fracture in the earth's crust or in a mass of rock. _flood-plain._--the nearly level land that borders a stream and is subject to occasional overflow. flood-plains are built up by sediment left by such overflows. _fold._--a bend in rock layers or beds. anticlines and synclines are the common types of folds. _formation._--a rock layer, or a series of continuously deposited layers grouped together, regarded by the geologist as a unit for purposes of description and mapping. a formation is usually named from some place where it is exposed in its typical character. _fossil._--the whole or any part of an animal or plant that has been preserved in the rocks or the impression left on rock by a plant or animal. preservation is invariably accompanied by some change in substance, and from some fossils the original substance has all been removed. _geography._--the study of the distribution of the earth's physical features, in their relation to each other to the life of sea and land, and human life and culture. _geology._--the science which deals with the history of the earth and its inhabitants as revealed in the rocks. _glacier._--a body of ice which slowly spreads or moves over the land from its place of accumulation. _gneiss_ (pronounced nice).--a metamorphic, crystalline rock with mineral grains arranged with long axes more or less parallel, giving the rock a banded appearance. derived from either igneous or stratified rocks well within the earth under conditions of pressure, and usually also heat and moisture. _igneous rocks._--rocks formed by the cooling and solidification of a hot liquid material, known as magma, that has originated at unknown depths within the earth. those that have solidified beneath the surface are known as intrusive rocks, or if the cooling has taken place slowly at great depth, as plutonic rocks, e.g. granite. those that have flowed out over the surface are known as effusive rocks, extrusive rocks, or lavas, e.g., basalt. volcanic rocks include not only lavas, but bombs, pumice, tuff, volcanic ash, and other fragmental materials or ejecta thrown out from volcanoes. _joints._--nearly all rocks, except very loose surface materials, are separated into blocks of varying size and shape by a system of cracks called joints. they may be caused by earth-crust movements, contraction during solidification of molten rocks, or contraction during drying out of sediments. _jurassic._--the middle one of the three periods of the mesozoic era of geologic time. _lava._--an igneous rock which in molten condition has poured out upon or close to the earth's surface, e.g. basalt. _limestone._--a sedimentary rock consisting essentially of carbonate of lime which generally represents accumulation of shells of organisms, but in some cases precipitates from solution. often impure. _loess_ (pronounced lurse with the r obscure).--a fine homogeneous silt or loam showing usually no division into layers and forming thick and extensive deposits in the mississippi valley and in china. it is generally regarded as in part at least a deposit of wind-blown dust. _marble._--a crystalline limestone, usually a metamorphic rock, the limestone having been altered by heat, pressure, and moisture within the earth. _meander._--to flow in serpentine curves. a loop in a stream. most streams in flowing across plains develop meanders. _mesa._--a flat-topped hill or mountain left isolated during the general erosion or cutting down of a region. _mesozoic._--next to the present era of geologic time. _ metamorphic rock._--any igneous or sedimentary rock which has undergone metamorphism, that is notable alteration from its original condition. (see metamorphism.) _metamorphism._--any change in rocks effected in the earth by heat, pressure, solutions, or gases. a common cause of the metamorphism of rocks is the intrusion into them of igneous rocks. rocks that have been so changed are termed metamorphic. marble, for example, is metamorphosed limestone. _mineral._--an inorganic substance of definite chemical composition found ready made in nature, e.g. calcite, quartz. _mississippian._--a period of the paleozoic era of geologic time--in order of age, the third from the last of the era. _moraine._--glacial drift carried on, within, or under a glacier and deposited at the end, along the sides, or under the glacier. _oil-pool._--an accumulation or body of oil in sedimentary rock that yields petroleum on drilling. the oil occurs in the pores of the rock and is not a pool or pond in the ordinary sense of these words. _ordovician._--next to the earliest period of the paleozoic era of geologic time. _ore._--a metal-bearing mineral or rock of sufficient value to be mined. _outcrop._--that part of a rock formation which appears at the surface. the appearance of a rock at the surface or its projection above the soil. often called an exposure. _paleontology._--the study of the world's (geologically) ancient life, either plant or animal, by means of fossils. _paleozoic._--an old era of geologic time--third back from the present. _peneplain._--a region reduced almost to a plain by the long-continued normal erosion of a land surface. it should be distinguished from a plain produced by the attack of waves along a coast or the built-up flood plain of a river. _pennsylvanian._--next to the last period of the paleozoic era of geologic time. _period._--a name applied to one of the subdivisions of an era of geologic time, e.g. cambrian period. _permian._--the last period of the paleozoic era of geologic time. _petrology._--the study of rocks, including igneous, sedimentary, and metamorphic rocks. _physiography._--the study of the relief features of the earth and how they were produced. _placer deposit._--a mass of gravel, sand, or similar material resulting from the crumbling and erosion of solid rocks and containing particles or nuggets of gold, platinum, tin, or other valuable minerals, which have been derived from rocks or veins. _plutonic rock._--an igneous rock solidified from a molten condition well within the earth. (see igneous rocks.) _proterozoic._--next to the earliest known era of geologic time. _quartzite._--a metamorphic rock composed of sand grains cemented by silica into an extremely hard mass. _quaternary._--the later of the two periods of the cenozoic era of geologic time. _rejuvenated._--any region which has been subjected to erosion for a greater or less length of time and then reelevated so that the streams are renewed in activity. _rock._--any extensive constituent of the crust of the earth, usually consisting of a mechanical mixture of two or more minerals, e.g. granite, shale. less commonly a rock consists of a single mineral (e.g. pure marble), or of organic matter (e.g. coal). _sandstone._--a sedimentary rock consisting of consolidated or cemented sand. often shaly or limy. _schist._--a rock that by subjection to heat and pressure and usually moisture within the earth has undergone a change in the character of the particles or minerals that compose it and has these minerals arranged in such a way that the rock splits more easily in certain directions than in others. it is a metamorphic rock derived from either sedimentary or igneous rock, more commonly the former. _sedimentary rocks._--rocks formed by the accumulation of sediment in water (aqueous deposits) or from air (eolian deposits). the sediment may consist of rock fragments or particles of various sizes (conglomerate, sandstone, shale); of the remains or products of animals or plants (certain limestones and coal); of the product of chemical action or of evaporation (salt, gypsum, etc.); or of mixtures of these materials. some sedimentary deposits (tuffs) are composed of fragments blown from volcanoes and deposited on land or in water. a characteristic feature of sedimentary deposits is a layered structure known as bedding or stratification. each layer is a bed or stratum. sedimentary beds as deposited lie flat or nearly flat, but subsequently they have often been deformed by folding and faulting. _shale._--a sedimentary rock consisting of hardened thin layers of fine mud. _silurian._--a period of the paleozoic era of geologic time--in order of age, the third from the beginning of the era. _slate._--a rock that by subjection to pressure within the earth has acquired the property of splitting smoothly into thin plates. the cleavage is smoother and more regular than the splitting of schist along its grain. it is a metamorphic rock nearly always derived from shale. _soil._--the mantle of loose material resting upon bedrock, either in its place of origin or transported by water, wind, or ice. _strata_ (or stratified rocks).--sedimentary rocks which, by the sorting power of water (less often by wind), are arranged in more or less definite layers or beds separated by stratification surfaces. _stratification._--the separation of sedimentary rocks into more or less parallel layers or beds. _stratigraphy._--the branch of geologic science that deals with the order and relations of the strata of the earth's crust. _structure._--in geology, the forms assumed by sedimentary beds and igneous rocks that have been moved from their original position by forces within the earth, or the forms taken by intrusive masses of igneous rock in connection with effects produced mechanically on neighboring rocks by the intrusion. folds (anticlines and synclines) and faults are the principal mechanical effects considered under structure. schistosity and cleavage are also structural features. _syncline._--a kind of folded structure in which strata have been bent downward. it is an inverted arch--the opposite of an anticline. _talus_ (pronounced t[=a]y'lus).--the mass of loose rock fragments that accumulates at the base of a cliff or steep slope. _terrace._--a steplike bench on a hillside. most terraces along rivers are remnants of valley bottoms formed when the stream flowed at higher levels. other terraces have been formed by waves. some terraces have been cut in solid rock, others have been built up of sand and gravel, and still others have been partly cut and partly built up. _tertiary._--the earlier of the two periods of the cenozoic era of geologic time. _triassic._--the earliest period of the mesozoic era of geologic time. _unconformity._--a break in the regular succession of sedimentary rocks, indicated by the fact that one bed rests on the eroded surface of one or more beds which may have a distinctly different dip from the bed above. an unconformity may indicate that the beds below it have at some time been raised above the sea and have been eroded. in some places beds thousands of feet thick have been washed away before the land again became submerged and the first bed above the surface of unconformity was deposited. if beds of rock may be regarded as leaves in the volume of geologic history, an unconformity marks a gap in the record. _vein._--a mass of mineral material that has been deposited in or along a fissure in the rocks. a vein differs from a dike in that the vein material was introduced gradually by deposition from solution, whereas a dike was intruded in a molten condition. quartz and calcite are very common vein minerals. _volcanic rocks._--igneous rocks erupted at or near the earth's surface, including lavas, tuffs, volcanic ashes, and like material. _weathering._--the group of processes, such as the chemical action of air and rain water, and of plants and bacteria, and the mechanical action of changes of temperature, whereby rocks on exposure to the weather change in character, decay, and finally crumble into soil. transcriber note all illustrations splitting paragraphs were moved before or after the paragraph. all simple typos were corrected (i.e., reudemann to ruedemann, pryoxene to pyroxene). [illustration: the mer de glace showing the cleft station at trélaporte, les echelets, the tacul, the périades and the grande jorasse.] the glaciers of the alps. being a narrative of excursions and ascents, an account of the origin and phenomena of glaciers, and an exposition of the physical principles to which they are related. by john tyndall, f.r.s. with illustrations. _new edition._ longmans, green, and co. london, new york, and bombay. . _all rights reserved_ to michael faraday, this book is affectionately inscribed. . preface. in the following work i have not attempted to mix narrative and science, believing that the mind once interested in the one, cannot with satisfaction pass abruptly to the other. the book is therefore divided into two parts: the first chiefly narrative, and the second chiefly scientific. in part i. i have sought to convey some notion of the life of an alpine explorer, and of the means by which his knowledge is acquired. in part ii. an attempt is made to classify such knowledge, and to refer the observed phenomena to their physical causes. the second part of the work is written with a desire to interest intelligent persons who may not possess any special scientific culture. for their sakes i have dwelt more fully on principles than i should have done in presence of a purely scientific audience. the brief sketch of the nature of light and heat, with which part ii. is commenced, will not, i trust, prove uninteresting to the reader for whom it is more especially designed. should any obscurity exist as to the meaning of the terms structure, dirt-bands, regelation, interference, and others, which occur in part i., it will entirely disappear in the perusal of part ii. two ascents of mont blanc and two of monte rosa are recorded; but the aspects of nature, and other circumstances which attracted my attention, were so different in the respective cases, that repetition was scarcely possible. the numerous interesting articles on glaciers which have been published during the last eighteen months, and the various lively discussions to which the subject has given birth, have induced me to make myself better acquainted than i had previously been with the historic aspect of the question. in some important cases i have stated, with the utmost possible brevity, the results of my reading, and thus, i trust, contributed to the formation of a just estimate of men whose labours in this field were long anterior to my own. j. t. _royal institution, june, ._ prefatory note. "glaciers of the alps" was published nearly six and thirty years ago, and has been long out of print, its teaching in a condensed form having been embodied in the little book called "forms of water." the two books are, however, distinct in character; each appears to me to supplement the other; and as the older work is still frequently asked for, i have, at the suggestion of my husband's publishers, consented to the present reprint, which may be followed later on by a reprint of "hours of exercise." before reproducing a book written so long ago, i sought to assure myself that it contained nothing touching the views of others which my husband might have wished at the present time to alter or omit. with this object i asked lord kelvin to be good enough to read over for me the pages which deal with the history of the subject and with discussions in which he himself took an active part. in kind response he writes:--"... after carefully going through all the passages relating to those old differences i could not advise the omission of any of them from the reprint. there were, no doubt, some keen differences of opinion and judgement among us, and other friends now gone from us, but i think the statements on controversial points in this beautiful and interesting book of your husband's are all thoroughly courteous and considerate of feelings, and have been felt to be so by those whose views were contested or criticised in them." the current spelling of swiss names has changed considerably since "glaciers of the alps" was written, but, except in the very few cases where an obvious oversight called for correction, the text has been left unaltered. only the index has been made somewhat fuller than it was. l. c. t. _january, ._ contents. part i. page .--introductory. visit to penrhyn; the cleavage of slate rocks; sedgwick's theory--its difficulties; sharpe's observations; sorby's experiments; lecture at the royal institution; glacier lamination; arrangement of an expedition to switzerland .--expedition of : the oberland. valley of lauterbrunnen; pliability of rocks; the wengern alp; the jungfrau and silberhorn; ice avalanches; glaciers formed from them; scene from the little scheideck; the lower grindelwald glacier; the heisse platte--its avalanches; ice minarets and blocks; echoes of the wetterhorn; analogy with the reflection of light from angular mirrors; the reichenbach cascade; handeck fall; the grimsel; the unteraar glacier; hut of m. dollfuss; hôtel des neufchâtelois; the rhone glacier from the mayenwand; expedition up the glacier; coloured rings round the sun; crevasses of the _névé_; extraordinary meteorological phenomenon; spirit of the brocken .--the tyrol. kaunserthal and the gebatsch alp; senner or cheesemakers; gebatsch glacier; a night in a cowshed; passage to lantaufer; a chamois on the rocks; my guide; the atmospheric snow-line; passage of the stelvio; colour of fresh snow; bormio; the pass recrossed by night; aspect of the mountains; meran to unserfrau; passage of the hochjoch to fend; singular hailstorm; wild glacier region; hidden crevasses; first paper presented to the royal society .--expedition of : the lake of geneva. blueness of the water; the head of the lake; appearance of the rhone; subsidence of particles; mirage .--chamouni and the montanvert. arrival; coloured shadows on the snow; source of the arveiron; fall of the vault; "sunrise in the valley of chamouni;" scratched rocks; quarters at the montanvert .--the mer de glace. not a _sea_ but a _river_ of ice; wave-forms on its surface; their explanation; structure and strata; glacier tables; first view of the dirt bands; influence of illumination in rendering them visible; the eye incapable of detecting differences between intense lights . measurements commenced; the "cleft station" at trélaporte; regelation of snow granules; two chamois; view of the mer de glace and its tributaries; _séracs_ of the col du géant; sliding and viscous theories; rending of the ice; striæ on its surface; white ice-seams . alone upon the glacier; lakes and rivulets; parallel between glacier and geological disturbance; splendid rainbow; aspect of the glacier at the base of the séracs; visit to the chief guide at chamouni; liberties granted .--the jardin. glacier du talèfre; jardin divides the névé; blue veins near the summit; surrounding scene; moraines and avalanches; cascade du talèfre; dangers on approaching it from above . lightning and rain; spherical hailstones; an evening among the crevasses; dangerous leap; ice-practice; preparations for an ascent of mont blanc .--first ascent of mont blanc ( ). across the mountain to the glacier des bossons; its crevasses; ladder left behind; consequent difficulties; the grands mulets; twinkling and change of colour of the stars; moonlight on the mountains; start with one guide; difficulties among the crevasses; the petit plateau; séracs of the dôme du goûter; bad condition of snow; the grand plateau; coloured spectra round the sun; the lost guides; the route missed; dangerous ice-slope; guide exhausted; cutting steps; cheerless prospect; the corridor; the mur de la côte; the petits mulets; food and drink disappear; physiological experiences on the calotte; summit attained; the clouds and mountains; experiment on sound; colour of the snow; the descent; a solitary prisoner; second night at the grands mulets; inflammation of eyes; a blind man among the crevasses; descent to chamouni; thunder on mont blanc . life at the montanvert; glacier "blower;" cascade of the talèfre; difficulties in setting out lines; departure from the montanvert; my hosts; prospect from the glacier des bois; edouard simond .--expedition of . origin and aim of the expedition; laminated structure of the ice .--passage of the strahleck. unpromising weather; appearance of the glacier and of the adjacent mountains; transverse protuberances; dirt bands; structure; a slip on a snow slope; the finsteraarhorn; the schreckhorn; extraordinary atmospheric effects; summit of the strahleck; grand amphitheatre; mutations of the clouds; descent of the rocks; a bergschrund; fog in the valley; descent to the grimsel . ancient glaciers in the valley of hasli; rounded, polished, and striated rocks; level of the ancient ice; groovings on the grimsel pass; glacier of the rhone; descent of the rhone valley; the Æggischhorn; cloud iridescences; the aletsch glacier; the märjelen see; icebergs; tributaries of the aletsch; grand glacier-region; crevasses; a chamois deceived .--ascent of the finsteraarhorn. character of my guide; iridescent cloud; evening on the faulberg; the jungfrau and her neighbours; a mountain cave; the jungfrau before dawn; contemplated visit; the grünhorn lücke; magnificent corridor; sunrise; névé of the viesch glacier; halt at the base of the finsteraarhorn; spurs and couloirs of the mountain; pyramidal crest; scene of agassiz's observations; a hard climb; discipline of such an ascent; boiling point; registering thermometer, its fate; daring utterance; descent by glissades; the viesch glacier; hidden crevasses; a brave and competent guide . subsequent days at the Æggischhorn; afloat on the icebergs; bedding and structure; ancient moraines of the aletsch; scratched rocks; passage of the mountains to the end of the glacier; a wild gorge; arrival at zermatt; the riffelberg .--first ascent of monte rosa. the ascent new to myself and my guide; directions; ulrich lauener; ominous clouds; passage of the görner glacier; roches moutonnées; avalanche from the twins; gradual advance of clouds; bridged chasms; scene from a cliff; apparent atmospheric struggle; sound of the snow; dangerous edge; overhanging cornice; staff driven through it; increased obscurity; rocky crest; loss of pocket-book; summit attained; boiling point; fall of snow; exquisite forms of the snow crystals; a shower of frozen blossoms; the descent; mode of attachment; startling avalanche; blue light emitted from the fissures of the fresh snow; stifling heat; return to the riffel . the rothe kumm; pleasant companions; difficult descent; temperatures of rock, air, and grass; singular cavern in the ice; structure and stratification .--the görner grat and the riffelhorn; magnetic phenomena. formation and dissipation of clouds; scene from the görner grat; magnetism of the rocks; the compass and sun at variance; ascent of the riffelhorn; magnetic effects; places of most intense action; scratched and polished rocks; exfoliation of crust produced by the sliding of ancient glaciers; magnetic polarity; consequent points; bearings from the riffelhorn; action on a distant needle . fog on the riffelberg; its dissipation; sunset from the görner grat; cloud-wreaths on the matterhorn; streamers of flame; grand interference phenomenon; investigation of structure; the görnerhorn glacier; western glacier of monte rosa; the schwarze, trifti, and théodule glaciers; welding of the tributaries to parallel strips; temptation .--second ascent of monte rosa ( ). a light scrip; my guide lent; a substitute; a party on the mountain; across the glacier and up the rocks; the guide expostulates; among the crevasses; the guide halts; left alone; beauty of the mountain; splendid effects of diffraction; cheer from the summit; on the kamm; climbers meet; among the rocks; alone on the summit; the axe slips; the prospect; the descent; serious accident; a word on climbing alone . the furgge glacier; thunder and lightning; the weissthor given up; excursion by stalden to saas; herr imseng; the mattmark see and hotel; ascent of a boulder; snow-storm; cold quarters; the monte moro; the allalein glacier; a noble vault; structure and dirt-bands; stormy weather; avalanches at saas; the fée glacier; frozen dust on the mischabelhörner; snow, vapour, and cloud; curious effect on the hearing; "a terrible hole;" singular group; a song from 'the robbers' . need of observations on alpine temperature; balmat's intention; aid from the royal society; difficulties at chamouni in ; the intendant memorialised; his response; the séracs revisited; crevasses and crumples; bad weather; thermometers placed at the jardin; avalanches of the talèfre; wondrous sky .--second ascent of mont blanc ( ). shadows of the aiguilles; silver trees at sunrise; m. necker's letter; birds as sparks and stars against the sky; crevasse bridged; ladder rejected; a hunt for a _pont_; crevasses crossed; magnificent sunset; illuminated clouds; storm on the grands mulets; a comet discovered; start by starlight; the petit plateau a reservoir for avalanches; balmat's warning; the grand plateau at dawn; blue of the ice; balmat in danger; clouds upon the calotte; the summit; wind and snow-dust; balmat frostbitten; halt on the calotte; descent to chamouni; good conduct of porters . hostility of chief guide; procès verbal; the british association; application to the sardinian authorities; president's letter; royal society; testimonial to balmat .--winter expedition to the mer de glace, . first defeat and fresh attempt; geneva to chamouni; deep snow; desolation; slow progress; a horse in the snow; a struggle; chamouni on christmas night; mountains hidden; climb to the montanvert; snow on the pines; débris of avalanches; breaking of snow; atmospheric changes; the mountains concealed and revealed; colour of the snow; the montanvert in winter; footprints in the snow; wonderful frost figures; crystal curtain; the mer de glace in winter; the first night; "a rose of dawn;" crimson banners of the aiguilles; the stakes fixed; a hurricane on the glacier; the second night; wild snow-storm; a man in a crevasse; calm; magnificent snow crystals; sound through the falling snow; swift descent; source of the arveiron; crystal cave; appearance of water; westward from the vault; majestic scene; farewell part ii. .--light and heat. what is light?--notion of the ancients; requires time to pass through space; römer, bradley, fizeau; emission theory supported by newton, opposed by huyghens; the wave theory established by young and fresnel; theory explained; nature of sound; of music; of pitch; nature of light; of colour; two sounds may produce silence; two rays of light may produce darkness; two rays of heat may produce cold; length and number of waves of light; liquid waves; interference; diffraction; colours of thin plates; applications of the foregoing to cloud iridescences, luminous trees, twinkling of stars, the spirit of the brocken, &c. .--radiant heat. the sun emits a multitude of non-luminous rays; rays of heat differ from rays of light as one colour differs from another; the same ray may produce the sensations of light and heat .--qualities of heat. heat a kind of motion; system of exchanges; luminous and obscure heat; absorption by gases; gases may be transparent to light, but opaque to heat; heat selected from luminous sources; the atmosphere acts the part of a ratchet-wheel; possible heat of a distant planet; causes of cold in the upper strata of the earth's atmosphere .--origin of glaciers. application of principles; the snow-line; its meaning; waters piled annually in a solid form on the summits of the hills; the glaciers furnish the chief means of escape; superior and inferior snow-line . whiteness of snow; whiteness of ice; round air-bubbles; melting and freezing; conversion of snow into ice by pressure .--colour of water and ice. waves of ether not entangled; they are separated in the prism; they are differently absorbed; colour due to this; water and ice blue; water and ice opaque to radiant heat; long waves shivered on the molecules; experiment; grotto of capri; the laugs of iceland .--colours of the sky. newton's idea; goethe's theory; clausius and brücke; suspended particles; singular effect on a painting explained by goethe; light separated without absorption; reflected and transmitted light; blueness of milk and juices; the sun through london smoke; experiments; blue of the eye; colours of steam; the lake of geneva .--the moraines. glacier loaded along its edges by the ruins of the mountains; lateral moraines; medial moraines; their number _one_ less than the number of tributaries; moraines of the mer de glace; successive shrinkings; glacier tables explained; 'dip' of stones upon the glacier enables us to draw the meridian line; type 'table;' sand cones; moraines engulfed and disgorged; transparency of ice under the moraines .--glacier motion,--preliminary. névé and glacier; first measurements; hugi and agassiz; escher's defeat on the aletsch; piles fixed across the aar glacier by agassiz in ; professor forbes invited by m. agassiz; forbes's first observations on the mer de glace in ; motion of agassiz's piles measured by m. wild; centre of the glacier moves quickest; state of the question .--motion of the mer de glace. the theodolite; mode of measurement; first line; centre point not the quickest; second line; former result confirmed; law of motion sought; the glacier moves through a sinuous valley; effect of flexure; western half of glacier moves quickest; point of maximum motion crosses axis; eastern half moves quickest; locus of point of maximum motion; new law; motion of the géant; motion of the léchaud; squeezing of the tributaries through the neck of the valley at trélaporte; the léchaud a driblet .--ice wall at the tacul,--velocities of top and bottom. first attempt by mr. hirst; second attempt, stakes fixed at top, bottom, and centre; dense fog; the stakes lost; process repeated; velocities determined .--winter motion of the mer de glace. first line, above the montanvert; second line, below the montanvert; ratio of winter to summer motion .--cause of glacier motion,--de saussure's theory. first attempt at a theory by scheuchzer in ; charpentier's theory, or the theory of dilatation; agassiz's theory; altmann and grüner; theory of de saussure, or the sliding theory; in part true; strained interpretation of this theory .--rendu's theory. character of rendu; his essay entitled 'théorie des glaciers de la savoie;' extracts from the essay; he ascribes "circulation" to natural forces; classifies glaciers; assigns the cause of the conversion of snow into ice; notices veined structure; "time and affinity;" notices regelation; diminution of _glaciers réservoirs_; remarkable passage; announces swifter motion of centre; north british review; discrepancies explained by rendu; liquid motion ascribed to glacier; all the phenomena of a river reproduced upon the mer de glace; ratio of side and central velocities; errors removed . anticipations of rendu confirmed by agassiz and forbes; analogies with liquid motion established by forbes; his measurements in ; measurements in and ; measurements of agassiz and wild in , , , and ; agassiz notices the "migration" of the point of swiftest motion; true meaning of this observation; summary of contributions on this part of the question .--forbes's theory. discussions as to its meaning; facts and principles; definition of theory; some experiments on the mer de glace to test the viscosity of the ice .--the crevasses. caused by the motion; ice sculpture; fantastic figures; beauty of the crevasses of the highest glaciers; birth of a crevasse; mechanical origin; line of greatest strain; marginal crevasses; transverse crevasses; longitudinal crevasses; bergschrunds; influence of flexure; why the convex sides of glaciers are most crevassed . further considerations on viscosity; numerical test; formation of crevasses opposed to viscosity .--heat and work. connexion of natural forces; equivalence of heat and work; heat produced by mechanical action; heat consumed in producing work; chemical attractions; attraction of gravitation; amount of heat which would be produced by the stoppage of the earth in its orbit; amount produced by the falling of the earth into the sun; shifting of atoms; heat consumed in molecular work; specific heat; latent heat; 'friability' of ice near its melting point; rotten ice and softened wax . papers presented to the royal society by professor forbes in ; capillary hypothesis of glacier motion; hypothesis examined .--thomson's theory. statement of theory; influence of pressure on the melting point of ice; difficulties of theory; calculation of requisite pressure; actual pressure insufficient .--pressure theory. pressure and tension; possible experiments; ice may be moulded into vases and statuettes or coiled into knots; this no proof of viscosity; actual experiments; a sphere of ice moulded to a lens; a lens moulded to a cylinder; a lump of ice moulded to a cup; straight bars of ice bent; ice thus moulded incapable of being sensibly stretched; when tension is substituted for pressure, analogy with viscous body breaks down .--regelation. faraday's first experiments; freezing together of pieces of ice at °; freezing in hot water; faraday's recent experiments; regelation not due to pressure nor to capillary attraction; it takes place in vacuo; fracture and regelation; no viscidity discovered .--crystallization and internal liquefaction. how crystals are 'nursed;' snow-crystals; crystal stars formed in water; arrangement of atoms of lake ice; dissection of ice by a sunbeam; liquid flowers formed in ice; associated vacuous spots; curious sounds; their explanation; cohesion of water when free from air; liquid snaps like a broken spring; ebullition converted into explosion; noise of crepitation; water-cells in glacier ice; vacuous spots mistaken for bubbles; not flattened by pressure; experiments; cause of regelation .--the moulins. their character; depth of moulin on grindelwald glacier; explanation the grand moulin of the mer de glace; motion of moulins .--dirt-bands of the mer de glace. their discovery by professor forbes; view of bands from a point near the flégère; bands as seen from les charmoz; skew surface of glacier; aspect of bands from the cleft station; origin of bands; tendency to become straight; differences between observers .--veined structure of glaciers. general appearance; grooves upon the glacier; first observations; description by m. guyot; observations of professor forbes; structure and stratification; subject examined; marginal structure; transverse structure; longitudinal structure; experimental illustrations; the structure complementary to the crevasses; glaciers of the oberland, valais, and savoy examined with reference to this question .--the veined structure and differential motion. marginal structure oblique to sides; drag towards the centre; difficulties of theory which ascribes the structure to differential sliding; it persists _across_ the lines of maximum sliding .--the ripple theory of the veined structure. ripples in water supposed to correspond to glacier structure; analysis of theory; observation of the mm. weber; water dropping from an oar; stream cleft by an obstacle; two divergent lines of ripple; single line produced by lateral obstacle; direction of ripples compounded of river's motion and wave motion; structure and ripples due to different causes; their positions also different .--the veined structure and pressure. supposed case of pressed prism of glass; experiments of nature; quartz-pebbles flattened and indented; pressure would produce lamination; tangential action .--the veined structure and the liquefaction of ice by pressure. influence of pressure on melting and boiling points; some substances swell, others shrink in melting; effects of pressure different on the two classes of bodies; theoretic anticipation by mr. james thomson; melting point of ice lowered by pressure; internal liquefaction of a prism of solid ice by pressure; liquefaction in layers; application to the veined structure .--white ice-seams of the glacier du géant. aspect of seams; they sweep across the glacier concentric with structure; structure at the base of the talèfre cascade; crumples; scaling off by pressure; origin of seams of white ice . glacier du géant in a state of longitudinal compression; measurements which prove that its hinder parts are advancing upon those in front; shortening of its undulations; squeezing of white ice-seams; development of veined structure summary appendix index illustrations. the mer de glace.--showing the cleft station at trélaporte, the echelets, the tacul, the périades, and the grand jorasse. _frontispiece_ fig. page . ice minaret . diagram of an angular reflector , . boats' sails inverted by atmospheric refraction . wave-like forms on the mer de glace . glacier table . tributaries of the mer de glace . magnetic boulder of the riffelhorn , , , . luminous trees projected against the sky at sunrise , . snow on the pines , . snow crystals . chasing produced by waves . diagram explanatory of interference . interference spectra, produced by diffraction _to face_ . moraines of the mer de glace " . typical section of a glacier table . locus of the point of maximum motion . inclinations of ice cascade of the glacier des bois . inclinations of mer de glace above l'angle . fantastic mass of ice . diagram explanatory of the mechanical origin of crevasses . diagram showing the line of greatest strain a, b. section and plan of a portion of the lower grindelwald glacier . diagram illustrating the crevassing of convex sides of glacier . diagram illustrating test of viscosity , , , . moulds used in experiments with ice - . liquid flowers in lake ice . dirt-bands of the mer de glace, as seen from a point near the flégère _to face_ . ditto, as seen from les charmoz " . ditto, as seen from the cleft station, trélaporte " . plan of dirt-bands taken from johnson's 'physical atlas' . veined structure on the walls of crevasses . figure explanatory of the marginal structure . plan of part of ice-fall, and of glacier below it (glacier of the rhone) . section of ditto . figure explanatory of longitudinal structure . structure and bedding on the great aletsch glacier , . structure and stratification on the furgge glacier . diagram illustrating differential motion , . diagrams explanatory of the formation of ripples , , . appearance of a prism of ice partially liquefied by pressure. , . figures illustrative of compression and liquefaction of ice. , . sections of white ice-seams , . variations in the dip of the veined structure , . section of three glacier crumples . wall of a crevasse, with incipient crumpling . plan of a stream on the glacier du géant . plan of a seam of white ice on ditto part i. chiefly narrative. ages are your days, ye grand expressors of the present tense and types of permanence; firm ensigns of the fatal being amid these coward shapes of joy and grief that will not bide the seeing. hither we bring our insect miseries to the rocks, and the whole flight with pestering wing vanish and end their murmuring, vanish beside these dedicated blocks. emerson glaciers of the alps. introductory. ( .) in the autumn of i attended the meeting of the british association at liverpool; and, after it was over, availed myself of my position to make an excursion into north wales. guided by a friend who knew the country, i became acquainted with its chief beauties, and concluded the expedition by a visit to bangor and the neighbouring slate quarries of penrhyn. from my boyhood i had been accustomed to handle slates; had seen them used as roofing materials, and had worked the usual amount of arithmetic upon them at school; but now, as i saw the rocks blasted, the broken masses removed to the sheds surrounding the quarry, and there cloven into thin plates, a new interest was excited, and i could not help asking after the cause of this extraordinary property of cleavage. it sufficed to strike the point of an iron instrument into the edge of a plate of rock to cause the mass to yield and open, as wood opens in advance of a wedge driven into it. i walked round the quarry and observed that the planes of cleavage were everywhere parallel; the rock was capable of being split in one direction only, and this direction remained perfectly constant throughout the entire quarry. [sidenote: cleavage of slate rocks.] i was puzzled, and, on expressing my perplexity to my companion, he suggested that the cleavage was nothing more than the layers in which the rock had been originally deposited, and which, by some subsequent disturbance, had been set on end, like the strata of the sandstone rocks and chalk cliffs of alum bay. but though i was too ignorant to combat this notion successfully, it by no means satisfied me. i did not know that at the time of my visit this very question of slaty cleavage was exciting the greatest attention among english geologists, and i quitted the place with that feeling of intellectual discontent which, however unpleasant it may be for a time, is very useful as a stimulant, and perhaps as necessary to the true appreciation of knowledge as a healthy appetite is to the enjoyment of food. on inquiry i found that the subject had been treated by three english writers, professor sedgwick, mr. daniel sharpe, and mr. sorby. from professor sedgwick i learned that cleavage and stratification were things totally distinct from each other; that in many cases the strata could be observed with the cleavage passing through them at a high angle; and that this was the case throughout vast areas in north wales and cumberland. i read the lucid and important memoir of this eminent geologist with great interest: it placed the data of the problem before me, as far as they were then known, and i found myself, to some extent at least, in a condition to appreciate the value of a theoretic explanation. everybody has heard of the force of gravitation, and of that of cohesion; but there is a more subtle play of forces exerted by the molecules of bodies upon each other when these molecules possess sufficient freedom of action. in virtue of such forces, the ultimate particles of matter are enabled to build themselves up into those wondrous edifices which we call crystals. a diamond is a crystal self-erected from atoms of carbon; an amethyst is a crystal built up from particles of silica; iceland spar is a crystal built by particles of carbonate of lime. by artificial means we can allow the particles of bodies the free play necessary to their crystallization. thus a solution of saltpetre exposed to slow evaporation produces crystals of saltpetre; alum crystals of great size and beauty may be obtained in a similar manner; and in the formation of a bit of common sugar-candy there are agencies at play, the contemplation of which, as mere objects of thought, is sufficient to make the wisest philosopher bow down in wonder, and confess himself a child. [sidenote: crystallization theory.] the particles of certain crystalline bodies are found to arrange themselves in layers, like courses of atomic masonry, and along these layers such crystals may be easily cloven into the thinnest laminæ. some crystals possess _one_ such direction in which they may be cloven, some several; some, on the other hand, may be split with different facility in different directions. rock salt may be cloven with equal facility in three directions at right angles to each other; that is, it may be split into cubes; calcspar may be cloven in three directions oblique to each other; that is, into rhomboids. heavy spar may also be cloven in three directions, but one cleavage is much more perfect, or more _eminent_ as it is sometimes called, than the rest. mica is a crystal which cleaves very readily in one direction, and it is sufficiently tough to furnish films of extreme tenuity: finally, any boy, with sufficient skill, who tries a good crystal of sugar-candy in various directions with the blade of his penknife, will find that it possesses one direction in particular, along which, if the blade of the knife be placed and struck, the crystal will split into plates possessing clean and shining surfaces of cleavage. [sidenote: polar forces.] professor sedgwick was intimately acquainted with all these facts, and a great many more, when he investigated the cleavage of slate rocks; and seeing no other explanation open to him, he ascribed to slaty cleavage a crystalline origin. he supposed that the particles of slate rock were acted on, after their deposition, by "polar forces," which so arranged them as to produce the cleavage. according to this theory, therefore, honister crag and the cliffs of penrhyn are to be regarded as portions of enormous crystals; a length of time commensurate with the vastness of the supposed action being assumed to have elapsed between the deposition of the rock and its final crystallization. when, however, we look closely into this bold and beautiful hypothesis, we find that the only analogy which exists between the physical structure of slate rocks and of crystals is this single one of cleavage. such a coincidence might fairly give rise to the conjecture that both were due to a common cause; but there is great difficulty in accepting this as a theoretic truth. when we examine the structure of a slate rock, we find that the substance is composed of the débris of former rocks; that it was once a fine mud, composed of particles of _sensible magnitude_. is it meant that these particles, each taken as a whole, were re-arranged after deposition? if so, the force which effected such an arrangement must be wholly different from that of crystallization, for the latter is essentially _molecular_. what is this force? nature, as far as we know, furnishes none competent, under the conditions, to produce the effect. is it meant that the molecules composing these sensible particles have re-arranged themselves? we find no evidence of such an action in the individual fragments: the mica is still mica, and possesses all the properties of mica; and so of the other ingredients of which the rock is composed. independent of this, that an aggregate of heterogeneous mineral fragments should, without any assignable external cause, so shift its molecules as to produce a plane of cleavage common to them all, is, in my opinion, an assumption too heavy for any theory to bear. nevertheless, the paper of professor sedgwick invested the subject of slaty cleavage with an interest not to be forgotten, and proved the stimulus to further inquiry. the structure of slate rocks was more closely examined; the fossils which they contained were subjected to rigid scrutiny, and their shapes compared with those of the same species taken from other rocks. thus proceeding, the late mr. daniel sharpe found that the fossils contained in slate rocks are distorted in shape, being uniformly flattened out in the direction of the planes of cleavage. here, then, was a fact of capital importance,--the shells became the indicators of an action to which the mass containing them had been subjected; they demonstrated the operation of pressure acting at right angles to the planes of cleavage. [sidenote: mechanical theory.] the more the subject was investigated, the more clearly were the evidences of pressure made out. subsequent to mr. sharpe, mr. sorby entered upon this field of inquiry. with great skill and patience he prepared sections of slate rock, which he submitted to microscopic examination, and his observations showed that the evidences of pressure could be plainly traced, even in his minute specimens. the subject has been since ably followed up by professors haughton, harkness, and others; but to the two gentlemen first mentioned we are, i think, indebted for the prime facts on which rests the _mechanical theory_ of slaty cleavage.[a] [sidenote: lecture at the royal institution.] the observations just referred to showed the co-existence of the two phenomena, but they did not prove that pressure and cleavage stood to each other in the relation of cause and effect. "can the pressure produce the cleavage?" was still an open question, and it was one which mere reasoning, unaided by experiment, was incompetent to answer. sharpe despaired of an experimental solution, regarding our means as inadequate, and our time on earth too short to produce the result. mr. sorby was more hopeful. submitting mixtures of gypsum and oxide of iron scales to pressure, he found that the scales set themselves approximately at right angles to the direction in which the pressure was applied. the position of the scales resembled that of the plates of mica which his researches had disclosed to him in slate rock, and he inferred that the presence of such plates, and of flat or elongated fragments generally, lying all in the same general direction, was the cause of slaty cleavage. at the meeting of the british association at glasgow, in , i had the pleasure of seeing some of mr. sorby's specimens, and, though the cleavage they exhibited was very rough, still, the tendency to yield at right angles to the direction in which the pressure had been applied, appeared sufficiently manifest. at the time now referred to i was engaged, and had been for a long time previously, in examining the effects of pressure upon the magnetic force, and, as far back as , i had noticed that some of the bodies which i had subjected to pressure exhibited a cleavage of surpassing beauty and delicacy. the bearing of such facts upon the present question now forcibly occurred to me. i followed up the observations; visited slate yards and quarries, observed the exfoliation of rails, the fibres of iron, the structure of tiles, pottery, and cheese, and had several practical lessons in the manufacture of puff-paste and other laminated confectionery. my observations, i thought, pointed to a theory of slaty cleavage different from any previously given, and which, moreover, referred a great number of apparently unrelated phenomena to a common cause. on the th of june, , i made them the subject of a friday evening's discourse at the royal institution.[b] [sidenote: origin of researches.] such are the circumstances, apparently remote enough, under which my connexion with glaciers originated. my friend professor huxley was present at the lecture referred to: he was well acquainted with the work of professor forbes, entitled 'travels in the alps,' and he surmised that the question of slaty cleavage, in its new aspect, might have some bearing upon the laminated structure of glacier-ice discussed in the work referred to. he therefore urged me to read the 'travels,' which i did with care, and the book made the same impression upon me that it had produced upon my friend. we were both going to switzerland that year, and it required but a slight modification of our plans to arrange a joint excursion over some of the glaciers of the oberland, and thus afford ourselves the means of observing together the veined structure of the ice. had the results of this arrangement been revealed to me beforehand, i should have paused before entering upon an investigation which required of me so long a renunciation of my old and more favourite pursuits. but no man knows when he commences the examination of a physical problem into what new and complicated mental alliances it may lead him. no fragment of nature can be studied alone; each part is related to every other part; and hence it is, that, following up the links of law which connect phenomena, the physical investigator often finds himself led far beyond the scope of his original intentions, the danger in this respect augmenting in direct proportion to the wish of the inquirer to render his knowledge solid and complete. [sidenote: a boy's book.] when the idea of writing this book first occurred to me, it was not my intention to confine myself to the glaciers alone, but to make the work a vehicle for the familiar explanation of such general physical phenomena as had come under my notice. nor did i intend to address it to a cultured man of science, but to a youth of average intelligence, and furnished with the education which england now offers to the young. i wished indeed to make it a boy's class-book, which should reveal the mode of life, as well as the scientific objects, of an explorer of the alps. the incidents of the past year have caused me to deviate, in some degree, from this intention, but its traces will be sufficiently manifest; and this reference to it will, i trust, excuse an occasional liberty of style and simplicity of treatment which would be out of place if intended for a reader of riper years. footnotes: [a] mr. sorby has drawn my attention to an able and interesting paper by m. bauer, in karsten's 'archiv' for ; in which it is announced that cleavage is a tension of the mass _produced by pressure_. the author refers to the experiments of mr. hopkins as bearing upon the question. [b] see appendix. [sidenote: the oberland. .] expedition of . the oberland. ( .) on the th of august, , i received my alpenstock from the hands of dr. hooker, in the garden of the pension ober, at interlaken. it bore my name, not marked, however, by the vulgar brands of the country, but by the solar beams which had been converged upon it by the pocket lens of my friend. i was the companion of mr. huxley, and our first aim was to cross the wengern alp. light and shadow enriched the crags and green slopes as we advanced up the valley of lauterbrunnen, and each occupied himself with that which most interested him. my companion examined the drift, i the cleavage, while both of us looked with interest at the contortions of the strata to our left, and at the shadowy, unsubstantial aspect of the pines, gleaming through the sunhaze to our right. [sidenote: folded rocks. .] what was the physical condition of the rock when it was thus bent and folded like a pliant mass? was it necessarily softer than it is at present? i do not think so. the shock which would crush a railway carriage, if communicated to it at once, is harmless when distributed over the interval necessary for the pushing in of the buffer. by suddenly stopping a cock from which water flows you may burst the conveyance pipe, while a slow turning of the cock keeps all safe. might not a solid rock by ages of pressure be folded as above? it is a physical axiom that no body is perfectly hard, none perfectly soft, none perfectly elastic. the hardest body subjected to pressure yields, however little, and the same body when the pressure is removed cannot return to its original form. if it did not yield in the slightest degree it would be perfectly hard; if it could completely return to its original shape it would be perfectly elastic. let a pound weight be placed upon a cube of granite; the cube is flattened, though in an infinitesimal degree. let the weight be removed, the cube _remains_ a little flattened; it cannot quite return to its primitive condition. let us call the cube thus flattened no. . starting with no. as a new mass, let the pound weight be laid upon it; the mass yields, and on removing the weight it cannot return to the dimensions of no. ; we have a more flattened mass, no. . proceeding in this manner, it is manifest that by a repetition of the process we should produce a series of masses, each succeeding one more flattened than the former. this appears to be a necessary consequence of the physical axiom referred to above. now if, instead of removing and replacing the weight in the manner supposed, we cause it to rest continuously upon the cube, the flattening, which above was intermittent, will be continuous; no matter how hard the cube may be, there will be a gradual yielding of its mass under the pressure. apply this to squeezed rocks--to those, for example, which form the base of an obelisk like the matterhorn; that this base must yield, seems a certain consequence of the physical constitution of matter: the conclusion seems inevitable that the mountain is sinking by its own weight. let two points be fixed, one near the summit, the other near the base of the obelisk; next year these points will have approached each other. whether the amount of approach in a human lifetime be measureable we know not; but it seems certain that ages would leave their impress upon the mass, and render visible to the eye an action which at present is appreciable by the imagination only. [sidenote: the jungfrau and silberhorn. .] we halted on the night of the th at the jungfrau hotel, and next morning we saw the beams of the rising sun fall upon the peaked snow of the silberhorn. slowly and solemnly the pure white cone appeared to rise higher and higher into the sunlight, being afterwards mottled with gold and gloom, as clouds drifted between it and the sun. i descended alone towards the base of the mountain, making my way through a rugged gorge, the sides of which were strewn with pine-trees, splintered, broken across, and torn up by the roots. i finally reached the end of a glacier, formed by the snow and shattered ice which fall from the shoulders of the jungfrau. the view from this place had a savage magnificence such as i had not previously beheld, and it was not without some slight feeling of awe that i clambered up the end of the glacier. it was the first i had actually stood upon. the loneliness of the place was very impressive, the silence being only broken by fitful gusts of wind, or by the weird rattle of the débris which fell at intervals from the melting ice. [sidenote: avalanches. .] once i noticed what appeared to be the sudden and enormous augmentation of the waters of a cascade, but the sound soon informed me that the increase was due to an avalanche which had chosen the track of the cascade for its rush. soon afterwards my eyes were fixed upon a white slope some thousands of feet above me; i saw the ice give way, and, after a sensible interval, the thunder of another avalanche reached me. a kind of zigzag channel had been worn on the side of the mountain, and through this the avalanche rushed, hidden at intervals, and anon shooting forth, and leaping like a cataract down the precipices. the sound was sometimes continuous, but sometimes broken into rounded explosions which seemed to assert a passionate predominance over the general level of the roar. these avalanches, when they first give way, usually consist of enormous blocks of ice, which are more and more shattered as they descend. partly to the echoes of the first crash, but mainly, i think, to the shock of the harder masses which preserve their cohesion, the explosions which occur during the descent of the avalanche are to be ascribed. much of the ice is crushed to powder; and thus, when an avalanche pours cataract-like over a ledge, the heavier masses, being less influenced by the atmospheric resistance, shoot forward like descending rockets, leaving the lighter powder in trains behind them. such is the material of which a class of the smaller glaciers in the alps is composed. they are the products of avalanches, the crushed ice being recompacted into a solid mass, which exhibits on a smaller scale most of the characteristics of the large glaciers. after three hours' absence i reascended to the hotel, breakfasted, and afterwards returned with mr. huxley to the glacier. while we were engaged upon it the weather suddenly changed; lightning flashed about the summits of the jungfrau, and thunder "leaped" among her crags. heavy rain fell, but it cleared up afterwards with magical speed, and we returned to our hotel. heedless of the forebodings of many prophets of evil weather we set out for grindelwald. the scene from the summit of the little scheideck was exceedingly grand. the upper air exhibited a commotion which we did not experience; clouds were wildly driven against the flanks of the eiger, the jungfrau thundered behind, while in front of us a magnificent rainbow, fixing one of its arms in the valley of grindelwald, and, throwing the other right over the crown of the wetterhorn, clasped the mountain in its embrace. through jagged apertures in the clouds floods of golden light were poured down the sides of the mountain. on the slopes were innumerable chalets, glistening in the sunbeams, herds browsing peacefully and shaking their mellow bells; while the blackness of the pine-trees, crowded into woods, or scattered in pleasant clusters over alp and valley, contrasted forcibly with the lively green of the fields. [sidenote: the heisse platte. .] at grindelwald, on the th, we engaged a strong and competent guide, named christian kaufmann, and proceeded to the lower glacier. after a steep ascent, we gained a point from which we could look down upon the frozen mass. at first the ice presented an appearance of utter confusion, but we soon reached a position where the mechanical conditions of the glacier revealed themselves, and where we might learn, had we not known it before, that confusion is merely the unknown intermixture of laws, and becomes order and beauty when we rise to their comprehension. we reached the so-called eismeer--ice sea. in front of us was the range of the viescherhörner, and a vast snow slope, from which one branch of the glacier was fed. near the base of this _névé_, and surrounded on all sides by ice, lay a brown rock, to which our attention was directed as a place noted for avalanches; on this rock snow or ice never rests, and it is hence called the _heisse platte_--the hot plate. at the base of the rock, and far below it, the glacier was covered with clean crushed ice, which had fallen from a crown of frozen cliffs encircling the brow of the rock. one obelisk in particular signalised itself from all others by its exceeding grace and beauty. its general surface was dazzling white, but from its clefts and fissures issued a delicate blue light, which deepened in hue from the edges inwards. it stood upon a pedestal of its own substance, and seemed as accurately fixed as if rule and plummet had been employed in its erection. fig. represents this beautiful minaret of ice. [sidenote: ice minaret. .] [illustration: fig. . ice minaret.] while we were in sight of the heisse platte, a dozen avalanches rushed downwards from its summit. in most cases we were informed of the descent of an avalanche by the sound, but sometimes the white mass was seen gliding down the rock, and scattering its _smoke_ in the air, long before the sound reached us. it is difficult to reconcile the insignificant appearance presented by avalanches, when seen from a distance, with the volume of sound which they generate; but on this day we saw sufficient to account for the noise. one block of solid ice which we found below the heisse platte measured feet inches in length, feet inches in height, and feet inches in depth. a second mass was feet long, feet high, and feet wide. it contained therefore cubic feet of ice, which had been cast to a distance of nearly yards down the glacier. the shock of such hard and ponderous projectiles against rocks and ice, reinforced by the echoes from the surrounding mountains, will appear sufficient to account for the peals by which their descent is accompanied. [sidenote: echoes of the wetterhorn. .] a second day, in company with dr. hooker, completed the examination of this glacier in ; after which i parted from my friends, mr. huxley intending to rejoin me at the grimsel. on the morning of the th of august i strapped on my knapsack and ascended the green slopes from grindelwald towards the great scheideck. before reaching the summit i frequently heard the wonderful echoes of the wetterhorn. some travellers were in advance of me, and to amuse them an alpine horn was blown. the direct sound was cut off from me by a hill, but the echoes talked down to me from the mountain walls. the sonorous waves arrived after one, two, three, and more reflections, diminishing gradually in intensity, but increasing in softness, as if in its wanderings from crag to crag the sound had undergone a kind of sifting process, leaving all its grossness behind, and returning in delightful flute notes to the ear. let us investigate this point a little. if two looking-glasses be placed perfectly parallel to each other, with a lighted candle between them, an infinite series of images of the candle will be seen at both sides, the images diminishing in brightness the further they recede. but if the looking-glasses, instead of being parallel, enclose an angle, a limited number of images only will be seen. the smaller the angle which the reflectors make with each other, or, in other words, the nearer they approach parallelism, the greater will be the number of images observed. to find the number of images the following is the rule:--divide , or the number of degrees in a circle, by the number of degrees in the angle enclosed by the two mirrors, the quotient will be _one more_ than the number of images; or, counting the object itself, the quotient is always equal to the number of images plus the object. in fig. i have given the number and position of the images produced by two mirrors placed at an angle of °. a b and b c mark the edges of the mirrors, and represents the candle, which, for the sake of simplicity, i have placed midway between them. fix one point of a pair of compasses at b, and with the distance b sweep a circle:--_all the images will be ranged upon the circumference of this circle_. the number of images found by the foregoing rule is , and their positions are marked in the figure by the numbers , , , &c. [illustration: fig. . diagram of an angular reflector.] [sidenote: echoes explained. .] suppose the _ear_ to occupy the place of the eye, and that _a sounding body_ occupies the place of the luminous one, we should then have just as many _echoes_ as we had _images_ in the former case. these echoes would diminish in loudness just as the images of the candle diminish in brightness. at each reflection a portion both of sound and light is lost; hence the oftener light is reflected the dimmer it becomes, and the oftener sound is reflected the fainter it is. now the cliffs of the wetterhorn are so many rough angular reflectors of the sound: some of them send it back directly to the listener, and we have a first echo; some of them send it on to others from which it is again reflected, forming a second echo. thus, by repeated reflection, successive echoes are sent to the ear, until, at length, they become so faint as to be inaudible. the sound, as it diminishes in intensity, appears to come from greater and greater distances, as if it were receding into the mountain solitudes; the final echoes being inexpressibly soft and pure. [sidenote: reichenbach and handeck. .] after crossing the scheideck i descended to meyringen, visiting the reichenbach waterfall on my way. a peculiarity of the descending water here is, that it is broken up in one of the basins into nodular masses, each of which in falling leaves the light foaming mass which surrounds it as a train in the air behind; the effect exactly resembles that of the avalanches of the jungfrau, in which the more solid blocks of ice shoot forward in advance of the lighter débris, which is held back by the friction of the air. next day i ascended the valley of hasli, and observed upon the rocks and mountains the action of ancient glaciers which once filled the valley to the height of more than a thousand feet above its present level. i paused, of course, at the waterfall of handeck, and stood for a time upon the wooden bridge which spans the river at its top. the aar comes gambolling down to the bridge from its parent glacier, takes one short jump upon a projecting ledge, boils up into foam, and then leaps into a chasm, from the bottom of which its roar ascends through the gloom. a rivulet named the aarlenbach joins the aar from the left in the very jaws of the chasm: falling, at first, upon a projection at some depth below the edge, and, rebounding from this, it darts at the aar, and both plunge together like a pair of fighting demons to the bottom of the gorge. the foam of the aarlenbach is white, that of the aar is yellow, and this enables the observer to trace the passage of the one cataract _through_ the other. as i stood upon the bridge the sun shone brightly upon the spray and foam; my shadow was oblique to the river, and hence a symmetrical rainbow could not be formed in the spray, but one half of a lovely bow, with its base in the chasm, leaned over against the opposite rocks, the colours advancing and retreating as the spray shifted its position. i had been watching the water intently for some time, when a little swiss boy, who stood beside me, observed, in his trenchant german, "there plunge stones ever downwards." the stones were palpable enough, carried down by the cataract, and sometimes completely breaking loose from it, but i did not see them until my attention was withdrawn from the water. [sidenote: hut of m. dollfuss. .] on my arrival at the grimsel i found mr. huxley already there, and, after a few minutes' conversation, we decided to spend a night in a hut built by m. dollfuss in , beside the unteraar glacier, about feet above the hospice. we hoped thus to be able to examine the glacier to its origin on the following day. two days' food and some blankets were sent up from the hospice, and, accompanied by our guide, we proceeded to the glacier. [sidenote: hÔtel des neufchÂtelois. .] having climbed a great terminal moraine, and tramped for a considerable time amid loose shingle and boulders, we came upon the ice. the finest specimens of "tables" which i have ever seen are to be found upon this glacier--huge masses of clean granite poised on pedestals of ice. here are also "dirt-cones" of the largest size, and numerous shafts, the forsaken passages of ancient "moulins," some filled with water, others simply with deep blue light. i reserve the description and explanation of both cones and moulins for another place. the surfaces of some of the small pools were sprinkled lightly over with snow, which the water underneath was unable to melt; a coating of snow granules was thus formed, flexible as chain armour, but so close that the air could not escape through it. some bubbles which had risen through the water had lifted the coating here and there into little rounded domes, which, by gentle pressure, could be shifted hither and thither, and several of them collected into one. we reached the hut, the floor of which appeared to be of the original mountain slab; there was a space for cooking walled off from the sleeping-room, half of which was raised above the floor, and contained a quantity of old hay. the number mètres, the height, i suppose, of the place above the sea, was painted on the door, behind which were also the names of several well-known observers--agassiz, forbes, desor, dollfuss, ramsay, and others--cut in the wood. a loft contained a number of instruments for boring, a surveyor's chain, ropes, and other matters. after dinner i made my way alone towards the junction of the finsteraar and lauteraar glaciers, which unite at the abschwung to form the trunk stream of the unteraar glacier. upon the great central moraine which runs between the branches were perched enormous masses of rock, and, under the overhanging ledge of one of these, m. agassiz had his _hôtel des neufchâtelois_. the rock is still there, bearing traces of names now nearly obliterated by the weather, while the fragments around also bear inscriptions. there in the wilderness, in the gray light of evening, these blurred and faded evidences of human activity wore an aspect of sadness. it was a temple of science now in ruins, and i a solitary pilgrim to the desecrated blocks. as the day declined, rain began to fall, and i turned my face towards my new home; where in due time we betook ourselves to our hay, and waited hopefully for the morning. but our hopes were doomed to disappointment. a vast quantity of snow fell during the night, and, when we arose, we found the glacier covered, and the air thick with the descending flakes. we waited, hoping that it might clear up, but noon arrived and passed without improvement; our fire-wood was exhausted, the weather intensely cold, and, according to the men's opinion, hopelessly bad; they opposed the idea of ascending further, and we had therefore no alternative but to pack up and move downwards. what was snow at the higher elevations changed to rain lower down, and drenched us completely before we reached the grimsel. but though thus partially foiled in our design, this visit taught us much regarding the structure and general phenomena of the glacier. [sidenote: the rhone glacier. .] the morning of the th was clear and calm: we rose with the sun, refreshed and strong, and crossed the grimsel pass at an early hour. the view from the summit of the pass was lovely in the extreme; the sky a deep blue, the surrounding summits all enamelled with the newly-fallen snow, which gleamed with dazzling whiteness in the sunlight. it was sunday, and the scene was itself a sabbath, with no sound to disturb its perfect rest. in a lake which we passed the mountains were mirrored without distortion, for there was no motion of the air to ruffle its surface. from the summit of the mayenwand we looked down upon the rhone glacier, and a noble object it seemed,--i hardly know a finer of its kind in the alps. forcing itself through the narrow gorge which holds the ice cascade in its jaws, and where it is greatly riven and dislocated, it spreads out in the valley below in such a manner as clearly to reveal to the mind's eye the nature of the forces to which it is subjected. longfellow's figure is quite correct; the glacier resembles a vast gauntlet, of which the gorge represents the wrist; while the lower glacier, cleft by its fissures into finger-like ridges, is typified by the hand. furnishing ourselves with provisions at the adjacent inn, we devoted some hours to the examination of the lower portion of the glacier. the dirt upon its surface was arranged in grooves as fine as if produced by the passage of a rake, while the laminated structure of the deeper ice always corresponded to the superficial grooving. we found several shafts, some empty, some filled with water. at one place our attention was attracted by a singular noise, evidently produced by the forcing of air and water through passages in the body of the glacier; the sound rose and fell for several minutes, like a kind of intermittent snore, reminding one of hugi's hypothesis that the glacier was alive. [sidenote: rings around the sun. .] we afterwards climbed to a point from which the whole glacier was visible to us from its origin to its end. adjacent to us rose the mighty mass of the finsteraarhorn, the monarch of the oberland. the galenstock was also at hand, while round about the _névé_ of the glacier a mountain wall projected its jagged outline against the sky. at a distance was the grand cone of the weisshorn, then, and i believe still, unscaled;[a] further to the left the magnificent peaks of the mischabel; while between them, in savage isolation, stood the obelisk of the matterhorn. near us was the chain of the furca, all covered with shining snow, while overhead the dark blue of the firmament so influenced the general scene as to inspire a sentiment of wonder approaching to awe. we descended to the glacier, and proceeded towards its source. as we advanced an unusual light fell upon the mountains, and looking upwards we saw a series of coloured rings, drawn like a vivid circular rainbow quite round the sun. between the orb and us spread a thin veil of cloud on which the circles were painted; the western side of the veil soon melted away, and with it the colours, but the eastern half remained a quarter of an hour longer, and then in its turn disappeared. the crevasses became more frequent and dangerous as we ascended. they were usually furnished with overhanging eaves of snow, from which long icicles depended, and to tread on which might be fatal. we were near the source of the glacier, but the time necessary to reach it was nevertheless indefinite, so great was the entanglement of fissures. we followed one huge chasm for some hundreds of yards, hoping to cross it; but after half an hour's fruitless effort we found ourselves baffled and forced to retrace our steps. [sidenote: spirit of the brocken. .] the sun was sloping to the west, and we thought it wise to return; so down the glacier we went, mingling our footsteps with the tracks of chamois, while the frightened marmots piped incessantly from the rocks. we reached the land once more, and halted for a time to look upon the scene within view. the marvellous blueness of the sky in the earlier part of the day indicated that the air was charged, almost to saturation, with transparent aqueous vapour. as the sun sank the shadow of the finsteraarhorn was cast through the adjacent atmosphere, which, thus deprived of the direct rays, curdled up into visible fog. the condensed vapour moved slowly along the flanks of the mountain, and poured itself cataract-like into the valley of the rhone. here it met the sun again, which reduced it once more to the invisible state. thus, though there was an incessant supply from the generator behind, the fog made no progress; as in the case of the moving glacier, the end of the cloud-river remained stationary where consumption was equal to supply. proceeding along the mountain to the furca, we found the valley at the further side of the pass also filled with fog, which rose, like a wall, high above the region of actual shadow. once on turning a corner an exclamation of surprise burst simultaneously from my companion and myself. before each of us and against the wall of fog, stood a spectral image of a man, of colossal dimensions; dark as a whole, but bounded by a coloured outline. we stretched forth our arms; the spectres did the same. we raised our alpenstocks; the spectres also flourished their bâtons. all our actions were imitated by these fringed and gigantic shades. we had, in fact, _the spirit of the brocken_ before us in perfection. at the time here referred to i had had but little experience of alpine phenomena. i had been through the oberland in , but was then too ignorant to learn much from my excursion. hence the novelty of this day's experience may have rendered it impressive: still even now i think there was an intrinsic grandeur in its phenomena which entitles the day to rank with the most remarkable that i have spent among the alps. at the furca, to my great regret, the joint ramblings of my friend and myself ended; i parted from him on the mountain side, and watched him descending, till the gray of evening finally hid him from my view. footnotes: [a] the weisshorn was first scaled, by tyndall, in .--l. c. t. [sidenote: the tyrol. .] the tyrol. ( .) my subsequent destination was vienna; but i wished to associate with my journey thither a visit to some of the glaciers of the tyrol. at landeck, on the th of august, i learned that the nearest glacier was that adjacent to the gebatsch alp, at the head of the kaunserthal; and on the following morning i was on my way towards this valley. i sought to obtain a guide at kaltebrunnen, but failed; and afterwards walked to the little hamlet of feuchten, where i put up at a very lonely inn. my host, i believe, had never seen an englishman, but he had heard of such, and remarked to me in his patois with emphasis, "_die engländer sind die kühnsten leute in dieser welt._" through his mediation i secured a chamois-hunter, named johann auer, to be my guide, and next morning i started with this man up the valley. the sun, as we ascended, smote the earth and us with great power; high mountains flanked us on either side, while in front of us, closing the view, was the mass of the weisskugel, covered with snow. at three o'clock we came in sight of the glacier, and soon afterwards i made the acquaintance of the _senner_ or cheesemakers of the gebatsch alp. [sidenote: the gebatsch alp. .] the chief of these was a fine tall fellow, with free, frank countenance, which, however, had a dash of the mountain wildness in it. his feet were bare, he wore breeches, and fragments of stockings partially covered his legs, leaving a black zone between the upper rim of the sock and the breeches. his feet and face were of the same swarthy hue; still he was handsome, and in a measure pleasant to look upon. he asked me what he could cook for me, and i requested some bread and milk; the former was a month old, the latter was fresh and delicious, and on these i fared sumptuously. i went to the glacier afterwards with my guide, and remained upon the ice until twilight, when we returned, guided by no path, but passing amid crags grasped by the gnarled roots of the pine, through green dells, and over bilberry knolls of exquisite colouring. my guide kept in advance of me singing a tyrolese melody, and his song and the surrounding scene revived and realised all the impressions of my boyhood regarding the tyrol. milking was over when we returned to the chalet, which now contained four men exclusive of myself and my guide. a fire of pine logs was made upon a platform of stone, elevated three feet above the floor; there was no chimney, as the smoke found ample vent through the holes and fissures in the sides and roof. the men were all intensely sunburnt, the legitimate brown deepening into black with beard and dirt. the chief senner prepared supper, breaking eggs into a dish, and using his black fingers to empty the shell when the albumen was refractory. a fine erect figure he was as he stood in the glowing light of the fire. all the men were smoking, and now and then a brand was taken from the fire to light a renewed pipe, and a ruddy glare flung thereby over the wild countenance of the smoker. in one corner of the chalet, and raised high above the ground, was a large bed, covered with clothes of the most dubious black-brown hue; at one end was a little water-wheel turned by a brook, which communicated motion to a churndash which made the butter. the beams and rafters were covered with cheeses, drying in the warm smoke. the senner, at my request, showed me his storeroom, and explained to me the process of making cheese, its interest to me consisting in its bearing upon the question of slaty cleavage. three gigantic masses of butter were in the room, and i amused my host by calling them butter-glaciers. soon afterwards a bit of cotton was stuck in a lump of grease, which was placed in a lantern, and the wick ignited; the chamois-hunter took it, and led the way to our resting-place, i having previously declined a good-natured invitation to sleep in the big black bed already referred to. [sidenote: an alpine chalet. .] there was a cowhouse near the chalet, and above it, raised on pillars of pine, and approached by a ladder, was a loft, which contained a quantity of dry hay: this my guide shook to soften the lumps, and erected an eminence for my head. i lay down, drawing my plaid over me, but auer affirmed that this would not be a sufficient protection against the cold; he therefore piled hay upon me to the shoulders, and proposed covering up my head also. this, however, i declined, though the biting coldness of the air, which sometimes blew in upon us, afterwards proved to me the wisdom of the suggestion. having set me right, my chamois-hunter prepared a place for himself, and soon his heavy breathing informed me that he was in a state of bliss which i could only envy. one by one the stars crossed the apertures in the roof. once the pleiades hung above me like a cluster of gems; i tried to admire them, but there was no fervour in my admiration. sometimes i dozed, but always as this was about to deepen into positive sleep it was rudely broken by the clamour of a group of pigs which occupied the ground-floor of our dwelling. the object of each individual of the group was to secure for himself the maximum amount of heat, and hence the outside members were incessantly trying to become inside ones. it was the struggle of radical and conservative among the pachyderms, the politics being determined by the accident of position. [sidenote: the gebatsch glacier. .] i rose at five o'clock on the st of september, and after a breakfast of black bread and milk ascended the glacier as far as practicable. we once quitted it, crossed a promontory, and descended upon one of its branches, which was flanked by some fine old moraines. we here came upon a group of seven marmots, which with yells of terror scattered themselves among the rocks. the points of the glacier beyond my reach i examined through a telescope; along the faces of the sections the lines of stratification were clearly shown; and in many places where the mass showed manifest signs of lateral pressure, i thought i could observe the cleavage passing though the strata. the point, however, was too important to rest upon an observation made from such a distance, and i therefore abstained from mentioning it subsequently. i examined the fissures and the veining, and noticed how the latter became most perfect in places where the pressure was greatest. the effect of _oblique_ pressure was also finely shown: at one place the thrust of the descending glacier was opposed by the resistance offered by the side of the valley, the direction of the force being oblique to the side; the consequence was a structure nearly parallel to the valley, and consequently oblique to the thrust which i believe to be its cause. [sidenote: a chamois on the rocks. .] after five hours' examination we returned to our chalet, where we refreshed ourselves, put our things in order, and faced a nameless "joch," or pass; our aim being to cross the mountains into the valley of lantaufer, and reach graun that evening. after a rough ascent over the alp we came to the dead crag, where the weather had broken up the mountains into ruinous heaps of rock and shingle. we reached the end of a glacier, the ice of which was covered by sloppy snow, and at some distance up it came upon an islet of stones and débris, where we paused to rest ourselves. my guide, as usual, ranged over the summits with his telescope, and at length exclaimed, "i see a chamois." the creature stood upon a cliff some hundreds of yards to our left, and seemed to watch our movements. it was a most graceful animal, and its life and beauty stood out in forcible antithesis to the surrounding savagery and death. on the steep slopes of the glacier i was assisted by the hand of my guide. in fact, on this day i deemed places dangerous, and dreaded them as such, which subsequent practice enabled me to regard with perfect indifference; so much does what we call courage depend upon habit, or on the fact of knowing that we have really nothing to fear. doubtless there are times when a climber has to make up his mind for very unpleasant possibilities, and even gather calmness from the contemplation of the worst; but in most cases i should say that his courage is derived from the latent feeling that the chances of safety are immensely in his favour. [sidenote: passage of a joch. .] after a tough struggle we reached the narrow row of crags which form the crest of the pass, and looked into the world of mountain and cloud on the other side. the scene was one of stern grandeur--the misty lights and deep cloud-glooms being so disposed as to augment the impression of vastness which the scene conveyed. the breeze at the summit was exceedingly keen, but it gave our muscles tone, and we sprang swiftly downward through the yielding débris which here overlies the mountain, and in which we sometimes sank to the knees. lower down we came once more upon the ice. the glacier had at one place melted away from its bounding cliff, which rose vertically to our right, while a wall of ice or feet high was on our left. between the two was a narrow passage, the floor of which was snow, which i knew to be hollow beneath: my companion, however, was in advance of me, and he being the heavier man, where he trod i followed without hesitation. on turning an angle of the rock i noticed an expression of concern upon his countenance, and he muttered audibly, "i did not expect this." the snow-floor had, in fact, given way, and exposed to view a clear green lake, one boundary of which was a sheer precipice of rock, and the other the aforesaid wall of ice; the latter, however, curved a little at its base, so as to form a short steep slope which overhung the water. my guide first tried the slope alone; biting the ice with his shoe-nails, and holding on by the spike of his bâton, he reached the other side. he then returned, and, divesting myself of all superfluous clothes, as a preparation for the plunge which i fully expected, i also passed in safety. probably the consciousness that i had water to fall into instead of pure space, enabled me to get across without anxiety or mischance; but had i, like my guide, been unable to swim, my feelings would have been far different. this accomplished, we went swiftly down the valley, and the more i saw of my guide the more i liked him. he might, if he wished, have made his day's journey shorter by stopping before he reached graun, but he would not do so. every word he said to me regarding distances was true, and there was not the slightest desire shown to magnify his own labour. i learnt by mere accident that the day's work had cut up his feet, but his cheerfulness and energy did not bate a jot till he had landed me in the black eagle at graun. next morning he came to my room, and said that he felt sufficiently refreshed to return home. i paid him what i owed him, when he took my hand, and, silently bending down his head, kissed it; then, standing erect, he stretched forth his right hand, which i grasped firmly in mine, and bade him farewell; and thus i parted from johann auer, my brave and truthful chamois-hunter. on the following day i met dr. frankland in the finstermuntz pass, and that night we bivouacked together at mals. heavy rain fell throughout the night, but it came from a region high above that of liquidity. it was first snow, which, as it descended through the warmer strata of the atmosphere, was reduced to water. overhead, in the air, might be traced a surface, below which the precipitate was liquid, above which it was solid; and this surface, intersecting the mountains which surround mals, marked upon them a beautifully-defined _snow-line_, below which the pines were dark and the pastures green, but above which pines and pastures and crags were covered with the freshly-fallen snow. [sidenote: the stelvio. .] [sidenote: colour of fresh snow. .] on the nd of september we crossed the stelvio. the brown cone of the well-known madatschspitze was clear, but the higher summits were clouded, and the fragments of sunshine which reached the lower world wandered like gleams of fluorescent light over the glaciers. near the snow-line the partial melting of the snow had rendered it coarsely granular, but as we ascended it became finer, and the light emitted from its cracks and cavities a pure and deep blue. when a staff was driven into the snow low down the mountain, the colour of the light in the orifice was scarcely sensibly blue, but higher up this increased in a wonderful degree, and at the summit the effect was marvellous. i struck my staff into the snow, and turned it round and round; the surrounding snow cracked repeatedly, and flashes of blue light issued from the fissures. the fragments of snow that adhered to the staff were, by contrast, of a beautiful pink yellow, so that, on moving the staff with such fragments attached to it up and down, it was difficult to resist the impression that a pink flame was ascending and descending in the hole. as we went down the other side of the pass, the effect became more and more feeble, until, near the snow-line, it almost wholly disappeared. we remained that night at the baths of bormio, but the following afternoon being fine we wished to avail ourselves of the fair weather to witness the scene from the summit of the pass. twilight came on before we reached santa maria, but a gorgeous orange overspread the western horizon, from which we hoped to derive sufficient light. it was a little too late when we reached the top, but still the scene was magnificent. a multitude of mountains raised their crowns towards heaven, while above all rose the snow-white cone of the ortler. far into the valley the giant stretched his granite limbs, until they were hid from us by darkness. as this deepened, the heavens became more and more crowded with stars, which blazed like gems over the heads of the mountains. at times the silence was perfect, unbroken save by the crackling of the frozen snow beneath our own feet; while at other times a breeze would swoop down upon us, keen and hostile, scattering the snow from the roofs of the wooden galleries in frozen powder over us. long after night had set in, a ghastly gleam rested upon the summit of the ortler, while the peaks in front deepened to a dusky neutral tint, the more distant ones being lost in gloom. we descended at a swift pace to trafoi, which we reached before p.m. [sidenote: singular hailstorm. .] meran was our next resting-place, whence we turned through the schnalzerthal to unserfrau, and thence over the hochjoch to fend. from a religious procession we took a guide, who, though partly intoxicated, did his duty well. before reaching the summit of the pass we were assailed by a violent hailstorm, each hailstone being a frozen cone with a rounded end. had not their motion through the air something to do with the shape of these hailstones? the theory of meteorites now generally accepted is that they are small planetary bodies drawn to the earth by gravity, and brought to incandescence by friction against the earth's atmosphere. such a body moving through the atmosphere must have condensed hot air in front of it, and rarefied cool air behind it; and the same is true to a small extent of a hailstone. this distribution of temperature must, i imagine, have some influence on the shape of the stone. possibly also the stratified appearance of some hailstones may be connected with this action.[a] [sidenote: the hochjoch and fend. .] the hail ceased and the heights above us cleared as we ascended. at the top of the pass we found ourselves on the verge of a great _névé_, which lay between two ranges of summits, sloping down to the base of each range from a high and rounded centre: a wilder glacier scene i have scarcely witnessed. wishing to obtain a more perfect view of the region, i diverged from the track followed by dr. frankland and the guide, and climbed a ridge of snow about half a mile to the right of them. a glorious expanse was before me, stretching itself in vast undulations, and heaping itself here and there into mountainous cones, white and pure, with the deep blue heaven behind them. here i had my first experience of hidden crevasses, and to my extreme astonishment once found myself in the jaws of a fissure of whose existence i had not the slightest notice. such accidents have often occurred to me since, but the impression made by the first is likely to remain the strongest. it was dark when we reached the wretched wirthshaus at fend, where, badly fed, badly lodged, and disturbed by the noise of innumerable rats, we spent the night. thus ended my brief glacier expedition of ; and on the observations then made, and on subsequent experiments, was founded a paper presented to the royal society by mr. huxley and myself.[b] footnotes: [a] i take the following account of a grander storm of the above character from hooker's 'himalayan journals,' vol. ii. p. . "on the th (march, ) we had a change in the weather: a violent storm from the south-west occurred at noon, with hail of a strange form, the stones being sections of hollow spheres, half an inch across and upwards, formed of cones with truncated apices and convex bases: these cones were aggregated together with their bases outwards. the large masses were followed by a shower of the separate conical pieces, and that by heavy rain. on the mountains this storm was most severe: the stones lay at darjeeling for seven days, congealed into masses of ice several feet long and a foot thick in sheltered places: at purneah, fifty miles south, stones one and two inches across fell, probably as whole spheres." [b] 'phil. trans.' , pp. - .--l. c. t. [sidenote: the lake of geneva. .] expedition of . the lake of geneva. ( .) the time occupied in the observations of embraced about five whole days; and though these days were laborious and instructive, still so short a time proved to be wholly incommensurate with the claims of so wide a problem. during the subsequent experimental treatment of the subject, i had often occasion to feel the incompleteness of my knowledge, and hence arose the desire to make a second expedition to the alps, for the purpose of expanding, fortifying, or, if necessary, correcting first impressions. on thursday, the th of july, , i found myself upon the lake of geneva, proceeding towards vevey. i had long wished to see the waters of this renowned inland sea, the colour of which is perhaps more interesting to the man of science than to the poets who have sung about it. long ago its depth of blue excited attention, but no systematic examination of the subject has, so far as i know, been attempted. it may be that the lake simply exhibits the colour of pure water. ice is blue, and it is reasonable to suppose that the liquid obtained from the fusion of ice is of the same colour; but still the question presses--"is the blue of the lake of geneva to be entirely accounted for in this way?" the attempts which have been made to explain it otherwise show that at least a doubt exists as to the sufficiency of the above explanation. [sidenote: blueness of the water. .] it is only in its deeper portions that the colour of the lake is properly seen. where the bottom comes into view the pure effect of the water is disturbed; but where the water is deep the colour is deep: between rolle and nyon for example, the blue is superb. where the blue was deepest, however, it gave me the impression of turbidity rather than of deep transparency. at the upper portion of the lake the water through which the steamer passed was of a blue green. wishing to see the place where the rhone enters the lake, i walked on the morning of the th from villeneuve to novelle, and thence through the woods to the river side. proceeding along an embankment, raised to defend the adjacent land from the incursions of the river, an hour brought me to the place where it empties itself into the lake. the contrast between the two waters was very great: the river was almost white with the finely divided matter which it held in suspension; while the lake at some distance was of a deep ultramarine. the lake in fact forms a reservoir where the particles held in suspension by the river have time to subside, and its waters to become pure. the subsidence of course takes place most copiously at the head of the lake; and here the deposit continues to form new land, adding year by year to the thousands of acres which it has already left behind it, and invading more and more the space occupied by the water. innumerable plates of mica spangled the fine sand which the river brought down, and these, mixing with the water, and flashing like minute mirrors as the sun's rays fell upon them, gave the otherwise muddy stream a silvery appearance. had i an opportunity i would make the following experiments:-- (_a_.) compare the colour of the light transmitted by a column of the lake water fifteen feet long with that transmitted by a second column, of the same length, derived from the melting of freshly fallen mountain snow. (_b_.) compare in the same manner the colour of the ordinary water of the lake with that of the same water after careful distillation. (_c_.) strictly examine whether the light transmitted by the ordinary water contains an excess of red over that transmitted by the distilled water: this latter point, as will be seen farther on, is one of peculiar interest. the length is fixed at fifteen feet, because i have found this length extremely efficient in similar experiments. [illustration: fig. , . boats' sails inverted by atmospheric refraction.] [sidenote: atmospheric refraction. .] on returning to the pier at villeneuve, a peculiar flickering motion was manifest upon the surface of the distant portions of the lake, and i soon noticed that the coast line was inverted by atmospheric refraction. it required a long distance to produce the effect: no trace of it was seen about the castle of chillon, but at vevey and beyond it, the whole coast was clearly inverted; and the houses on the margin of the lake were also imaged to a certain height. two boats at a considerable distance presented the appearance sketched in figs. and ; the hull of each, except a small portion at the end, was invisible, but the sails seemed lifted up high in the air, with their inverted images below; as the boats drew nearer the hulls appeared inverted, the apparent height of the vessel above the surface of the lake being thereby nearly doubled, while the sails and higher objects, in these cases, were almost completely cut away. when viewed through a telescope the sensible horizon of the lake presented a billowy tumultuous appearance, fragments being incessantly detached from it and suspended in the air. [sidenote: mirage. .] the explanation of this effect is the same as that of the mirage of the desert, which may be found in almost any book on physics, and which so tantalized the french soldiers in egypt. they often mistook this aërial inversion for the reflection from a lake, and on trial found hot and sterile sand at the place where they expected refreshing waters. the effect was shown by monge, one of the learned men who accompanied the expedition, to be due to the total reflection of very oblique rays at the upper surface of the layer of rarefied air which was nearest to the heated earth. a sandy plain, in the early part of the day, is peculiarly favourable for the production of such effects; and on the extensive flat strand which stretches between mont st. michel and the coast adjacent to avranches in normandy, i have noticed mont tombeline reflected as if glass instead of sand surrounded it and formed its mirror. [sidenote: chamouni and the montanvert. .] chamouni and the montanvert. ( .) on the evening of the th of july i reached chamouni; the weather was not quite clear, but it was promising; white cumuli had floated round mont blanc during the day, but these diminished more and more, and the light of the setting sun was of that lingering rosy hue which bodes good weather. two parallel beams of a purple tinge were drawn by the shadows of the adjacent peaks, straight across the glacier des bossons, and the glacier des pèlerins was also steeped for a time in the same purple light. once when the surrounding red illumination was strong, the shadows of the grands mulets falling upon the adjacent snow appeared of a vivid green. this green belonged to the class of _subjective_ colours, or colours produced by contrast, about which a volume might be written. the eye received the impression of green, but the colour was not external to the eye. place a red wafer on white paper, and look at it intently, it will be surrounded in a little time by a green fringe: move the wafer bodily away, and the entire space which it occupied upon the paper will appear green. a body may have its proper colour entirely masked in this way. let a red wafer be attached to a piece of red glass, and from a moderately illuminated position let the sky be regarded through the glass; the wafer will appear of a vivid green. if a strong beam of light be sent through a red glass and caused to fall upon a screen, which at the same time is moderately illuminated by a separate source of white light, an opaque body placed in the path of the beam will cast a green shadow upon the screen which may be seen by several hundred persons at once. if a blue glass be used, the shadow will be yellow, which is the complementary colour to blue. [sidenote: coloured shadows. .] when we suddenly pass from open sunlight to a moderately illuminated room, it appears dark at first, but after a little time the eye regains the power of seeing objects distinctly. thus one effect of light upon the eye is to render it less sensitive, and light of any particular colour falling upon the eye blunts its appreciation of that colour. let us apply this to the shadow upon the screen. this shadow is moderately illuminated by a jet of white light; but the space surrounding it is red, the effect of which upon the eye is to blind it in some degree to the perception of red. hence, when the feeble white light of the shadow reaches the eye, the red component of this light is, as it were, abstracted from it, and the eye sees the residual colour, which is green. a similar explanation applies to the shadows of the grands mulets. on the th of july i was joined by my friend mr. thomas hirst, and on the th we examined together the end of the mer de glace. in former times the whole volume of the arveiron escaped from beneath the ice at the end of the glacier, forming a fine arch at its place of issue. this year a fraction only of the water thus found egress; the greater portion of it escaping laterally from the glacier at the summit of the rocks called _les mottets_, down which it tumbled in a fine cascade. the vault at the end of the glacier was nevertheless respectable, and rather tempting to a traveller in search of information regarding the structure of the ice. perhaps, however, nature meant to give me a friendly warning at the outset, for, while speculating as to the wisdom of entering the cavern, it suddenly gave way, and, with a crash which rivalled thunder, the roof strewed itself in ruins upon the floor. [sidenote: sunrise at chamouni. .] many years ago i had read with delight coleridge's poem entitled 'sunrise in the valley of chamouni,' and to witness in all perfection the scene described by the poet, i waited at chamouni a day longer than was otherwise necessary. on the morning of wednesday, the th of july, i rose before the sun; mont blanc and his wondrous staff of aiguilles were without a cloud; eastward the sky was of a pale orange which gradually shaded off to a kind of rosy violet, and this again blended by imperceptible degrees with the deep zenithal blue. the morning star was still shining to the right, and the moon also turned a pale face towards the rising day. the valley was full of music; from the adjacent woods issued a gush of song, while the sound of the arve formed a suitable bass to the shriller melody of the birds. the mountain rose for a time cold and grand, with no apparent stain upon his snows. suddenly the sunbeams struck his crown and converted it into a boss of gold. for some time it remained the only gilded summit in view, holding communion with the dawn while all the others waited in silence. these, in the order of their heights, came afterwards, relaxing, as the sunbeams struck each in succession, into a blush and smile. [sidenote: glacier des bois. .] on the same day we had our luggage transported to the montanvert, while we clambered along the lateral moraine of the glacier to the chapeau. the rocks alongside the glacier were beautifully scratched and polished, and i paid particular attention to them, for the purpose of furnishing myself with a key to ancient glacier action. the scene to my right was one of the most wonderful i had ever witnessed. along the entire slope of the glacier des bois, the ice was cleft and riven into the most striking and fantastic forms. it had not yet suffered much from the wasting influence of the summer weather, but its towers and minarets sprang from the general mass with clean chiselled outlines. some stood erect, others leaned, while the white débris, strewn here and there over the glacier, showed where the wintry edifices had fallen, breaking themselves to pieces, and grinding the masses on which they fell to powder. some of them gave way during our inspection of the place, and shook the valley with the reverberated noise of their fall. i endeavoured to get near them, but failed; the chasms at the margin of the glacier were too dangerous, and the stones resting upon the heights too loosely poised to render persistence in the attempt excusable. we subsequently crossed the glacier to the montanvert, and i formally took up my position there. the rooms of the hotel were separated from each other by wooden partitions merely, and thus the noise of early risers in one room was plainly heard in the next. for the sake of quiet, therefore, i had my bed placed in the _château_ next door,--a little octagonal building erected by some kind and sentimental frenchman, and dedicated "_à la nature_." my host at first demurred, thinking the place not "_propre_," but i insisted, and he acquiesced. true the stone floor was dark with moisture, and on the walls a glistening was here and there observable, which suggested rheumatism, and other penalties, but i had had no experience of rheumatism, and trusted to the strength which mountain air and exercise were sure to give me, for power to resist its attacks. moreover, to dispel some of the humidity, it was agreed that a large pine fire should be made there on necessary occasions. [sidenote: quarters at the montanvert. .] though singularly favoured on the whole, still our residence at the montanvert was sufficiently long to give us specimens of all kinds of weather; and thus my château derived an interest from the mutations of external nature. sometimes no breath disturbed the perfect serenity of the night, and the moon, set in a black-blue sky, turned a face of almost supernatural brightness to the mountains, while in her absence the thick-strewn stars alone flashed and twinkled through the transparent air. sometimes dull dank fog choked the valley, and heavy rain plashed upon the stones outside. on two or three occasions we were favoured by a thunderstorm, every peal of which broke into a hundred echoes, while the seams of lightning which ran through the heavens produced a wonderful intermittence of gloom and glare. and as i sat within, musing on the experiences of the day, with my pine logs crackling, and the ruddy fire-light gleaming over the walls, and lending animation to the visages sketched upon them with charcoal by the guides, i felt that my position was in every way worthy of a student of nature. the mer de glace. ( .) [sidenote: a river of ice. .] the name "mer de glace" has doubtless led many who have never seen this glacier to a totally erroneous conception of its character. misled probably by this term, a distinguished writer, for example, defines a glacier to be a sheet of ice spread out upon the slope of a mountain; whereas the mer de glace is indeed a _river_, and not a _sea_ of ice. but certain forms upon its surface, often noticed and described, and which i saw for the first time from the window of our hotel on the morning of the th of july, suggest at once the origin of the name. the glacier here has the appearance of a sea which, after it had been tossed by a storm, had suddenly stiffened into rest. the ridges upon its surface accurately resemble waves in shape, and this singular appearance is produced in the following way:-- some distance above the montanvert--opposite to the echelets--the glacier, in passing down an incline, is rent by deep fissures, between each two of which a ridge of ice intervenes. at first the edges of these ridges are sharp and angular, but they are soon sculptured off by the action of the sun. the bearing of the mer de glace being approximately north and south, the sun at mid-day shines down the glacier, or rather very obliquely across it; and the consequence is, that the fronts of the ridges, which look downward, remain in shadow all the day, while the backs of the ridges, which look up the glacier, meet the direct stroke of the solar rays. the ridges thus acted upon have their hindmost angles wasted off and converted into slopes which represent the _back_ of a wave, while the opposite sides of the ridges, which are protected from the sun, preserve their steepness, and represent the _front_ of the wave. fig. will render my meaning at once plain. [sidenote: frozen waves. .] [illustration: fig. . wave-like forms on the mer de glace.] the dotted lines are intended to represent three of the ridges into which the glacier is divided, with their interposed fissures; the dots representing the boundaries of the ridges when the glacier is first broken. the parallel shading lines represent the direction of the sun's rays, which, falling obliquely upon the ridges, waste away the right-hand corners, and finally produce wave-like forms. we spent a day or two in making the general acquaintance of the glacier. on the th we ascended till we came to the rim of the talèfre basin, from which we had a good view of the glacier system of the region. the laminated structure of the ice was a point which particularly interested me; and as i saw the exposed sections of the _névé_, counted the lines of stratification, and compared these with the lines upon the ends of the secondary glaciers, i felt the absolute necessity either of connecting the veined _structure_ with the _strata_ by a continuous chain of observations, or of proving by ocular evidence that they were totally distinct from each other. i was well acquainted with the literature of the subject, but nothing that i had read was sufficient to prove what i required. strictly speaking, nothing that had been written upon the subject rose above the domain of _opinion_, while i felt that without absolute _demonstration_ the question would never be set at rest. [illustration: fig. . glacier table.] [sidenote: glacier tables. .] on this day we saw some fine glacier tables; flat masses of rock, raised high upon columns of ice: fig. is a sketch of one of the finest of them. some of them fell from their pedestals while we were near them, and the clean ice-surfaces which they left behind sparkled with minute stars as the small bubbles of air ruptured the film of water by which they were overspread. i also noticed that "petit bruit de crépitation," to which m. agassiz alludes, and which he refers to the rupture of the ice by the expansion of the air-bubbles contained within it. when i first read agassiz's account of it, i thought it might be produced by the rupture of the minute air-bubbles which incessantly escape from the glacier. this, doubtless, produces an effect, but there is something in the character of the sound to be referred, i think, to a less obvious cause, which i shall notice further on. [sidenote: first sight of the dirt-bands. .] at six p.m. this day i reached the montanvert; and the same evening, wrapping my plaid around me, i wandered up towards charmoz, and from its heights observed, as they had been observed fifteen years previously by professor forbes, the _dirt-bands_ of the mer de glace. they were different from any i had previously seen, and i felt a strong desire to trace them to their origin. content, however, with the performance of the day, and feeling healthily tired by it, i lay down upon the bilberry bushes and fell asleep. it was dark when i awoke, and i experienced some difficulty and risk in getting down from the petty eminence referred to. the illumination of the glacier, as remarked by professor forbes, has great influence upon the appearance of the bands; they are best seen in a subdued light, and i think for the following reasons:-- the dirt-bands are seen simply because they send less light to the eye than the cleaner portions of the glacier which lie between them; two surfaces, differently illuminated, are presented to the eye, and it is found that this difference is more observable when the light is that of evening than when it is that of noon. it is only within certain limits that the eye is able to perceive differences of intensity in different lights; beyond a certain intensity, if i may use the expression, light ceases to be light, and becomes mere pain. the naked eye can detect no difference in brightness between the electric light and the lime light, although, when we come to strict measurement, the former may possess many times the intensity of the latter. it follows from this that we might reduce the ordinary electric light to a fraction of its intensity, without any perceptible change of brightness to the naked eye which looks at it. but if we reduce the lime light in the same proportion the effect would be very different. this light lies much nearer to the limit at which the eye can appreciate differences of brightness, and its reduction might bring it quite within this limit, and make it sensibly dimmer than before. hence we see that when two sources of intense light are presented to the eye, by reducing both the lights in the same proportion, the _difference_ between them may become more perceptible. [sidenote: bands seen best by twilight. .] now the dirt-bands and the spaces between them resemble, in some measure, the two lights above mentioned. by the full glare of noon both are so strongly illuminated that the difference which the eye perceives is very small; as the evening advances the light of both is lowered in the same proportion, but the differential effect upon the eye is thereby augmented, and the bands are consequently more clearly seen. ( .) on friday, the th of july, we commenced our measurements. through the kindness of sir roderick murchison, i found myself in the possession of an excellent five-inch theodolite, an instrument with the use of which both my friend hirst and myself were perfectly familiar. we worked in concert for a few days to familiarize our assistant with the mode of proceeding, but afterwards it was my custom to simply determine the position where a measurement was to be made, and to leave the execution of it entirely to mr. hirst and our guide. on the th of july i made a long excursion up the glacier, examining the moraines, the crevasses, the structure, the moulins, and the disintegration of the surface. i was accompanied by a boy named edouard balmat,[a] and found him so good an iceman that i was induced to take him with me on the following day also. [sidenote: the cleft station. .] looking upwards from the montanvert to the left of the aiguille de charmoz, a singular gap is observed in the rocky mountain wall, in the centre of which stands a detached column of granite. both cleft and pillar are shown in the frontispiece, to the right. the eminence to the left of this gap is signalised by professor forbes as one of the best stations from which to view the mer de glace, and this point, which i shall refer to hereafter as the _cleft station_, it was now my desire to attain. from the montanvert side a steep gully leads to the cleft; up this couloir we proposed to try the ascent. at a considerable height above the mer de glace, and closely hugging the base of the aiguille de charmoz, is the small glacier de tendue, shown in the frontispiece, and from which a steep slope stretches down to the mer de glace. this tendue is the most _talkative_ glacier i have ever known; the clatter of the small stones which fall from it is incessant. huge masses of granite also frequently fall upon the glacier from the cliffs above it, and, being slowly borne downwards by the moving ice, are at length seen toppling above the terminal face of the glacier. the ice which supports them being gradually melted, they are at length undermined, and sent bounding down the slope with peal and rattle, according as the masses among which they move are large or small. the space beneath the glacier is cumbered with blocks thus sent down; some of them of enormous size. [sidenote: rough ascent. .] the danger arising from this intermittent cannonade, though in reality small, has caused the guides to swerve from the path which formerly led across the slope to the promontory of trélaporte. i say "small," because, even should a rock choose the precise moment at which a traveller is passing to leap down, the boulders at hand are so large and so capable of bearing a shock that the least presence of mind would be sufficient to place him in safety. but presence of mind is not to be calculated on under such circumstances, and hence the guides were right to abandon the path. reaching the mouth of our gully after a rough ascent, we took to the snow, instead of climbing the adjacent rocks. it was moist and soft, in fact in a condition altogether favourable for the "regelation" of its granules. as the foot pressed upon it the particles became cemented together. a portion of the pressure was transmitted laterally, which produced attachments beyond the boundary of the foot; thus as the latter sank, it pressed upon a surface which became continually wider and more rigid, and at length sufficiently strong to bear the entire weight of the body; the pressed snow formed in fact a virtual _camel's foot_, which soon placed a limit to the sinking. it is this same principle of regelation which enables men to cross snow bridges in safety. by gentle cautious pressure the loose granules of the substance are cemented into a continuous mass, all sudden shocks which might cause the frozen surfaces to snap asunder being avoided. in this way an arch of snow fifteen or twenty inches in thickness may be rendered so firm that a man will cross it, although it may span a chasm one hundred feet in depth. as we ascended, the incline became very steep, and once or twice we diverged from the snow to the adjacent rocks; these were disintegrated, and the slightest disturbance was sufficient to bring them down; some fell, and from one of them i found it a little difficult to escape; for it grazed my leg, inflicting a slight wound as it passed. just before reaching the cleft at which we aimed, the snow for a short distance was exceedingly steep, but we surmounted it; and i sat for a time beside the granite pillar, pleased to find that i could permit my legs to dangle over a precipice without prejudice to my head. [sidenote: chamois on the mountains. .] while we remained here a chamois made its appearance upon the rocks above us. deeming itself too near, it climbed higher, and then turned round to watch us. it was soon joined by a second, and the two formed a very pretty picture: their attitudes frequently changed, but they were always graceful; with head erect and horns curved back, a light limb thrown forward upon a ledge of rock, looking towards us with wild and earnest gaze, each seemed a type of freedom and agility. turning now to the left, we attacked the granite tower, from which we purposed to scan the glacier, and were soon upon its top. my companion was greatly pleased--he was "très-content" to have reached the place--he felt assured that many old guides would have retreated from that ugly gully, with its shifting shingle and débris, and his elation reached its climax in the declaration that, if i resolved to ascend mont blanc without a guide, he was willing to accompany me. [sidenote: scene from the station. .] from the position which we had attained, the prospect was exceedingly fine, both of the glaciers and of the mountains. beside us was the aiguille de charmoz, piercing with its spikes of granite the clear air. to my mind it is one of the finest of the aiguilles, noble in mass, with its summits singularly cleft and splintered. in some atmospheric colourings it has the exact appearance of a mountain of cast copper, and the manner in which some of its highest pinnacles are bent, suggesting the idea of ductility, gives strength to the illusion that the mass is metallic. at the opposite side of the glacier was the aiguille verte, with a cloud poised upon its point: it has long been the ambition of climbers to scale this peak, and on this day it was attempted by a young french count with a long retinue of guides. he had not fair play, for before we quitted our position we heard the rumble of thunder upon the mountain, which indicated the presence of a foe more terrible than the avalanches themselves. higher to the right, and also at the opposite side of the glacier, rose the aiguille du moine; and beyond was the basin of the talèfre, the ice cascade issuing from which appeared, from our position, like the foam of a waterfall. then came the aiguille de léchaud, the petite jorasse, the grande jorasse, and the mont tacul; all of which form a cradle for the glacier de léchaud. mont mallet, the périades, and the aiguille noire, came next, and then the singular obelisk of the aiguille du géant, from which a serrated edge of cliff descends to the summit of the "col." [sidenote: sÉracs of the col du gÉant. .] over the slopes of the col du géant was spread a coverlet of shining snow, at some places apparently as smooth as polished marble, at others broken so as to form precipices, on the pale blue faces of which the horizontal lines of bedding were beautifully drawn. as the eye approaches the line which stretches from the rognon to the aiguille noire, the repose of the _névé_ becomes more and more disturbed. vast chasms are formed, which however are still merely indicative of the trouble in advance. if the glacier were lifted off we should probably see that the line just referred to would lie along the summit of a steep gorge; over this summit the glacier is pushed, and has its back periodically broken, thus forming vast transverse ridges which follow each other in succession down the slope. at the summit these ridges are often cleft by fissures transverse to them, thus forming detached towers of ice of the most picturesque and imposing character.[b] these towers often fall; and while some are caught upon the platforms of the cascade, others struggle with the slow energy of a behemoth through the débris which opposes them, reach the edges of the precipices which rise in succession along the fall, leap over, and, amid ice-smoke and thunder-peals, fight their way downwards. [sidenote: glacier motion. .] a great number of secondary glaciers were in sight hanging on the steep slopes of the mountains, and from them streams sped downwards, falling over the rocks, and filling the valley with a low rich music. in front of me, for example, was the glacier du moine, and i could not help feeling as i looked at it, that the arguments drawn from the deportment of such glaciers against the "sliding theory," and which are still repeated in works upon the alps, militate just as strongly against the "viscous theory." "how," demands the antagonist of the sliding theory, "can a secondary glacier exist upon so steep a slope? why does it not slide down as an avalanche?" "but how," the person addressed may retort, "can a mass which you assume to be viscous exist under similar conditions? if it be viscous, what prevents it from rolling down?" the sliding theory assumes the lubrication of the bed of the glacier, but on this cold height the quantity melted is too small to lubricate the bed, and hence the slow motion of these glaciers. thus a sliding-theory man might reason, and, if the external deportment of secondary glaciers were to decide the question, de saussure might perhaps have the best of the argument. and with regard to the current idea, originated by m. de charpentier, and adopted by professor forbes, that if a glacier slides it must slide as an avalanche, it may be simply retorted that, in part, _it does so_; but if it be asserted that an _accelerated motion_ is the necessary motion of an avalanche, the statement needs qualification. an avalanche on passing through a rough couloir soon attains a uniform velocity--its motion being accelerated only up to the point when the sum of the resistances acting upon it is equal to the force drawing it downwards. these resistances are furnished by the numberless asperities which the mass encounters, and which incessantly check its descent, and render an accumulation of motion impossible. the motion of a man walking down stairs may be on the whole uniform, but it is really made up of an aggregate of small motions, each of which is accelerated; and it is easy to conceive how a glacier moving over an uneven bed, when released from one opposing obstacle will be checked by another, and its motion thus rendered sensibly uniform. [sidenote: moraines. .] [sidenote: tributaries of the mer de glace. .] [illustration: fig. . tributaries of the mer de glace.] from the aiguille du géant and les périades a glacier descended, which was separated by the promontory of la noire from the glacier proceeding from the col du géant. a small moraine was formed between them, which is marked _a_ upon the diagram, fig. . the great mass of the glacier descending from the col du géant came next, and this was bounded on the side nearest to trélaporte by a small moraine _b_, the origin of which i could not see, its upper portion being shut out by a mountain promontory. between the moraine _b_ and the actual side of the valley was another little glacier, derived from some of the lateral tributaries. it was, however, between the moraines _a_ and _b_ that the great mass of the glacier du géant really lay. at the promontory of the tacul the lateral moraines of the glacier des périades and of the glacier de léchaud united to form the medial moraine _c_ of the mer de glace. carrying the eye across the léchaud, we had the moraine _d_ formed by the union of the lateral moraines of the léchaud and talèfre; further to the left was the moraine _e_, which came from the jardin, and beyond it was the second lateral moraine of the talèfre. the mer de glace is formed by the confluence of the whole of the glaciers here named; being forced at trélaporte through a passage, the width of which appears considerably less than that of the single tributary, the glacier du géant. in the ice near trélaporte the blue veins of the glacier are beautifully shown; but they vary in distinctness according to the manner in which they are looked at. when regarded obliquely their colour is not so pronounced as when the vision plunges deeply into them. the weathered ice of the surface near trélaporte could be cloven with great facility; i could with ease obtain plates of it a quarter of an inch thick, and possessing two square feet of surface. on the th of july i followed the veins several times from side to side across the géant portion of the mer de glace; starting from one side, and walking along the veins, my route was directed obliquely downwards towards the axis of the tributary. at the axis i was forced to turn, in order to keep along the veins, and now ascended along a line which formed nearly the same angle with the axis at the other side. thus the veins led me as it were along the two sides of a triangle, the vertex of which was near the centre of the glacier. the vertex was, however, in reality rounded off, and the figure rather resembled a hyperbola, which tended to coincidence with its asymptotes. this observation corroborates those of professor forbes with regard to the position of the veins, and, like him, i found that at the centre the veining, whose normal direction would be transverse to the glacier, was contorted and confused. [sidenote: wasting of ice. .] near the side of the glacier du géant, above the promontory of trélaporte, the ice is rent in a remarkable manner. looking upwards from the lower portions of the glacier, a series of vertical walls, rising apparently one above the other, face the observer. i clambered up among these singular terraces, and now recognise, both from my sketch and memory, that their peculiar forms are due to the same action as that which has given their shape to the "billows" of the mer de glace. a series of profound crevasses is first formed. the glacier du géant deviates ° from the meridian line, and hence the sun shines nearly down it during the middle portion of each day. the backs of the ridges between the crevasses are thus rounded off, one boundary of each fissure is destroyed, or at least becomes a mere steep declivity, while the other boundary being shaded from the sun preserves its verticality; and thus a very curious series of precipices is formed. through all this dislocation, the little moraine on which i have placed the letter _b_ in the sketch maintains its right to existence, and under it the laminated structure of this portion of the glacier appears to reach its most perfect development. the moraine was generally a mere dirt track, but one or two immense blocks of granite were perched upon it. i examined the ice underneath one of these, being desirous of seeing whether the pressure resulting from its enormous weight would produce a veining, but the result was not satisfactory. veins were certainly to be seen in directions different from the normal ones, but whether they were due to the bending of the latter, or were directly owing to the pressure of the block, i could not say. the sides of a stream which had cut a deep gorge in the clean ice of the glacier du géant afforded a fine opportunity of observing the structure. it was very remarkable--highly significant indeed in a theoretic point of view. two long and remarkably deep blue veins traversed the bottom of the stream, and bending upwards at a place where the rivulet curved, drew themselves like a pair of parallel lines upon the clean white ice. but the general structure was of a totally different character; it did not consist of long bars, but approximated to the lenticular form, and was, moreover, of a washy paleness, which scarcely exceeded in depth of colouring the whitish ice around. [sidenote: grooves on the surface. .] to the investigator of the structure nothing can be finer than the appearance of the glacier from one of the ice terraces cut in the glacier du géant by its passage round trélaporte. as far as the vision extended the dirt upon the surface of the ice was arranged in striæ. these striæ were not always straight lines, nor were they unbroken curves. within slight limits the various parts into which a glacier is cut up by its crevasses enjoy a kind of independent motion. the grooves, for example, on two ridges which have been separated by a small fissure, may one day have their striæ perfect continuations of each other, but in a short time this identity of direction may be destroyed by a difference of motion between the ridges. thus it is that the grooves upon the surface above trélaporte are bent hither and thither, a crack or seam always marking the point where their continuity is ruptured. this bending occurs, however, within limits sufficiently small to enable the striæ to preserve the same general direction. [sidenote: seams of white ice. .] my attention had often been attracted this day by projecting masses of what at first appeared to be pure white snow, rising in seams above the general surface of the glacier. on examination, however, i found them to be compact ice, filled with innumerable air-cells, and so resistant as to maintain itself in some places at a height of four feet above the general level. when amongst the ridges they appeared discontinuous and confused, being scattered apparently at random over the glacier; but when viewed from a sufficient distance, the detached parts showed themselves to belong to a system of white seams which swept quite across the glacier du géant, in a direction concentric with the structure. unable to account for these singular seams, i climbed up among the tributary glaciers on the rognon side of the glacier du géant, and remained there until the sun sank behind the neighbouring peaks, and the fading light warned me that it was time to return. footnotes: [a] "le petit balmat" my host always called him. [b] to such towers the name _séracs_ is applied. in the chalets of savoy, after the richer curd has been precipitated by rennet, a stronger acid is used to throw down what remains; an inferior kind of cheese called _sérac_ is thus formed, the shape and colour of which have suggested the application of the term to the cubical masses of ice. ( .) early on the following day i was again upon the ice. i first confined myself to the right side of the glacier du géant, and found that the veins of white ice which i had noticed on the previous day were exclusively confined to this glacier, or to the space between the moraines _a_ and _b_ (fig. ), bending up so that the moraine _a_ between the glacier du géant and the glacier des périades was tangent to them. at a good distance up the glacier i encountered a considerable stream rushing across it almost from side to side. i followed the rivulet, examining the sections which it exposed. at a certain point three other streams united, and formed at their place of confluence a small green lake. from this a rivulet rushed, which was joined by the stream whose track i had pursued, and at this place of junction a second green lake was formed, from which flowed a stream equal in volume to the sum of all the tributaries. it entered a crevasse, and took the bottom of the fissure for its bed. standing at the entrance of the chasm, a low muffled thunder resounding through the valley attracted my attention. i followed the crevasse, which deepened and narrowed, and, by the blue light of the ice, could see the stream gambolling along its bottom, and flashing as it jumped over the ledges which it encountered in its way. the fissure at length came to an end: placing a foot on each side of it, and withholding the stronger light from my eyes, i looked down between its shining walls, and saw the stream plunge into a shaft which carried it to the bottom of the glacier. slowly, and in zigzag fashion, as the crevasses demanded, i continued to ascend, sometimes climbing vast humps of ice from which good views of the surrounding glacier were obtained; sometimes hidden in the hollows between the humps, in which also green glacier tarns were often formed, very lonely and very beautiful. [sidenote: a lake set free. .] while standing beside one of these, and watching the moving clouds which it faithfully mirrored, i heard the sound of what appeared to be a descending avalanche, but the time of its continuance surprised me. looking through my opera-glass in the direction of the sound, i saw issuing from the end of a secondary glacier on the tacul side a torrent of what appeared to me to be stones and mud. i could see the stones and finer débris jumping down the declivities, and shaping themselves into singular cascades. the noise continued for a quarter of an hour, after which the torrent rapidly diminished, until, at length, the ordinary little stream due to the melting of the glacier alone remained. a subglacial lake had burst its boundary, and carried along with it in its rush downwards the débris which it met with in its course. [sidenote: impressive scene. .] in some places i found the crevasses difficult, the ice being split in a very singular manner. vast plates of it not more than a foot in thickness were sometimes detached from the sides of the crevasses, and stood alone. i was now approaching the base of the _séracs_, and the glacier around me still retained a portion of the turbulence of the cascade. i halted at times amid the ruin and confusion, and examined with my glass the cascade itself. it was a wild and wonderful scene, suggesting throes of spasmodic energy, though, in reality, all its dislocation had been _slowly_ and _gradually_ produced. true, the stratified blocks which here and there cumbered the terraces suggested _débacles_, but these were local and partial, and did not affect the general question. there is scarcely a case of geological disturbance which could not be matched with its analogue upon the glaciers,--contortions, faults, fissures, joints, and dislocations,--but in the case of the ice we can prove the effects to be due to slowly-acting causes; how reasonable is it then to ascribe to the operation of similar causes, which have had an incomparably longer time to work, many geological effects which at first sight might suggest sudden convulsion! wandering slowly upwards, successive points of attraction drawing me almost unconsciously on, i found myself as the day was declining deep in the entanglements of the ice. a shower commenced, and a splendid rainbow threw an oblique arch across the glacier. i was quite alone; the scene was exceedingly impressive, and the possibility of difficulties on which i had not calculated intervening between me and the lower glacier, gave a tinge of anxiety to my position. i turned towards home; crossed some bosses of ice and rounded others; i followed the tracks of streams which were very irregular on this portion of the glacier, bending hither and thither, rushing through deep-cut channels, falling in cascades and expanding here and there to deep green lakes; they often plunged into the depths of the ice, flowed under it with hollow gurgle, and reappeared at some distant point. i threaded my way cautiously amid systems of crevasses, scattering with my axe, to secure a footing, the rotten ice of the sharper crests, which fell with a ringing sound into the chasms at either side. strange subglacial noises were sometimes heard, as if caverns existed underneath, into which blocks of ice fell at intervals, transmitting the shock of their fall with a dull boom to the surface of the glacier. by the steady surmounting of difficulties one after another, i at length placed them all behind me, and afterwards hastened swiftly along the glacier to my mountain home. [sidenote: chamouni rules. .] on the th incessant rain confined us to indoor work; on the st we determined the velocity with which the glacier is forced through the entrance of the trunk valley at trélaporte, and also the motion of the grand moulin. we also determined both the velocity and the width of the glacier du géant. the st of august was spent by me at the cascade of the talèfre, examining the structure, crumpling, and scaling off of the ice. finding that the rules at chamouni put an unpleasant limit to my demands on my guide simond, i visited the guide chef on the nd of august, and explained to him the object of my expedition, pointing out the inconvenience which a rigid application of the rules made for tourists would impose upon me. he had then the good sense to acknowledge the reasonableness of my remarks, and to grant me the liberty i requested. the rd of august was employed in determining the velocity and width of the glacier de léchaud, and in observations on the lamination of the glacier. [sidenote: the jardin. .] the jardin. ( .) [sidenote: a reservoir of ice. .] on the th of august, with a view of commencing a series of observations on the inclinations of the mer de glace and its tributaries, we had our theodolite transported to the _jardin_, which, as is well known, lies like an island in the middle of the glacier du talèfre. we reached the place by the usual route, and found some tourists reposing on the soft green sward which covers the lower portion, and to which, and the flowers which spangle it, the place owes its name. towards the summit of the jardin, a rock jutted forward, apparently the very apex of the place, or at least hiding by its prominence everything that might exist behind it; leaving our guide with the instrument, we aimed at this, and soon left the grass and flowers behind us. stepping amid broken fragments of rock, along slopes of granite, with fat felspar crystals which gave the boots a hold, and crossing at intervals patches of snow, which continued still to challenge the summer heat, i at length found myself upon the peak referred to; and, although it was not the highest, the unimpeded view which it commanded induced me to get astride it. the jardin was completely encircled by the ice of the glacier, and this was held in a mountain basin, which was bounded all round by a grand and cliffy rim. the outline of the dark brown crags--a deeply serrated and irregular line--was forcibly drawn against the blue heaven, and still more strongly against some white and fleecy clouds which lay here and there behind it; while detached spears and pillars of rock, sculptured by frost and lightning, stood like a kind of defaced statuary along the ridge. all round the basin the snow reared itself like a buttress against the precipitous cliffs, being streaked and fluted by the descent of blocks from the summits. this mighty tub is the collector of one of the tributaries of the mer de glace. according to professor forbes, its greatest diameter is yards, and out of it the half-formed ice is squeezed through a precipitous gorge about yards wide, forming there the ice cascade of the talèfre. bounded on one side by the grande jorasse, and on the other by mont mallet, the principal tributary of the glacier de léchaud lay white and pure upon the mountain slope. round further to the right we had the vast plateau whence the glacier du géant is fed, fenced on the left by the aiguille du géant and the aiguille noire, and on the right by the monts maudits and mont blanc. the scene was a truly majestic one. the mighty aiguilles piercing the sea of air, the soft white clouds floating here and there behind them; the shining snow with its striped faults and precipices; the deep blue firmament overhead; the peals of avalanches and the sound of water;--all conspired to render the scene glorious, and our enjoyment of it deep. a voice from above hailed me as i moved from my perch; it was my friend, who had found a lodgment upon the edge of a rock which was quite detached from the jardin, being the first to lift its head in opposition to the descending _névé_. making a détour round a steep concave slope of the glacier, i reached the flat summit of the rock. the end of a ridge of ice abutted against it, which was split and bent by the pressure so as to form a kind of arch. i cut steps in the ice, and ascended until i got beneath the azure roof. innumerable little rills of pellucid water descended from it. some came straight down, clear for a time, and apparently motionless, rapidly tapering at first, and more slowly afterwards, until, at the point of maximum contraction, they resolved themselves into strings of liquid pearls which pattered against the ice floor underneath. others again, owing to the directions of the little streamlets of which they were constituted, formed spiral figures of great beauty: one liquid vein wound itself round another, forming a spiral protuberance, and owing to the centrifugal motion thus imparted, the vein, at its place of rupture, scattered itself laterally in little liquid spherules.[a] even at this great elevation the structure of the ice was fairly developed, not with the sharpness to be observed lower down, but still perfectly decided. blue bands crossed the ridge of ice to which i have referred, at right angles to the direction of the pressure. [sidenote: moraines of the talÈfre. .] i descended, and found my friend beneath an overhanging rock. immediately afterwards a peal like that of thunder shook the air, and right in front of us an avalanche darted down the brown cliffs, then along a steep slope of snow which reared itself against the mountain wall, carrying with it the débris of the rocks over which it passed, until it finally lay a mass of sullied rubbish at the base of the incline: the whole surface of the talèfre is thus soiled. another peal was heard immediately afterwards, but the avalanche which caused it was hidden from us by a rocky promontory. from this same promontory the greater portion of the medial moraine which descends the cascade of the talèfre is derived, forming at first a gracefully winding curve, and afterwards stretching straight to the summit of the fall. in the chasms of the cascade its boulders are engulfed, but the lost moraine is restored below the fall, as if disgorged by the ice which had swallowed it. from the extremity of the jardin itself a mere driblet of a moraine proceeds, running parallel to the former, and like it disappearing at the summit of the cascade. [sidenote: among the crevasses. .] we afterwards descended towards the cascade, but long before this is attained the most experienced iceman would find himself in difficulty. transverse crevasses are formed, which follow each other so speedily as to leave between them mere narrow ridges of ice, along which we moved cautiously, jumping the adjacent fissures, or getting round them, as the case demanded. as we approached the jaws of the gorge, the ridges dwindled to mere plates and wedges, which being bent and broken by the lateral pressure, added to the confusion, and warned us not to advance. the position was in some measure an exciting one. our guide had never been here before; we were far from the beaten track, and the riven glacier wore an aspect of treacherous hostility. as at the base of the _séracs_, a subterranean noise sometimes announced the falling of ice-blocks into hollows underneath, the existence of which the resonant concussion of the fallen mass alone revealed. there was thus a dash of awe mingled with our thoughts; a stirring up of the feelings which troubled the coolness of the intellect. we finally swerved to the right, and by a process the reverse of straightforward reached the couvercle. nightfall found us at the threshold of our hotel. footnotes: [a] the recent hydraulic researches of professor magnus furnish some beautiful illustrations of this action. ( .) [sidenote: round hailstones. .] [sidenote: a dangerous leap. .] on the th we were engaged for some time in an important measurement at the tacul. we afterwards ascended towards the _séracs_, and determined the inclinations of the glacier du géant downwards. dense cloud-masses gathered round the points of the aiguilles, and the thunder bellowed at intervals from the summit of mont blanc. as we descended the mer de glace the valley in front of us was filled with a cloud of pitchy darkness. suddenly from side to side this field of gloom was riven by a bar of lightning of intolerable splendour; it was followed by a peal of commensurate grandeur, the echoes of which leaped from cliff to cliff long after the first sound had died away. the discharge seemed to unlock the clouds above us, for they showered their liquid spheres down upon us with a momentum like that of swan-shot: all the way home we were battered by this pellet-like rain. on the th the rain continued with scarcely any pause; on the th i was engaged all day upon the glacier du géant; on the morning of the th heavy hail had fallen there, the stones being perfect spheres; the rounded rain-drops had solidified during their descent without sensible change of form. when this hail was squeezed together, it exactly resembled a mass of oolitic limestone which i had picked up in near blankenburg in the hartz. mr. hirst and myself were engaged together this day taking the inclinations: he struck his theodolite at the angle, and went home accompanied by simond, and the evening being extremely serene, i pursued my way down the centre of the glacier towards the echelets. the crevasses as i advanced became more deep and frequent, the ridges of ice between them becoming gradually narrower. they were very fine, their downward faces being clear cut, perfectly vertical, and in many cases beautifully veined. vast plates of ice moreover often stood out midway between the walls of the chasms, as if cloven from the glacier and afterwards set on edge. the place was certainly one calculated to test the skill and nerve of an iceman; and as the day drooped, and the shadow in the valley deepened, a feeling approaching to awe took possession of me. my route was an exaggerated zigzag; right and left amid the chasms wherever a hope of progress opened; and here i made the experience which i have often repeated since, and laid to heart as regards intellectual work also, that enormous difficulties may be overcome when they are attacked in earnest. sometimes i found myself so hedged in by fissures that escape seemed absolutely impossible; but close and resolute examination so often revealed a means of exit, that i felt in all its force the brave verity of the remark of mirabeau, that the word "impossible" is a mere blockhead of a word. it finally became necessary to reach the shore, but i found this a work of extreme difficulty. at length, however, it became pretty evident that, if i could cross a certain crevasse, my retreat would be secured. the width of the fissure seemed to be fairly within jumping distance, and if i could have calculated on a safe purchase for my foot i should have thought little of the spring; but the ice on the edge from which i was to leap was loose and insecure, and hence a kind of nervous thrill shot through me as i made the bound. the opposite side was fairly reached, but an involuntary tremor shook me all over after i felt myself secure. i reached the edge of the glacier without further serious difficulty, and soon after found myself steeped in the creature comforts of our hotel. on monday, august th, i had the great pleasure of being joined by my friend huxley; and though the weather was very unpromising, we started together up the glacier, he being desirous to learn something of its general features, and, if possible, to reach the jardin. we reached the couvercle, and squeezed ourselves through the egralets; but here the rain whizzed past us, and dense fog settled upon the cascade of the talèfre, obscuring all its parts. we met mr. galton, the african traveller, returning from an attempt upon the jardin; and learning that his guides had lost their way in the fog, we deemed it prudent to return. the foregoing brief notes will have informed the reader that at the period of mr. huxley's arrival i was not without due training upon the ice; i may also remark, that on the th of july i reached the summit of the col du géant, accompanied by the boy balmat, and returned to the montanvert on the same day. my health was perfect, and incessant practice had taught me the art of dealing with the difficulties of the ice. from the time of my arrival at the montanvert the thought of ascending mont blanc, and thus expanding my knowledge of the glaciers, had often occurred to me, and i think i was justified in feeling that the discipline which both my friend hirst and myself had undergone ought to enable us to accomplish the journey in a much more modest way than ordinary. i thought a single guide sufficient for this purpose, and i was strengthened in this opinion by the fact that simond, who was a man of the strictest prudence, and who at first declared four guides to be necessary, had lowered his demand first to two, and was now evidently willing to try the ascent with us alone. [sidenote: preparations for a climb. .] on mentioning the thing to mr. huxley he at once resolved to accompany us. on the th of august the weather was exceedingly fine, though the snow which had fallen during the previous days lay thick upon the glacier. at noon we were all together at the tacul, and the subject of attempting mont blanc was mooted and discussed. my opinion was that it would be better to wait until the fresh snow which loaded the mountain had disappeared; but the weather was so exquisite that my friends thought it best to take advantage of it. we accordingly entered into an agreement with our guide, and immediately descended to make preparations for commencing the expedition on the following morning. first ascent of mont blanc, . ( .) [sidenote: scene from the charmoz. .] on wednesday, the th of august, we rose early, after a very brief rest on my part. simond had proposed to go down to chamouni, and commence the ascent in the usual way, but we preferred crossing the mountains from the montanvert, straight to the glacier des bossons. at eight o'clock we started, accompanied by two porters who were to carry our provisions to the grands mulets. slowly and silently we climbed the hill-side towards charmoz. we soon passed the limits of grass and rhododendrons, and reached the slabs of gneiss which overspread the summit of the ridge, lying one upon the other like coin upon the table of a money-changer. from the highest-point i turned to have a last look at the mer de glace; and through a pair of very dark spectacles i could see with perfect distinctness the looped dirt-bands of the glacier, which to the naked eye are scarcely discernible except by twilight. flanking our track to the left rose a series of mighty aiguilles--the aiguille de charmoz, with its bent and rifted pinnacles; the aiguille du grépon, the aiguille de blaitière, the aiguille du midi, all piercing the heavens with their sharp pyramidal summits. far in front of us rose the grand snow-cone of the dôme du goûter, while, through a forest of dark pines which gathered like a cloud at the foot of the mountain, gleamed the white minarets of the glacier des bossons. below us lay the valley of chamouni, beyond which were the brévent and the chain of the aiguilles rouges; behind us was the granite obelisk of the aiguille du dru, while close at hand science found a corporeal form in a pyramid of stones used as a trigonometrical station by professor forbes. sound is known to travel better up hill than down, because the pulses transmitted from a denser medium to a rarer, suffer less loss of intensity than when the transmission is in the opposite direction; and now the mellow voice of the arve came swinging upwards from the heavier air of the valley to the lighter air of the hills in rich deep cadences. [sidenote: passage to the pierre À l'echelle. .] the way for a time was excessively rough, our route being overspread with the fragments of peaks which had once reared themselves to our left, but which frost and lightning had shaken to pieces, and poured in granite avalanches down the mountain. we were sometimes among huge angular boulders, and sometimes amid lighter shingle, which gave way at every step, thus forcing us to shift our footing incessantly. escaping from these, we crossed the succession of secondary glaciers which lie at the feet of the aiguilles, and having secured firewood found ourselves after some hours of hard work at the pierre à l'echelle. here we were furnished with leggings of coarse woollen cloth to keep out the snow; they were tied under the knees and quite tightly again over the insteps, so that the legs were effectually protected. we had some refreshment, possessed ourselves of the ladder, and entered upon the glacier. [sidenote: ladder left behind. .] [sidenote: difficult crevasses. .] the ice was excessively fissured: we crossed crevasses and crept round slippery ridges, cutting steps in the ice wherever climbing was necessary. this rendered our progress very slow. once, with the intention of lending a helping hand, i stepped forward upon a block of granite which happened to be poised like a rocking stone upon the ice, though i did not know it; it treacherously turned under me; i fell, but my hands were in instant requisition, and i escaped with a bruise, from which, however, the blood oozed angrily. we found the ladder necessary in crossing some of the chasms, the iron spikes at its end being firmly driven into the ice at one side, while the other end rested on the opposite side of the fissure. the middle portion of the glacier was not difficult. mounds of ice rose beside us right and left, which were sometimes split into high towers and gaunt-looking pyramids, while the space between was unbroken. twenty minutes' walking brought us again to a fissured portion of the glacier, and here our porter left the ladder on the ice behind him. for some time i was not aware of this, but we were soon fronted by a chasm to pass which we were in consequence compelled to make a long and dangerous circuit amid crests of crumbling ice. this accomplished, we hoped that no repetition of the process would occur, but we speedily came to a second fissure, where it was necessary to step from a projecting end of ice to a mass of soft snow which overhung the opposite side. simond could reach this snow with his long-handled axe; he beat it down to give it rigidity, but it was exceedingly tender, and as he worked at it he continued to express his fears that it would not bear us. i was the lightest of the party, and therefore tested the passage, first; being partially lifted by simond on the end of his axe, i crossed the fissure, obtained some anchorage at the other side, and helped the others over. we afterwards ascended until another chasm, deeper and wider than any we had hitherto encountered, arrested us. we walked alongside of it in search of a snow bridge, which we at length found, but the keystone of the arch had unfortunately given way, leaving projecting eaves of snow at both sides, between which we could look into the gulf, till the gloom of its deeper portions cut the vision short. both sides of the crevasse were sounded, but no sure footing was obtained; the snow was beaten and carefully trodden down as near to the edge as possible, but it finally broke away from the foot and fell into the chasm. one of our porters was short-legged and a bad iceman; the other was a daring fellow, and he now threw the knapsack from his shoulders, came to the edge of the crevasse, looked into it, but drew back again. after a pause he repeated the act, testing the snow with his feet and staff. i looked at the man as he stood beside the chasm manifestly undecided as to whether he should take the step upon which his life would hang, and thought it advisable to put a stop to such perilous play. i accordingly interposed, the man withdrew from the crevasse, and he and simond descended to fetch the ladder. while they were away huxley sat down upon the ice, with an expression of fatigue stamped upon his countenance: the spirit and the muscles were evidently at war, and the resolute will mixed itself strangely with the sense of peril and feeling of exhaustion. he had been only two days with us, and, though his strength is great, he had had no opportunity of hardening himself by previous exercise upon the ice for the task which he had undertaken. the ladder now arrived, and we crossed the crevasse. i was intentionally the last of the party, huxley being immediately in front of me. the determination of the man disguised his real condition from everybody but myself, but i saw that the exhausting journey over the boulders and débris had been too much for his london limbs. converting my waterproof haversack into a cushion, i made him sit down upon it at intervals, and by thus breaking the steep ascent into short stages we reached the cabin of the grands mulets together. here i spread a rug on the boards, and placing my bag for a pillow, he lay down, and after an hour's profound sleep he rose refreshed and well; but still he thought it wise not to attempt the ascent farther. our porters left us: a bâton was stretched across the room over the stove, and our wet socks and leggings were thrown across it to dry; our boots were placed around the fire, and we set about preparing our evening meal. a pan was placed upon the fire, and filled with snow, which in due time melted and boiled; i ground some chocolate and placed it in the pan, and afterwards ladled the beverage into the vessels we possessed, which consisted of two earthen dishes and the metal cases of our brandy flasks. after supper simond went out to inspect the glacier, and was observed by huxley, as twilight fell, in a state of deep contemplation beside a crevasse. [sidenote: star twinkling. .] gradually the stars appeared, but as yet no moon. before lying down we went out to look at the firmament, and noticed, what i suppose has been observed to some extent by everybody, that the stars near the horizon twinkled busily, while those near the zenith shone with a steady light. one large star in particular excited our admiration; it flashed intensely, and changed colour incessantly, sometimes blushing like a ruby, and again gleaming like an emerald. a determinate colour would sometimes remain constant for a sensible time, but usually the flashes followed each other in very quick succession. three planks were now placed across the room near the stove, and upon these, with their rugs folded round them, huxley and hirst stretched themselves, while i nestled on the boards at the most distant end of the room. we rose at eleven o'clock, renewed the fire and warmed ourselves, after which we lay down again. i at length observed a patch of pale light upon the wooden wall of the cabin, which had entered through a hole in the end of the edifice, and rising found that it was past one o'clock. the cloudless moon was shining over the wastes of snow, and the scene outside was at once wild, grand, and beautiful. [sidenote: start from the grands mulets. .] breakfast was soon prepared, though not without difficulty; we had no candles, they had been forgotten; but i fortunately possessed a box of wax matches, of which huxley took charge, patiently igniting them in succession, and thus giving us a tolerably continuous light. we had some tea, which had been made at the montanvert, and carried to the grands mulets in a bottle. my memory of that tea is not pleasant; it had been left a whole night in contact with its leaves, and smacked strongly of tannin. the snow-water, moreover, with which we diluted it was not pure, but left a black residuum at the bottom of the dishes in which the beverage was served. the few provisions deemed necessary being placed in simond's knapsack, at twenty minutes past two o'clock we scrambled down the rocks, leaving huxley behind us. the snow was hardened by the night's frost, and we were cheered by the hope of being able to accomplish the ascent with comparatively little labour. we were environed by an atmosphere of perfect purity; the larger stars hung like gems above us, and the moon, about half full, shone with wondrous radiance in the dark firmament. one star in particular, which lay eastward from the moon, suddenly made its appearance above one of the aiguilles, and burned there with unspeakable splendour. we turned once towards the mulets, and saw huxley's form projected against the sky as he stood upon a pinnacle of rock; he gave us a last wave of the hand and descended, while we receded from him into the solitudes. the evening previous our guide had examined the glacier for some distance, his progress having been arrested by a crevasse. beside this we soon halted: it was spanned at one place by a bridge of snow, which was of too light a structure to permit of simond's testing it alone; we therefore paused while our guide uncoiled a rope and tied us all together. the moment was to me a peculiarly solemn one. our little party seemed so lonely and so small amid the silence and the vastness of the surrounding scene. we were about to try our strength under unknown conditions, and as the various possibilities of the enterprise crowded on the imagination, a sense of responsibility for a moment oppressed me. but as i looked aloft and saw the glory of the heavens, my heart lightened, and i remarked cheerily to hirst that nature seemed to smile upon our work. "yes," he replied, in a calm and earnest voice, "and, god willing, we shall accomplish it." [sidenote: a wrong turn. .] a pale light now overspread the eastern sky, which increased, as we ascended, to a daffodil tinge; this afterwards heightened to orange, deepening at one extremity into red, and fading at the other into a pure ethereal hue to which it would be difficult to assign a special name. higher up the sky was violet, and this changed by insensible degrees into the darkling blue of the zenith, which had to thank the light of moon and stars alone for its existence. we wound steadily for a time through valleys of ice, climbed white and slippery slopes, crossed a number of crevasses, and after some time found ourselves beside a chasm of great depth and width, which extended right and left as far as we could see. we turned to the left, and marched along its edge in search of a _pont_; but matters became gradually worse: other crevasses joined on to the first one, and the further we proceeded the more riven and dislocated the ice became. at length we reached a place where further advance was impossible. simond in his difficulty complained of the want of light, and wished us to wait for the advancing day; i, on the contrary, thought that we had light enough and ought to make use of it. here the thought occurred to me that simond, having been only once before to the top of the mountain, might not be quite clear about the route; the glacier, however, changes within certain limits from year to year, so that a general knowledge was all that could be expected, and we trusted to our own muscles to make good any mistake in the way of guidance. we now turned and retraced our steps along the edges of chasms where the ice was disintegrated and insecure, and succeeded at length in finding a bridge which bore us across the crevasse. this error caused us the loss of an hour, and after walking for this time we could cast a stone from the point we had attained to the place whence we had been compelled to return. [sidenote: sÉracs of the dÔme du goÛter. .] our way now lay along the face of a steep incline of snow, which was cut by the fissure we had just passed, in a direction parallel to our route. on the heights to our right, loose ice-crags seemed to totter, and we passed two tracks over which the frozen blocks had rushed some short time previously. we were glad to get out of the range of these terrible projectiles, and still more so to escape the vicinity of that ugly crevasse. to be killed in the open air would be a luxury, compared with having the life squeezed out of one in the horrible gloom of these chasms. the blush of the coming day became more and more intense; still the sun himself did not appear, being hidden from us by the peaks of the aiguille du midi, which were drawn clear and sharp against the brightening sky. right under this aiguille were heaps of snow smoothly rounded and constituting a portion of the sources whence the glacier du géant is fed; these, as the day advanced, bloomed with a rosy light. we reached the petit plateau, which we found covered with the remains of ice avalanches; above us upon the crest of the mountain rose three mighty bastions, divided from each other by deep vertical rents, with clean smooth walls, across which the lines of annual bedding were drawn like courses of masonry. from these, which incessantly renew themselves, and from the loose and broken ice-crags near them, the boulders amid which we now threaded our way had been discharged. when they fall their descent must be sublime. [sidenote: the lost guides. .] the snow had been gradually getting deeper, and the ascent more wearisome, but superadded to this at the petit plateau was the uncertainty of the footing between the blocks of ice. in many places the space was merely covered by a thin crust, which, when trod upon, instantly yielded, and we sank with a shock sometimes to the hips. our way next lay up a steep incline to the grand plateau, the depth and tenderness of the snow augmenting as we ascended. we had not yet seen the sun, but, as we attained the brow which forms the entrance to the grand plateau, he hung his disk upon a spike of rock to our left, and, surrounded by a glory of interference spectra of the most gorgeous colours, blazed down upon us. on the grand plateau we halted and had our frugal refreshment. at some distance to our left was the crevasse into which dr. hamel's three guides were precipitated by an avalanche in ; they are still entombed in the ice, and some future explorer may perhaps see them disgorged lower down, fresh and undecayed. they can hardly reach the surface until they pass the snow-line of the glacier, for above this line the quantity of snow that annually falls being in excess of the quantity melted, the tendency would be to make the ice-covering above them thicker. but it is also possible that the waste of the ice underneath may have brought the bodies to the bed of the glacier, where their very bones may have been ground to mud by an agency which the hardest rocks cannot withstand. [sidenote: the guide tired. .] [sidenote: a perilous slope. .] as the sun poured his light upon the plateau the little snow-facets sparkled brilliantly, sometimes with a pure white light, and at others with prismatic colours. contrasted with the white spaces above and around us were the dark mountains on the opposite side of the valley of chamouni, around which fantastic masses of cloud were beginning to build themselves. mont buet, with its cone of snow, looked small, and the brévent altogether mean; the limestone bastions of the fys, however, still presented a front of gloom and grandeur. we traversed the grand plateau, and at length reached the base of an extremely steep incline which stretched upwards towards the corridor. here, as if produced by a fault, consequent upon the sinking of the ice in front, rose a vertical precipice, from the coping of which vast stalactites of ice depended. previous to reaching this place i had noticed a haggard expression upon the countenance of our guide, which was now intensified by the prospect of the ascent before him. hitherto he had always been in front, which was certainly the most fatiguing position. i felt that i must now take the lead, so i spoke cheerily to the man and placed him behind me. marking a number of points upon the slope as resting places, i went swiftly from one to the other. the surface of the snow had been partially melted by the sun and then refrozen, thus forming a superficial crust, which bore the weight up to a certain point, and then suddenly gave way, permitting the leg to sink to above the knee. the shock consequent on this, and the subsequent effort necessary to extricate the leg, were extremely fatiguing. my motion was complained of as too quick, and my tracks as imperfect; i moderated the former, and, to render my footholes broad and sure, i stamped upon the frozen crust, and twisted my legs in the soft mass underneath,--a terribly exhausting process. i thus led the way to the base of the rochers rouges, up to which the fault already referred to had prolonged itself as a crevasse, which was roofed at one place by a most dangerous-looking snow-bridge. simond came to the front; i drew his attention to the state of the snow, and proposed climbing the rochers rouges; but, with a promptness unusual with him, he replied that this was impossible; the bridge was our only means of passing, and we must try it. we grasped our ropes, and dug our feet firmly into the snow to check the man's descent if the _pont_ gave way, but to our astonishment it bore him, and bore us safely after him. the slope which we had now to ascend had the snow swept from its surface, and was therefore firm ice. it was most dangerously steep, and, its termination being the fretted coping of the precipice to which i have referred, if we slid downwards we should shoot over this and be dashed to pieces upon the ice below.[a] simond, who had come to the front to cross the crevasse, was now engaged in cutting steps, which he made deep and large, so that they might serve us on our return. but the listless strokes of his axe proclaimed his exhaustion; so i took the implement out of his hands, and changed places with him. step after step was hewn, but the top of the corridor appeared ever to recede from us. hirst was behind unoccupied, and could thus turn his thoughts to the peril of our position: he _felt_ the angle on which we hung, and saw the edge of the precipice, to which less than a quarter of a minute's slide would carry us, and for the first time during the journey he grew giddy. a cigar which he lighted for the purpose tranquilized him. [sidenote: will and muscle. .] i hewed sixty steps upon this slope, and each step had cost a minute, by hirst's watch. the mur de la côte was still before us, and on this the guide-books informed us two or three hundred steps were sometimes found necessary. if sixty steps cost an hour, what would be the cost of two hundred? the question was disheartening in the extreme, for the time at which we had calculated on reaching the summit was already passed, while the chief difficulties remained unconquered. having hewn our way along the harder ice we reached snow. i again resorted to stamping to secure a footing, and while thus engaged became, for the first time, aware of the drain of force to which i was subjecting myself. the thought of being absolutely exhausted had never occurred to me, and from first to last i had taken no care to husband my strength. i always calculated that the _will_ would serve me even should the muscles fail, but i now found that mechanical laws rule man in the long run; that no effort of will, no power of spirit, can draw beyond a certain limit upon muscular force. the soul, it is true, can stir the body to action, but its function is to excite and apply force, and not to create it. while stamping forward through the frozen crust i was compelled to pause at short intervals; then would set out again apparently fresh, to find, however, in a few minutes that my strength was gone, and that i required to rest once more. in this way i gained the summit of the corridor, when hirst came to the front, and i felt some relief in stepping slowly after him, making use of the holes into which his feet had sunk. he thus led the way to the base of the mur de la côte, the thought of which had so long cast a gloom upon us; here we left our rope behind us, and while pausing i asked simond whether he did not feel a desire to go to the summit--"_bien sûr_," was his reply, "_mais!_" our guide's mind was so constituted that the "_mais_" seemed essential to its peace. i stretched my hand towards him, and said, "simond, we must do it." one thing alone i felt could defeat us: the usual time of the ascent had been more than doubled, the day was already far spent, and if the ascent would throw our subsequent descent into night it could not be contemplated. [sidenote: a doze on the calotte. .] we now faced the mur, which was by no means so bad as we had expected. driving the iron claws of our boots into the scars made by the axe, and the spikes of our bâtons into the slope above our feet, we ascended steadily until the summit was attained, and the top of the mountain rose clearly above us. we congratulated ourselves upon this; but simond, probably fearing that our joy might become too full, remarked, "_mais le sommet est encore bien loin!_" it was, alas! too true. the snow became soft again, and our weary limbs sank in it as before. our guide went on in front, audibly muttering his doubts as to our ability to reach the top, and at length he threw himself upon the snow, and exclaimed, "_il faut y renoncer!_" hirst now undertook the task of rekindling the guide's enthusiasm, after which simond rose, exclaiming, "_ah! comme ça me fait mal aux genoux_," and went forward. two rocks break through the snow between the summit of the mur and the top of the mountain; the first is called the petits mulets, and the highest the derniers rochers. at the former of these we paused to rest, and finished our scanty store of wine and provisions. we had not a bit of bread nor a drop of wine left; our brandy flasks were also nearly exhausted, and thus we had to contemplate the journey to the summit, and the subsequent descent to the grands mulets, without the slightest prospect of physical refreshment. the almost total loss of two nights' sleep, with two days' toil superadded, made me long for a few minutes' doze, so i stretched myself upon a composite couch of snow and granite, and immediately fell asleep. my friend, however, soon aroused me. "you quite frighten me," he said; "i have listened for some minutes, and have not heard you breathe once." i had, in reality, been taking deep draughts of the mountain air, but so silently as not to be heard. i now filled our empty wine-bottle with snow and placed it in the sunshine, that we might have a little water on our return. we then rose; it was half-past two o'clock; we had been upwards of twelve hours climbing, and i calculated that, whether we reached the summit or not, we could at all events work _towards_ it for another hour. to the sense of fatigue previously experienced, a new phenomenon was now added--the beating of the heart. we were incessantly pulled up by this, which sometimes became so intense as to suggest danger. i counted the number of paces which we were able to accomplish without resting, and found that at the end of every twenty, sometimes at the end of fifteen, we were compelled to pause. at each pause my heart throbbed audibly, as i leaned upon my staff, and the subsidence of this action was always the signal for further advance. my breathing was quick, but light and unimpeded. i endeavoured to ascertain whether the hip-joint, on account of the diminished atmospheric pressure, became loosened, so as to throw the weight of the leg upon the surrounding ligaments, but could not be certain about it. i also sought a little aid and encouragement from philosophy, endeavouring to remember what great things had been done by the accumulation of small quantities, and i urged upon myself that the present was a case in point, and that the summation of distances twenty paces each must finally place us at the top. still the question of time left the matter long in doubt, and until we had passed the derniers rochers we worked on with the stern indifference of men who were doing their duty, and did not look to consequences. here, however, a gleam of hope began to brighten our souls; the summit became visibly nearer, simond showed more alacrity; at length success became certain, and at half-past three p.m. my friend and i clasped hands upon the top. [sidenote: the summit attained. .] the summit of the mountain is an elongated ridge, which has been compared to the back of an ass. it was perfectly manifest that we were dominant over all other mountains; as far as the eye could range mont blanc had no competitor. the summits which had looked down upon us in the morning were now far beneath us. the dôme du goûter, which had held its threatening _séracs_ above us so long, was now at our feet. the aiguille du midi, mont blanc du tacul, and the monts maudits, the talèfre with its surrounding peaks, the grand jorasse, mont mallet, and the aiguille du géant, with our own familiar glaciers, were all below us. and as our eye ranged over the broad shoulders of the mountain, over ice hills and valleys, plateaux and far-stretching slopes of snow, the conception of its magnitude grew upon us, and impressed us more and more. [sidenote: clouds from the summit. .] the clouds were very grand--grander indeed than anything i had ever before seen. some of them seemed to hold thunder in their breasts, they were so dense and dark; others, with their faces turned sunward, shone with the dazzling whiteness of the mountain snow; while others again built themselves into forms resembling gigantic elm trees, loaded with foliage. towards the horizon the luxury of colour added itself to the magnificent alternations of light and shade. clear spaces of amber and ethereal green embraced the red and purple cumuli, and seemed to form the cradle in which they swung. closer at hand squally mists, suddenly engendered, were driven hither and thither by local winds; while the clouds at a distance lay "like angels sleeping on the wing," with scarcely visible motion. mingling with the clouds, and sometimes rising above them, were the highest mountain heads, and as our eyes wandered from peak to peak, onwards to the remote horizon, space itself seemed more vast from the manner in which the objects which it held were distributed. [sidenote: intensity of sound. .] i wished to repeat the remarkable experiment of de saussure upon sound, and for this purpose had requested simond to bring a pistol from chamouni; but in the multitude of his cares he forgot it, and in lieu of it my host at the montanvert had placed in two tin tubes, of the same size and shape, the same amount of gunpowder, securely closing the tubes afterwards, and furnishing each of them with a small lateral aperture. we now planted one of them upon the snow, and bringing a strip of amadou into communication with the touchhole, ignited its most distant end: it failed; we tried again, and were successful, the explosion tearing asunder the little case which contained the powder. the sound was certainly not so great as i should have expected from an equal quantity of powder at the sea level.[b] the snow upon the summit was indurated, but of an exceedingly fine grain, and the beautiful effect already referred to as noticed upon the stelvio was strikingly manifest. the hole made by driving the bâton into the snow was filled with a delicate blue light; and, by management, its complementary pinky yellow could also be produced. even the iron spike at the end of the bâton made a hole sufficiently deep to exhibit the blue colour, which certainly depends on the size and arrangement of the snow crystals. the firmament above us was without a cloud, and of a darkness almost equal to that which surrounded the moon at a.m. still, though the sun was shining, a breeze, whose tooth had been sharpened by its passage over the snow-fields, searched us through and through. the day was also waning, and, urged by the warnings of our ever prudent guide, we at length began the descent. [sidenote: an unexpected glissade. .] gravity was now in our favour, but gravity could not entirely spare our wearied limbs, and where we sank in the snow we found our downward progress very trying. i suffered from thirst, but after we had divided the liquefied snow at the petits mulets amongst us we had nothing to drink. i crammed the clean snow into my mouth, but the process of melting was slow and tantalizing to a parched throat, while the chill was painful to the teeth. we marched along the corridor, and crossed cautiously the perilous slope on which we had cut steps in the morning, breathing more freely after we had cleared the ice-precipice before described. along the base of this precipice we now wound, diverging from our morning's track, in order to get surer footing in the snow; it was like flour, and while descending to the grand plateau we sometimes sank in it nearly to the waist. when i endeavoured to squeeze it, so as to fill my flask, it at first refused to cling together, behaving like so much salt; the heat of the hand, however, soon rendered it a little moist, and capable of being pressed into compact masses. the sun met us here with extraordinary power; the heat relaxed my muscles, but when fairly immersed in the shadow of the dôme du goûter, the coolness restored my strength, which augmented as the evening advanced. simond insisted on the necessity of haste, to save us from the perils of darkness. "_on peut périr_" was his repeated admonition, and he was quite right. we reached the region of _ponts_, more weary, but, in compensation, more callous, than we had been in the morning, and moved over the soft snow of the bridges as if we had been walking upon eggs. the valley of chamouni was filled with brown-red clouds, which crept towards us up the mountain; the air around and above us was, however, clear, and the chastened light told us that day was departing. once as we hung upon a steep slope, where the snow was exceedingly soft, hirst omitted to make his footing sure; the soft mass gave way, and he fell, uttering a startled shout as he went down the declivity. i was attached to him, and, fixing my feet suddenly in the snow, endeavoured to check his fall, but i seemed a mere feather in opposition to the force with which he descended.[c] i fell, and went down after him; and we carried quite an avalanche of snow along with us, in which we were almost completely hidden at the bottom of the slope. all further dangers, however, were soon past, and we went at a headlong speed to the base of the grands mulets; the sound of our bâtons against the rocks calling huxley forth. a position more desolate than his had been can hardly be imagined. for seventeen hours he had been there. he had expected us at two o'clock in the afternoon; the hours came and passed, and till seven in the evening he had looked for us. "to the end of my life," he said, "i shall never forget the sound of those bâtons." it was his turn now to nurse me, which he did, repaying my previous care of him with high interest. we were all soon stretched, and, in spite of cold and hard boards, i slept at intervals; but the night, on the whole, was a weary one, and we rose next morning with muscles more tired than when we lay down. [sidenote: blind amid the crevasses. .] _friday, th august._--hirst was almost blind this morning; and our guide's eyes were also greatly inflamed. we gathered our things together, and bade the grands mulets farewell. it had frozen hard during the night, and this, on the steeper slopes, rendered the footing very insecure. simond, moreover, appeared to be a little bewildered, and i sometimes preceded him in cutting the steps, while hirst moved among the crevasses like a blind man; one of us keeping near him, so that he might feel for the actual places where our feet had rested, and place his own in the same position. it cost us three hours to cross from the grands mulets to the pierre a l'echelle, where we discarded our leggings, had a mouthful of food, and a brief rest. once upon the safe earth simond's powers seemed to be restored, and he led us swiftly downwards to the little auberge beside the cascade du tard, where we had some excellent lemonade, equally choice cognac, fresh strawberries and cream. how sweet they were, and how beautiful we thought the peasant girl who served them! our guide kept a little hotel, at which we halted, and found it clean and comfortable. we were, in fact, totally unfit to go elsewhere. my coat was torn, holes were kicked through my boots, and i was altogether ragged and shabby. a warm bath before dinner refreshed all mightily. dense clouds now lowered upon mont blanc, and we had not been an hour at chamouni when the breaking up of the weather was announced by a thunder-peal. we had accomplished our journey just in time. footnotes: [a] those acquainted with the mountain will at once recognise the grave error here committed. in fact on starting from the grands mulets we had crossed the glacier too far, and throughout were much too close to the dôme du goûter. [b] i fired the second case in a field in hampshire, and, as far as my memory enabled me to make the comparison, found its sound considerably _denser_, if i may use the expression. in i had a pistol fired at the summit of mont blanc: its sound was sensibly feebler and _shorter_ than in the valley; it resembled somewhat the discharge of a cork from a champagne bottle, though much louder, but it could not be at all compared to the sound of a common cracker. [c] i believe that i could stop him now ( ). ( .) [sidenote: happy evenings. .] after our return we spent every available hour upon the ice, working at questions which shall be treated under their proper heads, each day's work being wound up by an evening of perfect enjoyment. roast mutton and fried potatoes were our incessant fare, for which, after a little longing for a change at first, we contracted a final and permanent love. as the year advanced, moreover, and the grass sprouted with augmented vigour on the slopes of the montanvert, the mutton, as predicted by our host, became more tender and juicy. we had also some capital sallenches beer, cold as the glacier water, but effervescent as champagne. such were our food and drink. after dinner we gathered round the pine-fire, and i can hardly think it possible for three men to be more happy than we then were. it was not the goodness of the conversation, nor any high intellectual element, which gave the charm to our gatherings; the gladness grew naturally out of our own perfect health, and out of the circumstances of our position. every fibre seemed a repository of latent joy, which the slightest stimulus sufficed to bring into conscious action. [sidenote: a glacier "blower." .] on the th i penetrated with simond through thick gloom to the tacul; on the th we set stakes at the same place: on the same day, while crossing the medial moraine of the talèfre, a little below the cascade, a singular noise attracted my attention; it seemed at first as if a snake were hissing about my feet. on changing my position the sound suddenly ceased, but it soon recommenced. there was some snow upon the glacier, which i removed, and placed my ear close to the ice, but it was difficult to fix on the precise spot from which the sound issued. i cut away the disintegrated portion of the surface, and at length discovered a minute crack, from which a stream of air issued, which i could feel as a cold blast against my hand. while cutting away the surface further, i stopped the little "blower." a marmot screamed near me, and while i paused to look at the creature scampering up the crags, the sound commenced again, changing its note variously--hissing like a snake, singing like a kettle, and sometimes chirruping intermittently like a bird. on passing my fingers to and fro over the crack, i obtained a succession of audible puffs; the current was sufficiently strong to blow away the corner of a gauze veil held over the fissure. still the crack was not wide enough to permit of the entrance of my finger nail; and to issue with such force from so minute a rent the air must have been under considerable pressure. the origin of the blower was in all probability the following:--when the ice is recompacted after having descended a cascade, it is next to certain that chambers of air will be here and there enclosed, which, being powerfully squeezed afterwards, will issue in the manner described whenever a crack in the ice furnishes it with a means of escape. in my experiments on flowing mud, for example, the air entrapped in the mass while descending from the sluice into the trough, bursts in bubbles from the surface at a short distance downwards. [sidenote: a difficult line. .] i afterwards examined the talèfre cascade from summit to base, with reference to the structure, until at the close of the day thickening clouds warned me off. i went down the glacier at a trot, guided by the boulders capped with little cairns which marked the route. the track which i had pursued for the last five weeks amid the crevasses near l'angle was this day barely passable. the glacier had changed, my work was drawing to a close, and, as i looked at the objects which had now become so familiar to me, i felt that, though not viscous, the ice did not lack the quality of "adhesiveness," and i felt a little sad at the thought of bidding it so soon farewell. at some distance below the montanvert the mer de glace is riven from side to side by transverse crevasses: these fissures indicate that the glacier where they occur is in a state of longitudinal strain which produces transverse fracture. i wished to ascertain the amount of stretching which the glacier here demanded, and which the ice was not able to give; and for this purpose desired to compare the velocity of a line set out across the fissured portion with that of a second line staked out across the ice before it had become thus fissured. a previous inspection of the glacier through the telescope of our theodolite induced us to fix on a place which, though much riven, still did not exclude the hope of our being able to reach the other side. each of us was, as usual, armed with his own axe; and carrying with us suitable stakes, my guide and myself entered upon this portion of the glacier on the morning of the th of august. [sidenote: "nous nous trouverons perdus!" .] i was surprised on entering to find some veins of white ice, which from their position and aspect appeared to be derived from the glacier du géant; but to these i shall subsequently refer. our work was extremely difficult; we penetrated to some distance along one line, but were finally forced back, and compelled to try another. right and left of us were profound fissures, and once a cone of ice forty feet high leaned quite over our track. in front of us was a second leaning mass borne by a mere stalk, and so topheavy that one wondered why the slight pedestal on which it rested did not suddenly crack across. we worked slowly forwards, and soon found ourselves in the shadow of the topheavy mass above referred to; and from which i escaped with a wounded hand, caused by over-haste. simond surmounted the next ridge and exclaimed, "_nous nous trouverons perdus!_" i reached his side, and on looking round the place saw that there was no footing for man. the glacier here, as shown in the frontispiece, was cut up into thin wedges, separated from each other by profound chasms, and the wedges were so broken across as to render creeping along their edges quite impossible. thus brought to a stand, i fixed a stake at the point where we were forced to halt, and retreated along edges of detestable granular ice, which fell in showers into the crevasses when struck by the axe. at one place an exceedingly deep fissure was at our left, which was joined, at a sharp angle, by another at our right, and we were compelled to cross at the place of intersection: to do this we had to trust ourselves to a projecting knob of that vile rotten ice which i had learned to fear since my experience of it on the col du géant. we finally escaped, and set out our line at another place, where the glacier, though badly cut, was not impassable. [sidenote: farewell to the montanvert. .] on the th we made a series of final measurements at the tacul, and determined the motion of two lines which we had set out the previous day. on the st we quitted the montanvert; i had been there from the th of july, and the longer i remained the better i liked the establishment and the people connected with it. it was then managed by joseph tairraz and jules charlet, both of whom showed us every attention. in and i had occasion to revisit the establishment, which was then managed by jules and his brother, and found in it the same good qualities. during my winter expedition of i also found the same readiness to assist me in every possible way; honest jules expressing his willingness to ascend through the snow to the auberge if i thought his presence would in any degree contribute to my comfort. we crossed the glacier, and descended by the chapeau to the cascade des bois, the inclination of which and of the lower portion of the glacier we then determined. the day was magnificent. looking upwards, the aiguilles de charmoz and du dru rose right and left like sentinels of the valley, while in front of us the ice descended the steep, a bewildering mass of crags and chasms. at the other side was the pine-clad slope of the montanvert. further on the aiguille du midi threw its granite pyramid between us and mont blanc; on the dôme du goûter the _séracs_ of the mountain were to be seen, while issuing as if from a cleft in the mountain side the glacier des bossons thrust through the black pines its snowy tongue. below us was the beautiful valley of chamouni itself, through which the arve and arveiron rushed like enlivening spirits. we finally examined a grand old moraine produced by a mer de glace of other ages, when the ice quite crossed the valley of chamouni and abutted against the opposite mountain-wall. [sidenote: edouard simond. .] simond had proved himself a very valuable assistant; he was intelligent and perfectly trustworthy; and though the peculiar nature of my work sometimes caused me to attempt things against which his prudence protested, he lacked neither strength nor courage. on reaching chamouni and adding up our accounts, i found that i had not sufficient cash to pay him; money was waiting for me at the post-office in geneva, and thither it was arranged that my friend hirst should proceed next morning, while i was to await the arrival of the money at chamouni. my guide heard of this arrangement, and divined its cause: he came to me, and in the most affectionate manner begged of me to accept from him the loan of francs. though i did not need the loan, the mode in which it was offered to me augmented the kindly feelings which i had long entertained towards simond, and i may add that my intercourse with him since has served only to confirm my first estimate of his worthiness. expedition of . ( .) [sidenote: doubts regarding structure. .] i had confined myself during the summer of to the mer de glace and its tributaries, desirous to make my knowledge accurate rather than extensive. i had made the acquaintance of all accessible parts of the glacier, and spared no pains to master both the details and the meaning of the laminated structure of the ice, but i found no fact upon which i could take my stand and say to an advocate of an opposing theory, "this is unassailable." in experimental science we have usually the power of changing the conditions at pleasure; if nature does not reply to a question we throw it into another form; a combining of conditions is, in fact, the essence of experiment. to meet the requirements of the present question, i could not twist the same glacier into various shapes, and throw it into different states of strain and pressure; but i might, by visiting many glaciers, find all needful conditions fulfilled in detail, and by observing these i hoped to confer upon the subject the character and precision of a true experimental inquiry. the summer of was accordingly devoted to this purpose, when i had the good fortune to be accompanied by professor ramsay, the author of some extremely interesting papers upon ancient glaciers. taking zürich, schaffhausen, and lucerne in our way, we crossed the brünig on the nd of july, and met my guide, christian lauener, at meyringen. on the rd we visited the glacier of rosenlaui, and the glacier of the schwartzwald, and reached grindelwald in the evening of the same day. my expedition with mr. huxley had taught me that the lower grindelwald glacier was extremely instructive, and i was anxious to see many parts of it once more; this i did, in company with ramsay, and we also spent a day upon the upper glacier, after which our path lay over the strahleck to the glaciers of the aar and of the rhone. passage of the strahleck. ( .) [sidenote: a gloomy prospect. .] on monday, the th of july, we were called at a.m., and found the weather very unpromising, but the two mornings which preceded it had also been threatening without any evil result. there was, it is true, something more than usually hostile in the aspect of the clouds which sailed sullenly from the west, and smeared the air and mountains as if with the dirty smoke of a manufacturing town. we despatched our coffee, went down to the bottom of the grindelwald valley, up the opposite slope, and were soon amid the gloom of the pines which partially cover it. on emerging from these, a watery gleam on the mottled head of the eiger was the only evidence of direct sunlight in that direction. to our left was the wetterhorn surrounded by wild and disorderly clouds, through the fissures of which the morning light glared strangely. for a time the heisse platte was seen, a dark brown patch amid the ghastly blue which overspread the surrounding slopes of snow. the clouds once rolled up, and revealed for a moment the summits of the viescherhörner; but they immediately settled down again, and hid the mountains from top to base. soon afterwards they drew themselves partially aside, and a patch of blue over the strahleck gave us hope and pleasure. as we ascended, the prospect in front of us grew better, but that behind us--and the wind came from behind--grew worse. slowly and stealthily the dense neutral-tint masses crept along the sides of the mountains, and seemed to dog us like spies; while over the glacier hung a thin veil of fog, through which gleamed the white minarets of the ice. [sidenote: ice cascade and protuberances. .] [sidenote: dirt-bands of the strahleck branch. .] when we first spoke of crossing the strahleck, lauener said it would be necessary to take two guides at least; but after a day's performance on the ice he thought we might manage very well by taking, in addition to himself, the herd of the alp, over the more difficult part of the pass. he had further experience of us on the second day, and now, as we approached the herd's hut, i was amused to hear him say that he thought any assistance beside his own unnecessary. relying upon ourselves, therefore, we continued our route, and were soon upon the glacier, which had been rendered smooth and slippery through the removal of its disintegrated surface by the warm air. crossing the strahleck branch of the glacier to its left side, we climbed the rocks to the grass and flowers which clothe the slopes above them. our way sometimes lay over these, sometimes along the beds of streams, across turbulent brooks, and once around the face of a cliff, which afforded us about an inch of ledge to stand upon, and some protruding splinters to lay hold of by the hands. having reached a promontory which commanded a fine view of the glacier, and of the ice cascade by which it was fed, i halted, to check the observations already made from the side of the opposite mountain. here, as there, cliffy ridges were seen crossing the cascade of the glacier, with interposed spaces of dirt and débris--the former being toned down, and the latter squeezed towards the base of the fall, until finally the ridges swept across the glacier, in gentle swellings, from side to side; while the valleys between them, holding the principal share of the superficial impurity, formed the cradles of the so-called dirt-bands. these swept concentric with the protuberances across the glacier, and remained upon its surface even after the swellings had disappeared. the swifter flow of the centre of the glacier tends of course incessantly to lengthen the loops of the bands, and to thrust the summits of the curves which they form more and more in advance of their lateral portions. the depressions between the protuberances appeared to be furrowed by minor wrinkles, as if the ice of the depressions had yielded more than that of the protuberances. this, i think, is extremely probable, though it has never yet been proved. three stakes, placed, one on the summit, another on the frontal slope, and another at the base of a protuberance, would, i think, move with unequal velocities. they would, i think, show that, upon the large and general motion of the glacier, smaller motions are superposed, as minor oscillations are known to cover parasitically the large ones of a vibrating string. possibly, also, the dirt-bands may owe something to the squeezing of impurities out of the glacier to its surface in the intervals between the swellings. from our present position we could also see the swellings on the viescherhörner branch of the glacier, in the valleys between which coarse shingle and débris were collected, which would form dirt-bands if they could. on neither branch, however, do the bands attain the definition and beauty which they possess upon the mer de glace. after an instructive lesson we faced our task once more, passing amid crags and boulders, and over steep moraines, from which the stones rolled down upon the slightest disturbance. while crossing a slope of snow with an inclination of °, my footing gave way, i fell, but turned promptly on my face, dug my staff deeply into the snow, and arrested the motion before i had slid a dozen yards. ramsay was behind me, speculating whether he should be able to pass the same point without slipping; before he reached it, however, the snow yielded, he fell, and slid swiftly downwards. lauener, whose attention had been aroused by my fall, chanced to be looking round when ramsay's footing yielded. with the velocity of a projectile he threw himself upon my companion, seized him, and brought him to rest before he had reached the bottom of the slope. the act made a very favourable impression upon me, it was so prompt and instinctive. an eagle could not swoop upon its prey with more directness of aim and swiftness of execution. [sidenote: ice cliffs through the fog. .] while this went on the clouds were playing hide and seek with the mountains. the ice-crags and pinnacles to our left, looming through the haze, seemed of gigantic proportions, reminding one of the hades of byron's 'cain.' "how sunless and how vast are these dim realms!" we climbed for some time along the moraine which flanks the cascade, and on reaching the level of the brow lauener paused, cast off his knapsack, and declared for breakfast. while engaged with it the dense clouds which had crammed the gorge and obscured the mountains, all melted away, and a scene of indescribable magnificence was revealed. overhead the sky suddenly deepened to dark blue, and against it the finsteraarhorn projected his dark and mighty mass. brown spurs jutted from the mountain, and between them were precipitous snow-slopes, fluted by the descent of rocks and avalanches, and broken into ice-precipices lower down. right in front of us, and from its proximity more gigantic to the eye, was the schreckhorn, while from couloirs and mountain-slopes the matter of glaciers yet to be was poured into the vast basin on the rim of which we now stood. [sidenote: mutations of the clouds. .] this it was next our object to cross; our way lying in part through deep snow-slush, the scene changing perpetually from blue heaven to gray haze which massed itself at intervals in dense clouds about the mountains. after crossing the basin our way lay partly over slopes of snow, partly over loose shingle, and at one place along the edge of a formidable precipice of rock. we sat down sometimes to rest, and during these pauses, though they were very brief, the scene had time to go through several of its protean mutations. at one moment all would be perfectly serene, no cloud in the transparent air to tell us that any portion of it was in motion, while the blue heaven threw its flattened arch over the magnificent amphitheatre. then in an instant, from some local cauldron, the vapour would boil up suddenly, eddying wildly in the air, which a moment before seemed so still, and enveloping the entire scene. thus the space enclosed by the finsteraarhorn, the viescherhörner, and the schreckhorn, would at one moment be filled with fog to the mountain heads, every trace of which a few minutes sufficed to sweep away, leaving the unstained blue of heaven behind it, and the mountains showing sharp and jagged outlines in the glassy air. one might be almost led to imagine that the vapour molecules endured a strain similar to that of water cooled below its freezing point, or heated beyond its boiling point; and that, on the strain being relieved by the sudden yielding of the opposing force, the particles rushed together, and thus filled in an instant the clear atmosphere with aqueous precipitation. i had no idea that the strahleck was so fine a pass. whether it is the quality of my mind to take in the glory of the present so intensely as to make me forgetful of the glory of the past, i know not, but it appeared to me that i had never seen anything finer than the scene from the summit. the amphitheatre formed by the mountains seemed to me of exceeding magnificence; nor do i think that my feeling was subjective merely; for the simple magnitude of the masses which built up the spectacle would be sufficient to declare its grandeur. looking down towards the glacier of the aar, a scene of wild beauty and desolation presented itself. not a trace of vegetation could be seen along the whole range of the bounding mountains; glaciers streamed from their shoulders into the valley beneath, where they welded themselves to form the finsteraar affluent of the unteraar glacier. [sidenote: descent of the crags. .] after a brief pause, lauener again strapped on his knapsack, and tempered both will and muscles by the remark, that our worst piece of work was now before us. from the place where we sat, the mountain fell precipitously for several hundred feet; and down the weathered crags, and over the loose shingle which encumbered their ledges, our route now lay. lauener was in front, cool and collected, lending at times a hand to ramsay, and a word of encouragement to both of us, while i brought up the rear. i found my full haversack so inconvenient that i once or twice thought of sending it down the crags in advance of me, but lauener assured me that it would be utterly destroyed before reaching the bottom. my complaint against it was, that at critical places it sometimes came between me and the face of the cliff, pushing me away from the latter so as to throw my centre of gravity almost beyond the base intended to support it. we came at length upon a snow-slope, which had for a time an inclination of °; then once more to the rocks; again to the snow, which was both steep and deep. our bâtons were at least six feet long: we drove them into the snow to secure an anchorage, but they sank to their very ends, and we merely retained a length of them sufficient for a grasp. this slope was intersected by a so-called bergschrund, the lower portion of the slope being torn away from its upper portion so as to form a crevasse that extended quite round the head of the valley. we reached its upper edge; the chasm was partially filled with snow, which brought its edges so near that we cleared it by a jump. the rest of the slope was descended by a _glissade_. each sat down upon the snow, and the motion, once commenced, swiftly augmented to the rate of an avalanche, and brought us pleasantly to the bottom. [sidenote: through gloom to the grimsel. .] as we looked from the heights, we could see that the valley through which our route lay was filled with gray fog: into this we soon plunged, and through it we made our way towards the abschwung. the inclination of the glacier was our only guide, for we could see nothing. reaching the confluence of the finsteraar and lauteraar branches, we went downwards with long swinging strides, close alongside the medial moraine of the trunk glacier. the glory of the morning had its check in the dull gloom of the evening. across streams, amid dirt-cones and glacier-tables, and over the long reach of shingle which covers the end of the glacier, we plodded doggedly, and reached the grimsel at p.m., the journey having cost a little more than hours. ( .) [sidenote: ancient glacier action. .] we made the grimsel our station for a day, which was spent in examining the evidences of ancient glacier action in the valley of hasli. near the hospice, but at the opposite side of the aar, rises a mountain-wall of hard granite, on which the flutings and groovings are magnificently preserved. after a little practice the eye can trace with the utmost precision the line which marks the level of the ancient ice: above this the crags are sharp and rugged; while below it the mighty grinder has rubbed off the pinnacles of the rocks and worn their edges away. the height to which this action extends must be nearly two thousand feet above the bed of the present valley. it is also easy to see the depth to which the river has worked its channel into the ancient rocks. in some cases the road from guttanen to the grimsel lay right over the polished rocks, asperities being supplied by the chisel of man in order to prevent travellers from slipping on their slopes. here and there also huge protuberant crags were rounded into domes almost as perfect as if chiselled by art. to both my companion and myself this walk was full of instruction and delight. on the th of july we crossed the grimsel pass, and traced the scratchings to the very top of it. ramsay remarked that their direction changed high up the pass, as if a tributary from the summit had produced them, while lower down they merged into the general direction of the glacier which had filled the principal valley. from the summit of the mayenwand we had a clear view of the glacier of the rhone; and to see the lower portion of this glacier to advantage no better position can be chosen. the dislocation of its cascade, the spreading out of the ice below, its system of radial crevasses, and the transverse sweep of its structural groovings, may all be seen. a few hours afterwards we were among the wild chasms at the brow of the ice-fall, where we worked our way to the centre of the ice, but were unable to attain the opposite side. having examined the glacier both above and below the cascade, we went down the valley to viesch, and ascended thence, on the th of july, to the hôtel jungfrau on the slopes of the Æggischhorn. on the following day we climbed to the summit of the mountain, and from a sheltered nook enjoyed the glorious prospect which it commands. the wind was strong, and fleecy clouds flew over the heavens; some of which, as they formed and dispersed themselves about the flanks of the aletschhorn, showed extraordinary iridescences. [sidenote: the mÄrjelen see. .] the sunbeams called us early on the morning of the st of august. no cloud rested on the opposite range of the valais mountains, but on looking towards the Æggischhorn we found a cap upon its crest; we looked again--the cap had disappeared and a serene heaven stretched overhead. as we breasted the alp the moon was still in the sky, paling more and more before the advancing day; a single hawk swung in the atmosphere above us; clear streams babbled from the hills, the louder sounds reposing on a base of music; while groups of cows with tinkling bells browsed upon the green alp. here and there the grass was dispossessed, and the flanks of the mountain were covered by the blocks which had been cast down from the summit. on reaching the plateau at the base of the final pyramid, we rounded the mountain to the right and came over the lonely and beautiful märjelen see. no doubt the hollow which this lake fills had been scooped out in former ages by a branch of the aletsch glacier; but long ago the blue ice gave place to blue water. the glacier bounds it at one side by a vertical wall of ice sixty feet in height: this is incessantly undermined, a roof of crystal being formed over the water, till at length the projecting mass, becoming too heavy for its own rigidity, breaks and tumbles into the lake. here, attacked by sun and air, its blue surface is rendered dazzlingly white, and several icebergs of this kind now floated in the sunlight; the water was of a glassy smoothness, and in its blue depths each ice mass doubled itself by reflection.[a] [sidenote: the aletsch glacier. .] the aletsch is the grandest glacier in the alps: over it we now stood, while the bounding mountains poured vast feeders into the noble stream. the jungfrau was in front of us without a cloud, and apparently so near that i proposed to my guide to try it without further preparation. he was enthusiastic at first, but caution afterwards got the better of his courage. at some distance up the glacier the snow-line was distinctly drawn, and from its edge upwards the mighty shoulders of the hills were heavy laden with the still powdery material of the glacier. amid blocks and débris we descended to the ice: the portion of it which bounded the lake had been sapped, and a space of a foot existed between ice and water: numerous chasms were formed here, the mass being thus broken, preparatory to being sent adrift upon the lake. we crossed the glacier to its centre, and looking down it the grand peaks of the mischabel, the noble cone of the weisshorn, and the dark and stern obelisk of the matterhorn, formed a splendid picture. looking upwards, a series of most singularly contorted dirt-bands revealed themselves upon the surface of the ice. i sought to trace them to their origin, but was frustrated by the snow which overspread the upper portion of the glacier. along this we marched for three hours, and came at length to the junction of the four tributary valleys which pour their frozen streams into the great trunk valley. the glory of the day, and that joy of heart which perfect health confers, may have contributed to produce the impression, but i thought i had never seen anything to rival in magnificence the region in the heart of which we now found ourselves. we climbed the mountain on the right-hand side of the glacier, where, seated amid the riven and weather-worn crags, we fed our souls for hours on the transcendent beauty of the scene. [sidenote: a chamois deceived. .] we afterwards redescended to the glacier, which at this place was intersected by large transverse crevasses, many of which were apparently filled with snow, while over others a thin and treacherous roof was thrown. in some cases the roof had broken away, and revealed rows of icicles of great length and transparency pendent from the edges. we at length turned our faces homewards, and looking down the glacier i saw at a great distance something moving on the ice. i first thought it was a man, though it seemed strange that a man should be there alone. on drawing my guide's attention to it he at once pronounced it to be a chamois, and i with my telescope immediately verified his statement. the creature bounded up the glacier at intervals, and sometimes the vigour of its spring showed that it had projected itself over a crevasse. it approached us sometimes at full gallop: then would stop, look toward us, pipe loudly, and commence its race once more. it evidently made the reciprocal mistake to my own, imagining us to be of its own kith and kin. we sat down upon the ice the better to conceal our forms, and to its whistle our guide whistled in reply. a joyous rush was the creature's first response to the signal; but it afterwards began to doubt, and its pauses became more frequent. its form at times was extremely graceful, the head erect in the air, its apparent uprightness being augmented by the curvature which threw its horns back. i watched the animal through my glass until i could see the glistening of its eyes; but soon afterwards it made a final pause, assured itself of its error, and flew with the speed of the wind to its refuge in the mountains. footnotes: [a] a painting of this exquisite lake has been recently executed by mr. george barnard. ascent of the finsteraarhorn, . ( .) [sidenote: my guide. .] since my arrival at the hotel on the th of july i had once or twice spoken about ascending the finsteraarhorn, and on the nd of august my host advised me to avail myself of the promising weather. a guide, named bennen, was attached to the hotel, a remarkable-looking man, between and years old, of middle stature, but very strongly built. his countenance was frank and firm, while a light of good-nature at times twinkled in his eye. altogether the man gave me the impression of physical strength, combined with decision of character. the proprietor had spoken to me many times of the strength and courage of this man, winding up his praises of him by the assurance that if i were killed in bennen's company there would be two lives lost, for that the guide would assuredly sacrifice himself in the effort to save his _herr_. he was called, and i asked him whether he would accompany me alone to the top of the finsteraarhorn. to this he at first objected, urging the possibility of his having to render me assistance, and the great amount of labour which this might entail upon him; but this was overruled by my engaging to follow where he led, without asking him to render me any help whatever. he then agreed to make the trial, stipulating, however, that he should not have much to carry to the cave of the faulberg, where we were to spend the night. to this i cordially agreed, and sent on blankets, provisions, wood, and hay, by two porters. [sidenote: iridescent cloud. .] my desire, in part, was to make a series of observations at the summit of the mountain, while a similar series was made by professor ramsay in the valley of the rhone, near viesch, with a view to ascertaining the permeability of the lower strata of the atmosphere to the radiant heat of the sun. during the forenoon of the nd i occupied myself with my instruments, and made the proper arrangements with ramsay. i tested a mountain-thermometer which mr. casella had kindly lent me, and found the boiling point of water on the dining-room table of the hotel to be . ° fahrenheit. at about three o'clock in the afternoon we quitted the hotel, and proceeded leisurely with our two guides up the slope of the Æggischhorn. we once caught a sight of the topmost pinnacle of the finsteraarhorn; beside it was the rothhorn, and near this again the oberaarhorn, with the viescher glacier streaming from its shoulders. on the opposite side we could see, over an oblique buttress of the mountain on which we stood, the snowy summit of the weisshorn; to the left of this was the ever grim and lonely matterhorn; and farther to the left, with its numerous snow-cones, each with its attendant shadow, rose the mighty mischabel. we descended, and crossed the stream which flows from the märjelen see, into which a large mass of the glacier had recently fallen, and was now afloat as an iceberg. we passed along the margin of the lake, and at the junction of water and ice i bade ramsay good-bye. at the commencement of our journey upon the ice, whenever we crossed a crevasse, i noticed bennen watching me; his vigilance, however, soon diminished, whence i gathered that he finally concluded that i was able to take care of myself. clouds hovered in the atmosphere throughout the whole time of our ascent; one smoky-looking mass marred the glory of the sunset, but at some distance was another which exhibited colours almost as rich and varied as those of the solar spectrum. i took the glorious banner thus unfurled as a sign of hope, to check the despondency which its gloomy neighbour was calculated to produce. [sidenote: evening near the jungfrau. .] two hours' walking brought us near our place of rest; the porters had already reached it, and were now returning. we deviated to the right, and, having crossed some ice-ravines, reached the lateral moraine of the glacier, and picked our way between it and the adjacent mountain-wall. we then reached a kind of amphitheatre, crossed it, and climbing the opposite slope, came to a triple grotto formed by clefts in the mountain. in one of these a pine-fire was soon blazing briskly, and casting its red light upon the surrounding objects, though but half dispelling the gloom from the deeper portions of the cell. i left the grotto, and climbed the rocks above it to look at the heavens. the sun had quitted our firmament, but still tinted the clouds with red and purple; while one peak of snow in particular glowed like fire, so vivid was its illumination. during our journey upwards the jungfrau never once showed her head, but, as if in ill temper, had wrapped her vapoury veil around her. she now looked more good-humoured, but still she did not quite remove her hood; though all the other summits, without a trace of cloud to mask their beautiful forms, pointed heavenward. the calmness was perfect; no sound of living creature, no whisper of a breeze, no gurgle of water, no rustle of débris, to break the deep and solemn silence. surely, if beauty be an object of worship, those glorious mountains, with rounded shoulders of the purest white--snow-crested and star-gemmed--were well calculated to excite sentiments of adoration. [sidenote: the cave of the faulberg. .] i returned to the grotto, where supper was prepared and waiting for me. the boiling point of water, at the level of the "kitchen" floor, i found to be ° fahr. nothing could be more picturesque than the aspect of the cave before we went to rest. the fire was gleaming ruddily. i sat upon a stone bench beside it, while bennen was in front with the red light glimmering fitfully over him. my boiling-water apparatus, which had just been used, was in the foreground; and telescopes, opera-glasses, haversacks, wine-keg, bottles, and mattocks, lay confusedly around. the heavens continued to grow clearer, the thin clouds, which had partially overspread the sky, melting gradually away. the grotto was comfortable; the hay sufficient materially to modify the hardness of the rock, and my position at least sheltered and warm. one possibility remained that might prevent me from sleeping--the snoring of my companion; he assured me, however, that he did not snore, and we lay down side by side. the good fellow took care that i should not be chilled; he gave me the best place, by far the best part of the clothes, and may have suffered himself in consequence; but, happily for him, he was soon oblivious of this. physiologists, i believe, have discovered that it is chiefly during sleep that the muscles are repaired; and ere long the sound i dreaded announced to me at once the repair of bennen's muscles and the doom of my own. the hollow cave resounded to the deep-drawn snore. i once or twice stirred the sleeper, breaking thereby the continuity of the phenomenon; but it instantly pieced itself together again, and went on as before. i had not the heart to wake him, for i knew that upon him would devolve the chief labour of the coming day. at half-past one he rose and prepared coffee, and at two o'clock i was engaged upon the beverage. we afterwards packed up our provisions and instruments. bennen bore the former, i the latter, and at three o'clock we set out. [sidenote: "shall we try the jungfrau?" .] we first descended a steep slope to the glacier, along which we walked for a time. a spur of the faulberg jutted out between us and the ice-laden valley through which we must pass; this we crossed in order to shorten our way and to avoid crevasses. loose shingle and boulders overlaid the mountain; and here and there walls of rock opposed our progress, and rendered the route far from agreeable. we then descended to the grünhorn tributary, which joins the trunk glacier at nearly a right angle, being terminated by a saddle which stretches across from mountain to mountain, with a curvature as graceful and as perfect as if drawn by the instrument of a mathematician. the unclouded moon was shining, and the jungfrau was before us so pure and beautiful, that the thought of visiting the "maiden" without further preparation occurred to me. i turned to bennen, and said, "shall we try the jungfrau?" i think he liked the idea well enough, though he cautiously avoided incurring any responsibility. "if you desire it, i am ready," was his reply. he had never made the ascent, and nobody knew anything of the state of the snow this year; but lauener had examined it through a telescope on the previous day, and pronounced it dangerous. in every ascent of the mountain hitherto made, ladders had been found indispensable, but we had none. i questioned bennen as to what he thought of the probabilities, and tried to extract some direct encouragement from him; but he said that the decision rested altogether with myself, and it was his business to endeavour to carry out that decision. "we will attempt it, then," i said, and for some time we actually walked towards the jungfrau. a gray cloud drew itself across her summit, and clung there. i asked myself why i deviated from my original intention? the finsteraarhorn was higher, and therefore better suited for the contemplated observations. i could in no wise justify the change, and finally expressed my scruples. a moment's further conversation caused us to "right about," and front the saddle of the grünhorn. [sidenote: magnificent scene. .] the dawn advanced. the eastern sky became illuminated and warm, and high in the air across the ridge in front of us stretched a tongue of cloud like a red flame, and equally fervid in its hue. looking across the trunk glacier, a valley which is terminated by the lötsch saddle was seen in a straight line with our route, and i often turned to look along this magnificent corridor. the mightiest mountains in the oberland form its sides; still, the impression which it makes is not that of vastness or sublimity, but of loveliness not to be described. the sun had not yet smitten the snows of the bounding mountains, but the saddle carved out a segment of the heavens which formed a background of unspeakable beauty. over the rim of the saddle the sky was deep orange, passing upwards through amber, yellow, and vague ethereal green to the ordinary firmamental blue. right above the snow-curve purple clouds hung perfectly motionless, giving depth to the spaces between them. there was something saintly in the scene. anything more exquisite i had never beheld. we marched upwards over the smooth crisp snow to the crest of the saddle, and here i turned to take a last look along that grand corridor, and at that wonderful "daffodil sky." the sun's rays had already smitten the snows of the aletschhorn; the radiance seemed to infuse a principle of life and activity into the mountains and glaciers, but still that holy light shone forth, and those motionless clouds floated beyond, reminding one of that eastern religion whose essence is the repression of all action and the substitution for it of immortal calm. the finsteraarhorn now fronted us; but clouds turbaned the head of the giant, and hid it from our view. the wind, however, being north, inspired us with a strong hope that they would melt as the day advanced. i have hardly seen a finer ice-field than that which now lay before us. considering the _névé_ which supplies it, it appeared to me that the viescher glacier ought to discharge as much ice as the aletsch; but this is an error due to the extent of _névé_ which is here at once visible: since a glance at the map of this portion of the oberland shows at once the great superiority of the mountain treasury from which the aletsch glacier draws support. still, the ice-field before us was a most noble one. the surrounding mountains were of imposing magnitude, and loaded to their summits with snow. down the sides of some of them the half-consolidated mass fell in a state of wild fracture and confusion. in some cases the riven masses were twisted and overturned, the ledges bent, and the detached blocks piled one upon another in heaps; while in other cases the smooth white mass descended from crown to base without a wrinkle. the valley now below us was gorged by the frozen material thus incessantly poured into it. we crossed it, and reached the base of the finsteraarhorn, ascended the mountain a little way, and at six o'clock paused to lighten our burdens and to refresh ourselves. [sidenote: the mountain assailed. .] the north wind had freshened, we were in the shade, and the cold was very keen. placing a bottle of tea and a small quantity of provisions in the knapsack, and a few figs and dried prunes in our pockets, we commenced the ascent. the finsteraarhorn sends down a number of cliffy buttresses, separated from each other by wide couloirs filled with ice and snow. we ascended one of these buttresses for a time, treading cautiously among the spiky rocks; afterwards we went along the snow at the edge of the spine, and then fairly parted company with the rock, abandoning ourselves to the _névé_ of the couloir. the latter was steep, and the snow was so firm that steps had to be cut in it. once i paused upon a little ledge, which gave me a slight footing, and took the inclination. the slope formed an angle of ° with the horizon; and across it, at a little distance below me, a gloomy fissure opened its jaws. the sun now cleared the summits which had before cut off his rays, and burst upon us with great power, compelling us to resort to our veils and dark spectacles. two years before, bennen had been nearly blinded by inflammation brought on by the glare from the snow, and he now took unusual care in protecting his eyes. the rocks looking more practicable, we again made towards them, and clambered among them till a vertical precipice, which proved impossible of ascent, fronted us. bennen scanned the obstacle closely as we slowly approached it, and finally descended to the snow, which wound at a steep angle round its base: on this the footing appeared to me to be singularly insecure, but i marched without hesitation or anxiety in the footsteps of my guide. [sidenote: the crest of rocks. .] we ascended the rocks once more, continued along them for some time, and then deviated to the couloir on our left. this snow-slope is much dislocated at its lower portion, and above its precipices and crevasses our route now lay. the snow was smooth, and sufficiently firm and steep to render the cutting of steps necessary. bennen took the lead: to make each step he swung his mattock once, and his hindmost foot rose exactly at the moment the mattock descended; there was thus a kind of rhythm in his motion, the raising of the foot keeping time to the swing of the implement. in this manner we proceeded till we reached the base of the rocky pyramid which caps the mountain. [sidenote: the summit gained. .] one side of the pyramid had been sliced off, thus dropping down almost a sheer precipice for some thousands of feet to the finsteraar glacier. a wall of rock, about or feet high, runs along the edge of the mountain, and this sheltered us from the north wind, which surged with the sound of waves against the tremendous barrier at the other side. "our hardest work is now before us," said my guide. our way lay up the steep and splintered rocks, among which we sought out the spikes which were closely enough wedged to bear our weight. each had to trust to himself, and i fulfilled to the letter my engagement with bennen to ask no help. my boiling-water apparatus and telescope were on my back, much to my annoyance, as the former was heavy, and sometimes swung awkwardly round as i twisted myself among the cliffs. bennen offered to take it, but he had his own share to carry, and i was resolved to bear mine. sometimes the rocks alternated with spaces of ice and snow, which we were at intervals compelled to cross; sometimes, when the slope was pure ice and very steep, we were compelled to retreat to the highest cliffs. the wall to which i have referred had given way in some places, and through the gaps thus formed the wind rushed with a loud, wild, wailing sound. through these spaces i could see the entire field of agassiz's observations; the junction of the lauteraar and finsteraar glaciers at the abschwung, the medial moraine between them, on which stood the hôtel des neufchâtelois, and the pavilion built by m. dollfuss, in which huxley and myself had found shelter two years before. bennen was evidently anxious to reach the summit, and recommended all observations to be postponed until after our success had been assured. i agreed to this, and kept close at his heels. strong as he was, he sometimes paused, laid his head upon his mattock, and panted like a chased deer. he complained of fearful thirst, and to quench it we had only my bottle of tea: this we shared loyally, my guide praising its virtues, as well he might. still the summit loomed above us; still the angry swell of the north wind, beating against the torn battlements of the mountain, made wild music. upward, however, we strained; and at last, on gaining the crest of a rock, bennen exclaimed, in a jubilant voice, "_die höchste spitze!_"--the highest point. in a moment i was at his side, and saw the summit within a few paces of us. a minute or two placed us upon the topmost-pinnacle, with the blue dome of heaven above us, and a world of mountains, clouds, and glaciers beneath. a notion is entertained by many of the guides that if you go to sleep at the summit of any of the highest mountains, you will "sleep the sleep that knows no waking." [sidenote: thermometer placed. .] bennen did not appear to entertain this superstition; and before starting in the morning, i had stipulated for ten minutes' sleep on reaching the summit, as part compensation for the loss of the night's rest. my first act, after casting a glance over the glorious scene beneath us, was to take advantage of this agreement; so i lay down and had five minutes' sleep, from which i rose refreshed and brisk. the sun at first beat down upon us with intense force, and i exposed my thermometers; but thin veils of vapour soon drew themselves before the sun, and denser mists spread over the valley of the rhone, thus destroying all possibility of concert between ramsay and myself. i turned therefore to my boiling-water apparatus, filled it with snow, melted the first charge, put more in, and boiled it; ascertaining the boiling point to be ° fahrenheit. on a sheltered ledge, about two or three yards south of the highest point, i placed a minimum-thermometer, in the hope that it would enable us in future years to record the lowest winter temperatures at the summit of the mountain.[a] [sidenote: scene from the summit. .] it is difficult to convey any just impression of the scene from the summit of the finsteraarhorn: one might, it is true, arrange the visible mountains in a list, stating their heights and distances, and leaving the imagination to furnish them with peaks and pinnacles, to build the precipices, polish the snow, rend the glaciers, and cap the highest summits with appropriate clouds. but if imagination did its best in this way, it would hardly exceed the reality, and would certainly omit many details which contribute to the grandeur of the scene itself. the various shapes of the mountains, some grand, some beautiful, bathed in yellow sunshine, or lying black and riven under the frown of impervious cumuli; the pure white peaks, cornices, bosses, and amphitheatres; the blue ice rifts, the stratified snow-precipices, the glaciers issuing from the hollows of the eternal hills, and stretching like frozen serpents through the sinuous valleys; the lower cloud field--itself an empire of vaporous hills--shining with dazzling whiteness, while here and there grim summits, brown by nature, and black by contrast, pierce through it like volcanic islands through a shining sea,--add to this the consciousness of one's position which clings to one _unconsciously_, that undercurrent of emotion which surrounds the question of one's personal safety, at a height of more than , feet above the sea, and which is increased by the weird strange sound of the wind surging with the full deep boom of the distant sea against the precipice behind, or rising to higher cadences as it forces itself through the crannies of the weatherworn rocks,--all conspire to render the scene from the finsteraarhorn worthy of the monarch of the bernese alps. [sidenote: "have no fear." .] [sidenote: discipline. .] my guide at length warned me that we must be moving; repeating the warning more impressively before i attended to it. we packed up, and as we stood beside each other ready to march he asked me whether we should tie ourselves together, at the same time expressing his belief that it was unnecessary. up to this time we had been separate, and the thought of attaching ourselves had not occurred to me till he mentioned it. i thought it, however, prudent to accept the suggestion, and so we united our destinies by a strong rope. "now," said bennen, "have no fear; no matter how you throw yourself, i will hold you." afterwards, on another perilous summit, i repeated this saying of bennen's to a strong and active guide, but his observation was that it was a hardy untruth, for that in many places bennen could not have held me. nevertheless a daring word strengthens the heart, and, though i felt no trace of that sentiment which bennen exhorted me to banish, and was determined, as far as in me lay, to give him no opportunity of trying his strength in saving me, i liked the fearless utterance of the man, and sprang cheerily after him. our descent was rapid, apparently reckless, amid loose spikes, boulders, and vertical prisms of rock, where a false step would assuredly have been attended with broken bones; but the consciousness of certainty in our movements never forsook us, and proved a source of keen enjoyment. the senses were all awake, the eye clear, the heart strong, the limbs steady, yet flexible, with power of recovery in store, and ready for instant action should the footing give way. such is the discipline which a perilous ascent imposes. [sidenote: descent by glissades. .] we finally quitted the crest of rocks, and got fairly upon the snow once more. we first went downwards at a long swinging trot. the sun having melted the crust which we were compelled to cut through in the morning, the leg at each plunge sank deeply into the snow; but this sinking was partly in the direction of the slope of the mountain, and hence assisted our progress. sometimes the crust was hard enough to enable us to glide upon it for long distances while standing erect; but the end of these _glissades_ was always a plunge and tumble in the deeper snow. once upon a steep hard slope bennen's footing gave way; he fell, and went down rapidly, pulling me after him. i fell also, but turning quickly, drove the spike of my hatchet into the ice, got good anchorage, and held both fast; my success assuring me that i had improved as a mountaineer since my ascent of mont blanc. we tumbled so often in the soft snow, and our clothes and boots were so full of it, that we thought we might as well try the sitting posture in gliding down. we did so, and descended with extraordinary velocity, being checked at intervals by a bodily immersion in the softer and deeper snow. i was usually in front of bennen, shooting down with the speed of an arrow and feeling the check of the rope when the rapidity of my motion exceeded my guide's estimate of what was safe. sometimes i was behind him, and darted at intervals with the swiftness of an avalanche right upon him; sometimes in the same transverse line with him, with the full length of the rope between us; and here i found its check unpleasant, as it tended to make me roll over. my feet were usually in the air, and it was only necessary to turn them right or left, like the helm of a boat, to change the direction of motion and avoid a difficulty, while a vigorous dig of leg and hatchet into the snow was sufficient to check the motion and bring us to rest. swiftly, yet cautiously, we glided into the region of crevasses, where we at last rose, quite wet, and resumed our walking, until we reached the point where we had left our wine in the morning, and where i squeezed the water from my wet clothes, and partially dried them in the sun. [sidenote: the viesch glacier. .] we had left some things at the cave of the faulberg, and it was bennen's first intention to return that way and take them home with him. finding, however, that we could traverse the viescher glacier almost to the Æggischhorn, i made this our highway homewards. at the place where we entered it, and for an hour or two afterwards, the glacier was cut by fissures, for the most part covered with snow. we had packed up our rope, and bennen admonished me to tread in his steps. three or four times he half disappeared in the concealed fissures, but by clutching the snow he rescued himself and went on as swiftly as before. once my leg sank, and the ring of icicles some fifty feet below told me that i was in the jaws of a crevasse; my guide turned sharply--it was the only time that i had seen concern on his countenance:-- "_gott's donner! sie haben meine tritte nicht gefolgt._" "_doch!_" was my only reply, and we went on. he scarcely tried the snow that he crossed, as from its form and colour he could in most cases judge of its condition. for a long time we kept at the left-hand side of the glacier, avoiding the fissures which were now permanently open. we came upon the tracks of a herd of chamois, which had clambered from the glacier up the sides of the oberaarhorn, and afterwards crossed the glacier to the right-hand side, my guide being perfect master of the ground. his eyes went in advance of his steps, and his judgment was formed before his legs moved. the glacier was deeply fissured, but there was no swerving, no retreating, no turning back to seek more practicable routes; each stride told, and every stroke of the axe was a profitable investment of labour. we left the glacier for a time, and proceeded along the mountain side, till we came near the end of the trift glacier, where we let ourselves down an awkward face of rock along the track of a little cascade, and came upon the glacier once more. here again i had occasion to admire the knowledge and promptness of my guide. the glacier, as is well known, is greatly dislocated, and has once or twice proved a prison to guides and travellers, but bennen led me through the confusion without a pause. we were sometimes in the middle of the glacier, sometimes on the moraine, and sometimes on the side of the flanking mountain. towards the end of the day we crossed what seemed to be the consolidated remains of a great avalanche; on this my foot slipped, there was a crevasse at hand, and a sudden effort was necessary to save me from falling into it. in making this effort the spike of my axe turned uppermost, and the palm of my hand came down upon it, thus receiving a very ugly wound. we were soon upon the green alp, having bidden a last farewell to the ice. another hour's hard walking brought us to our hotel. no one seeing us crossing the alp would have supposed that we had laid such a day's work behind us; the proximity of home gave vigour to our strides, and our progress was much more speedy than it had been on starting in the morning. i was affectionately welcomed by ramsay, had a warm bath, dined, went to bed, where i lay fast locked in sleep for eight hours, and rose next morning as fresh and vigorous as if i had never scaled the finsteraarhorn. footnotes: [a] the following note describes the single observation made with this thermometer. mr. b. informs me that on finding the instrument bennen swung it in triumph round his head. i fear, therefore, that the observation gives us no certain information regarding the minimum winter-temperature. "st. nicholas, , aug. . "sir,--on tuesday last (the rd inst.) a party, consisting of messrs. b., h., r. l., and myself, succeeded in reaching the summit of the finsteraarhorn under the guidance of bennen and melchior anderegg. we made it an especial object to observe and reset the minimum-thermometer which you left there last year. on reaching the summit, before i had time to stop him, bennen produced the instrument, and it is just possible that in moving it he may have altered the position of the index. however, as he held the instrument horizontally, and did not, as far as i saw, give it any sensible jerk, i have great confidence that the index remained unmoved. "the reading of the index was - ° cent. "a portion of the spirit extending over about - / ° (and standing tween ° and - / °) was separated from the rest, but there appeared to be no data for determining when the separation had taken place. as it appeared desirable to unite the two portions of spirit before again setting the index to record the cold of another winter, we endeavoured to effect this by heating the bulb, but unfortunately, just as we were expecting to see them coalesce, the bulb burst, and i have now to express my great regret that my clumsiness or ignorance of the proper mode of setting the instrument in order should have interfered with the continuance of observations of so much interest. the remains of the instrument, together with a note of the accident, i have left in the charge of wellig, the landlord of the hotel on the Æggischhorn. "we reached the summit about . a.m. and remained there till noon; the reading of a pocket thermometer in the shade was ° f. "should there be any further details connected with our ascent on which you would like to have information, i shall be happy to supply them to the best of my recollection. meanwhile, with a farther apology for my clumsiness, i beg to subscribe myself yours respectfully, "h." "professor tyndall." ( .) [sidenote: a rotating iceberg. .] on the th of august there was a long fight between mist and sunshine, each triumphing by turns, till at length the orb gained the victory and cleansed the mountains from every trace of fog. we descended to the märjelen see, and, wishing to try the floating power of its icebergs, at a place where masses sufficiently large approached near to the shore, i put aside a portion of my clothes, and retaining my boots stepped upon the floating ice. it bore me for a time, and i hoped eventually to be able to paddle myself over the water. on swerving a little, however, from the position in which i first stood, the mass turned over and let me into the lake. i tried a second one, which served me in the same manner; the water was too cold to continue the attempt, and there was also some risk of being unpleasantly ground between the opposing surfaces of the masses of ice. a very large iceberg which had been detached some short time previously from the glacier lay floating at some distance from us. suddenly a sound like that of a waterfall drew our attention towards it. we saw it roll over with the utmost deliberation, while the water which it carried along with it rushed in cataracts down its sides. its previous surface was white, its present one was of a lovely blue, the submerged crystal having now come to the air. the summerset of this iceberg produced a commotion all over the lake; the floating masses at its edge clashed together, and a mellow glucking sound, due to the lapping of the undulations against the frozen masses, continued long afterwards. we subsequently spent several hours upon the glacier; and on this day i noticed for the first time a contemporaneous exhibition of _bedding_ and _structure_ to which i shall refer at another place. we passed finally to the left bank of the glacier, at some distance below the base of the Æggischhorn, and traced its old moraines at intervals along the flanks of the bounding mountain. at the summit of the ridge we found several fine old _roches moutonnées_, on some of which the scratchings of a glacier long departed were well preserved; and from the direction of the scratchings it might be inferred that the ice moved down the mountain towards the valley of the rhone. a plunge into a lonely mountain lake ended the day's excursion. [sidenote: end of the aletsch glacier. .] on the th of august we quitted this noble station. sending our guide on to viesch to take a conveyance and proceed with our luggage down the valley, ramsay and myself crossed the mountains obliquely, desiring to trace the glacier to its termination. we had no path, but it was hardly possible to go astray. we crossed spurs, climbed and descended pleasant mounds, sometimes with the soft grass under our feet, and sometimes knee-deep in rhododendrons. it took us several hours to reach the end of the glacier, and we then looked down upon it merely. it lay couched like a reptile in a wild gorge, as if it had split the mountain by its frozen snout. we afterwards descended to mörill, where we met our guide and driver; thence down the valley to visp; and the following evening saw us lodged at the monte rosa hotel in zermatt. the boiling point of water on the table of the _salle à manger_, i found to be . ° fahr. [sidenote: meadows invaded by ice. .] on the following morning i proceeded without my friend to the görner glacier. as is well known, the end of this glacier has been steadily advancing for several years, and when i saw it, the meadow in front of it was partly shrivelled up by its irresistible advance. i was informed by my host that within the last sixty years forty-four chalets had been overturned by the glacier, the ground on which they stood being occupied by the ice; at present there are others for which a similar fate seems imminent. in thus advancing the glacier merely takes up ground which belonged to it in former ages, for the rounded rocks which rise out of the adjacent meadow show that it once passed over them. i had arranged to meet ramsay this morning on the road to the riffelberg. the meeting took place, but i then learned that a minute or two after my departure he had received intelligence of the death of a near relative. thus was our joint expedition terminated, for he resolved to return at once to england. at my solicitation he accompanied me to the riffel hotel. we had planned an ascent of monte rosa together, but the arrangement thus broke down, and i was consequently thrown upon my own resources. lauener had never made the ascent, but he nevertheless felt confident that we should accomplish it together. first ascent of monte rosa, . ( .) [sidenote: the riffelberg. .] [sidenote: sounds on the glacier. .] on monday, the th of august, we reached the riffel, and, by good fortune, on the evening of the same day, my guide's brother, the well-known ulrich lauener, also arrived at the hotel on his return from monte rosa. from him we obtained all the information possible respecting the ascent, and he kindly agreed to accompany us a little way the next morning, to put us on the right track. at three a.m. the door of my bedroom opened, and christian lauener announced to me that the weather was sufficiently good to justify an attempt. the stars were shining overhead; but ulrich afterwards drew our attention to some heavy clouds which clung to the mountains on the other side of the valley of the visp; remarking that the weather _might_ continue fair throughout the day, but that these clouds were ominous. at four o'clock we were on our way, by which time a gray stratus cloud had drawn itself across the neck of the matterhorn, and soon afterwards another of the same nature encircled his waist. we proceeded past the riffelhorn to the ridge above the görner glacier, from which monte rosa was visible from top to bottom, and where an animated conversation in swiss patois commenced. ulrich described the slopes, passes, and precipices, which were to guide us; and christian demanded explanations, until he was finally able to declare to me that his knowledge was sufficient. we then bade ulrich good-bye, and went forward. all was clear about monte rosa, and the yellow morning light shone brightly upon its uppermost snows. beside the queen of the alps was the huge mass of the lyskamm, with a saddle stretching from the one to the other; next to the lyskamm came two white rounded mounds, smooth and pure, the twins castor and pollux, and further to the right again the broad brown flank of the breithorn. behind us mont cervin gathered the clouds more thickly round him, until finally his grand obelisk was totally hidden. we went along the mountain-side for a time, and then descended to the glacier. the surface was hard frozen, and the ice crunched loudly under our feet. there was a hollowness and volume in the sound which require explanation; and this, i think, is furnished by the remarks of sir john herschel on those hollow sounds at the solfaterra, near naples, from which travellers have inferred the existence of cavities within the mountain. at the place where these sounds are heard the earth is friable, and, when struck, the concussion is reinforced and lengthened by the partial echoes from the surfaces of the fragments. the conditions for a similar effect exist upon the glacier, for the ice is disintegrated to a certain depth, and from the innumerable places of rupture little reverberations are sent, which give a length and hollowness to the sound produced by the crushing of the fragments on the surface. we looked to the sky at intervals, and once a meteor slid across it, leaving a train of sparks behind. the blue firmament, from which the stars shone down so brightly when we rose, was more and more invaded by clouds, which advanced upon us from our rear, while before us the solemn heights of monte rosa were bathed in rich yellow sunlight. as the day advanced the radiance crept down towards the valleys; but still those stealthy clouds advanced like a besieging army, taking deliberate possession of the summits, one after the other, while gray skirmishers moved through the air above us. the play of light and shadow upon monte rosa was at times beautiful, bars of gloom and zones of glory shifting and alternating from top to bottom of the mountain. [sidenote: advance of the clouds. .] at five o'clock a gray cloud alighted on the shoulder of the lyskamm, which had hitherto been warmed by the lovely yellow light. soon afterwards we reached the foot of monte rosa, and passed from the glacier to a slope of rocks, whose rounded forms and furrowed surfaces showed that the ice of former ages had moved over them; the granite was now coated with lichens, and between the bosses where mould could rest were patches of tender moss. as we ascended, a peal to the right announced the descent of an avalanche from the twins; it came heralded by clouds of ice-dust, which resembled the sphered masses of condensed vapour which issue from a locomotive. a gentle snow-slope brought us to the base of a precipice of brown rocks, round which we wound; the snow was in excellent order, and the chasms were so firmly bridged by the frozen mass that no caution was necessary in crossing them. surmounting a weathered cliff to our left, we paused upon the summit to look upon the scene around us. the snow gliding insensibly from the mountains, or discharged in avalanches from the precipices which it overhung, filled the higher valleys with pure white glaciers, which were rifted and broken here and there, exposing chasms and precipices from which gleamed the delicate blue of the half-formed ice. sometimes, however, the _névés_ spread over wide spaces without a rupture or wrinkle to break the smoothness of the superficial snow. the sky was now for the most part overcast, but through the residual blue spaces the sun at intervals poured light over the rounded bosses of the mountain. [sidenote: monte rosa capped. .] at half-past seven o'clock we reached another precipice of rock, to the left of which our route lay, and here lauener proposed to have some refreshment; after which we went on again. the clouds spread more and more, leaving at length mere specks and patches of blue between them. passing some high peaks, formed by the dislocation of the ice, we came to a place where the _névé_ was rent by crevasses, on the walls of which the stratification due to successive snow-falls was shown with great beauty and definition. between two of these fissures our way now lay: the wall of one of them was hollowed out longitudinally midway down, thus forming a roof above and a ledge below, and from roof to ledge stretched a railing of cylindrical icicles, as if intended to bolt them together. a cloud now for the first time touched the summit of monte rosa, and sought to cling to it, but in a minute it dispersed in shattered fragments, as if dashed to pieces for its presumption. the mountain remained for a time clear and triumphant, but the triumph was short-lived: like suitors that will not be repelled, the dusky vapours came; repulse after repulse took place, and the sunlight gushed down upon the heights, but it was manifest that the clouds gained ground in the conflict. until about a quarter past nine o'clock our work was mere child's play, a pleasant morning stroll along the flanks of the mountain; but steeper slopes now rose above us, which called for more energy, and more care in the fixing of the feet. looked at from below, some of these slopes appeared precipitous; but we were too well acquainted with the effect of fore-shortening to let this daunt us. at each step we dug our bâtons into the deep snow. when first driven in, the bâtons[a] _dipped_ from us, but were brought, as we walked forward, to the vertical, and finally beyond it at the other side. the snow was thus forced aside, a rubbing of the staff against it, and of the snow-particles against each other, being the consequence. we had thus perpetual rupture and regelation; while the little sounds consequent upon rupture, reinforced by the partial echoes from the surfaces of the granules, were blended together to a note resembling the lowing of cows. hitherto i had paused at intervals to make notes, or to take an angle; but these operations now ceased, not from want of time, but from pure dislike; for when the eye has to act the part of a sentinel who feels that at any moment the enemy may be upon him; when the body must be balanced with precision, and legs and arms, besides performing actual labour, must be kept in readiness for possible contingencies; above all, when you feel that your safety depends upon yourself alone, and that, if your footing gives way, there is no strong arm behind ready to be thrown between you and destruction; under such circumstances the relish for writing ceases, and you are willing to hand over your impressions to the safe keeping of memory. [sidenote: the "comb" of the mountain. .] [sidenote: ascent along a cornice. .] from the vast boss which constitutes the lower portion of monte rosa cliffy edges run upwards to the summit. were the snow removed from these we should, i doubt not, see them as toothed or serrated crags, justifying the term "_kamm_," or "comb," applied to such edges by the germans. our way now lay along such a kamm, the cliffs of which had, however, caught the snow, and been completely covered by it, forming an edge like the ridge of a house-roof, which sloped steeply upwards. on the lyskamm side of the edge there was no footing, and, if a human body fell over here, it would probably pass through a vertical space of some thousands of feet, falling or rolling, before coming to rest. on the other side the snow-slope was less steep, but excessively perilous-looking, and intersected by precipices of ice. dense clouds now enveloped us, and made our position far uglier than if it had been fairly illuminated. the valley below us was one vast cauldron, filled with precipitated vapour, which came seething at times up the sides of the mountain. sometimes this fog would partially clear away, and the light would gleam upwards from the dislocated glaciers. my guide continually admonished me to make my footing sure, and to fix at each step my staff firmly in the consolidated snow. at one place, for a short steep ascent, the slope became hard ice, and our position a very ticklish one. we hewed our steps as we moved upwards, but were soon glad to deviate from the ice to a position scarcely less awkward. the wind had so acted upon the snow as to fold it over the edge of the kamm, thus causing it to form a kind of cornice, which overhung the precipice on the lyskamm side of the mountain. this cornice now bore our weight: its snow had become somewhat firm, but it was yielding enough to permit the feet to sink in it a little way, and thus secure us at least against the danger of slipping. here also at each step we drove our bâtons firmly into the snow, availing ourselves of whatever help they could render. once, while thus securing my anchorage, the handle of my hatchet went right through the cornice on which we stood, and, on withdrawing it, i could see through the aperture into the cloud-crammed gulf below. we continued ascending until we reached a rock protruding from the snow, and here we halted for a few minutes. lauener looked upwards through the fog. "according to all description," he observed, "this ought to be the last kamm of the mountain; but in this obscurity we can see nothing." snow began to fall, and we recommenced our journey, quitting the rocks and climbing again along the edge. another hour brought us to a crest of cliffs, at which, to our comfort, the kamm appeared to cease, and other climbing qualities were demanded of us. [sidenote: "die hÖchste spitze." .] on the lyskamm side, as i have said, rescue would be out of the question, should the climber go over the edge. on the other side of the edge rescue seemed possible, though the slope, as stated already, was most dangerously steep. i now asked lauener what he would have done, supposing my footing to have failed on the latter slope. he did not seem to like the question, but said that he should have considered well for a moment and then have sprung after me; but he exhorted me to drive all such thoughts away. i laughed at him, and this did more to set his mind at rest than any formal profession of courage could have done. we were now among rocks: we climbed cliffs and descended them, and advanced sometimes with our feet on narrow ledges, holding tightly on to other ledges by our fingers; sometimes, cautiously balanced, we moved along edges of rock with precipices on both sides. once, in getting round a crag, lauener shook a book from his pocket; it was arrested by a rock about sixty or eighty feet below us. he wished to regain it, but i offered to supply its place, if he thought the descent too dangerous. he said he would make the trial, and parted from me. i thought it useless to remain idle. a cleft was before me, through which i must pass; so, pressing my knees and back against its opposite sides, i gradually worked myself to the top. i descended the other face of the rock, and then, through a second ragged fissure, to the summit of another pinnacle. the highest point of the mountain was now at hand, separated from me merely by a short saddle, carved by weathering out of the crest of the mountain. i could hear lauener clattering after me, through the rocks behind. i dropped down upon the saddle, crossed it, climbed the opposite cliff, and "_die höchste spitze_" of monte rosa was won. [sidenote: gloom on the summit. .] lauener joined me immediately, and we mutually congratulated each other on the success of the ascent. the residue of the bread and meat was produced, and a bottle of tea was also appealed to. mixed with a little cognac, lauener declared that he had never tasted anything like it. snow fell thickly at intervals, and the obscurity was very great; occasionally this would lighten and permit the sun to shed a ghastly dilute light upon us through the gleaming vapour. i put my boiling-water apparatus in order, and fixed it in a corner behind a ledge; the shelter was, however, insufficient, so i placed my hat above the vessel. the boiling point was . ° fahr., the ledge on which the instrument stood being feet below the highest point of the mountain. the ascent from the riffel hotel occupied us about seven hours, nearly two of which were spent upon the kamm and crest. neither of us felt in the least degree fatigued; i, indeed, felt so fresh, that had another monte rosa been planted on the first, i should have continued the climb without hesitation, and with strong hopes of reaching the top. i experienced no trace of mountain sickness, lassitude, shortness of breath, heart-beat, or headache; nevertheless the summit of monte rosa is , feet high, being less than feet lower than mont blanc. it is, i think, perfectly certain, that the rarefaction of the air at this height is not sufficient of itself to produce the symptoms referred to; physical exertion must be superadded. [sidenote: "frozen flowers." .] after a few fitful efforts to dispel the gloom, the sun resigned the dominion to the dense fog and the descending snow, which now prevented our seeing more than or paces in any direction. the temperature of the crags at the summit, which had been shone upon by the unclouded sun during the earlier portion of the day, was ° fahr.; hence the snow melted instantly wherever it came in contact with the rock. but some of it fell upon my felt hat, which had been placed to shelter the boiling-water apparatus, and this presented the most remarkable and beautiful appearance. the fall of snow was in fact a shower of frozen flowers. all of them were six-leaved; some of the leaves threw out lateral ribs like ferns, some were rounded, others arrowy and serrated, some were close, others reticulated, but there was no deviation from the six-leaved type. nature seemed determined to make us some compensation for the loss of all prospect, and thus showered down upon us those lovely blossoms of the frost; and had a spirit of the mountain inquired my choice, the view, or the frozen flowers, i should have hesitated before giving up that exquisite vegetation. it was wonderful to think of, as well as beautiful to behold. let us imagine the eye gifted with a microscopic power sufficient to enable it to see the molecules which composed these starry crystals; to observe the solid nucleus formed and floating in the air; to see it drawing towards it its allied atoms, and these arranging themselves as if they moved to music, and ended by rendering that music concrete. surely such an exhibition of power, such an apparent demonstration of a resident intelligence in what we are accustomed to call "brute matter," would appear perfectly miraculous. and yet the reality would, if we could see it, transcend the fancy. if the houses of parliament were built up by the forces resident in their own bricks and lithologic blocks, and without the aid of hodman or mason, there would be nothing intrinsically more wonderful in the process than in the molecular architecture which delighted us upon the summit of monte rosa. [sidenote: startling avalanche. .] twice or thrice had my guide warned me that we must think of descending, for the snow continued to fall heavily, and the loss of our track would be attended with imminent peril. we therefore packed up, and clambered downward among the crags of the summit. we soon left these behind us, and as we stood once more upon the kamm, looking into the gloom beneath, an avalanche let loose from the side of an adjacent mountain shook the air with its thunder. we could not see it, could form no estimate of its distance, could only hear its roar, which coming to us through the darkness, had an undefinable element of horror in it. lauener remarked, "i never hear those things without a shudder; the memory of my brother comes back to me at the same time." his brother, who was the best climber in the oberland, had been literally broken to fragments by an avalanche on the slopes of the jungfrau. we had been separate coming up, each having trusted to himself, but the descent was more perilous, because it is more difficult to fix the heel of the boot than the toe securely in the ice. lauener was furnished with a rope, which he now tied round my waist, and forming a noose at the other end, he slipped it over his arm. this to me was a new mode of attachment. hitherto my guides in dangerous places had tied the ropes round _their_ waists also. simond had done it on mont blanc, and bennen on the finsteraarhorn, proving thus their willingness to share my fate whatever that might be. but here lauener had the power of sending me adrift at any moment, should his own life be imperilled. i told him that his mode of attachment was new to me, but he assured me that it would give him more power in case of accident. i did not see this at the time; but neither did i insist on his attaching himself in the usual way. it could neither be called anger nor pride, but a warm flush ran through me as i remarked, that i should take good care not to test his power of holding me. i believe i wronged my guide by the supposition that he made the arrangement with reference to his own safety, for all i saw of him afterwards proved that he would at any time have risked his life to save mine. the flush however did me good, by displacing every trace of anxiety, and the rope, i confess, was also a source of some comfort to me. we descended the kamm, i going first. "secure your footing before you move," was my guide's constant exhortation, "and make your staff firm at each step." we were sometimes quite close upon the rim of the kamm on the lyskamm side, and we also followed the depressions which marked our track along the cornice. this i now tried intentionally, and drove the handle of my axe through it once or twice. at two places in descending we were upon the solid ice, and these were some of the steepest portions of the kamm. they were undoubtedly perilous, and the utmost caution was necessary in fixing the staff and securing the footing. these however once past, we felt that the chief danger was over. we reached the termination of the edge, and although the snow continued to fall heavily, and obscure everything, we knew that our progress afterwards was secure. there was pleasure in this feeling; it was an agreeable variation of that grim mental tension to which i had been previously wound up, but which in itself was by no means disagreeable. [sidenote: splendid blue of the snow. .] [sidenote: stifling heat. .] i have already noticed the colour of the fresh snow upon the summit of the stelvio pass. since i observed it there it has been my custom to pay some attention to this point at all great elevations. this morning, as i ascended monte rosa, i often examined the holes made in the snow by our bâtons, but the light which issued from them was scarcely perceptibly blue. now, however, a deep layer of fresh snow overspread the mountain, and the effect was magnificent. along the kamm i was continually surprised and delighted by the blue gleams which issued from the broken or perforated stratum of new snow; each hole made by the staff was filled with a light as pure, and nearly as deep, as that of the unclouded firmament. when we reached the bottom of the kamm, lauener came to the front, and tramped before me. as his feet rose out of the snow, and shook the latter off in fragments, sudden and wonderful gleams of blue light flashed from them. doubtless the blue of the sky has much to do with mountain colouring, but in the present instance not only was there no blue sky, but the air was so thick with fog and descending snow-flakes, that we could not see twenty yards in advance of us. a thick fog, which wrapped the mountain quite closely, now added its gloom to the obscurity caused by the falling snow. before we reached the base of the mountain the fog became thin, and the sun shone through it. there was not a breath of air stirring, and, though we stood ankle-deep in snow, the heat surpassed anything of the kind i had ever felt: it was the dead suffocating warmth of the interior of an oven, which encompassed us on all sides, and from which there seemed no escape. our own motion through the air, however, cooled us considerably. we found the snow-bridges softer than in the morning, and consequently needing more caution; but we encountered no real difficulty among them. indeed it is amusing to observe the indifference with which a snow-roof is often broken through, and a traveller immersed to the waist in the jaws of a fissure. the effort at recovery is instantaneous; half instinctively hands and knees are driven into the snow, and rescue is immediate. fair glacier work was now before us; after which we reached the opposite mountain-slope, which we ascended, and then went down the flank of the riffelberg to our hotel. the excursion occupied us eleven and a half hours. footnotes: [a] my staff was always the handle of an axe an inch or two longer than an ordinary walking-stick. ( .) on the afternoon of the th i made an attempt alone to ascend the riffelhorn, and attained a considerable height; but i attacked it from the wrong side, and the fading light forced me to retreat. i found some agreeable people at the hotel on my return. one clergyman especially, with a clear complexion, good digestion, and bad lungs--of free, hearty, and genial manner--made himself extremely pleasant to us all. he appeared to bubble over with enjoyment, and with him and others on the morning of the th i walked to the görner grat, as it lay on the way to my work. we had a glorious prospect from the summit: indeed the assemblage of mountains, snow, and ice, here within view is perhaps without a rival in the world.[a] i shouldered my axe, and saying "good-bye" moved away from my companions. "are you going?" exclaimed the clergyman. "give me one grasp of your hand before we part." this was the signal for a grasp all round; and the hearty human kindness which thus showed itself contributed that day to make my work pleasant to me. [sidenote: a difficult descent. .] we proceeded along the ridge of the rothe kumme to a point which commanded a fine view of the glacier. the ice had been over these heights in ages past, for, although lichens covered the surfaces of the old rocks, they did not disguise the grooves and scratchings. the surface of the glacier was now about a thousand feet below us, and this it was our desire to attain. to reach it we had to descend a succession of precipices, which in general were weathered and rugged, but here and there, where the rock was durable, were fluted and grooved. once or twice indeed we had nothing to cling to but the little ridges thus formed. we had to squeeze ourselves through narrow fissures, and often to get round overhanging ledges, where our main trust was in our feet, but where these had only ledges an inch or so in width to rest upon. these cases were to me the most unpleasant of all, for they compelled the arms to take a position which, if the footing gave way, would necessitate a _wrench_, for which i entertain considerable abhorrence. we came at length to a gorge by which the mountain is rent from top to bottom, and into which we endeavoured to descend. we worked along its rim for a time, but found its smooth faces too deep. we retreated; lauener struck into another track, and while he tested it i sat down near some grass tufts, which flourished on one of the ledges, and found the temperature to be as follows:-- temperature of rock ° c. of air an inch above the rock of air a foot from rock of grass the first of these numbers does not fairly represent the temperature of the rock, as the thermometer could be in contact with it only at one side at a time. it was differences such as these between grass and stone, producing a mixed atmosphere of different densities, that weakened the sound of the falls of the orinoco, as observed and explained by humboldt. [sidenote: singular ice-cave. .] by a process of "trial and error" we at length reached the ice, after two hours had been spent in the effort to disentangle ourselves from the crags. the glacier is forcibly thrust at this place against the projecting base of the mountain, and the structure of the ice correspondingly developed. crevasses also intersect the ice, and the blue veins cross them at right angles. i ascended the glacier to a region where the ice was compressed and greatly contorted, and thought that in some cases i could see the veins crossing the lines of stratification. once my guide drew my attention to what he called "_ein sonderbares loch_." on one of the slopes an archway was formed which appeared to lead into the body of the glacier. we entered it, and explored the cavern to its end. the walls were of transparent blue ice, singularly free from air-bubbles; but where the roof of the cavern was thin enough to allow the sun to shine feebly through it, the transmitted light was of a pink colour. my guide expressed himself surprised at "_den röthlichen schein_." at one place a plate of ice had been placed like a ceiling across the cavern; but owing to lateral squeezing it had been broken so as to form a v. i found some air-bubbles in this ice, and in all cases they were associated with blebs of water. a portion of the "ceiling," indeed, was very full of bubbles, and was at some places reduced, by internal liquefaction, to a mere skeleton of ice, with water-cells between its walls. [sidenote: structure and strata. .] high up the glacier (towards the old weissthor) the horizontal stratification is everywhere beautifully shown. i drew my guide's attention to it, and he made the remark that the perfection of the lower ice was due to the pressure of the layers above it. "the snow by degrees compressed itself to glacier." as we approached one of the tributaries on the monte rosa side, where great pressure came into play, the stratification appeared to yield and the true structure to cross it at those places where it had yielded most. as the place of greatest pressure was approached, the bedding disappeared more and more, and a clear vertical structure was finally revealed. footnotes: [a] in mr. e. w. cooke made a pencil-sketch of this splendid panorama, which is the best and truest that i have yet seen. the gÖrner grat and the riffelhorn. magnetic phenomena. ( .) at an early hour on saturday, the th of august, i heard the servant exclaim, "_das wetter ist wunderschön!_" which good news caused me to spring from my bed and prepare to meet the morn. the range of summits at the opposite side of the valley of st. nicholas was at first quite clear, but as the sun ascended light cumuli formed round them, increasing in density up to a certain point; below these clouds the air of the valley was transparent; above them the air of heaven was still more so; and thus they swung midway between heaven and earth, ranging themselves in a level line along the necks of the mountains. [sidenote: generation of clouds. .] it might be supposed that the presence of the sun heating the air would tend to keep it more transparent, by increasing its capacity to dissolve all visible cloud; and this indeed is the true action of the sun. but it is not the only action. his rays, as he climbed the eastern heaven, shot more and more deeply into the valley of st. nicholas, the moisture of which rose as invisible vapour, remaining unseen as long as the air possessed sufficient warmth to keep it in the vaporous state. high up, however, the cold crags which had lost their heat by radiation the night before, acted like condensers upon the ascending vapour, and caused it to curdle into visible fog. the current, however, continued ascensional, and the clouds were slowly lifted above the tallest peaks, where they arranged themselves in fantastic forms, shifting and changing shape as they gradually melted away. one peak stood like a field-officer with his cap raised above his head, others sent straggling cloud-balloons upwards; but on watching these outliers they were gradually seen to disappear. at first they shone like snow in the sunlight, but as they became more attenuated they changed colour, passing through a dull red to a dusky purple hue, until finally they left no trace of their existence. [sidenote: the rocks warmed. .] [sidenote: scene from the gÖrner grat. .] as the day advanced, warming the rocks, the clouds wholly disappeared, and a hyaline air formed the setting of both glaciers and mountains. i climbed to the görner grat to obtain a general view of the surrounding scene. looking towards the origin of the görner glacier the view was bounded by a wide col, upon which stood two lovely rounded eminences enamelled with snow of perfect purity. they shone like burnished silver in the sunlight, as if their surfaces had been melted and recongealed to frosted mirrors from which the rays were flung. to the right of these were the bounding crags of monte rosa, and then the body of the mountain itself, with its crest of crag and coat of snows. to the right of monte rosa, and almost rivalling it in height, was the vast mass of the lyskamm, a rough and craggy mountain, to whose ledges clings the snow which cannot grasp its steeper walls, sometimes leaning over them in impending precipices, which often break, and send wild avalanches into the space below. between the lyskamm and monte rosa lies a large wide valley into which both mountains pour their snows, forming there the western glacier of monte rosa[a]--a noble ice stream, which from its magnitude and permanence deserves to impose its name upon the trunk glacier. it extends downwards from the col which unites the two mountains; riven and broken at some places, but at others stretching white and pure down to its snow-line, where the true glacier emerges from the _névé_. from the rounded shoulders of the twin castor a glacier descends, at first white and shining, then suddenly broken into faults, fissures, and precipices, which are afterwards repaired, and the glacier joins that of monte rosa before the junction of the latter with the trunk stream. next came a boss of rock, with a secondary glacier clinging to it as if plastered over it, and after it the schwarze glacier, bounded on one side by the breithorn, and on the other by the twin pollux. this glacier is of considerable magnitude. over its upper portion rise the twin eminences, pure and white; then follows a smooth and undulating space, after passing which the _névé_ is torn up into a collection of peaks and chasms; these, however, are mended lower down, and the glacier moves smoothly and calmly to meet its brothers in the main valley. next comes the trifti glacier,[b] embraced on all sides by the rocky arms of the breithorn; its mass is not very great, but it descends in a graceful sweep, and exhibits towards its extremity a succession of beautiful bands. afterwards we have the glacier of the petit mont cervin and those of st. théodule, which latter are the last that empty their frozen cargoes into the valley of the görner. all the glaciers here mentioned are welded together to a common trunk which squeezes itself through the narrow defile at the base of the riffelhorn. soon afterwards the moraines become confused, the glacier drops steeply to its termination, and ploughs up the meadows in front of it with its irresistible share. in a line with the riffelhorn, and rising over the latter so high as to make it almost vanish by comparison, was the titan obelisk of the matterhorn, from the base of which the furgge glacier struggles downwards. on the other side are the zmutt glacier, the schönbühl, and the hochwang, from the dent blanche; the gabelhorn and trift glaciers, from the summits which bear those names. then come the glaciers of the weisshorn. describing a curve still farther to the right we alight on the peaks of the mischabel, dark and craggy precipices from this side, though from the Æggischhorn they appear as cones of snow. sweeping by the alphubel, the allaleinhorn, the rympfischorn, and strahlhorn--all of them majestic--we reach the pass of the weissthor, and the cima di jazzi. this completes the glorious circuit within the observer's view. [sidenote: compass at fault. .] i placed my compass upon a piece of rock to find the bearing of the görner glacier, and was startled at seeing the sun and it at direct variance. what the sun declared to be north, the needle affirmed to be south. i at first supposed that the maker had placed the s where the n ought to be, and _vice versâ_. on shifting my position, however, the needle shifted also, and i saw immediately that the effect was due to the rock of the grat. sometimes one end of the needle _dipped_ forcibly, at other places it whirled suddenly round, indicating an entire change of polarity. the rock was evidently to be regarded as an assemblage of magnets, or as a single magnet full of "consequent points." a distance of transport not exceeding an inch was, in some cases, sufficient to reverse the position of the needle. i held the needle between the two sides of a long fissure a foot wide. the needle set _along_ the fissure at some places, while at others it set _across_ it. sometimes a little jutting knob would attract the north end of the needle, while a closely adjacent little knob would forcibly repel it, and attract the south end. one extremity of a ledge three feet long was north magnetic, the other end was south magnetic, while a neutral point existed midway between the two, the ledge having therefore the exact polar arrangement of an ordinary bar-magnet. at the highest point of the rock the action appeared to be most intense, but i also found an energetic polarity in a mass at some distance below the summit. [sidenote: magnetism of rocks. .] remembering that professor forbes had noticed some peculiar magnetic effect upon the riffelhorn, i resolved to ascend it. descending from the grat we mounted the rocks which form the base of the horn; these are soft and soapy from the quantity of mica which they contain; the higher rocks of the horn are, however, very dense and hard. the ascent is a pleasant bit of mountain practice. we climbed the walls of rock, and wound round the ledges, seeking the assailable points. i tried the magnetic condition of the rocks as we ascended, and found it in general feeble. in other respects the riffelhorn is a most remarkable mass. the ice of the görner glacier of former ages, which rose hundreds, perhaps thousands of feet above its present level, encountered the horn in its descent, and was split by the latter, a diversion of the ice along the sides of the peak being the consequence. portions of the vertical walls of the horn are polished by this action as if they had come from the hands of a lapidary, and the scratchings are as sharp and definite as if drawn by points of steel. i never saw scratchings so perfectly preserved: the finest lines are as clear as the deepest, a consequence of the great density and durability of the rock. the latter evidently contains a good deal of iron, and its surface near the summit is of the rich brown red due to the peroxide of the metal. when we fairly got among the precipices we left our hatchets behind us, trusting subsequently to our hands and feet alone. squeezing, creeping, clinging, and climbing, in due time we found ourselves upon the summit of the horn. [sidenote: ascent of the riffelhorn. .] a pile of stones had been erected near the point where we gained the top. i examined the stones of this pile, and found them strongly polar. the surrounding rocks also showed a violent action, the needle oscillating quickly, and sometimes twirling swiftly round upon a slight change of position. the fragments of rock scattered about were also polar. long ledges showed north magnetism for a considerable length, and again for an equal length south magnetism. two parallel masses separated from each other by a fissure, showed the same magnetic distribution. while i was engaged at one end of the horn, lauener wandered to the other, on which stood two or three _hommes de pierres_. he was about disturbing some of the stones, when a yell from me surprised him. in fact, the thought had occurred to me that the magnetism of the horn had been developed by lightning striking upon it, and my desire was to examine those points which were most exposed to the discharge of the atmospheric electricity; hence my shout to my guide to let the stones alone. i worked towards the other end of the horn, examining the rocks in my way. two weathered prominences, which seemed very likely recipients of the lightning, acted violently upon the needle. i sometimes descended a little way, and found that among the rocks below the summit the action was greatly enfeebled. on reaching another very prominent point, i found its extremity all north polar, but at a little distance was a cluster of consequent points, among which the transport of a few inches was sufficient to turn the needle round and round. [sidenote: magnetism of the horn. .] the piles of stone at the zermatt end of the horn did not seem so strongly polar as the pile at the other end, which was higher; still a strong polar action was manifested at many points of the surrounding rocks. having completed the examination of the summit, i descended the horn, and examined its magnetic condition as i went along. it seemed to me that the jutting prominences always exhibited the strongest action. i do not indeed remember any case in which a strong action did not exhibit itself at the ends of the terraces which constitute the horn. in all cases, however, the rock acted as a number of magnets huddled confusedly together, and not as if its entire mass was endowed with magnetism of one kind. [illustration: fig. . magnetic boulder of the riffelhorn.] on the evening of the same day i examined the lower spur of the riffelhorn. amid its fissures and gullies one feels as if wandering through the ruins of a vast castle or fortification; the precipices are so like walls, and the scratching and polishing so like what might be done by the hands of man. i found evidences of strong polar action in some of the rocks low down. in the same continuous mass the action would sometimes exhibit itself over an area of small extent, while the remainder of the rock showed no appreciable action. some of the boulders cast down from the summit exhibited a strong and varied polarity. fig. is a sketch of one of these; the barbed end of each arrow represents the north end of the needle, which assumed the various positions shown in the figure. midway down the spur i lighted upon a transverse wall of rock, which formed in earlier ages the boundary of a lateral outlet of the görner glacier. it was red and hard, weathered rough at some places, and polished smooth at others. the lines were drawn finely upon it, but its outer surface appeared to be peeling off like a crust; the polished layer rested upon the rock like a kind of enamel. the action of the glacier appeared to resemble that of the break of a locomotive upon rails, both being cases of exfoliation brought about by pressure and friction. this wall measured twenty-eight yards across, and one end of it, for a distance of ten or twelve yards, was all north polar; the other end for a similar distance was south polar, but there was a pair of consequent points at its centre. [sidenote: the magnetic force. .] to meet the case of my young readers, i will here say a few words about the magnetic force. the common magnetic needle points nearly north and south; and if a bit of iron be brought near to either end of the needle, they will mutually attract each other. a piece of lead will not show this effect, nor will copper, gold, nor silver. iron, in fact, is a magnetic metal, which the others are not. it is to be particularly observed, that the bit of iron attracts _both ends_ of the needle when it is presented to them in succession; and if a common steel sewing needle be substituted for the iron it will be seen that it also has the power of attracting both ends of the magnetic needle. but if the needle be rubbed once or twice along one end of a magnet, it will be found that one of its ends will afterwards _repel_ a certain end of the magnetic needle and attract the other. by rubbing the needle on the magnet, we thus develop both attraction and repulsion, and this double action of the magnetic force is called its _polarity_; thus the steel which was at first simply _magnetic_, is now magnetic and _polar_. it is the aim of persons making magnets, that each magnet should have but _two_ poles, at its two ends; it is, however, easy to develop in the same piece of steel several pairs or poles; and if the magnetization be irregular, this is sometimes done when we wish to avoid it. these irregular poles are called _consequent points_. now i want my young reader to understand that it is not only because the rocks of the görner grat and riffelhorn contain iron, that they exhibit the action which i have described. they are not only magnetic, as common iron is, but, like the magnetized steel needle, they are magnetic and polar. and these poles are irregularly distributed like the "consequent points" to which i have referred, and this is the reason why i have used the term. [sidenote: bearings from the riffelhorn. .] professor forbes, as i have already stated, was the first to notice the effect of the riffelhorn upon the magnetic needle, but he seems to have supposed that the entire mass of the mountain exercised "a local attraction" upon the needle; (upon which end he does not say). to enable future observers to allow for this attraction, he took the bearing of several of the surrounding mountains from the riffelhorn; but it is very probable that had he changed his position a few inches, and perfectly certain had he changed it a few yards, he would have found a set of bearings totally different from those which he has recorded. the close proximity and irregular distribution of its consequent points would prevent the riffelhorn from exerting any appreciable influence on _a distant needle_, as in this case the local poles would effectually neutralize each other. footnotes: [a] now called, in the federal map, the 'grenz glacier.'--l. c. t. [b] i take this name from studer's map. sometimes, however, i have called it the "breithorn glacier." ( .) [sidenote: mont cervin as cloud-maker. .] on the morning of the th the riffelberg was swathed in a dense fog, through which heavy rain showered incessantly. towards one o'clock the continuity of the gray mass was broken, and sky-gleams of the deepest blue were seen through its apertures; these would close up again, and others open elsewhere, as if the fog were fighting for existence with the sun behind it. the sun, however, triumphed, the mountains came more and more into view, and finally the entire air was swept clear. i went up to the görner grat in the afternoon, and examined more closely the magnetism of its rocks; here, as on the riffelhorn, i found it most pronounced at the jutting prominences of the grat. can it be that the superior exposure is more favourable to the formation of the magnetic oxide of iron? i secured a number of fragments, which i still possess, and which act forcibly upon a magnetic needle. the sun was near the western horizon, and i remained alone upon the grat to see his last beams illuminate the mountains, which, with one exception, were without a trace of cloud. this exception was the matterhorn, the appearance of which was extremely instructive. the obelisk appeared to be divided in two halves by a vertical line drawn from its summit half way down, to the windward of which we had the bare cliffs of the mountain; and to the left of it a cloud which appeared to cling tenaciously to the rocks. in reality, however, there was no clinging; the condensed vapour incessantly got away, but it was ever renewed, and thus a river of cloud had been sent from the mountain over the valley of aosta. the wind in fact blew lightly up the valley of st. nicholas charged with moisture, and when the air that held it rubbed against the cold cone of the matterhorn the vapour was chilled and precipitated in his lee. the summit seemed to smoke sometimes like a burning mountain; for immediately after its generation, the fog was drawn away in long filaments by the wind. as the sun sank lower the ruddiness of his light augmented, until these filaments resembled streamers of flame. the sun sank deeper, the light was gradually withdrawn, and where it had entirely vanished it left the mountain like a desolate old man whose "hoary hair stream'd like a meteor in the troubled air." for a moment after the sun had disappeared the scene was amazingly grand. the distant west was ruddy, copious gray smoke-wreaths were wafted from the mountains, while high overhead, in an atmospheric region which seemed perfectly motionless, floated a broad thin cloud, dyed with the richest iridescences. the colours were of the same character as those which i had seen upon the aletschhorn, being due to interference, and in point of splendour and variety far exceeded anything ever produced by the mere coloured light of the setting sun. [sidenote: cells in the ice. .] on the th i was early upon the glacier. it had frozen hard during the night, and the partially liberated streams flowed, in many cases, over their own ice. i took some clear plates from under the water, and found in them numerous liquid cells, each associated with an air-bubble or a vacuous spot. the most common shape of the cells was a regular hexagon, but there were all forms between the perfect hexagon and the perfect circle. many cells had also crimped borders, intimating that their primitive form was that of a flower with six leaves. a plate taken from ice which was defended from the sunbeams by the shadow of a rock had no such cells; so that those that i observed were probably due to solar radiation. my first aim was to examine the structure of the görnerhorn glacier,[a] which descends the breast of monte rosa until it is abruptly cut off by the great western glacier of the mountain.[b] between them is a moraine which is at once terminal as regards the former, and lateral as regards the latter. the ice is veined vertically along the moraine, the direction of the structure being parallel to the latter. i ascended the glacier, and found, as i retreated from the place where the thrust was most violent, that the structure became more feeble. from the glacier i passed to the rocks called "_auf der platte_," so as to obtain a general view of its terminal portion. the gradual perfecting of the structure as the region of pressure was approached was very manifest: the ice at the end seemed to wrinkle up in obedience to the pressure, the structural furrows, from being scarcely visible, became more and more decided, and the lamination underneath correspondingly pronounced, until it finally attained a state of great perfection. [sidenote: structure of the ice. .] i now quitted the rocks and walked straight across the western glacier of monte rosa to its centre, where i found the structure scarcely visible. i next faced the görner grat, and walked down the glacier towards the moraine which divides it from the görner glacier. the mechanical conditions of the ice here are quite evident; each step brought me to a place of greater pressure, and also to a place of more highly developed structure, until finally near to the moraine itself, and running parallel to it, a magnificent lamination was developed. here the superficial groovings could be traced to great distances, and beside the moraine were boulders poised on pedestals of ice through which the blue veins ran. at some places the ice had been weathered into laminæ not more than a line in thickness. i now recrossed the monte rosa glacier to its junction with the schwartze glacier, which descends between the twins and breithorn. the structure of the monte rosa glacier is here far less pronounced than at the other side, and the pressure which it endures is also manifestly less; the structure of the schwartze glacier is fairly developed, being here parallel to its moraine. the cliffs of the breithorn are much exposed to weathering action, and boulders are copiously showered down upon the adjacent ice. between the schwartze glacier and the glacier which descends from the breast of the breithorn itself these blocks ride upon a spine of ice, and form a moraine of grand proportions. from it a fine view of the glacier is attainable, and the gradual development of its structure as the region of maximum pressure is approached is very plain. a number of gracefully curved undulations sweep across the breithorn glacier, which are squeezed more closely together as the moraine is approached. all the glaciers that descend from the flanking mountains of the görner valley are suddenly turned aside where they meet the great trunk stream, and are reduced by the pressure to narrow stripes of ice separated from each other by parallel moraines. [sidenote: tributaries explored. .] i ascended the breithorn glacier to the base of an ice-fall, on one side of which i found large crumples produced by the pressure, the veined structure being developed at right angles to the direction of the latter. no such structure was visible above this place. the crumples were cut by fissures, perpendicular to which the blue veins ran. i now quitted the glacier, and clambered up the adjacent alp, from which a fine view of the general surface was attainable. as in the case of the görnerhorn glacier, the gradual perfecting of the structure was very manifest; the dirt, which first irregularly scattered over the surface, gradually assumed a striated appearance, and became more and more decided as the moraine was approached. descending from the alp, i endeavoured to measure some of the undulations; proceeding afterwards to the junction of the breithorn glacier with that of st. théodule. the end of the latter appears to be crumpled by its thrust against the former, and the moraine between them, instead of being raised, runs along a hollow which is flanked by the crumples on either side. the breithorn glacier became more and more attenuated, until finally it actually vanished under its own moraines. on the sides of the crevasses, by which the théodule glacier is here intersected, i thought i could plainly see two systems of veins cutting each other at an angle of fifteen or twenty degrees. reaching the görner glacier, at a place where its dislocation was very great, i proceeded down it past the riffelhorn, to a point where it seemed possible to scale the opposite mountain wall. here i crossed the glacier, treading with the utmost caution along the combs of ice, and winding through the entanglement of crevasses until the spur of the riffelhorn was reached; this i climbed to its summit, and afterwards crossed the green alp to our hotel. [sidenote: temptation. .] the foregoing good day's work was rewarded by a sound sleep at night. the tourists were called in succession next morning, but after each call i instantly subsided into deep slumber, and thus healthily spaced out the interval of darkness. day at length dawned and gradually brightened. i looked at my watch and found it twenty minutes to six. my guide had been lent to a party of gentlemen who had started at three o'clock for the summit of monte rosa, and he had left with me a porter who undertook to conduct me to one of the adjacent glaciers. but as i looked from my window the unspeakable beauty of the morning filled me with a longing to see the world from the top of monte rosa. i was in exceedingly good condition--could i not reach the summit alone? trained and indurated as i had been, i felt that the thing was possible; at all events i could try, without attempting anything which was not clearly within my power. footnotes: [a] now called, in the federal map, the "monte rosa glacier." görnerhorn is an old local name for the central mass of monte rosa.--l. c. t. [b] _see_ p. , footnote. second ascent of monte rosa, . ( .) [sidenote: a light scrip. .] whether my exercise be mental or bodily, i am always most vigorous when cool. during my student life in germany, the friends who visited me always complained of the low temperature of my room, and here among the alps it was no uncommon thing for me to wander over the glaciers from morning till evening in my shirt-sleeves. my object now was to go as light as possible, and hence i left my coat and neckcloth behind me, trusting to the sun and my own motion to make good the calorific waste. after breakfast i poured what remained of my tea into a small glass bottle, an ordinary demi-bouteille, in fact; the waiter then provided me with a ham sandwich, and, with my scrip thus frugally furnished, i thought the heights of monte rosa might be won. i had neither brandy nor wine, but i knew the immense amount of mechanical force represented by four ounces of bread and ham, and i therefore feared no failure from lack of nutriment. indeed, i am inclined to think that both guides and travellers often impair their vigour and render themselves cowardly and apathetic by the incessant "refreshing" which they deem it necessary to indulge in on such occasions. [sidenote: the guide expostulates. .] [sidenote: the guide halts. .] the guide whom lauener intended for me was at the door; i passed him and desired him to follow me. this he at first refused to do, as he did not recognise me in my shirt-sleeves; but his companions set him right, and he ran after me. i transferred my scrip to his shoulders, and led the way upward. once or twice he insinuated that that was not the way to the schwarze-see, and was probably perplexed by my inattention. from the summit of the ridge which bounds the görner glacier the whole grand panorama revealed itself, and on the higher slopes of monte rosa--so high, indeed, as to put all hope of overtaking them, or even coming near them, out of the question--a row of black dots revealed the company which had started at three o'clock from the hotel. they had made remarkably good use of their time, and i was afterwards informed that the cause of this was the intense cold, which compelled them to keep up the proper supply of heat by increased exertion. i descended swiftly to the glacier, and made for the base of monte rosa, my guide following at some distance behind me. one of the streams, produced by superficial melting, had cut for itself a deep wide channel in the ice; it was not too wide for a spring, and with the aid of a run i cleared it and went on. some minutes afterwards i could hear the voice of my companion exclaiming, in a tone of expostulation, "no, no, i won't follow you there." he however made a circuit, and crossed the stream; i waited for him at the place where the monte rosa glacier joins the rock, "_auf der platte_," and helped him down the ice-slope. at the summit of these rocks i again waited for him. he approached me with some excitement of manner, and said that it now appeared plain to him that i intended to ascend monte rosa, but that he would not go with me. i asked him to accompany me to the summit of the next cliff, which he agreed to do; and i found him of some service to me. he discovered the faint traces of the party in advance, and, from his greater experience, could keep them better in view than i could. we lost them, however, near the base of the cliff at which we aimed, and i went on, choosing as nearly as i could remember the route followed by lauener and myself a week previously, while my guide took another route, seeking for the traces. the glacier here is crevassed, and i was among the fissures some distance in advance of my companion. fear was manifestly getting the better of him, and he finally stood still, exclaiming, "no man can pass there." at the same moment i discovered the trace, and drew his attention to it; he approached me submissively, said that i was quite right, and declared his willingness to go on. we climbed the cliff, and discovered the trace in the snow above it. here i transferred the scrip and telescope to my own shoulders, and gave my companion a cheque for five francs. he returned, and i went on alone. the sun and heaven were glorious, but the cold was nevertheless intense, for it had frozen bitterly the night before. the mountain seemed more noble and lovely than when i had last ascended it; and as i climbed the slopes, crossed the shining cols, and rounded the vast snow-bosses of the mountain, the sense of being alone lent a new interest to the glorious scene. i followed the track of those who preceded me, which was that pursued by lauener and myself a week previously. once i deviated from it to obtain a glimpse of italy over the saddle which stretches from monte rosa to the lyskamm. deep below me was the valley, with its huge and dislocated _névé_, and the slope on which i hung was just sufficiently steep to keep the attention aroused without creating anxiety. i prefer such a slope to one on which the thought of danger cannot be entertained. i become more weary upon a dead level, or in walking up such a valley as that which stretches between visp and zermatt, than on a steep mountain side. the sense of weariness is often no index to the expenditure of muscular force: the muscles may be charged with force, and, if the nervous excitant be feeble, the strength lies dormant, and we are tired without exertion. but the thought of peril keeps the mind awake, and spurs the muscles into action; they move with alacrity and freedom, and the time passes swiftly and pleasantly. [sidenote: left alone. .] occupied with my own thoughts as i ascended, i sometimes unconsciously went too quickly, and felt the effects of the exertion. i then slackened my pace, allowing each limb an instant of repose as i drew it out of the snow, and found that in this way walking became rest. this is an illustration of the principle which runs throughout nature--to accomplish physical changes, _time_ is necessary. different positions of the limb require different molecular arrangements; and to pass from one to the other requires time. by lifting the leg slowly and allowing it to fall forward by its own gravity, a man may get on steadily for several hours, while a very slight addition to this pace may speedily exhaust him. of course the normal pace differs in different persons, but in all the power of endurance may be vastly augmented by the prudent outlay of muscular force. the sun had long shone down upon me with intense fervour, but i now noticed a strange modification of the light upon the slopes of snow. i looked upwards, and saw a most gorgeous exhibition of interference-colours. a light veil of clouds had drawn itself between me and the sun, and this was flooded with the most brilliant dyes. orange, red, green, blue--all the hues produced by diffraction were exhibited in the utmost splendour. there seemed a tendency to form circular zones of colour round the sun, but the clouds were not sufficiently uniform to permit of this, and they were consequently broken into spaces, each steeped with the colour due to the condition of the cloud at the place. three times during my ascent similar veils drew themselves across the sun, and at each passage the splendid phenomena were renewed. as i reached the middle of the mountain an avalanche was let loose from the sides of the lyskamm; the thunder drew my eyes to the place; i saw the ice move, but it was only the tail of the avalanche; still the volume of sound told me that it was a huge one. suddenly the front of it appeared from behind a projecting rock, hurling its ice-masses with fury into the valley, and tossing its rounded clouds of ice-dust high into the atmosphere. a wild long-drawn sound, multiplied by echoes, now descended from the heights above me. it struck me at first as a note of lamentation, and i thought that possibly one of the party which was now near the summit had gone over the precipice. on listening more attentively i found that the sound shaped itself into an english "hurrah!" i was evidently nearing the party, and on looking upwards i could see them, but still at an immense height above me. the summit still rose before them, and i therefore thought the cheer premature. a precipice of ice was now in front of me, around which i wound to the right, and in a few minutes found myself fairly at the bottom of the kamm. [sidenote: giddiness on the kamm. .] [sidenote: scrip left behind. .] i paused here for a moment, and reflected on the work before me. my head was clear, my muscles in perfect condition, and i felt just sufficient fear to render me careful. i faced the kamm, and went up slowly but surely, and soon heard the cheer which announced the arrival of the party at the summit of the mountain. it was a wild, weird, intermittent sound, swelling or falling as the echoes reinforced or enfeebled it. in getting through the rocks which protrude from the snow at the base of the last spur of the mountain, i once had occasion to stoop my head, and, on suddenly raising it, my eyes swam as they rested on the unbroken slope of snow at my left. the sensation was akin to giddiness, but i believe it was chiefly due to the absence of any object upon the snow upon which i could converge the axes of my eyes. up to this point i had eaten nothing. i now unloosed my scrip, and had two mouthfuls of sandwich and nearly the whole of the tea that remained. i found here that my load, light as it was, impeded me. when fine balancing is necessary, the presence of a very light load, to which one is unaccustomed, may introduce an element of danger, and for this reason i here left the residue of my tea and sandwich behind me. a long, long edge was now in front of me, sloping steeply upwards. as i commenced the ascent of this, the foremost of those whose cheer had reached me from the summit some time previously, appeared upon the top of the edge, and the whole party was seen immediately afterwards dangling on the kamm. we mutually approached each other. peter bohren, a well-known oberland guide, came first, and after him came the gentleman in his immediate charge. then came other guides with other gentlemen, and last of all my guide, lauener, with his strong right arm round the youngest of the party. we met where a rock protruded through the snow. the cold smote my naked throat bitterly, so to protect it i borrowed a handkerchief from lauener, bade my new acquaintances good bye, and proceeded upwards. i was soon at the place where the snow-ridge joins the rocks which constitute the crest of the mountain; through these my way lay, every step i took augmenting my distance from all life, and increasing my sense of solitude. i went up and down the cliffs as before, round ledges, through fissures, along edges of rock, over the last deep and rugged indentation, and up the rocks at its opposite side, to the summit. [sidenote: alone on the summit. .] [sidenote: the axe slips. .] a world of clouds and mountains lay beneath me. switzerland, with its pomp of summits, was clear and grand; italy was also grand, but more than half obscured. dark cumulus and dark crag vied in savagery, while at other places white snows and white clouds held equal rivalry. the scooped valleys of monte rosa itself were magnificent, all gleaming in the bright sunlight--tossed and torn at intervals, and sending from their rents and walls the magical blue of the ice. ponderous _névés_ lay upon the mountains, apparently motionless, but suggesting motion--sluggish, but indicating irresistible dynamic energy, which moved them slowly to their doom in the warmer valleys below. i thought of my position: it was the first time that a man had stood alone upon that wild peak, and were the imagination let loose amid the surrounding agencies, and permitted to dwell upon the perils which separated the climber from his kind, i dare say curious feelings might have been engendered. but i was prompt to quell all thoughts which might lessen my strength, or interfere with the calm application of it. once indeed an accident made me shudder. while taking the cork from a bottle which is deposited on the top, and which contains the names of those who have ascended the mountain, my axe slipped out of my hand, and slid some thirty feet away from me. the thought of losing it made my flesh creep, for without it descent would be utterly impossible. i regained it, and looked upon it with an affection which might be bestowed upon a living thing, for it was literally my staff of life under the circumstances. one look more over the cloud-capped mountains of italy, and i then turned my back upon them, and commenced the descent. the brown crags seemed to look at me with a kind of friendly recognition, and, with a surer and firmer feeling than i possessed on ascending, i swung myself from crag to crag and from ledge to ledge with a velocity which surprised myself. i reached the summit of the kamm, and saw the party which i had passed an hour and a half before, emerging from one of the hollows of the mountain; they had escaped from the edge which now lay between them and me. the thought of the possible loss of my axe at the summit was here forcibly revived, for without it i dared not take a single step. my first care was to anchor it firmly in the snow, so as to enable it to bear at times nearly the whole weight of my body. in some places, however, the anchor had but a loose hold; the "cornice" to which i have already referred became granular, and the handle of the axe went through it up to the head, still, however, remaining loose. some amount of trust had thus to be withdrawn from the staff and placed in the limbs. a curious mixture of carelessness and anxiety sometimes fills the mind on such occasions. i often caught myself humming a verse of a frivolous song, but this was mechanical, and the substratum of a man's feelings under such circumstances is real earnestness. the precipice to my left was a continual preacher of caution, and the slope to my right was hardly less impressive. i looked down the former but rarely, and sometimes descended for a considerable time without looking beyond my own footsteps. the power of a thought was illustrated on one of these occasions. i had descended with extreme slowness and caution for some time, when looking over the edge of the cornice i saw a row of pointed rocks at some distance below me. these i felt must receive me if i slipped over, and i thought how before reaching them i might so break my fall as to arrive at them unkilled. this thought enabled me to double my speed, and as long as the spiky barrier ran parallel to my track i held my staff in one hand, and contented myself with a slight pressure upon it. i came at length to a place where the edge was solid ice, which rose to the level of the cornice, the latter appearing as if merely stuck against it. a groove ran between the ice and snow, and along this groove i marched until the cornice became unsafe, and i had to betake myself to the ice. the place was really perilous, but, encouraging myself by the reflection that it would not last long, i carefully and deliberately hewed steps, causing them to dip a little inward, so as to afford a purchase for the heel of my boot, never forsaking one till the next was ready, and never wielding my hatchet until my balance was secured. i was soon at the bottom of the kamm, fairly out of danger, and full of glad vigour i bore swiftly down upon the party in advance of me. it was an easy task to me to fuse myself amongst them as if i had been an old acquaintance, and we joyfully slid, galloped, and rolled together down the residue of the mountain. [sidenote: accident on the kamm. .] the only exception was the young gentleman in lauener's care. a day or two previously he had, i believe, injured himself in crossing the gemmi, and long before he reached the summit of monte rosa his knee swelled, and he walked with great difficulty. but he persisted in ascending, and lauener, seeing his great courage, thought it a pity to leave him behind. i have stated that a portion of the kamm was solid ice. on descending this, mr. f.'s footing gave way, and he slipped forward. lauener was forced to accompany him, for the place was too steep and slippery to permit of their motion being checked. both were on the point of going over the lyskamm side of the mountain, where they would have indubitably been dashed to pieces. "there was no escape there," said lauener, in describing the incident to me subsequently, "but i saw a possible rescue at the other side, so i sprang to the right, forcibly swinging my companion round; but in doing so, the bâton tripped me up; we both fell, and rolled rapidly over each other down the incline. i knew that some precipices were in advance of us, over which we should have gone, so, releasing myself from my companion, i threw myself in front of him, stopped myself with my axe, and thus placed a barrier before him." after some vain efforts at sliding down the slopes on a bâton, in which practice i was fairly beaten by some of my new friends, i attached myself to the invalid, and walked with him and lauener homewards. had i gone forward with the foremost of the party, i should have completed the expedition to the summit and back in a little better than nine hours. [sidenote: danger of climbing alone. .] i think it right to say one earnest word in connexion with this ascent; and the more so as i believe a notion is growing prevalent that half what is said and written about the dangers of the alps is mere humbug. no doubt exaggeration is not rare, but i would emphatically warn my readers against acting upon the supposition that it is general. the dangers of mont blanc, monte rosa, and other mountains, are real, and, if not properly provided against, may be terrible. i have been much accustomed to be alone upon the glaciers, but sometimes, even when a guide was in front of me, i have felt an extreme longing to have a second one behind me. less than two good ones i think an arduous climber ought not to have; and if climbing without guides were to become habitual, deplorable consequences would assuredly sooner or later ensue. ( .) the th of august i spent upon the furgge glacier at the base of mont cervin, and what it taught me shall be stated in another place. the evening of this day was signalised by the pleasant acquaintances which it gave me. it was my intention to cross the weissthor on the morning of the th, but thunder, lightning, and heavy rain opposed the project, and with two friends i descended, amid pitiless rain, to zermatt. next day i walked by way of stalden to saas, where i made the acquaintance of herr imseng, the curé, and on the st ascended to the distel alp. near to this place the allalein glacier pushes its huge terminus right across the valley and dams up the streams descending from the mountains higher up, thus giving birth to a dismal lake. at one end of this stands the mattmark hotel, which was to be my headquarters for a few days. [sidenote: ascent of a boulder. .] i reached the place in good company. near to the hotel are two magnificent boulders of green serpentine, which have been lodged there by one of the lateral glaciers; and two of the ladies desiring to ascend one of these rocks, a friend and myself helped them to the top. the thing was accomplished in a very spirited way. indeed the general contrast, in regard to energy, between the maidens of the british isles and those of the continent and of america is extraordinary. surely those who talk of this country being in its old age overlook the physical vigour of its sons and daughters. they are strong, but from a combination of the greatest forces we may obtain a small resultant, because the forces may act in opposite directions and partly neutralize each other. herein, in fact, lies britain's weakness; it is strength ill-directed; and is indicative rather of the perversity of young blood than of the precision of mature years. [sidenote: dismal quarters. .] immediately after this achievement i was forsaken by my friends, and remained the only visitor in the hotel. a dense gray cloud gradually filled the entire atmosphere, from which the rain at length began to gush in torrents. the scene from the windows of the hotel was of the most dismal character; the rain also came through the roof, and dripped from the ceiling to the floor. i endeavoured to make a fire, but the air would not let the smoke of the pine-logs ascend, and the biting of the hydrocarbons was excruciating to the eyes. on the whole, the cold was preferable to the smoke. during the night the rain changed to snow, and on the morning of the nd all the mountains were thickly covered. the gray delta through which a river of many arms ran into the mattmark see was hidden; against some of the windows of the _salle à manger_ the snow was also piled, obscuring more than half their light. i had sent my guide to visp, and two women and myself were the only occupants of the place. it was extremely desolate--i felt, moreover, the chill of monte rosa in my throat, and the conditions were not favourable to the cure of a cold. on the rd the allalein glacier was unfit for work; i therefore ascended to the summit of the monte moro, and found the valaisian side of the pass in clear sunshine, while impenetrable fog met us on the italian side. i examined the colour of the freshly fallen snow; it was not an ordinary blue, and was even more transparent than the blue of the firmament. when the snow was broken the light flashed forth; when the staff was dug into the snow and withdrawn, the blue gleam appeared; when the staff lay in a hole, although there might be a sufficient space all round it, the coloured light refused to show itself. my cough kept me awake on the night of the rd, and my cold was worse next day. i went upon the allalein glacier, but found myself by no means so sure a climber as usual. the best guides find that their powers vary; they are not equally competent on all days. i have heard a celebrated chamouni guide assert that a man's _morale_ is different on different days. the morale in my case had a physical basis, and it probably has so in all. the allalein glacier, as i have said, crosses the valley and abuts against the opposite mountain; here it is forced to turn aside, and in consequence of the thrust and bending it is crumpled and crevassed. the wall of the mattmark see is a fine glacier section: looked at from a distance, the ridges and fissures appear arranged like a fan. the structure of the crumpled ice varies from the vertical to the horizontal, and the ridges are sometimes split _along_ the planes of structure. the aspect of this portion of the glacier from some of the adjacent heights is exceedingly interesting. [sidenote: the vault of the allalein. .] on the morning of the th i had two hours' clambering over the mountains before breakfast, and traced the action of ancient glaciers to a great height. the valley of saas in this respect rivals that of hasli; the flutings and polishings being on the grandest scale. after breakfast i went to the end of the allalein glacier, where the saas visp river rushes from it: the vault was exceedingly fine, being composed of concentric arches of clear blue ice. i spent several hours here examining the intimate structure of the ice, and found the vacuum disks which i shall describe at another place, of the greatest service to me. as at rosenlaui and elsewhere, they here taught me that the glacier was composed of an aggregate of small fragments, each of which had a definite plane of crystallization. where the ice was partially weathered the surfaces of division between the fragments could be traced through the coherent mass, but on crossing these surfaces the direction of the vacuum disks changed, indicating a similar change of the planes of crystallization. the blue veins of the glacier went through its component fragments irrespective of these planes. sometimes the vacuum disks were parallel to the veins, sometimes across them, sometimes oblique to them. several fine masses of ice had fallen from the arch upon its floor, and these were disintegrated to the core. a kick, or a stroke of an axe, sufficed to shake masses almost a cubic yard in size into fragments varying not much on either side of a cubic inch. the veining was finely preserved on the concentric arches of the vault, and some of them apparently exhibited its abolition, or at least confusion, and fresh development by new conditions of pressure. the river being deep and turbulent this day, to reach its opposite side i had to climb the glacier and cross over the crown of its highest arch; this enabled me to get quite in front of the vault, to enter it, and closely inspect those portions where the structure appeared to change. i afterwards ascended the steep moraine which lies between the allalein and the smaller glacier to the left of it; passing to the latter at intervals to examine its structure. i was at length stopped by the dislocated ice; and from the heights i could count a system of seven dirt-bands, formed by the undulations on the surface of the glacier. on my return to the hotel i found there a number of well-known alpine men who intended to cross the adler pass on the following day. herr imseng was there: he came to me full of enthusiasm, and asked me whether i would join him in an ascent of the dom: we might immediately attack it; and he felt sure that we should succeed. the dom is the highest of the mischabel peaks, and is one of the grandest of the alps. i agreed to join the curé, and with this understanding we parted for the night. [sidenote: avalanche at saas. .] thursday, th august.--a wild stormy morning after a wild and rainy night: the adler pass being impassable, the mountaineers returned, and imseng informed me that the dom must be abandoned. he gave me the statistics of an avalanche which had fallen in the valley some years before. within the memory of man saas had never been touched by an avalanche, but a tradition existed that such a catastrophe had once occurred. on the th of march, , at eight o'clock in the morning, the curé was in his room; when he heard the cracking of pine-branches, and inferred from the sound that an avalanche was descending upon the village. it dashed in the windows of his house and filled his rooms with snow; the sound it produced being sufficient to mask the crashing of the timbers of an adjacent house. three persons were killed. on the rd of april, , heavy snow fell at saas; the curé waited until it had attained a depth of four feet, and then retreated to fée. that night an avalanche descended, and in the line of its rush was a house in which five or six and twenty people had collected for safety: nineteen of them were killed. the curé afterwards showed me the site of the house, and the direction of the avalanche. it passed through a pine wood; and on expressing my surprise that the trees did not arrest it, he replied that the snow was "quite like dust," and rushed among the trees like so much water. to return from fée to saas on the day following he found it necessary to carry two planks. kneeling upon one of them, he pushed the other forward, and transferred his weight to it, drawing the other after him and repeating the same act. the snow was like flour, and would not otherwise bear his weight. seeing no prospect of fine weather, i descended to saas on the afternoon of the th. i was the only guest at the hotel; but during the evening i was gratified by the unexpected arrival of my friend hirst, who was on his way over the monte moro to italy. [sidenote: the fÉe glacier. .] [sidenote: snow, vapour and cloud. .] for the last five days it had been a struggle between the north wind and the south, each edging the other by turns out of its atmospheric bed, and producing copious precipitation; but now the conflict was decided--the north had prevailed, and an almost unclouded heaven overspread the alps. the few white fleecy masses that remained were good indications of the swift march of the wind in the upper air. my friend and i resolved to have at least one day's excursion together, and we chose for it the glacier of the fée. ascending the mountain by a well-beaten path, we passed a number of "calvaries" filled with tattered saints and virgins, and soon came upon the rim of a flattened bowl quite clasped by the mountains. in its centre was the little hamlet of fée, round which were fresh green pastures, and beyond it the perpetual ice and snow. it was exceedingly picturesque--a scene of human beauty and industry where savagery alone was to be expected. the basin had been scooped by glaciers, and as we paused at its entrance the rounded and fluted rocks were beneath our feet. the alphubel and the mischabel raised their crowns to heaven in front of us; the newly fallen snow clung where it could to the precipitous crags of the mischabel, but on the summits it was the sport of the wind. sometimes it was borne straight upwards in long vertical striæ; sometimes the fibrous columns swayed to the right, sometimes to the left; sometimes the motion on one of the summits would quite subside; anon the white peak would appear suddenly to shake itself to dust, which it yielded freely to the wind. i could see the wafted snow gradually melt away, and again curdle up into true white cloud by precipitation; this in its turn would be pulled asunder like carded wool, and reduced a second time to transparent vapour. in the middle of the ice of the fée stands a green alp, not unlike the jardin; up this we climbed, halting at intervals upon its grassy knolls to inspect the glacier. i aimed at those places where on à priori grounds i should have thought the production of the veined structure most likely, and reached at length the base of a wall of rock from the edge of which long spears of ice depended. here my friend halted, while lauener and myself climbed the precipice, and ascended to the summit of the alp. the snow was deep at many places, and our immersions in unseen holes very frequent. from the peak of the fée alp a most glorious view is obtained; in point of grandeur it will bear comparison with any in the alps, and its seclusion gives it an inexpressible charm. we remained for half an hour upon the warm rock, and then descended. it was our habit to jump from the higher ledges into the deep snow below them, in which we wallowed as if it were flour; but on one of these occasions i lighted on a stone, and the shock produced a curious effect upon my hearing. i appeared suddenly to lose the power of appreciating deep sounds, while the shriller ones were comparatively unimpaired. after i rejoined my friend it required attention on my part to hear him when he spoke to me. this continued until i approached the end of the glacier, when suddenly the babblement of streams, and a world of sounds to which i had been before quite deaf burst in upon me. the deafness was probably due to a strain of the tympanum, such as we can produce artificially, and thus quench low sounds, while shrill ones are scarcely affected. [sidenote: "a terrible hole." .] i was anxious to quit saas early next morning, but the curé expressed so strong a wish to show us what he called a _schauderhaftes loch_--a terrible hole--which he had himself discovered, that i consented to accompany him. we were joined by his assistant and the priest of fée. the stream from the fée glacier has cut a deep channel through the rocks, and along the right-hand bank of the stream we ascended. it was very rough with fallen crags and fallen pines amid which we once or twice lost our way. at length we came to an aperture just sufficient to let a man's body through, and were informed by our conductor that our route lay along the little tunnel: he lay down upon his stomach and squeezed himself through it like a marmot. i followed him; a second tunnel, in which, however, we could stand upright, led into a spacious cavern, formed by the falling together of immense slabs of rock which abutted against each other so as to form a roof. it was the very type of a robber den; and when i remarked this, it was at once proposed to sing a verse from schiller's play. the young priest had a powerful voice--he led and we all chimed in. [sidenote: song of the robbers. .] "ein frohes leben führen wir, ein leben voller wonne. der wald ist unser nachtquartier, bei sturm und wind hanthieren wir, der mond ist unsre sonne." herr imseng wore his black coat; the others had taken theirs off, but they wore their clerical hats, black breeches and stockings. we formed a singular group in a singular place, and the echoed voices mingled strangely with the gusts of the wind and the rush of the river. soon afterwards i parted from my friend, and descended the valley to visp, where i also parted with my guide. he had been with me from the nd of july to the th of august, and did his duty entirely to my satisfaction. he is an excellent iceman, and is well acquainted both with the glaciers of the oberland and of the valais. he is strong and good-humoured, and were i to make another expedition of the kind i don't think that i should take any guide in the oberland in preference to christian lauener. ( .) [sidenote: climbers and science. .] it is a singular fact that as yet we know absolutely nothing of the winter temperature of any one of the high alpine summits. no doubt it is a sufficient justification of our alpine men, as regards their climbing, _that they like it_. this plain reason is enough; and no man who ever ascended that "bad eminence" primrose hill, or climbed to hampstead heath for the sake of a freer horizon, can consistently ask a better. as regards physical science, however, the contributions of our mountaineers have as yet been _nil_, and hence, when we hear of the scientific value of their doings, it is simply amusing to the climbers themselves. i do not fear that i shall offend them in the least by my frankness in stating this. their pleasure is that of overcoming acknowledged difficulties, and of witnessing natural grandeur. but i would venture to urge that our alpine men will not find their pleasure lessened by embracing a scientific object in their doings. they have the strength, the intelligence, and let them add to these the accuracy which physical science now demands, and they may contribute work of enduring value. mr. casella will gladly teach them the use of his minimum-thermometers; and i trust that the next seven years will not pass without making us acquainted with the winter temperature of every mountain of note in switzerland.[a] i had thought of this subject since i first read the conjectures of de saussure on the temperature of mont blanc; but in i met auguste balmat at the jardin, and there learned from him that he entertained the idea of placing a self-registering thermometer at the summit of the mountain. balmat was personally a stranger to me at the time, but professor forbes's writings had inspired me with a respect for him, which this unprompted idea of his augmented. he had procured a thermometer, the graduation of which, however, he feared was not low enough. as an encouragement to balmat, and with the view of making his laudable intentions known, i communicated them to the royal society, and obtained from the council a small grant of money to purchase thermometers and to assist in the expenses of an ascent. i had now the thermometers in my possession; and having completed my work at zermatt and saas, my next desire was to reach chamouni and place the instruments on the top of mont blanc. i accordingly descended the valley of the rhone to martigny, crossed the tête noire, and arrived at chamouni on the th of august, . [sidenote: difficulties at chamouni. .] balmat was engaged at this time as the guide of mr. alfred wills, who, however, kindly offered to place him at my disposal; and also expressed a desire to accompany me himself and assist me in my observations. i gladly accepted a proposal which gave me for companion so determined a climber and so estimable a man. but chamouni was rife with difficulties. in the guide chef had the good sense to give me considerable liberty of action. now his mood was entirely changed: he had been "molested" for giving me so much freedom. i wished to have a boy to carry a small instrument for me up the mer de glace--he would not allow it; i must take a guide. if i ascended mont blanc he declared that i must take four guides; that, in short, i must in all respects conform to the rules made for ordinary tourists. i endeavoured to explain to him the advantages which chamouni had derived from the labours of men of science; it was such men who had discovered it when it was unknown, and it was by their writings that the attention of the general public had been called towards it. it was a bad recompense, i urged, to treat a man of science as he was treating me. this was urged in vain; he shrugged his shoulders, was very sorry, but the thing could not be changed. i then requested to know his superior, that i might apply to him; he informed me that there were a president and commission of guides at chamouni, who were the proper persons to decide the question, and he proposed to call them together on the st of august, at seven p.m., on condition that i was to be present to state my own case. to this i agreed. i spent that day quite alone upon the mer de glace, and climbed amid a heavy snow-storm to the cleft station over trélaporte. when i reached the montanvert i was wet and weary, and would have spent the night there were it not for my engagement with the guide chef. i descended amid the rain, and at the appointed hour went to his bureau. he met me with a polite sympathetic shrug; explained to me that he had spoken to the commission, but that it could not assemble _pour une chose comma ça_; that the rules were fixed, and i must abide by them. "well," i responded, "you think you have done your duty; it is now my turn to perform mine. if no other means are available i will have this transaction communicated to the sardinian government, and i don't think that it will ratify what you have done." the guide chef evidently did not believe a word of it. previous to taking any further step i thought it right to see the president of the commission of guides, who was also syndic of the commune. i called upon him on the morning of the st of september, and, assuming that he knew all about the transaction, spoke to him accordingly. he listened to me for a time, but did not seem to understand me, which i ascribed partly to my defective french pronunciation. i expressed a hope that he did comprehend me; he said he understood my words very well, but did not know their purport. in fact he had not heard a single word about me or my request. he stated with some indignation that, so far from its being a subject on which the commission could not assemble, it was one which it was their especial duty to take into consideration. our conference ended with the arrangement that i was to write him an official letter stating the case, which he was to forward to the intendant of the province of faucigny resident at bonneville. all this was done. [sidenote: the intendant memorialised. .] i subsequently memorialised the intendant himself; and balmat visited him to secure his permission to accompany me. i have to record, that from first to last the intendant gave me his sympathy and support. he could not alter laws, but he deprecated a "judaical" interpretation of them. his final letter to myself was as follows:-- [sidenote: the intendant's response. .] "intendance royale de la province de faucigny, "bonneville, septembre, . "monsieur,-- "j'apprends avec une véritable peine les difficultés que vous rencontrez de la part de m. le guide chef pour l'effectuation de votre périlleuse entreprise scientifique, mais je dois vous dire aussi avec regret que ces difficultés résident dans un règlement fait en vue de la sécurité des voyageurs, quel que puisse être le but de leurs excursions. "désireux néanmoins de vous être utile, notamment en la circonstance, j'invite aujourd'hui même m. le guide chef à avoir égard à votre projet, à faire en sa faveur une exception au règlement ci-devant eu, tant qu'il n'y aura aucun danger pour votre sûreté et celle des personnes qui vous accompagneront, et enfin de se prêter dans les limites de ses moyens et attributions pour l'heureux succès de l'expédition, dont les conséquences et résultats n'intéressent pas seulement la science, mais encore la vallée de chamounix en particulier. "agréez, monsieur, "l'assurance de ma consideration très-distinguée. "pour l'intendant en congé, "le secrétaire, "delÉglise." while waiting for this permission i employed myself in various ways. on the nd of september i ascended the brévent, from which mont blanc is seen to great advantage. from chamouni its vast slopes are so foreshortened that one gets a very imperfect idea of the extent to be traversed to reach the summit. what, however, struck me most on the brévent was the changed relation of the aiguille du dru and the aiguille verte. from montanvert the former appears a most imposing mass, while the peak of the latter appears rather dwarfed behind it; but from the brévent the aiguille du dru is a mere pinnacle stuck in the breast of the grander pyramid of the aiguille verte. [sidenote: the "sÉracs" revisited. .] on the th i rose early, and, strapping on my telescope, ascended to the montanvert, where i engaged a youth to accompany me up the glacier. the heavens were clear and beautiful:--blue over the aiguille du dru, blue over the jorasse and mont mallet, deep blue over the pinnacles of charmoz, and the same splendid tint stretched grandly over the col du géant and its aiguille. no trace of condensation appeared till towards eleven o'clock, when a little black balloon of cloud swung itself over the aiguilles rouges. at one o'clock there were two large masses and a little one between them; while higher up a white veil, almost too thin to be visible, spread over a part of the heavens. at the zenith, however, and south, north, and west, the blue seemed to deepen as the day advanced. i visited the ice-wall at the tacul, which seemed lower than it was last year; the cascade of le géant appeared also far less imposing. only in the early part of summer do we see the ice in its true grandeur: its edges and surfaces are then sharp and clear, but afterwards its nobler masses shrink under the influence of sun and air. the _séracs_ now appeared wasted and dirty, and not the sharp angular ice-castles which rose so grandly when i first saw them. thirteen men had crossed the col du géant on the day previous, and left an ample trace behind them. this i followed nearly to the summit of the fall. the condition of the glacier was totally different from that of the opposite side on the previous year. the ice was riven, burrowed, and honeycombed, but the track amid all was easy: a vigorous english maiden might have ascended the fall without much difficulty. my object now was to examine the structure of the fall; but the ice was not in a good condition for such an examination: it was too much broken. still a definite structure was in many places to be traced, and some of them apparently showed structure and bedding at a high angle to each other, but i could not be certain of it. i paused at every commanding point of view and examined the ice through my opera-glass; but the result was inconclusive. i observed that the terraces which compose the fall do not front the middle of the glacier, but turn their foreheads rather towards its eastern side, and the consequence is that the protuberances lower down, which are the remains of these terraces, are highest at the same side. standing at the base of the aiguille noire, and looking downwards where the glacier des périades pushes itself against the géant, a series of fine crumples is formed on the former, cut across by crevasses, on the walls of which a forward and backward dipping of the blue veins is exhibited. huge crumples are also formed by the glacier du géant, which are well seen from a point nearly opposite the lowest lateral moraine of the glacier des périades. in some cases the upper portions of the crumples had scaled off so as to form arches of ice--a consequence doubtless of the pressure. [sidenote: thermometer at the jardin. .] the beauty of some alpine skies is treacherous; in fact the deepest blue often indicates an atmosphere charged almost to saturation with aqueous vapour. this was the case on the present occasion. soon after reaching chamouni in the evening, rain commenced and continued with scarcely any intermission until the afternoon of the th. i had given up all hopes of being able to ascend mont blanc; and hence resolved to place the thermometers in some more accessible position. on the th accordingly, accompanied by mr. wills, balmat, and some other friends, i ascended to the summit of the jardin, where we placed two thermometers: one in the ice, at a depth of three feet below the surface; another on a ledge of the highest rock.[b] the boiling point of water at this place was . ° fahr. deep snow was upon the talèfre, and the surrounding precipices were also heavily laden. avalanches thundered incessantly from the aiguille verte and the other mountains. scarcely five minutes on an average intervened between every two successive peals; and after the direct shock of each avalanche had died away the air of the basin continued to be shaken by the echoes reflected from its bounding walls. [sidenote: evening red. .] the day was far spent before we had completed our work. all through the weather had been fine, and towards evening augmented to magnificence. as we descended the glacier from the couvercle the sun was just disappearing, and the western heaven glowed with crimson, which crept gradually up the sky until finally it reached the zenith itself. such intensity of colouring is exceedingly rare in the alps; and this fact, together with the known variations in the intensity of the firmamental blue, justify the conclusion that the colouring must, in a great measure, be due to some _variable constituent_ of the atmosphere. if _the air_ were competent to produce these magnificent effects they would be the rule instead of the exception. [sidenote: finished work. .] no sooner had the thermometers been thus disposed of than the weather appeared to undergo a permanent change. on the th it was perfectly fine--not the slightest mist upon mont blanc; on the th this was also the case. balmat still had the old thermometer to which i have already referred; it might not do to show the minimum temperature of the air, but it might show the temperature at a certain depth below the surface. i find in my own case that the finishing of work has a great moral value: work completed is a safe fulcrum for the performance of other work; and even though in the course of our labours experience should show us a better means of accomplishing a given end, it is often far preferable to reach the end, even by defective means, than to swerve from our course. the habits which this conviction had superinduced no doubt influenced me when i decided on placing balmat's thermometer on the summit of mont blanc. footnotes: [a] i find with pleasure that my friend mr. john ball is now exerting himself in this direction. [b] the minimum temperature of the subsequent winter, as shown by this thermometer, was - ° fahr., or ° below the freezing point. the instrument placed in the ice was broken. second ascent of mont blanc, . ( .) [sidenote: shadows of the aiguilles. .] on the th of september, at - / a.m. the sunbeams had already fallen upon the mountain; but though the sky above him, and over the entire range of the aiguilles, was without a cloud, the atmosphere presented an appearance of turbidity resembling that produced by the dust and thin smoke mechanically suspended in a london atmosphere on a dry summer's day. at minutes past we quitted chamouni, bearing with us the good wishes of a portion of its inhabitants. [sidenote: interference-spectra. .] a lady accompanied us on horseback to the point where the path to the grands mulets deviates from that to the plan des aiguilles; here she turned to the left, and we proceeded slowly upwards, through woods of pine, hung with fantastic lichens: escaping from the gloom of these, we emerged upon slopes of bosky underwood, green hazel, and green larch, with the red berries of the mountain-ash shining brightly between them. through the air above us, like gnomons of a vast sundial, the aiguilles cast their fanlike shadows, which moved round as the day advanced. slopes of rhododendrons with withered flowers next succeeded, but the colouring of the bilberry-leaves was scarcely less exquisite than the freshest bloom of the alpine rose. for a long time we were in the cool shadow of the mountain, catching, at intervals, through the twigs in front of us, glimpses of the sun surrounded by coloured spectra. on one occasion a brow rose in front of me; behind it was a lustrous space of heaven, adjacent to the sun, which, however, was hidden behind the brow; against this space the twigs and weeds upon the summit of the brow shone as if they were self-luminous, while some bits of thistle-down floating in the air appeared, where they crossed this portion of the heavens, like fragments of the sun himself. once the orb appeared behind a rounded mass of snow which lay near the summit of the aiguille du midi. looked at with the naked eyes, it seemed to possess a billowy motion, the light darting from it in dazzling curves,--a subjective effect produced by the abnormal action of the intense light upon the eye. as the sun's disk came more into view, its rays however still grazing the summit of the mountain, interference-spectra darted from it on all sides, and surrounded it with a glory of richly-coloured bars. mingling however with the grandeur of nature, we had the anger and obstinacy of man. with a view to subsequent legal proceedings, the guide chef sent a spy after us, who, having satisfied himself of our delinquency, took his unpleasant presence from the splendid scene. strange to say, though the luminous appearance of bodies projected against the sky adjacent to the rising sun is a most striking and beautiful phenomenon, it is hardly ever seen by either guides or travellers; probably because they avoid looking towards a sky the brightness of which is painful to the eyes. in auguste balmat had never seen the effect; and the only written description of it which we possess is one furnished by professor necker, in a letter to sir david brewster, which is so interesting that i do not hesitate to reproduce it here:-- [sidenote: professor necker's letter. .] "i now come to the point," writes m. necker, "which you particularly wished me to describe to you; i mean the luminous appearance of trees, shrubs, and birds, when seen from the foot of a mountain a little before sunrise. the wish i had to see again the phenomenon before attempting to describe it made me detain this letter a few days, till i had a fine day to go to see it at the mont salève; so yesterday i went there, and studied the fact, and in elucidation of it i made a little drawing, of which i give you here a copy: it will, with the explanation and the annexed diagram (fig. ), impart to you, i hope, a correct idea of the phenomenon. you must conceive the observer placed at the foot of a hill interposed between him and the place where the sun is rising, and thus entirely in the shade; the upper margin of the mountain is covered with woods or detached trees and shrubs, which are projected as dark objects on a very bright and clear sky, except at the very place where the sun is just going to rise, for there all the trees and shrubs bordering the margin are entirely,--branches, leaves, stem and all,--of a pure and brilliant white, appearing extremely bright and luminous, although projected on a most brilliant and luminous sky, as that part of it which surrounds the sun always is. all the minutest details, leaves, twigs, &c., are most delicately preserved, and you would fancy you saw these trees and forests made of the purest silver, with all the skill of the most expert workman. the swallows and other birds flying in those particular spots appear like sparks of the most brilliant white. unfortunately, all these details, which add so much to the beauty of this splendid phenomenon, cannot be represented in such small sketches. [illustration: fig. . luminous trees projected against the sky at sunrise.] "neither the hour of the day nor the angle which the object makes with the observer appears to have any effect; for on some occasions i have seen the phenomenon take place at a very early hour in the morning. yesterday it was a.m., when i saw it as represented in fig. . i saw it again on the same day at p.m., at a different place of the same mountain, for which the sun was just setting. at one time the angle of elevation of the lighted white shrubs above the horizon of the spectator was about °, while at another place it was only °. but the extent of the field of illumination is variable, according to the distance at which the spectator is placed from it. when the object behind which the sun is just going to rise, or has just been setting, is very near, no such effect takes place. in the case represented in fig. the distance was about mètres, or english feet, from the spectator in a direct line, the height above his level being mètres, or english feet, and the horizontal line drawn from him to the horizontal projection of these points on the plane of his horizon being mètres, or english feet, as will be seen in the following diagram, fig. . [sidenote: silver trees at sunrise. .] [illustration: fig. . luminous trees projected against the sky at sunrise.] [sidenote: birds as sparks or stars. .] "in this case only small shrubs and the lower half of the stem of a tree are illuminated white, and the horizontal extent of this effect is also comparatively small; while at other places when i was near the edge behind which the sun was going to rise no such effect took place. but on the contrary, when i have witnessed the phenomenon at a greater distance and at a greater height, as i have seen it other times on the same and on other mountains of the alps, large tracts of forests and immense spruce-firs were illuminated white throughout their whole length, as i have attempted to represent in fig. , and the corresponding diagram, fig. . nothing can be finer than these silver-looking spruce-forests. at the same time, though at a distance of more than a thousand mètres, a vast number of large swallows or swifts (_cypselus alpinus_), which inhabit these high rocks, were seen as small brilliant stars or sparks moving rapidly in the air. from these facts it appears to me obvious that the extent of the illuminated spots varies in a direct ratio of their distance; but at the same time that there must be a constant angular space, corresponding probably to the zone, a few minutes of a degree wide, around the sun's disk, which is a limit to the occurrence of the appearance. this would explain how the real extent which it occupies on the earth's surface varies with the relative distance of the spot from the eye of the observer, and accounts also for the phenomenon being never seen in the low country, where i have often looked for it in vain. now that you are acquainted with the circumstances of the fact, i have no doubt you will easily observe it in some part or other of your scotch hills; it may be some long heather or furze will play the part of our alpine forests, and i would advise you to try and place a bee-hive in the required position, and it would perfectly represent our swallows, sparks, and stars." [illustration: fig. . luminous trees projected against the sky at sunrise.] [illustration: fig. . luminous trees projected against the sky at sunrise.] [sidenote: the ladder condemned. .] our porters, with one exception, reached the pierre à l'echelle as soon as ourselves; and here having refreshed themselves, and the due exchange of loads having been made, we advanced upon the glacier, which we crossed, until we came nearly opposite to the base of the grands mulets. the existence of one wide crevasse, which was deemed impassable, had this year introduced the practice of assailing the rocks at their base, and climbing them to the cabin, an operation which balmat wished to avoid. at chamouni, therefore, he had made inquiries regarding the width of the chasm, and acting on his advice i had had a ladder constructed in two pieces, which, united together by iron attachments, was supposed to be of sufficient length to span the fissure. on reaching the latter, the pieces were united, and the ladder thrown across, but the bridge was so frail and shaky at the place of junction, and the chasm so deep, that balmat pronounced the passage impracticable. [sidenote: crossing crevasses. .] the porters were all grouped beside the crevasse when this announcement was made, and, like hounds in search of the scent, the group instantly broke up, seeking in all directions for a means of passage. the talk was incessant and animating; attention was now called in one direction, anon in another, the men meanwhile throwing themselves into the most picturesque groups and attitudes. all eyes at length were directed upon a fissure which was spanned at one point by an arch of snow, certainly under two feet deep at the crown. a stout rope was tied round the waist of one of our porters, and he was sent forward to test the bridge. he approached it cautiously, treading down the snow to give it compactness, and thus make his footing sure as he advanced; bringing regelation into play, he gave the mass the necessary continuity, and crossed in safety. the rope was subsequently stretched over the _pont_, and each of us causing his right hand to slide along it, followed without accident. soon afterwards, however, we met with a second and very formidable crevasse, to cross which we had but half of our ladder, which was applied as follows:--the side of the fissure on which we stood was lower than the opposite one; over the edge of the latter projected a cornice of snow, and a ledge of the same material jutted from the wall of the crevasse, a little below us. the ladder was placed from ledge to cornice, both of its ends being supported by snow. i could hardly believe that so frail a bearing could possibly support a man's weight; but a porter was tied as before, and sent up the ladder, while we followed protected by the rope. we were afterwards tied together, and thus advanced in an orderly line to the grands mulets. [sidenote: gorgeous sunset. .] the cabin was wet and disagreeable, but the sunbeams fell upon the brown rocks outside, and thither mr. wills and myself repaired to watch the changes of the atmosphere. i took possession of the flat summit of a prism of rock, where, lying upon my back, i watched the clouds forming, and melting, and massing themselves together, and tearing themselves like wool asunder in the air above. it was nature's language addressed to the intellect; these clouds were visible symbols which enabled us to understand what was going on in the invisible air. here unseen currents met, possessing different temperatures, mixing their contents both of humidity and motion, producing a mean temperature unable to hold their moisture in a state of vapour. the water-particles, obeying their mutual attractions, closed up, and a visible cloud suddenly shook itself out, where a moment before we had the pure blue of heaven. some of the clouds were wafted by the air towards atmospheric regions already saturated with moisture, and along their frontal borders new cloudlets ever piled themselves, while the hinder portions, invaded by a drier or a warmer air, were dissipated; thus the cloud advanced, with gain in front and loss behind, its permanence depending on the balance between them. the day waned, and the sunbeams began to assume the colouring due to their passage through the horizontal air. the glorious light, ever deepening in colour, was poured bounteously over crags, and snows, and clouds, and suffused with gold and crimson the atmosphere itself. i had never seen anything grander than the sunset on that day. clouds with their central portions densely black, denying all passage to the beams which smote them, floated westward, while the fiery fringes which bordered them were rendered doubly vivid by contrast with the adjacent gloom. the smaller and more attenuated clouds were intensely illuminated throughout. across other inky masses were drawn zigzag bars of radiance which resembled streaks of lightning. the firmament between the clouds faded from a blood-red through orange and daffodil into an exquisite green, which spread like a sea of glory through which those magnificent argosies slowly sailed. some of the clouds were drawn in straight chords across the arch of heaven, these being doubtless the sections of layers of cloud whose horizontal dimensions were hidden from us. the cumuli around and near the sun himself could not be gazed upon, until, as the day declined, they gradually lost their effulgence and became tolerable to the eyes. all was calm--but there was a wildness in the sky like that of anger, which boded evil passions on the part of the atmosphere. the sun at length sank behind the hills, but for some time afterwards carmine clouds swung themselves on high, and cast their ruddy hues upon the mountain snows. duskier and colder waxed the west, colder and sharper the breeze of evening upon the grands mulets, and as twilight deepened towards night, and the stars commenced to twinkle through the chilled air, we retired from the scene. [sidenote: storm on the grands mulets. .] the anticipated storm at length gave notice of its coming. the sea-waves, as observed by aristotle, sometimes reach the shore before the wind which produces them is felt; and here the tempest sent out its precursors, which broke in detached shocks upon the cabin before the real storm arrived. billows of air, in ever quicker succession, rolled over us with a long surging sound, rising and falling as crest succeeded trough and trough succeeded crest. and as the pulses of a vibrating body, when their succession is quick enough, blend to a continuous note, so these fitful gusts linked themselves finally to a storm which made its own wild music among the crags. grandly it swelled, carrying the imagination out of doors, to the clouds and darkness, to the loosened avalanches and whirling snow upon the mountain heads. moored to the rock on two sides, the cabin stood firm, and its manifest security allowed the mind the undisturbed enjoyment of the atmospheric war. we were powerfully shaken, but had no fear of being uprooted; and a certain grandeur of the heart rose responsive to the grandeur of the storm. mounting higher and higher, it at length reached its maximum strength, from which it lowered fitfully, until at length, with a melancholy wail, it bade our rock farewell. a little before half-past one we issued from the cabin. the night being without a moon, we carried three lanterns. the heavens were crowded with stars, among which, however, angry masses of cloud here and there still wandered. the storm, too, had left a rear-guard behind it; and strong gusts rolled down upon us at intervals, at one time, indeed, so violent as to cause balmat to express doubts of our being able to reach the summit. with a thick handkerchief bound around my hat and ears i enjoyed the onset of the wind. once, turning my head to the left, i saw what appeared to me to be a huge mass of stratus cloud, at a great distance, with the stars shining over it. in another instant a precipice of _névé_ loomed upon us; we were close to its base, and along its front the annual layers were separated from each other by broad dark bands. through the gloom it appeared like a cloud, the lines of bedding giving to it the stratus character. [sidenote: a comet discovered. .] immediately before lying down on the previous evening i had opened the little window of the cabin to admit some air. in the sky in front of me shone a curious nodule of misty light with a pale train attached to it. in , on the side of the brocken, i had observed, without previous notice, a comet discovered a few days previously by a former fellow student, and here was another "discovery" of the same kind. i inspected the stranger with my telescope, and assured myself that it was a comet. mr. wills chanced to be outside at the time, and made the same observation independently. as we now advanced up the mountain its ominous light gleamed behind us, while high up in heaven to our left the planet jupiter burned like a lamp of intense brightness. the petit plateau forms a kind of reservoir for the avalanches of the dôme du goûter, and this year the accumulation of frozen débris upon it was enormous. we could see nothing but the ice-blocks on which the light of the lanterns immediately fell; we only knew that they had been discharged from the _séracs_, and that similar masses now rose threatening to our right, and might at any moment leap down upon us. balmat commanded silence, and urged us to move across the plateau with all possible celerity. the warning of our guide, the wild and rakish appearance of the sky, the spent projectiles at our feet, and the comet with its "horrid hair" behind, formed a combination eminently calculated to excite the imagination. [sidenote: dawn on the grand plateau. .] and now the sky began to brighten towards dawn, with that deep and calm beauty which suggests the thought of adoration to the human mind. helped by the contemplation of the brightening east, which seemed to lend lightness to our muscles, we cheerily breasted the steep slope up to the grand plateau. the snow here was deep, and each of our porters took the lead in turn. we paused upon the grand plateau and had breakfast; digging, while we halted, our feet deeply into the snow. thence up to the corridor, by a totally different route from that pursued by mr. hirst and myself the year previously; the slope was steep, but it had not a precipice for its boundary. deep steps were necessary for a time, but when we reached the summit our ascent became more gentle. the eastern sky continued to brighten, and by its illumination the grand plateau and its bounding heights were lovely beyond conception. the snow was of the purest white, and the glacier, as it pushed itself on all sides into the basin, was riven by fissures filled with a coerulean light, which deepened to inky gloom as the vision descended into them. the edges were overhung with fretted cornices, from which depended long clear icicles, tapering from their abutments like spears of crystal. the distant fissures, across which the vision ranged obliquely without descending into them, emitted that magical firmamental shimmer which, contrasted with the pure white of the snow, was inexpressibly lovely. near to us also grand castles of ice reared themselves, some erect, some overturned, with clear cut sides, striped by the courses of the annual snows, while high above the _séracs_ of the plateau rose their still grander brothers of the dôme du goûter. there was a nobility in this glacier scene which i think i have never seen surpassed;--a strength of nature, and yet a tenderness, which at once raised and purified the soul. the gush of the direct sunlight could add nothing to this heavenly beauty; indeed i thought its yellow beams a profanation as they crept down from the humps of the dromedary, and invaded more and more the solemn purity of the realm below. [sidenote: balmat in danger. .] our way lay for a time amid fine fissures with blue walls, until at length we reached the edge of one which elicited other sentiments than those of admiration. it must be crossed. at the opposite side was a high and steep bank of ice which prolonged itself downwards, and ended in a dependent eave of snow which quite overhung the chasm, and reached to within about a yard of our edge of the crevasse. balmat came forward with his axe, and tried to get a footing on the eave: he beat it gently, but the axe went through the snow, forming an aperture through which the darkness of the chasm was rendered visible. our guide was quite free, without rope or any other means of security; he beat down the snow so as to form a kind of stirrup, and upon this he stepped. the stirrup gave way, it was right over the centre of the chasm, but with wonderful tact and coolness he contrived to get sufficient purchase from the yielding mass to toss himself back to the side of the chasm. the rope was now brought forward and tied round the waist of one of the porters; another step was cautiously made in the eave of snow, the man was helped across, and lessened his own weight by means of his hatchet. he gradually got footing on the face of the steep, which he mounted by escaliers; and on reaching a sufficient height he cut two large steps in which his feet might rest securely. here he laid his breast against the sloping wall, and another person was sent forward, who drew himself up by the rope which was attached to the leader. thus we all passed, each of us in turn bearing the strain of his successor upon the rope; it was our last difficulty, and we afterwards slowly plodded through the snow of the corridor towards the base of the mur de la côte. [sidenote: storm on mont blanc. .] [sidenote: thermometer buried. .] climbing zigzag, we soon reached the summit of the mur, and immediately afterwards found ourselves in the midst of cold drifting clouds, which obscured everything. they dissolved for a moment and revealed to us the sunny valley of chamouni; but they soon swept down again and completely enveloped us. upon the calotte, or last slope, i felt no trace of the exhaustion which i had experienced last year, but enjoyed free lungs and a quiet heart. the clouds now whirled wildly round us, and the fine snow, which was caught by the wind and spit bitterly against us, cut off all visible communication between us and the lower world. as we approached the summit the air thickened more and more, and the cold, resulting from the withdrawal of the sunbeams, became intense. we reached the top, however, in good condition, and found the new snow piled up into a sharp _arête_, and the summit of a form quite different from that of the _dos d'un ane_, which it had presented the previous year. leaving balmat to make a hole for the thermometer, i collected a number of bâtons, drove them into the snow, and, drawing my plaid round them, formed a kind of extempore tent to shelter my boiling-water apparatus. the covering was tightly held, but the snow was as fine and dry as dust, and penetrated everywhere: my lamp could not be secured from it, and half a box of matches was consumed in the effort to ignite it. at length it did flame up, and carried on a sputtering combustion. the cold of the snow-filled boiler condensing the vapour from the lamp gradually produced a drop, which, when heavy enough to detach itself from the vessel, fell upon the flame and put it out. it required much patience and the expenditure of many matches to relight it. meanwhile the absence of muscular action caused the cold to affect our men severely. my beard and whiskers were a mass of clotted ice. the bâtons were coated with ice, and even the stem of my thermometer, the bulb of which was in hot water, was covered by a frozen enamel. the clouds whirled, and the little snow granules hit spitefully against the skin wherever it was exposed. the temperature of the air was ° fahr. below the freezing point. i was too intent upon my work to heed the cold much, but i was numbed; one of my fingers had lost sensation, and my right heel was in pain: still i had no thought of forsaking my observation until mr. wills came to me and said that we must return speedily, for balmat's hands were _gelées_. i did not comprehend the full significance of the word; but, looking at the porters, they presented such an aspect of suffering that i feared to detain them longer. they looked like worn old men, their hair and clothing white with snow, and their faces blue, withered, and anxious-looking. the hole being ready, i asked balmat for the magnet to arrange the index of the thermometer: his hands seemed powerless. i struck my tent, deposited the instrument, and, as i watched the covering of it up, some of the party, among whom were mr. wills and balmat, commenced the descent.[a] [sidenote: balmat frostbitten. .] i followed them speedily. midway down the calotte i saw balmat, who was about a hundred yards in advance of me, suddenly pause and thrust his hands into the snow, and commence rubbing them vigorously. the suddenness of the act surprised me, but i had no idea at the time of its real significance: i soon came up to him; he seemed frightened, and continued to beat and rub his hands, plunging them, at quick intervals, into the snow. still i thought the thing would speedily pass away, for i had too much faith in the man's experience to suppose that he would permit himself to be seriously injured. but it did not pass as i hoped it would, and the terrible possibility of his losing his hands presented itself to me. he at length became exhausted by his own efforts, staggered like a drunken man, and fell upon the snow. mr. wills and myself took each a hand, and continued the process of beating and rubbing. i feared that we should injure him by our blows, but he continued to exclaim, "n'ayez pas peur, frappez toujours, frappez fortement!" we did so, until mr. wills became exhausted, and a porter had to take his place. meanwhile balmat pinched and bit his fingers at intervals, to test their condition; but there was no sensation. he was evidently hopeless himself; and, seeing him thus, produced an effect upon me that i had not experienced since my boyhood--my heart swelled, and i could have wept like a child. the idea that i should be in some measure the cause of his losing his hands was horrible to me; schemes for his support rushed through my mind with the usual swiftness of such speculations, but no scheme could restore to him his lost hands. at length returning sensation in one hand announced itself by excruciating pain. "je souffre!" he exclaimed at intervals--words which, from a man of his iron endurance, had a more than ordinary significance. but pain was better than death, and, under the circumstances, a sign of improvement. we resumed our descent, while he continued to rub his hands with snow and brandy, thrusting them at every few paces into the mass through which we marched. at chamouni he had skilful medical advice, by adhering to which he escaped with the loss of six of his nails--his hands were saved. i cannot close this recital without expressing my admiration of the dauntless bearing of our porters, and of the cheerful and efficient manner in which they did their duty throughout the whole expedition. their names are edouard bellin, joseph favret, michel payot, joseph folliguet, and alexandre balmat. footnotes: [a] in august, , i found the temperature of water, boiling in an open vessel at the summit of mont blanc, to be . ° fahr. on that occasion also, though a laborious search was made for the thermometer, it could not be found. ( .) [sidenote: procÈs-verbal. .] the hostility of the chief guide to the expedition was not diminished by the letter of the intendant; and he at once entered a _procès-verbal_ against balmat and his companions on their return to chamouni. i felt that the power thus vested in an unlettered man to arrest the progress of scientific observations was so anomalous, that the enlightened and liberal government of sardinia would never tolerate such a state of things if properly represented to it. the british association met at leeds that year, and to it, as a guardian of science, my thoughts turned. i accordingly laid the case before the association, and obtained its support: a resolution was unanimously passed "that application be made to the sardinian authorities for increased facilities for making scientific observations in the alps." considering the arduous work which balmat had performed in former years in connexion with the glaciers, and especially his zeal in determining, under the direction of professor forbes, their winter motion--for which, as in the case above recorded, he refused all personal remuneration--i thought such services worthy of some recognition on the part of the royal society. i suggested this to the council, and was met by the same cordial spirit of co-operation which i had previously experienced at leeds. a sum of five-and-twenty guineas was at once voted for the purchase of a suitable testimonial; and a committee, consisting of sir roderick murchison, professor forbes, and myself, was appointed to carry the thing out. balmat was consulted, and he chose a photographic apparatus, which, with a suitable inscription, was duly presented to him. [sidenote: british association. .] thus fortified, i drew up an account of what had occurred at chamouni during my last visit, accompanied by a brief statement of the changes which seemed desirable. this was placed in the hands of the president of the british association, to whose prompt and powerful co-operation in this matter every alpine explorer who aspires to higher ground than ordinary is deeply indebted. the following letter assured me that the facility applied for by the british association would be granted by the sardinian government, and that future men of science would find in the alps a less embarrassed field of operations than had fallen to my lot in the summer of . [sidenote: the president's letter. .] " , hertford-street, mayfair, w., "february th, . "my dear sir,-- "having, as i informed you in my last note, communicated with the sardinian minister plenipotentiary the day after receiving your statement relative to the guides at chamouni, i have been favoured by replies from the minister, of the th and th february. in the first the marquis d'azeglio assures me that he will bring the subject before the competent authorities at turin, accompanying the transmission 'd'une récommandation toute spéciale.' in the second letter the marquis informs me that 'the preparation of new regulations for the guides at chamouni had for some time occupied the attention of the minister of the interior, and that these regulations will be in rigorous operation, in all probability, at the commencement of the approaching summer.' the marquis adds that, 'as the regulations will be based upon a principle of much greater liberty, he has every reason to believe that they will satisfy all the desires of travellers in the interests of science.' "with much pleasure at the opportunity of having been in any degree able to bring about the fulfilment of your wishes on the subject, "i remain, my dear sir, "faithfully yours, "richard owen. "pres. brit. association. "prof. tyndall, f.r.s." it ought to be stated that, previous to my arrival at chamouni in , an extremely cogent memorial drawn up by mr. john ball had been presented to the marquis d'azeglio by a deputation from the alpine club. it was probably this memorial which first directed the attention of the sardinian minister of the interior to the subject. winter expedition to the mer de glace, . ( .) having ten days at my disposal last christmas, i was anxious to employ them in making myself acquainted with the winter aspects and phenomena of the mer de glace. on wednesday, the st of december, i accordingly took my place to paris, but on arriving at folkestone found the sea so tempestuous that no boat would venture out. [sidenote: first defeat, and fresh attempt. .] the loss of a single day was more than i could afford, and this failure really involved the loss of two. seeing, therefore, the prospect of any practical success so small, i returned to london, purposing to give the expedition up. on the following day, however, the weather lightened, and i started again, reaching paris on friday morning. on that day it was not possible to proceed beyond macon, where, accordingly, i spent the night, and on the following day reached geneva. much snow had fallen; at paris it still cumbered the streets, and round about macon it lay thick, as if a more than usually heavy cloud had discharged itself on that portion of the country. between macon and roussillon it was lighter, but from the latter station onwards the quantity upon the ground gradually increased. [sidenote: geneva to chamouni. .] on christmas morning, at o'clock, i left geneva by the diligence for sallenches. the dawn was dull, but the sky cleared as the day advanced, and finally a dome of cloudless blue stretched overhead. the mountains were grand; their sunward portions of dazzling whiteness, while the shaded sides, in contrast with the blue sky behind them, presented a ruddy, subjective tint. the brightness of the day reached its maximum towards one o'clock, after which a milkiness slowly stole over the heavens, and increased in density until finally a drowsy turbidity filled the entire air. the distant peaks gradually blended with the white atmosphere above them and lost their definition. the black pine forests on the slopes of the mountains stood out in strong contrast to the snow; and, when looked at through the spaces enclosed by the tree branches at either side of the road, they appeared of a decided indigo-blue. it was only when thus detached by a vista in front that the blue colour was well seen, the air itself between the eye and the distant pines being the seat of the colour. goethe would have regarded it as an excellent illustration of his 'farbenlehre.' we reached sallenches a little after p.m., where i endeavoured to obtain a sledge to continue my journey. a fit one was not to be found, and a carriage was therefore the only resort. we started at five; it was very dark, but the feeble reflex of the snow on each side of the road was preferred by the postilion to the light of lamps. unlike the enviable ostrich, i cannot shut my eyes to danger when it is near: and as the carriage swayed towards the precipitous road side, i could not fold myself up, as it was intended i should, but, quitting the interior and divesting my limbs of every encumbrance, i took my seat beside the driver, and kept myself in readiness for the spring, which in some cases appeared imminent. my companion however was young, strong, and keen-eyed; and though we often had occasion for the exercise of the quality last mentioned, we reached servoz without accident. [sidenote: desolation. .] [sidenote: a horse in the snow. .] here we baited, and our progress afterwards was slow and difficult. the snow on the road was deep and hummocky, and the strain upon the horses very great. having crossed the arve at the pont-pelissier, we both alighted, and i went on in advance. the air was warm, and not a whisper disturbed its perfect repose. there was no moon, and the heavy clouds, which now quite overspread the heavens, cut off even the feeble light of the stars. the sound of the arve, as it rushed through the deep valley to my left, came up to me through crags and trees with a sad murmur. sometimes on passing an obstacle, the sound was entirely cut off, and the consequent silence was solemn in the extreme. it was a churchyard stillness, and the tall black pines, which at intervals cast their superadded gloom upon the road, seemed like the hearse-plumes of a dead world. i reached a wooden hut, where a lame man offers bâtons, minerals, and _eau de vie_, to travellers in summer. it was forsaken, and half buried in the snow. i leaned against the door, and enjoyed for a time the sternness of the surrounding scene. my conveyance was far behind, and the intermittent tinkle of the horses' bells, which augmented instead of diminishing the sense of solitude, informed me of the progress and the pauses of the vehicle. at the summit of the road i halted until my companion reached me; we then both remounted, and proceeded slowly towards les ouches. we passed some houses, the aspect of which was even more dismal than that of nature; their roofs were loaded with snow, and white buttresses were reared against the walls. there was no sound, no light, no voice of joy to indicate that it was the pleasant christmas time. we once met the pioneer of a party of four drunken peasants: he came right against us, and the coachman had to pull up. planting his feet in the snow and propping himself against the leader's shoulder, the bacchanal exhorted the postilion to drive on; the latter took him at his word, and overturned him in the snow. after this we encountered no living thing. the horses seemed seized by a kind of torpor, and leaned listlessly against each other; vainly the postilion endeavoured to rouse them by word and whip; they sometimes essayed to trot down the slopes, but immediately subsided to their former monotonous crawl. as we ascended the valley, the stillness of the air was broken at intervals by wild storm-gusts, sent down against us from mont blanc himself. these chilled me, so i quitted the carriage, and walked on. not far from chamouni, the road, for some distance, had been exposed to the full action of the wind, and the snow had practically erased it. its left wall was completely covered, while a few detached stones, rising here and there above the surface, were the only indications of the presence and direction of the right-hand wall. i could not see the state of the surface, but i learned by other means that the snow had been heaped in oblique ridges across my path. i staggered over four or five of these in succession, sinking knee-deep, and finally found myself immersed to the waist. this made me pause; i thought i must have lost the road, and vainly endeavoured to check myself by the positions of surrounding objects. i turned back and met the carriage: it had stuck in one of the ridges; one horse was down, his hind legs buried to the haunches, his left fore leg plunged to the shoulder in snow, and the right one thrown forward upon the surface. _c'est bien la route?_ demanded my companion. i went back exploring, and assured myself that we were over the road; but i recommended him to release the horses and leave the carriage to its fate. he, however, succeeding in extricating the leader, and while i went on in advance seeking out the firmer portions of the road, he followed, holding his horses by their heads; and half an hour's struggle of this kind brought us to chamouni. [sidenote: chamouni on christmas night. .] it also was a little "city of the dead." there was no living thing in the streets, and neither sound nor light in the houses. the fountain made a melancholy gurgle, one or two loosened window-shutters creaked harshly in the wind, and banged against the objects which limited their oscillations. the hôtel de l'union, so bright and gay in summer, was nailed up and forsaken; and the cross in front of it, stretching its snow-laden arms into the dim air, was the type of desolation. we rang the bell at the hôtel royal, but the bay of a watch-dog resounding through the house was long our only reply. the bell appeared powerless to wake the sleepers, and its sound mingled dismally with that of the wind howling through the deserted passages. the noise of my boot-heel, exerted long on the front door, was at length effective; it was unbarred, and the physical heat of a good stove soon added itself to the warmth of the welcome with which my hostess greeted me. december th.--the snow fell heavily, at frequent intervals, throughout the entire day. dense clouds draped all the mountains, and there was not the least prospect of my being able to see across the mer de glace. i walked out alone in the dim light, and afterwards traversed the streets before going to bed. they were quite forsaken. cold and sullen the arve rolled under its wooden bridge, while the snow fell at intervals with heavy shock from the roofs of the houses, the partial echoes from the surfaces of the granules combining to render the sound loud and hollow. thus were the concerns of this little hamlet changed and fashioned by the obliquity of the earth's axis, the chain of dependence which runs throughout creation, linking the roll of a planet alike with the interests of marmots and of men. [sidenote: ascent of the mountain. .] [sidenote: snow on the pines. .] tuesday, th december.--i rose at six o'clock, having arranged with my men to start at seven, if the weather at all permitted. edouard simond, my old assistant of , and joseph tairraz were the guides of the party; the porters were edouard balmat, joseph simond (fils d'auguste), françois ravanal, and another. they came at the time appointed; it was snowing heavily, and we agreed to wait till eight o'clock and then decide. they returned at eight, and finding them disposed to try the ascent to the montanvert, it was not my place to baulk them. through the valley the work was easy, as the snow had been partially beaten down, but we soon passed the habitable limits, and had to break ground for ourselves. three of my men had tried to reach the montanvert by _la filia_ on the previous thursday, but their experience of the route had been such as to deter them from trying it again. we now chose the ordinary route, breasting the slope until we reached the cluster of chalets, under the projecting eave of one of which the men halted and applied "pattens" to their feet. these consisted of planks about sixteen inches long and ten wide, which were firmly strapped to the feet. my first impression was that they were worse than useless, for though they sank less deeply than the unarmed feet, on being raised they carried with them a larger amount of snow, which, with the leverage of the leg, appeared to necessitate an enormous waste of force. i stated this emphatically, but the men adhered to their pattens, and before i reached the montanvert i had reason to commend their practice as preferable to my theory. i was however guided by the latter, and wore no pattens. the general depth of the snow along the track was over three feet; the footmarks of the men were usually rigid enough to bear my weight, but in many cases i went through the crust which their pressure had produced, and sank suddenly in the mass. the snow became softer as we ascended, and my immersions more frequent, but the work was pure enjoyment, and the scene one of extreme beauty. the previous night's snow had descended through a perfectly still atmosphere, and had loaded all the branches of the pines; the long arms of the trees drooped under the weight, and presented at their extremities the appearance of enormous talons turned downwards. some of the smaller and thicker trees were almost entirely covered, and assumed grotesque and beautiful forms; the upper part of one in particular resembled a huge white parrot with folded wings and drooping head, the slumber of the bird harmonizing with the torpor of surrounding nature. i have given a sketch of it in fig. . [illustration: fig. . snow on the pines.] [sidenote: sound of breaking snow. .] previous to reaching the half-way spring, where the peasant girls offer strawberries to travellers in summer, we crossed two large couloirs filled with the débris of avalanches which had fallen the night before. between these was a ridge forty or fifty yards wide on which the snow was very deep, the slope of the mountain also adding a component to the fair thickness of the snow. my shoulder grazed the top of the embankment to my right as i crossed the ridge, and once or twice i found myself waist deep in a vertical shaft from which it required a considerable effort to escape. suddenly we heard a deep sound resembling the dull report of a distant gun, and at the same moment the snow above us broke across, forming a fissure parallel to our line of march. the layer of snow had been in a state of strain, which our crossing brought to a crisis: it gave way, but having thus relieved itself it did not descend. several times during the ascent the same phenomenon occurred. once, while engaged upon a very steep slope, one of the men cried out to the leader, "_arrêtez!_" immediately in front of the latter the snow had given way, forming a zigzag fissure across the slope. we all paused, expecting to see an avalanche descend. tairraz was in front; he struck the snow with his bâton to loosen it, but seeing it indisposed to descend he advanced cautiously across it, and was followed by the others. i brought up the rear. the steepness of the mountain side at this place, and the absence of any object to which one might cling, would have rendered a descent with the snow in the last degree perilous, and we all felt more at ease when a safe footing was secured at the further side of the incline. at the spring, which showed a little water, the men paused to have a morsel of bread. the wind had changed, the air was clearing, and our hopes brightening. as we ascended the atmosphere went through some extraordinary mutations. clouds at first gathered round the aiguille and dôme du goûter, casting the lower slopes of the mountain into intense gloom. after a little time all this cleared away, and the beams of the sun striking detached pieces of the slopes and summits produced an extraordinary effect. the aiguille and dôme were most singularly illumined, and to the extreme left rose the white conical hump of the dromedary, from which a long streamer of snow-dust was carried southward by the wind. the aiguille du dru, which had been completely mantled during the earlier part of the day, now threw off its cloak of vapour and rose in most solemn majesty before us; half of its granite cone was warmly illuminated, and half in shadow. the wind was high in the upper regions, and, catching the dry snow which rested on the asperities and ledges of the aiguille, shook it out like a vast banner in the air. the changes of the atmosphere, and the grandeur which they by turns revealed and concealed, deprived the ascent of all weariness. we were usually flanked right and left by pines, but once between the fountain and the montanvert we had to cross a wide unsheltered portion of the mountain which was quite covered with the snow of recent avalanches. this was lumpy and far more coherent than the undisturbed snow. we took advantage of this, and climbed zigzag over the avalanches for three-quarters of an hour, thus reaching the opposite pines at a point considerably higher than the path. this, though not the least dangerous, was the least fatiguing part of the ascent. [sidenote: colour of snow. .] i frequently examined the colour of the snow: though fresh, its blue tint was by no means so pronounced as i have seen it on other occasions; still it was beautiful. the colour is, no doubt, due to the optical reverberations which occur within a fissure or cavity formed in the snow. the light is sent from side to side, each time plunging a little way into the mass; and being ejected from it by reflection, it thus undergoes a sifting process, and finally reaches the eye as blue light. the presence of any object which cuts off this cross-fire of the light destroys the colour. i made conical apertures in the snow, in some cases three feet deep, a foot wide at the mouth, and tapering down to the width of my bâton. when the latter was placed along the axis of such a cone, the blue light which had previously filled the cavity disappeared; on the withdrawal of the bâton it was followed by the light, and thus by moving the staff up and down its motions were followed by the alternate appearance and extinction of the light. i have said that the holes made in the snow seemed filled with a blue light, and it certainly appeared as if the air contained in the cavities had itself been coloured, and thereby rendered visible, the vision plunging into it as into a blue medium. another fact is perhaps worth notice: snow rarely lies so smooth as not to present little asperities at its surface; little ridges or hillocks, with little hollows between them. such small hollows resemble, in some degree, the cavities which i made in the snow, and from them, in the present instance, a delicate light was sent to the eye, faintly tinted with the pure blue of the snow-crystals. in comparison with the spots thus illuminated, the little protuberances were gray. the portions most exposed to the light seemed least illuminated, and their defect in this respect made them appear as if a light-brown dust had been strewn over them. [sidenote: the montanvert in winter. .] after five hours and a half of hard work we reached the montanvert. i had often seen it with pleasure. often, having spent the day alone amid the _séracs_ of the col du géant, on turning the promontory of trélaporte on my way home, the sight of the little mansion has gladdened me, and given me vigour to scamper down the glacier, knowing that pleasant faces and wholesome fare were awaiting me. this day, also, the sight of it was most welcome, despite its desolation. the wind had swept round the auberge, and carried away its snow-buttresses, piling the mass thus displaced against the adjacent sheds, to the roofs of which one might step from the surface of the snow. the floor of the little château in which i lodged in was covered with snow, and on it were the fresh footmarks of a little animal--a marmot might have made such marks, had not the marmots been all asleep--what the creature was i do not know. [sidenote: crystal curtain. .] in the application of her own principles, nature often transcends the human imagination; her acts are bolder than our predictions. it is thus with the motion of glaciers; it was thus at the montanvert on the day now referred to. the floors, even where the windows appeared well closed, were covered with a thin layer of fine snow; and some of the mattresses in the bedrooms were coated to the depth of half an inch with this fine powder. given a chink through which the finest dust can pass, dry snow appears competent to make its way through the same fissure. it had also been beaten against the windows, and clung there like a ribbed drapery. in one case an effect so singular was exhibited, that i doubted my eyes when i first saw it. in front of a large pane of glass, and quite detached from it, save at its upper edge, was a festooned curtain formed entirely of minute ice-crystals. it appeared to be as fine as muslin; the ease of its curves and the depth of its folds being such as could not be excelled by the intentional arrangement of ordinary gauze. the frost-figures on some of the window-panes were also of the most extraordinary character: in some cases they extended over large spaces, and presented the appearance which we often observe in london; but on other panes they occurred in detached clusters, or in single flowers, these grouping themselves together to form miniature bouquets of inimitable beauty. i placed my warm hand against a pane which was covered by the crystallization, and melted the frostwork which clung to it. i then withdrew my hand and looked at the film of liquid through a pocket-lens. the glass cooled by contact with the air, and after a time the film commenced to move at one of its edges; atom closed with atom, and the motion ran in living lines through the pellicle, until finally the entire film presented the beauty and delicacy of an organism. the connexion between such objects and what we are accustomed to call the feelings may not be manifest, but it is nevertheless true that, besides appealing to the pure intellect of man, these exquisite productions can also gladden his heart and moisten his eyes. [sidenote: the mer de glace in winter. .] the glacier excited the admiration of us all: not as in summer, shrunk and sullied like a spent reptile, steaming under the influence of the sun; its frozen muscles were compact, strength and beauty were associated in its aspect. at some places it was pure and smooth; at others frozen fins arose from it, high, steep, and sharply crested. down the opposite mountain side arrested streams set themselves erect in successive terraces, the fronts of which were fluted pillars of ice. there was no sound of water; even the nant blanc, which gushes from a spring, and which some describe as permanent throughout the winter, showed no trace of existence. from the montanvert to trélaporte the mer de glace was all in shadow; but the sunbeams pouring down the corridor of the géant ruled a beam of light across the glacier at its upper portion, smote the base of the aiguille du moine, and flooded the mountain with glory to its crest. at the opposite side of the valley was the aiguille du dru, with a banneret of snow streaming from its mighty cone. the grande jorasse, and the range of summits between it and the aiguille du géant, were all in view, and the charmoz raised its precipitous cliffs to the right, and pierced with its splinter-like pinnacles the clear cold air. as the night drew on, the mountains seemed to close in upon us; and on looking out before retiring to rest, a scene so solemn had never before presented itself to my eyes or affected my imagination. [sidenote: the first night. .] my men occupied the afternoon of the day of our arrival in making a preliminary essay upon the glacier while i prepared my instruments. to the person whom i intended to fix my stations, three others were attached by sound ropes of considerable length. hidden crevasses we knew were to be encountered, and we had made due preparation for them. throughout the afternoon the weather remained fine, and at night the stars shone out, but still with a feeble lustre. i could notice a turbidity gathering in the air over the range of the brévent, which seemed disposed to extend itself towards us. at night i placed a chair in the middle of the snow, at some distance from the house, and laid on it a registering thermometer. a bountiful fire of pine logs was made in the _salle à manger_; a mattress was placed with its foot towards the fire, its middle line bisecting the right angle in which the fireplace stood; this being found by experiment to be the position in which the draughts from the door and from the windows most effectually neutralized each other. in this region of calms i lay down, and covering myself with blankets and duvets, listened to the crackling of the logs, and watched their ruddy flicker upon the walls, until i fell asleep. the wind rose during the night, and shook the windows: one pane in particular seemed set in unison to the gusts, and responded to them by a loud and melodious vibration. i rose and wedged it round with _sous_ and penny pieces, and thus quenched its untimely music. december th.--we were up before the dawn. tairraz put my fire in order, and i then rose. the temperature of the room at a distance of eight feet from the fire was two degrees of centigrade below zero; the lowest temperature outside was eleven degrees of centigrade below zero,--not at all an excessive cold. the clouds indeed had, during the night, thrown vast diaphragms across the sky, and thus prevented the escape of the earth's heat into space. while my assistants were preparing breakfast i had time to inspect the glacier and its bounding heights. on looking up the mer de glace, the grande jorasse meets the view, rising in steep outline from the wall of cliffs which terminates the glacier de léchaud. behind this steep ascending ridge, which is shown on the frontispiece, and upon it, a series of clouds had ranged themselves, stretching lightly along the ridge at some places, and at others collecting into ganglia. a string of rosettes was thus formed which were connected together by gauzy filaments. the portion of the heavens behind the ridge was near the domain of the rising sun, and when he cleared the horizon his red light fell upon the clouds, and ignited them to ruddy flames. some of the lighter clouds doubled round the summit of the mountain, and swathed its black crags with a vestment of transparent red. the adjacent sky wore a strange and supernatural air; indeed there was something in the whole scene which baffled analysis, and the words of tennyson rose to my lips as i gazed upon it:-- [sidenote: a "rose of dawn." .] "god made himself an awful rose of dawn." i have spoken several times of the cloud-flag which the wind wafted from the summit of the aiguille du dru. on the present occasion this grand banner reached extraordinary dimensions. it was brindled in some places as if whipped into curds by the wind; but through these continuous streamers were drawn, which were bent into sinuosities resembling a waving flag at a mast-head. all this was now illuminated with the sun's red rays, which also fringed with fire the exposed edges and pinnacles both of the aiguille du dru and the aiguille verte. thus rising out of the shade of the valley the mountains burned like a pair of torches, the flames of which were blown half a mile through the air. soon afterwards the summits of the aiguilles rouges were illuminated, and day declared itself openly among the mountains. [sidenote: the stakes fixed. .] but these red clouds of the morning, magnificent though they were, suggested thoughts which tended to qualify the pleasure which they gave: they did not indicate good weather. sometimes, indeed, they had to fight with denser masses, which often prevailed, swathing the mountains in deep neutral tint, but which, again yielding, left the glory of the sunrise augmented by contrast with their gloom. between eight and nine a.m. we commenced the setting out of our first line, one of whose termini was a point about a hundred yards higher up than the montanvert hotel; a withered pine on the opposite mountain side marking the other terminus. the stakes made use of were four feet long. with the selfsame bâton which i had employed upon the mer de glace in , and which simond had preserved, the worthy fellow now took up the line. at some places the snow was very deep, but its lower portions were sufficiently compact to allow of a stake being firmly fixed in it. at those places where the wind had removed the snow or rendered it thin, the ice was pierced with an auger and the stake driven into it. the greatest caution was of course necessary on the part of the men; they were in the midst of concealed crevasses, and sounding was essential at every step. by degrees they withdrew from me, and approached the eastern boundary of the glacier, where the ice was greatly dislocated, and the labour of wading through the snow enormous. long détours were sometimes necessary to reach a required point; but they were all accomplished, and we at length succeeded in fixing eleven stakes along this line, the most distant of which was within about eighty yards of the opposite side of the glacier. [sidenote: storm on the glacier. .] the men returned, and i consulted them as to the possibility of getting a line across at the _ponts_; but this was judged to be impossible in the time. we thought, however, that a second line might be staked out at some distance below the montanvert. i took the theodolite down the mountain-slope, wading at times breast-deep in snow, and having selected a line, the men tied themselves together as before, and commenced the staking out. the work was slowly but steadily and steadfastly done. the air darkened; angry clouds gathered around the mountains, and at times the glacier was swept by wild squalls. the men were sometimes hidden from me by the clouds of snow which enveloped them, but between those intermittent gusts there were intervals of repose, which enabled us to prosecute our work. this line was more difficult than the first one; the glacier was broken into sharp-edged chasms; the ridges to be climbed were steep, and the snow which filled the depressions profound. the oblique arrangement of the crevasses also magnified the labour by increasing the circuits. i saw the leader of the party often shoulder-deep in snow, treading the soft mass as a swimmer walks in water, and i felt a wish to be at his side to cheer him and to share his toil. each man there, however, knew my willingness to do this if occasion required it, and wrought contented. at length the last stake being fixed, the faces of the men were turned homeward. the evening became wilder, and the storm rose at times to a hurricane. on the more level portions of the glacier the snow lay deep and unsheltered; among its frozen waves and upon its more dislocated portions it had been partially engulfed, and the residue was more or less in shelter. over the former spaces dense clouds of snow rose, whirling in the air and cutting off all view of the glacier. the whole length of the mer de glace was thus divided into clear and cloudy segments, and presented an aspect of wild and wonderful turmoil. a large pine stood near me, with its lowest branch spread out upon the surface of the snow; on this branch i seated myself, and, sheltered by the trunk, waited until i saw my men in safety. the wind caught the branches of the trees, shook down their loads of snow, and tossed it wildly in the air. every mountain gave a quota to the storm. the scene was one of most impressive grandeur, and the moan of the adjacent pines chimed in noble harmony with the picture which addressed the eyes. at length we all found ourselves in safety within doors. the windows shook violently. the tempest was however intermittent throughout, as if at each effort it had exhausted itself, and required time to recover its strength. as i heard its heralding roar in the gullies of the mountains, and its subsequent onset against our habitation, i thought wistfully of my stations, not knowing whether they would be able to retain their positions in the face of such a blast. that night however, as if the storm had sung our lullaby, we all slept profoundly, having arranged to commence our measurements as early as light permitted on the following day. [sidenote: heavy snow. .] thursday, th december.--"snow, heavy snow: it must have descended throughout the entire night; the quantity freshly fallen is so great; the atmosphere at seven o'clock is thick with the descending flakes." at eight o'clock it cleared up a little, and i proceeded to my station, while the men advanced upon the glacier; but i had scarcely fixed my theodolite when the storm recommenced. i had a man to clear away the snow and otherwise assist me; he procured an old door from the hotel, and by rearing it upon its end sheltered the object-glass of the instrument. added to the flakes descending from the clouds was the spitting snow-dust raised by the wind, which for a time so blinded me that i was unable to see the glacier. the measurement of the first stake was very tedious, but practice afterwards enabled me to take advantage of the brief lulls and periods of partial clearness with which the storm was interfused. [sidenote: a man in a crevasse. .] at nine o'clock my telescope happened to be directed upon the men as they struggled through the snow; all evidence of the deep track which they had formed yesterday having been swept away. i saw the leader sink and suddenly disappear. he had stood over a concealed fissure, the roof of which had given way and he had dropped in. i observed a rapid movement on the part of the remaining three men: they grouped themselves beside the fissure, and in a moment the missing man was drawn from between its jaws. his disappearance and reappearance were both extraordinary. we had, as i have stated, provided for contingencies of this kind, and the man's rescue was almost immediate. [sidenote: six-rayed crystals. .] my attendant brought two poles from the hotel which we thrust obliquely into the snow, causing the free ends to cross each other; over these a blanket was thrown, behind which i sheltered myself from the storm as the men proceeded from stake to stake. at . the storm was so thick that i was unable to see the men at the stake which they had reached at the time; the flakes sped wildly in their oblique course across the field of the telescope. some time afterwards the air became quite still, and the snow underwent a wonderful change. frozen flowers similar to those i had observed on monte rosa fell in myriads. for a long time the flakes were wholly composed of these exquisite blossoms entangled together. on the surface of my woollen dress they were soft as down; the snow itself on which they fell seemed covered by a layer of down; while my coat was completely spangled with six-rayed stars. and thus prodigal nature rained down beauty, and had done so here for ages unseen by man. and yet some flatter themselves with the idea that this world was planned with strict reference to human use; that the lilies of the field exist simply to appeal to the sense of the beautiful in man. true, this result is secured, but it is one of a thousand all equally important in the eyes of nature. whence those frozen blossoms? why for æons wasted? the question reminds one of the poet's answer when asked whence was the rhodora:-- "why wert thou there, o rival of the rose? i never thought to ask, i never knew; but in my simple ignorance suppose the selfsame power that brought me there brought you!"[a] i sketched some of the crystals, but, instead of reproducing these sketches, which were rough and hasty, i have annexed two of the forms drawn with so much skill and patience by mr. glaisher. [illustration: fig. . snow crystals.] [illustration: fig. . snow crystals.] we completed the measurement of the first line before eleven o'clock, and i felt great satisfaction in the thought that i possessed something of which the weather could not deprive me. as i closed my note-book and shifted the instrument to the second station, i felt that my expedition was already a success. at a quarter past eleven i had my theodolite again fixed, and ranging the telescope along the line of pickets, i saw them all standing. crossing the ice wilderness, and suggesting the operation of intelligence amid that scene of desolation, their appearance was pleasant to me. just before i commenced, a solitary jay perched upon the summit of an adjacent pine and watched me. the air was still at the time, and the snow fell heavily. the flowers moreover were magnificent, varying from about the twentieth of an inch to two lines in diameter, while, falling through the quiet air, their forms were perfect. adjacent to my theodolite was a stump of pine, from which i had the snow removed, in order to have something to kick my toes against when they became cold; and on the stump was placed a blanket to be used as a screen in case of need. while i remained at the station a layer of snow an inch thick fell upon this blanket, the whole layer being composed of these exquisite flowers. the atmosphere also was filled with them. from the clouds to the earth nature was busy marshalling her atoms, and putting to shame by the beauty of her structures the comparative barbarities of art. [sidenote: sound through the snow-storm. .] my men at length reached the first station, and the measurement commenced. the storm drifted up the valley, thickening all the air as it approached. denser and denser the flakes fell; but still, with care and tact i was able to follow my party to a distance of yards. i had not thought it possible to see so far through so dense a storm. at this distance also my voice could be heard, and my instructions understood; for once, as the man who took up the line stood behind his bâton and prevented its projection against the white snow, i called out to him to stand aside, and he promptly did so. throughout the entire measurement the snow never ceased falling, and some of the illusions which it produced were extremely singular. the distant boundary of the glacier appeared to rise to an extraordinary height, and the men wading through the snow appeared as if climbing up a wall. the labour along this line was still greater than on the former; on the steeper slopes especially the toil was great; for here the effort of the leader to lift his own body added itself to that of cutting his way through the snow. his footing i could see often yielded, and he slid back, checking his recession, however, by still plunging forward; thus, though the limbs were incessantly exerted, it was, for a time, a mere motion of vibration without any sensible translation. at the last stake the men shouted, "_nous avons finis!_" and i distinctly heard them through the falling snow. by this time i was quite covered with the crystals which clung to my wrapper. they also formed a heap upon my theodolite, rising over the spirit-levels and embracing the lower portion of the vertical arc. the work was done; i struck my theodolite and ascended to the hotel; the greatest depth of snow through which i waded reaching, when i stood erect, to within three inches of my breast. [sidenote: swift descent. .] the men returned; dinner was prepared and consumed; the disorder which we had created made good; the rooms were swept, the mattresses replaced, and the shutters fastened, where this was possible. we locked up the house, and with light hearts and lithe limbs commenced the descent. my aim now was to reach the source of the arveiron, to examine the water and inspect the vault. with this view we went straight down the mountain. the inclinations were often extremely steep, and down these we swept with an avalanche-velocity; indeed usually accompanied by an avalanche of our own creation. on one occasion balmat was for a moment overwhelmed by the descending mass: the guides were startled, but he emerged instantly. tairraz followed him, and i followed tairraz, all of us rolling in the snow at the bottom of the slope as if it were so much flour. my practice on the finsteraarhorn rendered me at home here. one of the porters could by no means be induced to try this flying mode of descent. simond carried my theodolite box, tied upon a crotchet on his back; and once, while shooting down a slope, he incautiously allowed a foot to get entangled; his momentum rolled him over and over down the incline, the theodolite emerging periodically from the snow during his successive revolutions. a succession of _glissades_ brought us with amazing celerity to the bottom of the mountain, whence we picked our way amid the covered boulders and over the concealed arms of the stream to the source of the arveiron. the quantity of water issuing from the vault was considerable, and its character that of true glacier water. it was turbid with suspended matter, though not so turbid as in summer; but the difference in force and quantity would, i think, be sufficient to account for the greater summer turbidity. this character of the water could only be due to the grinding motion of the glacier upon its bed; a motion which seems not to be suspended even in the depth of winter. the temperature of the water was the tenth of a degree centigrade above zero; that of the ice was half a degree below zero: this was also the temperature of the air, while that of the snow, which in some places covered the ice-blocks, was a degree and a quarter below zero. [sidenote: vault of the arveiron. .] the entrance to the vault was formed by an arch of ice which had detached itself from the general mass of the glacier behind: between them was a space through which we could look to the sky above. beyond this the cave narrowed, and we found ourselves steeped in the blue light of the ice. the roof of the inner arch was perforated at one place by a shaft about a yard wide, which ran vertically to the surface of the glacier. water had run down the sides of this shaft, and, being re-frozen below, formed a composite pillar of icicles at least twenty feet high and a yard thick, stretching quite from roof to floor. they were all united to a common surface at one side, but at the other they formed a series of flutings of exceeding beauty. this group of columns was bent at its base as if it had yielded to the forward motion of the glacier, or to the weight of the arch overhead. passing over a number of large ice-blocks which partially filled the interior of the vault, we reached its extremity, and here found a sloping passage with a perfect arch of crystal overhead, and leading by a steep gradient to the air above. this singular gallery was about seventy feet long, and was floored with snow. we crept up it, and from the summit descended by a glissade to the frontal portion of the cavern. to me this crystal cave, with the blue light glistening from its walls, presented an aspect of magical beauty. my delight, however, was tame compared with that of my companions. [sidenote: majestic scene. .] looking from the blue arch westwards, the heavens were seen filled by crimson clouds, with fiery outliers reaching up to the zenith. on quitting the vault i turned to have a last look at those noble sentinels of the mer de glace, the aiguille du dru, and the aiguille verte. the glacier below the mountains was in shadow, and its frozen precipices of a deep cold blue. from this, as from a basis, the mountain cones sprang steeply heavenward, meeting half way down the fiery light of the sinking sun. the right-hand slopes and edges of both pyramids burned in this light, while detached protuberant masses also caught the blaze, and mottled the mountains with effulgent spaces. a range of minor peaks ran slanting downwards from the summit of the aiguille verte; some of these were covered with snow, and shone as if illuminated with the deep crimson of a strontian flame. i was absolutely struck dumb by the extraordinary majesty of this scene, and watched it silently till the red light faded from the highest summits. thus ended my winter expedition to the mer de glace. next morning, starting at three o'clock, i was driven by my two guides in an open sledge to sallenches. the rain was pitiless and the road abominable. the distance, i believe, is only six leagues, but it took us five hours to accomplish it. the leading mule was beyond the reach of simond's whip, and proved a mere obstructive; during part of the way it was unloosed, tied to the sledge, and dragged after it. simond afterwards mounted the hindmost beast and brought his whip to bear upon the leader, the jerking he endured for an hour and a half seemed almost sufficient to dislocate his bones. we reached sallenches half an hour late, but the diligence was behind its time by this exact interval. we met it on the pont st. martin, and i transferred myself from the sledge to the interior. this was the morning of the th of december, and on the evening of the st of january i was in london. [sidenote: my assistants. .] i cannot finish this recital without saying one word about my men. their behaviour was admirable throughout. the labour was enormous, but it was manfully and cheerfully done. i know simond well; he is intelligent, truthful, and affectionate, and there is no guide of my acquaintance for whom i have a stronger regard. joseph tairraz is an extremely intelligent and able guide, and on this trying occasion proved himself worthy of my highest praise and commendation. their two companions upon the glacier, edouard balmat (le petit balmat) and joseph simond (fils d'auguste), acquitted themselves admirably; and it also gives me pleasure to bear testimony to the willing and efficient service of françois ravanal, who attended upon me during the observations. footnotes: [a] emerson. part ii. chiefly scientific. aber im stillen gemach entwirft bedeutende zirkel sinnend der weise, beschleicht forschend den schaffenden geist, prüft der stoffe gewalt, der magnete hassen und lieben, folgt durch die lüfte dem klang, folgt durch den aether dem strahl, sucht das vertraute gesetz in des zufalls grausenden wundern, sucht den ruhenden pol in der erscheinungen flucht. schiller. on light and heat. ( .) [sidenote: theories of light.] what is light? the ancients supposed it to be something emitted by the eyes, and for ages no notion was entertained that it required time to pass through space. in the year römer first proved that the light from jupiter's satellites required a certain time to cross the earth's orbit. bradley afterwards found that, owing to the velocity with which the earth flies through space, the rays of the stars are slightly inclined, just as rain-drops which descend vertically appear to meet us when we move swiftly through the shower. in kew gardens there is a sun-dial commemorative of this discovery, which is called the _aberration of light_. knowing the velocity of the earth, and the inclination of the stellar rays, bradley was able to calculate the velocity of light; and his result agrees closely with that of römer. celestial distances were here involved, but a few years ago m. fizeau, by an extremely ingenious contrivance, determined the time required by light to pass over a distance of about yards; and his experiment is quite in accordance with the results of his predecessors. but what is it which thus moves? some, and among the number newton, imagined light to consist of particles darted out from luminous bodies. this is the so-called emission-theory, which was held by some of the greatest men: laplace, for example, accepted it; and m. biot has developed it with a lucidity and power peculiar to himself. it was first opposed by the astronomer huyghens, and afterwards by euler, both of whom supposed light to be a kind of undulatory motion; but they were borne down by their great antagonists, and the emission-theory held its ground until the commencement of the present century, when thomas young, professor of natural philosophy in the royal institution, reversed the scientific creed by placing the theory of undulation on firm foundations. he was followed by a young frenchman of extraordinary genius, who, by the force of his logic and the conclusiveness of his experiments, left the wave-theory without a competitor. the name of this young frenchman was augustin fresnel. since his time some of the ablest minds in europe have been applied to the investigation of this subject; and thus a mastery, almost miraculous, has been attained over the grandest and most subtle of natural phenomena. true knowledge is always fruitful, and a clear conception regarding any one natural agent leads infallibly to better notions regarding others. thus it is that our knowledge of light has corrected and expanded our knowledge of _heat_, while the latter, in its turn, will assuredly lead us to clearer conceptions regarding the other forces of nature. i think it will not be a useless labour if i here endeavour to state, in a simple manner, our present views of light and heat. such knowledge is essential to the explanation of many of the phenomena referred to in the foregoing pages; and even to the full comprehension of the origin of the glaciers themselves. a few remarks on the nature of sound will form a fit introduction. [sidenote: nature of sound.] it is known that sound is conveyed to our organs of hearing by the air: a bell struck in a vacuum emits no sound, and even when the air is thin the sound is enfeebled. hawksbee proved this by the air-pump; de saussure fired a pistol at the top of mont blanc,--i have repeated the experiment myself, and found, with him, that the sound is feebler than at the sea level. sound is not produced by anything projected through the air. the explosion of a gun, for example, is sent forward by a motion of a totally different kind from that which animates the bullet projected from the gun: the latter is a motion of _translation_; the former, one of _vibration_. to use a rough comparison, sound is projected through the air as a push is through a crowd; it is the propagation of a _wave_ or _pulse_, each particle taking up the motion of its neighbour, and delivering it on to the next. these aërial waves enter the external ear, meet a membrane, the so-called tympanic membrane, which is drawn across the passage at a certain place, and break upon it as sea-waves do upon the shore. the membrane is shaken, its tremors are communicated to the auditory nerve, and transmitted by it to the brain, where they produce the impression to which we give the name of sound. [sidenote: cause of music.] in the tumult of a city, pulses of different kinds strike irregularly upon the tympanum, and we call the effect _noise_; but when a succession of impulses reach the ear _at regular intervals_ we feel the effect as _music_. thus, a vibrating string imparts a series of shocks to the air around it, which are transmitted with perfect regularity to the ear, and produce a _musical note_. when we hear the song of a soaring lark we may be sure that the entire atmosphere between us and the bird is filled with pulses, or undulations, or waves, as they are often called, produced by the little songster's organ of voice. this organ is a vibrating instrument, resembling, in principle, the reed of a clarionet. let us suppose that we hear the song of a lark, elevated to a height of feet in the air. before this is possible, the bird must have agitated a sphere of air feet in diameter; that is to say, it must have communicated to , tons of air a motion sufficiently intense to be appreciated by our organs of hearing. [sidenote: cause of pitch.] musical sounds differ in _pitch_: some notes are high and shrill, others low and deep. boys are chosen as choristers to produce the shrill notes; men are chosen to produce the bass notes. now, the sole difference here is, that the boy's organ vibrates _more rapidly_ than the man's--it sends a greater number of impulses per second to the ear. in like manner, a short string emits a higher note than a long one, because it vibrates more quickly. the greater the number of vibrations which any instrument performs in a given time, the higher will be the pitch of the note produced. the reason why the hum of a gnat is shriller than that of a beetle is that the wings of the small insect vibrate more quickly than those of the larger one. we can, with suitable arrangements, make those sonorous vibrations visible to the eye;[a] and we also possess instruments which enable us to tell, with the utmost exactitude, the number of vibrations due to any particular note. by such instruments we learn that a gnat can execute many thousand flaps of its little wings in a second of time. [sidenote: nature of light.] in the study of nature the coarser phenomena, which come under the cognizance of the senses, often suggest to us the finer phenomena which come under the cognizance of the mind; and thus the vibrations which produce sound, and which, as has been stated, can be rendered visible to the eye by proper means, first suggested that _light_ might be due to a somewhat similar action. this is now the universal belief. a luminous body is supposed to have its atoms, or molecules, in a state of intense vibration. the motions of the atoms are supposed to be communicated to a medium suited to their transmission, as air is to the transmission of sound. this medium is called the _luminiferous ether_, and the little billows excited in it speed through it with amazing celerity, enter the pupil of the eye, pass through the humours, and break upon the retina or optic nerve, which is spread out at the back of the eye. hence the tremors they produce are transmitted along the nerve to the brain, where they announce themselves as _light_. the swiftness with which the waves of light are propagated through the ether, is however enormously greater than that with which the waves of sound pass through the air. an aërial wave of sound travels at about the rate of feet in a second: a wave of light leaves , miles behind it in the same time. [sidenote: cause of colour.] thus, then, in the case of sound, we have the sonorous body, the air, and the auditory nerve, concerned in the phenomenon; in the case of light, we have the luminous body, the ether, and the optic nerve. the fundamental analogy of sound and light is thus before us, and it is easily remembered. but we must push the analogy further. we know that the white light which comes to us from the sun is made up of an infinite number of coloured rays. by refraction with a prism we can separate those rays from each other, and arrange them in the series of colours which constitute the solar spectrum. the rainbow is an imperfect or _impure_ spectrum, produced by the drops of falling rain, but by prisms we can unravel the white light into pure red, orange, yellow, green, blue, indigo, and violet. now, this spectrum is to the eye what the gamut is to the ear; each colour represents a note, and _the different colours represent notes of different pitch_. the vibrations which produce the impression of red are _slower_, and the waves which they produce are _longer_, than those to which we owe the sensation of violet; while the vibrations which excite the other colours are intermediate between these two extremes. this, then, is the second grand analogy between light and sound: _colour answers to pitch_. there is therefore truth in the figure when we say that the gentian of the alps sings a shriller note than the wild rhododendron, and that the red glow of the mountains at sunset is of a lower pitch than the blue of the firmament at noon. [sidenote: length of ethereal waves.] these are not fanciful analogies. to the mind of the philosopher these waves of ether are almost as palpable and certain as the waves of the sea, or the ripples on the surface of a lake. the length of the waves, both of sound and light, and the number of shocks which they respectively impart to the ear and eye, have been the subjects of the strictest measurement. let us here go through a simple calculation. it has been found that , waves of red light placed end to end would make up an inch. how many inches are there in , miles? my youngest reader can make the calculation for himself, and find the answer to be , , , inches. it is evident that, if we multiply this number by , , we shall obtain the number of waves of red light in , miles; this number is , , , , . _all these waves enter the eye in one second_; thus the expression "i see red colour," strictly means, "my eye is now in receipt of four hundred and seventy-four millions of millions of impulses per second." to produce the impression of violet light a still greater number of impulses is necessary; the wave-length of violet is the / th part of an inch, and the number of shocks imparted in a second by waves of this length is, in round numbers, six hundred and ninety-nine millions of millions. the other colours of the spectrum, as already stated, rise gradually in pitch from the red to the violet. a very curious analogy between the eye and ear may here be noticed. the range of seeing is different in different persons--some see a longer spectrum than others; that is to say, rays which are obscure to some are luminous to others. dr. wollaston pointed out a similar fact as regards hearing; the range of which differs in different individuals. savart has shown that a good ear can hear a musical note produced by shocks in a second; it can also hear a note produced by , shocks in a second; but there are ears in which the range is much more limited. it is possible indeed to produce a sound which shall be painfully shrill to one person, while it is quite unheard by another. i once crossed a swiss mountain in company with a friend; a donkey was in advance of us, and the dull tramp of the animal was plainly heard by my companion; but to me this sound was almost masked by the shrill chirruping of innumerable insects which thronged the adjacent grass; my friend heard nothing of this, it lay quite beyond his range of hearing. a third and most important analogy between sound and light is now to be noted; and it will be best understood by reference to something more tangible than either. when a stone is thrown into calm water a series of rings spread themselves around the centre of disturbance. if a second stone be thrown in at some distance from the first, the rings emanating from both centres will cross each other, and at those points where the ridge of one wave coincides with the ridge of another the water will be lifted to a greater height. at those points, on the contrary, where the ridge of one wave crosses the furrow of another, we have both obliterated, and the water restored to its ordinary level. where two ridges or two furrows unite, we have a case of _coincidence_; but where a ridge and a furrow unite we have what is called _interference_. it is quite possible to send two systems of waves into the same channel, and to hold back one system a little, so that its ridges shall coincide with the furrows of the other system. the "interference" would be here complete, and the waves thus circumstanced would mutually destroy each other, smooth water being the result. in this way, by the addition of motion to motion, _rest_ may be produced. [sidenote: light added to light makes darkness.] in a precisely similar manner two systems of sonorous waves can be caused to interfere and mutually to destroy each other: thus, by adding sound to sound, _silence_ may be produced. two beams of light also may be caused to interfere and effect their mutual extinction: thus, by adding light to light, we can produce _darkness_. here indeed we have a critical analogy between sound and light--_the_ one, in fact, which compels the most profound thinkers of the present day to assume that light, like sound, is a case of undulatory motion. we see here the vision of the intellect prolonged beyond the boundaries of sense into the region of what might be considered mere imagination. but, unlike other imaginations, we can bring ours to the test of experiment; indeed, so great a mastery have we obtained over these waves, which eye has not seen, nor ear heard, that we can with mathematical certainty cause them to coincide or to interfere, to help each other or to destroy each other, at pleasure. it is perhaps possible to be a little more precise here. let two stones--with a small distance between them--be dropped into water at the same moment; a system of circular waves will be formed round each stone. let the distance from one little crest to the next following one be called _the length of the wave_, and now let us inquire what will take place at a point equally distant from the places where the two stones were dropped in. fixing our attention upon the ridge of the first wave in each case, it is manifest that, as the water propagates both systems with the same velocity, the two foremost ridges will reach the point in question at the same moment; the ridge of one would therefore coincide with the ridge of the other, and the water at this point would be lifted to a height greater than that of either of the previous ridges. [sidenote: coincidence and interference.] again, supposing that by any means we had it in our power to retard one system of waves so as to cause the first ridge of the one to be exactly one wave length behind the first ridge of the other, when they arrive at the point referred to. it is plain that the first ridge of the retarded system now falls in with the second ridge of the unretarded system, and we have another case of coincidence. a little reflection will show the same to be true when one system is retarded any number of _whole wave-lengths_; the first ridge of the retarded system will always, at the point referred to, coincide with a _ridge_ of the unretarded system. but now suppose the one system to be retarded only _half a wave-length_; it is perfectly clear that, in this case the first ridge of the retarded system would fall in with the first _furrow_ of the unretarded system, and instead of coincidence we should have interference. one system, in fact, would tend to make a hollow at the point referred to, the other would tend to make a hill, and thus the two systems would oppose and neutralize each other, so that neither the hollow nor the hill would be produced; the water would maintain its ordinary level. what is here said of a single half-wave-length of retardation, is also true if the retardation amount to any _odd_ number of half-wave-lengths. in all such cases we should have the ridge of the one system falling in with the furrow of the other; a mutual destruction of the waves of both systems being the consequence. the same remarks apply when the point, instead of being equally distant from both stones, is an even or an odd number of semi-undulations farther from the one than from the other. in the former case we should have coincidence, and in the latter case interference, at the point in question. [sidenote: liquid waves.] to the eye of a person who understands these things, nothing can be more interesting than the rippling of water under certain circumstances. by the action of interference its surface is sometimes shivered into the most beautiful mosaic, shifting and trembling as if with a kind of visible music. when the tide advances over a sea-beach on a calm and sunny day, and its tiny ripples enter, at various points, the clear shallow pools which the preceding tide had left behind, the little wavelets run and climb and cross each other, and thus form a lovely _chasing_, which has its counterpart in the lines of light converged by the ripples upon the sand underneath. when waves are skilfully generated in a vessel of mercury, and a strong light reflected from the surface of the metal is received upon a screen, the most beautiful effects may be observed. the shape of the vessel determines, in part, the character of the figures produced; in a circular dish of mercury, for example, a disturbance at the centre propagates itself in circular waves, which after reflection again encircle the centre. if the point of disturbance be a little removed from the centre, the intersections of the direct and reflected waves produce the magnificent chasing shown in the annexed figure ( ), which i have borrowed from the excellent work on waves by the messrs. weber. the luminous figure reflected from such a surface is exceedingly beautiful. when the mercury is lightly struck by a glass point, in a direction concentric with the circumference of the vessel, the lines of light run round the vessel in mazy coils, interlacing and unravelling themselves in the most wonderful manner. if the vessel be square, a splendid mosaic is produced by the crossing of the direct and reflected waves. description, however, can give but a feeble idea of these exquisite effects;-- "thou canst not wave thy staff in the air, or dip thy paddle in the lake, but it carves the brow of beauty there, and the ripples in rhymes the oar forsake." [sidenote: chasing produced by waves.] [illustration: fig. . chasing produced by waves.] [sidenote: effect of retardation.] now, all that we have said regarding the retardation of the waves of water, by a whole undulation and a semi-undulation, is perfectly applicable to the case of light. two luminous points may be placed near to each other so as to resemble the two stones dropped into the water; and when the light of these is properly received upon a screen, or directly upon the retina, we find that at some places the action of the rays upon each other produces darkness, and at others augmented light. the former places are those where the rays emitted from one point are an _odd_ number of semi-undulations in advance of the rays sent from the other; the latter places are those where the difference of path described by the rays is either nothing, or an _even_ number of semi-undulations. supposing _a_ and _b_ (fig. ) to be two such sources of light, and s r a screen on which the light falls; at a point _l_, equally distant from _a_ and _b_, we have _light_; at a point _d_, where _a d_ is half an undulation longer than _b d_, we have darkness; at _l'_, where _a l'_ is a whole wave-length, or two semi-undulations, longer than _b l'_, we again have light; and at a point _d'_, where the difference is three semi-undulations, we have darkness; and thus we obtain a series of bright and dark spaces as we recede laterally from the central point _l_. [illustration: fig. . diagram explanatory of interference.] let a bit of tin foil be closely pasted upon a piece of glass, and the edge of a penknife drawn across the foil so as to produce a slit. looking through this slit at a small and distant light, we find the light spread out in a direction at right angles to the slit, and if the light looked at be _monochromatic_, that is, composed of a single colour, we shall have a series of bright and dark bars corresponding to the points at which the rays from the different points of the slit alternately coincide and interfere upon the retina. by properly drawing a knife across a sheet of letter-paper a suitable slit may also be obtained; and those practised in such things can obtain the effect by looking through their fingers or their eyelashes. [illustration: interference spectra, produced by diffraction. fig. . _to face_ p. .] [sidenote: chromatic effects.] but if the light looked at be white, the light of a candle for example, or of a jet of gas, instead of having a series of bright and dark bars, we have the bars _coloured_. and see how beautifully this harmonizes with what has been already said regarding the different lengths of the waves which produce different colours. looking again at fig. we see that a certain obliquity is necessary to cause one ray to be a whole undulation in advance of the other at the point _l'_; but it is perfectly manifest that the obliquity must depend upon the length of the undulation; a long undulation would require a greater obliquity than a short one; red light, for example, requires a greater obliquity than blue light; so that if the point _l'_ represents the place where the first bar of red light would be at its maximum strength, the maximum for blue would lie a little to the left of _l'_; the different colours are in this way separated from each other, and exhibit themselves as distinct fringes when a distant source of white light is regarded through a narrow slit. by varying the shape of the aperture we alter the form of the chromatic image. a circular aperture, for example, placed in front of a telescope through which a point of white light is regarded, is seen surrounded by a concentric system of coloured rings. if we multiply our slits or apertures the phenomena augment in complexity and splendour. to give some notion of this i have copied from the excellent work of m. schwerd the annexed figure (fig. ) which represents the gorgeous effect observed when a distant point of light is looked at through two gratings with slits of different widths.[b] a bird's feather represents a peculiar system of slits, and the effect observed on properly looking through it is extremely interesting. [sidenote: colours of thin films.] there are many ways by which the retardation necessary to the production of interference is effected. the splendid colours of a soap-bubble are entirely due to interference; the beam falling upon the transparent film is partially reflected at its outer surface, but a portion of it enters the film and is reflected at its _inner_ surface. the latter portion having crossed the film and returned, is retarded, in comparison with the former, and, if the film be of suitable thickness, these two beams will clash and extinguish each other, while another thickness will cause the beams to coincide and illuminate the film with a light of greater intensity. from what has been said it must be manifest that to make two red beams thus coincide a thicker film would be required than would be necessary for two blue or green beams; thus, when the thickness of the bubble is suitable for the development of red, it is not suitable for the development of green, blue, &c.; the consequence is that we have different colours at different parts of the bubble. owing to its compactness and to its being shaded by a covering of débris from the direct heat of the sun, the ice underneath the moraines of glaciers appears sometimes of a pitchy blackness. while cutting such ice with my axe i have often been surprised and delighted by sudden flashes of coloured light which broke like fire from the mass. these flashes were due to internal rupture, by which fissures were produced as thin as the film of a soap-bubble; the colours being due to the interference of the light reflected from the opposite sides of the fissures. if spirit of turpentine, or olive oil, be thrown upon water, it speedily spreads in a thin film over the surface, and the most gorgeous chromatic phenomena may be thus produced. oil of lemons is also peculiarly suited to this experiment. if water be placed in a tea-tray, and light of sufficient intensity be suffered to fall upon it, this light will be reflected from the upper and under surfaces of the film of oil, and the colours thus produced may be received upon a screen, and seen at once by many hundred persons. if the oil of cinnamon be used, fine colours are also obtained, and the breaking up of this film exhibits a most interesting case of molecular action. by using a kind of varnish, instead of oil, mr. delarue has imparted such tenacity to these films that they may be removed from the water on which they rest and preserved for any length of time. by such films the colours of certain beetles, and of the wings of certain insects, may be accurately imitated; and a rook's feather may be made to shine with magnificent iridescences. the colours of tempered metals, and the beautiful metallochrome of nobili are also due to a similar cause. [sidenote: diffraction.] these colours are called the colours of _thin plates_, and are distinguished in treatises on optics from the coloured bars and fringes above referred to, which are produced by _diffraction_, or the bending of the waves round the edge of an object. one result of this bending, which is of interest to us, was obtained by the celebrated thomas young. permitting a beam of sunlight to enter a dark room through an aperture made with a fine needle, and placing in the path of the beam a bit of card one-thirtieth of an inch wide, he found the shadow of this card, or rather the line on which its shadow might be supposed to fall, always _bright_; and he proved the effect to be due to the bending of the waves of ether round the two edges of the card, and their coincidence at the other side. it has, indeed, been shown by m. poisson, that the centre of the shadow of a small circular opaque disk which stands in the way of a beam diverging from a point is exactly as much illuminated as if the disk were absent. the singular effects described by m. necker in the letter quoted at page at once suggest themselves here; and we see how possible it is for the solar rays, in grazing a distant tree, so to bend round it as to produce upon the retina, where shadow might be expected, the impression of a tree of light.[c] another effect of diffraction is especially interesting to us at present. let the seed of lycopodium be scattered over a glass plate, or even like a cloud in the air, and let a distant point of light be regarded through it; the luminous point will appear surrounded by a series of coloured rings, and when the light is intense, like the electric or the drummond light, the effect is exceedingly fine. [sidenote: cloud iridescence, etc., explained.] and now for the application of these experiments. i have already mentioned a series of coloured rings observed around the sun by mr. huxley and myself from the rhone glacier; i have also referred to the cloud iridescences on the aletschhorn; and to the colours observed during my second ascent of monte rosa, the magnificence of which is neither to be rendered by pigments nor described in words. all these splendid phenomena are, i believe, produced by diffraction, the vesicles or spherules of water in the case of the cloud acting the part of the sporules in the case of the lycopodium. the coloured fringe which surrounds the _spirit of the brocken_, and the spectra which i have spoken of as surrounding the sun, are also produced by diffraction. by the interference of their rays in the earth's atmosphere the stars can momentarily quench themselves; and probably to an intermittent action of this kind their twinkling, and the swift chromatic changes already mentioned, are due. does not all this sound more like a fairy tale than the sober conclusions of science? what effort of the imagination could transcend the realities here presented to us? the ancients had their spheral melodies, but have not we ours, which only want a sense sufficiently refined to hear them? immensity is filled with this music; wherever a star sheds its light its notes are heard. our sun, for example, thrills concentric waves through space, and every luminous point that gems our skies is surrounded by a similar system. i have spoken of the rising, climbing and crossing of the tiny ripples of a calm tide upon a smooth strand; but what are they to those intersecting ripples of the "uncontinented deep" by which infinity is engine-turned! crossing solar and stellar distances, they bring us the light of sun and stars; thrilled back from our atmosphere, they give us the blue radiance of the sky; rounding liquid spherules, they clash at the other side, and the survivors of the tumult bear to our vision the wondrous cloud-dyes of monte rosa. footnotes: [a] the vibrations of the air of a room in which a musical instrument is sounded may be made manifest by the way in which fine sand arranges itself upon a thin stretched membrane over which it is strewn; and indeed savart has thus rendered visible the vibrations of the tympanum itself. every trace of sand was swept from a paper drum held in the clock-tower of westminster when the great bell was sounded. another way of showing the propagation of aërial pulses is to insert a small gas jet into a vertical glass tube about a foot in length, in which the flame may be caused to burn tranquilly. on pitching the voice to the note of an open tube a foot long, the little flame quivers, stretches itself, and responds by producing a clear melodious note of the same pitch as that which excited it. the flame will continue its song for hours without intermission. [b] i am not aware whether in his own country, or in any other, a recognition at all commensurate with the value of the performance has followed schwerd's admirable essay entitled 'the phenomena of diffraction deduced from the theory of undulation.' [c] i think, however, that the strong irradiation from the glistening sides of the twigs and branches must also contribute to the result. [sidenote: radiant heat.] ( .) thus, then, we have been led from sound to light, and light now in its turn will lead us to _radiant heat_; for in the order in which they are here mentioned the conviction arose that they are all three different kinds of motion. it has been said that the beams of the sun consist of rays of different colours, but this is not a complete statement of the case. the sun emits a multitude of rays which are perfectly non-luminous; and the same is true, in a still greater degree, of our artificial sources of illumination. measured by the quantity of heat which they produce, per cent. of the rays emanating from a flame of oil are obscure; while out of every of those which emanate from an alcohol flame are of the same description.[a] [sidenote: obscure rays.] in fact, the visible solar spectrum simply embraces an interval of rays of which the eye is formed to take cognizance, but it by no means marks the limits of solar action. beyond the violet end of the spectrum we have obscure rays capable of producing chemical changes, and beyond the red we have rays possessing a high heating power, but incapable of exciting the impression of light. this latter fact was first established by sir william herschel, and it has been amply corroborated since. the belief now universally prevalent is, that the rays of heat differ from the rays of light simply as one colour differs from another. as the waves which produce red are longer than those which produce yellow, so the waves which produce this obscure heat are longer than those which produce red. in fact, it may be shown that the longest waves never reach the retina at all; they are completely absorbed by the humours of the eye. what is true of the sun's obscure rays is also true of calorific rays emanating from any obscure source,--from our own bodies, for example, or from the surface of a vessel containing boiling water. we must, in fact, figure a warm body also as having its particles in a state of vibration. when these motions are communicated from particle to particle of the body the heat is said to be _conducted_; when, on the contrary, the particles transmit their vibrations through the surrounding ether, the heat is said to be _radiant_. this radiant heat, though obscure, exhibits a deportment exactly similar to light. it may be refracted and reflected, and collected in the focus of a mirror or of a suitable lens. the principle of interference also applies to it, so that by adding heat to heat we can produce _cold_. the identity indeed is complete throughout, and, recurring to the analogy of sound, we might define this radiant heat to be light of too low a pitch to be visible. i have thus far spoken of _obscure_ heat only; but the selfsame ray may excite both light and heat. the red rays of the spectrum possess a very high heating power. it was once supposed that the heat of the spectrum was an essence totally distinct from its light; but a profounder knowledge dispels this supposition, and leads us to infer that the selfsame ray, falling upon the nerves of feeling, excites heat, and falling upon the nerves of seeing, excites light. as the same electric current, if sent round a magnetic needle, along a wire, and across a conducting liquid, produces different physical effects, so also the same agent acting upon different organs of the body affects our consciousness differently. footnotes: [a] melloni. ( .) [sidenote: heat a kind of motion.] heat has been defined in the foregoing section as a motion of the molecules or atoms of a body; but though the evidence in favour of this view is at present overwhelming, i do not ask the reader to accept it as a certainty, if he feels sceptically disposed. in this case, i would only ask him to accept it as a symbol. regarded as a mere physical image, a kind of paper-currency of the mind, convertible, in due time, into the gold of truth, the hypothesis will be found exceedingly useful. all known bodies possess more or less of this molecular motion, and all bodies are communicating it to the ether in which they are immersed. ice possesses it. ice before it melts attains a temperature of ° fahr., but the substance in winter often possesses a temperature far below °, so that in rising to ° it is _warmed_. in experimenting with ice i have often had occasion to cool it to ° and more below the freezing point, and to warm it afterwards up to °. if then we stand before a wall of ice, the wall radiates heat to us, and we also radiate heat to it; but the quantity which we radiate being greater than that which the ice radiates, we lose more than we gain, and are consequently chilled. if, on the contrary, we stand before a warm stove, a system of exchanges also takes place; but here the quantity we receive is in excess of the quantity lost, and we are warmed by the difference. in like manner the earth radiates heat by day and by night into space, and against the sun, moon, and stars. by day, however, the quantity received is greater than the quantity lost, and the earth is warmed; by night the conditions are reversed; the earth radiates more heat than is sent to her by the moon and stars, and she is consequently cooled. but here an important point is to be noted:--the earth receives the heat of the sun, moon, and stars, in great part as _luminous_ heat, but she gives it out as _obscure_ heat. i do not now speak of the heat reflected by the earth into space, as the light of the moon is to us; but of the heat which, after it has been absorbed by the earth, and has contributed to warm it, is radiated into space, as if the earth itself were its independent source. thus we may properly say that the heat radiated from the earth is _different in quality_ from that which the earth has received from the sun. [sidenote: qualities of heat.] in one particular especially does this difference of quality show itself; besides being non-luminous, the heat radiated from the earth is more easily intercepted and absorbed by almost all transparent substances. a vast portion of the sun's rays, for example, can pass instantaneously through a thick sheet of water; gunpowder could easily be fired by the heat of the sun's rays converged by passing through a thick water lens; the drops upon leaves in greenhouses often act as lenses, and cause the sun to burn the leaves upon which they rest. but with regard to the rays of heat emanating from an obscure source, they are all absorbed by a layer of water less than the th of an inch in thickness: water is opaque to such rays, and cuts them off almost as effectually as a metallic screen. the same is true of other liquids, and also of many transparent solids. [sidenote: the atmosphere like a ratchet.] assuming the same to be true of gaseous bodies, that they also intercept the obscure rays much more readily than the luminous ones, it would follow that while the sun's rays penetrate our atmosphere with freedom, the change which they undergo in warming the earth deprives them in a measure of this penetrating power. they can reach the earth, but _they cannot get back_; thus the atmosphere acts the part of a ratchet-wheel in mechanics; it allows of motion in one direction, but prevents it in the other. de saussure, fourier, m. pouillet, and mr. hopkins have developed this speculation, and drawn from it consequences of the utmost importance; but it nevertheless rested upon a basis of conjecture. indeed some of the eminent men above-named deemed its truth beyond the possibility of experimental verification. melloni showed that for a distance of or feet the absorption of obscure rays by the atmosphere was absolutely inappreciable. hence, the _total_ absorption being so small as to elude even melloni's delicate tests, it was reasonable to infer that _differences_ of absorption, if such existed at all, must be far beyond the reach of the finest means which we could apply to detect them. [sidenote: differences of absorption by gases.] this exclusion of one of the three states of material aggregation from the region of experiment was, however, by no means satisfactory; for our right to infer, from the deportment of a solid or a liquid towards radiant heat, the deportment of a gas, is by no means evident. in both liquids and solids we have the molecules closely packed, and more or less chained by the force of cohesion; in gases, on the contrary, they are perfectly free, and widely separated. how do we know that the interception of radiant heat by liquids and solids may not be due to an arrangement and comparative rigidity of their parts, which gases do not at all share? the assumption which took no note of such a possibility seemed very insecure, and called for verification. my interest in this question was augmented by the fact, that the assumption referred to lies, as will be seen, at the root of the glacier question. i therefore endeavoured to fill the gap, and to do for gases and vapours what had been already so ably done for liquids and solids by melloni. i tried the methods heretofore pursued, and found them unavailing; oxygen, hydrogen, nitrogen, and atmospheric air, examined by such methods, showed no action upon radiant heat. nature was dumb, but the question occurred, "had she been addressed in the proper language?" if the experimentalist is convinced of this, he will rest content even with a negative; but the absence of this conviction is always a source of discomfort, and a stimulus to try again. the principle of the method finally applied is all that can here be referred to; and it, i hope, will be quite intelligible. two beams of heat, from two distinct sources, were allowed to fall upon the same instrument,[a] and to contend there for mastery. when both beams were perfectly equal, they completely neutralized each other's action; but when one of them was in any sensible degree stronger than the other, the predominance of the former was shown by the instrument. it was so arranged that one of the conflicting beams passed through a tube which could be exhausted of air, or filled with any gas; thus varying at pleasure the medium through which it passed. the question then was, supposing the two beams to be equal when the tube was filled with air, will the exhausting of the tube disturb the equality? the answer was affirmative; the instrument at once showed that a greater quantity of heat passed through the vacuum than through the air. the experiment was so arranged that the effect thus produced was very large as measured by the indications of the instrument. but the action of the simple gases, oxygen, hydrogen, and nitrogen, was incomparably less than that produced by some of the compound gases, while these latter again differed widely from each other. vapours exhibited differences of equal magnitude. the experiments indeed proved that gaseous bodies varied among themselves, as to their power of transmitting radiant heat, just as much as liquids and solids. it was in the highest degree interesting to observe how a gas or vapour of perfect transparency, as regards light, acted like an opaque screen upon the heat. to the eye, the gas within the tube might be as invisible as the air itself, while to the radiant heat it behaved like a cloud which it was almost impossible to penetrate. [sidenote: selected heat.] applying the same method, i have found that from the sun, from the electric light, or from the lime-light, a large amount of heat can be selected, which is unaffected not only by air, but by the most energetic gases that experiment has revealed to me; while this same heat, when it has its _quality_ changed by being rendered obscure, is powerfully intercepted. thus the bold and beautiful speculation above referred to has been made an experimental fact; the radiant heat of the sun does certainly pass through the atmosphere to the earth with greater facility than the radiant heat of the earth can escape into space. [sidenote: possible heat of neptune.] it is probable that, were the earth unfurnished with this atmospheric swathing, its conditions of temperature would be such as to render it uninhabitable by man; and it is also probable that a suitable atmosphere enveloping the most distant planet might render it, as regards temperature, perfectly habitable. if the planet neptune, for example, be surrounded by an atmosphere which permits the solar and stellar rays to pass towards the planet, but cuts off the escape of the warmth which they excite, it is easy to see that such an accumulation of heat may at length take place as to render the planet a comfortable habitation for beings constituted like ourselves.[b] but let us not wander too far from our own concerns. where radiant heat is allowed to fall upon an absorbing substance, a certain thickness of the latter is always necessary for the absorption. supposing we place a thin film of glass before a source of heat, a certain percentage of the heat will pass through the glass, and the remainder will be absorbed. let the transmitted portion fall upon a second film similar to the first, a smaller percentage than before will be absorbed. a third plate would absorb still less, a fourth still less; and, after having passed through a sufficient number of layers, the heat would be so _sifted_ that all the rays capable of being absorbed by glass would be abstracted from it. suppose all these films to be placed together so as to form a single thick plate of glass, it is evident that the plate must act upon the heat which falls upon it, in such a manner that the major portion is absorbed _near the surface at which the heat enters_. this has been completely verified by experiment. [sidenote: cold of upper atmosphere.] applying this to the heat radiated from the earth, it is manifest that the greatest quantity of this heat will be absorbed by the lowest atmospheric strata. and here we find ourselves brought, by considerations apparently remote, face to face with the fact upon which the existence of all glaciers depends, namely, the comparative coldness of the upper regions of the atmosphere. the sun's rays can pass in a great measure through these regions without heating them; and the earth's rays, which they might absorb, hardly reach them at all, but are intercepted by the lower portions of the atmosphere.[c] another cause of the greater coldness of the higher atmosphere is the expansion of the denser air of the lower strata when it ascends. the dense air makes room for itself by pushing back the lighter and less elastic air which surrounds it: _it does work_, and, to perform this work, a certain amount of heat must be consumed. it is the consumption of this heat--its absolute annihilation as heat--that chills the expanded air, and to this action a share of the coldness of the higher atmosphere must undoubtedly be ascribed. a third cause of the difference of temperature is the large amount of heat communicated, _by way of contact_, to the air of the earth's surface; and a fourth and final cause is the loss endured by the highest strata through radiation into space. footnotes: [a] the opposite faces of a thermo-electric pile. [b] see a most interesting paper on this subject by mr. hopkins in the cambridge 'transactions,' may, . [c] see m. pouillet's important memoir on solar radiation. taylor's scientific memoirs, vol. iv. p. . origin of glaciers. ( .) [sidenote: the snow-line.] having thus accounted for the greater cold of the higher atmospheric regions, its consequences are next to be considered. one of these is, that clouds formed in the lower portions of the atmosphere, in warm and temperate latitudes, usually discharge themselves upon the earth as rain; while those formed in the higher regions discharge themselves upon the mountains as snow. the snow of the higher atmosphere is often melted to rain in passing through the warmer lower strata: nothing indeed is more common than to pass, in descending a mountain, from snow to rain; and i have already referred to a case of this kind. the appearance of the grassy and pine-clad alps, as seen from the valleys after a wet night, is often strikingly beautiful; the level at which the snow turned to rain being distinctly marked upon the slopes. above this level the mountains are white, while below it they are green. the eye follows this _snow-line_ with ease along the mountains, and when a sufficient extent of country is commanded its regularity is surprising. the term "snow-line," however, which has been here applied to a local and temporary phenomenon, is commonly understood to mean something else. in the case just referred to it marked the place where the supply of solid matter from the upper atmospheric regions, during a single fall, was exactly equal to its consumption; but the term is usually understood to mean the line along which the quantity of snow which falls _annually_ is melted, and no more. below this line each year's snow is completely cleared away by the summer heat; above it a residual layer abides, which gradually augments in thickness from the snow-line upwards. [sidenote: mountains unloaded by glaciers.] here then we have a fresh layer laid on every year; and it is evident that, if this process continued without interruption, every mountain which rises above the snow-line must augment annually in height; the waters of the sea thus piled, in a solid form, upon the summits of the hills, would raise the latter to an indefinite elevation. but, as might be expected, the snow upon steep mountain-sides frequently slips and rolls down in avalanches into warmer regions, where it is reduced to water. a comparatively small quantity of the snow is, however, thus got rid of, and the great agent which nature employs to relieve her overladen mountains is the glaciers. let us here avoid an error which may readily arise out of the foregoing reflections. the principal region of clouds and rain and snow extends only to a limited distance upwards in the atmosphere; the highest regions contain very little moisture, and were our mountains sufficiently lofty to penetrate those regions, the quantity of snow falling upon their summits would be too trifling to resist the direct action of the solar rays. these would annually clear the summits to a certain level, and hence, were our mountains high enough, we should have a superior, as well as an inferior, snow-line; the region of perpetual snow would form a belt, below which, in summer, snowless valleys and plains would extend, and above which snowless summits would rise. ( .) [sidenote: white and blue ice.] at its origin then a glacier is snow--at its lower extremity it is ice. the blue blocks that arch the source of the arveiron were once powdery snow upon the slopes of the col du géant. could our vision penetrate into the body of the glacier, we should find that the change from white to blue essentially consists in the gradual expulsion of the air which was originally entangled in the meshes of the fallen snow. whiteness always results from the intimate and irregular mixture of air and a transparent solid; a crushed diamond would resemble snow; if we pound the most transparent rock-salt into powder we have a substance as white as the whitest culinary salt; and the colourless glass vessel which holds the salt would also, if pounded, give a powder as white as the salt itself. it is a law of light that in passing from one substance to another possessing a different power of refraction, a portion of it is always reflected. hence when light falls upon a transparent solid mixed with air, at each passage of the light from the air to the solid and from the solid to the air a portion of it is reflected; and, in the case of a powder, this reflection occurs so frequently that the passage of the light is practically cut off. thus, from the mixture of two perfectly transparent substances, we obtain an opaque one; from the intimate mixture of air and water we obtain foam; clouds owe their opacity to the same principle; and the condensed steam of a locomotive casts a shadow upon the fields adjacent to the line, because the sunlight is wasted in echoes at the innumerable limiting surfaces of water and air. [sidenote: air-bubbles in ice.] the snow which falls upon high mountain-eminences has often a temperature far below the freezing point of water. such snow is _dry_, and if it always continued so the formation of a glacier from it would be impossible. the first action of the summer's sun is to raise the temperature of the superficial snow to °, and afterwards to melt it. the water thus formed percolates through the colder mass underneath, and this i take to be the first active agency in expelling the air entangled in the snow. but as the liquid trickles over the surfaces of granules colder than itself it is partially deposited in a solid form on these surfaces, thus augmenting the size of the granules, and cementing them together. when the mass thus formed is examined, the air within it is found as _round bubbles_. now it is manifest that the air caught in the irregular interstices of the snow can have no tendency to assume this form so long as the snow remains solid; but the process to which i have referred--the saturation of the lower portions of the snow by the water produced by the melting of the superficial portions--enables the air to form itself into globules, and to give the ice of the _névé_ its peculiar character. thus we see that, though the sun cannot get directly at the deeper portions of the snow, by liquefying the upper layer he charges it with heat, and makes it his messenger to the cold subjacent mass. the frost of the succeeding winter may, i think, or may not, according to circumstances, penetrate through this layer, and solidify the water which it still retains in its interstices. if the winter set in with clear frosty weather, the penetration will probably take place; but if heavy snow occur at the commencement of winter, thus throwing a protective covering over the _névé_, freezing to any great depth may be prevented. mr. huxley's idea seems to be quite within the range of possibility, that water-cells may be transmitted from the origin of the glacier to its end, retaining their contents always liquid. [sidenote: snow pressed to ice.] it was formerly supposed, and is perhaps still supposed by many, that the snow of the mountains is converted into the ice of the glacier by the process of saturation and freezing just indicated. but the frozen layer would not yet resemble glacier ice; it is only at the deeper portions of the _névé_ that we find an approximation to the true ice of the glacier. this brings us to the second great agent in the process of glacification, namely, pressure. the ice of the _névé_ at ° may be squeezed or crushed with extreme facility; and if the force be applied slowly and with caution, the yielding of the mass may be made to resemble the yielding of a plastic body. in the depths of the _névé_, where each portion of the ice is surrounded by a resistant mass, rude crushing is of course out of the question. the layers underneath yield with extreme slowness to the pressure of the mass above them; they are squeezed, but not rudely fractured; and even should rude fracture occur, the ice, as shall subsequently be shown, possesses the power of restoring its own continuity. thus, then, the lower portions of the _névé_ are removed by pressure more and more from the condition of snow, the air-bubbles which give to the _névé_-ice its whiteness are more and more expelled, and this process, continued throughout the entire glacier, finally brings the ice to that state of magnificent transparency which we find at the termination of the glacier of rosenlaui and elsewhere. this is all capable of experimental proof. the messrs. schlagintweit compressed the snow of the _névé_ to compact ice; and i have myself frequently obtained slabs of ice from snow in london. colour of water and ice. ( .) the sun is continually sending forth waves of different lengths, all of which travel with the same velocity through the ether. when these waves enter a prism of glass they are retarded, but in different degrees. the shorter waves suffer the greatest retardation, and in consequence of this are most deflected from their straight course. it is this property which enables us to separate one from the other in the solar spectrum, and this separation proves that the waves are by no means inextricably entangled with each other, but that they travel independently through space. in consequence of this independence, the same body may intercept one system of waves while it allows another to pass: on this quality, indeed, depend all the phenomena of colour. a red glass, for example, is red because it is so constituted that it destroys the shorter waves which produce the other colours, and transmits only the waves which produce red. i may remark, however, that scarcely any glass is of a pure colour; along with the predominant waves, some of the other waves are permitted to pass. the colours of flowers are also very impure; in fact, to get pure colours we must resort to a delicate prismatic analysis of white light. [sidenote: long waves most absorbed.] it has already been stated that a layer of water less than the twentieth of an inch in thickness suffices to stop and destroy all waves of radiant heat emanating from an obscure source. the longer waves of the obscure heat cannot get through water, and i find that all transparent compounds which contain _hydrogen_ are peculiarly hostile to the longer undulations. it is, i think, the presence of this element in the humours of the eye which prevents the extra red rays of the solar spectrum from reaching the retina. it is interesting to observe that while bisulphide of carbon, chloride of phosphorus, and other liquids which contain no hydrogen, permit a large portion of the rays emanating from an iron or copper ball, at a heat below redness, to pass through them with facility, the same thickness of substances equally transparent, but which contain hydrogen, such as ether, alcohol, water, or the vitreous humour of the eye of an ox, completely intercepts these obscure rays. the same is true of solid bodies; a very slight thickness of those which contain hydrogen offers an impassable barrier to all rays emanating from a non-luminous source.[a] but the heat thus intercepted is by no means lost; its _radiant form_ merely is destroyed. its waves are shivered upon the particles of the body, but they impart warmth to it, while the heat which retains its radiant form contributes in no way to the warmth of the body through which it passes. [sidenote: final colour of ice and water blue.] water then absorbs all the extra red rays of the sun, and if the layer be thick enough it invades the red rays themselves. thus the greater the distance the solar beams travel through pure water the more are they deprived of those components which lie at the red end of the spectrum. the consequence is, that the light finally transmitted by the water, and which gives to it its colour, is _blue_. [sidenote: experiment.] i find the following mode of examining the colour of water both satisfactory and convenient:--a tin tube, fifteen feet long and three inches in diameter, has its two ends stopped securely by pieces of colourless plate glass. it is placed in a horizontal position, and pure water is poured into it through a small lateral pipe, until the liquid reaches half way up the glasses at the ends; the tube then holds a semi-cylinder of water and a semi-cylinder of air. a white plate, or a sheet of white paper, well illuminated, is then placed at a little distance from one end of the tube, and is looked at through the tube. two semicircular spaces are then seen, one by the light which has passed through the air, the other by the light which has passed through the water; and their proximity furnishes a means of comparison, which is absolutely necessary in experiments of this kind. it is always found that, while the former semicircle remains white, the latter one is vividly coloured.[b] when the beam from an electric lamp is sent through this tube, and a convex lens is placed at a suitable distance from its most distant end, a magnified image of the coloured and uncoloured semicircles may be projected upon a screen. tested thus, i have sometimes found, after rain, the ordinary pipe-water of the royal institution quite opaque; while, under other circumstances, i have found the water of a clear green. the pump-water of the institution thus examined exhibits a rich sherry colour, while distilled water is blue-green. the blueness of the grotto of capri is due to the fact that the light which enters it has previously traversed a great depth of clear water. according to bunsen's account, the _laugs_, or cisterns of hot water, in iceland must be extremely beautiful. the water contains silica in solution, which, as the walls of the cistern arose, was deposited upon them in fantastic incrustations. these, though white, when looked at through the water appear of a lovely blue, which deepens in tint as the vision plunges deeper into the liquid. [sidenote: ice opaque to radiant heat.] ice is a crystal formed from this blue liquid, the colour of which it retains. ice is the most opaque of transparent solids to radiant heat, as water is the most opaque of liquids. according to melloni, a plate of ice one twenty-fifth of an inch thick, which permits the rays of light to pass without sensible absorption, cuts off per cent. of the rays of heat issuing from a powerful oil lamp, - / per cent. of the rays issuing from incandescent platinum, and the whole of the rays issuing from an obscure source. the above numbers indicate how large a portion of the rays emitted by our artificial sources of light is obscure. when the rays of light pass through a sufficient thickness of ice the longer waves are, as in the case of water, more and more absorbed, and the final colour of the substance is therefore blue. but when the ice is filled with minute air-bubbles, though we should loosely call it _white_, it may exhibit, even in small pieces, a delicate blue tint. this, i think, is due to the frequent interior reflection which takes place at the surfaces of the air-cells; so that the light which reaches the eye from the interior may, in consequence of its having been reflected hither and thither, really have passed through a considerable thickness of ice. the same remark, as we have already seen, applies to the delicate colour of newly fallen snow. footnotes: [a] what is here stated regarding hydrogen is true of all the liquids and solids which have hitherto been examined,--but whether any exceptions occur, future experience must determine. it is only when in combination that it exhibits this impermeability to the obscure rays. [b] in my own experiments i have never yet been able to obtain a pure blue, the nearest approach to it being a blue-green. colours of the sky. ( .) [sidenote: newton's hypothesis.] in treating of the colours of thin plates we found that a certain thickness was necessary to produce blue, while a greater thickness was necessary for red. with that wonderful power of generalization which belonged to him, newton thus applies this apparently remote fact to the blue of the sky:--"the blue of the first order, though very faint and little, may possibly be the colour of some substances, and particularly the azure colour of the skies seems to be of this order. for all vapours, when they begin to condense and coalesce into small parcels, become first of that bigness whereby such an azure is reflected, before they can constitute clouds of other colours. and so, this being the first colour which vapours begin to reflect, it ought to be the colour of the finest and most transparent skies, in which vapours are not arrived at that grossness requisite to reflect other colours, as we find it is by experience." m. clausius has written a most interesting paper, which he endeavours to show that the minute particles of water which are supposed by newton to reflect the light, cannot be little globes entirely composed of water, but bladders or hollow spheres; the vapour must be in what is generally termed the _vesicular_ state. he was followed by m. brücke, whose experiments prove that the suspended particles may be so small that the reasoning of m. clausius may not apply to them. but why need we assume the existence of such particles at all?--why not assume that the colour of the air is blue, and renders the light of the sun blue, after the fashion of a blue glass or a solution of the sulphate of copper? i have already referred to the great variation which the colour of the firmament undergoes in the alps, and have remarked that this seems to indicate that the blue depends upon some variable constituent of the atmosphere. further, we find that the blue light of the sky is _reflected_ light; and there must be something in the atmosphere capable of producing this reflection; but this thing, whatever it is, produces another effect which the blue glass or liquid is unable to produce. these _transmit_ blue light, whereas, when the solar beams have traversed a great length of air, as in the morning or the evening, they are yellow, or orange, or even blood-red, according to the state of the atmosphere:--the transmitted light and the reflected light of the atmosphere are then totally different in colour. [sidenote: goethe's hypothesis.] goethe, in his celebrated 'farbenlehre,' gives a theory of the colour of the sky, and has illustrated it by a series of striking facts. he assumed two principles in the universe--light and darkness--and an intermediate stage of turbidity. when the darkness is seen through a turbid medium on which the light falls, the medium appears blue; when the light itself is viewed through such a medium, it is yellow, or orange, or ruby-red. this he applies to the atmosphere, which sends us blue light, or red, according as the darkness of infinite space, or the bright surface of the sun, is regarded through it. as a theory of colours goethe's work is of no value, but the facts which he has brought forward in illustration of the action of turbid media are in the highest degree interesting. he refers to the blueness of distant mountains, of smoke, of the lower part of the flame of a candle (which if looked at with a white surface behind it completely disappears), of soapy water, and of the precipitates of various resins in water. one of his anecdotes in connexion with this subject is extremely curious and instructive. the portrait of a very dignified theologian having suffered from dirt, it was given to a painter to be cleaned. the clergyman was drawn in a dress of black velvet, over which the painter, in the first place, passed his sponge. to his astonishment the black velvet changed to the colour of blue plush, and completely altered the aspect of its wearer. goethe was informed of the fact; the experiment was repeated in his presence, and he at once solved it by reference to his theory. the varnish of the picture when mixed with the water formed a turbid medium, and the black coat seen through it appeared blue; when the water evaporated the coat resumed its original aspect. [sidenote: suspended particles.] with regard to the real explanation of these effects, it may be shown, that, if a beam of white light be sent through a liquid which contains extremely minute particles in a state of suspension, the short waves are more copiously reflected by such particles than the long ones; blue, for example, is more copiously reflected than red. this may be shown by various fine precipitates, but the best is that of brücke. we know that mastic and various resins are soluble in alcohol, and are precipitated when the solution is poured into water: _eau de cologne_, for example, produces a white precipitate when poured into water. if however this precipitate be sufficiently diluted, it gives the liquid a bluish colour by reflected light. even when the precipitate is very thick and gross, and floats upon the liquid like a kind of curd, its under portions often exhibit a fine blue. to obtain particles of a proper size, brücke recommends gramme of colourless mastic to be dissolved in grammes of alcohol, and dropped into a beaker of water, which is kept in a state of agitation. in this way a blue resembling that of the firmament may be produced. it is best seen when a black cloth is placed behind the glass; but in certain positions this blue liquid appears yellow; and these are the positions when the _transmitted_ light reaches the eye. it is evident that this change of colour must necessarily exist; for the blue being partially withdrawn by more copious reflection, the transmitted light must partake more or less of the character of the complementary colour; though it does not follow that they should be exactly complementary to each other. [sidenote: the sun through london smoke.] when a long tube is filled with clear water, the colour of the liquid, as before stated, shows itself by transmitted light. the effect is very interesting when a solution of mastic is permitted to drop into such a tube, and the fine precipitate to diffuse itself in the water. the blue-green of the liquid is first neutralized, and a yellow colour shows itself; on adding more of the solution the colour passes from yellow to orange, and from orange to blood-red. with a cell an inch and a half in width, containing water, into which the solution of mastic is suffered to drop, the same effect may be obtained. if the light of an electric lamp be caused to form a clear sunlike disk upon a white screen, the gradual change of this light by augmented precipitation into deep glowing red, resembling the colour of the sun when seen through fine london smoke, is exceedingly striking. indeed the smoke acts, in some measure, the part of our finely-suspended matter. [sidenote: morning and evening red.] by such means it is possible to imitate the phenomena of the firmament; we can produce its pure blue, and cause it to vary as in nature. the milkiness which steals over the heavens, and enables us to distinguish one cloudless day from another, can be produced with the greatest ease. the yellow, orange, and red light of the morning and evening can also be obtained: indeed the effects are so strikingly alike as to suggest a common origin--that the colours of the sky are due to minute particles diffused through the atmosphere. these particles are doubtless the condensed vapour of water, and its variation in quality and amount enables us to understand the variability of the firmamental blue, and of the morning and the evening red. professor forbes, moreover, has made the interesting observation that the steam of a locomotive, at a certain stage of its condensation, is blue or red according as it is viewed by reflected or transmitted light. these considerations enable us to account for a number of facts of common occurrence. thin milk, when poured upon a black surface, appears bluish. the milk is colourless; that is, its blueness is not due to _absorption_, but to a _separation_ of the light by the particles suspended in the liquid. the juices of various plants owe their blueness to the same cause; but perhaps the most curious illustration is that presented by a blue eye. here we have no true colouring matter, no proper absorption; but we look through a muddy medium at the black choroid coat within the eye, and the medium appears blue.[a] [sidenote: colour of swiss lakes.] is it not probable that this action of finely-divided matter may have some influence on the colour of some of the swiss lakes--as that of geneva for example? this lake is simply an expansion of the river rhone, which rushes from the end of the rhone glacier, as the arveiron does from the end of the mer de glace. numerous other streams join the rhone right and left during its downward course; and these feeders, being almost wholly derived from glaciers, join the rhone charged with the finer matter which these in their motion have ground from the rocks over which they have passed. but the glaciers must grind the mass beneath them to particles of all sizes, and i cannot help thinking that the finest of them must remain suspended in the lake throughout its entire length. faraday has shown that a precipitate of gold may require months to sink to the bottom of a bottle not more than five inches high, and in all probability it would require _ages_ of calm subsidence to bring _all_ the particles which the lake of geneva contains to its bottom. it seems certainly worthy of examination whether such particles suspended in the water contribute to the production of that magnificent blue which has excited the admiration of all who have seen it under favourable circumstances. footnotes: [a] helmholtz, 'das sehen des menschen.' the moraines. ( .) the surface of the glacier does not long retain the shining whiteness of the snow from which it is derived. it is flanked by mountains which are washed by rain, dislocated by frost, riven by lightning, traversed by avalanches, and swept by storms. the lighter débris is scattered by the winds far and wide over the glacier, sullying the purity of its surface. loose shingle rattles at intervals down the sides of the mountains, and falls upon the ice where it touches the rocks. large rocks are continually let loose, which come jumping from ledge to ledge, the cohesion of some being proof against the shocks which they experience; while others, when they hit the rocks, burst like bomb-shells, and shower their fragments upon the ice. [sidenote: lateral moraines.] thus the glacier is incessantly loaded along its borders with the ruins of the mountains which limit it; and it is evident that the quantity of rock and rubbish thus cast upon the glacier depends upon the character of the adjacent mountains. where the summits are bare and friable, we may expect copious showers; where they are resistant, and particularly where they are protected by a covering of ice and snow, the quantity will be small. as the glacier moves downward, it carries with it the load deposited upon it. long ridges of débris thus flank the glacier, and these ridges are called _lateral moraines_. where two tributary glaciers join to form a trunk-glacier, their adjacent lateral moraines are laid side by side at the place of confluence, thus constituting a ridge which runs along the middle of the trunk-glacier, and which is called a _medial moraine_. the rocks and débris carried down by the glacier are finally deposited at its lower extremity, forming there a _terminal moraine_. [sidenote: medial and terminal moraines.] it need hardly be stated that the number of medial moraines is only limited by the number of branch glaciers. if a glacier have but two branches, it will have only one medial moraine; if it have three branches, it will have two medial moraines; if _n_ branches, it will have _n_- medial moraines. the number of medial moraines, in short, is always _one less_ than the number of branches. a glance at the annexed figure will reveal the manner in which the lateral moraines of the mer de glace unite to form medial ones. (see fig. .) [illustration: moraines of the mer de glace. fig. . _to face p. _.] when a glacier diminishes in size it leaves its lateral moraines stranded on the flanks of the valleys. successive shrinkings may thus occur, and _have_ occurred at intervals of centuries; and a succession of old lateral moraines, such as many glacier-valleys exhibit, is the consequence. the mer de glace, for example, has its old lateral moraines, which run parallel with its present ones. the glacier may also diminish _in length_ at distant intervals; the result being a succession of more or less concentric terminal moraines. in front of the rhone-glacier we have six or seven such moraines, and the mer de glace also possesses a series of them. let us now consider the effect produced by a block of stone upon the surface of a glacier. the ice around it receives the direct rays of the sun, and is acted on by the warm air; it is therefore constantly melting. the stone also receives the solar beams, is warmed, and transmits its heat, by conduction, to the ice beneath it. if the heat thus transmitted to the ice through the stone be less than an equal space of the surrounding ice receives, it is manifest that the ice around the stone will waste more quickly than that beneath it, and the consequence is, that, as the surface sinks, it leaves behind it a pillar of ice, on which the block is elevated. if the stone be wide and flat, it may rise to a considerable height, and in this position it constitutes what is called a glacier-_table_. (see fig. .) [sidenote: glacier tables accounted for.] almost all glaciers present examples of such tables; but no glacier with which i am acquainted exhibits them in greater number and perfection than the unteraar glacier, near the grimsel. vast masses of granite are thus poised aloft on icy pedestals; but a limit is placed to their exaltation by the following circumstance. the sun plays obliquely upon the table all day; its southern extremity receives more heat than its northern, and the consequence is, that it _dips_ towards the south. strictly speaking, the plane of the dip rotates a little during the day, being a little inclined towards the east in the morning, north and south a little after noon, and inclined towards the west in the evening; so that, theoretically speaking, the block is a sun-dial, showing by its position the hour of the day. this rotation is, however, too small to be sensible, and hence _the dip of the stones upon a glacier sufficiently exposed to the sunlight, enables us at any time to draw the meridian line along its surface_. the inclination finally becomes so great that the block slips off its pedestal, and begins to form another, while the one which it originally occupied speedily disappears, under the influence of sun and air. fig. represents a typical section of a glacier-table, the sun's rays being supposed to fall in the direction of the shading lines. [sidenote: type "table."] [illustration: fig. . typical section of a glacier table.] stones of a certain size are always lifted in the way described. a considerable portion of the heat which a large block receives is wasted by radiation, and by communication to the air, so that the quantity which reaches the ice beneath is trifling. such a mass is, of course, a protector of the ice beneath it. but if the stone be small, and dark in colour, it absorbs the heat with avidity, communicates it quickly to the ice with which it is in contact, and consequently sinks in the ice. this is also the case with bits of dirt and the finer fragments of débris; they sink in the glacier. sometimes, however, a pretty thick layer of sand is washed over the ice from the moraines, or from the mountain-sides; and such sand-layers give birth to ice-cones, which grow to peculiarly grand dimensions on the lower aar glacier. i say "grow," but the truth, of course, is, that the surrounding ice wastes, while the portion underneath the sand is so protected that it remains as an eminence behind. at first sight, these sand-covered cones appear huge heaps of dirt, but on examination they are found to be cones of ice, and that the dirt constitutes merely a superficial covering. turn we now to the moraines. protecting, as they do, the ice from waste, they rise, as might be expected, in vast ridges above the general surface of the glacier. in some cases the surrounding mass has been so wasted as to leave the spines of ice which support the moraines forty or fifty feet above the general level of the glacier. i should think the moraines of the mer de glace about the tacul rise to this height. but lower down, in the neighbourhood of the echelets, these high ridges disappear, and nought remains to mark the huge moraine but a strip of dirt, and perhaps a slight longitudinal protuberance on the surface of the glacier. how have the blocks vanished that once loaded the moraines near the tacul? they have been swallowed in the crevasses which intersect the moraines lower down; and if we could examine the ice at the echelets we should find the engulfed rocks in the body of the glacier. [sidenote: moraines engulfed and disgorged.] cases occur, wherein moraines, after having been engulfed, and hidden for a time, are again entirely disgorged by the glacier. two moraines run along the basin of the talèfre, one from the jardin, the other from an adjacent promontory, proceeding parallel to each other towards the summit of the great ice-fall. here the ice is riven, and profound chasms are formed, in which the blocks and shingle of the moraines disappear. throughout the entire ice-fall the only trace of the moraines is a broad dirt-streak, which the eye may follow along the centre of the fall, with perhaps here and there a stone which has managed to rise from its frozen sepulchre. but the ice wastes, and at the base of the fall large masses of stone begin to reappear; these become more numerous as we descend; the smaller débris also appears, and finally, at some distance below the fall, the moraine is completely restored, and begins to exercise its protecting influence; it rises upon its ridge of ice, and dominates as before over the surface of the glacier. [sidenote: transparency of ice under the moraines.] the ice under the moraines and sand-cones is of a different appearance from that of the surrounding glacier, and the principles we have laid down enable us to explain the difference. the sun's rays, striking upon the unprotected surface of the glacier, enter the ice to a considerable depth; and the consequence is, that the ice near the surface of the glacier is always disintegrated, being cut up with minute fissures and cavities, filled with water and air, which, for reasons already assigned, cause the glacier, when it is clean, to appear white and opaque. the ice under the moraines, on the contrary, is usually dark and transparent; i have sometimes seen it as black as pitch, the blackness being a proof of its great transparency, which prevents the reflection of light from its interior. the ice under the moraines cannot be assailed in its depths by the solar heat, because this heat becomes _obscure_ before it reaches the ice, and as such it lacks the power of penetrating the substance. it is also communicated in great part by way of contact instead of by radiation. a thin film at the surface of the moraine-ice engages all the heat that acts upon it, its deeper portions remaining intact and transparent. glacier motion. preliminary. ( .) [sidenote: nÉvÉ and glacier.] though a glacier is really composed of two portions, one above and the other below the snow-line, the term glacier is usually restricted to the latter, while the french term _névé_ is applied to the former. it is manifest that the snow which falls upon the glacier proper can contribute nothing to its growth or permanence; for every summer is not only competent to abolish the accumulations of the foregoing winter, but to do a great deal more. during each summer indeed a considerable quantity of the ice below the snow-line is reduced to water; so that, if the waste were not in some way supplied, it is manifest that in a few years the lower portion of the glacier must entirely disappear. the end of the mer de glace, for example, could never year after year thrust itself into the valley of chamouni, were there not some agency by which its manifest waste is made good. this agency is the motion of the glacier. to those unacquainted with the fact of their motion, but who have stood upon these vast accumulations of ice, and noticed their apparent fixity and rigidity, the assertion that a glacier moves must appear in the highest degree startling and incredible. they would naturally share the doubts of a certain professor of tübingen, who, after a visit to the glaciers of switzerland, went home and wrote a book flatly denying the possibility of their motion. but reflection comes to the aid of sense, and qualifies first impressions. we ask ourselves how is the permanence of the glacier secured? how are the moraines to be accounted for? whence come the blocks which we often find at the terminus of a glacier, and which we know belong to distant mountains? the necessity of motion to produce these results becomes more and more apparent, until at length we resort to actual experiment. we take two fixed points at opposite sides of the glacier, so that a block of stone which rests upon the ice may be in the straight line which unites the points; and we soon find that the block quits the line, and is borne downwards by the glacier. we may well realize the interest of the man who first engaged in this experiment, and the pleasure which he felt on finding that the block moved; for even now, after hundreds of observations on the motion of glaciers have been made, the actual observance of this motion for the first time is always accompanied by a thrill of delight. such pleasure the direct perception of natural truth always imparts. like antæus we touch our mother, and are refreshed by the contact. [sidenote: hugi's measurements.] the fact of glacier-motion has been known for an indefinite time to the inhabitants of the mountains; but the first who made quantitative observations of the motion was hugi. he found that from to his cabin upon the glacier of the aar had moved mètres, or about yards, downwards; in it had moved mètres; and in m. agassiz found it at a distance of , mètres from its first position. this is equivalent in round numbers to an average velocity of mètres a year. in m. agassiz fixed the position of the rock known as the hôtel des neufchâtelois; and on the th of september, , he found that it had moved feet downward. between this date and september, , the rock moved feet, thus accomplishing a distance of feet in two years. but much uncertainty prevailed regarding the motion of the boulders, for they sometimes rolled upon the glacier, and hence it was resolved to use stakes of wood driven into the ice. in the month of july, , m. escher de la linth fixed a system of stakes, every two of which were separated from each other by a distance of mètres, across the great aletsch glacier. a considerable number of other stakes were fixed _along_ the glacier, the longitudinal separation being also mètres. on the th of july the stakes stood at a depth of about three feet in the ice. on the th of august he returned to the glacier. almost all the stakes had fallen, and no trace, even of the holes in which they had been sunk, remained. m. agassiz was equally unsuccessful on the glacier of the aar. it must therefore be borne in mind, that, previous to the introduction of the facile modes of measurement which we now employ, severe labour and frequent disappointment had taught observers the true conditions of success. after his defeat upon the aletsch, m. escher joined mm. agassiz and desor on the aar glacier, where, between the st of august and the th of september, they fixed in concert the positions of a series of blocks upon the ice, with the view of measuring their displacements the following year. [sidenote: agassiz's measurements.] another observation of great importance was also commenced in . warned by previous failures, m. agassiz had iron boring-rods carried up the glacier, with which he pierced the ice at six places to a depth of ten feet, and at each place drove a wooden pile into the ice. these six stations were in the same straight line across the glacier; three of them standing upon the finsteraar and three on the lauteraar tributary. about this time also m. agassiz conceived the idea of having the displacements measured the year following with precise instruments, and also of having constructed, by a professional engineer, a map of the entire glacier, on which all its visible "accidents" should be drawn according to scale. this excellent work was afterwards executed by m. wild, now professor of geodesy and topography in the polytechnic school of zürich, and it is published as a separate atlas in connexion with m. agassiz's 'système glaciaire.' [sidenote: prof. j. d. forbes invited.] m. agassiz is a naturalist, and he appears to have devoted but little attention to the study of physics. at all events, the physical portions of his writings appear to me to be very often defective. it was probably his own consciousness of this deficiency that led him to invoke the advice of arago and others previous to setting out upon his excursions. it was also his desire "to see a philosopher so justly celebrated occupy himself with the subject," which induced him to invite prof. j. d. forbes of edinburgh to be his guest upon the aar glacier in . on the th of august they met at the grimsel hospice, and for three weeks afterwards they were engaged together daily upon the ice, sharing at night the shelter of the same rude roof. it is in reference to this visit that prof. forbes writes thus at page of the 'travels in the alps':--"far from being ready to admit, as my sanguine companions wished me to do in , that the theory of glaciers was complete, and the cause of their motion certain, after patiently hearing all they had to say and reserving my opinion, i drew the conclusion that no theory which i had then heard of could account for the few facts admitted on all hands." in prof. forbes repaired, as early as the state of the snow permitted, to the mer de glace; he worked there, in the first instance, for a week, and afterwards crossed over to courmayeur to witness a solar eclipse. the result of his week's observations was immediately communicated to prof. jameson, then editor of the 'edinburgh new philosophical journal.' [sidenote: centre moves quickest.] in that letter he announces the fact, but gives no details of the measurement, that "the central part of the glacier moves faster than the edges in a very considerable proportion; quite contrary to the opinion generally entertained." he also announced at the same time the continuous hourly advance of the glacier. this letter bears the date, "courmayeur, piedmont, th july," but it was not published until the month of october following. meanwhile m. agassiz, in company with m. wild, returned to complete his experiment upon the glacier of the aar. on the th of july, , the displacements of the six piles which he had planted the year before were determined by means of a theodolite. of the three upon the finsteraar affluent, that nearest the side had moved feet, the next feet, while that nearest to the centre had moved feet. of those on the lauteraar, that nearest the side had moved feet, the next feet, and that nearest the centre feet. these observations were perfectly conclusive as to the quicker motion of the centre: they embrace a year's motion; and the magnitude of the displacements, causing errors of inches, which might seriously affect small displacements, to vanish, justifies us in ranking this experiment with the most satisfactory of the kind that have ever been made. the results were communicated to arago in a letter dated from the glacier of the aar, on the st of august, ; they were laid before the academy of sciences on the th of august, , and are published in the 'comptes rendus' of the same date. the facts, then, so far as i have been able to collect them, are as follows:--m. agassiz commenced his experiment about ten months before professor forbes, and the results of his measurements, with quantities stated, were communicated to the french academy about two months prior to the publication of the letter of professor forbes in the 'edinburgh philosophical journal.' but the latter communication, announcing in general terms the fact of the speedier central motion, was dated from courmayeur twenty-seven days before the date of m. agassiz's letter from the glacier of the aar. [sidenote: state of the question.] the speedier motion of the central portion of a glacier has been justly regarded as one of cardinal importance, and no other observation has been the subject of such frequent reference; but the general impression in england is that m. agassiz had neither part nor lot in the establishment of the above fact; and in no english work with which i am acquainted can i find any reference to the above measurements. relying indeed upon such sources for my information, i remained ignorant of the existence of the paper in the 'comptes rendus' until my attention was directed to it by professor wheatstone. in the next following chapters i shall have to state the results of some of my own measurements, and shall afterwards devote a little time to the consideration of the cause of glacier-motion. in treating a question on which so much has been written, it is of course impossible, as it would be undesirable, to avoid subjecting both my own views and those of others to a critical examination. but in so doing i hope that no expression shall escape me inconsistent with the courtesy which ought to be habitual among philosophers or with the frank recognition of the just claims of my predecessors. motion of the mer de glace. ( .) [sidenote: my first observation.] on tuesday, the th of july, , i made my first observation on the motion of the mer de glace. accompanied by mr. hirst i selected on the steep slope of the glacier des bois a straight pinnacle of ice, the front edge of which was perfectly vertical. in coincidence with this edge i fixed the vertical fibre of the theodolite, and permitted the instrument to stand for three hours. on looking through it at the end of this interval, the cross hairs were found projected against the white side of the pyramid; the whole mass having moved several inches downwards. the instrument here mentioned, which had long been in use among engineers and surveyors, was first applied to measure glacier-motion in ; by prof. forbes on the mer de glace, and by m. agassiz on the glacier of the aar. the portion of the theodolite made use of is easily understood. the instrument is furnished with a telescope capable of turning up and down upon a pivot, without the slightest deviation right or left; and also capable of turning right or left without the slightest deviation up or down. within the telescope two pieces of spider's thread, so fine as to be scarcely visible to the naked eye, are drawn across the tube and across each other. when we look through the telescope we see these fibres, their point of intersection being exactly in the centre of the tube; and the instrument is furnished with screws by means of which this point can be fixed upon any desired object with the utmost precision. [sidenote: mode of measurement.] in setting a straight row of stakes across the glacier, our mode of proceeding was in all cases this:--the theodolite was placed on the mountain-side flanking the glacier, quite clear of the ice; and having determined the direction of a line perpendicular to the axis of the glacier, a well-defined object was sought at the opposite side of the valley as close as possible to this direction; the object being, in some cases, the sharp edge of a cliff; in others, a projecting corner of rock; and, in others, a well-defined mark on the face of the rock. this object and those around it were carefully sketched, so that on returning to the place it could be instantly recognized. on commencing a line the point of intersection of the two spiders' threads within the telescope was first fixed accurately upon the point thus chosen, and an assistant carrying a straight bâton was sent upon the ice. by rough signalling he first stood near the place where the first stake was to be driven in; and the object end of the telescope was then lowered until he came within the field of view. he held his staff upright upon the ice, and, in obedience to signals, moved upwards or downwards until the point of intersection of the spiders-threads exactly hit the bottom of the bâton; a concerted signal was then made, the ice was pierced with an auger to a depth of about sixteen inches, and a stake about two feet long was firmly driven into it. the assistant then advanced for some distance across the glacier; the end of the telescope was now gently raised until he and his upright staff again appeared in the field of view. he then moved as before until the bottom of his staff was struck by the point of intersection, and here a second stake was fixed in the ice. in this way the process was continued until the line of stakes was completed. before quitting the station, a plummet was suspended from a hook directly underneath the centre of the theodolite, and the place where the point touched the ground was distinctly marked. to measure the motion of the line of stakes, we returned to the place a day or two afterwards, and by means of the plummet were able to make the theodolite occupy the exact position which it occupied when the line was set out. the telescope being directed upon the point at the opposite side of the valley, and gradually lowered, it was found that no single stake along the line preserved its first position: they had all shifted downwards. the assistant was sent to the first stake; the point which it had first occupied was again determined, and its present distance from that point accurately measured. the same thing was done in the case of each stake, and thus the displacement of the whole row of stakes was ascertained.[a] the time at which the stake was fixed, and at which its displacement was measured, being carefully noted, a simple calculation determined _the daily motion_ of the stake. [sidenote: the first line.] thus, on the th of july, , we set out our first line across the mer de glace, at some distance below the montanvert; on the day following we measured the progress of the stakes. the observed displacements are set down in the following table:-- first line.--daily motion. no. of stake. inches. west moved - / " - / " - / " ... " - / moved ... " - / " ... " - / " - / east. [sidenote: the centre-point not the quickest.] the theodolite in this case stood on the montanvert side of the valley, and the stakes are numbered from this side. we see that the motion gradually augments from the st stake onward--the st stake being held back by the friction of the ice against the flanking mountain-side. the stakes , , and have no motion attached to them, as an accident rendered the measurement of their displacements uncertain. but one remarkable fact is exhibited by this line; the th stake stood upon the _middle_ of the glacier, and we see that its motion is by no means the quickest; it is exceeded in this respect by the stakes and . the portion of the glacier on which the th stake stood was very much cut up by crevasses, and, while the assistant was boring it with his auger, the ice beneath him was observed, through the telescope, to slide suddenly forward for about inches. the other stakes retained their positions, so that the movement was purely local. deducting the inches thus irregularly obtained, we should have a daily motion of - / inches for stake no. . the place was watched for some time, but the slipping was not repeated; and a second measurement on the succeeding day made the motion of the th stake inches, whilst that of the centre of the glacier was only . here, then, was a fact which needed explanation; but, before attempting this, i resolved, by repeated measurements in the same locality, to place the existence of the fact beyond doubt. we therefore ascended to a point upon the old and now motionless moraine, a little above the montanvert hotel; and choosing, as before, a well-defined object at the opposite side of the valley, we set between it and the theodolite a row of twenty stakes across the glacier. their motions, measured on a subsequent day, and reduced to their daily rate, gave the results set down in the following table:-- second line.--daily motion. no. of stake. inches. west moved - / " - / " - / " - / " " - / " - / " " - / " moved " - / " " - / " - / " - / " - / " - / " ... " - / east. [sidenote: corroborative measurements.] as regards the retardation of the side, we observe here the same fact as that revealed by our first line--the motion gradually augments from the first stake to the last. the stake no. stood upon the dirty portion of the ice, which was derived from the talèfre tributary of the mer de glace, and far beyond the middle of the glacier. these measurements, therefore, corroborate that made lower down, as regards the non-coincidence of the point of swiftest motion with the centre of the glacier. but it will be observed that the measurements do not show any retardation of the ice at the eastern extremity of the line of stakes--the motion goes on augmenting from the first stake to the last. the reason of this is, that in neither of the cases recorded were we able to get the line quite across the glacier; the crevasses and broken ice-ridges, which intercepted the vision, compelled us to halt before we came sufficiently close to the eastern side to make its retardation sensible. but on the th of july my friend hirst sought out an elevated station on the chapeau, or eastern side of the valley, whence he could command a view from side to side over all the humps and inequalities of the ice, the fixed point at the opposite side, upon which the telescope was directed, being the corner of a window of the montanvert hotel. along this line were placed twelve stakes, the daily motions of which were found to be as follows:-- third line.--daily motion. no. of stake. inches. east moved - / " - / " - / " - / " - / " - / moved - / " " " " ... " - / west. the numbering of the stakes along this line commenced from the chapeau-side of the glacier, and the retardation of that side is now manifest enough; the motion gradually augmenting from - / to - / inches. but, comparing the velocity of the two extreme stakes, we find that the retardation of stake is much greater than that of stake . stake , moreover, which moved with the _maximum_ velocity, was not upon the centre of the glacier, but much nearer to the eastern than to the western side. [sidenote: a new peculiarity of glacier motion.] it was thus placed beyond doubt that the point of maximum motion of the mer de glace, at the place referred to, is not the centre of the glacier. but, to make assurance doubly sure, i examined the comparative motion along three other lines, and found in all the same undeviating result. this result is not only unexpected, but is quite at variance with the opinions hitherto held regarding the motion of the mer de glace. the reader knows that the trunk-stream is composed of three great tributaries from the géant, the léchaud, and the talèfre. the glacier du géant fills more than half of the trunk-valley, and the junction between it and its neighbours is plainly marked by the dirt upon the surface of the latter. in fact four medial moraines are crowded together on the eastern side of the glacier, and before reaching the montanvert they have strewn their débris quite over the adjacent ice. a distinct limit is thus formed between the clean glacier du géant and the other dirty tributaries of the trunk-stream. now the eastern side of the mer de glace is observed on the whole to be much more fiercely torn than the western side, and this excessive crevassing has been referred to _the swifter motion of the glacier du géant_. it has been thought that, like a powerful river, this glacier drags its more sluggish neighbours after it, and thus tears them in the manner observed. but the measurement of the foregoing three lines shows that this cannot be the true cause of the crevassing. in each case the stakes which moved quickest _lay upon the dirty portion of the trunk-stream_, far to the east of the line of junction of the glacier du géant, which in fact moved slowest of all. [sidenote: law of motion sought.] the general view of the glacier, and of the shape of the valley which it filled, suggested to me that the analogy with a river might perhaps make itself good beyond the limits hitherto contemplated. the valley was not straight, but sinuous. at the montanvert the convex side of the glacier was turned eastward; at some distance higher up, near the passages called _les ponts_, it was turned westward; and higher up again it was turned once more, for a long stretch, eastward. thus between trélaporte and the ponts we had what is called a point of contrary flexure, and between the ponts and the montanvert a second point of the same kind. [sidenote: conjecture regarding change of flexure.] supposing a river, instead of the glacier, to sweep through this valley; _its_ point of maximum motion would not always remain central, but would deviate towards that side of the valley to which the river turned its convex boundary. indeed the positions of towns along the banks of a navigable river are mainly determined by this circumstance. they are, in most cases, situate on the convex sides of the bends, where the rush of the water prevents silting up. can it be then that the ice exhibits a similar deportment? that the same principle which regulates the distribution of people along the banks of the thames is also acting with silent energy amid the glaciers of the alps? if this be the case, the position of the point of maximum motion ought, of course, to shift with the bending of the glacier. opposite the ponts, for example, the point ought to be on the glacier du géant, and westward of the centre of the trunk-stream; while, higher up, we ought to have another change to the eastern side, in accordance with the change of flexure. on the th of july a line was set out across the glacier, one of its fixed termini being a mark upon the first of the three ponts. the motion of this line, measured on a subsequent day, and reduced to its daily rate, was found to be as follows:-- fourth line.--daily motion. no. of stake. inches. east moved - / " " - / " - / " - / " - / " - / " - / " - / moved " - / " - / " - / " " - / " - / " west. this line, like the third, was set out and numbered from the eastern side of the glacier, the theodolite occupying a position on the heights of the echelets. a moment's inspection of the table reveals a fact different from that observed on the third line; _there_ the most easterly stake moved with more than twice the velocity of the most westerly one; _here_, on the contrary, the most westerly stake moves with more than twice the velocity of the most easterly one. to enable me to compare the motion of the eastern and western halves of the glacier with greater strictness, my able and laborious companion undertook the task of measuring with a surveyor's chain the line just referred to; noting the pickets which had been fixed along the line, and the other remarkable objects which it intersected. the difficulty of thus directing a chain over crevasses and ridges can hardly be appreciated except by those who have tried it. nevertheless, the task was accomplished, and the width of the mer de glace, at this portion of its course, was found to be yards, or almost exactly half a mile. referring to the last table, it will be seen that the two stakes numbered and moved with a common velocity of - / inches per day, and that their motion is swifter than that of any of the others. the point of swiftest motion may be taken midway between them, and this point was found by measurement to lie yards _west_ of the dirt which marked the junction of the glacier du géant with its fellow tributaries: whereas, in the former cases, it lay a considerable distance _east_ of this limit. its distance from the eastern side of the glacier was yards, and from the western side yards, being yards west of the centre of the glacier. [sidenote: conjecture tested.] but the measurements enabled me to take the stakes in pairs, and to compare the velocity of a number of them which stood at certain distances from the eastern side of the valley, with an equal number which stood at the same distances from the western side. by thus arranging the points two by two, i was able to compare the motion of the entire body of the ice at the one side of the central line with that of the ice at the other side. stake stood about as far from the western side of the glacier as stake did from its eastern side; occupied the same relation to ; , to ; , to ; and , to . calling each pair of points which thus stand at equal distances from the opposite sides _corresponding points_, the following little table exhibits their comparative motions:-- numbers and velocities of corresponding points on the fourth line. no. vel. no. vel. no. vel. no. vel. no. vel. west - / - / - / - / east - / - / - / - / - / [sidenote: western half moves quickest.] the table explains itself. we see that while stake , which stands _west_ of the centre, moves inches, stake , which stands an equal distance _east_ of the centre, moves only - / inches. comparing every pair of the other points, we find the same to hold good; the western stake moves in each case faster than the corresponding eastern one. hence, _the entire western half of the mer de glace, at the place crossed by our fourth line, moves more quickly than the eastern half of the glacier_. we next proceeded farther up, and tested the contrary curvature of the glacier, opposite to trélaporte. the station chosen for this purpose was on a grassy platform of the promontory, whence, on the th of july, a row of stakes was fixed at right angles to the axis of the glacier. their motions, measured on the st, gave the following results:-- fifth line.[b]--daily motion. no. of stake. inches. west moved - / " - / " - / " " - / " " - / " - / moved - / " " - / " - / " " - / " east. this line was set out and numbered from the trélaporte side of the valley, and was also measured by mr. hirst, over boulders, ice-ridges, chasms, and moraines. the entire width of the glacier here was found to be yards, or somewhat wider than it is at the ponts. it will also be observed that its motion is somewhat slower. an inspection of the notes of this line showed me that stakes and , and , and , were "corresponding points;" the first of each pair standing as far from the western side, as the second stood from the eastern. in the following table these points and their velocities are arranged exactly as in the case of the fourth line. numbers and velocities of the corresponding points on the fifth line. no. vel. no. vel. no. vel. west - / - / east - / - / [sidenote: eastern half moves quickest.] in each case we find that the stake on the eastern side moves more quickly than the corresponding one upon the western side: so that where the fifth line crosses the glacier _the eastern half of the mer de glace moves more quickly than the western half_. this is the reverse of the result obtained at our fourth line, but it agrees with that obtained on our first three lines, where the curvature of the valley is similar. the analogy between a river and a glacier moving through a sinuous valley is therefore complete. supposing the points of maximum motion to be determined for a great number of lines across the glacier, the line uniting all these points is what mathematicians would call the _locus_ of the point of maximum motion. at trélaporte this line would lie east of the centre; at the ponts it would lie west of the centre; hence, in passing from trélaporte to the ponts, it must cross the axis of the glacier. again, at the montanvert, it would lie east of the centre, and between the ponts and the montanvert the axis of the glacier would be crossed a second time. supposing the dotted line in fig. to represent the middle line of the glacier, then the defined line would represent the locus of the point of maximum motion. _it is a curve more deeply sinuous than the valley itself, and it crosses the axis of the glacier at each point of contrary flexure._ [sidenote: locus of point of swiftest motion.] [illustration: fig. . locus of the point of maximum motion.] to complete our knowledge of the motion of the mer de glace, we afterwards determined the velocity of its two accessible tributaries--the glacier du géant, and the glacier de léchaud. on the th of july, a line of stakes was set out across the former, a little above the tacul, and their motion was subsequently found to be as follows: sixth line.--daily motion. no. of stake. inches. moved " " " " moved - / " - / " " " the width of the glacier at this place we found to be yards, and its maximum velocity, as shown by the foregoing table, inches a day. on the st of august a line was set out across the glacier de léchaud, above its junction with the talèfre: it commenced beneath the block of stone known as the pierre de béranger. the displacements of the stakes, measured on the rd of august, gave the following results:-- seventh line.--daily motion. no. of stake. inches. moved - / " - / " - / " " - / moved - / " - / " - / " " - / the width of the glacier de léchaud at this place was found to be yards; its maximum motion, as shown by the table, being - / inches a day. this is the slowest rate which we observed upon either the mer de glace or its tributaries. the width of the talèfre-branch, as it descends the cascade, or, in other words, before it is influenced by the pressure of the léchaud, was found approximately to be yards. [sidenote: squeezing at trÉlaporte.] the widths of the tributaries were determined for the purpose of ascertaining the amount of lateral compression endured by the ice in its passage through the neck of the valley at trélaporte. adding all together we have-- géant yards. léchaud " talèfre " total yards. these three branches, as shown by the actual measurement of our th line, are forced at trélaporte through a channel yards wide; the width of the trunk stream is a little better than one-third of that of its tributaries, and it passes through this gorge at a velocity of nearly inches a day. [sidenote: the lÉchaud a driblet.] limiting our view to one of the tributaries only, the result is still more impressive. previous to its junction with the talèfre, the glacier de léchaud stretches before the observer as a broad river of ice, measuring yards across: at trélaporte it is squeezed, in a frozen vice, between the talèfre on one side and the géant on the other, to a driblet, measuring yards in width, or about one-tenth of its former transverse dimension. it will of course be understood that it is the _form_ and not the _volume_ of the glacier that is affected to this enormous extent by the pressure. supposing no waste took place, the glacier de léchaud would force precisely the same amount of ice through the "narrows" at trélaporte, in one day, as it sends past the pierre de béranger. at the latter place its velocity is about half of what it is at the former, but its width is more than nine times as great. hence, if no waste took place, its _depth_, at trélaporte, would be at _least_ - / times its depth opposite the pierre de béranger. superficial and subglacial melting greatly modify this result. still i think it extremely probable that observations directed to this end would prove the comparative shallowness of the upper portions of the glacier de léchaud. footnotes: [a] great care is necessary on the part of the man who measures the displacements. the staff ought to be placed along the original line, and the assistant ought to walk along it until the foot of a _perpendicular_ from the stake is attained. when several days' motion is to be measured, this precaution is absolutely necessary; the eye being liable to be grossly deceived in _guessing_ the direction of a perpendicular. [b] the details of the measurement of the fourth and fifth lines are published in the 'philosophical transactions,' vol. cxlix., p. . ice-wall at the tacul. velocities of top and bottom. ( .) as regards the motion of the _surface_ of a glacier, two laws are to be borne in mind: st, that regarding the quicker movement of the centre; nd, that regarding the locus of the point of maximum motion. our next care must be to compare the motion of the surface of a glacier with the motion of those parts which lie near its bed. rendu first surmised that the bottom of the glacier was retarded by friction, and both professor forbes[a] and m. martins[b] have confirmed the conjecture. theirs are the only observations which we possess upon the subject; and i was particularly desirous to instruct myself upon this important head by measurements of my own. [sidenote: first attempt at measurement.] during the summer of the eastern side of the glacier du géant, near the tacul, exposed a nearly vertical precipice of ice, measuring feet from top to bottom. i requested mr. hirst to fix two stakes in the same vertical plane, one at the top of the precipice and one near the bottom. this he did upon the rd of august, and on the th i accompanied him to measure the progress of the stakes. on the summit of the precipice, and running along it, was the lateral moraine of the glacier. the day was warm and the ice liquefying rapidly, so that the boulders and débris, deprived incessantly of their support, came in frequent leaps and rushes down the precipice. into this peril my guide was about to enter, to measure the displacement of the lower stake, while i was to watch, and call out the direction in which he was to run when a stone gave way. but i soon found that the initial motion was no sure index of the final motion. by striking the precipice, the stones were often deflected, and carried wide of their original direction. i therefore stopped the man, and sent him to the summit of the precipice to remove all the more dangerous blocks. this accomplished, he descended, and while i stood beside him, executed the required measurement. from the rd to the th of august the upper stake had moved twelve inches, and the lower one six. unfortunately some uncertainty attached itself to this result, due to the difficulty of fixing the lower stake. the guide's attention had been divided between his work and his safety, and he had to retreat more than a dozen times from the falling boulders and débris. i, on the other hand, was unwilling to accept an observation of such importance with a shade of doubt attached to it. hence arose the desire to measure the motion myself. on the th of august i therefore reascended to the tacul, and fixed a stake at the top of the precipice, and another at the bottom. while sitting on the old moraine looking at the two pickets, the importance of determining the motion of a point midway between the top and bottom forcibly occurred to me, but, on mentioning it to my guide, he promptly pronounced any attempt of the kind absurd. [sidenote: stakes fixed at top, bottom, and centre.] on scanning the place carefully, however, the value of the observation appeared to me to outweigh the amount of danger. i therefore took my axe, placed a stake and an auger against my breast, buttoned my coat upon them, and cut an oblique staircase up the wall of ice, until i reached a height of forty feet from the bottom. here the position of the stake being determined by mr. hirst, who was at the theodolite, i pierced the ice with the auger, drove in the stake, and descended without injury. during the whole operation however my guide growled audibly. on the following morning we commenced the ascent of mont blanc, a narrative of which is given in part i. we calculated on an absence of three days, and estimated that the stakes which had just been fixed would be ready for measurement on our return; but we did not reach chamouni until the afternoon of friday, the th. heavy clouds settled, during our descent, upon the summits behind us, and a thunder-peal from the aiguilles soon heralded a fall of rain, which continued without intermission till the afternoon of the th, when the atmosphere cleared, and showed the mountains clothed to their girdles with snow. the montanvert was thickly covered, and on our way to it we met the servants in charge of the cattle, which had been driven below the snow-line to obtain food. [sidenote: through gloom to the tacul.] on monday morning, the th, a dense fog filled the valley of the mer de glace. i watched it anxiously. the stakes which we had set at the tacul had been often in my thoughts, and i wished to make some effort to save the labour and peril incurred in setting them from being lost. i therefore set out, in one of the clear intervals, accompanied by my friend and simond, determined to measure the motion of the stakes, if possible, or to fix them more firmly, if they still stood. as we passed, however, from l'angle to the glacier, the fog became so dense and blinding that we halted. at my request mr. hirst returned to the montanvert; and simond, leaving the theodolite in the shelter of a rock, accompanied me through the obscurity to the tacul. we found the topmost stake still stuck by its point in the ice; but the two others had disappeared, and we afterwards discovered their fragments in a snow-buttress, which reared itself against the base of the precipice. they had been hit by the falling stones, and crushed to pieces. having thus learned the worst, we descended to the montanvert amid drenching rain. [sidenote: descent of boulders.] on the morning of the th there was no cloud to be seen anywhere, and the sunlight glistened brightly on the surface of the ice. we ascended to the tacul. the spontaneous falling of the stones appeared more frequent this morning than i had ever seen it. the sun shone with unmitigated power upon the ice, producing copious liquefaction. the rustle of falling débris was incessant, and at frequent intervals the boulders leaped down the precipice, and rattled with startling energy amid the rocks at its base. i sent simond to the top to remove the looser stones; he soon appeared, and urged the moraine-shingle in showers down the precipice, upon a bevelled slope of which some blocks long continued to rest. they were out of the reach of the guide's bâton, and he sought to dislodge them by sending other stones down upon them. some of them soon gave way, drawing a train of smaller shingle after them; others required to be hit many times before they yielded, and others refused to be dislodged at all. i then cut my way up the precipice in the manner already described, fixed the stake, and descended as speedily as possible. we afterwards fixed the bottom stake, and on the th the displacements of all three were measured.[c] the spaces passed over by the respective stakes in hours were found to be as follows:-- inches. top stake . middle stake . bottom stake . [sidenote: motion of stakes.] the height of the precipice was . feet, but it sloped off at its upper portion. the height of the middle stake above the ground was feet, and of the bottom one feet. it is therefore proved by these measurements that the bottom of the ice-wall at the tacul moves with less than half the velocity of the top; while the displacement of the intermediate stake shows how the velocity gradually increases from the bottom upwards. footnotes: [a] 'edinb. phil. journ.,' oct. , p. . [b] agassiz, 'système glaciaire,' p. . [c] on this latter occasion my guide volunteered to cut the steps for me up to the pickets; and i permitted him to do so. in fact, he was at least as anxious as myself to see the measurement carried out. winter motion of the mer de glace. ( .) the winter measurements were executed in the manner already described, on the th and th of december, . the theodolite was placed on the mountain's side flanking the glacier, and a well-defined object was chosen at the opposite side of the valley, so that a straight line between this object and the theodolite was approximately perpendicular to the axis of the glacier. fixing the telescope in the first instance with its cross hairs upon the object, its end was lowered until it struck the point upon the glacier at which a stake was to be fixed. thanks to the intelligence of my assistants, after the fixing of the first stake they speedily took up the line at all other points, requiring very little correction to make their positions perfectly accurate. on the day following that on which the stakes were driven in, the theodolite was placed in the same position, and the distances to which the stakes had moved from their original positions were accurately determined. as already stated, the first line crossed the glacier about yards above the montanvert hotel. [sidenote: half of summer motion.] line no. i.--winter motion in twenty-four hours. no. of stake. inches. west - / - / - / - / - / - / - / - / east. [sidenote: the same law in summer and winter.] the maximum here is fifteen and three-quarters inches; the maximum summer motion of the same portion of the glacier is about thirty inches. these measurements also show that in winter, as well as in summer, the side of the glacier opposite to the montanvert moves quicker than that adjacent to it. the stake which moved with the maximum velocity was beyond the moraine of la noire. the second line crossed the glacier about yards below the montanvert. line no. ii.--winter motion in twenty-four hours. no. of stake. inches. - / - / - / - / - / - / - / the maximum here is an inch and three-quarters greater than that of line no. . the summer maximum at this portion of the glacier also exceeds that of the part intersected by line no. . the surface of the glacier between the two lines is in a state of tension which relieves itself by a system of transverse fissures, and thus permits of the quicker advance of the forward portion. my desire, in making these measurements, was, in the first place, to raise the winter observations of the motion to the same degree of accuracy as that already possessed by the summer ones. auguste balmat had already made a series of winter observations on the mer de glace; but they were made in the way employed before the introduction of the theodolite by agassiz and forbes, and shared the unavoidable roughness of such a mode of measurement. they moreover gave us no information as to the motion of the different parts of the glacier along the same transverse line, and this, for reasons which will appear subsequently, was the point of chief interest to me. cause of glacier-motion. de saussure's theory. ( .) perhaps the first attempt at forming a glacier-theory is that of scheuchzer in . he supposed the motion to be caused by the conversion of water into ice within the glacier; the known and almost irresistible expansion which takes place on freezing, furnishing the force which pushed the glacier downward. this idea was illustrated and developed with so much skill by m. de charpentier, that his name has been associated with it; and it is commonly known as the theory of charpentier, or the dilatation-theory. m. agassiz supported this theory for a time, but his own thermometric experiments show us that the body of the glacier is at a temperature of ° fahr.; that consequently there is no interior magazine of cold to freeze the water with which the glacier is supposed to be incessantly saturated. so that these experiments alone, if no other grounds existed, would prove the insufficiency of the theory of dilatation. i may however add, that the arguments most frequently urged against this theory deal with an assumption, which i do not think its author ever intended to make. [sidenote: the glacier slides.] another early surmise was that of altmann and grüner ( ), both of whom conjectured that the glacier slid along its bed. this theory received distinct expression from de saussure in ; and has since been associated with the name of that great alpine traveller, being usually called the 'theory of saussure,' and sometimes the 'sliding theory.' it is briefly stated in these words:-- "almost every glacier reposes upon an inclined bed, and those of any considerable size have beneath them, even in winter, currents of water which flow between the ice and the bed which supports it. it may therefore be understood that these frozen masses, drawn down the slope on which they repose, disengaged by the water from all adhesion to the bottom, sometimes even raised by this water, must glide by little and little, and descend, following the inclinations of the valleys, or of the slopes which they cover. it is this slow but continual sliding of the ice on its inclined base which carries it into the lower valleys."[a] [sidenote: strained interpretation.] de saussure devoted but little time to the subject of glacier-motion; and the absence of completeness in the statement of his views, arising no doubt from this cause, has given subsequent writers occasion to affix what i cannot help thinking a strained interpretation to the sliding theory. it is alleged that he regarded a glacier as a perfectly rigid body; that he considered it to be "a mass of ice of small depth, and considerable but uniform breadth, sliding down a uniform valley, or pouring from a narrow valley into a wider one."[b] the introduction "of the smallest flexibility or plasticity" is moreover emphatically denied to him.[c] it is by no means probable that the great author of the 'voyages' would have subscribed to this "rigid" annotation. his theory, be it remembered, is to some extent _true_: the glacier moves over its bed in the manner supposed, and the rocks of britain bear to this day the traces of these mighty sliders. de saussure probably contented himself with a general statement of what he believed to be the substantial cause of the motion. he visited the jardin, and saw the tributaries of the mer de glace turning round corners, welding themselves together, and afterwards moving through a sinuous trunk-valley; and it is scarcely credible that in the presence of such facts he would have denied all flexibility to the glacier. the statement that he regarded a glacier to be a mass of ice of uniform width, is moreover plainly inconsistent with the following description of the glacier of mont dolent: "its most elevated plateau is a great circus, surrounded by high cliffs of granite, of pyramidal forms; thence the glacier descends through a gorge, in which _it is narrowed_; but after having passed the gorge, it _enlarges again_, spreading out like a fan. thus it has on the whole the form of a sheaf tied in the middle and dilated at its two extremities."[d] [sidenote: glacier of mont dolent.] curiously enough this very glacier, and these very words, are selected by m. rendu as illustrative of the plasticity of glaciers. "nothing," he says, "shows better the extent to which a glacier moulds itself to its locality than the form of the glacier of mont dolent in the valley of ferret;" and he adds, in connexion with the same passage, these remarkable words:--"there is a multitude of facts which would seem to necessitate the belief that the substance of glaciers enjoys a kind of ductility which permits it to mould itself to the locality which it occupies, to grow thin, to swell, and to narrow itself like a soft paste."[e] footnotes: [a] 'voyages,' § . [b] james d. forbes, 'occasional papers on the theory of glaciers,' , p. . [c] "i adhere to the definition as excluding the introduction of the smallest flexibility or plasticity." 'occ. pap.,' p. . [d] 'voyages,' tome ii. p. . [e] in connexion with this brief sketch of the 'sliding theory,' it ought to be stated, that mr. hopkins has proved experimentally, that ice may descend an incline at a sensibly uniform rate, and that the velocity is augmented by increasing the weight. in this remarkable experiment the motion was due to the slow disintegration of the lower surface of the ice. see 'phil. mag.,' , vol. . rendu's theory. ( .) [sidenote: rendu's character.] m. rendu, bishop of annecy, to whose writings i have just referred, died last autumn.[a] he was a man of great repute in his diocese, and we owe to him one of the most remarkable essays upon glaciers that have ever appeared. his knowledge was extensive, his reasoning close and accurate, and his faculty of observation extraordinary. with these were associated that intuitive power, that presentiment concerning things as yet untouched by experiment, which belong only to the higher class of minds. throughout his essay a constant effort after quantitative accuracy reveals itself. he collects observations, makes experiments, and tries to obtain numerical results; always taking care, however, so to state his premises and qualify his conclusions that nobody shall be led to ascribe to his numbers a greater accuracy than they merit. it is impossible to read his work, and not feel that he was a man of essentially truthful mind, and that science missed an ornament when he was appropriated by the church. the essay above referred to is printed in the tenth volume of the memoirs of the royal academy of sciences of savoy, published in , and is entitled, '_théorie des glaciers de la savoie, par m. le chanoine rendu, chevalier du mérite civil et secrétaire perpétuel_.' the paper had been written for nearly two years, and might have remained unprinted, had not another publication on the same subject called it forth. i will place a few of the leading points of this remarkable production before the reader; commencing with a generalization which is highly suggestive of the character of the author's mind. [sidenote: "theorie des glaciers de la savoie."] he reflects on the accumulation of the mountain-snows, each year adding fifty-eight inches of ice to a glacier. this would make mont blanc four hundred feet higher in a century, and four thousand feet higher in a thousand years. "it is evident," he says, "that nothing like this occurs in nature." the escape of the ice then leads him to make some general remarks on what he calls the "law of circulation." "the conserving will of the creator has employed for the permanence of his work the great law of _circulation_, which, strictly examined, is found to reproduce itself in all parts of nature. the waters circulate from the ocean to the air, from the air to the earth, and from the earth to the ocean.... the elements of organic substances circulate, passing from the solid to the liquid or aëriform condition, and thence again to the state of solidity or of organisation. that universal agent which we designate by the names of fire, light, electricity, and magnetism, has probably also a _circulation_ as wide as the universe." the italics here are rendu's own. this was published in , but written, we are informed, nearly two years before. in mr. grove wrote thus:--"light, heat, magnetism, motion, and chemical affinity, are all convertible material affections." more recently helmholtz, speaking of the "circuit" formed by "heat, light, electricity, magnetism, and chemical affinity," writes thus:--"starting from each of these different manifestations of natural forces, we can set every other in action." i quote these passages because they refer to the same agents as those named by m. rendu, and to which he ascribes "_circulation_." can it be doubted that this savoyard priest had a premonition of the conservation of force? i do not want to lay more stress than it deserves upon a conjecture of this kind; but its harmony with an essay remarkable for its originality gives it a significance which, if isolated, it might not possess. [sidenote: glaciers rightly divided.] with regard to the glaciers, rendu commences by dividing them into two kinds, or rather the selfsame glacier into two parts, one of which he calls the "_glacier réservoir_," the other the "_glacier d'écoulement_,"--two terms highly suggestive of the physical relationship of the _névé_ and the glacier proper. he feeds the reservoirs from three sources, the principal one of which is the snow, to which he adds the rain, and the vapours which are condensed upon the heights without passing into the state of either rain or snow. the conversion of the snow into ice he supposes to be effected by four different causes, the most efficacious of which is _pressure_.[b] it is needless to remark that this quite agrees with the views now generally entertained. in page of the volume referred to there is a passage which shows that the "veined structure" of the glacier had not escaped him, though it would seem that he ascribed it to stratification. "when," he writes, "we perceive the profile of a glacier on the walls of a crevasse, we see different layers distinct in colour, but more particularly in density; some seem to have the hardness, as they have the greenish colour, of glass; others preserve the whiteness and porosity of the snow." there is also a very close resemblance between his views of the influence of "time and cohesion" and those of prof. forbes. "we may conclude," he writes, "that _time_, favouring the action of _affinity_, and the pressure of the layers one upon the other, causes the little crystals of which snow is composed to approach each other, bring them into contact, and convert them into ice."[c] regelation also appears to have attracted his notice.[d] "when we fill an ice-house," he writes, "we break the ice into very small fragments; afterwards we wet it with water or degrees above zero (cent.) in temperature; but, notwithstanding this, the whole is converted into a compact mass of ice." he moreover maintains, in almost the same language as prof. forbes,[e] the opinion, that ice has always an inner temperature lower than zero (cent.). he believed this to be a property "inherent to ice." "never," he says, "can a calorific ray pass the first surface of ice to raise the temperature of the interior."[f] [sidenote: observations and hypotheses.] he notices the direction of the glacier as influencing the wasting of its ridges by the sun's heat; ascribing to it the effect to which i have referred in explaining the wave-like forms upon the surface of the mer de glace. his explanation of the moulins, too, though insufficient, assigns a true cause, and is an excellent specimen of physical reasoning. with regard to the diminution of the _glaciers réservoirs_, or, in other words, to the manner in which the ice disappears, notwithstanding the continual additions made to it, we have the following remarkable passage:--"in seeking the cause of the diminution of glaciers, it has occurred to my mind that the ice, notwithstanding its hardness and its rigidity, can only support a given pressure without breaking or being squeezed out. according to this supposition, whenever the pressure exceeds that force, there will be rupture of the ice, and a flow in consequence. let us take, at the summit of mont blanc, a column of ice reposing on a horizontal base. the ice which forms the first layer of that column is compressed by the weight of all the layers above it; but if the solidity of the said first layer can only support a weight equal to , when the weight exceeds this amount there will be rupture and spreading out of the ice of the base. now, something very similar occurs in the immense crust of ice which covers the summits of mont blanc. this crust appears to augment at the upper surface and to diminish by the sides. to assure oneself that the movement is due to the force of pressure, it would be necessary to make a series of experiments upon the solidity of ice, such as have not yet been attempted."[g] i may remark that such experiments substantially verify m. rendu's notion. but it is his observations and reasoning upon the _glaciers d'écoulement_ that chiefly interest us. the passages in his writings where he insists upon the power of the glaciers to mould themselves to their localities, and compares them to a soft paste, to lava at once ductile and liquid, are well known from the frequent and flattering references of professor forbes; but there are others of much greater importance, which have hitherto remained unknown in this country. regarding the motion of the mer de glace, rendu writes as follows:-- [sidenote: measurement of motion.] [sidenote: the sides of the glacier retarded.] "i sought to appreciate the quantity of its motion; but i could only collect rather vague data. i questioned my guides regarding the position of an enormous rock at the edge of the glacier, but still upon the ice, and consequently partaking of its motion. the guides showed me the place where it stood the preceding year, and where it had stood two, three, four, and five years previously; they showed me the place where it would be found in a year, in two years, &c.; _so certain are they of the regularity of the motion_. their reports, however, did not always agree precisely with each other, and their indications of time and distance lack the precision without which we proceed obscurely in the physical sciences. in reducing these different indications to a mean, i found the total advance of the glacier to be about feet a year. during my last journey i obtained more certain data, which i have stated in the preceding chapter. _the enormous difference between the two results arises from the fact that the latter observations were made at the centre of the glacier_, which moves more rapidly, _while the former were made at the side, where the ice_ is retained by the friction against its rocky walls."[h] an opinion, founded on a grave misapprehension which rendu enables us to correct, is now prevalent in this country, not only among the general public, but also among those of the first rank in science. the nature of the mistake will be immediately apparent. at page of the 'travels in the alps' its distinguished author gives a sketch of the state of our knowledge of glacier-motion previous to the commencement of his inquiries. he cites ebel, hugi, agassiz, bakewell, de la beche, shirwell, rendu, and places them in open contradiction to each other. rendu, he says, gives the motion of the mer de glace to be " feet per annum; feet per annum; a foot a day; feet per annum, and feet per annum, or _one-tenth_ of the last!" ... and he adds, "i was not therefore wrong in supposing that the actual progress of a glacier was yet a new problem when i commenced my observations on the mer de glace in ."[i] in the 'north british review' for august, , a writer equally celebrated for the brilliancy of his discoveries and the vigour of his pen, collected the data furnished by the above paragraph into a table, which he introduced to his readers in the following words:--"it is to professor forbes alone that we owe the first and most correct researches respecting the motion of glaciers; and in proof of this, we have only to give the following list of observations which had been previously made. observers. name of glacier. annual rate of motion. ebel chamouni feet ebel grindelwald " hugi aar " agassiz aar " bakewell mer de glace " de la beche mer de glace " shirwell mer de glace " m. rendu mer de glace " saussure's ladder mer de glace " ... such was the state of our knowledge when professor forbes undertook the investigation of the subject." i am persuaded that the writer of this article will be the first to applaud any attempt to remove an error which, advanced on his great authority, must necessarily be widely disseminated. the numbers in the above table certainly differ widely, and it is perhaps natural to conclude that such discordant results can be of no value; but the fact really is that _every one of them may be perfectly correct_. this fact, though overlooked by professor forbes, was clearly seen by rendu, who pointed out with perfect distinctness the sources from which the discrepancies were derived. [sidenote: discrepancies explained.] "it is easy," he says, "to comprehend that it is impossible to obtain a general measure,--that there ought to be one for each particular glacier. the nature of the slope, the number of changes to which it is subjected, the depth of the ice, the width of the couloir, the form of its sides, and a thousand other circumstances, must produce variations in the velocity of the glacier, and these circumstances cannot be everywhere absolutely the same. much more, it is not easy to obtain this velocity for a single glacier, and for this reason. in those portions where the inclination is steep, the layer of ice is thin, and its velocity is great; in those where the slope is almost nothing, the glacier swells and accumulates; the mass in motion being double, triple, &c., the motion is only the half, the third, &c. [sidenote: liquid motion ascribed to glacier.] "but this is not all," adds m. rendu: "_between the mer de glace and a river, there is a resemblance so complete that it is impossible to find in the latter a circumstance which does not exist in the former._ in currents of water the motion is not uniform, neither throughout their width nor throughout their depth; _the friction of the bottom, that of the sides_, the action of obstacles, cause the motion to vary, _and only towards the middle of the surface is this entire...._"[j] in professor forbes appears to have come to the same conclusion as m. rendu; for after it had been proved that the centre of the aar glacier moved quicker than the side in the ratio of fourteen to one, he accepted the result in these words:--"the movement of the centre of the glacier is to that of a point five mètres from the edge as fourteen to one: such is the effect of plasticity!"[k] indeed, if the differences exhibited in the table were a proof of error, the observations of professor forbes himself would fare very ill. the measurements of glacier-motion made with his own hands vary from less than feet a year to feet a year, the minimum being less than _one-twentieth_ of the maximum; and if we include the observations made by balmat, the fidelity of which has been certified by professor forbes, the minimum is only _one-thirty-seventh_ of the maximum. [sidenote: north british review.] there is another point connected with rendu's theory which needs clearing up:--"the idea," writes the eminent reviewer, "that a glacier is a semifluid body is no doubt startling, especially to those who have seen the apparently rigid ice of which it is composed. m. rendu himself shrank from the idea, and did not scruple to say that 'the rigidity of a mass of ice was in direct opposition to it;' and we think that professor forbes himself must have stood aghast when his fancy first associated the notion of imperfect fluidity with the solid or even the fissured ice of the glacier, and when he saw in his mind's eye the glaciers of the alps flowing like a river along their rugged bed. a truth like this was above the comprehension and beyond the sympathy of the age; and it required a moral power of no common intensity to submit it to the ordeal of a shallow philosophy, and the sneers of a presumptuous criticism." these are strong words; but the fact is that, so far from "shrinking" from the idea, rendu affirmed, with a clearness and an emphasis which have not been exceeded since, that all the phenomena of a river were reproduced upon the mer de glace; its deeps, its shallows, its widenings, its narrowings, its rapids, its places of slow motion, and the quicker flow of its centre than of its sides. he did not shrink from accepting a difference between the central and lateral motion amounting to a ratio of ten to one--a ratio so large that professor forbes at one time regarded the acceptance of it as a simple absurdity. in this he was perhaps justified; for his own first observations, which, however valuable, were hasty and incomplete, gave him a maximum ratio of about one and a half to one, while the ratio in some cases was nearly one of _equality_. the observations of agassiz however show that the ratio, instead of being ten to one, may be _infinity_ to one; for the lateral ice may be so held back by a local obstacle that in the course of a year it shall make no sensible advance at all. [sidenote: the ice and the glacier.] from one thing only did m. rendu shrink; and it is _the_ thing regarding which we are still disunited. he shrank from stating the physical quality of the ice in virtue of which a glacier moved like a river. he demands experiments upon snow and ice to elucidate this subject. the very observations which professor forbes regards as proofs are those of which we require the physical explanation. it is not the viscous flow, if you please to call it such, of the glacier as a whole that here concerns us; but it is the quality of the _ice_ in virtue of which this kind of motion is accomplished. professor forbes sees this difference clearly enough: he speaks of "fissured ice" being "flexible" in hand specimens; he compares the glacier to a mixture of ice and sand; and finally, in a more matured paper, falls back for an explanation upon the observations of agassiz regarding the capillaries of the glacier.[l] footnotes: [a] expressions such as "last summer," "last autumn," "recently," will be taken throughout in the sense which they had in the early half of , when this book was first published.--l. c. t. [b] 'memoir,' p. . [c] p. . [d] p. . [e] 'philosophical magazine,' . [f] 'memoir,' p. . [g] page . [h] page . [i] at page of the 'travels' the following passage also occurs:--"i believe that i may safely affirm that not one observation of the rate of motion of a glacier, either on the average or at any particular season of the year, existed when i commenced my experiments in ." [j] 'théorie,' p. . [k] 'occ. pap.,' p. . [l] in all that has been written upon glaciers in this country the above passages from the writings of rendu are unquoted; and many who mingled very warmly in the discussions of the subject were, until quite recently, ignorant of their existence. i was long in this condition myself, for i never supposed that passages which bear so directly upon a point so much discussed, and of such cardinal import, could have been overlooked; or that the task of calling attention to them should devolve upon myself nearly twenty years after their publication. now that they are discovered, i conceive no difference of opinion can exist as to the propriety of placing them in their true position. ( .) the measurements of agassiz and forbes completely verify the anticipations of rendu; but no writer with whom i am acquainted has added anything essential to the bishop's statements as to the identity of glacier and liquid motion. he laid down the conditions of the problem with perfect clearness, and, as regards the distribution of merit, the point to be decided is the relative importance of his idea, and of the measurements which were subsequently made. [sidenote: observations of forbes.] the observations on which professor forbes based the analogy between a glacier and a river are the following:--in he fixed four marks upon the mer de glace a little below the montanvert, the first of which was yards distant from the side of the glacier, while the last was at the centre "or a little beyond it." the relative velocity of these four points was found to be . . . . . the first observations were made upon two of these points, two others being subsequently added. professor forbes also determined the velocity of two points on the glacier du géant, and found the ratio of motion, in the first instance, to be as to . subsequent measurements, however, showed the ratio to be as to , the larger motion belonging to the station nearest to the centre of the glacier. these are the only measurements which i can find in his large work that establish the swifter motion of the centre of the glacier; and in these cases the velocity of the centre is compared with that of _one side_ only. in no instance that i am aware of, either in or subsequent years, did professor forbes extend his measurements quite across a glacier; and as regards completeness in this respect, no observations hitherto made can at all compare with those executed at the instance of agassiz upon the glacier of the aar. in professor forbes made a series of interesting experiments on a portion of the mer de glace near l'angle. he divided a length of feet into equal spaces, and fixed pins at the end of each. his theodolite was placed upon the ice, and in seventeen days he found that the ice feet nearer the centre than the theodolite had moved inches past the latter. these measurements were undertaken for a special object, and completely answered the end for which they were intended. in professor forbes made another important observation. fixing three stakes at the heights of , , and feet above the bed of the glacier, he found that in five days they moved respectively . , . , and . feet. the stake nearest the bed moved most slowly, thus showing that the ice is retarded by friction. this result was subsequently verified by the measurements of m. martins, and by my own. if we add to the above an observation made during a short visit to the aletsch glacier in , which showed its lateral retardation, i believe we have before us the whole of the measurements executed by professor forbes, which show the analogy between the motion of a glacier and that of a viscous body. [sidenote: measurements of agassiz.] illustrative of the same point, we have the elaborate and extensive series of measurements executed by m. wild under the direction of m. agassiz upon the glacier of the aar in , , , and , which exhibit on a grand scale, and in the most conclusive manner, the character of the motion of this glacier; and also show, on close examination, an analogy with fluid motion which neither m. agassiz nor professor forbes suspected. the former philosopher publishes a section in his 'système glaciaire,' entitled 'migrations of the centre;' in which he shows that the middle of the glacier is not always the point of swiftest motion. the detection of this fact demonstrates the attention devoted by m. agassiz to the discussion of his observations, but he gives no clue to the cause of the variation. on inspecting the shape of the valley through which the aar glacier moves, i find that these "migrations" follow the law established in upon the mer de glace, and enunciated at page . to sum up this part of the question:--the _idea_ of semi-fluid motion belongs entirely to rendu; the _proof_ of the quicker central flow belongs in part to rendu, but almost wholly to agassiz and forbes; the proof of the retardation of the bed belongs to forbes alone; while the discovery of the locus of the point of maximum motion belongs, i suppose, to me. forbes's theory. ( .) the formal statement of this theory is given in the following words:--"a glacier is an imperfect fluid, or viscous body, which is urged down slopes of a certain inclination by the mutual pressure of its parts." the consistency of the glacier is illustrated by reference to treacle, honey, and tar, and the theory thus enunciated and exemplified is called the 'viscous theory.' it has been the subject of much discussion, and great differences of opinion are still entertained regarding it. able and sincere men take opposite sides; and the extraordinary number of reviews which have appeared upon the subject during the last two years show the interest which the intellectual public of england take in the question. the chief differences of opinion turn upon the inquiry as to what professor forbes really meant when he propounded the viscous theory; some affirm one thing, some another, and, singularly enough, these differences continue, though the author of the theory has at various times published expositions of his views. [sidenote: "facts and principles."] the differences referred to arise from the circumstances that a sufficient distinction has not been observed between _facts_ and _principles_, and that the viscous theory has assumed various forms since its first promulgation. it has been stated to me that the theory of professor forbes is "the congeries of facts" which he has discovered. but it is quite evident that no recognition, however ample, of these facts would be altogether satisfactory to professor forbes himself. he claims recognition of his _theory_,[a] and no writer with whom i am acquainted makes such frequent use of the term. what then can the viscous theory mean apart from the facts? i interpret it as furnishing the principle from which the facts follow as physical consequences--that the glacier moves as a river because the ice is viscous. in this sense only can professor forbes's views be called a theory; in any other, his experiments are mere illustrations of the facts of glacier motion, which do not carry us a hair's breadth towards their physical cause. [sidenote: viscous theory;--what is it?] what then is the meaning of viscosity or viscidity? i have heard it defined by men of high culture as "gluey tenacity;" and such tenacity they once supposed a glacier to possess. if we dip a spoon into treacle, honey, or tar, we can draw the substance out into filaments, and the same may be done with melted caoutchouc or lava. all these substances are viscous, and all of them have been chosen to illustrate the physical property in virtue of which a glacier moves. viscosity then consists in the power of being drawn out when subjected to a force of tension, the substance, after stretching, being in a state of molecular equilibrium, or, in other words, devoid of that elasticity which would restore it to its original form. this certainly was the idea attached to professor forbes's words by some of his most strenuous supporters, and also by eminent men who have never taken part in any controversy on the subject. mr. darwin, for example, speaks of felspathic rocks being "stretched" while flowing slowly onwards in a pasty condition, in precisely the same manner as professor forbes believes that the ice of moving glaciers is stretched and fissured; and professor forbes himself quotes these words of mr. darwin as illustrative of his theory.[b] the question now before us is,--does a glacier exhibit that power of yielding to a force of tension which would entitle its ice to be regarded as a viscous substance? [sidenote: theory tested.] with a view to the solution of this question mr. hirst took for me the inclinations of the mer de glace and all its tributaries in ; the effect of a change of inclination being always noted. i will select from those measurements a few which bear more specially upon the subject now under consideration, commencing with the glacier des bois, down which the ice moves in that state of wild dislocation already described. the inclination of the glacier above this cascade is ° ', and that of the cascade itself is ° ', the change of inclination being therefore ° '. [illustration: fig. . inclinations of ice cascasde of the glacier des bois.] in fig. i have protracted the inclination of the cascade and of the glacier above it; the line a b representing the former and b c the latter. now a stream of molten lava, of treacle, or tar, would, in virtue of its viscosity, be able to flow over the brow at b without breaking across; but this is not the case with the glacier; it is so smashed and riven in crossing this brow, that, to use the words of professor forbes himself, "it pours into the valley beneath in a cascade of icy fragments." [sidenote: inclinations of the mer de glace.] but this reasoning will appear much stronger when we revert to other slopes upon the mer de glace. for example, its inclination above l'angle is °, and it afterwards descends a slope of ° ', the change of inclination being ° '. if we protract these inclinations to scale, we have the line a b, fig. , representing the steeper slope, and b c that of the glacier above it. one would surely think that a viscous body could cross the brow b without transverse fracture, but this the glacier cannot do, and professor forbes himself pronounces this portion of the mer de glace impassable. indeed it was the profound crevasses here formed which placed me in a difficulty already referred to. higher up again, the glacier is broken on passing from a slope of ° ' to one of °. such observations show how differently constituted a glacier is from a stream of lava in a "pasty condition," or of treacle, honey, tar, or melted caoutchouc, to all which it has been compared. in the next section i shall endeavour to explain the origin of the crevasses, and shall afterwards make a few additional remarks on the alleged viscosity of ice. [illustration: fig. . inclinations of mer de glace above l'angle.] footnotes: [a] "mr. hopkins," writes professor forbes, "has done me the honour, in the memoirs before alluded to, to mention with approbation my observations and experiments on the subject of glaciers. he has been more sparing either in praise or criticism of the theory which i have founded upon them. had mr. hopkins," &c.--_eighth letter_; 'occ. papers,' p. . [b] 'occ. papers,' p. . the crevasses. ( .) [sidenote: crevasses caused by the motion.] having made ourselves acquainted with the motion of the glacier, we are prepared to examine those rents, fissures, chasms, or, as they are most usually called, _crevasses_, by which all glaciers are more or less intersected. they result from the motion of the glacier, and the laws of their formation are deduced immediately from those of the motion. the crevasses are sometimes very deep and numerous, and apparently without law or order in their distribution. they cut the ice into long ridges, and break these ridges transversely into prisms; these prisms gradually waste away, assuming, according to the accidents of their melting, the most fantastic forms. i have seen them like the mutilated statuary of an ancient temple, like the crescent moon, like huge birds with outstretched wings, like the claws of lobsters, and like antlered deer. such fantastic sculpture is often to be found on the ice cascades, where the riven glacier has piled vast blocks on vaster pedestals, and presented them to the wasting action of sun and air. in fig. i have given a sketch of a mass of ice of this character, which stood in on the dislocated slope of the glacier des bois. [sidenote: fantastic ice-masses.] [illustration: fig. . fantastic mass of ice.] it is usual for visitors to the montanvert to descend to the glacier, and to be led by their guides to the edges of the crevasses, where, being firmly held, they look down into them; but those who have only made their acquaintance in this way know but little of their magnitude and beauty in the more disturbed portions of glaciers. as might be expected, they have been the graves of many a mountaineer; and the skeletons found upon the glacier prove that even the chamois itself, with its elastic muscles and admirable sureness of foot, is not always safe among the crevasses. they are grandest in the higher ice-regions, where the snow hangs like a coping over their edges, and the water trickling from these into the gloom forms splendid icicles. the görner glacier, as we ascend it towards the old weissthor, presents many fine examples of such crevasses; the ice being often torn in a most curious and irregular manner. you enter a porch, pillared by icicles, and look into a cavern in the very body of the glacier, encumbered with vast frozen bosses which are fringed all round by dependent icicles. at the peril of your life from slipping, or from the yielding of the stalactites, you may enter these caverns, and find yourself steeped in the blue illumination of the place. their beauty is beyond description; but you cannot deliver yourself up, heart and soul, to its enjoyment. there is a strangeness about the place which repels you, and not without anxiety do you look from your ledge into the darkness below, through which the sound of subglacial water sometimes rises like the tolling of distant bells. you feel that, however the cold splendours of the place might suit a purely spiritual essence, they are not congenial to flesh and blood, and you gladly escape from its magnificence to the sunshine of the world above. [sidenote: birth of a crevasse.] from their numbers it might be inferred that the formation of crevasses is a thing of frequent occurrence and easy to observe; but in reality it is very rarely observed. simond was a man of considerable experience upon the ice, but the first crevasse he ever saw formed was during the setting out of one of our lines, when a narrow rent opened beneath his feet, and propagated itself through the ice with loud cracking for a distance of or yards. crevasses always commence in this way as mere narrow cracks, which open very slowly afterwards. i will here describe the only case of crevasse-forming which has come under my direct observation. on the st of july, , mr. hirst and myself, having completed our day's work, were standing together upon the glacier du géant, when a loud dull sound, like that produced by a heavy blow, seemed to issue from the body of the ice underneath the spot on which we stood. this was succeeded by a series of sharp reports, which were heard sometimes above us, sometimes below us, sometimes apparently close under our feet, the intervals between the louder reports being filled by a low singing noise. we turned hither and thither as the direction of the sounds varied; for the glacier was evidently breaking beneath our feet, though we could discern no trace of rupture. for an hour the sounds continued without our being able to discover their source; this at length revealed itself by a rush of air-bubbles from one of the little pools upon the surface of the glacier, which was intersected by the newly-formed crevasse. we then traced it for some distance up and down, but hardly at any place was it sufficiently wide to permit the blade of my penknife to enter it. m. agassiz has given an animated description of the terror of his guides upon a similar occasion, and there was an element of awe in our own feelings as we heard the evening stillness of the glacier thus disturbed. [sidenote: mechanical origin.] with regard to the mechanical origin of the crevasses the most vague and untenable notions had been entertained until mr. hopkins published his extremely valuable papers. to him, indeed, we are almost wholly indebted for our present knowledge of the subject, my own experiments upon this portion of the glacier-question being for the most part illustrations of the truth of his reasoning. to understand the fissures in their more complex aspects it is necessary that we should commence with their elements. i shall deal with the question in my own way, adhering, however, to the mechanical principles upon which mr. hopkins has based his exposition. [illustration: fig. . diagram explanatory of the mechanical origin of crevasses.] let a b, c d, be the bounding sides of a glacier moving in the direction of the arrow; let _m_, _n_ be two points upon the ice, one, _m_, close to the retarding side of the valley, and the other, _n_, at some distance from it. after a certain time, the point _m_ will have moved downwards to _m'_, but in consequence of the swifter movement of the parts at a distance from the sides, _n_ will have moved in the same time to _n'_. thus the line _m n_, instead of being at right angles to the glacier, takes up the oblique position _m' n'_; but to reach from _m'_ to _n'_ the line _m n_ would have to stretch itself considerably; every other line that we can draw upon the ice parallel to _m' n'_ is in a similar state of tension; or, in other words, the sides of the glacier are acted upon by an oblique pull towards the centre. now, mr. hopkins has shown that the direction in which this oblique pull is strongest encloses an angle of ° with the side of the glacier. [sidenote: line of greatest strain.] [illustration: fig. . diagram showing the line of greatest strain.] what is the consequence of this? let a b, c d, fig. , represent, as before, the sides of the glacier, moving in the direction of the arrow; let the shading lines enclose an angle of ° with the sides. _along_ these lines the marginal ice suffers the greatest strain, and, consequently _across_ these lines and at right angles to them, the ice tends to break and to form _marginal crevasses_. the lines, _o p_, _o p_, mark the direction of these crevasses; they are at right angles to the line of greatest strain, and hence also enclose an angle of ° with the side of the valley, _being obliquely pointed upwards_. [sidenote: marginal and transverse crevasses.] this latter result is noteworthy; it follows from the mechanical data that the swifter motion of the centre tends to produce marginal crevasses which are inclined from the side of the glacier towards its source, and not towards its lower extremity. but when we look down upon a glacier thus crevassed, the first impression is that the sides have been dragged down, and have left the central portions behind them; indeed, it was this very appearance that led m. de charpentier and m. agassiz into the error of supposing that the sides of a glacier moved more quickly than its middle portions; and it was also the delusive aspect of the crevasses which led professor forbes to infer the slower motion of the eastern side of the mer de glace. the retardation of the ice is most evident near the sides; in most cases, the ice for a considerable distance right and left of the central line moves with a sensibly uniform velocity; there is no dragging of the particles asunder by a difference of motion, and, consequently, a compact centre is perfectly compatible with fissured sides. nothing is more common than to see a glacier with its sides deeply cut, and its central portions compact; this, indeed, is always the case where the glacier moves down a bed of uniform inclination. but supposing that the bed is not uniform--that the valley through which the glacier moves changes its inclination abruptly, so as to compel the ice to pass over a brow; the glacier is then circumstanced like a stick which we try to break by holding its two ends and pressing it against the knee. the brow, where the bed changes its inclination, represents the knee in the case of the stick, while the weight of the glacier itself is the force that tends to break it. it breaks; and fissures are formed across the glacier, which are hence called _transverse crevasses_. [sidenote: grindelwald glacier.] no glacier with which i am acquainted illustrates the mechanical laws just developed more clearly and fully than the lower glacier of grindelwald. proceeding along the ordinary track beside the glacier, at about an hour's distance from the village the traveller reaches a point whence a view of the glacier is obtained from the heights above it. the marginal fissures are very cleanly cut, and point nearly in the direction already indicated; the glacier also changes its inclination several times along the distance within the observer's view. on crossing each brow the glacier is broken across, and a series of transverse crevasses is formed, which follow each other down the slope. at the bottom of the slope tension gives place to pressure, the walls of the crevasses are squeezed together, and the chasms closed up. they remain closed along the comparatively level space which stretches between the base of one slope and the brow of the next; but here the glacier is again transversely broken, and continues so until the base of the second slope is reached, where longitudinal pressure instead of longitudinal strain begins to act, and the fissures are closed as before. in fig. a i have given a sketchy section of a portion of the glacier, illustrating the formation of the crevasses at the top of a slope, and their subsequent obliteration at its base. [sidenote: compression and tension.] [illustration: fig. a, b. section and plan of a portion of the lower grindelwald glacier.] another effect is here beautifully shown, namely, the union of the transverse and marginal crevasses to form continuous fissures which stretch quite across the glacier. fig. b will illustrate my meaning, though very imperfectly; it represents a plan of a portion of the lower grindelwald glacier, with both marginal and transverse fissures drawn upon it. i have placed it under the section so that each part of it may show in plan the portion of the glacier which is shown in section immediately above it. it shows how the marginal crevasses remain after the compression of the centre has obliterated the transverse ones; and how the latter join on to the former, so as to form continuous fissures, which sweep across the glacier in vast curves, with their convexities turned upwards. the illusion before referred to is here strengthened; the crevasses turn, so to say, _against_ the direction of motion, instead of forming loops, with their convexities pointing downwards, and thus would impress a person unacquainted with the mechanical data with the idea that the glacier margins moved more quickly than the centre. the figures are intended to convey the idea merely; on the actual slopes of the glacier between twenty and thirty chasms may be counted: also the word "compression" ought to have been limited to the level portions of the sketch. [sidenote: longitudinal crevasses.] besides the two classes of fissures mentioned we often find others, which are neither marginal nor transverse. the terminal portions of many glaciers, for example, are in a state of compression; the snout of the glacier abuts against the ground, and having to bear the thrust of the mass behind it, if it have room to expand laterally, the ice will yield, and _longitudinal crevasses_ will be formed. they are of very common occurrence, but the finest example of the kind is perhaps exhibited by the glacier of the rhone. after escaping from the steep gorge which holds the cascade, this glacier encounters the bottom of a comparatively wide and level valley; the resistance to its forward motion is augmented, while its ability to expand laterally is increased; it has to bear a longitudinal thrust, and it splits at right angles to the pressure [strain?]. a series of fissures is thus formed, the central ones of which are truly longitudinal; but on each side of the central line the crevasses diverge, and exhibit a fan-like arrangement. this disposition of the fissures is beautifully seen from the summit of the mayenwand on the grimsel pass. [illustration: fig. . diagram illustrating the crevassing of convex sides of glacier.] here then we have the elements, so to speak, of glacier-crevassing, and through their separate or combined action the most fantastic cutting up of a glacier may be effected. and see how beautifully these simple principles enable us to account for the remarkable crevassing of the eastern side of the mer de glace. let a b, c d, be the opposite sides of a portion of the glacier, near the montanvert; c d being east, and a b west, the glacier moving in the direction of the arrow; let the points _m n_ represent the extremities of our line of stakes, and let us suppose an elastic string stretched across the glacier from one to the other. we have proved that the point of maximum motion here lies much nearer to the side c d than to a b. let _o_ be this point, and, seizing the string at _o_, let it be drawn in the direction of motion until it assumes the position, _m_, _o'_, _n_. it is quite evident that _o' n_ is in a state greater tension than _o' m_, and the ice at the eastern side of the mer de glace is in a precisely similar mechanical condition. it suffers a greater strain than the ice at the opposite side of the valley, and hence is more fissured and broken. thus we see that the crevassing of the eastern side of the glacier is a simple consequence of the quicker motion of that side, and does not, as hitherto supposed, demonstrate its slower motion. the reason why the eastern side of the glacier, as a whole, is much more fissured than the western side is, that there are two long segments which turn their convex curvature eastward, and only one segment of the glacier which turns its convexity westward. [sidenote: crevassing of convex side.] the lower portion of the rhone glacier sweeps round the side of the valley next the furca, and turns throughout a convex curve to this side: the crevasses here are wide and frequent, while they are almost totally absent at the opposite side of the glacier. the lower grindelwald glacier turns at one place a convex curve towards the eiger, and is much more fissured at that side than at the opposite one; indeed, the fantastic ice-splinters, columns, and minarets, which are so finely exhibited upon this glacier, are mainly due to the deep crevassing of the convex side. numerous other illustrations of the law might, i doubt not, be discovered, and it would be a pleasant and useful occupation to one who takes an interest in the subject, to determine, by strict measurements upon other glaciers, the locus of the point of maximum motion, and to observe the associated mechanical effects. [sidenote: bergschrunds.] the appearance of crevasses is often determined by circumstances more local and limited than those above indicated; a boss of rock, a protuberance on the side of the flanking mountain, anything, in short, which checks the motion of one part of the ice and permits an adjacent portion to be pushed away from it, produces crevasses. some valleys are terminated by a kind of mountain-circus with steep sides, against which the snow rises to a considerable height. as the mass is urged downwards, the lower portion of the snow-slope is often torn away from its higher portion, and a chasm is formed, which usually extends round the head of the valley. to such a crevasse the specific name _bergschrund_ is applied in the bernese alps; i have referred to one of them in the account of the "passage of the strahleck." ( .) the phenomena described and accounted for in the last chapter have a direct bearing upon the question of viscosity. in virtue of the quicker central flow the lateral ice is subject to an oblique strain; but, instead of stretching, it breaks, and marginal crevasses are formed. we also see that a slight curvature in the valley, by throwing an additional strain upon one half of the glacier, produces an augmented crevassing of that side. but it is known that a substance confessedly viscous may be broken by a sudden shock or strain. professor forbes justly observes that sealing-wax at moderate temperatures will mould itself (with time) to the most delicate inequalities of the surface on which it rests, but may at the same time be shivered to atoms by the blow of a hammer. hence, in order to estimate the weight of the objection that a glacier breaks when subjected to strain, we must know the conditions under which the force is applied. the mer de glace has been shown (p. ) to move through the neck of the valley at trélaporte at the rate of twenty inches a day. let the sides of this page represent the boundaries of the glacier at trélaporte, and any one of its lines of print a transverse slice of ice. supposing the line to move down the page as the slice of ice moves down the valley, then the bending of the ice in twenty-four hours, shown on such a scale, would only be sufficient to push forward the centre in advance of the sides by a very small fraction of the width of the line of print. to such an extremely gradual strain the ice is unable to accommodate itself without fracture. [sidenote: numerical test of viscosity.] or, referring to actual numbers:--the stake no. on our th line, page , stood on the lateral moraine of the mer de glace; and between it and no. a distance of feet intervened. let a b, fig. , be the side of the glacier, moving in the direction of the arrow, and let _a b c d_ be a square upon the glacier with a side of feet. the whole square moves with the ice, but the side _b d_ moves quickest; the point _a_ moving inches, while _b_ moves . inches in hours; the differential motion therefore amounts to an inch in five hours. let _a b' d' c_ be the shape of the figure after five hours' motion; then the line _a b_ would be extended to _a b'_ and _c d_ to _c d'_. [illustration: fig. . diagram illustrating test of viscosity.] the extension of _these_ lines does not however express the _maximum_ strain to which the ice is subjected. mr. hopkins has shown that this takes place along the line _a d_; in five hours then this line, if capable of stretching, would be stretched to _a d'_. from the data given every boy who has mastered the th proposition of the first book of euclid can find the length both of _a d_ and _a d'_; the former is . inches, and the latter is . , the difference between them being seven-tenths of an inch. this is the amount of yielding required from the ice in five hours, but it cannot grant this; the glacier breaks, and numerous marginal crevasses are formed. it must not be forgotten that the evidence here adduced merely shows what ice cannot do; what it _can_ do in the way of viscous yielding we do not know: there exists as yet no single experiment on great masses or small to show that ice possesses in any sensible degree that power of being drawn out which seems to be the very essence of viscosity. i have already stated that the crevasses, on their first formation, are exceedingly narrow rents, which widen very slowly. the new crevasse observed by our guide required several days to attain a width of three inches; while that observed by mr. hirst and myself did not widen a single inch in three days. this, i believe, is the general character of the crevasses; they form suddenly and open slowly. both facts are at variance with the idea that ice is viscous; for were this substance capable of stretching at the slow rate at which the fissures widen, there would be no necessity for their formation. [sidenote: stretching of ice not proved.] it cannot be too clearly and emphatically stated that the _proved_ fact of a glacier conforming to the law of semi-fluid motion is a thing totally different from the _alleged_ fact of its being viscous. nobody since its first enunciation disputed the former. i had no doubt of it when i repaired to the glaciers in ; and none of the eminent men who have discussed this question with professor forbes have thrown any doubt upon his measurements. it is the assertion that small pieces of ice are proved to be viscous[a] by the experiments made upon glaciers, and the consequent impression left upon the public mind--that ice possesses the "gluey tenacity" which the term viscous suggests--to which these observations are meant to apply. footnotes: [a] "the viscosity, though it cannot be traced in the parts _if very minute_ nevertheless _exists_ there, as unequivocally proved by experiments on the large scale."--forbes in 'phil. mag.,' vol. x., p. . heat and work. ( .) [sidenote: connexion of natural forces.] great scientific principles, though usually announced by individuals, are often merely the distinct expression of thoughts and convictions which had long been entertained by all advanced investigators. thus the more profound philosophic thinkers had long suspected a certain equivalence and connexion between the various forces of nature; experiment had shown the direct connexion and mutual convertibility of many of them, and the spiritual insight, which, in the case of the true experimenter, always surrounds and often precedes the work of his hands, revealed more or less plainly that natural forces either had a common root, or that they formed a circle, whose links were so connected that by starting from any one of them we could go through the circuit, and arrive at the point from which we set out. for the last eighteen years this subject has occupied the attention of some of the ablest natural philosophers, both in this country and on the continent. the connexion, however, which has most occupied their minds is that between _heat_ and _work_; the absolute numerical equivalence of the two having, i believe, been first announced by a german physician named mayer, and experimentally proved in this country by mr. joule. [sidenote: mechanical equivalent of heat.] a lead bullet may be made hot enough to burn the hand, by striking it with a hammer, or by rubbing it against a board; a clever blacksmith can make a nail red-hot by hammering it; count rumford boiled water by the heat developed in the boring of cannon, and inferred from the experiment that heat was not what it was generally supposed to be, an imponderable fluid, but a kind of motion generated by the friction. now mr. joule's experiments enable us to state the exact amount of heat which a definite expenditure of mechanical force can originate. i say _originate_, not drag from any hiding-place in which it had concealed itself, but actually bring into existence, so that the total amount of heat in the universe is thereby augmented. if a mass of iron fall from a tower feet in height, we can state the precise amount of heat developed by its collision with the earth. supposing all the heat thus generated to be concentrated in the iron itself, its temperature would thereby be raised nearly ° fahr. gravity in this case has expended a certain amount of force in pulling the iron to the earth, and this force is the _mechanical equivalent_ of the heat generated. furthermore, if we had a machine so perfect as to enable us to apply all the heat thus produced to the raising of a weight, we should be able, by it, to lift the mass of iron to the precise point from which it fell. but the heat cannot lift the weight and still continue heat; this is the peculiarity of the modern view of the matter. the heat is consumed, used up, it is no longer heat; but instead of it we have a certain amount of gravitating force stored up, which is ready to act again, and to regenerate the heat when the weight is let loose. in fact, when the falling weight is stopped by the earth, the motion of its mass is converted into a motion of its molecules; when the weight is lifted by heat, molecular motion is converted into ordinary mechanical motion, but for every portion of either of them brought into existence an equivalent portion of the other must be consumed. what is true for masses is also true for atoms. as the earth and the piece of iron mutually attract each other, and produce heat by their collision, so the carbon of a burning candle and the oxygen of the surrounding air mutually attract each other; they rush together, and on collision the arrested motion becomes heat. in the former case we have the conversion of gravity into heat, in the latter the conversion of chemical affinity into heat; but in each case the process consists in the generation of motion by attraction, and the subsequent change of that motion into motion of another kind. mechanically considered, the attraction of the atoms and its results is precisely the same as the attraction of the earth and weight and _its_ results. [sidenote: heat produced if the earth struck the sun.] but what is true for an atom is also true for a planet or a sun. supposing our earth to be brought to rest in her orbit by a sudden shock, we are able to state the exact amount of heat which would be thereby generated. the consequence of the earth's being thus brought to rest would be that it would fall into the sun, and the amount of heat which would be generated by this second collision is also calculable. helmholtz has calculated that in the former case the heat generated would be equal to that produced by the combustion of fourteen earths of solid coal, and in the latter case the amount would be times greater. [sidenote: shifting of atoms.] whenever a weight is lifted by a steam-engine in opposition to the force of gravity an amount of heat is consumed equivalent to the work done; and whenever the molecules of a body are shifted in opposition to their mutual attractions work is also performed, and an equivalent amount of heat is consumed. indeed the amount of work done in the shifting of the molecules of a body by heat, when expressed in ordinary mechanical work, is perfectly enormous. the lifting of a heavy weight to the height of feet may be as nothing compared with the shifting of the atoms of a body by an amount so small that our finest means of measurement hardly enable us to determine it. different bodies give heat different degrees of trouble, if i may use the term, in shifting their atoms and putting them in new places. iron gives more trouble than lead; and water gives far more trouble than either. the heat expended in this molecular work is lost as heat; it does not show itself as temperature. suppose the heat produced by the combustion of an ounce of candle to be concentrated in a pound of iron, a certain portion of that heat would go to perform the molecular work to which i have referred, and the remainder would be expended in raising the temperature of the body; and if the same amount of heat were communicated to a pound of iron and to a pound of lead, the balance in favour of temperature would be greater in the latter case than in the former, because the heat would have less molecular work to do; the lead would become more heated than the iron. to raise a pound of iron a certain number of degrees in temperature would, in fact, require more than three times the absolute quantity of heat which would be required to raise a pound of lead the same number of degrees. conversely, if we place the pound of iron and the pound of lead, heated to the same temperature, into ice, we shall find that the quantity of ice melted by the iron will be more than three times that melted by the lead. in fact, the greater amount of molecular work invested in the iron now comes into play, the atoms again obey their own powerful forces, and an amount of heat corresponding to the energy of these forces is generated. this molecular work is that which has usually been called _specific heat_, or _capacity for heat_. according to the _materialistic_ view of heat, bodies are figured as sponges, and heat as a kind of fluid absorbed by them, different bodies possessing different powers of absorption. according to the _dynamic_ view, as already explained, heat is regarded as a motion, and capacity for heat indicates the quantity of that motion consumed in internal changes. the greatest of these changes occurs when a body passes from one state of aggregation to another, from the solid to the liquid, or from the liquid to the aëriform state; and the quantity of heat required for such changes is often enormous. to convert a pound of ice at ° fahr. into water _at the same temperature_ would require an amount of heat competent, if applied as mechanical force, to lift the same pound of ice to a height of , feet; it would raise a ton of ice nearly feet, or it would lift between and tons to a height of one foot above the earth's surface. to convert a pound of water at ° into a pound of steam at the same temperature would require an amount of heat which would perform nearly seven times the amount of mechanical work just mentioned. [sidenote: heat consumed in molecular work.] this heat is entirely expended in _interior work_,[a] and does nothing towards augmenting the temperature; the water is at the temperature of the ice which produced it, both are °; and the steam is at the temperature of the water which produced it, both are °. the whole of the heat is consumed in producing the change of aggregation; i say "_consumed_," not hidden or "latent" in either the water or the steam, but absolutely non-existent as heat. the molecular forces, however, which the heat has sacrificed itself to overcome are able to reproduce it; the water in freezing and the steam in condensing give out the exact amount of heat which they consumed when the change of aggregation was in the opposite direction. at a temperature of several degrees below its freezing point ice is much harder than at °. i have more than once cooled a sphere of the substance in a bath of solid carbonic acid and ether to a temperature of ° below the freezing point. during the time of cooling the ice crackled audibly from its contraction, and afterwards it quite resisted the edge of a knife; while at ° it may be cut or crushed with extreme facility. the cold sphere was subjected to pressure; it broke with the detonation of a vitreous body, and was taken from the press a white opaque powder; which, on being subsequently raised to ° and again compressed, was converted into a pellucid slab of ice. [sidenote: ice near the melting point.] but before the temperature of ° is quite attained, ice gives evidence of a loosening of its crystalline texture. indeed the unsoundness of ice at and near its melting point has been long known. sir john leslie, for example, states that ice at ° is _friable_; and every skater knows how rotten ice becomes before it thaws. m. person has further shown that the latent heat of ice, that is to say, the quantity of heat necessary for its liquefaction, is not quite expressed by the quantity consumed in reducing ice at ° to the liquid state. the heat begins to be rendered latent, or in other words the change of aggregation commences, a little before the substance reaches °,--a conclusion which is illustrated and confirmed by the deportment of melting ice under pressure. [sidenote: rotten ice and softened wax.] in reference to the above result professor forbes writes as follows:--"i have now to refer to a fact ... established by a french experimenter, m. person, who appears not to have had even remotely in his mind the theory of glaciers, when he announced the following facts, viz.--'that ice does not pass abruptly from the solid to the fluid state; that it begins to _soften_ at a temperature of ° centigrade below its thawing point; that, consequently, between ° ' and ° of fahr. ice is actually passing through various degrees of plasticity within narrower limits, but in the same manner that wax, for example, softens before it melts.'" the "_softening_" here referred to is the "friability," of sir j. leslie, and what i have called a "loosening of the texture." let us suppose the serpentine covered by a sheet of pitch so smooth and hard as to enable a skater to glide over it; and which is afterwards gradually warmed until it begins to bend under his weight, and finally lets him through. a comparison of this deportment with that of a sheet of ice under the same circumstances enables us to decide whether ice "passes through various degrees of plasticity in the same manner as wax softens before it melts." m. person concerned himself solely with the heat absorbed, and no doubt in both wax and ice that heat is expended in "interior work." in the one case, however, the body is so constituted that the absorbed heat is expended in rendering the substance viscous; and the question simply is, whether the heat absorbed by the ice gives its molecules a freedom of play which would entitle it also to be called viscous; whether, in short, "rotten ice" and softened wax present the same physical qualities? footnotes: [a] i borrow this term from professor clausius's excellent papers on the dynamical theory of heat. ( .) there is one other point in connexion with the viscous theory which claims our attention. the announcement of that theory startled scientific men, and for two or three years after its first publication it formed the subject of keen discussion. this finally subsided, and afterwards professor forbes drew up an elaborate paper, which was presented in three parts to the royal society in and , and subsequently published in the 'philosophical transactions.' in the concluding portion of part iii. professor forbes states and answers the question, "how far a glacier is to be regarded as a plastic mass?" in these words:--"were a glacier composed of a solid crystalline cake of ice, fitted or moulded to the mountain bed which it occupies, like a lake tranquilly frozen, it would seem impossible to admit such a flexibility or yielding of parts as should permit any comparison to a fluid or semifluid body, transmitting pressure horizontally, and whose parts might change their mutual positions so that one part should be pushed out whilst another remained behind. but we know, in point of fact, that a glacier is a body very differently constituted. it is clearly proved by the experiments of agassiz and others that the glacier is not a mass of ice, but of ice and water, the latter percolating freely through the crevices of the former to all depths of the glacier; and it is a matter of ocular demonstration that these crevices, though very minute, communicate freely with one another to great distances; the water with which they are filled communicates force also to great distances, and exercises a tremendous hydrostatic pressure to move onwards in the direction in which gravity urges it, the vast porous mass of seemingly rigid ice in which it is as it were bound up." [sidenote: capillary hypothesis.] "now the water in the crevices," continues professor forbes, "does not constitute the glacier, but only the principal vehicle of the force which acts on it, and the slow irresistible energy with which the icy mass moves onwards from hour to hour with a continuous march, bespeaks of itself the presence of a fluid pressure. but if the ice were not in some degree ductile or plastic, this pressure could never produce any the least forward motion of the mass. the pressure in the capillaries of the glacier can only tend to separate one particle from another, and thus produce tensions and compressions _within the body of the glacier itself_, which yields, owing to its slightly ductile nature, in the direction of least resistance, retaining its continuity, or recovering it by reattachment after its parts have suffered a bruise, according to the violence of the action to which it has been exposed." i will not pretend to say that i fully understand this passage, but, taking it and the former one together, i think it is clear that the water which is supposed to gorge the capillaries of the glacier is assumed to be essential to its motion. indeed, an extreme degree of sensitiveness has been ascribed to the glacier as regards the changes of temperature by which the capillaries are affected. in three succeeding days, for example, professor forbes found the diurnal summer motion of a point upon the mer de glace to increase from . to . inches a day; a result which he says he is "persuaded" to be due to the increasing heat of the weather at the time. if, then, the glacier capillaries can be gorged so quickly as this experiment would indicate, it is fair to assume that they are emptied with corresponding speed when the supply is cut away. [sidenote: temperature at chamouni; winter .] the extraordinary coldness of the weather previous to the christmas of is in the recollection of everybody: this lowness of temperature also extended to the mer de glace and its environs. i had last summer left with auguste balmat and the abbé vueillet thermometers with which observations were made daily during the cold weather referred to. i take the following from balmat's register. minimum date. temperature centigrade. december - ° " - " - - / " - " - " - - / " - - / december - - / ° " - - / " - " + " - " - - / " - the temperature at the montanvert during the above period may be assumed as generally some degrees lower, so that for a considerable period, previous to my winter observations, the portion of the mer de glace near the montanvert had been exposed to a very low temperature. i reached the place after the weather had become warm, but during my stay there the maximum temperature did not exceed - - / ° c. considering therefore the long drain to which the glacier had been subjected previous to the th of december, it is not unreasonable to infer that the capillary supply assumed by professor forbes must by that time have been exhausted. notwithstanding this, the motion of the glacier at the montanvert amounted at the end of december to half its maximum summer motion. [sidenote: balmat's measurements.] the observations of balmat which have been published by professor forbes[a] also militate, as far as they go, against the idea of proportionality between the capillary supply and the motion. if the temperatures recorded apply to the mer de glace during the periods of observation, it would follow that from the th of december to the th of april the temperature of the air was constantly under zero centigrade, and hence, during this time, the gorging of the capillaries, which is due to superficial melting, must have ceased. still, throughout this entire period of depletion the motion of the glacier steadily increased from twenty-four inches to thirty-four and a half inches a day. what has been here said of the montanvert, and of the points lower down where balmat's measurements were made, of course applies with greater force to the higher portions of the glacier, which are withdrawn from the operation of superficial melting for a longer period, and which, nevertheless, if i understand professor forbes aright, have their motion _least affected_ in winter. he records, for example, an observation of mr. bakewell's, by which the glacier des bossons is shown to be stationary at its end, while its upper portions are moving at the rate of a foot a day. this surely indicates that, at those places where the glacier is longest cut off from superficial supply, the motion is least reduced, which would be a most strange result if the motion depended, as affirmed, upon the gorging of the capillaries. [sidenote: bakewell's observations.] the perusal of the conclusion of professor forbes's last volume shows me that a thought similar to that expressed above occurred to mr. bakewell also. speaking of a shallow glacier which moved when the alleged temperature was so enormously below the freezing point that professor forbes regards the observation as open to question (in which i agree with him), mr. bakewell asks, "is it possible that infiltrated water can have any action whatever under such circumstances?" the reply of professor forbes contains these words:--"i have nowhere affirmed the presence of liquid water to be a _sine quâ non_ to the plastic motion of glaciers." this statement, i confess, took me by surprise, which was not diminished by further reading. speaking of the influence of temperature on the motion of the mer de glace, professor forbes says, the glacier "took no real start until the frost had given way, and the tumultuous course of the arveiron showed that its veins were again filled with the circulating medium to which the glacier, like the organic frame, owes its moving energy."[b] and again:--"it is this fragility precisely which, yielding to the hydrostatic pressure of the unfrozen water contained in the countless capillaries of the glacier, produces the crushing action which shoves the ice over its neighbour particles."[c] [sidenote: huxley's observations.] after the perusal of the foregoing paragraphs the reader will probably be less interested in the question as to whether the assumed capillaries exist at all in the glacier. according to mr. huxley's observations, they do not.[d] during the summer of he carefully experimented with coloured liquids on the mer de glace and its tributaries, and in no case was he able to discover these fissures in the sound unweathered ice. i have myself seen the red liquid resting in an auger-hole, where it had lain for an hour without diffusing itself in any sensible degree. this cavity intersected both the white ice and the blue veins of the glacier; and mr. huxley, in my presence, cut away the ice until the walls of the cavity became extremely thin, still no trace of liquid passed through them. experiments were also made upon the higher portions of the mer de glace, and also on the glacier du géant, with the same result. thus the very existence of these capillaries is rendered so questionable, that no theory of glacier-motion which invokes their aid could be considered satisfactory. footnotes: [a] 'occ. pap.,' p. . [b] 'phil. trans.,' , p. , and 'occ. pap.,' p. . [c] 'occ. pap.,' p. . [d] 'phil. mag.,' , vol. xiv., p. . thomson's theory. ( .) in the 'transactions' of the royal society of edinburgh for is published a very interesting paper by prof. james thomson of queen's college, belfast, wherein he deduces, as a consequence of a principle announced by the french philosopher carnot, that water, when subjected to pressure, requires a greater cold to freeze it than when the pressure is removed. he inferred that the lowering of the freezing point for every atmosphere of pressure amounted to . of a degree centigrade. this deduction was afterwards submitted to the test of experiment by his distinguished brother prof. wm. thomson, and proved correct. on the fact thus established is founded mr. james thomson's theory of the "plasticity of ice as manifested in glaciers." [sidenote: statement of theory.] the theory is this:--certain portions of the glacier are supposed first to be subjected to pressure. this pressure liquefies the ice, the water thus produced being squeezed through the glacier in the direction in which it can most easily escape. but cold has been evolved by the act of liquefaction, and, when the water has been relieved from the pressure, it freezes in a new position. the pressure being thus abolished at the place where it was first applied, new portions of the ice are subjected to the force; these in their turn liquefy, the water is dispersed as before, and re-frozen in some other place. to the succession of processes here assumed mr. thomson ascribes the changes of form observed in glaciers. this theory was first communicated to the royal society through the author's brother, prof. william thomson, and is printed in the 'proceedings' of the society for may, . it was afterwards communicated to the british association in dublin, in whose 'reports' it is further published; and again it was communicated to the belfast literary and philosophical society, in whose 'proceedings' it also finds a place. on the th of november, , mr. james thomson communicated to the royal society, through his brother, a second paper, in which he again draws attention to his theory. he offers it in substitution for my views as the best argument that he can adduce against them; he also controverts the explanations of regelation propounded by prof. james d. forbes and prof. faraday, believing that his own theory explains all the facts so well as to leave room for no other. [sidenote: difficulties of theory.] but the passage in this paper which demands my chief attention is the following:--"prof. tyndall (writes mr. thomson), in papers and lectures subsequent to the publication of this theory, appears to adopt it to some extent, and to endeavour to make its principles co-operate with the views he had previously founded on mr. faraday's fact of regelation." i may say that mr. thomson's main thought was familiar to me long before his first communication on the plasticity of ice appeared; but it had little influence upon my convictions. were the above passage correct, i should deserve censure for neglecting to express my obligations far more explicitly than i have hitherto done; but i confess that even now i do not understand the essential point of mr. thomson's theory,--that is to say, its application to the phenomena of glacier motion. indeed, it was the obscurity in my mind in connexion with this point, and the hope that time might enable me to seize more clearly upon his meaning, which prevented me from giving that prominence to the theory of mr. thomson which, for aught i know, it may well deserve. i will here briefly state one or two of my difficulties, and shall feel very grateful to have them removed. [sidenote: improbable deduction.] let us fix our attention on a vertical slice of ice transverse to the glacier, and to which the pressure is applied perpendicular to its surfaces. the ice liquefies, and, supposing the means of escape offered to the compressed water to be equal all round, it is plain that there will be as great a tendency to squeeze the water upwards as downwards; for the mere tendency to flow down by its own gravity becomes, in comparison to the forces here acting on the water, a vanishing quantity. but the fact is, that the ice above the slice is more permeable than that below it; for, as we descend a glacier, the ice becomes more compact. hence the greater part of the dispersed water will be refrozen on that side of the slice which is turned towards the origin of the glacier; and the consequence is, that, according to mr. thomson's principle, the glacier ought to move up hill instead of down. i would invite mr. thomson to imagine himself and me together upon the ice, desirous of examining this question in a philosophic spirit; and that we have taken our places beside a stake driven into the ice, and descending with the glacier. we watch the ice surrounding the stake, and find that every speck of dirt upon it retains its position; there is no liquefaction of the ice that bears the dirt, and consequently it rests on the glacier undisturbed. after twelve hours we find the stake fifteen inches distant from its first position: i would ask mr. thomson how did it get there? or let us fix our attention on those six stakes which m. agassiz drove into the glacier of the aar in , and found erect in at some hundreds of feet from their first position:--how did they get there? how, in fine, does the end of a glacier become its end? has it been liquefied and re-frozen? if not, it must have been _pushed_ down by the very forces which mr. thomson invokes to produce his liquefaction. both the liquefaction, as far as it exists, and the motion, are products of the same cause. in short, this theory, as it presents itself to my mind, is so powerless to account for the simplest fact of glacier-motion, that i feel disposed to continue to doubt my own competence to understand it rather than ascribe to mr. thomson an hypothesis apparently so irrelevant to the facts which it professes to explain. another difficulty is the following:--mr. thomson will have seen that i have recorded certain winter measurements made on the mer de glace, and that these measurements show not only that the ice moves at that period of the year, but that it exhibits those characteristics of motion from which its plasticity has been inferred; the velocity of the central portions of the glacier being in round numbers double the velocity of those near the sides. had there been any necessity for it, this ratio might have been augmented by placing the side-stakes closer to the walls of the glacier. considering the extreme coldness of the weather which preceded these measurements, it is a moderate estimate to set down the temperature of the ice in which my stakes were fixed at ° cent. below zero. [sidenote: requisite pressure calculated.] let us now endeavour to estimate the pressure existing at the portion of the glacier where these measurements were made. the height of the montanvert above the sea-level is, according to prof. forbes, feet; that of the col du géant, which is the summit of the principal tributary of the mer de glace, is , feet: deducting the former from the latter, we find the height of the col du géant above the montanvert to be feet. now, according to mr. thomson's theory and his brother's experiments, the melting point of ice is lowered . ° centigrade for every atmosphere of pressure; and one atmosphere being equivalent to the pressure of about thirty-three feet of water, we shall not be over the truth if we take the height of an equivalent column of glacier-ice, of a compactness the mean of those which it exhibits upon the col du géant and at the montanvert respectively, at forty feet. the compactness of glacier ice is, of course, affected by the air-bubbles contained within it. [sidenote: actual pressure insufficient.] if, then, the pressure of forty feet of ice lower the melting point . ° centigrade, it follows that the pressure of a column feet high will lower it nine-tenths of a degree centigrade. supposing, then, the _unimpeded thrust of the whole glacier, from the col du géant downwards_, to be exerted on the ice at the montanvert; or, in other words, supposing the bed of the glacier to be absolutely smooth and every trace of friction abolished, the utmost the pressure thus obtained could perform would be to lower the melting point of the montanvert ice by the quantity above mentioned. taking into account the actual state of things, the friction of the glacier against its sides and bed, the opposition which the three tributaries encounter in the neck of the valley at trélaporte, the resistance encountered in the sinuous valley through which it passes; and finally, bearing in mind the comparatively short length of the glacier, which has to bear the thrust, and oppose the latter by its own friction merely;--i think it will appear evident that the ice at the montanvert cannot possibly have its melting point lowered by pressure more than a small fraction of a degree. the ice in which my stakes were fixed being - ° centigrade, according to mr. thomson's calculation and his brother's experiments, it would require atmospheres of pressure to liquefy it; in other words, it would require the unimpeded pressure of a column of glacier-ice , feet high. did mont blanc rise to two and a half times its present height above the montanvert, and were the latter place connected with the summit of the mountain by a continuous glacier with its bed absolutely smooth, the pressure at the montanvert would be rather under that necessary to liquefy the ice on which my winter observations were made. [sidenote: measurements apply to surface.] if it be urged that, though the temperature near the surface may be several degrees below the freezing point, the great body of the glacier does not share this temperature, but is, in all probability, near to °, my reply is simple. i did not measure the motion of the ice in the body of the glacier; nobody ever did; my measurements refer to the ice at and near the surface, and it is this ice which showed the plastic deportment which the measurements reveal. such, then, are some of the considerations which prevent me from accepting the theory of mr. thomson, and i trust they will acquit me of all desire, to make his theory co-operate with my views. i am, however, far from considering his deduction the less important because of its failing to account for the phenomena of glacier motion. the pressure-theory of glacier-motion. ( .) [sidenote: possible moulding of ice.] broadly considered, two classes of facts are presented to the glacier-observer; the one suggestive of viscosity, and the other of the reverse. the former are seen where _pressure_ comes into play, the latter where _tension_ is operative. by pressure ice can be moulded to any shape, while the same ice snaps sharply asunder if subjected to tension. were the result worth the labour, ice might be moulded into vases or statuettes, bent into spiral bars, and, i doubt not, by the proper application of pressure, a _rope_ of ice might be formed and coiled into a _knot_. but not one of these experiments, though they might be a thousandfold more striking than any ever made upon a glacier, would in the least demonstrate that ice is really a viscous body. [illustration: fig. . moulds used in experiments with ice.] i have here stated what i believe to be feasible. let me now refer to the experiments which have been actually made in illustration of this point. two pieces of seasoned box-wood had corresponding cavities hollowed in them, so that, when one was placed upon the other, a lenticular space was enclosed. a and b, fig. , represent the pieces of box-wood with the cavities in plan: c represents their section when they are placed upon each other. [sidenote: actual moulding of ice.] a _sphere_ of ice rather more than sufficient to fill the lenticular space was placed between the pieces of wood and subjected to the action of a small hydraulic press. the ice was crushed, but the crushed fragments soon reattached themselves, and, in a few seconds, a lens of compact ice was taken from the mould. [illustration: fig. . moulds used in experiments with ice.] this lens was placed in a cylindrical cavity hollowed out in another piece of box-wood, and represented at c, fig. ; and a flat piece of the wood was placed over the lens as a cover, as at d. on subjecting the whole to pressure, the lens broke, as the sphere had done, but the crushed mass soon re-established its continuity, and in less than half a minute a compact cake of ice was taken from the mould. [illustration: fig. . moulds used in experiments with ice.] in the following experiment the ice was subjected to a still severer test:--a hemispherical cavity was formed in one block of box-wood, and upon a second block a hemispherical protuberance was turned, smaller than the cavity, so that, when the latter was placed in the former, a space of a quarter of an inch existed between the two. fig. represents a section of the two pieces of box-wood; the brass pins _a_, _b_, fixed in the slab g h, and entering suitable apertures in the mould i k, being intended to keep the two surfaces concentric. a lump of ice being placed in the cavity, the protuberance was brought down upon it, and the mould subjected to hydraulic pressure: after a short interval the ice was taken from the mould as a smooth compact _cup_, its crushed particles having reunited, and established their continuity. [sidenote: ice moulded to cups and rings.] [illustration: fig. . moulds used in experiments with ice.] to make these results more applicable to the bending of glacier-ice, the following experiments were made:--a block of box-wood, m, fig. , inches long, wide, and deep, had its upper surface slightly curved, and a groove an inch wide, and about an inch deep, worked into it. a corresponding plate was prepared, having its under surface part of a convex cylinder, of the same curvature as the concave surface of the former piece. when the one slab was placed upon the other, they presented the appearance represented in section at n. a straight prism of ice inches long, an inch wide, and a little more than an inch in depth, was placed in the groove; the upper slab was placed upon it, and the whole was subjected to the hydraulic press. the prism broke, but, the quantity of ice being rather more than sufficient to fill the groove, the pressure soon brought the fragments together and re-established the continuity of the ice. after a few seconds it was taken from the mould a bent bar of ice. this bar was afterwards passed through three other moulds of gradually augmenting curvature, and was taken from the last of them a _semi-ring_ of compact ice. the ice, in changing its form from that of one mould to that of another, was in every instance broken and crushed by the pressure; but suppose that instead of three moulds three thousand had been used; or, better still, suppose the curvature of a single mould to change by extremely slow degrees; the ice would then so gradually change its form that no rude rupture would be apparent. practically the ice would behave as a _plastic_ substance; and indeed this plasticity has been contended for by m. agassiz, in opposition to the idea of viscosity. as already stated, the ice, bruised, and flattened, and bent in the above experiments, was incapable of being sensibly stretched; it was plastic to pressure but not to tension. a quantity of water was always squeezed out of the crushed ice in the above experiments, and the bruised fragments were intermixed with this and with air. minute quantities of both remained in the moulded ice, and thus rendered it in some degree turbid. its character, however, as to continuity may be inferred from the fact that the ice-cup, moulded as described, held water without the slightest visible leakage. [sidenote: softness of ice defined.] [sidenote: pressure and tension.] ice at ° may, as already stated, be crushed with extreme facility, and glacier-ice with still more readiness than lake-ice: it may also be scraped with a knife with even greater facility than some kinds of chalk. in comparison with ice at ° below the freezing point, it might be popularly called _soft_. but its softness is not that of paste, or wax, or treacle, or lava, or honey, or tar. it is the softness of calcareous spar in comparison with that of rock-crystal; and although the latter is incomparably harder than the former, i think it will be conceded that the term viscous would be equally inapplicable to both. my object here is clearly to define terms, and not permit physical error to lurk beneath them. how far this ice, with a softness thus defined, when subjected to the gradual pressures exerted in a glacier, is bruised and broken, and how far the motion of its parts may approach to that of a truly viscous body under pressure, i do not know. the critical point here is that the ice changes its form, and preserves its continuity, during its motion, in virtue of _external_ force. it remains continuous whilst it moves, because its particles are kept in juxtaposition by pressure, and when this external prop is removed, and the ice, subjected to tension, has to depend solely upon the mobility of its own particles to preserve its continuity, the analogy with a viscous body instantly breaks down.[a] footnotes: [a] "imagine," writes professor forbes, "a long narrow trough or canal, stopped at both ends and filled to a considerable depth with treacle, honey, tar, or any such viscid fluid. imagine one end of the trough to give way, the bottom still remaining horizontal: if the friction of the fluid against the bottom be greater than the friction against its own particles, the upper strata will roll over the lower ones, and protrude in a convex slope, which will be propagated backwards towards the other or closed end of the trough. had the matter been quite fluid the whole would have run out, and spread itself on a level: as it is, it assumes precisely the conditions which we suppose to exist in a glacier." this is perfectly definite, and my equally definite opinion is that no glacier ever exhibited the mechanical effects implied by this experiment. regelation. ( .) [sidenote: faraday's first experiment.] i was led to the foregoing results by reflecting on an experiment performed by mr. faraday, at a friday evening meeting of the royal institution, on the th of june, , and described in the 'athenæum' and 'literary gazette' for the same month. mr. faraday then showed that when two pieces of ice, with moistened surfaces, were placed in contact, they became cemented together by the freezing of the film of water between them, while, when the ice was below ° fahr., and therefore _dry_, no effect of the kind could be produced. the freezing was also found to take place under water; and indeed it occurs even when the water in which the ice is plunged is as hot as the hand can bear. a generalisation from this interesting fact led me to conclude that a bruised mass of ice, if closely confined, must re-cement itself when its particles are brought into contact by pressure; in fact, the whole of the experiments above recorded immediately suggested themselves to my mind as natural deductions from the principle established by faraday. a rough preliminary experiment assured me that the deductions would stand testing; and the construction of the box-wood moulds was the consequence. we could doubtless mould many solid substances to any extent by suitable pressure, breaking the attachment of their particles, and re-establishing a certain continuity by the mere force of cohesion. with such substances, to which we should never think of applying the term viscous, we might also imitate the changes of form to which glaciers are subject: but, superadded to the mere cohesion which here comes into play, we have, in the case of ice, the actual regelation of the severed surfaces, and consequently a more perfect solid. in the introduction to this book i have referred to the production of slaty cleavage by pressure; and at a future page i hope to show that the lamination of the ice of glaciers is due to the same cause; but, as justly observed by mr. john ball, there is no tendency to cleave in the _sound_ ice of glaciers; in fact, this tendency is obliterated by the perfect regelation of the severed surfaces. [sidenote: recent experiments of faraday.] mr. faraday has recently placed pieces of ice, in water, under the strain of forces tending to pull them apart. when two such pieces touch at a single point they adhere and move together as a rigid piece; but a little lateral force carefully applied breaks up this union with a crackling noise, and a new adhesion occurs which holds the pieces together in opposition to the force which tends to divide them. mr. james thomson had referred regelation to the cold produced by the liquefaction of the pressed ice; but in the above experiment all pressure is not only taken away, but is replaced by tension. mr. thomson also conceives that, when pieces of ice are simply placed together without intentional pressure, the capillary attraction brings the pressure of the atmosphere into play; but mr. faraday finds that regelation takes place _in vacuo_. a true viscidity on the part of ice mr. faraday never has observed, and he considers that his recent experiments support the view originally propounded by himself, namely, that a particle of water on a surface of ice becomes solid when placed between two surfaces, because of the increased influence due to their joint action. crystallization and internal liquefaction. ( .) [sidenote: how crystals are "nursed."] in the introduction to this book i have briefly referred to the force of crystallization. to permit this force to exercise its full influence, it must have free and unimpeded action; a crystal, for instance, to be properly built, ought to be suspended in the middle of the crystallizing solution, so that the little architects can work all round it; or if placed upon the bottom of a vessel, it ought to be frequently turned, so that all its facets may be successively subjected to the building process. in this way crystals can be _nursed_ to an enormous size. but where other forces mingle with that of crystallization, this harmony of action is destroyed; the figures, for example, that we see upon a glass window, on a frosty morning, are due to an action compounded of the pure crystalline force and the cohesion of the liquid to the window-pane. a more regular effect is obtained when the freezing particles are suspended in still air, and here they build themselves into those wonderful figures which dr. scoresby has observed in the polar regions, mr. glaisher at greenwich, and i myself on the summit of monte rosa and elsewhere. not only however in air, but in water also, figures of great beauty are sometimes formed. harrison's excellent machine for the production of artificial ice is, i suppose, now well known; the freezing being effected by carrying brine, which had been cooled by the evaporation of ether, round a series of flat tin vessels containing water. the latter gradually freezes, and, on watching those vessels while the action was proceeding very slowly, i have seen little six-rayed stars of thin ice forming, and rising to the surface of the liquid. i believe the fact was never before observed, but it would be interesting to follow it up, and to develop experimentally this most interesting case of crystallization. [sidenote: dissection of ice by sunbeam.] the surface of a freezing lake presents to the eye of the observer nothing which could lead him to suppose that a similar molecular architecture is going on there. still the particles are undoubtedly related to each other in this way; they are arranged together on this starry type. and not only is this the case at the surface, but the largest blocks of ice which reach us from norway and the wenham lake are wholly built up in this way. we can reveal the internal constitution of these masses by a reverse process to that which formed them; we can send an agent into the interior of a mass of ice which shall take down the atoms which the crystallizing forces had set up. this agent is a solar beam; with which it first occurred to me to make this simple experiment in the autumn of . i placed a large converging lens in the sunbeams passing through a room, and observed the place where the rays were brought to a focus behind the lens; then shading the lens, i placed a clear cube of ice so that the point of convergence of the rays might fall within it. on removing the screen from the lens, a cone of sunlight went through the cube, and along the course of the cone the ice became studded with lustrous spots, evidently formed by the beam, as if minute reflectors had been suddenly established within the mass, from which the light flashed when it met them. on examining the cube afterwards i found that each of these spots was surrounded by a liquid flower of six petals; such flowers were distributed in hundreds through the ice, being usually clear and detached from each other, but sometimes crowded together into liquid bouquets, through which, however, the six-starred element could be plainly traced. at first the edges of the leaves were unbroken curves, but when the flowers expanded under a long-continued action, the edges became serrated. when the ice was held at a suitable angle to the solar beams, these liquid blossoms, with their central spots shining more intensely than burnished silver, presented an exhibition of beauty not easily described. i have given a sketch of their appearance in fig. . [sidenote: liquid flowers in ice.] [illustration: fig. . liquid flowers in lake ice.] i have here to direct attention to an extremely curious fact. on sending the sunbeam through the transparent ice, i often noticed that the appearance of the lustrous spots was accompanied by an audible clink, as if the ice were ruptured inwardly. but there is no ground for assuming such rupture, and on the closest examination no flaw is exhibited by the ice. what then can be the cause of the noise? i believe the following considerations will answer the question:-- water always holds a quantity of air in solution, the diffusion of which through the liquid, as proved by m. donny, has an immense effect in weakening the cohesion of its particles; recent experiments of my own show that this is also the case in an eminent degree with many volatile liquids. m. donny has proved that, if water be thoroughly purged of its air, a long glass tube filled with this liquid may be inverted, while the tenacity with which the water clings to the tube, and with which its particles cling to each other, is so great that it will remain securely suspended, though no external hindrance be offered to its descent. owing to the same cause, water deprived of its air will not boil at ° fahr., and may be raised to a temperature of nearly ° without boiling; but when this occurs the particles break their cohesion suddenly, and ebullition is converted into explosion. now, when ice is formed, every trace of the air which the water contained is squeezed out of it; the particles in crystallizing reject all extraneous matter, so that in ice we have a substance quite free from the air, which is never absent in the case of water; it therefore follows that if we could preserve the water derived from the melting of ice from contact with the atmosphere, we should have a liquid eminently calculated to show the effects described by m. donny. mr. faraday has proved by actual experiment that this is the case. [sidenote: water deprived of air snaps asunder.] let us apply these facts to the explanation of the clink heard in my experiments. on sending a sunbeam through ice, liquid cavities are suddenly formed at various points within the mass, and these cavities are completely cut off from atmospheric contact. but the water formed by the melting ice is less in volume than the ice which produces it; the water of a cavity is not able to fill it, hence a vacuous space must be formed in the cell. i have no doubt that, for a time, the strong cohesion between the walls of the cell and the drop within it augments the volume of the latter a little, so as to compel it to fill the cell; but as the quantity of liquid becomes greater the shrinking force augments, until finally the particles snap asunder like a broken spring. at the same moment a lustrous spot appears, which is a vacuum, and simultaneously with the appearance of this vacuum the clink was always heard. multitudes of such little explosions must be heard upon a glacier when the strong summer sun shines upon it, the aggregate of which must, i think, contribute to produce the "crepitation" noticed by m. agassiz, and to which i have already referred. [sidenote: figures in ice; vacuous spots.] in plate vi. of the atlas which accompanies the 'système glaciaire' of m. agassiz, i notice drawings of figures like those i have described, which he has observed in glacier-ice, and which were doubtless produced by direct solar radiation. i have often myself observed figures of exquisite beauty formed in the ice on the surface of glacier-pools by the morning sun. in some cases the spaces between the leaves of the liquid flowers melt partially away, and leave the central spot surrounded by a crimped border; sometimes these spaces wholly disappear, and the entire space bounded by the lines drawn from point to point of the leaves becomes liquid, thus forming perfect hexagons. the crimped borders exhibit different degrees of serration, from the full leaves themselves to a gentle undulating line, which latter sometimes merges into a perfect circle. in the ice of glaciers, i have seen the internal liquefaction ramify itself like sprigs of myrtle; in the same ice, and particularly towards the extremities of the glacier, disks innumerable are also formed, consisting of flat round liquid spaces, a bright spot being usually associated with each. these spots have been hitherto mistaken for air-bubbles; but both they and the lustrous disks at the centres of the flowers are vacuous. i proved them to be so by plunging the ice containing them into hot water, and watching what occurred when the walls of the cells were dissolved, and a liquid connexion established between them and the atmosphere. in all cases they totally collapsed, and no trace of air rose to the surface of the warm water. no matter in what direction a solar beam is sent through lake-ice, the liquid flowers are all formed parallel to the surface of freezing. the beam may be sent parallel, perpendicular, or oblique to this surface; the flowers are always formed in the same planes. every line perpendicular to the surface of a frozen lake is in fact an axis of symmetry, round which the molecules so arrange themselves, that, when taken down by the delicate fingers of the sunbeam, the six-leaved liquid flowers are the result. in the ice of glaciers we have no definite planes of freezing. it is first snow, which has been disturbed by winds while falling, and whirled and tossed about by the same agency after it has fallen, being often melted, saturated with its own water, and refrozen: it is cast in shattered fragments down cascades, and reconsolidated by pressure at the bottom. in ice so formed and subjected to such mutations, definite planes of freezing are, of course, out of the question. [sidenote: constitution of glacier-ice.] the flat round disks and vacuous spots to which i have referred come here to our aid, and furnish us with an entirely new means of analysing the internal constitution of a glacier. when we examine a mass of glacier-ice which contains these disks, we find them lying in all imaginable planes; not confusedly, however--closer examination shows us that the disks are arranged in groups, the members of each group being parallel to a common plane, but the parallelism ceases when different groups are compared. the effect is exactly what would be observed, supposing ordinary lake-ice to be broken up, shaken together, and the confused fragments regelated to a compact continuous mass. in such a jumble the original planes of freezing would lie in various directions; but no matter how compact or how transparent ice thus constituted might appear, a solar beam would at once reveal its internal constitution by developing the flowers parallel to the planes of freezing of the respective fragments. a sunbeam sent through glacier-ice always reveals the flowers in the planes of the disks, so that the latter alone at once informs us of its crystalline constitution. [sidenote: vacuous cells mistaken for air-cells.] hitherto, as i have said, these disks have been mistaken for bubbles containing air, and their flattening has been ascribed to the pressure to which they have been subjected. m. agassiz thus refers to them:--"the air-bubbles undergo no less curious modifications. in the neighbourhood of the _névé_, where they are most numerous, those which one sees on the surface are all spherical or ovoid, but by degrees they begin to be flattened, and near the end of the glacier there are some that are so flat _that they might be taken for fissures when seen in profile_. the drawing represents a piece of ice detached from the gallery of infiltration. all the bubbles are greatly flattened. but what is most extraordinary is, that, far from being uniform, _the flattening is different in each fragment_; so that the bubbles, according to the face which they offer, appear either very broad or very thin." this description of glacier-ice is correct: it agrees with the statements of all other observers. but there are two assumptions in the description which must henceforth be given up; first, the bubbles seen like fissures in profile are not air-bubbles at all, but vacuous spots, which the very constitution of ice renders a necessary concomitant of its inward melting; secondly, the assumption that the bubbles have been _flattened_ by pressure must be abandoned; for they are found, and may be developed at will, in lake-ice on which no pressure has been exerted. [sidenote: cells of air and water.] but these remarks dispose only of a certain class of cells contained in glacier-ice. besides the liquid disks and vacuous spots, there are innumerable true bubbles entangled in the mass. these have also been observed and described by m. agassiz; and mr. huxley has also given us an accurate account of them. m. agassiz frequently found air and water associated in the same cell. mr. huxley found no exception to the rule: in each case the bubble of air was enclosed in a cell which was also partially filled with water. he supposes that the water may be that of the originally-melted snow which has been carried down from the _névé_ unfrozen. this hypothesis is worthy of a great deal more consideration than i have had time to give to it, and i state it here in the hope that it will be duly examined. my own experience of these associated air and water cells is derived almost exclusively from lake-ice, in which i have often observed them in considerable numbers. in examining whether the liquid contents had ever been frozen or not, i was guided by the following considerations. if the air be that originally entangled in the solid, it will have the ordinary atmospheric density at least; but if it be due to the melting of the walls of the cell, then the water so formed being only eight-ninths of that of the ice which produced it, _the air of the bubble must be rarefied_. i suppose i have made a hundred different experiments upon these bubbles to determine whether the air was rarefied or not, and in every case found it so. ice containing the bubbles was immersed in warm water, and always, when the rigid envelope surrounding a bubble was melted away, the air suddenly collapsed to a fraction of its original dimensions. i think i may safely affirm that, in some cases, the collapse reduced the bubbles to the thousandth part of their original volume. from these experiments i should undoubtedly infer, that in lake-ice at least, the liquid of the cells is produced by the melting of the ice surrounding the bubbles of air. but i have not subjected the bubbles of glacier-ice to the same searching examination. i have tried whether the insertion of a pin would produce the collapse of the bubbles, but it did not appear to do so. i also made a few experiments at rosenlaui, with warm water, but the result was not satisfactory. that ice melts internally at the surfaces of the bubbles is, i think, rendered certain by my experiments, but whether the water-cells of glacier-ice are entirely due to such melting, subsequent observers will no doubt determine. [sidenote: "liquid liberty."] i have found these composite bubbles at all parts of glaciers; in the ice of the moraines, over which a protective covering had been thrown; in the ice of sand-cones, after the removal of the superincumbent débris; also in ice taken from the roofs of caverns formed in the glacier, and which the direct sunlight could hardly by any possibility attain. that ice should liquefy at the surface of a cavity is, i think, in conformity with all we know concerning the physical nature of heat. regarding it as a motion of the particles, it is easy to see that this motion is less restrained at the surface of a cavity than in the solid itself, where the oscillation of each atom is controlled by the particles which surround it; hence _liquid liberty_, if i may use the term, is first attained at the surface. indeed i have proved by experiment that ice may be melted internally by heat which has been conducted through its external portions without melting them. these facts are the exact complements of those of "regelation;" for here, two moist surfaces of ice being brought into close contact, their liquid liberty is destroyed and the surfaces freeze together. the moulins. ( .) [sidenote: moulin of grindelwald glacier.] [sidenote: depth of the shaft.] the first time i had an opportunity of seeing these remarkable glacier-chimneys was in the summer of , upon the lower glacier of grindelwald. mr. huxley was my companion at the time, and on crossing the so-called eismeer we heard a sound resembling the rumble of distant thunder, which proceeded from a perpendicular shaft formed in the ice, and into which a resounding cataract discharged itself. the tube in fact resembled a vast organ-pipe, whose thunder-notes were awakened by the concussion of the falling water, instead of by the gentle flow of a current of air. beside the shaft our guide hewed steps, on which we stood in succession, and looked into the tremendous hole. near the first shaft was a second and smaller one, the significance of which i did not then understand; it was not more than feet deep, but seemed filled with a liquid of exquisite blue, the colour being really due to the magical shimmer from the walls of the moulin, which was quite empty. as far as we could see, the large shaft was vertical, but on dropping a stone into it a shock was soon heard, and after a succession of bumps, which occupied in all seven seconds, we heard the stone no more. the depth of the moulin could not be thus ascertained, but we soon found a second and still larger one which gave us better data. a stone dropped into this descended without interruption for four seconds, when a concussion was heard; and three seconds afterwards the final shock was audible: there was thus but a single interruption in the descent. supposing all the acquired velocity to have been destroyed by the shock, by adding the space passed over by the stone in four and in three seconds respectively, and making allowance for the time required by the sound to ascend from the bottom, we find the depth of the shaft to be about feet. there is, however, no reason to suppose that this measures the depth of the glacier at the place referred to. these shafts are to be found in almost all great glaciers; they are very numerous in the unteraar glacier, numbers of them however being empty. on the mer de glace they are always to be found in the region of trélaporte, one of the shafts there being, _par excellence_, called the grand moulin. many of them also occur on the glacier de léchaud. as truly observed by m. agassiz, these moulins occur only at those parts of the glacier which are not much rent by fissures, for only at such portions can the little rills produced by superficial melting collect to form streams of any magnitude. the valley of unbroken ice formed in the mer de glace near trélaporte is peculiarly favourable for the collection of such streams; we see the little rills commencing, and enlarging by the contributions of others, the trunk-rill pouring its contents into a little stream which stretches out a hundred similar arms over the surface of the glacier. several such streams join, and finally a considerable brook, which receives the superficial drainage of a large area, cuts its way through the ice. [sidenote: moulins explained.] but although this portion of the glacier is free from those long-continued and permanent strains which, having once rent the ice, tend subsequently to widen the rent and produce yawning crevasses, it is not free from local strains sufficient to produce _cracks_ which penetrate the glacier to a great depth. imagine such a crack intersecting such a glacier-rivulet as we have described. the water rushes down it, and soon scoops a funnel large enough to engulf the entire stream. the moulin is thus formed, and, as the ice moves downward, the sides of the crack are squeezed together and regelated, the seam which marks the line of junction being in most cases distinctly visible. but as the motion continues, other portions of the glacier come into the same state of strain as that which produced the first crack; a second one is formed across the stream, the old shaft is forsaken, and a new one is hollowed out, in which for a season the cataract plays the thunderer. i have in some cases counted the forsaken shafts of six old moulins in advance of an active one. not far from the grand moulin of the mer de glace in there was a second empty shaft, which evidently communicated by a subglacial duct with that into which the torrent was precipitated. out of the old orifice issued a strong cold blast, the air being manifestly impelled through the duct by the falling water of the adjacent moulin. these shafts are always found in the same locality; the portion of the mer de glace to which i have referred is never without them. some of the guides affirm that they are motionless; and a statement of prof. forbes has led to the belief that this was also his opinion.[a] m. agassiz, however, observed the motion of some of these shafts upon the glacier of the aar; and when on the spot in , i was anxious to decide the point by accurate measurements with the theodolite. my friend mr. hirst took charge of the instrument, and on the th of july i fixed a single stake beside the grand moulin, in a straight line between a station at trélaporte and a well-defined mark on the rock at the opposite side of the valley. on the st, the displacement of the stake amounted to inches, and on the st of august it had moved - / inches--the moulin, to all appearance, occupying throughout the same position with regard to the stake. to render this certain, moreover we subsequently drove two additional stakes into the ice, thus enclosing the mouth of the shaft in a triangle. on the th of august the displacements were measured and gave the following results:-- total motion. first (old) stake inches. second (new) do. " third " [sidenote: motion of the moulins.] the old stake had been fixed for days, and its daily motion--_which was also that of the moulin_--averaged inches a day. hence the moulins share the general motion of the glacier, and their apparent permanence is not, as has been alleged, a proof of the semi-fluidity of the glacier, but is due to the breaking of the ice as it passes the place of local strain. [sidenote: depth of "grand moulin" sought.] wishing to obtain some estimate as to the depth of the ice, mr. hirst undertook the sounding of some of the moulins upon the glacier de léchaud, making use of a tin vessel filled with lumps of lead and iron as a weight. the cord gave way and he lost his plummet. to measure the depth of the grand moulin, we obtained fresh cord from chamouni, to which we attached a four-pound weight. into a cavity at the bottom of the weight we stuffed a quantity of butter, to indicate the nature of the bottom against which the weight might strike. the weight was dropped into the shaft, and the cord paid out until its slackening informed us that the weight had come to rest; by shaking the string, however, and walking round the edge of the shaft, the weight was liberated, and sank some distance further. the cord partially slackened a second time, but the strain still remaining was sufficient to render it doubtful whether it was the weight or the action of the falling water which produced it. we accordingly paid out the cord to the end, but, on withdrawing it, found that the greater part of it had been coiled and knotted up by the falling water. we uncoiled, and sounded again. at a depth of feet the weight reached a ledge or protuberance of ice, and by shaking and lifting it, it was caused to descend feet more. a depth of feet was the utmost we could attain to. we sounded the old moulin to a depth of feet; while a third little shaft, beside the large one, measured only feet in depth. we could see the water escape from it through a lateral canal at its bottom, and doubtless the water of the grand moulin found a similar exit. there was no trace of dirt upon the butter, which might have indicated that we had reached the bed of the glacier. footnotes: [a] "every year, and year after year, the watercourses follow the same lines of direction--their streams are precipitated into the heart of the glacier by vertical funnels, called 'moulins,' at the very same points."--forbes's fourth letter upon glaciers: 'occ. pap.,' p. . [illustration: dirt-bands of the mer de glace, as seen from a point near the flÉgÈre. fig. . _to face p. ._] dirt-bands of the mer de glace. ( .) [sidenote: dirt-bands from the flegÈre.] these bands were first noticed by prof. forbes on the th of july, , and were described by him in the following words:--"my eye was caught by a very peculiar appearance of the surface of the ice, which i was certain that i now saw for the first time. it consisted of nearly hyperbolic brownish bands on the glacier, the curves pointing downwards, and the two branches mingling indiscriminately with the moraines, presenting an appearance of a succession of waves some hundred feet apart."[a] from no single point of view hitherto attained can all the dirt-bands of the mer de glace be seen at once. to see those on the terminal portion of the glacier, a station ought to be chosen on the opposite range of the brévent, a few hundred yards beyond the croix de la flegère, where we stand exactly in front of the glacier as it issues into the valley of chamouni. the appearance of the bands upon the portion here seen is represented in fig. . it will be seen that the bands are confined to one side of the glacier, and either do not exist, or are obliterated by the débris, upon the other side. the cause of the accumulation of dirt on the right side of the glacier is, that no less than five moraines are crowded together at this side. in the upper portions of the mer de glace these moraines are distinct from each other; but in descending, the successive engulfments and disgorgings of the blocks and dirt have broken up the moraines; and at the place now before us the materials which composed them are strewn confusedly on the right side of the glacier. the portion of the ice on which the dirt-bands appear is derived from the col du géant. they do not quite extend to the end of the glacier, being obliterated by the dislocation of the ice upon the frozen cascade of des bois. [sidenote: dirt-bands from les charmoz.] let us now proceed across the valley of chamouni to the montanvert; where, climbing the adjacent heights to an elevation of six or eight hundred feet above the hotel, we command a view of the mer de glace, from trélaporte almost to the commencement of the glacier des bois. it was from this position that professor forbes first observed the bands. fifteen, sixteen, and seventeen years later i observed them from the same position. the number of bands which professor forbes counted from this position was eighteen, with which my observations agree. the entire series of bands which i observed, with the exception of one or two, must have been the _successors_ of those observed by professor forbes; and my finding the same number after an interval of so many years proves that the bands must be due to some regularly recurrent cause. fig. represents the bands as seen from the heights adjacent to the montanvert. [illustration: dirt-bands of the mer de glace, as seen from les charmoz. fig. . _to face p. ._] i would here direct attention to an analogy between a glacier and a river, which may be observed from the heights above the montanvert, but to which no reference, as far as i know, has hitherto been made. when a river meets the buttress of a bridge, the water rises against it, and, on sweeping round it, forms an elevated ridge, between which and the pier a depression occurs which varies in depth with the force of the current. this effect is shown by the mer de glace on an exaggerated scale. sweeping round trélaporte, the ice pushes itself beyond the promontory in an elevated ridge, from which it drops by a gradual slope to the adjacent wall of the valley, thus forming a depression typified by that already alluded to. a similar effect is observed at the opposite side of the glacier on turning round the echelets; and both combine to form a kind of skew surface. a careful inspection of the frontispiece will detect this peculiarity in the shape of the glacier. [sidenote: from the cleft-station.] from neither of the stations referred to do we obtain any clue to the origin of the dirt-bands. a stiff but pleasant climb will place us in that singular cleft in the cliffy mountain-ridge which is seen to the right of the frontispiece; and from it we easily attain the high platform of rock immediately to the left of it. we stand here high above the promontory of trélaporte, and occupy the finest station from which the mer de glace and its tributaries can be viewed. from this station we trace the dirt-bands over most of the ice that we have already scanned, and have the further advantage of being able to follow them to their very source. this source is the grand ice-cascade which descends in a succession of precipices from the plateau of the col du géant into the valley which the glacier du géant fills. we see from our present point of view that the bands _are confined to the portion of the glacier which has descended the cascade_. fig. represents the bands as seen from the cleft-station above trélaporte. [illustration: dirt-bands of the mer de glace, as seen from the cleft station, trÉlaporte. fig. . _to face p. ._] we are now however at such a height above the glacier and at such a distance from the base of the cascade, that we can form but an imperfect notion of the true contour of the surface. let us therefore descend, and walk up the glacier du géant towards the cascade. at first our road is level, but we gradually find that at certain intervals we have to ascend slopes which follow each other in succession, each being separated from its neighbour by a space of comparatively level ice. the slopes increase in steepness as we ascend; they are steepest, moreover, on the right-hand side of the glacier, where it is bounded by that from the périades, and at length we are unable to climb them without the aid of an axe. soon afterwards the dislocation of the glacier becomes considerable; we are lost in the clefts and depressions of the ice, and are unable to obtain a view sufficiently commanding to subdue these local appearances and convey to us the general aspect. we have at all events satisfied ourselves as to the existence, on the upper portion of the glacier, of a succession of undulations which sweep transversely across it. the term "wrinkles," applied to them by prof. forbes, is highly suggestive of the appearance which they present. [sidenote: snow-bands on the glacier du gÉant.] from the cleft-station bands of snow may also be seen partially crossing the glacier in correspondence with the undulations upon its surface. if the quantity deposited the winter previous be large, and the heat of summer not too great, these bands extend quite across the glacier. they were first observed by professor forbes in . in his fifth letter is given an illustrative diagram, which, though erroneous as regards the position of the veined structure, is quite correct in limiting the snow-bands to the glacier du géant proper. at the place where the three welded tributaries of the mer de glace squeeze themselves through the strait of trélaporte, the bands undergo a considerable modification in shape. near their origin they sweep across the glacier du géant in gentle curves, with their convexities directed downwards; but at trélaporte these curves, the chords of which a short time previous measured a thousand yards in length, have to squeeze themselves through a space of four hundred and ninety-five yards wide; and as might be expected, they are here suddenly sharpened. the apex of each being thrust forward, they take the form of sharp hyperbolas, and preserve this character throughout the entire length of the mer de glace. i would now conduct the reader to a point from which a good general view of the ice cascade of the géant is attainable. from the old moraine near the lake of the tacul we observe the ice, as it descends the fall, to be broken into a succession of precipices. it would appear as if the glacier had its back periodically broken at the summit of the fall, and formed a series of vast chasms separated from each other by cliffy ridges of corresponding size. these, as they approach the bottom of the fall, become more and more toned down by the action of sun and air, and at some distance below the base of the cascade they are subdued so as to form the transverse undulations already described. these undulations are more and more reduced as the glacier descends; and long before the tacul is attained, every sensible trace of them has disappeared. the terraces of the ice-fall are referred to by professor forbes in his thirteenth letter, where he thus describes them:--"the ice-falls succeed one another at regulated intervals, which appear to correspond to the renewal of each summer's activity in those realms of almost perpetual frost, when a swifter motion occasions a more rapid and wholesale projection of the mass over the steep, thus forming curvilinear terraces like vast stairs, which appear afterwards by consolidation to form the remarkable protuberant wrinkles on the surface of the glacier du géant." [sidenote: forbes's explanation.] with regard to the cause of the distribution of the dirt in bands, professor forbes writes thus in his third letter:--"i at length assured myself that it was entirely owing to the structure of the ice, which retains the dirt diffused by avalanches and the weather on those parts which are most porous, whilst the compacter portion is washed clean by the rain, so that those bands are nothing more than visible traces of the direction of the internal icy structure." professor forbes's theory, at that time, was that the glacier is composed throughout of a series of alternate segments of hard and porous ice, in the latter of which the dirt found a lodgment. i do not know whether he now retains his first opinion; but in his fifteenth letter he speaks of accounting for "the less compact structure of the ice beneath the dirt-band." it appears to me that in the above explanation cause has been mistaken for effect. the ice on which the dirt-bands rest certainly appears to be of a spongier character than the cleaner intermediate ice; but instead of this being the cause of the dirt-bands, the latter, i imagine, by their more copious absorption of the sun's rays and the consequent greater disintegration of the ice, are the cause of the apparent porosity. i have not been able to detect any relative porosity in the "internal icy structure," nor am i able to find in the writings of professor forbes a description of the experiments whereby he satisfied himself that this assumed difference exists. [sidenote: transverse undulations.] [sidenote: influence of direction of glacier.] several days of the summer of were devoted by me to the examination of these bands. i then found the bases and the frontal slopes of the undulations to which i have referred covered with a fine brown mud. these slopes were also, in some cases, covered with snow which the great heat of the weather had not been able entirely to remove. at places where the residue of snow was small its surface was exceedingly dirty--so dirty indeed that it appeared as if peat-mould had been strewn over it; its edges particularly were of a black brown. it was perfectly manifest that this snow formed a receptacle for the fine dirt transported by the innumerable little rills which trickled over the glacier. the snow gradually wasted, but it left its sediment behind, and thus each of the snowy bands observed by professor forbes in , contributed to produce an appearance perfectly antithetical to its own. i have said that the frontal slopes of the undulations were thus covered; and it was on these, and not in the depressions, that the snow principally rested. the reason of this is to be found in the _bearing_ of the glacier du géant, which, looking downwards, is about fourteen degrees east of the meridian.[b] hence the frontal slopes of the undulations have a _northern aspect_, and it is this circumstance which, in my opinion, causes the retention of the snow upon them. irrespective of the snow, the mere tendency of the dirt to accumulate at the bases of the undulations would also produce bands, and indeed does so on many glaciers; but the precision and beauty of the dirt-bands of the mer de glace are, i think, to be mainly referred to the interception by the snow of the fine dark mud before referred to on the northern slopes of its undulations. [sidenote: bands do not cross moraines.] were the statements of some writers upon this subject well founded, or were the dirt-bands as drawn upon the map of professor forbes correctly shown, this explanation could not stand a moment. it has been urged that the dirt-bands cannot thus belong to a single tributary of the mer de glace; for if they did, they would be confined to that tributary upon the trunk-glacier; whereas the fact is that they extend quite across the trunk, and intersect the moraines which divide the glacier du géant from its fellow-tributaries. from my first acquaintance with the mer de glace i had reason to believe that this statement was incorrect; but last year i climbed a third time to the cleft-station for the purpose of once more inspecting the bands from this fine position. i was accompanied by dr. frankland and auguste balmat, and i drew the attention of both particularly to this point. neither of them could discern, nor could i, the slightest trace of a dirt-band crossing any one of the moraines. upon the trunk-stream they were just as much confined to the glacier du géant as ever. if the bands even existed east of the moraines, they could not be seen, the dirt on this part of the glacier being sufficient to mask them. the following interesting fact may perhaps have contributed to the production of the error referred to. opposite to trélaporte the eastern arms of the dirt-bands run so obliquely into the moraine of la noire that the latter appears to be a tangent to them. but this moraine runs along the mer de glace, not far from its centre, and consequently the point of contact of each dirt-band with the moraine moves more quickly than the point of contact of the western arm of the same band with the side of the valley. hence there is a tendency to _straighten_ the bands; and at some distance down the glacier the effect of this is seen in the bands abutting against the moraine of la noire at a larger angle than before. the branches thus abutting have, i believe, been ideally prolonged across the moraines. [illustration: fig. . plan of dirt-bands taken from johnson's 'physical atlas.'] on the map published by prof. forbes in the bands are shown crossing the medial moraines of the mer de glace; and they are also thus drawn on the map in johnson's 'physical atlas' published in . the text is also in accordance with the map:--"opposite to the montanvert, and beyond les echelets, the curved loops (dirt-bands) extend _across the entire glacier_. they are single, and therefore _cut_ the medial moraine, though at a very slight angle."--'travels,' p. . the italics here belong to prof. forbes. in order to help future observers to place this point beyond doubt, i annex, in fig. , a portion of the map of the mer de glace taken from the atlas referred to. if it be compared with fig. the difference between prof. forbes and myself will be clearly seen. the portion of the glacier represented in both diagrams may be viewed from the point near the flegère already referred to. [sidenote: annual "rings."] the explanation which i have given involves three considerations:--the transverse breaking of the glacier on the cascade, and the gradual accumulation of the dirt in the hollows between the ridges; the subsequent toning down of the ridges to gentle protuberances which sweep across the glacier; and the collection of the dirt upon the slopes and at the bases of these protuberances. whether the periods of transverse fracture are annual or not--whether the "wrinkles" correspond to a yearly gush--and whether, consequently, the dirt-bands mark the growth of a glacier as the "annual rings" mark the growth of a tree, i do not know. it is a conjecture well worthy of consideration; but it is only a conjecture, which future observation may either ratify or refute. footnotes: [a] 'travels,' page . [b] in the large map of professor forbes the bearing of the valley is nearly sixty degrees west of the meridian; but this is caused by the true north being drawn on the wrong side of the magnetic north; thus making the declination easterly instead of westerly. in the map in johnson's 'physical atlas' this mistake is corrected. the veined structure of glaciers. ( .) [sidenote: general appearance.] the general appearance of the veined structure may be thus briefly described:--the ice of glaciers, especially midway between their mountain-sources and their inferior extremities, is of a whitish hue, caused by the number of small air-bubbles which it contains, and which, no doubt, constitute the residue of the air originally entrapped in the interstices of the snow from which it has been derived. through the general whitish mass, at some places, innumerable parallel veins of clearer ice are drawn, which usually present a beautiful blue colour, and give the ice a laminated appearance. the cause of the blueness is, that the air-bubbles, distributed so plentifully through the general mass, do not exist in the veins, or only in comparatively small numbers. in different glaciers, and in different parts of the same glacier, these veins display various degrees of perfection. on the clean unweathered walls of some crevasses, and in the channels worn in the ice by glacier-streams, they are most distinctly seen, and are often exquisitely beautiful. they are not to be regarded as a partial phenomenon, or as affecting the constitution of glaciers to a small extent merely. a large portion of the ice of some glaciers is thus affected. the greater part, for example, of the mer de glace consists of this laminated ice; and the whole of the glacier of the rhone, from the base of the ice-cascade downwards, is composed of ice of the same description. [sidenote: grooves on the surface of glaciers.] those who have ascended snowdon, or wandered among the hills of cumberland, or even walked in the environs of leeds, blackburn, and other towns in yorkshire and lancashire, where the stratified sandstone of the district is used for building purposes, may have observed the weathered edges of the slate rocks or of the building-stone to be grooved and furrowed. some laminæ of such rocks withstand the action of the atmosphere better than others, and the more resistant ones stand out in ridges after the softer parts between them have been eaten away. an effect exactly similar is observed where the laminated ice of glaciers is exposed to the action of the sun and air. little grooves and ridges are formed upon its surface, the more resistant plates protruding after the softer material between them has been melted away. one consequence of this furrowing is, that the light dirt scattered by the winds over the surface of the glacier is gradually washed into the little grooves, thus forming fine lines resembling those produced by the passage of a rake over a sanded walk. these lines are a valuable index to some of the phenomena of motion. from a position on the ice of the glacier du géant a little higher up than trélaporte a fine view of these superficial groovings is obtained; but the dirt-lines are not always straight. a slight power of independent motion is enjoyed by the separate parts into which a glacier is divided by its crevasses and dislocations, and hence it is, that, at the place alluded to, the dirt-lines are bent hither and thither, though the ruptures of continuity are too small to affect materially the general direction of the structure. on the glacier of the talèfre i found these groovings useful as indicating the character of the forces to which the ice near the summit of the fall is subjected. the ridges between the chasms are in many cases violently bent and twisted, while the adjacent groovings enable us to see the normal position of the mass. [sidenote: guyot's observations.] the veined structure has been observed by different travellers; but it was probably first referred to by sir david brewster, who noticed the veins of the mer de glace on the th of september, . it was also observed by general sabine,[a] by rendu, by agassiz, and no doubt by many others; but the first clear description of it was given by m. guyot, in a communication presented to the geological society of france in . i quote the following passage from this paper:--"i saw under my feet the surface of the entire glacier covered with regular furrows from one to two inches wide, hollowed out in a half snowy mass, and separated by protruding plates of harder and more transparent ice. it was evident that the mass of the glacier here was composed of two sorts of ice, one that of the furrows, snowy and more easily melted; the other that of the plates, more perfect, crystalline, glassy, and resistant; and that the unequal resistance which the two kinds of ice presented to the atmosphere was the cause of the furrows and ridges. after having followed them for several hundreds of yards, i reached a fissure twenty or thirty feet wide, which, as it cut the plates and furrows at right angles, exposed the interior of the glacier to a depth of thirty or forty feet, and gave a beautiful transverse section of the structure. as far as my vision could reach i saw the mass of the glacier composed of layers of snowy ice, each two of which were separated by one of the plates of which i have spoken, the whole forming a regularly laminated mass, which resembled certain calcareous slates." [sidenote: forbes's researches.] previous observers had mistaken the lamination for stratification; but m. guyot not only clearly saw that they were different, but in the comparison which he makes he touches, i believe, on the true cause of the glacier-structure. he did not hazard an explanation of the phenomenon, and i believe his memoir remained unprinted. in the structure was noticed by professor forbes during his visit to m. agassiz on the lower aar glacier, and described in a communication presented by him to the royal society of edinburgh. he subsequently devoted much time to the subject, and his great merit in connexion with it consists in the significance which he ascribed to the phenomenon when he first observed it, and in the fact of his having proved it to be a constitutional feature of glaciers in general. [sidenote: forbes's theory.] the first explanation given of those veins by professor forbes was, that they were small fissures formed in the ice by its motion; that these were filled with the water of the melted ice in summer, which froze in winter so as to form the blue veins. this is the explanation given in his 'travels,' page ; and in a letter published in the 'edinburgh new philosophical journal,' october, , it is re-affirmed in these words:--"with the abundance of blue bands before us in the direction in which the differential motion must take place (in this case sensibly parallel to the sides of the glacier), it is impossible to doubt that these infiltrated crevices (for such they undoubtedly are) have this origin." this theory was examined by mr. huxley and myself in our joint paper; but it has been since alleged that ours was unnecessary labour, prof. forbes himself having in his thirteenth letter renounced the theory, and substituted another in its place. the latter theory differs, so far as i can understand it, from the former in this particular, that the _freezing of the water_ in the fissures is discarded, their sides being now supposed to be united "by the simple effects of time and cohesion."[b] for a statement of the change which his opinions have undergone, i would refer to the prefatory note which precedes the volume of 'occasional papers' recently published by prof. forbes; but it would have diminished my difficulty had the author given, in connexion with his new volume, a more distinct statement of his present views regarding the veined structure. with many of his observations and remarks i should agree; with many others i cannot say whether i agree or not; and there are others still with which i do not think i should agree: but in hardly any case am i certain of his precise views, excepting, indeed, the cardinal one, wherein he and others agree in ascribing to the structure a different origin from stratification. thus circumstanced, my proper course, i think, will be to state what i believe to be the cause of the structure, and leave it to the reader to decide how far our views harmonize; or to what extent either of them is a true interpretation of nature. [sidenote: usual aspect of blue veins.] most of the earlier observers considered the structure to be due to the stratification of the mountain-snows--a view which has received later development at the hands of mr. john ball; and the practical difficulty of distinguishing the undoubted effects of _stratification_ from the phenomena presented by _structure_, entitles this view to the fullest consideration. the blue veins of glaciers are, however, not always, nor even generally, such as we should expect to result from stratification. the latter would furnish us with distinct planes extending parallel to each other for considerable distances through the glacier; but this, though sometimes the case, is by no means the general character of the structure. we observe blue streaks, from a few inches to several feet in length, upon the walls of the same crevasse, and varying from the fraction of an inch to several inches in thickness. in some cases the streaks are definitely bounded, giving rise to an appearance resembling the section of a lens, and hence called the "lenticular structure" by mr. huxley and myself; but more usually they fade away in pale washy streaks through the general mass of the whitish ice. in fig. i have given a representation of the structure as it is very commonly exhibited on the walls of crevasses. its aspect is not that which we should expect from the consolidation of successive beds of mountain snow. [illustration: fig. . veined structure of the walls of crevasses.] further, at the bases of ice-cascades the structural laminæ are usually _vertical_: below the cascade of the talèfre, of the noire, of the strahleck branch of the lower grindelwald glacier, of the rhone, and other ice-falls, this is the case; and it seems extremely difficult to conceive that a mass horizontally stratified at the summit of the fall, should, in its descent, contrive to turn its strata perfectly on end. again, we often find a very feebly-developed structure at the central portions of a glacier, while the lateral portions are very decidedly laminated. this is the case where the inclination of the glacier is nearly uniform throughout; and where no medial moraines occur to complicate the phenomenon. but if the veins mark the bedding, there seems to be no sufficient reason for their appearance at the lateral portions of the glacier, and their absence from the centre. [sidenote: illustrative experiments.] this leads me to the point at which what i consider to be the true cause of the structure may be referred to. the theoretic researches of mr. hopkins have taught us a good deal regarding the pressures and tensions consequent upon glacier-motion. aided by this knowledge, and also by a mode of experiment first introduced by professor forbes, i will now endeavour to explain the significance of the fact referred to in the last paragraph. if a plastic substance, such as mud, flow down a sloping canal, the lateral portions, being held back by friction, will be outstripped by the central ones. when the flow is so regulated that the velocity of a point at the centre shall not vary throughout the entire length of the canal, a coloured circle stamped upon the centre of the mud stream, near its origin, will move along with the mud, and still retain its circular form; for, inasmuch as the velocity of all points along the centre is the same, there can be no elongation of the circle longitudinally or transversely by either strain or pressure. a similar absence of longitudinal pressure may exist in a glacier, and, where it exists throughout, no central structure can, in my opinion, be developed. but let a circle be stamped upon the mud-stream near its side, then, when the mud flows, this circle will be distorted to an oval, with its major axis oblique to the direction of motion; the cause of this is that the portion of the circle farthest from the side of the canal moves more freely than that adjacent to the side. the mechanical effect of the slower lateral motion is to squeeze the circle in one direction, and draw it out in the perpendicular one. [sidenote: marginal structure.] [illustration: fig. . figure explanatory of the marginal structure.] a glance at fig. will render all that i have said intelligible. the three circles are first stamped on the mud in the same transverse line; but after they have moved downwards they will be in the same straight line no longer. the central one will be the foremost; while the lateral ones have their forms changed from circles to ovals. in a glacier of the shape of this canal exactly similar effects are produced. now the shorter axis _m n_ of each oval is a line of squeezing or pressure; the longer axis is a line of strain or tension; and the associated glacier-phenomena are as follows:--across the line _m n_, or perpendicular to the pressure, we have the _veined structure_ developed, while across the line of tension the glacier usually breaks and forms _marginal crevasses_. mr. hopkins has shown that the lines of greatest pressure and of greatest strain are at right angles to each other, and that in valleys of a uniform width they enclose an angle of forty-five degrees with the side of the glacier. to the structure thus formed i have applied the term _marginal structure_. here, then, we see that there are mechanical agencies at work near the side of such a glacier which are absent from the centre, and we have effects developed--i believe _by the pressure_--in the lateral ice, which are not produced in the central. i have used the term "uniform inclination" in connexion with the marginal structure, and my reason for doing so will now appear. in many glaciers the structure, instead of being confined to the margins, sweeps quite across them. this is the case, for example, on the glacier du géant, the structure of which is prolonged into the mer de glace. in passing the strait at trélaporte, however, the curves are squeezed and their apices bruised, so that the structure is thrown into a state of confusion; and thus upon the mer de glace we encounter difficulty in tracing it fairly from side to side. now the key to this transverse structure i believe to be the following: where the inclination of the glacier suddenly changes from a steep slope to a gentler, as at the bases of the "cascades,"--the ice to a certain depth must be thrown into a state of violent longitudinal compression; and along with this we have the resistance which the gentler slope throws athwart the ice descending from the steep one. at such places a structure is developed transverse to the axis of the glacier, and likewise transverse to the pressure. the quicker flow of the centre causes this structure to bend more and more, and after a time it sweeps in vast curves across the entire glacier. [sidenote: structure of grindelwald glacier.] in illustration of this point i will refer, in the first place, to that tributary of the lower glacier of grindelwald which descends from the strahleck. walking up this tributary we come at length to the base of an ice-fall. let the observer here leave the ice, and betake himself to either side of the flanking mountain. on attaining a point which commands a view both of the fall and of the glacier below it, an inspection of the glacier will, i imagine, solve to his satisfaction the case of structure now under consideration. it is indeed a grand experiment which nature here submits to our inspection. the glacier descending from its _névé_ reaches the summit of the cascade, and is broken transversely as it crosses the brow; it afterwards descends the fall in a succession of cliffy ice-ridges with transverse hollows between them. in these latter the broken ice and débris collect, thus partially choking the fissures formed in the first instance. carrying the eye downwards along the fall, we see, as we approach the base, these sharp ridges toned down; and a little below the base they dwindle into rounded protuberances which sweep in curves quite across the glacier. at the base of the fall the structure begins to appear, feebly at first, but becoming gradually more pronounced, until, at a short distance below the base of the fall, the eye can follow the fine superficial groovings from side to side; while at the same time the ice underneath the surface has become laminated in the most beautiful manner. it is difficult to convey by writing the force of the evidence which the actual observation of this natural experiment places before the mind. the ice at the base of the fall, retarded by the gentler inclination of the valley, has to bear the thrust of the descending mass, the sudden change of inclination producing powerful longitudinal compression. the protuberances are squeezed more closely together, the hollows between them appear to wrinkle up in submission to the pressure--in short, the entire aspect of the glacier suggests the powerful operations of the latter force. at the place where _it_ is exerted the veined structure makes its appearance; and being once formed, it moves downwards, and gives a character to other portions of the glacier which had no share in its formation. [sidenote: base of cascade a "structure-mill."] an illustration almost as good, and equally accessible, is furnished by the glacier of the rhone. i have examined the grand cascade of this glacier from both sides; and an ordinary mountaineer will find little difficulty in reaching a point from which the fall and the terminal portion of the glacier are both distinctly visible. here also he will find the cliffy ridges separated from each other by transverse chasms, becoming more and more subdued at the bottom of the fall, and disappearing entirely lower down the glacier. as in the case of the grindelwald glacier the squeezing of the protuberances and of the spaces between them, is quite apparent, and where this squeezing commences the transverse structure makes its appearance. all the ice that forms the lower portion of this glacier has to pass through the _structure-mill_ at the bottom of the fall, and the consequence is that _it is all laminated_. [sidenote: structure of rhone glacier.] [illustration: fig. . plan of part of ice-fall, and of glacier below it (glacier of the rhone).] [illustration: fig. . section of part of ice-fall, and of glacier below it (glacier of the rhone).] [sidenote: transverse structure.] this case of structural development will be better appreciated on reference to figs. and , the former of which is a plan, and the latter a section, of a part of the ice-fall and of the glacier below it; _a b e f_ is the gorge of the fall, _f b_ being the base. the transverse cliffy ice-ridges are shown crossing the cascade, being subdued at the base to protuberances which gradually disappear as they advance downwards. the structure sweeps over the glacier in the direction of the fine curved lines; and i have also endeavoured to show the direction of the radial crevasses, which, in the centre at least, are at right angles to the veins. to the manifestation of structure here considered i have, for the sake of convenient reference, applied the term _transverse structure_. a third exhibition of the structure is now to be noticed. we sometimes find it in the _middle_ of a glacier and running _parallel_ to its length. on the centre of the ice-fall of the talèfre, for example, we have a structure of this kind which preserves itself parallel to the axis of the fall from top to bottom. but we discover its origin higher up. the structure here has been produced at the extremity of the jardin, where the divided ice meets, and not only brings into partial parallelism the veins previously existing along the sides of the jardin, but develops them still further by the mutual pressure of the portions of newly welded ice. where two tributary glaciers unite, this is perhaps without exception the case. underneath the moraine formed by the junction of the talèfre and léchaud the structure is finely developed, and the veins run in the direction of the moraine. the same is true of the ice under the moraine formed by the junction of the léchaud and géant. these afterwards form the great medial moraines of the mer de glace, and hence the structure of the trunk-stream underneath these moraines is parallel to the direction of the glacier. this is also true of the system of moraines formed by the glaciers of monte rosa. it is true in an especial manner of the lower glacier of the aar, whose medial moraine perhaps attains grander proportions than any other in the alps, and underneath which the structure is finely developed. [sidenote: longitudinal structure.] [illustration: fig. . figure explanatory of longitudinal structure.] the manner in which i have illustrated the production of this structure will be understood from fig. . b b are two wooden boxes, communicating by sluice-fronts with two branch canals, which unite to a common trunk at g. they are intended to represent respectively the trunk and tributaries of the unteraar glacier, the part g being the abschwung, where the lauteraar and finsteraar glaciers unite to form the unteraar. the mud is first permitted to flow beneath the two sluices until it has covered the bottom of the trough for some distance, when it is arrested. the end of a glass tube is then dipped into a mixture of rouge and water, and small circles are stamped upon the mud. the two branches are thickly covered with these circles. the sluices being again raised, the mud in the branches moves downwards, carrying with it the circles stamped upon it; and the manner in which these circles are distorted enables us to infer the strains and pressures to which the mud is subjected during its descent. the figure represents approximately what takes place. the side-circles, as might be expected, are squeezed to oblique ovals, but it is at the junction of the branches that the chief effect of pressure is produced. here, by the mutual thrust of the branches, the circles are not only changed to elongated ellipses, but even squeezed to straight lines. in the case of the glacier this is the region at which the structure receives its main development. to this manifestation of the veins i have applied the term _longitudinal structure_. the three main sources of the blue veins are, i think, here noted; but besides these there are many local causes which influence their production. i have seen them well formed where a glacier is opposed by the sudden bend of a valley, or by a local promontory which presents an obstacle sufficient to bring the requisite pressure into play. in the glaciers of the tyrol and of the oberland i have seen examples of this kind; but the three principal sources of the veins are, i think, those stated above. [sidenote: efforts to solve question.] it was long before i cleared my mind of doubt regarding the origin of the lamination. when on the mer de glace in i spared neither risk nor labour to instruct myself regarding it. i explored the talèfre basin, its cascade, and the ice beneath it. several days were spent amid the ice humps and cliffs at the lower portion of the fall. i suppose i traversed the glacier du géant twenty times, and passed eight or ten days amid the confusion of its great cascade. i visited those places where, it had been affirmed, the veins were produced. i endeavoured to satisfy myself of the mutability which had been ascribed to them; but a close examination reduced the value of each particular case so much that i quitted the glacier that year with nothing more than an _opinion_ that the structure and the stratification were two different things. i, however, drew up a statement of the facts observed, with the view of presenting it to the royal society; but i afterwards felt that in thus acting i should merely swell the literature of the subject without adding anything certain. i therefore withheld the paper, and resolved to devote another year to a search among the chief glaciers of the oberland, of the canton valais, and of savoy, for proofs which should relieve my mind of all doubt upon the subject. [sidenote: expedition for this purpose.] accordingly in i visited the glaciers of rosenlaui, schwartzwald, grindelwald, the aar, the rhone, and the aletsch, to the examination of which latter i devoted more than a week. i afterwards went to zermatt, and, taking up my quarters at the riffelberg, devoted eleven days to the examination of the great system of glaciers of monte rosa. i explored the görner glacier up almost to the cima de jazzi; and believed that in it i could trace the structure from portions of the glacier where it vanished, through various stages of perfection, up to its full development. i believe this still; but yet it is nothing but a belief, which the utmost labour that i could bestow did not raise to a certainty. the western glacier of monte rosa, the schwartze glacier, the trifti glacier, the glacier of the little mont cervin, and of st. théodule, were all examined in connexion with the great trunk-stream of the görner, to which they weld themselves; and though the more i pursued the subject the stronger my conviction became that pressure was the cause of the structure, a crucial case was still wanting. in the phenomena of slaty cleavage, it is often, if not usually, found that the true cleavage _cuts_ the planes of stratification--sometimes at a very high angle. had this not been proved by the observations of sedgwick and others, geologists would not have been able to conclude that cleavage and bedding were two different things, and needed wholly different explanations. my aim, throughout the expedition of , was to discover in the ice a parallel case to the above; to find a clear and undoubted instance where the veins and the stratification were simultaneously exhibited, cutting each other at an unmistakable angle. on the th of august, while engaged with professor ramsay upon the great aletsch glacier, not far from its junction with the middle aletsch, i observed what appeared to me to be the lines of bedding running nearly horizontal along the wall of a great crevasse, while cutting them at a large angle was the true veined structure. i drew my friend's attention to the fact, and to him it appeared perfectly conclusive. it is from a sketch made by him at the place that fig. has been taken. [sidenote: case of structure on the aletsch.] [illustration: fig. . structure and bedding on the great aletsch glacier.] this was the only case of the kind which i observed upon the aletsch glacier; and as i afterwards spent day after day upon the monte rosa glaciers, vainly seeking a similar instance, the thought again haunted me that we might have been mistaken upon the aletsch. in this state of mind i remained until the th of august, a day devoted to the examination of the furgge glacier, which lies at the base of the mont cervin. [sidenote: structure of the furgge glacier.] crossing the valley of the görner glacier, and taking a plunge as i passed into the schwarze see, i reached, in good time, the object of my day's excursion. walking up the glacier, i at length found myself opposed by a frozen cascade composed of four high terraces of ice. the highest of these was chiefly composed of ice-cliffs and _séracs_, many of which had fallen, and now stood like rocking-stones upon the edge of the second terrace. the glacier at the base of the cascade was strewn with broken ice, and some blocks two hundred cubic feet in volume had been cast to a considerable distance down the glacier. upon the faces of the terraces the stratification of the _névé_ was most beautifully shown, running in parallel and horizontal lines along the weathered surface. the snow-field above the cascade is a frozen plain, smooth almost as a sheltered lake. the successive snow-falls deposit themselves with great regularity, and at the summit of the cascade the sections of the _névé_ are for the first time exposed. hence their peculiar beauty and definition. [sidenote: ice terrace examined.] indeed the figure of a lake pouring itself over a rocky barrier which curves convexly upwards, thus causing the water to fall down it, not only longitudinally over the vertex of the curve, but laterally over its two arms, will convey a tolerably correct conception of the shape of the fall. towards the centre the ice was powerfully squeezed laterally, the beds were bent, and their continuity often broken by faults. on inspecting the ice from a distance with my opera glass, i thought i saw structural groovings cutting the strata at almost a right angle. had the question been an undisputed one, i should perhaps have felt so sure of this as not to incur the danger of pushing the inquiry further; but, under the circumstances, danger was a secondary point. resigning, therefore, my glass to my guide, who was to watch the tottering blocks overhead, and give me warning should they move, i advanced to the base of the fall, removed with my hatchet the weathered surface of the ice, and found underneath it the true veined structure, cutting, at nearly a right angle, the planes of stratification. the superficial groovings were not uniformly distributed over the fall, but appeared most decided at those places where the ice appeared to have been most squeezed. i examined three or four of these places, and in each case found the true veins nearly vertical, while the bedding was horizontal. having perfectly satisfied myself of these facts, i made a speedy retreat, for the ice-blocks seemed most threatening, and the sunny hour was that at which they fall most frequently. i next tried the ascent of the glacier up a dislocated declivity to the right. the ice was much riven, but still practicable. my way for a time lay amid fissures which exposed magnificent sections, and every step i took added further demonstration to what i had observed below. the strata were perfectly distinct, the structure equally so, and one crossed the other at an angle of seventy or eighty degrees. mr. sorby has adduced a case of the crumpling of a bed of sandstone through which the cleavage passes: here on the glacier i had parallel cases; the beds were bent and crumpled, but the structure ran through the ice in sharp straight lines. this perhaps was the most pleasant day i ever spent upon the glaciers: my mind was relieved of a long brooding doubt, and the intellectual freedom thus obtained added a subjective grandeur to the noble scene before me. climbing the cliffs near the base of the matterhorn, i walked along the rocky spine which extends to the hörnli, and afterwards descended by the valley of zmutt to zermatt. a year after my return to england a remark contained in professor mousson's interesting little work 'die gletscher der jetzzeit' caused me to refer to the atlas of m. agassiz's 'système glaciaire,' from which i learned that this indefatigable observer had figured a case of stratification and structure cutting each other. if, however, i had seen this figure beforehand, it would not have changed my movements; for the case, as sketched, would not have convinced me. i have now no doubt that m. agassiz has preceded me in this observation, and hence my results are to be taken as mere confirmations of his. [sidenote: lamination and stratification.] fig. represents a crumpled portion of the ice with the lines of lamination passing through the strata. fig. represents a case where a fault had occurred, the veins at both sides of the line of dislocation being inclined towards each other. [illustration: fig. . structure and stratification on the furgge glacier.] [illustration: fig. . structure and stratification on the furgge glacier.] [figs. and are from sketches made on the furgge glacier.--l. c. t.] footnotes: [a] in reply to a question in connexion with this subject, general sabine has favoured me with the following note:-- "my dear tyndall, "it was in the summer of , at the lower grindelwald glacier, that i first saw, and was greatly impressed and interested by examining and endeavouring to understand (in which i did not succeed), the veined structure of the ice. i do not remember when i mentioned it to forbes, but it must be before , because it is noticed in his book, p. . i had never observed it in the glaciers of spitzbergen or baffin's bay, or in the icebergs of the shores and straits of davis or barrow. i feel the more confident of this, because, when i first saw the veined structure in switzerland, my arctic experience was more fresh in my recollection, and i recollected nothing like it. "_veins_ are indeed not uncommon in icebergs, but they quite resemble veins in rocks, and are formed by water filling fissures and freezing into blue ice, finely contrasted with the white granular substance of the berg. "the ice of the grindelwald glacier (where i examined the veined structure) was broken up into very large masses, which by pressure had been upturned, so that a very poor judgment would be formed of the direction of the veins as they existed in the glacier before it had broken up. "sincerely yours, "edward sabine. "_feb. , _." [b] in a letter to myself, published in the th volume of the 'philosophical magazine,' professor forbes writes as follows:--"in , then, i abandoned no part of the theory of the veined structure, on which as you say so much labour had been expended, except the admission, always yielded with reluctance, and got rid of with satisfaction, that the congelation of water in the crevices of the glacier may extend in winter to a great depth." the veined structure and the differential motion. ( .) [sidenote: differential motion greatest at edges.] i have now to examine briefly the explanation of the structure which refers it to differential motion--to a sliding of the particles of ice past each other, which leaves the traces of its existence in the blue veins. the fact is emphatically dwelt upon by those who hold this view, that the structure is best developed nearest to the sides of the glacier, where the differential motion is greatest. why the differential motion is at its maximum near to the sides is easily understood. let a b, c d, fig. , represent the two sides of a glacier, moving in the direction of the arrow, and let _m a b c n_ be a straight line of stakes set out across the glacier to-day. six months hence this line, by the motion of the ice downwards, will be bent to the form _m a' b' c' n_: this curve will not be circular, it will be flattened in the middle; the points _a_ and _c_, at some distance on each side of the centre _b_, move in fact with nearly the same velocity as the centre itself. not so with the sides:--_a'_ and _c'_ have moved considerably in advance of _m_ and _n_, and hence we say that the difference of motion, or the differential motion, of the particles of ice near to the side is a maximum. [illustration: fig. . diagram illustrating differential motion.] during all this time the points _m a' b' c' n_ have been moving straight down the glacier; and hence it will be understood that the sliding of the parts past each other, or, in other words, the differential motion, _is parallel to the sides of the glacier_. this, indeed, is the only differential motion that experiment has ever established; and consequently, when we find the best blue veins referred to the sides of the glacier because the differential motion is there greatest, we naturally infer that the motion meant is parallel to the sides. [sidenote: structure oblique to sides.] but the fact is, that this motion would not at all account for the blue veins, for they are not parallel to the sides, but _oblique_ to them. this difficulty revealed itself after a time to those who first propounded the theory of differential motion, and caused them to modify their explanation of the structure. differential motion is still assumed to be the cause of the veins, but now a motion is meant oblique to the sides, and it is supposed to be obtained in the following way:--through the quicker motion of the point _c'_ the ice between it and _n_ becomes distended; that is to say, the line _c' n_ is in a state of strain--there is a _drag_, it is said, oblique to the sides of the glacier; and it is therefore in this direction that the particles will be caused to slide past each other. dr. whewell, who advocates this view, thus expounds it. he supposes the case of an alpine valley filled with india-rubber which has been warmed until it has partially melted, or become viscous, and then asks, "what will now be the condition of the mass? the sides and bottom will still be held back by the friction; the middle and upper part will slide forwards, but not freely. this want of freedom in the motion (arising from the viscosity) will produce a drag towards the middle of the valley, where the motion is freest; hence the direction in which the filaments slide past each other will be obliquely directed towards the middle. the sliding will separate the mass according to such lines; and though new attachments will take place, the mass may be expected to retain the results of this separation in the traces of parallel fissures."[a] nothing can be clearer than the image of the process thus placed before the mind's eye. one fact of especial importance is to be borne in mind: the sliding of filaments which is thus supposed to take place oblique to the glacier has never been proved; it is wholly assumed. a moraine, it is admitted, will run parallel to the side of a glacier, or a block will move in the same direction from beginning to end, without being sensibly drawn towards the centre, but still it is supposed that the sliding of parts exists, though of a character so small as to render it insensible to measurement. [sidenote: structure crosses lines of sliding.] my chief difficulty as regards this theory may be expressed in a very few words. if the structure be produced by differential motion, why is the large and _real_ differential motion which experiments have established incompetent to produce it? and how can the veins run, as they are admitted to do, _across the lines of maximum sliding_ from their origin throughout the glacier to its end? that a drag towards the centre of the glacier exists is undeniable, but that in consequence of the drag there is a sliding of filaments in this direction, is quite another thing. i have in another place[b] endeavoured to show experimentally that no such sliding takes place, that the drag on any point towards the centre expresses only half the conditions of the problem; being exactly neutralized by the thrust towards the sides. it has been, moreover, shown by mr. hopkins that the lines of maximum strain and of maximum sliding cannot coincide; indeed, if all the particles be urged by the same force, no matter how strong the pull may be, there will be no tendency of one to slide past the other. footnotes: [a] 'philosophical magazine,' ser. iii., vol. xxvi. [b] 'proceedings of the royal institution,' vol. ii. p. . the ripple-theory of the veined structure. ( .) [sidenote: theory stated.] [sidenote: theory examined.] the assumption of oblique sliding, and the production thereby of the marginal structure, have, however, been fortified by considerations of an ingenious and very interesting kind. "how," i have asked, "can the oblique structure persist across the lines of greatest differential motion throughout the length of the glacier?" but here i am met by another question which at first sight might seem equally unanswerable--"how do ripple-marks on the surface of a flowing river, which are nothing else than lines of differential motion of a low order, cross the river from the sides obliquely, while the direction of greatest differential motion is parallel to the sides?" if i understand aright, this is the main argument of professor forbes in favour of his theory of the oblique marginal structure. it is first introduced in a note at page of his 'travels;' he alludes to it in a letter written the following year; in his paper in the 'philosophical transactions' he develops the theory. he there gives drawings of ripple-marks observed in smooth gutters after rain, and which he finds to be inclined to the course of the stream, exactly as the marginal structure is inclined to the side of the glacier. the explanation also embraces the case of an obstacle placed in the centre of a river. "a case," writes professor forbes, "parallel to the last mentioned, where a fixed obstacle cleaves a descending stream, and leaves its trace in a fan-shaped tail, is well known in several glaciers, as in that at ferpêcle, and the glacier de lys on the south side of monte rosa; particularly the last, where the veined structure follows the law just mentioned." in his twelfth letter he also refers to the ripples "as exactly corresponding to the position of the icy bands." in his letter to dr. whewell, published in the 'occasional papers,' page , he writes as follows:--"the same is remarkably shown in the case of a stream of water, for instance a mill-race. although the movement of the water, as shown by floating bodies, is exceedingly nearly (for small velocities sensibly) parallel to the sides, yet the variation of the speed from the side to the centre of the stream occasions a _ripple_, or molecular discontinuity, which inclines forwards from the sides to the centre of the stream at an angle with the axis depending on the ratio of the central and lateral velocity. the veined structure of the ice corresponds to the ripple of the water, a molecular discontinuity whose measure is not comparable to the actual velocity of the ice; and therefore the general movement of the glacier, as indicated by the moraines, remains sensibly parallel to the sides." this theory opens up to us a series of interesting and novel considerations which i think will repay the reader's attention. if the ripples in the water and the veins in the ice be due to the same mechanical cause, when we develop clearly the origin of the former we are led directly to the explanation of the latter. i shall now endeavour to reduce the ripples to their mechanical elements. the messrs. weber have described in their 'wellenlehre' an effect of wave-motion which it is very easy to obtain. when a boat moves through perfectly smooth water, and the rower raises his oar out of the water, drops trickle from its blade, and each drop where it falls produces a system of concentric rings. the circular waves as they widen become depressed, and, if the drops succeed each other with sufficient speed, the rings cross each other at innumerable points. the effect of this is to blot out more or less completely all the circles, and to leave behind two straight divergent ripple-lines, which are tangents to all the external rings; being in fact formed by the intersections of the latter, as a caustic in optics is formed by the intersection of luminous rays. fig. , which is virtually copied from m. weber, will render this description at once intelligible. the boat is supposed to move in the direction of the arrow, and as it does so the rings which it leaves behind widen, and produce the divergence of the two straight resultant lines of ripple. [sidenote: ripples deduced from rings.] [illustration: fig. . diagram explanatory of the formation of ripples.] the more quickly the drops succeed each other, the more frequent will be the intersections of the rings; but as the speed of succession augments we approach the case of _a continuous vein_ of liquid; and if we suppose the continuity to be perfectly established, the ripples will still be produced with a smooth space between them as before. this experiment may indeed be made with a well-wetted oar, which on its first emergence from the water sends into it a continuous liquid vein. the same effect is produced when we substitute for the stream of liquid a solid rod--a common walking-stick for example. a water-fowl swimming in calm water produces two divergent lines of ripples of a similar kind. we have here supposed the water of the lake to be at rest, and the liquid vein or the solid rod to move through it; but precisely the same effect is produced if we suppose the rod at rest and the liquid in motion. let a post, for example, be fixed in the middle of a flowing river; diverging from that post right and left we shall have lines of ripples exactly as if the liquid were at rest and the post moved through it with the velocity of the river. if the same post be placed close to the bank, so that _one_ of its edges only shall act upon the water, diverging from that edge we shall have a _single_ line of ripples which will cross the river obliquely towards its centre. it is manifest that any other obstacle will produce the same effect as our hypothetical post. in the words of professor forbes, "the slightest prominence of any kind in the wall of such a conduit, a bit of wood or a tuft of grass, is sufficient to produce a well-marked ripple-streak from the side towards the centre." [sidenote: measure of divergence of ripples.] the foregoing considerations show that the divergence of the two lines of ripples from the central post, and of the single line in the case of the lateral post, have their mechanical element, if i may use the term, in the experiment of the messrs. weber. in the case of a swimming duck the connexion between the diverging lines of ripples and the propagation of rings round a disturbed point is often very prettily shown. when the creature swims with vigour the little foot with which it strikes the water often comes sufficiently near to the surface to produce an elevation,--sometimes indeed emerging from the water altogether. round the point thus disturbed rings are immediately propagated, and the widening of those rings is _the exact measure of the divergence of the ripple lines_. the rings never cross the lines;--the lines never retreat from the rings. [sidenote: ripples and veins due to different causes.] if we compare the mechanical actions here traced out with those which take place upon a glacier, i think it will be seen that the analogy between the ripples and the veined structure is entirely superficial. how the structure ascribed to the glacier de lys is to be explained i do not know, for i have never seen it; but it seems impossible that it could be produced, as ripples are, by a fixed obstacle which "cleaves a descending stream." no one surely will affirm that glacier-ice so closely resembles a fluid as to be capable of transmitting undulations, as water propagates rings round a disturbed point. the difficulty of such a supposition would be augmented by taking into account the motion of the _individual liquid particles_ which go to form a ripple; for the messrs. weber have shown that these move in closed curves, describing orbits more or less circular. can it be supposed that the particles of ice execute a motion of this kind? if so, their orbital motions may be easily calculated, being deducible from the motion of the glacier compounded with the inclination of the veins. if so important a result could be established, all glacier theories would vanish in comparison with it. [sidenote: position of ripples not that of structure.] there is another interesting point involved in the passage above quoted. professor forbes considers that the ripple is occasioned by the variation of speed from the side to the centre of the stream, and that its _inclination_ depends on the ratio of the central and lateral velocity. if i am correct in the above analysis, this cannot be the case. the inclination of the ripple depends solely on the ratio of the river's translatory motion to the velocity of its wave-motion. were the lateral and central velocities alike, a momentary disturbance at the side would produce a _straight_ ripple-mark, whose inclination would be compounded of the two elements just mentioned. if the motion of the water vary from side to centre, the velocity of wave-propagation remaining constant, the inclination of the ripple will also vary, that is to say, we shall have a _curved_ ripple instead of a straight one. this, of course, is the case which we find in nature, but the curvature of such ripples is totally different from that of the veined structure. owing to the quicker translatory movement, the ripples, as they approach the centre, tend more to parallelism with the direction of the river; and after having passed the centre, and reached the slower water near the opposite side, their inclination to the axis gradually augments. thus the ripples from the two sides form a pair of symmetric curves, which cross each other at the centre, and possess the form _a o b_, _c o d_, shown in fig. . a similar pair of curves would be produced by the reflection of these. knowing the variation of motion from side to centre, any competent mathematician could find the equation of the ripple-curves; but it would be out of place for me to attempt it here. [illustration: fig. . diagram explanatory of the formation of ripples.] the veined structure and pressure. ( .) if a prism of glass be pressed by a sufficient weight, the particles in the line of pressure will be squeezed more closely together, while those at right angles to this line will be forced further apart. the existence of this state of strain may be demonstrated by the action of such squeezed glass upon polarised light. it gives rise to colours, and it is even possible to infer from the tint the precise amount of pressure to which the glass is subjected. m. wertheim indeed has most ably applied these facts to the construction of a dynamometer, or instrument for measuring pressures, exceeding in accuracy any hitherto devised. when the pressure applied becomes too great for the glass to sustain, it flies to pieces. but let us suppose the sides of the prism defended by an extremely strong jacket, in which the prism rests like a closely-fitting plug, and which yields only when a pressure more than sufficient to crush the glass is applied. let the pressure be gradually augmented until this point is attained; afterwards both the glass and its jacket will shorten and widen; the jacket will yield laterally, being pushed out with extreme slowness by the glass within. [sidenote: possible experiment with glass prism.] now i believe that it would be possible to make this experiment in such a manner that the glass should be _flattened_, partly through rupture, and partly through lateral molecular yielding; the prism would change its form, and yet present a firmly coherent mass when removed from its jacket. i have never made the experiment; nobody has, as far as i know; but experiments of this kind are often made by nature. in the museum of the government school of mines, for example, we have a collection of quartz stones placed there by mr. salter, and which have been subjected to enormous pressure in the neighbourhood of a fault. these rigid pebbles have, in some cases, been squeezed against each other so as to produce mutual flattening and indentation. some of them have yielded along planes passing through them, as if one half had slidden over the other; but the reattachment is very strong. some of the larger stones, moreover, which have endured pressure at a particular point, are fissured radially around this point. in short, the whole collection is a most instructive example of the manner and extent to which one of the most rigid substances in nature can yield on the application of a sufficient force. [sidenote: possible experiment with prism of ice.] let a prism of ice at ° be placed in a similar jacket to that which we have supposed to envelop the glass prism. the ice yields to the pressure with incomparably greater ease than the glass; and if the force be slowly applied, the lateral yielding will far more closely resemble that of a truly plastic body. supposing such a piece of ice to be filled with numerous small air-bubbles, the tendency of the pressure would be to flatten these bubbles, and to squeeze them out of the ice. were the substance perfectly homogeneous, this flattening and expulsion would take place uniformly throughout its entire mass; but i believe there is no such homogeneous substance in nature;--the ice will yield at different places, leaving between them spaces which are comparatively unaffected by the pressure. from the former spaces the air-bubbles will be more effectually expelled; and i have no doubt that the result of such pressure acting upon ice so protected would be to produce a laminated structure somewhat similar to that which it produces in those bodies which exhibit slaty cleavage. [sidenote: lamination produced by pressure.] [sidenote: no sliding of filaments.] i also think it certain that, in this lateral displacement of the particles, these must move past each other. this is an idea which i have long entertained, as the following passage taken from the paper published by mr. huxley and myself will prove:--"three principal causes may operate in producing cleavage: first, the reducing of surfaces of weak cohesion to parallel planes; second, the flattening of minute cavities; and third, the weakening of cohesion by tangential action. the third action is exemplified by the state of the rails near a station where a break is habitually applied to a locomotive. in this case, while the weight of the train presses vertically, its motion tends to cause longitudinal sliding of the particles of the rail. tangential action does not, however, necessarily imply a force of the latter kind. when a solid cylinder an inch in height is squeezed to a vertical cake a quarter of an inch in height, it is impossible, physically speaking, that the particles situated in the same vertical line shall move laterally with the same velocity; but if they do not, the cohesion between them will be weakened or ruptured. the pressure, however, will produce new contact; and if this have a cohesive value equal to that of the old contact, no cleavage from this cause can arise. the relative capacities of different substances for cleavage appear to depend in a great measure upon their different properties in this respect. in butter, for example, the new attachments are equal, or nearly so, to the old, and the cleavage is consequently indistinct; in wax this does not appear to be the case, and hence may arise in a great degree the perfection of its cleavage. the further examination of this subject promises interesting results." i would dwell upon this point the more distinctly as the advocates of differential motion may deem it to be in their favour; but it appears to me that the mechanical conceptions implied in the above passage are totally different from theirs. if they think otherwise, then it seems to me that they should change the expressions which refer the differential motion to a "drag" towards the centre, and the structure to the sliding of "filaments" past each other in consequence of this drag. such filamentary sliding may take place in a truly viscous body, but it does not take place in ice. in one particular the ice resembles the butter referred to in the above quotation; for its new attachments appear to be equal to the old, and this, i think, is to be ascribed to its perfect regelation. as justly pointed out by mr. john ball, the veined ice of a glacier, if unweathered, shows no tendency to cleave; for though the expulsion of the air-bubbles has taken place, the reattachment of the particles is so firm as to abolish all evidence of cleavage. when the ice, on the contrary, is weathered, the plates become detached, and i have often been able to split such ice into thin tablets having an area of two or three square feet. in his thirteenth letter professor forbes throws out a new and possibly a pregnant thought in connexion with the veins. if i understand him aright--and i confess it is usually a matter of extreme difficulty with me to make sure of this--he there refers the veins, not to the expulsion of the air from the ice, but to its redistribution. the pressure produces "_lines of tearing_ in which the air is distributed in the form of regular globules." i do not know what might be made of this idea if it were developed, but at present i do not see how the supposed action could produce the blue bands; and i agree with professor wm. thomson in regarding the explanation as improbable.[a] footnotes: [a] for an extremely ingenious view of the origin of the veined structure, i would refer to a paper by professor thomson, in the 'proceedings of the royal society,' april, . the veined structure and the liquefaction of ice by pressure. ( .) i have already noticed an important fact for which we are indebted to mr. james thomson, and have referred to the original communications on the subject. i shall here place the physical circumstances connected with this fact before my reader in the manner which i deem most likely to interest him. [sidenote: influence of pressure on boiling point.] when a liquid is heated, the attraction of the molecules operates against the action of the heat, which tends to tear them asunder. at a certain point the force of heat triumphs, the cohesion is overcome, and the liquid boils. but supposing we assist the attraction of the molecules by applying an external pressure, the difficulty of tearing them asunder will be increased; more heat will be required for this purpose; and hence we say that the _boiling point_ of the liquid has been _elevated_ by the pressure. [sidenote: influence of pressure on fusing point.] if molten sulphur be poured into a bullet-mould, it will be found on cooling to contract, so as to leave a large hollow space in the middle of each sphere. cast musket-bullets are thus always found to possess a small cavity within them produced by the contraction of the lead. conceive the bullet placed within its mould and the latter heated; to produce fusion it is necessary that the sulphur or the lead should _swell_. here, as in the case of the heated water, the tendency to expand is opposed by the attraction of the molecules; with a certain amount of heat however this attraction is overcome and the solid _melts_. but suppose we assist the molecular attraction by a suitable force applied externally, a greater amount of heat than before will be necessary to tear them asunder; and hence we say that the _fusing point_ has been _elevated_ by the pressure. this fact has been experimentally established by messrs. hopkins and fairbairn, who applied to spermaceti and other substances pressures so great as to raise their points of fusion a considerable number of degrees. let us now consider the case of the metal bismuth. if the molten metal be poured into a bullet-mould it will _expand_ on solidifying. i have myself filled a strong cast-iron bottle with the metal, and found its expansion on cooling sufficiently great to split the bottle from neck to bottom. hence, in order to fuse the bismuth the substance must _contract_; and it is manifest that an external pressure which tends to squeeze the molecules more closely together here _assists_ the heat instead of opposing it. hence, to fuse bismuth under great pressure, a less amount of heat will be required than when the pressure is removed; or, in other words, the fusing point of bismuth is _lowered_ by the pressure. now, in passing from the solid to the liquid state, _ice_, like bismuth, contracts, and if the contraction be promoted by external pressure, as shown by the messrs. thomson, a less amount of heat suffices to liquefy it. [sidenote: experiments.] these remarks will enable us to understand a singular effect first obtained by myself at the close of or in january , noticed at the time in the 'proceedings of the royal society,' and afterwards fully described in a paper presented to the society in december of that year. a cylinder of clear ice two inches high and an inch in diameter was placed between two slabs of box-wood, and subjected to a gradual pressure. i watched the ice in a direction perpendicular to its length, and saw cloudy lines drawing themselves across it. as the pressure continued, these lines augmented in numbers, until finally the prism presented the appearance of a crystal of gypsum whose planes of cleavage had been forced out of optical contact. when looked at obliquely it was found that the lines were merely the sections of flat dim surfaces, which lay like laminæ one over the other throughout the length of the prism. fig. represents the prism as it appeared when looked at in a direction perpendicular to its axis; fig. shows the appearance when viewed obliquely.[a] [illustration: fig. , . appearance of a prism of ice partially liquefied by pressure.] at first sight it might appear as if air had intruded itself between the separated surfaces of the ice, and to test this point i placed a cylinder two inches long and an inch wide upright in a copper vessel which was filled with ice-cold water. the ice cylinder rose about half an inch above the surface of the water. placing the copper vessel on a slab of wood, and a second slab on the top of the cylinder of ice, the latter was subjected to the gradual action of a small hydraulic press. when the hazy surfaces were well developed in the portion of the ice above the water, the cylinder was removed and examined: the planes of rupture extended throughout the entire length of the cylinder, just as if it had been squeezed in air. i subsequently placed the ice in a stout vessel of glass, and squeezed it, as in the last experiment: the surfaces of discontinuity were seen forming _under the liquid_ quite as distinctly as in air. to prove that the surfaces were due to compression and not to any tearing asunder of the mass by tension, the following experiment was made:--a cylindrical piece of ice, one of whose ends, however, was not parallel to the other, was placed between the slabs of wood, and subjected to pressure. fig. shows the disposition of the experiment. the effect upon the ice cylinder was that shown in fig. , the surfaces being developed along that side which had suffered the pressure. on examining the surfaces by a pocket lens they resembled the effect produced upon a smooth cold surface by breathing on it. [illustration: fig. , . figures illustrative of compression and liquefaction of ice.] [sidenote: liquid layers produced by pressure.] the surfaces were always dim; and had the spaces been filled with air, or were they simply vacuous, the reflection of light from them would have been so copious as to render them much more brilliant than they were observed to be. to examine them more particularly i placed a concave mirror so as to throw the diffused daylight from a window full upon the cylinder. on applying the pressure dim spots were sometimes seen forming in the very middle of the ice, and these as they expanded laterally appeared to be in a state of intense motion, which followed closely the edge of each surface as it advanced through the solid ice. once or twice i observed the hazy surfaces pioneered through the mass by dim offshoots, apparently liquid, and constituting a kind of decrystallisation. from the closest examination to which i was able to subject them, the surfaces appeared to me to be due to internal liquefaction; indeed, when the melting point of ice, having already a temperature of °, is lowered by pressure, its excess of heat must instantly be applied to produce this effect. [sidenote: application to the veined structure.] i have already given a drawing (p. ) showing the development of the veined structure at the base of the ice-cascade of the rhone; and if we compare that diagram with fig. a striking similarity at once reveals itself. the ice of the glacier must undoubtedly be liquefied to some extent by the tremendous pressure to which it is here subjected. surfaces of discontinuity will in all probability be formed, which facilitate the escape of the imprisoned air. the small quantity of water produced will be partly imbibed by the adjacent porous ice, and will be refrozen when relieved from the pressure. this action, associated with that ascribed to pressure in the last section, appears to me to furnish a complete physical explanation of the laminated structure of glacier-ice. footnotes: [a] this effect projected upon a screen is a most striking and instructive class experiment. white ice-seams in the glacier du gÉant. ( .) [sidenote: general appearance of white ice-seams.] on the th of july, , while engaged upon the glacier du géant, my attention was often attracted by protuberant ridges of what at first appeared to be pure white snow, but which on examination i found to be compact ice filled with innumerable round air-cells; and which, in virtue of its greater power of resistance to wasting, often rose to a height of three or four feet above the general level of the ice. as i stood amongst these ridges, they appeared detached and without order of arrangement, but looked at from a distance they were seen to sweep across the proper glacier du géant in a direction concentric with its dirt-bands and its veined structure. in some cases the seams were admirable indications of the relative displacement of two adjacent portions of the glacier, which were divided from each other by a crevasse. usually the sections of a seam exposed on the opposite sides of a fissure accurately faced each other, and the direction of the seam on both sides was continuous; but at other places they demonstrated the existence of lateral faults, being shifted asunder laterally through spaces varying from a few inches to six or seven feet. on the following day i was again upon the same glacier, and noticed in many cases the white ice-seams exquisitely honeycombed. the case was illustrative of the great difference between the absorptive power of the ice itself and of the objects which lie upon its surface. deep cylindrical cells were produced by spots of black dirt which had been scattered upon the surface of the white ice, and which sank to a depth of several inches into the mass. i examined several sections of the veins, and in general i found that their deeper portions blended gradually with the ice on either side of them. but higher up the glacier i found that the veins penetrated only to a limited depth, and did not therefore form an integrant portion of the glacier. figs. and show the sections of two of the seams which were exposed on the wall of a crevasse at some distance below the great ice-fall of the glacier du géant. [sidenote: sections of seams.] [illustration: fig. , . sections of white ice-seams.] [illustration: fig. . variations in the dip of the veined structure.] it was at the base of the talèfre cascade that the explanation of these curious seams presented itself to me. in one of my earliest visits to this portion of the glacier i was struck by a singular disposition of the blue veins on the vertical wall of a crevasse. fig. will illustrate what i saw. the veins, within a short distance, dipped _backward_ and _forward_, like the junctions of stones used to turn an arch. in some cases i found this variation of the structure so great as to pass in a short distance from the vertical to the horizontal, as shown in fig. . [sidenote: variations in "dip" of structure.] [illustration: fig. . variations in the dip of the veined structure.] further examination taught me that the glacier here is crumpled in a most singular manner; doubtless by the great pressure to which it is exposed. the following illustration will convey a notion of its aspect: let one hand be laid flat upon a table, palm downwards, and let the fingers be bent until the space between the first joint and the ends of the fingers is vertical; one of the crumples to which i refer will then be represented. the ice seems bent like the fingers, and the crumples of the glacier are cut by crevasses, which are accurately typified by the spaces between the fingers. let the second hand now be placed upon the first, as the latter is upon the table, so that the tops of the bent fingers of the second hand shall rest upon the roots of the first: two crumples would thus be formed; a series of such protuberances, with steep fronts, follow each other from the base of the talèfre cascade for some distance downwards. on saturday the st of august i ascended these rounded terraces in succession, and observed among them an extremely remarkable disposition of the structure. fig. is a section of a series of three of the crumples, on which the shading lines represent the direction of the blue veins. at the base of each protuberance i found a seam of white ice wedged firmly into the glacier, and _each of the seams marked a place of dislocation of the veins_. the white seams thinned off gradually, and finally vanished where the violent crumpling of the ice disappeared. in fig. i have sketched the wall of a crevasse, which represents what may be regarded as the incipient crumpling. the undulating line shows the contour of the surface, and the shading lines the veins. it will be observed that the direction of the veins yields in conformity with the undulation of the surface; and an augmentation of the effect would evidently result in the crumples shown in fig. . the appearance of the white seams at those places where a dislocation occurred was, as far as i could observe, invariable; but in a few instances the seams were observed upon the platforms of the terraces, and also upon their slopes. the width of a seam was very irregular, varying from a few inches at some places to three or four feet at others. [sidenote: crumples of the talÈfre.] [illustration: fig. . section of three glacier crumples.] [illustration: fig. . wall of a crevasse, with incipient crumpling.] [sidenote: moulds of white ice-seams.] on the rd of august i was again at the base of the talèfre cascade, and observed a fact the significance of which had previously escaped me. the rills which ran down the ice-slopes collected at the base of each protuberance into a stream, which, at the time of my visit, had hollowed out for itself a deep channel in the ice. at some places the stream widened, at others its banks of ice approached each other, and rapids were produced; in fact, _the channels of such streams appeared to be the exact moulds of the seams of white ice_. instructed thus far, i ascended the glacier du géant on the th of august, and then observed on the wrinkles of this glacier the same leaning backwards and forwards of the blue veins as i had previously observed upon the talèfre. i also noticed on this day that a seam of white ice would sometimes open out into two branches, which, after remaining for some distance separate, would reunite and thus enclose a little glacier-island. at other places lateral branches were thrown off from the principal seam, thus suggesting the form of a glacier-rivulet which had been fed by tributary branches. on the th of august i hunted the seams still farther up the glacier; and found them at one place descending a steep ice-hill, being crossed by other similar bands, which however were far less white and compact. i followed these new bands to their origin, and found it to be a system of crevasses formed at the summit of the hill, some of which were filled with snow. lower down the crevasses closed, and the snow thus jammed between their walls was converted into white ice. these seams, however, never attained the compactness and prominence of the larger ones which had their origin far higher up. i singled out one of the best of the latter, and traced it through all the dislocation and confusion of the ice, until i found it to terminate in a cavity filled with snow. this was near the base of the _séracs_, and the streams here were abundant. comparing the shapes of some of them with that of the ice-bands lower down the glacier, a striking resemblance was observed. fig. is the plan of a deep-cut channel through which a stream flowed on the day to which i now refer. fig. is the plan of a seam of white ice sketched on the same day, low down upon the glacier. instances of this kind might be multiplied; and the result, i think, renders it certain that the white ice-seams referred to are due to the filling up of the channels of glacier-streams by snow during winter, and the subsequent compression of the mass to ice during the descent of the glacier. i have found such seams at the bases of all cascades that i have visited; and in all cases they appear to be due to the same cause. the depth to which they penetrate the glacier must be profound, or the _ablation_ of the ice must be less than what is generally supposed; for the seams formed so high up on the glacier du géant may be traced low down upon the trunk-stream of the mer de glace.[a] [sidenote: streams and seams.] [illustration: fig. . plan of a stream on the glacier du géant.] [illustration: fig. . plan of a seam of white ice on the glacier du géant.] [sidenote: scaling off by pressure.] these observations on the white ice-seams enable us to add an important supplement to what has been stated regarding the origin of the dirt-bands of the mer de glace; the protuberances at the base of the cascade are due not only to the toning down of the ridges produced by the transverse fracture of the glacier at the summit of the fall, but they undergo modifications by the pressure locally exerted at its base. the state of things represented in fig. is plainly due to the partial pushing of one crumple over that next in advance of it. there seems to be a differential motion of the parts of the glacier in the same longitudinal line; showing that upon the general motion of the glacier smaller local motions are superposed. the occurrence of the seams upon the faces of the slopes seems also to prove that the pressure is competent, in some cases, to cause the bases of the protuberances to swell, so that what was once the base of a crumple may subsequently form a portion of its slope. another interesting fact is also observed where the pressure is violent: the crumples _scale off_, bows of ice being thus formed which usually span the crumples over their most violently compressed portions. i have found this scaling off at the bases of all the cascades which i have visited, and it is plainly due to the pressure exerted at such places upon the ice. footnotes: [a] the more permanent seams may possibly be due to the filling of the profound crevasses of the cascade. ( .) [sidenote: compression of glacier du gÉant.] not only at the base of its great cascade, but throughout the greater part of its length, the glacier du géant is in a state of longitudinal compression. the meaning of this term will be readily understood: let two points, for example, be marked upon the axis of the glacier; if these during its descent were drawn wider apart, it would show that the glacier was in a state of longitudinal strain or tension; if they remained at the same distance apart, it would indicate that neither strain nor pressure was exerted; whereas, if the two points approached each other, which could only be by the quicker motion of the hinder one, the existence of longitudinal compression would be thereby demonstrated. taking "le petit balmat" with me, to carry my theodolite, i ascended the glacier du géant until i came near the place where it is joined by the glacier des périades, and whence i observed a patch of fresh green grass upon the otherwise rocky mountain-side. to this point i climbed, and made it the station for my instrument. choosing a well-defined object at the opposite side of the glacier, i set, on the th of august, in the line between this object and the theodolite, three stakes, one in the centre of the glacier, and the other two at opposite sides of the centre and about yards from it. this done, i descended for a quarter of a mile, when i again climbed the flanking rocks, placing my theodolite in a couloir, down which stones are frequently discharged from the end of a secondary glacier which hangs upon the heights above. here, as before, i fixed three stakes, chiselled a mark upon the granite, so as to enable me to find the place, and regained the ice without accident. a day or two previously we had set out a third line at some distance lower down, and i was thus furnished with a succession of points along the glacier, the relative motions of which would decide whether it was _pressed_ or _stretched_ in the direction of its length. on the th of august mr. huxley joined us; and on the following day we all set out for the glacier du géant, to measure the progress of the stakes which i had fixed there. hirst remained upon the glacier to measure the displacements; i shouldered the theodolite; and huxley was my guide to the mountain-side, sounding in advance of me the treacherous-looking snow over which we had to pass. calling the central stake of the highest line no. , that of the middle line no. , and that of the line nearest the tacul no. , the following are the spaces moved over by these three points in twenty-four hours: inches. distances asunder. no. . } yards. no. . } yards. no. . here we have the fact which the aspect of the glacier suggested. the first stake moves five inches a day more than the second, and the second nearly three inches a day more than the third. as surmised, therefore, the glacier is in a state of longitudinal compression, whereby a portion of it yards in length is shortened at the rate of eight inches a day. [sidenote: structure in white ice-seams.] in accordance with this result, the transverse undulations of the glacier du géant, described in the chapter upon dirt-bands, _shorten_ as they descend. a series of three of them measured along the axis of the glacier on the th of august, , gave the following respective lengths:-- links, links, links, the shortest undulation being the farthest from the origin of the undulations. this glacier then constitutes a vast ice-press, and enables us to test the explanation which refers the veined structure of the ice to pressure. the glacier itself is transversely laminated, as already stated; and in many cases a structure of extreme definition and beauty is developed in the compressed snow, which constitutes the seams of white ice. in i discovered a well-developed lenticular structure in some of these seams. in i again examined them. clearing away the superficial portions with my axe, i found, drawn through the body of the seams, long lines of blue ice of exquisite definition; in fact, i had never seen the structure so delicately exhibited. the seams, moreover, were developed in portions of the white ice which were near the _centre_ of the glacier, and where consequently filamentous sliding was entirely out of the question. [sidenote: partial summary.] partial summary. . glaciers are derived from mountain snow, which has been consolidated to ice by pressure. . that pressure is competent to convert snow into ice has been proved by experiment. . the power of yielding to pressure diminishes as the mass becomes more compact; but it does not cease even when the substance has attained the compactness which would entitle it to be called ice. . when a sufficient depth of snow collects upon the earth's surface, the lower portions are squeezed out by the pressure of the superincumbent mass. if it rests upon a slope it will yield principally in the direction of the slope, and move downwards. . in addition to this, the whole mass slides bodily along its inclined bed, and leaves the traces of its sliding on the rocks over which it passes, grinding off their asperities, and marking them with grooves and scratches in the direction of the motion. . in this way the deposit of consolidated and unconsolidated snow which covers the higher portions of lofty mountains moves slowly down into an adjacent valley, through which it descends as a true glacier, partly by sliding and partly by the yielding of the mass itself. . several valleys thus filled may unite in a single valley, the tributary glaciers welding themselves together to form a trunk-glacier. . both the main valley and its tributaries are often sinuous, and the tributaries must change their direction to form the trunk; the width of the valley often varies. the glacier is forced through narrow gorges, widening after it has passed them; the centre of the glacier moves more quickly than the sides, and the surface more quickly than the bottom; the point of swiftest motion follows the same law as that observed in the flow of rivers, shifting from one side of the centre to the other as the flexure of the valley changes. . these various effects may be reproduced by experiments on small masses of ice. the substance may moreover be moulded into vases and statuettes. straight bars of it may be bent into rings, or even coiled into knots. . ice, capable of being thus moulded, is practically incapable of being stretched. the condition essential to success is that the particles of the ice operated on shall be kept in close contact, so that when old attachments have been severed new ones may be established. . the nearer the ice is to its melting point in temperature, the more easily are the above results obtained; when ice is many degrees below its freezing point it is crushed by pressure to a white powder, and is not capable of being moulded as above. . two pieces of ice at ° fahr., with moist surfaces, when placed in contact freeze together to a rigid mass; this is called regelation. . when the attachments of pressed ice are broken, the continuity of the mass is restored by the regelation of the new contiguous surfaces. regelation also enables two tributary glaciers to weld themselves to form a continuous trunk; thus also the crevasses are mended, and the dislocations of the glacier consequent on descending cascades are repaired. this healing of ruptures extends to the smallest particles of the mass, and it enables us to account for the continued compactness of the ice during the descent of the glacier. . the quality of viscosity is practically absent in glacier-ice. where pressure comes into play the phenomena are suggestive of viscosity, but where tension comes into play the analogy with a viscous body breaks down. when subjected to strain the glacier does not yield by stretching, but by breaking; this is the origin of the crevasses. . the crevasses are produced by the mechanical strains to which the glacier is subjected. they are divided into marginal, transverse, and longitudinal crevasses; the first produced by the oblique strain consequent on the quicker motion of the centre; the second by the passage of the glacier over the summit of an incline; the third by pressure from behind and resistance in front, which causes the mass to split at right angles to the pressure [strain?]. . the moulins are formed by deep cracks intersecting glacier rivulets. the water in descending such cracks scoops out for itself a shaft, sometimes many feet wide, and some hundreds of feet deep, into which the cataract plunges with a sound like thunder. the supply of water is periodically cut off from the moulins by fresh cracks, in which new moulins are formed. . the lateral moraines are formed from the débris which loads the glacier along its edges; the medial moraines are formed on a trunk-glacier by the union of the lateral moraines of its tributaries; the terminal moraines are formed from the débris carried by the glacier to its terminus, and there deposited. the number of medial moraines on a trunk glacier is always one less than the number of tributaries. . when ordinary lake-ice is intersected by a strong sunbeam it liquefies so as to form flower-shaped figures within the mass; each flower consists of six petals with a vacuous space at the centre; the flowers are always formed parallel to the planes of freezing, and depend on the crystallization of the substance. . innumerable liquid disks, with vacuous spots, are also formed by the solar beams in glacier-ice. these empty spaces have been hitherto mistaken for air-bubbles, the flat form of the disks being erroneously regarded as the result of pressure. . these disks are indicators of the intimate constitution of glacier-ice, and they teach us that it is composed of an aggregate of parts with surfaces of crystallization in all possible planes. . there are also innumerable small cells in glacier-ice holding air and water; such cells also occur in lake-ice; and here they are due to the melting of the ice in contact with the bubble of air. experiments are needed on glacier-ice in reference to this point. . at a free surface within or without, ice melts with more ease than in the centre of a compact mass. the motion which we call heat is less controlled at a free surface, and it liberates the molecules from the solid condition sooner than when the atoms are surrounded on all sides by other atoms which impede the molecular motion. regelation is the complementary effect to the above; for here the superficial portions of a mass of ice are made virtually central by the contact of a second mass. . the dirt-bands have their origin in the ice-cascades. the glacier, in passing the brow, is transversely fractured; ridges are formed with hollows between them; these transverse hollows are the principal receptacles of the fine débris scattered over the glacier; and after the ridges have been melted away, the dirt remains in successive stripes upon the glacier. . the ice of many glaciers is laminated, and when weathered may be cloven into thin plates. in the sound ice the lamination manifests itself in blue stripes drawn through the general whitish mass of the glacier; these blue veins representing portions of ice from which the air-bubbles have been more completely expelled. this is the veined structure of the ice. it is divided into marginal, transverse, and longitudinal structure; which may be regarded as complementary to marginal, longitudinal, and transverse crevasses. the latter are produced by tension, the former by pressure, which acts in two different ways: firstly, the pressure acts upon the ice as it has acted upon rocks which exhibit the lamination technically called cleavage; secondly, it produces partial liquefaction of the ice. the liquid spaces thus formed help the escape of the air from the glacier; and the water produced, being refrozen when the pressure is relieved, helps to form the blue veins. appendix. comparative view of the cleavage of crystals and slate-rocks. a lecture delivered at the royal institution, on friday evening the th of june, .[a] when the student of physical science has to investigate the character of any natural force, his first care must be to purify it from the mixture of other forces, and thus study its simple action. if, for example, he wishes to know how a mass of water would shape itself, supposing it to be at liberty to follow the bent of its own molecular forces, he must see that these forces have free and undisturbed exercise. we might perhaps refer him to the dew-drop for a solution of the question; but here we have to do, not only with the action of the molecules of the liquid upon each other, but also with the action of gravity upon the mass, which pulls the drop downwards and elongates it. if he would examine the problem in its purity, he must do as plateau has done, withdraw the liquid mass from the action of gravity, and he would then find the shape of the mass to be perfectly spherical. natural processes come to us in a mixed manner, and to the uninstructed mind are a mass of unintelligible confusion. suppose half-a-dozen of the best musical performers to be placed in the same room, each playing his own instrument to perfection: though each individual instrument might be a well-spring of melody, still the mixture of all would produce mere noise. thus it is with the processes of nature. in nature, mechanical and molecular laws mingle, and create apparent confusion. their mixture constitutes what may be called the _noise_ of natural laws, and it is the vocation of the man of science to resolve this noise into its components, and thus to detect the "music" in which the foundations of nature are laid. the necessity of this detachment of one force from all other forces is nowhere more strikingly exhibited than in the phenomena of crystallization. i have here a solution of sulphate of soda. prolonging the mental vision beyond the boundaries of sense, we see the atoms of that liquid, like squadrons under the eye of an experienced general, arranging themselves into battalions, gathering round a central standard, and forming themselves into solid masses, which after a time assume the visible shape of the crystal which i here hold in my hand. i may, like an ignorant meddler wishing to hasten matters, introduce confusion into this order. i do so by plunging this glass rod into the vessel. the consequent action is not the pure expression of the crystalline forces; the atoms rush together with the confusion of an unorganized mob, and not with the steady accuracy of a disciplined host. here, also, in this mass of bismuth we have an example of this confused crystallization; but in the crucible behind me a slower process is going on: here there is an architect at work "who makes no chips, no din," and who is now building the particles into crystals, similar in shape and structure to those beautiful masses which we see upon the table. by permitting alum to crystallize in this slow way, we obtain these perfect octahedrons; by allowing carbonate of lime to crystallize, nature produces these beautiful rhomboids; when silica crystallizes, we have formed these hexagonal prisms capped at the ends by pyramids; by allowing saltpetre to crystallize, we have these prismatic masses; and when carbon crystallizes, we have the diamond. if we wish to obtain a perfect crystal, we must allow the molecular forces free play: if the crystallizing mass be permitted to rest upon a surface it will be flattened, and to prevent this a small crystal must be so suspended as to be surrounded on all sides by the liquid, or, if it rest upon the surface, it must be turned daily so as to present all its faces in succession to the working builder. in this way the scientific man nurses these children of his intellect, watches over them with a care worthy of imitation, keeps all influences away which might possibly invade the strict morality of crystalline laws, and finally sees them developed into forms of symmetry and beauty which richly reward the care bestowed upon them. in building up crystals, these little atomic bricks often arrange themselves into layers which are perfectly parallel to each other, and which can be separated by mechanical means; this is called the cleavage of the crystal. i have here a crystallized mass which has thus far escaped the abrading and disintegrating forces which, sooner or later, determine the fate of sugar-candy. if i am skilful enough, i shall discover that this crystal of sugar cleaves with peculiar facility in one direction. here, again, i have a mass of rock-salt: i lay my knife upon it, and with a blow cleave it in this direction; but i find on further examining this substance that it cleaves in more directions than one. laying my knife at right angles to its former position, the crystal cleaves again; and, finally placing the knife at right angles to the two former positions, the mass cleaves again. thus rock-salt cleaves in three directions, and the resulting solid is this perfect cube, which may be broken up into any number of smaller cubes. here is a mass of iceland spar, which also cleaves in three directions, not at right angles, but obliquely to each other, the resulting solid being a rhomboid. in each of these cases the mass cleaves with equal facility in all three directions. for the sake of completeness, i may say that many substances cleave with unequal facility in different directions, and the heavy spar i hold in my hand presents an example of this kind of cleavage. turn we now to the consideration of some other phenomena to which the term cleavage may be applied. this piece of beech-wood cleaves with facility parallel to the fibre, and if our experiments were fine enough we should discover that the cleavage is most perfect when the edge of the axe is laid across the rings which mark the growth of the tree. the fibres of the wood lie side by side, and a comparatively small force is sufficient to separate them. if you look at this mass of hay severed from a rick, you will see a sort of cleavage developed in it also; the stalks lie in parallel planes, and only a small force is required to separate them laterally. but we cannot regard the cleavage of the tree as the same in character as the cleavage of the hayrick. in the one case it is the atoms arranging themselves according to organic laws which produce a cleavable structure; in the other case the easy separation in a certain direction is due to the mechanical arrangement of the coarse sensible masses of stalks of hay. in like manner i find that this piece of sandstone cleaves parallel to the planes of bedding. this rock was once a powder, more or less coarse, held in mechanical suspension by water. the powder was composed of two distinct parts, fine grains of sand and small plates of mica. imagine a wide strand covered by a tide which holds such powder in suspension:[b] how will it sink? the rounded grains of sand will reach the bottom first, the mica afterwards, and when the tide recedes we have the little plates shining like spangles upon the surface of the sand. each successive tide brings its charge of mixed powder, deposits its duplex layer day after day, and finally masses of immense thickness are thus piled up, which, by preserving the alternations of sand and mica, tell the tale of their formation. i do not wish you to accept this without proof. take the sand and mica, mix them together in water, and allow them to subside, they will arrange themselves in the manner i have indicated; and by repeating the process you can actually build up a sandstone mass which shall be the exact counterpart of that presented by nature, as i have done in this glass jar. now this structure cleaves with readiness along the planes in which the particles of mica are strewn. here is a mass of such a rock sent to me from halifax: here are other masses from the quarries of over darwen in lancashire. with a hammer and chisel you see i can cleave them into flags; indeed these flags are made use of for roofing purposes in the districts from which the specimens have come, and receive the name of "slate-stone." but you will discern, without a word from me, that this cleavage is not a crystalline cleavage any more than that of a hayrick is. it is not an arrangement produced by molecular forces; indeed it would be just as reasonable to suppose that in this jar of sand and mica the particles arranged themselves into layers by the forces of crystallization, instead of by the simple force of gravity, as to imagine that such a cleavage as this could be the product of crystallization. this, so far as i am aware of, has never been imagined, and it has been agreed among geologists not to call such splitting as this cleavage at all, but to restrict the term to a class of phenomena which i shall now proceed to consider. those who have visited the slate quarries of cumberland and north wales will have witnessed the phenomena to which i refer. we have long drawn our supply of roofing-slates from such quarries; schoolboys ciphered on these slates, they were used for tombstones in churchyards, and for billiard-tables in the metropolis; but not until a comparatively late period did men begin to inquire how their wonderful structure was produced. what is the agency which enables us to split honister crag, or the cliffs of snowdon, into laminæ from crown to base? this question is at the present moment one of the greatest difficulties of geologists, and occupies their attention perhaps more than any other. you may wonder at this. looking into the quarry of penrhyn, you may be disposed to explain the question as i heard it explained two years ago. "these planes of cleavage," said a friend who stood beside me on the quarry's edge, "are the planes of stratification which have been lifted by some convulsion into an almost vertical position." but this was a great mistake, and indeed here lies the grand difficulty of the problem. these planes of cleavage stand in most cases at a high angle to the bedding. thanks to sir roderick murchison, who has kindly permitted me the use of specimens from the museum of practical geology (and here i may be permitted to express my acknowledgments to the distinguished staff of that noble establishment, who, instead of considering me an intruder, have welcomed me as a brother), i am able to place the proof of this before you. here is a mass of slate in which the planes of bedding are distinctly marked; here are the planes of cleavage, and you see that one of them makes a large angle with the other. the cleavage of slates is therefore not a question of stratification, and the problem which we have now to consider is, "by what cause has this cleavage been produced?" in an able and elaborate essay on this subject in , professor sedgwick proposed the theory that cleavage is produced by the action of crystalline or polar forces after the mass has been consolidated. "we may affirm," he says, "that no retreat of the parts, no contraction of dimensions in passing to a solid state can explain such phenomena. they appear to me only resolvable on the supposition that crystalline or polar forces acted upon the whole mass simultaneously in one direction and with adequate force." and again, in another place: "crystalline forces have rearranged whole mountain-masses, producing a beautiful crystalline cleavage, passing alike through all the strata."[c] the utterance of such a man struck deep, as was natural, into the minds of geologists, and at the present day there are few who do not entertain this view either in whole or in part.[d] the magnificence of the theory, indeed, has in some cases caused speculation to run riot, and we have books published, aye and largely sold, on the action of polar forces and geologic magnetism, which rather astonish those who know something about the subject. according to the theory referred to, miles and miles of the districts of north wales and cumberland, comprising huge mountain-masses, are neither more nor less than the parts of a gigantic crystal. these masses of slate were originally fine mud; this mud is composed of the broken and abraded particles of older rocks. it contains silica, alumina, iron, potash, soda, and mica, mixed in sensible masses mechanically together. in the course of ages the mass became consolidated, and the theory before us assumes that afterwards a process of crystallization rearranged the particles and developed in the mass a single plane of crystalline cleavage. with reference to this hypothesis, i will only say that it is a bold stretch of analogies; but still it has done good service: it has drawn attention to the question; right or wrong, a theory thus thoughtfully uttered has its value; it is a dynamic power which operates against intellectual stagnation; and, even by provoking opposition, is eventually of service to the cause of truth. it would, however, have been remarkable, if, among the ranks of geologists themselves, men were not found to seek an explanation of the phenomena in question, which involved a less hardy spring on the part of the speculative faculty than the view to which i have just referred. the first step in an inquiry of this kind is to put oneself into contact with nature, to seek facts. this has been done, and the labours of sharpe (the late president of the geological society, who, to the loss of science and the sorrow of all who knew him, has so suddenly been taken away from us), sorby, and others, have furnished us with a body of evidence which reveals to us certain important physical phenomena, associated with the appearance of slaty cleavage, if they have not produced it. the nature of this evidence we will now proceed to consider. fossil shells are found in these slate-rocks. i have here several specimens of such shells, occupying various positions with regard to the cleavage planes. they are squeezed, distorted, and crushed. in some cases a flattening of the convex shell occurs, in others the valves are pressed by a force which acted in the plane of their junction, but in all cases the distortion is such as leads to the inference that the rock which contains these shells has been subjected to enormous pressure in a direction at right angles to the planes of cleavage; the shells are all flattened and spread out upon these planes. i hold in my hand a fossil trilobite of normal proportions. here is a series of fossils of the same creature which have suffered distortion. some have lain across, some along, and some oblique to the cleavage of the slate in which they are found; in all cases the nature of the distortion is such as required for its production a compressing force acting at right angles to the planes of cleavage. as the creatures lay in the mud in the manner indicated, the jaws of a gigantic vice appear to have closed upon them and squeezed them into the shape you see. as further evidence of the exertion of pressure, let me introduce to your notice a case of contortion which has been adduced by mr. sorby. the bedding of the rock shown in this figure[e] was once horizontal; at a we have a deep layer of mud, and at _m n_ a layer of comparatively unyielding gritty material; below that again, at b, we have another layer of the fine mud of which slates are formed. this mass cleaves along the shading lines of the diagram; but look at the shape of the intermediate bed: it is contorted into a serpentine form, and leads irresistibly to the conclusion that the mass has been pressed together at right angles to the planes of cleavage. this action can be experimentally imitated, and i have here a piece of clay in which this is done and the same result produced on a small scale. the amount of compression, indeed, might be roughly estimated by supposing this contorted bed _m n_ to be stretched out, its length measured and compared with the distance _c d_; we find in this way that the yielding of the mass has been considerable. let me now direct your attention to another proof of pressure. you see the varying colours which indicate the bedding on this mass of slate. the dark portion, as i have stated, is gritty, and composed of comparatively coarse particles, which, owing to their size, shape, and gravity, sink first and constitute the bottom of each layer. gradually from bottom to top the coarseness diminishes, and near the upper surface of each layer we have a mass of comparatively fine clean mud. sometimes this fine mud forms distinct layers in a mass of slate-rock, and it is the mud thus consolidated from which are derived the german razor-stones, so much prized for the sharpening of surgical instruments. i have here an example of such a stone. when a bed is thin, the clean white mud is permitted to rest, as in this case, upon a slab of the coarser slate in contact with it: when the bed is thick, it is cut into slices which are cemented to pieces of ordinary slate, and thus rendered stronger. the mud thus deposited sometimes in layers is, as might be expected, often rolled up into nodular masses, carried forward, and deposited by the rivers from which the slate-mud has subsided. here, indeed, are such nodules enclosed in sandstone. everybody who has ciphered upon a school-slate must remember the whitish-green spots which sometimes dotted the surface of the slate; he will remember how his slate-pencil usually slid over such spots as if they were greasy. now these spots are composed of the finer mud, and they could not, on account of their fineness, _bite_ the pencil like the surrounding gritty portions of the slate. here is a beautiful example of the spots: you observe them on the cleavage surface in broad patches; but if this mass has been compressed at right angles to the planes of cleavage, ought we to expect the same marks when we look at the edge of the slab? the nodules will be flattened by such pressure, and we ought to see evidence of this flattening when we turn the slate edgeways. here it is. the section of a nodule is a sharp ellipse with its major axis parallel to the cleavage. there are other examples of the same nature on the table; i have made excursions to the quarries of wales and cumberland, and to many of the slate-yards of london, but the same fact invariably appears, and thus we elevate a common experience of our boyhood into evidence of the highest significance as regards one of the most important problems of geology. in examining the magnetism of these slates, i was led to infer that these spots would contain a less amount of iron than the surrounding dark slate. the analysis was made for me by mr. hambly in the laboratory of dr. percy at the school of mines. the result which is stated in this table justifies the conclusion to which i have referred. _analysis of slate._ purple slate. two analyses. . percentage of iron . . " " . mean . greenish slate. . percentage of iron . . " " . mean . the quantity of iron in the dark slate immediately adjacent to the greenish spot is, according to these analyses, nearly double of the quantity contained in the spot itself. this is about the proportion which the magnetic experiments suggested. let me now remind you that the facts which i have brought before you are typical facts--each is the representative of a class. we have seen shells crushed, the unhappy trilobites squeezed, beds contorted, nodules of greenish marl flattened; and all these sources of independent testimony point to one and the same conclusion, namely, that slate-rocks have been subjected to enormous pressure in a direction at right angles to the planes of cleavage.[f] in reference to mr. sorby's contorted bed, i have said that by supposing it to be stretched out and its length measured, it would give us an idea of the amount of yielding of the mass above and below the bed. such a measurement, however, would not quite give the amount of yielding; and here i would beg your attention to a point, the significance of which has, so far as i am aware of, hitherto escaped attention. i hold in my hand a specimen of slate, with its bedding marked upon it; the lower portions of each bed are composed of a comparatively coarse gritty material, something like what you may suppose this contorted bed to be composed of. well, i find that the cleavage takes a bend in crossing these gritty portions, and that the tendency of these portions is to cleave more at right angles to the bedding. look to this diagram: when the forces commenced to act, this intermediate bed, which though comparatively unyielding is not entirely so, suffered longitudinal pressure; as it bent, the pressure became gradually more lateral, and the direction of its cleavage is exactly such as you would infer from a force of this kind--it is neither quite across the bed, nor yet in the same direction as the cleavage of the slate above and below it, but intermediate between the two. supposing the cleavage to be at right angles to the pressure, this is the direction which it ought to take across these more unyielding strata. thus we have established the concurrence of the phenomena of cleavage and pressure--that they accompany each other; but the question still remains, is this pressure of itself sufficient to account for the cleavage? a single geologist, as far as i am aware, answers boldly in the affirmative. this geologist is sorby, who has attacked the question in the true spirit of a physical investigator. you remember the cleavage of the flags of halifax and over darwen, which is caused by the interposition of plates of mica between the layers. mr. sorby examines the structure of slate-rock, and finds plates of mica to be a constituent. he asks himself, what will be the effect of pressure upon a mass containing such plates confusedly mixed up in it? it will be, he argues--and he argues rightly--to place the plates with their flat surfaces more or less perpendicular to the direction in which the pressure is exerted. he takes scales of the oxide of iron, mixes them with a fine powder, and, on squeezing the mass, finds that the tendency of the scales is to set themselves at right angles to the line of pressure. now the planes in which these plates arrange themselves will, he contends, be those along which the mass cleaves. i could show you, by tests of a totally different character from those applied by mr. sorby, how true his conclusion is, that the effect of pressure on elongated particles or plates will be such as he describes it. nevertheless, while knowing this fact, and admiring the ability with which mr. sorby has treated this question, i cannot accept his explanation of slate-cleavage. i believe that even if these plates of mica were wholly absent, the cleavage of slate-rocks would be much the same as it is at present. i will not dwell here upon minor facts,--i will not urge that the perfection of the cleavage bears no relation to the quantity of mica present; but i will come at once to a case which to my mind completely upsets the notion that such plates are a necessary element in the production of cleavage. here is a mass of pure white wax: there are no mica particles here; there are no scales of iron, or anything analogous mixed up with the mass. here is the self-same substance submitted to pressure. i would invite the attention of the eminent geologists whom i see before me to the structure of this mass. no slate ever exhibited so clean a cleavage; it splits into laminæ of surpassing tenuity, and proves at a single stroke that pressure is sufficient to produce cleavage, and that this cleavage is independent of the intermixed plates of mica assumed in mr. sorby's theory. i have purposely mixed this wax with elongated particles, and am unable to say at the present moment that the cleavage is sensibly affected by their presence,--if anything, i should say they rather impair its fineness and clearness than promote it. the finer the slate the more perfect will be the resemblance of its cleavage to that of the wax. compare the surface of the wax with the surface of this slate from borrodale in cumberland. you have precisely the same features in both: you see flakes clinging to the surfaces of each, which have been partially torn away by the cleavage of the mass: i entertain the conviction that if any close observer compares these two effects, he will be led to the conclusion that they are the product of a common cause.[g] but you will ask, how, according to my view, does pressure produce this remarkable result? this may be stated in a very few words. nature is everywhere imperfect! the eye is not perfectly achromatic, the colours of the rose and tulip are not pure colours, and the freshest air of our hills has a bit of poison in it. in like manner there is no such thing in nature as a body of perfectly homogeneous structure. i break this clay which seems so intimately mixed, and find that the fracture presents to my eyes innumerable surfaces along which it has given way, and it has yielded along these surfaces because in them the cohesion of the mass is less than elsewhere. i break this marble, and even this wax, and observe the same result: look at the mud at the bottom of a dried pond; look to some of the ungravelled walks in kensington gardens on drying after rain,--they are cracked and split, and other circumstances being equal, they crack and split where the cohesion of the mass is least. take then a mass of partially consolidated mud. assuredly such a mass is divided and subdivided by surfaces along which the cohesion is comparatively small. penetrate the mass, and you will see it composed of numberless irregular nodules bounded by surfaces of weak cohesion. figure to your mind's eye such a mass subjected to pressure,--the mass yields and spreads out in the direction of least resistance;[h] the little nodules become converted into laminæ, separated from each other by surfaces of weak cohesion, and the infallible result will be that such a mass will cleave at right angles to the line in which the pressure is exerted. further, a mass of dried mud is full of cavities and fissures. if you break dried pipe-clay you see them in great numbers, and there are multitudes of them so small that you cannot see them. i have here a piece of glass in which a bubble was enclosed; by the compression of the glass the bubble is flattened, and the sides of the bubble approach each other so closely as to exhibit the colours of thin plates. a similar flattening of the cavities must take place in squeezed mud, and this must materially facilitate the cleavage of the mass in the direction already indicated. although the time at my disposal has not permitted me to develop this thought as far as i could wish, yet for the last twelve months the subject has presented itself to me almost daily under one aspect or another. i have never eaten a biscuit during this period in which an intellectual joy has not been superadded to the more sensual pleasure, for i have remarked in all such cases cleavage developed in the mass by the rolling-pin of the pastrycook or confectioner. i have only to break these cakes, and to look at the fracture, to see the laminated structure of the mass; nay, i have the means of pushing the analogy further: i have here some slate which was subjected to a high temperature during the conflagration of mr. scott russell's premises. i invite you to compare this structure with that of a biscuit; air or vapour within the mass has caused it to swell, and the mechanical structure it reveals is precisely that of a biscuit. i have gone a little into the mysteries of baking while conducting my inquiries on this subject, and have received much instruction from a lady-friend in the manufacture of puff-paste. here is some paste baked in this house under my own superintendence. the cleavage of our hills is accidental cleavage, but this is cleavage with intention. the volition of the pastrycook has entered into the formation of the mass, and it has been his aim to preserve a series of surfaces of structural weakness, along which the dough divides into layers. puff-paste must not be handled too much, for then the continuity of the surfaces is broken; it ought to be rolled on a cold slab, to prevent the butter from melting and diffusing itself through the mass, thus rendering it more homogeneous and less liable to split. this is the whole philosophy of puff-paste; it is a grossly exaggerated case of slaty cleavage. as time passed on, cases multiplied, illustrating the influence of pressure in producing lamination. mr. warren de la rue informs me that he once wished to obtain white-lead in a fine granular state, and to accomplish this he first compressed the mass: the mould was conical, and permitted the mass to spread a little laterally under the pressure. the lamination was as perfect as that of slate, and quite defeated him in his effort to obtain a granular powder. mr. brodie, as you are aware, has recently discovered a new kind of graphite: here is the substance in powder, of exquisite fineness. this powder has the peculiarity of clinging together in little confederacies; it cannot be shaken asunder like lycopodium; and when the mass is squeezed, these groups of particles flatten, and a perfect cleavage is produced. mr. brodie himself has been kind enough to furnish me with specimens for this evening's lecture. i will cleave them before you: you see they split up into plates which are perpendicular to the line in which the pressure was exerted. this testimony is all the more valuable, as the facts were obtained without any reference whatever to the question of cleavage. i have here a mass of that singular substance boghead cannel. this was once a mass of mud, more or less resembling this one, which i have obtained from a bog in lancashire. i feel some hesitation in bringing this substance before you, for, as in other cases, so in regard to boghead cannel, science--not science, let me not libel it, but the quibbling, litigious, money-loving portion of human nature speaking through the mask of science--has so contrived to split hairs as to render the qualities of the substance somewhat mythical. i shall therefore content myself with showing you how it cleaves, and with expressing my conviction that pressure had a great share in the production of this cleavage. the principle which i have enunciated is so simple as to be almost trivial; nevertheless, it embraces not only the cases i have mentioned, but, if time permitted, i think i could show you that it takes a much wider range. when iron is taken from the puddling furnace, it is a more or less spongy mass: it is at a welding heat, and at this temperature is submitted to the process of rolling: bright smooth bars such as this are the result of this rolling. but i have said that the mass is more or less spongy or nodular, and, notwithstanding the high heat, these nodules do not perfectly incorporate with their neighbours: what then? you would say that the process of rolling must draw the nodules into fibres--it does so; and here is a mass acted upon by dilute sulphuric acid, which exhibits in a striking manner this fibrous structure. the experiment was made by my friend dr. percy, without any reference to the question of cleavage. here are other cases of fibrous iron. this fibrous structure is the result of mechanical treatment. break a mass of ordinary iron and you have a granular fracture; beat the mass, you elongate these granules, and finally render the mass fibrous. here are pieces of rails along which the wheels of locomotives have slidden; the granules have yielded and become plates; they exfoliate or come off in leaves. all these effects belong, i believe, to the great class of phenomena of which slaty cleavage forms the most prominent example.[i] thus, ladies and gentlemen, we have reached the termination of our task. i commenced by exhibiting to you some of the phenomena of crystallization. i have placed before you the facts which are found to be associated with the cleavage of slate-rocks. these facts, as finely expressed by helmholtz, are so many telescopes to our spiritual vision, by which we can see backward through the night of antiquity, and discern the forces which have been in operation upon the earth's surface "ere the lion roared, or the eagle soared." from evidence of the most independent and trustworthy character, we come to the conclusion that these slaty masses have been subjected to enormous pressure, and by the sure method of experiment we have shown--and this is the only really new point which has been brought before you--how the pressure is sufficient to produce the cleavage. expanding our field of view, we find the self-same law, whose footsteps we trace amid the crags of wales and cumberland, stretching its ubiquitous fingers into the domain of the pastrycook and ironfounder; nay, a wheel cannot roll over the half-dried mud of our streets without revealing to us more or less of the features of this law. i would say, in conclusion, that the spirit in which this problem has been attacked by geologists indicates the dawning of a new day for their science. the great intellects who have laboured at geology, and who have raised it to its present pitch of grandeur, were compelled to deal with the subject in mass; they had no time to look after details. but the desire for more exact knowledge is increasing; facts are flowing in, which, while they leave untouched the intrinsic wonders of geology, are gradually supplanting by solid truths the uncertain speculations which beset the subject in its infancy. geologists now aim to imitate, as far as possible, the conditions of nature, and to produce her results; they are approaching more and more to the domain of physics; and i trust the day will soon come when we shall interlace our friendly arms across the common boundary of our sciences, and pursue our respective tasks in a spirit of mutual helpfulness, encouragement, and good-will. footnotes: [a] referred to in the introduction. [b] i merely use this as an illustration; the deposition may have really been due to sediment carried down by rivers. but the action must have been periodic, and the powder duplex. [c] 'transactions of the geological society,' ser. ii. vol. iii. p. . [d] in a letter to sir charles lyell, dated from the cape of good hope, february , , sir john herschel writes as follows:--"if rocks have been so heated as to allow of a commencement of crystallization, that is to say, if they have been heated to a point at which the particles can begin to move amongst themselves, or at least on their own axes, some general law must then determine the position in which these particles will rest on cooling. probably that position will have some relation to the direction in which the heat escapes. now when all or a majority of particles of the same nature have a general tendency to one position, that must of course determine a cleavage plane." [e] omitted here. [f] while to my mind the evidence in proof of pressure seems perfectly irresistible, i by no means assert that the manner in which i stated it is incapable of modification. all that i deem important is the fact that pressure has been exerted; and provided this remain firm, the fate of any minor portion of the evidence by which it is here established is of comparatively little moment. [g] i have usually softened the wax by warming it, kneaded it with the fingers, and pressed it between thick plates of glass previously wetted. at the ordinary summer-temperature the wax is soft, and tears rather than cleaves; on this account i cool my compressed specimens in a mixture of pounded ice and salt, and when thus cooled they split beautifully. [h] it is scarcely necessary to say that if the mass were squeezed equally in _all_ directions no laminated structure could be produced; it must have room to yield in a lateral direction. [i] an eminent authority informs me that he believes these surfaces of weak cohesion to be due to the interposition of films of graphite, and not to any tendency of the iron itself to become fibrous: this of course does not in any way militate against the theory which i have ventured to propose. all that the theory requires is surfaces of weak cohesion, however produced, and a change of shape of such surfaces consequent on pressure or rolling. index. Æggischhorn, , . agassiz on glacier motion, , . air-bubbles, , . aletsch glacier, . -- --, bedding and structure observed on, , . aletschhorn, cloud iridescences on, , . allalein glacier, . alpine climbers, suggestions to, . alps, winter temperature of, . altmann's theory of glacier motion, . ancient glaciers, action of, , . arveiron, arch of, , . atmosphere, permeability of, to radiant heat, , - . atmospheric refraction, . avalanche at saas, . --, sound of, explained, , . bakewell, mr., on motion of glacier des bossons, . balmat, auguste, , . bedding, lines of, . bennen, johann joseph, , . bergschrund, , . "blower," glacier, . blue colour of ice, . -- -- -- snow, , , , . -- -- -- water, , , - . blueness of sky, , , - . blue veins, , . boiling-point, influence of pressure on, . -- -- at different altitudes, , , , , , , . bois, glacier des, , , . brévent, ascent of, . brocken, spirit of the, , . bubbles, in ice, , , , . -- in snow, , . capillaries of glacier, - . cave of ice, . cavities in ice, , , . cells in ice, , see bubbles. chamouni, . --, difficulties at, , . -- in winter, , . charmoz, view from, , , . charpentier's theory of glacier motion, . chemical action, rays producing, . chromatic effects, . cleavage, . -- and stratification distinct, , , . -- caused by pressure, , . --, contortions of, , . -- of crystals and slate rocks, lecture on, . -- of glaciers, , , - . -- -- ice, , . -- -- slate, &c., , . "cleft station," the, , . clouds, formation and dissipation of, , , , . --, iridescent, , , , , . -- on mont blanc, . -- on monte rosa, . --, winter, at montanvert, . colour answers to pitch, . colours of sky, . --, subjective, . comet, discovery of, . compass affected by rocks, . crepitation of glaciers, , . crevasses, (_marginal_, ; _transverse_, ; _longitudinal_, ), . --, first opening of, , . crumples in ice, , , . crystallization of ice, . crystals, cleavage of, , . -- of snow, , , . deafness, artificial, . differential motion, . -- --, dr. whewell on, . diffraction, explanation of, . dirt-bands, , , , , , . -- --, maps of, , , . -- --, forbes on, . -- --, source of, , . disks in ice, planes of, , , . dollfuss, m., hut of, , . dôme du goûter, , . donny, m., on cohesion of liquids, . echoes, theory of, . eismeer, the, , . expedition of , oberland and tyrol, - . -- -- , montanvert and mer de glace, - . -- -- , oberland, valais, and monte rosa district, - . -- -- , winter, chamouni, and mer de glace, - . faraday, prof., on regelation, . faulberg, cave of, . fée, glacier of, . fend, . finsteraarhorn, , . --, summit of, . flowers, liquid, in ice, , - , . forbes, prof., comparison of glacier to river, , . -- --, on glacier motion, , , . -- --, on magnetism of rocks, . -- --, on veined structure, . -- --, viscous theory, , , , . freezing, planes of, , , . frost-bites, . frozen flowers, , . furgge glacier, structure crossing strata on, , - . gases, passage of heat through, . géant, col du, , . géant, glacier du, - , , - . --, measurements on, - . --, motion of, , . --, white ice seams of, , . gebatsch alp, . --, glacier of, , . geneva, lake of, , - . glaciers, ancient, action of, , . -- "blower," . --, capillaries of, - . --, crepitation of, , . -- d'écoulement, . -- de léchaud, see léchaud. -- des bois, , , . -- du géant, see géant. -- du talèfre, see talèfre. --, groovings on, , , . --, measurement of, . -- motion, , - , . -- --, earlier theories of, - . -- --, pressure theory of, . --, origin of, - . -- réservoirs, . --, ridges on, , . --, structure of, , , see veined structure. -- tables, , . --, veins of, , , . --, wrinkles on, . goethe's theory of colours, . görner glacier, , . görner grat, , . görnerhorn glacier, , . grand plateau, . grands mulets, , . graun, . grimsel, the, , . grindelwald, lower glacier of, , , , . groovings on glaciers, , , . grüner's theory of glacier motion, . guides of chamouni, rules of, , , . -- lost in crevasse, . guyot, m., on veined structure, . hailstones, conical, . --, spherical, . handeck, waterfall of, . hasli, valley of, , . heat and light, , , . -- -- work, . --, luminous, - . --, mechanical equivalent of, . --, obscure, . --, passage through gases, - . --, radiant, . -- --, permeability of atmosphere to, , - . --, radiated, . --, specific, . heisse platte, the, . hirst, mr., measurements on mer de glace, , , , , , , . hochjoch, . höchste spitze of monte rosa, . hopkins, mr., on crevasses, , . hôtel des neufchâtelois, , , . hugi on glacier motion, . huxley, mr., on glacier capillaries, . -- --, on water-cells, , . hydrogen, effect on rays, . ice, blue colour of, . -- cascades, , , . -- cave, . -- cells, , see bubbles. -- cones, . --, cracking of, , . --, crystallization of, . --, effects of pressure on, , . --, experiments on, . --, friability of, . --, liquefaction of, , . --, liquid flowers in, - , . --, thomson's theory of plasticity of, . --, softening of, . --, structure of, , . --, temperature of, , . --, white, seams of, , , . illumination of trees, &c., at sunrise and sunset, , . interference rings, . -- spectra, , , , . iridescent clouds, , , , , . jardin, the, , . joch, the passage of a, . joule, m., on heat and work, . jungfrau, the, . --, evening near, . laminated structure, , , . léchaud, glacier de, , . -- -- --, motion of, , - . lenticular structure, . light and heat, , , . --, undulation theory of, . linth, m. escher de la, . liquefaction of ice, , . liquid flowers, , - , . magnetic force, . magnetism of rocks, , , . märjelen see, , . mastic, brücke's solution of, . mattmark see, . maximum motion, locus of point of, , . mayenwand, summit of, , , . mayer, on connexion of heat with work, . measurement of glaciers, . mer de glace, - , - , . -- -- --, dirt-bands of the, (seen from charmoz, , ; from cleft station, , ; from the flégère, ). -- -- --, map of, , . -- -- --, motion of, - . -- -- --, winter motion of, , . -- -- --, winter visit to, , - . milk, cause of blueness of, . mirage, . montanvert, , , . -- in winter, . mont blanc, first ascent of, . -- --, second ascent of, . -- --, summit of, , . monte rosa, first ascent of, . -- --, second ascent of, . -- --, summit of, , . -- --, western glacier of, , . -- --, zones of colour, , . moraines, . -- of talèfre, , , , . motion of glaciers, , - , . moulins, , . --, depth of, . --, motion of, . necker, letter from, . neufchâtelois, hôtel des, , , . névé ice, , . oberland, the, visited, - ; - ; . oils, effect of films of, . person, m., on softening of ice, . pistol fired on summit of mont blanc, , , . pitch of musical sounds, . planes of freezing, , , . plasticity of ice, thomson's theory of, . polar forces, . pressure and cleavage, see cleavage. -- and liquefaction of ice, , . -- -- veined structure, ; - , - , , - . --, effects of, on boiling point, . -- -- -- -- ice, , . -- theory of glacier motion, . radiant heat, , . rays, calorific, . --, transmission of, . redness of sunset, . refraction on lake of geneva, . regelation, , . reichenbach fall, . rendu, comparison of glacier to river, . --, measurements of glaciers, . --, notice of regelation, . -- on conversion of snow into ice, . -- on ductility, . -- on law of circulation, . -- on motion of glaciers, . -- on veined structure, . -- theory of glaciers, . rhone at lake of geneva, , . -- glacier, , , , . -- --, chromatic effects, , . ridges on glaciers, , . riffelhorn, the, , - . rings, interference, . -- round sun, , . ripples deduced from rings, . ripple theory, forbes on, . -- -- of veined structure, . -- waves, movement of, . river and glacier, analogies between, - , ; . rocks, magnetism of, , , . saas, avalanche at, . sabine, gen., on veined structure, . sand-cones, . saussure's theory of glacier motion, , . scheuchzer's theory of glacier motion, . seams, white, in ice, , , , . sedgwick, prof., on cleavage, - , , . séracs, , . serpentine, boulders of, . shadows, coloured, . sharpe, on slaty cleavage, , . silberhorn, the, . sky, blueness of, , , . --, colours of, explained, . slate, cleavage of, , . snow, blue colour of, , , . -- crystals, , , . --, dry, . -- line, , . --, perpetual, . --, sound of breaking, . -- storm, sound through, . --, whiteness of, explained, . sorby, mr., on slaty cleavage, , . sound in a vacuum, . --, intensity of, . --, rate of motion of, . spectra, interference, , , , . spectrum, rays of, . stars, twinkling of, , . stelvio, pass of, . storm on grands mulets, . -- -- mer de glace, . strahleck, glacier of, , . --, passage of, , . strata of ice, . stratification of névé, . -- -- slate, , . structure, doubts regarding, , , . -- of ice, , , see veined structure. subjective colours, . summary of glacier theory, . sun, rings round, , . sunrise at chamouni, . -- and sunset, illumination of trees, &c., at, , . sunset, gorgeous, . tables, glacier, , - . tacul, motion of ice-wall at, . talèfre, glacier of, , - , . --, moraines of, , , , . temperature, winter, of alps, . theodolite, use of, . theory of cleavage, . thermometer at jardin, . -- buried on mont blanc, . -- on finsteraarhorn, . thomson, prof., theory of plasticity, . -- -- -- -- regelation, . twinkling of stars, , . tyrol, the, . undulation theory of light, . unteraar, glacier of, , , . vacuum in ice-cavities, , . veined structure, (_marginal_, ; _transverse_, ; _longitudinal_, ), , , . -- --, experiments on, , . -- -- caused by pressure, - , - , , - . -- -- crossing strata, - . -- --, forbes on, . -- --, gen. sabine on, . -- --, m. guyot on, . -- --, ripple theory of, . viesch, glacier of, , . viscosity, , , , , . water absorbs red rays, . --, blue colour of, ; , , . --, rippling waves of, . waves, frozen, , . --, interference of, . -- motion, weber on, , . -- of sound, . wengern alp, . wetterhorn, echoes of, . white ice, seams of, , , , , . whiteness of ice, , , . winter motion of mer de glace, . wrinkles on glacier, . young, thomas, theory of light, . _spottiswoode & co. printers, new-street square, london._ works by john tyndall. fragments of science: a series of detached essays, addresses, and reviews. vols. crown vo. _s._ vol. i.--the constitution of nature--radiation--on radiant heat in relation to the colour and chemical constitution of bodies--new chemical reactions produced by light--on dust and disease--voyage to algeria to observe the eclipse--niagara--the parallel roads of glen roy--alpine sculpture--recent experiments on fog-signals--on the study of physics--on crystalline and slaty cleavage--on paramagnetic and diamagnetic forces--physical basis of solar chemistry--elementary magnetism--on force--contributions to molecular physics--life and letters of faraday--the copley medalist of --the copley medalist of --death by lightning--science and the spirits. vol. ii.--reflections on prayer and natural law--miracles and special providences--on prayer as a form of physical energy--vitality--matter and force--scientific materialism--an address to students--scientific use of the imagination--the belfast address--apology for the belfast address--the rev. james martineau and the belfast address--fermentation, and its bearings on surgery and medicine--spontaneous generation--science and man--professor virchow and evolution--the electric light. new fragments. crown vo. _s._ _d._ contents: the sabbath--goethe's 'farbenlehre'--atoms, molecules and ether waves--count rumford--louis pasteur, his life and labours--the rainbow and its congeners--address delivered at the birkbeck institution on october , --thomas young--life in the alps--about common water--personal recollections of thomas carlyle--on unveiling the statue of thomas carlyle--on the origin, propagation, and prevention of phthisis--old alpine jottings--a morning on alp lusgen. lectures on sound. with frontispiece of fog-syren, and other woodcuts and diagrams in the text. crown vo. _s._ _d._ heat, a mode of motion. with woodcuts and diagrams. crown vo. _s._ lectures on light delivered in the united states in and . with portrait, lithographic plate, and diagrams. crown vo. _s._ essays on the floating matter of the air in relation to putrefaction and infection. with woodcuts. crown vo. _s._ _d._ researches on diamagnetism and magne-crystallic action; including the question of diamagnetic polarity. crown vo. _s._ notes of a course of nine lectures on light, delivered at the royal institution of great britain, . crown vo. _s._ _d._ notes of a course of seven lectures on electrical phenomena and theories, delivered at the royal institution of great britain, . crown vo. _s._ _d._ lessons in electricity at the royal institution, - . with woodcuts and diagrams. crown vo. _s._ _d._ faraday as a discoverer. crown vo. _s._ _d._ london: longmans, green, & co. transcriber's notes. the titles from the list of illustrations were copied to the captions of the figures that otherwise had no caption, for the convenience of the reader. the "sidenotes" in the main body of the text were originally page headers. they have been moved to a place more fitting for the flow, typically to the head of the appropriate paragraph. spelling variants where there was no obviously preferred choice were retained. these include: "cleft-station" and "cleft station," plus variants; "cima di jazzi" and "cima de jazzi;" "fanlike" and "fan-like;" "firewood" and "fire-wood;" "flégère" and "flegère;" "foreshorten(ed)" and "fore-shorten(ing);" "generalisation" and "generalization;" "judgment" and "judgement;" "kumm" and "kumme," which may be the same as "kamm;" "lime light" and "lime-light;" "realize" and "realise(d);" "recognise" and "recognize(d);" "rearranged" and "re-arranged;" "refrozen" and "re-frozen;" "self-same" and "selfsame;" "semifluid" and "semi-fluid;" "sundial" and "sun-dial;" "trift" and "trifti," probably the same glacier; "weatherworn" and "weather-worn." in the latin- encoded text version, the oe-ligature was replaced by the two separate characters, "oe." changed "hockjoch" to "hochjoch" on page xi: "passage of the hochjoch." changed " " to " " on page xvii, as the page number for chapter . changed "icefall" to "ice-fall" on page xxvi: "part of ice-fall." changed "havresack" to "haversack" on page : "my waterproof haversack." changed "afflùent" to "affluent" on page : "finsteraar affluent." changed " °. " to " . °" on page . changed "gulleys" to "gullies" on page : "fissures and gullies." changed "snowstorm" to "snow-storm" in the sidenote from page : "sound through the snow-storm." changed "neutralise" to "neutralize" on page : "oppose and neutralize." moved the semi-colon inside the double quotes on page , around: "corresponding points." changed "thompson's" to "thomson's" in the chapter heading on page : "thomson's theory." changed "last" to "least" in the footnote to page : "at least as anxious." changed "i" to "it" on page : "it was also." "die gletscher der jetzzeit" on page should probably be "die gletscher der jetztzeit," but was not changed. inserted a comma in the index entry for "aletsch glacier:" "-- --, bedding." inserted a comma in the index entry for "dirt-bands:" "-- --, maps of." changed "goutér" to "goûter" in the index entry for "dôme du goûter." changed "hoch-joch" to "hochjoch" in its index entry. inserted second em-dash in the index entry for "mont blanc:" "-- --, second ascent of." inserted a comma in the index entry for "rays:" "--, transmission of." inserted a comma in the index entry for "strahleck:" "--, passage of." [transcriber's note: _text_ and =text= represent italic and bold text respectively. subscripts are displayed as an underscore followed by the number or text in braces: sio_{ }.] * * * * * [illustration: a valley with rocky ledges cut in the horizontal strata, scotland] the elements of geology by william harmon norton professor of geology in cornell college ginn & company boston * new york * chicago * london copyright, , , by william harmon norton all rights reserved the atheneum press ginn & company proprietors boston * u.s.a. preface geology is a science of such rapid growth that no apology is expected when from time to time a new text-book is added to those already in the field. the present work, however, is the outcome of the need of a text-book of very simple outline, in which causes and their consequences should be knit together as closely as possible,--a need long felt by the author in his teaching, and perhaps by other teachers also. the author has ventured, therefore, to depart from the common usage which subdivides geology into a number of departments,--dynamical, structural, physiographic, and historical,--and to treat in immediate connection with each geological process the land forms and the rock structures which it has produced. it is hoped that the facts of geology and the inferences drawn from them have been so presented as to afford an efficient discipline in inductive reasoning. typical examples have been used to introduce many topics, and it has been the author's aim to give due proportion to both the wide generalizations of our science and to the concrete facts on which they rest. there have been added a number of practical exercises such as the author has used for several years in the class room. these are not made so numerous as to displace the problems which no doubt many teachers prefer to have their pupils solve impromptu during the recitation, but may, it is hoped, suggest their use. in historical geology a broad view is given of the development of the north american continent and the evolution of life upon the planet. only the leading types of plants and animals are mentioned, and special attention is given to those which mark the lines of descent of forms now living. by omitting much technical detail of a mineralogical and palæontological nature, and by confining the field of view almost wholly to our own continent, space has been obtained to give to what are deemed for beginners the essentials of the science a fuller treatment than perhaps is common. it is assumed that field work will be introduced with the commencement of the study. the common rocks are therefore briefly described in the opening chapters. the drift also receives early mention, and teachers in the northern states who begin geology in the fall may prefer to take up the chapter on the pleistocene immediately after the chapter on glaciers. simple diagrams have been used freely, not only because they are often clearer than any verbal statement, but also because they readily lend themselves to reproduction on the blackboard by the pupil. the text will suggest others which the pupil may invent. it is hoped that the photographic views may also be used for exercises in the class room. the generous aid of many friends is recognized with special pleasure. to professor w. m. davis of harvard university there is owing a large obligation for the broad conceptions and luminous statements of geologic facts and principles with which he has enriched the literature of our science, and for his stimulating influence in education. it is hoped that both in subject-matter and in method the book itself makes evident this debt. but besides a general obligation shared by geologists everywhere, and in varying degrees by perhaps all authors of recent american text-books in earth science, there is owing a debt direct and personal. the plan of the book, with its use of problems and treatment of land forms and rock structures in immediate connection with the processes which produce them, was submitted to professor davis, and, receiving his approval, was carried into effect, although without the sanction of precedent at the time. professor davis also kindly consented to read the manuscript throughout, and his many helpful criticisms and suggestions are acknowledged with sincere gratitude. parts of the manuscript have been reviewed by dr. samuel calvin and dr. frank m. wilder of the state university of iowa; dr. s. w. beyer of the iowa college of agriculture and mechanic arts; dr. u. s. grant of northwestern university; professor j. a. udden of augustana college, illinois; dr. c. h. gordon of the new mexico state school of mines; principal maurice ricker of the high school, burlington, iowa; and the following former students of the author who are engaged in the earth sciences: dr. w. c. alden of the united states geological survey and the university of chicago; mr. joseph sniffen, instructor in the academy of the university of chicago, morgan park; professor martin iorns, fort worth university, texas; professor a. m. jayne, dakota university; professor g. h. bretnall, monmouth college, illinois; professor howard e. simpson, colby college, maine; mr. e. j. cable, instructor in the iowa state normal college; principal c. c. gray of the high school, fargo, north dakota; and mr. charles persons of the high school, hannibal, missouri. a large number of the diagrams of the book were drawn by mr. w. w. white of the art school of cornell college. to all these friends, and to the many who have kindly supplied the illustrations of the text, whose names are mentioned in an appended list, the writer returns his heartfelt thanks. william harmon norton cornell college, mount vernon, iowa july, introductory note during the preparation of this book professor norton has frequently discussed its plan with me by correspondence, and we have considered together the matters of scope, arrangement, and presentation. as to scope, the needs of the young student and not of the expert have been our guide; the book is therefore a text-book, not a reference volume. in arrangement, the twofold division of the subject was chosen because of its simplicity and effectiveness. the principles of physical geology come first; the several chapters are arranged in what is believed to be a natural order, appropriate to the greatest part of our country, so that from a simple beginning a logical sequence of topics leads through the whole subject. the historical view of the science comes second, with many specific illustrations of the physical processes previously studied, but now set forth as part of the story of the earth, with its many changes of aspect and its succession of inhabitants. special attention is here given to north america, and care is taken to avoid overloading with details. with respect to method of presentation, it must not be forgotten that the text-book is only one factor in good teaching, and that in geology, as in other sciences, the teacher, the laboratory, and the local field are other factors, each of which should play an appropriate part. the text suggests observational methods, but it cannot replace observation in field or laboratory; it offers certain exercises, but space cannot be taken to make it a laboratory manual as well as a book for study; it explains many problems, but its statements are necessarily more terse than the illustrative descriptions that a good and experienced teacher should supply. frequent use is made of induction and inference in order that the student may come to see how reasonable a science is geology, and that he may avoid the too common error of thinking that the opinions of "authorities" are reached by a private road that is closed to him. the further extension of this method of presentation is urged upon the teacher, so that the young geologist may always learn the evidence that leads to a conclusion, and not only the conclusion itself. w. m. davis harvard university, cambridge, mass. july, acknowledgment of illustrations adams, professor f. d., mcgill university, canada, . alden, dr. w. c., washington, d.c., . american museum of natural history, new york, . ash, h. c., galesburg, ill., . beyer, dr. s. w., iowa college of agriculture, . calvin, dr. samuel, iowa state university, , , , , . carney, frank, ithaca, n.y., . clark, dr. wm. b., maryland geological survey, . borne, dr. georg v. d., jena, germany, , . daly, dr. r. a., ottawa, canada, . defieux, c. a., liverpool, england, . * detroit photographic co., , . * ellis, w. m., edna, kan., . fairchild, professor h. l., university of rochester, , . field columbian museum, chicago, . forster, dr. a. e., university of vienna, . gardner, j. l., boston, , , . geological survey of canada, . gilbert, dr. g. k., by courtesy of the american book company, . * haines, ben, new albany, ind., . * haynes, f. j., st. paul, minn., , , . henderson, judge julius, boulder, col., . james, george wharton, pasadena, cal., , , , . johnston-lavis, professor h. j., beaulieu, france, . king, j. harding, stourbridge, england, . lawson, dr. andrew c., university of california, . le conte, professor j. n., university of california, . libbey, dr. william, princeton university, . * mcallister, t. h., new york, . * meyers, h. c., boise, id., . mills, professor h. a., cornell college, , . norton, professor w. h., cornell college, , , , , , , , , , , , . * notman, wm. & son, montreal, canada, , . obrutschew, dr. w., tomsk technological institute, siberia, . oldham, dr. r. d., geological survey of india, . * peabody, h. c., pasadena, cal., . * pierce, c. c. & co., los angeles, cal., . pillsbury, arthur, san francisco, cal., . . * rau, wm., philadelphia, , , , , . reusch, dr. hans, geological survey of norway, . reynolds, professor s. h., university college, bristol, england, . ricker, principal maurice, burlington, iowa, , . * shepard, e. a., minneapolis, minn., . smith, w. s. tangier, los gatos, cal., . * soule photographic co., boston, . u. s. geological survey, , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , . u. s. national museum, , , , , , . * valentine & sons, dundee, scotland, , , . vroman, a. c., pasadena, cal., . * ward's natural science establishment, rochester, n.y., . * welch, r., belfast, ireland, , . * westgate, dr. l. g., ohio wesleyan university, . whymper, edward, london, england, . * wilcox, w. d., washington, d.c., . * wilson, dr. a. w. g., mcgill university, canada, . * wilson, g. w., & co., aberdeen, scotland, , . * worsley-benison, f. h., cheapstow, england, . * dealer in photographs or lantern slides. contents page introduction.--the scope and aim of geology part i external geological agencies chapter i. the work of the weather ii. the work of ground water iii. rivers and valleys iv. river deposits v. the work of glaciers vi. the work of the wind vii. the sea and its shores viii. offshore and deep-sea deposits part ii internal geological agencies ix. movements of the earth's crust x. earthquakes xi. volcanoes xii. underground structures of igneous origin xiii. metamorphism and mineral veins part iii historical geology xiv. the geological record xv. the pre-cambrian systems xvi. the cambrian xvii. the ordovician and silurian xviii. the devonian xix. the carboniferous xx. the mesozoic xxi. the tertiary xxii. the quaternary index the elements of geology introduction the scope and aim of geology geology deals with the rocks of the earth's crust. it learns from their composition and structure how the rocks were made and how they have been modified. it ascertains how they have been brought to their present places and wrought to their various topographic forms, such as hills and valleys, plains and mountains. it studies the vestiges which the rocks preserve of ancient organisms which once inhabited our planet. geology is the history of the earth and its inhabitants, as read in the rocks of the earth's crust. to obtain a general idea of the nature and method of our science before beginning its study in detail, we may visit some valley, such as that illustrated in the frontispiece, on whose sides are rocky ledges. here the rocks lie in horizontal layers. although only their edges are exposed, we may infer that these layers run into the upland on either side and underlie the entire district; they are part of the foundation of solid rock which everywhere is found beneath the loose materials of the surface. the ledges of the valley of our illustration are of sandstone. looking closely at the rock we see that it is composed of myriads of grains of sand cemented together. these grains have been worn and rounded. they are sorted also, those of each layer being about of a size. by some means they have been brought hither from some more ancient source. surely these grains have had a history before they here found a resting place,--a history which we are to learn to read. the successive layers of the rock suggest that they were built one after another from the bottom upward. we may be as sure that each layer was formed before those above it as that the bottom courses of stone in a wall were laid before the courses which rest upon them. we have no reason to believe that the lowest layers which we see here were the earliest ever formed. indeed, some deep boring in the vicinity may prove that the ledges rest upon other layers of rock which extend downward for many hundreds of feet below the valley floor. nor may we conclude that the highest layers here were the latest ever laid; for elsewhere we may find still later layers lying upon them. a short search may find in the rock relics of animals, such as the imprints of shells, which lived when it was deposited; and as these are of kinds whose nearest living relatives now have their home in the sea, we infer that it was on the flat sea floor that the sandstone was laid. its present position hundreds of feet above sea level proves that it has since emerged to form part of the land; while the flatness of the beds shows that the movement was so uniform and gentle as not to break or strongly bend them from their original attitude. the surface of some of these layers is ripple-marked. hence the sand must once have been as loose as that of shallow sea bottoms and sea beaches to-day, which is thrown into similar ripples by movements of the water. in some way the grains have since become cemented into firm rock. note that the layers on one side of the valley agree with those on the other, each matching the one opposite at the same level. once they were continuous across the valley. where the valley now is was once a continuous upland built of horizontal layers; the layers now show their edges, or _outcrop_, on the valley sides because they have been cut by the valley trench. the rock of the ledges is crumbling away. at the foot of each step of rock lie fragments which have fallen. thus the valley is slowly widening. it has been narrower in the past; it will be wider in the future. through the valley runs a stream. the waters of rains which have fallen on the upper parts of the stream's basin are now on their way to the river and the sea. rock fragments and grains of sand creeping down the valley slopes come within reach of the stream and are washed along by the running water. here and there they lodge for a time in banks of sand and gravel, but sooner or later they are taken up again and carried on. the grains of sand which were brought from some ancient source to form these rocks are on their way to some new goal. as they are washed along the rocky bed of the stream they slowly rasp and wear it deeper. the valley will be deeper in the future; it has been less deep in the past. in this little valley we see slow changes now in progress. we find also in the composition, the structure, and the attitude of the rocks, and the land forms to which they have been sculptured, the record of a long succession of past changes involving the origin of sand grains and their gathering and deposit upon the bottom of some ancient sea, the cementation of their layers into solid rock, the uplift of the rocks to form a land surface, and, last of all, the carving of a valley in the upland. everywhere, in the fields, along the river, among the mountains, by the seashore, and in the desert, we may discover slow changes now in progress and the record of similar changes in the past. everywhere we may catch glimpses of a process of gradual change, which stretches backward into the past and forward into the future, by which the forms and structures of the face of the earth are continually built and continually destroyed. the science which deals with this long process is geology. geology treats of the natural changes now taking place upon the earth and within it, the agencies which produce them, and the land forms and rock structures which result. it studies the changes of the present in order to be able to read the history of the earth's changes in the past. the various agencies which have fashioned the face of the earth may. be divided into two general classes. in part i we shall consider those which work upon the earth from without, such as the weather, running water, glaciers, the wind, and the sea. in part ii we shall treat of those agencies whose sources are within the earth, and among whose manifestations are volcanoes and earthquakes and the various movements of the earth's crust. as we study each agency we shall notice not only how it does its work, but also the records which it leaves in the rock structures and the land forms which it produces. with this preparation we shall be able in part iii to read in the records of the rocks the history of our planet and the successive forms of life which have dwelt upon it. part i external geological agencies chapter i the work of the weather in our excursion to the valley with sandstone ledges we witnessed a process which is going forward in all lands. everywhere the rocks are crumbling away; their fragments are creeping down hillsides to the stream ways and are carried by the streams to the sea, where they are rebuilt into rocky layers. when again the rocks are lifted to form land the process will begin anew; again they will crumble and creep down slopes and be washed by streams to the sea. let us begin our study of this long cycle of change at the point where rocks disintegrate and decay under the action of the weather. in studying now a few outcrops and quarries we shall learn a little of some common rocks and how they weather away. =stratification and jointing.= at the sandstone ledges we saw that the rock was divided into parallel layers. the thicker layers are known as _strata_, and the thin leaves into which each stratum may sometimes be split are termed _laminæ_. to a greater or less degree these layers differ from each other in fineness of grain, showing that the material has been sorted. the planes which divide them are called _bedding planes_. besides the bedding planes there are other division planes, which cut across the strata from top to bottom. these are found in all rocks and are known as _joints_ (fig. ). two sets of joints, running at about right angles to each other, together with the bedding planes, divide the sandstone into quadrangular blocks. [illustration: fig. . cliff of sandstone, ireland] =sandstone.= examining a piece of sandstone we find it composed of grains quite like those of river sand or of sea beaches. most of the grains are of a clear glassy mineral called quartz. these quartz grains are very hard and will scratch the steel of a knife blade. they are not affected by acid, and their broken surfaces are irregular like those of broken glass. the grains of sandstone are held together by some cement. this may be _calcareous_, consisting of soluble carbonate of lime. in brown sandstones the cement is commonly _ferruginous_,--hydrated iron oxide, or iron rust, forming the bond, somewhat as in the case of iron nails which have rusted together. the strongest and most lasting cement is _siliceous_, and sand rocks whose grains are closely cemented by silica, the chemical substance of which quartz is made, are known as quartzites. we are now prepared to understand how sandstone is affected by the action of the weather. on ledges where the rock is exposed to view its surface is more or less discolored and the grains are loose and may be rubbed off with the finger. on gentle slopes the rock is covered with a soil composed of sand, which evidently is crumbled sandstone, and dark carbonaceous matter derived from the decay of vegetation. clearly it is by the dissolving of the cement that the rock thus breaks down to loose sand. a piece of sandstone with calcareous cement, or a bit of old mortar, which is really an artificial stone also made of sand cemented by lime, may be treated in a test tube with hydrochloric acid to illustrate the process. [illustration: fig. . section of limestone quarry scale, in. = ft. _a_, red residual clay; _mn_, pitted surface of rotted limestone; _bb_, limestone divided into thin layers; _c_, thick layers of laminated limestone, the laminæ being firmly cemented together; _j_, _j_, _j_, joints. is _bb_ thin-layered because originally so laid, or because it has been broken up by weathering, although once like _c_ thick-layered?] a limestone quarry. here also we find the rock stratified and jointed (fig. ). on the quarry face the rock is distinctly seen to be altered for some distance from its upper surface. below the altered zone the rock is sound and is quarried for building; but the altered upper layers are too soft and broken to be used for this purpose. if the limestone is laminated, the laminae here have split apart, although below they hold fast together. near the surface the stone has become rotten and crumbles at the touch, while on the top it has completely broken down to a thin layer of limestone meal, on which rests a fine reddish clay. limestone is made of minute grains of carbonate of lime all firmly held together by a calcareous cement. a piece of the stone placed in a test tube with hydrochloric acid dissolves with brisk effervescence, leaving the insoluble impurities, which were disseminated through it, at the bottom of the tube as a little clay. we can now understand the changes in the upper layers of the quarry. at the surface of the rock the limestone has completely dissolved, leaving the insoluble residue as a layer of reddish clay. immediately below the clay the rock has disintegrated into meal where the cement between the limestone grains has been removed, while beneath this the laminae are split apart where the cement has been dissolved only along the planes of lamination where the stone is more porous. as these changes in the rock are greatest at the surface and diminish downward, we infer that they have been caused by agents working downward from the surface. at certain points these agencies have been more effective than elsewhere. the upper rock surface is pitted. joints are widened as they approach the surface, and along these seams we may find that the rock is altered even down to the quarry floor. =a shale pit.= let us now visit some pit where shale--a laminated and somewhat hardened clay--is quarried for the manufacture of brick. the laminae of this fine-grained rock may be as thin as cardboard in places, and close joints may break the rock into small rhombic blocks. on the upper surface we note that the shale has weathered to a clayey soil in which all traces of structure have been destroyed. the clay and the upper layers of the shale beneath it are reddish or yellow, while in many cases the color of the unaltered rock beneath is blue. =the sedimentary rocks.= the three kinds of layered rocks whose acquaintance we have made--sandstone, limestone, and shale--are the leading types of the great group of stratified, or sedimentary, rocks. this group includes all rocks made of sediments, their materials having settled either in water upon the bottoms of rivers, lakes, or seas, or on dry land, as in the case of deposits made by the wind and by glaciers. sedimentary rocks are divided into the fragmental rocks--which are made of fragments, either coarse or fine--and the far less common rocks which are constituted of chemical precipitates. [illustration: fig. . conglomerate] the sedimentary rocks are divided according to their composition into the following classes: . the arenaceous, or quartz rocks, including beds of loose sand and gravel, sandstone, quartzite, and conglomerate (a rock made of cemented rounded gravel or pebbles). . the calcareous, or lime rocks, including limestone and a soft white rock formed of calcareous powder known as chalk. . the argillaceous, or clay rocks, including muds, clays, and shales. these three classes pass by mixture into one another. thus there are limy and clayey sandstones, sandy and clayey limestones, and sandy and limy shales. =granite.= this familiar rock may be studied as an example of the second great group of rocks,--_the unstratified_, or _igneous rocks_. these are not made of cemented sedimentary grains, but of interlocking crystals which have crystallized from a molten mass. examining a piece of granite, the most conspicuous crystals which meet the eye are those of feldspar. they are commonly pink, white, or yellow, and break along smooth cleavage planes which reflect the light like tiny panes of glass. mica may be recognized by its glittering plates, which split into thin elastic scales. a third mineral, harder than steel, breaking along irregular surfaces like broken glass, we identify as quartz. how granite alters under the action of the weather may be seen in outcrops where it forms the bed rock, or country rock, underlying the loose formations of the surface, and in many parts of the northern states where granite bowlders and pebbles more or less decayed may be found in a surface sheet of stony clay called the drift. of the different minerals composing granite, quartz alone remains unaltered. mica weathers to detached flakes which have lost their elasticity. the feldspar crystals have lost their luster and hardness, and even have decayed to clay. where long-weathered granite forms the country rock, it often may be cut with spade or trowel for several feet from the surface, so rotten is the feldspar, and here the rock is seen to break down to a clayey soil containing grains of quartz and flakes of mica. these are a few simple illustrations of the surface changes which some of the common kinds of rocks undergo. the agencies by which these changes are brought about we will now take up under two divisions,--_chemical agencies_ producing rock decay and _mechanical agencies_ producing rock disintegration. the chemical work of water as water falls on the earth in rain it has already absorbed from the air carbon dioxide (carbonic acid gas) and oxygen. as it sinks into the ground and becomes what is termed ground water, it takes into solution from the soil humus acids and carbon dioxide, both of which are constantly being generated there by the decay of organic matter. so both rain and ground water are charged with active chemical agents, by the help of which they corrode and rust and decompose all rocks to a greater or less degree. we notice now three of the chief chemical processes concerned in weathering,--solution, the formation of carbonates, and oxidation. =solution.= limestone, although so little affected by pure water that five thousand gallons would be needed to dissolve a single pound, is easily dissolved in water charged with carbon dioxide. in limestone regions well water is therefore "hard." on boiling the water for some time the carbon dioxide gas is expelled, the whole of the lime carbonate can no longer be held in solution, and much of it is thrown down to form a crust or "scale" in the kettle or in the tubes of the steam boiler. all waters which flow over limestone rocks or soak through them are constantly engaged in dissolving them away, and in the course of time destroy beds of vast extent and great thickness. [illustration: fig. . surface of limestone furrowed by weathering, montana] the upper surface of limestone rocks becomes deeply pitted, as we saw in the limestone quarry, and where the mantle of waste has been removed it may be found so intricately furrowed that it is difficult to traverse (fig. ). beds of _rock salt_ buried among the strata are dissolved by seeping water, which issues in salt springs. _gypsum_, a mineral composed of hydrated sulphate of lime, and so soft that it may be scratched with the finger nail, is readily taken up by water, giving to the water of wells and springs a peculiar hardness difficult to remove. the dissolving action of moisture may be noted on marble tombstones of some age, marble being a limestone altered by heat and pressure and composed of crystalline grains. by assuming that the date on each monument marks the year of its erection, one may estimate how many years on the average it has taken for weathering to loosen fine grains on the polished surface, so that they may be rubbed off with the finger, to destroy the polish, to round the sharp edges of tool marks in the lettering, and at last to open cracks and seams and break down the stone. we may notice also whether the gravestones weather more rapidly on the sunny or the shady side, and on the sides or on the top. the weathered surface of granular limestone containing shells shows them standing in relief. as the shells are made of crystalline carbonate of lime, we may infer whether the carbonate of lime is less soluble in its granular or in its crystalline condition. =the formation of carbonates.= in attacking minerals water does more than merely take them into solution. it decomposes them, forming new chemical compounds of which the carbonates are among the most important. thus feldspar consists of the insoluble silicate of alumina, together with certain alkaline silicates which are broken up by the action of water containing carbon dioxide, forming alkaline carbonates. these carbonates are freely soluble and contribute potash and soda to soils and river waters. by the removal of the soluble ingredients of feldspar there is left the silicate of alumina, united with water or hydrated, in the condition of a fine plastic clay which, when white and pure, is known as _kaolin_ and is used in the manufacture of porcelain. feldspathic rocks which contain no iron compounds thus weather to whitish crusts, and even apparently sound crystals of feldspar, when ground to thin slices and placed under the microscope, may be seen to be milky in color throughout because an internal change to kaolin has begun. [illustration: fig. . bowlder split by heat and cold, western texas] =oxidation.= rocks containing compounds of iron weather to reddish crusts, and the seams of these rocks are often lined with rusty films. oxygen and water have here united with the iron, forming hydrated iron oxide. the effects of oxidation may be seen in the alteration of many kinds of rocks and in red and yellow colors of soils and subsoils. _pyrite_ is a very hard mineral of a pale brass color, found in scattered crystals in many rocks, and is composed of iron and sulphur (iron sulphide). under the attack of the weather it takes up oxygen, forming iron sulphate (green vitriol), a soluble compound, and insoluble hydrated iron oxide, which as a mineral is known as limonite. several large masses of iron sulphide were placed some years ago on the lawn in front of the national museum at washington. the mineral changed so rapidly to green vitriol that enough of this poisonous compound was washed into the ground to kill the roots of the surrounding grass. agents of mechanical disintegration =heat and cold.= rocks exposed to the direct rays of the sun become strongly heated by day and expand. after sunset they rapidly cool and contract. when the difference in temperature between day and night is considerable, the repeated strains of sudden expansion and contraction at last become greater than the rocks can bear, and they break, for the same reason that a glass cracks when plunged into boiling water (fig. ). rocks are poor conductors of heat, and hence their surfaces may become painfully hot under the full blaze of the sun, while the interior remains comparatively cool. by day the surface shell expands and tends to break loose from the mass of the stone. in cooling in the evening the surface shell suddenly contracts on the unyielding interior and in time is forced off in scales (fig. ). [illustration: fig. . bowlders scaling off under heat and cold, western texas] many rocks, such as granite, are made up of grains of various minerals which differ in color and in their capacity to absorb heat, and which therefore contract and expand in different ratios. in heating and cooling these grains crowd against their neighbors and tear loose from them, so that finally the rock disintegrates into sand. the conditions for the destructive action of heat and cold are most fully met in arid regions when vegetation is wanting for lack of sufficient rain. the soil not being held together by the roots of plants is blown away over large areas, leaving the rocks bare to the blazing sun in a cloudless sky. the air is dry, and the heat received by the earth by day is therefore rapidly radiated at night into space. there is a sharp and sudden fall of temperature after sunset, and the rocks, strongly heated by day, are now chilled perhaps even to the freezing point. in the sahara the thermometer has been known to fall ° f. within a few hours. in the light air of the pamir plateau in central asia a rise of ° f. has been recorded from seven o'clock in the morning to one o'clock in the afternoon. on the mountains of southwestern texas there are frequently heard crackling noises as the rocks of that arid region throw off scales from a fraction of an inch to four inches in thickness, and loud reports are made as huge bowlders split apart. desert pebbles weakened by long exposure to heat and cold have been shivered to fine sharp-pointed fragments on being placed in sand heated to degrees f. beds half a foot thick, forming the floor of limestone quarries in wisconsin, have been known to buckle and arch and break to fragments under the heat of the summer sun. =frost.= by this term is meant the freezing and thawing of water contained in the pores and crevices of rocks. all rocks are more or less porous and all contain more or less water in their pores. workers in stone call this "quarry water," and speak of a stone as "green" before the quarry water has dried out. water also seeps along joints and bedding planes and gathers in all seams and crevices. water expands in freezing, ten cubic inches of water freezing to about eleven cubic inches of ice. as water freezes in the rifts and pores of rocks it expands with the irresistible force illustrated in the freezing and breaking of water pipes in winter. the first rift in the rock, perhaps too narrow to be seen, is widened little by little by the wedges of successive frosts, and finally the rock is broken into detached blocks, and these into angular chip-stone by the same process. it is on mountain tops and in high latitudes that the effects of frost are most plainly seen. "every summit" says whymper, "amongst the rock summits upon which i have stood has been nothing but a piled-up heap of fragments" (fig. ). in iceland, in spitzbergen, in kamchatka, and in other frigid lands large areas are thickly strewn with sharp-edged fragments into which the rock has been shattered by frost. [illustration: fig. . rocks broken by frost, summit of the eggischhorn, switzerland] =organic agents.= we must reckon the roots of plants and trees among the agents which break rocks into pieces. the tiny rootlet in its search for food and moisture inserts itself into some minute rift, and as it grows slowly wedges the rock apart. moreover, the acids of the root corrode the rocks with which they are in contact. one may sometimes find in the soil a block of limestone wrapped in a mesh of roots, each of which lies in a little furrow where it has eaten into the stone. rootless plants called _lichens_ often cover and corrode rocks as yet bare of soil; but where lichens are destroying the rock less rapidly than does the weather, they serve in a way as a protection. =conditions favoring disintegration and decay.= the disintegration of rocks under frost and temperature changes goes on most rapidly in cold and arid climates, and where vegetation is scant or absent. on the contrary, the decay of rocks under the chemical action of water is favored by a warm, moist climate and abundant vegetation. frost and heat and cold can only act within the few feet from the surface to which the necessary temperature changes are limited, while water penetrates and alters the rocks to great depths. the pupil may explain. in what ways the presence of joints and bedding planes assists in the breaking up and decay of rocks under the action of the weather. why it is a good rule of stone masons never to lay stones on edge, but always on their natural bedding planes. why stones fresh from the quarry sometimes go to pieces in early winter, when stones which have been quarried for some months remain uninjured. why quarrymen in the northern states often keep their quarry floors flooded during winter. why laminated limestone should not be used for curbstone. why rocks composed of layers differing in fineness of grain and in ratios of expansion do not make good building stone. fine-grained rocks with pores so small that capillary attraction keeps the water which they contain from readily draining away are more apt to hold their pores ten elevenths full of water than are rocks whose pores are larger. which, therefore, are more likely to be injured by frost? which is subject to greater temperature changes, a dark rock or one of a light color? the north side or the south side of a valley? the mantle of rock waste we have seen that rocks are everywhere slowly wasting away. they are broken in pieces by frost, by tree roots, and by heat and cold. they dissolve and decompose under the chemical action of water and the various corrosive substances which it contains, leaving their insoluble residues as residual clays and sands upon the surface. as a result there is everywhere forming a mantle of rock waste which covers the land. it is well to imagine how the country would appear were this mantle with its soil and vegetation all scraped away or had it never been formed. the surface of the land would then be everywhere of bare rock as unbroken as a quarry floor. =the thickness of the mantle.= in any locality the thickness of the mantle of rock waste depends as much on the rate at which it is constantly being removed as on the rate at which it is forming. on the face of cliffs it is absent, for here waste is removed as fast as it is made. where waste is carried away more slowly than it is produced, it accumulates in time to great depth. the granite of pikes peak is disintegrated to a depth of twenty feet. in the city of washington granite rock is so softened to a depth of eighty feet that it can be removed with pick and shovel. about atlanta, georgia, the rocks are completely rotted for one hundred feet from the surface, while the beginnings of decay may be noticed at thrice that depth. in places in southern brazil the rock is decomposed to a depth of four hundred feet. in southwestern wisconsin a reddish residual clay has an average depth of thirteen feet on broad uplands, where it has been removed to the least extent. the country rock on which it rests is a limestone with about ten per cent of insoluble impurities. at least how thick, then, was that portion of the limestone which has rotted down to the clay? =distinguishing characteristics of residual waste.= we must learn to distinguish waste formed in place by the action of the weather from the products of other geological agencies. residual waste is unstratified. it contains no substances which have not been derived from the weathering of the parent rock. there is a gradual transition from residual waste into the unweathered rock beneath. waste resting on sound rock evidently has been shifted and was not formed in place. in certain regions of southern missouri the land is covered with a layer of broken flints and red clay, while the country rock is limestone. the limestone contains nodules of flint, and we may infer that it has been by the decay and removal of thick masses of limestone that the residual layer of clay and flints has been left upon the surface. flint is a form of quartz, dull-lustered, usually gray or blackish in color, and opaque except on thinnest edges, where it is translucent. over much of the northern states there is spread an unstratified stony clay called the _drift_. it often rests on sound rocks. it contains grains of sand, pebbles, and bowlders composed of many different minerals and rocks that the country rock cannot furnish. hence the drift cannot have been formed by the decay of the rock of the region. a shale or limestone, for example, cannot waste to a clay containing granite pebbles. the origin of the drift will be explained in subsequent chapters. the differences in rocks are due more to their soluble than to their insoluble constituents. the latter are few in number and are much the same in rocks of widely different nature, being chiefly quartz, silicate of alumina, and iron oxide. by the removal of their soluble parts very many and widely different rocks rot down to a residual clay gritty with particles of quartz and colored red or yellow with iron oxide. in a broad way the changes which rocks undergo in weathering are an adaptation to the environment in which they find themselves at the earth's surface,--an environment different from that in which they were formed under sea or under ground. in open air, where they are attacked by various destructive agents, few of the rock-making minerals are stable compounds except quartz, the iron oxides, and the silicate of alumina; and so it is to one or more of these comparatively insoluble substances that most rocks are reduced by long decay. which produces a mantle of finer waste, frost or chemical decay? which a thicker mantle? in what respects would you expect that the mantle of waste would differ in warm humid lands like india, in frozen countries like alaska, and in deserts such as the sahara? =the soil.= the same agencies which produce the mantle of waste are continually at work upon it, breaking it up into finer and finer particles and causing its more complete decay. thus on the surface, where the waste has weathered longest, it is gradually made fine enough to support the growth of plants, and is then known as _soil_. the coarser waste beneath is sometimes spoken of as subsoil. soil usually contains more or less dark, carbonaceous, decaying organic matter, called humus, and is then often termed the _humus layer_. soil forms not only on waste produced in place from the rock beneath, but also on materials which have been transported, such as sheets of glacial drift and river deposits. until rocks are reduced to residual clays the work of the weather is more rapid and effective on the fragments of the mantle of waste than on the rocks from which waste is being formed. why? any fresh excavation of cellar or cistern, or cut for road or railway, will show the characteristics of the humus layer. it may form only a gray film on the surface, or we may find it a layer a foot or more thick, dark, or even black, above, and growing gradually lighter in color as it passes by insensible gradations into the subsoil. in some way the decaying vegetable matter continually forming on the surface has become mingled with the material beneath it. =how humus and the subsoil are mingled.= the mingling of humus and the subsoil is brought about by several means. the roots of plants penetrate the waste, and when they die leave their decaying substance to fertilize it. leaves and stems falling on the surface are turned under by several agents. earthworms and other animals whose home is in the waste drag them into their burrows either for food or to line their nests. trees overthrown by the wind, roots and all, turn over the soil and subsoil and mingle them together. bacteria also work in the waste and contribute to its enrichment. the animals living in the mantle do much in other ways toward the making of soil. they bring the coarser fragments from beneath to the surface, where the waste weathers more rapidly. their burrows allow air and water to penetrate the waste more freely and to affect it to greater depths. =ants.= in the tropics the mantle of waste is worked over chiefly by ants. they excavate underground galleries and chambers, extending sometimes as much as fourteen feet below the surface, and build mounds which may reach as high above it. in some parts of paraguay and southern brazil these mounds, like gigantic potato hills, cover tracts of considerable area. in search for its food--the dead wood of trees--the so-called white ant constructs runways of earth about the size of gas pipes, reaching from the base of the tree to the topmost branches. on the plateaus of central africa explorers have walked for miles through forests every tree of which was plastered with these galleries of mud. each grain of earth used in their construction is moistened and cemented by slime as it is laid in place by the ant, and is thus acted on by organic chemical agents. sooner or later these galleries are beaten down by heavy rains, and their fertilizing substances are scattered widely by the winds. =earthworms.= in temperate regions the waste is worked over largely by earthworms. in making their burrows worms swallow earth in order to extract from it any nutritive organic matter which it may contain. they treat it with their digestive acids, grind it in their stony gizzards, and void it in castings on the surface of the ground. it was estimated by darwin that in many parts of england each year, on every acre, more than ten tons of earth pass through the bodies of earthworms and are brought to the surface, and that every few years the entire soil layer is thus worked over by them. in all these ways the waste is made fine and stirred and enriched. grain by grain the subsoil with its fresh mineral ingredients is brought to the surface, and the rich organic matter which plants and animals have taken from the atmosphere is plowed under. thus nature plows and harrows on "the great world's farm" to make ready and ever to renew a soil fit for the endless succession of her crops. the world processes by which rocks are continually wasting away are thus indispensable to the life of plants and animals. the organic world is built on the ruins of the inorganic, and because the solid rocks have been broken down into soil men are able to live upon the earth. =solar energy.= the source of the energy which accomplishes all this necessary work is the sun. it is the radiant energy of the sun which causes the disintegration of rocks, which lifts vapor into the atmosphere to fall as rain, which gives life to plants and animals. considering the earth in a broad way, we may view it as a globe of solid rock,--_the lithosphere_,--surrounded by two mobile envelopes: the envelope of air,--_the atmosphere_; and the envelope of water,--_the hydrosphere_. under the action of solar energy these envelopes are in constant motion. water from the hydrosphere is continually rising in vapor into the atmosphere, the air of the atmosphere penetrates the hydrosphere,--for its gases are dissolved in all waters,--and both air and water enter and work upon the solid earth. by their action upon the lithosphere they have produced a third envelope,--the mantle of rock waste. this envelope also is in movement, not indeed as a whole, but particle by particle. the causes which set its particles in motion, and the different forms which the mantle comes to assume, we will now proceed to study. movements of the mantle of rock waste at the sandstone ledges which we first visited we saw not only that the rocks were crumbling away, but also that grains and fragments of them were creeping down the slopes of the valley to the stream and were carried by it onward toward the sea. this process is going on everywhere. slowly it may be, and with many interruptions, but surely, the waste of the land moves downward to the sea. we may divide its course into two parts,--the path to the stream, which we will now consider, and its carriage onward by the stream, which we will defer to a later chapter. =gravity.= the chief agent concerned in the movement of waste is gravity. each particle of waste feels the unceasing downward pull of the earth's mass and follows it when free to do so. all agencies which produce waste tend to set its particles free and in motion, and therefore coöperate with gravity. on cliffs, rocks fall when wedged off by frost or by roots of trees, and when detached by any other agency. on slopes of waste, water freezes in chinks between stones, and in pores between particles of soil, and wedges them apart. animals and plants stir the waste, heat expands it, cold contracts it, the strokes of the raindrops drive loose particles down the slope and the wind lifts and lets them fall. of all these movements, gravity assists those which are downhill and retards those which are uphill. on the whole, therefore, the downhill movements prevail, and the mantle of waste, block by block and grain by grain, creeps along the downhill path. a slab of sandstone laid on another of the same kind at an angle of ° and left in the open air was found to creep down the slope at the rate of a little more than a millimeter a month. explain why it did so. =rain.= the most efficient agent in the carriage of waste to the streams is the rain. it moves particles of soil by the force of the blows of the falling drops, and washes them down all slopes to within reach of permanent streams. on surfaces unprotected by vegetation, as on plowed fields and in arid regions, the rain wears furrows and gullies both in the mantle of waste and in exposures of unaltered rock (fig. ). at the foot of a hill we may find that the soil has accumulated by creep and wash to the depth of several feet; while where the hillside is steepest the soil may be exceedingly thin, or quite absent, because removed about as fast as formed. against the walls of an abbey built on a slope in wales seven hundred years ago, the creeping waste has gathered on the uphill side to a depth of seven feet. the slow-flowing sheet of waste is often dammed by fences and walls, whose uphill side gathers waste in a few years so as to show a distinctly higher surface than the downhill side, especially in plowed fields where the movement is least checked by vegetation. =talus.= at the foot of cliffs there is usually to be found a slope of rock fragments which clearly have fallen from above (fig. ). such a heap of waste is known as _talus_. the amount of talus in any place depends both on the rate of its formation and the rate of its removal. talus forms rapidly in climates where mechanical disintegration is most effective, where rocks are readily broken into blocks because closely jointed and thinly bedded rather than massive, and where they are firm enough to be detached in fragments of some size instead of in fine grains. talus is removed slowly where it decays slowly, either because of the climate or the resistance of the rock. it may be rapidly removed by a stream flowing along its base. [illustration: fig. . talus at foot of granite cliffs, sierra nevada mountains] in a moist climate a soluble rock, such as massive limestone, may form talus little if any faster than the talus weathers away. a loose-textured sandstone breaks down into incoherent sand grains, which in dry climates, where unprotected by vegetation, may be blown away as fast as they fall, leaving the cliff bare to the base. cliffs of such slow-decaying rocks as quartzite and granite when closely jointed accumulate talus in large amounts. [illustration: fig. . diagram illustrating retreat of cliff, _c_, and talus, _t_] talus slopes may be so steep as to reach _the angle of repose_, i.e. the steepest angle at which the material will lie. this angle varies with different materials, being greater with coarse and angular fragments than with fine rounded grains. sooner or later a talus reaches that equilibrium where the amount removed from its surface just equals that supplied from the cliff above. as the talus is removed and weathers away its slope retreats together with the retreat of the cliff, as seen in figure . =graded slopes.= where rocks weather faster than their waste is carried away, the waste comes at last to cover all rocky ledges. on the steeper slopes it is coarser and in more rapid movement than on slopes more gentle, but mountain sides and hills and plains alike come to be mantled with sheets of waste which everywhere is creeping toward the streams. such unbroken slopes, worn or built to the least inclination at which the waste supplied by weathering can be urged onward, are known as _graded slopes_. of far less importance than the silent, gradual creep of waste, which is going on at all times everywhere about us, are the startling local and spasmodic movements which we are now to describe. =avalanches.= on steep mountain sides the accumulated snows of winter often slip and slide in avalanches to the valleys below. these rushing torrents of snow sweep their tracks clean of waste and are one of nature's normal methods of moving it along the downhill path. [illustration: fig. . a landslide, quebec] =landslides.= another common and abrupt method of delivering waste to streams is by slips of the waste mantle in large masses. after long rains and after winter frosts the cohesion between the waste and the sound rock beneath is loosened by seeping water underground. the waste slips on the rock surface thus lubricated and plunges down the mountain side in a swift roaring torrent of mud and stones. [illustration: fig. . diagram illustrating conditions favorable to a landslide _lm_, limestone dipping toward valley of river, _r_; _sh_, shale] we may conveniently mention here a second type of landslide, where masses of solid rock as well as the mantle of waste are involved in the sudden movement. such slips occur when valleys have been rapidly deepened by streams or glaciers and their sides have not yet been graded. a favorable condition is where the strata dip (i.e. incline downwards) towards the valley (fig. ), or are broken by joint planes dipping in the same direction. the upper layers, including perhaps the entire mountain side, have been cut across by the valley trench and are left supported only on the inclined surface of the underlying rocks. water may percolate underground along this surface and loosen the cohesion between the upper and the underlying strata by converting the upper surface of a shale to soft wet clay, by dissolving layers of a limestone, or by removing the cement of a sandstone and converting it into loose sand. when the inclined surface is thus lubricated the overlying masses may be launched into the valley below. the solid rocks are broken and crushed in sliding and converted into waste consisting, like that of talus, of angular unsorted fragments, blocks of all sizes being mingled pell-mell with rock meal and dust. the principal effects of landslides may be gathered from the following examples. at gohna, india, in , the face of a spur four thousand feet high, of the lower ranges of the himalayas, slipped into the gorge of the headwaters of the ganges river in successive rock falls which lasted for three days. blocks of stone were projected for a mile, and clouds of limestone dust were spread over the surrounding country. the débris formed a dam one thousand feet high, extending for two miles along the valley. a lake gathered behind this barrier, gradually rising until it overtopped it in a little less than a year. the upper portion of the dam then broke, and a terrific rush of water swept down the valley in a wave which, twenty miles away, rose one hundred and sixty feet in height. a narrow lake is still held by the strong base of the dam. in , after forty days of incessant rain, a cliff of sandstone slipped into the yangtse river in china, reducing the width of the channel to eighty yards and causing formidable rapids. [illustration: fig. . bowlders of weathering, granite quarry, cape ann, massachusetts] at flims, in switzerland, a prehistoric landslip flung a dam eighteen hundred feet high across the headwaters of the rhine. if spread evenly over a surface of twenty-eight square miles, the material would cover it to a depth of six hundred and sixty feet. the barrier is not yet entirely cut away, and several lakes are held in shallow basins on its hummocky surface. a slide from the precipitous river front of the citadel hill of quebec, in , dashed across champlain street, wrecking a number of houses and causing the death of forty-five persons. the strata here are composed of steeply dipping slate (fig. ). in lofty mountain ranges there may not be a single valley without its traces of landslides, so common there is this method of the movement of waste, and of building to grade over-steepened slopes. rock sculpture by weathering we are now to consider a few of the forms into which rock masses are carved by the weather. [illustration: fig. . differential weathering on a monument, colorado] =bowlders of weathering.= in many quarries and outcrops we may see that the blocks into which one or more of the uppermost layers have been broken along their joints and bedding planes are no longer angular, as are those of the layers below. the edges and corners of these blocks have been worn away by the weather. such rounded cores, known as bowlders of weathering, are often left to strew the surface. =differential weathering.= this term covers all cases in which a rock mass weathers differently in different portions. any weaker spots or layers are etched out on the surface, leaving the more resistant in relief. thus massive limestones become pitted where the weather drills out the weaker portions. in these pits, when once they are formed, moisture gathers, a little soil collects, vegetation takes root, and thus they are further enlarged until the limestone may be deeply honeycombed. [illustration: fig. . honeycombed limestone, iowa] [illustration: fig. . cliffs and slopes on north wall of the grand canyon of the colorado river, arizona] on the sides of canyons, and elsewhere where the edges of strata are exposed, the harder layers project as cliffs, while the softer weather back to slopes covered with the talus of the harder layers above them. it is convenient to call the former _cliff makers_ and the latter _slope makers_ (fig. ). differential weathering plays a large part in the sculpture of the land. areas of weak rock are wasted to plains, while areas of hard rock adjacent are still left as hills and mountain ridges, as in the valleys and mountains of eastern pennsylvania. but in such instances the lowering of the surface of the weaker rock is also due to the wear of streams, and especially to the removal by them from the land of the waste which covers and protects the rocks beneath. [illustration: fig. . taverlone mesa, new mexico] rocks owe their weakness to several different causes. some, such as beds of loose sand, are soft and easily worn by rains; some, as limestone and gypsum for example, are soluble. even hard insoluble rocks are weak under the attack of the weather when they are closely divided by joints and bedding planes and are thus readily broken up into blocks by mechanical agencies. [illustration: fig. . monuments, arizona note the rain furrows on the slope at the foot of the monuments. in the foreground are seen fragments of petrified trunks of trees, composed of silica and extremely resistant to the weather. on the removal of the rock layers in which these fragments were imbedded they are left to strew the surface in the same way as are the residual flints of southern missouri.] =outliers and monuments.= as cliffs retreat under the attack of the weather, portions are left behind where the rock is more resistant or where the attack for any reason is less severe. such remnant masses, if large, are known as outliers. when flat-topped, because of the protection of a resistant horizontal capping layer, they are termed _mesas_ (fig. ),--a term applied also to the flat-topped portions of dissected plateaus (fig. ). retreating cliffs may fall back a number of miles behind their outliers before the latter are finally consumed. [illustration: fig. . undercut monuments, colorado] monuments are smaller masses and may be but partially detached from the cliff face. in the breaking down of sheets of horizontal strata, outliers grow smaller and smaller and are reduced to massive rectangular monuments resembling castles (fig. ). the rock castle falls into ruin, leaving here and there an isolated tower; the tower crumbles to a lonely pillar, soon to be overthrown. the various and often picturesque shapes of monuments depend on the kind of rock, the attitude of the strata, and the agent by which they are chiefly carved. thus pillars may have a capital formed of a resistant stratum. monuments may be undercut and come to rest on narrow pedestals, wherever they weather more rapidly near the ground, either because of the greater moisture there, or--in arid climates--because worn at their base by drifting sands. stony clays disintegrating under the rain often contain bowlders which protect the softer material beneath from the vertical blows of raindrops, and thus come to stand on pedestals of some height (fig. ). one may sometimes see on the ground beneath dripping eaves pebbles left in the same way, protecting tiny pedestals of sand. =mountain peaks and ridges.= most mountains have been carved out of great broadly uplifted folds and blocks of the earth's crust. running water and glacier ice have cut these folds and blocks into masses divided by deep valleys; but it is by the weather, for the most part, that the masses thus separated have been sculptured to the present forms of the individual peaks and ridges. [illustration: fig. . roosevelt column, idaho an erosion pillar feet high. how was it produced? why quadrangular? what does it show as to the recent height of the hillside surface?] frost and heat and cold sculpture high mountains to sharp, tusklike peaks and ragged, serrate crests, where their waste is readily removed (fig. ). the matterhorn of the alps is a famous example of a mountain peak whose carving by the frost and other agents is in active progress. on its face "scarcely a rock anywhere is firmly attached," and the fall of loosened stones is incessant. mountain climbers who have camped at its base tell how huge rocks from time to time come leaping down its precipices, followed by trains of dislodged smaller fragments and rock dust; and how at night one may trace the course of the bowlders by the sparks which they strike from the mountain walls. mount assiniboine, canada (fig. ), resembles the matterhorn in form and has been carved by the same agencies. "the needles" of arizona are examples of sharp mountain peaks in a warm arid region sculptured chiefly by temperature changes. chemical decay, especially when carried on beneath a cover of waste and vegetation, favors the production of rounded knobs and dome-shaped mountains. =the weather curve.= we have seen that weathering reduces the angular block quarried by the frost to a rounded bowlder by chipping off its corners and smoothing away its edges. in much the same way weathering at last reduces to rounded hills the earth blocks cut by streams or formed in any other way. high mountains may at first be sculptured by the weather to savage peaks (fig. ), but toward the end of their life history they wear down to rounded hills (fig. ). the weather curve, which may be seen on the summits of low hills (fig. ), is convex upward. [illustration: fig. . mount assiniboine, canada] [illustration: fig. . big round top and little round top, gettysburg, pennsylvania] in figure , representing a cubic block of stone whose faces are a yard square, how many square feet of surface are exposed to the weather by a cubic foot at a corner _a_; by one situated in the middle of an edge _b_; by one in the center of a side _c_? how much faster will _a_ and _b_ weather than _c_, and what will be the effect on the shape of the block? [illustration: fig. ] =the coöperation of various agencies in rock sculpture.= for the sake of clearness it is necessary to describe the work of each geological agent separately. we must not forget, however, that in nature no agent works independently and alone; that every result is the outcome of a long chain of causes. thus, in order that the mountain peak may be carved by the agents of disintegration, the waste must be rapidly removed,--a work done by many agents, including some which we are yet to study; and in order that the waste may be removed as fast as formed, the region must first have been raised well above the level of the sea, so that the agents of transportation could do their work effectively. the sculpture of the rocks is accomplished only by the coöperation of many forces. the constant removal of waste from the surface by creep and wash and carriage by streams is of the highest importance, because it allows the destruction of the land by means of weathering to go on as long as any land remains above sea level. if waste were not removed, it would grow to be so thick as to protect the rock beneath from further weathering, and the processes of destruction which we have studied would be brought to an end. the very presence of the mantle of waste over the land proves that on the whole rocks weather more rapidly than their waste is removed. the destruction of the land is going on as fast as the waste can be carried away. we have now learned to see in the mantle of waste the record of the destructive action of the agencies of weathering on the rocks of the land surface. similar records we shall find buried deeply among the rocks of the crust in old soils and in rocks pitted and decayed, telling of old land surfaces long wasted by the weather. ever since the dry land appeared these agencies have been as now quietly and unceasingly at work upon it, and have ever been the chief means of the destruction of its rocks. the vast bulk of the stratified rocks of the earth's crust is made up almost wholly of the waste thus worn from ancient lands. [illustration: fig. . mount sneffels, colorado describe and account for what you see in this view. what changes may the mountain be expected to undergo in the future from the agencies now at work upon it?] in studying the various geological agencies we must remember the almost inconceivable times in which they work. the slowest process when multiplied by the immense time in which it is carried on produces great results. the geologist looks upon the land forms of the earth's surface as monuments which record the slow action of weathering and other agents during the ages of the past. the mountain peak, the rounded hill, the wide plain which lies where hills and mountains once stood, tell clearly of the great results which slow processes will reach when given long time in which to do their work. we should accustom ourselves also to think of the results which weathering will sooner or later bring to pass. the tombstone and the bowlder of the field, which each year lose from their surfaces a few crystalline grains, must in time be wholly destroyed. the hill whose rocks are slowly rotting underneath a cover of waste must become lower and lower as the centuries and millenniums come and go, and will finally disappear. even the mountains are crumbling away continually, and therefore are but fleeting features of the landscape. chapter ii the work of ground water =land waters.= we have seen how large is the part that water plays at and near the surface of the land in the processes of weathering and in the slow movement of waste down all slopes to the stream ways. we now take up the work of water as it descends beneath the ground,--a corrosive agent still, and carrying in solution as its load the invisible waste of rocks derived from their soluble parts. land waters have their immediate source in the rainfall. by the heat of the sun water is evaporated from the reservoir of the ocean and from moist surfaces everywhere. mingled as vapor with the air, it is carried by the winds over sea and land, and condensed it returns to the earth as rain or snow. that part of the rainfall which descends on the ocean does not concern us, but that which falls on the land accomplishes, as it returns to the sea, the most important work of all surface geological agencies. the rainfall may be divided into three parts: the first _dries up_, being discharged into the air by evaporation either directly from the soil or through vegetation; the second _runs off_ over the surface to flood the streams; the third _soaks in_ the ground and is henceforth known as _ground_ or _underground water_. =the descent of ground water.= seeping through the mantle of waste, ground water soaks into the pores and crevices of the underlying rock. all rocks of the upper crust of the earth are more or less porous, and all drink in water. _impervious rocks_, such as granite, clay, and shale, have pores so minute that the water which they take in is held fast within them by capillary attraction, and none drains through. _pervious rocks_, on the other hand, such as many sandstones, have pore spaces so large that water filters through them more or less freely. besides its seepage through the pores of pervious rocks, water passes to lower levels through the joints and cracks by which all rocks, near the surface are broken. even the closest-grained granite has a pore space of in , while sandstone may have a pore space of in . sand is so porous that it may absorb a third of its volume of water, and a loose loam even as much as one half. [illustration: fig. . diagram illustrating the relation of the ground-water surface to the surface of the ground the dotted line represents the ground-water surface, and the arrows indicate the direction of the movements of ground-water. _m_, marsh; _w_, well; _r_, river] =the ground-water surface= is the name given the upper surface of ground water, the level below which all rocks are saturated. in dry seasons the ground-water surface sinks. for ground water is constantly seeping downward under gravity, it is evaporated in the waste and its moisture is carried upward by capillarity and the roots of plants to the surface to be evaporated in the air. in wet seasons these constant losses are more than made good by fresh supplies from that part of the rainfall which soaks into the ground, and the ground-water surface rises. in moist climates the ground-water surface (fig. ) lies, as a rule, within a few feet of the land surface and conforms to it in a general way, although with slopes of less inclination than those of the hills and valleys. in dry climates permanent ground water may be found only at depths of hundreds of feet. ground water is held at its height by the fact that its circulation is constantly impeded by capillarity and friction. if it were as free to drain away as are surface streams, it would sink soon after a rain to the level of the deepest valleys of the region. =wells and springs.= excavations made in permeable rocks below the ground-water surface fill to its level and are known as wells. where valleys cut this surface permanent streams are formed, the water either oozing forth along ill-defined areas or issuing at definite points called springs, where it is concentrated by the structure of the rocks. a level tract where the ground-water surface coincides with the surface of the ground is a swamp or marsh. by studying a spring one may learn much of the ways and work of ground water. spring water differs from that of the stream into which it flows in several respects. if we test the spring with a thermometer during successive months, we shall find that its temperature remains much the same the year round. in summer it is markedly cooler than the stream; in winter it is warmer and remains unfrozen while the latter perhaps is locked in ice. this means that its underground path must lie at such a distance from the surface that it is little affected by summer's heat and winter's cold. while the stream is often turbid with surface waste washed into it by rains, the spring remains clear; its water has been filtered during its slow movement through many small underground passages and the pores of rocks. commonly the spring differs from the stream in that it carries a far larger load of dissolved rock. chemical analysis proves that streams contain various minerals in solution, but these are usually in quantities so small that they are not perceptible to the taste or feel. but the water of springs is often well charged with soluble minerals; in its slow, long journey underground it has searched out the soluble parts of the rocks through which it seeps and has dissolved as much of them as it could. when spring water is boiled away, the invisible load which it has carried is left behind, and in composition is found to be practically identical with that of the soluble ingredients of the country rock. although to some extent the soluble waste of rocks is washed down surface slopes by the rain, by far the larger part is carried downward by ground water and is delivered to streams by springs. in limestone regions springs are charged with calcium carbonate (the carbonate of lime), and where the limestone is magnesian they contain magnesium carbonate also. such waters are "hard"; when used in washing, the minerals which they contain combine with the fatty acids of soap to form insoluble curdy compounds. when springs rise from rocks containing gypsum they are hard with calcium sulphate. in granite regions they contain more or less soda and potash from the decay of feldspar. the flow of springs varies much less during the different seasons of the year than does that of surface streams. so slow is the movement of ground water through the rocks that even during long droughts large amounts remain stored above the levels of surface drainage. =movements of ground water.= ground water is in constant movement toward its outlets. its rate varies according to many conditions, but always is extremely slow. even through loose sands beneath the beds of rivers it sometimes does not exceed a fifth of a mile a year. [illustration: fig. . geological conditions favorable to strong springs _a_, limestone; _b_, shale; _c_, coarse sandstone; _d_, limestone; _e_, sandstone; _f_, fissure. the strata dip toward the south, _s_. redraw the diagram, marking the points at which strong springs (_ss_) may be expected.] in any region two zones of flow may be distinguished. the _upper zone of flow_ extends from the ground-water surface downward through the waste mantle and any permeable rocks on which the mantle rests, as far as the first impermeable layer, where the descending movement of the water is stopped. the =deep zones of flow= occupy any pervious rocks which may be found below the impervious layer which lies nearest to the surface. the upper zone is a vast sheet of water saturating the soil and rocks and slowly seeping downward through their pores and interstices along the slopes to the valleys, where in part it discharges in springs and often unites also in a wide underflowing stream which supports and feeds the river (fig. ). [illustration: fig. . diagram of well which goes dry in drought, _a_, and of of unfailing well, _b_ redraw the diagram, showing by dotted line the normal ground-water surface and by broken line the ground-water surface at times of drought] [illustration: fig. . diagram of wet weather stream, _a_, and of permanent stream, _b_ redraw the diagram, showing ground-water surface by dotted line] a city in a region of copious rains, built on the narrow flood plain of a river, overlooked by hills, depends for its water supply on driven wells, within the city limits, sunk in the sand a few yards from the edge of the stream. are these wells fed by water from the river percolating through the sand, or by ground water on its way to the stream and possibly contaminated with the sewage of the town? at what height does underground water stand in the wells of your region? does it vary with the season? have you ever known wells to go dry? it may be possible to get data from different wells and to draw a diagram showing the ground-water surface as compared with the surface of the ground. =fissure springs and artesian wells.= the _deeper zones of flow_ lie in pervious strata which are overlain by some impervious stratum. such layers are often carried by their dip to great depths, and water may circulate in them to far below the level of the surface streams and even of the sea. when a fissure crosses a water-bearing stratum, or _aquifer, water is forced upward by the pressure of the weight of the water contained in the higher parts of the stratum, and may reach the surface as a fissure spring. a boring which taps such an aquifer is known as an artesian well, a name derived from a province in france where wells of this kind have been long in use. the rise of the water in artesian wells, and in fissure springs also, depends on the following conditions illustrated in figure . the aquifer dips toward the region of the wells from higher ground, where it outcrops and receives its water. it is inclosed between an impervious layer above and water-tight or water-logged layers beneath. the weight of the column of water thus inclosed in the aquifer causes water to rise in the well, precisely as the weight of the water in a standpipe forces it in connected pipes to the upper stories of buildings. [illustration: fig. . section across south dakota from the black hills to sioux falls (s), illustrating the conditions of artesian wells _a_, crystalline impervious rocks; _b_, sedimentary rocks, shales, limestones, and sandstones; _c_, pervious sandstone, the aquifer; _d_, impervious shales; _w_, _w_, _w_, artesian wells.] which will supply the larger region with artesian wells, an aquifer whose dip is steep or one whose dip is gentle? which of the two aquifers, their thickness being equal, will have the larger outcrop and therefore be able to draw upon the larger amount of water from the rainfall? illustrate with diagrams. =the zone of solution.= near the surface, where the circulation of ground water is most active, it oxidizes, corrodes, and dissolves the rocks through which it passes. it leaches soils and subsoils of their lime and other soluble minerals upon which plants depend for their food. it takes away the soluble cements of rocks; it widens fissures and joints and opens winding passages along the bedding planes; it may even remove whole beds of soluble rocks, such as rock salt, limestone, or gypsum. the work of ground water in producing landslides has already been noticed. the zone in which the work of ground water is thus for the most part destructive we may call the zone of solution. [illustration: fig. . diagram of caverns and sink holes] =caves.= in massive limestone rocks, ground water dissolves channels which sometimes form large caves (fig. ). the necessary conditions for the excavation of caves of great size are well shown in central kentucky, where an upland is built throughout of thick horizontal beds of limestone. the absence of layers of insoluble or impervious rock in its structure allows a free circulation of ground water within it by the way of all natural openings in the rock. these water ways have been gradually enlarged by solution and wear until the upland is honeycombed with caves. five hundred open caverns are known in one county. mammoth cave, the largest of these caverns, consists of a labyrinth of chambers and winding galleries whose total length is said to be as much as thirty miles. one passage four miles long has an average width of about sixty feet and an average height of forty feet. one of the great halls is three hundred feet in width and is overhung by a solid arch of limestone one hundred feet above the floor. galleries at different levels are connected by well-like pits, some of which measure two hundred and twenty-five feet from top to bottom. through some of the lowest of these tunnels flows echo river, still at work dissolving and wearing away the rock while on its dark way to appear at the surface as a great spring. =natural bridges.= as a cavern enlarges and the surface of the land above it is lowered by weathering, the roof at last breaks down and the cave becomes an open ravine. a portion of the roof may for a while remain, forming a "natural bridge." =sink holes.= in limestone regions channels under ground may become so well developed that the water of rains rapidly drains away through them. ground water stands low and wells must be sunk deep to find it. little or no surface water is left to form brooks. [illustration: fig. . sink holes in the karst, austria] thus across the limestone upland of central kentucky one meets but three surface streams in a hundred miles. between their valleys surface water finds its way underground by means of sink holes. these are pits, commonly funnel shaped, formed by the enlargement of crevice or joint by percolating water, or by the breakdown of some portion of the roof of a cave. by clogging of the outlet a sink hole may come to be filled by a pond. central florida is a limestone region with its drainage largely subterranean and in part below the level even of the sea. sink holes are common, and many of them are occupied by lakelets. great springs mark the point of issue of underground streams, while some rise from beneath the sea. silver spring, one of the largest, discharges from a basin eight hundred feet wide and thirty feet deep a little river navigable for small steamers to its source. about the spring there are no surface streams for sixty miles. [illustration: fig. . underground stream issuing from base of cliff, the karst, austria] =the karst.= along the eastern coast of the adriatic, as far south as montenegro, lies a belt of limestone mountains singularly worn and honeycombed by the solvent action of water. where forests have been cut from the mountain sides and the red soil has washed away, the surface of the white limestone forms a pathless desert of rock where each square rod has been corroded into an intricate branch work of shallow furrows and sharp ridges. great sink holes, some of them six hundred feet deep and more, pockmark the surface of the land. the drainage is chiefly subterranean. surface streams are rare and a portion of their courses is often under ground. fragmentary valleys come suddenly to an end at walls of rock where the rivers which occupy the valleys plunge into dark tunnels to reappear some miles away. ground water stands so far below the surface that it cannot be reached by wells, and the inhabitants depend on rain water stored for household uses. the finest cavern of europe, the adelsberg grotto, is in this region. karst, the name of a part of this country, is now used to designate any region or landscape thus sculptured by the chemical action of surface and ground water. we must remember that karst regions are rare, and striking as is the work of their subterranean streams, it is far less important than the work done by the sheets of underground water slowly seeping through all subsoils and porous rocks in other regions. even when gathered into definite channels, ground water does not have the erosive power of surface streams, since it carries with it little or no rock waste. regions whose underground drainage is so perfect that the development of surface streams has been retarded or prevented escape to a large extent the leveling action of surface running waters, and may therefore stand higher than the surrounding country. the hill honeycombed by luray cavern, virginia, has been attributed to this cause. [illustration: fig. . stalactites and stalagmites, marengo cavern, indiana] =cavern deposits.= even in the zone of solution water may under certain circumstances deposit as well as erode. as it trickles from the roof of caverns, the lime carbonate which it has taken into solution from the layers of limestone above is deposited by evaporation in the air in icicle-like pendants called _stalactites_. as the drops splash on the floor there are built up in the same way thicker masses called _stalagmites_, which may grow to join the stalactites above, forming pillars. a stalagmitic crust often seals with rock the earth which accumulates in caverns, together with whatever relics of cave dwellers, either animals or men, it may contain. can you explain why slender stalactites formed by the drip of single drops are often hollow pipes? =the zone of cementation.= with increasing depth subterranean water becomes more and more sluggish in its movements and more and more highly charged with minerals dissolved from the rocks above. at such depths it deposits these minerals in the pores of rocks, cementing their grains together, and in crevices and fissures, forming mineral veins. thus below the zone of solution where the work of water is to dissolve, lies the zone of cementation where its work is chemical deposit. a part of the invisible load of waste is thus transferred from rocks near the surface to those at greater depths. as the land surface is gradually lowered by weathering and the work of rain and streams, rocks which have lain deep within the zone of cementation are brought within the zone of solution. thus there are exposed to view limestones, whose cracks were filled with calcite (crystallized carbonate of lime), with quartz or other minerals, and sandstones whose grains were well cemented many feet below the surface. =cavity filling.= small cavities in the rocks are often found more or less completely filled with minerals deposited from solution by water in its constant circulation underground. the process may be illustrated by the deposit of salt crystals in a cup of evaporating brine, but in the latter instance the solution is not renewed as in the case of cavities in the rocks. a cavity thus lined with inward-pointing crystals is called a _geode_. =concretions.= ground water seeping through the pores of rocks may gather minerals disseminated throughout them into nodular masses called concretions. thus silica disseminated through limestone is gathered into nodules of flint. while geodes grow from the outside inwards, concretions grow outwards from the center. nor are they formed in already existing cavities as are geodes. in soft clays concretions may, as they grow, press the clay aside. in many other rocks concretions are made by the process of _replacement_. molecule by molecule the rock is removed and the mineral of the concretion substituted in its place. the concretion may in this way preserve intact the lamination lines or other structures of the rock (fig. ). clays and shales often contain concretions of lime carbonate, of iron carbonate, or of iron sulphide. some fossil, such as a leaf or shell, frequently forms the nucleus around which the concretion grows. why are building stones more easily worked when "green" than after their quarry water has dried out? [illustration: fig. . concretions in sandstone, wyoming] =deposits of ground water in arid regions.= in arid lands where ground water is drawn by capillarity to the surface and there evaporates, it leaves as surface incrustations the minerals held in solution. white limy incrustations of this nature cover considerable tracts in northern mexico. evaporating beneath the surface, ground water may deposit a limy cement in beds of loose sand and gravel. such firmly cemented layers are not uncommon in western kansas and nebraska, where they are known as "mortar beds." =thermal springs.= while the lower limit of surface drainage is sea level, subterranean water circulates much below that depth, and is brought again to the surface by hydrostatic pressure. in many instances springs have a higher temperature than the average annual temperature of the region, and are then known as thermal springs. in regions of present or recent volcanic activity, such as the yellowstone national park, we may believe that the heat of thermal springs is derived from uncooled lavas, perhaps not far below the surface. but when hot springs occur at a distance of hundreds of miles from any volcano, as in the case of the hot springs of bath, england, it is probable that their waters have risen from the heated rocks of the earth's interior. the springs of bath have a temperature of ° f., ° above the average annual temperature of the place. if we assume that the rate of increase in the earth's internal heat is here the average rate, ° f. to every sixty feet of descent, we may conclude that the springs of bath rise from at least a depth of forty-two hundred feet. water may descend to depths from which it can never be brought back by hydrostatic pressure. it is absorbed by highly heated rocks deep below the surface. from time to time some of this deep-seated water may be returned to open air in the steam of volcanic eruptions. [illustration: fig. . calcareous deposits from hot springs, yellowstone national park] =surface deposits of springs.= where subterranean water returns to the surface highly charged with minerals in solution, on exposure to the air it is commonly compelled to lay down much of its invisible load in chemical deposits about the spring. these are thrown down from solution either because of cooling, evaporation, the loss of carbon dioxide, or the work of algae. many springs have been charged under pressure with carbon dioxide from subterranean sources and are able therefore to take up large quantities of lime carbonate from the limestone rocks through which they pass. on reaching the surface the pressure is relieved, the gas escapes, and the lime carbonate is thrown down in deposits called _travertine_. the gas is sometimes withdrawn and the deposit produced in large part by the action of algae and other humble forms of plant life. at the mammoth hot springs in the valley of the gardiner river, yellowstone national park, beautiful terraces and basins of travertine (fig. ) are now building, chiefly by means of algae which cover the bottoms, rims, and sides of the basins and deposit lime carbonate upon them in successive sheets. the rock, snow-white where dry, is coated with red and orange gelatinous mats where the algae thrive in the over-flowing waters. similar terraces of travertine are found to a height of fourteen hundred feet up the valley side. we may infer that the springs which formed these ancient deposits discharged near what was then the bottom of the valley, and that as the valley has been deepened by the river the ground water of the region has found lower and lower points of issue. in many parts of the country calcareous springs occur which coat with lime carbonate mosses, twigs, and other objects over which their waters flow. such are popularly known as petrifying springs, although they merely incrust the objects and do not convert them into stone. silica is soluble in alkaline waters, especially when these are hot. hot springs rising through alkaline siliceous rocks, such as lavas, often deposit silica in a white spongy formation known as _siliceous sinter_, both by evaporation and by the action of algae which secrete silica from the waters. it is in this way that the cones and mounds of the geysers in the yellowstone national park and in iceland have been formed (fig. ). where water oozes from the earth one may sometimes see a rusty deposit on the ground, and perhaps an iridescent scum upon the water. the scum is often mistaken for oil, but at a touch it cracks and breaks, as oil would not do. it is a film of hydrated iron oxide, or _limonite_, and the spring is an iron, or chalybeate, spring. compounds of iron have been taken into solution by ground water from soil and rocks, and are now changed to the insoluble oxide on exposure to the oxygen of the air. in wet ground iron compounds leached by ground water from the soil often collect in reddish deposits a few feet below the surface, where their downward progress is arrested by some impervious clay. at the bottom of bogs and shallow lakes iron ores sometimes accumulate to a depth of several feet. decaying organic matter plays a large part in these changes. in its presence the insoluble iron oxides which give color to most red and yellow rocks are decomposed, leaving the rocks of a gray or bluish color, and the soluble iron compounds which result are readily leached out,--effects seen where red or yellow clays have been bleached about some decaying tree root. the iron thus dissolved is laid down as limonite when oxidized, as about a chalybeate spring; but out of contact with the air and in the presence of carbon dioxide supplied by decaying vegetation, as in a peat bog, it may be deposited as iron carbonate, or _siderite_. =total amount of underground waters.= in order to realize the vast work in solution and cementation which underground waters are now doing and have done in all geological ages, we must gain some conception of their amount. at a certain depth, estimated at about six miles, the weight of the crust becomes greater than the rocks can bear, and all cavities and pores in them must be completely closed by the enormous pressure which they sustain. below a depth, therefore, water cannot go. above it all rocks are water-soaked, up to the limit of their capacity, to within a few feet of the surface. estimating the average pore space of the rocks above a depth of six miles at from two and a half per cent to five per cent of their volume, it is found that the total amount of ground water may be great enough to cover the entire surface of the earth to a depth of from eight hundred to sixteen hundred feet. chapter iii rivers and valleys =the run-off.= we have traced the history of that portion of the rainfall which soaks into the ground; let us now return to that part which washes along the surface and is known as the _run-off_. fed by rains and melting snows, the run-off gathers into courses, perhaps but faintly marked at first, which join more definite and deeply cut channels, as twigs their stems. in a humid climate the larger ravines through which the run-off flows soon descend below the ground-water surface. here springs discharge along the sides of the little valleys and permanent streams begin. the water supplied by the run-off here joins that part of the rainfall which had soaked into the soil, and both now proceed together by way of the stream to the sea. =river floods.= streams vary greatly in volume during the year. at stages of flood they fill their immediate banks, or overrun them and inundate any low lands adjacent to the channel; at stages of low water they diminish to but a fraction of their volume when at flood. at times of flood, rivers are fed chiefly by the run-off; at times of low water, largely or even wholly by springs. how, then, will the water of streams differ at these times in turbidity and in the relative amount of solids carried in solution? in parts of england streams have been known to continue flowing after eighteen months of local drought, so great is the volume of water which in humid climates is stored in the rocks above the drainage level, and so slowly is it given off in springs. in illinois and the states adjacent, rivers remain low in winter and a "spring freshet" follows the melting of the winter's snows. a "june rise" is produced by the heavy rains of early summer. low water follows in july and august, and streams are again swollen to a moderate degree under the rains of autumn. =the discharge of streams.= the per cent of rainfall discharged by rivers varies with the amount of rainfall, the slope of the drainage area, the texture of the rocks, and other factors. with an annual rainfall of fifty inches in an open country, about fifty per cent is discharged; while with a rainfall of twenty inches only fifteen per cent is discharged, part of the remainder being evaporated and part passing underground beyond the drainage area. thus the ohio discharges thirty per cent of the rainfall of its basin, while the missouri carries away but fifteen per cent. a number of the streams of the semi-arid lands of the west do not discharge more than five per cent of the rainfall. other things being equal, which will afford the larger proportion of run-off, a region underlain with granite rock or with coarse sandstone? grass land or forest? steep slopes or level land? a well-drained region or one abounding in marshes and ponds? frozen or unfrozen ground? will there be a larger proportion of run-off after long rains or after a season of drought? after long and gentle rains, or after the same amount of precipitation in a violent rain? during the months of growing vegetation, from june to august, or during the autumn months? [illustration: fig. . rise of ground-water surface (broken line) beneath valley (_v_) in arid region] =desert streams.= in arid regions the ground-water surface lies so low that for the most part stream ways do not intersect it. streams therefore are not fed by springs, but instead lose volume as their waters soak into the thirsty rocks over which they flow. they contribute to the ground water of the region instead of being increased by it. being supplied chiefly by the run-off, they wither at times of drought to a mere trickle of water, to a chain of pools, or go wholly dry, while at long intervals rains fill their dusty beds with sudden raging torrents. desert rivers therefore periodically shorten and lengthen their courses, withering back at times of drought for scores of miles, or even for a hundred miles from the point reached by their waters during seasons of rain. =the geological work of streams.= the work of streams is of three kinds,--transportation, erosion, and deposition. streams _transport_ the waste of the land; they wear, or _erode_, their channels both on bed and banks; and they _deposit_ portions of their load from time to time along their courses, finally laying it down in the sea. most of the work of streams is done at times of flood. transportation =the invisible load of streams.= of the waste which a river transports we may consider first the invisible load which it carries in solution, supplied chiefly by springs but also in part by the run-off and from the solution of the rocks of its bed. more than half the dissolved solids in the water of the average river consists of the carbonates of lime and magnesia; other substances are gypsum, sodium sulphate (glauber's salts), magnesium sulphate (epsom salts), sodium chloride (common salt), and even silica, the least soluble of the common rock-making minerals. the amount of this invisible load is surprisingly large. the mississippi, for example, transports each year , , tons of dissolved rock to the gulf. =the visible load of streams.= this consists of the silt which the stream carries in suspension, and the sand and gravel and larger stones which it pushes along its bed. especially in times of flood one may note the muddy water, its silt being kept from settling by the rolling, eddying currents; and often by placing his ear close to the bottom of a boat one may hear the clatter of pebbles as they are hurried along. in mountain torrents the rumble of bowlders as they clash together may be heard some distance away. the amount of the load which a stream can transport depends on its velocity. a current of two thirds of a mile per hour can move fine sand, while one of four miles per hour sweeps along pebbles as large as hen's eggs. the transporting power of a stream varies as the sixth power of its velocity. if its velocity is multiplied by two, its transporting power is multiplied by the sixth power of two: it can now move stones sixty-four times as large as it could before. stones weigh from two to three times as much as water, and in water lose the weight of the volume of water which they displace. what proportion, then, of their weight in air do stones lose when submerged? =measurement of stream loads.= to obtain the total amount of waste transported by a river is an important but difficult matter. the amount of water discharged must first be found by multiplying the number of square feet in the average cross section of the stream by its velocity per second, giving the discharge per second in cubic feet. the amount of silt to a cubic foot of water is found by filtering samples of the water taken from different parts of the stream and at different times in the year, and drying and weighing the residues. the average amount of silt to the cubic foot of water, multiplied by the number of cubic feet of water discharged per year, gives the total load carried in suspension during that time. adding to this the estimated amount of sand and gravel rolled along the bed, which in many swift rivers greatly exceeds the lighter material held in suspension, and adding also the total amount of dissolved solids, we reach the exceedingly important result of the total load of waste discharged by the river. dividing the volume of this load by the area of the river basin gives another result of the greatest geological interest,--the rate at which the region is being lowered by the combined action of weathering and erosion, or the rate of denudation. =the rate of denudation of river basins.= this rate varies widely. the mississippi basin may be taken as a representative land surface because of the varieties of surface, altitude and slope, climate, and underlying rocks which are included in its great extent. careful measurements show that the mississippi basin is now being lowered at a rate of one four-thousandth of a foot a year, or one foot in four thousand years. taking this as the average rate of denudation for the land surfaces of the globe, estimates have been made of the length of time required at this rate to wash and wear the continents to the level of the sea. as the average elevation of the lands of the globe is reckoned at feet, this result would occur in nine or ten million years, if the present rate of denudation should remain unchanged. but even if no movements of the earth's crust should lift or depress the continents, the rate of wear and the removal of waste from their surfaces will not remain the same. it must constantly decrease as the lands are worn nearer to sea level and their slopes become more gentle. the length of time required to wear them away is therefore far in excess of that just stated. the drainage area of the potomac is , square miles. the silt brought down in suspension in a year would cover a square mile to the depth of four feet. at what rate is the potomac basin being lowered from this cause alone? it is estimated that the upper ganges is lowering its basin at the rate of one foot in years, and the po one foot in years. why so much faster than the potomac and the mississippi? =how streams get their loads.= the load of streams is derived from a number of sources, the larger part being supplied by the weathering of valley slopes. we have noticed how the mantle of waste creeps and washes to the stream ways. watching the run-off during a rain, as it hurries muddy with waste along the gutter or washes down the hillside, we may see the beginning of the route by which the larger part of their load is delivered to rivers. streams also secure some of their load by wearing it from their beds and banks,--a process called erosion. erosion streams erode their beds chiefly by means of their bottom load,--the stones of various sizes and the sand and even the fine mud which they sweep along. with these tools they smooth, grind, and rasp the rock of their beds, using them in much the fashion of sandpaper or a file. [illustration: fig. . pothole in bed of stream, ireland] =weathering of river beds.= the erosion of stream beds is greatly helped by the work of the weather. especially at low water more or less of the bed is exposed to the action of frost and heat and cold, joints are opened, rocks are pried loose and broken up and made ready to be swept away by the stream at time of flood. =potholes.= in rapids streams also drill out their rocky beds. where some slight depression gives rise to an eddy, the pebbles which gather in it are whirled round and round, and, acting like the bit of an auger, bore out a cylindrical pit called a pothole. potholes sometimes reach a depth of a score of feet. where they are numerous they aid materially in deepening the channel, as the walls between them are worn away and they coalesce. =waterfalls.= one of the most effective means of erosion which the river possesses is the waterfall. the plunging water dislodges stones from the face of the ledge over which it pours, and often undermines it by excavating a deep pit at its base. slice after slice is thus thrown down from the front of the cliff, and the cataract cuts its way upstream leaving a gorge behind it. [illustration: fig. . map of the gorge of the niagara river] =niagara falls.= the niagara river flows from lake erie at buffalo in a broad channel which it has cut but a few feet below the level of the region. some thirteen miles from the outlet it plunges over a ledge one hundred and seventy feet high into the head of a narrow gorge which extends for seven miles to the escarpment of the upland in which the gorge is cut. the strata which compose the upland dip gently upstream and consist at top of a massive limestone, at the falls about eighty feet thick, and below of soft and easily weathered shale. beneath the falls the underlying shale is cut and washed away by the descending water and retreats also because of weathering, while the overhanging limestone breaks down in huge blocks from time to time. niagara is divided by goat island into the horseshoe falls and the american falls. the former is supplied by the main current of the river, and from the semicircular sweep of its rim a sheet of water in places at least fifteen or twenty feet deep plunges into a pool a little less than two hundred feet in depth. here the force of the falling water is sufficient to move about the fallen blocks of limestone and use them in the excavation of the shale of the bed. at the american falls the lesser branch of the river, which flows along the american side of goat island, pours over the side of the gorge and breaks upon a high talus of limestone blocks which its smaller volume of water is unable to grind to pieces and remove. a series of surveys have determined that from to the horseshoe falls retreated at the rate of . feet per year, while the american falls retreated at the rate of . feet in the same period. we cannot doubt that the same agency which is now lengthening the gorge at this rapid rate has cut it back its entire length of seven miles. while niagara falls have been cutting back a gorge seven miles long and from two hundred to three hundred feet deep, the river above the falls has eroded its bed scarcely below the level of the upland on which it flows. like all streams which are the outlets of lakes, the niagara flows out of lake erie clear of sediment, as from a settling basin, and carries no tools with which to abrade its bed. we may infer from this instance how slight is the erosive power of clear water on hard rock. [illustration: fig. . longitudinal section of niagara gorge black, water; _f_, falls; _r_, rapids; _w_, whirlpool; _e_, escarpment; _n_, north; _s_, south] assuming that the rate of recession of the combined volumes of the american and horseshoe falls was three feet a year below goat island, and _assuming that this rate has been uniform in the past_, how long is it since the niagara river fell over the edge of the escarpment where now is the mouth of the present gorge? the profile of the bed of the niagara along the gorge (fig. ) shows alternating deeps and shallows which cannot be accounted for, except in a single instance, by the relative hardness of the rocks of the river bed. the deeps do not exceed that at the foot of the horseshoe falls at the present time. when the gorge was being cut along the shallows, how did the falls compare in excavating power, in force, and volume with the niagara of to-day? how did the rate of recession at those times compare with the present rate? is the assumption made above that the rate of recession has been uniform correct? the first stretch of shallows below the falls causes a tumultuous rapid impossible to sound. its depth has been estimated at thirty-five feet. from what data could such an estimate be made? suggest a reason why the horseshoe falls are convex upstream. at the present rate of recession which will reach the head of goat island the sooner, the american or the horseshoe falls? what will be the fate of the falls left behind when the other has passed beyond the head of the island? the rate at which a stream erodes its bed depends in part upon the nature of the rocks over which it flows. will a stream deepen its channel more rapidly on massive or on thin-bedded and close-jointed rocks? on horizontal strata or on strata steeply inclined? [illustration: fig. . a stream in scotland in what ways is the bed now being deepened?] deposition while the river carries its invisible load of dissolved rock on without stop to the sea, its load of visible waste is subject to many delays en route. now and again it is laid aside, to be picked up later and carried some distance farther on its way. one of the most striking features of the river therefore is the waste accumulated along its course, in bars and islands in the channel, beneath its bed, and in flood plains along its banks. all this _alluvium_, to use a general term for river deposits, with which the valley is cumbered is really en route to the sea; it is only temporarily laid aside to resume its journey later on. constantly the river is destroying and rebuilding its alluvial deposits, here cutting and there depositing along its banks, here eroding and there building a bar, here excavating its bed and there filling it up, and at all times carrying the material picked up at one point some distance on downstream before depositing it at another. [illustration: fig. . sand bar deposited by stream, showing cross bedding] these deposits are laid down by slackening currents where the velocity of the stream is checked, as on the inner side of curves, and where the slope of the bed is diminished, and in the lee of islands, bridge piers and projecting points of land. how slight is the check required to cause a current to drop a large part of its load may be inferred from the law of the relation of the transporting power to the velocity. if the velocity is decreased one half, the current can move fragments but one sixty-fourth the size of those which it could move before, and must drop all those of larger size. will a river deposit more at low water or at flood? when rising or when falling? =stratification.= river deposits are stratified, as may be seen in any fresh cut in banks or bars. the waste of which they are built has been sorted and deposited in layers, one above another; some of finer and some of coarser material. the sorting action of running water depends on the fact that its transporting power varies with the velocity. a current whose diminishing velocity compels it to drop coarse gravel, for example, is still able to move all the finer waste of its load, and separating it from the gravel, carries it on downstream; while at a later time slower currents may deposit on the gravel bed layers of sand, and, still later, slack water may leave on these a layer of mud. in case of materials lighter than water the transporting power does not depend on the velocity, and logs of wood, for instance, are floated on to the sea on the slowest as well as on the most rapid currents. [illustration: fig. . longitudinal section of a river bar] =cross bedding.= a section of a bar exposed at low water may show that it is formed of layers of sand, or coarser stuff, inclined downstream as steeply often as the angle of repose of the material. from a boat anchored over the lower end of a submerged sand bar we may observe the way in which this structure, called cross bedding, is produced. sand is continually pushed over the edge of the bar at _b_ (fig. ) and comes to rest in successive layers on the sloping surface. at the same time the bar may be worn away at the upper end, _a_, and thus slowly advance down stream. while the deposit is thus cross bedded, it constitutes as a whole a stratum whose upper and lower surfaces are about horizontal. in sections of river banks one may often see a vertical succession of cross-bedded strata, each built in the way described. =water wear.= the coarser material of river deposits, such as cobblestones, gravel, and the larger grains of sand, are _water worn_, or rounded, except when near their source. rolling along the bottom they have been worn round by impact and friction as they rubbed against one another and the rocky bed of the stream. experiments have shown that angular fragments of granite lose nearly half their weight and become well rounded after traveling fifteen miles in rotating cylinders partly filled with water. marbles are cheaply made in germany out of small limestone cubes set revolving in a current of water between a rotating bed of stone and a block of oak, the process requiring but about fifteen minutes. it has been found that in the upper reaches of mountain streams a descent of less than a mile is sufficient to round pebbles of granite. [illustration: fig. . water-worn pebbles, upper potomac river, maryland] land forms due to river erosion =river valleys.= in their courses to the sea, rivers follow valleys of various forms, some shallow and some deep, some narrow and some wide. since rivers are known to erode their beds and banks, it is a fair presumption that, aided by the weather, they have excavated the valleys in which they flow. moreover, a bird's-eye view or a map of a region shows the significant fact that the valleys of a system unite with one another in a branch work, as twigs meet their stems and the branches of a tree its trunk. each valley, from that of the smallest rivulet to that of the master stream, is proportionate to the size of the stream which occupies it. with a few explainable exceptions the valleys of tributaries join that of the trunk stream at a level; there is no sudden descent or break in the bed at the point of juncture. these are the natural consequences which must follow if the land has long been worked upon by streams, and no other process has ever been suggested which is competent to produce them. we must conclude that valley systems have been formed by the river systems which drain them, aided by the work of the weather; they are not gaping fissures in the earth's crust, as early observers imagined, but are the furrows which running water has drawn upon the land. as valleys are made by the slow wear of streams and the action of the weather, they pass in their development through successive stages, each of which has its own characteristic features. we may therefore classify rivers and valleys according to the stage which they have reached in their life history from infancy to old age. young river valleys =infancy.= the red river of the north. a region in northwestern minnesota and the adjacent portions of north dakota and manitoba was so recently covered by the waters of an extinct lake, known as lake agassiz, that the surface remains much as it was left when the lake was drained away. the flat floor, spread smooth with lake-laid silts, is still a plain, to the eye as level as the sea. across it the red river of the north and its branches run in narrow, ditch-like channels, steep-sided and shallow, not exceeding sixty feet in depth, their gradients differing little from the general slopes of the region. the trunk streams have but few tributaries; the river system, like a sapling with few limbs, is still undeveloped. along the banks of the trunk streams short gullies are slowly lengthening headwards, like growing twigs which are sometime to become large branches. [illustration: fig. . a young lacustrine plain; the red river of the north scale inches = about miles. contour interval, feet] the flat interstream areas are as yet but little scored by drainage lines, and in wet weather water lingers in ponds in any initial depressions on the plain. [illustration: fig. . a young river, iowa note that it has hardly begun to cut in the plain of glacial drift on which it flows] =contours.= in order to read the topographic maps of the text-book and the laboratory the student should know that contours are lines drawn on maps to represent relief, all points on any given contour being of equal height above sea level. the _contour interval_ is the uniform vertical distance between two adjacent contours and varies on different maps. to express regions of faint relief a contour interval of ten or twenty feet is commonly selected; while in mountainous regions a contour interval of two hundred and fifty, five hundred, or even one thousand feet may be necessary in order that the contours may not be too crowded for easy reading. whether a river begins its life on a lake plain, as in the example just cited, or upon a coastal plain lifted from beneath the sea or on a spread of glacial drift left by the retreat of continental ice sheets, such as covers much of canada and the northeastern parts of the united states, its infantile stage presents the same characteristic features,--a narrow and shallow valley, with undeveloped tributaries and undrained interstream areas. ground water stands high, and, exuding in the undrained initial depressions, forms marshes and lakes. [illustration: fig. . a young drift region in wisconsin describe this area. how high are the hills? are they such in form and position as would be left by stream erosion? consult a map of the entire state and notice that the fox river finds its way to lake michigan, while the wisconsin empties into the mississippi. describe that portion of the divide here shown between the mississippi and the st. lawrence systems. which is the larger river, the wisconsin or the fox? other things being equal, which may be expected to deepen its bed the more rapidly? what changes are likely to occur when one of these rivers comes to flow at a lower level than the other? why have not these changes occurred already?] =lakes.= lakes are perhaps the most obvious of these fleeting features of infancy. they are short-lived, for their destruction is soon accomplished by several means. as a river system advances toward maturity the deepening and extending valleys of the tributaries lower the ground-water surface and invade the undrained depressions of the region. lakes having outlets are drained away as their basin rims are cut down by the outflowing streams,--a slow process where the rim is of hard rock, but a rapid one where it is of soft material such as glacial drift. lakes are effaced also by the filling of their basins. inflowing streams and the wash of rains bring in waste. waves abrade the shore and strew the débris worn from it over the lake bed. shallow lakes are often filled with organic matter from decaying vegetation. does the outflowing stream, from a lake carry sediment? how does this fact affect its erosive power on hard rock? on loose material? lake geneva is a well-known example of a lake in process of obliteration. the inflowing rhone has already displaced the waters of the lake for a length of twenty miles with the waste brought down from the high alps. for this distance there extends up the rhone valley an alluvial plain, which has grown lakeward at the rate of a mile and a half since roman times, as proved by the distance inland at which a roman port now stands. [illustration: fig. . a small lake being broadened and shoaled by wave wear _ls_, lake surface; dotted line, initial shore; _b_, fill made of material taken from _a_] how rapidly a lake may be silted up under exceptionally favorable conditions is illustrated by the fact that over the bottom of the artificial lake, of thirty-five square miles, formed behind the great dam across the colorado river at austin, texas, sediments thirty-nine feet deep gathered in seven years. lake mendota, one of the many beautiful lakes of southern wisconsin, is rapidly cutting back the soft glacial drift of its shores by means of the abrasion of its waves. while the shallow basin is thus broadened, it is also being filled with the waste; and the time is brought nearer when it will be so shoaled that vegetation can complete the work of its effacement. [illustration: fig. . a lake well-nigh effaced, montana by what means is the lake bed being filled?] along the margin of a shallow lake mosses, water lilies, grasses, and other water-loving plants grow luxuriantly. as their decaying remains accumulate on the bottom, the ring of marsh broadens inwards, the lake narrows gradually to a small pond set in the midst of a wide bog, and finally disappears. all stages in this process of extinction may be seen among the countless lakelets which occupy sags in the recent sheets of glacial drift in the northern states; and more numerous than the lakes which still remain are those already thus filled with carbonaceous matter derived from the carbon dioxide of the atmosphere. such fossil lakes are marked by swamps or level meadows underlain with muck. [illustration: fig. . a level meadow, scotland explain its origin. what will be its future?] =the advance to maturity.= the infantile stage is brief. as a river advances toward maturity the initial depressions, the lake basins of its area, are gradually effaced. by the furrowing action of the rain wash and the head ward lengthening, of tributaries a branchwork of drainage channels grows until it covers the entire area, and not an acre is left on which the fallen raindrop does not find already cut for it an uninterrupted downward path which leads it on by way of gully, brook, and river to the sea. the initial surface of the land, by whatever agency it was modeled, is now wholly destroyed; the region is all reduced to valley slopes. [illustration: fig. . drainage maps _a_, an area in its infancy, buena vista county, iowa; _b_, an area in its maturity, ringgold county, iowa] [illustration: fig. . successive longitudinal profiles of a stream _am_, initial profile, with waterfall at _w_, and basins at _l_ and _l´_, which at first are occupied by lakes and later are filled or drained; _b_, _c_, _d_, and _e_, profiles established in succession as the stream advances from infancy toward old age. note that these profiles are concave toward the sky. this is the _erosion curve_. what contrasting form has the weather weather curve (p. )?] =the longitudinal profile of a stream.= this at first corresponds with the initial surface of the region on which the stream begins to flow, although its way may lead through basins and down steep descents. the successive profiles to which it reduces its bed are illustrated in figure . as the gradient, or rate of descent of its bed, is lowered, the velocity of the river is decreased until its lessening energy is wholly consumed in carrying its load and it can no longer erode its bed. the river is now _at grade_, and its capacity is just equal to its load. if now its load is increased the stream deposits, and thus builds up, or _aggrades_, its bed. on the other hand, if its load is diminished it has energy to spare, and resuming its work of erosion, _degrades_ its bed. in either case the stream continues aggrading or degrading until a new gradient is found where the velocity is just sufficient to move the load, and here again it reaches grade. [illustration: fig. . a v-valley,--the canyon of the yellowstone note the steep sides. what processes are at work upon them? how wide is the valley at the base compared with the width of the stream? do you see any river deposits along the banks? is the stream flowing swiftly over a rock bed, or quietly over a bed which it has built up? is it graded or ungraded? note that the canyon walls project in interlocking spurs] =v-valleys.= vigorous rivers well armed with waste make short work of cutting their beds to grade, and thus erode narrow, steep-sided gorges only wide enough at the base to accommodate the stream. the steepness of the valley slopes depends on the relative rates at which the bed is cut down by the stream and the sides are worn back by the weather. in resistant rock a swift, well-laden stream may saw out a gorge whose sides are nearly or even quite vertical, but as a rule young valleys whose streams have not yet reached grade are v-shaped; their sides flare at the top because here the rocks have longest been opened up to the action of the weather. some of the deepest canyons may be found where a rising land mass, either mountain range or plateau, has long maintained by its continued uplift the rivers of the region above grade. [illustration: fig. . section of the yellowstone canyon this canyon is feet deep, feet wide at the top, and about feet wide at the bottom. neglecting any cutting of the river against the banks, estimate what part of the excavation of the canyon is due to the vertical erosion of its bed by the river and what to weathering and rain wash on the canyon sides] in the northern hemisphere the north sides of river valleys are sometimes of more gentle slope than the south sides. can you suggest a reason? =the grand canyon of the colorado river in arizona.= the colorado river trenches the high plateau of northern arizona with a colossal canyon two hundred and eighteen miles long and more than a mile in greatest depth (fig. ). the rocks in which the canyon is cut are for the most part flat-lying, massive beds of limestones and sandstones, with some shales, beneath which in places harder crystalline rocks are disclosed. where the canyon is deepest its walls have been profoundly dissected. lateral ravines have widened into immense amphitheaters, leaving between them long ridges of mountain height, buttressed and rebuttressed with flanking spurs and carved into majestic architectural forms. from the extremity of one of these promontories it is two miles or more across the gulf to the point of the one opposite, and the heads of the amphitheaters are thirteen miles apart. [illustration: fig. . grand canyon of the colorado river, arizona] the lower portion of the canyon is much narrower (fig. ) and its walls of dark crystalline rock sink steeply to the edge of the river, a swift, powerful stream a few hundred feet wide, turbid with reddish silt, by means of which it continually rasps its rocky bed as it hurries on. the colorado is still deepening its gorge. in the grand canyon its gradient is seven and one half feet to the mile, but, as in all ungraded rivers, the descent is far from uniform. graded reaches in soft rock alternate with steeper declivities in hard rock, forming rapids such as, for example, a stretch of ten miles where the fall averages twenty-one feet to the mile. because of these dangerous rapids the few exploring parties who have traversed the colorado canyon have done so at the hazard of their lives. the canyon has been shaped by several agencies. its depth is due to the river which has sawed its way far toward the base of a lofty rising plateau. acting alone this would have produced a slitlike gorge little wider than the breadth of the stream. the impressive width of the canyon and the magnificent architectural masses which fill it are owing to two causes. running water has gulched the walls and weathering has everywhere attacked and driven them back. the horizontal harder beds stand out in long lines of vertical cliffs, often hundreds of feet in height, at whose feet talus slopes conceal the outcrop of the weaker strata (fig. ). as the upper cliffs have been sapped and driven back by the weather, broad platforms are left at their bases and the sides of the canyon descend to the river by gigantic steps. far up and down the canyon the eye traces these horizontal layers, like the flutings of an elaborate molding, distinguishing each by its contour as well as by its color and thickness. [illustration: fig. . diagrams illustrating conditions which produce falls or rapids _a_, vertical succession of harder and softer rocks; _b_, horizontal succession of the same. in _a_ the stream _ab_ in sinking its bed through a mass of strata of different degrees of hardness has discovered the weak layer _s_ beneath the hard layer _h_. it rapidly cuts its way in _s_, while in _a_ its work is delayed. thus the profile _afb´_ is soon reached, with falls at _f_. in _b_ the initial profile is shown by dotted line.] the grand canyon of the colorado is often and rightly cited as an example of the stupendous erosion which may be accomplished by a river. and yet the colorado is a young stream and its work is no more than well begun. it has not yet wholly reached grade, and the great task of the river and its tributaries--the task of leveling the lofty plateau to a low plain and of transporting it grain by grain to the sea--still lies almost entirely in the future. [illustration: fig. . longitudinal section of yellowstone river at lower fall, _f_, and upper fall, _f´_, yellowstone national park _la_, lava deeply decayed through action of thermal waters; _m_ and _m´_, masses of decayed lavas to whose hardness the falls are due. which fall will be worn away the sooner? how far upstream will each fall migrate? draw profile of the river when one fall has disappeared] [illustration: fig. . diagram illustrating migration of a fall due to a hard layer _h_, in the midst of soft layers _s_ and _s_, all dipping upstream _a_, _b_, _c_, _d_, and _e_, successive positions of the fall; _r_, rapid to which the fall is reduced. draw diagram showing migration of fall in strata dipping _downstream_. under what conditions of inclination of the strata will a fall migrate the farthest and have the longest life? under what conditions will it migrate the least distance and soonest be destroyed?] =waterfalls and rapids.= before the bed of a stream is reduced to grade it may be broken by abrupt descents which give rise to waterfalls and rapids. such breaks in a river's bed may belong to the initial surface over which it began its course; still more commonly are they developed in the rock mass through which it is cutting its valley. thus, wherever a stream leaves harder rocks to flow over softer ones the latter are quickly worn below the level of the former, and a sharp change in slope, with a waterfall or rapid, results. at time of flood young tributaries with steeper courses than that of the trunk stream may bring down stones and finer waste, which the gentler current cannot move along, and throw them as a dam across its way. the rapids thus formed are also ephemeral, for as the gradient of the tributaries is lowered the main stream becomes able to handle the smaller and finer load which they discharge. a rare class of falls is produced where the minor tributaries of a young river are not able to keep pace with their master stream in the erosion of their beds because of their smaller volume, and thus join it by plunging over the side of its gorge. but as the river approaches grade and slackens its down cutting, the tributaries sooner or later overtake it, and effacing their falls, unite with it on a level. [illustration: fig. . maturely dissected plateau near charleston, west virginia compare the number of streams in any given number of square miles with the number on an area of the same size in the red river valley (fig. ). what is the shape of the ridges? are their summits broad or narrow? are their crests even or broken by knobs and cols (the depressions on the crest line)? if the latter, how deeply have the cols been worn beneath the summits of the knobs?] waterfalls and rapids of all kinds are evanescent features of a river's youth. like lakes they are soon destroyed, and if any long time had already elapsed since their formation they would have been obliterated already. =local baselevels.= that balanced condition called grade, where a river neither degrades its bed by erosion nor aggrades it by deposition, is first attained along reaches of soft rocks, ungraded outcrops of hard rocks remaining as barriers which give rise to rapids or falls. until these barriers are worn away they constitute local baselevels, below which level the stream, up valley from them, cannot cut. they are eroded to grade one after another, beginning with the least strong, or the one nearest the mouth of the stream. in a similar way the surface of a lake in a river's course constitutes for all inflowing streams a local baselevel, which disappears when the basin is filled or drained. [illustration: fig. . a maturity dissected region of slight relief, iowa] mature and old rivers maturity is the stage of a river's complete development and most effective work. the river system now has well under way its great task of wearing down the land mass which it drains and carrying it particle by particle to the sea. the relief of the land is now at its greatest; for the main channels have been sunk to grade, while the divides remain but little worn below their initial altitudes. ground water now stands low. the run-off washes directly to the streams, with the least delay and loss by evaporation in ponds and marches; the discharge of the river is therefore at its height. the entire region is dissected by stream ways. the area of valley slopes is now largest and sheds to the streams a heavier load of waste than ever before. at maturity the river system is doing its greatest amount of work both in erosion and in the carriage of water and of waste to the sea. [illustration: fig. . successive stages, _a_, _b_, _c_, and _d_, in valley-widening by planation describe valley _a_. what changes have taken place in _b_, _c_, and _d_? do the river bends remain stationary or move up or down valley? with what effect on the projecting spurs of the valley sides? draw diagrams showing a still later stage than _d_] =lateral erosion.= on reaching grade a river ceases to scour its bed, and it does not again begin to do so until some change in load or volume enables it to find grade at a lower level. on the other hand, a stream erodes its banks at all stages in its history, and with graded rivers this process, called lateral erosion, or _planation_, is specially important. the current of a stream follows the outer side of all curves or bends in the channel, and on this side it excavates its bed the deepest and continually wears and saps its banks. on the inner side deposition takes place in the more shallow and slower-moving water. the inner bank of bends is thus built out while the outer bank is worn away. by swinging its curves against the valley sides a graded river continually cuts a wider and wider floor. the v-valley of youth is thus changed by planation to a flat-floored valley with flaring sides which gradually become subdued by the weather to gentle slopes. while widening their valleys streams maintain a constant width of channel, so that a wide-floored valley does not signify that it ever was occupied by a river of equal width. =the gradient.= the gradients of graded rivers differ widely. a large river with a light load reaches grade on a faint slope, while a smaller stream heavily burdened with waste requires a steep slope to give it velocity sufficient to move the load. the platte, a graded river of nebraska with its headwaters in the rocky mountains, is enfeebled by the semi-arid climate of the great plains and surcharged with the waste brought down both by its branches in the mountains and by those whose tracks lie over the soft rocks of the plains. it is compelled to maintain a gradient of eight feet to the mile in western nebraska. the ohio reaches grade with a slope of less than four inches to the mile from cincinnati to its mouth, and the powerful mississippi washes along its load with a fall of but three inches per mile from cairo to the gulf. other things being equal, which of graded streams will have the steeper gradient, a trunk stream or its tributaries? a stream supplied with gravel or one with silt? other factors remaining the same, what changes would occur if the platte should increase in volume? what changes would occur if the load should be increased in amount or in coarseness? [illustration: fig. . successive cross sections of a region as it advances from infancy _a_, to old age _e_] _the old age of rivers._ as rivers pass their prime, as denudation lowers the relief of the region, less waste and finer is washed over the gentler slopes of the lowering hills. with smaller loads to carry, the rivers now deepen their valleys and find grade with fainter declivities nearer the level of the sea. this limit of the level of the sea beneath which they cannot erode is known as _baselevel_.[ ] as streams grow old they approach more and more closely to baselevel, although they are never able to attain it. some slight slope is needed that water may flow and waste be transported over the land. meanwhile the relief of the land has ever lessened. the master streams and their main tributaries now wander with sluggish currents over the broad valley floors which they have planed away; while under the erosion of their innumerable branches and the wear of the weather the divides everywhere are lowered and subdued to more and more gentle slopes. mountains and high plateaus are thus reduced to rolling hills, and at last to plains, surmounted only by such hills as may still be unreduced to the common level, because of the harder rocks of which they are composed or because of their distance from the main erosion channels. such regions of faint relief, worn down to near base level by subaërial agencies, are known as _peneplains_ (almost plains). any residual masses which rise above them are called _monadnocks_, from the name of a conical peak of new hampshire which overlooks the now uplifted peneplain of southern new england. [ ] the term "baselevel" is also used to designate the close approximation to sea level to which streams are able to subdue the land. in its old age a region becomes mantled with thick sheets of fine and weathered waste, slowly moving over the faint slopes toward the water ways and unbroken by ledges of bare rock. in other words, the waste mantle also is now graded, and as waterfalls have been effaced in the river beds, so now any ledges in the wide streams of waste are worn away and covered beneath smooth slopes of fine soil. ground water stands high and may exude in areas of swamp. in youth the land mass was roughhewn and cut deep by stream erosion. in old age the faint reliefs of the land dissolve away, chiefly under the action of the weather, beneath their cloak of waste. [illustration: fig. . peneplain surrounded by monadnocks, piedmont belt, virginia from davis' _elementary physical geography] =the cycle of erosion.= the successive stages through which a land mass passes while it is being leveled to the sea constitute together a cycle of erosion. each stage of the cycle from infancy to old age leaves, as we have seen, its characteristic records in the forms sculptured on the land, such as the shapes of valleys and the contours of hills and plains. the geologist is thus able to determine by the land forms of any region the stage in the erosion cycle to which it now belongs, and knowing what are the earlier stages of the cycle, to read something of the geological history of the region. =interrupted cycles.= so long a time is needed to reduce a land mass to baselevel that the process is seldom if ever completed during a single uninterrupted cycle of erosion. of all the various interruptions which may occur the most important are gradual movements of the earth's crust, by which a region is either depressed or elevated relative to sea level. [illustration: fig. . young inner gorge in wide older valley, alaska] the _depression_ of a region hastens its old age by decreasing the gradient of streams, by destroying their power to excavate their beds and carry their loads to a degree corresponding to the amount of the depression, and by lessening the amount of work they have to do. the slackened river currents deposit their waste in hood plains which increase in height as the subsidence continues. the lower courses of the rivers are invaded by the sea and become estuaries, while the lower tributaries are cut off from the trunk stream. _elevation_, on the other hand, increases the activity of all agencies of weathering, erosion, and transportation, restores the region to its youth, and inaugurates a new cycle of erosion. streams are given a steeper gradient, greater velocity, and increased energy to carry their loads and wear their beds. they cut through the alluvium of their flood plains, leaving it on either bank as successive terraces, and intrench themselves in the underlying rock. in their older and wider valleys they cut narrow, steep-walled inner gorges, in which they flow swiftly over rocky floors, broken here and there by falls and rapids where a harder layer of rock has been discovered. winding streams on plains may thus incise their meanders in solid rock as the plains are gradually uplifted. streams which are thus restored to their youth are said to be _revived_. [illustration: fig. . incised meanders of oneota river, iowa] as streams cut deeper and the valley slopes are steepened, the mantle of waste of the region undergoing elevation is set in more rapid movement. it is now removed particle by particle faster than it forms. as the waste mantle thins, weathering attacks the rocks of the region more energetically until an equilibrium is reached again; the rocks waste rapidly and their waste is as rapidly removed. =dissected peneplains.= when a rise of the land brings one cycle to an end and begins another, the characteristic land forms of each cycle are found together and the topography of the region is composite until the second cycle is so far advanced that the land forms of the first cycle are entirely destroyed. the contrast between the land surfaces of the later and the earlier cycles is most striking when the earlier had advanced to age and the later is still in youth. thus many peneplains which have been elevated and dissected have been recognized by the remnants of their ancient erosion surfaces, and the length of time which has elapsed since their uplift has been measured by the stage to which the new cycle has advanced. [illustration: fig. . describe the valley of stream _a_. is it young or old? how does the valley of _b_ differ from that of _a_? compare as to form and age the inner valley of _b_ with the outer valley and with the valley of _a_. account for the inner valley. why does it not extend to the upper portion of the course of _b_? will it ever do so? draw longitudinal profile of _b_, showing the different gradient of upper and lower portions of its course not here seen. as the inner valley of tributary _c_ extends headward it may invade the valley of _a_ before the inner valley of _a_ has worked upstream to the area seen in the diagram. with what results?] =the piedmont belt.= as an example of an ancient peneplain uplifted and dissected we may cite the piedmont belt, a broad upland lying between the appalachian mountains and the atlantic coastal plain. the surface of the piedmont is gently rolling. the divides, which are often smooth areas of considerable width, rise to a common plane, and from them one sees in every direction an even sky line except where in places some lone hill or ridge may lift itself above the general level (fig. ). the surface is an ancient one, for the mantle of residual waste lies deep upon it, soils are reddened by long oxidation, and the rocks are rotted to a depth of scores of feet. at present, however, the waste mantle is not forming so rapidly as it is being removed. the streams of the upland are actively engaged in its destruction. they flow swiftly in narrow, rock-walled valleys over rocky beds. this contrast between the young streams and the aged surface which they are now so vigorously dissecting can only be explained by the theory that the region once stood lower than at present and has recently been upraised. if now we imagine the valleys refilled with the waste which the streams have swept away, and the upland lowered, we restore the piedmont region to the condition in which it stood before its uplift and dissection,--a gently rolling plain, surmounted here and there by isolated hills and ridges. [illustration: fig. . dissected peneplain of southern new england] the surface of the ancient piedmont plain, as it may be restored from the remnants of it found on the divides, is not in accordance with the structures of the country rocks. where these are exposed to view they are seen to be far from horizontal. on the walls of river gorges they dip steeply and in various directions and the streams flow over their upturned edges. as shown in figure , the rocks of the piedmont have been folded and broken and tilted. [illustration: fig. . section in piedmont belt _m_, a monadnock] it is not reasonable to believe that when the rocks of the piedmont were thus folded and otherwise deformed the surface of the region was a plain. the upturned layers have not always stopped abruptly at the even surface of the piedmont plain which now cuts across them. they are the bases of great folds and tilted blocks which must once have risen high in air. the complex and disorderly structures of the piedmont rocks are those seen in great mountain ranges, and there is every reason to believe that these rocks after their deformation rose to mountain height. [illustration: fig. . the area of the laurentian peneplain (shaded)] the ancient piedmont plain cuts across these upturned rocks as independently of their structure as the even surface of the sawed stump of some great tree is independent of the direction of its fibers. hence the piedmont plain as it was before its uplift was not a coastal plain formed of strata spread in horizontal sheets beneath the sea and then uplifted; nor was it a structural plain, due to the resistance to erosion of some hard, flat-lying layer of rock. even surfaces developed on rocks of discordant structure, such as the piedmont shows, are produced by long denudation, and we may consider the piedmont as a peneplain formed by the wearing down of mountain ranges, and recently uplifted. =the laurentian peneplain.= this is the name given to a denuded surface on very ancient rocks which extends from the arctic ocean to the st. lawrence river and lake superior, with small areas also in northern wisconsin and new york. throughout this u-shaped area, which incloses hudson bay within its arms, the country rocks have the complicated and contorted structures which characterize mountain ranges (see fig. , p. ). but the surface of the area is by no means mountainous. the sky line when viewed from the divides is unbroken by mountain peaks or rugged hills. the surface of the arm west of hudson bay is gently undulating and that of the eastern arm has been roughened to low-rolling hills and dissected in places by such deep river gorges as those of the ottawa and saguenay. this immense area may be regarded as an ancient peneplain truncating the bases of long-vanished mountains and dissected after elevation. in the examples cited the uplift has been a broad one and to comparatively little height. where peneplains have been uplifted to great height and have since been well dissected, and where they have been upfolded and broken and uptilted, their recognition becomes more difficult. yet recent observers have found evidences of ancient lowland surfaces of erosion on the summits of the allegheny ridges, the cascade mountains (fig. ), and the western slope of the sierra nevadas. [illustration: fig. . view in the cascade mountains, washington the general level to which these ridges rise may be accounted for by the uplift and dissection of a once low-lying peneplain] =the southern appalachian region.= we have here an example of an area the latter part of whose geological history may be deciphered by means of its land forms. the generalized section of figure , which passes from west to east across a portion of the region in eastern tennessee, shows on the west a part of the broad cumberland plateau. on the east is a roughened upland platform, from which rise in the distance the peaks of the great smoky mountains. the plateau, consisting of strata but little changed from their original flat-lying attitude, and the platform, developed on rocks of disordered structure made crystalline by heat and pressure, both stand at the common level of the line ab. they are separated by the appalachian valley, forty miles wide, cut in strata which have been folded and broken into long narrow blocks. the valley is traversed lengthwise by long, low ridges, the outcropping edges of the harder strata, which rise to about the same level,--that of the line _cd_. between these ridges stretch valley lowlands at the level _ef_ excavated in the weaker rocks, while somewhat below them lie the channels of the present streams now busily engaged in deepening their beds. _the valley lowlands._ were they planed by graded or ungraded streams? have the present streams reached grade? why did the streams cease widening the floors of the valley lowlands? how long since? when will they begin anew the work of lateral planation? what effect will this have on the ridges if the present cycle of erosion continues long uninterrupted? [illustration: fig. . generalized section of the southern appalachian region in eastern tennessee] _the ridges of the appalachian valley._ why do they stand above the valley lowlands? why do their summits lie in about the same plane? refilling the valleys intervening between these ridges with the material removed by the streams, what is the nature of the surface thus restored? does this surface _cd_ accord with the rock structures on which it has been developed? how may it have been made? at what height did the land stand then, compared with its present height? what elevations stood above the surface _cd_? why? what name may you use to designate them? how does the length of time needed to develop the surface _cd_ compare with that needed to develop the valley lowlands? _the platform and plateau._ why do they stand at a common level ab? of what surface may they be remnants? is it accordant with the rock structure? how was it produced? what unconsumed masses overlooked it? did the rocks of the appalachian valley stand above this surface when it was produced? did they then stand below it? compare the time needed to develop this surface with that needed to develop _cd_. which surface is the older? how many cycles of erosion are represented here? give the erosion history of the region by cycles, beginning with the oldest, the work done in each and the work left undone, what brought each cycle to a close, and how long relatively it continued. chapter iv river deposits the characteristic features of river deposits and the forms which they assume may be treated under three heads: ( ) valley deposits, ( ) basin deposits, and ( ) deltas. valley deposits =flood plains.= the deposits which streams build along their courses at times of flood are known as flood plains. a swift current then sweeps along the channel, while a shallow sheet of water moves slowly over the flood plain, spreading upon it a thin layer of sediment. it has been estimated that each inundation of the nile leaves a layer of fertilizing silt three hundredths of an inch thick over the flood plain of egypt. flood plains may consist of a thin spread of alluvium over the flat rock floor of a valley which is being widened by the lateral erosion of a graded stream (fig. ). flood-plain deposits of great thickness may be built by aggrading rivers even in valleys whose rock floors have never been thus widened (fig. ). [illustration: fig. . cross section of a flood plain] a cross section of a flood plain (fig. ) shows that it is highest next the river, sloping gradually thence to the valley sides. these wide natural embankments are due to the fact that the river deposit is heavier near the bank, where the velocity of the silt-laden channel current is first checked by contact with the slower-moving overflow. [illustration: fig. . waste-filled valley and braided channels of the upper mississippi] thus banked off from the stream, the outer portions of a flood plain are often ill-drained and swampy, and here vegetal deposits, such as peat, may be interbedded with river silts. a map of a wide flood plain, such as that of the mississippi or the missouri (fig. ), shows that the courses of the tributaries on entering it are deflected downstream. why? the aggrading streams by which flood plains are constructed gradually build their immediate banks and beds to higher and higher levels, and therefore find it easy at times of great floods to break their natural embankments and take new courses over the plain. in this way they aggrade each portion of it in turn by means of their shifting channels. =braided channels.= a river actively engaged in aggrading its valley with coarse waste builds a flood plain of comparatively steep gradient and often flows down it in a fairly direct course and through a network of braided channels. from time to time a channel becomes choked with waste, and the water no longer finding room in it breaks out and cuts and builds itself a new way which reunites down valley with the other channels. thus there becomes established a network of ever-changing channels inclosing low islands of sand and gravel. [illustration: fig. . terraced valley of river in central asia] [illustration: fig. . terraces carved in alluvial deposits] which is older, the rock floor of the valley or the river deposits which fill it? what are the relative ages of terraces _a_, _b_, _c_, and _e_? it will be noted that the remnants of the higher flood plains have not been swept away by the meandering river, as it swung from side to side of the valley at lower levels, because they have been defended by ledges of hard rock in the projecting spurs of the initial valley. the stream has encountered such defending ledges at the point marked _d_] [illustration: fig. . river terraces of rock covered with alluvium _c_, recent flood plain of the river. to what processes is it due? account for the alluvium at _a_ and _b_ and on the opposite side of the valley at the same levels. which is the older? account for the flat rock floors on which these deposits of alluvium rest. give the entire history which may be read in the section] =terraces.= while aggrading streams thus tend to shift their channels, degrading streams, on the contrary, become more and more deeply intrenched in their valleys. it often occurs that a stream, after having built a flood plain, ceases to aggrade its bed because of a lessened load or for other reasons, such as an uplift of the region, and begins instead to degrade it. it leaves the original flood plain out of reach of even the highest floods. when again it reaches grade at a lower level it produces a new flood plain by lateral erosion in the older deposits, remnants of which stand as terraces on one or both sides of the valley. in this way a valley may be lined with a succession of terraces at different levels, each level representing an abandoned flood plain. [illustration: fig. . development of a meander the dotted line in _a_, _b_, and _c_ shows the stage preceding that indicate by the unbroken line] =meanders.= valleys aggraded with fine waste form well-nigh level plains over which streams wind from side to side of a direct course in symmetric bends known as meanders, from the name of a winding river of asia minor. the giant mississippi has developed meanders with a radius of one and one half miles, but a little creek may display on its meadow as perfect curves only a rod or so in radius. on the flood plain of either river or creek we may find examples of the successive stages in the development of the meander, from its beginning in the slight initial bend sufficient to deflect the current against the outer side. eroding here and depositing on the inner side of the bend, it gradually reaches first the open bend (fig. , _a_) whose width and length are not far from equal, and later that of the horseshoe meander (fig. , _b_) whose diameter transverse to the course of the stream is much greater than that parallel with it. little by little the neck of land projecting into the bend is narrowed, until at last it is cut through and a "cut-off" is established. the old channel is now silted up at both ends and becomes a crescentic lagoon (fig. , _c_), or oxbow lake, which fills gradually to an arc-shaped shallow depression. [illustration: fig. . map of a portion of the flood plain of the missouri river each small square represents one square mile. how wide is the flood plain of the missouri? how wide is the flood plain of the big sioux? why is the latter river deflected down valley on entering the flood plain of the master stream? how do the meanders of the two rivers compare in size? how does the width of each flood plain compare with the width of the belt occupied by the meanders of the river? do you find traces of any former channels?] =flood plains characteristic of mature rivers.= on reaching grade a stream planes a flat floor for its continually widening valley. ever cutting on the outer bank of its curves, it deposits on the inner bank scroll-like flood-plain patches (fig ). for a while the valley bluffs do not give its growing meanders room to develop to their normal size, but as planation goes on, the bluffs are driven back to the full width of the meander belt and still later to a width which gives room for broad stretches of flood plain on either side (fig. ). usually a river first attains grade near its mouth, and here first sinks its bed to near baselevel. extending its graded course upstream by cutting away barrier after barrier, it comes to have a widened and mature valley over its lower course, while its young headwaters are still busily eroding their beds. its ungraded branches may thus bring down to its lower course more waste than it is competent to carry on to the sea, and here it aggrades its bed and builds a flood plain in order to gain a steeper gradient and velocity enough to transport its load. as maturity is past and the relief of the land is lessened, a smaller and smaller load of waste is delivered to the river. it now has energy to spare and again degrades its valley, excavating its former flood plains and leaving them in terraces on either side, and at last in its old age sweeping them away. [illustration: fig. . alluvial cones, wyoming] =alluvial cones and fans.= in hilly and mountainous countries one often sees on a valley side a conical or fan-shaped deposit of waste at the mouth of a lateral stream. the cause is obvious: the young branch has not been able as yet to wear its bed to accordant level with the already deepened valley of the master stream. it therefore builds its bed to grade at the point of juncture by depositing here its load of waste,--a load too heavy to be carried along the more gentle profile of the trunk valley. [illustration: fig. . tributaries and distributaries of a fan-building stream] where rivers descend from a mountainous region upon the plain they may build alluvial fans of exceedingly gentle slope. thus the rivers of the western side of the sierra nevada mountains have spread fans with a radius of as much as forty miles and a slope too slight to be detected without instruments, where they leave the rock-cut canyons in the mountains and descend upon the broad central valley of california. as a river flows over its fan it commonly divides into a branchwork of shifting channels called _distributaries_, since they lead off the water from the main stream. in this way each part of the fan is aggraded and its symmetric form is preserved. =piedmont plains.= mountain streams may build their confluent fans into widespread piedmont (foot of the mountain) alluvial plains. these are especially characteristic of arid lands, where the streams wither as they flow out upon the thirsty lowlands and are therefore compelled to lay down a large portion of their load. in humid climates mountain-born streams are usually competent to carry their loads of waste on to the sea, and have energy to spare to cut the lower mountain slopes into foothills. in arid regions foothills are commonly absent and the ranges rise, as from pedestals, above broad, sloping plains of stream-laid waste. [illustration: fig. . section from the rocky mountains eastward river deposits dotted] =the high plains.= the rivers which flow eastward from the rocky mountains have united their fans in a continuous sheet of waste which stretches forward from the base of the mountains for hundreds of miles and in places is five hundred feet thick (fig. ). that the deposit was made in ancient times on land and not in the sea is proved by the remains which it contains of land animals and plants of species now extinct. that it was laid by rivers and not by fresh-water lakes is shown by its structure. wide stretches of flat-lying, clays and sands are interrupted by long, narrow belts of gravel which mark the channels of the ancient streams. gravels, and sands are often cross bedded, and their well worn pebbles may be identified with the rocks of the mountains. after building this sheet of waste the streams ceased to aggrade and began the work of destruction. large uneroded remnants, their surfaces flat as a floor, remain as the high plains of western kansas and nebraska. =river deposits in subsiding troughs.= to a geologist the most important river deposits are those which gather in areas of gradual subsidence; they are often of vast extent and immense thickness, and such deposits of past geological ages have not infrequently been preserved, with all their records of the times in which they were built, by being carried below the level of the sea, to be brought to light by a later uplift. on the other hand, river deposits which remain above baselevels of erosion are swept away comparatively soon. =the great valley of california= is a monotonously level plain of great fertility, four hundred miles in length and fifty miles in average width, built of waste swept down by streams from the mountain ranges which inclose it,--the sierra nevada on the east and the coast range on the west. on the waste slopes at the foot of the bordering hills coarse gravels and even bowlders are left, while over the interior the slow-flowing streams at times of flood spread wide sheets of silt. organic deposits are now forming by the decay of vegetation in swampy tule (reed) lands and in shallow lakes which occupy depressions left by the aggrading streams. deep borings show that this great trough is filled to a depth of at least two thousand feet below sea level with recent unconsolidated sands and silts containing logs of wood and fresh-water shells. these are land deposits, and the absence of any marine deposits among them proves that the region has not been invaded by the sea since the accumulation began. it has therefore been slowly subsiding and its streams, although continually carried below grade, have yet been able to aggrade the surface as rapidly as the region sank, and have maintained it, as at present, slightly above sea level. =the indo-gangetic plain=, spread by the brahmaputra, the ganges, and the indus river systems, stretches for sixteen hundred miles along the southern base of the himalaya mountains and occupies an area of three hundred thousand square miles (fig. ). it consists of the flood plains of the master streams and the confluent fans of the tributaries which issue from the mountains on the north. large areas are subject to overflow each season of flood, and still larger tracts mark abandoned flood plains below which the rivers have now cut their beds. the plain is built of far-stretching beds of clay, penetrated by streaks of sand, and also of gravel near the mountains. beds of impure peat occur in it, and it contains fresh-water shells and the bones of land animals of species now living in northern india. at lucknow an artesian well was sunk to one thousand feet below sea level without reaching the bottom of these river-laid sands and silts, proving a slow subsidence with which the aggrading rivers have kept pace. =warped valleys.= it is not necessary that an area should sink below sea level in order to be filled with stream-swept waste. high valleys among growing mountain ranges may suffer warping, or may be blockaded by rising mountain folds athwart them. where the deformation is rapid enough, the river may be ponded and the valley filled with lake-laid sediments. even when the river is able to maintain its right of way it may yet have its declivity so lessened that it is compelled to aggrade its course continually, filling the valley with river deposits which may grow to an enormous thickness. behind the outer ranges of the himalaya mountains lie several waste-filled valleys, the largest of which are kashmir and nepal, the former being an alluvial plain about as large as the state of delaware. the rivers which drain these plains have already cut down their outlet gorges sufficiently to begin the task of the removal of the broad accumulations which they have brought in from the surrounding mountains. their present flood plains lie as much as some hundreds of feet below wide alluvial terraces which mark their former levels. indeed, the horizontal beds of the hundes valley have been trenched to the depth of nearly three thousand feet by the sutlej river. these deposits are recent or subrecent, for there have been found at various levels the remains of land plants and land and fresh-water shells, and in some the bones of such animals as the hyena and the goat, of species or of genera now living. such soft deposits cannot be expected to endure through any considerable length of future time the rapid erosion to which their great height above the level of the sea will subject them. [illustration: fig. . cross section of aggraded valley, showing structure of river deposits] =characteristics of river deposits.= the examples just cited teach clearly the characteristic features of extensive river deposits. these deposits consist of broad, flat-lying sheets of clay and fine sand left by the overflow at time of flood, and traversed here and there by long, narrow strips of coarse, cross-bedded sands and gravels thrown down by the swifter currents of the shifting channels. occasional beds of muck mark the sites of shallow lakelets or fresh-water swamps. the various strata also contain some remains of the countless myriads of animals and plants which live upon the surface of the plain as it is in process of building. river shells such as the mussel, land shells such as those of snails, the bones of fishes and of such land animals as suffer drowning at times of flood or are mired in swampy places, logs of wood, and the stems and leaves of plants are examples of the variety of the remains of land and fresh-water organisms which are entombed in river deposits and sealed away as a record of the life of the time, and as proof that the deposits were laid by streams and not beneath the sea. basin deposits =deposits in dry basins.= on desert areas without outlet to the sea, as on the great basin of the united states and the deserts of central asia, stream-swept waste accumulates indefinitely. the rivers of the surrounding mountains, fed by the rains and melting snows of these comparatively moist elevations, dry and soak away as they come down upon the arid plains. they are compelled to lay aside their entire load of waste eroded from the mountain valleys, in fans which grow to enormous size, reaching in some instances thousands of feet in thickness. the monotonous levels of turkestan include vast alluvial tracts now in process of building by the floods of the frequently shifting channels of the oxus and other rivers of the region. for about seven hundred miles from its mouth in aral lake the oxus receives no tributaries, since even the larger branches of its system are lost in a network of distributaries and choked with desert sands before they reach their master stream. these aggrading rivers, which have channels but no valleys, spread their muddy floods--which in the case of the oxus sometimes equal the average volume of the mississippi--far and wide over the plain, washing the bases of the desert dunes. =playas.= in arid interior basins the central depressions may be occupied by playas,--plains of fine mud washed forward from the margins. in the wet season the playa is covered with a thin sheet of muddy water, a playa lake, supplied usually by some stream at flood. in the dry season the lake evaporates, the river which fed it retreats, and there is left to view a hard, smooth, level floor of sun-baked and sun-cracked yellow clay utterly devoid of vegetation. in the black rock desert of nevada a playa lake spreads over an area fifty miles long and twenty miles wide. in summer it disappears; the quinn river, which feeds it, shrinks back one hundred miles toward its source, leaving an absolutely barren floor of clay, level as the sea. =lake deposits.= regarding lakes as parts of river systems, we may now notice the characteristic features of the deposits in lake basins. soundings in lakes of considerable size and depth show that their bottoms are being covered with tine clays. sand and gravel are found along; their margins, being brought in by streams and worn by waves from the shore, but there are no tidal or other strong currents to sweep coarse waste out from shore to any considerable distance. where fine clays are now found on the land in even, horizontal layers containing the remains of fresh-water animals and plants, uncut by channels tilled with cross-bedded gravels and sands and bordered by beach deposits of coarse waste, we may safely infer the existence of ancient lakes. =marl.= marl is a soft, whitish deposit of carbonate of lime, mingled often with more or less of clay, accumulated in small lakes whose feeding springs are charged with carbonate of lime and into which little waste is washed from the land. such lakelets are not infrequent on the surface of the younger drift sheets of michigan and northern indiana, where their beds of marl--sometimes as much as forty feet thick--are utilized in the manufacture of portland cement. the deposit results from the decay of certain aquatic plants which secrete lime carbonate from the water, from the decomposition of the calcareous shells of tiny mollusks which live in countless numbers on the lake floor, and in some cases apparently from chemical precipitation. =peat.= we have seen how lakelets are extinguished by the decaying remains of the vegetation which they support. a section of such a fossil lake shows that below the growing mosses and other plants of the surface of the bog lies a spongy mass composed of dead vegetable tissue, which passes downward gradually into _peat_,--a dense, dark brown carbonaceous deposit in which, to the unaided eye, little or no trace of vegetable structure remains. when dried, peat forms a fuel of some value and is used either cut into slabs and dried or pressed into bricks by machinery. [illustration: fig. . digging peat, scotland] when vegetation decays in open air the carbon of its tissues, taken from the atmosphere by the leaves, is oxidized and returned to it in its original form of carbon dioxide. but decomposing in the presence of water, as in a bog, where the oxygen of the air is excluded, the carbonaceous matter of plants accumulates in deposits of peat. peat bogs are numerous in regions lately abandoned by glacier ice, where river systems are so immature that the initial depressions left in the sheet of drift spread over the country have not yet been drained. one tenth of the surface of ireland is said to be covered with peat, and small bogs abound in the drift-covered area of new england and the states lying as far west as the missouri river. in massachusetts alone it has been reckoned that there are fifteen billion cubic feet of peat, the largest bog occupying several thousand acres. much larger swamps occur on the young coastal plain of the atlantic from new jersey to florida. the dismal swamp, for example, in virginia and north carolina is forty miles across. it is covered with a dense growth of water-loving trees such as the cypress and black gum. the center of the swamp is occupied by lake drummond, a shallow lake seven miles in diameter, with banks of pure-peat, and still narrowing from the encroachment of vegetation along its borders. =salt lakes.= in arid climates a lake rarely receives sufficient inflow to enable it to rise to the basin rim and find an outlet. before this height is reached its surface becomes large enough to discharge by evaporation into the dry air the amount of water that is supplied by streams. as such a lake has no outlet, the minerals in solution brought into it by its streams cannot escape from the basin. the lake water becomes more and more heavily charged with such substances as common salt and the sulphates and carbonates of lime, of soda, and of potash, and these are thrown down from solution one after another as the point of saturation for each mineral is reached. carbonate of lime, the least soluble and often the most abundant mineral brought in, is the first to be precipitated. as concentration goes on, gypsum, which is insoluble in a strong brine, is deposited, and afterwards common salt. as the saltness of the lake varies with the seasons and with climatic changes, gypsum and salt are laid in alternate beds and are interleaved with sedimentary clays spread from the waste brought in by streams at times of flood. few forms of life can live in bodies of salt water so concentrated that chemical deposits take place, and hence the beds of salt, gypsum, and silt of such lakes are quite barren of the remains of life. similar deposits are precipitated by the concentration of sea water in lagoons and arms of the sea cut off from the ocean. [illustration: fig. . map of lake bonneville and lahontan from davis' _physical geography_] =lakes bonneville and lahontan.= these names are given to extinct lakes which once occupied large areas in the great basin, the former in utah, the latter in northwestern nevada. their records remain in old horizontal beach lines which they drew along their mountainous shores at the different levels at which they stood, and in the deposits of their beds. at its highest stage lake bonneville, then one thousand feet deep, overflowed to the north and was a fresh-water lake. as it shrank below the outlet it became more and more salty, and the great salt lake, its withered residue, is now depositing salt along its shores. in its strong brine lime carbonate is insoluble, and that brought in by streams is thrown down at once in the form of travertine. [illustration: fig. . section of deposits in beds of lakes bonneville and lahontan] lake lahontan never had an outlet. the first chemical deposits to be made along its shores were deposits of travertine, in places eighty feet thick. its floor is spread with fine clays, which must have been laid in deep, still water, and which are charged with the salts absorbed by them as the briny water of the lake dried away. these sedimentary clays are in two divisions, the upper and lower, each being about one hundred feet thick (_a_ and _c_, fig. ). they are separated by heavy deposits of well-rounded, cross-bedded gravels and sands (_b_, fig. ), similar to those spread at the present time by the intermittent streams of arid regions. a similar record is shown in the old floors of lake bonneville. what conclusions do you draw from these facts as to the history of these ancient lakes? deltas in the river deposits which are left above sea level particles of waste are allowed to linger only for a time. from alluvial fans and flood plains they are constantly being taken up and swept farther on downstream. although these land forms may long persist, the particles which compose them are ever changing. we may therefore think of the alluvial deposits of a valley as a stream of waste fed by the waste mantle as it creeps and washes down the valley sides, and slowly moving onwards to the sea. in basins waste finds a longer rest, but sooner or later lakes and dry basins are drained or filled, and their deposits, if above sea level, resume their journey to their final goal. it is only when carried below the level of the sea that they are indefinitely preserved. on reaching this terminus, rivers deliver their load to the ocean. in some cases the ocean is able to take it up by means of strong tidal and other currents, and to dispose of it in ways which we shall study later. but often the load is so large, or the tides are so weak, that much of the waste which the river brings in settles at its mouth, there building up a deposit called the _delta_, from the greek letter (d) of that name, whose shape it sometimes resembles. deltas and alluvial fans have many common characteristics. both owe their origin to a sudden check in the velocity of the river, compelling a deposit of the load; both are triangular in outline, the apex pointing upstream; and both are traversed by distributaries which build up all parts in turn. in a delta we may distinguish deposits of two distinct kinds,--the submarine and the subaërial. in part a delta is built of waste brought down by the river and redistributed and spread by waves and tides over the sea bottom adjacent to the river's mouth. the origin of these deposits is recorded in the remains of marine animals and plants which they contain. [illustration: fig. . delta of the mississippi river] as the submarine delta grows near to the level of the sea the distributaries of the river cover it with subaërial deposits altogether similar to those of the flood plain, of which indeed the subaërial delta is the prolongation. here extended deposits of peat may accumulate in swamps, and the remains of land and fresh-water animals and plants swept down by the stream are imbedded in the silts laid at times of flood. borings made in the deltas of great rivers such as the mississippi, the ganges, and the nile, show that the subaërial portion often reaches a surprising thickness. layers of peat, old soils, and forest grounds with the stumps of trees are discovered hundreds of feet below sea level. in the nile delta some eight layers of coarse gravel were found interbedded with river silts, and in the ganges delta at calcutta a boring nearly five hundred feet in depth stopped in such a layer. the mississippi has built a delta of twelve thousand three hundred square miles, and is pushing the natural embankments of its chief distributaries into the gulf at a maximum rate of a mile in sixteen years. muddy shoals surround its front, shallow lakes, e.g. lakes pontchartrain and borgne, are formed between the growing delta and the old shore line, and elongate lakes and swamps are inclosed between the natural embankments of the distributaries. the delta of the indus river, india, lies so low along shore that a broad tract of country is overflowed by the highest tides. the submarine portion of the delta has been built to near sea level over so wide a belt offshore that in many places large vessels cannot come even within sight of land because of the shallow water. [illustration: fig. . radial section of a delta this section of a delta illustrates the structure of the platform which swift streams well loaded with coarse waste build in the water bodies into which they empty. three members may be distinguished: the _bottom set beds_, _a_: the _fore set beds_, _b_; and the _top set beds_, _c_. account for the slope of each of these. why are the bottom set beds of the finer material and why do they extend beyond the others? how does the profile of this delta differ from that of an alluvial cone and why?] a former arm of the sea, the rann of cutch, adjoining the delta on the east has been silted up and is now an immense barren flat of sandy mud two hundred miles in length and one hundred miles in greatest breadth. each summer it is flooded with salt water when the sea is brought in by strong southwesterly monsoon winds, and the climate during the remainder of the year is hot and dry. by the evaporation of sea water the soil is thus left so salty that no vegetation can grow upon it, and in places beds of salt several feet in thickness have accumulated. under like conditions salt beds of great thickness have been formed in the past and are now found buried among the deposits of ancient deltas. =subsidence of great deltas.= as a rule great deltas are slowly sinking. in some instances upbuilding by river deposits has gone on as rapidly as the region has subsided. the entire thickness of the ganges delta, for example, so far as it has been sounded, consists of deposits laid in open air. in other cases interbedded limestones and other sedimentary rocks containing marine fossils prove that at times subsidence has gained on the upbuilding and the delta has been covered with the sea. it is by gradual depression that delta deposits attain enormous thickness, and, being lowered beneath the level of the sea, are safely preserved from erosion until a movement of the earth's crust in the opposite direction lifts them to form part of the land. we shall read later in the hard rocks of our continent the records of such ancient deltas, and we shall not be surprised to find them as thick as are those now building at the mouths of great rivers. =lake deltas.= deltas are also formed where streams lose their velocity on entering the still waters of lakes. the shore lines of extinct lakes, such as lake agassiz and lakes bonneville and lahontan, may be traced by the heavy deposits at the mouths of their tributary streams. * * * * * we have seen that the work of streams is to drain the lands of the water poured upon them by the rainfall, to wear them down, and to carry their waste away to the sea, there to be rebuilt by other agents into sedimentary rocks. the ancient strata of which the continents are largely made are composed chiefly of material thus worn from still more ancient lands--lands with their hills and valleys like those of to-day--and carried by their rivers to the ocean. in all geological times, as at the present, the work of streams has been to destroy the lands, and in so doing to furnish to the ocean the materials from which the lands of future ages were to be made. before we consider how the waste of the land brought in by streams is rebuilt upon the ocean floor, we must proceed to study the work of two agents, glacier ice and the wind, which coöperate with rivers in the denudation of the land. [illustration: fig. . section of undifferentiated drift near chicago] chapter v the work of glaciers =the drift.= the surface of northeastern north america, as far south as the ohio and missouri rivers, is generally covered by the drift,--a formation which is quite unlike any which we have so far studied. a section of it, such as that illustrated in figure , shows that for the most part it is unstratified, consisting of clay, sand, pebbles, and even large bowlders, all mingled pell-mell together. the agent which laid the drift is one which can carry a load of material of all sizes, from the largest bowlder to the finest clay, and deposit it without sorting. [illustration: fig. . characteristic pebbles from the drift no. has six facets; no. , originally a rounded river pebble, has been nibbled down to one flat face; nos. and are battered subangular fragments on one side only] the stones of the drift are of many kinds. the region from which it was gathered may well have been large in order to supply these many different varieties of rocks. pebbles and bowlders have been left far from their original homes, as may be seen in southern iowa, where the drift contains nuggets of copper brought from the region about lake superior. the agent which laid the drift is one able to gather its load over a large area and carry it a long way. [illustration: fig. . smoothed and scored rock surface exposed to view by the removal of overlying drift, iowa] the pebbles of the drift are unlike those rounded by running water or by waves. they are marked with scratches. some are angular, many have had their edges blunted, while others have been ground flat and smooth on one or more sides, like gems which have been faceted by being held firmly against the lapidary's wheel (fig. ). in many places the upper surface of the country rock beneath the drift has been swept clean of residual clays and other waste. all rock rotten has been planed away, and the ledges of sound rock to which the surface has been cut down have been rubbed smooth and scratched with long, straight, parallel lines (fig. ). the agent which laid the drift can hold sand and pebbles firmly in its grasp and can grind them against the rock beneath, thus planing it down and scoring it, while faceting the pebbles also. neither water nor wind can do these things. indeed, nothing like the drift is being formed by any process now at work anywhere in the eastern united states. to find the agent which has laid this extensive formation we must go to a region of different climatic conditions. [illustration: fig. . map of greenland glacier ice covers all but the areas shaded] =the inland ice of greenland.= greenland is about fifteen hundred miles long and nearly seven hundred miles in greatest width. with the exception of a narrow fringe of mountainous coast land, it is completely buried beneath a sheet of ice, in shape like a vast white shield, whose convex surface rises to a height of nine thousand feet above the sea. the few explorers who have crossed the ice cap found it a trackless desert destitute of all life save such lowly forms as the microscopic plant which produces the so-called "red snow." on the smooth plain of the interior no rock waste relieves the snow's dazzling whiteness; no streams of running water are seen; the silence is broken only by howling storm winds and the rustle of the surface snow which they drive before them. sounding with long poles, explorers find that below the powdery snow of the latest snowfall lie successive layers of earlier snows, which grow more and more compact downward, and at last have altered to impenetrable ice. the ice cap formed by the accumulated snows of uncounted centuries may well be more than a mile in depth. ice thus formed by the compacting of snow is distinguished when in motion as _glacier ice_. [illustration: fig. . hypothetical cross section of greenland] the inland ice of greenland moves. it flows with imperceptible slowness under its own weight, like, a mass of some viscous or plastic substance, such as pitch or molasses candy, in all directions outward toward the sea. near the edge it has so thinned that mountain peaks are laid bare, these islands in the sea of ice being known as _nunataks_. down the valleys of the coastal belt it drains in separate streams of ice, or _glaciers_. the largest of these reach the sea at the head of inlets, and are therefore called _tide glaciers_. their fronts stand so deep in sea water that there is visible seldom more than three hundred feet of the wall of ice, which in many glaciers must be two thousand and more feet high. from the sea walls of tide glaciers great fragments break off and float away as icebergs. thus snows which fell in the interior of this northern land, perhaps many thousands of years ago, are carried in the form of icebergs to melt at last in the north atlantic. greenland, then, is being modeled over the vast extent of its interior not by streams of running water, as are regions in warm and humid climates, nor by currents of air, as are deserts to a large extent, but by a sheet of flowing ice. what the ice sheet is doing in the interior we may infer from a study of the separate glaciers into which it breaks at its edge. =the smaller greenland glaciers.= many of the smaller glaciers of greenland do not reach the sea, but deploy on plains of sand and gravel. the edges of these ice tongues are often as abrupt as if sliced away with a knife (fig. ), and their structure is thus readily seen. they are stratified, their layers representing in part the successive snowfalls of the interior of the country. the upper layers are commonly white and free from stones; but the lower layers, to the height of a hundred feet or more, are dark with debris which is being slowly carried on. so thickly studded with stones is the base of the ice that it is sometimes difficult to distinguish it from the rock waste which has been slowly dragged beneath the glacier or left about its edges. the waste beneath and about the glacier is unsorted. the stones are of many kinds, and numbers of them have been ground to flat faces. where the front of the ice has retreated the rock surface is seen to be planed and scored in places by the stones frozen fast in the sole of the glacier. [illustration: fig. . a greenland glacier] we have now found in glacier ice an agent able to produce the drift of north america. the ice sheet of greenland is now doing what we have seen was done in the recent past in our own land. it is carrying for long distances rocks of many kinds gathered, we may infer, over a large extent of country. it is laying down its load without assortment in unstratified deposits. it grinds down and scores the rock over which it moves, and in the process many of the pebbles of its load are themselves also ground smooth and scratched. since this work can be done by no other agent, we must conclude that the northeastern part of our own continent was covered in the recent past by glacier ice, as greenland is to-day. valley glaciers the work of glacier ice can be most conveniently studied in the separate ice streams which creep down mountain valleys in many regions such as alaska, the western mountains of the united states and canada, the himalayas, and the alps. as the glaciers of the alps have been studied longer and more thoroughly than any others, we shall describe them in some detail as examples of valley glaciers in all parts of the world. =conditions of glacier formation.= the condition of the great accumulation of snow to which glaciers are due--that more or less of each winter's snow should be left over unmelted and unevaporated to the next--is fully met in the alps. there is abundant moisture brought by the winds from neighboring seas. the currents of moist air driven up the mountain slopes are cooled by their own expansion as they rise, and the moisture which they contain is condensed at a temperature at or below ° f., and therefore is precipitated in the form of snow. the summers are cool and their heat does not suffice to completely melt the heavy snow of the preceding winter. on the alps the _snow line_--the lower limit of permanent snow--is drawn at about eight thousand five hundred feet above sea level. above the snow line on the slopes and crests, where these are not too steep, the snow lies the year round and gathers in valley heads to a depth of hundreds of feet. [illustration: fig. . glaciers heading in snow-filled amphitheaters, the alps] [illustration: fig. . bergschrund of a glacier in colorado] this is but a small fraction of the thickness to which snow would be piled on the alps were it not constantly being drained away. below the snow fields which mantle the heights the mountain valleys are occupied by glaciers which extend as much as a vertical mile below the snow line. the presence in the midst of forests and meadows and cultivated fields of these tongues of ice, ever melting and yet from year to year losing none of their bulk, proves that their loss is made good in the only possible way. they are fed by snow fields above, whose surplus of snow they drain away in the form of ice. the presence of glaciers below the snow line is a clear proof that, rigid and motionless as they appear, glaciers really are in constant motion down valley. =the névé field.= the head of an alpine valley occupied by a glacier is commonly a broad amphitheater deeply filled with snow (fig. ). great peaks tower above it, and snowy slopes rise on either side on the flanks of mountain spurs. from these heights fierce winds drift the snows into the amphitheater, and avalanches pour in their torrents of snow and waste. the snow of the amphitheater is like that of drifts in late winter after many successive thaws and freezings. it is made of hard grains and pellets and is called _névé_. beneath the surface of the névé field and at its outlet the granular névé has been compacted to a mass of porous crystalline ice. snow has been changed to névé, and névé to glacial ice, both by pressure, which drives the air from the interspaces of the snowflakes, and also by successive meltings and freezings, much as a snowball is packed in the warm hand and becomes frozen to a ball of ice. [illustration: fig. . sea wall of the muir glacier, alaska] =the bergschrund.= the névé is in slow motion. it breaks itself loose from the thinner snows about it, too shallow to share its motion, and from the rock rim which surrounds it, forming a deep fissure called the bergschrund, sometimes a score and more feet wide (fig. ). =size of glaciers.= the ice streams of the alps vary in size according to the amount of precipitation and the area of the névé fields which they drain. the largest of alpine glaciers, the aletsch, is nearly ten miles long and has an average width of about a mile. the thickness of some of the glaciers of the alps is as much as a thousand feet. giant glaciers more than twice the length of the longest in the alps occur on the south slope of the himalaya mountains, which receive frequent precipitations of snow from moist winds from the indian ocean. the best known of the many immense glaciers of alaska, the muir, has an area of about eight hundred square miles (fig. ). [illustration: fig. . diagram showing movement of row of stakes _a_, set in a direct line across the surface of a glacier; _b_, _c_, and _d_, successive later positions of the stakes] [illustration: fig. . diagram showing movement of vertical row of stakes _a_, set on side of glacier] =glacier motion.= the motion of the glaciers of the alps seldom exceeds one or two feet a day. large glaciers, because of the enormous pressure of their weight and because of less marginal resistance, move faster than small ones. the muir advances at the rate of seven feet a day, and some of the larger tide glaciers of greenland are reported to move at the exceptional rate of fifty feet and more in the same time. glaciers move faster by day than by night, and in summer than in winter. other laws of glacier motion may be discovered by a study of figures and . it is important to remember that glaciers do not slide bodily over their beds, but urged by gravity move slowly down valley in somewhat the same way as would a stream of thick mud. although small pieces of ice are brittle, the large mass of granular ice which composes a glacier acts as a viscous substance. [illustration: fig. . crevasses of a glacier, canada] =crevasses.= slight changes of slope in the glacier bed, and the different rates of motion in different parts, produce tensions under which the ice cracks and opens in great fissures called crevasses. at an abrupt descent in the bed the ice is shattered into great fragments, which unite again below the icefall. crevasses are opened on lines at right angles to the direction of the tension. _transverse crevasses_ are due to a convexity in the bed which stretches the ice lengthwise (fig. ). _marginal crevasses_ are directed upstream and inwards; _radial crevasses_ are found where the ice stream deploys from some narrow valley and spreads upon some more open space. what is the direction of the tension which causes each and to what is it due? (figs. and ). [illustration: fig. . longitudinal section of a portion of a glacier, showing traverse crevasses] [illustration: fig. . map view of marginal crevasses] [illustration: fig. . the rhone glacier, showing radial crevasses, the alps] [illustration: fig. . map view of the junction of two branches of a glacier the moraines are represented by broken lines] =lateral and medial moraines.= the surface of a glacier is striped lengthwise by long dark bands of rock debris. those in the center are called the medial moraines. the one on either margin is a lateral moraine, and is clearly formed of waste which has fallen on the edge of the ice from the valley slopes. a medial moraine cannot be formed in this way, since no rock fragments can fall so far out from the sides. but following it up the glacial stream, one finds that a medial moraine takes its beginning at the junction of the glacier and some tributary and is formed by the union of their two adjacent lateral moraines (fig. ). each branch thus adds a medial moraine, and by counting the number of medial moraines of a trunk stream one may learn of how many branches it is composed. [illustration: fig. . cross section of a glacier showing lateral moraines _l_, _l_, and medial moraines _m_, _m_] surface moraines appear in the lower course of the glacier as ridges, which may reach the exceptional height of one hundred feet. the bulk of such a ridge is ice. it has been protected from the sun by the veneer of moraine stuff; while the glacier surface on either side has melted down at least the distance of the height of the ridge. in summer the lowering of the glacial surface by melting goes on rapidly. in swiss glaciers it has been estimated that the average lowering of the surface by melting and evaporation amounts to ten feet a year. as a moraine ridge grows higher and more steep by the lowering of the surface of the surrounding ice, the stones of its cover tend to slip down its sides. thus moraines broaden, until near the terminus of a glacier they may coalesce in a wide field of stony waste. [illustration: fig. . glacier with medial moraines, the alps is the ice moving from or towards the observer?] =englacial drift.= this name is applied to whatever debris is carried within the glacier. it consists of rock waste fallen on the névé and there buried by accumulations of snow, and of that engulfed in the glacier where crevasses have opened beneath a surface moraine. as the surface of the glacier is lowered by melting, more or less englacial drift is brought again to open air, and near the terminus it may help to bury the ice from view beneath a sheet of debris. =the ground moraine.= the drift dragged along at the glacier's base and lodged beneath it is known as the ground moraine. part of the material of it has fallen down deep crevasses and part has been torn and worn from the glacier's bed and banks. while the stones of the surface moraines remain as angular as when they lodged on the ice, many of those of the ground moraine have been blunted on the edges and faceted and scratched by being ground against one another and the rocky bed. in glaciers such as those of greenland, whose basal layers are well loaded with drift and whose surface layers are nearly clean, different layers have different rates of motion, according to the amount of drift with which they are clogged. one layer glides over another, and the stones inset in each are ground and smoothed and scratched. usually the sides of glaciated pebbles are more worn than the ends, and the scratches upon them run with the longer axis of the stone. why? =the terminal moraine.= as a glacier is in constant motion, it brings to its end all of its load except such parts of the ground moraine as may find permanent lodgment beneath the ice. where the glacier front remains for some time at one place, there is formed an accumulation of drift known as the terminal moraine. in valley glaciers it is shaped by the ice front to a crescent whose convex side is downstream. some of the pebbles of the terminal moraine are angular, and some are faceted and scored, the latter having come by the hard road of the ground moraine. the material of the dump is for the most part unsorted, though the water of the melting ice may find opportunity to leave patches of stratified sands and gravels in the midst of the unstratified mass of drift, and the finer material is in places washed away. [illustration: fig. . terminal moraine of a glacier in montana the ice has melted back from the morainic ridge on the left and is building another on the right. the hollow between the ridges is occupied by a lakelet.] =glacier drainage.= the terminal moraine is commonly breached by a considerable stream, which issues from beneath the ice by a tunnel whose portal has been enlarged to a beautiful archway by melting in the sun and the warm air (fig. ). the stream is gray with silt and loaded with sand and gravel washed from the ground moraine. "glacier milk" the swiss call this muddy water, the gray color of whose silt proves it rock flour freshly ground by the ice from the unoxidized sound rock of its bed, the mud of streams being yellowish when it is washed from the oxidized mantle of waste. since glacial streams are well loaded with waste due to vigorous ice erosion, the valley in front of the glacier is commonly aggraded to a broad, flat floor. these outwash deposits are known as _valley drift_. [illustration: fig. . heavy moraine about the terminus of a glacier in the rocky mountains of canada account for the fact that the morainic ridge rises considerably above the surface of the ice] the sand brought out by streams from beneath a glacier differs from river sand in that it consists of freshly broken angular grains. why? the stream derives its water chiefly from the surface melting of the glacier. as the ice is touched by the rays of the morning sun in summer, water gathers in pools, and rills trickle and unite in brooklets which melt and cut shallow channels in the blue ice. the course of these streams is short. soon they plunge into deep wells cut by their whirling waters where some crevasse has begun to open across their path. these wells lead into chambers and tunnels by which sooner or later their waters find way to the rock floor of the valley and there unite in a subglacial stream. [illustration: fig. . subglacial stream issuing from tunnel in the ice, norway] =the lower limit of glaciers.= the glaciers of a region do not by any means end at a uniform height above sea level. each terminates where its supply is balanced by melting. those therefore which are fed by the largest and deepest névés and those also which are best protected from the sun by a northward exposure or by the depth of their inclosing valleys flow to lower levels than those whose supply is less and whose exposure to the sun is greater. a series of cold, moist years, with an abundant snowfall, causes glaciers to thicken and advance; a series of warm, dry years causes them to wither and melt back. the variation in glaciers is now carefully observed in many parts of the world. the muir glacier has retreated two miles in twenty years. the glaciers of the swiss alps are now for the most part melting back, although a well-known glacier of the eastern alps, the vernagt, advanced five hundred feet in the year , and was then plowing up its terminal moraine. how soon would you expect a glacier to advance after its névé fields have been swollen with unusually heavy snows, as compared with the time needed for the flood of a large river to reach its mouth after heavy rains upon its headwaters? [illustration: fig. . a glacier table] on the surface of glaciers in summer time one may often see large stones supported by pillars of ice several feet in height (fig. ). these "glacier tables" commonly slope more or less strongly to the south, and thus may be used to indicate roughly the points of the compass. can you explain their formation and the direction of their slope? on the other hand, a small and thin stone, or a patch of dust, lying on the ice, tends to sink a few inches into it. why? in what respects is a valley glacier like a mountain stream which flows out upon desert plains? two confluent glaciers do not mingle their currents as do two confluent rivers. what characteristics of surface moraines prove this fact? what effect would you expect the laws of glacier motion to have on the slant of the sides of transverse crevasses? [illustration: fig. . map of malaspina glacier, alaska] a trunk glacier has four medial moraines. of how many tributaries is it composed? illustrate by diagram. state all the evidences which you have found that glaciers move. if a glacier melts back with occasional pauses up a valley, what records are left of its retreat? [illustration: fig. . outwash plain, the delta of the yahtse river, alaska] piedmont glaciers =the malaspina glacier.= piedmont (foot of the mountain) glaciers are, as the name implies, ice fields formed at the foot of mountains by the confluence of valley glaciers. the malaspina glacier of alaska, the typical glacier of this kind, is seventy miles wide and stretches for thirty miles from the foot of the mount saint elias range to the shore of the pacific ocean. the valley glaciers which unite and spread to form this lake of ice lie above the snow line and their moraines are concealed beneath névé. the central area of the malaspina is also free from debris; but on the outer edge large quantities of englacial drift are exposed by surface melting and form a belt of morainic waste a few feet thick and several miles wide, covered in part with a luxuriant forest, beneath which the ice is in places one thousand feet in depth. the glacier here is practically stagnant, and lakes a few hundred yards across, which could not exist were the ice in motion and broken with crevasses, gather on their beds sorted waste from the moraine. the streams which drain the glacier have cut their courses in englacial and subglacial tunnels; none flow for any distance on the surface. the largest, the yahtse river, issues from a high archway in the ice,--a muddy torrent one hundred feet wide and twenty feet deep, loaded with sand and stones which it deposits in a broad outwash plain (fig. ). where the ice has retreated from the sea there is left a hummocky drift sheet with hollows filled with lakelets. these deposits help to explain similar hummocky regions of drift and similar plains of coarse, water-laid material often found in the drift-covered area of the northeastern united states. the geological work of glacier ice the sluggish glacier must do its work in a different way from the agile river. the mountain stream is swift and small, and its channel occupies but a small portion of the valley. the glacier is slow and big; its rate of motion may be less than a millionth of that of running water over the same declivity, and its bulk is proportionately large and fills the valley to great depth. moreover, glacier ice is a solid body plastic under slowly applied stresses, while the water of rivers is a nimble fluid. =transportation.= valley glaciers differ from rivers as carriers in that they float the major part of their load upon their surface, transporting the heaviest bowlder as easily as a grain of sand; while streams push and roll much of their load along their beds, and their power of transporting waste depends solely upon their velocity. the amount of the surface load of glaciers is limited only by the amount of waste received from the mountain slopes above them. the moving floor of ice stretched high across a valley sweeps along as lateral moraines much of the waste which a mountain stream would let accumulate in talus and alluvial cones. while a valley glacier carries much of its load on top, an ice sheet, such as that of greenland, is free from surface debris, except where moraines trail away from some nunatak. if at its edge it breaks into separate glaciers which drain down mountain valleys, these tongues of ice will carry the selvages of waste common to valley glaciers. both ice sheets and valley glaciers drag on large quantities of rock waste in their ground moraines. stones transported by glaciers are sometimes called erratics. such are the bowlders of the drift of our northern states. erratics may be set down in an insecure position on the melting of the ice. =deposit.= little need be added here to what has already been said of ground and terminal moraines. all strictly glacial deposits are unstratified. the load laid down at the end of a glacier in the terminal moraine is loose in texture, while the drift lodged beneath the glacier as ground moraine is often an extremely dense, stony clay, having been compacted under the pressure of the overriding ice. =erosion.= a glacier erodes its bed and banks in two ways,--by abrasion and by plucking. the rock bed over which a glacier has moved is seen in places to have been abraded, or ground away, to smooth surfaces which are marked by long, straight, parallel scorings aligned with the line of movement of the ice and varying in size from hair lines and coarse scratches to exceptional furrows several feet deep. clearly this work has been accomplished by means of the sharp sand, the pebbles, and the larger stones with which the base of the glacier is inset, and which it holds in a firm grasp as running water cannot. hard and fine-grained rocks, such as granite and quartzite, are often not only ground down to a smooth surface but are also highly polished by means of fine rock flour worn from the glacier bed. in other places the bed of the glacier is rough and torn. the rocks have been disrupted and their fragments have been carried away,--a process known as _plucking_. moving under immense pressure the ice shatters the rock, breaks off projections, presses into crevices and wedges the rocks apart, dislodges the blocks into which the rock is divided by joints and bedding planes, and freezing fast to the fragments drags them on. in this work the freezing and thawing of subglacial waters in any cracks and crevices of the rock no doubt play an important part. plucking occurs especially where the bed rock is weak because of close jointing. the product of plucking is bowlders, while the product of abrasion is fine rock flour and sand. is the ground moraine of figure due chiefly to abrasion or to plucking? [illustration: fig. . roches moutonnés, bronx park, new york] =roches moutonnées and rounded hills.= the prominences left between the hollows due to plucking are commonly ground down and rounded on the stoss side,--the side from which the ice advances,--and sometimes on the opposite, the lee side, as well. in this way the bed rock often comes to have a billowy surface known as roches moutonnées (sheep rocks). hills overridden by an ice sheet often have similarly rounded contours on the stoss side, while on the lee side they may be craggy, either because of plucking or because here they have been less worn from their initial profile (fig. ). =the direction of glacier movement.= the direction of the flow of vanished glaciers and ice sheets is recorded both in the differences just mentioned in the profiles of overridden hills and also in the minute details of the glacier trail. flint nodules or other small prominences in the bed rock are found more worn on the stoss than on the lee side, where indeed they may have a low cone of rock protected by them from abrasion. cavities, on the other hand, have their edges worn on the lee side and left sharp upon the stoss. surfaces worn and torn in the ways which we have mentioned are said to be glaciated. but it must not be supposed that a glacier everywhere glaciates its bed. although in places it acts as a rasp or as a pick, in others, and especially where its pressure is least, as near the terminus, it moves over its bed in the manner of a sled. instances are known where glaciers have advanced over deposits of sand and gravel without disturbing them to any notable degree. like a river, a glacier does not everywhere erode. in places it leaves its bed undisturbed and in places aggrades it by deposits of the ground moraine. [illustration: fig. . a glaciated hill, norway. sharp weathered mountain peaks in the distance] =cirques.= valley glaciers commonly head as we have seen, in broad amphitheaters deeply filled with snow and ice. on mountains now destitute of glaciers, but whose glaciation shows that they have supported glaciers in the past, there are found similar crescentic hollows with high, precipitous walls and glaciated floors. their floors are often basined and hold lakelets whose deep and quiet waters reflect the sheltering ramparts of rugged rock which tower far above them. such mountain hollows are termed _cirques_. as a powerful spring wears back a recess in the valley side where it discharges, so the fountain head of a glacier gradually wears back a cirque. in its slow movement the névé field broadly scours its bed to a flat or basined floor. meanwhile the sides of the valley head are steepened and driven back to precipitous walls. for in winter the crevasse of the bergschrund which surrounds the névé field is filled with snow and the névé is frozen fast to the rocky sides of the valley. in early summer the névé tears itself free, dislodging and removing any loosened blocks, and the open fissure of the bergschrund allows frost and other agencies of weathering to attack the unprotected rock. as cirques are thus formed and enlarged the peaks beneath which they lie are sharpened, and the mountain crests are scalloped and cut back from either side to knife-edged ridges (figs. and ). [illustration: fig. . cirques, sierra nevada mountains] in the western mountains of the united states many cirques, now empty of névé and glacier ice, and known locally as "basins," testify to the fact that in recent times the snow line stood beneath the levels of their floors, and thus far below its present altitude. [illustration: fig. . a glacier trough, montana] =glacier troughs.= the channel worn to accommodate the big and clumsy glacier differs markedly from the river valley cut as with a saw by the narrow and flexible stream and widened by the weather and the wash of rains. the valley glacier may easily be from one thousand to three thousand feet deep and from one to three miles wide. such a ponderous bulk of slowly moving ice does not readily adapt itself to sharp turns and a narrow bed. by scouring and plucking all resisting edges it develops a fitting channel with a wide, flat floor, and steep, smooth sides, above which are seen the weathered slopes of stream-worn mountain valleys. since the trunk glacier requires a deeper channel than do its branches, the bed of a branch glacier enters the main trough at some distance above the floor of the latter, although the surface of the two ice streams may be accordant. glacier troughs can be studied best where large glaciers have recently melted completely away, as is the case in many valleys of the mountains of the western united states and of central and northern europe (fig. ). the typical glacier trough, as shown in such examples, is u-shaped, with a broad, flat floor, and high, steep walls. its walls are little broken by projecting spurs and lateral ravines. it is as if a v-valley cut by a river had afterwards been gouged deeper with a gigantic chisel, widening the floor to the width of the chisel blade, cutting back the spurs, and smoothing and steepening the sides. a river valley could only be as wide-floored as this after it had long been worn down to grade. [illustration: fig. lynn canal, alaska, a fjord] but the floor of a glacier trough may not be graded; it is often interrupted by irregular steps perhaps hundreds and even a thousand feet in height, over which the stream that now drains the valley tumbles in waterfalls. reaches between the steps are often basined. lakelets may occupy hollows excavated in solid rock, and other lakes may be held behind terminal moraines left as dams across the valley at pauses in the retreat of the glacier. =fjords= are glacier troughs now occupied in part or wholly by the sea, either because they were excavated by a tide glacier to their present depth below sea level, or because of a submergence of the land. their characteristic form is that of a long, deep, narrow bay with steep rock walls and basined floor (fig. ). fjords are found only in regions which have suffered glaciation, such as norway and alaska. [illustration: fig. . _a_, v-river valley, with valley of tributary joining it a accordant level; _b_, the same changed after long glaciation to a trough with hanging valley] =hanging valleys.= these are lateral valleys which open on their main valley some distance above its floor. they are conspicuous features of glacier troughs from which the ice has vanished; for the trunk glacier in widening and deepening its channel cut its bed below the bottoms of the lateral valleys (fig. ). since the mouths of hanging valleys are suspended on the walls of the glacier trough, their streams are compelled to plunge down its steep, high sides in waterfalls. some of the loftiest and most beautiful waterfalls of the world leap from hanging valleys,--among them the celebrated staubbach of the lauterbrunnen valley of switzerland, and those of the fjords of norway and alaska (fig. ). [illustration: fig. . hanging valley on the wall of a fjord, norway] hanging valleys are found also in river gorges where the smaller tributaries have not been able to keep pace with a strong master stream in cutting down their beds. in this case, however, they are a mark of extreme youth; for, as the trunk stream approaches grade and its velocity and power to erode its bed decrease, the side streams soon cut back their falls and wear their beds at their mouths to a common level with that of the main river. the grand canyon of the colorado must be reckoned a young valley. at its base it narrows to scarcely more than the width of the river, and yet its tributaries, except the very smallest, enter it at a common level. why could not a wide-floored valley, such as a glacier trough, with hanging valleys opening upon it, be produced in the normal development of a river valley? =the troughs of young and of mature glaciers.= the features of a glacier trough depend much on the length of time the preexisting valley was occupied with ice. during the infancy of a glacier, we may believe, the spurs of the valley which it fills are but little blunted and its bed is but little broken by steps. in youth the glacier develops icefalls, as a river in youth develops waterfalls, and its bed becomes terraced with great stairs. the mature glacier, like the mature river, has effaced its falls and smoothed its bed to grade. it has also worn back the projecting spurs of its valley, making itself a wide channel with smooth sides. the bed of a mature glacier may form a long basin, since it abrades most in its upper and middle course, where its weight and motion are the greatest. near the terminus, where weight and motion are the least, it erodes least, and may instead deposit a sheet of ground moraine, much as a river builds a flood plain in the same part of its course as it approaches maturity. the bed of a mature glacier thus tends to take the form of a long, relatively narrow basin, across whose lower end may be stretched the dam of the terminal moraine. on the disappearance of the ice the basin is rilled with a long, narrow lake, such as lake chelan in washington and many of the lakes in the highlands of scotland. piedmont glaciers apparently erode but little. beneath their lake-like expanse of sluggish or stagnant ice a broad sheet of ground moraine is probably being deposited. cirques and glaciated valleys rapidly lose their characteristic forms after the ice has withdrawn. the weather destroys all smoothed, polished, and scored surfaces which are not protected beneath glacial deposits. the over-steepened sides of the trough are graded by landslips, by talus slopes, and by alluvial cones. morainic heaps of drift are dissected and carried away. hanging valleys and the irregular bed of the trough are both worn down to grade by the streams which now occupy them. the length of time since the retreat of the ice from a mountain valley may thus be estimated by the degree to which the destruction of the characteristic features of the glacier trough has been carried. in figure what characteristics of a glacier trough do you notice? what inference do you draw as to the former thickness of the glacier? name all the evidences you would expect to find to prove the fact that in the recent geological past the valleys of the alps contained far larger glaciers than at present, and that on the north of the alps the ice streams united in a piedmont glacier which extended across the plains of switzerland to the sides of the jura mountains. =the relative importance of glaciers and of rivers.= powerful as glaciers are, and marked as are the land forms which they produce, it is easy to exaggerate their geological importance as compared with rivers. under present climatic conditions they are confined to lofty mountains or polar lands. polar ice sheets are permanent only so long as the lands remain on which they rest. mountain glaciers can stay only the brief time during which the ranges continue young and high. as lofty mountains, such as the selkirks and the alps, are lowered by frost and glacier ice, the snowfall will decrease, the line of permanent snow will rise, and as the mountain hollows in which snow may gather are worn beneath the snow line, the glaciers must disappear. under present climatic conditions the work of glaciers is therefore both local and of short duration. [illustration: fig. . longitudinal section of a tide glacier occupying a fjord and discharging icebergs dotted line, sea level] even the glacial epoch, during which vast ice sheets deposited drift over northeastern north america, must have been brief as well as recent, for many lofty mountains, such as the rockies and the alps, still bear the marks of great glaciers which then filled their valleys. had the glacial epoch been long, as the earth counts time, these mountains would have been worn low by ice; had the epoch been remote, the marks of glaciation would already have been largely destroyed by other agencies. on the other hand, rivers are well-nigh universally at work over the land surfaces of the globe, and ever since the dry land appeared they have been constantly engaged in leveling the continents and in delivering to the seas the waste which there is built into the stratified rocks. =icebergs.= tide glaciers, such as those of greenland and alaska, are able to excavate their beds to a considerable distance below sea level. from their fronts the buoyancy of sea water raises and breaks away great masses of ice which float out to sea as icebergs. only about one seventh of a mass of glacier ice floats above the surface, and a berg three hundred feet high may be estimated to have been detached from a glacier not less than two thousand feet thick where it met the sea. icebergs transport on their long journeys whatever drift they may have carried when part of the glacier, and scatter it, as they melt, over the ocean floor. in this way pebbles torn by the inland ice from the rocks of the interior of greenland and glaciated during their carriage in the ground moraine are dropped at last among the oozes of the bottom of the north atlantic. chapter vi the work of the wind [illustration: fig. . a sandy region in a desert, the sahara] we are now to study the geological work of the currents of the atmosphere, and to learn how they erode, and transport and deposit waste as they sweep over the land. illustrations of the wind's work are at hand in dry weather on any windy day. clouds of dust are raised from the street and driven along by the gale. here the roadway is swept bare; and there, in sheltered places, the dust settles in little windrows. the erosive power of waste-laden currents of air is suggested as the sharp grains of flying sand sting one's face or clatter against the window. in the country one sometimes sees the dust whirled in clouds from dry, plowed fields in spring and left in the lee of fences in small drifts resembling in form those of snow in winter. =the essential conditions= for the wind's conspicuous work are illustrated in these simple examples; they are aridity and the absence of vegetation. in humid climates these conditions are only rarely and locally met; for the most part a thick growth of vegetation protects the moist soil from the wind with a cover of leaves and stems and a mattress of interlacing roots. but in arid regions either vegetation is wholly lacking, or scant growths are found huddled in detached clumps, leaving interspaces of unprotected ground (fig. ). here, too, the mantle of waste, which is formed chiefly under the action of temperature changes, remains dry and loose for long periods. little or no moisture is present to cause its particles to cohere, and they are therefore readily lifted and drifted by the wind. transportation by the wind in the desert the finer waste is continually swept to and fro by the ever-shifting wind. even in quiet weather the air heated by contact with the hot sands rises in whirls, and the dust is lifted in stately columns, sometimes as much as one thousand feet in height, which march slowly across the plain. in storms the sand is driven along the ground in a continuous sheet, while the air is tilled with dust. explorers tell of sand storms in the deserts of central asia and africa, in which the air grows murky and suffocating. even at midday it may become dark as night, and nothing can be heard except the roar of the blast and the whir of myriads of grains of sand as they fly past the ear. sand storms are by no means uncommon in the arid regions of the western united states. in a recent year, six were reported from yuma, arizona. trains on transcontinental railways are occasionally blockaded by drifting sand, and the dust sifts into closed passenger coaches, covering the seats and floors. after such a storm thirteen car loads of sand were removed from the platform of a station on a western railway. =dust falls.= dust launched by upward-whirling winds on the swift currents of the upper air is often blown for hundreds of miles beyond the arid region from which it was taken. dust falls from western storms are not unknown even as far east as the great lakes. in a "black snow" fell in chicago, and in another dust storm in the same decade the amount of dust carried in the air over rock island, ill., was estimated at more than one thousand tons to the cubic mile. [illustration: fig. . a tract of rocky desert, arabia by what process have these rocks been broken up? why is finer waste here absent?] in march, , a cyclonic storm carried vast quantities of dust from the sahara northward across the mediterranean to fall over southern and central europe. on march th dust storms raged in southern algeria; two days later the dust fell in italy; and on the th it had reached central germany and denmark. it is estimated that in these few days one million eight hundred thousand tons of waste were carried from northern africa and deposited on european soil. we may see from these examples the importance of the wind as an agent of transportation, and how vast in the aggregate are the loads which it carries. there are striking differences between air and water as carriers of waste. rivers flow in fixed and narrow channels to definite goals. the channelless streams of the air sweep across broad areas, and, shifting about continually, carry their loads back and forth, now in one direction and now in another. wind deposits the mantle of waste of deserts is rapidly sorted by the wind. the coarser rubbish, too heavy to be lifted into the air, is left to strew wide tracts with residual gravels (fig. ). the sand derived from the disintegration of desert rocks gathers in vast fields. about one eighth of the surface of the sahara is said to be thus covered with drifting sand. in desert mountains, as those of sinai, it lies like fields of snow in the high valleys below the sharp peaks. on more level tracts it accumulates in seas of sand, sometimes, as in the deserts of arabia, two hundred and more feet deep. [illustration: fig. . longitudinal dunes, desert of northwestern india scale, in = miles] =dunes.= the sand thus accumulated by the wind is heaped in wavelike hills called dunes. in the desert of northwestern india, where the prevalent wind is of great strength, the sand is laid in longitudinal dunes, i.e. in stripes running parallel with the direction of the wind; but commonly dunes lie, like ripple marks, transverse to the wind current. on the windward side they show a long, gentle slope, up which grains of sand can readily be moved; while to the lee their slope is frequently as great as the angle of repose (fig. ). dunes whose sands are not fixed by vegetation travel slowly with the wind; for their material is ever shifted forward as the grains are driven up the windward slope and, falling over the crest, are deposited in slanting layers in the quiet of the lee. [illustration: fig. . a transverse dune, seven mile beach, new jersey account for the difference of slope in the two sides of the dune. is the dune marching? in what direction? with what effect? do the ridges of the ripple marks upon the dune extend along it or athwart it? why?] like river deposits, wind-blown sands are stratified, since they are laid by currents of air varying in intensity, and therefore in transporting power, which carry now finer and now coarser materials and lay them down where their velocity is checked (fig. ). since the wind varies in direction, the strata dip in various directions. they also dip at various angles, according to the inclination of the surface on which they were laid. [illustration: fig. . stratified wind-blown sands, bermuda islands these islands are made wholly of limestone, the product of reef-building corals, and of lime from the sea water. the limestone sand of the beaches has been blown up into great dunes, some more than two hundred feet in height. much of the loose dune sand has been changed to firm rock by percolating waters, which have dissolved some of the limestone and deposited it again as a cement between the grains] dunes occur not only in arid regions, but also wherever loose sand lies unprotected by vegetation from the wind. from the beaches of sea and lake shores the wind drives inland the surface sand left dry between tides and after storms, piling it in dunes which may invade forests and fields and bury villages beneath their slowly advancing waves. on flood plains during summer droughts river deposits are often worked over by the wind; the sand is heaped in hummocks and much of the fine silt is caught and held by the forests and grassy fields of the bordering hills. [illustration: fig. . cross section of transverse dune after reversal of wind redraw diagram, showing by dotted line the original outline of the dune] the sand of shore dunes differs little in composition and the shape of its grains from that of the beach from which it was derived. but in deserts, by the long wear of grain on grain as they are blown hither and thither by the wind, all soft minerals are ground to powder and the sand comes to consist almost wholly of smooth round grams of hard quartz. [illustration: fig. . dune sands, shore of lake michigan account for the dead forest, for its leaning tree trunks. is the lake shore to the right or left? what has been the history of the landscape?] some marine sandstones, such as the st. peter sandstone of the upper mississippi valley, are composed so entirely of polished spherules of quartz that it has been believed by some that their grains were long blown about in ancient deserts before they were deposited in the sea. [illustration: fig. . crescentic sand dunes, valley of the columbia river did the wind which shaped them blow from the left or from the right?] =dust deposits.= as desert sands are composed almost wholly of quartz, we may ask what has become of the softer minerals of which the rocks whose disintegration has supplied the sand were in part, and often in large part, composed. the softer minerals have been ground to powder, and little by little the quartz sand also is worn by attrition to fine dust. yet dust deposits are scant and few in great deserts such as the sahara. the finer waste is blown beyond its limits and laid in adjacent oceans, where it adds to the muds and oozes of their floors, and on bordering steppes and forest lands, where it is bound fast by vegetation and slowly accumulates in deposits of unstratified loose yellow earth. the fine waste of the sahara has been identified in dredgings from the bottom of the atlantic ocean, taken hundreds of miles from the coast of africa. =loess.= in northern china an area as large as france is deeply covered with a yellow pulverulent earth called loess (german, loose), which many consider a dust deposit blown from the great mongolian desert lying to the west. loess mantles the recently uplifted mountains to the height of eight thousand feet and descends on the plains nearly to sea level. its texture and lack of stratification give it a vertical cleavage; hence it stands in steep cliffs on the sides of the deep and narrow trenches which have been cut in it by streams. on loess hillsides in china are thousands of villages whose eavelike dwellings have been excavated in this soft, yet firm, dry loam. while dust falls are common at the present time in this region, the loess is now being rapidly denuded by streams, and its yellow silt gives name to the muddy hwang-ho (yellow river), and to the yellow sea, whose waters it discolors for scores of miles from shore. wind deposits both of dust and of sand may be expected to contain the remains of land shells, bits of wood, and bones of land animals, testifying to the fact that they were accumulated in open air and not in the sea or in bodies of fresh water. wind erosion [illustration: fig. . wind-carved rocks, arizona] sand-laden currents of air abrade and smooth and polish exposed rock surfaces, acting in much the same way as does the jet of steam fed with sharp sand, which is used in the manufacture of ground glass. indeed, in a single storm at cape cod a plate glass of a lighthouse was so ground by flying sand that its transparency was destroyed and its removal made necessary. [illustration: fig. . a wind-carved pebble, cape cod] telegraph poles and wires whetted by wind-blown sands are destroyed within a few years. in rocks of unequal resistance the harder parts are left in relief, while the softer are etched away. thus in the pass of san bernardino, cal., through which strong winds stream from the west, crystals of garnet are left projecting on delicate rock fingers from the softer rock in which they were imbedded. wind-carved pebbles are characteristically planed, the facets meeting along a summit ridge or at a point like that of a pyramid. we may suppose that these facets were ground by prevalent winds from certain directions, or that from time to time the stone was undermined and rolled over as the sand beneath it was blown away on the windward side, thus exposing fresh surfaces to the driving sand. such wind-carved pebbles are sometimes found in ancient rocks and may be accepted as evidence that the sands of which the rocks are composed were blown about by the wind. =deflation.= in the denudation of an arid region, wind erosion is comparatively ineffective as compared with deflation (latin, _de_, from; _flare_, to blow),--a term by which is meant the constant removal of waste by the wind, leaving the rocks bare to the continuous attack of the weather. in moist climates denudation is continually impeded by the mantle of waste and its cover of vegetation, and the land surface can be lowered no faster than the waste is removed by running water. deep residual soils come to protect all regions of moderate slope, concealing from view the rock structure, and the various forms of the land are due more to the agencies of erosion and transportation than to differences in the resistance of the underlying rocks. [illustration: fig. . mesa verde, colorado in the distance on the left are high volcanic mountains. on the extreme right are seen outliers of strata which once covered the region of the mesa] but in arid regions the mantle is rapidly removed, even from well-nigh level plains and plateaus, by the sweep of the wind and the wash of occasional rains. the geological structure of these regions of naked rock can be read as far as the eye can see, and it is to this structure that the forms of the land are there largely due. in a land mass of horizontal strata, for example, any softer surface rocks wear down to some underlying, resistant stratum, and this for a while forms the surface of a level plateau (fig. ). the edges of the capping layer, together with those of any softer layers beneath it, wear back in steep cliffs, dissected by the valleys of wet-weather streams and often swept bare to the base by the wind. as they are little protected by talus, which commonly is removed about as fast as formed, these escarpments and the walls of the valleys retreat indefinitely, exposing some hard stratum beneath which forms the floor of a widening terrace. the high plateaus of northern arizona and southern utah (fig. ), north of the grand canyon of the colorado river, are composed of stratified rocks more than ten thousand feet thick and of very gentle inclination northward. from the broad plat form in which the canyon has been cut rises a series of gigantic stairs, which are often more than one thousand feet high and a score or more of miles in breadth. the retreating escarpments, the cliffs of the mesas and buttes which they have left behind as outliers, and the walls of the ravines are carved into noble architectural forms--into cathedrals, pyramids, amphitheaters, towers, arches, and colonnades--by the processes of weathering aided by deflation. it is thus by the help of the action of the wind that great plateaus in arid regions are dissected and at last are smoothed away to waterless plains, either composed of naked rock, or strewed with residual gravels, or covered with drifting residual sand. [illustration: fig. . north-south section, eighty-five miles long, across the plateau north of the grand canyon of the colorado river, arizona, showing retreating escarpments _o_, outliers; _v_, canyon of the colorado; _a-h_, rock systems from the archean to the tertiary; _p_, platform of the plateau from which the once overlying rocks have been stripped; dotted lines indicate probable former extension of the strata. how thick is the mass of strata which has been removed from over the platform? has this work been accomplished while the colorado river has been cutting its present canyon?] the specific gravity of air is / that of water. how does this fact affect the weight of the material which each can carry at the same velocity? if the rainfall should lessen in your own state to from five to ten inches a year, what changes would take place in the vegetation of the country? in the soil? in the streams? in the erosion of valleys? in the agencies chiefly at work in denuding the land? in what way can a wind-carved pebble be distinguished from a river-worn pebble? from a glaciated pebble? chapter vii the sea and its shores [illustration: fig. . sea cliff and rock bench cut in chalk, dover, england] we have already seen that the ocean is the goal at which the waste of the land arrives. the mantle of rock waste, creeping down slopes, is washed to the sea by streams, together with the material which the streams have worn from their beds and that dissolved by underground waters. in arid regions the winds sweep waste either into bordering oceans or into more humid regions where rivers take it up and carry it on to the sea. glaciers deliver the load of their moraines either directly to the sea or leave it for streams to transport to the same goal. all deposits made on the land, such as the flood plains of rivers, the silts of lake beds, dune sands, and sheets of glacial drift, mark but pauses in the process which is to bring all the materials of the land now above sea level to rest upon the ocean bed. but the sea is also at work along all its shores as an agent of destruction, and we must first take up its work in erosion before we consider how it transports and deposits the waste of the land. sea erosion =the sea cliff and the rock bench.= on many coasts the land fronts the ocean in a line of cliffs (fig. ). to the edge of the cliffs there lead down valleys and ridges, carved by running water, which, if extended, would meet the water surface some way out from shore. evidently they are now abruptly cut short at the present shore line because the land has been cut back. [illustration: fig. . diagram of sea cliff _sc_, and rock bench _rb_ the broken line indicates the former extent of the land.] along the foot of the cliff lies a gently shelving bench of rock, more or less thickly veneered with sand and shingle. at low tide its inner margin is laid bare, but at high tide it is covered wholly, and the sea washes the base of the cliffs. a notch, of which the _sea cliff_ and the _rock bench_ are the two sides, has been cut along the shore (fig. ). =waves.= the position of the rock bench, with its inner margin slightly above low tide, shows that it has been cut by some agent which acts like a horizontal saw set at about sea level. this agent is clearly the surface agitation of the water; it is the wind-raised wave. as a wave comes up the shelving bench the crest topples forward and the wave "breaks," striking a blow whose force is measured by the momentum of all its tons of falling water (fig. ). on the coast of scotland the force of the blows struck by the waves of the heaviest storms has sometimes exceeded three tons to the square foot. but even a calm sea constantly chafes the shore. it heaves in gentle undulations known as the ground swell, the result of storms perhaps a thousand miles distant, and breaks on the shore in surf. [illustration: fig. . breaking wave, lake superior] the blows of the waves are not struck with clear water only, else they would have little effect on cliffs of solid rock. storm waves arm themselves with the sand and gravel, the cobbles, and even the large bowlders which lie at the base of the cliff, and beat against it with these hammers of stone. where a precipice descends sheer into deep water, waves swash up and down the face of the rocks but cannot break and strike effective blows. they therefore erode but little until the talus fallen from the cliff is gradually built up beneath the sea to the level at which the waves drag bottom upon it and break. compare the ways in which different agents abrade. the wind lightly brushes sand and dust over exposed surfaces of rock. running water sweeps fragments of various sizes along its channels, holding them with a loose hand. glacial ice grinds the stones of its ground moraine against the underlying rock with the pressure of its enormous weight. the wave hurls fragments of rock against the sea cliff, bruising and battering it by the blow. it also rasps the bench as it drags sand and gravel to and fro upon it. =weathering of sea cliffs.= the sea cliff furnishes the weapons for its own destruction. they are broken from it not only by the wave but also by the weather. indeed the sea cliff weathers more rapidly, as a rule, than do rock ledges inland. it is abundantly wet with spray. along its base the ground water of the neighboring land finds its natural outlet in springs which under mine it. moreover, it is unprotected by any shield of talus. fragments of rock as they fall from its face are battered to pieces by the waves and swept out to sea. the cliff is thus left exposed to the attack of the weather, and its retreat would be comparatively rapid for this reason alone. [illustration: fig. . sea caves, la jolla, california copyright, , by the detroit photography company] sea cliffs seldom overhang, but commonly, as in figure , slope seaward, showing that the upper portion has retreated at a more rapid rate than has the base. which do you infer is on the whole the more destructive agent, weathering or the wave? draw a section of a sea cliff cut in well jointed rocks whose joints dip toward the land. draw a diagram of a sea cliff where the joints dip toward the sea. =sea caves.= the wave does not merely batter the face of the cliff. like a skillful quarryman it inserts wedges in all natural fissures, such as joints, and uses explosive forces. as a wave flaps against a crevice it compresses the air within with the sudden stroke; as it falls back the air as suddenly expands. on lighthouses heavily barred doors have been burst outward by the explosive force of the air within, as it was released from pressure when a partial vacuum was formed by the refluence of the wave. where a crevice is filled with water the entire force of the blow of the wave is transmitted by hydraulic pressure to the sides of the fissure. thus storm waves little by little pry and suck the rock loose, and in this way, and by the blows which they strike with the stones of the beach, they quarry out about a joint, or wherever the rock may be weak, a recess known as a _sea cave_, provided that the rock above is coherent enough to form a roof. otherwise an open chasm results. [illustration: fig. . a sea arch, california copyright, , by the detroit photography company] =blowholes and sea arches.= as a sea cave is drilled back into the rock, it may encounter a joint or crevice opened to the surface by percolating water. the shock of the waves soon enlarges this to a blowhole, which one may find on the breezy upland, perhaps a hundred yards and more back from the cliff's edge. in quiet weather the blowhole is a deep well; in storm it plays a fountain as the waves drive through the long tunnel below and spout their spray high in air in successive jets. as the roof of the cave thus breaks down in the rear, there may remain in front for a while a sea arch, similar to the natural bridges of land caverns (fig. ). [illustration: fig. . chasms worn by waves, coast of scotland] =stacks and wave-cut islands.= as the sea drives its tunnels and open drifts into the cliff, it breaks through behind the intervening portions and leaves them isolated as stacks, much as monuments are detached from inland escarpments by the weather; and as the sea cliff retreats, these remnant masses may be left behind as rocky islets. thus the rock bench is often set with stacks, islets in all stages of destruction, and sunken reefs,--all wrecks of the land testifying to its retreat before the incessant attack of the waves. [illustration: fig. . a stack, scotland] [illustration: fig. . wave-cut islands, scotland how far did the land once extend?] =coves.= where zones of soft or closely jointed rock outcrop along a shore, or where minor water courses conic down to the sea and aid in erosion, the shore is worn back in curved reëntrants called coves; while the more resistant rocks on either hand are left projecting as headlands (fig. ). after coves are cut back a short distance by the waves, the headlands come to protect them, as with breakwaters, and prevent their indefinite retreat. the shore takes a curve of equilibrium, along which the hard rock of the exposed headland and the weak rock of the protected cove wear back at an equal rate. [illustration: fig. . coves formed in softer strata _s_, _s_; while the harder strata _h_, _h_, are left as headlands] =rate of recession.= the rate at which a shore recedes depends on several factors. in soft or incoherent rocks exposed to violent storms the retreat is so rapid as to be easily measured. the coast of yorkshire, england, whose cliffs are cut in glacial drift, loses seven feet a year on the average, and since the norman conquest a strip a mile wide, with farmsteads and villages and historic seaports, has been devoured by the sea. the sandy south shore of martha's vineyard wears back three feet a year. but hard rocks retreat so slowly that their recession has seldom been measured by the records of history. [illustration: fig. . a pebble beach, cape ann, massachusetts] shore drift =bowlder and pebble beaches.= about as fast as formed the waste of the sea cliff is swept both along the shore and out to sea. the road of waste along shore is the _beach_. we may also define the beach as the exposed edge of the sheet of sediment formed by the carriage of land waste out to sea. at the foot of sea cliffs, where the waves are pounding hardest, one commonly finds the rock bench strewn on its inner margin with large stones, dislodged by the waves and by the weather and somewhat worn on their corners and edges. from this _bowlder beach_ the smaller fragments of waste from the cliff and the fragments into which the bowlders are at last broken drift on to more sheltered places and there accumulate in a _pebble beach_, made of pebbles well rounded by the wear which they have suffered. such beaches form a mill whose raw material is constantly supplied by the cliff. the breakers of storms set it in motion to a depth of several feet, grinding the pebbles together with a clatter to be heard above the roar of the surf. in such a rock crusher the life of a pebble is short. where ships have stranded on our atlantic coast with cargoes of hard-burned brick or of coal, a year of time and a drift of five miles along the shore have proved enough to wear brick and coal to powder. at no great distance from their source, therefore, pebble beaches give place to beaches of sand, which occupy the more sheltered reaches of the shore. =sand beaches.= the angular sand grains of various minerals into which pebbles are broken by the waves are ground together under the beating surf and rounded, and those of the softer minerals are crushed to powder. the process, however, is a slow one, and if we study these sand grains under a lens we may be surprised to see that, though their corners and edges have been blunted, they are yet far from the spherical form of the pebbles from which they were derived. the grains are small, and in water they have lost about half their weight in air; the blows which they strike one another are therefore weak. besides, each grain of sand of the wet beach is protected by a cushion of water from the blows of its neighbors. the shape and size of these grains and the relative proportion of grains of the softer minerals which still remain give a rough measure of the distance in space and time which they have traveled from their source. the sand of many beaches, derived from the rocks of adjacent cliffs or brought in by torrential streams from neighboring highlands, is dark with grains of a number of minerals softer than quartz. the white sand of other beaches, as those of the east coast of florida, is almost wholly composed of quartz grains; for in its long travel down the atlantic coast the weaker minerals have been worn to powder and the hardest alone survive. how does the absence of cleavage in quartz affect the durability of quartz sand? =how shore drift migrates.= it is under the action of waves and currents that shore drift migrates slowly along a coast. where waves strike a coast obliquely they drive the waste before them little by little along the shore. thus on a north-south coast, where the predominant storms are from the northeast, there will be a migration of shore drift southwards. all shores are swept also by currents produced by winds and tides. these are usually far too gentle to transport of themselves the coarse materials of which beaches are made. but while the wave stirs the grains of sand and gravel, and for a moment lifts them from the bottom, the current carries them a step forward on their way. the current cannot lift and the wave cannot carry, but together the two transport the waste along the shore. the road of shore drift is therefore the zone of the breaking waves. [illustration: fig. . a bay bar, lake ontario] =the bay-head beach.= as the waste derived from the wear of waves and that brought in by streams is trailed along a coast it assumes, under varying conditions, a number of distinct forms. when swept into the head of a sheltered bay it constitutes the bay-head beach. by the highest storm waves the beach is often built higher than the ground immediately behind it, and forms a dam inclosing a shallow pond or marsh. =the bay bar.= as the stream of shore drift reaches the mouth of a bay of some size it often occurs that, instead of turning in, it sets directly across toward the opposite headland. the waste is carried out from shore into the deeper waters of the bay mouth; where it is no longer supported by the breaking waves, and sinks to the bottom. the dump is gradually built to the surface as a stubby spur, pointing across the bay, and as it reaches the zone of wave action current and wave can now combine to carry shore drift along it, depositing their load continually at the point of the spur. an embankment is thus constructed in much the same manner as a railway fill, which, while it is building, serves as a roadway along which the dirt from an adjacent cut is carted to be dumped at the end. when the embankment is completed it bridges the bay with a highway along which shore drift now moves without interruption, and becomes a bay bar. [illustration: fig. . a hook, lake michigan] =incomplete bay bars.= under certain conditions the sea cannot carry out its intention to bridge a bay. rivers discharging in bays demand open way to the ocean. strong tidal currents also are able to keep open channels scoured by their ebb and flow. in such cases the most that land waste can do is to build spits and shoals, narrowing and shoaling the channel as much as possible. incomplete bay bars sometimes have their points recurved by currents setting at right angles to the stream of shore drift and are then classified as _hooks_ (fig. ). [illustration: fig. . cross section of sand reef _sr_, and lagoon; _sl_, sea level] =sand reefs.= on low coasts where shallow water extends some distance out, the highway of shore drift lies along a low, narrow ridge, termed the sand reef, separated from the land by a narrow stretch of shallow water called the _lagoon_ (fig. ). at intervals the reef is held open by _inlets_,--gaps through which the tide flows and ebbs, and by which the water of streams finds way to the sea. [illustration: fig. . sand reef and lagoon, texas] no finer example of this kind of shore line is to be found in the world than the coast of texas. from near the mouth of the rio grande a continuous sand reef draws its even curve for a hundred miles to corpus christi pass, and the reefs are but seldom interrupted by inlets as far north as galveston harbor. on this coast the tides are variable and exceptionally weak, being less than one foot in height, while the amount of waste swept along the shore is large. the lagoon is extremely shallow, and much of it is a mud flat too shoal for even small boats. on the coast of new jersey strong tides are able to keep open inlets at intervals of from two to twenty miles in spite of a heavy alongshore drift. sand reefs are formed where the water is so shallow near shore that storm waves cannot run in it and therefore break some distance out from land. where storm waves first drag bottom they erode and deepen the sea floor, and sweep in sediment as far as the line where they break. here, where they lose their force, they drop their load and beat up the ridge which is known as the sand reef when it reaches the surface. shores of elevation and depression our studies have already brought to our notice two distinct forms of strand lines,--one the high, rocky coast cut back to cliffs by the attack of the waves, and the other the low, sandy coast where the waves break usually upon the sand reef. to understand the origin of these two types we must know that the meeting place of sea and land is determined primarily by movements of the earth's crust. where a coast land emerges the--shore line moves seaward; where it is being submerged the shore line advances on the land. =shores of elevation.= the retreat of the sea, either because of a local uplift of the land or for any other reason, such as the lowering of any portion of ocean bottom, lays bare the inner margin of the sea floor. where the sea floor has long received the waste of the land it has been built up to a smooth, subaqueous plain, gently shelving from the land. since the new shore line is drawn across this even surface it is simple and regular, and is bordered on the one side by shallow water gradually deepening seaward, and on the other by low land composed of material which has not yet thoroughly consolidated to firm rock. a sand reef is soon beaten up by the waves, and for some time conditions will favor its growth. the loss of sand driven into the lagoon beyond, and of that ground to powder by the surf and carried out to sea, is more than made up by the stream of alongshore drift, and especially by the drag of sediments to the reef by the waves as they deepen the sea floor on its seaward side. meanwhile the lagoon gradually fills with waste from the reef and from the land. it is invaded by various grasses and reeds which have learned to grow in salt and brackish water; the marsh, laid bare only at low tide, is built above high tide by wind drift and vegetable deposits, and becomes a meadow, soldering the sand reef to the mainland. while the lagoon has been filling, the waves have been so deepening the sea floor off the sand reef that at last they are able to attack it vigorously. they now wear it back, and, driving the shore line across the lagoon or meadow, cut a line of low cliffs on the mainland. such a shore is that of gascony in southwestern france,--a low, straight, sandy shore, bordered by dunes and unprotected by reefs from the attack of the waves of the bay of biscay. [illustration: fig. . map of new jersey, with that portion of the state one hundred feet and more above sea level shaded describe the coast line which the state would have if depressed one hundred feet. compare it with the present coastline] we may say, then, that on shores of elevation the presence of sand reefs and lagoons indicates the stage of youth, while the absence of these features and the vigorous and unimpeded attack by the sea upon the mainland indicate the stage of maturity. where much waste is brought in by rivers the maturity of such a coast may be long delayed. the waste from the land keeps the sea shallow offshore and constantly renews the sand reef. the energy of the waves is consumed in handling shore drift, and no energy is left for an effective attack upon the land. indeed, with an excessive amount of waste brought down by streams the land may be built out and encroach temporarily upon the sea; and not until long denudation has lowered the land, and thus decreased the amount of waste from it, may the waves be able to cut through the sand reef and thus the coast reach maturity. shores of depression where a coastal region is undergoing submergence the shore line moves landward. the horizontal plane of the sea now intersects an old land surface roughened by subaërial denudation. the shore line is irregular and indented in proportion to the relief of the land and the amount of the submergence which the land has suffered. it follows up partially submerged valleys, forming bays, and bends round the divides, leaving them to project as promontories and peninsulas. the outlines of shores of depression are as varied as are the forms of the land partially submerged. we give a few typical illustrations. [illustration: fig. . chesapeake bay draw a sketch of this area before its depression] the characteristics of the coast of maine are due chiefly to the fact that a mountainous region of hard rocks, once worn to a peneplain, and after a subsequent elevation deeply dissected by north-south valleys, has subsided, the depression amounting on its southern margin to as much as six hundred feet below sea level. drowned valleys penetrate the land in long, narrow bays, and rugged divides project in long, narrow land arms prolonged seaward by islands representing the high portions of their extremities. of this exceedingly ragged shore there are said to be two thousand miles from the new brunswick boundary as far west as portland,--a straight-line distance of but two hundred miles. since the time of its greatest depression the land is known to have risen some three hundred feet; for the bays have been shortened, and the waste with which their floors were strewn is now in part laid bare as clay plains about the bay heads and in narrow selvages about the peninsulas and islands. the coast of dalmatia, on the adriatic sea, is characterized by long land arms and chains of long and narrow islands, all parallel to the trend of the coast. a region of parallel mountain ranges has been depressed, and the longitudinal valleys which lie between them are occupied by arms of the sea. chesapeake bay is a branching bay due to the depression of an ancient coastal plain which, after having emerged from the sea, was channeled with broad, shallow valleys. the sea has invaded the valley of the trunk stream and those of its tributaries, forming a shallow bay whose many branches are all directed toward its axis (fig. ). hudson bay, and the north, the baltic, and the yellow seas are examples where the sinking of the land has brought the sea in over low plains of large extent, thus deeply indenting the continental outline. the rise of a few hundred feet would restore these submerged plains to the land. =the cycle of shores of depression.= in its _infantile stage_ the outline of a shore of depression depends almost wholly on the previous relief of the land, and but little on erosion by the sea. sea cliffs and narrow benches appear where headlands and outlying islands have been nipped by the waves. as yet, little shore waste has been formed. the coast of maine is an example of this stage. in _early youth_ all promontories have been strongly cliffed, and under a vigorous attack of the sea the shore of open bays may be cut back also. sea stacks and rocky islets, caves and coves, make the shore minutely ragged. the irregularity of the coast, due to depression, is for a while increased by differential wave wear on harder and softer rocks. the rock bench is still narrow. shore waste, though being produced in large amounts, is for the most part swept into deeper water and buried out of sight. examples of this stage are the east coast of scotland and the california coast near san francisco. _later youth_ is characterized by a large accumulation of shore waste. the rock bench has been cut back so that it now furnishes a good roadway for shore drift. the stream of alongshore drift grows larger and larger, filling the heads of the smaller bays with beaches, building spits and hooks, and tying islands with sand bars to the mainland. it bridges the larger bays with bay bars, while their length is being reduced as their inclosing promontories are cut back by the waves. thus there comes to be a straight, continuous, and easy road, no longer interrupted by headlands and bays, for the transportation of waste alongshore. the baltic coast of germany is in this stage. [illustration: fig. . portion of the northwest coast of france] all this while streams have been busy filling with delta deposits the bays into which they empty. by these steps a coast gradually advances to _maturity_, the stage when the irregularities due to depression have been effaced, when outlying islands formed by subsidence have been planed away, and when the shore line has been driven back behind the former bay heads. the sea now attacks the land most effectively along a continuous and fairly straight line of cliffs. although the first effect of wave wear was to increase the irregularities of the shore, it sooner or later rectifies it, making it simple and smooth. the northwest coast of france is often cited as an example of a coast which has reached this stage of development (fig. ). in the _old age_ of coasts the rock bench is cut back so far that the waves can no longer exert their full effect upon the shore. their energy is dissipated in moving shore drift hither and thither and in abrading the bench when they drag bottom upon it. little by little the bench is deepened by tidal currents and the drag of waves; but this process is so slow that meanwhile the sea cliffs melt down under the weather, and the bench becomes a broad shoal where waves and tides gradually work over the waste from the land to greater fineness and sweep it out to sea. [illustration: fig. . the south shore of martha's vineyard the land is shaded. to what class of coasts does this belong? what stage has it reached, and by what process? what changes will take place in the future?] =plains of marine abrasion.= while subaërial denudation reduces the land to baselevel, the sea is sawing its edges to _wave base_, i.e. the lowest limit of the wave's effective wear. the widened rock bench forms when uplifted a plain of marine abrasion, which like the peneplain bevels across strata regardless of their various inclinations and various degrees of hardness. how may a plain of marine abrasion be expected to differ from a peneplain in its mantle of waste? compared with subaërial denudation, marine abrasion is a comparatively feeble agent. at the rate of five feet per century--a higher rate than obtains on the youthful rocky, coast of britain--it would require more than ten million years to pare a strip one hundred miles wide from the margin of a continent, a time sufficient, at the rate at which the mississippi valley is now being worn away, for subaërial denudation to lower the lands of the globe to the level of the sea. slow submergence favors the cutting of a wide rock bench. the water continually deepens upon the bench; storm waves can therefore always ride in to the base of the cliffs and attack them with full force; shore waste cannot impede the onset of the waves, for it is continually washed out in deeper water below wave base. =basal conglomerates.= as the sea marches across the land during a slow submergence, the platform is covered with sheets of sea-laid sediments. lowest of these is a conglomerate,--the bowlder and pebble beach, widened indefinitely by the retreat of the cliffs at whose base it was formed, and preserved by the finer deposits laid upon it in the constantly deepening water as the land subsides. such basal conglomerates are not uncommon among the ancient rocks of the land, and we may know them by their rounded pebbles and larger stones, composed of the same kind of rock as that of the abraded and evened surface on which they lie. chapter viii offshore and deep-sea deposits the alongshore deposits which we have now studied are the exposed edge of a vast subaqueous sheet of waste which borders the continents and extends often for as much as two or three hundred miles from land. soundings show that offshore deposits are laid in belts parallel to the coast, the coarsest materials lying nearest to the land and the finest farthest out. the pebbles and gravel and the clean, coarse sand of beaches give place to broad stretches of sand, which grows finer and finer until it is succeeded by sheets of mud. clearly there is an offshore movement of waste by which it is sorted, the coarser being sooner dropped and the finer being carried farther out. offshore deposits the debris torn by waves from rocky shores is far less in amount than the waste of the land brought down to the sea by rivers, being only one thirty-third as great, according to a conservative estimate. both mingle alongshore in all the forms of beach and bar that have been described, and both are together slowly carried out to sea. on the shelving ocean floor waste is agitated by various movements of the unquiet water,--by the undertow (an outward-running bottom current near the shore), by the ebb and flow of tides, by ocean currents where they approach the land, and by waves and ground swells, whose effects are sometimes felt to a depth of six hundred feet. by all these means the waste is slowly washed to and fro, and as it is thus ground finer and finer and its soluble parts are more and more dissolved, it drifts farther and farther out from land. it is by no steady and rapid movement that waste is swept from the shore to its final resting place. day after day and century after century the grains of sand and particles of mud are shifted to and fro, winnowed and spread in layers, which are destroyed and rebuilt again and again before they are buried safe from further disturbance. these processes which are hidden from the eye are among the most important of those with which our science has to do; for it is they which have given shape to by far the largest part of the stratified rocks of which the land is made. =the continental delta.= this fitting term has been recently suggested for the sheet of waste slowly accumulating along the borders of the continents. within a narrow belt, which rarely exceeds two or three hundred miles, except near the mouths of muddy rivers such as the amazon and congo, nearly all the waste of the continent, whether worn from its surface by the weather, by streams, by glaciers, or by the wind, or from its edge by the chafing of the waves, comes at last to its final resting place. the agencies which spread the material of the continental delta grow more and more feeble as they pass into deeper and more quiet water away from shore. coarse materials are therefore soon dropped along narrow belts near land. gravels and coarse sands lie in thick, wedge-shaped masses which thin out seaward rapidly and give place to sheets of finer sand. =sea muds.= outermost of the sediments derived from the waste of the continents is a wide belt of mud; for fine clays settle so slowly, even in sea water,--whose saltness causes them to sink much faster than they would in fresh water,--that they are wafted far before they reach a bottom where they may remain undisturbed. muds are also found near shore, carpeting the floors of estuaries, and among stretches of sandy deposits in hollows where the more quiet water has permitted the finer silt to rest. sea muds are commonly bluish and consolidate to bluish shales; the red coloring matter brought from land waste--iron oxide--is altered to other iron compounds by decomposing organic matter in the presence of sea water. yellow and red muds occur where the amount of iron oxide in the silt brought down to the sea by rivers is too great to be reduced, or decomposed, by the organic matter present. green muds and green sand owe their color to certain chemical changes which take place where waste from the land accumulates on the sea floor with extreme slowness. a greenish mineral called _glauconite_--a silicate of iron and alumina--is then formed. such deposits, known as _green sand_, are now in process of making in several patches off the atlantic coast, and are found on the coastal plain of new jersey among the offshore deposits of earlier geological ages. =organic deposits.= living creatures swarm along the shore and on the shallows out from land as nowhere else in the ocean. seaweed often mantles the rock of the sea cliff between the levels of high and low tide, protecting it to some degree from the blows of waves. on the rock bench each little pool left by the ebbing tide is an aquarium abounding in the lowly forms of marine life. below low-tide level occur beds of molluscous shells, such as the oyster, with countless numbers of other humble organisms. their harder parts--the shells of mollusks, the white framework of corals, the carapaces of crabs and other crustaceans, the shells of sea urchins, the bones and teeth of fishes--are gradually buried within the accumulating sheets of sediment, either whole or, far more often, broken into fragments by the waves. by means of these organic remains each layer of beach deposits and those of the continental delta may contain a record of the life of the time when it was laid. such a record has been made ever since living creatures with hard parts appeared upon the globe. we shall find it sealed away in the stratified rocks of the continents,--parts of ancient sea deposits now raised to form the dry land. thus we have in the traces of living creatures found in the rocks, i.e. in fossils, a history of the progress of life upon the planet. [illustration: fig. . coquina, florida] =molluscous shell deposits.= the forms of marine life of importance in rock making thrive best in clear water, where little sediment is being laid, and where at the same time the depth is not so great as to deprive them of needed light, heat, and of sufficient oxygen absorbed by sea water from the air. in such clear and comparatively shallow water there often grow countless myriads of animals, such as mollusks and corals, whose shells and skeletons of carbonate of lime gradually accumulate in beds of limestone. a shell limestone made of broken fragments cemented together is sometimes called _coquina_, a local term applied to such beds recently uplifted from the sea along the coast of florida (fig. ). _oölitic_ limestone (_öon_, an egg; _lithos_, a stone) is so named from the likeness of the tiny spherules which compose it to the roe of fish. corals and shells have been pounded by the waves to calcareous sand, and each grain has been covered with successive concentric coatings of lime carbonate deposited about it from solution. the impalpable powder to which calcareous sand is ground by the waves settles at some distance from shore in deeper and quieter water as a limy silt, and hardens into a dense, fine-grained limestone in which perhaps no trace of fossil is found to suggest the fact that it is of organic origin. from florida keys there extends south to the trough of florida straits a limestone bank covered by from five hundred and forty to eighteen hundred feet of water. the rocky bottom consists of limestone now slowly building from the accumulation of the remains of mollusks, small corals, sea urchins, worms with calcareous tubes, and lime-secreting seaweed, which live upon its surface. where sponges and other silica-secreting organisms abound on limestone banks, silica forms part of the accumulated deposit, either in its original condition, as, for example, the spicules of sponges, or gathered into concretions and layers of flint. where considerable mud is being deposited along with carbonate of lime there is in process of making a clayey limestone or a limy shale; where considerable sand, a sandy limestone or a limy sandstone. =consolidation of offshore deposits.= we cannot doubt that all these loose sediments of the sea floor are being slowly consolidated to solid rock. they are soaked with water which carries in solution lime carbonate and other cementing substances. these cements are deposited between the fragments of shells and corals, the grains of sand and the particles of mud, binding them together into firm rock. where sediments have accumulated to great thickness the lower portions tend also to consolidate under the weight of the overlying beds. except in the case of limestones, recent sea deposits uplifted to form land are seldom so well cemented as are the older strata, which have long been acted upon by underground waters deep below the surface within the zone of cementation, and have been exposed to view by great erosion. [illustration: fig. . ripple marks on layers of ancient sandstone, wisconsin] =ripple marks, sun cracks, etc.= the pulse of waves and tidal currents agitates the loose material of offshore deposits, throwing it into fine parallel ridges called ripple marks. one may see this beautiful ribbing imprinted on beach sands uncovered by the outgoing tide, and it is also produced where the water is of considerable depth. while the tide is out the surface of shore deposits may be marked by the footprints of birds and other animals, or by the raindrops of a passing shower (fig. ). the mud of flats, thus exposed to the sun and dried, cracks in a characteristic way (figs. and ). such markings may be covered over with a thin layer of sediment at the next flood tide and sealed away as a lasting record of the manner and place in which the strata were laid. in figure we have an illustration of a very ancient ripple-marked sand consolidated to hard stone, uplifted and set on edge by movements of the earth's crust, and exposed to open air after long erosion. [illustration: fig. . sun cracks] =stratification.= for the most part the sheet of sea-laid waste is hidden from our sight. where its edge is exposed along the shore we may see the surface markings which have just been noticed. soundings also, and the observations made in shallow waters by divers, tell something of its surface; but to learn more of its structures we must study those ancient sediments which have been lifted from the sea and dissected by subaërial agencies. from them we ascertain that sea deposits are stratified. they lie in distinct layers which often differ from one another in thickness, in size of particles, and perhaps in color. they are parted by bedding planes, each of which represents either a change in material or a pause during which deposition ceased and the material of one layer had time to settle and become somewhat consolidated before the material of the next was laid upon it. stratification is thus due to intermittently acting forces, such as the agitation of the water during storms, the flow and ebb of the tide, and the shifting channels of tidal currents. off the mouths of rivers, stratification is also caused by the coarser and more abundant material brought down at time of floods being laid on the finer silt which is discharged during ordinary stages. [illustration: fig. . the under side of a layer deposited upon a sun-cracked surface, showing casts of the cracks] [illustration: fig. . rain prints] how stratified deposits are built up is well illustrated in the flats which border estuaries, such as the bay of fundy. each advance of the tide spreads a film of mud, which dries and hardens in the air during low water before another film is laid upon it by the next incoming tidal flood. in this way the flats have been covered by a clay which splits into leaves as thin as sheets of paper. it is in fine material, such as clays and shales and limestones, that the thinnest and most uniform layers, as well as those of widest extent, occur. on the other hand, coarse materials are commonly laid in thick beds, which soon thin out seaward and give place to deposits of finer stuff. in a general way strata are laid in well-nigh horizontal sheets, for the surface on which they are laid is generally of very gentle inclination. each stratum, however, is lenticular, or lenslike, in form, having an area where it is thickest, and thinning out thence to its edges, where it is overlapped by strata similar in shape. [illustration: fig. . cross bedding in sandstone, england] =cross bedding.= there is an apparent exception to this rule where strata whose upper and lower surfaces may be about horizontal are made up of layers inclined at angles which may be as high as the angle of repose. in this case each stratum grew by the addition along its edge of successive layers of sediment, precisely as does a sand bar in a river, the sand being pushed continuously over the edge and coming to rest on a sloping surface. shoals built by strong and shifting tidal currents often show successive strata in which the cross bedding is inclined in different directions. =thickness of sea deposits.= remembering the vast amount of material denuded from the land and deposited offshore, we should expect that with the lapse of time sea deposits would have grown to an enormous thickness. it is a suggestive fact that, as a rule, the profile of the ocean bed is that of a soup plate,--a basin surrounded by a flaring rim. on the _continental shelf_, as the rim is called, the water is seldom more than six hundred feet in depth at the outer edge, and shallows gradually towards shore. along the eastern coast of the united states the continental shelf is from fifty to one hundred and more miles in width; on the pacific coast it is much narrower. so far as it is due to upbuilding, a wide continental shelf, such as that of the atlantic coast, implies a massive continental delta thousands of feet in thickness. the coastal plain of the atlantic states may be regarded as the emerged inner margin of this shelf, and borings made along the coast probe it to the depth of as much as three thousand feet without finding the bottom of ancient offshore deposits. continental shelves may also be due in part to a submergence of the outer margin of a continental plateau and to marine abrasion. =deposition of sediments and subsidence.= the stratified rocks of the land show in many places ancient sediments which reach a thickness which is measured in miles, and which are yet the product of well-nigh continuous deposition. such strata may prove by their fossils and by their composition and structure that they were all laid offshore in shallow water. we must infer that, during the vast length of time recorded by the enormous pile, the floor of the sea along the coast was slowly sinking, and that the trough was constantly being filled, foot by foot, as fast as it was depressed. such gradual, quiet movements of the earth's crust not only modify the outline of coasts, as we have seen, but are of far greater geological importance in that they permit the making of immense deposits of stratified rock. a slow subsidence continued during long time is recorded also in the succession of the various kinds of rock that come to be deposited in the same area. as the sea transgresses the land, i.e. encroaches upon it, any given part of the sea bottom is brought farther and farther from the shore. the basal conglomerate formed by bowlder and pebble beaches comes to be covered with sheets of sand, and these with layers of mud as the sea becomes deeper and the shore more remote; while deposits of limestone are made when at last no waste is brought to the place from the now distant land, and the water is left clear for the growth of mollusks and other lime-secreting organisms. [illustration: fig. . succession of deposits recording a transgressing sea _c_, conglomerate; _ss_, sandstone; _sh_, shale; _lm_, limestone] =rate of deposition.= as deposition in the sea corresponds to denudation on the land, we are able to make a general estimate of the rate at which the former process is going on. leaving out of account the soluble matter removed, the mississippi is lowering its basin at the rate of one foot in five thousand years, and we may assume this as the average rate at which the earth's land surface of fifty-seven million square miles is now being denuded by the removal of its mechanical waste. but sediments from the land are spread within a zone but two or three hundred miles in width along the margin of the continents, a line one hundred thousand miles long. as the area of deposition--about twenty-five million square miles--is about one half the area of denudation, the average rate of deposition must be twice the average rate of denudation, i.e. about one foot in twenty-five hundred years. if some deposits are made much more rapidly than this, others are made much more slowly. if they were laid no faster than the present average rate, the strata of ancient sea deposits exposed in a quarry fifty feet deep represent a lapse of at least one hundred and twenty-five thousand years, and those of a formation five hundred feet thick required for their accumulation one million two hundred and fifty thousand years. [illustration: fig. . thick offshore deposits of coarse waste recording the presence of a young mountain range near shore] =the sedimentary record and the denudation cycle.= we have seen that the successive stages in a cycle of denudation, such as that by which a land mass of lofty mountains is worn to low plains, are marked each by its own peculiar land forms, and that the forms of the earlier stages are more or less completely effaced as the cycle draws toward an end. far more lasting records of each stage are left in the sedimentary deposits of the continental delta. thus, in the youth of such a land mass as we have mentioned, torrential streams flowing down the steep mountain sides deliver to the adjacent sea their heavy loads of coarse waste, and thick offshore deposits of sand and gravel (fig. ) record the high elevation of the bordering land. as the land is worn to lower levels, the amount and coarseness of the waste brought to the sea diminishes, until the sluggish streams carry only a fine silt which settles on the ocean floor near to land in wide sheets of mud which harden into shale. at last, in the old age of the region (fig. ), its low plains contribute little to the sea except the soluble elements of the rocks, and in the clear waters near the land lime-secreting organisms flourish and their remains accumulate in beds of limestone. when long-weathered lands mantled with deep, well-oxidized waste are uplifted by a gradual movement of the earth's crust, and the mantle is rapidly stripped off by the revived streams, the uprise is recorded in wide deposits of red and yellow clays and sands upon the adjacent ocean floor. where the waste brought in is more than the waves can easily distribute, as off the mouths of turbid rivers which drain highlands near the sea, deposits are little winnowed, and are laid in rapidly alternating, shaly sandstones and sandy shales. [illustration: fig. . offshore deposits recording old age of the adjacent land _ss_, sandstone; _sh_, shale; _lm_, limestone] where the highlands are of igneous rock, such as granite, and mechanical disintegration is going on more rapidly than chemical decay, these conditions are recorded in the nature of the deposits laid offshore. the waste swept in by streams contains much feldspar and other minerals softer and more soluble than quartz, and where the waves have little opportunity to wear and winnow it, it comes to rest in beds of sandstone in which grains of feldspar and other soft minerals are abundant. such feldspathic sandstones are known as _arkose_. on the other hand, where the waste supplied to the sea comes chiefly from wide, sandy, coastal plains, there are deposited offshore clean sandstones of well-worn grains of quartz alone. in such coastal plains the waste of the land is stored for ages. again and again they are abandoned and invaded by the sea as from time to time the land slowly emerges and is again submerged. their deposits are long exposed to the weather, and sorted over by the streams, and winnowed and worked over again and again by the waves. in the course of long ages such deposits thus become thoroughly sorted, and the grains of all minerals softer than quartz are ground to mud. [illustration: fig. . globigerina ooze under the microscope] deep-sea oozes and clays =globigerina ooze.= beyond the reach of waste from the land the bottom of the deep sea is carpeted for the most part with either chalky ooze or a fine red clay. the surface waters of the warm seas swarm with minute and lowly animals belonging to the order of the _foraminifera_, which secrete shells of carbonate of lime. at death these tiny white shells fall through the sea water like snowflakes in the air, and, slowly dissolving, seem to melt quite away before they can reach depths greater than about three miles. near shore they reach bottom, but are masked by the rapid deposit of waste derived from the land. at intermediate depths they mantle the ocean floor with a white, soft lime deposit known as _globigerina ooze_, from a genus of the foraminifera which contributes largely to its formation. =red clay.= below depths of from fifteen to eighteen thousand feet the ocean bottom is sheeted with red or chocolate colored clay. it is the insoluble residue of seashells, of the debris of submarine volcanic eruptions, of volcanic dust wafted by the winds, and of pieces of pumice drifted by ocean currents far from the volcanoes from which they were hurled. the red clay builds up with such inconceivable slowness that the teeth of sharks and the hard ear bones of whales may be dredged in large numbers from the deep ocean bed, where they have lain unburied for thousands of years; and an appreciable part of the clay is also formed by the dust of meteorites consumed in the atmosphere,--a dust which falls everywhere on sea and land, but which elsewhere is wholly masked by other deposits. the dark, cold abysses of the ocean are far less affected by change than any other portion of the surface of the lithosphere. these vast, silent plains of ooze lie far below the reach of storms. they know no succession of summer and winter, or of night and day. a mantle of deep and quiet water protects them from the agents of erosion which continually attack, furrow, and destroy the surface of the land. while the land is the area of erosion, the sea is the area of deposition. the sheets of sediment which are slowly spread there tend to efface any inequalities, and to form a smooth and featureless subaqueous plain. with few exceptions, the stratified rocks of the land are proved by their fossils and composition to have been laid in the sea; but in the same way they are proved to be offshore, shallow-water deposits, akin to those now making on continental shelves. deep-sea deposits are absent from the rocks of the land, and we may therefore infer that the deep sea has never held sway where the continents now are,--that the continents have ever been, as now, the elevated portions of the lithosphere, and that the deep seas of the present have ever been its most depressed portions. the reef-building corals in warm seas the most conspicuous of rock-making organisms are the corals known as the reef builders. floating in a boat over a coral reef, as, for example, off the south coast of florida or among the bahamas, one looks down through clear water on thickets of branching coral shrubs perhaps as much as eight feet high, and hemispherical masses three or four feet thick, all abloom with countless minute flowerlike coral polyps, gorgeous in their colors of yellow, orange, green, and red. in structure each tiny polyp is little more than a fleshy sac whose mouth is surrounded with petal-like tentacles, or feelers. from the sea water the polyps secrete calcium carbonate and build it up into the stony framework which supports their colonies. boring mollusks, worms, and sponges perforate and honeycomb this framework even while its surface is covered with myriads of living polyps. it is thus easily broken by the waves, and white fragments of coral trees strew the ground beneath. brilliantly colored fishes live in these coral groves, and countless mollusks, sea urchins, and other forms of marine life make here their home. with the debris from all these sources the reef is constantly built up until it rises to low-tide level. higher than this the corals cannot grow, since they are killed by a few hours' exposure to the air. [illustration: fig. . patch of growing corals exposed at an exceptionally low tide, great barrier reef, australia] when the reef has risen to wave base, the waves abrade it on the windward side and pile to leeward coral blocks torn from their foundation, filling the interstices with finer fragments. thus they heap up along the reef low, narrow islands (fig. ). reef building is a comparatively rapid progress. it has been estimated that off florida a reef could be built up to the surface from a depth of fifty feet in about fifteen hundred years. [illustration: fig. . wave-built island on coral reef _r_, reef; _sl_, sea level] =coral limestones.= limestones of various kinds are due to the reef builders. the reef rock is made of corals in place and broken fragments of all sizes, cemented together with calcium carbonate from solution by infiltrating waters. on the island beaches coral sand is forming oolitic limestone, and the white coral mud with which the sea is milky for miles about the reef in times of storm settles and concretes into a compact limestone of finest grain. corals have been among the most important limestone builders of the sea ever since they made their appearance in the early geological ages. the areas on which coral limestone is now forming are large. the great barrier reef of australia, which lies off the northeastern coast, is twelve hundred and fifty miles long, and has a width of from ten to ninety miles. most of the islands of the tropics are either skirted with coral reefs or are themselves of coral formation. =conditions of coral growth.= reef-building corals cannot live except in clear salt water less, as a rule, than one hundred and fifty feet in depth, with a winter temperature not lower than ° f. an important condition also is an abundant food supply, and this is best secured in the path of the warm oceanic currents. coral reefs may be grouped in three classes,--fringing reefs, barrier reefs, and atolls. =fringing reefs.= these take their name from the fact that they are attached as narrow fringes to the shore. an example is the reef which forms a selvage about a mile wide along the northeastern coast of cuba. the outer margin, indicated by the line of white surf, where the corals are in vigorous growth, rises from about forty feet of water. between this and the shore lies a stretch of shoal across which one can wade at low water, composed of coral sand with here and there a clump of growing coral. =barrier reefs.= reefs separated from the shore by a ship channel of quiet water, often several miles in width and sometimes as much as three hundred feet in depth, are known as barrier reefs. the seaward face rises abruptly from water too deep for coral growth. low islands are cast up by the waves upon the reef, and inlets give place for the ebb and flow of the tides. along the west coast of the island of new caledonia a barrier reef extends for four hundred miles, and for a length of many leagues seldom approaches within eight miles of the shore. =atolls.= these are ring-shaped or irregular coral islands, or island-studded reefs, inclosing a central lagoon. the narrow zone of land, like the rim of a great bowl sunken to the water's edge, rises hardly more than twenty feet at most above the sea, and is covered with a forest of trees such as the cocoanut, whose seeds can be drifted to it uninjured from long distances. the white beach of coral sand leads down to the growing reef, on whose outer margin the surf is constantly breaking. the sea face of the reef falls off abruptly, often to depths of thousands of feet, while the lagoon varies in depth from a few feet to one hundred and fifty or two hundred, and exceptionally measures as much as three hundred and fifty feet. =theories of coral reefs.= fringing reefs require no explanation, since the depth of water about them is not greater than that at which coral can grow; but barrier reefs and atolls, which may rise from depths too great for coral growth demand a theory of their origin. [illustration: fig. . diagram illustrating the subsidence theory of coral reefs] darwin's theory holds that barrier reefs and atolls are formed from fringing reefs by _subsidence_. the rate of sinking cannot be greater than that of the upbuilding of the reef, since otherwise the corals would be carried below their depth and drowned. the process is illustrated in figure , where v represents a volcanic island in mid ocean undergoing slow depression, and _ss_ the sea level before the sinking began, when the island was surrounded by a fringing reef. as the island slowly sinks, the reef builds up with equal pace. it rears its seaward face more steep than the island slope, and thus the intervening space between the sinking, narrowing land and the outer margin of the reef constantly widens. in this intervening space the corals are more or less smothered with silt from the outer reef and from the land, and are also deprived in large measure of the needful supply of food and oxygen by the vigorous growth of the corals on the outer rim. the outer rim thus becomes a barrier reef and the inner belt of retarded growth is deepened by subsidence to a ship channel, _s´s´_ representing sea level at this time. the final stage, where the island has been carried completely beneath the sea and overgrown by the contracting reef, whose outer ring now forms an atoll, is represented by _s´´s´´_. [illustration: fig. . barrier reef formed without subsidence _a_, zone of coral growth; _f_, former fringing reef; _t_, talus; _b_, barrier reef] in very many instances, however, atolls and barrier reefs may be explained without subsidence. thus a barrier reef may be formed by the seaward growth of a fringing reef upon the talus of its sea face. in figure , _f_ is a fringing reef whose outer wall rises from about one hundred and fifty feet, the lower limit of the reef-building species. at the foot of this submarine cliff a talus of fallen blocks t accumulates, and as it reaches the zone of coral growth becomes the foundation on which the reef is steadily extended seaward. as the reef widens, the polyps of the circumference flourish, while those of the inner belt are retarded in their growth and at last perish. the coral rock of the inner belt is now dissolved by sea water and scoured out by tidal currents until it gives place to a gradually deepening ship channel, while the outer margin is left as a barrier reef. [illustration: fig. . section of atoll on a shoal which has been built up to near the surface by organic deposits upon a submarine volcanic peak _v_, volcano; _f_, foraminiferal deposits; _m_, molluscous shell deposits; _c_, coral reef; _sl_, sea level] in much the same way atolls may be built on any shoal which lies within the zone of coral growth. such shoals may be produced when volcanic islands are leveled by waves and ocean currents, and when submarine plateaus, ridges, and peaks are built up by various organic agencies, such as molluscous and foraminiferal shell deposits (fig. ). the reef-building corals, whose eggs are drifted widely over the tropic seas by ocean currents, colonize such submarine foundations wherever the conditions are favorable for their growth. as the reef approaches the surface the corals of the inner area are smothered by silt and starved, and their submarine volcanic peak hard parts are dissolved and scoured away; while those of the circumference, with abundant food supply, nourish and build the ring of the atoll. atolls may be produced also by the backward drift of sand from either end of a crescentic coral reef or island, the spits uniting in the quiet water of the lee to inclose a lagoon. in the maldive archipelago all gradations between crescent-shaped islets and complete atoll rings have been observed. in a number of instances where coral reefs have been raised by movements of the earth's crust, the reef formation is found to be a thin veneer built upon a foundation of other deposits. thus christmas island, in the indian ocean, is a volcanic pile rising eleven hundred feet above sea level and fifteen thousand five hundred feet above the bottom of the sea. the summit is a plateau surrounded by a rim of hills of reef formation, which represent the ring of islets of an ancient atoll. beneath the reef are thick beds of limestone, composed largely of the remains of foraminifers, which cover the lavas and fragmental materials of the old submarine volcano. among the ancient sediments which now form the stratified rocks of the land there occur many thin reef deposits, but none are known of the immense thickness which modern reefs are supposed to reach according to the theory of subsidence. barrier and fringing reefs are commonly interrupted off the mouths of rivers. why? =summary.= we have seen that the ocean bed is the goal to which the waste of the rocks of the land at last arrives. their soluble parts, dissolved by underground waters and carried to the sea by rivers, are largely built up by living creatures into vast sheets of limestone. the less soluble portions--the waste brought in by streams and the waste of the shore--form the muds and sands of continental deltas. all of these sea deposits consolidate and harden, and the coherent rocks of the land are thus reconstructed on the ocean floor. but the destination is not a final one. the stratified rocks of the land are for the most part ancient deposits of the sea, which have been lifted above sea level; and we may believe that the sediments now being laid offshore are the "dust of continents to be," and will some time emerge to form additions to the land. we are now to study the movements of the earth's crust which restore the sediments of the sea to the light of day, and to whose beneficence we owe the habitable lands of the present. part ii internal geological agencies chapter ix movements of the earth's crust the geological agencies which we have so far studied--weathering, streams, underground waters, glaciers, winds, and the ocean--all work upon the earth from without, and all are set in motion by an energy external to the earth, namely, the radiant energy of the sun. all, too, have a common tendency to reduce the inequalities of the earth's surface by leveling the lands and strewing their waste beneath the sea. but despite the unceasing efforts of these external agencies, they have not destroyed the continents, which still rear their broad plains and great plateaus and mountain ranges above the sea. either, then, the earth is very young and the agents of denudation have not yet had time to do their work, or they have been opposed successfully by other forces. we enter now upon a department of our science which treats of forces which work upon the earth from within, and increase the inequalities of its surface. it is they which uplift and recreate the lands which the agents of denudation are continually destroying; it is they which deepen the ocean bed and thus withdraw its waters from the shores. at times also these forces have aided in the destruction of the lands by gradually lowering them and bringing in the sea. under the action of forces resident within the earth the crust slowly rises or sinks; from time to time it has been folded and broken; while vast quantities of molten rock have been pressed up into it from beneath and outpoured upon its surface. we shall take up these phenomena in the following chapters, which treat of upheavals and depressions of the crust, foldings and fractures of the crust, earthquakes, volcanoes, the interior conditions of the earth, mineral veins, and metamorphism. oscillations of the crust of the various movements of the crust due to internal agencies we will consider first those called oscillations, which lift or depress large areas so slowly that a long time is needed to produce perceptible changes of level, and which leave the strata in nearly their original horizontal attitude. these movements are most conspicuous along coasts, where they can be referred to the datum plane of sea level; we will therefore take our first illustrations from rising and sinking shores. =new jersey.= along the coasts of new jersey one may find awash at high tide ancient shell heaps, the remains of tribal feasts of aborigines. meadows and old forest grounds, with the stumps still standing, are now overflowed by the sea, and fragments of their turf and wood are brought to shore by waves. assuming that the sea level remains constant, it is clear that the new jersey coast is now gradually sinking. the rate of submergence has been estimated at about two feet per century. on the other hand, the wide coastal plain of new jersey is made of stratified sands and clays, which, as their marine fossils show, were outspread beneath the sea. their present position above sea level proves that the land now subsiding emerged in the recent past. the coast of new jersey is an example of the slow and tranquil oscillations of the earth's unstable crust now in progress along many shores. some are emerging from the sea, some are sinking beneath it; and no part of the land seems to have been exempt from these changes in the past. =evidences of changes of level.= taking the surface of the sea as a level of reference, we may accept as proofs of relative upheaval whatever is now found in place above sea level and could have been formed only at or beneath it, and as proofs of relative subsidence whatever is now found beneath the sea and could only have been formed above it. thus old strand lines with sea cliffs, wave-cut rock benches, and beaches of wave-worn pebbles or sand, are striking proofs of recent emergence to the amount of their present height above tide. no less conclusive is the presence of sea-laid rocks which we may find in the neighboring quarry or outcrop, although it may have been long ages since they were lifted from the sea to form part of the dry land. among common proofs of subsidence are roads and buildings and other works of man, and vegetal growths and deposits, such as forest grounds and peat beds, now submerged beneath the sea. in the deltas of many large rivers, such as the po, the nile, the ganges, and the mississippi, buried soils prove subsidences of hundreds of feet; and in several cases, as in the mississippi delta, the depression seems to be now in progress. other proofs of the same movement are drowned land forms which are modeled only in open air. since rivers cannot cut their valleys farther below the baselevel of the sea than the depths of their channels, _drowned valleys_ are among the plainest proofs of depression. to this class belong narragansett, delaware, chesapeake, mobile, and san francisco bays, and many other similar drowned valleys along the coasts of the united states. less conspicuous are the _submarine channels_ which, as soundings show, extend from the mouths of a number of rivers some distance out to sea. such is the submerged channel which reaches from new york bay southeast to the edge of the continental shelf, and which is supposed to have been cut by the hudson river when this part of the shelf was a coastal plain. =warping.= in a region undergoing changes of level the rate of movement commonly varies in different parts. portions of an area may be rising or sinking, while adjacent portions are stationary or moving in the opposite direction. in this way a land surface becomes _warped_. thus, while nova scotia and new brunswick are now rising from the level of the sea, prince edward island and cape breton island are sinking, and the sea now flows over the site of the famous old town of louisburg destroyed in . since the close of the glacial epoch the coasts of newfoundland and labrador have risen hundreds of feet, but the rate of emergence has not been uniform. the old strand line, which stands at five hundred and seventy-five feet above tide at st. john's, newfoundland, declines to two hundred and fifty feet near the northern point of labrador (fig. ). [illustration: fig. . warped strand line from st. john's, newfoundland, to nachvak, labrador] =the great lakes= is now undergoing perceptible warping. rivers enter the lakes from the south and west with sluggish currents and deep channels resembling the estuaries of drowned rivers; while those that enter from opposite directions are swift and shallow. at the western end of lake erie are found submerged caves containing stalactites, and old meadows and forest grounds are now under water. it is thus seen that the water of the lakes is rising along their southwestern shores, while from their northeastern shores it is being withdrawn. the region of the great lakes is therefore warping; it is rising in the northeast as compared with the southwest. from old bench marks and records of lake levels it has been estimated that _the rate of warping_ amounts to five inches a century for every one hundred miles. it is calculated that the water of lake michigan is rising at chicago at the rate of nine or ten inches per century. the divide at this point between the tributaries of the mississippi and lake michigan is but eight feet above the mean stage of the lake. if the canting of the region continues at its present rate, in a thousand years the waters of the lake will here overflow the divide. in three thousand five hundred years all the lakes except ontario will discharge by this outlet, via the illinois and mississippi rivers, into the gulf of mexico. the present outlet by the niagara river will be left dry, and the divide between the st. lawrence and the mississippi systems will have shifted from chicago to the vicinity of buffalo. =physiographic effects of oscillations.= we have already mentioned several of the most important effects of movements of elevation and depression, such as their effects on rivers, the mantle of waste (pp. , ), and the forms of coasts (p. ). movements of elevation--including uplifts by folding and fracture of the crust to be noticed later--are the necessary conditions for erosion by whatever agent. they determine the various agencies which are to be chiefly concerned m the wear of any land,--whether streams or glaciers, weathering or the wind,--and the degree of their efficiency. the lands must be uplifted before they can be eroded, and since they must be eroded before their waste can be deposited, movements of elevation are a prerequisite condition for sedimentation also. subsidence is a necessary condition for deposits of great thickness, such as those of the great valley of california and the indo-gangetic plain (p. ), the mississippi delta (p. ), and the still more important formations of the continental delta in gradually sinking troughs (p. ). it is not too much to say that the character and thickness of each formation of the stratified rocks depend primarily on these crustal movements. along the baltic coast of sweden, bench marks show that the sea is withdrawing from the land at a rate which at the north amounts to between three and four feet per century; towards the south the rate decreases. south of stockholm, until recent years, the sea has gained upon the land, and here in several seaboard towns streets by the shore are still submerged. the rate of oscillation increases also from the coast inland. on the other hand, along the german coast of the baltic the only historic fluctuations of sea level are those which may be accounted for by variations due to changes in rainfall. in celsius explained the changes of level of the swedish coast as due to a lowering of the baltic instead of to an elevation of the land. are the facts just stated consistent with his theory? [illustration: fig. . old strand lines, tadousac, quebec] at the little town of tadousac--where the saguenay river empties into the st. lawrence--there are terraces of old sea beaches, some almost as fresh as recent railway fills, the highest standing two hundred and thirty feet above the river (fig. ). here the saguenay is eight hundred and forty feet in depth, and the tide ebbs and flows far up its stream. was its channel cut to this depth by the river when the land was at its present height? what oscillations are here recorded, and to what amount? [illustration: fig. . diagram showing ruins of temple, north of naples _c_, ancient sea cliff; _m_, marble pillars, dotted where bored by mollusks; _sl_, sea level] a few miles north of naples, italy, the ruins of an ancient roman temple lie by the edge of the sea, on a narrow plain which is overlooked in the rear by an old sea cliff (fig. ). three marble pillars are still standing. for eleven feet above their bases these columns are uninjured, for to this height they were protected by an accumulation of volcanic ashes; but from eleven to nineteen feet they are closely pitted with the holes of boring marine mollusks. from these facts trace the history of the oscillations of the region. [illustration: fig. . section in a region of folded rocks] foldings of the crust the oscillations which we have just described leave the strata not far from their original horizontal attitude. figure represents a region in which movements of a very different nature have taken place. here, on either side of the valley _v_, we find outcrops of layers tilted at high angles. sections along the ridge _r_ show that it is composed of layers which slant inward from either side. in places the outcropping strata stand nearly on edge, and on the right of the valley they are quite overturned; a shale _sh_ has come to overlie a limestone _lm_ although the shale is the older rock, whose original position was beneath the limestone. [illustration: fig. . dip and strike] it is not reasonable to suppose that these rocks were deposited in the attitude in which we find them now; we must believe that, like other stratified rocks, they were outspread in nearly level sheets upon the ocean floor. since that time they must have been deformed. layers of solid rock several miles in thickness have been crumpled and folded like soft wax in the hand, and a vast denudation has worn away the upper portions of the folds, in part represented in our section by dotted lines. =dip and strike.= in districts where the strata have been disturbed it is desirable to record their attitude. this is most easily done by taking the angle at which the strata are inclined and the compass direction in which they slant. it is also convenient to record the direction in which the outcrop of the strata trends across the country. [illustration: fig. . an anticline, maryland] the inclination of a bed of rocks to the horizon is its _dip_ (fig. ). the amount of the dip is the angle made with a horizontal plane. the dip of a horizontal layer is zero, and that of a vertical layer is °. the direction of the dip is taken with the compass. thus a geologist's notebook in describing the attitude of outcropping strata contains many such entries as these: dip ° north, or dip ° south ° west,--meaning in the latter case that the amount of the dip is ° and the direction of the dip bears ° west of south. the line of intersection of a layer with the horizontal plane is the _strike_. the strike always runs at right angles to the dip. dip and strike may be illustrated by a book set aslant on a shelf. the dip is the acute angle made with the shelf by the side of the book, while the strike is represented by a line running along the book's upper edge. if the dip is north or south, the strike runs east and west. [illustration: fig. . folded strata, coast of england a syncline in the center, with an anticline on either side] =folded structures.= an upfold, in which the strata dip away from a line drawn along the crest and called the axis of the fold, is known as an _anticline_ (fig. ). a downfold, where the strata dip from either side toward the axis of the trough, is called a _syncline_ (fig. ). there is sometimes seen a downward bend in horizontal or gently inclined strata, by which they descend to a lower level. such a single flexure is a _monocline_ (fig. ). [illustration: fig. . a monocline] =degrees of folding.= folds vary in degree from broad, low swells, which can hardly be detected, to the most highly contorted and complicated structures. in _symmetric_ folds (figs. and ) the dips of the rocks on each side the axis of the fold are equal. in _unsymmetrical_ folds one limb is steeper than the other, as in the anticline in figure . in _overturned_ folds (figs. and ) one limb is inclined beyond the perpendicular. _fan folds_ have been so pinched that the original anticlines are left broader at the top than at the bottom (fig. ). [illustration: fig. . overturned fold, vermont] in folds where the compression has been great the layers are often found thickened at the crest and thinned along the limbs ( ). where strong rocks such as heavy limestones are folded together with weak rocks such as shales, the strong rocks are often bent into great simple folds, while the weak rocks are minutely crumpled. [illustration: fig. . fan folds, the alps] =systems of folds.= as a rule, folds occur in systems. over the appalachian mountain belt, for example, extending from northeastern pennsylvania to northern alabama and georgia, the earth's crust has been thrown into a series of parallel folds whose axes run from northeast to southwest (fig. ). in pennsylvania one may count a score or more of these earth waves,--some but from ten to twenty miles in length, and some extending as much as two hundred miles before they die away. on the eastern part of this belt the folds are steeper and more numerous than on the western side. [illustration: fig. . folds with layers thickened at the crest and thinned along the limbs] =cause and conditions of folding.= the sections which we have studied suggest that rocks are folded by lateral pressure. while a single, simple fold might be produced by a heave, a series of folds, including overturns, fan folds, and folds thickened on their crests at the expense of their limbs, could only be made in one way,--by pressure from the side. experiment has reproduced all forms of folds by subjecting to lateral thrust layers of plastic material such as wax. vast as the force must have been which could fold the solid rocks of the crust as one may crumple the leaves of a magazine in the fingers, it is only under certain conditions that it could have produced the results which we see. rocks are brittle, and it is only when under a _heavy load_ and by _great pressure slowly applied_, that they can thus be folded and bent instead of being crushed to pieces. under these conditions, experiments prove that not only metals such as steel, but also brittle rocks such as marble, can be deformed and molded and made to flow like plastic clay. [illustration: fig. . relief map of the northern appalachian region from bingham's _geographic influences in american history_] =zone of flow, zone of flow and fracture, and zone of fracture.= we may believe that at depths which must be reckoned in tens of thousands of feet the load of overlying rocks is so great that rocks of all kinds yield by folding to lateral pressure, and flow instead of breaking. indeed, at such profound depths and under such inconceivable weight no cavity can form, and any fractures would be healed at once by the welding of grain to grain. at less depths there exists a zone where soft rocks fold and flow under stress, and hard rocks are fractured; while at and near the surface hard and soft rocks alike yield by fracture to strong pressure. structures developed in compressed rocks deformed rocks show the effects of the stresses to which they have yielded, not only in the immense folds into which they have been thrown but in their smallest parts as well. a hand specimen of slate, or even a particle under the microscope, may show plications similar in form and origin to the foldings which have produced ranges of mountains. a tiny flake of mica in the rocks of the alps may be puckered by the same resistless forces which have folded miles of solid rock to form that lofty range. =slaty cleavage.= rocks which have yielded to pressure often split easily in a certain direction across the bedding planes. this cleavage is known as slaty cleavage, since it is most perfectly developed in fine-grained, homogeneous rocks, such as slates, which cleave to the thin, smooth-surfaced plates with which we are familiar in the slates used in roofing and for ciphering and blackboards. in coarse-grained rocks, pressure develops more distant partings which separate the rocks into blocks. slaty cleavage cannot be due to lamination, since it commonly crosses bedding planes at an angle, while these planes have been often well-nigh or quite obliterated. examining slate with a microscope, we find that its cleavage is due to the grain of the rock. its particles are flattened and lie with their broad faces in parallel planes, along which the rock naturally splits more easily than in any other direction. the irregular grains of the mud which has been altered to slate have been squeezed flat by a pressure exerted at right angles to the plane of cleavage. cleavage is found only in folded rocks, and, as we may see in figure , the strike of the cleavage runs parallel to the strike of the strata and the axis of the folds. the dip of the cleavage is generally steep, hence the pressure was nearly horizontal. the pressure which has acted at right angles to the cleavage, and to which it is due, is the same lateral pressure which has thrown the strata into folds. [illustration: fig. . slaty cleavage] we find additional proof that slates have undergone compression at right angles to their cleavage in the fact that any inclusions in them, such as nodules and fossils, have been squeezed out of shape and have their long diameters lying in the planes of cleavage. that pressure is competent to cause cleavage is shown by experiment. homogeneous material of fine grain, such as beeswax, when subjected to heavy pressure cleaves at right angles to the direction of the compressing force. =rate of folding.= all the facts known with regard to rock deformation agree that it is a secular process, taking place so slowly that, like the deepening of valleys by erosion, it escapes the notice of the inhabitants of the region. it is only under stresses slowly applied that rocks bend without breaking. the folds of some of the highest mountains have risen so gradually that strong, well-intrenched rivers which had the right of way across the region were able to hold to their courses, and as a circular saw cuts its way through the log which is steadily driven against it, so these rivers sawed their gorges through the fold as fast as it rose beneath them. streams which thus maintain the course which they had antecedent to a deformation of the region are known as _antecedent_ streams. examples of such are the sutlej and other rivers of india, whose valleys trench the outer ranges of the himalayas and whose earlier river deposits have been upturned by the rising ridges. on the other hand, mountain crests are usually divides, parting the head waters of different drainage systems. in these cases the original streams of the region have been broken or destroyed by the uplift of the mountain mass across their paths. on the whole, which have worked more rapidly, processes of deformation or of denudation? [illustration: fig. . an unroofed anticline] land forms due to folding as folding goes on so slowly, it is never left to form surface features unmodified by the action of other agencies. an anticlinal fold is attacked by erosion as soon as it begins to rise above the original level, and the higher it is uplifted, and the stronger are its slopes, the faster is it worn away. even while rising, a young upfold is often thus unroofed, and instead of appearing as a long, smooth, boat-shaped ridge, it commonly has had opened along the rocks of the axis, when these are weak, a valley which is overlooked by the infacing escarpments of the hard layers of the sides of the fold (fig. ). under long-continued erosion, anticlines may be degraded to valleys, while the synclines of the same system may be left in relief as ridges (fig. ). =folded mountains.= the vastness of the forces which wrinkle the crust is best realized in the presence of some lofty mountain range. all mountains, indeed, are not the result of folding. some, as we shall see, are due to upwarps or to fractures of the crust; some are piles of volcanic material; some are swellings caused by the intrusion of molten matter beneath the surface; some are the relicts left after the long denudation of high plateaus. [illustration: fig. . mountain peaks carved in folded strata, rocky mountains, montana] but most of the mountain ranges of the earth, and some of the greatest, such as the alps and the himalayas, were originally mountains of folding. the earth's crust has wrinkled into a fold; or into a series of folds, forming a series of parallel ridges and intervening valleys; or a number of folds have been mashed together into a vast upswelling of the crust, in which the layers have been so crumpled and twisted, overturned and crushed, that it is exceedingly difficult to make out the original structure. the close and intricate folds seen in great mountain ranges were formed, as we have seen, deep below the surface, within the zone of folding. hence they may never have found expression in any individual surface features. as the result of these deformations deep under ground the surface was broadly lifted to mountain height, and the crumpled and twisted mountain structures are now to be seen only because erosion has swept away the heavy cover of surface rocks under whose load they were developed. [illustration: fig. . section of a portion of the alps] when the structure of mountains has been deciphered it is possible to estimate roughly the amount of horizontal compression which the region has suffered. if the strata of the folds of the alps were smoothed out, they would occupy a belt seventy-four miles wider than that to which they have been compressed, or twice their present width. a section across the appalachian folds in pennsylvania shows a compression to about two thirds the original width; the belt has been shortened thirty-five miles in every hundred. considering the thickness of their strata, the compression which mountains have undergone accounts fully for their height, with enough to spare for all that has been lost by denudation. the appalachian folds involve strata thirty thousand feet in thickness. assuming that the folded strata rested on an unyielding foundation, and that what was lost in width was gained in height, what elevation would the range have reached had not denudation worn it as it rose? =the life history of mountains.= while the disturbance and uplift of mountain masses are due to deformation, their sculpture into ridges and peaks, valleys and deep ravines, and all the forms which meet the eye in mountain scenery, excepting in the very youngest ranges, is due solely to erosion. we may therefore classify mountains according to the degree to which they have been dissected. the juras are an example of the stage of early youth, in which the anticlines still persist as ridges and the synclines coincide with the valleys; this they owe as much to the slight height of their uplift as to the recency of its date (fig. ). [illustration: fig. . section of a portion of the jura mountains] the alps were upheaved at various times (fig. ), the last uplift being later than the uplift of the juras, but to so much greater height that erosion has already advanced them well on towards maturity. the mountain mass has been cut to the core, revealing strange contortions of strata which could never have found expression at the surface. sharp peaks, knife-edged crests, deep valleys with ungraded slopes subject to frequent landslides, are all features of alpine scenery typical of a mountain range at this stage in its life history. they represent the survival of the hardest rocks and the strongest structures, and the destruction of the weaker in their long struggle for existence against the agents of erosion. although miles of rock have been removed from such ranges as the alps, we need not suppose that they ever stood much, if any, higher than at present. all this vast denudation may easily have been accomplished while their slow upheaval was going on; in several mountain ranges we have evidence that elevation has not yet ceased. [illustration: fig. . young mountains, rocky mountains of canada] under long denudation mountains are subdued to the forms characteristic of old age. the lofty peaks and jagged crests of their earlier life are smoothed down to low domes and rounded crests. the southern appalachians and portions of the hartz mountains in germany (fig. ) are examples of mountains which have reached this stage. [illustration: fig. . subdued mountains, the hartz mountains, germany] there are numerous regions of upland and plains in which the rocks are found to have the same structure that we have seen in folded mountains; they are tilted, crumpled, and overturned, and have clearly suffered intense compression. we may infer that their folds were once lifted to the height of mountains and have since been wasted to low-lying lands. such a section as that of figure illustrates how ancient mountains may be leveled to their roots, and represents the final stage to which even the alps and the himalayas must sometime arrive. mountains, perhaps of alpine height, once stood about lake superior; a lofty range once extended from new england and new jersey southwestward to georgia along the piedmont belt. in our study of historic geology we shall see more clearly how short is the life of mountains as the earth counts time, and how great ranges have been lifted, worn away, and again upheaved into a new cycle of erosion. =the sedimentary history of folded mountains.= we may mention here some of the conditions which have commonly been antecedent to great foldings of the crust. . mountain ranges are made of belts of enormously and exceptionally thick sediments. the strata of the appalachians are thirty thousand feet thick, while the same formations thin out to five thousand feet in the mississippi valley. the folds of the wasatch mountains involve strata thirty thousand feet thick, which thin to two thousand feet in the region of the plains. . the sedimentary strata of which mountains are made are for the most part the shallow-water deposits of continental deltas. mountain ranges have been upfolded along the margins of continents. . shallow-water deposits of the immense thickness found in mountain ranges can be laid only in a gradually sinking area. a profound subsidence, often to be reckoned in tens of thousands of feet, precedes the upfolding of a mountain range. thus the history of mountains of folding is as follows: for long ages the sea bottom off the coast of a continent slowly subsides, and the great trough, as fast as it forms, is filled with sediments, which at last come to be many thousands of feet thick. the downward movement finally ceases. a slow but resistless pressure sets in, and gradually, and with a long series of many intermittent movements, the vast mass of accumulated sediments is crumpled and uplifted into a mountain range. fractures and dislocations of the crust considering the immense stresses to which the rocks of the crust are subjected, it is not surprising to find that they often yield by fracture, like brittle bodies, instead of by folding and flowing, like plastic solids. whether rocks bend or break depends on the character and condition of the rocks, the load of overlying rocks which they bear, and the amount of the force and the slowness with which it is applied. =joints.= at the surface, where their load is least, we find rocks universally broken into blocks of greater or less size by partings known as joints. under this name are included many division planes caused by cooling and drying; but it is now generally believed that the larger and more regular joints, especially those which run parallel to the dip and strike of the strata, are fractures due to up-and-down movements and foldings and twistings of the rocks. [illustration: fig. . joints utilized by a river in widening its valley, iowa] joints are used to great advantage in quarrying, and we have seen how they are utilized by the weather in breaking up rock masses, by rivers in widening their valleys, by the sea in driving back its cliffs, by glaciers in plucking their beds, and how they are enlarged in soluble rocks to form natural passageways for underground waters. the ends of the parted strata match along both sides of joint planes; in. joints there has been little or no displacement of the broken rocks. [illustration: fig. . a normal fault] =faults.= in figure the rocks have been both broken and dislocated along the plane _ff´_. one side must have been moved up or down past the other. such a dislocation is called a fault. the amount of the displacement, as measured by the vertical distance between the ends of a parted layer, is the _throw_ (_cd_). the angle (_ff´v_) which the fault plane makes with the vertical is the _hade_. in figure the right side has gone down relatively to the left; the right is the side of the downthrow, while the left is the side of the upthrow. where the fault plane is not vertical the surfaces on the two sides may be distinguished as the _hanging wall_ (that on the right of figure ) and the _foot wall_ (that on the left of the same figure). faults differ in throw from a fraction of an inch to many thousands of feet. =slickensides.= if we examine the walls of a fault, we may find further evidence of movement in the fact that the surfaces are polished and grooved by the enormous friction which they have suffered as they have ground one upon the other. these appearances, called slickensides, have sometimes been mistaken for the results of glacial action. =normal faults.= faults are of two kinds,--normal faults and thrust faults. normal faults, of which figure is an example, hade to the downthrow; the hanging wall has gone down. the total length of the strata has been increased by the displacement. it seems that the strata have been stretched and broken, and that the blocks have readjusted themselves under the action of gravity as they settled. =thrust faults.= thrust faults hade to the upthrow; the hanging wall has gone up. clearly such faults, where the strata occupy less space than before, are due to lateral thrust. folds and thrust faults are closely associated. under lateral pressure strata may fold to a certain point and then tear apart and fault along the surface of least resistance. under immense pressure strata also break by shear without folding. thus, in figure , the rigid earth block under lateral thrust has found it easier to break along the fault plane than to fold. where such faults are nearly horizontal they are distinguished as _thrust planes_. [illustration: fig. . a thrust fault] in all thrust faults one mass has been pushed over another, so as to bring the underlying and older strata upon younger beds; and when the fault planes are nearly horizontal, and especially when the rocks have been broken into many slices which have slidden far one upon another, the true succession of strata is extremely hard to decipher. in the selkirk mountains of canada the basement rocks of the region have been driven east for seven miles on a thrust plane, over rocks which originally lay thousands of feet above them. along the western appalachians, from virginia to georgia, the mountain folds are broken by more than fifteen parallel thrust planes, running from northeast to southwest, along which the older strata have been pushed westward over the younger. the longest continuous fault has been traced three hundred and seventy-five miles, and the greatest horizontal displacement has been estimated at not less than eleven miles. =crush breccia.= rocks often do not fault with a clean and simple fracture, but along a zone, sometimes several yards in width, in which they are broken to fragments. it may occur also that strata which as a whole yield to lateral thrust by folding include beds of brittle rocks, such as thin-layered limestones, which are crushed to pieces by the strain. in either case the fragments when recemented by percolating waters form a rock known as a _crush breccia_ (pronounced _bretcha_)(fig. ). [illustration: fig. . breccia] breccia is a term applied to any rock formed of cemented _angular_ fragments. this rock may be made by the consolidation of volcanic cinders, of angular waste at the foot of cliffs, or of fragments of coral torn by the waves from coral reefs, as well as of strata crushed by crustal movements. surface features due to dislocations =fault scarps.= a fault of recent date may be marked at surface by a scarp, because the face of the upthrown block has not yet been worn to the level of the downthrow side. after the upthrown block has been worn down to this level, differential erosion produces fault scarps wherever weak rocks and resistant rocks are brought in contact along the fault plane; and the harder rocks, whether on the upthrow or the downthrow side, emerge in a line of cliffs. where a fault is so old that no abrupt scarps appear, its general course is sometimes marked by the line of division between highland and lowland or hill and plain. great faults have sometimes brought ancient crystalline rocks in contact with weaker and younger sedimentary rocks, and long after erosion has destroyed all fault scarps the harder crystallines rise in an upland of rugged or mountainous country which meets the lowland along the line of faulting. [illustration: fig. . a concealed fault this fault may be inferred from the changes in strata in passing along the strike, as from _b_ to _a´_ and from _c_ to _b´_] the vast majority of faults give rise to no surface features. the faulted region may be old enough to have been baseleveled, or the rocks on both sides of the line of dislocation may be alike in their resistance to erosion and therefore have been worn down to a common slope. the fault may be entirely concealed by the mantle of waste, and in such cases it can be inferred from abrupt changes in the character or the strike and dip of the strata where they may outcrop near it (fig. ). [illustration: fig. . east-west section across the broken plateau north of the grand canyon of the colorado river, arizona] the plateau trenched by the grand canyon of the colorado river exhibits a series of magnificent fault scarps whose general course is from north to south, marking the edges of the great crust blocks into which the country has been broken. the highest part of the plateau is a crust block ninety miles long and thirty-five miles in maximum width, which has been hoisted to nine thousand three hundred feet above, sea level. on the east it descends four thousand feet by a monoclinal fold, which passes into a fault towards the north. on the west it breaks down by a succession of terraces faced by fault scarps. the throw of these faults varies from seven hundred feet to more than a mile. the escarpments, however, are due in a large degree to the erosion of weaker rock on the downthrow side. [illustration: fig. . the fault separating the highlands and the lowlands, scotland] the highlands of scotland (fig. ) meet the lowlands on the south with a bold front of rugged hills along a line of dislocation which runs across the country from sea to sea. on the one side are hills of ancient crystalline rocks whose crumpled structures prove that they are but the roots of once lofty mountains; on the other lies a lowland of sandstone and other stratified rocks formed from the waste of those long-vanished mountain ranges. remnants of sandstone occur in places on the north of the great fault, and are here seen to rest on the worn and fairly even surface of the crystallines. we may infer that these ancient mountains were reduced along their margins to low plains, which were slowly lowered beneath the sea to receive a cover of sedimentary rocks. still later came an uplift and dislocation. on the one side erosion has since stripped off the sandstones for the most part, but the hard crystalline rocks yet stand in bold relief. on the other side the weak sedimentary rocks have been worn down to lowlands. =rift valleys.= in a broken region undergoing uplift or the unequal settling which may follow, a slice inclosed between two fissures may sink below the level of the crust blocks on either side, thus forming a linear depression known as a rift valley, or valley of fracture. [illustration: fig. . section from the mountains of palestine to the mountains of moab across the dead sea _a_, ancient schists; _b_, carboniferous strata; _c_, _d_, and _e_, cretaceous strata] one of the most striking examples of this rare type of valley is the long trough which runs straight from the lebanon mountains of syria on the north to the red sea on the south, and whose central portion is occupied by the jordan valley and the dead sea. the plateau which it gashes has been lifted more than three thousand feet above sea level, and the bottom of the trough reaches a depth of two thousand six hundred feet below that level in parts of the dead sea. south of the dead sea the floor of the trough rises somewhat above sea level, and in the gulf of akabah again sinks below it. this uneven floor could be accounted for either by the profound warping of a valley of erosion or by the unequal depression of the floor of a rift valley. but that the trough is a true valley of fracture is proved by the fact that on either side it is bounded by fault scarps and monoclinal folds. the keystone of the arch has subsided. many geologists believe that the jordan-akabah trough, the long narrow basin of the red sea, and the chain of down-faulted valleys which in africa extends from the strait of bab-el-mandeb as far south as lake nyassa--valleys which contain more than thirty lakes--belong to a single system of dislocation. should you expect the lateral valleys of a rift valley at the time of its formation to enter it as hanging valleys or at a common level? =block mountains.= dislocations take place on so grand a scale that by the upheaval of blocks of the earth's crust or the downfaulting of the blocks about one which is relatively stationary, mountains known as block mountains are produced. a tilted crust block may present a steep slope on the side upheaved and a more gentle descent on the side depressed. [illustration: fig. . block mountains, southern oregon] =the basin ranges.= the plateaus of the united states bounded by the rocky mountains on the east, and on the west by the ranges which front the pacific, have been profoundly fractured and faulted. the system of great fissures by which they are broken extends north and south, and the long, narrow, tilted crust blocks intercepted between the fissures give rise to the numerous north-south ranges of the region. some of the tilted blocks, as those of southern oregon, are as yet but moderately carved by erosion, and shallow lakes lie on the waste that has been washed into the depressions between them (fig. ). we may therefore conclude that their displacement is somewhat recent. others, as those of nevada, are so old that they have been deeply dissected; their original form has been destroyed by erosion, and the intermontane depressions are occupied by wide plains of waste. =dislocations and river valleys.= before geologists had proved that rivers can by their own unaided efforts cut deep canyons, it was common to consider any narrow gorge as a gaping fissure of the crust. this crude view has long since been set aside. a map of the plateaus of northern arizona shows how independent of the immense faults of the region is the course of the colorado river. in the alps the tunnels on the saint gotthard railway pass six times beneath the gorge of the reuss, but at no point do the rocks show the slightest trace of a fault. [illustration: fig. . fault crossing valley in japan] =rate of dislocation.= so far as human experience goes, the earth movements which we have just studied, some of which have produced deep-sunk valleys and lofty mountain ranges, and faults whose throw is to be measured in thousands of feet, are slow and gradual. they are not accomplished by a single paroxysmal effort, but by slow creep and a series of slight slips continued for vast lengths of time. in the aspen mining district in colorado faulting is now going on at a comparatively rapid rate. although no sudden slips take place, the creep of the rock along certain planes of faulting gradually bends out of shape the square-set timbers in horizontal drifts and has closed some vertical shafts by shifting the upper portion across the lower. along one of the faults of this region it is estimated that there has been a movement of at least four hundred feet since the glacial epoch. more conspicuous are the instances of active faulting by means of sudden slips. in there occurred along an old fault plane in japan a slip which produced an earth rent traced for fifty miles (fig. ). the country on one side was depressed in places twenty feet below that on the other, and also shifted as much as thirteen feet horizontally in the direction of the fault line. in a slip occurred for forty miles on the great line of dislocation which runs along the eastern base of the sierra nevada mountains. in the owens valley, california, the throw amounted to twenty-five feet in places, with a horizontal movement along the fault line of as much as eighteen feet. both this slip and that in japan just mentioned caused severe earthquakes. for the sake of clearness we have described oscillations, foldings, and fractures of the crust as separate processes, each giving rise to its own peculiar surface features, but in nature earth movements are by no means so simple,--they are often implicated with one another: folds pass into faults; in a deformed region certain rocks have bent, while others under the same strain, but under different conditions of plasticity and load, have broken; folded mountains have been worn to their roots, and the peneplains to which they have been denuded have been upwarped to mountain height and afterwards dissected,--as in the case of the allegheny ridges, the southern carpathians, and other ranges,--or, as in the case of the sierra nevada mountains, have been broken and uplifted as mountains of fracture. draw the following diagrams, being careful to show the direction in which the faulted blocks have moved, by the position of the two parts of some well-defined layer of limestone, sandstone, or shale, which occurs on each side of the fault plane, as in figure . . a normal fault with a hade of °, the original fault scarp remaining. . a normal fault with a hade of °, the original fault scarp worn away, showing cliffs caused by harder strata on the downthrow side. . a thrust fault with a hade of °, showing cliffs due to harder strata outcropping on the downthrow. . a thrust fault with a hade of °, with surface baseleveled. . in a region of normal faults a coal mine is being worked along the seam of coal _ab_ (fig. ). at _b_ it is found broken by a fault f which hades toward _a_. to find the seam again, should you advise tunneling up or down from _b_? [illustration: fig. ] . in a vertical shaft of a coal mine the same bed of coal is pierced twice at different levels because of a fault. draw a diagram to show whether the fault is normal or a thrust. [illustration: fig. . ridges to be explained by faulting] . copy the diagram in figure , showing how the two ridges may be accounted for by a single resistant stratum dislocated by a fault. is the fault a _strike fault_, i.e. one running parallel with the strike of the strata, or a _dip fault_, one running parallel with the direction of the dip? [illustration: fig. . earth block of tilted strata, with included seam of coal _cc_] . draw a diagram of the block in figure as it would appear if dislocated along the plane _efg_ by a normal fault whose throw equals one fourth the height of the block. is the fault a strike or a dip fault? draw a second diagram showing the same block after denudation has worn it down below the center of the upthrown side. note that the outcrop of the coal seam is now deceptively repeated. this exercise may be done in blocks of wood instead of drawings. [illustration: fig. . _a_ and _b_. repeated outcrops of same strata] . draw diagrams showing by dotted lines the conditions both of _a_ and _b_, figure , after deformation had given the strata their present attitude. [illustration: fig. . a block mountain] . what is the attitude of the strata of this earth block, figure ? what has taken place along the plane _baf_? when did the dislocation occur compared with the folding of the strata? with the erosion of the valleys on the right-hand side of the mountain? with the deposition of the sediments _efg_? do you find any remnants of the original surface _baf_ produced by the dislocation? from the left-hand side of the mountain infer what was the relief of the region before the dislocation. give the complete history recorded in the diagram from the deposition of the strata to the present. [illustration: fig. . a faulted lava flow _aa´_] . which is the older fault, in figure , _f_ or _f´_? when did the lava flow occur? how long a time elapsed between the formation of the two faults as measured in the work done in the interval? how long a time since the formation of the later fault? [illustration: fig. . measurement of the thickness of inclined strata] . measure by the scale the thickness _bc_ of the coal-bearing strata outcropping from _a_ to _b_ in figure . on any convenient scale draw a similar section of strata with a dip of ° outcropping along a horizontal line normal to the strike one thousand feet in length, and measure the thickness of the strata by the scale employed. the thickness may also be calculated by trigonometry. [illustration: fig. . unconformity between parallel strata] [illustration: fig. . unconformity between non-parallel strata] unconformity strata deposited one upon, another in an unbroken succession are said to be _conformable_. but the continuous deposition of strata is often interrupted by movements of the earth's crust, old sea floors are lifted to form land and are again depressed beneath the sea to receive a cover of sediments only after an interval during which they were carved by subaërial erosion. an erosion surface which thus parts older from younger strata is known as an _unconformity_, and the strata above it are said to be _unconformable_ with the rocks below, or to rest unconformably upon them. an unconformity thus records movements of the crust and a consequent break in the deposition of the strata. it denotes a period of land erosion of greater or less length, which may sometimes be roughly measured by the stage in the erosion cycle which the land surface had attained before its burial. unconformable strata may be _parallel_, as in figure , where the record includes the deposition of strata _a_, their emergence, the erosion of the land surface _ss_, a submergence and the deposit of the strata _b_, and lastly, emergence and the erosion of the present surface _s´s´_. [illustration: fig. . carboniferous limestone resting unconformably on early silurian slates, yorkshire, england] often the earth movements to which the uplift or depression was due involved tilting or folding of the earlier strata, so that the strata are now nonparallel as well as unconformable. in figure , for example, the record includes deposition, uplift, and _tilting_ of _a_; erosion, depression, the deposit of _b_; and finally the uplift which has brought the rocks to open air and permitted the dissection by which the unconformity is revealed. from this section we infer that during early silurian times the area was sea, and thick sea muds were laid upon it. these were later altered to hard slates by pressure and upfolded into mountains. during the later silurian and the devonian the area was land and suffered vast denudation. in the carboniferous period it was lowered beneath the sea and received a cover of limestone. [illustration: fig. . diagram illustrating how the age of mountains is determined] =the age of mountains.= it is largely by means of unconformities that we read the history of mountain making and other deformations and movements of the crust. in figure , for example, the deformation which upfolded the range of mountains took place after the deposit of the series of strata a of which the mountains are composed, and before the deposit of the stratified rocks, which rest unconformably on a and have not shared their uplift. [illustration: fig. . section of mountain range showing repeated uplifts _a_, strata whose folding formed a mountain range; on, baseleveled surface produced by long denudation of the mountains; _b_, tilted strata resting unconformably on _a_; _c_, horizontal strata parted from _b_ by the unconformity _u´u´_. the first uplift of the range preceded the period of time when _b_ was deposited. the and uplift, to which the present mountains owe their height, was later than this period but earlier than the period when strata _c_ were laid] most great mountain ranges, like the sierra nevada and the alps, mark lines of weakness along which the earth's crust has yielded again and again during the long ages of geological time. the strata deposited at various times about their flanks have been infolded by later crumplings with the original mountain mass, and have been repeatedly crushed, inverted, faulted, intruded with igneous rocks, and denuded. the structure of great mountain ranges thus becomes exceedingly complex and difficult to read. a comparatively simple case of repeated uplift is shown in figure . in the section of a portion of the alps shown in figure a far more complicated history may be deciphered. [illustration: fig. . unconformity showing buried valleys _lm_, limestone; _sh_, shale; _r_, _r´_, and _r´´_, river silts filling eroded valleys in the limestone. the upper surface of the limestone is evidently a land surface developed by erosion. the valleys which trench it are narrow and steep-sided; hence the land surface had not reached maturity. the sands and muds, now hardened to firm rock, which fill these valleys, _r_, _r´_, and _r´´_, contain no relics of the sea, but instead the remains of land animals and plants. they are river deposits, and we may infer that owing to a subsidence the young rivers ceased to degrade their channels and slowly filled their gorges with sands and silts. the overlying shale records a further depression which brought the lanes below the level of the sea. a section similar to this is to be seen in the coal mines of bernissant, belgium, where a gorge twice as deep as that of niagara was discovered within whose ancient river deposits were found entombed the skeletons of more than a score of the huge reptiles characteristic of the age when the gorge was cut and filled] [illustration: fig. . unconformity showing buried mountains, scotland _gn_, ancient crystalline rocks; _ss_, marine sandstones. the surface _bb_ of the ancient crystalline rocks is mountainous, with peaks rising to a height of as much as three thousand feet. it is one of the most ancient land surfaces on the planet and is covered unconformably with pre-cambrian sandstones thousands of feet in thickness, in which the torridonian mountains of scotland have been carved. what has been the history of the region since the mountainous surface _bb_ was produced by erosion?] =unconformities in the colorado canyon, arizona.= how geological history may be read in unconformities is further illustrated in figures and >. the dark crystalline rocks _a_ at the bottom of the canyon are among the most ancient known, and are overlain unconformably by a mass of tilted coarse marine sandstones _b_, whose total thickness is not seen in the diagram and measures twelve thousand feet perpendicularly to the dip. both _a_ and _b_ rise to a common level _nn´_ and upon them rest the horizontal sea-laid strata _c_, in which the upper portion of the canyon has been cut. [illustration: fig. . diagram of wall of the colorado canyon, arizona, showing unconformities] note that the crystalline rocks a have been crumpled and crushed. comparing their structure with that of folded mountains, what do you infer as to their relief after their deformation? to which surface were they first worn down, _mm´_ or _nm_? describe and account for the surface _mm´_. how does it differ from the surface of the crystalline rocks seen in the torridonian mountains (fig. ), and why? this surface _mm´_ is one of the oldest land surfaces of which any vestige remains. it is a bit of fossil geography buried from view since the earliest geological ages and recently brought to light by the erosion of the canyon. [illustration: fig. . view of the north wall of the grand canyon of the colorado river, arizona, showing the unconformities illustrated in figure ] how did the surface _mm´_ come to receive its cover of sandstones _b_? from the thickness and coarseness of these sediments draw inferences as to the land mass from which they were derived. was it rising or subsiding? high or low? were its streams slow or swift? was the amount of erosion small or great? note the strong dip of these sandstones _b_. was the surface _mm´_ tilted as now when the sandstones were deposited upon it? when was it tilted? draw a diagram showing the attitude of the rocks after this tilting occurred, and their height relative to sea level. the surface _nn´_ is remarkably even, although diversified by some low hills which rise into the bedded rocks of _c_, and it may be traced for long distances up and down the canyon. were the layers of _b_ and the surface _mm´_ always thus cut short by _nn´_ as now? what has made the surface _nn´_ so even? how does it come to cross the hard crystalline rocks a and the weaker sandstones _b_ at the same impartial level? how did the sediments of _c_ come to be laid upon it? give now the entire history recorded in the section, and in addition that involved in the production of the platform _p_, shown in figure , and that of the cutting of the canyon. how does the time involved in the cutting of the canyon compare with that required for the production of the surfaces _mm´_, _nn´_, and _p_? chapter x earthquakes any sudden movement of the rocks of the crust, as when they tear apart when a fissure is formed or extended, or slip from time to time along a growing fault, produces a jar called an earthquake, which spreads in all directions from the place of disturbance. =the charleston earthquake.= on the evening of august , , the city of charleston, s.c., was shaken by one of the greatest earthquakes which has occurred in the united states. a slight tremor which rattled the windows was followed a few seconds later by a roar, as of subterranean thunder, as the main shock passed beneath the city. houses swayed to and fro, and their heaving floors overturned furniture and threw persons off their feet as, dizzy and nauseated, they rushed to the doors for safety. in sixty seconds a number of houses were completely wrecked, fourteen thousand chimneys were toppled over, and in all the city scarcely a building was left without serious injury. in the vicinity of charleston railways were twisted and trains derailed. fissures opened in the loose superficial deposits, and in places spouted water mingled with sand from shallow underlying aquifers. the point of origin, or _focus_, of the earthquake was inferred from subsequent investigations to be a rent in the rocks about twelve miles beneath the surface. from the center of greatest disturbance, which lay above the focus, a few miles northwest of the city, the surface shock traveled outward in every direction, with decreasing effects, at the rate of nearly two hundred miles per minute. it was felt from boston to cuba, and from eastern iowa to the bermudas, over a circular area whose diameter was a thousand miles. an earthquake is transmitted from the focus through the elastic rocks of the crust, as a wave, or series of waves, of compression and rarefaction, much as a sound wave is transmitted through the elastic medium of the air. each earth particle vibrates with exceeding swiftness, but over a very short path. the swing of a particle in firm rock seldom exceeds one tenth of an inch in ordinary earthquakes, and when it reaches one half an inch and an inch, the movement becomes dangerous and destructive. [illustration: fig. . block of the earth's crust shaken by an earthquake _x_, focus; _a_, _b_, _c_, _d_, successive spheroidal waves in the crust; _a´_, _b´_, _c´_, _d´_, successive surface waves produced by the outcropping of _a_, _b_, _c_, and _d_] the velocity of earthquake waves, like that of all elastic waves, varies with the temperature and elasticity of the medium. in the deep, hot, elastic rocks they speed faster than in the cold and broken rocks near the surface. the deeper the point of origin and the more violent the initial shock, the faster and farther do the vibrations run. great earthquakes, caused by some sudden displacement or some violent rending of the rocks, shake the entire planet. their waves run through the body of the earth at the rate of about three hundred and fifty miles a minute, and more slowly round its circumference, registering their arrival at opposite sides of the globe on the exceedingly delicate instruments of modern earthquake observatories. =geological effects.= even great earthquakes seldom produce geological effects of much importance. landslides may be shaken down from the sides of mountains and hills, and cracks may be opened in the surface deposits of plains; but the transient shiver, which may overturn cities and destroy thousands of human lives, runs through the crust and leaves it much the same as before. =earthquakes attending great displacements.= great earthquakes frequently attend the displacement of large masses of the rocks of the crust. in the coast of chile was suddenly raised three or four feet, and the rise was five or six feet a mile inland. in the same region was again upheaved from two to ten feet. in each instance a destructive earthquake was felt for one thousand miles along the coast. the great california earthquake of .= a sudden dislocation occurred in along an ancient fault plane which extends for miles through western california. the vertical displacement did not exceed four feet, while the horizontal shifting reached a maximum of twenty feet. fences, rows of trees, and roads which crossed the fault were broken and offset. the latitude and longitude of all points over thousands of square miles were changed. on each side of the fault the earth blocks moved in opposite directions, the block on the east moving southward and that on the west moving northward and to twice the distance. east and west of the fault the movements lessened with increasing distance from it. this sudden slip set up an earthquake lasting sixty-five seconds, followed by minor shocks recurring for many days. in places the jar shook down the waste on steep hillsides, snapped off or uprooted trees, and rocked houses from their foundations or threw down their walls or chimneys. the water mains of san francisco were broken, and the city was thus left defenseless against a conflagration which destroyed $ , , worth of property. the destructive effects varied with the nature of the ground. buildings on firm rock suffered least, while those on deep alluvium were severely shaken by the undulations, like water waves, into which the loose material was thrown. well-braced steel structures, even of the largest size, were earthquake proof, and buildings of other materials, when honestly built and intelligently designed to withstand earthquake shocks, usually suffered little injury. the length of the intervals between severe earthquakes in western california shows that a great dislocation so relieves the stresses of the adjacent earth blocks that scores of years may elapse before the stresses again accumulate and cause another dislocation. perhaps the most violent earthquake which ever visited the united states attended the depression, in , of a region seventy-five miles long and thirty miles wide, near new madrid, mo. much of the area was converted into swamps and some into shallow lakes, while a region twenty miles in diameter was bulged up athwart the channel of the mississippi. slight quakes are still felt in this region from time to time, showing that the strains to which the dislocation was due have not yet been fully relieved. =earthquakes originating beneath the sea.= many earthquakes originate beneath the sea, and in a number of examples they seem to have been accompanied, as soundings indicate, by local subsidences of the ocean bottom. there have been instances where the displacement has been sufficient to set the entire pacific ocean pulsating for many hours. in mid ocean the wave thus produced has a height of only a few feet, while it may be two hundred miles in width. on shores near the point of origin destructive waves two or three score feet in height roll in, and on coasts thousands of miles distant the expiring undulations may be still able to record themselves on tidal gauges. =distribution of earthquakes.= every half hour some considerable area of the earth's surface is sensibly shaken by an earthquake, but earthquakes are by no means uniformly distributed over the globe. as we might infer from what we know as to their causes, earthquakes are most frequent in regions now undergoing deformation. such are young rising mountain ranges, fault lines where readjustments recur from time to time, and the slopes of suboceanic depressions whose steepness suggests that subsidence may there be in progress. earthquakes, often of extreme severity, frequently visit the lofty and young ranges of the andes, while they are little known in the subdued old mountains of brazil. the highlands of scotland are crossed by a deep and singularly straight depression called the great glen, which has been excavated along a very ancient line of dislocation. the earthquakes which occur from time to time in this region, such as the inverness earthquake in , are referred to slight slips along this fault plane. in japan, earthquakes are very frequent. more than a thousand are recorded every year, and twenty-nine world-shaking earthquakes occurred in the three years ending with . they originate, for the most part, well down on the eastern flank of the earth fold whose summit is the mountainous crest of the islands, and which plunges steeply beneath the sea to the abyss of the tuscarora deep. =minor causes of earthquakes.= since any concussion within the crust sets up an earth jar, there are several minor causes of earthquakes, such as volcanic explosions and even the collapse of the roofs of caves. the earthquakes which attend the eruption of volcanoes are local, even in the case of the most violent volcanic paroxysms known. when the top of a volcano has been blown to fragments, the accompanying earth shock has sometimes not been felt more than twenty-five miles away. =depth of focus.= the focus of the charleston earthquake, estimated at about twelve miles below the surface, was exceptionally deep. volcanic earthquakes are particularly shallow, and probably no earthquakes known have started at a greater depth than fifteen or twenty miles. this distance is so slight compared with the earth's radius that we may say that earthquakes are but skin-deep. should you expect the velocity of an earthquake to be greater in a peneplain or in a river delta? after an earthquake, piles on which buildings rested were found driven into the ground, and chimneys crushed at base. from what direction did the shock come? chimneys standing on the south walls of houses toppled over on the roof. should you infer that the shock in this case came from the north or south? how should you expect a shock from the east to affect pictures hanging on the east and the west walls of a room? how the pictures hanging on the north and the south walls? in parts of the country, as in southwestern wisconsin, slender erosion pillars, or "monuments," are common. what inference could you draw as to the occurrence in such regions of severe earthquakes in the recent past? chapter xi volcanoes connected with movements of the earth's crust which take place so slowly that they can be inferred only from their effects is one of the most rapid and impressive of all geological processes,--the extrusion of molten rock from beneath the surface of the earth, giving rise to all the various phenomena of volcanoes. in a volcano, molten rock from a region deep below, which we may call its reservoir, ascends through a pipe or fissure to the surface. the materials erupted may be spread over vast areas, or, as is commonly the case, may accumulate about the opening, forming a conical pile known as the volcanic cone. it is to this cone that popular usage refers the word _volcano_; but the cone is simply a conspicuous part of the volcanic mechanism whose still more important parts, the reservoir and the pipe, are hidden from view. volcanic eruptions are of two types,--_effusive_ eruptions, in which molten rock wells up from below and flows forth in streams of _lava_ (a comprehensive term applied to all kinds of rock emitted from volcanoes in a molten state), and _explosive_ eruptions, in which the rock is blown out in fragments great and small by the expansive force of steam. eruptions of the effusive type =the hawaiian volcanoes.= the hawaiian islands are all volcanic in origin, and have a linear arrangement characteristic of many volcanic groups in all parts of the world. they are strung along a northwest-southeast line, their volcanoes standing in two parallel rows as if reared along two adjacent lines of fracture or folding. in the northwestern islands the volcanoes have long been extinct and are worn low by erosion. in the southeastern island. hawaii, three volcanoes are still active and in process of building. of these mauna loa, the monarch of volcanoes, with a girth of two hundred miles and a height of nearly fourteen thousand feet above sea level, is a lava dome the slope of whose sides does not average more than five degrees. on the summit is an elliptical basin ten miles in circumference and several hundred feet deep. concentric cracks surround the rim, and from time to time the basin is enlarged as great slices are detached from the vertical walls and engulfed. such a volcanic basin, formed by the insinking of the top of the cone, is called a _caldera_. [illustration: fig. . mauna loa] [illustration: fig. . caldera of mauna loa] on the flanks of mauna loa, four thousand feet above sea level, lies the caldera of kilauea, an independent volcano whose dome has been joined to the larger mountain by the gradual growth of the two. in each caldera the floor, which to the eye is a plain of black lava, is the congealed surface of a column of molten rock. at times of an eruption lakes of boiling lava appear which may be compared to air holes in a frozen river. great waves surge up, lifting tons of the fiery liquid a score of feet in air, to fall back with a mighty plunge and roar, and occasionally the lava rises several hundred feet in fountains of dazzling brightness. the lava lakes may flood the floor of the basin, but in historic times have never been known to fill it and overflow the rim. instead, the heavy column of lava breaks way through the sides of the mountain and discharges in streams which flow down the mountain slopes for a distance sometimes of as much as thirty-five miles. with the drawing off of the lava the column in the duct of the volcano lowers, and the floor of the caldera wholly or in part subsides. a black and steaming abyss marks the place of the lava lakes (fig. ). after a time the lava rises in the duct, the floor is floated higher, and the boiling lakes reappear. [illustration: fig. . portion of caldera of kilauea after collapse following an eruption] the eruptions of the hawaiian volcanoes are thus of the effusive type. the column of lava rises, breaks through the side of the mountain, and discharges in lava streams. there are no explosions, and usually no earthquakes, or very slight ones, accompany the eruptions. the lava in the calderas boils because of escaping steam, but the vapor emitted is comparatively little, and seldom hangs above the summits in heavy clouds. we see here in its simplest form the most impressive and important fact in all volcanic action, molten rock has been driven upward to the surface from some deep-lying source. =lava flows.= as lava issues from the side of a volcano or overflows from the summit, it flows away in a glowing stream resembling molten iron drawn white-hot from an iron furnace. the surface of the stream soon cools and blackens, and the hard crust of nonconducting rock may grow thick and firm enough to form a tunnel, within which the fluid lava may flow far before it loses its heat to any marked degree. such tunnels may at last be left as caves by the draining away of the lava, and are sometimes several miles in length. [illustration: fig. . pahoehoe lava, hawaii] =pahoehoe and aa.= when the crust of highly fluid lava remains unbroken after its first freezing, it presents a smooth, hummocky, and ropy surface known by the hawaiian term _pahoehoe_ (fig. ). on the other hand, the crust of a viscid flow may be broken and splintered as it is dragged along by the slowly moving mass beneath. the stream then appears as a field of stones clanking and grinding on, with here and there from some chink a dull red glow or a wisp of steam. it sets to a surface called _aa_, of broken, sharp-edged blocks, which is often both difficult and dangerous to traverse (fig. ). [illustration: fig. . lava flow of the _aa_ type, cinder cones in the distance, arizona] =fissure eruptions.= some of the largest and most important outflows of lava have not been connected with volcanic cones, but have been discharged from fissures, flooding the country far and wide with molten rock. sheet after sheet of molten rock has been successively outpoured, and there have been built up, layer upon layer, plateaus of lava thousands of feet in thickness and many thousands of square miles in area. =iceland.= this island plateau has been rent from time to time by fissures from which floods of lava have outpoured. in some instances the lava discharges along the whole length of the fissure, but more often only at certain points upon it. the laki fissure, twenty miles long, was in eruption in for seven months. the inundation of fluid rock which poured from it is the largest of historic record, reaching a distance of forty-seven miles and covering two hundred and twenty square miles to an average depth of a hundred feet. at the present time the fissure is traced by a line of several hundred insignificant mounds of fragmental materials which mark where the lava issued (fig. ). the distance to which the fissure eruptions of iceland flow on slopes extremely gentle is noteworthy. one such stream is ninety miles in length, and another seventy miles long has a slope of little more than one half a degree. where lava is emitted at one point and flows to a less distance there is gradually built up a dome of the shape of an inverted saucer with an immense base but comparatively low. many _lava domes_ have been discovered in iceland, although from their exceedingly gentle slopes, often but two or three degrees, they long escaped the notice of explorers. the entire plateau of iceland, a region as large as ohio, is composed of volcanic products,--for the most part of successive sheets of lava whose total thickness falls little short of two miles. the lava sheets exposed to view were outpoured in open air and not beneath the sea; for peat bogs and old forest grounds are interbedded with them, and the fossil plants of these vegetable deposits prove that the plateau has long been building and is very ancient. on the steep sea cliffs of the island, where its structure is exhibited, the sheets of lava are seen to be cut with many _dikes_,--fissures which have been filled by molten rock,--and there is little doubt that it was through these fissures that the lava outwelled in successive flows which spread far and wide over the country and gradually reared the enormous pile of the plateau. eruptions of the explosive type in the majority of volcanoes the lava which rises in the pipe is at least in part blown into fragments with violent explosions and shot into the air together with vast quantities of water vapor and various gases. the finer particles into--which the lava is exploded are called _volcanic dust_ or _volcanic ashes_, and are often carried long distances by the wind before they settle to the earth. the coarser fragments fall about the vent and there accumulate in a steep, conical, volcanic mountain. as successive explosions keep open the throat of the pipe, there remains on the summit a cup-shaped depression called the _crater_. =stromboli.= to study the nature of these explosions we may visit stromboli, a low volcano built chiefly of fragmental materials, which rises from the sea off the north coast of sicily and is in constant though moderate action. over the summit hangs a cloud of vapor which strikingly resembles the column of smoke puffed from the smokestack of a locomotive, in that it consists of globular masses, each the product of a distinct explosion. at night the cloud of vapor is lighted with a red glow at intervals of a few minutes, like the glow on the trail of smoke behind the locomotive when from time to time the fire box is opened. because of this intermittent light flashing thousands of feet above the sea, stromboli has been given the name of the lighthouse of the mediterranean. looking down into the crater of the volcano, one sees a viscid lava slowly seething. the agitation gradually increases. a great bubble forms. it bursts with an explosion which causes the walls of the crater to quiver with a miniature earthquake, and an outrush of steam carries the fragments of the bubble aloft for a thousand feet to fall into the crater or on the mountain side about it. with the explosion the cooled and darkened crust of the lava is removed, and the light of the incandescent liquid beneath is reflected from the cloud of vapor which overhangs the cone. at stromboli we learn the lesson that the explosive force in volcanoes is that of steam. the lava in the pipe is permeated with it much as is a thick boiling porridge. the steam in boiling porridge is unable to escape freely and gathers into bubbles which in breaking spurt out drops of the pasty substance; in the same way the explosion of great bubbles of steam in the viscid lava shoots clots and fragments of it into the air. =krakatoa.= the most violent eruption of history, that of krakatoa, a small volcanic island in the strait between sumatra and java, occurred in the last week of august, . continuous explosions shot a column of steam and ashes. seventeen miles in air. a black cloud, beneath which was midnight darkness and from which fell a rain of ashes and stones, overspread the surrounding region to a distance of one hundred and fifty miles. launched on the currents of the upper air, the dust was swiftly carried westward to long distances. three days after the eruption it fell on the deck of a ship sixteen hundred miles away, and in thirteen days the finest impalpable powder from the volcano had floated round the globe. for many months the dust hung over europe and america as a faint lofty haze illuminated at sunrise and sunset with brilliant crimson. in countries nearer the eruption, as in india and africa, the haze for some time was so thick that it colored sun and moon with blue, green, and copper-red tints and encircled them with coronas. at a distance of even a thousand miles the detonations of the eruption sounded like the booming of heavy guns a few miles away. in one direction they were audible for a distance as great as that from san francisco to cleveland. the entire atmosphere was thrown into undulations under which all barometers rose and fell as the air waves thrice encircled the earth. the shock of the explosions raised sea waves which swept round the adjacent shores at a height of more than fifty feet, and which were perceptible halfway around the globe. at the close of the eruption it was found that half the mountain had been blown away, and that where the central part of the island had been the sea was a thousand feet deep. =martinique and st. vincent.= in two dormant volcanoes of the west indies, mt. pelee in martinique and soufrière in st. vincent, broke into eruption simultaneously. no lava was emitted, but there were blown into the air great quantities of ashes, which mantled the adjacent parts of the islands with a pall as of gray snow. in early stages of the eruption lakes which occupied old craters were discharged and swept down the ash-covered mountain valleys in torrents of boiling mud. on several occasions there was shot from the crater of each volcano a thick and heavy cloud of incandescent ashes and steam, which rushed down the mountain side like an avalanche, red with glowing stones and scintillating with lightning flashes. forests and buildings in its path were leveled as by a tornado, wood was charred and set on fire by the incandescent fragments, all vegetation was destroyed, and to breathe the steam and hot, suffocating dust of the cloud was death to every living creature. on the morning of the th of may, , the first of these peculiar avalanches from mt. pelee fell on the city of st. pierre and instantly destroyed the lives of its thirty thousand inhabitants. [illustration: fig. . an eruption of vesuvius, ] the eruptions of many volcanoes partake of both the effusive and the explosive types: the molten rock in the pipe is in part blown into the air with explosions of steam, and in part is discharged in streams of lava over the lip of the crater and from fissures in the sides of the cone. such are the eruptions of vesuvius, one of which is illustrated in figure . =submarine eruptions.= the many volcanic islands of the ocean and the coral islands resting on submerged volcanic peaks prove that eruptions have often taken place upon the ocean floor and have there built up enormous piles of volcanic fragments and lava. the hawaiian volcanoes rise from a depth of eighteen thousand feet of water and lift their heads to about thirty thousand feet above the ocean bed. christmas island (see p. ), built wholly beneath the ocean, is a coral-capped volcanic peak, whose total height, as measured from the bottom of the sea, is more than fifteen thousand feet. deep-sea soundings have revealed the presence of numerous peaks which fail to reach sea level and which no doubt are submarine volcanoes. a number of volcanoes on the land were submarine in their early stages, as, for example, the vast pile of etna, the celebrated sicilian volcano, which rests on stratified volcanic fragments containing marine shells now uplifted from the sea. submarine outflows of lava and deposits of volcanic fragments become covered with sediments during the long intervals between eruptions. such volcanic deposits are said to be _contemporaneous_, because they are formed during the same period as the strata among which they are imbedded. contemporaneous lava sheets may be expected to bake the surface of the stratum on which they rest, while the sediments deposited upon them are unaltered by their heat. they are among the most permanent records of volcanic action, far outlasting the greatest volcanic mountains built in open air. from upraised submarine volcanoes, such as christmas island, it is learned that lava flows which are poured out upon the bottom of the sea do not differ materially either in composition or texture from those of the land. volcanic products vast amounts of steam are, as we have seen, emitted from volcanoes, and comparatively small quantities of other vapors, such as various acid and sulphurous gases. the rocks erupted from volcanoes differ widely in chemical composition and in texture. [illustration: fig. . cellular lava] =acidic and basic lavas.= two classes of volcanic rocks may be distinguished,--those containing a large proportion of silica (silicic acid, sio_{ }) and therefore called _acidic_, and those containing less silica and a larger proportion of the bases (lime, magnesia, soda, etc.) and therefore called _basic_. the acidic lavas, of which _rhyolite_ and _thrachyte_ are examples, are comparatively light in color and weight, and are difficult to melt. the basic lavas, of which _basalt_ is a type, are dark and heavy and melt at a lower temperature. =scoria and pumice.= the texture of volcanic rocks depends in part on the degree to which they were distended by the steam which permeated them when in a molten state. they harden into compact rock where the steam cannot expand. where the steam is released from pressure, as on the surface of a lava stream, it forms bubbles (steam blebs) of various sizes, which give the hardened rock a cellular structure (fig. ), in this way are formed the rough slags and clinkers called _scoria_, which are found on the surface of flows and which are also thrown out as clots of lava in explosive eruptions. on the surface of the seething lava in the throat of the volcano there gathers a rock foam, which, when hurled into the air, is cooled and falls as _pumice_,--a spongy gray rock so light that it floats on water. [illustration: fig. . amygdules in lava] =amygdules.= the steam blebs of lava flows are often drawn out from a spherical to an elliptical form resembling that of an almond, and after the rock has cooled these cavities are gradually filled with minerals deposited from solution by underground water. from their shape such casts are called amygdules (greek, _amygdalon_, an almond). amygdules are commonly composed of silica. lavas contain both silica and the alkalies, potash and soda, and after dissolving the alkalies, percolating water is able to take silica also into solution. most _agates_ are banded amygdules in which the silica has been laid in varicolored, concentric layers (fig. ). [illustration: fig. . polished section of an agate] [illustration: fig. . microsection showing the beginnings of crystal growth in glassy lava] =glassy and stony lavas.= volcanic rocks differ in texture according also to the rate at which they have solidified. when rapidly cooled, as on the surface of a lava flow, molten rock chills to a glass, because the minerals of which it is composed have not had time to separate themselves from the fused mixture and form crystals. under slow cooling, as in the interior of the flow, it becomes a stony mass composed of crystals set in a glassy paste. in thin slices of volcanic glass one may see under the microscope the beginnings of crystal growth in filaments and needles and feathery forms, which are the rudiments of the crystals of various minerals. spherulites, which also mark the first changes of glassy lavas toward a stony condition, are little balls within the rock, varying from microscopic size to several inches in diameter, and made up of radiating fibers. perlitic structure, common among glassy lavas, consists of microscopic curving and interlacing cracks, due to contraction. [illustration: fig. . perlitic structure and spherulites, _a_, _a_] [illustration: fig. . flow lines in lava] =flow lines= are exhibited by volcanic rocks both to the naked eye and under the microscope. steam blebs, together with crystals and their embryonic forms, are left arranged in lines and streaks by the currents of the flowing lava as it stiffened into rock. [illustration: fig. . porphyritic structure] =porphyritic structure.= rocks whose ground mass has scattered through it large conspicuous crystals (fig. ) are said to be _porphyritic_, and it is especially among volcanic rocks that this structure occurs. the ground mass of porphyries either may be glassy or may consist in part of a felt of minute crystals; in either case it represents the consolidation of the rock after its outpouring upon the surface. on the other hand, the large crystals of porphyry have slowly formed deep below the ground at an earlier date. =columnar structure.= just as wet starch contracts on drying to prismatic forms, so lava often contracts on cooling to a mass of close-set, prismatic, and commonly six-sided columns, which stand at right angles to the cooling surface. the upper portion of a flow, on rapid cooling from the surface exposed to the air, may contract to a confused mass of small and irregular prisms; while the remainder forms large and beautifully regular columns, which have grown upward by slow cooling from beneath (fig. ). fragmental materials rocks weighing many tons are often thrown from a volcano at the beginning of an outburst by the breaking up of the solidified floor of the crater; and during the progress of an eruption large blocks may be torn from the throat of the volcano by the outrush of steam. but the most important fragmental materials are those derived from the lava itself. as lava rises in the pipe, the steam which permeates it is released from pressure and explodes, hurling the lava into the air in fragments of all sizes,--large pieces of scoria, _lapilli_ (fragments the size of a pea or walnut), volcanic "sand" and volcanic "ashes." the latter resemble in appearance the ashes of wood or coal, but they are not in any sense, like them, a residue after combustion. [illustration: fig. . columnar structure in basaltic lava, scotland] volcanic ashes are produced in several ways: lava rising in the volcanic duct is exploded into fine dust by the steam which permeates it; glassy lava, hurled into the air and cooled suddenly, is brought into a state of high strain and tension, and, like prince rupert's drops, flies to pieces at the least provocation. the clash of rising and falling projectiles also produces some dust, a fair sample of which may be made by grating together two pieces of pumice. beds of volcanic ash occur widely among recent deposits in the western united states. in nebraska ash beds are found in twenty counties, and are often as white as powdered pumice. the beds grow thicker and coarser toward the southwestern part of the state, where their thickness sometimes reaches fifty feet. in what direction would you look for the now extinct volcano whose explosive eruptions are thus recorded? =tuff.= this is a convenient term designating any rock composed of volcanic fragments. coarse tuffs of angular fragments are called _volcanic breccia_, and when the fragments have been rounded and sorted by water the rock is termed a _volcanic conglomerate_. even when deposited in the open air, as on the slopes of a volcano, tuffs may be rudely bedded and their fragments more or less rounded, and unless marine shells or the remains of land plants and animals are found as fossils in them, there is often considerable difficulty in telling whether they were laid in water or in air. in either case they soon become consolidated. chemical deposits from percolating waters fill the interstices, and the bed of loose fragments is cemented to hard rock. the materials of which tuffs are composed are easily recognized as volcanic in their origin. the fragments are more or less cellular, according to the degree to which they were distended with steam when in a molten state, and even in the finest dust one may see the glass or the crystals of lava from which it was derived. tuffs often contain _volcanic bombs_,--balls of lava which took shape while whirling in the air, and solidified before falling to the ground. [illustration: fig. . volcanic bombs, cinder cone, california] [illustration: fig. . a volcanic cone, arizona] =ancient volcanic rocks.= it is in these materials and structures which we have described that volcanoes leave some of their most enduring records. even the volcanic rocks of the earliest geological ages, uplifted after long burial beneath the sea and exposed to view by deep erosion, are recognized and their history read despite the many changes which they may have undergone. a sheet of ancient lava may be distinguished by its composition from the sediments among which it is imbedded. the direction of its flow lines may be noted. the cellular and slaggy surface where the pasty lava was distended by escaping steam is recognized by the amygdules which now fill the ancient steam blebs. in a pile of successive sheets of lava each flow may be distinguished and its thickness measured; for the surface of each sheet is glassy and scoriaceous, while beneath its upper portions the lava of each flow is more dense and stony. the length of time which elapsed before a sheet was buried beneath the materials of succeeding eruptions may be told by the amount of weathering which it had undergone, the depth of ancient soil--now baked to solid rock--upon it, and the erosion which it had suffered in the interval. if the flow occurred from some submarine volcano, we may recognize the fact by the sea-laid sediments which cover it, filling the cracks and crevices of its upper surface and containing pieces of lava washed from it in their basal layers. long-buried glassy lavas devitrify, or pass to a stony condition, under the unceasing action of underground waters; but their flow lines and perlitic and spherulitic structures remain to tell of their original state. ancient tuffs are known by the fragmental character of their volcanic material, even though they have been altered to firm rock. some remains of land animals and plants may be found imbedded to tell that the beds were laid in open air; while the remains of marine organisms would prove as surely that the tuffs were deposited in the sea. in these ways ancient volcanoes have been recognized near boston, in southeastern pennsylvania, about lake superior, and in other regions of the united states. the life history of a volcano the invasion of a region by volcanic forces is attended by movements of the crust heralded by earthquakes. a fissure or a pipe is opened and the building of the cone or the spreading of wide lava sheets is begun. =volcanic cones.= the shape of a volcanic cone depends chiefly on the materials erupted. cones made of fragments may have sides as steep as the angle of repose, which in the case of coarse scoria is sometimes as high as thirty or forty degrees. about the base of the mountain the finer materials erupted are spread in more gentle slopes, and are also washed forward by rains and streams. the normal profile is thus a symmetric cone with a flaring base. [illustration: fig. . sarcoui, a trachyte dome, france] cones built of lava vary in form according to the liquidity of the lava. domes of gentle slope, as those of hawaii, for example, are formed of basalt, which flows to long distances before it congeals. when superheated and emitted from many vents, this easily melted lava builds great plateaus, such as that of iceland. on the other hand, lavas less fusible, or poured out at a lower temperature, stiffen when they have flowed but a short distance, and accumulate in a steep cone. trachyte has been extruded in a state so viscid that it has formed steep-sided domes like that of sarcoui (fig. ). most volcanoes are built, like vesuvius, both of lava flows and of tuffs, and sections show that the structure of the cone consists of outward-dipping, alternating layers of lava, scoria, and ashes. [illustration: fig. . section of vesuvius _v_, vesuvius; _s_, somma, a mountainous rampart half encircling vesuvius, and like it built of outward-dipping sheets of tuff and lava; _a_, crystalline rocks; _b_, marine strata; _c_, tuffs containing seashells. which is the older mountain, vesuvius or somma? of what is somma a remnant? draw a diagram showing its original outline. suggest what processes may have brought it to its present form. what record do you find of the earliest volcanic activity? what do you infer as to the beginnings of the volcano?] from time to time the cone is rent by the violence of explosions and by the weight of the column of lava in the pipe. the fissures are filled with lava and some discharge on the sides of the mountain, building parasitic cones, while all form dikes, which strengthen the pile with ribs of hard rock and make it more difficult to rend. great catastrophes are recorded in the shape of some volcanoes which consist of a circular rim perhaps miles in diameter, inclosing a vast crater or a caldera within which small cones may rise. we may infer that at some time the top of the mountain has been blown off, or has collapsed and been engulfed because some reservoir beneath had been emptied by long-continued eruptions (fig. ). the cone-building stage may be said to continue until eruptions of lava and fragmental materials cease altogether. sooner or later the volcanic forces shift or die away, and no further eruptions add to the pile or replace its losses by erosion during periods of repose. gases however are still emitted, and, as sulphur vapors are conspicuous among them, such vents are called _solfataras_. mount hood, in oregon, is an example of a volcano sunk to this stage. from a steaming rift on its side there rise sulphurous fumes which, half a mile down the wind, will tarnish a silver coin. [illustration: fig. . crater lake, oregon how wide and deep is the basin which holds the lake? the mountain walls which enclose it are made of outward-dipping sheets of lava. draw a diagram restoring the volcano of which they are the remnant. no volcanic fragments of the same nature as the materials of which the volcano is built are found about the region. what theory of the destruction of the cone does this fact favor? _w´_, wizard island, is a cinder cone. when was it built?] =geysers and hot springs.= the hot springs of volcanic regions are among the last vestiges of volcanic heat. periodically eruptive boiling springs are termed geysers. in each of the geyser regions of the earth--the yellowstone national park, iceland, and new zealand--the ground water of the locality is supposed to be heated by ancient lavas that, because of the poor conductivity of the rock, still remain hot beneath the surface. [illustration: fig. . old faithful geyser in eruption, yellowstone national park] =old faithful=, one of the many geysers of the yellowstone national park, plays a fountain of boiling water a hundred feet in air; while clouds of vapor from the escaping steam ascend to several times that height. the eruptions take place at intervals of from seventy to ninety minutes. in repose the geyser is a quiet pool, occupying a craterlike depression in a conical mound some twelve feet high. the conduit of the spring is too irregular to be sounded. the mound is composed of porous silica deposited by the waters of the geyser. geysers erupt at intervals instead of continuously boiling, because their long, narrow, and often tortuous conduits do not permit a free circulation of the water. after an eruption the tube is refilled and the water again gradually becomes heated. deep in the tube where it is in contact with hot lavas the water sooner or later reaches the boiling point, and bursting into steam shoots the water above it high in air. [illustration: fig. . terrace and cones of siliceous sinter deposited by geysers, yellowstone national park] =carbonated springs.= after all the other signs of life have gone, the ancient volcano may emit carbon dioxide as its dying breath. the springs of the region may long be charged with carbon dioxide, or carbonated, and where they rise through limestone may be expected to deposit large quantities of travertine. we should remember, however, that many carbonated springs, and many hot springs, are wholly independent of volcanoes. [illustration: fig. . mount shasta, california] [illustration: fig. . mount hood, oregon] =the destruction of the cone.= as soon as the volcanic cone ceases to grow by eruptions the agents of erosion begin to wear it down, and the length of time that has elapsed since the period of active growth may be roughly measured by the degree to which the cone has been dissected. we infer that mount shasta, whose conical shape is still preserved despite the gullies one thousand feet deep which trench its sides (fig. ), is younger than mount hood, which erosive agencies have carved to a pyramidal form (fig. ). the pile of materials accumulated about a volcanic vent, no matter how vast in bulk, is at last swept entirely away. the cone of the volcano, active or extinct, is not old as the earth counts time; volcanoes are short-lived geological phenomena. [illustration: fig. . crandall volcano] =crandall volcano.= this name is given to a dissected ancient volcano in the yellowstone national park, which once, it is estimated, reared its head thousands of feet above the surrounding country and greatly exceeded in bulk either mount shasta or mount etna. not a line of the original mountain remains; all has been swept away by erosion except some four thousand feet of the base of the pile. this basal wreck now appears as a rugged region about thirty miles in diameter, trenched by deep valleys and cut into sharp peaks and precipitous ridges. in the center of the area is found the nucleus (_n_, fig. ),--a mass of coarsely crystalline rock that congealed deep in the old volcanic pipe. from it there radiate in all directions, like the spokes of a wheel, long dikes whose rock grows rapidly finer of grain as it leaves the vicinity of the once heated core. the remainder of the base of the ancient mountain is made of rudely bedded tuffs and volcanic breccia, with occasional flows of lava, some of the fragments of the breccia measuring as much as twenty feet in diameter. on the sides of canyons the breccia is carved by rain erosion to fantastic pinnacles. at different levels in the midst of these beds of tuff and lava are many old forest grounds. the stumps and trunks of the trees, now turned to stone, still in many cases stand upright where once they grew on the slopes of the mountain as it was building (fig. ). the great size and age of some of these trees indicate, the lapse of time between the eruption whose lavas or tuffs weathered to the soil on which they grew and the subsequent eruption which buried them beneath showers of stones and ashes. near the edge of the area lies death gulch, in which carbon dioxide is given off in such quantities that in quiet weather it accumulates in a heavy layer along the ground and suffocates the animals which may enter it. [illustration: fig. . fossil tree trunks, yellowstone national park] chapter xii underground structures of igneous origin it is because long-continued erosion lays bare the innermost anatomy of an extinct volcano, and even sweeps away the entire pile with much of the underlying strata, thus leaving the very roots of the volcano open to view, that we are able to study underground volcanic structures. with these we include, for convenience, intrusions of molten rock which have been driven upward into the crust, but which may not have succeeded in breaking way to the surface and establishing a volcano. all these structures are built of rock forced when in a fluid or pasty state into some cavity which it has found or made, and we may classify them therefore, according to the shape of the molds in which the molten rock has congealed, as ( ) dikes, ( ) volcanic necks, ( ) intrusive sheets, and ( ) intrusive masses. =dikes.= the sheet of once molten rock with which a fissure has been filled is known as a dike. dikes are formed when volcanic cones are rent by explosions or by the weight of the lava column in the duct, and on the dissection of the pile they appear as radiating vertical ribs cutting across the layers of lava and tuff of which the cone is built. in regions undergoing deformation rocks lying deep below the ground are often broken and the fissures are filled with molten rock from beneath, which finds no outlet to the surface. such dikes are common in areas of the most ancient rocks, which have been brought to light by long erosion. in exceptional cases dikes may reach the length of fifty or one hundred miles. they vary in width from a fraction of a foot to even as much as three hundred feet. [illustration: fig. . dikes, spanish peaks, colorado] dikes are commonly more fine of grain on the sides than in the center, and may have a glassy and crackled surface where they meet the inclosing rock. can you account for this on any principle which you have learned? [illustration: fig. . a dissected volcanic cone _n_, volcanic neck; _l_, _l_, lava-topped table mountains; _t_, _t_, beds of tuff; _d_, _d_, dikes; dotted lines indicate the initial profile] =volcanic necks.= the pipe of a volcano rises from far below the base of the cone,--from the deep reservoir from which its eruptions are supplied. when the volcano has become extinct this great tube remains filled with hardened lava. it forms a cylindrical core of solid rock, except for some distance below the ancient crater, where it may contain a mass of fragments which had fallen back into the chimney after being hurled into the air. [illustration: fig. . mount johnson, a volcanic neck near montreal] as the mountain is worn down, this central column known as the _volcanic neck_ is left standing as a conical hill (fig. ). even when every other trace of the volcano has been swept away, erosion will not have passed below this great stalk on which the volcano was borne as a fiery flower whose site it remains to mark. in volcanic regions of deep denudation volcanic necks rise solitary and abrupt from the surrounding country as dome-shaped hills. they are marked features in the landscape in parts of scotland and in the st. lawrence valley about montreal (fig. ). [illustration: fig. . the palisades of the hudson, new jersey] =intrusive sheets.= sheets of igneous rocks are sometimes found interleaved with sedimentary strata, especially in regions where the rocks have been deformed and have suffered from volcanic action. in some instances such a sheet is seen to be _contemporaneous_ (p. ). in other instances the sheet must be _intrusive_. the overlying stratum, as well as that beneath, has been affected by the heat of the once molten rock. we infer that the igneous rock when in a molten state was forced between the strata, much as a card may be pushed between the leaves of a closed book. the liquid wedged its way between the layers, lifting those above to make room for itself. the source of the intrusive sheet may often be traced to some dike (known therefore as the _feeding dike_), or to some mass of igneous rock. intrusive sheets may extend a score and more of miles, and, like the longest surface flows, the most extensive sheets consist of the more fusible and fluid lavas,--those of the basic class of which basalt is an example. intrusive sheets are usually harder than the strata in which they lie and are therefore often left in relief after long denudation of the region (fig. ). [illustration: fig. . diagram of the palisades of the hudson _i_, intrusive sheet; _s_, sandstone; _d_, feeding dike; _hr_, hudson river] on the west bank of the hudson there extends from new york bay north for thirty miles a bold cliff several hundred feet high,--the _palisades of the hudson_. it is the outcropping edge of a sheet of ancient igneous rock, which rests on stratified sandstones and is overlain by strata of the same series. sandstones and lava sheet together dip gently to the west and the latter disappears from view two miles back from the river. it is an interesting question whether the palisades sheet is _contemporaneous_ or _intrusive_. was it outpoured on the sandstones beneath it when they formed the floor of the sea, and covered forthwith by the sediments of the strata above, or was it intruded among these beds at a later date? [illustration: fig. . section of electric peak. e. and gray peak, g, yellowstone national park intrusive sheets and masses of igneous rock are drawn in black] the latter is the case: for the overlying stratum is intensely baked along the zone of contact. at the west edge of the sheet is found the dike in which the lava rose to force its way far and wide between the strata. _electric peak_, one of the prominent mountains of the yellowstone national park, is carved out of a mass of strata into which many sheets of molten rock have been intruded. the western summit consists of such a sheet several hundred feet thick. studying the section of figure , what inference do you draw as to the source of these intrusive sheets? [illustration: fig. . stone mountain, georgia, a granite boss] intrusive masses =bosses.= this name is generally applied to huge irregular masses of coarsely crystalline igneous rock lying in the midst of other formations. bosses vary greatly in size and may reach scores of miles in extent. seldom are there any evidences found that bosses ever had connection with the surface. on the other hand, it is often proved that they have been driven, or have melted their way, upward into the formations in which they lie; for they give off dikes and intrusive sheets, and have profoundly altered the rocks about them by their heat. [illustration: fig. . map of granite bosses near baltimore (areas horizontally lined) the texture of the rock of bosses proves that consolidation proceeded slowly and at great depths, and it is only because of vast denudation that they are now exposed to view. bosses are commonly harder than the rocks about them, and stand up, therefore, as rounded hills and mountainous ridges long after the surrounding country has worn to a low plain (fig. ). figure exhibits a few small bosses of granite near baltimore as examples of numerous areas of igneous rock within the piedmont belt which represent bodies of molten rock which solidified deep below the surface. the _spanish peaks_ of southeastern colorado were formed by the upthrust of immense masses of igneous rock, bulging and breaking the overlying strata. on one side of the mountains the throw of the fault is nearly a mile, and fragments of deep-lying beds were dragged upward by the rising masses. the adjacent rocks were altered by heat to a distance of several thousand feet. no evidence appears that the molten rock ever reached the surface, and if volcanic eruptions ever took place either in lava flows or fragmental materials, all traces of them have been effaced. the rock of the intrusive masses is coarsely crystalline, and no doubt solidified slowly under the pressure of vast thicknesses of overlying rock, now mostly removed by erosion. a magnificent system of dikes radiates from the peaks to a distance of fifteen miles, some now being left by long erosion as walls a hundred feet in height (fig. ). intrusive sheets fed by the dikes penetrate the surrounding strata, and their edges are cut by canyons as much as twenty-five miles from the mountain. in these strata are valuable beds of lignite, an imperfect coal, which the heat of dikes and sheets has changed to coke. [illustration: fig. . section of a laccolith] =laccoliths.= the laccolith (greek laccos, cistern; lithos, stone) is a variety of intrusive masses in which molten rock has spread between the strata, and, lifting the strata above it to a dome-shaped form, has collected beneath them in a lens-shaped body with a flat base. the _henry mountains_, a small group of detached peaks in southern utah, rise from a plateau of horizontal rocks. some of the peaks are carved wholly in separate domelike uplifts of the strata of the plateau. in others, as mount hillers, the largest of the group, there is exposed on the summit a core of igneous rock from which the sedimentary rocks of the flanks dip steeply outward in all directions. in still others erosion has stripped off the covering strata and has laid bare the core to its base; and its shape is here seen to be that of a plano-convex lens or a baker's bun, its flat base resting on the undisturbed bedded rocks beneath. the structure of mount hillers is shown in figure . the nucleus of igneous rock is four miles in diameter and more than a mile in depth. [illustration: fig. . section of mount hillers] =regional intrusions.= these vast bodies of igneous rock, which may reach hundreds of miles in diameter, differ little from bosses except in their immense bulk. like bosses, regional intrusions give off dikes and sheets and greatly change the rocks about them by their heat. they are now exposed to view only because of the profound denudation which has removed the upheaved dome of rocks beneath which they slowly cooled. such intrusions are accompanied--whether as cause or as effect is still hardly known--by deformations, and their masses of igneous rock are thus found as the core of many great mountain ranges. the granitic masses of which the bitter root mountains and the sierra nevadas have been largely carved are each more than three hundred miles in length. immense regional intrusions, the cores of once lofty mountain ranges, are found upon the laurentian peneplain. =physiographic effects of intrusive masses.= we have already seen examples of the topographic effects of intrusive masses in mount hillers, the spanish peaks, and in the great mountain ranges mentioned in the paragraph on regional intrusions, although in the latter instances these effects are entangled with the effects of other processes. masses of igneous rock cannot be intruded within the crust without an accompanying deformation on a scale corresponding to the bulk of the intruded mass. the overlying strata are arched into hills or mountains, or, if the molten material is of great extent, the strata may conceivably be floated upward to the height of a plateau. we may suppose that the transference of molten matter from one region to another may be among the causes of slow subsidences and elevations. intrusions give rise to fissures, dikes, and intrusive sheets, and these dislocations cannot fail to produce earthquakes. where intrusive masses open communication with the surface, volcanoes are established or fissure eruptions occur such as those of iceland. the intrusive rocks the igneous rocks are divided into two general classes,--the _volcanic_ or _eruptive_ rocks, which have been outpoured in open air or on the floor of the sea, and the _intrusive_ rocks, which have been intruded within the rocks of the crust and have solidified below the surface. the two classes are alike in chemical composition and may be divided into acidic and basic groups. in texture the intrusive rocks differ from the volcanic rocks because of the different conditions under which they have solidified. they cooled far more slowly beneath the cover of the rocks into which they were pressed than is permitted to lava flows in open air. their constituent minerals had ample opportunity to sort themselves and crystallize from the fluid mixture, and none of that mixture was left to congeal as a glassy paste. they consolidated also under pressure. they are never scoriaceous, for the steam with which they were charged was not allowed to expand and distend them with steam blebs. in the rocks of the larger intrusive masses one may see with a powerful microscope exceedingly minute cavities, to be counted by many millions to the cubic inch, in which the gaseous water which the mass contained was held imprisoned under the immense pressure of the overlying rocks. naturally these characteristics are best developed in the intrusives which cooled most slowly, i.e. in the deepest-seated and largest masses; while in those which cooled more rapidly, as in dikes and sheets, we find gradations approaching the texture of surface flows. =varieties of the intrusive rocks.= we will now describe a few of the varieties of rocks of deep-seated intrusions. all are even grained, consisting of a mass of crystalline grains formed during one continuous stage of solidification, and no porphyritic crystals appear as in lavas. _granite_, as we have learned already, is composed of three minerals,--quartz, feldspar, and mica. according to the color of the feldspar the rock may be red, or pink, or gray. hornblende--a black or dark green mineral, an iron-magnesian silicate, about as hard as feldspar--is sometimes found as a fourth constituent, and the rock is then known as _hornblendic granite_. granite is an acidic rock corresponding to rhyolite in chemical composition. we may believe that the same molten mass which supplies this acidic lava in surface flows solidifies as granite deep below ground in the volcanic reservoir. _syenite_, composed of feldspar and mica, has consolidated from a less siliceous mixture than has granite. _diorite_, still less siliceous, is composed of hornblende and feldspar,--the latter mineral being of different variety from the feldspar of granite and syenite. _gabbro_, a typical basic rock, corresponds to basalt in chemical composition. it is a dark, heavy, coarsely crystalline aggregate of feldspar and _augite_ (a dark mineral allied to hornblende). it often contains _magnetite_ (the magnetic black oxide of iron) and _olivine_ (a greenish magnesian silicate). in the northern states all these types, and many others also of the vast number of varieties of intrusive rocks, can be found among the rocks of the drift brought from the areas of igneous rock in canada and the states of our northern border. [illustration: fig. . ground plan of dikes in granite. (scale feet to the inch) what is the relative age of the dikes _aa_, _bb_, and _cc_?] [illustration: fig. . _a_ and _b_. mountains of coarsely crystalline igneous _i_, surrounded by sedimentary strata _s_ and _s´_ copy each diagram and complete it, so as to show whether the mass of igneous rock is a volcanic neck, a boss, or a laccolith] =summary.= the records of geology prove that since the earliest of their annals tremendous forces have been active in the earth. in all the past, under pressures inconceivably great, molten rock has been driven upward into the rocks of the crust. it has squeezed into fissures forming dikes; it has burrowed among the strata as intrusive sheets; it has melted the rocks away or lifted the overlying strata, filling the chambers which it has made with intrusive masses. during all geological ages molten rock has found way to the surface, and volcanoes have darkened the sky with clouds of ashes and poured streams of glowing lava down their sides. the older strata,--the strata which have been most deeply buried,--and especially those which have suffered most from folding and from fracture, show the largest amount of igneous intrusions. the molten rock which has been driven from the earth's interior to within the crust or to the surface during geologic time must be reckoned in millions of cubic miles. [illustration: fig. . , limestone; , tuff; , , , shale with marine shells; , , lava, dotted portions scoriaceous. give the history recorded in this section] [illustration: fig. . _a_, sedimentary strata with intrusive sheets; _b_, sedimentary strata; _c_, lava flow; _d_, dike. give the succession of events recorded in this section] [illustration: fig. . which of the lava sheets of this section are contemporaneous anti which intrusive,--_a_, whose upper surface is overlain with a conglomerate of rolled lava pebbles; _b_, the cracks and seams of whose upper surface are filled with the material of the overlying sandstone; _c_, which breaks across the strata in which it is imbedded; _d_, which includes fragments of both the underlying and overlying strata and penetrates their crevices and seams?] [illustration: fig. . mato tepee, wyoming this magnificent tower of igneous rock three hundred feet in height has been called by some a volcanic neck. is the direction of the columns that which would obtain in the cylindrical pipe of a volcano? the tower is probably the remnant of a small laccolith, an outlying member of a group of laccoliths situated not far distant] the interior condition of the earth and causes of vulcanism and deformation the problems of volcanoes and of deformation are so closely connected with that of the earth's interior that we may consider them together. few of these problems are solved, and we may only state some known facts and the probable conclusions which may be drawn as inferences from them. =the interior of the earth is hot.= volcanoes prove that in many parts of the earth there exist within reach of the surface regions of such intense heat that the rock is in a molten condition. deep wells and mines show everywhere an increase in temperature below the surface shell affected by the heat of summer and the cold of winter,--a shell in temperate latitudes sixty or seventy feet thick. thus in a boring more than a mile deep at schladebach, germany, the earth grows warmer at the rate of ° f. for every sixty-seven feet as we descend. taking the average rate of increase at one degree for every sixty feet of descent, and assuming that this rate, observed at the moderate distances open to observation, continues to at least thirty-five miles, the temperature at that depth must be more than three thousand degrees,--a temperature at which all ordinary rocks would melt at the earth's surface. the rate of increase in temperature probably lessens as we go downward, and it may not be appreciable below a few hundred miles. but there is no reason to doubt that _the interior of the earth is intensely hot_. below a depth of one or two score miles we may imagine the rocks everywhere glowing with heat. although the heat of the interior is great enough to melt all rocks at atmospheric pressure, it does not follow that the interior is fluid. pressure raises the fusing point of rocks, and the weight of the crust may keep the interior in what may be called a solid state, although so hot as to be a liquid or a gas were the pressure to be removed. =the interior of the earth is dense and heavy.= the earth behaves as a globe more rigid than glass under the strains to which it is subjected by the attractions of the sun and moon and other heavenly bodies. the jar of world-shaking earthquakes passes through the earth's interior with nearly twice the velocity with which it would traverse solid steel, and since the speed of elastic waves depends on the density and elasticity of the medium, it follows that the globe is as a whole more dense and rigid than steel. _the interior of the earth is extremely dense and rigid._ the common rocks of the crust are about two and a half times heavier than water, while the earth as a whole weighs five and six-tenths times as much as a globe of water of the same size. _the interior is therefore much more heavy than the crust._ this may be caused in part by compression of the interior under the enormous weight of the crust, and in part also by an assortment of material, the heavier substances, such as the heavy metals, having gravitated towards the center. between the crust, which is solid because it is cool, and the interior, which is hot enough to melt were it not for the pressure which keeps it dense and rigid, there may be an intermediate zone in which heat and pressure are so evenly balanced that here rock liquefies whenever and wherever the pressure upon it may be relieved by movements of the crust. it is perhaps from such a subcrustal layer that the lava of volcanoes is supplied. =the causes of volcanic action.= it is now generally believed that the _heat_ of volcanoes is that of the earth's interior. other causes, such as friction and crushing in the making of mountains and the chemical reactions between oxidizing agents of the crust and the unoxidized interior, have been suggested, but to most geologists they seem inadequate. there is much difference of opinion as to the _force_ which causes molten rock to rise to the surface in the ducts of volcanoes. steam is so evidently concerned in explosive eruptions that many believe that lava is driven upward by the expansive force of the steam with which it is charged, much as a viscid liquid rises and boils over in a test tube or kettle. but in quiet eruptions, and still more in the irruption of intrusive sheets and masses, there is little if any evidence that steam is the driving force. it is therefore believed by many geologists that it is _pressure due to crustal movements and internal stresses_ which squeezes molten rock from below into fissures and ducts in the crust. it is held by some that where considerable water is supplied to the rising column of lava, as from the ground water of the surrounding region, and where the lava is viscid so that steam does not readily escape, the eruption is of the explosive type; when these conditions do not obtain, the lava outwells quietly, as in the hawaiian volcanoes. it is held by others not only that volcanoes are due to the outflow of the earth's deep-seated heat, but also that the steam and other emitted gases are for the most part native to the earth's interior and never have had place in the circulation of atmospheric and ground waters. =volcanic action and deformation.= volcanoes do not occur on wide plains or among ancient mountains. on the other hand, where movements of the earth's crust are in progress in the uplift of high plateaus, and still more in mountain making, molten rock may reach the surface, or may be driven upward toward it forming great intrusive masses. thus extensive lava flows accompanied the upheaval of the block mountains of western north america and the uplift of the colorado plateau. a line of recent volcanoes may be traced along the system of rift valleys which extends from the jordan and dead sea through eastern africa to lake nyassa. the volcanoes of the andes show how conspicuous volcanic action may be in young rising ranges. folded mountains often show a core of igneous rock, which by long erosion has come to form the axis and the highest peaks of the range, as if the molten rock had been squeezed up under the rising upfolds. as we decipher the records of the rocks in historical geology we shall see more fully how, in all the past, volcanic action has characterized the periods of great crustal movements, and how it has been absent when and where the earth's crust has remained comparatively at rest. =the causes of deformation.= as the earth's interior, or nucleus, is highly heated it must be constantly though slowly losing its heat by conduction through the crust and into space; and since the nucleus is cooling it must also be contracting. the nucleus has contracted also because of the extrusion of molten matter, the loss of constituent gases given off in volcanic eruptions, and (still more important) the compression and consolidation of its material under gravity. as the nucleus contracts, it tends to draw away from the cooled and solid crust, and the latter settles, adapting itself to the shrinking nucleus much as the skin of a withering apple wrinkles down upon the shrunken fruit. the unsupported weight of the spherical crust develops enormous tangential pressures, similar to the stresses of an arch or dome, and when these lateral thrusts accumulate beyond the power of resistance the solid rock is warped and folded and broken. since the planet attained its present mass it has thus been lessening in volume. notwithstanding local and relative upheavals the earth's surface on the whole has drawn nearer and nearer to the center. the portions of the lithosphere which have been carried down the farthest have received the waters of the oceans, while those portions which have been carried down the least have emerged as continents. although it serves our convenience to refer the movements of the crust to the sea level as datum plane, it is understood that this level is by no means fixed. changes in the ocean basins increase or reduce their capacity and thus lower or raise the level of the sea. but since these basins are connected, the effect of any change upon the water level is so distributed that it is far less noticeable than a corresponding change would be upon the land. chapter xiii metamorphism and mineral veins under the action of internal agencies rocks of all kinds may be rendered harder, more firmly cemented, and more crystalline. these processes are known as _metamorphism_, and the rocks affected, whether originally sedimentary or igneous, are called _metamorphic rocks_. we may contrast with metamorphism the action of external agencies in weathering, which render rocks less coherent by dissolving their soluble parts and breaking down their crystalline grains. =contact metamorphism.= rocks beneath a lava flow or in contact with igneous intrusions are found to be metamorphosed to various degrees by the heat of the cooling mass. the adjacent strata may be changed only in color, hardness, and texture. thus, next to a dike, bituminous coal may be baked to coke or anthracite, and chalk and limestone to crystalline marble. sandstone may be converted into quartzite, and shale into _argillite_, a compact, massive clay rock. new minerals may also be developed. in sedimentary rocks there may be produced crystals of mica and of _garnet_ (a mineral as hard as quartz, commonly occurring in red, twelve-sided crystals). where the changes are most profound, rocks may be wholly made over in structure and mineral composition. in contact metamorphism, thin sheets of molten rock produce less effect than thicker ones. the strongest heat effects are naturally caused by bosses and regional intrusions, and the zone of change about them may be several miles in width. in these changes heated waters and vapors from the masses of igneous rocks undoubtedly play a very important part. which will be more strongly altered, the rocks about a closed dike in which lava began to cool as soon as it filled the fissure, or the rocks about a dike which opened on the surface and through which the molten rock flowed for some time? taking into consideration the part played by heated waters, which will produce the most far-reaching metamorphism, dikes which cut across the bedding planes or intrusive sheets which are thrust between the strata? =regional metamorphism.= metamorphic rocks occur widespread in many regions, often hundreds of square miles in area, where such extensive changes cannot be accounted for by igneous intrusions. such are the dissected cores of lofty mountains, as the alps, and the worn-down bases of ancient ranges, as in new england, large areas in the piedmont belt, and the laurentian peneplain. in these regions the rocks have yielded to immense pressure. they have been folded, crumpled, and mashed, and even their minute grains, as one may see with a microscope, have often been puckered, broken, and crushed to powder. it is to these mechanical movements and strains which the rocks have suffered in every part that we may attribute their metamorphism, and the degree to which they have been changed is in direct proportion to the degree to which they have been deformed and mashed. other factors, however, have played important parts. rock crushing develops heat, and allows a freer circulation of heated waters and vapors. thus chemical reactions are greatly quickened; minerals are dissolved and redeposited in new positions, or their chemical constituents may recombine in new minerals, entirely changing the nature of the rock, as when, for example, feldspar recrystallizes as quartz and mica. early stages of metamorphism are seen in _slate_. pressure has hardened the marine muds, the arkose (p. ), or the volcanic ash from which slates are derived, and has caused them to cleave by the rearrangement of their particles. under somewhat greater pressure, slate becomes _phyllite_, a clay slate whose cleavage surfaces are lustrous with flat-lying mica flakes. the same pressure which has caused the rock to cleave has set free some of its mineral constituents along the cleavage planes to crystallize there as mica. [illustration: fig. . a foliated rock] =foliation.= under still stronger pressure the whole structure of the rock is altered. the minerals of which it is composed, and the new minerals which develop by heat and pressure, arrange themselves along planes of cleavage or of shear in rudely parallel leaves, or _folia_. of this structure, called _foliation_, we may distinguish two types,--a coarser feldspathic type, and a fine type in which other minerals than feldspar predominate. _gneiss_ is the general name under which are comprised coarsely foliated rocks banded with irregular layers of feldspar and other minerals. the gneisses appear to be due in many cases to the crushing and shearing of deep-seated igneous rocks, such as granite and gabbro. _the crystalline schists_, representing the finer types of foliation, consist of thin, parallel, crystalline leaves, which are often remarkably crumpled. these folia can be distinguished from the laminae of sedimentary rocks by their lenticular form and lack of continuity, and especially by the fact that they consist of platy, crystalline grains, and not of particles rounded by wear. _mica schist_, the most common of schists, and in fact of all metamorphic rocks, is composed of mica and quartz in alternating wavy folia. all gradations between it and phyllite may be traced, and in many cases we may prove it due to the metamorphism of slates and shales. it is widespread in new england and along the eastern side of the appalachians. _talc schist_ consists of quartz and _talc_, a light-colored magnesian mineral of greasy feel, and so soft that it can be scratched with the thumb nail. _hornblende schist_, resulting in many cases from the foliation of basic igneous rocks, is made of folia of hornblende alternating with bands of quartz and feldspar. hornblende schist is common over large areas in the lake superior region. _quartz schist_ is produced from quartzite by the development of fine folia of mica along planes of shear. all gradations may be found between it and unfoliated quartzite on the one hand and mica schist on the other. under the resistless pressure of crustal movements almost any rocks, sandstones, shales, lavas of all kinds, granites, diorites, and gabbros may be metamorphosed into schists by crushing and shearing. limestones, however, are metamorphosed by pressure into _marble_, the grains of carbonate of lime recrystallizing freely to interlocking crystals of calcite. these few examples must suffice of the great class of metamorphic rocks. as we have seen, they owe their origin to the alteration of both of the other classes of rocks--the sedimentary and the igneous--by heat and pressure, assisted usually by the presence of water. the fact of change is seen in their hardness arid cementation, their more or less complete recrystallization, and their foliation; but the change is often so complete that no trace of their original structure and mineral composition remains to tell whether the rocks from which they were derived were sedimentary or igneous, or to what variety of either of these classes they belonged. [illustration: fig. . contorted gneiss, the ottawa river, canada] [illustration: fig. . quartz veins in slate] in many cases, however, the early history of a metamorphic rock can be deciphered. fossils not wholly obliterated may prove it originally water-laid. schists may contain rolled-out pebbles, showing their derivation from a conglomerate. dikes of igneous rocks may be followed into a region where they have been foliated by pressure. the most thoroughly metamorphosed rocks may sometimes be traced out into unaltered sedimentary or igneous rocks, or among them may be found patches of little change where their history maybe read. metamorphism is most common among rocks of the earlier geological ages, and most rare among rocks of recent formation. no doubt it is now in progress where deep-buried sediments are invaded by heat either from intrusive igneous masses or from the earth's interior, or are suffering slow deformation under the thrust of mountain-making forces. suggest how rocks now in process of metamorphism may sometimes be exposed to view. why do metamorphic rocks appear on the surface to-day? mineral veins in regions of folded and broken rocks fissures are frequently found to be filled with sheets of crystalline minerals deposited from solution by underground water, and fissures thus filled are known as _mineral veins_. much of the importance of mineral veins is due to the fact that they are often metalliferous, carrying valuable native metals and metallic ores disseminated in fine particles, in strings, and sometimes in large masses in the midst of the valueless nonmetallic minerals which make up what is known as the _vein stone_. the most common vein stones are _quartz_ and _calcite_. _fluorite_ (calcium fluoride), a mineral harder than calcite and crystallizing in cubes of various colors, and _barite_ (barium sulphate), a heavy white mineral, are abundant in many veins. [illustration: fig. . placer deposits in california _g_, gold-bearing gravels in present river beds; _g´_, ancient gold-bearing river gravels; _a_, _a_, lava flows capping table mountains; _s_, slate. draw a diagram showing by dotted lines conditions before the lava flows occurred. what changes have since taken place?] the gold-bearing quartz veins of california traverse the metamorphic slates of the sierra nevada mountains. below the zone of solution (p. ) these veins consist of a vein stone of quartz mingled with pyrite (p. ), the latter containing threads and grains of native gold. but to the depth of about fifty feet from the surface the pyrite of the vein has been dissolved, leaving a rusty, cellular quartz with grains of the insoluble gold scattered through it. the _placer deposits_ of california and other regions are gold-bearing deposits of gravel and sand in river beds. the heavy gold is apt to be found mostly near or upon the solid rock, and its grains, like those of the sand, are always rounded. how the gold came in the placers we may leave the pupil to suggest. copper is found in a number of ores, and also in the native metal. below the zone of surface changes the ore of a copper vein is often a double sulphide of iron and copper called _chalcopyrite_, a mineral softer than pyrite--it can easily be scratched with a knife--and deeper yellow in color. for several score of feet below the ground the vein may consist of rusty quartz from which the metallic ores have been dissolved; but at the base of the zone of solution we may find exceedingly rich deposits of copper ores,--copper sulphides, red and black copper oxides, and green and blue copper carbonates, which have clearly been brought down in solution from the leached upper portion of the vein. =origin of mineral veins.= both vein stones and ores have been deposited slowly from solution in water, much as crystals of salt are deposited on the sides of a jar of saturated brine. in our study of underground water we learned that it is everywhere circulating through the permeable rocks of the crust, descending to profound depths under the action of gravity and again driven to the surface by hydrostatic pressure. now fissures, wherever they occur, form the trunk channels of the underground circulation. water descends from the surface along these rifts; it moves laterally from either side to the fissure plane, just as ground water seeps through the surrounding rocks from every direction to a well; and it ascends through these natural water ways as in an artesian well, whenever they intersect an aquifer in which water is under hydrostatic pressure. the waters which deposit vein stones and ores are commonly hot, and in many cases they have derived their heat from intrusions of igneous rock still uncooled within the crust. the solvent power of the water is thus greatly increased, and it takes up into solution various substances from the igneous and sedimentary rocks which it traverses. for various reasons these substances stances are deposited in the vein as ores and vein stones. on rising through the fissure the water cools and loses pressure, and its capacity to hold minerals in solution is therefore lessened. besides, as different currents meet in the fissure, some ascending, some descending, and some coming in from the sides, the chemical reaction of these various weak solutions upon one another and upon the walls of the vein precipitates the minerals of vein stuffs and ores. as an illustration of the method of vein deposits we may cite the case of a wooden box pipe used in the comstock mines, nevada, to carry the hot water of the mine from one level to another, which in ten years was lined with calcium carbonate more than half an inch thick. the steamboat springs, nevada, furnish examples of mineral veins in process of formation. the steaming water rises through fissures in volcanic rocks and is now depositing in the rifts a vein stone of quartz, with metallic ores of iron, mercury, lead, and other metals. =reconcentration.= near the base of the zone of solution veins are often stored with exceptionally large and valuable ore deposits. this local enrichment of the vein is due to the reconcentration of its metalliferous ores. as the surface of the land is slowly lowered by weathering and running water, the zone of solution is lowered at an equal rate and encroaches constantly on the zone of cementation. the minerals of veins are therefore constantly being dissolved along their upper portions and carried down the fissures by ground water to lower levels, where they are redeposited. many of the richest ore deposits are thus due to successive concentrations: the ores were leached originally from the rocks to a large extent by laterally seeping waters; they were concentrated in the ore deposits of the vein chiefly by ascending currents; they have been reconcentrated by descending waters in the way just mentioned. =the original source of the metals.= it is to the igneous rocks that we may look for the original source of the metals of veins. lavas contain minute percentages of various metallic compounds, and no doubt this was the case also with the igneous rocks which formed the original earth crust. by the erosion of the igneous rocks the metals have been distributed among sedimentary strata, and even the sea has taken into solution an appreciable amount of gold and other metals, but in this widely diffused condition they are wholly useless to man. the concentration which has made them available is due to the interaction of many agencies. earth movements fracturing deeply the rocks of the crust, the intrusion of heated masses, the circulation of underground waters, have all coöperated in the concentration of the metals of mineral veins. while fissure veins are the most important of mineral veins, the latter term is applied also to any water way which has been filled by similar deposits from solution. thus in soluble rocks, such as limestones, joints enlarged by percolating water are sometimes filled with metalliferous deposits, as, for example, the lead and zinc deposits of the upper mississippi valley. even a porous aquifer may be made the seat of mineral deposits, as in the case of some copper-bearing and silver-bearing sandstones of new mexico. * * * * * [illustration: fig. . geological map of the united states and part of canada] * * * * * part iii historical geology chapter xiv the geological record =what a formation records.= we have already learned that each individual body of stratified rock, or formation, constitutes a record of the time when it was laid. the structure and the character of the sediments of each formation tell whether the area was land or sea at the time when they were spread; and if the former, whether the land was river plain, or lake bed, or was covered with wind-blown sands, or by the deposits of an ice sheet. if the sediments are marine, we may know also whether they were laid in shoal water near the shore or in deeper water out at sea, and whether during a period of emergence, or during a period of subsidence when the sea transgressed the land. by the same means each formation records the stage in the cycle of erosion of the land mass from which its sediments were derived (p. ). an unconformity between two marine formations records the fact that between the periods when they were deposited in the sea the area emerged as land and suffered erosion (p. ). the attitude and structure of the strata tell also of the foldings and fractures, the deformation and the metamorphism, which they have suffered; and the igneous rocks associated with them as lava flows and igneous intrusions add other details to the story. each formation is thus a separate local chapter in the geological history of the earth, and its strata are its leaves. it contains an authentic record of the physical conditions--the geography--of the time and place when and where its sediments were laid. =past cycles of erosion.= these chapters in the history of the planet are very numerous, although much of the record has been destroyed in various ways. a succession of different formations is usually seen in any considerable section of the crust, such as a deep canyon or where the edges of upturned strata are exposed to view on the flanks of mountain ranges; and in any extensive area, such as a state of the union or a province of canada, the number of formations outcropping on the surface is large. it is thus learned that our present continent is made up for the most part of old continental deltas. some, recently emerged as the strata of young coastal plains, are the records of recent cycles of erosion; while others were deposited in the early history of the earth, and in many instances have been crumpled into mountains, which afterwards were leveled to their bases and lowered beneath the sea to receive a cover of later sediments before they were again uplifted to form land. the cycle of erosion now in progress and recorded in the layers of stratified rock being spread beneath the sea in continental deltas has therefore been preceded by many similar cycles. again and again movements of the crust have brought to an end one cycle--sometimes when only well under way, and sometimes when drawing toward its close--and have begun another. again and again they have added to the land areas which before were sea, with all their deposition records of earlier cycles, or have lowered areas of land beneath the sea to receive new sediments. =the age of the earth.= the thickness of the stratified rocks now exposed upon the eroded surface of the continents is very great. in the appalachian region the strata are seven or eight miles thick, and still greater thicknesses have been measured in several other mountain ranges. the aggregate thickness of all the formations of the stratified rocks of the earth's crust, giving to each formation its maximum thickness wherever found, amounts to not less than forty miles. knowing how slowly sediments accumulate upon the sea floor (p. ), we must believe that the successive cycles which the earth has seen stretch back into a past almost inconceivably remote, and measure tens of millions and perhaps even hundreds of millions of years. =how the formations are correlated and the geological record made up.= arranged in the order of their succession, the formations of the earth's crust would constitute a connected record in which the geological history of the planet may be read, and therefore known as the _geological record_. but to arrange the formations in their natural order is not an easy task. a complete set of the volumes of the record is to be found in no single region. their leaves and chapters are scattered over the land surface of the globe. in one area certain chapters may be found, though perhaps with many missing leaves, and with intervening chapters wanting, and these absent parts perhaps can be supplied only after long search through many other regions. adjacent strata in any region are arranged according to the _law of superposition_, i.e. any stratum is younger than that on which it was deposited, just as in a pile of paper, any sheet was laid later than that on which it rests. where rocks have been disturbed, their original attitude must be determined before the law can be applied. nor can the law of superposition be used in identifying and comparing the strata of different regions where the formations cannot be traced continuously from one region to the other. the formations of different regions are arranged in their true order by the _law of included organisms_; i.e. formations, however widely separated, which contain a similar assemblage of fossils are equivalent and belong to the same division of geological time. the correlation of formations by means of fossils may be explained by the formations now being deposited about the north atlantic. lithologically they are extremely various. on the continental shelf of north america limestones of different kinds are forming off florida, and sandstones and shales from georgia northward. separated from them by the deep atlantic oozes are other sedimentary deposits now accumulating along the west coast of europe. if now all these offshore formations were raised to open air, how could they be correlated? surely not by lithological likeness, for in this respect they would be quite diverse. all would be similar, however, in the fossils which they contain. some fossil species would be identical in all these formations and others would be closely allied. making all due allowance for differences in species due to local differences in climate and other physical causes, it would still be plain that plants and animals so similar lived at the same period of time, and that the formations in which their remains were imbedded were contemporaneous in a broad way. the presence of the bones of whales and other marine mammals would prove that the strata were laid after the appearance of mammals upon earth, and imbedded relics of man would give a still closer approximation to their age. in the same way we correlate the earlier geological formations. for example, in there were collected the first fossils ever found on the antarctic continent. among the dozen specimens obtained were some fossil ammonites (a family of chambered shells) of genera which are found on other continents in certain formations classified as the cretaceous system, and which occur neither above these formations nor below them. on the basis of these few fossils we may be confident that the strata in which they were found in the antarctic region were laid in the same period of geologic time as were the cretaceous rocks of the united states and canada. =the record as a time scale.= by means of the law of included organisms and the law of superposition the formations of different countries and continents are correlated and arranged in their natural order. when the geological record is thus obtained it may be used as a universal time scale for geological history. geological time is separated into divisions corresponding to the times during which the successive formations were laid. the largest assemblages of formations are known as groups, while the corresponding divisions of time are known as eras. groups are subdivided into systems, and systems into series. series are divided into stages and substages,--subdivisions which do not concern us in this brief treatise. the corresponding divisions of time are given in the following table. _strata_ _time_ group era system period series epoch the geologist is now prepared to read the physical history--the geographical development--of any country or of any continent by means of its formations, when he has given each formation its true place in the geological record as a time scale. the following chart exhibits the main divisions of the record, the name given to each being given also to the corresponding time division. thus we speak of the _cambrian system_, meaning a certain succession of formations which are classified together because of broad resemblances in their included organisms; and of the _cambrian period_, meaning the time during which these rocks were deposited. _group and era_ _system and period_ _series and epoch_ { recent { quaternary . . . . { pleistocene { cenozoic . . . . { { pliocene { tertiary . . . . { miocene { eocene { cretaceous mesozoic . . . . { jurassic { triassic { permian { carboniferous . . { pennsylvanian { { mississippian paleozoic . . . . { devonian { silurian { ordovician { cambrian algonkian archean fossils and what they teach the geological formations contain a record still more important than that of the geographical development of the continents; the fossils imbedded in the rocks of each formation tell of the kinds of animals and plants which inhabited the earth at that time, and from these fossils we are therefore able to construct the history of life upon the earth. =fossils.= these remains of organisms are found in the strata in all degrees of perfection, from trails and tracks and fragmentary impressions, to perfectly preserved shells, wood, bones, and complete skeletons. as a rule, it is only the hard parts of animals and plants which have left any traces in the rocks. sometimes the original hard substance is preserved, but more often it has been replaced by some less soluble material. petrifaction, as this process of slow replacement is called, is often carried on in the most exquisite detail. when wood, for example, is undergoing petrifaction, the woody tissue may be replaced, particle by particle, by silica in solution through the action of underground waters, even the microscopic structures of the wood being perfectly reproduced. in shells originally made of _aragonite_, a crystalline form of carbonate of lime, that mineral is usually replaced by _calcite_, a more stable form of the same substance. the most common petrifying materials are calcite, silica, and pyrite. often the organic substance has neither been preserved nor replaced, but the _form_ has been retained by means of molds and casts. permanent impressions, or molds, may be made in sediments not only by the hard parts of organisms, but also by such soft and perishable parts as the leaves of plants, and, in the rarest instances, by the skin of animals and the feathers of birds. in fine-grained limestones even the imprints of jellyfish have been retained. the different kinds of molds and casts may be illustrated by means of a clam shell and some moist clay, the latter representing the sediments in which the remains of animals and plants are entombed. imbedding the shell in the clay and allowing the clay to harden, we have a _mold of the exterior_ of the shell, as is seen on cutting the clay matrix in two and removing the shell from it. filling this mold with clay of different color, we obtain a _cast of the exterior_, which represents accurately the original form and surface markings of the shell. in nature, shells and other relics of animals or plants are often removed by being dissolved by percolating waters, and the molds are either filled with sediments or with minerals deposited from solution. where the fossil is hollow, a _cast of the interior_ is made in the same way. interior casts of shells reproduce any markings on the inside of the valves, and casts of the interior of the skulls of ancient vertebrates show the form and size of their brains. =imperfection of the life record.= at the present time only the smallest fraction of the life on earth ever gets entombed in rocks now forming. in the forest great fallen tree trunks, as well as dead leaves, decay, and only add a little to the layer of dark vegetable mold from which they grew. the bones of land animals are, for the most part, left unburied on the surface and are soon destroyed by chemical agencies. even where, as in the swamps of river, flood plains and in other bogs, there are preserved the remains of plants, and sometimes insects, together with the bones of some animal drowned or mired, in most cases these swamp and bog deposits are sooner or later destroyed by the shifting channels of the stream or by the general erosion of the land. in the sea the conditions for preservation are more favorable than on land; yet even here the proportion of animals and plants whose hard parts are fossilized is very small compared with those which either totally decay before they are buried in slowly accumulating sediments or are ground to powder by waves and currents. we may infer that during each period of the past, as at the present, only a very insignificant fraction of the innumerable organisms of sea and land escaped destruction and left in continental and oceanic deposits permanent records of their existence. scanty as these original life records must have been, they have been largely destroyed by metamorphism of the rocks in which they were imbedded, by solution in underground waters, and by the vast denudation under which the sediments of earlier periods have been eroded to furnish materials for the sedimentary records of later times. moreover, very much of what has escaped destruction still remains undiscovered. the immense bulk of the stratified rocks is buried and inaccessible, and the records of the past which it contains can never be known. comparatively few outcrops have been thoroughly searched for fossils. although new species are constantly being discovered, each discovery may be considered as the outcome of a series of happy accidents,--that the remains of individuals of this particular species happened to be imbedded and fossilized, that they happened to escape destruction during long ages, and that they happened to be exposed and found. =some inferences from the records of the history of life upon the planet.= meager as are these records, they set forth plainly some important truths which we will now briefly mention. . each series of the stratified rocks, except the very deepest, contains vestiges of life. hence _the earth was tenanted by living creatures for an uncalculated length of time before human history began_. . _life on the earth has been ever-changing._ the youngest strata hold the remains of existing species of animals and plants and those of species and varieties closely allied to them. strata somewhat older contain fewer existing species, and in strata of a still earlier, but by no means an ancient epoch, no existing species are to be found; the species of that epoch and of previous epochs have vanished from the living world. during all geological time since life began on earth old species have constantly become extinct and with them the genera and families to which they belong, and other species, genera, and families have replaced them. the fossils of each formation differ on the whole from those of every other. the assemblage of animals and plants (the _fauna-flora_) of each epoch differs from that of every other epoch. in many cases the extinction of a type has been gradual; in other instances apparently abrupt. there is no evidence that any organism once become extinct has ever reappeared. the duration of a species in time, or its "vertical range" through the strata, varies greatly. some species are limited to a stratum a few feet in thickness; some may range through an entire formation and be found but little modified in still higher beds. a formation may thus often be divided into zones, each characterized by its own peculiar species. as a rule, the simpler organisms have a longer duration as species, though not as individuals, than the more complex. . _the larger zoölogical and botanical groupings survive longer than the smaller._ species are so short-lived that a single geological epoch may be marked by several more or less complete extinctions of the species of its fauna-flora and their replacement by other species. a genus continues with new species after all the species with which it began have become extinct. families survive genera, and orders families. classes are so long-lived that most of those which are known from the earliest formations are represented by living forms, and no subkingdom has ever become extinct. thus, to take an example from the stony corals,--the _zoantharia_,--the particular characters--which constituted a certain _species_--_facosites niagarensis_--of the order are confined to the niagara series. its _generic_ characters appeared in other species earlier in the silurian and continued through the devonian. its _family_ characters, represented in different genera and species, range from the ordovician to the close of the paleozoic; while the characters which it shares with all its order, the zoantharia, began in the cambrian and are found in living species. . _the change in organisms has been gradual._ the fossils of each life zone and of each formation of a conformable series closely resemble, with some explainable exceptions, those of the beds immediately above and below. the animals and plants which tenanted the earth during any geological epoch are so closely related to those of the preceding and the succeeding epochs that we may consider them to be the descendants of the one and the ancestors of the other, thus accounting for the resemblance by heredity. it is therefore believed that the species of animals and plants now living on the earth are the descendants of the species whose remains we find entombed in the rocks, and that the chain of life has been unbroken since its beginning. . _the change in species has been a gradual differentiation._ tracing the lines of descent of various animals and plants of the present backward through the divisions of geologic time, we find that these lines of descent converge and unite in simpler and still simpler types. the development of life may be represented by a tree whose trunk is found in the earliest ages and whose branches spread and subdivide to the growing twigs of present species. . _the change in organisms throughout geologic time has been a progressive change._ in the earliest ages the only animals and plants on the earth were lowly forms, simple and generalized in structure; while succeeding ages have been characterized by the introduction of types more and more specialized and complex, and therefore of higher rank in the scale of being. thus the algonkian contains the remains of only the humblest forms of the invertebrates. in the cambrian, ordovician, and silurian the invertebrates were represented in all their subkingdoms by a varied fauna. in the devonian, fishes--the lowest of the vertebrates--became abundant. amphibians made their entry on the stage in the carboniferous, and reptiles came to rule the world in the mesozoic. mammals culminated in the tertiary in strange forms which became more and more like those of the present as the long ages of that era rolled on; and latest of all appeared the noblest product of the creative process, man. just as growth is characteristic of the individual life, so gradual, progressive change, or evolution, has characterized the history of life upon the planet. the evolution of the organic kingdom from its primitive germinal forms to the complex and highly organized fauna-flora of to-day may be compared to the growth of some noble oak as it rises from the acorn, spreading loftier and more widely extended branches as it grows. . while higher and still higher types have continually been evolved, until man, the highest of all, appeared, _the lower and earlier types have generally persisted_. some which reached their culmination early in the history of the earth have since changed only in slight adjustments to a changing environment. thus the brachiopods, a type of shellfish, have made no progress since the paleozoic, and some of their earliest known genera are represented by living forms hardly to be distinguished from their ancient ancestors. the lowest and earliest branches of the tree of life have risen to no higher levels since they reached their climax of development long ago. . a strange parallel has been found to exist between the evolution of organisms and the development of the individual. in the embryonic stages of its growth the individual passes swiftly through the successive stages through which its ancestors evolved during the millions of years of geologic time. _the development of the individual recapitulates the evolution of the race._ * * * * * the frog is a typical amphibian. as a tadpole it passes through a stage identical in several well-known features with the maturity of fishes; as, for example, its aquatic life, the tail by which it swims, and the gills through which it breathes. it is a fair inference that the tadpole stage in the life history of the frog represents a stage in the evolution of its kind,--that the amphibia are derived from fishlike ancestral forms. this inference is amply confirmed in the geological record; fishes appeared before amphibia and were connected with them by transitional forms. =the great length of geologic time inferred from the slow change of species.= life forms, like land forms, are thus subject to change under the influence of their changing environment and of forces acting from within. how slowly they change may be seen in the apparent stability of existing species. in the lifetime of the observer and even in the recorded history of man, species seem as stable as the mountain and the river. but life forms and land forms are alike variable, both in nature and still more under the shaping hand of man. as man has modified the face of the earth with his great engineering works, so he has produced widely different varieties of many kinds of domesticated plants and animals, such as the varieties of the dog and the horse, the apple and the rose, which may be regarded in some respects as new species in the making. we have assumed that land forms have changed in the past under the influence of forces now in operation. assuming also that life forms have always changed as they are changing at present, we come to realize something of the immensity of geologic time required for the evolution of life from its earliest lowly forms up to man. it is because the onward march of life has taken the same general course the world over that we are able to use it as a _universal time scale_ and divide geologic time into ages and minor subdivisions according to the ruling or characteristic organisms then living on the earth. thus, since vertebrates appeared, we have in succession the age of fishes, the age of amphibians, the age of reptiles, and the age of mammals. the chart given on page is thus based on the law of superposition and the law of the evolution of organisms. the first law gives the succession of the formations in local areas. the fossils which they contain demonstrate the law of the progressive appearance of organisms, and by means of this law the formations of different countries are correlated and set each in its place in a universal time scale and grouped together according to the affinities of their imbedded organic remains. =geologic time divisions compared with those of human history.= we may compare the division of geologic time into eras, periods, and other divisions according to the dominant life of the time, to the ill-defined ages into which human history is divided according to the dominance of some nation, ruler, or other characteristic feature. thus we speak of the _dark ages_, the _age of elizabeth_, and the _age of electricity_. these crude divisions would be of much value if, as in the case of geologic time, we had no exact reckoning of human history by years. and as the course of human history has flowed in an unbroken stream along quiet reaches of slow change and through periods of rapid change and revolution, so with the course of geologic history. periods of quiescence, in which revolutionary forces are perhaps gathering head, alternate with periods of comparatively rapid change in physical geography and in organisms, when new and higher forms appear which serve to draw the boundary line of new epochs. nevertheless, geological history is a continuous progress; its periods and epochs shade into one another by imperceptible gradations, and all our subdivisions must needs be vague and more or less arbitrary. =how fossils tell of the geography of the past.= fossils are used not only as a record of the development of life upon the earth, but also in testimony to the physical geography of past epochs. they indicate whether in any region the climate was tropical, temperate, or arctic. since species spread slowly from some center of dispersion where they originate until some barrier limits their migration farther, the occurrence of the same species in rocks of the same system in different countries implies the absence of such barriers at the period. thus in the collection of antarctic fossils referred to on page there were shallow-water marine shells identical in species with mesozoic shells found in india and in the southern extremity of south america. since such organisms are not distributed by the currents of the deep sea and cannot migrate along its bottom, we infer a shallow-water connection in mesozoic times between india, south america, and the antarctic region. such a shallow-water connection would be offered along the marginal shelf of a continent uniting these now widely separated countries. chapter xv the pre-cambrian systems =the earth's beginnings.= the geological record does not tell us of the beginnings of the earth. the history of the planet, as we have every reason to believe, stretches far back beyond the period of the oldest stratified rocks, and is involved in the history of the solar system and of the nebula,--the cloud of glowing gases or of cosmic dust,--from which the sun and planets are believed to have been derived. =the nebular hypothesis.= it was long held that the earth began as a vaporous, shining sphere, formed by the gathering together of the material of a gaseous ring which had been detached from a cooling and shrinking nebula. such a vaporous sphere would condense to a liquid fiery globe, whose surface would become cold and solid, while the interior would long remain intensely hot because of the slow conductivity of the crust. under these conditions the primeval atmosphere of the earth must have contained in vapor the water now belonging to the earth's crust and surface. it also held all the oxygen since locked up in rocks by their oxidation, and all the carbon dioxide which has since been laid away in limestones, besides that corresponding to the carbon of carbonaceous deposits, such as peat, coal, and petroleum. on this hypothesis the original atmosphere was dense, dark, and noxious, and enormously heavier than the atmosphere at present. =the accretion hypothesis.= on the other hand, it has been recently suggested that the earth may have grown to its present size by the gradual accretion of meteoritic masses. such cold, stony bodies might have come together at so slow a rate that the heat caused by their impact would not raise sensibly the temperature of the growing planet. thus the surface of the earth may never have been hot and luminous; but as the loose aggregation of stony masses grew larger and was more and more compressed by its own gravitation, the heat thus generated raised the interior to high temperatures, while from time to time molten rock was intruded among the loose, cold meteoritic masses of the crust and outpoured upon the surface. such a spiral nebula might be formed by the close approach of one star to another,--of a passing star to our own sun, for example, before the birth of the solar system. as the pull of the moon raises the tides on opposite sides of the earth, so, it is supposed, the pull of the passing star released the explosive forces of the sun, and two streams of matter were flung out from it. the knots in the arms formed the nuclei of the planets. the gaseous matter scattered outside the knots cooled into small stony masses, revolving about a central mass and hence called planetesimals (little planets). like the meteorites which still fall upon the earth, the planetesimals were gradually gathered in by the nuclear knots, which thus grew to the present planets. it is supposed that the meteorites of which the earth was built brought to it, as meteorites do now, various gases shut up within their pores. as the heat of the interior increased, these gases transpired to the surface and formed the primitive atmosphere and hydrosphere. the atmosphere has therefore grown slowly from the smallest beginnings. gases emitted from the interior in volcanic eruptions and in other ways have ever added to it, and are adding to it now. on the other hand, the atmosphere has constantly suffered loss, as it has been robbed of oxygen by the oxidation of rocks in weathering, and of carbon dioxide in the making of limestones and carbonaceous deposits. while all hypotheses of the earth's beginnings are as yet unproved speculations, they serve to bring to mind one of the chief lessons which geology has to teach,--that the duration of the earth in time, like the extension of the universe in space, is vastly beyond the power of the human mind to realize. behind the history recorded in the rocks, which stretches back for many million years, lies the long unrecorded history of the beginnings of the planet; and still farther in the abysses of the past are dimly seen the cycles of the evolution of the solar system and of the nebula which gave it birth. we pass now from the dim realm of speculation to the earliest era of the recorded history of the earth, where some certain facts may be observed and some sure inferences from them may be drawn. the archean the oldest known sedimentary strata, wherever they are exposed by uplift and erosion, are found to be involved with a mass of crystalline rocks which possesses the same characteristics in all parts of the world. it consists of foliated rocks, gneisses, and schists of various kinds, which have been cut with dikes and other intrusions of molten rock, and have been broken, crumpled, and crushed, and left in interlocking masses so confused that their true arrangement can usually be made out only with the greatest difficulty if at all. the condition of this body of crystalline rocks is due to the fact that they have suffered not only from the faultings, foldings, and igneous intrusions of their time, but necessarily, also, from those of all later geological ages. at present three leading theories are held as to the origin of these basal crystalline rocks. . they are considered by perhaps the majority of the geologists who have studied them most carefully to be igneous rocks intruded in a molten state among the sedimentary rocks involved with them. in many localities this relation is proved by the phenomena of contact (p. ); but for the most part the deformations which the rocks have since suffered again and again have been sufficient to destroy such evidence if it ever existed. . an older view regards them as profoundly altered sedimentary strata, the most ancient of the earth. . according to a third theory they represent portions of the earth's original crust; not, indeed, its original surface, but deeper portions uncovered by erosion and afterwards mantled with sedimentary deposits. all these theories agree that the present foliated condition of these rocks is due to the intense metamorphism which they have suffered. it is to this body of crystalline rocks and the stratified rocks involved with it, which form a very small proportion of its mass, that the term _archean_ (greek, arche, beginning) is applied by many geologists. the algonkian in some regions there rests unconformably on the archean an immense body of stratified rocks, thousands and in places even scores of thousands of feet thick, known as the _algonkian_. great unconformities divide it into well-defined systems, but as only the scantiest traces of fossils appear here and there among its strata, it is as yet impossible to correlate the formations of different regions and to give them names of more than local application. we will describe the algonkian rocks of two typical areas. =the grand canyon of the colorado.= we have already studied a very ancient peneplain whose edge is exposed to view deep on the walls of the colorado canyon (_nu´_, fig. ). the formation of flat-lying sandstone which covers this buried land surface is proved by its fossils to belong to the cambrian,--the earliest period of the paleozoic era. the tilted rocks (_b_, fig. ). on whose upturned edges the cambrian sandstone rests are far older, for the physical break which separates them from it records a time interval during which they were upheaved to mountainous ridges and worn down to a low plain. they are therefore classified as algonkian. they comprise two immense series. the upper is more than five thousand feet thick and consists of shales and sandstones with some limestones. separated from it by an unconformity which does not appear in figure , the lower division, seven thousand feet thick, consists chiefly of massive reddish sandstones with seven or more sheets of lava interbedded. the lowest member is a basal conglomerate composed of pebbles derived from the erosion of the dark crumpled schists beneath,--schists which are supposed to be archean. as shown in figure , a strong unconformity (_nm´_, fig. ) parts the schists and the algonkian. the floor on which the algonkian rests is remarkably even, and here again is proved an interval of incalculable length, during which an ancient land mass of archean rocks was baseleveled before it received the cover of the sediments of the later age. =the lake superior region.= in eastern canada an area of pre-cambrian rocks, archean and algonkian, estimated at two million square miles, stretches from the great lakes and the st. lawrence river northward to the confines of the continent, inclosing hudson bay in the arms of a gigantic u. this immense area, which we have already studied as the laurentian peneplain (p. ), extends southward across the canadian border into northern minnesota, wisconsin, and michigan. the rocks of this area are known to be pre-cambrian; for the cambrian strata, wherever found, lie unconformably upon them. [illustration: fig. . ideal section in the lake superior region] the general relations of the formations of that portion of the area which lies about lake superior are shown in figure . great unconformities, _uu´_ separate the algonkian both from the archean and from the cambrian, and divide it into three distinct systems,--the _lower huronian_, the _upper huronian_, and the _keweenawan_. the lower and the upper huronian consist in the main of old sea muds and sands and limy oozes now changed to gneisses, schists, marbles, quartzites, slates, and other metamorphic rocks. the keweenawan is composed of immense piles of lava, such as those of iceland, overlain by bedded sandstones. what remains of these rock systems after the denudation of all later geologic ages is enormous. the lower huronian is more than a mile thick, the upper huronian more than two miles thick, while the keweenawan exceeds nine miles in thickness. the vast length of algonkian time is shown by the thickness of its marine deposits and by the cycles of erosion which it includes. in figure the student may read an outline of the history of the lake superior region, the deformations which it suffered, their relative severity, the times when they occurred, and the erosion cycles marked by the successive unconformities. =other pre-cambrian areas in north america.= pre-cambrian rocks are exposed in various parts of the continent, usually by the erosion of mountain ranges in which their strata were infolded. large areas occur in the maritime provinces of canada. the core of the green mountains of vermont is pre-cambrian, and rocks of these systems occur in scattered patches in western massachusetts. here belong also the oldest rocks of the highlands of the hudson and of new jersey. the adirondack region, an outlier of the laurentian region, exposes pre-cambrian rocks, which have been metamorphosed and tilted by the intrusion of a great boss of igneous rock out of which the central peaks are carved. the core of the blue ridge and probably much of the piedmont belt are of this age. in the black hills the irruption of an immense mass of granite has caused or accompanied the upheaval of pre-cambrian strata and metamorphosed them by heat and pressure into gneisses, schists, quartzites, and slates. in most of these mountainous regions the lowest strata are profoundly changed by metamorphism, and they can be assigned to the pre-cambrian only where they are clearly overlain unconformably by formations proved to be cambrian by their fossils. in the belt mountains of montana, however, the cambrian is underlain by algonkian sediments twelve thousand feet thick, and but little altered. =mineral wealth of the pre-cambrian rocks.= the pre-cambrian rocks are of very great economic importance, because of their extensive metamorphism and the enormous masses of igneous rock which they involve. in many parts of the country they are the source of supply of granite, gneiss, marble, slate, and other such building materials. still more valuable are the stores of iron and copper and other metals which they contain. at the present time the pre-cambrian region about lake superior leads the world in the production of iron ore, its output for being more than five sevenths of the entire output of the whole united states, and exceeding that of any foreign country. the ore bodies consist chiefly of the red oxide of iron (hematite) and occur in troughs of the strata, underlain by some impervious rock. a theory held by many refers the ultimate source of the iron to the igneous rocks of the archean. when these rocks were upheaved and subjected to weathering, their iron compounds were decomposed. their iron was leached out and carried away to be laid in the algonkian water bodies in beds of iron carbonate and other iron compounds. during the later ages, after the algonkian strata had been uplifted to form part of the continent, a second concentration has taken place. descending underground waters charged with oxygen have decomposed the iron carbonate and deposited the iron, in the form of iron oxide, in troughs of the strata where their downward progress was arrested by impervious floors. the pre-cambrian rocks of the eastern united states also are rich in iron. in certain districts, as in the highlands of new jersey, the black oxide of iron (magnetite) is so abundant in beds and disseminated grains that the ordinary surveyor's compass is useless. the pre-cambrian copper mines of the lake superior region are among the richest on the globe. in the igneous rocks copper, next to iron, is the most common of all the useful metals, and it was especially abundant in the keweenawan lavas. after the keweenawan was uplifted to form land, percolating waters leached out much of the copper diffused in the lava sheets and deposited it within steam blebs as amygdules of native copper, in cracks and fissures, and especially as a cement, or matrix, in the interbedded gravels which formed the chief aquifers of the region. the famous calumet and hecla mine follows down the dip of the strata to the depth of nearly a mile and works such an ancient conglomerate whose matrix is pure copper. [illustration: fig. . successive stages in the development of the ovum to the gastrula stage] =the appearance of life.= sometime during the dim ages preceding the cambrian, whether in the archean or in the algonkian we know not, occurred one of the most important events in the history of the earth. life appeared for the first time upon the planet. geology has no evidence whatever to offer as to whence or how life came. all analogies lead us to believe that its appearance must have been sudden. its earliest forms are unknown, but analogy suggests that as every living creature has developed from a single cell, so the earliest organisms upon the globe--the germs from which all later life is supposed to have been evolved--were tiny, unicellular masses of protoplasm, resembling the amoeba of to-day in the simplicity of their structure. such lowly forms were destitute of any hard parts and could leave no evidence of their existence in the record of the rocks. and of their supposed descendants we find so few traces in the pre-cambrian strata that the first steps in organic evolution must be supplied from such analogies in embryology as the following. the fertilized ovum, the cell with which each animal begins its life, grows and multiplies by cell division, and develops into a hollow globe of cells called the _blastosphere_. this stage is succeeded by the stage of the _gastrula_,--an ovoid or cup-shaped body with a double wall of cells inclosing a body cavity, and with an opening, the primitive mouth. each of these early embryological stages is represented by living animals,--the undivided cell by the _protozoa_, the blastosphere by some rare forms, and the gastrula in the essential structure of the _coelenterates_,--the subkingdom to which the fresh-water hydra and the corals belong. all forms of animal life, from the coelenterates to the mammals, follow the same path in their embryological development as far as the gastrula stage, but here their paths widely diverge, those of each subkingdom going their own separate ways. we may infer, therefore, that during the pre-cambrian periods organic evolution followed the lines thus dimly traced. the earliest one-celled protozoa were probably succeeded by many-celled animals of the type of the blastosphere, and these by gastrula-like organisms. from the gastrula type the higher subdivisions of animal life probably diverged, as separate branches from a common trunk. much or all of this vast differentiation was accomplished before the opening of the next era; for all the subkingdoms are represented in the cambrian except the vertebrates. =evidences of pre-cambrian life.= an indirect evidence of life during the pre-cambrian periods is found in the abundant and varied fauna of the next period; for, if the theory of evolution is correct, the differentiation of the cambrian fauna was a long process which might well have required for its accomplishment a large part of pre-cambrian time. other indirect evidences are the pre-cambrian limestones, iron ores, and graphite deposits, since such minerals and rocks have been formed in later times by the help of organisms. if the carbonate of lime of the algonkian limestones and marbles was extracted from sea water by organisms, as is done at present by corals, mollusks, and other humble animals and plants, the life of those ancient seas must have been abundant. graphite, a soft black mineral composed of carbon and used in the manufacture of lead pencils and as a lubricant, occurs widely in the metamorphic pre-cambrian rocks. it is known to be produced in some cases by the metamorphism of coal, which itself is formed of decomposed vegetal tissues. seams of graphite may therefore represent accumulations of vegetal matter such as seaweed. but limestone, iron ores, and graphite can be produced by chemical processes, and their presence in the pre-cambrian makes it only probable, and not certain, that life existed at that time. =pre-cambrian fossils.= very rarely has any clear trace of an organism been found in the most ancient chapters of the geological record, so many of their leaves have been destroyed and so far have their pages been defaced. omitting structures whose organic nature has been questioned, there are left to mention a tiny seashell of one of the most lowly types,--a _discina_ from the pre-cambrian rocks of the colorado canyon,--and from the pre-cambrian rocks of montana trails of annelid worms and casts of their burrows in ancient beaches, and fragments of the tests of crustaceans. these diverse forms indicate that before the algonkian had closed, life was abundant and had widely differentiated. we may expect that other forms will be discovered as the rocks are closely searched. =pre-cambrian geography.= our knowledge is far too meager to warrant an attempt to draw the varying outlines of sea and land during the archean and algonkian eras. pre-cambrian time probably was longer than all later geological time down to the present, as we may infer from the vast thicknesses of its rocks and the unconformities which part them. we know that during its long periods land masses again and again rose from the sea, were worn low, and were submerged and covered with the waste of other lands. but the formations of separated regions cannot be correlated because of the absence of fossils, and nothing more can be made out than the detached chapters of local histories, such as the outline given of the district about lake superior. the pre-cambrian rocks show no evidence of any forces then at work upon the earth except the forces which are at work upon it now. the most ancient sediments known are so like the sediments now being laid that we may infer that they were formed under conditions essentially similar to those of the present time. there is no proof that the sands of the pre-cambrian sandstones were swept by any more powerful waves and currents than are offshore sands to-day, or that the muds of the pre-cambrian shales settled to the sea floor in less quiet water than such muds settle in at present. the pre-cambrian lands were, no doubt, worn by wind and weather, beaten by rain, and furrowed by streams as now, and, as now, they fronted the ocean with beaches on which waves dashed and along which tidal currents ran. perhaps the chief difference between the pre-cambrian and the present was the absence of life upon the land. so far as we have any knowledge, no forests covered the mountain sides, no verdure carpeted the plains, and no animals lived on the ground or in the air. it is permitted to think of the most ancient lands as deserts of barren rock and rock waste swept by rains and trenched by powerful streams. we may therefore suppose that the processes of their destruction went on more rapidly than at present. chapter xvi the cambrian =the paleozoic era.= the second volume of the geological record, called the paleozoic (greek, _palaios_, ancient; _zoe_, life), has come down to us far less mutilated and defaced than has the first volume, which contains the traces of the most ancient life of the globe. fossils are far more abundant in the paleozoic than in the earlier strata, while the sediments in which they were entombed have suffered far less from metamorphism and other causes, and have been less widely buried from view, than the strata of the pre-cambrian groups. by means of their fossils we can correlate the formations of widely separated regions from the beginning of the paleozoic on, and can therefore trace some outline of the history of the continents. paleozoic time, although shorter than the pre-cambrian as measured by the thickness of the strata, must still be reckoned in millions of years. during this vast reach of time the changes in organisms were very great. it is according to the successive stages in the advance of life that the paleozoic formations are arranged in five systems,--the _cambrian_, the _ordovician_, the _silurian_, the _devonian_, and the _carboniferous_. on the same basis the first three systems are grouped together as the older paleozoic, because they alike are characterized by the dominance of the invertebrates; while the last two systems are united in the later paleozoic, and are characterized, the one by the dominance of fishes, and the other by the appearance of amphibians and reptiles. each of these systems is world-wide in its distribution, and may be recognized on any continent by its own peculiar fauna. the names first given them in great britain have therefore come into general use, while their subdivisions, which often cannot be correlated in different countries and different regions, are usually given local names. the first three systems were named from the fact that their strata are well displayed in wales. the cambrian carries the roman name of wales, and the ordovician and silurian the names of tribes of ancient britons which inhabited the same country. the devonian is named from the english county devon, where its rocks were early studied. the carboniferous was so called from the large amount of coal which it was found to contain in great britain and continental europe. the cambrian =distribution of strata.= the cambrian rocks outcrop in narrow belts about the pre-cambrian areas of eastern canada and the lake superior region, the adirondacks and the green mountains. strips of cambrian formations occupy troughs in the pre-cambrian rocks of new england and the maritime provinces of canada; a long belt borders on the west the crystalline rocks of the blue ridge; and on the opposite side of the continent the cambrian reappears in the mountains of the great basin and the canadian rockies. in the mississippi valley it is exposed in small districts where uplift has permitted the stripping off of younger rocks. although the areas of outcrop are small, we may infer that cambrian rocks were widely deposited over the continent of north america. =physical geography.= the cambrian system of north america comprises three distinct series, the _lower cambrian_, the _middle cambrian_, and the _upper cambrian_, each of which is characterized by its own peculiar fauna. in sketching the outlines of the continent as it was at the beginning of the paleozoic, it must be remembered that wherever the lower cambrian formations now are found was certainly then sea bottom, and wherever the lower cambrian are wanting, and the next formations rest directly on pre-cambrian rocks, was probably then land. [illustration: fig. . hypothetical map of eastern north america at the beginning of cambrian time unshaded areas, probable land] =early cambrian geography.= in this way we know that at the opening of the cambrian two long, narrow mediterranean seas stretched from north to south across the continent. the eastern sea extended from the gulf of st. lawrence down the champlain-hudson valley and thence along the western base of the blue ridge south at least to alabama. the western sea stretched from the canadian rockies over the great basin and at least as far south as the grand canyon of the colorado in arizona. between these mediterraneans lay a great central land which included the pre-cambrian u-shaped area of the laurentian peneplain, and probably extended southward to the latitude of new orleans. to the east lay a land which we may designate as _appalachia_, whose western shore line was drawn along the site of the present blue ridge, but whose other limits are quite unknown. the land of appalachia must have been large, for it furnished a great amount of waste during the entire paleozoic era, and its eastern coast may possibly have lain even beyond the edge of the present continental shelf. on the western side of the continent a narrow land occupied the site of the sierra nevada mountains. thus, even at the beginning of the paleozoic, the continental plateau of north america had already been left by crustal movements in relief above the abysses of the great oceans on either side. the mediterraneans which lay upon it were shallow, as their sediments prove. they were _epicontinental seas_; that is, they rested _upon_ (greek, _epi_) the submerged portion of the continental plateau. we have no proof that the deep ocean ever occupied any part of where north america now is. the middle and upper cambrian strata are found together with the lower cambrian over the area of both the eastern and the western mediterraneans, so that here the sea continued during the entire period. the sediments throughout are those of shoal water. coarse cross-bedded sandstones record the action of strong shifting currents which spread coarse waste near shore and winnowed it of finer stuff. frequent ripple marks on the bedding planes of the strata prove that the loose sands of the sea floor were near enough to the surface to be agitated by waves and tidal currents. sun cracks show that often the outgoing tide exposed large muddy flats to the drying action of the sun. the fossils, also, of the strata are of kinds related to those which now live in shallow waters near the shore. the sediments which gathered in the mediterranean seas were very thick, reaching in places the enormous depth of ten thousand feet. hence the bottoms of these seas were sinking troughs, ever filling with waste from the adjacent land as fast as they subsided. =late cambrian geography.= the formations of the middle and upper cambrian are found resting unconformably on the pre-cambrian rocks from new york westward into minnesota and at various points in the interior, as in missouri and in texas. hence after earlier cambrian time the central land subsided, with much the same effect as if the mississippi valley were now to lower gradually, and the gulf of mexico to spread northward until it entered lake superior. the cambrian seas transgressed the central land and strewed far and wide behind their advancing beaches the sediments of the later cambrian upon an eroded surface of pre-cambrian rocks. the succession of the cambrian formations in north america records many minor oscillations and varying conditions of physical geography; yet on the whole it tells of widening seas and lowering lands. basal conglomerates and coarse sandstones which must have been laid near shore are succeeded by shaly sandstones, sandy shales, and shales. toward the top of the series heavy beds of limestone, extending from the blue ridge to missouri, speak of clear water, and either of more distant shores or of neighboring lands which were worn or sunk so low that for the most part their waste was carried to the sea in solution. in brief, the cambrian was a period of submergence. it began with the larger part of north america emerged as great land masses. it closed with most of the interior of the continental plateau covered with a shallow sea. the life of the cambrian period it is now for the first time that we find preserved in the offshore deposits of the cambrian seas enough remains of animal life to be properly called a fauna. doubtless these remains are only the most fragmentary representation of the life of the time, for the cambrian rocks are very old and have been widely metamorphosed. yet the five hundred and more species already discovered embrace all the leading types of invertebrate life, and are so varied that we must believe that their lines of descent stretch far back into the pre-cambrian past. =plants.= no remains of plants have been found in cambrian strata, except some doubtful markings, as of seaweed. =sponges.= the sponges, the lowest of the multicellular animals, were represented by several orders. their fossils are recognized by the siliceous spicules, which, as in modern sponges, either were scattered through a mass of horny fibers or were connected in a flinty framework. [illustration: fig. . sponge spicules as seen in flint under the microscope] =coelenterates.= this subkingdom includes two classes of interest to the geologist,--the _hydrozoa_, such as the fresh-water hydra and the jellyfish, and the _corals_. both classes existed in the cambrian. [illustration: fig. . graptolites] the hydrozoa were represented not only by jellyfish but also by the _graptolite_, which takes its name from a fancied resemblance of some of its forms to a quill pen. it was a composite animal with a horny framework, the individuals of the colony living in cells strung on one or both sides along a hollow stem, and communicating by means of a common flesh in this central tube. some graptolites were straight, and some curved or spiral; some were single stemmed, and others consisted of several radial stems united. graptolites occur but rarely in the upper cambrian. in the ordovician and silurian they are very plentiful, and at the close of the silurian they pass out of existence, never to return. =corals= are very rarely found in the cambrian, and the description of their primitive types is postponed to later chapters treating of periods when they became more numerous. =echinoderms.= this subkingdom comprises at present such familiar forms as the crinoid, the starfish, and the sea urchin. the structure of echinoderms is radiate. their integument is hardened with plates or particles of carbonate of lime. [illustration: fig. . cystoids, one showing two rudimentary arms] of the free echinoderms, such as the starfish and the sea urchin, the former has been found in the cambrian rocks of europe, but neither have so far been discovered in the strata of this period in north america. the stemmed and lower division of the echinoderms was represented by a primitive type, the _cystoid_, so called from its saclike form, a small globular or ovate "calyx" of calcareous plates, with an aperture at the top for the mouth, inclosed the body of the animal, and was attached to the sea bottom by a short flexible stalk consisting of disks of carbonate of lime held together by a central ligament. =arthropods.= these segmented animals with "jointed feet," as their name suggests, may be divided in a general way into water breathers and air breathers. the first-named and lower division comprises the class of the _crustacea_,--arthropods protected by a hard exterior skeleton, or "crust,"--of which crabs, crayfish, and lobsters are familiar examples. the higher division, that of the air breathers, includes the following classes: spiders, scorpions, centipedes, and insects. =the trilobite.= the aquatic arthropods, the crustacea, culminated before the air breathers; and while none of the latter are found in the cambrian, the former were the dominant life of the time in numbers, in size, and in the variety of their forms. the leading crustacean type is the _trilobite_, which takes its name from the three lobes into which its shell is divided longitudinally. there are also three cross divisions,--the head shield, the tail shield, and between the two the thorax, consisting of a number of distinct and unconsolidated segments. the head shield carries a pair of large, crescentic, compound eyes, like those of the insect. the eye varies greatly in the number of its lenses, ranging from fourteen in some species to fifteen thousand in others. figure , c, is a restoration of the trilobite, and shows the appendages, which are found preserved only in the rarest cases. [illustration: fig. . trilobites a, a cambrian species; b, a devonian species showing eyes; c, restoration of an ordovician species] during the long ages of the cambrian the trilobite varied greatly. again and again new species and genera appeared, while the older types became extinct. for this reason and because of their abundance, trilobites are used in the classification of the cambrian system. the lower cambrian is characterized by the presence of a trilobitic fauna in which the genus olenellus is predominant. this, the _olenellus zone_, is one of the most important platforms in the entire geological series; for, the world over, it marks the beginning of paleozoic time, while all underlying strata are classified as pre-cambrian. the middle cambrian is marked by the genus paradoxides, and the upper cambrian by the genus olenus. some of the cambrian trilobites were giants, measuring as much as two feet long, while others were the smallest of their kind, a fraction of an inch in length. another type of crustacean which lived in the cambrian and whose order is still living is illustrated in figure . [illustration: fig. . a phyllopod] =worms.= trails and burrows of worms have been left on the sea beaches and mud flats of all geological times from the algonkian to the present. =brachiopods.= these soft-bodied animals, with bivalve shells and two interior armlike processes which served for breathing, appeared in the algonkian, and had now become very abundant. the two valves of the brachiopod shell are unequal in size, and in each valve a line drawn from the beak to the base divides the valve into two equal parts (fig. ). it may thus be told from the pelecypod mollusk, such as the clam, whose two valves are not far from equal in size, each being divided into unequal parts by a line dropped from the beak (fig. ). [illustration: fig. . a cambrian articulate brachiopod, orthis] [illustration: fig. . cambrian inarticulate brachiopods a, lingulella; b, discina] brachiopods include two orders. in the most primitive order--that of the _inarticulate_ brachiopods--the two valves are held together only by muscles of the animal, and the shell is horny or is composed of phosphate of lime. the _discina_, which began in the algonkian, is of this type, as is also the _lingulella_ of the cambrian (fig. ). both of these genera have lived on during the millions of years of geological time since their introduction, handing down from generation to generation with hardly any change to their descendants now living off our shores the characters impressed upon them at the beginning. the more highly organized _articulate_ brachiopods have valves of carbonate of lime more securely joined by a hinge with teeth and sockets (fig. ). in the cambrian the inarticulates predominate, though the articulates grow common toward the end of the period. =mollusks.= the three chief classes of mollusks--the _pelecypods_ (represented by the oyster and clam of to-day), the _gastropods_ (represented now by snails, conches, and periwinkles), and the _cephalopods_ (such as the nautilus, cuttlefish, and squids)--were all represented in the cambrian, although very sparingly. [illustration: fig. . a cambrian pelecypod] [illustration: fig. . gastropods] pteropods, a suborder of the gastropods, appeared in this age. their papery shells of carbonate of lime are found in great numbers from this time on. [illustration: fig. . cambrian pteropods] cephalopods, the most highly organized of the mollusks, started into existence, so far as the record shows, toward, the end of the cambrian, with the long extinct _orthoceras_ (_straighthorn_) and the allied genera of its family. the orthoceras had a long, straight, and tapering shell, divided by cross partitions into chambers. the animal lived in the "body chamber" at the larger end, and walled off the other chambers from it in succession during the growth of the shell. a central tube, the _siphuncle_ (_s_, fig. , _b_), passed through from the body chamber to the closed tip of the cone. [illustration: fig. . orthoceras a, fossil; b, restoration] the seashells, both brachiopods and mollusks, are in some respects the most important to the geologist of all fossils. they have been so numerous, so widely distributed, and so well preserved because of their durable shells and their station in growing sediments, that better than any other group of organisms they can be used to correlate the strata of different regions and to mark by their slow changes the advance of geological time. =climate.= the life of cambrian times in different countries contains no suggestion of any marked climatic zones, and as in later periods a warm climate probably reached to the polar regions. chapter xvii the ordovician[ ] and silurian [ ] often known as the lower silurian. the ordovician in north america the ordovician rocks lie conformably on the cambrian. the two periods, therefore, were not parted by any deformation, either of mountain making or of continental uplift. the general submergence which marked the cambrian continued into the succeeding period with little interruption. =subdivisions and distribution of strata.= the ordovician series, as they have been made out in new york, are given for reference in the following table, with the rocks of which they are chiefly composed: hudson ..... shales utica ..... shales trenton ..... limestones chazy ..... limestones calciferous ..... sandy limestones these marine formations of the ordovician outcrop about the cambrian and pre-cambrian areas, and, as borings show, extend far and wide over the interior of the continent beneath more recent strata. the ordovician sea stretched from appalachia across the mississippi valley. it seems to have extended to california, although broken probably by several mountainous islands in the west. =physical geography.= the physical history of the period is recorded in the succession of its formations. the sandstones of the upper cambrian, as we have learned, tell of a transgressing sea which gradually came to occupy the mississippi valley and the interior of north america. the limestones of the early and middle ordovician show that now the shore had become remote and the lands had become more low. the waters now had cleared. colonies of brachiopods and other lime-secreting animals occupied the sea bottom, and their debris mantled it with sheets of limy ooze. the sandy limestones of the calciferous record the transition stage from the cambrian when some sand was still brought in from shore. the highly fossiliferous limestones of the trenton tell of clear water and abundant life. we need not regard this epicontinental sea as deep. no abysmal deposits have been found, and the limestones of the period are those which would be laid in clear, warm water of moderate depth like that of modern coral seas. [illustration: fig. . hypothetical map of the eastern united states in ordovician time shaded areas, probable sea; broken lines, approximate shore lines] the shales of the utica and hudson show that the waters of the sea now became clouded with mud washed in from land. either the land was gradually uplifted, or perhaps there had arrived one of those periodic crises which, as we may imagine, have taken place whenever the crust of the shrinking earth has slowly given way over its great depressions, and the ocean has withdrawn its waters into deepening abysses. the land was thus left relatively higher and bordered with new coastal plains. the epicontinental sea was shoaled and narrowed, and muds were washed in from the adjacent lands. =the taconic deformation.= the ordovician was closed by a deformation whose extent and severity are not yet known. from the st. lawrence river to new york bay, along the northwestern and western border of new england, lies a belt of cambrian-ordovician rocks more than a mile in total thickness, which accumulated during the long ages of those periods in a gradually subsiding trough between the adirondacks and a pre-cambrian range lying west of the connecticut river. but since their deposition these ancient sediments have been crumpled and crushed, broken with great faults, and extensively metamorphosed. the limestones have recrystallized into marbles, among them the famous marbles of vermont; the cambrian sandstones have become quartzites, and the hudson shale has been changed to a schist exposed on manhattan island and northward. in part these changes occurred at the close of the ordovician, for in several places beds of silurian age rest unconformably on the upturned ordovician strata; but recent investigations have made it probable that the crustal movements recurred at later times, and it was perhaps in the devonian and at the close of the carboniferous that the greater part of the deformation and metamorphism was accomplished. as a result of these movements,--perhaps several times repeated,--a great mountain range was upridged, which has been long since leveled by erosion, but whose roots are now visible in the taconic mountains of western new england. =the cincinnati anticline.= over an oval area in ohio, indiana, and kentucky, whose longer axis extends from north to south through cincinnati, the ordovician strata rise in a very low, broad swell, called the cincinnati anticline. the silurian and devonian strata thin out as they approach this area and seem never to have deposited upon it. we may regard it, therefore, as an island upwarped from the sea at the close of the ordovician or shortly after. =petroleum and natural gas.= these valuable illuminants and fuels are considered here because, although they are found in traces in older strata, it is in the ordovician that they occur for the first time in large quantities. they range throughout later formations down to the most recent. [illustration: fig. . diagram illustrating the conditions of accumulation of oil and gas _a_, source; _b_, reservoir; _c_, cover. what would be the result of boring to the reservoir rock at _d_? at _d´_? at _d´´_?] the oil horizons of california and texas are tertiary; those of colorado, cretaceous; those of west virginia, carboniferous; those of pennsylvania, kentucky, and canada, devonian; and the large field of ohio and indiana belongs to the ordovician and higher systems. petroleum and natural gas, wherever found, have probably originated from the decay of organic matter when buried in sedimentary deposits, just as at present in swampy places the hydrogen and carbon of decaying vegetation combine to form marsh gas. the light and heat of these hydrocarbons we may think of, therefore, as a gift to the civilized life of our race from the humble organisms, both animal and vegetable, of the remote past, whose remains were entombed in the sediments of the ordovician and later geological ages. petroleum is very widely disseminated throughout the stratified rocks. certain limestones are visibly greasy with it, and others give off its characteristic fetid odor when struck with a hammer. many shales are bituminous, and some are so highly charged that small flakes may be lighted like tapers, and several gallons of oil to the ton may be obtained by distillation. but oil and gas are found in paying quantities only when certain conditions meet: . a _source_ below, usually a bituminous shale, from whose organic matter they have been derived by slow change. . a _reservoir_ above, in which they have gathered. this is either a porous sandstone or a porous or creviced limestone. . oil and gas are lighter than water, and are usually under pressure owing to artesian water. hence, in order to hold them from escaping to the surface, the reservoir must have the shape of an _anticline_, _dome_, or _lens_. . it must also have an _impervious cover_, usually a shale. in these reservoirs gas is under a pressure which is often enormous, reaching in extreme cases as high as a thousand five hundred pounds to the square inch. when tapped it rushes out with a deafening roar, sometimes flinging the heavy drill high in air. in accounting for this pressure we must remember that the gas has been compressed within the pores of the reservoir rock by artesian water, and in some cases also by its own expansive force. it is not uncommon for artesian water to rise in wells after the exhaustion of gas and oil. _life of the ordovician_ during the ages of the ordovician, life made great advances. types already present branched widely into new genera and species, and new and higher types appeared. sponges continued from the cambrian. graptolites now reached their climax. [illustration: fig. . stromatopora] =stromatopora=--colonies of minute hydrozoans allied to corals--grew in places on the sea floor, secreting stony masses composed of thin, close, concentric layers, connected by vertical rods. the stromatopora are among the chief limestone builders of the silurian and devonian periods. =corals= developed along several distinct lines, like modern corals they secreted a calcareous framework, in whose outer portions the polyps lived. in the ordovician, corals were represented chiefly by the family of the _chætetes_, all species of which are long since extinct. the description of other types of corals will be given under the silurian, where they first became abundant. =echinoderms.= the cystoid reaches its climax, but there appear now two higher types of echinoderms,--the crinoid and the starfish. the _crinoid_, named from its resemblance to the lily, is like the cystoid in many respects, but has a longer stem and supports a crown of plumose arms. stirring the water with these arms, it creates currents by which particles of food are wafted to its mouth. crinoids are rare at the present time, but they grew in the greatest profusion in the warm ordovician seas and for long ages thereafter. in many places the sea floor was beautiful with these graceful, flowerlike forms, as with fields of long-stemmed lilies. of the higher, free-moving classes of the echinoderms, starfish are more numerous than in the cambrian, and sea urchins make their appearance in rare archaic forms. [illustration: fig. . crinoid, a jurassic species] [illustration: fig. . an ordovician starfish] [illustration: fig. . an ordovician sea urchin] [illustration: fig. . eurypterus] =crustaceans.= trilobites now reach their greatest development and more than eleven hundred species have been described from the rocks of this period. it is interesting to note that in many species the segments of the thorax have now come to be so shaped that they move freely on one another. unlike their cambrian ancestors, many of the ordovician trilobites could roll themselves into balls at the approach of danger. it is in this attitude, taken at the approach of death, that trilobites are often found in the ordovician and later rocks. the gigantic crustaceans called the _eurypterids_ were also present in this period (fig. ). the arthropods had now seized upon the land. centipedes and insects of a low type, the earliest known land animals, have been discovered in strata of this system. [illustration: fig. . a bryozoan] =bryozoans.= no fossils are more common in the limestones of the time than the small branching stems and lacelike mats of the bryozoans,--the skeletons of colonies of a minute animal allied in structure to the brachiopod. [illustration: fig. . ordovician brachiopods] =brachiopods.= these multiplied greatly, and in places their shells formed thick beds of coquina. they still greatly surpassed the mollusks in numbers. =cephalopods.= among the mollusks we must note the evolution of the cephalopods. the primitive straight orthoceras has now become abundant. but in addition to this ancestral type there appears a succession of forms more and more curved and closely coiled, as illustrated in figure . the nautilus, which began its course in this period, crawls on the bottom of our present seas. [illustration: fig. . a, cyrtoceras; b, trochoceras; c, lituites] [illustration: fig. . nautilus] =vertebrates.= the most important record of the ordovician is that of the appearance of a new and higher type, with possibilities of development lying hidden in its structure that the mollusk and the insect could never hope to reach. scales and plates of minute fishes found in the ordovician rocks near canon city, colorado, show that the humblest of the vertebrates had already made its appearance. but it is probable that vertebrates had been on the earth for ages before this in lowly types, which, being destitute of hard parts, would leave no record. the silurian the narrowing of the seas and the emergence of the lands which characterized the closing epoch of the ordovician in eastern north america continue into the succeeding period of the silurian. new species appear and many old species now become extinct. =the appalachian region.= where the silurian system is most fully developed, from new york southward along the appalachian mountains, it comprises four series: salina ..... shales, impure limestones, gypsum, salt niagara ..... chiefly limestones clinton ..... sandstones, shales, with some limestones medina ..... conglomerates, sandstones the rocks of these series are shallow-water deposits and reach the total thickness of some five thousand feet. evidently they were laid over an area which was on the whole gradually subsiding, although with various gentle oscillations which are recorded in the different formations. the coarse sands of the heavy medina formations record a period of uplift of the oldland of appalachia, when erosion went on rapidly and coarse waste in abundance was brought down from the hills by swift streams and spread by the waves in wide, sandy flats. as the lands were worn lower the waste became finer, and during an epoch of transition--the clinton--there were deposited various formations of sandstones, shales, and limestones. the niagara limestones testify to a long epoch of repose, when low-lying lands sent little waste down to the sea. the gypsum and salt deposits of the salina show that toward the close of the silurian period a slight oscillation brought the sea floor nearer to the surface, and at the north cut off extensive tracts from the interior sea. in these wide lagoons, which now and then regained access to the open sea and obtained new supplies of salt water, beds of salt and gypsum were deposited as the briny waters became concentrated by evaporation under a desert climate. along with these beds there were also laid shales and impure limestones. in new york the "salt pans" of the salina extended over an area one hundred and fifty miles long from east to west and sixty miles wide, and similar salt marshes occurred as far west as cleveland, ohio, and goderich on lake huron. at ithaca, new york, the series is fifteen hundred feet thick, and is buried beneath an equal thickness of later strata. it includes two hundred and fifty feet of solid salt, in several distinct beds, each sealed within the shales of the series. would you expect to find ancient beds of rock salt inclosed in beds of pervious sandstone? the salt beds of the salina are of great value. they are reached by well borings, and their brines are evaporated by solar heat and by boiling. the rock salt is also mined from deep shafts. similar deposits of salt, formed under like conditions, occur in the rocks of later systems down to the present. the salt beds of texas are permian, those of kansas are permian, and those of louisiana are tertiary. =the mississippi valley.= the heavy near-shore formations of the silurian in the appalachian region thin out toward the west. the medina and the clinton sandstones are not found west of ohio, where the first passes into a shale and the second into a limestone. the niagara limestone, however, spreads from the hudson river to beyond the mississippi, a distance of more than a thousand miles. during the silurian period the mississippi valley region was covered with a quiet, shallow, limestone-making sea, which received little waste from the low lands which bordered it. the probable distribution of land and sea in eastern north america and western europe is shown in figure . the fauna of the interior region and of eastern canada are closely allied with that of western europe, and several species are identical. we can hardly account for this except by a shallow-water connection between the two ancient epicontinental seas. it was perhaps along the coastal shelves of a northern land connecting america and europe by way of greenland and iceland that the migration took place, so that the same species came to live in iowa and in sweden. [illustration: fig. . hypothetical map of parts of north america and europe in silurian time. shaded areas, probably seas; broken lines, approximate shore lines] =the western united states.= so little is found of the rocks of the system west of the missouri river that it is quite probable that the western part of the united states had for the most part emerged from the sea at the close of the ordovician and remained land during the silurian. at the same time the western land was perhaps connected with the eastern land of appalachia across arkansas and mississippi; for toward the south the silurian sediments indicate an approach to shore. _life of the silurian_ in this brief sketch it is quite impossible to relate the many changes of species and genera during the silurian. =corals.= some of the more common types are familiarly known as cup corals, honeycomb corals, and chain corals. in the _cup corals_ the most important feature is the development of radiating vertical partitions, or _septa_, in the cell of the polyp. some of the cup corals grew in hemispherical colonies (fig. ), while many were separate individuals (fig. ), building a single conical, or horn-shaped cell, which sometimes reached the extreme size of a foot in length and two or three inches in diameter. [illustration: fig. . a compound cup coral] [illustration: fig. . a simple cup coral] [illustration: fig. . honeycomb corals] [illustration: fig. . a chain coral] [illustration: fig. . a syringopora coral] _honeycomb corals_ consist of masses of small, close-set prismatic cells, each crossed by horizontal partitions, or _tabulæ_, while the septa are rudimentary, being represented by faintly projecting ridges or rows of spines. _chain corals_ are also marked by tabulæ. their cells form elliptical tubes, touching each other at the edges, and appearing in cross section like the links of a chain. they became extinct at the end of the silurian. the corals of the _syringopora_ family are similar in structure to chain corals, but the tubular columns are connected only in places. [illustration: fig. . a blastoid: a, side view, showing portion of the stem; b, summit of calyx (species carboniferous)] [illustration: fig. . a silurian scorpion] to the echinoderms there is now added the _blastoid_ (bud-shaped). the blastoid is stemmed and armless, and its globular "head" or "calyx," with its five petal-like divisions, resembles a flower bud. the blastoids became more abundant in the devonian, culminated in the carboniferous, and disappeared at the end of the paleozoic. the great eurypterids--some of which were five or six feet in length--and the cephalopods were still masters of the seas. fishes were as yet few and small; trilobites and graptolites had now passed their prime and had diminished greatly in numbers. scorpions are found in this period both in europe and in america. the limestone-making seas of the silurian swarmed with corals, crinoids, and brachiopods. with the end of the silurian period the _age of invertebrates_ comes to a close, giving place to the devonian, the _age of fishes_. [illustration: fig. . block of limestone showing interior casts of _pentamerus oblongus_, a common silurian brachiopod] chapter xviii the devonian in america the silurian is not separated from the devonian by any mountain-making deformation or continental uplift. the one period passed quietly into the other. their conformable systems are so closely related, and the change in their faunas is so gradual, that geologists are not agreed as to the precise horizon which divides them. =subdivisions and physical geography.= the devonian is represented in new york and southward by the following five series. we add the rocks of which they are chiefly composed. chemung ..... sandstones and sandy shales hamilton ..... shales and sandstones corniferous ..... limestones oriskany ..... sandstones helderberg ..... limestones the helderberg is a transition epoch referred by some geologists to the silurian. the thin sandstones of the oriskany mark an epoch when waves worked over the deposits of former coastal plains. the limestones of the corniferous testify to a warm and clear wide sea which extended from the hudson to beyond the mississippi. corals throve luxuriantly, and their remains, with those of mollusks and other lime-secreting animals, built up great beds of limestone. the bordering continents, as during the later silurian, must now have been monotonous lowlands which sent down little of even the finest waste to the sea. in the hamilton the clear seas of the previous epoch became clouded with mud. the immense deposits of coarse sandstones and sandy shales of the chemung, which are found off what was at the time the west coast of appalachia, prove an uplift of that ancient continent. the chemung series extends from the catskill mountains to northeastern ohio and south to northeastern tennessee, covering an area of not less than a hundred thousand square miles. in eastern new york it attains three thousand feet in thickness; in pennsylvania it reaches the enormous thickness of two miles; but it rapidly thins to the west. everywhere the chemung is made of thin beds of rapidly alternating coarse and fine sands and clays, with an occasional pebble layer, and hence is a shallow-water deposit. the fine material has not been thoroughly winnowed from the coarse by the long action of strong waves and tides. the sands and clays have undergone little more sorting than is done by rivers. we must regard the chemung sandstones as deposits made at the mouths of swift, turbid rivers in such great amount that they could be little sorted and distributed by waves. over considerable areas the chemung sandstones bear little or no trace of the action of the sea. the catskill mountains, for example, have as their summit layers some three thousand feet of coarse red sandstones of this series, whose structure is that of river deposits, and whose few fossils are chiefly of fresh-water types. the chemung is therefore composed of delta deposits, more or less worked over by the sea. the bulk of the chemung equals that of the sierra nevada mountains. to furnish this immense volume of sediment a great mountain range, or highland, must have been upheaved where the appalachian lowland long had been. to what height the devonian mountains of appalachia attained cannot be told from the volume of the sediments wasted from them, for they may have risen but little faster than they were worn down by denudation. we may infer from the character of the waste which they furnished to the chemung shores that they did not reach an alpine height. the grains of the chemung sandstones are not those which would result from mechanical disintegration, as by frost on high mountain peaks, but are rather those which would be left from the long chemical decay of siliceous crystalline rocks; for the more soluble minerals are largely wanting. the red color of much of the deposits points to the same conclusion. red residual clays accumulated on the mountain sides and upland summits, and were washed as ocherous silt to mingle with the delta sands. the iron-bearing igneous rocks of the oldland also contributed by their decay iron in solution to the rivers, to be deposited in films of iron oxide about the quartz grains of the chemung sandstones, giving them their reddish tints. life of the devonian =plants.= the lands were probably clad with verdure during silurian times, if not still earlier; for some rare remains of ferns and other lowly types of vegetation have been found in the strata of that system. but it is in the devonian that we discover for the first time the remains of extensive and luxuriant forests. this rich flora reached its climax in the carboniferous, and it will be more convenient to describe its varied types in the next chapter. =rhizocarps.= in the shales of the devonian are found microscopic spores of rhizocarps in such countless numbers that their weight must be reckoned in hundreds of millions of tons. it would seem that these aquatic plants culminated in this period, and in widely distant portions of the earth swampy flats and shallow lagoons were filled with vegetation of this humble type, either growing from the bottom or floating free upon the surface. it is to the resinous spores of the rhizocarps that the petroleum and natural gas from devonian rocks are largely due. the decomposition of the spores has made the shales highly bituminous, and the oil and gas have accumulated in the reservoirs of overlying porous sandstones. =invertebrates.= we must pass over the ever-changing groups of the invertebrates with the briefest notice. chain corals became extinct at the close of the silurian, but other corals were extremely common in the devonian seas. at many places corals formed thin reefs, as at louisville, kentucky, where the hardness of the reef rock is one of the causes of the falls of the ohio. sponges, echinoderms, brachiopods, and mollusks were abundant. the cephalopods take a new departure. so far in all their various forms, whether straight, as the orthoceras, or curved, or close-coiled as in the nautilus, the septum, or partition dividing the chambers, met the inner shell along a simple line, like that of the rim of a saucer. there now begins a growth of the septum by which its edges become sharply corrugated, and the suture, or line of juncture of the septum and the shell, is thus angled. the group in which this growth of the septum takes place is called the _goniatite_ (greek _gonia_, angle). [illustration: fig. . a goniatite] =vertebrates.= it is with the greatest interest that we turn now to study the backboned animals of the devonian; for they are believed to be the ancestors of the hosts of vertebrates which have since dominated the earth. their rudimentary structures foreshadowed what their descendants were to be, and give some clue to the earliest vertebrates from which they sprang. like those whose remains are found in the lower paleozoic systems, all of these devonian vertebrates were aquatic and go under the general designation of fishes. the lowest in grade and nearest, perhaps, to the ancestral type of vertebrates, was the problematic creature, an inch or so long, of figure . note the circular mouth not supplied with jaws, the lack of paired fins, and the symmetric tail fin, with the column of cartilaginous, ringlike vertebræ running through it to the end. the animal is probably to be placed with the jawless lampreys and hags,--a group too low to be included among true fishes. [illustration: fig. . palæospondylus] =ostracoderms.= this archaic group, long since extinct, is also too lowly to rank among the true fishes, for its members have neither jaws nor paired fins. these small, fishlike forms were cased in front with bony plates developed in the skin and covered in the rear with scales. the vertebræ were not ossified, for no trace of them has been found. [illustration: fig. . an ostracoderm] =devonian fishes.= the _true fishes_ of the devonian can best be understood by reference to their descendants now living. modern fishes are divided into several groups: _sharks_ and their allies; _dipnoans_; _ganoids_, such as the sturgeon and gar; and _teleosts_,--most common fishes, such as the perch and cod. [illustration: fig. . a paleozoic shark] =sharks.= of all groups of living fishes the sharks are the oldest and still retain most fully the embryonic characters of their paleozoic ancestors. such characters are the cartilaginous skeleton, and the separate gill slits with which the throat wall is pierced and which are arranged in line like the gill openings of the lamprey. the sharks of the silurian and devonian are known to us chiefly by their teeth and fin spines, for they were unprotected by scales or plates, and were devoid of a bony skeleton. figure is a restoration of an archaic shark from a somewhat higher horizon. note the seven gill slits and the lappetlike paired fins. these fins seem to be remnants of the continuous fold of skin which, as embryology teaches, passed from fore to aft down each side of the primitive vertebrate. devonian sharks were comparatively small. they had not evolved into the ferocious monsters which were later to be masters of the seas. [illustration: fig. . a devonian dipnoan] =dipnoans, or lung fishes.= these are represented to-day by a few peculiar fishes and are distinguished by some high structures which ally them with amphibians. an air sac with cellular spaces is connected with the gullet and serves as a rudimentary lung. it corresponds with the swim bladder of most modern fishes, and appears to have had a common origin with it. we may conceive that the primordial fishes not only had gills used in breathing air dissolved in water, but also developed a saclike pouch off the gullet. this sac evolved along two distinct lines. on the line of the ancestry of most modern fishes its duct was closed and it became the swim bladder used in flotation and balancing. on another line of descent it was left open, air was swallowed into it, and it developed into the rudimentary lung of the dipnoans and into the more perfect lungs of the amphibians and other air-breathing vertebrates. one of the ancient dipnoans is illustrated in figure . some of the members of this order were, like the ostracoderms, cased in armor, but their higher rank is shown by their powerful jaws and by other structures. some of these armored fishes reached twenty-five feet in length and six feet across the head. they were the tyrants of the devonian seas. [illustration: fig. . a devonian fringe-finned ganoid] =ganoids.= these take their name from their enameled plates or scales of bone. the few genera now surviving are the descendants of the tribes which swarmed in the devonian seas. a restoration of one of a leading order, the _fringe-finned_ ganoids, is given in figure . the side fins, which correspond to the limbs of the higher vertebrates, are quite unlike those of most modern fishes. their rays, instead of radiating from a common base, fringe a central lobe which contains a cartilaginous axis. the teeth of the devonian ganoids show a complicated folded structure. =general characteristics of devonian fishes.= _the notochord is persistent._ the notochord is a continuous rod of cartilage, or gristle, which in the embryological growth of vertebrate animals supports the spinal nerve cord before the formation of the vertebræ. in most modern fishes and in all higher vertebrates the notochord is gradually removed as the bodies of the vertebræ are formed about it; but in the devonian fishes it persists through maturity and the vertebræ remain incomplete. =the skeleton is cartilaginous.= this also is an embryological characteristic. in the devonian fishes the vertebræ, as well as the other parts of the skeleton, have not ossified, or changed to bone, but remain in their primitive cartilaginous condition. [illustration: fig. . vertebræ of sturgeon in side view _a_; and vertical transverse section _b_, showing notochord _ch_, and neural canal _m_] =the tail fin is vertebrated.= the backbone runs through the fin and is fringed above and below with its vertical rays. in some fishes with vertebrated tail fins the fin is symmetric (fig. ), and this seems to be the primitive type. in others the tail fin is unsymmetric: the backbone runs into the upper lobe, leaving the two lobes of unequal size. in most modern fishes (the _teleosts_) the tail fin is not vertebrated: the spinal column ends in a broad plate, to which the diverging fin rays are attached. but along with these embryonic characters, which were common to all devonian fishes, there were other structures in certain groups which foreshadowed the higher structures of the land vertebrates which were yet to come: air sacs which were to develop into lungs, and cartilaginous axes in the side fins which were a prophecy of limbs. the vertebrates had already advanced far enough to prove the superiority of their type of structure to all others. their internal skeleton afforded the best attachment for muscles and enabled them to become the largest and most powerful creatures of the time. the central nervous system, with the predominance given to the ganglia at the fore end of the nerve cord,--the brain,--already endowed them with greater energy than the invertebrates; and, still more important, these structures contained the possibility of development into the more highly organized land vertebrates which were to rule the earth. =teleosts.= the great group of fishes called the teleosts, or those with complete bony skeletons, to which most modern fishes belong, may be mentioned here, although in the devonian they had not yet appeared. the teleosts are a highly specialized type, adapted most perfectly to their aquatic environment. heavy armor has been discarded, and reliance is placed instead on swiftness. the skeleton is completely ossified and the notochord removed. the vertebræ have been economically withdrawn from the tail, and the cartilaginous axis of the side fins has been found unnecessary. the air sac has become a swim bladder. in this complete specialization they have long since lost the possibility of evolving into higher types. it is interesting to note that the modern teleosts in their embryological growth pass through the stages which characterized the maturity of their devonian ancestors; their skeleton is cartilaginous and their tail fin vertebrated. chapter xix the carboniferous the carboniferous system is so named from the large amount of coal which it contains. other systems, from the devonian on, are coal bearing also, but none so richly and to so wide an extent. never before or since have the peculiar conditions been so favorable for the formation of extensive coal deposits. with few exceptions the carboniferous strata rest on those of the devonian without any marked unconformity; the one period passed quietly into the other, with no great physical disturbances. the carboniferous includes three distinct series. the lower is called the _mississippian_, from the outcrop of its formations along the mississippi river in central and southern illinois and the adjacent portions of iowa and missouri. the middle series is called the _pennsylvanian_ (or coal measures), from its wide occurrence over pennsylvania. the upper series is named the _permian_, from the province of perm in russia. =the mississippian series.= in the interior the mississippian is composed chiefly of limestones, with some shales, which tell of a clear, warm, epicontinental sea swarming with crinoids, corals, and shells, and occasionally clouded with silt from the land. in the eastern region, new york had been added by uplift to the appalachian land which now was united to the northern area. from eastern pennsylvania southward there were laid in a subsiding trough, first, thick sandstones (the pocono sandstone), and later still heavier shales,--the two together reaching the thickness of four thousand feet and more. we infer a renewed uplift of appalachia similar to that of the later epochs of the devonian, but as much less in amount as the volume of sediments is smaller. the pennsylvanian series the mississippian was brought to an end by a quiet oscillation which lifted large areas slightly above the sea, and the pennsylvanian began with a movement in the opposite direction. the sea encroached on the new land, and spread far and wide a great basal conglomerate and coarse sandstones. on this ancient beach deposit a group of strata rests which we must now interpret. they consist of alternating shales and sandstones, with here and there a bed of limestone and an occasional seam of coal. a stratum of fire clay commonly underlies a coal seam, and there occur also beds of iron ore. we give a typical section of a very small portion of the series at a locality in pennsylvania. although some of the minor changes are omitted, the section shows the rapid alternation of the strata: sandstone and shale ..... limestone ..... sandstone ..... coal ..... - shale ..... - sandstone ..... limestone ..... coal ..... - fire clay ..... this section shows more coal than is usual; on the whole, coal seams do not take up more than one foot in fifty of the coal measures. they vary also in thickness more than is seen in the section, some exceptional seams reaching the thickness of fifty feet. =how coal was made.= . coal is of vegetable origin. examined under the microscope even anthracite, or hard coal, is seen to contain carbonized vegetal tissues. there are also all gradations connecting the hardest anthracite--through semibituminous coal, bituminous or soft coal, lignite (an imperfect coal in which sometimes woody fibers may be seen little changed)--with peat and decaying vegetable tissues. coal is compressed and mineralized vegetal matter. its varieties depend on the perfection to which the peculiar change called bituminization has been carried, and also, as shown in the table below, on the degree to which the volatile substances and water have escaped, and on the per cent of carbon remaining. peat bituminous dismal lignite coal anthracite swamp texas penn. penn. moisture . . . . volatile matter . . . . fixed carbon . . . . ash . . . . . the vegetable remains associated with coal are those of land plants. . coal accumulated in the presence of water; for it is only when thus protected from the air that vegetal matter is preserved. . the vegetation of coal accumulated for the most part where it grew; it was not generally drifted and deposited by waves and currents. commonly the fire clay beneath the seam is penetrated with roots, and the shale above is packed with leaves of ferns and other plants as beautifully pressed as in a herbarium. there often is associated with the seam a fossil forest, with the stumps, which are still standing where they grew, their spreading roots, and the soil beneath, all changed to stone. in the nova scotia field, out of seventy-six distinct coal seams, twenty are underlain by old forest grounds. the presence of fire clay beneath a seam points in the same direction. such underclays withstand intense heat and are used in making fire brick, because their alkalies have been removed by the long-continued growth of vegetation. fuel coal is also too pure to have been accumulated by driftage. in that case we should expect to find it mixed with mud, while in fact it often contains no more ash than the vegetal matter would furnish from which it has been compressed. [illustration: fig. . fossil tree stumps of a carboniferous forest, scotland] these conditions are fairly met in the great swamps of river plains and deltas and of coastal plains, such as the great dismal swamp, where thousands of generations of forests with their undergrowths contribute their stems and leaves to form thick beds of peat. a coal seam is a fossil peat bed. =geographical conditions during the pennsylvanian.= the carboniferous peat swamps were of vast extent. a map of the coal measures (fig. ) shows that the coal marshes stretched, with various interruptions of higher ground and straits of open water, from eastern pennsylvania into alabama, texas, and kansas. some individual coal beds may still be traced over a thousand square miles, despite the erosion which they have suffered. it taxes the imagination to conceive that the varied region included within these limits was for hundreds of thousands of years a marshy plain covered with tropical jungles such as that pictured in figure . on the basis that peat loses four fifths of its bulk in changing to coal, we may reckon the thickness of these ancient peat beds. coal seams six and ten feet thick, which are not uncommon, represent peat beds thirty and fifty feet in thickness, while mammoth coal seams fifty feet thick have been compressed from peat beds two hundred and fifty feet deep. at the same time, the thousands of feet of marine and fresh-water sediments, with their repeated alternations of limestones, sandstones, and shales, in which the seams of coal occur, prove a slow subsidence, with many changes in its rate, with halts when the land was at a stillstand, and with occasional movements upward. when subsidence was most rapid and long continued the sea encroached far and wide upon the lowlands and covered the coal swamps with sands and muds and limy oozes. when subsidence slackened or ceased the land gained on the sea. bays were barred, and lagoons as they gradually filled with mud became marshes. river deltas pushed forward, burying with their silts the sunken peat beds of earlier centuries, and at the surface emerged in broad, swampy flats,--like those of the deltas of the mississippi and the ganges,--which soon were covered with luxuriant forests. at times a gentle uplift brought to sea level great coastal plains, which for ages remained mantled with the jungle, their undeveloped drainage clogged with its debris, and were then again submerged. [illustration: fig. . ideal landscape of the pennsylvanian epoch] =physical geography of the several regions.= _the acadian region_ lay on the eastern side of the northern land, where now are new brunswick and nova scotia, and was an immense river delta. here river deposits rich in coal accumulated to a depth of sixteen thousand feet. the area of this coal field is estimated at about thirty-six thousand square miles. _the appalachian region_ skirts the appalachian oldland on the west from the southern boundary of new york to northern alabama, extending west into eastern ohio. the cincinnati anticline was now a peninsula, and the broad gulf which had lain between it and appalachia was transformed at the beginning of the pennsylvanian into wide marshy plains, now sinking beneath the sea and now emerging from it. this area subsided during the carboniferous period to a depth of nearly ten thousand feet. _the central region_ lay west of the peninsula of the cincinnati anticline, and extended from indiana west into eastern nebraska, and from central iowa and illinois southward about the ancient island in missouri and arkansas into oklahoma and texas. on the north the subsidence in this area was comparatively slight, for the carboniferous strata scarcely exceed two thousand feet in thickness. but in arkansas and indian territory the downward movement amounted to four and five miles, as is proved by shoal water deposits of that immense thickness. the coal fields of indiana, and illinois are now separated by erosion from those lying west of the mississippi river. at the south the appalachian land seems still to have stretched away to the west across louisiana and mississippi into texas, and this westward extension formed the southern boundary of the coal marshes of the continent. the three regions just mentioned include the chief carboniferous coal fields of north america. including a field in central michigan evidently formed in an inclosed basin (fig. ), and one in rhode island, the total area of american coal fields has been reckoned at not less than two hundred thousand square miles. we can hardly estimate the value of these great stores of fossil fuel to an industrial civilization. the forests of the coal swamps accumulated in their woody tissues the energy which they received from the sun in light and heat, and it is this solar energy long stored in coal seams which now forms the world's chief source of power in manufacturing. =the western area.= on the great plains beyond the missouri river the carboniferous strata pass under those of more recent systems. where they reappear, as about dissected mountain axes or on stripped plateaus, they consist wholly of marine deposits and are devoid of coal. the rich coal fields of the west are of later date. on the whole the carboniferous seems to have been a time of subsidence in the west. throughout the period a sea covered the great basin and the plateaus of the colorado river. at the time of the greatest depression the sites of the central chains of the rockies were probably islands, but early in the period they may have been connected with the broad lands to the south and east. thousands of feet of carboniferous sediments were deposited where the sierra nevada mountains now stand. =the permian.= as the carboniferous period drew toward its close the sea gradually withdrew from the eastern part of the continent. where the sea lingered in the deepest troughs, and where inclosed basins were cut off from it, the strata of the permian were deposited. such are found in new brunswick, in pennsylvania and west virginia, in texas, and in kansas. in southwestern kansas extensive permian beds of rock salt and gypsum show that here lay great salt lakes in which these minerals were precipitated as their brines grew dense and dried away. in the southern hemisphere the permian deposits are so extraordinary that they deserve a brief notice, although we have so far omitted mention of the great events which characterized the evolution of other continents than our own. the permian fauna-flora of australia, india, south africa, and the southern part of south america are so similar that the inference is a reasonable one that these widely separated regions were then connected together, probably as extensions of a great antarctic continent. interbedded with the permian strata of the first three countries named are extensive and thick deposits of a peculiar nature which are clearly ancient ground moraines. clays and sand, now hardened to firm rock, are inset with unsorted stones of all sizes, which often are faceted and scratched. moreover, these bowlder clays rest on rock pavements which are polished and scored with glacial markings. hence toward the close of the paleozoic the southern lands of the eastern hemisphere were invaded by great glaciers or perhaps by ice sheets like that which now shrouds greenland. these permian ground moraines are not the first traces of the work of glaciers met with in the geological record. similar deposits prove glaciation in norway succeeding the pre-cambrian stage of elevation, and cambrian glacial drift has recently been found in china. =the appalachian deformation.= we have seen that during paleozoic times a long, narrow trough of the sea lay off the western coast of the ancient land of appalachia, where now are the appalachian mountains. during the long ages of this era the trough gradually subsided, although with many stillstands and with occasional slight oscillations upward. meanwhile the land lying to the east was gradually uplifted at varying rates and with long pauses. the waste of the rising land was constantly transferred to the sinking marginal sea bottom, and on the whole the trough was filled with sediments as rapidly as it subsided. the sea was thus kept shallow, and at times, especially toward the close of the era, much of the area was upbuilt or raised to low, marshy, coastal plains. when the carboniferous was ended the waste which had been removed from the land and laid along its margin in the successive formations of the paleozoic had reached a thickness of between thirty and forty thousand feet. both by sedimentation and by subsidence the trough had now become a belt of weakness in the crust of the earth. here the crust was now made of layers to the depth of six or seven miles. in comparison with the massive crystalline rocks of appalachia on the east, the layered rock of the trough was weak to resist lateral pressure, as a ream of sheets of paper is weak when compared with a solid board of the same thickness. it was weaker also than the region to the west, since there the sediments were much thinner. besides, by the long-continued depression the strata of the trough had been bent from the flat-lying attitude in which they were laid to one in which they were less able to resist a horizontal thrust. there now occurred one of the critical stages in the history of the planet, when the crust crumples under its own weight and shrinks down upon a nucleus which is diminishing in volume and no longer able to support it. under slow but resistless pressure the strata of the appalachian trough were thrust against the rigid land, and slowly, steadily bent into long folds whose axes ran northeast-southwest parallel to the ancient coast line. it was on the eastern side next the buttress of the land that the deformation was the greatest, and the folds most steep and close. in central pennsylvania and west virginia the folds were for the most part open. south of these states the folds were more closely appressed, the strata were much broken, and the great thrust faults were formed which have been described already. in eastern pennsylvania seams of bituminous coal were altered to anthracite, while outside the region of strong deformation, as in western pennsylvania, they remained unchanged. an important factor in the deformation was the massive limestones of the cambrian-ordovician. because of these thick, resistant beds the rocks were bent into wide folds and sheared in places with great thrust faults. had the strata been weak shales, an equal pressure would have crushed and mashed them. although the great earth folds were slowly raised, and no doubt eroded in their rising, they formed in all probability a range of lofty mountains, with a width of from fifty to a hundred and twenty-five miles, which stretched from new york to central alabama. from their bases lowlands extended westward to beyond the missouri river. at the same time ranges were upridged out of thick paleozoic sediments both in the bay of fundy region and in the indian territory. the eastern portion of the north american continent was now well-nigh complete. the date of the appalachian deformation is told in the usual way. the carboniferous strata, nearly two miles thick, are all infolded in the appalachian ridges, while the next deposits found in this region--those of the later portion of the first period (the trias) of the succeeding era--rest unconformably on the worn edges of the appalachian folded strata. the deformation therefore took place about the close of the paleozoic. it seems to have begun in the permian, in, eastern pennsylvania,--for here the permian strata are wanting,--and to have continued into the trias, whose earlier formations are absent over all the area. with this wide uplift the subsidence of the sea floor which had so long been general in eastern north america came to an end. deposition now gave place to erosion. the sedimentary record of the paleozoic was closed, and after an unknown lapse of time, here unrecorded, the annals of the succeeding era were written under changed conditions. in western north america the closing stages of the paleozoic were marked by important oscillations. the great basin, which had long been a mediterranean sea, was converted into land over western utah and eastern nevada, while the waves of the pacific rolled across california and western nevada. the absence of tuffs and lavas among the carboniferous strata of north america shows that here volcanic action was singularly wanting during the entire period. even the appalachian deformation was not accompanied by any volcanic outbursts. [illustration: fig. . carboniferous ferns] [illustration: fig. . calamites] life of the carboniferous =plants.= the gloomy forests and dense undergrowths of the carboniferous jungles would appear unfamiliar to us could we see them as they grew, and even a botanist would find many of their forms perplexing and hard to classify. none of our modern trees would meet the eye. plants with conspicuous flowers of fragrance and beauty were yet to come. even mosses and grasses were still absent. tree ferns lifted their crowns of feathery fronds high in air on trunks of woody tissue; and lowly herbaceous ferns, some belonging to existing families, carpeted the ground. many of the fernlike forms, however, have distinct affinities with the cycads, of which they may be the ancestors, and some bear seeds and must be classed as gymnosperms. dense thickets, like cane or bamboo brakes, were composed of thick clumps of _calamites_, whose slender, jointed stems shot up to a height of forty feet, and at the joints bore slender branches set with whorls of leaves. these were close allies of the equiseta or "horsetails," of the present; but they bore characteristics of higher classes in the woody structures of their stems. there were also vast monotonous forests, composed chiefly of trees belonging to the lycopods, and whose nearest relatives to-day are the little club mosses of our eastern woods. two families of lycopods deserve special mention,--the lepidodendrons and the sigillaria. [illustration: fig. . lepidodendron] [illustration: fig. . sigillaria] the _lepidodendron_, or "scale tree," was a gigantic club moss fifty and seventy-five feet high, spreading toward the top into stout branches, at whose ends were borne cone-shaped spore cases. the younger parts of the tree were clothed with stiff needle-shaped leaves, but elsewhere the trunk and branches were marked with scalelike scars, left by the fallen leaves, and arranged in spiral rows. the _sigillaria_, or "seal tree," was similar to the lepidodendron, but its fluted trunk divided into even fewer branches, and was dotted with vertical rows of leaf scars, like the impressions of a seal. both lepidodendron and sigillaria were anchored by means of great cablelike underground stems, which ran to long distances through the marshy ground. the trunks of both trees had a thick woody rind, inclosing loose cellular tissue and a pith. their hollow stumps, filled with sand and mud, are common in the coal measures, and in them one sometimes finds leaves and stems, land shells, and the bones of little reptiles of the time which made their home there. it is important to note that some of these gigantic lycopods, which are classed with the _cryptogams_, or flowerless plants, had pith and medullary rays dividing their cylinders into woody wedges. these characters connect them with the _phanerogams_, or flowering plants. like so many of the organisms of the remote past, they were connecting types from which groups now widely separated have diverged. gymnosperms, akin to the cycads, were also present in the carboniferous forests. such were the different species of _cordaites_, trees pyramidal in shape, with strap-shaped leaves and nutlike fruit. other gymnosperms were related to the yews, and it was by these that many of the fossil nuts found in the coal measures were borne. it is thought by some that the gymnosperms had their station on the drier plains and higher lands. the carboniferous jungles extended over parts of europe and of asia, as well as eastern north america, and reached from the equator to within nine degrees of the north pole. even in these widely separated regions the genera and species of coal plants are close akin and often identical. =invertebrates.= among the echinoderms, crinoids are now exceedingly abundant, sea urchins are more plentiful, and sea cucumbers are found now for the first time. trilobites are rapidly declining, and pass away forever with the close of the period. eurypterids are common; stinging scorpions are abundant; and here occur the first-known spiders. we have seen that the arthropods were the first of all animals to conquer the realm of the air, the earliest insects appearing in the ordovician. insects had now become exceedingly abundant, and the carboniferous forests swarmed with the ancestral types of dragon flies,--some with a spread of wing of more than two feet,--may flies, crickets, and locusts. cockroaches infested the swamps, and one hundred and thirty-three species of this ancient order have been discovered in the carboniferous of north america. the higher flower-loving insects are still absent; the reign of the flowering plants has not yet begun. the paleozoic insects were generalized types connecting the present orders. their fore wings were still membranous and delicately veined, and used in flying; they had not yet become thick, and useful only as wing covers, as in many of their descendants. [illustration: fig. . carboniferous brachiopods _a_, productus; _b_, spirifer, the right-hand figure showing the interior with the calcareous spires for the support of the arms] =fishes= still held to the devonian types, with the exception that the strange ostracoderms now had perished. =amphibians.= the vertebrates had now followed the arthropods and the mollusks upon the land, and developed a higher type adapted to the new environment. amphibians--the class to which frogs and salamanders belong--now appear, with lungs for breathing air and with limbs for locomotion on the land. most of the carboniferous amphibians were shaped like the salamander, with weak limbs adapted more for crawling than for carrying the body well above the ground. some legless, degenerate forms were snakelike in shape. [illustration: fig. . a carboniferous dragon fly one tenth natural size] the earliest amphibians differ from those of to-day in a number of respects. they were connecting types linking together fishes, from which they were descended, with reptiles, of which they were the ancestors. they retained the evidence of their close relationship with the devonian fishes in their cold blood, their gills and aquatic habit during their larval stage, their teeth with dentine infolded like those of the devonian ganoids but still more intricately, and their biconcave vertebræ which never completely ossified. these, the highest vertebrates of the time, had not yet advanced beyond the embryonic stage of the more or less cartilaginous skeleton and the persistent notochord. [illustration: fig. . a carboniferous amphibian] [illustration: fig. . transverse section of segment of tooth of carboniferous amphibian] on the other hand, the skull of the carboniferous amphibians was made of close-set bony plates, like the skull of the reptile, rather than like that of the frog, with its open spaces (figs. and ). unlike modern amphibians, with their slimy skin, the carboniferous amphibians wore an armor of bony scales over the ventral surface and sometimes over the back as well. [illustration: fig. . skull of a permian amphibian from texas] [illustration: fig. . skull of a frog] it is interesting to notice from the footprints and skeletons of these earliest-known vertebrates of the land what was the primitive number of digits. the carboniferous amphibians had five-toed feet, the primitive type of foot, from which their descendants of higher orders, with a smaller number of digits, have diverged. the carboniferous was the age of lycopods and amphibians, as the devonian had been the age of rhizocarps and fishes. =life of the permian.= the close of the paleozoic was, as we have seen, a time of marked physical changes. the upridging of the appalachians had begun and a wide continental uplift--proved by the absence of permian deposits over large areas where sedimentation had gone on before--opened new lands for settlement to hordes of air-breathing animals. changes of climate compelled extensive migrations, and the fauna of different regions were thus brought into conflict. the permian was a time of pronounced changes in plant and animal life, and a transitional period between two great eras. the somber forests of the earlier carboniferous, with their gigantic club mosses, were now replaced by forests of cycads, tree ferns, and conifers. even in the lower permian the lepidodendron and sigillaria were very rare, and before the end of the epoch they and the calamites also had become extinct. gradually the antique types of the paleozoic fauna died out, and in the permian rocks are found the last survivors of the cystoid, the trilobite, and the eurypterid, and of many long-lived families of brachiopods, mollusks, and other invertebrates. the venerable orthoceras and the goniatite linger on through the epoch and into the first period of the succeeding era. forerunners of the great ammonite family of cephalopod mollusks now appear. the antique forms of the earlier carboniferous amphibians continue, but with many new genera and a marked increase in size. a long forward step had now been taken in the evolution of the vertebrates. a new and higher type, the reptiles, had appeared, and in such numbers and variety are they found in the permian strata that their advent may well have occurred in a still earlier epoch. it will be most convenient to describe the permian reptiles along with their descendants of the mesozoic. chapter xx the mesozoic with the close of the permian the world of animal and vegetable life had so changed that the line is drawn here which marks the end of the old order and the beginning of the new and separates the paleozoic from the succeeding era,--the mesozoic, the middle age of geological history. although the mesozoic era is shorter than the paleozoic, as measured by the thickness of their strata, yet its duration must be reckoned in millions of years. its predominant life features are the culmination and the beginning of the decline of reptiles, amphibians, cephalopod mollusks, and cycads, and the advent of marsupial mammals, birds, teleost fishes, and angiospermous plants. the leading events of the long ages of the era we can sketch only in the most summary way. the mesozoic comprises three systems,--the _triassic_, named from its threefold division in germany; the _jurassic_, which is well displayed in the jura mountains; and the _cretaceous_, which contains the extensive chalk (latin, _creta_) deposits of europe. in eastern north america the mesozoic rocks are much less important than the paleozoic, for much of this portion of the continent was land during the mesozoic era, and the area of the mesozoic rocks is small. in western north america, on the other hand, the strata of the mesozoic--and of the cenozoic also--are widely spread. the paleozoic rocks are buried quite generally from view except where the mountain makings and continental uplifts of the mesozoic and cenozoic have allowed profound erosion to bring them to light, as in deep canyons and about mountain axes. the record of many of the most important events in the development of the continent during the mesozoic and cenozoic eras is found in the rocks of our western states. the triassic and jurassic =eastern north america.= the sedimentary record interrupted by the appalachian deformation was not renewed in eastern north america until late in the triassic. hence during this long interval the land stood high, the coast was farther out than now, and over our atlantic states geological time was recorded chiefly in erosion forms of hill and plain which have long since vanished. the area of the later triassic rocks of this region, which take up again the geological record, is seen in the map of figure . they lie on the upturned and eroded edges of the older rocks and occupy long troughs running for the most part parallel to the atlantic coast. evidently subsidence was in progress where these rocks were deposited. the eastern border of appalachia was now depressed. the oldland was warping, and long belts of country lying parallel to the shore subsided, forming troughs in which thousands of feet of sediment now gathered. these triassic rocks, which are chiefly sandstones, hold no marine fossils, and hence were not laid in open arms of the sea. but their layers are often ripple-marked, and contain many tracks of reptiles, imprints of raindrops, and some fossil wood, while an occasional bed of shale is filled with the remains of fishes. we may conceive, then, of the connecticut valley and the larger trough to the southwest as basins gradually sinking at a rate perhaps no faster than that of the new jersey coast to-day, and as gradually aggraded by streams from the neighboring uplands. their broad, sandy flats were overflowed by wandering streams, and when subsidence gained on deposition shallow lakes overspread the alluvial plains. perhaps now and then the basins became long, brackish estuaries, whose low shores were swept by the incoming tide and were in turn left bare at its retreat to receive the rain prints of passing showers and the tracks of the troops of reptiles which inhabited these valleys. the triassic rocks are mainly red sandstones,--often feldspathic, or arkose, with some conglomerates and shales. considering the large amount of feldspathic material in these rocks, do you infer that they were derived from the adjacent crystalline and metamorphic rocks of the oldland of appalachia, or from the sedimentary paleozoic rocks which had been folded into mountains during the appalachian deformation? if from the former, was the drainage of the northern appalachian mountain region then, as now, eastward and southeastward toward the atlantic? the triassic sandstones are voluminous, measuring at least a mile in thickness, and are largely of coarse waste. what do you infer as to the height of the lands from which the waste was shed, or the direction of the oscillation which they were then undergoing? in the southern basins, as about richmond, virginia, are valuable beds of coal; what was the physical geography of these areas when the coal was being formed? [illustration: fig. . section of triassic sandstones of the connecticut valley _ss_, sandstones; _ll_, lava sheets; _cc_, crystalline igneous and metamorphic rocks] interbedded with the triassic sandstones are contemporaneous lava beds which were fed from dikes. volcanic action, which had been remarkably absent in eastern north america during paleozoic times, was well-marked in connection with the warping now in progress. thick intrusive sheets have also been driven in among the strata, as, for example, the sheet of the palisades of the hudson, described on page . the present condition of the triassic sandstones of the connecticut valley is seen in figure . were the beds laid in their present attitude? what was the nature of the deformation which they have suffered? when did the intrusion of lava sheets take place relative to the deformation? what effect have these sheets on the present topography, and why? assuming that the triassic deformation went on more rapidly than denudation, what was its effect on the topography of the time? are there any of its results remaining in the topography of to-day? do the triassic areas now stand higher or lower than the surrounding country, and why? how do the triassic sandstones and shales compare in hardness with the igneous and metamorphic rocks about them? the jurassic strata are wanting over the triassic areas and over all of eastern north america. was this region land or sea, an area of erosion or sedimentation, during the jurassic period? in new jersey, pennsylvania, and farther southwest the lowest strata of the next period, the cretaceous, rest on the eroded edges of the earlier rocks. the surface on which they lie is worn so even that we must believe that at the opening of the cretaceous the oldland of appalachia, including the triassic areas, had been baseleveled at least near the coast. when, therefore, did the deformation of the triassic rocks occur? =western north america.= triassic strata infolded in the sierra nevada mountains carry marine fossils and reach a thickness of nearly five thousand feet. california was then under water, and the site of the sierra was a subsiding trough slowly filling with waste from the great basin land to the east. over a long belt which reaches from wyoming across colorado into new mexico no triassic sediments are found, nor is there any evidence that they were ever present; hence this area was high land suffering erosion during the triassic. on each side of it, in eastern colorado and about the black hills, in western texas, in utah, over the site of the wasatch mountains, and southward into arizona over the plateaus trenched by the colorado river, are large areas of triassic rocks, sandstones chiefly, with some rock salt and gypsum. fossils are very rare and none of them marine. here, then, lay broad shallow lakes often salt, and warped basins, in which the waste of the adjacent uplands gathered. to this system belong the sandstones of the garden of the gods in colorado, which later earth movements have upturned with the uplifted mountain flanks. the jurassic was marked with varied oscillations and wide changes in the outline of sea and land. jurassic shales of immense thickness--now metamorphosed into slates--are found infolded into the sierra nevada mountains. hence during jurassic times the sierra trough continued to subside, and enormous deposits of mud were washed into it from the land lying to the east. contemporaneous lava flows interbedded with the strata show that volcanic action accompanied the downwarp, and that molten rock was driven upward through fissures in the crust and outspread over the sea floor in sheets of lava. =the sierra deformation.= ever since the middle of the silurian, the sierra trough had been sinking, though no doubt with halts and interruptions, until it contained nearly twenty-five thousand feet of sediment. at the close of the jurassic it yielded to lateral pressure and the vast pile of strata was crumpled and upheaved into towering mountains. the mesozoic muds were hardened and squeezed into slates. the rocks were wrenched and broken, and underground waters began the work of filling their fissures with gold-bearing quartz, which was yet to wait millions of years before the arrival of man to mine it. immense bodies of molten rock were intruded into the crust as it suffered deformation, and these appear in the large areas of granite which the later denudation of the range has brought to light. the same movements probably uplifted the rocks of the coast range in a chain of islands. the whole western part of the continent was raised and its seas and lakes were for the most part drained away. =the british isles.= the triassic strata of the british isles are continental, and include breccia beds of cemented talus, deposits of salt and gypsum, and sandstones whose rounded and polished grains are those of the wind-blown sands of deserts. in triassic times the british isles were part of a desert extending over much of northwestern europe. the cretaceous the third great system of the mesozoic includes many formations, marine and continental, which record a long and complicated history marked by great oscillations of the crust and wide changes in the outlines of sea and land. =early cretaceous.= in eastern north america the lowest cretaceous series comprises fresh-water formations which are traced from nantucket across martha's vineyard and long island, and through new jersey southward into georgia. they rest unconformably on the triassic sandstones and the older rocks of the region. the atlantic shore line was still farther out than now in the northern states. again, as during the triassic, a warping of the crust formed a long trough parallel to the coast and to the appalachian ridges, but cut off from the sea; and here the continental deposits of the early cretaceous were laid. along the gulf of mexico the same series was deposited under like conditions over the area known as the mississippi embayment, reaching from georgia northwestward into tennessee and thence across into arkansas and southward into texas. in the southwest the subsidence continued until the transgressing sea covered most of mexico and texas and extended a gulf northward into kansas. in its warm and quiet waters limestones accumulated to a depth of from one thousand to five thousand feet in texas, and of more than ten thousand feet in mexico. meanwhile the lowlands, where the great plains are now, received continental deposits; coal swamps stretched from western montana into british columbia. =the middle cretaceous.= this was a land epoch. the early cretaceous sea retired from texas and mexico, for its sediments are overlain unconformably by formations of the upper cretaceous. so long was the time gap between the two series that no species found in the one occurs in the other. =the upper cretaceous.= there now began one of the most remarkable events in all geological history,--the great cretaceous subsidence. its earlier warpings were recorded in continental deposits,--wide sheets of sandstone, shale, and some coal,--which were spread from texas to british columbia. these continental deposits are overlain by a succession of marine formations whose vast area is shown on the map, figure . we may infer that as the depression of the continent continued the sea came in far and wide over the coast lands and the plains worn low during the previous epochs. upper cretaceous formations show that south of new england the waters of the atlantic somewhat overlapped the crystalline rocks of the piedmont belt and spread their waste over the submerged coastal plain. the gulf of mexico again covered the mississippi embayment, reaching as far north as southern illinois, and extended over texas. a mediterranean sea now stretched from the gulf to the arctic regions and from central iowa to the eastern shore of the great basin land at about the longitude of salt lake city, the colorado mountains rising from it in a chain of islands. along with minor oscillations there were laid in the interior sea various formations of sandstones, shales, and limestones, and from kansas to south dakota beds of white chalk show that the clear, warm waters swarmed at times with foraminiferal life whose disintegrating microscopic shells accumulated in this rare deposit. [illustration: fig. . hypothetical map of upper cretaceous epicontinental seas shaded areas, probable seas; broken lines, approximate shore lines] [illustration: fig. . foraminifera from cretaceous chalk, iowa] at this epoch a wide sea, interrupted by various islands, stretched across eurasia from wales and western spain to china, and spread southward over much of the sahara. to the west its waters were clear and on its floor the crumbled remains of foraminifers gathered in heavy accumulations of calcareous ooze,--the white chalk of france and england. sea urchins were also abundant, and sponges contributed their spicules to form nodules of flint. =the laramie.= the closing stage of the cretaceous was marked in north america by a slow uplift of the land. as the interior sea gradually withdrew, the warping basins of its floor were filled with waste from the rising lands about them, and over this wide area there were spread continental deposits in fresh-water lakes like the great lakes of the present, in brackish estuaries, and in river plains, while occasional oscillations now and again let in the sea. there were vast marshes in which there accumulated the larger part of the valuable coal seams of the west. the laramie is the coal-bearing series of the west, as the pennsylvanian is of the eastern part of our country. =the rocky mountain deformation.= at the close of the cretaceous we enter upon an epoch of mountain-making far more extensive than any which the continent had witnessed. the long belt lying west of the ancient axes of the colorado islands and east of the great basin land had been an area of deposition for many ages, and in its subsiding troughs paleozoic and mesozoic sediments had gathered to the depth of many thousand feet. and now from mexico well-nigh to the arctic ocean this belt yielded to lateral pressure. the cretaceous limestones of mexico were folded into lofty mountains. a massive range was upfolded where the wasatch mountains now are, and various ranges of the rockies in colorado and other states were upridged. however slowly these deformations were effected they were no doubt accompanied by world-shaking earthquakes, and it is known that volcanic eruptions took place on a magnificent scale. outflows of lava occurred along the wasatch, the laccoliths of the henry mountains (p. ) were formed, while the great masses of igneous rock which constitute the cores of the spanish peaks (p. ) and other western mountains were thrust up amid the strata. the high plateaus from which many of these ranges rise had not yet been uplifted, and the bases of the mountains probably stood near the level of the sea. north america was now well-nigh completed. the mediterranean seas which so often had occupied the heart of the land were done away with, and the continent stretched unbroken from the foot of the sierras on the west to the fall line of the atlantic coastal plain on the east. =the mesozoic peneplain.= the immense thickness of the mesozoic formations conveys to our minds some idea of the vast length of time involved in the slow progress of its successive ages. the same lesson is taught as plainly by the amount of denudation which the lands suffered during the era. the beginning of the mesozoic saw a system of lofty mountain ranges stretching from new york into central alabama. the end of this long era found here a wide peneplain crossed by sluggish wandering rivers and overlooked by detached hills as yet unreduced to the general level. the mesozoic era was long enough for the appalachian mountains, upridged at its beginning, to have been weathered and worn away and carried grain by grain to the sea. the same plain extended over southern new england. the taconic range, uplifted partially at least at the close of the ordovician, and the block mountains of the triassic, together with the pre-cambrian mountains of ancient appalachia, had now all been worn to a common level with the allegheny ranges. the mesozoic peneplain has been upwarped by later crustal movements and has suffered profound erosion, but the remnants of it which remain on the upland of southern new england and the even summits of the allegheny ridges suffice to prove that it once existed. the age of the mesozoic peneplain is determined from the fact that the lower tertiary sediments were deposited on its even surface when at the close of the era the peneplain was depressed along its edges beneath the sea. life of the mesozoic =plant life of the triassic and jurassic.= the carboniferous forests of lepidodendrons and sigillarids had now vanished from the earth. the uplands were clothed with conifers, like the araucarian pines of south america and australia. dense forests of tree ferns throve in moist regions, and canebrakes of horsetails of modern type, but with stems reaching four inches in thickness, bordered the lagoons and marshes. cycads were exceedingly abundant. these gymnosperms, related to the pines and spruces in structure and fruiting, but palmlike in their foliage, and uncoiling their long leaves after the manner of ferns, culminated in the jurassic. from the view point of the botanist the mesozoic is the age of cycads, and after this era they gradually decline to the small number of species now existing in tropical latitudes. [illustration: fig. . a living cycad of australia] [illustration: fig. . stem of a mesozoic cycad] =plant life of the cretaceous.= in the lower cretaceous the woodlands continued of much the same type as during the jurassic. the forerunners now appeared of the modern dicotyls (plants with two seed leaves), and in the middle cretaceous the monocotyledonous group of palms came in. palms are so like cycads that we may regard them as the descendants of some cycad type. in the _upper cretaceous_, cycads become rare. the highest types of flowering plants gain a complete ascendency, and forests of modern aspect cover the continent from the gulf of mexico to the arctic ocean. among the kinds of forest trees whose remains are found in the continental deposits of the cretaceous are the magnolia, the myrtle, the laurel, the fig, the tulip tree, the chestnut, the oak, beech, elm, poplar, willow, birch, and maple. forests of eucalyptus grew along the coast of new england, and palms on the pacific shores of british columbia. sequoias of many varieties ranged far into northern canada. in northern greenland there were luxuriant forests of magnolias, figs, and cycads; and a similar flora has been disinterred from the cretaceous rocks of alaska and spitzbergen. evidently the lands within the arctic circle enjoyed a warm and genial climate, as they had done during the paleozoic. greenland had the temperature of cuba and southern florida, and the time was yet far distant when it was to be wrapped in glacier ice. [illustration: fig. . a jurassic long-tailed crustacean] =invertebrates.= during the long succession of the ages of the mesozoic, with their vast geographical changes, there were many and great changes in organisms. species were replaced again and again by others better fitted to the changing environment. during the lower cretaceous alone there were no less than six successive changes in the faunas which inhabited the limestone-making sea which then covered texas. we shall disregard these changes for the most part in describing the life of the era, and shall confine our view to some of the most important advances made in the leading types. stromatopora have disappeared. protozoans and sponges are exceedingly abundant, and all contribute to the making of mesozoic strata. corals have assumed a more modern type. sea urchins have become plentiful; crinoids abound until the cretaceous, where they begin their decline to their present humble station. [illustration: fig. . a fossil crab] [illustration: fig. . cretaceous mollusks _a_, ostrea (oyster); _b_, exogyra; _c_. gryphæa] trilobites and eurypterids are gone. ten-footed crustaceans abound of the primitive long-tailed type (represented by the lobster and the crayfish), and in the jurassic there appears the modern short-tailed type represented by the crabs. the latter type is higher in organization and now far more common. in its embryological development it passes through the long-tailed stage; connecting links in the mesozoic also indicate that the younger type is the offshoot of the older. insects evolve along diverse lines, giving rise to beetles, ants, bees, and flies. brachiopods have dwindled greatly in the number of their species, while mollusks have correspondingly increased. the great oyster family dates from here. cephalopods are now to have their day. the archaic orthoceras lingers on into the triassic and becomes extinct, but a remarkable development is now at hand for the more highly organized descendants of this ancient line. we have noticed that in the devonian the sutures of some of the chambered shells become angled, evolving the goniatite type. the sutures now become lobed and _corrugated_ in _ceratites_. the process was carried still farther, and the sutures were elaborately frilled in the great order of the ammonites. it was in the jurassic that the ammonites reached their height. no fossils are more abundant or characteristic of their age. great banks of their shells formed beds of limestone in warm seas the world over. [illustration: fig. . ceratites] [illustration: fig. . an ammonite a portion of the shell is removed to show frilling of suture] [illustration: fig. . slab of rock covered with ammonites,--a bit of a mesozoic sea bottom] [illustration: fig. . representative species of different families of ammonites] the ammonite stem branched into a most luxuriant variety of forms. the typical form was closely coiled like a nautilus. in others the coil was more or less open, or even erected into a spiral. some were hook-shaped, and there were members of the order in which the shell was straight, and yet retained all the internal structures of its kind. at the end of the mesozoic the entire tribe of ammonites became extinct. the belemnite (greek, _belemnon_, a dart) is a distinctly higher type of cephalopod which appeared in the triassic, became numerous and varied in the jurassic and cretaceous, and died out early in the tertiary. like the squids and cuttlefish, of which it was the prototype, it had an internal calcareous shell. this consisted of a chambered and siphuncled cone, whose point was sheathed in a long solid guard somewhat like a dart. the animal carried an ink sac, and no doubt used it as that of the modern cuttlefish is used,--to darken the water and make easy an escape from foes. belemnites have sometimes been sketched with fossil sepia, or india ink, from their own ink sacs. in the belemnites and their descendants, the squids and cuttlefish, the cephalopods made the radical change from external to the internal shell. they abandoned the defensive system of warfare and boldly took up the offensive. no doubt, like their descendants, the belemnites were exceedingly active and voracious creatures. [illustration: fig. . internal shell of belemnite] =fishes and amphibians.= in the triassic and jurassic, little progress was made among the fishes, and the ganoid was still the leading type. in the cretaceous the teleosts, or bony fishes, made their appearance, while ganoids declined toward their present subordinate place. the amphibians culminated in the triassic, some being formidable creatures as large as alligators. they were still of the primitive paleozoic types. their pygmy descendants of more modern types are not found until later, salamanders appearing first in the cretaceous, and frogs at the beginning of the cenozoic. no remains of amphibians have been discovered in the jurassic. do you infer from this that there were none in existence at that time? reptiles of the mesozoic the great order of reptiles made its advent in the permian, culminated in the triassic and jurassic, and began to decline in the cretaceous. the advance from the amphibian to the reptile was a long forward step in the evolution of the vertebrates. in the reptile the vertebrate skeleton now became completely ossified. gills were abandoned and breathing was by lungs alone. the development of the individual from the egg to maturity was uninterrupted by any metamorphosis, such as that of the frog when it passes from the tadpole stage. yet in advancing from the amphibian to the reptile the evolution of the vertebrate was far from finished. the cold-blooded, clumsy and sluggish, small-brained and unintelligent reptile is as far inferior to the higher mammals, whose day was still to come, as it is superior to the amphibian and the fish. the reptiles of the permian, the earliest known, were much like lizards in form of body. constituting a transition type between the amphibians on the one hand, and both the higher reptiles and the mammals on the other, they retained the archaic biconcave vertebra of the fish and in some cases the persistent notochord, while some of them, the theromorphs, possessed characters allying them with mammals. in these the skull was remarkably similar to that of the carnivores, or flesh-eating mammals, and the teeth, unlike the teeth of any later reptiles, were divisible into incisors, canines, and molars, as are the teeth of mammals (fig. ). [illustration: fig. . skull of a permian theromorph] at the opening of the mesozoic era reptiles were the most highly organized and powerful of any animals on the earth. new ranges of continental extent were opened to them, food was abundant, the climate was congenial, and they now branched into very many diverse types which occupied and ruled all fields,--the land, the air, and the sea. the mesozoic was the age of reptiles. =the ancestry of surviving reptilian types.= we will consider first the evolution of the few reptilian types which have survived to the present. crocodiles, the highest of existing reptiles, are a very ancient order, dating back to the lower jurassic, and traceable to earlier ancestral, generalized forms, from which sprang several other orders also. turtles and tortoises are not found until the early jurassic, when they already possessed the peculiar characteristics which set them off so sharply from other reptiles. they seem to have lived at first in shallow water and in swamps, and it is not until after the end of the mesozoic that some of the order became adapted to life on the land. the largest of all known turtles, _archelon_, whose home was the great interior cretaceous sea, was fully a dozen feet in length and must have weighed at least two tons. the skull alone is a yard long. lizards and snakes do not appear until after the close of the mesozoic, although their ancestral lines may be followed back into the cretaceous. we will now describe some of the highly specialized orders peculiar to the mesozoic. =land reptiles.= the _dinosaurs_ (terrible reptiles) are an extremely varied order which were masters of the land from the late trias until the close of the mesozoic era. some were far larger than elephants, some were as small as cats; some walked on all fours, some were bipedal; some fed on the luxuriant tropical foliage, and others on the flesh of weaker reptiles. they may be classed in three divisions,--the _flesh-eating dinosaurs_, the _reptile-footed dinosaurs_, and the _beaked dinosaurs_,--the latter two divisions being herbivorous. the _flesh-eating dinosaurs_ are the oldest known division of the order, and their characteristics are shown in figure . as a class, reptiles are egg layers (_oviparous_); but some of the flesh-eating dinosaurs are known to have been _viviparous_, i.e. to have brought forth their young alive. this group was the longest-lived of any of the three, beginning in the trias and continuing to the close of the mesozoic era. [illustration: fig. . ceratosaurus] contrast the small fore limbs, used only for grasping, with the powerful hind limbs on which the animal stalked about. some of the species of this group seem to have been able to progress by leaping in kangaroo fashion. notice the sharp claws, the ponderous tail, and the skull set at right angles with the spinal column. the limb bones are hollow. the ceratosaurs reached a length of some fifteen feet, and were not uncommon in colorado and the western lands in jurassic times. [illustration: fig. . diplodocus] the _reptile-footed dinosaurs_ (sauropoda) include some of the biggest brutes which ever trod the ground. one of the largest, whose remains are found entombed in the jurassic rocks of wyoming and colorado, is shown in figure . note the five digits on the hind feet, the quadrupedal gait, the enormous stretch of neck and tail, the small head aligned with the vertebral column. diplodocus was fully sixty-five feet long and must have weighed about twenty tons. the thigh bones of the sauropoda are the largest bones which ever grew. that of a genus allied to the diplodocus measures six feet and eight inches, and the total length of the animal must have been not far from eighty feet, the largest land animal known. the sauropoda became extinct when their haunts along the rivers and lakes of the western plains of jurassic times were invaded by the cretaceous interior sea. the _beaked dinosaurs_ (predentata) were distinguished by a beak sheathed with horn carried in front of the tooth-set jaw, and used, we may imagine, in stripping the leaves and twigs of trees and shrubs. we may notice only two of the most interesting types. [illustration: fig. . stegosaurus] _stegosaurus_ (plated reptile) takes its name from the double row of bony plates arranged along its back. the powerful tail was armed with long spines, and the thick skin was defended with irregular bits of bone implanted in it. the brain of the stegosaur was smaller than that of any land vertebrate, while in the sacrum the nerve canal was enlarged to ten times the capacity of the brain cavity of the skull. despite their feeble wits, this well-armored family lived on through millions of years which intervened between their appearance, at the opening of the jurassic, and the close of the cretaceous, when they became extinct. a less stupid brute than the stegosaur was _triceratops_, the dinosaur of the three horns,--one horn carried on the nose, and a massive pair set over the eyes (fig. ). note the enormous wedge-shaped skull, with its sharp beak, and the hood behind resembling a fireman's helmet. triceratops was fully twenty-five feet long, and of twice the bulk of an elephant. the family appeared in the upper cretaceous and became extinct at its close. their bones are found buried in the fresh-water deposits of the time from colorado to montana and eastward to the dakotas. [illustration: fig. . restoration of triceratops by courtesy of the american museum of natural history] =marine reptiles.= in the ocean, reptiles occupied the place now held by the aquatic mammals, such as whales and dolphins, and their form and structure were similarly modified to suit their environment. in the ichthyosaurus (fish reptile), for example, the body was fishlike in form, with short neck and large, pointed head (fig. ). [illustration: fig. . ichthyosaurus] a powerful tail, whose flukes were set vertical, and the lower one of which was vertebrated, served as propeller, while a large dorsal fin was developed as a cutwater. the primitive biconcave vertebræ of the fish and of the early land vertebrates were retained, and the limbs degenerated into short paddles. the skin of the ichthyosaur was smooth like that of a whale, and its food was largely fish and cephalopods, as the fossil contents of its stomach prove. these sea monsters disported along the pacific shore over northern california in triassic times, and the bones of immense members of the family occur in the jurassic strata of wyoming. like whales and seals, the ichthyosaurs were descended from land vertebrates which had become adapted to a marine habitat. [illustration: fig. . plesiosaurus] _plesiosaurs_ were another order which ranged throughout the mesozoic. descended from small amphibious animals, they later included great marine reptiles, characterized in the typical genus by long neck, snakelike head, and immense paddles. they swam in the cretaceous interior sea of western north america. [illustration: fig. . restoration of a mosasaur] _mosasaurs_ belong to the same order as do snakes and lizards, and are an offshoot of the same ancestral line of land reptiles. these snakelike creatures--which measured as much as forty-five feet in length--abounded in the cretaceous seas. they had large conical teeth, and their limbs had become stout paddles. the lower jaw of the mosasaur was jointed; the quadrate bone, which in all reptiles connects the bone of the lower jaw with the skull, was movable, and as in snakes the lower jaw could be used in thrusting prey down the throat. the family became extinct at the end of the mesozoic, and left no descendants. one may imitate the movement of the lower jaw of the mosasaur by extending the arms, clasping the hands, and bending the elbows. =flying reptiles.= the atmosphere, which had hitherto been tenanted only by insects, was first conquered by the vertebrates in the mesozoic. _pterosaurs_, winged reptiles, whose whole organism was adapted for flight through the air, appeared in the jurassic and passed off the stage of existence before the end of the cretaceous. the bones were hollow, as are those of birds. the sternum, or breastbone, was given a keel for the attachment of the wing muscles. the fifth finger, prodigiously lengthened, was turned backward to support a membrane which was attached to the body and extended to the base of the tail. the other fingers were free, and armed with sharp and delicate claws, as shown in figures and . [illustration: fig. . restoration of a pterosaur] [illustration: fig. . skeletons of pterosaur ornithostoma, _a_, and of the condor, _b_ after lucas] these "dragons of the air" varied greatly in size; some were as small as sparrows, while others surpassed in stretch of wing the largest birds of the present day. they may be divided into two groups. the earliest group comprises genera with jaws set with teeth, and with long tails sometimes provided with a rudderlike expansion at the end. in their successors of the later group the tail had become short, and in some of the genera the teeth had disappeared. among the latest of the flying reptiles was _ornithostoma_ (bird beak), the largest creature which ever flew, and whose remains are imbedded in the offshore deposits of the cretaceous sea which held sway over our western plains. ornithostoma's spread of wings was twenty feet. its bones were a marvel of lightness, the entire skeleton, even in its petrified condition, not weighing more than five or six pounds. the sharp beak, a yard long, was toothless and bird-like, as its name suggests. [illustration: fig. . archæopteryx] =birds.= the earliest known birds are found in the jurassic, and during the remainder of the mesozoic they contended with the flying reptiles for the empire of the air. the first feathered creatures were very different from the birds of to-day. their characteristics prove them an offshoot of the dinosaur line of reptiles. _archæopteryx_ (_ancient bird_) (fig. ) exhibits a strange mingling of bird and reptile. like birds, it was fledged with perfect feathers, at least on wings and tail, but it retained the teeth of the reptile, and its long tail was vertebrated, a pair of feathers springing from each joint. throughout the jurassic and cretaceous the remains of birds are far less common than those of flying reptiles, and strata representing hundreds of thousands of years intervene between archæopteryx and the next birds of which we know, whose skeletons occur in the cretaceous beds of western kansas. =mammals.= so far as the entries upon the geological record show, mammals made their advent in a very humble way during the trias. these earliest of vertebrates which suckle their young were no bigger than young kittens, and their strong affinities with the theromorphs suggest that their ancestors are to be found among some generalized types of that order of reptiles. [illustration: fig. . jawbone of a jurassic mammal] during the long ages of the mesozoic, mammals continued small and few, and were completely dominated by the reptiles. their remains are exceedingly rare, and consist of minute scattered teeth,--with an occasional detached jaw,--which prove them to have been flesh or insect eaters. in the same way their affinities are seen to be with the lowest of mammals,--the _monotremes_ and _marsupials_. the monotremes,--such as the duckbill mole and the spiny ant-eater of australia, reproduce by means of eggs resembling those of reptiles; the marsupials, such as the opossum and the kangaroo, bring forth their young alive, but in a very immature condition, and carry them for some time after birth in the marsupium, a pouch on the ventral side of the body. chapter xxi the tertiary =the cenozoic era.= the last stages of the cretaceous are marked by a decadence of the reptiles. by the end of that period the reptilian forms characteristic of the time had become extinct one after another, leaving to represent the class only the types of reptiles which continue to modern times. the day of the ammonite and the belemnite also now drew to a close, and only a few of these cephalopods were left to survive the period. it is therefore at the close of the cretaceous that the line is drawn which marks the end of the middle age of geology and the beginning of the cenozoic era, the era of modern life,--the age of mammals. in place of the giant reptiles, mammals now become masters of the land, appearing first in generalized types which, during the long ages of the era, gradually evolve to higher forms, more specialized and ever more closely resembling the mammals of the present. in the atmosphere the flying dragons of the mesozoic give place to birds and bats. in the sea, whales, sharks, and teleost fishes of modern types rule in the stead of huge swimming reptiles. the lower vertebrates, the invertebrates of land and sea, and the plants of field and forest take on a modern aspect, and differ little more from those of to-day than the plants and animals of different countries now differ from one another. from the beginning of the cenozoic era until now there is a steadily increasing number of species of animals and plants which have continued to exist to the present time. the cenozoic era comprises two divisions,--the _tertiary_ period and the _quaternary_ period. in the early days of geology the formations of the entire geological record, so far as it was then known, were divided into three groups,--the _primary_, the _secondary_ (now known as the mesozoic), and the _tertiary_, when the third group was subdivided into two systems, the term tertiary was retained for the first system of the two, while the term _quaternary_ was used to designate the second. =divisions of the tertiary.= the formations of the tertiary are grouped in three divisions,--the _pliocene_ (more recent), the _miocene_ (less recent), and the _eocene_ (the dawn of the recent). each of these epochs is long and complex. their various subdivisions are distinguished each by its own peculiar organisms, and the changes of physical geography recorded in their strata. in the rapid view which we are compelled to take we can note only a few of the most conspicuous events of the period. =physical geography of the tertiary in eastern north america.= the tertiary rocks of eastern north america are marine deposits and occupy the coastal lowlands of the atlantic and gulf states (fig. ). in new england, tertiary beds occur on the island of martha's vineyard, but not on the mainland; hence the shore line here stood somewhat farther out than now. from new jersey southward the earliest tertiary sands and clays, still unconsolidated, leave only a narrow strip of the edge of the cretaceous between them and the triassic and crystalline rocks of the piedmont oldland; hence the atlantic shore here stood farther in than now, and at the beginning of the period the present coastal plain was continental delta. a broad belt of tertiary sea-laid limestones, sandstones, and shales surrounds the gulf of mexico and extends northward up the mississippi embayment to the mouth of the ohio river; hence the gulf was then larger than at present, and its waters reached in a broad bay far up the mississippi valley. along the atlantic coast the mesozoic peneplain may be traced shoreward to where it disappears from view beneath an unconformable cover of early tertiary marine strata. the beginning of the tertiary was therefore marked by a subsidence. the wide erosion surface which at the close of the mesozoic lay near sea level where the appalachian mountains and their neighboring plateaus and uplands now stand was lowered gently along its seaward edge beneath the tertiary atlantic to receive a cover of its sediments. as the period progressed slight oscillations occurred from time to time. strips of coastal plain were added to the land, and as early as the close of the miocene the shore lines of the atlantic and gulf states had reached well-nigh their present place. louisiana and florida were the last areas to emerge wholly from the sea,--florida being formed by a broad transverse upwarp of the continental delta at the opening of the miocene, forming first an island, which afterwards was joined to the mainland. =the pacific coast.= tertiary deposits with marine fossils occur along the western foothills of the sierra nevadas, and are crumpled among the mountain masses of the coast ranges; it is hence inferred that the great valley of california was then a border sea, separated from the ocean by a chain of mountainous islands which were upridged into the coast ranges at a still later time. tertiary marine strata are spread over the lower columbia valley and that of puget sound, showing that the pacific came in broadly there. =the interior of the western united states.= the closing stages of the mesozoic were marked, as we have seen, by the upheaval of the rocky mountains and other western ranges. the bases of the mountains are now skirted by widespread tertiary deposits, which form the highest strata of the lofty plateaus from the level of whose summits the mountains rise. like the recent alluvium of the great valley of california (p. ), these deposits imply low-lying lands when they were laid, and therefore at that time the mountains rose from near sea level. but the height at which the tertiary strata now stand--five thousand feet above the sea at denver, and twice that height in the plateaus of southern utah--proves that the plateaus of which the tertiary strata form a part have been uplifted during the cenozoic. during their uplift, warping formed extensive basins both east and west of the rockies, and in these basins stream-swept and lake-laid waste gathered to depths of hundreds and thousands of feet, as it is accumulating at present in the great valley of california and on the river plains of turkestan (p. ). the tertiary river deposits of the high plains have already been described (p. ). how widespread are these ancient river plains and beds of fresh-water lakes may be seen in the map of figure . [illustration: fig. . view in the bad lands of south dakota] =the bad lands.= in several of the western states large areas of tertiary fresh-water deposits have been dissected to a maze of hills whose steep sides are cut with innumerable ravines. the deposits of these ancient river plains and lake beds are little cemented and because of the dryness of the climate are unprotected by vegetation; hence they are easily carved by the wet-weather rills of scanty and infrequent rains. these waterless, rugged surfaces were named by the early french explorers the _bad lands_ because they were found so difficult to traverse. the strata of the bad lands contain vast numbers of the remains of the animals of tertiary times, and the large amount of barren surface exposed to view makes search for fossils easy and fruitful. these desolate tracts are therefore frequently visited by scientific collecting expeditions. =mountain making in the tertiary.= the tertiary period included epochs when the earth's crust was singularly unquiet. from time to time on all the continents subterranean forces gathered head, and the crust was bent and broken and upridged in lofty mountains. the sierra nevada range was formed, as we have seen, by strata crumpling at the end of the jurassic. but since that remote time the upfolded mountains had been worn to plains and hilly uplands, the remnants of whose uplifted erosion surfaces may now be traced along the western mountain slopes. beginning late in the tertiary, the region was again affected by mountain-making movements. a series of displacements along a profound fault on the eastern side tilted the enormous earth block of the sierras to the west, lifting its eastern edge to form the lofty crest and giving to the range a steep eastern front and a gentle descent toward the pacific. the coast ranges also have had a complex history with many vicissitudes. the earliest foldings of their strata belong to the close of the jurassic, but it was not until the end of the miocene that the line of mountainous islands and the heavy sediments which had been deposited on their submerged flanks were crushed into a continuous mountain chain. thick pliocene beds upon their sides prove that they were depressed to near sea level during the later tertiary. at the close of the pliocene the coast ranges rose along with the upheaval of the sierra, and their gradual uplift has continued to the present time. the numerous north-south ranges of the great basin and the mount saint elias range of alaska were also uptilted during the tertiary. during the tertiary period many of the loftiest mountains of the earth--the alps, the apennines, the pyrenees, the atlas, the caucasus, and the himalayas--received the uplift to which they owe most of their colossal bulk and height, as portions of the tertiary sea beds now found high upon their flanks attest. in the himalayas, tertiary marine limestones occur sixteen thousand five hundred feet above sea level. =volcanic activity in the tertiary.= the vast deformations of the tertiary were accompanied on a corresponding scale by outpourings of lava, the outburst of volcanoes, and the intrusion of molten masses within the crust. in the sierra nevadas the miocene river gravels of the valleys of the western slope, with their placer deposits of gold, were buried beneath streams of lava and beds of tuff (fig. ). volcanoes broke forth along the rocky mountains and on the plateaus of utah, new mexico, and arizona. mount shasta and the immense volcanic piles of the cascades date from this period. the mountain basin of the yellowstone park was filled to a depth of several thousand feet with tuffs and lavas, the oldest dating as far back as the beginning of the tertiary. crandall volcano (fig. ) was reared in the miocene and the latest eruptions of the park are far more recent. [illustration: fig. . lava plateau with lava domes in the distance] =the columbia and snake river lavas.= still more important is the plateau of lava, more than two hundred thousand square miles in area, extending from the yellowstone park to the cascade mountains, which has been built from miocene times to the present. over this plateau, which occupies large portions of idaho, washington, and oregon, and extends into northern california and nevada, the country rock is basaltic lava. for thousands of square miles the surface is a lava plain which meets the boundary mountains as a lake or sea meets a rugged and deeply indented coast. the floods of molten rock spread up the mountain valleys for a score of miles and more, the intervening spurs rising above the lava like long peninsulas, while here and there an isolated peak was left to tower above the inundation like an island off a submerged shore. the rivers which drain the plateau--the snake, the columbia, and their tributaries--have deeply trenched it, yet their canyons, which reach the depth of several thousand feet, have not been worn to the base of the lava except near the margin and where they cut the summits of mountains drowned beneath the flood. here and there the plateau has been deformed. it has been upbent into great folds, and broken into immense blocks of bedded lava, forming mountain ranges, which run parallel with the pacific coast line. on the edges of these tilted blocks the thickness of the lava is seen to be fully five thousand feet. the plateau has been built, like that of iceland (p. ), of innumerable overlapping sheets of lava. on the canyon walls they weather back in horizontal terraces and long talus slopes. one may distinguish each successive flow by its dense central portion, often jointed with large vertical columns, and the upper portion with its mass of confused irregular columns and scoriaceous surface. the average thickness of the flows seems to be about seventy-five feet. the plateau was long in building. between the layers are found in places old soil beds and forest grounds and the sediments of lakes. hence the interval between the flows in any locality was sometimes long enough for clays to gather in the lakes which filled depressions in the surface. again and again the surface of the black basalt was reddened by oxidation and decayed to soil, and forests had time to grow upon it before the succeeding inundation sealed the sediments and soils away beneath a sheet of stone. near the edges of the lava plain, rivers from the surrounding mountains spread sheets of sand and gravel on the surface of one flow after another. these pervious sands, interbedded with the lava, become the aquifers of artesian wells. in places the lavas rest on extensive lake deposits, one thousand feet deep, and miocene in age as their fossils prove. it is to the middle tertiary, then, that the earliest flows and the largest bulk of the great inundation belong. so ancient are the latest floods in the columbia basin that they have weathered to a residual yellow clay from thirty to sixty feet in depth and marvelously rich in the mineral substances on which plants feed. in the snake river valley the latest lavas are much younger. their surfaces are so fresh and undecayed that here the effusive eruptions may well have continued to within the period of human history. low lava domes like those of iceland mark where last the basalt outwelled and spread far and wide before it chilled (fig. ). in places small mounds of scoria show that the eruptions were accompanied to a slight degree by explosions of steam. so fluid was this superheated lava that recent flows have been traced for more than fifty miles. the rocks underlying the columbia lavas, where exposed to view, are seen to be cut by numerous great dikes of dense basalt, which mark the fissures through which the molten rock rose to the surface. the tertiary included times of widespread and intense volcanic action in other continents as well as in north america. in europe, vesuvius (p. ) and etna began their career as submarine volcanoes in connection with earth movements which finally lifted pliocene deposits in sicily to their present height,--four thousand feet above the sea. volcanoes broke forth in central france and southern germany, in hungary and the carpathians. innumerable fissures opened in the crust from the north of ireland and the western islands of scotland to the faroes, iceland, and even to arctic greenland; and here great plateaus were built of flows of basalt similar to that of the columbia river. in india, at the opening of the tertiary, there had been an outwelling of basalt, flooding to a depth of thousands of feet two hundred thousand square miles of the northwestern part of the peninsula (fig. ), and similar inundations of lava occurred where are now the table-lands of abyssinia. from the middle tertiary on, asia minor, arabia, and persia were the scenes of volcanic action. in palestine the rise of the uplands of judea at the close of the eocene, and the downfaulting of the jordan valley (p. ) were followed by volcanic outbursts. in comparison with the middle tertiary, the present is a time of volcanic inactivity and repose. [illustration: fig. . map showing the lava sheet (shaded area) of western india] =erosion of tertiary mountains and plateaus.= the mountains and plateaus built at various times during the tertiary and at its commencement have been profoundly carved by erosive agents. the sierra nevada mountains have been dissected on the western slope by such canyons as those of king's river and the yosemite. six miles of strata have been denuded from parts of the wasatch mountains since their rise at the beginning of the era. from the colorado plateaus, whose uplift dates from the same time, there have been stripped off ten thousand feet of strata over thousands of square miles, and the colossal canyon of the colorado has been cut after this great denudation had been mostly accomplished. on the eastern side of the continent, as we have seen, a broad peneplain had been developed by the close of the cretaceous. the remnants of this old erosion surface are now found upwarped to various heights in different portions of its area. in southern new england it now stands fifteen hundred feet above the sea in western massachusetts, declining thence southward and eastward to sea level at the coast. in southwestern virginia it has been lifted to four thousand feet above the sea. manifestly this upwarp occurred since the peneplain was formed; it is later than the mesozoic, and the vast dissection which the peneplain has suffered since its uplift must belong to the successive cycles of cenozoic time. revived by the uplift, the streams of the area trenched it as deeply as its elevation permitted, and reaching grade, opened up wide valleys and new peneplains in the softer rocks. the connecticut valley is tertiary in age, and in the weak triassic sandstones has been widened in places to fifteen miles. dating from the same time are the valleys of the hudson, the susquehanna, the delaware, the potomac, and the shenandoah. in pennsylvania and the states lying to the south the mesozoic peneplain lies along the summits of the mountain ridges. on the surface of this ancient plain, tertiary erosion etched out the beautifully regular pattern of the allegheny mountain ridges and their intervening valleys. the weaker strata of the long, regular folds were eroded into longitudinal valleys, while the hard paleozoic sandstones, such as the medina (p. ) and the pocono (p. ), were left in relief as bold mountain walls whose even crests rise to the common level of the ancient plain. from virginia far into alabama the great appalachian valley was opened to a width in places of fifty miles and more, along a belt of intensely folded and faulted strata where once was the heart of the appalachian mountains. in figure , the summit of the cumberland plateau (ab) marks the level of the mesozoic peneplain, while the lower erosion levels are tertiary and quaternary in age. [illustration: fig. . diagram of the allegheny mountains, pennsylvania from davis' elementary physical geography] life of the tertiary period =vegetation and climate.= the highest plants in structure, the _dicotyls_ (such as our deciduous forest trees) and the _monocotyls_ (represented by the palms), were introduced during the cretaceous. the vegetable kingdom reached its culmination before the animal kingdom, and if the dividing line between the mesozoic and the cenozoic were drawn according to the progress of plant life, the cretaceous instead of the tertiary would be made the opening period of the modern era. the plants of the tertiary belonged, for the most part, to genera now living; but their distribution was very different from that of the flora of to-day. in the earlier tertiary, palms flourished over northern europe, and in the northwestern united states grew the magnolia and laurel, along with the walnut, oak, and elm. even in northern greenland and in spitzbergen there were lakes covered with water lilies and surrounded by forests of maples, poplars, limes, the cypress of our southern states, and noble sequoias similar to the "big trees" and redwoods of california. a warm climate like that of the mesozoic, therefore, prevailed over north america and europe, extending far toward the pole. in the later tertiary the climate gradually became cooler. palms disappeared from europe, and everywhere the aspect of forests and open lands became more like that of to-day. grasses became abundant, furnishing a new food for herbivorous animals. =animal life of the tertiary.= little needs to be said of the tertiary invertebrates, so nearly were they like the invertebrates of the present. even in the eocene, about five per cent of marine shells were of species still living, and in the pliocene the proportion had risen to more than one half. fishes were of modern types. teleosts were now abundant. the ocean teemed with sharks, some of them being voracious monsters seventy-five feet and even more in length, with a gape of jaw of six feet, as estimated by the size of their enormous sharp-edged teeth. snakes are found for the first time in the early tertiary. these limbless reptiles, evolved by degeneration from lizardlike ancestors, appeared in nonpoisonous types scarcely to be distinguished from those of the present day. =mammals of the early tertiary.= the fossils of continental deposits of the earliest eocene show that a marked advance had now been made in the evolution of the mammalia. the higher mammals had appeared, and henceforth the lower mammals--the monotremes and the marsupials--are reduced to a subordinate place. [illustration: fig. . phenacodus] these first true mammals were archaic and generalized in structure. their feet were of the primitive type, with five toes of about equal length. they were also _plantigrades_,--that is, they touched the ground with the sole of the entire foot from toe to heel. no foot had yet become adapted to swift running by a decrease in the number of digits and by lifting the heel and sole so that only the toes touch the ground,--a tread called _digitigrade_. nor was there yet any foot like that of the cats, with sharp retractile claws adapted to seizing and tearing the prey. the forearm and the lower leg each had still two separate bones (ulna and radius, fibula and tibia), neither pair having been replaced with a single strong bone, as in the leg of the horse. the teeth also were primitive in type and of full number. the complex heavy grinders of the horse and elephant, the sharp cutting teeth of the carnivores, and the cropping teeth of the grass eaters were all still to come. phenacodus is a characteristic genus of the early eocene, whose species varied in size from that of a bulldog to that of an animal a little larger than a sheep. its feet were primitive, and their five toes bore nails intermediate in form between a claw and a hoof. the archaic type of teeth indicates that the animal was omnivorous in diet. a cast of the brain cavity shows that, like its associates of the time, its brain was extremely small and nearly smooth, having little more than traces of convolutions. the long ages of the eocene and the following epochs of the tertiary were times of comparatively rapid evolution among the mammalia. the earliest forms evolved along diverging lines toward the various specialized types of hoofed mammals, rodents, carnivores, proboscidians, the primates, and the other mammalian orders as we know them now. we must describe the tertiary mammals very briefly, tracing the lines of descent of only a few of the more familiar mammals of the present. =the horse.= the pedigree of the horse runs back into the early eocene through many genera and species to a five-toed,[ ] short-legged ancestor little bigger than a cat. its descendants gradually increased in stature and became better and better adapted to swift running to escape their foes. the leg became longer, and only the tip of the toes struck the ground. the middle toe (digit number three), originally the longest of the five, steadily enlarged, while the remaining digits dwindled and disappeared. the inner digit, corresponding to the great toe and thumb, was the first to go. next number five, the little finger, was also dropped. by the end of the eocene a three-toed genus of the horse family had appeared, as large as a sheep. the hoof of digit number three now supported most of the weight, but the slender hoofs of digits two and four were still serviceable. in the miocene the stature of the ancestors of the horse increased to that of a pony. the feet were still three-toed, but the side hoofs were now mere dewclaws and scarcely touched the ground. the evolution of the family was completed in the pliocene. the middle toe was enlarged still more, the side toes were dropped, and the palm and foot bones which supported them were reduced to splints. [ ] or, more accurately, with four perfect toes and a rudimentary fifth corresponding to the thumb. [illustration: fig. . development of forefoot (a), the forearm (b), the molar (c), of the horse family] while these changes were in progress the radius and ulna of the fore limb became consolidated to a single bone; and in the hind limb the fibula dwindled to a splint, while the tibia was correspondingly enlarged. the molars, also gradually lengthened, and became more and more complex on their grinding surface; the neck became longer; the brain steadily increased in size and its convolutions became more abundant. the evolution of the horse has made for greater fleetness and intelligence. =the rhinoceros and tapir.= these animals, which are grouped with the horse among the _odd-toed_ (perissodactyl) mammals, are now verging toward extinction. in the rhinoceros, evolution seems to have taken the opposite course from that of the horse. as the animal increased in size it became more clumsy, its limbs became shorter and more massive, and, perhaps because of its great weight, the number of digits were not reduced below the number three. like other large herbivores, the rhinoceros, too slow to escape its enemies by flight, learned to withstand them. it developed as its means of defense a nasal horn. peculiar offshoots of the line appeared at various times in the tertiary. a rhinoceros, semiaquatic in habits, with curved tusks, resembling in aspect the hippopotamus, lived along the water courses of the plains east of the rockies, and its bones are now found by the thousands in the miocene of kansas. another developed along a line parallel to that of the horse, and herds of these light-limbed and swift-footed running rhinoceroses ranged the great plains from the dakotas southward. the tapirs are an ancient family which has changed but little since it separated from the other perissodactyl stocks in the early tertiary. at present, tapirs are found only in south america and southern asia,--a remarkable distribution which we could not explain were it not that the geological record shows that during tertiary times tapirs ranged throughout the northern hemisphere, making their way to south america late in that period. during the pleistocene they became extinct over all the intervening lands between the widely separated regions where now they live. the geographic distribution of animals, as well as their relationships and origins, can be understood only through a study of their geological history. [illustration: fig. . a tertiary mastodon] [illustration: fig. . head of dinothere] =the proboscidians.= this unique order of hoofed mammals, of which the elephant is the sole survivor, has been traced back to the close of the eocene. in the middle and later tertiary it was represented by huge creatures so nearly akin to the mastodons of the pleistocene that they are often included in that genus. the tertiary _mastodon_ was furnished with a long, flexible proboscis, and armed with two pairs of long, straight ivory tusks, the pair of the lower jaw being smaller. the _dinothere_ was a curious offshoot of the line, which developed in the miocene in europe. in this immense proboscidian, whose skull was three feet long, the upper pair of tusks had disappeared, and those of the lower jaw were bent down with a backward curve in walrus fashion. [illustration: fig. . crown of mastodon tooth] in the true _elephants_, which do not appear until near the close of the tertiary, the lower jaw loses its tusks and the grinding teeth become exceedingly complex in structure. the grinding teeth of the mastodon had long roots and low crowns crossed by four or five peaked enameled ridges. in the teeth of the true elephants the crown has become deep, and the ridges of enamel have changed to numerous upright, platelike folds, their interspaces filled with cement. the two genera--mastodon and elephant--are connected by species whose teeth are intermediate in pattern. the proboscidians culminated in the pliocene, when some of the giant elephants reached a height of fourteen feet. [illustration: fig. . tooth of an extinct elephant, the mammoth] [illustration: fig. . evolution of the artiodactyl foot, illustrated by existing families _a_, pig; _b_, roebuck; _c_, sheep; _d_, camel] =the artiodactyls= comprise the hoofed mammalia which have an even number of toes, such as cattle, sheep, and swine. like the perissodactyls, they are descended from the primitive five-toed plantigrade mammals of the lowest eocene. in their evolution, digit number one was first dropped, and the middle pair became larger and more massive, while the side digits, numbers two and five, became shorter, weaker, and less serviceable. the _four-toed artiodactyls_ culminated in the tertiary; at present they are represented only by the hippopotamus and the hog. along the main line of the evolution of the artiodactyls the side toes, digits two and five, disappeared, leaving as proof that they once existed the corresponding bones of palm and sole as splints. the _two-toed artiodactyls_, such as the camels, deer, cattle, and sheep, are now the leading types of the herbivores. _swine and peccaries_ are two branches of a common stock, the first developing in the old world and the second in the new. in the miocene a noticeable offshoot of the line was a gigantic piglike brute, a root eater, with a skull a yard in length, whose remains are now found in colorado and south dakota. =camels and llamas.= the line of camels and llamas developed in north america, where the successive changes from an early eocene ancestor, no larger than a rabbit, are traced step by step to the present forms, as clearly as is the evolution of the horse. in the late miocene some of the ancestral forms migrated to the old world by way of a land connection where bering strait now is, and there gave rise to the camels and dromedaries. others migrated into south america, which had now been connected with our own continent, and these developed into the llamas and guanacos, while those of the race which remained in north america became extinct during the pleistocene. some peculiar branches of the camel stem appeared in north america. in the pliocene arose a llama with the long neck and limbs of a giraffe, whose food was cropped from the leaves and branches of trees. far more generalized in structure was the _oreodon_, an animal related to the camels, but with distinct affinities also with other lines, such as those of the hog and deer. these curious creatures were much like the peccary in appearance, except for their long tails. in the middle eocene they roamed in vast herds from oregon to kansas and nebraska. =the ruminants.= this division of the artiodactyls includes antelopes, deer, oxen, bison, sheep, and goats,--all of which belong to a common stock which took its rise in europe in the upper eocene from ancestral forms akin to those of the camels. in the miocene the evolution of the two-toed artiodactyl foot was well-nigh completed. bonelike growths appeared on the head, and the two groups of the ruminants became specialized,--the deer with bony antlers, shed and renewed each year, and the ruminants with hollow horns, whose two bony knobs upon the skull are covered with permanent, pointed, horny sheaths. the ruminants evolved in the old world, and it was not until the later miocene that the ancestors of the antelope and of some deer found their way to north america. mountain sheep and goats, the bison and most of the deer, did not arrive until after the close of the tertiary, and sheep and oxen were introduced by man. the hoofed mammals of the tertiary included many offshoots from the main lines which we have traced. among them were a number of genera of clumsy, ponderous brutes, some almost elephantine in their bulk. =the carnivores.= the ancestral lines of the families of the flesh eaters--such as the cats (lions, tigers, etc.), the bears, the hyenas, and the dogs (including wolves and foxes)--converge in the creodonts of the early eocene,--an order so generalized that it had affinities not only with the carnivores but also with the insect eaters, the marsupials, and the hoofed mammals as well. from these primitive flesh eaters, with small and simple brains, numerous small teeth, and plantigrade tread, the different families of the carnivores of the present have slowly evolved. =dogs and bears.= the dog family diverged from the creodonts late in the eocene, and divided into two branches, one of which evolved the wolves and the other the foxes. an offshoot gave rise to the family of the bears, and so closely do these two families, now wide apart, approach as we trace them back in tertiary times that the amphicyon, a genus doglike in its teeth and bearlike in other structures, is referred by some to the dog and by others to the bear family. the well-known plantigrade tread of bears is a primitive characteristic which has survived from their creodont ancestry. =cats.= the family of the cats, the most highly specialized of all the carnivores, divided in the tertiary into two main branches. one, the saber-tooth tigers (fig. ), which takes its name from their long, saberlike, sharp-edged upper canine teeth, evolved a succession of genera and species, among them some of the most destructive beasts of prey which ever scourged the earth. they were masters of the entire northern hemisphere during the middle tertiary, but in europe during the pliocene they declined, from unknown causes, and gave place to the other branch of cats,--which includes the lions, tigers, and leopards. in the americas the saber-tooth tigers long survived the epoch. [illustration: fig. . saber-tooth tiger] =marine mammals.= the carnivorous mammals of the sea--whales, seals, walruses, etc.--seem to have been derived from some of the creodonts of the early tertiary by adaptation to aquatic life. whales evolved from some land ancestry at a very early date in the tertiary; in the marine deposits of the eocene are found the bones of the zeuglodon, a whalelike creature seventy feet in length. =primates.= this order, which includes lemurs, monkeys, apes, and man, seems to have sprung from a creodont or insectivorous ancestry in the lower eocene. lemur-like types, with small, smooth brains, were abundant in the united states in the early tertiary, but no primates have been found here in the middle tertiary and later strata. in europe true monkeys were introduced in the miocene, and were abundant until the close of the tertiary, when they were driven from the continent by the increasing cold. =advance of the mammalia during the tertiary.= during the several millions of years comprised in tertiary time the mammals evolved from the lowly, simple types which tenanted the earth at the beginning of the period, into the many kinds of highly specialized mammals of the pleistocene and the present, each with the various structures of the body adapted to its own peculiar mode of life. the swift feet of the horse, the horns of cattle and the antlers of the deer, the lion's claws and teeth, the long incisors of the beaver, the proboscis of the elephant, were all developed in tertiary times. in especial the brain of the tertiary mammals constantly grew larger relatively to the size of body, and the higher portion of the brain--the cerebral lobes--increased in size in comparison with the cerebellum. some of the hoofed mammals now have a brain eight or ten times the size of that of their early tertiary predecessors of equal bulk. nor can we doubt that along with the increasing size of brain went a corresponding increase in the keenness of the senses, in activity and vigor, and in intelligence. chapter xxii the quaternary the last period of geological history, the quaternary, may be said to have begun when all, or nearly all, living species of mollusks and most of the existing mammals had appeared. it is divided into two great epochs. the first, the _pleistocene_ or _glacial epoch_, is marked off from the tertiary by the occupation of the northern parts of north america and europe by vast ice sheets; the second, the _recent epoch_, began with the disappearance of the ice sheets from these continents, and merges into the present time. the pleistocene epoch we now come to an episode of unusual interest, so different was it from most of the preceding epochs and from the present, and so largely has it influenced the conditions of man's life. the records of the glacial epoch are so plain and full that we are compelled to believe what otherwise would seem almost incredible,--that following the mild climate of the tertiary came a succession of ages when ice fields, like that of greenland, shrouded the northern parts of north america and europe and extended far into temperate latitudes. =the drift.= our studies of glaciers have prepared us to decipher and interpret the history of the glacial epoch, as it is recorded in the surface deposits known as the drift. over most of canada and the northern states this familiar formation is exposed to view in nearly all cuttings which pass below the surface soil. the drift includes two distinct classes of deposits,--the unstratified drift laid down by glacier ice, and the stratified drift spread by glacier waters. the materials of the drift are in any given place in part unlike the rock on which it rests. they cannot be derived from the underlying rock by weathering, but have been brought from elsewhere. thus where a region is underlain by sedimentary rocks, as is the drift-covered area from the hudson river to the missouri, the drift contains not only fragments of limestone, sandstone, and shale of local derivation, but also pebbles of many igneous and metamorphic rocks, such as granites, gneisses, schists, dike rocks, quartzites, and the quartz of mineral veins, whose nearest source is the archean area of canada and the states of our northern border. the drift received its name when it was supposed that the formation had been drifted by floods and icebergs from outside sources,--a theory long since abandoned. [illustration: fig. . stratified drift overlaying unstratified drift, massachusetts] the distribution also of the drift points clearly to its peculiar origin. within the limits of the glaciated area it covers the country without regard to the relief, mantling with its debris not only lowlands and valleys but also highlands and mountain slopes. the boundary of the drift is equally independent of the relief of the land, crossing hills and plains impartially, unlike water-laid deposits, whose margins, unless subsequently deformed, are horizontal. the boundary of the drift is strikingly lobate also, bending outward in broad, convex curves, where there are no natural barriers in the topography of the country to set it such a limit. under these conditions such a lobate margin cannot belong to deposits of rivers, lakes, or ocean, but is precisely that which would mark the edge of a continental glacier which deployed in broad tongues of ice. =the rock surface underlying the drift.= over much of its area the drift rests on firm, fresh rock, showing that both the preglacial mantle of residual waste and the partially decomposed and broken rock beneath it have been swept away. the underlying rock, especially if massive, hard, and of a fine grain, has often been ground down to a smooth surface and rubbed to a polish as perfect as that seen on the rock beside an alpine glacier where the ice has recently melted back. frequently it has been worn to the smooth, rounded hummocks known as roches moutonnées, and even rocky hills have been thus smoothed to flowing outlines like roches moutonnées on a gigantic scale. the rock pavement beneath the drift is also marked by long, straight, parallel scorings, varying in size from deep grooves to fine striae as delicate as the hair lines cut by an engraver's needle. where the rock is soft or closely jointed it is often shattered to a depth of several feet beneath the drift, while stony clay has been thrust in among the fragments into which the rock is broken. in the presence of these glaciated surfaces we cannot doubt that the area of the drift has been overridden by vast sheets of ice which, in their steady flow, rasped and scored the rock bed beneath by means of the stones with which their basal layers were inset, and in places plucked and shattered it. =till.= the unstratified portion of the drift consists chiefly of sheets of dense, stony clay called till, which clearly are the ground moraines of ancient continental glaciers. till is an unsorted mixture of materials of all sizes, from fine clay and sand, gravel, pebbles, and cobblestones, to large bowlders. the stones of the till are of many kinds, some having been plucked from the bed rock of the locality where they are found, and others having been brought from outside and often distant places. land ice is the only agent known which can spread unstratified material in such extensive sheets. the _fine material_ of the till comes from two different sources. in part it is derived from old residual clays, which in the making had been leached of the lime and other soluble ingredients of the rock from which they weathered. in part it consists of sound rock ground fine; a drop of acid on fresh, clayey till often proves by brisk effervescence that the till contains much undecayed limestone flour. the ice sheet, therefore, both scraped up the mantle of long-weathered waste which covered the country before its coming, and also ground heavily upon the sound rock underneath, and crushed and wore to rock flour the fragments which it carried. the color of unweathered till depends on that of the materials of which it is composed. where red sandstones have contributed largely to its making, as over the triassic sandstones of the eastern states and the algonkian sandstones about lake superior, the drift is reddish. when derived in part from coaly shales, as over many outcrops of the pennsylvanian, it may when moist be almost black. fresh till is normally a dull gray or bluish, so largely is it made up of the grindings of unoxidized rocks of these common colors. except where composed chiefly of sand or coarser stuff, unweathered till is often exceedingly dense. can you suggest by what means it has been thus compacted? did the ice fields of the glacial epoch bear heavy surface moraines like the medial and lateral moraines of valley glaciers? where was the greater part of the load of these ice fields carried, judging from what you know of the glaciers of greenland? =bowlders of the drift.= the pebbles and bowlders of the drift are in part stream gravels, bowlders of weathering, and other coarse rock waste picked up from the surface of the country by the advancing ice, and in part are fragments plucked from ledges of sound rock after the mantle of waste had been removed. many of the stones of the till are dressed as only glacier ice can do; their sharp edges have been blunted and their sides faceted and scored. we may easily find all stages of this process represented among the pebbles of the till. some are little worn, even on their edges; some are planed and scored on one side only; while some in their long journey have been ground down to many facets and have lost much of their original bulk. evidently the ice played fast and loose with a stone carried in its basal layers, now holding it fast and rubbing it against the rock beneath, now loosening its grasp and allowing the stone to turn. bowlders of the drift are sometimes found on higher ground than their parent ledges. thus bowlders have been left on the sides of mount katahdin, maine, which were plucked from limestone ledges twelve miles distant and three thousand feet lower than their resting place. in other cases stones have been carried over mountain ranges, as in vermont, where pebbles of burlington red sandstone were dragged over the green mountains, three thousand feet in height, and left in the connecticut valley sixty miles away. no other geological agent than glacier ice could do this work. the bowlders of the drift are often large. bowlders ten and twenty feet in diameter are not uncommon, and some are known whose diameter exceeds fifty feet. as a rule the average size of bowlders decreases with increasing distance from their sources. why? =till plains.= the surface of the drift, where left in its initial state, also displays clear proof of its glacial origin. over large areas it is spread in level plains of till, perhaps bowlder-dotted, similar to the plains of stony clay left in spitzbergen by the recent retreat of some of the glaciers of that island. in places the unstratified drift is heaped in hills of various kinds, which we will now describe. [illustration: fig. . map of a portion of a drumlin area near oswego, new york] =drumlins.= drumlins are smooth, rounded hills composed of till, elliptical in base, and having their longer axes parallel to the movement of the ice as shown by glacial scorings. they crowd certain districts in central new york and in southern wisconsin, where they may be counted by the thousands. among the numerous drumlins about boston is historic bunker hill. drumlins are made of ground moraine. they were accumulated and given shape beneath the overriding ice, much as are sand bars in a river, or in some instances were carved, like roches moutonnées, by an ice sheet out of the till left by an earlier ice invasion. =terminal moraines.= the glaciated area is crossed by belts of thickened drift, often a mile or two, and sometimes even ten miles and more, in breadth, which lie transverse to the movement of the ice and clearly are the terminal moraines of ancient ice sheets, marking either the limit of their farthest advance or pauses in their general retreat. [illustration: fig. . terminal moraine, staten island] the surface of these moraines is a jumble of elevations and depressions, which vary from low, gentle swells and shallow sags to sharp hills, a hundred feet or so in height, and deep, steep-sided hollows. such tumultuous hills and hummocks, set with depressions of all shapes, which usually are without outlet and are often occupied by marshes, ponds, and lakes, surely cannot be the work of running water. the hills are heaps of drift, lodged beneath the ice edge or piled along its front. the basins were left among the tangle of morainic knolls and ridges (fig. ) as the margin of the ice moved back and forth. some bowl-shaped basins were made by the melting of a mass of ice left behind by the retreating glacier and buried in its debris. [illustration: fig. . esker, new york] =the stratified drift.= like modern glaciers the ice sheets of the pleistocene were ever being converted into water about their margins. their limits on the land were the lines where their onward flow was just balanced by melting and evaporation. on the surface of the ice along the marginal zone, rivulets no doubt flowed in summer, and found their way through crevasses to the interior of the glacier or to the ground. subglacial streams, like those of the malaspina glacier, issued from tunnels in the ice, and water ran along the melting ice front as it is seen to do about the glacier tongues of greenland. all these glacier waters flowed away down the chief drainage channels in swollen rivers loaded with glacial waste. it is not unexpected therefore that there are found, over all the country where the melting ice retreated, deposits made of the same materials as the till, but sorted and stratified by running water. some of these were deposited behind the ice front in ice-walled channels, some at the edge of the glaciers by issuing streams, and others were spread to long distances in front of the ice edge by glacial waters as they flowed away. _eskers_ are narrow, winding ridges of stratified sand and gravel whose general course lies parallel with the movement of the glacier. these ridges, though evidently laid by running water, do not follow lines of continuous descent, but may be found to cross river valleys and ascend their sides. hence the streams by which eskers were laid did not flow unconfined upon the surface of the ground. we may infer that eskers were deposited in the tunnels and ice-walled gorges of glacial streams before they issued from the ice front. [illustration: fig. . kames, new york] _kames_ are sand and gravel knolls, associated for the most part with terminal moraines, and heaped by glacial waters along the margin of the ice. [illustration: fig. . diagram illustrating the formation of kame terraces _i_, glacier ice; _t_, _t_, terraces] _kame terraces_ are hummocky embankments of stratified drift sometimes found in rugged regions along the sides of valleys. in these valleys long tongues of glacier ice lay slowly melting. glacial waters took their way between the edges of the glaciers and the hillside, and here deposited sand and gravel in rude terraces. _outwash plains_ are plains of sand and gravel which frequently border terminal moraines on their outward face, and were spread evidently by outwash from the melting ice. outwash plains are sometimes pitted by bowl-shaped basins where ice blocks were left buried in the sand by the retreating glacier. _valley trains_ are deposits of stratified drift with which river valleys have been aggraded. valleys leading outward from the ice front were flooded by glacial waters and were filled often to great depths with trains of stream-swept drift. since the disappearance of the ice these glacial flood plains have been dissected by the shrunken rivers of recent times and left on either side the valley in high terraces. valley trains head in morainic plains, and their material grows finer down valley and coarser toward their sources. their gradient is commonly greater than that of the present rivers. =the extent of the drift.= the extent of the drift of north america and its southern limits are best seen in figure . its area is reckoned at about four million square miles. the ice fields which once covered so much of our continent were all together ten times as large as the inland ice of greenland, and about equal to the enormous ice cap which now covers the antartic regions. the ice field of europe was much smaller, measuring about seven hundred and seventy thousand square miles. =centers of dispersion.= the direction of the movement of the ice is recorded plainly in the scorings of the rock surface, in the shapes of glaciated hills, in the axes of drumlins and eskers, and in trains of bowlders, when the ledges from which they were plucked can be discovered. in these ways it has been proved that in north america there were three centers where ice gathered to the greatest depth, and from which it flowed in all directions outward. there were thus three vast ice fields,--one the _cordilleran_, which lay upon the cordilleras of british america; one the _keewatin_, which flowed out from the province of keewatin, west of hudson bay; and one the _labrador_ ice field, whose center of dispersion was on the highlands of the peninsula of labrador. as shown in figure , the western ice field extended but a short way beyond the eastern foothills of the rocky mountains, where perhaps it met the far-traveled ice from the great central field. the keewatin and the labrador ice fields flowed farthest toward the south, and in the mississippi valley the one reached the mouth of the missouri and the other nearly to the mouth of the ohio. in minnesota and wisconsin and northward they merged in one vast field. [illustration: fig. . hypothetical map of the pleistocene ice sheets of north america from salisbury's _glacial geology of new jersey_] the thickness of the ice was so great that it buried the highest mountains of eastern north america, as is proved by the transported bowlders which have been found upon their summits. if the land then stood at its present height above sea level, and if the average slope of the ice were no more than ten feet to the mile,--a slope so gentle that the eye could not detect it and less than half the slope of the interior of the inland ice of greenland,--the ice plateaus about hudson bay must have reached a thickness of at least ten thousand feet. in europe the scandinavian plateau was the chief center of dispersion. at the time of greatest glaciation a continuous field of ice extended from the ural mountains to the atlantic, where, off the coasts of norway and the british isles, it met the sea in an unbroken ice wall. on the south it reached to southern england, belgium, and central germany, and deployed on the eastern plains in wide lobes over poland and central russia (fig. ). [illustration: fig. . hypothetical map of the pleistocene ice sheet of europe] at the same time the alps supported giant glaciers many times the size of the surviving glaciers of to-day, and a piedmont glacier covered the plains of northern switzerland. =the thickness of the drift.= the drift is far from uniform in thickness. it is comparatively thin and scanty over the laurentian highlands and the rugged regions of new england, while from southern new york and ontario westward over the mississippi valley, and on the great western plains of canada, it exceeds an average of one hundred feet over wide areas, and in places has five and six times that thickness. it was to this marginal belt that the ice sheets brought their loads, while northwards, nearer the centers of dispersion, erosion was excessive and deposition slight. =successive ice invasions and their drift sheets.= recent studies of the drift prove that it does not consist of one indivisible formation, but includes a number of distinct drift sheets, each with its own peculiar features. the pleistocene epoch consisted, therefore, of several glacial stages,--during each of which the ice advanced far southward,--together with the intervening interglacial stages when, under a milder climate, the ice melted back toward its sources or wholly disappeared. [illustration: fig. . diagram illustrating criteria by which different drift sheets are distinguished] the evidences of such interglacial stages, and the means by which the different drift sheets are told apart, are illustrated in figure . here the country from n to s is wholly covered by drift, but the drift from n to _m_ is so unlike that from _m_ to s that we may believe it the product of a distinct ice invasion and deposited during another and far later glacial stage. the former drift is very young, for its drainage is as yet immature, and there are many lakes and marshes upon its surface; the latter is far older, for its surface has been thoroughly dissected by its streams. the former is but slightly weathered, while the latter is so old that it is deeply reddened by oxidation and is leached of its soluble ingredients such as lime. the younger drift is bordered by a distinct terminal moraine, while the margin of the older drift is not thus marked. moreover, the two drift sheets are somewhat unlike in composition, and the different proportion of pebbles of the various kinds of rocks which they contain shows that their respective glaciers followed different tracks and gathered their loads from different regions. again, in places beneath the younger drift there is found the buried land surface of an older drift with old soils, forest grounds, and vegetable deposits, containing the remains of animals and plants, which tell of the climate of the interglacial stage in which they lived. by such differences as these the following drift sheets have been made out in america, and similar subdivisions have been recognized in europe.      the wisconsin formation      the iowan formation      the illinoian formation      the kansan formation      the pre-kansan or jerseyan formation in new jersey and pennsylvania the edge of a deeply weathered and eroded drift sheet, the jerseyan, extends beyond the limits of a much younger overlying drift. it may be the equivalent of a deep-buried basal drift sheet found in the mississippi valley beneath the kansan and parted from it by peat, old soil, and gravel beds. the two succeeding stages mark the greatest snowfall of the glacial epoch. in kansan times the keewatin ice field slowly grew southward until it reached fifteen hundred miles from its center of dispersion and extended from the arctic ocean to northeastern kansas. in the illinoian stage the labrador ice field stretched from hudson straits nearly to the ohio river in illinois. in the iowan and the wisconsin, the closing stages of the glacial epoch, the readvancing ice fields fell far short of their former limits in the mississippi valley, but in the eastern states the labrador ice field during wisconsin times overrode for the most part all earlier deposits, and, covering new england, probably met the ocean in a continuous wall of ice which set its bergs afloat from massachusetts to northern labrador. we select for detailed description the kansan and the wisconsin formations as representatives, the one of the older and the other of the younger drift sheets. [illustration: fig. . photograph of relief map of the united states at the time of the wisconsin ice invasion by the courtesy of e. e. howell, washington, d.c.] =the kansan formation.= the kansan drift consists for the most part of a sheet of clayey till carrying smaller bowlders than the later drift. few traces of drumlins, kames, or terminal moraines are found upon the kansan drift, and where thick enough to mask the preexisting surface, it seems to have been spread originally in level plains of till. the initial kansan plain has been worn by running water until there are now left only isolated patches and the narrow strips and crests of the divides, which still rise to the ancient level. the valleys of the larger streams have been opened wide. their well-developed tributaries have carved nearly the entire plain to valley slopes (figs. b, and ). the lakes and marshes which once marked the infancy of the region have long since been effaced. the drift is also deeply weathered. the till, originally blue in color, has been yellowed by oxidation to a depth of ten and twenty feet and even more, and its surface is sometimes rusted to terra-cotta red. to a somewhat less depth it has been leached of its lime and other soluble ingredients. in the weathered zone its pebbles, especially where the till is loose in texture, are sometimes so rotted that granites may be crumbled with the fingers. the kansan drift is therefore old. [illustration: fig. . plain of wisconsin drift, iowa] =the wisconsin formation.= the wisconsin drift sheet is but little weathered and eroded, and therefore is extremely young. oxidation has effected it but slightly, and lime and other soluble plant foods remain undissolved even at the grass roots. its river systems are still in their infancy (fig. , a). swamps and peat bogs are abundant on its undrained surface, and to this drift sheet belong the lake lands of our northern states and of the laurentian peneplain of canada. the lake basins of the wisconsin drift are of several different classes. many are shallow sags in the ground moraine. still more numerous are the lakes set in hollows among the hills of the terminal moraines; such as the thousands of lakelets of eastern massachusetts. indeed, the terminal moraines of the wisconsin drift may often be roughly traced on maps by means of belts of lakes and ponds. some lakes are due to the blockade of ancient valleys by morainic débris, and this class includes many of the lakes of the adirondacks, the mountain regions of new england, and the laurentian area. still other lakes rest in rock basins scooped out by glaciers. in many cases lakes are due to more than one cause, as where preglacial valleys have both been basined by the ice and blockaded by its moraines. the finger lakes of new york, for example, occupy such glacial troughs. massive _terminal moraines_, which mark the farthest limits to which the wisconsin ice advanced, have been traced from cape cod and the islands south of new england, across the appalachians and the mississippi valley, through the dakotas, and far to the north over the plains of british america. where the ice halted for a time in its general retreat, it left _recessional moraines_, as this variety of the terminal moraine is called. the moraines of the wisconsin drift lie upon the country like great festoons, each series of concentric loops marking the utmost advance of broad lobes of the ice margin and the various pauses in their recession. behind the terminal moraines lie wide till plains, in places studded thickly with drumlins, or ridged with an occasional esker. great outwash plains of sand and gravel lie in front of the moraine belts, and long valley trains of coarse gravels tell of the swift and powerful rivers of the time. =the loess of the mississippi valley.= a yellow earth, quite like the loess of china, is laid broadly as a surface deposit over the mississippi valley from eastern nebraska to ohio outside the boundaries of the iowan and the wisconsin drift. much of the loess was deposited in iowan times. it is younger than the earlier drift sheets, for it overlies their weathered and eroded surfaces. it thickens to the iowan drift border, but is not found upon that drift. it is older than the wisconsin, for in many places it passes underneath the wisconsin terminal moraines. in part the loess seems to have been washed from glacial waste and spread in sluggish glacial waters, and in part to have been distributed by the wind from plains of aggrading glacial streams. [illustration: fig. . bank of loess, iowa] =the effects of the ice invasions on rivers.= the repeated ice invasions of the pleistocene profoundly disarranged the drainage systems of our northern states. in some regions the ancient valleys were completely filled with drift. on the withdrawal of the ice the streams were compelled to find their way, as best they could, over a fresh land surface, where we now find them flowing on the drift in young, narrow channels. but hundreds of feet below the ground the well driller and the prospector for coal and oil discover deep, wide, buried valleys cut in rock,--the channels of preglacial and interglacial streams. in places the ancient valleys were filled with drift to a depth of a hundred feet, and sometimes even to a depth of four hundred and five hundred feet. in such valleys, rivers now flow high above their ancient beds of rock on floors of valley drift. many of the valleys of our present rivers are but patchworks of preglacial, interglacial, and postglacial courses (fig. ). here the river winds along an ancient valley with gently sloping sides and a wide alluvial floor perhaps a mile or so in width, and there it enters a young, rock-walled gorge, whose rocky bed may be crossed by ledges over which the river plunges in waterfalls and rapids. [illustration: fig. . preglacial drainage, upper ohio valley after chamberlain and leverett] [illustration: fig. . a patchwork valley _a_ and _a´_, ancient courses still occupied by the river; _b_, postglacial gorge; _c_, ancient course now filled with drift] in such cases it is possible that the river was pushed to one side of its former valley by a lobe of ice, and compelled to cut a new channel in the adjacent uplands. a section of the valley may have been blockaded with morainic waste, and the lake formed behind the barrier may have found outlet over the country to one side of the ancient drift-filled valley. in some instances it would seem that during the waning of the ice sheets, glacial streams, while confined within walls of stagnant ice, cut down through the ice and incised their channels on the underlying country, in some cases being let down on old river courses, and in other cases excavating gorges in adjacent uplands. =pleistocene lakes.= temporary lakes were formed wherever the ice front dammed the natural drainage of the region. some, held in the minor valleys crossed by ice lobes, were small, and no doubt many were too short-lived to leave lasting records. others, long held against the northward sloping country by the retreating ice edge, left in their beaches their clayey beds, and their outlet channels permanent evidences of their area and depth. some of these glacial lakes are thus known to have been larger than any present lake. lake agassiz, named in honor of the author of the theory of continental glaciation, is supposed to have been held by the united front of the keewatin and the labrador ice fields as they finally retreated down the valley of the red river of the north and the drainage basin of lake winnipeg. from first to last lake agassiz covered a hundred and ten thousand square miles in manitoba and the adjacent parts of minnesota and north dakota,--an area larger than all the great lakes combined. it discharged its waters across the divide which held it on the south, and thus excavated the valley of the minnesota river. the lake bed--a plain of till--was spread smooth and level as a floor with lacustrine silts. since lake agassiz vanished with the melting back of the ice beyond the outlet by the nelson river into hudson bay, there has gathered on its floor a deep humus, rich in the nitrogenous elements so needful for the growth of plants, and it is to this soil that the region owes its well-known fertility. =the great lakes.= the basins of the great lakes are broad preglacial river valleys, warped by movements of the crust still in progress, enlarged by the erosive action of lobes of the continental ice sheets, and blockaded by their drift. the complicated glacial and postglacial history of the lakes is recorded in old strand lines which have been traced at various heights about them, showing their areas and the levels at which their waters stood at different times. with the retreat of the lobate wisconsin ice sheet toward the north and east, the southern and western ends of the basins of the great lakes were uncovered first; and here, between the receding ice front and the slopes of land which faced it, lakes gathered which increased constantly in size. the lake which thus came to occupy the western end of the lake superior basin discharged over the divide at duluth down the st. croix river, as an old outlet channel proves; that which held the southern end of the basin of lake michigan sent its overflow across the divide at chicago via the illinois river to the mississippi; the lake which covered the lowlands about the western end of lake erie discharged its waters at fort wayne into the wabash river. the ice still blocked the mohawk and st. lawrence valleys on the east, while on the west it had retreated far to the north. the lakes become confluent in wide expanses of water, whose depths and margins, as shown by their old lake beaches, varied at different times with the position of the confining ice and with warpings of the land. these vast water bodies, which at one or more periods were greater than all the great lakes combined, discharged at various times across the divide at chicago, near syracuse, new york, down the mohawk valley, and by a channel from georgian bay into the ottawa river. last of all the present outlet by the st. lawrence was established. the beaches of the glacial lakes just mentioned are now far from horizontal. that of the lake which occupied the ontario basin has an elevation of three hundred and sixty-two feet above tide at the west and of six hundred and seventy-five feet at the northeast, proving here a differential movement of the land since glacial times amounting to more than three hundred feet. the beaches which mark the successive heights of these glacial lakes are not parallel; hence the warping began before the glacial epoch closed. we have already seen that the canting of the region is still in progress. =the champlain subsidence.= as the glacial epoch approached its end, and the labrador ice field melted back for the last time to near its source, the land on which the ice had lain in eastern north america was so depressed that the sea now spread far and wide up the st. lawrence valley. it joined with lake ontario, and extending down the champlain and hudson valleys, made an island of new england and the maritime provinces of canada. the proofs of this subsidence are found in old sea beaches and sea-laid clays resting on wisconsin till. at montreal such terraces are found six hundred and twenty feet above sea level, and along lake champlain--where the skeleton of a whale was once found among them--at from five hundred to four hundred feet. the heavy delta which the mohawk river built at its mouth in this arm of the sea now stands something more than three hundred feet above sea level. the clays of the champlain subsidence pass under water near the mouth of the hudson, and in northern new jersey they occur two hundred feet below tide. in these elevations we have measures of the warping of the region since glacial times. =the western united states in glacial times.= the western united states was not covered during the pleistocene by any general ice sheet, but all the high ranges were capped with permanent snow and nourished valley glaciers, often many times the size of the existing glaciers of the alps. in almost every valley of the sierras and the rockies the records of these vanished ice streams may be found in cirques, glacial troughs, roches moutonnées, and morainic deposits. it was during the glacial epoch that lakes bonneville and lahontan were established in the great basin, whose climate must then have been much more moist than now. [illustration: fig. . a valley in the driftless area] =the driftless area.= in the upper mississippi valley there is an area of about ten thousand square miles in southwestern wisconsin and the adjacent parts of iowa and minnesota, which escaped the ice invasions. the rocks are covered with residual clays, the product of long preglacial weathering. the region is an ancient peneplain, uplifted and dissected in late tertiary times, with mature valleys whose gentle gradients are unbroken by waterfalls and rapids. thus the driftless area is in strong contrast with the immature drift topography about it, where lakes and waterfalls are common. it is a bit of preglacial landscape, showing the condition of the entire region before the glacial epoch. the driftless area lay to one side of the main track of both the keewatin and the labrador ice fields, and at the north it was protected by the upland south of lake superior, which weakened and retarded the movement of the ice. south of the driftless area the mississippi valley was invaded at different times by ice sheets from the west,--the kansan and the iowan,--and again by the illinoian ice sheet from the east. again and again the mississippi river was pushed to one side or the other of its path. the ancient channel which it held along the illinoian ice front has been traced through southeastern iowa for many miles. [illustration: fig. . cross section of a valley in eastern iowa _a_, country rock; _b_, kansan till; _c_, loess; _t_, terrace of reddish sands and decayed pebbles above reach of present stream; _s_, stream; _fp_, flood plain of _s_. what is the age of rock-cut valley and of the alluvium which partially fills it, compared with that of the kansan till? with that of the loess? give the complete history recorded in the section.] =benefits of glaciation.= like the driftless area, the preglacial surface over which the ice advanced seems to have been well dissected after the late tertiary uplifts, and to have been carved in many places to steep valley slopes and rugged hills. the retreating ice sheets, which left smooth plains and gently rolling country over the wide belt where glacial deposition exceeded glacial erosion, have made travel and transportation easier than they otherwise would have been. the preglacial subsoils were residual clays and sands, composed of the insoluble elements of the country rock of the locality, with some minglings of its soluble parts still undissolved. the glacial subsoils are made of rocks of many kinds, still undecayed and largely ground to powder. they thus contain an inexhaustible store of the mineral foods of plants, and in a form made easily ready for plant use. on the preglacial hillsides the humus layer must have been comparatively thin, while the broad glacial plains have gathered deep black soils, rich in carbon and nitrogen taken from the atmosphere. to these soils and subsoils a large part of the wealth and prosperity of the glaciated regions of our country must be attributed. the ice invasions have also added very largely to the water power of the country. the rivers which in preglacial times were flowing over graded courses for the most part, were pushed from their old valleys and set to flow on higher levels, where they have developed waterfalls and rapids. this power will probably be fully utilized long before the coal beds of the country are exhausted, and will become one of the chief sources of the national wealth. =the recent epoch.= the deposits laid since glacial times graduate into those now forming along the ocean shores, on lake beds, and in river valleys. slow and comparatively slight changes, such as the warpings of the region of the great lakes, have brought about the geographical conditions of the present. the physical history of the recent epoch needs here no special mention. the life of the quaternary during the entire quaternary, invertebrates and plants suffered little change in species,--so slowly are these ancient and comparatively simple organisms modified. the mammalia, on the other hand, have changed much since the beginning of quaternary time: the various species of the present have been evolved, and some lines have become extinct. these highly organized vertebrates are evidently less stable than are lower types of animals, and respond more rapidly to changes in the environment. =pleistocene mammals.= in the pleistocene the mammalia reached their culmination both in size and in variety of forms, and were superior in both these respects to the mammals of to-day. in pleistocene times in north america there were several species of bison,--one whose widespreading horns were ten feet from tip to tip,--a gigantic moose elk, a giant rodent (castoroides) five feet long, several species of musk oxen, several species of horses,--more akin, however, to zebras than to the modern horse,--a huge lion, several saber-tooth tigers, immense edentates of several genera, and largest of all the mastodon and mammoth. [illustration: fig. . megatherium] [illustration: fig. . glyptodon] the largest of the edentates was the megatherium, a. clumsy ground sloth bigger than a rhinoceros. the bones of the megatherium are extraordinarily massive,--the thigh bone being thrice as thick as that of an elephant,--and the animal seems to have been well able to get its living by overthrowing trees and stripping off their leaves. the glyptodon was a mailed edentate, eight feet long, resembling the little armadillo. these edentates survived from tertiary times, and in the warmer stages of the pleistocene ranged north as far as ohio and oregon. the great proboscidians of the glacial epoch were about the size of modern elephants, and somewhat smaller than their ancestral species in the pliocene. the _mastodon_ ranged over all north america south of hudson bay, but had become extinct in the old world at the end of the tertiary. the elephants were represented by the _mammoth_, which roamed in immense herds from our middle states to alaska, and from arctic asia to the mediterranean and atlantic. it is an oft-told story how about a century ago, near the lena river in siberia, there was found the body of a mammoth which had been safely preserved in ice for thousands of years, how the flesh was eaten by dogs and bears, and how the eyes and hoofs and portions of the hide were taken with the skeleton to st. petersburg. since then several other carcasses of the mammoth, similarly preserved in ice, have been found in the same region,--one as recently as . we know from these remains that the animal was clothed in a coat of long, coarse hair, with thick brown fur beneath. [illustration: fig. . skull of musk ox, from pleistocene deposits, iowa] =the distribution of animals and plants.= the distribution of species in the glacial epoch was far different from that of the present. in the glacial stages arctic species ranged south into what are now temperate latitudes. the walrus throve along the shores of virginia and the musk ox grazed in iowa and kentucky. in europe the reindeer and arctic fox reached the pyrenees. during the champlain depression arctic shells lived along the shore of the arm of the sea which covered the st. lawrence valley. in interglacial times of milder climate the arctic fauna-flora retreated, and their places were taken by plants and animals from the south. peccaries, now found in texas, ranged into michigan and new york, while great sloths from south america reached the middle states. interglacial beds at toronto, canada, contain remains of forests of maple, elm, and papaw, with mollusks now living in the mississippi basin. what changes in the forests of your region would be brought about, and in what way, if the climate should very gradually grow colder? what changes if it should grow warmer? on the alps and the highest summits of the white mountains of new england are found colonies of arctic species of plants and insects. how did they come to be thus separated from their home beyond the arctic circle by a thousand miles and more of temperate climate impossible to cross? =man.= along with the remains of the characteristic animals of the time which are now extinct there have been found in deposits of the glacial epoch in the old world relics of pleistocene _man_, his bones, and articles of his manufacture. in europe, where they have best been studied, human relics occur chiefly in peat bogs, in loess, in caverns where man made his home, and in high river terraces sometimes eighty and a hundred feet above the present flood plains of the streams. in order to understand the development of early man, we should know that prehistoric peoples are ranked according to the materials of which their tools were made and the skill shown in their manufacture. there are thus four well-marked stages of human culture preceding the written annals of history:      the iron stage.      the bronze stage.      the neolithic (recent stone) stage.      the paleolithic (ancient stone) stage. in the neolithic stage the use of the metals had not yet been learned, but tools of stone were carefully shaped and polished. to this stage the north american indian belonged at the time of the discovery of the continent. in the paleolithic stage, stone implements were chipped to rude shapes and left unpolished. this, the lowest state of human culture, has been outgrown by nearly every savage tribe now on earth. a still earlier stage may once have existed, when man had not learned so much as to shape his weapons to his needs, but used chance pebbles and rock splinters in their natural forms; of such a stage, however, we have no evidence. [illustration: fig. . paleolithic implement from great britain] =paleolithic man in europe.= it was to the paleolithic stage that the earliest men belonged whose relics are found in europe. they had learned to knock off two-edged flakes from flint pebbles, and to work them into simple weapons. the great discovery had been made that fire could be kindled and made use of, as the charcoal and the stones discolored by heat of their ancient hearths attest. caves and shelters beneath overhanging cliffs were their homes or camping places. paleolithic man was a savage of the lowest type, who lived by hunting the wild beasts of the time. skeletons found in certain caves in belgium and france represent perhaps the earliest race yet found in europe. these short, broad-shouldered men, muscular, with bent knees and stooping gait, low-browed and small of brain, were of little intelligence and yet truly human. the remains of pleistocene man are naturally found either in caverns, where they escaped destruction by the ice sheets, or in deposits outside the glaciated area. in both cases it is extremely difficult, or quite impossible, to assign the remains to definite glacial or interglacial times. their relative age is best told by the fauna with which they are associated. thus the oldest relics of man are found with the animals of the late tertiary or early quaternary, such as a species of hippopotamus and an elephant more ancient than the mammoth. later in age are the remains found along with the mammoth, cave bear and cave hyena, and other animals of glacial time which are now extinct; while more recent still are those associated with the reindeer, which in the last ice invasion roamed widely with the mammoth over central europe. [illustration: fig. . paleolithic sketch on ivory of the mammoth] =the caves of southern france.= these contain the fullest records of the race, much like the eskimos in bodily frame, which lived in western europe at the time of the mammoth and the reindeer. the floors of these caves are covered with a layer of bone fragments, the remains of many meals, and here are found also various articles of handicraft. in this way we know that the savages who made these caves their homes fished with harpoons of bone, and hunted with spears and darts tipped with flint and horn. the larger bones are split for the extraction of the marrow. among such fragments no split human bones are found; this people, therefore, were not cannibals. bone needles imply the art of sewing, and therefore the use of clothing, made no doubt of skins; while various ornaments, such as necklaces of shells, show how ancient is the love of personal adornment. pottery was not yet invented. there is no sign of agriculture. no animals had yet been domesticated; not even man's earliest friend, the dog. certain implements, perhaps used as the insignia of office, suggest a rude tribal organization and the beginnings of the state. the remains of funeral feasts in front of caverns used as tombs point to a religion and the belief in a life beyond the grave. in the caverns of southern france are found also the beginnings of the arts of painting and of sculpture. with surprising skill these paleolithic men sketched on bits of ivory the mammoth with his long hair and huge curved tusks, frescoed their cavern walls with pictures of the bison and other animals, and carved reindeer on their dagger heads. [illustration: fig. . restoration of head of pithecanthropus erectus] =early man on other continents.= paleolithic flints curiously like those of western europe are found also in many regions of the old world,--in india, egypt, and asia minor,--beneath the earliest vestiges of the civilization of those ancient seats, and sometimes associated with the fauna of the glacial epoch. in java there were found in , in strata early quaternary or late pliocene in age, parts of a skeleton of lower grade, if not of greater antiquity, than any human remains now known. _pithecanthropus erectus_, as the creature has been named, walked erect, as its thigh bone shows, but the skull and teeth indicate a close affinity with the ape. in north america there have been reported many finds of human relics in valley trains, loess, old river gravels buried beneath lava flows, and other deposits of supposed glacial age; but in the opinion of some geologists sufficient proof of the existence of man in america in glacial times has not as yet been found. these finds in north america have been discredited for various reasons. some were not made by scientific men accustomed to the closest scrutiny of every detail. some were reported after a number of years, when the circumstances might not be accurately remembered; while in a number of instances it seems possible that the relics might have been worked into glacial deposits by natural causes from the surface. man, we may believe, witnessed the great ice fields of europe, if not of america, and perhaps appeared on earth under the genial climate of preglacial times. nothing has yet been found of the line of man's supposed descent from the primates of the early tertiary, with the possible exception of the java remains just mentioned. the structures of man's body show that he is not descended from any of the existing genera of apes. and although he may not have been exempt from the law of evolution,--that method of creation which has made all life on earth akin,--yet his appearance was an event which in importance ranks with the advent of life upon the planet, and marks a new manifestation of creative energy upon a higher plane. there now appeared intelligence, reason, a moral nature, and a capacity for self-directed progress such as had never been before on earth. =the recent epoch.= the glacial epoch ends with the melting of the ice sheets of north america and europe, and the replacement of the pleistocene mammalian fauna by present species. how gradually the one epoch shades into the other is seen in the fact that the glaciers which still linger in norway and alaska are the lineal descendants or the renewed appearances of the ice fields of glacial times. our science cannot foretell whether all traces of the great ice age are to disappear, and the earth is to enjoy again the genial climate of the tertiary, or whether the present is an interglacial epoch and the northern lands are comparatively soon again to be wrapped in ice. =neolithic man.= the wild paleolithic men vanished from europe with the wild beasts which they hunted, and their place was taken by tribes, perhaps from asia, of a higher culture. the remains of neolithic man are found, much as are those of the north american indians, upon or near the surface, in burial mounds, in shell heaps (the refuse heaps of their settlements), in peat bogs, caves, recent flood-plain deposits, and in the beds of lakes near shore where they sometimes built their dwellings upon piles. the successive stages in european culture are well displayed in the peat bogs of denmark. the lowest layers contain the polished _stone_ implements of neolithic man, along with remains of the _scotch fir_. above are _oak_ trunks with implements of _bronze_, while the higher layers hold _iron_ weapons and the remains of a _beech_ forest. neolithic man in europe had learned to make pottery, to spin and weave linen, to hew timbers and build boats, and to grow wheat and barley. the dog, horse, ox, sheep, goat, and hog had been domesticated, and, as these species are not known to have existed before in europe, it is a fair inference that they were brought by man from another continent of the old world. neolithic man knew nothing of the art of extracting the metals from their ores, nor had he a written language. the neolithic stage of culture passes by insensible gradations into that of the age of bronze, and thus into the recent epoch. in the recent epoch the progress of man in language, in social organization, in the arts of life, in morals and religion, has left ample records which are for other sciences than ours to read; here, therefore, geology gives place to archæology and history. our brief study of the outlines of geology has given us, it is hoped, some great and lasting good. to conceive a past so different from the present has stimulated the imagination, and to follow the inferences by which the conclusions of our science have been reached has exercised one of the noblest faculties of the mind,--the reason. we have learned to look on nature in new ways: every landscape, every pebble now has a meaning and tells something of its origin and history, while plants and animals have a closer interest since we have traced the long lines of their descent. the narrow horizons of human life have been broken through, and we have caught glimpses of that immeasurable reach of time in which nebulae and suns and planets run their courses. moreover, we have learned something of that orderly and world-embracing progress by which the once uninhabitable globe has come to be man's well-appointed home, and life appearing in the lowliest forms has steadily developed higher and still higher types. seeing this process enter human history and lift our race continually to loftier levels, we find reason to believe that the onward, upward movement of the geological past is the manifestation of the same wise power which makes for righteousness and good and that this unceasing purpose will still lead on to nobler ends. index aa, lava, acadian coal field, accretion hypothesis, acidic rocks, adelsberg grotto, adirondacks, , africa, agassiz, lake, , , agates, alabama, , alaska, , , , aletsch glacier, algæ, , algonkian era, , allegheny mountains, , , , alluvial cones, alluvium, alps, , , , , , , , , , , amazon river, ammonites, , , , amphibians, , amphicyon, amygdules, andes, , angle of repose, antarctic continent, antecedent streams, antelope, anthracite, anticlinal folds, , ants, apennine mountains, appalachia, , , appalachian coal field, appalachian deformation, appalachian mountains, , , , aquifer, aragonite, archæopteryx, archean era, arenaceous rocks, argillaceous rocks, arizona, , , , , , , , , , , arkansas, , , arkose, , , artesian wells, arthropods, artiodactyls, assiniboine, mount, atlas mountains, atmosphere, , atolls, , augite, austin, tex., australia, , avalanches, bad lands, , baltic sea, , , barite, barrier reefs, , basal conglomerate, , basalt, baselevel, , basic rocks, basin deposits, bay bars, beaches, , bears, bedding planes, belemnites, belt mountains, bergschrund, , , bermudas, birds, bison, bitter root mountains, black hills, , blastoids, blastosphere, block mountains, , blowholes, blue ridge, , bomb, volcanic, bonneville, lake, , bosses, bowlders, erratic, of weathering, brachiopods, , , , , brazil, , breccia, , , british columbia, , bronze stage, , bryozoans, bunker hill, calamites, , calcareous rocks, calciferous series, calcite, caldera, california, , , , , , , , , , , , , , , , great valley of, , , , cambrian period, glaciation in, life of, camels, canada, , , , , , , , , , , , , , , , , , , cape breton island, cape cod, carbonated springs, carbonates, formation of, carboniferous period, life of, carnivores, cascade mountains, , cats, catskill mountains, caucasus mountains, caverns, , cenozoic era, centipedes, cephalopods, , , , , , ceratites, ceratosaurus, chain coral, , chalcopyrite, chalk, , , chalybeate springs, champlain subsidence, charleston earthquake, chazy series, chelan, lake, chemung series, , chesapeake bay, , , chicago, , , chile, china, , christmas island, , cincinnati anticline, , cirques, clinton series, coal, , , coal measures, coast range, , , coastal plain, atlantic, coelenterates, coke, colorado, , , , , , , , , colorado plateaus, , colorado river, , , , , , , , columbia lavas, columnar structure, concretions, cones, alluvial, volcanic, conglomerate, , congo river, conifers, connecticut, valley, contemporaneous lava sheets, , continental delta, , continental shelf, continents, contours, copper, , coquina, coral reefs, corals, ancient, , , , cordaites, cordilleran ice field, corniferous series, coves, crabs, crandall volcano, , crater lake, creodonts, cretaceous period, crinoids, , , crocodiles, cross bedding, , crustacea, , , , crustal movements, cumberland plateau, cup corals, cycads, , cycle of erosion, , , cystoids, , , dalmatia, darwin's theory of coral reefs, dead sea, , death gulch, deep-sea deposits, deer, deflation, deformation, delaware river, , deltas, , , of ganges, of indus, of mississippi, , denudation, denver, desert, , devitrification, devonian period, , dicotyls, , digitigrade, dikes, , dinosaurs, dinothere, diorite, dip, dip fault, diplodocus, dipnoans, discina, dismal swamp, dogs, dragon flies, drift, , , bowlders of, englacial, extent of, pebbles of, , stratified, thickness of, driftless area, drowned valleys, drumlins, duluth, dunes, dust falls, earth, age of, , , interior of, earthquakes, , causes of, , charleston, distribution of, geological effects of, india, japan, new madrid, earthworms, , echinoderms, , , , , edentates, egypt, electric peak, elephants, elevation, effects of, movements of, eocene epoch, epicontinental seas, erratics, , eskers, etna, , europe, pleistocene ice sheet of, eurypterids, , , , evolution, , faceted pebbles, , , falls of the ohio, fan folds, fault scarps, faults, faunas, feldspar, , , ferns, finger lakes, fire clay, fishes, , , , , fissure eruptions, fissure springs, fjords, , flint, , flood plains, , floods, floras, florida, , , , , , flow lines, fluorite, folded mountains, folds, , foliation, foraminifera, , : forests, carboniferous, , cretaceous, , devonian, tertiary, fort wayne, fossils, , fractures, fragmental rocks, france, , cave men of, fringing reefs, frogs, frost, fundy, bay of, gabbro, ganges, , , ganoids, garnet, gases, volcanic, gastropods, gastrula, geneva, lake, geodes, geological time, divisions of, geology, definition of, , departments of, georgia, , geysers, , glacial epoch, , glaciers, abrasion by, alpine, compared with rivers, , crevasses of, deposition by, greenland, lower limit of, melting of, mode of formation, moraines, motion of, , , piedmont, , plucking by, tables, transportation by, troughs, wells, young and mature, glauconite, globigerina ooze, glyptodon, gneiss, goats, gold, , goniatite, , graded slopes, granite, , graphite, graptolites, , gravitation, great basin, , , , great lakes, , great plains, great salt lake, greenland, , , green mountains, , , green sand, ground water, ground water surface, gryphæa, gymnosperms, , gypsum, , , , hade, hamilton series, hanging valley, hanging wall, hartz mountains, hawaiian volcanoes, , , , heat and cold, helderberg series, hematite, henry mountains, , high plains, , hillers mountain, himalaya mountains, , , , historical geology, , honeycomb corals, hood, mount, , hooks, hornblende, hornblende schist, hudson bay, , hudson river, , hudson series, , humus acids, humus layer, huronian systems, hwang-ho river, hydrosphere, hydrozoa, icebergs, , iceland, , ichthyosaurus, idaho, , igneous rocks, , , , , illinoian formation, illinois, , , , india, , , , , , indian territory, indiana, , indo-gangetic plain, indus river, , insects, , , interior of earth, internal geological agencies, intrusive masses, intrusive rocks, intrusive sheets, inverness earthquake, iowa, , , , , , , , , , , , iowan formation, iron ores, , , , islands, coral, wave cut, , japan, , , joints, , , jordan valley, jura mountains, , jurassic period, kame terraces, kames, kansan formation, kansas, , , , , , , , kaolin, karst, katahdin, mount, keewatin ice field, kentucky, , , , keweenawan system, , kilauea, kings river canyon, krakatoa, labrador, labrador ice field, laccolith, lagoon, , lahontan, lake, , lake chelan, lake dwellings, lake geneva, lake superior region, , , lakes, , , basins, , , , , , , , , , , , , , , , deposits, glacial, , , , , , pleistocene, salt, laminæ, landslides, , lapilli, laramie series, laurentian peneplain, , , lava, , lava domes, , lepidodendron, , lichens, lignite, limestone, , , , limonite, lingulella, lithosphere, lizards, llamas, loess, , long island, louisiana, , lower silurian period, luray cavern, lycopods, magnetite, , maine, , malaspina glacier, maldive archipelago, mammals, , , mammoth, mammoth cave, mammoth hot springs, man, , mantle of waste, marble, , marengo cavern, marl, marsupials, , martha's vineyard, , , maryland, , massachusetts, , , , , , , mastodon, , , matterhorn, maturity of land forms, mauna loa, meanders, medina series, , megatherium, mendota, lake, mesa, , , mesozoic era, mesozoic peneplain, , metamorphism, mexico, , mica, mica schist, michigan, , , michigan, lake, , mineral veins, , minnesota, , miocene series, mississippi, mississippi embayment, , , mississippi river, , , , , , mississippian series, missouri, , missouri river, , mobile bay, mohawk valley, , molluscous shell deposits, mollusks, monadnock, monkeys, monoclinal fold, monocotyls, , monotremes, , montana, , , , montreal, , monuments, moraines, mosasaurs, mountain sheep, mountains, age of, life history of, , origin of, , , sculpture of, , movements of crust, muir glacier, , nantucket, naples, narragansett bay, natural bridges, natural gas, natural levees, nautilus, nebraska, , , , , nebular hypothesis, neolithic man, , nevada, , , , , , , névé, new brunswick, new england, , , , , , , , , newfoundland, new jersey, , , , , , , , , , , new madrid earthquake, new mexico, , , new york, , , , , , , , , , , , , , niagara falls, , niagara series, nile, , , normal fault, north carolina, north dakota, north sea, notochord, nova scotia, nunatak, , ohio, , , , , ohio river, , oil, olenellus zone, olivine, oolitic limestone, ooze, deep-sea, ordovician period, , life of, oregon, , , oreodon, ores, , organisms, work of, oriskany series, ornithostoma, orthoceras, , , oscillations, a cause of, effect on drainage, ostracoderms, ottawa river, outcrop, outliers, outwash plains, oxidation, oyster, , pahoehoe lava, palæospondylus, paleolithic man, paleozoic era, palisades of hudson, palms, pamir, peat, , peccaries, pelecypods, pelée, mt., peneplain, dissected, laurentian, , , mesozoic, , pennsylvania, , , , , , pennsylvanian series, , perissodactyl, perlitic structure, permian series, , , , petrifaction, petroleum, , phenacodus, phyllite, phyllopod, piedmont belt, , , , piedmont plains, pikes peak, _pithecanthropus erectus_, placers, plains of marine abrasion, planation, plantigrade, platte river, playa, playa lakes, pleistocene epoch, plesiosaurus, , pliocene epoch, plucking, po river, , pocono sandstone, , porosity of rocks, porphyritic structure, potholes, potomac river, , , predentata, pre-kansan formation, primates, prince edward island, proboscidians, , , pteropods, pterosaurs, puget sound, pumice, pyrite, quarry water, quartz, , quartz schist, quaternary period, , quebec, rain, erosion, rain prints, recent epoch, , , reconcentration of ores, record, the geological, red clay, red river of the north, red sea, red snow, reefs, coral, regional intrusions, reptiles, , rhinoceros, rhizocarp, rhode island, rhone glacier, rhyolite, richmond, va., rift valleys, ripple marks, rivers, bars, braided channels, deltas, deposition, discharge, erosion, estuaries, flood plains, floods, graded, gradients, load of, mature, , , , meanders, plains, profile of, revived, run-off, structure of deposits, terraces, transportation, , waterfalls, young, roches moutonnées, , rock bench, hock salt, , , rocky mountains, , , ruminants, saber-tooth tiger, saguenay river, , sahara, , , st. elias range, st. peter sandstone, salamanders, salina series, salt, common, , salt lakes, san francisco bay, sand, beach, of deserts, reefs, , storms, sandstone, , , sarcoui, sauropoda, schist, schladebach, scoria, , scorpions, , , scotland, , , sea, erosion, deposition, transportation, sea arch, sea cave, sea cliff, , sea cucumber, seals, sea stacks, sea urchin, , seaweed, sedimentary rocks, , selkirk mountains, septa, sequoia, shale, , sharks, , shasta, mount, , sheep, shenandoah valley, shores of elevation, shores of depression, siderite, sierra nevada mountains, , , , , , , , , , , , , , , , sigillaria, , silica, , silurian period, , life of, sink hole, slate, , slaty cleavage, slickensides, snake river lavas, , snakes, , soil, solfatara, solution, soufriére, south america, south carolina, south dakota, , , spanish peaks, , spherulites, spiders, spitzbergen, sponges, , springs, thermal, stalactite, stalagmite, starfishes, staubbach, stegosaurus, stoss side, stratification, , , striæ, glacial, , , strike, strike fault, stromatopora, , stromboli, subsidence, , , sun cracks, superior, lake, superposition, law of, susquehanna river, sutlej river, sweden, swine, switzerland, , syenite, synclinal fold, syracuse, n.y., syringopora, tabulæ, taconic deformation, taconic mountains, talc, talc schist, talus, tapir, teleost fishes, , , tennessee, , terminal moraines, , , terraces, , tertiary period, texas, , , , , , , , , , , theromorphs, throw, thrust faults, till, till plains, toronto, trachyte, , travertine, trenton series, triassic period, triceratops, trilobites, , , , , tuff, turkestan, turtles, unconformity, undertow, utah, , , , , , utica series, v-valleys, valley drift, valley trains, valleys, vermont, , , vernagt glacier, vertebrates, , vesuvius, , , virginia, , , , , , volcanic ashes, , cones, necks, rocks, volcanoes, causes of, decadent, submarine, tertiary, walrus, warped valleys, warping, wasatch mountains, washington, , , , waterfalls, , waves, weathering, chemical, differential, mechanical, wells, artesian, west virginia, , , white mountains, wind, deposition, erosion, pebbles carved by, transportation, wisconsin, , , , , , , , wisconsin formation, , wyoming, , , yahtse river, yellow sea, , yellowstone canyon, yellowstone national park, , , , , , , , yosemite, zeuglodon, zone of cementation, , zone of solution, zones of flow and of fracture, * * * * * announcements ================================================================= text books on science for higher schools and colleges _list _mailing price_ price_ bergen's elements of botany. 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(revised edition) . . young's manual of astronomy . . ================================================================= ginn & company publishers davis' elementary physical geography ================================================================= by william morris davis _author of davis' "physical geography" and professor of geology in harvard university_ mo. cloth. viii + pages + color charts + pages of maps. illustrated. list price, $ . . the "elementary physical geography" is a new book by professor w. m. davis, the first authority in the united states in the field of physical geography. it retains the characteristic features of the author's earlier work, "physical geography," but is much less difficult and is admirably adapted for use with younger pupils. the plan of this volume, like that of its predecessor, is to give the problems of physical geography a rational treatment. the object of this method is not simply to explain physiographic facts, but to increase the appreciation of the facts themselves by associating them with their causes and their consequences. this relation is not presented merely as an afterthought in a detached chapter at the end of the book; it accompanies the presentation of the facts themselves. the chapter on the atmosphere has been considerably expanded, and an entirely new chapter has been added on the distribution of plants, animals, and man, considered from a physiographic standpoint. the questions at the end of each chapter, prepared by an experienced high-school teacher, will be found most useful in class-room work with this book. especially notable are the illustrations, which include nearly two hundred splendid woodcuts, five pages of charts in color, and nineteen full-page half-tone plates from rare photographs. * * * * * the nation, july , : taken all in all, this seems the most satisfactory elementary text-book in physical geography yet published. certainly in its treatment of the land it has not been surpassed unless, perhaps, by the author's larger work ["physical geography"]. ================================================================= ginn & company publishers ================================================================= geographic influences in american history by albert perry brigham professor of geology in colgate university. mo. cloth. pages. illustrated. list price, $ . ; mailing price, $ . * * * * * in this new book professor brigham has presented vividly and clearly those physiographic features of america which have been important in guiding the unfolding of our industrial and national life. the arrangement is mainly geographical. among the themes receiving special treatment are: the eastern gateway of the united states, the appalachian barrier, the great lakes and american commerce, the civil war, and mines and mountain life. closing chapters deal with the unity and diversity of american life and with physiography as affecting american destiny. the book will be found particularly interesting and valuable to students and teachers of geography and history, but it will also appeal to the general reader. the very large number of rare and attractive photographs and the numerous maps are of importance in vivifying and explaining the text. ================================================================= ginn & company publishers ================================================================= the best example in this country of the kind of books that geography needs.--_the nation_ the lakes of north america by israel c. russell professor of geology in the university of michigan vo. cloth, xi + pages. illustrated. list price, $ . ; mailing price, $ . recent advances have made physical geography almost a new science. professor russell here presents a single phase, but one of great importance. the work is based upon his original investigations, and is at once thoroughly scientific in substance and enjoyably popular in style. as a text-book or reading book for students in geography and geology the "lakes of north america" possesses a unique value. its interest to the general reader is enhanced by its illustrations and its happy descriptions of lake scenery. glaciers of north america by israel c. russell, professor of geology in the university of michigan author of "lakes of north america" vo. cloth. x + pages., illustrated. list price, $ . ; mailing price, $ . recent explorations have shown that north america contains thousands of glaciers, some of which are not only vastly larger than any in europe, but belong to types of ice bodies not there represented. in the study of the glaciers of north america, and especially of those in alaska, professor russell has taken an active part; and this book not only presents the results of his own explorations but also a condensed and accurate statement of the present status of glacial investigations. its popular character and numerous illustrations will make it of interest to the general reader. * * * * * _department of special publication_ ================================================================= ginn & company publishers * * * * * transcriber's notes this transcription was derived from the publication obtained from the internet archive. as the index of the original book is missing entries for u and v, the index from the version was used to add the missing sections. one error was noted in preparing this revision (page under hudson river should have been ). several hyphenated vs. unhyphenated forms were standardized to the most prevalent. minor corrections were made where periods, commas, etc. were missing. a number of paragraphs which were split by images were rejoined. in some cases, the text was moved to the preceding or following page. as all caps was employed for the chapter titles in the original book, the small caps subchapter headings and figure captions were not converted to all caps. the oe ligature in coelenterates was converted to "oe". none th congress _ d session_ house of representatives document no. department of the interior franklin k. lane, secretary united states geological survey george otis smith, director bulletin conservation through engineering by franklin k. lane extract from the annual report of the secretary of the interior [illustration] washington government printing office contents. page. the coal strike national stock-taking coal as a national asset public responsibility the miners' year have we too many mines and miners? the long view saving coal coal and coal expansion abroad saving coal by saving electricity white coal and black the age of petroleum oil shale save oil use the diesel engine wanted--a foreign supply by way of summary land development a program of progress garden homes for the people reclamation by district organization soldier-settlement legislation alaska matanuska coal save and develop americans note. the plea for constructive policies contained in the report of the secretary of the interior to the president deserves a hearing also by the engineers and business men who are developing the power resources of the country. the largest conservation for the future can come only through the wisest engineering of the present. the conditions under which the utilization of natural resources is demanded are outlined by secretary lane, and it will be noted that the program recommended calls for the cooperation of engineer and legislator. to bring this power inventory to the attention of the men who furnish the nation with its coal and oil and electricity, this extract from the administrative report of the secretary of the interior is reprinted as a bulletin of the united states geological survey. conservation through engineering[ ] by franklin k. lane. in an age of machinery the measure of a people's industrial capacity seems to be surely fixed by its motive power possibilities. civilized nations regard an adequate fuel supply as the very foundation of national prosperity--indeed, almost as the very foundation of national possibility. i am convinced that there will be a reaction against the intense industrialism of the present, but as it must be agreed that the race for industrial supremacy is on between the nations of the world, america may well take stock of her own power possibilities and concern herself more actively with their development and wisest use. the coal strike. the coal strike has brought concretely before us the disturbing fact that modern society is so involved that we live virtually by unanimous consent. let less than one-half of per cent of our population quit their work of digging coal and we are threatened with the combined horrors of pestilence and famine. it did not take many hours after it was realized that the coal miners were in earnest for the american imagination to conceive what might be the state of the country in perhaps another days. industries closed, railroads stopped, streets dark, food cut off, houses freezing, idle men by the million hungry and in the dark--this was the picture, and not a very pleasant one to contemplate. there was an immediate demand for facts. how much coal is normally mined in this country? by whom is it mined? what is its quality? to what uses is it put? who gets it? how much less could be mined if coal were conserved instead of wasted? what better methods have been developed for using coal than those of ancient custom? who is to blame that so small a supply is on the surface? why should we live from day to day in so vital a matter as a fuel supply? what substitutes can be found for coal and how quickly may these be made available? this is by no means an exhaustive category of the questions which were put to this department when the strike came. and these came tumbling in by wire, by mail, by hand, from all parts of the country, mixed with disquisitions upon the duty of government, the rights of individuals as against the rights of society, the need for strength in times of crisis, calls for nationalization of the coal industry, for the destruction of labor unions, for troops to mine coal, and much else that was more or less germane to the question before the country. many of these questions we were able to answer. but if coal operators themselves had not carried over the statistical machinery developed during the war, we would have been forced to the humiliating confession that we did not know facts which at the time were of the most vital importance. in a time of stress it is not enough to be able to say that the united states contains more than one-half of the known world supply of coal; that we, while only per cent of the world's population, produce annually per cent of all coal that is taken from the ground; that per cent of the railroad traffic is coal; that in less than years we have grown in production from , tons to , , tons per annum; that if last year's coal were used as construction material it would build a wall as huge as the great wall of china around every boundary of the united states from maine to vancouver, down the pacific to san diego and eastward following the mexican border and the coast to maine again; and that this same coal contains latent power sufficient to lift this same wall miles high in the air, according to one of our greatest engineers (steinmetz). such facts are surely startling. they serve to stimulate a certain pride and give us a great confidence in our industrial future; yet they are not as immediately important, when the mines threaten to close, as would be a few figures showing how much coal we have in stock piles and where it is! and months since we called upon congress to grant the money that we might secure these figures, but no notice was taken of the urged requests until, late in the summer, a committee of the senate awoke to this need and indorsed our petition. national stock taking. the government should have a more complete knowledge of the coal and of other foundation industries than can be found elsewhere, and we should not fear national stock taking as a continuing process. it is indeed the beginning of wisdom. the war revealed to us how delinquent in this regard we had been in the past. one day when the full story is told of the struggle of the army engineer to meet war emergency demands, and this is supplemented by the tale of the effort made by the council of national defense and the war industries board, it will be realized more seriously than now how little of stock taking we have done in this generous, optimistic land. when any such undertaking is proposed, however, it at once appears to arouse the fear that it is somehow the beginning of a malevolent policy called "conservation," and conservation has had a mean meaning to many ears. it connoted stinginess and a provincial thrift, spies in the guise of government inspectors, hateful interferences with individual enterprise and initiative, governmental haltings and cowardices, and all the constrictions of an arrogant, narrow, and academic-minded bureaucracy which can not think largely and feels no responsibility for national progress. needless to say this fear should not, need not be. the word should mean helpfulness, not hindrance--helpfulness to all who wish to use a resource and think in larger terms than that of the greatest immediate profit; hindrance only to those who are spendthrift. a conservation which results in a stalemate as between the forces of progress and governmental inertia is criminal, while a conservation that is based on the fuller, the more essential use of a resource is statesmanship. to know what we have and what we can do with it--and what we should not do with it, also!--is a policy of wisdom, a policy of lasting progress. and in furtherance of such a policy the first step is to know our resources--our national wealth in things and in their possibilities; the second step is to know their availability for immediate use; the third step is to guard them against waste either through ignorance or wantonness; and the fourth step is to prolong their life by invention and discovery. coal as a national asset. enough has been said, perhaps, to indicate how vast are the fields of coal which this country holds. it may be that any day some genius will release from nature a power that will make of little value our carboniferous deposits save for their chemical content. by the application of the sun's rays, or the use of the unceasing motion of the waves of the sea, the whole dependence of the world upon coal may be upset. that day, however, has not yet come; and until it does we may consider our coal as the surest insurance which we can have that america can meet the severest contest that any industrial rival can present. it is more than insurance--it is an asset which can bring to us the certainty of great wealth, and if we care to exercise it, a mastery over the fate and fortunes of other peoples. next to the fertility of our soil, we have no physical asset as valuable as our coal deposits. although we are sometimes alarmed because those deposits nearest to the industrial centers are rapidly declining and we can already see within this century the end of the anthracite field, if it is made to yield as much continuously as at present, yet it is a safe generalization that we have sufficient coal in the united states to last our people for centuries to come. an extra scuttleful on the fire or shovelful in the furnace does not threaten the life of the race, even if some russian or chinese of the future does not resolve the atom or harness the hidden forces of the air. whatever fears other nations may justifiably have as to their ability to continue in the vast rush of a machine world, there can be no question of our ability to last. the present strike, however, makes quite clear, perhaps for the first time, that it is not the coal in the mountain that is of value, but that which is in the yard. and between the two there may be a great gulf fixed. therefore, we are put to it to make the best of what we have. we turn from telling how much coal we use to a study of how little we can live upon and do the day's work of the nation. and this is, i believe, as it should be. indeed i feel justified in saying that the problem of this strike is not to be solved in its deeper significances until we know much more about coal than we know now, and this especially as to the manner in which it is taken from its bed and brought to our cellars. public responsibility. this transfer is effected by a kind of carrier chain, the links of which are the operator, the miner, the railroad, and the public. we choose, to please ourselves, the link in this chain upon which we place the responsibility for its failure to work; but before indulging ourselves in abuse of arrogant coal barons or dictatorial labor unions, it may lie as well to ask whether we of the public are not responsible in some part for this failure to function. i do not refer now to the failure of society to provide methods of industrial mediation or other adjustment of such labor difficulties. my question is, whether or not the public is at all at fault when a nation wealthy beyond all others in coal finds itself with so small a supply on hand when a strike comes--but a few days removed from the gravest troubles. the answer, to my mind, turns upon the manner in which we have done business. we have been content to go without insurance as to a coal reserve. each day has brought its daily supply. there was no thought of railroads stopping or mines closing down, so that large storage facilities have not been provided, and, indeed, we would rebel at paying for our coal the added cost of caring for it outside its native warehouse. we have not thought in terms of apprehension, but, as always, in the calm certainty that the stream of supply would flow without ceasing. in some way there would be coal into which we could drive our shovels when the need was felt. no wonder, therefore, that we are rudely disturbed when one link in the carrier chain from coal-in-place to coal-in-the-furnace breaks. it simply is one of those things which doesn't happen. and not having happened sufficiently often to give us fear, we have had no thought that we should provide against it. it is a most heterodox thing to say, but we may find that a bit more foresight on the part of the public would certainly have made less sudden the present crisis. let us look, for instance, into the matter of the coal miners' year and see if it is not fixed in some degree by the habit of the public in its purchasing. the miners' year. the record year, , with everything to stimulate production had an average of only working days for the bituminous mines of the country. this average of the country included a minimum among the principal coal-producing states of days for arkansas and a maximum of for new mexico. in such a state as ohio the average working year is under days. in the miners of new mexico reached an average of days, and in the largest field, the raton field, it was actually --probably the record for steady operation. this short year in coal-mine operation is due in part to seasonal fluctuation in demand. the mines averaged only hours a week during the spring months. the weekly report of that date showed that per cent of the lost time was due to "no market" and only per cent to "labor shortage," while "car shortage" was a negligible factor. in contrast with this should be taken the last week before the strike, when the average hours operated were and "no market" was a negligible item in lost time, while "car shortage" was by far the largest item. it follows that the short year is a source of loss to both operator and mine worker and is a tax on the consumer.[ ] with substantially the same number of mines and miners working this year as last, the accumulative production for the first months of this year is , , tons less than that mined in the same period last year. this per cent loss in output means that both plant and labor have been less productive, and, in terms of capital and labor, coal cost the nation more this year than last. for in the long run both capital and labor require a living wage. the public must accept responsibility for the coal industry and pay for carrying it on the year round. mine operators and mine workers of whatever mines are necessary to meet the needs of the country must be paid for a year's work. the shorter the working year the less coal is mined per man and per dollar invested in plant, and eventually the higher priced must be the coal. it is obvious that the short tons of coal mined by the average british miner last year could not be as cheap per ton as the tons mined by the average american mine worker, backed up as he was with more efficient plant. (a proud contrast!) it would clearly appear that the coal business may be stabilized, not wholly, but in a very large measure, in some of the western fields,[ ] if the public does not regard its supply of coal as it does its supply of domestic water, which requires only that the faucet shall be opened to bring forth a gushing supply. coal does not have pressure behind it which forces it out of the mine and into the coal yard. it rather must be drawn out by the suction of demand. and herein the public must play its part by keeping that demand as steady and uniform as possible. have we too many mines and miners? the problem of the miner and his industry may be stated in another way. we consume all the coal we produce. we produce it with labor that upon social and economic grounds works as a rule too few days in the year. we therefore must have a longer miners' year and fewer miners or a longer miners' year and additional markets. one or the other is inevitable unless we are to carry on the industry as a whole as an emergency industry, holding men ready for work when they are not needed in order that they may be ready for duty when the need arises. there are too many mines to keep all the miners employed all of the time or to give them a reasonable year's work. this conclusion is based on the assumption that we now produce only enough coal from all the mines to meet the country's demand, which is the fact. more coal produced would not sell more coal, but more coal demanded would result in greater coal production. with the full demand met by men working two-thirds or less of the time in the year there can not be a longer year given to all the miners without more demand for coal. this seems to be manifest. therefore the miners must remain working but part time as now, or fewer miners must work more days, or market must be found for more coal and thus all the miners given a longer year. if we worked all of our miners in all of our mines a reasonable year, we would have a great overproduction. and to have all our mines work a longer period means that we must find some place in which to sell more coal, either at home or abroad. why have we so many mines working so many miners? there can be no one-word reply to this question. it penetrates into almost every social and economic condition of the country--the initiative of capital, the size of the country, the pride of localities, the intense competition between railroads, their inability to furnish cars when needed, the manner in which cars are apportioned between mines, the manner in which the railroads are operated so that movement is slow and equipment is short, and this runs into the need for new facilities, such as more yards, more tracks, more equipment, which brings us into the need for more capital and so on and on. we have none too many mines or too many miners to supply our need if the mines are operated as at present. but we have too many to fill that need if they are operated on a basis nearer to per cent of possible production. the long view. passing from the labor phase of the coal situation to the larger aspect of our coal supply as related to the whole problem of the economical production of light, heat, and power, which sir william crookes has characterized as "first among the immediate practical problems of science," we find ourselves both rich and wasteful, following the primrose path, heedless of the morrow and not yet conscious that the morrow is to be a day of battle. in the first place we treat coal as if it were a thing which was exclusively for home use, a nonexportable commodity which must be used "on the farm," whereas it should be treated with profound respect, because we know from paris that sacred treaties and national boundaries turn on its presence. the world wants our coal, envies us for having it, fears us because of it. it is not only useful to us, but it has a cash value in the markets of the world. therefore it should be saved. in the next place we treat coal as if it were all alike, not selected by nature for specific uses; whereas we should choose our coal with as scientific a judgment as we choose our reading glasses. there is coal for coke and coal for furnaces and coal for house use and coal adapted for one kind of boiler and a different kind of coal for a different kind of boiler. therefore we should discriminate in coal. and again we have shown little willingness to dignify coal by seeking to draw out by improved mechanical processes all the stored content of heat in this lump of carbon. instead we content ourselves by giving it a mere pauper touch, driving off the greater volume of its value into the air. this is a task for the mechanical engineer. then, too there is the problem of using coal in the form of steam or in the more exalted form of electric current. the lifting, bobbing lid of james watt's teakettle did not speak the last word in power. we are only beginning to know how we may move on from one form of motive power to another. the wastefulness of steam power as contrasted with electric power is a real challenging problem in conservation by itself. and then we naturally ask, why this long haul over mountains and through tunnels and across bridges and along streets and into houses, by railroad, truck, and on the backs of men, when at the very pit mouth, or within the mine itself, this same coal might be transformed into electricity and by wire served into factories and homes , , miles from the mine? why burden our congested railroads with this traffic? why strew our streets with this dirt? this may be a practicable thing, a wise thing; it deserves study if coal is worth conserving. are there no substitutes for coal which we can use and can not export? this question immediately raises the water-power possibilities of our land, of which only the most superficial study has been made. sell coal and use electricity would appear a thrifty policy. as petroleum is being used as a substitute for coal--and inasmuch as the whole problem of fuel supply is one--we are ultimately compelled to an investigation of the ability of our petroleum supply to meet its present drain and to meet the expansion in its use, which is the most surprising development of our day in the study of power creation. this spells a program of development and conservation which should challenge the ambitions of this nation, and on a few of its features perhaps a few further words would be justified. saving coal. the two ways by which coal in greatest volume can be saved are the discovery of the method by which more power can be taken from the ton and the discovery of what kind of coal is best fitted for any particular use. it has been everyone's business to save coal, hence.... the railroads have experimented with some success. they get perhaps per cent of the heat energy from a ton shoveled beneath the locomotive boiler, per cent of the total in the ton. they use one-quarter of all the coal mined. next to labor this is the greatest expense which our railroads have. this shows how great the problem is to them. some have adopted a system of paying a bonus for the greatest distance made on a given quantity of a given coal. but this laudable effort has not met with the cooperation that would be expected from the firemen, for reasons that go far afield. industries, especially those which generate electric power, have made similar effort to gain from their fuel its greatest potentiality, and with varying success. we can overlook the stoking of the domestic furnace as a national concern, for the amount of coal used in this way amounts to not more than per cent of the national coal bill, and this whole charge could be saved, it is estimated, by giving care to the per cent of our coal which is burned under boilers to make steam. here there is a maximum figure of per cent of the energy of the coal put into harness, and the average is less than per cent, even in the larger plants. in one establishment visited by the fuel engineers of this department during the war a preventable waste of , tons a year was discovered. by changes in the admission of air to the furnaces and in the "baffling" of the boilers the engineers of the bureau of mines are confident that they have been able to increase the economy of coal in the ships of the emergency fleet corporation by per cent, making pounds of coal do the work of . if such a percentage of economy could be generally effected it would mean the saving of as much coal as france and italy together will need in this year of their greatest distress. coal and coal. the government should sample and certify coal. we do this as to wheat and meat; it is just as necessary to avoid injustice in the case of coal, and it is thoroughly practicable. the public should know the kind of coal it is buying, because it should buy the coal it needs. there need be no prohibition against the mining or selling of any coal,[ ] but coal should sell in terms of its capacity to deliver heat. some coal that is only a pint bottle is selling as a quart bottle. and the quart is hurt by the competition of the pint. a bill to effect such fuel inspection has been drafted and will be presented to congress. it is not a bill commanding anything, but rather gives to those who are willing an opportunity to have their product inspected and attested and thus acquire merit in the eye of the world as against those who are not willing to subject their coal to the official test tube. coal is coal in the sense of the classic traffic classification. coal is, however, not always coal, nor is it altogether coal when put to the pragmatic test of the furnace. if such a bill were passed it would promote the interests of those who schedule their price upon the merit of their goods and make against the hauling of slate and dirt, its storage and handling under an assumed name. the plan is not to punish the malefactor who attempts to impose upon the public a slender number of thermal units as a ton of coal, but rather to give to ever man an opportunity to advertise the number of such units which his particular article contains, thus enabling the injured public to strike against an unfair mine. furthermore we are to become great exporters of coal, unless all signs fail, and such certification should be required as to every ton sent abroad. expansion abroad. it has been said that we have too many mines in operation, as we appear to have too many miners, if we are to maintain only our present output. rapid expansion in the development of industry in general may justify the existence of such mines and so large a corps of workers, even with an adequate car supply and more abundant local storage facilities, which are greatly needed in almost all places, and a more even demand. if, however, this should not be so, there is a foreign demand for the best of our bituminous coals, which at present we are altogether unable to meet for lack of credits on the part of those who wish the coal, and lack of ships to carry it. england's annual production has fallen , , tons, according to mr. hoover, and the european demand next year will be more than , , tons above her production. whatever the world need, it can not be supplied. it is too large for any possible supply by ship, even if all necessary financial arrangements could be made, either by loan or credit. europe, indeed, will sadly learn through this winter how little coal she can live on and how more than perilous is the state of a people who are short of power, light, and heat. as this country prior to the war sold abroad no more than , , tons as against england's , , , it is quite manifest that here will be a new field for american enterprise, the enterprise being needed not for the winning of markets as much as for finding ways of dealing with the larger phases of a heavy overseas trade with those who are without immediate resources. saving coal by saving electricity. it is three years since congress was urged that we should be empowered to make a study of the power possibilities of the congested industrial part of the atlantic seaboard, with a view to developing not only the fact that there could be effected a great saving in power and a much larger actual use secured out of that now produced, but also that new supplies could be obtained both from running water and from the conversion of coal at the mines instead of after a long rail haul. a stream of power paralleling the atlantic from richmond to boston, a main channel into which run many minor feeding streams and from which diverge an infinite number of small delivering lines--the whole an interlocking system that would take from the coal mine and the railroad a part of their present burden and insure the operation of street lights, street cars, elevators, and essential industries in the face of railroad delinquencies--this is the dream of our engineers, and a very possible dream it has seemed to me; of such value, indeed, that we might well spend a few thousand dollars in studying it, not with the thought that the government would construct or operate even the trunk line, but that it might so attract the attention of the engineering and financial world as to make it a reality. to tie together the separated power plants of states so that one can give aid to the other, so that one can take the place of the other, so that all may join their power for good in any great drive that may be projected--this would be the prime purpose of the plan; and from this would evolve the development of the most practicable method of supplying this vast interdependent system with more power--perhaps from the conversion of coal, as it drops from the very tipple, using the mine as one might use a waterfall, or by the development of great hydroelectric plants on the many streams from the androscoggin to the james. white coal and black. this would be a plan for the wedding of the stream and the mine, the white coal with the black. "white coal" they call it in imaginative france, this tumbling water which is converted into so many forms; and a much cleaner, handier kind of coal it is than its black brother. and cheaper, for the water goes on to return again and fall once more and forever into the pockets of the turbine which whirls the dynamo and so gathers or releases that mystery which we name but never define. farsighted, purposeful germany fought four and a half years upon the strength of great power plants run by the snows of the alps. she did not rely on these alone for power, nor were they her main reliance, but they gave her a lasting power which otherwise she would not have had. and we may expect her to improve on that war-time experience for the conduct of the hard fight she is to make in the industrial field. france saved enough territory from the invader to permit her to make new adventures into this field and so to some degree offset the coal loss of lens. italy found that she had still left unused opportunities for hydroelectric development sufficient with the coal she could secure from england and america to see her through the war. and with coal conditions as they are in europe we may expect a still greater push to make use of water power to turn the industrial wheels of peace. it must be so likewise here. and it is likely that the long-pending power bill which will make available the dam and reservoir sites on withdrawn public lands and make feasible the financing of many projects on both navigable and unnavigable streams will soon have become law. we shall then have an opportunity that never before has been given us to develop the hydroelectric possibilities of the country. and this raises the question as to their extent. the theoretical maximum quantity of hydroelectric power that can be produced in the united states has recently been estimated by dr. steinmetz, who calculates that if every stream could be fully utilized throughout its length at all seasons, the power obtained would be , , kilowatts ( , , horsepower). it is clear that only a fraction of this absolute maximum can ever be made available. the geological survey estimates that the water power in this country that is available for ultimate development amounts to , , continuous horsepower. the census of showed that the country's developed water power was , , horsepower, about per cent of the maximum power available for economic development and less than per cent of the total that may be supplied by the streams as estimated by dr. steinmetz. according to the census, stationary prime movers representing a capacity of more than , , horsepower, furnished by water, steam, and gas, were in operation in the united states in . (this amount does not, of course, include power generated by locomotives, marine engines, automobiles, and similar mobile apparatus.) the average power furnished by these stationary prime movers was probably not more than per cent of their installed capacity, so that the power produced in was equivalent to probably not more than , , continuous horsepower. as the estimated available water power given above represents continuous power the country evidently possesses much more water power than it now requires, so that there would be an ample surplus for many years if the power were so distributed geographically that it could be economically supplied to the industries that need it. but as a matter of fact the water-power resources of the country are by no means evenly distributed. over per cent of the available water power is west of the mississippi, whereas over per cent of the total horsepower now installed in prime movers is east of the river. therefore unless the east is to lose its industrial supremacy it must press and press hard for the development of all water-power possibilities! the age of petroleum. for a full century now we have been passing through different phases of industrial and commercial life which have been characterized by some form of power. first the age of steam, and then the age of electricity. we have passed out of neither and yet we have come into another age--that of petroleum. as a lubricant, it has become of such universal use that it has been called the barometer of industry, and no doubt after it has ceased to be a popular illuminant or a source of power it will live invaluable as the thing which lets the wheels go round. its greatest popularity now arises out of its use in the internal-combustion engine, and of the making of these there is no end. it draws railroad trains and drives street cars. it pumps water, lifts heavy loads, has taken the place of millions of horses, and in years has become a farming, industrial, business, and social necessity. the naval and the merchant ships of this country and of england are fitted and being fitted to use it either under steam boilers as fuel or directly in the diesel engine. the airplane has been made possible by it. it propels that modern juggernaut, the tank. in the air it has no rival, while on land and sea it threatens the supremacy of its rivals whenever it appears. there has been no such magician since the day of aladdin as this drop of mineral oil. medicines and dyes and high explosives are distilled from it. no one knows whence it cometh or whither it goeth. men search for it with the passion of the early argonauts, and the promise now is that nations will yet fight to gain the fitful bed in which it lies. in persia and in palestine, in java and in china, in southern russia and in rumania we know that petroleum is, for it has been found there. how great these fields or others in europe, asia, or africa may be no one would dare to say. as yet, however, the petroleum of the world has come from this hemisphere. the "oil spring" which george washington found in western virginia and by his last will called to the especial consideration of his trustees was the promise of a continental well which last year yielded , , barrels. each year has seen the prophecy unfulfilled that the peak of the possible yield had been reached. from the mountains of western pennsylvania into the very ocean bed of the pacific and even beyond and into the broken strata of upturned alaska, the oil prospector bored with his sharp tooth of steel and found oil. hardly has one field fallen into a decline when another has come rushing into service. only three years ago and all hopes were centered in oklahoma, and then came kansas, and then the turn went south again to texas, and now it looks toward louisiana. geologists have estimated and estimated, and they do not differ widely, for few give more than thirty years of life to the petroleum sands of this country if the present yield is insisted upon. and yet there is so much of mystery in the hiding of this strange subterranean liquid that honest men will not say but that it will become a permanent factor in the world of light, heat, and power. if this is not so we are a fatuous people, for with every fifth man in the country the owner of an automobile and the expenditure of hundreds of millions of dollars for roads fit only for their use, and with ships by the hundred specially constructed to burn oil, we have surely given a large fortune in pledge of our faith that our pools of petroleum will not soon be drained dry, or that others elsewhere will come to our help. in the country's production of oil was , , barrels, and there was a surplus above consumption of more than , , barrels available to go into storage. in , years later, the oil wells of the united states yielded , , barrels--nearly twice the yield of --but to meet the demands of the increased consumption more than , , barrels had to be drawn from storage. the annual fuel-oil consumption of the railroads alone has increased from - / to - / million barrels; the annual gasoline production from , , gallons in to , , , gallons in . this reference to the record of the past may be taken not only as justifying the earlier appeal for federal action, but as warranting deliberate attention to the oil problem of to-day. fuel oil, gasoline, lubricating oil--for these three essentials are there no practical substitutes or other adequate sources? the obvious answer is in terms of cost; the real answer is in terms of man power. whether on land or sea, fuel oil is preferred to coal because it requires fewer firemen, and back of that, in the man power required in its mining, preparation, and transportation the advantage on the side of oil is even greater. so, too, the substitute for gasoline in internal-combustion engines, whether alcohol or benzol, means higher cost and larger expenditure of labor in its production. there are large bodies of public land now withdrawn, which, under the new leasing bill which seems so near to final passage after seven years of struggle and baffled hope, will in all likelihood make a further rich contribution to the american supply. oil shale. and beyond these in point of time lie the vast deposits of oil shale which by a comparatively cheap refining process can be made to yield vastly more oil than has yet been found in pools or sands. the value of this oil shale will depend upon the cheapness of its reduction, and this must be greatly lessened by the value of by-products before it can compete with coal or the oil from wells. there is every reason to believe, however, that some day the production of oil from shale will be a great and a permanent industry. and the country could make no better immediate investment than to give a large appropriation for the development of an economical shale-reducing plant. so conservative an authority as the geological survey estimates that the oil shales of the western states alone contain many times over the quantity of oil that will be recovered from our oil wells. the retorting of oil from oil shale has been a commercial industry for many years in scotland and france; in fact, oil was obtained from oil shale here in the united states before the first oil well was drilled. the industry is in process of redevelopment to-day and if successful will assure us of a future supply, but at the best it will take years of time and a vast investment of capital to build up the industry to such a point that it can supply any considerable proportion of our needs. it is imperative, however, that the development of this latent resource be furthered and brought to a state of commercial development as soon as possible. save oil. yet with all the optimism that can be justified i would urge a policy of saving as to petroleum that should be rigid in the extreme. if we are to long enjoy the benefits of a petroleum age, which we must frankly admit fits into the comfort-loving and the speed-loving side of the american nature, we must save this oil. we must save it before it leaves the well; keep it from being lost; keep it from being flooded out, driven away by water. through the cementing of wells in the cushing field, oklahoma, the daily volume of water lifted from the wells was decreased from , barrels to barrels, while the daily volume of oil produced was increased from barrels to , . these instances show what can and should be done in our known oil fields. we must save the oil after it leaves the well, save it from draining off and sinking into the soil, save it from leaking away at pipe joinings, save it from the wastes of imperfect storage. then we come to the refining of the oil. how welcome now would be the knowledge that we could recover what was thrown away when kerosene was petroleum's one great fraction. (the loss in refineries is still startling, some , , barrels last year-- - / per cent of the crude run in the refineries.) the self-interest of the american refiner, notably the standard oil co., has done a work that probably no mere scientific or noncommercial impulse could have equaled, in torturing out of petroleum the secrets of its inmost nature. and yet the thought will not altogether give place that in that residue which goes to the making of roads or to be burned in some crude way there may be things chemical that will work largely for man's betterment. this is the fact, too--that where the oil is produced by some small companies which have not the financial ability to make it yield its full riches there is a greater danger of loss of this kind. it would be well indeed if there could be such regulation as would require that all petroleum must be refined. that this is done generally is not denied. it should be universal. and all the skill and study and knowledge of the ablest of chemists and mechanicians should find themselves challenged by the problem of petroleum. coming to the use of petroleum in its various forms we find a field of promise. the engine that doubles the number of miles that can be made on a gallon of gasoline doubles our supply. there is where we can apply the principle of true conservation--find how little you need; use what you must, but treat your resource with respect. has the last word been said as to the carburetor? mechanical engineers do not think so. have all possible mixtures which will save oil and substitute cheaper and less rare combustibles therefor been tried? men by the hundred are making these experiments, and almost daily the quack or the stock promoter comes forward with the announcement of a discovery which proves to be a revelation--a revelation of human stupidity or criminal cupidity. on this line the men of science do not sing a song of the richest hope; they shrug their shoulders, exclaiming with uplifted hands: "well, may be, may be." there are possible substitutes for some petroleum products, but not for the whole barrel of oil; furthermore, petroleum is the cheapest material, speaking quantitatively, from which liquid fuels and lubricants can be made; therefore, any substitutes obtained in quantity must cost more. alcohol can be substituted for gasoline, but only in limited quantity and at increased cost. benzol from byproduct coking ovens also can be used, but quantitatively is totally inadequate. for kerosene no quantitative substitute is known. lubricants can be obtained from animal and vegetable fats, but mostly are inferior in quality, and there seems no hope of obtaining them in quantity. fuel oil can be largely supplanted by coal, but for the internal-combustion engine there is no quantitative substitute. use the diesel engine. we have ventured on a great shipbuilding program. our people are to once again respond to the call of the sea. on private ways and on government ways ships are being built to go round the world--ships that are to burn oil under boilers and produce steam. i presume that there is a justification for this policy, perhaps one that is as good, if not better, than can be made for the railroads of the west pursuing the same policy. i submit, however, that there should be justification shown for the construction of any oil-burning ship which does not use an engine of the diesel type. to burn oil under a boiler and convert it into steam releases but per cent of the thermal units in the oil, whereas if this same fuel oil were used directly in a diesel engine, to per cent of the power in the oil would be secured. substitute the internal-combustion engine for the steam boiler and we multiply by three or three and one-half the supply of fuel oil in the united states. instead of our fuel-oil supply being, let us say, , , barrels, it would at once rise to , , barrels or , , . i recognize that this is an impractical and unrealizable hope as applied to things as they are, but there is no reason why this should not be a very definite policy as to things that are to be. this government might itself well undertake to develop an engine of this type for use on its ships, tractors, and trucks. we simply can not afford to preach economy in oil when we do not promote by every means the use of the internal-combustion engine for its consumption. no other one thing that can be done by the government, our industries, or the people will save as much oil from being wasted and thereby multiply the real production of the united states. if such engines are delicate of handling and need specially trained engineers, which appears to be the fact, there should be little difficulty experienced in training men for such work. a nation that could educate , automobile mechanics in days might indeed develop , diesel engineers in a year. the matter is of too great moment for delay. it touches the interest of everyone. we are in the petroleum age, and how long it will last depends upon our own foresight, inventiveness, and wisdom. wanted--a foreign supply. already we are importers of petroleum. we are to be larger importers year by year if we continue--and we will--to invent and build machines which will rely upon oil or its derivatives as fuel. our business methods have been and doubtless will continue to be developed along lines that make a continuing oil supply a necessity. some of that oil must come from abroad, as nearly , , barrels did last year, and for that we must compete with the world. for while we are the discoverers of oil and of the methods of securing it and refining it, piping it, and using it, our pioneering is but a service unto the world. this situation calls for a policy prompt, determined, and looking many years ahead. for the american navy and the american merchant marine and american trade abroad must depend to some extent upon our being able to secure, not merely for to-day but for to-morrow as well, an equal opportunity with other nations to gain a petroleum supply from the fields of the world. we are now in the world and of it in every possible sense, otherwise our navy and our merchant fleet would have no excuse. no one needs to justify them--they are the expression of an ambition that carries no danger to any people. for their support we can ask no preference, but in their maintenance we can insist that they shall not be discriminated against. sometime since i presented to a board of geologists, engineers, and economists in this department this question: if in the next five years there should develop a new demand for petroleum over and above that now existing, which would amount to , , barrels a year, where could such a supply be found, and what policy should be adopted to secure it? the conclusions of this board may be summarized as follows: ( ) such an oil need could not be met from domestic sources of supply. ( ) it could not be assured unless equal opportunities were given our nationals for commercial development of foreign oils. ( ) assurance of this oil supply therefore inevitably entails political as well as commercial competition with other nationals, as other nationals controlling foreign sources of supply have adopted policies that discriminate against, hinder, and even prevent our nationals entering foreign fields. ( ) the encouragement of and effective assistance to our nationals in developing foreign fields is essential to securing the oil needed. ( ) commercial control by our nationals over large foreign sources of supply will be essential if the estimated requirements are to be assured. ( ) it is necessary that all countries be induced to abandon or adequately modify present discriminatory policies and that the interest of our nationals be protected. ( ) some form of world-wide oil-producing, purchasing, and marketing agency fostered by this government seems essential to assure the commercial control over sufficient resources to meet the competition of other nationals. england has apparently adopted such a policy. this board proposed the following program of action: ( ) to secure the removal of all discriminations to the end that our nationals may enjoy in other countries all the privileges now enjoyed by other nationals in ours: (_a_) by appropriate diplomatic and trade measures. (_b_) by securing equal rights to our nationals in countries newly organized as mandatories. ( ) to encourage our nationals to acquire, develop, and market oil in foreign countries: (_a_) by assured adequate protection of our citizens engaged in securing and developing foreign oil fields. (_b_) by promotion of syndication of our nationals engaged in foreign business, in order to effectually conduct oil development and distribution of petroleum and its products abroad. ( ) governmental action--through special agency or board: (_a_) through the organization of a subsidiary governmental corporation with power to produce, purchase, refine, transport, store, and market oil and oil products. (_b_) through the formation of a permanent petroleum administration. ( ) to assure to our nationals the exclusive opportunity to explore, develop, and market the oil resources of the philippine islands, provided discriminatory policies of other nations against our nationals are not abandoned or satisfactorily modified. i have given much thought during the past year to this problem of adding to our petroleum supply, and it has seemed to me but fair that we should first make every effort to increase the domestic supply through the methods that have been indicated-- ( ) the saving of that which is now wasted, below ground and above ground. ( ) the more intensive use, through new machinery and devices, of the supply which we have. ( ) the development of oil fields on our withdrawn territory and in new areas such as the philippines. in addition, we must look abroad for a supplemental supply, and this may be secured through american enterprise if we do these things: ( ) assure american capital that if it goes into a foreign country and secures the right to drill for oil on a legal and fair basis (all of which must be shown to the state department) it will be protected against confiscation or discrimination. this should be a known, published policy. ( ) require every american corporation producing oil in a foreign country to take out a federal charter for such enterprise under which whatever oil it produces should be subject to a preferential right on the part of this government to take all of its supply or a percentage thereof at any time on payment of the market price. ( ) sell no oil to a vessel carrying a charter from any foreign government either at an american port or at any american bunker when that government does not sell oil at a nondiscriminatory price to our vessels at its bunkers or ports. the oil industry is more distinctively american than any other of the great basic industries. it has been the creation of no one class or group but of many men of many kinds--the hardy, keen-eyed prospector with a "nose for oil" who spent his months upon the deserts and in the mountains searching for seepages and tracing them to their source; the rough and two-fisted driller, a man generally of unusual physical strength, who handled the great tools of his trade; the venturesome "wildcatter," part prospector, part promoter, part operator, the "marine" of the industry, "soldier and sailor too"; the geologist who through his study of the anatomy of the earth crust could map the pools and sands almost as if he saw them; the inventor; the chemist with still and furnace; the genius who found that oil would run in a pipe--these and many more, in most of the sciences and in nearly all of the crafts, have created this american industry. if they are permitted they will reveal the world supply of oil. and upon that supply the industries of our country will come to be increasingly dependent year by year. by way of summary. it would seem to be our plain duty to discover how little oil we need to use. to do this we must dignify coal by grading it in terms not merely of convenience as to size, but in terms of service as to its power. we should save it, if for no better reason than that we may sell it to a coal-hungry world. we should develop water power as an inexhaustible substitute for coal and if necessary compel the coordination of all power plants which serve a common territory. new petroleum supplies have become a national necessity, so quickly have we adapted ourselves to this new fuel and so extravagantly have we given ourselves over to its adaptability. to save that we may use abundantly, to develop that we may never be weak, to bring together into greater effectiveness all power possibilities--these would seem to be national duties, dictated by a large self-interest. i have gone only sufficiently far into this whole question to realize that it is as fundamental and of as deep public concern as the railroad question and that it is even more complex. no one, so far as i can learn, has mastered all of its various phases; in fact, there are few who know even one sector of the great battle front of power. a foch is needed, one in whom would center a knowledge of all the activities and the inactivities of these three great industries, which in reality are but a single industry. we should know more than we do, far more about the ways and means by which our unequaled wealth in all three divisions can be used and made interdependent, and the moral and the legal strength of the nation should be behind a studied, fact-based, long-viewed plan to make america the home of the cheapest and the most abundant and the most immediately and intimately serviceable power supply in the world. if we do this, we can release labor and lighten nearly every task. we will not need to send the call to other countries for men, and we can distribute our industries in parts of the country where labor is less abundant and where homes will take the place of tenements. one could expand upon the benefits that would come to this land if a rounded program such as has been but skeletonized here could be carried out. i am convinced that within a generation it will be effected, because it will be necessary. the simple steps now obviously needed are to pass those primary bills which are already before congress or are here suggested. but beyond this there is imperative need that some one man (an assistant secretary in this department would serve)--some one man with a competent staff and commanding all the resources of this and other departments of the government shall be given the task of taking a world view as well as a national view of this whole involved and growing problem, that he may recommend policies and induce activities and promote cooperative relationships which will effect the most economical production of light, heat, and power, which is more than the first among the immediate practical problems of science, as sir william crookes said, for it is foremost among the immediate practical problems of national and international statesmanship. land development. i wish now to ask consideration for another matter of home concern to which i gave attention in my last report and as to which the intervening year has strengthened and perhaps broadened my ideas--the development of our unused lands. it was never more vital to the welfare of our people that a creative and out-reaching plan of developing and utilizing our natural resources should go bravely forward than it is to-day. ours is a growing country, and as its social and industrial superstructure expands its agricultural foundation must be broadened in proportion. the normal growth of the united states now requires an addition of , , acres to its cultivable area each year, which means an average increase of , acres a day. fortunately, the opportunity for this essential expansion exists not only in the west, where much of the public domain is yet unoccupied, but in every part of the republic. we have a great fund of natural resources in the very oldest states, from maine to louisiana, which invite and would richly reward the constructive genius of the nation. it is claimed by those who have specialized for years on the subject of reclamation that the control and utilization of flood waters now wasted would produce within the next years more wealth than the entire cost to the united states of the war with germany. after every other war in our history the work of internal development has gone forward by leaps and bounds, and our people have thus quickly made good the economic wastes of the conflict. the needs of to-day are different from those of the past and require different treatment, but they are by no means beyond the reach of enlightened thought and action. more than a year ago we began an earnest discussion of reconstruction policies, particularly with respect to the land. but nothing has been done. not one line of legislation, not one dollar of money has been provided except in the way of preliminary investigation. we stand voiceless in the presence of opportunity and idle in the face of urgent national need. a program of progress. the great work of material development accomplished in the past has been done very largely by private capital and enterprise. doubtless this must be the chief reliance for progress in the future. we should realize, however, that this method has involved losses as well as gains, for the nation has sometimes been too prodigal in offering its natural resources as an inducement to private effort. not only so, but with the exhaustion of the free public lands in our great central valleys--the most remarkable natural heritage that ever fell into the lap of a young nation--conditions of home making and settlement have radically changed. there can be do doubt that there is an important sphere of action which the government must occupy if we are to go steadily forward with the work of continental conquest, and all it implies to the future of the nation, but in suggesting practicable steps of progress at this time i do not forget the burden of taxation which confronts our people nor the delicate and difficult task which congress is called upon to perform in trying to keep the national outgo within the national income. hence, i am now suggesting such constructive things as the government may be able to do through the exercise of its powers of supervision and direction and with the smallest possible outlay of money. under this head i put, first, the matter of suburban homes for wage earners; second, reclamation of desert, overflow, and cut-over areas, together with improvement of abandoned farms, under a system of district organization which may be made to finance itself; third, cooperation with various states in the work of internal development. garden homes for the people. there is no more baffling problem than that presented by the continued growth of great cities, but it is a problem with which we must sometime deal. it bears directly on the high cost of living and is, indeed, largely responsible for it. rent is based on land values. land values rise with increasing population. the price of food is closely related to the growing disproportion between consumers and producers, resulting from urban congestion. here is washington, a city of some , people, doubtless destined steadily to grow until--a member of congress predicts--it may touch , , twenty years hence. already the housing problem is acute, as it is in almost every other large american city. it would be a pitiful thing if the provision of more housing facilities to meet the needs of growing population meant merely more congestion and higher rents, with an ever-decreasing degree of landed proprietorship and true individual independence. such conditions, it seems to me, undermine the american hearthstone and carry a deep menace to the future of our institutions. i believe there must be a better way, and that the time has come when we should make an earnest effort to find it. within a -mile circle drawn around the capitol dome are thousands of acres of good agricultural land, of which the merest fraction has been reduced to intensive cultivation. much of it is wastefully used, and much of it is not used at all. conditions of soil, climate, and water supply are good and represent a fair average for the united states. suburban transportation is a serious problem in some localities and less so in others, but tends to become more simple with the extension of good roads and increasing use of motor vehicles, including the auto bus. somewhere and sometime, it seems to me, a new system must be devised to disperse the people of great cities on the vacant lands surrounding them, to give the masses a real hold upon the soil, and to replace the apartment house with the home in a garden. such a system should enable the ambitious and thrifty family not only to save the entire cost of rent, but possibly half the cost of food, while at the same time enhancing its standard of living socially and spiritually, as well as economically. it has been suggested that there is no better place to demonstrate a new form of suburban life than here at the national capital, where we may freely draw upon all the resources of the governmental departments for expert knowledge and advice and where the demonstration can readily command wide publicity and come under the observation of the nation's lawmakers. and i am expecting that this experiment will be made. such a plan of town or community life, rather than city life, should be extended to every other large city in the nation. a simple act of legislation, accompanied by a moderate appropriation for organization and educational work, would enable the department to put its facilities at the service of local communities and of the industries throughout the united states. this form of national leadership would be of value both to investors in the local securities and to the home builders themselves. if the work of land acquisition and construction, together with the organization of community settlements resulting therefrom, were conducted under the supervision of the state or the federal government it would safeguard the character of the movement from every point of view. therefore, i put first among the constructive things which may be done by the exercise of the government's power of supervision and direction, with the smallest outlay of money, this matter of providing suburban homes for our millions of wage earners. reclamation by district organization. the provision of garden homes for millions of city workers will contribute largely to the nation's food supply and become in time a most effective influence in reducing excessive cost of living for many of our people. it will not, of course, solve the problem of increasing the number of farms and the area of cultivation to meet the needs of growing population. neither will it enable us to expand our home market rapidly and largely enough to keep the country on an even keel of prosperity. we must go forward with the development of natural resources as we have done for the past three centuries. and we must recognize at the outset that conditions have changed with the depletion of the public domain to the point where it offers comparatively little in the way of cultivable lands. we have now to deal principally with lands in private ownership. this calls for a new point of view and for the application of a somewhat different principle than that which has governed our reclamation policy heretofore. moreover, reclamation is no longer an affair of one section of the united states. the day has come when it must be nationalized and extended to all parts of the republic. to the deserts of the west we have brought the creative touch of water, and we must find a way to go on with this work. but it is of equal importance that we should liberate rich areas now held in bondage by the swamp, convert millions of acres of idle cut-over lands to profitable use, and raise from the dead the once vigorous agricultural life of our abandoned farms. one more fundamental consideration--we have outlived our day of small things. whether we would or not, we are compelled by the inexorable law of necessity arising out of existing physical conditions to cooperate, to work together, and to employ large-scale operations, and on this principle we should move: not what the government can do for the people, but what the people can do for themselves under the intelligent and kindly leadership of the government. we have an instrument at hand in the reclamation service which has dealt with every phase of the problem which now confronts us, and with such high average success as to command the entire confidence of congress and the country. it has turned rivers out of their natural beds, reared the highest dams in existence, transported water long distances by every form of canal, conduit, and tunnel, installed electric power plants, cleared land, provided drainage systems, constructed highways and even railroads, platted townsites, and erected buildings of various sorts. in this experience, obtained under a variety of physical and climatic conditions, it has developed a body of trained men equal to any constructive task which may be assigned to it in connection with reclamation and settlement in any part of the country. true economic reclamation is a process of converting liabilities into assets--of transforming dormant natural resources into agencies of living production. when such a process is intelligently applied it should be able to pay its own bills without placing fresh burdens on the national treasury. it is in the confident belief that such is actually the case that i suggest the policy of reclamation by means of local districts, financed on the basis of their own credit but with the fullest measure of encouragement and moral support of the government, practically expressed through the reclamation service. in this connection it seems worth while to recall that with a net expenditure of $ , , the reclamation service has created taxable values of $ , , in the states where it has operated. the ratio is better than three to one, and that is a wider margin of security than is usually demanded by the most conservative banking methods. there is no reason to doubt that the overflow lands of the south, the cut-over areas of the northwest, and the abandoned farm districts of new england and new york and other states would do quite as well as the deserts of the west if handled by such an organization. what is the legitimate function of the government in connection with reclamation districts to be financed entirely upon their own credits without the aid of national appropriations? i should say that the government, with great advantage to the investor, the landowner, the future settler, and the general public, might do these things: . employ its trained, experienced engineers, attorneys, and economists in making a thorough investigation of all the factors involved in a given situation, to be followed by a thorough official report upon the district proposed to be formed. . offer the district securities for public subscription in the open market. this, of course, would follow the actual organization of the district and the approval of its proceedings by the government's legal experts. . construct the works of reclamation with proceeds of district bond sales, and administer the system until it becomes a "going concern," when it may be safely confided to its local officers. the most obvious advantage of government cooperation is the fact that it would assure the service of a body of engineers, builders, and administrators trained in the actual work of reclamation. this advantage, as compared with the management that might be had in a sparsely settled local district, would often make all the difference between success and failure. unquestionably it would materially reduce the interest rate on district bonds and greatly facilitate their sale in the open market. there are other advantages less obvious but really more important. experience has shown that great enterprises can best be handled under centralized control. this control, to be effective, must extend from the initiation to the completion of the project. there can be no assurance of this when the management is left to the electorate of a local district, and without such assurance it is difficult to command the support, first, of the landowners whose consent is essential to the formation of the district; next, of the investors who must supply the money; finally, of the settlers who must purchase and develop the land in order that the object of the enterprise may be realized. the government can give the assurance of precisely that quality of unified, centralized, permanent, and responsible control that is required to command the confidence of all the factors in the situation. there is another advantage of government cooperation that will inure greatly to the benefit of the settler. the government may readily apply the policy it now uses in connection with privately owned lands within reclamation projects. it requires the owners to enter into a contract by which they agree to accept a certain maximum price for their land if sold within a given period of years. this price is based upon the value of the land before reclamation. there are many instances, particularly of swamp and cut-over areas, where land that may be bought for $ an acre and reclaimed at a cost of $ to $ per acre, has an actual market value of $ to $ per acre the moment it is put into shape for cultivation. if the government, by means of a contract with the local district, undertakes the work of reclamation and settlement and does this work at actual cost, the settler will generally save enough to pay for all his improvements and equipment. the crowning consideration is the fact that, because of all these advantages, the work of reclamation would actually be accomplished, while to-day it is not being done except in the far west, and accomplished without the aid of government appropriations. soldier-settlement legislation. in the foregoing, attention has been called to those things which may be accomplished by the exercise of the government's powers of supervision and direction with the smallest outlay of money. in all this i have been speaking of reclamation for the sake of reclamation. the proposed soldier-settlement legislation stands on an entirely different footing. the primary object is not to reclaim land but to reward our returned soldiers with the opportunity to obtain employment and larger interest in the proprietorship of the country. the policy is based on a sense of gratitude for heroic service, not on economic considerations. this is the answer to those who have criticized it as class legislation or the proposal to grant special privileges to one element of our citizenship or as a plunge into socialism. frankly, we avow our purpose to do for the soldier what we would not think of doing for anybody else and what would not be justified solely as a matter of reclamation. many measures of soldier legislation have been introduced into congress. only one of these has been favorably reported. this was introduced by representative mondell, of wyoming, on the first day of the present special session, embodying the plan of reclamation and community settlement brought forward by this department in the spring of . the measure has been much misunderstood and sometimes deliberately misrepresented. in the first place, it was not put forward as the complete solution of the soldier problem. it was at no time supposed or expected that all of the , , men and women engaged in the war with germany would or could take advantage of its provisions. it fortunately happens that the vast majority quickly found their places in the national life. of the remainder, a very large proportion may be classified as "city minded." they have no taste for farm life but would be better served by vocational training and opportunities to enter upon remunerative trades or professions. there is an element of "country minded," and of these some , have made application for opportunities of employment and home-making under the terms of this bill. largely they are men who have had agricultural experience but who can not obtain farms of their own without very considerable cash advances and other assistance which the government could render. it is for this element that the policy is designed. it has often been said that the plan would be applied only in the west and south. the truth is that it has been the purpose from the first to extend it to every state where feasible projects could be found, and that our preliminary investigations lead us to believe this will include every state in the union. the wide discussion of the measure has been highly educational to the country, and some of the criticism is of constructive character. for example, attention has been sharply called to the fact that in certain localities there are individual farms well suited to our purpose which may often be had at a price representing rather less than the value of their improvements. these are the so-called "abandoned farms" so numerous in the northeastern states. in some cases they are interspersed with land now cultivated, so situated that it is not possible to bring together a large number of contiguous farms as the basis of a government project. in new england and elsewhere public sentiment strongly favors a modification of the pending measure which will enable the purchase of individual farms rather than community settlement. this would be practicable only in localities where a sufficient number of farms, even if not contiguous, could be had to make possible the necessary supervision and instruction, together with cooperative organization for the purchase of supplies and sale of products. without these advantages the plan of soldier settlement would fail in many instances. my information is that these conditions could be met. not only so, but it is urged that existing farm communities would be inspired by the presence of soldier settlers and benefited by the presence of soldier settlers by their cooperative buying and selling agencies. another criticism of the pending measure is directed to the amount of the first payment the soldier settler is required to make. as the bill now stands it calls for per cent on the land, per cent on improvements and live stock, and per cent on implements and other equipment. it has been urged by some friends of soldier settlement that no first payment should be required, but that the government should make advances of per cent in view of the soldiers' peculiar claim upon national consideration. it might be feasible to do this in the case of community settlements. but it could not be done in the case of scattered and individual farms, at least without abandoning the principles of sound business. in the case of community settlement the soldier literally "gets in on the ground floor." starting with a territory that is entirely blank so far as homes and improvements are concerned, he finds himself in a place where community values remain to be created. when he buys an improved farm in a settled neighborhood the situation is precisely reversed. in both cases there is or will be "unearned increment," or society-created values; but in the one case he _gets_ the increment, while in the other case he _pays_ it. obviously, a larger advance would be justified in one case than in the other. alaska. one of the first recommendations made by me in my report of seven years ago was that the government build a railroad from seward to fairbanks in alaska. five years ago you intrusted to me the direction of this work. the road is now more than two-thirds built, and congress at this session, after exhaustively examining into the work, has authorized an additional appropriation sufficient for its completion. the showing made before congress was that the road had been built without graft: every dollar has gone into actual work or material. it has been built without giving profits to any large contractors, for it has been constructed entirely by small contractors or by day's labor. it has been built without touch of politics: every man on the road has been chosen exclusively for ability and experience. it has been well and solidly built as a permanent road, not an exploiting road. it has been built for as little money as private parties could have built it, as all competent independent engineers who have seen the road advise. edwin f. wendt, of the interstate commerce commission, in charge of valuation of the railroads of the united states from pittsburgh to boston, after an investigation into the manner in which the alaskan railroad was constructed and its cost, reported to me as follows: in concluding, it is not amiss to again state that after the full study which was given to the property during our trip, we are satisfied that the project is being executed rapidly and efficiently by men of experience and ability. it is believed that it is being handled as cheaply as private contractors could handle it under the circumstances. the road has not been built as soon as expected because each year we have exhausted our appropriation before the work contemplated had been done. we could not say in october of one year what the cost of anything a year or more later would be, and we ran out of money earlier than anticipated. it has not been built as cheaply as expected because it has been built on a rising market for everything that went into its construction--from labor, lumber, food supplies, machinery, and steel to rail and ocean transportation. i believe, however, it can safely be said that no other piece of government construction or private construction done during the war will show a less percentage of increase over a cost that was estimated more than four years ago. the men have been well housed and well fed. their wages have been good and promptly paid; there has been but one strike, and that was four years ago and was settled by department of labor experts fixing the scale of wages. the men have had the benefit of a system of compensation for damages like that in the reclamation service and panama canal. they have had excellent hospital service, and our camps and towns have been free of typhoid fever and malaria. that the men like the work is testified by the fact that hundreds who "came out" the past two years, attracted by the high wages of war industries, are now anxious to return to alaska. there has been but one setback in the construction, and that was the washing out of miles of tracks along the nenana river. this is a glacial stream which, when the snows melt, comes down at times with irresistible force. in this instance it abandoned its long accustomed way and cut into a new bed and through trees that had been standing for several generations, tearing out part of the track which had been laid. the work of locating and constructing the road has been left in the hands of the engineers appointed by yourself. the only instruction which they received from me was that they should build the road as if they were working for a private concern, selecting the best men for the work irrespective of politics or pressure of any kind. as a result, we have a force that has been gathered from the construction camps of the western railroads, made up of men of experience and proved capacity. that they have done their work efficiently, honestly, and at reasonable cost is my belief. it is not possible during the construction of a railroad to tell what it costs per mile because all the foundation work, the construction of bases from which to work, the equipment for construction, and much of the material is a charge which must be spread over the entire completed line. the best estimate that can be made to-day as to the newly constructed road is that it has cost between $ , and $ , per main-line mile, or between $ , and $ , per mile of track. this cost per mile includes the building of the most difficult and expensive stretch of line along the entire route from seward to fairbanks--that running along turnagain arm, which is sheer rock rising precipitously from the sea for nearly miles. there are miles of this road which have cost $ , per mile. even to blast a mule trail in one portion of this route cost $ , a mile. the only government-built railroad--that across the isthmus of panama--cost $ , per mile. the only two recently built railroads in the united states are ( ) the virginian, built by h.h. rogers, which cost exclusive of equipment $ , per mile, with labor at from $ . to $ . per day and all machinery, fuel, rails, and supplies at its door, and ( ) the milwaukee line to puget sound, which is estimated as having cost $ , per mile exclusive of equipment. the work has been conducted with its main base at anchorage, which is at the head of cook inlet. the point was chosen as the nearest point from which to construct a railroad into the matanuska coal fields. that was the primary objective of the railroad, to get at the matanuska coal. from anchorage it was also intended to drive farther north through the susitna valley and across broad pass, and to the south along turnagain arm toward the alaska northern track. to secure coal for alaska was the first need. so in addition to anchorage as a base, one was also started at nenana, on the tanana river, from which to reach the nenana coal fields lying to the south. if these two fields were open, one would supply the coast of alaska and one the interior. this program has been acted upon, with the result that the matanuska field is open to tidewater with a downgrade road all the way. the nenana road has been pushed far enough south to touch a coal mine near the track, which may obviate the immediate necessity for reaching into the nenana field proper. there is an open stretch across broad pass to connect the susitna valley with the road coming down from nenana. this gap closed, there will be through connection between seward and fairbanks. matanuska coal. by decisions of the commissioner of the land office all of the claims in the matanuska coal field were set aside, and by act of congress a leasing bill was put into effect over the entire field. under this law a number of claims must be reserved to the government. the field was surveyed, and some of the most promising portions of the field have been so reserved. two leases have been entered into by the government, one with lars netland, a miner, who has a backer, mr. fontana, a business man of san francisco, and the other with oliver la duke and associates. there are many thousands of acres in this field which are open for lease and which will be leased to any responsible parties who will undertake their development. government experts who have examined this field do not promise without further exploring a larger output of coal from this field than , tons a year. the population of alaska has fallen off during the war. she sent, i am told, , men into the army, the largest proportion to population sent by any part of the united states. the high cost of labor and materials closed some of the gold mines, and the attractive wages offered by war industries drew labor from alaska to the mainland. all prospecting practically closed. but with the return of peace there is evidence of a new movement toward that territory which should be given added confidence in its future by the completion of the alaskan railroad. there is enough arable land in alaska to maintain a population the equal of all those now living in norway, sweden, and finland, and all that can be produced in those countries can be produced in alaska. the great need is a market, and this will be found only as the mining and fishing industries of the country develop. save and develop americans. when the whole story is told of american achievement and the picture is painted of our material resources, we come back to the plain but all-significant fact that far beyond all our possessions in land and coal and waters and oil and industries is the american man. to him, to his spirit and to his character, to his skill and to his intelligence is due all the credit for the land in which we live. and that resource we are neglecting. he may be the best nurtured and the best clothed and the best housed of all men on this great globe. he may have more chances to become independent and even rich. he may have opportunities for schooling nowhere else afforded. he may have a freedom to speak and to worship and to exercise his judgment over the affairs of the nation. and yet he is the most neglected of our resources because he does not know how rich he is, how rich beyond all other men he is. not rich in money--i do not speak of that--but rich in the endowment of powers and possibilities no other man ever was given. twenty-five per cent of the , , men between and years of age who were first drafted into our army could not read nor write our language, and tens of thousands could not speak it nor understand it. to them the daily paper telling what von hindenberg was doing was a blur. to them the appeals of hoover came by word of mouth, if at all. to them the messages of their commander in chief were as so much blank paper. to them the word of mother or sweetheart came filtering in through other eyes that had to read their letters. now this is wrong. there is something lacking in the sense of a society that would permit it in a land of public schools that assumes leadership in the world. here is raw material truly, of the most important kind and the greatest possibility for good as well as for ill. save! save! save! this has been the mandate for the past two years. it is a word with which this report is replete. but we have been talking of food and land and oil while the boys and young men that are about us who carry the fortune of the democracy in their hands are without a primary knowledge of our institutions, our history, our wars and what we have fought for, our men and what they have stood for, our country and what its place in the world is. the marvelous force of public opinion and the rare absorbing quality of the american mind never was shown more clearly than by the fact that out of these men came a loyalty and a stern devotion to america when the day of test came. had germany known what we know now, it would have been beyond her to believe that america could draft an army to adventure into war in europe. there should not be a man who was in our army or our navy who has the ambition for an education who should not be given that opportunity--indeed, induced to take it--not merely out of appreciation but out of the greater value to the nation that he would be if the tools of life were put into his hand. there is no word to say upon this theme of americanization that has not been said, and congress, it is now hoped, will believe those figures which, when presented nearly two years ago, were flouted as untrue. the nation is humiliated at its own indifference, and action must be the result. to save and to develop, i have said, were equally the expression of a true conservation. what is true as to material things is true as to human beings. and once given a foundation of health there is no other course by which this policy may be effected than to place at the command of every one the means of acquiring knowledge. the whole people must turn in that direction. we should enable all, without distinction, to have that training for which they are fitted by their own natural endowment. then we can draw out of hiding the talents that have been hidden. the school will yet come to be the first institution of our land, in acknowledged preeminence in the making of americans who understand why they are americans and why to be one is worth while.[ ] footnotes [ ] extract from the annual report of the secretary of the interior for the fiscal year ended june , . the page numbers are the same as those in the report. [ ] in spite of the strike order, effective the last day of the week, the production of soft coal during the seven days oct. -nov. was greater than in any week this year save one. the exception was the preceding week, that of oct. , which full reports now confirm as the record in the history of coal mining in the united states. the total production during the week ended nov. (including lignite and coal made into coke) is estimated at , , net tons, an average per working day of , , tons. indeed had it not been for the strike, curtailing the output of saturday, the week of nov. would have far outstripped its predecessor. the extraordinary efforts made by the railroads to provide cars bore fruit in a rate of production during the first five days of the week which, if maintained for the working days of full-time year, would yield , , tons of coal. it is worth noting that this figure is almost identical with the , , tons accepted early in by the geological survey and the railroad administration as representing the country's annual capacity. during these five days, therefore, the soft-coal mines were working close to actual capacity. there can be little doubt that the output on monday, oct. , was the largest ever attained in a single day. (u.s. geol. survey bull.) [ ] it is the western and southern fields that are most affected by the seasonal demand. as a typical example, illinois may be cited, with per cent of the year's production in per cent of the time, april, may, and june, in , and per cent in . retail dealers received per cent of the coal from illinois in the period from august, , to february, , compared with per cent from the pittsburgh, pa., field. [ ] in every trainload of coal hauled from the mines to our coal bins, carload out of every is going nowhere. in a train of cars, the last are dead load that might better have been left in the bowels of the earth. no less an authority than martin a. rooney states: "every fifth shovel full of coal that the average fireman throws into his furnace serves no more useful purpose than to decorate the atmosphere with a long black stream of precious soot. at best one-fifth of all our coal is wasted." the first requisite toward effecting fuel economy is to secure cooperation between owners, managers, and the men who fire the coal. mechanical devices to increase efficiency in the use of coal can not produce satisfactory results unless the operators who handle them are impressed with the importance of their duties. it is not essential for the plant manager to be a fuel expert, but he should be familiar with the instruments that give a check on the daily operations. it is a mistake not to provide proper instruments, for they guide the firemen and show the management what has taken place daily. instruments provided for the boiler room manifest the interest taken by the management toward conserving fuel. it indicates cooperation and encourages the firemen to work harder to increase the efficiency. a second factor effecting fuel economy is the selection of fuel for the particular plant. it is not expected of a plant manager that he should be thoroughly informed as to the character of all fuels; but he can enlist the services of a man who is thoroughly trained in this field. the bureau of mines has compiled valuable information on the character and analyses of coal from almost every field in the united states. information concerning the character and chemical constituents of the coal, together with knowledge pertaining to the equipment of the plant, makes it possible to select a fuel adapted to the equipment, thereby insuring better combustion. hundreds of boiler plants operate at no greater than per cent efficiency, and it would be a comparatively simple matter to bring them up to per cent efficiency. the saving in tonnage would be more than the combined yearly coal-carrying capacity of the baltimore & ohio and the southern railway systems. the direct saving to our industries at $ per ton would amount to $ , , worth of coal per year. [ ] assistant secretary herbert kaufman before the senate committee on education presented facts and figures which accentuate the seriousness of the national situation. among other things he said: "the south leads in illiteracy, but the north leads in non-english speaking. over per cent of the persons in the east-south central states have never been to school. approximately per cent of the people of passaic, n.j., must deal with their fellow workers and employers through interpreters. and per cent of the folk in lawrence and fall river, mass., are utter strangers in a strange land. "the extent to which our industries are dependent upon this labor is perilous to all standards of efficiency. their ignorance not only retards production and confuses administration, but constantly piles up a junk heap of broken humans and damaged machines which cost the nation incalculably. "it is our duty to interpret america to all potential americans in terms of protection as well as of opportunity; and neither the opportunities of this continent nor that humanity which is the genius of american democracy can be rendered intelligible to these , , until they can talk and read and write our language. "steel and iron manufacturers employ per cent of foreign-born helpers; the slaughtering and meat-packing trades, per cent; bituminous coal mining, per cent; the silk and dye trade, per cent; glass-making enterprises, per cent; woolen mills, per cent; cotton factories, per cent; the clothing business, per cent; boot and shoe manufacturers, per cent; leather tanners, per cent; furniture factories, per cent; glove manufacturers, per cent; cigar and tobacco trades, per cent; oil refiners, per cent; and sugar refiners, per cent. "you will agree with me that future security compels attention to such concentrations of unread, unsocialized masses thus conveniently and perilously grouped for misguidance. "they live in america, but america does not live in them. how can all be 'free and equal' until they have free access to the same sources of self-help and an equal chance to secure them? "illiteracy is a pick-and-shovel estate, a life sentence to meniality. democracy may not have fixed classes and survive. the first duty of congress is to preserve opportunity for the whole people, and opportunity can not exist where there is no means of information. "it is a shabby economy, an ungrateful economy that withholds funds for their betterment. the fields of france cry shame upon those who are content to abandon them to their handicap. "the loyal service of immigrant soldiers and sailors commit us to instruct and nationalize their brothers in breed. "the spirit in which these united states were conceived insists that the republic remove the cruel disadvantage under which so many native borns despairingly carry on. "how may they reason soundly or plan sagely? the man who knows nothing of the past can find little in the future. the less he has gleaned from human experience the more he may be expected to duplicate its signal errors. no argument is too ridiculous for acceptance; no sophistry can seem far-fetched to a person without the sense to confound it. "anarchy shall never want for mobs while the uninformed are left at the mercy of false prophets. those who have no way to estimate the worth of america are unlikely to value its institutions fairly. blind to facts, the wildest one-eyed argument can sway them. "not until we can teach our illiterate millions the truths about the land to which they have come and in which they were born shall its spirit reach them--not until they can read can we set them right and empower them to inherit their estate. "if we continue to neglect them, there are influences at work that will sooner or later convince them who now fail to appreciate the worth of our government that the government itself has failed--crowd the melting pot with class hates and violence and befoul its yield. "we must not be tried by inquest. we demand the right to vindicate the merit of our systems wherever their integrity is questioned or maligned. "we demand the right to regulate the cheating scales upon which the republic is weighed by its ill-wishers. "we demand the right to protect unintelligence from esau bargains with hucksters of traitorous creeds. "we demand the right to present our case and our cause to the unlettered mass, whose benightedness and ready prejudices continually invite exploitation. "we demand the right to vaccinate credulous inexperience against bolshevism and kindred plagues. "we demand the right to render all whose kind we deem fit to fight for our flag fit to vote and prosper under its folds. "we demand the right to bring the american language to every american, to qualify each inhabitant of these united states for self-determination, self-uplift, and self-defense." dr. philander p. claxton, commissioner of education, in his analysis of the illiteracy figures of the census, said: "illiteracy is not confined to any one race or class or section. of the , , illiterates as reported by the census of , nearly , , were whites, and more than , , were native-born whites. "that illiteracy is not a problem of any one section alone is shown by the fact that in massachusetts had , more illiterate men of voting age than arkansas; michigan, , more than west virginia; maryland, , more than florida; ohio, more than twice as many as new mexico and arizona combined; pennsylvania, , more than tennessee and kentucky combined. boston had more illiterates than baltimore, pittsburgh more than new orleans, fall river more than birmingham, providence nearly twice as many as nashville, and the city of washington , more than the city of memphis. "it is especially significant that of the , , native-born white illiterates reported in the census , , , about . per cent, were in the open country and small towns, and only , , or . per cent, were in cities having a population of , and over. of the , , illiterate negroes , , , or . per cent, were in the country, and only , , or . per cent, were in the cities." additional copies of this publication may be procured from the superintendent of documents government printing office washington, d.c. at cents per copy transcriber's note emphasized text denoted as _italic_ and =bold= respectively. cambridge natural science manuals. geological series. the principles of stratigraphical geology london: c. j. clay and sons, cambridge university press warehouse, ave maria lane. and h. k. lewis, , gower street, w.c. [illustration] leipzig: f. a. brockhaus. new york: the macmillan company. bombay: e. seymour hale. the principles of stratigraphical geology by j. e. marr, m.a., f.r.s. fellow and lecturer of s. john's college, cambridge, and university lecturer in geology. cambridge: at the university press. [_all rights reserved._] cambridge: printed by j. & c. f. clay, at the university press. preface. the present work has been written in order that students may gain by its perusal some idea of the methods and scope of stratigraphical geology. i believe that this idea can be obtained most satisfactorily, if a large number of the details connected with the study of the stratified rocks are omitted, and i have accordingly given very brief accounts of the strata of the different systems. the work is intended for use in conjunction with any book which treats of the strata of the geological column at considerable length; some of these books are mentioned on pages , . j. e. m. cambridge, _november, _. contents. page chapter i. introduction chapter ii. account of the growth and progress of stratigraphical geology chapter iii. nature of the stratified rocks chapter iv. the law of superposition chapter v. the test of included organisms chapter vi. methods of classification of the strata chapter vii. simulation of structures chapter viii. geological maps and sections chapter ix. evidences of conditions under which strata were formed chapter x. evidences of conditions under which strata were formed, continued chapter xi. the classification of the stratified rocks chapter xii. the precambrian rocks chapter xiii. cycles of change in the british area chapter xiv. the cambrian system chapter xv. the ordovician system chapter xvi. the silurian system and the changes which occurred in britain at the close of silurian times chapter xvii. the devonian system chapter xviii. the carboniferous system chapter xix. the changes which occurred during the third continental period in britain; and the foreign permo-carboniferous rocks chapter xx. the permian system chapter xxi. the triassic system chapter xxii. the jurassic system chapter xxiii. the cretaceous system chapter xxiv. the eocene rocks chapter xxv. the oligocene and miocene periods chapter xxvi. the pliocene beds chapter xxvii. the pleistocene accumulations chapter xxviii. the steppe period chapter xxix. the forest period chapter xxx. remarks on various questions addenda et corrigenda. [tn: corrections made!] p. , line from bottom: for 'joining' read 'jointing' p. , line from bottom: for 'dr' read 'messrs medlicott and' p. , line from bottom: after 'permo-carboniferous strata' insert 'through the permian' p. , last line of footnote: for 'dr' read 'messrs medlicott and' " insert a second footnote: 'for information concerning the permian volcanic rocks see sir a. geikie's _ancient volcanoes of great britain_.' p. , insert a footnote: 'a good account of the british jurassic rocks will be found in mr h. b. woodward's memoir on "the jurassic rocks of britain." _mem. geol. survey_, --.' p. , top line: for 'gardiner' read 'gardner' chapter i. introduction. it is the aim of the stratigraphical geologist to record the events which have occurred during the existence of the earth in the order in which they have taken place. he tries to restore the physical geography of each period of the past, and in this way to write a connected history of the earth. his methods are in a general way similar to those of the ethnologist, the archæologist, and the historian, and he is confronted with difficulties resembling those which attend the researches of the students of human history. foremost amongst these difficulties is that due to the imperfection of the geological record, but similar difficulty is felt by those who pursue the study of other uncertain sciences, and whilst this imperfection is very patent to the geologist, it is perhaps unduly exaggerated by those who have only a general knowledge of the principles and aims of geology. the history of the earth, like other histories, is a connected one, in which one period is linked on to the next. this was not always supposed to be the case; the catastrophic geologist of bygone times believed that after each great geological period a convulsion of nature left the earth's crust as a _tabula rasa_ on which a new set of records was engraved, having no connexion with those which had been destroyed. careful study of the records of the rocks has proved that the conclusions of the catastrophists were erroneous, and that the events of one period produce their impression upon the history of the next. every event which occurs, however insignificant, introduces a new complication into the conditions of the earth, and accordingly those conditions are never quite the same. although the changes were no doubt very slow, so that the same general conditions may be traced as existent during two successive periods, minor complications occurred in the inorganic and organic worlds, and we never get an exact recurrence of events. vegetable deposits may now be in process of accumulation which in ages to come may be converted into coal, but the general conditions which were prevalent during that carboniferous period when most of our workable coal was deposited do not now exist, and will never exist again. the changes which have taken place and which are taking place show an advance from the simple to the more complex, and the stratigraphical geologist is confronted with a problem to which the key is development, and it is his task to trace the development of the earth from the primitive state to the complex condition in which we find it at the present day. our general ignorance of the events of the earliest periods of the history of the earth will be emphasised in the sequel, and it will be found that the complexity which marks the inorganic and organic conditions which existed during the deposition of the earliest rocks of which we have detailed knowledge points to the lapse of enormous periods of time subsequent to the formation of the earth, and previous to the deposition of those rocks. the imperfection of the record is most pronounced for that long period of time, but in this respect the geologist is in the same condition as the student of human history, for the relics of the early stone age prove that man in that age had attained a fairly high state of civilisation, and the gap which separates palæolithic man from the first of our race is relatively speaking as great as that which divides the cambrian period from the commencement of earth-history. nevertheless, human history is a science which has made gigantic strides towards the solution of many problems connected with the development of man and civilisation, and similarly geology has advanced some way in its task of elucidating the history of our globe. the task of the stratigraphical geologist is two-fold. in the first place, he must establish the order of succession of the strata, for a correct chronology is of paramount importance to the student of earth-lore. the precautions which must be taken in making out the order of deposition of the rocks of any area, and correlating those of one area with those of another will be considered in the body of the work. when this task is completed, there yet remains the careful examination of all the information supplied by a study of the rocks of the crust, in order to ascertain the actual conditions which existed during the deposition of any stratum or group of strata. in practice, it is generally very difficult to separate these two departments of the labour of the stratigraphical geologist, and the two kinds of work are often done to a large extent simultaneously, or sometimes alternately. frequently the general succession of the deposits comprising an important group is ascertained, and at the same time observations made concerning the physical characters of the deposits and the nature of their included organisms, which are sufficient to afford some insight into the general history of the period when these deposits were laid down; a more detailed classification of the same set of deposits may be subsequently made, and as the result of this, more minute observations as to the variations in the physical and biological conditions of the period are possible, which permit us to write a much more concise history of the period. so great has been the tendency to carry on work in a more and more detailed manner, that it is very difficult if not impossible to tell when any approach to finality is reached in the study of a group of strata in any area. roughly speaking, we may state that our knowledge of a group of strata is obtained by three processes, or rather modifications of one process. the general order of succession is established by the pioneer, frequently as the result of work carried on through one or two seasons. subsequently to this, a more minute subdivision of the rocks is possible as the result of labours conducted by one or more workers who are enabled to avail themselves of the work of the pioneer, and our knowledge of the rocks is largely increased thereby. but the minutiæ, often of prime importance, are supplied by workers who must spend a large portion of their time in the area where the work lies, and it is only in districts where work of this character has been performed, that our knowledge of the strata approaches completion. the strata of the arctic regions, for example, have in many places been examined by pioneers, but a great deal remains to be done in those regions; the main subdivisions only have been defined in many cases, and our information concerning the physical history of arctic regions in past times is comparatively meagre. to come nearer home--a few miles north of cambridge lies the little patch of corallian rock at upware; it has been frequently visited, and a large suite of organic remains extracted from it, but no one has devoted the time to the collection of remains from this deposit which has been devoted to that of some other formations presently to be mentioned, and accordingly our knowledge of the fauna of that deposit is far from complete. contrast with this the information we possess of the little seam known as the cambridge greensand, from which organic remains have been sedulously collected during the extensive operations which have been carried on for the extraction of the phosphatic nodules which occur in the seam. the suite of relics of the organisms of that period is accordingly far more perfect than in the case of many other beds, and indeed the large and varied collection of relics of the vertebrata of the period which furnish much information of value to the palæontologist would not have been gathered together, had not this seam been so carefully worked, and an important paragraph in the chapter bearing on the history of this period would have remained unknown to us. again, two little patches of limestone of the same age, one in central england and the other in the island of gothland, have been the objects of sedulous inquiry by local observers, and we find again that our knowledge of the physical history of the period, as regards these two regions, is exceptionally perfect. special stress is laid upon this point, for in these days, when every county possesses its learned societies whose members are desirous of advancing in every possible way the progress of science, it is well to insist upon the importance of this detailed work which can only be done by those who have a large amount of time to devote to the rigorous examination of the rocks of a limited area. chapter ii. account of the growth and progress of stratigraphical geology. the history of the growth of a science is not always treated as an essential part of our knowledge of that science, and many text-books barely allude to the past progress of the science with which they deal. the importance of a review of past progress has, however, attracted the attention of many geologists, and sir charles lyell, in his _principles of geology_, gave prominence to an historical sketch of the rise and progress of the science. historical studies of this nature have more than an academic value; the very errors made by men in past times are useful as warnings to prevent those of the present day from going astray; the lines along which a science has progressed in the past may often be used as guides to indicate how work is to be conducted in the future; but perhaps the greatest lesson which is taught by a careful consideration of the rise and progress of a study is one which has a moral value, for he who pays attention to the growth of his science in past times, gains a reverence for the old masters, and at the same time learns that a slavish regard for authority is a dangerous thing. this is a lesson which is of the utmost importance to the student who wishes to advance his science, and will prevent him from paying too little attention to the work of those who have gone before him, whilst it will enable him to perceive that as great men have fallen into error through not having sufficient data at their disposal, he need not be unduly troubled should he find that conclusions which he has lawfully attained after consideration of evidence unknown to his predecessors clash with those which they adopted. want of this historic knowledge has no doubt caused many workers to waste their time on work which has already been performed, but it has also led others to withhold important conclusions from their fellow-workers because they were supposed to be heterodox. in an uncertain science like geology one of the great difficulties is to keep an even balance between contempt and undue respect for authority, and assuredly a scientific study of the past history of a science will do much to enable a student to attain this end. it will be useful, therefore, at this point to give a brief account of the rise and progress of the study of stratigraphical geology, so far as that can be done without entering into technical details, at the same time recommending the student to survey the progress of this branch of our science for himself, after he has mastered the principles of the subject, and such details as are the property of all who have studied the science from the various text-books written for advanced students. william smith, the 'father of english geology,' is rightly regarded as the founder of stratigraphical geology on a true scientific basis, but like all great discoverers, his work was foreshadowed by others, though so dimly, that this does not and cannot detract from his fame. it is desirable, however, to begin our historical review at a time somewhat further back than that at which smith gave to the world his epoch-making map and memoirs. before the eighteenth century, stratigraphical geology cannot be said to have existed as a branch of science--the way had not been prepared for it. data had been accumulated which would have been invaluable if at the disposal of open-minded philosophers, but with few exceptions prejudice prevented the truth from becoming known. there were two great stumbling-blocks to the establishment of a definite system of stratigraphical geology by the writers of the middle ages, firstly, the contention that fossils were not the relics of organisms, and, secondly, when it was conceded that they represented portions of organisms which had once existed, the assertion that they had reached their present positions out of reach of the sea during the noachian deluge. for full details concerning the mischievous effects of these tenets upon the science the reader is referred to the luminous sketch of the growth of geology in the first four chapters of sir charles lyell's _principles of geology_. the disposition of rocks in strata, and the occurrence of different fossils in different strata, was known to woodward when he published his _essay toward a natural history of the earth_ in , and the valuable collections made by woodward and now deposited in the woodwardian museum at cambridge, show how fully he appreciated the importance of these facts, though he formed very erroneous conclusions from them, owing to the manner in which he drew upon his imagination when facts failed him, maintaining that fossils were deposited in the strata according to their gravity, the heaviest sinking first, and the lightest last, during the time of the universal deluge. the following extracts from part ii. of woodward's book, show the position in which our knowledge of the strata stood at the end of the seventeenth century: "the matter, subsiding ..., formed the _strata_ of stone, of marble, of cole, of earth, and the rest; of which strata, lying one upon another, the terrestrial globe, or at least as much of it as is ever displayed to view, doth mainly consist.... the shells of those cockles, escalops, perewinkles, and the rest, which have a greater degree of gravity, were enclosed and lodged in the _strata_ of stone, marble, and the heavier kinds of terrestrial matter: the lighter shells not sinking down till afterwards, and so falling amongst the lighter matter, such as chalk, and the like ... accordingly we now find the lighter kinds of shells, such as those of the _echini_, and the like, very plentifully in chalk.... humane bodies, the bodies of quadrupeds, and other land-animals, of birds, of fishes, both of the cartilaginous, the squamose, and crustaceous kinds; the bones, teeth, horns, and other parts of beasts, and of fishes: the shells of land-snails: and the shells of those river and sea shell-fish that were lighter than chalk &c. trees, shrubs, and all other vegetables, and the seeds of them: and that peculiar terrestrial matter whereof these consist, and out of which they are all formed, ... were not precipitated till the last, and so lay above all the former, constituting the supreme or outmost _stratum_ of the globe.... the said _strata_, whether of stone, of chalk, of cole, of earth, or whatever other matter they consisted of, lying thus each upon other, were all originally parallel: ... they were plain, eaven, and regular.... after some time the _strata_ were broken, on all sides of the globe: ... they were dislocated, and their situation varied, being elevated in some places, and depressed in others ... the agent, or force, which effected this disruption and dislocation of the _strata_, was seated _within_ the earth." woodward's writings no doubt exercised a direct influence on the growth of our subject, but the indirect effects of his munificent bequest to the university of cambridge and his foundation of the chair of geology in that university were even greater, for as will be pointed out in its proper place, two of the occupants of that chair played a considerable part in raising stratigraphical geology to the position which it now occupies. the discoveries which were made after the publication of woodward's book and before the appearance of the map and writings of william smith are given in the memoir of the latter author, written by his nephew, who formerly occupied the chair of geology at oxford[ ]. it would appear that the fact that "the strata, considered as definitely extended masses, were arranged one upon another in a certain _settled order_ or _series_" was first published by john strachey in the _philosophical transactions_ for and . "in a section he represents, in their true order, chalk, oolites, lias, red marls and coal, and the metalliferous rocks" of somersetshire, but confines his attention to the rocks of a limited district. [footnote : _memoirs of william smith, ll.d._ by j. phillips, f.r.s., f.g.s. .] the rev. john michell published in the _philosophical transactions_ for an "essay on the cause and phænomena of earthquakes," but prof. phillips gives proofs that michell, who in became woodwardian professor, had before discovered (what he never published) the first approximate succession of the mesozoic rocks, in the district extending from yorkshire to the country about cambridge. michell's account was discovered written by smeaton on the back of a letter dated . the following is the succession as quoted in phillips' memoir (p. ): yards of thickness. "chalk golt sand of bedfordshire to northamptonshire lime and portland lime, lying in several strata lyas strata to sand of newark about red clay of tuxford, and several sherwood forest pebbles and gravel unequal very fine white sand uncertain roche abbey and brotherton limes coal strata of yorkshire --" the order of succession of the cretaceous, jurassic, triassic and permian beds will be readily recognised as indicated in this section, though the discovery of the detailed succession of the jurassic rocks was reserved for smith. in the year , john whitehurst published _an inquiry into the original state and formation of the earth_, containing an appendix in which the general succession of the strata of derbyshire is noted. the main points of interest are that the author clearly recognised the 'toad-stones' of derbyshire as igneous rocks, "as much a _lava_ as that which flows from hecla, vesuvius, or Ætna," though he believed that they were intrusive and not contemporaneous, and he also foreshadows the distinction between the solid strata and the superficial deposits,--"we may conclude," he says, "that all beds of sand and gravel are assemblages of adventitious bodies and not original _strata_: therefore wherever sand or gravel form the surface of the earth, they conceal the original _strata_ from our observation, and deprive us of the advantages of judging, whether coal or limestone are contained in the lower regions of the earth, and more especially in flat countries where the _strata_ do not basset." werner, who was born in , exercised more influence by his teaching than by his writings. his ideas of stratigraphical geology were somewhat vitiated by his theoretical views concerning the deposition of sediment from a universal ocean, in a definite order, beginning with granite, followed by gneiss, schists, serpentines, porphyries and traps, and lastly ordinary sediments. he recognised and taught that these rocks had a definite order "in which the remains of living bodies are successively accumulated, in an order not less determinate than that of the rocks which contain them[ ]." the limited value of werner's stratigraphical teaching is accounted for by lyell, who remarks that "werner had not travelled to distant countries; he had merely explored a small portion of germany, and conceived and persuaded others to believe that the whole surface of our planet, and all the mountain-chains in the world, were made after the model of his own province," and the author of the _principles_ justly calls attention to the great importance of travel to the geologist. those who cannot travel extensively should at any rate pay special attention to the works published upon districts other than their own, and even at the present time, the writings of some british workers are apt to be marked by some of that 'insularity' which our neighbours regard as a national characteristic. [footnote : cuvier's _eloge_.] it is now time to turn directly to the work of william smith, who, of all men, exercised the most profound influence upon the study of stratigraphical geology and may indeed be regarded as the true founder of that branch of the science. the memoir of his life which was before mentioned is all too short to illustrate the methods of work which he followed, but in it we can trace his success to three things:--firstly, his 'eye for a country,' to use a phrase which is thoroughly understood by practical geologists, though it is hard to explain to others, inasmuch as it epitomises a number of qualifications of which the most important are, a ready recognition of the main geological features from some coign of vantage, an intuitive perception of what to note and what to neglect, and the power of storing up acquired information in the mind rather than the note-book, so that one may use it almost unconsciously for future work; secondly, ability to draw conclusions from his observations, and thirdly, and perhaps most important of all in its ultimate results, a facility for checking these conclusions by means of further observations, and dropping those which were clearly erroneous, whilst extracting the truth from those which contained a germ of truth mixed with error. besides writers referred to above "some foreign writers, in particular scilla and rouelle, appear to have made very just comparisons of the natural associations of fossil shells, corals, &c. in the earth, with the groups of similar objects as they are found in the sea, and thus to have produced new proofs of the organic origin of these fossil bodies; but they give no sign of any knowledge of the _limitation of particular tribes of organic remains to particular strata_, of the _successive existence of different groups of organization_, on _successive beds of the antient sea_. mr smith's claim to this happy and fertile induction is clear and unquestionable[ ]." we get a clue to the manner in which he arrived at his view in the following passage[ ]:--"accustomed to view the surfaces of the several strata which are met with near bath uncovered in large breadths at once, mr smith saw with the distinctness of certainty, that 'each stratum had been in succession the bed of the sea'; finding in several of these strata abundance of the exuviae of marine animals, he concluded that these animals had lived and died during the period of time which elapsed between the formation of the stratum below and the stratum above, at or near the places where now they are imbedded; and observing that in the successively-deposited strata the organic remains were of different forms and structures--gryphites in the lias, trigoniæ in the inferior oolite, hooked oysters in the fuller's earth,--and finding these facts repeated in other districts, he inferred that each of the separate periods occupied in the formation of the strata was accompanied by a peculiar series of the forms of organic life, that these forms characterized those periods, and that the different strata could be identified in different localities and otherwise doubtful cases by peculiar imbedded organic remains[ ]." [footnote : _memoir of william smith_, p. .] [footnote : _ibid._ p. .] [footnote : the work of smith which directly bears upon the establishment of the law of identification of strata by included organisms is published in two treatises, entitled:-- (i) _strata identified by organized fossils_, to. (intended to comprise seven parts, of which four only were published), commenced in . (ii) _a stratigraphical system of organized fossils_, compiled from the original geological collection deposited in the british museum. to. .] william smith seems to have recognised intuitively the truth of a law which was but dimly understood before his time,--the law of superposition, which may be thus stated: "of any two strata, the one which was originally the lower, is the older." this may appear self-evident but it was certainly not so. as the result of this recognition he established the second great stratigraphical law, with which his name will ever be linked, that strata are identifiable by their included organisms. before smith's time, geological maps were lithological rather than stratigraphical, they represented the different kinds of rocks seen upon the surface without regard to their age; since smith revolutionised geology, the maps of a country composed largely of stratified rocks are essentially stratigraphical, but partly no doubt on account of adherence to old custom, partly on economic grounds, the majority of our stratigraphical maps are lithological rather than palæontological, that is the subdivisions of the strata represented upon the map are chosen rather on account of lithological peculiarities than because of the variations in their enclosed organisms. it is hardly likely that government surveys will be allowed to publish palæontological maps, which will be almost exclusively of theoretical interest, and it remains for zealous private individuals to accomplish the production of such maps. when they are produced, a comparison of stratigraphical maps founded on lithological and palæontological considerations will furnish results of extreme scientific interest. turning now from smith's contributions to the science as a whole, we may now consider what he did for british geology. his geological map was published in and was described as follows:--"a geological map of england and wales, with part of scotland; exhibiting the collieries, mines, and canals, the marshes and fen lands originally overflowed by the sea, and the varieties of soil, according to the variations of the substrata; illustrated by the most descriptive names of places and of local districts; showing also the rivers, sites of parks, and principal seats of the nobility and gentry, and the opposite coast of france. by william smith, mineral surveyor." the map was originally on the scale of five miles to an inch. in a reduced map was published, and in later years a series of county maps. he also published several geological sections, including one (in ) showing the strata from london to snowdon. the student should compare smith's map of the strata with one published in modern times in order to see how accurate was smith's delineation of the outcrop of the later deposits of our island. the following table, taken from phillips' memoir, p. , is also of interest as showing the development of smith's work and the completeness of his classification in his later years, and as illustrating how much we are indebted to smith for our present nomenclature, so much so that as prof. sedgwick remarked when presenting the first wollaston medal of the geological society to smith, "if in the pride of our present strength, we were disposed to forget our origin, our very speech would bewray us: for we use the language which he taught us in the infancy of our science. if we, by our united efforts, are chiselling the ornaments and slowly raising up the pinnacles of one of the temples of nature, it was he who gave the plan, and laid the foundations, and erected a portion of the solid walls by the unassisted labour of his hands."[ ] [footnote : the reader may consult an interesting paper by professor judd, on "william smith's manuscript maps," _geological magazine_, decade iv. vol. iv. ( ) p. .] comparative view of the names and succession of the strata. --------------------+-------------------------+-------------------------- | | improved table drawn up table drawn up | table accompanying the | in and after in . | map, drawn up in . | the first copies of the | | map had been issued. --------------------+-------------------------+-------------------------- | london clay | london clay | clay or brick-earth | sand | | crag | sand or light loam | sand chalk | chalk | chalk { upper | | { lower sand | green sand | green sand | blue marl | brick earth | purbeck stone, kentish {| sand | rag and limestone {| portland rock | of the vales {| sand | of pickering and {| oaktree clay | aylesbury, {| coral rag and pisolite | iron sand and carstone {| sand clay | dark blue shale | clunch clay and shale | | kelloway's stone | cornbrash | cornbrash sand and stone | | sand and sandstone clay | | forest marble | forest marble rock | forest marble | | clay over upper | | oolite freestone | great oolite rock | upper oolite blue clay }| | yellow clay }| | fuller's earth }| | fuller's earth and }| | rock bastard ditto }| | and sundries }| | freestone | under oolite | under oolite sand | | sand | | marlstone marl blue | blue marl | blue marl blue lias | blue lias | blue lias white lias | white lias | white lias marlstone, indigo| | and black marls | | red ground | red marl and gypsum | red marl millstone | magnesian limestone | redland limestone | soft sandstone | pennant street }| | grays }| coal districts | coal measures cliff }| | coal }| | | derbyshire limestone | mountain limestone | red and dunstone | red rhab and dunstone | killas or slate | killas | granite, sienite and | granite, sienite and | gneiss | gneiss --------------------+-------------------------+-------------------------- the above table contains a very complete classification of the british mesozoic rocks, one of the tertiary strata which is less complete, and a preliminary division of the palæozoic rocks into permian (redland limestone), carboniferous (coal measures and mountain limestone), devonian (red rhab and dunstone) and lower palæozoic (killas). since smith's time the main work which has been done in classification is a fuller elucidation of the sequence of the tertiary and palæozoic rocks, and this we may now consider. the mesozoic rocks are developed in britain under circumstances which render the application of the test of superposition comparatively simple, for the various subdivisions crop out on the surface over long distances, and the stratification is not greatly disturbed. with the tertiary and palæozoic rocks it is otherwise, for some members of the former are found in isolated patches, whilst the latter have usually been much disturbed after their formation. commencing with the tertiary deposits we may note that "the first deposits of this class, of which the characters were accurately determined, were those occurring in the neighbourhood of paris, described in by mm. cuvier and brongniart.... strata were soon afterwards brought to light in the vicinity of london, and in hampshire, which although dissimilar in mineral composition were justly inferred by mr t. webster to be of the same age as those of paris, because the greater number of fossil shells were specifically identical[ ]." it is to lyell that we owe the establishment of a satisfactory classification of the tertiary deposits which is the basis of later classifications. recognising the difficulty of applying the ordinary test of superposition to deposits so scattered as are those of tertiary age in north-west europe, he in , assisted by g. p. deshayes, proposed a classification based on the percentage of recent mollusca in the various deposits. it may be noted, that although this method was sufficient for the purpose, it has been practically superseded, as the result of increase of our knowledge of the tertiary faunas, by the more general method of identifying the various divisions by their actual fossils without reference to the number of living forms contained amongst them. the further study of the british tertiary rocks was largely carried on by joseph prestwich, formerly professor of geology in the university of oxford. [footnote : lyell, _students' elements of geology_. nd edition, p. .] amongst the palæozoic rocks, it has been seen that the permian, carboniferous and some of the devonian beds were recognised as distinct by smith, though a large number of deposits now known to belong to the last named were thrown in with other rocks as 'killas.' the devonian system was established and the name given to it in by sedgwick and murchison, largely owing to the palæontological researches of lonsdale. an attempt was subsequently made to abolish the system, but the detailed palæontological studies of r. etheridge finally placed it upon a secure basis. the establishment of the devonian system cleared the way for the right understanding of the lower palæozoic rocks, which sedgwick and murchison had commenced to study before the actual establishment of the devonian system, and to these workers belongs the credit of practically completing what was begun by william smith, namely, the establishment of the geological sequence of the british strata. the controversy which unfortunately marked the early years of the study of the british lower palæozoic rocks is well-nigh forgotten, and in the future the names of sedgwick and murchison will be handed down together, in the manner which is most fitting. our account of the growth of british stratigraphical geology is not yet complete. in , sir william logan applied the term laurentian to a group of rocks discovered in canada, which occurred beneath the lower palæozoic rocks. murchison shortly afterwards claimed certain rocks in n.w. scotland as being of generally similar age, and since then a number of geologists, most of whom are still living, have proved the occurrence of several large subdivisions of rocks in britain, each of which is of pre-palæozoic age. the above is a brief description of the growth of our knowledge of the order of succession of the strata which is the foundation of stratigraphical geology. a sketch of the manner in which the knowledge which has been obtained has been applied to the elucidation of the earth's history of different times would require far more space than can be devoted to it in a work like the present, but some idea of it may be gained from a study of the later chapters of the book. it will suffice here to remark, that to godwin-austen we owe the foundation of what may be termed the physical branch of palæo-physiography, which is concerned with the restoration of the physical conditions of past ages, while cuvier and darwin have exerted the most influence on the study of stratigraphical palæontology. chapter iii. nature of the stratified rocks. the present constituents of the earth which are accessible for direct study are divisible into three parts. the inner portion, consisting of _rocks_, is known as the _lithosphere_; outside this, with portions of the lithosphere projecting through into the outermost part, is the _hydrosphere_, comprising the ocean, lakes, rivers, and all masses of water which rest upon the lithosphere in a liquid condition. the outermost envelope, which is continuous and unbroken is the _atmosphere_, in a gaseous condition. it is well known that some of the constituents of any one of these parts may be abstracted from it, and become a component of either of the others; thus the atmosphere abstracts aqueous vapour from the hydrosphere, and the lithosphere takes up water from the hydrosphere, and carbonic anhydride from the atmosphere. the nebular hypothesis of kant and laplace necessitates the former existence of the present solid portions of the lithosphere in a molten condition, and accordingly the first formed solid covering of the lithosphere, if this hypothesis be true, must have been formed from molten material, or in the language of geology, it was an _igneous rock_. consequently, the earliest _sedimentary rock_ was necessarily derived directly from an igneous rock, with possible addition of material from the early hydrosphere and atmosphere, and all subsequently formed sedimentary rocks have therefore been derived from igneous rocks (with the additions above stated) either directly, or indirectly through the breaking up of other sedimentary rocks which were themselves derived directly or indirectly from igneous rocks. the observations of geologists show that this supposition that the materials of sediments have been directly or indirectly obtained for the most part from once-molten rocks is in accordance with the observed facts, and so far their observations testify to the truth of the nebular hypothesis. this being the case, the study of the petrology of the igneous rocks is necessary, in order to arrive at a true understanding of the composition of the sedimentary ones. the igneous rocks are largely composed of four groups of minerals, viz.--quartz, felspars, ferro-magnesian minerals, and ores. of these the quartz (composed of silica) yields particles of silica for the formation of sedimentary rocks; the felspars, which are double silicates of alumina and an alkali or alkaline earth, being prone to decomposition furnish silicate of alumina and compounds of soda, potash, lime, &c. the ferro-magnesian minerals (such as augite, hornblende and mica) may undergo a certain amount of decomposition, and yield compounds of iron, lime, &c. we may also have fragments of any of these minerals, and of the ore group in an unaltered condition. the composition of a sedimentary rock which has undergone no alteration after its formation will therefore depend upon the character of the rock from which it was derived, the chemical changes which take place in the materials which compose it, before they enter into its mass, and the mechanical sorting which they undergo prior to their deposition. in the above passage the terms igneous rock and sedimentary rock have been used, and it is necessary to give some account of the sense in which they were used. an _igneous_ rock is one which has been _consolidated_ from a state of _fusion_. it is not necessary to discuss here the exact significance of the word fusion, and whether certain rocks which are included in the igneous division were formed rather from solution at high temperature than from actual fusion. this point is of importance to the petrologist, but to the student of stratigraphical geology the term igneous rock may be used in its most comprehensive sense. these igneous rocks were consolidated either upon the surface of the lithosphere or in its interior. the other great group of rocks is one to which it is difficult to apply a satisfactory name. they have been termed by different writers, _sedimentary_, _stratified_, _derivative_, _aqueous_, and _clastic_, but no one of these terms is strictly accurate. the term _sedimentary_ implies that they have settled down, at the bottom of a sheet of water for instance. it can hardly be maintained that limestones formed by organic agency, like the limestones of coral reefs, are sedimentary in the strict sense of the term, and an accumulation like surface-soil can only be called a sediment by straining the term. _stratified_ rocks are those which are formed in strata or layers, but many of the rocks which we are considering do not show layers on a small scale, and igneous rocks (such as lava-flows) are also found in layers, though such layers are not true strata in the sense in which the term is used by geologists; the term _stratified_ is perhaps the least open to objection of any of those named above. _derivative_ implies that the fragments have been derived from some pre-existing rock, but as there are many ways in which fragments of one rock may be derived from another, the term is too comprehensive. _aqueous_ rocks should be formed in water, and most of the class of rocks which we are considering have been so formed, but others such as sand-dunes and surface-soil have not. (the term aerial or Æolian has been suggested to include these rocks which are thus separated from the aqueous rocks proper; the objection to this is that the origin of these rocks is closely connected with that of the true aqueous rocks, and moreover the group is too small to be raised to the dignity of a separate subdivision.) lastly, the name _clastic_ has been given, because the rocks so called are formed by the _breaking up_ of pre-existing rocks. there are two objections to this name. in the first place, some rocks included under the head clastic are formed by solution of material and its consolidation from a state of solution by chemical or organic agency, though we may perhaps speak of rocks being broken up by chemical as well as by mechanical action. the most important objection is that many clastic rocks are formed by the breaking up of rocks subsequently to their formation, and it has been proposed that rocks of this nature should be termed _cataclastic_, while those which are formed by the breaking up of pre-existing rocks upon the earth's surface should be termed _epiclastic_; another group formed of materials broken up within the earth, and accumulated upon its surface as the result of ejection of fragmental material from volcanic vents being termed _pyroclastic_. this classification is scientific, and under special circumstances is extremely useful, but the older terms have been used so generally, and with this explanation their use is so unobjectionable, that they may be retained, and the term _stratified_ will be generally used to indicate all rocks which are not of igneous origin or formed as mineral veins in the earth's interior. the division of rocks into _three_ great groups, the igneous, stratified and metamorphic (the latter name being applied to those rocks which have undergone considerable alteration since their formation), is objectionable, since we have metamorphic igneous rocks as well as metamorphic stratified ones. the most convenient classification is as follows:-- a. igneous . { unaltered. . { metamorphic. b. stratified . { unaltered. . { metamorphic. it must be distinctly understood that all geological phenomena must be taken into account by the stratigraphical geologist. the upheaval of strata, the production of jointing and cleavage in them, their intrusion by igneous material, their metamorphism, give indications of former physical conditions equally with the lithological characters of the strata, and their fossil contents. nevertheless it is not proposed to give a full account of the various phenomena displayed by rocks; the student is referred to text-books of general geology for this information. it will be as well here, however, to point out in a few words the exact significance of the existence of strata in the lithosphere. the formation of strata and their subsequent destruction to supply material for fresh strata are due to three great classes of changes. beginning with a portion of lithosphere composed of rock, it is found that rock is broken up by agents of denudation, as wind, rain, frost, rivers and sea. these agents perform their function mainly upon the portion of the lithosphere which projects through the hydrosphere to form _land_, and the land is the main area of denudation. the materials furnished by denudation are carried away, and owing to gravitation, naturally proceed from a higher to a lower level, often resting on the way, but if nothing else occurs, ultimately finding their way to the _sea_, where they are deposited as strata. the sea is the principal area for the reception of this material, and it is there accordingly that the bulk of stratified rock is formed. if nothing else occurred, in time the whole of the land would be destroyed, and the wreckage of the land deposited beneath the sea as stratified rock. as it is there is a third class of change, underground change, causing movements of the earth's crust (to use a term which can hardly be defined in few words but which is generally understood), and as the result of the relative uplift of portions of the earth's crust, the stratified rocks formed beneath the oceans are raised above its level, giving rise to new masses of land, which are once more ready for destruction by the agents of denudation. this cycle of change (all parts of which are ever proceeding simultaneously) is one of the utmost importance to the stratigraphical geologist. _stratification_ is the rock-structure of prime importance in stratigraphical geology, and a few words must here be devoted to its consideration, leaving further details to be dealt with hereafter. the surface of the ocean-floor is, when viewed on a large scale, so level, that it may be considered practically horizontal, and accordingly in most places the materials which are laid down on the ocean-floor give rise to accumulations which at all times have a general horizontal surface (when the ocean-slopes depart markedly from horizontality the deposits tend to abut against these slopes rather than to lie with their upper surfaces parallel to their original angle). a practically horizontal surface of this character may give rise to a _plane of stratification_ (or _bedding-plane_) in more than one way. a pause may occur during which there is a cessation of the supply of material, so that the material which has already been accumulated has sufficient time to become partially consolidated before the deposition of fresh material upon it. in this way a want of coherence between the two masses is produced, along the plane of junction, which after consolidation of the deposits causes an actual divisional plane along which the two deposits may be separated. this is a plane of stratification. the pause may be produced in various ways, sometimes between successive high tides, at others as the result of physical changes which may have taken ages to happen. again, after material of one kind has been deposited, say sand, some other substance such as clay may be accumulated on its upper surface, giving rise to a plane of stratification between two deposits of different lithological characters. if this occurs alone, there may be actual coherence between the two strata, so that it is erroneous to speak of a plane of stratification as if it were always one along which one deposit could be readily split from the other, though as a general though by no means universal rule, change from one kind of deposit to another is also marked by want of coherence between the two. the material between two planes of stratification forms a _stratum_ or _bed_, though if the deposit be very thin it is known as a _lamina_, and the planes are spoken of as _planes of lamination_ (no hard and fast line can be drawn between strata and laminæ; several of the latter usually occur in the space of an inch). a _stratum_ will have its upper and lower surface apparently parallel, though not really so, for no stratum extends universally round the earth, and many of them disappear at no great distance when traced in any direction. parts of one stratum may be composed of different materials from other parts when traced laterally, thus one stratum may be found composed essentially of sand in one place, of mud in another, and of a mixture of the two in an intervening locality. whatever be the composition of a stratum it dies out eventually, owing to the coming together of the upper and lower bounding planes of stratification. the stratum is thickest at some spot, from that spot it becomes thinner in all directions, until it disappears at last by the coalescence of the bounding-planes. this is spoken of as _thinning-out_. strata, then, consist of lenticular masses of rock, separated from the underlying and overlying strata by planes of stratification. the shape of the lenticle may vary immensely, the thickness bearing no definite relationship to the horizontal extent. some strata, many feet in thickness, may thin out and disappear completely in the course of a few yards, whilst others an inch or two in thickness may be traced horizontally for many miles. we often find thin strata of coal and limestone, extending for great distances, strata of mud thinning out more rapidly, and sandstones still more rapidly, but no universal rule connecting rapidity of thinning-out with composition of the strata can be laid down. having seen what a stratum is, it now remains to speak of the composition of the stratified rocks. they have been classified according to their composition, and according to their origin. according to composition they have been divided into: _arenaceous_ rocks, composed essentially of grains of sand. _argillaceous_ rocks, composed essentially of particles of mud. _calcareous_ rocks, composed essentially of particles of carbonate of lime. _carbonaceous_ rocks, composed largely of hydrocarbon compounds. _siliceous rocks_, composed essentially of silica not in the form of grains; whilst according to their origin they have been separated into:-- _mechanically-formed_ rocks, composed of fragments derived from other rocks by mechanical fracture. _chemically-formed_ rocks, composed of particles which have been chemically deposited from a state of solution. _organically-formed_ rocks, composed of materials which have been derived from a state of solution or from the gaseous condition by the agency of organisms. whichever classification be adopted (and each is useful for special purposes), it must be noted that no hard and fast line can be drawn between one division and another. a rock may be partly arenaceous and partly calcareous, composed of a mixture of sand and lime, and the same rock may similarly be partly mechanically and partly organically formed, the sand being due to mechanical fracture, and the lime to the agency of organisms, and so with the other divisions. as many of the changes which have occurred in past times have been concerned in destruction and obliteration, whilst deposition is the cause of preservation, the study of deposits is peculiarly adapted for testing the truth of the grand principle of geology that the changes which have taken place in past times are generally speaking similar in kind and in intensity of action to those which are in progress at the present day, and a study of the modern deposits is specially important as throwing light upon the characters of those which have been formed in past times. it will be abundantly shown in the sequel that the deposits of the strata are in general comparable in all essential respects with those which are being formed at present, and accordingly they give most valuable indications as to the nature of the physical and other conditions under which they were laid down. the desert sand, the precipitate of the inland sea, the reef-limestone and many another deposit can thus be detected by an examination of their lithological characters, combined with consideration of other kinds of evidence. the petrology of the sedimentary rocks is still in its infancy, though much has already been done, but it offers a wide field of inquiry to the field-geologist and worker with the microscope[ ]. [footnote : the student will do well to consult _the challenger report_ by messrs murray and renard ( ), for information concerning many modern sediments, and harker's _petrology for students_ section d, for general information on the petrology of the stratified rocks.] chapter iv. the law of superposition. in a previous chapter this law was given as follows: "of any two strata, the one which was originally the lower is the older;" the general truth of the law depends upon the fact that except under very exceptional circumstances the strata are deposited upon the surface of the lithosphere, and not beneath it. there are occasions where strata may be deposited beneath the lithosphere, but as a general rule the geologist will not be misled by such occurrences. in caverns, accumulations often occur which are newer than the strata over the cavern roof, and so long as caverns are formed in ordinary sedimentary rocks, no great difficulty will result from this exception to the law of superposition. when caverns occur beneath masses of land ice, the order of superposition may be misleading. a deposit may be formed on the surface of the ice, and subsequently to this a newer deposit may be laid down in a sub-glacial or englacial cavern; upon the melting of the ice the newer deposit would be found with the older one resting upon its surface. apart from these exceptional cases, the law as stated holds good, but the reader will notice the insertion of the word 'originally' which requires some comment. a geologist speaks of one bed lying _upon_ another not only when the beds are horizontal, but when they are inclined at any angle, until they become vertical, so that until beds have been turned through an angle of ° by earth-movement the test of superposition is applicable, but when they have been turned more than °, the stratum which was originally lower rests upon that which was originally above it, and in the case of these _inverted_ strata, the test of superposition is no longer applicable. it was formerly supposed that cases of inversion were comparatively rare and local, and that the test of superposition could therefore be generally applied with confidence, but it is now known that though this is generally true of such strata as have been subjected only to those widespread, fairly uniform movements which are spoken of as _epeirogenic_ or continent-forming, where the radius of each curve is very long, inversion is a frequent accompaniment of the more local _orogenic_ or mountain-forming movements, where the radius of a curve is short. though orogenic movements are limited as compared with those of epeirogenic character, they often affect large tracts of country, in which case the apparent order of succession of the strata need not be the true one, and examples of inversion may be frequent[ ]. [footnote : for a discussion of the principles of mountain-building see heim, a., _untersuchungen über den mechanismus der gebirgsbildung_, and lapworth, c. "the secret of the highlands," _geological magazine_, decade ii. vol. x. pp. , , .] it is not easy to lay down any definite rules for detecting inverted strata, where the top of an inverted arch is swept off by denudation or the bottom of an inverted trough concealed beneath the surface, beyond stating that if an easily recognised set of beds is obviously repeated in inverse order, inversion must have occurred, though even then it may not be clear which side of the fold shows the beds in original and which in inverted sequence. suggestions are frequently made that ripple-marks and worm-tracks may be utilised in order to discover inversion, for the well-formed ripple-marks will appear convex on the upper surface of a bed which is not inverted, and we may note concave casts of these ripple-marks on the under surface of the overlying bed, whilst worm-tracks will appear concave on the upper surface, and their casts convex on the lower surface of the succeeding bed under similar conditions. in the case of inversion the occurrences will be the exact opposite to these. unfortunately ripple-marks and worm-tracks may, as will appear in the sequel, be simulated by structures produced in quite a different way, and unless the observer is certain that he is confronted with true ripple-marks and worm-tracks he may be seriously misled. the geologist must take into account all the evidence at his disposal, when he is dealing with cases of possible inversion, but oftentimes he will after due consideration of all the phenomena be left in doubt unless he is able to supplement his observations on the succession of the strata by evidence derived from the included fossils. the test of superposition is most apt to be misleading when the strata have been affected by the faults known as reversed faults or thrust-planes. reference to text-books will show that a fold consists of two parts, the arch and the trough, and that the two are connected by a common-, middle-, or partition-limb. in the case of an inverted fold, an =s=-shaped or sigmoidal structure is the result (fig. a). [illustration: fig. . a. a sigmoidal fold, showing a bed _xx_ in an overfold with arch (_a_), trough (_t_) and common limb _c_. b. a similar bed _xx_ affected by a thrust-plane _tt_ which replaces the common limb.] here the portions of any bed (_xx_) which occur in the arch or trough are in normal position, and have not been moved round through an angle of °, whilst the portion which occurs in the common limb c has been moved round through an angle greater than ° and is inverted, so that its former upper surface now faces downwards. in fig. b the common limb is replaced by a reversed fault, or thrust-plane, and the inverted portion of the bed seen in the common limb is therefore absent. an observer, applying the test of superposition, might suppose that the position of the bed _x_ on the left-hand side of the figure was a different bed from the portion which is seen on the right-hand side, instead of belonging to the same bed, and in this way, if a number of parallel thrust-planes affected one bed or a set of beds, he might be led to infer the occurrence of a great thickness of strata where there was in reality a slight thickness, or even one bed only repeated again and again by faulting. it is quite certain that exaggerated estimates of the thickness of deposits have frequently been made owing to the non-recognition of the occurrence of repetition as a consequence of the existence of thrust-planes. where thrust-planes are suspected, it is well to look for some of the following features: (_a_) the strata of a country affected by thrust-planes often crop out as lenticular masses, thinning out rapidly in the direction of the strike[ ]. this is true of beds thrown into sharp folds whether or not inverted, but the lenticles will be wider in a direction at right angles to that of the strike as compared with their length when inversion has not occurred. it is also true of beds which were originally deposited as lenticles, such as many massive sandstones, and as almost any kind of deposit may be formed originally as a lenticle, the test by itself is by no means sufficient as a proof of thrusting, though it is suggestive. [footnote : for definitions of the terms dip, strike, outcrop and allied expressions, the reader is referred to a _text-book of geology_.] (_b_) the _surfaces_ of the strata are often affected by the striations known as slickensides, and the joint-faces of gently inclined beds are also frequently marked by slickensides which often run in a nearly horizontal direction. (_c_) a parallel structure presenting the appearances characteristic of the mechanically-formed features of a foliated rock is often developed, and one or more of certain accompanying phenomena will probably be found, which will be noticed more fully in a later chapter. (_d_) extension or stretching of the rocks will have been frequently produced, causing rupture, and the resulting fissures are usually filled with mineral-veins, though this occurrence is by no means characteristic of rocks which have been affected by thrust-planes. (_e_) chemical changes may have occurred which have resulted in the reconstitution of some of the rock-constituents, which may crystallise where pressure is least, thus we often find rocks which have undergone movements of the type we are considering marked by the existence of sericitic films upon the surfaces. another reservation must be made when considering the law of superposition. the test is only applicable for limited areas. suppose we find a deposit of clay _a_ resting upon another deposit of limestone _b_ in the south of england, and can prove that the apparent succession is the true one, that is, that there has been no inversion; it is clear that the test of superposition is applicable in that area. now, we may be able to trace the two deposits continuously across the country, one as a clay, the other as a limestone; so that when we reach the north of england we find the clay _a_ still reposing upon the limestone _b_. the test of superposition is applicable in that area also, the clay of the northern area being newer than the limestone of the same region. but, for reasons which will ultimately appear, it by no means follows that the clay of the north is newer than the limestone of the south, although the two deposits are continuously traceable with the same lithological characters; it may have been formed simultaneously with the limestone of the south, or even before it. something more, therefore, than the test of superposition is necessary in order to make out the relative ages of continuous deposits in a wide region, and this is still truer in the case of deposits which are discontinuous, whether separated from one another by the sea, or by outcrops of older or newer rocks. a few words of warning may be added with reference to the detection of bedding-planes. a bedding-plane is one which separates two beds, and its existence is determined during the deposition of the beds. many other planes are formed in rocks subsequently to their deposition, and it is not always easy to distinguish these from true bedding-planes. that even experienced observers may be led astray is shown by the fact that, of recent years, it has been proved that great masses of rock have been claimed as of sedimentary origin, and their apparent order of succession noted, which are in truth naught but irregular masses of intrusive igneous rocks affected by divisional planes which simulate bedding, produced in the rocks subsequently to their consolidation. joints, faults, and cleavage-planes may all at times simulate planes of bedding, and it is frequently very difficult to distinguish them in the limited exposures with which a geologist has oftentimes to deal. it is easier to make suggestions for distinguishing bedding-planes from other planes which simulate them, than to apply the suggestions in practice, and the student of field geology will find that experience is the only guide, though after years of experience he may be confronted with cases where the evidence is insufficient to convince him that he is dealing with planes of stratification and not with some other structure. from what has been remarked, it will be inferred that the test of superposition though of prime importance to the geologist is frequently insufficient to enable him to ascertain the true order of succession of the strata, and he is compelled to supplement this test by some other. there are several useful physical tests which may frequently be applied. thus, if a rock _a_ contains fragments of another rock _b_, _under such circumstances as to show that the fragments of_ b _were included in a during its deposition_, it is clear that _b_ is older than _a_. here again, it will be found from what appears in a later chapter that the student is confronted with difficulties when actually examining rocks, for fragmental rocks of cataclastic origin, where the fragments have been formed as the result of fracture produced by earth-movements subsequently to the deposition of the rock, simulate epiclastic rocks in which the fragments were introduced during the accumulation of the deposits to so surprising a degree as sometimes to baffle the most experienced observer. not only are the fragments of these cataclastic rocks broken up, but they may be further rounded so as to imitate in a remarkable manner the water-worn pebbles of an epiclastic conglomerate. again, an older series of rocks may have had structures impressed upon them as the result of changes subsequent to their formation, and before the formation of a newer set which the latter therefore do not exhibit. jointing, cleavage, and various metamorphic phenomena may thus be exhibited by the older rocks, but great care is required in applying this test, especially with a limited thickness of rocks, as one set may not exhibit the structures not because they were not in existence when the structures were developed, but because their nature is such that they were incapable of receiving or retaining the structures. for instance a mass of grit which is older than a mass of clay-slate may not be cleaved, because, although subjected to the pressure which produced the cleavage, it was of a nature not adapted to the development of cleavage structure. on the whole, application of tests dependent upon physical features of rocks, does not often supplement to any great extent the information supplied by ascertaining the order of superposition, and in all cases, where possible, every other kind of information should be supplemented, by that which is acquired after examination of the included organisms of the strata. chapter v. the test of included organisms. the second great law of the stratigraphical geologist is that fossiliferous strata are identifiable by their included organisms, in other words, that we can tell the geological age of deposits by examination of the fossils contained in them, though the determination of age must be given in more general terms in some cases than in others. considerable misconception has arisen concerning the value of fossils as indices of age, and it is necessary therefore to discuss the significance of the law of identification of strata by their included organisms at some length. the comparison between fossils and medals has frequently been made and fossils have well been styled the "medals of creation"; and the significance of fossils as guides to the age of deposits may perhaps be made clearer if we pursue this comparison some way. in the first place there is clear indication of a gradual increase in the complexity of organisation of the fossils as one passes from the earlier to the later rocks, and accordingly the general facies of a fauna is likely to furnish a clue to the age of the rocks in which it is found, even though every species or even genus represented in the fauna was previously unknown to science. so an antiquary versed in the evolution of art or metallurgy, might detect the general age of a medal with whose image and superscription he was not acquainted. he would know that a medal struck in iron was formed subsequently to the bronze age, or that one formed of palladium appertained to the present century. but quite apart from any theoretical knowledge, an antiquary would find as the result of accumulated experience that certain medals are characteristic of certain periods; he would learn that the denarius is characteristic of a different period from that indicated by the coin of the victorian era, even though he had no knowledge of the technicalities of numismatics. the same is the case with the geologist. he may not be influenced by any knowledge of the evolution of faunas and floras, but actual work amongst the rocks will show him that the trilobite is not found with the belemnite or the ichthyosaur with the elephant, save under exceptional circumstances, which only prove the rule, as for instance when worn bones of ichthyosaurs are washed from their proper strata into gravels with elephant-bones. it must be distinctly understood that the determination of fossils as characteristic of different periods is solely made as the result of experience. no _à priori_ reasoning may give one indication of the actual range in time of a species or genus; no one can say why _discina_ has a long range in time, whilst that of the closely related _trematis_ is very limited. this being the case, the greater the mass of evidence which is accumulated as to the range of a fossil, the greater will be the value of that fossil as a clue to the age of the deposit in which it is found. this is so important, that it requires more than mere notice. if a fossil is found in abundance in a group of strata _b_ in any one area, and is not found in an underlying group _a_ or overlying group _c_ in that area after prolonged search, we may confidently speak of the fossil as characteristic of the strata _b_ in that area, though without further work, the value of the fossil as a clue to age in other areas would be unproved. it may nevertheless happen, that after more prolonged search in _a_ or _c_, in the original area a few specimens of the fossil which has been spoken of as characteristic of _b_ may be found in one or other of them, in small quantity. the value of the fossil as one characteristic of _b_ will be slightly diminished, though only slightly, as it is not likely to turn up in numbers in the strata _a_ or _c_ after the prolonged search. should the fossil be found also to be characteristic of the strata _b_ in areas other than the original one, it becomes of more than local value, and if, after much study it is found to characterise the same strata over wide areas, the cumulative evidence now obtained will render the fossil peculiarly important to the stratigraphical geologist. the detection of characteristic fossils is not quite so simple as might be supposed from the above remarks, for examination of the position of one fossil will not prove the contemporaneity of beds in different places, to prove this, all the evidence at our disposal must be considered, for reasons which will be presently pointed out. as the result of accumulated knowledge, we can now compile lists of characteristic fossils of the major subdivisions of the strata, which are of world-wide utility and as our knowledge increases, we are enabled to subdivide the strata into minor divisions of more than local value. _what is a fossil?_ before discussing the value of fossils as aids to the stratigraphical geologist, it may be well to make a few observations as to what constitutes a fossil. it is difficult to give any concise definition, and as is often the case in geology, an explanatory paragraph is of more value than a mere definition. the term fossil was originally applied to anything dug up from the rocks of the earth's crust, and was used with reference to inorganic objects as well as organic remains, for instance minerals were spoken of as fossils. it is now applied essentially though not exclusively to relics of former organisms, though one still reads of fossil rain-drops, fossil sun-cracks, and so on. furthermore, the relics need not necessarily be parts of the organism, the track of a worm or a bird's nest if embedded in the strata would be termed a fossil. it is generally agreed that no sharp line can be drawn between recent and fossil organic remains which is based upon the degree of mineralisation (or as it was sometimes termed petrifaction) of the relics, for many true fossils have not undergone mineralisation, subsequent to their entombment. it has been suggested that the name fossil should be applied to organic remains which have been entombed by some process other than human agency, but this restriction is undesirable. the stone-implement of the river gravels is as genuine a fossil as the ammonite extracted from the chalk, and the human relics of very recent date may give information of a character quite similar to that supplied by other remains, for instance, the occurrence of moa-bones in new zealand in accumulations below those containing biscuit-tins and jam-pots has been used as a geological argument pointing to the extinction of the moa before the arrival of europeans in new zealand. the biscuit-tin here serves all the purposes of a fossil, and there is no valid reason why it should not be spoken of as such. this statement brings one to consider another method which has been adopted in order to separate fossil organisms from recent ones, namely the time-test. this again is inapplicable, for no line can be drawn between the shell which was buried in yesterday's tidal deposit and that which has lain in the strata through geological ages, and each may be equally useful to the geologist. whilst, then, we can give no definition of fossil which is likely to meet with general acceptance, the term can be so used, as not to give rise to any doubts as to its meaning, and it is generally applicable to any organic relics which have been embedded in any deposit or accumulation by any agent human or otherwise. _mode of occurrence of fossils._ it will not be out of place to say a few words as to the way in which fossils are found in strata, as beds are often inferred to be unfossiliferous, because of ignorance of methods which should be pursued in searching for organic relics. it is unnecessary to dilate upon the actual modes of preservation of organisms, which is treated of fully in other works. in the first place, it is rash to assert that any deposit is unfossiliferous because no fossils have been found in it, even after prolonged search. the llanberis slates had been eagerly searched for fossils for many years without result, but that the search was not exhaustive was proved by the discovery of trilobites in them some years ago. seekers after fossils are rather prone to confine their attention to strata which are already known to be fossiliferous than to pay much attention to those which have hitherto yielded no organic remains. some kinds of deposits are more often fossiliferous than others. limestones which are frequently largely of organic origin, are often rich in remains, and muddy deposits more frequently furnish fossils than those of a purely sandy nature. the difference in the yield is not necessarily due to the original inclusion of more remains in one rock than in another, but is often caused by the obliteration of former relics owing to changes which have taken place in the rocks subsequently to their deposition. no sedimentary rock must be regarded as unfossiliferous, however unfitted it appears for the preservation of fossils. the writer has seen fossils, not only in coarse conglomerates, rocks which frequently contain no traces of organisms, but in deposits composed largely of specular iron ore, and even in intrusive igneous rocks, though in the latter case, the inclusion of fossils was due to circumstances which cannot have occurred with frequency. in sandy strata, the substance of the fossils has often been completely removed, leaving hollow casts, which may be almost or quite unrecognisable. in these circumstances, much information may be obtained by taking impressions of the casts in modelling wax or some other material. the importance of this process may be judged from the results it yielded to mr clement reid in the case of the fossils of the pliocene deposits occurring in pipe-like hollows in the cretaceous rocks of kent and the discovery of the remarkable reptiles described by mr e. t. newton from the triassic sandstones of elgin. in argillaceous rocks which have been affected by the processes producing cleavage, the fossils may be distorted beyond recognition or owing to the difficulty of breaking the rocks along the original planes of deposition, may remain invisible. under such circumstances, small nodules of sandy or calcareous nature may sometimes be found included in the argillaceous deposits and may perhaps yield fossils. oftentimes, also, where the argillaceous rock is in close proximity to a harder rock, such as massive grit, the argillaceous rock in close contiguity to the hard rock may escape the impress of cleavage-structure, and fossils may be readily extracted from rocks in this position when not obtainable from other parts of the deposit. it was under these circumstances that the trilobites alluded to above were obtained from the llanberis slates. the fossils of calcareous rocks are often very obvious, but difficult to extract, as they break across when the rock is fractured. they are frequently obtainable in a perfect condition when the rock is weathered. occasionally they may be extracted from certain argillaceous limestones if the limestone be heated to redness, and suddenly plunged into cold water. fossils are often found in a state which enables them to be readily extracted when a limestone is coarsely crystalline, though they cannot be extracted in a perfect condition when the same limestone is in a different state. many microzoa, which are invisible in rocks, even when viewed through a lens, may be found in microscopic sections of calcareous and silicious rocks, and plant structures may be detected under similar circumstances in the case of carbonaceous rocks. various special methods of extracting fossils from rocks have been described by different writers, many of which are very complex, and require much time. the mechanical action of the sand-blast and the solvent action of various acids as hydrochloric and hydrofluosilicic have been found of use upon different occasions[ ]. the various processes which have been utilised in order to extract and develop fossils can, however, be best learned by information obtainable from curators of palæontological collections, and by actual experience, and there is yet much information to be acquired as to the manner of extracting fossils from various kinds of rocks. [footnote : for information concerning use of acids see especially wiman, c. "ueber die graptoliten," _bull. geol. inst._, upsala, no. , vol. ii. part ii.] _relative value of fossils to the stratigraphical geologist._ it has been hinted above that no general rule as to the relative value of fossils as guides to the age of strata can be laid down, and that the ascertainment of their relative value is largely the result of actual experience. it may be noted, however, that organisms which possess hard parts are naturally more important to the geologist than those which do not, as few traces of the latter are preserved in the fossil state, and even when preserved are usually too obscure to be of much practical use. of the organisms which do possess hard parts, different groups have been utilised to a different degree, and one group will be more or less important than another, according to the use to which it is applied. groups of organisms which have a long range in time are naturally useful for the identification of large subdivisions of the strata, whilst those which have had a shorter range are valuable when separating minor subdivisions. again, as the bulk of the sedimentary deposits has been formed beneath the waters of the ocean, relics of marine organisms are naturally more useful than those of freshwater ones. other things being equal, the more easily the organism is recognisable, and the more abundant are its remains, the greater its value to the stratigraphical geologist, and as the remains of invertebrates are usually found in greater quantities and in more readily recognisable condition than those of the vertebrates, they have been used more extensively as indices of age. of the invertebrates, the mollusca are often very abundant, their remains are adapted for preservation, and their characteristics have been extensively studied, and accordingly they have been and are of great use to the geologist. of other groups, the graptolites, corals, echinids, brachiopods, and trilobites have been very largely utilised. the lower palæozoic strata have been divided into numerous groups, each characterised by definite forms of graptolites, and a similar use has been made of the ammonites in the case of the mesozoic rocks. it is not to be inferred that these groups of organisms are naturally more useful than other groups, on account of the extent to which they have been used; we can merely state that they have been proved to be useful as the result of prolonged study; when other groups have received equal attention, they may well be found to be equally useful for the purposes which we have in view. _contemporaneity and homotaxis._ from what has been already stated, it will be recognised that the ages of the various fossiliferous rocks of the geological column[ ] in any one area can be identified with greater or less degree of certainty by reference to their included organisms, the various subdivisions being marked by the possession of characteristic fossils, and it will be naturally and rightly inferred that the greater the number of characteristic fossils of any one deposit, the more certain is the identification of that deposit. in practice, geologists are wont to ascertain the age of the strata after consideration of all the fossils found therein, some of which may be actually characteristic whilst many may come up from the strata below, or pass into those above. having ascertained the order of succession and fossil contents of the strata in various regions, it is the task of the geologist to compare the strata of these two regions, and this task is fraught with considerable difficulty. much controversy has arisen as to the degree of accuracy with which strata of remote regions can be correlated, and the subject is one which requires full consideration. [footnote : although the rocks do not always lie on one another in regular succession, it is often convenient to speak of them as though they did, and as though a column of strata could be carved out in any region consisting of horizontal bands of deposit one above another. we speak of such an ideal arrangement as constituting a 'geological column.'] suppose that a series of strata which we will call _a_, _b_, and _c_ is found in any one area, each member of which contains characteristic fossils which enable it to be recognised in that area, and we will further suppose that in another area a series of strata _a´_, _b´_, and _c´_ is discovered, of which _a´_ has the fauna of _a_ in the former area, and similarly _b´_ the fauna of _b_, and _c´_ that of _c_. it cannot be assumed that the stratum _a_ is therefore contemporaneous with _a´_, _b_ with _b´_, and _c_ with _c´_, but on the other hand, it must not be assumed that they are not contemporaneous. this is a statement which requires some comment. it has been urged that if the deposits _a_ and _a´_ in different localities contain the same fauna, this is a proof that the two are not contemporaneous, for some time must have elapsed in order to allow of the migration of the organisms from one area to another, it being justifiably assumed that they did not originate simultaneously in the two areas. but everything depends on the time taken for migration as compared with the period of existence of the fauna. if the former was extremely short as compared with the latter it may be practically ignored, for we might then speak of the strata as contemporaneous, just as a historian would rightly speak of events in the same way which occurred upon the same afternoon, though one might have happened an hour before the other. let us then glance at the evidence which we have at our disposal, which bears upon this matter. the objection to identification of strata with similar faunas as contemporaneous was urged by whewell, herbert spencer, and huxley, and the latter suggested the term homotaxis or similarity of arrangement as applicable to groups of strata in different areas, in which a similar succession of faunas was traceable, maintaining that though not contemporaneous the strata might be spoken of as homotaxial. huxley went so far as to assert that "for anything that geology or palæontology are able to show to the contrary, a devonian fauna and flora in the british islands may have been contemporaneous with silurian life in north america, and with a carboniferous fauna and flora in africa[ ]," a statement which few if any living geologists will endorse. if the statement be true, and the fauna which we speak of as devonian, when present be always found (as it is) above that which we in britain know as silurian and below that which we term carboniferous, the faunas must have originated independently in the three centres, and disappeared before the appearance of the next fauna, or having originated at the same centre, each must have migrated in the same direction, spread over the world, and become extinct as it reached the point or line from which it started. suppose for instance a fauna _a_ originates at the meridian of greenwich, migrates eastward, and dies out again when it once more reaches greenwich, that _b_ and _c_ do the same, at a later period, then the fauna _b_ will always be found above _a_ and _c_ above _b_, but if _b_ did not become extinct when it reached the greenwich meridian, it would continue its eastward course, and _c_ having in the meantime started on its first round, the fossils of the fauna _b_ would be found both above and below those of _c_. it will be shown below that cases of recurrence do occur, but nowhere do we find a silurian fauna above a devonian one, or a devonian one above one belonging to the carboniferous, nor is the fauna of a great group of rocks found in one region above the fauna of another group, and in another region below the same. and this is true not only of the faunas of one major division, such as those of the silurian and carboniferous periods, but also of the faunas of many minor subdivisions into which the large ones are separated, for instance we do not find the llandovery fauna of the silurian period which in britain is found below the wenlock fauna embedded elsewhere in strata above the wenlock. i have simplified the statement by assuming that the faunas are identical in the different localities, and exactly similar throughout the whole thickness of the containing strata, which is naturally not the case, but the additional complexity does not conceal the truth of what has been stated. in the absence of actual inversion of well-marked faunas, only one explanation is possible, namely, that the time for migration of forms is so short as compared with the entire period during which the forms existed, that it may be practically ignored, and the strata containing similar faunas may be therefore spoken of truthfully as contemporaneous and not merely homotaxial[ ]. [footnote : huxley, t. h. "geological contemporaneity and persistent types of life," being the anniversary address to the geological society for ; reprinted in _lay sermons, addresses and reviews_.] [footnote : for fuller discussion of this matter see a paper by the author 'on homotaxis,' _proc. camb. phil. soc._, vol. vi. part ii. p. .] _apparent anomalies in the distribution of fossils._ there are several occurrences which have tended to augment the distrust frequently felt concerning the value of fossils as indices of the age of the beds in which they occur, which may be here considered. though the greater number of fossil remains belonged to organisms which lived during the time of accumulation of the deposits in which they are now embedded, this is by no means universally the case, and the occurrence of _remanié_ fossils, which have been derived from deposits more ancient than the ones in which they are now found is far from being a rare event. the existence of remains of this nature in the superficial drifts and river-gravels of our own country has long been recognised, and no one would suppose that the _gryphæa_ and other shells furnished by these gravels had lived contemporaneously with the species of _corbicula_, _unio_ and other molluscs which are part of the true fauna of the gravels. in this case the water-worn nature of the remains is a good index to their origin, but in other cases, it is by no means an infallible guide, for we sometimes find on the one hand that remains of organisms proper to the deposits in which they occur are water-worn, whilst on the other the relics of _remanié_ fossils are not. the now well-known gault fossils of the cambridge greensand at the base of the chalk were not always recognised as having been derived from older beds, and there are certain fossils found in nodules in the cretaceous rocks of lincolnshire, which still form a subject for difference of opinion, for while some writers maintain that they belong to the deposits in which they are now found, others suppose that the nodules have been washed out of earlier beds. occasionally we find forms which occurring in a set of beds _a_ in an area, are absent from the overlying beds _b_, and appear again in the succeeding deposits _c_. such cases of _recurrence_ are by no means rare, though many supposed instances of recurrence have been recorded as the result of stratigraphical or palæontological errors. the best examples have been noted by barrande among the lower palæozoic deposits of bohemia. the stage _d_ of bohemia consists of five 'bandes' or subdivisions, the lowest (_d_ ), central (_d_ ) and uppermost (_d_ ) divisions are mainly argillaceous, whilst the second (_d_ ) and fourth (_d_ ) are essentially arenaceous. some of the forms found in _d_ , _d_ and _d_ have not been found in _d_ and _d_ . the best-known example is the trilobite _Æglina rediviva_. it is clear that this and other forms did not become extinct during the deposition of the strata of _d_ and _d_ , though they may have disappeared temporarily from the bohemian area, or else lingered on in such diminished numbers that their remains have not been discovered. the range of the organism is in fact right through the deposits of the stage _d_, and the discontinuity of distribution is not a real anomaly; it may be compared to some extent with cases of discontinuous distribution in space. it is needless to remark that the whole fauna does not disappear for a time and then reappear, but only a few out of the many forms which compose it. the comparative rarity of examples of recurrence after long intervals is an indication that the palæontological record as it is termed is not so imperfect as some suppose, for if our knowledge of fossils were very imperfect, we should expect cases of apparent recurrence to be common, as the result of the non-detection of fossils in the intermediate beds. one of the most marked cases of apparent recurrence known some years ago was the reappearance of a genus of trilobite _ampyx_ in ludlow rocks, found in the bala rocks, but not in the llandovery or wenlock strata. it has since been discovered in llandovery beds, and its eventual discovery in beds of wenlock age may be regarded as certain. a supposed case of recurrence which would have been remarkable, that of the disappearance of _phillipsia_ in ordovician rocks, its entire absence in those of silurian age, and its reappearance in the devonian, has broken down, for the supposed ordovician form has been shown to belong to an entirely different group of trilobites from that containing the genus _phillipsia_, and it has been therefore renamed _phillipsinella_. many apparent anomalies of distribution have been explained as due to migration, but it is doubtful whether any one of these supposed anomalies is actual and not due to errors in determining the position of the beds or the nature of their included fossils. some of the supposed anomalies have already been shown to be due to error, and the others will almost certainly be cleared up. in speaking of anomalies of distribution, the geologist can only be guided by experience as to what constitutes an anomaly. for instance the existence of a complete fauna in any one place in the beds of a system above that to which it is elsewhere confined would be regarded as anomalous and as probably due to error, whilst the reappearance of several forms in beds of a system higher than that in which they had hitherto been found, could hardly be considered as an anomaly. a geologist would suspect the statement that after the disappearance of an ordovician fauna in an area and its replacement by a silurian fauna, the ordovician fauna reappeared for a time, but would not regard the statement that a cenomanian fauna partly reappeared in the chalk rock with surprise. the existence of a silurian fauna in ordovician times was maintained by barrande in the case of the bohemian basin. lenticular patches of silurian rocks having the lithological characters of the silurian strata are found in the ordovician beds of that region, and they contain fossils specifically identical with those of the silurian rocks. barrande explained this appearance as due to the existence of a fauna in other regions resembling the silurian fauna of bohemia, during the ordovician period, when the normal ordovician fauna of bohemia inhabited that area. he supposed that in parts of the basin, when favourable conditions arose, _colonies_ of the foreign fauna settled for a time, but did not get a permanent footing in the basin until the commencement of silurian times. the theory of colonies has now been rejected for the bohemian area, and the phenomena shown to be due to repetition of strata by folding and faulting, but it is a theory which is again and again advocated in order to explain apparently anomalous phenomena in other areas, and these apparent anomalies which are so explained, must be regarded with grave suspicion. the various complexities alluded to in the foregoing pages increase the difficulty experienced by the geologist in correlating strata in different areas by their included organisms, but no one of them disproves the possibility of making these correlations, which can be carried on to a greater or less extent according to the nature of the faunas. a good deal of misconception has arisen concerning the geographical distribution of former faunas, owing to the tendency to compare them exclusively with the littoral faunas of the present day. these littoral faunas have a comparatively limited geographical distribution, the forms of one marine province often differing considerably from those of an adjoining one, and still more widely from one which is remote, so that anyone confronted with the relics of faunas from the existing australian and european seas, would find no indications furnished by identity of species that the faunas were contemporaneous. recent researches have shown, however, that the creatures whose remains are deposited at some distance from the coast-line have a much stronger resemblance to one another than the littoral organisms have, if the fauna of two distant areas be compared. it is still a moot point which will be discussed in a later chapter, how far the deep-sea deposits of modern times are represented amongst the strata of the geological column by deposits of similar origin. but it is certain that many of the ancient strata are not littoral deposits, and it will be found that it is by comparison of the faunas of the deeper-water deposits that the geologist correlates the strata of remote regions: where shallow water deposits are formed, the faunas differ markedly in different regions, and these shallow-water forms can only be correlated owing to their occurrence between deeper-water strata. thus if strata _a_, _b_ and _c_ be found in one area, and the fauna of _a_ and _c_ are deep-water forms, those of _b_ being shallow-water forms, and in another area beds _a´_ contain the same fauna as _a_, and _c´_ the same fauna as _c_ whilst the fauna of _b´_ is different from that of _b_, we can nevertheless correlate the strata _b_ and _b´_ (if they be conformable with the underlying and overlying beds), because of the identity of age of the associated beds in the two areas. it will possibly be found that the strata _a_ and _c_ can be further subdivided into _a_{ }_, _a_{ }_, ... &c. _c_{ }_, _c_{ }_, ... by the existence of minor faunas, which are comparable in the two cases, but such subdivisions may not be established in the case of the beds _b_ and _b´_. to take actual examples:--the llandovery beds of dumfriesshire can be subdivided into several minor divisions each of which can be recognised in the lake district of england, and to a large extent in scandinavia and elsewhere, for the deposits in these areas are of deep-water character, and the sub-faunas of the subdivisions are similar in the different areas, but the llandovery rocks of the welsh borderland are shallow-water deposits, with a different fauna from that of the deep-water deposits of this age, and can only be stated to be contemporaneous with the llandovery rocks elsewhere, because the deeper-water faunas of the underlying bala rocks and overlying wenlock rocks of the welsh borders are respectively similar to those of the bala and wenlock rocks of the other regions. the shallow-water llandoveries of the welsh borders have only been separated into two divisions, upper and lower, and have not been split up into a number of subdivisions, each characterised by a sub-fauna, and each comparable with one of the subdivisions of dumfriesshire, lakeland and the other regions where the deep-water facies is found. it will be seen that though the principle of william smith that strata can be recognised by their included organisms has been extended since his time, and shown to apply to far smaller subdivisions of the strata than was suspected, the method of application is the same, and is more or less successful according to the amount of evidence which is accumulated in support of it. chapter vi. methods of classification of the strata. earth-history like human history is the record of an unbroken chain of events. the agents which have produced geological phenomena have been in operation since the earth came into existence. accordingly a perfect earth-history would be written as a continuous narrative, just as would a complete history of the human race. the historian of man finds it not only convenient but necessary to divide the epoch of which he is writing into periods of time, and so does the geologist, and in each case the division is necessarily more or less arbitrary. it is true that in writing the history or geology of a country, marked events stand out which form a convenient means of making divisions, but the marked events occurring in one country are not likely to take place simultaneously with those of another country, and consequently a classification of this character is only locally applicable. the classification which is at present used by geologists was originally founded upon definite principles, and although our principles of classification have, as will appear, been somewhat altered subsequently, it has been found more convenient to modify the original classification than to adopt a new one in its entirety. the largest divisions into which the strata of the geological column were separated were instituted because of the supposed extinction of faunas, and sudden or rapid replacement by other faunas of an entirely different character. this supposed rapid extinction and replacement is now known to have been only apparent and due to observation in restricted areas, and it is doubtful whether the three great divisions founded upon them are not rather mischievous than useful, as tending to disseminate wrong notions. moreover there is considerable diversity of opinion as to the terms to be adopted. the rocks were formerly divided into primary, secondary, and tertiary. owing chiefly to the use of the term primary in another sense, the alternative titles palæozoic, mesozoic and cainozoic (or cænozoic) were suggested, and though the term primary has been definitely abandoned in favour of palæozoic, the words secondary and tertiary are used extensively as synonyms of mesozoic and cainozoic. it was soon perceived that the period of time included in the palæozoic age was much longer than the combined periods of secondary and tertiary ages, and it was proposed to group the latter under one title neozoic, whilst another suggestion was to split the palæozoic age into an earlier proterozoic and later deuterozoic division. the interest excited by the advent of man is probably the cause of the attempt to establish a quaternary division, which some hold to be a minor subdivision of the tertiary, whilst others would separate it altogether. the terms palæozoic, mesozoic (or secondary) and cainozoic (or tertiary) are now used so generally that any attempt to abolish them would be doomed to failure, but it must be remembered that they are purely arbitrary expressions, and the other terms which are not in general use, might be dropped with advantage. the other subdivisions have been used somewhat loosely, and although an attempt has been made by the international geological congress to restrict certain names to subdivisions of varying degrees of value, it will probably be found best to allow of a certain elasticity in the use of terms, merely agreeing that they shall be used as nearly as possible with the signification assigned to them by the congress. according to this classification, and apart from the division into palæozoic, mesozoic and cainozoic, the strata of the geological column are grouped into _systems_, which are subdivided into _series_, and the series are further split up into _stages_. a number of chronological terms were also suggested, of equivalent importance, thus the beds of a _system_ would be deposited during a _period_, those of a _series_ during an _epoch_, and those of a _stage_ during an _age_[ ]. [footnote : the chronological words have been used so loosely that it is doubtful whether any good will come of trying to restrict their use, and sir a. geikie has pointed out the confusion which would arise if the term _group_ be employed for the largest divisions (palæozoic, &c.). the terms _system_, _series_ and _stage_ may well be employed in the senses suggested by the congress.] the rocks of the geological column were originally divided into systems, owing to the occurrence of marked physical and palæontological breaks between the rocks of two adjacent systems, except in cases where a complete change occurred locally in the lithological characters of the rocks of two systems which were in juxtaposition: it is necessary to consider for awhile the nature of these breaks. the most apparent physical break is where the rocks of one set of deposits rest unconformably upon the rocks of another one, indicating that the older set has been uplifted and to some extent eroded before the deposition of the strata of the newer set. this uplift and erosion signifies a change from oceanic to continental conditions in the area in which unconformity is found on a large scale, and accordingly a long period of time would elapse during which the continental surface would not receive deposits, so that the highest rocks of the underlying system would be considerably older than the lowest rocks of the one which succeeds it. such a break may be obviously utilised for purposes of classification, but as some areas of the earth's surface must have been occupied by the waters of the ocean when other regions formed land, deposit in some areas must constantly have occurred simultaneously with denudation in others, and any classification founded upon the existence of unconformities will therefore have a purely local value. another, and less apparent physical break, which will also be locally applicable, may be due to the depression of an area to so great a depth that little or no deposit was formed upon the ocean floor there during the period of great depression; but as a break of this character is difficult to detect, the existence of unconformities has alone been practically utilised as a means of separating strata into systems owing to marked physical change, except in the cases where the lithological character of the strata completely changes, as between the triassic and jurassic rocks of england. [illustration: fig. .] palæontological breaks or breaks in the succession of organisms are in many cases, the result of physical breaks, and accordingly it is often possible to separate one set of strata from another by the existence of a combined physical and palæontological break between them. it is by no means necessary however that a physical break should be accompanied by a break in succession of the organisms, and the latter may also occur without the former. it was once maintained that a palæontological break was due to the complete and sudden extinction of a fauna and its entire replacement by a new one, but this is far from true, and accordingly the breaks differ in degree. study of the strata shows that when the succession is not to any extent interrupted, the species do not appear simultaneously, but come in at different horizons, and they disappear in the same way. in figure let _a_ represent a set of conformable strata _ab ... k_, and suppose the vertical lines represent the ranges of the various species found in these strata. it will be seen that of species whose range is shown only pass through the whole thickness, so that the fauna of _k_ is very different from the fauna of _a_, nevertheless the fauna of each stratum is closely similar to that of the underlying as well as to that of the overlying stratum, and though most of the species of _k_ are different from those of _a_, this need not be the case with the genera. the fauna of the set of strata would contain every species whose range is represented, and for convenience' sake it might be said to be composed of sub-faunas, one of which occurs in each division _ab_ ..., but the separation into sub-faunas would be artificial and merely for convenience' sake, for there is no break between any two sub-faunas. turning now to _b_ (fig. ), an attempt is made there to show what happens when there has been a physical break, resulting in the denudation of the strata _ghik_, and the deposition of another set _op_ ... unconformably upon those deposits of the earlier set which have not been denuded. as the result of this we note, first, that the relics of organisms which existed in the area during the deposition of _ghik_, and were entombed in those strata, are destroyed by the processes of denudation, and a large number of organisms which lived long after the deposition of _f_, and disappeared not simultaneously but at different times during the period when denudation was in operation, seem to become extinct simultaneously at the top of _f_, though, if we could visit an area which was receiving sediment during the period of denudation, we should find them dying out in the rocks of that region at different levels. furthermore, whilst denudation is going on, a longer or shorter period of time elapses, during which the upheaved area receives no deposit, and accordingly no organisms which lived during that period are preserved in the upheaved area. during this time a set of deposits _lmn_ may have been laid down elsewhere, and besides the gradual disappearance of some of the organisms of _ab ... k_, there will have been a gradual appearance of new species. when the upheaved area is once more submerged, a new set of deposits _op_ ... is accumulated in it, and the species which gradually appeared in adjoining regions will now migrate to it, and will seem to come in simultaneously at the bottom of _o_; accordingly we may find that there is not a single species which passes through from _f_ to _o_ and the palæontological break in this area is complete, though it is clear that it only implies local change, and that we may and indeed must find intermediate forms in other regions which fill up the gap. as an illustration of the local character of a palæontological break we may cite the case of the carboniferous and permian systems of britain. these rocks are separated from one another in our area by a physical and palæontological break, but in parts of india, and other places, we find a group of rocks now known as the permo-carboniferous rocks which contain a fauna intermediate in character between those of the permian and carboniferous systems, and a study of this fauna shows that the hiatus which exists locally is filled by the species contained in the permo-carboniferous rocks. a palæontological break may, like a physical one, result from depression of the ocean-floor to so great a depth, that no organisms are preserved there during the period of great depression, and the remarks made concerning a depression of this nature when speaking of physical breaks will apply here also. a local palæontological break may result owing to physical changes without the production of an unconformity in the area, or its submergence to a great depth, or if an unconformity is found, the break may be more marked owing to other physical changes. the difference between the upper and lower carboniferous faunas is very marked in england, where the upper carboniferous beds were deposited under physical conditions different from those of the lower carboniferous, and accordingly the corals, crinoids and other open-water animals which flourished in lower carboniferous times are rare or altogether absent in the higher rocks. where the change of conditions did not occur to a great extent as in parts of spain and north america, the similarity between the two faunas is much more pronounced. again, there is an unconformity between the cretaceous and eocene beds of england, which is accompanied by a palæontological break, but this break is more pronounced owing to difference of physical conditions, for we find abundance of gastropods in the lower tertiary beds, and a rarity of these shells at the top of the chalk of england, though where physical conditions were favourable for the growth of gastropods, their shells are found in the higher strata of chalk age, and the palæontological break is not so apparent. a palæontological break may occur also as the result of climatic change, though actual instances of this occurrence are much more difficult to detect owing to the general absence of any evidence of climatic change other than that supplied by the organisms themselves. still, when no physical break exists, and the lithological characters of a group of sediments remain constant throughout, indicating the prevalence of similar physical conditions through the period of deposition of the sediments, if the fauna suddenly changes, there must have been cause for the change, and in the absence of any other cause which is likely to produce the change, alteration of the character of the climate may be suspected. it follows from the observations which have been made, that although the rocks of the geological column may be divided into systems owing to the existence of physical and palæontological breaks, and this classification may be and has been applied generally, the line of demarcation between the rocks of two systems will be a purely conventional one, where there is no break, and, to avoid confusion, that line when once drawn should be adopted by everyone, unless good cause can be shown for its abandonment. the subdivision of systems into series has been conducted in a manner generally similar to that in which large masses of strata have been grouped into systems, with the exception that actual breaks need not occur. the subdivision was usually made on account of marked differences in the lithological characters or fossil contents of the rocks of the various series, and frequently the lithological characters as well as the fossil contents are dissimilar; taking the rocks of the silurian system of the typical silurian area as an example, we find the llandovery rocks largely arenaceous, the wenlock rocks largely calcareo-argillaceous, and the ludlow rocks argillaceo-arenaceous, whilst the fauna of the wenlock rocks differs from that of the llandovery rocks below and also from that of the ludlow rocks above. the llandovery, wenlock and ludlow therefore constitute three series of the silurian system, but the lines of demarcation between these series are nevertheless conventional, for it has been suggested that a more natural division, as far as the british rocks are concerned, could be made by drawing a line, not as at present at the base of the ludlow, but in the middle of that series as now defined, and uniting the lower ludlow beds with the wenlock strata to form a single series. the same process as that adopted in the case of series has been essentially pursued in subdividing these into stages. each stage is usually different from that above and below in its lithological characters, fossil contents, or both, though the difference is usually less in degree than that which has been utilised for the demarcation of series. a stage is often, though not always, composed of deposits of one kind of sediment, and is furthermore frequently characterised by the possession of one or, it may be, two, three or more characteristic fossils. thus the wenlock series is divided in the typical area into woolhope limestone, wenlock shale, and wenlock limestone, and the very names given to these stages indicate that each is largely composed of one kind of material. their fossils are also to some extent different, though the difference between them is not likely to be of so marked a nature as that which exists between the faunas of separate series. it will be seen that the system differs from the series and the series from the stage in degree rather than in kind, and no hard line can be drawn between divisions of different degrees of magnitude. it follows therefore that frequently a mass of sediment which one author will consider sufficiently important to constitute a system will be defined by another as a series, and similarly a series of one writer may become a stage of another. the student of stratigraphical geology will find the expression 'fossil zone' occurring over and over again in geological literature, and as the term has been used somewhat vaguely by many writers and is apt to be misunderstood, it will be useful to notice the expression at some length. strictly speaking the term zone (a belt or girdle), when applied to distribution of fossils, should refer to the belt of strata through which a fossil or group of fossils ranges. generally speaking, the expression is used in connexion with one fossil; thus we speak of the zone of _coenograptus gracilis_, the zone of _cidaris florigemma_ and the zone of _belemnites jaculum_, though sometimes it is used with reference to more than one species, as the zone of micrasters and the _olenellus_ zone. the term has been used not of a belt of strata but of a group of organisms[ ], and zones defined as "assemblages of organic remains of which one abundant and characteristic form is chosen as an index," but if it be agreed that the term should be applied to strata and not to organisms this might be modified and the definition run:--'zones are belts of strata, each of which is characterised by an assemblage of organic remains of which one abundant and characteristic form is chosen as an index.' [footnote : see h. b. woodward, "on geological zones," _proc. geol. assoc._, vol. xii. part , p. , and vol. xii. part , p. .] it has been objected that the subdivision of strata into zones has been pushed too far, but this is merely because in the establishment of zones, workers find it easier to work out the successive zones where the strata are thin and presumably deposited with extreme slowness, than where they are much thicker and have been rapidly accumulated, and accordingly, as the subdivision of strata into zones is a recent event, geological literature contains many more references to thin zones than to those of great thickness. where an abundant and characteristic form (which is chosen as an index) of an assemblage of organic remains ranges through a great thickness of deposit, there is no objection to speaking of the whole as a zone, and it cannot be divided. to give some idea of the variations in the thickness of strata through which these abundant and characteristic forms will range, i append a list of the zones of graptolites which have been established amongst the silurian rocks of english lakeland and the thickness of each (which in the case of the thicker deposits is naturally only approximate):-- thickness. zone of feet. inches. _monograptus leintwardinensis_ _monograptus bohemicus_ _monograptus nilssoni_ _cyrtograptus murchisoni_ _monograptus crispus_ _monograptus turriculatus_ _rastutes maximus_ _monograptus spinigerus_ _monograptus clingani_ _monograptus convolutus_ _monograptus argenteus_ _monograptus fimbriatus_ _dimorphograptus confertus_ _diplograptus acuminatus_ it must not be supposed that each of the subdivisions in the above list is of equal importance, and has occupied approximately the same length of time for its formation, but a study of the strata proves by various kinds of evidence that the deposits in which the characteristic forms range through a small thickness of rock were on the whole deposited much more slowly than where the range is continuous through a great thickness of deposit. the geological systems, as originally founded, were not very accurately separated from one another except locally. a comprehensive view of the characters of a system was taken, and accordingly the lines of demarcation between the same systems adopted by workers in different countries were by no means necessarily at or near the same geological horizon. as the result of more recent work, the establishment of fossil zones has been growing apace, and though many of these are seen to have only local significance, it is found as the result of experience that many of them are widely spread and occur in the same order in different localities; accordingly the remarks that have been made concerning the contemporaneity of strata apply to these zones also. after a study of this kind, a much more accurate comparison of strata is possible, and correlation of strata can be carried on to a much greater extent than when the systems were only roughly subdivided by reference to breaks, differences of lithological character, and general comparison of the faunas; accordingly whilst largely retaining the old names, the old method of classification is being partly superseded, and the included faunas alone are utilised to establish accurate correlations of the strata in various parts of the world. how far this correlation can be carried on remains to be seen, for the work though well advanced has by no means reached completion, and predictions as to the ultimate issue are useless without the experience by means of which only the work can be done. the difference between the methods of classification is well shown by an examination of the old and new divisions of the chalk. it was formerly roughly divided mainly by lithological characters into chalk marl, lower chalk without flints, middle chalk with few flints and upper chalk with many flints, but no two observers would probably agree as to where the deposit with few flints ceased and that with many commenced. the chalk is now separated on palæontological grounds into cenomanian, turonian, senonian and danian, and the superiority of the new method to the old is practically shown by the abandonment of the old classification except for very rough purposes, and the general acceptance of the new one. many other examples might be given, but this one will suffice. in the case of some of the systems, the carboniferous for example, the old classification founded upon lithological characters is largely extant, and it has been inferred therefore that no accurate subdivisions of the carboniferous rocks can be made by reference to the faunas, owing to the rapidity with which the deposits were accumulated. it is by no means certain because the work has not been done that it cannot be done, and the experience obtained from a study of other strata in which subdivisions have been established by reference to the fauna would lead one to suppose that the non-establishment of subdivisions of the carboniferous strata is due to our want of knowledge rather than to their non-existence. the establishment of a classification on palæontological lines by no means does away with the necessity for local classifications on a lithological basis, and it has already been remarked that important results will follow from a comparison of the classifications of sediments founded on the two lines, results which have hitherto largely escaped our attention owing to the existence of a cumbrous classification attained by the application sometimes of one method, at other times of the alternative one. chapter vii. simulation of structures. although it is easy to give an account of the structures which are of importance to the student of the stratified rocks, actual observation of these structures is frequently attended with difficulties owing to the close imitation of one structure by another, and the past history of the science shows that erroneous conclusions have been reached again and again on account of the incorrect interpretation of structures. simulation of organisms has frequently been the cause of error. inorganic substances take on the form of organisms with various degrees of closeness. the dendritic markings produced by efflorescences of oxide of manganese are familiar to all, and as the name implies, they simulate, to some extent, plant remains. more complex chemical changes have resulted in the production of rock-masses in which, not the outward form alone but, the internal structure of organisms is reproduced with more or less approach to fidelity, as the rocks which contain the supposed organisms described as _eozoon bohemicum_, _e. bavaricum_, and, we may add, _e. canadense_. mechanical changes in rocks subsequent to their formation may also cause the simulation of organisms by inorganic substances. prof. sollas has given reasons for considering the structure described as _oldhamia_ to be inorganic, and in the carboniferous sandstones of little haven, pembrokeshire, every stage in the formation of tubular bodies resembling worm-tubes, as the result of complex folding of the strata, may be observed, whilst in other cases we find imitation of worm-tracks, as has been observed before. it is when one inorganic structure is simulated by another that the stratigraphical geologist is most likely to be led astray, and accordingly it is worth noting some cases where this has occurred, as a warning, for it must not be supposed that the cases here noted are the only ones which are likely to occur. it has been seen that the existence of bedding-planes is of prime importance to the geologist, and their detection is a matter of supreme moment. under ordinary circumstances there is no great difficulty in distinguishing bedding-planes from other planes, but the importance of discovering them is often greatest when the difficulty is most pronounced. in rocks which have undergone no great amount of disturbance the planes of stratification are often marked by their regular parallelism, the separation of layers having different lithological characters by these planes, the arrangement of the longer axes of pebbles parallel to them, and the occurrence of fossils and also of rain-prints, ripple-marks and other structures produced during deposition, upon the surfaces of the strata, but none of these appearances is necessarily conclusive, especially in areas where the rocks have been subjected to orogenic movements. in regularly-jointed rocks, jointing may well be mistaken for bedding, and there is often great difficulty in discriminating between bedding and cleavage, especially when the exposures of rock are of small extent. fossils may be dragged out along planes at an angle to the true bedding, pebbles will be compressed by cleavage so that their longer axes do not remain parallel to the bedding-planes but now lie parallel to the superinduced planes of cleavage, and a structure closely resembling 'ripple-mark' may be produced on planes other than those of original bedding, as the result of puckering. the alternation of rocks having different lithological characters may also be misleading. intrusion of dykes along cleavage-planes, followed by decomposition of the dyke-rock causing it to resemble a sediment, and formation of mineral veins along the same planes, may give rise to an apparent succession of rocks of different lithological characters which could easily mislead an observer and cause him to mistake the cleavage-planes for planes of stratification. in rocks which have undergone great lateral pressure, the beds of different lithological character may be folded in such a way as to give very erroneous ideas of the true dip of the rock on a large scale. in fig. the dip of the rocks in a small exposure might appear to be in the direction indicated by the unfeathered arrow, whilst the true dip of the strata as a whole, leaving the minor foldings out of account, is in the direction of the feathered arrow, at the inclination represented by the dotted line. the minor folds in a case like that represented may extend upwards for scores or even hundreds of feet, so that an error as to the direction and amount of dip may be made, even if the observer faces a cliff of considerable height. [illustration: fig. .] false-bedding on a large scale may be a cause of error. in the penrith sandstone of cumberland, the planes of deposition are often found dipping in one direction in a large quarry, but inspection of a wider area shows that this is not the true dip of the beds as a whole, but merely a local dip due to deposition on a slope, and any one attempting to calculate the total thickness of the beds by reference to these divisional planes might be seriously led astray. a reference to fig. will explain this. the lines _aa´_, _bb´_ are the true bedding-planes cut across in the section, whilst the lines sloping to the right from _xx_ are only lines of false-bedding on a large scale. an exaggerated estimate of the thickness of the deposit would be made by measuring the thickness of each of these stratula from _a_ to _a´_ and adding these thicknesses together, whereas the actual thickness of the middle bed is the distance between _a_ and _b_ or _a´_ and _b´_. [illustration: fig. .] when rocks have been affected by thrust-planes, the simulation of bedding may be carried out to a very full extent. not only do the major thrust-planes resemble bedding-planes but the minor thrusts produce an appearance of divisional planes separating stratula or laminæ, and a close approximation to false-bedding is the result. to this structure prof. bonney has given the name 'pseudo-stromatism[ ].' it may be developed in rocks of all kinds, whether possessing original planes of stratification or not, and as a result of its existence the geologist may be seriously misled, not merely by mistaking the direction of the strata, but also the nature of the rock, for we may find it produced in an unstratified glacial till, and in a massive igneous rock, and in each case the resulting rock will resemble a sedimentary deposit, and of course the observer may be confirmed in his erroneous opinion by the formation of apparent fossils, ripple-marks or other objects which he might expect to discover in sediments. as illustrative examples, reference may be made to a number of schistose rocks, in which the planes of discontinuity (which are in truth planes of foliation) have been taken for bedding-planes and the rocks claimed as sedimentary though they are in reality igneous; for instance many of the rocks of the laurentian of canada, of the hebridean of the north west highlands, and some of the ancient rocks of anglesey. [footnote : bonney, t. g., _quart. journ. geol. soc._, vol. xlii. _proc._ p. .] a foliated structure may, as is now well known, be simulated by a structure developed in a rock prior to its consolidation. the similarity of flow structure of some lavas to the foliated structure of a schist was long ago pointed out by darwin and scrope, and recent work has proved that parallel structure due to differential movement prior to consolidation may be developed in plutonic rocks, as shown by lieut.-general mcmahon in the himalayan granites, and by lawson amongst the plutonic rocks of the rainy lake region; and as the foliated structure may be mistaken for original stratification the same may occur, and has occurred, when dealing with this flow-structure. this is not the place to discuss the truth of the old theory of progressive metamorphism, in which it was maintained that a gradual passage could be traced between ordinary sediments and plutonic rocks, but it may be pointed out that much of the evidence which was relied upon to prove the theory was fallacious and due to the confusion of the parallel structure set up in plutonic rocks prior to, or subsequent to, consolidation, with original stratification. recent study of metamorphic rocks has proved that the parallel structures developed in the rocks of an area which has undergone metamorphism may be produced by three distinct processes; they may be original planes of deposition, or formed in a solid rock subsequently to its formation, or in an igneous rock before its consolidation, and although it is sometimes possible to separate the structures produced by these processes, this is not always the case[ ]. when a plutonic rock contains large phenocrysts and an eye-structure is developed in it, it may simulate a conglomerate, the rounded phenocrysts being taken for pebbles[ ]. still closer simulation of an epiclastic conglomerate may be produced in other ways and will be referred to immediately. [footnote : it must be noticed that the rock in which parallel structure is produced before consolidation, if it undergoes no further change, though often associated with metamorphic rocks, is not itself metamorphic. the term _gneiss_ applied to these rocks is a misnomer, unless the term be used even more vaguely than it is at present.] [footnote : see lehmann, _untersuchungen über die entstehung der altkrystallinischen schiefergesteine mit besonderer bezugnahme auf das sächsische granulitgebirge_, plate xi. fig. .] we have already seen that the existence of unconformities has been utilised in the demarcation of large divisions of strata in various regions, and whether they be utilised in this manner or not, their detection is a matter of importance to the stratigraphical geologist, as they afford information concerning the occurrence of great physical changes during their production. these unconformities may also be closely simulated by structures produced in very different manner. the occurrence of an unconformity implies the denudation of one set of beds before the deposition of another set upon them, and accordingly the denuded edges of the lower set will somewhere abut against the lower surface of the lowest deposit or deposits of the overlying set[ ]. the existence of an unconformity may often be detected in section, but when the unconformity is upon a large scale this may not be possible, but it will be discovered by mapping the strata and will be apparent on a map owing to the deposits of the lower set of beds abutting against the others. this is well seen where the permian rocks of durham, yorkshire, and nottinghamshire rest upon different members of the underlying carboniferous series, and will be noticed on any good geological map of england. but a similar effect may be caused by a fault, so that mere inspection of a map or even of the strata in the field and discovery of one set of beds ending off against another does not prove unconformity. when the fault is a normal one, with low hade (that is, having a fissure approaching the vertical position), the outcrop of the fault-fissure will approximate to a straight line if the fault has a straight course, even if the ground be very uneven, whereas, if the plane of unconformity has not been tilted to a high angle from its original horizontal position, it will crop out in a sinuous manner across uneven ground, in a way similar to that of beds which are nearly horizontal, so that though the general trend of the outcrop of the plane of unconformity may be fairly straight, its deviation from a straight line will be frequent and marked, as seen in the case of the permian unconformity above referred to. but if the unconformable junction has been highly inclined its outcrop will resemble that of a normal fault, or if the fault be a thrust-plane with high hade, the outcrop of this will resemble that of an unconformable junction which has not been greatly tilted from its original horizontal position. in these cases we require more evidence before we can decide whether we are dealing with an unconformable junction or a faulted one. [footnote : an unconformity may be simulated or an actual unconformity rendered apparently more important, as the result of underground solution of the underlying strata subsequently to the deposition of the upper set upon them, and any insoluble materials in the underlying strata may be left as an apparent pebble-bed at the base of the upper beds. this is seen at the junction of the tertiary beds with the chalk near london. subterranean water has dissolved the upper part of the chalk, increasing the unconformity which naturally exists between chalk and tertiary beds, and the insoluble flint of the dissolved chalk is left as a layer of 'green-coated flint' at the base of the tertiary deposits.] the lowest deposits of the newer set of strata lying above an unconformity have probably been laid down in water near the shore-line. as the unconformity, if large, implies elevation above the sea-level, the deposits first formed after this elevation has ceased, and depression commenced, will necessarily be littoral in character and possibly of beach-formation, and accordingly we often find that an unconformity is marked by the existence of an epiclastic conglomerate immediately above the plane of unconformity and, although this need not be continuous, it is usually found somewhere along the line of junction. the conglomeratic base of the lowest carboniferous strata when they repose upon the upturned edges of the lower palæozoic rocks of the dales of west yorkshire is well known, and may be cited as an example. the association of conglomerates with unconformities is indeed so frequent that its possible occurrence will always be suspected and sought by the geologist. unfortunately the result of recent observation is to show that along thrust-planes of which the outcrop simulates those of unconformable junctions, the difficulty of discrimination may be increased by the existence of cataclastic rocks which bear a close resemblance to epiclastic conglomerates, and which may be and have been styled conglomerates. it is well known that fragments of the adjoining rocks are knocked into a fault-fissure during the occurrence of the movements which cause the fault, to constitute a _fault-breccia_, and as the result of the abrasion of these fragments by chemical or mechanical agency, the angular fragments may become rounded and converted into rounded pebble-like bodies, when the rock is changed into a _fault-conglomerate_. fig. , from a photograph kindly supplied by prof. w. w. watts, shows a stage in the formation of a conglomerate of this nature from a fault-breccia; the fragment on the right remains angular, whilst those on the left have become much more rounded. the illustration is from a case described by mr lamplugh occurring in the slaty rocks of the isle of man, and mr lamplugh's paper[ ] furnishes the reader with references to other examples of the production of similar rocks. no general rule can be laid down for distinguishing the true from the apparent unconformity, for the attendant phenomena will differ in each case; but if a fault-conglomerate should be suspected, the observer should try to ascertain whether fragments of a newer rock are imbedded in an older one, which sometimes occurs; he should note the existence of extensive slickensiding along the plane of junction and along planes of faulting, though the existence of these, implying as it does the occurrence of differential movement along the plane, does not prove that the movement was necessarily great, or that it did not take place along a plane of original unconformity; above all, he should look for structures such as mylonitic structure, pseudo-stromatism, development of new minerals, crushing out and stretching of fossils and fragments and, in short, for any structure which is familiar to him as a result of orogenic movements. [footnote : lamplugh, g. w., "on the crush-conglomerates of the isle of man," _quart. journ. geol. soc._, vol. li. p. .] [illustration: fig. .] the effects of thrusting not only give rise to appearances suggestive of unconformity, but naturally also to a simulation of overlap. the thrust-planes are often parallel to original bedding-planes for some distance, but must cut across them sooner or later, producing lenticular masses which might be supposed to be due to the thinning out of beds as the result of cessation of deposition in a lateral direction. attention has already been directed to the deceptive appearance of great thickness of strata which is due to repetition of one stratum or set of strata by a series of thrust-planes, so that there is no actual inversion of any part of a bed. when masses of limestone are affected in this way, the thrust-planes may become sealed up, as the result of chemical change, and a compact irregular mass of limestone devoid of any definite divisional planes may be the consequence, and beds of grit sometimes exhibit the same feature to some extent. enough has been said to show that simulation of one structure by another has frequently occurred in rocks in so marked a degree as to render mistakes easy; and that these examples of 'mimicry' in the inorganic world are particularly frequent in rocks which have been subjected to great orogenic movements. the student will do well to acquaint himself with the macroscopic and microscopic structures which may be taken as characteristic of the rocks which have been thus affected, some of which can usually be detected with ease, and when he discovers them he may suspect that many phenomena which appear explicable in one way were in reality produced in a different one, for it is frequently very true of a region in which the rocks have been violently squeezed, stretched and broken that 'things are not what they seem.' chapter viii. geological maps and sections. the writer does not propose to give an account of the intricacies of geological mapping, for their right consideration requires a separate treatise[ ]; all he desires is to call attention to some of the uses of geological maps as a means of conveying information. a geological map may be looked upon as an attempt to express as far as possible in two dimensions phenomena which possess three dimensions; this can be done to some extent on the actual surface of the map, by conventional signs, still more fully, by supplementing the map with sections; but best of all by a geological model, which is cut across in various directions in order to show the underground structure as well as that of the surface. [footnote : the student is recommended to consult in particular, appendix i. "on geological surveying" in _the student's manual of geology_, by j. b. jukes (third edition, edited by a. geikie), p. , and _outlines of field geology_, by sir a. geikie (macmillan and co.).] the ordinary geological map is one which shows the outcrop of the strata, subdivided according to age, as they would be seen upon the surface of the earth after stripping off the superficial accumulations, and it is to be feared that the term 'geological map' is associated in the minds of most students with a map of this character and of no other. nevertheless, a great many most important observations other than those connected with the order of succession of the strata are capable of representation upon a geological map, and the possession of a large number of maps of any area upon the geology of which a person is engaged--each map to be used for recording observations of a particular kind--will save much writing in note-books and, what is of more importance, will allow him to compare observations which have been made at different times at a glance, instead of causing him to search through a series of note-books. still, however well furnished with maps, the geologist will find a note-book essential[ ]. [footnote : as a result of some experience, the writer recommends every student to acquire some skill in the use of the pencil, and if to such a degree that he can combine artistic effect with accuracy, so much the better. an acquaintance with photography is invaluable: often the possession of a camera would enable a section to be recorded, which is otherwise lost to science.] the earliest geological maps represented the variations in the surface soils, or at most the general lithological characters of the rocks which by their decay furnished the materials for the soils. we have seen that the first chronological map was due to william smith, and most subsequent english geological maps have been based upon his map of the strata of england and wales. the order of succession of the strata is represented in these maps to some extent by the use of arrows to indicate the direction of dip of the strata, though this is not an unerring guide where strata are reversed, and accordingly the addition of a legend at the side of the map may be looked upon as essential to the correct understanding of the map itself. the legend is usually in the form of a section of a column, the strata being arranged in right order, the oldest at the base and the newest at the summit, the colours by which the strata are indicated being similar to those placed upon the map. other information besides the mere order of succession of the strata may appear in the legend; thus their relative and actual thicknesses can be indicated if the column is drawn to some definite scale, and a brief description of the lithological characters of the rocks may well be appended to the side of the column. on the actual maps it is customary to exhibit the outcrop of the junctions of all igneous rocks as well as of the sedimentary ones: the nature of the metamorphism which sedimentary rocks have undergone at the contact with igneous ones may be and often is indicated by suitable signs; the position of faults is shown, and often also that of metalliferous veins, the nature of the ore in the latter being further indicated in some suitable manner, as by giving the recognised symbol for the metal; and in many maps an attempt is made to show the variations in dip and strike of the cleavage-planes. the geological survey of the united kingdom publishes two sets of maps, one showing the 'solid geology' and the other the 'superficial geology.' it is easier to understand these terms than to define them, for in britain there is a sharp line between the two everywhere except near cromer. the maps showing the superficial geology represent gravels, glacial drifts and other incoherent accumulations of geologically recent origin, which to a greater or less extent mask the strata below which are usually composed of more or less solidified material. the maps showing the solid geology display the outcrops of these strata, though it is usual to insert alluvium upon these maps, as it is often impossible to trace the junction-lines of the strata below it. attention has already been directed to the fact that these maps of solid geology, though chronological, that is, having the strata represented according to age, are founded largely upon lithological differences, rather than upon included organisms; and it has been stated that for theoretical purposes two sets of chronological maps, one founded upon lithological differences, the other upon difference of fossil organisms, would be extremely valuable. other phenomena are often best represented upon separate maps, for if all observations are crowded upon one map the result will be very confusing. special glacial maps showing the contour of the country, with the portions between the contour lines coloured differently according to altitude, say the country between sea-level and feet light green, that between and dark green, that between and light brown and so on, exhibiting the direction of all observed glacial striae, the distribution of boulders so far as it is possible, and any other glacial phenomena which can be noted upon the map, will be valuable to the student of glaciation[ ]. [footnote : for examples see tiddeman, r. h., "evidence for the ice-sheet in north lancashire and the adjacent parts of yorkshire and westmorland," _quart. journ. geol. soc._, vol. xxviii. pl. xxx., and goodchild, j. g., "glacial phenomena of the eden valley" &c., _quart. journ. geol. soc._, vol. xxxi. pl. ii.; and for a map of distribution of boulders, ward, j. c., "geology of the northern part of the english lake district" (_mem. geol. survey_), pl. iv.] various structural features may be well displayed on separate maps. the trend of the axes of folds will be useful, and may be accompanied by other information of cognate character[ ]; maps of the distribution of joint planes may be given in combination with those showing the folding of the strata if it be desired to exhibit the relationship between these; or with the physical features of the country, if the dependence of physical features upon joint structure be under consideration[ ]. much information concerning cleavage may be acquired from a map showing anticlinal and synclinal axes of cleavage[ ], or the actual strike of the cleavage over different parts of a map may be represented, and its relationship to the geological structure of the district exhibited[ ]. [footnote : see bertrand, m., "sur le raccordement des bassins houillers du nord de la france et du sud de l'angleterre," _annales des mines_, jan. , plate .] [footnote : see daubrée, a., _Études synthétiques de géologie expérimentale_, ^{ère} partie, plates iii.-vi., for an example of the latter, which is also interesting as showing the utility of a map on transparent paper super-posed on another, when illustrating the connexion between two sets of structures.] [footnote : ward, j. c., _geology of the northern part of the english lake district_, plate ix.] [footnote : harker, alfred, "the bala volcanic series of caernarvonshire" (_sedgwick essay_ for ), fig. .] maps exhibiting changes in physical geography appertain to the geologist as well as to the geographer. the position of ancient beaches, former lakes, representation of the changes in the courses of rivers and kindred phenomena may be shown upon maps, and will prove useful[ ]. [footnote : for examples of maps of this kind, see kjerulf, th., _die geologie des südlichen und mittleren norwegen_.] a perusal of the maps to which reference has been made above will give the student some notion of the extent to which maps may be utilised to represent geological structures, and may suggest other methods by which they may be utilised. a geological section is usually drawn in order to exhibit the lie of the rocks, as it would be seen if a vertical cutting were made in that part of the earth's crust which is under consideration. the character of the section will depend upon circumstances. the geological survey of great britain issues two kinds of sections which are usually spoken of as vertical sections and horizontal sections, though each is in truth a vertical section; but whereas in the former the horizontal distance represented is small as compared with the thickness of the strata, in the latter the rocks of a considerable horizontal extent of country are exhibited in the section, and the section is not carried down to a great depth below the earth's surface. there is no essential difference between the two kinds of section, and often sections are drawn which cannot be definitely classed as belonging to either kind, but in extreme cases the vertical section is a representation of the order of succession as it would appear if the rocks were horizontal, no matter how disturbed they may be in reality; whereas the horizontal section represents the strata as they actually occur, with all the folds and faults by which they are affected. the accompanying figure (fig. ) represents a horizontal section on the left side of the figure with a vertical section of the same rocks on the right side. [illustration: fig. .] vertical sections are extremely useful when it is desirable to compare variations in the strata over wide extents of country: this can be done by drawing a series of columns of the strata, each showing in vertical section the lithological characters and thicknesses of the strata in one place, whilst the relationship between the strata of two different places may be indicated by joining the beds of the same age by dotted lines as shown in fig. [ ]. [illustration: fig. .] [footnote : it is useful to adopt conventional symbols for the representation of strata of different lithological characters, and so far as possible to adhere to the same kind of symbol for any one kind of deposit. those which are generally in use, are rough pictorial representations of the characters of the deposits, as shown in fig. . the conglomerate is indicated by circular marks representing cross-sections of the pebbles, a breccia by triangular marks signifying that the fragments are angular and not rounded; a sandstone is indicated by dots to represent the grains of sand; a mud, clay or shale by continuous or broken horizontal lines, which reproduce the appearance of the planes of lamination so frequent in beds of this composition; a limestone is usually marked by the use of regular horizontal lines illustrating the pronounced bedding, with vertical lines at intervals to represent the regular jointing which occurs in so many limestones: the nature of the bedding may be further shown by drawing the lines comparatively far apart when the limestone is a thick-bedded one, nearer together when it is thin-bedded. igneous rocks are represented by crosses or irregular v-shaped marks, illustrating the absence of stratification and presence of joints. volcanic ashes are sometimes represented by dots, at other times by signs somewhat similar to those which are used for true igneous rocks. sedimentary rocks which are composed of more than one kind of material may be further shown by a combination of two symbols, thus the existence of a sandy clay may be shown by means of a combination of horizontal lines and dots, and so with other combinations. the practical geologist should become accustomed to the use of these symbols in his note-book; if used, they will save much writing. these symbols are used in some of the later illustrations to this book.] the horizontal section is one which is in constant use by the practical geologist: the results of the first traverse of a district may be jotted down in his note-book in the form of a horizontal section (with accompanying notes), and the written memoir on the geology of any district composed largely of stratified rocks will almost certainly require illustration by means of these sections. perhaps nothing more clearly marks the careful observer than the nature of the sections which he makes, and geological literature is too frequently marred by the publication of slovenly sections. a badly drawn section not only offends the eye, it may and frequently does convey inaccurate information. [illustration: fig. .] in the above figure (fig. ) taken from sir henry de la beche's "sections and views illustrative of geological phænomena," plate ii., the lower drawing represents a section drawn to true scale, while that above shows one which is exaggerated. the student who saw this would infer that the uppermost beds on the left side of the upper section rested unconformably upon the dotted beds beneath, and once abutted against them in that portion of the figure where the beds have been removed by denudation in the deep valley, whereas an examination of the section drawn to true scale shows that the unconformity does not exist (although there is one at the base of the deposits marked by dots), and that there is room for the higher deposits to pass above those marked by dots at the place where the former have been removed by denudation. whenever possible, horizontal sections should be drawn to true scale, the vertical heights being on the same scale as the horizontal distances. sections which are so drawn represent the nature of the surface of the country as well as the relationship of the strata, and often illustrate in a marked degree the influence which the character of the strata has exerted upon the nature of the superficial features of a country. if it be impossible to draw a section in which the elevations and horizontal distances are represented upon a true scale, the former ought to be drawn on a scale which is a multiple of the latter; thus the vertical heights may be shown on , , or or more times the scale chosen for the horizontal distances; when this is done, it will often be necessary to show the strata with an exaggerated dip, and accordingly the exaggerated section loses some of its value, though if vertical and horizontal scales bear some definite proportion it will still be more valuable than a rough diagram which is not drawn to any scale. section-drawing cannot be satisfactorily accomplished without some practice, and the student is strongly advised to acquire the art of drawing good sections; the writer can assert as the result of considerable experience in the conduct of examinations of all kinds, that slovenly sections are the rule in candidates' papers, and good sections very rarely appear. study of the six-inch maps and horizontal sections (drawn on the same scale) of the geological survey of the united kingdom will enable the student to familiarise himself with admirable sections, and it should be his aim to produce sections like these. he is recommended to take some of these six-inch maps which show contour-lines as well as the disposition of the strata, and to draw sections on the scale of six inches to the mile, vertical and horizontal, exhibiting the proper outline of the ground and the arrangement of the strata, and afterwards to compare them with the published sections. the sections should be drawn as far as possible at right angles to the general strike of the strata. some datum-line is taken for the base of the section (say sea-level) and offsets drawn vertically from this where the section crosses a contour-line or recorded height. the height is marked on these offsets; thus if a recorded height of feet (just over half a mile) occurred on the line of section a height of somewhat over three inches is marked on the offset, and so with the other points where the section crosses contours or recorded heights. by joining these points on the offsets, giving the connecting lines curves similar to those which are likely to occur in nature, the general character of the surface of the ground is represented. the geology of the district is next shown. wherever a dip is marked on the map, the direction and amount of dip is shown by a short line on the section, and where dips are not actually seen along the line of section, the dips which are nearest to that line on the map must be considered, and marked on the section. the lines of junction between the various deposits shown by different colours upon the map are inserted on the section as short lines, the inclination being judged by study of the nearest dips; faults and igneous rocks must be marked off, and any indication of the hade of the fault or the slope of the edges of the igneous rock which the map affords will be taken into account. the section will then appear somewhat as shown in the following figure: [illustration: fig. .] and sufficient indication of the trend of the rocks will be obtained to shew that they form portions of curves which may then be filled in as shown in fig. and the section will be complete. [illustration: fig. .] it will be noticed that the small dyke of igneous rock on the right of the main dyke is joined to it lower down, though no indication of this is given along the line of section; but the requisite information for this and evidence of the existence of the small dyke proceeding from the left-hand side of the main one may be obtained by the study of the rocks in a valley on one side or other of the line of section. after the student has become conversant with the nature of geological maps and sections, and has read sir a. geikie's _outlines of field geology_, he should on no account omit to learn something of the art of making geological maps, by going into the field and attempting to produce a map, for the art of geological surveying does not come naturally to any one, and some acquaintance with the methods of surveying is a necessity to everyone who wishes to make original geological observations, though all cannot expect to afford the time and acquire the skill necessary for the production of maps vying with the detailed maps of the government survey. before actually attempting to draw lines on a map on his own account, he will do well to tramp over a portion of a district with the published geological map in his hands, selecting a country which is not characterised by great intricacy of geological structure, and he can then attempt to represent the geology of another portion of the same district without consulting the published map. of all the districts of britain with which he is acquainted the writer believes that the basin of the river ribble, in the neighbourhood of the town of settle in the west riding of yorkshire, is best adapted for studying field geology in the way suggested above, for the main geological features are marked by extreme simplicity, and the exposures are good, whilst the presence of an important fault-system and of a great unconformity relieve the area from monotony. anyone who stands on the summit of ingleborough or penyghent will grasp the main features of a portion of the district without any difficulty, for it lies beneath his feet like a geological model, and when the student has mastered and mapped in the leading features, he can find bits of country with geology of varying degrees of complexity amongst the lower palæozoic rocks of the valleys which run down to ingleton, clapham, austwick and settle. the biologist is supplied with laboratories at home and abroad, where he may study his science under the best conditions. would that some munificent person would found, in a district like that referred to above, a geological station where cambridge students would have the means of acquiring a knowledge of field-geology under conditions more favourable than those presented by the flats around the sluggish cam! chapter ix. evidences of conditions under which strata were formed. the establishment of the order of succession of the strata, and the correlation of strata of different areas merely pave the way for the geologist. to write the history of the earth during various geological ages, he has to ascertain the physical and climatic conditions which prevailed during the successive geological periods, and to study the various problems connected with the life of each period. in the present chapter an attempt will be made to illustrate the methods which have been pursued in order to write to the fullest degree which is compatible with our present knowledge, the earth-history of various ages of the past. in making this attempt, the physical and climatic conditions may be first considered, and their consideration followed by that of the changes in the faunas, though it will frequently be necessary to refer to one set of conditions as illustrative of the other. it will be assumed here that the great principle of geology, that the modern changes of the earth and its inhabitants are illustrative of past changes, is rigidly true. reference will be made to this principle in a later chapter, but it is sufficient to state here that the study of the sediments which have been deposited from the commencement of lower palæozoic times to the times in which we now live bear the marks of having been formed under physical conditions, which, in the main, are similar in kind to those which prevail upon some part of the surface of the lithosphere at the present day. one of the most important inferences of the stratigrapher relates to the existence of marine or terrestrial conditions over an area at any particular time, and we may, in the first place, consider the evidence which supplies us with a clue to this subject. it has been previously stated that the ocean is essentially the theatre of deposition, the land that of destruction, and accordingly, the presence of deposit as a general rule indicates the evidence of marine conditions during the formation of those deposits, though this is not universally the case. again, as denudation is practically confined to the land areas, and the shallow-waters at their margins, unconformity on a large scale gives evidence of the existence of terrestrial conditions in the area in which it is developed, during its production. accordingly a mass of deposit separated from deposits above and below by marked unconformities shows the alternation of terrestrial conditions (during which the unconformity was produced) and marine conditions (during which the deposits were laid down). the deposits formed after an unconformity has been developed will naturally be of shallow-water character, as will also be those of the period immediately preceding the incoming of conditions which will cause the occurrence of another unconformity, and between these two shallow-water periods will occur a period when deeper-water conditions probably prevailed. we can therefore not only divide the history of any particular area into a series of chapters, of which every two successive ones will describe a continental period and a marine one, but each marine period may be divided into three phases--a shallow-water phase at the commencement, an intermediate deeper-water phase, and a shallow-water phase at the end. these phases are frequently complicated by the occurrence of a host of minor changes, but on eliminating these, the effects of the three great phases are shown by study of the nature of the strata, and their recognition does much to simplify the detailed study of the stratigraphical geology of various parts of the earth's surface. in discriminating between terrestrial conditions and marine ones, the existence of unconformities is of great importance in marking terrestrial conditions and is often the only available evidence, for no accumulations or deposits formed on the land may be preserved to testify to the terrestrial conditions[ ]. when terrestrial deposits and accumulations do occur, they are extremely important, and it is necessary to allude to the points wherein they differ from marine deposits. [footnote : the term terrestrial is used above in opposition to marine, to include the conditions prevalent above sea-level. the term continental would be better if it did not exclude insular conditions. accordingly deposits formed in rivers, and fresh-water and salt-water lakes are spoken of as terrestrial.] apart from organic contents, the mechanically formed deposits of rivers and lakes resemble in general characters the shallow-water deposits of the ocean, though they are usually less widely distributed. it is the accumulations which have actually been formed as æolian rocks, or those which have been laid down as chemical precipitates in salt-lakes which, by study of lithological characters, furnish the most convincing evidence of their terrestrial origin. many æolian accumulations may be looked upon as soils, if the term soil be used in a special sense to refer to the accumulations which are produced as the result of the excess of disintegration over transportation in an area, whilst others are due to transport which has not been sufficiently effective to carry the material to the sea. when the weathered material accumulates above the weathered rock, it depends chiefly upon climate whether the disintegrated rock becomes mingled with much decayed organic matter forming humus. if this organic matter exists in quantity, the probability is that the accumulation is a terrestrial one, though this is by no means necessarily the case, for under exceptional circumstances a good deal of humus may be deposited in the sea, as beneath the mangrove-swamps which line the coasts of some regions, and to go further back, in the case of the cromer forest series of pliocene times, or some coals, such as the wigan cannel coal of the carboniferous strata. in addition to the work of water, which affects both land and sea-deposits, the land is especially characterised by the operations of wind and frost upon it, for these produce results which may frequently serve to differentiate a land-accumulation from a deposit laid down beneath sea-level. the effect of wind in rounding the grains of sand which are blown by it is well-known, and samples of the 'millet-seed' sands of desert regions are preserved in most museums. the greater rounding which characterises wind-borne as compared with water-borne sand grains is due, in great measure, to the greater friction between the grains when carried by the air than when swept along by the water. under favourable circumstances water-worn grains may become rounded, especially when agitated by gentle currents sweeping over a shoal[ ]; but a large mass of sand, in which most of the grains have undergone much rounding so as to give rise to 'millet-seed' sand, will nevertheless be probably formed by wind-action except where a marine deposit is formed of material largely derived from an earlier æolian one. the effect of frost is to split rocks into fragments which are more or less angular before they are subjected to water-action. the broken fragments are prone to collect on slopes as screes, and as any scree-material falling into the sea is likely to become rounded except under conditions which rarely prevail, the existence of much scree-material in a rock suggests its terrestrial origin. glaciers gave rise to terrestrial moraines, which may occasionally be identified as land-accumulations by mere inspection of their physical characters, but all geologists are aware of the difficulties with which they are confronted when they attempt to discriminate between terrestrial and marine glacial deposits. [footnote : cf. hunt, a. r., "the evidence of the skerries shoal on the wearing of fine sands by waves," _trans. devon. assoc._, , vol. xix. p. .] the existence of much material amongst the stratified rocks which has been precipitated from a state of solution is an indication of the terrestrial origin of the rocks, which were laid down on the floors of the inland seas, separated more or less completely from the open ocean; for the waters of the ocean are capable of retaining in solution all of the material which is brought down to them, and accordingly precipitates of carbonate of lime, rock-salt, gypsum and other compounds formed from solution, are only formed on a large scale in inland lakes, though they may be formed to some extent when the water of a lagoon is only slightly connected with that of the open ocean, and the evaporation is great, for instance in the lagoons of coral reefs. certain physical features often mark the deposits of chemical origin, cubical or hopper-crystals of rock-salt may be dissolved, and the hollow afterwards filled with mud, so that the rock surfaces are sometimes marked with pseudomorphs of mud after rock-salt. sun-cracks and rain-prints impressed on the rock are not actual indications of terrestrial origin of the rocks on which they are found, for the shallow-water muds of an estuary may be deposited in the sea and yet exposed to the action of the air at low tide, but they mark very shallow-water deposits which have been exposed to the atmosphere immediately after their formation if not during the time they were formed, and they frequently occur amongst the deposits of inland lakes. it will be observed that the characters of the terrestrial accumulations serve to distinguish them to some extent from the marine ones, but they also enable one to detect to some degree the actual conditions under which the accumulation was produced, whether on the mountain-slope, or in the plain, the desert or the fen, the river-bank or the lake-floor. the conditions of formation of the marine deposits may be distinguished within certain limits with ease, by examination of their physical characters, for the near-shore deposits will generally be coarser and contain more mechanically-transported material than the sediments which accumulate at a greater distance from the shore, though it is not safe to infer that deposits are formed away from the shore on account of the absence of mechanically-transported sediments. in districts where the mechanically-transported material is rapidly deposited, organic deposits of great purity may form close to the coast-line; for instance, when the rivers of a country end in fjords, the mechanical sediments are deposited in the fjords, and the sea around the coast is free from this sediment, and there the organisms can build up deposits of great purity; and a similar thing may happen when the rivers on one side of a country have short courses, and do not carry down much sediment, which occurs when the watershed is near the coast. on the one hand, clay may be formed in considerable purity near the coast, where the supply of mud is so great that the organisms existing there can do little in the way of contribution to the mass of the deposit, or it may be formed on the other hand in great depths of the ocean, where the supply of sediment is extremely small, but where all the organic tests become dissolved; as the characters of the deep sea clays are mainly negative, a geologist examining the rocks of the geological column would have much difficulty in distinguishing a deep-water clay from a shallow-water one by its lithological characters only. in cases of difficulty, information of importance is likely to be furnished by examination of the relative thickness of equivalent deposits in adjoining areas, for if we find a mass of clay a few feet thick in one region represented by hundreds of feet of clay and limestone in another, the former mass probably accumulated slowly and at some distance from the land; again, the uniformity of lithological characters of a deposit over a very wide area is a possible indication of its formation away from land, but this is not a safe guide, for reasons which will eventually appear, unless it can be shown that the deposit is everywhere of the same age. a clue to climatic conditions is frequently furnished by the physical characters of accumulations, especially terrestrial ones. the accumulations containing a large percentage of hydrocarbons have probably been formed under fairly temperate and moist climatic conditions, whilst the existence of millet-seed sandstones associated with chemical deposits points to desert conditions and inland lakes, requiring a dry climate and probably a warm one. glaciated surfaces and glacial deposits of course indicate a low temperature. some geologists profess that occasionally they can even determine the direction of the prevailing winds during past periods, by examination of the character of ripple-marks, rain-pits and other features, though it is doubtful whether much reliance can be placed upon these obscure indications. useful as is the physical evidence supplied by deposits, as an index to the conditions under which they were formed, it is usually only supplementary to the evidence derived from a study of the fossils. fossils when present in the rocks, usually supply considerable information concerning the prevalent conditions during the deposition of the rocks. by them we can not only separate marine from terrestrial deposits, but also freshwater deposits from æolian accumulations; each kind of deposit will generally contain the remains of organisms which existed under the conditions prevalent in the area of formation of the rock, though it is of course a frequent thing for a terrestrial creature or plant to be washed into a freshwater area or into the sea. in an æolian deposit, the invertebrate remains may be those of any air-breathing forms, as insects, galley-worms, spiders, scorpions and molluscs. the land-molluscs are all univalve. of vertebrates, we may find the bones and teeth of amphibians, reptiles, birds and mammals. occasionally freshwater or even marine forms may be found in an æolian deposit, but they will be exceptional. marine shells are often blown amongst the sand-grains of the coastal dunes, and seagulls and other birds frequently carry marine organisms far inland. the creatures frequenting fresh water differ from those of the land and of the sea. the most abundant vertebrate remains will be those of fishes, and of the invertebrates we find mollusca preponderate. the variety of molluscs is not so great as in the case of marine faunas. the bivalves always possess two muscular scars on each valve (except adult _mulleria_); whilst many marine shells as the oyster have only one muscular scar on each valve. (see fig. .) [illustration: fig. . _a._ monomyary shell with one scar. _b._ dimyary shell with two scars.] these scars mark the attachment of the adductor muscles, for drawing the valves together, and the shells with only one impression on each valve are called _monomyary_, those with two impressions _dimyary_. the discovery of monomyary shells indicates with tolerable certainty the marine character of the deposit in which they are found, though their absence cannot be taken as proof of freshwater origin. the beaks or umbones of the bivalves are often corroded in freshwater deposits, as may be seen by examining shells of the common freshwater mussel. "all univalve shells of land and freshwater species, with the exception of _melanopsis_ and _achatina_, which has a slight indentation, have entire mouths; and this circumstance may often serve as a convenient rule for distinguishing freshwater from marine strata; since if any univalves occur of which the mouths are not entire, we may presume that the formation is marine[ ]." [footnote : lyell's _students' elements of geology_, second edition ( ), chap. iii. a good account of the differences between freshwater and marine organisms, from which some of the facts here cited are extracted, will be there found.] [illustration: fig. . _a._ holostomatous shell. _b._ siphonostomatous shell.] in fig. _a_ shows a freshwater shell (_vivipara_) with entire mouth, whilst _b_ exhibits the shell of a marine gastropod (_pleurotoma_) with a notched mouth. the entire-mouthed shells are called _holostomatous_ whilst those which are notched, the notch being often prolonged into a canal, are termed _siphonostomatous_. many groups of invertebrates are seldom or never found in fresh water. of exclusively or nearly exclusively marine creatures we may name the foraminifera, radiolaria, sponges with a hard framework, most hydrozoa which secrete hard parts, corals, echinoderms, cirripedes, king-crabs, locust-shrimps, most polyzoa, brachiopods, pteropods, heteropods, and cephalopods. of extinct groups, the graptolites and trilobites seem to have been entirely confined to the sea. in the modern and comparatively modern deposits, the forms frequently belong to existing genera, and we get fairly conclusive evidence of the conditions of deposit by determination of the genera. the terrestrial (including freshwater) molluscs have mostly a long range in time. we find pulmoniferous gastropods of living genera in the carboniferous period, one (_dendropupa_) belongs to a subgenus of the modern land-shell _pupa_, the other (_zonites_) to a subgenus of the snail group _helix_. many freshwater molluscs as _unio_, _cyclas_, and _physa_ are found amongst the secondary rocks, and give a clue to the origin of the deposits which contain them. many extinct genera are closely allied to modern genera, and their mode of existence may be assumed with fair certainty. with all these guides, we may sometimes be left in doubt as to the conditions of deposit when organisms are few in number; thus, it is yet a matter for discussion whether the old red sandstone and many of the deposits of the coal measures of britain were of freshwater or marine origin. in considering the possibility of fossils having been carried from land to water or _vice versa_, it will be remembered that generally speaking they are more readily transferred from a higher to a lower level, so we are more likely to find remains of land-animals and plants in fresh water or the sea, and relics of freshwater animals and plants in the sea, than of marine or freshwater animals and plants in land, or marine organisms in fresh water. river-gravels and lacustrine deposits are especially prone to contain a considerable intermixture of land-forms with those proper to the station. fossils supply much information concerning the depth and distance from land at which the deposits were laid down. when portions of the ocean-water have been separated to form inland lakes, the water becomes saltier than that of the open ocean, if the evaporation is greater than the supply of fresh water, and the life of the inland sea undergoes change under the unfavourable conditions set up. many forms disappear altogether, and those which survive tend to become stunted, and the shells of many of the mollusca are abnormally thin; the fauna of an inland sea though it may have abundance of individuals is apt to be characterised by paucity of species. turning now to the faunas of the open oceans, it is found that in addition to latitude, the distribution of organisms is affected by depth, and by the nature of the sea-floor, and accordingly we find different organisms in different areas; and in examining the same area the organisms inhabiting different depths are not all the same, and at the same depth some kinds of animals have different _stations_ from those of others, one creature being confined to a sandy floor, another to a muddy one, and so on[ ]. the oceans have been divided into _provinces_, each of which is more or less characterised by the possession of peculiar forms which are termed _endemic_, in contrast to the _sporadic_ forms which are widely distributed. in any area which is margined by a coast line, the molluscs are distributed in zones which were formerly classed as follows:--the _littoral_ zone between tide marks, the _laminarian_ zone from low water to fifteen fathoms, the _coralline_ zone between fifteen and fifty fathoms, and the _deep-sea coral_ zone from fifty fathoms to one hundred fathoms or more; this last depth was once supposed to mark the limit of the downward extension of marine life, but as the result of modern deep-sea soundings we know that organisms extend to a much greater depth, and the deep-sea fauna, owing to uniformity of conditions over wide areas, contains fewer endemic forms in proportion to the sporadic ones than the shallow-water[ ]. the deep-sea deposits entomb the remains of these deep-sea organisms and also of numerous _pelagic_ organisms which live upon the surface of the ocean, whose remains sink to the ocean-floor after death. amongst the deposits of the deeper parts of the ocean, we find many which are almost exclusively composed of the tests of foraminifera, radiolaria and pteropods, the spicules of sponges, and the frustules of diatoms; and accordingly the existence of foraminiferal, pteropodan, radiolarian, and diatomaceous oozes, amongst the strata of the geological column, has been taken by some as indicating the prevalence of deep-sea conditions during the formation of those deposits: as the purity of a calcareous ooze depends upon the absence of mechanical sediment, or volcanic dust, and as the component organisms of these oozes are pelagic forms which live near the continents as well as in the open oceans, the presence of calcareous oozes implies the existence of a _clear_ sea during their deposition but not necessarily of a deep one, for if the sea-area be far away from land masses, or if the sediment be strained off in fjords, calcareous oozes may be formed in shallow water. the existence of pure radiolarian or diatomaceous deposits is better evidence of deep water, for if they were formed in shallow water we should expect an intermixture of calcareous tests, whereas these are dissolved whilst sinking into the extreme depths of the ocean. as the deep-sea creatures are under very different conditions from those of shallower waters, we might expect marked structural differences between the deep and shallow-water creatures: one such difference has been emphasized, namely the occurrence of animals which are blind or have enormously developed eyes in the great depths of the sea, where the only light is due to phosphorescent organisms. this is well seen in the case of many recent crustacea, and has been noted by suess in the case of the trilobites of some beds which he accordingly infers to be of deep-water origin, and it is interesting to find that these creatures are found in deposits which give independent evidence of an open-water origin. the _Æglinæ_ of the ordovician strata are frequently furnished with enormous eyes, and they are often accompanied by blind trilobites, and in bohemia the blind and large-eyed forms are sometimes different species of the same genus, for instance _illænus_[ ]. [footnote : for an account of the distribution of one group of organisms see woodward, s. p., _a manual of the mollusca_, from which many of the following observations are taken.] [footnote : for an account of the deep-sea fauna, see hickson, s. j., _the fauna of the deep sea_, .] [footnote : suess, e., _das antlitz der erde_, ^{er}. bd., p. .] as one would naturally expect, the actual depth at which deposits were formed can generally be calculated with a greater degree of certainty amongst the newer rocks than amongst the older ones. in the case of the pliocene crags, the depth in fathoms may be confidently given. in the cretaceous rocks attempts have been made to give numerical estimates of the depths at which different accumulations were formed, but some differences of opinion have arisen in the case of these rocks. in the palæozoic rocks, only a rough idea of the general depth can usually be obtained, and no attempt to calculate the depth in fathoms is likely to be even approximately correct in the present state of our knowledge. the comminution of fossils has sometimes been taken as an indication of shallower water origin of the deposits which contain them, but although the hard parts of organisms in a broken condition have frequently been shattered by the action of the waves, they may also be broken at great depths by predaceous creatures, and in many instances the fracture is the result of earth-movements occurring subsequently to the formation of the deposits. turning now to the difference in organisms which results from difference of station, it will be sufficient to give a quotation from woodward's _manual of the mollusca_ as an illustration:--"in europe the characteristic genera of _rocky_ shores are _littorina_, _patella_, and _purpura_; of sandy beaches, _cardium_, _tellina_, _solen_; gravelly shores, _mytilus_; and on muddy shores, _lutraria_ and _pullastra_. on rocky coasts are also found many species of _haliotis_, _siphonaria_, _fissurella_, and _trochus_; they occur at various levels, some only at the high-water line, others in a middle zone, or at the verge of low-water. _cypræa_ and _conus_ shelter under coral-blocks, and _cerithium_, _terebra_, _natica_ and _pyramidella_ bury in sand at low-water, but may be found by tracing the marks of their long burrows (macgillivray)[ ]." [footnote : woodward, s. p., _a manual of the mollusca_, p. .] the geologist will naturally select sporadic forms rather than endemic ones in comparing the strata of different areas, but how far differences in faunas are the result of existence at different times, and how far they are due to difference of conditions affecting contemporaneous organisms can only be discovered as the result of accurate observation. the main points to be regarded when comparing the successive faunas of different regions have been noticed in this and the preceding chapters, and it has been shown that as the evidence is cumulative, it requires the collection of a large number of facts obtained by observation of the strata before accurate inferences can be drawn. the indications of climatic conditions furnished by organisms require some consideration. in the comparatively recent deposits it is not difficult to get some notion of the prevalent climatic conditions when the fossils belong to forms closely related to modern genera. the existence of the arctic birch and arctic willow, and of shells belonging to species now living north of the british isles, in deposits of comparatively recent date in britain would afford convincing evidence of the occurrence of colder climatic conditions than those which are now prevalent in the area, even if the evidence were not confirmed as it is, by physical proof of glaciation in deposits of the same age. nevertheless, even in these recent beds, we have a useful warning, by finding species of elephant and rhinoceros associated with northern forms like the lemming, glutton, and musk-ox. we know that the species of elephant and rhinoceros (the mammoth and woolly rhinoceros) were provided with thick coverings which would enable them to resist the severity of an arctic climate, but had not these coverings been found, we might have been puzzled by the association of forms whose nearest allies are sub-tropical with others of arctic character. as we go back in time and deal with earlier deposits, the ascertainment of the climatic conditions becomes more difficult, as the fossils mostly belong to extinct species, genera or even families. in these circumstances, it is very dangerous to draw conclusions as to climatic conditions from examination of a few forms, but when we find that plants and animals, terrestrial and marine forms, vertebrates and invertebrates alike point to the same conclusion, as in the london clay, where all the fossils belong to forms allied to those now living under sub-tropical conditions, the state of the climate may be inferred with considerable certainty[ ]. the character of the fossils must be taken into account rather than their size. there was a tendency amongst geologists to believe that large organisms probably indicate warm conditions. recent researches in arctic seas have dispelled this belief. marine algæ of enormous size are found in the cold seas, and the size of creatures, abundance of individuals and variety of forms in the arctic faunas of some regions is very noteworthy. in the kara sea, for instance, a variety of creatures were dredged up during the voyage of the vega, and baron nordenskjöld makes the following pertinent remarks about them: "for the science of our time, which so often places the origin of a northern form in the south, and _vice versa_, as the foundation of very wide theoretical conclusions, a knowledge of the types which can live by turns in nearly fresh water of a temperature of + °, and in water cooled down to - · ° and of nearly the same salinity as that of the mediterranean, must have a certain interest. the most remarkable were, according to dr stuxberg, the following: a species of mysis, _diastylis rathkei_ kr., _idothea entomon_ lin., _idothea sabinei_ kr., two species of lysianassida, _pontoporeia setosa_ stbrg., _halimedon brevicalcar_ goës, an annelid, a molgula, _yoldia intermedia_ m. sars, _yoldia_ (?) _arctica_ gray, and a solecurtus[ ]. "the temperatures were taken by a centigrade thermometer. again we read of the results of dredging off cape chelyuskin. "the yield of the trawling was extraordinarily abundant; large asterids, crinoids, sponges, holothuria, a gigantic sea-spider (pycnogonid), masses of worms, crustacea, etc. _it was the most abundant yield that the trawl-net at any one time brought up during the whole of our voyage round the coast of asia_, and this from the sea off the northern extremity of that continent[ ]." [footnote : for a discussion as to the value of plants as indices of climate see seward, a. c., sedgwick essay for .] [footnote : nordenskjöld, a. e., _the voyage of the vega_, vol. i. chap. iv.] [footnote : _ibid._ chap. vii.] amongst the marine invertebrates reef-building corals and mollusca perhaps furnish the best evidence of climatic conditions. the coral-reefs of the jurassic rocks with large gastropods and lamellibranchs clustered around them have been appealed to in proof of the existence of sub-tropical conditions during their formation; further back in time we find evidence of climate furnished by the fossils of the silurian rocks of the isle of gothland in the baltic sea. of these, lindström writes "_the fauna had a tropical character_. in consideration of the great numbers of pleurotomariae, trochi, turbinidae and the large pteropods the assumption of a tropical character of the fauna may seem justifiable[ ]." [footnote : lindström, g., _on the silurian gastropoda and pteropoda of gotland_, stockholm, , p. .] structure may give some indication of climate even though the organism is not allied to living species. the bark of trees in arctic regions is often thicker than in more temperate regions, and the leaves of arctic plants often have special characters to enable them to resist the long periods during which they are deprived of water, though the fact that desert-plants frequently shew similar modifications deprives this test of any particular value except as a means of corroborating conclusions reached from other evidence[ ]. the shells of arctic mollusca may become stunted, but this is not by any means universal, and the same result may be brought about by other abnormal conditions, as for instance the increase of salt in a water area by evaporation. [footnote : for an account of the modifications of the leaves of arctic plants, see warming, eug., _om grønlands vegetation_, meddelelser om grønland, th part, p. .] on the whole, an examination of the evidence available for ascertaining the character of climate by reference to included organisms, shews that inferences may be drawn within certain limits, but that the task is a difficult one not unaccompanied by danger, and every kind of available evidence derived from a study of physical phenomena and the included organisms should be utilised before any conclusion is drawn. the likelihood of accurate inference is increased by comparing the faunas of various areas; should they seem to indicate a progressive lowering of climate when passing from lower to higher latitudes, it is probable that the indication is correct. the student is referred to a paper by the late professor neumayr for an account of the existence of climatic zones during the mesozoic period[ ]. [footnote : neumayr, m., "ueber klimatische zonen während der jura- und kreidezeit," _denkschrift. der math.-naturwissensch. classe der k. akad. der wissenschaften_, bd. xlvii. vienna, .] chapter x. evidences of conditions under which strata were formed, continued. in the preceding chapter, attention was drawn to the indications as to conditions of deposition furnished by the sediments of any one locality, and only passing reference was made to variation in the nature of the sediments and their organic contents, when the deposits are traced laterally from place to place; some attention must now be paid to this matter. it is sometimes inferred that, whereas similarity of organisms is a dangerous guide in correlating the strata of two areas, accurate correlations may be made, if the deposits can be traced continuously through the intervening interval; no doubt the task is simplified when this can be done, but the continuity of deposit of one particular composition is no more proof of contemporaneity than the occurrence of the same fossils continuously through the interval, imbedded in strata of different character, indeed probably not so much so. the existence of widespread masses of conglomerate, which are not found as linear strips, but which extend in all directions, is in itself an indication of this; the oldhaven pebble bed for instance, in the tertiary rocks of the london basin, is very widely distributed. we cannot suppose that coastal conditions prevailed far away from the shore-line, and accordingly when a conglomerate occurs in a widespread sheet, and not in a linear strip, this is indicative that the deposit has not been formed continuously but that strip has been added to strip along an advancing or receding shore line, and if this happens with conglomerates, it must occur also in the case of other deposits. [illustration: fig. .] in fig. [ ] let _a_ represent a shore line of a continent which is undergoing gradual elevation. a deposit of pebbles _a_ will be formed against the coast, one of sand _b_ further away, then one of mud _c_ and lastly limestone _d_, may be formed in the open sea away from land. naturally there may be intermingling of two kinds of deposit at the junctions, but for the sake of simplicity this may be disregarded. during the accumulation of the deposits _a_, _b_, _c_, _d_, certain sporadic forms may be distributed throughout all the deposits, and some of them may become extinct before the deposition of these beds is completed, if the process is carried out on a large scale; we may speak of the characteristic fossils of this period as fauna i. as the result of elevation or of mere silting up of the sea-margin, or of both combined, the next mass of pebble-deposit will be laid down further away from the original shore, for the shore line will now be at _a´_ and not at _a_, and it will partly overlap the mass of sand _b_; the sand _b_^ will also be deposited somewhat further out and partly overlap the mud _c_, and similarly the mud _c_^{ } will partly overlie the limestone _d_. during the formation of _a_^{ }, _b_^{ }, _c_^{ }, _d_^{ }, other sporadic forms belonging to a fauna ii may replace those of the first fauna. in the same way _a_^{ }, _b_^{ }, _c_^{ }, _d_^{ } will be deposited, and in the meantime a new fauna iii may arise and replace ii. so the process will go on until we finally have a group of deposits lying one over the other, consisting of a basal accumulation of limestone, succeeded by mud, sandstone and pebble-beds in succession. each of these will be continuous, though the inner part of the pebble-deposit was formed long before the outer part of the limestone, which is nevertheless beneath a mass of pebble-deposit continuous with that formed first, and the various deposits will be separated by fairly horizontal planes _x_, _y_, _z_, which might be regarded as bedding planes, but which are not so, strictly speaking. the true bedding planes will occur at a slight angle to these planes of separation, for the structure resembles false bedding on a gigantic scale, but of course, the lines separating two masses of similar deposit will be practically horizontal and parallel to the planes of demarcation of two distinct kinds of material. the lines separating two faunas would, under the conditions postulated, run approximately parallel to the planes of separation of adjoining deposits of the same lithological character but would pass from conglomerate, through sandstone, mud and limestone, as indicated by the lines , , , ... and the deposits between adjoining lines would be contemporaneous[ ]. in nature, complications will arise, owing to the gradual appearance and disappearance of forms, and the existence of endemic species in contemporaneous deposits formed in different stations and having different lithological characters. [footnote : the writer gratefully acknowledges his indebtedness to prof. lapworth for some of his views concerning deposition of strata.] [footnote : the lines , , ... are incorrectly drawn in the figure. line should be drawn so as to separate _a_, _b_, _c_, _d_ from _a_^{ }, _b_^{ }, _c_^{ }, _d_^{ }, line to separate _a_^{ }, _b_^{ }, _c_^{ }, _d_^{ } from _a_^{ }, _b_^{ }, _c_^{ }, _d_^{ }, and so with the others.] if elevation ceased and were succeeded by depression, the exact opposite would occur, and the pebble beds would be overlain by sandstones, these by muds, and lastly limestones would appear. it follows that during a marine phase occurring between two unconformities we should have a =v=-shaped accumulation of deposits with the apex pointing to the part of the shore line which was last submerged before the commencement of elevation, as shewn in fig. , though the beds of the apex will in most cases be denuded during the re-emergence. [illustration: fig. .] indications of the non-coincidence of the planes separating faunas and those which separate deposits of one lithological character from those of another have already been detected, for instance the 'greensand' condition of the cretaceous period occurs in some places during the existence of one fauna, and in others during that of another, though the planes have not been traced continuously. mr lamplugh has furnished another example amongst the cretaceous rocks of yorkshire and lincolnshire, but as has already been observed, a great deal remains to be done in this direction, and geologists are much in want of two sets of stratigraphical maps, in one of which the lines are drawn with reference to the differences of lithological character, whilst in the other they separate different faunas. the student will notice the normal recurrence of deposits in definite order; conglomerate succeeded by sandstone, mud and limestone, in a sinking area, and limestone succeeded by mud, sandstone and conglomerate in a rising area. naturally many instances of departure from this rule are seen, owing to local conditions, but on a large scale, it is very frequently noted, and recognition of this will enable the student to remember the variations in the lithological characters of the deposits more easily, than if he simply acquired them from a text-book without taking heed as to their significance. upon the variations in the lithological characters of deposits and of their faunas, when the beds are traced laterally depends very largely the successful ascertainment of the existence of former coast-lines, the restoration of which constitutes an important part, of palæo-physiography, concerning which some observations may here be made[ ]. if a set of deposits having different lithological characters can be proved to be contemporaneous, the coarser detrital accumulations will point to the approach to a coast-line, and the actual position of the coast during the period of accumulation of the deposits may be very accurately fixed. the pebble-beds at the base of the cambrian rocks of llanberis indicate the existence of a coast-line in that position during the accumulation of those pebble-beds. similar pebble-beds occur at st david's, at the base of the cambrian, but it is impossible in the case of these rapidly accumulated sediments to say that two deposited so far away from one another were actually contemporaneous, and therefore although we might draw a line through llanberis and st david's to indicate the old coast-line of the period, it does not follow that the actual beach existed simultaneously at the positions indicated. the palæo-physiographer, however, attempts to restore the physical conditions of greater thicknesses of deposit; for instance, the distribution of land and sea during lower carboniferous times over the area now occupied by the british isles is often taken to illustrate the methods of restoration of ancient features, and all admit that the lithological and palæontological characters of the rocks indicate a shallowing of the carboniferous sea when passing northwards towards scotland. for conveying an idea of the restorations to the student, it is almost imperative to portray the distribution of land and sea upon a map, and this can only be done by drawing definite lines. it must be distinctly understood that these lines are necessarily only an approximation to the actual position of the ancient shore-lines, which must have shifted again and again during the long period occupied by the accumulation of the lower carboniferous strata, so that a true idea of the positions of the lower carboniferous shore-lines could only be obtained by placing on a series of maps the successive shore-lines of different parts of the lower carboniferous period, and taking a composite photograph of these, which would appear as a wide belt of shaded portion of the map with no definite boundaries. the utmost that the maker of palæo-physiographical maps can expect to indicate, when dealing with considerable thicknesses of strata, is an approximation to the mean position of the shore-lines of the period when these strata were deposited. this is extremely valuable in enabling the student to understand the significance of the variations in the characters of the strata and their organic contents, if he distinctly recognises the generalised nature of the map. examination of any two palæo-physiographical maps of the same period by different authors will shew wide divergences in the details, but a general resemblance of the main features. the reader will do well to consult prof. hull's restoration of the physical features of old red sandstone and lower carboniferous times on plate vi. of his _contributions to the physical history of the british isles_, and compare it with the map drawn by prof. green (_coal: its history and uses_, by profs. green, miall, thorpe, rücker, and marshall, fig. , p. ), which will be found to bear out this statement. [footnote : on this subject, the student may consult prof. e. hull's _contributions to the physical history of the british isles_.] valuable as the published maps of palæo-physiography are as an aid to the student in understanding the significance of the variations of characters amongst the sediments, he will do well to supplement them by maps which he fills in for himself. he is recommended to procure a number of outline maps of england, or of the british isles, and when studying in detail the characters of the british sedimentary rocks formed during the various periods, to place a blank map by his side when beginning the study of each period or important portion of a period. on this map he should jot down the geographical distribution of the different kinds of sediments, using the conventional signs indicated at p. : thus, in the case of the lower carboniferous rocks he would place the conventional sign for limestone in derbyshire, a combination of those for limestone and shale in yorkshire, and would add to these the sandstone sign in northumberland. he should also note the general character of the fossils, using abbreviations for such terms as fresh-water fossils, shallow-sea fossils, deep-water fossils. after reading the account of the group of rocks in a comprehensive text-book, and inserting his notes on the map, he should proceed to insert the probable position of the coast-lines. he should also take notes of any indications of contemporaneous volcanic action, though these might well be inserted on a separate map. if this course be pursued, the student will not only have the significance of the variations amongst the strata impressed upon his mind, but he will have a means of obtaining at a glance the distribution of sediments and faunas of different kinds in the british area during the principal geological periods. on another set of maps he may indicate the axes of the orogenic movements which have occurred at different times, and when his various maps are completed, he will have the materials for the construction of a general account of the various geological processes which have been concerned with the building of the british area. when an area like britain has been studied, the student may proceed to construction of maps of wider regions, and he will find that in doing this, new sets of facts must be taken into consideration, as for instance the occurrence of different faunas on opposite sides of once-existing continental masses, and the problems connected with the present distribution of the faunas and floras. for an instance of the importance of the former distribution of life the reader may consult the twelfth section of the first part of professor suess' _das antlitz der erde_, whilst a good account of the value of recent geographical distribution of organisms in supplying a clue to former distribution of land and sea will be found in mr a. r. wallace's _island life_, chapter xxii. should the method suggested above be adopted, the student is likely to acquire a much more coherent idea of the significance of the facts of stratigraphical geology than can be obtained by a mere perusal of the accounts of the strata given in those portions of the various text-books which are devoted to a consideration of the stratigraphical branch of the science. chapter xi. the classification of the stratified rocks. in the succeeding chapters, a general account of the characters of the geological deposits of different periods will be given, for the purposes of illustrating the principles to the consideration of which the earlier chapters have been devoted. it is not proposed to enter into a description of numberless details, which would only confuse the student who wished to grasp the main principles, for many facts have been recorded which it is necessary to notice in a comprehensive text-book treating of stratigraphical geology, though their full significance is not yet grasped. the writer, while noting the main characters of the various subdivisions of the different stratigraphical systems, will assume that this work is used in conjunction with some recognised text-book. the stratigraphical portion of sir a. geikie's _class book of geology_ gives an admirable general account of the british strata, while the larger text-book by the same author has a condensed though very full account of the rocks of the stratigraphical column in all parts of the world, and this is supplemented by numerous references to the original works wherein further descriptions may be found. the english edition of prof. e. kayser's _text-book of comparative geology_, edited by p. lake, is also well adapted to the wants of the student, and an excellent account of the strata is given in mr a. j. jukes-browne's _handbook of historical geology_, which may be read with the same author's _building of the british isles_. the reader who refers to different text-books will be struck with the variations of nomenclature even amongst the larger stratigraphical divisions, for two authors seldom subdivide the geological column into the same number of rock-systems. the following classification will be here adopted:-- groups. systems. { recent { pleistocene cainozoic or { pliocene tertiary { miocene { oligocene { eocene { cretaceous mesozoic or { jurassic secondary { triassic { permian { permo-carboniferous { carboniferous palæozoic { devonian { silurian { ordovician { cambrian. precambrian. a few remarks may be given as to the reason for adopting this classification. it is not for a moment suggested that the systems have the same value, if the time taken for their accumulation be alone considered. the beds classified as recent, for example, were probably accumulated during a lapse of time far shorter than that occupied for the deposit of some of the series or even stages of a system like the silurian, but the recent rocks acquire a special significance from the fact that we are living in the period, and the cainozoic rocks as a whole are capable of greater subdivision than the earlier groups, on account of the greater ease with which they can be studied, owing to the small amount of disturbance which they have usually undergone when compared with that which has affected older rocks, and the closer resemblance of their faunas and floras to those of existing times. with reference to the groups, the writer has already commented upon the use of the terms palæozoic, mesozoic and cainozoic; below the lowest palæozoic rocks (those of the cambrian system) lie a group of rocks which have been variously spoken of as azoic, eozoic, and archæan. there is an objection to the use of any one of these words in this sense; the objection in the case of the first two is that the term is theoretical and probably incorrect, whilst the word archæan, otherwise suitable, has also been used in a more restricted sense. in these circumstances the term precambrian will be used when referring to any rocks which were formed below palæozoic times, though no doubt when this obscure group of rocks is more thoroughly understood a satisfactory classification will be applied to it. taking the other groups into account, the lower systems of the palæozoic group will be found to vary greatly according to the views of different writers; some make only one system, the silurian, others two, the cambrian and silurian. the three systems are here adopted, not only because the one, silurian, is too unwieldy on account of its size and requires subdivision (and the cambrian and silurian however defined, will be found to be of very unequal importance, whereas the three systems adopted are of fairly equal value), but especially because when the term ordovician is used, the significance of the other terms cambrian and silurian is at once understood. an attempt has been made to shew that the devonian system is non-existent, but the result of modern research is to shew that the rocks placed in this system are worthy of the distinction, both from their importance and from the distinctness of the fauna from those of the underlying and overlying systems. the permo-carboniferous system is adopted, because an important group of deposits has recently been brought to light which were not represented either in the permian or carboniferous system as originally defined. some authors have advocated the union of the permian and triassic systems into one system placed at the base of the mesozoic group. this is unnecessary, and would depart from the classification originally proposed, which is to be deprecated, unless there is any strong reason for it. the mesozoic systems are classified according to the method generally adopted. were a fresh classification to be proposed, a portion of the cretaceous system might be included with the jurassic rocks, but it is better to adhere to the old classification. the divisions of the cainozoic rocks are hardly systems in the sense in which the term is used in the case of the older rocks, but the reason for using these smaller subdivisions has already been mentioned. the addition of the oligocene to the original divisions suggested by lyell has been found useful, and the term will be used in this work. the reasons for the adoption of the particular minor subdivisions (series and stages) in the following chapters will frequently appear when the rocks of the various systems are described, and need not be further alluded to in this place. although most geologists describe the stratified rocks in ascending sequence beginning with the oldest, and proceeding towards the newest, others, and notably lyell, adopted the opposite method and commenced with an account of the newest beds. the argument generally used for the latter method is that it is easier to work from the study of the known to that of the less known, and as the faunas of the newest rocks are most like the existing faunas, the student would more readily follow a description of the rocks in the order which is opposite to that in which they were deposited. in practice, the study of the sediments in their proper order, that is, in the order of deposit, will not be found to task the student to any great extent, especially if, as is very desirable, he has studied the main facts and principles of palæontology before commencing the study of the rock-systems in detail. there is one reason for beginning with the study of the older sediments which outweighs any reasons which can be advanced against it, namely that the events of any period produce their effect not only upon the strata of that period, but also on those of succeeding periods. the task of the stratigraphical geologist is really to learn the evolution of the earth, in its changes from the simple to the more complex conditions, and it is quite obvious that it is unnatural to attempt any study of evolution by working backward. for this reason the study of the sediments will be here made in the order which is usually adopted, by passing from the older to the newer, and from the simple to the more complex. the british strata will be mainly considered, though references will frequently be made to their foreign equivalents, and a fuller account of the latter will be added when the british strata are abnormal, as are those of triassic times, and also when a period is not represented amongst the strata of the british isles, as for instance, the permo-carboniferous and miocene periods. the student is recommended to refer constantly to good geological maps of the british isles, of europe, and of the world. of maps of the british isles, mention may be made of sir a. ramsay's geological map of england, sir a. geikie's map of scotland, and his map of the british isles, j. g. goodchild's map of england and wales, a map of europe by w. topley and one of the world reduced from that by j. marcou, accompanying the first and second volumes of the late sir j. prestwich's _geology_. for special purposes more detailed maps will be studied, including the one-inch maps of h. m. geological survey, and the index map on a smaller scale. lastly, for an account of british geology, reference must be made to h. b. woodward's _geology of england and wales_, where the british formations are described in order, and to w. j. harrison's _geology of the counties of england and wales_, where the stratigraphical geology of the country is given under the head of the different counties, which are taken in alphabetical order. in concluding this chapter, it is hardly necessary to say that every opportunity of studying the characters of the deposits and their fossils in the field should be eagerly seized, and that much information may be acquired even on a railway journey, especially as to the influence which the deposits exert upon the scenery of a region[ ]. [footnote : in the first edition of h. b. woodward's _geology of england and wales_, an account of the geology of the main lines of english railways is given, which is omitted in the later edition. it is well worth consulting by those who take a long journey, and it will be found useful to take a geological map with one on the journey so as to discover when one is passing from one formation to another.] chapter xii. the precambrian rocks. study of a geological map of the world will shew that extensive regions, such as parts of scandinavia, many tracts of central europe, a large area in canada, and a considerable portion of brazil and the adjoining countries are occupied by crystalline schists, which underlie the oldest known sedimentary strata in those places. these crystalline schists form the floor upon which the sediments constituting the bulk of the geological column rest, and it is necessary that we should know something of the character of this floor. other rocks which can be definitely proved to be of precambrian age are often found associated with the crystalline schists, and these associated rocks have often undergone more or less alteration subsequently to their formation. the difference between the coarser types of crystalline schists and these associated rocks is sometimes so marked that geologists have necessarily paid attention to it, and separated the two groups of rocks; the term archæan has been used by some geologists to include the crystalline schists, and eparchæan for the associated rocks of known precambrian age, but though this separation may sometimes be effected, there are cases when it is impossible to draw any sharp line of demarcation between 'archæan' and 'eparchæan' types. in the present state of our knowledge, a chronological classification of the precambrian rocks when applied to wide and distant regions is destined to break down, and it will be convenient if we consider at some length the features of the precambrian rocks of a particular region, and apply the knowledge thus gained to a study of precambrian rocks of other areas, and to a consideration of our knowledge of the precambrian rocks as a whole. in doing so, the term 'crystalline schists' will be used somewhat vaguely with reference to a complex of schistose rocks of which the mode of origin cannot be fully determined. we may take our own country as a region where a good development of the precambrian rocks occurs. a few explanatory remarks concerning the mode of detection of precambrian rocks may not be amiss. if any true organisms have been hitherto discovered amongst the rocks formed before cambrian times they are valueless as a means of correlating rocks, and accordingly lithological characters only are available in attempting to correlate the rocks of one area with those of another. those who have read the preceding chapters will have gathered that comparisons founded on similarity of lithological character are not so valuable as those made after careful scrutiny of the fossils of strata, but they are by no means valueless, and when the rocks of two areas which are not far distant from one another present close lithological resemblances, their general contemporaneity may be inferred with some degree of certainty. it is only when we get the lowest cambrian strata overlying earlier rocks that we have absolute proof of the precambrian age of the latter, and it is necessary, therefore, that we should have some definite lower limit to the rocks of the cambrian system. it is now generally agreed that that limit shall be drawn at the base of a group of rocks containing what is known as the _olenellus_-fauna, which will be considered at greater length in the next chapter, and it will be well, if the term cambrian be not in future applied to any rocks beneath the ones containing the relics of this fauna, for otherwise there is danger of the indefinite downward extension of the cambrian system. we need not be surprised to find great thicknesses of rock below the rocks containing the _olenellus_-fauna, and passing upwards with complete conformity into those rocks; nevertheless, if it can be shewn that the _olenellus_-fauna had not appeared during the deposition of the underlying group, the rocks of that group should be termed precambrian. a case of this nature has not yet been detected in our area, and all the rocks which have been proved to be precambrian in britain are separated from the overlying cambrian rocks by a physical break, though that break is not necessarily very large, and in some districts is probably of little importance. hitherto the _olenellus_-fauna has been detected in ross, warwickshire, shropshire, worcestershire and probably in pembrokeshire, and the rocks underlying the _olenellus_-beds in those counties can be proved to be precambrian (i.e. if the _olenellus_-age of the pembrokeshire rocks be ultimately established, and the researches of dr hicks tend to prove that it will almost certainly be done). it will be convenient if we take the instances where the age of the rocks can be proved with certainty or with a considerable degree of probability first, and then consider the examples of rocks which are found below cambrian strata, though these have not hitherto yielded the _olenellus_-fauna, concluding with a notice of rocks which have been claimed to be of precambrian age on account of their lithological characters, though they are not now seen to be immediately succeeded by strata appertaining to the cambrian system. commencing with the region where we have the greatest development of the known precambrian rocks, namely ross, sutherland and the hebrides, we may explain the general relationship of the rocks by means of a generalised section (fig. ). [illustration: fig. .] the lowest rocks _a_ are crystalline schists, they are succeeded by a set of arenaceous rocks _b_ known as the torridonian beds, which rest unconformably upon the upturned edges of the crystalline schists, whilst the cambrian rocks, _c_, rest with another unconformity sometimes upon the partly denuded torridonian beds, or where the latter have been completely removed, as on the right side of the figure, directly upon the crystalline schists, thus presenting an example of unconformable overlap. the occurrence of the _olenellus_-fauna in the basement beds of the cambrian system near loch maree, proves the precambrian age of the torridonian strata, whilst the unconformable junction between the latter and the crystalline schists indicates that we are here dealing with two distinct sets of precambrian rocks, one of eparchæan and the other of archæan type. the crystalline schists consist of rocks of very varied lithological characters, some with gneissose, and others with schistose structure, and they vary in degree of acidity from ultrabasic rocks to those of acid composition. most of them exhibit parallel structures, which in many cases can be shewn to have been impressed on the rocks subsequently to their consolidation, though this need not have occurred and probably did not occur with some of them, especially the granitoid gneisses. the researches of the members of h. m. geological survey have shewn that many of these rocks were originally intrusive igneous rocks, though it is not yet known into what rocks those which were first consolidated were injected, and the origin of the bulk of the schists still remains to be elucidated. subsequently to their consolidation and before the deposition of the earliest torridonian rocks they were subjected to more than one set of earth-movements, which folded them and impressed a series of parallel structures upon many of them; and accordingly we find that the pebbles of the crystalline schists which are found amongst the basal conglomerates of the torridonian rocks consist of fragments which had undergone the alteration caused by these earth-movements before they were denuded from their parent-rocks[ ]. [footnote : for an account of these rocks, their characters, and the effects of earth movement upon them, the reader should consult a "report on the recent work of the geological survey in the north-west highlands of scotland": _quart. journ. geol. soc._, vol. xliv. p. .] the torridonian system is composed of rocks which are largely of arenaceous character, the most prominent beds being formed of red sandstones, and the bulk of the fragments in them have clearly been derived by denudation from the crystalline schists, many of the beds being composed of arkose, where the quartz is mixed with a large proportion of felspar and often of ferro-magnesian minerals. the deposits are clearly sedimentary, and are as little altered as many strata of much more recent origin, only possessing structures produced by metamorphic action under exceptional circumstances. the detailed researches of the geological surveyors prove that the rocks of this system have a much greater thickness and are of more varied lithological characters than was previously supposed. the total thickness of the strata is over , feet, and the sandstones are associated with deposits of a muddy character, and with occasional bands of limestone; in these circumstances the discovery of fossils would excite no surprise, and in sir a. geikie announced the detection of "traces of annelids and some more obscure remains of other organisms in these strata," which have not yet been described[ ]. these torridonian strata furnish us with the most satisfactory group of precambrian sediments yet detected in britain[ ]. [footnote : an account of the subdivisions and lithological characters of the rocks of the torridonian system will be found in the _annual report of the geological survey of the united kingdom_ for .] [footnote : it has been recently maintained that some of the torridonian rocks are of Æolian origin.] in the south-east highlands is a great mass of crystalline schists of a less gneissose character than that of the north-west, to which sir a. geikie has applied the name dalradian. many of these schists will be found by examination of the geological map of scotland to be separable into divisions, which by means of their lithological characters can be traced long distances across the country, and they present all the characters of sedimentary rocks, though they are associated with intrusive igneous rocks, and have undergone great metamorphic changes since their formation. cambrian rocks have not yet been discovered immediately above them, though they are clearly older than ordovician times, but the existence of rocks associated with them along their north-west borders, which in lithological characters closely resemble some of the rocks of the crystalline schists of the north-west highlands, indicates the probability of their general precambrian age. in some instances, the extreme types of metamorphism which they exhibit are the result of the kind of action usually termed pyrometamorphic as has been shewn by mr g. barrow[ ]. [footnote : barrow, g. "on an intrusion of muscovite-biotite gneiss in the s.e. highlands of scotland, and its accompanying metamorphism." _quart. journ. geol. soc._, vol. xlix. p. .] in england and wales the rocks which have been shewn or inferred to be precambrian, when not intrusive, are largely of volcanic origin. the most satisfactory example of the occurrence of the _olenellus_-fauna is that of the cambrian comley sandstone of shropshire, which rests unconformably upon a set of rocks termed by dr callaway the uriconian rocks; the latter are essentially volcanic, and strongly resemble precambrian rocks of other british areas. there is also strong reason to suppose that the sediments to which the name longmyndian has been applied, which have been described by the rev. j. f. blake, are of precambrian age, for, as professor lapworth has pointed out, the three great subdivisions of the cambrian system are present in the area under consideration, and the rocks of each are entirely different from those of the adjoining longmynd area. in shropshire therefore we meet with one set of volcanic rocks, and another set consisting of sedimentary rocks, of which the former is certainly, the latter almost certainly of precambrian age, and as the longmyndian rocks are in a comparatively unaltered condition, consisting of normal sediments, we may well expect the discovery of fossils in them also[ ]. the _olenellus_-fauna has been found near nuneaton in warwickshire in beds which unconformably succeed volcanic rocks, the caldecote series of prof. lapworth, and the latter are therefore of precambrian age[ ]. a few fossils belonging to the _olenellus_-fauna have occurred in the oldest cambrian rocks of the malvern district, and these rocks rest unconformably upon those of an old ridge which is therefore composed of precambrian rocks. the rocks of this ridge are largely of intrusive igneous origin, though parallel structures have been impressed upon them as the result of subsequent deformation, but some of the rocks are almost certainly of contemporaneous volcanic origin[ ]. in the wrekin ridge, igneous and pyroclastic rocks are found succeeded unconformably by cambrian rocks which resemble those of the malvern and nuneaton districts, and probably belong to the period of existence of the _olenellus_-fauna, and these igneous and pyroclastic rocks are presumably of precambrian age, and the contemporaneous rocks constitute dr callaway's typical uriconian group. volcanic ashes and breccias are accompanied by devitrified pitchstones and intruded granitic rocks, which may or may not be all of the same general age[ ]. the rocks which have been claimed as precambrian in pembrokeshire and in caernarvonshire have the same general characters as those of the wrekin ridge. pyroclastic rocks underlie the oldest cambrian rocks, with discordance between the two, and associated with these pyroclastic rocks are quartz felsites which according to some are of contemporaneous nature whilst others maintain their intrusive origin. in each county granites are found which are now generally recognised to be intrusive, though there seems to be no doubt as to their being of the same general age as the rocks with which they are associated, and therefore presumably precambrian. the pembrokeshire rocks are marked by the occurrence of a certain amount of metamorphism, probably of more than one kind, which has converted pyroclastic volcanic rocks into sericitic-schists and quartz-felsites into hälleflintas[ ]. the term pebidian given by dr hicks to the contemporaneous volcanic fragmental rocks should be retained, and if these rocks be eventually shewn to be contemporaneous with similar volcanic rocks of other districts, may be applied generally, as it has priority over other terms as uriconian and caldecote series. the term dimetian was applied to rocks known to be intrusive, and must be dropped as a chronological term, whilst the existence of an arvonian system separate from the pebidian system is not fully proved. [footnote : the reader may consult a paper by prof. lapworth "on _olenellus callavei_ and its geological relationships," _geol. mag._ dec iii. vol. viii. p. , for information concerning the relationship of the _olenellus_ beds of shropshire to the more ancient rocks; the uriconian rocks are described by dr callaway in a series of papers, especially in the _quarterly journal of the geological society_, vol. xxxv. p. , vol. xxxviii. p. , vol. xlii. p. and vol. xlvii. p. , whilst the lithological characters of the longmyndian rocks are described by the rev. j. f. blake (_quart. journ. geol. soc._, vol. xlvi. p. ).] [footnote : see lapworth, c., "on the sequence and systematic position of the cambrian rocks of nuneaton," _geol. mag._ dec iii. vol. iii. p. ; and waller, t. h., "preliminary note on the volcanic and associated rocks of the neighbourhood of nuneaton," _ibid._ p. .] [footnote : for details concerning the rocks of the malvern hills see papers by callaway in the _quarterly journal of the geological society_, vol. xxxvi. p. , xliii. p. , xlv. p. , and xlix. p. , and a paper by prof. a. h. green, _ibid._ vol. lvi. p. .] [footnote : callaway, c., _quart. journ. geol. soc._, vol. xxxv. p. .] [footnote : the pembrokeshire area is of interest as the probable existence of precambrian rocks in britain was first indicated on good evidence in this county. the general structure of the district is fairly simple, consisting of cambrian rocks beneath which precambrian rocks are exposed in at least two ridges of which the northerly and more important one runs through st davids. the rocks of the st davids ridge consist of a binary granite (granitoidite), felsites, and volcanic ashes and breccias of intermediate composition. much diversity of opinion has existed, and to some extent still exists as to questions of detail, and a very extensive literature has been devoted to these rocks. amongst the numerous papers which treat of them, the student may consult the following:--hicks, h., _quart. journ. geol. soc._, vol. xxxiii. p. , xxxiv. p. , xxxv. p. , xl. p. , xlii. p. , geikie, a., _ibid._ vol. xxxiv. p. , blake, j. f., _ibid._ vol. xl. p. , and morgan, c. ll., _ibid._ vol. xlvi. p. . much of the matter contained in these papers is controversial, and need not be fully read by those who merely wish to obtain a general account of the rocks of the district.] in caernarvonshire two ridges are found, the one running from bangor to caernarvon, and the other through llanberis lake. the rocks of these are generally similar to those of st davids, and as the lowest cambrian rocks of the area closely resemble those of st davids, the precambrian age of the rocks of these ridges is rendered highly probable, though until the discovery of the _olenellus_-fauna in the area, it cannot be regarded as proved[ ]. [footnote : these rocks are described by t. m^{c}k. hughes, _quart. journ. geol. soc._, vol. xxxiv. p. , and xxxv. p. ; by prof. t. g. bonney, _ibid._ vol. xxxiv. p. ; and by dr hicks, _ibid._ vol. xxxv. p. .] the actual position of the similar rocks of anglesey has not been so clearly fixed, as the rocks associated with them are of ordovician age, but their resemblance to the rocks of the adjoining regions renders their precambrian age highly probable. it is interesting to find in association with the rocks which resemble those of caernarvonshire, others which sir a. geikie recognises as quite similar to some existing amongst the crystalline schists of the north-west highlands of scotland, and when these ancient rocks of anglesey have been mapped in detail, they will probably be found to present greater variety than is afforded by any precambrian rocks of great britain occurring s. of the scotch border[ ]. [footnote : papers upon the old rocks of anglesey will be found in many volumes of the _quarterly journal of the geological society_; see especially hicks, vol. xxxv. p. , callaway, vol. xxxvi. p. , xxxvii. p. , and blake, xliv. p. .] of rocks whose age is more uncertain, but which are probably of precambrian age, those of charnwood forest in leicestershire may first be noticed. they are largely of pyroclastic origin, and from their likeness to similar rocks of proved precambrian age, they are very probably of this age, as suggested by messrs hill and bonney[ ]. a group of crystalline schists is found in the south of cornwall, especially near the lizard, and similar rocks are found in the channel isles. as their relationship to newer rocks is not clear, little can be said about them, which has not already been noticed in mentioning the crystalline schists of other regions[ ]. [footnote : hill and bonney, _quart. journ. geol. soc._, vol. xxxiii. p. , xxxiv. p. and xlvii. p. ; see also watts, w. w., _rep. brit. assoc._ for , p. .] [footnote : for an account of the volcanic history of britain in precambrian times, see sir a. geikie, presidential address to the geological society, _quart. journ. geol. soc._, vol. xlvii. p. .] the precambrian rocks of the european continent consist largely of crystalline schists which in their general aspects recall those of the north-west highlands of scotland. important masses are found in bavaria, bohemia, france, spain, scandinavia and russia. the scandinavian and russian rocks of archæan type are in places succeeded by the _olenellus_-bearing beds of the cambrian rocks, and rocks of eparchæan character are not extensively developed, though certain norwegian rocks may be the equivalents of the torridonian rocks of scotland, and other rocks of this type are found in places in sweden. in bohemia and in brittany precambrian strata of eparchæan type have been discovered, and this type probably occurs elsewhere in europe. the north american rocks require some notice, for it was in canada that the existence of precambrian rocks was first recognised, and the term laurentian, originally applied to an archæan type of precambrian rocks in canada, was subsequently adopted in speaking of many precambrian rocks elsewhere, though it is now wisely restricted to the type of rock in the original area to which the name was first given. these laurentian rocks acquired a special, interest on account of the occurrence in their limestones of a supposed reef-building foraminifer, _eozoon canadense_, but detailed study of its structure and mode of occurrence has convinced most geologists that the structure is inorganic. the laurentian rocks of the typical laurentide region are largely crystalline schists associated with massive crystalline rocks. the attempt to separate them chronologically into a lower and upper division was premature, as shewn by the fact that many of them, upon detailed study, prove to be intrusive igneous rocks. in the neighbourhood of lake huron, a set of sedimentary rocks overlying the archæan rocks is of eparchæan type, consisting to a great extent of volcanic rocks, clay-slates and schists with intrusive igneous rocks; it has been termed the huronian system, and this term has also been extensively applied to other eparchæan types found elsewhere, but should be restricted to the rocks of the huron district. a number of other rocks of eparchæan type have been discovered in various parts of north america, and have been grouped together under the title of algonkian, a name proposed for them by dr c. d. walcott, and an attempt has been made to arrange them in chronological order, though in the absence of fossils, the rocks of different districts can only be so arranged by reference to lithological characters; nevertheless a detailed study of the eparchæan and some of the more finely crystalline schistose rocks points to the existence of a number of divisions of sedimentary rocks of precambrian age, some of which may attain to the dignity of forming separate systems[ ]. by far the most instructive development of american precambrian rocks has been found in the rainy lake region of canada, and it is the subject of a special memoir by dr a. c. lawson[ ]. the archæan rocks of the region are divided into a lower laurentian and an upper division, which is further subdivided into the coutchiching series below and the keewatin series above, though the rocks of the keewatin series are largely of eparchæan character. the laurentian rocks of this region resemble those of the laurentide area, and consist of highly crystalline schistose and gneissose rocks associated with compact rocks. the coutchiching series consists of mica schists and grey laminated gneisses, which appear to have been of sedimentary origin, altered by subsequent metamorphic action, while the keewatin series, which reposes sometimes upon the rocks of the coutchiching series (when the junction is an unconformable one), sometimes upon the laurentian rocks, is formed of pyroclastic rocks and lava flows with intercalated sedimentary rocks; some of the keewatin rocks are highly metamorphosed but others have undergone little or no metamorphic change. the most important point in connexion with these rocks of the rainy lake region has reference to the relationship between the laurentian rocks and those of the coutchiching and keewatin series. lawson demonstrates the igneous nature of the laurentian rocks, and brings forward evidence of various kinds that they were formed "by the fusion of the basement or floor upon which the formations of the upper division of the archæan were originally deposited. with the fusion of this floor it seems probable that portions of the superincumbent strata, which once formed integral parts of either the coutchiching series or the keewatin, have also been absorbed into the general magma, and reappeared on crystallization as laurentian gneiss. this fusion, however, only extended up to a certain uneven surface, which surface constitutes the demarcation between the present upper and lower archæan. above this surface, or upper limit of fusion, the formation of the coutchiching and keewatin series retained their stratiform or bedded disposition, and rested as a crust of hard and brittle rocks upon the magma, subject to its metamorphosing influences[ ]." [footnote : a large number of classifications have been proposed for the archæan rocks of america; the most plausible one is given in sir a. geikie's _text book of geology_, third edition, p. .] [footnote : lawson, a. c., _report on the geology of the rainy lake region_. montreal, .] [footnote : lawson, _op. cit._ p. .] we may now pass briefly in review the evidence which has been so far obtained as to the mode of formation of the various precambrian rocks. the existence of a very varied fauna amongst the earliest cambrian strata has been commented upon by many geologists, and according to accepted explanations of the origin of that fauna, an enormous period of time elapsed before the deposition of the earliest cambrian strata. during portions of that long period, the undoubtedly clastic rocks of eparchæan type were deposited, and probably many others which are now so altered by metamorphism, like some of the coutchiching rocks of canada, that their original clastic origin can only be inferred and not directly proved. volcanic activity was very rife during the deposition of some of these eparchæan rocks, though perhaps not more so than during the formation of some of the lower palæozoic rocks. all attempts to prove the occurrence of organisms in precambrian strata have hitherto failed, for no undoubted fossil has been described which is unhesitatingly accepted as of precambrian age, notwithstanding the many asserted occurrences of such fossils. that fossils will eventually be discovered is more than probable, and their non-detection at the present time is in no way very surprising, when we remember the long time that elapsed after the existence of stratified rocks below the upper palæozoic rocks had been recognised, before definite faunas were discovered in them. the determination of the precambrian age of stratified rocks is recent, and now that this determination has been made, the search for fossils will be more eager, and is likely to be rewarded by their discovery. furthermore, experience shows that when fossils are discovered in rocks of unknown age, there is a tendency to refer those rocks to some known period, and consequently we may actually possess precambrian fossils, out of beds which have been erroneously referred to the cambrian or a later period. another important question is that of the metamorphism of a large number of precambrian rocks, and here again recent research tends to show that the metamorphism is not of a kind different from that which occurred after the end of precambrian times; the discovery of crystalline schists in norway, kirkcudbrightshire and westmorland amongst lower palæozoic rocks, which resemble those of archæan masses in all respects except in the extent of area which they cover, shows that similar processes to those which occurred in precambrian times went on during later periods, though perhaps not on so large a scale. the great extent of these metamorphic rocks of precambrian age can hardly be due in any great degree to the longer time during which they have been subjected to metamorphic influence, for there is evidence that much of the change took place in precambrian times, far more than has occurred since, and it is a significant fact that these old rocks are more extensively penetrated by intrusive igneous masses than those of later periods; here again we find that much of the intrusion actually occurred in precambrian times. the greater extent of intrusion and metamorphism amongst these precambrian rocks than amongst later sediments indicates some differences of conditions in the case of precambrian and later times. if besides intrusion, actual fusion of floors of precambrian rocks occurred, we may well suppose that the earlier records of the rocks are for ever lost to us, the earliest sediments having been fused, but that the history of life upon our earth is to be revealed to us first in so late a stage as that of cambrian times is highly improbable, and we may look forward with confidence to laying bare the records of the rocks composing the geological column some way below the cambrian portion of the column. upon this foundation of igneous rock, sediment and volcanic material, formed in precambrian times, whose history we have only begun to study, was laid down the great mass of sediment which the geologist has more completely studied, where abundant traces of life are preserved, and concerning whose history we can gain a greater insight than is permitted us in the case of the old foundation stones. chapter xiii. cycles of change in the british area. before studying in further detail the strata of the geological column, it will be convenient to deal with the great physical changes which have occurred in the british area from precambrian times to the present day, as this will clear the way for a right appreciation of the main variations in the characters and distribution of the strata. at the end of precambrian times there was a general upheaval of the british area, and this we may speak of as the first continental period. it was followed by depression and extensive sedimentation, proceeding more or less continuously though with local interruptions through lower palæozoic times, so that so far as britain is concerned we may speak of lower palæozoic times as constituting the first marine period. extensive upheaval gave rise to continental tracts and mountain chains, and deposits of abnormal character (as compared with ordinary marine deposits) at the end of lower palæozoic times;--the devonian period was one of elevation and denudation, and we may therefore refer to it as the second continental period. this was followed by depression and sedimentation in carboniferous times, and these carboniferous times constitute the second marine period. elevation gave rise to continental tracts and mountain chains at the end of carboniferous times, and here again we find proofs of extensive denudation and the formation of abnormal deposits:--the permo-triassic period is the third continental period. depression set in during early jurassic times and continued throughout the mesozoic and the early part of tertiary times, which form the third marine period. disturbances culminating in miocene times once more produced terrestrial conditions. in this, the fourth continental period, we are still living. from what has been previously written it will be seen that each of the marine periods should be marked by an early and late shallow-water phase, separated by an intervening marine phase, and the importance of the phases will depend upon the length of time during which they existed, and will differ markedly in different cases, whilst the distinctness of the middle phase from the upper and lower, will depend upon the magnitude of the maximum submergence. during the first marine period submergence was comparatively rapid, and the shallow-water phase only lasted through very early cambrian times in most regions, whilst the deep-water phase, complicated by many minor upheavals, extended through the main part of cambrian, ordovician and silurian times, and was replaced by the later shallow-water phase at the end of silurian times. the second marine period again was ushered in by rapid submergence, so that the shallow-water phase was brief, and the main mass of the lower carboniferous strata was deposited in deep water; but, unlike the first marine period, the second was characterised by the occurrence of a long interval of time marking the later shallow-water phase, during which the whole of the upper carboniferous strata were deposited. the carboniferous marine period is the simplest of the three with which we have to deal, as the local oscillations occurring on a fairly large scale for such movements were less frequent than was the case during the first and third marine periods. the third marine period had a long shallow-water phase at the commencement, with many minor oscillations, causing great variation in the character of the deposits and frequent minor unconformities. this shallow-water phase existed throughout jurassic and lower cretaceous times. the deep-water phase existed during the deposition of the upper cretaceous deposits, and was succeeded by the second shallow-water phase, when the early tertiary strata were accumulated. the difference between the elevations which accompanied the continental periods and those which have been alluded to as minor elevations is no doubt one of degree, but in considering the british strata only no confusion is likely to arise on this account, as the difference was here very great. the events which occurred during the continental periods are of extreme importance to the geologist. every great upheaval was accompanied by crumpling and stiffening of portions of the earth's crust, and a definite trend was given to the strata as the result of these movements. it is to the earth-movements of the four great continental periods that the present structure of the british isles is largely due, and in any attempt to restore the physical history of our islands considerable attention must be paid to the changes which were produced in the stratified rocks during these periods of earth-movement. chapter xiv. the cambrian system. _classification._ the rocks of the cambrian system when found reposing on precambrian rocks in britain are always separated from the latter by an unconformity. the typical development of the rocks of the system, as the name implies, is in the hilly region of caernarvonshire and merionethshire in north wales, and they are also well represented in south wales, the border counties between england and wales, and the north-west highlands of scotland. two distinct classifications of the cambrian rocks of britain are in use, the original one founded on variations of lithological character, whilst the second depends upon faunistic differences, but the original lithological classification has been to some extent modified to make it locally correspond with the classification based upon palæontological grounds. the following table will shew the differences:-- lithological classification. palæontological classification. tremadoc slate series[ ] beds with intermediate fauna lingula flags series beds with _olenus_ fauna menevian beds (formerly included } in lingula flags) } beds with _paradoxides_ fauna } formerly grouped } solva beds } together as harlech caerfai beds } or llanberis beds beds with _olenellus_ fauna [footnote : in accordance with the custom usually observed in britain, the tremadoc slates are placed in the cambrian system; most continental geologists place them in the succeeding ordovician system. the matter is not an important one, as the fauna is an intermediate one between that of the lingula flags and that of the arenig series of the ordovician system, and the beds are true beds of passage. as the lithological classification is essentially british, it will be as well to retain the tremadoc slates in the cambrian system.] the original lithological classification was essentially the result of prof. sedgwick's work in north wales, while the classification according to faunas is the outcome of the researches of dr hicks in south wales. _description of the strata._ the cambrian rocks of north wales occur in two complex anticlines, separated by an intermediate syncline of ordovician strata occupying the snowdonian hills. the southerly or harlech anticline forms a part of merionethshire to the east of harlech, whilst the northern one is developed around bangor and llanberis. the south welsh cambrian rocks are chiefly found on either side of the pembrokeshire axis of precambrian rocks which runs through st david's. as the corresponding rocks of the two regions were deposited in bathymetrical zones of much the same depth, it will be convenient to give a general account of the rocks of the two regions at the same time, leaving the student to acquire information of the detailed variations in the larger text-books and in special memoirs[ ]. [footnote : a general account of the cambrian, ordovician and silurian rocks will be found in the sedgwick essay for , _a classification of the cambrian and silurian rocks_, though the use of a cumbrous nomenclature therein will tend to confuse the reader. for a detailed account of the cambrian rocks of north wales the reader is referred to the geological survey memoir, _the geology of north wales_, by sir a. ramsay ( nd edition), he may also consult belt, t., "on the lingula flags or festiniog group of the dolgelly district," _geol. mag._, dec i. vol. iv. pp. , , vol. v. p. . the geology of the cambrian rocks is described in a series of memoirs in the _quarterly journal of the geological society_ by dr h. hicks; the following should be consulted: harkness, r. and hicks, h., "on the ancient rocks of the st david's promontory, south wales, and their fossil contents," vol. xxvii. p. ; hicks, h., "on some undescribed fossils from the menevian group," vol. xxviii. p. ; and "on the tremadoc rocks in the neighbourhood of st david's, south wales, and their fossil contents," vol. xxix. p. . see also hicks, "the classification of the eozoic and lower palæozoic rocks of the british isles," _popular science review_, new series, vol. v., and hicks, "life-zones in the lower palæozoic rocks," _geol. mag._ dec iv. vol. i. pp. , and .] the strata of the caerfai and solva groups show the prevalence of the shallow-water phase almost uninterruptedly through the whole of the time occupied by their accumulation in the welsh areas. they consist chiefly of basal conglomerates, succeeded by alternations of grits and shales, though the latter are often converted into slates, owing to the subsequent production of cleavage. the basal conglomerates of the caerfai beds are frequently marked by the existence of enormous pebbles, composed of fragments of the rocks of the underlying precambrian groups, and the possibility of the occurrence of glacial action during their accumulation as advocated by dr hicks must be taken into account. above these beds are various coloured grits, with alternations of muddy sediments often coloured red[ ]. the solva group consists of massive grits, of various colours, also with alternations of mud, which have prevalent purple and green hues. the great thickness of the strata of the caerfai and solva series, which sometimes exceeds , feet, must also be noted. [footnote : in giving this description the red (glyn) slates of north wales are treated as belonging to the caerfai series, though this correlation depends on lithological characters only at present.] the menevian beds consist essentially of very fine, well laminated black and grey muds, which are of a texture favourable for the production of a somewhat regular jointing, causing the rock to break into small rectangular blocks. they are thin, not exceeding feet in thickness, and indicate the incoming of the general deep-water phase of the lower palæozoic epoch. the lingula flags mark a local return to shallower water conditions, especially in the central portion. the total thickness is over , feet, of which the lower stage (locally the maentwrog series) is over feet, and consists of blackish muds, the middle (festiniog stage[ ]) is about , feet thick, and is composed chiefly of shallower water gritty flags, whilst the upper (dolgelly) stage is of about the same thickness as the lower stage and has similar lithological characters. [footnote : the term festiniog has been used for the whole lingula flag series as well as for the middle stage. it will be well to use it with reference to the stage only.] the tremadoc slates are about , feet thick. they are divided into a lower and upper stage, of about equal thickness, and are essentially composed of iron-stained slates, with a considerable admixture of calcareous matter in some parts of south wales, when they furnish the nearest approach to a limestone which has been found amongst the welsh cambrian strata. they were probably formed in a fairly deep sea. much pyroclastic rock and some lava flows are intercalated amongst the welsh cambrian sediments. tuffs are formed in the lower beds of st david's, and lavas and ashes have been found amongst the lingula flags and tremadoc slates of north wales, while the lingula flags of south wales have furnished several bands of ash to the north of haverfordwest. much of the material of the grits and muds may be derived from volcanic rocks, though how far this is so cannot be stated in the absence of information obtained by detailed petrological examination of the rocks. the various isolated outcrops of cambrian strata amongst the counties of the welsh borders and adjoining midland counties indicate a great thinning of the cambrian rocks in this direction. the probable equivalents of the caerfai rocks occur at nuneaton, comley, and on the flanks of the wrekin and malvern hills. the thin basal conglomerates are succeeded by quartzites, and sometimes red calcareous sandstones (comley sandstone). these rocks are succeeded by thin arenaceous and calcareous beds which represent either the solva or menevian beds of wales. the lingula flags are represented by the malvern shales of the malvern area and the stockingford shales of nuneaton, whilst the tremadoc slates have as their equivalents the shineton shales. the exact thicknesses of these deposits do not seem to have been recorded, but prof. lapworth observes that in central shropshire "the comley and shineton groups which ... have a collective thickness of perhaps less than , feet, we have apparently a condensed epitome of the entire cambrian system as at present generally defined." the cambrian rocks of the north-west highlands consist of a thin conglomerate succeeded by grits and flags with shaley beds, and above these a mass of limestone, which may represent some of the ordovician deposits as well as those of cambrian age. pending a complete description of the faunas of these rocks, it is sufficient to state that the only fauna which has hitherto been described in detail indicates the existence of lowest cambrian rocks. further remarks will be made on this head when describing the character of the cambrian faunas. the cambrian rocks of the north-west highlands are also very thin as compared with those of wales, so that the highland and welsh borderland regions appear to have existed as a deeper sea area than that which is indicated by the cambrian rocks of wales, an inference which is to some extent borne out by study of the cambrian rocks of extra-british areas, to which we may now turn. the principal european developments of cambrian rock are found in scandinavia, russia, bohemia and spain, and of these the scandinavian one is by far the most fully developed, as there is a complete sequence in the rocks of that peninsula. they occur both in norway and sweden, but the swedish exposures are the most interesting in most respects, especially those of westrogothia and scania. the rocks are of no great thickness, and consist essentially of black carbonaceous shales, with inconstant bands of impure black limestone composed almost entirely of the remains of trilobites or more rarely of brachiopods. these alum shales, as they are termed, rest unconformably upon precambrian rocks, and have arenaceous and conglomeratic deposits at the base. in russia the rocks are still further attenuated, and have not yielded the relics of so many faunas as have been found in the scandinavian cambrian rocks. the bohemian development is incomplete, owing apparently to an unconformity at the base of the overlying ordovician rocks, while the spanish deposits which seem fairly thick and composed largely of mechanical sediments have not been worked out in very great detail. the american development of cambrian rocks resembles the european one in many striking particulars, and as in the case of europe, there are lateral variations in the lithological characters of the rocks, though in the opposite direction, the shallow-water deposits occurring on the east coast, and the deep-water deposits further west. the general distribution of the different types of cambrian strata in europe and north america has been accounted for on the supposition that in cambrian times a tract of land lay over much of the present site of the north atlantic ocean, and that the detritus of that land formed the shallow-water accumulations of wales and the east of canada, whilst further away from it were deposited the open-sea accumulations of scandinavia and russia on one side and of the more westerly regions of north america on the other, as indicated in fig. . [illustration: fig. . p. precambrian rocks. a. land. x, x´. sea level. bb´. shore deposits. cc´. deep-water deposits. dd´. abyssal deposits. ] _the cambrian faunas._ the cambrian period has been termed the age of trilobites, for they are the dominant forms of the time, but they are associated with many other forms of invertebrata; indeed all the great groups of this division are represented in the earliest cambrian fauna. dr c. d. walcott records representatives of spongiae, hydrozoa, echinodermata, annelida, brachiopoda, lamellibranchiata, gastropoda, pteropoda, crustacea and trilobita as occurring in the _olenellus_ beds of north america and other groups are represented in the rocks of this age in the old world. the cambrian trilobites as a whole are of more generalised types than those of the later systems which furnish their remains, as indicated especially by the looseness of the body, and the large number of body rings in many of the genera, while the tail or pygidium was small and formed of only a few coalesced segments, as pointed out by barrande. in the later trilobites the test is more compact, there are on the whole fewer body rings, as more of these have become fused into a tail which is therefore larger than that of the average tail of the cambrian trilobite. taking the faunas in order, the oldest or _olenellus_ fauna has furnished a great variety of forms in the north-west highlands of scotland, shropshire, scandinavia, esthonia, sardinia, canada, and newfoundland, whilst representative species of the fauna have been recorded also from worcestershire, warwickshire, pembrokeshire, india, china, and australia. the dominant form is the trilobite of the genus or group _olenellus_, which contains a great variety of species referable to three or four divisions which have been ranked as separate genera by some writers. associated with _olenellus_ are trilobites belonging to other genera, which are found in higher deposits, though there represented by different species. brachiopods are fairly abundant, especially those provided with a horny shell; of these, the genus _kutorgina_ is widely distributed. the zoological relationships of several of the fossils of this horizon are as yet doubtful. the archæocyathinæ show affinities with certain corals; a number of tests, included in the genus _hyolithes_ and its allies are doubtfully referred to the pteropods, and the position of the genus _volborthella_ is uncertain. special attention is directed to these doubtful relationships, as it is possible that a number of 'generalised forms' of organisms occur in these strata[ ]. [footnote : for an account of the _olenellus_ fauna see walcott, c. d., "the fauna of the lower cambrian or olenellus zone," _tenth annual report of the director of the united states geological survey_, washington, . it is possible that some of the fossils mentioned in that report belong to strata above that containing _olenellus_.] it should be noticed here that faunas have been discovered which are possibly of earlier date than the _olenellus_ fauna, as they do not correspond with it, or with those of newer strata. one, the _neobolus_ fauna of the salt range of india, occurs in beds below those with _olenellus_, though it is not yet clear that _olenellus_ will not be eventually discovered associated with it, whilst the other, the _protolenus_ fauna of canada, is of unknown age[ ]. [footnote : for an account of the _neobolus_ beds see noetling, f., "on the cambrian formation of the eastern salt range," _records geol. survey, india_, vol. xxvii. p. , and for the protolenus fauna consult a paper by matthew, g. f., "the _protolenus_ fauna," _trans. new york acad. of science_, , vol. xiv. p. .] the _olenellus_ beds are succeeded by beds containing the _paradoxides_ fauna, which have been found in north and south wales, shropshire, scandinavia, bohemia, spain, and north and south america. _olenellus_ and its allies became extinct (or else so scarce that no relics of them have been discovered in the _paradoxides_ beds) before the commencement of the deposition of the strata containing the _paradoxides_ fauna, and few genera pass from the beds with the one fauna to that containing the other. the _paradoxides_ fauna existed for a considerable period, and the beds have been divided into a series of zones characterised by different species of _paradoxides_, thus dr hicks records the following zones in pembrokeshire[ ]:-- zone of _paradoxides_ _davidis_ } menevian. " " _hicksii_ } " " _aurora_ } " " _solvensis_ } solva. " " _harknessi_ } [footnote : the order here as elsewhere is _ascending_, i.e. the newest deposit is placed at the top.] dr tullberg divides the _paradoxides_ beds of scania into thirteen zones, though only a few of these are characterised by definite species of _paradoxides_. the _olenellus_ beds have not yet been divided into zones, though this will probably be the outcome of further study[ ]. [footnote : the _paradoxides_ fauna is described in the following works: britain, hicks, h. and salter j. w., _quart. journ. geol. soc._, vol. xxiv. p. , xxv. p. , xxvii. p. , and hicks, h. and harkness, r., _ibid._ vol. xxvii. p. ; scandinavia, angelin, n. p., _palæontologia scandinavica_; brögger, w. c., _nyt magazin for naturvidenskaberne_, vol. xxiv., linnarsson, g., _sveriges geologiska undersökning_, ser. c. no. ; bohemia, barrande, j., _système silurien du centre de la bohême_; spain, prado, c. de, "sur l'existence de la faune primordiale dans la chaîne cantabrique suivie de la description des fossiles par mm. de verneuil et barrande," _bull. soc. geol. france_, series, vol. xvii. p. ; america, walcott, c. d., _bull. u. s. geol. survey_: "the cambrian faunas of north america," and matthew, g. f., _trans. roy. soc. canada_, and succeeding years.] the strata with _paradoxides_ are succeeded by those with the _olenus_ fauna, characterised by the genus _olenus_ and a large number of allied genera or sub-genera as some prefer to term them. the genus _olenus_ (_sensu stricto_) is very abundant in the lower part of the series, whilst the allied forms are more abundant in the upper beds. the genus _paradoxides_ and its associates disappeared before the deposition of these strata containing _olenus_ and its allies, and indeed the complete change in the character of the faunas in europe is very remarkable. the _olenus_ fauna has been found in north wales, pembrokeshire, warwickshire, worcestershire, and abroad in scandinavia and canada. it is interesting to note among the fossils of the _olenus_ beds the occurrence of a graptolite which is associated with _olenus_ in scandinavia; this is the earliest recorded appearance of a group which is destined to play so important a role amongst the fossils of the succeeding system[ ]. the following zones have been detected by dr s. a. tullberg amongst the _olenus_ beds of scania:-- zone of _acerocare ecorne_. " _dictyograptus flabelliformis_. " _cyclognathus micropygus_. " _peltura scarabæoides_. " _eurycare camuricorne_. " _parabolina spinulosa_. " _ceratopyge_ sp. " _olenus_ (proper). " _leperditia_. " _agnostus pisiformis_. [footnote : for descriptions of the _olenus_ fauna consult the following:--wales, belt, t., _geol. mag._ dec. i. vol. v. p. , and salter, j. w., _decades geol. survey_, decade ii. pl. ix. and decade xi. pl. viii.; scandinavia, angelin, n. p., _palæontologia scandinavica_, and brögger, w. c., _die silurischen etagen und im kristianiagebiet und auf eker_; canada, matthew, g. f., "illustrations of the fauna of the st john group, no. vi.," _trans. roy. soc. canada_, .] the beds with _dictyograptus flabelliformis_ form a wonderfully constant horizon at or near the top of the _olenus_ beds. they are found in north wales, the border counties between wales and england, france, scandinavia, russia and canada. the passage fauna of the beds which are the equivalents of the tremadoc slates may be spoken of as the _ceratopyge_ fauna, for _ceratopyge forficula_, a remarkable species of trilobite, characterises it in scandinavia, and will probably be found elsewhere. _ceratopyge_ beds have been found in north and south wales, shropshire, scandinavia, bavaria and north america, and in each case the fauna is intermediate in character between that of the cambrian and that of the ordovician system, containing the loosely-formed trilobites of the former with the more compact ones of the latter. the genus _bryograptus_, a many-branched graptolite, also appears to characterise this fauna[ ]. [footnote : for accounts of the tremadoc slates fauna in england and wales see ramsay, a. c., _geology of north wales_, appendix; hicks, h., _quart. journ. geol. soc._, vol. xxix. p. ; callaway, c., _ibid._ vol. xxxiii. p. , whilst many of the foreign fossils are noticed in brögger's _die silurischen etagen und _ and barrande's _faune silurienne des environs de hof en bavière_.] the faunas of the cambrian rocks have not been studied in sufficient detail, with reference to the physical surroundings of the organisms, to throw much light upon the conditions under which the strata were deposited, though the evidence obtained from an examination of the lithological characters of the deposits is generally corroborated by study of the organic contents. chapter xv. the ordovician system. _classification._ the ordovician strata were originally divided into series by sedgwick as follows:-- upper bala, middle bala, lower bala, arenig. the arenig series was at one time included by some writers with the lower bala under the name llandeilo, but the word llandeilo is now used in the sense of sedgwick's lower bala. the middle bala is often spoken of as caradoc, but the terms bala and caradoc are sometimes used interchangeably. as much confusion attaches to the use of the name bala without explanation, the alternative titles have been largely adopted, and as the series are well defined there is no objection to their use, save that some expression is wanted equivalent to upper bala. the local term ashgill shales was originally applied by mr w. talbot aveline to beds of this age in lakeland, and i have elsewhere suggested the use of this name for the whole series in that region; its use may well be extended to the series which is developed in many parts of britain and the continent. the terms which will be used here, therefore, for the different series of the ordovician system are the following:-- ashgill series (= upper bala) caradoc " (= middle " ) llandeilo " (= lower " ) arenig " adopting a palæontological classification, we may speak of the arenig and llandeilo beds as those containing the _asaphus_ fauna, whilst the caradoc and ashgill beds possess the _trinucleus_ fauna; this is the terminology employed by angelin for the equivalent strata of sweden. it must be noted that here the names applied are not those of absolutely characteristic genera, as was the case with those adopted for naming the cambrian faunas, for both _asaphus_ and _trinucleus_ range through the beds of the system; but whereas _asaphus_ is most abundant in the beds of the two lower series, _trinucleus_ occurs most frequently in those of the two upper series. _description of the strata._ the ordovician rocks are found over large tracts in north and south wales, in the counties on the welsh border, in lakeland and the outlying districts in the southern uplands of scotland, and in detached areas in ireland. there are three main types of deposit:--(i) the volcanic type, in which the ordinary sediments are associated with a large amount of contemporaneous volcanic matter, (ii) the black shale type, with a fauna consisting largely of graptolites, and (iii) the ordinary sedimentary type, in which we find alternations of grits, shales, and more or less impure limestones. we also find developments which are intermediate between any two or even all three of these types. the first type is characteristically developed in caernarvonshire and merionethshire, the second in the dumfriesshire uplands, and the third in the girvan district of ayrshire. the variation in the thickness of these three types of deposit is shown in the accompanying sections of the caernarvon, merioneth, moffat and girvan regions (see fig. ). [illustration: fig. . showing the variations in the characters of the ordovician deposits of the three principal types. scale in. = feet. a = arenig. l = llandeilo. c = caradoc. the thickness of the arenig rocks of the scotch areas is unknown.] the north welsh area gives two different developments of the ordovician strata, one of which is much less volcanic than the other. in the merioneth-caernarvon area, two great masses of volcanic rock form the aran and arenig hills of merioneth and the snowdonian group of caernarvon. the former are of arenig, the latter of caradoc age. the merionethshire volcanic rocks consist of a great thickness of lavas and ashes of intermediate composition (anderites), associated with sandy and muddy sediments of no great vertical depth. the llandeilo beds of this area are chiefly of the nature of black shales, while the caradoc series is represented by volcanic lavas and ashes of acid composition (felsites) with a few thin interbedded sediments. a calcareous ash forming the summit of snowdon is of importance as being on the same horizon as a limestone (the bala limestone) found in the other north welsh area. the ashgill series is not represented in snowdonia. in the other north welsh tract, around bala lake, the volcanic matter is much less conspicuous. the arenig rocks are not seen nearer than the arenig mountains which form the western boundary of this second tract. the llandeilo beds consist of shaley deposits with a well-marked limestone, the llandeilo limestone, in the centre, whilst the caradoc beds consist chiefly of muddy sediments with some thin ashes and a limestone, the bala limestone, at the top. the ashgill series contains a basal limestone, the rhiwlas limestone, succeeded by shales, and another thin limestone called the hirnant limestone at the summit. in south wales the arenig beds[ ] are chiefly composed of slates, and are divisible into an upper and lower group. the total thickness is about feet. the llandeilo beds contain three series:-- upper llandeilo slates llandeilo limestone lower llandeilo slates . [footnote : a remarkable fauna, fairly well represented in britain and exceedingly well developed on the continent, exists in the uppermost arenig and lower llandeilo beds, and it is well separated from the dominant arenig fauna below and llandeilo fauna above. to the beds which contain it dr hicks has given the name llanvirn series.] the caradoc beds consist of black graptolitic shales of no great thickness, succeeded by an impure limestone on the horizon of the bala limestone, while the ashgill series like that of north wales is separated into upper and lower limestone stages with an intervening stage composed of shales. the deposits of the welsh borderland are well developed in shropshire, where there is practically a repetition of the caernarvon-merioneth development, with variations in detail. the arenig and caradoc volcanic rocks are not so thick as those of the welsh district, but are nevertheless of considerable importance[ ]. [footnote : for information concerning these beds see lapworth, c. and watts, w. w., "the geology of south shropshire," _proc. geol. assoc._, vol. xiii. p. .] in the hilly region of cumberland, westmorland, and the adjoining parts of yorkshire the succession differs from that of any of the welsh regions, for the great period of volcanicity was during the formation of the llandeilo rocks, and there were merely sporadic outbursts in arenig and caradoc times. the arenig rocks consist of black shales with interstratified beds of coarser sediment, and some thin lavas and ashes of intermediate type. the llandeilo series is represented by a very great thickness of volcanic rocks, varying in composition from basic to acid lavas, with associated pyroclastic rocks. the rocks of the caradoc period largely consist of impure limestone with associated argillaceous rocks, and contemporaneous volcanic rocks of acid character. a marked unconformity is found locally in the centre of these. the ashgill series consists of a basal limestone with shales above, and there is evidence that volcanic activity had not become extinct during the deposition of the rocks of this series. passing on to scotland, the graptolitic type is admirably shown in the southern uplands of the neighbourhood of moffat, dumfriesshire. the base of the ordovician system has not been found, but the lowest series seems to be represented by shales with a graptolite possibly of arenig age. above this are volcanic beds succeeded by a group of black shales known as the moffat shales. they are only about six hundred feet in thickness, and yet represent much of the ordovician and part of the silurian strata as developed elsewhere. the beds belonging to the ordovician system are divided into two series, the glenkiln shales below and the hartfell shales above. the former consist of intensely black muds with few fossils save graptolites, and a deposit of chert at the base which is composed of radiolaria. the graptolites of the black shales are upper llandeilo forms, but the thin deposit of radiolarian chert may represent the rest of the llandeilo period and part of the arenig period also. the hartfell shales are also usually black graptolite shales with lighter deposits nearly barren of organic remains; they represent the caradoc and ashgill series and pass conformably into the deposits of silurian age[ ]. the ordinary sedimentary type of ordovician rocks is found in ayrshire, though a few thin graptolitic seams are intercalated with the conglomerates and shelly sands, clays and limestones of the region, which is therefore peculiarly valuable as affording a means of comparison of the shelly type with the graptolitic type of ordovician deposits. the arenig series consists of black shales with graptolites, and these rocks are succeeded by a volcanic group which is probably of llandeilo age. above these volcanic beds, as in dumfriesshire, we find three great divisions, two of which are of ordovician, the third of silurian age. the ordovician divisions are respectively termed the barr series, which is the equivalent of the glenkiln shales, and the ardmillan series above, equivalent to the hartfell shales[ ]. [footnote : the moffat beds are described in a paper by prof. lapworth entitled "the moffat series" in the _quarterly journal of the geological society_, vol. xxxiv. p. . this paper, which is a masterpiece of detailed work, has furnished a clue to many problems. few students will be able to follow the numerous details, and for general information concerning the beds they are recommended to read another paper by the same author "on the ballantrae rocks of south scotland," _geol. mag._ dec. iii. vol. vi. p. . an account of the radiolarian cherts by dr g. j. hinde will be found in the _annals and magazine of natural history_ for july, , p. .] [footnote : see lapworth, c., "the girvan succession," _quart. journ. geol. soc._, vol. xxxviii. p. , and also the paper on the ballantrae rocks referred to in the preceding footnote. the latter paper should be carefully read by all students of the stratigraphy of the lower palæozoic rocks.] it is interesting to find that in the north of ireland the rocks generally coincide in characters with those which are found along the same line of strike in great britain; thus, the girvan type appears in londonderry, tyrone and fermanagh, the moffat type in county down, and the lake district type in the counties of dublin and kildare. on the continent the volcanic material which plays so important a part in the constitution of the ordovician accumulations of britain is practically absent, and the strata are largely composed of accumulations of shale and limestone with occasional coarser deposits. in scandinavia, the arenig beds consist of limestones with a few shales, the llandeilo deposits are largely calcareous, those of caradoc age are partly calcareous and towards the top usually argillaceous, while the equivalents of the british ashgill series are calcareous at the base and argillaceous at the summit. in russia the calcareous matter preponderates over the argillaceous material. ordovician strata are also found in belgium, france, bohemia, and other places, and are largely composed of mechanical sediments of varying degrees of fineness mixed occasionally with some calcareous matter. the variation in the characters of the ordovician strata of britain points to accumulation in a fairly deep sea, usually at some distance from the land, but dotted over with volcanoes which often rose above the water, causing the addition of much volcanic material to the ordinary sediments, and the existence of minor unconformities at different horizons along their flanks. as these unconformities are not always associated with volcanic material it is obvious that uplifts must have occurred occasionally during the deposition of the rocks; one important uplift is indicated by the occurrence of an unconformity in the arenig rocks of wales, while another is seen amongst the caradoc rocks of the welsh borders. on the whole, however, the period was one of slow subsidence, the deposition of material generally keeping pace with this subsidence, and accordingly there is a great uniformity of characters amongst the strata over wide areas. the probable continuation through the ordovician period of the tract of land over the present site of the n. atlantic ocean which as we have reason to suppose existed during cambrian times, is indicated by similar changes of lithological character amongst the strata when traced from britain eastward to russia in both cambrian and ordovician times, and the continuance of these conditions over the american area is also indicated by study of the variations amongst the american ordovician deposits. _the ordovician faunas._ the ordovician period has justly been termed the period of graptolites, which are the dominant forms of the time, and continue in abundance throughout the period. the abundance of graptolites in black shales associated with few other organisms has often been noted. it appears to be due to a large extent to the slow accumulation of the graptolitic deposits, allowing an abundance of these creatures to be showered upon the ocean floor, after death, for the evidence derived from detailed examination of their structure points to their existence as floating organisms. the tests of other creatures largely calcareous may well have been dissolved before reaching the sea-floor. in support of the view that these black shales are abysmal deposits may be noted the singular persistence of their lithological characters over wide areas, their replacement by much greater thicknesses of normal sediments along the ancient coast-lines, the frequent occurrence together of blind trilobites with those having abnormally large eyes when these creatures are associated with graptolites in the black shales, and lastly the interstratification of the black shales with radiolarian cherts similar to the modern abysmal radiolarian oozes. if this be so, we ought to find graptolites in marine deposits of all kinds, and indeed they are found there, though largely masked by the mass of sediment and the hosts of other included fossils, so that their discovery is rendered much more difficult than when they occur in the black shales,--a state of things which is familiar in the case of other pelagic organisms as _globigerinæ_, radiolaria, and pteropods, whose tests abound in the abysmal deposits and are comparatively rare in those of terrigenous origin[ ]. [footnote : the importance of the graptolites as indices of the geological age will be seen by perusal of prof. lapworth's paper "on the geological distribution of the rhabdophora," _ann. and mag. nat. hist._, ser. , vol. iii. ( ).] the characters of the ordovician trilobites have already been noticed. these organisms are abundant, and occur in sediments of all kinds. of other groups, the significance of the radiolaria has been referred to above. corals occasionally form reef-like masses of limestone as in the limestones of the caradoc epoch; the echinoderms are well represented, cystids being locally abundant; of the crustacea, many remains of tests of phyllocarida have been recorded; the brachiopods are very abundant, and of the mollusca, lamellibranchs, gastropods and cephalopods all occur with frequency though none of these groups is very prevalent. certain forms have been referred to pteropods though with doubt, and other shells seem to be referable to the heteropods. the existence of vertebrates during ordovician times is not, in the opinion of many geologists, proved, though remains of fishes have been recorded from the ordovician strata of north america; but it is desirable that more evidence of this occurrence should be given[ ]. [footnote : walcott, c. d., "preliminary notes on the discovery of a vertebrate fauna in silurian (ordovician) strata," _bulletin geol. soc. america_, vol. iii. p. .] the distribution of the ordovician faunas like that of the sediments points to the prevalence of open ocean conditions over wide areas during the period, with occasional approaches to land, which was often of a volcanic nature. around this land clustered the ordinary invertebrates, building up coral-reefs and shell-banks, whilst away in the open oceans the graptolites floated, almost alone, and sank to the ocean floor after death. chapter xvi. the silurian system and the changes which occurred in britain at the close of silurian times. _classification._ the silurian system was originally divided by its founder, sir r. i. murchison, into three series, as follows:-- ludlow series wenlock " llandovery " the term may hill, proposed by sedgwick, is sometimes used as synonymous with llandovery. this classification omits a somewhat important set of beds intercalated between those of the llandovery and wenlock series known as the tarannon shales, and in britain if we were to classify afresh, it would be more convenient to include some of the beds formerly referred to the ludlow in the wenlock. i shall, however, adopt the old and well-established classification, adding the term tarannon to llandovery, and speaking of the llandovery-tarannon series. the nature of the two classifications is shown in the following table: old new palæontological stages. classification. classification. classification. upper ludlow } } } aymestry limestone } ludlow } downtonian } lower ludlow } } fauna } } with wenlock limestone } } } _encrinurus_ wenlock shale } wenlock } salopian } woolhope limestone } } } tarannon shales } } fauna upper llandovery } llandovery } valentian } with lower llandovery } } } _harpes_ [illustration: fig. . l = ludlow. w = wenlock. ll-t = llandovery-tarannon.] _description of the strata._ lithologically the silurian deposits of britain form a continuation of those of the ordovician period, with a local interruption due to the elevation of portions of wales and the welsh borders at the close of ordovician times. elsewhere we find a predominance of shales passing into grits at the top of the system, the change indicating the incoming of the shallow-water phase before the commencement of the second continental period. particular stress is laid upon the predominant shaley character of the beds, for, on account of the richness and variety of the faunas of the calcareous rocks, greater attention is naturally paid to them in geological works, and the student may get a false idea of their relative importance. an attempt is made below (fig. ) to give a general idea of the variations in lithological characters of the silurian rocks in different parts of britain. the silurian strata are mostly found in the same localities as those which furnish exposures of the rocks of ordovician age. the development in the typical silurian region of the welsh borders is characterised by the abundance of calcareous matter which is found there as compared with that which exists in the other british localities. the llandovery strata are sandy, often conglomeratic, with a fair amount of calcareous matter in places. the arenaceous nature is undoubtedly due to the proximity of land caused by local upheaval at the end of ordovician times, and the upper llandovery rocks sometimes rest unconformably on the lower ones, at other times on ordovician, cambrian, or even precambrian rocks. the tarannon shales are light green shales with intercalated grits. the wenlock series consists of a group of shales separating a lower, very inconstant, earthy limestone from an upper, more constant, thicker and purer limestone. the latter, the wenlock limestone, is composed of fragments and perfect specimens of various fossils, and the fragmentary nature of many of the shells indicates the occurrence of wave-action and probable formation in shallow water, in some places against coral-reefs. the lower ludlow beds consist of sandy shales; they are separated from the upper ludlow beds by an impure limestone, the aymestry limestone. the upper ludlow beds consist mainly of grits and flags, often coloured red towards the summit. in north wales the llandovery beds occasionally present the shelly arenaceous types of deposit as near llangollen, at other times as near conway, corwen, and in anglesey, the graptolitic shale type. they also rest unconformably upon the ordovician rocks in this area. the tarannon shales resemble those of the border county. the wenlock series consists essentially of shales, while the ludlow development differs from that of the borders in its greater thickness and the absence of any calcareous band in the centre. in central wales the graptolitic type of the llandovery-tarannon series is found, but the graptolite-bearing shales of the llandovery epoch are thin beds occurring between grits and flags no doubt deposited in shallow water, and this division of the series is of very great thickness. in south wales the silurian rocks are very similar to those of the welsh borders, save that the calcareous deposits are fewer and thinner. the lake district silurian strata generally resemble those of north wales. the llandovery-tarannon rocks are of the graptolite-shale type, intercalated with fine grits in the case of the beds of tarannon age. the wenlock beds consist of shales, and the ludlow beds of gritty shales beneath, and massive flags and grits at the summit. these ludlow beds are here of great thickness (certainly not less than feet) and were obviously accumulated for the most part in shallow water. the llandovery-tarannon rocks of southern scotland show the two types which prevailed in the moffat and girvan areas in later ordovician times. the llandovery beds of moffat are known as the birkhill shales, and are very thin. the representatives of the tarannon shales, however, the gala beds, consist mainly of grits, and attain a great thickness. in the girvan area, the llandovery beds are of the shelly type. here as at moffat and in the lake district there is perfect conformity between the beds of ordovician and those of silurian age, and accordingly it is instructive to note the completeness of the palæontological break, especially in the moffat district. the higher silurian beds of southern scotland present a general resemblance to those of north wales and the lake district[ ]. [footnote : for descriptions of the silurian beds of the typical region see lapworth and watts, _proc. geol. assoc._, vol. xiii. p. , those of wales are described by lake and groom, _quart. journ. geol. soc._, vol. xlix. p. , and lake, _ibid._ vol. li. p. . a description of those of lakeland will be found in the memoir of the geological survey "the geology of the country around kendal, etc." while the scotch rocks are described in lapworth's papers on moffat and girvan.] on the european continent we find indications of conditions similar to those which prevailed during the ordovician period; the strata become much thinner and more calcareous in scandinavia, and still thinner in the baltic provinces of russia, where they consist very largely of calcareous matter. in central europe the greater abundance of calcareous matter, compared with that which is found in the ordovician strata of that region, points to a change in physical conditions which became still more marked after silurian times. in north america, the succession is very similar to that of britain, the calcareous development of the silurian rocks being found around niagara, but towards the close of silurian times the shallow-water phase became marked in places by the deposition of chemical precipitates which indicate the separation of a portion of the late silurian ocean from the main mass during the period of formation of these abnormal deposits. the conditions of silurian times, until the advent of the shallow-water phase, recall those of ordovician times and point to a wide expanse of ocean at some distance from the land, though the earliest deposits become arenaceous where they were deposited against an old land surface formed by the elevation of the welsh ordovician rocks, which were denuded to supply this material. one marked difference existed between the physical conditions of our area during ordovician and silurian times, for the volcanic activity which was rife during ordovician times almost ceased during silurian times, except in the region now occupied by the extreme south-west of ireland, and accordingly volcanic material does not appreciably contribute to the formation of the silurian deposits. the shallowness of the sea-floor at times is marked by the occurrence of masses of reef-building corals in the limestones, and these probably indicate the prevalence of a fairly warm climate, an inference supported by the nature of the gastropod fauna of gothland, as noticed in chap. ix. the shallow-water phase commences fairly simultaneously over the whole area at the beginning of the deposition of the lower ludlow rocks, and becomes more marked in the upper ludlow rocks, being most noticeable at their extreme summit, when a change occurred which will be considered at the conclusion of this chapter. _the silurian faunas[ ]._ the silurian period has been termed the period of crinoids, and this group of creatures certainly contained a great variety of very remarkable forms, which are specially numerous in the wenlock limestone of the welsh borders, gothland, and north america, but many of the rocks of the system display few traces of these organisms. the trilobites and graptolites still contribute largely to the fauna, the latter becoming very scarce at the summit of the system, though a few specimens have been detected in the rocks of the succeeding system. the trilobites belong to few genera though these are mostly more highly organised than those of the ordovician period. the genus _harpes_ has been taken as fairly characteristic of the lower part of the system in sweden, and it occurs there abundantly in places in britain, whilst _encrinurus_ is more abundant in the upper series, but both of these genera range from higher ordovician beds into the devonian. mention has already been made of the corals. brachiopods are very abundant, and mollusca appear with considerable frequency. the appearance of true insects is of importance, cockroaches have been recorded from silurian rocks and a number of other insects have lately been recorded from canada[ ]. eurypterids occur in considerable abundance in the higher parts of the system, as do also the remains of fish. [footnote : for an account of the silurian faunas the student may consult sir r. i. murchison's _silurian system_ or the shorter _siluria_ and lapworth's paper on the geological distribution of the rhabdophora.] [footnote : see an article by dr g. f. matthew, "description of an extinct palæozoic insect and a review of the fauna with which it occurs," _bulletin_ xv. _of the natural history society of new brunswick_. the silurian rocks of the little river group of st john, new brunswick, have yielded species of land snails, two doubtful saw-bugs, several arachnids, and myriopods, two insects of the order thysanura (spring-tails), and eight palæodictyoptera.] the close of silurian times ushered in the second continental period in britain when a large part of our area and the adjoining areas to the north and north-east were uplifted to form land, which in the case of our area was interpenetrated by watery tracts, whose exact nature is still a subject of dispute. accordingly the deposits which were formed during this period are local and in some cases abnormal, but they will be considered in the next chapter. simultaneously with the formation of these deposits, uplift of the sea-floor converted wider and wider areas into land, and this land underwent considerable denudation, so that the tops of the anticlines were worn away. the general trend of the anticlines was east-north-east and west-south-west, and accordingly a series of mountain chains possessed that direction, for the epeirogenic movements were accompanied by orogenic ones. between the regions of uplifts were depressions in which sediments accumulated. the principal axes of uplift in our area range through the north of scotland towards scandinavia, across the southern scotch uplands to the north of ireland, through the lake district and through wales. as the result of lateral pressure, a cleavage structure was impressed on many of the lower palæozoic rocks, the strike of the rocks extended in the direction of the ridges and depressions, and the rocks as a whole became considerably compacted and hardened, thus producing one of the most important portions of the framework of our island, for although the ancient mountain chains were largely denuded during their elevation, and their stumps were afterwards covered by later deposits, upon the removal of these, the ancient stumps were once more exposed as fairly rigid masses which do not yield greatly to denuding influences, and accordingly stand out as the most important upland regions of britain at the present day. it is interesting to notice, as an illustration of the now well established fact that successive earth movements often occur in the same direction, that the axes of the folds produced during this second continental (devonian) period, run parallel with the lines separating tracts of different lithological characters. it has been seen that the ordovician and silurian rocks of the southern uplands continue into ireland, and that the beds of similar characters run in belts having a general east-north-east and west-south-west trend, which accordingly must have been the direction of the coast-line parallel to which they were deposited, and as that coast-line was due to uplift, the movement which produced it would naturally produce foldings with east-north-east and west-south-west trend. this is one of many cases where the lines separating belts of rock having different lithological characters run parallel to axial lines of folds which have been produced in the rocks at a later period. as the result of the existence of land over parts of north-west europe in devonian times, it is comparatively rare to find a passage from normal silurian rocks into normal devonian ones; there is often an unconformity above the silurian strata. as we proceed southwards towards central europe, where the epeirogenic and orogenic movements died out, this is not the case, and we get complete conformity between marine sediments of the silurian and devonian periods. chapter xvii. the devonian system. _classification._ as a result of the movements which were briefly described in the last chapter, two types of devonian deposit are found in the british isles, and are called respectively the devon type and the old red sandstone type. the latter rocks, formerly divided into three divisions, are now separated into two only, the upper and lower old red sandstone, and the exact relation of these to the different subdivisions of the rocks of devon type remains to be settled. the devon type itself has given rise to much difference of opinion, two local classifications have been applied, one for the rocks of north devon and another for those of south devon. the classification which has been most generally adopted is as follows:-- n. devon. s. devon[ ]. { pilton beds { entomis slates upper devonian { cucullæa (marwood) { goniatite limestones (clymenian) { beds { and slates { pickwell down sandstone { massive limestones middle devonian { morte slates { middle devonian (eifelian) { ilfracombe beds { limestones { ashprington volcanic { series { eifelian slates and { shaly limestones { lower devonian lower devonian { hangman grits { slates (coblenzian) { lynton slates { lincombe and warberry { foreland grits { grits and { meadfoot sands [footnote : an account of the south devon rocks by mr ussher will be found in the _quart. journ. geol. soc._, vol. xlvi. p. ; from it the above classification of the rocks of s. devon is taken.] the division into lower middle and upper devonian is generally adopted, though the alternative titles given to these divisions are not always used with the same signification, and the distribution of the different local stages given in the above classifications is usually adopted in the main, though a detailed comparison of the devonian beds of north and south devon is still attended with difficulty. more than once an attempt has been made to prove that the apparent succession of the north devon rocks, which is that given in the above table, is not the true one, and of recent years dr hicks has obtained a number of fossils from the morte slates which had hitherto yielded none, and he believes that these fossils indicate that the morte slates are on a lower horizon than the beds on which they rest. whatever be the ultimate verdict, we can, at any rate, say that the "devonian question," as it is termed, is not settled[ ]. [footnote : see hicks, h., "on the morte slates and associated beds in north devon and west somerset," _quart. journ. geol. soc._, vols. lii. p. , liii. p. .] _description of the strata._ the general variations in the lithological characters of the deposits of devonian age will be seen from the accompanying figure which represents the deposits of britain as they occurred from north to south before they had been affected by subsequent earth-movements (fig. ). the conventional signs which are used are similar to those which have been used in other parts of this work, and will save description of the section. [illustration: fig. . a. lower palæozoic and precambrian rocks. n.s. north of scotland } c.v. central valley of ditto } old red sandstone type. w. wales } n.d. north devon } devon type. s.d. south devon } ] the ridges separate different deposits of devonian rocks, which were possibly deposited in isolated areas, though there was probably connexion between them at any rate at times. the old red sandstone type consists to a large extent, as the name implies, of sandstones which are coloured red by a deposit of peroxide of iron around the sand grains. they are separable into a lower and upper division with an unconformity often occurring between them. the lower old red passes down in places into the silurian rocks with perfect conformity, and the upper old red similarly passes up into the carboniferous strata. the existence of pebble beds at different horizons is a noteworthy feature. they are frequently found at or near the base of the two divisions. the sandstones of the lower division are often accompanied by flagstones, while the red sandstones of the upper division usually have deposits of yellow and brown sandstone intercalated between them. inconstant beds of limestone, known as cornstones, are found in both divisions, and prof. sollas has shown that some of these, at any rate, are true mechanical deposits, formed by the destruction of pre-existing strata of limestone and the deposition of the resulting fragments from a state of suspension. in scotland a great thickness of volcanic material of various kinds is associated with the two divisions. for the sake of simplicity this is omitted from fig. [ ]. it is not known how far normal sediments are associated with the old red sandstone type of deposit. the existence of some in south wales is suggested by evidence supplied by the late mr j. w. salter. [footnote : for an account of these and all other british volcanic rocks the reader is referred to sir a. geikie's work on _the ancient volcanoes of great britain_. macmillan and co., .] the devon type, as will be seen in the figure, consists of rocks which are to a great extent of normal character. we find in devonshire alternations of sandstones, shales and limestones, but even here, red sandstones, which are comparable with those of the old red type occur in diminished amount: the foreland grits and pickwell down sandstones are both coloured red, and are like the sandstones formed further north. the recognition of this fact induces one to believe that the contrast between the two types of rock which are found at a short distance from one another on opposite sides of the bristol channel is not so marked as one is sometimes led to suppose. the rocks of north devon differ from those of south devon chiefly owing to the amount of calcareous sediment found in the two areas, for limestones occur in south devon to a great extent, and in north devon there is a comparative poverty of this kind of sediment. here, again, the apparent difference is possibly greater than the real one. the north devon limestones have in places been stretched out after their formation and thus rendered thinner, and the highly-cleaved limestones are occasionally mistaken for shales, while in south devon there is evidence of thickening of the limestones by folding subsequently to their deposition. allowing for these changes, however, there is still a marked diminution in the amount of coarse mechanical sediments and increase in the quantity of calcareous matter as one passes from north to south devon, and this prepares one for the condition of things met with on parts of the continent, where the mechanical sediments become finer and thinner on the whole as one travels southward, until, when we reach the bohemian area, the devonian rocks are found to be largely composed of calcareous sediments. it is interesting to find that in north america the two types of devonian strata recur, and present characters generally similar to those which they possess upon this side of the atlantic. passing now to a consideration of the conditions under which the devonian rocks were deposited, we may examine the bearing of the character of the strata as a whole, and then proceed to more detailed consideration of the nature and conditions of deposits of the two types. the gradual increase in calcareous matter and dying out of mechanical sediments as one travels southward points to recession from land in that direction, and we have already seen that the epeirogenic and orogenic movements of this continental period elevated the silurian sea-floor in the north, and gave rise to a northern continent, while oceanic conditions continued further south, and allowed the accumulation of sediments lying conformably upon those of silurian age, and giving indications of the prevalence of physical conditions during devonian times which were in the main similar to those of the preceding silurian period. in the shallow waters adjoining the land of the northern continent the old red sandstones were laid down, and the exact conditions under which they were accumulated is a matter of some interest. the late sir andrew ramsay gave reasons for supposing that many red deposits were accumulated in the waters of inland lakes, which underwent rapid evaporation, and his views have been applied, with much corroborative evidence by sir a. geikie, to account for the red sandstones of devonian age, which he believes to have been accumulated in a series of inland lakes, though others hold a different opinion, and consider that the old red sandstone waters had a direct connexion with those of the open ocean; the question is too intricate to be discussed at length here. besides the difference of physical characters of the two types of strata, the difference in the nature of their included organisms is significant. the ordinary invertebrates, as corals, crinoids, brachiopods and molluscs are extremely rare in the old red sandstone, which contains remarkable remains of agnatha fishes and eurypterids, and although these are also found associated with a true marine fauna in russia, germany and bohemia, the rarity or apparent absence of the ordinary marine invertebrates, though only negative evidence, which is proverbially dangerous, must be regarded. the north devon rocks are sediments which might well be accumulated on the shores of a continent, while those of south devon, with their abundant coral reefs, and other organic limestones were no doubt deposited in a clearer sea, at a greater distance from the land, and the clear water deposits of germany and still more of bohemia, were accumulated in the open ocean. it is interesting to note in these bohemian deposits abundance of shells of a pteropod _styliola_ which has been proved by prof. h. a. nicholson to form masses of limestone in the devonian system of canada. the modern distribution of the pteropoda suggests the open ocean character of the deposits which contain them even so far back as devonian times, though one cannot conclude that these deposits are really analogous to the so-called pteropod ooze of modern seas which, as a matter of fact, is largely composed of foraminiferal tests with a considerable percentage of pteropod shells. _the devonian flora and faunas._ the plant remains in the lower palæozoic rocks are few in number. some undoubted terrestrial plants have been discovered, but the prevalent flora of lower palæozoic times, so far as yet known, was one consisting of algæ. in devonian times we begin to meet with a number of cryptogams of higher type, allied to those which form the dominant flora of the succeeding period. the fauna is in many ways remarkable. the devonian period has been termed the period of ganoid fishes, and the remarkable remains, so graphically described by the late hugh miller, are indeed peculiarly characteristic of devonian times, but they are largely though by no means exclusively entombed in rocks of the old red sandstone type[ ]. the devon type of rock contains a great abundance and variety of the problematical group, the stromatoporoids, which contribute extensively to the formation of many of the limestones, and although these organisms are not by any means confined to devonian strata, their abundance and variety therein might lead one to speak of the period as that of stromatoporoids. the remains of corals are very abundant in the limestones, and, as already stated, frequently give rise to true reef-masses. the graptolites, as remarked in the previous chapter, disappear in the rocks of the devonian period, and as only one or two fragments have been found, we may assert that the group was practically extinct at the end of silurian times, though species of one genus, _monograptus_, lingered for a short time in greatly diminished quantity. the trilobites which played so important a part amongst the faunas of lower palæozoic times still occur fairly abundantly amongst the rocks of the devonian system, and there is a very interesting point to be noticed in connexion with them. they seem to have become practically extinct in the succeeding carboniferous period, where few genera are found, and the decadence of the group began in devonian times. in these circumstances it is interesting to note the tendency displayed by the creatures to possess spiny coverings. it is true that _acidaspis_, the most spinose of all trilobites, is abundant in ordovician and silurian strata, and that other spinose trilobites are found there, but the peculiarity of the devonian trilobites is, that genera which were previously smooth, or rarely possessing one or few spines, are found represented by extremely spinose species in these beds,--the spines being developed from all parts of the test, sometimes as a fringe to head or tail, sometimes as prominent projections from glabella and neck segment, and frequently in rows down the body segments. besides _acidaspis_, we find spinose species of _phacops_, _homalonotus_, _cyphaspis_, _bronteus_ and _encrinurus_ in devonian strata, and the occurrence of these forms is so frequent and world-wide, that one might perhaps infer with confidence that an unknown fauna containing many spiny trilobites was of devonian age. [footnote : for an account of these see a. s. woodward's _vertebrate palæontology_.] the abundance of eurypterids has been previously noted. occurring as they do in silurian rocks, they are far more abundant in those of devonian age, and are found indifferently in sediments of old red and devon types. of air breathers, several insects have been found in the strata of different parts of the world. the ordinary marine faunas are otherwise intermediate in character between those of the silurian and carboniferous periods, but there are several characteristic devonian genera, and no one who is acquainted with the peculiarity of the devonian fauna would deny to the devonian strata the right to rank as a separate system, containing a fauna as well marked in its way as that of the silurian system below or that of the carboniferous above. special stress is laid upon this point because it has been suggested that the devonian system should be abolished, and its strata either divided between the silurian and carboniferous systems or referred exclusively to the latter system[ ]. [footnote : the literature of the fauna of the devonian rocks is a rich one. for an account of the devonian rocks of britain, the reader may consult the monograph of the devonian fossils of the south of england by rev. g. f. whidbourne, which is now appearing in the series of monographs of the palæontographical society, and in the publications of the same society he will find a monograph of the eurypterids from the pen of dr henry woodward. the richest devonian fauna is undoubtedly that of the bohemian area, for the work of dr e. kayser has conclusively proved that the stages _f_, _g_ and _h_ of that basin, formerly referred to the silurian, are of devonian age, and an excellent idea of the richness of the devonian fauna may be obtained by studying the descriptions of the fossils from those stages which have appeared and are appearing in barrande's classic work.] chapter xviii. the carboniferous system. _the classification._ the british rocks of the carboniferous system have been classified according to their lithological characters, but as the classification has been altered from time to time, we may use that which seems most acceptable to the majority of british geologists at the present day. according to this, the beds are grouped as below:-- { { ardwick stage upper carboniferous { coal measures { pennant stage { { gannister stage { millstone grit lower carboniferous { carboniferous (mountain) limestone { series. the lower carboniferous beds have been further subdivided into:-- yoredale series or upper limestone shales, mountain limestone, lower limestone shales, with sandstones and conglomerates, but as these lithological types are found to be very variable when traced laterally for comparatively short distances, it is found more satisfactory to use the terms in a purely lithological sense rather than with chronological significance. the somewhat abnormal development of the higher portions of the carboniferous rocks of britain renders the local classification only partially applicable in other regions, and as our knowledge progresses, a palæontological classification will probably be adopted. this has already been done with the more purely open-water sediments of russia and eastern asia, where the development of the beds is more normal. there the rocks are classified as under:-- upper carboniferous or gshellian, middle carboniferous or moscovian, lower carboniferous, and as this classification has already been found to be applicable over rather wide areas, it is almost certain that, as in the case of the rocks of other systems, it will prove more serviceable than one which is mainly (though not quite exclusively) based upon vertical variation of lithological characters, especially as the carboniferous rocks over large tracts in north america possess faunas which are similar to those which have been discovered in russia, eastern asia and north africa. _description of the strata._ the variations in the lithological characters and fossil contents of the british carboniferous strata when traced from north to south have been so frequently described, and utilised as a means of illustrating the indications as to local variations in physical conditions which are supplied by those strata, that little need be said upon the subject. the restoration of the physical geography of carboniferous times over the british area will be found in a chapter by the late professor green in the work upon _coal_ by various professors at the yorkshire college of science and also in prof. hull's _physical history of the british isles_. some modifications must be made in these restorations as the result of recent research, the principal being caused by discoveries amongst the carboniferous rocks of devonshire. taking the strata in vertical succession, we find evidence of the occurrence of a complete marine period (the second great marine period) between the second and third continental periods. the first shallow-water phase over a great portion of the british isles is marked by thin terrigenous sediments, indicating that the period was a brief one; it was followed by the deep-water phase, probably of some length, lasting through the greater part of the remainder of lower carboniferous times; while the concluding shallow-water phase was lengthy as compared with that of the beginning of the period, and is marked by the accumulation of the great thickness of deposits belonging to the millstone grit and coal measures. there is no doubt, however, that in some parts of the british area minor changes produced local terrestrial conditions during the period, and accordingly we find that the deepest water deposits of the system in britain are succeeded by an unconformable junction with the sediments of the upper portion of the system. the general change in the lithological characters of the beds of the lower carboniferous division when traced from south to north is shewn in the following diagram (fig. ). it will be seen that the land and open sea areas were in the respective positions which they occupied during devonian times, but that as the result of greater submergence, with which the accumulation of sediment did not keep pace, the shallow-water marine deposits of devonian age are in devon replaced by open-sea deposits[ ], while shallow-water marine deposits further north replace the anomalous deposits which were found there during the devonian period. [footnote : the radiolarian cherts of the lower carboniferous rocks of devon, and the associated sediments, together with the unconformity between these and the upper carboniferous beds are described by messrs hinde and fox, quart. _journ. geol. soc._, vol. li. p. .] [illustration: fig. . _a._ radiolarian cherts of devon. _b._ mountain limestone of central england. _c._ mechanical sediments of northern england. _d._ freshwater deposits of southern scotland. o.r. older rocks. ] owing to the accumulation of thick masses of sediment, the lower carboniferous sea of the north of england appears to have been largely silted up, and although the organic deposits of the south are so thin that they did not render the sea shallow in that region, the general level of the lower carboniferous floor of the south was also uplifted, and actually converted into land, as the result of the upward movement which took place in devonshire and tracts of france; and owing to silting up in the north, and elevation in the south, a general plane surface was produced over very extensive areas, not only in britain but upon the continent, upon which the peculiar deposits and accumulations of upper carboniferous times were laid down, sometimes in shallow water, sometimes upon the land, and often under conditions which cannot at present be determined with accuracy. that the deposits of the millstone grit and coal measure epochs were to a large extent laid down in water is admitted by all, and in the case of many of the deposits of the millstone grit, and some thin deposits of the coal measures, it is equally clear that the water area was part of an expanse of ocean, for we find marine fossils, as corals, crinoids, and cephalopods, in these beds. associated with them in the coal measures are other beds in which the ordinary carboniferous genera of marine invertebrates are absent, and their place is taken by shells which bear much resemblance to the modern fresh-water mussel, and it has been maintained with good reason that as the ordinary marine forms are rarely or never mixed with those resembling recent fresh-water shells, the latter are truly fresh-water[ ]. if this be so, many of the mechanically formed sediments of the coal measures were of fresh-water origin, laid down in shallow lagoon-like expanses, probably shut off from the main ocean by a narrow portion of intervening land, which was occasionally destroyed, thus permitting incursions of salt-water when some of the ordinary marine invertebrates of the period obtained a temporary footing in the area. [footnote : for further information upon this subject the student should consult the introduction to a monograph on _carbonicola_, _anthracomya_ and _naiadites_ (the shells in question) by dr wheelton hind, being one of the monographs of the palæontographical society.] there is not only a difference of opinion as to the mode of accumulation of many of the mechanical sediments of the coal measures, but also as to that of the coal-seams which accompanied them. two different theories have been put forward to account for these coal-seams, which are usually spoken of as the drift theory and the growth-in-place theory. according to the former, in its extreme application, coal is an aqueous deposit formed by the settlement of drifted masses of vegetation upon the floor of a water-tract, while those who push the growth-in-place theory to its extreme limits maintain that coal is the result of growth of vegetation upon the actual site where the coal is now found. much apparently conflicting evidence has been advanced by the advocates of the two hypotheses, and special cases of coal-formation have been appealed to by each in support of their views; thus the existence of coal composed largely of bodies which resemble the spores of modern lycopods,--objects of so resinous a nature that they float on the surface until they are decomposed,--is cited by the upholders of the growth-in-place theory, while the supporters of the other hypothesis can point with equal force to the occurrence of the finely divided carbonaceous mud containing remains of fishes which gives rise to cannel coal in some places. one of the main assertions in support of the growth-in-place theory was that of the supposed universality of 'underclays' or old surface soils beneath all coal-seams, but though these are common, they are far from universal. it is impossible to do justice in small compass to this question of coal-formation, but it may be pointed out that much of the difference of opinion can be understood if it be remembered that the term 'coal' is rather a popular term which has been admitted into scientific terminology, and therefore used somewhat loosely, than a strictly scientific term applied to a definite substance, and accordingly, just as at the present day we find carbonaceous substances growing in one place on land to form peat, in other places on a tract sometimes dry and sometimes submerged, to form the carbonaceous deposits of the cypress-swamps, and once more accumulated beneath the shallows of a sea as a sediment to form the carbonaceous muds of the ocean margins where the mangroves grow, so the diverse substances which are included under the general term coal may have accumulated in one place on land, in another beneath water, and in a third on an area alternately dry and submerged. this is not a question of great importance; the important point is that accumulations of vegetation on a fairly large scale are found at the present day on plains, for even if they grow on mountain regions, the deposits are readily denuded before they are covered up, and also it must be noted that a moist climate is necessary for the growth of much vegetation. the conclusion that the accumulations of coaly matter were formed on plains is borne out by their great horizontal extent as compared with their thickness, and it is now generally agreed that the coal vegetation which is found in the normal coal-measures was essentially a swamp vegetation. an attempt has been made to prove that an upland vegetation of very different character existed contemporaneously with it, but reasons will be given in the sequel for concluding that this supposed upland carboniferous flora is everywhere of later date. the later shallow-water phase of carboniferous times, as already stated, was unusually long, it was also very widespread, and appears to have been accompanied over wide areas by humid conditions during its continuance, and accordingly the marsh conditions which existed during upper carboniferous times were probably on a larger scale than that of similar conditions before or after. special stress is laid upon this fact, as it is a good illustration of the view which seems to be gaining ground, that every period possessed peculiar conditions never to be repeated, which must have left their impress upon the character of the sediments. though the conditions above described were widespread, they were naturally not universal, and accordingly in many parts of the world, as previously stated, we find true marine deposits of upper carboniferous times, though even these were sometimes replaced during part of the epoch, by conditions which were favourable for the formation of coal-seams in those places. interruption in the continuance of a humid temperate climate over the regions of north-west europe is also suggested by the discovery of deposits which are maintained to be of glacial origin amongst the coal measures of france[ ]. [footnote : for an account of the numerous volcanic products see sir a. geikie's work on "the ancient volcanoes of great britain."] _the floras and faunas._ the flora of the carboniferous rock is so noteworthy that the period has been termed the period of cryptogams; the remains of ferns, horsetails, and clubmosses predominate, and many of the forms reached a gigantic size. though the floras of the various stages are marked by a general resemblance, there are differences which enable the palæobotanist to ascertain the stratigraphical position of the beds by reference to the included plant remains, and a considerable number of successive floras have been described[ ]. the invertebrate fauna does not differ on the whole very greatly from that of devonian times, though the trilobites are now becoming rare, and the mollusca assume a more prominent position as compared with the brachiopods. corals occur in abundance in the calcareous deposits of the period, and frequently give rise to sheets of reef-formation, but the foraminifera and crinoidea certainly play the principal part as limestone-producers, and the influence of the latter in giving rise to great masses of limestone which are frequently used for ornamental purposes is too well known to need more than passing reference. the air-breathers have also been detected in greater abundance, though they are rare, when we consider the comparatively favourable conditions for their preservation presented by the coal measure rocks. myriopods, arachnids, insects and pulmoniferous gastropods have however been found with tolerable frequency. the danger of arguing from imperfect data is well illustrated by the great addition to our knowledge of the insect-fauna of these times due to the exploration of the beds of one small coal-field, that of commentry in france, of which the insects have been described by m. c. brongniart. the vertebrates are represented by a considerable variety of fishes, and less abundant though tolerably numerous remains of amphibia, which occur in the carboniferous rocks of the north of england, ireland, france, north america and elsewhere. [footnote : consult kidston, r., "on the various divisions of the carboniferous rocks as determined by their fossil flora," _proc. roy. phys. soc. edin._, vol. xii. p. .] the existence of definite zones of organisms in the case of the carboniferous rocks has been denied, and it appears to be considered by some that the carboniferous rocks were accumulated so rapidly as compared with rocks of some other systems that the fauna remained very similar throughout. it is very doubtful if this was so. in the case of other systems, the division into zones has only been accomplished by means of more detailed researches than those which have been conducted amongst the carboniferous rocks of britain: again, the occurrence of successive floras suggests that there may have been a similar succession amongst the faunas, and finally we find that zonal division has been carried on to some extent amongst the carboniferous strata of other regions. the following classification of the russian type of sediment may prove useful, as an indication of the possibility of more detailed separation of our own beds:-- { beds with _spirifera fascigera_, _spiriferina_ gshellian { _saranae_, &c. (with _fusulina_ and { beds with _producta cora_, _p. uralica_, _archimedipora_) { _camarophoria crumena_, &c. { beds with _syringopora parallela_ and { _spirifera striata_. moscovian { stage of _spirifera mosquensis_. { stage of _spirifera kleini_. { coals, sandstones and shales with _noeggerathia_ lower carboniferous { _tenuistriata_ and _producta_ { _gigantea_. { stage of _producta mesoloba_. the marine fauna of the upper carboniferous beds, which is so poorly represented in britain, but is well developed in spain, russia, asia and north america, is largely characterised by the abundance of foraminifers of the genus _fusulina_ and _fusulinella_ and of bryozoa of the genus _archimedipora_. it is very desirable that the truly marine fauna of the _spirorbis_ limestone and other marine bands of the british coal measures should be carefully studied to see if they present any close relationship with that of the gshellian beds[ ]. [footnote : a good idea of the general characters of the carboniferous fauna of britain will be obtained from an examination of professor phillips' _geology of yorkshire_, part i., and mr (now sir f.) m^{c}coy's _carboniferous fossils of ireland_, while the nature of the european fauna is well illustrated in prof. de koninck's well-known work _description des animaux fossiles qui se trouvent dans le terrain carbonifère de belgique_. for an account of the characters of the marine fauna of the upper carboniferous rocks the reader should consult the work on geology and palæontology published by the geological survey of the state of illinois in .] chapter xix. the changes which occurred during the third continental period in britain; and the foreign permo-carboniferous rocks. at the close of carboniferous times a marked change took place in the nature of the earth-movements. the prevalent depression which occurred over the british and adjoining regions during carboniferous times was replaced by upward movement, accompanied by orogenic folds, which once more brought on continental conditions and developed a series of mountain ranges. the change is marked even at the close of carboniferous times by the abnormal red sandstones of the uppermost part of the carboniferous system which are found around whitehaven in cumberland and rotherham in yorkshire, as the whitehaven sandstone and rotherham red rock. these movements continued through permian and triassic times, and it is to them and to the climatic conditions of the periods, that the anomalous nature of the permo-triassic deposits is largely due, as will be shewn in the succeeding chapters. at present it is our purpose to call attention to the effect of these movements upon the sediments which had been deposited previously to their occurrence. over the british area, two different systems of orogenic movement can be detected, producing folds of which the axes run approximately at right angles to one another. one of these, of which the pennine system is the best representative in britain, caused the production of elevations having axes in a general north and south direction, and we may therefore speak of it as the pennine system of movement, while the other, which gave rise to folds running in an east and west direction, is well represented in the mendip hills, and may be therefore termed the mendip system, though it is more widely known as the hercynian system, as, on the continent, the rocks which are greatly affected by it form the foundations of the region occupied by the ancient hercynian forest. the effects of these systems were in the main similar; they resulted in the uplift of parallel belts of country to form hill-ranges with intervening lowlands, but when studied in detail the movements are seen to be of a different character. the pennine system of movements was of a type which is familiar to the geologists as developed in the great basin region of the western territories of north america, and produced what is spoken of as basin-range structure. the movements were of the nature of direct uplift, causing fracture, only accompanied by folding in a minor degree, and accordingly the hills are composed of terraced scarps, with one gently sloping side, and one steep scarp-side, the latter on the upthrow side of the fault, as seen in fig. . in the mendip system, the folds were of the alpine type, which is a familiar product of lateral pressure, consisting essentially of overfolds, though these are often complicated by reversed faults. of the pennine system, the pennine chain itself furnishes the most noteworthy example in britain, but we have indications of other folds of this system, such as that which runs from the lake district to the ayrshire coast, which is partly concealed as the result of other movements, and a still more marked one, in the rocks of the malvern hills. [illustration: fig. . _a a´_. one stratum displaced by faults _f f_. _h._ hills.] the mendip system is well shewn in the mendip hills, but the remains of a still more important anticline are seen in south devon and cornwall, separated from the mendip hills by the great syncline of devon. another parallel anticline runs from lancashire to yorkshire at right angles to the pennine chain and separates the coal-field of cumberland and that of northumberland and durham, from those of south lancashire, and yorkshire, notts, and derbyshire. on the european continent the ural chain is the most important uplift of the system of which the pennine chain forms a minor representative, while the hercynian system has caused the compression and stiffening of many of the carboniferous and earlier rocks which now rise to the surface in many parts of central europe. the extensive continental area which was the result of these uplifts not only determined the formation of abnormal deposits, but allowed the occurrence of a long period of time subsequently to the close of the carboniferous period, of which few deposits now exposed in europe are representative, and we must accordingly seek other regions in order to find typical representatives of this _permo-carboniferous_ period, of which the strata developed in the salt range of india have been most carefully worked, especially by dr waagen, though marine sediments of the period are known elsewhere, as in spitsbergen, the ural mountains, china and australasia; and a group of somewhat anomalous sediments of this age in parts of india, australia and south america is of peculiar interest, on account of the insight as to the climatic conditions of the times which it affords. _the permo-carboniferous rocks._ in the salt range of the north-west of india an interesting series of sandstones alternating with limestones rests unconformably upon lower rocks. the sandstones are known as the speckled sandstones, while the limestones are termed the _productus_ limestones. the lower and middle speckled sandstones are succeeded by the lower _productus_ limestone which is separated from the lower division of the middle _productus_ limestone by the upper speckled sandstone; these are all of the permo-carboniferous period, while the upper part of the middle _productus_ limestone and the upper _productus_ limestone belongs to the permian period. the fossils, largely invertebrates, are intermediate in character between those of carboniferous and permian ages. similar fossils are found in the marine permo-carboniferous beds of the other areas which have been named above. the lower speckled sandstone is of interest on account of the occurrence of boulder-beds within it, and this division of the sandstone has been correlated with the lowest (talchir) stage of the permo-carboniferous strata of other parts of india, while the other speckled sandstones and those divisions of _productus_ limestone which are referred to the permo-carboniferous are correlated with the higher divisions of other parts. special mention is made of the talchir division, on account of the occurrence therein of boulder beds which have long been known, and whose glacial origin was inferred by dr w. t. blanford forty years ago. the accumulations shew signs of having been deposited in water, but the existence of large subangular, sometimes striated boulders therein, which must have come from distant sources, and the occasional occurrence of striated rock surfaces on the strata upon which the talchir beds repose unconformably points to ice-action; this would not be so very remarkable if it were an isolated case, though sufficiently so, from the comparative nearness of the region to the equator; but researches conducted in different parts of the southern hemisphere have brought to light similar, and sometimes even more striking evidences of glacial action in widely distinct regions[ ]. in australia they have been found in new south wales, victoria, south australia, east australia and tasmania; the dwyka boulder-conglomerates of south africa and certain deposits of similar character discovered by prof. derby in southern brazil have been referred to the same period, and their glacial origin has also been inferred. this widespread distribution of deposits which are generally contemporaneous, of which the glacial origin may now be taken as established, is extremely remarkable, and must be taken into careful consideration by those who put forward theories framed to account for former climatic changes. [footnote : the reader will find an excellent account of the permo-carboniferous glacial deposits in a paper by prof. edgworth david, entitled "evidences of glacial action in australia in permo-carboniferous time" (_quart. journ. geol. soc._ vol. lii. p. ). in this paper other glacial beds besides those of australia are noticed.] _the flora and fauna._ the flora of the permo-carboniferous beds has caused as much discussion as the question concerning the origin of the boulder-deposits. in the southern hemisphere, the permo-carboniferous rocks of those countries which have yielded boulder-beds also contain remains of a flora which is now known as the _glossopteris_ flora, from the prevailing genus, which is associated with other genera, such as _gangamopteris_. these fossils appear to be ferns, though their modern allies have not been indicated with certainty; associated with them are rare cycads and conifers. the _glossopteris_ flora is markedly contrasted with the coal-measure flora of the northern hemisphere with its giant lycopods. moreover _glossopteris_ appears in the northern hemisphere in rocks of later date than the permo-carboniferous period. it has been suggested that the _glossopteris_ flora originated in a continent in the southern hemisphere, on which the boulder beds were also formed in isolated water areas, and that some of the forms migrated northwards. to this continent the name gondwanaland has been applied by prof. suess, from the _gondwana_ series of the permo-carboniferous rocks of india, in which the _glossopteris_ flora is found, and it has also been maintained that the southern _glossopteris_ flora was contemporaneous with the northern flora of ordinary coal-measure type, though whether this was so to any extent remains to be proved, for the beds containing the _glossopteris_ flora are distinctly newer than any which have furnished a typical northern coal-measure flora. in any case, the change of floras between coal measure and permo-carboniferous times is very marked, and when taken in connexion with the widespread glacial deposits, is one of the most striking phenomena displayed by the rocks of the stratified column[ ]. [footnote : for an account of the glossopteris flora and its geological relations, consult seward, a. c., _science progress_, january, , p. .] the fauna has already been noticed. it consists of brachiopods, some of which are of peculiar genera. the general similarity of the faunas in regions so remote as spitsbergen, the ural mountains, india, and new south wales, indicates an extensive sea during the period. it can hardly be supposed that the fauna of permo-carboniferous times has been completely described, for the fossils of one or two areas only have been made known to us with any degree of fulness, and when the permo-carboniferous and marine permian faunas are as well known as those of triassic times (and the latter have only been fully described very recently) there is no doubt that the important break which was at one time supposed to exist between palæozoic and mesozoic faunas will be filled in satisfactorily[ ]. [footnote : the permo-carboniferous beds are described in messrs medlicott and blanford's _geology of india_, second edition (edited by mr r. d. oldham), and figures of some of the important fossils given therein. for fuller information the reader should refer to waagen's account of the salt range fossils and feistmantel's description of the plants in the _memoirs of the geological survey of india_.] chapter xx. the permian system. _classification._ it has already been observed that as the result of the pennine and mendip systems of earth-movement, the carboniferous rocks of britain are succeeded by a marked unconformity, and that the rocks of the succeeding permian and triassic systems of britain shew an abnormal development. the principal areas where permian rocks are found are on either side of the pennine chain in the north of england, but sporadic exposures of rocks of this age are found in some of the midland and southern counties. the permian rocks have been well studied in germany, and the german names are sometimes adopted in britain, and the following comparison will prove useful:-- britain. germany. magnesian limestone magnesian limestone } zechstein. marl slate kupferschiefer } lower permian sandstones rothliegende. the term zechstein has been applied in a somewhat different sense by different writers, but the one given in the table appears to find most favour. in a region which was essentially continental, considerable variations in the lithological characters of the rocks may be expected, when the strata are traced laterally, but we nevertheless find that the differences are not so great as was formerly supposed to be the case when certain red sandstones lying above recognised permian strata in the district on the west side of the pennine chain towards its northern extremity were also referred to the permian; these sandstones (the st bees sandstones) are now generally admitted to be of triassic age, and comparison between the rocks on opposite sides of the pennine chain is much simplified, as seen below. west side. east side. thin magnesian limestones and marls magnesian limestone hilton shales marl slate penrith sandstone and brockrams lower permian sandstones. _description of the strata._ on the east side of the pennine chain, the lower permian sandstone is an inconstant deposit often consisting of yellow false-bedded arenaceous strata. the marl slate is an argillaceous shale, often containing bituminous matter, and yielding several fish-remains and some plants; it is usually only a few feet in thickness. the magnesian limestone is typically developed in durham as a yellow or greyish limestone containing a variable percentage of carbonate of magnesia; when traced southward, it alters its characters, becoming mixed with mechanical deposits, and some chemical precipitates in places, so that at mansfield it appears as a red sandstone with grains cemented by a mixture of carbonates of lime and magnesia; and, like the rest of the permian strata, it has disappeared when we reach nottingham. in addition to the southward thinning of the permian beds of this area, there is some evidence of their disappearance in a westerly direction, though, as the present strike of the beds is nearly north and south, the indications of this are less convincing. on the east side of the pennine chain, the main difference observable is the relative thickness of the major divisions. the lower permian sandstones have thickened out considerably, while the reputed representatives of the magnesian limestone are thin. the penrith sandstone is of considerable interest. it contains in places, as near appleby, thick deposits of breccia consisting of angular fragments chiefly composed of carboniferous limestone, which in many cases have undergone subsequent dolomitisation, embedded in a matrix of red sandstone. this breccia is known as brockram. many beds of the penrith sandstone are composed of crystalline grains of sand, due to deposition of silica in crystalline continuity with the quartz of the original grain after the formation of the deposit; of more significance, for our present purpose, is the presence of other accumulations of the sand, in which the individual grains often approach the form of spheres, thus resembling the 'millet-seed' sands of modern desert regions. the hilton shales are grey sandy shales, with plant remains, and above them are variable deposits including thin magnesian limestones which have yielded no fossils. the isolated permian deposits of the midland and southern counties of england consist of red marls and sandstones with occasional breccias, and in the absence of fossils, their exact position in the permian series is still unknown. the german permian rocks resemble those of britain, especially as seen in durham, in many particulars, and give indications of formation under physical and climatic conditions generally similar to those which were then prevalent in the british area. at stassfurt, in germany, the less soluble constituents of ocean water are accompanied by a great variety of salts:--chlorides, sulphates and borates; and the very soluble salts of potassium and magnesium known as the abraum salts are found in abundance as well as the less soluble salts of sodium and calcium. the occurrence of these very soluble salts is so infrequent on a large scale among the rocks of the geological column, and the matter is one of so great theoretical import, that it is necessary to take special note of their presence in the permian strata. the frequent existence of chemical deposits in the permian rocks of n.w. europe, the formation of red sandstones, and the dolomitisation of limestone beds and fragments of pre-existing limestones point to inland seas of a caspian character, while the evaporation necessary for the formation of the precipitates also indicates a fairly warm temperature. the presence of millet-seed sands, in very lenticular patches, suggesting former sand-dunes, and the occurrence in places of breccias (like some parts of the brockram) almost devoid of matrix, piled up against pre-existing cliffs, recalling screes of modern times, give almost certain evidence of the occurrence of land tracts most probably of desert character, during part of the period of accumulation of the materials of the permian rocks. the fossil evidence supports this view, and geologists are mostly agreed that the permian rocks of north-west europe were accumulated in an area of desert character, occupied in part by inland seas, though there is much difference of opinion as to the extent of these seas, some geologists holding that a number of isolated sheets of water were necessary to produce the distribution and character of the accumulations. it is still a vexed question with british geologists how far the pennine ridge stood up as land during the period, but leaving this and other minor considerations out of account, it may be noted that the similarity of deposits in the different areas, whether we examine the order of succession, the lithological characters or the included fossils, suggests communication between the water tracts of different regions, though this communication need not have been more than a series of straits, or comparatively narrow belts of water[ ]. [footnote : it should be mentioned that some writers have inferred the evidence of glacial conditions over parts of the british area, on account of the resemblance of some of the permian breccias to recent glacial deposits. the question is still _sub judice_. it is not necessarily opposed to the existence of desert conditions, if the mountains were sufficiently high, for the wahsatch regions adjoining the basin region of n. america have been glaciated.] the extensive development of permian and triassic rocks with terrestrial characters in the southern hemisphere also, and the absence of newer deposits in many places, suggests that the land areas of these times in that hemisphere have largely remained such ever since, in which case, the permo-triassic series of movements produced a marked direct effect upon our present continental areas, and at any rate produced an indirect one upon the british land tracts. the presence of anomalous deposits of permian age over wide areas need not be surprising, but it would be indeed remarkable if no ordinary marine type of permian rocks was known, and the researches of recent years have proved that this type is extensively developed, in eastern europe, asia, and north america, where permian rocks consisting of limestones, with a greater or less admixture of mechanical deposits, occur in some abundance. the studies of waagen and others in india have given us the farthest insight into the nature of these beds. below is a general classification taken from waagen's work:-- salt range. germany. base of trias } unfossiliferous shale and } sandstone } passage beds into trias top beds of upper _productus_ } limestone } cephalopoda beds of upper } gypsum beds _productus_ limestone } middle division of upper } _productus_ limestone } zechstein (in restricted sense) lower division of upper } _productus_ limestone } upper division of middle } weissliegende and kupferschiefer _productus_ limestone } middle division of middle } rothliegende. _productus_ limestone } it will be seen that in the salt range there is a complete passage from the permo-carboniferous strata through the permian into the trias, and the detailed work which has been carried out by waagen and others amongst the rocks of the salt range must make this, for the present at all events, the type area for the marine development of the strata of permo-carboniferous and permian ages. _the permian flora and fauna._ the permian flora presents some difficulties. the flora of the zechstein consists largely of ferns and conifers, but that of the rothliegende of germany has been compared with that of the carboniferous, and if a true permian flora of the northern hemisphere has many forms of carboniferous affinities, the presence of the glossopteris flora in permo-carboniferous rocks of more southerly regions seems to imply its origin there and _slow_ migration northwards. it must be noted, however, that the rothliegende has been divided by some geologists into an upper and lower division, of which the lower is actually referred to the carboniferous system. all that can be now said is, that our knowledge of the floras of permo-carboniferous and permian times is still incomplete, and that the difficulties will no doubt be cleared up as the result of further work. the invertebrate fauna of the north-west european permian deposits is chiefly noticeable on account of the paucity of species, though individuals are often abundant. the shells are also sometimes stunted and occasionally distorted. these characters bear out the supposition that the aqueous deposits were laid down in inland seas of caspian character and not in the open ocean. polyzoa, brachiopods, and lamellibranchs predominate, but other groups are found. the vertebrates consist of forms of fish, amphibia and reptiles, and the permian rocks are the earliest strata in which the remains of true reptilia are known to occur with certainty. the reptiles belong to the orders anomodontia (theromora) and rhynchocephalia, of which the former is exclusively permian and triassic, while the latter is abundant in the strata of those periods, but is represented at the present day by the genus _sphenodon_ of new zealand. the amphibia belong to the order labyrinthodontia which ranges from carboniferous to lower jurassic, but the members of the order are most abundant in permian and triassic strata, and these periods may be spoken of as the periods of labyrinthodonts. a few words must be said of the fauna of the truly marine permian beds. it is much richer than that of the abnormal deposits of north-western europe, and its study is important as furnishing another link between palæozoic and mesozoic life. many palæozoic genera pass up into the permian rocks, and, as will be ultimately seen, several occur in those of the triassic system, and one or two even in the basal jurassic strata, though mesozoic forms predominate in the lower jurassic rocks, and there is a fairly equal admixture of forms usually considered as palæozoic and of those generally regarded as mesozoic in triassic rocks, while the palæozoic forms still predominate over the mesozoic in the permian strata. along with these characteristic palæozoic genera, it is interesting to find representatives of more than one genus of the tribe of ammonites, which is to take so prominent a place in the fauna of the mesozoic rocks, amongst the true marine permian sediments of india and other areas. the announcement of the contemporaneity of ammonites with fossils regarded as exclusively palæozoic was received with considerable doubt, but this contemporaneity is now clearly established, and need not be regarded as in any way anomalous. with the deposition of the permian rocks, palæozoic time comes to an end, but as already remarked there is no marked and sudden change to characterise it. had our classification been originally founded on study of the indian rocks instead of those of britain, and similar terms adopted, the line of demarcation between palæozoic and mesozoic rocks would probably have been drawn below the permo-carboniferous deposits, and if it had been based on study of other areas, perhaps elsewhere. the palæontological break is purely local, and it is of the utmost importance that it should be recognised as such, and that it should not be considered that division into palæozoic and mesozoic implies some great and widespread change which occurred between the times covered by the deposits of each of these great divisions[ ]. [footnote : the permian fossils of britain are described by professor king in the monographs of the palæontographical society (the brachiopods by dr davidson in the monographs of the same society). for a general account of the marine type the student may consult the second edition of messrs medlicott and blanford's _geology of india_. for information concerning the permian volcanic rocks see sir a. geikie's _ancient volcanoes of great britain_.] chapter xxi. the triassic system. _classification._ the term triassic has been applied to these rocks on account of the threefold division into which those of germany naturally fall. these three divisions are:-- keuper, muschelkalk, bunter; but above the keuper beds we find a group of deposits of some importance, which shew affinities with both triassic and jurassic rocks, which may be looked upon as true passage beds, though they are generally placed in the triassic system. they are known as rhætic or locally in britain as penarth beds. the muschelkalk is usually considered to be unrepresented in britain, and accordingly the british deposits may be, and are usually grouped as under:-- rhætic or penarth beds keuper { keuper marls { keuper sandstones [muschelkalk] absent { upper red and mottled sandstones bunter { bunter pebble beds { lower red and mottled sandstones. the threefold grouping has been applied more or less universally, but when used outside the north-west european area, it loses its significance, as the conditions which enable one to differentiate the rocks of the three divisions were naturally only prevalent over a limited area. _description of the strata._ the british triassic rocks possess a certain sameness as regards their general characters, consisting mainly of mechanical sediments coloured red by peroxide of iron, with occasional chemical precipitates of rock-salt and gypsum. they have a wider distribution over britain than have the permian rocks, and the lithological characters of the different subdivisions do not as a rule vary to a remarkable degree when traced laterally. the differences in detail in the characters of the various deposits are noteworthy, and an explanation of the exact origin of some of these abnormal deposits which will satisfy everyone is not yet forthcoming. leaving the details out of consideration for the moment, and looking at the general aspect of the deposits, the prevalence of conditions generally similar to those which existed over the british isles in the preceding permian period is decidedly indicated by the nature of the strata, though the continental conditions appear to have been more widely established over our area, as shewn by the general absence of any calcareous deposits resembling the magnesian limestone. we find chemical precipitates, millet-seed sandstones, and scree-like breccias in the british triassic rocks as well as in those of permian age, and the paucity of a marine invertebrate fauna in the triassic rocks of britain is even more apparent than in the permian strata. it is only at the extreme close of the triassic period, during the deposition of the rocks which are admitted on all hands to be of rhætic age, that we note the incoming of those marine conditions over our area, which prevailed so extensively, with few local exceptions, during the remainder of the mesozoic and the early part of tertiary times; the rhætic beds, in fact, mark the commencement of the third marine period. referring to the strata in further detail, we may proceed to consider the character of the different subdivisions in the order of their formation, commencing as usual with the oldest. the bunter deposits rest in places upon those of permian age with an unconformity at the junction, but as these unconformities occur frequently among the british triassic rocks, it is doubtful whether this unconformity marks more than very local change of physical conditions. the lower and upper divisions of the bunter sandstone consist of false-bedded red and variegated sandstones, and there is no great difficulty in explaining their formation in desert areas with tracts of water, but the great change which marks the appearance and disappearance of the middle division, the bunter pebble beds, requires some explanation, for the contrast between the lithological characters of the rocks of this division and those of the rocks appertaining to the preceding and succeeding division is very marked. the matrix differs, but the main difference is the abundance of pebbles, mostly of fairly uniform size, well rounded, and largely consisting of liver-coloured quartzite. much difference of opinion exists as to the exact origin of these pebble beds, and the source of the pebbles, but without entering into this vexed question, it may be remarked that the agency of rivers has been somewhat generally invoked to account for their transport, and the conditions during their accumulation need not have been very different from those which are now found in northern india where the torrential rivers of the south side of the himalayan chains debouch upon the plain, and spread an abundant deposit of well-worn pebbles over the finer silts which were previously laid down thereon. the junction of the bunter and keuper beds requires a short notice. it is usually if not always an unconformable one in britain, and it is generally assumed that the absence of the muschelkalk of the continent is due to the presence of land undergoing denudation in britain during the time when the muschelkalk was elsewhere deposited, though it is quite possible that the muschelkalk epoch is represented in britain not only by the time which elapsed when the unconformity was being impressed on the rocks, but also during the true deposition of the upper part of the bunter beds, or the lower part of the keuper, or both. the keuper sandstones and marls contain a great development of chemical deposits, of millet-seed sands, and of many other features pointing to desert conditions, such as sun-cracks, tracks of animals impressed upon a rapidly drying surface, and pseudomorphs of mud after rock salt in the form of cubes and hopper-crystals; furthermore we find the scree-like breccias at different horizons of the keuper beds where they abut against the old mendip ridge composed largely of mountain-limestone which furnished the fragments, as was the case with the brockrams abutting against the pennine ridge. it must be noted that the chemical precipitates of triassic age consist of the less soluble substances dissolved in ocean water, namely, gypsum and rock salt, whilst the more deliquescent potash and magnesia salts are not represented in britain. turning to these continental beds, we get evidence of a general approach to open sea conditions as we pass away from britain in a south-easterly direction as roughly shewn in the following diagram (fig. ), where _b_ represents the bunter beds, _m_ the muschelkalk, and _k_ the keuper. [illustration: fig. .] it will be seen that the mechanical sediments gradually die out and become replaced by calcareous material as one passes from britain towards switzerland; the muschelkalk is very thin in the east of france and thickens out in germany, while in switzerland keuper, muschelkalk and bunter are alike largely represented by calcareous deposits, and the mechanical deposits are chiefly argillaceous, the only important sandstone being situated at the extreme base of the bunter series. the marine development of the triassic system is naturally the one which is most widely spread, though full appreciation of its importance has only taken place as the result of researches in distant climes of recent years. it is found in southern europe, in spitsbergen, in considerable tracts of asia, including india, and along the pacific coast region of north america, and everywhere possesses much the same characters. it will be seen from the above remarks that the physical conditions which prevailed in the continental area of triassic times which is now partly occupied by the british isles are most closely represented by those of the desert regions of central asia, hemmed in by the mountain ranges which intercept the vapour-laden winds of the oceans, and cause them to precipitate the great bulk of their vapour on the seaward slopes of the mountains, so that they blow over the deserts as dry winds, causing the fall of any large amount of rain to be a rare though by no means unknown event in the desert regions. _flora and fauna of the period._ the triassic flora is essentially similar to that of the higher permian strata, though many of the genera are different. the invertebrate fauna of the british deposits is, as might be expected, very poor until the beds of the rhætic series are reached. in the beds below the rhætics, the principal invertebrate remains are the tests of the crustacean genus _estheria_, though a few obscure lamellibranch shells have been recorded. the vertebrate fauna is of great interest. a number of fishes have been found, the most remarkable of which is the genus _ceratodus_, occurring in the rhætic beds of britain and lower triassic strata of foreign countries. it is closely related to the barramunda of the queensland rivers belonging to the order dipnoi. as in the permian strata, abundance of labyrinthodont amphibians have been discovered, and the reptiles belong to the orders anomodontia and rhynchocephalia. in the rhætic beds of britain and in still lower triassic beds abroad the orders ichthyopterygia and sauropterygia (represented by _ichthyosaurus_ and _plesiosaurus_) are found. the triassic rocks also yield the earliest known mammals, the best known, _microlestes_, occurring in the triassic rocks of britain and the continent. these mammals are now placed in a subclass metatheria of the order monotremata. the marine invertebrate fauna of the normal triassic rocks presents some points of considerable interest. as already remarked, the fauna may be looked upon as a passage fauna between that of palæozoic and that of mesozoic times, the number of palæozoic forms which pass into the trias being approximately comparable with those which appear here and range upwards into higher mesozoic strata. this may be well seen by examining the table given in chapter xxi. of the second edition of sir charles lyell's _student's elements of geology_, in which three columns shew the genera of mollusca common to older rocks, those characteristic of the trias, and those common to newer rocks. amongst the first are _orthoceras_, _bactrites_, _loxonema_, _murchisonia_, and _euomphalus_, in the second column are _ceratites_, _halobia_ (_daonella_), _koninckina_, and _myophoria_, and in the third, ammonites, _cerithium_, _opis_, _plicatula_ and _thecidium_[ ]. [footnote : it has been seen that some of the ammonites appear earlier, namely, in permian strata. _myophoria_ is extremely abundant in the trias, but ranges into newer strata.] the ammonites are largely utilised in the case of the mesozoic strata for separation of these strata into zones, each zone being characterised by some species of ammonite, and the researches of mojsisovics have proved that this zonal subdivision, long adopted for jurassic rocks, is also applicable to those of triassic age[ ]. he gives the following table of the classification of the triassic rocks of the mediterranean province, which is reproduced, as it is founded upon palæontological evidence, and will probably be widely adopted. [footnote : von mojsisovics, dr e., "faunistische ergebnisse aus der untersuchung der ammoneen-faunen der mediterranen trias." _abhandl. der k. k. geologisch. reichsanstalt_, vi. band abtheilung. vienna, .] series zonal divisions --------------+-------------------+-------------------------------------- rhætic | | . zone of _avicula contorta_ --------------+-------------------+-------------------------------------- | | . zone of _sirenites argonautae_ | upper juvavic | . zone of _pinnacoceras | | metternichi_ juvavic | middle juvavic | . zone of _cyrtopleurites | | bicrenatus_ | | . zone of _cladiscites ruber_ | lower juvavic | . zone of _sagenites giebeli_ --------------+-------------------+-------------------------------------- | upper carnic | . zone of _tropites subbullatus_ carnic | middle carnic | . zone of _trachyceras aonoides_ | lower carnic | . zone of _trachyceras aon_ --------------+-------------------+-------------------------------------- | upper noric | . zone of _protrachyceras noric | | archelaus_ | lower noric | . zone of _protrachyceras curionii_ --------------+-------------------+-------------------------------------- | upper muschelkalk | . zone of _ceratiles trinodosus_ muschelkalk | | | lower muschelkalk | . zone of _ceratiles binodosus_ --------------+-------------------+-------------------------------------- buntsandstein | werfener schichten| . zone of _tirolites cassianus_ --------------+-------------------+-------------------------------------- chapter xxii. the jurassic system. the jurassic rocks were formerly separated on account of differences of lithological character into oolites and lias, but it was apparent that the oolites were more important than the lias, and a fourfold division was made into:-- upper or portland oolites } middle or oxford oolites } = malm lower or bath oolites = dogger lias. the lias strata have also been spoken of as the black jura, the lower oolites and part of the oxford oolites as brown jura, and the rest of the oxford oolites with the portland oolites as white jura. as the outcome of a detailed study of the faunas of the jurassic rocks, a further subdivision has been made, partly based upon the original british series, but the divisions are defined with greater accuracy, so that they are applicable over wider areas. they are as follows:-- { purbeckian upper oolites { portlandian { kimmeridgian { corallian middle oolites { oxfordian { callovian lower oolites { bathonian { bajocian { toarcian lias { liassian { sinemurian. many of these series have been still farther subdivided into smaller stages, and the whole differentiated into a number of zones characterised by different forms of ammonites. dr e. von mojsisovics gives thirty-two ammonite zones, of which fourteen occur in the lias, eight in the lower oolites, six in the middle oolites, and four in the upper oolites. _characters of the strata._ the whole of the jurassic rocks and also those of lower cretaceous age may be regarded as having been deposited during the first shallow water phase of the third marine period, but this shallow water phase is represented by strata which are varied owing to numerous marine changes resulting in the production of land at times, and estuarine conditions, shallow water, marine conditions, and somewhat deeper sea conditions respectively at other times, and accordingly the strata of the british isles vary greatly when traced laterally. that the uplifts of the permo-triassic periods produced some effect on the nature and distribution of the jurassic rocks is certain, but it is not quite clear how far the ridges produced by these uplifts were submerged and denuded during the deposition of the main portion of the jurassic strata. viewed broadly, the jurassic rocks of britain may be regarded as consisting of three great clay deposits, the lias, oxford and kimmeridge clays, alternating with the deposits of variable lithological characters, which compose the bajocian, bathonian, corallian, portlandian and purbeckian subdivisions. this essentially argillaceous character of a large part of the deposits of jurassic age is often overlooked, as, owing to their sameness and the comparative paucity of organisms constituting the faunas in the clays, their description in text-books can be given at much shorter length than that of the more variable and highly fossiliferous deposits which separate the clays. the following figure (fig. ) roughly represents the nature of the different divisions of the rocks of this system when traced across england from south-west to north-east. [illustration: fig. . vertical scale: in. = about feet.] it will be seen that the greatest variations in lithological character occur in the bathonian and bajocian beds, and it will be of interest to give some account of the principal variations and to attempt to account for them. in so doing it will be convenient to consider the four major divisions of the jurassic rocks separately, and to enter into particulars concerning the local classification applied to the rocks of these divisions. _the lias._ the british lias deposits are divided into the lower lias, the marlstone, and the upper lias corresponding in general terms only with the sinemurian, liassian, and toarcian. the marlstone is separated from the upper and lower lias on account of the greater percentage of carbonate of lime which it contains, so that the bands of argillaceous limestone are much more marked in the marlstone than in the upper and lower divisions, which consist chiefly of clay. the three divisions possess very much the same characters throughout the country, though the presence of the mendip ridge and its continuation beneath london is marked by the attenuation of this and succeeding strata, and by the conglomeratic character of some of the liassic strata where they abut against it. the british lias, as a whole, seems to have been deposited in a fairly shallow sea at no great distance from the land. it passes down conformably into the rhætic beds, indeed the zone of ammonites (_aegoceras_) _planorbis_, referred by british geologists to the lower lias is included by some continental writers with the rhætic beds, and the plane of demarcation here as in other cases is conventional. _the lower oolites._ of all the british strata, these perhaps cause most trouble to the learner, on account of the different nomenclature applied to the rocks in different parts of england, and the rapid variations in lithological character, when the beds are traced laterally. the following divisions are usually adopted for the beds of the south-western counties where the most marked marine development occurs:-- cornbrash, forest marble, great oolite (with bradford clay), fuller's earth, inferior oolite. of these divisions, the uppermost one, the cornbrash, though thin, retains its characters with great constancy across the island. of the others the forest marble may be looked upon as a local development of the upper portion of the great oolite, and the fuller's earth is a local deposit, so that the inferior oolite and great oolite constitute the important divisions of the lower oolites. the variations in the characters of the rocks may be best shown in tabular form. -----------------+------------------+-------------------+----------------- gloucestershire, | south | n. | &c. | northamptonshire | northamptonshire | yorkshire | | and lincoln | -----------------+------------------+-------------------+----------------- cornbrash | cornbrash | cornbrash | cornbrash -----------------+------------------+-------------------+----------------- great oolite | great oolite | great oolite clay | | (upper part) | great oolite | upper | | limestone | | | upper | estuarine | northamptonshire | estuarine | ............... | ................ | ................. | ................ | | series | series | | lincolnshire | scarbro' | | limestone | limestone | sands | | middle estuarine | | | series inferior oolite | | lower estuarine | millepore oolite | | series | | | | lower estuarine | | | series -----------------+------------------+-------------------+----------------- upper lias | upper lias | upper lias | upper lias -----------------+------------------+-------------------+----------------- the dotted line shows roughly the division between bathonian and bajocian. the changes may be explained very simply if we leave out of account for the moment the development of lincolnshire limestone, with its equivalent the scarbro' limestone, and the millepore series. the beds in gloucestershire and other south-western counties are essentially marine; whilst in northamptonshire and lincolnshire estuarine conditions set in after the deposition of the upper lias, and continued throughout the deposition of the bajocian and lower bathonian beds, being replaced by marine conditions during the formation of the upper bathonian strata, and still further north in yorkshire the estuarine conditions generally prevailed throughout bajocian and bathonian times. these changes point to the existence of land towards the north. the general simplicity is modified by temporary prevalence of marine conditions twice over (during the deposition of the millepore oolite and the scarbro' limestone) in yorkshire, and once (during the deposition of the lincolnshire limestone) in lincolnshire. certain local deposits have not been noticed, but two of them merit brief reference. at the base of the great oolite of oxfordshire is an estuarine deposit of finely laminated mechanical sediment mixed with calcareous matter known as the stonesfield slate, especially interesting on account of its fossils, while a bed with similar lithological characters but with a different fauna occurring at the base of the lincolnshire limestone (of bajocian age) is termed the collyweston slate. neither of these deposits is a slate in the true sense of the word, as they have not been affected by cleavage subsequently to their accumulation, but each has been somewhat extensively used for roofing purposes. the middle oolites are much less complicated though considerable variations arise with respect to the corallian rocks. the oxfordian with callovian consist chiefly of clay, though the callovian of the south of england is represented by calcareous sandstone, with a peculiar fauna which seems to be represented in the lower part of the oxford clay further north, though this callovian fauna has not been everywhere recognised. the corallian of the southern counties consists of limestones with calcareous grits, the limestones being often largely composed of the remains of reef-building corals, and a similar development of the rocks of this series is found in yorkshire, while a local development of the same character is found at upware in cambridgeshire, though in the other parts of the fenland counties the corallian is represented by an argillaceous deposit with corallian fossils known as the ampthill clay. the upper oolites have a tolerably constant base, the kimmeridge clay, usually consisting of laminated bituminous argillaceous material, but the portlandian and purbeckian divisions vary greatly, and are only locally developed, though their absence in some parts of central england is no doubt due to unconformity. the portlandian rocks of the south of england consist of limestones and sandstones which pass further northward into shallower water mechanical deposits often charged with iron hydrate, and the beds disappear in oxfordshire. the purbeckian rocks of the south are also limited as regards area of exposure: they consist of estuarine deposits with some terrestrial accumulations of the nature of old surface soils. representations of the portlandian and purbeckian beds are found in lincolnshire and yorkshire, as arenaceous deposits in the former county and argillaceous ones in the latter. both are marine deposits of a northern type, developed elsewhere in northern european and circumpolar regions, and in these counties we find a complete passage from the jurassic rocks through the cretaceous rocks, but the exact lines of demarcation between the different series of the passage beds are difficult to define. the foreign jurassic rocks of europe and of some parts of asia strongly resemble in general characters those which have been described above as occurring in britain. one of the most remarkable features of the jurassic rocks as a whole, is the absence of the lias over wide areas, the continental period which in britain existed in permo-triassic times is elsewhere frequently replaced by one of liassic age. the jurassic and cretaceous rocks are of interest on account of the evidence which they supply as to the existence of climatic zones in these periods, which run fairly parallel with those at present existing. the late dr neumayr in a paper already cited divides the world during later mesozoic times into four distinct climatic zones, equatorial, north and south temperate and boreal zones (the corresponding austral zone is not known owing no doubt to the extensive sea of south polar regions and our general ignorance of its lands). in europe the mediterranean province belongs to the equatorial zone, the middle european to the north temperate zone, and the russian or boreal to the boreal zone. the last-named is marked partly by negative characters, the absence of certain ammonite-genera and of coral reefs being noticeable, whilst the lamellibranch _aucella_ is very frequent. in the north temperate zone, certain ammonite genera as _aspidoceras_ and _oppelia_ are abundant and there are also extensive coral-reefs. the equatorial zone is marked by the ammonite-genera _phylloceras_ and _lytoceras_ and by the _diphya_ group of _terebratulæ_. it is of special interest to note that the fauna of the south temperate bears closer relationship to that of the north temperate than to that of the intermediate equatorial zone. _jurassic floras and faunas._ the jurassic flora is very similar in its characters to that of the lower cretaceous rocks, and the two taken together afford a decided contrast with that of later palæozoic times, and also with that which succeeds them in the upper cretaceous rocks, which bears a marked resemblance to the existing flora. cycads predominate, accompanied by conifers, and a fair number of ferns and equisetaceæ. the jurassic fauna is specially noteworthy on account of the character of the vertebrata, but some notice of the invertebrates must also be taken. the abundance of corals in the temperate zones has already been pointed out, but the mollusca form the bulk of the invertebrate fauna, lamellibranchs, gastropods and cephalopods being all abundant; of the last-named the ammonites and belemnites contribute most largely. the vertebrates include remains of fishes, amphibia, reptiles, birds and mammals. the jurassic reptilia furnish representatives of some modern orders as the chelonia and crocodilia, but the most important orders are essentially characteristic of later mesozoic times and their representatives abound in the jurassic strata. these are the sauropterygia (including the plesiosaurs), the ichthyopterygia (including the ichthyosaurs), the dinosauria, and the pterosauria commonly known as pterodactyls. no birds have hitherto been discovered in the british jurassic rocks, but the solenhofen slate of bavaria (of kimmeridgian age) has furnished the celebrated _archæopteryx macrura_, which is not only placed in a family but also in an order by itself, the order saururæ. many remains of mammals have been extracted from the estuarine deposits of stonesfield, and the old surface soils of the purbeckian beds; representatives of the monotremata are furnished by the _plagiaulacidæ_ and _tritylodontidæ_, the former family containing the genus _plagiaulax_ of the purbeck beds and the latter, _stereognathus_ of the stonesfield slate. the marsupialia are represented by the _amphitheridæ_, _spalacotheridæ_ and _triconodontidæ_. some forms have been referred to the insectivora, but there is still disagreement concerning the correctness of this reference. before dismissing the subject of the jurassic fossils, attention may be called to a feature which has been frequently commented upon, namely, the general resemblance of the flora and fauna of jurassic times to the modern australian fauna and flora. the explanation which has been offered to account for this resemblance has been given in a preceding chapter, where it was stated that mr a. r. wallace considers, after review of the geological and biological evidence, that australia was severed from the adjoining continental lands in mesozoic times, and that the higher forms of life which on the larger continents have replaced the earlier and lower forms have not succeeded in obtaining a footing in australia, which therefore furnishes us with a local survival of a once widespread fauna. in connection with this matter the actual existence of the genus _trigonia_ (a form peculiarly abundant in jurassic strata and characteristic of mesozoic strata in britain) in the australian sea is of considerable interest.[ ] [footnote : a good account of the british jurassic rocks will be found in mr h. b. woodward's memoir on "the jurassic rocks of britain." _mem. geol. survey_, --.] chapter xxiii. the cretaceous system. _classification._ the rocks of the cretaceous system are conveniently divided into upper and lower cretaceous. the following classification has been widely used for the british deposits, and is founded on lithological characters: { upper chalk with flints } { middle chalk with few flints } chalk upper { lower chalk without flints } cretaceous { chalk marl } { upper greensand { gault { lower greensand lower { wealden cretaceous { hastings sands as the result of examination of the faunas, a more generally applicable classification has been established and is now largely adopted. it is as follows: danian } senonian } upper cretaceous turonian } cenomanian } albian } aptian }lower cretaceous. neocomian } in this classification the neocomian practically represents the wealden and hastings beds, the aptian the lower greensand and the albian the gault, placed according to this classification in the lower cretaceous, while the upper divisions represent the strata above the gault, consisting essentially of chalk in england. _description of the strata._ (i) _the neocomian and aptian beds._ in the south of england the lower cretaceous beds succeed the jurassic rocks with little or no break, and the type of the lower beds is similar to that of the beds deposited during the purbeck age, consisting of estuarine deposits of variable characters, chiefly arenaceous below (the hastings sands) and argillaceous above (the wealden series), though impure limestones are found, largely composed of the shells of the freshwater _paludina_, and much ironstone is developed in places. at the close of neocomian times, the freshwater conditions in southern england were replaced by marine conditions and the lower greensand strata with their marine fauna were deposited in the aptian sea. the neocomian and aptian beds thin out westward, and much more rapidly to the northward, so that both divisions disappear against the now buried ridge which forms a continuation of the mendip axis. north of this they appear in another form. at first the highest aptian beds alone are developed as shore deposits. passing into norfolk lower beds come in until in lincolnshire we get a complete development of the neocomian and aptian beds with a marine facies, though of fairly shallow water character, whilst in yorkshire the two divisions are represented by a deeper water clay, forming the upper portion of the speeton series. there is a consensus of opinion in favour of the neocomian beds of southern britain having been laid down in an estuary of a river flowing from the west over a continent now destroyed. to the north of this river stood the london ridge of the palæozoic rocks, the northern borders of which formed the coast line off which were deposited the sediments of neocomian and aptian ages which occur in northern england. before the deposition of the albian beds a considerable upheaval of some parts of britain occurred, and an unconformity separates the higher cretaceous beds from older strata of cretaceous and jurassic ages, thus complicating the major phases by local changes in the characters of the strata. (ii) _the albian and higher cretaceous beds._ the commencement of the deep-water phase of the third marine period may be said to occur in albian times in britain, reaching its maximum during the deposition of the chalk. the existence of a deeper sea towards the north of england is indicated by the characters of the albian and newer strata. the albian beds of gault consist of a stiff clay in southern england, replaced by coarser mechanical sediments towards the west. as one passes north from the london ridge (which exerted its influence in albian times, after which it was finally buried in sediment) the gault thins out, and becomes gradually replaced by calcareous deposit when it is known as the red chalk which replaces the gault in northern norfolk, lincolnshire and yorkshire. a local unconformity separating the chalk and gault in parts of east anglia points to another local uplift with its accompanying complications in the characters of the strata. after the uplift had ceased, general depression must have occurred, and the various divisions of the chalk were accumulated in a fairly open sea, though, for reasons to be given presently, this was probably of no great lateral extent, save when united with the open ocean, probably in a manner similar to the connexion between the gulf of mexico and the atlantic. the general variations in the lithological characters of the various members of the cretaceous system will probably be rendered clearer by reference to the accompanying diagram (fig. ) representing the variations when traced across england from south to north[ ]. [footnote : for information concerning the british cretaceous beds, see topley and foster, "geology of the weald," _mem. geol. survey_, ; bristow and strahan, "geology of the isle of wight," _mem. geol. survey_, ; lamplugh, "on the speeton clay," _q. j. g. s._, vol. xlv. p. , and "the speeton series in yorkshire and lincolnshire," _ibid._, vol. lii. p. ; barrois "recherches sur le terrain crétacé supérieur de l'angleterre et d'irlande," lille, ; and various papers by messrs hill and jukes-browne, in the _quarterly journal of the geological society_ and _geological magazine_ of recent years. for the scotch deposits consult a paper by prof. judd, _q. j. g. s._, vol. xxxiv. p. , and for those of ireland, see hume, _q. j. g. s._, vol. lii. p. .] [illustration: fig. . ch. chalk. al. albian. ap. aptian. n. neocomian. j. jurassic. ] the clue to the physical geography of britain during cretaceous times is furnished to a considerable extent by study of the foreign deposits. in northern europe the cretaceous beds of england are met with in northern france, and there the characters are generally speaking similar to those of our british deposits. in germany shallower water conditions prevailed, the lower beds gradually disappear, and the upper beds are replaced by mechanical sediments of various degrees of coarseness, becoming on the whole coarser, as one travels eastward, so that in saxony the chalk is partly replaced by arenaceous deposits (the 'quader' sandstones) which are responsible for the remarkable scenery of the elbe district above dresden. in passing northwards, indications of similar change are noted in the deposits of denmark and scania, whilst to the south, we get a complete change in the character of the rocks, after crossing the loire in france, and a similar change is observable in districts lying further east. furthermore, as will be noted more fully in a subsequent paragraph, the character of the upper cretaceous flora indicates the existence of a large tract of land lying to the north and north-west of europe, so that it would appear that the cretaceous rocks of northern europe were deposited in a gulf-like expansion of a western ocean, bounded on the north by scandinavia, on the west by eastern germany, and on the south by a ridge running eastward from the mouth of the loire[ ]. we may speak of this gulf as the chalk gulf. to the south of the presumed ridge the character of the strata alters, and also that of the included organisms. this southern type of cretaceous rocks is one which is very widely spread, being found in europe south of the loire, and of the alps, and in greece and turkey, while it also occurs in the northern parts of africa. the beds of this type are traceable through asia minor into india and to the shores of the indian ocean, indicating the existence of a widespread cretaceous ocean, which is sometimes spoken of as the hippurite-limestone sea, for reasons which will eventually appear. the deposits are largely formed of hard limestone which is very different in its character from the soft chalk of the northern gulf. [footnote : the reader will find the existence of this gulf maintained and supported by a considerable mass of detail in mr a. r. wallace's _island life_.] the climatic conditions which prevailed during cretaceous times were apparently similar in most respects to those of the preceding jurassic period, and as already stated the climatic zones which neumayr defined for jurassic times are also maintained by him to have existed during the cretaceous period. the existence of cold has sometimes been inferred from the presence of large foreign blocks in the chalk, especially at its base, but if these are due to the transport, they might well be caused by masses of floating ice, which are often found at considerable distances from the coast in temperate regions after the break-up of the frost which succeeds an unusually hard winter. the flora and fauna are not suggestive of severe conditions. _the cretaceous flora and fauna._ it has been noted in the last chapter that the gymnospermous flora of the jurassic period, in which cycads form a considerable percentage of the whole flora, was prevalent in lower cretaceous times. in the upper cretaceous rocks this flora is replaced by one which consists to a large extent of dicotyledonous angiosperms. these are found in the upper cretaceous rocks of europe and north america, and as the researches of botanists indicate their origin in circumpolar regions, their arrival in europe is an additional argument in favour of the existence of an extensive northern continent, sending a prolongation to the southward in eastern europe. the invertebrate fauna bears considerable resemblance to that of jurassic times, and many of the dominant jurassic genera are also found in cretaceous rocks. a most interesting feature is connected with the character and geographical distribution of the ammonites. in europe they are almost exclusively confined to the deposits of the northern gulf, and before their final disappearance they undergo many changes of form. we find the discoid spiral shells of earlier times, but these are accompanied by shells which are straight, curved, boat-shaped, and coiled into various helicoid spirals, sometimes having the whorls in contact, while at other times they are separate. in the chalk of britain gastropods are on the whole rare, and this fact serves to emphasize the palæontological break which occurs between the cretaceous and tertiary rocks; but when conditions were favourable, as during the deposition of some of the strata of the middle chalk, gastropods are abundant, and some are related to tertiary genera, so that we may assume that the palæontological break alluded to is exaggerated by the difference of conditions which prevailed during the deposition of the earliest tertiary and latest cretaceous sediments. in the cretaceous deposits of the southern sea, where the ammonite tribe is almost unknown, the remarkable family of the lamellibranchs known as the hippuritidæ furnish the dominant invertebrates of the period, and the representatives of this family are exceedingly scarce amongst the cretaceous strata of the northern gulf, though they are found on two or three horizons. of vertebrates, the most interesting are the reptiles. the families which predominate in jurassic times have many representatives amongst the cretaceous strata also, but the order squamata is represented by the sub-order pythonomorpha, which is characteristic of the cretaceous rocks. the best known representative is the gigantic _mosasaurus_. lastly, we have the remarkable toothed birds or odontornithes, now placed in different orders, the genus _hesperornis_ being the only representative of the sub-order odontolcæ of the ratitæ, whilst _ichthyornis_ and allied forms are placed in the sub-order odontormæ of the carinatæ. chapter xxiv. the eocene rocks. _classification._ the eocene beds of the south of england have been subdivided according to the variations in their lithological characters, and the subdivisions have received local names. the following classification is generally adopted, though the different subdivisions are by no means of equal value: upper eocene { upper bagshot beds { barton beds middle eocene bracklesham beds { lower bagshot beds { london clay[ ] lower eocene { oldhaven beds } lower london { woolwich and reading beds } tertiary strata { thanet sands } [footnote : some writers place the london clay in the middle eocene.] the deposits vary greatly when traced abroad, and the exact equivalents of the minor subdivisions of the british rocks can seldom be ascertained at any distance from england, though the division into upper, middle, and lower eocene can be made over wide areas. _description of the strata._ the character of the strata of europe and asia indicates the persistence of the northern gulf and southern ocean of cretaceous times in eocene times also, though the area of each had shrunk in the meantime, owing to the physiographical changes which occurred at the end of cretaceous times, giving rise to more extended land areas, and producing a shallow water phase over wide extents of ocean,--the final shallow water phase of the third and last great marine period of the british area. it is difficult to ascertain the exact importance of the physical break between cretaceous and eocene rocks in the south-east of england, owing to the subterranean solution of the upper part of the chalk, subsequently to the deposition of the eocene strata, but the contraction of the cretaceous gulf is shown in several ways, one of the most significant being the distribution of cretaceous and eocene rocks in the south-west of england. the existence of an outlier of cretaceous rock at buckland brewer in north devon, only three miles from the atlantic ocean, indicates the former extension westward of the upper cretaceous beds, while the occurrence of an outlier of eocene rocks at bovey tracey in south devon, resting not on cretaceous but on palæozoic rocks, shows that there was an uplift after the deposition of the cretaceous rocks and before the eocene rocks were deposited there, and that during the period of uplift the cretaceous rocks were removed. owing to these physical changes, the eocene rocks of britain are mainly mechanical sediments, some, as the oldhaven beds, being composed of coarse pebbles over a fairly wide district, while some of the earlier eocene rocks are estuarine or fluvio-marine. the eocene rocks of britain occur in four areas, namely, the london basin, the hampshire basin, the bovey tracey outlier, and the north-east of ireland and western isles of scotland. the deposits of the three southern areas may be considered together, and give general indications of an approach to land when passing westward. the lower london tertiary strata are fluvio-marine at the east end of the london basin; they become shallower water deposits when traced westward, and begin to disappear. the london clay is an estuarine deposit, which is generally supposed to have been laid down at the mouth of a large river flowing from the west. it is absent in the bovey tracey outlier. local disturbances caused the existence of a shallow water region in the east during the deposition of the middle and upper eocene deposits, and accordingly the well-marked marine deposits which form the representatives of these divisions in hampshire are replaced by the bagshot beds of the london basin, consisting chiefly of coarse mechanical sediments with a poor marine fauna, but even in the west shallow water prevailed at times during the accumulation of various plant-bearing strata. the middle eocene beds only are found in the bovey tracey outlier, though the upper eocene beds may originally have been laid down in that area, and subsequently denuded. the fourth area displays a very different succession of eocene strata, and one of extreme interest. mechanical sediments and plant-bearing clays and lignites alternate with a vast accumulation of basaltic lavas, indicating the outbreak of the volcanic forces in the british area, after a period of quiescence which lasted through the greater part of mesozoic times. the region in which these lavas were poured out was probably a land area during the greater part of the period of volcanic activity, but the horizontal lie of the lava flows and their wide extent indicate the existence of a flat tract of country, gradually raised into a plateau by the accumulation of sheet over sheet of basalt. how far this plateau extended it is impossible to say. the distribution of the lavas at the present day is somewhat limited in our isles, but there is no sign of dying out at the present margins of the accumulations, and they have probably escaped denudation in these regions, as maintained by professor judd, on account of the faults which have depressed them, while the portions which were not depressed have been removed by denudation. two views as to the origin of the lavas have been put forward: according to prof. judd, they were poured forth from gigantic volcanoes, while sir a. geikie maintains that they represent portions of massive or fissure eruptions, the molten rock having welled out from great cracks in the earth, which are now filled by once molten rock in the form of dykes. as these dykes extend far away from the present volcanic plateau, one actually extending to the yorkshire coast, we may well believe, whatever was the origin of the sheets of lava, that they were formerly spread far away from their present terminations[ ]. without entering here into a discussion of the exact nature of extrusion of these igneous sheets, it will suffice to say that all the evidence points to the formation of extensive plateaux, which must have presented a fairly uniform surface, similar to that which is still found characterising the volcanic districts of the western territories of north america. [footnote : prof. judd's views will be found in a series of papers by him on the "secondary rocks of scotland," _quart. journ. geol. soc._, vol. xxix. p. , xxx. p. , xxxiv. p. , while sir a. geikie's explanation is advanced in a paper in the _transactions of the royal society of edinburgh_, vol. xxxv.; see also the same author's _ancient volcanoes of great britain_.] the eocene rocks of the north-west of europe possess characters very similar to those of the south of england, and there are indications that the northern gulf had diminished in extent towards the east as well as towards the west. passing to southern europe, central asia and northern africa, we find the conditions of cretaceous times reproduced, and an extensive series of marine deposits extends very widely over these regions, the most persistent deposit being a mass of limestone of middle eocene age, which is almost entirely composed of the tests of nummulites, whence the development is known as the nummulitic limestone facies, and we may speak of the ocean as the nummulitic limestone sea. the incoming of shallow water conditions marked by accumulation of coarse mechanical sediments towards the end of the eocene period in some parts of the southern european area indicates the setting in, even then, of those continental conditions which culminated during the miocene period. in north america we get similar evidence of the contractions of the oceans which in mesozoic times occupied large expanses of our present continents. the climatic conditions of eocene times have been noticed in passing in chapter ix., and evidence was given to prove the prevalence of a warmer climate over the british area than that which now exists. a study of the floras of various parts of the northern hemisphere suggests that climatic zones, whose lines of demarcation ran practically parallel with the equator, existed in eocene times also, though further information upon this subject is desirable. _the eocene flora and fauna._ the flora of prevalent dicotyledonous angiosperms, which appeared in upper cretaceous times, also marks the eocene and later deposits, but a study of the floras indicates that the differentiation which now marks off the floras of different areas from one another had not occurred to so great an extent as at the present time. the existence of a rich flora in the eocene beds of circumpolar regions in the northern hemisphere should be noted, though perhaps its importance has been somewhat exaggerated. the invertebrate fauna shows an approximation to that of the present day. the remarkable ammonite fauna of mesozoic times has disappeared, and gastropods and lamellibranchs predominate, many of the forms belonging to existing genera, though very rarely to existing species. the nummulites are the most characteristic eocene fossils, and the period may be spoken of as the nummulitic period, though it is now known that nummulites are not confined to the eocene strata. the vertebrate fauna is very noteworthy. the fishes and reptiles are closely related to existing forms, and the orders of reptiles which predominated in mesozoic times have completely disappeared. but the mammals are the most interesting vertebrates of the eocene period. instead of the lowly organised forms of mesozoic times, we find representatives of many orders, including the highest, the primates. the generalised forms which serve as links between groups which are now separated to a considerable extent are of particular importance. they have been detected in eocene rocks of various regions, though the most complete series have been obtained from the eocene rocks of north america and made known to us through the numerous memoirs of professors cope and marsh[ ]. [footnote : the eocene floras of britain are described by mr j. starkie gardner and baron von ettingshausen in the _monographs of the palæontographical society_; other monographs of the same society contain an account of the eocene mollusca by mr f. e. edwards and mr s. v. wood. an idea of the generalised forms of mammalia may be obtained by perusal of that portion of nicholson and lydekker's _manual of palæontology_ in which the latter author treats of the mammalia, and in this connexion the reader will do well to read prof. huxley's "lecture on fossil horses," reprinted in his _american addresses_.] chapter xxv. the oligocene and miocene periods. (i) _the oligocene beds._ _classification._ the oligocene beds of britain are classified as follows:-- upper wanting middle hempstead beds { bembridge beds lower { osborne beds { headon beds _description of the strata._ little need be said of the deposits of this period, either in britain or abroad, except to remark that they show the further spread of continental conditions over the regions now occupied by land. the british deposits are now seen in the hampshire basin only, and have been spoken of as the fluvio-marine series, as many of the strata were laid down in continental sheets of water, while the true marine sediments are thin and infrequent. the lithological characters of deposits formed under these conditions naturally vary greatly, consisting of different kinds of mechanical sediments occasionally mixed with thin freshwater marls and limestones. on the continent similar conditions prevailed, though the occurrence of fairly wide tracts of level surface is indicated by the widespread distribution of beds of brown coal or lignite, and the coarse and thick oligocene 'nagelfluh' of switzerland points to the elevation of mountain ranges in the neighbourhood. _the flora and fauna._ the remarks made concerning the eocene flora and fauna are generally applicable to those of oligocene times, except that the oligocene fossils bear a still closer resemblance to living forms, and the nummulites are no longer dominant. (ii) _the miocene period._ beds of miocene age are wanting in britain, and on the continent they occur in isolated basins deposited in gulf-like prolongations of the ocean, never very far from land. a description of the strata and their fossil contents would be of little use for our present purposes, and the remarks made concerning the oligocene beds will apply to the miocene strata also. the period was mainly remarkable on account of the important physical changes which occurred, to which we must devote some consideration. commencing with the british area, we find in the south evidence of the separation of the london and hampshire basins at this time, for the oligocene beds of hampshire are tilted up on the south side of an anticline, which separates the hampshire basin from that of london, indicating that the movement was post-miocene, while in kent, beds of pliocene age rest on the denuded top of the chalk, showing that the elevation and denudation which accompanied it were pre-pliocene; the great wealden anticline is thus seen to be of miocene age. on the north side of the london basin the line of demarcation between eocene and mesozoic beds runs approximately parallel to the strike of the latter in that part of britain, and this points to the elevation of the mesozoic strata which gave them their present south-easterly dip about the same period, though in the absence of oligocene rocks it cannot be definitely stated that the movement was altogether post-oligocene. the present physical geography of considerable parts of britain must date from miocene times. important as the changes were in britain, they were slight as compared with those which affected europe and many parts of asia. the great mountain chains of the old world received their maximum uplift during this great period of earth-movement, and orogenic structures were impressed upon the rocks of many regions, for the tertiary mountain chains of the old world have an alpine structure impressed upon them as the result of intense lateral pressure, accordingly we find the eocene strata lifted far above their original level to heights of , feet in the alps and over , feet in the himalayas. away from these marked uplifts epeirogenic movements caused the disappearance of the seas of earlier eocene times, so that towards the close of the miocene period, the main features of the eurasian continent were much as they are now. the present drainage-systems must have originated at the same time, and the sculpture of our continent has been carried on more or less continuously by subaerial agents from miocene times to the present day. that any addition to the total area of land was made is doubtful. the land which appears to have existed to the west of britain during cretaceous and eocene times finally disappeared beneath the waters of the atlantic ocean, and the movement probably gave rise to the prominent submarine feature which now exists at some distance from the coast of ireland. a great marine period is now existent in our ocean areas, but so far as the existing continents are concerned, we are living on the fourth continental period which practically came into existence in miocene times. the strike of the uplifted strata naturally coincides on the whole with the axes of the major uplifts, and accordingly we find the mesozoic and early tertiary strata folded around axes which have a prevalent east and west direction, with others which have a trend at right angles to this. the strike of the british mesozoic rocks seems to have been determined by each of these sets of movements, so that although it is east and west in the south of england, it runs north and south in the eastern counties north of the thames. in america, although epeirogenic movements had occurred before miocene times, with the formation of wide continental tracts, these appear to have been of the nature of plains, diversified by extensive inland sheets of water, and uplift of orogenic character converted these plains into uneven tracts in miocene times. many of the movements in america, which like those of europe are still progressing with enfeebled power, differ from those of eurasia, giving rise to raised monoclinal blocks rather than to violent folds of alpine character, as seen in the western territories of north america, and as proved also by the differential movements which are now known to affect the atlantic coast of that continent. accompanying these changes in the earth's crust were others which affected the climate, at any rate locally. the warm climate of eocene times gradually gave way to a cooler climate in oligocene times, and this lowering of temperature was still further advanced in miocene times, though there is evidence that the temperature of those parts of europe which have strata representative of the miocene period was higher than it is at the present day. owing to the changes which occurred in miocene times, the area of sedimentation was extensively shifted to our present oceans, and accordingly we find that the times subsequent to those of the miocene uplifts are marked by scattered accumulations of continental character, with a few insignificant marine strata seldom found far inland from the present coast-lines. chapter xxvi. the pliocene beds. _classification._ the italian pliocene beds which have long been known have been divided into three stages, to which names have been applied which are somewhat widely used, though the division of the british deposits into the same three stages has not been made. the stages are:-- astian. plaisancean. zanclean. the classification of the british deposits may be made as follows:-- cromer "forest" series. weybourne crag and bure valley beds. chillesford crag. norwich crag and red crag. upper coralline crag. lower coralline crag. as the english deposits are somewhat scattered it is difficult to make out the exact order of succession, but the above shows the classification which is adopted by the best authorities, the norwich crag (or fluvio-marine crag as it is sometimes termed) being now supposed to represent the upper portion of the red crag. _description of the strata._ the british deposits are chiefly found in the counties of norfolk and suffolk, but isolated patches have been detected in kent and at st erth in cornwall; while the inclusion of pliocene fossils in the glacial deposits of aberdeenshire and on the west coasts and islands of great britain suggests the occurrence of pliocene beds beneath sea-level, around the british coasts, at no great distance from the land. the term 'crag' has been applied to shelly sands of which the british pliocene beds are largely composed. the oldest british pliocene strata are supposed to be the lenham beds, occurring in 'pipes' on the chalk of the north downs, which are referred to the lower coralline crag, and some writers believe that the st erth beds of cornwall are of similar age[ ]. the former are ferruginous sands, and the latter shelly sands and clays. the higher beds of the coralline crag are found in suffolk, and are largely calcareous, being made of remains of polyzoa, molluscs, and other invertebrates. they were probably deposited in deeper water than the rest of the british pliocene strata, and contain a far larger percentage of carbonate of lime. the red crag consists of ferruginous shelly sands, of the nature of sand-banks, formed near land; while the norwich crag is of a still more littoral character, and contains remains of land shells and the bones of mammalia mingled with the marine shells of the coast. the higher pliocene deposits are also coastal accumulations, even the so-called forest bed being a deposit and not a true surface soil, as proved by the observations of mr clement reid. at the summit of the cromer 'forest' series, however, is a true freshwater bed. these british deposits appear to have been laid down on a coast line which formed one side of the estuary of a large river, of which the present rhine is the 'betrunked' portion (to use a term introduced by prof. w. m. davis)[ ]. [footnote : see clement reid, _nature_, , p. ; and kendall and bell, _quart. journ. geol. soc._, vol. xlii. p. .] [footnote : see a paper by mr f. w. harmer, "on the pliocene deposits of holland, and their relationship to the english and belgian crags," _quart. journ. geol. soc._, vol. lii. p. .] on the european continent, marine pliocene beds are found in belgium and italy. the former deposits greatly resemble our crags, whilst the latter are of interest on account of the mixture of volcanic beds with marine sediments in sicily, showing that the formation of etna commenced in pliocene times. various deposits formed in inland basins are found in france and germany, but the most remarkable occur in the vienna basin, where caspian conditions prevailed over large areas, and the ordinary strata alternate with chemical deposits of which the best-known are the celebrated rock salt masses of wieliczka, near cracow. at the same time volcanic activity was rife to the south of the carpathian mountains. other deposits, which are partly referable to the pliocene period, occur in greece at pikermi, and in india in the siwalik hills; these are celebrated for their remarkable mammals, as are the pliocene strata of the western territories of north america. the occurrence of marked earth-movements since pliocene times is indicated by the nature of the deposits of barbadoes, where radiolarian cherts have furnished two echinids which are described by dr gregory as deep-sea forms. these beds were once referred to the miocene period, but there is good reason for assigning them to a later date, and correlating them with the pliocene beds of other areas, in which case there must have been a considerable uplift in this region since pliocene times, a fact of great theoretical importance. the climatic conditions of pliocene times show steady fall of temperature. the early pliocene beds of britain were deposited during the prevalence of warmer temperatures than those which now exist in the same area, but during later pliocene times, the temperature was at first similar to that now prevailing, and afterwards distinctly colder, and we find in the upper pliocene beds the remains of organisms of a northern type. in the uppermost deposit of the cromer 'forest' series, the arctic birch and arctic willow indicate the commencement of the cold which culminated in the succeeding 'great ice age.' _the flora and fauna._ little need be said of the pliocene fossils: the flora approaches that of present times, and the invertebrates are in most cases specifically identical with those now living. the vertebrates alone differ markedly from living forms, being chiefly of extinct species, and in many cases belonging to extinct genera. it is interesting to find that the mammalian fauna of pliocene times resembles the existing fauna of the area in which the beds are found, a fact long ago observed by darwin. thus the european pliocene mammals are like existing european forms, whilst in australia the mammalian terrestrial fauna consists of marsupials, and in south america there are edentata of pliocene age[ ]. [footnote : the pliocene fauna of britain is described by mr searles v. wood in the _monographs of the palæontographical society_.] chapter xxvii. the pleistocene accumulations. _classification._ the term pleistocene, as used here, is approximately equivalent to the expressions 'glacial period' and 'great ice age' of some writers; but i have adopted it in preference to these expressions, because it may eventually be possible to define the pleistocene period in such a manner as to give the term a strictly chronological meaning, whereas the other terms indicate the existence of climatic conditions which must have ceased in some areas sooner than in others. at present, climatic change gives us the best means for separating the accumulations formed subsequently to the pliocene period over large parts of the eurasian land-tract, and the most convenient division of these continental accumulations is to refer them to three periods, viz.:-- the forest period (in which we are now living). the steppe period. the glacial period. some of the accumulations which were formed during the steppe period are included in the pleistocene period by many writers, but i prefer to treat of them as post-pleistocene. in the present state of our knowledge of the glacial deposits any attempt to make a classification applicable over very wide areas is doomed to failure, and the very principles upon which the classification should be based are a subject of disagreement. the most promising basis for classification is founded on alternate recession and advance of land-ice, though the proofs that advance takes place simultaneously over very wide areas are not yet forthcoming. dr j. geikie in the last edition of his work _the great ice age_ adopts four periods of glaciation, with intervening periods of recession, and this division accords with the observations of many foreign geologists. in order to understand the method of classification upon this basis, a few words concerning glacial deposits in general will not be out of place. glacial accumulations may be divided into three classes:--(i) true glacial accumulations, formed on, in, and under the ice, and left behind upon its recession, (ii) marine glacial deposits, laid down in the sea, when floating ice is extensively found on its surface, and (iii) fluvio-glacial deposits, laid down by streams which come from the ice. the two former indicate glacial conditions, while the occurrence of fluvio-glacial deposits overlain by true glacial deposits indicates an advance of land-ice, for the fluvio-glacial deposits are accumulated in front of those which are truly glacial. accordingly if we find alternations of glacial and fluvio-glacial deposits on a large scale, we may fairly infer the alternation of periods of great glaciation with others when the ice diminished, or in other words of glacial and interglacial periods. there is, however, in many cases great difficulty in distinguishing glacial deposits from marine glacial ones, while some of the true glacial deposits formed _in_ the ice (englacial deposits) cannot readily be distinguished from those of fluvio-glacial origin. furthermore, as the terminal moraines of land-ice often rest upon other true glacial deposits, it is often difficult to know whether we are dealing with the products of one or two glaciations over limited areas. the test of superposition is often applicable, and one is enabled to obtain some clue as to the relative order of events. in england at least three periods of glaciation seem to be indicated by the glacial deposits. on the east coast the cromer forest series is succeeded by the cromer till, and in yorkshire the basement clay occupies a similar position with regard to the overlying glacial accumulations to that of the cromer till. whether these deposits be marine or terrestrial, and the evidence is not yet sufficient to settle this question to the satisfaction of all geologists, there is no doubt that they are glacial. above them, in east anglia, lies the contorted drift, the origin of which is still a moot point, and it is overlain by the great chalky boulder clay, which extends far and wide over east anglia, the midland counties and into yorkshire. evidence has been adduced to connect this with the _till_ or boulder clay which spreads over the upland districts of the north of england at the foot of the main hill-systems. this set of deposits indicates a second glaciation. as the upland till is often ploughed out by glaciers which have left their traces in the form of moraines in our upland regions, we seem here to have evidence of a third glaciation, which naturally leaves no traces in the southern districts, and the exact age of this cannot be ascertained in the absence of fossil evidence, though we may provisionally refer it to the pleistocene period. another attempt has been made to classify the glacial deposits, on the supposition that there have been periods of elevation and depression of the land during pleistocene times. some writers advocate one interglacial period when the land was depressed to an extent of and perhaps feet, while others have advocated the occurrence of a number of such interglacial marine periods. the evidence for the supposed oscillations is furnished by the existence of shell-bearing sands associated with boulder clays at high levels, the best known being on moel tryfan in caernarvonshire, near macclesfield in cheshire, and near oswestry in shropshire. as many geologists believe that these shells have been carried to their present position by ice in a way which it is not our province to discuss here, we may dismiss this method of classification as based upon events which cannot be proved to have occurred. in the present state of our knowledge, it is indeed best to avoid, as far as possible, classifications which are intended to be applicable over wide regions, and to devote our attention to local details, gradually piecing together the evidence which is obtained as the result of exhaustive examination of each separate area[ ]. [footnote : the glacial literature of our own island only, is so extensive that the student may well be bewildered when he attempts to grapple with it. he is recommended to read the following general works: j. geikie, _the great ice age_. rd edition, . h. carvill lewis, _the glacial geology of great britain and ireland_. . g. f. wright, _man and the glacial period_, , and _the ice age in north america_, . sir c. lyell, _antiquity of man_. th edition, . for the glacial geology of special regions the following papers may be consulted: _the lake district and adjoining neighbourhood._ e. h. tiddeman, "evidence for the ice sheet in north lancashire &c." _quart. journ. geol. soc._, vol. xxviii. p. . j. g. goodchild, "glacial phenomena of the eden valley &c." _quart. journ. geol. soc._, vol. xxxi. p. , and j. c. ward, _mem. geol. survey_, "the geology of the northern half of the lake district." _yorkshire._ g. w. lamplugh, "drift of flamborough head," _quart. journ. geol. soc._, vol. xlvii. p. . _lincolnshire._ a. j. jukes-browne, _quart. journ. geol. soc._, vol. xxxv. p. and xli. p. . _east anglia._ clement reid, _mem. geol. survey_, "the geology of the district around cromer." _north wales._ t. mck. hughes, "drifts of the yale of clwyd" &c. _quart. journ. geol. soc._, vol. xliii. p. , and a. strahan, "glaciation of south lancashire, cheshire, and the welsh border," _ibid._, vol. xlii. p. . _switzerland._ c. s. du riche preller, "on fluvio-glacial and interglacial deposits in switzerland," _quart. journ. geol. soc._, vol. li. p. and "on glacial deposits, preglacial valleys and interglacial lake formations in sub-alpine switzerland," _ibid._, vol. lii. p. . the reader will find references to other works on the glacial geology of other districts by consulting the general works referred to on the preceding page.] the foregoing remarks will convince the student that any attempt to show the distribution of land and sea during any part of the glacial period is not likely to meet with general acceptance, as so much depends upon the terrestrial or marine origin of the deposits of the lowlands, and the mode of formation of the shell-bearing drifts of high levels. the occurrence of elevation to a greater height than that which our country at present possesses during portions at any rate of the glacial period has been inferred on general grounds, but direct evidence in favour of it is furnished by the existence of a number of ancient valleys on the land around our coasts, whose floors are often considerably below sea-level, while the valleys are now completely filled up with glacial accumulations, except where they have been partially re-excavated by streams which for some distance run above the courses of the ancient streams. the climatic conditions of glacial times can only be briefly touched upon in this place. if the periods of advance can be proved to be contemporaneous over wide areas, this points to alternations of colder and warmer periods, or at any rate of drier and wetter periods, though local advance may be due to a number of causes. it must be borne in mind that with the temperature remaining the same, advance of ice can be brought about by increased precipitation of aqueous vapour in the form of snow. the question of the cause of the glacial period is one that only indirectly affects the stratigraphical geologist until he has accumulated sufficient evidence to indicate the cause. it must suffice to observe that the extremely plausible hypothesis of croll (for which the student should consult dr croll's _climate and time_) does not explain the apparent gradual lowering of climate throughout tertiary times till the cold culminated in the pleistocene period, and the student will do well to remain in suspense concerning the cause of the ice age until further evidence has been brought to bear upon it. _the glacial flora and fauna._ the glacial deposits naturally yield few traces of life, except those which have been derived from other deposits, and we are dependent for our information concerning the fauna and flora of the glacial period upon the remains furnished by the interglacial deposits. unfortunately it is very hard to ascertain which deposits are interglacial, and many which have been claimed as such are either preglacial or postglacial. the meagre evidence which we possess points to the existence of an arctic fauna or flora in britain during the prevalence of this glacial period. a question which has received much attention of recent years is that of the existence of preglacial or interglacial man, on which much has been written. the existence of man in glacial times is probable, but it is the opinion of many of those who are most competent to form a judgment, that it has not been proved in the only conclusive way, namely, by the discovery of relics of man in deposits which are directly overlain by glacial deposits, or which at any rate are demonstrably older than glacial deposits[ ]. [footnote : on the question of preglacial and interglacial man, see w. boyd dawkins, _early man in britain_; h. hicks, _quart. journ. geol. soc._, vol. xlii. p. , xliv. p. , and xlviii. p. ; t. mck. hughes, _ibid._, vol. xliii. p. ; sir j. evans, _presidential address to british assoc._ .] chapter xxviii. the steppe period. the occurrence of a period marked by dry climate over wide areas of the eurasian continent, and possibly also in north america, is evidenced by the widespread distribution of an accumulation known as _loess_, concerning the origin of which there has been much difference of opinion, though that it was formed subsequently to the glacial period seems to be generally admitted, inasmuch as it is largely composed of rearranged glacial mud. the formation of the loess as a steppe-deposit was first advocated by baron von richthofen, and his views were supported by nehring after study of the loess-fauna. richthofen's explanation of the loess as due to the spread of dust by wind in a dry region is becoming widely accepted, and it necessitates the widespread occurrence of steppe conditions, as the loess has a very extensive geographical range, and may be truly regarded as the normal continental deposit of eurasia during the period immediately succeeding the glacial period. in our own country, as the sea cannot have been far distant during these times the normal loess is not found, but several accumulations occur, which on stratigraphical and palæontological grounds must be regarded as synchronous with the formation of the loess. these are certain rubble-drifts of the southern counties, the older river-gravels of southern england, and some of the older cave deposits of various parts of england. it is doubtful whether any classification into minute subdivisions can be adopted for them, though prof. boyd dawkins has advocated their separation into an older age of river drift man, and a newer period of cave man, on account of the evidences of a lower state of civilisation afforded by examination of the river drift implements when compared with those fashioned by cave man. roughly speaking, the steppe period corresponds with the period during which palæolithic man existed, at any rate in north-west europe, and we may speak of the steppe period as the palæolithic period, without asserting that palæolithic man necessarily disappeared at the time when the climate changed and caused the replacement of steppe conditions by others favourable to forest-growth. _description of the accumulations._ the loess consists of unstratified calcareous mud or dust, with a peculiar vertical fracture, and is interesting rather on account of the nature of its fossils and of its distribution than for its lithological characters. as it is not found in britain it is not necessary to say much about it, but merely to refer to the published descriptions[ ]. [footnote : an account of richthofen's views by that author will be found in the _geological magazine_, dec. , vol. ix. ( ), p. , and the fauna of the loess is described by nehring (_ibid._, p. ).] the british deposits require some notice, as their characters and mode of occurrence are of some significance. along the south coast are deposits of coarse rubble which have yielded some organic remains, which have been described by mr clement reid[ ], who also discusses their origin. the rock, also known as the elephant bed, consists of angular fragments of flint and chalk, and seems to have been produced by streams which were able to flow over the surface of the chalk when it was frozen. many other similar deposits in the south of england, which are found on the open surface, may have had a similar origin. [footnote : c. reid, "origin of dry chalk valleys and of coombe rock," _quart. journ. geol. soc._, vol. xliii. p. .] the palæolithic river-gravels are found at various distances above present river-levels, and are the surviving relics of alluvial deposits which were laid down when the rivers ran at a higher level than they now do. that they are newer than the main glacial drifts of the region in which they occur is indicated by the frequent presence in them of boulders derived from the drift. their antiquity is shown by the physical changes which have occurred since their deposition (there having been sufficient time since then to allow of the excavation of some river-valleys to a depth of over one hundred feet beneath their former level), and also by the character of the included mammals which will presently be referred to. the deposits vary in coarseness, like those of modern alluvial flats, from the coarse gravels of the river-beds to the fine loams and marls of the flood-plains. they are found, in britain, with their typical mammalian remains, south-east of a line drawn from the mouth of the tees to the bristol channel. the cave-deposits have a wider distribution than those which have just been noticed, being also found to the north-west of the above-mentioned line in yorkshire, and in north and south wales. in the south of england they are found as far east as ightham in kent, and in a westerly direction to torquay and tenby. the ightham deposits occur in fissures and consist of materials which were apparently introduced from above by river action[ ]. the cave-deposits of limestone areas are sometimes found in fissures, but at other times in caverns with a fairly horizontal floor, on which the various accumulations lie in order of formation. the deposits vary in character and may be divided into three groups, though accumulations of intermediate character are found; the first group consists of cave-earths and cave-breccias--formed by weathering of the limestone, and the retention of the insoluble residue, as a more or less ferruginous mud, mixed with angular fragments of limestone, and with the remains of creatures which inhabited the caves; the second group consists of true deposits laid down under water, as gravels, sands, and laminated clays; while the third is composed of limestone deposited from solution in water, in the form of stalagmite[ ]. [footnote : the ightham fissures and their contents are described by messrs abbot and newton, _quart. journ. geol. soc._, vol. l. pp. and .] [footnote : the reader should consult prof. w. boyd dawkins' works on _cave hunting_ and _early man in britain_, for information concerning the cave deposits. see also sir c. lyell, _antiquity of man_; sir j. evans, _ancient stone implements of great britain_, and sir j. lubbock, _prehistoric times_. in these works references will be found to papers by messrs pengelly, magens mello, tiddeman and others on the caves of devon, derbyshire and yorkshire. references have already been made to papers upon the caverns of north wales.] the organic contents of the palæolithic period are of much interest, and it is desirable to discuss their character before making further observations upon the physical conditions of the period. _the palæolithic flora and fauna._ the plants of some of the earlier deposits of the age we are considering show the prevalence of cold conditions during their accumulation, for instance the arctic birch and arctic willow are found in the accumulations beneath the implement-bearing palæolithic deposits of hoxne in suffolk[ ]. the invertebrate fauna consists essentially of the remains of molluscs. the loess molluscs are chiefly pulmoniferous gastropods which lived upon the land, though swamp forms are occasionally associated with them. the palæolithic river-gravels have yielded numerous land- and freshwater-molluscs of living species, though some which are abundant in the british gravels are now extinct in britain, e.g. _cyrena (cobicula) fluminalis_ and _unio littoralis_. marine deposits of this age are occasionally found, as at march, in cambridgeshire, where the fauna closely resembles that of our present sea-shores. [footnote : these beds are described by messrs reid and ridley, _geol. mag._ dec. iii. vol. v. p. . see also c. reid on the "history of the recent flora of britain," _annals of botany_, vol. ii. no. , aug. .] the vertebrate remains are much more remarkable, and it is not quite clear that the association of forms whose living allies now live under widely different conditions has been satisfactorily explained. the river-gravels and cave-deposits contain remains of temperate forms, as the bison, and brown bear, associated with those of northern forms, as the mammoth, woolly rhinoceros, glutton, reindeer, and musk ox, and also with those whose living allies are inhabitants of warmer regions, like the lion, hyæna, and hippopotamus. one of the most remarkable creatures is the sabre-toothed lion or _machairodus_, remains of which have been discovered in kent's cavern, torquay, and in the caves of cresswell crags, derbyshire. the loess fauna consists of characteristic steppe animals, such as the jerboa, saiga antelope and steppe-porcupine, and it is interesting to find an indication of this fauna in the ightham fissures. the first undoubted relics of mankind are found in the palæolithic deposits, which are very widely spread over the eurasian continent. they consist mainly of implements of bone and stone, the latter being chipped, but never ground or polished, though both bone and stone implements are frequently ornamented with engraved figures. the cave-deposits have furnished implements of a higher type than those usually found in the river-drifts, but the latter are also found in caverns in deposits beneath those containing the higher type, hence the division of the period into two minor periods, that of river-drift man, and that of cave-man[ ]. [footnote : concerning this matter, the reader should consult prof. boyd dawkins' _early man in britain_. sir j. prestwich has argued in favour of the existence of a group of implements found on the plateau south of the thames of an age antecedent to that of the ordinary river-drift implements. see _quart. journ. geol. soc._, vol. xlv. p. .] there are several questions of interest connected with the palæolithic fauna, three of which deserve some notice here. the absence of the relics of the palæolithic mammalia and of the human implements in the river-gravels north-west of the line drawn between the tees and bristol channel, and the presence of the mammalian remains in the caverns of that area requires some explanation. one such explanation assumes that the relics were destroyed in the open country to the north-west of that line, owing to glaciation, but it is not by any means universally accepted. another difficulty which in the opinion of some writers has not been fully cleared up is the mixture of apparently southern forms like the hippopotamus, with others of northern character like the musk ox, under such conditions as to show that the creatures lived in the british area contemporaneously. seasonal migration might account for it, but the wide belt of overlap of apparent northern and southern forms requires something more, though secular changes of climate might shift the belt of seasonal overlap from one place to another, causing the entire belt of overlap to extend over a considerable distance. the third, and perhaps most important difficulty is the abrupt change from the palæolithic type of implement to the neolithic type, characteristic of the next period. some implements, as those of the kitchen-middens of denmark, and those found at brandon and cissbury in this country, have been appealed to as intermediate in character, but evidence has been brought forward to show that each set is truly neolithic, the one being the implements of the lowly fisher-folk who lived contemporaneously with the makers of the highly finished polished implements of denmark, while the others are unfinished implements thrown away during the manufacture on account of flaws or accidental fractures. the difficulty is increased when we take into account the great physical and faunistic changes which occurred between palæolithic and neolithic times. the country was undoubtedly more elevated than it is at present during portions if not during the whole of palæolithic times, as shown by the appearance of the great mammals in britain, the discovery of their remains beneath sea-level, and especially the occurrence of remains in the caverns of rocky islands such as those of the bristol channel, where they could not possibly have existed unless the present islands were connected with the mainland. the fossils of the times between the glacial period and the neolithic period indicate variations of climatic conditions. upon this point i cannot do better than quote the words of sir john evans in his presidential address to the british association at toronto[ ]. "at hoxne the interval between the deposit of the boulder clay and of the implement-bearing beds is distinctly proved to have witnessed at least two noteworthy changes in climate. the beds immediately reposing on the clay are characterised by the presence of alder in abundance, of hazel, and yew, as well as by that of numerous flowering plants indicative of a temperate climate very different from that under which the boulder clay itself was formed. above these beds characterised by temperate plants, comes a thick and more recent series of strata, in which leaves of the dwarf arctic willow and birch abound, and which were in all probability deposited under conditions like those of the cold regions of siberia and north america. "at a higher level, and of more recent date than these--from which they are entirely distinct--are the beds containing the palæolithic implements, formed in all probability under conditions not essentially different from those of the present day." [footnote : _report brit. assoc._ for , p. .] chapter xxix. the forest period. subsequently to palæolithic times, the physical conditions over eurasia changed greatly, and at the commencement of neolithic times the conditions were favourable for the growth of forests over wide regions of that continent. at the commencement of the forest period the physical conditions were very much the same as they are at present, though minor changes have of course taken place since then, including probably a submergence of large parts of britain to a depth of about fifty feet beneath its former level, as indicated by the existence of neolithic submerged forests round many parts of our coast-lines. the forest period may be best subdivided for local purposes by reference to the civilisation of mankind at different times, and in this way we obtain the following divisions: historic iron age. prehistoric iron age. bronze age. neolithic age. a classification may also be based upon changes in the flora. in denmark the peat deposits of this age are divisible into five layers, characterised by different dominant forms of trees. these are as follows in descending order: fifth layer: beech ... iron age fourth layer: alder third layer: oak ... bronze age second layer: scotch firs ... neolithic age lowest layer: poplar. in our own country the forest growth has been much interfered with by man, but the lower fenland peat gives a good example of the material formed by forest growth. it is not necessary to touch on the various accumulations which are now being formed in different parts of our island, except to remark that the deposits of the forest period give indications of earth-movements on a small scale, which is well seen in the fenland, where the forest peat is covered in places by a "buttery clay" with _scrobicularia piperata_ indicating submergence, and above this is a marsh peat. the flora and fauna of the forest period are practically those of the present day, though the larger forms of mammalia have disappeared one by one. the irish elk and _bos primogenius_ probably became extinct early in the period, while as far as britain is concerned the wolf, bear, and beaver have disappeared within historic times. the relics of man deserve passing notice. the neolithic period is characterised by the absence of metal instruments, though those made of stone were much more highly finished than those of palæolithic times, and were often ground and polished. the first metal which was largely worked was bronze, which gradually replaced stone, though stone was extensively used in the bronze age, as indicated by the imitation of bronze implements in stone. the bronze age in turn was replaced by the prehistoric iron age; at first, when iron was scarce, bronze implements were merely tipped with iron, but ultimately the one metal was practically replaced by the other. the date of the palæolithic period is unknown; no approximate date can be satisfactorily assigned to it, but various calculations, founded on different data, have been made as to the age of the neolithic period, and several of them agree in placing it at about years from the present time. it will be seen that no sudden and violent change marks the incoming of the human race, which to the geologist is but one of a large number of events which have followed each other in unbroken sequence, and accordingly the thread of the story where abandoned by the geologist is taken up by the antiquary, and passed on by him to the historian[ ]. [footnote : the student may obtain information concerning the neolithic age in britain in boyd dawkins's _early man in britain_; sir j. evans' _early stone implements of great britain_, and sir j. lubbock's _prehistoric times_. in the latter work he will find a good account of the neolithic remains of denmark and of the swiss lake dwellings. for information concerning the bronze age he should consult evans' _ancient bronze implements of great britain_. the varied danish antiquities of neolithic and bronze ages are figured in h. p. madsen's _antiquités préhistoriques du danemark_. the prehistoric fauna of the fenlands is described in sir r. owen's _history of british fossil mammals and birds_.] chapter xxx. remarks on various questions. there are many problems connected with geology which can only be solved by detailed study of the stratified rocks, and when solved the principles of the science will be more fully elucidated. in the present state of our knowledge some of these problems are ripe for discussion, others can merely be indicated, while others again have probably remained hidden, though it will be the task of the geologist of the future to clear them up. among the many questions which demand knowledge of stratigraphical geology for their right understanding are the following, which will be briefly considered in this chapter:--the changes in the position of land and sea in past times, and the growth of continents; the replacement of a school of uniformitarianism by one of evolutionism; and the duration of geological time. _changes in the position of land and sea._ certain physicists have arrived at the conclusion that the general position of our oceans and continents was determined at a very early period in the earth's history, and that the changes which have occurred in their position since then have been comparatively insignificant. the wide extent of land over which stratified rocks are distributed at once indicates that from the point of view of the geologist the changes have been very important, and it is worth inquiring whether they are not sufficiently important to prove that the primitive oceans and continents have undergone so much alteration as to be unrecognisable. some authorities, while recognising the great changes which have occurred in the relative position of land and sea during those periods of which geologists have direct information, suppose that the changes took place to a large degree in certain 'critical areas' bordering the more stable areas of permanent ocean on the one side and permanent land on the other. in discussing the question of general permanence of land and ocean regions it will be convenient to commence with a study of the present land areas, and at the outset we may take into consideration the present distribution of marine sediment over different parts of the land, using the last edition of m. jules marcou's geological map of the world for the purpose[ ]. a glimpse at this map indicates that more than half of the land areas are occupied by rocks which are as yet unknown (many of which _may_ be marine sediments), or by crystalline schists of which the mode of origin has not yet been fully explained, so that a large part of central asia, the interior of africa, and of south america may have existed as land from very early times, and the same may be said of smaller portions of europe and north america. actual observation of a geological map therefore indicates the possibility that about half of the land surfaces may have existed as such through very long periods, but though there is a possibility of this, the probability is not very great. the unknown regions, as remarked above, may consist to a considerable extent of marine sediments, and the existence of isolated patches of late palæozoic and of mesozoic strata in the heart of central asia, points to the submergence of much wider regions than those in which these isolated patches have been found. again, the character of the sediments when they abut against the crystalline schists frequently proves that these sediments once extended further over the crystalline schists, and have since been removed by denudation, so that even if we assume that the crystalline schists are all of very early date, and not necessarily formed in any case from marine sediments, we cannot suppose that all the area occupied by them has existed as land for long periods of time. on the other hand, the major part of europe and north africa, extensive tracts in asia, the greater part of australia, a very large part of north america and considerable tracts of south america give proofs of having been occupied by the oceans in palæozoic and later times. [footnote : a reduced copy of this map will be found opposite the title-page of the first volume of prof. prestwich's _geology_.] it may be answered that most of these regions containing marine sediments occur in critical areas, which have undergone a certain amount of oscillation owing to earth-movements, and that the interior parts of the great continental masses have been practically stationary. but if these lands had been land-areas through geological ages they must have been acted upon by the agents of subaerial denudation, throughout these ages, and long ago reduced to peneplains[ ] unless the action of these subaerial agents was counteracted by that of elevating forces, but if these forces were sufficient to counteract the action of subaerial denudation through countless ages, they were also sufficient to raise extensive tracts of land above sea-level, and materially to alter the distribution of land and sea, and if elevation could go on to this extent, why not also depression? [footnote : a term proposed by prof. w. m. davis for a nearly level surface of subaerial denudation, as opposed to a plain of marine denudation.] proceeding a step further, and examining the character of the sediments as well as their geographical distribution, we find further evidence of great crust-movements. it has been urged that deep-water sediments do not occur amongst the strata found on the continents,--that there are no representatives of the abysmal deposits of recent ocean floors amongst the strata of the geological column[ ], but the researches of the last two decades have brought to light foraminiferal and radiolarian deposits, pteropodal deposits, and possibly deep-sea clays, which are comparable with those in process of formation at great depths in existing oceans, and though the proofs of their deep-sea origin are not always as full as might be desired in the case of the older rocks[ ], we can speak with greater certainty when we examine those of tertiary age, and if the deep-sea accumulations of this late date can be uplifted above sea-level, this is much more likely to have occurred with those of past times. when a deposit like the radiolarian rock of barbadoes, the deep-water character of which has been conclusively proved, can be elevated into land since miocene or possibly pliocene times, it is evident that the crust-movements have been sufficient to produce the most profound changes in the distribution of land and sea during the long ages which are known to us. another argument against the occurrence of extensive changes has been derived from an examination of those islands which are spoken of as oceanic islands. strictly speaking an oceanic island is one in which the present fauna and flora give indications of their introduction by transport across intervening sea, and no indications of the existence of forms of life which inhabited it when it was once united to a continent; it may be inferred with a considerable degree of certainty that these islands have been isolated for long periods of time. it has been stated that these oceanic islands never contain marine sediments of any considerable degree of antiquity, and that there are therefore no traces of former continents over those wide tracts of ocean which are occupied by oceanic islands. the evidence is of a negative character. the islands would be less likely to exhibit ancient sediments than continents, for being near the ocean, they would be readily submerged, and the older deposits masked by newer ones, though this need not necessarily account for the entire absence of ancient rocks amongst them. the danger of the argument lies in the fact that we do not yet know how far these old rocks really are absent, as the geology of the oceanic isles has not been fully explored from this point of view, and already several cases of the asserted presence of ancient rocks on these islands have been recorded. [footnote : see mr a. r. wallace's _island life_.] [footnote : see chapter ix.] the argument derived from the present distribution of organisms is far too complex to be discussed here, and the student is recommended to read a masterly review of the evidence in dr w. t. blanford's presidential address to the geological society in , on the question of the permanence of ocean basins[ ]. after reviewing the evidence furnished by a study of modern distribution he concludes that it "is far too contradictory to be received as proof of the permanence of oceans and continents." [footnote : _quart. journ. geol. soc._, vol. xlvi., _proc._, p. .] the existence of former extensive land tracts over regions now occupied by sea is naturally more difficult to prove than that of sea over land, as we depend upon inference rather than actual observation to a much greater degree than when considering the permanence of continents, nevertheless a considerable amount of indirect evidence in favour of the existence of widespread land tracts over our present ocean regions has been accumulated and will be briefly noticed. we may take first the evidence derived from the nature of sediments, and afterwards that which has been acquired by studying distribution of organisms in past times. the indications of existence of an extensive tract of continent over the north atlantic ocean, during palæozoic times have already been considered, and it was seen that the thinning out of the palæozoic sediments when traced away from the present atlantic borders in an easterly direction over europe and in a westerly one over north america pointed to the existence of this palæozoic 'atlantis,' as maintained by prof. hull in his work, "contributions to the physical history of the british isles." this writer gives some reasons for supposing that the continental mass began to break up towards the end of palæozoic times, though it is not clear that complete replacement of land by sea occurred, and the nature of the wealden deposits has been pointed to as evidence of the existence of an extensive tract of land to the west of britain during the cretaceous period. the palæontological evidence in favour of destruction of ancient continental areas and their replacement by the sea is more satisfactory than that which is based on physical grounds. the distribution of the glossopteris flora of the permo-carboniferous period points to the former existence of a great southern continent, including the sites of australia, india, south africa and south america,--the gondwanaland of prof. e. suess[ ]. [footnote : on this question and that of the other destroyed continental areas noted here, see w. t. blanford's _presidential address_, _loc. cit._] again, a study of jurassic and cretaceous faunas has led palæontologists to conclude that there was a connexion betwixt s. africa and india in mesozoic times across a portion of the area now occupied by the indian ocean, and also between s. africa and s. america, and these inferences are supported by study of the distribution of existing forms. the sudden appearance of the dicotyledonous angiosperms in upper cretaceous rocks has also been used as evidence of destruction of considerable tracts of land subsequently to upper cretaceous times, and there is a certain amount of evidence in favour of the existence of this land in the north polar region, in an area now largely occupied by water, though relics of it are left, as the faroe isles, spitsbergen, novaya zembla and franz josef land. i cannot conclude the consideration of the question of permanence of oceans and continents more fitly than by quoting from dr blanford's address. he says, "there is no evidence whatever in favour of the extreme view accepted by some physicists and geologists that every ocean-bed now more than fathoms deep has always been ocean, and that no part of the continental area has ever been beneath the deep sea. not only is there clear proof that some land-areas lying within continental limits have at a comparatively recent date been submerged over fathoms, whilst sea-bottoms now over fathoms deep must have been land in part of the tertiary era, but there are a mass of facts both geological and biological in favour of land-connexion having formerly existed in certain cases across what are now broad and deep ocean[ ]." [footnote : _loc. cit._, _proc._ p. .] _growth of continents._ whatever view as to the general permanence of continents and oceans be ultimately established, the occurrence of widespread changes in the position of land and sea is indisputable, and it is of interest for us to consider the nature of these changes in the formation of continents. prof. j. d. dana has put forward a hypothesis of growth of continents by a process of accretion, causing diminution in the oceanic areas, which at the same time became deeper: such growth need not always take place in exactly the same way, and study of the distribution of the strata of the north american continent suggests that the growth there was endogenous, the older rocks lying to the west and north forming a horseshoe shaped continent enclosing a gulf-like prolongation of the atlantic, which became contracted by deposition and uplift in successive geological periods, though it is still partly existent as the gulf of mexico. the eurasian continent, especially its western portion, suggests more irregular growth around scattered nuclei of older rocks, though the process is not completed, and many gulf-like prolongations, as the baltic and the mediterranean, still remain as water-tracts, which have not yet been added to the continents. although extensive additions to continents may be and no doubt are often largely due to epeirogenic movements, the influence of orogenic movements on continent-formation is very pronounced. as the result of orogenic movements, the rocks of portions of the earth's crust become greatly compressed, and give rise to masses which readily resist denudation; moreover, these comparatively rigid masses, as shown by m. bertrand, tend to undergo elevation along the same lines as those which formed the axes of previous elevations, and accordingly after a continental area has undergone denudation for a considerable period, the uplands consist of rocks which have undergone orogenic disturbance, while the tracts of ground which are occupied by rocks which have not suffered disturbances of this character, even if originally uplifted far above sea-level, tend to be destroyed, and ultimately occupied by tracts of ocean. stumps of former mountain chains may be again and again established as nuclei of continents and as every period of orogenic movement will add to the number of these nuclei, the continental areas must in course of time become more complex in structure. moreover, as some areas are affected by orogenic movements to a greater extent than others, the complexity of different continental masses will vary. thus, western europe has been affected by orogenic movements during many periods since the commencement of cambrian times and its structure is extremely complex, while the central and western parts of russia have not been subjected to violent orogenic disturbances since cambrian times, and accordingly we find the structure of that area comparatively simple; the greater part of africa seems to have escaped these movements since remote times, and the structure of that continent is extremely simple when compared with the eurasian continental tract. it need hardly be stated that the formation of extensive chains composed of volcanic material, by accumulation of lavas and ashes on the earth's surface, may give and often has given rise to more rigid tracts, which will bring about the same effects as those produced by orogenic disturbance as illustrated on a small scale by the lower palæozoic volcanic rocks of cambria and cumbria. _uniformitarianism and evolution._ according to the extreme uniformitarian views held by some geologists, the agents which are in operation at the present day are similar in kind and in intensity to those which were at work in past times, though no geologist will be found who is sufficiently bold to assert that this holds true for all periods of the earth's history, but only for those of which the geologist has direct information derived from a study of the rocks, and he is content to follow his master hutton in ignoring periods of which he cannot find records amongst the rocks. the modern geologist, however, while rightly regarding the rocks as his principal source of information finds that he cannot afford to ignore the evidence furnished by the physicist, chemist, astronomer and biologist, which throws light upon the history of periods far earlier than those of which he has any records preserved amongst the outer portions of the earth itself, just as the modern historian is not content with written records, but must turn to the 'prehistoric' archæologist and geologist for information concerning the history of early man upon the earth. interpreting the scope of geology in this general way, rigid uniformitarianism must be abandoned. assuming that the tenets of the evolutionist school are generally true, the question is, how far does this affect the geologist in his study of those periods of which we have definite records amongst the rocks? this is a question which cannot readily be answered at the present day, for our study of the rocks is not sufficiently far advanced to enable us to point out effects amongst the older rocks which were clearly caused by agents working with greater intensity than they do at present, but as, on the other hand, we cannot prove that these effects are due to agents working with no greater intensity than that which now marks these operations, it is unphilosophical to assume the latter. no student of science at the present day would state that because there has been no observed case of incoming of fresh species within the time that man has actually observed the present faunas and floras, the hypothesis of evolution of organisms is disproved, for the time of observation has been too short, and similarly the time which has elapsed since the formation of, say, the cambrian rocks may have been too short, as compared with the time which has elapsed since the formation of the earth, to allow of any important change in the operation of the geological agents. leaving out of account, for the moment, the actual evidence which has been derived from a study of the rocks, we may briefly consider the theoretical grounds upon which the substitution of an evolutionist school of geology for one of uniformity has been suggested[ ]. the principal sources of energy which have exerted an influence upon geological changes are the heat received from the sun and that given off from the earth itself, both of which must have diminished in quantity throughout geological ages. to the former source we largely owe climatic changes and the operations of denudation, and accordingly of deposition; to the latter, those of earth-movement and vulcanicity. it by no means follows that because the agents were once potentially more powerful than now, they would necessarily produce greater effects, for that depends to some extent upon the various conditions which prevailed at different times. to give an example:--if there had at any time been a universal ocean of considerable depth, however active the agents of denudation were then, they could produce no effect whatever, having nothing to work upon; to take a less extreme case, if our continents at any past time were smaller and less elevated than at present, agents of denudation working with greater intensity than that of the present agents need not necessarily have produced a greater amount of denudation than that which is going on at the present day. again, let us consider vulcanicity: "it is as certain," says lord kelvin, "that there is less volcanic energy in the whole earth than there was a thousand years ago, as it is that there is less gunpowder in a 'monitor' after she has been seen to discharge shot and shell, whether at a nearly equable rate or not, for five hours without receiving fresh supplies than there was at the beginning of the action." but it does not follow that the manifestations of volcanic activity were necessarily more violent in early geological times than now, for the degree of violence would be affected by other things than the volcanic energy, such as the thickness of the earth's crust. [footnote : the student may consult an interesting article by prof. sollas bearing on this subject. see _geol. mag._ dec. , vol. iv. p. .] and now, let us consider briefly the characters of the rocks of the crust, to see if they throw any light upon this question. the earliest sediments of which we have any certain knowledge resemble in a striking manner those formed at the present day, and they seem to have been formed under very much the same conditions, though further work may show that there were somewhat different conditions which did produce definite differences in the characters of the earlier strata[ ]. our knowledge of earth-movement and vulcanicity which took place in past times is still too small to enable us to draw any certain conclusions connected with the subject under discussion from it. perhaps the most suggestive indication of one set of conditions having been generally similar in those early periods of which we have definite records amongst the rocks is furnished by study of past climate. if we accept the nebular hypothesis as a starting point, we must admit that in the early stages of the earth's history the temperature of the surface, which would then be largely dependent upon the amount of heat given out from the earth itself as well as upon that received from the sun, must have been much higher than it is at the present day, and indeed the mere diminution of the amount of heat received from the sun would probably be sufficient to account for a very marked lowering of the temperature. besides this change of temperature, resulting in gradual lowering of temperature over the whole earth's surface, we have other changes dependent upon different conditions, as proved by the fact, that there have been alternations of glacial and genial periods. if the general temperature had been very high in the early periods of which we have actual records, the oscillations would not be sufficient to produce a lowering of temperature sufficient to cause glacial periods, whereas if it had not been appreciably higher than now, glacial periods might be produced. this may be represented diagrammatically. [footnote : on this matter see teall, j. j. h., 'presidential address to section c,' _report of the british association_, .] let _a_ represent the temperature at the commencement of earth-history and _b_ that necessary for glaciation, and _bc_ the lapse of time between then and now. the curved line indicates the gradual fall in temperature due to diminution of the amount of heat, while the zigzag line represents the oscillations due to secular climatic changes. if the cambrian period x occurred comparatively soon after the commencement of earth-history as shown in fig. _a_, no glaciation could be produced, even during periods when secular changes caused colder conditions than the mean, whereas if the cambrian period occurred at a time very remote from the commencement of earth-history as shown in _b_, glacial conditions could be produced then as now, for the mean temperature, as shown by the distance of the curve from the line _bc_, would be practically as it now is. the studies of the last few decades have brought into prominence the occurrence of glacial periods in remote times, probably in early palæozoic times; and as far as the mean temperature of the earth's surface is concerned, it would appear, from the knowledge in our possession, that matters were not very different in those early times from what they now are. [illustration: fig. .] some further remarks will be made in subsequent paragraphs concerning the period of the earth's history at which the geologist is first furnished with definite records, but in the meantime it may be observed that the geologist will do well, when working amongst the strata, to consider that the more active operation of agents, even in times of which he has definite knowledge, may have produced effects which he should be prepared to discover, as their discovery would be of considerable importance, and that he should not be content to infer that because it has been proved that agents operating with the same intensity as that which they have at present, _may_ have produced all the effects which he can actually observe, they therefore necessarily _did_ produce them. _recurrences._ absolute uniformity of conditions is impossible, even in a single area. every change which takes place upon the earth produces conditions somewhat dissimilar from those which previously existed, and these will leave their effects upon the physiography of the area. for this reason, assuming that the conditions have gradually changed from simpler to more complex, every period of time will have been marked by conditions which never prevailed before or afterwards, and these will leave their impress upon the deposits of the period. it is doubtful for instance, as already remarked, whether the exact conditions which gave rise to the extensive deposits of vegetable matter in carboniferous times which now form coal, ever occurred to a like extent in previous or subsequent periods, and accordingly, though we have deposits of coal of other ages, none are so extensive as those of the coal measures. again, as the strata of one period are largely composed of denuded particles of pre-existing strata, which were derived directly or indirectly from igneous rock, the soluble material existing in the igneous rocks must have been gradually eliminated unless restored by other processes, and we might expect to find that early sediments have, on the whole, a larger proportion of soluble silicates than the later ones. besides these changes, there are physical changes which are recurrent, and cause conditions generally similar to pre-existing ones to occur in an area after an interval of dissimilar ones. we have seen that deposits tend to vary according to the distance from the coast, limestone being succeeded by mud, this by sand and gravel, and after subsidence the sand and gravel are succeeded by mud, and that by limestone. these changes will produce some effect upon the organisms, and the recurrence of organisms is a well-known event, of which cases have been cited in a former chapter. again we find, as already pointed out, recurrence of climatic changes, with alternation of glacial and warmer periods, and these may have been very widespread, and would influence the other physical conditions, as well as the distribution of the organisms. vulcanicity may have been more rife at some periods than others, for instance there seems, in the present imperfect state of our knowledge, evidence of enfeebled vulcanicity in later mesozoic times, and of its renewed activity in tertiary times. again, orogenic movements seem to have occurred more extensively at some times than others, as for instance in early upper palæozoic times, at the end of the palæozoic epoch, and in early tertiary times, though this may also be an apparent and not an actual truth, due to imperfect knowledge. in any case, in limited areas, there seem to have been alternations of periods of uplift accompanied by marked orogenic movements, and of widespread depression, accompanied by sedimentation. the subject of rhythmic recurrence is worthy of further study. this recurrence in combination with evolutionary change may account for the apparent marked difference between cambrian and precambrian times, a difference which strikes some geologists as being too great to be accounted for as due to our ignorance only. _organic evolution._ this subject is too wide for more than passing notice in a work of this character. the evidence of palæontology is of extreme importance to the biologist, and indeed, the way in which evolution of organisms has occurred can only be actually demonstrated by reference to palæontology, and the study of palæontology has already given much information concerning the lines on which evolution has proceeded in different groups of organisms. it must be remembered that the major divisions of the invertebrata were in existence in very early times; indeed representatives of most of them are found in the rocks containing the earliest known fauna, that of the _olenellus_ beds of cambrian age. if our present views as to evolution be correct, there is no doubt that the period which elapsed between the appearance of life upon the globe and the existence of the _olenellus_ fauna must have been very great, possibly, as huxley suggested, much greater than that which has elapsed between early cambrian times and the present day. if this be so, however probable it is that we shall carry our knowledge of ancient faunas far back beyond cambrian times, it is extremely improbable that we shall ever get traces of the very earliest faunas which occupied our earth. _geological time._ various attempts have been made to give numerical estimates of the lapse of time which occurred since the earth was formed, or since the earliest known rocks were deposited. these attempts may be classed under two heads, namely, those made by physicists, mainly on evidence obtained otherwise than by a study of the rocks, and those made by geologists by calculating the mean rate of denudation and deposition of the rocks, and estimating the average thickness of the rocks of the geological column. the calculations of physicists as to the age of the earth vary:--lord kelvin assigned , , years as the minimum and , , as the maximum duration of geological time. prof. tait has halved lord kelvin's minimum period, while prof. g. darwin admits the possibility of the lapse of , , years. the estimates made by geologists, which will appeal more directly to the geological student, also vary considerably, though they bear some proportion to those which have been put forward by the physicists. prof. s. haughton[ ] assigned a period of , , years for the accumulation of the rocks of the geological column; mr clifton ward[ ] one of , , years, after studying the rocks of the english lake district, and allowing for the gaps in the succession; mr a. r. wallace[ ] further lowers the time for the formation of the column to , , years; sir a. geikie[ ] gives , , years as the minimum and , , as the maximum; while mr j. g. goodchild has lately[ ] estimated the period at over , , years. [footnote : _nature_, vol. xviii. p. .] [footnote : ward, j. c., 'the physical history of the english lake district,' _geol. mag._ dec , vol. vi. p. .] [footnote : wallace, a. r., _island life_, chap. x.] [footnote : geikie, sir a., 'presidential address to the british association,' _report brit. assoc._, .] [footnote : goodchild, j. g., _proc. roy. soc. edinburgh_, vol. xiii. p. .] interesting as these figures are, they probably convey little to the ordinary reader, and it is doubtful whether the geologist is really affected by them to any extent when picturing to himself the vast duration of geological time. one numerical estimate probably does impress him, namely that made by croll as to the date of the great ice age, for if the ice age be so remote as croll imagined, the commencement of earth-history must be inconceivably more remote; as croll's estimate is not generally accepted, it is doubtful how far geologists are thus influenced, and probably the fact which does impress them most, leaving fossils out of account, is the very little change which has occurred in historic or even in prehistoric times as compared with the vast changes which are familiar to them after studying the strata of the geological column. it is, after all, the succession of varied faunas which really gives students of the rocks the most convincing proof of the vast periods of geological time. if anyone doubts this assertion, let him consider what impression would be made upon him by observing the several thousand feet of strata of the column if none of them contained any organisms. cognisant as he is of the slow rate of change of existing organisms, the fact that fauna has succeeded fauna in past times brings home to him in an unmistakeable manner the great antiquity of the earliest fossiliferous rocks, and as our detailed knowledge of these faunas increases the impression of great lapse of time is intensified. and if the earliest fossiliferous rocks be of such vast antiquity, and, as has been remarked, the period of their formation is comparatively recent with reference to the actual commencement of earth-history, the latter must indeed be inconceivably remote, and numerical estimates can do but little to familiarise us with the significance of the vast time which has rolled by since the world's birthday. index. abraum salts, Æolian rocks, , , age, definition of, albian series, , algonkian rocks, ampthill clay, angelin, n. p., , , aptian series, , aqueous rocks, archæan rocks, ardmillan series, ardwick stage, arenaceous rocks, arvonian rocks, asaphus fauna, ashgill series, , , - ashprington series, astian series, atlantis, aveline, w. t., aymestry limestone, , bagshot beds, , bajocian series, , bala limestone, bala series, barr series, barrande, j., , , , , barrois, c., barrow, g., barton beds, bath oolites, bathonian series, , bed, bedding plane, bell, a., belt, t., , bembridge beds, bertrand, m., , birkhill shales, black jura, blake, j. f., - blanford, w. t., , , , , bonney, t. g., , , boulder clay, bracklesham beds, bradford clay, break, palæontological, ; physical, bristow, h., brockram, brögger, w. c., - brongniart, h., brongniart, c., bronze age, - brown jura, bunter sandstone, , - bure valley beds, buttery clay, caerfai beds, , , calcareous rocks, caldicote series, callaway, c., - callovian series, , cambrian faunas, - cambrian system, - caradoc series, , - carbonaceous rocks, carboniferous fauna and flora, - carboniferous limestone, , , carboniferous system, - carnic beds, cataclastic rocks, cave man, cenomanian series, ceratopyge fauna, chalk, , , chalk marl, chemically-formed rocks, , chillesford crag, chronological terms, clastic rocks, climatic conditions, , , , climatic zones, in jurassic times, ; in cretaceous times, clymenian beds, coal, - coal measures, ; mode of formation of, - coblenzian beds, collyweston slate, colonies, theory of, contemporaneity of strata, continents, growth of, - cope, e., corallian series, , coralline crag, , cornbrash, cornstones, coutchiching series, crags, - cretaceous fauna and flora, - cretaceous system, - croll, j., , , cromer forest series, , , cromer till, cucullæa beds, cuvier, baron g., , dalradian rocks, dana, j. d., danian series, darwin, c., , darwin, g., daubrée, a., david, t. w. e., davis, w. m., , dawkins, w. b., , , , , deep-sea deposits, de hayes, g. p., de la beche, sir h., deposition, order of, , derivative rocks, devonian flora and fauna, - devonian system, - dictyograptus fauna, dimetian rocks, dogger, downtonian beds, dwyka conglomerate, edwards, f. e., eifelian beds, encrinurus fauna, englacial deposits, entomis slates, eocene fauna and flora, , eocene rocks, - eozoon canadense, eparchæan rocks, epeirogenic movements, epiclastic rocks, ; simulation by cataclastic rocks, , epoch, definition of, estuarine series, etheridge, r., ettingshausen, baron von, evans, sir j., , , , evolution, , feistmantel, o., fenland, fluvio-glacial deposits, foreland grits, forest marble, forest period, , - fossils, ; strata identifiable by, ; mode of occurrence of, ; relative value of, ; remanié, ; geographical distribution of, ; as indicative of physical conditions, fossil zone, foster, c. le n., fox, h., freshwater deposits, ; distinction from marine, fuller's earth, fusulina beds, gala beds, gannister stage, gardner, j. s., gault, , geikie, sir a., , , , , , , , , , , , , , geikie, j., girvan type, glacial deposits, permo-carboniferous, ; pleistocene, - glacial period, - glenkiln shales, , glossopteris flora, , , godwin-austen, r. a. c., gondwana series, gondwanaland, , goniatite beds, goodchild, j. g., , , , great ice age, , great oolite, , gregory, j. g., green, a. h., , , greensand, lower, ; upper, groom, t. t., gshellian beds, , hampshire basin, hangman grits, harker, a., , harkness, r., harmer, f. w., harpes fauna, harrison, w. j., hartfell shales, , hastings sands, , haughton, s., headon beds, heim, a., hempstead beds, hercynian systems of folds, hicks, h., , , , , , , , , , hickson, s. j., hill, a., hill, e., hilton shales, , hind, w., hinde, g. j., , hippurite limestone, , hirnant limestone, homotaxis, hughes, t. mck., , , hull, e., , , , hume, w. f., hunt, a. r., huronian system, hutton, j., huxley, t. h., , igneous rocks, - ilfracombe beds, inferior oolite, inverted strata, ; detection of, iron age, , judd, j. w., , jukes, j. b., jukes-browne, a. j., , , jurassic beds, jurassic fauna and flora, , jurassic system, - kayser, e., , keewatin series, kelvin, lord, kendall, p., keuper beds, , , kidston, b., kimmeridge clay, kimmeridgian series, king, w., kjerulf, th., koninck, l. de, kupferschiefer, lake, p., , lamina, lamplugh, g. w., , , lapworth, c., , , , , - , , , laurentian rocks, lawson, a. c., , lehmann, j., lenham beds, lewis, h. c., lias, , liassian series, , lincolnshire limestone, , lincombe and warberry grits, lindström, g., lingula flags, , , linnarsson, j. g. o., llandeilo limestone, llandeilo series, , llandovery series, - loess, logan, sir w., london basin, london clay, , , longmyndian rocks, lower london tertiary beds, , lubbock, sir j., , ludlow series, - lydekker, r., lyell, sir c., , , , , , , , lynton slates, mccoy, sir f., mcmahon, c. a., madsen, h. p., magnesian limestone, - malm, maps, geological, , ; use of, , , marcou, j., , marine deposits, ; nature of fossils in, marl slate, , marlstone, marsh, o. c., marwood beds, matthew, g. f., - , meadfoot sands, mechanically formed rocks, , mello, j. m., mendip system of folds, menevian beds, , , , metamorphic rocks, miall, l. c., michell, j., , millepore oolite, , miller, h., millet seed sands, millstone grit, miocene period, - moffat shales, , mojsisovics, e. von, , morgan, c. ll., morte slates, moscovian beds, , mountain limestone, murchison, sir r. i., , , , murray, sir j., muschelkalk, , , nehring, a., , neobolus fauna, neocomian series, - neolithic age, - neumayr, m., , newton, e. t., nicholson, h. a., , noachian deluge, noetling, f., nordenskjöld, a. e., , noric beds, northamptonshire sands, norwich crag, , nummulitic limestone, old red sandstone, , , , , oldham, r. d., oldhaven beds, , olenellus fauna, , , - olenus fauna, , , oligocene beds, , oligocene fauna and flora, oolite, ordovician faunas, , ordovician system, - organically formed rocks, , , orogenic movements, osborne beds, owen, sir r., oxford clay, oxford oolite, oxfordian series, , palæolithic fauna and flora, - palæolithic man, , - palæolithic period, - palæontological break, palæo-physiography, paradoxides fauna, , , peat deposits, , pebble beds of bunter, pebidian rocks, pengelly, w., pennant stage, pennine system of folds, penrith sandstone, , , period, definition of, permanence of ocean basins, - permian fauna and flora, - permian system, - permo-carboniferous fauna and flora, , permo-carboniferous glacial deposits, permo-carboniferous period, - phillips, j., , , physical break, pickwell down sandstone, pilton beds, plaisancean series, planes of lamination, planes of stratification, pleistocene fauna and flora, , pleistocene period, - pliocene fauna and flora, pliocene period, - portland oolites, portlandian series, , prado, c. de, precambrian rocks, ; mode of formation of, preller, c. s. du r., prestwich, sir j., , , productus limestones, , , protolenus fauna, pseudo-stromatism, purbeckian series, , pyroclastic rocks, quader sandstone, ramsay, sir a. c., , , , reading beds, recurrences, red crag, , reid, c., , , , , renard, a., reversed fault, rhætic beds, rhiwlas limestone, richthofen, baron von, , ridley, h. n., river drift man, rotherham red rock, rothliegende, rouelle, st bees sandstone, st erth beds, salopian beds, salter, j. w., , , scarbro' limestone, , schists, crystalline, , , , scilla, a., screes, scrope, g. p., sections, geological, ; use of, sedimentary rocks, sedgwick, a., , , , , senonian series, series, definition of, seward, a. c., , sigmoidal structure, siliceous rocks, silurian faunas, , silurian system, - simulation of structures, sinemurian series, , smith, w., , - , , soil, solenhofen slate, sollas, w. j., solva beds, , , , speckled sandstone, , speeton series, spencer, h., spirorbis limestone, stages, definition of, steppe period, , - stonesfield slate, strachey, j., strahan, a., , strata, ; classification of, , stratification, stratified rocks, ; composition of, ; origin of, ; classification of, , ; symbols to represent, stratigraphical geology, aim of, ; w. smith, founder of, , - suess, e., , , , superposition, law of, surveying, geological, systems, definition of, talchir stage, , tarannon shales, - teall, j. j. h., terrestrial rocks, thanet sands, thinning out, thrust plane, ; detection of, , tiddeman, b. h., , , till, time, geological, - toarcian series, , topley, w., , torridonian beds, - tremadoc slates, , , , triassic fauna and flora, - triassic system, - ; ammonite zones of, trinucleus fauna, tullberg, s. a., turonian series, unconformity, , , underclays, uniformitarianism, - uriconian rocks, ussher, w. a. e., valentian beds, verneuil, e. p. de, volcanic rocks, cambrian, ; carboniferous, ; devonian, , ; eocene, , ; ordovician, - ; precambrian, vulcanicity, waagen, w., , walcott, c. d., , , , , wallace, a. r., , , , , ward, j. c., , , , warming, e., watts, w. w., , , wealden beds, , webster, t., weissliegende, wenlock limestone, , wenlock series, - wenlock shale, - werfener schichten, werner, a. g., weybourne crag, whewell, w., whidbourne, g. f., white jura, whitehaven sandstone, whitehurst, j., , wiman, c., wood, s. v., , woodward, h., woodward, h. b., , , woodward, j., - woodward, s. p., , woolhope limestone, woolwich beds, wright, g. f., yoredale series, zanclean series, zechstein, zone, fossil, ; ammonite, , ; graptolite, cambridge: printed by j. and c. f. clay, at the university press. cambridge natural science manuals. biological series. general editor, a. e. shipley, m.a. =elementary palæontology--invertebrate= h. woods, m.a., f.g.s. _s._ =elements of botany= f. darwin, m.a., f.r.s. _s._ _d._ =practical physiology of plants= f. darwin, & e. h. acton, m.a. _s._ _d._ =practical morbid anatomy= h. d. rolleston, m.d., f.r.c.p. & a. a. kanthack, m.d., m.r.c.p. _s._ =zoogeography= f. e. beddard, m.a., f.r.s. _s._ =flowering-plants and ferns= j. c. willis, m.a. in two vols. _s._ _d._ =the vertebrate skeleton= s. h. reynolds, m.a. _s._ _d._ =fossil plants= a. c. seward, m.a., f.g.s. vols. vol. i. _s._ =outlines of vertebrate palæontology= a. s. woodward. _s._ =the soluble ferments and fermentation= j. reynolds green, sc.d., f.r.s. _s._ =zoology= e. w. macbride, m.a. and a. e. shipley, m.a. [_in the press._ physical series. general editor, r. t. glazebrook, m.a., f.r.s. =heat and light= r. t. glazebrook, m.a., f.r.s. _s._ " " in two separate parts " " _each_ _s._ =mechanics and hydrostatics= r. t. glazebrook, m.a., f.r.s. _s._ _d._ " " in three separate parts part i. =dynamics= " " _s._ " ii. =statics= " " _s._ " iii. =hydrostatics= " " _s._ =solution and electrolysis= w. c. d. whetham, m.a. _s._ _d._ [_out of print._ =electricity and magnetism= r. t. glazebrook, m.a., f.r.s. _in preparation._ geological series. =petrology for students= a. harker, m.a., f.g.s. _s._ _d._ =handbook to the geology of cambs= f. r. c. reed, m.a. _s._ _d._ =the principles of stratigraphical geology= j. e. marr, m.a. _s._ =crystallography= prof. w. j. lewis, m.a. _s._ _net._ * * * * * =laboratory note-books of= } { l. r. wilberforce, m.a., and =elementary physics= } { t. c. fitzpatrick, m.a. i. =mechanics and hydrostatics.= ii. =heat and optics.= iii. =electricity and magnetism.= _each_ _s._ _other volumes are in preparation and will be announced shortly._ _press opinions._ biological series. =a manual and dictionary of the flowering plants and ferns.= morphology, natural history and classification. alphabetically arranged. by j. c. willis, m.a., gonville and caius college. in two volumes. crown vo. with illustrations. _s._ _d._ _bookman._ one of the most useful books existing for students of botany.... the student who has this book and the chances which kew, or even one of the smaller gardens, affords him, will make a steady and really scientific progress. =elements of botany.= by f. darwin, m.a., f.r.s. second edition. crown vo. with numerous illustrations. _s._ _d._ _journal of education._ a noteworthy addition to our botanical literature. =practical physiology of plants.= by f. darwin, m.a., f.r.s., fellow of christ's college, cambridge, and reader in botany in the university, and e. h. acton, m.a., late fellow and lecturer of st john's college, cambridge. with 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the british museum. demy vo. _s._ _athenæum._ mr woodward, in studying vertebrate fossils for the purpose of this volume, takes the biological view, and has designed his work primarily for the assistance of students of vertebrate morphology and zoology. mindful, however, of the geological side of the subject, he has introduced a chapter on the succession of the vertebrate faunas, offering a brief but convenient summary of the distribution of vertebrate life throughout geologic time. the author is to be congratulated on having produced a work of exceptional value, dealing with a difficult subject in a thoroughly sound manner. =the vertebrate skeleton.= by s. h. reynolds, m.a., trinity college. crown vo. _s._ _d._ _british medical journal._ a volume which will certainly take its place amongst the standard text-books of the day. biological series. =practical morbid anatomy.= by h. d. rolleston, m.d., f.r.c.p., fellow of st john's college, cambridge, assistant physician and lecturer on 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itself maintains an honoured place in the university science course. _nature._ the author and the university press may be congratulated on the completion of a treatise worthy of the subject and of the university. =petrology for students.= an introduction to the study of rocks under the microscope. by a. harker, m.a., f.g.s., fellow of st john's college, and demonstrator in geology (petrology) in the university of cambridge. crown vo. second edition, revised. _s._ _d._ _nature._ no better introduction to the study of petrology could be desired than is afforded by mr harker's volume. london: c. j. clay and sons, cambridge university press warehouse, ave maria lane and h. k. lewis, , gower street, w.c. _medical publisher and bookseller._ transcriber's note any obsolete or alternate spelling and grammar was retained. all obvious typographical errors were corrected. although hyphenation of words has been standardized to the most prevalent occurrence, the six occurrences of fresh-water were not converted to freshwater ( occurrences) due to usage. corrected spellings: godwin-austen (p. ); whidbourne (p. ); and ichthyopterygia (p. ). images of public domain material from the google print project.) observations on mount vesuvius, mount etna, and other volcanos: in a series of letters, addressed to the royal society, from the honourable sir w. hamilton, k.b. f.r.s. his majesty's envoy extraordinary and plenipotentiary at the court of naples. to which are added, explanatory notes by the author, hitherto unpublished. a new edition. london, printed for t. cadell, in the strand. m dcc lxxiv. the editor to the public. having mentioned to sir william hamilton the general desire of all lovers of natural history, that his letters upon the subject of volcanos should be collected together in one volume, particularly for the convenience of such as may have an opportunity of visiting the curious spots described in them: he was not only pleased to approve of my having undertaken this publication, but has likewise favoured with the additional explanatory notes and drawings, the public's most obliged, and devoted humble servant, t. cadell. may , . observations on mount vesuvius, &c. letter i. to the right honourable the earl of morton, president of the royal society. naples, june , . my lord, as i have attended particularly to the various changes of mount vesuvius, from the th of november , the day of my arrival at this capital; i flatter myself, that my observations will not be unacceptable to your lordship, especially as this volcano has lately made a very considerable eruption. i shall confine myself merely to the many extraordinary appearances that have come under my own inspection, and leave their explanation to the more learned in natural philosophy. during the first twelvemonth of my being here, i did not perceive any remarkable alteration in the mountain; but i observed, the smoke from the volcano was much more considerable in bad weather than when it was fair[ ]; and i often heard (even at naples, six miles from vesuvius) in bad weather, the inward explosions of the mountain. when i have been at the top of mount vesuvius in fair weather, i have sometimes found so little smoke, that i have been able to see far down the mouth of the volcano; the sides of which were incrusted with salts and mineral of various colors, white, green, deep and pale yellow. the smoke that issued from the mouth of the volcano in bad weather was white, very moist, and not near so offensive as the sulphureous steams from various cracks on the sides of the mountain. towards the month of september last, i perceived the smoke to be more considerable, and to continue even in fair weather; and in october i perceived sometimes a puff of black smoke shoot up a considerable height in the midst of the white, which symptom of an approaching eruption grew more frequent daily; and soon after, these puffs of smoke appeared in the night tinged like clouds with the setting sun. about the beginning of november, i went up the mountain: it was then covered with snow; and i perceived a little hillock of sulphur had been thrown up, since my last visit there, within about forty yards of the mouth of the volcano; it was near six feet high, and a light blue flame issued constantly from its top. as i was examining this phænomenon, i heard a violent report; and saw a column of black smoke, followed by a reddish flame, shoot up with violence from the mouth of the volcano; and presently fell a shower of stones, one of which, falling near me, made me retire with some precipitation, and also rendered me more cautious of approaching too near, in my subsequent journies to vesuvius. from november to the th of march, the date of the beginning of this eruption, the smoke increased, and was mixed with ashes, which fell, and did great damage to the vineyards in the neighbourhood of the mountain[ ]. a few days before the eruption i saw (what pliny the younger mentions having seen, before that eruption of vesuvius which proved fatal to his uncle) the black smoke take the form of a pine-tree. the smoke, that appeared black in the day-time, for near two months before the eruption, had the appearance of flame in the night. on good friday, the th of march, at o'clock at night, the lava began to boil over the mouth of the volcano, at first in one stream; and soon after, dividing itself into two, it took its course towards portici. it was preceded by a violent explosion, which caused a partial earthquake in the neighbourhood of the mountain; and a shower of red hot stones and cinders were thrown up to a considerable height. immediately upon sight of the lava, i left naples, with a party of my countrymen, whom i found as impatient as myself to satisfy their curiosity in examining so curious an operation of nature. i passed the whole night upon the mountain; and observed that, though the red hot stones were thrown up in much greater number and to a more considerable height than before the appearance of the lava, yet the report was much less considerable than some days before the eruption. the lava ran near a mile in an hour's time, when the two branches joined in a hollow on the side of the mountain, without proceeding farther. i approached the mouth of the volcano, as near as i could with prudence; the lava had the appearance of a river of red hot and liquid metal, such as we see in the glass-houses, on which were large floating cinders, half lighted, and rolling one over another with great precipitation down the side of the mountain, forming a most beautiful and uncommon cascade; the color of the fire was much paler and more bright the first night than the subsequent nights, when it became of a deep red, probably owing to its having been more impregnated with sulphur at first than afterwards. in the day-time, unless you are quite close, the lava has no appearance of fire; but a thick white smoke marks its course. the th, the mountain was very quiet, and the lava did not continue. the th, it began to flow again in the same direction, whilst the mouth of the volcano threw up every minute a girandole of red hot stones, to an immense height. the st, i passed the night upon the mountain: the lava was not so considerable as the first night; but the red hot stones were perfectly transparent, some of which, i dare say of a ton weight, mounted at least two hundred feet perpendicular, and fell in, or near, the mouth of a little mountain, that was now formed by the quantity of ashes and stones, within the great mouth of the volcano, and which made the approach much safer than it had been some days before, when the mouth was near half a mile in circumference, and the stones took every direction. mr. hervey, brother to the earl of bristol, was very much wounded in the arm some days before the eruption, having approached too near; and two english gentlemen with him were also hurt. it is impossible to describe the beautiful appearance of these girandoles of red hot stones, far surpassing the most astonishing artificial fire-work. from the st of march to the th of april, the lava continued on the same side of the mountain, in two, three, and sometimes four branches, without descending much lower than the first night. i remarked a kind of intermission in the fever of the mountain[ ], which seemed to return with violence every other night. on the th of april, at night, the lava disappeared on the side of the mountain towards naples, and broke out with much more violence on the side next the _torre dell' annunciata_. i passed the whole day and the night of the twelfth upon the mountain, and followed the course of the lava to its very source: it burst out of the side of the mountain, within about half a mile of the mouth of the volcano, like a torrent, attended with violent explosions, which threw up inflamed matter to a considerable height, the adjacent ground quivering like the timbers of a water-mill; the heat of the lava was so great, as not to suffer me to approach nearer than within ten feet of the stream, and of such a consistency (though it appeared liquid as water) as almost to resist the impression of a long stick, with which i made the experiment; large stones thrown on it with all my force did not sink, but, making a slight impression, floated on the surface, and were carried out of sight in a short time; for, notwithstanding the consistency of the lava, it ran with amazing velocity; i am sure, the first mile with a rapidity equal to that of the river severn, at the passage near bristol. the stream at its source was about ten feet wide, but soon extended itself, and divided into three branches; so that these rivers of fire, communicating their heat to the cinders of former lavas, between one branch and the other, had the appearance at night of a continued sheet of fire, four miles in length, and in some parts near two in breadth. your lordship may imagine the glorious appearance of this uncommon scene, such as passes all description. the lava, after having run pure for about a hundred yards, began to collect cinders, stones, &c.; and a scum was formed on its surface, which in the day-time had the appearance of the river thames, as i have seen it after a hard frost and great fall of snow, when beginning to thaw, carrying down vast masses of snow and ice. in two places the liquid lava totally disappeared, and ran in a subterraneous passage for some paces; then came out again pure, having left the scum behind. in this manner it advanced to the cultivated parts of the mountain; and i saw it, the same night of the th, unmercifully destroy a poor man's vineyard, and surround his cottage, notwithstanding the opposition of many images of st. januarius, that were placed upon the cottage, and tied to almost every vine. the lava, at the farthest extremity from its source, did not appear liquid, but like a heap of red hot coals, forming a wall in some places ten or twelve feet high, which rolling from the top soon formed another wall, and so on, advancing slowly, not more than about thirty feet in an hour[ ]. the mouth of the volcano has not thrown up any large stones since the second eruption of lava on the th of april; but has thrown up quantities of small ashes and pumice stones, that have greatly damaged the neighbouring vineyards. i have been several times at the mountain since the th; but, as the eruption was in its greatest vigour at that time, i have ventured to dwell on, and i fear tire your lordship with, the observations of that day. in my last visit to mount vesuvius, the d of june, i still found that the lava continued; but the rivers were become rivulets, and had lost much of their rapidity. the quantity of matter thrown out by this eruption is greater than that of the last in the year ; but the damage to the cultivated lands is not so considerable, owing to its having spread itself much more, and its source being at least three miles higher up. this eruption seems now to have exhausted itself; and i expect in a few days to see vesuvius restored to its former tranquillity. mount etna in sicily broke out on the th of april; and made a lava, in two branches, at least six miles in length, and a mile in breadth; and, according to the description given me by mr. wilbraham, (who was there, after having seen with me part of the eruption of mount vesuvius) resembles it in every respect, except that mount etna, at the place from whence the lava flowed (which was twelve miles from the mouth of the volcano), threw up a fountain of liquid inflamed matter to a considerable height; which, i am told, mount vesuvius has done in former eruptions. i beg pardon for having taken up so much of your time; and yet i flatter myself, that my description, which i assure your lordship is not exaggerated, will have afforded you some amusement. i have the honour to be, my lord, your lordship's most obedient and most humble servant, william hamilton. * * * * * naples, february , . since the account of the eruption of mount vesuvius, which i had the honour of giving to your lordship, in my letter of the th of june last; i have only to add, that the lava continued till about the end of november, without doing any great damage, having taken its course over antient lavas. since the cessation of this eruption, i have examined the crater, and the crack on the side of the mountain towards _torre dell' annunciata_, about a hundred yards from the crater from whence this lava issued: and i found therein some very curious salts and sulphurs; a specimen of each sort i have put into bottles myself, even upon the mountain, that they might not lose any of their force, and have sent them in a box directed to your lordship, as you will see, by the bill of lading: i am sure, you will have a pleasure in seeing them analyzed[ ]. i have also packed in the same box some lava, and cinders, of the last eruption; there is one piece in particular very curious, having the exact appearance of a cable petrified. i shall be very happy if these trifles should afford your lordship a moment's amusement. it is very extraordinary, that i cannot find, that any chemist here has ever been at the trouble of analyzing the productions of vesuvius. the deep yellow, or orange-color salts, of which there are two bottles, i fetched out of the very crater of the mountain, in a crevice that was indeed very hot. it seems to me to be powerful, as it turns silver black in an instant, but has no effect upon gold. if your lordship pleases, i will send you by another opportunity specimens of the sulphurs and salts of the solfa terra, which seem to be very different from these. within these three days, the fire has appeared again on the top of vesuvius, and earthquakes have been felt in the neighbourhood of the mountain. i was there on saturday with my nephew lord greville; we heard most dreadful inward grumblings, rattling of stones, and hissing; and were obliged to leave the crater very soon, on account of the emission of stones. the black smoak arose, as before the last eruption; and i saw every symptom of a new eruption, of which i shall not fail to give your lordship an exact account. letter ii. to the right honourable the earl of morton, president of the royal society. naples, december , . my lord, the favourable reception, which my account of last year's eruption of mount vesuvius met with from your lordship; the approbation which the royal society was pleased to shew, by having ordered the same to be printed in their philosophical transactions; and your lordship's commands, in your letter of the d instant; encourage me to trouble you with a plain narrative of what came immediately under my observation, during the late violent eruption, which began october , , and is reckoned to be the twenty-seventh since that, which, in the time of titus, destroyed herculaneum and pompeii. the eruption of continued in some degree till the th of december, about nine months in all[ ]; yet in that space of time the mountain did not cast up a third of the quantity of lava, which it disgorged in only seven days, the term of this last eruption. on the th of december, last year, within the ancient crater of mount vesuvius, and about twenty feet deep, there was a crust, which formed a plain, not unlike the solfa terra in miniature; in the midst of this plain was a little mountain, whose top did not rise so high as the rim of the ancient crater. i went into this plain, and up the little mountain, which was perforated, and served as the principal chimney to the volcano: when i threw down large stones, i could hear that they met with many obstructions in their way, and could count a hundred moderately before they reached the bottom. vesuvius was quiet till march , when it began to throw up stones from time to time; in april, the throws were more frequent, and at night fire was visible on top of the mountain, or, more properly speaking, the smoak, which hung over the crater, was tinged by the reflection of the fire within the volcano. these repeated throws of cinders, ashes, and pumice stones, increased the little mountain so much, that in may the top was visible above the rim of the ancient crater. the th of august, there issued a small stream of lava, from a breach in the side of this little mountain, which gradually filled the valley between it and the ancient crater; so that, the th of september, the lava overflowed the ancient crater, and took its course down the sides of the great mountain; by this time, the throws were much more frequent, and the red hot stones went so high as to take up ten seconds in their fall. padre torre, a great observer of mount vesuvius, says they went up above a thousand feet. the th of october, the height of the little mountain (formed in about eight months) was measured by don andrea pigonati, a very ingenious young man, in his sicilian majesty's service, who assured me that its height was french feet. from my villa, situated between herculaneum and pompeii, near the convent of the calmaldolese (marked in plate i.) i had watched the growing of this little mountain; and, by taking drawings of it from time to time, i could perceive its increase most minutely. i make no doubt but that the whole of mount vesuvius has been formed in the same manner; and as these observations seem to me to account for the various irregular strata, which are met with in the neighbourhood of volcanos, i have ventured to inclose, for your lordship's inspection, a copy of the abovementioned drawings. (plate iii.) the lava continued to run over the ancient crater in small streams, sometimes on one side, and sometimes on another, till the th of october, when i took particular notice that there was not the least lava to be seen; owing, i imagine, to its being employed in forcing its way towards the place where it burst out the following day. as i had, contrary to the opinion of most people here, foretold the approaching eruption[ ], and had observed a great fermentation in the mountain after the heavy rains which fell the th and th of october; i was not surprized, on the th following, at seven of the clock in the morning, to perceive from my villa every symptom of the eruption being just at hand. from the top of the little mountain issued a thick black smoak, so thick that it seemed to have difficulty in forcing its way out; cloud after cloud mounted with a hasty spiral motion, and every minute a volley of great stones were shot up to an immense height in the midst of these clouds; by degrees, the smoak took the exact shape of a huge pine-tree, such as pliny the younger described in his letter to tacitus, where he gives an account of the fatal eruption in which his uncle perished[ ]. this column of black smoak, after having mounted an extraordinary height, bent with the wind towards caprea, and actually reached over that island, which is not less than twenty-eight miles from vesuvius. i warned my family, not to be alarmed, as i expected there would be an earthquake at the moment of the lava's bursting out; but before eight of the clock in the morning i perceived that the mountain had opened a mouth, without noise, about a hundred yards lower than the ancient crater, on the side towards the monte di somma; and i plainly perceived, by a white smoak, which always accompanies the lava, that it had forced its way out: as soon as it had vent, the smoak no longer came out with that violence from the top. as i imagined that there would be no danger in approaching the mountain when the lava had vent, i went up immediately, accompanied by one peasant only. i passed the hermitage ( . in plate i.), and proceeded as far as the spot marked (x), in the valley between the mountain of somma and that of vesuvius, which is called atrio di cavallo. i was making my observations upon the lava, which had already, from the spot (e) where it first broke out, reached the valley; when, on a sudden, about noon, i heard a violent noise within the mountain, and at the spot (c), about a quarter of a mile off the place where i stood, the mountain split; and, with much noise, from this new mouth, a fountain of liquid fire shot up many feet high, and then, like a torrent, rolled on directly towards us. the earth shook, at the same time that a volley of pumice stones fell thick upon us; in an instant, clouds of black smoak and ashes caused almost a total darkness; the explosions from the top of the mountain were much louder than any thunder i ever heard, and the smell of the sulphur was very offensive. my guide, alarmed, took to his heels; and i must confess, that i was not at my ease. i followed close, and we ran near three miles without stopping; as the earth continued to shake under our feet, i was apprehensive of the opening of a fresh mouth, which might have cut off our retreat. i also feared that the violent explosions would detach some of the rocks off the mountain somma, under which we were obliged to pass; besides, the pumice-stones, falling upon us like hail, were of such a size as to cause a disagreeable sensation upon the part where they fell. after having taken breath, as the earth still trembled greatly, i thought it most prudent to leave the mountain, and return to my villa; where i found my family in a great alarm, at the continual and violent explosions of the volcano, which shook our house to its very foundation, the doors and windows swinging upon their hinges. about two of the clock in the afternoon another lava forced its way out of the same place from whence came the lava last year, at the spot marked b (in plate ii.); so that the conflagration was soon as great on this side of the mountain, as on the other which i had just left. the noise and smell of sulphur increasing, we removed from our villa to naples; and i thought proper, as i passed by portici, to inform the court of what i had seen; and humbly offered it as my opinion, that his sicilian majesty should leave the neighbourhood of the threatening mountain. however, the court did not leave portici till about twelve of the clock, when the lava had reached as far as ( . in plate i.)--i observed, in my way to naples, which was in less than two hours after i had left the mountain, that the lava had actually covered three miles of the very road through which we had retreated. it is astonishing that it should have run so fast; as i have since seen, that the river of lava, in the atrio di cavallo, was sixty and seventy feet deep, and in some places near two miles broad. when his sicilian majesty quitted portici, the noise was greatly increased; and the concussion of the air from the explosions was so violent, that, in the king's palace, doors and windows were forced open; and even one door there, which was locked, was nevertheless burst open. at naples, the same night, many windows and doors flew open; in my house, which is not on the side of the town next vesuvius, i tried the experiment of unbolting my windows[ ], when they flew wide open upon every explosion of the mountain. besides these explosions, which were very frequent, there was a continued subterraneous and violent rumbling noise, which lasted this night about five hours. i have imagined, that this extraordinary noise might be owing to the lava in the bowels of the mountain having met with a deposition of rain water; and that the conflict between the fire and the water may, in some measure, account for so extraordinary a crackling and hissing noise. padre torre, who has wrote so much and so well upon the subject of mount vesuvius, is also of my opinion. and indeed it is natural to imagine, that there may be rain-water lodged in many of the caverns of the mountain; as, in the great eruption of mount vesuvius in , it is well attested, that several towns, among which portici and torre del greco, were destroyed, by a torrent of boiling water having burst out of the mountain with the lava, by which thousands of lives were lost. about four years ago, mount etna in sicily threw up hot water also, during an eruption. the confusion at naples this night cannot be described; his sicilian majesty's hasty retreat from portici added to the alarm; all the churches were opened and filled; the streets were thronged with processions of saints: but i shall avoid entering upon a description of the various ceremonies that were performed in this capital, to quell the fury of the turbulent mountain. tuesday the th, it was impossible to judge of the situation of vesuvius, on account of the smoak and ashes, which covered it entirely, and spread over naples also, the sun appearing as through a thick london fog, or a smoaked glass; small ashes fell all this day at naples. the lavas on both sides of the mountain ran violently; but there was little or no noise till about nine o'clock at night, when the same uncommon rumbling began again, accompanied with explosions as before, which lasted about four hours: it seemed as if the mountain would split in pieces; and, indeed, it opened this night almost from the spot e to c (in plate i.). the annexed plans were taken upon the spot at this time, when the lavas were at their height; and i do not think them exaggerated. the parisian barometer was, as yesterday, at , and fahrenheit's thermometer at degrees; whereas, for some days preceding the eruption, it had been at and . during the confusion of this night, the prisoners in the public jail attempted to escape, having wounded the jailer; but were prevented by the troops. the mob also set fire to the cardinal archbishop's gate, because he refused to bring out the relicks of saint januarius. wednesday st, was more quiet than the preceding days, though the lavas ran briskly. portici was once in some danger, had not the lava taken a different course when it was only a mile and a half from it; towards night, the lava slackened. thursday d, about ten of the clock in the morning, the same thundering noise began again, but with more violence than the preceding days; the oldest men declared, they had never heard the like; and, indeed, it was very alarming: we were in expectation every moment of some dire calamity. the ashes, or rather small cinders, showered down so fast, that the people in the streets were obliged to use umbrellas, or flap their hats; these ashes being very offensive to the eyes. the tops of the houses, and the balconies, were covered above an inch thick with these cinders[ ]. ships at sea, twenty leagues from naples, were also covered with them, to the great astonishment of the sailors. in the midst of these horrors, the mob, growing tumultuous and impatient, obliged the cardinal to bring out the head of saint januarius, and go with it in procession to the ponte maddalena, at the extremity of naples, towards vesuvius; and it is well attested here, that the eruption ceased the moment the saint came in sight of the mountain; it is true, the noise ceased about that time, after having lasted five hours, as it had done the preceding days. friday d, the lavas still ran, and the mountain continued to throw up quantities of stones from its crater; there was no noise heard at naples this day, and but little ashes fell there. saturday th, the lava ceased running; the extent of the lava, from the spot c (plate i.), where i saw it break out, to its extremity f, where it surrounded the chapel of saint vito, is above six miles. in the atrio di cavallo, and in a deep valley that lies between vesuvius ( .) and the hermitage ( .), the lava is in some places near two miles broad, and in most places from sixty to seventy feet deep; at ( .), the lava ran down a hollow way, called fossa grande, made by the currents of rain water; it is not less than two hundred feet deep, and a hundred broad; yet the lava in one place has filled it up. i could not have believed that so great a quantity of matter could have been thrown out in so short a time, if i had not since examined the whole course of the lava myself. this great compact body will certainly retain some heat many months[ ]; at this time, much rain having fallen for some days past, the lava smoaks, as if it ran afresh: and about ten days ago, when i was up the mountain with lord stormont, we thrust sticks into the crevices of the lava, which took fire immediately: but to proceed with my journal. the th, vesuvius continued to throw up stones as on the preceding days: during the whole of this eruption, it had differed in this circumstance from the eruption of , when no stones were thrown out of the crater from the moment the lava ran freely. sunday th, small ashes fell all day at naples; they issued from the crater of the volcano, and formed a vast column, as black as the mountain itself, so that the shadow of it was marked out on the surface of the sea; continual flashes of forked or zig-zag lightning shot from this black column, the thunder of which was heard in the neighbourhood of the mountain, but not at naples: there were no clouds in the sky at this time, except those of smoak issuing from the crater of vesuvius. i was much pleased with this phænomenon, which i had not seen before in that perfection[ ]. monday th, the smoak continued, but not so thick, neither were there any flashes of the mountain lightning. as no lava has appeared after this column of black smoak, which must have been occasioned by some inward operation of fire; i am apt to think, that the lava, which should naturally have followed this symptom, has broke its way into some deeper cavern, where it is silently brooding future mischief; and i shall be much mistaken if it does not break out a few months hence. tuesday th, no more black smoak, nor any signs of eruption. thus, my lord, i have had the honor of giving your lordship a faithful narrative of my observations during this eruption, which is universally allowed to have been the most violent of this century; and i shall be happy, if it should meet with your approbation, and that of the royal society, if your lordship should think it worthy of being communicated to so respectable a body. i have just sent a present to the british museum of a complete collection of every sort of matter produced by mount vesuvius, which i have been collecting with some pains for these three years past; and it will be a great satisfaction to me, if, by the means of this collection, some of my countrymen, learned in natural history, may be enabled to make some useful discoveries relative to volcanos[ ]. i have also accompanied that collection with a view of a current of lava from mount vesuvius; it is painted with transparent colours, and, when lighted up with lamps behind it, gives a much better idea of vesuvius, than is possible to be given by any other sort of painting. i have the honor to be, my lord, your lordship's most obedient and most humble servant, william hamilton. [illustration: _plate i._ view of the great eruption of vesuvius from portici.] plate i. a. crater of mount vesuvius. b. mouth from whence came the lava of ; and which opened afresh, october , , and produced the conflagration represented in plate ii. c. the mouth which opened at o'clock, october , , whilst i was at the spot marked x; from thence came all the lava represented in plate i. d. the lava. e. mouth from whence the lava flowed at eight o'clock, october , when the eruption began first. f. chapel of saint vito, surrounded with lava. . vesuvius. . mountain of somma. . hermitage, between which and vesuvius there is a deep valley two miles broad. . the fossa grande. . his sicilian majesty's palace at portici. . church of pugliano. . calmaldolese convent, near which is my villa. . saint jorio. . barra. . spot, under which lies herculaneum. [illustration: _plate ii._ view of the great eruption of vesuvius , from torre dell' annunziata.] plate ii. a. crater of vesuvius. b. mouth, from whence came the lava of , and which opened afresh at two o'clock, october , , and caused the conflagration on this side of the mountain. c. mouth which opened at o'clock, october , , whilst i was at the spot x, and which produced all the lava represented in plate i. d. rivulets of lava, which flowed from the crater, and united with the great river e. f. extremities of the lava, about five miles from b. . mountain of somma. . mount vesuvius. . montagna di trecase. . trecase. . oratorio di bosco. . ottaiano. [illustration: _plate iii._ _the ancient crater of mount vesuvius._ _with the gradual increase of the little mountain within the crater._ _the exteriour black line marks each increase & the interiour dotted line shews the state of the little mountain before that increase, so that the dotted line in the drawing of oct .^{th} shews the size of the little mountain july .^{th} the little spot a. marks where the lava came out some days before the great eruption. b. c. d. mark the ancient crater & e. the little mountain the day before the eruption. f. g. is the present crater, & the exteriour black line h. f. g. the present shape of the top of mount vesuvius. since may last the mountain is increased from b. to f. which is near feet._] plate iii. views of the gradual increase of the little mountain within the ancient crater; and of the present shape of mount vesuvius. letter iii. to mathew maty, m. d. secretary to the royal society. villa angelica, near mount vesuvius, october , . sir, i have but very lately received your last obliging letter, of the th of july, with the volume of philosophical transactions. i must beg of you to express my satisfaction at the notice which the royal society hath been pleased to take of my accounts of the two last eruptions of mount vesuvius. since i have been at my villa here, i have enquired of the inhabitants of the mountain, after what they had seen during the last eruption. in my letter to lord morton, i mentioned nothing but what came immediately under my own observation: but as all the peasants here agree in their account of the terrible thunder and lightning, which lasted almost the whole time of the eruption, upon the mountain only; i think it a circumstance worth attending to. besides the lightning, which perfectly resembled the common forked lightning, there were many meteors, like what are vulgarly called _falling stars_. a peasant, in my neighbourhood, lost eight hogs, by the ashes falling into the trough with their food: they grew giddy, and died in a few hours. the last day of the eruption, the ashes, which fell abundantly upon the mountain, were as white almost as snow[ ]; and the old people here assure me, that is a sure symptom of the eruption being at an end. these circumstances, being well attested, i thought worth relating. it would require many years close application, to give a proper and truly philosophical account of the volcanos in the neighbourhood of naples; but i am sure such a history might be given, supported by demonstration, as would destroy every system hitherto given upon this subject. we have here an opportunity of seeing volcanos in all their states. i have been this summer in the island of ischia; it is about eighteen miles round, and its whole basis is lava. the great mountain in it, near as high as vesuvius, formerly called epomeus, and now san nicolo, i am convinced, was thrown up by degrees; and i have no doubt in my own mind, but that the island itself rose out of the sea in the same manner as some of the azores. i am of the same opinion with respect to mount vesuvius, and all the high grounds near naples; as having not yet seen, in any one place, what can be called virgin earth. i had the pleasure of seeing a well sunk, a few days ago, near my villa, which is, as you know, at the foot of vesuvius, and close by the sea-side. at twenty-five feet below the level of the sea, they came to a stratum of lava, and god knows how much deeper they might have still found other lavas. the soil all round the mountain, which is so fertile, consists of stratas of lavas, ashes, pumice, and now-and-then a thin stratum of good earth, which good earth is produced by the surface mouldering, and the rotting of the roots of plants, vines, &c. this is plainly to be seen at pompeii, where they are now digging into the ruins of that ancient city; the houses are covered about ten or fifteen feet, with pumice and fragments of lava, some of which weigh three pounds (which last circumstance i mention, to shew, that, in a great eruption, vesuvius has thrown stones of this weight six miles[ ], which is its distance from pompeii, in a direct line); upon this stratum of pumice, or _rapilli_, as they call them here, is a stratum of excellent mould, about two feet thick, on which grow large trees, and excellent grapes. we have then the solfaterra, which was certainly a volcano, and has ceased erupting, for want of metallic particles, and over-abounding with sulphur. you may trace its lavas into the sea. we have the lago d'averno and the lago d'agnano, both of which were formerly volcanos; and astroni, which still retains its form more than any of these. its crater is walled round, and his sicilian majesty takes the diversion of boar-hunting in this volcano; and neither his majesty nor any one of his court ever dreamt of its former state. we have then that curious mountain, called montagno nuovo, near puzzole, which rose, in one night, out of the lucrine lake; it is about a hundred and fifty feet high, and three miles round. i do not think it more extraordinary, that mount vesuvius, in many ages, should rise above two thousand feet; when this mountain, as is well attested, rose in one night, no longer ago than the year . i have a project, next spring, of passing some days at puzzole, and of dissecting this mountain, taking its measures, and making drawings of its stratas; for, i perceive, it is composed of stratas, like mount vesuvius, but without lavas. as this mountain is so undoubtedly formed intirely from a plain, i should think my project may give light into the formation of many other mountains, that are at present thought to have been original, and are certainly not so, if their strata correspond with those of the montagno nuovo. i should be glad to know whether you think this project of mine will be useful; and, if you do, the result of my observations may be the subject of another letter[ ]. i cannot have a greater pleasure than to employ my leisure hours in what may be of some little use to mankind; and my lot has carried me into a country, which affords an ample field for observation. upon the whole, if i was to establish a system, it would be, that _mountains are produced by volcanos, and not volcanos by mountains_. i fear i have tired you; but the subject of volcanos is so favourite a one with me, that it has led me on i know not how: i shall only add, that vesuvius is quiet at present, though very hot at top, where there is a deposition of boiling sulphur. the lava that ran in the fossa grande during the last eruption, and is at least two hundred feet thick, is not yet cool; a stick, put into its crevices, takes fire immediately. on the sides of the crevices are fine crystalline salts: as they are the pure salts, which exhale from the lava that has no communication with the interiour of the mountain, they may perhaps indicate the composition of the lava. i have done. let me only thank you for the kind offers and expressions in your letter, and for the care you have had in setting off my present to the museum to the best advantage; of which i have been told from many quarters. i am, sir, your most obedient humble servant, w. hamilton. letter iv. to mathew maty, m. d. secretary to the royal society. an account of a journey to mount etna. "artificis naturæ ingens opus aspice, nulla "tu tanta humanis rebus spectacula cernes." p. cornelii severi _Ætna_. naples, oct. , . sir, encouraged by the assurances you give me, in your last obliging letter of the th of june, that any new communication upon the subject of volcano's would be received with satisfaction by the royal society; i venture to send you the following account of my late observations upon mount etna, which you are at liberty to lay before our respectable society, should you think it worth its notice. [see plate iv.] [illustration: _plate iv._ a view of mount Ætna from taormina.] after having examined with much attention the operations of mount vesuvius, during the five years that i have had the honour of residing as his majesty's minister at this court, and after having carefully remarked the nature of the soil for fifteen miles round this capital; i am, in my own mind, well convinced that the whole of it has been formed by explosion. many of the craters, from whence this matter has issued, are still visible; such as the solfaterra near puzzole, the lake of agnano, and near this lake a mountain composed of burnt matter, that has a very large crater surrounded with a wall, to inclose the wild boars and deer, that are kept there for the diversion of his sicilian majesty; it is called astruni: the monte nuovo, thrown up from the bottom of the lucrine lake[ ] in the year , which has likewise its crater; and the lake of averno. the islands of nisida and procida are entirely composed of burnt matter; the island of ischia is likewise composed of lava, pumice, and burnt matter; and there are in that island several visible craters, from one of which, no longer ago than the year , there issued a lava, which ran into the sea, and is still in the same barren state as the modern lavas of vesuvius. after having, i say, been accustomed to these observations, i was well prepared to visit the most ancient, and perhaps the most considerable, volcano that exists; and i had the satisfaction of being thoroughly convinced there, of the formation of very considerable mountains by meer explosion, having seen many such on the sides of etna, as will be related hereafter. on the th of june last, in the afternoon, i left catania, a town situated at the foot of mount etna, or, as it is now called, mon-gibello, in company with lord fortrose and the canonico recupero, an ingenious priest of catania, who is the only person there that is acquainted with the mountain: he is actually employed in writing its natural history; but, i fear, will not be able to compass so great and useful an undertaking, for want of proper encouragement. we passed through the inferior district of the mountain, called by its inhabitants la regione piemontese. it is well watered, exceedingly fertile, and abounding with vines and other fruit trees, where the lava, or, as it is called there, the _sciara_, has had time to soften, and gather soil sufficient for vegetation, which, i am convinced from many observations, unless assisted by art, does not come to pass for many ages[ ], perhaps a thousand years or more; the circuit of this lower region, forming the basis of the great volcano, is upwards of one hundred italian miles. the vines of etna are kept low, quite the reverse of those on the borders of vesuvius; and they produce a stronger wine, but not in so great abundance. the piemontese district is covered with towns, villages, monasteries, &c. and is well peopled, notwithstanding the danger of such a situation. catania, so often destroyed by eruptions of etna, and totally overthrown by an earthquake towards the end of the last century[ ], has been re-built within these fifty years, and is now a considerable town, with at least thirty-five thousand inhabitants. i do not wonder at the seeming security with which these parts are inhabited, having been so long witness to the same near mount vesuvius. the operations of nature are slow: great eruptions do not frequently happen; each flatters himself it will not happen in his time, or, if it should, that his tutelar saint will turn away the destructive lava from his grounds; and indeed the great fertility in the neighbourhoods of volcanos tempts people to inhabit them. in about four hours of gradual ascent, we arrived at a little convent of benedictine monks, called st. nicolo dell' arena, about thirteen miles from catania, and within a mile of the volcano from whence issued the last very great eruption in the year ; a circumstantial account of which was sent to our court by a lord winchelsea, who happened to be then at catania in his way home, from his embassy at constantinople. his lordship's account is curious, and was printed in london soon after; i saw a copy of it at palermo, in the library of the prince torremuzzo[ ]. we slept in the benedictines convent the night of the th, and passed the next morning in observing the ravage made by the abovementioned terrible eruption, over the rich country of the piemontese. the lava burst out of a vineyard within a mile of st. nicolo, and, by frequent explosions of stones and ashes, raised there a mountain, which, as near as i can judge, having ascended it, is not less than half a mile perpendicular in height, and is certainly at least three miles in circumference at its basis. the lava that ran from it, and on which there are as yet no signs of vegetation, is fourteen miles in length, and in many parts six in breadth; it reached catania, and destroyed part of its walls, buried an amphitheatre, an aqueduct, and many other monuments of its ancient grandeur, which till then had resisted the hand of time, and ran a considerable length into the sea, so as to have once formed a beautiful and safe harbour; but it was soon after filled up by a fresh torrent of the same inflamed matter: a circumstance the catanians lament to this day, as they are without a port. there has been no such eruption since, though there are signs of many, more terrible, that have preceded it. for two or three miles round the mountain raised by this eruption, all is barren, and covered with ashes; this ground, as well as the mountain itself, will in time certainly be as fertile as many other mountains in its neighbourhood, that have been likewise formed by explosion. if the dates of these explosions could be ascertained, it would be very curious, and mark the progress of time with respect to the return of vegetation, as the mountains raised by them are in different states; those which i imagine to be the most modern are covered with ashes only; others of an older date, with small plants and herbs; and the most ancient, with the largest timber-trees i ever saw: but i believe the latter are so very ancient, as to be far out of the reach of history. at the foot of the mountain, raised by the eruption of the year , there is a hole, through which, by means of a rope, we descended into several subterraneous caverns, branching out and extending much farther and deeper than we chose to venture; the cold there being excessive, and a violent wind frequently extinguishing some of our torches. these caverns undoubtedly contained the lava that issued forth, and extended, as i said before, quite to catania. there are many of these subterraneous cavities known, on other parts of etna; such as that called by the peasants la baracca vecchia, another la spelonca della palomba (from the wild pigeons building their nests therein), and the cavern thalia, mentioned by boccaccio. some of them are made use of as magazines for snow; the whole island of sicily and malta being supplied with this essential article (in a hot climate) from mount etna. many more would be found, i dare say, if searched for, particularly near and under the craters from whence great lavas have issued, as the immense quantities of such matter we see above ground, must necessarily suppose very great hollows underneath. after having passed the morning of the th in these observations, we proceeded through the second or middle region of etna, called la selvosa, _the woody_, than which nothing can be more beautiful. on every side are mountains, or fragments of mountains, that have been thrown up by various ancient explosions; there are some near as high as mount vesuvius; one in particular (as the canon our guide assured me, having measured it) is little less than one mile in perpendicular height, and five in circumference at its basis. they are all more or less covered, even within their craters, as well as the rich vallies between them, with the largest oak, chesnut, and firr trees, i ever saw any where; and indeed it is from hence chiefly, that his sicilian majesty's dockyards are supplied with timber. as this part of etna was famous for its timber in the time of the tyrants of syracusa, and as it requires the great length of time i have already mentioned before the matter is fit for vegetation, we may conceive the great age of this respectable volcano. the chesnut-trees predominated in the parts through which we passed, and, though of a very great size, are not to be compared to some on another part of the regione selvosa, called carpinetto. i have been told by many, and particularly by our guide, who had measured the largest there, called la castagna cento cavalli, that it is upwards of twenty-eight neapolitan canes in circumference. now as a neapolitan cane is two yards and half a quarter, english measure, you may judge, sir, of the immense size of this famous tree[ ]. it is hollow from age, but there is another near it almost as large and sound. as it would have required a journey of two days to have visited this extraordinary tree, and the weather being already very hot, i did not see it. it is amazing to me, that trees should flourish in so shallow a soil; for they cannot penetrate deep without meeting with a rock of lava; and indeed great part of the roots of the large trees we passed by are above ground, and have acquired, by the impression of the air, a bark like that of their branches. in this part of the mountain, are the finest horned cattle in sicily; we remarked in general, that the horns of the sicilian cattle are near twice the size of any we had ever seen; the cattle themselves are of the common size. we passed by the lava of the last eruption in the year , which has destroyed above four miles square of the beautiful wood abovementioned. the mountain raised by this eruption abounds with sulphur and salts, exactly resembling those of vesuvius; specimens of which i sent some time ago to the late lord morton. in about five hours from the time we had left the convent of st. nicolo dell' arena, we arrived at the borders of the third region, called la netta, or scoperta, _clean_ or _uncovered_, where we found a very sharp air indeed; so that, in the same day, the four seasons of the year were sensibly felt by us, on this mountain; excessive summer heats in the piemontese, spring and autumn temperature in the middle, and extreme cold of winter in the upper region. i could perceive, as we approached the latter, a gradual decrease of vegetation; and from large timber trees we came to the small shrubs and plants of the northern climates: i observed quantities of juniper and tanzey; our guide told us that later in the season there are numberless curious plants here, and that in some parts there are rhubarb and saffron in plenty. in carrera's history of catania, there is a list of all the plants and herbs of etna in alphabetical order. night coming on, we here pitched a tent, and made a good fire, which was very necessary; for without it, and very warm cloathing, we should surely have perished with cold; and at one of the clock in the morning of the th, we pursued our journey towards the great crater. we passed over vallies of snow, that never melts, except there is an eruption of lava from the upper crater, which scarcely ever happens; the great eruptions are usually from the middle region, the inflamed matter finding (as i suppose) its passage through some weak part, long before it can rise to the excessive height of the upper region, the great mouth on the summit only serving as a common chimney to the volcano. in many places the snow is covered with a bed of ashes, thrown out of the crater, and the sun melting it in some parts makes this ground treacherous; but as we had with us, besides our guide, a peasant well accustomed to these vallies, we arrived safe at the foot of the little mountain of ashes that crowns etna, about an hour before the rising of the sun. this mountain is situated in a gently inclining plain of about nine miles in circumference; it is about a quarter of a mile perpendicular in height, very steep, but not quite so steep as vesuvius; it has been thrown up within these twenty-five or thirty years, as many people at catania have told me they remembered when there was only a large chasm or crater, in the midst of the abovementioned plain. till now, the ascent had been so gradual (for the top of etna is not less than thirty miles from catania, from whence the ascent begins) as not to have been the least fatiguing; and if it had not been for the snow, we might have rode upon our mules to the very foot of the little mountain, higher than which the canon our guide had never been: but as i saw that this little mountain was composed in the same manner as the top of vesuvius, which, notwithstanding the smoak issuing from every pore, is solid and firm, i made no scruple of going up to the edge of the crater; and my companions followed. the steep ascent, the keenness of the air, the vapours of the sulphur, and the violence of the wind, which obliged us several times to throw ourselves flat upon our faces to avoid being overturned by it, made this latter part of our expedition rather inconvenient and disagreeable. our guide, by way of comfort, assured us, that there was generally much more wind in the upper region at this time. soon after we had seated ourselves on the highest point of etna, the sun arose, and displayed a scene that indeed passes all description. the horizon lighting up by degrees, we discovered the greatest part of calabria, and the sea on the other side of it; the phare of messina, the lipari islands; stromboli, with its smoaking top, though at above seventy miles distance, seemed to be just under our feet; we saw the whole island of sicily, its rivers, towns, harbours, &c. as if we had been looking on a map. the island of malta is low ground, and there was a haziness in that part of the horizon, so that we could not discern it; our guide assured us, he had seen it distinctly at other times, which i can believe, as in other parts of the horizon, that were not hazy, we saw to a much greater distance; besides, we had a clear view of etna's top from our ship, as we were going into the mouth of the harbour of malta some weeks before; in short, as i have since measured on a good chart, we took in at one view a circle of above nine hundred english miles. the pyramidal shadow of the mountain reached across the whole island, and far into the sea on the other side. i counted from hence forty-four little mountains (little i call them in comparison of their mother etna, though they would appear great any where else) in the middle region on the catania side, and many others on the other side of the mountain, all of a conical form, and each having its crater; many with timber trees flourishing both within and without their craters. the points of those mountains that i imagine to be the most ancient are blunted, and the craters of course more extensive and less deep than those of the mountains formed by explosions of a later date, and which preserve their pyramidal form entire. some have been so far mouldered down by time, as to have no other appearance of a crater than a sort of dimple or hollow on their rounded tops, others with only half or a third part of their cone standing; the parts that are wanting having mouldered down, or perhaps been detached from them by earthquakes, which are here very frequent. all however have been evidently raised by explosion; and i believe, upon examination, many of the whimsical shapes of mountains in other parts of the world would prove to have been occasioned by the same natural operations. i observed that these mountains were generally in lines or ridges; they have mostly a fracture on one side, the same as in the little mountains raised by explosion on the sides of vesuvius, of which there are eight or nine. this fracture is occasioned by the lava's forcing its way out, which operation i have described in my account of the last eruption of vesuvius. whenever i shall meet with a mountain, in any part of the world, whose form is regularly conical, with a hollow crater on its top, and one side broken, i shall be apt to decide such a mountain's having been formed by an eruption; as both on etna and vesuvius the mountains formed by explosion are without exception according to this description. but to return to my narrative. after having feasted our eyes with the glorious prospect above-mentioned (for which, as spartian tells us, the emperor adrian was at the trouble of ascending etna), we looked into the great crater, which, as near as we could judge, is about two miles and a half in circumference; we did not think it safe to go round and measure it, as some parts seemed to be very tender ground. the inside of the crater, which is incrusted with salts and sulphurs like that of vesuvius, is in the form of an inverted hollow cone, and its depth nearly answers to the height of the little mountain that crowns the great volcano. the smoak, issuing abundantly from the sides and bottom, prevented our seeing quite down; but the wind clearing away the smoak from time to time, i saw this inverted cone contracted almost to a point; and, from repeated observations, i dare say, that in all volcanos, the depth of the craters will be found to correspond nearly to the height of the conical mountains of cinders which usually crown them; in short, i look upon the craters as a sort of suspended funnels, under which are vast caverns and abysses. the formation of such conical mountains with their craters are easily accounted for, by the fall of the stones, cinders, and ashes, emitted at the time of an eruption. the smoak of etna, though very sulphureous, did not appear to me so fetid and disagreeable as that of vesuvius; but our guide told me, that its quality varies, as i know that of vesuvius does, according to the quality of the matter then in motion within. the air was so very pure and keen in the whole upper region of etna, and particularly in the most elevated parts of it, that we had a difficulty in respiration, and that, independent of the sulphureous vapour. i brought two barometers and a thermometer with me from naples, intending to have left one with a person at the foot of the mountain, whilst we made our observation with the other, at sun-rising, on the summit; but one barometer was unluckily spoilt at sea, and i could find no one expert enough at catania to repair it: what is extraordinary, i do not recollect having seen a barometer in any part of sicily. at the foot of etna, the th, when we made our first observation, the quicksilver stood at degrees lines; and the th, at the most elevated point of the volcano, it was at degrees lines. the thermometer, on the first observation at the foot of the mountain was at degrees, and on the second at the crater at [ ]. the weather had not changed in any respect, and was equally fine and clear, the th and th. we found it difficult to manage our barometer in the extreme cold and high wind on the top of etna; but, from the most exact observations we could make in our circumstances, the result was as abovementioned. the canon assured me, that the perpendicular height of mount etna is something more than three italian miles, and i verily believe it is so. after having passed at least three hours on the crater, we descended, and went to a rising ground, about a mile distant from the upper mountain we had just left, and saw there some remains of the foundation of an ancient building; it is of brick, and seems to have been ornamented with white marble, many fragments of which are scattered about. it is called the philosopher's tower, and is said to have been inhabited by empedocles. as the ancients used to sacrifice to the celestial gods on the top of etna[ ], it may very well be the ruin of a temple that served for that purpose. from hence we went a little further over the inclined plain abovementioned, and saw the evident marks of a dreadful torrent of hot water, that came out of the great crater at the time of an eruption of lava in the year , and upon which phænomenon the canonico recupero, our guide, has published a dissertation. luckily this torrent did not take its course over the inhabited parts of the mountain; as a like accident on mount vesuvius in swept away some towns and villages in its neighbourhood, with thousands of their inhabitants. the common received opinion is, that these eruptions of water proceed from the volcanos having a communication with the sea; but i rather believe them to proceed merely from depositions of rain water in some of the inward cavities of them. we likewise saw from hence the whole course of ancient lava, the most considerable as to its extent of any known here; it ran into the sea near taormina, which is not less than thirty miles from the crater whence it issued, and is in many parts fifteen miles in breadth. as the lavas of etna are very commonly fifteen and twenty miles in length, six or seven in breadth, and fifty feet or more in depth; you may judge, sir, of the prodigious quantities of matter emitted in a great eruption of this mountain, and of the vast cavities there must necessarily be within its bowels. the most extensive lavas of vesuvius do not exceed seven miles in length. the operations of nature on the one mountain and the other are certainly the same; but on mount etna, all are upon a great scale. as to the nature and quality of their lavas, they are much the same; but i think those of etna rather blacker, and in general more porous, than those of vesuvius. in the parts of etna that we went over, i saw no stratas of pumice stones, which are frequent near vesuvius, and cover the ancient city of pompeii; but our guide told us, that there are such in other parts of the mountain. i saw some stratas of what is called here _tufa_; it is the same that covers herculaneum, and that composes most of the high grounds about naples; it is, upon examination, a mixture of small pumice stones, ashes, and fragments of lava, which is by time hardened into a sort of stone[ ]. in short, i found, with respect to the matter erupted, nothing on mount etna that vesuvius does not produce; and there certainly is a much greater variety in the erupted matter and lavas of the latter, than of the former; both abound with pyrites and crystallizations, or rather vitrifications. the sea shore at the foot of etna, indeed, abounds with amber, of which there is none found at the foot of vesuvius. at present there is a much greater quantity of sulphur and salts on the top of vesuvius than on that of etna; but this circumstance varies according to the degree of fermentation within; and our guide assured me, he had seen greater quantities on etna at other times. in our way back to catania, the canon shewed me a little hill, covered with vines, which belonged to the jesuits, and, as is well attested, was undermined by the lava in the year , and transported half a mile from the place where it stood, without having damaged the vines. in great eruptions of etna, the same sort of lightning, as described in my account of the last eruption of vesuvius, has been frequently seen to issue from the smoak of its great crater. the antients took notice of the same phænomenon; for seneca (lib. ii. nat. quæst.) says,--"Ætna aliquando multo igne abundavit, ingentem vim arenæ urentis effudit, involutus est dies pulvere, populosque subita nox terruit, _illo tempore aiunt plurima fuisse tonitrua et fulmina_." till the year of christ, the chronological accounts of the eruptions of etna are very imperfect: but as the veil of st. agatha was in that year first opposed to check the violence of the torrents of lava, and has ever since been produced at the time of great eruptions; the miracles attributed to its influence, having been carefully recorded by the priests, have at least preserved the dates of such eruptions. the relicks of st. januarius have rendered the same service to the lovers of natural history, by recording the great eruptions of vesuvius. i find, by the dates of the eruptions of etna, that it is as irregular and uncertain in its operations as vesuvius[ ]. the last eruption was in . on our return from messina to naples, we were becalmed three days in the midst of the lipari islands, by which we had an opportunity of seeing that they have all been evidently formed by explosion[ ]; one of them, called vulcano, is in the same state as the solfaterra. stromboli is a volcano, existing in all its force, and, in its form of course, is the most pyramidal of all the lipari islands; we saw it throw up red hot stones from its crater frequently, and some small streams of lava issued from its side, and ran into the sea[ ]. this volcano differs from etna and vesuvius, by its continually emitting fire, and seldom any lava; notwithstanding its continual explosions, this island is inhabited, on one side, by about an hundred families. [illustration: _plate v._ stromboli, one of the lipari islands.] these, as well as i can recollect, are all the observations that i made with respect to volcanos, in may late curious tour of sicily; and i shall be very happy should the communication of them afford you, or any of our countrymen (lovers of natural history) satisfaction or entertainment. i am, sir, with great regard and esteem, your most obedient humble servant, w. hamilton. letter v. to mathew maty, m. d. secretary to the royal society. remarks upon the nature of the soil of naples, and its neighbourhood. "mille miracula movet saciemque mutat locis, et defert montes, subrigit plana, valles extuberat novas, in profundo insulas eregit." seneca, de terra-motu. naples, oct. , . sir, according to your desire, i lose no time in sending you such further remarks as i have been making with some diligence, for six years past, in the compass of twenty miles, or more, round this capital. by accompanying these remarks with a map of the country i describe [plate vi.], and with the specimens of different matters that compose the most remarkable spots of it, i do not doubt but that i shall convince you, as i am myself convinced, that the whole circuit (so far as i have examined) within the boundaries marked in the map is wholly and totally the production of subterraneous fires; and that most probably the sea formerly reached the mountains that lie behind capua and caserta, and are a continuation of the appenines. if i may be allowed to compare small things with great, i imagine the subterraneous fires to have worked in this country, under the bottom of the sea, as moles in a field, throwing up here and there a hillock; and that the matter thrown out of some of these hillocks, formed into settled volcanos, filling up the space between one and the other, has composed this part of the continent, and many of the islands adjoining. from the observations i have made upon mount etna, vesuvius, and its neighbourhood, i dare say, that, after a careful examination, most mountains, that are or have been volcanos, would be found to owe their existence to subterraneous fire; the direct reverse of what i find the commonly received opinion. nature, though varied, is certainly in general uniform in her operations; and i cannot conceive that two such considerable volcanos as etna and vesuvius should have been formed otherwise than every other considerable volcano of the known world. i do not wonder that so little progress has been made in the improvement of natural history, and particularly in that branch of it which regards the theory of earth; nature acts slowly, it is difficult to catch her in the fact. those who have made this subject their study have, without scruple, undertaken at once to write the natural history of a whole province, or of an entire continent; not reflecting, that the longest life of man scarcely affords him time to give a perfect one of the smallest insect. i am sensible of what i undertake in giving you, sir, even a very imperfect account of the nature of the soil of a little more than twenty miles round naples: yet i flatter myself that my remarks, such as they are, may be of some use to any one hereafter, who may have leisure and inclination to follow them up. the kingdom of the two sicilies offers certainly the fairest field for observations of this kind, of any in the whole world; here are volcanos existing in their full force, some on their decline, and others totally extinct. to begin with some degree of order, which is really difficult in the variety of matter that occurs to my mind, i will first mention the basis on which i found all my conjectures. it is the nature of the soil that covers the antient towns of herculaneum and pompeii, and the interior and exterior form of the new mountain, near puzzole, with the sort of materials of which it is composed. it cannot be denied, that herculaneum and pompeii stood once above ground; though now, the former is in no part less than seventy feet, and in some parts one hundred and twelve feet, below the present surface of the earth; and the latter is buried ten or twelve feet deep, more or less. as we know from the very accurate account given by pliny the younger to tacitus, and from the accounts of other contemporary authors, that these towns were buried by an eruption of mount vesuvius in the time of titus; it must be allowed, that whatever matter lies between these cities and the present surface of the earth over them, must have been produced since the year of the christian æra, the date of that formidable eruption. pompeii, which is situated at a much greater distance from the volcano than herculaneum, has felt the effects of a single eruption only; it is covered with white pumice stones, mixed with fragments of lava and burnt matter, large and small: the pumice is very light; but i have found some of the fragments of lava and cinders there, weighing eight pounds. i have often wondered, that such weighty bodies could have been carried to such a distance (for pompeii cannot be less than five miles, in a strait line, from the mouth of vesuvius). every observation confirms the fall of this horrid shower over the unfortunate city of pompeii, and that few of its inhabitants had dared to venture out of their houses; for in many of those which have been already cleared, skeletons have been found, some with gold rings, ear rings, and bracelets. i have been present at the discovery of several human skeletons myself; and under a vaulted arch, about two years ago, at pompeii, i saw the bones of a man and a horse taken up, with the fragments of the horse's furniture, which had been ornamented with false gems set in bronze. the skulls of some of the skeletons found in the streets had been evidently fractured by the fall of the stones. his sicilian majesty's excavations are confined to this spot at present; and the curious in antiquity may expect hereafter, from so rich a mine, ample matter for their dissertations: but i will confine myself to such observations only as relate to my present subject. over the stratum of pumice and burnt matter that covers pompeii, there is a stratum of good mould, of the thickness of about two feet and more in some parts, in which vines flourish, except in some particular spots of this vineyard, where they are subject to be blasted by a foul vapour, or _mofete_, as it is called here, that rises from beneath the burnt matter. the abovementioned shower of pumice stones, according to my observations, extended beyond castel-a-mare (near which spot the ancient town of stabia also lies buried under them) and covered a tract of country not less than thirty miles in circumference. it was at stabia that pliny the elder lost his life, and this shower of pumice stones is well described in the younger pliny's letter. little of the matter that has issued from vesuvius since that time, has reached these parts: but i must observe, that the pavement of the streets of pompeii is of lava; nay, under the foundation of the town, there is a deep stratum of lava and burnt matter. these circumstances, with many others that will be related hereafter, prove, beyond a doubt, that there have been eruptions of vesuvius previous to that of the year , which is the first recorded by history. the growth of soil by time is easily accounted for; and who, that has visited ruins of ancient edifices, has not often seen a flourishing shrub, in a good soil, upon the top of an old wall? i have remarked many such on the most considerable ruins at rome and elsewhere. but from the soil which has grown over the barren pumice that covers pompeii, i was enabled to make a curious observation. upon examining the cuts and hollow ways made by currents of water in the neighbourhood of vesuvius and of other volcanos, i had remarked that there lay frequently a stratum of rich soil, of more or less depth, between the matter produced by the explosion of succeeding eruptions[ ]; and i was naturally led to think, that such a stratum had grown in the same manner as the one abovementioned over the pumice of pompeii. where the stratum of good soil was thick, it was evident to me that many years had elapsed between one eruption and that which succeeded it. i do not pretend to say, that a just estimate can be formed of the great age of volcanos from this observation; but some sort of calculation might be made: for instance, should an explosion of pumice cover again the spot under which pompeii is buried, the stratum of rich soil abovementioned would certainly lie between two beds of pumice; and if a like accident had happened a thousand years ago, the stratum of rich soil would as certainly have wanted much of its present thickness, as the rotting of vegetables, manure, &c. is ever increasing a cultivated soil. whenever i find then a succession of different strata of pumice and burnt matter, like that which covers pompeii, intermixed with strata of rich soil, of greater or less depth, i hope i may be allowed reasonably to conclude, that the whole has been the production of a long series of eruptions, occasioned by subterraneous fire. by the size and weight of the pumice, and fragments of burnt erupted matter in these strata, it is easy to trace them up to their source, which i have done more than once in the neighbourhood of puzzole, where explosions have been frequent. the gradual decrease in the size and quantity of the erupted matter in the stratum abovementioned, from pompeii to castle-a-mare, is very visible: at pompeii, as i said before, i have found them of eight pounds weight, when at castle-a-mare the largest do not weigh an ounce. the matter which covers the ancient town of herculaneum is not the produce of one eruption only; for there are evident marks that the matter of six eruptions has taken its course over that which lies immediately above the town, and was the cause of its destruction. these strata are either of lava or burnt matter, with veins of good soil between them. the stratum of erupted matter that immediately covers the town, and with which the theatre and most of the houses were filled, is not of that foul vitrified matter, called lava, but of a sort of soft stone, composed of pumice, ashes, and burnt matter. it is exactly of the same nature with what is called here the naples stone; the italians distinguish it by the name of _tufa_, and it is in general use for building. its colour is usually that of our free stone, but sometimes tinged with grey, green, and yellow; and the pumice stones, with which it ever abounds, are sometimes large, and sometimes small: it varies likewise in its degree of solidity. the chief article in the composition of _tufa_ seems to me to be, that fine burnt material, which is called _puzzolane_, whose binding quality and utility by way of cement are mentioned by vitruvius[ ], and which is to be met with only in countries that have been subject to subterraneous fires. it is, i believe, a sort of lime prepared by nature. this, mixed with water, great or small pumice stones, fragments of lava, and burnt matter, may naturally be supposed to harden into a stone of this kind[ ]; and, as water frequently attends eruptions of fire, as will be seen in the accounts i shall give of the formation of the new mountain near puzzole, i am convinced the first matter that issued from vesuvius, and covered herculaneum, was in the state of liquid mud. a circumstance strongly favouring my opinion is, that, about two years ago, i saw the head of an antique statue dug out of this matter within the theatre of herculaneum; the impression of its face remains to this day in the _tufa_, and might serve as a mould for a cast in plaister of paris, being as perfect as any mould i ever saw. as much may be inferred from the exact resemblance of this matter, or _tufa_, which immediately covers herculaneum, to all the _tufas_ of which the high grounds of naples and its neighbourhood are composed. i detached a piece of it sticking to, and incorporated with, the painted stucco of the inside of the theatre of herculaneum, and shall send it for your inspection[ ]. it is very different, as you will see, from the vitrified matter called lava, by which it has been generally thought that herculaneum was destroyed. the village of resina and some villas stand at present above this unfortunate town. to account for the very great difference of the matters that cover herculaneum and pompeii, i have often thought that, in the eruption of , the mountain must have been open in more than one place. a passage in pliny's letter to tacitus seems to say as much: "interim è vesuvio monte pluribus locis latissimæ flammæ, atque incendia relucebant, quorum fulgor et claritas tenebras noctis pellebat:" so that very probably the matter that covers pompeii proceeded from a mouth, or crater, much nearer to it than is the great mouth of the volcano, from whence came the matter that covers herculaneum. this matter might nevertheless be said to have proceeded from vesuvius, just as the eruption in the year , which was quite independent of the great crater (being four miles from it), is properly called an eruption of vesuvius. in the beginning of eruptions, volcanos frequently throw up water mixed with the ashes. vesuvius did so in the eruption of , according to the testimony of many contemporary writers. the same circumstance happened in , according to the account of ignazzio sorrentino, who, by his history of mount vesuvius, printed at naples in , has shewn himself to have been a very accurate observer of the phænomena of the volcano, for many years that he lived at torre del greco, situated at the foot of it. at the beginning of the formation of the new mountain, near puzzole, water was mixed with the ashes thrown up, as will be seen in two very curious and particular accounts of the formation of that mountain, which i shall have the pleasure of communicating to you presently; and in , etna threw up a quantity of water in the beginning of an eruption, as is mentioned in the letter i sent you last year upon the subject of that magnificent volcano[ ]. ulloa likewise mentions this circumstance of water attending the eruptions of volcanos in america. whenever therefore i find a _tufa_ composed exactly like that which immediately covers herculaneum, and undoubtedly proceeded from vesuvius, i conclude such a _tufa_ to have been produced by water mixing with the erupted matter at the time of an explosion occasioned by subterraneous fire; and this observation, i believe, will be of more use than any other, in pointing out those parts of the present _terra firma_, that have been formed by explosion. i am convinced, it has often happened that subterraneous fires and exhalations, after having been pent up and confined for some time, and been the cause of earthquakes, have forced their passage, and in venting themselves formed mountains of the matter that confined them, as you will see was the case near puzzole in the year , and by evident signs has been so before, in many parts of the neighbourhood of puzzole; without creating a regular volcano. the materials of such mountains will have but little appearance of having been produced by fire, to any one unaccustomed to make observations upon the different nature of volcanos. if it were allowed to make a comparison between the earth and a human body, one might consider a country replete with combustibles occasioning explosions (which is surely the case here) to be like a body full of humours. when these humours concentre in one part, and form a great tumour out of which they are discharged freely, the body is less agitated; but when, by any accident, the humours are checked, and do not find free passage through their usual channel, the body is agitated, and tumours appear in other parts of that body, but soon after the humours return again to their former channel. in a similar manner one may conceive vesuvius to be the present great channel, through which nature discharges some of the foul humours of the earth: when these humours are checked by any accident or stoppage in this channel for any considerable time, earthquakes will be frequent in its neighbourhood, and explosions may be apprehended even at some distance from it. this was the case in the year , vesuvius having been quiet for near years. there was no eruption from its great crater, from the year to the great eruption of , and the top of the mountain began to lose all signs of fire. as it is not foreign to my purpose, and will serve to shew how greatly they are mistaken, who place the seat of the fire in the centre, or towards the top, of a volcano; i will give you a curious description of the state of the crater of vesuvius, after having been free from eruption years, as related by bracini, who descended into it not long before the eruption of : "the crater was five miles in circumference, and about a thousand paces deep; its sides were covered with brush wood, and at the bottom there was a plain on which cattle grazed. in the woody parts, boars frequently harboured; in the midst of the plain, within the crater, was a narrow passage, through which, by a winding path, you could descend about a mile amongst rocks and stones, till you came to another more spacious plain covered with ashes: in this plain were three little pools, placed in a triangular form, one towards the east, of hot water, corrosive and bitter beyond measure; another towards the west, of water salter than that of the sea; the third of hot water, that had no particular taste." the great increase of the cone of vesuvius, from that time to this, naturally induces one to conclude, that the whole of the cone was raised in the like manner; and that the part of vesuvius, called somma, which is now considered as a distinct mountain from it, was composed in the same manner. this may plainly be perceived, by examining its interior and exterior form, and the strata of lava and burnt matter of which it is composed. the ancients, in describing vesuvius, never mention two mountains. strabo, dio, vitruvius, all agree, that vesuvius, in their time, shewed signs of having formerly erupted[ ], and the first compares the crater on its top to an amphitheatre. the mountain now called somma was, i believe, that which the ancients called vesuvius: its outside form is conical; its inside, instead of an amphitheatre, is now like a great theatre. i suppose the eruption in pliny's time to have thrown down that part of the cone next the sea, which would naturally have left it in its present state; and that the conical mountain, or existing vesuvius, has been raised by the succeeding eruptions: all my observations confirm this opinion. i have seen antient lavas in the plain on the other side of somma, which could never have proceeded from the present vesuvius. serao, a celebrated physician now living at naples, in the introduction of his account of the eruption of vesuvius in (in which account many of the phænomena of the volcano are recorded and very well accounted for), says, that at the convent of dominican fryars, called the madona del arco, some years ago, in sinking a well, at a hundred feet depth, a lava was discovered, and soon after another; so that, in less than three hundred feet depth, the lavas of four eruptions were found. from the situation of this convent, it is clear beyond a doubt, that these lavas proceeded from the mountain called somma, as they are quite out of the reach of the existing volcano. from these circumstances, and from repeated observations i have made in the neighbourhood of vesuvius, i am sure that no virgin soil is to be found there, and that all is composed of different strata of erupted matter, even to a great depth below the level of the sea. in short, i have not any doubt in my own mind, but that this volcano took its rise from the bottom of the sea; and as the whole plain between vesuvius and the mountains behind caserta, which is the best part of the campagna felice, is (under its good soil) composed of burnt matter, i imagine the sea to have washed the feet of those mountains, until the subterraneous fires began to operate, at a period certainly of a most remote antiquity. the soil of the campagna felice is very fertile; i saw the earth opened in many places last year in the midst of that plain, when they were seeking for materials to mend the road from naples to caserta. the stratum of good soil was in general four or five feet thick; under which was a deep stratum of cinders, pumice, fragments of lava, and such burnt matter as abounds near vesuvius and all volcanos. the mountains at the back of caserta are mostly of a sort of lime-stone, and very different from those formed by fire; though signior van vitelli, the celebrated architect, has assured me, that, in the cutting of the famous aqueduct of caserta through these mountains, he met with some soils, that had been evidently formed by subterraneous fire. the high grounds, which extend from castel-a-mare, to the point of minerva towards the island of caprea, and from the promontory that divides the bay of naples from that of salerno, are of lime-stone. the plain of sorrento, that is bounded by these high grounds, beginning at the village of vico, and ending at that of massa, is wholly composed of the same sort of _tufa_ as that about naples, except that the cinders or pumice stones intermixed in it are larger than in the naples _tufa_. i conceive then that there has been an explosion in this spot from the bottom of the sea. this plain, as i have remarked to be the case with all soils produced by subterraneous fire, is extremely fertile; whilst the ground about it, being of another nature, is not so. the island of caprea does not shew any signs of having been formed by subterraneous fire; but is of the same nature as the high grounds last mentioned, from which it has been probably detached by earthquakes, or the violence of the waves. rovigliano, an island, or rather a rock, in the bay of castel-a-mare, is likewise of lime-stone, and seems to have belonged to the original mountains in its neighbourhood: in some of these mountains there are also petrified fish and fossil shells, which i never have found in the mountains which i suppose to have been formed by explosion[ ]. you have now, sir, before you the nature of the soil, from caprea to naples. the soil on which this great metropolis stands has been evidently produced by explosions, some of which seem to have been upon the very spot on which this city is built; all the high grounds round naples, pausilipo, puzzole, baïa, misenum, the islands of procita and ischia, appear to have been raised by explosion. you can trace still in many of these heights the conical shape that was naturally given them at first, and even the craters out of which the matter issued, though to be sure others of these heights have suffered such changes by the hand of time, that you can only conjecture that they were raised in the like manner, by their composition being exactly the same as that of those mountains which still retain their conical form and craters entire. a _tufa_, exactly resembling the specimen i took from the inside of the theatre of herculaneum, layers of pumice intermixed with layers of good soil, just like those over pompeii, and lavas like those of vesuvius, compose the whole soil of the country that remains to be described. the famous grotto anciently cut through the mountain of pausilipo, to make a road from naples to puzzole, gives you an opportunity of seeing that the whole of that mountain is _tufa_. the first evident crater you meet with, after you have passed the grotto of pausilipo, is now the lake of agnano; a small remain of the subterraneous fire (which must probably have made the bason for the lake, and raised the high grounds which form a sort of amphitheatre round it) serves to heat rooms, which the neapolitans make great use of in summer, for carrying off diverse disorders, by a strong perspiration. this place is called the sudatorio di san germano; near the present bagnios, which are but poor little hovels, there are the ruins of a magnificent ancient bath. about an hundred paces from hence is the grotto del cane; i shall only mention, as a further proof of the probability that the lake of agnano was a volcano, that vapours of a pernicious quality, as that in the grotto del cane, are frequently met with in the neighbourhood of etna and vesuvius, particularly at the time of, before, and after, great eruptions. the noxious vapour having continued in the same force constantly so many ages, as it has done in the grotto del cane (for pliny mentions this grotto[ ]), is indeed a circumstance in which it differs from the vapours near vesuvius and etna, which are not constant. the cone forming the outside of this supposed volcano is still perfect in many parts. opposite to the grotto del cane, and immediately joining to the lake, rises the mountain called astruni, which, having, as i imagine, been thrown up by an explosion of a much later date, retains the conical shape and every symptom of a volcano in much greater perfection than that i have been describing. the crater of astruni is surrounded with a wall, to confine boars and deers (this volcano having been for many years converted to a royal chace). it may be about six miles or more in circumference: in the plain at the bottom of the crater are two lakes; and in some books there is mention made of a hot spring, which i never have been able to find. there are many huge rocks of lava within the crater of astruni, and some i have met with also in that of agnano; the cones of both these supposed volcanos are composed of _tufa_ and strata of loose pumice, fragments of lava and other burnt matter, exactly resembling the strata of vesuvius. bartholomeus fatius, who wrote of the actions of king alphonso the first (before the new mountain had been formed near puzzole), conjectured that astruni had been a volcano. these are his words: "locus neapoli quatuor millia passuum proximus, quem vulgo listrones vocant, nos unum è phlegræis campis ab ardore nuncupandum putamus." there is no entrance into the crater of either astruni or agnano, except one, evidently made by art, and they both exactly correspond with strabo's description of avernus; the same may be said of the solfaterra and the monte gauro, or barbaro as it is sometimes called, which i shall describe presently. near astruni and towards the sea rises the solfaterra, which not only retains its cone and crater, but much of its former heat. in the plain within the crater, smoak issues from many parts, as also from its sides; here, by means of stones and tiles heaped over the crevices through which the smoak passes, they collect in an aukward manner what they call _sale armoniaco_; and from the sand of the plain they extract sulphur and alum. this spot, well attended to, might certainly produce a good revenue, whereas i doubt if they have hitherto ever cleared _l._ a year by it. the hollow sound produced by throwing a heavy stone on the plain of the crater of the solfaterra seems to indicate, that it is supported by a sort of arched natural vault; and one is induced to think that there is a pool of water beneath this vault (which boils by the heat of a subterraneous fire still deeper), by the very moist steam that issues from the cracks in the plain of the solfaterra, which, like that of boiling water, runs off a sword or knife, presented to it, in great drops. on the outside, and at the foot of the cone of the solfaterra, towards the lake of agnano, water rushes out of the rocks, so hot, as to raise the quicksilver in fahrenheit's thermometer to the degree of boiling water[ ], a fact of which i was myself an eye-witness. this place, well worthy the observation of the curious, has been taken little notice of; it is called the _pisciarelli_. the common people of naples have great faith in the efficacy of this water; and make much use of it in all cutaneous disorders, as well as for another disorder that prevails here. it seems to be impregnated chiefly with sulphur and alum. when you approach your ear to the rocks of the pisciarelli, from whence this water ouzes, you hear a horrid boiling noise, which seems to proceed from the huge cauldron, that may be supposed to be under the plain of the solfaterra. on the other side of the solfaterra, next the sea, there is a rock, which has communicated with the sea, till part of it was cut away to make the road to puzzole; this was undoubtedly a considerable lava, that ran from the solfaterra when it was an active volcano. under this rock of lava, which is more than seventy feet high, there is a stratum of pumice and ashes. this ancient lava is about a quarter of a mile broad; you meet with it abruptly before you come in sight of puzzole, and it finishes as abruptly within about an hundred paces of the town. i have often thought that many quarries of stone, upon examination, would be found to owe their origin to the same cause, though time may have effaced all signs of the volcano from whence they proceeded. except this rock, which is evidently lava and full of vitrifications like that of vesuvius, all the rocks upon the coast of baïa are of _tufa_. i have observed in the lava of vesuvius and etna, as in this, that the bottom, as well as the surface of it, was rough and porous, like the cinders or scoriæ from an iron foundery; and that for about a foot from the surface and from the bottom, they were not near so solid and compact as towards the centre; which must undoubtedly proceed from the impression of the air upon the vitrified matter whilst in fusion. i mention this circumstance, as it may serve to point out true lavas with more certainty. the ancient name of the solfaterra was, _forum vulcani_; a strong proof of its origin from subterraneous fire. the degree of heat, that the solfaterra has preserved for so many ages, seems to have calcined the stones upon its cone, and in its crater, as they are very white, and crumble easily in the hottest parts. we come next to the new mountain near puzzole, which, being of so very late a formation, preserves its conical shape entire, and produces as yet but a very slender vegetation. it has a crater almost as deep as the cone is high, which may be near a quarter of a mile perpendicular, and is in shape a regular inverted cone. at the basis of this new mountain (which is more than three miles in circumference), the sand upon the sea shore, and even that which is washed by the sea itself, is burning hot for above the space of an hundred yards; if you take up a handful of the sand below water, you are obliged to get rid of it directly, on account of its intense heat. i had been long very desirous of meeting with a good account of the formation of this new mountain, because, proving this mountain to have been raised by mere explosion in a plain, would prove at the same time, that all the neighbouring mountains, which are composed of the same materials, and have exactly or in part the same form, were raised in the like manner; and that the seat of fire, the cause of these explosions, lies deep; which i have every reason to think. fortunately, i lately found two very good accounts of the phænomena that attended the explosion, which formed the new mountain, published a few months after the event. as i think them very curious, and greatly to my purpose, and as they are rare, i will give you a literal translation of such extracts as relate to the formation of the monte nuovo. they are bound in one volume[ ]. the title of the first is, _dell incendio di pozzuolo, marco antonio delli falconi all illustrissima signiora marchesa della padula nel mdxxxviii_. at the head of the second is, _ragionamento del terremoto, del nuovo monte, del aprimento di terra in pozzuolo nell' anno , é della significatione d'essi. per piero giacomo da toledo_; and at the end of the book, _stampata in nap. per giovanni sulztbach alemano, a di genaro , con gratia, é privilegio_. "first then (says marco antonio delli falconi), will i relate simply and exactly the operations of nature, of which i was either myself an eye-witness, or as they were related to me by those who had been witnesses of them. it is now two years that there have been frequent earthquakes at pozzuolo, at naples, and the neighbouring parts; on the day and in the night before the appearance of this eruption, above twenty shocks great and small were felt at the abovementioned places. the eruption made its appearance the th of september , the feast of st. michael the angel; it was on a sunday, about an hour in the night; and, as i have been informed, they began to see on that spot, between the hot baths or sweating rooms, and trepergule, flames of fire, which first made their appearance at the baths, then extended towards trepergule, and fixing in the little valley that lies between the monte barbaro and the hillock called del pericolo (which was the road to the lake of avernus and the baths), in a short time the fire increased to such a degree, that it burst open the earth in this place, and threw up so great a quantity of ashes and pumice stones mixed with water, as covered the whole country; and in naples a shower of these ashes and water fell a great part of the night. the next morning, which was monday, and the last of the month, the poor inhabitants of pozzuolo, struck with so horrible a sight, quitted their habitations, covered with that muddy and black shower, which continued in that country the whole day, flying death, but with faces painted with its colours; some with their children in their arms, some with sacks full of their goods; others leading an ass, loaded with their frightened family, towards naples; others carrying quantities of birds of various sorts, that had fallen dead at the time the eruption began; others again with fish which they had found, and were to be met with in plenty upon the shore, the sea having been at that time considerably dried up. don pedro di toledo, viceroy of the kingdom, with many gentlemen, went to see so wonderful an appearance; i also, having met with the most honourable and incomparable gentleman, signior fabritio moramaldo, on the road, went and saw the eruption and the many wonderful effects of it. the sea towards baïa had retired a considerable way; though, from the quantity of ashes and broken pumice stones thrown up by the eruption, it appeared almost totally dry. i saw likewise two springs in those lately-discovered ruins, one before the house that was the queen's, of hot and salt water; the other of fresh and cold water, on the shore, about paces nearer to the eruption: some say, that, still nearer to the spot where the eruption happened, a stream of fresh water issued forth like a little river. turning towards the place of the eruption, you saw mountains of smoak, part of which was very black and part very white, rise up to a great height; and in the midst of the smoak, at times, deep-coloured flames burst forth with huge stones and ashes, and you heard a noise like the discharge of a number of great artillery. it appeared to me as if typheus and enceladus from ischia and etna with innumerable giants, or those from the campi phlegrei (which, according to the opinions of some, were situated in this neighbourhood), were come to wage war again with jupiter. the natural historians may perhaps reasonably say, that the wise poets meant no more by giants, than exhalations, shut up in the bowels of the earth, which, not finding a free passage, open one by their own force and impulse, and form mountains, as those which occasioned this eruption have been seen to do; and methought i saw those torrents of burning smoak that pindar describes in an eruption of etna, now called mon gibello, in sicily; in imitation of which, as some say, virgil wrote these lines: "ipse sed horrificis juxta tonat Ætna ruinis, &c. "after the stones and ashes with clouds of thick smoak had been sent up, by the impulse of the fire and windy exhalation (as you see in a great cauldron that boils), into the middle region of the air, overcome by their own natural weight, when from distance the strength they had received from impulse was spent, rejected likewise by the cold and unfriendly region, you saw them fall thick, and, by degrees, the condensed smoak clear away, raining ashes with water and stones of different sizes, according to the distance from the place: then, by degrees, with the same noise and smoak, it threw out stones and ashes again, and so on by fits. this continued two days and nights, when the smoak and force of the fire began to abate. the fourth day, which was thursday, at o'clock, there was so great an eruption, that, as i was in the gulph of puzzole, coming from ischia, and not far from misenum, i saw, in a short time, many columns of smoak shoot up, with the most terrible noise i ever heard, and, bending over the sea, came near our boat, which was four miles or more from the place of their birth; and the quantity of ashes, stones, and smoak, seemed as if they would cover the whole earth and sea. stones, great and small, and ashes more or less, according to the impulse of the fire and exhalations, began to fall, so that a great part of this country was covered with ashes; and many, that have seen it, say, they reached the vale of diana, and some parts of calabria, which are more than miles from pozzuolo. the friday and saturday nothing but a little smoak appeared; so that many, taking courage, went upon the spot, and say, that with the stones and ashes thrown up, a mountain has been formed in that valley, not less than three miles in circumference, and almost as high as the monte barbaro, which is near it, covering the canettaria, the castle of trepergule, all those buildings and the greatest part of the baths that were about them; extending south towards the sea, north as far as the lake of avernus, west to the sudatory, and joining east to the foot of the monte barbaro; so that this place has changed its form and face in such a manner as not to be known again: a thing almost incredible, to those who have not seen it, that in so short a time so considerable a mountain could have been formed. on its summit there is a mouth in the form of a cup, which may be a quarter of a mile in circumference, though some say it is as large as our market-place at naples, from which there issues a constant smoak; and though i have seen it only at a distance, it appears very great. the sunday following, which was the th of october, many people going to see this phænomenon, and some having ascended half the mountain, others more, about o'clock there happened so sudden and horrid an eruption, with so great a smoak, that many of these people were stifled, some of which could never be found. i have been told, that the number of the dead or lost amounted to twenty-four. from that time to this, nothing remarkable happened; it seems as if the eruption returned periodically, like the ague or gout. i believe henceforward it will not have such force, though the eruption of the sunday was accompanied with showers of ashes and water, which fell at naples, and were seen to extend as far as the mountain of somma, called vesuvius by the ancients; and, as i have often remarked, the clouds of smoak proceeding from the eruption moved in a direct line towards that mountain, as if these places had a correspondence and connection one with the other. in the night, many beams and columns of fire were seen to proceed from this eruption, and some like flashes of lightning[ ]. we have then, many circumstances for our observation, the earthquakes, the eruption, the drying up of the sea, the quantity of dead fish and birds, the birth of springs, the shower of ashes with water and without water, the innumerable trees in that whole country, as far as the grotto of lucullus, torn from their roots, thrown down, and covered with ashes, that it gave one pain to see them: and as all these effects were produced by the same cause that produces earthquakes; let us first enquire how earthquakes are produced, and from thence we may easily comprehend the cause of the abovementioned events." then follows a dissertation on earthquakes, and some curious conjectures relative to the phænomena which attended this eruption, clearly and well expressed, considering, as the author himself apologizes, that at that time the italian language had been little employed on such subjects. the account of the formation of the monte nuovo, by pietro giacomo di toledo, is given in a dialogue between the feigned personages of peregrino and svessano; the former of which says, "it is now two years that this province of campagna has been afflicted with earthquakes, the country about pozzuolo much more so than any other parts; but the th and the th of the month of september last, the earthquakes did not cease day or night, in the abovementioned city of pozzuolo; that plain, which lies between the lake of averno, the monte barbaro, and the sea, was raised a little, and many cracks were made in it, from some of which issued water; and at the same time the sea, which was very near the plain, dried up about two hundred paces, so that the fish were left on the sand, a prey to the inhabitants of pozzuolo. at last, on the th of the said month, about two hours in the night, the earth opened near the lake, and discovered a horrid mouth, from which were vomited furiously, smoak, fire, stones, and mud composed of ashes; making, at the time of its opening, a noise like very loud thunder: the fire, that issued from this mouth, went towards the walls of the unfortunate city; the smoak was partly black and partly white; the black was darker than darkness itself, and the white was like the whitest cotton: these smoaks, rising in the air, seemed as if they would touch the vault of heaven; the stones that followed were, by the devouring flames, converted to pumice, the size of which (of some i say) were much larger than an ox. the stones went about as high as a cross-bow can carry, and then fell down, sometimes on the edge, and sometimes into the mouth itself. it is very true that many of them in going up could not be seen, on account of the dark smoak; but, when they returned from the smoaky heat, they shewed plainly where they had been, by their strong smell of fetid sulphur, just like stones that have been thrown out of a mortar, and have passed through the smoak of inflamed gunpowder. the mud was of the colour of ashes, and at first very liquid, then by degrees less so; and in such quantities, that in less than twelve hours, with the help of the abovementioned stones, a mountain was raised of a thousand paces in height. not only pozzuolo and the neighbouring country was full of this mud, but the city of naples also, the beauty of whose palaces were, in a great measure, spoiled by it. the ashes were carried as far as calabria by the force of the winds, burning up in their passage the grass and high trees, many of which were borne down by the weight of them. an infinity of birds also, and numberless animals of various kinds, covered with this sulphureous mud, gave themselves up a prey to man. now this eruption lasted two nights and two days without intermission, though, it is true, not always with the same force, but more or less: when it was at its greatest height, even at naples you heard a noise or thundering like heavy artillery when two armies are engaged. the third day the eruption ceased, so that the mountain made its appearance uncovered, to the no small astonishment of every one who saw it. on this day, when i went up with many people to the top of this mountain; i saw down into its mouth, which was a round concavity of about a quarter of a mile in circumference, in the middle of which the stones that had fallen were boiling up, just as in a great cauldron of water that boils on the fire. the fourth day it began to throw up again, and the seventh much more, but still with less violence than the first night; it was at this time that many people, who were unfortunately on the mountain, were either suddenly covered with ashes, smothered with smoak, or, knocked down by stones, burnt by the flame, and left dead on the spot. the smoak continues to this day[ ], and you often see in the night-time fire in the midst of it. finally, to complete the history of this new and unforeseen event, in many parts of the new-made mountain, sulphur begins to be generated." giacomo di toledo, towards the end of his dissertation upon the phænomena attending this eruption, says, that the lake of avernus had a communication with the sea, before the time of the eruption; and that he apprehended that the air of puzzole might come to be affected in summer time, by the vapours from the stagnated waters of the lake; which is actually the case. you have, sir, from these accounts, an instance of a mountain, of a considerable height and dimensions, formed in a plain, by mere explosion, in the space of forty-eight hours. the earthquakes having been sensibly felt at a great distance from the spot where the opening was made, proves clearly, that the subterraneous fire was at a great depth below the surface of the plain; it is as clear that those earthquakes, and the explosion, proceeded from the same cause, the former having ceased upon the appearance of the latter. does not this circumstance evidently contradict the system of m. buffon, and of all the natural historians, who have placed the seat of the fire of volcanos towards the center, or near the summit of the mountains, which they suppose to furnish the matter emitted? did the matter which proceeds from a volcano in an eruption come from so inconsiderable a depth as they imagine, that part of the mountain situated above their supposed seat of the fire must necessarily be destroyed, or dissipated in a very short time: on the contrary, an eruption usually adds to the height and bulk of a volcano; and who, that has had an opportunity of making observations on volcanos, does not know, that the matter they have emitted for many ages, in lavas, ashes, smoak, &c. could it be collected together, would more than suffice to form three such mountains as the simple cone or mountain of the existing volcano? with respect to vesuvius, this could be plainly proved; and i refer to my letter upon the subject of etna, to shew the quantity of matter thrown up in one single eruption, by that terrible volcano. another proof, that the real seat of the fire of volcanos lies even greatly below the general level of the country whence the mountain springs, is, that was it only at an inconsiderable depth below the basis of the mountain, the quantity of matter thrown up would soon leave so great a void immediately under it, that the mountain itself must undoubtedly sink and disappear after a few eruptions. in the above accounts of the formation of the new mountain, we are told that the matter first thrown up, was mud composed of water and ashes, mixed with pumice stones and other burnt matter: on the road leading from puzzole to cuma, part of the cone of this mountain has been cut away, to widen the road. i have there seen that its composition is a _tufa_ intermixed with pumice, some of which are really of the size of an ox, as mentioned in toledo's account, and exactly of the same nature as the _tufa_ of which every other high ground in its neighbourhood is composed; similar also to that which covers herculaneum. according to the above accounts, after the muddy shower ceased, it rained dry ashes: this circumstance will account for the strata of loose pumice and ashes, that are generally upon the surface of all the _tufas_ in this country, and which were most probably thrown up in the same manner. at the first opening of the earth, in the plain near puzzole, both accounts say, that springs of water burst forth; this water, mixing with the ashes, certainly occasioned the muddy shower; when the springs were exhausted, there must naturally have ensued a shower of dry ashes and pumice, of which we have been likewise assured. i own, i was greatly pleased at being in this manner enabled to account so well for the formation of these _tufa_ stones and the veins of dry and loose burnt matter above them, of which the soil of almost the whole country i am describing is composed; and i do not know that any one has ever attended to this circumstance, though i find that many authors, who have described this country, have suspected that parts of it were formed by explosion. wherever then this sort of _tufa_ is found, there is certainly good authority to suspect its having been formed in the same manner as the _tufa_ of this new mountain, for, as i said before, nature is generally uniform in all her operations. it is commonly imagined that the new mountain rose out of the lucrine lake, which was destroyed by it; but in the above account, no mention is made of the lucrine lake; it may be supposed then, that the famous dam, which strabo and many other ancient authors mention to have separated that lake from the sea, had been ruined by time or accident, and that the lake became a part of the sea before the explosion of . if the above-described eruption was terrible, that which formed the monte barbaro (or gauro, as it was formerly called), must have been dreadful indeed. it joins immediately to the new mountain, which in shape and composition it exactly resembles; but it is at least three times as considerable. its crater cannot be less than six miles in circumference; the plain within the crater, one of the most fertile spots i ever saw, is about four miles in circumference: there is no entrance to this plain, but one on the east side of the mountain, made evidently by art; in this section you have an opportunity of seeing that the matter of which the mountain is composed is exactly similar to that of the monte nuovo. it was this mountain that produced (as some authors have supposed) the celebrated falernian wine of the ancients. cuma, allowed to have been the most ancient city of italy, was built on an eminence, which is likewise composed of _tufa_, and may be naturally supposed a section of the cone formed by a very ancient explosion. the lake of avernus fills the bottom of the crater of a mountain, undoubtedly produced by explosion, and whose interior and exterior form, as well as the matter of which it is composed, exactly resemble the monte barbaro and monte nuovo. at that part of the basis of this mountain which is washed by the sea of the bay of puzzole, the sand is still very hot, though constantly washed by the waves; and into the cone of the mountain, near this hot sand, a narrow passage of about paces in length is cut, and leads to a fountain of boiling water, which, though brackish, boils fish and flesh without giving them any bad taste or quality, as i have experienced more than once. this place is called nero's bath, and is still made use of for a sudatory, as it was by the ancients; the steam that rises from the hot fountain abovementioned, confined in the narrow subterraneous passage, soon produces a violent perspiration upon the patient who sits therein. this bath is reckoned a great specifick in that distemper which is supposed to have made its appearance at naples before it spread its contagion over the other parts of europe. virgil and other ancient authors say, that birds could not fly with safety over the lake of avernus, but that they fell therein; a circumstance favouring my opinion, that this was once the mouth of a volcano. the vapour of the sulphur and other minerals must undoubtedly have been more powerful, the nearer we go back to the time of the explosion of the volcano; and i am convinced that there are still some remains of those vapours upon this lake, as i have observed there are very seldom any water-fowl upon it; and that when they do go there, it is but for a short time; whilst all the other lakes in the neighbourhood are constantly covered with them, in the winter season. upon mount vesuvius, in the year , during an eruption, when the air was impregnated with noxious vapours, i have myself picked up dead birds frequently. the castle of baïa stands upon a considerable eminence, composed of the usual _tufa_ and strata of pumice and ashes; from which i concluded i should find some remains of the craters from whence the matter issued: accordingly, having ascended the hill, i soon discovered two very visible craters, just behind the castle. the lake called the mare-morto was also, most probably, the crater, from whence issued the materials which formed the promontory of misenum, and the high grounds around this lake. under the ruins of an ancient building, near the point of misenum, in a vault, there is a vapour, or _mofete_, exactly similar in its effects to that of the grotto del cane, as i have often experienced. the form of the little island of nisida shews plainly its origin[ ]. it is half a hollow cone of a volcano cut perpendicularly; the half crater forms a little harbour called the porto pavone; i suppose the other half of the cone to have been detached into the sea by earthquakes, or perhaps by the violence of the waves, as the part that is wanting is the side next to the open sea. the fertile and pleasant island of procita shews also most evident signs of its production by explosion, the nature of its soil being directly similar to that of baïa and puzzole; this island seems really, as was imagined by the ancients, to have been detached from the neighbouring island of ischia. there is no spot, i believe, that could afford a more ample field for curious observations, than the island of ischia, called enaria, inarime, and pithecusa, by the ancients. i have visited it three times; and this summer passed three weeks there, during which time i examined, with attention, every part of it. ischia is eighteen miles in circumference: the whole of its soil is the same as that near vesuvius, naples, and puzzole. there are numberless springs, hot, warm, and cold[ ], dispersed over the whole island, the waters of which are impregnated with minerals of various sorts; so that, if you give credit to the inhabitants of the country, there is no disorder but what finds its remedy here. in the hot months (the season for making use of these baths), those who have occasion for them flock hither from naples. a charitable institution sends and maintains three hundred poor patients at the baths of gurgitelli every season. by what i could learn of these poor patients, those baths have really done wonders, in cases attended with obstinate tumours, and in contractions of the tendons and muscles. the patient begins by bathing, and then is buried in the hot sand near the sea. in many parts of the island, the sand is burning hot, even under water. the sand on some parts of the shore is almost entirely composed of particles of iron ore; at least they are attracted by the load-stone, as i have experienced. near that part of the island called lacco, there is a rock of an ancient lava, forming a small cavern, which is shut up with a door; this cavern is made use of to cool liquors and fruit, which it does in a short time as effectually as ice. before the door was opened, i felt the cold to my legs very sensibly; but when it was opened, the cold rushed out so as to give me pain; and within the grotto it was intolerable. i was not sensible of wind attending this cold; though upon mount etna and mount vesuvius, where there are caverns of this kind, the cold is evidently occasioned by a subterraneous wind: the natives call such places _ventaroli_. may not the quantity of nitre, with which all these places abound, account in some measure for such extreme cold? my thermometer was unluckily broken, or i would have informed you of the exact degree of the cold in this _ventaroli_ of ischia, which is by much the strongest in its effects i ever felt. the ancient lavas of ischia shew, that the eruptions there have been very formidable; and history informs us, that its first inhabitants were driven out of the island by the frequency and the violence of them. there are some of these ancient lavas not less than two hundred feet in depth. the mountain of st. nicola, on which there is at present a convent of hermits, was called by the ancients epomeus; it is as high, if not higher, than vesuvius, and appears to me to be a section of the cone of the ancient and principal volcano of the island, its composition being all _tufa_ or lava. the cells of the convent abovementioned are cut out of the mountain itself; and there you see plainly that its composition no way differs from the matter that covers herculaneum, and forms the monte nuovo. there is no sign of a crater on the top of this mountain, which rises almost to a sharp point: time, and other accidents, may be reasonably supposed to have worn away this distinctive mark of its having been formed by explosion, as i have seen to be the case in other mountains, formed evidently by explosion, on the flanks of etna and vesuvius. strabo, in his th book, upon the subject of this island, quotes timæus, as having said, that, a little before his time, a mountain in the middle of pithecusa, called epomeus, was shook by an earthquake, and vomited flames. there are many other rising grounds in this island, that, from the nature of their composition, must lead one to think the same as to their origin. near the village of castiglione, there is a mountain formed surely by an explosion of a much later date, having preserved its conical form and crater entire, and producing as yet but a slender vegetation: there is no account, however, of the date of this eruption. nearer the town of ischia, which is on the sea shore, at a place called _le cremate_, there is a crater, from which, in the year or , a lava ran quite into the sea; there is not the least vegetation on this lava, but it is nearly in the same state as the modern lavas of vesuvius. pontano, maranti, and d. francesco lombardi, have recorded this eruption; the latter of whom says, that it lasted two months; that many men and beasts were killed by the explosion; and that a number of the inhabitants were obliged to seek for refuge at naples and in the neighbouring islands. in short, according to my idea, the island of ischia must have taken its rise from the bottom of the sea, and been increased to its present size by divers later explosions. this is not extraordinary, when history tells us (and from my own observation i have reason to believe) that the lipari islands were formed in the like manner. there has been no eruption in ischia since that just mentioned, but earthquakes are very frequent there; two years ago, as i was told, they had a very considerable shock of an earthquake in this island. father goree's account of the formation of the new island in the archipelago (situated between the two islands called kammeni, and near that of santorini) of which he was an eye-witness, strongly confirms the probability of the conjectures i venture to send you, relative to the formation of those islands and that part of the continent above described: it seems likewise to confirm the accounts given by strabo, pliny, justin, and other ancient authors, of many islands in the archipelago, formerly called the ciclades, having sprung up from the bottom of the sea[ ] in the like manner. according to pliny, in the th year of the cxxxvth olympiad, years before the christian æra, the island of thera (now santorini) and theresia were formed by explosion; and, years later, the island hiera (now called the great kammeni) rose up. strabo describes the birth of this island in these words: "in the middle space between thera and theresia flames burst out of the sea for four days, which, by degrees, throwing up great masses, as if they had been raised by machines, they formed an island of twelve stadia in circuit." and justin says of the same island, "eodem anno inter insulas theramenem et theresiam, medio utriusque ripæ et maris spatio, terræ motus fuit: in quo, cum admiratione navigantium, repente ex profundo cum calidis aquis insula emersit." pliny mentions also the formation of aspronisi, or the white island, by explosion, in the time of vespasian. it is known, likewise, that in the year , one of the islands of the azores, near the island of st. michael, rose up from the bottom of the sea, which was in that place fathoms deep; and that this island, which was raised in fifteen days, is three leagues long, a league and a half broad, and rises three hundred and sixty feet above water. father goree, in his account of the formation of the new island in the archipelago, mentions two distinct matters that entered into the composition of this island, the one black, the other white. aspronisi, probably from its very name, is composed of the white matter, which if, upon examination, it proves to be a _tufa_, as i strongly suspect, i should think myself still more grounded in my conjectures; though i must confess, as it is, i have scarcely a doubt left with respect to the country i have been describing having been thrown up in a long series of ages by various explosions from subterraneous fire. surely there are at present many existing volcanos in the known world; and the memory of many others have been handed down to us by history. may there not therefore have been many others, of such ancient dates as to be out of the reach of history[ ]? such wonderful operations of nature are certainly intended by all-wise providence for some great purpose. they are not confined to any one part of the globe, for there are volcanos existing in the four quarters of it. we see the great fertility of the soil thrown up by explosion, in part of the country i have described, which on that account was called by the ancients _campania felix_. the same circumstance is evident in sicily, justly esteemed one of the most fertile spots in the world, and the granary of italy. may not subterraneous fire be considered as the great plough (if i may be allowed the expression), which nature makes use of to turn up the bowels of the earth, and afford us fresh fields to work upon, whilst we are exhausting those we are actually in possession of, by the frequent crops we draw from them? would it not be found, upon enquiry, that many precious minerals must have remained far out of our reach, had it not been for such operations of nature? it is evidently so in this country. but such great enquiries would lead me far indeed. i will only add a reflection, which my little experience in this branch of natural history furnishes me with. it is, that we are apt to judge of the great operations of nature on too confined a plan. when first i came to naples, my whole attention, with respect to natural history, was confined to mount vesuvius, and the wonderful phænomena attending a burning mountain: but, in proportion as i began to perceive the evident marks of the same operation having been carried on in the different parts above described, and likewise in sicily in a greater degree, i looked upon mount vesuvius only as a spot on which nature was at present active; and thought myself fortunate in having an opportunity of seeing the manner in which one of her great operations (an operation, i believe, much less out of her common course than is generally imagined) was effected. such remarks as i have made on the eruptions of mount vesuvius, during my residence at naples, have been transmitted to the royal society, who have done them more honour than they deserved. many more might be made upon this active volcano, by a person who had leisure, a previous knowledge of the natural history of the earth, a knowledge of chemistry, and was practised in physical experiments, particularly those of electricity[ ]. i am convinced, that the smoak of volcanos contains always a portion of electrical matter; which is manifest at the time of great eruptions, as is mentioned in my account of the great eruption of vesuvius in . the peasants in the neighbourhood of my villa, situated at the foot of vesuvius, have assured me, that, during the eruption last mentioned, they were more alarmed by the lightning and balls of fire that fell about them with a crackling noise, than by the lava and the usual attendants of an eruption. i find in all the accounts of great eruptions mention made of this sort of lightning, which is distinguished here by the name of _ferilli_. bracini, in his account of the great one of vesuvius in , says, that the column of smoak, which issued from its crater, went over near an hundred miles of country, and that several men and beasts were struck dead by lightning, issuing from this smoak in its course. the nature of the noxious vapours, called here _mofete_, that are usually set in motion by an eruption of the volcano, and are then manifest in the wells and subterraneous parts of its neighbourhood, seem likewise to be little understood. from some experiments very lately made, by the ingenious dr. nooth, on the _mofete_ of the grotto del cane, it appears that all its known qualities and effects correspond with those attributed to fixed air. just before the eruption of , a vapour of this kind broke into the king's chapel at portici, by which a servant, opening the door of it, was struck down. about the same time, as his sicilian majesty was shooting in a paddock near the palace, a dog dropped down, as was supposed, in a fit; a boy going to take him up dropped likewise; a person present, suspecting the accident to have proceeded from a _mofete_, immediately dragged them both from the spot where they lay, in doing which, he was himself sensible of the vapour; the boy and the dog soon recovered. his sicilian majesty did me the honour of informing me himself of this accident soon after it had happened. i have met with these _mofetes_ often, when i have been making my observations on the borders of mount vesuvius, particularly in caverns, and once on the solfaterra. the vapour affects the nostrils, throat, and stomach, just as the spirit of hartshorn, or any strong volatile salts; and would soon prove fatal, if you did not immediately remove from it. under the ancient city of pompeii, the _mofetes_ are very frequent and powerful, so that the excavations that are carrying on there are often interrupted by them; at all times _mofetes_ are to be met with under ancient lavas of vesuvius, particularly those of the great eruption of . in serao's account of the eruption of , and in the chapter upon _mofetes_, he has recorded several curious experiments relative to this phænomenon. the canonico recupero, who, as i mentioned to you in a former letter, is watching the operations of mount etna, has just informed me, that a very powerful _mofete_ has lately manifested itself in the neighbourhood of etna; and that he found, near the spot from whence it rises, animals, birds, and insects, dead, and the stronger sort of shrubs blasted, whilst the grass and the tenderer plants did not seem to be affected. the circumstance of this _mofete_, added to that of the frequent earthquakes felt lately at rhegio and messina, makes it probable that an eruption of mount etna is at hand. i am alarmed at the length of this letter. by endeavouring to make myself clearly understood, i have been led to make, what i thought, necessary digressions. i must therefore beg of your goodness, that, should you find this memoir, in its present state, too tedious (which i greatly apprehend) to be presented to our respectable society, you will make only such extracts from it as you shall think will be most agreeable and interesting. i am, sir, with great truth and regard, your most obedient humble servant, w. hamilton. [illustration: _plate vi._] references to the map, [plate vi.] . naples. . portici. . resina, under which herculaneum is buried. . torre del greco. . hermitage, at which travellers usually rest, in their way up mount vesuvius. . st. angelo, a convent of calmaldolese, situated upon a cone of a mountain formed by an ancient explosion. . cones formed by the eruption of , and lava that ran from them almost into the sea. . mount vesuvius and somma. . village of somma. . the convent of the madona del arco, under which lavas have been found at feet depth, and which must have proceeded from the mountain of somma, when an active volcano. . ottaiano. . torre del annunziata. . castel a mare, near which the ancient town of stabia is buried, and where pliny the elder lost his life. . vico. . sorrento, and the plain formed evidently by subterraneous fire. . massa. . island of caprea. . the grotto of pausilipo, cut through the mountain anciently, to make a road from naples to puzzole. . point of pausilipo. . the gaiola, where there are ruins of ancient buildings, supposed to have belonged to lucullus. . the island of nisida, evidently formed by explosion. . the lazaret. . the bagnoli. . puzzole, or pozzuolo. . the solfaterra, anciently called forum vulcani: between the solfaterra and the lake of agnano, are the boiling waters of the pisciarelli. . the new mountain, formed by explosion in the year ; the sand of the sea shore at its basis burning hot. . the lake of agnano, supposed the crater of an ancient volcano: here are the baths called st. germano, and the famous grotto del cane. . astruni, which has been evidently a volcano, and is now a royal chace, the crater being surrounded with a wall. . the monte gauro or barbaro, anciently a volcano. . the lake of avernus, evidently the crater of an ancient volcano. . lake of fusaro. . point of misenum, from whence pliny the elder discovered the eruption of vesuvius that proved fatal to him; near this place, in a vault of an ancient building, is a constant vapour, or _mofete_, of the same quality with that of the grotto del cane. . the mare morto, the ancient roman harbour. . baïa; behind the castle are two evident craters of ancient volcanos. . island of procita. . a perfect cone and crater of a volcano near castiglione in the island of ischia. . lava that ran into the sea in the last eruption on this island, in the year , or : the place now called le cremate. . town of ischia and castle. . lake of licola. . lake of patria. . the river volturnus. . capua. . caserta. . aversa. . mataloni. . acerra. . island of ischia, anciently called Ænaria, inarime, and pithecusa. . the mountain of st. nicola, anciently called mons epomeus, supposed the remains of the principal volcano of the island. . castiglione, near which are the baths of gurgitelli. . lacco, near which is that very cold vapour called by the natives _ventarole_. . ancient city of pompeii, where his sicilian majesty's excavations are carrying on at present. . rovigliano. . river of sarno. . cuma. . hot sands and sudatory, called nero's baths. . the lucrine lake, supposed to have been here, and of which there is still some little remain. . villa angelica, sir william hamilton's villa, from whence he has made many of his observations upon mount vesuvius. . cones formed by an ancient eruption called _viuli_; here are likewise cold vapours called _ventaroli_. . high grounds, probably sections of cones of ancient volcanos, being all composed of _tufa_ and strata of loose pumice and burnt matter. . plain of the campagna felice, four or five feet of excellent soil, under which are strata of burnt and erupted matter. ...... marks the boundary of sir william hamilton's observations. letter vi.[ ] to mathew maty, m. d. secretary to the royal society. naples, march , . since i had the pleasure of sending you my letter, in which the nature of the soil of more than twenty miles round this capital is described; examining a deep hollow way cut by the rain waters into the outside cone of the solfaterra, i discovered, that a great part of the cone of that ancient volcano has been calcined by the hot vapours above described. pumice calcined seems to be the chief ingredient, of which several specimens of (as i suppose) variegated unformed marble are composed, and the beautiful variegations in them may have probably been occasioned by the mineral vapours. as these specimens are now sent to the royal society, you will see that these variegations are exactly of the same pattern and colours as are met in many marbles and flowered alabasters; and i cannot help thinking that they are marble or alabaster in its infant state. what a proof we have here of the great changes the earth we inhabit is subject to! what is now the solfaterra, we have every reason to suppose to have been originally thrown up by a subterraneous explosion from the bottom of the sea. that it was long an existing volcano, is plain, from the ancient currents of lava, that are still to be traced from its crater to the sea, from the strata of pumice and erupted matter, of which its cone, in common with those of other volcanos, is composed, and from the testimony of many ancient authors. its cone in many parts has been calcined, and is still calcining, by the hot vapours that are continually issuing forth through its pores; and its nature is totally changed by this chemical process of nature. in the hollow way, where i made these remarks, you see the different strata of erupted matter, that compose the cone, in some places perfectly calcined, in others not, according as the vapours have found means to insinuate themselves more or less. a hollow way, cut by the rains on the back of the mountain on which part of naples is situated, towards capo di china, shews that the mountain is composed of strata of erupted matter, among which are large masses of bitumen, in which its former state of fluidity is very visible. here it was i discovered that pumice stone is produced from bitumen, which i believe has not yet been remarked. some specimens shew evidently the gradual process from bitumen to pumice: and you will observe that the crystalline vitrifications, which are visible in the bitumen, suffer no alteration, but remain in the same state in the perfect pumice as in the bitumen. in a piece of stratum, calcined from the outside of the solfaterra, the form and texture of the pumice stones is very discernible. in several parts of the outside cone, this calcining operation is still carried on, by the exhalation of constant very hot and damp vapours, impregnated with salts, sulphur, alum, &c. where the abovementioned vapours have not operated, the strata of pumice and erupted matter, that compose the cone of the solfaterra, are like those of all the high grounds in its neighbourhood, which i suppose to have been thrown up likewise by explosion. i have seen here, half of a large piece of lava perfectly calcined, whilst the other half out of the reach of the vapours has been untouched; and in some pieces the centre seems to be already converted into true marble. the variegated specimens then, above described, are nothing more than pumice and erupted matter, after having been acted upon in this manner by the hot vapours; and if you consider the process, as i have traced it, from bitumen to pumice, and from pumice to marble, you will think with me, that it is difficult to determine the primitive state of the many wonderful productions we see in nature. i found, in the _tufa_ of the mountain of pausilipo, a fragment of lava: one side i polished, to shew it to be true lava; the other shews the signs of the _tufa_, with which it is incorporated. it has evidently been rounded by friction, and most probably by rolling in the sea. is it not natural then to imagine that there must have been volcanos near this spot, long before the formation of the mountain of pausilipo? this little stone may perhaps raise in your mind such reflections as it did in mine, relative to the great changes our globe suffers, and the probability of its great antiquity. footnotes: [ ] having reflected since upon this circumstance, i rather believe that the weight of the atmosphere in bad weather, preventing the free dissipation of the smoke, and collecting it over the crater, gives it the appearance of being more considerable; whereas in fine weather the smoke is dispersed soon after its emission. it is, however, the common-received opinion at naples (and from my own observation is, i believe, well founded), that when vesuvius grumbles, bad weather is at hand. the sea of the bay of naples, being particularly agitated, and swelling some hours before the arrival of a storm, may very probably force itself into crevices, leading to the bowels of the volcano, and, by causing a new fermentation, produce those explosions and grumblings. [ ] these ashes destroy the leaves and fruit, and are greatly detrimental to vegetation for a year or two; but are certainly of great service to the land in general, and are among the principal causes of that very great fertility which is remarkable in the neighbourhood of volcano's. [ ] in the subsequent eruptions of vesuvius, i have constantly remarked something of the same nature, as appears in my account of the great eruption of . i have found the same remark in many accounts of former eruptions of vesuvius: in the very curious one of the formation of a new mountain near puzzole, in , (as may be seen in my letter to dr. maty, oct. , [ ],) the same observation is made. this phænomenon, is well worthy of a curious inquiry, which might give some light into the theory of the earth, of which, i believe, we are very ignorant. [ ] i am convinced, that it might be very practicable to divert the course of a lava when in this state, by preparing a new bed for it, as is practised with rivers. i was mentioning this idea at catania in sicily, when i was assured, that it had been done with success during the great eruption of etna, in ; that the lava was directing its course towards the walls of catania, and advancing slowly like the abovementioned, when they prepared a channel for it round the walls of the town, and turned it into the sea; that a succession of men, covered with sheep-skins wetted, were employed to cut through the tough flanks of the lava, till they made a passage for that in the centre (which was in perfect fusion) to disgorge itself into the channel prepared for it. a book i have since met with gives the same account of this curious operation; it is intituled, _relatione del nuovo incendio fatto da mongibello . messina, giuseppe bisagni, _. his sicilian majesty's palace at portici, and the valuable collection of antiquities that have been recovered from beneath the destructive lava's of vesuvius, are in imminent danger of being overwhelmed again by the next that shall take its course that way; whereas, by taking a level, cutting away and raising ground, as occasion might require, the palace and museum would, in all probability, be insured, at least against one eruption; and, indeed, i once took the liberty of communicating this idea to the king of naples, who seemed to approve of it. [ ] the late lord morton was pleased to give these specimens to dr. morris, who has made several chemical experiments on them, the result of which will be communicated to the royal society. [ ] from what i have seen and read of eruptions of vesuvius and etna, i am convinced that volcano's lie dormant for several years, nay even for centuries, as probably was the case of vesuvius before its eruption in the reign of titus, and certainly was so before that of the year . when i arrived at naples in , vesuvius was quiet, very seldom smoak was visible on its top; in the year , it seemed to take fire, and has never since been three months without either throwing up red hot stones, or disgorging streams of lava, nor has its crater been ever free from smoak. at naples, when a lava appears, and not till then, it is styled an eruption; whereas i look upon the five nominal eruptions i have been witness to, from march to may , as, in effect, but one continued eruption. [ ] it is certain, that, by constant attention to the smoak that issues from the crater, a very good guess may be given as to the degree of fermentation within the volcano. by this alone i foretold[ ] the two last eruptions, and, by another very simple observation, i pointed out, some time before, the very spot from whence the lava has issued. when the cone of vesuvius was covered with snow, i had remarked a spot on which it would not lie: concluding very naturally that this was the weakest part of the cone, and that the heat from within prevented the snow from lying; it was as natural to imagine that the lava, seeking a vent, would force this passage sooner than another; and so indeed it came to pass. [ ] these are his words: "nubes (incertum procul intuentibus ex quo monte vesuvium fuisse postea cognitum est) oriebatur, cujus similitudinem & formam, non alia magis arbor, quam pinus expresserit. nam longissimo veluti trunco elata in altum, quibusdam ramis diffundebatur, credo quia recenti spiritu evecta, dein senescente eo destituta, aut etiam pondere suo victa, in latitudinem evanescebat: candida interdum, interdum sordida & maculosa, prout terram cineremve sustulerat." plin. lib. vi. ep. . [ ] the windows at naples open like folding-doors. [ ] in several accounts of former eruptions of vesuvius, i have found mention of the ashes falling at a much greater distance; that, in the year and , they had reached constantinople: dio says, that during the eruption of vesuvius in the time of titus--"tantus fuit pulvis ut ab eo loco in africam et syriam et Ægyptum penetraverit." a book printed at lecce, in the kingdom of naples, in mdcxxxii, and intituled, _discorso sopra l'origine de fuochi gettati dal monte vesuvio di gio francesco sorrata spinola galateo_, says, that the th of december, , the very day of the great eruption of vesuvius (though perfectly calm), it rained ashes at lecce, which is nine days journey from the mountain: that the day was darkened by them, and that they covered the ground three inches deep; that ashes of a different quality fell at bari the same day; and that at both these places the inhabitants were very greatly alarmed, not being able to conceive the occasion of such a phænomenon. antonio bulifon, in his account of the same eruption, says, that the ashes fell, and lay several inches deep at ariano in puglia; and i have been assured, by many persons of credit at naples, that they have been sensible of the fall of ashes, during an eruption, at above two hundred miles distance from vesuvius. the abbate giulio cesare bracini, in his account of the eruption of vesuvius, in , says, that the height of the column of smoak and ashes, taken from naples by a quadrant, was upwards of thirty miles. though such uncertain calculations demand but little attention; yet, by what i have seen, i am convinced, that in great eruptions the ashes are sent up to so great a height as to meet with extraordinary currents of air, which is the most probable way of accounting for their having been carried to so great a distance in a few hours. in a book, intituled, _salvatoris varonis vesuviani incendii libri tres: neapoli_, mdcxxxiv, i found a very poetical description of the ashes that lay in the neighbourhood of vesuvius, after the eruption of , in depth, from twenty to a hundred palms: "quare," says this author, "multi patrio in solo requirunt patriam, et vix ibi se credunt vivere ubi certo sciant sese natos, adeo totam loci speciem tempestas vertit." [ ] this conjecture has proved true; for, even in the month of april , i again thrust sticks into some crevices of this lava, and they immediately took fire. on mount etna, in , i observed the lava, that had been disgorged in , smoak in many parts. [ ] in all accounts of great eruptions of mount etna and mount vesuvius, i have found mention of this sort of lightning. pliny the younger, in his second letter to tacitus upon the eruption of vesuvius in the time of titus, says, that a black and horrible cloud covered them at misenum (which is above fifteen miles from the volcano), and that flashes of zig-zag fire, like lightning, but stronger, burst from it; these are his words: "ab altero latere nubes atra et horrenda ignei spiritus tortis vibratisque discursibus rupta, in longas flammarum figuras dehiscebat; fulgoribus illæ et similes et majores erant." this was evidently the same electrical fire, and with which i am convinced that the smoak of all volcanos is pregnant. in several accounts of the great eruption of vesuvius in , mention is made of damage done by the lightning that issued from the column of smoak. bulifon, in particular, says, that, in the neighbourhood of the volcano, people were struck dead in the same manner as if by lightning, without having their cloaths singed. pliny mentions a like instance, which shews that the ancients had observed this phænomenon; for he says, that at pompeii, the day being fair, marcus herennius was struck dead by lightning. these are his words; "in catilianis prodigiis, pompeiano ex municipio m. herennius decurio _serena die_, fulmine ictus est." plin. hist. nat. lib. ii. cap. li. the learned and ingenious father beccaria, at turin, assured me, that he had been greatly pleased with my observations on this species of lightning, as coinciding perfectly with several of his electrical experiments. [ ] "i am well convinced, by this collection, that many variegated marbles, and many precious stones, are the produce of volcanos; and that there have been volcanos in many parts of the world, where at present there are no traces of them visible." this is taken from a prior letter to lord morton, dated april , . [ ] in some accounts of an eruption of vesuvius in , i find mention made of ashes which fell in the shape of crosses, and were looked upon as highly miraculous; but in one book upon this subject, intituled, _athanasii kircheri soc. jes. de prodigiosis crucibus, &c. romæ_, mdclxi, a very philosophical account is given of this phænomenon; he says, that, in , from the th of august to the th of october, vesuvius cast up ashes, impregnated with nitrous, saline, and bituminous sulphur, which upon linen garments took the form of crosses, probably directed by the cross-threads in the linen, and therefore that the salts did not shoot into such a shape when they fell upon garments of woollen; a very particular description of these crosses may be found in page , of the abovementioned book. [ ] i have since found in this stratum of erupted matter at pompeii, stones weighing eight pounds: but many accounts of the great eruption of vesuvius, particularly that of antonio bulifon, mention that a stone like a bomb was thrown from the crater of vesuvius in ; and fell upon the marquis of lauro's house at nola, which it set on fire. as nola is twelve miles from vesuvius, this circumstance seems rather extraordinary: however, i have seen stones of an enormous size shot up to a very great height by mount vesuvius. in may , having a stop watch in my hand, i observed that one of these stones was eleven seconds falling from its greatest height, into the crater from whence it had been ejected. in , a solid stone, measuring twelve feet in height, and forty-five in circumference, was thrown a quarter of a mile from the crater; the eruption of , though by much the most violent of this century, was, comparatively to those of the year and , very mild. [ ] see letter v. in this collection. [ ] it is the common received opinion, that this mountain rose from the bottom of the lucrine lake. i had not seen the very curious and particular account of its formation (which account is in my next letter) when i wrote this, and was therefore in the same error. [ ] this must depend greatly upon the quality of the lava's; some have been in a more perfect state of vitrification than others, and are consequently less liable to the impressions of time. i have often observed on mount vesuvius, when i have been close to the mouth from whence a lava was disgorging itself, that the quality of it varied greatly from time to time: i have seen it as fluid and coherent as glass when in fusion: and i have seen it farinacious, the particles separating as they forced their way out, just like meal coming from under the grindstones. a stream of lava of this sort, being less compact, and continuing more earthy particles, would certainly be much sooner fit for vegetation, than one composed of the more perfect vitrified matter. [ ] this earthquake happened in the year , and destroyed forty-nine towns and villages, nine hundred and twenty-two churches, colleges, and convents; and near one hundred thousand persons were buried in their ruin. [ ] it is intituled, "a true and exact relation of the late prodigious earthquake and eruption of mount Ætna, or monte gibello; as it came in a letter written to his majesty from naples, by the right honourable the earl of winchelsea, his majesty's late embassador at constantinople, who, in his return from thence, visiting catania in the island of sicily, was an eye-witness of that dreadful spectacle; together with a more particular narrative of the same, as it is collected out of the several relations sent from catania; published by authority. printed by t. newcomb, in the savoy, ." "i accepted, says the author, p. , the invitation of the bishop of catania, to stay a day with him, that so i might be the better able to inform your majesty of that extraordinary fire, which comes from mount gibel, fifteen miles distant from that city, which, for its horridness in the aspect, for the vast quantity thereof (for it is fifteen miles in length, and seven in breadth), for its monstrous devastation and quick progress, may be termed an inundation of fire, a flood of fire, cinders, and burning stones, burning with that rage as to advance into the sea six hundred yards, and that to a mile in breadth, which i saw; and that which did augment my admiration was, to see in the sea this matter like ragged rocks, burning in four fathom water, two fathom higher than the sea itself, some parts liquid, and throwing off, not with great violence, the stones about it, which, like a crust of a vast bigness, and red hot, fell into the sea every moment, in some place or other, causing a great and horrible noise, smoak, and hissing in the sea; and that more and more coming after it, making a firm foundation in the sea itself. i stayed there from nine a clock on saturday morning, to seven next morning;" (this must have been towards the middle or latter end of april;) "and this mountain of fire and stones with cinders had advanced into the sea twenty yards at least, in several places; in the middle of this fire, which burnt in the sea, it hath formed like to a river, with its banks on each side very steep and craggy; and in this channel moves the greatest quantity of this fire, which is the most liquid, with stones of the same composition, and cinders all red hot, swimming upon the fire of a great magnitude; from this a river of fire doth proceed under the great mass of the stones, which are generally three fathoms high all over the country, where it burns, and in other places much more. there are secret conduits or rivulets of the liquid matter, which communicates fire and heat into all parts more or less, and melts the stones and cinders by fits in those places where it toucheth them, over and over again; where it meets with rocks or houses of the same matter (as many are), they melt and go away with the fire; where they find other compositions, they turn them to lime or ashes (as i am informed). the composition of this fire, stones, and cinders, are sulphur, nitre, quicksilver, sal ammoniac, lead, iron, brass, and all other metals. it moves not regularly, nor constantly down hill[ ]; in some places it hath made the vallies hills, and the hills that are not high are now vallies. when it was night, i went upon two towers, in divers places; and could plainly see at ten miles distance, as we judged, the fire to begin to run from the mountain in a direct line, the flame to ascend as high and as big as one of the greatest steeples in your majesty's kingdoms, and to throw up great stones into the air; i could discern the river of fire to descend the mountain of a terrible fiery or red colour, and stones of a paler red to swim thereon, and to be some as big as an ordinary table. we could see this fire to move in several other places, and all the country covered with fire, ascending with great flames[ ], in many places, smoaking like to a violent furnace of iron melted, making a noise with the great pieces that fell, especially those which fell into the sea. a cavalier of malta, who lives there, and attended me, told me, that the river was as liquid where it issues out of the mountain, as water, and came out like a torrent with great violence, and is five or six fathom deep, and as broad, and that no stones sink therein. i assure your majesty, no pen can express how terrible it is, nor can all the art and industry of the world quench or divert that which is burning in the country. in forty days time, it hath destroyed the habitations of , persons; made two hills of one, paces high apiece, and one is four miles in compass; of , persons, which inhabit catania, did only remain; all their goods are carried away, the cannons of brass are removed out of the castle, some great bells taken down, the city-gates walled up next the fire, and preparations made to abandon the city. "that night which i lay there, it rained ashes all over the city, and ten miles at sea it troubled my eyes. this fire in its progress met with a lake of four miles in compass; and it was not only satisfied to fill it up, though it was four fathom deep, but hath made of it a mountain." [ ] i have heard since, from some of our countrymen who have measured this tree, that its dimensions are actually as abovementioned, but that they could perceive some signs of four stems having grown together, and formed one tree. [ ] no great stress should be laid upon these observations, as the many inconveniences we laboured under, and the little practice we had in such nice operations, must necessarily have rendered them very inaccurate. the canon recupero, who was our guide, attended mess. glover, fullerton, and brydone, up mount etna in june . the latter is a very ingenious and accurate observer, and has taken the height of many of the highest mountains in the alps. his observations, as the canon informed me, were as follows: at the top of the mountain the quicksilver in the thermometer was degrees below freezing point, when at the foot of the mountain it rose to . at the foot of the little mountain that crowns the volcano the barometer stood at ° - / ', half way up this little mountain it was at ° '; but the wind was too violent for them to attempt any more observations. the barometer and thermometer were of fahrenheit's. mr. brydone remarked, as he went up in the night, that he could distinguish the stars in the milky way with wonderful clearness, and that the cold was much more intense than he had ever felt upon the highest mountains of the alps. [ ] this passage, in cornelius severus's poem upon etna, seems to confirm my opinion: "placantesque etiam cælestia numina thure "summo cerne jugo, vel quâ liberrimus Ætna "improspectus hiat; tantarum semina rerum "si nihil irritet flammas, stupeatque profundum." [ ] a better account of the formation of _tufa_ will be seen in my next letter. [ ] the dates of the eruptions of mount etna, recorded by history, are as follows: before the christian æra four, in the years . . . . after christ, twenty-seven have been recorded, . . . . . . . . . . . . . . . . . . . . . . . . . . . the dates of the eruptions of vesuvius are as follows: after christ-- . . . . . . . . . . . [ , the eruption at puzzole.] . . . . . . . . . . . . . . . . . [ ] pliny, in his account of these islands, in the ix chapter of the third book of his natural history, seems to confirm this opinion. "lipara cum civium romanorum oppido, dicta à liparo rege, qui successit Æolo, antea melogonis vel meliganis vocitata, abest xii millia pass. ab italia, ipsa circuitu paulo minori. inter hanc et siciliam altera, antea therasia appellata, nunc hiera; qui sacra vulcano est, colle in ea nocturnas evomente flammas. tertia strongyle, a lipara millia passuum ad exortum solis vergens, in qua regnavit Æolus, quæ à lipara liquidiore flamma tantum differt: e cujus fumo equinam flaturi sint venti, in triduum prædicere incolæ traduntur; unde ventos Æolo paruisse existimatum. quarta didyme, minor quam lipara. quinta ericusa; sexta phoenicusa; pabulo proximarum relicta. novissima, eademque minima, evonymos." [ ] see plate v. [ ] the abate giulio cesare bruccini describes very elegantly, in his account of the eruption of vesuvius in , his having made an observation of the like nature--his words are (after having particularized the different strata of erupted matter lying one over another)--"parendo appunto che la natura ci abbia voluto lasciare scritto in questa terra tutti gli incendii memorabili raccontati delli autori." [ ] these are his words, book ii. chap. vi. "de pulvere puteolano. "est etiam genus pulveris, quod efficit naturaliter res admirandas. nascitur in regionibus baïanis, et in agris municipiorum, quæ sunt circa vesuvium montem, quod commixtum cum calce et cæmento non modo cæteris ædificiis præstat firmitates, sed etiam moles, quæ construuntur in mari, sub aqua solidescunt. hoc autem fieri hac ratione videtur, quod sub his montibus et terra ferventes sunt fontes crebri, qui non essent, si non in imo haberent, aut de sulfure, aut alumine, aut bitumine ardentes maximos ignes: igitur penitus ignis, et flammæ vapor per intervenia permanans et ardens, efficet levem eam terram, et ibi, qui nascitur tophus, exugens est, et sine liquore. ergo cum tres res consimili ratione, ignis vehementia formatæ in unam pervenerint mixtionem, repente recepto liquore una cohærescunt, et celeriter humore duratæ solidantur, neque eas fluctus, neque vis aquæ potest dissolvere." about baïa, puzzole, and naples, we have an opportunity of remarking the truth of these last words. several of the piers of the ancient harbour of puzzole, vulgarly called caligula's bridge, and which are composed of bricks joined with this sort of cement, are still standing in the sea, though much exposed to the waves; and upon every part of the shore you find large masses of brick-walls rounded and polished by friction in the sea, the brick and mortar making one body, and appearing like a variegated stone. large pieces of old walls are likewise often cut out into square pieces, and made use of in modern buildings instead of stone. soon after the first quotation, pliny says, "si ergo in his locis aquarum ferventes inveniuntur fontes, et in montibus excavatis calidi vapores, ipsaque loca ab antiquis memorantur pervagantes in agris habuisse ardores, videtur esse certum ab ignis vehementia ex topho terraque, quemadmodum in fornacibus et a calce, ita ex his ereptum esse liquorem. igitur dissimilibus, et disparibus rebus correptis, et in unam potestatem collatis, callida humoris jejunitas aqua repente satiata, communibus corporibus latenti calore confervescit et vehementer effecit ea coire, celeriterque una soliditatis percipere virtutem." [ ] scipione falcone, a very good observer, in his _discorso naturale delli cause et effetti del vesuvio_, says, that he saw, after the eruption of vesuvius in (which was attended with hot water), the mud harden almost to a stone in a few days; his words are these--"fatta dura a modo di calcina e di pietra non altrimenti di cenere, perché dopò alcuni giorni vi ci e caminato per sopra e si e conosciuta durissima che ci vogliono li picconi per romperla." this account, with other circumstances mentioned in this letter, make it highly probable, that all the _tufas_ in the neighbourhood of vesuvius have been formed by a like operation. [ ] this piece is now in the museum of the royal society, together with other specimens, mentioned in this and in the following letter. m. m. [ ] letter iv. [ ] strabo, in his fifth book of geography, says, "supra hæc loca situs est vesuvius mons agris cinctus optimis: dempto vertice, qui magna sui parte planus, totus sterilis est, adspectu cinæreus, cavernasque ostendens fistularum plenas et lapidum colore fuliginoso, utpote ab igni exesorum, ut conjecturam facere possit ista loca quondam arsisse, et crateras ignis habuisse, deinde materia deficiente restincta fuisse." diodorus siculus, in his fourth book, describing the voyage of hercules into italy, says, "phlegræus quoque campus is locus appellatur a colle nimirum, qui Ætnæ instar siculæ magnam vim ignis eructabat; nunc vesuvius nominatur, multa inflammationis pristinæ vestigia reservans." and vitruvius, in the sixth chapter of the second book, says, "non minus etiam memoratur antiquitus crevisse ardores et abundasse sub vesuvio monte et inde evomuisse circa agros flammas." tacitus, mentioning the eruption of vesuvius in the reign of titus, seems to hint likewise at former eruptions, in these words: "jam verò novis cladibus, vel post longam sæculorum repetitis afflictæ, haustæ aut abrutæ fecundissima campaniæ ora et urbs incendiis vastata." [ ] bracini, in his account of the eruption of , says, that he found many sorts of sea shells on vesuvius after that eruption; and p. ignatio, in his account of the same eruption, says, that he and his companions picked up many shells likewise at that time upon the mountain: this circumstance would induce one to believe, that the water thrown out of vesuvius, during that formidable eruption, came from the sea. [ ] in book xi. c. . he observes, that about sinuessa and puteoli, "spiracula vocant--alii caroneas scrobes, mortiferum spiritum exhalantes." and seneca, nat. quæst. lib. vi. cap. . "pluribus italiæ locis per quædam foramina pestilens exhalatur vapor, quem non homini ducere, non feræ tutum est. aves quoque si in illum inciderint, antequam coelo meliore leniatur, in ipso volatu cadunt, liventque corpora, et non aliter quam per vim elisæ fauces tument." [ ] i have remarked, that, after a great fall of rain, the degree of heat in this water is much less, which will account for what the padre torre says (in his book, entituled, _histoire et phenomenes du vesuve_), that, when he tried it in company with monsieur de la condamine, the degree of heat, upon reaumur's thermometer, was °. [ ] this very scarce volume has been presented by sir william hamilton to the british museum. m. m. [ ] here again we have an example of the electrical fire attending a great eruption. [ ] the cup, or crater, on the top of the new mountain is now covered with shrubs; but i discovered at the bottom of it, in the year , amidst the bushes, a small hole, which exhales a constant hot and damp vapour, just such as proceeds from boiling water, and with as little smell; the drops of this steam hang upon the neighbouring bushes. [ ] the noxious vapours which lucan mentions to have prevailed at nisida, favour my opinion as to its origin: "--tali spiramine nesis "emittit stygium nebulosis aëra saxis." lucan. lib. vi. [ ] giulio cesare capaccio, in his account of this island, says, that there are eleven springs of cold water, and thirty-five of hot and mineral waters. [ ] by having remarked, that all the implements of stone brought by mess. banks and solander from the new-discovered islands in the south-seas, are evidently of such a nature as are only produced by volcanos; and as these gentlemen have assured me, that no other kind of stone is to be met with in the islands; i am induced to think, that these islands (at so great a distance from any continent) may have likewise been pushed up from the bottom of the sea by like explosions. [ ] any one, the least conversant in volcanos, must be struck with the numberless evident marks of them the whole road from the lake of albano to radicofani, between naples and florence; and yet, though this soil bears such fresh and undoubted marks of its origin, no history reaches the date of any one eruption in these parts. [ ] may not the air in countries replete with sulphur be more impregnated with electrical matter than the air of other soils? and may not the sort of lightning, which is mentioned by several ancient authors to have fallen in a serene day, and was considered as an omen, have proceeded from such a cause? horace says, ode xxxiv. "--namque diespeter "igni corusco nubila dividens "plerumque per purum tonantes "egit equos volucremque currum." "non alias coelo ceciderunt plura sereno "fulgura----" virgil. georgic. i. "aut cum terribili perculsus fulmine civis "luce serenanti vitalia lumina liquit." cic. i. de divin. n. . "--sabinos petit aliquanto tristior, quod sacrificanti hostia aufugerat: quodque tempestate serena tonuerat." sueton. _tit._ cap. . [ ] this letter was not received by dr. maty in its present form: and is rather the substance of an explanatory catalogue, which was sent to that gentleman with sundry specimens of the different materials that compose the soil described in the preceding letter; which catalogue remains, with the specimens, in the museum of the royal society, for the inspection, and, i flatter myself, the satisfaction, of the curious in natural history. [ ] see p. of this collection. [ ] see letter i. p. . [ ] having heard the same remark with respect to the lava's of vesuvius, i determined, during an eruption of that volcano, to watch the progress of a current of lava, and i was soon enabled to comprehend this seeming phænomenon; though it is, i fear, very difficult to explain. certain it is, that the lava's, whilst in their most fluid state, follow always the law of other fluids; but when at a great distance from their source, and consequently incumbered with scoriæ and cinders, the air likewise having rendered their outward coat tough, they will sometimes (as i have seen) be forced up a short ascent, the fresh matter pushing forward that which went before it, and the exterior parts of the lava acting always as conductors (or pipes, if i may be allowed the expression), for the interior parts, that have retained their fluidity by not having been exposed to the air. [ ] the flames lord winchelsea mentions, were certainly produced by the lava having met with trees in the way; or perhaps his lordship may have mistaken the white smoak which constantly rises from a lava (and in the night is tinged by the reflection of the red hot matter), for flame, of which indeed it has greatly the appearance at a distance. i have observed upon mount vesuvius, that, soon after a lava has borne down and burned a tree, a bright flame issues from its surface; otherwise i have never seen any flame attending an eruption. the end. imported from naples, by t. cadell, in the strand. a collection of etruscan, greek, and roman antiquities, from the cabinet of the hon. sir william hamilton, k.b. f.r.s. his majesty's envoy extraordinary at the court of naples. the whole to be comprised in four volumes folio. the plates finely coloured. the price to subscribers l. s. in sheets; six guineas of which is to be paid on the delivery of the first and second volumes, and the remaining three guineas upon the delivery of the third and fourth. after the subscription is closed, the price will be considerably raised. specimens of all the plates of the third volume are arrived, and the fourth and last volume is now doing; so that the public may be assured the whole of this elegant work will be finished with all possible expedition. ** those noblemen and gentlemen who subscribed for the first volume may have the second upon paying l. s. transcriber's notes this document was taken from hand-written letters in the eighteenth century, and also contains quotes from other authors. as such, it's no surprise that there are many spelling and punctuation irregularities. except where explicitly noted below, these were kept as is. spelling variants that were preserved include: "abbate" and "abate;" "abovementioned" and "above-mentioned;" "Ænaria" and "enaria;" "ancient" and "antient" (and derivatives); "astruni" and "astroni;" "averno" and "avernus;" "giulio cesare bracini" and "giulio cesare bruccini;" "castel-a-mare," "castel-a-mare," "castel a mare" and "castle-a-mare;" "centre" and "center;" "colour" and "color" (and derivatives); "deer" and "deers" (for the plural of "deer"); "enquiry" and "inquiry;" "entirely" and "intirely;" "entituled" and "intituled;" "exteriour" and "exterior;" "honour" and "honor;" "interiour" and "interior;" "lavas" and "lava's" (for the plural of "lava"); "mare-morto" and "mare morto;" "mere" and "meer;" "mon-gibello," "mongibello," "mon gibello," "monte gibello" and "mount gibel;" "o'clock" and "a clock;" "procida" and "procita;" "rain water" and "rain-water;" "smoke" and "smoak" (and derivatives); "solfaterra" and "solfa terra;" "strata" and "stratas" (for the plural of "stratum"); "torre dell' annunciata," "torre dell' annunziata" and "torre del annunziata;" "volcanos" and "volcano's" (for the plural of "volcano"); "volcano's" and "volcanos" (for the possessive of "volcano"). changed "that" to "than" on page : "on the top of vesuvius than on that of etna." changed "thermomether" to "thermometer" on page : "fahrenheit's thermometer." inserted missing word "a" on page : "fell a great part of the night." a small right-pointing hand appeared at the beginning of the last line of the advertisement. it was replaced by two asterisks. in the text version of this book, the oe-ligature character was replaced by the separate characters, "oe." state of connecticut state geological and natural history survey bulletin no. drainage modifications and glaciation in the danbury region connecticut by ruth sawyer harvey, ph. d. hartford ~published by the state~ bulletins of the state geological and natural history survey of connecticut. . first biennial report of the commissioners of the state geological and natural history survey, - . . a preliminary report on the protozoa of the fresh waters of connecticut: by herbert william conn. (out of print. to be obtained only in vol. i, containing bulletins - . price $ . , postpaid.) . a preliminary report on the hymeniales of connecticut: by edward albert white. . the clays and clay industries of connecticut: by gerald francis loughlin. . the ustilagineæ, or smuts, of connecticut: by george perkins clinton. . manual of the geology of connecticut: by william north rice and herbert ernest gregory. (out of print. to be obtained only in vol. ii, containing bulletins - . price $ . , postpaid.) . preliminary geological map of connecticut: by herbert ernest gregory and henry hollister robinson. . bibliography of connecticut geology: by herbert ernest gregory. . second biennial report of the commissioners of the state geological and natural history survey, - . . a preliminary report on the algæ of the fresh waters of connecticut: by herbert william conn and lucia washburn (hazen) webster. . the bryophytes of connecticut: by alexander william evans and george elwood nichols. . third biennial report of the commissioners of the state geological and natural history survey, - . . the lithology of connecticut: by joseph barrell and gerald francis loughlin. . catalogue of the flowering plants and ferns of connecticut growing without cultivation: by a committee of the connecticut botanical society. . second report on the hymeniales of connecticut: by edward albert white. . guide to the insects of connecticut: prepared under the direction of wilton everett britton. part i. general introduction: by wilton everett britton. part ii. the euplexoptera and orthoptera of connecticut: by benjamin hovey walden. . fourth biennial report of the commissioners of the state geological and natural history survey, - . . triassic fishes of connecticut: by charles rochester eastman. . echinoderms of connecticut: by wesley roscoe coe. . the birds of connecticut: by john hall sage and louis bennett bishop, assisted by walter parks bliss. . fifth biennial report of the commissioners of the state geological and natural history survey, - . . guide to the insects of connecticut: prepared under the direction of wilton everett britton. part iii. the hymenoptera, or wasp-like insects, of connecticut: by henry lorenz viereck, with the collaboration of alexander dyer macgillivray, charles thomas brues, william morton wheeler, and sievert allen rohwer. . central connecticut in the geologic past: by joseph barrell. . triassic life of the connecticut valley: by richard swann lull. . sixth biennial report of the commissioners of the state geological and natural history survey, - . . the arthrostraca of connecticut: by beverly waugh kunkel. . seventh biennial report of the commissioners of the state geological and natural history survey, - . . eighth biennial report of the commissioners of the state geological and natural history survey, - . . the quaternary geology of the new haven region, connecticut: by freeman ward, ph.d. . drainage, modification and glaciation in the danbury region, connecticut: by ruth sawyer harvey, ph.d. . check list of the insects of connecticut: by wilton everett britton, ph.d. (in press.) bulletins , , , , , , , and are merely administrative reports containing no scientific matter. the other bulletins may be classified as follows: geology: bulletins , , , , , , , , , . botany: bulletins , , , , , . zoölogy: bulletins , , , , , , . these bulletins are sold and otherwise distributed by the state librarian. postage, when bulletins are sent by mail, is as follows: no. $ . no. $ . no. $ . . . . . . . . . . . . . . . . . . . . . . . . . . the prices when the bulletins are sold are as follows, postpaid: no. $ . no. $ . no. $ . . . . . . . . . . . . . . . . . . . . . . . . . . a part of the edition of these bulletins have been assembled in volumes substantially bound in cloth, plainly lettered, and sell for the following prices, postpaid: volume i, containing bulletins - $ . volume ii, containing bulletins - . volume iii, containing bulletins - . volume iv, containing bulletins - . volume v, containing bulletin . it is intended to follow a liberal policy in gratuitously distributing these publications to public libraries, colleges, and scientific institutions, and to scientific men, teachers, and others who require particular bulletins for their work, especially to those who are citizens of connecticut. applications or inquiries should be addressed to ~george s. godard~, _state librarian_, hartford, conn. in addition to the bulletins above named, published by the state survey, attention is called to three publications of the united states geological survey prepared in co-operation with the geological and natural survey of connecticut. these are the following: bulletin . the granites of connecticut: by t. nelson dale and herbert e. gregory. water-supply paper . ground water in the hartford, stamford, salisbury, willimantic and saybrook areas, connecticut: by herbert e. gregory and arthur j. ellis. water-supply paper . ground water in the waterbury area, connecticut: by arthur j. ellis, under the direction of herbert e. gregory. these papers may be obtained from the director of the united states geological survey at washington. catalogue slips. _=connecticut.= state geological and natural history survey._ bulletin no. . drainage modifications and glaciation in the danbury region, connecticut. by ruth s. harvey, ph.d. hartford, . pp., pls., fig., cm. =_harvey, ruth sawyer, ph.d._= drainage modification and glaciation in the danbury region, connecticut. by ruth s. harvey, ph.d. hartford, . pp., pls., figs., cm. =_geology._= harvey, ruth s. drainage modifications and glaciation in the danbury region, connecticut. hartford, . pp., pls., figs., ^cm. state of connecticut public document no. state geological and natural history survey herbert e. gregory, superintendent bulletin no. ~hartford~ printed by the state geological and natural history survey state geological and natural history survey commissioners ~marcus h. holcomb~, governor of connecticut ~arthur twining hadley~, president of yale university ~william arnold shanklin~, president of wesleyan university ~remsen brickerhoff ogilby~, president of trinity college ~charles lewis beach~, president of connecticut agricultural college ~benjamin tinkham marshall~, president of connecticut college for women superintendent ~herbert e. gregory~ _publication approved by the board of control_ drainage modifications and glaciation in the danbury region connecticut by ruth sawyer harvey, ph. d. hartford printed by the state geological and natural history survey contents. ------ page introduction regional relations rocky river description of the river and its valley relation of the valley to geologic structure junction of rocky and housatonic rivers abnormal profile preglacial course the buried channel effect of glaciation the neversink-danbury valley still river statement of the problem evidence to be expected if still river has been reversed a valley wide throughout or broadening toward the south tributary valleys pointing upstream the regional slope not in accord with the course of the still evidence of glacial filling and degrading of the river bed glacial scouring the still-saugatuck divide features of the umpog valley the preglacial divide the still-croton divide introduction features of still river valley west of danbury the still-croton valley glacial lake kanosha divides in the highlands south of danbury the ancient still river departures of still river from its preglacial channel suggested courses of housatonic river glacial deposits beaver brook swamp deposits northeast of danbury deposits between beaver brook mountain and mouth of still river lakes history of the glacial deposits illustrations. ----------- to face page plate i view south on the highland northeast of neversink pond ii a. view up the valley of umpog creek b. view down the valley of umpog creek iii limestone plain southwest of danbury, in which are situated lake kanosha and the danbury fair grounds iv a. view down the housatonic valley from a point one-half mile below stillriver station b. part of the morainal ridge north of danbury v a. kames in still river valley west of brookfield junction b. till ridges on the western border of still river valley, south of brookfield page figure . present drainage of the danbury region . geological map of still river valley . profiles of present and preglacial rocky river . preglacial course of rocky-still river . diagram showing lowest rock levels in rocky river valley . course of still river . map of umpog swamp and vicinity . profiles of rivers . early stage of rocky-still river . five suggested outlets of housatonic river introduction the danbury region of connecticut presents many features of geographic and geologic interest. it may be regarded as a type area, for the history of its streams and the effects of glaciation are representative of those of the entire state. with this idea in mind, the field work on which this study is based included a traverse of each stream valley and an examination of minor features, as well as a consideration of the broader regional problems. much detailed and local description, therefore, is included in the text. the matter in the present bulletin formed the main theme of a thesis on "drainage and glaciation in the central housatonic basin" which was submitted in partial fulfillment of the requirements for the degree of doctor of philosophy at yale university. the field work was done in and under the direction of professor herbert e. gregory. i am also indebted to the late professor joseph barrell and to dr. isaiah bowman for helpful cooperation in the preparation of the original thesis, and to dr. h. h. robinson for assistance in preparing this paper for publication. drainage modifications and glaciation in the danbury region, connecticut -------- by ruth s. harvey regional relations the region discussed in this bulletin is situated in western connecticut and is approximately miles wide and miles long in a north-south direction, as shown on fig. .[ ] throughout, the rocks are crystalline and include gneiss, schist, and marble--the metamorphosed equivalents of a large variety of ancient sedimentary and igneous rocks. for the purposes of this report, the geologic history may be said to begin with the regional uplift which marked the close of the mesozoic. by that time the mountains formed by triassic and jurassic folding and faulting had been worn down to a peneplain, now much dissected but still recognizable in the accordant level of the mountain tops. erosion during cretaceous time resulted in the construction of a piedmont plain extending from an undetermined line to miles north of the present connecticut shore to a point south of long island.[ ] this plain is thought to have been built up of unconsolidated sands, clays, and gravels, the débris of the jurassic mountains. inland the material consisted of river-made or land deposits; outwardly it merged into coastal plain deposits. when the plain was uplifted, these loose gravels were swept away. in new york, pennsylvania, and new jersey, however, portions of the cretaceous deposits are still to be found. such deposits are present, also, on the north shore of long island, and a well drilled at barren island on the south shore revealed not less than feet of cretaceous strata.[ ] the existence of such thick deposits within miles of the connecticut shore and certain peculiarities in the drainage have led to the inference that the cretaceous cover extended over the southern part of connecticut. [footnote : the streams and other topographic features of the danbury region are shown in detail on the danbury and the new milford sheets of the united states topographic atlas. these sheets may be obtained from the director of the united states geological survey, washington, d. c.] [footnote : it was probably not less than miles, for that is the distance from the mouth of still river, where the housatonic enters a gorge in the crystallines, to the sea. fifty-five miles is the distance to the sea from the probable old head of housatonic river on wassaic creek, near amenia, new york.] [footnote : veatch, a. c., slichter, c. s., bowman, isaiah, crosby, w. o., and horton. r. e., underground water resources of long island: u. s. g. s., pp. , p. and fig. , .] a general uplift of the region brought this period of deposition to a close. as the peneplain, probably with a mantle of cretaceous deposits, was raised to its present elevation, the larger streams kept pace with the uplift by incising their valleys. the position of the smaller streams, however, was greatly modified in the development of the new drainage system stimulated by the uplift. the modern drainage system may be assumed to have been at first consequent, that is, dependent for its direction on the slope of the uplifted plain, but it was not long before the effect of geologic structure began to make itself felt. in the time when all the region was near baselevel, the harder rocks had no advantage over the softer ones, and streams wandered where they pleased. but after uplift, the streams began to cut into the plain, and those flowing over limestone or schist deepened, then widened their valleys much faster than could the streams which flowed over the resistant granite and gneiss. by a system of stream piracy and shifting, similar to that which has taken place throughout the newer appalachians, the smaller streams in time became well adjusted to the structure. they are of the class called subsequents; on the other hand, the housatonic, which dates at least from the beginning of the uplift if not from the earlier period of peneplanation, is an antecedent stream. the complex rock surface of western connecticut had reached a stage of mature dissection when the region was invaded by glaciers.[ ] the ice sheet scraped off and redistributed the mantle of decayed rock which covered the surface and in places gouged out the bedrock. the resulting changes were of a minor order, for the main features of the landscape and the principal drainage lines were the same in preglacial time as they are today. it is thus seen that the history of the smaller streams like those considered in this report involves three factors: ( ) the normal tendencies of stream development, ( ) the influence of geologic structure, and ( ) the effect of glaciation. the cover of glacial deposits is generally thin, but marked variations exist. the fields are overspread with coarse till containing pebbles inches in diameter to huge boulders of feet or more. the abundance, size, and composition of the boulders in the till of a given locality is well represented by the stone fences which border fields. [footnote : this stage of glaciation is presumably wisconsin. no definite indication of any older glacial deposits was found.] [illustration: ~fig. .~ present drainage of the danbury region.] the regional depression which marked the close of the glacial period slackened the speed of many rivers and caused them to deposit great quantities of modified or assorted drift. since glacial time, these deposits have been dissected and formed into the terraces which are characteristic of the rivers of the region. a form of terrace even more common than the river-made terrace is the kame terrace found along borders of the lowlands. eskers in the danbury region have not the elongated snake-like form by which they are distinguished in some parts of the country, notably maine; on the contrary, they are characteristically short and broad, many having numerous branches at the southern end like the distributaries of an aggrading river. the material of the eskers ranges from coarse sand to pebbles four inches in diameter, the average size being from one to two inches. no exposures were observed which showed a regular diminution in the coarseness of the material toward their southern end. the clean-washed esker gravels afford little encouragement to plant growth, and the rain water drains away rapidly through the porous gravel. consequently, accumulations of stratified drift are commonly barren places. a desert vegetation of coarse grasses, a kind of wiry moss, and "everlastings" (_gnaphalius decurrens_) are the principal growth. rattlebox (_crotolaria sagittalis_), steeplebush (_spiraea tomentosa_), sweet fern (_comptonia asplenifolia_), and on the more fertile eskers--especially on the lower, wetter part of the slope--golden rod, ox-eyed daisy, birch, and poplar are also present. all the eskers observed were found to be similar: they ranged in breadth across the top from to feet and the side slopes were about degrees. only a single heavily wooded esker was found, and this ran through a forest region. the accumulations of stratified drift are distinguished from other features in the landscape by their smoother and rounder outlines, by their habit of lying unconformably on the bedrock without reference to old erosion lines, and by a slightly different tone in the color of the vegetation covering the water-laid material. the difference in color, which is due to the unique elements in the flora of these areas, may cause a hill of stratified drift in summer to present a lighter green color than that of surrounding hills of boulder clay or of the original rock slopes; in winter the piles of stratified drift stand out because of the uniform light tawny red of the dried grass. [illustration: ~state geol. nat. hist. survey bull. . plate i.~ view south on the highland northeast of neversink pond. the base of a ridge in which rock is exposed is seen at the left; a crescent-shaped lateral moraine bordering the valley lies at the right.] rocky river description of the river and its valley rocky river begins its course as a rapid mountain brook in a rough highland, where the mantle of till in many places is insufficient to conceal the rock ledges (fig. ). near sherman, about four miles from its source, it enters a broad flood plain and meanders over a flat, swampy floor which is somewhat encumbered with deposits of stratified drift and till. rocky hills border the valley and rise abruptly from the lowland. the few tributaries of the river in this part of its course are normal in direction. about six miles below sherman, rocky river enters wood creek swamp, which is - / miles long by about one mile wide and completely covers the valley floor, extending even into tributary valleys. within the swamp the river is joined by squantz pond brook and wood creek. tributaries to wood creek include mountain brook and the stream passing through barses pond and neversink pond. the head of barses pond is separated from the swamp only by a low ridge of till. neversink pond with its inlet gorge and its long southern tributary record significant drainage modifications, as described in the section entitled "the neversink-danbury valley." within and along the margin of wood creek swamp, also east of wood creek and at barses pond, are rounded, elongated ridges of till, some of which might be called drumlins. east of neversink pond is the lateral moraine shown in pl. i. from the mouth of wood creek to jerusalem, rocky river is a quiet stream wandering between low banks through flat meadows, which are generally swampy almost to the foot of the bordering hills. near jerusalem bridge two small branches enter rocky river. immediately north of the bridge is a level swampy area about one-half mile in length. where the valley closes in again, bedrock is exposed near the stream, and beginning at a point one-half mile below (north of) jerusalem, rocky river--a swift torrent choked by boulders of great size--deserves its name. in spite of its rapid current, however, the river is unable to move these boulders, and for nearly three miles one can walk dry-shod on those that lie in midstream. at two or three places below jerusalem, in quiet reaches above rapids, the river has taken its first step toward making a flood plain by building tiny beaches. one-half mile above the mouth of the river the valley widens and on the gently rising south bank there are several well-marked terraces about three feet in height and shaped out of glacial material. a delta and group of small islands at the mouth of rocky river indicate the transporting power of the stream and the relative weakness of the slow-moving housatonic. relations of the valley to geologic structure rocky river is classed with streams which are comformable to the rock structure. this conclusion rests largely on the analogy between rocky river and other rivers of this region. the latter very commonly are located on belts of limestone, or limestone and schist, and their extension is along the strike. the interfluvial ridges are generally composed of the harder rocks. the valleys of the east aspetuck and womenshenuck brook on the north side of the housatonic, and of the still, the umpog, beaver brook, the upper saugatuck, and part of rocky river are on limestone beds (fig. ). in the valleys between town hill and spruce mountain (south of danbury), two ravines northwest of grassy plain (near bethel), and the saugatuck valley north of umpawaug pond, the limestone bed is largely buried under drift, talus, and organic deposits, but remnants which reveal the character of the valley floors have been found. the parallelism between the courses of these streams and that of rocky river and the general resemblance in the form of their valleys, flat-floored with steep-sided walls, as well as the scattered outcrops of limestone in the valley, have led to the inference that rocky river, like the others, is a subsequent stream developed on beds of weaker rock along lines of foliation. [illustration: ~fig. .~ geological map of still river valley.] the geological map of connecticut[ ] shows that the valleys of still river, womenshenuck brook, aspetuck river, and upper rocky river are developed on stockbridge limestone. the lower valley of rocky river is, however, mapped as becket gneiss and thomaston granite gneiss. although the only outcrops along lower rocky river are of granite, it is believed that a belt of limestone or schist, now entirely removed, initially determined the course of the river. the assumption of an irregular belt of limestone in this position would account for the series of gorges and flood plains in the vicinity of jerusalem bridge and for the broad drift-filled valley at the mouth of rocky river. these features are difficult to explain on any other basis. [footnote : gregory, h. e., robinson, h. h., preliminary geological map of connecticut; geol. and nat. hist. survey. bull. , .] junction of rocky and housatonic rivers one of the distinguishing features of rocky river is the angle at which it joins the housatonic (fig. ). the tributaries of a normal drainage system enter their master stream at acute angles, an arrangement which involves the least expenditure of energy. rocky river, however, enters the housatonic against the course of the latter, that is, the tributary points upstream. still river and other southern tributaries of the housatonic exhibit the same feature, thus producing a barbed drainage, which indicates that some factor interfered with the normal development of tributary streams. barbed drainage generally results from the reversal of direction of the master stream[ ], but it is impossible to suppose that the housatonic was ever reversed. as will appear, it is an antecedent master stream crossing the crystalline rocks of western connecticut regardless of structure, and its course obliquely across the strike accounts for the peculiar orientation of its southern tributaries, which are subsequent streams whose position is determined by the nature of the rock. for the same reason, the northern tributaries of the housatonic present the usual relations. [footnote : leverett, frank, glacial formations and drainage features of the erie and ohio basins: u. s. geol. survey mon. , pp. - , figs. and , . see, also, the genoa, watkins, penn yan, and naples (new york) topographic atlas sheets.] abnormal profile the airline distance from the bend in rocky river at sherman to its mouth at the housatonic is - / miles, but the course of the river between these two points is miles, or . times the airline distance. this is a more extraordinary digression than that of tennessee river, which deserts its ancestral course to the gulf and flows northwest into the ohio, multiplying the length of its course - / times. the fall of rocky river between sherman and its mouth is feet or feet to the mile, and were the river able to take a direct course the fall would be feet to the mile. the possibility of capture would seem to be imminent from these figures, but in reality there is no chance of it, for an unbroken mountain ridge of resistant rock lies between the two forks of the river. this barrier is not likely to be crossed by any stream until the whole region has been reduced to a peneplain. measured from the head of its longest branch, rocky river is about miles long and falls feet. of this fall, feet occurs in the first miles and feet in the last - / miles of its course. for the remaining distance of - / miles, in which the river after flowing south doubles back on itself, the fall is feet, or slightly less than - / feet to the mile (fig. , a). [illustration: ~fig. .~ profiles of present and preglacial rocky river. elevations at a, b, c and i are from u. s. g. s. map. elevation at d is estimated from r. e. dakin's records. elevations at e, f, g and h are from r. e. dakin's records. the u. s. g. s. figures for the same are enclosed in parenthesis.] in tabular form the figures, taken from the danbury and new milford atlas sheets and from reports of r. e. dakin, are as follows: miles fall in feet per mile source to sherman . sherman to wood creek . wood creek to jerusalem . . jerusalem to mouth . . near jerusalem, where rocky river makes its sudden change in grade, there is an abrupt change in the form of the valley from broad and flat-bottomed to narrow and v-shaped. the profile of rocky river is thus seen to be sharply contrasted with that of a normal stream, which is characterised throughout its course by a decreasing slope. preglacial course the present profile of rocky river and the singular manner in which the lower course of the river is doubled back on the upper course are believed to represent changes wrought by glaciation. before the advent of the glacier, rocky river probably flowed southward through the "neversink-danbury valley," to be described later, and joined the still at danbury, as shown in fig. . the profile of the stream at this stage in its history is shown in fig. , b. at sherman a low col separates rocky river basin from that of the small northward flowing stream which enters the housatonic about a mile below gaylordsville. streams by headward erosion at both ends of the belt of limestone and schist on which they are situated have reduced this divide to an almost imperceptible swell. the rock outcrops in the channel show that the glacier did not produce any change in the divide by damming, though it may have lowered it by scouring. assume that at one time a divide also existed on the eastern fork of rocky river, for example near jerusalem. according to this hypothesis there was, north of this latter divide, a short northward flowing branch of the housatonic located on a belt of weak rock, similar to the small stream which now flows northward from sherman, and very like any of the half-dozen parallel streams in the rock mass south and southwest of danbury, all of which are subsequent streams flowing along the strike. while these stream valleys were growing, the southern ends of the same weak belts of rock were held by southward-flowing streams which united in the broad limestone area now occupied by the city of danbury. [illustration: ~fig. .~ preglacial course of rocky-still river. dotted lines show present courses of the two rivers.] the southward-flowing streams whose heads were, respectively, above sherman and near jerusalem joined at the southern end of the long ridge which includes towner hill and green mountain. thence the stream flowed southward along the valley now occupied by wood creek and reached still river by way of the valley which extends southward from neversink pond (fig. ). the preglacial course of rocky river, as above outlined, is subject to possible modification in one minor feature, namely, the point where the east and west forks joined. the junction may have been where neversink pond is now situated, or three miles farther south than the indicated junction near the mouth of wood creek. a low ridge of till is the only barrier that at present prevents the western branch from flowing into the head of barses pond and thence into neversink pond (fig. ). as thus reconstructed the greater part of rocky river formerly belonged to the still-umpog system and formed a normal tributary in that distant period when the still joined the saugatuck on its way to the sound (fig. ). however, the normal condition was not lasting, for the reversal of still river, as later described, brought about a complex arrangement of barbed streams (fig. ) which remained until modified by glacial action. in a large stream system which has been reversed, considerable evidence may be gathered from the angle at which tributary streams enter. as the original direction of rocky river in its last - / miles is unchanged, normal tributaries should be expected; whereas between jerusalem and the head of the stream entering neversink pond from the south, in accordance with the hypothesis that this portion of the stream was reversed, tributaries pointing upstream might be expected. such little gullies as join rocky river near its mouth are normal in direction; between jerusalem and the mouth of wood creek, a distance of - / miles, there are no distinct tributaries. south of the mouth of wood creek are four tributaries: ( ) the brook which enters the valley from the west about one mile south of neversink pond, ( ) balls brook, which empties into neversink pond, and ( ) two streams on the east side--mountain brook and one other unnamed (fig. ). all these, except mountain brook, are normal to the reconstructed drainage. the evidence of the tributaries, though not decisive, is thus favorable to the hypothesis of reversal. the buried channel figures and show what is known of the buried channel of rocky river. the only definite information as to rock levels is that derived from the drill holes made by r. e. dakin for the j. a. p. crisfield contracting company in connection with work on a reservoir for the connecticut light and power company. numerous holes were drilled at the points indicated on fig. as no. , d, j, no. + , and no. , but only those showing the lowest rock levels need be considered. in the following account the elevations quoted are those determined by r. e. dakin which differ, as shown in fig. , a, from those of the new milford atlas sheet. between the mouth of wood creek and jerusalem bridge holes made near the river show that the depth of the drift--chiefly sand, gravel, and clay--varies from to feet. the greatest thickness of drift, consisting of humus, quicksand and clay, is feet at a point feet from the east bank of rocky river and about - / miles north of the mouth of wood creek (fig. , d). although some allowance should be made for glacial scouring, the rock level at this point, feet, is so much lower than any other record obtained between this point and danbury that one is obliged to assume a buried channel with a level at danbury at least feet below the rock level found in the lowest well record.[ ] it is probable that this well is not situated where the rock is lowest, that is, it may be on one side of the old still river channel. [footnote : well of j. hornig, rear of bottling works, near foot of tower place, ft. to rock, indicated at _a_, fig. . the well of bartley & clancey, white street, ft. to rock, is also indicated at _b_, fig. .] the level obtained at no. is from a hole drilled within feet of the river. the drill struck rock at an elevation of feet after passing through feet of quicksand, gravel, and till. this is clearly not within the channel as it is quite impossible to reconcile the figure with that at d, less than a mile distant. south of jerusalem bridge at j, feet from the river, a hole was bored through feet of clay, sand, and gravel before striking rock at an elevation of feet. [illustration: ~fig. .~ rocky river valley. diagram indicating lowest rock levels which have been discovered by drilling.] at the point marked no. + , about - / miles from the mouth of rocky river, the evidence derived from drill holes, bored at distances ranging from to feet from the right bank, shows the drift cover to be from to feet in thickness. at feet from the river the drill passed through feet of sand, clay, and gravel before striking rock at feet above sea-level. at no. , about one mile from the mouth of rocky river, a hole drilled feet from the right bank showed feet of drift, consisting of clay, sand, gravel, and boulders. the drill reached rock at feet, which is the figure given by r. e. dakin for the elevation of the river at this point. drill holes made, respectively, at and feet to the right of this one showed a drift cover of feet, so that the underlying rock rises only feet in a distance of feet to the east of the river. the foregoing evidence, showing a rock level at d feet lower than that at no. , leaves no doubt that the preglacial course of rocky river was to the south from no. , and there is nothing in the topography between jerusalem and danbury to make improbable the existence of a buried channel. effect of glaciation the preglacial history of rocky river as outlined assumes that before the glacier covered this part of connecticut the present lower course of rocky river was separated from the rest of the system by a divide situated somewhere between the present mouth of the river and the mouth of wood creek. it remains to be shown by what process rocky river was cut off from its southern outlet into still river and forced up its eastern branch and over the col into a tributary of the housatonic. though the preglacial course of rocky river appears to be more natural than the present one, it is really a longer course to the housatonic; the older route being miles, whereas the present course is miles. this fact explains, in part, why the glacier had little difficulty in altering the preglacial drainage, and how the change so effected became permanent. eccentric as the resulting system of drainage is, it would have been still more so had rocky river when ponded overflowed at the head of its western instead of its eastern fork, taken its way past sherman into the housatonic near gaylordsville, and discharging at this point lost the advantage of the fall of the housatonic between gaylordsville and boardman. in glaciated regions an area of swamp land may be taken as an indication of interference by the glacier with the natural run-off. the swamp in which wood creek joins the upper fork of rocky river (fig. ), was formerly a lake due to a dam built across the lower end of a river valley. although the ponded water extended only a short distance up the steeper side valleys, it extended several miles up the main stream. the whole area of this glacial lake, except two small ponds and the narrow channels through which the river now flows, has been converted into a peat-filled bog having a depth of from to feet.[ ] at the termination of the swampy area on the eastern branch of rocky river no indication is found of a dam such as would be required for so extensive a ponding of the waters. here the valley is very narrow, and though the river bed is encumbered with heavy boulders, rock outcrops are so numerous as to preclude the idea of a drift cover raising the water level. this is just the condition to be expected if rocky river reached its present outlet by overtopping a low col at the head of its former eastern branch. the southern end of the neversink pond valley is the only other place whose level is so low that drift deposits could have interfered with the rocky river drainage. the moraine at the head of this valley, crossing the country some two miles north of the city of danbury and binding together two prominent north-and-south ridges, was evidently the barrier which choked the rocky river valley near its mouth and turned back the preglacial river. when rocky river was thus ponded its lowest outlet was found to be at the head of its eastern fork. here the waters spilled over the old divide and took possession of the channel of a small stream draining into the housatonic. accordingly rocky river should be found cutting its bed where it crosses the former divide. it seems reasonable to regard the gorge half-way between jerusalem bridge and housatonic river as approximately the position of the preglacial divide and to consider the small flat area to the north of jerusalem bridge as a flood plain on softer rock, worn down as low as the outcrops of more resistant rock occurring farther down the valley will permit. the reversal of the river may account for the sudden transition from a flat-bottomed valley to a rocky gorge; and for the abrupt change in the profile, bringing the steepest part of the river near its mouth. the increased volume of water flowing through the channel since glacial time has plainly cut down the bed of the ravine between jerusalem and the river's mouth, but the channel is still far from being graded. [footnote : report of soundings made in by t. t. giffen.] the neversink-danbury valley. between neversink pond and danbury extends a deep rock valley, in places filled with drift. as has been shown, this valley was probably occupied in preglacial time by rocky river, which then flowed southward. at its southern end is still river, which flows through danbury from west to east. the most important tributary of the still rises northwest of the city, just beyond the new york-connecticut boundary line, and has two forks. the northern fork, which drains east lake, padanaram reservoir, and margerie pond, flows along the northeast side of clapboard ridge. the southern fork has two branches; the northern one includes the reservoirs of upper kohanza and lake kohanza, while the upper waters of the southern branch have been recently dammed to form an extensive reservoir. on approaching the city, the northernmost fork (draining east lake) turns sharply out of its southeast course and flows in a direction a little east of north. at the end of clapboard ridge, the stream makes a detour around a knoll of coarse stratified drift. from this turn until it joins still river, a distance of about a mile, the stream occupies a broad and partly swampy valley. at the cemetery in this valley (fig. , c) are two eskers of symmetric form, each a few hundred yards in length and trending nearly parallel with the valley axis. east of the valley, and about - / miles north of the cemetery, is a broad, flat-topped ridge of till with rock exposed at the ends, forming a barrier which doubtless existed in preglacial time. west of the valley is a hill with rock foundation rounded out on the northeast side by a mass of drift. the preglacial course of rocky river was between the outcrops at these two localities. northwest of the cemetery for one and a half miles the uneven surface is formed of till and small patches of stratified drift. in a swamp near the north end of the cemetery is a curved esker with lobes extending south and southwest. one mile north of this swamp is an area of excessively coarse till containing boulders which range in diameter from to feet and forming a low ridge separating two ravines, in which head streams flowing in opposite directions. the area of coarse till is bounded on the north by a long sinuous esker of coarse gravel terminating in a flat fan, which is superposed on a field of fine till. associated with the esker is an interesting group of kames and kettleholes, the largest kettlehole being distinguished by distinct plant zones banding the sides of the depression. north of the area of boulders, eskers, and kames just described lies a swamp whose surface is to feet below the upper level of the kame gravels. soundings made by t. t. giffen revealed the presence of feet of peat and feet of silt overlying firm sand, so that feet is the minimum estimate for the difference in level between the surface of the gravels and the floor of the swamp. below the rocky cliffs which line the valley sides are boulders brought by the ice from near-by ledges, and about one-half mile above the head of the swamp are remnants of a terrace standing to feet above the level of the stream. although the terrace appears to consist of till, it may conceal a rock floor which was cut by a former stream. as the valley is followed toward neversink pond, the various features of a till-coated, rock-floored valley are seen. [illustration: ~fig. .~ course of still river. dotted lines show the preglacial channels.] still river statement of the problem still river presents several unusual features, as shown in fig. . tributaries from the west and south unite at danbury to form a stream flowing northward opposite to the regional land slope. near its junction with the housatonic, the river flows northward, whereas its master stream half a mile distant flows southward. the lower valley of the river is broad and flat and apparently much out of proportion to the present stream; it is, indeed, comformable in size and direction with the valley of the housatonic above the mouth of the still. the housatonic, however, instead of choosing the broad lowland in the limestone formation, spread invitingly before it, turns aside and flows through a narrow gorge cut in resistant gneiss, schist, and igneous intrusives. the headwaters of the still mingle with those of the croton system, and its chief southern branch, the umpog, is interlaced with the sources of the saugatuck on a divide marked by glacial drift and swamps. the explanation of these features involves not only the history of the still river system, but also that of the housatonic. in explanation of the present unusual arrangement of streams in the still river system, four hypotheses may be considered: i. still river valley is the ancient bed of the housatonic from which that river has been diverted through reversal caused by a glacial dam. ii. the housatonic has always had its present southeasterly course, but the still, heading at some point in its valley north of danbury, flowed initially southward through one of four possible outlets. the latter stream was later reversed by a glacial dam at the southern end, or by glacial scouring at the northern end of its valley which removed the divide between its headwaters and the housatonic. iii. the housatonic has always held its present southeasterly course, and the still initially flowed southward, as stated above. reversal in this case, however, occurred in a very early stage in the development of the drainage, as the result of the capture of the headwaters of the still by a small tributary of the housatonic. iv. the housatonic has always held its present southeasterly course, but the still has developed from the beginning as a subsequent stream in the direction in which it now flows. the first hypothesis, that the still is the ancient channel of the housatonic, has been advocated by professor hobbs, who has stated: "that the valley of the still was formerly occupied by a large stream is probable from its wide valley area.... the former discharge of the waters of the housatonic through the still into the croton system, on the one hand, or into the saugatuck on the other, would require the assumption of extremely slight changes only in the rock channels which now connect them.... to turn the river (the housatonic) from its course along the limestone valley some obstruction or differential uplift within the river basin may have been responsible. the former seems to be the more probable explanation in view of the large accumulations of drift material in the area south and west of bethel and danbury." "the structural valleys believed to be present in the crystalline rocks of the uplands due to post-newark deformation may well have directed the course of the housatonic after it had once deserted the limestone ... the deep gorge of the housatonic through which the river enters the uplands not only crosses the first high ridge of gneiss in the rectilinear direction of one of the fault series, but its precipitous walls show the presence of minor planes of dislocation, along which the bottom of the valley appears to have been depressed."[ ] the hypothesis proposed by professor hobbs and also the second and third hypotheses here given involve the supposition of reversal of drainage, and their validity rests on the probability that the stream now occupying still river valley formerly flowed southward. the first and second hypotheses will be considered in the following section. [footnote : hobbs, w. h., still rivers of western connecticut: bull. geol. soc. am., vol. , pp. - , .] evidence to be expected if still river has been reversed if still river occupies the valley of a reversed stream, the following physiographic features should be expected: . a valley with a continuous width corresponding to the size of the ancient stream, or a valley comparatively narrow at the north and broadening toward the south. . tributary valleys pointing upstream with respect to the present river. . the regional slope not in accord with the present course of the river. . extensive glacial filling and ponded waters in the region of the present sources of still river. . strong glacial scouring at the northern end in default of a glacial dam at the southern end of the valley, or to assist a dam in its work of reversing the river. the evidence of glacial erosion would be a u-shaped valley, overdeepening of the main valley, and tributaries ungraded with respect to the main stream. . a valley wide throughout or broadening toward the south at the mouth of still river and for several miles north and south of it there is a plain more than a mile broad. this plain continues southward with a width of about one-half mile until, at brookfield, it is interrupted by ledges of bare rock. a little distance south of brookfield the valley broadens again to one-half mile, and this width is retained with some variation as far as danbury. drift deposits along the border of the valley make it appear narrower in some places than is indicated by rock outcrops. between brookfield and danbury the narrowest place in the valley is southwest of beaver brook mountain, where the distance between the hills of rock bounding the valley is one-fifth of a mile (fig. ). opposite beaver brook mountain, which presents vertical faces of granite-gneiss toward the valley, is a hill of limestone. ice, crowding through this narrow place in the valley, must have torn masses of rock from the side walls, so that the valley is now broader than in preglacial time. the constrictions in the valley near shelter rock are due to the fact that the preglacial valley, now partly buried in till, lies to the north. there are stretches of broad floor in the valley of beaver brook, in the lower valley of umpog creek, in the fields at the south end of main street in danbury, about lake kanosha, and where the danbury fair grounds are situated. in the western part of danbury, however, and at mill plain the valley is very narrow, and at the head of sugar hollow, the valley lying east of spruce mountain, is a narrow col. the broadest continuous area in the still-umpog valley is, therefore, in the lower six miles between brookfield and new milford; south of that portion are several places where the valley is sharply constricted; and beyond the head of the umpog, about one and a half miles below west redding station (fig. ), the saugatuck valley is a very narrow gorge. on the whole, the valleys south and southwest of danbury are much narrower than the valley of the still farther north. it is evident from these observations that still river valley is neither uniformly broad, nor does it increase in width toward the south. but if a broad valley is to be accepted as evidence of the work of a large river, then there is too much evidence in the still river valley. the broad areas named above are more or less isolated lowlands, some of them quite out of the main line of drainage, and can not be grouped to form a continuous valley. they can not be attributed to the housatonic nor wholly to the work of the insignificant streams now draining them. these broad expanses are, in fact, local peneplains developed on areas of soluble limestone. the rock has dissolved and the plain so produced has been made more nearly level by a coating of peat and glacial sand. in a region of level and undisturbed strata, such as the ohio or mississippi valley, a constant relation may exist between the size of a stream and the valley made by it; but in a region of complicated geologic structure, such as western connecticut, where rocks differ widely in their resistance to erosion, the same result is not to be expected. in this region the valleys are commonly developed on limestone and their width is closely controlled by the width of the belt of limestone. even the narrow valleys in the upland southwest of danbury are to be accounted for by the presence of thin lenses of limestone embedded in gneiss and schist. the opinion of hobbs that still river valley is too wide to be the work of the present stream takes into consideration only the broad places, but when the narrow places are considered it may be said as well that the valley is too narrow to be the work of a stream larger than the one now occupying it. valley width has only negative value in interpreting the history of still river. . tributary valleys pointing upstream the dominant topographic feature of western connecticut, as may be seen on the atlas sheets, is elongated oval hills trending north by west to south by east, which is the direction of the axes of the folds into which the strata were thrown at the time their metamorphism took place. furthermore, the direction of glacial movement in this part of new england was almost precisely that of foliation, and scouring by ice merely accentuated the dominant north-south trend of the valleys and ridges. as a result, the smaller streams developed on the softer rocks are generally parallel to each other and to the strike of the rocks. these streams commonly bend around the ends of the hills but do not cross them. the narrowness of the belts of soft rock makes it easy for the drainage of the valleys to be gathered by a single lengthwise stream. the still and its larger tributaries conform in this way to the structure. on the east side of the still-umpog every branch, except two rivulets - / miles south of bethel, points in the normal direction, that is, to the north, or downstream as the river now flows (fig. ). the largest eastern tributary, beaver brook, is in a preglacial valley now converted into a swamp the location and size of which are due entirely to a belt of limestone. it is not impossible that beaver brook may have once flowed southward toward bethel, but the limestone at its mouth, which lies at least feet lower than that at its head, shows that if such were ever the case it must have been before the north-flowing still river had removed the limestone north of beaver brook swamp. on the flanks of beaver brook mountain are three tributaries which enter the river against its present course. examination of the structure reveals, however, that these streams like those on the east side of the river are controlled in their direction by the orientation of the harder rock masses. the southward flowing stream four miles in length which drains the upland west of beaver brook mountain has an abnormal direction in the upper part of its course, but on reaching the flood plain it takes a sharp turn to the north. above the latter point it is in line with the streams near beaver brook mountain and is abnormal in consequence of a line of weakness in the rock. the lowland lying west of umpog valley, extending from main street in danbury to a point one mile beyond bethel, affords no definite evidence in regard to the direction of tributaries. in reconstructing the history of this valley the chief difficulty arises from the old-age condition of the flood plain. drainage channels which must once have existed have been obliterated, leaving a swampy plain which from end to end varies less than feet in elevation. it is likely that in preglacial times the part of the valley north of grassy plain, if not the entire valley, drained northward into still river, as now do umpog creek and beaver brook. from this outlet heavy drift deposits near the river later cut it off. the lowland is now drained by a stream which enters the umpog north of grassy plain. several small streams tributary to the umpog south of bethel also furnish no evidence in favor of the reversal of still river. west of danbury the tributaries of still river point upstream on one side and downstream on the other side of the valley, in conformity with the rock structure which is here diagonal to the limestone belt on which the river is located. their direction in harmony with the trend of the rocks has, therefore, no significance in the earlier history of the river. from the foregoing discussion, it appears that no definite conclusions in regard to the history of still river can be drawn from the angle at which tributaries enter it. the direction of the branches which enter at an abnormal angle can be explained without assuming a reversal of the main stream, and likewise many of the tributaries with normal trends seem to have adopted their courses without regard to the direction of still river. . regional slope not in accord with course of the still although the regional slope of western connecticut as a whole is contrary to that of still river, there is no marked lowering of the hill summits between the source of the river and its mouth. as branches on the south side of the housatonic are naturally to be expected, there is nothing unusual in the still flowing in opposition to the regional slope, except that it flows toward the north instead of the northeast. . evidence of glacial filling and degrading of the river bed hobbs has suggested that the waters of the housatonic may have been ponded at a point near west redding until they rose high enough to overflow into the "fault gorge" below still river station, thus giving the streams of the danbury region an outlet to the sound by this route. this hypothesis calls for a glacial dam which has not been found. it is true there are glacial deposits in the umpog valley south of bethel. the umpog flows as it does, however, not because of a glacial "dam" but in spite of it. the river heads on rock beyond and above the glacial deposits and picks its way through them (fig. ). drift forms the divide at the western end of still river valley beyond mill plain, but the ponded water which it caused did not extend as far as danbury (see discussion of still-croton valley). the sugar hollow pass is also filled with a heavy mantle of drift, but the valley is both too high and too narrow at the col to have been the outlet of the housatonic. it might be assumed that just previous to the advent of the ice sheet still river headed south of its present mouth and flowed southward. in this case the still, when reversed, should have overflowed at the lowest point on the divide between it and the housatonic. it should have deepened its channel over the former divide, and the result would have been a gorge if the divide were high, or at least some evidence of river cutting even if the divide were low. on the contrary, still river joins the housatonic in a low, broad, and poorly drained plain. the existing relief is due to the uneven distribution of drift. the river is now cutting a gorge at lanesville, but the appearance of the valley to the west indicates that glacial deposits forced the river out of its former bed (fig. ) and that no barrier lay between the preglacial still river valley and the housatonic valley. . glacial scouring a reversal of still river may be explained by glacial scouring which caused the northern end of the valley to become lower than the present divides at west redding and mill plain. the evidence of such scour should be an overdeepened, u-shaped main valley and ungraded tributaries. the northern part of still river valley has not the typical u form which results from glacial erosion. as contrasted with the u-shaped glacial valley and the v-shaped valley of normal stream erosion, it might be called rectangular so sharply does the flat valley floor terminate against the steep hillsides. the floor is too smooth and flat and the tributary valleys too closely adjusted to the variant hardness of the rocks to be the work of such a rough instrument as the glacier. a level so nearly perfect as that of the flood plain is the natural result of erosion of soft rock down to a baselevel, whereas glacial scouring tends to produce a surface with low rounded hills and hollows. overdeepening would be expected, because glaciers erode without reference to existing baselevels. that a river valley should be cut out by ice just enough to leave it graded with respect to the main valley would be an unusual coincidence. this is what is found where the still river valley joins the housatonic, and it indicates normal stream erosion. also, if the limestone of the northern still river valley were gouged out by the glacier, the action would in all probability have been continuous in the limestone belt to the north of the housatonic, and where the belt of soft rock crosses the housatonic the river bed would be overdeepened. although the valley of the housatonic near new milford is very flat, as is natural where a river crosses a belt of weak rock, the outcrops are sufficiently numerous to show that it has not been overdeepened. the limestone area along the east aspetuck is largely overlain by till, but here again the presence of rock in place shows that the valley has not been overdeepened. moreover, limestone boulders in the southern part of still river valley are not as abundant as they should be under the hypothesis that the northern part had been gouged out extensively. that the northern part of the still river valley was not deeply carved by ice is shown also by the character of the tributary streams. the three small brooks on the west side of the valley, near beaver brook mountain, were examined to see if their grades indicated an over-deepening of the main valley. these streams, however, and others so far as could be determined, were found to have normal profiles; that is, their grades become increasingly flatter toward their mouths. the streams are cutting through the till cover and are not building alluvial cones where they join the lowland. all their features, in fact, are characteristic of normal stream development. throughout the length of the valley, rock outcrops are found near the surface, showing that the changes produced by the glacier were due to scouring rather than to the accumulation of glacial material. except where stratified drift is collected locally in considerable quantity, the glacial mantle is thin. on the other hand, it has been shown that glacial gouging was not sufficient in amount to affect the course of the stream. the glacier simply cleaned off the soil and rotten rock from the surface, slackening the stream here and hastening it there, and by blocking the course with drift it forced the river at several places to depart slightly from its preglacial course. the evidence shows, therefore, that if still river has suffered reversal, glaciation is not responsible for the change, and thus the first two hypotheses for explaining the history of the valley are eliminated. there remain for discussion the third and fourth hypotheses; the former being that reversal was effected in a very early stage in the development of the drainage, the latter that no reversal has occurred. the choice between these two hypotheses rests on evidence obtained in the umpog, croton, and other valleys of the danbury region. this evidence is presented in the three following sections, after which the former courses of still river will be discussed. the still-saugatuck divide features of the umpog valley the valley of the umpog, which extends from still river to the source of the saugatuck near west redding (fig. ), is a critical area in the study of the still river system. it is possible that this valley once afforded an outlet for still river, and it has been suggested that the housatonic formerly followed this route to long island sound. the relation of this valley to the former drainage system of the danbury region demands, therefore, a careful examination of the features of the valleys occupied by umpog creek and the upper waters of the saugatuck, and of the divide between those streams. [illustration: ~fig. .~ map of umpog swamp and vicinity.] north of bethel the umpog occupies an open valley developed in limestone. knolls of limestone rise to heights of about feet above the floor of the valley and their upper surfaces are cut across the highly, tilted beds. this truncation, together with a general correspondence in height, suggests that these knolls, as well as the rock terraces found between bethel and west redding, and the limestone ridge which forms the divide itself, are portions of what was once a more continuous terrace produced by stream erosion and that they determine a former river level. the absence of accurate elevations and the probability of glacial scour make conclusions regarding the direction of slope of this dissected rock terrace somewhat uncertain. as will be indicated later, however, it seems likely that these terrace remnants mark the course of a southward flowing river that existed in a very early stage in the development of the drainage. south of bethel the old umpog valley, has lost from one-third to one-half its width through deposits of stratified drift (pl. ii, a and b). on the west, gravel beds lie against rock and till; on the east, deposits of sand and coarse gravel form a bench or terrace from to feet broad, which after following the side of the valley for one-half mile, crosses it diagonally and joins the western slope as a row of rounded hills. through this drift the present stream has cut a narrow channel. the narrowest part of the umpog valley is about one mile south of bethel. farther upstream the valley expands into the flat occupied by umpog swamp, which presents several interesting features. the eastern, southern, and western sides of the swamp are formed of irregular masses of limestone and granite-gneiss to feet high. near the northwestern edge of the swamp is a terrace-like surface cut on limestone. its elevation is about the same as that of the beveled rock remnants lying in umpog valley north of bethel. [illustration: ~state geol. nat. hist. survey. bull. . plate ii.~ a. view up the valley of umpog creek. the valley dwindles in the distance to the "railroad divide." in the middle distance is umpog swamp; in the foreground the edge of the southern end of row of kames which points down the valley. b. view down the valley of umpog creek. to the left is the edge of limestone terrace; in the middle distance is the catholic cemetery situated on a terrace of stratified drift; on the right are mounds of stratified drift; in the distance is the granite ridge bounding the valley on the east.] [illustration: ~fig. .~ profiles of rivers. a. profile of present still river and buried channel of 	 umpog-still river. b. profile of preglacial croton-still river. c. profile of preglacial umpog-still river. solid lines show the present levels. dotted lines show preglacial levels.] umpog swamp was formerly a lake but is now nearly filled with organic matter so that only a small remnant of the old water body remains. soundings have revealed no bottom at feet[ ] and the depth to rock bottom is not less than feet. the swamp situated one-half mile southwest of bethel has a depth to rock of feet. in their relation to the still river system these two swamps may be regarded simply as extensions of the umpog creek channel, but when the elevations of their bottoms are compared with that of points to the north and south, where the river flows on rock, it will be seen that a profile results which is entirely out of harmony with the present profile of the river. thus umpog creek falls feet at the point where it spills over the rock ledge into the swamp, and if the feet which measures the depth of umpog swamp be added, the difference in level is seen to be at least feet. a similar calculation locates the bottom of the smaller swamp near bethel at an elevation of feet above sea-level or on the same level as the bottom of umpog swamp. in a straight line - / miles north of bethel, still river crosses rock at a level of feet, or feet higher than the bottom of umpog swamp. at brookfield, - / miles north of the mouth of the umpog, the still crosses rock at feet, and - / miles farther north, it joins the housatonic on a rock floor feet above sea-level (fig. , a). such a profile can be explained in either of two ways: glaciers gouged out rock basins in the weak limestone, or the river in its lower part has been forced out of its graded bed onto rock at a higher level. probably both causes have operated, but the latter has produced more marked effects. umpog creek has its source in a small forked stream which rises in the granite hills east of the south end of umpog swamp. after passing westward through a flat swampy area, where it is joined by the waters from todd pond, the stream turns north and follows a shallow rock gorge until umpog swamp is reached. the divide which separates the present headwaters of the umpog from those of the saugatuck is a till-covered swampy flat about one-quarter mile east of todd pond. this arrangement of tributary streams is correctly shown in fig. and differs essentially from that shown on the danbury atlas sheet. this divide owes its position to the effects of glaciation. deposits of till and the scouring of the bed rock so modified the preglacial surface that the upper part of the saugatuck was cut off and made tributary to the umpog. [footnote : report by t. t. giffen, .] the preglacial divide in order to determine whether still river flowed southward through the saugatuck valley just before the advent of the ice sheet, the borders of umpog swamp and the region to the south and east were examined. it was found that umpog swamp is walled in on the south by ledges of firm crystalline limestone and that the rock-floored ravine leading southward from the swamp, and occupied by the railroad, lies at too high an elevation to have been the channel of a through-flowing stream. a south-flowing still river, and much less an ancient housatonic, could not have had its course through this ravine just previous to glaciation. a course for these rivers through the short valley which extends southeastward from umpog swamp is also ruled out, because the bedrock floor of this hypothetical passageway is feet higher than the floor of the ravine through which the railroad passes. the eastern border of umpog swamp is determined by a ridge of limestone which separates the swamp from lowlying land beyond. this ridge is continuous, except for the postglacial gorge cut by the tributary entering from the east, and must have been in existence in preglacial times. the entire lowland east of this limestone ridge possesses a unity that is not in harmony with the present division of the drainage. the streams from this hillside and those from the west may have joined in the flat-floored valley at the head of the saugatuck and from there flowed into the saugatuck system. the former divide then lay in a line connecting the limestone rim of the swamp with the tongue of highland which the highway crosses south of todd pond (fig. ). the still-croton divide introduction the deep valley extending from the danbury fair grounds to the east branch reservoir in the croton river system, has given rise to the suggestion that the course of the housatonic formerly may have been along the line of still and croton rivers and thence to the hudson.[ ] from the evidence of the topographic map alone, this hypothesis appears improbable. the trend of the larger streams in western connecticut is to the south and southeast; a southwesterly course, therefore, would be out of harmony with the prevailing direction of drainage. also, the distance from the present mouth of still river to tidewater by the still-croton route is longer than the present route by way of the housatonic. [footnote : hobbs, w. h., still rivers of western connecticut: bull. geol. soc. am., vol. , p. , .] features of still river valley west of danbury from danbury to its source still river occupies a valley whose features are significant in the history of the drainage. between danbury and the fair grounds (fig. ) the valley is a v-shaped ravine - / miles long, well proportioned to the small stream now occupying it but entirely too narrow for the channel of a large river. along the valley are outcrops of schist, and granite rock is present on both sides of the valley for a distance of about one-quarter mile. part of the valley is a mere cleft cut in the rock and is unglaciated. at the danbury fair grounds the valley opens out into a marshy plain, through which the river meanders and receives two tributaries from the south. the plain, which extends beyond lake kanosha on the west, has a generally level surface but is diversified in places by mounds of stratified drift. near the railroad a rock outcrop was found which gives a clue to the nature of the broad lowland. the rock consists mainly of schist, but on the side next the valley there is a facing of rotten limestone. this plain, like all the others in this region, is a local peneplain developed on soluble limestone. a better example could not be found to prove the fallacy of the saying that "a broad valley proves the existence of a large river." the plain is simply a local expansion of a valley which on each side is much narrower. no other river than the one flowing through it can have been responsible for the erosion, for the plain is enclosed by hills of gneiss and schist (pl. iii). at mill plain the valley is crowded by ragged rock outcrops which jut into the lowland. here the river occupies a ravine cut in till near the north side of the valley. west of mill plain station the valley is encumbered with ridges of stratified drift, interspersed with heavy accumulations of till. near andrew pond the true width of the valley--one-eighth mile--is shown by rock outcrops on both the north and south slopes. the valley at this point gives no indication of narrowing toward the headwaters; in fact, it becomes broader toward the west. between andrew pond and haines' pond is the divide which separates the waters of the still system from those of the croton. it consists of a jumbled mass of morainal hills, seemingly of boulder clay, that rise from to feet above the level of the ponds. the divide is thus merely a local obstruction in what was formerly a through drainage channel. the still-croton valley it is evident that before the advent of the glacier a stream must have flowed through the still-croton valley past the present divide in order to have excavated the rock valley there found. the housatonic could not have flowed west through this valley if it was as narrow and shallow as is indicated by known rock outcrops; the river could have flowed through it only in a deep narrow gorge which was later buried under drift, but the evidence at hand does not support this view. [illustration: ~state geol. nat. hist. survey bull. . plate iii.~ limestone plain southwest of danbury, in which are situated the danbury fair grounds and lake kanosha.] it is most probable that this valley was made by the preglacial croton river. this explanation demands no change in the direction of still and croton rivers but calls for a divide at some point east of the present one. from a divide between the fair grounds and danbury, a small stream may be supposed to have flowed toward the east, joining the larger northern branch of the still at a point near the middle of the city of danbury. the stream flowing westward from this divide formed the headwaters of one branch of the croton system. the presence of till in a ravine can be used as a criterion for locating the site of a former divide, for where till is present in the bed of a stream the channel is of preglacial date. where the river crosses a divide it should be cutting through rock, though till may be present on the valley slopes. judged by this test, the old divide was situated either just east of the fair grounds plain or at the east end of the ravine described in the preceding topic. of these two positions the one near the fair grounds seems the more likely (fig. ), for at this place the river has excavated a recent channel with steep sides in gneissoid rock. the absence of the limestone at this point may be sufficient in itself to explain the location of the divide. exact measurements of the drift in the upper still valley are needed in order to establish this hypothesis completely and to plot the old channel, but the position of the rock floor of the former channel extending westward from the fair grounds may be fixed approximately. the rock at the assumed divide now stands at feet above sea-level and it is reasonable to assume that ten feet has been removed by glacial scouring and postglacial erosion, making the original elevation feet. the present divide between andrew pond and haines' pond has an elevation of , but the bedrock at this place is buried under feet of drift, so that the valley floor lies at feet. according to these estimates the stream which headed east of the fair grounds had a fall of feet before reaching the site of the present haines' pond (fig. , b). glacial lake kanosha when the croton branch was beheaded by drift choking up its valley west of andrew pond, the ponded waters rose to a height of from to feet and then overflowed the basin on the side toward danbury. the outlet was established across the old divide, and as the gorge by which the water escaped was cut down, the level of the ponded waters was lowered. at the same time, also, the lake was filled by debris washed into it from the surrounding slopes. thus the present flat plain was formed and the old valley floor, a local peneplain developed on the limestone, was hidden. divides in the highlands south of danbury the mountain mass to the south and southwest of danbury, including town hill and spruce, moses, and thomas mountains, is traversed by a series of parallel gorges trending nearly north and south (fig. ). about midway in each valley is a col, separating north and south-flowing streams. two of the valleys, those between spruce and moses mountains, and thomas mountain and town hill, form fairly low and broad passes. they were examined to see whether either could have afforded a southerly outlet for still river. the rock composing the mountains is granite-gneiss and schist with an average strike of n ° w, or very nearly in line with the trend of the valleys. the gneiss was found to be characteristic of the high ridges and schist to be more common in the valleys. no outcrops of limestone were found on the ridges, but at two or three localities limestone in place was found on low ground. from the facts observed it is evident that the stronger features of the relief are due to the presence of bodies of resistant rock, whereas the valleys are due to the presence of softer rock. the series of deep parallel valleys is attributed to the presence of limestone rather than schist. the gorge between spruce and moses mountains, locally called "sugar hollow," narrows southward as it rises to the col, and the rock floor is buried under till and stratified drift to depths of to feet. nevertheless it is probable that the valley was no deeper in preglacial time than it is now. the plan of the valley with its broad mouth to the north favored glacial scour so that the ice widened and deepened the valley and gave it a u form. scouring and filling are believed to have been about equal in amount, and the present height of the divide, about feet, may be taken as the preglacial elevation. this is feet higher than the rock floor of the divide at west redding. the pass could not, therefore, have served as an outlet for still river. the valley west of town hill is similar in form and origin to sugar hollow. the water parting occurs in a swamp, from each end of which a small brook flows. the height of the pass in this valley-- feet-- precludes its use as an ancient outlet for still river. likewise the valley east of town hill affords no evidence of occupation by a southward through-flowing stream. the ancient still river the conclusion that the still-umpog was not reversed by a glacial dam does not preclude the possibility that this valley has been occupied by a south-flowing stream. it is probable that in an early stage in the development of the drainage, the streams of the danbury region reached long island sound by way of the still-umpog-saugatuck valley. along this route, as described under the heading "the still-saugatuck divide," is a fairly broad continuous valley at a higher level than the beds of the present rivers. a south-flowing river, as shown in fig. , brings all the drainage between danbury and the housatonic into normal relations. this early relationship of the streams was disturbed by the reversal of the waters of the ancient still in the natural development of a subsequent drainage. the housatonic lowered the northern end of the limestone belt, in the region between new milford and stillriver village, faster than the smaller south-flowing stream was able to erode its bed. eventually a small tributary of the housatonic captured the headwaters of the south-flowing river, and by the time the latter had been reversed as far south as the present divide at umpog swamp, it is probable that the advantage gained by the more rapid erosion of the housatonic was offset by the saugatuck's shorter course to the sea. as a result the divide between still and saugatuck rivers at umpog swamp had become practically stationary before the advent of the glacier. the complex history of still river is not fully shown in the stream profile, for the latter is nearly normal, except in the rock basins in the valley of the umpog. this is due to the fact that changes in the course of the still, caused by the development of a subsequent drainage through differential erosion, were made so long ago that evidence of them has been largely destroyed. the foregoing conclusion practically eliminates hypothesis iv--that the still developed from the beginning as a subsequent stream in the direction in which it now flows. this hypothesis holds good only for the short portion of the lower course of the present river, that is, the part representing the short tributary of the housatonic which captured and reversed the original still. departures of still river from its preglacial channel between danbury and beaver brook mountain the still departs widely from its former channel, as shown in fig. . at the foot of liberty street in danbury the river makes a sharp turn to the southeast, flows through a flat plain, and for some distance follows the limestone valley of the umpog, meeting the latter stream in a swampy meadow. it then cuts across the western end of shelter rock in a gorge-like valley not over feet wide. outcrops of a gneissoid schist on the valley sides and rapids in the stream bear witness to the youthfulness of this portion of the river channel. an open valley which extends from the foot of liberty street in a northeasterly direction (the railroad follows it) marks the former course of still river, but after the stream was forced out of this course and superimposed across the end of shelter rock by the accumulation of drift in the central and northern parts of the valley, it was unable to regain its old channel until near beaver brook mountain. the deposits of drift not only have kept the still confined to the eastern side of its valley but have forced a tributary from the west to flow along the edge of the valley for a mile before it joins its master stream. about a mile north of brookfield junction, still river valley begins to narrow, and at brookfield the river, here crowded to the extreme eastern side, is cutting a gorge through limestone. the preglacial course of the still in the brookfield region seems to have been near the center of the valley where it was joined by long brook and other short, direct streams draining the hillsides. the glacier, however, left a thick blanket of drift in the middle of the valley which turned the still to the east over rock and forced long brook to flow for more than a mile along the extreme western side of the valley. [illustration: ~fig. .~ early stage of the rocky-still river, antedating preglacial course shown in figure .] the broad valley through which the still flows in the lower part of its course extends northward beyond it for over two miles, bordering the housatonic river. at lanesville near the mouth of the still, the river has cut a gorge feet deep and one-quarter mile long in the limestone. upstream from this gorge the river meanders widely in a flat valley, whereas on the downstream side it has cut a deep channel in the drift in order to reach the level of the housatonic. there is room in the drift-covered plain to the west for a buried channel of still river which could join the housatonic at any point between new milford and stillriver station. if the depth of the drift be taken at feet, there would seem to be no objection to the supposition that the still initially joined its master stream opposite new milford, as shown in fig . after the limestone had been worn down to approximate baselevel, the tendency of the still would have been to seek an outlet farther south in order to shorten its course and reach a lower level on the housatonic. this stage in the evolution of the river may not have been reached before the ice age, and it is thus possible that glacial deposits may have pushed the river to the extreme southern side of its valley, superimposed it over rock, and forced it to cut its way down to grade. suggested courses of housatonic river as possible former outlets for the housatonic, hobbs has suggested the still-umpog-saugatuck valley or the still-croton valley (by way of the east branch reservoir)[ ], whereas crosby has suggested the ten mile-swamp river-muddy brook-croton river valley (by way of webatuck, wing's station, and pawling), or the fall's village-limerock-sharon- webatuck creek-ten mile valley.[ ] the sketch map, fig. , indicates the courses just outlined and one other by way of the norwalk. the latter is the route followed by the danbury and norwalk division of the housatonic railroad. it is natural to assume that the housatonic might have occupied anyone of these lines of valleys, particularly where they are developed on limestone and seem too broad for the streams now occupying them. nevertheless, although each of these routes is on soft rock and some give shorter distances to the sea than the present course, it is highly improbable that the housatonic ever occupied any of these valleys. for had the river once become located in a path of least resistance, such as is furnished by any of these suggested routes, it could not have been dislodged and forced to cut its way for miles through a massive granitic formation, as it does between still river and derby, without great difficulty (pl. iv, a). [illustration: ~fig. .~ five suggested outlets of housatonic river.] an inspection of the larger river systems of connecticut shows that the streams composing them exhibit two main trends. likewise, the courses, of the larger rivers themselves, whether trunk streams or tributaries, combine these two trends, one of which is northwest-southeast and the other nearly north-south. the north-south drainage lines are the result of geologic structure, and many broad, flat-floored valleys, often apparently out of proportion to the streams occupying them, have this direction. on the other hand, the northwest-southeast drainage lines across the strike of formations, coincide with the slope toward the sea of the uplifted peneplain whose dissected surface is represented by the crests of the uplands. the valleys of streams with this trend are generally narrow, and some are gorges where resistant rock masses are crossed. the northwest-southeast trends of master streams thus were determined initially by the slope of the peneplain, whereas the north-south trends represent later adjustments to structure. it is concluded, therefore, that the housatonic between bulls' bridge and derby (fig. ), had its course determined by the slope of the uplifted peneplain and is antecedent in origin. the old headwaters extended northwest from the turn in the river near bull's bridge, whereas that part of the river above bull's bridge was initially a minor tributary. this tributary, because of its favorable situation, in time captured all the drainage of the extensive limestone belt to the north and then became part of the main stream. the lower housatonic, therefore, has always maintained its ancient course diagonal to the strike of formations, and differential erosion, which reaches its maximum expression in limestone areas, is responsible for the impression that the still river lowland and other valleys west of the housatonic may once have been occupied by the latter stream. [illustration: ~state geol. nat. hist. survey bull. . plate iv.~ a. view down the housatonic valley from a point one-half mile below still river station. pumpkin hill, a ridge of resistant schist and quartzite, stands on right. a small island lies in the river. b. part of the morainal ridge north of danbury. till capped by stratified drift one mile north of shelter rock.] [footnote : hobbs, w. h., still rivers of western connecticut: bull. geol. soc. am., vol. , p. , .] [footnote : crosby, w. o., notes on the geology of the sites of the proposed dams in the valleys of the housatonic and ten mile rivers: tech. quart., vol. , p. , .] glacial deposits beaver brook swamp a broad belt of limestone extends along the eastern side of the granite ridge of shelter rock and in preglacial time formed a broad-bottomed valley whose master stream had reached old age. when the glacier came it hampered the drainage by scooping out the rock bottom of the valley in places and by dropping deposits at the mouth of beaver brook valley, thus forming beaver brook swamp or "the flat," as it is called (fig. ). among the deposits at the southern end of beaver brook swamp is considerable stratified drift in the form of smoothly rounded hills or kames, which are situated both on the border of the valley and in the swamp. till containing medium-sized boulders of granodiorite-gneiss occurs along the road which borders the east side of the densely wooded swamp. along the northeastern border of the swamp is a flat-topped terrace of till, perhaps a lateral moraine, through which a small stream heading to the north has cut a v-shaped ravine. a lobe of fine till extends into the valley from the northeast and narrows the outlet. between the railroad and highway, which cross the northern end of the swamp, is an irregular wooded eminence of rock, partly concealed by a veneer of drift. between this knoll and shelter rock are heavy deposits of sand in the form of a short, broad terrace with lobes which point into the still river valley. a similar terrace is found to the northwest on the opposite side of the valley. at the northern end of shelter rock along the blind road leading to the summit is a peninsula-like body of drift which contains huge granite boulders mixed here and there with pockets of sand and gravel. stratified drift was found at the foot of the hill, and till overlying it higher up. the more usual arrangement is boulder clay overlain by modified drift, the first being laid down by the ice itself, the second being deposited by streams from the melting glacier in its retreat. huge boulders, many ten feet or more in diameter, are strewn over the northern slope of shelter rock. deposits northeast of danbury north of the railroad, opposite shelter rock (fig. ), is a most interesting flat-topped ridge of drift which topographically is an extension of the higher rock mass to the northwest. in this drift mass are to be found in miniature a number of the forms characteristic of glacial topography. the broad-topped gravel ridge slopes sharply on the north into a flat-bottomed ravine which is evidently part of the still river lowland. this portion of the valley has been shut off by drift deposits. the drainage has been so obstructed that the stream in the ravine turns northeast away from its natural outlet. in the valley of "x" brook (fig. ) are terraces, esker-like lobes, and detached mounds of stratified drift resting on a foundation of till. along the eastern border of the hill is to be seen the contact between two forms of glacial deposits (pl. iv, b). a mass of stratified drift overlies a hummocky deposit of coarse till, but large boulders occurring here and there on top of the stratified drift show that the ice-laid and water-laid materials were not completely sorted. boulders seem to have been dropping out of the ice at the same time that gravel was being deposited. boulders of granite-gneiss eight feet or more in diameter, carried by the ice from the hills to the north and northeast, are strewn at the foot of the hill. deposits between beaver brook mountain and mouth of still river about a mile beyond beaver brook mountain, the railroad cuts through the edge of a hill feet in height exposing a section consisting of distinctly stratified layers of fine white quartz sand, coarser yellowish sand, and small round pebbles. the quartz sand was used at one time in making glass. farther east where the two tracks of the new york and new england railroads converge, a cut shows a section of at least feet of boulder clay. near the river, limestone boulders are common, indicating that the valley to the north was degraded to some extent by the glacier. [illustration: ~state geol. nat. hist. survey bull. . plate v.~ a. kames in still river valley west of brookfield junction. b. till ridges on the western border of still river valley, south of brookfield.] in the valley at brookfield junction and on its western side, are thick deposits of clean sand. one mile north of brookfield junction, along the western border of the valley, an esker follows an irregular course for several hundred yards approximately parallel to the river and terminates at its southern end in a group of kames (pl. v, a and b). opposite the point where these accumulations occur, is a terrace-like deposit of till. between the gorge at brookfield and the mouth of still river, swampy areas, flat meadows, and small hills of drift occur. in comparison with the still river lowland, the flat land east of green mountain may be called a plateau. the step between the two is made by an east-facing rocky slope, the outline of which has been softened by a lateral moraine separated from the plateau edge by a small ravine. on the lowland below the moraine is a group of kames. near lanesville (fig. ), are thick deposits of water-laid material, including a hill of gravel near the river having a large bowl-shaped depression on one side formed by the melting of an ice block. two and a half miles south of lanesville on the west side of the lowland, a wooded esker extends for about one-quarter mile parallel to the valley axis and then merges into the rocky hillside. lakes the lakes of this region are of two kinds: ( ) those due to the damming of river valleys by glacial deposits and ( ) rock basins gouged out by the ice. among the lakes which owe their origin to drift accumulations in the valleys are andrew and haines' ponds at the head of still river. these are properly parts of the croton river system, but andrew pond has been held back by the deep filling of boulder clay in the valley. lake kanosha, in the same valley, is a shallow lake formed in the drift. the lake south of spruce mountain at the head of the saugatuck seems to be enclosed by drift alone. neversink pond, barses pond, creek pond, and leonard pond are the remnants of larger water bodies now converted into swamps. squantz pond and hatch pond have dams of drift. eureka lake and east lake appear to be rock basins whose levels have been raised somewhat by dams of till. great mountain pond and green's pond, between great mountain and green mountain, are surrounded by rock and their level has been raised several feet by artificial dams. great mountain pond is at least feet above the level of green pond and separated from it by a rock ridge (fig. ). history of the glacial deposits a tongue of the glacier is supposed to have lain in the valley of the umpog and gradually retreated northward after the ice had disappeared from the uplands on either side. the ridge of intermediate height built of limestone and schist, which extends down the middle of the valley, was probably covered by ice for some time after the glacier had left the highlands. when the mountain mass extending from pine mountain to town hill west of the umpog basin and the granite hills to the east terminating in shelter rock are considered in their relation to the movement of the ice, it is apparent that the valley of the umpog must have been the most direct and lowest outlet for glacial streams south of danbury. these streams built up the terraces and other deposits of stratified drift which occupy the valley between bethel and west redding. the heavy deposits of till near west redding mark a halt in the retreating glacier. the boulders at this point are large and numerous, and kames and gravel ridges were formed. the deposits at the divide, supposed to have formed a glacial dam which reversed the umpog,[ ] are much less heavy than at points short distances north and south of the water parting. as the ice retreated, sand and gravel in the form of terraces accumulated along the margin of the umpog valley, where the drainage was concentrated in the spaces left by the melting of the ice lobe from the hillside. among these deposits are the bodies of sand and gravel which lie against the rocky hillslopes most of the way from the umpog-saugatuck divide to bethel. north of bethel, the drainage seems to have been gathered chiefly in streams flowing on each side of the low ridge occupying the center of the valley; consequently the gravel was deposited along the sides and southern end of the ridge and in the sag which cuts across its northern end. the row of kames at the north end of umpog swamp, several knolls of drift in bethel, and the kame-like deposits and esker north of grassy plain were laid down successively as the ice retreated down the valley. during this period, the drainage was ponded between the ice front and the umpog-saugatuck divide. uncovering the still-croton valley did not give the glacial drainage any lower outlet than the umpog-saugatuck divide afforded (fig. , b and c.) the heavy deposits of boulder clay forming the moraine which blocks the rocky river valley indicate the next halting place of the glacier. in this period the ice margin formed an irregular northeast-southwest line about a mile north of danbury. the country west and south of danbury was thus uncovered, but the lower part of still river valley was either covered by the ice sheet or occupied by an ice lobe. the drainage was, therefore, up the river valley, and being concentrated along the valley sides resulted in the accumulation of sand and gravel at the foot of rocky slopes. it is possible that an ice lobe extended down the old rocky river valley, perhaps occupying much of the country between beaver brook mountain and the high ridge west of the valley. the streams issuing from this part of the ice front would have laid down the eskers and kame gravels north of danbury and the thick mantle of drift over which still river flows through the city. as would be expected, this accumulation of material ponded all the north-flowing streams--umpog creek, beaver brook, and smaller nameless ones--and at the same time pushed still river, at its mouth, to the southern side of its valley. beaver brook valley, umpog valley, and all the danbury basin must have been flooded during this period up to the height of the "railroad divide." within the area covered by the city, the valley was filled up to at least feet and probably much more than that above its former level. flowing at this higher level, the river was thrown out of its course and here and there superimposed on hard rock--as, for example, at shelter rock. that part of the drainage coming down the valley opposite beaver brook met the drainage from still river ice lobe in the valley north of shelter rock, and as a result heavy deposits of stratified drift were laid down. the peninsula-like mass of drift beyond the river north of shelter rock appears from its form to have been built up as the delta of southward and eastward-flowing streams; probably the drainage from the hilltops united with streams coming down the two valleys. the lobes of stratified drift extending from the ridge may have been built first, and later the connecting ridge of gravel which forms the top of the hill may have accumulated as additional material was washed in, tying together the ridges of gravel along their western ends. the mingling in this region of stratified drift of all grades of coarseness indicates the union in the same basin of debris gathered from several sources. between danbury and new milford no moraine crosses either the rocky or the still valley, but the abundance of till which overspreads the whole country indicates a slowly retreating glacier well loaded with rock debris. the mounds of stratified drift scattered along the valley doubtless represent the deltas of streams issuing from the ice front. the waters of rocky river were ponded until the outlet near jerusalem was uncovered and the disappearance of ice from the ravine below allowed an escape to the housatonic. stratified drift is present in greatest amount along the valleys of still river and the west fork of rocky river, indicating that these were the two chief lines of drainage. the uplands are practically without stratified drift. along the valley of the housatonic, glacial material is chiefly in the form of gravel terraces; they extend from gaylordsville to new milford, in some places on one side only, in others on both sides of the river. part of these gravel benches are kame terraces, as shown by their rolling tops and the ravine which separates the terrace from the hillside; others may have been made by the river cutting through the mantle of drift which was laid down in the period of land depression at the time of glacial retreat,[ ] or they may be a combination of the two forms. in many places by swinging in its flood plain, the river has cut into the terraces and left steep bluffs of gravel. the valley of womenshenuck brook above merwinsville contains heavy deposits of stratified drift, indicating that this broad valley which extends from kent on the housatonic to merwinsville was an important channel for the water which flowed from the melting ice. [footnote : rice, w. n. and gregory, h. e., manual of the geology of connecticut: conn. geol. and nat. hist. survey bull. , pp. - , .] [footnote : hobbs, w. h., op. cit.] * * * * * transcriber's notes: with the following exceptions, the text presented here is that obtained through scanned images from an original copy of the manuscript. possible typographic errors corrected occuying => occupying plate ii a. "of" repeated emphasis notation: _text_ - italicized =text= - bold ~text~ - small caps transcriber's note: minor typographical errors have been corrected without note. irregularities and inconsistencies in the text have been retained as printed. words printed in italics are noted with underscores: _italics_. hugh miller by w. keith leask famous scots series published by oliphant anderson & ferrier edinburgh and london the designs and ornaments of this volume are by mr. joseph brown, and the printing from the press of messrs. t. and a. constable, edinburgh. preface in the absence of material dealing especially with his last years in edinburgh a complete _life_ of hugh miller will probably never be attempted. i am informed by his daughter, mrs. miller mackay, f. c. manse, lochinver, that the letters and materials sent out to australia to form the basis of a projected biography by his son-in-law and daughter disappeared, and have never been recovered. the recent deaths of his son and of others who knew hugh miller in cromarty and in edinburgh still more preclude the appearance of a full and authentic presentation. to the scientist the works of miller will ever form the best biography; to the general reader and to those who, from various causes, regard biography as made for man and not man for biography some such sketch as the following may, it is believed, not be unacceptable. to treat hugh miller apart from his surroundings of church and state would be as impossible as it would be unjust. accordingly the presentation deliberately adopted has been from his own standpoint--the unhesitating and undeviating traditions of scotland. geology has moved since his day. in the last chapter i have accordingly followed largely in the steps of agassiz in the selection of material for a succinct account of miller's main scientific and theological standpoints or contributions. my best thanks are due to principal donaldson of the university of st. andrews for looking over the proof-sheets; to sir archibald geikie, director-general of the geological survey, london, for his admirable reminiscence of his early friend contained in the last pages of this work; and to my friend j. d. symon, m.a., for the bibliography of miller in the closing appendix. w. k. l. aberdeen, _april_ . contents page chapter i early days--in cromarty chapter ii in edinburgh--the cromarty bank chapter iii the scottish church, - --'the witness' chapter iv in edinburgh--last years chapter v in science appendix: bibliography hugh miller chapter i early days--in cromarty 'a wet sheet and a flowing sea, a wind that follows fast.' allan cunningham the little town of cromarty lies perched on the southern shore of the entrance to the firth of that name, and derives its name from the cromachty, the crook or winding of the magnificent stretch of water known to buchanan and the ancient geographers as the _ecclesiastical history_, 'in which the very greatest navies may rest secure from storms.' in the history of scotland the place is scarcely mentioned; and, indeed, in literary matters is known only from its association with the names of hugh miller and the rare figure of sir thomas urquhart of cromarty, who had followed charles ii. to the 'crowning mercy' of worcester fight, to land at last in the tower. but for the silence of history the imagination or the credulity of the knight has atoned, by the production of a chronicle which rivals fairly the _ecclesiastical history_ of the old wandering scottish scholar dempster, who had in italy patriotically found the maccabees to be but an ancient highland family. according to urquhart, whose translation of rabelais has survived his eccentric disquisitions in genealogy and history, alypos, the forty-third lineal descendant of japhet, was the first to discover cromarty, and, when the scythians under ethus pitched on the moor bounding the parish on the north, they had been opposed by the grandson of alcibiades; in proof of which sir thomas could triumphantly point to remaining signs of 'trenches and castrametation' with a confidence which would have won the heart of jonathan monkbarns in _the antiquary_. the population of the district is essentially a mixed one, and strongly retains the distinctive features of the scandinavian and the gael. from shetland to the ord of caithness, the population of the coast is generally, if not wholly, of the former type. beyond the ord to the north of the firth of cromarty, we find a wedge of celtic origin, while from the southern shore to the bay of munlochy the scandinavian element again asserts itself. thus, as carlyle escaped being born an englishman by but a few miles, the separation from the celtic stratum was, in miller's case, effected by the narrow single line of the one-mile ferry. in later years, at all events, he would refer with evident satisfaction to his teutonic origin. there was, as we shall have occasion to notice, a certain celtic lobe of imagination on the mother's side, but in his mental and political character the great leading features of the other race were undoubtedly predominant. whence buchanan drew the possibilities of great fleets in the firth of cromarty is unknown unless he had in his memory some of the vessels of the old mariners, such as sir andrew wood and the bold bartons, or even the 'verrie monstrous schippe the great michael' that 'cumbered all scotland to get her to sea.' certain it is that for many a day its position had marked out the town as the natural centre of a coasting trade, though shortly after the union the commerce of the place which had been considerable had declined. the real commencement of the prosperity of the place was due to the energy of a native, william forsyth, whose life miller has sketched in a little memoir originally drawn up for the family, and subsequently republished in his _tales and sketches_ under the title of 'a scottish merchant of the eighteenth century.' forsyth had been appointed by the british linen company, established about in edinburgh to promote the linen trade, its agent in the north throughout the whole district extending from beauly to the pentland firth. the flax which was brought in vessels from holland was prepared for use in cromarty, and distributed by boats along the coast to wick and thurso. in the early days of the trade the distaff and the spindle were in general use; but forsyth's efforts were successful in the introduction of the spinning-wheel, though the older means of production lasted far into this century in the west of ross and in the hebrides. the coasting schooners of the agent were the means of introducing into the town teas and wines, cloth, glass, flemish tiles, swedish iron, and norwegian tar and spars. the rents of the landed proprietors were still largely paid in kind, or in the feudal labour by which the baron of bradwardine managed to eke out a rather scanty rent roll. in this way the _mains_ or the demesnes of the laird were tilled and worked, and the martinmas corn rents were stocked in a barn or 'girnal,' like that of the antiquary's famous john of legend, often to cause a surplus to hang on the hands of the proprietor, until the idea was fortunately devised of exporting it to england or to flanders for conversion into malt. ship-carpentry or boat-building upon a humble scale had been long established, and the coasting trade lay between the north, leith, newcastle, and london. the scottish sailors then on the eastern coast enjoyed a strong reputation for piety, such as, we fear, their descendants have not maintained. john gibb of borrowstouness, the antiquary may remember as the founder of the now forgotten sect of gibbites or 'sweet singers,' who denounced all tolls and statutory impositions, abolished the use of tobacco and all excisable articles, and finally made a pilgrimage to the pentland hills to see the smoke and the desolation of edinburgh as foretold by their founder. the wardrobes and scrutoires of the local cabinet-maker, donald sandison, enjoyed a reputation through the north, and were, far into this century, found in the houses of ross, together with the old eight-day clocks made in kilwinning. but the great founder of its modern prosperity was george ross, the son of a small proprietor in easter ross, who, after amassing a fortune as an army-agent as the friend of lord mansfield and the duke of grafton, had in purchased the estate of cromarty. when he started his improvements in his native district, there was not a wheeled-cart in all the parish, and the knowledge of agriculture was rude. green cropping and the rotation of crops were unknown, and in autumn the long irregular patches of arable land were intersected by stretches of moorland that wound deviously into the land, like the reaches of the cromarty and the beauly firths. though long opposed by tenacious local prejudices, he at length triumphed over the backward habits of the people, who yoked their oxen and their horses by the tail, and who justified their action by an appeal to the argument from design, and by a query as to what other end in creation such tails had been provided? ross also established in the town a manufactory for hempen cloth, and erected what at the time was the largest ale-brewery in the north. a harbour was built at his own expense, and a pork trade of a thriving nature set on foot, wheat reared, the rotation of crops introduced, a nail and spade manufactory set up, and lace manufactures brought from england. such, then, was the condition of cromarty at the beginning of the present century. far different was that of the surrounding highlands. protestantism had been at an early period introduced into ross and sutherland by its earls and by lord reay. the earl of sutherland had been the first to subscribe the national covenant in greyfriars; and, after the suppression of the first jacobite rising, sir robert munro of fowlis, as commissioner of the confiscated estates, had set himself to the creation of parishes and presbyteries in remote districts, where the church of scotland before had been unknown. in the better class of houses the old highland fireplace, like a millstone, still occupied its place in the centre, with no corresponding aperture in the roof for the smoke. in the western districts the greatest distress prevailed, for the country was at the parting of the ways in a time of transition. about the beginning of the present century the results of the french revolution began to make themselves felt. through the long war the price of provisions rose to famine price, and the impecunious highland laird, like his more degenerate successor that battens on the sporting proclivities of the cockney or american millionaire, set himself to the problem of increasing his rent-roll, and the system of evictions and sheep-farming on a large scale commenced. the sutherland clearances forced the ejected highlanders to canada and the united states, while the poorer classes drifted down from the interior to the already overpopulated shore-line, where they eked out, as crofters or as fishermen, a precarious existence without capital or the acquired experience of either occupation, and laid the seeds of the future crofter question. the manufacture of kelp, which for a time rendered profitable to many a highland proprietor his barren acres on a rocky shore, was not destined to long survive the introduction of the principles of free trade. the potato blight succeeded finally in reducing the once fairly prosperous native of the interior to chronic poverty and distress. on the west coast, the heavy rainfall is unfavourable to agriculture on any extended scale. from assynt to mull the average rain-gauge is thirty-five inches, and the cottars of ross were threatened with the fate of the irish in connemara, through periodic failures in the herring fishery and liabilities for their scanty holdings to their landlords. miller found the men of gairloch, in , where the public road was a good day's journey from the place, still turning up or scratching the soil with the old highland _cass-chron_, and the women carrying the manure on their backs to the fields in spring, while all the time they kept twirling the distaff--old and faded before their time, like the women in some of the poorer cantons the traveller meets with in switzerland. their constant employment was the making of yarn; and, as we have seen, the spinning-wheel was for long as rare as the possession of a plough or horse. the boats built for the fishing were still caulked with moss dipped in tar and laid along the seams, the ropes being made of filaments of moss-fir stripped with the knife, while the sails were composed of a woollen stuff whose hard thread had been spun on the distaff, for hemp and flax were practically unknown. such, in , had at largs been the equipment of the galleys of haco, 'when norse and danish galleys plied their oars within the firth of clyde, and floated haco's banner trim above norweyan warriors grim.' _marmion_, iii. xx. such, too, had been the traditional custom for centuries after of the boatbuilders in the western highlands. in cromarty, then, on the th of october , hugh miller was born--in a long, low-built six-roomed house of his great-grandfather, one of the last of the old buccaneers of the spanish main, who had thriftily invested his pieces of eight in house-property in his native place. his mother was the great-granddaughter of donald roy of nigg, of whom, as a kind of northern peden or cargill, traditions long lingered. in his early days, donald had been a great club and football player in the sunday games that had been fostered in the semi-celtic parish by king james's _book of sports_, and which, it may be remembered, had been popular in the days of dugald buchanan of rannoch at a time when the observance of the seventh day and of the king's writ never ran beyond the pass of killiecrankie. at the revolution, however, donald had become the subject of religious convictions; and when, on the death of balfour of nigg in , an unpopular presentee, mr. patrick grant, was forced upon the parish, resistance was offered. four years before this, gillespie of carnock had been deposed on the motion of john home, author of _douglas_, seconded by robertson of gladsmuir, the subsequent historian of _charles v._, for his refusal to participate in the settlement of richardson to inverkeithing; and when some of the presbytery, in fear of similar proceedings, had met for the induction, they found an empty church and an old man protesting that 'if they settled a man to the walls of that kirk, the blood of the parish of nigg would be required at their hands.' for long the entire parish clung to the church of scotland, but never could they be induced to enter the building again, and so they perforce allied themselves to the burgher secession. thus early was the non-intrusion principle made familiar to miller, and thus early were made manifest the miserable effects of the high-handed policy which, begun in the long reign of robertson, was destined a century later to have such disastrous results. in early youth his father had sailed in an east indiaman, and during the intervals of his indian and chinese voyages had learned to write and add to his nautical knowledge stores of general reading and information not then common among sailors. storing up, instead of drinking, his grog-money, he drove a small trade with the natives of these countries in little articles that had excited their curiosity, and for which, hints his distinguished son, the custom-house dues were never very punctually or rigorously paid. pressed, however, by a man-of-war that had borne down upon the indiaman when in a state of mutiny, after a brief experience of the stern discipline of the navy not yet tempered by the measures of reform introduced after the mutiny of the nore, he returned when not much turned thirty to cromarty, where his savings enabled him to buy a coasting sloop and set up house. for this the site was purchased at £ , a very considerable sum in those days, and thus his son could, even in the high franchise qualifications after the reform bill, exercise the right of voting for the whig party. the kelp trade, of which we have spoken, among other things engaged the efforts of his father, who had been appointed agent in the north and hebrides for the leith glass-works. driven by a storm round cape wrath and through the pentland firth, the vessel, after striving to reach the sheltered roadstead of the moray firth, was forced to put in at peterhead. on the th of november he set sail, but foundered with all hands, by the starting, as was believed, of a plank. during more than one hundred years the sea had been the graveyard of the family: miller's father, grandfather, and two grand-uncles had been all drowned at sea. at the time of his father's death the son had just by one month completed his fifth year. at that time happened the circumstance which he himself relates, and which we mention here in this place both for the interest attaching to it in the history of his own mental development, and for various subtle psychological reasons to which we shall advert later, and which cannot fail to be observed by the careful student of his works. the last letter to his wife had been written by his father from peterhead, and on its receipt, 'the house-door, which had been left unfastened, fell open, and i was despatched from her side to shut it. i saw at the open door, within less than a yard of my breast, as plainly as ever i saw anything, a dissevered hand and arm stretched towards me. hand and arm were apparently those of a female: they bore a livid and sodden appearance; and, directly fronting me, where the body ought to have been, there was only blank transparent space, through which i could see the dim forms of the objects beyond. i commemorate the story as it lies fixed in my memory, without attempting to explain it.' in after years he would say of such mental or visual hallucinations that they were such as 'would render me a firm believer in apparitions, could i not account for them in this way, as the creatures of an imagination which had attained an unusual and even morbid strength at a time when the other mental faculties were scarcely at all unfolded.' in this connection the similar case of chatterton need only be alluded to, but the question will be treated again in describing his later years. like burns, carlyle, and scott, miller seems to have borne the powerful impress, mentally and physically, of his father. yet, like the mothers of the first two, mrs. miller bequeathed to her son his store of legend and story and the imagination that was thus so early awakened. the new house which his father had built remained for some little time after his death untenanted; and, as the insurance of the sloop was deferred or disputed by an insolvent broker, his mother had recourse to her needle as the means by which she could best support her family. three children had been born, and her brothers came to her assistance and lightened her task by taking her second daughter, a child of three, to live with them. both of the girls died of a fever within a few days of each other, the one in her twelfth, and the other in her tenth year. of these two uncles, the james and sandy of his _schools and schoolmasters_, miller has spoken with deserved affection and loyalty. to them he confesses he owed more real education than ever he acquired from all other sources; and, belonging as they do to the class of humble and worthy men that seems pre-eminently the boast and pride of scottish life, they will merit a detailed account. of this type some little knowledge had been made known by lord jeffrey in his review of cromek's _reliques_, where such men as the father of burns and those of his immediate circle were first introduced to their proper place as those 'from whom old scotia's grandeur springs.' in his own _reminiscences_, carlyle has added to our acquaintance with these men through his sketch of his own father and others, who are, says professor blackie, the natural outcome of the republican form of our scottish church government, and of the national system of education so early developed by knox and the first reformers. the elder of the two brothers, james, was a harness-maker in steady employment in the surrounding agricultural district, so that from six in the morning till ten at night his time would be fully occupied, thus leaving him but scanty leisure. but, in the long evenings, he would fix his bench by the hearth, and listen while his nephew or his own younger brother or some neighbour would read. in the summer, he would occupy his spare hours upon his journeys to and from his rural rounds of labour in visiting every scene of legend and story far and near, and so keen were his powers of perception and ready expression in matters of a historical and antiquarian nature, that his nephew regrets he had not become a writer of books. some part of this information, however, he has attempted to preserve in his _scenes and legends_. to the younger brother, alexander, he seems to have been even more indebted. if to the one he owed his gift of ready and natural expression, it was to the other that he was indebted for his powers of observation. originally educated as a cart-wright, he had served for seven years in the navy, sailing with nelson, witnessing the mutiny at the nore, the battle of camperdown under duncan, and sharing the egyptian campaign of abercromby. even on his discharge, he was still ready in to shoulder a musket as a volunteer, when napoleon at boulogne 'armed in our island every freeman.' the scientific interest, too, of the man may be judged from the fact that in the egyptian expedition, during the landing, he managed to transfer a murex to his pocket from the beach, and the first ammonite which formed the nucleus of his nephew's geological collection was also brought home from an english liassic deposit. facts like these and the presence of such men should go far to dispel much of the cheap sentiment introduced into the current of scottish life by writers such as smiles and others, who profess to be ever finding some 'peasant' or 'uneducated genius' in the subjects of their all too unctuous biographies. such a class has really no existence in scotland, and between such men as miller, burns, or even the unfortunate and sorely buffeted bethunes, there is a great gulf fixed when they are sought to be brought into relation with men like john clare and robert bloomfield. all the scotchmen, born in however originally humble circumstances, had the advantage of education at the parish school; and, slight though in some cases the result may have been, it yet for ever removes the possibility of illiteracy which the english reader at once conjures up at the sound of such surroundings. the more the critic studies the facts of burns' early years and education, and the really remarkable stock of information with which he was to rouse the honest wonder of dugald stewart--his mathematical attainments and his philosophical grasp, not to mention his possession of a very powerful english prose style that makes every line of his _letters_ really alive and matterful--the less we shall hear of peasant genius and untaught writers. we question if one half of the members of the edinburgh bar, such as lockhart has described them at the arrival of burns in edinburgh, had reached such an amount of general and poetical literature as that easily held in command by the poet. we have heard an old schoolfellow of edward irving and carlyle at the burgh school of annan remark on the misconception of froude as to the true social rank of their respective parents. horace and burns seem, as theodore martin has shown, not unlike in the matter of their fathers, and the possession of such sets their children far out of that circle of contracted social and moral surroundings in which the biographers of the smiles class have too long set them. the knowledge of his letters miller seems, like the elder weller, to have acquired from a study of the local signboards, and in his sixth year he was sent to a dame's school, where he spelt his way through the old curriculum of a child's education in scotland--the shorter catechism, the proverbs, and the new testament. he managed to discover for himself the story of joseph; and even in the old six-volume edition of lintot the genius of homer was early made manifest. _the pilgrim's progress_, evidently in some such form as macaulay has described, made for the cottage, followed; and, in course of time, the collection of books which his father had left was eagerly devoured. among them were _robinson crusoe_, _gulliver's travels_--both never so familiar in scotland to boys as they are in england--cook's _voyages_, john howie of lochgoin's _worthies_, the _voyages_ of anson, drake, raleigh, dampier, and byron, 'my grand-dad's narrative' of the poet. it was not till his tenth year that he became, as he says, 'thoroughly a scot,' and this was effected by a perusal of blind harry's _wallace_, that 'bible of the scottish people,' as lord hailes has called it, following or anticipating the remark by wolf as to the similar position of the _iliad_ and the _odyssey_ among the greeks. no one now need be informed about the influence that quaint old work had produced in burns, and through him on the subsequent re-awakening of the national spirit at the end of the eighteenth century. barbour's _bruce_ has remained the possession of the scholar and the antiquary, while this work of the old minstrel, literally 'sung by himself for small earnings and good cheer, at festivals and other days of merriment,' as bentley had said of his great predecessor, has had an abiding influence on literature, and on the national character. 'up to crummade (cromarty) and through the northland' had blind harry, with a fine patriotism, and, we fear, a total disregard for geography, made his hero effect a raid. when a man has got a view from dan to beersheba in which to smite the enemy hip and thigh, he need not be troubled with a few outlying counties. the parish school of cromarty which miller attended numbered about a hundred and twenty boys and girls. the windows of the building fronted the opening of the cromarty firth, recalling at least by 'the mystery of the ships' the portland of longfellow's own early days. the tax of twenty peats to the school from the highland boatmen paid for every boat in the trade recalls the salary of the public hangman of inverness and aberdeen, and the dues often formed the subject of debate between the boys and the irate gaels, who did not fail to retort the taunt of the hangman's perquisite. the schoolmaster was a worthy that might have sat for the figure of jonathan tawse in dr. alexander's _johnny gibb_, and was, though a fair scholar, rather inefficient as a disciplinarian and teacher. yet it was his boast--one now, alas, in these days sadly becoming obsolete--that he sent forward more lads to the bursary competition at the northern university than any other teacher, and his 'heavy class' of a few boys in latin was increased by his persuading the willing uncle james to set miller to the _rudiments_ in that time-honoured volume by ruddiman, who had in his own days been a first bursar at aberdeen. the teaching of latin had been one of the props to education introduced by the reformers, and so distinct had been the little note of pedantry, perhaps in this way fostered, that smollett makes the barber in _roderick random_ quote horace in the original, and foote in a farce has made a valet insist on its possession as a shibboleth of nationality. we need but mention the favourite quotations in the ancient tongue by the baron of bradwardine and dugald dalgetty as a reminiscence of his own old days 'at the marischal college'; while miller also could remember an old cabinet-maker who carried for the sake of the big print a latin new testament to church. but no more with him than with darwin could the linguistic faculty be stimulated. the _rudiments_ he thought the dullest book he had ever seen, and though in after-life he regretted the lost opportunity that at five-and-twenty might have made him a scholar and thus have saved ten of the best working years of his life, it may be doubted if in his case the loss amounted to more than in the case of macaulay, who affected to bewail his loss of mathematics. in their truest form, scholars, like naturalists, are born and not made, nor will any labour in the linguistic field yield much to the scientist. the poet gray wisely lamented the loss of time in his own case through forced labour at mathematics, a remark not even yet fully appreciated in scotland, where the system of general excellence--that system under which johnson so happily remarked that, while each man got a bite, no one got a bellyful--has too long stunted the learning of the country and proved the bane alike of her schools and universities. 'as for latin, i abominate it,' we find him writing from cromarty in december , in a letter now before us, 'and ever did since i burnt my _rudiments_.' more congenial amusement he found in the exercise of his story-telling faculty. when the master's back was turned, the _sennachie_, as the master called him, would gather round him the other boys and narrate to them the adventures of his uncle, the story of gulliver, and the shipwreck of robinson crusoe, or even the mysteries of mrs. radcliffe. when the sixty volumes of his father and the hundred and sixty of his uncles had been consumed, he fell in with a collection of essayists from addison to henry mackenzie, the influence of which, along with goldsmith's _citizen of the world_, remained to the last as a powerful impress upon his prose style. but he was rapidly finding his national and true school. the hill of cromarty, part of de beaumont's ben-nevis system, and the rich liassic deposit of eathie, were his favourite haunts, and his uncle alexander, after his own work was done, would spend with him many an hour in the ebb tide. to the training thus acquired from this untaught naturalist he owed much of his own close powers of observation, which led, however, well-nigh to a fatal termination through an adventurous visit to the doo-cot caves, from which he was rescued late at night during a high tide. this formed the subject of his first copy of juvenile verse, which was recited 'with vast applause' by the handsomest girl at the cromarty boarding establishment kept by miss elizabeth bond. in her own early days she had known the father and mother of scott; and, when in she had published her _letters of a village governess_, she had dedicated them to the great novelist, who later on in the midst of his own troubles, living in lodgings away from abbotsford, could yet remember to send her ten pounds 'to scare the wolf from the door,' as he cheerily remarked, when she had found the truth of her own saying that it was hard for a single woman to get through the world 'without a head'--unmarried. his reading at this time received a curious extension through there falling into his hands a copy of _military medley_ belonging to a retired officer, and on the shore he would carry out plans of fortification as therein set forth by the great french engineer vauban. with sand for towers, and variegated shells and limpets for soldiers, he worked his way through the evolutions of troops, and no reader of scott will fail to remember the similar action by sir walter which, in the introduction to the third canto of _marmion_, he describes as taking place at sandy knowe, in the air of the cheviots, near the old tower of smailholme that 'charmed his fancy's waking hour':-- 'again i fought each combat o'er, pebbles and shells in order laid the mimic ranks of war displayed.' nor will he fail to note the exact and characteristic point of difference in the two children, and how in each the child was father of the man. so early in both was the natural instinct of the future historian and the geologist awakened. at a later period he seems rather to have become an unruly lad, and to have proved too much for his relations to manage. he was in the stage when such boys run away to sea or enlist, and his father's own calling might, from its well-nigh hereditary nature, have been thought to be the one most likely to be adopted. he enjoyed a somewhat dangerous reputation through carrying a knife and stabbing a companion in the thigh, but these escapades may in later years have been unconsciously heightened by remorse for wasted opportunities, and which in his case we have seen to amount to little or nothing. but the circle of his own companions was changing or breaking up, and it became necessary to decide on the future. his mother, after being a widow for well-nigh a dozen years, had married again, and he determined on being a mason, an occupation which he thought would, by his being employed in labour at intermittent seasons, afford him plenty leisure. against this resolution both his uncles stoutly protested, and were prepared to assist him to the northern university. 'i had no wish,' he says, 'and no peculiar fitness to be either lawyer or doctor; and as for the church, that was too serious a direction to look in for one's bread, unless one could necessarily regard one's-self as called to the church's proper work, and i could not.' his uncles agreed to this view of the case; and so, reluctantly, the proposed course was abandoned. 'better be anything,' they said, 'than an _uncalled_ minister.' his was not the feeble sense of fitness possessed in such a high degree by the presentees to auchterarder and marnoch. as a member of the moray nation he would naturally have proceeded to king's college in aberdeen, then at the very lowest ebb of its existence as regards the abilities, or the want of them, of the wondrous corps of professors who filled its chairs. carlyle in his _sartor_ has drawn certainly no flattering picture of the edinburgh of his days, and his friend professor masson in the early volumes of _macmillan's magazine_ has put before us the no less wonderful spectacle of the marischal college of his own student life; nor would the state of king's college about yield much material for respect. the professoriate was grossly ignorant and conceited, and nepotism was rampant. as a child, we can recall the last expiring flicker of the race, and when we add that one aspiring graduate had published a pamphlet to refute newton, and that the theology was of the wintriest type of even aberdonian moderatism, couched in the most remote imitation of the rhetorical flights in _the man of feeling_, we have said enough to show that miller certainly lost nothing by non-attendance at the classes in aberdeen. but it was not without reluctance that his resolve to become a mason was allowed by his uncles. however, at last, there being another uncle on the mother's side who was a mason contracting for small jobs, and who employed an apprentice or two, he was bound apprentice for three years, from february to november and entered on the trade of mason and quarryman, for in the north the combination was constant. long after, in the _old red sandstone_ he has described his first day's experience in the sandstone quarry, when, in that early spring morning and with a heavy heart, he set out to experience his first battle in the stern school of the world: 'i was but a slim, loose-jointed boy at the time, fond of the pretty intangibilities of romance, and of dreaming when broad awake; and, woful change! i was now going to work at what burns has instanced in his _twa dogs_ as one of the most disagreeable of all employments. bating the passing uneasiness occasioned by a few gloomy anticipations, the portion of my life which had already gone by had been happy beyond the common lot. i had been a wanderer among rocks and woods--a reader of curious books when i could get them--a gleaner of old traditional stories; and now i was going to exchange all my day-dreams and all my amusements for the kind of life in which men toil every day that they may be enabled to eat, and eat every day that they may be enabled to toil. the quarry in which i wrought lay on the southern shore of a noble inland bay, or firth rather (the bay of cromarty), with a little clear stream on the one side and a thick fir wood on the other. it had been opened in the old red sandstone of the district, and was overtopped by a huge bank of diluvial clay, and which rose over it in some places to the height of nearly thirty feet.' he was to experience constant fits of depression and exhaustion, which caused sleep-walking; and though this after a time passed away, it was yet in later years to recur with fatal effects. in his master he was fortunate. he was one who would fully have come up to carlyle's standard of his own father, 'making a conscience of every stone he laid.' unconsciously, also, the apprentice was laying the foundations of the educated sense of sight so essential to the mason, and which was to stand him in excellent service in later years of geological ramblings. but the life was a hard one, from the surroundings in which the trade of a north-country mason had to be carried on. living in a small village, where the lack of steady employment was naturally often felt, he had to eke out a living by odd jobs in the country, building farm-steadings or outhouses, with but scanty shelter and in surroundings too often unfavourable to comfort or morality. his experience of the bothy-system thus acquired by personal hardship he was in later years to turn to account in his leaders in _the witness_--'i have lived,' he says, 'in hovels that were invariably flooded in wet weather by the over-flowings of neighbouring swamps, and through whose roofs i could tell the hour at night, by marking from my bed the stars that were passing over the openings along the ridge.' he was now to feel the truth of his uncles' warnings in dissuading him from the occupation. they had pointed to a hovel on a laird's property, who had left it standing that at some future date it might be turned to profit when he should have a drove of swine, or when a 'squad' of masons would pass that way. the life which had been introduced by the large farm system had been criticised already by burns, who in the jottings of his _highland tour_ had been struck by the superior intelligence of the ayrshire cottar to the stolid boorishness of the agricultural labourer in the districts of the lothians and the merse. recent legislation has largely mitigated the evils of the system which, even in a higher scale of comfort, has received a stern indictment in the eighth chapter of dr. william alexander's excellent work which we have before quoted, and to which, as the classic of the movement with which miller's life is associated, we shall again refer. 'better,' said cobbett, who had studied it during a brief sojourn in the country, 'the fire-raisings of kent than the bothy system of scotland.' even geological rambles and communings with the muse afforded but scant alleviation of the hardships endured. during rainy weather the food would often be oatmeal eaten raw, at times with no salt save from a passing highland smuggler, or consist of hastily prepared gruel or _brochan_. in time he learned to be a fair plain cook and baker, so as at least to satisfy the demands of the failing teeth of his old master. accordingly, he was not sorry when the three years of his apprenticeship closed, and as a skilled labourer he could retire about the martinmas of to cromarty, where his first piece of work was a cottage built with his own hands for his aunt. in he was with a working party at gairloch, and was there for the last time to experience the discomforts in the life of the working mason when employed by a niggard highland laird. forced from the barn in which they were at first domiciled into a cow-house to make room for the hay, they found themselves called upon to convert the materials of this hovel into the new building upon which they were engaged. this they effected by demolishing the entrance gradually, and hanging mats over it, leaving themselves ultimately to the cold october wind which not even miller's experiences as a boy of the caves in the sutors of cromarty could render tolerable. but he had begun to see that the sphere of constant employment was narrow and narrowing in his native place, and, as the building mania in the south at the time seemed to afford a better opening for a steady workman, to edinburgh accordingly he resolved to betake himself. there was the additional reason in a desire to free the family from the burden of a house on the coalhill of leith, which had long before fallen to his father through the legacy of a relative, and which had threatened, through legal expenses, lack of tenants, and depreciated value, to become a serious legacy indeed. the parish church of north leith had been erected, and he had been rated as a heritor for a sum so considerable that the entire year's rental of the dilapidated tenement was swallowed up, together with most of his savings as a mason. he had come of age when in the miserable hovel at gairloch we have described, and was now competent to deal with his luckless property. setting sail in the leith smack running between cromarty and that port, he entered the firth of forth four days after losing sight of the sutors. he saw with interest dunottar castle and the bass rock chronicled in the well-known lines of his friend, dr. longmuir of aberdeen. indeed the latter had for him peculiar associations through one of the ross-shire worthies in the times of charles ii.--james fraser of brea;--for, when the sun set on the upland farm on which he had been born, miller knew that it was time to collect his tools at the end of his day's labour. in , when he visited the rock on the geological expedition which he has commemorated by his paper on the structure of the bass, his thoughts again reverted to fraser, and to two other captives from his own district, mackilligen of alness and hog of kiltearn. his uncle james had at an early period introduced him to burns and fergusson, while from his boyish days the old novel of smollett, _humphrey clinker_, had been no less familiar than from the pages of _david copperfield_ we know it to have been to dickens. it was, therefore, with no small interest that he caught his first view of arthur seat and the masts of the shipping in the harbour of leith. it was still the veritable auld reekie' of fergusson, preserving its quaint distinctiveness by the happy blending of the divisions of the old town and the new--the old town through which, says lockhart, the carriage of scott would creep at the slowest of paces, driven by the most tactful and discriminating of jehus, while every gable and buttress in what a recent prosaic english guide-book denominates the most dilapidated street in europe would crowd its storied memories upon the novelist and poet of the _chronicles of the canongate_. to the last, like carlyle, he preserved the memory, ever a landmark to the patriotic scot, of his first day in the old 'romantic town' of sir walter, and of his impressions of the most picturesque of european capitals. chapter ii in edinburgh--the cromarty bank 'i view yon empress of the north sit on her hilly throne.' scott. he had not long to experience what gilbert burns said was to his brother the saddest of all sights, that of a man seeking work. he had called on the town-clerk to see whether some means could be devised of setting himself free from the property when, on mentioning his occupation, he was not only told the prospect of a sale was not so hopeless as he had expected, but was introduced to a builder erecting a mansion-house in the south of edinburgh. he lodged in the village of niddry mill, and found his experience of life among metropolitan labourers the very reverse of favourable. his not very high opinion of the working classes, for, as we shall see, miller remained a whig to the last with a wholesome horror for radicals and chartists, was doubtless due to the circumstances under which he found himself, and not to any feeling of superiority on his part. the social condition of the working classes was then on the eve of transition, and the organisation of even skilled labour was but in a rudimentary condition. in edinburgh at least, the better class of mechanics sought within the walls of the city a more remunerative sphere for their labour, so that it was only the inferior body of workmen that was found on the outskirts. at first, he was subjected to a good deal of low and petty tyranny from his fellow-labourers, which was not calculated to improve his opinion of the class. some slight relief, however, he managed to find in the new geological surroundings--the carboniferous deposits--and by observation and theory he made his way to some good results in his own science, at a time when there was no map, manual, or even geological primer in existence. the policies of niddry and walks in the ruins of craigmillar were a solace from the drunken and intemperate habits of the men, whose forty-eight shillings for the fortnight's wage were soon consumed by sunday drives to roslin or hawthornden, or by drinking bouts in the lower rookeries of the high street. there still largely prevailed the convivial habits such as fergusson has described as characteristic of the edinburgh of his day, the tavern 'jinks' alluded to by scott in _guy mannering_, and by lockhart in his _life of burns_. in the taverns the landlords kept a cockpit or a badger as a necessary part of their attraction. employment being constant through the pressure of the building mania prevalent throughout this year, the masters were largely at the mercy of the men, so that strikes were rife and the demands of the workers exorbitant. altogether it was no favourable school for miller to learn regard for his own class. again and again, to the end, do we find not undeserved denunciations of the dangers of chartism, and his own reiterated belief that for the skilled workman there is no danger, and for the thriftless no hope. the collier villages round niddry have long since disappeared. the seams have for all practical purposes been worked out, or have been given up as unprofitable. there he found the last surviving remains of slavery in scotland, for the older men of the place, though born and bred 'within a mile of edinburgh toun,' had yet been born slaves. the modern reader will find much curious information upon this subject in erskine's _institutes_; but, in passing, we may recall the fact that sir walter scott has mentioned the case of scott of harden and his lady, who had rescued by law a tumbling-girl who had been sold by her parents to a travelling mountebank, and who was set at liberty after an appeal to the lords, against the decision of the chancellor. scott was assoilzied; but, even as late as , an act of parliament had to be passed dealing specially with this last remnant of feudal slavery--the salters and the colliers of scotland. the old family of the setons of winton had, along with others, exercised great political influence and pressure on the court of session, and had repeatedly managed to defeat or evade measures of reform. a law had even been passed enacting that no collier or salter, without a certificate from his last place, could find work, but should be held as a thief and punished as such, while a later ordinance was that, as they 'lay from their work at pasche, yule and whitsunday, to the great offence of god _and prejudice of their masters_,' they should work every day in the week except at christmas! clearly there was no eight hours bill in old scotland. his lodging was a humble one-roomed cottage in niddry, owned by an old farm-servant and his wife. the husband, when too old for work, had been discharged by his master, whose munificence had gone the length of allowing residence in the dilapidated building, on the understanding that he was not to be held liable for repairs. the thatch was repaired by mud and turf gathered from the roadside, and in this crazy tenement the old man and his wife, both of whom had passed through the world without picking up hardly a single idea, were exposed to the biting east winds of the district. a congenial fellow-lodger was fortunately found in the person of another workman, one of the old seceders, deep in the theology of boston and rutherfurd, and such works as had formed the reading of his uncles in cromarty, for at this time the sense of religion, at least among the humbler classes, was well-nigh confined to the ranks of dissent. many of the inhabitants of the place were or had been nominal parishioners of 'jupiter' carlyle of inveresk. but the doctor had not been one to do much for the social or religious advance of his people. jupiter, or 'old tonans,' as he was called from sitting to gavin hamilton the painter for his portrait of jupiter, had been the fanatical defender of the theatre at a time when his friend john home, the writer of _douglas_, had been compelled by public opinion to seek relief from pulpit duties, and a more fitting sphere for his rants of 'young norval on the grampian hills' in the ranks of the laity. carlyle and his friend dr. hugh blair were constant patrons of the legitimate drama in the old playhouse in the canongate, when the burghers at night would 'dauner hame wi' lass and lantern' after the manner described with such power by scott in the tolbooth scene of _rob roy_. on one occasion, the doctor had, for once in his long life, to play the part of non-intrusionist, when he repelled vigorously with a bludgeon the attempt of some wild sparks to force an entry into his box! missions he denounced in the spirit of a fanatical supporter of the repressive régime of pitt and dundas. he trusted to the coming of christ's kingdom by some lucky accident or sleight of hand, 'as we are informed it shall be in the course of providence.' he had no belief in 'a plan which has been well styled visionary.' in the closing years of his own life, the very slight modicum of zeal for the discharge of his ministerial duties ebbed so low that he left these entirely to an assistant, and spent the sunday on the musselburgh race-course. yet this is the man whom dean stanley with exquisite infelicity selects as one of the heroes of the church of scotland. in the picture of old 'jupiter' there is something that recalls the belief of the erratic lord brougham, when he voted against the veto act and the right to protest against unsuitable presentees, from fear that it might end in 'rejecting men too strict in morals and too diligent in duty to please our vitiated tastes!' carlyle's _autobiography_ is one of the most instructive of books; like the similar disclosure by benvenuto cellini, it is the presentation of a man who is destitute of a moral sense. although in the pulpits of the metropolis moderatism was but only too well represented, there were yet some striking exceptions. sir walter scott, whose feelings led him strongly in the direction of the latitudinarian party, has yet drawn in _guy mannering_ an admirable sketch of dr. john erskine, the colleague of principal robertson in the greyfriars, and for long the leader of the evangelical party in the church of scotland. some of the members of that party were gladly heard by miller, but his greatest delight he confesses to have been in hearing the discourses of the old seceder, dr. thomas m'crie. 'be sure,' said his uncles to him on leaving cromarty, 'and go to hear m'crie.' the doctor was no master of rhetoric or of pulpit eloquence, but the doctrine was the theology of the true descendant of the men of drumclog and bothwell. nothing is more characteristic of the university system of scotland than that the greatest ecclesiastical scholar she could produce was to be found in a humble seceding chapel at the foot of carrubber's close. in scotland, at least within the present century, no more influential book has been published than his _life of knox_, which silently made its appearance in . in the revival of ecclesiastical and national feeling in the country the book will ever remain a classic and a landmark. there it occupies the place which, in the field of classical and historical scholarship, is taken by wolf's _prolegomena to homer_. lord jeffrey could truly declare that to fit one's-self for the task of even a reviewer of m'crie, the special reading of several years would be necessary. its influence was at once felt. the 'solemn sneer' of the humes, gibbons, robertsons, and tytlers, and, be it mentioned with regret, of even scott in that unworthy squib against the religion of his country, _old mortality_, had done much, at least among the _literati_ and the upper classes, to obliterate and sap a belief or knowledge of the great work which had been accomplished for civil liberty by the early reformers; but now the school of flimsy devotees of mary, montrose and claverhouse, with its unctuous retention of the sneer (or, historically meant, compliment) of the merry monarch as to presbyterianism being no fit religion for a gentleman, the school whose expiring flicker is seen in aytoun's _lays of the scottish cavaliers_, was for ever exploded by the research of m'crie. it was in an unlucky hour that scott ventured a reply to the strictures of his reviewer. never was humiliation more deep or more bitterly felt by the novelist. the novel of scott is about as gross a caricature as 'carrion' heath's _life_ of oliver cromwell, and for the historical restoration of the great reformer, m'crie has done in his book what carlyle, in his _letters of cromwell_, has for ever effected for the true presentation of the protector. in the bookstalls of the city he would pick up some new additions to his shelf. at odd hours, too, he would hang about castle street in the hope of seeing sir walter scott. the capital at this time, though sadly shorn of its old literary coteries in the days of burns, still numbered such men as jeffrey, cockburn, dugald stewart, and professor wilson; and he did manage, one evening, to spend some hours with a cousin in ambrose's, where the famous club used to hold their meetings in a room below. but none of these faces was he then destined to know in the flesh, and the 'pride of all scotsmen' whom carlyle met in the edinburgh streets, 'worn with care, the joy all fled,' had passed away the next time when miller visited the capital. work, we have seen, was plentiful in the town. the great fire had swept parliament close and the high street, carrying with it the steeple of the old tron, and many of the lofty tenements that formed such a feature of old edinburgh. but he was feeling the first effects of the stone-cutters' disease, and his lungs, affected by the stone dust, threatened consumption. he states that few of his class reached the age of forty through the trouble, and not more than one in fifty ever came to forty-five. but circumstances fortunately enabled him at this critical juncture to leave work for a time. the house on the coalhill had turned out better than was expected, and, with a clear balance of fifty pounds in his pocket, he could set sail for cromarty, where, after a weary seven days' voyage through fog and mist, he was met on landing by his uncles. not for ten years, and then under very different circumstances, was he again to see edinburgh. during this period of convalescence he experienced a religious change, leading to positions from which he never saw reason to recede. 'it is,' he says, 'at once delicate and dangerous to speak of one's own spiritual condition, or of the emotional sentiments on which one's conclusions regarding it are so often doubtfully founded. egotism in the religious form is perhaps more tolerated than any other, but it is not on that account less perilous to the egotist himself. there need be, however, less delicacy in speaking of one's beliefs than of one's feelings.' this last remark is eminently characteristic at once of the individual and of the national type of severe reticence on internal religious experience. this may serve to throw some light on the taunt flung by dr. johnson, in one of his most boisterous moods in skye, at the head of boswell. 'can you,' he asked, 'name one book of any value on a religious subject written by the scottish clergy?' johnson does not seem to be dwelling on specifically theological works; he has rather in his mind the manuals of a homiletic or devotional order, in which he rather wildly asserts 'the clergy of england to have produced the most valuable works in theory and practice.' it might fairly have been retorted on johnson that, were this so, the physicians at least had ministered but poorly to themselves, by quoting to him his own remark that he had never once met with a sincerely religious english clergyman; but bozzy, patriotic for once, fell upon the defence of faithful discharge of pulpit ministrations and poor endowments. it might have been wiser to have fallen back on the long and militant struggle of the church of scotland for her existence, wiser still to have based the defence on national and psychological grounds. nothing in the scottish character is more remarkable than the absence of the feeling that led luther and wesley to a constant introspection, or at least to its frank outward expression and effusive declaration of their spiritual state. some little knowledge of this national trait we think would have saved much windy and remote declamation about fanaticism, gloomy austerity, and enthusiasm--that mental bugbear of the eighteenth century, and well-nigh sole theological stock-in-trade of the gentlemanly and affected school of hume and robertson. the absence of anything like mysticism either in the nation or in its theology has been, therefore, unfavourable to the appearance of any cheap or verbal pietism. calvinism, it may be added, is poor in comparison with lutheranism, poorer still when contrasted in this respect with the roman church; for, while the former has behmen and swedenborg, and the latter many names such as guyon and rosmini among a host, scotland has nothing of this kind, unless in the case of erskine of linlathen or campbell of row. the reason for this would seem to be that calvinism has both a religious and a political side. as a philosophic creed, at least in details, it affords a completeness of presentation that leaves no room or indeed desire to pass behind the veil and dwell on the unknowable and the unknown. miller, at all events, found that hitherto his life had lacked a 'central sun,' as he expresses it, round which his feelings and intellect could anchor themselves. this he found by a curiously instructive combination of historical and geological reasoning. professor blackie has pointed out that the true secret of the vitality of the old paganism and its logical internal consistency simply lay in the fact of the great humanity of the deities it created. this, also, as miller himself no less clearly shows, is at the bottom of the enduring element in the lower reaches of catholicism. 'there is,' says our scottish neander, rabbi john duncan, 'an old cross stone of granite by the roadside as you wind up the hill at old buda, in hungary, upon which a worn and defaced image of our saviour is cut, which i used often to pass. the thorough woebegoneness of that image used to haunt me long--that old bit of granite, the ideal of human sorrow, weakness and woebegoneness. to this day it will come back before me--always with that dumb gaze of perfect calmness--no complaining--the picture of meek and mute suffering. i am a protestant and dislike image-worship, yet never can i get that statue out of my mind.' this, then, to miller formed the 'central sun'--'the word made flesh;' not merely as a received mental doctrine, but as a fact laid hold of, and round which other facts find their true position and explanation. 'there may be,' he allows, 'men who, through a peculiar idiosyncrasy of constitution, are capable of loving, after a sort, a mere abstract god, unseen and unconceivable; though, as shown by the air of sickly sentimentality borne by almost all that has been said and written on the subject, the feeling in its true form must be a very rare and exceptional one. in all my experience of men i never knew a genuine instance of it. the love of an abstract god seems to be as little natural to the ordinary human constitution as the love of an abstract sun or planet.' no less interesting are his arguments from the geological position. it was a difficulty which had long lain heavy on the mind of byron when, the reader may remember, in his last days in he beat over much theological and metaphysical jungle with the scottish doctor kennedy--the greatness of the universe and the littleness of the paragon of animals man, and the consequent difficulty of satisfactorily allowing a redemptive movement in heaven for man in all his petty weakness. pascal had attempted to meet this by what hallam calls 'a magnificent lamentation' and by a metaphysical subtlety, reasoning from this very smallness to his ultimate greatness. but the geological reasoning of miller has the undoubted merit of being scientific and inductive. in geology the dominant note is, in one word, progress. 'there was a time in our planet,' and it will be noted that the argument is perfectly independent of the appearance of man, late with himself, early with lyell, 'when only dead matter appeared, after which plants and animals of a lower order were made manifest. after ages of vast extent the inorganic yielded to the organic, and the human period began,--man, a fellow-worker with the creator who first produced it. and of the identity of at least his intellect with that of his maker, and, of consequence, of the integrity of the revelation which declares that he was created in god's own image, we have direct evidence in his ability of not only conceiving of god's own contrivances, but even of reproducing them, and this not as a mere imitator, but as an original thinker.' man thus, as hegel says, re-thinks creation. but higher yet the tide of empire takes its way. the geologist is not like the neapolitan thinker, vico, with his doctrine of recurring cycles in man. the geologist 'finds no example of dynasties once passed away again returning. there has been no repetition of the dynasty of the fish--of the reptile--of the mammal. the long ascending line from dead matter to man has been a progress godwards--not an asymptotical progress, but destined from the first to furnish a point of union; and occupying that point as true god and true man, as creator and created, we recognise the adorable monarch of all the future.' such an argument is indeed a reach above the vaguely declamatory theory of swinburne of man being the master of all things, and above the theory of feuerbach that finds god merely in the enlarged shadow projected by the ego. his somewhat impaired strength led him to think of a livelihood through little jobs of monumental stonework in a style superior to that introduced as yet into the countryside, and to this period of observation of the scottish character acquired through living in the vicinity of farm-houses, villages, churchyards, as the varying means of lodging were afforded him, he ascribed much of the knowledge which he turned to so good an editorial account. in the company, too, of the parish minister stewart he was happy, for, according to his own conviction and the testimony of many others, he was a man of no ordinary acuteness and of unquestioned pulpit ability. indeed, miller never hesitated to declare that for the fibre of his whole thinking he was more indebted to chalmers and to this almost unknown cromarty minister than to any two other men. stewart's power seems to have lain in the detection of subtle analogies and in pictorial verbal power, in which he resembled guthrie. in an obituary notice in _the witness_ of nov. , he dwells with affection on the man, and illustrates admirably the type of intellect and its dangers. 'goldsmith,' he observes, 'when he first entered upon his literary career, found that all the good things on the side of truth had been already said; and that _his_ good things, if he really desired to produce any, would require all to be said on the side of paradox and error. poor edward irving formed a melancholy illustration of this species of originality. his stock of striking things on the side of truth was soon expended; notoriety had meanwhile become as essential to his comfort as ardent spirits to that of the dram-drinker; and so, to procure the supply of the unwholesome pabulum, without which he could not exist, he launched into a perilous ocean of heterodoxy and extravagance, and made shipwreck of his faith. stewart's originality was not the originality of opening up new vistas in which all was unfamiliar, simply because the direction in which they led was one in which men's thought had no occasion to travel and no business to perform. it was the greatly higher ability of enabling men to see new and unwonted objects in old familiar directions.' for sixteen years miller sat under his ministry, and for twelve was admitted to his closest intimacy. but in time work of even the 'old mortality' order grew scarce. accordingly, in the summer of june , he visited inverness, and inserted in the local papers an advertisement for employment. he felt that he could execute such commissions with greater care and exactness than were usual, and in a style that could be depended upon for correct spelling. he mentions himself the case of the english mason who mangled proverbs xxxi. into the bewildering abbreviation that 'a virtuous woman is s. to her husband,' and he might also have mentioned the case of the statue to george ii. in stephen's green, dublin, erected doubtless under municipal supervision, and which yet in the course of a brief latin inscription of thirteen lines can show more than one mistake to the individual line. he had the curious, yet perhaps after all not unpractical, idea that his scheme for employment might be materially improved by his sending a copy of verses to the paper, in the belief that the public would infer that the writer of correct verse could be a reliable workman. but nothing came of this. in justice to the editor it may be allowed that the versification, if easy, was nothing remarkable, and felicity of epithets may be no guarantee for perfection of epitaphs. the reflection, however, came to him that there was no advantage to be won in thus, as he says, scheming himself into employment. it was not congenial, and walking 'half an inch taller' along the streets on the strength of this resolution, he was actually offered the queen's shilling, or the king's to be chronologically correct, by a smart recruiting sergeant of a highland regiment who from the powerful physique of the man had naturally inferred the possession of a choice recruit. he determined, accordingly, to face the worst and publish. he made a hasty selection of his verses through the last six years and approached the office of the _inverness courier_. this was a highly fortunate opening, for that paper was, then and up to , edited by robert carruthers of dumfries, who had been appointed editor of the _courier_ in the very same year of miller's visit. his _life of pope_ published in is still a standard production, and altogether carruthers was one of the ablest editors in scotland, and his paper which was edited on liberal lines was a very powerful organ in his day. the friendship then begun lasted till the death of miller unbroken, and was mutually advantageous. while he was still in the highland capital he received word of the fatal illness of his uncle james, and his first work on his return was a neat tombstone for this close friend of his father and worthy to whom he was so deeply indebted for much of his own subsequent distinction. his volume of verse under the title of _poems written in the leisure hours of a journeyman mason_ issued slowly in from the press, and its appearance in the disillusionising medium of black and white convinced him that after all his true vocation was not to be found in poetry, for many lines which had appeared as tolerable, if not more, to the writer in the process of composition were now robbed of their charm by commission to print. indeed, at no time does his versification rise beyond fluent description. it lacks body and form, and was really in his case nothing but a sort of rudimentary stratum on which he was to rear a very strong and powerful prose style. he was lacking in ear, and he confessed to an organ that recognised with difficulty the difference of the bagpipe and the big drum. the critics were not very partial to the venture. the tone of the majority was that of the _quarterly_ upon keats, and the autocrats of poetical merit declared that he was safer with his chisel than on parnassus. one little oasis, however, in the desert of depreciation did manage to reach him in a letter, through his friend forsyth of elgin, from thomas pringle of roxburgh who had seen the book. in early days the poet had been a clerk in the register house of edinburgh, where his _scenes of teviotdale_ had secured him an introduction to scott, who extended to him the same ready support which he had bestowed on leyden. by his influence he was appointed editor of _blackwood's magazine_, and later on emigrated with a party of relatives to the cape, where his unsparing denunciations of the colonial policy in its treatment of the natives, and his advocacy of what would now be called the anti-rhodes party brought him into complications with the officials in downing street and the colonial authorities. poor pringle!--among the one-song writers, the singers of the one lilt that rises out of a mass of now forgotten verse, his name is high, and he has won for himself an abiding niche in the hearts of his countrymen by his _emigrant's lament_, where he touches with a faultless hand the scenery of 'bonnie teviotdale and cheviot mountains blue.' the volume of verses was not without its more immediate results in a local circle. it brought him under the notice of sir thomas dick lauder of relugas, who is now remembered by his _wolf of badenoch_--a not quite unsuccessful effort at bending the bow of ulysses, though without the dramatic force of scott. by carruthers he was introduced to principal baird, and thus a link with the past was effected through a man who had edited the poems of michael bruce, had befriended alexander murray for a short period the occupant of the oriental chair in edinburgh, and been a patron of pringle and a close friend of scott. by baird he was strongly pressed to venture on a literary life in the capital, but the time was not propitious, and he wisely resolved to devote himself to several years of accumulation and reflection before he should embark on a vocation for which he had no great liking, and in which, even to the last, he had but little belief. for an ordinary journalist he would indeed have been as little qualified as burns when offered a post on perry's _morning chronicle_. the justness of his resolution was fully shown when the opportunity found him, and he was then fully prepared for the work he was to do. he was induced by the principal to draw up for him a brief sketch of his life, and of this a draft bringing it up to was composed and sent to edinburgh. there existed at this time in the north the remains of a little coterie of ladies, numbering among its members henry mackenzie's cousin,--mrs. rose of kilravock, whom burns had visited on his highland tour, lady gordon cumming, and mrs. grant of laggan, whose once well-known _letters from the mountains_ have yielded in popularity to her song of _highland laddie_, which commemorates the departure in of the marquis of huntly with sir ralph abercromby. by none of them, however, was he more noticed than by miss dunbar of boath, who occupies in his early correspondence the place taken in the letters of burns by mrs. dunlop. during his visits to this excellent lady he explored the curious sand-dunes of culbin which still arrest the attention of the geologist and traveller in his rambles by the findhorn. by miss dunbar he was pressed to embark on literature, while mrs. grant was of the opinion that he might follow the example of allan cunningham, who was engaged in the studio of chantrey. but such patronage was in his case no less wisely exercised than admitted, nor was his the nature to be in any way spoiled by it; his self-reliant disposition suffered no such baneful effects as were felt by the much weaker nature of thom of inverurie, the one lyrical utterance of aberdeenshire, or by burns in the excitement of his edinburgh season. he even became a town councillor, though he admits that his masterly inactivity was such as led him to absent himself pretty wholly from the duties, whose onerous nature may be inferred when the most important business before the council was, on one occasion, clubbing together a penny each to pay a ninepenny postage in the complete absence of town funds. into his life at this period a new vision was introduced through the appearance on the scene of a young lady whom he was afterwards to make his wife. sauntering through the wood on the hill overlooking the cromarty firth he met miss lydia fraser, who was engaged in reading 'an elaborate essay on causation.' the reader may remember--with feelings, we hope, of contrition for mr. lang's railway lyric on the _fin de siècle_ students of miss braddon and gaboriau, and for the degenerate tendencies of the age,--the curiously fitting parallel in which the geologist buckland met in a devonshire coach, his future wife, miss morland, deep in a ponderous and recently issued folio of cuvier, into which even he himself had not found time to dip! miller was ten years the senior of his young friend, whose father had been in business in inverness, and whose mother had retired to cromarty to live in a retired way upon a small annuity, added to by her daughter's private pupils. as a girl miss fraser had been a boarder in the family of george thomson, whose _select collection of original scottish airs_, enriched by the hand of burns with about a hundred songs, forms an abiding monument of their joint taste and judgment. the acquaintance ripened into intimacy and an agreement that for three years they were to make scotland their home, when, should nothing then turn up they were to emigrate and try their fortune in america. but fortunately an opening occurred which was to retain him at home for the work he was so naturally fitted to perform. cromarty had hitherto been without a bank. now, through the representation of local landowners and traders, the commercial bank of scotland was induced to extend one of its branches to the town. the services of a local shipowner were secured for the post of agent, and miller was offered the place of accountant. it was necessary, of course, that he should qualify himself for his new duties, and so he sailed to leith to acquire his initiation at linlithgow. he was now in his thirty-second year. before leaving cromarty he had been engaged upon his _scenes and legends_ of the traditional history of the country, and on his forwarding his manuscript to sir thomas dick lauder, to whom it is dedicated, he was invited by the hospitable baronet to meet mr. adam black the publisher, whose long retention of the copyright of the waverley novels has shed distinction on the firm of which he was the head. by him very generous terms were offered, and miller by his venture realised £ over his second book, which still seems to enjoy in its thirteenth edition no slight share of popularity. he was even pressed by sir thomas to make his own house at grange his residence while in the south, but, linlithgow having been already fixed upon he took his passage in the fly-boat running on the canal between edinburgh and glasgow and soon 'reached the fine old burgh as the brief winter day was coming to a close, and was seated next morning at my desk, not a hundred yards from the spot on which hamilton of bothwellhaugh had taken his stand when he shot the good regent.' at first he was rather diffident of his ability for the work, the swiftness of mechanical summation never to the end coming to him perfectly natural; though, in the course of a brief two months' absence from cromarty, he was able to join the bank with such a working acquaintance with the details of the business that, when the policy of sir robert peel threatened an attack upon the circulation of the one-pound note, he was competent to publish a series of articles, _words of warning to the people of scotland_, in which he defended the cash credit system of scottish banking. this had before been fully expounded by hume and scott, and miller could show its peculiar ability for enabling men to 'coin their characters should they be good ones, even should houses, ships, and furniture be wanting.' in the years to come his experience enabled him to write his own business and commercial leaders in his paper, but as yet his income did not exceed one hundred pounds, and he willingly joined in the continuation of wilson's _tales of the borders_. this work has retained its popularity, though probably few are aware of the complexity of the authorship. as edited by leighton, it preserves the names of several writers who occupy a more or less humble niche among the minor singers of scotland, and in the list of contributors, along with miller, to the work are found the two bethunes, alexander and john. he wrote for the _tales_ a good deal of rather poorly remunerated work, and his papers on burns and fergusson afford a not unpleasing attempt to weave the lives of the two poets into an imaginative narrative. on their appearance, the papers were quoted as original reminiscences, though a more discriminating criticism could not have failed to detect their real nature. miller possessed the logical and personal element too strong to merge his own individuality successfully in the characters of others. the dramatic faculty was deficient. yet it was not quite an unfortunate attempt to thus anticipate such a sketch as dr. hutchison stirling has so admirably worked out in his _burns in drama_. into a very different arena he was now to be drawn. politically and ecclesiastically, it was a period of excitement. in catholic emancipation had no sooner been passed than o'connell brought in his motions for the repeal and the tithe war. the latter was a protest by the romanists against paying tithes for the maintenance of the irish church, whose incumbents were a mere outpost of the tory and episcopalian party, converting, as lord rosebery has said, nobody, and alienating everybody. on the withdrawal of grey, and the fall of peel, lord melbourne had carried on for years a sort of guerilla warfare with a varying majority, too dependent on the irish vote to give general satisfaction. the tithe act, however, was passed, and this made the support of the english clergy in ireland a charge upon rent. the position in which matters then stood with the government will be clearly seen by a reference to the admirable speech of macaulay, in may , to the electors of edinburgh. in ross-shire, the tension of affairs had been rendered more acute by a wave of tory reaction which induced the church of scotland to cast the weight of her influence against the whigs; but the people, as has ever been the case upon such aberrations from the national policy, had steadily declined to follow this lead, although the endowment scheme for new chapels had been dealt with by the whigs in a niggard and unsatisfactory way. in cromarty the cause of the church was strong. since the revolution, the succession in the parish had been at once popular and able. the position taken up hitherto by miller and his uncles had been a middle one. with strong hereditary attachment to the national establishment they united personal leanings which led them to a sympathy with the standpoint and the theology of the seceders. but as yet miller was, he says, 'thoroughly an established man.' the revenues of the church he regarded as the patrimony of the people; and he looked not unnaturally to a time 'when that unwarrantable appropriation of them, through which the aristocracy had sought to extend its influence, but which had served only greatly to reduce its power in the country, would come to an end.' still he confesses that as yet there were no signs of what he would himself have desired to see--a general and popular agitation against patronage--though he noted with approval the 'revival of the old spirit in the church.' the time had, however, come when he could hesitate no longer. he saw with anxiety the decisions go against the church in march , and of the lords in may , the victory of his case by the presentee to auchterarder, and the declaration of the illegality of the veto act of . 'now,' he says, 'i felt more deeply; and for at least one night--after reading the speech of lord brougham and the decision of the house of lords in the auchterarder case--i slept none.' could he not, he reasoned with himself, do something in the hour of danger to rescue the patrimony of his country out of the hands of an alien aristocracy, which since had obstinately set itself in hereditary opposition to the people? in the morning he wrote a letter addressed to lord brougham, the grandson of the historian robertson, to which we shall have occasion later on to refer in detail. this admirable piece of reasoning and clever statement--the result of a week's work--was sent to robert paul, the manager of the commercial bank in edinburgh. by him its value was quickly seen, and by the strenuous advice of dr. candlish it was at once put in print. four editions in the course of well-nigh as many weeks proved its excellence; and it was fortunate enough to secure encomiums from two men so different in their leanings as daniel o'connell and mr. gladstone. the writer who could at such a critical position produce a pamphlet of this nature was, of course, a marked man. the leaders of the evangelical party of the church in edinburgh had been engaged in a scheme for the starting of a paper. from the press of the capital, and from such provincial organs as _the aberdeen herald_ and _the constitutional_, as edited by mr. adam and mr. joseph robertson, the 'travelled thane athenian aberdeen' who drifted into the crimean war later on, and who drifted with the parliament house party in a reactionary ecclesiastical policy at this time, had been content to draw such scanty information as he ever possessed on the real issues at stake in the church of scotland. indeed, his lordship had gone so far as to taunt the evangelical party as composed but of the intellectual _débris_ of the country, and of the 'wild men' in the church. sir robert peel, who really knew nothing of the intricacies of the question, was content to believe that there was a conspiracy to defeat the law and to rend the constitution. but the ignorance of the premier and the taunt of lord aberdeen came but with an ill grace from them when flung against such men as sir david brewster, chalmers, welsh, guthrie, bonar, duff, and miller, and the whole intellectual force of the country at large. indeed, to the very last, the indecision and the ignorance as to the state of the country shown by lord aberdeen were but the natural results of his holding his ecclesiastical conscience in fee from such men as robertson of ellon, paull of tullynessle, and pirie of dyce--these bucolic personages, 'like full-blown peony-roses glistening after a shower,' whose triple and conjunct capacity, joined to that of their master, might have been cut, to borrow the eulogy of sir james mackintosh upon burke, out of the humblest of their rivals and never have been missed. it was really high time that something should be done, when lord medwyn could pose as an ecclesiastical scholar by a few garbled quotations from beza, professing to set in their true light the views held by the reformers upon patronage; and when these very extracts, together with the copious errors of the press, had been worked up by robertson of ellon to be quoted by lord aberdeen third-hand as an embodiment of oracular learning and wisdom! no apology, therefore, need here be made for the inclusion of an extract from that remarkable work by dr. william alexander--_johnny gibb_--to which we have before had occasion to refer, and which must ever rank as the classic of the movement with which miller's own name is associated. it deals with the sort of windy pabulum then served up by the aberdeen papers to obscure the real issues, and it describes in the raciest and most mellow style of the lamented writer the meeting in the schoolhouse of jonathan tawse, at whose hospitable board are assembled the three farmers and the local doctor. readers in the north of scotland can from their own knowledge read much between the lines; and they will not forget that mr. adam and mr. joseph robertson were the only two men who could be found with effrontery sufficient to shake hands with mr. edwards in the all-too notorious induction at marnoch. 'jonathan took up an aberdeen newspaper, wherein were recorded certain of the proceedings of the evangelical ministers, who were visiting different parishes for the purpose of holding meetings. first he put on his "specs," and next he selected and read out several paragraphs, with such headings as "the schismatics in a----," "the fire-raisers in b----," and so on, winding up this part with the concluding words of one paragraph, which were these:--"so ended this compound of vain, false, and seditious statements on the position of the church, and which must have been most offensive to every friend of truth, peace, or loyalty who heard it." "i say amen to ilka word o' that," said dr. drogemweal. "sneevlin' hypocrites. that's your non-intrusion meetin's. it concerns every loyal subject to see them pitten doon." '"here's fat the editor says, in a weel-reason't, and vera calm an' temperate article," continued jonathan--"he's speakin' o' the fire-raisers": "how much reliance could be placed on the kind of information communicated by these reverend gentlemen will be readily imagined by such of our readers as have read or listened to any of the harangues which the schismatics are so liberally dealing forth. if simple laymen, in pursuing objects of interest or of ambition, were to be guilty of half the misrepresentations of facts and concealment of the truth which are now, it would seem, thought not unbecoming on the part of _evangelical_ ministers, they would be justly scouted from society." "that's fat i ca' sen'in the airrow straucht to the mark."' "seerly," interposed mains, who had been listening with much gravity. "a weel-feather't shaft, tae," said dr. drogemweal. '"an' it's perfectly true, ilka word o't. they're nae better o' the ae han' nor incendiaries, wan'erin' here an' there to raise strife amo' peaceable fowk; and syne their harangues--a clean perversion o' the constitutional law, an' veelint abuse o' the institutions o' the countra."' how many specimens of that style of 'calm and temperate article' were produced in the north, no one with a recollection for either history or for humour need recall at this hour. somewhat later, miller could say in _the witness_ that in a few days he had clipped out of the papers what he had seen written against such a man of position and courtesy as mr. makgill crichton of rankeilour in the course of a fortnight. it amounted to eleven feet six inches when pieced together, and was for the most part gross abuse and vulgar personalities. the hour, then, had come and the man. miller was invited to edinburgh to meet the leaders of the evangelical party, and he was offered the position of editor of the newspaper, which started its first issue on january , , appearing bi-weekly upon wednesdays and saturdays. at the end of the bank's financial year, he was presented by his fellow-townsmen with a breakfast service of plate, and the presence of his uncle alexander was to miller a circumstance of peculiar satisfaction. in a few days later he was seated at the editorial desk. for sixteen years he was with undiminished success to edit _the witness_. but here we pause. the conflict in which he was to engage calls for a special chapter. the question has been approached from all sides, civil as well as ecclesiastical. but it is fitting that here, at least, an attempt be made to connect the struggle with the history and the peculiar mental and moral characteristics of the scottish people. it will be seen that the question involves far-reaching, deep-rooted, and closely connected points of issue. it will therefore be the attempt of the next chapter to show the really national and democratic features of the conflict, and to briefly indicate how the civil and religious rights of the people, long before staked and won by the early reformers, were again, when surrendered by an alien nobility, saved for them--from the point, at least, of abiding literature--by two men; who, sprung themselves from the people, the one the son of a cromarty sailor and the other of an aberdeenshire crofter, wrote the leaders in _the witness_ and _johnny gibb of gushetneuk_. the best years of miller's own life, sixteen years of unceasing turmoil and overwork, were spent in making these issues abundantly clear to the people. no apology need then be made for an effort to reset these positions in their historical connection, and to exhibit the logical nexus of affairs from to . chapter iii the scottish church, - --'the witness' 'the fate of a nation was riding that night.' _paul revere's ride_, longfellow. when andrew melville said to king james vi., 'sir, as divers times before have i told you, so now again must i tell you, there are two kings and two kingdoms in scotland; there is king james, the head of the commonwealth, and there is christ jesus, the king of the church, whose subject james the sixth is, and of whose kingdom he is not a king, nor a lord, nor a head, but a member,' he expressed what, from its foundation as an establishment in till now, has been in every one of its constituent parts the belief and practice of the indomitable kirk of scotland. these were words which the british solomon was to remember. over the border, where the obedient english clergy, who looked from the humblest curate to the highest dignitary to the throne alone for their support, professed to find in the pedantic pupil of the great buchanan the wisdom of a present deity and regarded his slobbering utterances as 'the counsels of a god,' james found himself in more congenial society for the promulgation of his views on kingcraft which were to embroil the nation and drive his descendants from the throne. the preface to the authorised version of the bible by the translators of shews the depth to which the anglican clergy could sink. no wonder that james found such men ready tools to his hand. in their company he could complacently vapour about 'no bishop, no king,' or express his joy in finding himself for the first time in the company of 'holy and learned men.' when melville, as professor of divinity at sedan, was dying an exile in james was dismissing the two english houses of parliament for what he was pleased to call an invasion of his prerogative; the rumours of the spanish marriage were in the air, the first instalment of the royal legacy of kingcraft. 'no bishop, no king': the nation was to take him at his word, and to demonstrate pretty effectively that kingdoms can do without either--and both. 'not a king--but a member;' 'in all matters ecclesiastical as well as civil head supreme'--the whole history of scotland was to run for three hundred years in these grooves. this is the doctrine which, from till now, has in scotland been known as the headship of christ. without a correct understanding of this question, not as a mere metaphysical or theological figment, but as a reality most vitally 'within practical politics' carrying effects direct and visible into every corner of the national life, the history of scotland must of necessity be a sealed book--the play of _hamlet_ without the royal dane. to the english reader this has been largely obscured, from the fact that the chief sources of information open to him are not such as present a rational or connected story. george borrow found that scott's caricature of _old mortality_ was what englishmen had in their minds, and that some thin romanticism about prince charles edward was the end and substance of their knowledge. yet such a presentation would be no less absurd than _hudibras_ would be for the men of the long parliament. scott was too much occupied with the external and material conditions of the country, too much engrossed by obvious necessity of materials in the romantic element of scottish history, and too little in sympathy with the spiritual and moral forces at work to present anything like a complete narrative, while his feudal sentiments were nourished by the almost entire lack of the political instinct. the ecclesiastical chapters in john hill burton's _history_ are not equal to the main body of his work; and, if the _lectures_ of dean stanley are the characteristically thin production of one confessing to but a superficial knowledge of the vast literature of the field,' the _ecclesiastical history_ of grub is only the work of a mere episcopalian antiquary, and the lack of judgment and political insight appears on every page. 'it seems to me,' says carlyle, 'hard measure that this scottish man knox, now after three hundred years, should have to plead like a culprit before the world, intrinsically for having been, in such way as was then possible to be, the bravest of all scotchmen'--harder still, say we, that the subject of milton's great eulogy should be judged by minds of the notes-and-queries order, or by those of the class of hume and robertson, who have such a gentlemanly horror at everything that savours of enthusiasm as to miss the central point, the _coincidence_ of civil and religious liberty. 'in every sense a man's religion is the chief fact with regard to him. a man's, or a nation of men's.' yet we find hume writing to robertson that if the divine were willing to give up his mary, the philosopher was willing to give up his charles, and there would at least be the joint pleasure of seeing john knox made completely ridiculous. 'who,' writes robertson to gibbon, 'is mr. hayley? his whiggism is so bigoted, and his christianity so fierce, that he almost disgusts one with _two very good things_!' christianity was then only a good thing when it had good things to offer to pluralists of the warburtonian order. yet these two garbled and distorted narratives are still the most widely known versions in england. little wonder, therefore, is it that carlyle should ask, 'i would fain know the history of scotland; who can tell it me? robertson, say innumerable voices; robertson, against the world. i open robertson; and find there, through long ages too confused for narrative, a cunning answer and hypothesis--a scandalous chronicle (as for some journal of fashion) of two persons: mary stuart, a beauty, but over light-headed; and henry darnley, a booby who had fine legs. thus is history written.' in england, the reformation took place in a way quite different from that in which it was effected in scotland. the strong hand of henry viii. piloted the nation for a time through a crisis, and for a space at least it would appear that the nation was content to surrender its religious conscience into the hands of the king. he attempted, says macaulay with perfect truth, to constitute an anglican church differing from the roman catholic on the point of the supremacy, and on that alone. there can be little doubt that to the court of henry the king was the head of both church and state, and that the power of the keys temporal as well as ecclesiastical resided in the crown. so far did cranmer carry out this idea that, regarding his own spiritual functions as having ceased with the death of henry, he renewed his commission under edward vi., and for mere denial of the act of supremacy more and fisher were sent to the block. it is true that elizabeth was induced to part with a good deal of this exaggerated prerogative, yet she still exercised such a domineering and inquisitorial power as threatened to unfrock any refractory creature of her creation. it was natural, therefore, that the church created almost exclusively by the will of the crown should for her rights and privileges rest entirely upon the crown. the people had never been consulted in her creation, and it was to the crown alone that the clergy could look. her constitution, her traditions, and her government were all monarchical; and if, at first, she was moderate in her tone of adulation, it was easy to see that, led largely by interest, she would begin to assert the divine origin of the powers of the king, with the deduction of 'no bishop, no king' and of passive obedience, which made itself heard from the pulpits of laud, montagu, and mainwaring, and in the treatise of filmer. passing from the more servile ranks of the clergy to those of the laity it appeared as the party cry of a class. to many it has often appeared strange how such an absurd and illogical doctrine could become even the shibboleth of a political party. yet at bottom the doctrine of the divine right of the king was not very unfavourable to the divine right of squires, and king and cavaliers were bound together by obvious ties of interest in the maintenance of the royal prerogative against the rising tide of political opposition. holy alliances in recent times have not found this doctrine strange to them, and a high elevation of the prerogative and the mitre was the very breath of existence to a church whose being depended on the stability of the throne. passive obedience was a convenient cry for those who never dreamed that the breath of the king could unmake them as a breath had made. never till james vii. began to oppress the clergy did they begin to see what was logically involved in their abject protestations of loyalty, and in their professions of turning the right cheek to the royal smiter. only when the seven bishops were sent to the tower, not for any loyalty to the country or to the constitution, but through a selfish maintenance of their own interests as a class, did the anglican body bethink themselves of resistance, and of texts that reminded them of the hammer of jael and the dagger of ehud no less than of the balm of the anointed of the lord. history has repeated itself. the landed and clerical classes associated their triumph with the triumph of episcopacy, and their humiliation with the triumph of the independents. the exaltation of the prerogative, therefore, again made its appearance at the restoration, to be shaken by the high-handed measures of james, and pass to extinction at the revolution. the same thing has practically been seen in spain. spain, remarks borrow, is not naturally a fanatical country. it was by humouring her pride only that she was induced to launch the armada and waste her treasures in the wars of the low countries. but to the spaniard, catholicism was the mark of his own ascendency; it was the typification of his elevation over the moor. the most catholic king was therefore flattered to exalt the claims of the holy see no less than the english clergy had exalted the prerogative of the king. far different the condition of affairs in scotland. when knox landed at leith, in may , he found the whole people ripe for a change, so that by august of next year the scottish parliament could pass a resolution to abolish the papacy with the entire consent of the nation, and in december the first general assembly met. its laic element was strong and was emphasised from the beginning. to six ministers there were thirty-four elders, and it met by no sanction of the crown, but by its own authority. at its second meeting, maitland of lethington could craftily raise the question as to the legality of such conventions without the consent of the queen. it was retorted that, if they were dependent merely upon the queen for their liberty of meeting, they would be deprived of the public preaching of the gospel. 'take from us,' said knox, 'the freedom of assemblies, and take from us the gospel'; but it was left to her to send a commissioner. so early was the doctrine of the headship maintained by the church of scotland. in , no less than , the question was clear. in they had resolved that the election of ministers, according to the custom of the primitive church, should be made by the people; and in the first book of discipline of , re-enacted in , it was laid down that 'it appertaineth to the people and to every several congregation to elect their minister, and it is altogether to be avoided that any man be violently intruded or thrust in upon any congregation.' the fabric was laid: three hundred years have not started a plank. the difference of the reformation in england and in scotland at once emerges. knox had the nation at his back; and, besides being, as milton said, 'the reformer of a nation,' he had found the people by mental temperament, or by concurrent historical reasons, anchored to a doctrinal system with a political side which has coloured ever since the stream of its existence. calvinism, in every one of its forms, exaggerated or diluted, has this double side. it is felt in this way. to a nation believing that the divine decree of election has singled out the individual, the claims of a church with the greatest of histories and the most unbroken of descents are of slight value. to the individual believing it is god's own immutable decree that has made his calling and election sure, the whole retinue of priests and priestly paraphernalia appears but an idle pageant. to the nation, and to the individual alike, regarding itself or himself as fellow-workers with god in the furtherance of his immutable decrees, thrones, dominions, principalities and powers have for ever lost their awe or a power to coerce. wherever the belief has been carried these results have been seen. there has been, what buckle failed completely to see, a rooted aversion to ecclesiasticism, and a no less rooted aversion to tyranny. and in no better words could the doctrinal and political principles be laid down than in the famous words of andrew melville which we have set at the head of this chapter. again, when knox laid hold of the nation his schemes in their very first draft embraced the people as a whole. it was not a merely piecemeal or monarchical business as in england. the reformers were not content with merely formulating an act like henry; they proceeded to carry out in detail their plans for a national system of education. they had no idea of setting up a church of their own invention. there is something in the scottish intellect, in this resembling the french, that seeks for the completest realisation in detail of its ideas. as professor masson has said, its dominant note is really not caution, with which it is so frequently credited, but _emphasis_. while the english independents during the later years of the civil war appear as either sectaries or as individualists, the contention of the scots was ever for a national system. this feature in the character of the nation is really at the root of what hallam calls the 'presbyterian hildebrandism' of the elder m'crie. johnson, too, could with some considerable truth say to boswell, 'you are the only instance of a scotchman that i have known who did not at every other sentence bring in some other scotchman.' but this is the very feature that buckle has overlooked, and it is this that explains how the new church spoke in the authoritative tones of the old; this, too, which explains how, outside of the waning episcopalian sect, there are no dissenters in scotland in the true sense. we have parties, not sects. while the secession, the relief, the cameronians, the burghers were all mere branches of the parent stock, retaining in detail its fundamental nature in discipline and worship, the established church in england finds itself face to face with organised and hostile dissent. so entirely has the national unity been preserved in scotland that professor blackie has said, with no less truth than pith, that while presbyterianism is the national and the rational dress of the land, episcopacy is but the dress coat by which the nakedness is hid of the renegade from the nation, and the apostate from its church. dean stanley found that 'the questionable idols' of the episcopalian sect were mary queen of scots, montrose, and dundee. these have never been the idols of the scottish people: the last, indeed, occupies in its memory the peculiar niche of infamy. the political side of the national religion is expressed no less clearly in facts. the scottish crown is held by a contract,[ ] and the coronation oath is the deliberate expression of it. in his _de jure regni_ in , dedicated to the king, buchanan had made this apparent to europe, and in his _lex rex_, in , buchanan was reinforced by rutherfurd in the doctrine that the people is the source of power, and his officers are merely _ministri regni non regis_, 'servants of the kingdom, not of the king.' startling doctrine this to the slobbering vicegerent of god, conceding to the people acts to be revoked at his pleasure. in the light of ordinary facts, therefore, what are the national covenants of and , but very simple magna chartas or reform bills with a religious colouring? one half of the statements of hume and robertson about fanaticism, austerity, gloom, enthusiasm, democracy, and popular ferocity, and all the bugbears of the writers so terribly 'at ease in zion,' would be discounted by a simple regard for facts. when leighton and burnet went into the west in to try and induce the people to recognise the establishment of charles, what did they find? wranglings or harangues after the manner of scott's habbakuk mucklewrath? 'the poor of the country,' says burnet, 'came generally to hear us. we were amazed to see a poor commonalty so capable to argue upon points of government, and on _the bounds to be set to the power of the civil magistrate_ and princes in matters of religion: upon all these topics they had texts of scripture at hand, and were ready with their answers to everything that was said to them. this measure of knowledge was spread even among the meanest of them, their cottagers and servants.' leighton might well have remembered the case of his own father. history loves not the coriolani, says mommsen, and miller has well seized this incident to bring out the popular side of the national religion. to the question, in an inn at newcastle, what the scottish religion had done for the people, he could reply, 'independently altogether of religious considerations, it has done for our people what your societies for the diffusion of useful knowledge and all your penny and saturday magazines will never do for yours; it has awakened their intellects and taught them to think.' [ ] for this important point in its bearing upon the position of the cameronians, and the 'testimony' of richard cameron at the market-place of sanquhar, june , , see buchanan's _history_, xx. - , and milton's _tenure of kings and magistrates_, with the coins of james vi. stamped in . thus, while james vii.'s creatures, the bishops, maintained the 'divine right' of their creator, led by paterson, the archbishop of glasgow, dalrymple could carry the resolution on the constitutional question of tenure that the king had 'forfaulted the throne.' but the exigencies of the romance-writer are often the means of corrupting history, and the largest class of readers will ever prefer to read it, in the phrase of macaulay, with their feet on the fender. to that class, therefore, the political crisis of , one of no less magnitude than the french revolution, will ever be obscured by airy talk about religious intolerance and popular fanaticism. the history of scotland in consequence becomes either, as carlyle said, a mere hunting-ground for intriguing guises or else is left to the novelist with the mucklewraths, wild men, and caricatures. even yet the mere english reader of hume and robertson has not got beyond the phrases of 'iron reformers' and 'beautiful queens.' the intrepidity of knox, like the conduct of luther at the diet, becomes material for the sentimentalist to decry or the latitudinarian to bewail. the courtly dean stanley approaches the maudlin in his remarks at this stage, and he thinks of scott as he 'murmured the lay of prince charlie on the hills of pausilippo, and stood rapt in silent devotion before the tomb of the stuarts in st. peter.' but the admirers of the greatest of all novelists will remember also no less his statement that he gave the heart without giving the head, and will even regard it as a merely temporary aberration, like his presence at carlton house with the prince regent, where, says lockhart with curious lack of humour, 'that nothing might be wanting, the prince sang several capital songs!' the spell of sir walter should not blind us to the real and the false in the national story. eminently clear-headed and politically sound were the men of , worthy compeers of the great men that sat in england's long parliament. the jacobite rebellions are a mere extraneous incident in the history of scotland, and the events of , , and will show the peculiar spirit of the people in a fairer flowering. how curiously illusory are the generalisations of philosophers! calculation, shrewdness, pawkiness--these are the traditional marks of the stage-scotchman from the days of smollett. but buchanan's _perfervidum ingenium_ is surely much truer, and mere calculation is just what is _not_ the national mark. if her poverty and pride were seen in darien, no less truly was her religious and political side seen in these other events. but the question of the headship still awaits us. on the accession of william, the shattered remnants of the kirk were gathered together by carstares after twenty-eight years of persecution: _nec tamen consumebatur_. perhaps, in the circumstances under which both king and country found themselves, no other compromise could so well have been come to as that of . the election was left in the hands of elders and the heritors, to be approved of by the people, leaving an appeal to the presbytery. at the union, scotland seeing the danger to which she was exposed by her scanty band of forty-five members being swamped in the english or tory phalanx--a danger to which every year subsequent has added but too evident a commentary--had exacted the most strenuous obligations for the unalterable preservation of her ecclesiastical system. but five years witnessed the most shameless breach of public faith, by an act which had the most ruinous effects, political and religious, upon the people. the tories had come into power on the crest of the sacheverel wave, and in bolingbroke proceeded to carry out his scheme of altering the succession and securing the return of the pretender. an act of toleration was passed for the episcopalian dissenting sect in scotland, and an oath of abjuration sought to be imposed upon the scottish church for the sake of exciting confusion. an act restoring patronage was rushed through the house by the tory squires, who composed five-sixths of the house of commons. against this the whigs and carstares protested vigorously, and appealed to the treaty of union, but appeal was lost upon the ignorant class, who were not overdrawn in the squire western of fielding's novel. for a hundred years this act bore evil fruits. the nobility of the land were only too ready to seize upon the poor spoils of the national endowment in order to renew their waning power in the country, and in so doing they managed to set themselves and their descendants in hereditary opposition to the great mass of the people. the english peerage has done much for the english people. in scotland, it may be asked, which of the four scottish universities has had a farthing of the money of the nobility, and what have they done for the church in any one of her branches? in miller's _letter to brougham_ this cardinal point of is made clear:-- 'bolingbroke engaged in his deep-laid conspiracy against the protestant succession and our popular liberties; and again the law of patronage was established. but why established? smollett would have told your lordship of the peculiarly sinister spirit which animated the last parliament of anne; of feelings adverse to the cause of freedom which prevailed among the people when it was chosen; and that the act which re-established patronage was but one of a series, all bearing on an object which the honest scotch member who signified his willingness to acquiesce in one of those, on condition that it should be described by its right name--an act for the encouragement of immorality and jacobitism in scotland--seems to have discovered. burnet is more decided. instead of triumphing on the occasion, he solemnly assures us that the thing was done merely "to spite the presbyterians, who, from the beginning, had set it up as a principle that parishes had, from warrants in scripture, a right to choose their ministers," and "who saw, with great alarm, the success of a motion _made on design_ to weaken and undermine their establishment"; and the good sir walter, notwithstanding all his tory prejudices, is quite as candid. the law which re-established patronage in scotland--which has rendered christianity inefficient in well-nigh half her parishes, which has separated some of her better clergymen from her church, and many of her better people from her clergymen, the law through which robertson ruled in the general assembly, and which brougham has eulogised in the house of lords, that identical law formed, in its first enactment, no unessential portion of a deep and dangerous conspiracy against the liberties of our country.' the immediate result was seen in the conduct of the patrons. as the regent morton had established tulchan bishops and secured the revenues of the sees, the patrons now named such presentees as they deliberately saw would be unacceptable to the people, protected as they were by the appeal to the presbytery, so that during the protracted vacancy they drew the stipend. no actual case of intrusion, however, seems to have occurred until , but the rise of moderatism[ ] within the church gave too frequent occasion for such forced presentations as, we have seen, took place at nigg, in , in the days of donald roy, miller's relative. the secessions of the erskines in and of the relief under gillespie in were the results of intolerant moderatism, and its long reign under robertson the historian, lasted for well-nigh thirty years in the assembly, till his withdrawal in . [ ] for the similar rise of the spirit in england see mark pattison's excellent paper in _essays and reviews_, 'tendencies of religious thought in england, - . were we to credit the eulogies of dean stanley and others upon home, blair, and robertson, we should regard this as the golden age of the church of scotland. robertson he describes as 'the true archbishop of scotland.' but there are men who seem fated, in the pregnant phrase of tacitus, to make a solitude and call it peace. the reign of robertson was simply coincident with the very lowest spiritual ebb in the country, to which his own long régime had in no slight degree contributed. the spaniard dates the decline and fall of his own country from the days of philip ii., _segundo sin segundo_, as cervantes bitterly calls him, 'the second with (it was to be hoped) no successor.' even in , such had been the spread of religion outside the national establishment that the assembly was forced to reckon with it. they found 'a hundred and twenty meetinghouses, to which more than a hundred thousand persons resorted.' patronage was found, after debate, to be the cause. it is no tribute to alva that he found the low countries a peaceful dependency of spain and left them a free nation; none to the policy of 'thorough' that it sent laud and strafford to the block. an impartial verdict will be that robertson undermined for ever the edifice which carstares had reared. an attempt has been recently made again to cast a glamour over the old scottish moderates of the eighteenth century. their admirers point to watson the historian of philip ii., to henry the historian of britain, to robertson, to thomas reid the philosopher, home the dramatist, blair the sermon-writer, adam ferguson, hill of st. andrews, and george campbell of aberdeen. not even the paraphrases have escaped being pressed into the field to witness to the literary and other gifts of oglivie, cameron, morrison, and logan. but the merits of a class are not best seen by the obtrusion of its more eminent members, but by the average. we do not judge the provincial governors of rome by such men as the occasional cicero and rutilius, but by the too frequent repetition of men like verres and piso. nor even in these very upper reaches will the moderates bear a close inspection. no one now reads home's _douglas_. young norval has gone the way, as the critic says, of all waxworks, and curious is the fate of the great blair: he lives not for the works upon which immortality was fondly staked, but for having given breakfasts to burns in his edinburgh days. 'i have read them,' says johnson of these sermons; 'they are _sermones aurei ac auro magis aurei_. i had the honour of first finding and first praising his excellencies. i did not stay to add my voice to that of the public. i love blair's sermons, though the dog is a scotchman and a presbyterian, and everything he should not be.' this avalanche of laudation seems strange to the modern reader, who will find in them the rhetoric of hervey's _meditations on the tombs_, united to a theology that could pass muster in a deistical writer. burns, though he lent himself to be the squib-writer of the ayrshire moderates, was fully aware of the merely negative tenets of the school, and in his _holy fair_ he asks 'what signifies his barren shine of moral powers and reason? his english style, and gestures fine are a' clean out o' season. like socrates or antonine, or some old pagan heathen, the moral man he does define, but ne'er a word of faith in, that's right this day.' but the spirit of moderatism was to be fully seen in the debate upon missions in . it was moved in the general assembly by robert heron, the unfortunate friend of burns, and deeply shocked was old jupiter carlyle. it wounded the feelings for the proprieties of the old man. for half a century, said he, had he sat as a member, and he was happy to think that never till now had he heard such revolutionary principles avowed on the floor of the house! clergymen of lax life, and whose neglect of parochial duties was notorious, were unanimous in declaring that charity should begin at home. the spectre of tom paine rose before them. never, they maintained, while still there remained at home one man under the influence of attack from the _age of reason_, should such a visionary overture be entertained. but there was worse behind this. the missionary societies were united with various corresponding centres; accordingly, in the days of the dundas dynasty, when burns during this very year was reminded that it was his place to act and not to think, when the alien and traitorous correspondence act of and the suspension of the habeas corpus act in had revived the worst of obsolete and feudal enactments, a wily use of this reign of terror was made to defeat missions by an attack on their supposed insidious and political designs. the lawyer who was afterwards to sit on the bench as lord president boyle, rose and said: 'the people meet under the pretext of spreading christianity among the heathen. observe, sir, they are affiliated, they have a common object, they correspond with each other, they look for assistance from foreign countries, in the very language of many of the seditious societies. already, it is to be marked, they have a common fund. where is the security that the money of this fund will not, as the reverend principal [hill of st. andrews] said, be used for very different purposes? and as for those missionary societies, i do aver that, since it is to be apprehended that their funds may be in time, nay, certainly will be, turned against the constitution, so it is the bounden duty of this house to give the overtures recommending them our most serious disapprobation, and our immediate, most decisive opposition.' the legal mind is not often remarkable for profundity, but the fine violation of reasoning in the 'nay, certainly will be,' is just on a par with jonathan tawse's 'clean perversion of the constitutional law,' which we have seen before. the detection of treason, too, lurking in the apparently harmless missions fairly rivals serjeant buzfuz in _pickwick_, with his exposure of the danger underlying the 'chops and tomato sauce' of the defendant. such had been the unhappy legacy of robertson. such was the legal spirit infused from the bar to the bench that was to act in decisions against the true interests of the church during the ten years' conflict. but the tide was to turn. years of dissatisfaction had at last produced the inevitable reaction, and in the general assembly had bowed to the storm and passed the veto act. then were discovered the evils of co-ordinate jurisdictions, the mistake committed in and by which no provision had been made for a line of clear demarcation between the ecclesiastical and civil courts, and the blunder committed in intrusting great questions affecting scotland to the judgments of aliens in political sympathies. the tone of many a decision of the house of lords was to make people think upon seafield's brutal jest about 'the end of an auld sang,' and belhaven's trumpet-warning about the risks to the 'national church founded on a rock, secured by a claim of right, descending into a plain upon a level with jews and papists.' there were limits even to the loyalty of the most faithful, and for ten weary years the conflict between the courts was to run its course. in the church had instructed its lord high commissioner to lay before her majesty a series of resolutions by which it was hoped that a rupture could be averted. on the th of may the commissioner for the crown was the marquis of bute, and after the levée in holyrood palace, the retiring moderator, dr. welsh, preached in st. giles, and in st. andrew's church the assembly--the last assembly of the real church of scotland--met. the scene so often described had best be given in miller's own words, as at once affording a capital specimen of his editorial style and as the work of an eye-witness. we abridge from his leader of may :-- 'the morning levée had been marked by an incident of a somewhat extraordinary nature, and which history, though in these days little disposed to mark prodigies and omens, will scarce fail to record. the crowd in the chamber of presence was very great, and there was, we believe, a considerable degree of confusion and pressure in consequence. suddenly,--whether brushed by some passer by, jostled rudely aside, or merely affected by the tremor of the floor communicated to the partitioning, a large portrait of william the third, that had held its place in holyrood for nearly a century and a half, dropped heavily from the walls. "there," exclaimed a voice[ ] from the crowd,--"there goes the revolution settlement." for hours before the meeting of assembly, the galleries of st. andrew's church, with the space behind, railed off for the accommodation of office-bearers, not members, were crowded to suffocation, and a vast assemblage still continued to besiege the doors.... the moderator rose and addressed the house in a few impressive sentences. there had been infringement, he said, of the constitution of the church,--an infringement so great, that they could not constitute the assembly without a violation of the union between church and state, as now authoritatively defined and declared. he was, therefore, compelled, he added, to protest against proceeding further, and, unfolding a document which he held in his hand, he read, in a slow and emphatic manner, the protest of the church. for the first few seconds, the extreme anxiety to hear defeated its object,--the universal "hush, hush," occasioned considerably more noise than it allayed; but the momentary confusion was succeeded by the most unbroken silence; and the reader went on till the impressive close of the document, when he flung it down on the table of the house and solemnly departed. he was followed at a pace's distance by dr. chalmers; dr. gordon and dr. patrick m'farlan immediately succeeded, and then the numerous sitters on the thickly occupied benches behind filed after them, in a long unbroken line, which for several minutes together continued to thread the passage to the eastern door, till at length only a blank space remained. as the well-known faces and forms of some of the ablest and most eminent men that ever adorned the church of scotland glided along in the current, to disappear from the courts of the state institution for ever, there rose a cheer from the galleries. at length, when the last of the withdrawing party had disappeared, there ran from bench to bench a hurried, broken whispering,--"how many? how many?"--"_four hundred_": the scene that followed we deemed one of the most striking of the day. the empty vacated benches stretched away from the moderator's seat in the centre of the building, to the distant wall. there suddenly glided into the front rows a small party of men whom no one knew,--obscure, mediocre, blighted-looking men, that, contrasted with the well-known forms of our chalmers and gordons, candlishes and cunninghams, m'farlans, brewsters, and dunlops, reminded one of the thin and blasted corn ears of pharaoh's vision, and like them, too, seemed typical of a time of famine and destitution.' [ ] the 'voice' of this now famous utterance was william howieson crauford, esq. of craufurdland. 'i am proud of my country, no other country in europe could have done it,' said lord jeffrey. the church had simply, in , reverted to the precedents of and , and had, in the simile of goldsmith happily used by miller on the occasion, returned like the hare to the spot from which it flew. edinburgh, he maintained, had not seen such a day since the unrolling by johnston of warriston of the parchment in the greyfriars'. there was a secession, not from the church, but from the law courts, and temporary majorities of the assembly. but the evil men do lives in brass after them, and the act of had rent the church of scotland. no other country had been so fortunately situated for the exemplification of an unbroken and a national church. it was left to two tory governments to ruin it, but opportunities once lost may not thereafter be recovered. under the long reign of moderatism it looked as if the _nec tamen consumebatur_ were indeed to be a mockery. but the revival of national feeling at the beginning of the century, and the expression of popular rights in the reform bill of , were waves that were destined to extend from the nation to the church. the great book of m'crie in had truly been fruitful of results. for a century moderatism had reigned on a lost sense of nationality. but, as for long the history of rome had been written with a patrician bias and an uneasy remembrance of that figure of tiberius gracchus, so through the influence of m'crie the figure of john knox had again risen to popular consciousness in scotland. there they could see a greater than the boyles, the hopes, the kinnoulls, the broughams, and the aberdeens. yet, till its publication, the face of m'crie had been almost unknown upon the streets of edinburgh. and the succession? did it abide with the free church or the residuary establishment? lord macaulay will show, in his speech in the house of commons on july , , what the violation of the treaty of union had effected in , and that 'the church of boston and carstares was not the church of bryce and muir, but the church of chalmers and brewster.' no one knew that better than hugh miller, and no one had done more to make the issues plain to the people of scotland. to him it was 'the good cause,' as macaulay in his address to the edinburgh electors had styled his own. while a plank remained, or a flag flew, by that it was his wish to be found. it was the cry which m'crie had said, 'has not ceased to be heard in scotland for nearly three hundred years.' from his first leader in _the witness_, of january , , to the close of his life in , he was to send forth no other sound. 'your handwriting did my heart good,' he writes in a letter before us, of th october , to his friend patrick duff in elgin, 'and reminded me of old times long before i became ill-natured or dreamed of hurting any one. i am now "fighting in the throng"--giving and taking many a blow. but i am taking all the care i can to strike only big wicked fellows, who lift hands against the kirk, or oppress the poor man.' napoleon feared three papers more than ten thousand bayonets, and certainly miller was a tower of strength not to be found in the adverse battalions. none of the merely 'able editors' of the establishment party, much less the pamphleteers of the quality of dean of faculty hope, could touch him or find a link in his armour. this was a tribute to character. the men of the opposition had 'nothing to draw with, and the well was deep'; and many names then blown far and wide by windy rumour, such as dr. cook, robertson of ellon, dr. bryce, and principal pirie of aberdeen, survive like flies in amber only because it was their misfortune to be associated with great men. he might have said with landor that he did not strive with these men, for certainly of them all 'none was worth his strife'; yet, though individually contemptible, they formed a solid phalanx of moderatism and of dead resistance to argument and conviction. it was a time of great men. if chalmers was the incarnation of the country and the movement, murray dunlop its jurist, cunningham and candlish its debaters, it was yet to the leaders in _the witness_ that the great mass of his countrymen looked for the opinions of hugh miller. his relative, dr. gustavus aird of creich, the late moderator of the free church, has informed us that in his own parish he learned the paper was read out in the mill, and that in many places the same thing took place. it is well to have the ear of the country, and it was well at the critical hour that there was a man found who was heard gladly of the common people. chapter iv in edinburgh--last years 'in close fights a champion grim, in camps a leader sage.' scott. 'we have had,' says dr. guthrie in a letter dated th september , 'a meeting about our newspaper. miller, i may say, is engaged, and will be here, i expect, in the course of two or three weeks. his salary is to begin with £ , and mount with the profits of the paper. i think this too little, but i have no doubt to see it double that sum in a year or two--johnstone to be the publisher, we advancing £ , and he will need other two. i am down with brown, candlish, and cunningham for £ each. a few individuals only have as yet been applied to, and already £ of the £ has been subscribed.' his household he left behind him in cromarty for the time, and he lodged in st. patrick square. fortunate was it for the people that at the right time its ear should have been caught by such a writer, one whose voice in the arena was at once recognised by the individuality of its tone. the edinburgh press had long been held by the moderate party, and the belief had been that the conflict was a mere clerical striving for power. it remained for miller to educate the party, and to such effect was this done that, while the non-intrusion petition to parliament in from edinburgh had borne but five thousand signatures, the number, says robert chambers, mounted in the first year of _the witness_ to thirteen thousand. it was clear to all scotland that there was a new richmond in the field. it is the more necessary to insist on this, because the clerical mind, which after malebranche is too prone to see everything in itself and its own surroundings, has never fully confessed the services to the country of the layman. as guthrie points out, a silence is maintained all through buchanan's _ten years' conflict_ on miller. this he regrets, not only on the ground that it would be hamlet without the prince of denmark, but also for its missing the cardinal principle that at such a time the press and public meetings form the most influential of factors. this such a kindred spirit and public orator as guthrie is quick to see, nor does he go beyond the facts of the case, or the judgment now of the country, in maintaining that 'miller did more than any dozen ecclesiastical leaders, and that, chalmers excepted, he was the greatest of all the men of the ten years' conflict.' he certainly was no half advocate or mere 'able editor' in the carlylean phrase. if chalmers, candlish, and cunningham were the leaders in the ecclesiastical courts, murray dunlop the jurist, miller was the pen-man of the party. 'his business,' says guthrie, the orator of the movement, 'was to fight. fighting was miller's delight. on the eve of what was to prove a desperate conflict, i have seen him in a high and happy state of eagerness and excitement. he was a scientific as well as an ardent controversialist; not bringing forward, far less throwing away, his whole force on the first assault, but keeping up the interest of the controversy, and continuing to pound and crush his opponents by fresh matter in every succeeding paper. when i used to discuss questions with him, under the impression, perhaps, that he had said all he had got to say very powerful and very pertinent to the question, nothing was more common than his remarking, in nautical phrase, "oh, i have got some shot in the locker yet--ready for use, if it is needed"!' and that it was needed, in his own and the church's interest, the pamphlets of abuse by which he was attacked, and which would form a small library, would remain to show. thus he was really, all the more from his isolated position, as we shall see, indebted to what professor masson, in an appreciation of him in _macmillan's magazine_ for , describes as the goethean 'demonic element.' he had a better knowledge, he shows, of the country and its ecclesiastical history than was possessed by his clerical colleagues, and along with this went what he calls 'a tremendous element of ferocity, more of the scandinavian than the celt, leaving his enemy not only slain but battered, bruised and beaten out of shape.' this, though in a sense exaggerated, is true to the extent that he entered the lists not as a mere servant, but as a convinced defender of the liberties of the people. to touch on anything that infringed upon the presbyterian history of the country--be it by the duke of buccleuch, the duke of sutherland, or other site-refusing landlords of the day, or by some flippant alien and episcopalian pamphleteer among the briefless of the parliament house, was certainly to court a bout from which the unwary disputant emerged in a highly battered condition. yet his pugnacity was really foreign to the nature of the man. his surviving daughter informs the writer he was 'a very mild and gentle father, and his whole attitude was one depressed with humility.' it was, however, well for site-refusers and factors riding on the top of their commission from absentee landlords to feel that attacks upon their policy in _the witness_ were not to be lightened by any hopes of an apology or by appeals to fear. 'the watchman,' he writes in a letter before us, dated th october , 'is crying half-past twelve o'clock, and i have more than half a mile to walk out of town between two rows of trees on a solitary road. fine opportunity for cudgel-beating factors i carry, however, with me a five-shilling stick, strong enough to break heads of the ordinary thickness, and like quite as well to appeal to an antagonist's fears as to his mercy.' _the witness_ started with a circulation of six hundred. its position among the scottish papers was at once assured, and no greater proof of the personality of the editor and the quality of 'the leaders' remains than in the curious fact that, now after half a century, to the great mass of the people his name has been not miller, nor mr. miller, but hugh miller. as in the similar case of john bright the people seized on the fact that here was a writer and speaker sprung from themselves, and his christian name was as familiar as his surname. yet, curiously enough, from first to last he never believed in the profession of an editor, and from the 'new-journalism' of the paragraph and the leaderette he would have turned in disdain. nothing but the fact that he felt convinced of his mission would have induced him to leave cromarty for the post. 'i have been,' he could truly say, 'an honest journalist. i have never once given expression to an opinion which i did not conscientiously regard as sound, nor stated a fact which, at the time at least, i did not believe to be true.' he never mastered, or felt it necessary to master, the routine details of the business, for the paper was read not for its parliamentary reports, or the exposition of party politics, but for the essays, sketches, or leaders which were known to be by him. accordingly the mere fluent production of 'copy,' and the diurnal serving up of the editorial thunder by which the members of the fourth estate fondly delude themselves that they lead public opinion, never really came naturally to him. he prepared himself carefully for his work; and perhaps the bi-weekly issue of the paper and its peculiar nature lessened the strain upon the editor. his successor in the editorial chair of the paper, dr. peter bayne, in the preface to miller's _essays_ ( ) says: 'he meditated his articles as an author meditates his books or a poet his verses, conceiving them as wholes, working fully out their trains of thought, enriching them with far brought treasures of fact, and adorning them with finished and apposite illustration. in the quality of _completeness_ those articles stand, so far as i know, alone in the records of journalism. for rough and hurrying vigour they might be matched, or more, from the columns of the _times_; in lightness of wit and smart lucidity of statement they might be surpassed by the happiest performances of french journalists--a prévost-paradol, or a st. marc girardin; and for occasional brilliancies of imagination, and sudden gleams of piercing thought neither they nor any other newspaper articles, have, i think, been comparable with those of s. t. coleridge. but as complete journalistic essays, symmetrical in plan, finished in execution, and of sustained and splendid ability, the articles of hugh miller are unrivalled.' certainly few modern editors could produce such a leader as he did on dugald stewart (aug. , ), or upon the _encyclopoedia britannica_ (april , ), or could, finding themselves for a day in london, 'when time hung heavy on my hands,' buy a cheap reprint of eugene sue's _wandering jew_ and convert its hurried perusal into a capital paper on the conflict between continental ultramontanism and liberalism. the individuality of the writer and the tenacity with which he held to his opinions gave the journal a tone naturally impossible to an ordinary party paper. the great mass of the readers of _the witness_ were of course liberals, yet he strenuously contended against making it an organ of any political party. part of the prospectus ran--'_the witness_ will not espouse the cause of any of the political parties which now agitate and divide the country. public measures, however, will be weighed as they present themselves, in an impartial spirit, and with care proportioned to their importance.' he had noticed, he said, the church of scotland for a time converted by conservatism into a mine against the whigs, and he was determined that no 'tool-making politician' should again convert it to a party weapon. it was to remain the organ of 'the free church people against whig, tory, radical, and chartist.' so careful was he of the good name of the paper that he 'often retained communications beside him for weeks and months, until some circumstance occurred that enabled him to determine regarding their real value.' chalmers read the paper to the last with approval, and this was a source of joy and support to miller. nothing but such a wise supervision could have piloted _the witness_ through the abuse and the inventions of the tory organs. when the _edinburgh advertiser_, of june , , could try to improve on that rhetorical flight of barrère, characteristically fathered by its author on 'an ancient author,' about the tree of liberty being watered by the blood of tyrants, by an assertion that _the witness_ had 'menaced our nobles with the horrors of the french revolution, when the guillotine plied its nightly task, and the bloody hearts of aristocrats dangled in buttonholes on the streets of paris!'--proof was naturally wanting. a phantom of a 'grey discrowned head sounding hollow on the scaffold at whitehall' was also served up by that paper, in its devotion to the house of buccleuch, as a threat in which the irate scribe professed to detect a subtle attack on the house of hanover in the interests of the free church. 'i am a whig, in politics,' he said, 'never a radical or conservative.' he had no cheap sympathy with the working men, for them he had seen on their worst side. 'three-fourths of the distress of the country's mechanics (of course not reckoning that of the unhappy class who have to compete with machinery) and nine-tenths of their vagabondism will be found restricted to inferior workmen, who like hogarth's "careless apprentice," neglected the opportunity of their second term of education. the sagacious painter had a truer insight into this matter than most of our modern educationists.' he was no believer in household, much less in universal, suffrage, and as an admirer of delolme's views on our constitution, the radical he regarded as a 'political quack,' convinced as he was that 'those who think must govern those that toil.' but he advocated, along with guthrie, a system of undenominational education of a kind pretty much what is now established, a moderate extension of the franchise, abolition of entail, and the game laws. the maynooth grant and macaulay he opposed. he was an oliverian for ireland, and the cause of much trouble in the most distressful country he viewed as associated with that subsidy, which he would have preferred to see converted into a grant for science. indeed, like most of his countrymen he had a strong view of historical, as distinguished from mere party, conservatism. the last has of course been rendered simply impossible in scotland by the history and the ecclesiastical tenets of the country, but he ever carried about him something like the conviction of dr. livingstone, that the common people of scotland had read history and were no levellers. thus he held, like burke, to what mr. morley calls 'the same energetic feeling about moral laws, the same frame of counsel and prudence, the same love for the slowness of time, the same slight account held of mere intellectual knowledge.' this historic conservatism of burke would be taken by most scotchmen as a pretty good basis for reasoned liberalism, and the fixity of miller's main positions only exposed him the more to the wearisome tory vocabulary of 'high-flyer, fire-raiser, fanatic,' etc. admirably in the _letter to brougham_ does he seize on the ground of the political liberalism of scotland:-- 'i, my lord, am an integral part of the church of scotland, and of such integral parts, and of nothing else, is the body of this church composed; nor do we look to the high places of the earth when we address ourselves to its adorable head. the earl of kinnoul is not the church, nor any of the other patrons in scotland. why, then, are these men suffered to exercise, and that so exclusively, one of the church's most sacred privileges? you tell us of "existing institutions, vested rights, positive interests." do we not know that the slave-holders, who have so long and so stubbornly withstood your lordship's truly noble appeals in behalf of the african bondsman, have been employing an exactly similar language for the last fifty years; and that the onward progress of man to the high place which god has willed him to occupy has been impeded at every step by existing institutions, vested rights, positive interests?' bitter words, surely, all this for the ecclesiastical wirepullers of , and inheritors of the policy of the hopes and muirs, when in approaching the government with a statement of the intolerable strain of patronage, they tabled that same _letter to brougham_! to the last, miller clung to 'the established principle.' this need not seem wonderful. the free church he regarded as the church of scotland in all but the state tie, the more so that the coercion by the civil courts had not failed to impress him with the conviction that the headship, as stipulated for the scottish establishment by the treaty of union, though defeated by bolingbroke and lost in the stagnation of the eighteenth century, had passed as an integral part of her constitution to the free church. the difficulty attaching to his position proved an unfortunate source of tension between him and some of the leaders, and to this was due that lamentable quarrel with dr. candlish which he carried to his grave, and which perhaps broke his heart, for he was what lord cockburn had called their mutual friend murray dunlop, 'the purest of all enthusiasts' and though miller triumphed absolutely, yet it was not in human nature to forget that the attack was, however sincere, an attack upon cherished convictions. there can be, therefore, no good now in minimising the fact that dr. candlish, in his zeal to secure a political and tempting opportunity against the tory party, was led to enter on a quarrel with miller. the action really amounted to a motion of no confidence in his editorial management. he proposed to centralise the church press, and to secure the intrusion of a sub-editor on the existing staff, and the conversion of the paper into an explicit and active party organ. but by this time miller had become one of the proprietors, by undertaking to pay back by instalments the thousand pounds advanced by johnstone to the subscribers, with the interest, year by year, of the unpaid portion till the whole debt should be extinguished. the most objectionable feature was the proposal to secure the services of some smart parliament house 'able editor.' _the witness_ had been accused of 'preferring protestantism to macaulay, and damaging the elections.' in this was shown the cloven foot, for it was an attempt to run the paper for the whigs, and to render it the organ of the legal lights of the parliament house in pursuit of official posts and spoil, of which miller justly thought they had enough. besides, the fall of a government would mean the fall of that government paper, and thus its influence as the organ of free churchmen would be damaged. already the paper had parted with one of its best men who had been attracted to _the times_, and in the whole scheme miller saw 'a censorship; and the censor, assisted by the nice taste and tact of the parliament house editor, is to be dr. candlish.' but, he asks, 'who was to control dr. candlish?' he could not see the paper jockeyed for a government, and he stood aloof from 'exhalations blown aslant, over the faces of even the evangelical churches, from the bogs and fens of a hollow liberalism that professes to respect all religions, and believes none.' he felt that he had the people behind him, and 'possessing their confidence, i do not now feel justified in retiring from my post: dr. candlish and his parliament house friends are not the ministers and people of the free church of scotland--"of wiles, more inexpert, i boast not,"--the difference must either close entirely, or the people of scotland must be made fully acquainted with the grounds on which it rests.' the unfortunate rupture closed by the very pointed question by chalmers, 'which of you could direct hugh miller?' meanwhile, in the highlands and islands, things were for a time going hard with the now disestablished church. in some cases they had to preach 'where the snow was falling so heavily upon the people, that when it was over they could scarcely distinguish the congregation from the ground, except by their faces.' baird of cockburnspath had passed away in a room, 'a few inches above which were the slates of the roof, without any covering, and as white with hoar frost within as they were white with snow without. his very breath on the blankets was frozen as hard as the ice outside.' at canonbie, guthrie had passed johnny armstrong's tower, and preached in wind and rain to a large congregation, 'old men, apparently near the grave, all wet and benumbed with the keen wind and cold rain.' in cromarty, miller's old friend stewart was now preaching in the factory close, and there, in the summer of , after a night of rain had swept the streets, his mind reverts to the congregations over scotland in the open air--'i do begrudge the moderates our snug, comfortable churches. i begrudge them my father's pew. it bears date , and has been held by the family, through times of poverty and depression, a sort of memorial of better days, when we could afford getting a pew in the front gallery. but yonder it lies, empty within an empty church, a place for spiders to spin undisturbed, while all who should be occupying it take their places on stools and forms in the factory close.' the subtle mark of scottish _gentility_ in the allusion to the pew will not fail to strike the reader. let it not be said that it savours of 'gigmanity'--in that standing bugbear of carlyle! in he set out on a geological ramble round the hebrides in the floating manse, '_the betsey_,' by which the church served the islands in the west, owing to the refusal of sites by lord macdonald and others. the yacht was but thirty feet by eleven, and there with his old cromarty friend swanson, the 'outed' minister of the small isles, he learned the hardships to which the miserable policy of the landlords had exposed the poor highlanders. but if 'the earth was the _lairds'_ and the fulness thereof,' the water was not! the building in which the congregation met was of turf--'the minister encased in his ample-skirted storm-jacket of oiled canvas, and protected atop by a genuine sou'wester, of which the broad posterior rim sloped half a yard down his back; and i, closely wrapped up in my grey maud, which proved, however, a rather indifferent protection, against the penetrating powers of a hebridean drizzle.' in none of his works does he exhibit a happier descriptive view than in _the cruise of the betsey_, though in popularity it has been surpassed by his _first impressions of england_, where he records the results of an eight weeks' tour, in , from newcastle to london, passing york, birmingham, and stratford on the way. in he published his _footprints of the creator_, in reply to the _vestiges_ by robert chambers, in which he seeks to controvert the theory of development, at least in the form in which it was then presented, by attempting to prove the fishes and the fossils of the old red to be as advanced in character as those now existing. a racy sketch on _the geology of the bass_ formed part of a contribution to a work then issued, dealing with the history, botany, and zoology of the bass rock. the copyright of this he reserved with a view to its subsequent incorporation into a long-projected geological survey of scotland. but this cherished idea he never lived to accomplish, though such a work from his hand would have been well-nigh final and perfect in its descriptive graces. he was still in the enjoyment of his great physical power in spite of the severe strain to which his editorial and literary labours exposed him, added to as these were by his appearances in london and elsewhere as a public lecturer. as an exponent of science he could attract an audience in exeter hall of five thousand persons, whose attention he held to the close in spite of his northern accent; though perhaps this, like the fifeshire speech of chalmers and the annandale tongue of carlyle, may have given an extra charm to the individuality of the lecturer. the quarrel with candlish had thinned the ranks of some of his friends, nor did he ever draw to the circle of edinburgh as he had done to those in cromarty. he was not to be easily got at by the eminent men who sought his acquaintance, yet it is with pleasure we catch occasional glimpses of him in the society of the best that either edinburgh or london could produce. stewart in cromarty had passed away, in , during the prosecution to him of a call to st. george's to succeed candlish, who had been translated to the college chair left vacant by chalmers. none of his friends were nearer to him than mackgill-crichton of rankeillour in fife, and there we find him one christmas along with sir david brewster and guthrie. both miller and his host were men of great physical powers, and--as professor masson notes--the geologist had a habit of estimating men by their physique. crichton had narrated how he had started by the side of the mail coach as it passed his gates, and after a run of twenty miles he had been the first at the ferry. 'a horse could do more than either of you,' was the amused rejoinder of brewster. the issue of his _schools and schoolmasters_ ( ), republished from the columns of his paper, brought him warm encomiums from carlyle, robert chambers, and others. miller in politics and other points differed strongly from chambers, and of course at this time the secret of the authorship of the _vestiges_ had not been divulged. yet beautifully does chambers, to whom scottish publishing and periodical literature owes so much, refer to the early days in cromarty in comparison with his own struggles in peebles. readers who may have not quite forgiven some passages in chambers's _history of the rebellion of _ will doubtless soften their asperity after reading chambers's account of his struggling through a whole set of the _encyclopædia britannica_ which he had in a lumber garret,--setting out at sixteen, 'as a bookseller with only my own small collection of books as a stock--not worth more than two pounds, i believe, quickly independent of all aid--not all a gain, for i am now sensible that my spirit of self-reliance too often manifested itself in an unsocial, unamiable light, while my recollections of "honest poverty" may have made me too eager to attain and secure worldly prosperity. had i possessed uncles such as yours, i might have been much the better of it through life.' the close was cheered by the thought that he had fairly earned the admiration and confidence of his country. yet nothing that could in any way fetter his editorial independence or freedom of action could he permit. when the money invested in _the witness_ was offered to him by chalmers it was firmly declined, and the proposal to requite his services to the country by providing him with a residence he would not allow. 'i know,' he said, 'that as the defender of free church principles my intentions have been pure and loyal, but i am not quite sure i have been successful in doing the right thing, nor have i done anything that is worthy of such consideration from my friends. i believe my way is to make yet.' the same was his answer to a proposal to allow his name to stand for election as lord rector of marischal college in aberdeen; he met it pretty much in the vein of carlyle at edinburgh, when he felt that here was a generation in young scotland rising up who seemed to say that he had not altogether, after a hard-spent day, been an unprofitable servant. time had softened the ecclesiastical asperities of other years, and in lord dalhousie wrote to lord aberdeen to secure his election for the vacant chair of natural history in edinburgh. but it fell to edward forbes. again he was singled out by lord breadalbane, in , and he was offered the post of distributor of stamps for perthshire, an office which would to him have been a comfortable sinecure, securing alike competence and much leisure. for twenty-eight years wordsworth in westmoreland filled such a post, and miller's banking experiences would have fitted him perfectly for it. but he felt that a man turned fifty could not take up a new vocation with success. that in this he was too modest there can be no doubt; but after a brief consideration he made up his mind to decline. 'i find,' he said, 'my memory not now so good as it was formerly. i forget things which i was wont to remember with ease. i am not clear, in such circumstances, about taking upon me any money responsibility.' in fact, the long and severe strain of sixteen years had told. of the extraordinary memory whose failure he regrets, guthrie supplies a forcible example. in the shop of johnstone the publisher a discussion turned on some debate in the town council, when miller said it reminded him of a scene in galt's _provost_. he repeated the passage, halting at the speech of the convener of the trades, but was evidently vexed at the temporary breakdown. he got a copy from the front shop, and turned up the passage. then they learned that, though it was fifteen years since last he had seen the book, he had repeated page after page _verbatim_. the year was one remarkable for garotte robberies. this awakened in the overtaxed brain of miller a fear for his museum of geological specimens which he had housed for himself at shrub mount, portobello. the last four years of his life he had spent there, and often he would leave the house and return late in the evening after hours of investigation of the coast line and geological features of leith and the surrounding country. he knew his edinburgh thoroughly; some of his happiest papers are to be read in his _edinburgh and its neighbourhood_; and it was after one of these excursions that sir archibald geikie had seen him, as he describes in the reminiscence to be found in the last pages of this work. the fear of burglars had taken hold firmly of his imagination, and he resumed the habit of bearing fire-arms which he had begun at cromarty when carrying the money of the bank between that town and tain. the inflammation of the lungs in his early days as a mason had again at intervals returned, and his sleep was broken by dreams of such a harassing nature that he would wake in the morning to examine his clothes, in the belief that he was now the victim of evil spirits. in such a condition it was not unnatural that his mind should take a colour from other days, where the reader may remember his own account of seeing the figure at the door after his father's death. professor masson, we see, notes this point, and he believes that miller felt a strange fascination for all stories of second-sight. though he never wrote or spoke of such, except in the sober tone of science, yet 'my impression,' he says, 'is that hugh miller did all his life carry about him, as scott did, but to a greater extent, a belief in ghostly agencies of the air, earth, and water, always operating, and sometimes revealing themselves. one sees his imagination clinging to what his reason would fain reject.' the only hope lay in a total cessation from all work, but this was found impossible through the almost second nature which over-exertion had become to him. he had also a rooted dislike for all medicines, and it was with difficulty that he was induced to put himself under the management of dr. balfour and professor miller. the last day of his life was given to the revision of the proof-sheets of his _testimony of the rocks_, and in the evening he turned over the pages of cowper, whose works had ever been among his standard favourites. by a curious fatality his eye rested on _the castaway_, written by the poet in a similar mental condition, and which for sustained force and limpid expression is unrivalled as a religious lyric. he retired to rest on the night of the th december . next morning, his body, half-dressed, was found with a bullet from a revolver through his left lung. he had lifted a heavy woven jersey over his chest before he fired, which showed that death had not been accidental. on a table a loose sheet of paper was found on which had been written these lines to his wife:-- 'dearest lydia,--my brain burns, i _must_ have _walked_; and a fearful dream rises upon me. i cannot bear the horrible thought. god and father of the lord jesus christ, have mercy upon me. dearest lydia, dear children, farewell. my brain burns as the recollection grows. my dear, dear wife, farewell. hugh miller.' it fell to dr. guthrie, in whose church of free st. john's the deceased had been an office member, to apprise the widow of the real nature of the case; and in order to secure her sanction for a _post-mortem_ examination the above letter had to be produced, showing that his purpose had been executed almost before the ink was dry. on the th the verdict was issued:--'from the diseased appearances found in the brain, taken in connection with the history of the case, we have no doubt that the act was suicidal, under the impulse of insanity.' his funeral was the largest edinburgh had seen since that of chalmers, and by his side in the grange cemetery he was laid. to the mass of his countrymen abroad he was the greatest of living scotchmen. his works had given him a european reputation in science, while to those at home the work he had accomplished as a tribune of the people had given him a position second only to that of guthrie. a generation has arisen since which hears but by vague report the principles for which the men of contended. it takes many a man to fall in the ditch before glorious revolutions can successfully march over in their pumps and silk stockings, giving their victorious three-times-three. it has been sought to minimise these issues, to explain them away after the manner of 'able editors' and complacent philosophers cheerfully 'at ease in zion,' and to maintain, with the hardy gravity of ignorance, that the combatants really knew not what they fought for--the headship of christ, anti-patronage, or resistance to the civil courts. similar futilities we have seen ventilated over the american civil war. the north, say the philosophic thinkers, or tinkers, did not know whether it fought for the preservation of the union or against slavery. such speculations are too thin to carry much weight. in both cases many went to their grave for what they believed to be principle, and all such men may be safely trusted to have reached some conclusions and clear issues. these issues obviously all met; after auchterarder on the one hand, and south carolina on the other, had led the way, no such easy subterfuge was possible for either party. the lesson then learned at such a cost might never have been necessary, with a better adjustment of the political balance, which has been again found wanting and craves a final and a rational settlement. what fairfoul in told middleton had been simply again repeated in by muir and hope, who held the ear of sir james graham, to whom peel had resigned the whole management of scottish affairs. for all that graham knew of them, peel might as well have left them to a foreigner. it took the death of thousands of irishmen in the potato famine of to convince the overfed john bull of even the barest existence of an irish question, and many a man went to his grave before lord aberdeen, peel, graham, and other official people could learn for themselves the true condition of scotland. then it was too late, and their regrets were vain. the bill of bolingbroke brought in, as burnet said, to weaken the scottish church, had produced its logical effects in widening the gulf between the people and the nobility of scotland; education at eton, harrow, and the english universities had done the rest. carlyle is known to have regarded the action of the church in as the greatest thing in his time; the sole survivor of the peel ministry, mr. gladstone, has expressed the same opinion; while the critical, wiry, and alert little jeffrey was 'proud of his country.' it bears to-day the mark very strongly of hugh miller. nor need the workman be ashamed of his work--from which, therefore, let him not be separated. chapter v in science 'in league with the stones of the field.'--job v. . the geologist writes in sand literally and historically, and in the science of the testimony of the rocks super-session is the law. 'such,' says miller himself in the preface to the first edition of the _old red sandstone_, 'is the state of progression in geological science that the geologist who stands still but for a very little must be content to find himself left behind.' the advancing tide of knowledge leaves the names of the early pioneers little more than a list of extinct volcanoes. hooke and burnet, ray and woodward, moro and michel, are to the ordinary mass of readers about as obsolete as the saurian and the mastodon. only the very few can live in a tide so strong, which bears away not only the older landmarks but even such names as werner and hutton, hall and fleming. from about to the old metaphysical reign seems to have ceased; and jeffrey, in the palmy days of the _edinburgh review_, could declare that the interest in psychology had well-nigh passed away with dugald stewart. natural science seemed to be taking its place, and the british association movement lent impetus to the new _régime_. sedgwick, buckland, murchison, owen, and others, followed by huxley and tyndall, appeared to herald the advent of an age when the most difficult problems could be read off the book of nature, and the public turned eagerly from the babel of the philosophers to the men of the new school in a sort of expectation of a royal road to learning, without missing their way in theological jungle or 'skirting the howling wastes' of metaphysics. needless to say, the hopes were no more realised than were the expectations of a golden age of material prosperity in the wake of the reform bill. the problem of man and his destiny remains as rooted as ever, and the metaphysician has not been dislodged. the old battle of the evidences had been fought in the domain of mental science, and when transferred to the natural sciences the fight was not productive of the expected results. the times, as richter said, were indeed 'a criticising critical time, hovering between the wish and the ability to believe, a chaos of conflicting times: but even a chaotic world must have its centre, and revolve round that centre: there _is_ no pure entire confusion, but all such presupposes its opposite, before it can begin.' in scotland and in england the great ecclesiastical currents of the disruption and the oxford movement had left the nation for a time weary of theology, and the school of natural science was in possession of the field. now the tide has turned, and the geologist is threatened with eclipse. of the _doyen_ of the new school, richard owen, professor huxley says:--'hardly any of those speculations and determinations have stood the test of investigation. i am not sure that any one but the historian of anatomical science is ever likely to recur to them. obvious as are the merits of owen's anatomical and palæontological work to every expert, it is necessary to be an expert to discuss them; and countless pages of analysis of his memoirs would not have made the general reader any wiser than he was at first.' even buckland is regarded by boyd dawkins as belonging to a type of extinct men. thus is the deposition effected of the scientific pope of the day. if such rapid supersession be the law, who can expect in departing to leave footprints in the annals of so shifting a science? who can be a fixed star? there is some comfort in the reflection that, as in political economy, so in geology, it is the inspiration that lives and not the mere amount of positive contribution to knowledge. bacon has effected nothing for science; in everything that he attempted it may be shown that he was wrong and that his methods have led to nothing. his name is associated with no new discovery, no new law, not even with a new or inductive method. but his niche is secure through the spirit in which he approached the question; if he did not see the promised land, at least he was a firm believer in its existence, and that spirit has outlived his unhappy detraction of greater men than himself in mental philosophy. his mind was swift to perceive analogies, and such a type of mind, if it adds little to actual knowledge, is at least valuable as a stimulus. carlyle in his political pamphlets has certainly not advanced the lines of the 'dismal science'; he even contemptuously doubted its existence, and he has done harm to it through the ready-reckoner school of _à priori_ economists who refer everything with confidence to their own internal consciousness. yet carlyle at his worst has his value. he has the merit of showing that the problem is in its very nature an everlasting one, and that the plummet line of the mere profit-and-loss moralist will never sound the depths of man and his destiny. such thinkers are, however, rare; but in natural science they are the salt. such are oken, cuvier, darwin; their position is independent of the truth of their theories, and they have the gift of a fused and informing imagination, by which their theories are landmarks. much of their work has already been recast, and some of their once supposed safest generalisations have been abandoned. but the progress of science revolves round them as central suns. hardly one of niebuhr's interpretations of roman history has stood the test of subsequent investigations, any more than those of ewald in the field of biblical criticism. yet in historical science no two men have a more assured rank. it is this informing power that keeps alive the geologist. hume owes his position in metaphysics to this power, and to his great gifts as a stylist. few men of science have had graces of style. in darwin it is lacking, and he has himself set on record that literature and art had ceased for him to exert any influence, and that a mere novel had become the highest form of intellectual amusement. hutton needed a playfair to make him intelligible, as dugald stewart was needed for the exposition of reid. but it is this power that will keep miller alive. his views upon the old red sandstone, on the noachian deluge, on the mosaic cosmogony, may be right or wrong. but they have the sure merit of abiding literature, and men highly endowed with this gift have a lasting and assured fame. mr. lowell has declared clough to be the true poet of the restlessness of the later half of the century, and tennyson to be but its pale reflex. but the answer is ready and invincible: tennyson is read, and clough is already on the shelf. as a piece of imaginative writing, _the old red sandstone_ is not likely to be soon surpassed in its own line. 'i would give,' we find buckland declaring, 'my left hand to possess such powers of description as this man has.' 'there is,' says carlyle, 'right genial fire, everywhere nobly tempered down with peaceful radical heat, which is very beautiful to see. luminous, memorable; all wholesome, strong, fresh, and breezy, like the "old red sandstone" mountains in a sunny summer day.' we doubt if a single page of sedgwick, or of buckland even in his _bridgewater treatise_, be read--at least as literature. but a man, whose book upon the 'old red' has seen its twentieth edition, whose _testimony of the rocks_ is in its forty-second thousand, and whose _footprints_ has seen a seventeenth edition, has only attained this popularity by his solid merits as a writer and thinker. mere popularisation cannot explain it. when a man has fully mastered his subject, and his subject has mastered him, there is sure to emerge a certain demonic force in literature or in science, all the more if the writer be a man with a style. it need hardly be said that geology, from its very first appearance, had been associated with distinct views in biblical criticism. the old chronology of archbishop ussher in the margin of the authorised version, by which b.c. was gravely assigned as the date of the creation of the world, and b.c. for the deluge, was in conflict with a science which required ages for its operations and not the limited confines of six thousand years, which form but a mere geological yesterday to the scientist like lyell, who postulates some eighty millions of years for the formation of the coal-beds of nova scotia. the six 'days' of the biblical creation were thought unworthy, as a mere huddling of events into a point of time, of the divine wisdom, and impossible in conception. mistakes in positive statement, no less than of implication, were also alleged against the mosaic record, which was said to be admirable as literature if not immaculate in science. for long geology was regarded as a hostile intruder, and it required much time to assuage the fears on the one hand and lessen the rather vague pretensions on the other, before the lines of demarcation could be firmly drawn, if indeed, in a certain class of both theological and scientific minds, they can be said to be even yet settled. there is still the voltairian type of thinker which is not yet exploded; and which, even in the case of professor huxley, has imagined that a mere shaking of the letter of a text or two is tantamount to an annihilation of the christian faith. 'that the sacred books,' as carlyle says, 'could be all else than a bank of faith bill, for such and such quantities of enjoyment, payable at sight in the other world, value received; which bill becomes a waste paper, the stamp being questioned; that the christian religion could have any deeper foundations than books, nothing of this seems to have even in the faintest matter occurred to voltaire. yet herein, as we believe the whole world has now begun to discover, lies the real essence of the question.' science, in fact, after a long _régime_ of even more than macaulayesque cocksureness, is now abating its tone. it now no longer threatens like a second flood to cover the earth, and it is possible for mental and historical science to reappear like the earth out of the waters, and a clear line to be drawn between the limits of mind and matter. happily, accordingly, it is no longer possible for a voltaire to meet the theologian with a belief that the shells found on high hills were dropped by pilgrims and palmers from the holy land, any more than it would be possible to assert, with dugald stewart, that the words in sanskrit akin to greek were dropped by the troops of alexander the great. it is now as impossible to maintain, with the mythologists of legend, that the ross-shire hills were formed by the _cailliach-more_, or great woman, who dropped stones through the bottom of the panniers on her back, as it would be for any reactionary chauteaubriand to assert that god made the world, at the beginning, precisely as we see it with all its completeness and antiquity, since he believed an infancy of the world would be a world without romance!--denying creation in periods, and asserting it in instantaneous processes, by which the fossils were even created just as we see them. such a conception is not to exalt the divine power; or, if it appears to do so, it yet effectively annihilates a belief in the divine wisdom that could create pretty toys and useless fossils--a creation of mummies and skeletons that were never from the very beginning intended to be anything but skeletons, without any relation to living beings. miller accordingly makes it perfectly plain in what spirit he approaches the sacred record. the bible, he says repeatedly, is neither a scientific text-book nor even a primer. why, he asks, should it be regarded as necessary to promulgate the truths of geology when those of astronomy have been withheld? 'man has everywhere believed in a book which should be inspired and should teach him what god is and what god demands of him, and this expectation is fully met in the bible. but nowhere has man looked for the divine revelation of scientific truth, for it is in accordance with the economy of providence, that providence which is exhibited in gradual developments, that no such expectation has been or need be realised, the _principia_ of newton and the discoveries of james watt being both the result of the natural and unaided faculties of man.' nay, more; there never could have been such a revelation given, for never yet has a single scientific truth been revealed. but, on the other hand, when he contrasts this clear perception of the demarcation of religion and science in the bible, and the all too copious neglect of it in the other sacred books of the world, he is constrained to regard this very ability of distinction between two classes of truth as a strong argument for its inspiration. on man and his destiny he is no less clear, and he has many fertile suggestions to offer. his main thesis in this connection we have already seen as determining in his own life its central point. man he regards as literally the fellow-worker with god. up till his appearance upon the earth, nature had been remarkable only for what it was, but not for what it became. the advent of man marks the improver of creation--god made manifest in the flesh. between his intellect and that of his creator there is a relation, since we find creature and creator working by the same methods. precisely as we see china arriving at the invention of printing, gunpowder, and the mariner's compass without any connection with the west, so we see the works of the creator in the palæozoic period repeated by the tiny creature-worker, without any idea that he had been anticipated. thus creation is not merely a scheme adapted to the nature of man, but one specially adapted to the pattern nature of god. man made in the image of god is a real and fitting preparation for god's subsequent assumption of the form of man. 'stock and graft had the necessary affinity,' and were finally united in the one person. history is, therefore, no mere finite record dating from a human act in eden, but is the real result of a decree, 'in which that act was written as a portion of the general programme.' the problem of the origin of evil is of course a difficulty viewed in relation to the decrees of god, in whom no evil can exist. in the present state of things he regards evil as due to man himself. the deputed head of creation has voluntarily and of his own free will _not_ chosen to be a fellow-worker with god, who, while binding him fast in the chain of events, has yet left his will free. to ordain sin would be a self-contradiction of the idea of god; he but creates the being that in turn creates sin. 'fore-knowledge,' as milton says, 'had no influence on their fault, which had no less proved certain unforeseen.' perhaps this is as near as we are ever likely to get. but the fall in its theological aspect, while it must be fully apprehended by faith, has nothing to fear from science, which teaches, if it can be said emphatically to teach one thing, that the sins of the fathers are visited upon the children. with coleridge, therefore, he regards the fall as a necessary stage in the history of thought and of man. the creation of the non-absolute gives a pivot without which all subsequent events would be inexplicable. it gives the true means of colligating the phenomena: man, if at the fall he lost eden, gained a conscience and a moral sense. more remarkable is his attempted reconciliation of science and the mosaic cosmogony. chalmers had regarded the biblical account as relating only to existing creations, and believed in the existence of a chaotic period of death and darkness between this present world and the prior geological ages. pye smith, on the other hand, had regarded chaos as both temporary and limited in extent, and believed that outside this area there had existed lands and seas basking in light and occupied by animals. but subsequent geological knowledge had shown that this theory of cataclysms and breaks was without evidence--many of the present plants and animals co-existing with those of the former periods; nor could smith's theory of light existing round the coasts of the earth be brought to square with the distinct statement of the primal creation of light in genesis. on the other hand, miller notices that geology, as dealing not with the nature of things, but only with their actual manifestations, has to do with but three of the six days or periods. the scale of all geologists is divided into three great classes. lesser divisions of systems, deposits, beds, and strata may exist; but the master divisions, as he calls them, are simply those three which even the unpractised eye can detect--the palæozoic, the secondary, and the tertiary. the first is the period of extraordinary fauna and flora--the period emphatically of forests and huge pines, 'the herb yielding seed after its kind, and tree bearing fruit.' the second is the age of monsters, reptiles, pterodactyls and ichthyosaurs, 'the fowl that flieth above the earth, the great sea-monsters and winged fowl after its kind.' the tertiary period is that of 'the beasts of the earth and the cattle after their kind.' in each age, it is true, there is a twilight period, a period of morning-dawn and evening-decline; but in the middle of each period it is that we find the great outstanding features above. thus there would be no contradictions in the record. this, it must be allowed, summarises truly enough the process of creation; but it leaves out of sight the invertebrata and early fishes of the first period, and regards the succeeding carboniferous era as the leading features, while perhaps in some subordinate details it inverts the order of other appearances. to the wider objection to the biblical record, with its light before the creation of the sun upon the fourth day, the vegetation on the third independent of the sun's warming rays, and to other real or supposed contradictions, miller has a highly ingenious reply. we do not think it fully meets the necessities of the case, but it has unquestionably the merit of imaginative power, and is in full harmony with the nature of man's mind, and is therefore preferable to any theory which would assert the exact science of the mosaic record by its anticipation of the theory of laplace and herschel, by which the earth existed before the sun was given as a luminary, and was independent of the sun for light. perhaps the theory of progressive revelation will commend itself to most as the truest and the simplest explanation, though it should be noted that the extraordinary approximation of the biblical version to the latest science does really set it far above the merely human speculation of some old hebrew newton or descartes. while regarding the 'days' as ages, miller views the record as the result of an _optical vision_ presented to the writer. he truly enough remarks that any exact revelation would have defeated its own object through an elaborate statement to man at an early stage. man would not have believed it, as it would have contradicted his own experience. he would no more have believed that the earth revolved on its own axis than that molluscs had preceded him on the earth. the record, therefore, he regards as according to appearance rather than to physical realities: 'the sun, moon, and stars may have been created long before, though it was not until the fourth day of creation that they became visible from the earth's surface.' the six days or periods he takes to correspond with the six divisions in a successive series of the azoic, silurian, carboniferous, permian, oolitic, and tertiary ages. to the human eye of the seer, the second day would afford nothing to divert it from the atmospheric phenomena; on the fourth the celestial phenomena would alone be so prominent as to call for specific mention. but, familiar to most readers as the famous passage is, we here present it as the best example of his descriptive and imaginative powers. if there are to be reconciliations at all, as either necessary or desirable, it would be hard to beat this fine piece of fused strength and imagination.[ ] [ ] _testimony of the rocks_, pp. - , ed. . 'such a description of the creative vision of moses as the one given by milton of that vision of the future which he represents as conjured up before adam by the archangel, would be a task rather for the scientific poet than for the mere practical geologist or sober theologian. let us suppose that it took place far from man, in an untrodden recess of the midian desert, ere yet the vision of the burning bush had been vouchsafed; and that, as in the vision of st. john in patmos, voices were mingled with scenes, and the ear as certainly addressed as the eye. a "great darkness" first falls upon the prophet, like that which in an earlier age fell upon abraham, but without the "horror"; and as the divine spirit moves on the face of the wildly troubled waters, as a visible aurora enveloped by the pitchy cloud, the great doctrine is orally enunciated, that "in the beginning god created the heavens and the earth." unreckoned ages, condensed in the vision to a few brief moments, pass away; the creative word is again heard, "let there be light," and straightway a grey diffused light springs up in the east, and, casting its sickly gleam over a cloud-limited expanse of steaming, vaporous sea, journeys through the heavens towards the west. one heavy sunless day is made the representative of myriads; the faint light waxes fainter--it sinks beneath the dim undefined horizon; the first scene of the drama closes upon the seer; and he sits a while on his hill-top in darkness, solitary but not sad, in what seems to be a calm and starless night. 'the light again brightens--it is day; and over an expanse of ocean, without visible bound, the horizon has become wider and sharper of outline than before. there is life in that great sea--invertebrate, mayhap also ichthyic, life; but, from the comparative distance of the point of view occupied by the prophet, only the slow roll of its waves can be discerned, as they rise and fall in long undulations before a gentle gale; and what most strongly impresses the eye is the change which has taken place in the atmospheric scenery. that lower stratum of the heavens occupied in the previous vision by seething steam, or grey, smoke-like fog, is clear and transparent; and only in an upper region, where the previously invisible vapour of the tepid sea has thickened in the cold, do the clouds appear. but there, in the higher strata of the atmosphere they lie, thick and manifold--an upper sea of great waves, separated from those beneath by the transparent firmament, and, like them too, impelled in rolling masses by the wind. a mighty advance has taken place in creation; but its most conspicuous optical sign is the existence of a transparent atmosphere--of a firmament stretched out over the earth, that separates the water above from the waters below. but darkness descends for the third time upon the seer, for the evening and the morning have completed the second day. 'yet again the light rises under a canopy of cloud, but the scene has changed, and there is no longer an unbroken expanse of sea. the white surf breaks, at the distant horizon, on an insulated reef, formed mayhap by the silurian or old red coral zoophytes ages before, during the bygone yesterday; and beats in long lines of foam, nearer at hand, against the low, winding shore, the seaward barrier of a widely-spread country. for at the divine command the land has arisen from the deep--not inconspicuously and in scattered islets, as at an earlier time, but in extensive though flat and marshy continents, little raised over the sea-level; and a yet further fiat has covered them with the great carboniferous flora. the scene is one of mighty forests of cone-bearing trees--of palms and tree-ferns, and gigantic club-mosses, on the opener slopes, and of great reeds clustering by the sides of quiet lakes and dark rolling rivers. there is a deep gloom in the recesses of the thicker woods, and low, thick mists creep along the dank marsh or sluggish streams. but there is a general lightening of the sky overhead; as the day declines, a redder flash than had hitherto lighted up the prospect falls athwart fern-covered bank and long withdrawing glade. and while the fourth evening has fallen on the prophet, he becomes sensible, as it wears on, and the fourth day approaches, that yet another change has taken place. 'the creator has spoken, and the stars look out from openings of deep unclouded blue; and as day rises, and the planet of morning pales in the east, the broken cloudlets are transmuted from bronze into gold, and anon the gold becomes fire, and at length the glorious sun arises out of the sea, and enters on his course rejoicing. it is a brilliant day; the waves, of a deeper and softer blue than before, dance and sparkle in the light; the earth, with little else to attract the gaze, has assumed a garb of richer green; and as the sun declines amid ever richer glories than those which had encircled his rising, the moon appears full-orbed in the east,--to the human eye the second great luminary of the heavens,--and climbs slowly to the zenith as night advances, shedding its mild radiance on land and sea. 'again the day breaks; the prospect consists, as before, of land and ocean. there are great pine woods, reed-covered swamps, wide plains, winding rivers, and broad lakes; and a bright sun shines over all. but the landscape derives its interest and novelty from a feature unmarked before. gigantic birds stalk along the sands, or wade far into the water in quest of their ichthyic food; while birds of lesser size float upon the lakes, or scream discordant in hovering flocks, thick as insects in the calm of a summer evening, over the narrower seas, or brighten with the sunlit gleam of their wings the thick woods. 'and ocean has its monsters: great _tanninim_ tempest the deep, as they heave their huge bulk over the surface to inhale the life-sustaining air; and out of their nostrils goeth smoke, as out of "a seething pot or caldron." monstrous creatures, armed in massive scales, haunt the rivers, or scour the flat rank meadows; earth, air, and water are charged with animal life; and the sun sets on a busy scene, in which unerring instinct pursues unremittingly its few simple ends--the support and preservation of the individual, the propagation of the species, and the protection and maintenance of the young. 'again the night descends, for the fifth day has closed; and morning breaks on the sixth and last day of creation. cattle and beasts of the field graze on the plains; the thick-skinned rhinoceros wallows in the marshes; the squat hippopotamus rustles among the reeds, or plunges sullenly into the river; great herds of elephants seek their food amid the young herbage of the woods; while animals of fiercer nature--the lion, the leopard, and the bear--harbour in deep caves till the evening, or lie in wait for their prey amid tangled thickets, or beneath some broken bank. at length, as the day wanes and the shadows lengthen, man, the responsible lord of creation, formed in god's own image, is introduced upon the scene, and the work of creation ceases for ever upon the earth. 'the night falls once more upon the prospect, and there dawns yet another morrow--the morrow of god's rest--that divine sabbath in which there is no more creative labour, and which, "blessed and sanctified" beyond all the days that had gone before, has as its special object the moral elevation and final redemption of man. and over _it_ no evening is represented in the record as falling, for its special work is not yet complete. such seems to have been the sublime panorama of creation exhibited in vision of old to "the shepherd who first taught the chosen seed, in the beginning how the heavens and earth rose out of chaos"; and, rightly understood, i know not a single scientific truth that militates against even the minutest or least prominent of its details.' the _origin of species_ in was issued after miller's death, but the leading doctrines of darwin were not unknown before that time to the public through the appearance of robert chambers's _vestiges of the natural history of creation_ in , and a subsequent volume of 'explanations' in . this book caused almost as considerable a stir as that of darwin himself, and the greatest care was taken by chambers to conceal the authorship. the proof-sheets sent to mr. ireland in manchester, were returned to the writer, who reforwarded them to ireland, who in his turn despatched them to london. the guesses at the author ranged from sir charles lyell up to the prince consort; and so strong were the feelings aroused that they defeated a proposal to bring in chambers as lord provost of edinburgh in , and the secret was not formally divulged till the issue by ireland in of a twelfth edition. the book is written in a 'powerful and brilliant style,' as darwin says; and, though long out of print, its re-issue by routledge and son in their universal library has again drawn attention to its views, which in scotland caused something of the stir produced by the appearance in england of _essays and reviews_. chambers, indeed, regarded his book as 'the first attempt to connect the natural sciences into a history of creation. as such, it must necessarily be crude and unsatisfactory, yet i have thought the time was come for attempting to weave a great generalisation out of established natural truths.' much of the popular ideas or misconceptions about the geological record is due to the _vestiges_. it is not very strong in logic nor exact in individual branches of science, yet its influence fully merited the detailed reply by miller, in , in the _footprints of the creator_, which he appropriately dedicated to sir philip egerton, the highest authority on fossil fishes. chambers and his school had largely subscribed to the doctrines of oken, by which no organism had been created of larger size than an infusorial point, and no organism created which was not microscopic; whatever exists larger, man himself included, having been developed and not created. to this miller replies that this at least is not the testimony of the rocks. if it were true, it would follow that the oldest fossils would be small, and low in organisation. but, so far is this from being the case that the oldest organisms, whether that be the _asterolepis_ or the _cephalaspidæ_ or the _acanthidæ_, are large and high. one asterolepis found at thurso measures over twelve feet, and a russian specimen described by professor asmus of dorpat seems to have reached the astonishing length of twenty-three feet. thus, the earliest organisms 'instead of taking their place, agreeably to the demands of the development hypothesis, among the sprats, sticklebacks, and minnows of their class, took their place among its huge and basking sharks, gigantic sturgeons, and bulky sword-fishes. they were giants, not dwarfs.' the prevalence of the brachiopods in the silurian period over the _cephalaspidæ_ proves little. what the naturalist has to deal with is not quantity but quality, 'not the number of the low, but the standing of the high. a country may be distinctly a country of flocks and herds, or a country of carnivorous mammalia, or like new south wales or the galapagos, a country of marsupial animals or of reptiles. its human inhabitants may be merely a few hunters or shepherds, too inconsiderable in numbers to give it any peculiar standing as a home of men. but in estimating the highest point in the scale to which the animal kingdom has attained, it is of the few men, not of its many beasts, that we must take note.' thus he maintains that the existence of a single cephalopod or one cuttlefish among a wilderness of brachiopods is sufficient to indicate the mark already attained in the scale of being, just as the existence of the human family, when restricted to a pair, indicated as clearly the scale as when its existence can be counted by millions. under the clearing-system in the western highlands, miller had, during 'the cruise of the betsey,' noticed in the island of rum a single shepherd and eight thousand sheep. yet the human unit, to the naturalist, would outweigh all the lower organisms. moreover, the brachiopods of the palæozoic age he would regard as larger than those existing now which have sunk by 'degradation' into inferior importance. the proof of the development theory in the realm of fossil flora he would regard as still more questionable. it had been asserted that in the carboniferous age no exogenous plant had appeared; that before the lias nature had not succeeded in producing a tree, and that the vegetation of the coal-measures had been 'magnificent immaturities' of the vegetable kingdom. but the quarry of craigleith, near edinburgh, alone would refute it, not to speak of the coal-fields of dalkeith and falkirk with their araucarians and pines. while brongniart had denied to the lower 'old red' anything higher than a lichen or a moss, 'the ship carpenter might have hopefully taken axe in hand, to explore the woods for some such stately pine as the one described by milton: "hewn on norwegian hills, to be the mast of some great ammiral."' it might be thought, however, that to the geological argument from development some consolation might be left from the general fact of the lower producing the higher. yet even here the lamarckian theory fails. fishes were earlier than the beasts of the field and man. but we are still a long way from any proof that 'the peopling of the earth was one of a natural kind, requiring time'; or that the predecessors of man were his progenitors. so far as geology is concerned, superposition is not parental relation, so that there is no necessity for the lower producing the higher. nor has transmutation of marine into terrestrial vegetation been proved. this had been the mainstay of the lamarckian hypothesis, and had been adopted from the brilliant but fancifully written _telliamed_ (an anagram, by the way, of the author's name) of de maillet by both oken and chambers, who had found in the _delphinidæ_ the marine progenitors of the _simiadæ_, and through them of man--a curious approximation to some recent crude ideas of professor drummond in his _ascent of man_. they had pointed to the general or supposed agreement in fauna and flora between the galapagos and south america, between the cape de verde islands and africa; yet in such a period of conversion plants of an intermediate character would be found, and thousands of years have failed to produce such a specimen. thus geology, botany, and zoology would seem to afford slight support to the darwinian theory, at least in the state of the argument as presented in the _vestiges_, unless a very large draft upon the mere imagination is made. and such a demand is made by darwin. 'if,' says he, 'my theory be true, it is indisputable that before the lowest silurian stratum was deposited, long periods elapsed, as long as, or probably far longer than, the whole interval from the silurian age to the present day; and that, during these vast, yet quite unknown periods of time, the world teemed with living creatures.' this, however, we may say with the regent morton, is only 'a devout imagination'; and it might be more scientific to take the geological record as we find it, for, says miller, 'it is difficult to imagine that that uniform cessation of organised life at one point, which seems to have conducted sir roderick murchison and professor sedgwick to their conclusion, should thus have been a mere effect of accident. accident has its laws, but uniformity is not one of them; and should the experience be invariable, as it already seems extensive, that immediately beneath the fucoidal beds organic remains cease, i do not see how the conclusion is to be avoided, that they represent the period in which, at least, _existences capable of preservation_ were first introduced.' indeed the hypothesis of darwin would fall under the remark of herodotus, that the old theorisers and speculators at the last resort betook themselves to a belief in an imaginary ocean-river or to something in the interior of the earth where observation was of necessity excluded. for, as professor bain says, the assertion of a fact wholly beyond the reach of evidence for or against, is to be held as untrue: we are not obliged to show that a thing is not,--the burden lies on them who maintain that the thing is. we have said that those who ultimately live in each branch of science are few. it is only by the combination in perfection of imagination and observation that success is ensured. miller had noticed in the writer of the _vestiges_ the absence of original observation and abstract thinking, or the power of seeing and reasoning for himself. in truth, there is something in geological speculation akin to what professor jebb has noticed in the field of classical emendation and of textual criticism, especially in germany, where scholarship is a crowded profession, and eminence is often temporarily won by boldness of handling the texts. but even ritschl, with all his heavy apparatus of learning, singularly fails in comparison with the sagacity of bentley or the instinct of porson. what habits of classical verse-composition had done for these scholars is brought to the geologist by observation. this, in unison with creative mental power, will alone preserve the name of the natural scientist. the first has kept white of selborne a literary evergreen: the second has maintained his place for cuvier. miller's own friend, dr. longmuir, rightly singles out this champollion-like trait of _sagacity_ as his most characteristic feature, by which 'he seemed by intuition to perceive what cost other minds no small amount of careful investigation.' he was very cautious in statement, and laborious in the acquisition of his data. in his works the reader will find no second-hand statements, no airy generalisation; even in fields where special research in minute departments had been by circumstances denied to him, his gift of constructive imagination often enables him to supply such defects as later investigators may have detected and added. 'the more,' says professor huxley, i study the fishes of the old red, the more i am struck by the patience and sagacity manifested in his researches, and by the natural insight which, in his case, seems to have supplied the want of special anatomical knowledge.' and what is true in science is also no less true in his purely literary performances. the reader of his articles, political or social, cannot fail to be struck with the pertinence of his quotations and illustrations. what he knew was instantly at the call of a powerful memory and a vigorous imagination. as an editor, he had not to go to memory for his metaphors, and to his imagination for his facts. both came easily and naturally; and his writing, even in its most sustained flights, shows no signs of effort. some critics have detected in his style an element of exuberance; and this may be allowed in his narrative and descriptive passages. there would appear to have been, as it were, a celtic lobe of imagination in his mind for the feeling of discursive description and external nature. thus, in his slightest landscapes his imagination or eye is not satisfied with the few bold touches such as carlyle would, after his manner, throw upon the canvas. it expands, like the method of ruskin, over the surface. but in each case the defect is the result of original endowment. the eye, he says, had been in his case exclusively trained as a mason, and this habit of seeing the projected line complete from the beginning was at the bottom of his often spoiling the effect of his narrative with flamboyant additions, through his possession of the geological eye for its conformation in detail. johnson said of thomson that he had a true poetical genius--the power of seeing even a pair of candles in a poetical light. the landscape became to miller at once anatomised into its geological aspects. but in his strictly scientific passages this is not so. there the style is simple in expression and close in reasoning. when we consider the great amount of solid literary performance, and of minute observation, recorded in his _cruise of the betsey_ and his _rambles of a geologist_, extending over the west coast and the orkneys--when we know that much of his work consisted of papers in _the witness_, republished, like _the old red sandstone_, in book form with the necessary additions, we shall wonder at the fertility and the quickness of the mind that could, in the midst of distracting journalistic demands on his time and attention, produce such a mass of varied and finished work in science and literature. and of the work in _the witness_ as a political writer, we need only say that the present ecclesiastical condition of scotland bears largely his impress. till he came and gave expression to the feeling of the country in the columns of his paper, the people had to a considerable extent believed the question at issue to be one that concerned mainly the clergy. this had been the standpoint of the moderate organs, in a wary attempt to win over the laity. but by the _letter to brougham_ he won the ear of the people, and to the end he never lost it. by the political candidates in scotland at the general election had proclaimed themselves, with a single exception, in favour of some distinct alteration of the law of patronage. whether church papers are or are not a blessing--in england they have become a menace to political action and a medium for the most offensive clericalism and reactionary measures--may safely be left out of account in settling the question in his own case, for, as we have seen, he had never consented to make his paper a merely ecclesiastical organ. but of the work which he accomplished as a leader-writer and as an exponent of popular rights we have the unhesitating estimate of guthrie: 'the battle of christ's rights as head of the church, and of the people's rights as members of the body of which he is the head, was fought and won in every town and a large number of the parishes of scotland, mainly by hugh miller, through the columns of _the witness_ newspaper.' of it he himself, in the closing sentences of the _schools and schoolmasters_, could say with modesty that it took its place among our first-class scottish newspapers, and that it numbered among its subscribers a larger percentage of readers with a university education than any other. nor would he, perhaps, have considered it as among the least of his journalistic successes that his name and connection could win for the elder bethune, at the close of his wintry day, the proposed editorship of the _dumfries standard_, which would have done much to have brightened the life of his old fellow-contributor to wilson's _border tales_ had not the poet been removed before him by death. in science there are stars and stars, to borrow the adage of thackeray upon men. there are stars that are fixed. in his own line of geology, as an inspirationist, we think his name will not soon pass away. there may be defects of knowledge, but there is no defect of spirit; and here we cannot do better than set down the opinion of his friend, sir archibald geikie, who has a connection both with miller and with murchison through his occupancy of the murchisonian chair of geology in the university of edinburgh. both miller and murchison came out of the black isle. in a communication to us of the date nd december , he thus writes:-- 'hugh miller will always occupy a peculiar place in the history of geology, and in the ranks of geological literature. he was not in any sense a trained geologist. he lacked the habit of patient and detailed investigation in departments of the science that did not specially interest him, but which were essential as a basis of accurate induction and successful speculation. in all that relates to the stratigraphical sequence of the formations, for example, he accepted what had been done by others without any critical examination of it. thus, in his own region--the north of scotland--he believed that a girdle of old red sandstone nearly encircles the older crystalline rocks of ross and sutherland--a view then generally adopted. yet he had actually walked over ground where, with even an elementary knowledge of structural geology, he could have corrected the prevalent error. it is, of course, no reproach to him that he left matters as he found them in that respect; his genius did not find in such questions the appropriate field of its exertion. 'nor though he occupied himself all through his life with fossils, can he be called a palæontologist. he had no education in comparative anatomy, and was thus incompetent to deal adequately as a naturalist with the organisms which he discovered. he was himself perfectly conscious of the limitations of his powers in this department, and thus wisely refrained from burdening the literature of science with descriptions and names which would have been revised, and perhaps entirely recast, by some subsequent more competent biologist. 'hugh miller's unique position is that of a poetic student of the geological side of nature, who possessed an unrivalled gift of vividly communicating to others the impressions made on his own mind by the observation of geological fact and by the inferences which such observation seemed to warrant. his lively imagination led him to seize more especially on those aspects of the past history of the earth which could be most vividly realised. he loved to collect the plants and animals of which the remains have been entombed among the rocks, and to re-people with them the scenes in which they lived long ages ago. each scattered fact was marshalled by his eager fancy into its due place in the mental picture which he drew of such long-vanished lands, lakes, rivers, and seas. his enthusiasm supplied details where facts were wanting, and enabled him to kindle in his readers not a little of the burning interest which he felt himself. 'long study of the best english literature had given miller a rare mastery of his mother tongue. for elegance of narrative combined with clearness and vividness of description, i know no writing in the whole of scientific literature superior, or, indeed, perhaps equal to his. there can be no doubt that this literary gift, appealing as it did to so wide a circle of readers, formed a chief source of the influence which he exerted among his contemporaries. it was this that enabled him to spread so widely a curiosity to know something of geological science, and an interest in the progress of geological discovery. i do not think that the debt which geology owes to him for these services, in deepening the popular estimation of the science, and in increasing the number of its devotees, has ever been sufficiently acknowledged. during his lifetime, and for some years afterwards, hugh miller was looked upon by the general body of his countrymen as the leading geologist of his day. and this exaggerated but very natural estimate spread perhaps even more extensively in the united states. his books were to be found in the remotest log-hut of the far west, and on both sides of the atlantic ideas of the nature and scope of geology were largely drawn from them. 'of the extent and value of miller's original contributions to geology i am, perhaps, hardly fitted to speak. he was one of my earliest and kindest scientific friends. he used to relate to me the results of his summer rambles before he had time to set them down in writing. he admitted me into the intimacy of his inner thoughts on geological questions and controversies. he brought me completely under the spell of his personal charm, and filled me with an enthusiastic love for the man as well as a passionate admiration for the geologist. nor has the glamour of that early friendship passed away. i would rather leave to others the invidious task of coldly dissecting hugh miller's work and seeing how much of it has been a permanent addition to science, and how much has passed away with the crudities of advancing knowledge. i will only say that there cannot be any doubt that his contributions to the stock of geological fact were much less important than the influence which his writings ever had in furthering the spread of an appreciation of geological science throughout the english-speaking world. 'there were two departments in which his best original work was done. one of these was the old red sandstone, where he laid the foundations of his fame as an observer and describer of nature. his unwearied devotion to the task of collecting the fishes of the old red sandstone, and his patient industry in piecing their broken fragments together, opened up a new chapter in the history of life on our globe. the other department was that which embraces the story of the ice age. miller was one of the pioneers in the study of the boulder-clay. the last years of his life were more especially devoted to that interesting formation in which he found fossil shells in many parts of scotland where they had never been found before. i well remember my last interview with him, only a few evenings before his death. he had spent a short holiday in the low ground about bucklyvie between the forth and clyde, and had collected a number of marine shells, which led him to draw a graphic picture of what must have been the condition of central scotland during a part of the glacial period. on the same occasion he questioned me as usual about my own geological doings. i had been surveying in detail the geological structure of arthur's seat at edinburgh, and showed him my maps. he went over them with lively comments, and, when he had done, turned round to his eldest daughter, then a girl at school, and gave her in his own pictorial way a sketch of the history of the volcano that had piled up the picturesque hill on the eastern outskirts of the city. 'i count it as one of the privileges of my life to have known hugh miller, and as one of its chief losses that he was so suddenly removed when i had hardly realised the full value of his friendship and of his genial enthusiasm. his writings formed my earliest geological text-books, and i shall never cease to look back upon their influence with gratitude. they ought to be far more widely read than they seem now to be. assuredly no young geologist will find more stimulating chapters than those penned by the author of the _old red sandstone_.' the statue erected to him by his countrymen presents to the eye of the traveller one of the most striking features of the landscape as he approaches the little town of cromarty. no more fitting scene could be found than that which commands the magnificent sweep of water over which miller's eye had ranged when a boy. of the scott monument in edinburgh he had said that no monument could be in keeping and in character that was not gothic; and no one to himself could be true that forgot the interpreter of the old red sandstone. as late as , buckland in his _bridgewater treatise_ had briefly dismissed it, and it was a new revelation in geology to make known its scientific importance. in dedicating the book to sir roderick murchison, who had been born at taradale on the beauly firth in , he could say that smith, the father of english geology, had been born upon the oolite: they, he added, had been born upon the old red. rarely could nature afford a more striking example of the true and the picturesque, than in these two widely differing memorials, the one in the princes street of his 'own romantic town,' the other looking over the expanse of the cromarty firth. in life these men had never met, and in type they were totally distinct. yet in the great features of integrity and force of character no two men could more strikingly agree. both wrote with their eyes on the object, and both were loyal to fact. of miller we may say what carlyle had said of sir walter, that no sounder piece of british manhood had been put together in this century of time, and that, when he departed, he took a man's life along with him. a man of the people, he was understood by the people; and he wished it to be so. when we passed through the sutors of cromarty some years ago, about six in the morning of a fine summer day, there was a sailor at the wheel on the bridge. under the belief that we were strangers to the locality, he pointed out the statue in the distance and gave an account, correct in the main, of what miller had been and what he had done. in dwelling upon the life the narrator seemed to borrow respect for the dignity of all labour and of his own calling. goldsmith thought of burke that in giving up to party what was meant for mankind he had narrowed his mental powers and lessened his influence and force. it may be that there are some who think that, in doing the ecclesiastical work which he accomplished, he had given up to the church of scotland in all her branches what was meant for science. such a judgment would be incorrect; it would certainly be one which would but feebly reflect the convictions of all scotchmen. it is a true remark of the elder disraeli that few men of science have either by their work or in their life influenced the staple of the thinking of humanity. to influence a whole people is certainly given but rarely to any one man. but to mould the opinions of his countrymen in a lasting sense,--and no higher object would he have desired--was no less certainly given to hugh miller. bibliography . poems written in the leisure hours of a journeyman mason. _inverness._ . letters on the herring fishery. _inverness_ (reprint from _inverness courier_). . scenes and legends of the north of scotland; or, the traditional history of cromarty. _edinburgh._ . letter from one of the scottish people to the right hon. lord brougham and vaux, on the opinions expressed by his lordship on the auchterarder case. _edinburgh._ . the whiggism of the old school as exemplified by the past history and present position of the church of scotland. _edinburgh._ . the old red sandstone; or, new walks in an old field. _edinburgh_ (republished from _witness_). . first impressions of england and its people. _edinburgh._ . footprints of the creator; or, the asterolepis of stromness. _london_, . . the sites bill and the toleration laws; being an examination of the resolutions of the rev. dr. alexander of argyle square chapel congregation. _edinburgh._ . geology of the bass rock (section contributed to m'crie's _history of the bass rock_). _edinburgh._ . thoughts on education. _edinburgh_ (republished from _witness_.) . my schools and schoolmasters; or, the story of my education (_edinburgh_, ). _popular_ edition by w. p. nimmo, hay & mitchell, _edinburgh_, . . the fossiliferous deposits of scotland. _edinburgh_ (address to royal physical society, nov. ). . geology versus astronomy; or, the conditions and the periods; being a view of the modifying effects of geological discovery on the old astronomic inferences respecting the plurality of inhabited worlds. _glasgow._ . the testimony of the rocks; or, geology in its bearing on the two theologies, natural and revealed. _edinburgh_ (twelve lectures before the edinburgh philosophical society, british association, , etc.). . the cruise of the betsey; or, a summer ramble among the fossiliferous deposits of the highlands; with rambles of a geologist, or ten thousand miles over the fossiliferous deposits of scotland. edited by w. s. symonds. _edinburgh._ . sketch book of popular geology. edited by mrs. miller. (lectures delivered before the philosophical institution of edinburgh.) _edinburgh._ . essays. edited by dr. p. bayne (republished from _witness_). . tales and sketches. edited by mrs. miller (contributions to wilson's _border tales_, etc.). . edinburgh and its neighbourhood. edited by mrs. miller. _edinburgh_, . w. p. nimmo, hay & mitchell. . the headship of christ and the rights of the christian people. with preface by dr. p. bayne. _edinburgh_, new edition, nimmo, hay & mitchell. . leading articles. edited by his son-in-law, the rev. john davidson. new edition, _edinburgh_, w. p. nimmo, hay & mitchell. the following list of a uniform edition of hugh miller's works is taken from messrs. w. p. nimmo, hay & mitchell's catalogue:-- my schools and schoolmasters; or, the story of my education. the testimony of the rocks; or, geology in its bearings on the two theologies, natural and revealed. _profusely illustrated._ first impressions of england and its people. sketch-book of popular geology. scenes and legends of the north of scotland; or, the traditional history of cromarty. the old red sandstone; or, new walks in an old field. _profusely illustrated._ the cruise of the betsey; or, a summer ramble among the fossiliferous deposits of the hebrides. with rambles of a geologist; or, ten thousand miles over the fossiliferous deposits of scotland. footprints of the creator; or, the asterolepis of stromness. with preface and notes by mrs. miller, and a biographical sketch by professor agassiz. _profusely illustrated._ tales and sketches. edited, with a preface, by mrs. miller. edinburgh and its neighbourhood, geological and historical. with the geology of the bass rock. essays: historical and biographical, political and social, literary and scientific. leading articles on various subjects. edited by his son-in-law, the rev. john davidson. with a characteristic portrait of the author, facsimile from a photograph, by d. o. hill, r.s.a. the headship of christ and the rights of the christian people. with preface by peter bayne, a.m. _famous scots_ thomas carlyle by hector c. macpherson 'one of the very best little books on carlyle yet written, far outweighing in value some more pretentious works with which we are familiar.'--_literary world._ 'we heartily congratulate author and publishers on the happy commencement of this admirable enterprise.'--_british weekly._ 'as an estimate of the carlylean philosophy and of carlyle's place in literature and his influence in the domains of morals, politics, and social ethics, the volume reveals not only care and fairness, but insight and a large capacity for original thought and judgment.'--_scotsman._ 'lets us get a correct glimpse into the complex workings of a master-mind, and is lighted up by many airy touches of fact and fancy.'--_weekly free press._ 'a fascinating story of a wonderful writer.'--_leeds mercury._ 'an eminently readable book.'--_evening dispatch._ 'is distinctly creditable to the publishers, and worthy of a national series such as they have projected.'--_glasgow daily record._ 'the book is written in an able, masterly, and painstaking manner.'--_educational news._ allan ramsay by oliphant smeaton 'graphic and winning.'--_dundee advertiser._ 'gives many quaint and pleasant glimpses of scottish life in the last century.'--_newcastle chronicle._ 'a most interesting monograph.'--_arbroath herald._ 'discussing ramsay as a pastoral poet and elegist, the biographer gives an able analysis of his chief writings. the whole book is, indeed, marked by authority and ability.'--_banffshire journal._ 'a new and most important addition to our national biography.'--_scottish notes and queries._ 'eminently readable.'--_border advertiser._ 'the story throughout is told with vigour.'--_glasgow citizen._ 'presents a very interesting sketch of the life of the poet, as well as a well-balanced estimate and review of his works.'--_peoples friend._ 'the author has shown scholarship and much enthusiasm in his task.'--_edinburgh dispatch._ 'the kindly, vain, and pompous little wig-maker lives for us in mr. smeaton's pages.'--_daily record._ 'a careful and intelligent study.'--_glasgow herald._ 'a very capable piece of literary craftsmanship by a competent hand.'--_edinburgh evening news._ 'it is not a patchwork picture, but one in which the worker, taking genuine interest in his subject and bestowing conscientious pains on his task, has his materials well in hand, and has used them to produce a portrait that is both lifelike and well-balanced.'--_scotsman._ animals of the past [illustration: phororhacos, a patagonian giant of the miocene. _from a drawing by charles r. knight._] _science for everybody_ animals of the past by frederic a. lucas _curator of the division of comparative anatomy, united states national museum_ fully illustrated new york mcclure, phillips & co. copyright, , by s. s. mcclure co. , by mcclure, phillips & co. published november, . table of contents introductory and explanatory use of scientific names, xvi; estimates of age of earth, xvii; restorations by mr. knight, xviii; works of reference, xix. i. fossils, and how they are formed definition of fossils, ; fossils may be indications of animals or plants, ; casts and impressions, ; why fossils are not more abundant, ; conditions under which fossils are formed, ; enemies of bones, ; dinosaurs engulfed in quicksand, ; formation of fossils, ; petrified bodies frauds, ; natural casts, ; leaves, ; incrustations, ; destruction of fossils, ; references, . ii. the earliest known vertebrates methods of interrogating nature, ; thickness of sedimentary rocks, ; earliest traces of life, ; early vertebrates difficult of preservation, ; armored fishes, ; abundance of early fishes, ; destruction of fish, ; carboniferous sharks, ; known mostly from teeth and spines, ; references, . iii. impressions of the past records of extinct animals, ; earliest traces of animal life, ; formation of tracks, ; tracks in all strata, ; discovery of tracks, ; tracks of dinosaurs, ; species named from tracks, ; footprints aid in determining attitude of animals, ; tracks at carson city, ; references, . iv. rulers of the ancient seas the mosasaurs, ; history of the first known mosasaur, ; jaws of reptiles, ; extinction of mosasaurs, ; the sea-serpent, ; zeuglodon, ; its habits, ; koch's hydrarchus, ; bones collected by mr. schuchert, ; abundance of sharks, ; the great carcharodon, ; arrangement of sharks' teeth, ; references, . v. birds of old earliest birds, ; wings, ; study of young animals, ; the curious hoactzin, ; first intimation of birds, ; archæopteryx, ; birds with teeth, ; cretaceous birds, ; hesperornis, ; loss of power of flight, ; covering of hesperornis, ; attitude of hesperornis, ; curious position of legs, ; toothed birds disappointing, ; early development of birds, ; eggs of early birds, ; references, . vi. the dinosaurs discovery of dinosaur remains, ; nearest relatives of dinosaurs, ; relation of birds to reptiles, ; brain of dinosaurs, ; parallel between dinosaurs and marsupials, ; the great brontosaurus, ; food of dinosaurs, ; habits of diplodocus, ; the strange australian moloch, ; combats of triceratops, ; skeleton of triceratops, ; thespesius and his kin, ; the carnivorous ceratosaurus, ; stegosaurus, the plated lizard, ; preferences, . vii. reading the riddles of the rocks fossils regarded as sports of nature, ; qualifications of a successful collector, ; chances of collecting, ; excavation of fossils, ; strengthening fossils for shipment, ; great size of some specimens, ; the preparation of fossils, ; mistakes of anatomists, ; reconstruction of triceratops, ; distinguishing characters of bones, ; the skeleton a problem in mechanics, ; clothing the bones with flesh, ; the covering of animals, ; outside ornamentation, ; probabilities in the covering of animals, ; impressions of extinct animals, ; mistaken inferences from bones of mammoth, ; coloring of large land animals, ; color markings of young animals, ; references, . viii. feathered giants legend of the moa, ; our knowledge of the moas, ; some moas wingless, ; deposits of moa bones, ; legend of the roc, ; discovery of Æpyornis, ; large-sounding names, ; eggs of great birds, ; the patagonian phororhacos, ; the huge brontornis, ; development of giant birds, ; distribution of flightless birds, ; relation between flightlessness and size, ; references, . ix. the ancestry of the horse north america in the eocene age, ; appearance of early horses, ; early domestication of the horse, ; the toes of horses, ; miocene horses small, ; evidence of genealogy of the horse, ; meaning of abnormalities, ; changes in the climate and animals of the west, ; references, . x. the mammoth the story of the killing of the mammoth, ; derivation of the word "mammoth," ; mistaken ideas as to size of the mammoth, ; size of mammoth and modern elephants, ; finding of an entire mammoth, ; birthplace of the mammoth, ; beliefs concerning its bones, ; the range of the animal, ; theories concerning the extinction of the mammoth, ; man and mammoth, ; origin of the alaskan live mammoth story, ; traits of the innuits, ; an entire mammoth recently found, ; references, . xi. the mastodon differences between mastodon and mammoth, ; affinities of the mastodon, ; vestigial structures, ; distribution of american mastodon, ; first noticed in north america, ; thought to be carnivorous, ; koch's missourium, ; former abundance of mastodons, ; appearance of the animal, ; its size, ; was man contemporary with mastodon? ; the lenape stone, ; legend of the big buffalo, ; references, . xii. why do animals become extinct? extinction sometimes evolution, ; over-specialization as a cause for extinction, ; extinction sometimes unaccountable, ; man's capability for harm small in the past, ; old theories of great convulsions, ; changes in nature slow, ; the case of lingula, ; local extermination, ; the moas and the great auk, ; the case of large animals, ; inter-dependence of living beings, ; coyotes and fruit, ; shaler on the miocene flora of europe, ; man's desire for knowledge, . index, note on the illustrations the original drawings, made especially for this book, are by charles r. knight and james m. gleeson, under the direction of mr. knight. the fact that the originals of these drawings have been presented to and accepted by the united states national museum is evidence of their scientific value. mr. knight has been commissioned by the smithsonian institution, the united states national museum, and the new york museum of natural history, to do their most important pictures of extinct animals. he is the one modern artist who can picture prehistoric animals with artistic charm of presentation as well as with full scientific accuracy. in this instance, the author has personally superintended the artist's work, so that it is as correct in every respect as present knowledge makes possible. of the minor illustrations, some are by mr. bruce horsfall, an artist attached to the staff of the new york museum of natural history, and all have been drawn with the help of and under the author's supervision. list of illustrations fig. page phororhacos, a patagonian giant of the miocene _from a drawing by charles r. knight_ _frontispiece_ . diplomystus, an ancient member of the shad family _from the fish-bed at green river, wyoming. from a specimen in the united states national museum._ . bryozoa, from the shore of the devonian sea that covered eastern new york _from a specimen in yale university museum, prepared by dr. beecher._ . skeleton of a radiolarian very greatly enlarged . cephalaspis and loricaria, an ancient and a modern armored fish . pterichthys, the wing fish . where a dinosaur sat down . footprints of dinosaurs on the brownstone of the connecticut valley _from a slab in the museum of amherst college._ . the track of a three-toed dinosaur . a great sea lizard, _tylosaurus dyspelor from a drawing by j. m. gleeson._ . jaw of a mosasaur, showing the joint that increased the swallowing capacity of that reptile . koch's hydrarchus. composed of portions of the skeletons of several zeuglodons . a tooth of zeuglodon, one of the "yoke teeth," from which it derives the name . archæopteryx, the earliest known bird _from the specimen in the berlin museum._ . nature's four methods of making a wing: bat, pteryodactyl, archæopteryx, and modern bird . young hoactzins . hesperornis, the great toothed diver _from a drawing by j. m. gleeson._ . archæopteryx _as restored by mr. pycraft._ . thespesius, a common herbivorous dinosaur of the cretaceous _from a drawing by charles r. knight._ . a hind leg of the great brontosaurus, the largest of the dinosaurs . a single vertebra of brontosaurus . moloch, a modern lizard that surpasses the stegosaurs in all but size _from a drawing by j. m. gleeson._ . skeleton of triceratops . the horned ceratosaurus, a carnivorous dinosaur _from a drawing by j. m. gleeson._ . stegosaurus, an armored dinosaur of the jurassic _from a drawing by charles r. knight._ . skull of ceratosaurus _from a specimen in the united states national museum._ . triceratops, he of the three-horned face _from a statuette by charles r. knight._ . a hint of buried treasures . relics of the moa . eggs of feathered giants, Æpyornis, ostrich, moa, compared with a hen's egg . skull of phororhacos compared with that of the race-horse lexington . leg of a horse compared with that of the giant moa . the three giants, phororhacos, moa, ostrich . skeleton of the modern horse and of his eocene ancestor . the development of the horse . the mammoth _from a drawing by charles r. knight._ . skeleton of the mammoth in the royal museum of st. petersburg . the mammoth _as engraved by a primitive artist on a piece of mammoth-tusk._ . tooth of mastodon and of mammoth . the missourium of koch _from a tracing of the figure illustrating koch's description._ . the mastodon _from a drawing by j. m. gleeson._ . the lenape stone, reduced _introductory and explanatory_ _at the present time the interest in the ancient life of this earth is greater than ever before, and very considerable sums of money are being expended to dispatch carefully planned expeditions to various parts of the world systematically to gather the fossil remains of the animals of the past. that this interest is not merely confined to a few scientific men, but is shared by the general public, is shown by the numerous articles, including many telegrams, in the columns of the daily papers. the object of this book is to tell some of the interesting facts concerning a few of the better known or more remarkable of these extinct inhabitants of the ancient world; also, if possible, to ease the strain on these venerable animals, caused by stretching them so often beyond their due proportions._ _the book is admittedly somewhat on the lines of mr. hutchinson's "extinct monsters" and "creatures of other days," but it is hoped that it may be considered with books as with boats, a good plan to build after a good model. the information scattered through these pages has been derived from varied sources; some has of necessity been taken from standard books, a part has been gathered in the course of museum work and official correspondence; for much, the author is indebted to his personal friends, and for a part, he is under obligations to friends he has never met, who have kindly responded to his inquiries. the endeavor has been conscientiously made to exclude all misinformation; it is, nevertheless, entirely probable that some mistakes may have crept in, and due apology for these is hereby made beforehand._ _the author expects to be taken to task for the use of scientific names, and the reader may perhaps sympathize with the old lady who said that the discovery of all these strange animals did not surprise her so much as the fact that anyone should know their names when they were found. the real trouble is that there are no common names for these animals. then, too, people who call for easier names do not stop to reflect that, in many cases, the scientific names are no harder than others, simply less familiar, and, when domesticated, they cease to be hard: witness mammoth, elephant, rhinoceros, giraffe, boa constrictor, all of which are scientific names. and if, for example, we were to call the hyracotherium a hyrax beast it would not be a name, but a description, and not a bit more intelligible._ _again, it is impossible to indicate the period at which these creatures lived without using the scientific term for it--jurassic, eocene, pliocene, as the case may be--because there is no other way of doing it._ _some readers will doubtless feel disappointed because they are not told how many years ago these animals lived. the question is often asked--how long ago did this or that animal live? but when the least estimate puts the age of the earth at only , , years, while the longest makes it , , , , it does seem as if it were hardly worth while to name any figures. even when we get well toward the present period we find the time that has elapsed since the beginning of the jurassic, when the dinosaurs held carnival, variously put at from , , to , , years; while from the beginning of the eocene, when the mammals began to gain the supremacy, until now, the figures vary from , , to , , years. so the question of age will be left for the reader to settle to his or her satisfaction._ _the restorations of extinct animals may be considered as giving as accurate representations of these creatures as it is possible to make; they were either drawn by mr. knight, whose name is guarantee that they are of the highest quality, or by mr. gleeson, with the aid of mr. knight's criticism. that they are infallibly correct is out of the question; for, as dr. woodward writes in the preface to "extinct monsters," "restorations are ever liable to emendation, and the present ... will certainly prove no exception to the rule." as a striking instance of this, it was found necessary at the last moment to change the figure of hesperornis, the original life-like portrait proving to be incorrect in attitude, a fact that would have long escaped detection but for the pan-american exposition. the connection between the two is explained on page . however, the reader may rest assured that these restorations are infinitely more nearly correct than many figures of living animals that have appeared within the last twenty-five years, and are even now doing duty._ _the endeavor has been made to indicate, at the end of each chapter, the museums in which the best examples of the animals described may be seen, and also some book or article in which further information may be obtained. as this book is intended for the general reader, references to purely technical articles have, so far as possible, been avoided, and none in foreign languages mentioned._ _for important works of reference on the subject of paleontology, the reader may consult "a manual of paleontology," by alleyne nicholson and r. lydekker, a work in two volumes dealing with invertebrates, vertebrates, and plants, or "a text-book of paleontology," by karl von zittel, english edition, only the first volume of which has so far been published. an admirable book on the vertebrates is "outlines of vertebrate paleontology," by arthur smith woodward. it is to be understood that these are not at all "popular" in their scope, but intended for students who are already well advanced in the study of zoölogy._ animals of the past i fossils, and how they are formed "_how of a thousand snakes each one was changed into a coil of stone._" fossils are the remains, or even the indications, of animals and plants that have, through natural agencies, been buried in the earth and preserved for long periods of time. this may seem a rather meagre definition, but it is a difficult matter to frame one that will be at once brief, exact, and comprehensive; fossils are not necessarily the remains of extinct animals or plants, neither are they, of necessity, objects that have become petrified or turned into stone. bones of the great auk and rytina, which are quite extinct, would hardly be considered as fossils; while the bones of many species of animals, still living, would properly come in that category, having long ago been buried by natural causes and often been changed into stone. and yet it is not essential for a specimen to have had its animal matter replaced by some mineral in order that it may be classed as a fossil, for the siberian mammoths, found entombed in ice, are very properly spoken of as fossils, although the flesh of at least one of these animals was so fresh that it was eaten. likewise the mammoth tusks brought to market are termed fossil-ivory, although differing but little from the tusks of modern elephants. many fossils indeed merit their popular appellation of petrifactions, because they have been changed into stone by the slow removal of the animal or vegetable matter present and its replacement by some mineral, usually silica or some form of lime. but it is necessary to include 'indications of plants or animals' in the above definition because some of the best fossils may be merely impressions of plants or animals and no portion of the objects themselves, and yet, as we shall see, some of our most important information has been gathered from these same imprints. nearly all our knowledge of the plants that flourished in the past is based on the impressions of their leaves left on the soft mud or smooth sand that later on hardened into enduring stone. such, too, are the trails of creeping and crawling things, casts of the burrows of worms and the many footprints of the reptiles, great and small, that crept along the shore or stalked beside the waters of the ancient seas. the creatures themselves have passed away, their massive bones even are lost, but the prints of their feet are as plain to-day as when they were first made. many a crustacean, too, is known solely or mostly by the cast of its shell, the hard parts having completely vanished, and the existence of birds in some formations is revealed merely by the casts of their eggs; and these natural casts must be included in the category of fossils. impressions of vertebrates may, indeed, be almost as good as actual skeletons, as in the case of some fishes, where the fine mud in which they were buried has become changed to a rock, rivalling porcelain in texture; the bones have either dissolved away or shattered into dust at the splitting of the rock, but the imprint of each little fin-ray and every threadlike bone is as clearly defined as it would have been in a freshly prepared skeleton. so fine, indeed, may have been the mud, and so quiet for the time being the waters of the ancient sea or lake, that not only have prints of bones and leaves been found, but those of feathers and of the skin of some reptiles, and even of such soft and delicate objects as jelly fishes. but for these we should have little positive knowledge of the outward appearance of the creatures of the past, and to them we are occasionally indebted for the solution of some moot point in their anatomy. the reader may possibly wonder why it is that fossils are not more abundant; why, of the vast majority of animals that have dwelt upon the earth since it became fit for the habitation of living beings, not a trace remains. this, too, when some objects--the tusks of the mammoth, for example--have been sufficiently well preserved to form staple articles of commerce at the present time, so that the carved handle of my lady's parasol may have formed part of some animal that flourished at the very dawn of the human race, and been gazed upon by her grandfather a thousand times removed. the answer to this query is that, unless the conditions were such as to preserve at least the hard parts of any creature from immediate decay, there was small probability of its becoming fossilized. these conditions are that the objects must be protected from the air, and, practically, the only way that this happens in nature is by having them covered with water, or at least buried in wet ground. [illustration: fig. .--diplomystus, an ancient member of the shad family. from the fishbed at green river, wyoming. _from a specimen in the united states national museum._] if an animal dies on dry land, where its bones lie exposed to the summer's sun and rain and the winter's frost and snow, it does not take these destructive agencies long to reduce the bones to powder; in the rare event of a climate devoid of rain, mere changes of temperature, by producing expansion and contraction, will sooner or later cause a bone to crack and crumble. usually, too, the work of the elements is aided by that of animals and plants. every one has seen a dog make way with a pretty good-sized bone, and the hyena has still greater capabilities in that line; and ever since vertebrate life began there have been carnivorous animals of some kind to play the rôle of bone-destroyers. even were there no carnivores, there were probably then, as now, rats and mice a-plenty, and few suspect the havoc small rodents may play with a bone for the grease it contains, or merely for the sake of exercising their teeth. now and then we come upon a fossil bone, long since turned into stone, on which are the marks of the little cutting teeth of field mice, put there long, long ago, and yet looking as fresh as if made only last week. these little beasts, however, are indirect rather than direct agents in the destruction of bones by gnawing off the outer layers, and thus permitting the more ready entrance of air and water. plants, as a rule, begin their work after an object has become partly or entirely buried in the soil, when the tiny rootlets find their way into fissures, and, expanding as they grow, act like so many little wedges to force it asunder. thus on dry land there is small opportunity for a bone to become a fossil; but, if a creature so perishes that its body is swept into the ocean or one of its estuaries, settles to the muddy bottom of a lake or is caught on the sandy shoals of some river, the chances are good that its bones will be preserved. they are poorest in the ocean, for unless the body drifts far out and settles down in quiet waters, the waves pound the bones to pieces with stones or scour them away with sand, while marine worms may pierce them with burrows, or echinoderms cut holes for their habitations; there are more enemies to a bone than one might imagine. suppose, however, that some animal has sunk in the depths of a quiet lake, where the wash of the waves upon the shore wears the sand or rock into mud so fine that it floats out into still water and settles there as gently as dew upon the grass. little by little the bones are covered by a deposit that fills every groove and pore, preserving the mark of every ridge and furrow; and while this may take long, it is merely a matter of time and favorable circumstance to bury the bones as deeply as one might wish. scarce a reader of these lines but at some time has cast anchor in some quiet pond and pulled it up, thickly covered with sticky mud, whose existence would hardly be suspected from the sparkling waters and pebbly shores. if, instead of a lake, our animal had gone to the bottom of some estuary into which poured a river turbid with mud, the process of entombment would have been still more rapid, while, had the creature been engulfed in quicksand, it would have been the quickest method of all; and just such accidents did take place in the early days of the earth as well as now. at least two examples of the great dinosaur thespesius have been found with the bones all in place, the thigh bones still in their sockets and the ossified tendons running along the backbone as they did in life. this would hardly have happened had not the body been surrounded and supported so that every part was held in place and not crushed, and it is difficult to see any better agency for this than burial in quicksand. if such an event as we have been supposing took place in a part of the globe where the land was gradually sinking--and the crust of the earth is ever rising and falling--the mud and sand would keep on accumulating until an enormously thick layer was formed. the lime or silica contained in the water would tend to cement the particles of mud and grains of sand into a solid mass, while the process would be aided by the pressure of the overlying sediment, the heat created by this pressure, and that derived from the earth beneath. during this process the animal matter of bones or other objects would disappear and its place be taken by lime or silica, and thus would be formed a layer of rock containing fossils. the exact manner in which this replacement is effected and in which the chemical and mechanical changes occur is very far from being definitely known--especially as the process of "fossilization" must at times have been very complicated. in the case of fossil wood greater changes have taken place than in the fossilization of bone, for there is not merely an infiltration of the specimen but a complete replacement of the original vegetable by mineral matter, the interior of the cells being first filled with silica and their walls replaced later on. so completely and minutely may this change occur that under the microscope the very cellular structure of the wood is visible, and as this varies according to the species, it is possible, by microscopical examination, to determine the relationship of trees in cases where nothing but fragments of the trunk remain. the process of fossilization is at best a slow one, and soft substances such as flesh, or even horn, decay too rapidly for it to take place, so that all accounts of petrified bodies, human or otherwise, are either based on deliberate frauds or are the result of a very erroneous misinterpretation of facts. that the impression or cast of a body _might_ be formed in nature, somewhat as casts have been made of those who perished at pompeii, is true; but, so far, no authentic case of the kind has come to light, and the reader is quite justified in disbelieving any report of "a petrified man." natural casts of such hard bodies as shells are common, formed by the dissolving away of the original shell after it had become enclosed in mud, or even after this had changed to stone, and the filling up of this space by the filtering in of water charged with lime or silica, which is there deposited, often in crystalline form. in this way, too, are formed casts of eggs of reptiles and birds, so perfect that it is possible to form a pretty accurate opinion as to the group to which they belong. [illustration: fig. .--bryozoa from the shore of the devonian sea that covered eastern new york. _from a specimen in yale university museum, prepared by dr. beecher._] sometimes it happens that shells or other small objects imbedded in limestone have been dissolved and replaced by silica, and in such cases it is possible to eat away the enveloping rock with acid and leave the silicified casts. by this method specimens of shells, corals, and bryozoans are obtained of almost lace-like delicacy, and as perfect as if only yesterday gathered at the sea-shore. casts of the interior of shells, showing many details of structure, are common, and anyone who has seen clams dug will understand how they are formed by the entrance of mud into the empty shell. casts of the kernels of nuts are formed in much the same way, and professor e. h. barbour has thus described the probable manner in which this was done. when the nuts were dropped into the water of the ancient lake the kernel rotted away, but the shell, being tough and hard, would probably last for years under favorable circumstances. throughout the marls and clays of the bad lands (of south dakota) there is a large amount of potash. this is dissolved by water, and then acts upon quartz, carrying it away in solution. this would find its way by infiltration into the interior of the nut. at the same time with this process, carrying lime carbonate in solution was going on, so that doubtless the stone kernels, consisting of pretty nearly equal parts of lime and silica, were deposited within the nuts. these kernels, of course, became hard and flinty in time, and capable of resisting almost any amount of weathering. not so the organic shell; this eventually would decay away, and so leave the filling or kernel of chalcedony and lime.[ ] [ ] _right here is the weak spot in professor barbour's explanation, and an illustration of our lack of knowledge. for it is difficult to see why the more enduring husk should not have become mineralized equally with the cavity within._ "fossil leaves" are nothing but fine casts, made in natural moulds, and all have seen the first stages in their formation as they watched the leaves sailing to the ground to be covered by mud or sand at the next rain, or dropping into the water, where sooner or later they sink, as we may see them at the bottom of any quiet woodland spring. impressions of leaves are among the early examples of color-printing, for they are frequently of a darker, or even different, tint from that of the surrounding rock, this being caused by the carbonization of vegetable matter or to its action on iron that may have been present in the soil or water. besides complete mineralization, or petrifaction, there are numerous cases of incomplete or semi-fossilization, where modern objects, still retaining their phosphate of lime and some animal matter even, are found buried in rock. this takes place when water containing carbonate of lime, silica, or sometimes iron, flows over beds of sand, cementing the grains into solid but not dense rock, and at the same time penetrating and uniting with it such things as chance to be buried. in this way was formed the "fossil man" of guadeloupe, west indies, a skeleton of a modern carib lying in recent concretionary limestone, together with shells of existing species and fragments of pottery. in a similar way, too, human remains in parts of florida have, through the infiltration of water charged with iron, become partially converted into limonite iron ore; and yet we know that these bones have been buried within quite recent times. sometimes we hear of springs or waters that "turn things into stone," but these tales are quite incorrect. waters there are, like the celebrated hot springs of auvergne, france, containing so much carbonate of lime in solution that it is readily deposited on objects placed therein, coating them more or less thickly, according to the length of time they are allowed to remain. this, however, is merely an encrustation, not extending into the objects. in a similar way the precipitation of solid material from waters of this description forms the porous rock known as tufa, and this often encloses moss, twigs, and other substances that are in no way to be classed with fossils. but some streams, flowing over limestone rocks, take up considerable carbonate of lime, and this may be deposited in water-soaked logs, replacing more or less of the woody tissue and thus really partially changing the wood into stone. the very rocks themselves may consist largely of fossils; chalk, for example, is mainly made up of the disintegrated shells of simple marine animals called foraminifers, and the beautiful flint-like "skeletons" of other small creatures termed radiolarians, minute as they are, have contributed extensively to the formation of some strata. even after an object has become fossilized, it is far from certain that it will remain in good condition until found, while the chance of its being found at all is exceedingly small. when we remember that it is only here and there that nature has made the contents of the rocks accessible by turning the strata on edge, heaving them into cliffs or furrowing them with valleys and canyons, we realize what a vast number of pages of the fossil record must remain not only unread, but unseen. the wonder is, not that we know so little of the history of the past, but that we have learned so much, for not only is nature careless in keeping the records--preserving them mostly in scattered fragments--but after they have been laid away and sealed up in the rocks they are subject to many accidents. some specimens get badly flattened by the weight of subsequently deposited strata, others are cracked and twisted by the movements of the rocks during periods of upheaval or subsidence, and when at last they are brought to the surface, the same sun and rain, snow and frost, from which they once escaped, are ready to renew the attack and crumble even the hard stone to fragments. such, very briefly, are some of the methods by which fossils may be formed, such are some of the accidents by which they may be destroyed; but this description must be taken as a mere outline and as applying mainly to vertebrates, or backboned animals, since it is with them that we shall have to deal. it may, however, show why it is that fossils are not more plentiful, why we have mere hints of the existence of many animals, and why myriads of creatures may have flourished and passed away without so much as leaving a trace of their presence behind. _references_ _a very valuable and interesting article by dr. charles a. white, entitled "the relation of biology to geological investigation," will be found in the report of the united states national museum for . this comprises a series of essays on the nature and scientific uses of fossil remains, their origin, relative chronological value and other questions pertaining to them. the united states national museum has published a pamphlet, part k, bulletin , containing directions for collecting and preparing fossils, by charles schuchert; and another, part b, bulletin , collecting recent and fossil plants, by f. h. knowlton._ [illustration: fig. .--skeleton of a radiolarian very greatly enlarged.] ii the earliest known vertebrates "_we are the ancients of the earth and in the morning of the times._" there is a universal, and perfectly natural, desire for information, which in ourselves we term thirst for knowledge and in others call curiosity, that makes mankind desire to know how everything began and causes much speculation as to how it all will end. this may take the form of a wish to know how a millionaire made his first ten cents, or it may lead to the questions--what is the oldest animal? or, what is the first known member of the great group of backboned animals at whose head man has placed himself? and, what did this, our primeval and many-times-removed ancestor, look like? the question is one that has ever been full of interest for naturalists, and nature has been interrogated in various ways in the hope that she might be persuaded to yield a satisfactory answer. the most direct way has been that of tracing back the history of animal life by means of fossil remains, but beyond a certain point this method cannot go, since, for reasons stated in various places in these pages, the soft bodies of primitive animals are not preserved. to supplement this work, the embryologist has studied the early stages of animals, as their development throws a side-light on their past history. and, finally, there is the study of the varied forms of invertebrates, some of which have proved to be like vertebrates in part of their structure, while others have been revealed as vertebrates in disguise. so far these various methods have yielded various answers, or the replies, like those of the delphic oracle, have been variously interpreted so that vertebrates are considered by some to have descended from the worms, while others have found their beginnings in some animal allied to the king crab. every student of genealogy knows only too well how difficult a matter it is to trace a family pedigree back a few centuries, how soon the family names become changed, the line of descent obscure, and how soon gaps appear whose filling in requires much patient research. how much more difficult must it be, then, to trace the pedigree of a race that extends, not over centuries, but thousands of centuries; how wide must be some of the gaps, how very different may the founders of the family be from their descendants! the words old and ancient that we use so often in speaking of fossils appeal to us somewhat vaguely, for we speak of the ancient civilizations of greece and rome, and call a family old that can show a pedigree running back four or five hundred years, when such as these are but affairs of yesterday compared with even recent fossils. perhaps we may better appreciate the meaning of these words by recalling that, since the dawn of vertebrate life, sufficient of the earth's surface has been worn away and washed into the sea to form, were the strata piled directly one upon the other, fifteen or twenty miles of rock. this, of course, is the sum total of sedimentary rocks, for such a thickness as this is not to be found at any one locality; because, during the various ups and downs that this world of ours has met with, those portions that chanced to be out of water would receive no deposit of mud or sand, and hence bear no corresponding stratum of rock. the reader may think that there is a great deal of difference between fifteen and twenty miles, but this liberal margin is due to the difficulty of measuring the thickness of the rocks, and in europe the sum of the measurable strata is much greater than in north america. the earliest traces of animal life are found deeper still, beneath something like eighteen to twenty-five miles of rock, while below this level are the strata in which dwelt the earliest living things, organisms so small and simple that no trace of their existence has been left, and we infer that they were there because any given group starts in a modest way with small and simple individuals. at the bottom, then, of twenty miles of rocks the seeker for the progenitor of the great family of backboned animals finds the scant remains of fish-like animals that the cautious naturalist, who is much given to "hedging," terms, not vertebrates, but prevertebrates or the forerunners of backboned animals. the earliest of these consist of small bony plates, and traces of a cartilaginous backbone from the lower silurian of colorado, believed to represent relatives of chimæra and species related to those better-known forms holoptychius and osteolepis, which occur in higher strata. there are certainly indications of vertebrate life, but the remains are so imperfect that little more can be said regarding them, and this is also true of the small conical teeth which occur in the lower silurian of st. petersburg, and are thought to be the teeth of some animal like the lamprey. a little higher up in the rocks, though not in the scale of life, in the lower old red sandstone of england, are found more numerous and better preserved specimens of another little fish-like creature, rarely if ever exceeding two inches in length, and also related (probably) to the hag-fishes and lampreys that live to-day. these early vertebrates are not only small, but they were cartilaginous, so that it was essential for their preservation that they should be buried in soft mud as soon as possible after death. even if this took place they were later on submitted to the pressure of some miles of overlying rock until, in some cases, their remains have been pressed out thinner than a sheet of paper, and so thoroughly incorporated into the surrounding stone that it is no easy matter to trace their shadowy outlines. with such drawbacks as these to contend with, it can scarcely be wondered at that, while some naturalists believe these little creatures to be related to the lamprey, others consider that they belong to a perfectly distinct group of animals, and others still think it possible that they may be the larval or early stages of larger and better-developed forms. still higher up we come upon the abundant remains of numerous small fish-like animals, more or less completely clad in bony armor, indicating that they lived in troublous times when there was literally a fight for existence and only such as were well armed or well protected could hope to survive. a parallel case exists to-day in some of the rivers of south america, where the little cat-fishes would possibly be eaten out of existence but for the fact that they are covered--some of them very completely--with plate-armor that enables them to defy their enemies, or renders them such poor eating as not to be worth the taking. the arrangement of the plates or scales in the living loricaria is very suggestive of the series of bony rings covering the body of the ancient cephalaspis, only the latter, so far as we know, had no side-fins; but the creatures are in no wise related, and the similarity is in appearance only. [illustration: fig. .--cephalaspis and loricaria, an ancient and a modern armored fish.] pterichthys, the wing fish, was another small, quaint, armor-clad creature, whose fossilized remains were taken for those of a crab, and once described as belonging to a beetle. certainly the buckler of this fish, which is the part most often preserved, with its jointed, bony arms, looks to the untrained eye far more like some strange crustacean than a fish, and even naturalists have pictured the animal as crawling over the bare sands by means of those same arms. these fishes and their allies were once the dominant type of life, and must have abounded in favored localities, for in places are great deposits of their protective shields jumbled together in a confused mass, and, save that they have hardened into stone, lying just as they were washed up on the ancient beach ages ago. how abundant they were may be gathered from the fact that it is believed their bodies helped consolidate portions of the strata of the english old red sandstone. says mr. hutchinson, speaking of the caithness flagstones, "they owe their peculiar tenacity and durability to the dead fishes that rotted in their midst while yet they were only soft mud. for just as a plaster cast boiled in oil becomes thereby denser and more durable, so the oily and other matter coming from decomposing fish operated on the surrounding sand or mud so as to make it more compact." it may not be easy to explain how it came to pass that fishes dwelling in salt water, as these undoubtedly did, were thus deposited in great numbers, but we may now and then see how deposits of fresh-water fishes may have been formed. when rivers flowing through a stretch of level country are swollen during the spring floods, they overflow their banks, often carrying along large numbers of fishes. as the water subsides these may be caught in shallow pools that soon dry up, leaving the fishes to perish, and every year the illinois game association rescues from the "back waters" quantities of bass that would otherwise be lost. mr. f. s. webster has recorded an instance that came under his observation in texas, where thousands of gar pikes, trapped in a lake formed by an overflow of the rio grande, had been, by the drying up of this lake, penned into a pool about seventy-five feet long by twenty-five feet wide. the fish were literally packed together like sardines, layer upon layer, and a shot fired into the pool would set the entire mass in motion, the larger gars as they dashed about casting the smaller fry into the air, a score at a time. mr. webster estimates that there must have been not less than or fish in the pool, from a foot and a half up to seven feet in length, every one of which perished a little later. in addition to the fish in the pond, hundreds of those that had died previously lay about in every direction, and one can readily imagine what a fish-bed this would have made had the occurrence taken place in the past. from the better-preserved specimens that do now and then turn up, we are able to obtain a very exact idea of the construction of the bony cuirass by which pterichthys and its american cousin were protected, and to make a pretty accurate reconstruction of the entire animal. these primitive fishes had mouths, for eating is a necessity; but these mouths were not associated with true jaws, for the two do not, as might be supposed, necessarily go together. neither did these animals possess hard backbones, and, while pterichthys and its relatives had arms or fins, the hard parts of these were not on the inside but on the outside, so that the limb was more like the leg of a crab than the fin of a fish; and this is among the reasons why some naturalists have been led to conclude that vertebrates may have developed from crustaceans. pteraspis, another of these little armored prevertebrates, had a less complicated covering, and looked very much like a small fish with its fore parts caught in an elongate clam-shell. the fishes that we have so far been considering--orphans of the past they might be termed, as they have no living relatives--were little fellows; but their immediate successors, preserved in the devonian strata, particularly of north america, were the giants of those days, termed, from their size and presumably fierce appearance, titantichthys and dinichthys, and are related to a fish, _ceratodus_, still living in australia. we know practically nothing of the external appearance of these fishes, great and fierce though they may have been, with powerful jaws and armored heads, for they had no bony skeleton--as if they devoted their energies to preying upon their neighbors rather than to internal improvements. they attained a length of ten to eighteen feet, with a gape, in the large species called titanichthys, of four feet, and such a fish might well be capable of devouring anything known to have lived at that early date. succeeding these, in carboniferous times, came a host of shark-like creatures known mainly from their teeth and spines, for their skeletons were of cartilage, and belonging to types that have mostly perished, giving place to others better adapted to the changed conditions wrought by time. almost the only living relative of these early fishes is a little shark, known as the port jackson shark, living in australian waters. like the old sharks, this one has a spine in front of his back fins, and, like them, he fortunately has a mouthful of diversely shaped teeth; fortunately, because through their aid we are enabled to form some idea of the manner in which some of the teeth found scattered through the rocks were arranged. for the teeth were not planted in sockets, as they are in higher animals, but simply rested on the jaws, from which they readily became detached when decomposition set in after death. to complicate matters, the teeth in different parts of the jaws were often so unlike one another that when found separately they would hardly be suspected of having belonged to the same animal. besides teeth these fishes, for purposes of offence and defence, were usually armed with spines, sometimes of considerable size and strength, and often elaborately grooved and sculptured. as the soft parts perished the teeth and spines were left to be scattered by waves and currents, a tooth here, another there, and a spine somewhere else; so it has often happened that, being found separately, two or three quite different names have been given to one and the same animal. now and then some specimen comes to light that escaped the thousand and one accidents to which such things were exposed, and that not only shows the teeth and spines but the faint imprint of the body and fins as well. and from such rare examples we learn just what teeth and spines go with one another, and sometimes find that one fish has received names enough for an entire school. these ancient sharks were not the large and powerful fishes that we have to-day--these came upon the scene later--but mostly fishes of small size, and, as indicated by their spines, fitted quite as much for defence as offence. their rise was rapid, and in their turn they became the masters of the world, spreading in great numbers through the waters that covered the face of the earth; but their supremacy was of short duration, for they declined in numbers even during the carboniferous period, and later dwindled almost to extinction. and while sharks again increased, they never reached their former abundance, and the species that arose were swift, predatory forms, better fitted for the struggle for existence. _references_ _the early fishes make but little show in a museum, both on account of their small size and the conditions under which they have been preserved. the museum of comparative zoölogy has a large collection of these ancient vertebrates, and there is a considerable number of fine teeth and spines of carboniferous sharks in the united states national museum._ _hugh miller's "the old red sandstone" contains some charming descriptions of his discoveries of pterichthys and related forms, and this book will ever remain a classic._ [illustration: fig. .--pterichthys, the wing fish.] iii impressions of the past "_the weird palimpsest, old and vast, wherein thou hid'st the spectral past._" the rev. h. n. hutchinson commences one of his interesting books with emerson's saying, "that everything in nature is engaged in writing its own history;" and, as this remark cannot be improved on, it may well stand at the head of a chapter dealing with the footprints that the creatures of yore left on the sands of the sea-shore, the mud of a long-vanished lake bottom, or the shrunken bed of some water-course. not only have creatures that walked left a record of their progress, but the worms that burrowed in the sand, the shell-fish that trailed over the mud when the tide was low, the stranded crab as he scuttled back to the sea--each and all left some mark to tell of their former presence. even the rain that fell and the very wind that blew sometimes recorded the direction whence they came, and we may read in the rocks, also, accounts of freshets sweeping down with turbid waters, and of long periods of drouth, when the land was parched and lakes and rivers shrank beneath the burning sun. all these things have been told and retold; but, as there are many who have not read mr. hutchinson's books and to whom buckland is quite unknown, it may be excusable to add something to what has already been said in the first chapter of these impressions of the past. the very earliest suggestion we have of the presence of animal life upon this globe is in the form of certain long dark streaks below the cambrian of england, considered to be traces of the burrows of worms that were filled with fine mud, and while this interpretation may be wrong there is, on the other hand, no reason why it may not be correct. plant and animal life must have had very lowly beginnings, and it is not at all probable that we shall find any trace of the simple and minute forms with which they started,[ ] though we should not be surprised at finding hints of the presence of living creatures below the strata in which their remains are actually known to occur. [ ] _within the last few years what are believed to be indications of bacteria have been described from carboniferous rocks. naturally such announcements must be accepted with great caution, for while there is no reason why this may not be true, it is much more probable that definite evidence of the effects of bacteria on plants should be found than that these simple, single-celled organisms should themselves have been detected._ worm burrows, to be sure, are hardly footprints, but tracks are found in cambrian rocks just above the strata in which the supposed burrows occur, and from that time onward there are tracks a-plenty, for they have been made, wherever the conditions were favorable, ever since animals began to walk. all that was needed was a medium in which impressions could be made and so filled that there was imperfect adhesion between mould and matrix. thus we find them formed not only by the sea-shore, in sands alternately dry and covered, but by the river-side, in shallow water, or even on land where tracks might be left in soft or moist earth into which wind-driven dust or sand might lodge, or sand or mud be swept by the mimic flood caused by a thunder shower. so there are tracks in strata of every age; at first those of invertebrates: after the worm burrows the curious complicated trails of animals believed to be akin to the king crab; broad, ribbed, ribbon-like paths ascribed to trilobites; then faint scratches of insects, and the shallow, palmed prints of salamanders, and the occasional slender sprawl of a lizard; then footprints, big and little, of the horde of dinosaurs and, finally, miles above the cambrian, marks of mammals. sometimes, like the tracks of salamanders and reptiles in the carboniferous rocks of pennsylvania and kansas, these are all we have to tell of the existence of air-breathing animals. again, as with the iguanodon, the foot to fit the track may be found in the same layer of rock, but this is not often the case. although footprints in the rocks must often have been seen, they seem to have attracted little or no notice from scientific men until about to , when they were almost simultaneously described both in europe and america; even then, it was some time before they were generally conceded to be actually the tracks of animals, but, like worm burrows and trails, were looked upon as the impressions of sea-weeds. the now famous tracks in the "brown stone" of the connecticut valley seem to have first been seen by pliny moody in , when he ploughed up a specimen on his farm, showing small imprints, which later on were popularly called the tracks of noah's raven. the discovery passed without remark until in the footprints came under the observation of dr. james deane, who, in turn, called professor hitchcock's attention to them. the latter at once began a systematic study of these impressions, publishing his first account in and continuing his researches for many years, in the course of which he brought together the fine collection in amherst college. at that time dinosaurs were practically unknown, and it is not to be wondered at that these three-toed tracks, great and small, were almost universally believed to be those of birds. so it is greatly to the credit of dr. deane, who also studied these footprints, that he was led to suspect that they might have been made by other animals. this suspicion was partly caused by the occasional association of four and five-toed prints with the three-toed impressions, and partly by the rare occurrence of imprints showing the texture of the sole of the foot, which was quite different from that of any known bird. [illustration: fig. .--where a dinosaur sat down.] in the light of our present knowledge we are able to read many things in these tracks that were formerly more or less obscure, and to see in them a complete verification of dr. deane's suspicion that they were not made by birds. we see clearly that the long tracks called _anomoepus_, with their accompanying short fore feet, mark where some dinosaur squatted down to rest or progressed slowly on all-fours, as does the kangaroo when feeding quietly;[ ] and we interpret the curious heart-shaped depression sometimes seen back of the feet, not as the mark of a stubby tail, but as made by the ends of the slender pubes, bones that help form the hip-joints. then, too, the mark of the inner, or short first, toe, is often very evident, although it was a long time before the bones of this toe were actually found, and many of the dinosaurs now known to have four toes were supposed to have but three. [ ] _it is to be noted that a leaping kangaroo touches the ground neither with his heel nor his tail, but that between jumps he rests momentarily on his toes only; hence impressions made by any creature that jumped like a kangaroo would be very short._ it seems strange, and it is strange, that while so many hundreds of tracks should have been found in the limited area exposed to view, so few bones have been found--our knowledge of the veritable animals that made the tracks being a blank. a few examples have, it is true, been found, but these are only a tithe of those known to have existed; while of the great animals that strode along the shore, leaving tracks fifteen inches long and a yard apart pressed deeply into the hard sand, not a bone remains. the probability is that the strata containing their bones lie out to sea, whither their bodies were carried by tides and currents, and that we may never see more than the few fragments that were scattered along the seaside. that part of the valley of the connecticut wherein the footprints are found seems to have been a long, narrow estuary running southward from turner's falls, mass., where the tracks are most abundant and most clear. the topography was such that this estuary was subject to sudden and great fluctuations of the water-level, large tracts of shore being now left dry to bake in the sun, and again covered by turbid water which deposited on the bottom a layer of mud. over and over again this happened, forming layer upon layer of what is now stone, sometimes the lapse of time between the deposits being so short that the tracks of the big dinosaurs extend through several sheets of stone; while again there was a period of drouth when the shore became so dry and firm as to retain but a single shallow impression. [illustration: fig. .--footprints of dinosaurs on the brownstone of the connecticut valley. _from a slab in the museum of amherst college._] something of the wealth of animal life that roamed about this estuary may be gathered from the number of different footprints recorded on the sands, and these are so many and so varied that professor hitchcock in two extensive reports enumerated over species, representing various groups of animals. one little point must, however, be borne in mind, that mere size is no sure indication of differences in dealing with reptiles, for these long-lived creatures grow almost continuously throughout life, so that one animal even may have left his footprints over and over in assorted sizes from one end of the valley to the other. the slab shown in fig. is a remarkably fine example of these connecticut river footprints; it shows in relief forty-eight tracks of the animal called brontozoum sillimanium and six of a lesser species. it was quarried near middletown, in , and for sixty years did duty as a flagstone, fortunately with the face downwards. when taken up for repairs the tracks were discovered, and later on the slab, which measures three by five feet, was transferred to the museum of amherst college. there is an interesting parallel between the history of footprints in england and america, for they were noticed at about the same time, , in both countries; in each case the tracks were in rocks of triassic age, and, in both instances, the animals that made them have never been found. in england, however, the tracks first found were those ascribed to tortoises, though a little later dinosaur footprints were discovered in the same locality. oddly enough these numerous tracks all run one way, from west to east, as if the animals were migrating, or were pursuing some well-known and customary route to their feeding grounds. for some reason triassic rocks are particularly rich in footprints; for from strata of this same age in the rhine valley come those curious examples so like the mark of a stubby hand that dr. kaup christened the beast supposed to have made them _cheirotherium_, beast with a hand, suggesting that they had been made by some gigantic opossum. as the tracks measure five by eight inches, it would have been rather a large specimen, but the mammals had not then arisen, and it is generally believed that the impressions were made by huge (for their kind) salamander-like creatures, known as labyrinthodonts, whose remains are found in the same strata. footprints may aid greatly in determining the attitude assumed by extinct animals, and in this way they have been of great service in furnishing proof that many of the dinosaurs walked erect. the impressions on the sands of the old connecticut estuary may be said to show this very plainly, but in england and belgium is evidence still more conclusive, in the shape of tracks ascribed to the iguanodon. these were made on soft soil into which the feet sank much more deeply than in the connecticut sands, and the casts made in the natural moulds show the impression of toes very clearly. if the animals had walked flat-footed, as we do, the prints of the toes would have been followed by a long heel mark, but such is not the case; there are the sharply defined marks of the toes and nothing more, showing plainly that the iguanodons walked, like birds, on the toes alone. more than this, had these dinosaurs dragged their tails there would have been a continuous furrow between the footprints; but nothing of this sort is to be found; on the contrary, a fine series of tracks, uncovered at hastings, england, made by several individuals and running for seventy-five feet, shows footprints only. hence it may be fairly concluded that these great creatures carried their tails clear of the ground, as shown in the picture of _thespesius_, the weight of the tail counterbalancing that of the body. where crocodilians or some of the short-limbed dinosaurs have crept along there is, as we should expect, a continuous furrow between the imprints of the feet. this is what footprints tell us when their message is read aright; when improperly translated they only add to the enormous bulk of our ignorance. some years ago we were treated to accounts of wonderful footprints in the rock of the prison-yard at carson city, nev., which, according to the papers, not only showed that men existed at a much earlier period than the scientific supposed, but that they were men of giant stature. this was clearly demonstrated by the footprints, for they were such as _might_ have been made by huge moccasined feet, and this was all that was necessary for the conclusion that they _were_ made by just such feet. for it is a curious fact that the majority of mankind seem to prefer any explanation other than the most simple and natural, particularly in the case of fossils, and are always looking for a primitive race of gigantic men. bones of the mastodon and mammoth have again and again been eagerly accepted as those of giants; a salamander was brought forward as evidence of the deluge (_homo diluvii testis_); ammonites and their allies pose as fossil snakes, and the "petrified man" flourishes perennially. however, in this case the prints were recognized by naturalists as having most probably been made by some great ground sloth, such as the mylodon or morotherium, these animals, though belonging to a group whose headquarters were in patagonia, having extended their range as far north as oregon. that the tracks seemed to have been made by a biped, rather than a quadruped, was due to the fact that the prints of the hind feet fell upon and obliterated the marks of the fore. still, a little observation showed that here and there prints of the fore feet were to be seen, and on one spot were indications of a struggle between two of the big beasts. the mud, or rather the stone that had been mud, bears the imprints of opposing feet, one set deeper at the toes, the other at the heels, as if one animal had pushed and the other resisted. in the rock, too, are broad depressions bearing the marks of coarse hair, where one creature had apparently sat on its haunches in order to use its fore limbs to the best advantage. other footprints there are in this prison-yard; the great round "spoor" of the mammoth, the hoofs of a deer, and the paws of a wolf(?), indicating that hereabout was some pool where all these creatures came to drink. more than this, we learn that when these prints were made, or shortly after, a strong wind blew from the southeast, for on that face of the ridges bounding the margin of each big footprint, we find sand that lodged against the squeezed-up mud and stuck there to serve as a perpetual record of the direction of the wind. _references_ _almost every museum has some specimen of the connecticut valley footprints, but the largest and finest collections are in the museums of amherst college, mass., and yale university, although, owing to lack of room, only a few of the yale specimens are on exhibition. the collection at amherst comprises most of the types described by professor e. hitchcock in his "ichnology of new england," a work in two fully illustrated quarto volumes. other footprints are described and figured by dr. j. deane in "ichnographs from the sandstone of the connecticut river."_ [illustration: fig. .--the track of a three-toed dinosaur.] iv rulers of the ancient seas "_a time there was when the universe was darkness and water, wherein certain animals of frightful and compound mien were generated. there were serpents, and other creatures with the mixed shapes of one another...._"--_the archaic genesis._ history shows us how in the past nation after nation has arisen, increased in size and strength, extended its bounds and dominion until it became the ruling power of the world, and then passed out of existence, often so completely that nothing has remained save a few mounds of dirt marking the graves of former cities. and so has it been with the kingdoms of nature. just as greece, carthage, and rome were successively the rulers of the sea in the days that we call old, so, long before the advent of man, the seas were ruled by successive races of creatures whose bones now lie scattered over the beds of the ancient seas, even as the wrecks of galleys lie strewn over the bed of the mediterranean. for a time the armor-clad fishes held undisputed sway; then their reign was ended by the coming of the sharks, who in their turn gave way to the fish-lizards, the ichthyosaurs and plesiosaurs. these, however, were rather local in their rule; but the next group of reptiles to appear on the scene, the great marine reptiles called mosasaurs, practically extended their empire around the world, from new zealand to north america. we properly call these reptiles great, for so they were; but there are degrees of greatness, and there is a universal tendency to think of the animals that have become extinct as much greater than those of the present day, to magnify the reptile that we never saw as well as the fish that "got away," and it may be safely said that the greatest of animals will shrink before a two-foot rule. as a matter of fact, no animals are known to have existed that were larger than the whales; and, while there are now no reptiles that can compare in bulk with the dinosaurs, there were few mosasaurs that exceeded in size a first-class crocodile. an occasional mosasaur reaches a length of forty feet, but such are rare indeed, and one even twenty-five feet long is a large specimen,[ ] while the great mugger, or man-eating crocodile, grows, if permitted, to a length of twenty-five or even thirty feet, and need not be ashamed to match his bulk and jaws against those of most mosasaurs. [ ] _it is surprising to find professor cope placing the length of the mosasaurs at , , or feet, as there is not the slightest basis for even the lowest of these figures. professor williston, the best authority on the subject, states, in his volume on the "cretaceous reptiles of kansas," that there is not in existence any specimen of a mosasaur indicating a greater length than feet._ the first of these sea-reptiles to be discovered has passed into history, and now reposes in the jardin des plantes, paris, after changing hands two or three times, the original owner being dispossessed of his treasure by the subtleties of law, while the next holder was deprived of the specimen by main force. thus the story is told by m. faujas st. fond, as rendered into english, in mantell's "petrifactions and their teachings": "some workmen, in blasting the rock in one of the caverns of the interior of the mountain, perceived, to their astonishment, the jaws of a large animal attached to the roof of the chasm. the discovery was immediately made known to m. hoffman, who repaired to the spot, and for weeks presided over the arduous task of separating the mass of stone containing these remains from the surrounding rock. his labors were rewarded by the successful extrication of the specimen, which he conveyed in triumph to his house. this extraordinary discovery, however, soon became the subject of general conversation, and excited so much interest that the canon of the cathedral which stands on the mountain resolved to claim the fossil, in right of being lord of the manor, and succeeded, after a long and harassing lawsuit, in obtaining the precious relic. it remained for years in his possession, and hoffman died without regaining his treasure. at length the french revolution broke out, and the armies of the republic advanced to the gates of maestricht. the town was bombarded; but, at the suggestion of the committee of savans who accompanied the french troops to select their share of the plunder, the artillery was not suffered to play on that part of the city in which the celebrated fossil was known to be preserved. in the meantime, the canon of st. peter's, shrewdly suspecting the reason why such peculiar favor was shown to his residence, removed the specimen and concealed it in a vault; but, when the city was taken, the french authorities compelled him to give up his ill-gotten prize, which was immediately transmitted to the jardin des plantes, at paris, where it still forms one of the most interesting objects in that magnificent collection." and there it remains to this day. [illustration: fig. .--a great sea lizard, _tylosaurus dyspelor_. _from a drawing by j. m. gleeson._] the seas that rolled over western kansas were the headquarters of the mosasaurs, and hundreds--aye, thousands--of specimens have been taken from the chalk bluffs of that region, some of them in such a fine state of preservation that we are not only well acquainted with their internal structure, but with their outward appearance as well. they were essentially swimming lizards--great, overgrown, and distant relatives of the monitors of africa and asia, especially adapted to a roving, predatory life by their powerful tails and paddle-shaped feet. their cup-and-ball vertebræ indicate great flexibility of the body, their sharp teeth denote ability to capture slippery prey, and the structure of the lower jaw shows that they probably ate in a hurry and swallowed their food entire, or bolted it in great chunks. the jaws of all reptiles are made up of a number of pieces, but these are usually so spliced together that each half of the jaw is one inflexible, or nearly inflexible, mass of bone. in snakes, which swallow their prey entire, the difficulty of swallowing animals greater in diameter than themselves is surmounted by having the two halves of the lower jaw loosely joined at the free ends, so that these may spread wide apart and thus increase the gape of the mouth. this is also helped by the manner in which the jaw is joined to the head. the pelican solves the problem by the length of his mandibles, this allowing so much spring that when open they bow apart to form a nice little landing net. in the mosasaurs, as in the cormorants, among birds, there is a sort of joint in each half of the lower jaw which permits it to bow outward when opened, and this, aided by the articulation of the jaw with the cranium, adds greatly to the swallowing capacity. thus in nature the same end is attained by very different methods. to borrow a suggestion from professor cope, if the reader will extend his arms at full length, the palms touching, and then bend his elbows outward he will get a very good idea of the action of a mosasaur's jaw. the western sea was a lively place in the day of the great mosasaurs, for with them swam the king of turtles, archelon, as mr. wieland has fitly named him, a creature a dozen feet or more in length, with a head a full yard long, while in the shallows prowled great fishes with massive jaws and teeth like spikes. [illustration: fig. .--jaw of a mosasaur, showing the joint that increased the swallowing capacity of that reptile.] there, too, was the great, toothed diver, hesperornis (see page ), while over the waters flew pterodactyls, with a spread of wing of twenty feet, largest of all flying creatures; and, not improbably--nay, very probably--fish-eaters, too; and when each and all of these were seeking their dinners, there were troublous times for the small fry in that old kansan sea. and then there came a change; to the south, to the west, to the north, the land was imperceptibly but surely rising, perhaps only an inch or two in a century, but still rising, until "the ocean in which flourished this abundant and vigorous life was at last completely inclosed on the west by elevations of sea-bottom, so that it only communicated with the atlantic and pacific at the gulf of mexico and the arctic sea." the continued elevation of both eastern and western shores contracted its area, and when ridges of the sea-bottom reached the surface, forming long, low bars, parts of the water-area were included, and connection with salt-water prevented. thus were the living beings imprisoned and subjected to many new risks to life. the stronger could more readily capture the weaker, while the fishes would gradually perish through the constant freshening of the water. with the death of any considerable class, the balance of food-supply would be lost, and many large species would disappear from the scene. the most omnivorous and enduring would longest resist the approach of starvation, but would finally yield to inexorable fate--the last one caught by the shifting bottom among shallow pools, from which his exhausted energies could not extricate him.[ ] [ ] _cope: "the vertebrata of the cretaceous formations of the west," p. , being the "report of the united states geological survey of the territories," vol. ii._ like the "fossil man" the sea-serpent flourishes perennially in the newspapers and, despite the fact that he is now mainly regarded as a joke, there have been many attempts to habilitate this mythical monster and place him on a foundation of firm fact. the most earnest of these was that of m. oudemans, who expressed his belief in the existence of some rare and huge seal-like creature whose occasional appearance in southern waters gave rise to the best authenticated reports of the sea-serpent. among other possibilities it has been suggested that some animal believed to be extinct had really lived over to the present day. now there are a few waifs, spared from the wrecks of ancient faunas, stranded on the shores of the present, such as the australian ceratodus and the gar pikes of north america, and these and all other creatures that could be mustered in were used as proofs to sustain this theory. if, it was said, these animals have been spared, why not others? if a fish of such ancient lineage as the gar pike is so common as to be a nuisance, why may there not be a few plesiosaurs or a mosasaur somewhere in the depths of the ocean? the argument was a good one, the more that we may "suppose" almost anything, but it must be said that no trace of any of these creatures has so far been found outside of the strata in which they have long been known to occur, and all the probabilities are opposed to this theory. still, if some of these creatures _had_ been spared, they might well have passed for sea-serpents, even though zeuglodon, the one most like a serpent in form, was the one most remotely related to snakes. zeuglodon, the yoke-tooth, so named from the shape of its great cutting teeth, was indeed a strange animal, and if we wonder at the greenland whale, whose head is one-third its total length, we may equally wonder at zeuglodon, with four feet of head, ten feet of body, and forty feet of tail. no one, seeing the bones of the trunk and tail for the first time, would suspect that they belonged to the same animal, for while the vertebræ of the body are of moderate size, those of the tail are, for the bulk of creature, the longest known, measuring from fifteen to eighteen inches in length, and weighing in a fossil condition fifty to sixty pounds. in life, the animal was from fifty to seventy feet in length, and not more than six or eight feet through the deepest part of the body, while the tail was much less; the head was small and pointed, the jaws well armed with grasping and cutting teeth, and just back of the head was a pair of short paddles, not unlike those of a fur seal. it is curious to speculate on the habits of a creature in which the tail so obviously wagged the dog and whose articulations all point to great freedom of movement up and down. this may mean that it was an active diver, descending to great depths to prey upon squid, as the sperm-whale does to-day, while it seems quite certain that it must have reared at least a third of its great length out of water to take a comprehensive view of its surroundings. and if size is any indication of power, the great tail, which obviously ended in flukes like those of a whale, must have been capable of propelling the beast at a speed of twenty or thirty miles an hour. something of the kind must have been needed in order that the small head might provide food enough for the great tail, and it has been suggested that inability to do this was the reason why zeuglodon became extinct. on the other hand, it has been ingeniously argued that the huge tail served to store up fat when food was plenty, which was drawn upon when food became scarce. the fur seals do something similar to this, for the males come on shore in may rolling in blubber, and depart in september lean and hungry after a three months' fast. zeuglodons must have been very numerous in the old gulf of mexico, for bones are found abundantly through portions of our southern states; it was also an inhabitant of the old seas of southern europe, but, as we shall see, it gave place to the great fossil shark, and this in turn passed out of existence. still, common though its bones may be, stories of their use for making stone walls--and these stories are still in circulation--resolve themselves on close scrutiny into the occasional use of a big vertebra to support the corner of a corn-crib. the scientific name of zeuglodon is _basilosaurus cetoides_, the whale-like king lizard--the first of these names, _basilosaurus_, having been given to it by the original describer, dr. harlan, who supposed the animal to have been a reptile. now it is a primary rule of nomenclature that the first name given to an animal must stick and may not be changed, even by the act of a zoölogical congress, so zeuglodon must, so far as its name is concerned, masquerade as a reptile for the rest of its paleontological life. this, however, really matters very little, because scientific names are simply verbal handles by which we may grasp animals to describe them, and dr. le conte, to show how little there may be in a name, called a beetle gyascutus. owen's name of zeuglodon, although not tenable as a scientific name, is too good to be wasted, and being readily remembered and easily pronounced may be used as a popular name. [illustration: fig. .--koch's hydrarchus, composed of portions of the skeleton of several zeuglodons.] one might think that a creature sixty or seventy feet long was amply long enough, but dr. albert koch thought otherwise, and did with zeuglodon as, later on, he did with the mastodon, combining the vertebræ of several individuals until he had a monster feet long! this he exhibited in europe under the name of hydrarchus, or water king, finally disposing of the composite creature to the museum of dresden, where it was promptly reduced to its proper dimensions. the natural make-up of zeuglodon is sufficiently composite without any aid from man, for the head and paddles are not unlike those of a seal, the ribs are like those of a manatee, and the shoulder blades are precisely like those of a whale, while the vertebræ are different from those of any other animal, even its own cousin and lesser contemporary dorudon. there were also tiny hind legs tucked away beneath skin, but these, as well as many other parts of the animal's structure were unknown, until mr. charles schuchert collected a series of specimens for the national museum, from which it was possible to restore the entire skeleton. owing to a rather curious circumstance the first attempt at a restoration was at fault; among the bones originally obtained by mr. schuchert there were none from the last half of the tail, an old gully having cut off the hinder portion of the backbone and destroyed the vertebræ. not far away, however, was a big lump of stone containing several vertebræ of just the right size, and these were used as models to complete the papier-maché skeleton shown at atlanta, in . but a year after mr. schuchert collected a series of vertebræ, beginning with the tip of the tail, and these showed conclusively that the first lot of tail vertebræ belonged to a creature still undescribed and one probably more like a whale than zeuglodon himself, whose exact relationships are a little uncertain, as may be imagined from what was said of its structure. mixed with the bones of zeuglodon was the shell of a turtle, nearly three feet long, and part of the backbone of a great water-snake that must have been twenty-five feet long, both previously quite unknown. one more curious thing about zeuglodon bones remains to be told, and then we are done with him; ordinarily a fossil bone will break indifferently in any direction, but the bones of zeuglodon are built, like an onion, of concentric layers, and these have a great tendency to peel off during the preparation of a specimen. * * * * * and now, as the wheels of time and change rolled slowly on, sharks again came uppermost, and the warmer eocene and miocene oceans appear to have fairly teemed with these sea wolves. there were small sharks with slender teeth for catching little fishes, there were larger sharks with saw-like teeth for cutting slices out of larger fishes, and there were sharks that might almost have swallowed the biggest fish of to-day whole, sharks of a size the waters had never before contained, and fortunately do not contain now. we know these monsters mostly by their teeth, for their skeletons were cartilaginous, and this absence of their remains is probably the reason why these creatures are passed by while the adjectives huge, immense, enormous are lavished on the mosasaurs and plesiosaurs--animals that the great-toothed shark, _carcharodon megalodon_, might well have eaten at a meal. for the gaping jaws of one of these sharks, with its hundreds of gleaming teeth must, at a moderate estimate, have measured not less than six feet across. the great white shark, the man-eater, so often found in story books, so rarely met with in real life, attains a length of thirty feet, and a man just makes him a good, satisfactory lunch. now a tooth of this shark is an inch and a quarter long, while a tooth of the huge _megalodon_ is commonly three, often four, and not infrequently five inches long. applying the rule of three to such a tooth as this would give a shark feet long, bigger than most whales, to whom a man would be but a mouthful, just enough to whet his sharkship's appetite. even granting that the rule of three unduly magnifies the dimensions of the brute, and making an ample reduction, there would still remain a fish between seventy-five and one hundred feet long, quite large enough to satisfy the most ambitious of _tuna_ fishers, and to have made bathing in the miocene ocean unpopular. contemporary with the great-toothed shark was another and closely related species that originated with him in eocene times, and these two may possibly have had something to do with the extinction of zeuglodon. this species is distinguished by having on either side of the base of the great triangular cutting teeth a little projection or cusp, like the "ear" on a jar, so that this species has been named _auriculatus_, or eared. the edges of the teeth are also more saw-like than in those of its greater relative, and as the species must have attained a length of fifty or sixty feet it may, with its better armature, have been quite as formidable. and, as perhaps the readers of these pages may know, the supply of teeth never ran short. back of each tooth, one behind another arranged in serried ranks, lay a reserve of six or seven smaller, but growing teeth, and whenever a tooth of the front row was lost, the tooth immediately behind it took its place, and like a well-trained soldier kept the front line unbroken. thus the teeth of sharks are continually developing at the back, and all the teeth are steadily pushing forward, a very simple mechanical arrangement causing the teeth to lie flat until they reach the front of the jaw and come into use. once fairly started in life, these huge sharks spread themselves throughout the warm seas of the world, for there was none might stand before them and say nay. they swarmed along our southern coast, from maryland to texas; they swarmed everywhere that the water was sufficiently warm, for their teeth occur in tertiary strata in many parts of the world, and the deep-sea dredges of the challenger and albatross have brought up their teeth by scores. and then--they perished, perished as utterly as did the hosts of sennacherib. why? we do not know. did they devour everything large enough to be eaten throughout their habitat, and then fall to eating one another? again, we do not know. but perish they did, while the smaller white shark, which came into being at the same time, still lives, as if to emphasize the fact that it is best not to overdo things, and that in the long run the victory is not _always_ to the largest. _references_ _the finest mosasaur skeleton ever discovered, an almost complete skeleton of tylosaurus dyspelor, feet in length, may be seen at the head of the staircase leading to the hall of paleontology, in the american museum of natural history, new york. another good specimen may be seen in the yale university museum, which probably has the largest collection of mosasaurs in existence. another fine collection is in the museum of the state university of kansas, at lawrence._ _the best zeuglodon, the first to show the vestigial hind legs and to make clear other portions of the structure, is in the united states national museum._ _the great sharks are known in this country by their teeth only, and, as these are common in the phosphate beds, specimens may be seen in almost any collection. in the united states national museum, the jaws of a twelve-foot blue shark are shown for comparison. the largest tooth in that collection is - / inches high and inches across the base. it takes five teeth of the blue shark to fill the same number of inches._ _the mosasaurs are described in detail by professor s. w. williston, in vol. iv. of the "university geological survey of kansas." there is a technical--and, consequently, uninteresting--account of zeuglodon in vol. xxiii. of the "proceedings of the united states national museum," page ._ [illustration: fig. .--a tooth of zeuglodon, one of the "yoke teeth," from which it derives the name.] v birds of old "_with head, hands, wings, or feet, pursues his way, and swims, or sinks, or wades, or creeps, or flies._" when we come to discuss the topic of the earliest bird--not the one in the proverb--our choice of subjects is indeed limited, being restricted to the famous and oft-described archæopteryx from the quarries of solenhofen, which at present forms the starting-point in the history of the feathered race. bird-like, or at least feathered, creatures, must have existed before this, as it is improbable that feathers and flight were acquired at one bound, and this lends probability to the view that at least some of the tracks in the connecticut valley are really the footprints of birds. not birds as we now know them, but still creatures wearing feathers, these being the distinctive badge and livery of the order. for we may well speak of the feathered race, the exclusive prerogative of the bird being not flight but feathers; no bird is without them, no other creature wears them, so that birds may be exactly defined in two words, feathered animals. reptiles, and even mammals, may go quite naked or cover themselves with a defensive armor of bony plates or horny scales; but under the blaze of the tropical sun or in the chill waters of arctic seas birds wear feathers only, although in the penguins the feathers have become so changed that their identity is almost lost. [illustration: fig. .--archæopteryx, the earliest known bird. _from the specimen in the berlin museum._] so far as flight goes, there is one entire order of mammals, whose members, the bats, are quite as much at home in the air as the birds themselves, and in bygone days the empire of the air belonged to the pterodactyls; even frogs and fishes have tried to fly, and some of the latter have nearly succeeded in the attempt. as for wings, it may be said that they are made on very different patterns in such animals as the pterodactyl, bat, and bird, and that while the end to be achieved is the same, it is reached by very different methods. the wing membrane of a bat is spread between his out-stretched fingers, the thumb alone being left free, while in the pterodactyl the thumb is wanting and the membrane supported only by what in us is the little finger, a term that is a decided misnomer in the case of the pterodactyl. in birds the fingers have lost their individuality, and are modified for the attachment or support of the wing feathers, but in archæopteryx the hand had not reached this stage, for the fingers were partly free and tipped with claws. [illustration: fig. .--nature's four methods of making a wing. bat, pterodactyl, archæopteryx, and modern bird.] we get some side lights on the structure of primitive birds by studying the young and the earlier stages of living species, for in a very general way it may be said that the development of the individual is a sort of rough sketch or hasty outline of the development of the class of which it is a member; thus the transitory stages through which the chick passes before hatching give us some idea of the structure of the adult birds or bird-like creatures of long ago. now, in embryonic birds the wing ends in a sort of paw and the fingers are separate, quite different from what they become a little later on, and not unlike their condition in archæopteryx, and even more like what is found in the wing of an ostrich. then, too, there are a few birds still left, such as the ostrich, that have not kept pace with the others, and are a trifle more like reptiles than the vast majority of their relatives, and these help a little in explaining the structure of early birds. among these is a queer bird with a queer name, hoactzin, found in south america, which when young uses its little wings much like legs, just as we may suppose was done by birds of old, to climb about the branches. mr. quelch, who has studied these curious birds in their native wilds of british guiana, tells us that soon after hatching, the nestlings begin to crawl about by means of their legs and wings, the well-developed claws on the thumb and finger being constantly in use for hooking to surrounding objects. if they are drawn from the nest by means of their legs, they hold on firmly to the twigs, both with their bill and wings; and if the nest be upset they hold on to all objects with which they come in contact by bill, feet, and wings, making considerable use of the bill, with the help of the clawed wings, to raise themselves to a higher level. [illustration: fig. .--young hoactzins.] thus, by putting these various facts together we obtain some pretty good ideas regarding the appearance and habits of the first birds. the immediate ancestors of birds, their exact point of departure from other vertebrates, is yet to be discovered; at one time it was considered that they were the direct descendants of dinosaurs, or that at least both were derived from the same parent forms, and while that view was almost abandoned, it is again being brought forward with much to support it. it has also been thought that birds and those flying reptiles, the pterodactyls, have had a common ancestry, and the possibility of this is still entertained. be that as it may, it is safe to consider that back in the past, earlier than the jurassic, were creatures neither bird nor reptile, but possessing rudimentary feathers and having the promise of a wing in the structure of their fore legs, and some time one of these animals may come to light; until then archæopteryx remains the earliest known bird. in the jurassic, then, when the dinosaurs were the lords of the earth and small mammals just beginning to appear, we come upon traces of full-fledged birds. the first intimation of their presence was the imprint of a single feather found in that ancient treasure-house, the solenhofen quarries; but as hercules was revealed by his foot, so the bird was made evident by the feather whose discovery was announced august , . and a little later, in september of the same year, the bird itself turned up, and in a second specimen was found, the two representing two species, if not two distinct genera. these were very different from any birds now living--so different, indeed, and bearing such evident traces of their reptilian ancestry, that it is necessary to place them apart from other animals in a separate division of the class birds. archæopteryx was considerably smaller than a crow, with a stout little head armed with sharp teeth (as scarce as hens' teeth was no joke in that distant period), while as he fluttered through the air he trailed after him a tail longer than his body, beset with feathers on either side. everyone knows that nowadays the feathers of a bird's tail are arranged like the sticks of a fan, and that the tail opens and shuts like a fan. but in archæopteryx the feathers were arranged in pairs, a feather on each side of every joint of the tail, so that on a small scale the tail was something like that of a kite; and because of this long, lizard-like tail this bird and his immediate kith and kin are placed in a group dubbed saururæ, or lizard tailed. because impressions of feathers are not found all around these specimens some have thought that they were confined to certain portions of the body--the wings, tail, and thighs--the other parts being naked. there seems, however, no good reason to suppose that such was the case, for it is extremely improbable that such perfect and important feathers as those of the wings and tail should alone have been developed, while there are many reasons why the feathers of the body might have been lost before the bird was covered by mud, or why their impressions do not show. it was a considerable time after the finding of the first specimen that the presence of teeth in the jaws was discovered, partly because the british museum specimen was imperfect,[ ] and partly because no one suspected that birds had ever possessed teeth, and so no one ever looked for them. when, in , a more complete example was found, the existence of teeth was unmistakably shown; but in the meantime, in february, , professor marsh had announced the presence of teeth in hesperornis, and so to him belongs the credit of being the discoverer of birds with teeth. [ ] _the skull was lacking, and a part of the upper jaw lying to one side was thought to belong to a fish._ the next birds that we know are from our own country, and although separated by an interval of thousands of years from the jurassic archæopteryx, time enough for the members of one group to have quite lost their wings, they still retain teeth, and in this respect the most bird-like of them is quite unlike any modern bird. these come from the chalk beds of western kansas, and the first specimens were obtained by professor marsh in his expeditions of and , but not until a few years later, after the material had been cleaned and was being studied, was it ascertained that these birds were armed with teeth. the smaller of these birds, which was apparently not unlike a small gull in general appearance, was, saving its teeth, so thoroughly a bird that it may be passed by without further notice, but the larger was remarkable in many ways. hesperornis, the western bird, was a great diver, in some ways the greatest of the divers, for it stood higher than the king penguin, though more slender and graceful in general build, looking somewhat like an overgrown, absolutely wingless loon. the penguins, as everyone knows, swim with their front limbs--we can't call them wings--which, though containing all the bones of a wing, have become transformed into powerful paddles; hesperornis, on the other hand, swam altogether with its legs--swam so well with them, indeed, that through disuse the wings dwindled away and vanished, save one bone. this, however, is not stating the theory quite correctly; of course the matter cannot be actually proved. hesperornis was a large bird, upwards of five feet in length, and if its ancestors were equally bulky their wings were quite too large to be used in swimming under water, as are those of such short-winged forms as the auks which fly under the water quite as much as they fly over it. hence the wings were closely folded upon the body so as to offer the least possible resistance, and being disused, they and their muscles dwindled, while the bones and muscles of the legs increased by constant use. by the time the wings were small enough to be used in so dense a medium as water the muscles had become too feeble to move them, and so degeneration proceeded until but one bone remained, a mere vestige of the wing that had been. the penguins retain their great breast muscles, and so did the great auk, because their wings are used in swimming, since it requires even more strength to move a small wing in water than it does to move a large wing in the thinner air. as for our domesticated fowls--the turkeys, chickens, and ducks--there has not been sufficient lapse of time for their muscles to dwindle, and besides artificial selection, the breeding of fowls for food has kept up the mere size of the muscles, although these lack the strength to be found in those of wild birds. as a swimming bird, one that swims with its legs and not with its wings, hesperornis has probably never been equalled, for the size and appearance of the bones indicate great power, while the bones of the foot were so joined to those of the leg as to turn edgewise as the foot was brought forward and thus to offer the least possible resistance to the water. it is a remarkable fact that the leg bones of hesperornis are hollow, remarkable because as a rule the bones of aquatic animals are more or less solid, their weight being supported by the water; but those of the great diver were almost as light as if it had dwelt upon the dry land. that it did not dwell there is conclusively shown by its build, and above all by its feet, for the foot of a running bird is modified in quite another way. the bird was probably covered with smooth, soft feathers, something like those of an apteryx; this we know because professor williston found a specimen showing the impression of the skin of the lower part of the leg as well as of the feathers that covered the "thigh" and head. while such a covering seems rather inadequate for a bird of such exclusively aquatic habits as hesperornis must have been, there seems no getting away from the facts in the case in the shape of professor williston's specimen, and we have in the snake bird, one of the most aquatic of recent birds, an instance of similarly poor covering. as all know who have seen this bird at home, its feathers shed the water very imperfectly, and after long-continued submersion become saturated, a fact which partly accounts for the habit the bird has of hanging itself out to dry. [illustration: fig. .--hesperornis, the great toothed diver. _from a drawing by j. m. gleeson._] the restoration which mr. gleeson has drawn differs radically from any yet made, and is the result of a careful study of the specimen belonging to the united states national museum. no one can appreciate the peculiarities of hesperornis and its remarkable departures from other swimming birds who has not seen the skeleton mounted in a swimming attitude. the great length of the legs, their position at the middle of the body, the narrowness of the body back of the hip joint, and the disproportionate length of the outer toe are all brought out in a manner which a picture of the bird squatting upon its haunches fails utterly to show. as for the tail, it is evident from the size and breadth of the bones that something of the kind was present; it is also evident that it was not like that of an ordinary bird, and so it has been drawn with just a suggestion of archæopteryx about it. the most extraordinary thing about hesperornis, however, is the position of the legs relative to the body, and this is something that was not even suspected until the skeleton was mounted in a swimming attitude. as anyone knows who has watched a duck swim, the usual place for the feet and legs is beneath and in a line with the body. but in our great extinct diver the articulations of the leg bones are such that this is impossible, and the feet and lower joint of the legs (called the tarsus) must have stood out nearly at right angles to the body, like a pair of oars. this is so peculiar and anomalous an attitude for a bird's legs that, although apparently indicated by the shape of the bones, it was at first thought to be due to the crushing and consequent distortion to which the bones had been subjected, and an endeavor was made to place the legs in the ordinary position, even though this was done at the expense of some little dislocation of the joints. but when the mounting of the skeleton had advanced further it became more evident that hesperornis was not an ordinary bird, and that he could not have swum in the usual manner, since this would have brought his great knee-caps up into his body, which would have been uncomfortable. and so, at the cost of some little time and trouble,[ ] the mountings were so changed that the legs stood out at the sides of the body, as shown in the picture. [ ] _the mounting of fossil bones is quite a different matter from the wiring of an ordinary skeleton, since the bones are not only so hard that they cannot be bored and wired like those of a recent animal, but they are so brittle and heavy that often they will not sustain their own weight. hence such bones must be supported from the outside, and to do this so that the mountings will be strong enough to support their weight, allow the bones to be removed for study, and yet be inconspicuous, is a difficult task._ a final word remains to be said about toothed birds, which is, that the visitor who looks upon one for the first time will probably be disappointed. the teeth are so loosely implanted in the jaw that most of them fall out shortly after death, while the few that remain are so small as not to attract observation. by the time the eocene period was reached, even before that, birds had become pretty much what we now see them, and very little change has taken place in them since that time; they seem to have become so exactly adapted to the conditions of existence that no further modification has taken place. this may be expressed in another way, by saying that while the mammals of the eocene have no near relatives among those now living, entire large groups having passed completely out of existence, the few birds that we know might, so far as their appearance and affinities go, have been killed yesterday. were we to judge of the former abundance of birds by the number we find in a fossil state, we should conclude that in the early days of the world they were remarkably scarce, for bird bones are among the rarest of fossils. but from the high degree of development evidenced by the few examples that have come to light, and the fact that these represent various and quite distinct species,[ ] we are led to conclude that birds were abundant enough, but that we simply do not find them. [ ] _but three birds, besides a stray feather or two, are so far known from the eocene of north america. one of these is a fowl not very unlike some of the small curassows of south america; another is a little bird, supposed to be related to the sparrows, while the third is a large bird of uncertain relationships._ several eggs, too--or, rather, casts of eggs--have lately been found in the cretaceous and miocene strata of the west; and, as eggs and birds are usually associated, we are liable at any time to come upon the bones of the birds that laid them. to the writer's mind no thoroughly satisfactory explanation has been given for the scarcity of bird remains; but the reason commonly advanced is that, owing to their lightness, dead birds float for a much longer time than other animals, and hence are more exposed to the ravages of the weather and the attacks of carrion-feeding animals. it has also been said that the power of flight enabled birds to escape calamities that caused the death of contemporary animals; but all birds do not fly; and birds do fall victims to storms, cold, and starvation, and even perish of pestilence, like the cormorants of bering island, whose ranks have twice been decimated by disease. it is true that where carnivorous animals abound, dead birds do disappear quickly; and my friend dr. stejneger tells me that, while hundreds of dead sea-fowl are cast on the shores of the commander islands, it is a rare thing to find one after daylight, as the bodies are devoured by the arctic foxes that prowl about the shores at night. but, again, as in the miocene of southern france and in the pliocene of oregon, remains of birds are fairly numerous, showing that, under proper conditions, their bones are preserved for future reference, so that we may hope some day to come upon specimens that will enable us to round out the history of bird life in the past. _references_ _the first discovered specimen of archæopteryx, archæopteryx macrura, is in the british museum, the second more complete example is in the royal museum of natural history, berlin. the largest collection of toothed birds, including the types of hesperornis, ichthyornis and others, is in the yale university museum, at new haven. the united states national museum at washington has a fine mounted skeleton of hesperornis, and the state university of kansas, at lawrence, has the example showing the impressions of feathers._ _for scientific descriptions of these birds the reader is referred to owen's paper "on the archæopteryx of von meyer, with a description of the fossil remains, etc.," in the "transactions of the philosophical society of london for ," page , and "odontornithes, a monograph of the extinct toothed birds of north america," by o. c. marsh. much popular and scientific information concerning the early birds is to be found in newton's "dictionary of birds," and "the story of bird life," by w. p. pycraft; the "structure and life of birds," by f. w. headley; "the story of the birds," by j. newton baskett._ [illustration: fig. .--archæopteryx as restored by mr. pycraft.] vi the dinosaurs "_shapes of all sorts and sizes, great and small._" a few million years ago, geologists and physicists do not agree upon the exact number, although both agree upon the millions, when the rocky mountains were not yet born and the now bare and arid western plains a land of lakes, rivers, and luxuriant vegetation, the region was inhabited by a race of strange and mighty reptiles upon whom science has bestowed the appropriate name of dinosaurs, or terrible lizards. our acquaintance with the dinosaurs is comparatively recent, dating from the early part of the nineteenth century, and in america, at least, the date may be set at , when the first dinosaur remains were found in the valley of the connecticut, although they naturally were not recognized as such, nor had the term been devised. the first dinosaur to be formally recognized as representing quite a new order of reptiles was the carnivorous megalosaur, found near oxford, england, in . [illustration: fig. .--thespesius. a common herbivorous dinosaur of the cretaceous. _from a drawing by charles r. knight._] for a long time our knowledge of dinosaurs was very imperfect and literally fragmentary, depending mostly upon scattered teeth, isolated vertebræ, or fragments of bone picked up on the surface or casually encountered in some mine or quarry. now, however, thanks mainly to the labors of american palæontologists, thanks also to the rich deposits of fossils in our western states, we have an extensive knowledge of the dinosaurs, of their size, structure, habits, and general appearance. there are to-day no animals living that are closely related to them; none have lived for a long period of time, for the dinosaurs came to an end in the cretaceous, and it can only be said that the crocodiles, on the one hand, and the ostriches, on the other, are the nearest existing relatives of these great reptiles. for, though so different in outward appearance, birds and reptiles are structurally quite closely allied, and the creeping snake and the bird on which it preys are relatives, although any intimate relationship between them is of the serpent's making, and is strongly objected to by the bird. but if we compare the skeleton of a dinosaur with that of an ostrich--a young one is preferable--and with those of the earlier birds, we shall find that many of the barriers now existing between reptiles and birds are broken down, and that they have many points in common. in fact, save in the matter of clothes, wherein birds differ from all other animals, the two great groups are not so very far apart. the dinosaurs were by no means confined to north america, although the western united states seem to have been their headquarters, but ranged pretty much over the world, for their remains have been found in every continent, even in far-off new zealand. in point of time they ranged from the trias to the upper cretaceous, their golden age, marking the culminating point of reptilian life, being in the jurassic, when huge forms stalked by the sea-shore, browsed amid the swamps, or disported themselves along the reedy margins of lakes and rivers. they had their day, a day of many thousand years, and then passed away, giving place to the superior race of mammals which was just springing into being when the huge dinosaurs were in the heyday of their existence. and it does seem as if in the dim and distant past, as in the present, brains were a potent factor in the struggle for supremacy; for, though these reptiles were giants in size, dominating the earth through mere brute force, they were dwarfs in intellect. the smallest human brain that is thought to be compatible with life itself weighs a little over ten ounces, the smallest that can exist with reasoning powers is two pounds; this in a creature weighing from to pounds. what do we find among dinosaurs? thespesius, or claosaurus, which may have walked where baltimore now stands, was twenty-five feet in length and stood a dozen feet high in his bare feet, had a brain smaller than a man's clenched fist, weighing less than one pound. brontosaurus, in some respects the biggest brute that ever walked, was but little better off, and triceratops, and his relatives, creatures having twice the bulk of an elephant, weighing probably over ten tons, possessed a brain weighing not over two pounds! how much of what we term intelligence could such a creature possess--what was the extent of its reasoning powers? judging from our own standpoint and the small amount of intellect apparent in some humans with much larger brains, these big reptiles must have known just about enough to have eaten when they were hungry, anything more was superfluous. however, intelligence is one thing, life another, and the spinal cord, with its supply of nerve-substance, doubtless looked after the mere mechanical functions of life; and while even the spinal cord is in many cases quite small, in some places, particularly in the sacral region, it is subject to considerable enlargement. this is notably true of stegosaurus, where the sacral enlargement is twenty times the bulk of the puny brain--a fact noted by professor marsh, and seized upon by the newspapers, which announced that he had discovered a dinosaur with a brain in its pelvis. in their great variety of size and shape the dinosaurs form an interesting parallel with the marsupials of australia. for just as these are, as it were, an epitome of the class of mammals, mimicking the herbivores, carnivores, rodents and even monkeys, so there are carnivorous and herbivorous dinosaurs--dinosaurs that dwelt on land and others that habitually resided in the water, those that walked upright and those that crawled about on all fours; and, while there are no hints that any possessed the power of flight, some members of the group are very bird-like in form and structure, so much so that it has been thought that the two may have had a common ancestry. the smallest of the dinosaurs whose acquaintance we have made were little larger than chickens; the largest claim the distinction of being the largest known quadrupeds that have walked the face of the earth, the giants not only of their day, but of all time, before whose huge frames the bones of the mammoth, that familiar byword for all things great, seem slight. for brontosaurus, the thunder lizard, beneath whose mighty tread the earth shook, and his kindred were from to feet long and to feet high, their thigh bones measuring to feet in length, being the largest single bones known to us, while some of the vertebræ were - / feet high, exceeding in dimensions those of a whale. [illustration: fig. --a hind leg of the great brontosaurus, the largest of the dinosaurs.] the group to which brontosaurus belongs, including diplodocus and morosaurus, is distinguished by a large, though rather short, body, very long neck and tail, and, for the size of the animal, a very small head. in fact, the head was so small and, in the case of diplodocus, so poorly provided with teeth that it must have been quite a task, or a long-continued pleasure, according to the state of its digestive apparatus, for the animal to have eaten its daily meal. [illustration: fig. .--a single vertebra of brontosaurus.] an elephant weighing tons eats pounds of hay and pounds of grain for his day's ration; but, as this food is in a comparatively concentrated form, it would require at least twice this weight of green fodder. it is a difficult matter to estimate the weight of a live diplodocus or a brontosaurus, but it is pretty safe to say that it would not be far from tons, and that one would devour at the very least something over pounds of leaves or twigs or plants each day--more, if the animal felt really hungry. but here we must, even if reluctantly, curb our imagination a little and consider another point: the cold-blooded, sluggish reptiles, as we know them to-day, do not waste their energies in rapid movements, or in keeping the temperature of their bodies above that of the air, and so by no means require the amount of food needed by more active, warm-blooded animals. alligators, turtles, and snakes will go for weeks, even months, without food, and while this applies more particularly to those that dwell in temperate climes and during their winter hibernation practically suspend the functions of digestion and respiration, it is more or less true of all reptiles. and as there is little reason for supposing that reptiles behaved in the past any differently from what they do in the present, these great dinosaurs may, after all, not have been gifted with such ravenous appetites as one might fancy. still, it is dangerous to lay down any hard and fast laws concerning animals, and he who writes about them is continually obliged to qualify his remarks--in sporting parlance, to hedge a little, and in the present instance there is some reason, based on the arrangement of vertebræ and ribs, to suppose that the lungs of dinosaurs were somewhat like those of birds, and that, as a corollary, their blood may have been better aërated and warmer than that of living reptiles. but, to return to the question of food. from the peculiar character of the articulations of the limb-bones, it is inferred that these animals were largely aquatic in their habits, and fed on some abundant species of water plants. one can readily see the advantage of the long neck in browsing off the vegetation on the bottom of shallow lakes, while the animal was submerged, or in rearing the head aloft to scan the surrounding shores for the approach of an enemy. or, with the tail as a counterpoise, the entire body could be reared out of water and the head be raised some thirty feet in the air. triceratops, he of the three-horned face, had a remarkable skull which projected backward over the neck, like a fireman's helmet, or a sunbonnet worn hind side before, while over each eye was a massive horn directed forward, a third, but much smaller horn being sometimes present on the nose. the little "horned toad," which isn't a toad at all, is the nearest suggestion we have to-day of triceratops; but, could he realize the ambition of the frog in the fable and swell himself to the dimensions of an ox, he would even then be but a pigmy compared with his ancient and distant relative. so far as mere appearance goes he would compare very well, for while so much is said about the strange appearance of the dinosaurs, it is to be borne in mind that their peculiarities are enhanced by their size, and that there are many lizards of to-day that lack only stature to be even more _bizarre_; and, for example, were the australian moloch but big enough, he could give even stegosaurus "points" in more ways than one. standing before the skull of triceratops, looking him squarely in the face, one notices in front of each eye a thick guard of projecting bone, and while this must have interfered with vision directly ahead it must have also furnished protection for the eye. so long as triceratops faced an adversary he must have been practically invulnerable, but as he was the largest animal of his time, upward of twenty-five feet in length, it is probable that his combats were mainly with those of his own kind and the subject of dispute some fair female upon whom two rival suitors had cast covetous eyes. what a sight it would have been to have seen two of these big brutes in mortal combat as they charged upon each other with all the impetus to be derived from ten tons of infuriate flesh! we may picture to ourselves horn clashing upon horn, or glancing from each bony shield until some skilful stroke or unlucky slip placed one combatant at the mercy of the other, and he went down before the blows of his adversary "as falls on mount alvernus a thunder-smitten oak." [illustration: fig. .--moloch. a modern lizard that surpasses the stegosaurs in all but size. _from a drawing by j. m. gleeson._] a pair of triceratops horns in the national museum bears witness to such encounters, for one is broken midway between tip and base; and that it was broken during life is evident from the fact that the stump is healed and rounded over, while the size of the horns shows that their owner reached a ripe old age. for, unlike man and the higher vertebrates, reptiles and fishes do not have a maximum standard of size which is soon reached and rarely exceeded, but continue to grow throughout life, so that the size of a turtle, a crocodile, or a dinosaur tells something of the duration of its life. before quitting triceratops let us glance for a moment at its skeleton. now among other things a skeleton is the solution of a problem in mechanics, and in triceratops the head so dominates the rest of the structure that one might almost imagine the skull was made first and the body adjusted to it. the great head seems made not only for offence and defence; the spreading frill serves for the attachment of muscles to sustain the weight of the skull, while the work of the muscles is made easier by the fact that the frill reaches so far back of the junction of head with neck as to largely counterbalance the weight of the face and jaws. when we restored the skull of this animal it was found that the centre of gravity lay back of the eye. several of the bones of the neck are united in one mass to furnish a firm attachment for the muscles that support and move the skull, but as the movements of the neck are already restricted by the overhanging frill, this loss of motion is no additional disadvantage. [illustration: triceratops prorsus marsh fig. .--skeleton of triceratops.] to support all this weight of skull and body requires very massive legs, and as the fore legs are very short, this enables triceratops to browse comfortably from the ground by merely lowering the front of the head. these forms we have been considering were the giants of the group, but a commoner species, thespesius, though less in bulk than those just mentioned, was still of goodly proportions, for, as he stalked about, the top of his head was twelve feet from the ground. thespesius and his kin seem to have been comparatively abundant, for they have a wide distribution, and many specimens, some almost perfect, have been discovered in this country and abroad. no less than twenty-nine iguanodons, a european relative of thespesius, were found in one spot in mining for coal at bernissart, belgium. here, during long years of cretaceous time, a river slowly cut its way through the coal-bearing strata to a depth of feet, a depth almost twice as great as the deepest part of the gorge of niagara, and then, this being accomplished, began the work of filling up the valley it had excavated. it was then a sluggish stream with marshy borders, a stream subject to frequent floods, when the water, turbid with mud and laden with sand, overflowed its banks, leaving them, as the waters subsided, covered thickly with mud. here, amidst the luxuriant vegetation of a semi-tropical climate, lived and died the iguanodons, and here the pick of the miner rescued them from their long entombment to form part of the treasures of the museum at brussels. like other reptiles, living and extinct, thespesius was continually renewing his teeth, so that as fast as one tooth was worn out it was replaced by another, a point wherein thespesius had a decided advantage over ourselves. on the other hand, as there was a reserve supply of something like teeth in the lower jaw alone, what an opportunity for the toothache! and then we have a multitude of lesser dinosaurs, including the active, predatory species with sharp claws and double-edged teeth. megalosaurus, the first of the dinosaurs to be really known, was one of these carnivorous species, and from our west comes a near relative, ceratosaurus, the nose-horned lizard, a queer beast with tiny fore legs, powerful, sharp-clawed hind feet, and well-armed jaws. a most formidable foe he seems, the more that the hollow bones speak of active movements, and professor cope pictured him, or a near relative, vigorously engaged in combat with his fellows, or preying upon the huge but helpless herbivores of the marshes, leaping, biting, and tearing his enemy to pieces with tooth and claw. professor osborn, on the other hand, is inclined to consider him as a reptilian hyena, feeding upon carrion, although one can but feel that such an armament is not entirely in the interests of peace. last, but by no means least, are the stegosaurs, or plated lizards, for not only were they beasts of goodly size, but they were among the most singular of all known animals, singular even for dinosaurs. they had diminutive heads, small fore legs, long tails armed on either side near the tip, with two pairs of large spines, while from these spines to the neck ran series of large, but thin, and sharp-edged plates standing on edge, so that their backs looked like the bottom of a boat provided with a number of little centreboards. just how these plates were arranged is not decided beyond a peradventure, but while originally figured as having them in a single series down the back it seems much more probable that they formed parallel rows. [illustration: fig. .--the horned ceratosaurus. a carnivorous dinosaur. _from a drawing by j. m. gleeson._] the largest of these plates were two feet in height and length, and not more than an inch thick, except at the base, where they were enlarged and roughened to give a firm hold to the thick skin in which they were imbedded. be it remembered, too, that these plates and spines were doubtless covered with horn, so that they were even longer in life than as we now see them. the tail spines varied in length, according to the species, from eight or nine inches to nearly three feet, and some of them have a diameter of six inches at the base. they were swung by a tail eight to ten feet long, and as a visitor was heard to remark, one wouldn't like to be about such an animal in fly time. such were some of the strange and mighty animals that once roamed this continent from the valley of the connecticut, where they literally left their footprints on the sands of time, to the rocky mountains, where the ancient lakes and rivers became cemeteries for the entombment of their bones. the labor of the collector has gathered their fossil remains from many a western canyon, the skill of the preparator has removed them from their stony sepulchres and the study of the anatomist has restored them as they were in life. _references._ _most of our large museums have on exhibition fine specimens of many dinosaurs, comprising skulls, limbs, and large portions of their skeletons. the american museum of natural history, new york, has the largest and finest display. the first actual skeleton of a dinosaur to be mounted in this country was the splendid claosaurus at the yale university museum, where other striking pieces are also to be seen. the mounting of this claosaurus, which is feet long and feet high, took an entire year. the united states national museum is particularly rich in examples of the great, horned triceratops, while the carnegie museum, pittsburgh, has the best diplodocus. the field columbian museum and the universities of wyoming and colorado all have good collections._ [illustration: fig. .--stegosaurus. an armored dinosaur of the jurassic. _from a drawing by charles r. knight._] _the largest single bone of a dinosaur is the thigh bone of a brontosaurus in the field columbian museum, this measuring feet inches in length. the height of a complete hind leg in the american museum of natural history is feet, while a single claw measures by inches. the skeleton of triceratops restored in papier-maché for the pan-american exposition measured feet from tip of nose to end of tail and was feet inches to the top of the backbone over the hips, this being the highest point. the head in the united states national museum used as a model is feet inches long in a straight line and feet inches across the frill. there is a skull in the yale university museum even larger than this._ _articles relating to dinosaurs are mostly technical in their nature and scattered through various scientific journals. the most accessible probably is "the dinosaurs of north america," by professor o. c. marsh, published as part of the sixteenth annual report of the united states geological survey. this contains many figures of the skulls, bones, and entire skeletons of many dinosaurs._ [illustration: fig. .--skull of ceratosaurus. _from a specimen in the united states national museum._] vii reading the riddles of the rocks "_and the first morning of creation wrote what the last dawn of reckoning shall read._" it is quite possible that the reader may wish to know something of the manner in which the specimens described in these pages have been gathered, how we acquire our knowledge of brontosaurus, claosaurus, or any of the many other "sauruses," and how their restorations have been made. there was a time, not so very long ago, when fossils were looked upon as mere sports of nature, and little attention paid to them; later their true nature was recognized, though they were merely gathered haphazard as occasion might offer. but now, and for many years past, the fossil-bearing rocks of many parts of the world have been systematically worked, and from the material thus obtained we have acquired a great deal of information regarding the inhabitants of the ancient world. this is particularly true of our own western country, where a vast amount of collecting has been done, although very much remains to be done in the matter of perfecting this knowledge, and hosts of new animals remain to be discovered. for this information we are almost as much indebted to the collector who has gathered the needed material, and the preparator whose patience and skill have made it available for study, as to the palæontologist who has interpreted the meaning of the bones. to collect successfully demands not only a knowledge of the rocks in which fossils occur and of the localities where they are best exposed to view, but an eye quick to detect a piece of bone protruding from a rock or lying amongst the shale, and, above all, the ability to work a deposit to advantage after it has been found. the collector of living animals hies to regions where there is plenty for bird and beast to eat and drink, but the collector of extinct animals cares little for what is on the surface of the earth; his great desire is to see as much as possible of what may lie beneath. so the prospector in search of fossils betakes himself to some region where the ceaseless warfare waged by water against the dry land has seamed the face of the earth with countless gullies and canyons, or carved it into slopes and bluffs in which the edges of the bone-bearing strata are exposed to view, and along these he skirts, ever on the look-out for some projecting bit of bone. the country is an almost shadeless desert, burning hot by day, uncomfortably cool at night. water is scarce, and when it can be found, often has little to commend it save wetness; but the collector is buoyed up through all this with the hope that he may discover some creature new to science that shall not only be bigger and uglier and stranger than any heretofore found, but shall be the long-sought form needed for the solution of some difficult problem in the history of the past. now collecting is a lottery, differing from most lotteries, however, in that while some of the returns may be pretty small, there are few absolute blanks and some remarkably large prizes, and every collector hopes that it may fall to his lot to win one of these, and is willing to work long and arduously for the chance of obtaining it. it may give some idea of the chances to say that some years ago dr. wortman spent almost an entire season in the field without success, and then, at the eleventh hour, found the now famous skeleton of phenacodus, or that a party from princeton actually camped within yards of a rich deposit of rare fossils and yet failed to discover it. let us, however, suppose that the reconnaissance has been successful, and that an outcrop of bone has been found, serving like a tombstone carven with strange characters to indicate the burial-place of some primeval monster. possibly nature long ago rifled the grave, washing away much of the skeleton, and leaving little save the fragments visible on the surface; on the other hand, these pieces may form part of a complete skeleton, and there is no way to decide this important question save by actual excavation. the manner of disinterment varies, but much depends on whether the fossil lies in comparatively loose shale or is imbedded in the solid rock, whether the strata are level or dip downward into the hillside. if, unfortunately, this last is the case, it necessitates a careful shoring up of the excavation with props of cotton-wood or such boards as may have been brought along to box specimens, or it may even be necessary to run a short tunnel in order to get at some coveted bone. should the specimen lie in shale, as is the case with most of the large reptiles that have been collected, much of that work may be done with pick and shovel; but if it is desirable or necessary to work in firm rock, drills and hammers, wedges, even powder, may be needed to rend from nature her long-kept secrets. in any event, a detailed plan is made of the excavation, and each piece of bone or section of rock duly recorded therein by letter and number, so that later on the relation of the parts to one another may be known, or the various sections assembled in the work-room exactly as they lay in the quarry. bones which lie in loose rock are often, one might say usually, more or less broken, and when a bone three, four, or even six feet long, weighing anywhere from to , pounds, has been shattered to fragments the problem of removing it is no easy one. but here the skill of the collector comes into play to treat the fossil as a surgeon treats a fractured limb, to cover it with plaster bandages, and brace it with splints of wood or iron so that the specimen may not only be taken from the ground but endure in safety the coming journey of a thousand or more miles. for simpler cases or lighter objects strips of sacking, or even paper, applied with flour and water, suffice, or pieces of sacking soaked in thin plaster may be laid over the bone, first covering it with thin paper in order that the plaster jacket may simply stiffen and not adhere to it. collecting has not always been carried on in this systematic manner, for the development of the present methods has been the result of years of experience; formerly there was a mere skimming-over of the surface in what professor marsh used to term the potato-gathering style, but now the effort is made to remove specimens intact, often imbedded in large masses of rock, in order that all parts may be preserved. we will take it for granted that our specimens have safely passed through all perils by land and water, road and rail; that they have been quarried, boxed, carted over a roadless country to the nearest railway, and have withstood , miles of jolting in a freight-car. the first step in reconstruction has been taken; the problem, now that the boxes are reposing on the work-room floor, is to make the blocks of stone give up the secrets they have guarded for ages, to free the bones from their enveloping matrix in order that they may tell us something of the life of the past. the method of doing this varies with the conditions under which the material has been gathered, and if from hard clay, chalk, or shale, the process, though tedious enough at best, is by no means so difficult as if the specimens are imbedded in solid rock. in this case the fragments from a given section of quarry must be assembled according to the plan which has been carefully made as the work of exhumation progressed, all pieces containing bone must be stuck together, and weak parts strengthened with gum or glue. now the mass is attacked with hammer and chisel, and the surrounding matrix slowly and carefully cut away until the contained bone is revealed, a process much simpler and more expeditious in the telling than in the actuality; for the preparator may not use the heavy tools of the ordinary stone-cutter: sometimes an awl, or even a glover's needle, must suffice him, and the chips cut off are so small and such care must be taken not to injure the bone that the work is really tedious. this may, perhaps, be better appreciated by saying that to clean a single vertebra of such a huge dinosaur as diplodocus may require a month of continuous labor, and that a score of these big and complicated bones, besides others of simpler structure, are included in the backbone. the finished specimen weighs over pounds, while as originally collected, with all the adherent rock, the weight was twice or thrice as great. such a mass as this is comparatively small, and sometimes huge blocks are taken containing entire skulls or a number of bones, and not infrequently weighing a ton. the largest single specimen is a skull of triceratops, collected by mr. j. b. hatcher, which weighed, when boxed, , pounds. or, as the result of some mishap, or through the work of an inexperienced collector, a valuable specimen may arrive in the shape of a box full of irregular fragments of stone compared with which a dissected map or an old-fashioned chinese puzzle is simplicity itself, and one may spend hours looking for some piece whose proper location gives the clew to an entire section, and days, even, may be consumed before the task is completed. while this not only tries the patience, but the eyes as well, there is, nevertheless, a fascination about this work of fashioning a bone out of scores, possibly hundreds, of fragments, and watching the irregular bits of stone shaping themselves into a mosaic that forms a portion of some creature, possibly quite new to science, and destined to bear a name as long as itself. and thus, after many days of toil, the bone that millions of years before sank into the mud of some old lake-bottom or was buried in the sandy shoals of an ancient river, is brought to light once more to help tell the tale of the creatures of the past. one bone might convey a great deal of information; on the other hand it might reveal very little; for, while it is very painful to say so, the popular impression that it is possible to reconstruct an animal from a single bone, or tell its size and habits from a tooth is but partially correct, and sometimes "the eminent scientist" has come to grief even with a great many bones at his disposal. did not one of the ablest anatomists describe and figure the hip-bones of a dinosaur as its shoulder-blade, and another, equally able, reconstruct a reptile "hind side before," placing the head on the tail! this certainly sounds absurd enough; but just as absurd mistakes are made by men in other walks of life, often with far more deplorable results. before passing to the restoration of the exterior of animals it may be well to say something of the manner in which the skeleton of an extinct animal may be reconstructed and the meaning of its various parts interpreted. for the adjustment of the muscles is dependent on the structure of the skeleton, and putting on the muscles means blocking out the form, details of external appearance being supplied by the skin and its accessories of hair, scales, or horns. let us suppose in the present instance that we are dealing with one of the great reptiles known as triceratops whose remains are among the treasures of the national museum at washington, for the reconstruction of the big beast well illustrates the methods of the palæontologist and also the troubles by which he is beset. moreover, this is not a purely imaginary case, but one that is very real, for the skeleton of this animal which was shown at buffalo was restored in papier-maché in exactly the manner indicated. we have a goodly number of bones, but by no means an entire skeleton, and yet we wish to complete the skeleton and incidentally to form some idea of the creature's habits. now we can interpret the past only by a knowledge of the present, and it is by carefully studying the skeletons of the animals of to-day that we can learn to read the meaning of the symbols of bones left by the animals of a million yesterdays. thus we find that certain characters distinguish the bone of a mammal from that of a bird, a reptile, or a fish, and these in turn from one another, and this constitutes the a b c of comparative anatomy. and, in a like manner, the bones of the various divisions of these main groups have to a greater or less extent their own distinguishing characteristics, so that by first comparing the bones of extinct animals with those of creatures that are now living we are enabled to recognize their nearest existing relative, and then by comparing them with one another we learn the relations they bore in the ancient world. but it must be borne in mind that some of the early beasts were so very different from those of to-day that until pretty much their entire structure was known there was nothing with which to compare odd bones. had but a single incomplete specimen of triceratops come to light we should be very much in the dark concerning him; and although remains of some thirty individuals have been discovered, these have been so imperfect that we are very far from having all the information we need. a great part of the head, with its formidable looking horns, is present, and although the nose is gone, we know from other specimens that it, too, was armed with a knob, or horn, and that the skull ended in a beak, something like that of a snapping turtle, though formed by a separate and extra bone; similarly the end of the lower jaw is lacking, but we may be pretty certain that it ended in a beak, to match that of the skull. the large leg-bones of our specimen are mostly represented, for these being among the more solid parts of the skeleton are more frequently preserved than any others, and though some are from one side and some from another, this matters not. if the hind legs were disproportionately long it would indicate that our animal often or habitually walked erect, but as there is only difference enough between the fore and hind limbs to enable triceratops to browse comfortably from the ground we would naturally place him on all fours, even were the skull not so large as to make the creature too top-heavy for any other mode of locomotion. were the limbs very small in comparison with the other bones, it would obviously mean that their owner passed his life in the water. for a skeleton has a twofold meaning, it is the best, the most enduring, testimony we have as to an animal's place in nature and the relationships it sustains to the creatures that lived with it, before it, and after it. more than this, a skeleton is the solution of a problem in mechanics, the problem of carrying a given weight and of adaptation to a given mode of life. thus the skeleton varies according as a creature dwells on land, in the water, or in the air, and according as it feeds on grass or preys upon its fellows. and so the mechanics of a skeleton afford us a clew to the habits of the living animal. something, too, may be gathered from the structure of the leg-bones, for solid bones mean either a sluggish animal or a creature of more or less aquatic habits, while hollow bones emphatically declare a land animal, and an active one at that; and this, in the case of the dinosaurs, hints at predatory habits, the ability to catch and eat their defenceless and more sluggish brethren. a claw, or, better yet, a tooth, may confirm or refute this hint; for a blunt claw could not be used in tearing prey limb from limb, nor would a double-edged tooth, made for rending flesh, serve for champing grass. but few bones of the feet, and especially the fore feet, are present, these smaller parts of the skeleton having been washed away before the ponderous frame was buried in the sand, and the best that can be done is to follow the law of probabilities and put three toes on the hind foot and five on the fore, two of these last without claws. the single blunt round claw among our bones shows, as do the teeth, that triceratops was herbivorous; it also pointed a little downward, and this tells that in the living animal the sole of the foot was a thick, soft pad, somewhat as it is in the elephant and rhinoceros, and that the toes were not entirely free from one another. there are less than a dozen vertebræ and still fewer ribs, besides half a barrelful of pieces, from which to reconstruct a backbone twenty feet long. that the ribs are part from one side and part from another matters no more than it did in the case of the leg-bones; but the backbone presents a more difficult problem, since the pieces are not like so many checkers--all made after one pattern--but each has an individuality of its own. the total number of vertebræ must be guessed at (perhaps it would sound better to say estimated, but it really means the same), and knowing that some sections are from the front part of the vertebral column and some from the back, we must fill in the gaps as best we may. the ribs offer a little aid in this task, giving certain details of the vertebræ, while those in turn tell something about the adjoining parts of the ribs. we finish our triceratops with a tail of moderate length, as indicated by the rapid taper of the few vertebræ available, and from these we gather, too, that in life the tail was round, and not flattened, and that it neither served for swimming nor for a balancing pole. and so, little by little, have been pieced together the fragments from which we have derived our knowledge of the past, and thus has the palæontologist read the riddles of the rocks. [illustration: fig. .--triceratops, he of the three-horned face. _from a statuette by charles r. knight._] to make these dry bones live again, to clothe them with flesh and reconstruct the creature as he was or may have been in life, is, to be honest, very largely guesswork, though to make a guess that shall come anywhere near the mark not only demands a thorough knowledge of anatomy--for the basis of all restoration must be the skeleton--but calls for more than a passing acquaintance with the external appearance of living animals. and while there is nothing in the bones to tell how an animal is, or was, clad, they will at least show to what group the creature belonged, and, that known, there are certain probabilities in the case. a bird, for example, would certainly be clad in feathers. going a little farther, we might be pretty sure that the feathers of a water-fowl would be thick and close; those of strictly terrestrial birds, such as the ostrich and other flightless forms, lax and long. these as general propositions; of course, in special cases, one might easily come to grief, as in dealing with birds like penguins, which are particularly adapted for an aquatic life, and have the feathers highly modified. these birds depend upon their fat, and not on their feathers, for warmth, and so their feathers have become a sort of cross between scales and hairs. hair and fur belong to mammals only, although these creatures show much variety in their outer covering. the thoroughly marine whales have discarded furs and adopted a smooth and slippery skin,[ ] well adapted to movement through the water, relying for warmth on a thick undershirt of blubber. the earless seals that pass much of their time on the ice have just enough hair to keep them from absolute contact with it, warmth again being provided for by blubber. the fur seals, which for several months in the year dwell largely on land, have a coat of fur and hair, although warmth is mostly furnished, or rather kept in, by fat. [ ] _the reader is warned that this is a mere figure of speech, for, of course, the process of adaptation to surroundings is passive, not active, although there is a most unfortunate tendency among writers on evolution, and particularly on mimicry, to speak of it as active. the writer believes that no animal in the first stages of mimicry, consciously mimics or endeavors to resemble another animal or any part of its surroundings, but a habit at first accidental may in time become more or less conscious._ no reptile, therefore, would be covered with feathers, neither, judging from those we know to-day, would they be clad in fur or hair; but, such coverings being barred out, there remain a great variety of plates and scales to choose from. folds and frills, crests and dewlaps, like beauty, are but skin deep, and, being thus superficial, ordinarily leave no trace of their former presence, and in respect to them the reconstructor must trust to his imagination, with the law of probabilities as a check rein to his fancy. this law would tell us that such ornaments must not be so placed as to be in the way, and that while there would be a possibility--one might even say probability--of the great, short-headed, iguana-like dinosaurs having dewlaps, that there would be no great likelihood of their possessing ruffs such as that of the australian chlamydosaurus (mantled lizard) to flap about their ears. even stegosaurus, with his bizarre array of great plates and spines, kept them on his back, out of the way. such festal ornamentation would, however, more likely be found in small, active creatures, the larger beasts contenting themselves with plates and folds. spines and plates usually leave some trace of their existence, for they consist of a super-structure of skin or horn, built on a foundation of bone; and while even horn decomposes too quickly to "petrify," the bone will become fossilized and changed into enduring stone. but while this affords a pretty sure guide to the general shape of the investing horn, it does not give all the details, and there may have been ridges and furrows and sculpturing that we know not of. knowing, then, what the probabilities are, we have some guide to the character of the covering that should be placed on an animal, and if we may not be sure as to what should be done, we may be pretty certain what should not. for example, to depict a dinosaur with smooth, rubbery hide walking about on dry land would be to violate the probabilities, for only such exclusively aquatic creatures as the whales among mammals, and the salamanders among batrachians, are clothed in smooth, shiny skin. there might, however, be reason to suspect that a creature largely aquatic in its habits did occasionally venture on land, as, for instance, when vertebræ that seem illy adapted for carrying the weight of a land animal are found in company with huge limb-bones and massive feet we may feel reasonably certain that their owner passed at least a portion of his time on _terra firma_. so much for the probabilities as to the covering of animals known to us only by their fossil remains; but it is often possible to go beyond this, and to state certainly how they were clad. for while the chances are small that any trace of the covering of an extinct animal, other than bony plates, will be preserved, nature does now and then seem to have relented, and occasionally some animal settled to rest where it was so quickly and quietly covered with fine mud that the impression of small scales, feathers, or even smooth skin, was preserved; curiously enough, there seems to be scarcely any record of the imprint of hair. then, too, it is to be remembered that while the chances were very much against such preservation, in the thousands or millions of times creatures died the millionth chance might come uppermost. silhouettes of those marine reptiles, the ichthyosaurs, have been found, probably made by the slow carbonization of animal matter, showing not only the form of the body and tail, but revealing the existence of an unsuspected back fin. and yet these animals were apparently clad in a skin as thin and smooth as that of a whale. impressions of feathers were known long before the discovery of archæopteryx; a few have been found in the green river and florissant shales of wyoming, and a hesperornis in the collection of the state university of kansas shows traces of the existence of long, soft feathers on the legs and very clear imprints of the scales and reticulated skin that covered the tarsus. from the chalk of kansas, too, came the example of tylosaur, showing that the back of this animal was decorated with the crest shown in mr. knight's restoration, one not unlike that of the modern iguana. from the laramie sandstone of montana mr. hatcher and mr. butler have obtained the impressions of portions of the skin of the great dinosaur, thespesius, which show that the covering of this animal consisted largely, if not entirely, of small, irregularly hexagonal horny scutes, slightly thickened in the centre. the quarries of lithographic stone at solenhofen have yielded a few specimens of flying reptiles, pterodactyls, which not only verify the correctness of the inference that these creatures possessed membranous wings, like the bats, but show the exact shape, and it was sometimes very curious, of this membrane. and each and all of these wonderfully preserved specimens serve both to check and guide the restorer in his task of clothing the animal as it was in life. and all this help is needed, for it is an easy matter to make a wide-sweeping deduction, apparently resting on a good basis of fact, and yet erroneous. remains of the mammoth and woolly rhinoceros, found in siberia and northern europe, were thought to indicate that at the period when these animals lived the climate was mild, a very natural inference, since the elephants and rhinoceroses we now know are all inhabitants of tropical climes. but the discovery of more or less complete specimens makes it evident that the climate was not particularly mild; the animals were simply adapted to it; instead of being naked like their modern relatives, they were dressed for the climate in a woolly covering. we think of the tiger as prowling through the jungles of india, but he ranges so far north that in some localities this beast preys upon reindeer, which are among the most northern of large mammals, and there the tiger is clad in fairly thick fur. when we come to coloring a reconstructed animal we have absolutely no guide, unless we assume that the larger a creature the more soberly will it be colored. the great land animals of to-day, the elephant and rhinoceros, to say nothing of the aquatic hippopotamus, are very dully colored, and while this sombre coloration is to-day a protection, rendering these animals less easily seen by man than they otherwise would be, yet at the time this color was developing man was not nor were there enemies sufficiently formidable to menace the race of elephantine creatures. for where mere size furnishes sufficient protection one would hardly expect to find protective coloration as well, unless indeed a creature preyed upon others, when it might be advantageous to enable a predatory animal to steal upon its prey. color often exists (or is supposed to) as a sexual characteristic, to render the male of a species attractive to, or readily recognizable by, the female, but in the case of large animals mere size is quite enough to render them conspicuous, and possibly this may be one of the factors in the dull coloration of large animals. so while a green and yellow triceratops would undoubtedly have been a conspicuous feature in the cretaceous landscape, from what we know of existing animals it seems best to curb our fancy and, so far as large dinosaurs are concerned, employ the colors of a rembrandt rather than those of a sign painter. aids, or at least hints, to the coloration of extinct animals are to be found in the coloration of the young of various living species, for as the changes undergone by the embryo are in a measure an epitome of the changes undergone by a species during its evolution, so the brief color phases or markings of the young are considered to represent the ordinary coloring of distant ancestors. young thrushes are spotted, young ostriches and grebes are irregularly striped, young lions are spotted, and in restoring the early horse, or hyracothere, professor osborn had the animal represented as faintly striped, for the reason that zebras, the wild horses of to-day, are striped, and because the ass, which is a primitive type of horse, is striped over the shoulders, these being hints that the earlier horse-like forms were also striped. thus just as the skeleton of a dinosaur may be a composite structure, made up of the bones of a dozen individuals, and these in turn mosaics of many fragments, so may the semblance of the living animal be based on a fact, pieced out with a probability and completed by a bit of theory. _references_ _there is a large series of restorations of extinct animals, prepared by mr. charles r. knight, under the direction of professor osborn, in the hall of palæontology of the american museum of natural history, and these are later to be reproduced and issued in portfolio form._ _should the reader visit princeton, he may see in the museum there a number of b. waterhouse hawkins's creations--creations is the proper word--which are of interest as examples of the early work in this line._ _the "report of the smithsonian institution for " contains an article on "the restoration of extinct animals," pages - , which includes a number of plates showing the progress that has been made in this direction._ [illustration: fig. .--a hint of buried treasures.] viii feathered giants _"there were giants in the earth in those days."_ nearly every group of animals has its giants, its species which tower above their fellows as goliath of gath stood head and shoulders above the philistine hosts; and while some of these are giants only in comparison with their fellows, belonging to families whose members are short of stature, others are sufficiently great to be called giants under any circumstances. some of these giants live to-day, some have but recently passed away, and some ceased to be long ages before man trod this earth. the most gigantic of mammals--the whales--still survive, and the elephant of to-day suffers but little in comparison with the mammoth of yesterday; the monstrous dinosaurs, greatest of all reptiles--greatest, in fact, of all animals that have walked the earth--flourished thousands upon thousands of years ago. as for birds, some of the giants among them are still living, some existed long geologic periods ago, and a few have so recently vanished from the scene that their memory still lingers amid the haze of tradition. the best known among these, as well as the most recent in point of time, are the moas of new zealand, first brought to notice by the rev. w. colenso, later on bishop of new zealand, one of the many missionaries to whom science is under obligations. early in , bishop colenso, while on a missionary visit to the east cape region, heard from the natives of waiapu tales of a monstrous bird, called moa, having the head of a man, that inhabited the mountain-side some eighty miles away. this mighty bird, the last of his race, was said to be attended by two equally huge lizards that kept guard while he slept, and on the approach of man wakened the moa, who immediately rushed upon the intruders and trampled them to death. none of the maoris had seen this bird, but they had seen and somewhat irreverently used for making parts of their fishing tackle, bones of its extinct relatives, and these bones they declared to be as large as those of an ox. about the same time another missionary, the rev. richard taylor, found a bone ascribed to the moa, and met with a very similar tradition among the natives of a near-by district, only, as the foot of the rainbow moves away as we move toward it, in his case the bird was said to dwell in quite a different locality from that given by the natives of east cape. while, however, the maoris were certain that the moa still lived, and to doubt its existence was little short of a crime, no one had actually seen it, and as time went on and the bird still remained unseen by any explorer, hope became doubt and doubt certainty, until it even became a mooted question whether such a bird had existed within the past ten centuries, to say nothing of having lived within the memory of man. but if we do not know the living birds, their remains are scattered broadcast over hillside and plain, concealed in caves, buried in the mud of swamps, and from these we gain a good idea of their size and structure, while chance has even made it possible to know something of their color and general appearance. this chance was the discovery of a few specimens, preserved in exceptionally dry caves on the south island, which not only had some of the bones still united by ligaments, but patches of skin clinging to the bones, and bearing numerous feathers of a chestnut color tipped with white. these small, straggling, rusty feathers are not much to look at, but when we reflect that they have been preserved for centuries without any care whatever, while the buffalo bugs have devoured our best smyrna rugs in spite of all possible precautions, our respect for them increases. [illustration: fig. .--relics of the moa.] from the bones we learn that there were a great many kinds of moas, twenty at least, ranging in size from those little larger than a turkey to that giant among giants, _dinornis maximus_, which stood at least ten feet high,[ ] or two feet higher than the largest ostrich, and may well claim the distinction of being the tallest of all known birds. we also learn from the bones that not only were the moas flightless, but that many of them were absolutely wingless, being devoid even of such vestiges of wings as we find in the cassowary or apteryx. but if nature deprived these birds of wings, she made ample amends in the matter of legs, those of some species, the elephant-footed moa, _pachyornis elephantopus_, for example, being so massively built as to cause one to wonder what the owner used them for, although the generally accepted theory is that they were used for scratching up the roots of ferns on which the moas are believed to have fed. and if a blow from an irate ostrich is sufficient to fell a man, what must have been the kicking power of an able-bodied moa? beside this bird the ostrich would appear as slim and graceful as a gazelle beside a prize ox. [ ] _the height of the moas, and even of some species of Æpyornis, is often stated to be twelve or fourteen feet, but such a height can only be obtained by placing the skeleton in a wholly unnatural attitude._ the moas were confined to new zealand, some species inhabiting the north island, some the south, very few being common to both, and from these peculiarities of distribution geologists deduce that at some early period in the history of the earth the two islands formed one, that later on the land subsided, leaving the islands separated by a strait, and that since this subsidence there has been sufficient time for the development of the species peculiar to each island. although moas were still numerous when man made his appearance in this part of the world, the large deposits of their bones indicate that they were on the wane, and that natural causes had already reduced the feathered population of these islands. a glacial period is believed to have wrought their destruction, and in one great morass, abounding in springs, their bones occur in such enormous numbers, layer upon layer, that it is thought the birds sought the place where the flowing springs might afford their feet at least some respite from the biting cold, and there perished miserably by thousands. what nature spared man finished, and legends of moa hunts and moa feasts still lingered among the maoris when the white man came and began in turn the extermination of the maori. the theory has been advanced, with much to support it, that the big birds were eaten off the face of the earth by an earlier race than the maoris, and that after the extirpation of the moas the craving for flesh naturally led to cannibalism. but by whomsoever the destruction was wrought, the result was the same, the habitat of these feathered giants knew them no longer, while multitudes of charred bones, interspersed with fragments of egg-shells, bear testimony to former barbaric feasts. it is a far cry from new zealand to madagascar, but thither must we go, for that island was, pity we cannot say is, inhabited by a race of giant birds from whose eggs it has been thought may have been hatched the roc of sindbad. arabian tales, as we all know, locate the roc either in madagascar or in some adjacent island to the north and east, and it is far from unlikely that legends of the Æpyornis, backed by the substantial proof of its enormous eggs, may have been the slight foundation of fact whereon the story-teller erected his structure of fiction. true, the roc of fable was a gigantic bird of prey capable of bearing away an elephant in its talons, while the Æpyornis has shed its wings and shrunk to dimensions little larger than an ostrich, but this is the inevitable result of closer acquaintance and the application of a two-foot rule. like the moa the Æpyornis seems to have lived in tradition long after it became extinct, for a french history of madagascar, published as early as makes mention of a large bird, or kind of ostrich, said to inhabit the southern end of the island. still, in spite of bones having been found that bear evident traces of the handiwork of man, it is possible that this and other reports were due to the obvious necessity of having some bird to account for the presence of the eggs. the actual introduction of the Æpyornis to science took place in , when a french traveller sent jules verreaux, the ornithologist, a sketch of a huge egg, saying that he had seen two of that size, one sawed in twain to make bowls, the other, traversed by a stick, serving in the preparation of rice uses somewhat in contrast with the proverbial fragility of egg-shells. a little later another traveller procured some fragments of egg-shells, but it was not until that any entire eggs were obtained, when two were secured, and with a few bones sent to france, where geoffroy st. hilaire bestowed upon them the name of _Æpyornis maximus_ (the greatest lofty bird). maximus the eggs remain, for they still hold the record for size; but so far as the bird that is supposed to have laid them is concerned, the name was a little premature, for other and larger species subsequently came to hand. between the Æpyornithes and the moas science has had a hard time, for the supply of big words was not large enough to go around, and some had to do duty twice. in the way of generic names we have dinornis, terrible bird; Æpyornis, high bird; pachyornis, stout bird; and brontornis, thunder bird, while for specific names there are robustus, maximus, titan; gravis, heavy; immanis, enormous; crassus, stout; ingens, great; and elephantopus, elephant-footed--truly a goodly array of large-sounding words. but to return to the big eggs! usually we look upon those of the ostrich as pretty large, but an ostrich egg measures - / by inches, while that of the Æpyornis is by inches; or, to put it another way, it would hold the contents of six ostrichs' eggs, or one hundred and forty-eight hens' eggs, or thirty thousand humming birds' eggs; and while this is very much smaller than a waterbutt, it is still as large as a bucket, and one or two such eggs might suffice to make an omelet for gargantua himself. the size of an egg is no safe criterion of the size of the bird that laid it, for a large bird may lay a small egg, or a small bird a large one. comparing the egg of the great moa with that of our Æpyornis one might think the latter much the larger bird, say twelve feet in height, when the facts in the case are that while there was no great difference in the weight of the two, that difference, and a superiority of at least two feet in height, are in favor of the bird that laid the smaller egg. the record of large eggs, however, belongs to the apteryx, a new zealand bird smaller than a hen, though distantly related to the moas, which lays an egg about one-third of its own weight, measuring by inches; perhaps it is not to be wondered at that the bird lays but two. although most of the eggs of these big birds that have been found have literally been unearthed from the muck of swamps, now and then one comes to light in a more interesting manner as, for example, when a perfect egg of Æpyornis was found afloat after a hurricane, bobbing serenely up and down with the waves near st. augustine's bay, or when an egg of the moa was exhumed from an ancient maori grave, where for years it had lain unharmed, safely clasped between the skeleton fingers of the occupant. so far very few of these huge eggs have made their way to this country, and the only egg of Æpyornis now on this side of the water is the property of a private individual. most recent in point of discovery, but oldest in point of time, are the giant birds from patagonia, which are burdened with the name of phororhacidæ, a name that originated in an error, although the error may well be excused. the first fragment of one of these great birds to come to light was a portion of the lower jaw, and this was so massive, so un-bird-like, that the finder dubbed it _phororhacos_, and so it must remain. [illustration: fig. .--eggs of feathered giants, Æpyornis, ostrich, moa, compared with a hen's egg.] it is a pity that all the large names were used up before this group of birds was discovered, and it is particularly unfortunate that dinornis, terrible bird, was applied to the root-eating moas, for these patagonian birds, with their massive limbs, huge heads and hooked beaks, were truly worthy of such a name; and although in nowise related to the eagles, they may in habit have been terrestrial birds of prey. not all the members of this family are giants, for as in other groups, some are big and some little, but the largest among them might be styled the daniel lambert of the feathered race. _brontornis_, for example, the thunder bird, or as the irreverent translate it, the thundering big bird, had leg-bones larger than those of an ox, the drumstick measuring inches in length by - / inches in diameter, or - / inches across the ends, while the tarsus, or lower bone of the leg to which the toes are attached, was - / inches long and - / inches wide where the toes join on. bear this in mind the next time you see a large turkey, or compare these bones with those of an ostrich: but lest you may forget, it may be said that the same bone of a fourteen-pound turkey is - / inches long, and one inch wide at either end, while that of an ostrich measures inches long and inches across the toes, or at the upper end. if brontornis was a heavy-limbed bird, he was not without near rivals among the moas, while the great phororhacos, one of his contemporaries, was not only nearly as large, but quite unique in build. imagine a bird seven or eight feet in height from the sole of his big, sharp-clawed feet, to the top of his huge head, poise this head on a neck as thick as that of a horse, arm it with a beak as sharp as an icepick and almost as formidable, and you have a fair idea of this feathered giant of the ancient pampas. the head indeed was truly colossal for that of a bird, measuring inches in length by in depth, while that of the racehorse lexington, and he was a good-sized horse, measures inches long by - / inches deep. the depth of the jaw is omitted because we wish to make as good a case as possible for the bird, and the jaw of a horse is so deep as to give him an undue advantage in that respect. [illustration: fig. .--skull of phororhacos compared with that of the race-horse lexington.] we can only speculate on the food of these great birds, and for aught we know to the contrary they may have caught fish, fed upon carrion, or used their powerful feet and huge beaks for grubbing roots; but if they were not more or less carnivorous, preying upon such reptiles, mammals and other birds as came within reach, then nature apparently made a mistake in giving them such a formidable equipment of beak and claw. so far as habits go we might be justified in calling them cursorial birds of prey. [illustration: fig. .--leg of a horse compared with that of the giant moa.] we really know very little about these patagonian giants, but they are interesting not only from their great size and astounding skulls, but because of the early age (miocene) at which they lived and because in spite of their bulk they are in nowise related to the ostriches, but belong near the heron family. as usual, we have no idea why they became extinct, but in this instance man is guiltless, for they lived and died long before he made his appearance, and the ever-convenient hypothesis "change of climate" may be responsible for their disappearance. something, perhaps, remains to be said concerning the causes which seem to have led to the development of these giant birds, as well as the reasons for their flightless condition and peculiar distribution, for it will be noticed that, with the exception of the african and south american ostriches the great flightless birds as a rule are, and were, confined to uninhabited or sparsely populated islands, and this is equally true of the many small, but equally flightless birds. it is a seemingly harsh law of nature that all living beings shall live in a more or less active struggle with each other and with their surroundings, and that those creatures which possess some slight advantage over their fellows in the matter of speed, or strength, or ability to adapt themselves to surrounding conditions, shall prosper at the expense of the others. in the power of flight, birds have a great safeguard against changes of climate with their accompanying variations in the supply of food, and, to a lesser extent, against their various enemies, including man. this power of flight, acquired early in their geological history, has enabled birds to spread over the length and breadth of the globe as no other group of animals has done, and to thrive under the most varying conditions, and it would seem that if this power were lost it must sooner or later work harm. now to-day we find no great wingless birds in thickly populated regions, or where beasts of prey abound; the ostriches roam the desert wastes of arabia, africa and south america where men are few and savage beasts scarce, and against these is placed a fleetness of foot inherited from ancestors who acquired it before man was. the heavy cassowaries dwell in the thinly inhabited, thickly wooded islands of malaysia, where again there are no large carnivores and where the dense vegetation is some safeguard against man; the emu comes from the australian plains, where also there are no four-footed enemies[ ] and where his ancestors dwelt in peace before the advent of man. and the same things are true of the moas, the Æpyornithes, the flightless birds of patagonia, the recent dodo of mauritius and the solitaire of rodriguez, each and all of which flourished in places where there were no men and practically no other enemies. hence we deduce that absence of enemies is the prime factor in the existence of flightless birds,[ ] although presence of food is an essential, while isolation, or restriction to a limited area, plays an important part by keeping together those birds, or that race of birds, whose members show a tendency to disuse their wings. it will be seen that such combinations of circumstances will most naturally be found on islands whose geological history is such that they have had no connection with adjacent continents, or such a very ancient connection that they were not then peopled with beasts of prey, while subsequently their distance from other countries has prevented them from receiving such population by accident in recent times and has also retarded the arrival of man. [ ] _the dingo, or native dog, is not forgotten, but, like man, it is a comparatively recent animal._ [ ] _note that in tasmania, which is very near australia, both in space and in the character of its animals, there are two carnivorous mammals, the tasmanian "wolf" and the tasmanian devil, and no flightless birds._ once established, flightlessness and size play into one another's hands; the flightless bird has no limit placed on its size[ ] while granted a food supply and immunity from man; the larger the bird the less the necessity for wings to escape from four-footed foes. so long as the climate was favorable and man absent, the big, clumsy bird might thrive, but upon the coming of man, or in the face of any unfavorable change of climate, he would be at a serious disadvantage and hence whenever either of these two factors has been brought to bear against them the feathered giants have vanished. [ ] _while we do not know the limit of size to a flying creature, none has as yet been found whose wings would spread over twenty feet from tip to tip, and it is evident that wings larger than this would demand great strength for their manipulation._ _references_ _there is a fine collection of mounted skeletons of various species of moas in the museum of comparative zoology at cambridge, mass., and another in the american museum of natural history, new york. a few _other skeletons and numerous bones are to be found in other institutions, but the author is not aware of any egg being in this country. specimens of the Æpyornis are rare in this country, but mr. robert gilfort, of orange, n.j., is the possessor of a very fine egg. a number of eggs have been sold in london, the prices ranging from £ down to £ , this last being much less than prices paid for eggs of the great auk. but then, the great auk is somewhat of a fad, and there are just enough eggs in existence to bring one into the market every little while. besides, the number of eggs of the great auk is a fixed quantity, while no one knows how many more of Æpyornis remain to be discovered in the swamps of madagascar. no specimens of the gigantic patagonian birds are now in this country, but a fine example of one of the smaller forms, pelycornis, including the only breast-bone yet found, is in the museum of princeton university._ _the largest known tibia of a moa, the longest bird-bone known, is in the collection of the canterbury museum, christchurch, new zealand; it is feet inches long. this, however, is exceptional, the measurements of the leg-bones of an ordinary dinornis maximus being as follows: femur, inches; tibia, inches; tarsus, inches, a total of feet inches. the egg measures - / by - / inches._ _there is plenty of literature, and very interesting literature, about the moas, but, unfortunately, the best of it is not always accessible, being contained in the "new zealand journal of science" and the "transactions of the new zealand institute." the volume of "transactions" for , being vol. xxvi., contains a very full list of articles relating to the moas, compiled by mr. a. hamilton; it will be found to commence on page . there is a good article on moa in newton's "dictionary of birds," a book that should be in every library._ [illustration: fig. .--the three giants, phororhacos, moa, ostrich.] ix the ancestry of the horse "_said the little eohippus i am going to be a horse and on my middle finger-nails to run my earthly course._" the american whose ancestors came over in the "mayflower" has a proper pride in the length of the line of his descent. the englishman whose genealogical tree sprang up at the time of william the conqueror has, in its eight centuries of growth, still larger occasion for pluming himself on the antiquity of his family. but the pedigree of even the latter is a thing of yesterday when compared with that of the horse, whose family records, according to professor osborn, reach backward for something like , , years. and if, as we have been told, "it is a good thing to have ancestors, but sometimes a little hard on the ancestor," in this instance at least the founders of the family have every reason to regard their descendants with undisguised pride. for the horse family started in life in a small way, and the first of the line, the hyracotherium, was "a little animal no bigger than a fox, and on five[ ] toes he scampered over tertiary rocks," in the age called eocene, because it was the morning of life for the great group of mammals whose culminating point was man. at that time, western north america was a country of many lakes, for the most part comparatively shallow, around the reedy margins of which moved a host of animals, quite unlike those of to-day, and yet foreshadowing them, the forerunners of the rhinoceros, tapir, and the horse. [ ] _four, to be exact; but we prefer to sacrifice the foot of the hyracothere rather than to take liberties with one of the feet of mrs. stetson's poem._ the early horse--we may call him so by courtesy, although he was then very far from being a true horse--was an insignificant little creature, apparently far less likely to succeed in life's race than his bulky competitors, and yet, by making the most of their opportunities, his descendants have survived, while most of theirs have dropped by the wayside; and finally, by the aid of man, the horse has become spread over the length and breadth of the habitable globe. [illustration: fig. .--skeleton of the modern horse and of his eocene ancestor.] now right here it may be asked, how do we know that the little hyracothere _was_ the progenitor of the horse, and how can it be shown that there is any bond of kinship between him and, for example, the great french percheron? there is only one way in which we can obtain this knowledge, and but one method by which the relationship can be shown, and that is by collecting the fossil remains of animals long extinct and comparing them with the bones of the recent horse, a branch of science known as palæontology. it has taken a very long time to gather the necessary evidence, and it has taken a vast amount of hard work in our western territories, for "the country that is as hot as hades, watered by stagnant alkali pools, is almost invariably the richest in fossils." likewise it has called for the expenditure of much time and more patience to put together some of this petrified evidence, fragmentary in every sense of the word, and get it into such shape that it could be handled by the anatomist. still, the work has been done, and, link by link, the chain has been constructed that unites the horse of to-day with the horse of very many yesterdays. the very first links in this chain are the remains of the bronze age and those found among the ruins of the ancient swiss lake dwellings; but earlier still than these are the bones of horses found abundantly in northern europe, asia, and america. the individual bones and teeth of some of these horses are scarcely distinguishable from those of to-day, a fact noted in the name, _equus fraternus_, applied to one species; and when teeth alone are found, it is at times practically impossible to say whether they belong to a fossil horse or to a modern animal. but when enough scattered bones are gathered to make a fairly complete skeleton, it becomes evident that the fossil horse had a proportionately larger head and smaller feet than his existing relative, and that he was a little more like an ass or zebra, for the latter, spite of his gay coat, is a near relative of the lowly ass. moreover, primitive man made sketches of the primitive horse, just as he did of the mammoth, and these indicate that the horse of those days was something like an overgrown shetland pony, low and heavily built, large-headed and rough-coated. for the old cave-dwellers of europe were intimately acquainted with the prehistoric horses, using them for food, as they did almost every animal that fell beneath their flint arrows and stone axes. and if one may judge from the abundance of bones, the horses must have roamed about in bands, just as the horses escaped from civilization roam, or have roamed, over the pampas of south america and the prairies of the west. the horse was just as abundant in north america in pleistocene time as in europe; but there is no evidence to show that it was contemporary with early man in north america, and, even were this the case, it is generally believed that long before the discovery of america the horse had disappeared. and yet, so plentiful and so fresh are his remains, and so much like those of the mustang, that the late professor cope was wont to say that it almost seemed as if the horse _might_ have lingered in texas until the coming of the white man. and sir william flower wrote: "there is a possibility of the animal having still existed, in a wild state, in some parts of the continent remote from that which was first visited by the spaniards, where they were certainly unknown. it has been suggested that the horses which were found by cabot in la plata in cannot have been introduced." still we have not the least little bit of positive proof that such was the case, and although the site of many an ancient indian village has been carefully explored, no bones of the horse have come to light, or if they have been found, bones of the ox or sheep were also present to tell that the village was occupied long after the advent of the whites. it is also a curious fact that within historic times there have been no wild horses, in the true sense of the word, unless indeed those found on the steppes north of the sea of azof be wild, and this is very doubtful. but long before the dawn of history the horse was domesticated in europe, and cæsar found the germans, and even the old britons, using war chariots drawn by horses--for the first use man seems to have made of the horse was to aid him in killing off his fellow-man, and not until comparatively modern times was the animal employed in the peaceful arts of agriculture. the immediate predecessors of these horses were considerably smaller, being about the size and build of a pony, but they were very much like a horse in structure, save that the teeth were shorter. as they lived during pliocene times, they have been named "pliohippus." going back into the past a step farther, though a pretty long step if we reckon by years, we come upon a number of animals very much like horses, save for certain cranial peculiarities and the fact that they had three toes on each foot, while the horse, as every one knows, has but one toe. now, if we glance at the skeleton of a horse, we will see on either side of the canon-bone, in the same situation as the upper part of the little toes of the hippotherium, as these three-toed horses are called, a long slender bone, termed by veterinarians the splint bone; and it requires no anatomical training to see that the bones in the two animals are the same. the horse lacks the lower part of his side toes, that is all, just as man will very probably some day lack the last bones of his little toe. we find an approach to this condition in some of the hippotheres even, known as protohippus, in which the side toes are quite small, foreshadowing the time when they shall have disappeared entirely. it may also be noted here that the splint bones of the horses of the bronze age are a little longer than those of existing horses, and that they are never united with the large central toe, while nowadays there is something of a tendency for the three bones to fuse into one, although part of this tendency the writer believes to be due to inflammation set up by the strain of the pulling and hauling the animal is now called upon to do. some of these three-toed hippotheres are not in the direct line of ancestry of the horse, but are side branches on the family tree, having become so highly specialized in certain directions that no further progress horseward was possible. backward still, and the bones we find in the miocene strata of the west, belonging to those ancestors of the horse to which the name of mesohippus has been given because they are midway in time and structure between the horse of the past and present, tell us that then all horses were small and that all had three toes on a foot, while the fore feet bore even the suggestion of a fourth toe. from this to our eocene hyracothere with four toes is only another long-time step. we may go even beyond this in time and structure, and carry back the line of the horse to animals which only remotely resembled him and had five good toes to a foot; but while these contained the possibility of a horse, they made no show of it. [illustration: fig. .--the development of the horse.] increase in size and decrease in number of the toes were not the only changes that were required to transform the progeny of the hyracothere into a horse. these are the most evident; but the increased complexity in the structure of the teeth was quite as important. the teeth of gnawing animals have often been compared to a chisel which is made of a steel plate with soft iron backing, and the teeth of a horse, or of other grass-eating animals, are simply an elaboration of this idea. the hard enamel, which represents the steel, is set in soft dentine, which represents the iron, and in use the dentine wears away the faster of the two, so that the enamel stands up in ridges, each tooth becoming, as it is correctly termed, "a grinder." in a horse the plates of enamel form curved, complex, irregular patterns; but as we go back in time, the patterns become less and less elaborate, until in the hyracothere, standing at the foot of the family tree, the teeth are very simple in structure. moreover, his teeth were of limited growth, while those of the horse grow for a considerable time, thus compensating for the wear to which they are subjected. we have, then, this direct evidence as to the genealogy of the horse, that between the little eocene hyracothere and the modern horse we can place a series of animals by which we can pass by gradual stages from one to the other, and that as we come upward there is an increase in stature, in the complexity of the teeth, and in the size of the brain. at the same time, the number of toes decreases, which tells that the animals were developing more and more speed; for it is a rule that the fewer the toes the faster the animal: the fastest of birds, the ostrich, has but two toes, and one of these is mostly ornamental; and the fastest of mammals, the horse, has but one. all breeders of fancy stock, particularly of pigeons and poultry, recognize the tendency of animals to revert to the forms whence they were derived and reproduce some character of a distant ancestor; to "throw back," as the breeders term it. if now, instead of reproducing a trait or feature possessed by some ancestor a score, a hundred, or perhaps a thousand years ago, there should reappear a characteristic of some ancestor that flourished , years back, we should have a seeming abnormality, but really a case of reversion; and the more we become acquainted with the structure of extinct animals and the development of those now living, the better able are we to explain these apparent abnormalities. bearing in mind that the two splint bones of the horse correspond to the upper portions of the side toes of the hippotherium and mesohippus, it is easy to see that if for any reason these should develop into toes, they would make the foot of a modern horse appear like that of his distant ancestor. while such a thing rarely happens, yet now and then nature apparently does attempt to reproduce a horse's foot after the ancient pattern, for occasionally we meet with a horse having, instead of the single toe with which the average horse is satisfied, one or possibly two extra toes. sometimes the toe is extra in every sense of the word, being a mere duplication of the central toe; but sometimes it is an actual development of one of the splint bones. no less a personage than julius cæsar possessed one of these polydactyl horses, and the reporters of the _daily roman_ and the _tiberian gazette_ doubtless wrote it up in good journalistic latin, for we find the horse described as having feet that were almost human, and as being looked upon with great awe. while this is the most celebrated of extra-toed horses, other and more plebeian individuals have been much more widely known through having been exhibited throughout the country under such titles as "clique, the horse with six feet," "the eight-footed cuban horse," and so on; and possibly some of these are familiar to readers of this page. so the collateral evidence, though scanty, bears out the circumstantial proof, derived from fossil bones, that the horse has developed from a many-toed ancestor; and the evidence points toward the little hyracothere as being that ancestor. it remains only to show some good reason why this development should have taken place, or to indicate the forces by which it was brought about. we have heard much about "the survival of the fittest," a phrase which simply means that those animals best adapted to their surroundings will survive, while those ill adapted will perish. but it should be added that it means also that the animals must be able to adapt themselves to changes in their environment, or to change with it. living beings cannot stand still indefinitely; they must progress or perish. and this seems to have been the cause for the extinction of the huge quadrupeds that flourished at the time of the three-toed miocene horse. they were adapted to their environment as it was; but when the western mountains were thrust upward, cutting off the moist winds from the pacific, making great changes in the rainfall and climate to the eastward of the rocky mountains, these big beasts, slow of foot and dull of brain, could not keep pace with the change, and their race vanished from the face of the earth. the day of the little hyracothere was at the beginning of the great series of changes by which the lake country of the west, with its marshy flats and rank vegetation, became transformed into dry uplands sparsely clad with fine grasses. on these dry plains the more nimble-footed animals would have the advantage in the struggle for existence; and while the four-toed foot would keep its owner from sinking in soft ground, he was handicapped when it became a question of speed, for not only is a fleet animal better able to flee from danger than his slower fellows, but in time of drouth he can cover the greater extent of territory in search of food or water. so, too, as the rank rushes gave place to fine grasses, often browned and withered beneath the summer's sun, the complex tooth had an advantage over that of simpler structure, while the cutting-teeth, so completely developed in the horse family, enabled their possessors to crop the grass as closely as one could do it with scissors. likewise, up to a certain point, the largest, most powerful animal will not only conquer, or escape from, his enemies, but prevail over rivals of his own kind as well, and thus it came to pass that those early members of the horse family who were preëminent in speed and stature, and harmonized best with their surroundings, outstripped their fellows and transmitted these qualities to their progeny, until, as a result of long ages of natural selection, there was developed the modern horse. the rest man has done: the heavy, slow-paced dray horse, the fleet trotter, the huge percheron, and the diminutive pony are one and all the recent products of artificial selection. _references_ _the best collection of fossil horses, and one specially arranged to illustrate the line of descent of the modern horse, is to be found in the american museum of natural history, new york, but some good specimens, of particular interest because they were described by professor marsh and studied by huxley are in the yale university museum. they are referred to in huxley's "american addresses; lectures on evolution." "the horse," by sir w. h. flower, discusses the horse in a popular manner from various points of view and contains numerous references to books and articles on the subject from which anyone wishing for further information could obtain it._ [illustration: fig. .--the mammoth. _from a drawing by charles r. knight._] x the mammoth "_his legs were as thick as the bole of the beech, his tusks as the buttonwood white, while his lithe trunk wound like a sapling around an oak in the whirlwind's might._" _in the october number of mcclure's magazine for was published a short story, "the killing of the mammoth," by "h. tukeman," which, to the amazement of the editors, was taken by many readers not as fiction, but as a contribution to natural history. immediately after the appearance of that number of the magazine, the authorities of the smithsonian institution, in which the author had located the remains of the beast of his fancy, were beset with visitors to see the stuffed mammoth, and the daily mail of the magazine, as well as that of the smithsonian institution, was filled with inquiries for more information and for requests to settle wagers as to whether it was a true story or not. the contribution in question was printed purely as fiction, with no idea of misleading the public, and was entitled a story in the table of contents. we doubt if any writer of realistic fiction ever had a more general and convincing proof of success._ about three centuries ago, in , a russian, one ludloff by name, described some bones belonging to what the tartars called "mamantu"; later on, blumenbach pressed the common name into scientific use as "mammut," and cuvier gallicized this into "mammouth," whence by an easy transition we get our familiar mammoth. we are so accustomed to use the word to describe anything of remarkable size that it would be only natural to suppose that the name mammoth was given to the extinct elephant because of its extraordinary bulk. exactly the reverse of this is true, however, for the word came to have its present meaning because the original possessor of the name was a huge animal. the siberian peasants called the creature "mamantu," or "ground-dweller," because they believed it to be a gigantic mole, passing its life beneath the ground and perishing when by any accident it saw the light. the reasoning that led to this belief was very simple and the logic very good; no one had ever seen a live mamantu, but there were plenty of its bones lying at or near the surface; consequently if the animal did not live above the ground, it must dwell below. to-day, nearly every one knows that the mammoth was a sort of big, hairy elephant, now extinct, and nearly every one has a general idea that it lived in the north. there is some uncertainty as to whether the mammoth was a mastodon, or the mastodon a mammoth, and there is a great deal of misconception as to the size and abundance of this big beast. it may be said in passing that the mastodon is only a second or third cousin of the mammoth, but that the existing elephant of asia is a very near relative, certainly as near as a first cousin, possibly a very great grandson. popularly, the mammoth is supposed to have been a colossus somewhere from twelve to twenty feet in height, beside whom modern elephants would seem insignificant; but as "trout lose much in dressing," so mammoths shrink in measuring, and while there were doubtless jumbos among them in the way of individuals of exceptional magnitude, the majority were decidedly under jumbo's size. the only mounted mammoth skeleton in this country, that in the chicago academy of sciences, is one of the largest, the thigh-bone measuring five feet one inch in length, or a foot more than that of jumbo; and as jumbo stood eleven feet high, the rule of three applied to this thigh-bone would give the living animal a height of thirteen feet eight inches. the height of this specimen is given as thirteen feet in its bones, with an estimate of fourteen feet in its clothes; but as the skeleton is obviously mounted altogether too high, it is pretty safe to say that thirteen feet is a good, fair allowance for the height of this animal when alive. as for the majority of mammoths, they would not average more than nine or ten feet high. sir samuel baker tells us that he has seen plenty of wild african elephants that would exceed jumbo by a foot or more, and while this must be accepted with caution, since unfortunately he neglected to put a tape-line on them, yet mr. thomas baines did measure a specimen twelve feet high. this, coupled with sir samuel's statement, indicates that there is not so much difference between the mammoth and the elephant as there might be. this applies to the mammoth _par excellence_, the species known scientifically as _elephas primigenius_, whose remains are found in many parts of the northern hemisphere and occur abundantly in siberia and alaska. there were other elephants than the mammoth, and some that exceeded him in size, notably _elephas meridionalis_ of southern europe, and _elephas columbi_ of our southern and western states, but even the largest cannot positively be asserted to have exceeded a height of thirteen feet. tusks offer convenient terms of comparison, and those of an average fully grown mammoth are from eight to ten feet in length; those of the famous st. petersburg specimen and those of the huge specimen in chicago measuring respectively nine feet three inches, and nine feet eight inches. so far as the writer is aware, the largest tusks actually measured are two from alaska, one twelve feet ten inches long, weighing pounds, reported by mr. jay beach; and another eleven feet long, weighing pounds, noted by mr. t. l. brevig. compared with these we have the big tusk that used to stand on fulton street, new york, just an inch under nine feet long, and weighing pounds, or the largest shown at chicago in , which was seven feet six inches long, and weighed pounds. the largest, most beautiful tusks, probably, ever seen in this country were a pair brought from zanzibar and displayed by messrs. tiffany & company in . the measurements and weights of these were as follows: length along outer curve, ten feet and three-fourths of an inch, circumference one foot, eleven inches, weight, pounds; length along outer curve, ten feet, three and one-half inches, circumference two feet and one-fourth of an inch, weight, pounds. for our knowledge of the external appearance of the mammoth we are indebted to the more or less entire examples which have been found at various times in siberia, but mainly to the noted specimen found in near the lena, embedded in the ice, where it had been reposing, so geologists tell us, anywhere from , to , years. how the creature gradually thawed out of its icy tomb, and the tusks were taken by the discoverer and sold for ivory; how the dogs fed upon the flesh in summer, while bears and wolves feasted upon it in winter; how the animal was within an ace of being utterly lost to science when, at the last moment, the mutilated remains were rescued by mr. adams, is an old story, often told and retold. suffice it to say that, besides the bones, enough of the beast was preserved to tell us exactly what was the covering of this ancient elephant, and to show that it was a creature adapted to withstand the northern cold and fitted for living on the branches of the birch and hemlock. [illustration: fig. .--skeleton of the mammoth in the royal museum of st. petersburg.] the exact birthplace of the mammoth is as uncertain as that of many other great characters; but his earliest known resting-place is in the cromer forest beds of england, a country inhabited by him at a time when the german ocean was dry land and great britain part of a peninsula. here his remains are found to-day, while from the depths of the north sea the hardy trawlers have dredged hundreds, aye thousands, of mammoth teeth in company with soles and turbot. if, then, the mammoth originated in western europe, and not in that great graveyard of fossil elephants, northern india, eastward he went spreading over all europe north of the pyrenees and alps, save only scandinavia, whose glaciers offered no attractions, scattering his bones abundantly by the wayside to serve as marvels for future ages. strange indeed have been some of the tales to which these and other elephantine remains have given rise when they came to light in the good old days when knowledge of anatomy was small and credulity was great. the least absurd theory concerning them was that they were the bones of the elephants which hannibal brought from africa. occasionally they were brought forward as irrefutable evidences of the deluge; but usually they figured as the bones of giants, the most famous of them being known as teutobochus, king of the cimbri, a lusty warrior said to have had a height of nineteen feet. somewhat smaller, but still of respectable height, fourteen feet, was "littell johne" of scotland, whereof hector boece wrote, concluding, in a moralizing tone, "be quilk (which) it appears how extravegant and squaire pepill grew in oure regioun afore they were effeminat with lust and intemperance of mouth." more than this, these bones have been venerated in greece and rome as the remains of pagan heroes, and later on worshipped as relics of christian saints. did not the church of valencia possess an elephant tooth which did duty as that of st. christopher, and, so late as , was not a thigh-bone, figuring as the arm-bone of a saint, carried in procession through the streets in order to bring rain? out of europe eastward into asia the mammoth took his way, and having peopled that vast region, took advantage of a land connection then existing between asia and north america and walked over into alaska, in company with the forerunners of the bison and the ancestors of the mountain sheep and alaskan brown bear. still eastward and southward he went, until he came to the atlantic coast, the latitude of southern new york roughly marking the southern boundary of the broad domain over which the mammoth roamed undisturbed.[ ] not that of necessity all this vast area was occupied at one time; but this was the range of the mammoth during pleistocene time, for over all this region his bones and teeth are found in greater or less abundance and in varying conditions of preservation. in regions like parts of siberia and alaska, where the bones are entombed in a wet and cold, often icy, soil, the bones and tusks are almost as perfectly preserved as though they had been deposited but a score of years ago, while remains so situated that they have been subjected to varying conditions of dryness and moisture are always in a fragmentary state. as previously noted, several more or less entire carcasses of the mammoth have been discovered in siberia, only to be lost; and, while no entire animal has so far been found in alaska, some day one may yet come to light. that there is some possibility of this is shown by the discovery, recorded by mr. dall, of the partial skeleton of a mammoth in the bank of the yukon with some of the fat still present, and although this had been partially converted into adipocere, it was fresh enough to be used by the natives for greasing, not their boots, but their boats. and up to the present time this is the nearest approach to finding a live mammoth in alaska. [ ] _this must be taken as a very general statement, as the distinction between and habitats of elephas primigenius and elephas columbi, the southern mammoth, are not satisfactorily determined; moreover, the two species overlap through a wide area of the west and northwest._ as to why the mammoth became extinct, we _know_ absolutely nothing, although various theories, some much more ingenious than plausible, have been advanced to account for their extermination--they perished of starvation; they were overtaken by floods on their supposed migrations and drowned in detachments; they fell through the ice, equally in detachments, and were swept out to sea. but all we can safely say is that long ages ago the last one perished off the face of the earth. strange it is, too, that these mighty beasts, whose bulk was ample to protect them against four-footed foes, and whose woolly coat was proof against the cold, should have utterly vanished. they ranged from england eastward to new york, almost around the world; from the alps to the arctic ocean; and in such numbers that to-day their tusks are articles of commerce, and fossil ivory has its price current as well as wheat. mr. boyd dawkins thinks that the mammoth was actually exterminated by early man, but, even granting that this might be true for southern and western europe, it could not be true of the herds that inhabited the wastes of siberia, or of the thousands that flourished in alaska and the western united states. so far as man is concerned, the mammoth might still be living in these localities, where, before the discovery of gold drew thousands of miners to alaska, there were vast stretches of wilderness wholly untrodden by the foot of man. neither could this theory account for the disappearance of the mastodon from north america, where that animal covered so vast a stretch of territory that man, unaided by nature, could have made little impression on its numbers. that many were swept out to sea by the flooded rivers of siberia is certain, for some of the low islands off the coast are said to be formed of sand, ice, and bones of the mammoth, and thence, for hundreds of years, have come the tusks which are sold in the market beside those of the african and indian elephants. that man was contemporary with the mammoth in southern europe is fairly certain, for not only are the remains of the mammoth and man's flint weapons found together, but in a few instances some primeval landseer graved on slate, ivory, or reindeer antler a sketchy outline of the beast, somewhat impressionistic perhaps, but still, like the work of a true artist, preserving the salient features. we see the curved tusks, the snaky trunk, and the shaggy coat that we know belonged to the mammoth, and we may feel assured that if early man did not conquer the clumsy creature with fire and flint, he yet gazed upon him from the safe vantage point of some lofty tree or inaccessible rock, and then went home to tell his wife and neighbors how the animal escaped because his bow missed fire. that man and mammoth lived together in north america is uncertain; so far there is no evidence to show that they did, although the absence of such evidence is no proof that they did not. that any live mammoth has for centuries been seen on the alaskan tundras is utterly improbable, and on mr. c. h. townsend seems to rest the responsibility of having, though quite unintentionally, introduced the alaskan live mammoth into the columns of the daily press. it befell in this wise: among the varied duties of our revenue marine is that of patrolling and exploring the shores of arctic alaska and the waters of the adjoining sea, and it is not so many years ago that the cutter _corwin_, if memory serves aright, held the record of farthest north on the pacific side. on one of these northern trips, to the kotzebue sound region, famous for the abundance of its deposits of mammoth bones,[ ] the _corwin_ carried mr. townsend, then naturalist to the united states fish commission. at cape prince of wales some natives came on board bringing a few bones and tusks of the mammoth, and upon being questioned as to whether or not any of the animals to which they pertained were living, promptly replied that all were dead, inquiring in turn if the white men had ever seen any, and if they knew how these animals, so vastly larger than a reindeer, looked. [ ] _elephant point, at the mouth of the buckland river, is so named from the numbers of mammoth bones which have accumulated there._ fortunately, or unfortunately, there was on board a text-book of geology containing the well-known cut of the st. petersburg mammoth, and this was brought forth, greatly to the edification of the natives, who were delighted at recognizing the curved tusks and the bones they knew so well. next the natives wished to know what the outside of the creature looked like, and as mr. townsend had been at ward's establishment in rochester when the first copy of the stuttgart restoration was made, he rose to the emergency, and made a sketch. this was taken ashore, together with a copy of the cut of the skeleton that was laboriously made by an innuit sprawled out at full length on the deck. now the innuits, as mr. townsend tells us, are great gadabouts, making long sledge journeys in winter and equally long trips by boat in summer, while each season they hold a regular fair on kotzebue sound, where a thousand or two natives gather to barter and gossip. on these journeys and at these gatherings the sketches were no doubt passed about, copied, and recopied, until a large number of innuits had become well acquainted with the appearance of the mammoth, a knowledge that naturally they were well pleased to display to any white visitors. also, like the celt, the alaskan native delights to give a "soft answer," and is always ready to furnish the kind of information desired. thus in due time the newspaper man learned that the alaskans could make pictures of the mammoth, and that they had some knowledge of its size and habits; so with inference and logic quite as good as that of the tungusian peasant, the reporter came to the conclusion that somewhere in the frozen wilderness the last survivor of the mammoths must still be at large. and so, starting on the pacific coast, the live mammoth story wandered from paper to paper, until it had spread throughout the length and breadth of the united states, when it was captured by mr. tukeman, who with much artistic color and some realistic touches, transferred it to _mcclure's magazine_, and--unfortunately for the officials thereof--to the smithsonian institution. and now, once for all, it may be said that _there is no mounted mammoth_ to awe the visitor to the national collections or to any other; and yet there seems no good and conclusive reason why there should not be. true, there are no live mammoths to be had at any price; neither are their carcasses to be had on demand; still there is good reason to believe that a much smaller sum than that said to have been paid by mr. conradi for the mammoth which is _not_ in the smithsonian institution, would place one there.[ ] it probably could not be done in one year; it might not be possible in five years; but should any man of means wish to secure enduring fame by showing the world the mammoth as it stood in life, a hundred centuries ago, before the dawn of even tradition, he could probably accomplish the result by the expenditure of a far less sum than it would cost to participate in an international yacht race. [ ] _since these lines were written another fine example of the mammoth has been discovered in siberia and even now (oct., ) an expedition is on its way to secure the skin and skeleton for the academy of natural sciences at st. petersburg._ _references_ _the mounted skeleton of the mammoth in the museum of the chicago academy of science is still the only one on exhibition in the united states; this specimen is probably the southern mammoth, elephas columbi, a species, or race, characterized by its great size and the coarse structure of the teeth. remains of the mammoth are common enough but, save in alaska, they are usually in a poor state of preservation or consist of isolated bones or teeth. a great many skeletons of mammoth have been found by gold miners in alaska, and with proper care some of these could undoubtedly have been secured. naturally, however, the miners do not feel like taking the time and trouble to exhume bones whose value is uncertain, while the cost of transportation precludes the bringing out of many specimens._ _some reports of mammoths have been based on the bones of whales, including a skull that was figured in the daily papers._ _almost every museum has on exhibition teeth of the mammoth, and there is a skull, though from a small individual, of the southern mammoth in the american museum of natural history, new york._ _the tusk obtained by mr. beach and mentioned in the text still holds the record for mammoth tusks. the greatest development of tusks occurred in elephas ganesa, a species found in pliocene deposits of the siwalik hills, india. this species appears not to have exceeded the existing elephant in bulk, but the tusks are twelve feet nine inches long, and two feet two inches in circumference. how the animal ever carried them is a mystery, both on account of their size and their enormous leverage. as for teeth, an upper grinder of elephas columbi in the united states national museum is ten and one-half inches high, nine inches wide, the grinding face being eight by five inches. this tooth, which is unusually perfect, retaining the outer covering of cement, came from afton, indian territory, and weighs a little over fifteen pounds. the lower tooth, shown in fig. , is twelve inches long, and the grinding face is nine by three and one-half inches; this is also from elephas columbi. grinders of the northern mammoth are smaller, and the plates of enamel thinner, and closer to one another. mr. f. e. andrews, of gunsight, texas, reports having found a femur, or thigh-bone five feet four inches long, and a humerus measuring four feet three inches, these being the largest bones on record indicating an animal fourteen feet high._ _there is a vast amount of literature relating to the mammoth, some of it very untrustworthy. a list of all discoveries of specimens in the flesh is given by nordenskiold in "the voyage of the vega" and "the mammoth and the flood" by sir henry howorth, is a mine of information. mr. townsend's "alaska live-mammoth story" may be found in "forest and stream" for august , ._ [illustration: fig. .--the mammoth as engraved by a primitive artist on a piece of mammoth tusk.] xi the mastodon "_... who shall place a limit to the giant's unchained strength?_" the name mastodon is given to a number of species of fossil elephants differing from the true elephants, of which the mammoth is an example, in the structure of the teeth. in the mastodons the crown, or grinding face of the tooth, is formed by more or less regular /\-shaped cross ridges, covered with enamel, while in the elephants the enamel takes the form of narrow, pocket-shaped plates, set upright in the body of the tooth. moreover, in the mastodons the roots of the teeth are long prongs, while in the elephants the roots are small and irregular. a glance at the cuts will show these distinctions better than they can be explained by words. back in the past, however, we meet, as we should if there is any truth in the theory of evolution, with elephants having an intermediate pattern of teeth. [illustration: fig. .--tooth of mastodon and of mammoth.] there is usually, or at least often, another point of difference between elephants and mastodons, for many of the latter not only had tusks in the upper, but in the lower jaw, and these are never found in any of the true elephants. the lower tusks are longer and larger in the earlier species of mastodon than in those of more recent age and in the latest species, the common american mastodon, the little lower tusks were usually shed early in life. these afford some hints of the relationships of the mastodon; for in europe are found remains of a huge beast well called dinotherium, or terrible animal, which possessed lower tusks only, and these, instead of sticking out from the jaw are bent directly downwards. no perfect skull of this creature has yet been found, but it is believed to have had a short trunk. for a long time nothing but the skull was known, and some naturalists thought the animal to have been a gigantic manatee, or sea cow, and that the tusks were used for tearing food from the bottom of rivers and for anchoring the animal to the bank, just as the walrus uses his tusks for digging clams and climbing out upon the ice. in the first restorations of dinotherium it is represented lying amidst reeds, the feet concealed from view, the head alone visible, but now it is pictured as standing erect, for the discovery of massive leg-bones has definitely settled the question as to whether it did or did not have limbs. there is another hint of relationship in the upper tusks of the earlier mastodons, and this is the presence of a band of enamel running down each tusk. in all gnawing animals the front, cutting teeth are formed of soft dentine, or ivory, faced with a plate of enamel, just as the blade of a chisel or plane is formed of a plate of tempered steel backed with soft iron; the object of this being the same in both tooth and chisel, to keep the edge sharp by wearing away the softer material. in the case of the chisel this is done by a man with a grindstone, but with the tooth it is performed automatically and more pleasantly by the gnawing of food. in the mastodon and elephant the tusks, which are the representatives of the cutting teeth of rodents, are wide apart, and of course do not gnaw anything, but the presence of these enamel bands hints at a time when they and their owner were smaller and differently shaped, and the teeth were used for cutting. thus, great though the disparity of size may be, there is a suggestion that through the mastodon the elephant is distantly related to the mouse, and that, could we trace their respective pedigrees far enough, we might find a common ancestor. this presence of structures that are apparently of no use, often worse than useless, is regarded as the survival of characters that once served some good purpose, like the familiar buttons on the sleeve or at the back of a man's coat, or the bows and ruffles on a woman's dress. we are told that these are put on "to make the dress look pretty," but the student regards the bows as vestiges of the time when there were no buttons and hooks and eyes had not been invented, and dresses were tied together with strings or ribbons. as for ruffles, they took the place of flounces, and flounces are vestiges of the time when a young woman wore the greater part of her wardrobe on her back, putting on one dress above another, the bottoms of the skirts showing like so many flounces. so buttons, ruffles, and the vermiform appendix of which we hear so much all fall in the category of vestigial structures. where the mastodons originated, we know not: señor ameghino thinks their ancestors are to be found in patagonia, and he is very probably wrong; professor cope thought they came from asia, and he is probably right; or they may have immigrated from the convenient antarctica, which is called up to account for various facts in the distribution of animals.[ ] [ ] _during the past year, , mr. c. w. andrews of the british museum has discovered in egypt a small and primitive species of mastodon, also the remains of another animal which he thinks may be the long sought ancestor of the elephant family, which includes the mammoth and mastodon._ neither do we at present know just how many species of mastodons there may have been in the western hemisphere, for most of them are known from scattered teeth, single jaws, and odd bones, so that we cannot tell just what differences may be due to sex or individual variation. it is certain, however, that several distinct kinds, or species, have inhabited various parts of north america, while remains of others occur in south america. _the_ mastodon, however, the one most recent in point of time, and the best known because its remains are scattered far and wide over pretty much the length and breadth of the united states, and are found also in southern and western canada, is the well-named _mastodon americanus_,[ ] and unless otherwise specified this alone will be meant when the name mastodon is used. in some localities the mastodon seems to have abounded, but between the hudson and connecticut rivers indications of its former presence are rare, and east of that they are practically wanting. the best preserved specimens come from ulster and orange counties, new york, for these seem to have furnished the animal with the best facilities for getting mired. just west of the catskills, parallel with the valley of the hudson, is a series of meadows, bogs, and pools marking the sites of swamps that came into existence after the recession of the mighty ice-sheet that long covered eastern north america, and in these many a mastodon, seeking for food or water, or merely wallowing in the mud, stuck fast and perished miserably. and here to-day the spade of the farmer as he sinks a ditch to drain what is left of some beaver pond of bygone days, strikes some bone as brown and rugged as a root, so like a piece of water-soaked wood that nine times out of ten it is taken for a fragment of tree-trunk. [ ] _this has also been called giganteus and ohioticus, but the name americanus claims priority, and should therefore be used._ the first notice of the mastodon in north america goes back to , and is found in a letter from cotton mather to dr. woodward (of england?) written at boston on november th, in which he speaks of a large work in manuscript entitled _biblia americana_, and gives as a sample a note on the passage in genesis (vi. ) in which we read that "there were giants in the earth in those days." we are told that this is confirmed by "the bones and teeth of some large animal found lately in albany, in new england, which for some reason he thinks to be human; particularly a tooth brought from the place where it was found to new york in , being a very large grinder, weighing four pounds and three quarters; with a bone supposed to be a thigh-bone, seventeen feet long," the total length of the body being taken as seventy-five feet. thus bones of the mastodon, as well as those of the mammoth, have done duty as those of giants. and as the first mastodon remains recorded from north america came from the region west of the hudson, so the first fairly complete skeleton also came from that locality, secured at a very considerable outlay of money and a still more considerable expenditure of labor by the exertions of c. w. peale. this specimen was described at some length by rembrandt peale in a privately printed pamphlet, now unfortunately rare, and described in some respects better than has been done by any subsequent writer, since the points of difference between various parts of the mastodon and elephant were clearly pointed out. this skeleton was exhibited in london, and afterwards at peale's museum in philadelphia where, with much other valuable material, it was destroyed by fire. struck by the evident crushing power of the great ridged molars, peale was led to believe that the mastodon was a creature of carnivorous habits, and so described it, but this error is excusable, the more that to this day, when the mastodon is well known, and its description published time and again in the daily papers, finders of the teeth often consider them as belonging to some huge beast of prey. since the time of peale several fine specimens have been taken from ulster and orange counties, among them the well-known "warren mastodon," and there is not the slightest doubt that many more will be recovered from the meadows, swamps, and pond holes of these two counties. [illustration: fig. .--the missourium of koch, from a tracing of the figure illustrating koch's description.] the next mastodon to appear on the scene was the so-called missourium of albert koch, which he constructed somewhat as he did the hydrarchus (see p. ) of several individuals pieced together, thus forming a skeleton that was a monster in more ways than one. to heighten the effect, the curved tusks were so placed that they stood out at right angles to the sides of the head, like the swords upon the axles of ancient war chariots. like peale's specimen this was exhibited in london, and there it still remains, for, stripped of its superfluous bones, and remounted, it may now be seen in the british museum. many a mastodon has come to light since the time of koch, for while it is commonly supposed that remains of the animal are great rarities, as a matter of fact they are quite common, and it may safely be said that during the seasons of ditching, draining, and well-digging not a week passes without one or more mastodons being unearthed. not that these are complete skeletons, very far from it, the majority of finds are scattered teeth, crumbling tusks, or massive leg-bones, but still the mastodon is far commoner in the museums of this country than is the african elephant, for at the present date there are eleven of the former to one of the latter, the single skeleton of african elephant being that of jumbo in the american museum of natural history. if one may judge by the abundance of bones, mastodons must have been very numerous in some favored localities such as parts of michigan, florida, and missouri and about big bone lick, ky. perhaps the most noteworthy of all deposits is that at kimmswick, about twenty miles south of st. louis, where in a limited area mr. l. w. beehler has exhumed bones representing several hundred individuals, varying in size from a mere baby mastodon up to the great tusker whose wornout teeth proclaim that he had reached the limit of even mastodonic old age. the spot where this remarkable deposit was found is at the foot of a bluff near the junction of two little streams, and it seems probable that in the days when these were larger the spring floods swept down the bodies of animals that had perished during the winter to ground in an eddy beneath the bluff. or as the place abounds in springs of sulphur and salt water it may be that this was where the animals assembled during cold weather, just as the moas are believed to have gathered in the swamps of new zealand, and here the weaker died and left their bones. the mastodon must have looked very much like any other elephant, though a little shorter in the legs and somewhat more heavily built than either of the living species, while the head was a trifle flatter and the jaw decidedly longer. the tusks are a variable quantity, sometimes merely bowing outwards, often curving upwards to form a half circle; they were never so long as the largest mammoth tusks, but to make up for this they were a shade stouter for their length. as the mastodon ranged well to the north it is fair to suppose that he may have been covered with long hair, a supposition that seems to be borne out by the discovery, noted by rembrandt peale, of a mass of long, coarse, woolly hair buried in one of the swamps of ulster county, new york. and with these facts in mind, aided by photographs of various skeletons of mastodons, mr. gleeson made the restoration which accompanies this chapter. [illustration: fig. .--the mastodon. _from a drawing by j. m. gleeson._] as for the size of the mastodon, this, like that of the mammoth, is popularly much over-estimated, and it is more than doubtful if any attained the height of a full-grown african elephant. the largest femur, or thigh-bone, that has come under the writer's notice was one he measured as it lay in the earth at kimmswick, and this was just four feet long, three inches shorter than the thigh-bone of jumbo. several of the largest thigh-bones measured show so striking an unanimity in size, between and inches in length, that we may be pretty sure they represent the average old "bull" mastodon, and if we say that these animals stood ten feet high we are probably doing them full justice. an occasional tusk reaches a length of ten feet, but seven or eight is the usual size, with a diameter of as many inches, and this is no larger than the tusks of the african elephant would grow if they had a chance. it is painful to be obliged to scale down the mastodon as we have just done the mammoth, but if any reader knows of specimens larger than those noted, he should by all means publish their measurements.[ ] [ ] _as skeletons are sometimes mounted, they stand a full foot or more higher at the shoulders than the animal stood in life, this being caused by raising the body until the shoulder-blades are far below the tips of the vertebræ, a position they never assume in life._ the disappearance of the mastodon is as difficult to account for as that of the mammoth, and, as will be noted, there is absolutely no evidence to show that man had any hand in it. neither can it be ascribed to change of climate, for the mastodon, as indicated by the wide distribution of its bones, was apparently adapted to a great diversity of climates, and was as much at home amid the cool swamps of michigan and new york as on the warm savannas of florida and louisiana. certainly the much used, and abused, glacial epoch cannot be held accountable for the extermination of the creature, for the mastodon came into new york after the recession of the great ice-sheet, and tarried to so late a date that bones buried in the swamps retain much of their animal matter. so recent, comparatively speaking, has been the disappearance of the mastodon, and so fresh-looking are some of its bones, that thomas jefferson thought in his day that it might still be living in some part of the then unexplored northwest. it is a moot question whether or not man and the mastodon were contemporaries in north america, and while many there be who, like the writer of these lines, believe that this was the case, an expression of belief is not a demonstration of fact. the best that can be said is that there are scattered bits of testimony, slight though they are, which seem to point that way, but no one so strong by itself that it could not be shaken by sharp cross-questioning and enable man to prove an alibi in a trial by jury. for example, in the great bone deposit at kimmswick, mo., mr. beehler found a flint arrowhead, but this may have lain just over the bone-bearing layer, or have got in by some accident in excavating. how easily a mistake may be made is shown by the report sent to the united states national museum of many arrowheads associated with mastodon bones in a spring at afton, indian territory. this spring was investigated, and a few mastodon bones and flint arrowheads were found, but the latter were in a stratum just above the bones, although this was overlooked by the first diggers.[ ] koch reported finding charcoal and arrowheads so associated with mastodon bones that he inferred the animal to have been destroyed by fire and arrows after it became mired. it has been said that koch could have had no object in disseminating this report, and hence that it may be credited, but he had just as much interest in doing this as he did in fabricating the hydrarchus and the missourium, and his testimony is not to be considered seriously. it seems to be with the mastodon much as it is with the sea-serpent; the latter never appears to a naturalist, remains of the former are never found by a trained observer associated with indications of the presence of man. perhaps an exception should be made in the case of professor j. m. clarke, who found fragments of charcoal in a deposit of muck under some bones of mastodon. [ ] _this locality has just been carefully investigated by mr. w. h. holmes of the united states national museum who found bones of the mastodon and southern mammoth associated with arrowheads. but he also found fresh bones of bison, horse, and wolf, showing that these and the arrowheads had simply sunk to the level of the older deposit._ we may pass by the so-called "elephant mound," which to the eye of an unimaginative observer looks as if it might have been intended for any one of several beasts; also, with bated breath and due respect for the bitter controversy waged over them, pass we by the elephant pipes. there remains, then, not a bit of man's handiwork, not a piece of pottery, engraved stone, or scratched bone that can _unhesitatingly_ be said to have been wrought into the shape of an elephant before the coming of the white man. true, there is "the lenape stone," found near doyleston, pa., in , a gorget graven on one side with the representation of men attacking an elephant, while the other bears a number of figures of various animals. the good faith of the finder of this stone is unimpeachable, but it is a curious fact that, while this gorget is elaborately decorated on both sides, no similar stone, out of all that have been found, bears any image whatsoever. on the other hand, if not made by the aborigines, who made it, why was it made, and why did nine years elapse between the discovery of the first and second portions of the broken ornament? these are questions the reader may decide for himself; the author will only say that to his mind the drawing is too elaborate, and depicts entirely too much to have been made by a primitive artist. a much better bit of testimony seems to be presented by a fragment of fulgur shell found near hollyoak, del., and now in the united states national museum, which bears a very rudely scratched image of an animal that may have been intended for a mastodon or a bison. this piece of shell is undeniably old, but there is, unfortunately, the uncertainty just mentioned as to the animal depicted. the familiar legend of the big buffalo that destroyed animals and men and defied even the lightnings of the great spirit has been thought by some to have originated in a tradition of the mastodon handed down from ancient times; but why consider that the mastodon is meant? why not a legendary bison that has increased with years of story-telling? and so the co-existence of man and mastodon must rest as a case of not proven, although there is a strong probability that the two did live together in the dim ages of the past, and some day the evidence may come to light that will prove it beyond a peradventure. if scientific men are charged with obstinacy and unwarranted incredulity in declining to accept the testimony so far presented, it must be remembered that the evidence as to the existence of the sea serpent is far stronger, since it rests on the testimony of eye-witnesses, and yet the creature himself has never been seen by a trained observer, nor has any specimen, not a scale, a tooth, or a bone, ever made its way into any museum. _references_ _there are at least eleven mounted skeletons of the mastodon in the united states, and the writer trusts he may be pardoned for mentioning only those which are most accessible. these are in the american museum of natural history, new york; the state museum, albany, n. y.; field columbian museum, chicago; carnegie museum, pittsburg; museum of comparative zoölogy, cambridge, mass. there is no mounted skeleton in the united states national museum, nor has there ever been._ _the heaviest pair of tusks is in the possession of t. o. tuttle, seneca, mich., and they are nine and one-half inches in diameter, and a little over eight feet long; very few tusks, however, reach eight inches in diameter. the thigh-bone of an old male mastodon measures from forty-five to forty-six and one-half inches long, the humerus from thirty-five to forty inches. the height of the mounted skeleton is of little value as an indication of size, since it depends so much upon the manner in which the skeleton is mounted. the grinders of the mastodon have three cross ridges, save the last, which has four, and a final elevation, or heel. this does not apply to the teeth of very young animals. the presence or absence of the last grinder will show whether or not the animal is of full age and size, while the amount of wear indicates the comparative age of the specimen._ _the skeleton of the "warren mastodon" is described at length by dr. j. c. warren, in a quarto volume entitled "mastodon giganteus." there is much information in a little book by j. p. maclean, "mastodon, mammoth, and man," but the reader must not accept all its statements unhesitatingly. the first volume, , of the new scribner's magazine contains an article on "american elephant myths," by professor w. b. scott, but he is under an erroneous impression regarding the size of the mastodon, and photographs of the maya carvings show that their resemblance to elephants has been exaggerated in the wood cuts. the story of the lenape stone is told at length by h. c. mercer in "the lenape stone, or the indian and the mammoth."_ [illustration: fig. .--the lenape stone, reduced.] xii why do animals become extinct? "_and sultan after sultan with his pomp abode his destined hour and went his way._" it is often asked "why do animals become extinct?" but the question is one to which it is impossible to give a comprehensive and satisfactory reply; this chapter does not pretend to do so, merely to present a few aspects of this complicated, many-sided problem. in very many cases it may be said that actual extermination has not taken place, but that in the course of evolution one species has passed into another; species may have been lost, but the race, or phylum endures, just as in the growth of a tree, the twigs and branches of the sapling disappear, while the tree, as a whole, grows onward and upward. this is what we see in the horse, which is the living representative of an unbroken line reaching back to the little eocene hyracothere. so in a general way it may be said that much of what at the first glance we might term extinction is really the replacement of one set of animals by another better adapted to surrounding conditions. again, there are many cases of animals, and particularly of large animals, so peculiar in their make up, so very obviously adapted to their own special surroundings that it requires little imagination to see that it would have been a difficult matter for them to have responded to even a slight change in the world about them. such great and necessarily sluggish brutes as brontosaurus and diplodocus, with their tons of flesh, small heads, and feeble teeth, were obviously reared in easy circumstances, and unfitted to succeed in any strenuous struggle for existence. stegosaurus, with his bizarre array of plates and spines, and huge-headed triceratops, had evidently carried specialization to an extreme, while in turn the carnivorous forms must have required an abundant supply of slow and easily captured prey. coming down to a more recent epoch, when the big titanotheres flourished, it is easy to see from a glance at their large, simple teeth that these beasts needed an ample provision of coarse vegetation, and as they seem never to have spread far beyond their birthplace, climatic change, modifying even a comparatively limited area, would suffice to sweep them out of existence. to use the epitaph proposed by professor marsh for the tombstone of one of the dinosaurs, many a beast might say, "i, and my race perished of over specialization." to revert to the horse it will be remembered that this very fate is believed to have overtaken those almost horses the european hippotheres; they reached a point where no further progress was possible, and fell by the wayside. there is, however, still another class of cases where species, families, orders, even, seem to have passed out of existence without sufficient cause. those great marine reptiles, the ichthyosaurs, of europe, the plesiosaurs and mosasaurs, of our own continent, seem to have been just as well adapted to an aquatic life as the whales, and even better than the seals, and we can see no reason why columbus should not have found these creatures still disporting themselves in the gulf of mexico. the best we can do is to fall back on an unknown "law of progress," and say that the trend of life is toward the replacement of large, lower animals by those smaller and intellectually higher. but _why_ there should be an allotted course to any group of animals, why some species come to an end when they are seemingly as well fitted to endure as others now living, we do not know, and if we say that a time comes when the germ-plasm is incapable of further subdivision, we merely express our ignorance in an unnecessary number of words. the mammoth and mastodon have already been cited as instances of animals that have unaccountably become extinct, and these examples are chosen from among many on account of their striking nature. the great ground sloths, the mylodons, megatheres, and their allies, are another case in point. at one period or another they reached from oregon to virginia, florida, and patagonia, though it is not claimed that they covered all this area at one time. and, while it may be freely admitted that in some portions of their range they may have been extirpated by a change in food-supply, due in turn to a change in climate, it seems preposterous to claim that there was not at all times, somewhere in this vast expanse of territory, a climate mild enough and a food-supply large enough for the support of even these huge, sluggish creatures. we may evoke the aid of primitive man to account for the disappearance of this race of giants, and we know that the two were coeval in patagonia, where the sloths seem to have played the rôle of domesticated animals, but again it seems incredible that early man, with his flint-tipped spears and arrows, should have been able to slay even such slow beasts as these to the very last individual. of course, in modern times man has directly exterminated many animals, while by the introduction of dogs, cats, pigs, and goats he has indirectly not only thinned the ranks of animals, but destroyed plant life on an enormous scale. but in the past man's capabilities for harm were infinitely less than now, while of course the greatest changes took place before man even existed, so that, while he is responsible for the great changes that have taken place in the world's flora and fauna during recent times, his influence, as a whole, has been insignificant. thus, while man exterminated the great northern sea-cow, rytina, and pallas's cormorant on the commander islands, these animals were already restricted to this circumscribed area[ ] by natural causes, so that man but finished what nature had begun. the extermination of the great auk in european waters was somewhat similar. there is, however, this unfortunate difference between extermination wrought by man and that brought about by natural causes: the extermination of species by nature is ordinarily slow, and the place of one is taken by another, while the destruction wrought by man is rapid, and the gaps he creates remain unfilled. [ ] _it is possible that the cormorant may always have been confined to this one spot, but this is probably not the case with the sea-cow._ not so very long ago it was customary to account for changes in the past life of the globe by earthquakes, volcanic outbursts, or cataclysms of such appalling magnitude that the whole face of nature was changed, and entire races of living beings swept out of existence at once. but it is now generally conceded that while catastrophes have occurred, yet, vast as they may have been, their effects were comparatively local, and, while the life of a limited region may have been ruthlessly blotted out, life as a whole was but little affected. the eruption of krakatoa shook the earth to its centre and was felt for hundreds of miles around, yet, while it caused the death of thousands of living beings, it remains to be shown that it produced any effect on the life of the region taken in its entirety. changes in the life of the globe have been in the main slow and gradual, and in response to correspondingly slow changes in the level of portions of the earth's crust, with their far-reaching effects on temperature, climate, and vegetation. animals that were what is termed plastic kept pace with the altering conditions about them and became modified, too, while those that could not adapt themselves to their surroundings died out. how slowly changes may take place is shown by the occurrence of a depression in the isthmus of panama, in comparatively recent geologic time, permitting free communication between the atlantic and pacific, a sort of natural inter-oceanic canal. and yet the alterations wrought by this were, so to speak, superficial, affecting only some species of shore fishes and invertebrates, having no influence on the animals of the deeper waters. again, on the pacific coast are now found a number of shells that, as we learn from fossils, were in pliocene time common on both coasts of the united states, and mr. dall interprets this to mean that when this continent was rising, the steeper shore on the pacific side permitted the shell-fish to move downward and adapt themselves to the ever changing shore, while on the atlantic side the drying of a wide strip of level sea-bottom in a relatively short time exterminated a large proportion of the less active mollusks. and in this instance "relatively short" means positively long; for, compared to the rise of a continent from the ocean's bed, the flow of a glacier is the rapid rush of a mountain torrent. then, too, while a tendency to vary seems to be inherent in animals, some appear to be vastly more susceptible than others to outside influences, to respond much more readily to any change in the world about them. in fact, professor cook has recently suggested that the inborn tendency to variation is sufficient in itself to account for evolution, this tendency being either repressed or stimulated as external conditions are stable or variable. the more uniform the surrounding conditions, and the simpler the animal, the smaller is the liability to change, and some animals that dwell in the depths of the ocean, where light and temperature vary little, if any, remain at a standstill for long periods of time. the genus lingula, a small shell, traces its ancestry back nearly to the base of the ordovician system of rocks, an almost inconceivable lapse of time, while one species of brachiopod shell endures unchanged from the trenton limestone to the lower carboniferous. in the first case one species has been replaced by another, so that the shell of to-day is not exactly like its very remote ancestor, but that the type of shell should have remained unchanged when so many other animals have arisen, flourished for a time, and perished, means that there was slight tendency to variation, and that the surrounding conditions were uniform. says professor brooks, speaking of lingula: "the everlasting hills are the type of venerable antiquity; but lingula has seen the continents grow up, and has maintained its integrity unmoved by the convulsions which have given the crust of the earth its present form." many instances of sudden but local extermination might be adduced, but among them that of the tile-fish is perhaps the most striking. this fish, belonging to a tropical family having its headquarters in the gulf of mexico, was discovered in in moderately deep water to the southward of massachusetts and on the edge of the gulf stream, where it was taken in considerable numbers. in the spring of vessels arriving at new york reported having passed through great numbers of dead and dying fishes, the water being thickly dotted with them for miles. from samples brought in, it was found that the majority of these were tile-fish, while from the reports of various vessels it was shown that the area covered by dead fish amounted to somewhere between , and , square miles, and the total number of dead was estimated at not far from _a billion_. this enormous and widespread destruction is believed to have been caused by an unwonted duration of northerly and easterly winds, which drove the cold arctic current inshore and southwards, chilling the warm belt in which the tile-fish resided and killing all in that locality. it was thought possible that the entire race might have been destroyed, but, while none were taken for many years, in and in a number were caught, showing that the species was beginning to reoccupy the waters from which it had been driven years before. the effect of any great fall in temperature on animals specially adapted to a warm climate is also illustrated by the destruction of the manatees in the sebastian river, florida, by the winter of - , which came very near exterminating this species. readers may remember that this was the winter that wrought such havoc with the blue-birds, while in the vicinity of washington, d. c., the fish-crows died by hundreds, if not by thousands. fishes may also be exterminated over large areas by outbursts of poisonous gases from submarine volcanoes, or more rarely by some vast lava flood pouring into the sea and actually cooking all living beings in the vicinity. and in the past these outbreaks took place on a much larger scale than now, and naturally wrought more widespread destruction. a recent instance of local extermination is the total destruction of a humming-bird, _bellona ornata_, peculiar to the island of st. vincent, by the west indian hurricane of , but this is naturally extirpation on a very small scale. still, the problems of nature are so involved that while local destruction is ordinarily of little importance, or temporary in its effects, it may lead to the annihilation of a species by breaking a race of animals into isolated groups, thereby leading to inbreeding and slow decline. the european bison, now confined to a part of lithuania and a portion of the caucasus, seems to be slowly but surely approaching extinction in spite of all efforts to preserve the race, and no reason can be assigned for this save that the small size of the herds has led to inbreeding and general decadence. in other ways, too, local calamity may be sweeping in its effects, and that is by the destruction of animals that resort to one spot during the breeding season, like the fur-seals and some sea-birds, or pass the winter months in great flocks or herds, as do the ducks and elk. the supposed decimation of the moas by severe winters has been already discussed, and the extermination of the great auk in european waters was indirectly due to natural causes. these birds bred on the small, almost inaccessible island of eldey, off the coast of iceland, and when, through volcanic disturbances, this islet sank into the sea, the few birds were forced to other quarters, and as these were, unfortunately, easily reached, the birds were slain to the last one. from the great local abundance of their remains, it has been thought that the curious short-legged pliocene rhinoceros, _aphelops fossiger_, was killed off in the west by blizzards when the animals were gathered in their winter quarters, and other long-extinct animals, too, have been found under such conditions as to suggest a similar fate. among local catastrophes brought about by unusually prolonged cold may be cited the decimation of the fur-seal herds of the pribilof islands in and , when the breeding seals were prevented from landing by the presence of ice-floes, and perished by thousands. peculiar interest is attached to this case, because the restriction of the northern fur-seals to a few isolated, long undiscovered islands, is believed to have been brought about by their complete extermination in other localities by prehistoric man. had these two seasons killed all the seals, it would have been a reversal of the customary extermination by man of a species reduced in numbers by nature. in the case of large animals another element probably played a part. the larger the animal, the fewer young, as a rule, does it bring forth at a birth, the longer are the intervals between births, and the slower the growth of the young. the loss of two or three broods of sparrows or two or three litters of rabbits makes comparatively little difference, as the loss is soon supplied, but the death of the young of the larger and higher mammals is a more serious matter. a factor that has probably played an important rôle in the extinction of animals is the relation that exists between various animals, and the relations that also exist between animals and plants, so that the existence of one is dependent on that of another. thus no group of living beings, plants or animals, can be affected without in some way affecting others, so that the injury or destruction of some plant may result in serious harm to some animal. nearly everyone is familiar with the classic example given by darwin of the effect of cats on the growth of red clover. this plant is fertilized by bumble bees only, and if the field mice, which destroy the nests of the bees, were not kept in check by cats, or other small carnivores, their increase would lessen the numbers of the bees and this in turn would cause a dearth of clover. the yuccas present a still more wonderful example of the dependence of plants on animals, for their existence hangs on that of a small moth whose peculiar structure and habits bring about the fertilization of the flower. the two probably developed side by side until their present state of inter-dependence was reached, when the extinction of the one would probably bring about that of the other. it is this inter-dependence of living things that makes the outcome of any direct interference with the natural order of things more or less problematical, and sometimes brings about results quite different from what were expected or intended. the gamekeepers on the grouse moors of scotland systematically killed off all birds of prey because they caught some of the grouse, but this is believed to have caused far more harm than good through permitting weak and sickly birds, that would otherwise have fallen a prey to hawks, to live and disseminate the grouse distemper. the destruction of sheep by coyotes led the state of california to place a bounty on the heads of these animals, with the result that in eighteen months the state was called upon to pay out $ , . as a result of the war on coyotes the animals on which they fed, notably the rabbits, increased so enormously that in turn a bounty was put on rabbits, the damage these animals caused the fruit-growers being greater than the losses among sheep-owners from the depredations of coyotes. and so, says dr. palmer, "in this remarkable case of legislation a large bounty was offered by a county in the interest of fruit-growers to counteract the effects of a state bounty expended mainly for the benefit of sheep-owners!" professor shaler, in noting the sudden disappearance of such trees as the gums, magnolias, and tulip poplars from the miocene flora of europe has suggested that this may have been due to the attacks, for a series of years, of some insect enemy like the gipsy moth, and the theory is worth considering, although it must be looked upon as a possibility rather than a probability. still, anyone familiar with the ravages of the gipsy moth in massachusetts, where the insect was introduced by accident, can readily imagine what _might_ have been the effect of some sudden increase in the numbers of such a pest on the forests of the past. trees might resist the attacks of enemies and the destruction of their leaves for two or three years, but would be destroyed by a few additional seasons of defoliation. ordinarily the abnormal increase of any insect is promptly followed by an increase in the number of its enemies; the pest is killed off, the destroyers die of starvation and nature's balance is struck. but if by some accident, such as two or three consecutive seasons of wet, drought, or cold, the natural increase of the enemies was checked, the balance of nature would be temporarily destroyed and serious harm done. that such accidents may occur is familiar to us by the damage wrought in florida and other southern states by the unwonted severity of the winters of , , and . if any group of forest trees was destroyed in the manner suggested by professor shaler, the effects would be felt by various plants and animals. in the first place, the insects that fed on these trees would be forced to seek another source of food and would be brought into a silent struggle with forms already in possession, while the destruction of one set of plants would be to the advantage of those with which they came into competition and to the disadvantage of vegetation that was protected by the shade. finally, these changed conditions would react in various ways on the smaller birds and mammals, the general effect being, to use a well-worn simile, like that of casting a stone into a quiet pool and setting in motion ripples that sooner or later reach to every part of the margin. it is scarcely necessary to warn the reader that for the most part this is purely conjectural, for from the nature of the case it is bound to be so. but it is one of the characteristics of educated man that he wishes to know the why and wherefore of everything, and is in a condition of mental unhappiness until he has at least formulated some theory which seems to harmonize with the visible facts. and from the few glimpses we get of the extinction of animals from natural causes we must formulate a theory to fit the continued extermination that has been taking place ever since living beings came into the world and were pitted against one another and against their surroundings in the silent and ceaseless struggle for existence. the end. index _the asterisk denotes that the animal or object is figured on or opposite the page referred to._ Æpyornis, egg of, , ,* , eggs found in swamps, ; found floating, eggs used for bowls, origin of fable of roc, , alaskan live mammoth story, - , anomoepus tracks, apteryx egg, archæopteryx, description of, , discovery of, earliest known bird, restoration, * specimens of, ,* wing, ,* archelon, a great turtle, basilosaurus, see also zeuglodon beehler, l. w., , birds, always clad in feathers, , earliest, birds, first intimation of, rarity of fossil, , related to reptiles, wings of embryonic, with teeth, , bison, european, books of reference, xix, , , , , , , , , , , breeding of large animals, brontornis, size of leg-bones, brontosaurus, size of bones, ,* ,* brooks, w. k., on lingula, buffalo legend, buttons as vestigial structures, carcharodon auriculatus, teeth, megalodon, estimated size, teeth, , carson city footprints, casts, how formed, , cats and clover, cephalaspis, * ceratosaurus, habits, restoration, * skull, * changes in nature slow, cheirotherium, chlamydosaurus, claosaurus. see thespesius climate, changes in western united states, clover and cats, cold, effects of, on animals, , , cold winters, collecting fossils, , - color of large land animals, of young animals, covering of extinct animals sometimes indicated, , coyotes, effect of their destruction on fruit, dall, w. h., theory as to extinction of mollusks, dinosaurs, bones of, , brain of, collections of, compared to marsupials, first discovered, food required by, hip-bones mistaken for shoulder-blade, professor marsh's epitaph for, range, recognized as new order of reptiles, related to ostrich and alligator, size of, , , tracks, ascribed to birds, dinotherium, diplodocus, estimated weight, supposed habits, egg of Æpyornis, , ; apteryx, ; ostrich, ; moa, eggs, casts of, elephant, size, size of tusks, , elephas ganesa, tusks, encrustations, extermination. see extinction extinction, ascribed to great convulsions, ascribed to primitive man, , of dinosaurs, local, by man, , of marine reptiles, often unaccountable, , of pliocene rhinoceros, sometimes evolution, , of titanotheres, feathers, imprints of, , fishes, abundance of, armored, , , , collections of, killed by cold, killed by volcanoes, fish-crows, killed by cold, flesh does not petrify, flightless birds, absent from tasmania, present distribution, , relation between flightlessness and size, folds and frills, footprints, collections of, books on, see also under tracks fossil birds, rarity of, fossil man, fossilization a slow process, fossils, conditions under which they are formed, , collecting, - definition of, deformation of, impressions, , not necessarily petrifactions, preparation of, - why they are not more common, , , fowls, muscles of, frill of triceratops, fur-seals killed by ice-floes, gar pikes, destruction of, giant birds, reasons for distribution and flightlessness, giant moa, leg compared with that of horse, * giant sloth, domesticated by man, struggle between, giant sloth, tracks at carson city, gilfort, robert, great auk, extermination of, grouse on scotch moors, hawkins, b. w., restorations by, hesperornis, description of, impressions of feathers, position of legs, , restoration of, * hippotherium, , hoactzin, habits of, , * horn does not petrify, horse, abundant in pleistocene time, books on, of bronze age, , collections of fossil, development of, , ,* differences between fossil and living, early domestication, evidence as to genealogy, - extra-toed, , found in south america in , of julius cæsar, none found wild in historic times, pliocene, possibility of existence in america up to the time of its discovery, , primitive, , * horse, sketched by primitive man, teeth of, three-toed, humming-bird, exterminated by hurricane, hydrarchus, * hyracotherium, , ,* , ichthyosaurs, silhouettes of, iguanodons, found at bernissart, impressions of feathers, of scales, of skin, inbreeding, effects of, , information, sources of, xvi innuits, habits, interdependence of animals and plants, , , ivory, fossil, , , , jaw of mosasaur, * of reptiles, killing of the mammoth, story, , kimmswick, deposit of mastodon bones, knight, charles r., restorations by, xviii, koch's hydrarchus, , * missourium, ,* leaves, impressions of, , leg of brontornis, * leg of the great brontosaurus, * of giant moa, * position in hesperornis, position in ducks, lenape stone, , , * life, earliest traces of, , lingula, antiquity of, professor brooks on, loricaria, * mammoth, adapted to a cold climate, alaskan live, story, believed to live underground, bones taken for those of giants, contemporary with man, derivation of name, description, discovery of entire specimens, , distribution, , drawn by early man, , * entire specimens obtainable, reasons for extermination, killing of the, literature on, misconception as to size, mounted skeleton, not now living, preservation of remains, skeletons in alaska, , mammoth, in chicago academy of sciences, at st. petersburg, * restoration, * size, , , size of tusks, , teeth, , * teeth dredged in north sea, tusks brought into market, , man contemporary with mammoth, fossil, of guadeloupe, manatees killed by cold, marsh, prof. o. c., collection of fossil horses, on dinosaurs, on toothed birds, , mastodon, bones taken for those of giants, thought to be carnivorous, covering, description, distribution, , , extinction, literature, and man, , first noticed in america, origin unknown, remains abundant, , remains in ulster and orange counties, new york, , restoration, * mastodon, size, skeletons on exhibition, species, teeth, , ,* tusks, , mesohippus, mimicry, not conscious, missourium of koch, ,* moas, collections of, , contemporary with man, , deductions from distribution, destruction of, , discovery of bones, elephant-footed, feathers of, giant, supposed food of, legends of, , literature, scientific names, size of, species of, moloch, an australian lizard, * mosasaurs, abundance of, in kansas, books on, collections of, extinction of, first discovery, jaw of, * mosasaurs, range of, restoration, * size of, , mylodon tracks at carson city, names, scientific, reasons for using, xvi, xvii nature, balance of, nuts, fossil, oldest animals, vertebrates, , ostrich egg, over-specialization, , peale, c. w., peale, rembrandt, , pelican, mandible, penguins, depend on fat for warmth, feathers highly modified, swim with wings, petrified bodies, phororhacos, description of, mistaken for mammal, patagonian bird, related to heron family, restoration, frontispiece skull, , * protohippus, pteraspis, pterichthys, , , * mistaken for crab, pterodactyls, impressions of wings, from kansas, wing, * pycraft, w. p., restoration of archæopteryx, radiolarians, , * reconstruction of animals, , , reptiles, fasting powers of, growth throughout life, jaws, restorations, xviii archæopteryx, * ceratosaurus, * hesperornis, * mammoth, * mastodon, * phororhacos, frontispiece progress in, stegosaurus, * thespesius, * triceratops, * tylosaurus, * reversion of fancy stock, rhinoceros, exterminated by cold, roc, legend of, , rocks, thickness of sedimentary, ruffles on dresses, schuchert, charles, on collecting fossils, collector of zeuglodon bones, seals, covering of, sea-serpent, belief in, possibility of existence, shaler, professor, on changes in miocene flora of europe, , sharks, early, great-toothed, known from spines and teeth, port jackson, teeth of, white, or man-eater, skeleton, basis of all restorations, best testimony of animal's relationships, information to be derived from, , , , , , , a problem in mechanics, , reconstruction of, relation of, to exterior of animal, , of triceratops, ,* spines and plates, stegosaurus, description of, restoration of, * survival of the fittest, teeth, birds with, of gnawing animals, , of grass-eaters, teeth, of horse, of mammoth, , * of mastodon, , * of sharks, , of thespesius, thespesius, abundance of, , brain of, (same as claosaurus) engulfed in quicksand, impressions of skin, restoration of, * teeth of, at yale, tiger, preying on reindeer, tile-fish, destruction of, titanichthys, , toothed birds, collections of, discovery of, townsend c. h., - tracks, ascribed to birds, ascribed to giants, animals known from, collections of, of connecticut valley, deductions from, of dinosaurs, ,* ,* , * discovery in england and america, , how formed, , at hastings, tracks, of mylodon, of worms, , triceratops, brain, broken horn, description, , restoration, * skeleton, * tufa, tukeman, killing of the mammoth, , variation in animals, vertebrates, oldest, vestigial structures, , volcanic outbursts, , webster, f. s., on destruction of gar pikes, white, c. a., on the nature and uses of fossils, white shark, wings, , ,* of embryonic birds, wood, fossil, , worm trails, , yucca, fertilization, zeuglodon, abundance of remains, same as basilosaurus description, , habits, zeuglodon, koch's restoration, name, , once numerous, size, specimen of, structure of bones, teeth, , * wisconsin geological and natural history survey. e. a. birge, director. c. r. van hise, consulting geologist. bulletin no. v. educational series no. . the geography of the region about devil's lake and the dalles of the wisconsin, with some notes on its surface geology. by rollin d. salisbury, a. m., _professor of geographic geology, university of chicago,_ and wallace w. atwood, b. s., _assistant in geology, university of chicago._ madison, wis. published by the state. . wisconsin geological and natural history survey. ------------------------------------------------------------------- board of commissioners. edward scofield, governor of the state. l. d. harvey, state superintendent of public instruction. charles k. adams, president, president of the university of wisconsin. edwin e. bryant, vice-president, president of the commissioners of fisheries. charles s. slichter, secretary, president of the wisconsin academy of sciences, arts, and letters. -------------------------------------------------------------- e. a. birge, director of the survey. c. r. van hise, consulting geologist. e. r. buckley, assistant geologist. in charge of economic geology. s. weidman, assistant geologist. in charge of geology of wausau district. l. s. smith, in charge of hydrography. s. v. peppel, chemist. f. r. denniston, artist. [illustration: the dalles of the wisconsin.] contents. --------------------------------------------------------- part i. the topography with some notes on the surface geology. chapter i. general geographic features i. the plain surrounding the quartzite ridges. topography structure origin of the sandstone and limestone origin of the topography ii. the quartzite ridges topography the structure and constitution of the ridges iii. relations of the sandstone of the plain to the quartzite of the ridges part ii. history of the topography. chapter ii. outline of the history of the rock formations which show themselves at the surface. i. the pre-cambrian history of the quartzite from loose sand to quartzite uplift and deformation. dynamic metamorphism erosion of the quartzite thickness of the quartzite ii. the history of the paleozoic strata the subsidence the potsdam sandstone (and conglomerate) the lower magnesian limestone the st. peters sandstone younger beds climatic conditions time involved the uplift chapter iii. general outline of rain and river erosion elements of erosion weathering corrasion erosion without valleys the beginning of a valley the course of a valley tributary valleys how a valley gets a stream limits of a valley a cycle of erosion effects of unequal hardness falls and rapids narrows erosion of folded strata base-level plains and peneplains transportation and deposition topographic forms resulting from stream deposition rejuvenation of streams underground water chapter iv. erosion and the development of striking scenic features establishment of drainage striking scenic features the baraboo bluffs the narrows in the quartzite glens natural bridge the dalles of the wisconsin the mounds and castle rocks chapter v. the glacial period. the drift snow fields and ice sheets the north american ice sheets the work of glacier ice erosive work of ice. effect on topography deposition by the ice. effect on topography direction of ice movement effect of topography on movement glacial deposits the ground moraine constitution topography terminal moraines topography of terminal moraines the terminal moraine about devil's lake the moraine on the main quartzite range constitution of the marginal ridge the slope of the upper surface of the ice at the margin stratified drift its origin glacial drainage stages in the history of an ice sheet deposits made by extraglacial waters during the maximum extension of the ice at the edge of the ice, on land beyond the edge of the ice, on land deposits at and beyond the edge of the ice in standing water deposits made by extraglacial waters during the retreat of the ice deposits made by extraglacial waters during the advance of the ice deposits made by subglacial streams relations of stratified to unstratified drift complexity of relations classification of stratified drift on the basis of position extraglacial deposits supermorainic deposits the submorainic (basal) deposits intermorainic stratified drift changes in drainage effected by the ice while the ice was on wisconsin lake baraboo lake devil's lake in glacial times after the ice had disappeared lakes existing lakes changes in streams skillett creek the wisconsin the driftless area contrast between glaciated and unglaciated areas topography drainage mantle rock list of illustrations. ------------------------------------------------------------ plates. plate frontispiece. the dalles of the wisconsin i. general map of the devil's lake region ii. local map of the devil's lake region iii. fig. --ripple marks on a slab of sandstone fig. --piece of potsdam conglomerate iv. lower narrows of the baraboo v. devil's lake notch vi. east bluff of devil's lake vii. east bluff at the upper narrows of the baraboo near ableman's viii. vertical shear zone face of east bluff at devil's lake ix. massive quartzite in situ in road through upper narrows near ableman's x. brecciated quartzite xi. northwest wall of the upper narrows xii. steamboat rock xiii. fig. --a very young valley fig. --a valley at later stage of development fig. --young valleys xiv. fig. --same valleys as shown in pl. xiii, fig. , but at a later stage of development fig. --same valleys as shown in fig. in later stage of development xv. diagram illustrating how a hard inclined layer of rock becomes a ridge in the process of degradation xvi. skillett falls xvii. a group of mounds on the plain northwest from camp douglas xviii. castle rock near camp douglas xix. fig. --sketch of a young valley fig. --same valleys as shown in fig. in later stage of development xx. fig. --sketch of a part of a valley at a stage of development corresponding to the cross section shown in figure fig. --sketch of a section of the baraboo valley xxi. cleopatra's needle xxii. turk's head xxiii. devil's doorway xxiv. talus slope on east bluff of devil's lake xxv. dorward's glen xxvi. natural bridge near denzer xxvii. the navy yard xxviii. chimney rock xxix. an island in the lower dalles xxx. view in lower dalles xxxi. stand rock xxxii. petenwell peak xxxiii. north american ice sheet xxxiv. owl's head xxxv. cut in glacial drift xxxvi. glaciated stones xxxvii. topographic map of a small area about devil's lake xxxviii. distorted laminæ of silt and clay figures in text. figure . profile across the baraboo quartzite ranges through baraboo . profile across the baraboo ranges through merrimac transcriber's note: there is no figure . . diagram showing the structure of the quartzite . diagram showing the relation of the potsdam sandstone to the baraboo quartzite . diagram illustrating effect of faulting on outcrop . diagram showing the disposition of sediments about an island . the same as after subsidence . diagram showing relation of potsdam conglomerate to quartzite at devil's lake . cross section of a delta . the geological formations of southern wisconsin . a typical river system . diagram illustrating the relations of ground water to streams . diagram illustrating the shifting of divides . diagram showing topography at the various stages of an erosion cycle . diagram illustrating the development of rapids and falls . sketch looking northwest from camp douglas . diagrammatic cross section of a young valley . diagrammatic profile of a young valley . diagrammatic cross section of a valley in a later stage of development . the same at a still later stage . diagram illustrating the topographic effect or rejuvenation of a stream by uplift . normal profile of a valley bottom . profile of a stream rejuvenated by uplift . diagram illustrating monoclinal shifting . diagram showing the relation of the potsdam sandstone to the quartzite at the upper narrows . diagrammatic cross section of a field of ice and snow . shape of an erosion hill before glaciation . the same after glaciation . diagram showing the effect of a valley on the movement of ice . the same under different conditions . diagram showing the relation of drift to the underlying rock where the drift is thick . the same where the drift is relatively thin . diagrammatic representation of the effect of a hill on the edge of the ice . the same at a later stage of the ice advance . map showing the relation of the ice lobes during the wisconsin epoch of the glacial period . sketch of the terminal moraine topography east of devil's lake . cut through the terminal moraine east of kirkland . cross section of the marginal ridge of the moraine on the south slope of the devil's nose . cross section of the marginal ridge of the moraine on the crest of the quartzite range . morainic outwash plain . the same in other relations . skillett creek and its peculiarities . the wisconsin valley near kilbourn city . drainage in the driftless area . drainage in the glaciated area . section in the driftless region showing relation of the soil to the solid rock beneath part i. ------------------------------------------------------------ the topography. with some notes on the surface geology. geography and surface geology of the devil's lake region. chapter i. general geographic features. this report has to do with the physical geography of the area in south central wisconsin, shown on the accompanying sketch map, plate i. the region is of especial interest, both because of its striking scenery, and because it illustrates clearly many of the principles involved in the evolution of the geography of land surfaces. generally speaking, the region is an undulating plain, above which rise a few notable elevations, chief among which are the baraboo quartzite ranges, marked by diagonal lines on plates i and ii. these elevations have often been described as two ranges. the south or main range lies three miles south of baraboo, while the north or lesser range, which is far from continuous, lies just north of the city. the main range has a general east-west trend, and rises with bold and sometimes precipitous slopes to feet above its surroundings. a deep gap three or four miles south of baraboo (plates ii, v, and xxxvii) divides the main range into an eastern and a western portion, known respectively as the _east and west bluffs_ or _ranges_. in the bottom of the gap lies devil's lake (i, plate ii and plate xxxvii), perhaps the most striking body of water of its size in the state, if not in the whole northern interior. a general notion of the topography of a small area in the immediate vicinity of the lake may be obtained from plate xxxvii. the highest point in the range is about four miles east of the lake, and has an elevation of more than , feet above sea level, more than , feet above lake michigan, and about feet above the baraboo valley at its northern base. the eastward extension of the west range (plate xxxvii) lying south of the lake, and popularly known as the _devil's nose_, reaches an elevation of a little more than , feet. the lesser or north quartzite range (plate ii) rises feet to feet above its surroundings. it assumes considerable prominence at the upper and lower narrows of the baraboo (b and c, plate ii, c, plate xxxvii and plate iv). the north range is not only lower than the south range, but its slopes are generally less steep, and, as plate ii shows, it is also less continuous. the lesser elevation and the gentler slopes make it far less conspicuous. about three miles southwest of portage (plate ii) the north and south ranges join, and the elevation at the point of union is about feet above the wisconsin river a few miles to the east. the lower country above which these conspicuous ridges rise, has an average elevation of about , feet above the sea, and extends far beyond the borders of the area with which this report is concerned. the rock underlying it in the vicinity of baraboo is chiefly sandstone, but there is much limestone farther east and south, in the area with which the baraboo region is topographically continuous. both the sandstone and limestone are much less resistant than the quartzite, and this difference has had much to do with the topography of the region. the distinctness of the quartzite ridges as topographic features is indicated in plate xxxvii by the closeness of the contour lines on their slopes. the same features are shown in figs. and , which represent profiles along two north-south lines passing through baraboo and merrimac respectively. [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. i. general map showing the location of the chief points mentioned in this report. the location of the area shown in plate xxxvii, centering about baraboo, is indicated.] [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. ii. map of area considered in this report.] [illustration: fig. .--profile along a line extending due north and south from baraboo across the north and south ranges. the dotted continuation northward, represents the extension of the profile beyond the topographic map, plate xxxvii.] [illustration: fig. .--profile north from merrimac across the quartzite ranges. the dotted continuation northward represents the extension of the profile beyond the topographic map, plate xxxvii.] i. the plain surrounding the quartzite ridges. _topography._--as seen from the top of the quartzite ridges, the surrounding country appears to be an extensive plain, but at closer range it is seen to have considerable relief although there are extensive areas where the surface is nearly flat. the relief of the surface is of two somewhat different types. in some parts of the area, especially in the western part of the tract shown on plate ii, the surface is made up of a succession of ridges and valleys. the ridges may be broken by depressions at frequent intervals, but the valleys are nowhere similarly interrupted. it would rarely be possible to walk along a ridge or "divide" for many miles without descending into valleys; but once in a valley in any part of the area, it may be descended without interruption, until the baraboo, the wisconsin, the mississippi, and finally the gulf is reached. in other words, the depressions are continuous, but the elevations are not. this is the first type of topography. where this type of topography prevails its relation to drainage is evident at a glance. all the larger depressions are occupied by streams continuously, while the smaller ones contain running water during some part of the year. the relations of streams to the depressions, and the wear which the streams effect, whether they be permanent or temporary, suggest that running water is at least one of the agencies concerned in the making of valleys. an idea of the general arrangement of the valleys, as well as many suggestions concerning the evolution of the topography of the broken plain in which they lie might be gained by entering a valley at its head, and following it wherever it leads. at its head, the valley is relatively narrow, and its slopes descend promptly from either side in such a manner that a cross-section of the valley is v-shaped. in places, as west of camp douglas, the deep, steep-sided valleys are found to lead down and out from a tract of land so slightly rolling as to be well adapted to cultivation. following down the valley, its progressive increase in width and depth is at once evident, and at the same time small tributary valleys come in from right and left. at no great distance from the heads of the valleys, streams are found in their bottoms. as the valleys increase in width and depth, and as the tributaries become more numerous and wider, the topography of which the valleys are a feature, becomes more and more broken. at first the tracts between the streams are in the form of ridges, wide if parallel valleys are distant from one another, and narrow if they are near. the ridges wind with the valleys which separate them. whatever the width of the inter-stream ridges, it is clear that they must become narrower as the valleys between them become wider, and in following down a valley a point is reached, sooner or later, where the valleys, main and tributary, are of such size and so numerous that their slopes constitute a large part of the surface. where this is true, and where the valleys are deep, the land is of little industrial value except for timber and grazing. when, in descending a valley system, this sort of topography is reached, the roads often follow either the valleys or the ridges, however indirect and crooked they may be. where the ridges separating the valleys in such a region have considerable length, they are sometimes spoken of as "hog backs." still farther down the valley system, tributary valleys of the second and lower orders cross the "hog backs," cutting them into hills. by the time this sort of topography is reached, a series of flats is found bordering the streams. these flats may occur on both sides of the stream, or on but one. the topography and the soil of these flats are such as to encourage agriculture, and the river flats or alluvial plains are among the choicest farming lands. with increasing distance from the heads of the valleys, these river plains are expanded, and may be widened so as to occupy the greater part of the surface. the intervening elevations are there relatively few and small. their crests, however, often rise to the same level as that of the broader inter-stream areas farther up the valleys. the relations of the valleys and the high lands separating them, is such as to suggest that there are, generally speaking, two sets of flat surfaces, the higher one representing the upland in which the valleys lie, the lower one representing the alluvial plains of the streams. the two sets of flats are at once separated and connected by slopes. at the head of a drainage system, the upland flats predominate; in the lower courses, the river plains; in an intermediate stage, the slopes are more conspicuous than either upper or lower flat. southwest from devil's lake and northwest from sauk city, in the valley of honey creek, and again in the region southwest from camp douglas, the topography just described is well illustrated. in both these localities, as in all others where this type of topography prevails, the intimate relations of topography and drainage cannot fail to suggest that the streams which are today widening and deepening the valleys through which they flow, had much to do with their origin and development. this hypothesis, as applied to the region under consideration, may be tested by the study of the structure of the plain. the second type of topography affecting the plain about the quartzite ranges is found east of a line running from kilbourn city to a point just north of prairie du sac. though in its larger features the area east of this line resembles that to the west, its minor features are essentially different. here there are many depressions which have no outlets, and marshes, ponds, and small lakes abound. not only this, but many of the lesser elevations stand in no definite relation to valleys. the two types of topography make it clear that they were developed in different ways. _structure._--examination of the country surrounding the baraboo ridges shows that its surface is underlaid at no great depth by horizontal or nearly horizontal beds of sandstone and limestone (see plates xvi, xxviii, and frontispiece). these beds are frequently exposed on opposite sides of a valley, and in such positions the beds of one side are found to match those on the other. this is well shown along the narrow valley of skillett creek just above the "pewit's nest." here the swift stream is rapidly deepening its channel, and it is clear that a few years hence, layers of sandstone which are now continuous beneath the bed of the creek will have been cut through, and their edges will appear on opposite sides of the valley just as higher layers do now. here the most skeptical might be convinced that the layers of rock on either side of the narrow gorge were once continuous across it, and may see, at the same time, the means by which the separation was effected. between the slight separation, here, where the valley is narrow, and the great separation where the valleys are wide, there are all gradations. the study of progressively wider valleys, commencing with such a gorge as that referred to, leaves no room for doubt that even the wide valleys, as well as the narrow ones, were cut out of the sandstone by running water. [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. iii. illustration: fig. . ripple marks on a slab of potsdam sandstone. illustration: fig. . piece of potsdam conglomerate. the larger pebbles are about three inches in diameter.] the same conclusion as to the origin of the valleys may be reached in another way. either the beds of rock were formed with their present topography, or the valleys have been excavated in them since they were formed. their mode of origin will therefore help to decide between these alternatives. _origin of the sandstone and limestone._--the sandstone of the region, known as the potsdam sandstone, consists of medium sized grains of sand, cemented together by siliceous, ferruginous, or calcareous cement. if the cement were removed, the sandstone would be reduced to sand, in all respect similar to that accumulating along the shores of seas and lakes today. the surfaces of the separate layers of sandstone are often distinctly ripple-marked (fig. , pl. iii), and the character of the markings is identical in all essential respects with the ripples which affect the surface of the sand along the shores of devil's lake, or sandy beaches elsewhere, at the present time. these ripple marks on the surfaces of the sandstone layers must have originated while the sand was movable, and therefore before it was cemented into sandstone. in the beds of sandstone, fossils of marine animals are found. shells, or casts of shells of various sorts are common, as are also the tracks and burrowings of animals which had no shells. among these latter signs of life may be mentioned the borings of worms. these borings are not now always hollow, but their fillings are often so unlike the surrounding rock, that they are still clearly marked. these worm borings, like the ripple marks, show that the sand was once loose. the basal beds of the sandstone are often conglomeratic. the conglomeratic layers are made up of water-worn pieces of quartzite, plate iii, fig. , ranging in size from small pebbles to large bowlders. the interstices of the coarse material are filled by sand, and the whole cemented into solid rock. the conglomeratic phase of the sandstone may be seen to advantage at parfrey's glen (a, plate xxxvii) and dorward's glen, (b, same plate) on the east bluff of devil's lake above the cliff house, and at the upper narrows of the baraboo, near ablemans. it is also visible at numerous other less accessible and less easily designated places. from these several facts, viz.: the horizontal strata, the ripple-marks on the surfaces of the layers, the fossils, the character of the sand, and the water-worn pebbles and bowlders of the basal conglomerate, positive conclusions concerning the origin of the formation may be drawn. the arrangement in definite layers proves that the formation is sedimentary; that is, that its materials were accumulated in water whither they had been washed from the land which then existed. the ripple-marks show that the water in which the beds of sand were deposited was shallow, for in such water only are ripple-marks made.[ ] once developed on the surface of the sand they may be preserved by burial under new deposits, just as ripple-marks on sandy shores are now being buried and preserved. [ ] ripple marks are often seen on the surface of wind-blown sand, but the other features of this sandstone show that this was not its mode of accumulation. the conglomerate beds of the formation corroborate the conclusions to which the composition and structure of the sandstone point. the water-worn shapes of the pebbles and stones show that they were accumulated in water, while their size shows that the water must have been shallow, for stones of such sizes are handled only by water of such slight depth that waves or strong currents are effective at the bottom. furthermore, the large bowlders show that the source of supply (quartzite) must have been close at hand, and that therefore land composed of this rock must have existed not far from the places where the conglomerate is found. the fossils likewise are the fossils of aquatic life. not only this, but they are the fossils of animals which lived in salt water. the presence of salt water, that is, the sea, in this region when the sand of the sandstone was accumulating, makes the wide extent of the formation rational. from the constitution and structure of the sandstone, it is therefore inferred that it accumulated in shallow sea water, and that, in the vicinity of devil's lake, there were land masses (islands) of quartzite which furnished the pebbles and bowlders found in the conglomerate beds at the base of the formation. this being the origin of the sandstone, it is clear that the layers which now appear on opposite sides of valleys must once have been continuous across the depressions; for the sand accumulated in shallow water is never deposited so as to leave valleys between ridges. it is deposited in beds which are continuous over considerable areas. within the area under consideration, limestone is much less widely distributed than sandstone. thin beds of it alternate with layers of sandstone in the upper portion of the potsdam formation, and more massive beds lie above the sandstone on some of the higher elevations of the plain about the quartzite ridge. this is especially true in the southern and southwestern parts of the region shown on plate ii. the limestone immediately overlying the sandstone is the _lower magnesian_ limestone. the beds of limestone, like those of the sandstone beneath, are horizontal or nearly so, and the upper formation lies conformably on the lower. the limestone does not contain water-worn pebbles, and the surfaces of its layers are rarely if ever ripple-marked; yet the arrangement of the rock in distinct layers which carry fossils of marine animals shows that the limestone, like the sandstone beneath, was laid down in the sea. the bearing of this origin of the limestone on the development of the present valleys is the same as that of the sandstone. _origin of the topography._--the topography of the plain surrounding the quartzite ridges, especially that part lying west of devil's lake, is then an erosion topography, developed by running water. its chief characteristic is that every depression leads to a lower one, and that the form of the elevations, hills or ridges, is determined by the valleys. the valleys were made; the hills and ridges left. if the material carried away by the streams could be returned, the valleys would be filled to the level of the ridges which bound them. were this done, the restored surface would be essentially flat. it is the sculpturing of such a plain, chiefly by running water, which has given rise to the present topography. in the development of this topography the more resistant limestone has served as a capping, tending to preserve the hills and ridges. thus many of the hills, especially in the southwest portion of the area shown in plate ii, are found to have caps of the lower magnesian formation. such hills usually have flat tops and steep or even precipitous slopes down to the base of the capping limestone, while the sandstone below, weathering more readily, gives the lower portions of the hills a gentler slope. the elevations of the hills and ridges above the axes of the valleys or, in other words, the relief of the plain is, on the average, about feet, only a few of the more prominent hills exceeding that figure. the topography east of the line between kilbourn city and prairie du sac is not of the unmodified erosion type, as is made evident by marshes, ponds and lakes. the departure from the erosion type is due to a mantle of glacial drift which masks the topography of the bedded rock beneath. its nature, and the topographic modifications which it has produced, will be more fully considered in a later part of this report. [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. iv. the lower narrows of the baraboo from a point on the south range.] ii. the quartzite ridges. _topography._--the south or main quartzite range, about miles in length and one to four miles in width, rises feet to feet above the surrounding sandstone plain. its slopes are generally too steep for cultivation, and are clothed for the most part with a heavy growth of timber, the banks of forest being broken here and there by cultivated fields, or by the purple grey of the rock escarpments too steep for trees to gain a foothold. with the possible exception of the blue mounds southwest of madison, this quartzite range is the most obtrusive topographic feature of southern wisconsin. as approached from the south, one of the striking features of the range is its nearly even crest. extending for miles in an east-west direction, its summit gives a sky-line of long and gentle curves, in which the highest points are but little above the lowest. viewed from the north, the evenness of the crest is not less distinct, but from this side it is seen to be interrupted by a notable break or notch at devil's lake (plates v and xxxvii). the pass across the range makes a right-angled turn in crossing the range, and for this reason is not seen from the south. the north or lesser quartzite range lying north of baraboo is both narrower and lower than the south range, and its crest is frequently interrupted by notches or passes, some of which are wide. near its eastern end occurs the striking gap known as the _lower narrows_ (plate iv) through which the baraboo river escapes to the northward, flowing thence to the wisconsin. at this narrows the quartzite bluffs rise abruptly feet above the river. at a and b, plate ii, there are similar though smaller breaks in the range, also occupied by streams. the connection between the passes and streams is therefore close. there are many small valleys in the sides of the quartzite ranges (especially the south range) which do not extend back to their crests, and therefore do not occasion passes across them. the narrow valleys at a and b in plate xxxvii, known as parfrey's and dorward's glens, respectively, are singularly beautiful gorges, and merit mention as well from the scenic as from the geologic point of view. wider valleys, the heads of which do not reach the crest, occur on the flanks of the main range (as at d and e, plate ii) at many points. one such valley occurs east of the north end of the lake (x, plate xxxvii), another west of the south end (y, plate xxxvii), another on the north face of the west bluff west of the north end of the lake and between the east and west sauk roads, and still others at greater distances from the lake in both directions. it is manifest that if the valleys were extended headward in the direction of their axes, they would interrupt the even crest. many of these valleys, unlike the glens mentioned above, are very wide in proportion to their length. in some of these capacious valleys there are beds of potsdam sandstone, showing that the valleys existed before the sand of the sandstone was deposited. _the structure and constitution of the ridges._--the quartzite of the ridges is nothing more nor less than altered sandstone. its origin dates from that part of geological time known to geologists as the upper huronian period. the popular local belief that the quartzite is of igneous origin is without the slightest warrant. it appears to have had its basis in the notion that devil's lake occupies an extinct volcanic crater. were this the fact, igneous rock should be found about it. quartzite is sandstone in which the intergranular spaces have been filled with silica (quartz) brought in and deposited by percolating water subsequent to the accumulation of the sand. the conversion of sandstone into quartzite is but a continuation of the process which converts sand into sandstone. the potsdam or any other sandstone formation might be converted into quartzite by the same process, and it would then be a _metamorphic_ rock. like the sandstone, the quartzite is in layers. this is perhaps nowhere so distinctly shown on a large scale as in the bluffs at devil's lake, and at the east end of the devil's nose. on the east bluff of the lake, the stratification is most distinctly seen from the middle of the lake, from which point the photograph reproduced in plate vi was taken. [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. v. the notch in the south quartzite range, at devil's lake.] [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. vi. the east bluff of devil's lake, showing the dip of quartzite (to the left), and talus above and below the level where the beds are shown.] unlike the sandstone and limestone, the beds of quartzite are not horizontal. the departure from horizontality, technically known as the _dip_, varies from point to point (fig. ). in the east bluff of the lake as shown in plate vi, the dip is about ° to the north. at the upper and lower narrows of the baraboo (b and c, plate ii) the beds are essentially vertical, that is, they have a dip of about °. between these extremes, many intermediate angles have been noted. plate vii represents a view near ablemans, in the upper narrows, where the nearly vertical beds of quartzite are well exposed. the position of the beds in the quartzite is not always easy of recognition. the difficulty is occasioned by the presence of numerous cleavage planes developed in the rock after its conversion into quartzite. some of these secondary cleavage planes are so regular and so nearly parallel to one another as to be easily confused with the bedding planes. this is especially liable to make determinations of the dip difficult, since the true bedding was often obscured when the cleavage was developed. in spite of the difficulties, the original stratification can usually be determined where there are good exposures of the rock. at some points the surfaces of the layers carry ripple marks, and where they are present, they serve as a ready means of identifying the bedding planes, even though the strata are now on edge. layers of small pebbles are sometimes found. they were horizontal when the sands of the quartzite were accumulating, and where they are found they are sufficient to indicate the original position of the beds. aside from the position of the beds, there is abundant evidence of dynamic action[ ] in the quartzite. along the railway at devil's lake, half a mile south of the cliff house, thin zones of schistose rock may be seen parallel to the bedding planes. these zones of schistose rock a few inches in thickness were developed from the quartzite by the slipping of the rock on either side. this slipping presumably occurred during the adjustment of the heavy beds of quartzite to their new positions, at the time of tilting and folding, for no thick series of rock can be folded without more or less slipping of the layers on one another. the slipping (adjustment) takes place along the weaker zones. such zones of movement are sometimes known as _shear zones_, for the rock on the one side has been sheared (slipped) over that on the other. [ ] irving: "the baraboo quartzite ranges." vol. ii, geology of wisconsin, pp. - . van hise: "some dynamic phenomena shown by the baraboo quartzite ranges of central wisconsin." jour. of geol., vol. i, pp. - . [illustration: fig. .--diagram made by plotting the different dips now at hand along a section from a to b, plate ii, and connecting them so as to show the structure indicated by the known data. the full lines, oblique or vertical, represent the beds of quartzite. the continuous line above them represents the present surface of the quartzite, while the dotted lines suggest the continuation of the beds which completed the great folds of which the present exposures appear to be remnants.] [illustration: fig. .--a diagrammatic section showing the relation of the sandstone to the quartzite.] [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. vii. the east bluff at the upper narrows of the baraboo near ablemans, showing the vertical position of the beds of quartzite. in the lower right-hand corner, above the bridge, appears some breccia.] [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. viii. vertical shear zone in face of east bluff at devil's lake.] near the shear zones parallel to the bedding planes, there is one distinct vertical shear zone (plate viii) three to four feet in width. it is exposed to a height of fully twenty-five feet. along this zone the quartzite has been broken into angular fragments, and at places the crushing of the fragments has produced a "friction clay." slipping along vertical zones would be no necessary part of folding, though it might accompany it. on the other hand, it might have preceded or followed the folding. schistose structure probably does not always denote shearing, at least not the shearing which results from folding. extreme pressure is likely to develop schistosity in rock, the cleavage planes being at right angles to the direction of pressure. it is not always possible to say how far the schistosity of rock at any given point is the result of shear, and how far the result of pressure without shear. schistose structure which does not appear to have resulted from shear, at least not from the shear involved in folding, is well seen in the isolated quartzite mound about four miles southwest of baraboo on the west sauk road (f, plate ii). these quartzite schists are to be looked on as metamorphosed quartzite, just as quartzite is metamorphosed sandstone. at the upper narrows of the baraboo also (b, plate ii), evidence of dynamic action is patent. movement along bedding planes with attendant development of quartz schist has occurred here as at the lake (plate ix). besides the schistose belts, a wide zone of quartzite exposed in the bluffs at this locality has been crushed into angular fragments, and afterwards re-cemented by white quartz deposited from solution by percolating waters (plate x). this quartzite is said to be brecciated. within this zone there are spots where the fragments of quartzite are so well rounded as to simulate water-worn pebbles. their forms appear to be the result of the wear of the fragments on one another during the movements which followed the crushing. conglomerate originating in this way is _friction conglomerate_ or _reibungsbreccia_. the crushing of the rock in this zone probably took place while the beds were being folded; but the brecciated quartzite formed by the re-cementation of the fragments has itself been fractured and broken in such a manner as to show that the formation has suffered at least one dynamic movement since the development of the breccia. that these movements were separated by a considerable interval of time is shown by the fact that the re-cementation of the fragmental products of the first movement preceded the second. what has been said expresses the belief of geologists as to the origin of quartzite and quartz schists; but because of popular misconception on the point it may here be added that neither the changing of the sandstone into quartzite, nor the subsequent transformation of the quartzite to schist, was due primarily to heat. heat was doubtless generated in the mechanical action involved in these changes, but it was subordinate in importance, as it was secondary in origin. igneous rock is associated with the quartzite at a few points. at g and h, plate ii there are considerable masses of porphyry, sustaining such relations to the quartzite as to indicate that they were intruded into the sedimentary beds after the deposition of the latter. [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. ix. a mass of quartzite _in situ_, in the road through the upper narrows near ableman's. the bedding, which is nearly vertical, is indicated by the shading, while the secondary cleavage approaches horizontality.] [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. x. brecciated quartzite near ablemans in the upper narrows. the darker parts are quartzite, the lighter parts the cementing quartz.] iii. relations of the sandstone of the plain to the quartzite of the ridges. the horizontal beds of potsdam sandstone may be traced up to the bases of the quartzite ranges, where they may frequently be seen to abut against the tilted beds of quartzite. not only this, but isolated patches of sandstone lie on the truncated edges of the dipping beds of quartzite well up on the slopes, and even on the crest of the ridge itself. in the former position they may be seen on the east bluff at devil's lake, where horizontal beds of conglomerate and sandstone rest on the layers of quartzite which dip ° to the north. the stratigraphic relations of the two formations are shown in fig. which represents a diagrammatic section from a to b, plate ii. plate xi is reproduced from a photograph taken in the upper narrows of the baraboo near ablemans, and shows the relations as they appear in the field. the quartzite layers are here on edge, and on them rest the horizontal beds of sandstone and conglomerate. similar stratigraphic relations are shown at many other places. this is the relationship of _unconformity_. such an unconformity as that between the sandstone and the quartzite of this region shows the following sequence of events: ( ) the quartzite beds were folded and lifted above the sea in which the sand composing them was originally deposited; ( ) a long period of erosion followed, during which the crests of the folds were worn off; ( ) the land then sank, allowing the sea to again advance over the region; ( ) while the sea was here, sand and gravel derived from the adjacent lands which remained unsubmerged, were deposited on its bottom. these sands became the potsdam sandstone. this sequence of events means that between the deposition of the quartzite and the sandstone, the older formation was disturbed and eroded. either of these events would have produced an unconformity; the two make it more pronounced. that the disturbance of the older formation took place before the later sandstone was deposited is evident from the fact that the latter formation was not involved in the movements which disturbed the former. although the sandstone appears in patches on the quartzite ranges, it is primarily the formation of the surrounding plains, occupying the broad valley between the ranges, and the territory surrounding them. the quartzite, on the other hand, is the formation of the ridges, though it outcrops at a few points in the plain. (compare plates ii and xxxvii.) the striking topographic contrasts between the plains and the ridges is thus seen to be closely related to the rock formations involved. it is the hard and resistant quartzite which forms the ridges, and the less resistant sandstone which forms the lowlands about them. that quartzite underlies the sandstone of the plain is indicated by the occasional outcrops of the former rock on the plain, and from the fact that borings for deep wells have sometimes reached it where it is not exposed. the sandstone of the plain and the quartzite of the ridges are not everywhere exposed. a deep but variable covering of loose material or _mantle rock (drift)_ is found throughout the eastern part of the area, but it does not extend far west of baraboo. this mantle rock is so thick and so irregularly disposed that it has given origin to small hills and ridges. these elevations are superimposed on the erosion topography of the underlying rock, showing that the drift came into the region after the sandstone, limestone, and quartzite had their present relations, and essentially their present topography. further consideration will be given to the drift in a later part of this report. [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xi. the northeast wall of the upper narrows, north of ableman's, showing the horizontal potsdam sandstone and conglomerate lying unconformably on the quartzite, the beds of which are vertical.] part ii. history of the topography. chapter ii. outline of the history of the rock formations which show themselves at the surface. i. the pre-cambrian history of the quartzite. _from loose sand to quartzite._--to understand the geography of a region it is necessary to understand the nature of the materials, the sculpture of which has made the geography. it has already been indicated that the huronian quartzite of which the most prominent elevations of this region are composed, was once loose sand. even at the risk of repetition, the steps in its history are here recounted. the source of the sand was probably the still older rocks of the land in the northern part of wisconsin. brought down to the sea by rivers, or washed from the shores of the land by waves, the sand was deposited in horizontal or nearly horizontal beds at the bottom of the shallow water which then covered central and southern wisconsin. later, perhaps while it was still beneath the sea, the sand was converted into sandstone, the change being effected partly by compression which made the mass of sand more compact, but chiefly by the cementation of its constituent grains into a coherent mass. the water contained in the sand while consolidation was in progress, held in solution some slight amount of silica, the same material of which the grains of sand themselves are composed. little by little this silica in solution was deposited on the surfaces of the sand grains, enlarging them, and at the same time binding them together. thus the sand became sandstone. continued deposition of silica between and around the grains finally filled the interstitial spaces, and when this process was completed, the sandstone had been converted into quartzite. while quartzite is a metamorphic sandstone, it is not to be understood that sandstone cannot be metamorphosed in other ways. _uplift and deformation. dynamic metamorphism._--after the deposition of the sands which later became the quartzite, the beds were uplifted and deformed, as their present positions and relations show. it is not possible to say how far the process of transformation of sand into quartzite was carried while the formation was still beneath the shallow sea in which it was deposited. the sand may have been changed to sandstone, and the sandstone to quartzite, before the sea bottom was converted into land, while on the other hand, the formation may have been in any stage of change from sand to quartzite, when that event occurred. if the process of change was then incomplete, it may have been continued after the sea retired, by the percolating waters derived from the rainfall of the region. either when first converted into land, or at some later time, the beds of rock were folded, and suffered such other changes as attend profound dynamic movements. the conversion of the sandstone into quartzite probably preceded the deformation, since many phenomena indicate that the rock was quartzite and not sandstone when the folding took place. for example, the crushing of the quartzite (now re-cemented into brecciated quartzite) at ablemans probably dates from the orogenic movements which folded the quartzite, and the fractured bits of rock often have corners and edges so sharp as to show that the rock was thoroughly quartzitic when the crushing took place. the uplift and deformation of the beds was probably accomplished slowly, but the vertical and highly tilted strata show that the changes were profound (see fig. ). the dynamic metamorphism which accompanied this profound deformation has already been referred to. the folding of the beds involved the slipping of some on others, and this resulted in the development of quartz schist along the lines of severest movement. changes effected in the texture and structure of the rock under such conditions constitute _dynamic metamorphism_. in general, the metamorphic changes effected by dynamic action are much more profound than those brought about in other ways, and most rocks which have been profoundly metamorphosed, were changed in this way. dynamic action generates heat, but contrary to the popular notion, the heat involved in profound metamorphism is usually secondary, and the dynamic action fundamental. at the same time that quartz schist was locally developed from the quartzite, crushing probably occurred in other places. this is _demorphism_, rather than metamorphism. _erosion of the quartzite._--when the huronian beds were raised to the estate of land, the processes of erosion immediately began to work on them. the heat and the cold, the plants and the animals, the winds, and especially the rain and the water which came from the melting of the snow, produced their appropriate effects. under the influence of these agencies the surface of the rock was loosened by weathering, valleys were cut in it by running water, and wear and degradation went on at all points. the antagonistic processes of uplift and degradation went on for unnumbered centuries, long enough for even the slow processes involved to effect stupendous results. degradation was continuous after the region became land, though uplift may not have been. on the whole, elevation exceeded degradation, for some parts of the quartzite finally came to stand high above the level of the sea,--the level to which all degradation tends. fig. conveys some notion of the amount of rock which was removed from the quartzite folds about baraboo during this long period of erosion. the south range would seem to represent the stub of one side of a great anticlinal fold, a large part of which (represented by the dotted lines) was carried away, while the north range may be the core of another fold, now exposed by erosion. some idea of the geography of the quartzite at the close of this period of erosion may be gained by imagining the work of later times undone. the younger beds covering the quartzite of the plains have a thickness varying from zero to several hundred feet, and effectually mask the irregularities of the surface of the subjacent quartzite. could they be removed, the topography of the quartzite would be disclosed, and found to have much greater relief than the present surface; that is, the vertical distance between the crest of the quartzite ridge, and the surface of the quartzite under the surrounding lowlands, would be greater than that between the same crest and the surface of the sandstone. but even this does not give the full measure of the relief of the quartzite at the close of the long period of erosion which followed its uplift, for allowance must be made for the amount of erosion which the crests of the quartzite ranges have suffered since that time. the present surface therefore does not give an adequate conception of the irregularity of the surface at the close of the period of erosion which followed the uplift and deformation of the quartzite. so high were the crests of the quartzite ranges above their surroundings at that time, that they may well be thought of as mountainous. from this point of view, the quartzite ranges of today are the partially buried mountains of the pre-potsdam land of south central wisconsin. when the extreme hardness of the quartzite is remembered and also the extent of the erosion which affected it (fig. ) before the next succeeding formation was deposited, it is safe to conclude that the period of erosion was very long. _thickness of the quartzite._--the thickness of the quartzite is not known, even approximately. the great thickness in the south range suggested by the diagram (fig. ) may perhaps be an exaggeration. faulting which has not been discovered may have occurred, causing repetition of beds at the surface (fig. ), and so an exaggerated appearance of thickness. after all allowances have been made, it is still evident that the thickness of the quartzite is very great. ii. the history of the paleozoic strata. _the subsidence._--following the long period of erosion, the irregular and almost mountainous area of central wisconsin was depressed sufficiently to submerge large areas which had been land. the subsidence was probably slow, and as the sea advanced from the south, it covered first the valleys and lowlands, and later the lower hills and ridges, while the higher hills and ridges of the quartzite stood as islands in the rising sea. still later, the highest ridges of the region were themselves probably submerged. [illustration: fig. .--a diagrammatic cross-section, showing how, by faulting, the apparent thickness of the quartzite would be increased.] _the potsdam sandstone (and conglomerate)._--so soon as the sea began to overspread the region, its bottom became the site of deposition, and the deposition continued as long as the submergence lasted. it is to the sediments deposited during the earlier part of this submergence that the name _potsdam_ is given. the sources of the sediments are not far to seek. as the former land was depressed beneath the sea, its surface was doubtless covered with the products of rock decay, consisting of earths, sands, small bits and larger masses of quartzite. these materials, or at least the finer parts, were handled by the waves of the shallow waters, for they were at first shallow, and assorted and re-distributed. thus the residuary products on the submerged surface, were one source of sediments. from the shores also, so long as land areas remained, the waves derived sediments. these were composed in part of the weathered products of the rock, and in part of the undecomposed rock against which the waves beat, after the loose materials had been worn away. these sediments derived from the shore were shifted, and finally mingled with those derived from the submerged surface. so long as any part of the older land remained above the water, its streams brought sediments to the sea. these also were shifted by the waves and shore currents, and finally deposited with the others on the eroded surface of the quartzite. thus sediments derived in various ways, but inherently essentially similar, entered into the new formation. [illustration: fig. .--diagram to illustrate the theoretical disposition of sediments about an island.] [illustration: fig. .--same as fig. , except that the land has been depressed.] the first material to be deposited on the surface of the quartzite as it was submerged, was the coarsest part of the sediment. of the sediment derived by the waves from the coasts, and brought down to the sea by rivers, the coarsest would at each stage be left nearest the shore, while the finer was carried progressively farther and farther from it. thus at each stage the sand was deposited farther from the shore than the gravel, and the mud farther than the sand, where the water was so deep that the bottom was subject to little agitation by waves. the theoretical distribution of sediments about an island as it was depressed, is illustrated by the following diagrams, figs. and . it will be seen that the surface of the quartzite is immediately overlain by conglomerate, but that the conglomerate near its top is younger than that near its base. in conformity with this natural distribution of sediments, the basal beds of the potsdam formation are often conglomeratic (fig. , plate iii, fig. , and plate xxv). this may oftenest be seen near the quartzite ridges, for here only is the base of the formation commonly exposed. the pebbles and larger masses of the conglomerate are quartzite, like that of the subjacent beds, and demonstrate the source of at least some of the material of the younger formation. that the pebbles and bowlders are of quartzite is significant, for it shows that the older formation had been changed from sandstone to quartzite, before the deposition of the potsdam sediments. the sand associated with the pebbles may well have come from the breaking up of the quartzite, though some of it may have been washed in from other sources by the waters in which the deposition took place. [illustration: fig. .--sketch showing relation of basal potsdam conglomerate and sandstone to the quartzite, on the east bluff at devil's lake, behind the cliff house.] the basal conglomerate may be seen at many places, but nowhere about devil's lake is it so well exposed as at parfrey's glen (a, plate xxxvii), where the rounded stones of which it is composed vary from pebbles, the size of a pea, to bowlders more than three feet in diameter. other localities where the conglomerates may be seen to advantage are dorward's glen (b, plate xxxvii), the east bluff at devil's lake just above the cliff house, and at the upper narrows of the baraboo, above ablemans. while the base of the potsdam is conglomeratic in many places, the main body of it is so generally sandstone that the formation as a whole is commonly known as the potsdam sandstone. the first effect of the sedimentation which followed submergence was to even up the irregular surface of the quartzite, for the depressions in the surface were the first to be submerged, and the first to be filled. as the body of sediment thickened, it buried the lower hills and the lower parts of the higher ones. the extent to which the potsdam formation buried the main ridge may never be known. it may have buried it completely, for as already stated patches of sandstone are found upon the main range. these patches make it clear that some formation younger than the quartzite once covered essentially all of the higher ridge. other evidence to be adduced later, confirms this conclusion. it has, however, not been demonstrated that the high-level patches of sandstone are potsdam. there is abundant evidence that the subsidence which let the potsdam seas in over the eroded surface of the huronian quartzite was gradual. one line of evidence is found in the cross-bedding of the sandstone (plate xii) especially well exhibited in the dalles of the wisconsin. the beds of sandstone are essentially horizontal, but within the horizontal beds there are often secondary layers which depart many degrees from horizontality, the maximum being about °. plates xxvii and xii give a better idea of the structure here referred to than verbal description can. the explanation of cross-bedding is to be found in the varying conditions under which sand was deposited. cross-bedding denotes shallow water, where waves and shore currents were effective at the bottom where deposition is in progress. for a time, beds were deposited off shore at a certain angle, much as in the building of a delta (fig. ). then by subsidence of the bottom, other layers with like structure were deposited over the first. by this sequence of events, the dip of the secondary layers should be toward the open water, and in this region their dip is generally to the south. at any stage of deposition the waves engendered by storms were liable to erode the surface of the deposits already made, and new layers, discordant with those below, were likely to be laid down upon them. the subordinate layers of each deposit might dip in any direction. if this process were repeated many times during the submergence, the existing complexity would be explained. [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xii. steamboat rock,--an island in the dalles of the wisconsin.] [illustration: fig. .--a diagrammatic cross-section of a delta.] the maximum known thickness of the potsdam sandstone in wisconsin is about , feet, but its thickness in this region is much less. where not capped by some younger formation, its upper surface has suffered extensive erosion, and the present thickness therefore falls short of the original. the figures given above may not be too great for the latter. _the lower magnesian limestone._--the conditions of sedimentation finally changed in the area under consideration. when the sand of the sandstone was being deposited, adjacent lands were the source whence the sediments were chiefly derived. the evidence that the region was sinking while the sand was being deposited shows that the land masses which were supplying the sand, were becoming progressively smaller. ultimately the sand ceased to be washed out to the region here described, either because the water became too deep[ ] or because the source of supply was too distant. when these relations were brought about, the conditions were favorable for the deposition of sediments which were to become limestone. these sediments consisted chiefly of the shells of marine life, together with an unknown amount of lime carbonate precipitated from the waters of the sea. the limestone contains no coarse, and but little fine material derived from the land, and the surfaces of its layers are rarely if ever ripple-marked. the materials of which it is made must therefore have been laid down in quiet waters which were essentially free from land-derived sediments. the depth of the water in which it was deposited was not, however, great, for the fossils are not the remains of animals which lived in abysmal depths. [ ] a few hundred feet would suffice. the deposition of limestone sediments following the deposition of the potsdam sands, does not necessarily mean that there was more or different marine life while the younger formation was making, but only that the shells, etc., which before had been mingled with the sand, making fossiliferous sandstone, were now accumulated essentially free from land-derived sediment, and therefore made limestone. like the sandstone beneath, the limestone formation has a wide distribution outside the area here under discussion, showing that conditions similar to those of central wisconsin were widely distributed at this time. the beds of limestone are conformable on those of the sandstone, and the conformable relations of the two formations indicate that the deposition of the upper followed that of the lower, without interruption. the thickness of the lower magnesian limestone varies from less than to more than feet, but in this region its thickness is nearer the lesser figure than the larger. the limestone is now present only in the eastern and southern parts of the area, though it originally covered the whole area. _the st. peters sandstone._--overlying the lower magnesian limestone at a few points, are seen remnants of st. peters sandstone. the constitution of this formation shows that conditions of sedimentation had again changed, so that sand was again deposited where the conditions had been favorable to the deposition of limestone but a short time before. this formation has been recognized at but two places (d and e) within the area shown on plate xxxvii, but the relations at these two points are such as to lead to the conclusion that the formation may once have covered the entire region. this sandstone formation is very like the sandstone below. its materials doubtless came from the lands which then existed. the formation is relatively thin, ranging from somewhat below to somewhat above feet. the change from the deposition of limestone sediments to sand may well have resulted from the shoaling of the waters, which allowed the sand to be carried farther from shore. rise of the land may have accompanied the shoaling of the waters, and the higher lands would have furnished more and coarser sediments to the sea. _younger beds._--that formations younger than the st. peters sandstone once overlaid this part of wisconsin is almost certain, though no remnants of them now exist. evidence which cannot be here detailed[ ] indicates that sedimentation about the quartzite ridges went on not only until the irregularities of surface were evened up, but until even the highest peaks of the quartzite were buried, and that formations as high in the series as the niagara limestone once overlay their crests. before this condition was reached, the quartzite ridges had of course ceased to be islands, and at the same time had ceased to be a source of supply of sediments. the aggregate thickness of the paleozoic beds in the region, as first deposited, was probably not less than , feet, and it may have been much more. this thickness would have buried the crests of the quartzite ridges under several hundred feet of sediment (see fig. ). [ ] jour. of geol., vol. iii (pp. - ). [illustration: fig. .--the geological formations of southern wisconsin in the order of their occurrence. not all of these are found about devil's lake.] it is by no means certain that south central wisconsin was continuously submerged while this thick series of beds was being deposited. indeed, there is good reason to believe that there was at least one period of emergence, followed, after a considerable lapse of time, by re-submergence and renewed deposition, before the paleozoic series of the region was complete. these movements, however, had little effect on the geography of the region. finally the long period of submergence, during which several changes in sedimentation had taken place, came to an end, and the area under discussion was again converted into land. _time involved._--though it cannot be reduced to numerical terms, the time involved in the deposition of these several formations of the paleozoic must have been very long. it is probably to be reckoned in millions of years, rather than in denominations of a lower order. _climatic conditions._--little is known concerning the climate of this long period of sedimentation. theoretical considerations have usually been thought to lead to the conclusion that the climate during this part of the earth's history was uniform, moist, and warm; but the conclusion seems not to be so well founded as to command great confidence. _the uplift._--after sedimentation had proceeded to some such extent as indicated, the sea again retired from central wisconsin. this may have been because the sea bottom of this region rose, or because the sea bottom in other places was depressed, thus drawing off the water. the topography of this new land, like the topography of those portions of the sea bottom which are similarly situated, must have been for the most part level. low swells and broad undulations may have existed, but no considerable prominences, and no sudden change of slope. the surface was probably so flat that it would have been regarded as a level surface had it been seen. the height to which the uplift carried the new land surface at the outset must ever remain a matter of conjecture. some estimate may be made of the amount of uplift which the region has suffered since the beginning of this uplift, but it is unknown how much took place at this time, and how much in later periods of geological history. the new land surface at once became the site of new activities. all processes of land erosion at once attacked the new surface, in the effort to carry its materials back to the sea. the sculpturing of this plain, which, with some interruption, has continued to the present day, has given the region the chief elements of its present topography. but before considering the special history of erosion in this region, it may be well to consider briefly the general principles and processes of land degradation. chapter iii. general outline of rain and river erosion. _elements of erosion._--the general process of subaerial erosion is divisible into the several sub-processes of weathering, transportation, and corrasion.[ ] [ ] there is an admirable exposition of this subject in gilbert's "henry mountains." _weathering_ is the term applied to all those processes which disintegrate and disrupt exposed surfaces of rock. it is accomplished chiefly by solution, changes in temperature, the wedge-work of ice and roots, the borings of animals, and such chemical changes as surface water and air effect. the products of weathering are transported by the direct action of gravity, by glaciers, by winds, and by running water. of these the last is the most important. _corrasion_ is accomplished chiefly by the mechanical wear of streams, aided by the hard fragments such as sand, gravel and bowlders, which they carry. the solution effected by the waters of a stream may also be regarded as a part of corrasion. under ordinary circumstances solution by streams is relatively unimportant, but where the rock is relatively soluble, and where conditions are not favorable for abrasion, solution may be more important than mechanical wear. so soon as sea bottom is raised to the estate of land, it is attacked by the several processes of degradation. the processes of weathering at once begin to loosen the material of the surface if it be solid; winds shift the finer particles about, and with the first shower transportation by running water begins. weathering prepares the material for transportation and transportation leads to corrasion. since the goal of all material transported by running water is the sea, subaerial erosion means degradation of the surface. _erosion without valleys._--in the work of degradation the valley becomes the site of greatest activity, and in the following pages especial attention is given to the development of valleys and to the phases of topography to which their development leads. if a new land surface were to come into existence, composed of materials which were perfectly homogeneous, with slopes of absolute uniformity in all directions, and if the rain, the winds and all other surface agencies acted uniformly over the entire area, valleys would not be developed. that portion of the rainfall which was not evaporated and did not sink beneath the surface, would flow off the land in a sheet. the wear which it would effect would be equal in all directions from the center. if the angle of the slope were constant from center to shore, or if it increased shoreward, the wear effected by this sheet of water would be greatest at the shore, because here the sheet of flowing water would be deepest and swiftest, and therefore most effective in corrasion. _the beginning of a valley._--but land masses as we know them do not have equal and uniform slopes to the sea in all directions, nor is the material over any considerable area perfectly homogeneous. departure from these conditions, even in the smallest degree, would lead to very different results. that the surface of newly emerged land masses would, as a rule, not be rough, is evident from the fact that the bottom of the sea is usually rather smooth. much of it indeed is so nearly plane that if the water were withdrawn, the eye would scarcely detect any departure from planeness. the topography of a land mass newly exposed either by its own elevation or by the withdrawal of the sea, would ordinarily be similar to that which would exist in the vicinity of necedah and east of camp douglas, if the few lone hills were removed, and the very shallow valleys filled. though such a surface would seem to be moderately uniform as to its slopes, and homogeneous as to its material, neither the uniformity nor the homogeneity are perfect, and the rain water would not run off in sheets, and the wear would not be equal at all points. let it be supposed that an area of shallow sea bottom is raised above the sea, and that the elevation proceeds until the land has an altitude of several hundred feet. so soon as it appears above the sea, the rain falling upon it begins to modify its surface. some of the water evaporates at once, and has little effect on the surface; some of it sinks beneath the surface and finds its way underground to the sea; and some of it runs off over the surface and performs the work characteristic of streams. so far as concerns modifications of the surface, the run-off is the most important part. the run-off of the surface would tend to gather in the depressions of the surface, however slight they may be. this tendency is shown on almost every hillside during and after a considerable shower. the water concentrated in the depressions is in excess of that flowing over other parts of the surface, and therefore flows faster. flowing faster, it erodes the surface over which it flows more rapidly, and as a result the initial depressions are deepened, and _washes_ or _gullies_ are started. should the run-off not find irregularities of slope, it would, at the outset, fail of concentration; but should it find the material more easily eroded along certain lines than along others, the lines of easier wear would become the sites of greater erosion. this would lead to the development of gullies, that is, to irregularities of slope. either inequality of slope or material may therefore determine the location of a gully, and one of these conditions is indispensable. once started, each wash or gully becomes the cause of its own growth, for the gully developed by the water of one shower, determines greater concentration of water during the next. greater concentration means faster flow, faster flow means more rapid wear, and this means corresponding enlargement of the depression through which the flow takes place. the enlargement effected by successive showers affects a gully in all dimensions. the water coming in at its head carries the head back into the land (head erosion), thus lengthening the gully; the water coming in at its sides wears back the lateral slopes, thus widening it; and the water flowing along its bottom deepens it. thus gullies grow to be ravines, and farther enlargement by the same processes converts ravines into valleys. a river valley therefore is often but a gully grown big. [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xiii. fig. . a very young valley. illustration: fig. . a valley in a later stage of development. illustration: fig. . young valleys.] _the course of a valley._--in the lengthening of a gully or valley headward, the growth will be in the direction of greatest wear. thus in plate xiii, fig. , if the water coming in at the head of the gully effects most wear in the direction a, the head of the gully will advance in that direction; if there be most wear in the direction b or c, the head will advance toward one of these points. the direction of greatest wear will be determined either by the slope of the surface, or by the nature of the surface material. the slope may lead to the concentration of the entering waters along one line, and the surface material may be less resistant in one direction than in another. if these factors favor the same direction of head-growth, the lengthening will be more rapid than if but one is favorable. if there be more rapid growth along two lines, as b and c, plate xiii, fig. , than between them, two gullies may develop (plate xiii, fig. ). the frequent and tortuous windings common to ravines and valleys are therefore to be explained by the inequalities of slope or material which affected the surface while the valley was developing. _tributary valleys._--following out this simple conception of valley growth, we have to inquire how a valley system (a main valley and its tributaries) is developed. the conditions which determine the location and development of gullies in a new land surface, determine the location and development of tributary gullies. in flowing over the lateral slopes of a gully or ravine, the water finds either slope or surface material failing of uniformity. both conditions lead to the concentration of the water along certain lines, and concentration of flow on the slope of an erosion depression, be it valley or gully, leads to the development of a tributary depression. in its growth, the tributary repeats, in all essential respects, the history of its main. it is lengthened headward by water coming in at its upper end, is widened by side wash, and deepened by the downward cutting of the water which flows along its axis. the factors controlling its development are the same as those which controlled the valley to which it is tributary. there is one peculiarity of the courses of tributaries which deserves mention. tributaries, as a rule, join their mains with an acute angle up stream. in general, new land surfaces, such as are now under consideration, slope toward the sea. if a tributary gully were to start back from its main at right angles, more water would come in on the side away from the shore, on account of the seaward slope of the land. this would be true of the head of the gully as well as of other portions, and the effect would be to turn the head more and more toward parallelism with the main valley. local irregularities of surface may, and frequently do, interfere with these normal relations, so that the general course of a tributary is occasionally at right angles to its main. still more rarely does the general course of a tributary make an acute angle with its main on the down stream side. local irregularities of surface determine the windings of a tributary, so that their courses for longer or shorter distances may be in violation of the general rule (c, fig. ); but on the whole, the valleys of a system whose history has not been interrupted in a region where the surface material is not notably heterogeneous, follow the course indicated above. this is shown by nearly every drainage system on the atlantic coastal plain which represents more nearly than any other portion of our continent, the conditions here under consideration. fig. represents the drainage system of the mullica river in southern new jersey and is a type of the coastal plain river system. _how a valley gets a stream._--valleys may become somewhat deep and long and wide without possessing permanent streams, though from their inception they have _temporary_ streams, the water for which is furnished by showers or melting snow. yet sooner or later, valleys come to have permanent streams. how are they acquired? does the valley find the stream or the stream the valley? for the answer to these questions, a brief digression will be helpful. [illustration: fig. .--a typical river system of the coastal plain type.] in cultivated regions, wells are of frequent occurrence. in a flat region of uniform structure, the depth at which well water may be obtained is essentially constant at all points. if holes (wells and , fig. ) be excavated below this level, water seeps into them, and in a series of wells the water stands at a nearly common level. this means that the sub-structure is full of water up to that level. these relations are illustrated by fig. . the diagram represents a vertical section through a flat region from the surface (s s) down below the bottom of wells. the water stands at the same level in the two cells ( and ), and the plane through them, at the surface of the water, is the _ground water level_. if in such a surface a valley were to be cut until its bottom was below the ground water level, the water would seep into it, as it does into the wells; and if the amount were sufficient, a permanent stream would be established. this is illustrated in fig. . the line a a represents the ground water level, and the level at which the water stands in the wells, under ordinary circumstances. the bottom of the valley is below the level of the ground water, and the water seeps into it from either side. its tendency is to fill the valley to the level a a. but instead of accumulating in the open valley as it does in the enclosed wells, it flows away, and the ground water level on either hand is drawn down. [illustration: fig. .--diagram illustrating the relations of ground water to streams.] the level of the ground water fluctuates. it is depressed when the season is dry (a' a'), and raised when precipitation is abundant (a'' a''). when it is raised, the water in the wells rises, and the stream in the valley is swollen. when it falls, the ground water surface is depressed, and the water in the wells becomes lower. if the water surface sinks below the bottom of the wells, the wells "go dry;" if below the bottom of the valley, the valley becomes for the time being, a "dry run." when a well is below the lowest ground-water level its supply of water never fails, and when the valley is sufficiently below the same level, its stream does not cease to flow, even in periods of drought. on account of the free evaporation in the open valley, the valley depression must be somewhat below the level necessary for a well, in order that the flow may be constant. it will be seen that _intermittent_ streams, that is, streams which flow in wet seasons and fail in dry, are intermediate between streams which flow after showers only, and those which flow without interruption. in the figure the stream would become dry if the ground water level sank to a' a'. it is to be noted that a permanent stream does not normally precede its valley, but that the valley, developed through gully-hood and ravine-hood to valley-hood by means of the temporary streams supplied by the run-off of occasional showers, _finds a stream_, just as diggers of wells find water. the case is not altered if the stream be fed by springs, for the valley finds the spring, as truly as the well-digger finds a "vein" of water. _limits of a valley._--so soon as a valley acquires a permanent stream, its development goes on without the interruption to which it was subject while the stream was intermittent. the permanent stream, like the temporary one which preceded it, tends to deepen and widen its valley, and, under certain conditions, to lengthen it as well. the means by which these enlargements are affected are the same as before. there are limits, however, in length, depth, and width, beyond which a valley may not go. no stream can cut below the level of the water into which it flows, and it can cut to that level only at its outlet. up stream from that point, a gentle gradient will be established over which the water will flow without cutting. in this condition the stream is _at grade_. its channel has reached _baselevel_, that is, the level to which the stream can wear its bed. this grade is, however, not necessarily permanent, for what was baselevel for a small stream in an early stage of its development, is not necessarily baselevel for the larger stream which succeeds it at a later time. weathering, wash, and lateral corrasion of the stream continue to widen the valley after it has reached baselevel. the bluffs of valleys are thus forced to recede, and the valley is widened at the expense of the upland. two valleys widening on opposite sides of a divide, narrow the divide between them, and may ultimately wear it out. when this is accomplished, the two valleys become one. the limit to which a valley may widen on either side is therefore its neighboring valley, and since, after two valleys have become one by the elimination of the ridge between them, there are still valleys on either hand, the final result of the widening of all valleys must be to reduce all the area which they drain to baselevel. as this process goes forward, the upper flat into which the valleys were cut is being restricted in area, while the lower flats developed by the streams in the valley bottoms are being enlarged. thus the lower flats grow at the expense of the higher. there are also limits in length which a valley may not exceed. the head of any valley may recede until some other valley is reached. the recession may not stop even there, for if, on opposite sides of a divide, erosion is unequal, as between a and b, fig. , the divide will be moved toward the side of less rapid erosion, and it will cease to recede only when erosion on the two sides becomes equal ( a and b). in homogeneous material this will be when the slopes on the two sides are equal. [illustration: fig. .--diagram showing the shifting of a divide. the slopes a and b are unequal. the steeper slope is worn more rapidly and the divide is shifted from to , where the two slopes become equal and the migration of the divide ceases.] it should be noted that the lengthening of a valley headward is not normally the work of the permanent stream, for the permanent stream begins some distance below the head of the valley. at the head, therefore, erosion goes on as at the beginning, even after a permanent stream is acquired. under certain circumstances, the valley may be lengthened at its debouchure. if the detritus carried by it is deposited at its mouth, or if the sea bottom beyond that point rise, the land may be extended seaward, and over this extension the stream will find its way. thus at their lower, as well as at their upper ends, both the stream and its valley may be lengthened. _a cycle of erosion._--if, along the borders of a new-born land mass, a series of valleys were developed, essentially parallel to one another, they would constitute depressions separated by elevations, representing the original surface not yet notably affected by erosion (see plate xiv, fig. ). these inter-valley areas might at first be wide or narrow, but in process of time they would necessarily become narrow, for, once, a valley is started, all the water which enters it from either side helps to wear back its slopes, and the wearing back of the slopes means the widening of the valleys on the one hand and the narrowing of the inter-valley ridges on the other. not only would the water running over the slopes of a valley wear back its walls, but many other processes conspire to the same end. the wetting and drying, the freezing and the thawing, the roots of plants and the borings of animals, all tend to loosen the material on the slopes or walls of the valleys, and gravity helps the loosened material to descend. once in the valley bottom, the running water is likely to carry it off, landing it finally in the sea. thus the growth of the valley is not the result of running water alone, though this is the most important single factor in the process. [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xiv. fig. . the same valleys as shown in plate xiii, fig. , in a later stage of development. illustration: fig. . same valleys as shown in fig. , in a still later stage of development.] even if valleys developed no tributaries, they would, in the course of time, widen to such an extent as to nearly obliterate the intervening ridges. the surface, however, would not easily be reduced to perfect flatness. for a long time at least there would remain something of slope from the central axis of the former inter-stream ridge, toward the streams on either hand; but if the process of erosion went on for a sufficiently long period of time, the inter-stream ridge would be brought very low, and the result would be an essentially flat surface between the streams, much below the level of the old one. the first valleys which started on the land surface (see plate xiii, fig. ) would be almost sure to develop numerous tributaries. into tributary valleys water would flow from their sides and from their heads, and as a result they would widen and deepen and lengthen just as their mains had done before them. by lengthening headward they would work back from their mains some part, or even all of the way across the divides separating the main valleys. by this process, the tributaries cut the divides between the main streams into shorter cross-ridges. with the development of tributary valleys there would be many lines of drainage instead of two, working at the area between two main streams. the result would be that the surface would be brought low much more rapidly, for it is clear that many valleys within the area between the main streams, widening at the same time, would diminish the aggregate area of the upland much more rapidly than two alone could do. the same thing is made clear in another way. it will be seen (plate xiv, figs. and ) that the tributaries would presently dissect an area of uniform surface, tending to cut it into a series of short ridges or hills. in this way the amount of sloping surface is greatly increased, and as a result, every shower would have much more effect in washing loose materials down to lower levels, whence the streams could carry them to the sea. [illustration: fig. .--cross-sections showing various stages of erosion in one cycle.] the successive stages in the process of lowering a surface are suggested by fig. , which represents a series of cross-sections of a land mass in process of degradation. the uppermost section represents a level surface crossed by young valleys. the next lower represents the same surface at a later stage, when the valleys have grown larger, while the third and succeeding sections represent still later stages in the process of degradation. plate xiii, fig. , and plate xiv, figs. and , represent in another way the successive stages of stream work in the general process of degradation. [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xv. diagram illustrating how a hard inclined layer of rock becomes a ridge in the process of degradation.] in this manner a series of rivers, operating for a sufficiently long period of time, might reduce even a high land mass to a low level, scarcely above the sea. the new level would be developed soonest near the sea, and the areas farthest from it would be the last--other things being equal--to be brought low. the time necessary for the development of such a surface is known as a _cycle of erosion_, and the resulting surface is a _base-level plain_, that is, a plain as near sea level as river erosion can bring it. at a stage shortly preceding the base-level stage the surface would be a _peneplain_. a peneplain, therefore, is a surface which has been brought toward, but not to base-level. land surfaces are often spoken of as young or old in their erosion history according to the stage of advancement which has been made toward base-leveling. thus the colorado canyon, deep and impressive as it is, is, in terms of erosion, a young valley, for the river has done but a small part of the work which must be done in order to bring its basin to baselevel. _effects of unequal hardness._--the process of erosion thus sketched would ultimately bring the surface of the land down to base-level, and in case the material of the land were homogeneous, the last points to be reduced would be those most remote from the axes of the streams doing the work of leveling. but if the material of the land were of unequal hardness, those parts which were hardest would resist the action of erosion most effectively. the areas of softer rock would be brought low, and the outcrops of hard rock (plate xv) would constitute ridges during the later stages of an erosion cycle. if there were bodies of hard rock, such as the baraboo quartzite, surrounded by sandstone, such as the potsdam, the sandstone on either hand would be worn down much more readily than the quartzite, and in the course of degradation the latter would come to stand out prominently. the region in the vicinity of devil's lake is in that stage of erosion in which the quartzite ridges are conspicuous (plate xxxvii). the less resistant sandstone has been removed from about them, and erosion has not advanced so far since the isolation of the quartzite ridges as to greatly lower their crests. the harder strata are at a level where surface water can still work effectively, even though slowly, upon them, and in spite of their great resistance they will ultimately be brought down to the common level. it will be seen that, from the point of view of subaerial erosion, a base-level plain is the only land surface which is in a condition of approximate stability. _falls and rapids._--if in lowering its channel a stream crosses one layer of rock much harder than the next underlying, the deepening will go on more rapidly on the less resistant bed. where the stream crosses from the harder to the less hard, the gradient is likely to become steep, and a rapids is formed. these conditions are suggested in fig. which represents the successive profiles (a b, a c, d e, f e, g e, and h e) of a stream crossing from a harder to a softer formation. below the point a the stream is flowing over rock which is easily eroded, while above that point its course is over a harder formation. just below a (profile a b) the gradient has become so steep that there are rapids. under these conditions, erosion is rapid just beyond the crossing of the hard layer, and the gradient becomes higher and higher. when the steep slope of the rapids approaches verticality, the rapids become a _fall_ (profile a c). [illustration: fig. .--diagram to illustrate the development of a rapid and fall. the upper layer is harder than the strata below. the successive profiles of the stream below the hard layer are represented by the lines a b, a c, d e, f e, g e, and h e.] as the water falls over the precipitous face and strikes upon the softer rock below, part of it rebounds against the base of the vertical face (fig. ). the result of wear at this point is the undermining of the hard layer above, and sooner or later, portions of it will fall. this will occasion the recession of the fall (profile d e and f e). as the fall recedes, it grows less and less high. when the recession has reached the point i, or, in other words, when the gradient of the stream below the fall crosses the junction of the beds of unequal hardness, as it ultimately must, effective undermining ceases, and the end of the fall is at hand. [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xvi. skillett falls, in the potsdam formation, three miles southwest of baraboo. the several small falls are occasioned by slight inequalities in the hardness of the layers.] when the effective undercutting ceases because the softer bed is no longer accessible, the point of maximum wear is transferred to the top of the hard bed just where the water begins to fall (g, fig. ). the wear here is no greater than before, though it is greater relatively. the relatively greater wear at this point destroys the verticality of the face, converting it into a steep slope. when this happens, the fall is a thing of the past, and rapids succeed. with continued flow the bed of the rapids becomes less and less steep, until it is finally reduced to the normal gradient of the stream (h e), when the rapids disappear. when thin layers of rock in a stream's course vary in hardness, softer beds alternating with harder ones, a series of falls such as shown in plate xvi, may result. as they work up stream, these falls will be obliterated one by one. thus it is seen that falls and rapids are not permanent features of the landscape. they belong to the younger period of a valley's history, rather than to the older. they are marks of topographic youth. _narrows._--where a stream crosses a hard layer or ridge of rock lying between softer ones, the valley will not widen so rapidly in the hard rock as above and below. if the hard beds be vertical, so that their outcrop is not shifted as the degradation of the surface proceeds, a notable constriction of the valley results. such a constriction is a _narrows_. the upper and lower narrows of the baraboo (plate iv) are good examples of the effect of hard rock on the widening of a valley. _erosion of folded strata._--the processes of river erosion would not be essentially different in case the land mass upon which erosion operated were made of tilted and folded strata. the folds would, at the outset, determine the position of the drainage lines, for the main streams would flow in the troughs (synclines) between the folds (anticlines). once developed, the streams would lower their beds, widen their valleys, and lengthen their courses, and in the long process of time they would bring the area drained nearly to sea-level, just as in the preceding case. it was under such conditions that the general processes of subaerial erosion operated in south central wisconsin, after the uplift of the quartzite and before the deposition of the potsdam sandstone. it was then that the principal features of the topography of the quartzite were developed. in regions of folded strata, certain beds are likely to be more resistant than others. where harder beds alternate with softer, the former finally come to stand out as ridges, while the outcrops of the latter mark the sites of the valleys. such alternations of beds of unequal resistance give rise to various peculiarities of drainage, particularly in the courses of tributaries. these peculiarities find no illustration in this region and are not here discussed. _base-level plains and peneplains._--it is important to notice that a plane surface (base-level) developed by streams could only be developed at elevations but slightly above the sea, that is, at levels at which running water ceases to be an effective agent of erosion; for so long as a stream is actively deepening its valley, its tendency is to roughen the area which it drains, not to make it smooth. the colorado river, flowing through high land, makes a deep gorge. all the streams of the western plateaus have deep valleys, and the manifest result of their action is to roughen the surface; but given time enough, and the streams will have cut their beds to low gradients. then, though deepening of the valleys will cease, widening will not, and inch by inch and shower by shower the elevated lands between the valleys will be reduced in area, and ultimately the whole will be brought down nearly to the level of the stream beds. this is illustrated by fig. . [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xvii. a group of mounds on the plain southwest from camp douglas. the base-level surface is well shown, and above it rise the remnants of the higher plain from which the lower was reduced.] [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xviii. castle rock near camp douglas. in this view the relation of the erosion remnant to the extensive base-leveled surface is well shown.] it is important to notice further that if the original surface on which erosion began is level, there is no stage intermediate between the beginning and the end of an erosion cycle, when the surface is again level, or nearly so, though in the stage of a cycle next preceding the last--the peneplain stage (fourth profile, fig. )--the surface approaches flatness. it is also important to notice that when streams have cut a land surface down to the level at which they cease to erode, that surface will still possess some slight slope, and that to seaward. no definite degree of slope can be fixed upon as marking a base-level. the angle of slope which would practically stop erosion in a region of slight rainfall would be great enough to allow of erosion if the precipitation were greater. all that can be said, therefore, is that the angle of slope must be low. the mississippi has a fall of less than a foot per mile for some hundreds of miles above the gulf. a small stream in a similar situation would have ceased to lower its channel before so low a gradient was reached. the nearest approach to a base-leveled region within the area here under consideration is in the vicinity of camp douglas and necedah (see plate i). this is indeed one of the best examples of a base-leveled plain known. here the broad plain, extending in some directions as far as the eye can reach, is as low as it could be reduced by the streams which developed it. the erosion cycle which produced the plain was, however, not completed, for above the plain rise a few conspicuous hills (plates xvii and xviii, and fig. ), and to the west of it lie the highlands marking the level from which the low plain was reduced. where a region has been clearly base-leveled, isolated masses or ridges of resistant rock may still stand out conspicuously above it. the quartzite hill at necedah is an example. such hills are known as _monadnocks_. this name was taken from mount monadnock which owes its origin to the removal of the surrounding less resistant beds. the name has now become generic. many of the isolated hills on the peneplain east of camp douglas are perhaps due to superior resistance, though the rock of which they are composed belongs to the same formation as that which has been removed. [illustration: fig. .--sketch, looking northwest from camp douglas.] characteristics of valleys at various stages of development. in the early stages of its development a depression made by erosion has steep lateral slopes, the exact character of which is determined by many considerations. its normal cross-section is usually described as v-shaped (fig. ). in the early stages of its development, especially if in unconsolidated material, the slopes are normally convex inward. if cut in solid rock, the cross section may be the same, though many variations are likely to appear, due especially to the structure of the rock and to inequalities of hardness. if a stream be swift enough to carry off not only all the detritus descending from its slopes, but to abrade its bed effectively besides, a steep-sided gorge develops. if it becomes deep, it is a canyon. for the development of a canyon, the material of the walls must be such as is capable of standing at a high angle. a canyon always indicates that the down-cutting of a stream keeps well ahead of the widening. [illustration: fig. .--diagrammatic cross-section of a young valley.] of young valleys in loose material (drift) there are many examples in the eastern portion of the area here described. shallow canyons or gorges in rock are also found. the gorge of skillett creek at and above the pewit's nest about three miles southwest from baraboo, the gorge of dell creek two miles south of kilbourn city, and the dalles of the wisconsin at kilbourn city may serve as illustrations of this type of valley. [illustration: fig. .--diagrammatic profile of a young valley.] the profile of a valley at the stage of its development corresponding to the above section is represented diagrammatically by the curve a b in fig. . the sketch (pl. xix, fig. ) represents a bird's-eye view of a valley in the same stage of development. [illustration: fig. .--diagrammatic cross-section of a valley at a stage corresponding with that shown in plate xix, fig. .] at a stage of development later than that represented by the v-shaped cross-section, the corresponding section is u-shaped, as shown in fig. . the same form is sketched in plate xix, fig. . this represents a stage of development where detritus descending the slopes is not all carried away by the stream, and where the valley is being widened faster than it is deepened. its slopes are therefore becoming gentler. the profile of the valley at this stage would be much the same as that in the preceding, except that the gradient in the lower portion would be lower. still later the cross section of the valley assumes the shape shown in fig. , and in perspective the form sketched in plate xx, fig. . this transformation is effected partly by erosion, and partly by deposition in the valley. when a stream has cut its valley as low as conditions allow, it becomes sluggish. a sluggish stream is easily turned from side to side, and, directed against its banks, it may undercut them, causing them to recede at the point of undercutting. in its meanderings, it undercuts at various points at various times, and the aggregate result is the widening of the valley. by this process alone the stream would develop a flat grade. at the same time all the drainage which comes in at the sides tends to carry the walls of the valley farther from its axis. [illustration: fig. .--diagrammatic cross-section of a valley at a stage later than that shown in fig. .] a sluggish stream is also generally a depositing stream. its deposits tend to aggrade (build up) the flat which its meanderings develop. when a valley bottom is built up, it becomes wider at the same time, for the valley is, as a rule, wider at any given level than at any lower one. thus the u-shaped valley is finally converted into a valley with a flat bottom, the flat being due in large part to erosion, and in smaller part to deposition. under exceptional circumstances the relative importance of these two factors may be reversed. it will be seen that the cross-section of a valley affords a clue to its age. a valley without a flat is young, and increasing age is indicated by increasing width. valleys illustrating all stages of development are to be found in the devil's lake region. the valley of honey creek southwest of devil's lake may be taken as an illustration of a valley at an intermediate stage of development, while examples of old valleys are found in the flat country about camp douglas and necedah. [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xix. fig. . sketch of a valley at the stage of development corresponding to the cross section shown in fig. . illustration: fig. . sketch of a valley at the stage of development corresponding to the cross section shown in fig. .] [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xx. fig. . sketch of a part of a valley at the stage of development corresponding to the cross section shown in fig . illustration: fig. . sketch of a section of the baraboo valley.] _transportation and deposition._ sediment is carried by streams in two ways: ( ) by being rolled along the bottom, and ( ) by being held in suspension. dissolved mineral matter (which is not sediment) is also carried in the water. by means of that rolled along the bottom and carried in suspension, especially the former, the stream as already stated abrades its bed. the transporting power of a stream of given size varies with its velocity. increase in the declivity or the volume of a stream increases its velocity and therefore its transportive power. the transportation effected by a stream is influenced ( ) by its transporting power, and ( ) by the size and amount of material available for carriage. fine material is carried with a less expenditure of energy than an equal amount of coarse. with the same expenditure of energy therefore a stream can carry a greater amount of the former than of the latter. since the transportation effected by a stream is dependent on its gradient, its size, and the size and amount of material available, it follows that when these conditions change so as to decrease the carrying power of the river, deposition will follow, if the stream was previously fully loaded. in other words, a stream will deposit when it becomes overloaded. overloading may come about in the following ways: ( ) by decrease in gradient, checking velocity and therefore carrying power; ( ) by decrease in amount of water, which may result from evaporation, absorption, etc.; ( ) by change in the shape of the channel, so that the friction of flow is increased, and therefore the force available for transportation lessened; ( ) by lateral drainage bringing in more sediment than the main stream can carry; ( ) by change in the character of the material to which the stream has access; for if it becomes finer, the coarse material previously carried will be dropped, and the fine taken; and ( ) by the checking of velocity when a stream flows into a body of standing water. _topographic forms resulting from stream deposition._--the topographic forms resulting from stream deposition are various. at the bottoms of steep slopes, temporary streams build _alluvial cones_ or _fans_. along its flood-plain portion, a stream deposits more or less sediment on its flats. the part played by deposition in building a river flat has already been alluded to. a depositing stream often wanders about in an apparently aimless way across its flood plain. at the bends in its course, cutting is often taking place on the outside of a curve while deposition is going on in the inside. the valley of the baraboo illustrates this process of cutting and building. fig. , plate xx, is based upon the features of the valley within the city of baraboo. besides depositing on its flood-plain, a stream often deposits in its channel. any obstruction of a channel which checks the current of a loaded stream occasions deposition. in this way "bars" are formed. once started, the bar increases in size, for it becomes an obstacle to flow, and so the cause of its own growth. it may be built up nearly to the surface of the stream, and in low water, it may become an island by the depression of the surface water. in some parts of its course, as about merrimac, the wisconsin river is marked by such islands at low water, and by a much larger number of bars. at their debouchures, streams give up their loads of sediment. under favorable conditions deltas are built, but delta-building has not entered into the physical history of this region to any notable extent. _rejuvenation of streams._ after the development of a base-level plain, its surface would suffer little change (except that effected by underground water) so long as it maintained its position. but if, after its development, a base-level plain were elevated, the old surface in a new position would be subject to a new series of changes identical in kind with those which had gone before. the elevation would give the established streams greater fall, and they would reassume the characteristics of youth. the greater fall would accelerate their velocities; the increased velocities would entail increased erosion; increased erosion would result in the deepening of the valleys, and the deepening of the valleys would lead to the roughening of the surface. but in the course of time, the _rejuvenated_ streams would have cut their valleys as low as the new altitude of the land permitted, that is, to a new base-level. the process of deepening would then stop, and the limit of vertical relief which the streams were capable of developing, would be attained. but the valleys would not stop widening when they stopped deepening, and as they widened, the intervening divides would become narrower, and ultimately lower. in the course of time they would be destroyed, giving rise to a new level surface much below the old one, but developed in the same position which the old one occupied when it originated; that is, a position but little above sea level. if at some intermediate stage in the development of a second base-level plain, say at a time when the streams, rejuvenated by uplift, had brought half the elevated surface down to a new base-level, another uplift were to occur, the half completed cycle would be brought to an end, and a new one begun. the streams would again be quickened, and as a result they would promptly cut new and deeper channels in the bottoms of the great valleys which had already been developed. the topography which would result is suggested by the following diagram (fig. ) which illustrates the cross-section which would be found after the following sequence of events: ( ) the development of a base-level, a a; ( ) uplift, rejuvenation of the streams, and a new cycle of erosion half completed, the new base-level being at b b; ( ) a second uplift, bringing the second (incomplete) cycle of erosion to a close, and by rejuvenating the streams, inaugurating the third cycle. as represented in the diagram, the third cycle has not progressed far, being represented only by the narrow valley c. the base-level is now - , and the valley represented in the diagram has not yet reached it. [illustration: fig. .--diagram (cross-section), illustrating the topographic effect of rejuvenation by uplift.] [illustration: fig. .--normal profile of a valley bottom in a non-mountainous region.] the rejuvenation of a stream shows itself in another way. the normal profile of a valley bottom in a non-mountainous region is a gentle curve, concave upward with gradient increasing from debouchure to source. such a profile is shown in fig. . fig. , on the other hand, is the profile of a rejuvenated stream. the valley once had a profile similar to that shown in fig. . below b its former continuation is marked by the dotted line b c. since rejuvenation the stream has deepened the lower part of its valley, and established there a profile in harmony with the new conditions. the upper end of the new curve has not yet reached beyond b. [illustration: fig. .--profile of a stream rejuvenated by uplift.] _underground water._ in what has preceded, reference has been made only to the results accomplished by the water which runs off over the surface. the water which sinks beneath it is, however, of no small importance in reducing a land surface. the enormous amount of mineral matter in solution in spring water bears witness to the efficiency of the ground water in dissolving rock, for since the water did not contain the mineral matter when it entered the soil, it must have acquired it below the surface. by this means alone, areas of more soluble rock are lowered below those of less solubility. furthermore, the water is still active as a solvent agent after a surface has been reduced to so low a gradient that the run-off ceases to erode mechanically. chapter iv. erosion and the development of striking scenic features. the uplift following the period of paleozoic deposition in south central wisconsin, inaugurated a period of erosion which, with some interruptions, has continued to the present day. the processes of weathering began as soon as the surface was exposed to the weather, and corrasion by running water began with the first shower which fell upon it. the sediment worn from the land was carried back to the sea, there to be used in the building of still younger formations. the rate of erosion of a land surface depends in large measure upon its height. as a rule, it is eroded rapidly if high, and but slowly if low. it is not known whether the lands of central wisconsin rose to slight or to great heights at the close of the period of paleozoic sedimentation. it is therefore not known whether the erosion was at the outset rapid or slow. if the land of southern wisconsin remained low for a time after the uplift which brought the paleozoic sedimentation to a close, weathering would have exceeded transportation and corrasion. a large proportion of the rainfall would have sunk beneath the surface, and found its way to the sea by subterranean routes. loosening of material by alternate wetting and drying, expansion and contraction, freezing and thawing, and by solution, might have gone on steadily, but so long as the land was low, there would have been little run-off, and that little would have flowed over a surface of gentle slopes, and transportation would have been at a minimum. on the whole, the degradation of the land under these conditions could not have advanced rapidly. if, on the other hand, the land was raised promptly to a considerable height, erosion would have been vigorous at the outset. the surface waters would soon have developed valleys which the streams would have widened, deepened and lengthened. both transportation and corrasion would have been active, and whatever material was prepared for transportation by weathering, and brought into the valleys by side-wash, would have been hurried on its way to the sea, and degradation would have proceeded rapidly. _establishment of drainage._--valleys were developed in this new land surface according to the principles already set forth. between the valleys there were divides, which became higher as the valleys became deeper, and narrower as the valleys widened. ultimately the ridges were lowered, and many of them finally eliminated in the manner already outlined. the distance below the original surface and that at which the first series of new flats were developed is conjectural, but it would have depended on the height of the land. so far as can now be inferred, the new base-plain toward which the streams cut may have been or feet below the crests of the quartzite ridges. it was at this level that the oldest base-plain of which this immediate region shows evidence, was developed. had the quartzite ranges not been completely buried by the paleozoic sediments, they would have appeared as ridges on the new land surface, and would have had a marked influence on the development of the drainage of the newly emerged surface. but as the ranges were probably completely buried, the drainage lines were established regardless of the position of the hard, but buried ridges. when in the process of degradation the quartzite surfaces were reached, the streams encountered a formation far more resistant than the surrounding sandstone and limestone. as the less resistant strata were worn away, the old quartzite ridges, long buried, again became prominent topographic features. in this condition they were "resurrected mountains." if, when erosion on the uplifted surface of paleozoic rocks began, a valley had been located directly over the buried quartzite ridge, and along its course, it would have been deepened normally until its bottom reached the crest of the hard formation. then, instead of sinking its valley vertically downward into the quartzite, the stream would have shifted its channel down the slope of the range along the junction of the softer and harder rock (fig. ). such changes occasioned by the nature and position of the rock concerned, are known as _adjustments_. [illustration: fig. .--diagram illustrating the hypothetical case of a stream working down the slope of the quartzite range. the successive sections of the valley are suggested by the lines ae, be, ce and de.] streams which crossed the quartzite ridges on the overlying strata might have held their courses even after their valleys were lowered to the level of the quartzite. such streams would have developed narrows at the crossing of the quartzite. in so far as there were passes in the quartzite range before the deposition of the paleozoic beds, they were filled during the long period of sedimentation, to be again cleared out during the subsequent period of erosion. the gap in the south range now occupied by the lake was a narrows in a valley which existed, though perhaps not to its present depth, before the potsdam sandstone was deposited. it was filled when the sediments of that formation were laid down, to be again opened, and perhaps deepened, in the period of erosion which followed the deposition of the paleozoic series. during the earliest period of erosion of which there is positive evidence, after the uplift of the paleozoic beds, the softer formations about the quartzite were worn down to a level or feet below the crests of the south quartzite range. at this lower level, an approximate plain, a peneplain, was developed, the level of which is shown by numerous hills, the summits of which now reach an elevation of from , to , feet above the sea. at the time of its development, this peneplain was but little above sea level, for this is the only elevation at which running water can develop such a plain. above the general level of this plain rose the quartzite ranges as elongate monadnocks, the highest parts of which were fully feet above the plain. a few other points in the vicinity failed to be reduced to the level of the peneplain. the , foot hill (d, plate xxxvii), one and one-half miles southeast of the lower narrows, and gibraltar rock (e, same plate), two miles southeast of merrimac, rose as prominences above it. it is possible that these crests are remnants of a base-level plain older than that referred to above. if while the quartzite remained much as now, the valleys in the sandstone below , or , feet were filled, the result would correspond in a general way to the surface which existed in this region when the first distinctly recognizable cycle of erosion was brought to a close. above the undulating plain developed in the sandstone and limestone, the main quartzite ridge would have risen as a conspicuous ridge to feet. this cycle had not been completed, that is, the work of base-leveling had not been altogether accomplished, when the peneplain was elevated, and the cycle, though still incomplete, brought to a close. by the uplift, the streams were rejuvenated, and sunk their valleys into the elevated peneplain. thus a new cycle of erosion was begun, and the uplifted peneplain was dissected by the quickened streams which sank their valleys promptly into the slightly resistant sandstone. at their new base-level, they ultimately developed new flats. this cycle of erosion appears to have advanced no farther than to the development of wide flats along the principal streams, such as the wisconsin and the baraboo, and narrow ones along the subordinate water courses, when it was interrupted. along the main streams the new flats were at a level which is now from to feet above the sea, and to feet below the south quartzite range. it was at this time that the plains about camp douglas and necedah, already referred to, were developed. during this second incomplete cycle, the quartzite ranges, resisting erosion, came to stand up still more prominently than during the first. the interruption of this cycle was caused by the advent of the glacial period which disturbed the normal course of erosion. this period was accompanied and followed by slight changes of level which also had their influence on the streams. the consideration of the effects of glaciation and of subsequent river erosion are postponed, but it may be stated that within the area which was glaciated the post-glacial streams have been largely occupied in removing the drift deposited by the ice from the preglacial valleys, or in cutting new valleys in the drift. the streams outside the area of glaciation were less seriously disturbed. at levels other than those indicated, partial base-levels are suggested, and although less well marked in this region, they might, in the study of a broader area, bring out a much more complicated erosion history. as already suggested, one cycle may have preceded that the remnants of which now stand , - , feet above sea level, and another may have intervened between this and that marked by the to foot level. from the foregoing it is clear that the topography of the region is, on the whole, an erosion topography, save for certain details in its eastern portion. the valleys differ in form and in size, with their age, and with the nature of the material in which they are cut; while the hills and ridges differ with varying relations to the streams, and with the nature of the material of which they are composed. _striking scenic features._ in a region so devoid of striking scenery as the central portion of the mississippi basin, topographic features which would be passed without special notice in regions of greater relief, become the objects of interest. but in south central wisconsin there are various features which would attract attention in any region where the scenery is not mountainous. [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xxi. cleopatra's needle. west bluff of devil's lake.] [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xxii. turk's head. west bluff of devil's lake.] [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xxiii. devil's doorway. east of devil's lake.] on the bluffs at devil's lake there are many minor features which are sure to attract the attention of visitors. such are "cleopatra's needle" (plate xxi), "turk's head" (plate xxii), and the "devil's doorway" (plate xxiii). these particular forms have resulted from the peculiar weathering of the quartzite. the rock is affected by several systems of vertical or nearly vertical joint planes (cracks), which divide the whole formation into a series of vertical columns. there are also horizontal and oblique planes of cleavage dividing the columns, so that the great quartzite pile may be said to be made up of a series of blocks, which are generally in contact with one another. the isolated pillars and columns which have received special names have been left as they now stand by the falling away of the blocks which once surrounded them. they themselves must soon follow. the great talus slopes at the base of the bluffs, such as those on the west side of the lake and on the east bluff near its southeast corner, plate xxiv, are silent witnesses of the extent to which this process has already gone. the blocks of rock of which they are composed have been loosened by freezing water, by the roots of trees, and by expansion and contraction due to changing temperature, and have fallen from their former positions to those they now occupy. their descent, effected by gravity directly, is, it will be noted, the first step in their journey to the sea, the final resting place of all products of land degradation. _the baraboo bluffs._--nowhere in southern wisconsin, or indeed in a large area adjacent to it, are there elevations which so nearly approach mountains as the ranges of quartzite in the vicinity of baraboo and devil's lake. so much has already been said of their history that there is need for little further description. plate iv gives some idea of the appearance of the ranges. the history of the ranges, already outlined, involves the following stages: ( ) the deposition of the sands in huronian time; ( ) the change of the sand to sandstone and the sandstone to quartzite; ( ) the uplift and deformation of the beds; ( ) igneous intrusions, faulting, crushing, and shoaring, with the development of schists accompanying the deformation; ( ) a prolonged period of erosion during which the folds of quartzite were largely worn away, though considerable ridges, the huronian mountains of early cambrian times, still remained high above their surroundings; ( ) the submergence of the region, finally involving even the crests of the ridges of quartzite; ( ) a protracted period of deposition during which the potsdam sandstone and several later paleozoic formations were laid down about, and finally over, the quartzite, burying the mountainous ridges; ( ) the elevation of the paleozoic sea-bottom, converting it into land; ( ) a long period of erosion, during which the upper paleozoic beds were removed, and the quartzite re-discovered. being much harder than the paleozoic rocks, the quartzite ridges again came to stand out as prominent ridges, as the surrounding beds of relatively slight resistance were worn away. they are "resurrected" mountains, though not with the full height which they had in pre-cambrian time, for they are still partially buried by younger beds. _the narrows in the quartzite._--there are four narrows or passes in the quartzite ridges, all of which are rather striking features. one of them is in the south range, one in the north range near its eastern end, while the others are in an isolated area of quartzite at ablemans which is really a continuation of the north range. two of these narrows are occupied by the baraboo river, one by narrows creek, and the fourth by devil's lake. from ablemans to a point several miles east of baraboo, the baraboo river flows through a capacious valley. where it crosses the north range, six miles or more north of east of baraboo, the broad valley is abruptly constricted to a narrow pass with precipitous sides, about feet high (c, plate xxxvii). this constriction is the lower narrows, conspicuous from many points on the south range, and from the plains to the north. beyond the quartzite, the valley again opens out into a broad flat. [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xxiv. talus slope on the east bluff of devil's lake.] seen from a distance, the narrows has the appearance of an abrupt notch in the high ridge (plate iv). seen at closer range, the gap is still more impressive. it is in striking contrast with the other narrows in that there are no talus accumulations at the bases of the steep slopes, and in that the slopes are relatively smooth and altogether free from the curious details of sculpture seen in the other gaps where the slopes are equally steep. the upper narrows of the baraboo at ablemans (b, plate ii) is in some ways similar to the lower, though less conspicuous because less deep. its slopes are more rugged, and piles of talus lie at their bases as at devil's lake. this narrows also differs from the lower in that the quartzite on one side is covered with potsdam conglomerate, which overlies the truncated edges of the vertical layers of quartzite with unconformable contact. so clear an example of unconformity is not often seen. potsdam sandstone is also seen to rest against the quartzite on either side of the narrows (fig. ), thus emphasizing the unconformity. the beauty and interest of this narrows is enhanced by the quartzite breccia ( which appears on its walls. [illustration: fig. .--a generalized diagrammatic cross-section at the upper narrows, to show the relation of the sandstone to the quartzite.] one and one-half miles west of ablemans (a, plate ii) is the third pass in the north quartzite ridge. this pass is narrower than the others, and is occupied by narrows creek. its walls are nearly vertical and possess the same rugged beauty as those at ablemans. as at the upper narrows, the beds of quartzite here are essentially vertical. they are indeed the continuation of the beds exposed at that place. the fourth narrows is across the south range (i, plate ii). it is not now occupied by a stream, though like the others it was cut by a stream, which was afterwards shut out from it. because of its depth, feet, and the ruggedness of its slopes, and because of its occupancy by the lake, this pass is the center of interest for the whole region. so much has already been said concerning it in other portions of this report that further description is here omitted. the manner in which the pass was robbed of its stream will be discussed later. the history of these several narrows, up to the time of the glacial period may now be summarized. since remnants of potsdam sandstone are found in some of them, it is clear that they existed in pre-cambrian time,[ ] and there is no reason to doubt that they are the work of the streams of those ancient days, working as streams now work. following the pre-cambrian period of erosion during which the notches were cut, came the submergence of the region, and the gaps were filled with sand and gravel, and finally the ridges themselves were buried. uplift and a second period of erosion followed, during which the quartzite ranges were again exposed by the removal of the beds which overlay them, and the narrows cleaned out and deepened, and again occupied by streams. this condition of things lasted up to the time when the ice invaded the region. [ ] it is not here asserted that these notches were as deep as now, in pre-cambrian time. it is, however, certain that the quartzite was deeply eroded, previous to the deposition of the potsdam sandstone. _glens._--no enumeration of the special scenic features of this region would be complete without mention of parfrey's and dorward's glens (a and b, plate xxxvii, and plate xxv). attention has already been directed to them as illustrations of young valleys, and as places where the potsdam conglomerate is well shown, but they are attractive from the scenic point of view. their frequent mention in earlier parts of this report makes further reference to them at this point unnecessary. [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xxv. in dorward's glen. the basal conglomerate of the potsdam formation is shown at the lower right-hand corner, and is overlain by sandstone. (photograph furnished by mr. wilfred dorward).] [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xxvi. natural bridge near denzer.] [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xxvii. navy yard. dalles of the wisconsin.] pine hollow (k, plate ii) is another attractive gorge on the south flank of the greater quartzite range. the rock at this point is especially well exposed. this gorge is beyond the drift-covered portion of the range, and therefore dates from the pre-glacial time. the pewit's nest, about three miles southwest of baraboo (m, plate ii), is another point of interest. above the "nest," skillett creek flows through a narrow and picturesque gorge in the potsdam sandstone. the origin of this gorge is explained elsewhere. _natural bridge._--about two miles north and a little west of the village of denzer (sec. , t. n., r. e.), is a small natural bridge, which has resulted from the unequal weathering of the sandstone (see plate xxvi). the "bridge" is curious, rather than beautiful or impressive. _the dalles of the wisconsin._--the _dalles_ is the term applied to a narrow canyon-like stretch of the wisconsin valley seven miles in length, near kilbourn city (see frontispiece). the depth of the gorge is from to feet. the part above the bridge at kilbourn city is the "upper dalles;" that below, the "lower dalles." within this stretch of the valley are perhaps the most picturesque features of the region. the sides of the gorge are nearly vertical much of the way, and at many points are so steep on both sides that landing would be impossible. between these sandstone walls flows the deep and swift wisconsin river. such a rock gorge is in itself a thing of beauty, but in the dalles there are many minor features which enhance the charm of the whole. one of the features which deserves especial mention is the peculiar crenate form of the walls at the banks of the river. this is perhaps best seen in that part of the dalles known as the "navy yard." plate xxvii. the sandstone is affected by a series of vertical cracks or joints. from weathering, the rock along these joints becomes softened, and the running water wears the softened rock at the joint planes more readily than other parts of its bank, and so develops a reëntrant at these points. rain water descending to the river finds and follows the joint planes, and thus widens the cracks. as a result of stream and rain and weathering, deep reëntrant angles are produced. the projections between are rounded off so that the banks of the stream have assumed the crenate form shown in plate xxviii, and frontispiece. when this process of weathering at the joints is carried sufficiently far, columns of rock become isolated, and stand out on the river bluffs as "chimneys" (plate xxviii). at a still later stage of development, decay of the rock along the joint planes may leave a large mass of rock completely isolated. "steamboat rock" (plate xii) and "sugar bowl" (plate xxix) are examples of islands thus formed. the walls of sandstone weather in a peculiar manner at some points in the lower dalles, as shown on plate xxx. the little ridges stand out because they are harder and resist weathering better than the other parts. this is due in part at least to the presence of iron in the more resistant portions, cementing them more firmly. in the process of segregation, cementing materials are often distributed unequally. the effect of differences in hardness on erosion is also shown on a larger scale and in other ways. perhaps the most striking illustration is _stand rock_ (plate xxxi), but most of the innumerable and picturesque irregularities on the rock walls are to be accounted for by such differences. minor valleys tributary to the wisconsin, such as _witch's gulch_ and _cold water canyon_ deserve mention, both because of their beauty, and because they illustrate a type of erosion at an early stage of valley development. in character they are comparable to the larger gorge to which they are tributary. in the downward cutting, which far exceeds the side wear in these tributary canyons, the water has excavated large bowl or jug-like forms. in witch's gulch such forms are now being excavated. they are developed just below falls, where the water carrying debris, eddies, and the jugs or pot-holes are the result of the wear effected by the eddies. the "devil's jug" and many similar hollows are thus explained. [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xxviii. chimney rock. dalles of the wisconsin. cross-bedding well shown in foreground near bottom.] [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xxix. an island in the lower dalles.] [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xxx. view in lower dalles showing peculiar honeycomb weathering.] _the mounds and castle rocks._--in the vicinity of camp douglas and over a large area to the east, are still other striking topographic forms, which owe their origin to different conditions, though they were fashioned by the same forces. here there are many "tower" or "castle" rocks, which rise to heights varying from to feet above the surrounding plain. they are remnants of beds which were once continuous over the low lands above which the hills now rise. in plates xvii and xviii the general character of these hills is shown. the rock of which they are composed is potsdam sandstone, the same formation which underlies most of the area about baraboo. the effect of the vertical joints and of horizontal layers of unequal hardness is well shown. rains, winds, frosts, and roots are still working to compass the destruction of these picturesque hills, and the talus of sand bordering the "castle" is a reminder of the fate which awaits them. these hills are the more conspicuous and the more instructive since the plain out of which they rise is so flat. it is indeed one of the best examples of a base-level plain to be found on the continent. the crests of these hills reach an elevation of between , and , feet. they appear to correspond with the level of the first peneplain recognized in the devil's lake region. it was in the second cycle of erosion, when their surroundings were brought down to the new base-level, that these hills were left. west of camp douglas, there are still higher elevations, which seem to match gibraltar rock. the friendship "mounds" north of kilbourn city, the castellated hills a few miles northwest of the same place, and petenwell peak on the banks of the wisconsin (plate xxxii), are further examples of the same class of hills. all are of potsdam sandstone. in addition to the "castle" rocks and base-level plain about camp douglas, other features should be mentioned. no other portion of the area touched upon in this report affords such fine examples of the different types of erosion topography. in the base-level plain are found "old-age" valleys, broad and shallow, with the stream meandering in a wide flood-plain. traveling up such a valley, the topography becomes younger and younger, and the various stages mentioned earlier in the text, and suggested in plate xix, figs. and , and plate xx, fig. , are here illustrated. [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xxxi. stand rock. upper end of the upper dalles.] [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xxxii. petenwell peak.] chapter v. the glacial period. the eastern part of the area with which this report deals, is covered with a mantle of drift which, as already pointed out, has greatly modified the details of its topography. to the consideration of the drift and its history attention is now turned. _the drift._--the drift consists of a body of clay, sand, gravel and bowlders, spread out as a cover of unequal thickness over the rock formations beneath. these various classes of material may be confusedly commingled, or they may be more or less distinctly separated from one another. when commingled, all may be in approximately equal proportions, or any one may predominate over any or all the others to any extent. it was long since recognized that the materials of the drift did not originate where they now lie, and that, in consequence, they sustain no genetic relationship to the strata on which they rest. long before the drift received any special attention from geologists, it was well known that it had been transported from some other locality to that where it now occurs. the early conception was that it had been drifted into its present position from some outside source by water. it was this conception of its origin which gave it the name of _drift_. it is now known that the drift was deposited by glacier ice and the waters which arose from its melting, but the old name is still retained. clearly to understand the origin of the drift, and the method by which it attained its present distribution, it may be well to consider some elementary facts and principles concerning climate and its effects, even at the risk of repeating what is already familiar. _snow fields and ice sheets._--the temperature and the snowfall of a region may stand in such a relation to each other that the summer's heat may barely suffice to melt the winter's snow. if under these circumstances the annual temperature were to be reduced, or the fall of snow increased, the summer's heat would fail to melt all the winter's snow, and some portion of it would endure through the summer, and through successive summers, constituting a perennial snow-field. were this process once inaugurated, the depth of the snow would increase from year to year. the area of the snow-field would be extended at the same time, since the snow-field would so far reduce the surrounding temperature as to increase the proportion of the annual precipitation which fell as snow. in the course of time, and under favorable conditions, the area of the snow-field would attain great dimensions, and the depth of the snow would become very great. as in the case of existing snow fields the lower part of the snow mass would eventually be converted into ice. several factors would conspire to this end. . the pressure of the overlying snow would tend to compress the lower portion, and snow rendered sufficiently compact by compression would be regarded as ice. . water arising from the melting of the surface snow by the sun's heat, would percolate through the superficial layers of snow, and, freezing below, take the form of ice. . on standing, even without pressure or partial melting, snow appears to undergo changes of crystallization which render it more compact. in these and perhaps other ways, a snow-field becomes an ice-field, the snow being restricted to its surface. eventually the increase in the depth of the snow and ice in a snow-field will give rise to new phenomena. let a snow and ice field be assumed in which the depth of snow and ice is greatest at the center, with diminution toward its edges. the field of snow, if resting on a level base, would have some such cross-section as that represented in the diagram, fig. . when the thickness of the ice has become considerable, it is evident that the pressure upon its lower and marginal parts will be great. we are wont to think of ice as a brittle solid. if in its place there were some plastic substance which would yield to pressure, the weight of the ice would cause the marginal parts to extend themselves in all directions by a sort of flowing motion. [illustration: fig. .--diagrammatic cross-section of a field of ice and snow (c) resting on a level base a-b.] under great pressure, many substances which otherwise appear to be solid, exhibit the characteristics of plastic bodies. among the substances exhibiting this property, ice is perhaps best known. brittle and resistant as it seems, it may yet be molded into almost any desirable form if subjected to sufficient pressure, steadily applied through long intervals of time. the changes of form thus produced in ice are brought about without visible fracture. concerning the exact nature of the movement, physicists are not agreed; but the result appears to be essentially such as would be brought about if the ice were capable of flowing, with extreme slowness, under great pressure continuously applied. in the assumed ice-field, there are the conditions for great pressure and for its continuous application. if the ice be capable of moving as a plastic body, the weight of the ice would induce gradual movement outward from the center of the field, so that the area surrounding the region where the snow accumulated would gradually be encroached upon by the spreading of the ice. observation shows that this is what takes place in every snow-field of sufficient depth. motion thus brought about is glacier motion, and ice thus moving is glacier ice. once in motion, two factors would determine the limit to which the ice would extend itself: ( ) the rate at which it advances; and ( ) the rate at which the advancing edge is wasted. the rate of advance would depend upon several conditions, one of which, in all cases, would be the pressure of the ice which started and which perpetuates the motion. if the pressure be increased the ice will advance more rapidly, and if it advance more rapidly, it will advance farther before it is melted. other things remaining constant, therefore, increase of pressure will cause the ice-sheet to extend itself farther from the center of motion. increase of snowfall will increase the pressure of the snow and ice field by increasing its mass. if, therefore, the precipitation over a given snow-field be increased for a period of years, the ice-sheet's marginal motion will be accelerated, and its area enlarged. a decrease of precipitation, taken in connection with unchanged wastage would decrease the pressure of the ice and retard its movement. if, while the rate of advance diminished, the rate of wastage remained constant, the edge of the ice would recede, and the snow and ice field be contracted. the rate at which the edge of the advancing ice is wasted depends largely on the climate. if, while the rate of advance remains constant, the climate becomes warmer, melting will be more rapid, and the ratio between melting and advance will be increased. the edge of the ice will therefore recede. the same result will follow, if, while temperature remains constant, the atmosphere becomes drier, since this will increase wastage by evaporation. were the climate to become warmer and drier at the same time, the rate of recession of the ice would be greater than if but one of these changes occurred. if, on the other hand, the temperature over and about the ice field be lowered, melting will be diminished, and if the rate of movement be constant, the edge of the ice will advance farther than under the earlier conditions of temperature, since it has more time to advance before it is melted. an increase in the humidity of the atmosphere, while the temperature remains constant, will produce the same result, since increased humidity of the atmosphere diminishes evaporation. a decrease of temperature, decreasing the melting, and an increase of humidity, decreasing the evaporation, would cause the ice to advance farther than either change alone, since both changes decrease the wastage. if, at the same time that conditions so change as to increase the rate of movement of the ice, climatic conditions so change as to reduce the rate of waste, the advance of the ice before it is melted will be greater than where only one set of conditions is altered. if, instead of favoring advance, the two series of conditions conspire to cause the ice to recede, the recession will likewise be greater than when but one set of conditions is favorable thereto. greenland affords an example of the conditions here described. a large part of the half million or more square miles which this body of land is estimated to contain, is covered by a vast sheet of snow and ice, thousands of feet in thickness. in this field of snow and ice, there is continuous though slow movement. the ice creeps slowly toward the borders of the island, advancing until it reaches a position where the climate is such as to waste (melt and evaporate) it as rapidly as it advances. the edge of the ice does not remain fixed in position. there is reason to believe that it alternately advances and retreats as the ratio between movement and waste increases or decreases. these oscillations in position are doubtless connected with climatic changes. when the ice edge retreats, it may be because the waste is increased, or because the snowfall is decreased, or both. in any case, when the ice edge recedes from the coast, it tends to recede until its edge reaches a position where the melting is less rapid than in its former position, and where the advance is counterbalanced by the waste. this represents a condition of equilibrium so far as the edge of the ice is concerned, and here the edge of the ice would remain so long as the conditions were unchanged. when for a period of years the rate of melting of the ice is diminished, or the snowfall increased, or both, the ice edge advances to a new line where melting is more rapid than at its former edge. the edge of the ice would tend to reach a position where waste and advance balance. here its advance would cease, and here its edge would remain so long as climatic conditions were unchanged. if the conditions determining melting and flowage be continually changing, the ice edge will not find a position of equilibrium, but will advance when the conditions are favorable for advance, and retreat when the conditions are reversed. not only the edge of the ice in greenland, but the ends of existing mountain glaciers as well, are subject to fluctuation, and are delicate indices of variations in the climate of the regions where they occur. _the north american ice sheet._--in an area north of the eastern part of the united states and in another west of hudson bay it is believed that ice sheets similar to that which now covers greenland began to accumulate at the beginning of the glacial period. from these areas as centers, the ice spread in all directions, partly as the result of accumulation, and partly as the result of movement induced by the weight of the ice itself. the ice sheets spreading from these centers came together south of hudson's bay, and invaded the territory of the united states as a single sheet, which, at the time of its greatest development, covered a large part of our country (plate xxxiii), its area being known by the extent of the drift which it left behind when it was melted. in the east, it buried the whole of new england, most of new york, and the northern parts of new jersey and pennsylvania. farther west, the southern margin of the ice crossed the ohio river in the vicinity of cincinnati, and pushed out over the uplands a few miles south of the river. in indiana, except at the extreme east, its margin fell considerably short of the ohio; in illinois it reached well toward that river, attaining here its most southerly latitude. west of the mississippi, the line which marks the limit of its advance curves to the northward, and follows, in a general way, the course of the missouri river. the total area of the north american ice sheet, at the time of its maximum development, has been estimated to have been about , , square miles, or about ten times the estimated area of the present ice-field of greenland. within the general area covered by the ice, there is an area of several thousand square miles, mainly in southwestern wisconsin, where there is no drift. the ice, for some reason, failed to cover this _driftless area_ though it overwhelmed the territory on all sides. [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xxxiii. the north american ice sheet, at the time of maximum development.] [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xxxiv. view from the north of the owl's head, a hill two miles north of east of merrimac, which has been shaped by the ice. the side to the left is the stone side.] plate ii shows the limit of ice advance in the area here described. the region may have been affected by the ice of more than one glacial epoch, but the chief results now observable were effected during the last, and the others need not be considered. _the work of glacier ice._ as the edge of an ice sheet, or as the end of a glacier, retreats, the land which it has previously covered is laid bare, and the effects which the passage of the ice produced may be seen. in some cases one may actually go back a short distance beneath the ice now in motion, and see its mode of work and the results it is effecting. the beds of living glaciers, and the beds which glaciers have recently abandoned, are found to present identical features. because of their greater accessibility, the latter offer the better facilities for determining the effects of glaciation. the conspicuous phenomena of abandoned glacier beds fall into two classes, ( ) those which pertain to the bed rock over which the ice moved, and ( ) those which pertain to the drift left by the ice. _erosive work of the ice._--_effect on topography._--the leading features of the rock bed over which glacier ice has moved, are easily recognized. its surface is generally smoothed and polished, and frequently marked by lines (striæ) or grooves, parallel to one another. an examination of the bottom of an active glacier discloses the method by which the polishing and scoring are accomplished. the lower surface of the ice is thickly set with a quantity of clay, sand, and stony material of various grades of coarseness. these earthy and stony materials in the base of the ice are the tools with which it works. thus armed, the glacier ice moves slowly forward, resting down upon the surfaces over which it passes with the whole weight of its mass, and the grinding action between the stony layer at the base of the ice and the rock bed over which it moves, is effective. if the material in the bottom of the ice be fine, like clay, the rock bed is polished. if coarser materials, harder than the bed-rock, be mingled with the fine, the rock bed of the glacier will be scratched as well as polished. if there are bowlders in the bottom of the ice they may cut grooves or gorges in the underlying rock. the grooves may subsequently be polished by the passage over and through them of ice carrying clay or other fine, earthy matter. all these phases of rock wear may be seen about the termini of receding glaciers, on territory which they have but recently abandoned. there can thus be no possible doubt as to the origin of the polishing, planing and scoring. there are other peculiarities, less easily defined, which characterize the surface of glacier beds. the wear effected is not confined to the mere marking of the surface over which it passes. if prominences of rock exist in its path, as is often the case, they oppose the movement of the ice, and receive a corresponding measure of abrasion from it. if they be sufficiently resistant they may force the ice to yield by passing over or around them; but if they be weak, they are likely to be destroyed. as the ice of the north american ice sheet advanced, seemingly more rigid when it encountered yielding bodies, and more yielding when it encountered resistant ones, it denuded the surface of its loose and movable materials, and carried them forward. this accumulation of earthy and stony debris in the bottom of the ice, gave it a rough and grinding lower surface, which enabled it to abrade the land over which it passed much more effectively than ice alone could have done. every hill and every mound which the ice encountered contested its advance. every sufficiently resistant elevation compelled the ice to pass around or over it; but even in these cases the ice left its marks upon the surface to which it yielded. the powerful pressure of pure ice, which is relatively soft, upon firm hills of rock, which are relatively hard, would effect little. the hills would wear the ice, but the effect of the ice on the hills would be slight. but where the ice is supplied with earthy and stony material derived from the rock itself, the case is different. under these conditions, the ice, yielding only under great pressure and as little as may be, rubs its rock-shod base over every opposing surface, and with greatest severity where it meets with greatest resistance. its action may be compared to that of a huge "flexible-rasp" fitting down snugly over hills and valleys alike, and working under enormous pressure. the abrasion effected by a moving body of ice under such conditions would be great. every inch of ice advance would be likely to be attended by loss to the surface of any obstacle over or around which it is compelled to move. the sharp summits of the hills, and all the angular rugosities of their surfaces would be filed off, and the hills smoothed down to such forms as will offer progressively less and less resistance. if the process of abrasion be continued long enough, the forms, even of the large hills, may be greatly altered, and their dimensions greatly reduced. among the results of ice wear, therefore, will be a lowering of the hills, and a smoothing and softening of their contours, while their surfaces will bear the marks of the tools which fashioned them, and will be polished, striated or grooved, according to the nature of the material which the ice pressed down upon them during its passage. figs. and show the topographic effects which ice is likely to produce by erosion. plate xxxiv is a hill two miles northeast of merrimac, which shows how perfectly the wear actually performed corresponds to that which might be inferred. [illustration: fig. .--a hill before the ice passes over it.] a rock hill was sometimes left without covering of drift after having been severely worn by the ice. such a hill is known as a _roche moutonnée_. an example of this type of hill occurs three miles north of east of baraboo at the point marked z on plate xxxvii. this hill, composed of quartzite, is less symmetrical than those shown in figs. and . its whole surface, not its stoss side only, has been smoothed and polished by the ice. this hill is the most accessible, the most easily designated, and, on the whole, the best example of a _roche moutonnée_ in the region, though many other hills show something of the same form. [illustration: fig. .--the same hill after it has been eroded by the ice. a the stoss side. b the lee side.] it was not the hills alone which the moving ice affected. where it encountered valleys in its course they likewise suffered modification. where the course of a valley was parallel to the direction of the ice movement, the ice moved through it. the depth of moving ice is one of the determinants of its velocity, and because of the greater depth of ice in valleys, its motion here was more rapid than on the uplands above, and its abrading action more powerful. under these conditions the valleys were deepened and widened. where the courses of the valleys were transverse to the direction of ice movement, the case was different. the ice was too viscous to span the valleys, and therefore filled them. in this case it is evident that the greater depth of the ice in the valley will not accelerate its motion, since the ice in the valley-trough and that above it are in a measure opposed. if left to itself, the ice in the valley would tend to flow in the direction of the axis of the valley. but in the case under consideration, the ice which lies above the valley depression is in motion at right angles to the axis of the valley. under these circumstances three cases might arise: ( ) if the movement of the ice sheet over the valley were able to push the valley ice up the farther slope, and out on the opposite highland, this work would retard the movement of the upper ice, since the resistance to movement would be great. in this case, the thickness of the ice is not directly and simply a determinant of its velocity. under these conditions the bottom of the valley would not suffer great erosion, since ice did not move along it; but that slope of the valley against which the ice movement was projected would suffer great wear (fig. ). the valley would therefore be widened, and the slope suffering greatest wear would be reduced to a lower angle. shallow valleys, and those possessing gentle slopes, favor this phase of ice movement and valley wear. [illustration: fig. .--diagram showing effect on valley of ice moving transversely across it.] ( ) the ice in the valley might become stationary, in which case it might serve as a bridge for the upper ice to cross on (fig. ). in this case also the total thickness of ice will not be a determinant of its velocity, for it is the thickness of the moving ice only, which influences the velocity. in this case the valley would not suffer much wear, so long as this condition of things continued. valleys which have great depth relative to the thickness of the ice, and valleys whose slopes are steep, favor this phase of movement. ( ) in valleys whose courses are transverse to the direction of ice movement, transverse currents of ice may exist, following the direction of the valleys. if the thickness of the ice be much greater than the depth of the valley, if the valley be capacious, and if one end of it be open and much lower than the other, the ice filling it may move along its axis, while the upper ice continues in its original course at right angles to the valley. in this case the valley would be deepened and widened, but this effect would be due to the movement along its course, rather than to that transverse to it. [illustration: fig. --diagram to illustrate case where ice fills a valley (c) and the upper ice then moves on over the filling.] if the course of a valley were oblique to the direction of ice movement, its effect on the movement of ice would be intermediate between that of valleys parallel to the direction of movement, and those at right angles to it. it follows from the foregoing that the corrasive effects of ice upon the surface over which it passed, were locally dependent on pre-existent topography, and its relation to the direction of ice movement. in general, the effort was to cut down prominences, thus tending to level the surface. but when it encountered valleys parallel to its movement they were deepened, thus locally increasing relief. whether the reduction of the hills exceeded the deepening of the valleys, or whether the reverse was true, so far as corrasion alone is concerned, is uncertain. but whatever the effect of the erosive effect of ice action upon the total amount of relief, the effect upon the contours was to make them more gentle. not only were the sharp hills rounded off, but even the valleys which were deepened were widened as well, and in the process their slopes became more gentle. a river-erosion topography, modified by the wearing (not the depositing) action of the ice, would be notably different from the original, by reason of its gentler slopes and softer contours (figs. and ). _deposition by the ice. effect on topography._--on melting, glacier ice leaves its bed covered with the debris which it gathered during its movement. had this debris been equally distributed on and in and beneath the ice during its movement, and had the conditions of deposition been everywhere the same, the drift would constitute a mantle of uniform thickness over the underlying rock. such a mantle of drift would not greatly alter the topography; it would simply raise the surface by an amount equal to the thickness of the drift, leaving elevations and depressions of the same magnitude as before, and sustaining the same relations to one another. but the drift carried by the ice, in whatever position, was not equally distributed during transportation, and the conditions under which it was deposited were not uniform, so that it produced more or less notable changes in the topography of the surface on which it was deposited. the unequal distribution of the drift is readily understood. the larger part of the drift transported by the ice was carried in its basal portion; but since the surface over which the ice passed was variable, it yielded a variable amount of debris to the ice. where it was hilly, the friction between it and the ice was greater than where it was plain, and the ice carried away more load. from areas where the surface was overspread by a great depth of loose material favorably disposed for removal, more debris was taken than from areas where material in a condition to be readily transported was meager. because of the topographic diversity and lithological heterogeneity of the surface of the country over which it passed, some portions of the ice carried much more drift than others, and when the ice finally melted, greater depths of drift were left in some places than in others. not all of the material transported by the ice was carried forward until the ice melted. some of it was probably carried but a short distance from its original position before it lodged. drift was thus accumulating at some points beneath the ice during its onward motion. at such points the surface was being built up; at other points, abrasion was taking place, and the surface was being cut down. the drift mantle of any region does not, therefore, represent simply the material which was on and in and beneath the ice of that place at the time of its melting, but it represents, in addition, all that lodged beneath the ice during its movement. the constant tendency was for the ice to carry a considerable part of its load forward toward its thinned edge, and there to leave it. it follows that if the edge of the ice remained constant in position for any considerable period of time, large quantities of drift would have accumulated under its marginal portion, giving rise to a belt of relatively thick drift. other things being equal, the longer the time during which the position of the edge was stationary, the greater the accumulation of drift. certain ridge-like belts where the drift is thicker than on either hand, are confidently believed to mark the position where the edge of the ice-sheet stood for considerable periods of time. because of the unequal amounts of material carried by different parts of the ice, and because of the unequal and inconstant conditions of deposition under the body of the ice and its edge, the mantle of drift has a very variable thickness; and a mantle of drift of variable thickness cannot fail to modify the topography of the region it covers. the extent of the modification will depend on the extent of the variation. this amounts in the aggregate, to hundreds of feet. the continental ice sheet, therefore, modified the topography of the region it covered, not only by the wear it effected, but also by the deposits it made. in some places it chanced that the greater thicknesses of drift were left in the positions formerly marked by valleys. locally the body of drift was so great that valleys were completely filled, and therefore completely obliterated as surface features. less frequently, drift not only filled the valleys but rose even higher over their former positions than on either side. in other places the greater depths of drift, instead of being deposited in the valleys, were left on pre-glacial elevations, building them up to still greater heights. in short, the mantle of drift of unequal thickness was laid down upon the rock surface in such a manner that the thicker parts sometimes rest on hills and ridges, sometimes on slopes, sometimes on plains, and sometimes in valleys. [illustration: fig. .--diagrammatic section showing relation of drift to underlying rock, where the drift is thick relative to the relief of the rock. a and b represent the location of post-glacial valleys.] these relations are suggested by figs. and . from them it will be seen that in regions where the thickness of the drift is great, relative to the relief of the underlying rock, the topography may be completely changed. not only may some of the valleys be obliterated by being filled, but some of the hills may be obliterated by having the lower land between them built up to their level. in regions where the thickness of the drift is slight, relative to the relief of the rock beneath, the hills cannot be buried, and the valleys cannot be completely filled, so that the relative positions of the principal topographic features will remain much the same after the deposition of the drift, as before (fig. ). [illustration: fig. .--diagrammatic section showing relation of drift to underlying rock where the drift is thin relative to the relief of the underlying rock.] in case the pre-glacial valleys were filled and the hills buried, the new valleys which the surface waters will in time cut in the drift surface will have but little correspondence in position with those which existed before the ice incursion. a new system of valleys, and therefore a new system of ridges and hills, will be developed, in some measure independent of the old. these relations are illustrated by fig. . inequalities in the thickness of drift lead to a still further modification of the surface. it frequently happened that in a plane or nearly plane region a slight thickness of drift was deposited at one point, while all about it much greater thicknesses were left. the area of thin drift would then constitute a depression, surrounded by a higher surface built up by the thicker deposits. such depressions would at first have no outlets, and are therefore unlike the depressions shaped by rain and river erosion. the presence of depressions without outlets is one of the marks of a drift-covered (glaciated) country. in these depressions water may collect, forming lakes or ponds, or in some cases only marshes and bogs. direction of ice movement. the direction in which glacier ice moved may be determined in various ways, even after the ice has disappeared. the shapes of the rock hills over which the ice passed, the direction from which the materials of the drift came, and the course of the margin of the drift, all show that the ice of south central wisconsin was moving in a general southwest direction. in the rock hills, this is shown by the greater wear of their northeast ("stoss") sides (plate xxxiv). from the course of the drift margin, the general direction of movement may be inferred when it is remembered that the tendency of glacier ice on a plane surface is to move at right angles to its margin. for the exact determination of the direction of ice movement, recourse must be had to the striæ on the bed-rock. were the striated rock surface perfectly plane, and were the striæ even lines, they would only tell that the ice was moving in one of two directions. but the rock surface is not usually perfectly plane, nor the striæ even lines, and between the two directions which lines alone might suggest, it is usually possible to decide. the minor prominences and depressions in the rock surface were shaped according to the same principles that govern the shaping of hills (fig. ) and valleys (fig. ); that is, the stoss sides of the minor prominences, and the distal sides of small depressions suffered the more wear. with a good compass, the direction of the striæ may be measured to within a fraction of a degree, and thus the direction of ice movement in a particular place be definitely determined. the striæ which have been determined about baraboo are shown on plate ii. _effect of topography on movement._--the effect of glaciation on topography has been sketched, but the topography in turn exerted an important influence on the direction of ice movement. the extreme degree of topographic influence is seen in mountain regions like the alps, where most of the glaciers are confined strictly to the valleys. as an ice sheet invades a region, it advances first and farthest along the lines of least resistance. in a rough country with great relief, tongues or lobes of ice would push forward in the valleys, while the hills or other prominences would tend to hold back or divide the onward moving mass. the edge of an ice sheet in such a region would be irregular. the marginal lobes of ice occupying the valleys would be separated by re-entrant angles marking the sites of hills and ridges. if the ice crossed a plane surface above which rose a notable ridge or hill, the first effect of the hill would be to indent the ice. the ice would move forward on either side, and if its thickness became sufficiently great, the parts moving forward on either side would again unite beyond it. a hill thus surrounded by ice is a nunatak. later, as the advancing mass of ice became thicker, it might completely cover the hill; but the thickness of ice passing over the hill would be less than that passing on either side by an amount equal to the height of the hill. it follows that as ice encounters an isolated elevation, three stages in its contest with the obstruction may be recognized: ( ) the stage when the ridge or hill acts as a wedge, dividing the moving ice into lobes, fig. ; ( ) the nunatak stage, when the ice has pushed forward and reunited beyond the hill, fig. ; ( ) the stage when the ice has become sufficiently deep to cover the hill. [illustration: fig. .--diagrammatic representation of the effect of a hill on the edge of the ice.] after the ice has disappeared, the influence of the obstruction might be found in the disposition of the drift. if recession began during the first stage, that is, when the ice edge was separated into lobes, the margin of the drift should be lobate, and would loop back around the ridge from its advanced position on either side. if recession began during the second stage, that is, when the lobes had become confluent and completely surrounded the hill, a _driftless area_ would appear in the midst of drift. if recession began during the third stage, that is, after the ice had moved on over the obstruction, the evidence of the sequence might be obliterated; but if the ice moved but a short distance beyond the hill, the thinner ice over the hill would have advanced less far than the thicker ice on either side (fig. ), and the margin of the drift would show a re-entrant pointing back toward the hill, though not reaching it. all these conditions are illustrated in the devil's lake region. [illustration: fig. .--same as fig. , when the ice has advanced farther.] _limit of the ice._ the region under description is partly covered with drift, and partly free from it. the limit of the ice, at the time of its maximum expansion is well defined at many points, and the nature and position of the drift limit are so unique as to merit attention (see plates ii and xxxvii). they illustrate many of the principles already discussed. the ice which covered the region was the western margin of the green bay lobe (fig. ) of the last continental ice sheet. its limit in this region is marked by a ridge-like accumulation of drift, the _terminal moraine_, which here has a general north-south direction. the region may have been affected by the ice of more than one epoch, but since the ice of the last epoch advanced as far to the west in this region as that of any earlier epoch, the moraine is on the border between the glaciated country to the east, and the driftless area to the west (plates i and ii). that part of the moraine which lies west of the wisconsin river follows a somewhat sinuous course from kilbourn city to a point a short distance north of prairie du sac. the departures from this general course are especially significant of the behavior of glacier ice. [illustration: fig. .--map showing relations of lobes of ice during the wisconsin ice epoch, to the driftless area.] in the great depression between the quartzite ranges, the moraine bends westward, showing that the ice advanced farther on the lowlands than on the ridges. as the moraine of this low area approaches the south range, it curves to the east. at the point southwest of baraboo where the easterly curve begins to show itself, the moraine lies at the north base of the quartzite range; but as it is traced eastward, it is found to lie higher and higher on the slope of the range, until it reaches the crest nearly seven miles from the point where the eastward course was assumed. at this point it crosses the range, and, once across the crest, it turns promptly to the westward on the lower land to the south. here the ice advanced up the valley between the east bluff (east of the lake) and the devil's nose (plate xxxvii), again illustrating the fact that lowlands favor ice advance. the valley between the devil's nose and the east bluff is a narrow one, and the ice advanced through it nearly to the present site of the lake. meanwhile the restraining influence of the "nose" was making itself felt, and the margin of the ice curved back from the bottom of the bluff near kirkland, to the top of the bluff at the end of the nose. here the edge of the ice crossed the point of the nose, and after rounding it, turned abruptly to the west. thence its edge lay along the south slope of the ridge, descending from the crest of the ridge at the nose, to the base of the ridge two miles farther west. here the ice reached its limit on the lowland, and its edge, as marked by the moraine, turned southward, reaching the wisconsin river about a mile and a half above prairie du sac. the course of the terminal moraine across the ridges is such as the margin of the ice would normally have when it advanced into a region of great relief. the great loop in the moraine with its eastern extremity at k, plate xxxvii, is explained by the presence of the quartzite ridge which retarded the advancing ice while it moved forward on either side. the minor loop around the devil's nose is explained in the same way. both the main loop, and the smaller one on the nose, illustrate the point made earlier in the text. the narrow and curious loop at m, is of a slightly different origin, though in principle the same. it is in the lee of a high point in the quartzite ridge. the ice surmounted this point, and descended its western slope; but the thickness of the ice passing over the summit was so slight that it advanced but a short distance down the slope before its force was exhausted, while the thicker ice on either side advanced farther before it was melted. _glacial deposits._ before especial reference is made to the drift of this particular region, it will be well to consider the character of drift deposits in general. when the ice of the continental glacier began its motion, it carried none of the stony and earthy debris which constitute the drift. these materials were derived from the surface over which the ice moved. from the method by which it was gathered, it is evident that the drift of any locality may contain fragments of rock of every variety which occurs along the route followed by the ice which reached that locality. where the ice had moved far, and where there were frequent changes in the character of the rock constituting its bed, the variety of materials in the drift is great. the heterogeneity of the drift arising from the diverse nature of the rocks which contributed to it is _lithological heterogeneity_--a term which implies the commingling of materials derived from different rock formations. thus it is common to find pieces of sandstone, limestone, quartzite, granite, gneiss, schist, etc., intimately commingled in the drift, wherever the ice which produced it passed over formations of these several sorts of rock. lithological heterogeneity is one of the notable characteristics of glacial formations. another characteristic of the drift is its _physical heterogeneity_. as first gathered from the bed of moving ice, some of the materials of the drift were fine and some coarse. the tendency of the ice in all cases was to reduce its load to a still finer condition. some of the softer materials, such as soft shale, were crushed or ground to powder, forming what is known in common parlance as clay. clayey (fine) material is likewise produced by the grinding action of ice-carried bowlders upon the rock-bed, and upon one another. other sorts of rock, such as soft sandstone, were reduced to the physical condition of sand, instead of clay, and from sand to bowlders all grades of coarseness and fineness are represented in the glacial drift. [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xxxv. cut in drift, showing its physical heterogeneity.] since the ice does not assort the material which it carries, as water does, the clay, sand, gravel and bowlders will not, by the action of the ice, be separated from one another. they are therefore not stratified. as left by the ice, these physically heterogeneous materials are confusedly commingled. the finer parts constitute a matrix in which the coarser are embedded. physical heterogeneity (plate xxxv), therefore, is another characteristic of glacial drift. it is not to be understood that the proportions of these various physical elements, clay, sand, gravel, and bowlders, are constant. locally any one of them may predominate over any or all the others to any extent. since lithological and physical heterogeneity are characteristics of glacial drift, they together afford a criterion which is often of service in distinguishing glacial drift from other surface formations. it follows that this double heterogeneity constitutes a feature which can be utilized in determining the former extension of existing glaciers, as well as the former existence of glaciers where glaciers do not now exist. another characteristic of glacial drift, and one which clearly distinguishes it from all other formations with which it might be confounded, is easily understood from its method of formation. if the ice in its motion holds down rock debris upon the rock surface over which it passes with such pressure as to polish and striate the bed-rock, the material carried will itself suffer wear comparable to that which it inflicts. thus the stones, large and small, of glacial drift, will be smoothed and striated. this sort of wear on the transported blocks of rock, is effected both by the bed-rock reacting on the bowlders transported over it, and by bowlders acting on one another in and under the ice. the wear of bowlders by bowlders is effected wherever adjacent ones are carried along at different rates. since the rate of motion of the ice is different in different parts of the glacier, the mutual abrasion of transported materials is a process constantly in operation. a large proportion of the transported stone and blocks of rock may thus eventually become striated. from the nature of the wear to which the stones are subjected when carried in the base of the ice, it is easy to understand that their shapes must be different from those of water-worn materials. the latter are rolled over and over, and thus lose all their angles and assume a more or less rounded form. the former, held more or less firmly in the ice, and pressed against the underlying rock or rock debris as they are carried slowly forward, have their faces planed and striated. the planation and striation of a stone need not be confined to its under surface. on either side or above it other stones, moving at different rates, are made to abrade it, so that its top and sides may be planed and scored. if the ice-carried stones shift their positions, as they may under various circumstances, new faces will be worn. the new face thus planed off may meet those developed at an earlier time at sharp angles, altogether unlike anything which water-wear is capable of producing. the stone thus acted upon shows a surface bounded by planes and more or less beveled, instead of a rounded surface such as water wear produces. we find, then, in the shape of the bowlders and smaller stones of the drift, and in the markings upon their surfaces, additional criteria for the identification of glacier drift (plate xxxvi). the characteristics of glacial drift, so far as concerns its constitution, may then be enumerated as, ( ) its lithological, and ( ) physical heterogeneity; ( ) the shapes, and ( ) the markings of the stones of the drift. in structure, the drift which is strictly glacial, is unstratified. in the broadest sense of the term, all deposits made by glacier ice are _moraines_. those made beneath the ice and back from its edge constitute the _ground moraine_, and are distinguished from the considerable marginal accumulations which, under certain conditions, are accumulated at or near the margin. these marginal accumulations are _terminal moraines_. associated with the moraines which are the deposits of the ice directly, there are considerable bodies of stratified gravel and sand, the structure of which shows that they were laid down by water. this is to be especially noted, since lack of stratification is popularly supposed to be the especial mark of the formations to which the ice gave rise. [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xxxvi. glaciated stones, showing both form and striæ. (matz.)] these deposits of stratified drift lie partly beyond the terminal moraine, and partly within it. they often sustain very complicated relations both to the ground and terminal moraines. the drift as a whole is therefore partly stratified and partly unstratified. structurally the two types are thoroughly distinct, but their relations are often most complex, both horizontally and vertically. a fuller consideration of these relations will be found on a later page. _the ground moraine._ the ground moraine constitutes the great body of the glacial drift. _bowlder clay_, a term descriptive of its constitution in some places, and _till_, are other terms often applied to the ground moraine. the ground moraine consists of all the drift which lodged beneath the ice during its advance, all that was deposited back from its edge while its margin was farthest south, and most of that which was deposited while the ice was retreating. from this mode of origin it is readily seen that the ground moraine should be essentially as widespread as the ice itself. locally, however, it failed of deposition. since it constitutes the larger part of the drift, the characteristics already enumerated as belonging to drift in general are the characteristics of the till. wherever obstacles to the progress of the ice lay in its path, there was a chance that these obstacles, rising somewhat into the lower part of the ice, would constitute barriers against which debris in the lower part of the ice would lodge. it might happen also that the ice, under a given set of conditions favoring erosion, would gather a greater load of rock-debris than could be transported under the changed conditions into which its advance brought it. in this case, some part of the load would be dropped and over-ridden. especially near the margin of the ice where its thickness was slight and diminishing, the ice must have found itself unable to carry forward the loads of debris which it had gathered farther back where its action was more vigorous. it will be readily seen that if not earlier deposited, all material gathered by the under surface of the ice would ultimately find itself at the edge of the glacier, for given time enough, ablation will waste all that part of the ice occupying the space between the original position of the debris, and the margin of the ice. under the thinned margin of the ice, therefore, considerable accumulations of drift must have been taking place while the ice was advancing. while the edge of the ice sheet was advancing into territory before uninvaded, the material accumulated beneath its edge at one time, found itself much farther from the margin at another and later time. under the more forcible ice action back from the margin, the earlier accumulations, made under the thin edge, were partially or wholly removed by the thicker ice of a later time, and carried down to or toward the new and more advanced margin. here they were deposited, to be in turn disturbed and transported still farther by the farther advance of the ice. since in its final retreat the margin of the ice must have stood at all points once covered by it, these submarginal accumulations of drift must have been made over the whole country once covered by the ice. the deposits of drift made beneath the marginal part of the ice during its retreat, would either cover the deposits made under the body of the ice at an earlier time, or be left alongside them. the constitution of the two phases of till, that deposited during the advance of the ice, and that deposited during its retreat, is essentially the same, and there is nothing in their relative positions to sharply differentiate them. they are classed together as _subglacial till_. subglacial till was under the pressure of the overlying ice. in keeping with these conditions of accumulation, the till often possesses a firmness suggestive of great compression. where its constitution is clayey it is often remarkably tough. where this is the case, the quality here referred to has given rise to the suggestive name "hard pan." where the constitution of the till is sandy, rather than clayey, this firmness and toughness are less developed, or may be altogether wanting, since sand cannot be compressed into coherent masses like clay. _constitution._--the till is composed of the more or less comminuted materials derived from the land across which the ice passed. the soil and all the loose materials which covered the rock entered into its composition. where the ice was thick and its action vigorous, it not only carried away the loose material which it found in its path, but, armed with this material, it abraded the underlying rock, wearing down its surface and detaching large and small blocks of rock from it. it follows that the constitution of the till at any point is dependent upon the nature of the soil and rock from which it was derived. if sandstone be the formation which has contributed most largely to the till, the matrix of the till will be sandy. where limestone instead of sandstone made the leading contribution to it, the till has a more earthy or clayey matrix. any sort of rock which may be very generally reduced to a fine state of division under the mechanical action of the ice, will give rise to clayey till. the nature and the number of the bowlders in the till, no less than the finer parts, depend on the character of the rock overridden. a hard and resistant rock, such as quartzite, will give rise to more bowlders in proportion to the total amount of material furnished to the ice, than will softer rock. shale or soft sandstone, possessing relatively slight resistance, will be much more completely crushed. they will, therefore, yield proportionately fewer bowlders than harder formations, and more of the finer constituents of till. the bowlders taken up by the ice as it advanced over one sort of rock and another, possessed different degrees of resistance. the softer ones were worn to smaller dimensions or crushed with relative ease and speed. bowlders of soft rock are, therefore, not commonly found in any abundance at great distances from their sources. the harder ones yielded less readily to abrasion, and were carried much farther before being destroyed, though even such must have suffered constant reduction in size during their subglacial journey. in general it is true that bowlders in the till, near their parent formations, are larger and less worn than those which have been transported great distances. the ice which covered this region had come a great distance and had passed over rock formations of many kinds. the till therefore contains elements derived from various formations; that is, it is lithologically heterogeneous. this heterogeneity cannot fail to attract the attention of one examining any of the many exposures of drift about baraboo at road gradings, or in the cuts along the railway. among the stones in the drift at these exposures are limestone, sandstone, quartzite, diabase, gabbro, gneiss, granite, schist, and porphyry, together with pieces of flint and chert. such an array may be found at any of the exposures within the immediate vicinity of devil's lake. to the north, and a few miles to the south of the baraboo ranges, the quartzite from these bluffs, and the porphyry from the point marked h in plate ii, are wanting, though other varieties of porphyry are present. the ice moved in a general west-southwest direction in this region, and the quartzite in the drift, so far as derived from the local formation, is therefore restricted to a narrow belt. the physical heterogeneity may be seen at all exposures, and is illustrated in plate xxxv. the larger stones of the drift are usually of some hard variety of rock. near the baraboo ranges, the local quartzite often predominates among the bowlders, and since such bowlders have not been carried far, they are often little worn. away from the ranges, the bowlders are generally of some crystalline rock, such as granite and diabase. bowlders of these sorts of rock are from a much more distant source, and are usually well worn. in general the till of any locality is made up largely of material derived from the formations close at hand. this fact seems to afford sufficient warrant for the conclusion that a considerable amount of deposition must have gone on beneath the ice during its movement, even back from its margin. to take a concrete illustration, it would seem that the drift of southeastern wisconsin should have had a larger contribution than it has of material derived from canadian territory, if material once taken up by the ice was all or chiefly carried down to its thinned edge before deposition. the fact that so little of the drift came from these distant sources would seem to prove that a large part of the material moved by the ice, is moved a relatively short distance only. the ice must be conceived of as continually depositing parts of its load, and parts which it has carried but a short distance, as it takes up new material from the territory newly invaded. in keeping with the character of till in general, that about devil's lake was derived largely from the sandstone, limestone and quartzite of the immediate vicinity, while a much smaller part of it came from more distant sources. this is especially noticeable in the fine material, which is made up mostly of the comminuted products of the local rock. _topography._--the topography of the ground moraine is in general the topography already described in considering the modification of preglacial topography effected by ice deposition. as left by the ice, its surface was undulating. the undulations did not take the form of hills and ridges with intervening valleys, but of swells and depressions standing in no orderly relationship to one another. undrained depressions are found in the ground moraine, but they are, as a rule, broader and shallower than the "kettles" common to terminal moraines. it is in the broad, shallow depressions of the ground moraine that many of the lakes and more of the marshes of southeastern wisconsin are located. the rolling, undulating topography characteristic of ground moraines is well shown about the city of baraboo and between that point and the lake, and at many less easily designated points about merrimac. in thickness the ground moraine reaches at least feet, though its average is much less--too little to obliterate the greater topographic features of the rock beneath. it is, however, responsible for many of the details of the surface. _terminal moraines._ the marginal portion of the ice sheet was more heavily loaded--certainly more heavily loaded relative to its thickness--than any other. toward its margin the thinned ice was constantly losing its transportive power, and at its edge this power was altogether gone. since the ice was continually bringing drift down to this position and leaving it there, the rate of drift accumulation must have been greater, on the average, beneath the edge of the ice than elsewhere. whenever, at any stage in its history, the edge of the ice remained essentially constant in position for a long period of time, the corresponding submarginal accumulation of drift was great, and when the ice melted, the former site of the stationary edge would be marked by a broad ridge or belt of drift, thicker than that on either side. such thickened belts of drift are _terminal moraines_. it will be seen that a terminal moraine does not necessarily mark the terminus of the ice at the time of its greatest advance, but rather its terminus at any time when its edge was stationary or nearly so. from the conditions of their development it will be seen that these submarginal moraines may be made up of materials identical with those which constitute the ground moraine, and such is often the case. but water arising from the melting of the ice, played a much more important role at its margin than farther back beneath it. one result of its greater activity may be seen in the greater coarseness which generally characterizes the material of the terminal moraine as compared with that of the adjacent ground moraine. this is partly because the water carried away such of the finer constituents as it was able to transport, leaving the coarser behind. further evidence of the great activity of water near the margin of the ice is to be seen in the relatively large amount of assorted and stratified sand and gravel associated with the terminal moraine. such materials as were carried on the ice were dropped at its edge when the ice which bore them melted from beneath. if the surface of the ice carried many bowlders, many would be dropped along the line of its edge wherever it remained stationary for any considerable period of time. a terminal moraine therefore embraces ( ) the thick belt of drift accumulated beneath the edge of the ice while it was stationary, or nearly so; and ( ) such debris as was carried on the surface of the ice and dumped at its margin. in general the latter is relatively unimportant. at various stages in its final retreat, the ice made more or less protracted halts. these halting places are marked by marginal moraines of greater or less size, depending on the duration of the stop, and the amount of load carried. a terminal moraine is not the sharp and continuous ridge we are wont to think it. it is a belt of thick drift, rather than a ridge, though it is often somewhat ridge-like. in width, it varies from a fraction of a mile to several miles. in the region under consideration it is rarely more than fifty feet high, and rarely less than a half mile wide, and a ridge of this height and width is not a conspicuous topographic feature in a region where the relief is so great as that of the devil's lake region. _topography of terminal moraines._--the most distinctive feature of a terminal moraine is not its ridge-like character, but its peculiar topography. in general, it is marked by depressions without outlets, associated with hillocks and short ridges comparable in dimensions to the depressions. both elevations and depressions are, as a rule, more abrupt than in the ground moraine. in the depressions there are many marshes, bogs, ponds and small lakes. the shapes and the abundance of round and roundish hills have locally given rise to such names as "the knobs," "short hills," etc. elsewhere the moraine has been named the "kettle range" from the number of kettle-like depressions in its surface. it is to be kept in mind that it is the association of the "knobs" and "kettles," rather than either feature alone, which is the distinctive mark of terminal moraine topography. [illustration: fig. .--sketch of terminal moraine topography, on the quartzite ridge east of devil's lake. (matz.)] the manner in which the topography of terminal moraines was developed is worthy of note. in the first place, the various parts of the ice margin carried unequal amounts of debris. this alone would have caused the moraine of any region to have been of unequal height and width at different points. in the second place, the margin of the ice, while maintaining the same _general_ position during the making of a moraine, was yet subject to many minor oscillations. it doubtless receded to some slight extent because of increased melting during the summer, to advance again during the winter. in its recession, the ice margin probably did not remain exactly parallel to its former position. if some parts receded more than others, the details of the line of its margin may have been much changed during a temporary retreat. when the ice again advanced, its margin may have again changed its form in some slight measure, so as to be parallel neither with its former advanced position, nor with its position after its temporary retreat. with each successive oscillation of the edge, the details of the margin may have altered, and at each stage the marginal deposits corresponded with the edge. there might even be considerable changes in the edge of the ice without any general recession or advance, as existing glaciers show. it was probably true of the margin of the american ice sheet, as of existing glaciers, that there were periods of years when the edge of the ice receded, followed by like periods when it remained stationary or nearly so, and these in turn followed by periods of advance. during any advance, the deposits made during the period of recession would be overridden and disturbed or destroyed. if the ice were to retreat and advance repeatedly during a considerable period of time, always within narrow limits, and if during this oscillation the details of its margin were frequently changing, the result would be a complex or "tangle" of minor morainic ridges of variable heights and widths. between and among the minor ridges there would be depressions of various sizes and shapes. thus, it is conceived, many of the peculiar hillocks and hollows which characterize terminal moraines may have arisen. some of the depressions probably arose in another way. when the edge of the ice retreated, considerable detached masses of ice might be left beyond the main body. this might be buried by gravel and sand washed out from the moraine. on melting, the former sites of such blocks of ice would be marked by "kettles." in the marginal accumulations of drift as first deposited, considerable quantities of ice were doubtless left. when this melted, the drift settled and the unequal settling may have given rise to some of the topographic irregularities of the drift. _the terminal moraine about devil's lake._--on the lower lands, the terminal moraine of the devil's lake region has the features characteristic of terminal moraines in general. it is a belt of thick drift varying in width from half a mile or less to three-quarters of a mile or more. its surface is marked by numerous hills and short ridges, with intervening depressions or "kettles." some of the depressions among the hills contain water, making ponds or marshes, though the rather loose texture of the drift of this region is not favorable to the retention of water. the moraine belt, as a whole, is higher than the land on either side. it is therefore somewhat ridge-like, and the small, short hills and ridges which mark its surface, are but constituent parts of the larger, broader ridge. approached from the west, that is from the driftless side, the moraine on the lower lands is a somewhat prominent topographic feature, often appearing as a ridge thirty, forty or even fifty feet in height. approached from the opposite direction, that is, from the ground moraine, it is notably less prominent, and its inner limit wherever located, is more or less arbitrary. [illustration: fig. .--cut through the terminal moraine just east of kirkland, partially diagrammatic.] a deep, fresh railway cut in the moraine southeast of devil's lake illustrates its complexity of structure, a complexity which is probably no greater than that at many other points where exposures are not seen. the section is represented in fig. . the stratified sand to the right retains even the ripple-marks which were developed when it was deposited. to the left, at the same level, there is a body of _till_ (unstratified drift), over which is a bed of stoneless and apparently structureless clay. in a depression just above the clay with till both to the right and left, is a body of loam which possesses the characteristics of normal loess. it also contains calcareous concretions, though no shells have been found. this occurrence of loess is the more noteworthy, since loess is rarely found in association with drift of the last glacial epoch.[ ] [ ] an account of loess in connection with the drift of the last glacial epoch is given in the _journal of geology_, vol. iv, pp. - . for a general account of loess, see sixth annual report of u.s. geological survey. _the moraine on the main quartzite range._--in tracing the moraine over the greater quartzite range, it is found to possess a unique feature in the form of a narrow but sharply defined ridge of drift, formed at the extreme margin of the ice at the time of its maximum advance. for fully eleven miles, with but one decided break, and two short stretches where its development is not strong, this unique marginal ridge separates the drift-covered country on the one hand, from the driftless area on the other. in its course the ridge lies now on slopes, and now on summits, but in both situations preserves its identity. where it rests on a plain, or nearly plain surface, its width at base varies from six to fifteen rods, and its average height is from twenty to thirty feet. its crest is narrow, often no more than a single rod. where it lies on a slope, it is asymmetrical in cross section (see fig. ), the shorter slope having a vertical range of ten to thirty-five feet, and its longer a range of forty to one hundred feet. this asymmetrical form persists throughout all that portion of the ridge which lies on an inclined surface, the slope of which does not correspond with the direction of the moraine. where it lies on a flat surface, or an inclined surface the slope of which corresponds in direction with the course of the ridge itself, its cross section is more nearly symmetrical (see fig. ). in all essential characteristics this marginal ridge corresponds with the _end-moräne_ of the germans. [illustration: fig. .--diagrammatic cross-section of the marginal ridge as it occurs on the south slope of the devil's nose. the slope below, though glaciated, is nearly free from drift.] [illustration: fig. .--diagrammatic cross-section of the marginal ridge as it appears when its base is not a sloping surface.] for the sake of bringing out some of its especially significant features, the ridge may be traced in detail, commencing on the south side of the west range. where the moraine leaves the lowlands south of the devil's nose, and begins the ascent of the prominence, the marginal ridge first appears at about the -foot contour (f, plate xxxvii). though at first its development is not strong, few rods have been passed before its crest is fifteen to twenty feet above the driftless area immediately to the north (see fig. ) and from forty to one hundred feet above its base to the south, down the slope. in general the ridge becomes more distinct with increasing elevation, and except for two or three narrow post-glacial erosion breaks, is continuous to the very summit at the end of the nose (g). the ridge in fact constitutes the uppermost forty or forty-five feet of the crest of the nose, which is the highest point of the west range within the area shown on the map. throughout the whole of this course the marginal ridge lies on the south slope of the nose, and has the asymmetrical cross section shown in fig. . above (north of) the ridge at most points not a bowlder of drift occurs. so sharply is its outer (north) margin defined, that at many points it is possible to locate it within the space of less than a yard. at the crest of the nose (g) the marginal ridge, without a break, swings northward, and in less than a quarter of a mile turns again to the west. bearing to the north it presently reaches (at h) the edge of the precipitous bluff, bordering the great valley at the south end of the lake. between the two arms of the loop thus formed, the surface of the nose is so nearly level that it could have offered no notable opposition to the progress of the ice, and yet it failed to be covered by it. [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xxxvii. topographic map (contour interval feet) of a small area about devil's lake, taken from the baraboo sheet of the united states geological survey. each contour line connects points of the same elevation, and the figures upon them give the heights above sea level. where contour lines lie close together, they indicate steep slopes.] in the great valley between the nose and the east bluff, the marginal ridge does not appear. in the bottom of the valley the moraine takes on its normal form, and the slopes of the quartzite ridges on either hand are much too steep to allow any body of drift, or loose material of any sort, to lodge on them. ascending the east bluff a little east of the point where the drift ridge drops off the west bluff, the ridge is again found (at i) in characteristic development. for some distance it is located at the edge of the precipitous south face of the bluff. farther on it bears to the north, and soon crosses a col (j) in the ridge, building it up many feet above the level of the bed-rock. from this point eastward for about three miles the marginal ridge is clearly defined, the slopes about equal on either side, and the crest as nearly even as the topography of the underlying surface permits. the topographic relations in this part of the course are shown in fig. . at k, this marginal ridge attains its maximum elevation, , feet. at this great elevation, the ridge turns sharply to the northwest at an angle of more than °. following this direction for little more than half a mile, it turns to the west. at some points in this vicinity the ridge assumes the normal morainic habit, but this is true for short distances only. farther west, at l, it turns abruptly to the northeast and is sharply defined. it here loops about a narrow area less than sixty rods wide, and over half a mile in length, the sharpest loop in its whole course. the driftless tract enclosed by the arms of this loop is lower than the drift ridge on either hand. the ice on either side would need to have advanced no more than thirty rods to have covered the whole of it. from the minor loop just mentioned, the marginal ridge is continued westward, being well developed for about a mile and a half. at this point the moraine swings south to the north end of devil's lake, loses the unique marginal ridge which has characterized its outer edge across the quartzite range for so many miles, and assumes the topography normal to terminal moraines. at no other point in the united states, so far as known to the writers, is there so sharply marked a marginal ridge associated with the terminal moraine, for so long a distance. from plate ii it will be seen that the moraine as a whole makes a great loop to the eastward in crossing the quartzite range. from the detailed description just given of the course of the marginal ridge, it will be seen that it has three distinct loops; one on the devil's nose (west of g, plate xxxvii); one on the main ridge (west of k) and a minor one on the north side of the last (southwest of m). the first and third are but minor irregularities on the sides of the great loop, the head of which is at k. the significant fact in connection with these irregularities in the margin of the moraine is that each loop stands in a definite relation to a prominence. the meaning of this relation is at once patent. the great quartzite range was a barrier to the advance of the ice. acting as a wedge, it caused a re-entrant in the advancing margin of the glacier. the extent and position of the re-entrant is shown by the course of the moraine in plate ii. thus the great loop in the moraine, the head of which is at k, plate xxxvii, was caused by the quartzite range itself. the minor loops on the sides of the major are to be explained on the same principle. northeast of the minor loop on the north side of the larger one (m) there are two considerable hills, reaching an elevation of nearly , feet. though the ice advancing from the east-northeast overrode them, they must have acted like a wedge, to divide it into lobes. the ice which reached their summits had spent its energy in so doing, and was unable to move forward down the slope ahead, and the thicker bodies of ice which passed on either side of them, failed to unite in their lee (compare figs. and ). the application of the same principle to the loop on the devil's nose is evident. _constitution of the marginal ridge._--the material in the marginal ridge, as seen where erosion has exposed it, is till, abnormal, if at all, only in the large percentage of widely transported bowlders which it contains. this is especially true of the surface, where in some places per cent. of the large bowlders are of very distant origin, and that in spite of the fact that the ice which deposited them had just risen up over a steep slope of quartzite, which could easily have yielded abundant bowlders. in other places the proportion of foreign bowlders is small, no more than one in ten. in general, however, bowlders of distant origin predominate over those derived close at hand. _the slope of the upper surface of the ice at the margin._--the marginal ridge on the south slope of devil's nose leads to an inference of especial interest. its course lies along the south slope of the nose, from its summit on the east to its base on the west. throughout this course the ridge marks with exactness the position of the edge of the ice at the time of its maximum advance, and its crest must therefore represent the slope of the upper surface of the ice at its margin. the western end of the ridge (f, plate xxxvii) has an altitude of feet, and its eastern end (g) is just above the , -foot contour. the distance from the one point to the other is one and three-fourths miles, and the difference in elevation, feet. these figures show that the slope of the ice along the south face of this bluff was about feet per mile. this, so far as known, is the first determination of the slope of the edge of the continental ice sheet _at its extreme margin_. it is to be especially noted that these figures are for the extreme edge of the ice only. the angle of slope back from the edge was doubtless much less. _stratified drift._ while it is true that glacier ice does not distinctly stratify the deposits which it makes, it is still true that a very large part of the drift for which the ice of the glacial period was directly or indirectly responsible is stratified. that this should be so is not strange when it is remembered that most of the ice was ultimately converted into running water, just as the glaciers of today are. the relatively small portion which disappeared by evaporation was probably more than counterbalanced, at least near the margin of the ice, by the rain which fell upon it. it cannot be considered an exaggeration, therefore, to say that the total amount of water which operated on the drift, first and last, was hardly less than the total amount of the ice itself. the drift deposited by the marginal part of the ice was affected during its deposition, not only by the water which arose from the melting of the ice which did the depositing, but by much water which arose from the melting of the ice far back from the margin. the general mobility of the water, as contrasted with ice, allowed it to concentrate its activities along those lines which favored its motion, so that different portions of the drift were not affected equally by the water of the melting ice. all in all it will be seen that the water must have been a very important factor in the deposition of the drift, especially near the margin of the ice. but the ice sheet had a marginal belt throughout its whole history, and water must have been active and effective along this belt, not only during the decadence of the ice sheet, but during its growth as well. it is further to be noted that any region of drift stood good chance of being operated upon by the water after the ice had departed from it, so that in regions over which topography directed drainage after the withdrawal of the ice, the water had the last chance at the drift, and modified it in such a way and to such an extent as circumstances permitted. _its origin._--there are various ways in which stratified drift may arise in connection with glacier deposits. it may come into existence by the operation of water alone; or by the co-operation of ice and water. where water alone was immediately responsible for the deposition of stratified drift, the water concerned may have owed its origin to the melting ice, or it may have existed independently of the ice in the form of lakes. when the source of the water was the melting ice, the water may have been running, when it was actively concerned in the deposition of stratified drift; or it may have been standing (glacial lakes and ponds), when it was passively concerned. when ice co-operated with water in the development of stratified drift the ice was generally a passive partner. _glacial drainage._--the body of an ice sheet during any glacial period is probably melting more or less at some horizons all the time, and at all horizons some of the time. most of the water which is produced at the surface during the summer sinks beneath it. some of it may congeal before it sinks far, but much of it reaches the bottom of the ice without refreezing. it is probable that melting is much more nearly continuous in the body of a moving ice sheet than at its surface, and that some of the water thus produced sinks to the bottom of the ice without refreezing. at the base of the ice, so long as it is in movement, there is doubtless more or less melting, due both to friction and to the heat received by conduction from the earth below. thus in the ice and under the ice there must have been more or less water in motion throughout essentially all the history of an ice sheet. if it be safe to base conclusions on the phenomena of existing glaciers, it may be assumed that the waters beneath the ice, and to a less extent the waters in the ice, organized themselves to a greater or less degree into streams. for longer or shorter distances these streams flowed in the ice or beneath it. ultimately they escaped from its edge. the subglacial streams doubtless flowed, in part, in the valleys which affected the land surface beneath the ice, but they were probably not all in such positions. the courses of well-defined subglacial streams were tunnels. the bases of the tunnels were of rock or drift, while the sides and tops were of ice. it will be seen, therefore, that their courses need not have corresponded with the courses of the valleys beneath the ice. they may sometimes have followed lines more or less independent of topography, much as water may be forced over elevations in closed tubes. it is not to be inferred, however, that the subglacial streams were altogether independent of the sub-ice topography. the tunnels in which the water ran probably had too many leaks to allow the water to be forced up over great elevations. this, at least, must have been the case where the ice was thin or affected by crevasses. under such circumstances the topography of the land surface must have been the controlling element in determining the course of the subglacial drainage. when the streams issued from beneath the ice the conditions of flow were more or less radically changed, and from their point of issue they followed the usual laws governing river flow. if the streams entered static water as they issued from the ice, and this was true where the ice edge reached the sea or a lake, the static water modified the results which the flowing waters would otherwise have produced. _stages in the history of an ice sheet._--the history of an ice sheet which no longer exists involves at least two distinct stages. these are ( ) the period of growth, and ( ) the period of decadence. if the latter does not begin as soon as the former is complete, an intervening stage, representing the period of maximum ice extension, must be recognized. in the case of the ice sheets of the glacial period, each of these stages was probably more or less complex. the general period of growth of each ice sheet is believed to have been marked by temporary, but by more or less extensive intervals of decadence, while during the general period of decadence, it is probable that the ice was subject to temporary, but to more or less extensive intervals of recrudescence. for the sake of simplicity, the effects of these oscillations of the edge of the ice will be neglected at the outset, and the work of the water accompanying the two or three principal stages of an ice sheet's history will be outlined as if interruptions in the advance and in the retreat, respectively, had not occurred. as they now exist, the deposits of stratified drift made at the edge of the ice or beyond it during the period of its maximum extension present the simplest, and at the same time most sharply defined phenomena, and are therefore considered first. _deposits made by extraglacial waters during the maximum extension of the ice._ the deposits made by the water at the time of the maximum extension of the ice and during its final retreat, were never disturbed by subsequent glacier action. so far as not destroyed by subsequent erosion, they still retain the form and structure which they had at the outset. such drift deposits, because they lie at the surface, and because they are more or less distinct topographically as well as structurally, are better known than the stratified drift of other stages of an ice sheet's history. of stratified drift made during the maximum extension of the ice, and during its final retreat, there are several types. _a. at the edge of ice, on land._--if the subglacial streams flowed under "head," the pressure was relieved when they escaped from the ice. with this relief, there was diminution of velocity. with the diminution of velocity, deposition of load would be likely to take place. since these changes would be likely to occur at the immediate edge of the ice, one class of stratified drift deposits would be made in this position, in immediate contact with the edge of the ice, and their form would be influenced by it. at the stationary margin of an ice sheet, therefore, at the time of its maximum advance, ice and water must have co-operated to bring into existence considerable quantities of stratified drift. the edge of the ice was probably ragged, as the ends of glaciers are today, and as the waters issued from beneath it, they must frequently have left considerable quantities of such debris as they were carrying, against its irregular margin, and in its re-entrant angles and marginal crevasses. when the ice against which this debris was first lodged melted, the marginal accumulations of gravel and sand often assumed the form of kames. a typical kame is a hill, hillock, or less commonly a short ridge of stratified drift; but several or many are often associated, giving rise to groups and areas of _kames_. kames are often associated with terminal moraines, a relation which emphasizes the fact of their marginal origin. so far as the superficial streams which flowed to the edge of the ice carried debris, this was subject to deposition as the streams descended from the ice. such drift would tend to increase the body of marginal stratified drift from subglacial sources. marginal accumulations of stratified drift, made by the co-operation of running water and ice, must have had their most extensive development, other things being equal, where the margin of the ice was longest in one position, and where the streams were heavily loaded. the deposits made by water at the edge of the ice differ from those of the next class--made beyond the edge of the ice--in that they were influenced in their disposition and present topography, by the presence of ice. in the devil's lake region isolated and well-defined kames are not of common occurrence. there are, however, at many points hills which have something of a kame-like character. there is such a hill a mile southeast of the court house at baraboo, at the point marked p, plate xxxvii. in this hill there are good exposures which show its structure. there are many hillocks of a general kame-like habit associated with the terminal moraine south of the main quartzite range, and north of the wisconsin river. many of them occur somewhat within the terminal moraine a few miles northwest of merrimac. _b. beyond the edge of the ice, on land._--as the waters escaping from the ice flowed farther, deposits of stratified drift were made quite beyond the edge of the ice. the forms assumed by such deposits are various, and depended on various conditions. where the waters issuing from the edge of the ice found themselves concentrated in valleys, and where they possessed sufficient load, and not too great velocity, they aggraded the valleys through which they flowed, developing fluvial plains of gravel and sand, which often extended far beyond the ice. such fluvial plains of gravel and sand constitute the _valley trains_ which extend beyond the unstratified glacial drift in many of the valleys of the united states. they are found especially in the valleys leading out from the stouter terminal moraines of late glacial age. from these moraines, the more extensive valley trains take their origin, thus emphasizing the fact that they are deposits made by water beyond a stationary ice margin. valley trains have all the characteristics of alluvial plains built by rapid waters carrying heavy loads of detritus. now and then their surfaces present slight variations from planeness, but they are minor. like all plains of similar origin they decline gradually, and with diminishing gradient, down stream. they are of coarser material near their sources, and of finer material farther away. valley trains constitute a distinct topographic as well as genetic type. a perfect example of a valley train does not occur within the region here discussed. there is such a train starting at the moraine where it crosses the wisconsin river above prairie du sac, and extending down that valley to the mississippi, but at its head this valley train is wide and has the appearance of an overwash plain, rather than a valley train. farther from the moraine, however, it narrows, and assumes the normal characteristics of a valley train. it is the gravel and sand of this formation which underlies sauk prairie, and its topographic continuation to the westward. where the subglacial streams did not follow subglacial valleys, they did not always find valleys when they issued from the ice. under such circumstances, each heavily loaded stream coming out from beneath the ice must have tended to develop a plain of stratified material near its point of issue--a sort of alluvial fan. where several such streams came out from beneath the ice near one another, their several plains, or fans, were likely to become continuous by lateral growth. such border plains of stratified drift differ from valley trains particularly ( ) in being much less elongate in the direction of drainage; ( ) in being much more extended parallel to the margin of the ice; and ( ) in not being confined to valleys. such plains stood an especially good chance of development where the edge of the ice remained constant for a considerable period of time, for it was under such conditions that the issuing waters had opportunity to do much work. thus arose the type of stratified drift variously known as _overwash plains_, _outwash plains_, _morainic plains_, and _morainic aprons_. these plains sometimes skirt the moraine for many miles at a stretch. overwash plains may sometimes depart from planeness by taking on some measure of undulation, of the sag and swell (kame) type, especially near their moraine edges. the same is often true of the heads of valley trains. the heads of valley trains and the inner edges of overwash plains, it is to be noted, occupy the general position in which kames are likely to be formed, and the undulations which often affect these parts of the trains and plains, respectively, are probably to be attributed to the influence of the ice itself. valley trains and overwash plains, therefore, at their upper ends and edges respectively, may take on some of the features of kames. indeed, either may head in a kame area. good examples of overwash or outwash plains may be seen at various points in the vicinity of baraboo. the plain west of the moraine just south of the main quartzite ridge has been referred to under valley trains. in sauk prairie, however, its characteristics are those of an outwash plain, rather than those of a valley train. [illustration: fig. .--the morainic or outwash plain bordering the terminal moraine. the figure is diagrammatic, but represents, in cross section, the normal relation as seen south of the quartzite range at the east edge of sauk prairie, north of the baraboo river and at some points between the south range and the baraboo.] a good example of an outwash plain occurs southwest of baraboo, flanking the moraine on the west (fig. ). seen from the west, the moraine just north of the south quartzite range stands up as a conspicuous ridge twenty to forty feet above the morainic plain which abuts against it. traced northward, the edge of the outwash plain, as it abuts against the moraine, becomes higher, and in section , township n., range e., the moraine edge of the plain reaches the crest of the moraine (fig. ). from this point north to the baraboo river the moraine scarcely rises above the edge of the outwash beyond. [illustration: fig. .--the outwash plain is built up to the crest of the moraine. the figure is diagrammatic, but this relation is seen at the point marked w, plate ii.] north of the baraboo river the moraine is again distinct and the overwash plain to the west well developed much of the way from the baraboo to kilbourn city. a portion of it is known as webster's prairie. locally, the outwash plains of this region have been much dissected by erosion since their deposition, and are now affected by many small valleys. in composition these plains are nearly everywhere gravel and sand, the coarser material being nearer the moraine. the loose material is in places covered by a layer of loam several feet deep, which greatly improves the character of the soil. this is especially true of sauk prairie, one of the richest agricultural tracts in the state. when the waters issuing from the edge of the ice were sluggish, whether they were in valleys or not, the materials which they carried and deposited were fine instead of coarse, giving rise to deposits of silt, or clay, instead of sand or gravel. at many points near the edge of the ice during its maximum stage of advance, there probably issued small quantities of water not in the form of well-defined streams, bearing small quantities of detritus. these small quantities of water, with their correspondingly small loads, were unable to develop considerable plains of stratified drift, but produced small patches instead. such patches have received no special designation. in the deposition of stratified drift beyond the edge of the ice, the latter was concerned only in so far as its activity helped to supply the water with the necessary materials. _c. deposits at and beyond the edge of the ice in standing water._--the waters which issued from the edge of the ice sometimes met a different fate. the ice in its advance often moved up river valleys. when at the time of its maximum extension, it filled the lower part of a valley, leaving the upper part free, drainage through the valley stood good chance of being blocked. where this happened a marginal valley lake was formed. such a lake was formed in the valley of the baraboo when the edge of the ice lay where the moraine now is (plate ii). the waters which were held back by the ice dam, reinforced by the drainage from the ice itself, soon developed a lake above the point of obstruction. this extinct lake may be named baraboo lake. in this lake deposits of laminated clay were made. they are now exposed in the brick yards west of baraboo, and in occasional gullies and road cuts in the flat bordering the river. at the point marked s (plate xxxvii) there was, in glacial times, a small lake having an origin somewhat different from that of baraboo lake. the former site of the lake is now marked by a notable flat. excavations in the flat show that it is made up of stratified clay, silt, sand and gravel, to the depth of many feet,--locally more than sixty. these lacustrine deposits are well exposed in the road cuts near the northwest corner of the flat, and in washes at some other points. plate xxxviii shows some of the silt and clay, the laminæ of which are much distorted. _deltas_ must have been formed where well-defined streams entered the lakes, and _subaqueous overwash plains_ where deltas became continuous by lateral growth. the accumulation of stratified drift along the ice-ward shores of such lakes must have been rapid, because of the abundant supply of detritus. these materials were probably shifted about more or less by waves and shore currents, and some of them may have been widely distributed. out from the borders of such lakes, fine silts and clays must have been in process of deposition, at the same time that the coarse materials were being laid down nearer shore. [illustration: wisconsin geol. and nat. hist. survey. bulletin no. v., pl. xxxviii. distorted laminae of silt and clay.] good examples of deltas and subaqueous overwash plains do not appear to exist in the region, although conditions for their development seem to have been present. thus in the lake which occupied the valley of the baraboo, conditions would seem to have been ideal for the development of such features; that is, the overwash plains previously described should, theoretically, have been subaqueous overwash plains; but if this be their character, their distinctive marks have been destroyed by subsequent erosion. during the maximum extension of an ice sheet, therefore, there was chance for the development, at its edge or beyond it, of the following types of stratified drift: ( ) kames and kame belts, at the edge of the ice; ( ) fluvial plains or valley trains, in virtual contact with the ice at their heads; ( ) border plains or overwash plains, in virtual contact with the ice at their upper edges; ( ) ill-defined patches of stratified drift, coarse or fine near the ice; ( ) subaqueous overwash plains and deltas, formed either in the sea or lakes at or near the edge of the ice; ( ) lacustrine and marine deposits of other sorts, the materials for which were furnished by the waters arising from the ice. so far as this region is concerned, all the deposits made in standing water were made in lakes. _deposits made by extraglacial waters during the retreat of the ice._ during the retreat of any ice sheet, disregarding oscillations of its edge, its margin withdrew step by step from the position of extreme advance to its center. when the process of dissolution was complete, each portion of the territory once covered by the ice, had at some stage in the dissolution, found itself in a marginal position. at all stages in its retreat the waters issuing from the edge of the ice were working in the manner already outlined in the preceding paragraphs. two points of difference only need be especially noted. in the first place the deposits made by waters issuing from the retreating ice were laid down on territory which the ice had occupied, and their subjacent stratum was often glacial drift. so far as this was the case, the stratified drift was super-morainic, not extra-morainic. in the second place the edge of the ice in retreat did not give rise to such sharply marked formations as the edge of the ice which was stationary. the processes which had given rise to valley trains, overwash plains, kames, etc., while the ice edge was stationary, were still in operation, but the line or zone of their activity (the edge of the ice) was continually retreating, so that the foregoing types, more or less dependent on a stationary edge, were rarely well developed. as the ice withdrew, therefore, it allowed to be spread over the surface it had earlier occupied, many incipient valley trains, overwash plains, and kames, and a multitude of ill-defined patches of stratified drift, thick and thin, coarse and fine. wherever the ice halted in its retreat, these various types stood chance of better development. such deposits did not cover all the surface discovered by the ice in its retreat, since the issuing waters, thanks to their great mobility, concentrated their activities along those lines which favored their motion. nevertheless the aggregate area of the deposits made by water outside the ice as it retreated, was great. it is to be noted that it was not streams alone which were operative as the ice retreated. as its edge withdrew, lakes and ponds were continually being drained, as their outlets, hitherto choked by the ice, were opened, while others were coming into existence as the depressions in the surface just freed from ice, filled with water. lacustrine deposits at the edge of the ice during its retreat were in all essential respects identical with those made in similar situations during its maximum extension. disregarding oscillations of the ice edge at these stages, the deposits made by extraglacial waters during the maximum extension of an ice sheet, and during its retreat, were always left at the surface, so far as the work of that ice sheet was concerned. the stratified drift laid down by extraglacial waters in these stages of the last ice sheet which affected any region of our continent still remain at the surface in much the condition in which they were deposited, except for the erosion they have since suffered. it is because of their position at the surface that the deposits referable to these stages of the last ice sheet of any given region have received most attention and are therefore most familiar. _deposits made by extraglacial waters during the advance of the ice._ during the advance of an ice sheet, if its edge forged steadily forward, the waters issuing from it, and flowing beyond, were effecting similar results. they were starting valley trains, overwash plains, kames, and small ill-defined patches of stratified drift which the ice did not allow them to complete before pushing over them, thus moving forward the zone of activity of extraglacial waters. unlike the deposits made by the waters of the retreating ice, those made by the waters of the advancing stage were laid down on territory which had not been glaciated, or at least not by the ice sheet concerned in their deposition. if the ice halted in its advance, there was at such time and place opportunity for the better development of extraglacial stratified drift. lakes as well as streams were concerned in the making of stratified beds of drift, during the advance of the ice. marginal lakes were obliterated by having their basins filled with the advancing ice, which displaced the water. but new ones were formed, on the whole, as rapidly as their predecessors became extinct, so that lacustrine deposits were making at intervals along the margin of the advancing ice. deposits made in advance of a growing ice sheet, by waters issuing from it, were subsequently overridden by the ice, to the limit of its advance, and in the process, suffered destruction, modification, or burial, in whole or in part, so that now they rarely appear at the surface. _deposits made by subglacial streams._ before their issuance from beneath the ice, subglacial waters were not idle. their activity was sometimes erosive, and at such times stratified deposits were not made. but where the sub-glacial streams found themselves overloaded, as seems frequently to have been the case, they made deposits along their lines of flow. where such waters were not confined to definite channels, their deposits probably took on the form of irregular patches of silt, sand, or gravel; but where depositing streams were confined to definite channels, their deposits were correspondingly concentrated. when subglacial streams were confined to definite channels, the same may have been constant in position, or may have shifted more or less from side to side. where the latter happened there was a tendency to the development of a belt or strip of stratified drift having a width equal to the extent of the lateral migrations of the under-ice stream. where the channel of the subglacial stream remained fixed in position, the deposition was more concentrated, and the bed was built up. if the stream held its course for a long period of time, the measure of building may have been considerable. in so far as these channel deposits were made near the edge of the ice, during the time of its maximum extension or retreat, they were likely to remain undisturbed during its melting. the aggraded channels then came to stand out as ridges. these ridges of gravel and sand are known as osars or eskers. it is not to be inferred that eskers never originated in other ways, but it seems clear that this is one method, and probably the principal one, by which they came into existence. eskers early attracted attention, partly because they are relatively rare, and partly because they are often rather striking topographic features. the essential conditions, therefore, for their formations, so far as they are the product of subglacial drainage, are ( ) the confining of the subglacial streams to definite channels; and ( ) a sufficient supply of detritus. one esker only has been found in the region under consideration. it is located at the point marked j, plate ii, seven and one-half miles northeast of merrimac and one and one-half miles south of alloa (g, plate ii). the esker is fully a quarter of a mile long, about thirty feet high, and four rods wide at its base. subglacial deposits of stratified drift were sometimes made on unstratified drift (till) already deposited by the ice before the location of the stream, and sometimes on the rock surfaces on which no covering of glacier drift had been spread. it is to be kept in mind that subglacial drainage was operative during the advance of an ice sheet, during its maximum extension, and during its retreat, and that during all these stages it was effecting its appropriate results. it will be readily seen, however, that all deposits made by subglacial waters, were subject to modification or destruction or burial, through the agency of the ice, and that those made during the advance of the ice were less likely to escape than those made during its maximum extension or retreat. relations of stratified to unstratified drift. when it is remembered that extraglacial and subglacial waters were active at all stages of an ice sheet's history, giving rise, or tending to give rise to all the phases of stratified drift enumerated above; when it is remembered that the ice of several epochs affected much of the drift-covered country; and when it is remembered further that the edge of the ice both during advance and retreat was subject to oscillation, and that each advance was likely to bury the stratified drift last deposited, beneath unstratified, it will be seen that the stratified drift and the unstratified had abundant opportunity to be associated in all relationships and in all degrees of intimacy, and that the relations of the one class of drift to the other may come to be very complex. as a result of edge oscillation, it is evident that stratified drift may alternate with unstratified many times in a formation of drift deposited during a single ice epoch, and that two beds of till, separated by a bed of stratified drift, do not necessarily represent two distinct glacial epochs. the extent of individual beds of stratified drift, either beneath the till or inter-bedded with it, may not be great, though their aggregate area and their aggregate volume is very considerable. it is to be borne in mind that the ice, in many places, doubtless destroyed all the stratified drift deposited in advance on the territory which it occupied later, and that in others it may have left only patches of once extensive sheets. this may help to explain why it so frequently happens that a section of drift at one point shows many layers of stratified drift, while another section close by, of equal depth, and in similar relationships, shows no stratified material whatsoever. such deposits as were made by superglacial streams during the advance of the ice must likewise have been delivered on the land surface, but would have been subsequently destroyed or buried, becoming in the latter case, submorainic. this would be likely to be the fate of all such superglacial gravels as reached the edge of the ice up to the time of its maximum advance. streams descending from the surface of the ice into crevasses also must have carried down sand and gravel where such materials existed on the ice. these deposits may have been made on the rock which underlies the drift, or they may have been made on stratified or unstratified drift already deposited. in either case they were liable to be covered by till, thus reaching an inter-till or sub-till position. englacial streams probably do little depositing, but it is altogether conceivable that they might accumulate such trivial pockets of sand and gravel as are found not infrequently in the midst of till. the inter-till position would be the result of subsequent burial after the stratified material reached a resting place. complexity of relations.--from the foregoing it becomes clear that there are diverse ways by which stratified drift, arising in connection with an ice sheet, may come to be interbedded with till, when due recognition is made of all the halts and oscillations to which the edge of a continental glacier may have been subject during both its advance and retreat. classification of stratified drift on the basis of position. in general the conditions and relations which theoretically should prevail are those which are actually found. on the basis of position stratified drift deposits may be classified as follows: . extraglacial deposits, made by the waters of any glacial epoch if they flowed and deposited beyond the farthest limit of the ice. . supermorainic deposits, made chiefly during the final retreat of the ice from the locality where they occur, but sometimes by extraglacial streams or lakes of a much later time. locally too, stratified deposits of an early stage of a glacial epoch, lying on till, may have failed to be buried by the subsequent passage of the ice over them, and so remain at the surface. in origin, supermorainic deposits were for the most part extraglacial (including marginal), so far as the ice sheet calling them into existence was concerned. less commonly they were subglacial, and failed to be covered, and less commonly still superglacial. . the submorainic (basal) deposits were made chiefly by extraglacial waters in advance of the first ice which affected the region where they occur. they were subsequently overridden by the ice and buried by its deposits. submorainic deposits, however, may have arisen in other ways. subglacial waters may have made deposits of stratified drift on surfaces which had been covered by ice, but not by till, and such deposits may have been subsequently buried. the retreat of an ice sheet may have left rock surfaces free from till covering, on which the marginal waters of the ice may have made deposits of stratified drift. these may have been subsequently covered by till during a re-advance of the ice in the same epoch or in a succeeding one. still again, the till left by one ice sheet may have been exposed to erosion to such an extent as to have been completely worn away before the next ice advance, so that stratified deposits connected with a second or later advance may have been made on a driftless surface, and subsequently buried. . intermorainic stratified drift may have originated at the outset in all the ways in which supermorainic drift may originate. it may have become intermorainic by being buried in any one of the various ways in which the stratified drift may become submorainic. changes in drainage effected by the ice. _while the ice was on._ as the continental ice sheet invaded a region, the valleys were filled and drainage was thereby seriously disturbed. different streams were affected in different ways. where the entire basin of a stream was covered by ice, the streams of that basin were, for the time being, obliterated. where the valley of a stream was partially filled with ice, the valley depression was only partially obliterated, and the remaining portion became the scene of various activities. where the ice covered the lower course of a stream but not the upper, the ice blocked the drainage, giving rise to a lake. where the ice covered the upper course of a stream, but not its lower, the lower portion was flooded, and though the river held its position, it assumed a new phase of activity. streams issuing from the ice usually carry great quantities of gravel and sand, and make deposits along their lower courses. long continued glacial drainage usually results in a large measure of aggradation. this was true of the streams of the glacial period. where a stream flowed parallel or approximately parallel to the edge of the advancing ice it was sometimes shifted in the direction in which the ice was moving, keeping parallel to the front of the ice. all of these classes of changes took place in this region. _wisconsin lake._--reference has already been made to certain lakes which existed in the region when the ice was there. the largest of these lakes was that which resulted from the blocking of the wisconsin river. the ice crossed its present course at kilbourn city, and its edge lay to the west of the river from that point to prairie du sac (see plate i). the waters from the area now draining into the wisconsin must either have found an avenue of escape beneath the ice, or have accumulated in a lake west of the edge of the ice. there is reason to believe that the latter was what happened, and that a great lake covered much of the low land west of the wisconsin river above and below kilbourn city. the extensive gravel beds on the north flank of the quartzite bluff at necedah, and the water-worn pebbles of local origin on the slope of petenwell peak (plate xxxii), as well as the gravels at other points, are presumably the work of that lake. the waters in this lake, as in that in the baraboo valley, probably rose until the lowest point in the rim of the basin was reached, and there they had their outlet. the position of this outlet has not been definitely determined, but it has been thought to be over the divide of the black river.[ ] it is possible, so far as now known, that this lake was connected with that of the baraboo valley. until topographic maps of this region are made, the connections will not be easily determined. [ ] chamberlin: geology of wisconsin, vol. . even after the ice had retreated past the wisconsin, opening up the present line of drainage, the lakes did not disappear at once, for the ice had left considerable deposits of drift in the wisconsin valley. thus at f, plates ii and xxxvii, and perhaps at other points, the wisconsin has made cuts of considerable depth in the drift. were these cuts filled, as they must have been when the ice melted, the drainage would be ponded, the waters standing at the level of the dam. this drift obstruction at f would therefore have prolonged the history of the lake which had come into existence when the ice blocked the drainage of the wisconsin. as the drift of the valley was removed the level of the lake sank and finally disappeared. _baraboo lake._--another lake which existed in this region when the ice was here, occupied the valley of the baraboo and its tributaries when the ice blocked the valley at baraboo. this lake occupied not only the valley of the baraboo, but extended up the lower course of every tributary, presumably rising until it found the lowest point in the rim of the drainage basin. the location of this point, and therefore the height of the lake when at its maximum, are not certainly known, though meager data on this point have been collected. at a point three miles southeast of ablemans on the surface of a sandstone slope, water-worn gravel occurs, the pebbles of which were derived from the local rock. on the slope below the gravel, the surface is covered with loam which has a suggestion of stratification, while above it, the soil and subsoil appear to be the product of local rock decomposition. this water-worn gravel of local origin on a steep slope facing the valley, probably represents the work of the waves of this lake, perhaps when it stood at its maximum height. this gravel is about feet (aneroid measurement) above the baraboo river to the north. further evidence of a shore line has been found at the point marked t, plate ii. at this place water-worn gravel of the local rock occurs in much the same relationship as that already mentioned, and at the same elevation above the baraboo river. at a point two and one-half miles southwest of ablemans there is local water-worn gravel, with which is mingled glacial material (pieces of porphyry and diabase) which could have reached this point only by being carried thither by floating ice from the glacier. the level of this mixed local and glacial material is (according to aneroid measurement) approximately the same as that of the other localities. when the ice melted, an outlet was opened _via_ the lower narrows, and the water of the lake drained off to the wisconsin by this route. had the ice left no drift, the lake would have been promptly drained when the ice melted; but the lake did not entirely disappear immediately after the ice retreated, for the drift which the ice left obstructed drainage to the east. the moraine, however, was not so high as the outlet of the lake while the ice was on, so that, as the ice retreated, the water flowed over the moraine to the east, and drew down the level of the lake to the level of the lowest point in the moraine. the postglacial cut through the moraine is about ninety feet deep. besides being obstructed where crossed by the terminal moraine, the valley of the baraboo was clogged to a less extent by drift deposits between the moraine and the lower narrows. at one or two places near the city of baraboo, such obstructions, now removed, appear to have existed. just above the lower narrows (c, plate xxxvii) there is positive evidence that the valley was choked with drift. here in subsequent time, the river has cut through the drift-filling of the preglacial valley, developing a passage about twenty rods wide and thirty-five feet deep. if this passage were filled with drift, reproducing the surface left by the ice, the broad valley above it would be flooded, producing a shallow lake. the retreat of the ice therefore left two well defined drift dams in the valley, one low one just above the lower narrows, and a higher one, the moraine dam, just west of baraboo. disregarding the influence of the ice, and considering the baraboo valley only, these two dams would have given rise to two lakes, the upper one behind the higher dam being deeper and broader, and covering a much larger area; the lower one behind the lower dam, being both small and shallow. up to the time that the ice retreated past the lower narrows, the waters of the upper and lower lakes were united, held up to a common level by the ice which blocked this pass. after the ice retreated past the lower narrows, the level of the baraboo lake did not sink promptly, for not until the ice had retreated past the site of the wisconsin was the present drainage established. meantime the waters of the baraboo lake joined those of wisconsin lake through the lower narrows. if the lakes had been before connected at some point farther west, this connection through the narrows would not have changed the level of either. if they were not before connected, and if the wisconsin lake was lower than the baraboo, this connection would have drawn down the level of the latter. since the drainage from the baraboo went to the wisconsin, the baraboo lake was not at first lowered below the level of the highest obstruction in the valley of the wisconsin even after the ice had retreated beyond that stream. as the drift obstructions of the wisconsin valley were lowered, the levels of all the lakes above were correspondingly brought down. when the level of the waters in these lakes was brought down to the level of the moraine dam above baraboo, the one baraboo lake of earlier times became two. the level of the upper of these two lakes was determined by the moraine above baraboo, that of the lower by the highest obstruction below the moraine in either the baraboo or wisconsin valley. the drift obstructions in the baraboo valley were probably removed about as fast as those in the wisconsin, and since the obstructions were of drift, and the streams strong, the removal of the dams was probably rapid. both the upper and lower baraboo lakes, as well as the wisconsin, had probably been reduced to small proportions, if not been completely drained, before the glacial period was at an end. _devil's lake in glacial times._--while the ice edge was stationary in its position of maximum advance, its position on the north side of the main quartzite range was just north of devil's lake (plate xxxvii). the high ridge of drift a few rods north of the shore is a well defined moraine, and is here more clearly marked than farther east or west, because it stands between lower lands on either side, instead of being banked against the quartzite ridge. north of the lake it rises about feet above the water. when the ice edge lay in this position on the north side of the range, its front between the east bluff and the devil's nose lay a half mile or so from the south end of the lake. in this position also there is a well defined moraine. while the ice was at its maximum stand, it rose above these moraine ridges at either end of the lake. between the ice at these two points there was then a notable basin, comparable to that of the present lake except that the barriers to the north and southeast were higher than now. the melting of the ice supplied abundant water, and the lake rose above its present level. the height which it attained is not known, but it is known to have risen at least feet above its present level. this is indicated by the presence of a few drift bowlders on the west bluff of the lake at this height. they represent the work of a berg or bergs which at some stage floated out into the lake with bowlders attached. bowlders dropped by bergs might be dropped at any level lower than the highest stand of the lake. _other lakes._--another glacial lake on the east quartzite bluff has already been referred to. like the devil's lake in glacial time, its basin was an enclosure between the ice on the one hand, and the quartzite ridge on the other. the location of this lake is shown on plate xxxvii (s). here the edge of the ice, as shown by the position of the moraine, was affected by a re-entrant curve, the two ends of which rested against the quartzite ridge. between the ice on the one hand and the quartzite ridge on the other, a small lake was formed. its position is marked by a notable flat. with the exception of the north side, and a narrow opening at the northwest corner, the flat is surrounded by high lands. when the ice occupied the region, its edge held the position shown by the line marking the limit of its advance, and constituted an ice barrier to the north.[ ] the area of the flat was, therefore, almost shut in, the only outlet being a narrow one at t, plate xxxvii. if the filling of stratified drift which underlies the flat were removed, the bottom of the area would be much lower than at present, and much lower than the outlet at t. it is therefore evident that when the ice had taken its position along the north side of the flat, an enclosed basin must have existed, properly situated for receiving and holding water. since this lake had but a short life and became extinct before the ice retreated, its history is here given. [ ] the moraine line on the map represents the crest of the marginal ridge rather than its outer limit, which is slightly nearer the lake margin. stratified drift of the nature of overwash also intervenes at points between the moraine and the lake border. at first the lake had no outlet and the water rose to the level of the lowest point (t) in the rim of the basin, and thence overflowed to the west. meanwhile the sediments borne in by the glacial drainage were being deposited in the lake in the form of a subaqueous overwash plain, the coarser parts being left near the shore, while the finer were carried further out. continued drainage from the ice continued to bring sediment into the lake, and the subaqueous overwash plain extended its delta-like front farther and farther into the lake, until its basin was completely filled. with the filling of the basin the lake became extinct. the later drainage from the ice followed the line of the outlet, the level of which corresponds with the level of the filled lake basin. this little extinct lake is of interest as an example of a glacial lake which became extinct by having its basin filled during glacial times, by sediments washed out from the ice. near the northwest corner of this flat, an exposure in the sediments of the old lake bed shows the curiously contorted layers of sand, silt, and clay represented in plate xxxviii. the layers shown in the figure are but a few feet below the level of the flat which marks the site of the lake. it will be seen that the contorted layers are between two series of horizontal ones. the material throughout the section is made up of fine-grained sands and clays, well assorted. that these particular layers should have been so much disturbed, while those below and above remained horizontal, is strange enough. the grounding of an iceberg on the surface before the overlying layers were deposited, the action of lake ice, or the effect of expansion and contraction due to freezing and thawing, may have been responsible for the singular phenomenon. contorted laminæ are rather characteristic of the deposits of stratified drift. _after the ice had disappeared._ as has already been indicated, the irregular deposition of glacial drift gave rise to many depressions without outlets in which surface waters collected after the ice had disappeared, forming ponds or lakes. so abundant are lakes and ponds and marshes in recently glaciated regions and so rare elsewhere, that they constitute one of the more easily recognized characteristics of a glaciated region. after the ice had melted, the mantle of drift which it left was sometimes so disposed as to completely obliterate preglacial valleys. more commonly it filled preglacial valleys at certain points only. in still other cases a valley was not filled completely at any point, though partially at many. in this last case, the partial fillings at various points constituted dams above which drainage was ponded, making lakes. if the dams were not high enough to throw the drainage out of the valley, the lakes would have their outlets over them. the drift dam being unconsolidated would be quickly cut down by the outflowing water, and the lake level lowered. when the dam was removed or cut to its base, the lake disappeared and drainage followed its preglacial course. in case the valley was completely filled, or completely filled at points, the case was very different. the drainage on the drift surface was established with reference to the topography which obtained when the ice departed, and not with reference to the preglacial valleys. wherever the preglacial valleys were completely filled, the postglacial drainage followed lines which were altogether independent of them. when preglacial valleys were filled by the drift in spots only, the postglacial streams followed them where they were not filled, only to leave them where the blocking occurred. in the former case the present drainage is through valleys which are preglacial in some places, and postglacial in others. thus the drainage changes effected by the drift after the ice was gone, concerned both lakes and rivers. in this region there are several illustrations of these changes. _lakes._--the lake basins of drift-covered regions are of various types. some of them are altogether in drift, some partly in drift and partly in rock, and some wholly in rock. basins in the drift were likely to be developed whenever heavy deposits surrounded thin ones. they are especially common in the depressions of terminal moraines. another class of lake basins occurs in valleys, the basins being partly rock and partly drift. if a thick deposit of drift be made at one point in a valley, while above there is little or none, the thick deposit will form a dam, above which waters may accumulate, forming a pond or lake. again, a ridge of drift may be deposited in the form of a curve with its ends against a rock-ridge, thus giving rise to a basin. in the course of time, the lakes and ponds in the depressions made or occasioned by the drift will be destroyed by drainage. remembering how valleys develop it is readily understood that the heads of the valleys will sooner or later find the lakes, and drain them if their bottoms be not too low. drainage is hostile to lakes in another way. every stream which flows into a lake brings in more or less sediment. in the standing water this sediment is deposited, thus tending to fill the lake basin. both by filling their basins and by lowering their outlets, rivers tend to the destruction of lakes, and given time enough, they will accomplish this result. in view of this double hostility of streams, it is not too much to say that "rivers are the mortal enemies of lakes." the destruction of lakes by streams is commonly a gradual process, and so it comes about that the abundance and the condition of the undrained areas in a drift-covered region is in some sense an index of the length of time, reckoned in terms of erosion, which has elapsed since the drift was deposited. in this region there were few lakes which lasted long after the ice disappeared. the basins of the baraboo and wisconsin lakes were partly of ice, and so soon as the ice disappeared, the basins were so nearly destroyed, and the drift dams that remained so easily eroded, that the lakes had but a brief history,--a history that was glacial, rather than postglacial. the history of the little lake on the east quartzite bluff as already pointed out, came to an end while the ice was still present. the beds of at least two other extinct ponds or small lakes above the level of the baraboo are known. these are at v and w, plate xxxvii. they owed their origin to depressions in the drift, but the outflowing waters have lowered their outlets sufficiently to bring them to the condition of marshes. both were small in area and neither was deep. _existing lakes._--relatively few lakes now remain in this immediate region, though they are common in most of the country covered by the ice sheet which overspread this region. devil's lake only is well known. the lake which stood in this position while the ice was on, has already been referred to. after the ice had melted away, the drift which it had deposited still left an enclosure suitable for holding water. the history of this basin calls for special mention. at the north end of the lake, and again in the capacious valley leading east from its south end, there are massive terminal moraines. followed southward, this valley though blocked by the moraine a half mile below the lake, leads off towards the wisconsin river, and is probably the course of a large preglacial stream. beyond the moraine, this valley is occupied by a small tributary to the wisconsin which heads at the moraine. to the north of the lake, the head of a tributary of the baraboo comes within eighty rods of the lake, but again the terminal moraine intervenes. from data derived from wells it is known that the drift both at the north and south ends of the lake extends many feet below the level of its water, and at the north end, the base of the drift is known to be at least fifty feet below the level of the bottom of the lake. the draining of devil's lake to the baraboo river is therefore prevented only by the drift dam at its northern end. it is nearly certain also, that, were the moraine dam at the south end of the lake removed, all the water would flow out to the wisconsin, though the data for the demonstration of this conclusion are not to be had, as already stated. there can be no doubt that the gorge between the east and west bluffs was originally the work of a pre-cambrian stream, though the depth of the pre-cambrian valley may not have been so great as that of the present. later, the valley, so far as then excavated, was filled with the cambrian (potsdam) sandstone, and re-excavated in post-cambrian and preglacial time. devil's lake then occupies an unfilled portion of an old river valley, isolated by great morainic dams from its surface continuations on either hand. between the dams, water has accumulated and formed the lake. _changes in streams._ in almost every region covered by the ice, the streams which established themselves after its departure follow more or less anomalous courses. this region is no exception. illustrations of changes which the deposition of the drift effected have already been given in one connection or another in this report. _skillett creek._--an illustration of the sort of change which drift effects is furnished by skillett creek, a small stream tributary to the baraboo, southwest of the city of that name. for some distance from its head (a to b, fig. ) its course is through a capacious preglacial valley. the lower part of this valley was filled with the water-laid drift of the overwash plain. on reaching the overwash plain the creek therefore shifted its course so as to follow the border of that plain, and along this route, irrespective of material, it has cut a new channel to the baraboo. the postglacial portion of the valley (b to c) is everywhere narrow, and especially so where cut in sandstone. the course and relations of this stream suggest the following explanation: before the ice came into the region, skillett creek probably flowed in a general northeasterly direction to the baraboo, through a valley comparable in size to the preglacial part of the present valley. as the ice advanced, the lower part of this valley was occupied by it, and the creek was compelled to seek a new course. the only course open to it was to the north, just west of the advancing ice, and, shifting westward as fast as the ice advanced, it abandoned altogether its former lower course. drainage from the ice then carried out and deposited beyond the same, great quantities of gravel and sand, making the overwash plain. this forced the stream still farther west, until it finally reached its present position across a sandstone ridge or plain, much higher than its former course. into this sandstone it has since cut a notable gorge, a good illustration of a postglacial valley. the series of changes shown by this creek is illustrative of the changes undergone by streams in similar situations and relations all along the margin of the ice. [illustration: fig. .--skillett creek, illustrating the points mentioned in the text.] the picturesque glens (parfrey's and dorward's) on the south face of the east bluff are the work of post-glacial streams. the preglacial valleys of this slope were obliterated by being filled during the glacial epoch. _the wisconsin._--the preglacial course of the wisconsin river is not known in detail, but it was certainly different from the course which the stream now follows. on plate i the relations of the present stream to the moraine (and former ice-front) may be seen.[ ] as the ice approached it from the east, the preglacial valley within the area here under consideration was affected first by the overwash from the moraine, and later by the ice itself, from the latitude of kilbourn city to prairie du sac. [ ] the preglacial course was probably east of the present in the vicinity of kilbourn city. it has already been stated that the ice probably dammed the river, and that a lake was formed above kilbourn city, reaching east to the ice and west over the lowland tributary to the river, the water rising till it found an outlet, perhaps down to the black river valley. when the ice retreated, the old valley had been partly filled, and the lowest line of drainage did not everywhere correspond with it. where the stream follows its old course, it flows through a wide capacious valley, but where it was displaced, it found a new course on the broad flat which bordered its preglacial course. displacement of the stream occurred in the vicinity of kilbourn city, and, forced to find a new line of flow west of its former course, the stream has cut a new channel in the sandstone. to this displacement of the river, and its subsequent cutting, we are indebted for the far-famed dalles of the wisconsin. but not all the present route of the river through the dalles has been followed throughout the entire postglacial history of the stream. in fig. , the depression a, b, c, was formerly the course of the stream. the present course between d and e is therefore the youngest portion of the valley, and from its lesser width is known as the "narrows." during high water in the spring, the river still sends part of its waters southward by the older and longer route. the preglacial course of the wisconsin south of the dalles has never been determined with certainty, but rational conjectures as to its position have been made. the great gap in the main quartzite range, a part of which is occupied by devil's lake, was a narrows in a preglacial valley. the only streams in the region sufficiently large to be thought of as competent to produce such a gorge are the baraboo and the wisconsin. if the baraboo was the stream which flowed through this gorge in preglacial time, the comparable narrows in the north quartzite range--the lower narrows of the baraboo--is to be accounted for. the stream which occupied one of these gorges probably occupied the other, for they are in every way comparable except in that one has been modified by glacial action, while the other has not. [illustration: fig. .--the wisconsin valley near kilbourn city.] the baraboo river flows through a gorge--the upper narrows--in the north quartzite range at ablemans, nine miles west of baraboo. this gorge is much narrower than either the lower narrows or the devil's lake gorge, suggesting the work of a lesser stream. it seems on the whole probable, as suggested by irving,[ ] that in preglacial time the wisconsin river flowed south through what is now the lower narrows of the baraboo, thence through the devil's lake gorge to its present valley to the south. if this be true, the baraboo must at that time have joined this larger stream at some point east of the city of the same name. [ ] irving. geology of wisconsin, vol. ii. _the driftless area._ reference has already been made to the fact that the western part of the area here described is driftless, and the line marking the limit of ice advance has been defined. beyond this line, gravel and sand, carried beyond the ice by water, extends some distance to the west. but a large area in the southwestern part of the state is essentially free from drift, though it is crossed by two belts of valley drift (valley trains) along the wisconsin and mississippi rivers. the "driftless area" includes, besides the southwestern portion of wisconsin, the adjoining corners of minnesota, iowa and illinois. in the earlier epochs of the glacial period this area was completely surrounded by the ice, but in the last or wisconsin epoch it was not surrounded, since the lobes did not come together south of it as in earlier times. (compare plate xxxiii and fig. .) various suggestions have been made in the attempt to explain the driftless area. the following is perhaps the most satisfactory:[ ] [ ] chamberlin and irving. geology of wisconsin, vols. i and ii. the adjacent highlands of the upper peninsula of michigan, are bordered on the north by the capacious valley of lake superior leading off to the west, while to the east lies the valley of lake michigan leading to the south. these lake valleys were presumably not so broad and deep in preglacial times as now, though perhaps even then considerable valleys. when the ice sheet, moving in a general southward direction from the canadian territory, reached these valleys, they led off two great tongues or lobes of ice, the one to the south through the lake michigan depression, the other to the south of west through the lake superior trough. (fig. .) the highland between the lake valleys conspired with the valleys to the same end. it acted as a wedge, diverting the ice to either side. it offered such resistance to the ice, that the thin and relatively feeble sheet which succeeded in surmounting it, did not advance far to the south before it was exhausted. on the other hand, the ice following the valleys of lakes superior and michigan respectively, failed to come together south of the highland until the latitude of northern iowa and illinois was reached. the driftless area therefore lies south of the highlands, beyond the limit of the ice which surmounted it, and between the superior and michigan glacial lobes above their point of union. the great depressions, together with the intervening highland, are therefore believed to be responsible for the absence of glaciation in the driftless area. _contrast between glaciated and unglaciated areas._ the glaciated and unglaciated areas differ notably in ( ) topography, ( ) drainage, and ( ) mantle rock. . _topography._--the driftless area has long been exposed to the processes of degradation. it has been cut into valleys and ridges by streams, and the ridges have been dissected into hills. the characteristic features of a topography fashioned by running water are such as to mark it clearly from surfaces fashioned by other agencies. rivers end at the sea (or in lakes). generally speaking, every point at the bottom of a river valley is higher than any other point in the bottom of the same valley nearer the sea, and lower than any other point correspondingly situated farther from the sea. this follows from the fact that rivers make their own valleys for the most part, and a river's course is necessarily downward. in a region of erosion topography therefore, tributary valleys lead down to their mains, secondary tributaries lead down to the first, and so on; or, to state the same thing in reverse order, in every region where the surface configuration has been determined by rain and river erosion, every gully and every ravine descends to a valley. the smaller valleys descend to larger and lower ones, which in turn lead to those still larger and lower. the lowest valley of a system ends at the sea, so that the valley which joins the sea is the last member of the series of erosion channels of which the ravines and gullies are the first. it will thus be seen that all depressions in the surface, worn by rivers, lead to lower ones. the surface of a region sculptured by rivers is therefore marked by valleys, with intervening ridges and hills, the slopes of which descend to them. all topographic features are here determined by the water courses. [illustration: fig. .--drainage in the driftless area. the absence of ponds and marshes is to be noted.] the relief features of the glaciated area, on the other hand, lack the systematic arrangement of those of the unglaciated territory, and stream valleys are not the controlling elements in the topography. . _drainage._--the surface of the driftless area is well drained. ponds and lakes are essentially absent, except where streams have been obstructed by human agency. the drainage of the drift-covered area, on the other hand, is usually imperfect. marshes, ponds and lakes are of common occurrence. these types are shown by the accompanying maps, figs. and , the one from the driftless area, the other from the drift-covered. [illustration: fig. .--drainage in a glaciated region. walworth and waukesha counties, wisconsin, showing abundance of marshes and lakes.] . _mantle rock._--the unglaciated surface is overspread to an average depth of several feet by a mantle of soil and earth which has resulted from the decomposition of the underlying rock. this earthy material sometimes contains fragments and even large masses of rock like that beneath. these fragments and masses escaped disintegration because of their greater resistance while the surrounding rock was destroyed. this mantle rock grades from fine material at the surface down through coarser, until the solid rock is reached, the upper surface of the rock being often ill-defined (fig. ). the thickness of the mantle is approximately constant in like topographic situations where the underlying rock is uniform. the residual soils are made up chiefly of the insoluble parts of the rock from which they are derived, the soluble parts having been removed in the process of disintegration. [illustration: fig. .--section in a driftless area, showing relation of the mantle rock to the solid rock beneath.] with these residuary soils of the driftless area, the mantle rock of glaciated tracts is in sharp contrast. here, as already pointed out, the material is diverse, having come from various formations and from widely separated sources. it contains the soluble as well as the insoluble parts of the rock from which it was derived. in it there is no suggestion of uniformity in thickness, no regular gradation from fine to coarse from the surface downward. the average thickness of the drift is also much greater than that of the residual earths. further, the contact between the drift and the underlying rock surface is usually a definite surface. (compare figs. and .) postglacial changes. since the ice melted from the region, the changes in its geography have been slight. small lakes and ponds have been drained, the streams whose valleys had been partly filled, have been re-excavating them, and erosion has been going on at all points in the slow way in which it normally proceeds. the most striking example of postglacial erosion is the dalles of the wisconsin, and even this is but a small gorge for so large a stream. the slight amount of erosion which has been accomplished since the drift was deposited, indicates that the last retreat of the ice, measured in terms of geology and geography, was very recent. it has been estimated at , to , years, though too great confidence is not to be placed in this, or any other numerical estimate of post-glacial time. index. -------------------------------------------------- pages ablemans , baraboo lake baraboo quartzite ranges , constitution of dynamic action in , , gaps in-- devil's lake gap , lower narrows , , narrows creek upper narrows , , , , igneous rock in structure of topography of , base-level base-level plains bowlder clay breccia castle rock cleopatra's needle cold water canyon conglomerate , basal (potsdam) corrasion cross-bedding cycle of erosion , dalles of the wisconsin origin of scenery of , dell creek deltas , , deposits-- by extra-glacial waters - by ice , by rivers , by subglacial streams of drift classified devil's doorway devil's lake history of in glacial times location , origin of devil's nose , divides, shifting of dorward's glen , , , drift characteristics of constitution of deposits classified effect on topography , relation of stratified to unstratified stratified topography of , driftless area , drainage-- adjustment of changes in, effected by the ice , establishment of glacial of drift-covered area of driftless area postglacial changes in endmoräne erosion-- by rain, and rivers, general outline of - elements of of folded strata of rocks of unequal hardness of the quartzite preglacial topography without valleys eskers falls fossils-- in limestone in sandstone , friendship mounds geographic features, general - glacial drainage glaciated area , , glacier ice-- deposition by direction of movement erosive work of - formation of movement of, affected by topography glens green bay lobe gibraltar rock ground moraine-- constitution of location of topography of groundwater level ice sheets-- formation of history of movement of , north american ice sheet igneous rock intermittent streams kames lakes-- wisconsin lake baraboo lake devil's lake , , , limestone, see lower magnesian. lower magnesian limestone-- fossils of history of - occurrence of origin of position of structure of lower narrows , , mantle rock , metamorphism , monadnocks moraines (see terminal moraine and ground moraine). morainic aprons narrows in quartzite , natural bridge navy yard niagara limestone north american ice sheet nunatak osars (see eskers). outwash plains , overwash plains , parfrey's glen , , , peneplain , pewit's nest , , pine hollow postglacial changes potsdam sandstone-- fossils of , history of - origin of - relation to quartzite structure of quartzite (see also baraboo quartzite ranges)-- dynamic metamorphism of erosion of origin of submergence of thickness of uplift of rapids rejuvenation of streams ripple marks , roches moutonnée sandstone (see potsdam and st. peters). sauk prarie , , skillett creek , , slope of upper surface of ice snow fields soil , , stand rock steamboat rock st. peter's sandstone stratified drift - , streams, changes in subaqueous overwash plains subglacial till (ground moraines) sugar bowl talus slopes terminal moraines-- across the united states development of in devil's lake region boundaries of location of , , on the main quartzite range width of topography of till topography-- effect of, on ice movement erosion topography of drift-covered country , of driftless area , , , of plain surrounding quartzite ridge of quartzite ridges transportation by streams tributary valleys turk's head unconformity underground water unglaciated areas , , unstratified drift , , upper narrows , , , , valley, the-- beginning of characteristics of, at various stages - course of how a valley gets a stream limits of valley trains waterfalls weathering webster's prarie wisconsin lake wisconsin river witch's gulch transcriber's note: minor typographical errors have been corrected without note. irregularities and inconsistencies in the text have been retained as printed. words printed in italics are noted with underscores: _italics_. notes on the fenland by t. mckenny hughes, m.a., f.r.s., f.g.s., f.s.a. woodwardian professor of geology with a description of the shippea man by alexander macalister, m.a., f.r.s., m.d., sc.d. professor of anatomy cambridge: at the university press cambridge university press c. f. clay, manager london: fetter lane, e.c. edinburgh: princes street new york: g. p. putnam's sons bombay, calcutta and madras: macmillan and co., ltd. toronto: j. m. dent and sons, ltd. tokyo: the maruzen-kabushiki-kaisha _all rights reserved_ contents page geography of the fenland subsidence of the valley of the cam turbiferous and areniferous series absence of elephant and rhinoceros in turbiferous series absence of peat in areniferous series fen beds not all peat sections in alluvium peat; trees etc.: tarn and hill peat; spongy peat and floating islands; bog-oak and bog-iron marl: shell marl and precipitated marl the wash: cockle beds (heacham): buttery clay (littleport) littleport district buttery clay the age of the fen beds palaeontology of fens birds man description of the shippea man by prof. a. macalister geography of the fenland. the fenland is a buried basin behind a breached barrier. it is the "drowned" lower end of a valley system in which glacial, marine, estuarine, fluviatile, and subaerial deposits have gradually accumulated, while the area has been intermittently depressed until much of the fenland is now many feet below high water in the adjoining seas. the history of the denudation which produced the large geographical features upon which the character of the fenland depends needs no long discussion, as there are numerous other districts where different stages of the same action can be observed. in the weald for instance where the darent and the medway once ran off higher ground over the chalk to the north, cutting down their channels through what became the north downs, as the more rapidly denuded beds on the south of the barrier were being lowered. the character of the basin is less clear in this case because it is cut off by the sea on the east, but the cutting down of the gorges _pari passu_ with the denudation of the hinterland can be well seen. the thames near oxford began to run in its present course when the land was high enough to let the river flow eastward over the outcrops of oolitic limestones which, by the denudation of the clay lands on the west, by and by stood out as ridges through which the river still holds its course to the sea--the lowering of the clay lands on the west having to wait for the deepening of the gorges through the limestone ridges. a submergence which would allow the sea to ebb and flow through these widening gaps would produce conditions there similar to those of our fenlands. so also the witham and the till kept on lowering their basin in the lias and trias, while their united waters cut down the gorge near lincoln through a barrier now feet high. the basin of the humber gives us an example of a more advanced stage in the process. the river once found its way to the sea at a much higher level over the outcrops of jurassic and cretaceous rocks west of hull, cutting down and widening the opening, while the yorkshire ouse, with the aire, the calder and other tributaries, were levelling the new red sandstone plain and valleys west of the barrier and tapping more and more of the water from the uplands beyond. the equivalent of the wash is not seen behind the barrier in the estuary of the humber, but the tidal water runs far up the river and produces the fertile estuarine silt known as the warp. the fenland is only an example of a still further stage in this process. the great ouse and its tributaries kept on levelling the gault and kimmeridge and oxford clays at the back of the chalk barrier which once crossed the wash between hunstanton and skegness. the lowlands thus formed lie in the basin of the great ouse which includes the fenland, while the fenland includes more than the fens properly defined, so that things recorded as found in the fenland may be much older than the fen deposits. subsidence of the valley of the cam. during the slow denudation which resulted in the formation of this basin many things happened. there were intermittent and probably irregular movements of elevation and depression. glacial conditions supervened and passed away. the proof of this may be seen in the sections, figs. , and , pp. , and . at sutton bridge the alluvium has been proved to a depth of feet resting on boulder clay. at impington the boulder clay runs down to a depth of feet below the surface level of the alluvium. that means that this part of the valley was scooped out before the glacial deposits were dropped in it, and that the bottom of the ancient valley is now far below sea level. in front of jesus college, gravel with _elephas primigenius_ was excavated down to a depth of feet below the street, while in the paddocks behind trinity college the still more recent alluvium was proved to a depth of feet, i.e. feet below o.d. these facts indicate a comparatively recent subsidence along the valley, as no river could scoop out its bed below sea level. we need not for our present purpose stop to enquire whether this depression was confined to the line of the valley or was part of more widespread east anglian movements which are not so easy to detect on the higher ground. from the above-mentioned sections it is clear that the denudation, which resulted in the formation of the basin in the lowest hollow of which the fen beds lie, was a slow process begun and carried on long before glacial conditions prevailed and before the gravel terraces were formed. as soon as the sea began to ebb and flow through the opening in the barrier, the conditions were greatly altered and we see the results of the conflict between the mud-carrying upland waters and the beach-forming sea. turbiferous and areniferous series. the fen beds belong to the last stage and, notwithstanding their great local differences, seem all to belong to one continuous series. seeing then that their chief characteristic is that they commonly contain beds of peat it may be convenient to form a word from the late latin _turba_, turf or peat, and call them turbiferous to distinguish them from the areniferous series which consists almost entirely of sands and gravels. when the land had sunk so far that the velocity of the streams was checked over the widening estuary and on the other hand the tide and wind waves had more free access, some outfalls got choked and others opened; turbid water sometimes spread over the flats and left mud or was elsewhere filtered through rank plant growth so that it stood clear in meres and swamps, allowing the formation of peat unmixed with earthy sediment. banks are naturally formed along the margin of rivers by the settling down of sand and mud when the waters overflow, as seen on a large scale along the mississippi, the po, as well as along the humber and its tributaries. the effect of a break down of the banks is very different. a great hole is scooped out by the outrush, and the mud, sand and gravel deposited in a fanshape according to its degree of coarseness and specific gravity. a good example of this was seen in the disastrous mid-level flood at lynn in [ ] and the more recent outburst near denver in the winter of - [ ], of which accounts were published in contemporary newspapers. the varied accompanying phenomena can be well studied in the process of warping in yorkshire or the colmata in italy. [ ] _times_, _cambridge chronicle_, may , . [ ] _times_, jan. , . this was a much commoner catastrophe in old times, before the banks were artificially raised, and, as the streams could never get back into their old raised channel, this accounts for the network of ancient river beds which intersect the fens. the bottom of the turbiferous alluvium is always, as far as my experience goes, sharply defined. this of course cannot be seen in a borehole or very small section. the surface of the older deposits seems to have been often washed clean either by the encroaching sea or by the upland flood waters. in saying that there is an absence of sand and gravel in the fen beds we must be careful not to force this description too far. for when the first encroaching water was washing away any pre-existing superficial deposits the first material left as the base of the fen beds must have depended upon the character of the underlying strata, the velocity of the water and other circumstances. this is well seen in the whittlesea brickpit where an ancient gravel with marine shells rests on the oxford clay and over the gravel there creeps the base of the turbiferous series. it here consists chiefly of white marl which thins out to the left of the section and above becomes full of vegetable matter until it passes up into peat, over which there is a flood-water loam. about a mile west-north-west of little downham near ely, and within a couple of hundred yards of hythe, the fen beds were seen in a deep cut carried close to the gravel hill which here stretches out north into the fens. they consist at the base of material washed down from the spur of gravel and sand of the areniferous series against which the fen beds here abut. this basement bed is succeeded by beds of silt and peat of no great thickness as they are near the margin of the swamp. when any considerable thickness of the older areniferous gravels has been preserved, the base of the turbiferous series is smooth or only gently undulating. but where only small patches or pot-holes of gravel remain, there the top of the clay has been contorted and over-folded so as often to contain irregularly curved pipes and even isolated nests of sand and gravel[ ]. the base of the areniferous gravel must generally have been thrown down upon clay which had been clean cut to an even surface by denudation without any soaking of the surface or isolated heaps of gravel sinking into the clay under alternation of dry and wet conditions, such as would puddle the surface under the heaps and allow the masses of heavy gravel to sink in pipes and troughs. these small outlying patches of gravel are sometimes so little disturbed that we leave them in the areniferous, whereas they are sometimes so obviously rearranged that we must include them in the turbiferous series, taking care not to include derivative bones from the older in our list of fossils from the newer series. [ ] cf. _archaeol. journ._ vol. lxix, no. nd ser.; vol. xix, no. , pp. - . absence of elephant and rhinoceros in turbiferous series. the basement beds of the turbiferous or newer alluvial fen beds are clearly separated by their stratification from the areniferous or older alluvial terrace beds down the sloping margin of which they creep, but there is not anywhere, as far as i am aware, any passage or dovetailing of the fen beds into the gravel of the river terraces, while the difference in the fauna is very marked. it is however from such sections as those just described that the erroneous view arose that the elephant and rhinoceros occurred in the older fen beds. it is true that they have been found under peat in the fenland, but that is only where the gravel spurs of the old alluvial terraces or areniferous series have passed under the newer fen beds. i saw the remains of _rhinoceros tichorhinus_ in the gravel beds belonging to the older or areniferous series at little downham, and from the base of the gravel in the whittlesea brickpit i obtained a fine lower molar of _elephas antiquus_. this was, however, not in the gravel, but squeezed into the soft surface of the underlying jurassic clay. there have never been any remains of elephant or rhinoceros found in the turbiferous series. absence of peat in areniferous series. it is not easy to realise what the conditions were during the formation of the later terrace gravels (barnwell type), and, if it is a fact, why there was not then, as in later times, a marshy peat-bearing area here and there between the torrential deposits of the upper streams near the foot of the hills and the region where the tide met the upland waters. a few plants have been found in the barnwell gravel but they are very rare in this series. the older terrace gravel (barrington type) might be expected to furnish evidence of the existence of abundant vegetation if we are right in assigning it to about the age of the peaty deposits overlying the weybourn crag. but at present we have no evidence of any such deposit in the cambridge gravels. although there are great masses of vegetable matter formed in the swamps of tropical regions, peat is essentially a product of northern climes. pliny[ ] evidently refers to peat as used in friesland but not as a thing with which he was familiar. [ ] lib. xvi, cap. . fen beds not all peat. it must not, however, be imagined that the fen beds consist wholly or even chiefly of peat. as we travel north from cambridge the surface of the alluvium is brown earth for miles and only here and there shows the black surface of peat. the numerous ditches for draining the land confirm this observation, and when we have the opportunity of examining excavations carried down to great depths into the alluvium we usually find only a little peat on the surface or in thin beds alternating with silt and clay and marl. sometimes, but only sometimes, we have evidence of the growth of peat for a long time, then of the incoming of turbid water leaving beds of clay, then again of the tranquil growth of peat. all this points to changes of local conditions and shifting channels during a gradual sinking of the area, for some of the peat is below sea level. i believe that the volume of clay is much greater than that of peat, although from the common occurrence of peat on the surface and clay in the depth the area over which peat is seen is greater. we have not, however, the data for estimating the proportion of each. in embayed corners along the river even above cambridge we find little patches of peat, while on the other hand in deep excavations near the middle of the valley we find only thin streaks of peat or peaty silt. in the trial boreholes at the backs of the colleges there was only this kind of record of former swamp vegetation. sections in alluvium. in digging the foundations for the chimney of the electric lighting works opposite magdalene college the following section was seen (fig. , p. ). under the new tennis courts in park parade facing mid-summer common the section was somewhat different (fig. , p. ). while in the pit dug some years ago by mr bullock at the other end of the parade at the lower end of portugal place in the south-east corner of the common there was a section very similar to the last (fig. , p. ). +------ | made ground | | '- ' | +------ | black silt | | '- ' | +------ | ' peaty silt | +------ | ' gravel | +------ | gault | [illustration: fig. . section seen in foundations of chimney for electric lighting works near river opposite magdalene college, july, .] these three sections, immediately north of cambridge where the valley of the cam opens out on to the fens, are important as showing the variations right across the alluvium from side to side and the absence, here at any rate, of any indication of a constant sequence distinctly pointing to important geographical changes. a section seen under pembroke college boat house gave feet of clay and peaty silt on the black gravel which here, as in the borings at the backs of the colleges, forms the base of the alluvium. about half way down were bones of horse and stag, but i do not believe that these are of any great antiquity, probably not earlier than mediaeval. thickness depth +------ | irregular made ground | | clayey | | alluvium +------ | | peat | +------ | | | | | - | sand and gravel | | | | | +------ | +------ gravel | +------ | ' " | running sand | ' " +------ gault | _scale_ ' to " [illustration: fig. . section seen in digging foundations of tennis courts on midsummer common, cambridge.] lower down the river near ely a most important and interesting section has recently been exposed. a new bridge was built over the ouse near the railway station and to obtain material for easing the gradient up to the bridge a pit was sunk close to it on the east side of the river, and was carried down to the kimmeridge clay thus giving a clear section through the whole of the alluvium (fig. , p. ). depth | _a_ | | +------ ' | _b_ | +------ ' | _c_ | +------ ' _d_ | +------ ' " _e_ | +------ ' " | | | _f_ | | | | +------ ' " _g_ | +------ ' " _h_ | | _a._ dark clay, with much carbonaceous matter, scattered stones, and freshwater shells ' " _b._ tough clay ' " _c._ dark clay full of bits of wood ' " _d._ light coloured clay full of rootlets ' " _e._ rusty sand " _f._ false bedded gravel and sand pierced by rootlets ' " _g._ black silt and gravel ' " ------ _h._ gault ' " ====== [illustration: fig. . section seen in bullock's pit in s.e. corner of midsummer common.] it will be noticed that there is very little peat here and all of it was below o.d. the upper four feet of the clayey peat (_f_) looked as if the vegetable matter had been transported, perhaps from peat beds being destroyed by the river higher up, and been carried down in flood with the clay, while the lower four feet of peat (_h_) was only a cleaner sample of the same, before the river had cut down into the clay. the trees in both _f_ and _h_ were not trees that had grown on the spot and had been blown down, but were broken, water-worn, and evidently transported. _a_ +----------------- _b_ +----------------- _c_ +----------------- _d_ +----------------- _e_ +----------------- | _f_ |················· _g_ | +----------------- | _h_ | | +----------( )---- _i_ | +----------------- | _j_ | | +----------( )---- _a._ surface soil " _b._ clayey alluvium " _c._ peaty alluvium " _d._ brown clayey alluvium ' " _e._ peaty alluvium. " _f._ brown clayey peat with trees scattered throughout _g._ and lenticular beds of freshwater shells in it ' _h._ peat with trees to ' diam. ' _i._ mottled green and grey clay with lines of sand and gravel giving out water ' _j._ yellow clay with springs and much rusty water at bottom. ' ------ ' " ====== ( ) skull and a few other bones of horse. ( ) broken fragments of bone. _scale_ ' to " [illustration: fig. . section seen in pit dug for material for making up the roadway east of the new bridge over the ouse by the railway station. ely, .] if now we travel about miles a little west of north we shall arrive near the shore of the wash about half way across its southern coast line at sutton bridge. here i had an opportunity of seeing the material of which the alluvium is composed. with a view to securing a sound base for the foundation of the piers of the midland and great northern railway bridge an excavation was made through the whole of the fen beds down to the boulder clay which as i have already stated was reached at a depth of feet. the clerk of the works kindly gave me the following measurements (fig. ). depth thickness +---------- high water ( ' " above o.d.) | ' " | ' " +---------- ordnance datum ' " | silt and clay ' " +---------- {| {+---------- low water ( ' " below o.d.) {| {| ' "{| {| {| {+---------- bed of river ( ' " below o.d.) {| ' " +---------- | | | ' " | sand with shells | | | ' " +---------- ' " | loam and sand ' " +---------- | ' " | ballast with shells | ' " +---------- ' " | loam with peat ' " +---------- ' " | fine red ballast | mixed with clay ' " +---------- ' " | blue and grey clay | mixed with sand ' " +---------- ' " | ballast ' " +---------- | ' " | silty sand ' " +---------- | ballast with flint ' " | and stone ' " +---------- | | | stiff grey clay | | [illustration: fig. . section seen at sutton bridge.] here again we see that the only peat is a bed between three and four feet in thickness of mixed loam and peat more than feet below mean sea level. from these sections it is clear that along the direct and more permanent outfall from cambridge to the north, peat forms but a small part of the fen beds. peat is a substance of so much value as fuel, of such importance to the agriculturist, of such commercial value in what we may call its by-products, and of such scientific interest in the history of its formation and the remains which its antiseptic properties have preserved, that it has, as might be expected, a large literature of its own. i have before me a list of more than references to peat or to the fens. peat; trees and other plants; tarn peat and hill peat; bog-oak and bog-iron. when we turn aside into the areas cut off by spurs of gravel and islands of jurassic rock, we find wide and deep masses of peat which has grown and been preserved from denudation in these embayed and isolated areas. burwell fen, for instance, protected on the north and west by the cretaceous ridge of wicken and the jurassic ridge of upware, furnishes most of the peat used in the surrounding district. if we travel about two miles to the north-west from the pit dug near the railway station (see fig. , p. ) over the hill on which ely stands, we shall come to west fen, where there is a great mass of peat which has grown in a basin now almost quite surrounded by kimmeridge clay. in this there is a great quantity of timber at a small depth from the surface. the tree trunks almost all lie with their root-end to the south-west, but some are broken off, some are uprooted, telling clearly a story of growth on the peat which had increased and swelled till the surface was lifted above the level of floods. then some change--perhaps more rapid subsidence, perhaps changes in the outfalls--let in flood water, the roots rotted and a storm from the south-west, which was the most exposed side and the direction of the prevalent winds, laid them low. the frequent occurrence of large funguses, _hypoxylon_, _polyporus_, etc., points to conditions at times unfavourable to the healthy growth of timber. it is worth noting when trying to read the story of the fens as recorded by their fallen trees that in all forests we find now and then a few trees blown down together though the surrounding trees are left. this may be the result of a fierce eddy in the cycloidal path of the storm, but more commonly it seems to be due to the fact that every tree has its "play," like a fishing rod, and recurring gusts, not coinciding with its rhythm, sometimes catch it at a disadvantage and break or blow it down. the story told by the west fen trees is quite different from that told by the water-borne and water-worn trunks in the section by ely station. the same variable conditions prevailed also in the more westerly tracts of the fen basin, but the above examples are sufficient for our present purpose. from the large numbers of trees found in some localities and from records referring to parts of the fens as _forest_ it has sometimes been supposed that the fens were well wooded, but forest did not generally and does not now always mean a wood, as for example in the case of the deer forests of scotland. when ingulph[ ] says that portions of the fenland were disafforested by henry i, stephen, henry ii, and richard, who gave permission to build upon the marshes, this probably meant that they no longer preserved them so strictly, but allowed people to build on the gravel banks and islands in them. [ ] _history of croyland_, bohn's edition, p. . dugdale, recording a stricter enforcement of game-laws, quotes proceedings against certain persons in whittlesea, thorney and ramsey for having "wasted all the fen of kynges-delfe of the alders, hassacks and rushes so that the king's deer could not harbour there." he does not mention forest trees. in the growth and accidents of vegetation in a swamp there are some circumstances which are of importance to note with a view to the interpretation of the results observed in the fens. for instance in fine weather there is a constant lifting and floating of the confervoid algae which grow on the muddy bed of the stream. this is brought about by the development of gas under the sun's influence in the thick fibrous growth of the alga. the little bubbles give it a silvery gleam and by and by produce sufficient buoyancy in the mass to tear it out and make it rise to the surface dropping fine mud as it goes and thus making the water turbid. other plants, such as utricularia, duckweed, etc., have their period of flotation, and in the "breaking of the mere" in shropshire we have a similar phenomenon. in the "floating island" on derwentwater the same sort of thing is seen with coarser plants. all these processes are going on in the meres and in the streams which meander through the fens and did so more freely before their reclamation. but besides this, when the top of the spongy peat is raised above the water level and dries by evaporation, then heath, ferns and other plants and at last trees grow on it, until accident submerges it all again. this at once shows why we often find an upper peat with a different group of plant remains resting upon a lower peat with plants that grow under water. the most conspicuous examples of these various kinds of peat we see in the mountainous regions of the north and west, where the highest hills are often capped with peat from eight to ten feet in thickness, creeping over the brow and hanging on the steep mountain sides. sometimes, close by, we see the gradual growth of peat from the margin of a tarn where only water-weeds can flourish. the "hill peat" is made up of sphagnum and other mosses and of ferns and heather. the "tarn peat" of conferva, potamogeton, reeds, etc. as hill peat now grows on the heights and steeps where no water can stand and tarn peat in lakes and ponds lying in the hollows of the mountains and moors, so the changes in the outfalls and the swelling and sinking of the peat have given us in the fens, here the results of a dry surface with its heather and ferns and trees, and there products of water-weeds only, and, from the nature of the case, the subaerial growth is apt to be above the subaqueous. one explanation of the growth of peat under both of these two very different geographical conditions is probably the absence of earthworms. the work of the earthworm is to drag down and destroy decaying vegetable matter and to cast the mineral soil on to the surface, but earthworms cannot live in water or in waterlogged land, and where there are no earthworms the decaying vegetation accumulates in layer after layer upon the surface, modified only by newer growths. some years ago a great flood kept the land along the bin brook under water for several days and the earthworms were all killed, covering the paddock in front of st john's new buildings in such numbers that when they began to decompose it was quite disagreeable to walk that way. it reminded me of the effects of storm on the cocklebeds at the mouth of the medway, where the shells were washed out of the mud, the animals died on the shore and the empty shells were in time washed round the coast of sheppey to the sheltered corner at shellness. here they lie some ten feet deep and are dug to furnish the material for london pathways. in those cases when the storm had passed the earthworms and the cockles came again, but the hill peat is always full of water retained by the spongy sphagnum and similar plants, and the fens are or were continually, and in some places continuously, submerged and no earthworms could live under such conditions. the blackness of peat and of bog-oak may be largely but certainly not wholly due to carbonaceous matter. iron must play an important part. there is in the sedgwick museum part of the trunk of a sussex oak which had grown over some iron railings and extended some eight inches or more beyond the outside of the part which was originally driven in to hold the rails. mr kett came upon the buried iron when sawing up the tree in his works and kindly gave it to me. from the iron a deep black stain has travelled with the sap along the grain, as if the iron of the rail and the tannin of the oak had combined to produce an ink. the well-known occurrence of bog-iron in peat strengthens this suggestion. an opportunity of observing this enveloping growth of wood round iron railings is offered in front of no. , benet place, lensfield road. the trees in the fens often lie at a small depth and when exposed to surface changes perish by splitting along the medullary rays. it is not clear how long it takes to impart a peaty stain to bone, but we do find a difference between those which are undoubtedly very old and others which we have reason to believe may be more recent. compare the almost black bones of the beaver, for instance, with the light brown bones of the otter in the two mounted skeletons in the sedgwick museum. marl. "marl," as commonly used, is clay or carbonate of lime of a clayey texture or any mixture of these. beds of shell marl tell the same tale as the peat. shells do not accumulate to any extent in the bed of a river. they are pounded up and decomposed or rolled along and buried where mud or gravel finds a resting place. only sometimes, where things of small specific gravity are gathered in holes and embayed corners, a layer of freshwater shells may be seen. but to produce a bed of pure shell marl the quantity of dead shells must be very large and the amount of sediment carried over the area very small, while the margin of the pond or mere in which the formation of such a bed is possible must have an abundant growth of confervoid algae and other water plants to furnish sustenance for the molluscs. shell marl therefore suggests ponds and meres. of course it must be borne in mind that in a region of hard water, such as is yielded in springs all along the outcrop of the chalk, there is often a considerable precipitation of carbonate of lime, especially where such plants as chara help to collect it, as the callothrix and leptothrix help to throw down the geyserite. these beds of white marls, whether due to shells or to precipitation, are thus of great importance for our present enquiry as they throw light on the history of the fens. we should have few opportunities of examining the marl were it not for its value to the agriculturist. as it consists of clay and lime, it is not only a useful fertiliser but also helps to retain the dusty peat, which when dry and pulverised is easily blown away. moreover, as the marl occurs at a small depth and often over large areas, it can commonly be obtained by trenching on the ground where it is most wanted. the wash. we have now carried our examination of the fen beds up to the sea, but to understand this interesting area we must cross the sea bank and see what is happening in the wash. there is no peat being formed there, nor is there any quantity of drifted vegetable matter such as might form peat. there are marginal forest beds near hunstanton and holme, for instance, and it is not clear whether they point to submergence or to the former existence of sand dunes or shingle beaches sufficient to keep out the sea and allow the growth of trees below high water level behind the barrier, such as may be seen at braunton burrows, near westward ho, or at the mouth of the somme. what is the most conspicuous character of the wash is that the upland waters, now controlled as to their outlet, keep open the troughs and deeps while tidal action throws up a number of shifting banks of mud, sand and gravel, many of which are left dry at low water. along the quieter marginal portions fine sediment is laid down, and relaid when storms have disturbed the surface. on these cockles and other estuarine molluscs thrive. before the sea banks were constructed these tidal flats extended much further inland. littleport district. in the light of this evidence let us examine the fen beds east of littleport, a district of great interest not only from its geographical position in relation to the fens but also from the remains recently discovered there. looking north and west there is no high ground between us and the wash. if we could sweep out the soft superficial deposits and abolish the sea banks the tide would still ebb and flow over the whole area. if we look north and east we see the high ground stretching from downham market to stoke ferry and sweeping round to the south by methwold and feltwell and the islands of hilgay and southery, thus enclosing a great bay into which the wissey on the north and the brandon river on the south deliver the waters collected on the eastern chalk uplands. the island known as shippea hill marks the trend of an ancient barrier blocking the northward course of the river lark. (fig. , p. .) here, then, it seems probable that we might find evidence of a local change from the conditions we now see in the wash and those which have resulted in the formation of the fens. buttery clay. in deep trenching in the fen between littleport and shippea hill in order to obtain clay for laying on the peaty surface a very fine unctuous deposit was found at a depth of four or five feet. the overlying fen beds were chiefly peat with lenticular beds of white marl and grey clay, obviously laid down from time to time in small depressions in the surface of the peat. this marl was often largely made up of, or was at any rate full of, freshwater shells but sometimes showed evidence of having been gathered on the stems of chara which on perishing have left small cylindrical hollows penetrating the partly consolidated marl. under these beds of peat and marl there was the unctuous clay, which is sometimes referred to as the buttery clay. it is an estuarine deposit like that mentioned above as occurring in the wash off heacham, for instance. it contains shells of _cardium edule_, _tellina_ (_tacoma_) _balthica_, _scrobicularia piperata_, and other estuarine shells, some of which had the valves adherent or rather adjoining, for the ligament had perished. mrs luddington has in her collection the bones of the urus, wild boar and beaver, obtained from the peat above this buttery clay. on the other or south-western side of shippea hill, which is an island of kimmeridge clay, we get further into the embayed and isolated portions of the fen and we find more peat in proportion to the other deposits although it is very thin. there are still small lenticular beds of white marl similar to that nearer littleport and the peat rests upon buttery clay of unknown thickness. in this part, however, no shells have yet been noticed. near shippea hill the peat has recently been trenched with a view to obtaining clay with which to dress the surface of the peat and it was here, at a depth of four feet from the surface and four inches above the buttery clay, that the human bones described below (pp. - ) were found. the age of the fen beds. now we may enquire what are the limits within which we may speculate as to the age of the fen beds. these turbiferous deposits all belong to one stage, though it may be one of long duration. they are sharply separated from the areniferous deposits, i.e. the sands and gravels of the terraces and spurs which always pass under and, in fairly large sections, can always be clearly distinguished from the resorted layers at the base of the fen beds. there is no definite chronological succession which will hold throughout the fens. the variations observed are geographical--clay, marl, peat, etc., alternating in different order in different localities and subaerial, fluviatile, estuarine, and marine, having only a changing topographical significance. the fen beds crept over an area where the underlying formation had been undergoing vicissitudes due to slow geographical changes--changes which, being at sea level and near the conflict of tides and upland water, produced irregular but often important results. there is not in the fens any _continuous_ record of what took place between the age in which the little downham rhinoceros was buried in the gravel and that in which the neolithic hunters poleaxed the urus in the peat near burwell. palaeontology of fens. nor do we find any constant succession in the fauna and flora in the sections in the fens any more than we find a uniform distribution of plants and animals over the surface to-day. the most numerous and largest specimens of the urus i have obtained from near isleham: the best preserved beaver bones from burwell. modern changes of conditions have limited the district in which the fen fern (_thelypteris_) or the swallow-tailed butterfly may now be seen; but nature in old times produced as great changes in local conditions as those now due to human agency. when we compare the fauna of the areniferous series with that of the turbiferous, although there is not an entire sweeping away of the older vertebrate and invertebrate forms of life and an introduction of newer, there is a marked change in the whole facies. there is plenty of evidence about cambridge of the gradual extermination of species still going on. indeed, i feel inclined to say that there is no such thing as a holocene age. i remember land shells being common of which it is difficult now to find live specimens, and my wife[ ] has shown how the mollusca are being differentiated in isolated ponds left here and there along the ancient river courses above the town. [ ] "on the mollusca of the pleistocene gravels in the neighbourhood of cambridge," by mrs mckenny hughes. _geol. mag._ decade , vol. v, no. , may , p. . but we have not in older beds of the turbiferous or newer beds of the areniferous series any suggestion of continuity between the two. there must have been between them an unrepresented period of considerable duration in which very important changes were brought about. perhaps it was then that england became an island and unsuitable for most of the life of the areniferous age. not only have we in the turbiferous as compared with the areniferous series a change of facies but we have many "representative forms," a point to which that keen naturalist, edward forbes, always attached great importance. we have for instance in the fen beds the brown bear (_ursus arctos_) with his flat pig-like skull, instead of the grizzly (_ursus ferox_) of the gravels with his broad skull and _front bombé_. if we turn to the horned cattle we shall find a confirmation of the view that there was not an entire break between the turbiferous and areniferous fauna for the urus (_bos primigenius_) occurs in both. this species became extinct in britain in the turbiferous period and before the coming of the romans, for no trace of it seems to have been found with roman remains in this country; and indeed when we remember the numerous tribes, the dense population and high civilisation of the natives of britain in roman times it seems improbable that they can have tolerated such a formidable beast as this wild bull around their cultivated land. some confusion has arisen as to the description and the names of the urus and the bison. caesar, who was not a big game hunter and probably never saw either, has given under the name urus a description which evidently mixes up the characters of both. both existed on the continent down to quite recent times and the bison is still found in poland, but later writers also have evidently confounded them. for instance, the augsburg picture of the urus is correct, but herberstein's, which also is said to represent the urus, is obviously that of a bison. i have gone into this question more fully elsewhere[ ]. [ ] "the evolution of the british breeds of cattle," _journ. r. agric. soc._ vol. v, ser. , pp. - , . "on the more important breeds of cattle which have been recognised in the british isles in successive periods, and their relation to other archaeological and historical discoveries," _archaeologia_, vol. v, ser. , pp. - , . cf. also morse, e. w., "the ancestry of domesticated cattle," _twenty-seventh annual report of the bureau of animal industry_, , department of agriculture, u.s.a. the urus (_bos primigenius_) is common in the fen beds and is of special importance for our present enquiry, as there is in the sedgwick museum a skull of this species found in burwell fen with a neolithic flint implement sticking in it. the implement is thin, nearly parallel sided, rough dressed, except on the front edge which is ground, and it is made of the black south-country flint. it is very different in every respect from the thick bulging implements with curved outlines, which being made of the mottled grey north-country flint or of felstone or greenstone suggest importation from a different and probably more northerly source. this gives us a useful synchronism of peat, a neolithic implement of a special well-marked type, and the urus. the bison is the characteristic ox of the gravels and never occurs in the fen beds; while the urus, as i have pointed out above, occurs in both the turbiferous and areniferous deposits. _bos longifrons_ is the characteristic ox of the fen beds and never occurs in the gravels. it is the breed which the romans found here, and we dig up its bones almost wherever we find roman remains. i cannot adduce any satisfactory evidence that it was wild, that is to say more wild than the welsh cattle or ponies or sheep which roam freely over wide tracts of almost uninhabited country. this species, like the urus, has horns pointing forward, but the cattle introduced by the romans had upturned lyre-shaped horns, as in the modern italian, the chillingham or our typical uncrossed ayrshire breed, and soon we notice the effect of crossing the small native cattle (_bos longifrons_) with the larger roman breed. the horse appears to have lived continuously throughout pleistocene times down to the present day and to have been always used for food. unfortunately the skull of a horse is thin and fragile and therefore it has been difficult to obtain a series sufficiently complete to found any considerable generalisations upon it. the animal found in the peat and alluvium appears to have been a small sized, long faced pony. the appearances and reappearances of the different kinds of deer is a very interesting question, but it will be more easily treated when i come to speak of the gravels of east anglia. i will only point out now that neither of the deer with palmated antlers properly belongs to the turbiferous series. the great irish elk (_cervus megacerus_) has not been found in the fen beds. indeed it is not clear that in ireland it occurs in the peat. the most careful and trustworthy descriptions seem to show that its bones lie either in or on top of the clays on which the peat grew. the other and smaller deer with palmated antlers, namely, the fallow deer (_cervus dama_), were reintroduced, probably by the romans, and although some of them have got buried in the alluvium or newer peat in the course of the years or so that they have been hunted in royal warrens in east anglia, they cannot be regarded as indigenous or indicative of climate or other local conditions. remains of the red deer (_cervus elaphus_) and of the roe deer (_cervus capreolus_) are common in the fen beds; both occur in the gravels also; and both are still wild in the british isles. unlike the red deer, which lives on the open moorland, the roe deer lives in woods and forests. and this is an interesting fact in its bearing upon our inferences as to the character of the country before the reclamation of the fens and the destruction of the plateau forest. the open downs and the spurs and islands of the fenlands offered the red deer a congenial feeding ground, while the thickets on the edge of the upland forest and the bosky patches along the margins of the lowland swamps provided covert for the roe deer. sheep and goat are found in the peat and the alluvium, but it is not easy to tell the age of the bones. they do generally appear to be of that lighter brown colour which is characteristic of remains from newer peat as compared with the black bones which seem to belong to the older and more decomposed peat. the sheep is probably a late introduction and is never found in the terrace gravel (see _geol. mag._ decade , vol. x, no. , p. ). the wild boar (_sus scrofa_) is fairly common. it is remarkable that we get very few remains of wolf, although it is not much more than years since the last was killed. there is in the sedgwick museum one fairly complete skeleton, found a long time ago in burwell fen and i have recently obtained another from the same locality. there do not seem to be any obvious and constant characters by which we can distinguish a wolf from a dog, and britain was celebrated for its large and fierce dogs. the bones of the eskimo dogs are very wolf-like, but they are frequently crossed with wolf. perhaps the most interesting animal whose remains are found in the fens is the beaver. why do we not find here and there a beaver dam? perhaps it is because we have not been on the look-out for it, and the peat-cutters would not have seen anything remarkable in the occurrence of a quantity of timber anywhere in the fens. we must suppose that the peat which often contains whole forests of trees and even canoes would have preserved the timber of the beaver dam. it is an animal too which might have contributed largely towards the formation of the fens by holding up and diverting meandering streams. perhaps it did not make dams down in the fens, and the skeletons we find are those of stray individuals or of dead animals which have floated down from dams near trumpington or chesterford; very suitable places for them. we want more evidence about the fen beaver. i have heard that there are beavers in the danube which do not make dams, but among those introduced into this country in recent years the dam building instinct seems to have survived the change. the beavers on the marquis of bute's property in scotland cut down trees and built dams as did the beavers in sir edmund loder's park in sussex, and even in the zoological gardens they recently constructed a "lodge." we have not found the beaver in the gravels. part of the skull of a walrus was brought to us a long time ago and said to have been found in the peat. but it is a very suspicious case. it does not look like a bone that had been long entombed in peat, and we are not so far from the coast as to make it improbable that it was carried there by some sailor returning home from northern seas. bones of cetaceans are thrown up on the shore near hunstanton, and seals are still not uncommon in the wash, so that we need not attach much importance to the occurrence in marine silt of whale, grampus, porpoise, and such like. birds. we have paid much attention to the birds of the fens, partly because of the occurrence of some unexpected species, and also because of the absence, so far as our collection goes, of species of which we should expect to find large numbers. perhaps the most interesting are the remains of pelican (_p. crispus_ or _onocrotalus_)[ ]. of this we have two bones, not associated nor in the same state of preservation. the determination we have on the authority of alphonse milne edwards and professor alfred newton. one of the bones is that of a bird so young that it cannot have flown over but shows that it must have been hatched or carried here. [ ] _annales des sciences naturelles, zool._ ( ), vol. viii, pl. , pp. - . _ibis_, , pp. - , _proc. zool. soc._ , p. . _trans. norfolk and norwich naturalists soc._ vol. vii, pt. , . _geol. mag._ no. , n.s. dec. , vol. viii, no. , p. . of the crane (_grus cinerea_) we have a great number of bones but of the common heron not one. i have placed a recent skeleton of heron in the case to help us to look out for and determine any that may turn up. bones of the bittern (_botaurus_ or _ardea stellaris_) are quite common, as are those of the mute or tame swan (_cygnus olor_) as well as of the hooper or wild swan (_cygnus musicus_ or _ferus_). goose (_anser_) and duck (_anas_) are not so numerous as one might have expected. the grey goose (_anser ferus_) and the mallard (_anas boscas_) are the most common, but other species are found, as for instance _anas grecca_. we have also the red breasted merganser (_mergus serrator_), and the smew (_mergus albellus_), the razor bill (_alea tarda_), the woodcock (_scolopax rusticola_), the water hen (_gallinula chloropus_) and a few bones of a limicoline bird, most likely a lapwing. we have found the skull, but no more, of the white-tailed or sea eagle (_haliaetus albicilla_). the whole is a strangely small collection considering all the circumstances. we find in the fens of course everything of later date, down to the drowned animals of last winter's storm, or the stranded pike left when the flood went down. it is a curious fact and very like instinct at fault that in floods the pike wander into shallow water and linger in the hollows till too late to get back to the river, so that large numbers of them are found dead when the water has soaked in or evaporated. an old man told me that he well remembered when pike were more abundant they used to dig holes along the margin when the flood was rising and when it went down commonly found several fine pike in them. this explains why we so often find the bones of pike in the peat, but where did the pike get into a habit so little conducive to the survival of the species? although we notice at the present day a constant change in the mollusca, their general continuity throughout the long ages from pre-glacial times is a very remarkable fact. the presence of _corbicula fluminalis_ and _unio littoralis_ in the gravels characterized by the cold-climate group of mammals such as _rhinoceros tichorhinus_ and _elephas primigenius_, the absence of those shells from the deposits in which _rh. merckii_ and _e. antiquus_ are the representative forms, and their existence now only in more southern latitudes, as france, sicily or the nile, but not in our turbiferous series, lay before us a series of apparent inconsistencies not easy of explanation. man. every step in the line of enquiry we have been following, from whatever point of view we have regarded the evidence, has forced upon us the conclusion that a long interval elapsed between the areniferous and turbiferous series as seen in the fens; and yet, having regard to the geographical history of the area with which we commenced, we cannot but feel that the various deposits represent only episodes in a continuous slow development due to changes of level both here and further afield and the accidents incidental to denudation. but the particular deposits which we are examining happen to have been laid down near sea level where small changes produce great effects. we may feel assured that over the adjoining higher ground the changes would have been imperceptible when they were occurring and the results hardly noticeable. if the fen beds include nearly the whole of the neolithic stage the idea that glacial conditions then prevailed over the adjoining higher ground is quite untenable. so far everything has taught us that the fens occupy a well-defined position in the evolution of the geographical features of east anglia and also that the fauna is distinctive, and, having regard to the whole facies, quite different from that of the sands and gravels which occur at various levels all round and pass under the turbiferous series of the fens. we will now enquire what is the place of these deposits in the "hierarchy" based upon the remains of man and his handiwork. no palaeolithic remains have ever been found in the fen deposits. we must not infer from this that there is everywhere evidence of a similar break or long interval of time between the palaeolithic and neolithic ages. there are elsewhere remains of man and his handiwork which we must refer to later palaeolithic than anything found in the areniferous series just near the fen beds, and there are, not far off, remains of man's handiwork which appear to belong to the neolithic age, but to an earlier part of it than anything yet found in association with the fen beds. the newer palaeolithic remains referred to occur chiefly in caves and the older neolithic objects are for the most part transitional forms of implement found on the surface in various places around but outside the fens and in the great manufactures of implements at cissbury and grimes graves, in which we can study the embryology of neolithic implements and observe the development of forms suggested by those of palaeolithic age or by nature. the sequence and classification adopted in these groups, both those of later palaeolithic and those of earlier neolithic age, are confirmed by an examination of the contemporary fauna; the areniferous facies prevailing in the caves and the turbiferous facies characterising the pits and refuse-heaps of cissbury and grimes graves. it is interesting to note that these ancient flint workings, in which we find the best examples of transitional forms, have both of them some suggestion of remote age. the pits from which the flint was procured at cissbury are covered by the ramparts of an ancient british camp and the ground near grimes graves has yielded palaeolithic implements _in situ_ in small rain-wash hollows close by--as seen near "botany bay." palaeolithic man came into this area sometime after the uplift of east anglia out of the glacial sea and was here through the period of denudation and formation of river terraces which ensued and the age of depression which followed. but neolithic man belongs to the later part of that period of depression when the ends of some of the river gravels were again depressed below sea level and the valleys had scarcely sufficient fall for the rivers to flow freely to the sea. in the stagnant swamps and meres thus caused the fen deposits grew, and in this time the shippea man met his death mired in the watery peat of the then undrained fens. human bones have not been very often found in the fen, and when they do occur it is not always easy to say whether they really belong to the age of the peat in which they are found or may not be the remains of someone mired in the bog or drowned in one of the later filled up ditches. that they have long been buried in the peat is often obvious from the colour and condition of the bone. by the kindness of our friends mr and mrs luddington my wife and i received early information of the discovery of human bones in trenching on some of their property in the fen close to shippea hill near littleport and we were able to examine the section and get some of the bones out of the peat ourselves (fig. ). a deposit of about ' " of peat with small thin lenticular beds of shell marl here rested on lead colored alluvial clay. in the base of the peat about four inches above the buttery clay a human skeleton was found bunched up and crowded into a small space, less than two feet square, as if the body had settled down vertically. _b_ +-----+ / \ [greek: ph] --------------/ \-------------- _c_ ···_d_ / \ _d´_··· _c_ / \ + -----------/ _a_ \----------- _e_ / \ _e´_ ---------+-------------------+--------- _a._ kimmeridge clay forming shippea hill, on which monastic buildings in connection with ely cathedral formerly stood. _b._ patches of rusty flint gravel. _c._ peat with bones of beaver, boar, urus, etc. _d._ shell marl, occurring in lenticular beds of limited extent in the upper part of the peat, sometimes in one bed as at _d_ and sometimes in several distinct beds as at _d´_. _e._ "buttery clay"; full of cockleshells etc. at _e_, but at _e´_ containing only freshwater shells and pieces of wood. + position of skeleton. [greek: ph] dressed flint flake on surface. [illustration: fig. . diagram section across shippea hill.] some of the bones were broken and much decayed, while others, when carefully extracted, dried and helped out with a little thin glue, became very sound and showed by the surface markings that they had suffered only from the moisture and not from any wear in transport. the most interesting point about them is the protuberant brow, which, when first seen on the detached frontal bone, before the skull had been restored, suggested comparison with that of the neanderthal man. much greater importance was attached to that character when the neanderthal skull was found. when i announced the discovery of the shippea man the point on which i laid most stress was that, notwithstanding his protuberant brow, he could not possibly be of the _age_ of the deposits to which the neanderthal man was referred. i stated "my own conviction that the peat in which the shippea man was found cannot be older than neolithic times and may be much newer" and, believing that similar prominent brow ridges are not uncommon to-day, i suggested that he might be even as late as the time of the monks of ely who had a retreat on shippea hill. the best authorities who have seen the skull since it has been restored by mr c. e. gray, our skilful first attendant in the sedgwick museum, refer it to the bronze age which falls well within the limits which i assigned. this skull is unique among the few that i have obtained from the fens. dr duckworth has described[ ] most of these, and i subjoin a description of the shippea man by professor alexander macalister. [ ] duckworth and shore, _man_, no. , , pp. , . description of the shippea man by prof. a. macalister. "the calvaria is large, dark coloured and much broken. the base, facial bones and part of the left brow ridge and glabella are gone. the sutures are coarsely toothed and visible superficially although ankylosis has set in in the inner face. the bone is fairly thick ( · mm.), and on the inner face the pacchionian pits are large and deep on each side of the middle line especially in the bregmatic part of the frontal and the post-bregmatic part of the parietals. the superior longitudinal groove is deep but narrow, and, as far as the broken condition allows definite tracing, the cerebral convolution impressions are of the typical pattern. [illustration: fig. .] "the striking feature is the prominent brow ridge due to the large frontal sinus. the glabella was probably prominent and the margins on each side are large and rough and extend outwards to the supraorbital notches. the outer part of the supraorbital margin and the processus jugalis are thick, coarse and prominent (fig. ). "in norma verticalis the skull is ovoid-pentagonoid euryme-topic with conspicuous rounded parietal eminences, slight flattening at the obelion and a convex planum interparietale below it (fig. ). [illustration: fig. .] "in norma lateralis the brow ridges are conspicuous; above them is the sulcus transversus from which the frontal ascends with a fairly uniform curve to the bregma. the frontal sagittal arc above the ophryon measures mm. and its chord . behind the bregma the parietals along the front half of the sagittal suture have a fairly flat outline to the medio-parietal region, behind which the flattened obelion is continued downwards with a uniform slope to the middle of the planum interparietale whence it probably descended by a much steeper curve to the inion, which is lost. the parietal sagittal arc, including the region where there was probably a supra-lambdoid ossicle, was about mm. and its chord but the curve is not uniform. "in norma occipitalis the sagittal suture appears at the summit of a ridge whose parietal sides slope outwards forming with each other an angle of °, as far as the parietal eminences. from these the sides drop vertically down to the large mastoid processes. the intermastoid width at the tips of the processes is , but at the supramastoid crest is (fig. ). [illustration: fig. .] "in norma frontalis the conspicuous feature is the brow ridge. this gives a kind of superficial suggestion of a neanderthaloid shape, but the broad and well arched frontal dispels the illusory likeness. the jugal processes jut out giving a biorbital breadth of mm. while the least frontal width is and the bistephanic expands to . there is a slight median ridge on the frontal ascending from the ophryon, at first narrow but expanding at the bregma to mm. the surface of this elevated area is a little smoother than that of the bone on each side of it. "the other long bones are mostly broken at their extremities. the femora are strong and platymeric. the postero-lateral rounded edge, which bears on its hinder face the insertion of the gluteus maximus, taken in connexion with the projection of the thin medial margin of the shaft below the tuberculum colli inferior causes the upper end of the shaft to appear flattened. the index of platymeria is · . the femoral length cannot have been less than mm. the man was probably of middle stature, not a giant as was the gristhorpe man. the tibiæ are also broken at their ends, they are eurycnemic (index · ) with sharp sinuous shin and flat back, the length may have been between and mm. the humeri are also bones with strong muscular crests, and the ulnæ are smooth and long. the fibula was channelled. there is nothing in the bone-features which is inconsistent with the reference of the skull to the brachycephalic bronze age race. [illustration: fig. .] "in the following table are recorded the measurements of the different regions. the two crania which i have selected to compare with it are ( ) a round-barrow skull from near stonehenge (no. in our collection) and ( ) the gristhorpe skull, to both of which it bears a very strong family likeness. shippea stonehenge hill (no. ) gristhorpe maximal length maximal breadth auricular height biorbital width bistephanic width least frontal width biasterial auriculo-glabellar radius auriculo-ophryal radius auriculo-metopic radius auriculo-bregmatic radius auriculo-lambdoid radius length and breadth index · · · "the resemblance to the two round-barrow skulls of the bronze age is too great to be accidental, so we may regard this as a representative of that race, possibly at an earlier stage than the typical form of which the two selected specimens are examples (fig. ). "the mandible also resembles that of the gristhorpe skull in general shape of angle and prominence of chin. "the measurements are as appended: shippea stonehenge hill (no. ) gristhorpe condylo mental length -- gonio mental length -- bigoniac -- bicondylar -- chin height -- " cambridge: printed by john clay, m.a. at the university press british museum (natural history) cromwell road, london, s.w. * * * * * mineral department. * * * * * an introduction to the study of meteorites, with a list of the meteorites represented in the collection. by l. fletcher, m.a., f.r.s., keeper of minerals in the british museum; formerly fellow of university college and millard lecturer at trinity college, oxford. * * * * * tenth edition. * * * * * [_this guide-book can be obtained only at the museum; written applications should be addressed to "the director, natural history museum, cromwell road, london, s. w."_] printed by order of the trustees. . [_all rights reserved._] london: printed by william clowes and sons, limited, duke street, stamford street, s.e., and great windmill street, w. preface. in the accompanying list, the topographical arrangement has been continued for those meteorites of which the circumstances of the fall are without satisfactory record. this mode of arrangement brings near together fragments which have been found in the same district at different times; in some cases they belong to the same meteoritic fall. as the dates of discovery of the masses and the dates of recognition of meteoric origin, upon which other lists of meteorites are based, have been stated very differently in the publications of the principal museums, a reference in each instance to the best available report, and a brief extract from it, are given. even as regards the dates of fall of the remaining meteorites there has been much discrepancy in the various lists: every case in which the date here given has been found to differ from that recorded in any other list has been verified by reference to the published reports of the fall. for the convenience of collectors there has been added (page ) an alphabetical list of those meteorites of which specimens have been first acquired since the issue of the last list (january , ). l. fletcher. _may , ._ table of contents. page arrangement of the collection history of the collection an introduction to the study of meteorites list of the meteorites represented in the collection on may , :-- i. siderites or meteoric irons ii. siderolites iii. aerolites or meteoric stones list of recent additions list of british meteorites appendix to the list of the meteorites:-- a. native iron (of terrestrial origin) b. pseudo-meteorites list of the casts of meteorites index to the collection [illustration: plan of the mineral gallery] arrangement of the collection. by ascending the large staircase opposite to the grand entrance and turning to the right, the visitor will reach a corridor leading to the department of minerals. from the entrance of the gallery the large mass of meteoric iron, weighing three and a half tons, found about at cranbourne, near melbourne, australia, and presented to the museum in by mr. james bruce, can be seen in the pavilion at the opposite end of the gallery. the other meteorites will be found in the same room, the smaller specimens in the four central cases, and the larger on separate stands. the casts of meteorites are exhibited in the lower parts of the cases. the specimens referred to in the 'introduction to the study of meteorites' are in case , and are arranged, as far as is practicable, in the order of reference. the remaining specimens are classified as:-- siderites, consisting chiefly of metallic nickel-iron (panes a- d): siderolites, consisting chiefly of metallic nickel-iron and stony matter, both in large proportions (panes e, f): and aerolites, consisting chiefly of stony matter (panes g- o). at the beginning of each class are placed those meteorites of which the fall has been observed. the position of any meteorite in the cases may be found by reference to the index (p. ) and to the second column of the list of the collection (p. ). history of the collection. until nearly fifty years after the establishment of the british museum, meteorite collections nowhere existed, for the reports of the fall of stones from the sky were then treated as absurd, and the exhibition of such stones in a public museum would have been a matter for ridicule; a few stones, which had escaped destruction, were scattered about europe, and were in the possession of private individuals curious enough to preserve bodies concerning the fall of which upon our globe such reports had been given. hence it happened that in not more than four meteoric stones were in the british museum: three of them, _krakhut_, _wold cottage_ and _siena_, had been presented in - by sir joseph banks; the fourth was a stone of the _l'aigle_ fall, presented in by prof. biot, the distinguished physicist. a fragment of the mass met with by the traveller pallas had been presented by the academy of sciences of st. petersburg as early as ; this, and the fragments of _otumpa_ and _senegal river_, were long regarded by scientific men as specimens of "native iron," and of terrestrial origin. in the year , happily for the future development of the mineral collection, mr. charles konig (formerly könig) was appointed assistant-keeper, and six years later was promoted to the keepership of the then undivided natural history department; it thus came about that for thirty-eight years the senior officer of the natural history department of the museum was one who had an intense enthusiasm for minerals and made them his own special study. it was in mr. konig's time that parliament voted ( ) a special grant of nearly £ , for the purchase of the minerals which had belonged to the rt. hon. charles greville; with these passed into the possession of the trustees fragments of seven meteorites, including _tabor_, which had been acquired by mr. greville with the mineral cabinet of baron born. the increase of the natural history collections was such that in the botanical, and in the zoological, specimens were assigned to special departments, after which mr. konig, as keeper of "minerals (including fossils)," was left free to devote his attention to those parts of natural history to which he was more particularly attached. during mr. konig's keepership, though numerous and excellent mineral specimens were acquired, no great effort was made to render the meteorite collection itself complete; at his death in , falls were represented by specimens. the following had been presented:-- _stannern:_ by the imperial museum of vienna, in . _red river:_ by prof. a. bruce, in . _mooresfort:_ by mr. j. g. children, f.r.s., in , and by dr. blake, in . _adare:_ by dr. blake, in . the large _otumpa_ iron, and a piece of the _imilac_ siderolite: by sir woodbine parish, k.c.b., f.r.s., in and respectively. _bitburg:_ by mr. henry heuland, in . _krakhut:_ by mr. wm. marsden, in . _cold bokkeveld_ meteorite: by sir john herschel, bart., f.r.s., sir thos. maclear, f.r.s., and mr. e. charlesworth, in and . _zacatecas:_ by mr. t. parkinson, in . _akbarpur:_ by captain p. t. cautley, in . _braunau_ and _seeläsgen:_ by the royal society, in . after the death of mr. konig, mr. g. r. waterhouse, palæontologist, was appointed keeper of the composite department. it was natural that the palæontological side should then have its turn of special development, and in fact the palæontological collections, already important, increased from that time with great rapidity; the mineralogical side, however, had additions made to it, though not in the proportion allotted during the preceding years. during the keepership of mr. waterhouse ( - ), only specimens of two additional meteorites were added to the collection; one of them, _madoc_, was presented in by sir wm. e. logan, f.r.s.; also additional fragments of _imilac_ were presented by mr. w. bollaert in . in the year , a further division of the natural history collections took place; the mineralogical and the palæontological specimens being assigned to special departments, and the minerals placed in the keepership of prof. story-maskelyne. under him the mineral collection was rendered as complete as possible in all its branches; and it is owing entirely to the unflagging energy he displayed, both in the search for, and in the acquisition of the best obtainable specimens, that the mineral collection was brought to its present position of general excellence. perhaps the greatest relative advance was made in the improvement of the collection of meteorites. perceiving that only half of the falls represented at vienna were represented in the british museum, and that the difficulty of making a fairly complete collection of such bodies must increase enormously as time goes on, owing to the absorption of the specimens by public museums, mr. maskelyne immediately after his appointment tried to fill up the gaps. in the first place, the meteorite collections of dr. a. krantz, mr. r. p. greg, and mr. r. campbell, and many meteorites belonging to mr. w. nevill and prof. c. u. shepard, were acquired by purchase in - . during the interval ( - ), the whole or parts of many meteorites were presented to the museum:-- from great britain.--_perth:_ by mr. w. nevill. from russia.--_tula:_ by dr. j. auerbach of moscow. from india.--_bustee_, _dhurmsala_, _durala_ and _shalka:_ by the secretary of state for india. _assam_, _butsura_, _futtehpur_, _khiragurh_, _manegaum_, _mhow_, _moradabad_, _segowlie_ and _umballa:_ by the asiatic society of bengal. _nellore_ and _parnallee:_ by sir w. t. denison, k.c.b. _kusiali_ and _pegu:_ by dr. thos. oldham, f.r.s. _kaee:_ by sir thos. maclear, f.r.s. _dhurmsala:_ by mr. g. lennox conyngham. from australia.--the large _cranbourne_ iron: by mr. james bruce. from south america.--_vaca muerta:_ by mr. w. taylour thomson. _imilac:_ by mr. w. bollaert. an _atacama_ iron: by mr. lewis joel. from north america.--_tucson:_ by the town authorities of san francisco. during the same interval, exchanges were made with the museums of paris, vienna, berlin, copenhagen, heidelberg, and göttingen, through professors daubrée, haidinger, rose, hoff, bunsen, and wöhler, respectively: and also with the following private collectors:--dr. abich of dorpat, dr. j. auerbach of moscow, mr. r. p. greg of manchester, prof. c. u. shepard of new haven, u.s.a., and dr. sismonda of turin. the result was that by the end of the number of meteoric falls represented in the collection was , and thus had been almost trebled during mr. maskelyne's first six years of office. meanwhile, although mr. maskelyne, with the help of a single assistant (mr. thomas davies), was then rearranging the general collection of minerals according to a new system of classification, time was found for a scientific examination of the meteorites thus being acquired. at that time the department was without a chemical laboratory, and not even a blowpipe could be used, owing to the necessity of guarding against a possible destruction of the museum by fire. hence recourse was had to the microscope, and as early as , a microscope fitted with a revolving graduated stage and an eye-piece goniometer was constructed, under the keeper's directions, for the examination of thin sections of meteorites with the aid of polarised light. working in this way, and with the simplest chemical tests, mr. maskelyne was the first to announce in the discovery in the bustee meteorite of a mineral, unknown in terrestrial mineralogy, to which he gave the name of oldhamite, and in , the more than probable occurrence of enstatite as an important meteoritic ingredient (nellore). this method of determining the mineral constituents of a rock-section by means of the relation of the vibration-traces to known crystallographic lines, thus first and of necessity employed for the discrimination of the minerals in meteorites, is now in general use in the investigation, not only of meteoritic, but of terrestrial rocks. about the same time, from the breitenbach meteorite were extracted crystals of bronzite, which yielded the first crystallographic elements obtained for that mineral: the measurements were made and published by dr. viktor von lang, then assistant in the department ( - ) and now professor of physics at vienna. the microscope was further applied to the mechanical separation of the different mineral ingredients of a meteorite: and by picking out in this toilsome manner the different mineral ingredients from the crumbled material of the bustee aerolite, and from the residue of the breitenbach siderolite left after the iron had been removed by mercuric chloride, the several silicates contained in these meteorites were isolated for future analysis. from the particles of colourless mineral thus obtained from the breitenbach meteorite, one kind was selected in , of which the crystals presented a zone of orthosymmetry containing two optic axes, and yielded two similar cleavages in a zone perpendicular to the former. this ingredient was afterwards ( ) announced to consist wholly of silica, a substance which, before the isolation of this mineral, was only known to occur as quartz, when in crystals, and these belong to the hexagonal system: to the new mineral mr. maskelyne later assigned the name of asmanite. in was published by vom rath the discovery of a species of terrestrial silica, the crystals of which were regarded as belonging to the hexagonal system, though their angular elements were distinct from those of quartz: this mineral, named by him tridymite, has since been found ( ) to present optical and other characters inconsistent with true hexagonal symmetry, and is probably identical in its specific characters with the meteoritic asmanite. further, another mineral occurring as minute gold-yellow octahedra in the bustee meteorite was recognised as new to mineralogy, and termed osbornite. it was not till , when a laboratory was fitted up outside the museum precincts, that it became possible to make a complete chemical examination of these materials, which had been gradually prepared and carefully picked for analysis. in that year the late dr. walter flight was appointed to assist in the laboratory-work of the department, and afterwards gave valuable help in the chemical analysis of the above materials; the results were quite confirmatory of those already obtained by aid of the microscope and the simple tests. since the great increase made during the first six years of prof. maskelyne's keepership, the collection has continued to grow, though necessarily at a less rapid rate. of the specimens added after , the following have been presented:-- - : _manbhoom_, _muddoor_ and _pokhra:_ by dr. thos. oldham, f.r.s. : _agra:_ by mr. wm. nevill. : _atacama_ (stone): by mr. alfred lutschaunig. - : _jamkheir_, _lodran_, _shytal_, _supuhee_ and _udipi:_ by the secretary of state for india. : _nerft:_ by prof. grewingk. : _ski:_ by prof. kjerulf. - : _goalpara_, _gopalpur_, _khetri_, _moti-ka-nagla_, _pulsora_ and _sherghotty:_ by the trustees of the indian museum. calcutta. - : _knyahinya_ and _zsadány:_ by the hungarian academy of sciences. : _krähenberg:_ by dr. neumayer. : _searsmont:_ by dr. a. c. hamlin. : fragments of thirteen meteorites already represented: by mr. benj. bright. : _bethany_ (_wild_): by the trustees of the south african museum, capetown. : _amana:_ by dr. g. hinrichs. : _shingle springs:_ by mr. e. n. winslow. : _rowton:_ by the duke of cleveland. : _khairpur_ and _jhung:_ by mr. a. brandreth. : _verkhne-dnieprovsk:_ by prof. koulibini. : _cronstad:_ by mr. john sanderson. : _santa catharina:_ by prof. daubrée. : _imilac_, _mount hicks_ and _serrania de varas:_ by mr. george hicks. : _middlesbrough:_ by the directors of the north eastern railway. : _veramin:_ by the shah of persia. : _vaca muerta:_ by mr. f. a. eck. : _ogi:_ by naotaro nabeshima, formerly daimiô of ogi, japan. : _ivanpah:_ by mr. h. g. hanks. : _youndegin:_ by the rev. charles g. nicolay. _et seq_.: _ambapur nagla_, _bishunpur_, _bori_, _chandpur_, _dokáchi_, _donga kohrod_, _esnandes_, _gambat_, _heidelberg_, _kahangarai_, _kodaikanal_, _lalitpur_, _nagaria_, _nammianthal_, _nawalpali_, _pirthalla_, _sindhri_, _wessely_ and _wöhler's iron:_ by the director of the geological survey of india. : _lucky-hill:_ by the governors of the jamaica institute. : _nenntmannsdorf:_ by dr. h. b. geinitz. : _jenny's creek:_ by mr. john n. tilden. : _djati-pengilon:_ by the government of the netherlands. , : _albuquerque:_ by dr. richard pearce. : _bhagur_ and _kalambi:_ by the bombay branch of the royal asiatic society. : _bendegó river:_ by the director of the national museum, rio de janeiro. : _dundrum:_ by the board of trinity college, dublin. : _farmington:_ by dr. g. f. kunz. - : _barratta_ and _thunda:_ by prof. a. liversidge, f.r.s. : _makariwa:_ by prof. g. h. f. ulrich. : _bherai:_ by the nawab of junagadh, india. : _concepcion:_ by mr. w. taylor. : _madrid:_ by don miguel merino of madrid. : _cold bokkeveld:_ by mrs. whitwell. , : _caperr:_ by the director of the la plata museum. : _el ranchito_ (bacubirito): by mr. o. h. howarth. : _kokstad:_ by the trustees of the south african museum. : _zomba:_ by sir a. sharpe, c.b., k.c.m.g., mr. j. f. cunningham, and mr. j. mcclounie. : _ness city:_ by dr. h. a. ward. : _caratash:_ by his highness kiamil pasha. : _narraburra:_ by mr. h. c. russell, c.m.g., f.r.s. : _fukutomi, oshima, tanakami and yon[=o]zu:_ by dr. c. ishikowa. : _kota-kota:_ by mr. a. j. swann. : _kangra:_ by prof. w. n. hartley, f.r.s. : _uwet:_ by the governor of southern nigeria. since the same year ( ) meteoritic exchanges have been made with the museums of belgrade, berlin, blömfontein, breslau, calcutta, calne, cambridge, chicago (field columbian museum), christiania, debreczin, dresden, fremantle, göttingen, helsingfors, munich, odessa, paris, pau, rio de janeiro, rome, st. petersburg (institute of mines), south africa, stockholm, sydney, transylvania, troyes, utrecht, vienna, washington, wisconsin university, and yale college; and also with the following:--dr. abich of dorpat, dr. j. auerbach of moscow, mr. s. c. h. bailey of cortlandt-on-hudson, u.s.a., prof. baumhauer of haarlem, mr. c. s. bement of philadelphia, u.s.a., dr. breithaupt of freiberg, dr. a. brezina of vienna, mr. j. b. gregory of london, prof. c. t. jackson of boston, u.s.a., mr. henry ludlam of london, prof. w. mallet of virginia, u.s.a., prof. vom rath of bonn, prof. c. u. shepard of new haven, u.s.a., his excellency julien de siemachko of st. petersburg, prof. lawrence smith of louisville, u.s.a., mr. j. n. tilden of new york, u.s.a., and dr. henry a. ward of chicago, u.s.a. in this way, by the generosity and self-denial of donors, by the somewhat difficult method of exchange, and by purchase, it has been possible to get together the fine representative collection of meteorites now in the british museum. an introduction to the study of meteorites. * * * * * _most of the specimens here referred to are in case in the pavilion at the end of the mineral gallery._ * * * * * [sidenote: the fall of stones from the sky formerly discredited.] . till the beginning of the nineteenth century, the fall of stones from the sky was an event, the actuality of which neither men of science nor people in general could be brought to credit. yet such falls have been recorded from the earliest times, and the records have occasionally been received as authentic by a whole nation. in most cases, however, the witnesses of such an event have been treated with the disrespect usually shown to reporters of the extraordinary, and have been laughed at for their supposed delusions: this is less to be wondered at when we remember that the witnesses of the arrival of a stone from the sky have usually been few in number, unaccustomed to exact observation, frightened both by what they saw and by what they heard, and have had a common tendency towards exaggeration and superstition. [sidenote: ancient records.] . de guignes in his travels states that, according to old chinese manuscripts, falls of stones have again and again been observed in china; the earliest mentioned is one which happened about b.c. a stone, famous through long ages,[ ] fell in phrygia and was preserved there for many generations. about b.c. it was demanded from king attalus and taken with great ceremony to rome. it is described as "a black stone, in the figure of a cone, circular below and ending in an apex above." in his history of rome, livy tells of a shower of stones on the alban mount, about b.c., which so impressed the senate that a nine days' solemn festival was decreed; as the shower lasted for two days, it was doubtless the result of volcanic action; other instances of the "rain of stones" in italy, mentioned by the same author, had possibly a similar origin. plutarch relates the fall of a stone in thrace about b.c., during the time of pindar, and according to pliny, the stone was still preserved in his day, years afterwards. the latter records two other falls, one in asia minor, the other in macedonia. [sidenote: worship of meteoric stones.] . these falls from the sky, when credited at all, have been deemed prodigies or miracles, and the stones have been regarded as objects for reverence and worship. it has even been conjectured that the worship of such stones was the earliest form of idolatry. the phrygian stone, mentioned above, was worshipped at pessinus by the phrygians and ph[oe]nicians as cybele, "the mother of the gods," and its transference to rome followed the announcement by an oracle that possession of the stone would secure to the state a continual increase of prosperity. similarly, the diana of the ephesians, "which fell down from jupiter," and the image of venus at cyprus, appear to have been, not statues, but conical or pyramidal stones. a stone, of which the history goes back far beyond the seventh century, is still revered by the moslems as one of their holiest relics, and is preserved at mecca built into the northeastern corner of the kaaba. the late paul partsch,[ ] for many years keeper of minerals in the imperial museum of vienna, considered that the meteoric origin of the kaaba stone was sufficiently proved by descriptions which had been submitted to him. a stone which fell in japan in the year , [sidenote: pane c.] and was presented to the british museum in , had long been made an annual offering in a temple of ogi at one of the japanese religious festivals. it may be added that a stone which lately fell in india[ ] was decked with flowers, daily anointed with ghee (clarified butter), and subjected to frequent ceremonial worship and coatings of sandal-wood powder. the stone was placed on a terrace constructed for it at the place where it struck the ground, and a subscription was made for the erection of a shrine. [sidenote: the oldest undoubted meteoric stone still preserved.] [sidenote: pane c.] . the oldest undoubted sky-stone still preserved is that which was long suspended by a chain from the vault of the choir of the parish church of ensisheim in elsass, and is now kept in the rathhaus of that town. the following is a translated extract from a document which was preserved in the church:-- "on the th of november, , a singular miracle happened: for between and in the forenoon, with a loud crash of thunder and a prolonged noise heard afar off, there fell in the town of ensisheim a stone weighing pounds. it was seen by a child to strike the ground in a field near the canton called gisgaud, where it made a hole more than five feet deep. it was taken to the church as being a miraculous object. the noise was heard so distinctly at lucerne, villing, and many other places, that in each of them it was thought that some houses had fallen. king maximilian, who was then at ensisheim, had the stone carried to the castle: after breaking off two pieces, one for the duke sigismund of austria and the other for himself, he forbade further damage, and ordered the stone to be suspended in the parish church." [sidenote: scientific men begin to investigate the reports.] . three french academicians, one of whom was the afterwards renowned chemist lavoisier, presented to the academy in a report on the analysis of a stone said to have been seen to fall at lucé on september , . [sidenote: pane c.] as the identity of lightning with the electric spark had been recently established by franklin, they were in advance convinced that "thunder-stones" existed only in the imagination; and never dreaming of the existence of a "sky-stone" which had no relation to a "thunder-stone," they somewhat easily assured both themselves and the academy that there was nothing unusual in the mineralogical characters of the lucé specimen, their verdict being that the stone was an ordinary one which had been struck and altered by lightning. [sidenote: chladni argues that the bodies come from outer space.] . in the german philosopher chladni, famed for his researches into the laws of sound, brought together numerous accounts of the fall of bodies from the sky, and called the attention of the scientific world to the fact that several masses of iron, of which he specially considers two, had in all probability come from outer space to this planet.[ ] [sidenote: the pallas iron.] [sidenote: pane c.] one of them is the mass still known as the pallas or krasnojarsk iron.[ ] this irregular mass, weighing about lbs., of which the greater part is in the museum at st. petersburg, was met with at krasnojarsk by the traveller pallas in the year , and had been found in by a cossack on the surface of the highest part of a lofty mountain between krasnojarsk and abakansk in siberia, in the midst of a schistose district: it was regarded by the tartars as a "holy thing fallen from heaven." the interior is composed of a ductile iron, which, though brittle at a high temperature, can be forged either cold or at a moderate heat; its large sponge-like pores are filled with an amber-coloured olivine; the texture is uniform, and the olivine equally distributed; a vitreous varnish had preserved it from rust. the fragment in the case, weighing about lbs., was presented to the trustees in by the academy of sciences of st. petersburg. [sidenote: the otumpa iron.] [sidenote: separate stand.] a second specimen referred to is that which in don michael rubin de celis was sent by the viceroy of rio de la plata to investigate;[ ] it had been found by indians, searching for honey and wax, and trusting to rain for drink, projecting about a foot above the ground near a place called otumpa, in the gran chaco gualamba, south america, and was at first thought to be the outcrop of an iron vein. don rubin de celis estimated the weight of this mass of malleable iron at thirty thousand pounds, and reported that for a hundred leagues around there were neither iron mines nor mountains nor even the smallest stones, and that owing to the absence of water, there was not a single fixed habitation in the country. there were several smaller masses at the locality; one of them, weighing lbs., is shown on a separate stand in the pavilion: according to sir woodbine parish, who presented it to the museum in , it had been removed to buenos ayres at the beginning of the struggle for independence; it was a complimentary gift to sir woodbine on the occasion of his being sent by canning to acknowledge the independence of the state. a slice of this iron is shown in case c. [sidenote: pane c.] [sidenote: chladni's arguments.] . chladni argued that these masses could not have been formed in the wet way, for they had evidently been exposed to fire and slowly cooled: that the absence of scoriæ in the neighbourhood, the extremely hard and pitted crust, the ductility of the iron, and, in the case of the siberian mass, the regular distribution of the pores and olivine, precluded the idea that they could have been formed where found, whether by man, electricity, or an accidental conflagration: he was driven to conclude that they had been formed elsewhere, and projected thence to the places where they were discovered; and as no volcanoes had been known to eject masses of iron, and as, moreover, no volcanoes are met with in those regions, he held that the specimens referred to must have actually fallen from the sky. further, he sought to show that the flight of a heavy body through the sky is the direct cause of the luminous phenomenon known as a fire-ball. [sidenote: the fall of stones at siena, in tuscany.] [sidenote: pane c.] . about seven o'clock on the evening of june , , as if to direct attention to chladni's just published theory, there fell a shower of stones at siena, in tuscany. the event is described in the following letter, dated siena, july , , from the earl of bristol to sir william hamilton, k.b., f.r.s., at that time british envoy-extraordinary and plenipotentiary at the court of naples:--[ ] "in the midst of a most violent thunderstorm, about a dozen stones of various weights and dimensions fell at the feet of different persons, men, women and children. the stones are of a quality not found in any part of the siennese territory; they fell about hours after the enormous eruption of mount vesuvius: which circumstance leaves a choice of difficulties in the solution of this extraordinary phenomenon. either these stones have been generated in this igneous mass of clouds which produced such unusual thunder, or, which is equally incredible, they were thrown from vesuvius, at a distance of at least miles: judge, then, of its parabola. the philosophers here incline to the first solution. i wish much, sir, to know your sentiments. my first objection was to the fact itself, but of this there are so many eyewitnesses, it seems impossible to withstand their evidence." [sidenote: the fall of a stone near wold cottage, yorkshire.] [sidenote: pane b.] . soon afterwards there fell a stone in england itself. about three o'clock in the afternoon of december , , a labourer working near wold cottage, a few miles from scarborough, in yorkshire,[ ] was terrified to see a stone fall about ten yards from where he was standing. the stone, weighing lbs., was found to have gone through inches of soil and inches of solid chalk rock. no thunder, lightning, or luminous meteor accompanied the fall; but in the adjacent villages there was heard an explosion likened by the inhabitants to the firing of guns at sea, while in two of them the sounds were so distinct of something singular passing through the air towards wold cottage, that five or six people went to see if anything extraordinary had happened to the house or grounds. no stone presenting the same characters was known in the district. the stone is preserved in the museum collection. [sidenote: terrestrial origin still sought for.] . it seemed to be now impossible for any one to doubt the fall of stones from the sky, but the reluctance of scientific men to grant an extra-terrestrial origin to them is shown by the theories referred to in the above letter to sir william hamilton, and is rendered even more evident by the theory proposed in by edward king, who suggested that the stones had their origin in the condensation of a cloud of ashes, mixed with pyritical dust and numerous particles of iron, coming from some volcano. as the stones fell at siena out of a cloud coming from the north, while vesuvius is really to the south, he gravely suggested that in this case the cloud had been blown from the south past siena, and had then before its condensation into stone been brought back by a change of wind. as to the fall of a stone near wold cottage, he was not prepared either to believe or disbelieve the witnesses until the matter had been more closely examined; but in case the statements should prove worthy of credit, he points out the possibility of the necessary dust-cloud having come from mount hecla in iceland. [sidenote: the fall of stones near benares, in india.] [sidenote: pane c.] . later came a well-authenticated account of a more wonderful event still. at o'clock on the evening of december , , many stones fell at krakhut, miles from benares, in india; the sky was perfectly serene, not a cloud had been seen since december , and none was seen for many days after. according to the observations of several europeans, as well as natives, in different parts of the country, the fall of the stones was preceded by the appearance of a _ball of fire_, which lasted for only a few instants, and was followed by an explosion resembling thunder. [sidenote: examination of stones by howard.] . fragments of the stones of siena, wold cottage, and krakhut, as also of a stone said to have fallen on july , , at tabor, in bohemia, came into the hands of edward howard, and the comparative results of a chemical and mineralogical investigation (the latter by the count de bournon) of the stones from the above four places are given in a paper read before the royal society of london, on february , . howard concludes as follows:-- [sidenote: pane c.] "the mineralogical descriptions of the lucé stone by the french academicians, of the ensisheim stone by m. barthold, and of stones from the above four places (siena, wold cottage, krakhut and tabor) by the count de bournon, all exhibit a striking conformity of character common to each of them, and i doubt not but the similarity of component parts, especially of the malleable alloy, together with the near approach of the constituent proportions of the earth contained in each of the four stones, will establish very strong evidence in favour of the assertion that they have fallen on our globe. they have been found at places very remote from each other, and at periods also sufficiently distant. the mineralogists who have examined them agree that they have no resemblance to mineral substances properly so called, nor have they been described by mineralogical authors." [sidenote: could projectiles reach the earth from the moon?] . this paper aroused much interest in the scientific world, and, though chladni's view that such stones come from outer space was still not generally accepted in france, it was there deemed more worthy of consideration after poisson[ ] (following laplace) had shown that a body shot from the moon in the direction of the earth, with an initial velocity of feet a second, would not fall back upon the moon, but would actually, after a journey of sixty-four hours, reach the earth, upon which, neglecting the resistance of the air, it would fall with a velocity of about , feet a second. [sidenote: the fall of stones at l'aigle, in france.] [sidenote: pane c.] . whilst the minds of the scientific men of france were in this unsettled condition, there came a report that still another shower of stones had fallen, this time in their own country, and within easy reach of paris. to settle the matter finally, if possible, the physicist biot, member of the french academy, was directed by the minister of the interior to inquire into the event upon the spot. after a careful examination of the stones and a comparison of the statements of the villagers, biot[ ] was convinced that-- . on tuesday, april , , about p.m., there was a noise as of a violent _explosion_ in the neighbourhood of l'aigle, in the department of orne, followed by a rolling sound which lasted for five or six minutes: the noise was heard for a distance of miles round. . some moments before the explosion at l'aigle, a _fire-ball_ in quick motion was seen from several of the adjoining towns, though not from l'aigle itself. . there was absolutely no doubt that on the same day _many stones fell_ in the neighbourhood of l'aigle. biot estimated the number of the stones at two or three thousand; they fell within an ellipse of which the larger axis was · miles, and the smaller · miles; and this inequality might indicate not a single explosion but a series of them. with the exception of a few little clouds of ordinary character, the sky was quite clear. the exhaustive report of biot, and the completeness of his proofs, compelled the whole of the scientific world to recognise the fall of stones on the earth from outer space as an undoubted fact. * * * * * [sidenote: the times and places of fall are independent of terrestrial circumstances.] . since that date many falls have been observed, and the attendant phenomena have been carefully investigated. these observations teach us that _meteorites_, as they are now called, fall at all times of the day and night, and at all seasons of the year, while they favour no particular latitudes: also they are found to be quite independent of the weather, and in many cases have fallen when the sky has been perfectly clear; even where stones have fallen in what has been called a thunder-storm, we may reasonably suppose that in most cases the luminous phenomenon has been mistaken for a variety of lightning, and the loud noise for thunder. [sidenote: velocity of meteorites.] . from observations of the path and the time of flight of the luminous meteor, it is calculated that meteorites enter the earth's atmosphere with absolute velocities ranging from to miles a second: the velocity actually observed is that relative to a person at rest on the earth's surface; for the determination of the absolute velocity of the meteorite, the motion of the observer with the earth (about miles a second) must be allowed for. let us attempt to follow the course of a small compact body moving at such a rate. so long as the body is traversing "empty space," the only heat it receives is that sent direct from the sun and stars; in general, the meteorite will thus be probably very cold, and, owing to its small size and want of luminosity, it will be invisible to an observer on the earth's surface. after the meteorite enters the earth's atmosphere a very speedy change must take place. [sidenote: the resistance of the air.] assuming the law of resistance of the air for a planetary velocity to be the same as that deduced from experiments with artillery, the astronomer schiaparelli[ ] has shown that if a ball of inches diameter and - / lbs. weight enter the atmosphere with a velocity of - / miles a second, its velocity on arriving at a point where the barometric pressure is still only / th of that at the earth's surface will have been already reduced to - / miles a second. from this it is clear that the speed of the meteorite after the whole of the atmosphere has been traversed will be extremely small, and comparable with that of an ordinary falling body. from experiments made by professor a. s. herschel, it has been calculated that the velocity of the meteorite which fell at middlesbrough, in yorkshire, on march , , was, on striking the ground, only feet a second. from the depth of the hole ( to inches) made in stiff loam by the stone which fell at hvittis, in finland, on october , , it has been estimated by mr. borgström that the meteorite had a velocity of feet a second when it reached the earth. he further calculates that the stone would have acquired virtually the same velocity if it had been merely allowed to fall, from a position of rest, under the action of gravity, through an infinite atmosphere having the same density as at the earth's surface. in the case of the hessle fall, several stones fell on the ice, which was only a few inches thick, and rebounded without either breaking the ice or being broken themselves. [sidenote: transformation of the energy.] . further, schiaparelli pointed out that, in the case imagined by him, the energy already converted into heat would be sufficient to raise , pounds of water from freezing point to boiling point under the ordinary barometric pressure. the greater part of this heat is, no doubt, carried off by the air through which the meteorite passes; but still the wonder is, not that a meteorite is small on reaching the earth's surface, but that any of it is left to "tell the tale." [sidenote: the cloud, ball of fire and trail.] this sudden generation of heat will cause fusion, and even luminosity, of the outer material of the meteorite, and in some cases a combustion of some of its constituents: the products of the thermal and mechanical action sufficiently account for the _cloud_ from which the meteorite is generally seen to emerge as a ball of fire, and also for the visible trail often left behind. the ball of fire has often an apparent diameter larger even than that of the moon, and is sometimes too bright for the eye to gaze upon. [sidenote: the meteorite is only luminous in the first part of its flight through the air.] . owing to the quick reduction of speed, the luminosity will be a feature of the higher, not the lower, part of the course. the orgueil meteorite of may , , was so high when luminous that, notwithstanding its almost easterly motion, it was seen over a space of country ranging from the pyrenees to the north of paris, a distance of more than miles. [sidenote: the time of flight through the air is very brief.] . next we may remark that the time of flight in the earth's atmosphere will be very short, and reckoned only by seconds. even when the meteorite is wholly metallic, if we may judge from the time one end of a poker may be held in the hand whilst the other end is in the fire, the heat will not have had time to get far below the surface before the body will have reached the ground. [sidenote: pane d.] [sidenote: the crust.] as a matter of fact, meteorites are almost invariably found to be covered with a _crust_ or varnish, such as would be caused by strong heating, and its thinness shows the slight depth to which the heat has had time to penetrate; in the case of the stones, the greater part of the suddenly heated superficial material must chip off and be left behind at all parts of the track of the meteor. the aspect of the crust varies according to the mineral constitution of the meteorites: it is generally black, and in most cases dull, as in high possil, zsadány and orgueil, [sidenote: pane d.] but sometimes shiny, as in stannern, or partly dull and partly shiny, as in dyalpur; rarely, it is of a dark grey colour, as in mezö-madaras and some of the stones which fell in the neighbourhood of mocs. in the case of the pultusk meteorite of january , , several thousands of stones, [sidenote: panes efg.] varying from the size of a man's head to that of a small nut, were picked up, each covered with a crust: fifty-six of the stones of this fall are shown in the case. [sidenote: the crust.] . the crust is not of equal thickness at every point; for, the form of the meteorite being a result of oft-repeated fracture, the constantly changing surface must be very irregular, and its different parts must be heated to different temperatures and be exposed to different amounts of mechanical action. sometimes, owing to the motion of the meteorite through the air, the crust is so marked as to indicate the position of the meteorite in regard to its line of motion at a certain part of its course; and this relation is rendered more clear in some cases by evidence that melted material has been driven to the back of the moving mass. the nedagolla iron and the goalpara stone illustrate this peculiarity. [sidenote: pane h.] [sidenote: the pittings.] . further, the surface of a meteorite is generally covered with _pittings_, which have been compared in form to thumb-marks: stones from the supuhee, futtehpur, [sidenote: pane h.] and knyahinya falls present good examples of this character. it is remarkable that pittings bearing a close resemblance to those of meteorites have been observed on the large partially burned grains of gunpowder, which have been [sidenote: pane h.] picked up near the muzzle after the firing of the -ton and -ton guns at woolwich. the pitting of the gunpowder grains is attributed to unequal combustion, but that of meteorites seems to be due not so much to inequality of combustibility as to that of conductivity, fusibility and frangibility of the matter at the surface. [sidenote: fragmentary form of meteorites.] . as picked up, complete and covered with crust, meteorites are not spherical, nor have they any definite shape: in fact, they are always irregular angular fragments, such as would be obtained on breaking up a rock presenting no regularity of structure. [sidenote: pane h.] in the case of the butsura fall of may , ,[ ] fragments of the stone were picked up three or four miles apart, and, wonderful to say, it was possible to reconstruct with much certainty the portion of the meteorite to which they once belonged: a model of the reconstructed portion is shown in the case. two of the fragments, [sidenote: pane a.] in other respects fitting perfectly together, are even on the faces of the junction now coated with a black crust, showing that one disruption took place when the meteorite had a high velocity; two other fragments found some miles apart fitted perfectly, and were neither of them incrusted at the surface of fracture, thus indicating another disruption at a time when the velocity of the meteorite had been so far reduced that the material of the new faces was not blackened through the generation of heat. sometimes, as in the case of the meteorite of orgueil, the fragments reach the ground before the detonation is heard, proving that the fracture has taken place at a part of the course where the velocity of the meteorite was considerably greater than that of the sound-vibrations ( feet a second). [sidenote: the detonations.] . the sudden condensation of air in front of the meteorite, the consequent generation of heat and expansion of the outer shell, have been held to account not only for the _break-up_ of the meteorite into fragments, but partly also for the _crash like that of thunder_ which is a usual accompaniment of the fall. others have referred this noise solely to the sudden rush of air into the space traversed by the meteorite in the early part of the course. it has, however, now been discovered that the mere flight of a projectile through the air with a velocity exceeding that of sound ( feet a second) is itself sufficient to cause a loud detonation; neither explosion, like that of a bomb-shell, nor simple fracture of the meteorite by reason of pressure or sudden heat, is a necessary preliminary to the production of the loud noise. it is found, in fact, that when a projectile is fired with high initial velocity, say feet a second, an observer near the path of the projectile begins to distinguish two detonations as soon as his distance from the cannon reaches feet; the first of them, a sharp one, appears to come from that part of the projectile's path which is nearest to the observer, and travels with the velocity of the projectile; the later and duller one appears to come from the cannon itself, and travels with the velocity of sound. if the projectile is intercepted near the cannon, only a single detonation is heard by an observer in the same position as before, and it travels at the rate of feet a second. if the initial velocity of the projectile is less than that of sound, only a single detonation is heard, and it starts from the cannon. the rolling sound, which follows the detonation of a meteorite, is due, as in the case of thunder, to echoes from the ground and the clouds. the detonations due to the different members of a swarm of meteorites will combine to form a single detonation unless they are separated by perceptible intervals of time. [sidenote: the sounds heard after the loud detonations.] . after the detonation, sounds are generally heard which have been variously likened to the flapping of the wings of wild geese, the bellowing of oxen, turkish music, the roaring of a fire in a chimney, the noise of a carriage on the pavement, and the tearing of calico: these sounds are probably due to the whirling and oscillation of the fragments while traversing the air, with small velocity, near the observers, and correspond to the hiss or hum observed in the case of a projectile travelling with a velocity less than that of sound. * * * * * [sidenote: the chemical elements found in meteorites.] . as to the _kinds of elementary matter_[ ] of which meteorites are composed, about one-third, and those the most common, of the elements at present recognised as constituents of the earth's crust have been met with: no new elementary body has been discovered. the most frequent or plentiful in their occurrence are:-- aluminium calcium carbon iron magnesium nickel oxygen phosphorus silicon sulphur: while, less frequently or in smaller quantities, are found: antimony arsenic chlorine chromium cobalt copper hydrogen lithium manganese nitrogen potassium sodium strontium tin titanium vanadium. [sidenote: elements present only in minute quantity.] . in addition to the above, the existence of minute traces of several other elements has been announced; of these special mention may be made of gallium, gold, iridium, lead, platinum and silver. [sidenote: both simple and combined.] . most of the above elements are present in the combined state; the iron occurring chiefly in combination with nickel, and the phosphorus almost always combined with both nickel and iron. some of them are found also in their elementary condition: perhaps hydrogen and nitrogen; carbon, both as indistinctly crystallised diamond and as graphitic carbon, the latter being generally amorphous, but occasionally in cubic crystals (cliftonite); free phosphorus has been found in saline township; free sulphur has been observed in one of the carbonaceous meteorites, but may have been separated from the unstable sulphides since the entry into our atmosphere. [sidenote: some of the constituents are new to mineralogy.] [sidenote: pane k.] . of the constituents of meteorites, the following are by many mineralogists regarded as being at present unrepresented among the terrestrial minerals:-- _cliftonite_, a cubic form of graphitic carbon, _phosphorus_, _various alloys of nickel and iron_, _moissanite_, silicide of carbon, _cohenite_, carbide of iron and nickel; corresponding to cementite, carbide of iron, found in artificial iron, _schreibersite_, phosphide of iron and nickel, _troilite_, proto-sulphide of iron, _oldhamite_, sulphide of calcium, _osbornite_, oxy-sulphide of calcium and titanium or zirconium, _daubréelite_, sulphide of iron and chromium, _lawrencite_, protochloride of iron, _asmanite_, a species of silica, _maskelynite_, a singly refracting mineral with the composition of labradorite. _weinbergerite_, silicate intermediate in chemical composition between pyroxene and nepheline. [sidenote: nature of troilite, asmanite and maskelynite.] of the above, _troilite_ is perhaps identical with some varieties of terrestrial pyrrhotite: _asmanite_, the form of silica obtained in by prof. maskelyne from the breitenbach meteorite, was announced by him in to be optically biaxal, and thus to belong to a crystalline system different from the hexagonal to which both tridymite, then just announced by vom rath, and quartz had been assigned. later investigations of tridymite have shown that its optical characters and crystalline form are inconsistent with the hexagonal system of crystallisation, and it is not impossible that asmanite and tridymite may be specifically identical. it has been found that tridymite becomes optically uniaxal at a moderate temperature, and its general characters appear to be essentially identical with those of asmanite. according to one view, _maskelynite_ is the result of fusion of a plagioclastic felspar; according to another, it is an independent species chemically related to leucite. [sidenote: compounds identical with terrestrial minerals.] [sidenote: pane k.] . other compounds are present, corresponding to the following terrestrial minerals:-- olivine and forsterite, enstatite and bronzite, diopside and augite, anorthite, labradorite and oligoclase, leucite, magnetite and chromite, pyrites, pyrrhotite, breunnerite. further, from one of the lancé stones, chloride of sodium, and from the carbonaceous meteorites, sulphates of sodium, calcium and magnesium, have been extracted by means of water. in addition to the above, there are several compounds or mixtures of which the nature has not yet been satisfactorily ascertained. [sidenote: the rarity of quartz.] . quartz, the most common of terrestrial minerals, is absent from the stony meteorites; but in the undissolved residue of the toluca iron microscopic crystals have been found, some of which have important characters identical with those of quartz, while others resemble zircon. as mentioned above, free silica is present in the breitenbach meteorite as asmanite. [sidenote: the conditions under which these compounds can have been formed.] . as to the _conditions_[ ] under which such compounds can have been formed, we may assert that they must have been very different from those which at present obtain near the earth's surface: in fact, it is impossible to imagine that phosphorus, the metallic nickel-iron and the unstable sulphides can either have been formed, or have remained unaltered, under circumstances in which water and atmospheric air have played any prominent part. still, what little we do know of the inner part of our globe does not shut out the possibility of the existence of similar elementary and compound bodies at great depths below the surface. daubrée,[ ] after experiment, inclines to the belief that the iron is due, in many cases at least, to reduction from an olivine rich in diferrous silicates, and this view perhaps acquires some additional probability from the fact that hydrogen and carbonic oxide are given off when meteoric iron is heated: the existence, however, of such siderolites as that of krasnojarsk, which is rich both in metallic iron and in orthosilicate of iron and magnesium (olivine), and yet presents no traces of the intermediate metasilicate of iron and magnesium (bronzite), offers a weighty objection to the general application of this view. [sidenote: classification.] . meteorites may be conveniently arranged in three classes, which pass more or less gradually into each other: the first includes all those which consist mainly of iron, and have, therefore, been called by prof. maskelyne aero-siderites (_aer_, air, and _sideros_, iron), or, more shortly, _siderites;_ the second is formed by those which are composed chiefly of iron and stone, both in large proportion, and are called aero-siderolites, or, shortly, _siderolites;_ while those of the third class, being almost wholly of stone, are called _aerolites_ (_aer_, air, and _lithos_, stone). [sidenote: the siderites.] . in the siderites the iron generally varies from to per cent., and the nickel from to per cent.; in the santa catharina siderite (of which the meteoric origin is somewhat doubtful) , and in that of oktibbeha county , per cent. of nickel have been found: the nickel is alloyed with the iron, and several of the alloys have been distinguished by special names. owing to the presence of the nickel, meteoric iron is often so white on a fractured surface as to be mistaken for silver by its finder; it is also less liable to rust than ordinary iron is. troilite is frequently present as plates, veins or large nodules, sometimes surrounded by graphite; schreibersite is almost always found, and occasionally also daubréelite. [sidenote: evolution of gases on heating.] further, various chemists have proved that hydrogen, nitrogen, marsh gas, and the carbonic oxides are evolved when meteoric iron or stone is heated; in one case a trace of helium was detected. probably the gases were not present in the occluded state, but resulted from the decomposition or interaction of non-gaseous constituents during the experiments. [sidenote: figures produced by action of acids or bromine.] [sidenote: pane l.] . the want of homogeneity and the structure of meteoric iron are beautifully shown by the figures generally called into existence when a polished surface is exposed to the action of acids or bromine; they are due to the inequality of the action on thick or thin plates of various constituents, [sidenote: etched figures.] the plates being composed chiefly of two nickel-iron materials termed kamacite and tænite. a third nickel-iron material, filling up the spaces formed by the intersection of these plates of kamacite and tænite, is termed plessite; it is probably not an independent substance but an intergrowth of the first two kinds. in the agram iron, investigated by widmanstätten in , the plates are parallel to the faces of the regular octahedron; such figures are well shown by the exhibited slice of the toluca iron; different degrees of distinctness of such "widmanstätten" figures are illustrated by specimens of seneca river, zacatecas, charcas, burlington, jewell hill, [sidenote: pane l.] lagrange, victoria west, nelson county, and seeläsgen. the large otumpa specimen, mounted on a separate pedestal, furnishes a good example of the less distinct, and more or less damascene, appearance presented by the etched surface of some meteoric irons of octahedral structure. the braunau iron gives no "widmanstätten" figures, but has cleavages parallel to the faces of a cube; on etching it yields linear furrows which were found ( ) by neumann to have directions such as would result from twinning of the cube about an octahedral face; as illustrations of the "neumann lines," etched specimens of braunau and salt river are exhibited. [sidenote: pane l.] for meteoric irons of cubic structure the percentage of nickel is lower than or ; for those of octahedral structure it is higher than or , and the plates of kamacite are thinner, and the structure therefore finer, the higher the percentage of that metal. a considerable number of meteoric irons, however, show no crystalline structure at all, and have percentages of nickel both below and above ; it has been suggested that these masses have been metamorphosed, and that crystalline structure was once present, but has disappeared as a result of the meteorites having been heated, not merely superficially during their passage through the earth's atmosphere, but throughout their mass while travelling in outer space. [sidenote: cooling of fused mixtures and of solutions.] . though meteoric iron has been at some time, presumably, in a state of fusion, and its present structure is a result of the particular circumstances of the cooling of the liquid and afterwards solid material, attempts to produce such structures by the cooling of fused meteoric iron or artificial mixtures of nickel and iron have not yet been successful. it will be useful, therefore, to consider briefly some of the manifold changes which are found to take place during the passage of fused mixtures and of solutions to the solid state, and during the cooling of such solids to ordinary temperatures. if a fused mixture of antimony and bismuth is allowed to cool, the solid which first separates is neither pure antimony nor pure bismuth, but a material which has a percentage composition depending on, though not identical with, that of the original mixture. the temperature for the beginning of the solidification is different for different proportions of the two metals, and is intermediate between ° and °, the solidifying temperatures of antimony and bismuth, respectively; it approaches the latter more and more closely as the percentage of the bismuth is increased. the solid first separated is somewhat richer in antimony than the original mixture; the still fused part, therefore, is somewhat richer in bismuth than before, and does not begin to solidify till a lower temperature is reached; the temperature thus gradually falls, instead of remaining constant, during the solidification. in the cooling of such fused mixtures the changing composition of the part still fused has for effect a changing composition of the solid already separated; whence the slower the cooling of the fused material, the greater is the homogeneity of the final solid. [sidenote: eutectic mixtures.] a fused mixture of silver and copper behaves in a different way. when the percentage weight of the silver is , and that of the copper, therefore, is , solidification begins, not at a temperature between ° and °, the solidifying temperatures of silver and copper, respectively, but at a temperature below both, namely, °. the solid which first separates has the same percentage composition as the original mixture; the part still fused has thus itself the same percentage composition as before, and continues to solidify at the same temperature, and in the same way, until the solidification is complete. such a mixture, having a definite composition and a definite temperature of solidification, was for a time regarded as a definite chemical compound with a complex chemical formula, but on microscopic examination the resultant solid is found to be heterogeneous; minute particles of the silver and copper are seen to lie side by side, the particles being granular or lamellar in form according to the circumstances of the cooling. if the percentage of silver is different from , whether it be higher or lower, the solidification begins at a higher temperature than °; whence the mixture containing per cent. of silver has been conveniently termed _eutectic_ (i.e. very fusible); the term was suggested by prof. f. guthrie,[ ] to whom our knowledge of the existence of such mixtures is due. [sidenote: cooling of fused mixtures and of solutions.] . when the silver is in excess of per cent., the excess of silver gradually collects together and solidifies at various parts of the cooling fused mass; the still fused portion thus gradually becomes poorer in that metal, and the temperature, instead of remaining constant, gradually falls during the separation of the solid. at length the percentage of silver in the fused portion falls to per cent. and the temperature to °; the solid which now begins to form is no longer pure silver, but a material containing per cent. of that metal; and it continues to have the same percentage composition as the surrounding liquid, and the temperature of solid and liquid to be °, until the solidification is complete. the final solid thus consists of blebs of silver scattered through a fine groundmass of eutectic mixture of silver and copper. similarly, if the copper is in excess of per cent., the final solid consists of blebs of copper scattered through a fine groundmass of eutectic mixture of silver and copper. if the two metals are copper and antimony, instead of copper and silver, the results are more complicated; for the first two metals are capable of combining together to form a definite chemical compound represented by the formula cu{ }sb, and each of the metals forms a eutectic mixture with the latter. according to the percentage composition of the original mixture, the solid which first separates during cooling from fusion may be either copper or antimony or the compound cu{ }sb; the separation continuing, and the temperature falling, until the first eutectic proportion and its corresponding temperature are reached. [sidenote: cooling of solutions.] . analogous results are obtained during the cooling of solutions; for instance, during the cooling of a solution of sodium chloride (common salt) in water. a solution containing · per cent. of sodium chloride begins to solidify at - ° c.; the separating solid is not simple sodium chloride or simple ice, but has the same percentage composition as the original solution, and thus the temperature remains - ° until the whole material has become solid. on microscopic examination the solid is seen to be heterogeneous, and to consist of small particles of sodium chloride and ice lying side by side. if the percentage of sodium chloride is different from · , whether higher or lower, solidification begins before the temperature has fallen to - °. the characters of this particular solution are thus closely analogous to those of the eutectic mixtures described above. if the sodium chloride exceeds · per cent., the excess of sodium chloride begins to separate, and solidify, at various parts of the liquid, at a temperature higher than - °; it continues to separate, and the temperature to fall, until the proportion of sodium chloride in the residual liquid is reduced to · per cent. and the temperature to - °. afterwards the separating solid has the same composition as the residual liquid ( · per cent. of sodium chloride), and the temperature remains constant, until the residual liquid has been wholly transformed into a solid fine-grained mixture of sodium chloride and ice. the final solid thus consists of large particles of sodium chloride dispersed through a fine groundmass consisting of eutectic mixture of sodium chloride and ice. similarly, if the water is in excess of · per cent., the final solid consists of large particles of ice dispersed through a fine groundmass consisting of eutectic mixture of sodium chloride and ice. the results of the cooling of a solution of ferric chloride are still more complicated; for this substance enters into chemical combination with water, and in no fewer than four different proportions. the solid which first separates from the cooling solution may thus, according to the percentage of ferric chloride, be either ferric chloride or water, or any one of the various compounds of the two; and to each pair of compounds nearest to each other in composition corresponds a different eutectic mixture and a different temperature for its formation. [sidenote: cooling of solids.] . some solid bodies, during cooling, show changes analogous to those observed in solutions, and are therefore termed "solid solutions." for instance, if a hot physically homogeneous solid obtained from the fusion of iron with carbon is cooled, there may result a separation in the solid of particles of either iron or cementite, the latter being a chemical compound of iron and carbon represented by the formula fe{ }c; the particular substance separated depending on the percentage composition of the original solid. this separation continues, and the temperature falls, until the residual physically homogeneous material contains · per cent. of carbon and the temperature is °; the temperature then remains constant, although the body is surrounded by a cooling medium, until this residual physically homogeneous material has been wholly transformed into a fine-grained mixture of iron and cementite, containing · per cent. of carbon. this particular kind of mixture has been termed eutectic, though the transformation has taken place, not by solidification from fusion, but in a body which was already solid. prof. rinne has proposed for such cases the substitution of the term _eutropic_, thus avoiding the suggestion of fusion. the eutectic mixture of iron (or ferrite) and cementite is known as pearlite. [sidenote: overcooling.] . just as water may be cooled so quietly that it is still liquid at a temperature much below the normal freezing point, a mixture may be cooled in such a way as to pass much below the eutectic (or eutropic) point without the normal transformation taking place; it is then said to be overcooled. the equilibrium, however, is very unstable, and the transformation, once begun, takes place almost instantaneously throughout the whole mass. [sidenote: crystalline structure of artificial iron.] . a structure analogous to that shown by the widmanstätten figures, though on a finer scale, has been observed by prof. j. o. arnold and mr. a. mcwilliam[ ] in cast steel containing · per cent. of carbon; the plates of iron (or ferrite) in the cast steel correspond to the plates of kamacite in meteorites. further, it has been found that the plates in the cast steel disappear during the process of annealing; similarly, there are no widmanstätten figures, and the structure of the material is granular, near the outer surface of an unweathered meteoric iron; presumably as a result of the high temperature to which the outer part of the mass has been raised during the passage of the meteorite through the earth's atmosphere. [sidenote: structure of meteoric irons.] . at present it is generally imagined that kamacite and tænite are definite alloys, or perhaps solid solutions, of iron and nickel, the former being poor in nickel ( or per cent.) and the latter rich in that constituent ( to per cent.), that kamacite and tænite separate in succession from the molten mass or solid solution until the residual part is so rich in nickel that a eutectic (or eutropic) proportion is reached; the residual material then forms plessite, which, according to this view, is a eutectic (or eutropic) mixture of kamacite and tænite. but it is difficult to understand how the thin plates of tænite are deposited on the plates of kamacite, seeing that they contain more nickel than kamacite and plessite, and yet have an intermediate epoch of formation, prior to the epoch of formation of that tænite which is a constituent of the plessite; one suggestion is that the thin plates of tænite have been deposited on the plates of kamacite owing to the temperature having fallen well below the eutectic (or eutropic) point after the separation of the kamacite and before the eutectic transformation of the residual material has taken place. and prof. rinne[ ] himself is of opinion that the widmanstätten structure has been wholly developed in meteoric iron after the solidification of the mass; further, as the relations of the kamacite, tænite and plessite to the enclosed troilite indicate that the troilite was solid before the octahedral structure was developed, and as that mineral, under normal circumstances, solidifies at about °, he infers that the structure was developed below that temperature. in the case of the jewell (duel) hill meteorite it was discovered by dr. brezina that, notwithstanding the pronounced octahedral structure, plates of troilite are embedded, not in accidental positions nor between successive octahedral layers, but parallel to the faces of the corresponding cube; whence prof. rinne suggests that this iron, now of octahedral structure, and possibly all others of a similar character, had a cubic structure at the epoch when they entered upon the solid condition. but, as both prof. rinne and dr. brezina[ ] have pointed out, a fused mixture of nickel and iron, cooling undisturbedly in outer space, may have solidified at a temperature even below ° and thus have been much overcooled. [sidenote: tænite possibly a eutectic mixture.] . in the course of a recent elaborate investigation of the changes of the magnetic permeability of the sacramento meteoric iron with changing temperature, mr. s. w. j. smith[ ] has been led to infer that the magnetic behaviour can only be explained by imagining the meteorite to consist largely of plates of nickel-iron, containing about per cent. of nickel (kamacite), separated from each other by thin plates of a nickel-iron constituent (tænite), containing about per cent. of nickel and having different thermo-magnetic characters from those of kamacite; he suggests, however, that tænite is not a definite chemical compound, but is itself a eutectic (or eutropic) mixture, and consists of kamacite and a nickel-iron compound containing not less than per cent. of nickel. and he points out that, while the tænite mechanically isolated from meteorites for analysis has approximately the lower percentage ( per cent.), the tænite chemically isolated through the prolonged action of dilute acid (which would remove much of the admixed kamacite) has a higher percentage, which in several cases approximates to per cent. [sidenote: few siderites have been seen to fall.] . the siderites _actually observed to fall_, or found soon after a luminous meteor had been seen, or a detonation heard, by people in the neighbourhood, reach only the small number of nine; they are, agram, charlotte, braunau, victoria west, nedagolla, rowton, mazapil, cabin creek, and n'goureyma. the remaining specimens in collections of siderites are presumed to be of meteoric origin by reason of the peculiarity of their appearance and chemical composition, and of the characters of the material in which they have been found (art. ). [sidenote: siderites of large size.] the large cranbourne meteorite, mounted in a special case in the pavilion, before rusting weighed - / tons. the two largest known were found in western greenland and mexico, respectively, and are both of very irregular shape. the greenland mass is feet long, - / feet wide, and feet thick, and its weight, which had been variously estimated at from to tons, has been determined to be - / tons; the mass had long been known to the eskimos, and was inquired after by captain john ross in ; it was shown by a native to lieutenant peary in , who afterwards transported it from melville bay to new york; it is now preserved in the american museum of natural history in that city. the mexican mass is feet long, feet wide, and feet thick, and has an estimated weight of tons; it is the property of the mexican government, and is still lying at el ranchito, near bacubirito, province of sinaloa. [sidenote: the iron found at ovifak is probably of terrestrial origin.] . the difficulty of distinguishing an iron of terrestrial from one of meteoric origin was rendered very evident by the prolonged controversy as to the origin of the large masses of iron, containing one or two per cent. of nickel, and weighing , , , , and , lbs., respectively, found in by baron n. a. e. nordenskiöld on the beach at ovifak, disko island, western greenland. a careful examination of the rocks of the neighbourhood shows that the basalt contains nickeliferous iron disseminated through it, and that the large masses of iron, [sidenote: pane m.] at first thought to be meteorites, are very probably of terrestrial origin, and have been left exposed upon the seashore through the weathering of the rock which originally enclosed them. some of the malleable metallic nodules extracted from the basalt were found to contain as much as · per cent. of nickel. in professor k. j. v. steenstrup[ ] found ferriferous basalt _in situ_ in three different parts of the island. at assuk (asuk) the enclosed balls of iron reach a diameter of nearly three-quarters of an inch. some assert that the basalt and the nickel-iron have been expelled together from great depths below the earth's surface, while others consider that the nickel-iron is due to the reduction of the iron-compounds in the basalt by the passage of the lava through the beds of lignite and other vegetable matter found in the vicinity. [sidenote: other terrestrial irons.] [sidenote: pane m.] . with the ovifak iron in the case are shown other specimens of iron which have been brought by various explorers from west greenland, and were formerly thought to have had a meteoric origin. the discovery of ferriferous basalt, not only _in situ_ in several places, but also deposited in a greenlander's grave ( ) along with knives (similar to those given to captain john ross in ) and the usual stone tools, renders it clear that the eskimos were not dependent solely on meteorites for their metallic iron, as had long been supposed. mr. skey announced in the discovery of terrestrial nickel-iron in new zealand. grains of the alloy (awaruite), containing as much as · per cent. of nickel, are found in the sand of the rivers flowing from a range of mountains composed of olivine-enstatite rocks, in places altered to serpentine: similar particles have been found in the serpentine itself. similarly, in the sand of the stream elvo, near biella, in piedmont, and of the river fraser, british columbia, grains of nickel-iron containing or per cent. of nickel have been found: and in the placer gravel of a stream in josephine and jackson counties, oregon, u.s.a., large quantities of waterworn pebbles, which enclose an alloy (josephinite) of nickel and iron containing per cent. of the former metal, have been met with. professor andrews many years ago established the presence of minute particles of metallic iron in some basalts; dr. sauer has lately found a single nodule of malleable iron of the size of a walnut in the basalt of ascherhübel, in saxony; dr. hornstein has described large nodules of (nickel-free) iron found in basalt in a quarry at weimar, near cassel; dr. beckenkamp has described nodules of metallic iron found in clay at dettelbach, near würzburg; and dr. johnston-lavis has announced the find of an enclosure of metallic iron in a leucitic lava of monte somma; dr. hoffmann has noted the occurrence of minute spherules of brittle iron both in perthite and quartzite in ontario; dr. hussak has recorded the discovery of metallic iron in an alluvium of brazil, and dr. högbom has found it associated with topaz, quartz, felspar, and other minerals, in limonite from an unspecified place in south america; two minute grains of iron were found by mr. osaka in the débris of an agglomerate at nishinotake, japan. [sidenote: the stony matter of meteorites.] . the stony part of the siderolites and aerolites is almost entirely crystalline, and in most cases presents a peculiar "chondritic" or granular structure, the loosely coherent grains being composed of minerals similar to those which enclose them, and containing in most cases minute particles of iron and troilite disseminated through them: glass-inclusions are found to be present. the minerals mentioned above as occurring in meteorites are such as are very characteristic of the more basic terrestrial rocks, such as dunite, lherzolite and basalt, which have been expelled from considerable depths below the earth's surface. . several attempts to classify aerolites according to their mineralogical constitution have been made, but it cannot be said that any of them is very satisfactory; seeing that even in the same stone there may be much difference in its parts, a perfect classification on such a basis is scarcely to be hoped for. [sidenote: chondritic aerolites.] about eleven out of every twelve of the stony meteorites belong to a division to which rose[ ] gave the name of _chondritic_ (_chondros_, a grain): they present a very fine-grained but crystalline matrix or paste, consisting of olivine and enstatite or bronzite, with more or less nickel-iron, troilite, chromite, augite and anorthic felspar; through this paste are disseminated round chondrules of various sizes (up to that of a walnut) and with the same mineral composition as the matrix; in some cases the chondrules consist wholly or in great part of glass.[ ] in mineral composition chondritic aerolites approximate more or less to terrestrial lherzolites. some meteorites consist almost solely of chondrules, others contain only few; in some cases the chondrules are easy separable from the surrounding material. of the chondritic division knyahinya, pegu, muddoor, [sidenote: pane n.] seres, judesegeri, khiragurh, utrecht and nellore (pane p) afford good illustrations. [sidenote: a carbonaceous group.] a few meteorites belonging to this division are remarkable as containing carbon in combination with hydrogen and oxygen. of these the alais and cold bokkeveld meteorites [sidenote: pane n.] are good examples: the former has a bituminous smell; it yields sulphates of magnesium, calcium, sodium and potassium, if steeped in water. [sidenote: aerolites without chondrules.] [sidenote: pane o.] . the remaining aerolites are not chondritic, and they contain little or no nickel-iron; of these we may specially mention for their mineral composition the following:-- _juvinas_ and _stannern_, consisting essentially of anorthite and augite. _petersburg_, consisting of anorthite, augite and olivine, with a little chromite and nickel-iron: both juvinas and petersburg may be compared to terrestrial basalt. _sherghotty_, consisting chiefly of augite and maskelynite. _angra dos reis_, consisting almost wholly of augite; olivine is present in small proportion. _bustee_, of diopside, enstatite and a little anorthic felspar, with some nickel-iron, oldhamite and osbornite. _bishopville_, of enstatite and anorthic felspar, with occasional augite, nickel-iron, troilite and chromite. _roda_, of olivine and bronzite. _chassigny_, consisting of olivine with enclosed chromite, and thus mineralogically similar to a terrestrial dunite. [sidenote: is there a periodic recurrence?] . the importance of the examination and classification of meteorites, with a view to a possible recognition of _periodicity_ of fall of specimens presenting the same characters, need only be mentioned to be appreciated: such a determination is, however, rendered very difficult by the close similarity of structure and composition presented by the great majority of the aerolites of the large chondritic division. [sidenote: few aerolites are known which have not been seen to fall.] . attention has been already directed to the fact that although many masses of meteoric iron, some of them like that of el ranchito, near bacubirito, in mexico, weighing very many tons, have been found at various parts of the earth's surface, very few of them have been actually observed to fall: in the case of the stony meteorites just the opposite holds good, for they are never very large, and few are known which have not an authenticated date of fall. this may be due to the fact that a meteoric stone is less easily distinguished than is a meteoric iron from ordinary terrestrial bodies, and will thus in most cases remain unnoticed unless its fall has been actually observed; while, further, a quick decomposition and disintegration must set in on exposure to atmospheric influences. the smaller size of the meteoric stones may be due to the greater ease with which they break up on the sudden increase of temperature of their outer surface, consequent on their entry into the earth's atmosphere. the largest meteoric stone preserved in a museum is one which fell as part of a shower at knyahinya, hungary, in : it weighs lbs. and is at vienna. a larger stone ( lbs.) fell at tabory, russia, in , but was broken to pieces by the impact on the earth; fragments of a still larger single stone, weighing at least lbs., were found near together at long island, kansas, u.s.a., but the fall was not observed. [sidenote: the chondrules and their matrix.] . if we now examine minutely the structure of the meteoric stones, it will be seen that almost all of them appear to be made up chiefly of irregular angular fragments, and that some of them bear a close resemblance to volcanic tuffs. in the large group of chondritic aerolites, chondrules or spherules, some of which can only be seen under the microscope while others reach the size of a walnut, are embedded in a matrix, apparently made up of minute splinters such as might result from the fracture of the chondrules themselves. in fact, until recently, it was thought by some[ ] that the chondrules owe their form, not to crystallisation, but to friction, and that the matrix was actually produced by the wearing down of the chondrules through collision with each other either as oscillating components of a comet or during repeated ejection from a volcanic vent of some small celestial body. chondrules have been observed, however, presenting forms and crystalline surfaces incompatible with such a mode of formation, and others have been described which exhibit features resulting from mutual interference during their growth. the crystallisation of the chondrules is independent of their form, and must have started, not at the centre, but at various places on their surfaces; dr. sorby[ ] argued that some at least of the chondrules must once have fallen as drops of fiery rain, and have assumed their shape in an atmosphere heated to nearly their own temperature. the chondritic structure is different from anything which has been observed in terrestrial rocks, and the chondrules are distinct in character from those observed in perlite and obsidian. after much study, dr. brezina[ ] lends his weighty support to the hypothesis that the structural features of meteorites are the result of a hurried crystallisation: and prof. wadsworth[ ] accepts the same interpretation. [sidenote: some meteoric materials appear to have been altered since their consolidation.] [sidenote: pane o.] . since the time of their consolidation some meteoric stones, as tadjera, appear to have been heated throughout their mass to a high temperature: and in the case of orvinio, chantonnay, juvinas, and weston, fragments are cemented together with a material having the same composition as the fragments themselves, thus giving rise to a structure resembling that of a volcanic breccia. others seem to have experienced a chemical change, for some of the chondrules in knyahinya and in mezö-madaras, when examined with the microscope, are found to be surrounded by spherical and concentric aggregations of minute particles of nickel-iron, perhaps due to the reducing action of hydrogen at a high temperature. others, as château-renard, pultusk and alessandria, present what in terrestrial rocks would probably be called faults: in some cases the fissures are seen to have been filled with a fused material after the chondrules have been broken and one side of the fissure has glided along the other. these peculiarities of structure suggest that the small body which reaches the earth is only a minute fragment of a much larger mass. it has been suggested that the chondritic structure is of metamorphic origin, and a mere result of enormous pressure on the stony material during the passage through the earth's atmosphere; according to still another view, the structure, though metamorphic, is of extra-terrestrial origin, and due to the quick cooling of a tuff-like stone which has been partially melted, for instance, by the heat from a neighbouring new star or by traversing the hot vapours on the limits of an old one. [sidenote: do meteorites reach our atmosphere as clouds of gas or dust?] . the idea that meteorites arrive at our own atmosphere, not as fragments of rock, but as mere clouds of gas or dust, has been recently revived and again discarded. according to this hypothesis, the air, instead of dispersing the entering cloud, acts in the contrary way, and in a few seconds of time presses the particles together to form solid bodies. this idea is open to various objections, and in any case one can scarcely understand how large masses of iron, presenting a wonderful regularity of crystalline structure, can have been the result of so hurried a process: and if we once grant that the irons enter the atmosphere as solid bodies, it is difficult to believe that the same is not the case with the stones. * * * * * [sidenote: where do meteorites come from?] . from the above it will be evident that the old hypotheses that meteorites are terrestrial stones which have been struck by lightning, or carried to the sky by a whirlwind, or are concretions in the atmosphere, or are due to the condensation of a dust-cloud coming from some volcano, or have been shot recently from terrestrial volcanoes, are inconsistent with later observation; it may be granted that the bodies reach our atmosphere from outer space. from what part or parts of space do they come? their general similarity of structure and chemical composition, and more especially the presence of nickeliferous iron in almost every one, suggest that most, if not all of them, have had a common source, and that they are chips of a single celestial body. [sidenote: probably not from the sun, nor from the moon, earth, or other planet.] . dr. sorby suggested that they are probably ejected from the sun itself, though this is difficult to reconcile with the fact that some of them are easily combustible. others, among whom we may mention laplace, have suggested that they come from volcanoes of the moon which are now active; but the suggestion, although mathematically sound, has no physical basis, for, so far as one can discover, active volcanoes do not there exist: and sir robert ball[ ] has virtually excluded the lunar volcanoes, which were active in times now long past, by pointing out that if a projectile from the moon once misses the earth, its chance of ever reaching the earth is too small to be worthy of mention. it has further been shown that, although the explosive force necessary to carry a projectile so far from one of the smaller planets that it will not return, is not very large, yet the initial velocity requisite to carry the body as far as the earth's orbit is so considerable, and the chance of hitting the earth so slight, that a more probable hypothesis is, to say the least, desirable. if these bodies have been shot from volcanoes of any planet, sir robert ball is himself inclined, upon mechanical grounds alone, to believe that the projection was from our own in bygone ages; for as such projectiles, having once got away from the earth, would take up paths round the sun which would intersect the earth's orbit, every one of them would have a chance of some time or other meeting with the earth again at the point of intersection, and of appearing as a meteorite. the size and initial velocity requisite for the escape of a projectile through a lofty atmosphere would be enormous: even then the difficulty would still remain that meteorites generally differ, both in structure and material, from anything known to have been ejected from existing terrestrial volcanoes. to meet these difficulties, sir robert has speculatively suggested that the matter was expelled before the surface of the earth became solid, and at a time when there was as much activity in the terrestrial planet as there is now in the material of the sun itself. nor is it probable that they are portions of a lost satellite of the earth, or are due to a collision of two planets; for in each of these cases we should expect to have received some of the larger fragments which must at the same time have been produced. much light is thrown on the history of meteorites by the discovery of a relationship with shooting stars and comets. [sidenote: shooting or falling stars.] . the meteorite-yielding fireball, referred to in art. , is not the only luminous meteor, apart from lightning, with which we are acquainted. on a clear dark night any one can see a star shoot now and then across the firmament: it is estimated that on the average as many as fourteen are visible to a single observer every hour. are the _shooting_, or, as they are often called, _falling stars_ products of our own atmosphere, or do they, like the meteorites, come from outer space? in chladni, in the memoir already referred to, gave reasons for believing that a meteoritic fireball and a shooting star are only varieties of one phenomenon. [sidenote: the november star-showers.] . but long after the cosmic origin of meteorites had been generally acknowledged, the atmospheric origin of the shooting stars was still asserted, and it was not till the wondrous star-shower of november - , ,[ ] that the cosmic origin of any of the shooting stars was finally established. during that night upwards of , shooting stars, according to a rough estimate, were seen from a single place; and the remarkable observation was made at various localities, widely distributed over north america, that the apparent paths of the shooting stars in the sky, when prolonged backwards, all passed through a point in the constellation leo: this point of radiation appeared to rotate with the heavens during the eight hours for which the shower was visible. hence it was manifest that the star-shower was independent of the earth's rotation and must therefore have come from outer space; that the radiation of the paths was only apparent and due to perspective; and that, relatively to an observer, the flights of all the shooting stars were really parallel to the direction of the apparent radiant point. on the same day of november in each of the three following years the shower was repeated though on a less grand scale, and the constancy of the radiant point was confirmed: similar small showers had been seen also in and before the radiation had been noticed. though in the years immediately before and after - no remarkable display of november meteors took place, it was remembered that a similar shower had been chronicled by humboldt and by ellicott, as observed by them on november , ; and a study of ancient documents revealed the fact that a grand star-shower had been recorded several times in october and november since a.d. , the date having gradually advanced, during that long space of time, from the middle of october to the middle of november.[ ] the only sufficient explanation of the observed facts is that a swarm of isolated small bodies, solid and non-luminous--meteorites in fact--is moving in an orbit round the sun, completing the circuit in - / years; the orbit intersects that of the earth, and the earth meets the swarm at the place of intersection. the isolated bodies or meteorites become luminous, as already explained in art. , after their entry into the earth's atmosphere. the swarm can be only a few hundred thousand miles thick, for the earth, travelling through space at the rate of , miles an hour, passes through the densest part in or hours, and through the whole in to hours: its length, however, must be enormous, amounting to hundreds of millions of miles; for, although the meteorites move with a velocity of twenty miles a second, the swarm takes or years to pass the place of intersection with the earth's orbit, thus causing star-showers, more or less dense, during that number of years. contrary to expectation, no large november star-shower occurred either in the year or in the years which have since elapsed. schiaparelli has shown that the unequal attraction of the sun for the individuals of a swarm of meteorites moving round it would scatter them along the orbit, and in the course of time produce a more or less complete ring; if this intersects the earth's orbit an annual star-shower must ensue. [sidenote: the august star-shower and its comet.] . a small annual star-shower occurs, in fact, on august - ,[ ] and has been observed since a.d. : it radiates from a point in the constellation perseus. schiaparelli calculated in the orbit and motion of the meteorites producing it, and was surprised to find that the numbers corresponded exactly with those calculated for one of the recently observed comets; in other words, a comet was moving in the path of the meteorites, and at exactly the same speed. at the same time schiaparelli gave numbers defining the motions of the meteorites which would cause the periodic november star-showers. [sidenote: star-showers related to comets.] . immediately afterwards, when the numbers calculated by oppolzer for the orbit of the comet discovered by tempel were published, it was seen that they were really identical with those already calculated by schiaparelli for the orbit of the meteorites of the november star-shower, and that here again a comet and a swarm of meteorites were moving in exactly the same path at exactly the same rate. almost immediately afterwards it was shown that the radiant points of the small star-showers of april - and november - both correspond to the orbits of known comets. it was evident that these could not be accidental coincidences, and that the comets and the attendant swarms of meteorites are closely related to each other. [sidenote: comets.] . an intimate connection between, if not complete identity of, meteorites, shooting stars and comets, had indeed long been suspected. astronomers were convinced that comets, though occasionally of enormous size, are always of extremely small mass, since they pass by the earth and other planets without sensibly disturbing their motions; the comet of passed through the system of jupiter's satellites without any perceptible action upon them: it has been calculated that the mass of a small comet may be about eight pounds. again, the light of a comet, like that of a cloud or planet, was seen to be partially polarised: hence part, at least, must be reflected sunlight, for the plane of polarisation passes through the sun's place. further, stars of very small magnitude have been seen not only through the tail, but even through the nucleus, of a comet without any apparent alteration of position by refraction: hence it was inferred that a comet is not a continuous mass, but consists of particles so far distant from each other that a ray of light may pass through the comet without meeting a single one of them. such a constitution likewise accounts for the absence of phases of the reflected light: for although only half of each particle will be directly illuminated by the sun, the remaining half will receive light irregularly reflected from the particles more distant from the sun. among others, chladni in had referred to the great similarity in the motions of comets and meteorites: olmsted, in , had calculated the orbit of a comet which would cause the november star-shower; his results were wrong owing to the assumption that the shower was annual: cappocci, in , gave reasons for believing that a meteorite is a small comet: reichenbach, in , in a most elaborate paper,[ ] sought to prove that a comet is a swarm of meteorites; that each chondrule of a meteorite had once been an individual of a cometary swarm, and owes its rounded shape to frequent collision with its fellows; that the rest of the stone consists of the broken splinters thus produced; and that the brecciated aspect of many meteorites is due to collisions in the denser part or nucleus of a comet. as already pointed out in art. , later modes of investigation have led petrologists to reject this method of accounting for the rotundity of the chondrules. [sidenote: other star-showers.] . in addition to the few radiant points which correspond to swarms moving in orbits identical with those of known comets, there are numerous radiant points which have not yet been recognised as related to existing comets, and may possibly be due to swarms produced by the dispersal of comets along their orbits; indeed, it has been inferred from observation of shooting stars that on the average there are no fewer than fifty distinct radiant points, and therefore showers, for any night of the year. but there are still others of which there is yet no satisfactory explanation. a cometary swarm is thin, and is passed through in a few hours; the stars are seen to radiate from the corresponding point of the sky for only that length of time: but there are other radiant points which have a duration of several months, and this is the case notwithstanding the constantly changing direction of the earth's motion in space.[ ] since the position of the radiant point in the sky as seen by a terrestrial observer depends not only on the direction in which the swarm is moving, but also on the velocity and direction of motion of the observer through space, it is easily seen that a radiant point having a fixed position during some months corresponds to something quite distinct from a cometary swarm. it has been suggested by mr. w. f. denning ( ) that in some cases a long-continued radiant point may really be due, not to a single swarm, but to successive swarms not physically associated with each other. on the other hand, professor h. h. turner has shown that the average effect of the earth's attraction on a meteorite passing near it is to change only the _position_ in our orbit at which we meet the meteorite (i.e. the time of year), not the relative-direction of motion or the relative speed; hence, a swarm of such meteorites must be spread out, in the course of ages, into a succession of rings, all of them equally inclined to the earth's orbit, but intersecting it at different places; the radiant point will then be of long duration. professor a. s. herschel[ ] made the suggestion that the radiant points of long duration may have resulted from the passage, in bygone epochs, of quickly moving streams of cosmical matter through a ring of small bodies circulating, as satellites, round the earth. [sidenote: daily and yearly maxima of shooting stars.] . the rotation of the earth round its axis is such that the part furthest from the sun, for which it is therefore midnight, is moving in the same direction as the earth in its orbit; whence, at the part of the earth most forward in the orbit it is sunrise, and at the part most backward it is sunset. thus, as schiaparelli pointed out, the meteorites which enter the atmosphere in the first half of the night are more or less following the earth in its orbit, and have their velocity relative to the earth diminished by the earth's own motion of translation; they are thus less likely to produce shooting stars than those which enter the atmosphere in the second half of the night and are travelling more or less oppositely to the earth as it moves in its orbit, and have their relative velocity increased. hence, if the directions of flight of meteorites were uniformly distributed in space, the number of shooting stars hourly visible at one place, a number which would be constant if the earth were at rest, would gradually vary during the night, reaching a maximum about a.m. also, as the point in space towards which the earth is moving in its orbit varies in height above the horizon during the year, being highest in autumn and lowest in spring, the number of shooting stars hourly visible at one place will gradually vary from night to night, reaching a maximum in the former season and a minimum in the latter, if the directions of flight of the meteorites be themselves uniformly distributed in space. [sidenote: the breaking up of comets.] . the history of biela's comet[ ] is of great interest as throwing light on the relationship of comets and swarms of meteorites. though already observed in and in , this comet was not recognised as periodic till it was seen by biela in , when its orbit was determined. on its returns in and it was found in its calculated positions, but in the latter year was seen to be double, a small comet being visible beside a larger one. vast changes took place during the time the companions were visible. the smaller one grew both in size and brightness, each threw out a tail, the smaller threw out a second tail, afterwards the larger showed two nuclei and two tails, then the smaller became the brighter of the two companions; next three tails were shown by the primary, and three cometary fragments were visible round its nucleus. on the next return, in , the two comets were farther apart, one being more than a million miles ahead of the other. the next favourable return was to be in , and the orbit was by this time so well known that the positions of the two companions could be calculated beforehand with great precision; owing to the changes which had been visibly taking place, the arrival of the comets was looked forward to with great interest by astronomers. but neither in , nor on the next occasion in , were they to be seen in their calculated positions, and a careful examination of the whole sky failed to lead to their discovery. the connexion between several comets and meteoritic swarms having in the meantime been established, it was now surmised that biela's comet might have been scattered along part of its path, and that some evidence of the dispersal might perhaps be obtained on the next occasion, november , , of the passage of the earth across the comet's orbit. in fact the star-shower of that date, with a radiant point corresponding to the orbit of biela's comet, was observed to be much more dense than usual, the stars shooting across the sky at the rate of a thousand an hour for several hours. [sidenote: passage of the earth through a comet.] . klinkerfues, a german astronomer, was struck with the idea that if this star-shower were really due to the passage of the earth through a moving swarm of meteorites, the latter might possibly be visible as it departed from our neighbourhood. the swarm having come from a radiant point in the northern sky, after passing the earth would need to be sought near the opposite point in the southern sky; he telegraphed, therefore, to the madras observatory, asking pogson, the astronomer, to search for the swarm in the direction opposite to the radiant point. the search was successful; on two mornings a small comet was distinctly seen, and on the second morning it showed a tail with an apparent length equal to one-fourth the apparent diameter of the moon. bad weather came on, and the comet got away without being again seen. the two madras observations agree with a motion in the orbit of biela's comet, and show that the earth had passed excentrically through the small comet seen by pogson. this small comet was probably a third fragment of biela's, for it was million miles behind the calculated position of the first two. from these two observations it is inferred that a swarm of meteorites, though only manifesting itself by a star-shower when passing through the earth's atmosphere, at some distance from us may be visible as a comet by reflected sunlight. [sidenote: fall of a meteorite during a star-shower.] . a dense star-shower[ ] recurred on the same day of the month (november ) in , the principal part being over in six hours. the hourly number visible at one place at the time of greatest density was estimated at , . in the densest part of the stream, the average distance of the individuals from each other was about twenty miles. during this star-shower a piece of iron weighing about lbs. was seen to fall at mazapil in mexico:[ ] in external characters and chemical composition it is similar to the other meteoric irons: the simultaneity was probably accidental. [sidenote: the reason of its rarity.] . it may be asked why, if star-showers are caused by the entry of solid bodies into our atmosphere from without, there is only one authentic instance of material being actually seen to fall and being picked up during such a shower. as it is absolutely beyond question that star-showers do come from outer space, we can seek an explanation only in the size or speed of the entering individuals, or in the nature of their material. a sufficient reason is to be found in the small size of the individuals; for the meteorites which actually reach the ground rarely weigh more than a few pounds, and are often quite minute; a small diminution of the original individual would thus ensure its complete destruction before the planetary velocity was exhausted: that the individuals of a swarm are extremely minute follows from the fact that the total mass of the biggest swarm is small, while the number of the individuals seems almost infinite. [sidenote: large and small luminous meteors essentially similar.] . between the small silent shooting star visible only with the telescope and the large detonating meteorite-yielding fireball there is every gradation; during the star-showers themselves many fireballs of great size and brilliancy are seen, while the smaller individuals appear in no way different from the solitary shooting star. the luminous meteors, large and small, are in the upper atmosphere, few higher than miles, few lower than miles from the earth's surface; they all have velocities of the same order of magnitude, comparable with that of the earth in its orbit; in each there must be a solid body, as is proved by the long path in the sky, for attendant gas or vapour would be immediately scattered or burnt; large and small present similar varieties of colour, and leave similar luminous trails; examination with the spectroscope teaches us that the light of the meteors is such as would result from the ignition of such meteorites as have actually reached the ground. the frequent absence of detonation may likewise be due in many cases to the small size, or small relative velocity, of the entering meteorite. [sidenote: the light of a comet.] . that part of the light of a comet is reflected sunlight is confirmed by examination with the spectroscope, in which instrument is seen a feeble continuous spectrum crossed by dark lines, identical with those afforded by the direct light of the sun. but a comet is also more or less self-luminous; for, in addition to the continuous spectrum, there are bright flutings and bright lines to which much attention has been given. the three ordinary bright flutings were found by sir william huggins in to be identical with the spectrum obtained when an electric spark is passed through olefiant gas, and they are now recognised as due to carbon. the carbon is presumed to be combined with hydrogen, sometimes also with nitrogen; in the case of comets approaching very near the sun, the lines of sodium, and others which have been supposed to be iron-lines, are seen.[ ] [sidenote: tait's suggestion.] . the discovery made by schiaparelli proves, as already pointed out, that there is a relationship between comets and meteoritic swarms; schiaparelli himself held the view that a comet and its attendant swarms are merely of identical origin. in [ ] tait discussed, from a purely dynamical point of view, the question as to whether the swarm of meteorites attending a comet may not really be part of the comet itself; he showed that many cometary characters can be mechanically explained on the assumption that comets are really swarms of small meteorites, and pointed out that the self-luminosity may be produced by the heating of the individuals through collision with each other. [sidenote: reproduction of the spectrum of a comet.] . flutings exactly identical with those seen in the spectrum of a comet were obtained by professor a. w. wright in [ ] on allowing the electric glow to pass through a heated tube, in which, after the introduction of fragments of the iowa meteorite, the gaseous density had been reduced by an air-pump. the bright lines, too, in the spectrum of a comet, even when nearest to the sun, are found by sir norman lockyer to be identical with those yielded when the electric glow is passed over ordinary meteorites at comparatively low temperatures; and further, the changes in these lines as the comet approaches and recedes from the sun are exactly those which take place on variation of the temperature of the meteorites enclosed in the glow-tubes. [sidenote: a comet is perhaps a swarm of meteorites.] . from these facts it is inferred that a comet may be in every instance a swarm of isolated large or minute meteorites, at a not very high temperature, shining partly by reflected sunlight and partly by the electric glowing of the gases evolved owing to the action of the sun's heat on the meteorites: further, some of the heat may be due to the clashing together of the meteorites, the grouping of which becomes more and more condensed as the swarm approaches the sun. the gases driven from the meteorites by the sun's heat would be quite sufficient in quantity to form the tail of the comet: as pointed out by professor wright, a meteorite like that which fell at cold bokkeveld would furnish cubic miles of gas measured at the pressure of our own atmosphere, and in space itself this gas would expand to enormous dimensions owing to the small mass and attraction of the meteoritic swarm. we are still uncertain, however, as regards the actual physical condition of the matter composing the tail of a comet. [sidenote: saturn's rings are probably swarms of meteorites.] . clerk-maxwell proved, as long ago as , that the stability of the rings which revolve round the planet saturn is inconsistent with their being formed of continuous solid or liquid matter; and has shown, by mechanical reasoning, that they must be revolving clouds of small separate bodies, like cannon-shot, each moving as a satellite and almost independent of the rest in its motion: determination of the motions of the inner and outer parts of the ring-system made with the help of the spectroscope supports this conclusion. [sidenote: nebulæ.] . reichenbach, in , before the self-luminosity had been proved by means of the spectroscope, had imagined a nebula to be a cloud of isolated meteorites, illuminated by some neighbouring sun: chladni, long before, had supposed a nebula to be a cloud of phosphorescent dust. but, in , it was established by sir william huggins that the light is due, not to reflection or phosphorescence, but to incandescence, for the spectrum consists of bright lines such as are yielded by glowing gas. tait,[ ] in , suggested that the nebulæ may be clouds of mutually impinging meteorites, mingled with glowing gases developed by the impacts; he pointed out that the heat produced by the clashing of the individuals of such an immense group as a nebula evidently is would be quite adequate for the production of their light. sir norman lockyer finds that the bright lines (generally accompanied by a certain amount of continuous spectrum) which have been observed in nebular spectra are consistent with this suggestion, and regards them as closely related to the low temperature lines obtained when a gentle electric glow is passed over meteorite-fragments in a tube containing gases given out by them, and of which the density has been reduced by the air-pump; further, he points out that the nebular spectrum is identical with that of the comets of and when distant from the sun. according to this suggestion, a nebula and a comet are of identical constitution, and a comet is merely a nebula which has become entangled in the solar system. on the other hand, sir william huggins has expressed ( ) the opinion that the spectrum of the bright-line nebulæ is certainly not such as we should expect to result from the collision of meteorites like those which have reached the earth, and that it is suggestive of a high temperature; he points out that the particles which have just been in collision may be at high temperatures and yet the average temperature of all the particles may be low. [sidenote: stars.] . the examination and classification of the spectra of the stars has likewise led to remarkable conclusions. secchi, following rutherfurd, found that the stars could be distributed into classes according to the characters of their spectra,[ ] and his classification has since, with little modification, been adopted by vogel and dunér, by whom several thousand star-spectra have now been systematically mapped. the first three classes are characterised by absorption, the fourth by radiation. in the spectra of class i the absorption is small and simple, the dark lines being broad and few; the stars themselves are white: in one division of this class, represented by sirius and vega, the principal lines are due to hydrogen; in another important division, represented by beta, gamma, delta, epsilon, zeta orionis, lines of helium are very pronounced. in class ii the dark lines are thinner and more numerous; the stars are bluish-white to reddish-yellow: to this class belong the sun, arcturus, capella. the absorption in class iii manifests itself predominantly as flutings, though there are also many thin lines: the stars are orange or red: in one division (a) of this class the darkest part and the sharpest edge of each fluting is towards the violet end of the spectrum, as in betelgeux; in a smaller division (b) the darkest part of each fluting is towards the red end, as in star schjellerup; the fluting absorption of the latter division being due to carbon. the remaining class iv is an extremely small one: the spectra are characterised by bright lines: some of the lines are due to hydrogen, and others to substances not yet recognised in terrestrial chemistry. [sidenote: supposed cooling of all the stars.] . soon after the classification suggested by secchi had been announced, it was surmised that the differences in the stars of the first three classes might be due, not so much to differences of matter, as to differences of temperature, and that a very hot star such as, from its brightness and distance, its small and simple absorption, and the development of the blue end of its spectrum, vega is believed to be, would, on getting older and colder, pass from class i to class ii, and thence to one or other of the divisions of class iii. [sidenote: new stars.] . in a star of th or th magnitude burst into greater brilliancy and nearly reached the intensity of vega; the spectrum showed the presence of brilliantly glowing hydrogen. almost as suddenly the light went down again, and within a month returned to its original brightness. ten years later, another new star of the rd or th magnitude appeared at a place in the sky where no star had been noticed before; its spectrum showed numerous bright lines; gradually, in the course of a year, it dwindled down to the th magnitude, then giving the telescopic appearance and the spectrum of a nebula. several other new stars have since been observed, the most notable being nova persei, which appeared in . in each case, as the star faded, its spectrum changed into that which is characteristic of the nebulæ. the appearance of a new star has been generally attributed to the collision of two bodies in space; sir norman lockyer[ ] has pointed out that the rapidity of the change in the brilliancy, so different from that of other stars, may be due to the smallness of the mass, and that such a star may be produced by the collision of two swarms of widely separated meteorites. he has shown that the changes in the spectrum as such a star varies in brightness are confirmatory of this view. [sidenote: the heat of the sun.] . that the heat of our own sun was originated by the falling together of smaller bodies was, until lately, generally acknowledged;[ ] for the only other conceivable natural cause, known to exist from independent evidence, namely, chemical combination, was quite insufficient; the greatest amount of heat obtainable from the most advantageous chemical combination of any of the then known elements, having a total mass equal to that of the sun, would not cover the sun's expenditure for more than three thousand years, while there is no difficulty on the meteoritic explanation in providing a supply of heat sufficient to cover the loss by radiation during , , years. but the discovery that compounds of radium maintain themselves at a higher temperature than that of surrounding bodies and are only inappreciably changed though continuously emitting an appreciable amount of heat, shows that the meteoritic hypothesis as to the cause of the sun's high temperature is not necessarily the true one: there may be an analogous heat-yielding material in the sun. in any case the present loss of the sun's heat by radiation is probably not covered by the fall of bodies into the sun; for the requisite mass would, if from distant regions, visibly affect the motions of the planets by its attraction, and, even if circulating round the sun at no great distance from it, would seriously disturb the motions of some of the comets. further, much heat will result from the shrinkage of the volume of the solar aggregate. [sidenote: evolution of the heavenly bodies.] . by study of the spectra, at various temperatures, of the elements and compounds found in those meteorites which have reached our earth and been preserved, sir norman lockyer[ ] has been led to support the view that the stars are not at present all cooling down, but that some, on the contrary, are rising in temperature; he suggests that many of the stars, like the nebulæ, are constituted of separate meteorites in continual relative motion, and become hotter and hotter through contraction of the grouping, collision, and transformation of the energy of position and motion into heat. this increase of temperature must continue during successive ages, until the energy of position and motion of the separate meteorites is wholly transformed, the separate masses having then combined to form a single white hot body which will gradually cool down to the state in which our own moon now is. if a swarm of meteorites forming one nebula be subjected to the external action of another moving swarm of meteorites, intermediate stages resembling the conditions of saturn and of the solar system may ensue. according to this spectroscopic affirmation of the nebular theory, all the heavenly bodies are constituted of the same kinds of elementary matter, those in fact which are found in meteorites and our own earth, and the difference is solely due to temperature; and a nebula in its gradual passage to the lunar condition will show every phase of spectrum observed in the stars as now existent. * * * * * [sidenote: meteorites present no evidence of life.] . finally, it may be asked whether or not meteorites bring us any tangible evidence of the existence of living beings outside our own world. to this we may briefly answer, that while an organic origin can scarcely be claimed for the graphite present in the meteoric irons, there are no less than six meteoric stones which contain, though in very minute quantity, carbon compounds of such a character that their presence in a terrestrial body would be regarded as doubtlessly an indirect result of animal or vegetable existence. on the other hand, the stony matter is such that in a terrestrial body an igneous origin would be assumed. professor maskelyne has pointed out that these carbon compounds can be completely removed without a preliminary pulverisation of the stone, and thus seem to be contained merely in the pores; he suggested that they may have been absorbed by the stones in their passage through an atmosphere containing the compounds in a state of vapour. in any case, it is impossible to prove that there is a necessary relation between these compounds of carbon and the existence of living beings. [sidenote: chondrules have been mistaken for organisms.] . in [ ] descriptions were given of sponges, corals, crinoids and plants, found in several meteorites, chiefly in that of knyahinya, but the memoir has been generally regarded as an elaborate jest. the chondrules with their excentrically radiating crystallisation are there classified and named as sponges, corals and crinoids, while the structure of meteoric iron, revealed by the widmanstätten figures, is regarded as a result of plant life. there can be no hesitation in asserting that as yet no organised matter has been found in meteorites. footnotes: [ ] remarks concerning stones said to have fallen from the clouds both in these days and in ancient times: by edward king. london, . mémoire historique et physique sur les chutes des pierres: par p. m. s. bigot de morogues. orléans, . [ ] sitzungsber. d. k. ak. d. wiss. wien. , vol. , p. . [ ] records of the geological survey of india. calcutta, , vol. , p. . [ ] ueber den ursprung der von pallas gefundenen und anderer ihr ähnlicher eisenmassen. riga, . [ ] reise durch verschiedene provinzen des russischen reichs: von p. s. pallas. st. petersburg, , part iii., p. . [ ] philosophical transactions. london, , vol. , part , pp. , . [ ] philosophical transactions. london, , vol. , p. . [ ] _ibid._, , vol. , p. . [ ] bulletin des sciences par la société philomathique. paris, , vol. , no. , p. . [ ] mémoires de l'institut national de france. , vol. , part , histoire, p. . [ ] principes de thermodynamique: par paul de saint-robert. paris, , p. . [ ] the fall of butsura: by prof. maskelyne. phil. mag. , vol. , p. . [ ] die chemische natur der meteoriten: von c. rammelsberg. berlin, - . météorites: par s. meunier. paris, . meteoritenkunde: von e. cohen. stuttgart, - . [ ] some lecture-notes on meteorites: by prof. maskelyne. _nature_, , vol. , pp. , , . [ ] Études synthétiques de géologie expérimentale. paris, . p. . [ ] phil. mag. , ser. , vol. , p. . [ ] _nature_, , vol. , p. . [ ] neues jahrbuch für mineralogie, , band i, p. . [ ] denksch. d. math-naturw. klasse d. k. ak. d. wiss., , band , p. . [ ] philosophical transactions, london, , ser. a, vol. , p. . [ ] mineralogical magazine. london, , vol. , p. . [ ] beschreibung und eintheilung der meteoriten. berlin, . [ ] die mikroskopische beschaffenheit der meteoriten: von g. tschermak. stuttgart, - . [ ] pogg. ann. , vol. , p. : phil. mag. , ser. , vol. , p. . [ ] on the structure and origin of meteorites. _nature_, , vol. , p. . [ ] die meteoritensammlung d.k.k. min. hofkabinetes in wien. , p. . [ ] lithological studies. cambridge, u.s.a. , p. . [ ] speculations on the source of meteorites. _nature_, , vol. , p. . [ ] _olmsted._ american jour. sc., , ser. , vol. , p. . [ ] _newton._ american jour. sc., , ser. , vol. , p. ; vol. , p. . [ ] report brit. assoc., , p. . [ ] pogg. ann., , vol. , p. . [ ] denning. _nature_, , vol. , p. . 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[ ] die meteorite (chondrite) und ihre organismen: von dr. o. hahn. tübingen, . list of the meteorites represented in the collection on may , . * * * * * _the references in the second column correspond with numbers and letters on the cases, and indicate the pane behind which the meteorite will be found._ * * * * * weights under one gram are not given. , grams are equivalent to · avdp. lbs. * * * * * i. siderites or meteoric irons (_consisting chiefly of nickeliferous iron, and enclosing schreibersite, troilite, graphite, &c._). * * * * * a. fall recorded. [arranged chronologically.] +----+------+------------------------------+-------------------+---------+ |no. |pane. | name of meteorite and | date of fall. | weight | | | | place of fall. | |in grams.| +----+------+------------------------------+-------------------+---------+ | | c |agram (hraschina), croatia, |may , . | | | | |austria. | | | | | | | | | | | c |charlotte, dickson county, |july , or} . | | | | |tennessee, u.s.a. |aug. , } | | | | | | | | | | c, l|braunau (hauptmannsdorf), |july , . | | | | |bohemia. | | | | | | | | | | | c, l|victoria west, cape colony, | fell in . | | | | |south africa. | | | | | | | | | | | c, h|nedagolla, mirangi, |jan. , . | , | | | |vizagapatam, madras, india. | | | | | | | | | | | c |rowton, near wellington, |april , . | , | | | |shropshire. | | | | | | | | | | | c |mazapil, zacatecas, mexico. |nov. , . | | | | | | | | | | c |cabin creek, johnson county, |march , . | | | | |arkansas, u.s.a. | | | | | | | | | | | c |n'goureyma, djenne, massina, |june , . | | | | |north-west africa. | | | +----+------+------------------------------+-------------------+---------+ b. fall not recorded. [arranged topographically.] +----+------+------------------------------+-------------------+---------+ |no. |pane. | name of meteorite and | report of find. | weight | | | | place of find. | |in grams.| +----+------+------------------------------+-------------------+---------+ | | c |la caille, near grasse, alpes |acad. sci. | | | | |maritimes, france. |bordeaux, , | | | | | |p. . | | | | |for about two centuries it was| | | | | |in front of the church of la | | | | | |caille and was used as a seat:| | | | | |its meteoric origin was | | | | | |recognised by brard in . | | | | | | | | | | | c |sÃo juliÃo de moreira, ponte |comm. da commiss. | | | | |de lima, minho, portugal. |d. trab. geol. de | | | | | |portugal, , | | | | |known since : described by|vol. , p. . | | | | |ben-saude in . | | | | | | | | | | | a |obernkirchen, near bückeburg, |pogg. ann. , | , | | | |schaumburg-lippe, germany. |vol. , p. . | | | | | | | | | | |found in a quarry on the | | | | | |bückeberg feet below the | | | | | |surface, and thrown aside: | | | | | |recognised as meteoric by | | | | | |wicke and wöhler, in . | | | | | | | | | | | d |bitburg, rhenish prussia. |schweigg. journ. | , | | | | | , vol. , | | | | |dug up about , taken to |p. . | | | | |trèves and put into a furnace:| | | | | |afterwards thrown away with | | | | | |the waste: later, fragments of| | | | | |it having been recognised by | | | | | |gibbs as meteoric, the mass | | | | | |was searched for by nöggerath | | | | | |and re-discovered in . | | | | | | | | | | | d, l|seelÄsgen, brandenburg, |pogg. ann. , | , | | | |prussia. |vol. , p. ; | | | | | | , vol. , | | | | |found in draining a field: |p. . | | | | |several years afterwards, in | | | | | | , it was met with by | | | | | |hartig and recognised as | | | | | |meteoric. | | | | | | | | | | | d |schwetz, prussia. |pogg. ann. , | , | | | | |vol. , p. . | | | | |found in in making a | | | | | |road; it was about feet | | | | | |below the surface: described | | | | | |by rose in . | | | | | | | | | | | d |nenntmannsdorf, pirna, |sitzungs-ber. d. n.| | | | |saxony. |g. isis in dresden,| | | | | | , p. . | | | | |found in about feet | | | | | |below the surface: reported by| | | | | |geinitz in . | | | | | | | | | | | d |tabarz, near gotha, germany. |ann. chem. pharm. | | | | | | , vol. , p. | | | | |said to have been seen by a | . | | | | |shepherd to fall on oct. , | | | | | | : described in by | | | | | |eberhard, to whom the rust | | | | | |seemed incompatible with a | | | | | |recent fall. | | | | | | | | | | | d |elbogen, bohemia. |gilb. ann. , | | | | | |vol. , p. . | | | | |preserved for centuries at the| | | | | |rathhaus of elbogen: its | | | | | |meteoric origin was recognised| | | | | |by neumann in . | | | | | | | | | | | d |bohumilitz, prachin, bohemia. |verh. ges. mus. | | | | | |böhm. april , | | | | |laid bare by heavy rain in | , p. . | | | | | . | | | | | | | | | | | d |lÉnÁrto, sáros, hungary. |gilb. ann. , | , | | | | |vol. , p. . | | | | |found in : described by | | | | | |tehel in . | | | | | | | | | | | d |arva (szlanicza), hungary. |pogg. ann. , | , | | | | |vol. , p. . | | | | |made known by haidinger in | | | | | | . | | | | | | | | | | | d |nagy-vÁzsony, veszprim, |ann. d. k. k. | | | | |hungary. |naturh. hofmus. | | | | | |wien, , vol. | | | | |found in : described by | , pp. , . | | | | |brezina in . | | | | | | | | | | | | | | | | | d |tula (netschaëvo), russia. |wien. akad. ber., | , | | | | | ( ), vol. | | | | |found in in making a | , p. . | | | | |road: it was feet below the | | | | | |surface: recognised as | | | | | |meteoric by auerbach in . | | | | | | | | | | | d |sarepta, saratov, russia. |bull. soc. nat. | | | | | |moscow, , p. | | | | |found in : reported by | . | | | | |auerbach in the same year. | | | | | | | | | | | d |verkhne-dnieprovsk, | | | | | |ekaterinoslav, russia. | | | | | | | | | | | |found in . | | | | | | | | | | | d |augustinovka, ekaterinoslav, |comptes rendus, | | | | |russia. | , vol. , p. | | | | | | . | | | | |known before ; fragment | | | | | |described by meunier in that | | | | | |year. | | | | | | | | | | | d |bischtÜbe, nikolaev, turgai, |bull. de la soc. | , | | | |russia. |imp. des natur. de | | | | | |moscou, , | | | | |found in : described by |vol. , p. . | | | | |kislakovsky in . | | | | | | | | | | | d |petropavlovsk (gold |erman's archiv f. | | | | |washings), mrasa river, tomsk,|wiss. kunde von | | | | |asiatic russia. |russland, , | | | | | |vol. , p. . | | | | |found about feet from the | | | | | |surface: given to the director| | | | | |of the kolyvani works in | | | | | |and described by sokolovskji | | | | | |in the same year. | | | | | | | | | | | d |toubil river (taiga), |verhandl. russ.- | | | | |petropavlovsk, yeniseisk, |kais. min. ges., | | | | |asiatic russia. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |khlaponin in . | | | | | | | | | | | d |ssyromolotovo, keshma, |bull. ac. imp. des | | | | |yeniseisk, asiatic russia. |sc. de st. | | | | | |pétersb. , | | | | |known since the year : |vol. , p. . | | | | |described by göbel in . | | | | | | | | | | | e |verkhne-udinsk (niro |pogg. ann. , | , | | | |river), transbaikal, asiatic |vol. , p. . | | | | |russia. | | | | | | | | | | | |found in : noted by | | | | | |buchner in . | | | | | | | | | | | e |nochtuisk, jakutsk, | | | | | |asiatic russia. | | | | | | | | | | | |found in . | | | | | | | | | | | b |nejed (wanee banee |mineralog. | , | | | |khaled), central arabia. |magazine, , | | | | | |vol. , p. . | | | | |said to have been seen to | | | | | |fall in ; probably this | | | | | |is a mistake and the time of | | | | | |fall unknown: described by | | | | | |l. f. in . | | | | | | | | | | | e |kodaikanal, palni |proc. asiatic soc. | , | | | |hills, madura, madras, india. |of bengal, , | | | | | |january, p. . | | | | |known since : reported by |tschermak's min. | | | | |holland in : described by |u. petrog. mitth. | | | | |berwerth in . | , vol. , | | | | | |p. . | | | | | | | | | | | | | | | | e |tanokami (-yama), |jour. geol. soc. | | | | |kurifuto-g[=o]ri, [=o]mi, |t[=o]ky[=o], , | | | | |japan. |vol. , p. . | | | | | |beiträge zur | | | | |found about : described |mineralogie von | | | | |by [=o]tsuki in , and |japan. | | | | |jimbo in . |herausgegeben von | | | | | |t. wada, , | | | | | |no. , p. . | | | | | | | | | | e |uwet, southern nigeria, | | , | | | |africa. | | | | | | | | | | | e |bethany, great |jour. roy. geog. | | | | |namaqualand, south africa. |soc. of london, | | | | | | | | | | |(a) many large masses were | , vol. , p. | | | | |reported by alexander in | . | | | | |to be lying n.e. of bethany | | | | | |and near the great fish river.| | | | | |{none of the fragments given | | | | | |to alexander seem to have | | | | | |been placed in museum | | | | | |collections.} l. f. | | | | | | | | | | | |(b) bethany (lion river). |amer. jour. sc. | | | | |a large mass said to have | , ser. , vol. | | | | |been found near lion river, | , p. . | | | | |great namaqualand, was | | | | | |described by shepard in .| | | | | | | | | | | |(c) bethany (wild). a large |annals of the south| , | | | |mass which had long been known|african mus. , | | | | |to the missionaries of bethany|vol. , part , p. | | | | |was brought to cape town by | . | | | | |wild in : described by | | | | | |cohen in . | | | | | | | | | | | |(d) bethany (mukerop). four |jahreshefte des | , | | | |large masses were met with in |vereins für vaterl.| | | | | at mukerop, gibeon, great|naturk. württ., | | | | |namaqualand: described by | , vol. , p. | | | | |brezina and cohen in . | . | | | | | | | | | | |(e) bethany (springbok |mineralog. | | | | |river). a fragment ( grams) |magazine, , | | | | |found with the label "spring |vol. , p. . | | | | |bok river," among dr. h. j. | | | | | |burkart's minerals, after his | | | | | |death in . | | | | | |{all the above masses may | | | | | |have been transported at some | | | | | |time or other from the place | | | | | |indicated by alexander; their | | | | | |etched figures are similar.} | | | | | |l. f. | | | | | | | | | | | e |orange river district, south |amer. jour. sc. | | | | |africa. | , ser. , vol. | | | | | | , p. . | | | | |sent from the orange river | | | | | |district in : described by| | | | | |shepard in . | | | | | | | | | | | e |hex river mountains, |ann. d.k.k. naturh.| | | | |cape colony, south africa. |hofmus. wien, | | | | | | , vol. , pp. | | | | |found in : described by | , . | | | | |brezina in . | | | | | | | | | | | e |cape of good hope: between |mag. für den | | | | |sunday river and bushman river|neuesten zustand | | | | |(west of great fish river), |der naturkunde, von| | | | |cape colony, south africa. |j. h. voigt, , | | | | | |vol. , p. . | | | | |known long before : | | | | | |mentioned in "barrow's travels| | | | | |into the interior of south | | | | | |africa," , vol. i. p. :| | | | | |full particulars were given in| | | | | | by von dankelmann. | | | | | | | | | | | e |kokstad, griqualand east, |ann. south african | | | | |south africa. |mus. , vol. , | | | | | |p. . | | | | |known in : described by | | | | | |cohen in . | | | | | | | | | | | e |prambanan, surakarta, java. |arch. néer. | | | | | |haarlem, , | | | | |known as early as , and |vol. , p. . | | | | |probably earlier: described by| | | | | |baumhauer in . | | | | | | | | | | | f |thunda, windorah, diamantina |jour. and proc. | | | | |district, queensland, |roy. soc. of new | | | | |australia. |south wales, , | | | | | |vol. , p. . | | | | |described by liversidge in | | | | | | . | | | | | | | | | | | f |mungindi, new south wales, |rec. geol. surv. of| | | | |australia. |new south wales, | | | | | | , vol. , | | | | |found on the queensland side |p. . amer. jour.| | | | |of the borderin : |sc. , ser. , | | | | |mentioned by card in and |vol. , p. . | | | | |figured by ward in . | | | | | | | | | | | f |boogaldi, coonabarabran, new |jour. and proc. | | | | |south wales. |roy. soc. new south| | | | | |wales, , vol. | | | | |found in : described by | , p. ; and | | | | |baker in and by | , vol. , | | | | |liversidge in . |p. | | | | | | | | | | f |cowra, bathurst, new south |records of the | | | | |wales. |geol. survey of new| | | | | |south wales, , | | | | |known since : described |vol. , p. . | | | | |by card in . | | | | | | | | | | | f |narraburra, temora, new |jour. and proc. | | | | |south wales. |roy. soc. of new | | | | | |south wales, , | | | | |found in : described by |vol. , p. . | | | | |russell in and by card |rec. geol. surv. of| | | | |in . |new south wales, | | | | | | , vol. , p. | | | | | | . | | | | | | | | | | f |nocoleche, wanaaring, new |records of the | | | | |south wales. |australian mus. | | | | | | , vol. , p. | | | | |known in : described | . | | | | |by cooksey in . | | | | | | | | | | | f |rhine villa, rhine valley, |trans. of the roy. | | | | |south australia. |soc. of south | | | | | |australia, , | | | | |described by goyder in . |vol. , p. . | | | | | | | | | | sep. |cranbourne, near melbourne, |wien. akad. ber. | , , | | |stand,|victoria, australia. | , vol. , | | | | f | |abth. , p. . | | | | |(a) two large masses, found | | | | | |nearly four miles apart, have | | | | | |been known since : | | | | | |described by haidinger in | | | | | | . | | | | | | | | | | | |(b) a much smaller mass was |sitzungsber. k. pr.| | | | |found later at beaconsfield, |ak. d. wiss. zu | | | | |six miles from cranbourne: |berlin, , vol. | | | | |described by cohen in . | , p. . | | | | | | | | | | f |(c) {fragments found in | | | | | |abel's collection of minerals | | | | | |with the label "yarra yarra | | | | | |river--date " had probably| | | | | |been detached from one of the | | | | | |two masses of cranbourne.} | | | | | |l. f. | | | | | | | | | | | e |youndegin, miles e. of |mineralog. | , | | | |york, western australia. |magazine, , | | | | | |vol. , p. . | | | | |found in : described by l.| | | | | |f. in . | | | | | | | | | | | f |roebourne ( miles |records of the | , | | | |south-east of), western |australian mus. | | | | |australia. | , vol. , p. | | | | | | . amer. jour. sc.| | | | |found in : described by | , ser. , vol. | | | | |cooksey in and by ward | , p. | | | | |in . | | | | | | | | | | | f |mount stirling, western |records of the | , | | | |australia. |australian mus. | | | | | | , vol. , p. | | | | |known in : described by | . | | | | |cooksey in . | | | | | | | | | | | f |ballinoo, murchison river, |records of the | , | | | |western australia. |australian mus. | | | | | | , vol. , p. | | | | |found in : described by | . amer. jour. sc.| | | | |cooksey in and by ward in| , ser. , vol. | | | | | . | , p. . | | | | | | | | | | f |mooranoppin, western |records of the | | | | |australia. |australian mus. | | | | | | , vol. , p. | | | | |found in or before : | . amer. jour. sc.| | | | |described by cooksey in | , ser. , vol. | | | | |and by ward in . | , p. . | | | | | | | | | | m |melville bay, miles east |voyage of | | | | |of cape york, west greenland |discovery, &c., by | | | | |(ross's iron). |captain john ross. | | | | | |london, . | | | | |two knives or lance-heads with| | | | | |bone handles given to captain | | | | | |john ross in by the | | | | | |eskimos of prince regent's | | | | | |bay: one of them was figured | | | | | |by ross on page of his | | | | | |work. according to the | | | | | |eskimos, the iron had been | | | | | |obtained from a neighbouring | | | | | |mountain called sowallick. | | | | | | | | | | | |the locality of the three |northward over the | | | | |large masses was shown by an |great ice, by r. e.| | | | |eskimo to lieut. peary in |peary. london, | | | | | : by him they were later | , vol. , p. | | | | |transported to new york. | . | | | | | | | | | | f |madoc, hastings county, |amer. jour. sc. | | | | |ontario, canada. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |hunt in . | | | | | | | | | | | f |welland, ontario, canada. |proc. rochester | | | | | |ac. of sc. , | | | | |ploughed up in : described|vol. , p. . | | | | |by howell in . | | | | | | | | | | | f |thurlow, hastings county, |amer. jour. sc. | | | | |ontario, canada. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |hoffmann in . | | | | | | | | | | | f |iron creek, battle river, |proc. and trans. | | | | |north saskatchewan, canada. |roy. soc. of | | | | | |canada, , vol. | | | | |removed about : described | , sec. , p. . | | | | |by coleman in . | | | | | | | | | | | h |lockport (cambria), niagara |amer. jour. sc. | , | | | |county, new york, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |turned up by plough: described| | | | | |as meteoric by silliman in | | | | | | . | | | | | | | | | | | l |seneca river, cayuga county, |amer. jour. sc. | | | | |new york, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in , in digging a | | | | | |ditch: described by root in | | | | | | . | | | | | | | | | | | g, l|burlington, otsego county, |amer. jour. sc. | | | | |new york, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |turned up by plough some time | | | | | |previous to , and | | | | | |described by silliman in .| | | | | | | | | | | g |pittsburg (miller's run), |proc. amer. assoc. | | | | |alleghany county, |fourth meeting, | | | | |pennsylvania, u.s.a. |held aug. , | | | | | |vol. , p. . | | | | |described by silliman in :| | | | | |date of find unknown. | | | | | | | | | | | g |mount joy, adams county, |amer. jour. sc. | | | | |pennsylvania, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |howell in . | | | | | | | | | | | g |emmittsburg, frederick | | | | | |county, maryland, u.s.a. | | | | | | | | | | | |found in . | | | | | | | | | | | g |staunton, augusta county, |amer. jour. sc. | , | | | |virginia, u.s.a. | , ser. , | | | | | |vol. , p. . | | | | |five masses have been found. | | | | | |three masses, of which two at | | | | | |least were found in , were| | | | | |described by mallet in . | | | | | |a fourth was found about |amer. jour. sc. | | | | | - , thrown away, used in | , ser. , | | | | |the construction of a stone |vol. , p. . | | | | |fence, then as an anvil; was | | | | | |next built into a wall: in | | | | | | it was taken out, and its| | | | | |meteoric nature was recognised| | | | | |by mallet. | | | | | | | | | | | |a fifth was described by kunz |amer. jour. sc. | | | | |in . | , ser. , | | | | | |vol. , p. . | | | | | | | | | | g |indian valley township, |tschermak's min. | | | | |floyd county, virginia, u.s.a.|u. petrog. mitth. | | | | | | , vol. , | | | | |found in : described by |p. . | | | | |kunz and weinschenk in . | | | | | | | | | | | g |greenbrier county (near the |mineralog. | , | | | |summit of the alleghany |magazine, , | | | | |mountain, miles north of |vol. , p. . | | | | |white sulphur springs), west | | | | | |virginia, u.s.a. | | | | | | | | | | | |found about : described | | | | | |by l. f. in . | | | | | | | | | | | g |jenny's creek, wayne county, |proc. amer. assoc. | | | | |west virginia, u.s.a. |for the year , | | | | | |vol. , p. . | | | | |the first piece was found | | | | | |before the spring of and | | | | | |lost sight of; two other | | | | | |pieces were found in and | | | | | | respectively: reported by| | | | | |kunz in . | | | | | | | | | | | h |smith's mountain, rockingham |rep. geol. surv. | | | | |county, n. carolina, u.s.a. |n. carolina, by | | | | | |kerr: raleigh, | | | | |reported by genth in to | , vol. , | | | | |have been found in . |app. c, p. . | | | | | | | | | | |reported by smith in to |amer. jour. sc. | | | | |have passed into the hands of | , ser. , | | | | |kerr about . |vol. , p. . | | | | | | | | | | |no mention of date of find by |minerals and | | | | |genth when describing the |mineral localities | | | | |meteorite in . |of north carolina, | | | | | |by genth and kerr: | | | | | |raleigh, , | | | | | |p. . | | | | | | | | | | h |deep springs (farm), |amer. jour. sc. | | | | |rockingham county, n. | , ser. , vol. | | | | |carolina, u.s.a. | , p. . | | | | | | | | | | |known since about : | | | | | |described by venable in . | | | | | | | | | | | h |guilford county, n. carolina, |amer. jour. sc. | | | | |u.s.a. | , ser. , vol. | | | | | | , p. ; and | | | | |date of find unknown: first | , vol. , p. | | | | |described by shepard as | . | | | | |terrestrial in , but in | | | | | | its meteoric origin was | | | | | |recognised by him. | | | | | | | | | | | h |lick creek, davidson county, |amer. jour. sc. | | | | |north carolina, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |hidden in . | | | | | | | | | | | h |linnville mountain, burke |amer. jour. sc. | | | | |county, n. carolina, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found about : described | | | | | |by kunz in . | | | | | | | | | | | h |ellenboro', rutherford |amer. jour. sc. | | | | |county, n. carolina, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |eakins in . | | | | | | | | | | | h |bridgewater, burke county, n. |amer. jour. sc. | | | | |carolina, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found by a ploughman: | | | | | |described by kunz in . | | | | | | | | | | a| h, l|jewell hill, walnut mtns., |amer. jour. sc. | | | | |madison county, n. | , ser. , vol. | | | | |carolina, u.s.a. | , p. ; and | | | | | |orig. res. in min. | | | | |(a) one was given to smith |and chem. by | | | | |in , and described by him |lawrence smith, | | | | |in . | , p. . | | | | | | | | | b| h |(b) a second was found in |amer. jour. sc. | | | | |use in , supporting a | , ser. , vol. | | | | |corner of a rail-fence: | , p. . the | | | | |described as from duel hill |minerals and | | | | |by burton in . the etched |mineral localities | | | | |figures are different for the |of north carolina, | | | | |two masses. |by genth and kerr: | | | | | |raleigh, , p. | | | | | | . | | | | | | | | | | h |black mountain, m. e. of |amer. jour. sc. | | | | |asheville, buncombe county, | , ser. , vol. | | | | |n. carolina, u.s.a. | , p. . | | | | | | | | | | |found about , and | | | | | |described by shepard in . | | | | | | | | | | | h |asheville (baird's |amer. jour. sc. | | | | |plantation, m. n. of), | , ser. , vol. | | | | |buncombe county, n. carolina, | , p. ; and | | | | |u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found loose in the soil: | | | | | |described by shepard in . | | | | | | | | | | | h |murphy, cherokee county, n. |amer. jour. sc. | , | | | |carolina, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in : described in | | | | | |the same year by ward. | | | | | | | | | | | k |chesterville, chester |amer. jour. sc. | , | | | |county, s. carolina, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |ploughed up several years | | | | | |before , when it was | | | | | |described by shepard. | | | | | | | | | | | k |laurens county, s. carolina, |amer. jour. sc. | | | | |u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |by hidden in . | | | | | | | | | | | k |ruff's mountain, lexington |amer. jour. sc. | | | | |county, s. carolina, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |date of find not stated: | | | | | |described by shepard in . | | | | | | | | | | | k |lexington county, s. |amer. jour. sc. | | | | |carolina, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |shepard in . | | | | | | | | | | | k |union county, georgia, |amer. jour. sc. | | | | |u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |shepard in . | | | | | | | | | | | k |whitfield county (dalton), |amer. jour. sc. | | | | |georgia, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |first specimen found in : | | | | | |particulars of find, and | | | | | |description, given by hidden | | | | | |in . | | | | | | | | | | | |a second specimen was found |amer. jour. sc. | | | | |in , and described by | , ser. , vol. | | | | |shepard in . | , p. . | | | | | | | | | | l |losttown ( - / m. s.w. of), |amer. jour. sc. | | | | |cherokee county, georgia, | , ser. , vol. | | | | |u.s.a. | , p. . | | | | | | | | | | |ploughed up in : described| | | | | |in the same year by shepard. | | | | | | | | | | | l |canton, cherokee county, |amer. jour. sc. | | | | |georgia, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |ploughed up in : described| | | | | |by howell in . according | | | | | |to brezina, canton and | | | | | |losttown probably belong to | | | | | |the same fall. | | | | | | | | | | | l |holland's store, chattooga |amer. jour. sc. | | | | |county, georgia, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |kunz in the same year. | | | | | | | | | | | l |forsyth county, georgia (not |amer. jour. sc. | | | | |n. carolina), u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found about : described by|sitzungsber. k. pr.| | | | |schweinitz in and cohen |ak. d. wiss. zu | | | | |in ; the former gives the |berlin, , | | | | |state as "n. carolina." |p. . | | | | | | | | | | | | | | | | l |locust grove, henry county, |sitzungsber. k. pr.| | | | |georgia, (? n. carolina), |ak. d. wiss. zu | | | | |u.s.a. |berlin, , p. | | | | | | . | | | | |found in : described by | | | | | |cohen in , who gives the | | | | | |state as "n. carolina." | | | | | | | | | | | l |putnam county, georgia, |amer. jour. sc. | | | | |u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |willet in . | | | | | | | | | | | l |chulafinnee, cleberne county, |amer. jour. sc. | | | | |alabama, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |ploughed up in : described| | | | | |by hidden in . | | | | | | | | | | | | | | | | | l |auburn, lee (not macon) |amer. jour. sc. | | | | |county, alabama, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |ploughed up some years before | | | | | | , when it was described by| | | | | |shepard. | | | | | | | | | | | l |summit, blount county, |amer. jour. sc. | | | | |alabama, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |known since : described | | | | | |by kunz in the same year. | | | | | | | | | | | h |walker county, alabama, |amer. jour. sc. | , | | | |u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |troost in . | | | | | | | | | | | l |claiborne (lime creek), |amer. jour. sc. | | | | |clarke county, alabama, u.s.a.| , ser. , vol. | | | | | | , p. . | | | | |mentioned in : described | | | | | |by jackson in . | | | | | | | | | | | l |tombigbee river, choctaw and |amer. jour. sc. | , | | | |sumter counties, alabama, | , ser. , vol. | | | | |u.s.a. | , p. . | | | | | | | | | | |various masses found about | | | | | | and afterwards: | | | | | |described by foote in . | | | | | | | | | | | l |oktibbeha county, |amer. jour. sc. | -- | | | |mississippi, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in an indian tumulus: | | | | | |described by taylor in . | | | | | | | | | | | l |cocke county (cosby's creek), |amer. jour. sc. | , | | | |tennessee, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |described in by troost: | | | | | |date of find unknown. | | | | | | | | | | | l |babb's mill, green county, |amer. jour. sc. | , | | | |tennessee, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |turned up by a plough: first | | | | | |mentioned in : described | | | | | |by troost in . | | | | | | | | | | | l |tazewell, claiborne county, |amer. jour. sc. | | | | |tennessee, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |turned up by a plough in :| | | | | |described by shepard in . | | | | | | | | | | | l |waldron ridge, claiborne |amer. jour. sc. | | | | |county, tennessee, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |known since : described | | | | | |by kunz in the same year. | | | | | | | | | | | l |cleveland, bradley county, |proc. ac. nat. sc. | | | | |tennessee, u.s.a. |philad. , p. | | | | | | . | | | | |this mass was acquired in | | | | | |by lea, and described by genth| | | | | |in . | | | | | | | | | | | l |jackson county, tennessee, |amer. jour. sc. | | | | |u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |date of find unknown: | | | | | |described in by troost. | | | | | | | | | | | m |carthage, smith county, |amer. jour. sc. | , | | | |tennessee, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found about : described | | | | | |in by troost. | | | | | | | | | | | l |caney fork, de kalb county, |amer. jour. sc. | | | | |tennessee, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |turned up by a plough, near | | | | | |the mouth of the caney fork | | | | | |("caryfort"), date not | | | | | |mentioned: described by | | | | | |troost in . | | | | | | | | | | | l |smithville, de kalb county, |proc. amer. ac. | , | | | |tennessee, u.s.a. |arts & sci. : | | | | | |new series, vol. | | | | |three masses were ploughed up | , p. . | | | | |in - : described by | | | | | |huntington in . | | | | | | | | | | | l |murfreesboro', rutherford |amer. jour. sc. | , | | | |county, tennessee, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found about - : described | | | | | |in by troost. | | | | | | | | | | | l |coopertown, robertson county, |amer. jour. sc. | | | | |tennessee, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |sent to smith in : | | | | | |described by him in . | | | | | | | | | | | m |kenton county ( miles south |amer. jour. sc. | , | | | |of independence), kentucky, | , ser. , vol. | | | | |u.s.a. | , p. . | | | | | | | | | | |found in : described by | | | | | |preston in . | | | | | | | | | | | m, l|lagrange, oldham county, |amer. jour. sc. | | | | |kentucky, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |smith in . | | | | | | | | | | | m |frankfort ( miles s.w. of), |amer. jour. sc. | | | | |franklin county, kentucky, | , ser. , vol. | | | | |u.s.a. | , p. . | | | | | | | | | | |found in : described | | | | | |( ) by smith. | | | | | | | | | | | m, |salt river, about miles |proc. amer. assoc. | | | | l |below louisville, kentucky, |fourth meeting, | | | | |u.s.a. |held aug. , | | | | | |vol. , p. . | | | | |date of find not mentioned: | | | | | |described by silliman in .| | | | | | | | | | | m, l|nelson county, kentucky, |amer. jour. sc. | , | | | |u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |turned up by a plough in :| | | | | |described by smith in the same| | | | | |year. | | | | | | | | | | | m |casey county, kentucky, |amer. jour. sc. | | | | |u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |mentioned in by smith. | | | | | | | | | | | m |scottsville, allen county, |amer. jour. sc. | | | | |kentucky, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |whitfield in . | | | | | | | | | | | m |smithland, livingston county, |amer. jour. sc. | , | | | |kentucky, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found about - , and | | | | | |described in by troost. | | | | | | | | | | | m |marshall county, kentucky, |amer. jour. sc. | | | | |u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |described by smith in . | | | | | | | | | | | m |wayne county (near wooster), |amer. jour. sc. | | | | |ohio, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found about : described | | | | | |by smith in . | | | | | | | | | | | m |grand rapids, kent county, |amer. jour. sc. | , | | | |michigan, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in about feet | | | | | |below the surface: reported | | | | | |by eastman in . | | | | | | | | | | | m |reed city, osceola county, |proc. rochester ac.| | | | |michigan, u.s.a. |u.s.a. of sc., | | | | | | , vol. , p. | | | | |found in : described by | . | | | | |preston in . | | | | | | | | | | | m |howard county ( miles s.e. |amer. jour. sc. | | | | |of kokomo), indiana, u.s.a. | , ser. , vol. | | | | | | , p. ; and | | | | |found in or at a | , ser. , vol. | | | | |depth of feet: described by | , p. . | | | | |cox in and by smith in | | | | | | . | | | | | | | | | | | m |plymouth, marshall county, |amer. jour. sc. | | | | |indiana, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in by a ploughman: | | | | | |described by ward in . | | | | | | | | | | | m |independence county (about |school of mines | | | | |miles east of batesville), |quarterly, , | | | | |arkansas, u.s.a. |vol. , no. , | | | | | |jan., p. . | | | | |found in : described by | | | | | |hidden in . | | | | | | | | | | | n |south-east missouri, u.s.a. |amer. jour. sc. | | | | | | , ser. , vol. | | | | |found in in the museum | , p. . | | | | |of st. louis, labelled | | | | | |"south-east missouri": | | | | | |reported by shepard in . | | | | | | | | | | | p |st. genevieve county, |proc. rochester ac.| , | | | |missouri, u.s.a. |of sci., , vol.| | | | | | , p. . | | | | |found in : described by | | | | | |ward in . | | | | | | | | | | | n |central missouri, u.s.a. |amer. jour. sc. | | | | | | , ser. , vol. | | | | |found about - : described| , p. . | | | | |by preston in . | | | | | | | | | | | n |butler, bates county, |amer. jour. sc. | | | | |missouri, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |turned up by a plough: long | | | | | |afterwards came to the | | | | | |knowledge of broadhead, who | | | | | |mentioned it in . | | | | | | | | | | | n |billings, christian county, |amer. jour. sc. | | | | |missouri, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |ward in . | | | | | | | | | | | n |arlington, sibley county, |amer. geologist, | | | | |minnesota, u.s.a. | , vol. , p. | | | | | | . | | | | |found in : described by | | | | | |winchell in . | | | | | | | | | | | n |trenton, washington county, |smithson. rep. for | | | | |wisconsin, u.s.a. | : p. . | | | | | | | | | | |turned up by a plough in :| | | | | |described by dörflinger in | | | | | | . | | | | | | | | | | | n |hammond township, st. croix |amer. jour. sc. | | | | |county, wisconsin, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |ploughed up in : described| | | | | |by fisher in . | | | | | | | | | | | n |algoma, kewaunee county, |bull. geol. soc. | | | | |wisconsin, u.s.a. |america, , vol.| | | | | | , p. . | | | | |found in : described by | | | | | |hobbs in ( ). | | | | | | | | | | | n |dakota, u.s.a. |amer. jour. sc. | | | | | | , ser. , vol. | | | | |described in by jackson. | , p. . | | | | | | | | | | n |jamestown ( or miles |proc. amer. ac. | , | | | |south-east of), stutsman |arts & sci. , | | | | |county, n. dakota, u.s.a. |vol. (new ser., | | | | | |vol. ), p. . | | | | |found in : described by | | | | | |huntington in . | | | | | | | | | | | n |niagara, grand forks county, |jour. of geology, | | | | |n. dakota, u.s.a. | , vol. , p. | | | | | | . | | | | |found in : described by | | | | | |preston in . | | | | | | | | | | | n |nebraska ( m. n.w. of fort |trans. of st. louis| , | | | |pierre), dakota, u.s.a. |acad. of sc. | | | | | | - , vol. , p.| | | | |brought away in : | . | | | | |described by holmes in . | | | | | | | | | | | n |crow creek, laramie county, |amer. jour. sc. | | | | |wyoming, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |kunz in . | | | | | | | | | | | n |illinois gulch, deer lodge |amer. jour. sc. | | | | |county, montana, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |preston in . | | | | | | | | | | | n |tonganoxie, leavenworth |amer. jour. sc. | | | | |county, kansas, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |bailey in . | | | | | | | | | | | n |russel gulch, gilpin county, |amer. jour. sc. | | | | |colorado, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in : described in | | | | | | by smith. | | | | | | | | | | | n |bear creek, denver, colorado, |amer. jour. sc. | | | | |u.s.a. | , ser. , vol. | | | | | | , pp. , . | | | | |found in : described by | | | | | |shepard in the same year. | | | | | | | | | | | n |franceville, el paso county, |proc. rochester ac.| | | | |colorado, u.s.a. |of sci., , vol.| | | | | | , p. . | | | | |found in : described by | | | | | |preston in . | | | | | | | | | | | n |hayden creek, lemhi county, |amer. jour. sc. | | | | |idaho, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |known in : described by | | | | | |hidden in . | | | | | | | | | | | m |willamette, clackamas county, |proc. rochester ac.| | | | |oregon, u.s.a. |of sci., , vol.| | | | | | , p. . | | | | |found in : described by |amer. mus. jour. | | | | |ward in and by hovey in | , vol. , p. | | | | | . | . | | | | | | | | | | o |canyon city, trinity county, |amer. jour. sc. | | | | |california, u.s.a. | , ser. , vol. | | | | | | , p. ; and | | | | |found in : described by | ser. , vol. | | | | |shepard in and by ward | , p. . | | | | |in . | | | | | | | | | | | o |oroville, butte county, | | | | | |california, u.s.a. | | | | | | | | | | | |found in . | | | | | | | | | | | o |shingle springs, el dorado |amer. jour. sc. | | | | |county, california, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found - : described by | | | | | |silliman in . | | | | | | | | | | | o |ivanpah, san bernardino |amer. jour. sc. | | | | |county, california, u.s.a. | , ser. , vol. | | | | | | , p. | | | | |described by shepard in , | | | | | |shortly after its discovery. | | | | | | | | | | | o |surprise springs, bagdad, san |mittheil. naturw. | | | | |bernardino county, s. |verein für | | | | |california, u.s.a. |neu-vorpommern und | | | | | |rügen, , | | | | |found in : described by |jahrg. , p. . | | | | |cohen in . | | | | | | | | | | | sep. |caÑon diablo, arizona, u.s.a. |amer. jour. sc. | , | | |stand,| | , ser. , vol. | | | | n |found in : described by | , p. . | | | | |foote in the same year. | | | | | | | | | | | n |weaver's mountains, | | | | | |wickenburg, arizona, u.s.a. | | | | | | | | | | | |found in . | | | | | | | | | | | n |tucson, arizona, u.s.a. |mineralog. | | | | | |magazine, , | | | | |two large masses, long |vol. , p. . | | | | |preserved at tucson, had been | | | | | |transported to that town from | | | | | |the puerto de los muchachos, | | | | | |a pass about or miles | | | | | |south of tucson. their | | | | | |existence has been known for | | | | | |centuries. one of them has | | | | | |been termed the signet or | | | | | |irwin-ainsa iron, the other | | | | | |the carleton iron. | | | | | | | | | | | o |costilla peak, cimarron |proc. colorado | , | | | |range, new mexico, u.s.a. |scient. soc. , | | | | | |vol. , p. . | | | | |found in by a | | | | | |sheep-herder: described by | | | | | |hills in . | | | | | | | | | | | o |capitan range, new mexico, |amer. jour. sc. | | | | |u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in by a | | | | | |sheep-herder: described by | | | | | |howell in . | | | | | | | | | | a| o |glorieta mountain, m. n.e. |amer. jour. sc. | , | | | |of canoncito, santa fé county,| , ser. , vol. | | | | |new mexico, u.s.a. | , p. . | | | | | | | | | | |found in : described by | | | | | |kunz in . | | | | | | | | | | b| o |a specimen probably from this |proc. colorado | | | | |locality was sent in to |scient. soc. , | | | | |denver from albuquerque, new |vol. , p. ; | | | | |mexico, as silver bullion: | , vol. , pp. | | | | |described by pearce and eakins| , . | | | | |in - . | | | | | | | | | | | o |sacramento mountains, eddy |amer. jour. sc. | , | | | |county, new mexico, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |known in : described by | | | | | |foote in ( ). | | | | | | | | | | | o |luis lopez, socorro county, |amer. jour. sc. | | | | |new mexico, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |preston in . | | | | | | | | | | | o |oscuro mountain, socorro |proc. colorado | | | | |county, new mexico, u.s.a. |scient. soc. , | | | | | |vol. , p. . | | | | |found in : described by | | | | | |hills in . | | | | | | | | | | | o |brazos river, wichita county, |trans. of st. louis| , | | | |texas, u.s.a. |acad. of sc. | | | | | | - , vol. , p.| | | | |known to the comanches for | . | | | | |many years: removed in : |amer. jour. sc. | | | | |described by shumard in , | , ser. , vol. | | | | |and by mallet in . | , p. . | | | | | | | | | | | | | | | | o |denton county, texas, u.s.a. |trans. of st. louis| | | | | |acad. of sc. | | | | |after discovery it remained | - , vol. , p.| | | | |with a blacksmith for several | . | | | | |months; in it came into | | | | | |the possession of shumard, by | | | | | |whom it was described in the | | | | | |following year. | | | | | | | | | | | o |red river (cross timbers), |amer. min. jour. by| | | | |johnson county, texas, u.s.a. |bruce: , vol. | | | | | | , pp. , . | | | | |mentioned in to captain |amer. jour. sc. | | | | |glass, and reported by gibbs | , ser. , vol. | | | | |in . | , p. . | | | | | | | | | | | | | | | | n |carlton, hamilton county, |proc. rochester ac.| , | | | |texas, u.s.a. |of sc., , vol. | | | | |ploughed up in - : | , p. . | | | | |described by howell in . |amer. jour. sc. | | | | | | , ser. , vol. | | | | | | , p. . | | | | | | | | | | o |kendall county, san antonio, |ann. d. k. k. | | | | |texas, u.s.a. |naturhist. | | | | | |hofmuseums, , | | | | |mentioned in by brezina, |band ii., notizen, | | | | |and fully described later by |p. ; cohen, | | | | |brezina and cohen. |meteoritenkunde, | | | | | | , heft iii., p.| | | | | | . | | | | | | | | | | o |mart, mclennan county, |proc. washington | | | | |texas, u.s.a. |acad. sci. , | | | | | |vol. , p. . | | | | |found in : described by | | | | | |merrill and stokes in | | | | | |( ). | | | | | | | | | | | o |san angelo, tom green |amer. jour. sc. | | | | |county, texas, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |preston in . | | | | | | | | | | | o |fort duncan, maverick |mineralog. | , | | | |county, texas, u.s.a. |magazine, , | | | | | |vol. , p. . | | | | |found in : described by | | | | | |hidden in : similar to | | | | | |coahuila; perhaps transported | | | | | |from the same district by way | | | | | |of santa rosa. | | | | | | | | | | a| c |coahuila, mexico. |mineralog. | , | | | | |magazine, , | | | | |since many masses have |vol. , p. . | | | | |been brought to santa rosa, | | | | | |from a district of small area | | | | | |about miles north-west of | | | | | |that town. an account of a | | | | | |visit by hamilton was | | | | | |published by shepard in ; | | | | | |he designated the iron by the | | | | | |name bonanza: eight large | | | | | |masses were removed to the | | | | | |united states by butcher in | | | | | | . | | | | | | | | | | b| c |sanchez estate, coahuila, |mineralog. | | | | |mexico. |magazine, , | | | | | |vol. , p. . | | | | |found in by couch in use | | | | | |as an anvil at saltillo. it | | | | | |was said to have been brought | | | | | |to that town from the "sancha | | | | | |estate," but had probably been| | | | | |acquired still earlier at | | | | | |santa rosa, and been got at | | | | | |the north-west locality. | | | | | | | | | | | c |sierra blanca, huejuquilla |mineralog. | | | | |or jimenez, chihuahua, mexico.|magazine, , | | | | | |vol. , p. . | | | | |the occurrence at sierra | | | | | |blanca was recorded in : | | | | | |the only specimen known--that | | | | | |from the bergemann | | | | | |collection--is now thought to | | | | | |be of doubtful authenticity; | | | | | |in its etched figures it is | | | | | |like toluca. | | | | | | | | | | | c |concepcion: (huejuquilla or |mineralog. | | | | |jimenez, chihuahua, mexico). |magazine, , | | | | | |vol. , p. . | | | | |masses of iron, some of them | | | | | |probably belonging to one | | | | | |fall, have been known for | | | | | |centuries to exist near | | | | | |huejuquilla: the mass is said | | | | | |to have been transported to | | | | | |concepcion from sierra de las | | | | | |adargas in . | | | | | | | | | | | c |chupaderos, chihuahua, |mineralog. | , | | | |mexico. |magazine, , | | | | | |vol. , p. . | | | | |mentioned to bartlett in .| | | | | | | | | | | c |casas grandes (de malintzin), |mineralog. | | | | |chihuahua, mexico. |magazine, , | | | | | |vol. , p. . | | | | |reported by tarayre in . | | | | | | | | | | | c |moctezuma, sonora, mexico. | | | | | | | | | | | c |arispe, sonora, mexico. |proc. rochester ac.| , | | | | |sci. , vol. , | | | | |found in : described by |p. . proc. | | | | |ward in and wuensch in |colorado sci. soc. | | | | | . | , vol. , | | | | | |p. . | | | | | | | | | | c |el ranchito, bacubirito, |mineralog. | , | | | |sinaloa, mexico. |magazine, , | | | | | |vol. , p. . | | | | |found in : described by | | | | | |castillo in . | | | | | | | | | | | a |rancho de la pila, labor |mineralog. | , | | | |de guadalupe, durango, mexico.|magazine, , | | | | | |vol. , p. . | | | | |ploughed up in : described| | | | | |by häpke in . | | | | | | | | | | | c |cacaria, durango, mexico. |mineralog. | | | | | |magazine, , | | | | |reported by castillo in : |vol. , p. . | | | | |described by cohen in . |ann. d. k. k. | | | | | |naturh. hofmus. | | | | | |wien, , vol. | | | | | | , p. . | | | | | | | | | | b |san francisco del mezquital, |mineralog. | , | | | |durango, mexico. |magazine, , | | | | | |vol. , p. . | | | | |brought from mexico by general| | | | | |castelnau, and described in | | | | | | by daubrée. the above is | | | | | |the old name for the capital | | | | | |of mezquital. | | | | | | | | | | | c |bella roca, sierra de san |amer. jour. sci. | , | | | |francisco, santiago | , ser. , vol. | | | | |papasquiaro, durango, mexico. | , p. . | | | | | | | | | | |acquired by ward in : | | | | | |described by whitfield in | | | | | | . | | | | | | | | | | | c |rodeo, durango, mexico. |field columbian | | | | | |museum. publication| | | | |found about : described | . geol. series | | | | |by farrington in . | , vol. , | | | | | |no. . | | | | | | | | | | c, p|descubridora, catorce, san |mineralog. | , | | | |luis potosi, mexico. |magazine, , | | | | | |vol. , p. . | | | | |found before , and | | | | | |described by a committee in | | | | | | . | | | | | | | | | | | l |charcas, san luis potosi, |mineralog. | | | | |mexico. |magazine, , | | | | | |vol. , p. . | | | | |mentioned in by | | | | | |sonneschmid; it was then at | | | | | |the corner of the church, and | | | | | |was said to have been brought | | | | | |from san josé del sitio, | | | | | |leagues distant. in it | | | | | |was removed to paris. | | | | | | | | | | | c, l|zacatecas, mexico. |mineralog. | , | | | | |magazine, , | | | | |mentioned in ; it was said|vol. , p. . | | | | |to have been found long before| | | | | |near the quebradilla mine. | | | | | | | | | | | a |toluca, mexico. |mineralog. | , | | | c | |magazine, , | | | | l |before it was known that |vol. , p. . | | | | |masses of iron occurred in the| | | | | |neighbourhood of xiquipilco, | | | | | |valley of toluca. | | | | | | | | | | | c |cuernavaca, morelos, mexico. |mineralog. | , | | | | |magazine, , | | | | |mentioned by castillo in .|vol. , p. . | | | | | | | | | | c |yanhuitlan, misteca alta, |mineralog. | | | | |oaxaca, mexico. |magazine, , | | | | | |vol. , p. . | | | | |mentioned by del rio in . | | | | | | | | | | | c |apoala, oaxaca, mexico. |cohen, | | | | | |meteoritenkunde, | | | | |found in : mentioned by | , heft iii., | | | | |cohen in . |p. . | | | | | | | | | | d |rosario, honduras, central | | | | | |america. | | | | | | | | | | | |found in . | | | | | | | | | | | dr. |lucky hill, st. elizabeth, | | rusted. | | | |jamaica. | | | | | | | | | | | |found in about feet | | | | | |below the surface. | | | | | | | | | | | d |santa rosa (tocavita), near |ann. chim. phys. | | | | |tunja, boyaca river, colombia,| , vol. , p. | | | | |s. america. | . | | | | | | | | | | |(a) in rivero and | | | | | |boussingault made known a | | | | | |large mass of iron in use as | | | | | |an anvil at santa rosa. | | | | | | | | | | | |in the mass was placed on|amer. jour. sc. | | | | |a pillar in the market-place | , ser. , vol. | | | | |of santa rosa (de viterbo); | , p. . | | | | |in the town was visited | | | | | |by ward, who then obtained a | | | | | |large piece of the mass. | | | | | | | | | | | |(b) with other small pieces | | | | | |it had been found on a | | | | | |neighbouring hill, called | | | | | |tocavita, in : rivero and | | | | | |boussingault collected several| | | | | |specimens themselves. | | | | | | | | | | | |the large mass and the other | | | | | |small pieces have different | | | | | |characters. | | | | | | | | | | | d |rasgata, colombia, s. america.|ann. chim. phys. | | | | | | , vol. , p. | | | | |other masses of iron were seen| . | | | | |by rivero and boussingault at | | | | | |rasgata, and were said to have| | | | | |been found there. | | | | | | | | | | | b |el inca mass, from pampa de |neues jahrb. f. | , | | | |tamarugal, iquique, chili. |min. festband, | | | | | | , p. . | | | | |found in : of "octahedral"| | | | | |structure, described by rinne | | | | | |and boeke in . | | | | | | |festsch. zur feier | | | | |a fragment, having "cubic" |d. hundertjähr. | | | | |structure, from a large mass |bestehens d. | | | | |lying at a place similarly |gesellsch. naturf. | | | | |defined had been described by |freunde zu berlin, | | | | |rose in . | , p. . | | | | | | | | | | d |tarapaca, chili, s. america. | | | | | | | | | | | |known since . | | | | | | | | | | | d |la primitiva, desert of |proc. rochester ac.| | | | |tarapaca, chili, s. america. |sci. , vol. , | | | | | |p. . | | | | |known in : mentioned by | | | | | |howell in . | | | | | | | | | | | a |mount hicks, mantos blancos, |mineralog. | , | | | |about miles from |magazine, , | | | | |antofagasta, atacama, chili. |vol. , p. . | | | | | | | | | | |found about , and | | | | | |described by l. f. in . | | | | | | | | | | | d |serrania de varas, atacama, |mineralog. | , | | | |chili. |magazine, , | | | | | |vol. , p. . | | | | |found about , and | | | | | |described by l. f. in . | | | | | | | | | | | d |san cristobal, antofagasta, |sitzungsb. d. k. | | | | |atacama, chili. |preuss. ak. d. | | | | | |wissens. zu berlin,| | | | |known since : described | , i., p. . | | | | |by cohen in . | | | | | | | | | | | d |cachiyuyal, atacama, chili. |mineralog. | | | | | |magazine, , | | | | |found in : described by |vol. , p. . | | | | |domeyko in . | | | | | | | | | | | d |ilimaË, atacama, chili. |mineralog. | | | | |known since : described |magazine, , | | | | |by tschermak in . |vol. , p. . | | | | | | | | | | d |merceditas, or leagues |proc. rochester ac.| , | | | |east of chañaral, atacama, |of sc. , vol. | | | | |chili. | , p. . | | | | | | | | | | |known since : described | | | | | |by howell in . | | | | | | | | | | | d |pan de azucar, atacama, | | , | | | |chili. | | | | | | | | | | | |found about miles from the | | | | | |port of pan de azucar in .| | | | | | | | | | | d |juncal, atacama, chili. |mineralog. | | | | | |magazine, , | | | | |found in between rio |vol. , p. . | | | | |juncal and the salinas de | | | | | |pedernal: had possibly been | | | | | |transported to that place: | | | | | |described by daubrée in . | | | | | | | | | | | d |puquios, copiapo, atacama, |proc. rochester ac.| | | | |chili. |of sc. , | | | | | |vol. , p. . | | | | |found about : described | | | | | |by howell in . | | | | | | | | | | | d |the joel iron, atacama, |mineralog. | , | | | |chili. |magazine, , | | | | | |vol. , p. . | | | | |found in in an | | | | | |unspecified part of the | | | | | |desert: described by l. f. | | | | | |in . | | | | | | | | | | | d |sierra de la ternera, |tschermak's min. | | | | |atacama, chili. |u. petrog. mitth. | | | | | | , vol. , p. | | | | |described by kunz and | . | | | | |weinschenk in . | | | | | | | | | | | d |barranca blanca, between |mineralog. | , | | | |copiapo and catamarca, south |magazine, , | | | | |america. |vol. , p. . | | | | | | | | | | |found in , and described | | | | | |by l. f. in . | | | | | | | | | | | d |chili. |mineralog. | | | | | |magazine, , | | | | |owing to an interchange of |vol. , p. . | | | | |labels, the specimen was | | | | | |described in by daubrée | | | | | |as having been found in an | | | | | |unspecified locality in chili.| | | | | |according to domeyko it was | | | | | |supposed to have been found in| | | | | |the cordillera de la dehesa, | | | | | |near santiago. | | | | | | | | | | | d |angelas (oficina), chili. | | , | | | | | | | | | sep. |otumpa, gran chaco gualamba, |phil. trans. , | , | | |stand,|argentine republic. |vol. , pp. , | | | | c | | . | | | | |the occurrence of metallic |mineralog. | | | | |iron at this locality having |magazine, , | | | | |been reported, don rubin de |vol. , p. . | | | | |celis was sent in to | | | | | |investigate the matter: his | | | | | |report was published in . | | | | | | | | | | | d |bendegÓ river, bahia, brazil. |phil. trans. , | , | | | | |vol. , p. . | | | | |found in : described by | | | | | |mornay in . | | | | | | | | | | | d |santa catharina (morro do |comptes rendus, | , | | | |rocio), rio san francisco do | , vol. , p. | | | | |sul, brazil. | . | | | | | | | | | | |discovered in : described | | | | | |by lunay in : it is | | | | | |regarded by some mineralogists| | | | | |as probably of terrestrial | | | | | |origin. | | | | | | | | | | | d |caperr, rio senguerr, |mineralog. | | | | |patagonia. |magazine, , | | | | | |vol. , p. . | | | | |known before : described | | | | | |by l. f. in . | | | | | | | | | | | d |locality unknown (from prof. |ann. chem. pharm. | | | | |wöhler's collection). | , vol. , p. | | | | | | . | | | | |described by wöhler in . | | | | | | | | | | | d |locality unknown (from |amer. jour. sc. | | | | |smithsonian museum . | , ser. , vol. | | | | |collection) | , p. . | | | | | | | | | | |described by shepard in . | | | | | | | | | | | d |locality unknown (from united |amer. jour. sc. | | | | |states national museum | , ser. , vol. | | | | |collection). | , p. . | | | | | | | | | | |slice of a complete meteorite | | | | | |which was found in a | | | | | |collection of minerals formed | | | | | |by the late col. j. j. abert: | | | | | |described by riggs in . | | | +----+------+------------------------------+-------------------+---------+ ii. siderolites (consisting chiefly of nickeliferous iron and silicates, both in large proportion). * * * * * a. fall recorded. [arranged chronologically.] +----+------+------------------------------+-------------------+---------+ |no. |pane. | name of meteorite and | date of fall. | weight | | | | place of fall. | |in grams.| +----+------+------------------------------+-------------------+---------+ | | e |taney county, missouri, u.s.a.|fell about - . | , | | | | | | | | | |a fragment, sent from taney | | | | | |county, missouri, about , | | | | | | - was described by shepard| | | | | |in . | | | | | | amer. jour. sc. , ser. | | | | | | , vol. , p. . | | | | | | | | | | | |a fragment of a meteorite was | | | | | |given to cox by judge green of| | | | | |crawford county: no mention | | | | | |of place or date of find. | | | | | | sec. rep. geol. reconn. | | | | | | arkansas, , p. . | | | | | | | | | | | |green's fragment was described| | | | | |under the name of newton | | | | | |county(arkansas) by smith in | | | | | | . | | | | | | amer. jour. sc. , ser. | | | | | | , vol. , p. . | | | | | | | | | | | |a large mass was obtained by | | | | | |kunz and reported by him in | | | | | | to have really fallen in | | | | | |taney county, missouri, about | | | | | |thirty years before, and to | | | | | |have been afterwards taken to | | | | | |newton county, arkansas. | | | | | | amer. jour. sc. , ser. | | | | | | , vol. , p. . | | | | | | | | | | | e |lodran (lodhran), mooltan, |oct. , . | | | | |punjab, india. | | | | | | | | | | | a |estherville, emmet county, |may , . | , | | | |iowa, u.s.a. | | | | | | | | | | | e |veramin, teheran, persia. |may, . | | | | | | | | | | e |marjalahti, viborgs län, |june , . | , | | | |finland. | | | +----+------+------------------------------+-------------------+---------+ b. fall not recorded. [arranged topographically.] +----+------+------------------------------+-------------------+---------+ |no. |pane. | name of meteorite and | report of find. | weight | | | | place of find. | |in grams.| +----+------+------------------------------+-------------------+---------+ | | e |finmarken, norway. |mittheil. naturw. | , | | | | |verein für | | | | |found in : described by |neu-vorpommern | | | | |cohen in . |und rügen, jahrg. | | | | | | , , p. . | | | | | | | | | | e |hainholz, minden, westphalia. |pogg. ann. , | | | | | |vol. , p. . | | | | |found in : described by | | | | | |wöhler in . | | | | | | | | | | a| e |steinbach, erzgebirge, saxony.|kurze einleitung | | | | | |in einige theile | | | | |reported as "native iron" by |der bergwerks- | | | | |j. g. lehmann in . |wissenschaft, | | | | | | , p. . | | | | | | | | | b| e |rittersgrÜn, erzgebirge, |zeitsch. deutsch. | | | | |saxony. |geol. gesell. ,| | | | | |vol. , p. . | | | | |found in ( or) : |der eisenmeteorit | | | | |reported by breithaupt in |von rittersgrün im | | | | | . |sächsischen | | | | | | | | | | |according to weisbach it was |erzgebirge: von a. | | | | |really found in . |w.: freiberg, .| | | | | | | | | c| e |breitenbach, erzgebirge, |phil. trans. , | , | | | |bohemia. |vol. , p. . | | | | | | | | | | |found in : described by |berg-und hütt. | | | | |maskelyne in . |zeitung, , | | | | | |jahrg. , p. . | | | | |steinbach, rittersgrün, and | | | | | |breitenbach are within five | | | | | |english miles of each other, | | | | | |on the border of saxony and | | | | | |bohemia; the siderolites | | | | | |probably fell at the same | | | | | |time. breithaupt suggests that| | | | | |this was the fall reported to | | | | | |have taken place at | | | | | |whitsuntide in the year : | | | | | |buchner (p. ) suggests a | | | | | |fall which took place between | | | | | | and . | | | | | | | | | | | e |brahin, minsk, russia. |bull. des. sc. par | | | | | |la soc. philom., | | | | |found in , or . |_paris_, , p. | | | | | | . partsch's die | | | | | |meteoriten zu wien.| | | | | | , p. . | | | | | |erman's archiv. f. | | | | | |wiss. kunde von | | | | | |russland, , | | | | | |vol. , p. . | | | | | | | | | | e, c|the pallas iron. |reise d. versch. | , | | | | |prov. d. russ. | | | | |found in between the ubei|reichs: von p. s. | | | | |and sisim rivers, yeniseisk, |pallas. st. | | | | |asiatic russia, and |petersburg, | | | | |transported to krasnojarsk: | . part iii. | | | | |reported by pallas in . |p. . | | | | | | | | | | e |pavlodar, semipalatinsk, | | | | | |asiatic russia. | | | | | | | | | | | |found in . | | | | | | | | | | | e |senegal river, west africa. |allgemeine historie| | | | | |der reisen zu | | | | |"native iron" was found by |wasser und lande: | | | | |compagnon in to be in |von j. j. schwabe. | | | | |very common use in many parts |leipzig, , vol.| | | | |of the kingdoms of bambuk and | , book , ch. , | | | | |siratik. |p. . | | | | | | | | | | e |mount dyrring, bridgman, |records of the | | | | |singleton district, new south |geol. survey of | | | | |wales. |n. s. wales, , | | | | | |vol. , p. . | | | | |found in : described by | | | | | |card in . | | | | | | | | | | | e |powder mill creek, |amer. jour. sc. | , | | | |cumberland county, tennessee, | , ser. , vol. | | | | |u.s.a. | , pp. , . | | | | | | | | | | |found in : described in | | | | | |the same year by whitfield | | | | | |and kunz. | | | | | | | | | | | e |eagle station, carroll |amer. jour. sc. | | | | |county, kentucky, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in , and described | | | | | |by kunz in . | | | | | | | | | | | e |brenham township, kiowa |amer. jour. sc. | , | | | |county, kansas, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found about : described | | | | | |by kunz in . | | | | | | | | | | | e |admire, lyon county, kansas, |proc. u.s. nat. | , | | | |u.s.a. |mus. , vol. ,| | | | | |p. . | | | | |found about : described | | | | | |by merrill in . | | | | | | | | | | | sep. |imilac, atacama, chili. |mineralog. | , | | |stand,| |magazine, , | | | | f |known in : probably the |vol. , p. . | | | | |specimen found at campo de | | | | | |pucará in had been | | | | | |carried at some time or other | | | | | |from imilac. | | | | | | | | | | | f |ilimaes, leagues south of |proc. roch. acad. | | | | |taltal, atacama, chili. |of science, , | | | | | |vol. , p. . | | | | |found about - : described | | | | | |by ward in . | | | | | | | | | | | f |vaca muerta, atacama, chili. |mineralog. | , | | | | |magazine, , | | | | |mentioned in , and |vol. , p. . | | | | |described in by domeyko | | | | | |as found at sierra de chaco. | | | | | |specimens probably got from | | | | | |the same place are known by | | | | | |various names (mejillones, | | | | | |jarquera or janacera pass, | | | | | |&c.). | | | | | | | | | | | f |llano del inca, leagues |proc. rochester ac.| | | | |s.e. of taltal, atacama, |of sci. , vol. | | | | |chili. | , p. . | | | | | | | | | | f |doÑa inez, atacama, chili. | _ibid_. | , | | | | | | | | | |the meteorites of llano del | | | | | |inca and doña inez were found | | | | | |in these localities in , | | | | | |and were described by howell | | | | | |in : "polished sections of| | | | | |the two meteorites are in many| | | | | |cases not distinguishable," | | | | | |and howell is inclined to | | | | | |think that they belong to a | | | | | |single fall. (some of the | | | | | |polished faces are not to be | | | | | |distinguished from those of | | | | | |vaca muerta.) l. f. | | | | | | | | | | | f |copiapo, chili. |mineralog. | | | | | |magazine, , | | | | |numerous masses of this type |vol. , p. . | | | | |have been brought to copiapo | | | | | |since : some of them, | | | | | |owing to an interchange of | | | | | |labels, have been supposed to | | | | | |come from the sierra de la | | | | | |dehesa (deesa), near santiago.| | | | | | | | | +----+------+------------------------------+-------------------+---------+ iii. aerolites or meteoric stones (consisting generally of one or more silicates, and interspersed particles of nickeliferous iron, troilite, &c.). * * * * * a. fall recorded. [arranged chronologically.] +----+------+------------------------------+-------------------+---------+ |no. |pane. | name of meteorite and | date of fall. | weight | | | | place of fall. | |in grams.| +----+------+------------------------------+-------------------+---------+ | | | | | | | | c |ensisheim, elsass, germany. | nov. , | | | | | | | | | | g |schellin, near stargard, | april , | -- | | | |pomerania, prussia. | | | | | | | | | | | g |plescowitz, near reichstadt, | june , | | | | |bohemia. | | | | | | | | | | | c |ogi (haruta), hizen, kiusiu, | june , | , | | | |japan. | | | | | | | | | | | c |tabor (krawin, plan, strkow), | july , | | | | |bohemia. | | | | | | | | | | | g |luponnas, ain, france. | sept. , | | | | | | | | | | g |albareto, modena, italy. | july | | | | | | | | | | c |lucÉ (maine), sarthe, france. | sept. , | | | | | | | | | | g |mauerkirchen, upper austria. | nov. , | | | | | | | | | | g |sena, sigena, aragon, spain. | nov. , | · | | | | | | | | | g |eichstÄdt, wittmess, bavaria. | feb. , | | | | | | | | | | g |kharkov (jigalowka, bobrik), | oct. (not ),| | | | |russia. | | | | | | | | | | | g |barbotan, landes, france. | july , | | | | | | | | | | c |siena, cosona, italy. | june , | | | | | | | | | | b |wold cottage, thwing, | dec. , | , | | | |yorkshire. | | | | | | | | | | | g |bjelaja zerkov, kiev, russia. |jan. or , | | | | | | | | | | g |salles, near villefranche, |march or , | | | | |rhône, france. | | | | | | | | | | | g, c|krakhut, benares, india. | dec. , | | | | | | | | | | h, c|l'aigle, orne, france. | april , | , | | | | | | | | | h |apt (saurette), vaucluse, | oct. , | | | | |france. | | | | | | | | | | | h |mÄssing (st. nicholas), | dec. , | -- | | | |bavaria. | | | | | | | | | | | h |darmstadt, hesse, germany. | fell before | · | | | | | | | | | d |high possil, near glasgow, | april , | | | | |scotland. | | | | | | | | | | | h |hacienda de bocas, san luis | nov. , | -- | | | |potosi, mexico. | | | | | | | | | | | h |doroninsk, irkutsk, asiatic | april , | | | | |russia. | | | | | | | | | | | h |asco, corsica. | nov. | -- | | | | | | | | | n |alais, gard, france. | march , | | | | | | | | | | h |timochin, juchnov, smolensk, | march , | | | | |russia. | | | | | | | | | | | h, o|weston, fairfield county, | dec. , | , | | | |connecticut, u.s.a. | | | | | | | | | | | h |borgo san donino, cusignano, | april , | | | | |parma, italy. | | | | | | | | | | | h} |stannern: iglau, moravia, | | | | | } |austria. | | | | | d} |(a) stannern, |} may , |{ , | | | o} |(b) langenpiernitz. |} |{ | | | | | | | | | h |lissa, bunzlau, bohemia. | sept. , | | | | | | | | | | h |moradabad, north-west | fell in | | | | |provinces, india. | | | | | | | | | | | h |kikino, viasma, smolensk, | fell in | | | | |russia. | | | | | | | | | | | h |mooresfort, county tipperary, | aug. | | | | |ireland. | | | | | | | | | | | h |charsonville: meung, loiret, | | | | | |france. | | | | | |(a) charsonville, |} |{ | | | |(b) bois de fontaine, |} nov. , |{ , | | | |(c) fragment of a stone |} |{ | | | |labelled chartres. |} |{ | | | | | | | | | h |kuleschovka, poltava, russia. | march , | | | | | | | | | | h |berlanguillas, near burgos, | july , | | | | |spain. | | | | | | | | | | | k |toulouse (grenade), haute | april , | | | | |garonne, france. | | | | | | | | | | | k |erxleben, magdeburg, prussia. | april , | | | | | | | | | | k, o|chantonnay, vendée, france. | aug. , | , | | | | | | | | | k |adare (faha, &c.), county | sept. , | | | | |limerick, ireland. | | | | | | | | | | | k |luotolaks, viborg, finland. | dec. , | | | | | | | | | | k |gurram konda, between | fell in | | | | |punganur and kadapa, madras, | | | | | |india. | | | | | | | | | | | k |bachmut (alexejevka), | feb. , | | | | |ekaterinoslav, russia. | | | | | | | | | | | k |agen, lot-et-garonne, france. | sept. , | | | | | | | | | | k |chail, allahabad, north-west | nov. , | -- | | | |provinces, india. | | | | | | | | | | | k |durala, n.w. of kurnal, | feb. , | , | | | |punjab, india. | | | | | | | | | | | o |chassigny, haute marne, | oct. , | | | | |france. | | | | | | | | | | | k |zaborzika, czartorya, | april (not | | | | |volhynia, russia. | ), | | | | | | | | | | n |seres, macedonia, turkey. | june | | | | | | | | | | k |slobodka, juchnov, smolensk, | aug. , | | | | |russia. | | | | | | | | | | | l |jonzac, charente inférieure, | june , | | | | |france. | | | | | | | | | | | l |pohlitz, near gera, reuss, | oct. , | | | | |germany. | | | | | | | | | | | l |lixna (lasdany), dünaburg, | july , | | | | |vitebsk, russia. | | | | | | | | | | | o |juvinas, near libonnez, | june , | | | | |ardèche, france. | | | | | | | | | | | l |angers, maine-et-loire, | june , | | | | |france. | | | | | | | | | | | l |agra (kadonah), india. | aug. , | | | | | | | | | | l |epinal (la baffe), vosges, | sept. , | · | | | |france. | | | | | | | | | | | l, h|futtehpur (fatehpur): n. west | | | | | |provinces, india. | | | | | |(a) futtehpur |}nov. , |{ , | | | |(b) bithur. |} |{ | | | | | | | | | l |umballa ( miles s.w. of), | fell in - | | | | |punjab, india. | | | | | | | | | | | l |nobleborough, lincoln county, | aug. , | -- | | | |maine, u.s.a. | | | | | | | | | | | l |renazzo, cento, ferrara, | jan. , | | | | |italy. | | | | | | | | | | | l |zebrak (praskoles), near | oct. , | | | | |horzowitz, bohemia. | | | | | | | | | | | l |nanjemoy, charles county, | feb. , | | | | |maryland, u.s.a. | | | | | | | | | | | l |honolulu, hawaii, | sept. , | | | | |sandwich islands. | | | | | | | | | | | m |pavlograd (mordvinovka), | may , | | | | |ekaterinoslav, russia. | | | | | | | | | | | m |mhow, azamgarh district, | feb. , | | | | |north-west provinces, india. | | | | | | | | | | | m |drake creek, nashville, | may , | | | | |tennessee, u.s.a. | | | | | | | | | | | m |bialystock (jasly), grodno, | oct. , | | | | |russia. | | | | | | | | | | | m |richmond, henrico county, | june , | | | | |virginia, u.s.a. | | | | | | | | | | | m |forsyth, georgia, u.s.a. | may , | | | | | | | | | | m |deal, near long branch, | aug. , | -- | | | |new jersey, u.s.a. | | | | | | | | | | | m |krasnoi-ugol, rjäsan, russia. | sept. , | | | | | | | | | | m |launton, bicester, | feb. , | , | | | |oxfordshire. | | | | | | | | | | | m |perth (north inch of), | may , | · | | | |scotland. | | | | | | | | | | | m |vouillÉ, near poitiers, | may , | | | | |vienne, france. | | | | | | | | | | | m |wessely (znorow), hradisch, | sept. , | | | | |moravia, austria. | | | | | | | | | | | m |blansko, brünn, moravia, | nov. , | -- | | | |austria. | | | | | | | | | | | m |okniny, kremenetz, volhynia, | jan. , | | | | |russia. | | | | | | | | | | | m |charwallas (chaharwala), near | june , | | | | |hissar, delhi, india. | | | | | | | | | | | m |mascombes, corrèze, france. | jan. , | | | | | | | | | | m |aldsworth, near cirencester, | aug. , | | | | |gloucestershire. | | | | | | | | | | | m |aubres, nyons, drôme, france. | sept. , | | | | | | | | | | m |macao, rio grande do norte, | nov. , | | | | |brazil. | | | | | | | | | | | m |yon[=o]zu, nishikambara, | july , | | | | |echigo, japan. | | | | | | | | | | | m |nagy-diwina, near budetin, | july , | | | | |trentschin, hungary. | | | | | | | | | | | m |esnandes, charente | aug. | | | | |inférieure, france. | | | | | | | | | | | n |kaee, sandee district, onde, | jan. , | | | | |india. | | | | | | | | | | | n |akbarpur, saharanpur, | april , | , | | | |north-west provinces, india. | | | | | | | | | | | n |chandakapur, berar, india. | june , | | | | | | | | | | n |montlivault, loir-et-cher, | july , | | | | |france. | | | | | | | | | | | n, n|cold bokkeveld, cape colony. | oct. , | , | | | | | | | | | n |little piney (pine bluff), | feb. , | | | | |pulaski county, missouri, | | | | | |u.s.a. | | | | | | | | | | | n |karakol, ajagus, kirghiz | may , | | | | |steppes, russia. | | | | | | | | | | | n |uden (staartje), | june , | -- | | | |north brabant, netherlands. | | | | | | | | | | | n |cereseto, near ottiglio, | july , | | | | |alessandria, piedmont, italy. | | | | | | | | | | | n |grÜneberg, heinrichsau, | march , | | | | |prussian silesia. | | | | | | | | | | | n |chÂteau-renard, triguères, | june , | , | | | |loiret, france. | | | | | | | | | | | n |milena, warasdin, croatia, | april , | | | | |austria | | | | | | | | | | | n |aumiÈres, lozère, france. | june , | | | | | | | | | | o |bishopville, sumter county, | march , | | | | |s. carolina, u.s.a. | | | | | | | | | | | m, n|utrecht (blaauw-kapel), | june , | | | | |netherlands. | | | | | | | | | | | n |manegaum (manegaon), near | june , | | | | |eidulabad, border of | | | | | |khandeish, india. | | | | | | | | | | | n |klein-wenden, near | sept. , | | | | |nordhausen, erfurt, prussia. | | | | | | | | | | | n |cerro cosina, near dolores | jan. | | | | |hidalgo, san miguel, | | | | | |guanaxuato, mexico. | | | | | | | | | | | n |killeter, county tyrone, | april , | | | | |ireland. | | | | | | | | | | | n |favars, aveyron, france. | oct. , | | | | | | | | | | n |le teilleul (la vivionnère), | july , | | | | |manche, france. | | | | | | | | | | | n |monte milone (now called | may , | | | | |pollenza), macerata, italy. | | | | | | | | | | | n |cape girardeau, missouri, | aug. , | | | | |u.s.a. | | | | | | | | | | | n |schÖnenberg, mindelthal, | dec. , | | | | |schwaben, bavaria. | | | | | | | | | | | o |linn county (hartford), | feb. , | | | | |iowa, u.s.a. | | | | | | | | | | | o |castine, hancock county, | may , | | | | |maine, u.s.a. | | | | | | | | | | | o |marmande (montignac), | july , | | | | |aveyron, france. | | | | | | | | | | | o |ski, amt akershuus, norway. | dec. , | | | | | | | | | | o |cabarras county (monroe), n. | oct. , | | | | |carolina, u.s.a. | | | | | | | | | | | o |kesen(-mura), kesen-g[=o]ri, | june , | , | | | |rikuzen, japan. | | | | | | | | | | | o |shalka, bancoorah, bengal, | nov. , | , | | | |india. | | | | | | | | | | | o |gÜtersloh, westphalia, | april , | | | | |prussia. | | | | | | | | | | | o |quinÇay, vienne, france. | summer, | | | | | | | | | | o |nulles, catalonia, spain. | nov. , | | | | | | | | | | p |nellore (yatur), madras, | jan. , | , | | | |india. | | | | | | | | | | | o, d|mezÖ-madaras, transylvania. | sept. , | | | | | | | | | | o |borkut, marmoros, hungary. | oct. , | | | | | | | | | | o |bustee (basti), between | dec. , | , | | | |goruckpur and fyzabad, india. | | | | | | | | | | | o |girgenti, sicily. | feb. , | | | | | | | | | | o |segowlie, bengal, india. | march , | , | | | | | | | | | o |duruma, wanikaland, e. africa.| fell in | -- | | | | | | | | | o |linum, brandenburg, prussia. | sept. , | | | | | | | | | | c |oesel (gesinde kaande, near | may , | | | | |piddul), baltic sea. | | | | | | | | | | | c |gnarrenburg (bremervörde), | may , | | | | |hanover. | | | | | | | | | | | c |st. denis-westrem, near | june , | · | | | |ghent, belgium. | | | | | | | | | | | o |petersburg, lincoln county, | aug. , | | | | |tennessee, u.s.a. | | | | | | | | | | | c |trenzano, brescia, italy. | nov. , | | | | | | | | | | c, a|parnallee, madras, india. | feb. , | , | | | | | | | | | c |heredia, san josé, costa | april , | | | | |rica. | | | | | | | | | | | c |stavropol, north side of the | april , | | | | |caucasus, russia. | | | | | | | | | | | c |kaba, debreczin, hungary. | april , | | | | | | | | | | c |les ormes, near joigny, | oct. , | | | | |yonne, france. | | | | | | | | | | | c |ohaba (veresegyhaza), near | oct. , | | | | |karlsburg, transylvania. | | | | | | | | | | | n |pegu (quenggouk), british | dec. , | | | | |burmah. | | | | | | | | | | | c |kakowa, temeser banat, | may , | | | | |hungary. | | | | | | | | | | | c |ausson: haute garonne, france.| | | | | |(a)ausson, |} dec. , |} | | | |(b)clarac, |} |} | | | | | | | | | c |molina, murcia, spain. | dec. , | | | | | | | | | | d |harrison county, indiana, | march , | | | | |u.s.a. | | | | | | | | | | | d |pampanga (mexico), philippine | april , | · | | | |islands. | | | | | | | | | | | d |beuste, near pau, | may | | | | |basses-pyrénées, france. | | | | | | | | | | | d |bethlehem, near albany, new | aug. , | -- | | | |york, u.s.a. | | | | | | | | | | | d |alessandria (san giuliano | feb. , | | | | |vecchio), piedmont, italy. | | | | | | | | | | | n |khiragurh, s.e. of bhurtpur, | march , | | | | |india. | | | | | | | | | | | d, b|new concord, muskingum | may , | , | | | |county, ohio, u.s.a. | | | | | | | | | | | d |kusiali, kumaon, india. | june , | | | | | | | | | | c |dhurmsala (dharmsala), | july , | , | | | |kangra, punjab, india. | | | | | | | | | | | h |butsura (batsura): bengal, | | | | | |india. | | | | | |(qutahar bazaar) |} |{ , | | | |(chireya) |}may , |{ | | | |(piprassi) |} |{ , | | | |(bulloah) |} |{ | | | | | | | | | d |canellas, near barcelona, | may , | · | | | |spain. | | | | | | | | | | | d |grosnaja (mikenskoi), banks | june , | | | | |of the terek, caucasus, | | | | | |russia. | | | | | | | | | | | d |klein-menow, alt-strelitz, | oct. , | , | | | |mecklenburg, germany. | | | | | | | | | | | d |pulsora, n.e. of rutlam, | march , | | | | |indore, central india. | | | | | | | | | | | d |buschhof (scheikahr stattan), | june , | | | | |courland, russia. | | | | | | | | | | | d |pillistfer (aukoma), livland, | aug. , | | | | |russia. | | | | | | | | | | | d |shytal (shaital), miles | aug. , | | | | |north of dacca, india. | | | | | | | | | | | d |tourinnes-la-grosse, | dec. , | | | | |tirlemont, belgium. | | | | | | | | | | | d |manbhoom, bengal, india. | dec. , | | | | | | | | | | d |nerft, courland, russia. | april , | | | | | | | | | | d, d|orgueil, near montauban, | may , | | | | |tarn-et-garonne, france. | | | | | | | | | | | d |dolgovoli, volhynia, russia. | june , | | | | | | | | | | |supuhee: goruckpur district | | | | | |india. | | | | | e |(a) mouza khoorna, sidowra, |} |{ , | | | h |(b) bubuowly indigo factory, |}jan. , |{ | | | |supuhee, |} |{ | | | | | | | | | e |vernon county, wisconsin, | march , | | | | |u.s.a. | | | | | | | | | | | e |gopalpur, jessore, india. | may , | | | | | | | | | | e |dundrum, tipperary, ireland. | aug. , | | | | | | | | | | e |aumale (senhadja), | aug. , | | | | |constantine, algeria. | | | | | | | | | | | k, o|sherghotty (umjhiawar), near | aug. , | | | | |gya, behar, india. | | | | | | | | | | | n |muddoor, mysore, india. | sept. , | | | | | | | | | | e |udipi (yedabettu), south | april | , | | | |canara, india. | | | | | | | | | | | e |pokhra, near bustee, | may , | | | | |goruckpur, india. | | | | | | | | | | | e |st. mesmin, aube, france. | may , | | | | | | | | | | d, |knyahinya, near nagy-berezna, | june , | , | | | d, |hungary. | | | | | h, | | | | | | n | | | | | | | | | | | | e |jamkheir, ahmednuggur, | oct. , | | | | |bombay. | | | | | | | | | | | e |cangas de onis (elgueras), | dec. , | | | | |asturias, spain. | | | | | | | | | | | e |khetri (saonlod, sankhoo, | jan. , | | | | |phulee, &c.), rajpootana, | | | | | |india. | | | | | | | | | | | o |tadjera, near guidjel, setif, | june , | | | | |algeria. | | | | | | | | | | | e, |{ pultusk (siedlce, gostkóv, | jan. , | , | | | e-g |{ &c.), poland. | | | | | e |{ lerici, spezia, italy. | jan. , | | | | | | | | | | e, d|daniel's kuil, griqualand, | march , | | | | |south africa. | | | | | | | | | | | e |slavetic, agram, croatia, | may , | | | | |austria. | | | | | | | | | | | e |ornans, doubs, france. | july , | , | | | | | | | | | e |sauguis, st. Étienne, | sept. , | | | | |basses-pyrénées, france. | | | | | | | | | | | e |danville, morgan county, | nov. , | | | | |alabama, u.s.a. | | | | | | | | | | | e |frankfort ( miles s. of), | dec. , | | | | |franklin county, alabama, | | | | | |u.s.a. | | | | | | | | | | | e |moti-ka-nagla, ghoordha, | dec. , | | | | |bhurtpur, india. | | | | | | | | | | | o |angra dos reis, rio de | jan. | | | | |janeiro, brazil. | | | | | | | | | | | e, d|hessle, near upsala, sweden. | jan. , | | | | | | | | | | e |krÄhenberg, zweibrücken, | may , | | | | |rhenish bavaria. | | | | | | | | | | | e |clÉguÉrec (kernouvé), | may , | , | | | |morbihan, france. | | | | | | | | | | | e |tjabÉ, padangan, java. | sept. , | | | | | | | | | | e |stewart county ( miles s.w. | oct. , | | | | |of lumpkin), georgia, u.s.a. | | | | | | | | | | | f |ibbenbÜhren, westphalia, | june , | | | | |prussia. | | | | | | | | | | | f |cabeza de mayo, murcia, | aug. , | | | | |spain. | | | | | | | | | | | o |roda ( miles from), huesca, | spring | | | | |spain. | | | | | | | | | | | f |searsmont, waldo county, | may , | | | | |maine, u.s.a. | | | | | | | | | | | f |laborel, drôme, france. | june , | | | | | | | | | | f |bandong, java. | dec. , | | | | | | | | | | d |dyalpur, sultanpur, oude, | may , | | | | |india. | | | | | | | | | | | f |tennasilm (sikkensaare), | june , | | | | |esthonia, russia. | | | | | | | | | | | f |lancÉ: {authon and lancé, |} | | | | | {vendôme, |}july , | | | | | {loir-et-cher, france. |} | | | | | | | | | | o |orvinio, near rome, italy. | aug. , | | | | | | | | | | f |jhung (jhang), punjab, india. | june | , | | | | | | | | | f |khairpur, miles east of | sept. , | , | | | |bhawalpur, india. | | | | | | | | | | | f |santa barbara, rio grande do | sept. , | · | | | |sul, brazil. | | | | | | | | | | | f |aleppo, syria. | fell about | | | | | | | | | | f |sevrukovo, near belgorod, | may , | | | | |kursk, russia. | | | | | | | | | | | f |nash county (near castalia), | may , | | | | |n. carolina, u.s.a. | | | | | | | | | | | f |virba, vidin, turkey. | may , | | | | | | | | | | f |kerilis, mael pestivien, | nov. , | | | | |côtes-du-nord, france. | | | | | | | | | | | f |amana (colony) [homestead, | feb. , | , | | | |west liberty], iowa county, | | | | | |iowa, u.s.a. | | | | | | | | | | | f |sitathali (nurrah), s.e. of | march , | | | | |raepur, central provinces, | | | | | |india. | | | | | | | | | | | d |zsadÁny, temeser banat, | march , | | | | |hungary. | | | | | | | | | | | f |nagaria, fathabad, agra, | april , | | | | |india. | | | | | | | | | | | f |mornans, bourdeaux, drôme, | sept. | | | | |france. | | | | | | | | | | | n |judesegeri, kadaba taluk, | feb. , | | | | |mysore, india. | | | | | | | | | | | g |vavilovka, kherson, russia. | june , | | | | | | | | | | g |stÄlldalen, nya kopparberg, | june , | , | | | |orebro, sweden. | | | | | | | | | | | g |rochester, fulton county, | dec. , | | | | |indiana, u.s.a. | | | | | | | | | | | g |warrenton, warren county, | jan. , | | | | |missouri, u.s.a. | | | | | | | | | | | g |cynthiana ( miles from), | jan. , | | | | |harrison county, kentucky, | | | | | |u.s.a. | | | | | | | | | | | g |hungen, hesse, germany. | may , | | | | | | | | | | g |jodzie (yodzé), ponevej, | june , | · | | | |kovno, russia. | | | | | | | | | | | g |soko-banja (sarbanovac), n.e. | oct. , | , | | | |of alexinatz, servia. | | | | | | | | | | | g |cronstad, orange river | nov. , | , | | | |colony, s. africa. | | | | | | | | | | | g |bhagur (dhulia), india. | nov. , | | | | | | | | | | h |tieschitz, prerau, moravia. | july , | | | | | | | | | | h |mern, præsto, denmark. | aug. , | | | | | | | | | | h |dandapur, goruckpur, india. | sept. , | , | | | | | | | | | h |rakovka, tula, russia. | nov. , | | | | | | | | | | h |la bÉcasse, dun le poëlier, | jan. , | | | | |indre, france. | | | | | | | | | | | h |itapicuru-mirim, maranhão, | march | | | | |brazil. | | | | | | | | | | | h |gnadenfrei, prussian silesia. | may , | | | | | | | | | | h |nagaya, entre rios, argentine | july , | | | | |republic. | | | | | | | | | | | h |tomatlan (gargantillo), | sept. , | | | | |jalisco, mexico. | | | | | | | | | | | h |kalambi (kalumbi), bombay, | nov. , | | | | |india. | | | | | | | | | | | h |takenouchi (-mura), | feb. , | | | | |yabu-g[=o]ri, tajima, japan. | | | | | | | | | | | h |middlesbrough (pennyman's | march , | | | | |siding), yorkshire. | | | | | | | | | | | h |pacula, jacala, hidalgo, | june , | | | | |mexico. | | | | | | | | | | | h |gross-liebenthal, miles | nov. , | | | | |s.s.w. of odessa, russia. | | | | | | | | | | | h, |mocs, kolos, transylvania. | feb. , | , | | | k, | | | | | | d | | | | | | | | | | | | k |fukutomi (-mura), | march , | | | | |kijima-g[=o]ri, hizen, japan. | | | | | | | | | | | k |pavlovka, balachev, saratov, | aug. , | | | | |russia. | | | | | | | | | | | k |pirgunje, dinagepur, india. | aug. , | | | | | | | | | | k |saint caprais-de-quinsac, | jan. , | | | | |gironde, france. | | | | | | | | | | | k |alfianello, brescia, italy. | feb. , | , | | | | | | | | | k |ngawi, madioen, java. | oct. , | | | | | | | | | | l |pirthalla, hissar district, | feb. , | | | | |punjab, india. | | | | | | | | | | | l |djati-pengilon, alastoeva, | march , | | | | |java. | | | | | | | | | | | l |tysnes (midt-vaage), | may , | | | | |hardanger fiord, norway. | | | | | | | | | | | l |chandpur, miles n.w. of | april , | | | | |mainpuri, north-west | | | | | |provinces, india. | | | | | | | | | | | l |nammianthal, south arcot, | jan. , | , | | | |madras, india. | | | | | | | | | | | l |assisi, perugia, italy. | may , | | | | | | | | | | l |alatyr (novo-urei), | sept. , | | | | |karamzinka, petrovka, nijni | | | | | |novgorod, russia. | | | | | | | | | | | p, |oshima (-mura) [yenshigahara, | oct. , | , | | | |oynchimura], kitaisa-g[=o]ri, | | | | | |satsuma, kiusiu, japan. | | | | | | | | | | | l |bielokrynitschie, zaslavl, | jan. , | | | | |volhynia, russia. | | | | | | | | | | | l |lalitpur (jharaota), | april , | | | | |north-west provinces, india. | | | | | | | | | | | l |tabory, ochansk, perm, | aug. , | , | | | |russia. | | | | | | | | | | | l |lundsgÅrd, ljungby, sweden. | april , | | | | | | | | | | l |migheja, olviopol, | june , | | | | |elizabetgrad, kherson, south | | | | | |russia. | | | | | | | | | | | l |ergheo, brava, somaliland. | july | | | | | | | | | | l |jelica, servia. | dec. , | , | | | | | | | | | m |collescipoli (antifona), | feb. , | | | | |terni, italy. | | | | | | | | | | | m |baldohn, misshof, courland, | april , | | | | |russia. | | | | | | | | | | | m |winnebago county (forest | may , | , | | | |city), iowa, u.s.a. | | | | | | | | | | | m |kahangarai, tirupatúr, salem, | june , | | | | |madras, india. | | | | | | | | | | | m |nawapali, sambalpur district, | june , | | | | |central provinces, india. | | | | | | | | | | | m |farmington, washington | june , | | | | |county, kansas, u.s.a. | | | | | | | | | | | m |indarch, elissavetpol, | april , | | | | |transcaucasia. | | | | | | | | | | | m |cross roads, wilson county, | may , | | | | |n. carolina, u.s.a. | | | | | | | | | | | m |guareÑa, badajoz, spain. | july , | | | | | | | | | | m |bath, s. dakota, u.s.a. | aug. , | , | | | | | | | | | m |pricetown, highland county, | feb. , | | | | |ohio, u.s.a. | | | | | | | | | | | m |bherai, junagadh, kathiawar, | april , | | | | |bombay. | | | | | | | | | | | m |beaver creek, west kootenai | may , | | | | |district, british columbia. | | | | | | | | | | | m |zabrodje, wilna, russia. | sept. , | | | | | | | | | | m |fisher, polk county, | april , | | | | |minnesota, u.s.a. | | | | | | | | | | | m |bori, badnúr, betul district, | may , | , | | | |central provinces, india. | | | | | | | | | | | m |savtschenskoje, kherson, | july , | | | | |russia. | | | | | | | | | | | m |bishunpur (and parjabatpur), | april , | | | | |mirzapur district, north-west | | | | | |provinces, india. | | | | | | | | | | | m |nagy-borovÉ, liptau, hungary. | may , | | | | | | | | | | m |ambapur nagla, sikandra rao | may , | , | | | |tahsil, aligarh district, | | | | | |north-west provinces, india. | | | | | | | | | | | m |madrid, spain. | feb. , | | | | | | | | | | m |ottawa, franklin county, | april , | | | | |kansas, u.s.a. | | | | | | | | | | | m |lesves, namur, belgium. | april , | | | | | | | | | | n |kangra (valley), north | before aug. | | | | |eastern punjab, india. | | | | | | | | | | | n |meuselbach, thuringia, | may , | | | | |germany. | | | | | | | | | | | n |lanÇon, bouches-du-rhône, | june , | | | | |france. | | | | | | | | | | | n |zavid, district zwornik, | aug. , | | | | |bosnia. | | | | | | | | | | | n |higashikoen, fukuoka, | aug. , | | | | |chikuzen, japan. | | | | | | | | | | | n |gambat, khairpur state, sind, | sept. , | , | | | |india. | | | | | | | | | | | n |saline township, sheridan | nov. , (?)| | | | |county, kansas, u.s.a. | | | | | | | | | | | n |zomba, british central | jan. , | , | | | |africa. | | | | | | | | | | | n |bjurbÖle, borgå, finland. | march , | | | | | | | | | | n |allegan, michigan, u.s.a. | july , | | | | | | | | | | n |donga kohrod, bilatpur, | sept. , | | | | |india. | | | | | | | | | | | n |sindhri, thar and parkar | june , | , | | | |district, bombay, india. | | | | | | | | | | | n |andover, oxford county, | aug. , | | | | |maine, u.s.a. | | | | | | | | | | | n |hvittis, Åbo län, finland. | oct. , | | | | | | | | | | n |palÉzieux, lausanne, | nov. , | | | | |switzerland. | | | | | | | | | | | n |mount browne, evelyn county, | july , | | | | |new south wales. | | | | | | | | | | | n |caratash, smyrna, asia minor. | aug. , | | | | | | | | | | n |crumlin, county antrim, | sept. , | , | | | |ireland. | | | | | | | | | | | n |bath furnace, bath county, | nov. , | , | | | |kentucky, u.s.a. | | | | | | | | | | | n |uberaba, minas geraes, | june , | | | | |brazil. | | | | | | | | | | | o |dokÁchi, dacca district, | oct. , | | | | |bengal, india. | | | | | | | | | | | n |shelburne, grey county, | aug. , | | | | |ontario, canada. | | | +----+------+------------------------------+-------------------+---------+ b. fall not recorded. [arranged topographically.] +----+------+------------------------------+-------------------+---------+ |no. |pane. | name of meteorite and | report of find. | weight | | | | place of find. | |in grams.| +----+------+------------------------------+-------------------+---------+ | | | | | | | | o |mainz, hesse, germany. |jahrb. d. ver. für | | | | | |naturk. im nassau, | | | | |described in by | , p. . | | | | |seelheim: it had been turned | | | | | |up by a plough some years | | | | | |before. | | | | | | | | | | | o |oczeretna, lipovitz, kiev, | | | | | |russia. | | | | | | | | | | | |found in the summer of . | | | | | | | | | | | o |assam, india. |proc. asiatic soc. | | | | | |bengal, june, ,| | | | |found in in the refuse |pp. xlvi, lxxvi. | | | | |of the "coal and iron " | | | | | |committee's collections, | | | | | |probably obtained from assam. | | | | | | | | | | | h |goalpara, assam, india. |wien. akad. ber. | , | | | | | , vol. , part| | | | |found among some specimens | , p. . | | | | |obtained from the | | | | | |neighbourhood of goalpara: | | | | | |described by haidinger in | | | | | | . | | | | | | | | | | | o |kota-kota, marimba district, | | | | | |british central africa. | | | | | | | | | | | o |warbreccan, windorah, | | , | | | |diamantina district, | | | | | |queensland. | | | | | | | | | | | o |barratta, deniliquin, new |trans. roy. soc. | , | | | |south wales. |of new south wales,| | | | | | , vol. , | | | | |one person thought he saw it |p. . | | | | |fall in the month of may, | | | | | |about : another reports | | | | | |that he saw the mass lying on | | | | | |the ground in . | | | | | | | | | | | |two other masses were |jour. and proc. | | | | |describedby liversidge in |roy. soc. new south| | | | | . |wales, , vol. | | | | | | , p. . | | | | | | | | | | o |gilgoin, new south wales: |jour. & proc. roy. | , | | | |described by russell in . |soc. new south | | | | | |wales, , vol. | | | | | | , p. . | | | | | | | | | | |a second mass, found later, |jour. & proc. roy. | | | | |was described by liversidge |soc. new south | | | | |in . |wales, , vol. | | | | | | , p. . | | | | | | | | | | o |makariwa, invercargill, new |proc. roy. soc., | | | | |zealand. | , vol. , p. | | | | | | : mineralog. | | | | |found in clay, about - / ft.|magazine, , | | | | |from the surface, in : |vol. , p. . | | | | |described by ulrich and l. f. | | | | | |in - . | | | | | | | | | | | o |tomhannock creek, rensselaer |amer. jour. sc. | | | | |county, new york, u.s.a. | , ser. , vol. | | | | | | , p. : | | | | |found about the year : |ann. d.k.k. naturh.| | | | |described by bailey in : |hofmus. wien, ,| | | | |brezina points out a close |vol. , p. . | | | | |likeness of this stone, and | | | | | |also of "yorktown," to those | | | | | |of amana. | | | | | | | | | | | o |morristown, hamblen county, |amer. jour. sc. | | | | |tennessee, u.s.a. | , ser. ; vol. | | | | | | , p. . | | | | |found in : described by | | | | | |eakins in . | | | | | | | | | | | o |elm creek, admire, lyon |amer. jour. sci. | | | | |county, kansas, u.s.a. | ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |howard in . | | | | | | | | | | | o |waconda, mitchell county, |amer. jour. sc. | | | | |kansas, u.s.a. | , ser. , vol. | | | | | | , p. : trans. | | | | |found in in the grass, |kansas ac. sc. | | | | |upon the slope of a ravine: | , vol. , p. | | | | |described by shepard and by | . | | | | |patrick in . | | | | | | | | | | | o |prairie dog creek, decatur |tschermak's min. | | | | |county, kansas, u.s.a. |und petrog. mitth. | | | | | | - , vol. , p.| | | | |reported and described by | . | | | | |weinschenk in . | | | | | | | | | | | o |long island, phillips county, | _ibid_. | , | | | |kansas, u.s.a. | | | | | | | | | | | |reported and described by | | | | | |weinschenk in . | | | | | | | | | | | o |oakley, logan county, |amer. jour. sc. | , | | | |kansas, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |preston in . | | | | | | | | | | | o |kansada, ness county, | | , | | | |kansas, u.s.a. found in . | | | | | | | | | | | o |ness city, ness county, |amer. jour. sc. | | | | |kansas, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |ward in . | | | | | | | | | | | o |utah, u.s.a. |amer. jour. sc. | | | | | | , ser. , vol. | | | | |found in on the open | , p. . | | | | |prairie between salt lake city| | | | | |city and echo, utah: described| | | | | |by dana and penfield in . | | | | | | | | | | | o |mckinney, collin county, | | | | | |texas, u.s.a. | | | | | | | | | | | o |bluff, miles s. w. of la |amer. jour. sc. | , | | | |grange, fayette county, texas.| , ser. , vol. | | | | | | , p. . | | | | |found about , and | | | | | |described by whitfield and | | | | | |merrill in . | | | | | | | | | | | o |pipe creek, bandera county, |trans. of new york | | | | |texas, u.s.a. |ac. of sc., - ,| | | | | |vol. , p. . | | | | |found in : described by | | | | | |ledoux in - . | | | | | | | | | | | a |estacado, hale county, |amer. jour. sc. | , | | | |texas, u.s.a. | , ser. , vol. | | | | | | , p. . | | | | |found in : described by | | | | | |howard in . | | | | | | | | | | | o |cobija, tocopilla, |proc. rochester ac.| | | | |antofagasta, chili, s. |sci. , vol. , | | | | |america. |p. . | | | | | | | | | | |found in : described by | | | | | |ward in . | | | | | | | | | | | o |the lutschaunig stone, |mineralog. | | | | |atacama, chili. |magazine, , | | | | | |vol. , p. . | | | | | | | | | | o |carcote, atacama, chili, s. |neues jahrb. f. | | | | |america. |min., , vol. ,| | | | | |p. . | | | | |known since : described | | | | | |by sandberger in . | | | | | | | | | | | o |santiago, chili. | | | | | | | | | | | o |minas geraes (?), brazil. |revista do | | | | | |observatorio, rio | | | | |found without label among |de janeiro, . | | | | |specimens which may have been | | | | | |brought from minas geraes: | | | | | |mentioned by derby in . | | | | | | | | | | | o |indio rico, buenos ayres, |anales de la | · | | | |argentina. |sociedad científica| | | | | |argentina, , | | | | |described by kyle in . |vol. , p. . | | +----+------+------------------------------+-------------------+---------+ list of recent additions. (_meteorites for the first time included in the list._) angelas no. mern no. billings no. narraburra no. boogaldi no. rodeo no. canyon city no. santiago no. cobija no. shelburne no. dokÁchi no. tanokami no. el inca no. uberaba no. elm creek no. uwet no. estacado no. warbreccan no. ilimaes no. weaver's mountains no. kangra no. willamette no. kota-kota no. yon[=o]zu no. * * * * * list of british meteorites. of the preceding meteorites the following have fallen within the british isles:-- name. date of fall. . in england--wold cottage december , launton february , aldsworth august , rowton april , middlesbrough march , . in scotland--high possil april , perth may , . in ireland--mooresfort august, adare september , killeter april , dundrum august , crumlin september , one of them, rowton, is a meteoric iron; the rest are meteoric stones. appendix a. * * * * * native iron (of terrestrial origin). (pane m.) +----------------------------------------------+----------------------+ | name of iron and place of find. | report of find. | +----------------------------------------------+----------------------+ |niakornak, jakobshavn district, west |oversigt over det | |greenland. (rink's iron). |koniglike danske | | |vidensk. selsk. forh. | |part of a lump obtained ( - ) by dr. | , p. . | |rink from a greenlander who lived at | | |niakornak: it had been found not far from | | |his home, lying loose on a pebble-strewn | | |plain near the coast. | | | | | | | | |jakobshavn, west greenland (the pfaff-Öberg |geological magazine, | |iron). | , vol. , | | |p. . | |part of a lump given by dr. pfaff | | |of jakobshavn to dr. Öberg in : | | |it was said to have been found in the | | |neighbourhood (perhaps near niakornak). | | | | | | | | |ovifak, disko island, west greenland. |geological magazine, | | | , vol. , | |found by baron n. a. e. nordenskiöld |p. . | |in . | | | | | | | | |new zealand (jackson's bay). |trans. and proc. of | | |new zealand institute,| |found in , and described by skey | , vol. , | |in the same year (awaruite). |p. . | | | | | | | |south america. |bull. of the geol. | | |instit. of the univ. | |found in an old collection; described |of upsala, , | |by högbom in . |vol. , p. . | +----------------------------------------------+----------------------+ appendix b. * * * * * pseudo-meteorites which have been described as meteorites. (in drawers.) aachen, rhenish prussia. braunfels, coblenz. campbell county, tennessee, u.s.a. canaan, connecticut, u.s.a. collina di brianza, milan, italy. concord, new hampshire, u.s.a. gross-kamsdorf, saxony. haywood county, n. carolina, u.s.a. heidelberg, germany. hemalga, desert of tarapaca, s. america. hommoney creek, buncombe county, n. carolina, u.s.a. igast, livland, russia. kamtschatka, asiatic russia. leadhills, lanarkshire, scotland. long creek, jefferson county, new york, u.s.a. magdeburg, prussia. nauheim, giessen, germany. new haven, connecticut, u.s.a. newstead, roxburghshire, scotland. nÖbdenitz, saxon altenburg. richland, s. carolina, u.s.a. rutherfordton, n. carolina, u.s.a. st. augustine's bay, madagascar. scriba, oswego county, new york, u.s.a. south america. sterlitamak, russia. voigtland, saxony. waterloo, new york, u.s.a. list of the casts of meteorites. meteorites are generally represented in collections by mere fragments of the original specimens, which often fail to give any idea of the original size and shape. before division of a specimen a cast of it is sometimes prepared, and a representation of the size and shape is thus preserved. casts of most of the following meteorites are exhibited in the lower parts of the cases:-- _akburpur._ _amana._ assisi. _barranca blanca._ _babb's mill._ barratta. beuste. bingera. _bithur._ boogaldi. braunau. _breitenbach._ buschhof. _bustee._ _butsura._ cabin creek. cachiyuyal. caperr. chandakapur. _charlotte._ chulafinnee. _cronstad._ _crumlin._ daniel's kuil. dolgovoli. donga kohrod. dundrum. _durala._ goalpara. gopalpur. ibbenbühren. _jelica._ _jhung._ _kaee._ _khiragurh._ klein-menow. launton. lick creek. linum. mazapil. _mhow._ _middlesbrough._ mooresfort. _mouza khoorna._ nagy-diwina. nash county. _nedagolla._ _nejed._ _nellore._ nerft. newstead. new zealand. _obernkirchen._ _ogi._ _parnallee._ petersburg. pillistfer. pulsora. _rancho de la pila._ rittersgrün. roebourne. _rowton._ st. denis-westrem. sarepta. _segowlie._ shytal. sindhri. _sitathali._ ski. _udipi._ virba. _warbreccan._ _wittekrantz._ the trustees possess moulds of those meteorites in the preceding list of which the names are printed in italics, and casts may be obtained on payment of the necessary expenses. applications should be made in writing to the formatori, d. brucciani & co., goswell road, london, e.c. index to the meteorites represented in the collection on may , . * * * * * _the names adopted for the meteorites are printed in capitals: the other names are synonyms._ _the numbers correspond with those of the first column of the meteorite list._ no. aachen, (pseudo-meteorite). abert iron (unknown locality), adare, admire, aeriotopos_v._bear creek, agen, agra, agra _v._ khiragurh, agram, aigle _v._ l'aigle, ainsa iron _v._ tucson, akbarpur, akershuus _v._ ski, alais, alatyr, albareto, albuquerque _v._ glorieta mountain, b aldsworth, aleppo, alessandria, alexejevka _v._ bachmut, alexinatz _v._ soko-banja, alfianello, algoma, allahabad _v._ futtehpur, allegan allen county _v._ scottsville, amana, ambapur nagla, andover, angelas, angers, angra dos reis, antifona _v._ collescipoli, apoala, apt, arispe, arlington, arva, asco, asheville, asheville _v._ black mountain, assam, assisi, aubres, auburn, augusta county _v._ staunton, augustinovka, aukoma _v._ pillistfer, aumale, aumiÈres, ausson, authon _v._ lancÉ, babb's mill, bachmut, bacubirito _v._ el ranchito, bahia _v._ bendegÓ river, baird's farm _v._ asheville, baird's plantation _v._ asheville, baldohn, ballinoo, bambuk _v._ senegal river, bancoorah _v._ shalka, bandong, barbotan, barranca blanca, barratta, basti _v._ bustee, bates county _v._ butler, bath, bath furnace, batsura _v._ butsura, beaconsfield _v._ cranbourne, b bear creek, beaver creek, bécasse _v._ la bÉcasse, behar _v._ sherghotty, belaja-zerkov _v._ bjelaja zerkov, belgorod _v._ sevrukovo, bella roca, bendegÓ river, benares _v._ krakhut, berar _v._ chandakapur, beraun _v._ zebrak, berlanguillas, bethany, bethlehem, beuste, bhagur, bherai, bhurtpur _v._ moti-ka-nagla, bialystock, bielokrynitschie, billings, bischtÜbe, bishopville, bishunpur, bissempore _v._ shalka, bitburg, bithur _v._ futtehpur, bjelaja zerkov, bjurbÖle, blaauw-kapel _v._ utrecht, black mountain, blansko, bluff, bocas _v._ hacienda de bocas, bogota _v._ rasgata, bohumilitz, bois de fontaine _v._ charsonville, bokkeveldt _v._ cold bokkeveld, bolson de mapimi _v._ coahuila, a bolson de mapimi _v._ sanchez estate, b bonanza iron _v._ coahuila, a boogaldi, borgo san donino, bori, borkut, brahin, braunau, braunfels (pseudo-meteorite). brazos river, breitenbach, c bremervörde _v._ gnarrenburg, brenham township, bridgewater, bubuowly _v._ supuhee, budetin _v._ nagy-diwina, bückeburg _v._ obernkirchen, bueste _v._ beuste, bugaldi _v._ boogaldi, bunzlau _v._ lissa, burlington, buschhof, bustee, butcher iron _v._ coahuila, a butler, butsura, cabarras county, cabeza de mayo, cabin creek, cacaria, cachiyuyal, caille _v._ la caille, callac _v._ kerilis, cambria _v._ lockport, campbell county, (pseudo-meteorite). campo del cielo _v._ otumpa, campo de pucará _v._ imilac, canaan (pseudo-meteorite). canara _v._ udipi, canellas, caney fork, cangas de onis, caÑon diablo, canton, canyon city, cape girardeau, cape of good hope, caperr, capitan range, caracoles _v._ imilac, caratash, carcoar _v._ cowra, carcote, carleton iron _v._ tucson, carlton, carroll county _v._ eagle station, carthage, caryfort _v._ caney fork, casale _v._ cereseto, casas grandes, casey county, castalia _v._ nash county, castine, catorze _v._ descubridora, central missouri, cereseto, cerro cosina, chail, chandakapur, chandpur, chantonnay, charcas, charkow _v._ kharkov, charleston _v._ jenny's creek, charlotte, charlottetown _v._ cabarras county. charsonville, chartres _v._ charsonville, charwallas, chassigny, chÂteau-renard, cherokee mills _v._ canton, cherson _v._ vavilovka, chesterville, chili, christian county _v._ billings, chulafinnee, chupaderos, cirencester _v._ aldsworth, claiborne, claiborne county _v._ tazewell, clarac _v._ ausson, clarke county _v._ claiborne, claywater stone _v._ vernon county. cleberne county _v._ chulafinnee, clÉguÉrec, cleveland, coahuila, a cobija, cocke county, cold bokkeveld, colfax _v._ ellenboro', collescipoli, collina di brianza (pseudo-meteorite). commune des ormes _v._ les ormes. concepcion, concord (pseudo-meteorite) coneyfork _v._ caney fork, coopertown, copiapo, cosby's creek _v._ cocke county, cosona _v._ siena, cossipore _v._ manbhoom, costa rica _v._ heredia, costilla peak, cowra, cranbourne, crawford county _v._ taney county. cronstad, cross roads, cross timbers _v._ red river, crow creek, crumlin, cuernavaca, cusignano _v._ borgo san donino, cynthiana, czartorya _v._ zaborzika, dacca _v._ shytal, dakota, dalton _v._ whitfield county, dandapur, daniel's kuil, danville, darmstadt, davis strait _v._ melville bay, deal, debreczin _v._ kaba, decatur county _v._ prairie dog creek. deep springs, deesa _v._ copiapo, de kalb county _v._ caney fork, denton county, denver _v._ bear creek, descubridora, dhulia _v._ bhagur, dhurmsala, dickson county _v._ charlotte, disko island _v._ ovifak (telluric). djati-pengilon, dokÁchi, dolgaja wolja _v._ dolgovoli, dolgovoli, doÑa inez, donga kohrod, dooralla _v._ durala, doroninsk, drake creek, duel hill _v._ jewell hill, b dundrum, durala, duruma, dyalpur, eagle station, east tennessee _v._ cleveland, echigo _v._ yon[=o]zu, echo _v._ utah, eichstÄdt, eifel _v._ bitburg, elbogen, elgueras _v._ cangas de onis, el inca, ellenboro', elm creek, elmo _v._ independence county, el ranchito, emmet county _v._ estherville, emmittsburg, ensisheim, epinal, ergheo, erxleben, eschigo _v._ yon[=o]zu, esnandes, estacado, estherville, faha _v._ adare, farmington, fatchpur _v._ futtehpur, favars, fayette county _v._ bluff, fekete _v._ mezÖ-madaras, finmarken, fisher, fish river _v._ great fish river, a floyd, county _v._ indian valley township, fomatlan _v._ tomatlan, forest city _v._ winnebago county, forsyth, forsyth county, fort duncan, fort pierre _v._ nebraska, franceville, frankfort (alabama), frankfort (kentucky), franklin county _v._ frankfort, , fürstenburg _v._ klein-menow, fukutomi, fulton county _v._ rochester, futtehpur, gambat, gargantillo _v._ tomatlan, garz _v._ schellin, gera _v._ pohlitz, ghazeepore _v._ mhow, ghent _v._ st. denis-westrem, ghoordha _v._ moti-ka-nagla, gilgoin, girgenti, glorieta mountain, a, b gnadenfrei, gnarrenburg, goalpara, gopalpur, gran chaco _v._ otumpa, grand rapids, great fish, river _v._ bethany, a great fish, river _v._ cape of good hope, great namaqualand _v._ bethany, greenbrier county, green county _v._ babb's mill, grenade _v._ toulouse, griqualand _v._ daniel's kuil, grosnaja, gross-diwina _v._ nagy-diwina, gross-kamsdorf, (pseudo-meteorite) gross-liebenthal, grÜneberg, guareÑa, guernsey county _v._ new concord, gÜtersloh, guilford county, gurram konda, hacienda de bocas, hainholz, hamblen county _v._ morristown, hamilton county _v._ carlton, hammond township, harrison county, hartford _v._ linn county, hauptmannsdorf _v._ braunau, hawaii _v._ honolulu, hayden creek, haywood county, (pseudo-meteorite). heidelberg (pseudo-meteorite). heinrichsau _v._ grÜneberg, hemalga (pseudo-meteorite). heredia, hessle, hex river mountains, higashikoen, high possil, holland's store, homestead _v._ amana, hommoney creek (pseudo-meteorite). honolulu, horzowitz _v._ zebrak, howard county, hraschina _v._ agram, huesca _v._ roda, hungen, hvittis, ibbenbÜhren, igast (pseudo-meteorite). iglau _v._ stannern, iharaota _v._ lalitpur, ihung _v._ jhung, ilimaË, ilimaes, illinois gulch, imilac, indarch, independence county, indian valley township, indio rico, iowa _v._ amana, iquique _v._ el inca, iron creek, irwin-ainsa iron _v._ tucson, itapicuru-mirim, ivanpah, jackson county, jakobshavn (telluric). jamaica _v._ lucky hill, jamestown, jamkheir, janacera pass _v._ vaca muerta, japan _v._ ogi, jarquera _v._ vaca muerta, jasly _v._ bialystock, jelica, jenny's creek, jewell hill, jharaota _v._ lalitpur, jhung, jigalowka _v._ kharkov, jodzie, joel iron, johanngeorgenstadt _v._ steinbach, a jonzac, juchnow _v._ timochin, judesegeri, juncal, juvinas, kaande _v._ oesel, kaba, kadonah _v._ agra, kaee, kahangarai, kakangarai _v._ kahangarai, kakowa, kalambi, kamtschatka (pseudo-meteorite). kangra, kansada, karakol, karand _v._ veramin, karlsburg _v._ ohaba, kathiawar _v._ bherai, kendall county, kenton county, kerilis, kernouvé _v._ clÉguÉrec, kesen, khairpur, kharkov, kheragur _v._ khiragurh, khetri, khiragurh, kikino, kiowa county _v._ brenham township, killeter, klein-menow, klein-wenden, knasta _v._ bialystock, knoxville _v._ tazewell, knyahinya, kodaikanal, köstritz _v._ pohlitz, kokomo _v._ howard county, kokstad, kota-kota, koursk _v._ sevrukovo, krÄhenberg, krakhut, krasnoi-ugol, krasnojarsk _v._ pallas iron, krasnoslobodsk _v._ alatyr, krawin _v._ tabor, kuleschovka, kusiali, la baffe _v._ epinal, la bÉcasse, laborel, la caille, lagrange, l'aigle, laissac _v._ favars, lalitpur, lancÉ, lanÇon, langenpiernitz _v._ stannern, langres _v._ chassigny, la primitiva, lasdany _v._ lixna, launton, laurens county, la vivionnère _v._ le teilleul, leadhills (pseudo-meteorite). lebedin _v._ kharkov, lÉnÁrto, lerici, les ormes, lesves, le teilleul, lexington county, lexington county _v._ ruff's mountain, libonnez _v._ juvinas, liboschitz _v._ plescowitz, lick creek, lime creek _v._ claiborne, limerick _v._ adare, linn county, linnville mountain, linum, lion river _v._ bethany, b liponnas _v._ luponnas, lissa, little piney, livingston county _v._ smithland, lixna, ljungby _v._ lundsgÅrd, llano del inca, lockport, locust grove, lodran, long creek (pseudo-meteorite). long island, lontolax _v._ luotolaks, losttown, louisiana _v._ red river, louvain _v._ tourinnes-la-grosse, lucÉ, lucky hill, luis lopez, lumpkin _v._ stewart county, lundsgÅrd, luotolaks, luponnas, lutschaunig stone, macao, macayo _v._ macao, macedonia _v._ seres, macerata _v._ monte milone, macon county _v._ auburn, madagascar _v._ st. augustine's bay (pseudo-meteorite). maddur taluk _v._ muddoor, madioen _v._ ngawi, madoc, madrid, mael pestivien _v._ kerilis, maêmê _v._ oshima, mÄssing, magdalena _v._ luis lopez, magdeburg (pseudo-meteorite). magdeburg _v._ erxleben, magura _v._ arva, mainz, makariwa, mánbazar pargama _v._ manbhoom, manbhoom, manegaum, mantos blancos _v._ mount hicks, marimba district _v._ kota-kota, marion _v._ linn county, marjalahti, marmande, marmoros _v._ borkut, marshall county, mart, maryland _v._ nanjemoy, mascombes, mau _v._ mhow, mauerkirchen, mauléon _v._ sauguis, mazapil, mckinney, medwedewa _v._ pallas iron, mejillones _v._ vaca muerta, melbourne _v._ cranbourne, melville bay, menow _v._ klein-menow, merceditas, mern, meuselbach, mexico _v._ pampanga, mezÖ-madaras, mhow, middlesbrough, midt-vaage _v._ tysnes, mighei _v._ migheja, migheja, mikenskoi _v._ grosnaja, miljana _v._ milena, milena, milwaukee _v._ trenton, minas geraes, misshof _v._ baldohn, missouri _v._ south-east missouri, misteca _v._ yanhuitlan, mocs, moctezuma, modena _v._ albareto, molina, monroe _v._ cabarras county, montauban _v._ orgueil, monte milone, montignac _v._ marmande, montlivault, montréjean _v._ ausson, mooltan _v._ lodran, mooranoppin, mooresfort, moradabad, morbihan _v._ clÉguÉrec, mordvinovka _v._ pavlograd, mornans, morristown, morro do rocio _v._ santa catharina. moteeka nugla _v._ moti-ka-nagla, moti-ka-nagla, mount browne, mount dyrring, mount hicks, mount joy, mount stirling, mount zomba _v._ zomba, mouza khoorna _v._ supuhee, muddoor, mukerop _v._ bethany, d mungindi, murcia _v._ cabeza de mayo, murcia _v._ molina, murfreesboro', murphy, muskingum county _v._ new concord. nagaria, nagaya, nagy-borovÉ, nagy-diwina, nagy-vÁzsony, nammianthal, nanjemoy, napoléonsville _v._ clÉguÉrec, narraburra, nash county, nashville _v._ drake creek, nauheim (pseudo-meteorite). nawapali, nebraska, nedagolla, nejed, nellore, nelson county, nenntmannsdorf, nerft, ness city, ness county _v._ kansada, ness county _v._ ness city, netschaëvo _v._ tula, newberry _v._ ruff's mountain, new concord, new haven (pseudo-meteorite). newstead (pseudo-meteorite). newton county _v._ taney county, new zealand (telluric). ngawi, n'goureyma, niagara, niakornak (telluric). nidigullam _v._ nedagolla, nobleborough, nochtuisk, nocoleche, nÖbdenitz (pseudo-meteorite). north inch of perth _v._ perth. novo-urei _v._ alatyr, nulles, nurrah _v._ sitathali, oakley, oaxaca _v._ yanhuitlan, obernkirchen, ocatitlan _v._ toluca, oczeretna, oesel, oficina angelas _v._ angelas, ogi, ohaba, okniny, oktibbeha county, oldham county _v._ lagrange, orange river, orgueil, orléans _v._ charsonville, ormes _v._ les ormes, ornans, oroville, orvinio, oscuro mountain, oshima, oswego county _v._ scriba (pseudo-meteorite). otsego county _v._ burlington, ottawa, ottiglio _v._ cereseto, otumpa, oude _v._ kaee, ovifak (telluric). oynchimura _v._ oshima, pacula, palÉzieux, pallas iron, pampa de tamarugal _v._ el inca. pampanga, pan de azucar, parma _v._ borgo san donino, parnallee, pavlodar, pavlograd, pavlovka, pegu, penkarring rock _v._ youndegin, pennyman's siding _v._ middlesbrough. perth, petersburg, petropavlovsk, pfaff-Öberg _v._ jakobshavn (telluric). philippine islands _v._ pampanga, phillips county _v._ long island, pillistfer, pine bluff _v._ little piney, pipe creek, pirgunje, pirthalla, pittsburg, plescowitz, ploschkowitz _v._ plescowitz, plymouth, pohlitz, pokhra, politz _v._ pohlitz, poltawa _v._ kuleschovka, poltawa of partsch _v._ slobodka, powder mill creek, prachin _v._ bohumilitz, prairie dog creek, prambanan, praskoles _v._ zebrak, pricetown, pulaski _v._ little piney, pulsora, pultusk, puquios, pusinsko selo _v._ milena, putnam county, quenggouk _v._ pegu, quinÇay, raepur _v._ sitathali, rakovka, ranchito _v._ el ranchito, rancho de la pila, rasgata, red river, reed city, reichstadt _v._ plescowitz, renazzo, rhine valley _v._ rhine villa, rhine villa, richland (pseudo-meteorite). richmond, rink's iron _v._ niakornak (telluric). rittersgrÜn, b robertson county _v._ coopertown, rochester, rockwood _v._ powder mill creek, roda, rodeo, roebourne, roki[)c]ky _v._ brahin, roquefort _v._ barbotan, rosario, ross's iron _v._ melville bay, rowton, roxburghshire, _v._ newstead (pseudo-meteorite). ruff's mountain, russel gulch, rutherford county _v._ murfreesboro', rutherfordton, (pseudo-meteorite). rutlam _v._ pulsora, saboryzy _v._ zaborzika, sacramento mountains, saharanpur _v._ akbarpur, st. augustine's bay (pseudo-meteorite). st. caprais-de-quinsac, st. denis-westrem, st. genevieve county, st. julien _v._ alessandria, st. mesmin, st. nicholas _v._ mÄssing, saintonge _v._ jonzac, saline township, salles, saltillo _v._ sanchez estate, b salt lake city _v._ utah, salt river, sáluká _v._ shalka, san angelo, san bernardino county _v._ ivanpah. sanchez estate, b san cristobal, san francisco del mezquital, san francisco pass _v._ barranca blanca, san josé _v._ heredia, san pedro _v._ imilac, santa barbara, santa catharina, santa rosa, santa rosa _v._ coahuila, a santa rosa _v._ sanchez estate, b santiago, sÃo juliÃo de moreira, saonlod _v._ khetri, sarbanovac _v._ soko-banja, sarepta, saskatchewan _v._ iron creek, sauguis, saurette _v._ apt, savtschenskoje, scheikahr stattan _v._ buschhof, schellin, schie _v._ ski, schobergrund _v._ gnadenfrei, schÖnenberg, schwetz, scottsville, scriba (pseudo-meteorite). searsmont, seelÄsgen, segowlie, sena, seneca river (or falls), senegal river, senhadja _v._ aumale, seres, serrania de varas, sevier county _v._ cocke county, sevrukovo, shahpur _v._ futtehpur, shaital _v._ shytal, shalka, shelburne, sherghotty, shingle springs, shytal, sidowra _v._ supuhee, siena, sierra blanca, sierra de chaco _v._ vaca muerta, sierra de deesa _v._ copiapo, sierra de la ternera, signet iron _v._ tucson, sikkensaare _v._ tennasilm, silver crown _v._ crow creek, sindhri, siratik _v._ senegal river, sitathali, ski, slavetic, slobodka, smithland, smith's mountain, smithsonian iron (unknown locality). smithville, socrakarta _v._ prambanan, soko-banja, south america (telluric). south arcot _v._ nammianthal, south canara _v._ udipi, south-east missouri, sowallick mountain _v._ melville bay. springbok river _v._ bethany, d ssyromolotovo, staartje _v._ uden, stÄlldalen, stannern, staunton, stavropol, steinbach, a sterlitamak (pseudo-meteorite). stewart county, stinking creek _v._ campbell county (pseudo-meteorite). stutsman county _v._ jamestown, summit, supuhee, surakarta _v._ prambanan, surprise springs, szadany _v._ zsadÁny, szlanicza _v._ arva, tabarz, tabor, tabory, tadjera, taiga _v._ toubil river, takenouchi, tamarugal _v._ el inca, taney county, tanokami, tarapaca, tarapaca desert _v._ hemalga (pseudo-meteorite). tazewell, teilleul _v._ le teilleul, tennasilm, terni _v._ collescipoli, texas _v._ red river, thunda, thurlow, tieschitz, timochin, tipperary _v._ mooresfort, tjabÉ, tocavita _v._ santa rosa, b toluca, tomatlan, tombigbee river, tomhannock creek, tonganoxie, toubil river, toulouse, tourinnes-la-grosse, trenton, trenzano, triguères _v._ chÂteau-renard, tucson, tucuman _v._ otumpa, tula, turuma _v._ duruma, tysnes, uberaba, uden, udipi, umballa, umjhiawar _v._ sherghotty, union county, utah, utrecht, uwet, vaca muerta, varas _v._ serrania de varas, vavilovka, venagas _v._ descubridora, veramin, veresegyhaza _v._ ohaba, verkhne-dnieprovsk, verkhne-udinsk, vernon county, victoria west, virba, voigtland (pseudo-meteorite). vouillÉ, waconda, waldron ridge, walker county, warbreccan, warrenton, washington _v._ farmington, waterloo (pseudo-meteorite). wayne county, weaver's mountains, welland, werchne _v._ verkhne wessely, west liberty _v._ amana, weston, whitfield county, wichita county _v._ brazos river, wild _v._ bethany, c willamette, winnebago county, witim _v._ verkhne-udinsk, wittmess _v._ eichstÄdt, wÖhler's iron (unknown locality), wold cottage, xiquipilco _v._ toluca, yanhuitlan, yarra yarra river _v._ cranbourne, c yatur _v._ nellore, yenshigahara _v._ oshima, yodzé _v._ jodzie, yon[=o]zu, yorktown _v._ tomhannock creek, youndegin, zaborzika, zabrodje, zacatecas, zavid, zebrak, ziquipilco _v._ toluca, znorow _v._ wessely, zomba, zsadÁny, the end. british museum (natural history) cromwell road, london, s.w. * * * * * guide books. a general guide to the british museum (natural history). woodcuts, plans, and views of the building. vo. d. zoological department. guide to the galleries of mammals (other than ungulates). woodcuts and plans. vo. d. ---- great game animals (ungulata). illustrations. vo. s. ---- horse family (equidæ). illustrations. vo. s. ---- domesticated animals (other than horses). illustrations. vo. d. ---- gallery of birds. plates and woodcuts. royal vo. s. d. ---- ---- part i. general series. royal vo. d. ---- ---- part ii. nesting series of british birds. plates. royal vo. d. ---- gallery of reptilia and amphibia. illustrations. vo. d. ---- gallery of fishes. illustrations. vo. s. ---- exhibited series of insects. illustrations. vo. s. ---- shell and star-fish galleries. woodcuts and plan. vo. d. ---- coral gallery (protozoa, porifera or sponges, hydrozoa, and anthozoa). illustrations and plan. vo. s. [_guides to other sections are in preparation._] geological department. a guide to the fossil mammals and birds. plates and woodcuts. vo. d. ---- fossil reptiles and fishes. plates and woodcuts. vo. d. ---- fossil invertebrate animals. plates and text-figures. vo. s. ---- elephants (recent and fossil). text-figures. vo. d. mineral department. a guide to the mineral gallery. plan. vo. d. the student's index to the collection of minerals. plan. vo. d. an introduction to the study of minerals, with a guide to the mineral gallery. woodcuts. plan. vo. d. ---- study of rocks. plan. vo. d. ---- study of meteorites, with a list of the meteorites represented in the collection. plan. vo. d. botanical department. list of british seed-plants and ferns. vo. d. guide to sowerby's models of british fungi. woodcuts. vo. d. guide to the british mycetozoa. woodcuts. vo. d. special guides. no. . guide to an exhibition of old natural history books. vo. d. no. . books and portraits illustrating the history of plant classification. plates. vo. d. no. . memorials of linnæus. plates. vo. d. _the guide-books can be obtained only at the natural history museum. written communications respecting them should be addressed to_ the director. * * * * * london: printed by william clowes and sons, limited, duke street, stamford street, s.e., and great windmill street, w. british museum (natural history). * * * * * days and hours of admission. * * * * * the exhibition galleries are open to the public, free, every week-day, in january, from a.m. till p.m. february, st to th, from a.m. till . p.m. february, th to end, from a.m. till p.m. march, from a.m. till . p.m. april to august, from a.m. till p.m. september, from a.m. till . p.m. october, from a.m. till p.m. november and december, from a.m. till p.m. also, from may st to the middle of july, on mondays and saturdays only, till p.m., and from the middle of july to the end of august, on mondays and saturdays only, till p.m. the museum is also open on sunday afternoons throughout the year. the museum is closed on good friday and christmas day. by order of the trustees. london: printed by william clowes and sons, limited, duke street, stamford street, s.e., and great windmill street, w. transcriber's notes: the italics used for pane numbers in side notes and the catalogue have not been marked with underline characters to improve the readability of the text. the printed edition also contains some diacriticals and subscripts that are represented in this e-text as follows; . a macron is represented by an =, e.g. [=o] . a breve is represented by a ), e.g., [)c] . [oe] represents an oe ligature . a subscript in a chemical formula is surrounded by {}, e.g. cu{ }sb the printed edition had the adopted names for meteorites in the various lists in bold, this e-text has instead reproduced them in upper case. in the printed edition where a numbered section continues onto a new page the sidenotes from the previous page are sometimes repeated at the top of the new page. this e-text instead only repeats the sidenote if a new numbered section without a sidenote follows. in one of the list of meteorites the typesetter occasionally used large curly brackets (e.g no. , , , , , , , ) to collect together the names of multiple falls of meteorites and the location. instead this e-text has the location following the adopted name for the meteorite, with the multiple falls listed below without curly brackets. page original text replaced with all ditto marks repeated the actual text - the various lists of standardised by placing a meteorites were inconsistent full stop at the end of every in the use of a full stop at place of fall. the end of the place of fall. , , , batsúra batsura haywood county, haywood county, pseudo-meteorite) (pseudo-meteorite) montauban v orgueil, montauban v. orgueil, senhadja v aumale, senhadja v. aumale, werchne v. verkhne werchne v. verkhne at the internet archive. transcriber notes text emphasis displayed as _italics_ and =bold=. whole and fractional parts displayed as - / . the international scientific series volume lxi the international scientific series. ------------------- =each book complete in one volume, mo, and bound in cloth.= ------------------- . forms of water: a familiar exposition of the origin and phenomena of glaciers. by j. tyndall, ll. d., f. r. s. with illustrations. $ . . . physics and politics; 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(adapted from ward.)] the international scientific series the geological history of plants by sir j. william dawson c. m. g., ll. d., f. r. s., &c. _with illustrations_ new york appleton and company copyright, , by d. appleton and company. preface. the object of this work is to give, in a connected form, a summary of the development of the vegetable kingdom in geological time. to the geologist and botanist the subject is one of importance with reference to their special pursuits, and one on which it has not been easy to find any convenient manual of information. it is hoped that its treatment in the present volume will also be found sufficiently simple and popular to be attractive to the general reader. in a work of so limited dimensions, detailed descriptions cannot be given, except occasionally by way of illustration; but references to authorities will be made in foot-notes, and certain details, which may be useful to collectors and students, will be placed in notes appended to the chapters, so as not to encumber the text. the illustrations of this work are for the most part original; but some of them have previously appeared in special papers of the author. j. w. d. _february, ._ contents. page chapter i. preliminary ideas of geological chronology and of the classification of plants chapter ii. vegetation of the laurentian and early paleozoic--questions as to algæ chapter iii. the erian or devonian forests--origin of petroleum--the age of acrogens and gymnosperms chapter iv. the carboniferous flora--culmination of the acrogens--formation of coal chapter v. the flora of the early mesozoic--reign of pines and cycads chapter vi. the reign of angiosperms in the later cretaceous and early tertiary or kainozoic chapter vii. plants from the tertiary to the modern period chapter viii. general laws of origin and migrations of plants--relations of recent and fossil floras appendix. i. comparative view of paleozoic floras ii. heer's latest statements on the greenland flora iii. mineralisation of fossil plants iv. general works on palæobotany list of illustrations. page table of chronology of plants (frontispiece.) protannularia harknessii nematophyton logani (three figures) , trail of king-crab trail of carboniferous crustacean rusichnites palæophycus astropolithon carboniferous rill-mark cast of shrinkage cracks cone-in-cone buthotrephis silurian vegetation erian plants protosalvinia ptilophyton (two figures) , psilophyton (two figures) , sphenophyllum lepidodendron various ferns , archæopteris caulopteris megalopteris calamites asterophyllites dadoxylon cordaites erian fruits foliage from the coal-formation sigillariæ (five figures) - stigmariæ (two figures) vegetable tissues coals and erect trees (two figures) , lepidodendron lepidophloios asterophyllites, &c. calamites (five figures) - ferns of the coal-formation (six figures) - noeggerathia dispar cordaites fruits of cordaites, &c. conifers of the coal-formation (four species) trigonocarpum sternbergia walchia imbricatula foliage of the jurassic period podozamites salisburia sequoia populus primæva stercalia and laurophyllum vegetation of the cretaceous period platanus protophyllum magnolia liriodendron (two figures) brasenia gaylussaccia resinosa populus balsamifera fucus the geological history of plants. chapter i. preliminary ideas of geological chronology and of the classification of plants. the knowledge of fossil plants and of the history of the vegetable kingdom has, until recently, been so fragmentary that it seemed hopeless to attempt a detailed treatment of the subject of this little book. our stores of knowledge have, however, been rapidly accumulating in recent years, and we have now arrived at a stage when every new discovery serves to render useful and intelligible a vast number of facts previously fragmentary and of uncertain import. the writer of this work, born in a district rich in fossil plants, began to collect and work at these as a boy, in connection with botanical and geological pursuits. he has thus been engaged in the study of fossil plants for nearly half a century, and, while he has published much on the subject, has endeavoured carefully to keep within the sphere of ascertained facts, and has made it a specialty to collect, as far as possible, what has been published by others. he has also enjoyed opportunities of correspondence or personal intercourse with most of the more eminent workers in the subject. now, in the evening of his days, he thinks it right to endeavour to place before the world a summary of facts and of his own matured conclusions--feeling, however, that nothing can be final in this matter; and that he can only hope to sketch the present aspect of the subject, and to point the way to new developments, which must go on long after he shall have passed away. the subject is one which has the disadvantage of presupposing some knowledge of the geological history of the earth, and of the classification and structures of modern plants; and in order that all who may please to read the following pages may be placed, as nearly as possible, on the same level, this introductory chapter will be devoted to a short statement of the general facts of geological chronology, and of the natural divisions of the vegetable kingdom in their relations to that chronology. the crust of the earth, as we somewhat modestly term that portion of its outer shell which is open to our observation, consists of many beds of rock superimposed on each other, and which must have been deposited successively, beginning with the lowest. this is proved by the structure of the beds themselves, by the markings on their surfaces, and by the remains of animals and plants which they contain; all these appearances indicating that each successive bed must have been the surface before it was covered by the next. as these beds of rock were mostly formed under water, and of material derived from the waste of land, they are not universal, but occur in those places where there were extensive areas of water receiving detritus from the land. further, as the distinction of land and water arises primarily from the shrinkage of the mass of the earth, and from the consequent collapse of the crust in some places and ridging of it up in others, it follows that there have, from the earliest geological periods, been deep ocean-basins, ridges of elevated land, and broad plateaus intervening between the ridges, and which were at some times under water, and at other times land, with many intermediate phases. the settlement and crumpling of the crust were not continuous, but took place at intervals; and each such settlement produced not only a ridging up along certain lines, but also an emergence of the plains or plateaus. thus at all times there have been ridges of folded rock constituting mountain-ranges, flat expansions of continental plateau, sometimes dry and sometimes submerged, and deep ocean-basins, never except in some of their shallower portions elevated into land. by the study of the successive beds, more especially of those deposited in the times of continental submergence, we obtain a table of geological chronology which expresses the several stages of the formation of the earth's crust, from that early time when a solid shell first formed on our nascent planet to the present day. by collecting the fossil remains embedded in the several layers and placing these in chronological order, we obtain in like manner histories of animal and plant life parallel to the physical changes indicated by the beds themselves. the facts as to the sequence we obtain from the study of exposures in cliffs, cuttings, quarries, and mines; and by correlating these local sections in a great number of places, we obtain our general table of succession; though it is to be observed that in some single exposures or series of exposures, like those in the great canons of colorado, or on the coasts of great britain, we can often in one locality see nearly the whole sequence of beds. let us observe here also that, though we can trace these series of deposits over the whole of the surfaces of the continents, yet if the series could be seen in one spot, say in one shaft sunk through the whole thickness of the earth's crust, this would be sufficient for our purpose, so far as the history of life is concerned. the evidence is similar to that obtained by schliemann on the site of troy, where, in digging through successive layers of _débris_, he found the objects deposited by successive occupants of the site, from the time of the roman empire back to the earliest tribes, whose flint weapons and the ashes of their fires rest on the original surface of the ground. let us now tabulate the whole geological succession with the history of animals and plants associated with it: animals. systems of formations. plants. age of man and mammalia. kainozoic. { modern, { pleistocene, angiosperms and { pliocene, palms dominant. { miocene, { eocene. age of reptiles. mesozoic. { cretaceous, cycads and pines { jurassic, dominant. { triassic. age of amphibians and fishes. age of invertebrates. palæozoic. { permian, acrogens and { carboniferous, gymnosperms { erian, dominant. { silurian, { ordovician, { cambrian, { huronian (upper). age of protozoa. eozoic. { huronian (lower), protogens and algæ. { upper laurentian, { middle laurentian, { lower laurentian. it will be observed, since only the latest of the systems of formations in this table belongs to the period of human history, that the whole lapse of time embraced in the table must be enormous. if we suppose the modern period to have continued for say ten thousand years, and each of the others to have been equal to it, we shall require two hundred thousand years for the whole. there is, however, reason to believe, from the great thickness of the formations and the slowness of the deposition of many of them in the older systems, that they must have required vastly greater time. taking these criteria into account, it has been estimated that the time-ratios for the first three great ages may be as one for the kainozoic to three for the mesozoic and twelve for the palæozoic, with as much for the eozoic as for the palæozoic. this is dana's estimate. another, by hull and houghton, gives the following ratios: azoic, · per cent.; palæozoic, · per cent.; mesozoic and kainozoic, · per cent. it is further held that the modern period is much shorter than the other periods of the kainozoic, so that our geological table may have to be measured by millions of years instead of thousands. we cannot, however, attach any certain and definite value in years to geological time, but must content ourselves with the general statement that it has been vastly long in comparison to that covered by human history. bearing in mind this great duration of geological time, and the fact that it probably extends from a period when the earth was intensely heated, its crust thin, and its continents as yet unformed, it will be evident that the conditions of life in the earlier geologic periods may have been very different from those which obtained later. when we further take into account the vicissitudes of land and water which have occurred, we shall see that such changes must have produced very great differences of climate. the warm equatorial waters have in all periods, as superficial oceanic currents, been main agents in the diffusion of heat over the surface of the earth, and their distribution to north and south must have been determined mainly by the extent and direction of land, though it may also have been modified by the changes in the astronomical relations and period of the earth, and the form of its orbit.[a] we know by the evidence of fossil plants that changes of this kind have occurred so great as, on the one hand, to permit the plants of warm temperate regions to exist within the arctic circle; and, on the other, to drive these plants into the tropics and to replace them by arctic forms. it is evident also that in those periods when the continental areas were largely submerged, there might be an excessive amount of moisture in the atmosphere, greatly modifying the climate, in so far as plants are concerned. [a] croll, "climate and time." let us now consider the history of the vegetable kingdom as indicated in the few notes in the right-hand column of the table. the most general subdivision of plants is into the two great series of cryptogams, or those which have no manifest flowers, and produce minute spores instead of seeds; and phænogams, or those which possess flowers and produce seeds containing an embryo of the future plant. the cryptogams may be subdivided into the following three groups: . _thallogens_, cellular plants not distinctly distinguishable into stem and leaf. these are the fungi, the lichens, and the algæ, or sea-weeds. . _anogens_, having stem and foliage, but wholly cellular. these are the mosses and liverworts. . acrogens, which have long tubular fibres as well as cells in their composition, and thus have the capacity of attaining a more considerable magnitude. these are the ferns (_filices_), the mare's-tails (_equisetaceæ_), and the club-mosses (_lycopodiaceæ_), and a curious little group of aquatic plants called rhizocarps (_rhizocarpeæ_). the phænogams are all vascular, but they differ much in the simplicity or complexity of their flowers or seeds. on this ground they admit of a twofold division: . _gymnosperms_, or those which bear naked seeds not enclosed in fruits. they are the pines and their allies, and the cycads. . _angiosperms_, which produce true fruits enclosing the seeds. in this group there are two well-marked subdivisions differing in the structure of the seed and stem. they are the _endogens_, or inside growers, with seeds having one seed-leaf only, as the grasses and the palms; and the _exogens_, having outside-growing woody stems, and seeds with two seed-leaves. most of the ordinary forest-trees of temperate climates belong to this group. on referring to the geological table, it will be seen that there is a certain rough correspondence between the order of rank of plants and the order of their appearance in time. the oldest plants that we certainly know are algæ, and with these there are plants apparently with the structures of thallophytes but the habit of trees, and which, for want of a better name, i may call _protogens_. plants akin to the rhizocarps also appear very early. next in order we find forests in which gigantic ferns and lycopods and mare's-tails predominate, and are associated with pines. succeeding these we have a reign of gymnosperms, and in the later formations we find the higher phænogams dominant. thus there is an advance in elevation and complexity along with the advance in geological time, but connected with the remarkable fact that in earlier times low groups attain to an elevation unexampled in later times, when their places are occupied with plants of higher type. it is this historical development that we have to trace in the following pages, and it will be the most simple and at the same time the most instructive method to consider it in the order of time. chapter ii. vegetation of the laurentian and early palÆozoic--questions as to algÆ. oldest of all the formations known to geologists, and representing perhaps the earliest rocks produced after our earth had ceased to be a molten mass, are the hard, crystalline, and much-contorted rocks named by the late sir w. e. logan laurentian, and which are largely developed in the northern parts of north america and europe, and in many other regions. so numerous and extensive, indeed, are the exposures of these rocks, that we have good reason to believe that they underlie all the other formations of our continents, and are even world-wide in their distribution. in the lower part of this great system of rocks which, in some places at least, is thirty thousand feet in thickness, we find no traces of the existence of any living thing on the earth. but, in the middle portion of the laurentian, rocks are found which indicate that there were already land and water, and that the waters and possibly the land were already tenanted by living beings. the great beds of limestone which exist in this part of the system furnish one indication of this. in the later geological formations the limestones are mostly organic--that is, they consist of accumulated remains of shells, corals, and other hard parts of marine animals, which are composed of calcium carbonate, which the animals obtain directly from their food, and indirectly from the calcareous matter dissolved in the sea-water. in like manner great beds of iron-ore exist in the laurentian; but in later formations the determining cause of the accumulation of such beds is the partial deoxidation and solution of the peroxide of iron by the agency of organic matter. besides this, certain forms known as _eozoon canadense_ have been recognised in the laurentian limestones, which indicate the presence at least of one of the lower types of marine animals. where animal life is, we may fairly infer the existence of vegetable life as well, since the plant is the only producer of food for the animal. but we are not left merely to this inference. great quantities of carbon or charcoal in the form of the substance known as graphite or plumbago exist in the laurentian. now, in more recent formations we have deposits of coal and bituminous matter, and we know that these have arisen from the accumulation and slow putrefaction of masses of vegetable matter. further, in places where igneous action has affected the beds, we find that ordinary coal has been changed into anthracite and graphite, that bituminous shales have been converted into graphitic shales, and that cracks filled with soft bituminous matter have ultimately become changed into veins of graphite. when, therefore, we find in the laurentian thick beds of graphite and beds of limestone charged with detached grains and crystals of this substance, and graphitic gneisses and schists and veins of graphite traversing the beds, we recognise the same phenomena that are apparent in later formations containing vegetable _débris_. the carbon thus occurring in the laurentian is not to be regarded as exceptional or rare, but is widely distributed and of large amount. in canada more especially the deposits are very considerable. the graphite of the laurentian of canada occurs both in beds and in veins, and in such a manner as to show that its origin and deposition are contemporaneous with those of the containing rock. sir william logan states[b] that "the deposits of plumbago generally occur in the limestones or in their immediate vicinity, and granular varieties of the rock often contain large crystalline plates of plumbago. at other times this mineral is so finely disseminated as to give a bluish-grey colour to the limestone, and the distribution of bands thus coloured seems to mark the stratification of the rock." he further states: "the plumbago is not confined to the limestones; large crystalline scales of it are occasionally disseminated in pyroxene rock, and sometimes in quartzite and in feldspathic rocks, or even in magnetic oxide of iron." in addition to these bedded forms, there are also true veins in which graphite occurs associated with calcite, quartz, orthoclase, or pyroxene, and either in disseminated scales, in detached masses, or in bands or layers "separated from each other and from the wall-rock by feldspar, pyroxene, and quartz." dr. hunt also mentions the occurrence of finely granular varieties, and of that peculiarly waved and corrugated variety simulating fossil wood, though really a mere form of laminated structure, which also occurs at warrensburg, new york, and at the marinski mine in siberia. many of the veins are not true fissures, but rather constitute a network of shrinkage cracks or segregation veins traversing in countless numbers the containing rock, and most irregular in their dimensions, so that they often resemble strings of nodular masses. it is most probable that the graphite of the veins was originally introduced as a liquid or plastic hydrocarbon; but in whatever way introduced, the character of the veins indicates that in the case of the greater number of them the carbonaceous material must have been derived from the bedded rocks traversed by these veins, to which it bears the same relation with the veins of bitumen found in the bituminous shales of the carboniferous and silurian rocks. nor can there be any doubt that the graphite found in the beds has been deposited along with the calcareous matter or muddy and sandy sediment of which these beds were originally composed.[c] [b] "geology of canada," . [c] paper by the author on laurentian graphite, "journal of london geological society," . the quantity of graphite in the lower laurentian series is enormous. some years ago, in the township of buckingham, on the ottawa river, i examined a band of limestone believed to be a continuation of that described by sir w. e. logan as the green lake limestone. it was estimated to amount, with some thin interstratified bands of gneiss, to a thickness of six hundred feet or more, and was found to be filled with disseminated crystals of graphite and veins of the mineral to such an extent as to constitute in some places one-fourth of the whole; and, making every allowance for the poorer portions, this band cannot contain in all a less vertical thickness of pure graphite than from twenty to thirty feet. in the adjoining township of lochaber sir w. e. logan notices a band from twenty-five to thirty feet thick, reticulated with graphite veins to such an extent as to be mined with profit for the mineral. at another place in the same district a bed of graphite from ten to twelve feet thick, and yielding per cent, of the pure material, is worked. as it appears in the excavation made by the quarrymen, it resembled a bed of coal; and a block from this bed, about four feet thick, was a prominent object in the canadian department of the colonial exhibition of . when it is considered that graphite occurs in similar abundance at several other horizons, in beds of limestone which have been ascertained by sir w. e. logan to have an aggregate thickness of thirty-five hundred feet, it is scarcely an exaggeration to maintain that the quantity of carbon in the laurentian is equal to that in similar areas of the carboniferous system. it is also to be observed that an immense area in canada appears to be occupied by these graphitic and _eozoon_ limestones, and that rich graphitic deposits exist in the continuation of this system in the state of new york, while in rocks believed to be of this age near st. john, new brunswick, there is a very thick bed of graphitic limestone, and associated with it three regular beds of graphite, having an aggregate thickness of about five feet.[d] [d] matthew in "quarterly journal of the geological society," vol. xxi., p. . "acadian geology," p. . it may fairly be assumed that in the present world, and in those geological periods with whose organic remains we are more familiar than with those of the laurentian, there is no other source of unoxidized carbon in rocks than that furnished by organic matter, and that this has obtained its carbon in all cases, in the first instance, from the deoxidation of carbonic acid by living plants. no other source of carbon can, i believe, be imagined in the laurentian period. we may, however, suppose either that the graphitic matter of the laurentian has been accumulated in beds like those of coal, or that it has consisted of diffused bituminous matter similar to that in more modern bituminous shales and bituminous and oil-bearing limestones. the beds of graphite near st. john, some of those in the gneiss at ticonderoga in new york, and at lochaber and buckingham, and elsewhere in canada, are so pure and regular that one might fairly compare them with the graphitic coal of rhode island. these instances, however, are exceptional, and the greater part of the disseminated and vein graphite might rather be likened in its mode of occurrence to the bituminous matter in bituminous shales and limestones. we may compare the disseminated graphite to that which we find in those districts of canada in which silurian and devonian bituminous shales and limestones have been metamorphosed and converted into graphitic rocks not very dissimilar to those in the less altered portions of the laurentian.[e] in like manner it seems probable that the numerous reticulating veins of graphite may have been formed by the segregation of bituminous matter into fissures and planes of least resistance, in the manner in which such veins occur in modern bituminous limestones and shales. such bituminous veins occur in the lower carboniferous limestone and shale of dorchester and hillsborough, new brunswick, with an arrangement very similar to that of the veins of graphite; and in the quebec rocks of point levi, veins attaining to a thickness of more than a foot, are filled with a coaly matter having a transverse columnar structure, and regarded by logan and hunt as an altered bitumen. these palæozoic analogies would lead us to infer that the larger part of the laurentian graphite falls under the second class of deposits above mentioned, and that, if of vegetable origin, the organic matter must have been thoroughly disintegrated and bituminised before it was changed into graphite. this would also give a probability that the vegetation implied was aquatic, or at least that it was accumulated under water. [e] granby, melbourne, owl's head, &c., "geology of canada," , p. . dr. hunt has, however, observed an indication of terrestrial vegetation, or at least of subaërial decay, in the great beds of laurentian iron-ore. these, if formed in the same manner as more modern deposits of this kind, would imply the reducing and solvent action of substances produced in the decay of plants. in this case such great ore-beds as that of hull, on the ottawa, seventy feet thick, or that near newborough, two hundred feet thick,[f] must represent a corresponding quantity of vegetable matter which has totally disappeared. it may be added that similar demands on vegetable matter as a deoxidising agent are made by the beds and veins of metallic sulphides of the laurentian, though some of the latter are no doubt of later date than the laurentian rocks themselves. [f] "geology of canada," . it would be very desirable to confirm such conclusions as those above deduced by the evidence of actual microscopic structure. it is to be observed, however, that when, in more modern sediments, algæ have been converted into bituminous matter, we cannot ordinarily obtain any structural evidence of the origin of such bitumen, and in the graphitic slates and limestones derived from the metamorphosis of such rocks no organic structure remains. it is true that, in certain bituminous shales and limestones of the silurian system, shreds of organic tissue can sometimes be detected, and in some cases, as in the lower silurian limestone of the la cloche mountains in canada, the pores of brachiopodous shells and the cells of corals have been penetrated by black bituminous matter, forming what may be regarded as natural injections, sometimes of much beauty. in correspondence with this, while in some laurentian graphitic rocks, as, for instance, in the compact graphite of clarendon, the carbon presents a curdled appearance due to segregation, and precisely similar to that of the bitumen in more modern bituminous rocks, i can detect in the graphitic limestones occasional fibrous structures which may be remains of plants, and in some specimens vermicular lines, which i believe to be tubes of eozoon penetrated by matter once bituminous, but now in the state of graphite. when palæozoic land-plants have been converted into graphite, they sometimes perfectly retain their structure. mineral charcoal, with structure, exists in the graphitic coal of rhode island. the fronds of ferns, with their minutest veins perfect, are preserved in the devonian shales of st. john, in the state of graphite; and in the same formation there are trunks of conifers (_dadoxylon ouangondianum_) in which the material of the cell-walls has been converted into graphite, while their cavities have been filled with calcareous spar and quartz, the finest structures being preserved quite as well as in comparatively unaltered specimens from the coal-formation.[g] no structures so perfect have as yet been detected in the laurentian, though in the largest of the three graphitic beds at st. john there appear to be fibrous structures, which i believe may indicate the existence of land-plants. this graphite is composed of contorted and slickensided laminæ, much like those of some bituminous shales and coarse coals; and in these are occasional small pyritous masses which show hollow carbonaceous fibres, in some cases presenting obscure indications of lateral pores. i regard these indications, however, as uncertain; and it is not as yet fully ascertained that these beds at st. john are on the same geological horizon with the lower laurentian of canada, though they certainly underlie the primordial series of the acadian group, and are separated from it by beds having the character of the huronian. [g] "acadian geology," p. . in calcined specimens the structures remain in the graphite after decalcification by an acid. there is thus no absolute impossibility that distinct organic tissues may be found in the laurentian graphite, if formed from land-plants, more especially if any plants existed at that time having true woody or vascular tissues; but it cannot with certainty be affirmed that such tissues have been found. it is possible, however, that in the laurentian period the vegetation of the land may have consisted wholly of cellular plants, as, for example, mosses and lichens; and if so, there would be comparatively little hope of the distinct preservation of their forms or tissues, or of our being able to distinguish the remains of land-plants from those of algæ. we may sum up these facts and considerations in the following statements: first, that somewhat obscure traces of organic structure can be detected in the laurentian graphite; secondly, that the general arrangement and microscopic structure of the substance corresponds with that of the carbonaceous and bituminous matters in marine formations of more modern date; thirdly, that if the laurentian graphite has been derived from vegetable matter, it has only undergone a metamorphosis similar in kind to that which organic matter in metamorphosed sediments of later age has experienced; fourthly, that the association of the graphitic matter with organic limestone, beds of iron-ore, and metallic sulphides greatly strengthens the probability of its vegetable origin; fifthly, that when we consider the immense thickness and extent of the eozoonal and graphitic limestones and iron-ore deposits of the laurentian, if we admit the organic origin of the limestone and graphite, we must be prepared to believe that the life of that early period, though it may have existed under low forms, was most copiously developed, and that it equalled, perhaps surpassed, in its results, in the way of geological accumulation, that of any subsequent period. many years ago, at the meeting of the american association in albany, the writer was carrying into the room of the geological section a mass of fossil wood from the devonian of gaspé, when he met the late professor agassiz, and remarked that the specimen was the remains of a devonian tree contemporaneous with his fishes of that age. "how i wish i could sit under its shade!" was the smiling reply of the great zoölogist; and when we think of the great accumulations of laurentian carbon, and that we are entirely ignorant of the forms and structures of the vegetation which produced it, we can scarcely suppress a feeling of disappointment. some things, however, we can safely infer from the facts that are known, and these it may be well to mention. the climate and atmosphere of the laurentian may have been well adapted for the sustenance of vegetable life. we can scarcely doubt that the internal heat of the earth still warmed the waters of the sea, and these warm waters must have diffused great quantities of mists and vapours over the land, giving a moist and equable if not a very clear atmosphere. the vast quantities of carbon dioxide afterwards sealed up in limestones and carbonaceous beds must also have still floated in the atmosphere and must have supplied abundance of the carbon, which constitutes the largest ingredient in vegetable tissues. under these circumstances the whole world must have resembled a damp, warm greenhouse, and plants loving such an atmosphere could have grown luxuriantly. in these circumstances the lower forms of aquatic vegetation and those that love damp, warm air and wet soil would have been at home. if we ask more particularly what kinds of plants might be expected to be introduced in such circumstances, we may obtain some information from the vegetation of the succeeding palæozoic age, when such conditions still continued to a modified extent. in this period the club-mosses, ferns, and mare's-tails engrossed the world and grew to sizes and attained degrees of complexity of structure not known in modern times. in the previous laurentian age something similar may have happened to algæ, to fungi, to lichens, to liverworts, and mosses. the algæ may have attained to gigantic dimensions, and may have even ascended out of the water in some of their forms. these comparatively simple cellular and tubular structures, now degraded to the humble position of flat lichens or soft or corky fungi, or slender cellular mosses, may have been so strengthened and modified as to constitute forest-trees. this would be quite in harmony with what is observed in the development of other plants in primitive geological times; and a little later in this history we shall see that there is evidence in the flora of the silurian of a survival of such forms. it may be that no geologist or botanist will ever be able to realise these dreams of the past. but, on the other hand, it is quite possible that some fortunate chance may have somewhere preserved specimens of laurentian plants showing their structure. in any case we have here presented to us the strange and startling fact that the remarkable arrangement of protoplasmic matter and chlorophyll, which enables the vegetable cell to perform, with the aid of solar light, the miracle of decomposing carbon dioxide and water, and forming with them woody and corky tissues, had already been introduced upon the earth. it has been well said that no amount of study of inorganic nature would ever have enabled any one to anticipate the possibility of the construction of an apparatus having the chemical powers of the living vegetable cell. yet this most marvellous structure seems to have been introduced in the full plenitude of its powers in the laurentian age. whether this early laurentian vegetation was the means of sustaining any animal life other than marine protozoa, we do not know. it may have existed for its own sake alone, or merely as a purifier of the atmosphere, in preparation for the future introduction of land-animals. the fact that there have existed, even in modern times, oceanic islands rich in vegetation, yet untenanted by the higher forms of animal life, prepares us to believe that such conditions may have been general or universal in the primeval times we are here considering. if we ask to what extent the carbon extracted from the atmosphere and stored up in the earth has been, or is likely to be, useful to man, the answer must be that it is not in a state to enable it to be used as mineral fuel. it has, however, important uses in the arts, though at present the supply seems rather in excess of the demand, and it may well be that there are uses of graphite still undiscovered, and to which it will yet be applied. finally, it is deserving of notice that, if laurentian graphite indicates vegetable life, it indicates this in vast profusion. that incalculable quantities of vegetable matter have been oxidised and have disappeared we may believe on the evidence of the vast beds of iron-ore; and, in regard to that preserved as graphite, it is certain that every inch of that mineral must indicate many feet of crude vegetable matter. it is remarkable that, in ascending from the laurentian, we do not at first appear to advance in evidences of plant-life. the huronian age, which succeeded the laurentian, seems to have been a disturbed and unquiet time, and, except in certain bands of iron-ore and some dark slates coloured with carbonaceous matter, we find in it no evidence of vegetation. in the cambrian a great subsidence of our continents began, which went on, though with local intermissions and reversals, all through the siluro-cambrian or ordovician time. these times were, for this reason, remarkable for the great abundance and increase of marine animals rather than of land-plants. still, there are some traces of land vegetation, and we may sketch first the facts of this kind which are known, and then advert to some points relating to the earlier algæ, or sea-weeds. an eminent swedish geologist, linnarsson, has described, under the name of _eophyton_, certain impressions on old cambrian rocks in sweden, and which certainly present very plant-like forms. they want, however, any trace of carbonaceous matter, and seem rather to be grooves or marks cut in clay by the limbs or tails of some aquatic animal, and afterwards filled up and preserved by succeeding deposits. after examining large series of these specimens from sweden, and from rocks of similar age in canada, i confess that i have no faith in their vegetable nature. the oldest plants known to me, and likely to have been of higher grade than algæ, are specimens kindly presented to me by dr. alleyne nicholson, of aberdeen, and which he had named _buthotrephis harknessii_[h] and _b. radiata_. they are from the skiddaw rocks of cumberland. on examining these specimens, and others subsequently collected in the same locality by dr. gr. m. dawson, while convinced by their form and carbonaceous character that they are really plants, i am inclined to refer them not to algæ, but probably to rhizocarps. they consist of slender branching stems, with whorls of elongate and pointed leaves, resembling the genus _annularia_ of the coal formation. i am inclined to believe that both of nicholson's species are parts of one plant, and for this i have proposed the generic name _protannularia_ (fig. ). somewhat higher in the siluro-cambrian, in the cincinnati group of america, lesquereux has found some minute radiated leaves, referred by him to the genus _sphenophyllum_,[i] which is also allied to rhizocarps. still more remarkable is the discovery in the same beds of a stem with rhombic areoles or leaf-bases, to which the name _protostigma_ has been given.[j] if a plant, this may have been allied to the club-mosses. this seems to be all that we at present know of land-vegetation in the siluro-cambrian. so far as the remains go, they indicate the presence of the families of rhizocarps and of lycopods. [h] "geological magazine," . [i] see figure in next chapter. [j] _protostigma sigillarioides_, lesquereux. [illustration: fig. .--_protannularia harknessii_ (nicholson), a probable rhizocarp of the ordovician period.] if we ascend into the upper silurian, or silurian proper, the evidences of land vegetation somewhat increase. in i described, in "the journal of the geological society" of london, a remarkable tree from the lower erian of gaspé, under the name _prototaxites_, but for which i now prefer the name _nematophyton_. when in london, in , i obtained permission to examine certain specimens of spore-cases or seeds from the upper ludlow (silurian) formation of england, and which had been described by sir joseph hooker under the name _pachytheca_. in the same slabs with these i found fragments of fossil wood identical with those of the gaspé plant. still later i recognised similar fragments associated also with _pachytheca_ in the silurian of cape bon ami, new brunswick. lastly, dr. hicks has discovered similar wood, and also similar fruits, in the denbighshire grits, at the base of the silurian.[k] [k] "journal of the geological society," august, . [illustration: fig. .--_nematophyton logani_ (magnified). vertical section.] [illustration: fig. .--_nematophyton logani_ (magnified). horizontal section, showing part of one of the radial spaces, with tubes passing into it.] [illustration: fig. .--_nematophyton logani_ (magnified). restoration.[l]] [l] figs. , , and are drawn from nature by prof. penhallow, of mcgill college. from comparison of this singular wood, the structure of which is represented in figs. , , , with the _débris_ of fossil taxine woods, mineralised after long maceration in water, i was inclined to regard _prototaxites_, or, as i have more recently named it, _nematophyton_, as a primeval gymnosperm allied to those trees which unger had described from the erian of thuringia, under the name _aporoxylon_.[m] later examples of more lax tissues from branches or young stems, and the elaborate examinations kindly undertaken for me by professor penhallow and referred to in a note to this chapter, have induced me to modify this view, and to hold that the tissues of these singular trees, which seem to have existed from the beginning of the silurian age and to have finally disappeared in the early erian, are altogether distinct from any form of vegetation hitherto known, and are possibly survivors of that prototypal flora to which i have already referred. they are trees of large size, with a coaly bark and large spreading roots, having the surface of the stem smooth or irregularly ribbed, but with a nodose or jointed appearance. internally, they show a tissue of long, cylindrical tubes, traversed by a complex network of horizontal tubes thinner walled and of smaller size. the tubes are arranged in concentric zones, which, if annual rings, would in some specimens indicate an age of one hundred and fifty years. there are also radiating spaces, which i was at first disposed to regard as true medullary rays, or which at least indicate a radiating arrangement of the tissue. they now seem to be spaces extending from the centre towards the circumference of the stem, and to have contained bundles of tubes gathered from the general tissue and extending outward perhaps to organs or appendages on the surface. carruthers has suggested a resemblance to algæ, and has even proposed to change the name to _nematophycus_, or "thread-sea-weed"; but the resemblance is by no means clear, and it would be quite as reasonable to compare the tissue to that of some fungi or lichens, or even to suppose that a plant composed of cylindrical tubes has been penetrated by the mycelium or spawn of a dry-rot fungus. but the tissues are too constant and too manifestly connected with each other to justify this last supposition. that the plant grew on land i cannot doubt, from its mode of occurrence; that it was of durable and resisting character is shown by its state of preservation; and the structure of the seeds called _pachytheca_, with their constant association with these trees, give countenance to the belief that they are the fruit of nematophyton. of the foliage or fronds of these strange plants we unfortunately know nothing. they seem, however, to realise the idea of arboreal plants having structures akin to those of thallophytes, but with seeds so large and complex that they can scarcely be regarded as mere spores. they should perhaps constitute a separate class or order to which the name _nematodendreæ_ may be given, and of which _nematophyton_ will constitute one genus and _aporoxylon_ of unger another.[n] [m] "palæontologie des thuringer waldes," . [n] see report by the author on "erian flora of canada," and , for full description of these fossils. another question arises as to the possible relation of these plants to other trees known by their external forms. the _protostigma_ of lesquereux has already been referred to, and claypole has described a tree from the clinton group of the united states, with large ovate leaf-bases, to which he has given the name _glyptodendron_.[o] if the markings on these plants are really leaf-bases, they can scarcely have been connected with _nematophyton_, because that tree shows no such surface-markings, though, as we have seen, it had bundles of tubes passing diagonally to the surface. these plants were more probably trees with an axis of barred vessels and thick, cellular bark, like the _lepidodendron_ of later periods, to be noticed in the sequel. dr. hicks has also described from the same series of beds which afforded the fragments of nematophyton certain carbonised dichotomous stems, which he has named _berwynia_. it is just possible that these plants may have belonged to the nematodendreæ. the thick and dense coaly matter which they show resembles the bark of these trees, the longitudinal striation in some of them may represent the fibrous structure, and the lateral projections which have been compared to leaves or leaf-bases may correspond with the superficial eminences of _nematophyton_, and the spirally arranged punctures which it shows on its surface. in this case i should be disposed to regard the supposed stigmaria-like roots as really stems, and the supposed rootlets as short, spine-like rudimentary leaves. all such comparisons must, however, in the mean time be regarded as conjectural. we seem, however, to have here a type of tree very dissimilar to any even of the later palæozoic age, which existed throughout the silurian, and probably further back, which ceased to exist early in the erian age, and before the appearance of the ordinary coniferous and lepidodendroid trees. may it not have been a survivor of an old arboreal flora extending back even to the laurentian itself? [o] "american journal of science," . multitudes of markings occurring on the surfaces of the older rocks have been referred to the algæ or sea-weeds, and indeed this group has been a sort of refuge for the destitute to which palæontologists have been accustomed to refer any anomalous or inexplicable form which, while probably organic, could not be definitely referred to the animal kingdom. there can be no question that some of these are truly marine plants; and that plants of this kind occur in formations older than those in which we first find land-plants, and that they have continued to inhabit the sea down to the present time. it is also true that the oldest of these algæ closely resemble in form plants of this kind still existing; and, since their simple cellular structures and soft tissues are scarcely ever preserved, their general forms are all that we can know, so that their exact resemblance to or difference from modern types can rarely be determined. for the same reasons it has proved difficult clearly to distinguish them from mere inorganic markings or the traces of animals, and the greatest divergence of opinion has occurred in recent times on these subjects, as any one can readily understand who consults the voluminous and well-illustrated memoirs of nathorst, williamson, saporta, and delgado. the author of this work has given much attention to these remains, and has not been disposed to claim for the vegetable kingdom so many of them as some of his contemporaries.[p] the considerations which seem most important in making such distinctions are the following: . the presence or absence of carbonaceous matter. true algæ not infrequently present at least a thin film of carbon representing their organic matter, and this is the more likely to occur in their case, as organic matters buried in marine deposits and not exposed to atmospheric oxidation are very likely to be preserved. . in the absence of organic matter, the staining of the containing rock, the disappearance or deoxidation of its ferruginous colouring matter, or the presence of iron pyrite may indicate the removal of organic matter by decay. . when organic matter and indications of it are altogether absent, and form alone remains, we have to distinguish from algæ, trails and burrows similar to those of aquatic animals, casts of shrinkage-cracks, water-marks, and rill-marks widely diffused over the surfaces of beds. . markings depressed on the upper surfaces of beds, and filled with the material of the succeeding layer, are usually mere impressions. the cases of possible exceptions to this are very rare. on the contrary, there are not infrequently forms in relief on the surfaces of rocks which are not algæ, but may be shallow burrows arched upward on top, or castings of worms thrown up upon the surface. sometimes, however, they may have been left by denudation of the surrounding material, just as footprints on dry snow remain in relief after the surrounding loose material has been drifted away by the wind; the portion consolidated by pressure being better able to resist the denuding agency. [p] "impressions and footprints of aquatic animals," "american journal of science," . [illustration: fig. .--trail of a modern king-crab, to illustrate imitations of plants sometimes named _bilobites_.] [illustration: fig. .--trail of carboniferous crustacean (_rusichnites acadicus_), nova scotia, to illustrate supposed algæ.] the footprints from the potsdam sandstone in canada, for which the name _protichnites_ was proposed by owen, and which were by him referred to crustaceans probably resembling _limulus_, were shown by the writer, in ,[q] to correspond precisely with those of the american limulus (_polyphemus occidentalis_) (fig. ). i proved by experiment with the modern animal that the recurring series of groups of markings were produced by the toes of the large posterior thoracic feet, the irregular scratches seen in _protichnites lineatus_ by the ordinary feet, and the central furrow by the tail. it was also shown that when the limulus uses its swimming-feet it produces impressions of the character of those named _climactichnites_, from the same beds which afford _protichnites_. the principal difference between _protichnites_ and their modern representatives is that the latter have two lateral furrows produced by the sides of the carapace, which are wanting in the former. [q] "canadian naturalist," vol. vii. i subsequently applied the same explanation to several other ancient forms now known under the general name _bilobites_ (figs. and ).[r] [r] the name bilobites was originally proposed by de kay for a bivalve shell (conocardium). its application to supposed algæ was an error, but this is of the less consequence, as these are not true plants but only animal trails. [illustration: fig. .--_rusophycus_ (_rusichnites_) _grenvillensis_, an animal burrow of the siluro-cambrian, probably of a crustacean, _a_, track connected with it.] the tuberculated impressions known as _phymatoderma_ and _caulerpites_ may, as zeiller has shown, be made by the burrowing of the mole-cricket, and fine examples occurring in the clinton formation of canada are probably the work of crustacea. it is probable, however, that some of the later forms referred to these genera are really algæ related to _caulerpa_, or even branches of conifers of the genus _brachyphyllum_. _nereites_ and _planulites_ are tracks and burrows of worms, with or without marks of setæ, and some of the markings referred to _palæochorda_, _palæophycus_, and _scolithus_ have their places here. many examples highly illustrative of the manner of formation of the impressions are afforded by canadian rocks (fig. ). branching forms referred to _licrophycus_ of billings, and some of those referred to _buthotrephis_, hall, as well as radiating markings referable to _scotolithus_, _gyrophyllites_, and _asterophycus_, are explained by the branching burrows of worms illustrated by nathorst and the author. _astropolithon_, a singular radiating marking of the canadian cambrian,[s] seems to be something organic, but of what nature is uncertain (fig. ). [s] supplement to "acadian geology." [illustration: fig. .--_palæophycus beverlyensis_ (billings), a supposed cambrian fucoid, but probably an animal trail.] _rhabdichnites_ and _eophyton_ belong to impressions explicable by the trails of drifting sea-weeds, the tail-markings of crustacea, and the ruts ploughed by bivalve mollusks, and occurring in the silurian, erian, and carboniferous rocks.[t] among these are the singular bilobate forms described as _rusophycus_ by hall, and which are probably burrows or resting-places of crustaceans. the tracks of such animals, when walking, are the jointed impressions known as _arthrophycus_ and _crusiana_. i have shown by the mode of occurrence of these, and nathorst has confirmed this conclusion by elaborate experiments on living animals, that these forms are really trails impressed on soft sediments by animals and mostly by crustaceans. [t] "canadian naturalist," . i agree with dr. williamson[u] in believing that all or nearly all the forms referred to crossochorda of schimper are really animal impressions allied to nereites, and due either to worms or, as nathorst has shown to be possible, to small crustaceans. many impressions of this kind occur in the silurian beds of the clinton series in canada and new york, and are undoubtedly mere markings. [u] "tracks from yoredale rocks," "manchester literary and philosophical society," . [illustration: fig. .--_astropolithon hindii_, an organism of the lower cambrian of nova scotia, possibly vegetable.] it is worthy of note that these markings strikingly resemble the so-called _eophyton_, described by torell from the primordial of sweden, and by billings from that of newfoundland; and which also occur abundantly in the primordial of new brunswick. after examining a series of these markings from sweden shown to me by mr. carruthers in london, and also specimens from newfoundland and a large number _in situ_ at st. john, i am convinced that they cannot be plants, but must be markings of the nature of _rhabdichnites_. this conclusion is based on the absence of carbonaceous matter, the intimate union of the markings with the surface of the stone, their indefinite forms, their want of nodes or appendages, and their markings being always of such a nature as could be produced by scratches of a sharp instrument. since, however, fishes are yet unknown in beds of this age, they may possibly be referred to the feet or spinous tails of swimming crustaceans. salter has already suggested this origin for some scratches of somewhat different form found in the primordial of great britain. he supposed them to have been the work of species of _hymenocaris_. these marks may, however, indicate the existence of some free-swimming animals of the primordial seas as yet unknown to us. three other suggestions merit consideration in this connection. one is that algæ and also land-plants, drifting with tides or currents, often make the most remarkable and fantastic trails. a marking of this kind has been observed by dr. g. m. dawson to be produced by a drifted laminaria, and in complexity it resembled the extraordinary _Ænigmichnus multiformis_ of hitchcock from the connecticut sandstones. much more simple markings of this kind would suffice to give species of _eophyton_. another is furnished by a fact stated to the author by prof. morse, namely, that lingulæ, when dislodged from their burrows, trail themselves over the bottom like worms, by means of their cirri. colonies of these creatures, so abundant in the primordial, may, when obliged to remove, have covered the surfaces of beds of mud with vermicular markings. the third is that the rhabdichnite-markings resemble some of the grooves in silurian rocks which have been referred to trails of gasteropods, as, for instance, those from the clinton group, described by hall. another kind of markings not even organic, but altogether depending on physical causes, are the beautiful branching rill-marks produced by the oozing of water out of mud and sand-banks left by the tide, and which sometimes cover great surfaces with the most elaborate tracery, on the modern tidal shores as well as in some of the most ancient rocks. _dendrophycus_[v] of lesquereux seems to be an example of rill-mark, as well as _aristophycus_, _cloephycus_, and _zygopliycus_, of miller and dyer, from the lower silurian. [v] "coal flora of pennsylvania," vol. iii., plate . rill-marks occur in very old rocks,[w] but are perhaps most beautifully preserved in the carboniferous shales and argillaceous sandstones, and even more elaborately on the modern mud-banks of the bay of fundy.[x] some of these simulate ferns and fronds of laminariæ, and others resemble roots, fucoids allied to _buthotrephis_, or the radiating worm-burrows already referred to (fig. ). [w] "journal of the geological society," vol. xii., p. . [x] "acadian geology," d ed., p. . [illustration: fig. .--carboniferous rill-mark (nova scotia), reduced, to illustrate pretended algæ.] _shrinkage-cracks_ are also abundant in some of the carboniferous beds, and are sometimes accompanied with impressions of rain-drops. when finely reticulated they might be mistaken for the venation of leaves, and, when complicated with little rill-marks tributary to their sides, they precisely resemble the _dictyolites_ of hall from the medina sandstone (fig. ). [illustration: fig. .--cast of shrinkage cracks (carboniferous, nova scotia), illustrating pretended algæ.] an entirely different kind of shrinkage-crack is that which occurs in certain carbonised and flattened plants, and which sometimes communicates to them a marvellous resemblance to the netted under surface of an exogenous leaf. flattened stems of plants and layers of cortical matter, when carbonised, shrink in such a manner as to produce minute reticulated cracks. these become filled with mineral matter before the coaly substance has been completely consolidated. a further compression occurs, causing the coaly substance to collapse, leaving the little veins of harder mineral matter projecting. these impress their form upon the clay or shale above and below, and thus when the mass is broken open we have a carbonaceous film or thin layer covered with a network of raised lines, and corresponding minute depressed lines on the shale in contact with it. the reticulations are generally irregular, but sometimes they very closely resemble the veins of a reticulately veined leaf. one of the most curious specimens in my possession was collected by mr. elder in the lower carboniferous of horton bluff. the little veins which form the projecting network are in this case white calcite; but at the surface their projecting edges are blackened with a carbonaceous film. _slickensided bodies_, resembling the fossil fruits described by geinitz as _gulielmites_, and the objects believed by fleming and carruthers[y] to be casts of cavities filled with fluid, abound in the shales of the carboniferous and devonian. they are, no doubt, in most cases the results of the pressure and consolidation of the clay around small solid bodies, whether organic, fragmentary, or concretionary. they are, in short, local slickensides precisely similar to those found so plentifully in the coal under-clays, and which, as i have elsewhere[z] shown, resulted from the internal giving way and slipping of the mass as the roots of stigmaria decayed within it. most collectors of fossil plants in the older formations must, i presume, be familiar with appearances of this kind in connection with small stems, petioles, fragments of wood, and carpolites. i have in my collection petioles of ferns and fruits of the genus trigonocarpum partially slickensided in this way, and which if wholly covered by this kind of marking could scarcely have been recognised. i have figured bodies of this kind in my report on the devonian and upper silurian plants of canada, believing them, owing to their carbonaceous covering, to be probably slickensided fruits, though of uncertain nature. in every case i think these bodies must have had a solid nucleus of some sort, as the severe pressure implied in slickensiding is quite incompatible with a mere "fluid-cavity," even supposing this to have existed. [y] "journal of the geological society," june, . [z] _ibid._, vol. x., p. . prof. marsh has well explained another phase of the influence of hard bodies in producing partial slickensides, in his paper on _stylolites_, read before the american association in , and the application of the combined forces of concretionary action and slickensiding to the production of the cone-in-cone concretions, which occur in the coal-formation and as low as the primordial. i have figured a very perfect and beautiful form of this kind from the coal-formation of nova scotia, which is described in "acadian geology"[aa] (fig. ). i have referred to these facts here because they are relatively more important in that older period, which may be named the age of algæ, and because their settlement now will enable us to dispense with discussions of this kind further on. the able memoirs of nathorst and williamson should be studied by those who desire further information. [aa] appendix, p. , edition of . [illustration: fig. .--cone-in-cone concretion (carboniferous, nova scotia), illustrating pretended algæ.] but it may be asked, "are there no real examples of fossil algæ?" i believe there are many such, but the difficulty is to distinguish them. confining ourselves to the older rocks, the following may be noted: the genus _buthotrephis_ of hall, which is characterised as having stems, sub-cylindric or compressed, with numerous branches, which are divaricating and sometimes leaf-like, contains some true algæ. hall's _b. gracilis_, from the siluro-cambrian, is one of these. similar plants, referred to the same species, occur in the clinton and niagara formations, and a beautiful species, collected by col. grant, of hamilton, and now in the mcgill college collection, represents a broader and more frondose type of distinctly carbonaceous character. it may be described as follows: _buthotrephis grantii_, s. n. (fig. ).--stems and fronds smooth and slightly striate longitudinally, with curved and interrupted striæ. stem thick, bifurcating, the divisions terminating in irregularly pinnate fronds, apparently truncate at the extremities. the quantity of carbonaceous matter present would indicate thick, though perhaps flattened, stems and dense fleshy fronds. [illustration: fig. .--_buthotrephis grantii_, a genuine alga from the silurian, canada.] the species _buthotrephis subnodosa_ and _b. flexuosa_, from the utica shale, are also certainly plants, though it is possible, if their structures and fruit were known, some of these might be referred to different genera. all of these plants have either carbonaceous matter or produce organic stains on the matrix. the organism with diverging wedge-shaped fronds, described by hall as _sphenothallus angustifolius_, is also a plant. fine specimens, in the collection of the geological survey of canada, show distinct evidence of the organic character of the wedge-shaped fronds. it is from the utica shale, and elsewhere in the siluro-cambrian. it is just possible, as suggested by hall, that this plant may be of higher rank than the algæ. the genus _palæophycus_ of hall includes a great variety of uncertain objects, of which only a few are probably true algæ. i have specimens of fragments similar to his _p. virgatus_, which show distinct carbonaceous films, and others from the quebec group, which seem to be cylindrical tubes now flattened, and which have contained spindle-shaped sporangia of large size. tortuous and curved flattened stems, or fronds, from the upper silurian limestone of gaspé, also show organic matter. respecting the forms referred to _licrophycus_ by billings, containing stems or semi-cylindrical markings springing from a common base, i have been in great doubt. i have not seen any specimens containing unequivocal organic matter, and am inclined to think that most of them, if not the whole, are casts of worm-burrows, with trails radiating from them. though i have confined myself in this notice to plants, or supposed plants, of the lower palæozoic, it may be well to mention the remarkable cauda-galli fucoids, referred by hall to the genus _spirophyton_, and which are characteristic of the oldest erian beds. the specimens which i have seen from new york, from gaspé, and from brazil, leave no doubt in my mind that these were really marine plants, and that the form of a spiral frond, assigned to them by hall, is perfectly correct. they must have been very abundant and very graceful plants of the early erian, immediately after the close of the silurian period. we come now to notice certain organisms referred to algæ, and which are either of animal origin, or are of higher grade than the sea-weeds. we have already discussed the questions relating to _prototaxites_. _drepanophycus_, of goeppert,[ab] i suspect, is only a badly preserved branch or stem of the erian land-plant known as arthrostigma. in like manner, _haliserites dechenianus_,[ac] of goeppert, is evidently the land-plant known as _psilophyton_. _sphærococcites dentatus_ and _s. serra_--the _fucoides dentatus_ and _serra_ of brongniart, from quebec--are graptolites of two species quite common there.[ad] _dictyophyton_ and _uphantenia_, as described by hall and the author, are now known to be sponges. they have become _dictyospongiæ_. the curious and very ancient; fossils referred by forbes to the genus _oldhamia_ are perhaps still subject to doubt, but are usually regarded as zoöphytes, though it is quite possible they may be plants. though i have not seen the specimens, i have no doubt whatever that the plants, or the greater part of them, from the silurian of bohemia, described by stur as algæ and characeæ,[ae] are really land-plants, some of them of the genus _psilophyton_. i may say in this connection that specimens of flattened _psilophyton_ and _arthrostigma_, in the upper silurian and erian of gaspé, would probably have been referred to algæ, but for the fact that in some of them the axis of barred vessels is preserved. [ab] "fossile flora," , p. , table xli. [ac] _ibid._, p. , table ii. [ad] brongniart, "vegeteaux fossiles," plate vi., figs. to . [ae] "proceedings of the vienna academy," . _hostinella_, of this author, is almost certainly _psilophyton_, and his _barrandiana_ seems to include _arthrostigma_, and perhaps leafy branches of _berwynia_. these curious plants should be re-examined. it is not surprising that great difficulties have occurred in the determination of fossil algæ. enough, however, remains certain to prove that the old cambrian and silurian seas were tenanted with sea-weeds not very dissimilar from those of the present time. it is further probable that some of the graphitic, carbonaceous, and bituminous shales and limestones of the silurian owe their carbonaceous matters to the decomposition of algæ, though possibly some of it may have been derived from graptolites and other corneous zoöphytes. in any case, such microscopic examinations of these shales as i have made, have not produced any evidence of the existence of plants of higher grade, while those of the erian and carboniferous periods, similar to the naked eye, abound in such evidence. it is also to be observed that, on the surfaces of beds of sandstone in the upper cambrian, carbonaceous _débris_, which seems to be the remains of either aquatic or land plants, is locally not infrequent. [illustration: fig. .--silurian vegetation restored. _protannularia_, _berwynia_, _nematophyton_, _sphenophyllum_, _arthrostigma_, _psilophyton_.] referring to the land vegetation of the older rocks, it is difficult to picture its nature and appearance. we may imagine the shallow waters filled with aquatic or amphibious rhizocarpean plants, vast meadows or brakes of the delicate _psilophyton_ and the starry _protannularia_ and some tall trees, perhaps looking like gigantic club-mosses, or possibly with broad, flabby leaves, mostly cellular in texture, and resembling algæ transferred to the air. imagination can, however, scarcely realise this strange and grotesque vegetation, which, though possibly copious and luxuriant, must have been simple and monotonous in aspect, and, though it must have produced spores and seeds and even fruits, these were probably all of the types seen in the modern acrogens and gymnosperms. "in garments green, indistinct in the twilight, they stand like druids of old, with voices sad and prophetic." prophetic they truly were, as we shall find, of the more varied forests of succeeding times, and they may also help us to realise the aspect of that still older vegetation, which is fossilised in the laurentian graphite; though it is not impossible that this last may have been of higher and more varied types, and that the cambrian and silurian may have been times of depression in the vegetable world, as they certainly were in the submergence of much of the land. these primeval woods served at least to clothe the nakedness of the new-born land, and they may have sheltered and nourished forms of land-life still unknown to us, as we find as yet only a few insects and scorpions in the silurian. they possibly also served to abstract from the atmosphere some portion of its superabundant carbonic acid harmful to animal life, and they stored up supplies of graphite, of petroleum, and of illuminating gas, useful to man at the present day. we may write of them and draw their forms with, the carbon which they themselves supplied. * * * * * note to chapter ii. examination of prototaxites (_nematophyton_), by prof. penhallow, of mcgill university. prof. penhallow, having kindly consented to re-examine my specimens, has furnished me with elaborate notes of his facts and conclusions, of which the following is a summary, but which it is hoped will be published in full: " . _concentric layers._--the inner face of each of these is composed of relatively large tubes, having diameters from · to · micro-millimetres. the outer face has tubes ranging from · to · mm. the average diameter in the lower surface approaches to , that in the outer to · . there is, however, no abrupt termination to the surface of the layers, though in some specimens they separate easily, with shining surfaces. " . _minute structure._--in longitudinal sections the principal part of the structure consists of longitudinal tubes of indeterminate length, and round in cross-section. they are approximately parallel, but in some cases may be seen to bend sinuously, and are not in direct contact. finer myceloid tubes, · mm. in diameter, traverse the structure in all directions, and are believed to branch off from the larger tubes. in a small specimen supposed to be a branch or small stem, and in which the vertical tubes are somewhat distant from one another, this horizontal system is very largely developed; but is less manifest in the older stems. the tubes themselves show no structure. the ray-like openings in the substance of the tissue are evidently original parts of the structure, but not of the nature of medullary rays. they are radiating spaces running outward in an interrupted manner or so tortuously that they appear to be interrupted in their course from the centre towards the surface. they show tubes turning into them, branching into them, and approximately horizontal, but tortuous. on the external surface of some specimens these radial spaces are represented by minute pits irregularly or spirally arranged. the transverse swellings of the stem show no difference of structure, except that the tubes or cells may be a little more tortuous, and a transverse film of coaly matter extends from the outer coaly envelope inwardly. this may perhaps be caused by some accident of preservation. the outer coaly layer shows tubes similar to those of the stem.[af] the horizontal or oblique flexures of the large tubes seem to be mainly in the vicinity of the radial openings, and it is in entering these that they have been seen to branch." [af] it is possible that these tubes may be merely part of the stem attached to the bark, which seems to me to indicate the same dense cellular structure seen in the bark of _lepidodendra_, etc. the conclusions arrived at by prof. penhallow are as follows: " . the plant was not truly exogenous, and the appearance of rings is independent of the causes which determine the layers of growth in exogenous plants. " . the plant was possessed of no true bark. whatever cortical layer was present was in all probability a modification of the general structure,[ag] [ag] on these points i would reserve the considerations: . that there must have been some relation between the mode of growth of these great stems and their concentric rings; and, . that the evidence of a bark is as strong as in the case of any palæozoic tree in which the bark is, as usual, carbonised. " . an intimate relation exists between the large tubular cells and the myceloid filaments, the latter being a system of small branches from the former; the branching being determined chiefly in certain special openings which simulate medullary rays. " . the specimens examined exhibit no evidence of special decay, and the structure throughout is of a normal character. " . the primary structure consists of large tubular cells without apparent terminations, and devoid of structural markings, with which is associated a secondary structure of myceloid filaments arising from the former. " . the structure of _nematophyton_ as a whole is unique; at least there is no plant of modern type with which it is comparable. nevertheless, the loose character of the entire structure; the interminable cells; their interlacing; and, finally, their branching into a secondary series of smaller filaments, point with considerable force to the true relationship of the stem as being with algæ or other thallophytes rather than with grymnosperms. a more recent examination of a laminated resinous substance found associated with the plant shows that it is wholly amorphous, and, as indicated by distinct lines of flow, that it must have been in a plastic state at a former period. the only evidence of structure was found in certain well-defined mycelia, which may have been derived from associated vegetable matter upon which they were growing, and over which the plastic matrix flowed." i have only to add to this description that when we consider that _nematophyton logani_ was a large tree, sometimes attaining a diameter of more than two feet, and a stature of at least twenty before branching; that it had great roots, and gave off large branches; that it was an aërial plant, probably flourishing in the same swampy flats with _psilophyton_, _arthrostigma_, and _leptophleum_; that the peculiar bodies known as pachytheca were not unlikely its fruit--we have evidence that there were, in the early palæozoic period, plants scarcely dreamt of by modern botany. only when the appendages of these plants are more fully known can we hope to understand them. in the mean time, i may state that there were probably different species of these trees, indicated more particularly by the stems i have described as _nematoxylon_ and _celluloxylon_[ah] there were, i think, some indications that the plants described by carruthers as _berwynia_, may also be found to have been generically the same. the resinous matter mentioned by prof. penhallow is found in great abundance in the beds containing _nematophyton_, and must, i think, have been an exudation from its bark. [ah] "journal geol. society of london," , . chapter iii. the erian of devonian forests--origin of petroleum--the age of acrogens and gymnosperms. in the last chapter we were occupied with the comparatively few and obscure remains of plants entombed in the oldest geological formations. we now ascend to a higher plane, that of the erian or devonian period, in which, for the first time, we find varied and widely distributed forests. the growth of knowledge with respect to this flora has been somewhat rapid, and it may be interesting to note its principal stages, as an encouragement to the hope that we may yet learn something more satisfactory respecting the older floras we have just discussed. in goeppert's memoir on the flora of the silurian, devonian, and lower carboniferous rocks, published in ,[ai] he enumerates twenty species as silurian, but these are all admitted to be algæ, and several of them are remains which may be fairly claimed by the zoologists as zoophytes, or trails of worms and mollusks. in the lower devonian he knows but six species, five of which are algæ, and the remaining one a _sigillaria_, but this is of very doubtful nature. in the middle devonian he gives but one species, a land-plant of the genus _lepidodendron_. in the upper devonian the number rises to fifty-seven, of which all but seven are terrestrial plants, representing a large number of the genera occurring in the succeeding carboniferous system. [ai] jena, . goeppert does not include in his enumeration the plants from the devonian of gaspé, described by the author in ,[aj] having seen only an abstract of the paper at the time of writing his memoir, nor does he appear to have any knowledge of the plants of this age described by lesquereux in roger's "pennsylvania." these might have added ten or twelve species to his list, some of them probably from the lower devonian. it is further to be observed that a few additional species had also been recognised by peach in the old red sandstone of scotland. [aj] "journal of the geological society of london," also "canadian naturalist." but from to the present time a rich harvest of specimens has been gathered from the gaspé sandstones, from the shales of southern new brunswick, from the sandstones of perry in maine, and from the wide-spread erian areas of new york, pennsylvania, and ohio. nearly all these specimens have passed through my hands, and i am now able to catalogue about a hundred species, representing more than thirty genera, and including all the great types of vascular cryptogams, the gymnosperms, and even one (still doubtful) angiosperm. many new forms have also been described from the devonian of scotland and of the continent of europe. before describing these plants in detail, we may refer to north america for illustration of the physical conditions of the time. in a physical point of view the northern hemisphere presented a great change in the erian period. there were vast foldings of the crust of the earth, and great emissions of volcanic rock on both sides of the atlantic. in north america, while at one time the whole interior area of the continent, as far north as the great lakes, was occupied by a vast inland sea, studded with coral islands, the long appalachian ridge had begun to assume, along with the old laurentian land, something of the form of our present continent, and on the margins of this appalachian belt there were wide, swampy flats and shallow-water areas, which, under the mild climate that seems to have characterised this period, were admirably suited to nourish a luxuriant vegetation. under this mild climate, also, it would seem that new forms of plants were first introduced in the far north, where the long continuance of summer sunlight, along with great warm th, seems to have aided in their introduction and early extension, and thence made their way to the southward, a process which, as gray and others have shown, has also occurred in later geological times. the america of this erian age consisted during the greater part of the period of a more or less extensive belt of land in the north with two long tongues descending from it, one along the appalachian line in the east, the other in the region west of the rocky mountains. on the seaward sides of these there were low lands covered with vegetation, while on the inland side the great interior sea, with its verdant and wooded islands, realised, though probably with shallower water, the conditions of the modern archipelagoes of the pacific. europe presented conditions somewhat similar, having in the earlier and middle portions of the period great sea areas with insular patches of land, and later wide tracts of shallow and in part enclosed water areas, swarming with fishes, and having an abundant vegetation on their shores. these were the conditions of the eifel and devonshire limestones, and of the old red sandstone of scotland, and the kiltorcan beds of ireland. in europe also, as in america, there were in the erian age great ejections of igneous rock. on both sides of the atlantic there were somewhat varied and changing conditions of land and water, and a mild and equable climate, permitting the existence of a rich vegetation in high northern latitudes. of this latter fact a remarkable example is afforded by the beds holding plants of this age in spitzbergen and bear island, in its vicinity. here there seem to be two series of plant-bearing strata, one with the vegetation of the upper erian, the other with that of the lower carboniferous, though both have been united by heer under his so-called "ursa stage" in which he has grouped the characteristic plants of two distinct periods. this has recently been fully established by the researches of nathorst, though the author had already suggested it as the probable explanation of the strange union of species in the ursa group of heer. in studying the vegetation of this remarkable period, we must take merely some of the more important forms as examples, since it would be impossible to notice all the species, and some of them may be better treated in the carboniferous, where they have their headquarters. (fig. .) i may first refer to a family which seems to have culminated in the erian age, and ever since to have occupied a less important place. it is that of the curious aquatic plants known as rhizocarps,[ak] and referred to in the last chapter. [ak] or, as they have recently been named by some botanists, "heterosporous filices," though they are certainly not ferns in any ordinary sense of that term. my attention was first directed to these organisms by the late sir w. e. logan in . he had obtained from the upper erian shale of kettle point, lake huron, specimens filled with minute circular discs, to which he referred, in his report of , as "microscopic orbicular bodies." recognising them to be macrospores, or spore-cases, i introduced them into the report on the erian flora, which i was then preparing, and which was published in , under the name _sporangites huronensis_. [illustration: fig. .--vegetation of the devonian period, restored. _calamites_, _psilophyton_, _leptophleum_, _lepidodendron_, _cordaites_, _sigillaria_, _dadoxylon_, _asterophyllites_, _platyphyllum_.] in , having occasion to write a communication to the "american journal of science" on the question then raised as to the share of spores and spore-cases in the accumulation of coal, a question to be discussed in a subsequent chapter, these curious little bodies were again reviewed, and were described in substance as follows: "the oldest bed of spore-cases known to me is that at kettle point, lake huron. it is a bed of brown bituminous shale, burning with much flame, and under a lens is seen to be studded with flattened disc-like bodies, scarcely more than a hundredth of an inch in diameter, which under the microscope are found to be spore-cases (or macrospores) slightly papillate externally (or more properly marked with dark pores), and sometimes showing a point of attachment on one side and a slit more or less elongated and gaping on the other. when slices of the rock are made, its substance is seen to be filled with these bodies, which, viewed as transparent objects, appear yellow like amber, and show little structure, except that the walls can be distinguished from the internal cavity, which may sometimes be seen to enclose patches of granular matter. in the shale containing them are also vast numbers of rounded, translucent granules, which may be escaped spores (microspores)." the bed containing these spores at kettle point was stated, in the reports of the "geological survey of canada," to be twelve or fourteen feet in thickness, and besides these specimens it contained fossil plants referable to the species _calamites inornatus_ and _lepidodendron primævum_, and i not unnaturally supposed that the sporangites might be the fruit of the latter plant. i also noticed their resemblance to the spore-cases of _l. corrugatum_ of the lower carboniferous (a lepidodendron allied to _l. primævum_), and to those from brazil described by carruthers under the name _flemingites_, as well as to those described by huxley from certain english coals, and to those of the tasmanite or white coal of australia. the bed at kettle point is shown to be marine by its holding the sea-weed known as _spirophyton_, and shells of _lingula_. the subject did not again come under my notice till , when prof. orton, of columbus, ohio, sent me some specimens from the erian shales of that state, which on comparison seemed undistinguishable from _sporangites huronensis_.[al] prof. orton read an interesting paper on these bodies, at the meeting of the american association in montreal, in which were some new and striking facts. one of these was the occurrence of such bodies throughout the black shales of ohio, extending "from the huron river, on the shore of lake brie, to the mouth of the scioto, in the ohio valley, with an extent varying from ten to twenty miles in breadth," and estimated to be three hundred and fifty feet in thickness. i have since been informed by my friend mr. thomas, of chicago, that its thickness, in some places at least, must be three times that amount. about the same time. prof. williams, of cornell, and prof. clarke, of northampton, announced similar discoveries in the state of new york, so that it would appear that beds of vast area and of great thickness are replete with these little vegetable discs, usually converted into a highly bituminous, amber-like substance, giving a more or less inflammable character to the containing rock. [al] these shales have been described, as to their chemical and geological relations, by dr. t. sterry hunt, "american journal of science," , and by dr. newberry, in the "reports of the geological survey of ohio," vol. i., , and vol. iii., . another fact insisted on by prof. orton was the absence of lepidodendroid cones, and the occurrence of filamentous vegetable matter, to which the sporangites seemed to be in some cases attached in groups. prof. orton also noticed the absence of the trigonal form, which belongs to the spores of many lepidodendra, though this is not a constant character. in the discussion on prof. orton's paper, i admitted that the facts detailed by him shook my previous belief of the lycopodiaceous character of these bodies, and induced me to suspect, with prof. orton, that they might have belonged to some group of aquatic plants lower than the lycopods. since the publication of my paper on rhizocarps in the palæozoic period above referred to, i have received two papers from mr. edward wethered, f. g. s., in one of which he describes spores of plants found in the lower limestone shales of the forest of dean, and in the other discusses more generally the structure and origin of carboniferous coal-beds.[am] in both papers he refers to the occurrence in these coals and shales of organisms essentially similar to the erian spores. [am] "cotteswold naturalists' field club," ; "journal of the royal microscopical society," . in the "bulletin of the chicago academy of science," january, , dr. johnson and mr. thomas, in their paper on the "microscopic organisms of the boulder clay of chicago and vicinity," notice _sporangites huronensis_ as among these organisms, and have discovered them also in large numbers in the precipitate from chicago city water-supply. they refer them to the decomposition of the erian shales, of which boulders filled with these organisms are of frequent occurrence in the chicago clays. the sporangites and their accompaniments in the boulder clay are noticed in a paper by dr. g. m. dawson, in the "bulletin of the chicago academy," june, . prof. clarke has also described, in the "american journal of science" for april, , the forms already alluded to, and which he finds to consist of macrospores enclosed in sporocarps. he compares these with my _sporangites huronensis_ and _protosalvinia bilobata_, but i think it is likely that one of them at least is a distinct species. i may add that in the "geological magazine" for , mr. newton, f. g. s., of the geological survey of england, published a description of the tasmanite and australian white coal, in which he shows that the organisms in these deposits are similar to my _sporangites huronensis_, and to the macrospores previously described by prof. huxley, from the better-bed coal. mr. newton does not seem to have been aware of my previous description of _sporangites_, and proposes the name _tasmanites punctatus_ for the australian form. here we have the remarkable fact that the waste macrospores, or larger spores of a species of cryptogamous plant, occur dispersed in countless millions of tons through the shales of the erian in canada and the united states. no certain clue seemed to be afforded by all these observations as to the precise affinities of these widely distributed bodies; but this was furnished shortly after from an unexpected quarter. in march, , mr. orville derby, of the geological survey of brazil, sent me specimens found in the erian of that country, which seemed to throw a new light on the whole subject. these i described and pointed out their connection with _sporangites_ at the meeting of the american association at minneapolis, in , and subsequently published my notes respecting them in its proceedings, and in the "canadian record of science." mr. derby's specimens contained the curious spiral sea-weed known as _spirophyton_, and also minute rounded sporangites like those obtained in the erian of ohio, and of which specimens had been sent to me some years before by the late prof. hartt. but they differed in showing the remarkable fact that these rounded bodies are enclosed in considerable numbers in spherical and oval sacs, the walls of which are composed of a tissue of hexagonal cells, and which resemble in every respect the involucres or spore-sacs of the little group of modern acrogens known as rhizocarps, and living in shallow water. more especially they resemble the sporocarps of the genus _salvinia_. this fact opened up an entirely new field of investigation, and i at once proceeded to compare the specimens with the fructification of modern rhizocarps, and found that substantially these multitudinous spores embedded in the erie shales may be regarded as perfectly analogous to the larger spores of the modern _salvinia natans_ of europe, as may be seen by the representation of them in fig. . [illustration: fig. .--_sporangites_ (_protosalvinia_). a, _sporangites braziliensis_, natural size, ax, same, magnified, b, _sp. biloba_, natural size, c, detached macrospores. d, spore-cases of salvinia natans. dx, same, magnified. e, shale with sporangites, vertical section, highly magnified.] the typical macrospores from the erian shales are perfectly circular in outline, and in the flattened state appear as discs with rounded edges, their ordinary diameter being from one seventy-fifth to one one-hundredth of an inch, though they vary considerably in size. this, however, i do not regard as an essential character. the edges, as seen in profile, are smooth, but the flat surface often presents minute dark spots, which at first i mistook for papillæ, but now agree with mr. thomas in recognising them as minute pores traversing the wall of the disc, and similar to those which mr. newton has described in tasmanite, and which mr. wethered has also recognised in the similar spores of the forest of dean shales. the walls also sometimes show faint indications of concentric lamination, as if they had been thickened by successive deposits. as seen by transmitted light, and either in front or in profile, the discs are of a rich amber colour, translucent and structureless, except the pores above referred to. the walls are somewhat thick, or from one-tenth to one-twentieth the diameter of the disc in thickness. they never exhibit the triradiate marking seen in spores of lycopods, nor any definite point of attachment, though they sometimes show a minute elongated spot which may be of this nature, and they are occasionally seen to have opened by slits on the edge or front, where there would seem to have been a natural line of dehiscence. the interior is usually quite vacant or structureless, but in some cases there are curved internal markings which may indicate a shrunken lining membrane, or the remains of a prothallus or embryo. occasionally a fine granular substance appears in the interior, possibly remains of microspores. the discs are usually detached and destitute of any envelope, but fragments of flocculent cellular matter are associated with them, and in one specimen from the corniferous limestone of ohio, in mr. thomas's collection, i have found a group of eight or more discs partly enclosed in a cellular sac-like membrane of similar character to that enclosing the brazilian specimens already referred to. the characters of all the specimens are essentially similar, and there is a remarkable absence of other organisms in the shale. in one instance only, i have observed a somewhat smaller round body with a dark centre or nucleus, and a wide translucent margin, marked by a slight granulation. even this, however, may indicate nothing more than a different state of preservation. it is proper to observe here that the wall or enclosing sac of these macrospores must have been of very dense consistency, and now appears as a highly bituminous substance, in this agreeing with that of the spores of lycopods, and, like them, having been when recent of a highly carbonaceous and hydrogenous quality, very combustible and readily admitting of change into bituminous matter. in the paper already referred to, on spore-cases in coals, i have noticed that the relative composition of lycopodium and cellulose is as follows: cellulose, c{ }h{ }o{ }. lycopodium, c{ }h{ - / }no{ - / }. thus, such spores are admirably suited for the production of highly carbonaceous or bituminous coals, etc. nothing is more remarkable in connection with these bodies than their uniformity of structure and form over so great areas and throughout so great thickness of rock, and the absence of any other kind of spore-case. this is more especially noteworthy in contrast with the coarse coals and bituminous shales of the carboniferous, which usually contain a great variety of spores and sporangia, indicating the presence of many species of acrogenous plants, while the erian shales, on the contrary, indicate the almost exclusive predominance of one form. this contrast is well seen in the bedford shales overlying these beds, and i believe lower carboniferous.[an] specimens of these have been kindly communicated to me by prof. orton, and have been prepared by mr. thomas. in these we see the familiar carboniferous spores with triradiate markings called _triletes_ by reinsch, and which are similar to those of lycopodiaceous plants. still more abundant are those spinous and hooked spores or sporangia, to which the names _sporocarpon_, _zygosporites_, and _traquaria_ have been given, and some of which williamson has shown to be spores of lycopodiaceous plants.[ao] [an] according to newberry, lower part of waverly group. [ao] _traquaria_ is to be distinguished from the calcareous bodies found in the corniferous limestone of kelly's island, which i have described in the "canadian naturalist" as _saccamina eriana_, and believe to be foraminiferal tests. they have since been described by ulrich under a different name (_moellerina_: contribution to "american palæontology," ). see dr. williamson's papers in "transactions of royal society of london." the true "sporangites," on the contrary, are round and smooth, with thick bituminous walls, which are punctured with minute transverse pores. in these respects, as already stated, they closely resemble the bodies found in the australian white coal and tasmanite. the precise geological age of this last material is not known with certainty, but it is believed to be palæozoic. with reference to the mode of occurrence of these bodies, we may note first their great abundance and wide distribution. the horizontal range of the bed at kettle point is not certainly known, but it is merely a northern outlier of the great belt of erian shales referred to by prof. orton, and which extends, with a breadth of ten to twenty miles, and of great thickness, across the state of ohio, for nearly two hundred miles. this ohio black shale, which lies at the top of the erian or the base of the carboniferous, though probably mainly of erian age, appears to abound throughout in these organisms, and in some beds to be replete with them. in like manner, in brazil, according to mr. derby, these organisms are distributed over a wide area and throughout a great thickness of shale holding _spirophyton_, and apparently belonging to the upper erian. the recurrence of similar forms in the tasmanite and white coal of tasmania and australia is another important fact of distribution. to this we may add the appearance of these macrospores in coals and shales of the carboniferous period, though there in association with other forms. it is also to be observed that the erian shales, and the forest of dean beds described by wethered, are marine, as shown by their contained fossils; and, though i have no certain information as to the tasmanite and australian white coal, they would seem, from the description of milligan, to occur in distinctly aqueous, possibly estuarine, deposits. wethered has shown that the discs described by huxley and newton in the better-bed coal occur in the earthy or fragmentary layers, as distinguished from the pure coal. those occurring in cannel coal are in the same case, so that the general mode of occurrence implies water-driftage, since, in the case of bodies so large and dense, wind-driftage to great distances would be impossible. these facts, taken in connection with the differences between these macrospores and those of any known land-plant of the palæozoic, would lead to the inference that they belonged to aquatic plants, and these vastly abundant in the waters of the erian and carboniferous periods. it is still further to be observed that they are not, in the erian beds, accompanied with any remains of woody or scalariform tissues, such as might be expected in connection with the _débris_ of terrestrial acrogens, and that, on the other hand, we find them enclosed in cellular sporocarps, though in the majority of cases these have been removed by dehiscence or decay. these considerations, i think, all point to the probability which i have suggested in my papers on this subject referred to above, that we have in these objects the organs of fructification of plants belonging to the order _rhizocarpeæ_, or akin to it. the comparisons which i have instituted with the sporocarps and macrospores of these plants confirm this suggestion. of the modern species which i have had an opportunity to examine, _salvinia natans_ of europe perhaps presents the closest resemblance. in this plant groups of round cellular sporocarps appear at the bases of the floating fronds. they are about a line in diameter when mature, and are of two kinds, one containing macrospores, the other microspores or antheridia. the first, when mature, hold a number of closely packed globular or oval sporangia of loose cellular tissue, attached to a central placenta. each of these sporangia contains a single macrospore, perfectly globular and smooth, with a dense outer membrane (exhibiting traces of lamination, and showing within an irregularly vacuolated or cellular structure, probably a prothallus). i cannot detect in it the peculiar pores which appear in the fossil specimens. each macrospore is about one-seventieth of an inch in diameter when mature. the sporocarps of the microspores contain a vastly greater number of minute sporangia, about one two-hundredths of an inch in diameter. these contain disc-like antheridia, or microspores of very minute size. the discs from kettle point and from the ohio black shale, and from the shale boulders of the chicago clays, are similar to the macrospores of _salvinia_, except that they have a thicker wall and are a little less in diameter, being about one-eightieth of an inch. the brazilian sporocarps are considerably larger than those of the modern _salvinia_, and the macrospores approach in size to those of the modern species, being one seventy-fifth of an inch in diameter. they also seem, like the modern species, to have thinner walls than those from canada, ohio, and chicago. no distinct indication has been observed in the fossil species of the inner sporangium of _salvinia_. possibly it was altogether absent, but more probably it is not preserved as a distinct structure. with reference to the microspores of _salvinia_, it is to be observed that the sporocarps, and the contained spores or antheridia, are very delicate and destitute of the dense outer wall of the macrospores. hence such parts are little likely to have been preserved in a fossil state; and in the erian shales, if present, they probably appear merely as flocculent carbonaceous matter not distinctly marked, or as minute granules not well defined, of which there are great quantities in some of the shales. the vegetation appertaining to the sporangites has not been distinctly recognised. i have, however, found in one of the brazilian specimens two sporocarps attached to what seems a fragment of a cellular frond, and numerous specimens of the supposed algæ, named _spirophyton_, are found in the shales, but there is no evidence of any connection of this plant with the _protosalvinia_. modern rhizocarps present considerable differences as to their vegetative parts. some, like _pilularia_, have simple linear leaves; others, like _marsilea_, have leaves in whorls, and cuneate in form; while others, like _azolla_ and _salvinia_, have frondose leaves, more or less pinnate in their arrangement. if we inquire as to fossils representing these forms of vegetation, we shall find that some of the plants to be noticed in the immediate sequel may have been nearly allied to the rhizocarps. in the mean time i may state that i have proposed the generic name _protosalvinia_ for these curious macrospores and their coverings, and have described in the paper in the "bulletin of the chicago academy of sciences," already quoted, five species which may be referred to this genus. these facts lead to inquiries as to the origin of the bituminous matter which naturally escapes from the rocks of the earth as petroleum and inflammable gas, or which may be obtained from certain shales in these forms by distillation. these products are compounds of carbon and hydrogen, and may be procured from recent vegetable substances by destructive distillation. some vegetable matters, also, are much richer in carbon and hydrogen than others, and it is a remarkable fact that the spores of certain cryptogamous plants are of this kind, as we see in the inflammable character of the dry spores of lycopodium; and we know that the slow putrefaction of such material underground effects chemical changes by which bituminous matter can be produced. there is, therefore, nothing unreasonable in the supposition advanced by prof. orton, that the spores so abundantly contained in the ohio black shales are important or principal sources of the bituminous matter which they contain. microscopic sections of this shale show that much of its material consists of the rich bituminous matter of these spores (fig. ). at the same time, while we may trace the bitumen of these shales, and of some beds of coal, to this cause, we must bear in mind that there are other kinds of bituminous rocks which show no such structures, and may have derived their combustible material from other kinds of vegetable matter, whether of marine or of land plants. we shall better understand this when we have considered the origin of coal. the macrospores above referred to may have belonged to humble aquatic plants mantling the surfaces of water or growing up from the bottom, and presenting little aërial vegetation. but there are other erian plants, as already mentioned, which, while of higher structure, may be of rhizocarpean affinities. one of these is the beautiful plant with whorls of wedge-shaped leaves, to which the name _sphenophyllum_ (see fig. ) has been given. plants referred to this genus have been described by lesquereux from the upper part of the siluro-cambrian,[ap] and a beautiful little species occurs in the erian shales of st. john, new brunswick.[aq] the genus is also continued, and is still more abundant, in the carboniferous. many years ago i observed, in a beautiful specimen collected by sir w. e. logan, in new brunswick, that the stem of this plant had an axis of reticulated and scalariform vessels, and an outer bark.[ar] renault and williamson have more recently obtained more perfect specimens, and the former has figured a remarkably complex triangular axis, containing punctate and barred vessels, and larger punctate vessels filling in its angles. outside of this there is a cellular inner bark, and this is surrounded by a thick fibrous envelope. that a structure so complex should belong to a plant so humble in its affinities is one of the strange anomalies presented by the old world, and of which we shall find many similar instances. the fruit of _sphenophyllum_ was borne in spikes, with little whorls of bracts or rudimentary leaves bearing round sporocarps. [ap] "american journal of science." [aq] dawson, "report on devonian plants," . [ar] "journal of the geological society," . [illustration: fig. .--_ptilophyton plumosum_ (lower carboniferous, nova scotia). natural size and magnified.] a second type of plant, which may have been rhizocarpean in its affinities, is that to which i have given the name _ptilophyton_.[as] it consists of beautiful feathery fronds, apparently bearing on parts of the main stem or petiole small rounded sporocarps. they are found abundantly in the middle erian of the state of new york, and also occur in scotland, while one species appears to occur in nova scotia, as high as the lower carboniferous (figs. , ). [as] _plumalina_ of hall. [illustration: fig. .--_ptilophyton thomsoni_ (scotland), _a_, impression of plant in vernation, _b_, branches conjecturally restored, _c_, branches of _lycopodites milleri_, on same slab.] these organisms have been variously referred to lycopods, to algæ, or to zoöphytes, but an extended comparison of american and scottish specimens has led me to the belief that they were aquatic plants, more likely to have been allied to rhizocarps than to any other group. some evidence of this will be given in a note appended to this chapter. [illustration: fig. .--_psilophyton princeps_, restored (lower erian, gaspé). _a_, fruit, natural size. _b_, stem, natural size, _c_, scalariform tissue of the axis, highly magnified. in the restoration, one side is represented in vernation and the other in fruit.] another genus, which i have named _psilophyton_[at] (figs. , ), may be regarded as a connecting link between the rhizocarps and the lycopods. it is so named from its resemblance, in some respects, to the curious parasitic lycopods placed in the modern genus _psilotum_. several species have been described, and they are eminently characteristic of the lower erian, in which they were first discovered in gaspé. the typical species, _psilophyton princeps_, which fills many beds of shale and sandstone in gaspé bay and the head of the neighbouring bay des chaleurs with its slender stems and creeping, cord-like rhizomes, may be thus described: [at] "journal of the geological society," vols, xv., xviii., and xix., "report on devonian plants of canada," . stems branching dichotomously, and covered with interrupted ridges. leaves rudimentary, or short, rigid, and pointed; in barren stems, numerous and spirally arranged; in fertile stems and branchlets, sparsely scattered or absent; in decorticated specimens, represented by a minute punctate scars. young branches circinate; rhizomata cylindrical, covered with hairs or ramenta, and having circular areoles irregularly disposed, giving origin to slender cylindrical rootlets. internal structure--an axis of scalariform vessels, surrounded by a cylinder of parenchymatous cells, and by an outer cylinder of elongated woody cells. fructification consisting of naked oval spore-cases, borne usually in pairs on slender, curved pedicels, either lateral or terminal. [illustration: fig. .--_sphenophyllum antiquum_ (erian, new brunswick). see pp. , .] this species was fully described by me in the papers referred to above, from specimens obtained from the rich exposures at gaspé bay, and which enabled me to illustrate its parts more fully, perhaps, than those of any other species of so great antiquity. in the specimens i had obtained i was able to recognise the forms of the rhizomata, stems, branches, and rudimentary leaves, and also the internal structure of the stems and rhizomata, and to illustrate the remarkable resemblance of the forms and structures to those of the modern _psilotum_. the fructification was, however, altogether peculiar, consisting of narrowly ovate sporangia, borne usually in pairs, on curved and apparently rigid petioles. under the microscope these sporangia show indications of cellular structure, and appear to have been membranous in character. in some specimens dehiscence appears to have taken place by a slit in one side, and, clay having entered into the interior, both walls of the spore-case can be seen. in other instances, being flattened, they might be mistaken for scales. no spores could be observed in any of the specimens, though in some the surface was marked by slight, rounded prominences, possibly the impressions of the spores within. this peculiar and very simple style of spore-case is also characteristic of other species, and gives to _psilophyton_ a very distinct generic character. these naked spore-cases may be compared to those of such lycopodiaceous plants as _psilotum_, in which the scales are rudimentary. they also bear some resemblance, though on a much larger scale, to the spore-cases of some erian ferns (_archæopteris_), to be mentioned in the sequel. on the whole, however, they seem most nearly related to the sporocarps of the rhizocarpeæ. [illustration: fig. .--_lepidodendron_ and _psilophyton_ (erian, new brunswick). a, _lepidodendron gaspianum_. b, c, _psilophyton elegans_.] _arthrostigma_, which is found in the same beds with psilophyton, was a plant of more robust growth, with better-developed, narrow, and pointed leaves, borne in a verticillate or spiral manner, and bearing at the ends of its branches spikes of naked sporocarps, apparently similar to those of _psilophyton_ but more rounded in form. the two genera must have been nearly related, and the slender branchlets of _arthrostigma_ are, unless well preserved, scarcely distinguishable from the stems of _psilophyton_.[au] [au] reports of the author on "devonian plants," "geological survey of canada," which see for details as to erian flora of northeastern america. if, now, we compare the vegetation of these and similar ancient plants with that of modern rhizocarps, we shall find that the latter still present, though in a depauperated and diminished form, some of the characteristics of their predecessors. some, like _pilularia_, have simple linear leaves; others, like _marsilea_, have leaves in verticils and cuneate in form; while others, like azolla and salvinia, have frondose leaves, more or less pinnate in their arrangement. the first type presents little that is characteristic, but there are in the erian sandstones and shales great quantities of filamentous and linear objects which it has been impossible to refer to any genus, and which might have belonged to plants of the type of _pilularia_. it is quite possible, also, that such plants as _psilophyton glabrum_ and _cordaites angustifolia_, of which the fructification is quite unknown, may have been allied to rhizocarps. with regard to the verticillate type, we are at once reminded of _sphenophyllum_ (fig. ), which many palæobotanists have referred to the _marsiliacæ_, though, like other palæozoic acrogens, it presents complexities not seen in its modern representatives. _s. primævum_ of lesquereux is found in the hudson river group, and my _s. antiquum_ in the middle erian. besides these, there are in the silurian and erian beds plants with verticillate leaves which have been placed with the annulariæ, but which may have differed from them in fructification. _annularia laxa_, of the erian, and _protannularia harknessii_, of the siluro-cambrian, may be given as examples, and must have been aquatic plants, probably allied to rhizocarps. it is deserving of notice, also, that the two best-known species of _psilophyton_ (_p. princeps_ and _p. robustius_), while allied to lycopods by the structure of the stem and such rudimentary foliage as they possess, are also allied, by the form of their fructification, to the rhizocarps, and not to ferns, as some palæobotanists have incorrectly supposed. a similar remark applies to _arthrostigma_; and the beautiful pinnately leaved _ptilophyton_ may be taken to represent that type of foliage as seen in modern rhizocarps, while the allied forms of the carboniferous which lesquereux has named _trochophyllum_, seem to have had sporocarps attached to the stem in the manner of _azolla_. the whole of this evidence, i think, goes to show that in the erian period there were vast quantities of aquatic plants, allied to the modern rhizocarps, and that the so-called _sporangites_ referred to in this paper were probably the drifted sporocarps and macrospores of some of these plants, or of plants allied to them in structure and habit, of which the vegetative organs have perished. i have shown that in the erian period there were vast swampy flats covered with _psilophyton_, and in similar submerged tracts near to the sea the _protosalvinia_ may have filled the waters and have given off the vast multitudes of macrospores which, drifted by currents, have settled in the mud of the black shales. we have thus a remarkable example of a group of plants reduced in modern times to a few insignificant forms, but which played a great role in the ancient palæozoic world. leaving the rhizocarps, we may now turn to certain other families of erian plants. the first to attract our attention in this age would naturally be the lycopods, the club-mosses or ground-pines, which in canada and the eastern states carpet the ground in many parts of our woods, and are so available for the winter decoration of our houses and public buildings. if we fancy one of these humble but graceful plants enlarged to the dimensions of a tree, we shall have an idea of a _lepidodendron_, or of any of its allies (figs. , ). these large lycopodiaceous trees, which in different specific and generic forms were probably dominant in the erian woods, resembled in general those of modern times in their fruit and foliage, except that their cones were large, and probably in most cases with two kinds of spores, and their leaves were also often very long, thus bearing a due proportion to the trees which they clothed. their thick stems required, however, more strength than is necessary in their diminutive successors, and to meet this want some remarkable structures were introduced similar to those now found only in the stems of plants of higher rank. the cells and vessels of all plants consist of thin walls of woody matter, enclosing the sap and other contents of these sacs and tubes, and when strength is required it is obtained by lining their interior with successive coats of the hardest form of woody matter, usually known as lignin. but while the walls remain thin, they afford free passage to the sap to nourish every part. if thickened all over, they would become impervious to sap, and therefore unsuited to one of their most important functions. these two ends of strength and permeability are secured by partial linings of lignin, leaving portions of the original wall uncovered. but this may be done in a great variety of ways. the most ancient of these contrivances, and one still continued in the world of plants, is that of the barred or scalariform vessel. this may be either square or hexagonal, so as to admit of being packed without leaving vacancies. it is strengthened by a thick bar of ligneous matter up each angle, and these are connected by cross-bars so as to form a framework resembling several ladders fastened together. hence the name _scalariform_, or ladder-like. now, in a modern lycopod there is a central axis of such barred vessels associated with simpler fibres or elongated cells. even in _sphenophyllum_ and _psilophyton_, already referred to as allied to rhizocarps,[av] there is such a central axis, and in the former rigidity is given to this by the vascular and woody elements being arranged in the form of a three-sided prism or three-rayed star. but such arrangements would not suffice for a tree, and hence in the arboreal lycopods of the erian age a more complex structure is introduced. the barred vessels were expanded in the first instance into a hollow cylinder filled in with pith or cellular tissue, and the outer rind was strengthened with greatly thickened cells. but even this was not sufficient, and in the older stems wedge-shaped bundles of barred tissue were run out from the interior, forming an external woody cylinder, and inside of the rind were placed bundles of tough bast fibres. thus, a stem was constructed having pith, wood, and bark, and capable of additions to the exterior of the woody wedges by a true exogenous growth. the plan is, in short, the same with that of the stems of the exogenous trees of modern times, except that the tissues employed are less complicated. the structures of these remarkable trees, and the manner in which they anticipate those of the true exogens of modern times, have been admirably illustrated by dr. williamson, of manchester. his papers, it is true, refer to these plants as existing in the carboniferous age, but there is every reason to believe that they were of the same character in the erian. the plan is the same with that now seen in the stems of exogenous phænogams, and which has long ceased to be used in those of the lycopods. in this way, however, large and graceful lycopodiaceous trees were constructed in the erian period, and constituted the staple of its forests. [av] first noticed by the author, "journal of geological society," ; but more completely by renault, "comptes rendus," . the roots of these trees were equally remarkable with their stems, and so dissimilar to any now existing that botanists were long disposed to regard them as independent plants rather than roots. they were similar in general structure to the stems to which they belonged, but are remarkable for branching in a very regular manner by bifurcation like the stems above, and for the fact that their long, cylindrical rootlets were arranged in a spiral manner and distinctly articulated to the root after the manner of leaves rather than of rootlets, and fitting them for growing in homogeneous mud or vegetable muck. they are the so-called _stigmaria_ roots, which, though found in the erian and belonging to its lycopodiaceous plants, attained to far greater importance in the carboniferous period, where we shall meet with them again. there were different types of lycopodiaceous plants in the erian. in addition to humble lycopods like those of our modern woods and great lepidodendra, which were exaggerated lycopods, there were thick-stemmed and less graceful species with broad rhombic scars (_leptophleum_), and others with the leaf-scars in vertical rows (_sigillaria_), and others, again, with rounded leaf-scars, looking like the marks on stigmaria, and belonging to the genus _cyclostigma_. thus some variety was given to the arboreal club-mosses of these early forests. (see fig. .) [illustration: fig. .--erian ferns (new brunswick), a, _aneimites obtusa_. c, _neuropteris polymorpha_. f, _sphenopteris pilosa_. n, _hymenophyllites subfurcatus_.] another group of plants which attained to great development in the erian age is that of the ferns or brackens. the oldest of these yet known are found in the middle erian. the _eopteris_ of saporta, from the silurian, at one time supposed to carry this type much further back, has unfortunately been found to be a mere imitative form, consisting of films of pyrites of leaf-like shapes, and produced by crystallisation. in the middle erian, however, more especially in north america, many species have been found (figs. to ).[aw] i have myself recorded more than thirty species from the middle erian of canada, and these belong to several of the genera found in the carboniferous, though some are peculiar to the erian. of the latter, the best known are perhaps those of the genus _archæopteris_ (fig. ), so abundant in the plant-beds of kiltorcan in ireland, as well as in north america. in this genus the fronds are large and luxuriant, with broad obovate pinnules decurrent, on the leaf-stalk, and with simple sac-like spore-cases borne on modified pinnæ. another very beautiful fern found with _archæopteris_ is that which i have named _platyphyllum_, and which grew on a creeping stem or parasitically on stems of other plants, and had marginal fructification.[ax] another very remarkable fern, which some botanists have supposed may belong to a higher group than the ferns, is megalopteris (fig. ). [aw] for descriptions of these ferns, see reports cited above. [ax] "reports on fossil plants of the devonian and upper silurian of canada," , &c. [illustration: fig. .--erian ferns (new brunswick), b, _cyclopteris valida_, and pinnule enlarged, d, _sphenopteris marginata_, and portion enlarged. e, _sphenopteris harttii_. g, _hymenophyllites curtilobus_. h, _hymenophyllites gersdorffii_, and portion enlarged. i, _alethopteris discrepans_, k, _pecopteris serrulata_, l, _pecopteris preciosa_. m, _alethopteris perleyi_.] [illustration: fig. .--_archæopteris jacksoni_, dawson (maine). an upper erian fern, _a_, _b_, pinnules showing venation.] [illustration: fig. .--an erian tree-fern. _caulopteris lockwoodi_, dawson, reduced. (from a specimen from gilboa, new york.)] some of the erian ferns attained to the dimensions of tree-ferns. large stems of these, which must have floated out far from land, have been found by newberry in the marine limestone of ohio (_caulopteris antiqua_ and _c. peregrina_, newberry),[ay] and prof. hall has found in the upper devonian of gilboa, new york, the remains of a forest of tree-ferns standing _in situ_ with their great masses of aërial roots attached to the soil in which they grew (_caulopteris lockwoodi_, dn.).[az] [ay] "journal of the geological society," . [az] _ibid._ [illustration: fig. .--_megalopteris dawsoni_, hartt (erian, new brunswick), _a_, fragment of pinna. _b_, point of pinnule, _c_, venation, (the midrib is not accurately given in this figure.)] these aërial roots introduce us to a new contrivance for strengthening the stems of plants by sending out into the soil multitudes of cord-like cylindrical roots from various heights on the stem, and which form a series of stays like the cordage of a ship. this method of support still continues in the modern tree-ferns of the tropics and the southern hemisphere. in one kind of tree-fern stem from the erian of new york, there is also a special arrangement for support, consisting of a series of peculiarly arranged radiating plates of scalariform vessels, not exactly like those of an exogenous stem, but doing duty for it (_asteropteris_)[ba] similar plants have been described from the erian of falkenberg, in germany, and of saalfeld, in thuringia, by goeppert and unger, and are referred to ferns by the former, but treated as doubtful by the latter,[bb] this peculiar type of tree-fern is apparently a precursor of the more exogenous type of _heterangium_, recently described and referred to ferns by williamson. here, again, we have a mechanical contrivance now restricted to higher plants appropriated by these old cryptogams. [ba] "journal of the geological society," london, . [bb] "sphenopteris refracta," goeppert; "flora des uebergangsgebirges." "cladoxylon mirabile," unger; "palæontologie des thuringer waldes." [illustration: fig. .--_calamites radiatus_ (erian, new brunswick).] the history of the ferns in geological time is remarkably different from that of the lycopods; for while the latter have long ago descended from their pristine eminence to a very humble place in nature, the former still, in the southern hemisphere at least, retain their arboreal dimensions and ancient dominance. [illustration: fig. .--asterophyllites (erian, new brunswick), a, asterophyllites latifolia. b, do., apex of stem (?) fruit, c, c^ , _a. scutigera_. d, _a. latifolia_, larger whorl of leaves. d^ , leaf.] the family of the _equisetaceæ_, or mare's-tails, was also represented by large species of _calamites_ and by _asterophyllites_ in the erian; but, as its headquarters are in the carboniferous, we may defer its consideration till the next chapter. (figs. , .) passing over these for the present, we find that the flowering plants are represented in the erian forests by at least two types of gymnosperms, that of _taxineæ_ or yews, and an extinct family, that of the _cordaites_ (figs. , ). the yew-trees are closely allied to the pines and spruces, and are often included with them in the family of _coniferæ_. they differ, however, in the habit of producing berries or drupe-like fruits instead of cones, and there is some reason to believe that this was the habit of the erian trees of this group, though their wood in some instances resembles rather that of the araucaria, or norfolk island pine, than that of the modern yews. these trees are chiefly known to us by their mineralised trunks, which are often found like drift-wood on modern sand-banks embedded in the erian sandstones or limestones. it often shows its structure in the most perfect manner in specimens penetrated by calcite or silica, or by pyrite, and in which the original woody matter has been resolved into anthracite or even into graphite. these trees have true woody tissues presenting that beautiful arrangement of pores or thin parts enclosed in cup-like discs, which is characteristic of the coniferous trees, and which is a great improvement on the barred tissue already referred to, affording a far more strong, tough, and durable wood, such as we have in our modern pines and yews (fig. ). [illustration: fig. .--_dadoxylon ouangondianum_, an erian conifer, a, fragment showing sternberg pith and wood; _a_, medullary sheath; _b_, pith; _c_, wood; _d_, section of pith, b, wood-cell; _a_, hexagonal areole; _b_, pore, _c_, longitudinal section of wood, showing, _a_, areolation, and _b_, medullary rays, d, transverse section, showing, _a_, wood-cells, and _b_, limit of layer of growth, (b, c, d, highly magnified.)] these primitive pines make their appearance in the middle erian, in various parts of america, as well as in scotland and germany, and they are represented by wood indicating the presence of several species. i have myself indicated and described five species from the erian of canada and the united states. from the fact that these trees are represented by drifted trunks embedded in sandstones and marine limestones, we may, perhaps, infer that they grew on the rising grounds of the erian land, and that their trunks were carried by river-floods into the sea. no instance has yet certainly occurred of the discovery of their foliage or fruit, though there are some fan-shaped leaves usually regarded as ferns which may have belonged to such trees. these in that case would have resembled the modern _gingko_ of china, and some of the fruits referred to the genus _cardiocarpum_ may have been produced by them. various names have been given to these trees. i have preferred that given by unger, _dadoxylon_, as being more non-committal as to affinities than the others.[bc] many of these trees had very long internal pith-cylinders, with curious transverse tubulæ, and which, when preserved separately, have been named _sternbergia_. [bc] _araucarites_, goeppert; _araucarioxylon_, kraus. allied to these trees, and perhaps intermediate between them and the _cycads_, were those known as _cordaites_ (fig. ), which had trunks resembling those of _dadoxylon_, but with still larger _sternbergia_ piths and an internal axis of scalariform vessels, surrounded by a comparatively thin woody cylinder. some of them have leaves over a foot in length, reminding one of the leaves of broad-leaved grasses or iridaceous plants. yet their flowers and fruit seem to have been more nearly allied to the yews than to any other plants (fig. ). their stems were less woody and their piths larger than in the true pines, and some of the larger-leaved species must have had thick, stiff branches. they are regarded as constituting a separate family, intermediate between pines and cycads, and, beginning in the middle devonian, they terminate in the permian, where, however, some of the most gigantic species occur. in so far as the form and structure of the leaves, stems, and fruit are concerned, there is marvellously little difference between the species found in the erian and the permian. they culminated, however, in the carboniferous period, and the coal-fields of southern france have proved so far the richest in their remains. [illustration: fig. .--_cordaites robbii_ (erian, new brunswick), _a_, group of young leaves. _b_, point of leaf, _c_, base of leaf, _d_. venation, magnified.] [illustration: fig. .--erian fruits, &c., some gymnospermous, and probably of _cordaites_ and taxine trees (st. john, new brunswick), a, _cardiocarpum cornutum_. b, _cardiocarpum acutum_. c, _cardiocarpum crampii_. d, _cardiocarpum baileyi_. e, _trigonocarpum racemosum_. e^ , e^ , fruits enlarged, f, _antholithes devonicus_. g, annularia acuminata, h, _asterophyllites acicularis_. h^ , fruit of the same, k, _cardiocarpum_ (? young of _a._), l, _pinnularia dispalans_ (probably a root).] lastly, a single specimen, collected by prof. james hall, of albany, at eighteen-mile creek, lake erie, has the structure of an ordinary angiospermous exogen, and has been described by me as _syringoxylon mirabile_.[bd] this unique example is sufficient to establish the fact of the existence of such plants at this early date, unless some accident may have carried a specimen from a later formation to be mixed with erian fossils. it is to be observed, however, that the non-occurrence of any similar wood in all the formations between the upper erian and the middle cretaceous suggests very grave doubt as to the authenticity of the specimen. i record the fact, waiting further discoveries to confirm it. of the character of the specimen which i have described i entertain no doubt. [bd] "journal of the geological society," vol. xviii. we shall be better able to realise the significance and relations of this ancient flora when we have studied that of the succeeding carboniferous. we may merely remark here on the fact that, in these forests of the devonian and in the marshes on their margins, we find a wonderful expansion of the now modest groups of rhizocarps and lycopods, and that the flora as a whole belongs to the highest group of cryptogams and the lowest of phænogams, so that it has about it a remarkable aspect of mediocrity. further, while there is evidence of some variety of station, there is also evidence of much equality of climate, and of a condition of things more resembling that of the insular climates of the temperate portions of the southern hemisphere than that of north america or europe at present. the only animal inhabitants of these devonian woods, so far as known, were a few species of insects, discovered by hartt in new brunswick, and described by dr. scudder. since, however, we now know that scorpions as well as insects existed in the silurian, it is probable that these also occurred in the erian, though their remains have not yet been discovered. all the known insects of the erian woods are allies of the shad-flies and grasshoppers (_neuroptera_ and _orthoptera_), or intermediate between the two. it is probable that the larvæ of most of them lived in water and fed upon the abundant vegetable matter there, or on the numerous minute crustaceans and worms. there were no land vertebrates, so far as known, but there were fishes (_dipterus_, etc.), allied to the modern barramunda or _ceratodus_ of australia, and with teeth suited for grinding vegetable food. it is also possible that some of the smaller plate-covered fishes (placoganoids, like _pterichthys_) might have fed on vegetable matter, and, in any case, if they fed on lower animals, the latter must have subsisted on plants. i mention these facts to show that the superabundant vegetation of this age, whether aquatic or terrestrial, was not wholly useless to animals. it is quite likely, also, that we have yet much to learn of the animal life of the erian swamps and woods. notes to chapter iii. i.--classification of sporangites. it is, of course, very unsatisfactory to give names to mere fragments of plants, yet it seems very desirable to have some means of arranging them. with respect to the organisms described above, which were originally called by me _sporangites_, under the supposition that they were sporangia rather than spores, this name has so far been vindicated by the discovery of the spore-cases belonging to them, so that i think it may still be retained as a provisional name; but i would designate the whole as _protosalviniæ_, meaning thereby plants with rhizocarpean affinities, though possibly when better understood belonging to different genera. we may under these names speak of their detached discs as macrospores and of their cellular envelopes as sporocarps. the following may be recognized as distinct forms: . _protosalvinia huronensis_, dawson, _syn._, _sporangites huronensis_, "report on erian flora of canada," .--macrospores, in the form of discs or globes, smooth and thick-walled, the walls penetrated by minute radiating pores. diameter about one one-hundredth of an inch, or a little more, when in situ several macrospores are contained in a thin cellular sporocarp, probably globular in form. from the upper erian, and perhaps lower carboniferous shales of kettle point, lake huron, of various places in the state of ohio, and in the shale boulders of the boulder clay of chicago and vicinity. first collected at kettle point by sir w. e. logan, and in ohio by prof. edward orton, and at chicago by dr. h. a. johnson and mr. b. w. thomas, also in new york by prof. j. m. clarke. the macrospores collected by mr. thomas from the chicago clays and shales conform closely to those of kettle point, and probably belong to the same species. some of them are thicker in the outer wall, and show the pores much more distinctly. these have been called by mr. thomas _s. chicagoensis_, and may be regarded as a varietal form. specimens isolated from the shale and mounted dry, show what seems to have been the hilum or scar of attachment better than those in balsam. sections of the kettle point shale show, in addition to the macrospores, wider and thinner shreds of vegetable matter, which i am inclined to suppose to be remains of the sporocarps. . _protosalvinia_ (_sporangites_) _braziliensis_, dawson, "canadian record of science," .--macrospores, round, smooth, a little longer than those of the last species, or about one seventy-fifth of an inch in diameter, enclosed in round, oval, or slightly reniform sporocarps, each containing from four to twenty-four macrospores. longest diameter of sporocarps three to six millimetres. structure of wall of sporocarps hexagonal cellular. some sporocarps show no macrospores, and may possibly contain microspores. the specimens are from the erian of brazil. discovered by mr. orville derby. the formation, according to mr. derby, consists of black shales below, about three hundred feet thick, and containing the fucoid known as spirophyton, and probably decomposed vegetable matter. above this is chocolate and reddish shale, in which the well-preserved specimens of protosalvinia occur. these beds are very widely distributed, and abound in _protosalvinia_ and _spirophyton_. . _protosalvinia_ (_sporangites_) _bilobata_, dawson, "canadian record of science," .--sporocarps, oval or reniform, three to six millimetres in diameter, each showing two rounded prominences at the ends, with a depression in the middle, and sometimes a raised neck or isthmus at one side connecting the prominences. structure of sporocarp cellular. some of the specimens indicate that each prominence or tubercle contained several macrospores. at first sight it would be easy to mistake these bodies for valves of _beyrichia_. found in the same formations with the last species, though, in so far as the specimens indicate, not precisely in the same beds. collected by mr. derby. . _protosalvinia clarkei_, dawson, _p. bilobata_, clarke, "american journal of science."--macrospores two-thirds to one millimetre in diameter. one, two, or three contained in each sporocarp, which is cellular. the macrospores have very thick walls with radiating tortuous tubes. unless this structure is a result of mineral crystallisation, these macrospores must have had very thick walls and must have resembled in structure the thickened cells of stone fruits and of the core of the pear, or the tests of the silurian and erian seeds known as _pachytheca_, though on a smaller scale. it is to be observed that bodies similar to these occur in the boghead earthy bitumen, and have been described by credner. i have found similar bodies in the so-called "stellar coal" of the coal district of pictou, nova scotia, some layers of which are filled with them. they occur in groups or patches, which seem to be enclosed in a smooth and thin membrane or sporocarp. it is quite likely that these bodies are generically distinct from _protosalvinia_. . _protosalvinia punctata_, newton, "geological magazine," new series, december d, vol. ii.--mr. newton has named the discs found in the white coal and tasmanite, _tasmanites_, the species being _tasmanites punctatus_, but as my name _sporangites_ had priority, i do not think it necessary to adopt this term, though there can be little doubt that these organisms are of similar character. the same remark may be made with reference to the bodies described by huxley and newton as occurring in the better-bed coal. in witham's "internal structure of fossil vegetables," , plate xi, are figures of lancashire cannel which shows _sporangites_ of the type of those in the erian shales. quekett, in his "report on the torbane hill mineral," , has very well figured similar structures from the methel coal and the lesmahagow cannel coal. these are the earliest publications on the subject known to me; and quekett, though not understanding the nature of the bodies he observed, holds that they are a usual ingredient in cannel coals. ii.--the nature and affinities of ptilophyton. (_lycopodites vanuxemii_ of "report on devonian and upper silurian plants," part i., page , _l. plumula_ of "report on lower carboniferous plants," page , plate i., figs. , , .) in the reports above referred to, these remarkable pinnate, frond-like objects were referred to the genus _lycopodites_, as had been done by goeppert in his description of the european species _lycopodites pennæformis_, which is very near to the american erian form. since , however, there have been many new specimens obtained, and very various opinions expressed as to their affinities. while hall has named some of them _plumalina_, and has regarded them as animal structures, allied to hydroids, lesquereux has described some of the carboniferous forms under the generic name _trochophyllum_, which is, however, more appropriate to plants with verticillate leaves which are included in this genus. before i had seen the publications of hall and lesquereux on the subject, i had in a paper on "scottish devonian plants"[be] separated this group from the genus _lycopodites_, and formed for it the genus _ptilophyton_, in allusion to the feather-like aspect of the species. my reasons for this, and my present information as to the nature of these plants, may be stated as follows: schimper, in his "palæontologie vegetale" (possibly from inattention to the descriptions or want of access to specimens), doubts the lycopodiaceous character of species of _lycopodites_ described in my published papers on plants of the devonian of america and in my report of . of these, _l. richardsoni_ and _l. matthewi_ are undoubtedly very near to the modern genus _lycopodium_. _l. vanuxemii_ is, i admit, more problematical; but schimper could scarcely have supposed it to be a fern or a fucoid allied to _caulerpa_ had he observed that both in my species and the allied _l. pennæformis_ of goeppert, which he does not appear to notice, the pinnules are articulated upon the stem, and leave scars where they have fallen off. when in belfast in , my attention was again directed to the affinities of these plants by finding in prof. thomson's collection a specimen from caithness, which shows a plant apparently of this kind, with the same long narrow pinna? or leaflets, attached, however, to thicker stems, and rolled up in a circinate manner. it seems to be a plant in vernation, and the parts are too much crowded and pressed together to admit of being accurately figured or described; but i think i can scarcely be deceived as to its true nature. the circinate arrangement in this case would favour a relationship to ferns; but some lycopodiaceous plants also roll themselves in this way, and so do the branches of the plants of the genus _psilophyton_. (fig. , _supra_.) [be] "canadian naturalist," . the specimen consists of a short, erect stem, on which are placed somewhat stout alternate branches, extending obliquely outward and then curving inward in a circinate manner. the lower ones appear to produce on their inner sides short lateral branchlets, and upon these, and also upon the curved extremities of the branches, are long, narrow, linear leaves placed in a crowded manner. the specimen is thus not a spike of fructification, but a young stem or branch in vernation, and which when unrolled would be of the form of those peculiar pinnate _lycopodites_ of which _l. vanuxemii_ of the american devonian and _l. pennæformis_ of the european lower carboniferous are the types, and it shows, what might have been anticipated from other specimens, that they were low, tufted plants, circinate in vernation. the short stem of this plant is simply furrowed, and bears no resemblance to a detached branch of lycopodites milleri which lies at right angles to it on the same slab. as to the affinities of the singular type of plants to which this specimen belongs, i may quote from my "report on the lower carboniferous plants of canada," in which i have described an allied species, _l. plumula_: "the botanical relations of these plants must remain subject to doubt, until either their internal structure or their fructification can be discovered. in the mean time i follow goeppert in placing them in what we must regard as the provisional genus _lycopodites_. on the one hand, they are not unlike the slender twigs of _taxodium_ and similar conifers, and the highly carbonaceous character of the stems gives some colour to the supposition that they may have been woody plants. on the other hand, they might, so far as form is concerned, be placed with algæ of the type of brongniart's _chondrites obtusus_, or the modern _caulerpa plumaria_. again, in a plant of this type from the devonian of caithness to which i have referred in a former memoir, the vernation seems to have been circinate, and schimper has conjectured that these plants may be ferns, which seems also to have been the view of shumard." on the whole, these plants are allied to lycopods rather than to ferns; and as they constitute a small but distinct group, known only, so far as i am aware, in the lower carboniferous and erian or devonian, they deserve a generic name, and i proposed for them in my "paper on scottish devonian plants," , that of _ptilophyton_, a name sufficiently distinct in sound from psilophyton, and expressing very well their peculiar feather-like habit of growth. the genus was defined as follows: "branching plants, the branches bearing long, slender leaves in two or more ranks, giving them a feathered appearance; vernation circinate. fruit unknown, but analogy would indicate that it was borne on the bases of the leaves or on modified branches with shorter leaves." the scottish specimen above referred to was named _pt. thomsoni_, and was characterised by its densely tufted form and thick branches. the other species known are: _pt. pennæformis_, goeppert, l. carboniferous; _pt. vanuxemii_, dawson, devonian; _pt. plumula_, dawson, l. carboniferous. shumard's _filicites gracilis_, from the devonian of ohio, and stur's _pinites antecedens_, from the lower carboniferous of silesia, may possibly belong to the same genus. the scottish specimen referred to is apparently the first appearance of this form in the devonian of europe. i have at a still later date had opportunities of studying considerable series of these plants collected by prof. williams, of cornell university, and prepared a note in reference to them for the american association, of which, however, only an abstract has been published. i have also been favoured by prof. lesquereux and mr. lacoe, of pittston, with the opportunity of studying the specimens referred to _trochophyllum_. prof. williams's specimens occur in a dark shale associated with remains of land-plants of the genera _psilophyton_. _rhodea_, &c., and also marine shells, of which a small species of _rhynchonella_ is often attached to the stems of the _ptilophyton_. thus these organisms have evidently been deposited in marine beds, but in association with land-plants. the study of the specimens collected by prof. williams develops the following facts: ( ) the plants are not continuous fronds, but slender stems or petioles, with narrow, linear leaflets attached in a pinnate manner. ( ) the pinnules are so articulated that they break off, leaving delicate transverse scars, and the lower parts of the stems are often thus denuded of pinnæ for the length of one or more inches. ( ) the stems curve in such a manner as to indicate a circinate vernation. ( ) in a few instances the fronds were observed to divide dichotomously toward the top; but this is rare. ( ) there are no indications of cells in the pinnules; but, on the other hand, there is no appearance of fructification unless the minute granules which roughen some of the sterns are of this nature. ( ) the stems seem to have been lax and flexuous, and in some instances they seem to have grown on the petioles of ferns preserved with them in the same beds. ( ) the frequency of the attachment of small brachiopods to the specimens of _ptilophyton_ would seem to indicate that the plant stood erect in the water. ( ) some of the specimens show so much carbonaceous matter as to indicate that the pinnules were of considerable consistency. all these characters are those rather of an aquatic plant than of an animal organism or of a land-plant. the specimens communicated by prof. lesquereux and mr. lacoe are from the lower carboniferous, and evidently represent a different species with similar slender pitted stems, often partially denuded of pinnules below; but the pinnules are much broader and more distant. they are attached by very narrow bases, and apparently tend to lie on a plane, though they may possibly have been spirally arranged. on the same slabs are rounded sporangia or macrospores like those of _lepidodendron_, but there is no evidence that these belonged to _trochophyllum_. on the stems of this plant, however, there are small, rounded bodies apparently taking the places of some of the pinnules. these may possibly be spore-cases; but they may be merely imperfectly developed pinnules. still the fact that similar small granules appear on the stems of the devonian species, favours the idea that they may be organs of fructification. the most interesting discovery, however, which results from the study of mr. lacoe's specimens, is that the pinnules were cylindrical and hollow, and probably served to float the plant. this would account for many of the peculiarities in the appearance and mode of occurrence of the devonian _ptilophyton_, which are readily explained if it is supposed to be an aquatic plant, attaching itself to the stems of submerged vegetable remains and standing erect in the water by virtue of its hollow leaves. it may well, however, have been a plant of higher organisation than the algæ, though no doubt cryptogamous. the species of _ptilophyton_ will thus constitute a peculiar group of aquatic plants, belonging to the devonian and lower carboniferous periods, and perhaps allied to lycopods and pillworts in their organisation and fruit, but specially distinguished by their linear leaves serving as floats and arranged pinnately on slender stems. the only species yet found within the limits of canada is _pt. plumula_, found by dr. honeyman in the lower carboniferous of nova scotia; but as _pt. vanuxemii_ abounds in the erian of new york, it will no doubt be found in canada also. iii.--tree-ferns of the erian period. as the fact of the occurrence of true tree-ferns in rocks so old as the middle erian or devonian has been doubted in some quarters, the following summary is given from descriptions published in the "journal of the geological society of london" ( and ), where figures of the species will be found: of the numerous ferns now known in the middle and upper devonian of north america, a great number are small and delicate species, which were probably herbaceous; but there are other species which may have been tree-ferns. little definite information, however, has, until recently, been obtained with regard to their habit of growth. the only species known to me in the devonian of europe is the _caulopteris peachii_ of salter, figured in the "quarterly journal of the geological society" for . the original specimen of this i had an opportunity of seeing in london, through the kindness of mr. etheridge, and have no doubt that it is the stem of a small arborescent fern, allied to the genus _caulopteris_, of the coal formation. in my paper on the devonian of eastern america ("quarterly journal of the geological society," ), i mentioned a plant found by mr. richardson at perry, as possibly a species of _megaphyton_, using that term to denote those stems of tree-ferns which have the leaf-scars in two vertical series; but the specimen was obscure, and i have not yet obtained any other. more recently, in , prof. hall placed in my hands an interesting collection from gilboa, new york, and madison county, new york, including two trunks surrounded by aërial roots, which i have described as _psaronius textilis_ and _p. erianus_, in my "revision of the devonian flora," read before the royal society.[bf] in the same collection were two very large petioles, _rhachiopteris gigantea_ and _r. palmata_, which i have suggested may have belonged to tree-ferns. [bf] abstract in "proceedings of the royal society," may, ; also "report on erian plants of canada," . my determination of the species of _psaronius_, above mentioned, has recently been completely confirmed by the discovery on the part of mr. lockwood, of gilboa, of the upper part of one of these stems, with its leaf-scars preserved and petioles attached, and also by some remarkable specimens obtained by prof. newberry, of new york, from the corniferous limestone of ohio, which indicate the existence there of three species of tree-ferns, one of them with aërial roots similar to those of the gilboa specimens. the whole of these specimens dr. newberry has kindly allowed me to examine, and has permitted me to describe the gilboa specimen, as connected with those which i formerly studied in prof. hall's collections. the specimens from ohio he has himself named, but allows me to notice them here by way of comparison with the others. i shall add some notes on specimens found with the gilboa ferns. it may be further observed that the gilboa specimens are from a bed containing erect stumps of tree-ferns, in the chemung group of the upper devonian, while those from ohio are from a marine limestone, belonging to the lower part of the middle devonian. . _caulopteris lockwoodi_, dawson.--trunk from two to three inches in diameter, rugose longitudinally. leaf-scars broad, rounded above, and radiatingly rugose, with an irregular scar below, arranged spirally in about five ranks; vascular bundles not distinctly preserved. petioles slender, much expanded at the base, dividing at first in a pinnate manner, and afterwards dichotomously. ultimate pinnæ with remains of numerous, apparently narrow pinnules. this stem is probably the upper part of one or other of the species of _psaronius_ found in the same bed (_p. erianus_, dawson, and _p. textilis_, dawson).[bg] it appears to have been an erect stem embedded in situ in sandstone, and preserved as a cast. the stem is small, being only two inches, or a little more, in diameter. it is coarsely wrinkled longitudinally, and covered with large leaf-scars, each an inch in diameter, of a horseshoe-shape. the petioles, five of which remain, separate from these scars with a distinct articulation, except at one point near the base, where probably a bundle or bundles of vessels passed into the petiole. they retain their form at the attachment to the stem, but a little distance from it they are flattened. they are inflated at the base, and somewhat rapidly diminish in size. the leaf-scars vary in form, and are not very distinct, but they appear to present a semicircular row of pits above, largest in the middle. from these there proceed downward a series of irregular furrows, converging to a second and more obscure semicircle of pits, within or below which is the irregular scar or break above referred to. the attitude and form of the petioles will be seen from fig. , _supra_. [bg] memoir on devonian flora, "proceedings of the royal society," may, . the petioles are broken off within a few inches of the stem; but other fragments found in the same beds appear to show their continuation, and some remains of their foliage. one specimen shows a series of processes at the sides, which seem to be the remains of small pinnæ, or possibly of spines on the margin of the petiole. other fragments show the division of the frond, at first in a pinnate manner, and subsequently by bifurcation; and some fragments show remains of pinnules, possibly of fertile pinnules. these are very indistinct, but would seem to show that the plant approached, in the form of its fronds and the arrangement of its fructification, to the cyclopterids of the sub-genus _aneimites_, one of which (_aneimites acadica_), from the lower carboniferous of nova scotia, i have elsewhere described as probably a tree-fern,[bh] the fronds were evidently different from those of _archæopteris_[bi] a genus characteristic of the same beds, but of very different habit of growth. this accords with the fact that there is in prof. hall's collection a mass of fronds of _cyclopteris_ (_archæopteris_) jacksoni, so arranged as to make it probable that the plant was an herbaceous fern, producing tufts of fronds on short stems in the ordinary way. the obscurity of the leaf-scars may render it doubtful whether the plant above described should be placed in the genus _caulopteris_ or in _stemmatopteris_; but it appears most nearly allied to the former. the genus is at present, of course, a provisional one; but i have thought it only justice to the diligent labours of mr. lockwood to name this curious and interesting fossil _caulopteris lockwoodi_. [bh] "quarterly journal of the geological society," . [bi] the genus to which the well-known _cyclopteris_ (_adiantites_) _hibernicus_ of the devonian of ireland belongs. i have elsewhere remarked on the fact that trunks, and petioles, and pinnules of ferns are curiously dissociated in the devonian beds--an effect of water-sorting, characteristic of a period in which the conditions of deposition were so varied. another example of this is, that in the sandstones of gaspé bay, which have not as yet afforded any example of fronds of ferns, there are compressed trunks, which mr. lockwood's specimens allow me at least to conjecture may have belonged to tree-ferns, although none of them are sufficiently perfect for description. mr. lockwood's collection includes specimens of _psaronius textilis_; and in addition to these there are remains of erect stems somewhat different in character, yet possibly belonging to the higher parts of the same species of tree-fern. one of these is a stem crushed in such a manner that it does not exhibit its form with any distinctness, but surrounded by smooth, cylindrical roots, radiating from it in bundles, proceeding at first horizontally, and then curving downward, and sometimes terminating in rounded ends. they resemble in form and size the aërial roots of _psaronius erianus_; and i believe them to be similar roots from a higher part of the stem, and some of them young and not prolonged sufficiently far to reach the ground. this specimen would thus represent the stem of _p. erianus_ at a higher level than those previously found. we can thus in imagination restore the trunk and crown of this once graceful tree-fern, though we have not the detail of its fronds. mr. lockwood's collections also contain a specimen of the large fern-petiole which i have named _rhachiopteris punctata_. my original specimen was obtained by prof. hall from the same horizon in new york. that of mr. lockwood is of larger size, but retains no remains of the frond. it must have belonged to a species quite distinct from _caulopteris lockwoodi_, but which may, like it, have been a tree-fern. . _caulopteris antiqua_, newberry.--this is a flattened stem, on a slab of limestone, containing brachiopods, trilobites, &c., of the corniferous limestone. it is about eighteen inches in length, and three and a half inches in average breadth. the exposed side shows about twenty-two large leaf-scars arranged spirally. each leaf, where broken off, has left a rough fracture; and above this is a semicircular impression of the petiole against the stem, which, as well as the surface of the bases of the petioles, is longitudinally striated or tuberculated. the structures are not preserved, but merely the outer epidermis, as a coaly film. the stem altogether much resembles _caulopteris peachii_, but is of larger size. it differs from _c. lockwoodi_ in the more elongated leaf-bases, and in the leaves being more remotely placed; but it is evidently of the same general character with that species. . _caulopteris_ (_protopteris_) _peregrina_, newberry.--this is a much more interesting species than the last, as belonging to a generic or subgeneric form not hitherto recognised below the carboniferous, and having its minute structure in part preserved. the specimens are, like the last, on slabs of marine limestone of the corniferous formation, and flattened. one represents an upper portion of the stem with leaf-scars and remains of petioles; another a lower portion, with aërial roots. the upper part is three inches in diameter, and about a foot in length, and shows thirty leaf-scars which are about three-fourths of an inch wide, and rather less in depth. the upper part presents a distinct rounded and sometimes double marginal line, sometimes with a slight depression in the middle. the lower part is irregular, and when most perfect shows seven slender vascular bundles, passing obliquely downward into the stem. the more perfect leaf-bases have the structure preserved, and show a delicate, thin-walled, oval parenchyma, while the vascular bundles show scalariform vessels with short bars in several rows, in the manner of many modern ferns. some of the scars show traces of the hippocrepian mark characteristic of _protopteris_; and the arrangement of the vascular bundles at the base of the scars is the same as in that genus, as are also the general form and arrangement of the scars. on careful examination, the species is indeed very near to the typical _p. sternbergii_, as figured by corda and schimper.[bj] [bj] corda, "beiträge," pl. , copied by schimper, pl. . the genus _protopteris_ of sternberg, though the original species (_p. punctata_) appears as a _lepidodendron_ in his earlier plate (plate ), and as a _sigillaria_ (_s. punctata_) in brongniart's great work, is a true tree-fern; and the structure of one species (_p. cottai_) has been beautifully figured by corda. the species hitherto described are from the carboniferous and permian. the second specimen of this species represents a lower part of the stem. it is thirteen inches long and about four inches in diameter, and is covered with a mass of flattened aërial roots lying parallel to each other, in the manner of the _psaronites_ of the coal-formation and of _p. erianus_ of the upper erian or devonian. . _asteropteris noveboracensis_, gen. and sp. n.--the genus _asteropteris_ is established for stems of ferns having the axial portion composed of vertical radiating plates of scalariform tissue embedded in parenchyma, and having the outer cylinder composed of elongated cells traversed by leaf-bundles of the type of those of _zygopteris_. the only species known to me is represented by a stem · centimetres in diameter, slightly wrinkled and pitted externally, perhaps by traces of aërial roots which have perished. the transverse section shows in the centre four vertical plates of scalariform or imperfectly reticulated tissue, placed at right angles to each other, and united in the middle of the stem. at a short distance from the centre, each of these plates divides into two or three, so as to form an axis of from ten to twelve radiating plates, with remains of cellular tissue filling the angular interspaces. the greatest diameter of this axis is about · centimetre. exterior to the axis the stem consists of elongated cells, with somewhat thick walls, and more dense toward the circumference. the walls of these cells present a curious reticulated appearance, apparently caused by the cracking of the ligneous lining in consequence of contraction in the process of carbonization. embedded in this outer cylinder are about twelve vascular bundles, each with a dumb-bell-shaped group of scalariform vessels enclosed in a sheath of thick-walled fibres. each bundle is opposite to one of the rays of the central axis. the specimen shows about two inches of the length of the stem, and is somewhat bent, apparently by pressure, at one end. this stem is evidently that of a small tree-fern of a type, so far as known to me, not before described,[bk] and constituting a very complex and symmetrical form of the group of palæozoic ferns allied to the genus _zygopteris_ of schimper. the central axis alone has a curious resemblance to the peculiar stem described by unger ("devonian flora of thuringia") under the name of _cladoxylon mirabile_; and it is just possible that this latter stem may be the axis of some allied plant. the large aërial roots of some modern tree-ferns of the genus _angiopteris_ have, however, an analogous radiating structure. [bk] prof. williamson, to whom i have sent a tracing of the structure, agrees with me that it is new. the specimen is from the collection of berlin h. wright, esq., of penn yan, new york, and was found in the portage group (upper erian) of milo, new york, where it was associated with large petioles of ferns and trunks of _lepidodendra_, probably _l. chemungense_ and _l. primævum_. the occurrence of this and other stems of tree-ferns in marine beds has recently been illustrated by the observation of prof. a. agassiz that considerable quantities of vegetable matter can be dredged from great depths in the sea on the leeward side of the caribbean islands. the occurrence of these trunks further connects itself with the great abundance of large petioles (_rhachiopteris_) in the same beds, while the rarity of well-preserved fronds is explained by the coarseness of the beds, and also by the probably long maceration of the plant-remains in the sea-water. in connection with this i may refer to the remarkable facts recently stated by williamson[bl] respecting the stems known as heterangium and _lyginodendron_. it would seem that these, while having strong exogenous peculiarities, are really stems of tree-ferns, thus placing this family in the same position of advancement with the lycopods and equisetaceæ of the coal period. [bl] "proceedings of the royal society," january , . iv.--on erian trees of the genus dadoxylon, unger. (_araucarites_ of goeppert, _araucarioxylon_ of kraus.) large woody trunks, carbonised or silicified, and showing wood-cells with hexagonal areoles having oval pores inscribed in them, occur abundantly in some beds of the middle erian of america, and constitute the most common kind of fossil wood all the way to the trias. they have in the older formations, generally, several rows of pores on each fibre, and medullary rays composed of two or more series of cells, but become more simple in these respects in the permian and triassic series. the names _araucarites_ and _araucarioxylon_ are perhaps objectionable, inasmuch as they suppose affinities to _araucaria_ which may not exist. unger's name, which is non-committal, is therefore, i think, to be preferred. in my "acadian geology," and in my "report on the geology of prince edward island," i have given reasons for believing that the foliage of some at least of these trees was that known as _walchia_, and that they may have borne nutlets in the manner of taxine trees (_trigonocarpum_, &c). grand d'eury has recently suggested that some of them may have belonged to _cordaites_, or to plants included in that somewhat varied and probably artificial group. the earliest discovery of trees of this kind in the erian of america was that of matthew and hartt, who found large trunks, which i afterwards described as _dadoxylon ouangondianum_, in the erian sandstone of st. john, new brunswick, hence named by those geologists the "dadoxylon sandstone." a little later, similar wood was found by prof. hall and prof. newberry in the hamilton group of new york and ohio, and the allied wood of the genus _ormoxylon_ was obtained by prof. hall in the portage group of the former state. these woods proved to be specifically distinct from that of st. john, and were named by me _d. halli_, _d. newberryi_, and _ormoxylon erianum_. the three species of _dadoxylon_ agreed in having composite medullary rays, and would thus belong to the group _palæoxylon_ of brongniart. in the case of _ormoxylon_ this character could not be very distinctly ascertained, but the medullary rays appeared to be simple. i am indebted to prof. j. m. clarke, of amherst college, massachusetts, for some well-preserved specimens of another species from the genesee shale of canandaigua, new york. they show small steins or branches, with a cellular pith surrounded with wood of coniferous type, showing two to three rows of slit-formed, bordered pores in hexagonal borders. the medullary sheath consists of pseudo-scalariform and reticulated fibres; but the most remarkable feature of this wood is the structure of the medullary rays, which are very frequent, but short and simple, sometimes having as few as four cells superimposed. this is a character not before observed in coniferous trees of so great age, and allies this middle erian form with some carboniferous woods which have been supposed to belong to _cordaites_ or _sigillaria_. in any case this structure is new, and i have named the species _dadoxylon clarkii_, after its discoverer. the specimens occur, according to prof. clarke, in a calcareous layer which is filled with the minute shells of _styliola fissurella_ of hall, believed to be a pteropod; and containing also shells of _goniatites_ and _gyroceras_. the stems found are only a few inches in diameter, but may be branches of larger trees. it thus appears that we already know five species of coniferous trees of the genus _dadoxylon_ in the middle erian of america, an interesting confirmation of the facts otherwise known as to the great richness and variety of this ancient flora. the late prof. goeppert informed me that he had recognised similar wood in the devonian of germany, and there can be no doubt that the fossil wood discovered by hugh miller in the old red sandstone of scotland, and described by salter and mcnab, is of similar character, and probably belongs to the genus _dadoxylon_. thus this type of coniferous tree seems to have been as well established and differentiated into species in the middle devonian as in the succeeding carboniferous. i may here refer to the fact that the lower limit of the trees of this group coincides, in america, with the upper limit of those problematical trees which in the previous chapter i have named protogens (_nematophyton_, _celluloxlyon_,[bm] _nematoxylon_[bn]), though _aporoxylon_ of unger extends, in thuringia, up to the upper devonian (cypridina schists). [bm] "journal of the geological society," may, . [bn] _ibid._, vol. xix, . v.--scottish devonian plants of hugh miller and others. (edinburgh geological society, .) previously to the appearance of my descriptions of devonian plants from north america, hugh miller had described forms from the devonian of scotland, similar to those for which i proposed the generic name _psilophyton_; and i referred to these in this connection in my earliest description of that genus.[bo] he had also recognised what seemed to be plants allied to lycopods and conifers. mr. peach and mr. duncan had made additional discoveries of this kind, and sir j. hooker and mr. salter had described some of these remains. more recently messrs. peach, carruthers, and mcnab have worked in this field, and still later[bp] messrs. jack and etheridge have summed up the facts and have added some that are new. [bo] "journal of the geological society," london, . [bp] _ibid._, . the first point to which i shall refer, and which will lead to the other matters to be discussed, is the relation of the characteristic _lepidodendron_ of the devonian of eastern america, _l. gaspianum_, to _l. nothum_ of unger and of salter. at the time when i described this species i had not access to scottish specimens of _lepidodendron_ from the devonian, but these had been well figured and described by salter, and had been identified with _l. nothum_ of unger, a species evidently distinct from mine, as was also that figured and described by salter, whether identical or not with unger's species. in i had for the first time an opportunity to study scottish specimens in the collection of mr. peach; and on the evidence thus afforded i stated confidently that these specimens represented a species distinct from _l. gaspianum_, perhaps even generically so.[bq] it differs from _l. gaspianum_ in its habit of growth by developing small lateral branches instead of bifurcating, and in its foliage by the absence or obsolete character of the leaf-bases and the closely placed and somewhat appressed leaves. if an appearance of swelling at the end of a lateral branch in one specimen indicates a strobile of fructification, then its fruit was not dissimilar from that of the canadian species in its position and general form, though it may have differed in details. on these grounds i declined to identify the scottish species with _l. gaspianum_. the lepidodendron from the devonian of belgium described and figured by crepin,[br] has a better claim to such identification, and would seem to prove that this species existed in europe as well as in america. i also saw in mr. peach's collection in some fragments which seemed to me distinct from salter's species, and possibly belonging to _l. gaspianum_.[bs] [bq] "report on devonian plants of canada," . [br] "observations sur quelques plantes fossiles des dépôts devoniens." [bs] "proceedings of the geological society of london," march, . in the earliest description of _psilophyton_ i recognised its probable generic affinity with miller's "dichotomous plants," with salter's "rootlets," and with goeppert's _haliserites dechenianus_, and stated that i had "little doubt that materials exist in the old red sandstone of scotland for the reconstruction of at least one species of this genus." since, however, miller's plants had been referred to coniferous roots, and to fucoids, and goeppert's _haliserites_ was a name applicable only to fucoids, and since the structure and fruit of my plants placed them near to lycopods, i was under the necessity of giving them a special generic name, nor could i with certainty affirm their specific identity with any european species. the comparison of the scottish specimens with woody rootlets, though incorrect, is in one respect creditable to the acumen of salter, as in almost any state of preservation an experienced eye can readily perceive that branchlets of _psilophyton_ must have been woody rather than herbaceous, and their appearance is quite different from that of any true algæ. the type of _psilophyton_ is my _p. princeps_, of which the whole of the parts and structures are well known, the entire plant being furnished in abundance and in situ in the rich plant-beds of gaspé. a second species, _p. robustius_, has also afforded well-characterised fructification. _p. elegans_, whose fruit appears as "oval scales," no doubt bore sac-like spore-cases resembling those of the other species, but in a different position, and perfectly flattened in the specimens procured. the only other canadian species, _p. glabrum_, being somewhat different in appearance from the others, and not having afforded any fructification, must be regarded as uncertain. the generic characters of the first three species may be stated as follows: stems dichotomous, with rudimentary subulate leaves, sometimes obsolete in terminal branchlets and fertile branches; and in decorticated specimens represented only by punctiform scars. young branches circinate. rhizomata cylindrical, with circular root-areoles. internal structure of stem, an axis of scalariform vessels enclosed in a sheath of imperfect woody tissue and covered with a cellular bark more dense externally. fruit, naked sac-like spore-cases, in pairs or clusters, terminal or lateral. the scottish specimens conform to these characters in so far as they are known, but not having as yet afforded fruit or internal structure, they cannot be specifically determined with certainty. more complete specimens should be carefully searched for, and will no doubt be found. in belgium, m. crepin has described a new species from the upper devonian of condroz under the name _p. condrusianum_ ( ). it wants, however, some of the more important characters of the genus, and differs in having a pinnate ramification, giving it the aspect of a fern. in a later paper ( ) the author considers this species distinct from _psilophyton_, and proposes for it a new generic name _rhacophyton_. the characters given by mr. carruthers, in his paper of , for the species _p. dechenianum_, are very few and general: "lower branches short and frequently branching, giving the plant an oblong circumscription." yet even these characters do not apply, so far as known, to miller's fucoids or salter's rootlets or goeppert's _haliserites_. they merely express the peculiar mode of branching already referred to in salter's _lepidodendron nothum_. the identification of the former plants with the _lepidodendron_ and _lycopodites_, indeed, rests only on mere juxtaposition of fragments, and on the slight resemblance of the decorticated ends of the branches of the latter plants to _psilophyton_. it is contradicted by the obtuse ends of the branches of the _lepidodendron_ and _lycopodites_, and by the apparently strobilaceous termination of some of them. salter's description of his _lepidodendron nothum_ is quite definite, and accords with specimens placed in my hands by mr. peach: "stems half an inch broad, tapering little, branches short; set on at an acute angle, blunt at their terminations. leaves in seven to ten rows, very short, not a line long, and rather spreading than closely imbricate." these characters, however, in so far as they go, are rather those of the genus _lycopodites_ than of _lepidodendron_, from which this plant differs in wanting any distinct leaf-bases, and in its short, crowded leaves. it is to be observed that they apply also to salter's _lycopodites milleri_, and that the difference of the foliage of that species may be a result merely of different state of preservation. for these reasons i am disposed to place these two supposed species together, and to retain for the species the name _lycopodites milleri_. it may be characterised by the description above given, with merely the modification that the leaves are sometimes nearly one-third of an inch long and secund (fig. , _supra_, lower figure). decorticated branches of the above species may no doubt be mistaken for _psilophyton_, but are nevertheless quite distinct from it, and the slender branching dichotomous stems, with terminations which, as miller graphically states, are "like the tendrils of a pea," are too characteristic to be easily mistaken, even when neither fruit nor leaves appear. with reference to fructification, the form of _l. milleri_ renders it certain that it must have borne strobiles at the ends of its branchlets, or some substitute for these, and not naked spore-cases like those of _psilophyton_. the remarkable fragment communicated by sir philip egerton to mr. carruthers,[bt] belongs to a third group, and has, i think, been quite misunderstood. i am enabled to make this statement with some confidence, from the fact that the reverse or counterpart of sir philip's specimen was in the collection of sir wyville thomson, and was placed by him in my hands in . it was noticed in my paper on "new devonian plants," in the "journal of the geological society of london," and referred to my genus _ptilophyton_, as stated above under section ii., page _et seq._ [bt] "journal of botany," . mr. salter described, in ,[bu] fragments of fossil wood from the scottish devonian, having the structure of dadoxylon, though very imperfectly preserved; and prof. mcnab has proposed[bv] the generic name _palæopitys_ for another specimen of coniferous wood collected by hugh miller, and referred to by him in the "testimony of the rocks." from prof. mcnab's description, i should infer that this wood may, after all, be generically identical with the woods usually referred to dadoxylon of unger (_araucarioxylon_ of kraus). the description, however, does not mention the number and disposition of the rows of pores, nor the structure of the medullary rays, and i have not been able to obtain access to the specimens themselves. i have described five species of dadoxylon from the middle and upper erian of america, all quite distinct from the lower carboniferous species. there is also one species of an allied genus, ormoxylon. all these have been carefully figured, and it is much to be desired that the scottish specimens should be re-examined and compared with them. [bu] "journal of the london geological society." [bv] "transactions of the edinburgh botanical society," . messrs. jack and etheridge have given an excellent summary of our present knowledge of the devonian flora of scotland, in the journal of the london geological society ( ). from this it would appear that species referable to the genera _calamities_, _lepidodendron_, _lycopodites_, _psilophyton_, _arthrostigma_, _archæopteris_, _caulopteris_, _palæopitys_, _araucarioxylon_, and _stigmaria_ have been recognised. the plants described by these gentlemen from the old red sandstone of callender, i should suppose, from their figures and descriptions, to belong to the genus _arthrostigma_, rather than to psilophyton. i do not attach any importance to the suggestions referred to by them, that the apparent leaves may be leaf-bases. long leaf-bases, like those characteristic of _lepidofloyos_, do not occur in these humbler plants of the devonian. the stems with delicate "horizontal processes" to which they refer may belong to _ptilophyton_ or to _pinnularia_. in conclusion, i need scarcely say that i do not share in the doubts expressed by some british palæontologists as to the distinctness of the devonian and carboniferous floras. in eastern america, where these formations are mutually unconformable, there is, of course, less room for doubt than in ireland and in western america, where they are stratigraphically continuous. still, in passing from the one to the other, the species are for the most part different, and new generic forms are met with, and, as i have elsewhere shown, the physical conditions of the two periods were essentially different.[bw] [bw] "reports on devonian plants and lower carboniferous plants of canada." it is, however, to be observed that since--as stur and others have shown--_calamities radiatus_, and other forms distinctively devonian in america, occur in europe in the lower carboniferous, it is not unlikely that the devonian flora, like that of the tertiary, appeared earlier in america. it is also probable, as i have shown in the "reports" already referred to, that it appeared earlier in the arctic than in the temperate zone. hence an arctic or american flora, really devonian, may readily be mistaken for lower carboniferous by a botanist basing his calculations on the fossils of temperate europe. even in america itself, it would appear, from recent discoveries in virginia and ohio, that certain devonian forms lingered longer in those regions than farther to the northeast;[bx] and it would not be surprising if similar plants occurred in later beds in devonshire or in the south of europe than in scotland. still, these facts, properly understood, do not invalidate the evidence of fossil plants as to geological age, though errors arising from the neglect of them are still current. [bx] andrews, "palæontology of ohio," vol. ii.; meek, "fossil plants from western virginia," philosophical society, washington, . vi.--geological relations of some plant-bearing beds of eastern canada. ("report on erian plants," .) the gaspé sandstones have been fully described by sir w. e. logan, in his "report on the geology of canada," . he there assigns to them a thickness of seven thousand and thirty-six feet, and shows that they rest conformably on the upper silurian limestones of the lower helderberg group (ludlow), and are in their turn overlaid unconformably by the conglomerates which form the base of the carboniferous rocks of new brunswick. i shall add here merely a few remarks on points in their physical character connected with the occurrence of plants in them. _prototaxites_ (_nematophyton_) _logani_ and other characteristic lower erian plants occur in the base of the sandstones at little gaspé. this fact, along with the occurrence, as stated in my paper of , of rhizomes of _psilophyton_ preserving their scalariform structure, in the upper part of the marine upper silurian limestones,[by] proves the flora of the devonian rocks to have had its beginning at least in the previous geological period, and to characterise the lower as well as the upper beds of the devonian series. in this connection i may state that, from their marine fossils, as well as their stratigraphical arrangement, sir w. e. logan and mr. billings regard the lower portions of the gaspé sandstones as the equivalents of the oriskany sandstone of new york. on the other hand, the great thickness of this formation, the absence of lower devonian fossils from its upper part, and the resemblance of the upper beds to those of the newer members of the devonian elsewhere, render it probable that the gaspé sandstones, though deficient in the calcareous members of the system, seen farther to the westward, represent the whole of the devonian period. [by] the marine fossils of these beds have been determined by mr. billings. they are upper silurian, with an intermixture of lower devonian in the upper part. fragments of _nematophyton_ occur in beds of the same age in the bay des chaleurs, at cape bon ami. the gaspé sandstones, as their name imports, are predominantly arenaceous, and often coarsely so, the sandstones being frequently composed of large grains and studded with quartz-pebbles. grey and buff are prevalent colours, but red beds also occur, more especially in the upper portion. there are also interstratified shaly beds, sometimes occurring in groups of considerable thickness, and associated with fine-grained and laminated argillaceous sandstone, the whole having in many places the lithological aspect of the coal-measures. at one place, near the middle of the series, there is a bed of coal from one inch to three inches in thickness, associated with highly bituminous shales abounding in remains of plants, and also containing fragments of crustaceans and fishes (_pterygotus_, _ctenacanthus ?_ &c). the beds connected with this coal are grey sandstones and grey and dark shales, much resembling those of the ordinary coal formation. the coal is shining and laminated, and both its roof and floor consist of laminated bituminous shale with fragments of _psilophyton_. it has no true under-clay, and has been, i believe, a peaty mass of rhizomes of _psilophyton_. it occurs near tar point, on the south side of gaspé bay, a place so named from the occurrence of a thick dyke of trap holding petroleum in its cavities. the coal is of considerable horizontal extent, as in its line of strike a similar bed has been discovered on the douglas river, about four miles distant. it has not been recognised on the north side of the bay, though we find there beds, probably on very nearly the same horizon, holding _psilophyton_ in situ. as an illustration of one of the groups of shaly beds, and of the occurrence of roots of _psilophyton_, i may give the following sectional list of beds seen near "watering brook," on the north shore of the bay. the order is descending: ft. in. . grey sandstones and reddish pebbly sandstone of great thickness . bright-red shale . grey shales with stems of _psilophyton_, very abundant but badly preserved . grey incoherent clay, slickensided, and with many rhizomes and roots of _psilophyton_ . hard grey clay or shale, with fragments and roots of _psilophyton_ . red shale . grey and reddish crumbling sandstone groups of beds similar to the above, but frequently much more rich in fossils, occur in many parts of the section, and evidently include fossil soils of the nature of under-clays, on which little else appears to have grown than a dense herbage of _psilophyton_, along with plants of the genus _arthrostigma_. in addition to these shaly groups, there are numerous examples of beds of shale of small thickness included in coarse sandstones, and these beds often occur in detached fragments, as if the remnants of more continuous layers partially removed by currents of water. it is deserving of notice that nearly all these patches of shale are interlaced with roots or stems of _psilophyton_, which sometimes project beyond their limits into the sandstone, as if the vegetable fibres had preserved the clay from removal. in short, these lines of patches of shale seem to be remnants of soils on which _psilophyton_ has flourished abundantly, and which have been partially swept away by the currents which deposited the sand. some of the smaller patches may even be fragments of tough swamp soils interwoven with roots, drifted by the agency of the waves or possibly by ice; such masses are often moved in this way on the borders of modern swamps on the sea-coast. the only remaining point connected with local geology to which i shall allude is the admirable facilities afforded by the gaspé coast both for ascertaining the true geological relations of the beds, and for studying the devonian plants, as distinctly exposed on large surfaces of rock. on the coast of the river st. lawrence, at cape rozier and its vicinity, the lower silurian rocks of the quebec group are well exposed, and are overlaid unconformably by the massive upper silurian limestones of cape gaspé, which rise into cliffs six hundred feet in height, and can be seen filled with their characteristic fossils on both sides of the cape. resting upon these, and dipping at high angles toward gaspé bay, are the devonian sandstones, which are exposed in rugged cliffs slightly oblique to their line of strike, along a coast-line of ten miles in length, to the head of the bay. on the opposite side of the bay they reappear; and, thrown into slight undulations by three anticlinal curves, occupy a line of coast fifteen miles in length. the perfect manner in which the plant-bearing beds are exposed in these fine natural sections may serve to account for the completeness with which the forms and habits of growth of the more abundant species can be described. in the bay des chaleurs, similar rocks exist with some local variations. in the vicinity of campbellton are calcareous and magnesian breccia or agglomerate, hard shales, conglomerates and sandstones of lower devonian age. the agglomerate and lower shales contain abundant remains of fishes of the genera _cephalaspis_, _coccosteus_, _ctenacanthus_, and _homacanthus_, and also fragments of _pterygotus_. the shales and sandstones abound in remains of _psilophyton_, with which are _nematophyton_, _arthrostigma_, and _leptophleum_ of the same species found in the lower devonian of gaspé bay. these beds near campbellton dip to the northward, and the restigouche river here occupies a synclinal, for on the opposite side, at bordeaux quarry, there are thick beds of grey sandstone dipping to the southward, and containing large silicified trunks of prototaxites, in addition to _psilophyton_. these beds are all undoubtedly lower erian, but farther to the eastward, on the north side of the river, there are newer and overlying strata. these are best seen at scaumenac bay, opposite dalhousie, between cape florissant and maguacha point, where they consist of laminated and fine-grained sandstone, with shales of grey colours, but holding some reddish beds at top, and overlaid unconformably by a great thickness of lower carboniferous red conglomerate and sandstone. in these beds numerous fossil fishes have been found, among which mr. whiteaves recognises species of _pterichthys_, _glyptolepis_, _cheirolepis_, &c. with these are found somewhat plentifully four species of fossil ferns, all of upper erian types, of which one is peculiar to this locality; but the others are found in the upper erian of perry, in maine, or in the cat skill group of new york. in order that distinct notions may be conveyed as to the geological horizons of the species, i may state that the typical devonian or erian series of canada and new york may be divided in descending order into-- . the chemung group, including the chemung and portage sandstones and shales. . the hamilton group, including the genesee, hamilton, and marcellus shales. . the corniferous limestone and its associated beds. the oriskany sandstone. as the corniferous limestone, which is the equivalent of the lower carboniferous limestone in the carboniferous period, is marine, and affords scarcely any plants, we may, as is usually done for like purposes in the carboniferous, group it with the oriskany under the name lower erian. the hamilton rocks will then be middle erian, and the chemung group upper erian. in the present state of our knowledge, the series may be co-ordinated with the rocks of gaspé, new brunswick, and maine, as in the following table: | new york | gaspé | southern | coast subdivisions. | and | and bay des | new | of | western canada.| chaleurs. | brunswick. | maine. --------------+----------------+--------------+--------------+----------- upper | chemung | upper |mispec group. | perry devonian or | group. | sandstones. | shale, |sandstones. erian. | |long cove, &c.| sandstone, | | | scauminac | and | | | beds. |conglomerate. | | | | | middle | hamilton | middle | little r. | devonian or | group. | sandstones. | group | erian. | | bois brulé, | (including | | | cape oiseau, | cordaite | | | &c. | shales and | | | | dadoxylon | | | | sandstone).| | | | | lower | corniferous | lower | lower | devonian or | and | sandstones. |conglomerates,| erian. | oriskany | gaspé basin, | &c. | | groups. | little gaspé,| | | | &c. | | | | campbellton | | | | beds. | | --------------+----------------+--------------+--------------+----------- it may be proper, before closing this note, to state the reasons which have induced me to suggest in the following pages the use of the term "erian," as equivalent to "devonian," for the great system of formations intervening between the upper silurian and the lower carboniferous in america. i have been induced to adopt this course by the following considerations: . the great area of undisturbed and unaltered rocks of this age, including a thickness in some places of eighteen thousand feet, and extending from east to west through the northern states of the union and western canada for nearly seven hundred miles, while it spreads from north to south from the northern part of michigan far into the middle states, is undoubtedly the most important devonian area now known to geologists. . this area has been taken by all american geologists as their typical devonian region. it is rich in fossils, and these have been thoroughly studied and admirably illustrated by the new york and canadian surveys. . the rocks of this area surround the basin of lake erie, and were named, in the original reports of the new york survey, the "_erie division_" . great difficulties have been experienced in the classification of the european devonian, and the uncertainties thus arising have tended to throw doubt on the results obtained in america in circumstances in which such difficulties do not occur. these reasons are, i think, sufficient to warrant me in holding the great _erie division_ of the new york geologists as the typical representative of the rocks deposited between the close of the upper silurian and the beginning of the carboniferous period, and to use the term erian as the designation of this great series of deposits as developed in america, in so far at least as their flora is concerned. in doing so, i do not wish to introduce a new name merely for the sake of novelty; but i hope to keep before the minds of geologists the caution that they should not measure the erian formations of america, or the fossils which they contain, by the comparatively depauperated representatives of this portion of the geological scale in the devonian of western europe. vii.--on the relations of the so-called "ursa stage" of bear island with the palæozoic flora of north america. the following note is a verbatim copy of that published by me in , and the accuracy of which has now been vindicated by the recent observations of nathorst: the plants catalogued by dr. heer, and characterising what he calls the "ursa stage," are in part representatives of those of the american flora which i have described as the "lower carboniferous coal-measures" (subcarboniferous of dana), and whose characteristic species, as developed in nova scotia, i noticed in the "journal of the geological society" in (vol. xv.). dr. heer's list, however, includes some upper devonian forms; and i would suggest that either the plants of two distinct beds, one lower carboniferous and the other upper devonian, have been near to or in contact with each other and have been intermixed, or else that in this high northern latitude, in which (for reasons stated in my "report on the devonian flora"[bz]) i believe the devonian plants to have originated, there was an actual intermixture of the two floras. in america, at the base of the carboniferous of ohio, a transition of this kind seems to occur; but elsewhere in northeastern america the lower carboniferous plants are usually unmixed with the devonian. [bz] "geological survey of canada," . dr. heer, however, proceeds to identify these plants with those of the american chemung, and even with those of the middle devonian of new brunswick, as described by me--a conclusion from which i must altogether dissent, inasmuch as the latter belong to beds which were disturbed and partially metamorphosed before the deposition of the lowest carboniferous or "subcarboniferous" beds. dr. heer's error seems to have arisen from want of acquaintance with the rich flora of the middle devonian, which, while differing in species, has much resemblance in its general facies, and especially in its richness in ferns, to that of the coal-formation. to geologists acquainted with the stratigraphy and the accompanying animal fossils, dr. heer's conclusions will of course appear untenable; but they may regard them as invalidating the evidence of fossil plants; and for this reason it is, i think, desirable to give publicity to the above statements. i consider the british equivalent of the lower coal-measures of eastern america to be the lower limestone shales, the _tweedian group_ of mr. tate ( ), but which have sometimes been called the "calciferous sandstone" (a name preoccupied for a cambrian group in america). this group does not constitute "beds of passage" to the devonian, more especially in eastern america, where the lower coal-formation rests unconformably on the devonian, and is broadly distinguished by its fossils. the above notes would not have been extended to so great length, but for the importance of the erian flora as the precursor of that of the carboniferous, and the small amount of attention hitherto given to it by geologists and botanists. chapter iv. the carboniferous flora--culmination of the acrogens--formation of coal. ascending from the erian to the carboniferous system, so called because it contains the greatest deposits of anthracite and bituminous coal, we are still within the limits of the palæozoic period. we are still within the reign of the gigantic club-mosses, cordaites, and taxine pines. at the close of the erian there had been over the whole northern hemisphere great changes of level, accompanied by active volcanic phenomena, and under these influences the land flora seems to have much diminished. at length all the old erian species had become extinct, and their place was supplied by a meagre group of lycopods, ferns, and pines of different species from those of the preceding erian. this is the flora of the lower carboniferous series, the tweedian of england, the horton series of nova scotia, the lower coal-measures of virginia, the culm of germany. but the land again subsided, and the period of the marine limestone of the lower carboniferous was introduced. in this the older flora disappeared, and when the land emerged we find it covered with the rich flora of the coal-formation proper, in which the great tribes of the lycopods and cordaites attained their maxima, and the ferns were continued as before, though under new generic and specific forms. [illustration: fig. .--foliage from the coal-formation, _a_, _alethopteris lonchitica_, fern (moose river). _b_, _sphenophyllum schlotheimii_ (pietou). _c_, _lepidodendron binerve_ (sydney), _d_, _asterophyllites foliosa_ (_?_) (sydney). _e_, _cordaites_ (joggins). _f_, _neuropteris rarinervis_, fern (sydney). _g_, _odontopteris subcuneata_, fern (sydney).] there is something very striking in this succession of a new plant world without any material advance. it is like passing in the modern world from one district to another, in which we see the same forms of life, only represented by distinct though allied species. thus, when the voyager crosses the atlantic from europe to america, he meets with pines, oaks, birches, poplars, and beeches of the same genera with those he had left behind; but the species are distinct. it is something like this that meets us in our ascent into the carboniferous world of plants. yet we know that this is a succession in time, that all our old erian friends are dead and buried long ago, and that these are new forms lately introduced (fig. ). conveying ourselves, then, in imagination forward to the time when our greatest accumulations of coal were formed, and fancying that we are introduced to the american or european continent of that period, we find ourselves in a new and strange world. in the devonian age, and even in the succeeding lower carboniferous, there was in the interior of america a wide inland sea, with forest belts clinging to its sides or clothing its islands. but in the coal period this inland sea had given place to vast swampy flats, and which, instead of the oil-bearing shales of the erian, were destined to produce those immense and wide-spread accumulations of vegetable matter which constitute our present beds of bituminous and anthracite coal. the atmosphere of these great swamps is moist and warm. their vegetation is most exuberant, but of forms unfamiliar to modern eyes, and they swarm with insects, millipedes, and scorpions, and with batrachian reptiles large and small, among which we look in vain for representatives of the birds and beasts of the present day. [illustration: fig. .--_sigillariæ_, restored. a, _sigillaria brownii_. b, _sigillaria elegans_.] [illustration: fig. .--_sigillaria lorwayana_, dawson. _a_, zones of fruit-scars. _b_, leaf-scar enlarged, _c_, fruit-scar enlarged. see appended note.] [illustration: fig. .--stem of _sigillaria brownii_. reduced. natural size.] [illustration: fig. .--two ribs of _sigillaria brownii_.] [illustration: fig. .--portion of lower part of stem of _s. brownii_. natural size.] prominent among the more gigantic trees of these swampy forests are those known to us as _sigillariæ_ (fig. ). they have tall, pillar-like trunks, often several feet in diameter, ribbed like fluted columns, but in the reverse way, and spreading at the top into a few thick branches, which are clothed with long, grass-like leaves. they resemble in some respects the lepidodendra of the erian age, but are more massive, with ribbed instead of scaly trunks, and longer leaves. if we approach one of them more closely, we are struck with the regular ribs of its trunk, dotted with rows of scars of fallen leaves, from which it receives its name _sigillaria_, or seal-tree (figs. - ). if we cut into its stem, we find that, instead of the thin bark and firm wood with which we are familiar in our modern trees, it has a hard external rind, then a great thickness of cellular matter with rope-like bands of fibres, constituting an inner bark, while in the centre is a firm, woody axis of comparatively small diameter, and somewhat intermediate in its structures between that of the lepidodendra and those of the cycads and the taxine conifers. thus a great stem, five feet in diameter, may consist principally of cellular and bast fibres with very little true woody matter. the roots of this tree are perhaps its most singular feature. they usually start from the stem in four main branches, then regularly bifurcate several times, and then run out into great cylindrical cables, running for a long distance, and evidently intended to anchor the plant firmly in a soft and oozy soil. they were furnished with long, cylindrical rootlets placed regularly in a spiral manner, and so articulated that when they dropped off they left regular rounded scars. they are, in short, the _stigmariæ_, which we have already met with in the erian (figs. , ). in fig. i have endeavoured to restore these strange trees. it is not wonderful that such plants have caused much botanical controversy. it was long before botanists could be convinced that their roots are properly roots at all, and not stems of some aquatic plant. then the structure of their stems is most puzzling, and their fruit is an enigma, for while some have found connected with them cones supposed to resemble those of lycopods, others attribute to them fruits like those of yew-trees. for years i have been myself gathering materials from the rich coal-formation deposits of nova scotia in aid of the solution of these questions, and in the mean time dr. williamson, of manchester, and renault and other botanists in france, have been amassing and studying stores of specimens, and it is still uncertain who may finally be the fortunate discoverer to set all controversies at rest. my present belief is, that the true solution consists in the fact that there are many kinds of _sigillariæ_. while in the modern forests of america and europe the species of any of our ordinary trees, as oaks, birches, or maples, may almost be counted on one's fingers, schimper in his vegetable palæontology enumerates about eighty species of carboniferous _sigillariæ_; and while on the one hand many of these are so imperfectly known that they may be regarded as uncertain, on the other hand many species must yet remain to be discovered.[ca] now, in so vast a number of species there must be a great range of organisation, and, indeed, it has already been attempted to subdivide them into several generic groups. the present state of the question appears to me to be this, that in these _sigillariæ_ we have a group divisible into several forms, some of which will eventually be classed with the lepidodendra as lycopods, while others will be found to be naked-seeded phænogams, allied to the pines and cycads, and to a remarkable group of trees known as _cordaites_, which we must shortly notice. [ca] in a recent memoir (berlin, ) stur has raised the number of species in one subdivision of the _sigillariæ_ (the _favulariæ_) to forty-seven! [illustration: fig. .--_stigmaria_ root, seen from above, showing its regular divisions. from "acadian geology".] [illustration: fig. .--portion of bark of _stigmaria_, showing scars of attachment of rootlets.] before considering other forms of carboniferous vegetation, let us glance at the accumulation of coal, and the agency of the forests of _sigillariæ_ therein. let us imagine, in the first instance, such trees as those represented in the figures, growing thickly together over vast swampy flats, with quantities of undergrowth of ferns and other plants beneath their shade, and accumulating from age to age in a moist soil and climate a vast thickness of vegetable mould and trunks of trees, and spores and spore-cases, and we have the conditions necessary for the growth of coal. many years ago it was observed by sir william logan that in the coal-field of south wales it was the rule with rare exceptions that, under every bed of coal, there is a bed of clay filled with roots of the _stigmaria_, already referred to as the root of _sigillaria_. this discovery has since been extended to all the coal-fields of europe and america, and it is a perfectly conclusive fact as regards the origin of coal. each of these "under-clays," as they are called, must, in fact, have been a soil on which grew, in the first instance, sigillariæ and other trees having stigmaria-roots. thus, the growth of a forest of _sigillariæ_ was the first step toward the accumulation of a bed of coal. more than this, in some of the coarser and more impure coals, where there has been sufficient earthy matter to separate and preserve impressions of vegetable forms, we can see that the mass of the coal is made up of flattened _sigillariæ_, mixed with vegetable _débris_ of all kinds, including sometimes vast quantities of lepidodendroid spores, and the microscopic study of the coal gives similar results (fig. ). further, on the surfaces of many coals, and penetrating the shales or sandstones which form their roofs, we find erect stumps of sigillaria and other trees, showing that the accumulation of the coal terminated as it had begun, by a forest-growth. i introduce here a section of a few of the numerous beds of coal exposed in the cliffs of the south joggins, in nova scotia, in illustration of these facts. we can thus see how in the slowly subsiding areas of the coal-swamps successive beds of coal were accumulated, alternating with beds of sandstone and shale (figs. , ). for other details of this kind i must refer to papers mentioned in the sequel. [illustration: fig. .--vegetable tissues from coal. _a_, _sigillaria_ and _cordaites_. _calamodendron_.] returning to the more special subject of this work, i may remark that the lepidodendroid trees and the ferns, both the arborescent and herbaceous kinds, are even more richly represented in the carboniferous than in the preceding erian, i must, however, content myself with merely introducing a few representatives of some of the more common kinds, in an appended note, and here give a figure of a well-known lower carboniferous lepidodendron, with its various forms of leaf-bases, and its foliage and fruit (fig. ), and a similar illustration of an allied generic form, that known as _lepidophloios_[cb] (fig. ). [cb] for full descriptions of these, see "acadian geology." [illustration: fig. .--beds associated with the main coal (s. joggins, nova scotia). , shale and sandstone--plants with _spirorbis_ attached; rain-marks (?). ( , sandstone and shale, eight feet--erect _calamites_; , gray sandstone, seven feet; , gray shale, four feet--an erect coniferous (?) tree, rooted on the shale, passes up through fifteen feet of the sandstones and shale.) , gray sandstone, four feet. , gray shale, six inches--prostrate and erect trees, with rootlets, leaves, _naiadites_, and _spirorbis_ on the plants. , main coal-seam, five feet of coal in two seams. , underclay, with rootlets.] another group which claims our attention is that of the _calamites_. these are tall, cylindrical, branchless stems, with whorls of branchlets, bearing needle-like leaves and spreading in stools from the base, so as to form dense thickets, like southern cane-brakes (fig. ). they bear, in habit of growth and fructification, a close relation to our modern equisetums, or mare's-tails, but, as in other cases we have met with, are of gigantic size and comparatively complex structure. their stems, in cross-section, show radiating bundles of fibres, like those of exogenous woods, yet the whole plan of structure presents some curious resemblances to the stems of their humble successors, the modern mare's-tails. it would seem, from the manner in which dense brakes of these _calamites_ have been preserved in the coal-formation of nova scotia, that they spread over low and occasionally inundated flats, and formed fringes on the seaward sides of the great sigillaria forests. in this way they no doubt contributed to prevent the invasion of the areas of coal accumulation by the muddy waters of inundations, and thus, though they may not have furnished much of the material of coal, they no doubt contributed to its purity. many beautiful plants of the genera asterophyllites and _annularia_ are supposed to have been allied to the _calamites_, or to have connected them with the _rhizocarps_. the stems and fruit of these plants have strong points of resemblance to those of _sphenophyllum_, and the leaves are broad, and not narrow and angular like those of the true _calamites_ (fig. ). [illustration: fig. .--erect _sigillaria_, standing on a coal-seam (s. joggins, nova scotia).] [illustration: fig. .--_lepidodendron corrugatum_, dawson, a tree characteristic of the lower carboniferous, a, restoration. b, leaf, natural size, c, cone and branch, d, branch and leaves, e. various forms of leaf-areoles. f, _sporangium_, i, l, m, bark, with leaf-scars, n, bark, with leaf-scars of old stem, o, decorticated stem (_knorria_).] [illustration: fig. .--_lepidophloios acadianus_, dawson, a lepidodendroid tree of the coal-formation, a, restoration. b, portion of bark (two thirds natural size), c, ligneous surface of the same, f, cone (two thirds natural size). g, leaf (natural, size), k, portion of woody cylinder, showing outer and inner series of vessels magnified, l, scalariform vessels (highly magnified), m, various forms of leaf-scars and leaf-bases (natural size).] [illustration: fig. .--_asterophyllites_, _sphenophyllum_, and _annularia_. a, _asterophyllites trinerne_. a^ , leaf enlarged, b, _annularia sphenophylloides_. b^ , leaf enlarged, c, _sphenophyllum erosum_. c^ , leaflet enlarged. c^ , scalariform vessel of _sphenophyllum_. d, _pinnularia ramosissima_, probably a root.] no one has done more than my friend dr. williamson, of manchester, to illustrate the structure of calamites, and he has shown that these plants, like other cryptogams of the carboniferous, had mostly stems with regular fibrous wedges, like those of exogens. the structure of the stem is, indeed, so complex, and differs so much in different stages of growth, and different states of preservation, that we are in danger of falling into the greatest confusion in classifying these plants. sometimes what we call a calamite is a mere cast of its pith showing longitudinal striæ and constrictions at the nodes. sometimes we have the form of the outer surface of the woody cylinder, showing longitudinal ribs, nodes, and marks of the emission of the branchlets. sometimes we have the outer surface of the plant covered with a smooth bark showing flat ribs, or almost smooth, and having at the nodes regular articulations with the bases of the verticillate branchlets, or on the lower part of the stem the marks of the attachment of the roots. the calamites grew in dense clumps, budding off from one another, sometimes at different levels, as the mud or sand accumulated about their stems, and in some species there were creeping rhizomata or root-stocks (figs. to ). [illustration: fig. .--_calamites_. a, _c. suckovii_. b, _c. cistii_. (from "acadian geology.")] [illustration: fig. .--erect _calamites_, with roots attached (nova scotia).] [illustration: fig. .--node of _c. cistii_, with long leaves (nova scotia).] but all calamites were not alike in structure. in a recent paper[cc] dr. williamson describes three distinct structural types. what he regards as typical calamites has in its woody zone wedges of barred vessels, with thick bands of cellular tissue separating them. a second type, which he refers to _calamopitus_, has woody bundles composed of reticulated or multiporous fibres, with their porous sides parallel to the medullary rays, which are better developed than in the previous form. the intervening cellular masses are composed of elongated cells. this is a decided advance in structure, and is of the type of those forms having the most woody and largest stems, which brongniart named _calamodendron_ (fig. ). a third form, to which dr. williamson seems to prefer to assign this last name, has the tissue of the woody wedges barred, as in the first, but the medullary rays are better developed than in the second. in this third form the intermediate tissue, or primary medullary rays, is truly fibrous, and with secondary medullary rays traversing it. my own observations lead me to infer that there was a fourth type of calamitean stem, less endowed with woody matter, and having a larger fistulous or cellular cavity than any of those described by dr. williamson. [cc] "memoirs of the philosophical society," manchester, -' . [illustration: fig. .--erect _calamites_ (_c. suckovii_), showing the mode of growth of new stems (_b_), and different forms of the ribs (_a_, _c_). (pictou, nova scotia.) half natural size.] there is every reason to believe that all these various and complicated stems belonged to higher and nobler types of mare's-tails than those of the modern world, and that their fructification was equisetaceous and of the form known as _calamostachys_. we have already seen that noble tree-ferns existed in the erian period, and these were continued, and their number and variety greatly extended, in the carboniferous. in regard to the structure of their stems, and the method of supporting these by aërial roots, the tree-ferns of all ages have been nearly alike, and the form and structure of the leaves, except in some comparatively rare and exceptional types, has also been much the same. any ordinary observer examining a collection of coal-formation ferns recognises at once their kinship to the familiar brackens of our own time. their fructification is, unfortunately, rarely preserved, so that we are not able, in the case of many species, to speak confidently of their affinities with modern forms; but the knowledge of this subject has been constantly extending, and a sufficient amount of information has been obtained to enable us to say something as to their probable relationships. (figs. to .) [illustration: fig. .--stems of _calamodendron_ and tissues magnified (nova scotia), _a_, _b_, casts of axis in sandstone, with woody envelope (reduced). _c_, _d_, woody tissue (highly magnified).] the families into which modern ferns are divided are, it must be confessed, somewhat artificial, and in the case of fossil ferns, in which the fructification is for the most part wanting, it is still more so, depending in great part on the form and venation of the divisions of the fronds. of about eight families into which modern ferns are divided, seven are found in a fossil state, and of these, four at least, the _cyathaceæ_, the _ophioglosseæ_, the _hymenophyllaceæ_, and the _marattiaceæ_, go back to the coal-formation.[cd] [cd] mr. r. kidston has recently described very interesting forms of fern fructification from the coal-formation of great britain, and much has been done by european palæobotanists, and also by lesquereux and fontaine in america. [illustration: fig. .--group of coal-formation ferns, a, _odontopteris subcuneata_ (bunbury), b, _neuropteris cordata_ (brongniart). c, _alethopteris lonchitica_ (brongniart). d, _dictyopteris obliqua_ (bunbury). e, _phyllopteris antiqua_ (dawson), magnified; e^ , natural size, f, _neuropteris cyclopteroides_ (dawson).] [illustration: fig. .--_alethopteris grandis_ (dawson). middle coal-formation of nova scotia.] [illustration: fig. .--_cyclopteris_ (_aneimites_) _acadica_ (dawson), a tree-fern of the lower carboniferous. _a_, pinnules. _b_, fragment of petiole. _c_, remains of fertile pinnules.] [illustration: fig. .--_sphenopteris latior_, dawson. coal-formation, _a_, pinnule magnified, with traces of fructification.] [illustration: fig. .--fructification of palæozoic ferns, _a_, thecæ of _archæopteris_ (erian). _b_, theca of _senftenbergia_ (carboniferous). _c_, thecæ of _asterotheca_ (carboniferous).] [illustration: fig. .--tree-ferns of the carboniferous. a, _megaphyton magnificum_, dawson, restored. b, leaf-scar of the same, two thirds natural size. b^ , row of leaf-scars, reduced. c, _palæopteris harttii_, scars half natural size. d, _acadica_, scars half natural size.] some of these ferns have the more complex kind of spore-case, with a jointed, elastic ring. it is to be observed, however, that those forms which have a simple spore-case, either netted or membranous, and without annulus, are most common in the devonian and lowest carboniferous. some of the forms in these old rocks are somewhat difficult to place in the system. of these, the species of _archæopteris_, of the upper and middle erian, are eminent as examples. this type, however, scarcely extends as high as the coal-formation.[ce] some of the tree-ferns of the carboniferous present very remarkable features. one of these, of the genus _megaphyton_, seems to have two rows of great leaves, one at each side of the stem, which was probably sustained by large bundles of aërial roots (fig. ). [ce] the pretty little ferns of the genus _botrychium_ (moonwort), so common in american and european woods, seem to be their nearest modern allies. in the carboniferous, as in the erian, there are leaves which have been referred to ferns, but are subject to doubt, as possibly belonging to broad-leaved taxine trees allied to the gingko-tree of china. one of these, represented in fig. , has been found in the coal-formation of nova scotia, and referred to the doubtful genus _noeggerathia_. fontaine has proposed for similar leaves found in virginia the new generic name _saportea_. [illustration: fig. .--_noeggerathia disbar_ (half natural size).] ferns, as might be inferred from their great age, are at the present time dispersed over the whole world; but their headquarters, and the regions to which tree-ferns are confined, are the more moist climates of the tropics and of the southern hemisphere. the coal-swamps of the northern hemisphere seem to have excelled even these favoured regions of the present world as a paradise for ferns. i have already stated that the carboniferous constitutes the headquarters of the _cordaites_ (fig. ), of which a large number of species have been described, both in europe and america. we sometimes, though rarely, find their stems showing structure. in this case we have a large cellular pith, often divided by horizontal partitions into flat chambers, and constituting the objects which, when detached, are called _sternbergiæ_ (fig. ). these sternbergia piths, however, occur in true conifers as well, as they do in the modern world in some trees, like our common butternut, of higher type; and i showed many years ago that the sternbergia type may be detected in the young twigs of the balsam-fir (_abies balsamifera_). the pith was surrounded by a ring of scalariform or barred tissue, often of considerable thickness, and in young stems so important as to have suggested lycopodiaceous affinities. but as the stem grew in size, a regular ring of woody wedges, with tissue having rounded or hexagonal pores or discs, like those of pines, was developed. outside this was a bark, often apparently of some thickness. this structure in many important points resembles that of cycads, and also approaches to the structure of sigillaria, while in its more highly developed forms it approximates to that of the conifers. [illustration: fig. .--_cordaites_ (_dorycordaites_), grand d'eury, reduced.] [illustration: fig. .--fruits of _cordaites_ and taxine conifers (coal-formation. nova scotia.) a, _antholithes squamosus_ (two thirds). b, _a. rhabdocarpi_. (two thirds). b^ , carpel restored. c, _a. spinosus_ (natural size). d, _trigonocarpum intermedium_. e, _t. noeggerathii_. f, _t. avellanum_. g, _rhabdocarpus insignis_, reduced. h, _antholithes pygmæus_. i, _cardiocarpum fluitans_. k, _cardiocarpum bisectum_. l, _sporangites papillata_, lycopodiaceous macrospores (natural size and magnified).] on the stems so constructed were placed long and often broad many-nerved leaves, with rows of stomata or breathing-pores, and attached by somewhat broad bases to the stem and branches. the fruit consisted of racemes, or clusters of nutlets, which seem to have been provided with broad lateral wings for flotation in the air, or in some cases with a pulpy envelope, which flattens into a film. there seem to have been structures of both these kinds, though in the state of preservation of these curious seeds it is extremely difficult to distinguish them. in the first case they must have been intended for dissemination by the wind, like the seeds of spruces. in the latter case they may have been disseminated like the fruits of taxine trees by the agency of animals, though what these were it would be difficult to guess. these trees had very great reproductive power, since they produced numerous seeds, not singly or a few together, as in modern yews, but in long spikes or catkins bearing many seeds (fig. ). it is to be observed that the cordaites, or the _cordaitinæ_, as they have been called, as a family,[cf] constitute another of those intermediate groups with which we have already become familiar. on the one hand they approach closely to the broader-leaved yews like gingko, phyllocladus, and podocarpus, and, on the other hand, they have affinities with cycadaceæ, and even with sigillariæ. they were beautiful and symmetrical trees, adding something to the variety of the rather monotonous palæozoic forests. they contributed also somewhat to the accumulation of coal. i have found that some thin beds are almost entirely composed of their leaves, and the tissues of their wood are not infrequent in the mineral charcoal of the larger coal-seams. there is no evidence that their roots were of the stigmaroid type, though they evidently grew in the same swampy flats with the sigillariæ and calamites. [cf] engler; cordaitées of renault. it may, perhaps, be well to say here that i believe there was a considerably wide range of organisation in the cordaitinæ as well as in the calamites and sigillariæ, and that it will eventually be found that there were three lines of connection between the higher cryptogams and the phænogams, one leading from the lycopods by the sigillariæ, another leading by the cordaites, and the third leading from the equisetums by the calamites. still further back the characters afterward separated in the club-mosses, mare's-tails, and ferns, were united in the rhizocarps, or, as some now, but i think somewhat unreasonably, prefer to call them, the "heterosporous filicinæ." in the more modern world, all the connecting links have become extinct and the phænogams stand widely separated from the higher cryptogams. i do not make these remarks in a darwinian sense, but merely to state what appear to be the lines of natural affinity and the links wanting to give unity to the system of nature. of all the trees of the modern world, none are perhaps so widely distributed as the pines and their allies. on mountain-tops and within the arctic zone, the last trees that can struggle against the unfavourable conditions of existence are the spruces and firs, and in the warm and moist islands of the tropics they seem equally at home with the tree-ferns and the palms. we have already seen that they are a very ancient family, and in the sandstones of the coal-formation their great trunks are frequently found, infiltrated with calcareous or silicious matter, and still retaining their structure in the greatest perfection (fig. ). so far as we know, the foliage of some of them which constitutes the genera _walchia_ and _araucarites_ of some authors (figs. , ) was not dissimilar from that of modern yews and spruces, though there is reason to believe that some others had broad, fern-like leaves like those of the gingko. none of them, so far as yet certainly known, were cone-bearing trees, their fruit having probably been similar to that of the yews (fig. ). the minute structures of their stems are nearer to those of the conifers of the islands of the southern hemisphere than to that of those in our northern climes--a correlation, no doubt, to the equable climate of the period. there is not much evidence that they grew with the sigillariæ in the true coal-swamps, though some specimens have been found in this association. it is more likely that they were in the main inland and upland trees, and that in consequence they are mostly known to us by drifted trunks borne by river inundations into the seas and estuaries. [illustration: fig. .--coniferous wood and foliage (carboniferous). a, _araucarites gracilis_, reduced, b, _dadoxylon acadianum_ (radial), diams.; b^ (tangential), diams; b^ , cell showing areolation, diams. c, _dadoxylon materiarium_ (radial), diams.; c^ (tangential), diams. c^ , cell showing areolation, diams. d, _dadoxylon antiquius_ (radial), diams.; d^ (tangential), diams.; d^ , cell showing areolation, diams.] [illustration: fig. .--__trigonocarpum hookeri_, dawson from the coal-measures of cape breton. probably the fruit of a taxine tree. a, broken specimen magnified twice natural size, b, section magnified: _a_, the testa; _b_, the tegmen; _c_, the nucleus; _d_, the embryo, _c_, portion of the surface of the inner coat more highly magnified.] a remarkable fact in connection with them, and showing also the manner in which the most durable vegetable structures may perish by decay, is that, like the cordaites, they had large piths with transverse partitions, a structure which, as i have already mentioned, appears on a minute scale in the twigs of the fir-tree, and that sometimes casts of these piths in sandstone appear in a separate form, constituting what have been named _sternbergiæ_ or _artisiæ_. as renault well remarks with reference to cordaites, the existence of this chambered form of pith implies rapid elongation of the stem, so that the cordaites and conifers of the coal-formation were probably quickly growing trees (fig. ). [illustration: fig. .--_sternbergia_ pith of _dadoxylon_. a, specimen (natural size), showing remains of wood at _a_, _a_. b, junction of wood and pith, magnified. c, cells of the wood of do., _a_, _a_; _b_, medullary ray; _c_, areolation.] the same general statements may be made as to the coal-vegetation as in relation to that of the erian. in the coal period we have found none of the higher exogens, and there are only obscure and uncertain indications of the presence of endogens, which we may reserve for a future chapter; but gymnosperms abound and are highly characteristic. on the other hand, we have no mosses or lichens, and very few algæ, but a great number of ferns and lycopodiaceæ or club-mosses (fig. ). thus, the coal-formation period is botanically a meeting-place of the lower phænogams and the higher cryptogams, and presents many forms which, when imperfectly known, have puzzled botanists in regard to their position in one or other series. in the present world, the flora most akin to that of the coal period is that of warm, temperate regions in the southern hemisphere. it is not properly a tropical flora, nor is it the flora of a cold region, but rather indicative of a moist and equable climate. still, we must bear in mind that we may often be mistaken in reasoning as to the temperature required by extinct species of plants, differing from those now in existence. further, we must not assume that the climatal conditions of the northern hemisphere were in the coal period at all similar to those which now prevail. as sir charles lyell has shown, a less amount of land in the higher latitudes would greatly modify climates, and there is every reason to believe that in the coal period there was less land than now. further, it has been shown by tyndall that a very small additional amount of carbonic acid in the atmosphere would, by obstructing the radiation of heat from the earth, produce almost the effect of a glass roof or conservatory, extending over the whole world. again, there is much in the structure of the leaves of the coal-plants, as well as in the vast amount of carbon which they accumulated in the form of coal, and the characteristics of the animal life of the period, to indicate, on independent grounds, that the carboniferous atmosphere differed from that of the present world in this way, or in the presence of more carbonic acid--a substance now existing in the very minute proportion of one thousandth of the whole--a quantity adapted to the present requirements of vegetable and animal life, but probably not to those of the coal period. [illustration: fig. .--_walchia imbricatula_, s. n., permian, prince edward island.] thus, if we inquire as to any analogous distribution of plants in the modern world, we find this only in the warmer insular climates of the southern hemisphere, where ferns, lycopods, and pines appear under forms somewhat akin to those of the carboniferous, but mixed with other types, some of which are modern, others allied to those of the next succeeding geological ages of the mesozoic and tertiary; and under these periods it will be more convenient to make comparisons. the readers of recent english popular works on geology will have observed the statement reiterated that a large proportion of the material of the great beds of bituminous coal is composed of the spore-cases of lycopodiaceous plants--a statement quite contrary to that resulting from my microscopical examinations of the coal of more than eighty coal-beds in nova scotia and cape breton, as stated in "acadian geology" (page ), and more fully in my memoir of on the "structures in coal,"[cg] and that of , on the "conditions of accumulation of coal."[ch] the reason of this mistake is, that an eminent english naturalist, happening to find in certain specimens of english coal a great quantity of remains of spores and spore-cases, though even in his specimens they constitute only a small portion of the mass, and being apparently unacquainted with what others had done in this field, wrote a popular article for the "contemporary review," in which he extended an isolated and exceptional fact to all coals, and placed this supposed origin of coal in a light so brilliant and attractive that he has been followed by many recent writers. the fact is, as stated in "acadian geology," that trunks of _sigillariæ_ and similar trees constitute a great part of the denser portion of the coal, and that the cortical tissues of these rather than the wood remain as coal. but cortical or epidermal tissues in general, whether those of spore-cases or other parts of plants, are those which from their resistance to water-soakage and to decay, and from their highly carbonaceous character, are best suited to the production of coal. in point of fact, spore-cases, though often abundantly present, constitute only an infinitesimal part of the matter of the great coal-beds. in an article in "the american journal of science," which appeared shortly after that above referred to, i endeavoured to correct this error, though apparently without effect in so far as the majority of british geological writers are concerned. from this article i have taken with little change the following passages, as it is of importance in theoretical geology that such mistakes, involving as they do the whole theory of coal accumulation, should not continue to pass current. the early part of the paper is occupied with facts as to the occurrence of spores and spore-cases as partial ingredients in coal. its conclusions are as follows: it is not improbable that sporangites, or bodies resembling them, may be found in most coals; but it is most likely that their occurrence is accidental rather than essential to coal accumulation, and that they are more likely to have been abundant in shales and cannel coals, deposited in ponds or in shallow waters in the vicinity of lycopodiaceous forests, than in the swampy or peaty deposits which constitute the ordinary coals. it is to be observed, however, that the conspicuous appearance which these bodies, and also the strips and fragments of epidermal tissue, which resemble them in texture, present in slices of coal, may incline an observer, not having large experience in the examination of coals, to overrate their importance; and this i think has been done by most microscopists, especially those who have confined their attention to slices prepared by the lapidary. one must also bear in mind the danger arising from mistaking concretionary accumulations of bituminous matter for sporangia. in sections of the bituminous shales accompanying the devonian coal above mentioned, there are many rounded yellow spots, which on examination prove to be the spaces in the epidermis of _psilophyton_ through which the vessels passing to the leaves were emitted. to these considerations i would add the following, condensed from the paper above referred to (p. ), in which the whole question of the origin of coal is fully discussed:[ci] [cg] "journal of the geological society," vol. xv. [ch] _ibid._, vol. xxii. [ci] see also "acadian geology," d ed., pp. , , . . the mineral charcoal or 'mother coal' is obviously woody tissue and fibres of bark, the structure of the varieties of which, and the plants to which it probably belongs, i have discussed in the paper above mentioned. . the coarser layers of coal show under the microscope a confused mass of fragments of vegetable matter belonging to various descriptions of plants, and including, but not usually in large quantities, sporangites. . the more brilliant layers of the coal are seen, when separated by thin laminæ of clay, to have on their surfaces the markings of _sigillariæ_ and other trees, of which they evidently represent flattened specimens, or rather the bark of such specimens. under the microscope, when their structures are preserved, these layers show cortical tissues more abundantly than any others. . some thin layers of coal consist mainly of flattened layers of leaves of _cordaites_ or _pychnophyllum_. . the _stigmaria_ under-clays and the stumps of _sigillaria_ in the coal-roofs equally testify to the accumulation of coal by the growth of successive forests, more especially of _sigillariæ_. there is, on the other hand, no necessary connection of sporangite-beds with stigmarian soils. such beds are more likely to be accumulated in water, and consequently to constitute bituminous shales and cannels. . _lepidodendron_ and its allies, to which the spore-cases in question appear to belong, are evidently much less important to coal accumulation than _sigillaria_, which cannot be affirmed to have produced spore-cases similar to those in question, even though the observation of goldenberg as to their fruit can be relied on; the accuracy of which, however, i am inclined to doubt. on the whole, then, while giving due credit to those who have advocated the spore-theory of coal, for directing attention to this curious and no doubt important constituent of mineral fuel, and admitting that i may possibly have given too little attention to it, i must maintain that sporangite-beds are exceptional among coals, and that cortical and woody matters are the most abundant ingredients in all the ordinary kinds; and to this i cannot think that the coals of england constitute an exception. it is to be observed, in conclusion, that the spore-cases of plants, in their indestructibility and richly carbonaceous character, only partake of qualities common to most suberous and epidermal matters, as i have explained in the publications already referred to. such epidermal and cortical substances are extremely rich in carbon and hydrogen, in this resembling bituminous coal. they are also very little liable to decay, and they resist more than other vegetable matters aqueous infiltration--properties which have caused them to remain unchanged, and to continue free from mineral additions more than other vegetable tissues. these qualities are well seen in the bark of our american white birch. it is no wonder that materials of this kind should constitute considerable portions of such vegetable accumulations as the beds of coal, and that when present in large proportion they should afford richly bituminous beds. all this agrees with the fact, apparent on examination of the common coal, that the greater number of its purest layers consist of the flattened bark of _sigillariæ_ and similar trees, just as any single flattened trunk embedded in shale becomes a layer of pure coal. it also agrees with the fact that other layers of coal, and also the cannels and earthy bitumens, appear under the microscope to consist of finely comminuted particles, principally of epidermal tissues, not only from the fruits and spore-cases of plants, but also from their leaves and stems. these considerations impress us, just as much as the abundance of spore-cases, with the immense amount of the vegetable matter which has perished during the accumulation of coal, in comparison with that which has been preserved. i am indebted to dr. t. sterry hunt for the following very valuable information, which at once places in a clear and precise light the chemical relations of epidermal tissue and spores with coal. dr. hunt says: "the outer bark of the cork-tree, and the cuticle of many if not all other plants, consists of a highly carbonaceous matter, to which the name of _suberin_ has been given. the spores of _lycopodium_ also approach to this substance in composition, as will be seen by the following, one of two analyses by duconi,[cj] along with which i give the theoretical composition of pure cellulose or woody fibre, according to payen and mitscherlich, and an analysis of the suberin of cork, from _quercus suber_, from which the ash and · per cent of cellulose have been deducted.[ck] [cj] liebig and kopp, "jahresbuch," -' . [ck] gmelin, "handbook," xv., . ---------+-----------+--------+------------ | cellulose.| cork. | lycopodium. ---------+-----------+--------+------------ carbon | · | · | · hydrogen | · | · | · nitrogen | .... | · | · oxygen | · | · | · +-----------+--------+------------ total | · | · | · ---------+-----------+--------+------------ "this difference is not less striking when we reduce the above centesimal analyses to correspond with the formula of cellulose, c{ }h{ }o{ }, and represent cork and _lycopodium_ as containing twenty-four equivalents of carbon. for comparison i give the composition of specimens of peat, brown coal, lignite, and bituminous coal:[cl] [cl] "canadian naturalist," vi., . cellulose c{ }h{ }o{ } cork c{ }h{ - / }o{ - / } lycopodium c{ }h{ - / }no{ - / } peat (vaux) c{ }h{ - / }o{ } brown coal (schröther) c{ }h{ - / }o{ - / } lignite (vaux) c{ }h{ - / }o{ - / } bituminous coal (regnault) c{ }h{ }o{ - / } "it will be seen from this comparison that, in ultimate composition, cork and _lycopodium_ are nearer to lignite than to woody fibre, and may be converted into coal with far less loss of carbon and hydrogen than the latter. they in fact approach closer in composition to resins and fats than to wood, and, moreover, like those substances repel water, with which they are not easily moistened, and thus are able to resist those atmospheric influences which effect the decay of woody tissue." i would add to this only one further consideration. the nitrogen present in the _lycopodium_ spores, no doubt, belongs to the protoplasm contained in them, a substance which would soon perish by decay; and subtracting this, the cell-walls of the spores and the walls of the spore-cases would be most suitable material for the production of bituminous coal. but this suitableness they share with the epidermal tissue of the scales of strobiles, and of the stems and leaves of ferns and lycopods, and, above all, with the thick, corky envelope of the stems of _sigillariæ_ and similar trees, which, as i have elsewhere shown,[cm] from its condition in the prostrate and erect trunks contained in the beds associated with coal, must have been highly carbonaceous and extremely enduring and impermeable to water. in short, if, instead of "spore-cases," we read "epidermal tissues in general, including spore-cases," all that has been affirmed regarding the latter will be strictly and literally true, and in accordance with the chemical composition, microscopical characters, and mode of occurrence of coal. it will also be in accordance with the following statement, from my paper on the "structures in coal," published in : [cm] "vegetable structures in coal," "journal of geological society," xv., . "conditions of accumulation of coal," _ibid._, xxii., . "acadian geology," , . "a single trunk of _sigillaria_ in an erect forest presents an epitome of a coal-seam. its roots represent the _stigmaria_ under-clay; its bark the compact coal; its woody axis the mineral charcoal; its fallen leaves (and fruits), with remains of herbaceous plants growing in its shade, mixed with a little earthy matter, the layers of coarse coal. the condition of the durable outer bark of erect trees concurs with the chemical theory of coal, in showing the especial suitableness of this kind of tissue for the production of the purer compact coals. it is also probable that the comparative impermeability of the bark to mineral infiltration is of importance in this respect, enabling this material to remain unaffected by causes which have filled those layers, consisting of herbaceous materials and decayed wood, with pyrites and other mineral substances." we need not go far in search of the uses of the coal vegetation, when .we consider the fact that the greatest civilised nations are dependent on it for their fuel. without the coal of the carboniferous period and the iron-ore which is one of the secondary consequences of coal accumulation, just as bog-ores of iron occur in the subsoils of modern peats, it would have been impossible either to sustain great nations in comfort in the colder climates of the northern hemisphere or to carry on our arts and manufactures. the coal-formation yields to great britain alone about one hundred and sixty million tons of coal annually, and the miners of the united states extract mainly from the same formation nearly a hundred million tons, while the british colonies and dependencies produce about five million tons; and it is a remarkable fact that it is to the english race that the greatest supply of this buried power and heat and light has been given. the great forests of the coal period, while purifying the atmosphere of its excess of unwholesome carbonic acid, were storing up the light and heat of palæozoic summers in a form in which they could be recovered in our human age, so that, independently of their uses to the animals which were their contemporaries, they are indispensable to the existence of civilised man. nor can we hope soon to be able to dispense with the services of this accumulated store of fuel. the forests of to-day are altogether insufficient for the supply of our wants, and though we are beginning to apply water-power to the production of electricity, and though some promising plans have been devised for the utilisation of the direct heat and light of the sun, we are still quite as dependent as any of our predecessors on what has been done for us in the palæozoic age. in the previous pages i have said little respecting the physical geography of the carboniferous age; but, as may be inferred from the vegetation, this in the northern hemisphere presented a greater expanse of swampy flats little elevated above the sea than we find in any other period. as to the southern hemisphere, less is known, but the conditions of vegetation would seem to have been essentially the same. taking the southern hemisphere as a whole, i have not seen any evidence of a lower devonian or upper silurian flora; but in south africa and australia there are remains of upper devonian or lower carboniferous plants. these were succeeded by a remarkable upper carboniferous or permian group, which spread itself all over india, australia, and south africa,[cn] and contains some forms (_vertebraria_, _phyllotheca_, _glossopteris_, &c. ) not found in rocks of similar age in the northern hemisphere, so that, if the age of these beds has been correctly determined, the southern hemisphere was in advance in relation to some genera of plants. this, however, is to be expected when we consider that the triassic and jurassic flora of the north contains or consists of intruders from more southern sites. these beds are succeeded in india by others holding cycads, &c., of upper jurassic or lower cretaceous types (rajmahal and jabalpur groups). [cn] wyley, "journal geol. society," vol. xxiii., p. ; daintree, _ibid._, vol. xxviii.; also clarke and mccoy. blanford has shown that there is a very great similarity in this series all over the australian and indian region.[co] hartt and darby have in like manner distinguished devonian and carboniferous forms in brazil akin to those of the northern hemisphere. thus the southern hemisphere would seem to have kept pace with the northern, and according to blanford there is evidence there of cold conditions in the permian, separating the palæozoic flora from that of the mesozoic, in the same manner that ramsay has supposed a similar period of cold to have done north of the equator. this would imply a very great change of climate, since we have evidence of the extension of the lower carboniferous flora at least as far north as spitzbergen. the upper coal-formation we cannot, however, trace nearly so far north; so that a gradual refrigeration may have been going on before the permian. thus in both hemispheres there was a general similarity in the later palæozoic flora, and perhaps similar conditions leading to its extinction and to its replacement by that to be described in the next chapter. [co] "journal geol. society," vol. xxxi. * * * * * notes to chapter iv. i. characters and classification of palæozoic plants. in the space available in this work it would be impossible to enter fully into the classification of palæozoic plants; but it may be well to notice some important points for the guidance of those who may desire to collect specimens; more especially as much uncertainty exists as to affinities and very contradictory statements are made. the statements below may be regarded as the results of actual observation and of the study of specimens _in situ_ in the rocks, as well as in the cabinet and under the microscope. gymnospermeæ. _family_ coniferæ; _genus_ dadoxylon, endlicher; araucarites, goeppert; araucarioxylon, kraus. the trunks of this genus occur from the middle devonian to the permian inclusive, as drift-logs calcified, silicified, or pyritised. the only foliage associated with them is of the type of _walchia_ and _araucarites_--viz., slender branches with numerous small spiral acicular leaves. two of the coal-formation species, _d. materiarum_ and another, had foliage of this type. that of the others is unknown. they are all distinct from the wood of _cordaites_, for which see under that genus. the following are north american species: _trunks._ _dadoxylon ouangondianum_, dn. m. erian report, .[cp] _d. halli_, dn. " " _d. newberryi_, dn. " " _d. clarkii_, dn. (cordæoxylon ?) " report, . _d. acadianum_, dn. coal-formation acadian geology. and millstone grit. _d. materiarum_, dn. do. and permo- " carb. _d._ (_palæoxylon_) _antiquius_, dn. l. carboniferous. " _d. annulatum_, dn. coal-formation. " _ormoxylon erianum_, dn. erian report, . _foliage._ _araucarites gracilis_, dn. n. coal-formation " and permian. { report on _walchia robusta_, dn. permian. { prince edward _w. imbricatula_, dn. " { island. [cp] "geological survey of canada: fossil plants of erian and upper silurian formations," by j. w. dawson. all of the above can be vouched for as good species based upon microscopic examination of a very large number of trunks from different parts of north america. the three erian species of _dadoxylon_ and _d. antiquius_ from the lower carboniferous have two or more rows of cells in the medullary rays. the last named has several rows, and is a true _palæoxylon_ allied to _d. withami_ of great britain. _d. materiarium_ is specially characteristic of the upper coal-formation and permian, and to it must belong one or both of the species of foliage indicated above. _d. clarkii_ has very short, simple medullary rays of only a few cells superimposed, and has an inner cylinder of scalariform vessels, approaching in these points to _cordaites_. _ormoxylon_ has a very peculiar articulated pith and simple medullary rays. witham in described several carboniferous species of pine-wood, under the generic name pinites, separating under the name _pitus_ species which appeared to have the discs on the cell-walls separate and in transverse lines. witham's name was changed by goeppert to _araucarites_, to indicate the similarity of these woods to araucaria, _pinites_ being reserved for trees more closely allied to the ordinary pines. endlicher, restricting araucarites to foliage, etc., of araucaria-like trees, gave the name _dadoxylon_ to the wood; and this, through unger's "genera and species," has gained somewhat general acceptance. endlicher also gave the name _pissadendron_ to the species which witham had called _pitus_; but brongniart proposed the name _palæoxylon_ to include all the species with thick and complex medullary rays, whatever the arrangement of the discs. in schimper's new work kraus substitutes _araucarioxylon_ for endlicher's _dadoxylon_, and includes under _pissadendron_ all the species placed by brongniart in _palæoxylon_. to understand all this confusion, it may be observed that the characters available in the determination of palæozoic coniferous wood are chiefly the form and arrangement of the wood-cells, the character of the bordered pores or discs of their walls, and the form and composition of the medullary rays. the character on which witham separated his genus _pitus_ from _pinites_ is, as i have ascertained by examination of slices of one of his original specimens kindly presented to me by mr. sanderson, of edinburgh, dependent on state of preservation, the imperfectly preserved discs or areolations of the walls of the fibre presenting the appearance of separate and distinct circles, while in other parts of the same specimens these discs are seen to be contiguous and to assume hexagonal forms, so that in this respect they do not really differ from the ordinary species of _dadoxylon_. the true character for subdividing those species which are especially characteristic of the carboniferous, is the composite structure of the medullary rays, which are thick and composed of several radial piles of cells placed side by side. this was the character employed by brongniart in separating the genus _palæoxylon_, though he might with convenience have retained witham's name, merely transferring to the genus the species of witham's _pinites_ which have complex medullary rays. the erian rocks present the greatest variety of types, and _palæoxylon_ is especially characteristic of the lower carboniferous, while species of _dadoxylon_ with two rows of bordered pores and simple medullary rays are especially plentiful in the upper coal-formation and permo-carboniferous. the following table will clearly show the distinctive characters and relations of the genera in question, as held by the several authors above referred to: _wood of palæozoic conifers._ woody | medullary rays | generic | geological fibres. | and pith. | names. | age. -------------+--------------------+---------------------+--------------- no discs. | one or two series | _aporoxylon_, | devonian | of cells. | unger. | (erian). -------------+--------------------+---------------------+--------------- | complex, or of two | { _pitus_, | | or more series of | { witham. | middle and | or more series of | { _palæoxylon_, | lower | cells. | { brongniart. | carboniferous | pith sternbergian. | { _pissadendron_, | and devonian. | | { endlicher. | +--------------------+---------------------+--------------- discs in one | simple, or of one | { _araucarites_, | series | row of cells. | { goeppert | upper contiguous, | pith sternbergian. | { _dadoxylon_, | carboniferous or in | | { endlicher. | and permian. several | | { _araucarioxylon_, | series | | { schimper. | spirally +--------------------+---------------------+--------------- arranged. | pith in spherical | _ormoxylon_,[cq] dn. | devonian. | chambers. | | +--------------------+---------------------+--------------- | medullary sheath | | devonian. | scalariform. | _dadoxylon_ | | medullary rays | (cordæoxylon),[cr] | | frequent, simple, | dn. | | short. | | -------------+--------------------+---------------------+--------------- [cq] type _o. erianum_, dn., "report on canadian plants," . [cr] type _d. clarkii_, dn., "report on canadian plants," . this may be wood of cordaites, to which it approaches very closely. _family_ cordaites, _genus_ cordaites, brongniart. trunks marked by transverse scars of attachment of bases of leaves; leaves broad, with many parallel veins, and attached by a broad base; pistillate and staminate catkins of the nature of antholithes. fruit winged or pulpy, of the kind known as _cardiocarpum_. stem with a sternbergia pith, usually large, surrounded by a ring of pseudo-scalariform vessels, and with a cylinder usually narrow, of woody wedges, with bordered pores in one or more series, and with simple medullary rays. from specimens kindly presented to me by prof. renault, i have been able to ascertain that the stems of some at least of these plants (eucordaites) are distinct in structure from all the species of _dadoxylon_, above mentioned, except _d. clarkii_, of the erian. they may be regarded as intermediate between those of conifers and cycads, which is indeed the probable position of these remarkable plants. grand d'eury has divided the _cordaites_ into sub-genera, as follows: . _eucordaites._--leaves spatulate, obovate, elliptical, or lanceolate, sessile, entire, with rounded apices and of leathery consistency. the leaves are from twenty to ninety centimetres in length. the nerves are either equally or unequally strong. . _dorycordaites._--leaves lanceolate, with sharp points; nerves numerous, fine, and equal in strength. the leaves attain a length of from forty to fifty centimetres. . _poacordaites._--leaves narrow, linear, entire, blunt at the point, with nerves nearly equally strong. the leaves are as much as forty centimetres in length. to these renault and zeiller have added a fourth group, _scutocordaites_. _genus_ sternbergia. this is merely a provisional genus intended to receive casts of the pith cylinders of various fossil trees. their special peculiarity is that, as in the modern _cecropia peltata_, and some species of _ficus_, the pith consists of transverse dense partitions which, on the elongation of the internodes, become separated from each other, so as to produce a chambered pith cavity, the cast of which shows transverse furrows. the young twigs of the modern _abies balsamifera_ present a similar structure on a minute scale. i have ascertained and described such pith-cylinders in large stems of _dadoxylon ouangondianum_, and _d. materiarium_. they occur also in the stems of _cordaites_ and probably of _sigillariæ_. i have discussed these curious fossils at length in "acadian geology" and in the "journal of the geological society of london," . the following summary is from the last-mentioned paper: _a._ as prof. williamson and the writer have shown, many of the _sternbergia_ piths belong to coniferous trees of the genus _dadoxylon_. _b._ a few specimens present multiporous tissue, of the type of _dictyoxylon_, a plant of unknown affinities, and which, according to williamson, has a _sternbergia_ pith. _c._ other examples show a true scalariform tissue, comparable with that of _lepidodendron_ or _sigillaria_, but of finer texture. corda has shown that plants of the type of the former genus (his _lomatophloios_) had _sternbergia_ piths. some plants of this group are by external characters loosely reckoned by botanists as ribless _sigillariæ_ (_clathraria_); but i believe that they are not related even ordinally to that genus. _d._ many carboniferous _sternbergiæ_ show structures identical with those described above as occurring in _cordaites_, and also in some of the trees ordinarily reckoned as _sigillariæ_. _genus_ cardiocarpum. i have found at least eight species of these fruits in the erian and carboniferous of new brunswick and nova scotia, all of which are evidently fruits of gymnospermous trees. they agree in having a dense coaly nucleus of appreciable thickness, even in the flattened specimens, and surrounded by a thin and veinless wing or margin. they have thus precisely the appearance of samaras of many existing forest-trees, some of which they also resemble in the outline of the margin, except that the wings of samaras are usually veiny. the character of the nucleus, and the occasional appearance in it of marks possibly representing cotyledons or embryos, forbids the supposition that they are spore-cases. they must have been fruits of phænogams. whether they were winged fruits or seeds, or fruits with a pulpy envelope like those of cycads and some conifers, may be considered less certain. the not infrequent distortion of the margin is an argument in favour of the latter view, though this may also be supposed to have occurred in samaras partially decayed. on the other hand, their being always apparently flattened in one plane, and the nucleus being seldom, if ever, found denuded of its margin, are arguments in favour of their having been winged nutlets or seeds. until recently i had regarded the latter view as more probable, and so stated the matter in the second edition of "acadian geology." i have, however, lately arrived at the conclusion that the _cardiocarpa_ of the type of _c. cornutum_ were gymnospermous seeds, having two cotyledons embedded in an albumen and covered with a strong membranous or woody tegmen surrounded by a fleshy outer coat, and that the notch at the apex represents the foramen or micropyle of the ovule. the structure was indeed very similar to that of the seeds of _taxus_ and of _salisburia_. with respect to some of the other species, however, especially those with very broad margins, it still appears likely that they were winged. the _cardiocarpa_ were borne in racemes or groups, and it seems certain that some of them at least are the seeds of _cordaites_. the association of some of them and of those of the next genus with _sigillariæ_ is so constant that i cannot doubt that some of them belong to plants of that genus, or possibly to taxine conifers. the great number of distinct species of these seeds, as compared with that of known trees which could have produced them, is very remarkable. _genus_ trigonocarpum. these are large angled nuts contained in a thick envelope, and showing internal structures resembling those of the seeds of modern _taxineæ_. there are numerous species, as well as allied seeds referred to the provisional genera _rhabdocarpus_ and _carpolithes_. in _trigonocarpum hookeri_ i have described the internal structure of one of those seeds, and many fine examples from the coal-field of st. etienne, in france, have been described by brongniart, so that their internal structure is very well known. _genus_ antholithes. this is also a provisional genus, to include spikes of floral organs, some of which are known to have belonged to _cordaites_, others probably to _sigillariæ_. of uncertain affinities. _family_ sigillariaceæ. under this name palæobotanists have included a great number of trees of the carboniferous system, all of which are characterised by broad leaf-sears, with three vascular scars, and usually arranged in vertical rows, and by elongated three-nerved leaves, and roots of the stigmaria type--that is, with rounded pits, marking the attachment of rootlets spirally arranged. these trees, however, collected in the genus sigillaria by arbitrary characters, which pass into those of the lepidodendroid trees, have been involved in almost inextricable confusion, to disentangle which it will be necessary to consider: . the external characters of _sigillariæ_, and trees confounded with them. . subdivision of _sigillariæ_ by external markings. . the microscopic character of their stems. . what is known of their foliage and fruit. . _characters of sigillaroid and lepidodendroid trunks_. it may be premised that the modes of determination in fossil botany are necessarily different from those employed in recent botany. the palæobotanist must have recourse to characters derived from the leaves, the scars left by their fall, and the internal structures of the stem. these parts, held in little esteem by botanists in describing modern plants, and much neglected by them, must hold the first place in the regard of the fossil botanist, whereas the fructification, seldom preserved, and generally obscure, is of comparatively little service. it is to be remarked also that in such generalised plants as those of the palæozoic, remarkable rather for the development of the vegetative than of the reproductive organs, the former rise in importance as compared with their value in the study of modern plants. in _sigillariæ_, _lepidodendra_, &c., the following surfaces of the stem may be presented to our inspection: . the outer surface of the epidermis without its leaves, but with the leaf-bases and leaf-scars more or less perfectly preserved. on this surface we may recognise: ( ) cellular swellings or projections of the bark to which the leaves are attached. these may be called leaf-bases, and they are sometimes very prominent. ( ) the actual mark of the attachment of the leaf situated in the most prominent part of the leaf-base. this is the _leaf-scar_. ( ) in the leaf-scar when well preserved we can see one or more minute punctures or prominences which are the points where the vascular bundles passing to the leaf found exit. these are the vascular scars. when the leaves are attached, the leaf-scars and vascular scars cannot be seen, but the leaf-bases can be made out. hence it is important, if possible, to secure specimens with and without the leaves. in flattened specimens the leaf-bases are often distorted by pressure and marked with furrows which must not be mistaken for true structural characters. the leaf-bases, which are in relief on the outer surface of the stem, of course appear as depressions on the mould in the containing rock, in which the markings often appear much more distinctly than on the plant itself. . the outer surface of the epidermis may have been removed or may be destroyed by the coarseness of the containing rock. in this case the leaf-bases are usually preserved on the surface of the outer or corky bark, but the leaf-scars and vascular scars have disappeared. this gives that condition of lepidodendroid trees to which the name _knorria_ has been applied. when plants are in this state careful inspection may sometimes discover traces of the leaf-scars on portions of the stem, and thus enable the _knorria_ to be connected with the species to which it belongs. . the outer or corky bark may be removed, exposing the surface of the inner or fibrous and cellular bark, which in the plants in question is usually of great thickness. in this case neither the leaf-bases nor the scars are seen, but punctures or little furrows or ridges appear where the vascular bundles entered the inner bark. specimens in this state are usually said to be decorticated, though only the outer bark is removed. it is often difficult to determine plants in this condition, unless some portion of the stem can be found still retaining the bark; but when care is taken in collecting, it will not infrequently be found that the true outer surface can be recovered from the containing rock, especially if a coaly layer representing the outer bark intervenes between this and the inner impression. specimens of this kind, taken alone, have been referred to the genera _knorria_, _bothrodendron_, and _halonia_. . in some cases, though not frequently, the outer surface of the ligneous cylinder is preserved. it almost invariably presents a regularly striated or irregularly wrinkled appearance, depending upon the vertical woody wedges, or the positions of the medullary rays or vascular bundles. specimens of this kind constituted some of the _endogenites_ of the older botanists, and the genus _schizodendron_ of eichwald appears to include some of them. many of them have also been incorrectly referred to calamites. . in some cases the cast of the medullary cylinder or pith may alone be preserved. this may be nearly smooch or slightly marked by vertical striæ, but more usually presents a transverse striation, and not infrequently the transverse constrictions and septa characteristic of the genus sternbergia. loose _sternbergiæ_ afford little means of connecting them with the species to which they belong, except by the microscopic examination of the shreds of the ligneous cylinder which often cling to them.[cs] [cs] see my paper, "journal of geological society," vol. xxvii. these facts being premised, the following general statements may be made respecting some of the more common palæozoic genera, referring, however, principally to the perfect markings as seen on the epidermis: _sigillaria._--leaf-bases hexagonal or elongated, or confluent on a vertical ridge. leaf-scars hexagonal or shield-shaped. vascular scars three, the two lateral larger than the central. this last character is constant, depending on the fact that the leaves of sigillaria have two or more vascular bundles. all so-called _sigillariæ_ having the central vascular scar largest, or only one vascular bundle, should be rejected from this genus. in young branches of branching _sigillariæ_ the leaf-scars sometimes appear to be spiral, but in the older stems they form vertical rows; interrupted, however, by transverse rows or bands of _fruit-scars_, each with a single large central vascular scar, and which have borne the organs of fructification. _arthrocaulis_ of mccoy is founded on this peculiarity. _syringodendron._--differs from sigillaria in the leaf-scars, which are circular and with a single vascular bundle. it is a matter of doubt whether these plants were of higher rank than sigillaria tending toward the pines, or of lower rank tending toward cyclostigma. their leaf-bases form vertical ridges. _lepidodendron._--leaf-bases rhombic, oval, or lanceolate, moderately prominent. leaf-scars rhombic or sometimes shield-shaped or heart-shaped, in the middle or upper part of the leaf-base. vascular scars three--the middle one always largest and corresponding to the single nerve of the leaf; the lateral ones sometimes obsolete. in older stems three modes of growth are observed. in some species the expansion of the bark obliterates the leaf-bases and causes the leaf-scars to appear separated by wide spaces of more or less wrinkled bark, which at length becomes longitudinally furrowed and simulates the ribbed character of sigillaria. in others the leaf-bases grow in size as the trunk expands, so that even in large trunks they are contiguous though much larger than those on the branches. in others the outer bark, hardening at an early age, is incapable of either of the above changes, and merely becomes cleft into deep furrows in the old trunks. _lepidophloios._--leaf-bases transverse and prominent--often very much so. leaf-scars transversely rhombic or oval with three vascular scars, the central largest. leaves very long and one-nerved. large strobiles or branchlets borne in two ranks or spirally on the sides of the stem, and leaving large, round scars (_cone-scars_), often with radiating impressions of the basal row of scales. species with long or drooping leaf-bases have been included in _lepidophloios_ and _lomatophloios_, species with short leaf-bases and cone-scars in two rows have been called _ulodendron_, and some of them have been included in sigillaria (sub-genus _clathraria_). decorticated stems are bothrodendron and _halonia_. some of the species approach near to the last genus, especially to the lepidodendra with rhombic leaf-bases like _l. tetragonum_. _cyclostigma._--leaf-bases undeveloped. leaf-scars circular or horseshoe-shaped, small, with a central vascular scar. in old trunks of cyclostigma the leaf-scars become widely separated, and sometimes appear in vertical rows. young branches of lepidodendron sometimes have the leaf-scars similar to those of cyclostigma. _leptophleum._--leaf-bases flat, rhombic; leaf-scars obsolete; vascular scar single, central. the last two genera are characteristically devonian. in contradistinction from the trees above mentioned, the following general statements may be made respecting other groups: in conifers the leaf-bases are usually elongated vertically, often scaly in appearance, and with the leaf-scar terminal and round, oval, or rhombic, and with a single well-marked vascular scar. in calamites, calamodendron, and asterophyllites the scars of the branchlets or leaves are circular or oval, with only a single vascular scar, and situated in verticils at the top of well-marked nodes of the stem. in tree-ferns the leaf-bases are large and usually without a distinct articulating surface. the vascular bundles are numerous. protopteris has rounded leaf-scars with a large horseshoe-shaped bundle of vessels above and small bundles below. caulopteris has large elliptic or oval leaf-scars with vascular scars disposed concentrically. palæopteris,[ct] of geinitz, has the leaf-scars transversely oval and the vascular bundles confluent in a transverse band with an appendage or outlying bundle below. stemmatopteris has leaf-scars similar to those of caulopteris, but the vascular bundles united into a horseshoe-shaped band. [ct] this name, preoccupied by geinitz, has been inadvertently misapplied to the devonian ferns of the genus _archæopteris_. . _subdivision of sigillariæ in accordance with their markings_. the following groups may be defined in this way; but, being based on one character only, they are of course in all probability far from natural: . _sigillaria_, brongniart. type, _sigillaria reniformis_, brongniart, or _s. brounii_, dawson.--stem with broad ribs, usually much broader than the usually oval or elliptical tripunctate areoles, but disappearing at base, owing to expansion of the stem. leaves narrow, long, three-nerved. . _rhytidolepis_, sternberg. type, _s. scutellata_, brongniart.--ribs narrow, and often transversely striate. areoles large, hexagonal or shield-shaped, tripunctate. leaves as in last group. kings of rounded scars on the stems and branches mark attachment of fruit. it is possible that some of the smaller stems of this group may be branches of trees of group first. . _syringodendron_, sternberg. type, _s. organum_, l. and h., _s. oculata_, brongniart.--stems ribbed; areoles small and round, and apparently with a single scar, or three closely approximated. these are rare, and liable to be confounded with decorticated examples of other groups; but i have some specimens which unquestionably represent the external surface. . _favularia_, sternberg. type, _sigillaria elegans_ of brongniart.--leaf-bases hexagonal, or in young branches elliptical, in vertical rows, but without distinct ribs, except in old or decorticated stems. fruit borne in verticils on the branches bearing transverse rows of rounded scars. leaves somewhat broad and longitudinally striate. . _leioderma_, goldenberg. type, _s. sydnensis_, dawson.--ribs obsolete. cortical and ligneous surfaces striate. vascular scars double, elongate longitudinally, and alike on cortical and inner surfaces. areoles in rows and distinct; stigmaria-roots striate, with small and distinct areoles. . _clathraria_, brongniart. type, _s. menardi_, brongniart.--areoles hexagonal, not in distinct rows, but having a spiral appearance. some of the plants usually referred to this group are probably branches of _favularia_. others are evidently fragments of plants of the genus _lepidophloios_. . _internal structures of sigillaria-stems_. i long ago pointed out, on the evidence of the external markings and mode of growth, that the stems of _sigillariæ_ must have been exogenous, and this conclusion has now been fully confirmed by the microscopic researches of williamson, not only in the case of _sigillariæ_, but of _lepidodendra_ and _calamodendra_ as well. confining myself to my own observations, three types of _sigillariæ_ are known to me by their internal structures, though i cannot certainly correlate all of these with the external markings referred to above. . _diploxylon_, in which the stem consists of a small internal axis surrounded by a very thick inner bark and a dense outer cortex. a fine example from the south joggins is thus described:[cu] [cu] "journal of the geological society of london," november, . "the axis of the stem is about six centimetres in its greatest diameter, and consists of a central pith-cylinder and two concentric coats of scalariform tissue. the pith-cylinder is replaced by sandstone, and is about one centimetre in diameter. the inner cylinder of scalariform tissue is perfectly continuous, not radiated, and about one millimetre in thickness. its vessels are somewhat crushed, but have been of large diameter. its outer surface, which readily separates from that of the outer cylinder, is striated longitudinally. the outer cylinder, which constitutes by much the largest part of the whole, is also composed of scalariform tissue; but this is radially arranged, with the individual cells quadrangular in cross-section. the cross-bars are similar on all the sides and usually simple and straight, but sometimes branching or slightly reticulated. the wall intervening between the bars has extremely delicate longitudinal waving lines of ligneous lining, in the manner first described by williamson as occurring in the scalariform tissue of certain _lepidodendra_. a few small radiating spaces, partially occupied with pyrites, obscurely represent the medullary rays, which must have been very feebly developed. the radiating bundles passing to the leaves run nearly horizontally; but their structure is very imperfectly preserved. the stem being old and probably long deprived of its leaves, they may have been partially disorganised before it was fossilised. the outer surface of the axis is striated longitudinally, and in some places marked with impressions of tortuous fibres, apparently those of the inner bark. in the cross-section, where weathered, it shows concentric rings; but under the microscope these appear rather as bands of compressed tissue than as proper lines of growth. they are about twenty in number. this tree has an erect, ribbed trunk, twelve feet in height and fifteen inches in diameter, swelling to about two feet at the base." . _favularia type._--this has been well described by brongniart and by renault,[cv] and differs from the above chiefly in the fact that the outer exogenous woody zone is composed of reticulated instead of scalariform tissue, and the inner zone is of the peculiar form which i have characterised as pseudo-scalariform. [cv] "botanique fossile," paris, . . _sigillaria proper._--this i have illustrated in my paper in the "journal of the geological society" for may, , and it appears to represent the highest and most perfect type of the larger ribbed _sigillaria_. this structure i have described as follows, basing my description on a very fine axis found in an erect stem, and on the fragments of the woody axis found in the bases of other erect stems: _a._ a dense cellular outer bark, usually in the state of compact coal--but when its structure is preserved, showing a tissue of thickened parenchymatous cells. _b._ a very thick inner bark, which has usually in great part perished, or been converted into coal, but which, in old trunks, contained a large quantity of prosenchymatous tissue, very tough and of great durability. this "bast-tissue" is comparable with that of the inner bark of modern conifers, and constitutes much of the mineral charcoal of the coal-seams. _c._ an outer ligneous cylinder, composed of wood-cells, either with a single row of large bordered pores,[cw] in the manner of pines and cycads, or with two, three, or four rows of such pores sometimes inscribed in hexagonal areoles in the manner of dadoxylon. this woody cylinder is traversed by medullary rays, which are short, and composed of few rows of cells superimposed. it is also traversed by oblique radiating bundles of pseudo-scalariform tissue proceeding to the leaves. in some _sigillariæ_ this outer cylinder was itself in part composed of pseudo-scalariform tissue, as in brongniart's specimen of _s. elegans_; and in others its place may have been taken by multiporous tissue, as in a case above referred to; but i have no reason to believe that either of these variations occurred in the typical ribbed species now in question. the woody fibres of the outer cylinder may be distinguished most readily from those of conifers, as already mentioned, by the thinness of their walls, and the more irregular distribution of the pores. additional characters are furnished by the medullary rays and the radiating bundles of scalariform tissue when these can be observed. [cw] these are the same with the wood-cells elsewhere called discigerous tissue, and to which i have applied the terms uniporous and multiporous. the markings on the walls are caused by an unlined portion of the cell-wall placed in a disk or depression, and this often surrounded by an hexagonal rim of thickened wall; but in all cases these structures are less pronounced than in _dadoxylon_, and less regular in the walls of the same cell, as well as in different layers of the tissues of the axis. _d._ an inner cylinder of pseudo-scalariform tissue. i have adopted the term pseudo-scalariform for this tissue, from the conviction that it is not homologous with the scalariform ducts of ferns and other acrogens, but that it is merely a modification of the discigerous wood-cells, with pores elongated transversely, and sometimes separated by thickened bars, corresponding to the hexagonal areolation of the ordinary wood-cells. a similar tissue exists in cycads, and is a substitute for the spiral vessels existing in ordinary exogens. _e._ a large medulla, or pith, consisting of a hollow cylinder of cellular tissue, from which proceed numerous thin diaphragms towards the centre of the stem. these structures of the highest type of _sigillaria_ are on the one hand scarcely advanced beyond those of calamopitus, as described by williamson, and on the other approach to those of _cordaites_, as seen in specimens presented to me by renault. finally, as to the fruit of _sigillariæ_, i have no new facts to offer. the strobiles or spikes associated with these trees have been variously described as gymnospermous (renault) or cryptogamous (groldenberg and williamson). have never seen them in place. two considerations, however, have always weighed with me in reference to this subject. one is the constant abundance of trigonocarpa and cardiocarpa in the soil of the sigiliaria forests, as i have studied this at the south joggins. the other is that the rings of fruit-scars on the branches of sigiliaria are homologous with leaf-scars, not with branches, and therefore should have borne single carpels and not cones or spikes of inflorescence. these are merely suggestions, but i have no doubt they will be vindicated by future discoveries, which will, i have no doubt, show that in the family _sigillariaceæ_ we have really two families, one possibly of gymnospermous rank, or at least approaching to this, the other allied to the lepidodendra. cryptogamia. (_acrogenes._) _family_ lepidodendreæ; _genus_ lepidodendron, sternberg. these are arboreal lycopods having linear one-nerved leaves, stems branching dichotomously, and with ovate or rhombic leaf-bases bearing rhombic leaf-scars, often very prominent. the fruit is in scaly strobiles, terminal or lateral, and there are usually, if not always, macrospores and microspores in each strobile. the young branches and stems have a central pith, a cylinder of scalariform tubes sending out ascending bundles to the leaves through a thick cellular and fibrous inner bark, and externally a dense cortex confluent with or consisting of the leaf-bases. older stems have a second or outer layer of scalariform fibres in wedges with medullary rays, and strengthening the stem by a true exogenous growth, much as in the diploxylon type of sigiliaria. the development of this exogenous cylinder is different in amount and rate in different species.[cx] this different development of the exogenous axis is accompanied with appropriate external appearances in the stems, and the changes which take place in their markings. these are of three kinds. in some species the areoles, at first close together, become, in the process of the expansion of the stem, separated by intervening spaces of bark in a perfectly regular manner; so that in old stems, while widely separated, they still retain their arrangement, while in young stems they are quite close to one another. this is the case in _l. corrugatum_. in other species the leaf-scars or bases increase in size in the old stems, still retaining their forms and their contiguity to each other. this is the case in _l. undulatum_, and generally in those _lepidodendra_ which have large leaf-bases. in these species the continued vitality of the bark is shown by the occasional production of lateral strobiles on large branches, in the manner of the modern red pine of america. in other species the areoles neither increase in size nor become regularly separated by growth of the intervening bark; but in old stems the bark splits into deep furrows, between which may be seen portions of bark still retaining the areoles in their original dimensions and arrangement. this is the case with _l. pictoense_. this cracking of the bark no doubt occurs in very old trunks of the first two types, but not at all to the same extent. [cx] see "memoirs of dr. williamson," in "philosophical transactions," for ample details. as a type of lepidodendron, i may describe one of the oldest carboniferous species characteristic of the lower carboniferous in america, and corresponding to _l. veltheimianum_ of europe. lepidodendron corrugatum, dawson.--(see fig. , _supra_.) "quarterly journal of geological society," vol. xv.; "acadian geology," page . _habit of growth._--somewhat slender, with long branches and long, slender leaves having a tendency to become horizontal or drooping. _markings of stem._--leaf-bases disposed in quincunx or spirally, elongate, ovate, acute at both ends, but more acute and slightly oblique at the lower end; most prominent in the upper third, and with a slight vertical ridge. leaf-scars small, rounded, and showing only a single punctiform vascular scar. the leaf-scar on the outer surface is in the upper third of the base; but the obliquity of the vascular bundle causes it to be nearly central on the inside of the epidermis. in young succulent shoots the leaf-scars are contiguous and round as in cyclostigma, without distinct leaf-bases. in this state it closely resembles _l. olivieri_, eichwald.[cy] [cy] lethæa rossica, plate y, figs. , . in the ordinary young branches the leaf-scars are contiguous, and closely resemble those of _l. elegans_, brongt. (fig. c). as the branches increase in diameter the leaf-scars slightly enlarge and sometimes assume a verticillate appearance (fig. d). as they still further enlarge they become separated by gradually increasing spaces of bark, marked with many waving striæ or wrinkles (fig. i, n). at the base of old stems the bark assumes a generally wrinkled appearance without distinct scars. _knorria or decorticated states._--of these there is a great variety, depending on the state of preservation, and the particular longitudinal ridges. fig. d shows a form in which the vascular bundles appear as cylindrical truncate projections. other forms show the leaf-bases prominent, or have an appearance of longitudinal ribbing produced by the expansion of the bark. _structure of stem._--this is not perfectly preserved in any of my specimens, but one flattened specimen shows a central medulla with a narrow ring of scalariform vessels surrounding it, and constituting the woody axis. the structure is thus similar to that of _l. harcourtii_, which i regard as probably the same with the closely allied european species l. veltheimianum. _leaves._--these are narrow, one-nerved, curving somewhat rapidly outward (figs. , b, c, d). they vary from one to two inches in length. _roots._--i have not seen these actually attached, but they occur very abundantly in the under-clays of some erect forests of these plants at horton bluff, and are of the character of stigmariæ (figs. , ). in some of the under-clays the long, flattened rootlets are excessively abundant, and show the mark of a central vascular bundle. _fructification._--cones terminal, short, with many small, acute imbricate scales. spore-cases globular, smooth (fig. c). on the surface of some shales and sandstones at horton there are innumerable round spore-cases of this tree about the size of mustard-seed (fig. f). large slabs are sometimes covered with these, and thin layers of shale are filled with flattened specimens. this is the characteristic species of the lower carboniferous coal-measures, occurring in great profusion at horton bluff and its vicinity, also at sneid's mills near windsor, noel and five-mile river, at norton creek and elsewhere in new brunswick (matthew's collection), and at antigonish (honeyman's collection). i have received from the lowest carboniferous beds of ohio specimens of this species.[cz] according to rogers and lesquereux similar forms occur in the vespertine of pennsylvania and in the lower carboniferous of illinois. _l. veltheimianum_ of western europe and _l. glincanum_ of russia are closely allied lower carboniferous species.[da] [cz] "journal of geological society," november, , p. . [da] for comparisons of these see "report on plants of lower carboniferous of canada," p. . a very different type is furnished by a new species from the middle coal-formation of clifton, new brunswick. lepidodendron cliftonense, dawson.--habit of growth.--robust, with thick branches, and leaves several inches in length. terminal branches becoming slender, with shorter leaves. _markings of stem._--leaf-bases long oval, pointed at ends, enlarging with growth of stem. leaf-scars central, rhombic, transverse. _leaves._--one-nerved, acutely pointed, from four inches in length on the larger branches to one inch or less on the branchlets. _fructification._--cones large, cylindrical or long oval, with large scales of trigonal form, and not elongated but lying close to the surface. borne on lateral, slender branchlets, with short leaves. _genus_ lepidophloios, sternberg; ulodendron, l. and h.; lomatophloios, corda. _lepidophloios._--under this generic name, established by sternberg, i include those lycopodiaceous trees of the coal-measures which have thick branches, transversely elongated leaf-scars, each with three vascular points and placed on elevated or scale-like protuberances, long one-nerved leaves, and large lateral strobiles in vertical rows or spirally disposed. their structure resembles that of _lepidodendron_, consisting of a _sternbergia_ pith, a slender axis of large scalariform vessels, giving off from its surface bundles of smaller vessels to the leaves, a very thick cellular bark, and a thin dense outer bark, having some elongated cells or bast-tissue on its inner side. in these trees the exogenous outer cylinder is less developed than in the lepidodendra, and is sometimes wanting in stems or branches of some thickness. regarding _l. laricinum_ of sternberg as the type of the genus, and taking in connection with this the species described by goldenberg, and my own observations on numerous specimens found in nova scotia, have no doubt that _lomatophloios crassicaulis_ of corda, and other species of that genus described by goldenberg, _ulodendron_ and _bothrodendron_ of lindley, _lepidodendron ornatissimum_ of brongniart, and _halonia punctata_ of geinitz, all belong to this genus, and differ from each other only in conditions of growth and preservation. several of the species of _lepidostrobus_ and _lepidophyllum_ also belong to _lepidophloios_. the species of _lepidophloios_ are readily distinguished from _lepidodendron_ by the form of the areoles, and by the round scars on the stem, which usually mark the insertion of the large strobiles, though in barren stems they may also have produced branches; still, the fact of my finding the strobiles _in situ_ in one instance, the accurate resemblance which the scars bear to those left by the cones of the red pine when borne on thick branches, and the actual impressions of the radiating scales in some specimens, leave no doubt in my mind that they are usually the marks of cones; and the great size of the cones of _lepidophloios_ accords with this conclusion. the species of _lepidophloios_ are numerous, and individuals are quite abundant in the coal formation, especially toward its upper part. their flattened bark is frequent in the coal-beds and their roofs, affording a thin layer of pure coal, which sometimes shows the peculiar laminated or scaly character of the bark when other characters are almost entirely obliterated. the leaves also are nearly as abundant as those of sigillaria in the coal-shales. they can readily be distinguished by their strong, angular midrib. the markings of _lepidophloios_ may easily be mistaken for those of the _clathraria_ type of _sigillaria_. when the stem only is seen, they can be distinguished by the length of the leaf-bases in _lepidophloios_, and by the dominant central vascular scar; also by the one-nerved and ribbed leaves. where the large, round marks of the cones are present, these are an infallible guide, never being present in _sigillaria_. as the cones grew on the upper sides of the branches, the impression of the lower side often shows no cone-scars, or only two lateral rows, whereas on the upper side of the same branch they appear spirally arranged. i may describe as an example-- _lepidophloios acadianus_, dawson. leaf-bases broadly rhombic, or in old stems regularly rhombic, prominent, ascending, terminated by very broad rhombic scars having a central point and two lateral obscure points. outer bark laminated or scaly. surface of inner bark with single points or depressions. leaves long, linear, with a strong keel on one side, five inches or more in length. cone-scars sparsely scattered on thick branches, either in two rows or spirally, both modes being sometimes seen on the same branch. scalariform axis scarcely an inch in diameter in a stem five inches thick. fruit, an ovate strobile with numerous acute scales covering small globular spore-cases. this species is closely allied to _ulodendron majus_ and _lepidophloios laricinus_, and presents numerous varieties of marking. coal-formation, nova scotia. _family_ calamiteæ; _genus_ calamites, suckow. the plants of this genus are unquestionably allied to the modern _equisetaceæ_, but excel these so much in variety of form and structure, and are so capricious in their states of preservation, and so liable to be mistaken for parts of plants generically different, that they have given rise to much controversy. the following considerations will enable us to arrive at some certainty. the genus _calamites_ was originally founded in the longitudinally ribbed and jointed stems so frequent in the coal-formation, and of which the common _c. suckovii_ is a typical form. the most perfect of these stems represent the outer surface immediately within the epidermis, in which case transverse lines or constrictions mark the nodes, and at the nodes there are rounded spots, sometimes indicating radial processes of the pith, first described by williamson; in other cases, the attachment of branchlets, or in some specimens both. but some specimens show the outer surface of the epidermis, in which case the transverse nodal lines are usually invisible, though the scars of branchlets may appear. in still other examples the whole of the outer tissues have perished, and the so-called calamite is a cast of the interior of the stem, showing merely longitudinal ribbing and transverse nodal constrictions. in studying these plants _in situ_ in the erect calamite brakes of the coal-formation of nova scotia, one soon becomes familiar with these appearances, but they are evidently unknown to the majority of palæobotanists, though described in detail more than twenty years ago. when the outer surface is preserved it is sometimes seen to bear verticils of long needle-like leaves (_c. cistii_), or of branchlets with secondary whorls of similar leaves (_c. suckovii_ and _c. undulatus_). no calamite known to me bears broad one-nerved leaves like those of _asterophyllites_ and _annularia_, though the larger stems of these plants have been described as calamites, and the term _calamocladus_ has been used to include both groups. the base of the calamite stem usually terminates in a blunt point, and may be attached to a rhizome, or several stems may bud out from each other in a group or stool. the roots are long and cylindrical, sometimes branching. the fruit consists of spikes of spore-cases, borne in whorls and subtended by linear floral leaves. to these strobiles the name calamostachys has been given. williamson has shown that the stem of calamites consists of a central pith or cavity of large size surrounded by a cylinder consisting of alternate wedges of woody and cellular matter, with vertical canals at the inner sides of the wedges, and slender medullary rays. the thick cellular wedges intervening between the woody wedges he calls primary medullary rays; the smaller medullary rays in the wedges, secondary medullary rays. there is thus a highly complex exogenous stem based on the same principle with the stem of a common _equisetum_, but with much greater strength and complexity. williamson has also shown that there are different sub-types of these stems. more especially he refers to the three following: (_a_) _calamites_ proper, which has the woody wedges of scalariform or barred tissue with thin medullary rays, and the thick primary medullary rays are cellular. (_b_) _calamopitus_ has reticulated or multiporous tissue in the woody wedges with medullary rays, and the primary medullary wedges are composed of elongated cells. (_c_) _calamodendron_ has the woody wedges of barred tissue as in _a_, with medullary rays, but has the intervening medullary wedges of an elongated tissue approaching to woody fibre, and also with medullary rays. to these i would add a fourth type, which i have described, from the coal-formation of nova scotia.[db] [db] "quarterly journal of the geological society," . (_d_) _eucalamodendron_ differs from _calamodendron_ in having true bordered pores or pseudo-scalariform slit-pored tissue, and corresponds to the highest type of calamitean stem. i would also add that under _a_ and _b_ there are some species in which the woody cylinder is very thin in comparison to the size of the stem. in _c_ and _d_ the woody cylinder is thick and massive, and the stems are often large and nodose. as an example of an ordinary calamite in which the external surface and foliage are preserved, i may quote the following from my report on the "flora of the lower carboniferous and millstone grit," : calamites undulatus, brongniart.--this species is stated by brongniart to be distinguished from the _c. suckovii_, the characteristic calamite of the middle coal-formation, by its undulated ribs marked with peculiar cellular reticulation. he suggests that it may be merely a variety of _c. suckovii_, an opinion in which schimper coincides; but since i have received large additional collections from mr. elder, containing not only the stems and branches, but also the leaves and rhizomes, i am constrained to regard it as a distinct though closely allied species. the rhizomata are slender, being from one to two inches in diameter, and perfectly flattened. they are beautifully covered with a cellular reticulation on the thin bark, and show occasional round areoles marking the points of exit of the rootlets. i have long been familiar with irregular flattened stems thus reticulate, but have only recently been able to connect them with this species of calamite. the main stems present a very thin carbonaceous bark reticulated like the rhizomes. they have flat, broad ribs separated by deep and narrow furrows, and undulated in a remarkable manner even when the stems are flattened. this undulation is, however, perhaps an indication of vertical pressure while the plant was living, as it seems to have had an unusually thin and feeble cortical layer, and the undulations are apparently best developed in the lower part of the stem. at the nodes the ribs are often narrowed and gathered together, especially in the vicinity of the rounded radiating marks which appear to indicate the points of insertion of the branches. at the top of each rib we have the usual rounded areole, probably marking the insertion of a primary branchlet. the branches have slender ribs and distant nodes, from which spring secondary branchlet s in whorls, these bearing in turn small whorls of acicular leaflets much curved upward, and which are apparently round in cross section and delicately striate. they are much shorter than the leaves of _calamites suckovii_, and are less dense and less curved than those of _c. nodosus_, which i believe to be the two most closely allied species. lesquereux notices this species as characteristic of the lower part of the carboniferous in arkansas. it will be observed that i regard the striated and ribbed stems not as internal axes, but as representing the outer surface of the plants. this was certainly the case with the present species and with _c. suckovii_ and _c. nodosus_. other species, and especially those which belonged to calamodendron, no doubt had a smooth or irregularly wrinkled external bark; but this gives no good ground for the manner in which some writers on this subject confound calamites with calamodendra, and both with asterophyllites and sphenophyllum. with this no one who has studied these plants, rooted in their native soils, and with their appendages still attached, can for a moment sympathise. one of the earliest geological studies of the writer was a bed of these erect calamites, which he showed to sir c. lyell in , and described in the "proceedings of the geological society" in , illustrating the habit of growth as actually seen well exposed in a sandstone cliff. abundant opportunities of verifying the conclusions formed at that time have since occurred, the results of which have been summed up in the figures in acadian geology, which, though they have been treated by some botanists as merely restorations, are in reality representations of facts actually observed. on these subjects, without entering into details, and referring for these to the elaborate discussions of schimper, williamson, and mcnab, and to my paper on the subject, "journal of the geological society," vol. xxvii, p. , i may remark: . that the aërial stems of ordinary calamites had a thin cortical layer, with lacunæ and fibrous bundles and multiporous vessels--the whole not differing much from the structure of modern equiseta. . certain arborescent forms, perhaps allied to the true calamites, as well as possibly the old underground stems of ordinary species[dc] assumed a thick-walled character in which the tissues resembled the wedges of an exogen, and abundance of pseudo-scalariform fibres were developed, while the ribbing of the external surface became obsolete or was replaced by a mere irregular wrinkling. [dc] williamson, "transactions of the royal society." mcnab, in "proceedings of the edinburgh botanical society." . sufficient discrimination has not been exercised in separating casts of the internal cavities of calamites and calamodendron from those representing other surfaces and the proper external surface. . there is no excuse for attributing to calamites the foliage of annularia, asterophyllites, and sphenophyllum, since these leaves have not been found attached to true calamite stems, and since the structure of the stems of asterophyllites as described by williamson, and that of sphenophyllum as described by the writer,[dd] are essentially different from those of calamites. [dd] "journal of the geological society," . . as the species above described indicates, good external characters can be found for establishing species of this genus, and these species are of value as marks of geological age. _genus_ archæocalamites, sternberg. this genus has been established to include certain calamites of the devonian and lower carboniferous, in which the furrows on the stem do not alternate at the nodes or joints, and the leaves in one species at least bifurcate. _c. radiatus_, brongniart, is the typical species. in north america it occurs in the erian, probably as low as the middle erian. in europe it has so far been recognised in the lower carboniferous only. i have, however, seen stems from alleged devonian beds in devonshire which may have belonged to this species. _family_ asterophylliteæ; _genus_ asterophyllites, brongniart. stems ribbed and jointed like the _calamites_, but with inflated nodes and a stout internal woody cylinder, which has been described by williamson. from the joints proceeded whorls of leaves or of branchlets, bearing leaves which differed from those of _calamites_ in their having a distinct middle rib or vein. the fructification consisted of long slender cones or spikes, having whorls of scales bearing the spore-cases. some authors speak of _asterophyllites_ as only branches and leaves of _calamites_; but though at first sight the resemblance is great, a close inspection shows that the leaves of asterophyllites have a true midrib, which is wanting in _calamites_. _genus_ annularia.--it is perhaps questionable whether these plants should be separated from _asterophyllites_, the distinction is that they produce branches in pairs, and that their whorls of leaves are one-sided and usually broader than those of _asterophyllites_, and united into a ring at their insertion on the stem. one little species, _a. sphenophylloides_, is very widely distributed. pinnularia--a provisional genus---includes slender roots or stems branching in a pinnate manner, and somewhat irregularly. they are very abundant in the coal shales, and were probably not independent plants, but aquatic roots belonging to some of the plants last mentioned. the probability of this is farther increased by their resemblance in miniature to the roots of _calamites_. they are always flattened, but seem originally to have been round, with a slender thread-like axis of scalariform vessels, enclosed in a soft, smooth, cellular bark. _family_ rhizocarpeæ; _genus_ sphenophyllum. leaves in whorls, wedge-shaped, with forking veins. fructification on spikes, with verticils of sporocarps. these plants are by some regarded as allied to the _calamiteæ_ and _asterophylliteæ_, by others as a high grade of rhizocarps of the type of marsilia. the stem had a star-shaped central bundle of scalariform or reticulato-scalariform vessels. _genus_ sporangites. (_sporocarpon_, williamson.) under this name we may provisionally include those rounded spherical bodies found in the coal and its accompanying beds, and also in the erian, which may be regarded as macrospores or sporocarps of protosalvinia, or other rhizocarpean plants akin to those described above in chapter iii, which see for description. _genus_ protosalvinia.--under this we include sporocarps allied to those of _salvinia_, as described in chapter iii. _family_ filices. under this head i shall merely refer to a few groups of special interest, and to the provisional arrangement adopted for the fronds of ferns when destitute of fructification. the external appearances of trunks of tree-ferns have been already referred to. with respect to tree ferns, the oldest known examples are those from the middle devonian of new york and ohio, which i have described in the "journal of the geological society," and . as these are of some interest, i have reproduced their descriptions in a note appended to chapter iii, which see. the other forms most frequently occurring in the carboniferous are _caulopteris_, _palæopteris_, and _megaphyton_[de] stems showing merely masses of aërial roots are known by the name _psaronius_. [de] see my "acadian geology," also below. with reference to the classification of palæozoic ferns, this has hitherto been quite arbitrary, being based on mere form and venation of fronds, but much advance has recently been made in the knowledge of their fructification, warranting a more definite attempt at classification. the following are provisional genera usually adopted: . _cyclopteris_, brongniart.--leaflets more or less rounded or wedge-shaped, without midrib, the nerves spreading from the point of attachment. this group includes a great variety of fronds evidently of different genera, were their fructification known; and some of them probably portions of fronds, the other parts of which may be in the next genus. . _neuropteris_, brongniart.--fronds pinnate, and with the leaflets narrowed at the base; midrib often not distinct, and disappearing toward the apex. nervures equal, and rising at an acute angle. ferns of this type are among the most abundant in the coal-formation. . _odontopteris_, brongniart.--in these the frond is pinnate, and the leaflets are attached by their whole base, with the nerves either proceeding wholly from the base, or in part from an indistinct midrib, which soon divides into nervures. . _dictyopteris_, gutbier.--this is a beautiful style of fern, with leaflets resembling those of _neuropteris_, but the veins arranged in a network of oval spaces. only a few species are known in the coal-formation. . _lonchopteris_, brongniart.--ferns with netted veins like the above, but with a distinct midrib, and the leaflets attached by the whole base. of this, also, we can boast but few species. . _sphenopteris_, brongniart.--these are elegant ferns, very numerous in species, and most difficult to discriminate. their most distinctive characters are leaflets narrowed at the base, often lobed, and with nervures dividing in a pinnate manner from the base. . _phyllopteris_, brongniart.--these are pinnate, with long lanceolate pinnules, having a strong and well-defined midrib, and nerves proceeding from it very obliquely, and dividing as they proceed toward the margin. the ferns of this genus are for the most part found in formations more recent than the carboniferous; but i have referred to it, with some doubt, one of our species. . _alethopteris_, brongniart.--this genus includes many of the most common coal-formation ferns, especially the ubiquitous _a. lonchitica_, which seems to have been the common brake of the coal-formation, corresponding to _pteris aquilina_ in modern europe and america. these are brake-like ferns, pinnate, with leaflets often long and narrow, decurrent on the petiole, adherent by their whole base, and united at base to each other. the midrib is continuous to the point, and the nervures run off from it nearly at right angles. in some of these ferns the fructification is known to have been marginal, as in _pteris_. . _pecopteris_, brongniart.--this genus is intermediate between the last and _neuropteris_. the leaflets are attached by the whole base, but not usually attached to each other; the midrib, though slender, attains to the summit; the nervures are given off less obliquely than in _neuropteris_. this genus includes a large number of our most common fossil ferns. . _beinertia_, goeppert.--a genus established by goeppert for a curious pecopteris-like fern, with flexuous branching oblique nervures becoming parallel to the edge of the frond. . _hymenophyllites_, goeppert.--these are ferns similar to sphenopteris, but divided at the margin into one-nerved lobes, in the manner of the modern genus _hymenophyllum_. . _palæopteris_, geinitz.--this is a genus formed to include certain trunks of tree-ferns with oval transverse scars of leaves. . _caulopteris_, lindley and hutton.--is another genus of fossil trunks of tree-ferns, but with elongate scars of leaves. . _psaronius_, cotta.--includes other trunks of tree-ferns with alternate scars or thick scales, and ordinarily with many aërial roots grouped round them, as in some modern tree-ferns. . _megaphyton_, artis.--includes trunks of tree-ferns which bore their fronds, which were of great size, in two rows, one on each side of the stem. these were very peculiar trees, less like modern ferns than any of the others. my reasons for regarding them as ferns are stated in the following extract from a recent paper: "their thick stems, marked with linear scars and having two rows of large depressed areoles on the sides, suggest no affinities to any known plants. they are usually ranked with _lepidodendron_ and _ulodendron_, but sometimes, and probably with greater reason, are regarded as allied to tree-ferns. at the joggins a very fine species (_m. magnificum_) has been found, and at sydney a smaller species (_m. humile_); but both are rare and not well preserved. if the large scars bore cones and the smaller bore leaves, then, as brongniart remarks, the plant would much resemble _lepidophloios_, in which the cone-scars are thus sometimes distichous. but the scars are not round and marked with radiating scales as in _lepidophloios_; they are reniform or oval, and resemble those of tree-ferns, for which reason they may be regarded as more probably leaf-scars; and in that case the smaller linear scars would indicate ramenta, or small aërial roots. further, the plant described by corda as _zippea disticha_ is evidently a _megaphyton_, and the structure of that species is plainly that of a tree-fern of somewhat peculiar type. on these grounds i incline to the opinion of geinitz that these curious trees were allied to ferns, and bore two rows of large fronds, the trunks being covered with coarse hairs or small aërial roots. at one time i was disposed to suspect that they may have crept along the ground; but a specimen from sydney shows the leaf-stalks proceeding from the stem at an angle so acute that the stem must, i think, have been erect. from the appearance of the scars it is probable that only a pair of fronds were borne at one time at the top of the stem; and, if these were broad and spreading, it would be a very graceful plant. to what extent plants of this type contributed to the accumulation of coal i have no means of ascertaining, their tissues in the state of coal not being distinguishable from those of ferns and _lycopodiaceæ_." . for descriptions of the genus _archæopteris_ and other erian ferns, see chapter iii. chapter v. the flora of the early mesozoic. great physical changes occurred at the close of the carboniferous age. the thick beds of sediment that had been accumulating in long lines along the primitive continents had weighed down the earth's crust. slow subsidence had been proceeding from this cause in the coal-formation period, and at its close vast wrinklings occurred, only surpassed by those of the old laurentian time. hence in the appalachian region of america we have the carboniferous beds thrown into abrupt folds, their shales converted into hard slates, their sandstones into quartzite and their coals into anthracite, and all this before the deposition of the triassic red sandstones which constitute the earliest deposit of the great succeeding mesozoic period. in like manner the coal-fields of wales and elsewhere in western europe have suffered similar treatment, and apparently at the same time. this folding is, however, on both sides of the atlantic limited to a band on the margin of the continents, and to certain interior lines of pressure, while in the middle, as in ohio and illinois in america, and in the great interior plains of europe, the coal-beds are undisturbed and unaltered. in connection with this we have an entire change in the physical character of the deposits, a great elevation of the borders of the continents, and probably a considerable deepening of the seas, leading to the establishment of general geographical conditions which still remain, though they have been temporarily modified by subsequent subsidences and re-elevations. along with this a great change was in progress in vegetable and animal life. the flora and fauna of the palæozoic gradually die out in the permian and are replaced in the succeeding trias by those of the mesozoic time. throughout the permian, however, the remains of the coal-formation flora continue to exist, and some forms, as the _calamites_, even seem to gain in importance, as do also certain types of coniferous trees. the triassic, as well as the permian, was marked by physical disturbances, more especially by great volcanic eruptions discharging vast beds and dykes of lava and layers of volcanic ash and agglomerate. this was the case more especially along the margins of the atlantic, and probably also on those of the pacific. the volcanic sheets and dykes associated with the red sandstones of nova scotia, connecticut, and new jersey are evidences of this. at the close of the permian and beginning of the trias, in the midst of this transition time of physical disturbance, appear the great reptilian forms characteristic of the age of reptiles, and the earliest precursors of the mammals, and at this time the old carboniferous forms of plants finally pass away, to be replaced by a flora scarcely more advanced, though different, and consisting of pines, cycads, and ferns, with gigantic equiseta, which are the successors of the genus _calamites_, a genus which still survives in the early trias. of these groups the conifers, the ferns, and the equiseta are already familiar to us, and, in so far as they are concerned, a botanist who had studied the flora of the carboniferous would have found himself at home in the succeeding period. the cycads are a new introduction. the whole, however, come within the limits of the cryptogams and the gymnosperms, so that here we have no advance.[df] [df] fontaine's "early mesozoic flora of virginia" gives a very good summary of this flora in america. [illustration: fig. .--jurassic vegetation. cycads and pines. (after saporta.)] as we ascend, however, in the mesozoic, we find new and higher types. even within the jurassic epoch, the next in succession to the trias, there are clear indications of the presence of the endogens, in species allied to the screw-pines and grasses; and the palms appear a little later, while a few exogenous trees have left their remains in the lower cretaceous, and in the middle and upper cretaceous these higher plants come in abundantly and in generic forms still extant, so that the dawn of the modern flora belongs to the middle and upper cretaceous. it will thus be convenient to confine ourselves in this chapter to the flora of the earlier mesozoic. passing over for the present the cryptogamous plants already familiar in older deposits, we may notice the new features of gymnospermous and phænogamous life, as they present themselves in this earlier part of the great reptilian age, and as they extended themselves with remarkable uniformity in this period over all parts of the world. for it is a remarkable fact that, if we place together in our collections fossil plants of this period from australia, india, china, siberia, europe, or even from greenland, we find wonderfully little difference in their aspect. this uniformity we have already seen prevailed in the palæozoic flora; and it is perhaps equally marked in that of the mesozoic. still we must bear in mind that some of the plants of these periods, as the ferns and pines, for example, are still world-wide in their distribution; but this does not apply to others, more especially the cycads (fig. ). [illustration: fig. .--_podozamites lanceolatus_, sternb. l. cretaceous.] the cycads constitute a singular and exceptional type in the modern world, and are limited at present to the warmer climates, though very generally distributed in these, as they occur in africa, india, japan, australia, mexico, florida, and the west indies. in the mesozoic age, however, they were world-wide in their distribution, and are found as far north as greenland, though most of the species found in the cretaceous of that country are of small size/ and may have been of low growth, so that they may have been protected by the snows of winter. the cycads have usually simple or unbranching stems, pinnate leaves borne in a crown at top, and fruits which, though somewhat various in structure and arrangement, are all of the simpler form of gymnospermous type. the stems are exogenous in structure, but with slender wood and thick bark, and barred tissue, or properly as tissue intermediate between this and the disc-bearing fibres of the pines. though the cycads have a considerable range of organisation and of fructification, and though some points in reference to the latter might assign them a higher place, on the whole they seem to occupy a lower position than the conifers or the cordaiteæ of the carboniferous. in the carboniferous some of the fern-like leaves assigned to the genus _noeggerathia_ have been shown by stur and weiss to have been gymnosperms, probably allied to cycads, of which they may be regarded at least as precursors. thus the cycadean type does not really constitute an advance in grade of organisation in the mesozoic, any further than that, in the period now in question, it becomes much more developed in number and variety of forms. but the conifers would seem to have had precedence of it for a long time in the palæozoic, and it replaces in the mesozoic the _cordaites_, which in many respects excelled it in complexity. the greater part of the cycads of the mesozoic age would seem to have had short stems and to have constituted the undergrowth of woods in which conifers attained to greater height. an interesting case of this is the celebrated dirt-bed of the quarries of the isle of portland, long ago described by dean buckland. in this fossil soil trunks of pines, which must have attained to great height, are interspersed with the short, thick stems of cycads, of the genus named _cycadoidea_ by buckland, and which from their appearance are called "fossil birds' nests" by the quarrymen. some, however, must have attained a considerable height so as to resemble palms. the cycads, with their simple, thick trunks, usually marked with rhombic scars, and bearing broad spreading crowns of large, elegantly formed pinnate leaves, must have formed a prominent part of the vegetation of the northern hemisphere during the whole of the mesozoic period. a botanist, had there been such a person at the time, would have found this to be the case everywhere from the equator to spitzbergen, and probably in the southern hemisphere as well, and this throughout all the long periods from the early trias to the middle cretaceous. in a paper published in the "linnæan transactions" for , dr. carruthers enumerates twenty species of british mesozoic cycads, and the number might now be considerably increased. [illustration: fig. .--_salisburia_ (gingko) _sibirica_, heer. l. cretaceous, siberia and north america.] the pines present some features of interest. we have already seen their connection with the broad-leaved _cordaites_, and in the permian there are some additional types of broad-leaved coniferæ. in the mesozoic we have great numbers of beautiful trees, with those elegant fan-shaped leaves characteristic of but one living species, the salisburia, or gingko-tree of china. it is curious that this tree, though now limited to eastern asia, will grow, though it rarely fruits, in most parts of temperate europe, and in america as far north as montreal, and that in the mesozoic period it occupied all these regions, and even siberia and greenland, and with many and diversified species (fig. ). _salisburia_ belongs to the yews, but an equally curious fact applies to the cypresses. the genus _sequoia_, limited at present to two species, both californian, and one of them the so-called "big tree," celebrated for the gigantic size to which it attains, is represented by species found as far back at least as the lower cretaceous, and in every part of the northern hemisphere.[dg] it seems to have thriven in all these regions throughout the mesozoic and early kainozoic, and then to have disappeared, leaving only a small remnant to represent it in modern days. a number of species have been described from the mesozoic and tertiary, all of them closely related to those now existing (fig. ). [dg] in the eocene of australia. [illustration: fig. .--_sequoia smithiana_, heer. l. cretaceous.] the following notice of these trees is for the most part translated, with some modifications and abridgment, from a paper read by the late prof. heer before the botanical section of the swiss natural history society: the name itself deserves consideration. it is that of an indian of the cherokee tribe, sequo yah, who invented an alphabet without any aid from the outside world of culture, and taught it to his tribe by writing it upon leaves. this came into general use among the cherokees, before the white man had any knowledge of it; and afterward, in , a periodical was published in this character by the missionaries. sequo yah was banished from his home in alabama, with the rest of his tribe, and settled in new mexico, where he died in . when endlicher was preparing his synopsis of the conifers, in , and had established a number of new genera, dr. jacbon tschudi, then living with endlicher, brought before his notice this remarkable man, and asked him to dedicate this red-wooded tree to the memory of a literary genius so conspicuous among the red men of america. endlicher consented to do so, and only endeavored to make the name pronounceable by changing two of its letters. endlicher founded the genus on the redwood of the americans, _taxodium sempervirens_ of lamb; and named the species _sequoia sempervirens_. these trees form large forests in california, which extend along the coast as far as oregon. trees are there met with of feet in height and feet in diameter. the seeds have been brought to europe a number of years ago, and we already see in upper italy and around the lake of geneva, and in england, high trees; but, on the other hand, they have not proved successful around zurich. in , a second species of sequoia was discovered in california, which, under the name of big tree, soon attained a considerable celebrity. lindley described it, in , as _wellingtonia gigantea_; and, in the following year, decaisne and torrey proved that it belonged to sequoia, and that it accordingly should be called _sequoia gigantea_. while the _sequoia sempervirens_, in spite of the destructiveness of the american lumbermen, still forms large forests along the coast, the _sequoia gigantea_ is confined to the isolated clumps which are met with inland at a height of , to , feet above sea-level, and are much sought after by tourists as one of the wonders of the country. reports came to europe concerning the largest of them which were quite fabulous, but we have received accurate accounts of them from prof. whitney. the tallest tree measured by him has a height of feet, and in the case of one of the trees the number of the rings of growth indicated an age of about , years. it had a girth of to feet. we know only two living species of _sequoia_, both of which are confined to california. the one (_s. sempervirens_) is clothed with erect leaves, arranged in two rows, very much like our yew-tree, and bears small, round cones; the other (_s. gigantea_) has smaller leaves, set closely against the branches, giving the tree more the appearance of the cypress. the cones are egg-shaped, and much larger. these two types are therefore sharply defined. both of these trees have an interesting history. if we go back into the tertiary, this same genus meets us with a long array of species. two of these species correspond to those living at present: the _s. langsdorfii_ to the _s. sempervirens_, and the _s. couttsiæ_ to the _s. gigantea_.[dh] but, while the living species are confined to california, in the tertiary they are spread over several quarters of the globe. [dh] _s. couttsiæ_ has leaves like _s. gigantea_, and cones like those of _ . sempervirens_. let us first consider the _sequoia langsdorfii_. this was first discovered in the lignite of wetterau, and was described as _taxites langsdorfii_. heer found it in the upper rhone district, and there lay beside the twigs the remains of a cone, which showed that the _taxites langsdorfii_ of brongniart belonged to the californian genus sequoia established by endlicher. he afterward found much better preserved cones, together with seeds, along with the plants of east greenland, which fully confirmed the determination. at atanekerdluk in greenland (about ° north latitude) this tree is very common. the leaves, and also the flowers and numerous cones, leave no doubt that it stands very near to the modern redwood. it differs from it, however, in having a much larger number of scales in the cone. the tree is also found in spitzbergen at nearly ° north latitude, where nordenskiöld has collected, at cape lyell, wonderfully preserved branches. from this high latitude the species can be followed down through the whole of europe as far as the middle of italy (at senegaglia, gulf of spezia). in asia, also,, we can follow it to the steppes of kirghisen, to possiet, and to the coast of the sea of japan, and across to alaska and sitka. it is recognized by mr. starkie gardner as one of the species found in the eocene of mull in the hebrides.[di] it is thus known in europe, asia, and america, from ° to ° north latitude, while its most nearly related living species, perhaps even descended from it, is now confined to california. [di] it is _fareites campbelli_ of forbes. with this _s. langsdorfii_, three other tertiary species are nearly related (_s. brevifolia_, hr., _s. disticha_, hr., and _s. nordenskiöldi_, hr.). these have been met with in greenland and spitzbergen, and one of them has lately been found in the united states. three other species, in addition to these, have been described by lesquereux, which appear to belong to the group of the _s. langsdorfii_, viz., _s. longifolia_, lesq., _s. angustifolia_, and _s. acuminata_, lesq. several species also occur in the cretaceous and eocene of canada. these species thus answer to the living _sequoia sempervirens_; but we can also point to tertiary representatives of the _s. gigantea_. their leases are stiff and sharp-pointed, are thinly set round the branches, and lie forward in the same way: the egg-shaped cones are in some cases similar. there are, however, in the early tertiary six species, which fill up the gap between _s. sempervirens_ and _s. gigantea_. they are the _s. couttsiæ_, _s. affinis_, lesq., _s. imbricata_, hr., _s. sibirica_, hr., _s. heerii_, lesq., and _s. biformis_, lesq. of these, _s. couttsiæ_, hr., is the most common and most important species. it has short leaves, lying along the branch, like _s. gigantea_, and small, round cones, like _s. langsdorfii_ and _sempervirens_. bovey tracey in devonshire has afforded splendid specimens of cones, seeds, and twigs, which have been described in the "philosophical transactions." more lately, count saporta has described specimens of cones and twigs from armissan. specimens of this species have also been found in the older tertiary of greenland, so that it must have had a wide range. it is very like to the american _s. affinis_, lesq. in the tertiary there have been already found fourteen well-marked species, which thus include representatives of the two living types, _s. sempervirens_ and _s. gigantea_. we can follow this genus still further back. if we go back to the cretaceous age, we find ten species, of which five occur in the urgon of the lower cretaceous, two in the middle, and three in the upper cretaceous. among these, the lower cretaceous exhibits the two types of the sequoia sempervirens and _s. gigantea_. to the former the _s. smithiana_ answers, and to the latter, the _reichenbachii_, gein. the _s. smithiana_ stands indeed uncommonly near the _s. langsdorfii_, both in the appearance of the leaves on the twigs and in the shape of the cones. these are, however, smaller, and the leaves do not become narrower toward the base. the _s. pectina_, hr., of the upper cretaceous, has its leaves arranged in two rows, and presents a similar appearance. the _s. reichenbachii_ is a type more distinct from those now living and those in the tertiary. it has indeed stiff, pointed leaves, lying forward, but they are arcuate, and the cones are smaller. this tree has been known for a long time, and it serves in the cretaceous as a guiding star, which we can follow from the urgonian of the lower cretaceous up to the cenomanian. it is known in france, belgium, bohemia, saxony, greenland, and spitzbergen (also in canada and the united states). it has been placed in another genus--geinitzia--but we can recognise, by the help of the cones, that it belongs to sequoia. below this, there is found in greenland a nearly related species, the _s. ambigua_, hr., of which the leaves are shorter and broader, and the cones round and somewhat smaller. the connecting link between _s. smithiana_ and _reichenbachii_ is formed by _s. subulata_, hr., and _s. rigida_, hr., and three species (_s. gracilis_, hr., _s. fastigiata_ and _s. gardneriana_, carr.), with leaves lying closely along the branch, and which come very near to the tertiary species _s. couttsiæ_. we have therefore in the cretaceous quite an array of species, which fill up the gap between the _s. sempervirens_ and _gigantea_, and show us that the genus sequoia had already attained a great development in the cretaceous. this was still greater in the tertiary, in which it also reached its maximum of geographical distribution. into the present world the two extremes of the genus have alone continued; the numerous species forming its main body have fallen out in the tertiary. if we look still further back, we find in the jura a great number of conifers, and, among them, we meet in the genus pinus with a type which is highly developed, and which still survives; but for sequoia we have till now looked in vain, so that for the present we can not place the rise of the genus lower than the urgonian of the cretaceous, however remarkable we may think it that in that period it should have developed into so many species; and it is still more surprising that two species already make their appearance which approach so near to the living _sequoia sempervirens_ and _s. gigantea_. altogether, we have become acquainted, up to the present time, with twenty-six species of sequoia. fourteen of these species are found in the arctic zone, and have been described and figured in the "fossil flora of the arctic regions." sequoia has been recognised by ettingshausen even in australia, but there in the eocene. this is, perhaps, the most remarkable record in the whole history of vegetation. the sequoias are the giants of the conifers, the grandest representatives of the family, and the fact that, after spreading over the whole northern hemisphere and attaining to more than twenty specific forms, their decaying remnant should now be confined to one limited region in western america and to two species constitutes a sad memento of departed greatness.[dj] the small remnant of _s. gigantea_ still, however, towers above all competitors, as eminently the "big trees "; but, had they and the allied species failed to escape the tertiary continental submergences and the disasters of the glacial period, this grand genus would have been to us an extinct type. in like manner the survival of the single gingko of eastern asia alone enables us to understand that great series of taxine trees with fern-like leaves of which it is the sole representative. [dj] the writer has shown that much of the material of the great lignite beds of the canadian northwest consists of wood of sequoia of both the modern types. besides these peculiar and now rare forms, we have in the mesozoic many others related closely to existing yews, cypresses, pines, and spruces, so that the conifers were probably in greater abundance and variety than they are at this day. in this period, also, we find the earliest representatives of the endogenous plants. it is true that some plants found in the coal-formation have been doubtfully referred to these, but the earliest certain examples would seem to be some bamboo-like and screw-pine-like plants occurring in the jurassic rocks. some of these are, it is true, doubtful forms, but of others there seems to be no question. the modern _pandanus_ or screw-pine of the tropical regions, which is not a pine, however, but a humble relation of the palms, is a stiffly branching tree, of a candelabra-like form, and with tufts of long leaves on its branches, and nuts or great hard berries for fruit, borne sometimes in large masses, and so protected as to admit of their drifting uninjured on the sea. the stems are supported by masses of aërial roots like those which strengthen the stems of tree-ferns. these structures and habits of growth fit the pandanus for its especial habitat on the shores of tropical islands, to which its masses of nuts are drifted by the winds and currents, and on whose shores it can establish itself by the aid of its aërial roots. some plants referred to the cycads have proved veritable botanical puzzles. one of these, the _williamsonia gigas_ of the english oölite, originally discovered by my friend dr. williamson, and named by him _zamia gigas_, a very tall and beautiful species, found in rocks of this age in various parts of europe, has been claimed by saporta for the endogens, as a plant allied to _pandanus_. some other botanists have supposed the flowers and fruits to be parasites on other plants, like the modern _rafflesia_ of sumatra, but it is possible that after all it may prove to have been an aberrant cycad. the tree-palms are not found earlier than the middle cretaceous, where we shall notice them in the next chapter. in like manner, though a few angiosperms occur in rocks believed to be lower or lower middle cretaceous in greenland and the northwest territory of canada, and in virginia, these are merely precursors of those of the upper cretaceous, and are not sufficient to redeem the earlier cretaceous from being a period of pines and cycads. on the whole, this early mesozoic flora, so far as known to us, has a monotonous and mean appearance. it no doubt formed vast forests of tall pines, perhaps resembling the giant sequoias of california; but they must for the most part have been dark and dismal woods, probably tenanted by few forms of life, for the great reptiles of this age must have preferred the open and sunny coasts, and many of them dwelt in the waters. still we must not be too sure of this. the berries and nuts of the numerous yews and cycads were capable of affording much food. we know that in this age there were many great herbivorous reptiles, like _iguanodon_ and _hadrosaurus_, some of them fitted by their structure to feed upon the leaves and fruits of trees. there were also several kinds of small herbivorous mammals, and much insect life, and it is likely that few of the inhabitants of the mesozoic woods have been preserved as fossils. we may yet have much to learn of the inhabitants of these forests of ferns, cycads, and pines. we must not forget in this connection that in the present day there are large islands, like new zealand, destitute of mammalia, and having a flora comparable with that of the mesozoic in the northern hemisphere, though more varied. we have also the remarkable example of australia, with a much richer flora than that of the early mesozoic, yet inhabited only by non-placental mammals, like those of the mesozoic. the principal legacy that the mesozoic woods have handed down to our time is in some beds of coal, locally important, but of far less extent than those of the carboniferous period. still, in america, the richmond coal-field in virginia is of this age, and so are the anthracite beds of the queen charlotte islands, on the west coast of canada, and the coal of brora in sutherlandshire. valuable beds of coal, probably of this age, also exist in china, india, and south africa; and jet, which is so extensively used for ornament, is principally derived from the carbonised remains of the old mesozoic pines. in the next chapter we have to study a revolution in vegetable life most striking and unique, in the advent of the forest-trees of strictly modern types. note to chapter v. i append to this chapter a table showing the plant-bearing series of the cretaceous and laramie of north america, from a paper in "trans. r. s. c," , which see for further details: (in descending order.) periods. floras and sub-floras. references. --------------+---------------------------+----------------------------- transition upper laramie or porcupine { platanus beds of souris eocene to hill. fort union { river and calgary. report cretaceous. group, u. s. territory. { of geol. survey of canada { for , and memoir of { . --------------+---------------------------+----------------------------- middle laramie or willow creek beds. { lemna and pistia beds of lower laramie or st. { bad lands of th parallel, mary river. { red deer river, &c., with upper { lignites. report th cretaceous { parallel and memoir of { . (danian and senonian). fox hill series marine. fort pierre series marine. { sequoia and brasenia beds belly river { of s. saskatchewan, belly { river, &c. with lignites. { memoir of . coal measures of nanaimo, { memoir of . many b.c., probably here. { dicotyledons, palms, &c. --------------+---------------------------+----------------------------- middle dunvegan series of peace } cretaceous river. dakota group, } memoir of . many (turonian and u. s. amboy clays, } dicotyledons, cycads, &c. cenomanian). u. s. } mill creek beds of rocky { dicotyledonous leaves, mountains. { similar to dakota group of { the u. s. memoir of . --------------+---------------------------+----------------------------- lower suskwa river beds and } cretaceous queen charlotte island } cycads, pines, a few (neocomian. coal series. intermediate } dicotyledons. report geol. &c). beds of rocky } survey. memoir of . mountains. potomac } series of virginia. } kootanie series of rocky { cycads, pines, and ferns. mountains. { memoir of . --------------+---------------------------+------------------------------ chapter vi. the reign of angiosperms in the later cretaceous and kainozoic. [illustration: fig. .--_populus primæva_, heer. cretaceous, of greenland. one of the oldest known angiosperms.] it is a remarkable fact in geological chronology that the culmination of the vegetable kingdom antedates that of the animal. the placental mammals, the highest group of the animal kingdom, are not known till the beginning of the eocene tertiary. the dicotyledonous angiosperms, which correspond to them in the vegetable kingdom, occur far earlier--in the beginning of the upper cretaceous or close of the lower cretaceous. the reign of cycads and pines holds throughout the lower cretaceous, but at the close of that age there is a sudden incoming of the higher plants, and a proportionate decrease, more especially of the cycads. i have already referred to the angiospermous wood supposed to be devonian, but i fear to rest any conclusion on this isolated fact. beyond this, the earliest indications of plants of this class have been found in the lower cretaceous. many years ago heer described and figured the leaves of a poplar (_populus primæva_) from the supposed lower cretaceous of komé, in greenland (fig. ). two species, a _sterculia_ and a _laurus_ or _salix_, occur among fossils described by me in the upper part of the kootanie series of the rocky mountains, and fontaine has recently found in the potomac group of virginia--believed to be of neocomian age--several angiospermous species (_sassafras_, _menispermites_, _sapindus_, _aralia_, _populus_, &c.) mixed with a rich flora of cycads and pines. these are the early forerunners of the modern angiospermous flora; but so far as known they do not occur below the cretaceous, and in its lower portions only very rarely. when, however, we ascend into the upper cretaceous, whether of europe or america, there is a remarkable incoming of the higher plants, under generic forms similar to those now existing. this is, in truth, the advent of the modern flora of the temperate regions of the earth. a very interesting tabular view of its early distribution is given by ward, in the "american journal of science" for , of which the following is a synopsis, with slight emendations. i may add that the new discoveries made since would probably tend to increase the proportionate number of dicotyledons in the newer groups. dicotyledonous trees in the cretaceous. _upper senonian_ species. (fox hill group of america.) _lower senonian_ species. upper white chalk of europe; fort pierre group of america; coal-measures of nanaimo? _turonian_ species. lower white chalk; new jersey marls; belly r. group. _cenomanian._ species. (chalk-marl, greensand, and gault, niobrara and dakota groups of america); dunvegan group of canada; amboy clays of new jersey. _neocomian_ species.[dk] (lower greensand and speeton clay, wealden and hastings sands, kootanie and queen charlotte groups of canada.) [dk] including an estimate of fontaine's undescribed species. thus we have a great and sudden inswarming of the higher plants of modern types at the close of the lower cretaceous. in relation to this, saporta, one of the most enthusiastic of evolutionists, is struck by this phenomenon of the sudden appearance of so many forms, and some of them the most highly differentiated of dicotyledonous plants. the early stages of their evolution may, he thinks, have been obscure and as yet unobserved, or they may have taken place in some separate region, or mother country as yet undiscovered, or they may have been produced by a rapid and unusual multiplication of flower-haunting insects! or it is even conceivable that the apparently sudden elevation of plants may have been due to causes still unknown. this last seems, indeed, the only certain inference in the case, since, as saporta proceeds to say in conclusion: "whatever hypothesis one may prefer, the fact of the rapid multiplication of dicotyledons, and of their simultaneous appearance in a great number of places in the northern hemisphere at the beginning of the cenomanian epoch, cannot be disputed."[dl] [dl] "monde des plantes," p. . the leaves described by heer, from the middle cretaceous of greenland, are those of a poplar (_p. primæva_). those which i have described from a corresponding horizon in the rocky mountains are a _sterculites_ (_s. vetustula_), probably allied to the mallows, and an elongated leaf, _laurophyllum_ (_l. crassinerve_) (fig. ), which may, however, have belonged to a willow rather than a laurel. these are certainly older than the dakota group of the united states and the corresponding formations in canada. on the eastern side of the american continent, in virginia, the potomac series is supposed to be of lower cretaceous age, and here fontaine, as already stated, has found an abundant flora of cycads, conifers, and ferns, with a few angiospermous leaves, which have not yet been described. [illustration: fig. .--_stercalia_ and _laurophyllum_ or salix, the oldest angiosperms known in the cretaceous of canada.] in the canadian rocky mountains, a few hundreds of feet above the beds holding the beforementioned species, are the shales of the mill creek series, rich in many species of dicotyledonous leaves, and corresponding in age with the dakota group, whose fossils have been so well described, first by heer and capellini, and afterward by lesquereux. we may take this dakota group and the quader-sand stone of germany as types of the plant-bearing cenomanian, and may notice the forms occurring in them. in the first place, we recognise here the successors of our old friends, the ferns and the pines, the latter represented by such genera as _taxites_, _sequoia_, _glyptostrobus_, _gingko_, and even _pinus_ itself. we also have a few cycads, but not so dominant as in the previous ages. the fan-palms are well represented, both in america and in the corresponding series in europe, especially by the genus _sabal_, which is the characteristic american type of fan-palm, and there is one genus which saporta regards as intermediate between the fan-palms and the pinnately leaved species. there are also many fragments of stems and leaves of carices and grasses, so that these plants, now so important to the nourishment of man and his companion animals, were already represented. [illustration: fig. .--vegetation of later cretaceous. exogens and palms. (after saporta.)] but the great feature of the time was its dicotyledonous forests, and i have only to enumerate the genera supposed to be represented in order to show the richness of the time in plants of this type. it may be necessary to explain here that the generic names used are mostly based on leaves, and consequently cannot be held as being absolutely certain, since we know that at present one genus may have considerable variety in its leaves, and, on the other hand, that plants of different genera may be very much alike in their foliage. there is, however, undoubtedly a likeness in plan or type of structure in leaves of closely allied plants, and, therefore, if judiciously studied, they can be determined with at least approximate certainty.[dm] more especially we can attain to much certainty when the fruits as well as the leaves are found, and when we can obtain specimens of the wood, showing its structure. such corroboration is not wanting, though unfortunately the leaves of trees are generally found drifted away from the other organs once connected with them. in my own experience, however, i have often found determinations of the leaves of trees confirmed by the discovery of their fruits or of the structure of their stems. thus, in the rich cretaceous plant-beds of the dunvegan series we have beech-nuts associated in the same beds with leaves referred to _fagus_. in the laramie beds i determined many years ago nuts of the _trapa_ or water-chestnut, and subsequently lesquereux found, in beds in the united states, leaves which he referred to the same genus. later, i found in collections made on the red deer river of canada my fruits and lesquereux's leaves on the same slab. the presence of trees of the genera _carya_ and _juglans_ in the same formation was inferred from their leaves, and specimens have since been obtained of silicified wood, with the microscopic structure of the modern butternut. still we are willing to admit that determinations from leaves alone are liable to doubt. [dm] great allowance has to be made for the variability of leaves of the same species. the modern hazel (_c. rostrata_) is a case in point. its leaves, from different parts of the same plant, are so dissimilar in form and size that they might readily be regarded as of different species. in the matter of names of fossil leaves, i sympathise very strongly with dr. nathorst, of stockholm, in his objection to the use of modern generic names for mere leaves, and would be quite content to adopt some non-committal termination, as that of "_phyllum_" or "_ites_" suggested by him. i feel, however, that almost as much is taken for granted if a plant is called corylophyllum or _corylites_, as if called _corylus_. in either case a judgment is expressed as to its affinities, which if wrong under the one term is wrong under the other; and after so much has been done by so many eminent botanists, it seems inexpedient to change the whole nomenclature for so small and questionable an advantage. i wish it, however, to be distinctly understood that plants catalogued on the evidence of leaves alone are for the most part referred to certain genera on grounds necessarily imperfect, and their names are therefore subject to correction, as new facts may be obtained. the more noteworthy modern genera included in the dakota flora, as catalogued by lesquereux, are the following: _liquidambar_, the sweet-gum, is represented both in america and europe, the leaves resembling those of the modern species, but with entire edges, which seems to be a common peculiarity of cretaceous foliage.[dn] _populus_ (poplar), as already stated, appears very early in greenland, and continues with increasing number of species throughout the cretaceous and tertiary. _salix_ (willow) appears only a little later and continues. of the family _cupuliferæ_ we have _fagus_ (beech), _quercus_ (oak), and _castanea_ (chestnut), which appear together in the dakota group and its equivalents. fruits of some of the species are known, and also wood showing structure. _betula_ (birch) is represented by a few species, and specimens of its peculiar bark are also common. _alnus_ (alder) appears in one species at least. the genus plat anus (fig. ), that of the plane-trees, represented at present by one european and one american species, has several species in the cretaceous, though the plane-trees seem to culminate in the early part of the succeeding eocene, where there are several species with immense leaves. the large leaves, known as _credneria_, found in the cenomanian of europe, and those called _protophyllum_ (fig. ) in america, appear to be nearer to the plane-trees than to any others, though representing an extinct type. the laurels are represented in this age, and the american genus sassafras, which has now only one species, has not one merely but several species in the cretaceous. _diospyros_, the persimmon-tree, was also a cretaceous genus. [dn] with reference to this, something may be learned from the leaves of modern trees. in these, young shoots have leaves often less toothed and serrated than those of the adult tree. a remarkable instance is the _populus grandidentatus_ of america, the young shoots of which have entire leaves, quite unlike except in venation those of the parent tree, and having an aspect very similar to that of the cretaceous poplars. [illustration: fig. .--_platanus nobilis_, newberry, variety _basilobata_. laramie. much reduced.] [illustration: fig. .--_protophyllum boreale_, dawson, reduced. upper cretaceous, canada.] the single species of the beautiful _liriodendron_, or tulip-tree, is a remnant of a genus which had several cretaceous species (figs. , ). the magnolias, still well represented in the american flora, were equally plentiful in the cretaceous (fig. ). the walnut family were well represented by species of _juglans_ (butternut) and _carya_, or hickory. in all, no less than forty-eight genera are present belonging to at least twenty-five families, running through the whole range of the dicotyledonous exogens. this is a remarkable result, indicating a sudden profusion of forms of these plants of a very striking character. it is further to be observed that some of the genera have many species in the cretaceous and dwindle toward the modern. in others the reverse is the case--they have expanded in modern times. in a number there seems to have been little change. [illustration: fig. .--_magnolia magnifica_, dawson, reduced. upper cretaceous, canada.] dr. newberry has given, in the "bulletin of the torrey botanical club" an interesting _résumé_ of the history of the beautiful _liriodendron_, or tulip-tree, which may be taken as an example of a genus which has gone down in importance in the course of its geological history. "the genus _liriodendron_, as all botanists know, is represented in the present flora by a single species, 'the tulip-tree' which is confined to eastern america, but grows over all the area lying between the lakes and the gulf, the mississippi and the atlantic. it is a magnificent tree, on the whole, the finest in our forests. its cylindrical trunk, sometimes ten feet in diameter, carries it beyond all its associates in size, while the beauty of its glossy, lyre-shaped leaves and tulip-like flowers is only surpassed by the flowers and foliage of its first cousin, _magnolia grandiflora_. that a plant so splendid should stand quite alone in the vegetation of the present day excited the wonder of the earlier botanists, but the sassafras, the sweet-gum, and the great sequoias of the far west afford similar examples of isolation, and the latter are still more striking illustrations of solitary grandeur." (figs. and .) [illustration: fig. .--_liriodendron meekii_, heer. (after lesquereux.)] [illustration: fig. .--_liriodendron primævum_, newberry. (after newberry.)] "three species of _liriodendron_ are indicated by leaves found in the amboy clays--middle cretaceous--of new jersey, and others have been obtained from the dakota group in the west, and from the upper cretaceous strata of greenland. though differing considerably among themselves in size and form, all these have the deep sinus of the upper extremity so characteristic of the genus, and the nervation is also essentially the same. hence, we must conclude that the genus _liriodendron_, now represented by a single species, was in the cretaceous age much more largely developed, having many species, and those scattered throughout many lands. in the tertiary age the genus continued to exist, but the species seem to have been reduced to one, which is hardly to be distinguished from that now living. in many parts of europe leaves of the tulip-tree have been found, and it extended as far south as italy. its presence there was first made known by unger, in his 'synopsis,' page , and in his 'genera et species,' page , where he describes it under the name of _liriodendron procaccinii_. the genus has also been noticed in europe by massalongo, heer, and ettingshausen, and three species have been distinguished. all these are, however, so much like the living species that they should probably be united with it. we here have a striking illustration of the wide distribution of a species which has retained its characters both of fruit and leaf quite unchanged through long migrations and an enormous lapse of time. "in europe the tulip-tree, like many of its american associates, seems to have been destroyed by the cold of the ice period, the mediterranean cutting off its retreat, but in america it migrated southward over the southern extension of the continent and returned northward again with the amelioration of the climate." leaves of _liriodendron_ have been recognised in the cretaceous of greenland, though it is now a tree of the warm temperate region, and lesquereux describes several species from the dakota group. but the genus has not yet been recognised in the laramie or in the upper cretaceous of british columbia. in the paper above quoted, newberry describes three new species from the amboy clays, one of which he considers identical with a greenland form referred by heer to _l. meekii_ of the dakota group. thus, if all lesquereux's species are to be accepted, the genus begins in the middle cretaceous with at least nine american species. in new jersey the amboy clays are referred to the same age with the dakota beds of the west. in these dr. newberry has found a rich flora, including many angiosperms. the following is condensed from a preliminary notice in the "bulletin of the torrey botanical club":[do] [do] march, . "the flora of the amboy clays is closely related to that of the dakota group--most of the genera and some of the species being identical--so that we may conclude they were nearly contemporaneous, though the absence in new jersey of the fort benton and niobrara groups of the upper missouri and the apparent synchronism of the new jersey marls and the pierre group indicate that the dakota is a little the older. "at least one-third of the species of the amboy clays seem to be identical with leaves found in the upper cretaceous clays of greenland and aachen (aix la chapelle), which not only indicates a chronological parallelism, but shows a remarkable and unexpected similarity in the vegetation of these widely separated countries in the middle and last half of the cretaceous age. the botanical character of the flora of the amboy clays will be seen from the following brief synopsis: "_algæ._--a small and delicate form, allied to chondrites. "_ferns._--twelve species, generally similar and in part identical with those described by heer from the cretaceous beds of greenland, and referred to the genera _dicksonia_, _gleichenia_, and _aspidium_. "_cycads._--two species, probably identical with the forms from greenland described by heer under the names of _podozamites marginatus_ and _p. tenuinervis_. "_conifers._--fourteen species, belonging to the genera _moriconia_, _brachyphyllum_, _cunninghamites_, _pinus_, _sequoia_, and others referred by heer to _juniperus_, _libocedrus_, _frenelopsis_, _thuya_, and _dammara_. of these, the most abundant and most interesting are _moriconia cyclotoxon_--the most beautiful of conifers--and _cunninghamites elegans_, both of which occur in the cretaceous clays of aachen, prussia, and patoot, greenland. the _brachyphyllum_ was a large and strong species, with imbricated cones, eight inches in length. "the angiosperms form about seventy species, which include three of _magnolia_, four of _liriodendron_, three or four of _salix_, three of _celastrophyllum_ (of which one is identical with a greenland species), one _celastrus_ (also found in greenland), four or five _aralias_, two _sassafras_, one _cinnamomum_, one _hedera_; with leaves that are apparently identical with those described by heer as belonging to _andromeda_, _cissites_, _cornus_, _dewalquea_, _diospyros_, _eucalyptus_, _ficus_, _ilex_, _juglans_, _laurus_, _menispermites_, _myrica_, _myrsine_, _prunus_, _rhamnus_, and others not yet determined. "some of the aralias had palmately-lobed leaves, nearly a foot in diameter, and two of the tulip-trees (_liriodendron_) had leaves quite as large as those of the living species. one of these had deeply lobed leaves, like those of the white oak. of the other, the leaves resembled those of the recent tulip-tree, but were larger. both had the peculiar emargination and the nervation of _liriodendron_. "among the most interesting plants of the collection are fine species of _bauhinia_ and _hymenæa_. of these, the first is represented by a large number of leaves, some of which are six or seven inches in diameter. they are deeply bilobed, and have the peculiar and characteristic form and nervation of the leaves of this genus. _bauhinia_ is a leguminous genus allied to _cercis_, and now inhabits tropical and warm temperate climates in both hemispheres. only one species occurs in the united states, _bauhinia lunarioides_, gray, found by dr. bigelow on the rio grande. "_hymenæa_ is another of the leguminosæ, and inhabits tropical america. a species of this genus has been found in the upper cretaceous of france, but quite different from the one before us, in which the leaves are much larger, and the leaflets are united in a common petiole, which is winged; this is a modification not found in the living species, and one which brings it nearer to _bauhinia_. "but the most surprising discovery yet made is that of a number of quite large helianthoid flowers, which i have called _palæanthus_. these are three to four inches in diameter, and exhibit a scaly involucre, enclosing what much resembles a fleshy receptacle with achenia. from the border of this radiate a number of ray florets, one to two inches in length, which are persistent and must have been scarious, like those of _helichrysum_. though these flowers so much resemble those of the compositæ, we are not yet warranted in asserting that such is certainly their character. in the jurassic rocks of europe and india some flowers not very unlike these have been found, which have been named _williamsonia_, and referred to cycads by carruthers. a similar fossil has been found in the cretaceous rocks of greenland, and named by heer _williamsonia cretacea_, but he questions the reference of the genus to the cycadeæ, and agrees with nathorst in considering all the species of _williamsonia_ as parasitic flowers, allied to _brugmansia_ or _rafflesia_. the marquis of saporta regards them as monocotyledons, similar to _pandanus_. more specimens of the flowers now exhibited will perhaps prove--what we can now only regard as probable--that the compositæ, like the _leguminosæ_, _magnoliaceæ_, _celastraceæ_, and other highly organised plants, formed part of the cretaceous flora. no composite flowers have before been found in the fossil state, and, as these are among the most complex and specialised forms of florescence, it has been supposed that they belonged only to the recent epoch, where they were the result of a long series of formative changes." the above presents some interesting new types not heretofore found in the middle cretaceous. more especially the occurrence of large flowers of the composite type presents a startling illustration of the early appearance of a very elevated and complex form. great interest also attaches to these amboy beds, as serving, with those of aix and greenland, to show that the margins of the atlantic were occupied with a flora similar to that occurring at the same time in the interior plateau of north america and on the pacific slope. the beds at aix-la-chapelle are, however, probably somewhat newer than the dakota or amboy beds, and correspond more nearly in age with those of the cretaceous coal-field of vancouver island, where there is a very rich upper cretaceous flora, which i have noticed in detail in the "transactions of the royal society of canada."[dp] in these upper cretaceous beds there are fan-palms as far north at least as the latitude of °, indicating a very mild climate at this period. this inference is corroborated by the upper cretaceous flora of atané and patoot in greenland, as described by heer. [dp] vol. ii., . the dicotyledonous plants above referred to are trees and shrubs. of the herbaceous exogens of the period we know less. obviously their leaves are less likely to find their way into aqueous deposits than the leaves of trees. they are, besides, more perishable, and in densely wooded countries there are comparatively few herbaceous plants. i have examined the beds of mud deposited at the mouth of a woodland streamlet, and have found them stored with the fallen leaves of trees, but it was in vain to search for the leaves of herbaceous plants. [illustration: fig. .--_brasenia antiqua_. upper cretaceous, south saskatchewan river. natural size, _a_, _b_, diagrams of venation, slightly enlarged.] the climate of north america and europe, represented by the cenomanian vegetation, is not tropical but warm temperate; but the flora was more uniform than at present, indicating a very equable climate and the possibility of temperate genera existing within the arctic circle, and it would seem to have become warmer toward the close of the period. the flora of the cenomanian is separated in most countries from that of the senonian, or uppermost cretaceous, by a marine formation holding few plants. this depends on great movements of elevation and depression, to which we must refer in the sequel. in a few regions, however, as in the vicinity of the peace river in canada, there are plant-bearing beds which serve to bridge over the interval between the early cenomanian and the later cretaceous.[dq] [dq] see paper by the author in the "transactions of the royal society of canada," . to this interval also would seem to belong the belly river series of western canada, which contains important beds of coal, but is closely associated with the marine fort pierre series. a very curious herbaceous plant of this group, which i have named _brasenia antiqua_, occurs in the beds associated with one of the coals. it is a close ally of the modern _b. peltata_, an aquatic plant which occurs in british columbia and in eastern america, and is also said to be found in japan, australia, and india, a width of distribution appropriate to so old a type (fig. ). in so far as vegetable life is concerned, the transition from the upper cretaceous to the tertiary or kainozoic is easy, though in many parts of the world, and more especially in western europe, there is a great gap in the deposits between the upper chalk and the lowest eocene. with reference to fossil plants, schimper recognises in the kainozoic, beginning with the oldest, five formations--palæocene, eocene, oligocene, miocene, and pliocene. throughout these a flora, similar to that of the cretaceous on the one hand and the modern on the other, though with important local peculiarities, extends. there is evidence, however, of a gradual refrigeration, so that in the pliocene the climates of the northern hemisphere were not markedly different from their present character. in the first instance an important error was committed by palæobotanists, in referring to the miocene many deposits really belonging to the eocene. this arose from the early study of the rich plant-bearing miocene beds of switzerland, and from the similarity of the flora all the way from the middle cretaceous to the later tertiary. the differences are now being worked out, and we owe to mr. starkie gardner the credit of pointing these out in england, and to the geological survey of canada that of collecting the material for exhibiting them in the more northern part of america. in the great interior plain of america there rests on the cretaceous a series of clays and sandstones with beds of lignite, some of them eighteen feet in thickness. this was formerly known as the lignitic or lignite tertiary, but more recently as the laramie series. these beds were deposited in fresh or brackish water, in an internal sea or group of lakes and swamps, when the continent was lower than at present. they have been studied both in the united states[dr] and canada; and, though their flora was originally referred by mistake to the miocene, it is now known to be eocene or palæocene, or even in part a transition group between the latter and the cretaceous. the following remarks, taken chiefly from recent papers by the author,[ds] will serve to illustrate this: [dr] see more especially the elaborate and valuable reports by lesquereux and newberry, and a recent memoir by ward on "types of the laramie flora," "bulletins of the united states geological survey," . [ds] "transactions of the royal society of canada," -' . on the geological map of canada the laramie series, formerly known as the lignitic or lignite tertiary, occurs, with the exception of a few outliers, in two large areas west of the th meridian, and separated from each other by a tract of older cretaceous rocks, over which the laramie beds may have extended, before the later denudation of the region. the most eastern of these areas, that of the souris river and wood mountain, extends for some distance along the united states boundary, between the d and th meridians, and reaches northward to about thirty miles south of the "elbow" of the south saskatchewan river, which is on the parallel of ° north. in this area the lowest beds of the laramie are seen to rest on those of the fox hill group of the upper cretaceous, and at one point on the west they are overlaid by beds of miocene tertiary age, observed by mr. mcconnell, of the geological survey, in the cypress hills, and referred by cope, on the evidence of mammalian remains, to the white river division of the united states geologists, which is regarded by them as lower miocene.[dt] the age of the laramie beds is thus stratigraphically determined to be between the fox hill cretaceous and the lower miocene. they are also undoubtedly continuous with the fort union group of the united states geologists on the other side of the international boundary, and they contain similar fossil plants. they are divisible into two groups--a lower, mostly argillaceous, and to which the name of "bad lands beds" may be given, from the "bad lands" of wood mountain, where they are well exposed, and an upper, partly arenaceous member, which may be named the souris river or porcupine creek division. in the lower division are found reptilian remains of upper cretaceous type, with some fish remains more nearly akin to those of the eocene.[du] neither division has as yet afforded mammalian remains. [dt] "report of the geological survey of canada," . [du] cope, in dr. g. m. dawson's "report on the th parallel." the western area is of still larger dimensions, and extends along the eastern base of the rocky mountains from the united states boundary to about the th parallel of latitude, and stretches eastward to the th meridian. in this area, and more especially in its southern part, the officers of the geological survey of canada have recognised three divisions, as follows: ( ) the lower laramie or st. mary river series, corresponding in its character and fossils to the lower or bad lands division of the other area. ( ) a middle division, the willow creek beds, consisting of clays, mostly reddish, and not recognised in the other area. ( ) the upper laramie or porcupine hills division, corresponding in fossils, and to some extent in mineral character, to the souris river beds of the eastern area. the fossil plants collected by dr. g. m. dawson in the eastern area were noticed by the author in an appendix to dr. dawson's report on the th parallel, in , and a collection subsequently made by dr. selwyn was described in the "report of the geological survey of canada" for -' . those of the western area, and especially collections made by myself near calgary in , and by officers of the geological survey in , have been described in the "transactions of the royal society of canada" vols. iii. and iv. in studying these fossil plants, i have found that there is a close correspondence between those of the lower and upper laramie in the two areas above referred to respectively, and that the flora of the lower laramie is somewhat distinct from that of the upper, the former being especially rich in certain aquatic plants, and the latter much more copious on the whole, and much more rich in remains of forest-trees. this is, however, possibly an effect rather of local conditions than of any considerable change in the flora, since some upper laramie forms recur as low as the belly river series of the cretaceous, which is believed on stratigraphical grounds to be considerably older than the lower laramie. with reference to the correlation of these beds with those of the united states, some difficulty has arisen from the tendency of palæobotanists to refer the plants of the upper laramie to the miocene age, although in the reports of mr. clarence king, the late director of the united states geological survey, these beds are classed, on the evidence of stratigraphy and animal fossils, as upper cretaceous. more recently, however, and partly perhaps in consequence of the views maintained by the writer since , some change of opinion has occurred, and dr. newberry and mr. lesquereux seem now inclined to admit that what in canada we recognise as upper laramie is really eocene, and the lower laramie either cretaceous or a transition group between this and the eocene. in a recent paper [dv] dr. newberry gives a comparative table, in which he correlates the lower laramie with the upper cretaceous of vancouver island and the faxoe and maestricht beds of europe, while he regards the upper laramie as equivalent to european eocene. except in so far as the equivalence of the lower laramie and vancouver island beds is concerned, this corresponds very nearly with the conclusions of the writer in a paper published last year[dw]--namely, that we must either regard the laramie as a transition cretaceo-eocene group, or must institute our line of separation in the willow creek or middle laramie division, which has, however, as yet afforded no fossil plants. i doubt, however, the equivalence of the vancouver beds and the lower laramie, except perhaps in so far as the upper member of the former is concerned. i have also to observe that in the latest report of mr. lesquereux he still seems to retain in the miocene certain formations in the west, which from their fossil plants i should be inclined to regard as eocene.[dx] [dv] newberry, "transactions of the new fork academy," february, . [dw] "transactions of the royal society of canada," vol. ii. [dx] while these sheets were going through the press i received a very valuable report of mr. lester f. ward upon the laramie of the united states. i have merely had time to glance at this report, but can see that the views of the author agree closely with those above expressed. two ferns occurring in these beds are remarkable as evidence of the persistence of species, and of the peculiarities of their ancient and modern distribution. _onoclea sensibilis_, the very common sensitive fern of eastern america, is extremely abundant in the laramie beds over a great area in the west. mr. starkie gardner and dr. newberry have also shown that it is identical with the _filicites hebridicus_ of forbes, from the early eocene beds of the island of mull, in scotland. thus we have a species once common to europe and america, but now restricted to the latter, and which has continued to exist over all the vast ages between the cretaceous and the present day. in the laramie beds i have found associated with this species another and more delicate fern, the modern _davallia_ (_stenloma_) _tenuifolia_, but this, unlike its companion, no longer occurs in america, but is found in the mountains of asia. this is a curious illustration of the fact that frail and delicate plants may be more ancient than the mountains or plains on which they live. there are also some very interesting and curious facts in connection with the conifers of the laramie. one of the most common of these is a _thuja_ or arbor vitæ (the so-called "cedar" of canada). the laramie species has been named _t. interrupta_ by newberry, but it approaches very closely in its foliage to _t. occidentalis_, of eastern canada, while its fruit resembles that of the western species, _t. gigantea_. still more remarkable are the sequoias to which we have already referred, but which in the laramie age seem to have been spread over nearly all north america. the fossil species are of two types, representing respectively the modern _s. gigantea_ and _s. sempervirens_, and their wood, as well as that of thuja, is found in great abundance in the lignites, and also in the form of silicified trunks, and corresponds with that of the recent species. the laramie contains also conifers of the genera _glyptostrobus_, _taxodium_, and _taxus_; and the genus _salisburia_ or gingko--so characteristic of the jurassic and cretaceous--is still represented in america as well as in europe in the early eocene. we have no palms in the canadian or scottish palæocene, though i believe they are found further south. the dicotyledonous trees are richly represented. perhaps the most conspicuous were three species of _platanus_, the leaves of which sometimes fill the sandstones, and one of which, _p. nobilis_, newberry, sometimes attains the gigantic size of a foot or more in diameter of its blade. the hazels are represented by a large-leaved species, _c. macquarrii_, and by leaves not distinguishable from those of the modern american species, _c. americana_ and _c. rostrata_. there are also chestnuts and oaks. but the poplars and willows are specially abundant, being represented by no less than six species, and it would seem that all the modern types of poplar, as indicated by the forms and venation of the leaves, existed already in the laramie, and most of them even in the upper cretaceous. _sassafras_ is represented by two species, and the beautiful group of _viburnum_,, to which the modern tree-cranberry belongs, has several fine species, of some of which both leaves and berries have been found. the hickories and butternuts are also present, the horse-chestnut, the _catalpa_ and _sapindus_, and some curious leaves which seem to indicate the presence of the modern genus _symphorocarpus_, the snow-berry tribe. the above may suffice to give an idea of the flora of the older eocene in north america, and i may refer for details to the works of newberry, lesquereux, and ward, already cited. i must now add that the so-called miocene of atanekerdluk, greenland, is really of the same age, as also the "miocene" of mull, in scotland, of antrim, in ireland, and of bovey tracey, in the south of england, and the gelinden, or "heersian" beds, of belgium, described by saporta. in comparing the american specimens with the descriptions given by gardner of the leaf-beds at ardtown, in mull, we find, as already stated, _onoclea sensibilis_, common to both. the species of _sequoia_, _gingko_, _taxus_, and _glyptostrobus_ are also identical or closely allied, and so are many of the dicotyledonous leaves. for example, _platanoides hebridicus_ is very near to _p. nobilis_, and _corylus macquarrii_ is common to both formations, as well as _populus arctica_ and _p. richardsoni_. i may add that ever since -' , when i first studied the laramie plants, i have maintained their identity with those of the fort union group of the united states, and of the so-called miocene of mckenzie river and greenland, and that the whole are paleocene; and this conclusion has now been confirmed by the researches of gardner in england, and by the discovery of true lower miocene beds in the canadian northwest, overlying the laramie or lignite series. in a bulletin of the united states geological survey ( ), dr. white has established in the west the continuous stratigraphical succession of the laramie and the wahsatch eocene, thus placing the laramie conformably below the lower eocene of that region. cope has also described as the puerta group a series of beds holding vertebrate fossils, and forming a transition from the laramie to the wahsatch. white also testifies that a number of fresh-water mollusks are common to the wahsatch and the laramie. this finally settles the position of the laramie so far as the united states geologists are concerned, and shows that the flora is to be regarded as eocene if not upper cretaceous, in harmony with what has been all along maintained in canada. an important _résumé_ of the flora has just been issued by ward in the bulletins of the united states geological survey ( ). before leaving this part of the subject, i would deprecate the remark, which i see occasionally made, that fossil plants are of little value in determining geological horizons in the cretaceous and tertiary. i admit that in these periods some allowance must be made for local differences of station, and also that there is a generic sameness in the flora of the northern hemisphere, from the cenomanian to the modern, yet these local differences and general similarity are not of a nature to invalidate inferences as to age. no doubt, so long as palæobotanists seemed obliged, in deference to authority, and to the results of investigations limited to a few european localities, to group together, without distinction, all the floras of the later cretaceous and earlier tertiary, irrespective of stratigraphical considerations, the subject lost its geological importance. but, when a good series has been obtained in any one region of some extent, the case becomes different. though there is still much imperfection in our knowledge of the cretaceous and tertiary floras of canada, i think the work already done is sufficient to enable any competent observer to distinguish by their fossil plants the lower, middle, and upper cretaceous, and the latter from the tertiary; and, with the aid of the work already done by lesquereux and newberry in the united states, to refer approximately to its true geological position any group of plants from beds of unknown age in the west. an important consequence arising from the above statements is that the period of warm climate which enabled a temperate flora to exist in greenland was that of the later cretaceous and early eocene rather than, as usually stated, the miocene. it is also a question admitting of discussion whether the eocene flora of latitudes so different as those of greenland, mackenzie river, northwest canada, and the united states, were strictly contemporaneous, or successive within a long geological period in which climatal changes were gradually proceeding. the latter statement must apply at least to the beginning and close of the period; but the plants themselves have something to say in favour of contemporaneity. the flora of the laramie is not a tropical but a temperate flora, showing no doubt that a much more equable climate prevailed in the more northern parts of america than at present. but this equability of climate implies the possibility of a great geographical range on the part of plants. thus it is quite possible and indeed highly probable that in the laramie age a somewhat uniform flora extended from the arctic seas through the great central plateau of america far to the south, and in like manner along the western coast of europe. it is also to be observed that, as gardner points out, there are some differences indicating a diversity of climate between greenland and england, and even between scotland and ireland and the south of england, and we have similar differences, though not strongly-marked, between the laramie of northern canada and that of the united states. when all our beds of this age from the arctic sea to the th parallel have been ransacked for plants, and when the palæobotanists of the united states shall have succeeded in unravelling the confusion which now exists between their laramie and the middle tertiary, the geologist of the future will be able to restore with much certainty the distribution of the vast forests which in the early eocene covered the now bare plains of interior america. further, since the break which in western europe separates the flora of the cretaceous from that of the eocene does not exist in america, it will then be possible to trace the succession from the mesozoic flora of the trias and of the queen charlotte islands and kootanie series of the lower cretaceous up to the close of the eocene; and to determine, for america at least, the manner and conditions under which the angiospermous flora of the later cretaceous succeeded to the pines and cycads which characterised the beginning of the cretaceous period. in so far as europe is concerned, this may be more difficult, since the want of continuity of land from north to south seems there to have been fatal to the continuance of some plants during changes of climate, and there were also apparently in the kainozoic period invasions at certain times of species from the south and east, which did not occur to the same extent in america. in recent reports on the tertiary floras of australia and new zealand,[dy] ettingshausen holds that the flora of the tertiary, as a whole, was of a generalised character; forms now confined to the southern and northern hemispheres respectively being then common to both. it would thus seem that the present geographical diversities must have largely arisen from the great changes in climate and distribution of land and water in the later tertiary. [dy] "geological magazine," august, . the length of our discussion of the early angiospermous flora does not permit us to trace it in detail through the miocene and pliocene, but we may notice the connection through these in the next chapter, and may refer to the magnificent publications of heer and lesquereux on the tertiary floras of europe and america respectively. chapter vii. plants from the tertiary to the modern period. it may be well to begin this chapter with a sketch of the general physical and geological conditions of the period which was characterised by the advent and culmination of the dicotyledonous trees. in the jurassic and earliest cretaceous periods the prevalence, over the whole of the northern hemisphere and for a long time, of a monotonous assemblage of gymnospermous and acrogenous plants, implies a uniform and mild climate, and facility for intercommunication in the north. toward the end of the jurassic and beginning of the cretaceous, the land of the northern hemisphere was assuming greater dimensions, and the climate probably becoming a little less uniform. before the close of the lower cretaceous period the dicotyledonous flora seems to have been introduced, under geographical conditions which permitted a warm temperate climate to extend as far north as greenland. in the cenomanian or middle cretaceous age we find the northern hemisphere tenanted with dicotyledonous trees closely allied to those of modern times, though still indicating a climate much warmer than that which at present prevails. in this age, extensive but gradual submergence of land is indicated by the prevalence of chalk and marine limestones over the surface of both continents; but a circumpolar belt seems to have been maintained, protecting the atlantic and pacific basins from floating ice, and permitting a temperate flora of great richness to prevail far to the north, and especially along the southern margins and extensions of the circumpolar land. these seem to have been the physical conditions which terminated the existence of the old mesozoic flora and introduced that of the middle cretaceous. as time advanced the quantity of land gradually increased, and the extension of new plains along the older ridges of land was coincident with the deposition of the great laramie series, and with the origination of its peculiar flora, which indicates a mild climate and considerable variety of station in mountain, plain, and swamp, as well as in great sheets of shallow and weedy fresh water. in the eocene and miocene periods, the continents gradually assumed their present form, and the vegetation became still more modern in aspect. in that period of the eocene, however, in which the great nummulitic limestones were deposited, a submergence of land occurred on the eastern continent which must have assimilated its physical conditions to those of the middle cretaceous. this great change, affecting materially the flora of europe, was not equally great in america, which also by the north and south extension of its mountain-chains permitted movements of migration not possible in the old world. from the eocene downward, the remains of land-animals and plants are found chiefly in lake-basins occupying the existing depressions of the land, though more extensive than those now remaining. it must also be borne in mind that the great foldings and fractures of the crust of the earth which occurred at the close of the eocene, and to which the final elevation of such ranges as the alps and the rocky mountains belongs, permanently modified and moulded the forms of the continents. these statements raise, however, questions as to the precise equivalence in time of similar floras found in different latitudes. however equable the climate, there must have been some appreciable difference in proceeding from north to south. if, therefore, as seems in every way probable, the new species of plants originated on the arctic land and spread themselves southward, this latter process would occur most naturally in times of gradual refrigeration or of the access of a more extreme climate--that is, in times of the elevation of land in the temperate latitudes, or, conversely, of local depression of land in the arctic, leading to invasions of northern ice. hence, the times of the prevalence of particular types of plants in the far north would precede those of their extension to the south, and a flora found fossil in greenland might be supposed to be somewhat older than a similar flora when found farther south. it would seem, however, that the time required for the extension of a new flora to its extreme geographical limit is so small, in comparison with the duration of an entire geological period, that, practically, this difference is of little moment, or at least does not amount to antedating the arctic flora of a particular type by a whole period, but only by a fraction of such period. it does not appear that, during the whole of the cretaceous and eocene periods, there is any evidence of such refrigeration as seriously to interfere with the flora, but perhaps the times of most considerable warmth are those of the dunvegan group in the middle cretaceous, and those of the later laramie and oldest eocene. it would appear that no cause for the mild temperature of the cretaceous needs to be invoked, other than those mutations of land and water which the geological deposits themselves indicate. a condition, for example, of the atlantic basin in which the high land of greenland should be reduced in elevation, and at the same time the northern inlets of the atlantic closed against the invasion of arctic ice, would at once restore climatic conditions allowing of the growth of a temperate flora in greenland. as dr. brown has shown,[dz] and as i have elsewhere argued, the absence of light in the arctic winter is no disadvantage, since, during the winter, the growth of deciduous trees is in any case suspended; while the constant continuance of light in the summer is, on the contrary, a very great stimulus and advantage. [dz] "florula discoana." it is a remarkable phenomenon in the history of genera of plants in the later mesozoic and tertiary, that the older genera appear at once in a great number of specific types, which become reduced as well as limited in range down to the modern. this is, no doubt, connected with the greater differentiation of local conditions in the modern; but it indicates also a law of rapid multiplication of species in the early life of genera. the distribution of the species of _salisburia_, _sequoia_, _platanus_, _sassafras_, _liriodendron_, _magnolia_, and many other genera, affords remarkable proofs of this. gray, saporta, heer, newberry, lesquereux, and starkie gardner have all ably discussed these points; but the continual increase of our knowledge of the several floras, and the removal of error as to the dates of their appearance, must greatly conduce to clearer and more definite ideas. in particular, the prevailing opinion that the miocene was the period of the greatest extension of warmth and of a temperate flora into the arctic, must be abandoned in favour of the later cretaceous and eocene; and, if i mistake not, this will be found to accord better with the evidence of general geology and of animal fossils. in these various revolutions of the later cretaceous and kainozoic periods, america, as dr. gray has well pointed out, has had the advantage of a continuous stretch of high land from north to south, affording a more sure refuge to plants in times of submergence, and means of escape to the south in times of refrigeration. hence, the greater continuity of american vegetation and the survival of genera like _sequoia_ and _liriodendron_, which have perished in the old world. still, there are some exceptions to this, for the gingko-tree is a case of survival in asia of a type once plentiful in america, but now extinct there. eastern asia has had, however, some considerable share of the same advantage possessed by america, with the addition, referred to by gray, of a better and more insular climate. but our survey of these physical conditions can not be considered complete till we shall have considered the great glacial age of the pleistocene. it is certain that throughout the later miocene and pliocene the area of land in the northern hemisphere was increasing, and the large and varied continents were tenanted by the noblest vegetation and the grandest forms of mammalian life that the earth has ever witnessed. as the pliocene drew to a close, a gradual diminution of warmth came on, and more especially a less equable climate, and this was accompanied with a subsidence of the land in the temperate regions and with changes of the warm ocean-currents. thus gradually the summers became cooler and the winters longer and more severe, the hill-tops became covered with permanent snows, glaciers ploughed their way downward into the plains, and masses and fields of floating ice cooled the seas. in these circumstances the richer and more delicate forms of vegetation must have been chilled to death or obliged to remove farther south, and in many extensive regions, hemmed in by the advance of the sea on the one hand and land-ice on the other, they must have altogether perished. yet even in this time vegetation was not altogether extinct. along the gulf of mexico in america, and in the mediterranean basin in europe, there were still some remains of a moderate climate and certain boreal and arctic forms moving southward continued to exist here and there in somewhat high latitudes, just as similar plants now thrive in grinnell land within sight of the snows of the greenland mountains. a remarkable summary of some of these facts as they relate to england was given by an eminent english botanist, mr. carruthers, in his address as president of the biological section of the british association at birmingham in . at cromer, on the coast of norfolk, the celebrated forest-bed of newer pliocene age, and containing the remains of a copious mammalian fauna, holds also remains of plants in a state admitting of determination. these have been collected by mr. reid, of the geological survey, and were reported on by carruthers, who states that they represent a somewhat colder temperature than that of the present day. i quote the following details from the address. with reference to the plants of the forest-bed or newer pliocene he remarks as follows: "only one species (_trapa natans_, willd.) has disappeared from our islands. its fruits, which mr. reid found abundantly in one locality, agree with those of the plants found until recently in the lakes of sweden. four species (_prunus speciosa_, l., _[oe]nanthe tichenalii_, sm., _potamogeton pterophyllus_, sch., and _pinus abies_, l.) are found at present only in europe, and a fifth (_potamogeton trichoides_, cham.) extends also to north america; two species (_peucedanum palustre_, moench, and _pinus sylvestris_, l.) are found also in siberia, while six more (_sanguisorba officinalis_, l., _rubus fruticosus_, l., _cornus sanguinea_, l., _euphorbia amygdaloides_, l., _quercus robur_, l., and _potamogeton crispus_, l.) extend into western asia, and two (_fagus sylvatica_, l., and _alnus glutinosa_, l.) are included in the japanese flora. seven species, while found with the others, enter also into the mediterranean flora, extending to north africa: these are _thalictrum minus_, l., _thalictrum flavum_, l., _ranunculus repens_, l., _stellaria aquatica_, scop., _corylus avellana_, l., _yannichellia palustris_, l., and _cladium mariscus_, br. with a similar distribution in the old world, eight species (_bidens tripartita_, l., _myosotis cæspitosa_, schultz, _suæda maritima_, dum., _ceratophyllum demersum_,, l., _sparganium ramosum_, huds., _potamogeton pectinatus_, l., _carex paludosa_, good., and _osmunda regalis_, l.) are found also in north america. of the remainder, ten species (_nuphar luteum_, sm., _menyanthes trifoliata_, l., _stachys palustris_, l., _rumex maritimus_, l., _rumex acetosella_, l., _betula alba_, l., _scirpus pauciflorus_, lightf., _taxus baccata_, l., and _isoetes lacustris_, l.) extend round the north temperate zone, while three (_lycopus europæus_, l., _alisma plantago_, l., and _phragmites communis_, trim), having the same distribution in the north, are found also in australia, and one (_hippuris vulgaris_, l.) in the south of south america. the list is completed by _ranunculus aquatilis_, l., distributed over all the temperate regions of the globe, and _scirpus lacustris_, l., which is found in many tropical regions as well." he remarks that these plants, while including species now very widely scattered, present no appreciable change of characters. above this bed are glacial clays, which hold other species indicating an extremely cold climate. they are few in number, only _salix polaris_, a thoroughly arctic species, and its ally, _s. cinerea_, l., and a moss, _hypnum turgescens_, schimp., no longer found in britain, but an alpine and arctic species. this bed belongs to the beginning of the glacial period, the deposits of which have as yet afforded no plants in england. but plants occur in post-glacial and upper-glacial beds in different parts of england, to which carruthers thus refers: "the period of great cold, during which arctic ice extended far into temperate regions, was not favorable to vegetable life. but in some localities we have stratified clays with plant-remains later than the glacial epoch, yet indicating that the great cold had not then entirely disappeared. in the lacustrine beds at holderness is found a small birch (_betula nana_, l.), now limited in great britain to some of the mountains of scotland, but found in the arctic regions of the old and new world and on alpine districts in europe, and with it _prunus padus_, l., _quercus robur_, l., _corylus avellana_, l., _alnus glutinosa_, l., and _pinus sylvestris_, l. in the white clay-beds at bovey tracey of the same age there occur the leaves of _arctostaphylos uva-ursi_, l., three species of willow, viz., _salix cinerea_, l., _s. myrtilloides_, l., and _s. polaris_, wahl., and in addition to our alpine _betula nana_, l., the more familiar _b. alba_, l. two of these plants have been lost to our flora from the change of climate that has taken place, viz., _salix myrtilloides_, l., and _s. polaris_, wahl.; and _betula nana_, l., has retreated to the mountains of scotland. three others (_dryas octopetala_, l., _arctostaphylos uva-ursi_, l., and _salix herbacea_, l.) have withdrawn to the mountains of northern england, wales, and scotland, while the remainder are still found scattered over the country. notwithstanding the diverse physical conditions to which these plants have been subjected, the remains preserved in these beds present no characters by which they can be distinguished from the living representatives of the species." one of the instances referred to is very striking. at bovey tracey the arctic beds rest directly on those holding the rich, warm temperate flora of the eocene; so that here we have the evidence of fossil plants to show the change from the climate of the eocene to that of arctic lands, and the modern vegetation to indicate the return of a warm temperature. in canada, in the pleistocene beds known as the leda clays, intervening between the lower boulder clay and the saxicava sand, which also holds boulders, there are beds holding fossil plants, in some places intermixed with sea-shells and bones of marine fishes, showing that they were drifted into the sea at a time of submergence. these remains are boreal rather than arctic in character, and with the remains of drift-wood often found in the boulder deposits serve to indicate that there were at all times oases of hardy life in the glacial deserts, just as we find these in polar lands at the present day. i condense from a paper on these plants[ea] the following facts, with a few additional notes: [ea] "canadian naturalist," . the importance of all information bearing on the temperature of the post-pliocene period invests with much interest the study of the land-plants preserved in deposits of this age. unfortunately, these are few in number, and often not well preserved. in canada, though fragments of the woody parts of plants occasionally occur in the marine clays and sands, there is only one locality which has afforded any considerable quantity of remains of their more perishable parts. this is the well-known deposit of leda clay at green's creek, on the ottawa, celebrated for the perfection in which the skeletons of the capelin and other fishes are preserved in the calcareous nodules imbedded in the clay. in similar nodules, contained apparently in a layer somewhat lower than that holding the ichthyolites, remains of land-plants are somewhat abundant, and, from their association with shells of _leda glacialis_, seem to have been washed down from the land into deep water. the circumstances would seem to have been not dissimilar from those at present existing in the northeast arm of gaspé basin, where i have dredged from mud now being deposited in deep water, living specimens of _leda limatula_, mixed with remains of land-plants. the following are the species of plants recognised in these nodules: . _drosera rotundifolia_, linn. in a calcareous nodule from green's creek, the leaf only preserved. this plant is common in bogs in canada, nova scotia, and newfoundland, and thence, according to hooker, to the arctic circle. it is also european. [illustration: fig. .--_gaylussaccia resinosa_. pleistocene, canada.] . _acer spicatum_, lamx. (_acer montanum_, aiton.) leaf in a nodule from green's creek. found in nova scotia and canada, also at lake winnipeg, according to richardson. . _potentilla canadensis_, linn. in nodules from green's creek; leaves only preserved. i have had some difficulty in determining these, but believe they must be referred to the species above named, or to _p. simplex_, michx., supposed by hooker and gray to be a variety. it occurs in canada and new england, but i have no information as to its range northward. . _gaylussaccia resinosa_, torrey and gray. leaf in nodule at green's creek. abundant in new england and in canada, also on lake huron and the saskatchewan, according to richardson (fig. ). . _populus balsamifera_, linn. leaves and branches in nodules at green's creek. this is by much the most common species, and its leaves are of small size, as if from trees growing in cold and exposed situations. the species is north american and asiatic, and abounds in new england and canada. it extends to the arctic circle, and is abundant on the shores of the great slave lake and on the mckenzie river, and according to richardson constitutes much of the drift timber of the arctic coast (fig. ). [illustration: fig. .--_populus balsamifera_. pleistocene, canada.] . _thuja occidentalism_ linn. trunks and branches in the leda clay at montreal. this tree occurs in new england and canada, and extends northward into the hudson bay territories. it is a northern though not arctic species in its geographical range. according to lyell it occurs associated with the bones of mastodon in new jersey. from the great durability of its wood, it is one of the trees most likely to be preserved in aqueous deposits. . _potamogeton perfoliatus_, linn. leaves and seeds in nodules at green's creek. inhabits streams of the northern states and canada, and according to richardson extends to great slave lake. . _potamogeton pusillus._ quantities of fragments which i refer to this species occur in nodules at green's creek. they may possibly belong to a variety of _p. hybridus_ which, together with _p. natans_, now grows in the river ottawa, where it flows over the beds containing these fossils. . _cariceæ and gramineæ._ fragments in nodules from green's creek appear to belong to plants of these groups, but i cannot venture to determine their species. . _equisetum scirpoides_, michx. fragments in nodules, green's creek. this is a widely distributed species, occurring in the northern states and canada. . _fontinalis._ in nodules at green's creek there occur, somewhat plentifully, branches of a moss apparently of the genus _fontinalis_. [illustration: fig. .--frond of _fucus_. pleistocene, canada.] . _algæ._ with the plants above mentioned, both at green's creek and at montreal, there occur remains of sea-weeds (fig. ). they seem to belong to the genera _fucus_ and _ulva_, but i cannot determine the species. a thick stem in one of the nodules would seem to indicate a large _laminaria_. with the above there are found at green's creek a number of fragments of leaves, stems, and fruits, which i have not been able to refer to their species, principally on account of their defective state of preservation. none of the plants above mentioned is properly arctic in its distribution, and the assemblage may be characterised as a selection from the present canadian flora of some of the more hardy species having the most northern range. green's creek is in the central part of canada, near to the parallel of °, and an accidental selection from its present flora, though it might contain the same species found in the nodules, would certainly include with these, or instead of some of them, more southern forms. more especially the balsam poplar, though that tree occurs plentifully on the ottawa, would not be so predominant. but such an assemblage of drift-plants might be furnished by any american stream flowing in the latitude of ° to ° north. if a stream flowing to the north, it might deposit these plants in still more northern latitudes, as the mckenzie river does now. if flowing to the south, it might deposit them to the south of °. in the case of the ottawa, the plants could not have been derived from a more southern locality, nor probably from one very far to the north. we may therefore safely assume that the refrigeration indicated by these plants would place the region bordering the ottawa in nearly the same position with that of the south coast of labrador fronting on the gulf of st. lawrence at present. the absence of all the more arctic species occurring in labrador should perhaps induce us to infer a somewhat milder climate than this. the moderate amount of refrigeration thus required would in my opinion accord very well with the probable conditions of climate deducible from the circumstances in which the fossil plants in question occur. at the time when they were deposited the sea flowed up the ottawa valley to a height of to feet above its present level, and the valley of the st. lawrence was a wide arm of the sea, open to the arctic current. under these conditions the immense quantities of drift-ice from the northward, and the removal of the great heating surface now presented by the low lands of canada and new england, must have given for the ottawa coast of that period a summer temperature very similar to that at present experienced on the labrador coast, and with this conclusion the marine remains of the leda clay, as well as the few land molluscs whose shells have been found in the beds containing the plants, and which are species still occurring in canada, perfectly coincide. the climate of that portion of canada above water at the time when these plants were imbedded may safely be assumed to have been colder in summer than at present, to an extent equal to about ° of latitude, and this refrigeration may be assumed to correspond with the requirements of the actual geographical changes implied. in other words, if canada was submerged until the ottawa valley was converted into an estuary inhabited by species of _leda_, and frequented by capelin, the diminution of the summer heat consequent on such depression would be precisely suitable to the plants occurring in these deposits, without assuming any other cause of change of climate. i have arranged elsewhere the post-pliocene deposits of the central part of canada, as consisting of, in ascending order: ( ) the boulder clay; ( ) a deep-water deposit, the leda clay; and ( ) a shallow-water deposit, the saxicava sand. but, although i have placed the boulder clay in the lowest position, it must be observed that i do not regard this as a continuous layer of equal age in all places. on the contrary, though locally, as at montreal, under the leda clay, it is in other places and at other levels contemporaneous with or newer than that deposit, which itself also locally contains boulders. at green's creek the plant-bearing nodules occur in the lower part of the leda clay, which contains a few boulders, and is apparently in places overlaid by large boulders, while no distinct boulder clay underlies it. the circumstances which accumulated the thick bed of boulder clay near montreal were probably absent in the ottawa valley. in any case we must regard the deposits of green's creek as coeval with the leda clay of montreal, and with the period of the greatest abundance of _leda glacialis_, the most exclusively arctic shell of these deposits. in other words, i regard the plants above mentioned as probably belonging to the period of greatest refrigeration of which we have any evidence, of course not including that mythical period of universal incasement in ice, of which, as i have elsewhere endeavoured to show, in so far as canada is concerned, there is no evidence whatever.[eb] [eb] notes on post-pliocene of canada, "canadian naturalist," . the facts above stated in reference to post-pliocene plants concur, with all the other evidence i have been able to obtain, in the conclusion that the refrigeration of canada in the post-pliocene period consisted of a diminution of the summer heat, and was of no greater amount than that fairly attributable to the great depression of the land and the different distribution of the ice-bearing arctic current. in connection with the plants above noticed, it is interesting to observe that at green's creek, at pakenham mills, at montreal, and at clarenceville on lake champlain, species of canadian _pulmonata_ have been found in deposits of the same age with those containing the plants. the species which have been noticed belong to the genera _lymnea_ and _planorbis_. the glacial age was, fortunately, not of very long duration, though its length has been much exaggerated by certain schools of geologists,[ec] it passed away, and a returning cosmic spring gladdened the earth, and was ushered in by a time of great rainfall and consequent denudation and deposit, which has been styled the "pluvial period" the remains of the pliocene forests then returned--with somewhat diminished numbers of species--from the south and again occupied the land, though they have not been able, in their decimated condition, to restore the exuberance of the flora of the earlier tertiary. in point of fact, as we shall see in the next chapter, it is the floras originating within the polar circle and coming down from the north that are rich and copious. those that, after periods of cold or submergence, return from the south, are comparatively poor. hence the modern flora is far inferior to that of the middle kainozoic. in america, however, and in eastern asia, for reasons already stated, the return was more abundant than in europe. [ec] this i have long maintained on grounds connected with pleistocene fossils, amount of denudation and deposit, &c., and i am glad to see that prestwich, the best english authority on such subjects, has recently announced similar conclusions, based on independent reasons. simultaneously with the return of the old temperate flora, the arctic plants that had overspread the land retreated to mountain-tops, now bared of ice and snow, and back to the polar lands whence they came; and so it happens that, on the white mountains, the alps, and the himalayas, we have insular patches of the same groups of plants that exist around the pole. these changes need not have required a very long time, for the multiplication and migration of plants are very rapid, especially when aided by the agency of migratory animals. many parts of the land must, indeed, have been stocked with plants from various sources, and by agencies--as that of the sea--which might at first sight seem adverse to their distribution. the british islands, for example, have no indigenous plants. their flora consists mainly of germanic plants, which must have migrated to britain in that very late period of the post-glacial when the space now occupied by the north sea was mostly dry land. other portions of it are scandinavian plants, perhaps survivors of the glacial age, or carried by migratory birds; and still another element consists of spanish plants, brought north by spring migrants, and establishing themselves in warm and sheltered spots, just as the arctic plants do on the bleak hill-tops. the bermudas, altogether recent islands, have one hundred and fifty species of native plants, all of which are west indian and american, and must have been introduced by the sea-currents or by migratory birds. and so the earth became fitted for the residence of modern man. yet it is not so good or edenic a world as it once was, or as it may yet become, were another revolution to restore a mild climate to the arctic regions, and to send down a new swarm of migratory species to renew the face of the earth and restore it to its pristine fertility of vegetable life. thus closes this long history of the succession of plants, reaching from the far back laurentian to the present day. it has, no doubt, many breaks, and much remains to be discovered. yet it may lead us to some positive conclusions regarding the laws of the introduction of plants. one of these, and perhaps the most remarkable of all, is that certain principles were settled very far back, and have remained ever since. we have seen that in the earliest geological periods all that pertains to the structure, powers, and laws of the vegetable cell was already fixed and settled. when we consider how much this implies of mechanical structure and chemical and vital property, the profound significance of this statement becomes apparent. the relations in these respects between the living cell and the soil, the atmosphere and the sunshine, were apparently as perfect in the early palæozoic as in any subsequent time. the same may be said of the structures of the leaf and of the stem. in such old forms as nematophyton these were, it is true, peculiar and rudimentary, but in the devonian and carboniferous the structure of leaves and stems embodied all the parts and principles that we find at present. in regard to fructification there has been more progress, for, so far as we know, the highest and most complex forms of flowery, fruits, and seeds belong to the more recent periods, and simpler forms were at least dominant in the older times. yet even in this respect the great leading laws and structures of bisexual reproduction were perfected in the early palæozoic, and the improvements introduced in the gymnosperm and the angiosperm of later periods have consisted mainly in additions of accessory parts, and in modifications and refinements suited to the wants of the higher and more complex types. chapter viii. general laws of origin and migrations of plants.--relations of recent and fossil floras. the origination of the successive floras which have occupied the northern hemisphere in geological time, not, as one might at first sight suppose, in the sunny climes of the south, but under the arctic skies, is a fact long known or suspected. it is proved by the occurrence of fossil plants in greenland, in spitzbergen, and in grinnell land, under circumstances which show that these were their primal homes. the fact bristles with physical difficulties, yet is fertile of the most interesting theoretical deductions, to reach which we may well be content to wade through some intricate questions. though not at all a new fact, its full significance seems only recently to have dawned on the minds of geologists, and within the last few years it has produced a number of memoirs and addresses to learned societies, besides many less formal notices.[ed] [ed] saporta, "ancienne végétation polaire"; hooker, "presidential address to royal society," ; thistleton dyer, "lecture on plant distribution"; mr. starkie gardner, "letters in 'nature,'" , &c. the basis of most of these brochures is to be found in heer's "flora fossilis arctica." the earliest suggestion on the subject known to the writer is that of prof. asa gray, in , with reference to the probable northern source of the related floras of north america and eastern asia. with the aid of the new facts disclosed by heer and lesquereux, gray returned to the subject in , and more fully developed this conclusion with reference to the tertiary floras,[ee] and he has recently still further discussed these questions in an able lecture on "forest geography and archæology."[ef] in this he puts the case so well and tersely that we may quote the following sentences as a text for what follows: [ee] address to american association. [ef] "american journal of science," xvi., . "i can only say, at large, that the same species (of tertiary fossil plants) have been found all round the world; that the richest and most extensive finds are in greenland; that they comprise most of the sorts which i have spoken of, as american trees which once lived in europe--magnolias, sassafras, hickories, gum-trees, our identical southern cypress (for all we can see of difference), and especially _sequoias_, not only the two which obviously answer to the two big-trees now peculiar to california, but several others; that they equally comprise trees now peculiar to japan and china, three kinds of gingko-trees, for instance, one of them not evidently distinguishable from the japan species which alone survives; that we have evidence, not merely of pines and maples, poplars, birches, lindens, and whatever else characterise the temperate zone forests of our era, but also of particular species of these, so like those of our own time and country that we may fairly reckon them as the ancestors of several of ours. long genealogies always deal more or less in conjecture; but we appear to be within the limits of scientific inference when we announce that our existing temperate trees came from the north, and within the bounds of nigh probability when we claim not a few of them as the originals of present species. remains of the same plants have been found fossil in our temperate region as well as in europe." between and the writer was engaged in working out all that could be learned of the devonian plants of eastern america, the oldest known flora of any richness, and which consists almost exclusively of gigantic, and to us grotesque, representatives of the club-mosses, ferns, and mares'-tails, with some trees allied to the cycads and pines. in this pursuit nearly all the more important localities were visited, and access was had to the large collections of prof. hall and prof. newberry, in new york and ohio, and to those made in the remarkable plant-bearing beds of new brunswick by messrs. matthew and hartt. in the progress of these researches, which developed an unexpectedly rich assemblage of species, the northern origin of this old flora seemed to be established by its earlier culmination in the northeast, in connection with the growth of the american land to the southward, which took place after the great upper silurian subsidence, by elevations beginning in the north while those portions of the continent to the southwest still remained under the sea. the same result was indicated by the persistence in the carboniferous of the south and west of old erian forms, like _megalopteris_. when, in , the labours of those ten years were brought before the royal society of london, in the bakerian lecture of that year, and in a memoir illustrating no less than one hundred and twenty-five species of plants older than the great carboniferous system, these deductions were stated in connection with the conclusions of hall, logan, and dana, as to the distribution of sediment along the northeast side of the american continent, and the anticipation was hazarded that the oldest palæozoic floras would be discovered to the north of newfoundland. mention was also made of the apparent earlier and more copious birth of the devonian flora in america than in europe, a fact which is itself connected with the greater northward extension of this continent. the memoir containing these results was not published by the royal society, but its publication was secured in a less complete form in the reports of the "geological survey of canada." the part of the memoir relating to canadian fossil plants, with a portion of the theoretical deductions, was published in a report issued in .[eg] in this report the following language was used: [eg] "fossil plants of the devonian and upper silurian formations of canada," pp. , twenty plates, montreal, . "in eastern america, from the carboniferous period onward, the centre of plant distribution has been the appalachian chain. from this the plants and sediments extended westward in times of elevation, and to this they receded in times of depression. but this centre was nonexistent before the devonian period, and the centre for this must have been to the northeast, whence the great mass of older appalachian sediment was derived. in the carboniferous period there was also an eastward distribution from the appalachians, and links of connection in the atlantic bed between the floras of europe and america. in the devonian such connection can have been only far to the northeast. it is therefore in newfoundland, labrador, and greenland that we are to look for the oldest american flora, and in like manner on the border of the old scandinavian nucleus for that of europe. "again, it must have been the wide extension of the sea of the corniferous limestone that gave the last blow to the remaining flora of the lower devonian; and the re-elevation in the middle of that epoch brought in the appalachian ridges as a new centre, and established a connection with europe which introduced the upper devonian and carboniferous floras. lastly, from the comparative richness of the later erian[eh] flora in eastern america, especially in the st. john beds, it might be a fair inference that the northeastern end of the appalachian ridge was the original birthplace or centre of creation of what we may call the later palæozoic flora, or of a large part of that flora." [eh] see pages and . when my paper was written i had not seen the account published by the able swiss palæobotanist heer, of the remarkable devonian flora of bear island, near spitzbergen.[ei] from want of acquaintance with the older floras of america and western europe, heer fell into the unfortunate error of regarding the whole of bear island plants as lower carboniferous, a mistake which his great authority has tended to perpetuate, and which has even led to the still graver error of some european geologists, who do not hesitate to regard as carboniferous the fossil plants of the american deposits from the hamilton to the chemung groups inclusive, though these belong to formations underlying the oldest carboniferous, and characterised by animal remains of unquestioned devonian age. in i addressed a note to the geological society of london on the subject of the so-called "ursa stage" of heer, showing that, though it contained some forms not known at so early a date in temperate europe, it was clearly, in part at least, devonian when tested by north american standards; but that in this high latitude, in which, for reasons stated in the report above referred to, i believed the devonian plants to have originated, there might be an intermixture of the two floras. but such a mixed group should in that latitude be referred to a lower horizon than if found in temperate regions. dr. nathorst, as already stated, has recently obtained new facts which go to show that plants of two distinct horizons may have been intermixed in the collections submitted to heer. [ei] "transactions of the swedish academy" ; "journal of the london geological society," vol. xxviii. between and my attention was turned to the two sub-floras intermediate between those of the devonian and the coal-formation, the floras of the lower carboniferous (subcarboniferous of some american geologists) and the millstone grit, and in a report upon these[ej] similar deductions were expressed. it was stated that in newfoundland the coal-beds seem to belong to the millstone grit series, and as we proceed southward they belong to progressively newer portions of the carboniferous system. the same fact is observed in the coal-beds of scotland, as compared with those of england, and it indicates that the coal-formation flora, like that of the devonian, spread itself from the north, and this accords with the somewhat extensive occurrence of lower carboniferous rocks and fossils in the parry islands and elsewhere in the arctic regions. [ej] "fossil plants of lower carboniferous and millstone grit formations of canada," pp. , ten plates, montreal, . passing over the comparatively poor flora of the earlier mesozoic, consisting largely of cycads, pines, and ferns, and as yet little known in the arctic, and which may have originated in the south, though represented, according to heer, by the supposed jurassic flora of siberia, we find, especially at komé and atané in greenland, an interesting occurrence of those earliest precursors of the truly modern forms of plants which appear in the cretaceous, the period of the english chalk and of the new jersey greensands. there are two plant-groups of this age in greenland; one, that of komé, consists almost entirely of ferns, cycads, and pines, and is of decidedly mesozoic aspect. this is called lower cretaceous. the other, that of atané, holds remains of many modern temperate genera, as _populus_, _myrica_, _ficus_, _sassafras_, and _magnolia_. this is regarded as upper cretaceous. resting upon these upper cretaceous beds, without the intervention of any other formation,[ek] are beds rich in plants of much more modern appearance, and referred by heer to the miocene period, a reference, as we have seen, not warranted by comparison with the tertiary plants of europe or of america. still farther north this so-called miocene assemblage of plants appears in spitzbergen and grinnell land; but there, owing to the predominance of trees allied to the spruces, it has a decidedly more boreal character than in greenland, as might be anticipated from its nearer approach to the pole.[el] [ek] nordenskiöld, "expedition to greenland," "geological magazine," . [el] yet even here the bald cypress (_taxodium distichum_), or a tree nearly allied to it, is found, though this species is now limited to the southern states. fielden and de ranee, "journal of the geological society," . if now we turn to the cretaceous and tertiary floras of western america, as described by lesquereux, newberry, and others, we find in the lowest cretaceous rocks there known--those of the dakota group--which may be in the lower part of the middle cretaceous, a series of plants[em] essentially similar to those of the so-called upper cretaceous of greenland. they occur in beds indicating land and fresh-water conditions as prevalent at the time over great areas of the interior of america. but overlying this plant-bearing formation we have an oceanic limestone (the niobrara), corresponding in many respects to the european chalk, and extending far north into the british territory,[en] indicating that the land of the lower cretaceous was replaced by a vast mediterranean sea, filled with warm water from the equatorial currents, and not invaded by cold waters from the north. this is succeeded by thick upper cretaceous deposits of clay and sandstone, with marine remains, though very sparsely distributed; and these show that further subsidence or denudation in the north had opened a way for the arctic currents, killing out the warm-water animals of the niobrara group, and rilling up the mediterranean of that period. of the flora of these upper cretaceous periods, which must have been very long, we know something in the interior regions, from the discovery of a somewhat rich flora in the dunvegan beds of the peace river district, on the northern shore of the great cretaceous mediterranean;[eo] and on the coast of british columbia we have the remarkable cretaceous coal-field of vancouver island, which holds the remains of plants of modern genera, and, indeed, of almost as modern aspect as those of the so-called miocene of greenland. they indicate, however, a warmer climate as then prevalent on the pacific coast, and in this respect correspond with a peculiar transition flora, intermediate between the cretaceous and eocene or earliest tertiary of the interior regions, and which is described by lesquereux as the lower lignitic. [em] lesquereux, "report on cretaceous flora." [en] g. m. dawson, "report on forty-ninth parallel." [eo] "reports of dr. g. m. dawson, geological survey of canada." also, "transactions of the royal society of canada," vol. i. immediately above these upper cretaceous beds we have the great lignite tertiary of the west--the laramie group of recent american reports--abounding in fossil plants, at one time regarded as miocene, but now known to be lower eocene, though farther south extending upward toward the miocene age.[ep] these beds, with their characteristic plants, have been traced into the british territory north of the forty-ninth parallel, and it has been shown that their fossils are identical with those of the mckenzie river valley, described by heer as miocene, and probably also with those of alaska, referred to the same age.[eq] now this truly eocene flora of the temperate and northern parts of america has so many species in common with that called miocene in greenland that its identity can scarcely be doubted. these facts have led to scepticism as to the miocene age of the upper plant-bearing beds of greenland, and more especially mr. j. starkie gardner has ably argued, from comparison with the eocene flora of england and other considerations, that they are really of that earlier date.[er] [ep] lesquereux's "tertiary flora"; "white on the laramie group"; stevenson, "geological relations of lignitic groups," american philosophical society, june, ; dawson, "transactions of the royal society of canada," vol. iv.; ward, "bulletin of united states geological survey." [eq] g. m. dawson, "report on the geology of the forty-ninth parallel," where full details on these points may be found. "transactions of the royal society of canada," vol. iv. [er] "nature," december , . in looking at this question, we may fairly assume that no climate, however equable, could permit the vegetation of the neighbourhood of disco in greenland to be exactly identical with that of colorado and missouri, at a time when little difference of level existed in the two regions. either the southern flora migrated north in consequence of a greater amelioration of climate, or the northern flora moved southward as the climate became colder. the same argument, as gardner has ably shown, applies to the similarity of the tertiary plants of temperate europe to those of greenland. if greenland required a temperature of about °, as heer calculates, to maintain its eocene flora, the temperature of england and that of the southwestern states must have been higher, though probably more equable, than at present. we cannot certainly affirm anything respecting the migrations of these floras, but there are some probabilities which deserve attention. the ferns and cycads of the so-called lower cretaceous of greenland are nothing but a continuation of the previous jurassic flora. now this was established at an equally early date in the queen charlotte islands,[es] and still earlier in virginia,[et] the presumption is, therefore, that it came from the south. it has, indeed, the facies of a southern hemisphere and insular flora, and probably spread itself northward as far as greenland, at a time when our northern continents were groups of islands, and when the ocean currents were carrying warm water far toward the arctic regions. the flora which succeeds this in the sections at atané has no special affinities with the southern hemisphere, and is of a more temperate and continental character.[eu] it is not necessarily upper cretaceous, since it is similar to that of the dakota group farther south, and this is at least middle cretaceous. this flora must have originated either somewhere in temperate america or within the arctic circle, and it must have replaced the older one by virtue of increasing coolness and continental character of climate. it must, therefore, have been connected with that elevation of the land which took place at the beginning of the cretaceous. during this elevation it spread over all western america at one time or another, and, as the land again subsided under the sea of the niobrara chalk, it assumed an aspect more suited to a warm climate, but still held its place on such islands as remained above water along the pacific coast and in the north, and it continued to exist on these islands till the colder seas of the upper cretaceous had again given place to the warm plains and land-locked brackish seas or fresh-water lakes of the laramie period (eocene). thus the true upper cretaceous marks a cool period intervening between the so-called upper cretaceous (really middle cretaceous) and the so-called miocene (really lower eocene) floras of greenland. [es] "reports of the geological survey of canada." [et] fontaine has well described the mesozoic flora of virginia, "american journal of science," january, , and "report on early mesozoic floras." [eu] in the "proceedings of the royal society of tasmania," , mr. r. m. johnston, f. l. s., states that in the miocene beds of tasmania trees of european genera abound. the mesozoic flora of that island is of the usual conifero-cycadean type. ettingshausen makes a similar statement in the "geological magazine" respecting the tertiary flora of australia and new zealand, stating that, like the tertiary floras of europe, they have a mixed character, being partly of types now belonging to the northern hemisphere. this latter established itself in greenland, and probably all around the arctic circle, in the warm period of the earliest eocene, and, as the climate of the northern hemisphere became gradually reduced from that time till the end of the pliocene, it marched on over both continents to the southward, chased behind by the modern arctic flora, and eventually by the frost and snow of the glacial age. this history may admit of correction in details; but, so far as present knowledge extends, it is in the main not far from the truth. perhaps the first great question which it raises is that as to the causes of the alternations of warm and cold climates in the north, apparently demanded by the vicissitudes of the vegetable kingdom. here we may set aside the idea that in former times plants were suited to endure greater cold than at present. it is true that some of the fossil greenland plants are of unknown genera, and many are species new to us; but we are on the whole safe in affirming that they must have required conditions similar to those necessary to their modern representatives, except within such limits as we now find to hold in similar cases among existing plants. still we know that at the present time many species found in the equable climate of england will not live in canada, though species to all appearance similar in structure are native here. there is also some reason to suppose that species when new may have greater hardiness and adaptability than when in old age and verging toward extinction. in any case these facts can account for but a small part of the phenomena, which require to be explained by physical changes affecting the earth as a whole, or at least the northern hemisphere. many theoretical views have been suggested on this subject, and perhaps the most practical way of disposing of these will be first to set aside a number which are either precluded by the known facts, incapable of producing the effects, or altogether uncertain as to their possible occurrence. . in this class we may place the theory that the poles of the earth have changed their position. independently of astronomical objections, there is good geological evidence that the poles of the earth must have been nearly in their present places from the dawn of life until now. from the laurentian upward, those organic limestones which mark the areas where warm and shallow equatorial water was spreading over submerged continents are so disposed as to prove the permanence of the poles. in like manner all the great foldings of the crust of the earth have followed lines which are parts of great circles tangent to the existing polar circles. so, also, from the cambrian age the great drift of sediment from the north has followed the line of the existing arctic currents from the northeast to the southwest, throwing itself, for example, along the line of the appalachian uplifts in eastern america, and against the ridge of the cordilleras in the west. . some of the above considerations, along with astronomical evidence, prevent us from assuming any considerable change in the obliquity of the axis of the earth during geological time. . that the earth and the sun have diminished in heat during geological time seems probable; but physical and geological facts alike render it certain that this influence could have produced no appreciable effect, even in the times of the earliest floras, and certainly not in the case of tertiary vegetation. . it has been supposed that the earth may have at different times traversed more or less heated zones of space, giving alternations of warm and cold temperature. no such differences in space are, however, known, nor does there seem any good ground for imagining their existence. . the heat of the sun is known to be variable, and the eleven years' period of sun-spots has recently attracted much attention as producing appreciable effects on the seasons. there may possibly be longer cycles of solar energy, or the sun may be liable, like some variable stars, to paroxysms of increased energy. such changes are possible, and may fairly be taken into the account, provided that we fail to find known causes sufficient to account for the phenomena. of well-known causes there seem to be but three. these are: first, that urged by lyell--viz., the varying distribution of land and water along with that of marine currents; secondly, the varying eccentricity of the earth's orbit, along with the precession of the equinoxes, and the effects of this on oceanic circulation, as illustrated by croll; thirdly, the different conditions of the earth's atmosphere with reference to radiation, as argued by tyndall and hunt. as these causes are all founded on known facts, and not exclusive of each other, we may consider them together. i shall take the lyellian theory first, regarding it as the most important, and the best supported by geological facts. we know that the present distribution of land and water greatly influences climate, more especially by affecting that of the ocean currents and of the winds, and by the different action of land as compared with water in the reception and radiation of heat. the present distribution of land gives a large predominance to the arctic and sub-arctic regions, as compared with the equatorial and with the antarctic; and we might readily imagine other distributions that would give very different results. but this is not an imaginary case. we know that, while the forms and positions of the great continents have been fixed from a very early date, they have experienced many great submergences and re-elevations, and that these have occurred in somewhat regular sequence, as evidenced by the cyclical alternations of organic limestones and earthy sediments in successive geological formations. an example bearing on our present subject may serve to illustrate this. in the latter part of the upper silurian period (the lower helderberg age), vast areas of the american continent[ev] were covered with an ocean in which were deposited organic limestones whose fossils show that this great interior sea was pervaded by equatorial waters bringing food and warmth, while the incipient ranges of the appalachians on the east, and the cordilleras on the west, and the laurentian axis on the north, fenced off from it the colder arctic waters. how different must the climate of america and of the region north of it have been in these circumstances from that which prevails at present, or from that which prevailed in certain other periods, when it was open to the incursions of the arctic ice-laden currents, bearing loads of fine sediment![ew] it was in these circumstances, and in the similar circumstances in which the great corniferous limestone of the devonian was deposited--a limestone showing in its rich coral fauna even warmer waters than those of the lower helderberg--that the devonian flora took its origin in the north and advanced southward over new lands in process of emergence from the sea. the somewhat similar condition evidenced by the lower carboniferous limestone preceded the advent of the great and rich flora of the coal-formation. [ev] see a memoir and map by prof. hall, "reports of the regents of new york," -' . [ew] it seems certain that the faunæ of the old limestones, like the trenton, niagara, lower helderberg, and corniferous, belong to warm and sheltered sea areas, and that those rich in graptolites and trilobites, enclosed in muddy sediments, belong to the colder arctic waters. such arctic faunæ are those of the quebec group and of the utica shale, and to some extent that of the hamilton group. lyell's theory on this subject has, i think, in some recent publications, been somewhat misapprehended. it is true that he stated hypothetically two contrasted conditions of distribution, in one of which all the land was equatorial, in another all polar; but he did not suppose that these conditions had actually occurred; and even in his earlier editions, before the recent discoveries and discussions as to ocean currents, he was always careful to attach due value to these in connection with subsidences and elevations.[ex] in his later editions he introduced more full references to current action, and also stated croll's theory, but still maintained the validity of his original conclusions. [ex] see "principles of geology," edition of , chapter vii. the sufficiency of this lyellian theory to account for the facts, in so far as plants are concerned, may, i think, be inferred from the course of the isothermal lines at present. the south end of greenland is on the latitude of christiania in norway on the one hand, and of fort liard in the peace river region on the other; and while greenland is clad in ice and snow, wheat and other grains, and the ordinary trees of temperate climates, grow at the latter places,[ey] it is evident, therefore, that only exceptionally unfavourable circumstances prevent the greenland area from still possessing a temperate flora, and these unfavourable circumstances possibly tell even on the localities with which we have compared it. further, the mouth of the mckenzie river is in the same latitude with disco, near which are some of the most celebrated localities of fossil cretaceous and tertiary plants. yet the mouth of the mckenzie river enjoys a much more favourable climate and has a much more abundant flora than disco. if north greenland were submerged, and low land reaching to the south terminated at disco, and if from any cause either the cold currents of baffin's bay were arrested, or additional warm water thrown into the north atlantic by the gulf stream, there is nothing to prevent a mean temperature of ° fahr. from prevailing at disco; and the estimate ordinarily formed of the requirements of its extinct floras is °,[ez] which is probably above rather than below the actual temperature required. [ey] see "macoun's report," "geological survey of canada," and richardson's "boat voyage." [ez] heer. see, also, papers by prof. haughton and by gardner in "nature" for . since, then, geological facts assure us of mutations of the continents much greater than those apparently required to account for the changes of climate implied in the existence of the ancient arctic floras, it does not seem absolutely necessary to invoke any others.[fa] if, however, there are other true causes which might either aid or counteract those above referred to, it may be well to consider them. [fa] sir william thomson, "transactions of the geological society of glasgow," february , . mr. croll has, in his valuable work "climate and time" and in various memoirs, brought forward an ingenious astronomical theory to account for changes of climate. this theory, as stated by himself in a recent paper,[fb] is that when the eccentricity of the earth's orbit is at a high value, and the northern winter solstice is in perihelion, agencies are brought into operation which make the southeast trade-winds stronger than the northeast, and compel them to blow over upon the northern hemisphere as far as the tropic of cancer. the result is that all the great equatorial currents of the ocean are impelled into the northern hemisphere, which thus, in consequence of the immense accumulation of warm water, has its temperature raised, so that ice and snow must to a great extent disappear from the arctic regions. in the prevalence of the converse conditions, the arctic zone becomes clad in ice, and the southern has its temperature raised. [fb] "cataclysmic theories of geological climate," "geological magazine," may, . at the same time, according to croll's calculations, the accumulation of ice on either pole would tend, by shifting the earth's centre of gravity, to raise the level of the ocean and submerge the land on the colder hemisphere. thus a submergence of land would coincide with a cold condition, and emergence with increasing warmth. facts already referred to, however, show that this has not always been the case, but that in many cases submergence was accompanied with the influx of warm equatorial waters and a raised temperature, this apparently depending on the question of local distribution of land and water; and this in its turn being regulated not always by mere shifting of the centre of gravity, but by foldings occasioned by contraction, by equatorial subsidences resulting from the retardation of the earth's rotation, and by the excess of material abstracted by ice and frost from the arctic regions, and drifted southward along the lines of arctic currents. this drifting must in all geological times have greatly exceeded, as it certainly does at present, the denudation caused by atmospheric action at the equator, and must have tended to increase the disposition to equatorial collapse occasioned by retardation of rotation.[fc] [fc] croll, in "climate and time," and in a note read before the british association in , takes an opposite view; but this is clearly contrary to the facts of sedimentation, which show a steady movement of _débris_ toward the south and southwest. while such considerations as those above referred to tend to reduce the practical importance of mr. croll's theory., on the other hand they tend to remove one of the greatest objections against it--namely, that founded on the necessity of supposing that glacial periods recur with astronomical regularity in geological time. they cannot do so if dependent on other causes inherent in the earth itself, and producing important movements of its crust. the third great cause of warmer climates in the past is the larger proportion of carbon dioxide, or carbonic-acid gas, in the atmosphere in early geological times, as proved by the immense amount of carbon now sealed up in limestone and coal, and which must at one time have been in the air. it has been shown that a very small additional quantity of this substance would so obstruct radiation of heat from the earth as to act almost like a glass roof. if, however, the quantity of carbonic acid, great at first, was slowly and regularly removed, even if, as suggested by hunt, small additional supplies were gradually added from space, this cause could have affected only the very oldest floras. but it is known that some comets and meteorites contain carbonaceous matter, and this allows us to suppose that accessions of carbon may have been communicated at irregular intervals. if so, there may have been cycles of greater and less abundance of this substance, and an atmosphere rich in carbon dioxide might at one and the same time afford warmth and abundance of food to plants. it thus appears that the causes of ancient vicissitudes of climate are somewhat complex, and when two or more of them happened to coincide very extreme changes might result, having most important bearings on the distribution of plants. this may help us to deal with the peculiarities of the great glacial age, which may have been rendered exceptionally severe by the combination of several of the causes of refrigeration. we must not suppose, however, that the views of those extreme glacialists who suppose continental ice-caps reaching half way to the equator are borne out by facts. in truth, the ice accumulating round the pole must have been surrounded by water, and there must have been tree-clad islands in the midst of the icy seas, even in the time of greatest refrigeration. this is proved by the fact that, in the leda clay of eastern canada, which belongs to the time of greatest submergence, and whose fossil shells show sea-water almost at the freezing-point, there are leaves of poplars and other plants which must have been drifted from neighbouring shores. similar remains occur in clays of like origin in the basin of the great lakes and in the west. these have been called "interglacial," but there is no evidence to prove that they are not truly glacial. thus, while we need not suppose that plants existed within the arctic circle in the glacial age, we have evidence that those of the cold temperate and sub-arctic zones continued to exist pretty far north. at the same time the warm temperate flora would be driven to the south, except where sustained in insular spots warmed by the equatorial currents. it would return northward on the re-elevation of the land and the renewal of warmth. if, however, our modern flora is thus one that has returned from the south, this would account for its poverty in species as compared with those of the early tertiary. groups of plants descending from the north have been rich and varied. returning from the south they are like the shattered remains of a beaten army. this, at least, has been the case with such retreating floras as those of the lower carboniferous, the permian, and the jurassic, and possibly that of the lower eocene of europe. the question of the supply of light to an arctic flora is much less difficult than some have imagined. the long summer day is in this respect a good substitute for a longer season of growth, while a copious covering of winter snow not only protects evergreen plants from those sudden alternations of temperature which are more destructive than intense frost, and prevents the frost from penetrating to their roots, but, by the ammonia which it absorbs, preserves their greenness. according to dr. brown, the danish ladies of disco long ago solved this problem.[fd] he informs us that they cultivate in their houses most of our garden flowers--as roses, fuchsias, and geraniums--showing that it is merely warmth and not light that is required to enable a sub-tropical flora to thrive in greenland. even in canada, which has a flora richer in some respects than that of temperate europe, growth is effectually arrested by cold for nearly six months, and though there is ample sunlight there is no vegetation. it is, indeed, not impossible that in the plans of the creator the continuous summer sun of the arctic regions may have been made the means for the introduction, or at least for the rapid growth and multiplication, of new and more varied types of plants. [fd] "florula discoana," botanical society of edinburgh, . much, of course, remains to be known of the history of the old floras, whose fortunes i have endeavoured to sketch, and which seem to have been driven like shuttle-cocks from north to south, and from south to north, especially on the american continent, whose meridional extension seems to have given a field specially suited for such operations. this great stretch of the western continent, from north to south, is also connected with the interesting fact that, when new floras are entering from the arctic regions, they appear earlier in america than in europe, and that in times when old floras are retreating from the south old genera and species linger longer in america. thus, in the devonian and cretaceous new forms of those periods appear in america long before they are recognized in europe, and in the modern epoch forms that would be regarded in europe as miocene still exist. much confusion in reasoning as to the geological ages of the fossil floras has arisen from want of attention to this circumstance. what we have learned respecting this wonderful history has served strangely to change some of our preconceived ideas. we must now be prepared to admit that an eden can be planted even in spitzbergen, that there are possibilities in this old earth of ours which its present condition does not reveal to us; that the present state of the world is by no means the best possible in relation to climate and vegetation; that there have been and might be again conditions which could convert the ice-clad arctic regions into blooming paradises, and which at the same time would moderate the fervent heat of the tropics. we are accustomed to say that nothing is impossible with god; but how little have we known of the gigantic possibilities which lie hidden under some of the most common of his natural laws! these facts have naturally been made the occasion of speculations as to the spontaneous development of plants by processes of varietal derivation. it would, from this point of view, be a nice question to calculate how many revolutions of climate would suffice to evolve the first land-plant; what are the chances that such plant would be so dealt with by physical changes as to be preserved and nursed into a meagre flora like that of the upper silurian or the jurassic; how many transportations to greenland would suffice to promote such meagre flora into the rich and abundant forests of the upper cretaceous, and to people the earth with the exuberant vegetation of the early tertiary. such problems we may never be able to solve. probably they admit of no solution, unless we invoke the action of an almighty mind, operating through long ages, and correlating with boundless power and wisdom all the energies inherent in inorganic and organic nature. even then we shall perhaps be able to comprehend only the means by which, after specific types have been created, they may, by the culture of their maker, be "sported" into new varieties or subspecies, and thus fitted to exist under different conditions or to occupy higher places in the economy of nature. before venturing on such extreme speculations as some now current on questions of this kind, we would require to know the successive extinct floras as perfectly as those of the modern world, and to be able to ascertain to what extent each species can change either spontaneously or under the influence of struggle for existence or expansion under favourable conditions, and under arctic semi-annual days and nights, or the shorter days of the tropics. such knowledge, if ever acquired, it may take ages of investigation to accumulate. as to the origin and mode of introduction of successive floras, i am, for the reasons above stated, not disposed to dogmatise, or to adopt as final any existing theory of the development of the vegetable kingdom. still, some laws regulating the progress of vegetable life may be recognised, and i propose to state these in connection with the palæozoic floras, to which my own studies have chiefly related. fossil plants are almost proverbially uncertain with reference to their accurate determination, and have been regarded as of comparatively little utility in the decision of general questions of palæontology. this results principally from the fragmentary condition in which they have been studied, and from the fact that fragments of animal structures are more definite and instructive than corresponding portions of plants. it is to be observed, however, that our knowledge of fossil plants becomes accurate in proportion to the extent to which we can carry the study of specimens in the beds in which they are preserved, so as to examine more perfect examples than those usually to be found in museums. when structures are taken into the account, as well as external forms, we can also depend more confidently on our results. further, the abundance of specimens to be obtained in particular beds often goes far to make up for their individual imperfection. the writer of these pages has been enabled to avail himself very fully of these advantages; and on this account, if on no other, feels entitled to speak with some authority on theoretical questions. it is an additional encouragement to pursue the subject, that, when we can obtain definite information as to the successive floras of any region, we thereby learn much as to climate and vicissitudes in regard to the extent of land and water; and that, with reference to such points, the evidence of fossil plants, when properly studied, is, from the close relation of plants to those stations and climates, even more valuable than that of animal fossils. it is necessary, however, that in pursuing such inquiries we should have some definite views as to the nature and permanence of specific forms, whether with reference to a single geological period or to successive periods; and i may be excused for stating here some general principles, which i think important for our guidance. . botanists proceed on the assumption, vindicated by experience, that, within the period of human observation, species have not materially varied or passed into each other. we may make, for practical purposes, the same assumption with regard to any given geological period, and may hold that for each such period there are specific types which, for the time at least, are invariable. . when we inquire what constitutes a good species for any given period, we have reason to believe that many names in our lists represent merely varietal forms or erroneous determinations. this is the case even in the modern flora; and in fossil floras, through the poverty of specimens, their fragmentary condition, and various states of preservation, it is still more likely to occur. every revision of any group of fossils detects numerous synonyms, and of these many are incapable of detection without the comparison of large suites of specimens. . we may select from the flora of any geological period certain forms, which i shall call _specific types_, which may for such period be regarded as unchanging. having settled such types, we may compare them with similar forms in other periods, and such comparisons will not be vitiated by the uncertainty which arises from the comparison of so-called species which may, in many cases, be mere varietal forms, as distinguished from specific types. our types may be founded on mere fragments, provided that these are of such a nature as to prove that they belong to distinct forms which cannot pass into each other, at least within the limits of one geological period. . when we compare the specific types of one period with those of another immediately precedent or subsequent, we shall find that some continue unchanged through long intervals of geological time, that others are represented by allied forms regarded either as varietal or specific, and as derived or otherwise, according to the view which we may entertain as to the permanence of species. on the other hand, we also find new types not rationally deducible on any theory of derivation from those known in other periods. further, in comparing the types of a poor period with those of one rich in species, we may account for the appearance of new types in the latter by the deficiency of information as to the former; where many new types appear in the poorer period this conclusion seems less probable. for example, new types appearing in poor formations, like the lower erian and lower carboniferous, have greater significance than if they appeared in the middle erian or in the coal measures. . when specific types disappear without any known successors, under circumstances in which it seems unlikely that we should have failed to discover their continuance, we may fairly assume that they have become extinct, at least locally; and where the field of observation is very extensive, as in the great coal-fields of europe and america, we may esteem such extinction as practically general, at least for the northern hemisphere. when many specific types become extinct together, or in close succession, we may suppose that such extinction resulted from physical changes; but where single types disappear, under circumstances in which others of similar habit continue, we may not unreasonably conjecture that, as pictet has argued in the case of animals, such types may have been in their own nature limited in duration, and may have died out without any external cause. . with regard to the _introduction_ of specific types we have not as yet a sufficient amount of information. even if we freely admit that ordinary specific forms, as well as mere varieties, may result from derivation, this by no means excludes the idea of primitive specific types originating in some other way. just as the chemist, after analysing all compounds and ascertaining all allotropic forms, arrives at length at certain elements not mutually transmutable or derivable, so the botanist and zoölogist must expect sooner or later to arrive at elementary specific types, which, if to be accounted for at all, must be explained on some principle distinct from that of derivation. the position of many modern biologists, in presence of this question, may be logically the same with that of the ancient alchemists with reference to the chemical elements, though the fallacy in the case of fossils may be of more difficult detection. our business at present, in the prosecution of palæobotany, is to discover, if possible, what are elementary or original types, and, having found these, to enquire as to the law of their creation. . in prosecuting such questions geographical relations must be carefully considered. when the floras of two successive periods have existed in the same region, and under circumstances that render it probable that plants have continued to grow on the same or adjoining areas throughout these periods, the comparison becomes direct, and this is the case with the erian and carboniferous floras in northeastern america. but, when the areas of the two formations are widely separated in space as well as in time, any resemblances of facies that we may observe may have no connection whatever with an unbroken continuity of specific types. i desire, however, under this head, to affirm my conviction that, with reference to the erian and carboniferous floras of north america and of europe, the doctrine of "homotaxis," as distinct from actual contemporaneity, has no place. the succession of formations in the palæozoic period evidences a similar series of physical phenomena on the grandest scale throughout the northern hemisphere. the succession of marine animals implies the continuity of the sea-bottoms on which they lived. the headquarters of the erian flora in america and europe must have been in connected or adjoining areas in the north atlantic. the similarity of the carboniferous flora on the two sides of the atlantic, and the great number of identical species, proves a still closer connection in that period. these coincidences are too extensive and too frequently repeated to be the result of any accident of similar sequence at different times, and this more especially as they extend to the more minute differences in the features of each period, as, for instance, the floras of the lower and upper devonian, and of the lower, middle, and upper carboniferous. . another geographical question is that which relates to centres of dispersion. in times of slow subsidence of extensive areas, the plants inhabiting such areas must be narrowed in their range and often separated from one another in detached spots, while, at the same time, important climatal changes must also occur. on the re-emergence of the land such of these species as remained would again extend themselves over their former areas of distribution, in so far as the new climatal and other conditions would permit. we would naturally suppose that the first of the above processes would tend to the elimination of varieties, the second, to their increase; but, on the other i hand, the breaking up of a continental flora into that of distinct islets, and the crowding together of many forms, might be a process fertile in the production of some varieties if fatal to others. further, it is possible that these changes of subsidence may have some connection with the introduction, as well as with the extinction, even of specific types. it is certain, at least, in the case of land-plants, that such types come in most plentifully immediately after elevation, though they are most abundantly preserved in periods of slow subsidence. i do not mean, however, that this connection is one of cause and effect; there are, indeed, indications that it is not so. one of these is, that in some cases the enlargement of the area of the land seems to be as injurious to terrestrial species as its diminution. . another point on which i have already insisted, and which has been found to apply to the tertiary as well as to the palæozoic floras, is the appearance of new types within the arctic and boreal areas, and their migration southward. periods in which the existence of northern land coincided with a general warm temperature of the northern hemisphere seem to have been those most favourable to the introduction of new forms of land-plants. hence, there has been throughout geological time a general movement of new floras from the palæarctic and nearctic regions to the southward. applying the above considerations to the erian and carboniferous floras of north america, we obtain some data which may guide us in arriving at general conclusions. the erian flora is comparatively poor, and its types are in the main similar to those of the carboniferous. of these types a few only reappear in the middle coal-formation under identical forms; a great number appear under allied forms; some altogether disappear. the erian flora of new brunswick and maine occurs side by side with the carboniferous of the same region; so does the erian of new york and pennsylvania with the carboniferous of those states. thus we have data for the comparison of successive floras in the same region. in the canadian region we have, indeed, in direct sequence, the floras of the upper silurian, the lower, middle, and upper erian, and the lower, middle, and upper carboniferous, all more or less distinct from each other, and affording an admirable series for comparison in a region whose geographical features are very broadly marked. all these floras are composed in great part of similar types, and probably do not indicate very dissimilar general physical conditions, but they are separated from each other by the great subsidences of the corniferous limestone and the lower carboniferous limestone, and by the local but intense subterranean action which has altered and disturbed the erian beds toward the close of that period. still, these changes were not universal. the corniferous limestone is absent in gaspé, and probably in new brunswick, where, consequently, the erian flora could continue undisturbed during that long period. the carboniferous limestone is absent from the slopes of the appalachians in pennsylvania, where a retreat may have been afforded to the upper erian and lower carboniferous floras. the disturbances at the close of the erian were limited to those eastern regions where the great limestone-producing subsidences were unfelt, and, on the other hand, are absent in ohio, where the subsidences and marine conditions were almost at a maximum. bearing in mind these peculiarities of the area in question, we may now group in a tabular form the distinct specific types recognised in the erian system, indicating, at the same time, those which are represented by identical species in the carboniferous, those represented by similar species of the same general type, and those not represented at all. for example, _calamites cannæformis_ extends as a species into the carboniferous; _asterophyllites latifolia_ does not so extend, but is represented by closely allied species of the same type; _nematophyton_ disappears altogether before we reach the carboniferous. _table of erian and carboniferous specific types._ erian types. represented in by identical by related carboniferous-- types. forms. . syringoxylon mirabile ? . nematoxylon . nematophyton . aporoxylon . ormoxylon . dadoxylon * . sigillaria vanuxemii * . s. palpebra * . didymophyllum . calamodendron * . calamites transitionis * . c. cannæformis * . asterophyllites scutigera * . a. latifolia . annularia laxa . sphenophyllum antiquum * . cyclostigma . arthrostigma . lepidodendron gaspianum * . l. corrugatum * . lycopodites matthewi * . l. richardsoni . ptilophyton vanuxemii . lepidophloios antiquus * . psilophyton princeps . p. robustius . cordaites robbii * . c. angustifolia . archæopteris jacksoni . aneimites obtusa * . platyphyllum brownii . cyclopteris varia * . c. obtusa . neuropteris polymorpha * . n. serrulata * . n. retorquata * . n. resecta . megalopteris dawsoni. . sphenopteris hoeninghausi * . s. harttii * . hymenophyllites curtilobus . h. obtusilobus * . alethopteris discrepans * . pecopteris serrulata * . p. preciosa . trichomanites * . callipteris * . cardiocarpum * . c. crampii . antholithes * . trigonocarpum * of the above forms, fifty-one in all, found in the erian of eastern america, all, except the last four, are certainly distinct specific types. of these only four reappear in the carboniferous under identical species, but no less than twenty-six reappear under representative or allied forms, some at least of which a derivationist might claim as modified descendants. on the other hand, nearly one half of the devonian types are unknown in the carboniferous, while there remain a very large number of carboniferous types not accounted for by anything known in the devonian. further, a very poor flora, including only two or three types, is the predecessor of the erian flora in the upper silurian, and the flora again becomes poor in the upper devonian and lower carboniferous. every new species discovered must more or less modify the above statements, and the whole erian flora of america, as well as the carboniferous, requires a thorough comparison with that of europe before general conclusions can be safely drawn. in the mean time i may indicate the direction in which the facts seem to point by the following general statements: . some of the forms reckoned as specific in the devonian and carboniferous may be really derivative races. there are indications that such races may have originated in one or more of the following ways: ( ) by a natural tendency in synthetic types to become specialised in the direction of one or other of their constituent elements. in this way such plants as _arthrostigma_ and _psilophyton_ may have assumed new varietal forms. ( ) by embryonic retardation or acceleration,[fe] whereby certain species may have had their maturity advanced or postponed, thus giving them various grades of perfection in reproduction and complexity of structure. the fact that so many erian and carboniferous plants seem to be on the confines of the groups of acrogens and gymnosperms may be supposed favourable to such exchanges. ( ) the contraction and breaking up of floras, as occurred in the middle erian and lower carboniferous, may have been eminently favourable to the production of such varietal forms as would result from what has been called the "struggle for existence." ( ) the elevation of a great expanse of new land at the close of the middle erian and the beginning of the coal period would, by permitting the extension of species over wide areas and fertile soils, and by removing the pressure previously existing, be eminently favourable to the production of new, and especially of improved, varieties. [fe] in the manner illustrated by hyatt and cope. . whatever importance we may attach to the above supposed causes of change, we still require to account for the origin of our specific types. this may forever elude our observation, but we may at least hope to ascertain the external conditions favourable to their production. in order to attain even to this it will be necessary to inquire critically, with reference to every acknowledged species, what its claims to distinctness are, so that we may be enabled to distinguish specific types from mere varieties. having attained to some certainty in this, we may be prepared to inquire whether the conditions favourable to the appearance of new varieties were also those favourable to the creation of new types, or the reverse--whether these conditions were those of compression or expansion, or to what extent the appearance of new types may be independent of any external conditions, other than those absolutely necessary for their existence. i am not without hope that the further study of fossil plants may enable us thus to approach to a comprehension of the laws of the creation, as distinguished from those of the continued existence of species. . in the present state of our knowledge we have no good ground either to limit the number of specific types beyond what a fair study of our material may warrant, or to infer that such primitive types must necessarily have been of low grade, or that progress in varietal forms has always been upward. the occurrence of such an advanced and specialised type as that of _dadoxylon_ in the middle devonian should guard us against these errors. the creative process may have been applicable to the highest as well as to the lowest forms, and subsequent deviations must have included degradation as well as elevation. i can conceive nothing more unreasonable than the statement sometimes made that it is illogical or even absurd to suppose that highly organised beings could have been produced except by derivation from previously existing organisms. this is begging the whole question at issue, depriving science of a noble department of inquiry on which it has as yet barely entered, and anticipating by unwarranted assertions conclusions which may perhaps suddenly dawn upon us through the inspiration of some great intellect, or may for generations to come baffle the united exertions of all the earnest promoters of natural science. our present attitude should not be that of dogmatists, but that of patient workers content to labour for a harvest of grand generalisations which may not come till we have passed away, but which, if we are earnest and true to nature and its creator, may reward even some of us. within the human period great changes of distribution of plants have occurred, chiefly through the agency of man himself, and we have had ample evidence that plants are able to establish themselves and prosper in climates and conditions to which unaided they could not have transported themselves, as, for instance, in the case of european weeds naturalised in australia and new zealand. there is, however, no reason to believe that any specific change has occurred to any plant within the pleistocene or modern period. in a recent address, delivered to the biological section of the british association, mr. carruthers has discussed this question, and has shown that the earliest vegetable specimens described by dr. schweinfurth from the egyptian tombs present no appearance of change. this fact appears also in the leaves and other organs of plants preserved in the nodules in the pleistocene clays of the ottawa, and in specimens of similar age found in various places in britain and the continent of europe.[ff] [ff] "proceedings british association," , "pleistocene plants of canada," canadian naturalist, . the difficulties attending the ordinary theories of evolution as applied to plants have been well set forth by the same able botanist in his "presidential address to the geological association in ," a paper which deserves careful study. one of his illustrations is that ancient willow, _salix polaris_, referred to in a previous chapter, which now lives in the arctic regions, and is found fossil in the pleistocene beds at cromer and at bovey tracey. he notes the fact that the genus _salix_ is a very variable one, including subgeneric groups and species, with no less than varieties and hybrids. _salix polaris_ belongs to a subgeneric group containing species, which are arranged in four sections, that to which _s. polaris_ belongs containing six species. now it is easy to construct a theoretical phylogeny of the derivation of the willows from a supposed ancestral source, but when we take our little _s. polaris_ we find that this one twig of our ancestral tree takes us back without change to the glacial period. the six species would take us still farther, and the sections, sub-genera, and genus at the same rate would require an incalculable amount of past time. he concludes the inquiry in the following terms: "but when we have reached the branch representing the generic form we have made but little progress in the phylogenesis of _salix_. with _populus_ this genus forms a small order, salicineæ, the two genera are closely allied, yet separated by well-marked characters; it is not, however, difficult to conceive of both having sprung from a generalised form. but there is no record of such a form. the two genera appear together among the earliest known dicotyledons, the willows being represented by six and the poplars by nine species. the ordinal form, if it ever existed, must necessarily be much older than the period of the upper cretaceous rocks, that is, than the period to which the earliest known dicotyledons belong. "the salicineæ are related to five other natural orders, in all of which the apetalous flowers are arranged in catkins. these different though allied orders must be led up by small modifications to a generalised amentiferous type, and thereafter the various groups of apetalous plants by innumerable eliminations of differentiating characters until the primitive form of the apetalous plant is reached. beyond this the uncurbed imagination will have more active work in bridging over the gap between angiosperms and gymnosperms, in finding the intermediate forms that led up to the vascular cryptogams, and on through the cellular plants to the primordial germ. every step in this phylogenetic tree must be imagined. the earliest dicotyledon takes us not a step farther back in the phylogenetic history of _salix_ than that supplied by existing vegetation. all beyond the testimony of our living willows is pure imagination, unsupported by a single fact. so that here, also, the evidence is against evolution, and there is none in favour of it." it is easy to see that similar difficulties beset every attempt to trace the development of plants on the principle of slow and gradual evolution, and we are driven back on the theory of periods of rapid origin, as we have already seen suggested by saporta in the case of the cretaceous dicotyledons. such abrupt and plentiful introduction of species over large areas at the same time, by whatever cause effected--and we are at present quite ignorant of any secondary causes--becomes in effect something not unlike the old and familiar idea of creation. science must indeed always be baffled by questions of ultimate origin, and, however far it may be able to trace the chain of secondary causation and development, must at length find itself in the presence of the great creative mind, who is "before all things and in whom all things consist." appendix. i.--comparative view of the successive palÆozoic floras of northeastern america and great britain. in eastern canada there is a very complete series of fossil plants, extending from the silurian to the permian, and intermediate in its species between the floras of interior america and of europe. i may use this succession, mainly worked out by myself,[fg] to summarise the various palæozoic floras and sub-floras, in order to give a condensed view of this portion of the history of the vegetable kingdom, and to direct attention to the important fact, too often overlooked, that there is a definite succession of fossil plants as well as of animals, and that this is important as a means of determining geological horizons. a british list for comparison has been kindly prepared for me by mr. r. kidston, f. gr. s. for lists referring to the western and southern portions of america, i may refer to the reports of lesquereux and fontaine and white.[fh] [fg] "acadian geology," "reports on fossil plants of canada," geological survey of canada. [fh] "geological surveys of pennsylvania, ohio, and illinois." in this connection i am reminded, by an excellent little paper of m. zeiller,[fi] on carboniferous plants from the region of the zambesi, in africa, that the flora which in the carboniferous period extended over the temperate portions of the northern hemisphere and far into the arctic, also passed across the equator and prevailed in the southern hemisphere. of eleven species brought from the zambesi by m. lapierre and examined by m. zeiller, all were identical with european species of the upper coal-formation, and the same fact has been observed in the coal flora of the cape colony.[fj] these facts bear testimony to the remarkable uniformity of climate and vegetation in the coal period, and i perfectly agree with zeiller that they show, when taken in connection with other parallelisms in fossils, an actual contemporaneousness of the coal flora over the whole world. [fi] paris, . [fj] grey, "journal of the geological society," vol. xxvii. . carboniferous flora. ( ) _permo-carboniferous sub-flora_: this occurs in the upper member of the carboniferous system of nova scotia and prince edward island, originally named by the writer the newer coal-formation, and more recently the permo-carboniferous, and the upper beds of which may not improbably be contemporaneous with the lower permian or lower dyas of europe. in this formation there is a predominance of red sandstones and shales, and it contains no productive beds of coal. its fossil plants are for the most part of species found in the middle or productive coal-formation, but are less numerous, and there are a few new forms akin to those of the european permian. the most characteristic species of the upper portion of the formation, which has the most decidedly permian aspect, are the following: _dadoxylon materiarium_, dawson. * _walchia_ (_araucarites_) _robusta_, dn. * _w._ (_a._) _gracilis_, dn. * _w. imbricatula_, dn. _calamites suckovii_, brongt. _c. cistii_, brongt. * _c. gigas_, brongt. _neuropteris rarinervis_, bunbury. _alethopteris nervosa_, brongt. _pecopteris arborescens_, brongt. * _p. rigida_, dn. _p. oreopteroides_, brongt. * _cordaites simplex_, dn. of these species, those marked with an asterisk have not yet been found in the middle or lower members of the carboniferous system. they will be found described, and several of them figured, in my "report on the geology of prince edward island."[fk] the others are common and widely diffused carboniferous species, some of which have extended to the permian period in europe as well. from the upper beds, characterised by these and a few other species, there is a gradual passage downward into the productive coal-measures, and a gradually increasing number of true coal-formation species. [fk] . it is worthy of remark here that the association in the permo-carboniferous of numerous trunks of _dadoxylon_ with the branches of _walchia_ and with fruits of the character of _trigonocarpa_, seems to show that these were parts of one and the same plant. this formation represents the upper barren measures of west virginia, which are well described by fontaine and white,[fl] and the reasons which these authors adduce for considering the latter equivalent to the european permian will apply to the more northern and eastern deposits as well, though these have afforded fewer species of plants, and are apparently less fully developed. [fl] "report on the permian flora of western virginia and south pennsylvania," . ( ) _coal-formation sub-flora_: the middle or productive coal-formation, containing all the beds of coal which are mined in nova scotia and cape breton, is the headquarters of the carboniferous flora. from this formation i have catalogued[fm] one hundred and thirty-five species of plants; but, as several of these are founded on imperfect specimens, the number of actual species may be estimated at one hundred and twenty. of these more than one half are species common to europe and america. no less than nineteen species are _sigillariæ_, and about the same number are _lepidodendra_. about fifty are ferns and thirteen are _calamites_, _asterophyllites_, and _sphenophylla_. the great abundance and number of species of sigillariæ, lepidodendra, and ferns are characteristic of this sub-flora; and among the ferns certain species of _neuropteris_, _pecopteris_, _alethopteris_, and _sphenopteris_ greatly preponderate. [fm] "acadian geology," and "report on flora of lower carboniferous," . these beds are the equivalents of the middle coal-measures, or productive coal-measures of pennsylvania, ohio, &c., and of the coal-formation proper of various european countries. very many of the species are common to nova scotia and pennsylvania; but in proceeding westward the number of identical species seems to diminish. ( ) _the millstone grit sub-flora_: in this formation the abundance of plants and the number of species are greatly diminished.[fn] trunks of coniferous trees of the species _dadoxylon acadianum_, having wide wood-cells with three or more series of discs and complex medullary rays, become characteristic. _calamites undulatum_ is abundant and seems to replace _c. suckovii_, though _c. cannæformis_ and _c. cistii_ continue. _sigillariæ_ become very rare, and the species of lepidodendron are few, and mostly those with large leaf-bases. _lepidophloios_ still continues, and _cordaites_ abounds in some beds. the ferns are greatly reduced, though a few characteristic coal-formation species occur, and the genus _cardiopteris_ appears. beds of coal are rare in this formation; but where they occur there is in connection with them a remarkable anticipation of the rich coal-formation flora, which would thus seem to have existed locally in the millstone grit period, but to have found itself limited by generally unfavorable conditions. in america, as in europe, it is in the north that this earlier development of the coal-flora occurs, while in the south there is a lingering of old forms in the newer beds. in newfoundland and cape breton, for instance, as well as in scotland, productive coal-beds and a greater variety of species of plants occur in this formation. [fn] "report on fossil plants of the lower carboniferous and millstone grit of canada," . the following would appear to be the equivalents of this formation, in flora and geological position: . the seral conglomerate of rogers in pennsylvania, &c. . the lower coal-formation conglomerate and chester groups of illinois (worthen). . the lower carboniferous sandstone of kentucky, alabama, and virginia. . the millstone grit and yoredale rocks of northern england, and the culmiferous of devonshire. . the moor rock and lower coal-measures of scotland. . flagstones and lower shales of the south of ireland, and millstone grit of the north of ireland. . the jüngste grauwacke of the hartz, saxony, and silesia. ( ) _the carboniferous limestone series_: this affords few fossil plants in eastern america, and in so far as known they are similar to those of the next group. in scotland it is richer in plants, but, according to mr. kidston, these are largely similar to those of the underlying beds, though with some species which extend upward into the millstone grit. in scotland the alga named _spirophyton_ and _archæocalamites radiatus_--which in america are erian--appear in this formation. ( ) _the lower carboniferous sub-flora_: this group of plants is best seen in the shales of the horton series, under the lower carboniferous marine limestones. it is small and peculiar. the most characteristic species are the following: _dadoxylon_ (_palæoxylon_) _antiquius_, dn.--a species with large medullary rays of three or more series of cells. _lepidodendron corrugatum_, dn.--a species closely allied to _l. veltheimianum_ of europe, and which is its american representative. this is perhaps the most characteristic plant of the formation. it is very abundant, and presents very protean appearances, in its old stems, branches, twigs, and _knorria_ forms. it had well-characterised stigmaria roots, and constitutes the oldest erect forest known in nova scotia. _lepidodendron tetragonum_, sternberg. _l. obovatum_, sternb. _l. aculeatum_, sternb. _l. dichotomum_, sternb. the four species last mentioned are comparatively rare, and the specimens are usually too imperfect to render their identification certain, but lepidodendra are especially characteristic trees of this horizon. _cyclopteris_ (_aneimites_) _acadica_, dn.--a very characteristic fern, allied in the form of its fronds to _c. tenuifolia_ of goeppert, to _c. nana_ of eichwald, and to _adiantites antiquus_ of stur. its fructification, however, is nearer to that of _aneimia_ than to that of _adiantum_. ferns of the genera cardiopteris and _hymenophyllites_ also occur, though rarely. _ptilophyton plumula_, dn.--this is the latest appearance of this erian genus, which also occurs in the lower carboniferous of europe and of the united states. _cordaites borassifolia_, brongt. on the whole, this small flora is markedly distinct from that of the millstone grit and true coal-formation, from which it is separated by the great length of time required for the deposition of the marine limestones and their associated beds, in which no land-plants have been found; nor is this gap filled up by the conglomerates and coarse arenaceous beds which, as i have explained in "acadian geology," in some localities take the place of the limestones, as they do also in the appalachian region farther south. the palæobotanical and stratigraphical equivalents of this series abroad would seem to be the following: . the vespertine group of rogers in pennsylvania. . the kinderhook group of worthen in illinois. . the marshall group of winchell in michigan. . the waverley sandstone (in part) of ohio. . the lower or false coal-measures of virginia. . the calciferous sandstones of mclaren, or tweedian group of tate in scotland. . the lower carboniferous slate and coomhala grits of jukes in ireland. . the culm and culm grauwacke of germany. . the graywacke or lower coal-measures of the vosges, as described by schimper. . the older coal-formation of the ural, as described by eichwald. . the so-called "ursa stage" of heer includes this, but he has united it with devonian beds, so that the name cannot be used except for the local development of these beds at bear island, spitsbergen. the carboniferous plants of arctic america, melville island, &c., as well as those of spitzbergen, appear all to be lower carboniferous.[fo] [fo] "notes on geological map of the northern portion of the dominion of canada," by dr. g. m. dawson, . all of the above groups of rocks are characterised by the prevalence of _lepidodendra_ of the type of _l. corrugatum_, _l. veltheimianum_, and _l. glincanum_; pines of the sub-genus _pitus_ of witham, _palæoxylon_ of brongniart, and peculiar ferns of the genera _cyclopteris_, _cardiopteris_, _triphyllopteris_, and _sphenopteris_. in all the regions above referred to they form the natural base of the great carboniferous system. in virginia, according to fontaine and white, types, such as archæopteris, which in the north are upper erian, occur in this group. unless there have been some errors in fixing the lower limit of the vespertine, this would indicate a longer continuance of old forms in the south. . erian flora. ( ) _upper erian sub-flora_: this corresponds to the catskill and chemung of the new york series, and to the upper devonian of europe. the flora of this formation, which consists mostly of sandstones, is not rich. its most distinctive species on both sides of the atlantic seem to be the ferns of the genus _archæopteris_, along with species referred to the genus _cyclopteris_, but which, in so far as their barren fronds are concerned, for the most part resemble _archæopteris_. the characteristic american species are _archæopteris jacksoni_, _a. rogersi_, and _a. gaspiensis_. _cyclopteris obtusa_ and _c._ (_platyphyllum_) _brownii_ are also very characteristic species. in europe, _archæopteris hibernica_ is a prevalent species. _leptophleum rhombicum_ and fragments of _psilophyton_ are also found in the upper erian. there is evidence of the existence of vast numbers of _rhizocarps_ in this period, in the deposits of spore-cases (_sporangites huronensis_) in the shales of kettle point, lake huron; and in deposits of similar character in ohio and elsewhere in the west. the upper erian flora is thus very distinct from that of the lower carboniferous, and the unconformable relation of the beds in the northeast may perhaps indicate a considerable lapse of time. still, even in localities where there appears to be a transition from the carboniferous into the devonian, as in the western states and in ireland, the characteristic flora of each formation may be distinguished, though, as already stated, there is apparently some mixture in the south. ( ) _middle erian sub-flora_: both in canada and the united states that part of the great erian system which may be regarded as its middle division, the hamilton and marcellus shales of new york, the cordaites shales of st. john, new brunswick, and the middle shales and sandstones of the gaspé series, presents conditions more favourable to the abundant growth of land-plants than either the upper or lower member. in the st. john beds, in particular, there is a rich fern flora, comparable with that of the coal-formation, and numerous stipes of ferns and trunks of tree-ferns have been found in the hamilton and corniferous series in the west, as well as trunks of _dadoxylon_. it is, however, distinguished by a prevalence of small and delicate species, and by such forms as _hymenophyllites_ and the smaller sphenopterids, and also by some peculiar ferns, as _archæopteris_ and _megalopteris_. in addition to ferns, it has small _lepidodendra_, of which _l. gaspianum_ is the chief. _calamiteæ_ occur, _archæocalamites radiatus_ being the dominant species. this plant, which in europe appears to reach up into the lower carboniferous, is so far strictly erian in northeast america. _sigillariæ_ scarcely appear, but _cordaites_ is abundant, and the earliest known species of _dadoxylon_ appear, while the psilophyton, so characteristic of the lower erian, still continues, and the remarkable aquatic plants of the genus _ptilophyton_ are locally abundant. ( ) _lower erian sub-flora_: this belongs to the lower devonian sandstones and shales, and is best seen in that formation at gaspé and the bay des chaleurs. it is equivalent to the oriskany sandstone, so far as its animal fossils and mineral character are concerned. it is characterised by the absence of true ferns, _calamites_ and _sigillariæ_, and by the presence of such forms as _psilophyton_, _arthrostigma_, _leptophleum_, and _nematophyton_. _lepidodendron gaspianum_ and _leptophleum_ already occur, though not nearly so abundant as psilophyton. the lower erian plants have an antique and generalised aspect which would lead us to infer that they are near the beginning of the land-flora, or perhaps in part belong to the close of an earlier flora still in great part unknown and few indications of land-plants have been found earlier. at campbellton and scaumenac bay, on the bay des chaleurs, fossil fishes of genera characteristic of the lower and upper devonian horizons respectively, occur in association with fossil plants of these horizons, and have been described by mr. whiteaves.[fp] [fp] "transactions of the royal society of canada." it is interesting to note that, as fontaine and white have observed, certain forms which are erian in the northeast are found in the lower members of the carboniferous in west virginia, indicating the southward march of species in these periods. . the silurian flora and still earlier indications of plants. in the upper beds of the silurian, those of the helderberg series, we still find _psilophyton_ and _nematophyton_; but below these we know no land-plants in canada. in the united states, lesquereux and claypole have described remains which may indicate the existence of lycopodiaceous and annularian types as far back as the beginning of the upper silurian, or even as low as the hudson river group, and hicks has found _nematophyton_ and _psilophyton_ in beds about as old in wales, along with the uncertain stems named _berwynia_. in the lower silurian the _protannularia_ of the skiddaw series in england may represent a land-plant, but this is uncertain, and no similar species has been found in canada. the cambrian rocks are so far barren of land-plants; the so-called _eophyton_ being evidently nothing but markings, probably produced by crustaceans and other aquatic animals. in the still older laurentian the abundant beds of graphite probably indicate the existence of plants, but whether aquatic or terrestrial it is impossible to decide at present. it would thus appear that our certain knowledge of land-vegetation begins with the upper silurian or the silurio-cambrian, and that its earliest forms were acrogens allied to lycopods, and prototypal trees, forerunners of the acrogens or the gymnosperms. in the lower devonian little advance is made. in the middle devonian this meagre flora had been replaced by one rivalling that of the carboniferous, and including pines, tree-ferns, and arboreal forms of lycopods and of equisetaceous plants, as well as numerous herbaceous plants. at the close of the erian the flora again became meagre, and continued so in the lower carboniferous. it again became rich and varied in the middle carboniferous, to decay in the succeeding permian. ii.--heer's latest results in the greenland flora. a very valuable report of prof. steenstrup, published in copenhagen in , the year in which heer died, contains the results of his last work on the greenland plants, and is so important that a summary of its contents will be interesting to all students of fossil botany or of the vicissitudes of climate which the earth has undergone.[fq] [fq] meddelelser om gronland, hefte v., copenhagen, . the plant-bearing beds of greenland are as follows, in ascending order: . cretaceous. . the _komé_ series, of black shales resting on the laurentian gneiss. these beds are found at various other localities, but the name above given is that by which they are generally known. their flora is limited to ferns, cycads, conifers, and a few endogens, with only _populus primæva_ to represent the dicotyledons. these beds are regarded as lower cretaceous (urgonian), but the animal fossils would seem to give them a rather higher position. they may be regarded as equivalent to the kootanie and queen charlotte beds in canada, and the potomac series in virginia. . the _atané_ series. these also are black shales with dark-coloured sandstones. they are best exposed at upernavik and waigat. here dicotyledonous leaves abound, amounting to ninety species, or more than half the whole number of species found. the fossil plants resemble those of the dakota series of the united states and the dunvegan series of canada, and the animal fossils indicate the horizon of the fort pierre or its lower part. they may be regarded as representing the lower part of the upper cretaceous. the genera _populus_, _myrica_, _quercus_, _ficus_, _platanus_, _sassafras_, _laurus_, _magnolia_, and _liriodendron_ are among those represented in these beds, and the peculiar genera _macclintockia_ and _credneria_ are characteristic. the genus _pinus_ is represented by five species, _sequoia_ by five, and _salisburia_ by two, with three of the allied genus _baiera_. there are many ferns and cycads. . the _patoot_ series. these are yellow and red shales, which seem to owe their colour to the spontaneous combustion of pyritous lignite, in the manner observed on the south saskatchewan and the mackenzie rivers. their age is probably about that of the fox-hill group or senonian, and the upper cretaceous of vancouver island, and they afford a large proportion of dicotyledonous leaves. the genera of dicotyledons are not dissimilar from those of atané, but we now recognise _betula_ and _alnus_, _comptonia_, _planera_, _sapotacites_, _fraxinus_, _viburnum_, _cornus_, _acer_, _celastrus_, _paliurus_, _ceanothus_, _zizyphus_, and _cratægus_ as new genera of modern aspect. on the whole there have been found in all these beds species, belonging to families, of which are dicotyledonous, and represent all the leading types of arborescent dicotyledons of the temperate latitudes. the flora is a warm temperate one, with some remarkable mixtures of sub-tropical forms, among which perhaps the most remarkable are _kaidocarpum_ referred to the _pandaneæ_, and such exogens as _ficus_ and _cinnamomum_. . tertiary. . the _unartok_ series. this is believed to be eocene. it consists of sandstone, which appears on the shores of disco island, and possibly at some other places on the coast. the beds rest directly and apparently conformably on the upper cretaceous, and have afforded only eleven species of plants. _magnolia_ is represented by two species, _laurus_ by two, _platanus_ by two, and one of these said to be identical with a species found by lesquereux in the laramie,[fr] _viburnum_, _juglans_, _quercus_, each by one species; the ubiquitous _sequoias_ by _s. langsdorfii_. this is pretty clearly a lower laramie flora. [fr] _viburnum marginatum_ of lesquereux. . the _atanekerdluk_ series, consisting of shaly beds, with limestone intercalated between great sheets of basalt, much like the eocene of antrim and the hebrides. these beds have yielded species, principally in bands and concretions of siderite, and often in a good state of preservation. they are referred to the lower miocene, but, as explained in the text, the flora is more nearly akin to that of the eocene of europe and the laramie of america. the animal fossils are chiefly fresh-water shells. _onoclea sensibilis_, several conifers, as _taxites_ _olriki_, _taxodium distichum_, _glyptostrobus europæus_, and _sequoia langsdorfii_, and of the dicotyledons are recognised as found also in american localities. of these, a large proportion of the more common species occur in the laramie of the mackenzie river and elsewhere in northwest canada, and in the western united states. it is quite likely also that several species regarded as distinct may prove to be identical. it would seem that throughout the whole thickness of these tertiary beds the flora is similar, so that it is probable it belongs altogether to the eocene rather than to the miocene. no indication has been observed of any period of cold intervening between the lower cretaceous and the top of the tertiary deposits, so that, in all the vast period which these formations represent, the climate of greenland would seem to have been temperate. there is, however, as is the case farther south, evidence of a gradual diminution of temperature. in the lower cretaceous the probable mean annual temperature in latitude ° north is stated as ° to ° centigrade, while in the early tertiary it is estimated at ° centigrade. such temperatures, ranging from ° to ° of fahrenheit, represent a marvellously warm climate for so high a latitude. in point of fact, however, the evidence of warm climates in the arctic regions, in the palæozoic as well as in the mesozoic and early tertiary, should perhaps lead us to conclude that, relatively to the whole of geological time, the present arctic climate is unusually severe, and that a temperate climate in the arctic regions has throughout geological time been the rule rather than the exception. iii.--mineralisation of fossil plants. the state of preservation of fossil plants has been referred to incidentally in several places in the text; but the following more definite statements may be of service to the reader. i. organic remains imbedded in aqueous deposits may occur in an unchanged condition, or only more or less altered by decay. this is often the case with such enduring substances as bark and wood, and even with leaves, which appear as thin carbonaceous films when the layers containing them are split open. in the more recent deposits such remains occur little modified, or perhaps only slightly changed by partial decay of their more perishable parts. in the older formations, however, they are usually found in a more or less altered condition, in which their original substance has been wholly or in part changed into coaly, or bituminous, or anthracitic or graphitic matter, so that leaves are sometimes represented by stains of graphite, as if drawn on stone with a lead-pencil. yet even in this case some portion of the original substance remains, and without any introduction of foreign material. ii. on the other hand, such remains are often mineralised by the filling of their pores or the replacement of their tissues with mineral matter, so that they become hard and stony, and sometimes retain little or nothing of their original substance. the more important of these changes, in so far as they affect fossil plants, may be arranged under the following heads: (_a_) _infiltration_ of mineral matter which has penetrated the pores of the fossil in a state of solution. thus the pores of fossil wood are often filled with calcite, quartz, oxide of iron, or sulphide of iron, while the woody walls of the cells and vessels remain in a carbonised state, or converted into coaly matter. when wood is preserved in this way it has a hard and stony aspect; but we can sometimes dissolve away the mineral matter, and restore the vegetable tissue to a condition resembling that before mineralisation. this is especially the case when calcite is the mineralising substance. we sometimes find, on microscopic examination, that even cavities so small as those of vegetable cells and vessels have been filled with successive coats of different kinds of mineral matter. (_b_) organic matters may be entirely _replaced_ by mineral substances. in this case the cavities and pores have been first filled, and then--the walls or solid parts being removed by decay or solution--mineral matter, either similar to that filling the cavities, or differing in colour or composition, has been introduced. silicified wood often occurs in this condition. in the case of silicified wood, it sometimes happens that the cavities of the fibers have been filled with silica, and the wood has been afterward removed by decay, leaving the casts of the tubular fibers as a loose filamentous substance. some of the tertiary coniferous woods of california are in this state, and look like asbestus, though they show the minute markings of the tissue under the microscope. in the case of silicified or agatized woods, it would seem that the production of carbon dioxide from the decaying wood has caused the deposition of silica in its place, from alkaline solutions of that substance, and thus the carbon has been replaced, atom by atom, by silicon, until the whole mass has been silicified, yet retaining perfectly its structure. (_c_) the cavities left by fossils which have decayed may be filled with clay, sand, or other foreign matter, and this, becoming subsequently hardened into stone, may constitute a _cast_ of the fossils. trunks of trees, roots, &c., are often preserved in this way, appearing as stony casts, often with the outer bark of the plant forming a carbonaceous coating on their surfaces. in connection with this state may be mentioned that in which, the wood having decayed, an entire trunk has been flattened so as to appear merely as a compressed film of bark, yet retaining its markings; and that in which the whole of the vegetable matter having been removed, a mere impression of the form remains. fossils preserved in either of the modes, (_a_) or (_b_), usually show more or less of their minute structures under the microscope. these may be observed:--( ) by breaking off small splinters or flakes and examining them, either as opaque or as transparent objects. ( ) by treating the material with acids, so as to dissolve out the mineral matters, or portions of them. this method is especially applicable to fossil woods mineralised with calcite or pyrite. ( ) by grinding thin sections. these are first polished on one face on a coarse stone or emery hone, and then on a fine hone, then attached by the polished face to glass slips with a transparent cement or canada balsam, and ground on the opposite face until they become so thin as to be translucent. in most cities there are lapidaries who prepare slices of this kind; but the amateur can readily acquire the art by a little practice, and the necessary appliances can be obtained through dealers in minerals or in microscopic materials. very convenient cutting and polishing machines, some of them quite small and portable, are now made for the use of amateurs. in the case of exogenous woods, three sections are necessary to exhibit the whole of the structures. one of these should be transverse and two longitudinal, the latter in radial and tangential planes. iv.--general works on palÆobotany. in the text frequent reference has been made to special memoirs and reports on the fossil plants of particular regions or formations. there are, however, some general books, useful to students, which may be mentioned here. perhaps the most important is schimper's "traité de paléontologie végétale." very useful information is also contained in renault's "cours de botanique fossile," and in balfour's "introduction to palæontological botany," and nicholson's "palæontology." unger's "genera et species," brongniart's "histoire des végétaux fossiles," and lindley and button's "fossil flora," are older though very valuable works. williamson's "memoirs," in the "philosophical transactions," have greatly advanced our knowledge of the structures of palæozoic plants. lastly, the "palæophytology" of schenk, now in course of publication in german and french, in connection with zittel's "palæontology," is an important addition to manuals of the subject. index. acer, . acrogens, . agassiz, prof., . alaska, flora of, . algæ, real and spurious, , . amboy clays, flora of, . america, cretaceous of, . angiosperms, . annularia, . anogens, . antholithes, . aporoxylon, . araucarioxylon, . araucarites, . archæocalamites, . archæopteris, , . arctic origin of plants, , . arthrophycus, . arthrostigma, . asterophyllites, , , . asteropteris, , . astropolithon, . atané, plants of, , . atanekerdluk, plants of, . australia, palæozoic flora of, . tertiary flora of, . bauhinia, . bear island, . betula, . bilobites, . bovey tracey, plants of, . brasenia, . buckland, dr., . buthotrephis, . calamites, , , . calamodendron, . cambrian flora, . canada, erian of, . carboniferous of, . laramie of, . pleistocene of, . carbon in laurentian, . carboniferous flora, . carboniferous, climate of, . of southern hemisphere, . cardiocarpum, , . carruthers, mr., , , . on modifications of modern plants, , . carya, . cauda-galli fucoid, . caulerpites, . caulopteris, , . clarke, prof., . climate, causes of, . climate and plants, , , . of carboniferous, . of cretaceous and eocene, . of devonian, . of early mesozoic, . climate and plants of laurentian, . of pleistocene, , . of pliocene, . coal, origin of, , . comparison of floras, . composite, . cone-in-cone, . coniferæ, erian, , . carboniferous, , . mesozoic, etc., . cope, mr., . cordaites, , , . corylus, . crepin, m., . cretaceous, flora of, . climate of, . croll on climate, . cromer, plants of, . cycads, mesozoic, . cyclostigma, . dadoxylon, , , . dawson, dr. g. m., , . delgado, prof., . dendrophycus, . derby, orville, . devonian flora, . devonian or erian, , . climate of, . dicotyledons, cretaceous, . table of, . dictyolites, . dictyospongia, . disco, exotic plants at, . flora of, , . drepanophycus, . drosera, . dunvegan beds, . eocene, flora of, , . climate of, . eophyton, . eopteris, . eozoon of laurentian, . equisetum, , . erian flora, , . climate of, . erian or devonian, . ettingshausen, dr., , . exogens, cretaceous, . tertiary, , . fagus, , . ferns, erian, . carboniferous, , . fructification of, . stems of, , . tertiary, . filices, , , . flora of cambrian, . of carboniferous, , . of cretaceous, . of early mesozoic, . of erian, , . of jurassic, , . of laramie, . of laurentian, . of miocene, , . of modern, . of permian, . of pleistocene, , . of tertiary, , , , . fontaine, prof., , . fontinalis, . fort union beds, . fucoids, . gardner, mr. starkie, . geinitz, dr., . geological formations, table of, . glossopteris, . glyptodendron, . glyptostrobus, . goeppert, dr., . grant, col., . graphite from plants, . gray, dr., origin of floras, , . greenland, climate of, . fossil flora of, . gulielmites, . gymnosperms, . haliserites, . hartt, prof., . heer, dr., , . helderberg period, sea of, . heterangium, . hicks, dr., . hunt, dr. sterry, , . huxley, prof., . hymenæa, . insects, erian, . juglans, . jurassic flora, . kainozoic flora, , , , . kidston, mr. r., , . king, mr. clarence, . komé, plants of, , . laramie flora, , . laurentian plants, . laurentian, climate of, . laurophyllum, . laws of introduction of plants, , . leda clay, flora of, . lepidodendron, , , . lepidophloios, , , . leptophleum, . lesquereux, mr. l., , . licrophycus, . lignitic series of america, . liquidambar, . liriodendron, . lower carboniferous flora, . logan, sir w., . lyell on climate, . magnolia, . mcconnell, mr., . mcnab, prof., . megalopteris, . megaphyton, . mesozoic flora, . climate of, . migrations of plants, , . miller, hugh, . miocene flora, . miocene, supposed, . modern flora, . modern plants, how modified, . modifications of plants, . nathorst, dr., , . nematodendreæ, . nematophycus, . nematophyton, , , . newberry, dr., , , . newfoundland, fossil plants of, . newton, mr., . nicholson, dr. a., . niobrara series, , . noeggerathia, . northern origin of plants, . origin of plants, . orton, prof., . pachytheca, . palæanthus, . palæochorda, . palæophycus, , . palæozoic floras compared, . palms, , . pandanus, . patoot beds, . peach, mr., . petroleum, origin of, . phymatoderma, . plants, classification of, . platanus, . platyphyllum, . pleistocene climate, , . pleistocene flora, , . pliocene climate, . podozamites, . poles, supposed change of, . populus, , . potamogeton, . potentilla, . protannularia, . protichnites, . protophyllum, . protosalvinia, . protostigma, . prototaxites, . psaronius, . psilophyton, . ptilophyton, , . quercus, . rhizocarps, . rill-marks, . rusichnites, . saccamina, . salisburia, . salter, mr., . salvinia, . saporta, count de, , . saportea, . sassafras, . scalariform tissue, . schimper, dr., , , . scolithus, . scottish devonian, . sequoia, . shrinkage cracks, . sigillaria, , , . southern hemisphere, , . carboniferous in, . tertiary in, . sphenophyllum, , , . spirophyton, . spitzbergen, . sterculites, . sternbergia, , . stigmaria, . stur, dr., on sigillaria, . symphorocarpus, . syringodendron, . syringoxylon, . table of formations, . tasmania, fossil plants of, , . tasmanite, . tertiary period, flora of, , , , . tertiary of australia, . thallogens, . thomas, mr., . thuja, , . time, geological, 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lore [illustration: plate i orographic map of scotland] fragments of earth lore sketches & addresses geological and geographical by james geikie, d.c.l., ll.d., f.r.s., &c. murchison-professor of geology and mineralogy in the university of edinburgh formerly of h.m. geological survey of scotland with maps and illustrations edinburgh john bartholomew & co. london: simpkin, marshall, hamilton, kent & co., ltd. preface. the articles in this volume deal chiefly with the history of glacial times and the origin of surface-features. as they were not written with any view to their subsequent appearance in a collected form, each is so far independent and complete in itself. under these circumstances some repetition was unavoidable, if the articles were not to be recast, and i did not think it advisable to make such radical alteration. with the exception of verbal changes and some excisions, therefore, the papers remain substantially in their original state. here and there a footnote has been added to indicate where the views expressed in the text have since been modified; but i have not been careful to insert such notes throughout. geologists, like other folk, live and learn, and the reader will probably discover that the opinions set forth in some of the later articles are occasionally in advance of those maintained in the writer's earlier days. i have to thank the publishers of _good words_ for allowing me to republish the articles on the cheviot hills and the outer hebrides. my acknowledgments are also due to mr. bartholomew for the excellent maps with which the volume is so well illustrated. edinburgh, _april th, _. list of maps. plate i. physical features of scotland _frontispiece_ " ii. structure of mountains " iii. past and present glaciation of the world " iv. ice age in northern europe " v. the geographical evolution of continents " vi. bathy-hypsometrical map, illustrating development of coast-lines contents. chap. page i. geography and geology ii. the physical features of scotland iii. mountains: their origin, growth, and decay iv. the cheviot hills v. the long island, or outer hebrides vi. the ice age in europe and north america vii. the intercrossing of erratics in glacial deposits viii. recent researches in the glacial geology of the continent ix. the glacial period and the earth-movement hypothesis x. the glacial succession in europe xi. the geographical evolution of europe xii. the evolution of climate xiii. the scientific results of dr. nanssen's expedition xiv. the geographical development of coast-lines i. geography and geology.[a] [a] portion of a lecture given in to the class of geology in the university of edinburgh. the teaching of geography naturally occupies a prominent place in every school curriculum. it is rightly considered essential that we should from an early age begin to know something of our own and other countries. i am not sure, however, that geography is always taught in the most interesting and effective manner. indeed, according to some geographers, who are well qualified to express an opinion, the manner in which their subject is presented in many of our schools leaves much to be desired. but a decided advance has been made in recent years, and with the multiplication of excellent text-books, maps, and other appliances, i have no doubt that this improvement will continue. when i attended school the text-books used by my teachers were about as repellent as they could be. our most important lesson was to commit to memory a multitude of place-names, and the maps which were supposed to illustrate the text-books were, if possible, less interesting and instructive. nowadays, however, teachers have a number of more or less excellent manuals at their service, and the educational maps issued by our cartographers show in many cases a very great advance on the bald and misleading caricatures which did duty in my young days as pictures of the earth's surface. during the progress of some war we often remark that the task of following the military operations compels us to brush up our geography. i am uncharitable enough to suspect that it would frequently be truer to say that, before these campaigns commenced, we had no such knowledge to brush up. the countries involved in the commotion were probably mere names to many of us. we had no immediate interest in them or their inhabitants, and had we been asked, before the outbreak of hostilities, to indicate the precise positions of the places upon a map, some of us perhaps might have been sorely puzzled to do so. nor is such ignorance always discreditable. one cannot know everything; the land-surface of the globe contains upwards of millions of square miles, and one may surely be excused for not having a detailed knowledge of this vast area. i have referred to the subject simply because i think it gives us a hint as to how the teaching of political geography might be made most instructive and interesting. historical narrative might often be interwoven with the subject in such a way as to fix geographical features indelibly on the memory. striking and picturesque incidents, eventful wars, the rise and progress of particular trades, the routes followed by commerce, the immigration and emigration of races, the gradual development of the existing political divisions of the old world, the story of columbus and the early voyagers, the geographical discoveries of later times--all these, and such as these, might be introduced into our lessons in political geography. the wanderings of a mungo park, a bruce, a livingstone, a stanley, traced on a good map, could not fail to arrest the attention of the youthful student of african geography. in like manner, the campaigns of the great napoleon might be made to do good service in illustrating the geographical features of large portions of our own continent. then, as regards britain, what a world of poetry and romantic story clings to every portion of its surface--why, the very place-names themselves might suggest to any intelligent teacher themes and incidents, the deft treatment of which would make the acquisition of geography a delightful task to the dullest boy or girl. the intimate relation that obtains between political geography and history has indeed long been recognised, and is in fact self-evident. and we are all well aware that in our school manuals of geography it has been usual for very many years to note the scenes of remarkable events. such notes, however, are of necessity extremely brief; and it need hardly be said that to fully incorporate history in a text-book of general geography would be quite impracticable. it might be done to a certain extent for our own and a few of the more important countries; but similar detail need not be attempted in regard to regions which are of less consequence from the political point of view. indeed, i should be inclined to leave the proper application of historical knowledge in the teaching of geography very much to the teacher himself, who would naturally select such themes and incidents as seemed best adapted to attract the attention of his pupils. be that, however, as it may, it is enough for my present purpose if i insist upon the fact that the proper study of political geography involves the acquisition of some historical knowledge. one can hardly conceive the possibility of an intelligent student taking pains to become acquainted with the political geography of a country without at the same time endeavouring to learn something of its history--otherwise, his geographical attainments would hardly surpass those of a commercial traveller, whose geographical studies have been confined to the maps and tables of his bradshaw. but if it be impossible to ignore history in the teaching of political geography, it is just as impossible to exclude from our attention great physical features and characteristics. surface-configuration, climate, and natural products all claim our attention. it is obvious, in fact, that the proper study of political geography must give us at least a general notion of the configuration, the river-systems, and climatic conditions of many different lands. for has not the political development of races depended most largely on the physical conditions and natural resources of the countries occupied by them? so far, then, as these have sensibly influenced the progress of peoples, they come naturally under the consideration of political geography. thus, if political geography be closely connected and interwoven, as it were, with history, not less intimate are its relations to physical geography. it does not embrace all physical geography, but it introduces us to many facts and phenomena, the causes and mutual relations of which we cannot understand without first mastering the teachings of physical geography. in the study of this latter science we come more closely into contact with nature; we cease to think of the surface of the earth as parcelled out into so many lots by its human occupants--we no longer contemplate that surface from the limited point of view of the political geographer--we are now not merely members of one particular community, but have become true citizens of the world. to us north and south, east and west are of equal interest and importance. our desire now is to understand, if haply we may, the complex system of which we ourselves form a part. the distribution of land and water--the configuration of continental areas and oceanic basins--the circulation of oceanic and terrestrial waters--earth-movements and volcanoes--ice-formations--the atmosphere--climatology--the geographical distribution of plants and animals--in a word, _the world as one organic whole_ now forms the subject of our contemplation. such being the scope of physical geography, it is satisfactory to know that its importance as a subject of study in our schools has been fully recognised. this being admitted, i shall now proceed to show that physical geography, although, like political geography, it is a separate and distinct subject, yet, just as the study of the latter involves some knowledge of history, so the prosecution of physical geography compels us to make a certain acquaintance with geology. we cannot, in fact, learn much about the atmosphere, about rain and rivers, glaciers and icebergs, earthquakes and volcanoes, and the causes of climate, without at the same time becoming more or less familiar with the groundwork on which geological investigations are based. and just as a knowledge of history enables us better to understand the facts of political geography, so some acquaintance with the results of geological inquiry are necessary before we can hope to comprehend many of the phenomena of which physical geography treats. let me try to make this plain. the physical geographer, we shall suppose, is considering the subject of terrestrial waters. he tells us what is meant by the drainage-system of a country, points out how the various minor water-courses or brooks and streams unite to form a river, describes for us the shape of the valley through which a typical river makes its way--how the valley-slope diminishes from the mountains onwards to the sea-coast--how, at first, in its upper or mountain-track, the flow of the river is torrential--how, as the slope of the valley decreases, the river begins to wind about more freely, until it reaches the head of its plain-track or delta, when, no longer receiving affluents, it begins to divide, and enters the sea at last by many mouths. he tells us further what proportion of the rainfall of the country passes seawards in our river, and he can measure for us the quantity of water which is actually discharged. all this is purely physical geography; but when we come to ask why some rivers flow in deep cañons, like those of the colorado--why valleys should widen out in one part and contract, as it were, elsewhere--why the courses of some rivers are interrupted by waterfalls and rapids, and many other similar questions, the physical geographer must know something of geology before he can give an answer. he can describe the actual existing conditions; without the aid of geology, he can tell us nothing of their origin and cause. so the political geographer can map out for us the present limits of the various countries of europe, but history must be invoked if we would know how those boundaries came to be determined. the moment, therefore, the physical geographer begins to inquire into the origin of any particular physical feature, he enters upon the domains of the geologist. and as he cannot possibly avoid doing so, it is quite common now to find a good deal of the subject-matter of geology treated of in text-books of physical geography. i state this merely to show how very closely the two sciences are interlocked. take, for example, the configuration of river valleys just referred to. the physical geographer recognises the fact that a river performs work; by means of the sediment which it carries in suspension and rolls along its course, it erodes its bed in many places, and undermines its banks, and thus its channel is deepened and widened. he can measure the amount of sediment which it carries down to the sea, and the quantity of saline matters which its waters hold in solution: and knowing that all these substances have been abstracted from the land, he is able to estimate approximately the amount of material which is annually transferred from the surface of the drainage-area involved. he discovers this to be so relatively enormous that he has no difficulty in believing that the valleys in which rivers flow might have been hollowed out by the rivers themselves. but, without trespassing further into the geologist's domains, he cannot go beyond this: and you will at once perceive that something more is required to prove that any particular valley owes its origin to the erosive action of running water. suppose someone were to suggest to him that his river-valley might be a minor wrinkle in the earth's crust caused by earth-movements, or that it might indicate the line of a fissure or dislocation, due to some comparatively recent convulsion--how could his computation of the amount of material at present carried seawards by the river prove such suggestions to be erroneous? and what light could it throw upon the origin of the varied configuration of the river-valley--how would it explain the presence or absence of cascades and rapids, of narrow gorges and open expanses? none of these phenomena can be interpreted and accounted for without the aid of the geologist: without some knowledge of rocks and rock-structures, the origin of the earth's surface-features is quite inexplicable. to give an adequate explanation of all the surface-features of a country in detail would of course require a profound study of geology; but a general acquaintance only with its elementary facts is quite sufficient to enable us to form a reasonable and intelligent view of the cause and origin of the main features of the land as a whole. thus a few lessons in elementary geology would make clear to any child how rivers have excavated valleys, why cataracts and gorges occur here, and open valleys with gently-flowing waters elsewhere. let me select yet another example to show how dependent physical geography is upon geology. the physical geographer, in describing the features of the land, tells us how the great continental areas are traversed in various directions by what he calls mountain-chains. thus, in speaking of america, he tells us that it may be taken as a type of the continental structure--namely a vast expanse of land, low or basin-like in the interior, and flanked along the maritime regions by elevated mountain borders--the highest border facing the deepest ocean. he points out further that the great continental areas are crossed from west to east by well-marked depressions, to a large extent occupied by water. thus europe is separated from africa by the mediterranean, a depression which is continued eastward through the black sea into the aralo-caspian area. south america is all but cut away from north america, while australia is separated from asia by the east india seas. we find, in fact, all over the world that well-marked natural features are constantly being repeated. not only do the great land-masses of the globe bear certain resemblances to each other, but even in their detailed structure similar parallelisms recur. the physical geographer notes all these remarkable phenomena, but he can give us no clue to their meaning. he may describe with admirable skill the characteristic features of plains and plateaux, of volcanic mountains and mountain-chains, but he cannot tell us why plains should occur here and mountains there; nor can he explain why some mountains, such as those of scotland or norway, differ so much in configuration from the alps and the pyrenees. the answer to all these questions can only be given by geology. it is from this science we learn how continental areas and oceanic basins have been evolved. the patient study of the rocks has revealed the origin of the present configuration of the land. there is not a hill or valley, not a plateau or mountain-region, which does not reveal its own history. the geologist can tell you why continents are bordered by coast-ranges, and why their interiors are generally comparatively low and basin-shaped. the oceanic basins and continental areas, we learn, are primeval wrinkles in the earth's crust, caused by its irregular subsidence upon the gradually cooling and contracting nucleus. the continents are immense plateau-like areas rising more or less abruptly above those stupendous depressions of the earth's crust which are occupied by the ocean. while those depressions are in progress the maritime borders of the land-areas are subjected to enormous squeezing and crushing, and coast-ranges are the result--the elevation of those ranges necessarily holding some relation to the depth of the contiguous ocean. for, the deeper the ocean the greater has been the depression under the sea, and, consequently, the more intense the upheaval along the continental borders. it is for the same reason that destructive earthquakes are most likely to occur in the vicinity of coast-ranges which are of comparatively recent geological age. these, and indeed all, mountains of elevation are lines of weakness along which earth-movements may continue from time to time to take place. but all mountains are not mountains of elevation; many elevated regions owe their mountainous character simply to the erosive action of sub-aërial agents, such as rain, frost, ice, and running water, the forms assumed by the mountains being due to their petrological character and geological structure. there are, for example, no true mountains of elevation in scotland; hence to write of the _chain of the grampians_ or the _range of the lowthers_ is incorrect and actually misleading. without the aid of geology the geographer cannot, in fact, discriminate between mountains of elevation and mountains of denudation; hence geographical terms so constantly in use as _mountain-range_ and _mountain-chain_ are very often applied by writers, ignorant of geological structure, to elevated regions which have no claim to be described either as _chains_ or _ranges_. some knowledge of geology, therefore, is essential to us if we would have correct views of many of the grandest features of the globe. but it will be said that, after all, the physical geographer deals with the earth as we now find it; he does not need to trouble himself with the origin of the phenomena he describes. well, as i have just shown, he cannot, even if he would, escape trenching on geology; and if he could, his subject would be shorn of much of its interest. he recognises that the world he studies has in it the elements of change--the forces of nature are everywhere modifying the earth's surface--considerable changes are sometimes brought about even in one's lifetime, while within the course of historical ages still greater mutations have taken place--he becomes conscious, in short, that the existing state of things is but the latest phase of an interminable series of changes stretching back into the illimitable past, and destined to be prolonged into the indefinite future. thus he gladly welcomes the labours of the geologist, whose researches into the past have thrown such a flood of light upon the present. in fact, he can no more divorce his attention from the results of geological inquiry than the political geographer can shut his eyes to the facts of history. let me, in conclusion, give one further illustration of the close inter-dependence of the two sciences of which i am speaking. one of the subjects treated of by physical geography is the present geographical distribution of plants and animals. the land-surface of the globe has been mapped out into so many biological regions, each of which is characterised by its special fauna and flora. the greatest changes in the flora and fauna of a continent are met with as we pass from south to north, or _vice versa_. proceeding in the direction of the latitude, the changes encountered are much less striking. now, these facts are readily explained by the physical geographer, who points out that the distribution is due chiefly to climatic conditions--a conclusion which is obvious enough. but when we go into details we find that mere latitude will not account for all the phenomena. take, for example, the case of the scandinavian flora of our own continent. it is true that this flora is largely confined to northern latitudes; but isolated colonies occur in our own mountains and in the mountains of middle and southern europe. how are these to be accounted for? the physical geographer says that the plants grow there simply because they obtain at high levels in low latitudes the favourable climatic conditions underneath which they flourish at low levels in high latitudes. he therefore concludes that the distribution of life-forms is due to varying climatic and physical conditions. but if we ask him how those curious colonies of foreigners come to be planted on our mountains, he cannot tell. to get our answer we must come to the geologist; and he will explain that they are, as it were, living fossils--monuments of former great physical and climatic changes. he will prove to us that the climate of europe was at a recent geological period so cold that the scandinavian flora spread south into middle europe, where it occupied the low grounds. when the climate became milder, then the northern invaders gradually retired--the main body migrating back to the north--while some stragglers, retreating before the stronger germanic flora, took shelter in the mountains, whither the latter could not or would not follow, and so there our scandinavians remain, the silent witnesses of a stupendous climatic revolution. now, all the world over, plants and animals have similar wonderful tales to tell of former geographical changes. the flora and fauna of our country, for example, prove that the british islands formed part of the continent at a very recent geological period; and so, from similar evidence, we know that not long ago europe was joined on to africa. on the other hand, the facts connected with the present distribution of life demonstrate that some areas, such as australia, have been separated from the nearest continental land for vastly prolonged periods of time. it would be a very easy matter to adduce many further illustrations to show how close is the connection between the studies of the physical geographer and the geologist. i do not indeed exaggerate when i say that no one can hope to become a geologist who is not well versed in physical geography; nor, on the other hand, can the physical geographer possibly dispense with the aid of geology. the two subjects are as closely related and interwoven, the one with the other, as history is with political geography. i do not see therefore how educationists who have admitted the great importance of physical geography as a branch of general education, can logically exclude geology as a subject of instruction in schools. already, indeed, it has been introduced by many teachers, and i am confident that ere long it will be as generally taught as physical geography. i would not, however, present the subject to young people as a lesson to be learned from books. a good teacher should be able to dispense with these helps, or rather hindrances--for such they really are to a young beginner. his pupils ought to have previously studied the subject of physical geography, and if they have been well taught they ought to have already acquired no mean store of geological knowledge. they ought, in fact, to have learned a good deal about the great forces which are continually modifying the surface of the globe, and what they have now to do is to study more particularly the results which have followed from the constant operation of those forces. we shall suppose, for example, that the teacher has described how rivers erode their channels, and waves tend to cut back a coast-line, and how the products of erosion, consisting of gravel, sand, and mud, are distributed along river-valleys and accumulated in lakes and seas. he now exhibits to his class good-sized fragments of conglomerate, sandstone, and shale, and points out how each of these rocks is of essentially the same character, and must therefore have had the same origin, as modern sedimentary accumulations. his pupils should be encouraged to examine the rocks of their own neighbourhood, whether exhibited in natural sections or artificial exposures, and to compare these with the products of modern geological action. one hour's instruction in the field is, in fact, worth twenty hours of reading or listening to lectures. knowledge at first hand is what is wanted. there are many excellent popular or elementary treatises dealing with historical geology, and these have their uses, and may be read with profit as well as pleasure. but the mere reading of such books, it is needless to say, will never make us geologists. they help no doubt to store the mind with interesting and entertaining knowledge, but they do not cultivate the faculties of observation and reasoning. and unless geology is so taught as to accomplish this result, i do not see why it should enter into any school curriculum. further, i would remark that, however interesting a geological treatise may be, it cannot possibly stimulate the imagination as the practical study of the science is bound to do. one may put into the hands of a youth a clear and well-written description of some particular fossiliferous limestone, and he may by dint of slavish toil be able to repeat verbatim all that he has read. that is how a good deal of book-knowledge of science is acquired. only think, however, of the drudgery it involves--the absolute waste of time and energy. but let us illustrate our lesson by means of a lump of the limestone itself; let us show him the character of the rock and the nature of its fossil contents, and his difficulties disappear. better still--let us take him, if we can, into a limestone quarry, and he will be a dull boy indeed if he fails fully to understand what limestone is, or to realise the fact that the rock he is looking at accumulated slowly, like existing oceanic formations, at the bottom of a sea that teemed with animal life. it is unnecessary, however, that i should illustrate this subject further. i would only repeat that the beginner should be taught from the very first to use his own eyes, and to draw logical conclusions from the facts which he observes. trained after this manner, he would acquire, not only a precise and definite knowledge of what geological data really are, but he would learn also how to interpret those data. he would become familiar, in fact, with the guiding principles of geological inquiry. how much or how little of historical geology should be given in schools will depend upon circumstances. great care, however, should be taken to avoid wearying the youthful student with strings of mere names. what good is gained by learning to repeat the names of fifty or a hundred fossils, if you cannot recognise any one of these when it is put into your hand? with young beginners i should not attempt anything of that kind. if the neighbourhood chanced to be rich in fossils, i should take my pupils out on saturday to the sections where they were found, and let them ply their hammers and collect specimens for themselves. i should describe no fossils which they had not seen and handled. of the more remarkable forms of extinct animals and plants, which are often represented by only fragmentary remains, i should exhibit drawings showing the creatures as they have been restored by the labours of comparative anatomists. such restorations and ideal views of geological scenes like those given by heer, dana, saporta, and others, convey far more vivid impressions of the life of a geological period than the most elaborate description. in fine, the story of our earth should be told much in the same manner as scott wrote the history of scotland for his grandson. there is no more reason for requiring the juvenile student to drudge through minute geological data before introducing him to the grand results of geological investigation, than there is for compelling him to study the manuscripts in our record offices before allowing him to read the history which has been drawn from these and similar sources of information. it is enough if at the beginning of his studies he has already learned the general nature of geological evidence and the method of its interpretation. provided with such a stock of geological knowledge as i have indicated, our youth would leave school with some intelligent appreciation of existing physical conditions, and a not inadequate conception of world-history. ii. the physical features of scotland.[b] [b] _scottish geographical magazine_, vol. i., . scotland, like "all gaul," is divided into three parts, namely, the highlands, the central lowlands, and the southern uplands. these, as a correctly drawn map will show, are natural divisions, for they are in accordance not only with the actual configuration of the surface, but with the geological structure of the country. the boundaries of these principal districts are well defined. thus, an approximately straight or gently undulating line taken from stonehaven, in a south-west direction, along the northern outskirts of strathmore to glen artney, and thence through the lower reaches of loch lomond to the firth of clyde at kilcreggan, marks out with precision the southern limits of the highland area and the northern boundary of the central lowlands. the line that separates the central lowlands from the southern uplands is hardly so prominently marked throughout its entire course, but it follows precisely the same north-east and south-west trend, and may be traced from dunbar along the base of the lammermoor and moorfoot hills, the lowthers, and the hills of galloway and carrick, to girvan. in each of the two mountain-tracts--the highlands and the southern uplands--areas of low-lying land occur, while in the intermediate central lowlands isolated prominences and certain well-defined belts of hilly ground make their appearance. the statement, so frequently repeated in class-books and manuals of geography, that the mountains of scotland consist of three (some writers say five) "ranges" is erroneous and misleading. the original author of this strange statement probably derived his ignorance of the physical features of the country from a study of those antiquated maps upon which the mountains of poor scotland are represented as sprawling and wriggling about like so many inebriated centipedes and convulsed caterpillars. properly speaking, there is not a true mountain-range in the country. if we take this term, which has been very loosely used, to signify a linear belt of mountains--that is, an elevated ridge notched by cols or "passes" and traversed by transverse valleys--then in place of "three" or "five" such ranges we might just as well enumerate fifty or sixty, or more, in the highlands and southern uplands. or, should any number of such dominant ridges be included under the term "mountain-range," there seems no reason why all the mountains of the country should not be massed under one head and styled the "scottish range." a mountain-range, properly so called, is a belt of high ground which has been ridged up by earth-movements. it is a fold, pucker, or wrinkle in the earth's crust, and its general external form coincides more or less closely with the structure or arrangement of the rock-masses of which it is composed. a mountain-range of this characteristic type, however, seldom occurs singly, but is usually associated with other parallel ranges of the same kind--the whole forming together what is called a "mountain-chain," of which the alps may be taken as an example. that chain consists of a vast succession of various kinds of rocks, which at one time were disposed in horizontal layers or strata. but during subsequent earth-movements those horizontal beds were compressed laterally, squeezed, crumpled, contorted, and thrown, as it were, into gigantic undulations and sharper folds and plications. and, notwithstanding the enormous erosion or denudation to which the long parallel ridges or ranges have been subjected, we can yet see that the general contour of these corresponds in large measure to the plications or foldings of the strata. this is well shown in the jura, the parallel ranges and intermediate hollows of which are formed by undulations of the folded strata--the tops of the long hills coinciding more or less closely with the arches, and the intervening hollows with the troughs. now folded, crumpled, and contorted rock-masses are common enough in the mountainous parts of scotland, but the configuration of the surface rarely or never coincides with the inclination of the underlying strata. the mountain-crests, so far from being formed by the tops of great folds of the strata, frequently show precisely the opposite kind of structure. in other words, the rocks, instead of being inclined away from the hill-tops like the roof of a house from its central ridge, often dip into the mountains. when they do so on opposite sides the strata of which the mountains are built up seem arranged like a pile of saucers, one within another. there is yet another feature which brings out clearly the fact that the slopes of the surface have not been determined by the inclination of the strata. the main water-parting that separates the drainage-system of the west from that of the east of scotland does not coincide with any axis of elevation. it is not formed by an anticlinal fold or "saddleback." in point of fact it traverses the strata at all angles to their inclination. but this would not have been the case had the scottish mountains consisted of a chain of true mountain-ranges. our mountains, therefore, are merely monuments of denudation, they are the relics of elevated plateaux which have been deeply furrowed and trenched by running water and other agents of erosion. a short sketch of the leading features presented by the three divisions of the country will serve to make this plain. * * * * * the highlands.--the southern boundary of this, the most extensive of the three divisions, has already been defined. the straightness of that boundary is due to the fact that it coincides with a great line of fracture of the earth's crust--on the north or highland side of which occur slates, schists, and various other hard and tough rocks, while on the south side the prevailing strata are sandstones, etc., which are not of so durable a character. the latter, in consequence of the comparative ease with which they yield to the attacks of the eroding agents--rain and rivers, frost and ice--have been worn away to a greater extent than the former, and hence the highlands, along their southern margin, abut more or less abruptly upon the lowlands. looking across strathmore from the sidlaws or the ochils, the mountains seem to spring suddenly from the low grounds at their base, and to extend north-east and south-west, as a great wall-like rampart. the whole area north and west of this line may be said to be mountainous, its average elevation being probably not less than feet above the sea. a glance at the contoured or the shaded sheets of the ordnance survey's map of scotland will show better than any verbal description the manner in which our highland mountains are grouped. it will be at once seen that to apply the term "range" to any particular area of those high grounds is simply a misuse of terms. not only are the mountains not formed by plications and folds, but they do not even trend in linear directions. it is true that a well-trained eye can detect certain differences in the form and often in the colouring of the mountains when these are traversed from south-east to north-west. such differences correspond to changes in the composition and structure of the rock-masses, which are disposed or arranged in a series of broad belts and narrower bands, running from south-west to north-east across the whole breadth of the highlands. each particular kind of rock gives rise to a special configuration, or to certain characteristic features. thus, the mountains that occur within a belt of slate, often show a sharply cut outline, with more or less pointed peaks and somewhat serrated ridges--the aberuchill hills, near comrie, are an example. in regions of gneiss and granite the mountains are usually rounded and lumpy in form. amongst the schists, again, the outlines are generally more angular. quartz-rock often shows peaked and jagged outlines; while each variety of rock has its own particular colour, and this in certain states of the atmosphere is very marked. the mode in which the various rocks yield to the "weather"--the forms of their cliffs and corries--these and many other features strike a geologist at once; and therefore, if we are to subdivide the highland mountains into "ranges," a geological classification seems the only natural arrangement that can be followed. unfortunately, however, our geological lines, separating one belt or "range" from another, often run across the very heart of great mountain-masses. our "ranges" are distinguished from each other simply by superficial differences of feature and structure. no long parallel hollows separate a "range" of schist-mountains from the succeeding "ranges" of quartz-rock, gneiss, or granite. and no degree of careful contouring could succeed in expressing the niceties of configuration just referred to, unless the maps were on a very large scale indeed. a geological classification or grouping of the mountains into linear belts cannot therefore be shown upon any ordinary orographical map. such a map can present only the relative heights and disposition of the mountain-masses, and these last, in the case of the highlands, as we have seen, cannot be called "ranges" without straining the use of that term. any wide tract of the highlands, when viewed from a commanding position, looks like a tumbled ocean in which the waves appear to be moving in all directions. one is also impressed with the fact that the undulations of the surface, however interrupted they may be, are broad--the mountains, however they may vary in detail according to the character of the rocks, are massive, and generally round-shouldered and often somewhat flat-topped, while there is no great disparity of height amongst the dominant points of any individual group. let us take, for example, the knot of mountains between loch maree and loch torridon. there we have a cluster of eight pyramidal mountain-masses, the summits of which do not differ much in elevation. thus in liathach two points reach feet and feet; in beinn alligin there are also two points reaching feet and feet respectively; in beinn dearg we have a height of feet; in beinn eighe are three dominant points-- feet, feet, and feet. the four pyramids to the north are somewhat lower--their elevations being feet, feet, feet, and feet. the mountains of lochaber and the monadhliath mountains exhibit similar relationships; and the same holds good with all the mountain-masses of the highlands. no geologist can doubt that such relationship is the result of denudation. the mountains are monuments of erosion--they are the wreck of an old table-land--the upper surface and original inclination of which are approximately indicated by the summits of the various mountain-masses and the direction of the principal water-flows. if we in imagination fill up the valleys with the rock-material which formerly occupied their place, we shall in some measure restore the general aspect of the highland area before its mountains began to be shaped out by nature's saws and chisels. it will be observed that while streams descend from the various mountains to every point in the compass, their courses having often been determined by geological structure, etc., their waters yet tend eventually to collect and flow as large rivers in certain definite directions. these large rivers flow in the direction of the average slope of the ancient table-land, while the main water-partings that separate the more extensive drainage-areas of the country mark out, in like manner, the dominant portions of the same old land-surface. the water-parting of the north-west highlands runs nearly north and south, keeping quite close to the western shore, so that nearly all the drainage of that region flows inland. the general inclination of the north-west highlands is therefore easterly towards glenmore and the moray firth. in the region lying east of glenmore the average slopes of the land are indicated by the directions of the rivers spey, don, and tay. these two regions--the north-west and south-east highlands--are clearly separated by the remarkable depression of glenmore, which extends through loch linnhe, loch lochy, and loch ness, and the further extension of which towards the north-east is indicated by the straight coast-line of the moray firth as far as tarbat ness. now, this long depression marks a line of fracture and displacement of very great geological antiquity. the old plateau of the highlands was fissured and split in two--that portion which lay to the north-west sinking along the line of fissure to a great but at present unascertained depth. thus the waters that flowed down the slopes of the north-west portion of the broken plateau were dammed by the long wall of rock on the "up-cast," or south-east side of the fissure, and compelled to flow off to north-east and south-west along the line of breakage. the erosion thus induced sufficed in the course of time to hollow out glenmore and all the mountain-valleys that open upon it from the west. the inclination of that portion of the fissured plateau which lay to the south-east is indicated, as already remarked, by the trend of the principal rivers. it was north-east in the spey district, nearly due east in the area drained by the don, east and south-east in that traversed by the tay and its affluents, westerly and south-westerly in the district lying east of loch linnhe.[c] thus, a line drawn from ben nevis through the cairngorm and ben muich dhui mountains to kinnaird point passes through the highest land in the south-east highlands, and probably indicates approximately the dominant portion of the ancient plateau. north of that line the drainage is towards the moray firth; east of it the rivers discharge to the north sea; while an irregular winding line, drawn from ben nevis eastward through the moor of rannoch and southward to ben lomond, forms the water-parting between the north sea and the atlantic, and doubtless marks another dominant area of the old table-land. [c] the geological reader hardly requires to be reminded that many of the minor streams would have their courses determined, or greatly modified, by the geological structure of the ground. thus, such streams often flow along the "strike" and other "lines of weakness," and similar causes, doubtless, influenced the main rivers during the gradual excavation of their valleys. that the valleys which discharge their water-flow north and east to the moray firth and the north sea have been excavated by rivers and the allied agents of erosion, is sufficiently evident. all the large rivers of that wide region are typical. they show the orthodox three courses--namely, a torrential or mountain-track, a middle or valley-track, and a lower or plain-track. the same is the case with some of the rivers that flow east from the great north-and-south water-parting of the north-west highlands, as, for example, those that enter the heads of beauly firth, cromarty firth, and dornoch firth. those, however, which descend to loch lochy and loch linnhe, and the sea-lochs of argyllshire, have no lower or plain-track. when we cross the north-and-south water-parting of the north-west highlands, we find that many of the streams are destitute of even a middle or valley-track. the majority are mere mountain-torrents when they reach the sea. again, on the eastern watershed of the same region, a large number of the valleys contain lakes in their upper and middle reaches, and this is the case also with not a few of the valleys that open upon the atlantic. more frequently, however, the waters flowing west pass through no lakes, but enter the sea at the heads of long sea-lochs or fiords. this striking contrast between the east and west is not due to any difference in the origin of the valleys. the western valleys are as much the result of erosion as those of the east. the present contrast, in fact, is more apparent than real, and arises from the fact that the land area on the atlantic side has been greatly reduced in extent by subsidence. the western fiords are merely submerged land-valleys. formerly the inner and outer hebrides were united to themselves and the mainland, the country of which they formed a part stretching west into the atlantic, as far probably as the present fathoms line. were that drowned land to be re-elevated, each of the great sea-lochs would appear as a deep mountain-valley containing one or more lake-basins of precisely the same character as those that occur in so many valleys on the eastern watershed. thus we must consider all the islands lying off the west coast of the highlands, including the major portions of arran and bute, as forming part and parcel of the highland division of scotland. the presence of the sea is a mere accident; the old lands now submerged were above its level during a very recent geological period--a period well within the lifetime of the existing fauna and flora. the old table-land of which the highlands and islands are the denuded and unsubmerged relics, is of vast geological antiquity. it was certainly in existence, and had even undergone very considerable erosion, before the old red sandstone period, as is proved by the fact that large tracts of the old red sandstone formation are found occupying hollows in its surface. glenmore had already been excavated when the conglomerates of the old red sandstone began to be laid down. some of the low-lying maritime tracts of the highland area in caithness, and the borders of the moray firth, are covered with the sandstones of that age; and there is evidence to show that these strata formerly extended over wide regions, from which they have since been removed by erosion. the fact that the old red sandstone deposits still occupy such extensive areas in the north-east of the mainland, and in orkney, shows that the old table-land shelved away gradually to north and east, and the same conclusion may be drawn, as we have seen, from the direction followed by the main lines of the existing drainage-system. we see, in short, in the table-land of the highlands, one of the oldest elevated regions of europe--a region which has been again and again submerged either in whole or in part, and covered with the deposits of ancient seas and lakes, only to be re-elevated, time after time, and thus to have those deposits in large measure swept away from its surface by the long-continued action of running water and other agents of denudation. * * * * * the central lowlands.--the belt of low-lying ground that separates the highlands from the southern uplands is, as we have seen, very well defined. in many places the uplands rise along its southern margin as abruptly as the highlands in the north. the southern margin coincides, in fact, for a considerable distance (from girvan to the base of the moorfoots) with a great fracture that runs in the same direction as the bounding fracture or fault of the highlands. the central lowlands may be described, in a word, as a broad depression between two table-lands. a glance at the map will show that the principal features of the lowlands have a north-easterly trend--the same trend, in fact, as the bounding lines of the division. to this arrangement there are some exceptions, the principal being the belt of hilly ground that extends from the neighbourhood of paisley, south-east through the borders of renfrewshire and ayrshire, to the vicinity of muirkirk. the major part of the lowlands is under feet in height, but some considerable portions exceed an elevation of feet, while here and there the hills approach a height of feet--the two highest points ( and feet) being attained in ben cleugh, one of the ochils, and in tinto. probably the average elevation of the lowland division does not exceed or feet. speaking generally, the belts of hilly ground, and the more or less isolated prominences, are formed of more durable rocks than are met with in the adjacent lower-lying tracts. thus the sidlaws, the ochil hills, and the heights in renfrewshire and ayrshire, are composed chiefly of more or less hard and tough volcanic rocks; and when sandstones enter into the formation of a line of hills, as in the sidlaws, they generally owe their preservation to the presence of the volcanic rocks with which they are associated. this is well illustrated by the lomond hills in fifeshire, the basal and larger portion of which consists chiefly of somewhat soft sandstones, which have been protected from erosion by an overlying sheet of hard basalt-rock. all the isolated hills in the basin of the forth are formed of knobs, bosses, and sheets of various kinds of igneous rock, which are more durable than the sandstones, shales, and other sedimentary strata by which they are surrounded. hence it is very evident that the configuration of the lowland tracts of central scotland is due to denudation. the softer and more readily disintegrated rocks have been worn away to a greater extent than the harder and less yielding masses. only in a few cases do the slopes of the hill-belts coincide with folds of the strata. thus, the northern flanks of the sidlaws and the ochils slope towards the north-west, and this also is the general inclination of the old lavas and other rocks of which those hills are composed. the southern flanks of the same hill-belt slope in fifeshire towards the south-east--this being also the dip or inclination of the rocks. the crest of the ochils coincides, therefore, more or less closely, with an anticlinal arch or fold of the strata. but when we follow the axis of this arch towards the north-east into the sidlaws, we find it broken through by the tay valley--the axial line running down through the carse of gowrie to the north of dundee. from the fact that many similar anticlinal axes occur throughout the lowlands, which yet give rise to no corresponding features at the surface, we may conclude that the partial preservation of the anticline of the ochils and sidlaws is simply owing to the greater durability of the materials of which those hills consist. had the arch been composed of sandstones and shales it would most probably have given rise to no such prominent features as are now visible. another hilly belt, which at first sight appears to correspond roughly to an anticlinal axis, is that broad tract of igneous rocks which separates the kilmarnock coal-field from the coal-fields of the clyde basin. but although the old lavas of that hilly tract slope north-east and south-west, with the same general inclination as the surface, yet examination shows that the hills do not form a true anticline. they are built up of a great variety of ancient lavas and fragmental tuffs or "ashes," which are inclined in many different directions. in short, we have in those hills the degraded and sorely denuded fragments of an ancient volcanic bank, formed by eruptions that began upon the bottom of a shallow sea in early carboniferous times, and subsequently became sub-aërial. and there is evidence to show that after the eruptions ceased the volcanic bank was slowly submerged, and eventually buried beneath the accumulating sediments of later carboniferous times. the exposure of the ancient volcanic bank at the surface has been accomplished by the denudation of the stratified masses which formerly covered it, and its existence as a dominant elevation at the present day is solely due to the fact that it is built up of more resistant materials than occur in the adjacent low-lying areas. the ochils and the sidlaws are of greater antiquity, but have a somewhat similar history. into this, however, it is not necessary to go. the principal hills of the lowlands form two interrupted belts, extending north-east and south-west, one of them, which we may call the northern heights, facing the highlands, and the other, which may in like manner be termed the southern heights, flanking the great uplands of the south. the former of these two belts is represented by the garvock hills, lying between stonehaven and the valley of the north esk; the sidlaws, extending from the neighbourhood of montrose to the valley of the tay at perth; the ochil hills, stretching along the south side of the firth of tay to the valley of the forth at bridge-of-allan; the lennox hills, ranging from the neighbourhood of stirling to dumbarton; the kilbarchan hills, lying between greenock and ardrossan; the cumbrae islands and the southern half of arran; and the same line of heights reappears in the south end of kintyre. a well-marked hollow, trough, or undulating plain of variable width, separates these northern heights from the highlands, and may be followed all the way from near stonehaven, through strathmore, to crieff and auchterarder. between the valleys of the earn and teith this plain attains an abnormal height (the braes of doune); but from the teith, south-west by flanders moss and the lower end of loch lomond to the clyde at helensburgh, it resumes its characteristic features. it will be observed also that a hollow separates the southern portion of arran from the much loftier northern or highland area. the tract known as the braes of doune, extending from glen artney south-east to strath allan, although abutting upon the highlands, is clearly marked off from that great division by geological composition and structure, by elevation and configuration. it is simply a less deeply eroded portion of the long trough or hollow. passing now to the southern heights of the lowlands, we find that these form a still more interrupted belt than the northern heights, and that they are less clearly separated by an intermediate depression from the great uplands which they flank. they begin in the north-east with the isolated garleton hills, between which and the lammermoors a narrow low-lying trough or hollow appears. a considerable width of low ground now intervenes before we reach the pentland hills, which are in like manner separated from the southern uplands by a broad low-lying tract. at their southern extremity, however, the pentlands merge more or less gradually into a somewhat broken and interrupted group of hills which abut abruptly on the southern uplands, in the same manner as the braes of doune abut upon the slate hills of the highland borders. in this region the greatest heights reached are in tinto ( feet), and cairntable ( feet), and, at the same time, the hills broaden out towards north-west, where they are continued by the belt of volcanic rocks already described as extending between the coal-fields of the clyde and kilmarnock. although the southern heights abut so closely upon the uplands lying to the south, there is no difficulty in drawing a firm line of demarcation between the two areas--geologically and physically they are readily distinguished. no one with any eye for form, no matter how ignorant he may be of geology, can fail to see how strongly contrasted are such hills as tinto and cairntable with those of the uplands, which they face. the southern heights are again interrupted towards the south-east by the valleys of the ayr and the doon, but they reappear in the hills that extend from the heads of ayr to the valley of the girvan. betwixt the northern and southern heights spread the broad lowland tracts that drain towards the forth, together with the lower reaches of the clyde valley, and the wide moors that form the water-parting between that river and the estuary of the forth. the hills that occur within this inner region of the central lowlands are usually more or less isolated, and are invariably formed by outcrops of igneous rock. their outline and general aspect vary according to the geological character of the rocks of which they are composed--some forming more or less prominent escarpments like those of the bathgate hills and the heights behind burntisland and kinghorn, others showing a soft rounded contour like the saline hills in the west of fifeshire. of the same general character as this inner lowland region is the similar tract watered by the irvine, the ayr, and the doon. this tract, as we have seen, is separated from the larger inner region lying to the east by the volcanic hills that extend from the southern heights north-west into renfrewshire. the largest rivers that traverse the central lowlands take their rise, as might be expected, in the mountainous table-lands to the north and south. of these the principal are the north and south esks, the tay and the isla, the earn, and the forth, all of which, with numerous tributaries, descend from the highlands. and it will be observed that they have breached the line of the northern heights in three places--namely, in the neighbourhood of montrose, perth, and stirling. the only streams of importance coming north from the southern uplands are the clyde and the doon, both of which in like manner have broken through the southern heights. now, just as the main water-flows of the highlands indicate the average slope of the ancient land-surface before it was trenched and furrowed by the innumerable valleys that now intersect it, so the direction followed by the greater rivers that traverse the lowlands mark out the primeval slopes of that area. one sees at a glance, then, that the present configuration of this latter division has been brought about by the erosive action of the principal rivers and their countless affluents, aided by the sub-aërial agents generally--rain, frost, ice, etc. the hills rise above the average level of the ground, not because they have been ridged up from below, but simply owing to the more durable nature of their component rocks. that the northern and southern heights are breached only shows that the low grounds, now separating those heights from the adjacent highlands and southern uplands, formerly stood at a higher level, and so allowed the rivers to make their way more or less directly to the sea. thus, for example, the long trough of strathmore has been excavated out of sandstones, the upper surface of which once reached a much greater height, and sloped outwards from the highlands across what is now the ridge of the sidlaw hills. here then, in the central lowlands, as in the highlands, true mountain- or hill-ranges are absent. but if we are permitted to term any well-marked line or belt of high ground a "range," then the northern and southern heights of the lowlands are better entitled to be so designated than any series of mountains in the highlands. * * * * * the southern uplands.--the northern margin of this wide division having already been defined, we may now proceed to examine the distribution of its mountain-masses. before doing so, however, it may be as well to point out that considerable tracts in tweeddale, teviotdale, and liddesdale, together with the cheviot hills, do not properly belong to the southern uplands. in fact, the cheviots bear the same relation to those uplands as the northern heights do to the highlands. like them they are separated by a broad hollow from the uplands, which they face--a hollow that reaches its greatest extent in tweeddale, and rapidly wedges out to south-west, where the cheviots abut abruptly on the uplands. even where this abrupt contact takes place, however, the different configuration of the two regions would enable any geologist to separate the one set of mountains from the other. but for geographical purposes we may conveniently disregard these geological contrasts, and include within the southern uplands all the area lying between the central lowlands and the english border. if there are no mountains in the highlands so grouped and arranged as to be properly termed "ranges," this is not less true of the southern uplands. perhaps it is the appearance which those uplands present when viewed from the central lowlands that first suggested the notion that they were ranges. they seem to rise like a wall out of the low grounds at their base, and extend far as eye can reach in an approximately straight line. it seems more probable, however, that our earlier cartographers merely meant, by their conventional hill-shading, to mark out definitely the water-partings. but to do so in this manner now, when the large contour maps of the ordnance survey may be in any one's hands, is inexcusable. a study of those maps, or, better still, a visit to the tops of a few of the dominant points in the area under review, will effectually dispel the idea that the southern uplands consist of a series of ridges zigzagging across the country. like the highlands, the area of the southern uplands is simply an old table-land, furrowed into ravine and valley by the operation of the various agents of erosion. beginning our survey of these uplands in the east, we encounter first the lammermoor hills--a broad undulating plateau--the highest elevations of which do not reach feet. west of this come the moorfoot hills and the high grounds lying between the gala and the tweed--a tract which averages a somewhat higher elevation--two points exceeding feet in height. the next group of mountains we meet is that of the moffat hills, in which head a number of important rivers--the tweed, the yarrow, the ettrick, and the annan. many points in this region exceed feet, others approach feet; and some reach nearly feet, such as broad law ( feet), and dollar law ( feet). in the south-west comes the group of the lowthers, with dominant elevations of more than feet. then follow the mountain-masses in which the nith, the ken, the cree, the doon, and the girvan take their rise, many of the heights exceeding feet, and a number reaching and even passing feet, the dominant point being reached in the noble mountain-mass of the merrick ( feet). in the extreme south-west the uplands terminate in a broad undulating plateau, of which the highest point is but little over feet. all the mountain-groups now referred to are massed along the northern borders of the southern uplands. in the south-west the general surface falls more or less gradually away towards the solway--the feet contour line being reached at fifteen miles, upon an average, from the sea-coast. in the extreme north-east the high grounds descend in like manner into the rich low grounds of the merse. between these low grounds and annandale, however, the uplands merge, as it were, into the broad elevated moory tract that extends south-east, to unite with the cheviots--a belt of hills rising along the english border to heights of feet (peel fell), and feet (the cheviot). the general configuration of the main mass of the southern uplands--that is to say, the mountain-groups extending along the northern portion of the area under review, from loch ryan to the coast between dunbar and st. abb's head--is somewhat tame and monotonous. the mountains are flat-topped elevations, with broad, rounded shoulders and smooth grassy slopes. standing on the summits of the higher hills, one seems to be in the midst of a wide, gently undulating plain, the surface of which is not broken by the appearance of any isolated peaks or eminences. struggling across the bogs and peat-mosses that cover so many of those flat-topped mountains, the wanderer ever and anon suddenly finds himself on the brink of a deep green dale. he discovers, in short, that he is traversing an elevated undulating table-land, intersected by narrow and broad trench-like valleys that radiate outwards in all directions from the dominant bosses and swellings of the plateau. the mountains, therefore, are merely broad ridges and banks separating contiguous valleys; in a word, they are, like the mountains of the highlands, monuments of erosion, which do not run in linear directions, but form irregular groups and masses. the rocks that enter into the formation of this portion of the southern uplands have much the same character throughout. consequently there is less variety of contour and colour than in the highlands. the hills are not only flatter atop, but are much smoother in outline, there being a general absence of those beetling crags and precipices which are so common in the highland regions. now and again, however, the mountains assume a rougher aspect. this is especially the case with those of carrick and galloway, amongst which we encounter a wildness and grandeur which are in striking contrast to the gentle pastoral character of the lowthers and similar tracts extending along the northern and higher parts of the southern uplands. descending to details, the geologist can observe also modifications of contour even among those monotonous rounded hills. such modifications are due to differences in the character of the component rocks, but they are rarely so striking as the modifications that arise from the same cause in the highlands. to the trained eye, however, they are sufficiently manifest, and upon a geologically coloured map, which shows the various belts of rock that traverse the uplands from south-west to north-east, it will be found that the mountains occurring within each of those separate belts have certain distinctive features. such features, however, cannot be depicted upon a small orographical map. the separation of those mountains into distinct ranges, by reference to their physical aspect, is even less possible here than in the highlands. now and again, bands of certain rocks, which are of a more durable character than the other strata in their neighbourhood, give rise to pronounced ridges and banks, while hollows and valleys occasionally coincide more or less closely with the outcrops of the more readily eroded strata; but such features are mere minor details in the general configuration of the country. the courses of brooks and streams may have been frequently determined by the nature and arrangement of the rocks, but the general slope of the uplands and the direction of the main lines of water-flow are at right angles to the trend of the strata, and cannot therefore have been determined in that way. the strata generally are inclined at high angles--they occur, in short, as a series of great anticlinal arches and synclinal curves, but the tops of the grand folds have been planed off, and the axes of the synclinal troughs, so far from coinciding with valleys, very often run along the tops of the highest hills. the foldings and plications do not, in a word, produce any corresponding undulations of the surface. mention has been made of the elevated moory tracts that serve to connect the cheviots with the loftier uplands lying to north-west. the configuration of these moors is tamer even than that of the regions just described, but the same general form prevails from the neighbourhood of the moffat hills to the head-waters of the teviot. there, however, other varieties of rock appear, and produce corresponding changes in the aspect of the high grounds. not a few of the hills in this district stand out prominently. they are more or less pyramidal and conical in shape, being built up of sandstones often crowned atop with a capping of some crystalline igneous rock, such as basalt. the maiden paps, leap hill, needs law, and others are examples. the heights draining towards liddesdale and lower reaches of eskdale, composed chiefly of sandstones, with here and there intercalated sheets of harder igneous rock, frequently show escarpments and terraced outlines, but have a general undulating contour; and similar features are characteristic of the sandstone mountains that form the south-west portion of the cheviots. towards the north-east, however, the sandstones give place to various igneous rocks, so that the hills in the north-east section of the cheviots differ very much in aspect and configuration from those at the other extremity of the belt. they have a more varied and broken outline, closely resembling many parts of the ochils and other portions of the northern and southern heights of the central lowlands. the low-lying tracts of roxburghshire and the merse, in like manner, present features which are common to the inner region of the central lowlands. occasional ridges of hills rise above the general level of the land, as at smailholm and stitchell to the north of kelso, while isolated knolls and prominences--some bald and abrupt, others smooth and rounded--help to diversify the surface. bonchester hill, rubers law, the dunian, penielheugh, minto hills, and the eildons may be mentioned as examples. all of these are of igneous origin, some being mere caps of basalt resting upon a foundation of sandstone, while others are the stumps of isolated volcanoes. in the maritime tracts of galloway the low grounds repeat, on a smaller scale, the configuration of the lofty uplands behind, for they are composed of the same kinds of rock. their most remarkable feature is the heavy mountain-mass of criffel, rising near the mouth of the nith to a height of feet. everywhere, therefore, throughout the region of the southern uplands, in hilly and low-lying tracts alike, we see that the land has been modelled and contoured by the agents of erosion. we are dealing, as in the highlands, with an old table-land, in which valleys have been excavated by running water and its helpmates. nowhere do we encounter any linear banks, ridges, or ranges as we find described in the class-books, and represented upon many general maps of the country. in one of those manuals we read that in the southern district "the principal range of mountains is that known as the lowther hills, which springs off from the cheviots, and, running in a zigzag direction to the south-west, terminates on the west coast near loch ryan." this is quite true, according to many common maps, but unfortunately the "range" exists upon those maps and nowhere else. the zigzag line described is not a range of mountains, but a water-parting, which is quite another matter. the table-land of the southern uplands, like that of the highlands, is of immense antiquity. long before the old red sandstone period, it had been furrowed and trenched by running water. of the original contour of its surface, all we can say is that it formed an undulating plateau, the general slope of which was towards south-east. this is shown by the trend of the more important rivers, such as the nith and the annan, the gala and the leader; and by the distribution of the various strata pertaining to the old red sandstone and later geological periods. thus, strata of old red sandstone and carboniferous age occupy the merse and the lower reaches of teviotdale, and extend up the valleys of the whiteadder and the leader into the heart of the silurian uplands. in like manner permian sandstones are well developed in the ancient hollows of annandale and nithsdale. along the northern borders of the southern uplands we meet with similar evidence to show that even as early as old red sandstone times the old plateau, along what is now its northern margin, was penetrated by valleys that drained towards the north. the main drainage, however, then as now, was directed towards south-east. many geological facts conspire to show that the silurian table-land of these uplands has been submerged, like the highlands, in whole or in part. this happened at various periods, and each time the land went down it received a covering of newer accumulations--patches of which still remain to testify to the former extent of the submergences. from the higher portions of the uplands those accumulations have been almost wholly swept away, but they have not been entirely cleared out of the ancient valleys. they still mantle the borders of the silurian area, particularly in the north-east, where they attain a great thickness in the moors of liddesdale and the cheviot hills. the details of the evolution of the whole area of the southern uplands form an interesting study, but this pertains rather to geology than to physical geography. it is enough, from our present point of view, to be assured that the main features of the country were chalked out, as it were, at a very distant geological period, and that all the infinite variety in the relief of our land has been brought about directly, not by titanic convulsions and earth-movements, but by the long-continued working of rain and rivers--of frost and snow and ice, supplemented from time to time by the action of the sea. the physical features more particularly referred to in this paper are of course only the bolder and more prominent contours--those namely which can be expressed with sufficient accuracy upon sheets of such a size as the accompanying orographical map of scotland (plate i.). with larger maps considerably more detail can be added, and many characteristic and distinguishing features will appear according to the care with which such maps are drawn. in the case of the ordnance survey map, on the scale of inch to a mile, the varying forms of the surface are so faithfully delineated as frequently to indicate to a trained observer the nature of the rocks and the geological structure of the ground. the artists who sketched the hills must indeed have had good eyes for form. so carefully has their work been done, that it is often not difficult to distinguish upon their maps hills formed of such rocks as sandstone from those that are composed of more durable kinds. the individual characteristics of mountains of schist, of granite, of quartz-rock, of slate, are often well depicted: nay, even the varieties of igneous rock which enter into the formation of the numerous hills and knolls of the lowlands can frequently be detected by the features which the artists have so intelligently caught. another set of features which their maps display are those due to glaciation. these are admirably brought out, even down to the smallest details. a glance at such maps as those of teviotdale and the merse, for example, shows at once the direction taken by the old _mer de glace_. the long parallel flutings of the hill-slopes, _roches moutonnées_, projecting knolls and hills with their "tails," the great series of banks and ridges of stony clay which trend down the valley of the tweed--these, and many more details of interest to specialists, are shown upon the maps. all over scotland similar phenomena are common, and have been reproduced with marvellous skill on the shaded sheets issued by the ordnance survey. and yet the artists were not geologists. the present writer is glad of this opportunity of recording his obligations to those gentlemen. their faithful delineations of physical features have given him many valuable suggestions, and have led up to certain observations which might otherwise not have been made. iii. mountains: their origin, growth, and decay.[d] [d] _scottish geographical magazine_, vol. ii., . mountains have long had a fascination for lovers of nature. time was, however, when most civilised folk looked upon them with feelings akin to horror; and good people, indeed, have written books to show that they are the cursed places of the earth--the ruin and desolation of their gorges and defiles affording indubitable proof of the evils which befell the world when man lapsed from his primitive state of innocence and purity. all this has changed. it is the fashion now to offer a kind of worship to mountains; and every year their solitudes are invaded by devotees--some, according to worthy meg dods, "rinning up hill and down dale, knapping the chuckie-stanes to pieces wi' hammers, like sae mony roadmakers run daft--to see, as they say, how the warld was made"--others trying to transfer some of the beauty around them to paper or canvas--yet others, and these perhaps not the least wise, content, as old sir thomas browne has it, "to stare about with a gross rusticity," and humbly thankful that they are beyond the reach of telegrams, and see nothing to remind them of the _fumun et opes strepitumque romæ_. but if the sentiment with which mountains are regarded has greatly changed, so likewise have the views of scientific men as to their origin and history. years ago no one doubted that all mountains were simply the result of titanic convulsions. the crust of the earth had been pushed up from below, tossed into great billows, shivered and shattered--the mountains corresponding to the crests of huge earth-waves, the valleys to the intervening depressions, or to gaping fractures and dislocations. this view of the origin of mountains has always appeared reasonable to those who do not know what is meant by geological structure, and in some cases it is pretty near the truth. a true mountain-chain, like that of the alps, does indeed owe its origin to gigantic disturbances of the earth's crust, and in such a region the larger features of the surface often correspond more or less closely with the inclination of the underlying rocks. but in many elevated tracts, composed of highly disturbed and convoluted strata, no such coincidence of surface-features and underground structure can be traced. the mountains do not correspond to great swellings of the crust--the valleys neither lie in trough-shaped strata, nor do they coincide with gaping fractures. again, many considerable mountains are built up of rocks which have not been convoluted at all, but occur in approximately horizontal beds. evidently, therefore, some force other than subterranean action must be called upon to explain the origin of many of the most striking surface-features of the land. every geologist admits--it is one of the truisms of his science--that corrugations and plications are the result of subterranean action. nor does any one deny that when a true mountain-chain was first upheaved the greater undulations of the folded strata probably gave rise to similar undulations at the surface. some of the larger fractures and dislocations might also have appeared at the surface and produced mural precipices. so long a time, however, has elapsed since the elevation of even the youngest mountain-chains of the globe that the sub-aërial agents of erosion--rain, frost, rivers, glaciers, etc.--have been enabled greatly to modify their primeval features. for these mountains, therefore, it is only partially true that their present slopes coincide with those of the underlying strata. such being the case with so young a chain as the alps, we need not be surprised to meet with modifications on a still grander scale in mountain-regions of much greater antiquity. in many such tracts the primeval configuration due to subterranean action has been entirely remodelled, so that hills now stand where deep hollows formerly existed, while valleys frequently have replaced mountains. and this newer configuration is the direct result of erosion, guided by the mineralogical composition and structural peculiarities of the rocks. it is difficult, or even impossible, for one who is ignorant of geological structure to realise that the apparently insignificant agents of erosion have played so important a _rôle_ in the evolution of notable earth-features. it may be well, therefore, to illustrate the matter by reference to one or two regions where the geological structure is too simple to be misunderstood. the first examples i shall give are from tracts of horizontal strata. many readers are doubtless aware of the fact that our rock-masses consist for the most part of the more or less indurated and compacted sediments of former rivers, lakes, and seas. frequently those ancient water-formed rocks have been very much altered, so as even sometimes to acquire a crystalline character. but it is enough for us now to remember that the crust of the globe, so far as that is accessible to observation, is built up mostly of rocks which were originally accumulated as aqueous sediments. such being the case, it is obvious that our strata of sandstone, conglomerate, shale, limestone, etc., must at first have been spread out in approximately horizontal or gently inclined sheets or layers. we judge so from what we know of sediments which are accumulating at present. the wide flats of our river valleys, the broad plains that occupy the sites of silted-up lakes, the extensive deltas of such rivers as the nile and the po, the narrow and wide belts of low-lying land which within a recent period have been gained from the sea, are all made up of various kinds of sediment arranged in approximately horizontal layers. now, over wide regions of the earth's surface the sedimentary strata still lie horizontally, and we can often tell at what geological period they became converted into dry land. thus, for example, we know that the elevated plateau through which the river colorado flows is built up of a great series of nearly horizontal beds of various sedimentary deposits, which reach a thickness of many thousand feet. it is self-evident that the youngest strata must be those which occur at the surface of the plateau, and they, as we know, are of lacustrine origin and belong to the tertiary period. now, american geologists have shown that since that period several thousands of feet of rock-materials have been removed from the surface of that plateau--the thickness of rock so carried away amounting in some places to nearly , feet. yet all that prodigious erosion has been effected since early tertiary times. indeed, it can be proved that the excavation of the grand cañon of the colorado, probably the most remarkable river-trench in the world, has been accomplished since the close of the tertiary period, and is therefore a work of more recent date than the last great upheaval of the swiss alps. the origin of the cañon is self-evident--it is a magnificent example of river-erosion, and the mere statement of its dimensions gives one a forcible impression of the potency of sub-aërial denudation. the river-cutting is about miles long, or miles broad, and varies from to feet in depth. take another example of what denuding agents have done within a recent geological period. the faröe islands, some twenty in number, extend over an area measuring about miles from south to north, and nearly miles from west to east. these islands are composed of volcanic rocks--beds of basalt with intervening layers of fine fragmental materials, and are obviously the relics of what formerly was one continuous plateau, deeply trenched by valleys running in various directions. subsequent depression of the land introduced the sea to these valleys, and the plateau was then converted into a group of islands, separated from each other by narrow sounds and fiords. were the great plateau through which the colorado flows to be partially submerged, it would reproduce on a larger scale the general phenomena presented by this lonely island-group of the north atlantic. the flat-topped "buttes" and "mesas," and the pyramidal mountains of the colorado district would form islands comparable to those of the faröes. most of the latter attain a considerable elevation above the sea--heights of , , , and feet being met with in several of the islands. indeed, the average elevation of the land in this northern archipelago can hardly be less than feet. the deep trench-like valleys are evidently only the upper reaches of valleys which began to be excavated when the islands formed part and parcel of one and the same plateau--the lower reaches being now occupied by fiords and sounds. it is quite certain that all these valleys are the work of erosion. one can trace the beds of basalt continuously across the bottoms, and be quite sure that the valleys are not gaping cracks or fractures. now, as the strata are approximately horizontal, it is obvious that the hollows of the surface have nothing whatever to do with undulations produced by earth-movements. the sub-aërial erosion of the islands has resulted in the development of massive flat-topped and pyramidal mountains. these stand up as eminences simply because the rock-material which once surrounded them has been gradually broken up and carried away. nothing can well be more impressive to the student of physical geology than the aspect presented by these relics of an ancient plateau (plate ii. fig. ). standing on some commanding elevation, such as nakkin in suderöe, one sees rising before him great truncated pyramids--built up of horizontal beds of basalt rising tier above tier--the mountains being separated from each other by wide and profound hollows, across which the basalt-beds were once continuous. owing to the parallel and undisturbed position of the strata, it is not hard to form an estimate of the amount of material which has been removed during the gradual excavation of the valleys. in order to do so we have simply to measure the width, depth, and length of the valleys. thus in suderöe, which is miles long and miles broad, the bottoms of the valleys are feet at least below the tops of the mountains, and some of the hollows in question are a mile in width. now, the amount of rock worn away from this one little island by sub-aërial erosion cannot be less than that of a mass measuring miles in length by miles in breadth, and feet in thickness. and yet the faröe islands are composed of rocks which had no existence when the soft clays, etc., of the london basin were being accumulated. all the erosion referred to has taken place since the great upheaval of the eocene strata of the swiss alps. but if the evidence of erosion be so conspicuous in regions composed of horizontal strata, it is not less so in countries where the rocks are inclined at various angles to the horizon. indeed, the very fact that inclined strata crop out at the surface is sufficient evidence of erosion. for it is obvious that these outcrops are merely the truncated ends of beds which must formerly have had a wider extension. but while the effects produced by the erosion of horizontal strata are readily perceived by the least-informed observer, it requires some knowledge of geological structure to appreciate the denudation of curved or undulating strata. and yet there is really no mystery in the matter. all we have to do is by careful observation to ascertain the mode of arrangement of the rocks--this accomplished, we have no difficulty in estimating the minimum erosion which any set of strata may have experienced. an illustration may serve to make this plain. here, for example, is a section across a region of undulating strata (fig. ). let the line _a b_ represent the surface of the ground, and _c d_ be any datum line--say, the sea-level. an observer at _a_, who should walk in the direction of _b_, would cross successively eight outcrops of coal; and, were he incapable of reading the geological structure of the ground, he might imagine that he had come upon eight separate coal-seams. a glance at the section, however, shows that in reality he had met with only two coals, and that the deceptive appearances, which might be misread by an incautious observer, are simply the result of denudation. in this case the tops of a series of curved or arched beds have been removed (as at _e_), and, by protracting the lines of the truncated beds until they meet, we can estimate the minimum amount of erosion they have sustained. thus, if the strata between _o_ and _p_ be feet thick, it is self-evident that a somewhat greater thickness of rock must have been removed from the top of the anticlinal arch or "saddleback" at _e_. again, let us draw a section across strata which have been fractured and dislocated, and we shall see how such fractures likewise enable us to estimate the minimum amount of erosion which certain regions have experienced. in fig. we have a series of strata containing a bed of limestone _l_, and a coal-seam _a_. the present surface of the ground is represented by the line _a b_. at _f_ the strata are traversed by a fault or dislocation--the beds being thrown down for say feet on the low side of the fault--so that the coal at _a^ _ occurs now at a depth of feet below its continuation at _a^ _. at the surface of the ground there is no inequality of level--the beds overlying the coal (_a²_) having been removed by denudation. were the missing rocks to be replaced, they would occupy the space contained within the dotted lines above the present surface _a b_. such dislocations are of common occurrence in our coal-fields, and it is not often that they give rise to any features at the surface. we may thus traverse many level or gently-undulating tracts, and be quite unconscious of the fact that geologically we have frequently leaped up or dropped down for hundreds of feet in a single step. nay, some scottish streams and rivers flow across dislocations by which the strata have been shifted up or down for thousands of feet, and in some places one can have the satisfaction of sitting upon rocks which are geologically yards below or above those on which he rests his feet. in other words, thousands of feet of strata have been removed by denudation from the high sides of faults. these, as i have said, often give rise to no feature at the surface; but, occasionally, when "soft" rocks have been shifted by dislocations, and brought against "hard" rocks, the latter, by better resisting denudation than the former, cause a more or less well-marked feature at the surface, and thus betray the presence of a fault to the geologist. the phenomena presented by faults, therefore, are just as eloquent of denudation as is the truncated appearance of our strata; and only after we have carefully examined the present extension and mutual relations of our rock-masses, their varied inclination, and the size of the dislocations by which they are traversed, can we properly appreciate the degree of erosion which they have sustained. before we are entitled to express any opinion as to the origin of the surface-features of a country, we must first know its geological structure. until we have attained such knowledge, all our views as to the origin of mountains are of less value than the paper they are written upon. i have spoken of the evidence of denudation which we find in our truncated and dislocated rock-masses; there is yet another line of evidence which i may very shortly point out. as every one knows, there exist in this and many other countries enormous masses of igneous rocks, which have certainly been extruded from below. now, some of these rocks, such as granite, belong to what is called the _plutonic_ class of rocks; they are of deep-seated origin--that is to say, they never were erupted at the surface, but cooled and consolidated at great depths in the earth's crust. i need not go into any detail to show that this is the case--it is a conclusion based upon incontrovertible facts, and accepted by every practical geologist. when, therefore, we encounter at the actual surface of the earth great mountain-masses of granite, we know that in such regions enormous denudation has taken place. the granite appears at the surface simply because the thick rock-masses under which it solidified have been gradually removed by erosion. the facts which i have now briefly passed in review must convince us that erosion is one of the most potent factors with which the geologist has to deal. we have seen what it has been able to effect in certain tracts composed of strata which date back to a recent geological period, such as the plateau of the colorado and the pyramidal mountains of the faröe islands. if in regions built up of strata so young as the rocks of those tracts the amount of erosion be so great, we may well expect to meet with evidence of much more extensive denudation in regions which have been subjected for enormously longer periods to the action of the eroding agents. the study of geological structure, or the architecture of the earth's crust, has enabled us to group all mountains under these three principal heads:-- . _mountains of accumulation._ . _mountains of elevation._ . _mountains of circumdenudation._ . mountains of accumulation.--volcanoes may be taken as the type of this class of mountains. these are, of course, formed by the accumulation of igneous materials around the focus or foci of eruption, and their mode of origin is so generally understood, and, indeed, so obvious, that i need do no more than mention them. of course, they are all subject to erosion, and many long-extinct volcanoes are highly denuded. some very ancient ones, as those of our own country, have been so demolished that frequently all that remains are the now plugged-up pipes or flues through which the heated materials found a passage to the surface--all those materials, consisting of lavas and ashes, having in many cases entirely disappeared. in former times volcanic eruptions often took place along the line of an extensive fissure--the lava, instead of being extruded at one or more points, welled-up and overflowed along the whole length of the fissure, so as to flood the surrounding regions. and this happening again and again, vast plateaux of igneous rock came to be built up, such as those of the rocky mountains, iceland, the faröes, antrim and mull, abyssinia and the deccan. these are called _plateaux of accumulation_ (see fig. ), and all of them are more or less highly denuded, so that in many cases the plateaux have quite a mountainous appearance. of course, plateaux of accumulation are not always formed of igneous rocks. any area of approximately horizontal strata of aqueous origin, rising to a height of a thousand feet or more above the sea, would come under this class of plateau--the plateau of the colorado being a good example. although that plateau is of recent origin, yet its surface, as we have seen, has been profoundly modified by superficial erosion; and this is true to a greater extent of plateaux which have been much longer exposed to denudation. it is obvious that even mountains and plateaux of accumulation often owe many of their present features to the action of the surface-agents of change. . mountains of elevation.--we have seen that the strata which enter most largely into the composition of the earth's crust, so far as that is open to observation, consist of rocks which must originally have been disposed in horizontal or approximately horizontal layers. but, as every one knows, the stratified rocks are not always horizontally arranged. in scotland they rarely are so. on the contrary, they are inclined at all angles from the horizon, and not infrequently they even stand on end. moreover, they are often traversed by dislocations, large and small. no one doubts that these tilted and disturbed rocks are evidence of wide-spread earth-movements. and it has been long known to geologists that such movements have happened again and again in this and many other countries where similar disturbed strata occur. some of these movements, resulting in the upheaval of enormous mountain-masses, have taken place within comparatively recent geological times. others again date back to periods inconceivably remote. the pyrenees, the alps, the caucasus, the himalaya, which form the back-bone of eurasia, are among the youngest mountains of the globe. the highlands of scotland and scandinavia are immeasurably more ancient; they are, in point of fact, the oldest high grounds in europe, nor are there any mountain-masses elsewhere which can be shown to be older. but while the alps and other recent mountains of elevation still retain much of their original configuration, not a vestige of the primeval configuration of our own highlands has been preserved; their present surface-features have no direct connection with those which must have distinguished them in late silurian times. our existing mountains are not, like those of the alps, mountains of elevation. the structure of a true mountain-chain is frequently very complicated, but the general phenomena can be readily expressed in a simple diagram. let fig. be a section taken across a mountain-chain, _i.e._ at right angles to its trend or direction. the dominant point of the chain is shown at _b_, while _a_ and _c_ represent the low grounds. now, an observer at _a_, advancing towards _b_, would note that the strata, at first horizontal, would gradually become undulating as he proceeded on his way--the undulations getting always more and more pronounced. he would observe, moreover, that the undulations, at first symmetrical, as at _a_, would become less so as he advanced--one limb of an arch or _anticline_, as it is termed, being inclined at a greater angle than the other, as at _b_. approaching still nearer to =b=, the arches or anticlines would be seen eventually to bend over upon each other, so as to produce a general dip or inclination of the strata towards the central axis of the chain. crossing that axis (_b_), and walking in the direction of the low grounds (_c_), the observer would again encounter the same structural arrangement, but of course in reverse order. thus, in its simplest expression, a true mountain-chain consists of strata arranged in a series of parallel undulations--the greater mountain ridges and intervening hollows corresponding more or less closely to the larger undulations and folds of the strata. now, could these plicated strata be pulled out, could the folds and reduplications be smoothed away, so as to cause the strata to assume their original horizontal position, it is obvious that the rocks would occupy a greater superficial area. we see, then, that such a mountain-chain must owe its origin to a process of tangential or lateral thrusting and crushing. the originally horizontal strata have been squeezed laterally, and have yielded to the force acting upon them by folding and doubling up. it seems most probable that the larger contortions and foldings which are visible in all true mountain-chains, owe their origin to the sinking down of the earth's crust upon the cooling and contracting nucleus. during such depressions of the crust the strata are necessarily subjected to enormous lateral compression; they are forced to occupy less space at the surface, and this they can only do by folding and doubling-back upon themselves. if the strata are equally unyielding throughout a wide area, then general undulation may ensue; but should they yield unequally, then folding and contortion will take place along one or more lines of weakness. in other words, the pressure will be relieved by the formation of true mountain-chains. thus, paradoxical as it may seem, the loftiest mountains of the globe bear witness to profound depression or subsidence of the crust. the andes, for example, appear to owe their origin to the sinking down of the earth's crust under the pacific; and so in like manner the alps would seem to have been ridged up by depression of the crust in the area of the mediterranean. mountain-chains, therefore, are true wrinkles in the crust of the earth; they are lines of weakness along which the strata have yielded to enormous lateral pressure. a glance at the geological structure of the alps and the jura shows us that these mountains are a typical example of such a chain; they are mountains of elevation. in the jura the mountains form a series of long parallel ridges separated by intervening hollows; and the form or shape of the ground coincides in a striking manner with the foldings of the strata. in these mountains we see a succession of symmetrical flexures, the beds dipping in opposite directions at the same angle from the axis of each individual anticline. there each mountain-ridge corresponds to an _anticline_, and each valley to a _syncline_, or trough-shaped arrangement of strata. but as we approach the alps the flexures become less and less symmetrical, until in the alps themselves the most extraordinary convolutions and intricate plications appear, the strata being often reversed or turned completely upside down. though it is true that the slopes of this great mountain-chain not infrequently correspond more or less closely to the slope or inclination of the underlying rocks, it must not be supposed that this correspondence is often complete. sometimes, indeed, we find that the mountains, so far from coinciding with anticlines, are in reality built up of synclinal or basin-shaped strata; while in other cases deep and broad valleys run along the lines of anticlinal axes (fig. ). all this speaks to enormous erosion. a study of the geological structure of the alps demonstrates that thousands of feet of rock have been removed from those mountains since the time of their elevation. a section drawn across any part of the chain would show that the strata have been eroded to such an extent, and the whole configuration so profoundly modified, that it is often difficult, or even impossible, to tell what may have been the original form of the surface when the chain was upheaved. and yet the alps, it must be remembered, are of comparatively recent age, some of their highly-confused and contorted rocks consisting of marine strata which are of no greater antiquity than the incoherent clays and sands of the london tertiary basin. now, when we reflect upon the fact that, in the case of so young a mountain-chain, the configuration due to undulations of the strata has been so greatly modified, and even in many places obliterated, it is not hard to believe that after sufficient time has elapsed--after the alps have existed for as long a period, say, as the mountains of middle germany--every mountain formed of anticlinal strata shall have disappeared, and those synclines which now coincide with valleys shall have developed into hills. the reader who may have paid little or no attention to geological structure and its influence upon the form of the ground, will probably think this a strange and extravagant statement; yet i hope to show presently that it is supported by all that we know of regions of folded strata which have been for long periods of time subjected to denudation. * * * * * . mountains of circumdenudation.--in countries composed of undulating and folded strata which have been for long ages exposed to the action of eroding agents, the ultimate form assumed by the ground is directly dependent on the character of the rocks, and the mode of their arrangement. the various rock-masses which occur in such a neighbourhood as edinburgh, for example, differ considerably in their power of resisting denudation. hence the less readily eroded rocks have come in time to form hills of less or greater prominence. such is the case with the castle rock, corstorphine hill, the braids, the pentlands, etc. these hills owe their existence, as such, to the fact that they are composed of more enduring kinds of rock than the softer sandstones and shales by which they are surrounded, and underneath which they were formerly buried to great depths. some hills, again, which are for the most part built up of rocks having the same character as the strata that occur in the adjacent low grounds, stand up as prominences simply because they have been preserved by overlying caps or coverings of harder rocks--rocks which have offered a stronger resistance to the action of the denuding agents. the lomond hills are good examples. those hills consist chiefly of sandstones which have been preserved from demolition by an overlying sheet of basalt-rock. but the mode in which rocks are arranged is a not less important factor in determining the shape which the ground assumes under the action of the agents of erosion. thus, as we have already seen, flat-topped, pyramidal mountains, and more or less steep-sided or trench-like valleys, are characteristic features in regions of horizontal strata. when strata dip or incline in one general direction, then we have a succession of escarpments or dip-slopes, corresponding to the outcrops of harder or less readily eroded beds, and separated from each other by long valleys, hollows, or undulating plains, which have the same trend as the escarpments (fig. ). this kind of configuration is well exemplified over a large part of england. the general dip or inclination of the mesozoic or secondary strata throughout that country, between the shores of the north sea and the english channel, is easterly and south-easterly--so that the outcrops of the more durable strata form well-defined escarpments that face the west and north-west, and can be followed almost continuously from north to south. passing from the malvern hills in a south-easterly direction, we traverse two great escarpments--the first coinciding with the outcrop of the oolite, and forming the cotswold hills; and the second corresponding to the outcrop of the chalk, and forming the chiltern hills. the plains and low undulating tracts that separate these escarpments mark the outcrops of more yielding strata--the low grounds that intervene between the cotswolds and the malvern hills being composed of liassic and triassic clays and sandstones. in scotland similar escarpments occur, but owing to sudden changes of the dip, and various interruptions of the strata, the scottish escarpments are not so continuous as those of the sister-country. many of the belts of hilly ground in the scottish lowlands, however, exemplify the phenomena of escarpment and dip-slope. thus, the sidlaws in forfarshire consist of a series of hard igneous rocks and interbedded sandstones and flags--the outcrops of which form a succession of escarpments with intervening hollows. the same appearances recur again and again all over the lowlands. wherever, indeed, any considerable bed of hard rock occurs in a series of less enduring strata--the outcrop of the harder rock invariably forms a well-marked feature or escarpment. as examples, i may refer to salisbury crags, craiglockhart hill, dalmahoy crags, the bathgate hills, king alexander's crag, etc. all these are conspicuous examples of the work of denudation--for it can be demonstrated that each of these rock-masses was at one time deeply buried under sandstones and shales, and they now crop out at the surface, and form prominent features simply because the beds which formerly covered and surrounded them have been gradually removed. from what has now been said it will be readily understood that in regions composed of strata the inclination or dip of which is not constant but continually changing in direction, the surface-features must be more or less irregular. if the strata dip east the outcrops of the harder beds will form escarpments facing the west, and the direction of the escarpments will obviously change with the direction of the dip. undulating strata of variable composition will, in short, give rise to an undulating surface, but the superficial undulations will not coincide with those of the strata. on the contrary, in regions consisting of undulating strata of diverse consistency the hills generally correspond with synclinal troughs--or, in other words, trough-shaped strata tend to form hills; while, on the other hand, arch-shaped or anticlinal strata most usually give rise to hollows (see fig. ). this remarkable fact is one of the first to arrest the attention of every student of physical geology, and its explanation is simple enough. an anticlinal arrangement of strata is a weak structure--it readily succumbs to the attacks of the denuding agents; a synclinal arrangement on the contrary, is a strong structure, which is much less readily broken up. hence it is that in all regions which have been exposed for prolonged periods to sub-aërial denudation synclinal strata naturally come to form hills, and anticlinal strata valleys or low grounds. in the case of a mountain-chain so recently elevated as that of the alps, the mountain-ridges, as we have seen, often coincide roughly with the greater folds of the strata. such anticlinal mountains are weakly built, and consequently rock-falls and landslips are of common occurrence among them--far more common, and on a much larger scale, than among the immeasurably older mountains of scandinavia and scotland. the valleys of the pyrenees, the alps, and the apennines, are cumbered with enormous chaotic heaps of fallen rock-masses. from time to time peaks and whole mountain-sides give way, and slide into the valleys, burying hamlets and villages, and covering wide tracts of cultivated land. hundreds of such disastrous rock-falls have occurred in the alps within historical ages, and must continue to take place until every weakly-formed mountain has been demolished. the hills and mountains of scotland have long since passed through this phase of unstable equilibrium. after countless ages of erosion our higher grounds have acquired a configuration essentially different from that of a true mountain-chain. enormous landslips like that of the rossberg are here impossible, for all such weakly-constructed mountains have disappeared. a little consideration will serve to show how such modifications and changes have come about. when strata are crumpled up they naturally crack across, for they are not elastic. during the great movements which have originated all mountains of elevation, it is evident that the strata forming the actual surface of the ground would often be greatly fissured and shattered along the crests of the sharper anticlinal ridges. in the synclinal troughs, however, although much fissuring would take place, yet the strata would be compelled by the pressure to keep together. now, when we study the structure of such a region as the alps, we find that the tops of the anticlines have almost invariably been removed, so as to expose the truncated ends of the strata--the ruptured and shattered rock-masses having in the course of time been carried away by the agents of erosion. such mountains are pre-eminently weak structures. let us suppose that the mountains represented in the diagram (fig. ) consist of a succession of strata, some of which are more or less permeable by water, while others are practically impermeable. it is obvious that water soaking down from the surface will find its way through the porous strata (_p_), and come out on the slopes of the mountains along the joints and cracks (_c_) by which all strata are traversed. under the influence of such springs and the action of frost, the rock at the surface will eventually be broken up, and ever and anon larger and smaller portions will slide downwards over the surface of the underlying impermeable stratum. the undermining action of rivers will greatly intensify this disintegrating and disrupting process. as the river deepens and widens its valley (_v_), it is apparent that in doing so it must truncate the strata that are inclined towards it. the beds will then crop out upon the slopes of the valley (as at _b_, _b_), and so the conditions most favourable for a landslip will arise. underground water, percolating through the porous beds (p), and over the surface of the underlying impermeable beds (_i_, _i_, _i_), must eventually bring about a collapse. the rocks forming the surface-slopes of the mountain will from time to time give and slide into the valley, or the whole thickness of the truncated strata may break away and rush downwards; and this process must continue so long as any portion of the anticlinal arch remains above the level of the adjacent synclinal troughs. thus it will be seen that an anticlinal arch is a weak structure--a mountain so constructed falls a ready prey to the denuding agents; and hence in regions which have been exposed to denudation for as long a period as the scottish or scandinavian uplands, a mountain formed of anticlinally arranged strata is of very exceptional occurrence. when it does appear, it is only because the rocks of which it is composed happen to be of a more enduring character than those of the adjacent tracts. the ochil hills exemplify this point. these hills consist of a great series of hard igneous rocks, which are arranged in the form of a depressed anticlinal arch--the low grounds lying to the north and south being composed chiefly of sandstones and shales. here it is owing to the more enduring character of the igneous rocks that the anticlinal arch has not been entirely removed. we know, however, that these igneous rocks were formerly buried under a great thickness of strata, and that their present appearance at the surface is simply the result of denudation. if an anticlinal arch be a weak structure, a synclinal arrangement of strata is quite the opposite. in the case of the former each bed has a tendency to slip or slide away from the axis, while in a syncline it is just the reverse--the strata being inclined towards and not away from the axis. underground water, springs, and frost are enabled to play havoc with anticlinal strata, for the structure is entirely in their favour. but in synclinal beds the action of these powerful agents is opposed by the structure of the rocks--and great rock-falls and landslips cannot take place. synclinal strata therefore endure, while anticlinal strata are worn more readily away. even in a true mountain-range so young as the alps, denudation has already demolished many weakly-built anticlinal mountains, and opened up valleys along their axes; while, on the other hand, synclinal troughs have been converted into mountains. and if this be true of the alps, it is still more so of much older mountain-regions, in which the original contours due to convolutions of the strata have entirely disappeared (see fig. ). the mountains of such regions, having been carved out and modelled by denuding agents, are rightly termed _mountains of circumdenudation_, for they are just as much the work of erosion as the flat-topped and pyramidal mountains which have been carved out of horizontal strata. the scottish highlands afford us an admirable example of a mountainous region of undulating and often highly-flexed strata, in which the present surface-features are the result of long-continued erosion. as already remarked, this region is one of the oldest land-surfaces in the world. in comparison with it, the pyrenees, the alps, and the himalayas are creations of yesterday. the original surface or configuration assumed by the rocks composing our highland area at the time when these were first crushed and folded into anticlines and synclines had already been demolished at a period inconceivably more remote than the latest grand upheaval of the alps. even before the commencement of old red sandstone times, our archæan, cambrian, and silurian rocks had been planed down for thousands of feet, so that the bottom beds of the old red sandstone were deposited upon a gently undulating surface, which cuts across anticlines and synclines alike. in late silurian and early post-silurian times the north-west highlands probably existed as a true mountain-chain, consisting of a series of parallel ranges formed by the folding and reduplication of the strata. the recent observations of my friends, professor lapworth and messrs. peach and horne, in sutherland, have brought to light the evidence of gigantic earth-movements, by which enormous masses of strata have been convoluted and pushed for miles out of place. we see in that region part of a dissected mountain-chain. the mountain-masses which are there exposed to view are the basal or lower portions of enormous sheets of disrupted rock, the upper parts of which have been removed by denudation. in a word, the mountains of sutherland are mountains of circumdenudation--they have been carved out of elevated masses by the long-continued action of erosion. to prove this, one has only to draw an accurate section across the north-west highlands, when it becomes apparent that the form or shape of the ground does not correspond or coincide with the convolutions of the strata, and that a thickness of thousands of feet of rock has been denuded away since those strata were folded and fractured. all over the highlands we meet with similar evidence of enormous denudation. the great masses of granite which appear at the surface in many places are eloquent of the result produced by erosion continued for immeasurable periods of time. every geologist knows that granite is a rock which could only have been formed and consolidated at great depths. when, therefore, such a rock occurs at the surface, it is evidence beyond all doubt of prodigious erosion. the granite has been laid bare by the removal of the thick rock-masses underneath which it cooled and consolidated. a glance at any map of scotland will show that many river-valleys, and not a few lakes, of the highlands have a north-east and south-west trend. this trend corresponds to what geologists call the _strike_ of the strata. the rocks of the highlands have been compressed into a series of folds or anticlines and synclines, which have the direction just stated--namely, north-east and south-west. a careless observer might therefore rashly conclude that these surface-features resembled those of the jura--in other words, that the long parallel hollows were synclinal troughs, and that the intervening ridges and high grounds were anticlinal arches or saddle-backs. nothing could be further from the truth. a geological examination of the ground would show that the features in question were everywhere the result of denudation, guided by the petrological character and geological structure of the rocks. several of the most marked hollows run along the backs of anticlinal axes, while some of the most conspicuous mountains are built up of synclinal or trough-shaped strata. ben lawers, and the depression occupied by loch tay, are excellent examples; and since that district has recently been mapped in detail by mr. j. grant wilson, of the geological survey, i shall give a section (fig. ) to show the relation between the form of the ground and the geological structure of the rocks. this section speaks for itself. here evidently is a case where "valleys have been exalted and mountains made low." a well-marked syncline, it will be observed, passes through ben lawers, while loch tay occupies a depression scooped out of an equally well-defined anticline--a structure which is just the opposite of that which we should expect to find in a true mountain-chain. it will be also noted that glen-lyon coincides neither with a syncline nor a fault; it has been eroded along the outcrops of the strata. many of the north-east and south-west hollows of the highlands indeed run along the base of what are really great escarpments--a feature which, as we have seen, is constantly met with in every region where the strata "strike" more or less steadily in one direction. in the highlands the strata are most frequently inclined at considerable angles, so that the escarpments succeed each other more rapidly than would be the case if the strata were less steeply inclined. in no case does any north-east and south-west hollow coincide with a structural cavity. loch awe has been cited as an example of a superficial depression formed by the inward dip of the strata on either side. but, as was shown many years ago by my brother, a. geikie,[e] this lake winds across the _strike_ of the strata. moreover, if it owed its existence to a great synclinal fold, why, he asks, does it not run along the same line as far as the same structure continues? it does not do so: it is not continuous with the synclinal fold, while vertical strata appear in the middle of the lake, where, as my brother remarks, they have clearly no business to be if the sides of the lake are formed by the inward dip of the schists. [e] _trans. edin. geol. soc._ vol. ii. p. . the great glen, as i mentioned in the preceding article, coincides with a fracture or dislocation--a line of weakness along which the denuding agents had worked for many ages before the beginning of old red sandstone times; and it is possible that smaller dislocations may yet be detected in other valleys. but in each and every case the valleys as we now see them are valleys of erosion; in each and every case the mountains are mountains of circumdenudation; they project as eminences because the rock-masses which formerly surrounded them have been gradually removed. we have only to protract the outcrops of the denuded strata--to restore their continuations--to form some faint idea of the enormous masses of rock which have been carried away from the surface of the highland area since the strata were folded and fractured. all this erosion speaks to the lapse of long ages. the mountains of elevation which doubtless at one time existed within the highland area had already, as we have seen, suffered extreme erosion before the beginning of old red sandstone times, much of the area having been converted into an undulating plateau or plain, which, becoming submerged in part, was gradually overspread by the sedimentary deposits of the succeeding old red sandstone period. those sediments were doubtless derived in large measure from the denudation of the older rocks of the highlands, and since they attain in places a thickness of , feet, and cover many square miles, they help us to realise in some measure the vast erosion the highland area had sustained before the commencement of the carboniferous period. nor must we forget that the old red sandstone formation which borders the highlands has itself experienced excessive denudation: it formerly had a much greater extension, and doubtless at one time overspread large tracts of the highlands. again, we have to remember that during the carboniferous and permian periods, and the later mesozoic and cainozoic eras, the highlands probably remained more or less continuously in the condition of land. bearing this in mind, we need not be surprised that not a vestige of the primeval configuration brought about by the great earth-movements of late silurian times has been preserved. indeed, had the highland area, after the disappearance of the old red sandstone inland seas, remained undisturbed by any movement of elevation or depression, it must long ago have been reduced by sub-aërial erosion to the condition of a low-lying undulating plain. but elevation en masse from time to time took place, and so running water and its numerous allies have been enabled to carry on the work of denudation. thus in the geological history of the scottish highlands we may trace the successive phases through which many other elevated tracts have passed. the scandinavian plateau, and many of the mountains of middle germany--such, for example, as the harz, the erzgebirge, the thüringer-wald, etc.--show by their structure that they have undergone similar changes. first we have an epoch of mountain-elevation, when the strata are squeezed and crushed laterally, fractured and shattered--the result being the production of a series of more or less parallel anticlines and synclines, or, in other words, a true mountain-chain. next we have a prolonged period of erosion, during which running water flows through synclinal troughs, works along the backs of broken and shattered anticlines, and makes its way by joints, gaping cracks, and dislocations, to the low grounds. as time goes on, the varying character of the rocks and the mode of their arrangement begin to tell: the weaker structures are broken up; rock-falls and landslips ever and anon take place; anticlinal ridges are gradually demolished, while synclines tend to endure, and thus grow, as it were, into hills, by the gradual removal of the more weakly-constructed rock-masses that surround them. valleys continue to be deepened and widened, while the intervening mountains, eaten into by the rivers and their countless feeders, and shattered and pulverised by springs and frosts, are gradually narrowed, interrupted, and reduced, until eventually what was formerly a great mountain-chain becomes converted into a low-lying undulating plain. should the region now experience a movement of depression, and sink under the sea, new sedimentary deposits will gather over its surface to a depth, it may be, of many hundreds or even thousands of feet. should this sunken area be once more elevated en masse--pushed up bodily until it attains a height of several thousand feet--it will form a plateau, composed of a series of horizontal strata resting on the contorted and convoluted rocks of the ancient denuded mountain-chain. the surface of the plateau will now be traversed by streams and rivers, and in course of time it must become deeply cleft and furrowed, the ground between the various valleys rising into mountain-masses. should the land remain stationary, its former fate shall again overtake it; it will inevitably be degraded and worn down by the sub-aërial agents of erosion, until once more it assumes the character of a low-lying undulating plain. through such phases our highlands have certainly passed. at a very early epoch the archæan rocks of the north-west were ridged up into great mountain-masses, but before the beginning of the pre-cambrian period wide areas of those highly-contorted rocks had already been planed across, so that when subsidence ensued the pre-cambrian sandstones were deposited upon a gently undulating surface of highly convoluted strata. another great epoch of mountain-making took place after lower silurian times, and true mountain-ranges once more appeared in the highland area. we cannot tell how high those mountains may have been, but they might well have rivalled the alps. after their elevation a prolonged period of erosion ensued, and the lofty mountain-land was reduced in large measure to the condition of a plain, wide areas of which were subsequently overflowed by the inland seas of old red sandstone times--so that the sediments of those seas or lakes now rest with a violent unconformity on the upturned and denuded edges of the folded and contorted silurian strata. at a later geological period the whole highland area was elevated _en masse_, forming an undulating plateau, traversed by countless streams and rivers, some of which flowed in hollows that had existed before the beginning of old red sandstone times. since that epoch of elevation the highland area, although subject to occasional oscillations of level, would appear to have remained more or less continuously in the condition of dry land. the result is, that the ancient plateau of erosion has been deeply incised--the denuding agents have carved it into mountain and glen--the forms and directions of which have been determined partly by the original surface-slopes of the plateau, and partly by the petrological character of the rocks and the geological structure of the ground. [illustration: plate ii. influence of rock structure on the form of the ground. fig. . plateau of accumulation: horizontal strata, denuded. fig. . synclinal (s.o.) and anticlinal (e.) strata, denuded. fig. . faulted strata, showing denudation. fig. . mountain of accumulation,--volcano. fig. . diagrammatic section of a typical mountain chain, or mountains of upheaval. fig. . types of rock structure in the alps (after prof. heim) _the dotted lines show portions of strata, denuded._ fig. . escarpments (e) and dip slopes (d). fig. . erosion of anticlinal mountains. fig. . plateau of erosion, showing mountains of circumdenudation (aa). fig . section across ben lawers and loch tay, showing mountains of circumdenudation. the edinburgh geographical institute j. g. bartholomew f.r.g.s. ] thus, in the evolution of the surface-features of the earth, the working of two great classes of geological agents is conspicuous--the subterranean and the sub-aërial. the sinking down of the crust upon the cooling nucleus would appear to have given rise to the great oceanic depressions and continental ridges, just as the minor depressions within our continental areas have originated many mountain-chains. in the area undergoing depression the strata are subjected to intense lateral pressure, to which they yield along certain lines by folding up. the strata forming the alps, which are miles broad, originally occupied a width of miles; and similar evidence of enormous compression is conspicuous in the structure of all mountains of elevation. great elevation, however, may take place with little or no disturbance of stratification: wide continental areas have been slowly upheaved _en masse_, and sea-bottoms and low-lying plains have in this way been converted into lofty plateaux.[f] many of the most conspicuous features of the earth's surface, therefore, are due directly to subterranean action. all those features, however, become modified by denudation, and eventually the primeval configuration may be entirely destroyed, and replaced by contours which bear no direct relation to the form of the original surface. (see fig. .) in the newer mountain-chains of the globe the surface-features are still largely those due directly to upheaval; so in some recently elevated plateaux the ground has not yet been cut up and converted into irregular mountain-masses. many of the more ancient mountain-chains and ranges, however, have been exposed so long to the abrading action of the denuding agents that all trace of their original contour has vanished. and in like manner plateaux of great age have been so highly denuded, so cut and carved by the tools of erosion, that their plateau character has become obscured. they have been converted into undulating mountainous and hilly regions. everywhere throughout the world we read the same tale of subsidence and accumulation, of upheaval and denudation. the ancient sedimentary deposits which form the major portion of our land-surfaces, are the waste materials derived from the demolition of plains, plateaux, and mountains of elevation. in some mountain-regions we read the evidence of successive epochs of uplift, separated by long intervening periods of erosion, followed by depression and accumulation of newer sediments over the denuded surface. thus the alps began to be elevated towards the close of palæozoic times. erosion followed, and subsequently the land became depressed, and a vast succession of deposits accumulated over its surface during the long-continued mesozoic era into early cainozoic times. again, a great upheaval ensued, and the mesozoic and eocene strata were violently contorted and folded along the flanks of the chain. then succeeded another period of erosion and depression, which was again interrupted by one or more extensive upheavals. away from those lines of weakness which we call mountain-chains, we constantly encounter evidence of widespread movements of elevation, during which broad areas of sea-bottom have been upheaved to the light of day, and, after suffering extensive denudation have subsided, to be again overspread with the spoils of adjacent lands, and then upheaved once more. and such oscillations of level have occurred again and again. looking back through the long vista of the past, we see each continental area in a state of flux--land alternating with sea, and sea with land--mountains and plateaux appearing and disappearing--a constant succession of modifications, brought about by the antagonistic subterranean and sub-aërial agents. the hills are shadows, and they flow from form to form, and nothing stands; they melt like mists, the solid lands, like clouds they shape themselves and go. [f] this is the generally accepted view of modern geologists. it is very difficult, however, to understand how a wide continental area can be vertically upheaved. it seems more probable that the upheaval of the land is only apparent. the land seems to rise because the sea retreats as the result of the subsidence of the crust within the great oceanic basins. see article xiv. ( .) iv. the cheviot hills.[g] [g] from _good words_ for . i. the ridge of high ground that separates england from scotland is not, like many other hilly districts, the beloved of tourists. no guide-book expatiates upon the attractiveness of the cheviots; no cunningly-worded hotel-puffs lure the unwary vagrant in search of health, or sport, or the picturesque, to the quiet dells and pastoral uplands of the borders. since the biographer of dandie dinmont, of joyous memory, joined the shades, no magic sentences, either in verse or prose, have turned any appreciable portion of the annual stream of tourists in the direction of the cheviots. the scenery is not of a nature to satisfy the desires of those who look for something piquant--something "sensational," as it were. it is therefore highly improbable that the primeval repose of these border uplands will ever be disturbed by inroads of the "travelling public," even should some second burns arise to render the names of hills and streams as familiar as household words. and yet those who can spare the time to make themselves well acquainted with that region should do so; they will have no reason to regret their visit, but very much the reverse. for the scenery is of a kind which grows upon one. it shows no clamant beauties--you cannot have its charms photographed--the passing stranger may see nothing in it to detain him; but only tarry for a while amongst these green uplands, and you shall find a strange attraction in their soft outlines, in their utter quiet and restfulness. for those who are wearied with the crush and din of life, i cannot think of a better retreat. one may wander at will amongst the breezy hills, and inhale the most invigorating air; springs of the coolest and clearest water abound, and there are few of the brooks in their upper reaches which will not furnish natural shower-baths. did the reader ever indulge in such a mountain-bath? if not, then let him on a summer day seek out some rocky pool, sheltered from the sun, if possible, by birch and mountain-ash, and, creeping in below the stream where it leaps from the ledges above, allow the cool water to break upon his head, and he will confess to having discovered a new aqueous luxury. then from the slopes and tops of the hills you have some of the finest panoramic views to be seen in this island. nor are there wanting picturesque nooks, and striking rock scenery amongst the hills themselves: the sides of the cheviot are seamed with some wild, rugged chasms, which are just as weird in their way as many of the rocky ravines that eat into the heart of our highland mountains. the beauty of the lower reaches of some of the streams that issue from the cheviots is well known; and few tourists who enter the vale of the teviot neglect to make the acquaintance of the sylvan jed. but other streams, such as the bowmont, the kale, the oxnam, and the rule will also well repay a visit. in addition to all these natural charms, the cheviot district abounds in other attractions. those who are fond of border lore, who love to seek out the sites of old forays, and battles, and romantic incidents, will find much to engage them; for every stream, and almost every hill, is noted in tale and ballad. or if the visitor have antiquarian tastes, he may rival old monkbarns, and do his best to explain the history of the endless camps, ramparts, ditches, and terraces which abound everywhere, especially towards the heads of the valleys. to the geologist the district is not less interesting, as i hope to be able, in the course of these papers, to show. the geological history of the cheviots might be shortly summed up, and given in a narrative form, but it will perhaps be more interesting, and, at the same time more instructive, if we shall, instead, go a little into detail, and show first what the nature of the evidence is, and, second, how that evidence may be pieced together so as to tell its own story. i may just premise that my descriptions refer almost exclusively to the scottish side of the cheviots--which is not only the most picturesque, but also the most interesting, both from an antiquarian and geological point of view. the cheviots extend from the head of the tyne in northumberland, and of the liddel in roxburghshire, to yeavering bell and the heights in its neighbourhood (near wooler), a distance of upwards of thirty miles. some will have it that the range goes westward so as to include the heights about the source of the teviot, but this is certainly a mistake, for after leaving peel fell and crossing to the heights on the other side of the liddel water, we enter a region which, both in its physical aspect and its geological structure, differs considerably from the hilly district that lies between peel fell and the high-grounds that roll down to the wide plains watered by the glen and the till. the highest point in the range is that which gives its name to the hills--namely, the cheviot--a massive broad-topped hill, which reaches an elevation of feet above the sea, and from which a wonderful panorama can be scanned on a clear day. the top of the hill is coated with peat, fifteen to twenty feet thick, in some places. a number of deep ravines trench its slopes, the most noted of which are hen hole and the bizzle. peel fell, at the other extremity of the range, is only feet high, while the dominant points between peel fell and the cheviot are still lower--ranging from feet to feet. the general character of the hills is that of smooth rounded masses, with long flowing outlines. there are no peaks, nor serrated ridges, such as are occasionally met with in the northern highlands; and the valleys as a rule show no precipitous crags and rocky precipices, the most conspicuous exceptions being the deep clefts mentioned as occurring in the cheviot. the hills fall away with a long gentle slope into england, while on the scottish side the descent is somewhat abrupt; so that upon the whole the northern or scottish portion of the cheviots has more of the picturesque to commend it than the corresponding districts in england. indeed, the opposite slopes of the range show some rather striking contrasts. the long, flat-topped elevations on the english side, that sweep south and south-west from carter fell and harden edge, and which are drained by the tyne, the rede water, and the coquet, are covered for the most part with peat. sometimes, however, when the slope is too great to admit of its growth, the peat gives place to rough scanty grass and scrubby heath, which barely suffice to hide the underlying barren sandstone rocks. one coming from the scottish side is hardly prepared, indeed, for the dreary aspect of this region as viewed from the dominant ridge of the cheviots. if in their physical aspect the english slopes of these hills are for the most part less attractive than the scottish, it is true also that they offer less variety of interest to the geologist. those who have journeyed in stagecoaching times from england into scotland by carter fell, will remember the relief they felt when, having surmounted the hill above whitelee, and escaped from the dreary barrens of the english border, they suddenly caught a sight of the green slopes of the scottish hills, and the well-wooded vales of edgerston burn and jed water. on a clear day the view from this point is very charming. away to the west stretch in seemingly endless undulations the swelling hills that circle round the upper reaches of teviotdale. to east and north-east the eye glances along the bright-green cheviots of the scottish border, and marks how they plunge, for the most part somewhat suddenly, into the low grounds, save here and there, where they sink in gentler slopes, or throw out a few scattered outposts--abrupt verdant hills that somehow look as if they had broken away from the main mass of the range. from the same standpoint one traces the valleys of the rule and the jed--sweetest of border streams--stretching north into the well-clothed vale of the teviot. indeed, nearly the whole of that highly-cultivated and often richly-wooded country that extends from the base of the cheviots to the foot of the lammermuirs, lies stretched before one. here and there abrupt isolated hills rise up amid the undulating low grounds, to hide the country behind them. of these the most picturesque are dark rubers law, overlooking the rule water; minto crags, and penielheugh with its ugly excrescence of a monument, both on the north side of the teviot; and the eildon hills, which, as all the world knows, are near melrose. after he has sated himself with the rare beauty of this landscape (and still finer panoramic views are to be had from the top of blackhall hill, hownam law, the cheviot, as also from various points on the line of the roman road and other paths across the hills into england), the observer will hardly fail to be struck by the great variety of outlines exhibited. some of the hills, especially those to the west and north-west, are grouped in heavy masses, and present for the most part a soft, rounded contour, the hills being broad atop and flowing into each other with long, smooth slopes. other elevations, such as those to the east and north-east of carter fell, while showing similar long gentle slopes, yet are somewhat more irregular in form and broken in outline, the hills having frequently a lumpy contour. very noteworthy objects in the landscape also are the little isolated hills of the low grounds, such as rubers law, and the dunian, above jedburgh. they rise, as i have said, quite suddenly out of that low gently undulating country that sinks softly into the vales of the teviot and the tweed. this variety arises from the geological structure of the district. the hills vary in outline partly because they are made up of different kinds of rock, and partly owing to the mode in which these rocks have been arranged. but notwithstanding all this variety of outline, one may notice a certain sameness too. flowing outlines are more or less conspicuous all over the landscape. many of the hills, especially as we descend into teviotdale, seem to have been smoothed or rounded off, as it were, so as to present their steepest faces as a rule towards the south-west. and if we take the compass-bearing of the hill-ridges of the same district, we shall find that these generally trend from south-west to north-east so much, then, at present for the surface configuration of the cheviot region. when we come to treat of the various rock-masses, and to describe the superficial accumulations underneath which these are often concealed, we shall be in a better position to give an intelligible account of the peculiar form of the ground, and the causes to which that configuration must be ascribed. the solid rocks which enter into the composition of the cheviots consist mainly of ( ) hard grey and blue rocks, called _greywacké_ by geologists, with which are associated blue and grey shale; ( ) various old igneous rocks; and ( ) sandstones, red and white, interbedded with which occur occasional dark shales. now, before we can make any endeavour towards reconstructing in outline the physical geography of the cheviot hills during past ages, it is necessary that we should discover the order in which the rock-masses just referred to have been amassed. i shall first describe, therefore, some sections where the members of the different series are found in juxtaposition, for the purpose of pointing out which is the lowest-lying, and consequently the oldest, and which occupy the uppermost and intermediate positions. [illustration: fig .--conglomerate and red sandstone, etc., _c_, resting on greywacké and shale, _g_.] the first section to which reference may be made is exposed in the course of the river jed, at allars mill, a little above jedburgh. this section is famous in its way as having been described and figured by dr. hutton, who may be said to have founded the present system of physical geology. in the bed of the stream are seen certain confused ridges of a greyish blue rock running right across the river course--that is, in a direction a little north of east and south of west. these ridges are the exposed edges of beds of greywacké and shale, which are here standing on end. the beds are somewhat irregular, being inclined from the vertical, now in one direction and now in another, or, as a geologist would say, the "dip" changes rapidly, sometimes being up the valley and sometimes down. the same beds continue up the steep bank of the river for a yard or two, and are there capped by another set of rocks altogether, namely, by soft red sandy beds which at the bottom become _conglomeratic_--that is to say, they are charged with water-worn stones. the annexed diagram (fig. ) will show the general appearances presented: _g_ represents the vertical greywacké and shale, and _c_ the overlying deposits of conglomerate and red sandy beds. now let us see what this section means. what, in the first place, is greywacké? the term itself has really no meaning, being a name given by the miners in the harz mountains to the unproductive rocks associated with the vein-stones which they work. when we break the rock we may observe that it is a granular mixture of small particles of quartz, to which sometimes felspar and other minerals are added. the grains are bound together in a hardened matrix of argillaceous or clayey and silicious matter, blue, or grey, or green, or brown and yellow, as the case may be. at allars mill, and generally throughout the cheviot district, the prevailing colour is a pale greyish blue or bluish grey; but shades of green and brown often occur. the component particles of the rock are usually rounded or water-worn. again, we notice that the ridges and bands of rock that traverse the course of the jed at allars mill are merely the outcrops of successive _strata_ or beds. it is clear then that greywacké and the grey shales that accompany it are _aqueous_ rocks--that is to say, they consist of hardened sediment, which has undoubtedly been deposited in successive layers of variable thickness by water in motion. but since the sediments of rivers and currents are laid down in approximately horizontal planes, it is evident that if the greywacké and shale be sedimentary deposits they have suffered considerable disturbance since the time of their formation; for, as we have seen, the beds, instead of being horizontal or only gently inclined, actually approach the vertical. the fact is, that the outcrops which we see are only the truncated portions of what were formerly rapid undulations or folds of the strata, the tops of the folds or arches having been cut away by geological agencies, to which i shall refer by-and-by. what were at one time horizontal strata have been crumpled up into great folds, the folds being squeezed tightly together, and their upper portions planed away before the overlying red sandy beds were laid down. the accompanying diagram (fig. ) may serve to make all this clearer. let a a represent the present surface of the ground, and b b a depth of say fifty feet or a hundred feet from the surface. the continuous lines between a and b represent the greywacké beds as we now see them in section; the dotted lines above a a indicate the former extension of the strata, and the dotted lines below b b their continuation below that datum line. hence it is obvious that in a succession of vertical or highly inclined beds, we may have the same strata repeated many times, the same beds coming again and again to the surface. thus the stratum at s is evidently the same bed as that at w, x, y, and z. [illustration: fig .] such great foldings or redoublings of strata are most probably originated during subsidence of a portion of the earth's crust. while the ground is slowly sinking down, the strata underneath are perforce compelled to occupy less space laterally, and this they can only do by yielding amongst themselves. all folding or contortion on the large scale--that, namely, which has affected areas of strata extending over whole countries--seems to have taken place under great pressure; in other words, to have been produced at considerable depths from the earth's surface. we can conceive, therefore, of a wide tract of land sinking down for hundreds of feet, and producing at the surface comparatively little change. but a depression of a few hundred feet at the surface implies a considerably greater depression at a depth of several thousand feet from the surface, and it is at great depths, therefore, that the most violent folding must take place. consequently considerable contortion, and much folding, and lateral crushing and reduplication of strata may occur, and yet no trace of this be observable at the surface, save only a gentle depression. for example, in greenland, a movement of subsidence has been going on for many years--the land has been slowly sinking down. the rocks at the surface are of course quite undisturbed by this widely-extended movement, but the strata at great depths may be undergoing much compression and contortion. it follows from such considerations, that if we now get highly contorted strata covering wide areas at the surface, we suspect that very considerable _denudation_ has taken place. that is to say, large masses of rock have been removed by the geological agents of change, so as to expose the once deeply-buried tops of the arched or curved and folded strata. we may therefore infer from a study of the phenomena in the jed at allars mill, first, that the red sandy beds are younger than the greywacké and shale, seeing that they rest upon them; and, second, that a very long period of time must have elapsed between the deposition of the older and the accumulation of the younger set of strata; for it is obvious that considerable time was required for the consolidation and folding of the greywacké, and an incalculable lapse of ages was also necessary to allow of the gradual wearing away by rain, frost, and running water of the great thickness of rocks underneath which the greywacké was crumpled. and all this took place before the horizontally-bedded red sandstone and conglomerate gathered over the upturned ends of the underlying strata. the succession of rocks at allars mill is seen in many other places in the cheviot district, but enough has been said to prove that the greywacké beds are the older of the two sets of strata. there is another class of rocks, the relative position of which we must now ascertain, for no one shall wander much or far among the cheviots without becoming aware of the existence of other kinds of rock than greywacké and sandstone. many of the hills east of oxnam and jed waters, for example, are composed of igneous masses--of rocks which have had a volcanic origin. as we shall afterwards see, the whole north-eastern section of the cheviots is built up of such rocks. at present, however, we are only concerned with the relation which these bear to the greywacké and the red sandy beds. now at various localities--for example, in edgerston burn, on the hill-face south of plenderleith, and again along the steep front of hindhope and blackball hills, which are on the crest of the cheviots--we find that the igneous rocks rest upon the greywacké and shale (see fig. ) precisely in the same way as do the red sandy beds. they therefore belong to a later date than the greywacké. in other places, again, we meet with the conglomerates and red sandstones (_c_, fig. ) resting upon and wrapping round the igneous rocks, _i_, and thus it becomes quite obvious that the latter occupy an intermediate position between the greywacké and shale on the one hand, and the conglomerate and red sandstone upon the other. [illustration: fig. .--igneous rocks (_i_, _a_) resting on greywacké and shale, _g_.] [illustration: fig. .--_c_, conglomerate and sandstones, resting on igneous rocks, _i_.] we have now cleared the way so far, preparatory to an attempt to trace the geological history of the cheviots. the three sets of rocks, whose mutual relations we have been studying, are those of which the district is chiefly composed; but, as we shall see in the sequel, there are others, not certainly of much extent, but nevertheless having an interesting story to tell us. nor shall we omit to notice the superficial accumulations of clay, gravel, sand, silt, alluvium, and peat; monuments as they are of certain great changes, climatic and geographical, which have characterised not the cheviots only, but a much wider area. ii. if we draw a somewhat straight line from girvan, on the coast of ayrshire, in a north-east direction to the shores of the north sea, near dunbar, we shall find that south of that line, up to the english border, nearly the whole country is composed of various kinds of greywacké and shale like the basement beds of the cheviot district. here and there, however, especially in certain of the valleys and some of the low-lying portions of this southern section of scotland, one comes upon small isolated patches and occasional wider areas of younger strata, which rest upon and conceal the greywackés and shales. such is the case in teviotdale, the cheviot district, and the country watered by the lower reaches of the tweed, in which regions the bottom beds are hidden for several hundreds of square miles underneath younger rocks. indeed, the greywacké and shale form but a very small portion of the surface in the cheviots, appearing upon a coloured geological map like so many islands or fragments, as it were, which have somehow been detached from the main masses of greywacké of which the lammermuirs and the uplands of dumfries and selkirk shires are composed. although the bottom rocks of the cheviot hills are thus apparently separated from the great greywacké area, there can be no doubt that they are really connected with it, the connection being obscured by the overlying younger strata. for if we could only strip off these latter, if we could only lift aside the great masses of igneous rock and sandstone that are piled up in the cheviot hills and the adjoining districts, we should find that the bottom upon which these rest is everywhere greywacké and shale. in part proof of this it may be mentioned that at various places in those districts which are entirely occupied by sandstone and igneous rock, the streams have cut right down through the younger rocks so as to expose the bottom beds, as in jed water at allars mill. again, when we trace out the boundaries of any detached areas of greywacké we invariably find these bottom beds disappearing on all sides underneath the younger strata by which they are surrounded. one such isolated area occurs in the basin of the oxnam water, between littletonleys and bloodylaws, a section across which would exhibit the general appearance shown in the accompanying diagram (fig. ). another similarly isolated patch is intersected by edgerston burn and the jed water between paton haugh and dovesford. but the largest of these detached portions appears, forming the crest of the cheviots, at the head of the river coquet. there the basement beds occupy the watershed, extending westward, some three or four miles, as far as the sandstones of hungry law, while to the north and east they plunge under the igneous rocks of brownhart law and the hindhope hills. now it is evident that all those detached and isolated areas of greywacké and shale are really connected underground, and not only so, but they also piece on in the same way to the great belt of similar strata that stretches from sea to sea across the whole breadth of scotland. indeed, we may observe in the cheviot district how long and massive promontories of greywacké jut out from that great belt, and extend often for miles into the areas that are covered with younger strata, as, for example, in the brockilaw and wolfelee hills. a generalised section across the greywacké regions of the cheviot hills would therefore present the appearances shown in the annexed diagram (fig. ), in which g represents the basement beds, i the igneous rocks, and c the red sandstones, etc. [illustration: fig. .--section across greywacké area of oxnam water; g, greywacké and shale; c, sandstone, etc.] [illustration: fig. .--diagram section across greywacké districts of cheviot hills.] throughout the whole of the district under review the bottom beds are observed to dip at a high angle--the strata in many places being actually vertical--and the edges or crops of the strata run somewhat persistently in one direction, namely, from south by west to north by east; or, as a geologist would express it, the beds have an approximately south-west and north-east "strike." now as the dip is sometimes to north-west and sometimes to south-east, it is evident that the rocks have been folded up in a series of rapid convolutions, and that some of the beds must be often repeated. from the character of the fossils which the bottom beds have yielded we learn that the strata belong to that division of past time which is known as the silurian age. these fossils appear to be of infrequent occurrence, and the creatures of which they are the relics occupied rather a humble place in the scale of being. they are called _graptolites_ (from their resemblance to pens), an extinct group of hydroid zoophytes, apparently resembling the sertularians of our own seas. the general appearance of the silurian strata of the cheviots is indicative of deposition in comparatively quiet water, but how deep that water was one cannot say. upon the whole, the beds look not unlike the sediments that gather in calm reaches of the sea, such as estuaries, betokening the presence of some not distant land from which fine mud and sand were washed down. another proof that some of the strata at all events were accumulated not far from a shore-line, is found in certain coarse bands of grit and pebbles, which are not likely to have been formed in deep water. this evidence, however, cannot be considered decisive, and in the present state of our knowledge all that we can assert with anything like confidence is simply this:--that during the deposition of the silurian strata the whole of the cheviot area lay under water--existed, in short, as a muddy sea-bottom, in the slime of which flourished here and there, in favourable spots, those minute hydroid animals called _graptolites_. between the deposition of the silurian and the formation of the rocks that come next in order a long interval elapsed, during which the mud, sand, and grit that gathered on the floor of the ancient sea were hardened into solid masses, and eventually squeezed together into great folds and undulations. it has already been pointed out that these changes could hardly have been effected save under extreme pressure, and this consideration leads us to infer that a great thickness of strata has been removed entirely from the cheviot district, so as to leave no trace of its former existence. long before the deposition of the younger strata that now rest upon and conceal the silurian rocks, the action of the denuding forces--the sea, frosts, rain, and rivers--had succeeded in not only sweeping gradually away the strata underneath which the bottom beds were folded, but in deeply scarping and carving these bottom beds themselves. can we form any reasonable conjecture as to the geological age of the strata underneath which the bottom beds of the cheviots were folded, and which, as we have seen, had entirely disappeared before the younger rocks of the district were accumulated? well, it is obvious that the missing strata must have been of later formation than the bottom beds, and it is equally evident that they must have been of much more ancient date than the igneous rocks of the cheviot hills. now, as we shall afterwards see, these igneous rocks belong to the old red sandstone age, that is to say, to the age that succeeded the silurian. how is it then, if the bottom beds be really of silurian and the igneous rocks of old red sandstone age, that a gap is said to exist between them? the explanation of this apparent contradiction is not far to seek. when we compare the fossils that occur in the silurian strata of the cheviot hills and the districts to the west, with the organic remains disinterred from similar strata elsewhere, as in wales for example, we find that the bottom beds of the cheviots were in all probability accumulated at approximately the same time as certain strata that occur in the middle division of the upper silurian. in wales and in cumberland the strata that approximate in age to the silurian of the cheviots are covered by younger strata belonging to the same formation which reach a thickness of several thousand feet. it may quite well be, therefore, that the succession of silurian strata in the cheviots was at one time more complete than it is now. the upper portions of the formation which are so well developed in wales and cumberland, and which are likewise represented to a small extent in scotland, had in all probability their equivalents in what are our border districts. in other words, there are good grounds for believing that the existing silurian rocks of the cheviots were in times preceding the old red sandstone age covered with younger strata belonging to the same great system. the missing silurian strata of the cheviots may have attained a thickness of several thousand feet, and underneath such a mass of solid rock the lower-lying strata might well have been consolidated and subsequently squeezed into folds. we now pass on to consider the next chapter in the geological history of the cheviot hills. as we proceed in our investigations it will be noticed that the evidence becomes more abundant, and we are thus enabled to build up the story of the past with more confidence, and with fuller details. for it is with geological history as with human records--the further back we go in time the scantier do the facts become. the rocks upon which nature writes her own history are palimpsests, on which the later writing is ever the most easily deciphered. nay, she cannot compile her newer records without first destroying some of those compiled in earlier times. the sediments accumulating in modern lake and sea are but the materials derived from the degradation of the rocks we see around us, just as these in like manner have originated from the demolition of yet older strata. thus the further we trace back the history of our earth, the more fragmentary must we expect the evidence to be; and conversely, the nearer we approach to the present condition of things the more abundant and satisfactory must the records become. accordingly, we find that the igneous rocks of the cheviot hills tell us considerably more than the ancient silurian deposits upon which they rest. the surface of the latter appears to be somewhat irregular underneath the igneous rocks, showing that hills and valleys, or an undulating table-land, existed in the cheviot district prior to the appearance of the younger formation. but before we attempt to summarise the history of that formation, it is necessary to give some description, however short, of the rocks that compose it. these consist chiefly of numerous varieties of a rock called porphyrite by geologists, piled in more or less irregular beds, one on top of another, in a somewhat confused manner. the colour of the freshly fractured rocks is very variable, being usually some shade of blue or purple; but pink, red, brown, greenish, and dark grey or almost black varieties also occur. some of the rocks are finely crystalline; others, again, are much coarser, while many are compact, or nearly so, a lens being required to detect a crystalline texture. the mineral called felspar is usually scattered more or less abundantly through the matrix or base, which itself is composed principally of felspathic materials. besides distinct scattered crystals of felspar, other minerals often occur in a similar manner; mica and hornblende being the commonest. occasionally the rocks contain numerous circular, oval, or flattened cavities, which are sometimes so abundant as to give the appearance of a kind of coarse slag to the porphyrite. these little cavities, however, are usually filled up with mineral matter--such as calcspar, calcedony, jasper, quartz, etc. sometimes also cracks, crannies, and crevices of some size have been sealed up with similar minerals. now nearly all these appearances are specially characteristic of rocks which have at one time been in a state of igneous fusion; nor can there be any doubt that the cheviot porphyrites are merely solidified lava-beds, which have been poured out from the bowels of the earth. in modern lavas we may notice not only a crystalline texture, but frequently also we observe those in our porphyrites. such cavities are due to the expansive force of the vapours imprisoned in the molten mass at the time of eruption. they form chiefly towards the upper surface of a lava stream, and are often drawn out or flattened in the direction in which the lava flows. thus a stream of lava, as it creeps on its way, becomes slaggy and scoriaceous or cindery above and in front, and as the molten mass within continues to flow, the slags and cinders that cover its face tumble down before it, and form the pavement upon which the stream advances. in this way slags and cinders become incorporated with the bottom of the lava, and hence it is that so many volcanic rocks are scoriaceous, as well below as above. the vapours which produce the cavities usually contain minerals in solution, and these, as the lava cools, are frequently deposited, partially filling up the vesicles, so as to form what are called geodes. but many of the cavities have been filled in another way--by the subsequent infiltration of water carrying mineral matter in solution. and since we know that all rocks are so permeated by water, it is clear that the cavities may have received their contents during many successive periods, after the solidification of the rock in which they occur. it is in this manner that the jaspers, calcedony, and beautiful agates of commerce have been formed. rocks abundantly charged with cavities are said to be _vesicular_, and when the vesicles are filled with mineral matter, then the mass becomes, in geological language, _amygdaloidal_, from the almond-like shape assumed by the flattened vesicles. now all the appearances described above, and many others hardly less characteristic of true lavas, are to be met with amongst those porphyrites which, as i have said, form the major portion of the cheviot hills. from the valley of the oxnam, east by cessford, morebattle, and hoselaw, and south by edgerston, letham, browndeanlaws, and hindhope, the porphyrites extend over the whole area, sweeping north-east across the border on to the heights above the rivers glen and till. in the hills at hindhope we notice a good display of the oldest beds of the series. at the base occurs a very peculiar rock resting upon the silurian, and thus forming the foundation of the porphyrites. it varies in colour, being pink, grey, green, red, brown, or variously mottled. sometimes it is fine-grained and gritty, like a soft, coarse-grained sandstone; at other times it is not unlike a granular porphyrite; but when most typically developed it consists of a kind of coarse angular gravel embedded in a gritty matrix. the stones sometimes show distinct traces of arrangement into layers; but they are often heaped rudely together with little or no stratification at all. they consist chiefly of fragments of porphyrites; but bits of silurian rocks also occur amongst them. this peculiar deposit unquestionably answers to the heaps of dust, sand, stones, and bombs which are shot out of modern volcanoes; it is a true tuff--that is, a collection of loose volcanic ejectamenta. upon what kind of surface did it fall? long before the eruptions began, the silurian rocks had been sculptured into hills and valleys by the action chiefly of the sub-aërial forces, and it was upon these hills and in these valleys that the igneous materials accumulated. it is difficult to say, however, whether at this period the cheviot district was above or under water. the traces of bedding in the tuff would seem to indicate the assorting power of water; but the evidence is too slight to found upon, because we know that in modern eruptions, loose ejectamenta frequently assume a kind of irregular bedded arrangement. for aught we can say to the contrary, therefore, dry land may have extended across what is now southern scotland and northern england when the first rumblings of volcanic disturbance shook the cheviot area. be that as it may, we know that the volcanic outbursts began in those old times, as they almost invariably commence now, by a discharge of sand, small stones, blocks, and cinders. these, we may infer, covered a wide area round the centre of dispersion--the chief focus of eruption being probably in the vicinity of the big cheviot, where a mass of granite seems to occupy the core or deep-seated portion of the old volcanic centre. the locality where the tuff occurs is some nine miles or so distant from this point, and the intervening ground could hardly have escaped being more or less thickly sprinkled with the same materials. the whole of that intervening ground, however, now lies deeply buried under the massive streams of once-molten rock that followed in succession after the first dispersion of stones and débris. although, as i have said, it may be doubted whether at the beginning of their activity the cheviot volcanoes were sub-aqueous, yet there are not a few facts that lead to the inference that the eruption of the porphyrites took place for the most part, if not exclusively, under water. the beds are occasionally separated by layers of sandstone, grit, and conglomerate; but such beds are rare, and true tuffs are rarer still. if the outbursts had been sub-aërial, we ought surely to have met with these latter in greater abundance, while we should hardly have expected to find such evidently water-arranged strata as do occur here and there. the porphyrites themselves present certain appearances which lead to the same conclusion. thus we may observe how the bottoms of the beds frequently contain baked or hardened sand and mud, showing that the molten rock had been poured out over some muddy or sandy bottom, and had caught up and enclosed the soft, sedimentary materials, which now bear all the marks of having been subjected to the action of intense heat. sometimes, indeed, the old lava-streams seem to have licked up beds of unconsolidated gravel, the water-worn stones being now scattered through their under portions. as no fossils occur in any of the beds associated with the porphyrites, one cannot say whether the latter flowed into the sea or into great freshwater lakes. neither can we be certain that towards their close the eruptions were not sub-aërial. they may quite well have been so. the porphyrites attain a thickness of probably not less than fifteen hundred or two thousand feet, and the beds which we now see are only the basal, and therefore the older portions of the old volcanoes. the upper parts have long since disappeared, the waste of the igneous masses having been so great that only the very oldest portions now remain, and these, again, are hewn and carved into hill and valley. any loose accumulation of stones and débris, therefore, which may have been thrown out in the later stages of the eruptions, must long ere this have utterly disappeared. we can point to the beds which mark the beginning of volcanic activity in the cheviots; we can prove that volcanoes continued in action there for long ages, great streams of lava being poured out--the eruptions of which were preceded and sometimes succeeded by showers of stones and débris; we can show, also, that periods of quiescence, more or less prolonged, occasionally intervened, at which times water assorted the sand and mud, and rounded the stones, spreading them out in layers. but whether this water action took place in the sea or in a lake we cannot tell. indeed, for aught one can say, some of the masses of rounded stones i refer to may point to the action of mountain torrents, and thus be part evidence that the volcanoes were sub-aërial. if we are thus in doubt as to some of the physical conditions that obtained in the cheviot district during the accumulation of the porphyrites and their associated beds, we are left entirely to conjecture when we seek to inquire into the conditions that prevailed towards the close of the volcanic period. for just as we have proof that before this period began the silurian strata had been subjected to the most intense denudation--had, in short, been worn into hill and valley--so do we learn from abundant evidence that the rocks representing the old volcanoes of the cheviots are merely the wrecks of formerly extensive masses. not only have the upper portions of these volcanoes been swept away, but their lower portions, likewise, have been deeply incised, and thousands of feet of solid rock have been carried off by the denuding forces. and by much the greater part of all this waste took place before the accumulation of those sandstones which now rest upon the worn outskirts of the old volcanic region. iii. some reference has already been made (see p. ) to the general appearance presented by the valleys of the cheviots. in their upper reaches they are often rough and craggy; narrow dells, in fact, flanked with steep shingle-covered slopes, and occasionally overlooked by beetling cliffs, or fringed with lofty scaurs of decomposing rocks. as we follow down the valleys they gradually widen out; the hill-slopes becoming less steep, and retiring from the stream so as to leave a narrow strip of meadow-land through which the clear waters canter gaily on to the low grounds of the teviot. in their middle reaches these upland dales are not infrequently well cultivated to a considerable height, as in the districts between hownam and morebattle, and between belford and yetholm--the former in the valley of the kale, and the latter in that of the bowmont. it is noticeable that all the narrower and steeper reaches lie among silurian strata and old red sandstone porphyrites. no sooner do we leave the regions occupied by these tough and hard rock-masses than the whole aspect of the scenery changes. the surrounding hills immediately lose in height and fall away into a softly undulating country, through which the streams and rivers have dug for themselves deep romantic channels. nevertheless, it is a fact, as we shall see by-and-by, that south-west of the region occupied by the igneous rocks of the cheviot hills, all the higher portions of the range (hungry law, carter fell, peel fell, etc.) are built up of sandstones. for the present, however, i confine attention to those valleys whose upper reaches lie either wholly or in part among igneous rocks or silurian strata. a typical and certainly the most beautiful example is furnished us by the vale of the river jed. this stream rises among the sandstone heights which have just been mentioned as composing the south-west portion of the cheviot range. the first seven or eight miles of its course lead us through a broad open valley, which has been hollowed out almost exclusively in sandstones and shales; by-and-by, however, we are led into a silurian tract, and thereupon the valley contracts and the hill-slopes descend more steeply to the stream. but we soon leave the grassy glades of this silurian tract and enter all at once upon what may be termed the lower reaches of the jed. no longer cooped up in the rocky gully, painfully worn for itself in the hard greywacké and shales, the stream now winds through a much deeper and broader channel which has evidently been excavated with greater ease. precipitous banks and scaurs here overlook the river at every bend, the banks becoming higher and higher and retiring further and further from each other, as the water glides on its way, until at last they fairly open upon the broad vale of the teviot. sometimes the river flows along one side of its valley for a considerable distance, and whenever this is the case, it gives us a line of bold cliffs which are usually flanked on the opposite side by sloping ground. this is the general character of all valleys of erosion, and especially of the lower reaches of the jed. a glance at the cliffs and scaurs of the jed shows that they consist of horizontal or gently undulating strata of soft earthy, friable, shaly sandstone, arranged in thin beds and bands, which alternate rapidly with crumbling, sandy, and earthy shales; the whole forming a loose and unconsolidated mass that readily becomes a prey to the action of the weather, rain, frost, and running water. the prevailing colour is a dull red, but pale yellow, white, green, and purple discolorations are visible when the strata are closely scanned. the finest sections occur between glen douglas and inchbonnie, and at mossburnford, but the cliffs throughout present the same general appearance, and are picturesque in the highest degree. everywhere the banks are thickly wooded, and even the steep red scaurs are dashed and flecked with greenery, which droops and springs from every ledge and crevice in which a root can fix itself. how vivid and striking is the contrast between the fresh delicate green of early summer and the rich warm tint of these rocks, which when lit up by the setting sun seem almost to glow and burn! well may the good folk of jedburgh be proud of the lovely valley in which their lot is cast. in no similar district in scotland will the artist meet with a greater number of such "delicious bits," in which all the charms of wood and water, of meadow and rock are so harmoniously combined. it is not with the scenic beauties of the jed, however, that we have at present to do. i wish the reader to examine with me certain appearances visible at the base of the red beds, where these rest upon those older rocks which have formed the subject of the preceding papers. in the bed of the river at jedburgh, we see the junction between the red beds and the silurian strata, and may observe how the bottom portions of the former, which repose immediately upon the greywackés, are abundantly charged with well-rounded and water-worn stones. many of these stones consist of greywacké, hardened grit, and other kinds of rock, and most of them undoubtedly have been derived from silurian strata. in other districts where the old igneous rocks of the cheviots form the pavement upon which the red beds repose, the stones in the lower portions of the latter are made up chiefly of rounded fragments of the underlying porphyrites. all which clearly shows that the red beds have been built out of the ruins of the older strata of the district. this is unquestionably the origin not only of the conglomerates, but of all the red beds through which the river jed cuts its way from the base of the hills to the teviot. when we trace out the boundary of these beds, we find that this leads us along the base of the hills, close to the hill-foot; and not only so, but it frequently takes us into the hill-valleys also. and this shows that the cheviots had already been deeply excavated by streams before any portion of the red beds was deposited. i have said that the red beds are approximately horizontal; sometimes, however, they have a decided _dip_ or inclination, and when this is continuous, it is invariably in a direction away from the hills. thus as we traverse the ground from the hill-foot to the teviot, we pass over the outcrops of the red beds and slowly rise from a lower to a higher geological position. the strata, however, are generally so flat that their dip is often not greater than the average slope or inclination of the ground. hence when we ascend the valley-slopes from the stream, we soon reach the higher beds of the series, as, for example, in the undulating heights that overlook the jed in the neighbourhood of jedburgh. in that district a number of quarries have been opened, in which the upper beds of the red series are well exposed, as at ferniehirst, tudhope, etc. these consist of thick beds of greyish white, yellowish, and reddish sandstones, which, unlike the crumbling earthy deposits below, are quite suitable for building purposes. scales of fish and plant remains are often met with in the thick sandstones, but the underlying earthy, friable red beds appear to be quite destitute of any organic remains. let us now briefly recapitulate the main facts we have just ascertained. they are these:-- . all the low grounds that abut upon the hills are composed of horizontal or nearly horizontal strata, which consist chiefly of red earthy beds, passing down into conglomerates, and up into whitish and reddish sandstones. . the conglomeratic portion forms the boundary of the series, fringing the outskirts of the hills, and resting sometimes upon silurian strata and sometimes upon old red sandstone igneous rocks. . fossils occur in the white and red sandstones, but seem to be wanting in the underlying red earthy beds. [illustration: fig. .--s, silurian strata; _i_, old red sandstone igneous rocks; _a^ _, conglomerate; _a^ _, red earthy beds; _a^ _, white and red sandstones.] the accompanying diagram (fig. ) gives a generalised view of the relation borne by the red beds to the older rocks of the cheviots. it will be seen that the former rest _unconformably_ upon the old red sandstone igneous rocks, and also, of course, upon the silurian strata. the section shows that the red beds lie upon a worn and denuded surface. now this speaks to the lapse of a long period of time. it may be remembered that we had some grounds for believing that the latest eruptions of the cheviot volcanoes were sub-aërial. the evidence now enables us to advance further, and to state that after the close of the volcanic period, the whole cheviot district existed as an elevated tract of dry land, from which streams flowed north and south. and for so long a time did these conditions endure, that the rivulets and streams were enabled to scoop out many channels and broad valleys before any of the outlying red beds had come into existence. before the conglomerate beds were laid down, the ancient volcanic bank of the cheviots had thus suffered great erosion. this is what "unconformability" means. it points to the prolonged continuance of a land-surface, subject as that must always be to the wearing action of the sub-aërial forces. rain and frost disintegrate the rocks, and running water rolls the débris from higher to lower levels, and piles it up in the form of gravel, sand, and mud in lakes and the sea. while the old volcanic country of the cheviots was being thus denuded, it would appear that a wide extent of land existed in the northern highlands and southern uplands of scotland, and also in what are now the lake districts of england and the hilly tracts of wales. and in all these regions valleys were formed, which at a subsequent time were more or less filled up with newer deposits. the presence of the red beds that sweep round the base of the cheviot hills shows unmistakably that a period of submergence followed these land conditions. all the low grounds of southern scotland disappeared beneath a wide sheet of water, which stretched from the foot of the lammermuirs up to the base of the cheviots, and here and there entered the valleys, and so extended into the hills. this water, however, does not seem to have been that of an open sea; rather was it portion of a great freshwater lake, brackish lagoon, or inland sea. the lowest beds of the red series are merely hardened layers and masses of gravel and rolled shingle, which would seem at first sight to indicate the former action of waves along a sea-beach. there are certain appearances, however, which lead one to suspect that these ancient shingle beds may have had quite another origin. in some places the stones exactly resemble those which are found so abundantly in glacial deposits. they are sub-angular and blunted, and, like glaciated stones, occasionally show striæ or scratches. this, however, is very rarely the case. most of the stones appear subsequently to have been rolled about in water, and in this process they must have lost any ice-markings they may have had, and become smoothed and rounded like ordinary gravel stones. the same appearances may be noted in the glacier valleys of norway and switzerland, where at the present day the glaciated stones which are pushed out at the lower ends of the glaciers are rolled about in the streams, and soon lose all trace of ice-work. it is impossible, however, to enter here into all the details of the evidence which lead one to suspect that glaciers may have existed at this early period among the cheviot and lammermuir hills. in the latter district, the conglomerates occur in such masses and so exactly resemble the morainic débris and ice-rubbish of modern glacial regions, that the late sir a. c. ramsay long ago suggested their ice-origin. let us conceive, then, that when the ancient lake or inland sea of which i have spoken reached the base of the cheviots, glaciers may have nestled in the valleys. streams issuing from the lower ends of these would sweep great quantities of gravel down the valleys to the margin of the lake, and it is quite possible that there might be enough wave-action to spread the gravel out along the shores. it is evident, however, that the main heaps of shingle would gather opposite what were at that time the mouths of glacier valleys; and it is just in such positions that we now meet with the thickest masses of conglomerate. ere long, however, the supposed glaciers would seem to have melted away, and only fine sand and mud, with here and there small rounded stones and grit, accumulated round the shores of the ancient lake. of course, during all this time fine-grained sediment gathered over the deeper parts of the lake-bottom. we have no evidence to show what kind of creatures, if any, inhabited the land at this time; nor do any fossils occur in the red earthy beds to throw light upon the conditions of life that may have obtained in the lake. if glaciers really existed and sent down ice-cold water, the conditions would hardly be favourable to life of any kind; for glacial lakes are generally barren. but the absence of fossils may be due to other causes than this. it is a remarkable fact, that red strata are, as a rule, unfossiliferous, and the few fossils which they do sometimes yield are generally indicative rather of lacustrine and brackish-water, than marine conditions. the paucity or absence of organic remains seems to have been often due to the presence in the water of a superabundance of salts. now this excessive salinity may have arisen in either of two ways. first, we may suppose some wide reach of the sea to have been cut off from communication with the open ocean by an elevation of a portion of its bed; and in this case we should have a lagoon of saltwater, which evaporation would tend to concentrate to such a degree, that by-and-by nothing would be able to live in its waters. or, again, we may have a lake so poisoned by the influx of springs and streams, carrying various salts in solution, as to render it uninhabitable by life of any kind, either animal or vegetable. many red sandstone deposits, as sir a. c. ramsay has pointed out, are evidently lagoon-formations, which is proved by the presence of associated beds of rock-salt, gypsum, and magnesian limestone. they have slowly accumulated in great inland seas or lakes having no outlet, whose waters were subject to evaporation and concentration, although now and then they seem to have communicated more or less freely with the ocean. the red earthy beds of the jed, however, though unfossiliferous, yet contain no trace of rock-salt or magnesian limestone. the only character they have in common with the salt-bearing strata of the new red sandstone of england is their colour, due to the presence of peroxide of iron, which we can hardly conceive could have been deposited in the mud of a sea communicating freely with the ocean. but a quiet lake, fed by rivulets and streams that drained an old volcanic district, is precisely the kind of water-basin in which highly ferruginous mud and sand might be expected to accumulate. such a lake, tainted with the various salts, etc., carried into it by streams and springs (some of which may have been thermal; for, as we shall see presently, the volcanic forces, although quiescent, were yet not extinct), might well be unfitted for either animal or plant, and probably this is one reason why the red earthy beds of the jed are so unfossiliferous. after some time, the physical conditions in the regions under review experienced some further modification. considerable depression of the land supervened, and the waters of our inland sea or lake rose high on the slopes of the cheviots. mark now how the character of the sediment changes. the prevailing red colour has disappeared, and white, yellow, and pale greenish or grey sand begins to be poured over the bed of the lake. even yet, however, ferruginous matter exists in sufficient quantity to tint the sediment red in some places. with the appearance of these lighter-coloured sandy deposits, the conditions seem to have become better fitted to sustain life. fish of peculiar forms, which, like the gar-pike of north american lakes, were provided with a strong scaly armour of tough bone, began to abound, weeds grew in the water, and the neighbouring land supported a vegetation now very meagrely represented by the few remains of plants which have been preserved. in some places fish-scales are found in considerable abundance. they belong to several genera and species which are more or less characteristic of the old red sandstone formation. the most remarkable form was the _pterichthys_, or wing-finned fish. its blunt-shaped head and the anterior portion of its body were sheathed in a solid case of bone, formed by the union of numerous bony scales or plates. two curious curved spine-like arms occupied the place of pectoral fins, and may have been used by the creature in paddling along the bottom of the sea or lake in which it lived. the posterior part of the body was covered with bony scales, but these were not suturally united. other kinds of fish were the _holoptychius_ and _coccosteus_, both of which were, like the pterichthys, furnished with bony scales. the scales of the former overlapped, and had a curious wrinkled surface. the head of the coccosteus was protected by a large bony shield or buckler, and a similar bony armour covered the ventral region. the organic remains of these fish-bearing strata are too scanty, however, to enable us to form any idea of the kind of climate which characterised the district at this long-past period; but if we rely upon the fossils which have been met with in strata of the same or approximately the same age elsewhere, we may be pretty sure the climate was genial, and nourished on the land an abundant vegetation, consisting of ferns, great reeds, and club-mosses, which attained the dimensions of large trees, conifers, and other strange trees which have no living analogues. it seems most likely that when the land sank down in the cheviot district, so as to allow the old lake to reach as it were a higher level, some communication with the outlying ocean was effected. red ferruginous mud would then cease to accumulate, or gather only now and then; the deposits would for the most part be white or yellow, or pale green; and fish would be able to come in from the sea. the communication with the ocean, however, was probably never very free, but liable to frequent interruption. here, then, ends the third great period of time represented by the rocks of the cheviot district. the first period, as we have seen, closed with the deposition of the silurian strata. thereafter supervened a vast lapse of time, not recorded in the cheviots by the presence of any rocks, but represented in other regions by younger members of the silurian system. during this unrecorded portion of past time, the silurian strata of the cheviots were hardened, compressed, folded, upheaved to the light of day, and worn into hills and valleys by the action of the sub-aërial forces. then began the second period of rock-forming in our district. volcanoes poured out successive beds of molten matter and showers of stones and ashes, and so built up the rock-masses of the highest parts of the cheviot hills. these eruptions belong to the old red sandstone age, and form a portion of what we term the lower old red sandstone. after the extinction of the volcanoes, another prolonged period elapsed, which is not accounted for in the cheviots by the presence of any rocks. then it was, as we know, that the great volcanic bank was denuded and worn into a system of hills and valleys. now, since it is evident that the red beds of the jed and other places are also of old red sandstone age, it follows that they must belong to a higher place in the old red sandstone formation than the much-denuded igneous rocks upon which they rest unconformably. the reasonable conclusion seems to be that the denudation or wearing away of the lower old red sandstone igneous rocks of the cheviots was effected during that period which is represented in other districts of scotland by what is called the middle old red sandstone, so that the jed beds will thus rank as upper old red sandstone. [illustration: fig. .--_s_, silurian strata; _i_, cheviot igneous rocks (lower old red sandstone); _r_, upper old red sandstone series; _c_, kelso igneous rocks (lower carboniferous); _d_, lower carboniferous sandstones, shales, etc.] i come now to speak of certain rocks which, although they are developed chiefly beyond the limits of our district, yet require a little consideration before we can complete our account of the geological history of the cheviots. the rocks referred to consist chiefly of old lava-beds, which very closely resemble those of the lower old red sandstone. they appear on the south side of the tweed valley below kelso, whence they extend south-west and west, crossing the river at makerstoun, and sweeping north to form the hills about smailholm, stichill, and hume (fig. ). all to the east of these rocks, the valley of the tweed is occupied by a great thickness of grey sandstones, and grey and blue shales and clays, with which are associated thin cement-stone bands, and occasional coarse sandy limestones called cornstone. these strata rest upon the outskirts of the kelso igneous rocks, and are clearly of later date than these, since in their lower beds, which are often conglomeratic, we find numerous rounded fragments of the igneous rocks upon which the sandstones and shales abut. the latter have yielded a number of fossils, both animals and plants, to which i shall refer presently. in the bed of the teviot near roxburgh, and elsewhere, the kelso igneous rocks are found reposing upon whitish and reddish sandstones, which are evidently the upper members of the red beds of the jed water and other localities. strata closely resembling the grey sandstones and shales of the tweed valley appear among the cheviot hills at the head of the jed water, where they are marked by the presence of thick massive sandstones, which form all the tops of the hills between hungry law and the heights that overlook the sources of the liddel water--the greatest height reached being at carter fell, which is feet above the sea-level. the strata at this place contain some impure limestone and thin seams of coal, while beds of lava and tuff appear intercalated in the series. [illustration: fig. .--section across old volcanic neck. the dotted line above suggests the original form of the volcano; _b_, plug of igneous rock which rose in a molten state and cooled in the vent.] now let us rapidly sum up what seem to be the inferences suggested by these briefly-stated facts. we have seen that the upper old red sandstone began to be deposited in a lake which, as time wore on, probably communicated with the sea, while the land was undergoing a process of depression, so that the area of deposition was thus widely increased, and sediment gradually accumulated in places and at levels which had existed as land when the ancient lake first appeared in the cheviot district. the old lava-beds of kelso show that the volcanic forces, which had long been quiescent, again became active. great floods of molten matter issued from the bowels of the earth, and poured over the bottom of the inland sea. but all the larger volcanoes of this period were confined to the centre of the tweed valley. not a few little isolated volcanoes, however, seem to have dotted the sea-bottom beyond the limits of the kelso area. from these, showers of stones were ejected, and sometimes also they poured out molten matter. their sites are now represented by rounded hills which stand up, more or less abruptly, above the level of the undulating tracts in which they occur (fig. ). among the most marked are rubers law, black law, the dunian, and lanton hill. of course it is only the plugged-up vents or necks that now remain; all the loose ejectamenta by which these must at one time have been surrounded have long since been worn and washed away. at last the kelso volcanoes became extinct, and the little ones also probably died out at the same time. another long period now ensued, during which the inland sea disappeared, and its dried-up bed was subjected to the denuding action of the sub-aërial forces. the volcanic rocks of the kelso district suffered considerable erosion, while the softer sandy strata amongst which they were erupted no doubt experienced still greater waste. ere long, however, the scene again changes; and what is now the vale of tweed becomes a wide estuary, the shores of which are formed at first by the kelso igneous rocks. into this estuary, rivers and streams carry the spoil of the southern uplands, and strew its bed with sand and mud. occasionally ferns and large coniferous trees are floated down, and, getting water-logged, sink to the bottom, where they become entombed in the slowly accumulating sediment. the character of these buried plants shows that the climate must have been genial. they belong to species which are characteristic of the carboniferous system, and we look upon them with interest as the forerunners of that vast plant-growth which by-and-by was to cover wide areas in britain, and to give rise to our coal-seams, the source of so much national wealth. in the waters of the estuary, minute crustaceous creatures called _cyprides_ abounded, and with these was associated a number of small molluscs, chiefly univalves. here and there considerable quantities of calcareous mud and sand gathered on the bed of the estuary, and formed in time beds of cement-stone, and impure limestone or cornstone. how long that condition of things obtained in the tweed valley we cannot tell; but we know that after a very considerable thickness of sediment had accumulated, estuarine conditions prevailed over the south-west end of what is now the cheviot range. this points to a considerable depression of the land. in this same region volcanic action appeared, and streams of lava and showers of fragmental materials were ejected--the remains of which are seen in hungry law, catcleugh shin, and the head-waters of the jed. genial climatic conditions continued; and here and there, along what were either low islets or the flat muddy shores of the estuary, plants grew in sufficient quantity to form masses of vegetation which, subsequently buried under mud and sand, were compressed and mineralised, and so became coal. the only place where these are now met with is on the crest of the cheviots at carter fell. the process of depression still continuing, thick sand gradually spread over the site of the submerged forests. to trace the physical history immediately after this, we must go out of the cheviot district; and it may suffice if i merely state that these estuarine or lacustrine conditions, which prevailed for a long time not only over the tweed and cheviot areas but in various other parts of scotland, at last gave place to the sea. in this sea, corals, sea-lilies, and numerous molluscs and fishes abounded--all pointing to the prevalence of genial climatic conditions. the organic remains and the geological position of the estuarine beds of the tweed and the cheviots--resting as they do upon the upper old red sandstone--prove them to belong to the lower series of the great carboniferous system. it was some time during the carboniferous period that wide sheets of melted matter were forcibly intruded among the old red sandstone and the lower carboniferous strata of the cheviot district; but although these are now visible at the surface, as at southdean, bonchester, etc., they never actually reached that surface at the time of their irruption. they cooled in the crust of the earth amongst the strata between which they were intruded, and have only been exposed to view by the action of the denuding forces which have worn away the sedimentary beds by which they were formerly covered. a very wide blank next occurs in the geological history of the cheviots. we have no trace of the many great systems, comprising vast series of strata and representing long eras of time, which we know, from the evidence supplied by other regions, followed after the deposition of the lower carboniferous strata. the middle and upper carboniferous groups are totally wanting, so likewise is the permian system; and all the great series of "secondary" systems, of which the major portion of england is composed, are equally absent. nay, even tertiary accumulations are wanting. there is one very remarkable relic, however, of tertiary times, and that is a long dyke or vertical wall of basalt-rock which traverses the country from east to west, crossing the crest of the cheviots near brownhart law, and striking west by north through belling hill, by the rule water at hallrule mill, on towards hawick. this is one of a series of such dykes, common enough in some parts of scotland, which become more numerous as we approach the west coast, where they are found associated with certain volcanic rocks of tertiary age, in such a way as to lead to the belief that they all belong to the same period. the melted rock seems to have risen and cooled in great cracks or fissures, and seldom to have overflowed at the surface. indeed it is highly probable that many or even most of the dykes never reached the surface at all, but have been exposed by subsequent denudation of the rocks that once overlaid them. such would appear to have been the case with the great dyke of the cheviot district. we can only conjecture what the condition of this part of southern scotland was in the long ages that elapsed between the termination of the lower carboniferous period and the close of the tertiary ages. it is more than likely that it shared in some of the submergences that ensued during the deposition of the upper group of the carboniferous system; but after that it may have remained, for aught we can tell, in the condition of dry land all through those prolonged periods which are unrecorded in the rocks of the cheviot hills, but have left behind them such noteworthy remains in england and other countries. of one thing we may be sure, that during a large part of those unrecorded ages the cheviot district could not have been an area of deposition. rather must it have existed for untold eras as dry land; and this explains and accounts for the enormous denudation which the whole country has experienced; for there can be little doubt that the lower carboniferous strata of carter fell were at one time continuous with the similar strata of the lower reaches of the tweed valley. yet hardly a trace of the missing beds remains in any part of the country between the ridge of the hills at the head of the jed water and the tweed at kelso. only little patches are found capping the high ground opposite jedburgh, as at hunthill, etc. thus more than a thousand feet of lower carboniferous strata, and probably not less than five hundred or six hundred feet of old red sandstone rocks, have been slowly carried away, grain by grain, from the face of the cheviot district since the close of the lower carboniferous period. iv. in the first of these papers some reference was made to the configuration of the ground in the cheviot district. we have seen that the outlines assumed by the country have been determined in large measure by the nature of the rocks. thus where igneous masses abound, the hills present a more or less irregular, and broken or lumpy contour, while the valleys are frequently narrow and deep. in the tracts occupied by silurian strata, we have, as a rule, broad-topped hill-masses with a smoothly-rounded outline, whose slopes generally fall away with a long gentle sweep into soft green valleys, along the bottoms of which the streams often flow in deep gullies and ravines. where the country is formed of sandstones, and other associated strata, the hills are generally broad and well-rounded, but the outline is not infrequently interrupted by lines of cliff and escarpment. these strata, however, are confined chiefly to the low-grounds, where they form a gently-undulating country, broken here and there, as in dunian hill, bonchester hill, rubers law, etc., by abrupt cones and knobs of igneous rock. it is evident, then, that the diversified character of the cheviot hills and the adjoining low-grounds depends on the character of the rocks and also, as we shall see presently, upon geological structure. each kind of rock has its own peculiar mode of weathering. all do not crumble away under the action of rain, frost, and running water in precisely the same manner. some which yield equally and uniformly give rise to smooth outlines, others of more irregular composition, such as many igneous rocks, break up and crumble unequally in a capricious and eccentric way, and these in the course of time present a hummocky, lumpy, and rough irregular configuration. and as soft and readily-weathered rocks must wear away more rapidly than indurated and durable masses, it follows that the former will now be found most abundantly at low levels, while the latter will enter most extensively into the composition of the hills. but the contour of a country depends not only upon the relative durability of the rocks, but also upon the mode of their occurrence in the crust of the earth. strata, as we have seen, do not all lie in one way; some are horizontal, others are inclined to the horizon, while yet others are vertical. again, many rocks are amorphous; that is to say, they occur in somewhat thick masses which show no trace of a bedded arrangement. such differences of structure and arrangement influence in no small degree the weathering and denudation of rocks, and cannot be left out of account when we are seeking to discover the origin of the present configuration of our hills and valleys. thus, escarpments and the terraced aspect of many hill-slopes are due to inequalities in the strata of which such hills are built up. the softer strata crumble away more rapidly under the touch of the atmospheric forces than the harder beds which rest upon them, and hence the latter are undermined, and their exposed ends or crops, losing support, fall away and roll down the slopes. the igneous rocks of the cheviots are arranged in beds; but so massive are these, that frequently a hill proves to be composed from base to summit of one and the same sheet of old lava. hence there is a general absence of that terraced aspect which is so conspicuous in hills that are built up of bedded rock-masses. here and there, however, the beds are not so massive, several cropping out upon a hill-side; and whenever this is the case (as near yetholm) we find the hill-slopes presenting the usual terraced appearance--a series of cliffs and escarpments, separated by intervening slopes, rising one above the other. in the silurian districts no such terraces or escarpments exist, the general high dip of the strata, which often approaches the vertical, precluding any such contour. in a region composed of highly-inclined greywacké and shale, however, we should expect to find that where the strata are of unequal durability, the harder beds will stand up in long narrow ridges, separated by intervening hollows, which have been worn out along the outcrops of the softer and more easily-denuded beds. and such appearances do show themselves in some parts of the silurian area. as a rule, however, the silurian strata are not thick-bedded, and harder and softer bands alternate so rapidly that they yield on the whole a smooth surface under the action of the atmospheric forces. in the low-lying districts, which, as i have said, are mostly occupied by sandstones and shaly beds, all the abrupt isolated hills are formed of igneous rocks, which are much harder and tougher than the strata that surround them. it is quite evident that these hills owe their present appearance to the durable nature of their constituent rocks, which now project above the general level of the surface, simply because they have been better able to resist the denuding agents than the softer rocks that once covered and concealed them. we see, then, that each kind of rock has its own particular mode of weathering, and that the configuration of a country depends primarily upon this and upon geological structure. indeed, so close is the connection between the geology and the surface-outline of a country, that to a practised observer the latter acts as an unfailing index to the general nature of the underlying rocks, and tells him at a glance whether these are igneous like basalt and porphyrite, aqueous like sandstone and shale, or hardened and altered strata like greywacké. but while one cannot help noticing how in the cheviot district the character of the scenery depends largely upon the nature and structure of the rocks, he shall, nevertheless, hardly fail to observe that flowing outlines are more or less conspicuous over all the region. and as he descends into the main valleys, he shall be struck with the fact that the hill-slopes seem to be smoothed off in a direction that coincides with the trend of these valleys. in short, he cannot help noticing that the varied configuration that results from the weathering of different rock-masses has been subsequently modified by some agent which seems to have acted universally over the whole country. in the upper reaches of the cheviot valleys, the rocks have evidently been rounded off by some force pressing upon them in a direction coinciding with that of the valleys; but soon after entering upon their lower reaches, we notice that the denuding or moulding force must have turned gradually away to the north-east--the northern spurs of the cheviots, and the low-grounds that abut upon these being smoothed off in a direction that corresponds exactly with the trend of that great strath through which flow the teviot and the tweed, from melrose downwards. throughout this broad strath, which extends from the base of the lammermuirs to the foot of the cheviots, and includes the whole of teviotdale, the ground presents a remarkable closely-wrinkled surface, the ridges and intervening hollows all coinciding in direction with the general trend of the great strath, which is south-west and north-east; but turning gradually round to east, as we approach the lower reaches of the tweed. passing round the north-eastern extremity of the cheviot range into northumberland, we observe that the same series of ridges and hollows continues to follow an easterly direction until we near the sea-board, when the trend gradually swings round to the south-east, as in the neighbourhood of belford and bamborough, where the ridges run parallel with the coast-line. the ridges and hollows are most conspicuous in the low-grounds of roxburghshire and berwickshire, especially in the regions between kelso and smailholm, and between duns and coldstream. the dwellers along the banks of the tweed are quite familiar with the fact that the roads which run parallel with the river are smooth and level, for they coincide with the trend of the ridges and hollows; whilst those that cross the country at right angles to this direction must of course traverse ridge after ridge, and are therefore exceedingly uneven. in this low-lying district most of the ridges are composed of superficial deposits of stony and gravelly clay and sand, and the same is the case with those that sweep round the north-eastern spurs of the cheviots by coldstream and ancroft. some ridges, however, consist either of solid rock alone, as near stichill, or of rock and overlying masses of clay and stones. in the hilly regions, again, nearly all the ridges are of rock alone, especially in the districts lying between melrose and selkirk and between selkirk and hawick. indeed, the hills drained by the upper reaches of the teviot and its tributaries are more or less fluted and channelled, as it were--many long parallel narrow hollows having been driven out along their slopes and even frequently across their broad tops. this scolloped and ridged aspect of the hills, however, disappears as we approach the upper reaches of the hill-valleys. from skelfhill pen ( feet) by windburgh hill ( feet), on through the ridge of the cheviot watershed, none of the hills shows any appearance of a uniformly-wrinkled surface. [illustration: fig. .--rounded rocks, with superficial deposits, _t_ _t_ _t_, heaped up against steep faces. the arrows indicate direction followed by the smoothing agent.] a close inspection of the rock-ridges satisfies one that they have been smoothed off by some agent pressing upon them in a direction that coincides with their own trend; and not only so, but the smoothing agent, it is clearly seen, must have come from the watersheds and then pressed outwards to the low-grounds which are now watered by the teviot and the tweed. this is shown by the manner in which the rocks have been smoothed off, for their smooth faces look towards the dominant watersheds, while their rough and unpolished sides point away in the opposite direction. sometimes, however, we find that more or less steeply projecting rocks _face_ the dominant watersheds. when such is the case, there is usually a long sloping "tail" behind the crag--a "tail" which is composed chiefly of superficial deposits. the hills between hume and stichill afford some good examples. the two kinds of appearances are exhibited in the accompanying diagram (figs. , .) the appearance shown in fig. is of most common occurrence in the upland parts of the country, while "crag and tail" (as shown in fig. ) is seen to greatest advantage in the open low-grounds. in both cases it will be observed that superficial deposits (_t_) nestle behind a more or less steep face of rock. [illustration: fig. .--"crag and tail"; boss of hard rock, _c_; intersecting sandstones, _s_; superficial deposits heaped up in rear of crag, _t_. the arrow indicates direction followed by smoothing agent.] when the rocks have not been much exposed to the action of the weather, they often show a polished surface covered with long parallel grooves and striæ or scratches. such polished and scratched surfaces are best seen when the superficial deposits have been only recently removed. often, too, when we tear away the thick turf that mantles the hill-slopes, we find the same phenomena. indeed, wherever the rocks have not been much acted upon by the weather, and thus broken up and decomposed, we may expect to meet with more or less well-marked grooves and stride. now the remarkable circumstance about these scratches is this--they agree in direction with the trend of the rock-ridges and the hollows described above. nor can we doubt that the superficial markings have all been produced by one and the same agent. in the upper valleys of the cheviots, the scratches coincide in direction with the valleys, which is, speaking generally, from south to north, but as we approach the low-grounds they begin to turn more to the east (just, as we have seen, is the case with the ridges and hollows), until we enter england to the east of coldstream, where the striæ point first nearly due east, but eventually swing round to the south-east, as is well seen upon the limestone rocks between lowick and belford. in teviotdale the general trend of the striæ is from south-west to north-east, a direction which continues to hold good until the lower reaches of the tweed are approached, when, as we have just mentioned, they begin to turn more and more to the east. thus it becomes evident that the denuding agent, whatever it was, that gave rise to these ridges and scratched rock-surfaces must have pressed outwards from all the dominant watersheds, and, sweeping down through the great undulating strath that lies between the cheviots and the lammermuirs, must have gradually turned away to the east and south as it rounded the northern spurs of the former range, so as to pass south-east over the contiguous maritime districts of northumberland. a few words now as to the character of the superficial deposits which enter so largely into the composition of the long parallel banks and ridges in the low-grounds of roxburghshire, berwickshire, and the northern part of northumberland. the most conspicuous and noteworthy deposit is a hard tough tenacious clay, which is always more or less well-charged with blunted and sub-angular stones and boulders, scattered pell-mell through the mass. this clay is as a rule quite unstratified--it shows no lines of bedding, and although here and there it contains irregular patches and beds of gravel and sand, yet it evidently does not owe its origin to the action of water. its colour in the upper part of teviotdale and the cheviots is generally a drab-brown, or pale grey and sometimes yellow, while here and there, as in the upper reaches of the jed valley, it is a dark dingy bluish grey. in the lower parts of teviotdale and in the tweed district it is generally red or reddish brown. the stones in the clay have all been derived from the rocks of the region in which it occurs. thus in teviotdale we find that in the higher reaches of the dale which are silurian the stones and boulders consist of various kinds of greywacké, etc. in the lower reaches, however, when we pass into the red sandstone area, we note that the clay begins to contain fragments of red sandstone, while the clay itself takes on a reddish tinge, until we get down to the vale of the tweed, where not only is the clay very decidedly red, but its sandstone boulders also are very numerous. the same appearances present themselves in passing outwards from the cheviots. at first the clay contains only stones that have been derived from the upper parts of the hills, but by-and-by, as we near the low-grounds, other kinds begin to make their appearance, so that by the time we reach the tweed we may obtain from the clay specimens of every kind of rock that occurs within the drainage-area of the teviot and the lower reaches of the river tweed. look at the stones, and you shall observe that all the harder and finer-grained specimens are well-smoothed and covered with striæ or scratches, the best marked of which run parallel with the longer axis of each stone and boulder. these scratches are evidently very similar to those markings that cover the surface of the underlying solid rock, and we may feel sure, therefore, that the denuding agent which smoothed and scratched the solid rocks had also something to do with the stones and boulders of the clay. underneath the stony clay, or _till_, as it is called, we find here and there certain old river gravels. we know that these gravels are river-formations, because not only do they lie at the bottom of the river-valleys, but the stones, we can see, have been arranged by water running in one constant direction, and that direction is always _down_ the valley in which the gravels chance to occur. frequently, however, there is no trace of such underlying gravels, but the till rests directly upon the solid rocks. now what do all these appearances mean? it is clear that there is no natural agent in this country engaged in rounding and scratching the rocks, or in accumulating a stony clay like till. in alpine regions, however, we know that glaciers, as they slowly creep down their valleys, grind and polish and scratch the rocks over which they pass, and that underneath the moving ice one may detect smoothed and striated stones precisely resembling those that occur in till. frost in such alpine regions splits up the rocks of the cliffs and mountain-slopes that overlook a glacier, and immense masses of angular stones and débris, thus loosened, roll down and accumulate along the flanks of the ice-streams. eventually such accumulations are borne slowly down the valley upon the back of the glacier, and are dropped at last over the terminal front of the ice, where they become intermingled with the stones and rubbish, which are pushed or washed out from underneath the ice. these heaps and masses of angular débris and stones are called "moraines," and one can see that in switzerland the glaciers must at some time have been much larger, for ancient moraines occur far down in the low-grounds of that country--the glaciers being now confined to the uppermost reaches of the deep mountain-valleys. moreover, we may note how the mountain-slopes overlooking the present puny glaciers have been rubbed by ice up to a height of sometimes a thousand feet and more above the level of the existing ice-streams. now since the aspect presented by the glaciated rock-surfaces of switzerland is exactly paralleled by the rounded and smoothed rocks of scotland, there can be no doubt that the latter have had a similar origin. again, we find throughout the low-grounds of switzerland a deposit of till precisely resembling that which is so well developed in teviotdale and the valley of the tweed. and as there can be no doubt that the swiss till has been produced by the action of glacier ice, we are compelled to believe the same of the till in scotland. let us further note that in the deep mountain-valleys of switzerland the glacial deposits consist for the most part of coarse morainic débris--of such materials, in short, as the terminal moraines of existing glaciers are mainly composed. not infrequently this morainic débris has been more or less acted upon by the rivers that escape from the glaciers, and the angular stones have been rounded and arranged in bedded masses. it is only when we get out of the mountain-valleys and approach the low-grounds that the till, or stony clay, begins to appear abundantly. the same phenomena characterise the cheviot district. in the upper reaches of the mountain-valleys at the heads of the teviot, the kale, the bowmont, etc., either till does not occur or it is thin and often concealed below masses of rude morainic débris and gravel. out in the low-grounds, however, till, as we have already remarked, is the most conspicuous of all the superficial deposits. from these facts it may be inferred that till indicates the former presence of great confluent glaciers, while morainic débris in hill-valleys points to the action of comparatively small local and isolated glaciers. what, then, are the general conclusions which may be derived from a study of the rock-ridges, flutings, and striæ, and the till of the cheviot district? clearly this: that the whole country has at one time been deeply buried under glacier ice. the evidence shows us that the broad strath stretching between the lammermuirs and the cheviots must have been filled to overflowing with a great mass of ice that descended from the uplands of peebles and selkirk and the broad-topped heights that overlook the sources of the teviot. the cheviots appear to have been quite buried underneath this wide sea of ice, and so likewise were the lammermuirs. at the same time, as we know, all scotland was similarly enveloped in a vast sheet of snow and ice, which streamed out from the main watersheds of the country, and followed the lines of the chief straths--that is to say, the general slope of the ground. the track of the ice in the cheviot district is very distinctly marked. in teviotdale it followed the trend of the valley, and, grinding along the outcrop of the silurian strata, deepened old hollows and scooped out new ones in the soft shaly beds, while the intervening harder strata, which offered greater resistance to the denuding action of the ice, did not wear so easily, and so were rounded off, and formed a series of ridges running parallel to the eroded hollows. the stones and rubbish, dragged along underneath the ice, necessarily increased as the glacier mass crept on its way. the rocks were scratched and grooved by the stones that were forced over them, and the polishing was completed by the finer sand and clay which resulted from the grinding process. wherever a rock projected there would be a tendency for the stones and clay and sand to gather behind it. one may notice the same kind of action upon the bed of a stream, where the sediment tends to collect in the rear of prominent stones and boulders. and we can hardly fail to have observed further that the sediment of a river often arranges itself under the action of the current in long banks, which run parallel to the course of the water. underneath the ice-sheet the stones, sand, and clay behaved in the same way. behind projecting rocks in sheltered nooks and hollows, they accumulated, while in places exposed to the full sweep of the ice-stream they were piled up and drawn out into long parallel banks and ridges, the trend of which coincided with that of the ice-flow. the presence of confused and irregular patches and lenticular beds of sand, clay, and gravel in the till is not difficult to understand when we know that there is always more or less water flowing on underneath a glacier. such streams must assort the débris, and roll angular fragments into rounded stones and pebbles; but the materials thus assorted in layers will ever and anon be crushed up so as to be either partially or wholly obliterated by the slowly moving glacier. as the stones and clay were derived from the underlying rocks, it is no wonder that the colour of the till should vary. in the silurian tracts it is pale yellowish, or bluish grey, and the stones consist chiefly of fragments of silurian rocks, all blunted and smoothed, and often beautifully polished and striated. when we get into the red sandstone region of the low-grounds the colour of the clay begins by-and-by to change, and fragments of red sandstone become commingled with the silurian stones, until ere long the colour of the deposit is decidedly red, and sandstone fragments abound. everywhere the stones show that they have been carried persistently in one direction, and that is _out from the watershed, and down the main valleys_. the direction of the ice-marks upon the solid rocks, and the trend of the "drums," as the parallel ridges of till are termed, show that the ice-sheet of teviotdale and tweed gradually turned away to the east and south-east as it swept round the north-eastern spurs of the cheviots. now we may well ask why the ice did not go right out into the north sea, which is apparently the course it ought to have followed. the same curious deflection affected the great ice-stream that occupied the basin of the forth. when it got past north berwick, that stream, instead of flowing directly east into the north sea, turned away to the south-east and overflowed the northern spurs of the lammermuirs, bringing with it into the valley of the tweed stones and boulders which had travelled all the way from the highlands. it is obvious there must have been some impediment to the flow of the scottish ice into the basin of the north sea. what could have blocked its passage in that direction? at the very time that scotland lay concealed beneath its ice-sheet, norway and sweden were likewise smothered in ice which attained a thickness of not less than five or six thousand feet. the whole basin of the baltic was occupied by a vast glacier which flowed south into northern germany, and this sheet was continuous with glacier-ice that crossed over denmark. when we consider how shallow the north sea is (it does not average more than forty fathoms between scotland and the continent), we cannot doubt that the immense masses of ice descending from norway could not possibly have floated off, but must actually have crept across the bottom of that sea until they abutted upon and coalesced with the scottish ice, so as to form one vast _mer de glace_. thus it was that the scandinavian ice blocked up the path of the scottish glaciers into the basin of the north sea, and compelled them to flow south-east into england.[h] had there been no such obstruction to the passage of the scottish glaciers, it is impossible to believe that snow and ice could ever have accumulated to such a depth in scotland. the scottish ice reached a thickness of some three thousand feet in its deeper parts. it is evident, however, that had there been a free course for the glaciers, they would have moved off before they could have attained this thickness. and we can hardly doubt, therefore, that it was the damming-up of their outlet by the great scandinavian ice-sheet that enabled them to deepen to such an extent in the valleys and low-grounds of scotland. [h] in the extreme north of scotland we find that the scottish ice was, in like manner, compelled to turn aside and overflow caithness from south-east to north-west. when the ice-sheet was at its thickest, the cheviots were completely covered, nevertheless they served to divide the ice-flow between scotland and england, although here and there one finds that the ice passed over some of the lower summits, carrying with it boulders and stones. this is by no means an uncommon circumstance in scotland and other glaciated countries. thus we note that highland boulders have been brought into the vale of the tweed across the lammermuirs; and in the same way boulders from the heights overlooking eskdale have been carried over some of the lower hill-tops into the vale of the teviot. in like manner the swedish ice occasionally overflowed the lower mountain-tops of the dividing ridge or watershed into norway. what wonder now that the cheviot area should exhibit so many flowing outlines, that the hills should be so smoothed and rounded and fluted, that the low-grounds should be cumbered with such heaps of clay and striated stones? long before the great glaciers appeared, the rocks were weathered and worn by the action of the usual atmospheric forces, and each had assumed its own peculiar outline; but how greatly has this been modified by the grinding action of the ice-sheet! to what an extent have projecting rocks been rubbed, and how great is the destruction that has befallen the loose accumulations of river gravel, sand, and clay that gathered in the valleys before the advent of the ice age! all that now remains of these are a few patches preserved here and their underneath the till. the cheviots can tell us nothing of the kinds of plants and animals that clothed and peopled the country in pre-glacial times. all we learn is that streams and rivers flowed as they flow now, and that by-and-by everything was changed, and the land disappeared underneath a vast covering of snow and ice. in my concluding paper i will show how this ice period passed away, and how the present condition of things succeeded. v. i have described the condition of the cheviot district during the climax of the ice age as one of intense arctic cold, the whole ridge of hills being then completely smothered in snow and ice. this excessive climate, however, did not last continuously throughout the so-called glacial period, but was interrupted by more than one mild interglacial epoch. we have evidence in scotland, as in other countries, to show that the great confluent ice-masses melted away so as to uncover all the low-grounds and permit the reappearance of plants and animals. rivers again watered the land, and numerous lakes diversified the face of the country. willows, hazels, and alders grew in the sheltered valleys, oak-trees flourished in the low-grounds, and scots firs clustered upon the hill-slopes. a strong, grassy vegetation covered wide areas, and sedges and rushes luxuriated in marshy places and encroached upon the margins of the lakes. the mammoth, or woolly-coated elephant, roamed over the land, and among its congeners were the extinct ox, the horse, the irish elk, and the reindeer. after such a temperate condition of things had continued for some time--perhaps for thousands of years--the land, during the last interglacial epoch, became gradually submerged to a depth of several hundred feet, and a cold, ungenial sea, in which flourished species of northern and arctic shells, covered the low-grounds of scotland. the cold continuing to increase, our glaciers descended for the last time from the mountains and encroached upon the bed of the sea, until they became confluent, fairly usurping the floor of the german ocean, and pushing back the western seas as far as, and even beyond, the islands of the outer hebrides. there is good reason to believe that such great changes of climate occurred several times during the glacial period, which thus seems to have consisted of an alternation of cold and genial epochs. but as the last phase in this extraordinary series of changes was a cold one, during which great glaciers scoured the face of the country, we now obtain only a few scattered traces of the genial conditions that characterised the preceding mild interglacial epochs. vegetable accumulations, lake and river deposits with mammalian remains, marine beds and their shelly contents, were all ploughed up by the ice, and to a very large extent demolished. here and there, however, we find in the till or boulder-clay that marks the last cold epoch, wasted fragments of trees, tusks of mammoths, and broken sea-shells; while underneath the till we occasionally come upon old lake deposits with vegetable and mammalian remains, or, as the case may be, beds of marine origin well stocked with sea-shells of arctic species. and these freshwater and marine beds repose, in many cases, upon an older accumulation of till, which belongs to an earlier cold epoch of the glacial period. in the cheviot district proper, the traces of mild, interglacial conditions are very slight, but in the immediate neighbourhood we find them more strongly marked. thus, in the valley of the slitrig, near hawick, we notice freshwater beds with peaty matter lying between a lower and an upper till or boulder-clay; and interglacial freshwater beds also appear in the neighbouring county of peebles, particularly in the valley of the leithan water. again, in the valley of the tweed near carham, there occur interglacial beds in which i detected numerous bones of water-rats and frogs. these interglacial remains acquire a peculiar interest when we come to view the "superficial deposits" of scotland in connection with those of england and the continent; for, as i have endeavoured to show elsewhere,[i] it is most likely that the ancient gravels of england, which contain the earliest traces of man, belong for the most part to interglacial times; and the extraordinary changes of climate described above may therefore have been actually witnessed by human eyes. indeed, i believe it was the advent of the last cold epoch of the ice age that drove out the old tribes who used the rude flint implements that are now found in the gravel deposits and caves of england, and who occupied the british area along with hippopotami, rhinoceroses, elephants, lions, hyænas, and other animals. the men who entered britain after the final disappearance of arctic conditions, were more advanced in civilisation, and were accompanied by a very different assemblage of animals--by a group represented by oxen, sheep, dogs, and other creatures, most of which are still indigenous to britain. [i] _great ice age._ but to return to the cheviots. when the final cold epoch had reached its climax, and the ice-sheet began to melt away for the last time, the tops of the hills then once more became uncovered, and large blocks, detached by the action of the frost, fell upon the surface of the glaciers, and were borne down the valleys, some of them to become stranded here and there on hill-slopes, others to be carried far away from the cheviot area and dropped at last over northumberland and durham, or even further south. as the melting of the ice continued, and the glacier of the tweed ceased to reach the sea, great accumulations of gravel and sand were formed. underneath the ice, sub-glacial streams ploughed out the till, and paved their hidden courses with gravel and sand. in summer-time, the whole surface of the tweed glacier was abundantly washed with water, which, pouring down by clefts and holes in the ice, swelled all the sub-glacial streams and rivers. at the same time, floods descending from the lammermuirs and the cheviots, pushed with them vast quantities of shingle, gravel, and sand, part of which was swept upon the surface of the tweed glacier, while much seems to have gathered along its flanks, forming banks and ridges running parallel with the course of the valley. at last the time came when the ice had fairly vanished from the lower reaches of the tweed, and we now walk over its bed and mark the long ridges and banks of shingle and gravel that were formed by the sub-glacial streams and rivers, and the somewhat similar accumulations that gathered along the sides of the glacier at the foot of the lammermuir hills. here and there, also, we note the heaps (_i.e._ moraines) of shingle, earth, clay, and débris, with large erratics which travelled on the surface of the ice, and were dropped upon the ground as that ice melted away. all the loose erratics that lie at the surface in the lower reaches of the tweed valley have come from the west. some of them rest upon hard rock, others upon till, and yet others crown the tops and slopes of gravel and sand hillocks, or appear in low mounds of morainic origin. in the valleys of the cheviot hills one traces the footsteps of the retiring glaciers in mounds and hummocks of rude earthy débris, blocks, and rock-rubbish. these are terminal moraines, and they indicate certain pauses in the recession of the ice. the most remarkable examples occur in the valley of the kale water at blinkbonny, a mile or so above the village of eckford. at that place a bank of morainic matter at one time blocked up the valley of the kale, and thus formed a wide and extensive lake that stretched up to and beyond morebattle. numerous curious hillocks of gravel and sand are banked against the moraine, and point to the action of the flood-waters that escaped from the melting glacier. other gravelly moraine mounds occur higher up the same valley, as near grubbit mill. these last tell us of a time when the kale glacier had retreated still further, so as to have its terminal front near where morebattle now is. wreaths and hummocks of gravel and sand, extending from grubbit to the north-east, along the hollow in the hills that leads to yetholm loch, indicate the course taken by a portion of the torrents that escaped from the ice in summer-time. in other hill-valleys, similar indications of ancient local glaciers may be seen. some of the most conspicuous of these appear upon the slopes and in the high valleys within the drainage-areas of the jed and the kale. they consist chiefly of mounds and hillocks, made up of coarse earthy débris and rock-rubbish; sometimes these are solitary and rest in the throat of a valley, at other times they are scattered all over the hill-slopes and valley-bottom. one can have no doubt as to what they mean: they indicate clearly the presence of insignificant glaciers that were soon to vanish away. the larger and better-defined mounds are true terminal moraines, while the scattered heaps of rubbish point out for us the beds in which the glaciers lay. thus, from the sea-coast up to the highest ridge of this border country, we follow the spoor of the melting ice; passing from massive and wide-spread deposits of till, gravel, and sand, and angular débris in the low-grounds, up to insignificant heaps and scatterings of rock-rubbish and angular boulders at the higher levels of the country. several more or less extensive flats in the hill-valleys indicate the former presence of lakes which have become obliterated by the action of the streams. but by far the most conspicuous example of such silted-up lakes is that of the kale valley, to which reference has already been made. in the later stages of the ice age that river-valley must have existed as a lake from marlfield up to and beyond morebattle. indeed, there is evidence to show that even within historical times a considerable lake overspread the flat grounds in this neighbourhood. the name _morebattle_ is supposed to mean the "village by the lake," and, up to a few years ago, there was a sheet of water called linton loch a little to the east of morebattle. but this has been drained by the proprietor, and is now represented by only two insignificant pools. the present course of the kale between marlfield and kalemouth is of post-glacial age--the old pre-glacial and interglacial course being filled up with drifted materials. as the appearances at this place are somewhat typical of many of the valleys of the cheviot district, i may briefly summarise the history of the morebattle lake. before the advent of the last great age of ice the kale would seem to have flowed from marlfield, close to the line now followed by the turnpike road as far as easter wooden, after which it passed near the present sites of blinkbonny and mosstower, and so on to the teviot, which it joined some little distance above kalemouth. during the ice age many of the old river-courses were completely choked up with clay, stones, and gravel, so that when the ice melted away the rivers did not always or even often regain their old channels. thus, in the case of the kale, we find that the present course of the river below marlfield is of recent or post-glacial age, having been excavated by the river since the close of the glacial epoch. the old or pre-glacial course lies completely choked up and concealed under the rubbish shot into it at a time when glacier-ice filled all the valley of the kale down to marlfield. at this latter place the kale glacier seems to have made a considerable pause--it ceased for some time to retreat--and thus a heavy bank of gravel, sand, shingle, earth, blocks, and angular rubbish gathered in front of it, and obliterated the old river-course into which they were dropped. when the glacier at last disappeared, a lake was formed above the morainic dam that closed the valley below marlfield, and the outflow of the lake took place at a point lying some little distance to the north of the old or pre-glacial course of the kale. by slow degrees the river excavated a new channel for itself in the old red sandstone rocks, and in doing so gradually lowered the level of the waters. this and the silting action of the kale and its feeders slowly converted the lake-hollow into a broad alluvial flat through which the river now winds its way. another extensive lake seems to have occupied the vale of the teviot between jedfoot and eckford, and similar old lake-beds occur in several of the hill-valleys. one good example is seen in the valley of the oxnam water, where the flat tract that extends from the old village of oxnam up to the foot of the row hill indicates the former presence of a lake which has been drained by the stream cutting for itself a gorge in silurian greywackés and shales. in many other valleys it is easy to see that the streams do not always occupy their pre-glacial courses, and some of the old forsaken courses are still patent enough. thus, a glance at the hollow that extends from mossburnford on the jed to hardenpeel on the oxnam is enough to convince one that in pre-glacial, and probably in early post-glacial times also, a considerable stream has flowed from what is now the vale of the jed into the valley of the oxnam. in all the valleys we meet with striking evidence to show that the streams and rivers must formerly have been larger than they are now. certain banks and ridges of gravel fringe the valley-slopes at considerable heights, and indicate the action of deeper and broader currents than now make their way towards the sea. it is probable that these high-level gravel terraces date their existence back to the close of the ice age, when local glaciers still lingered in some of the mountain-valleys, and when in summer-time great floods and torrents descended from the hills. an extremely humid climate seems to have characterised scotland even in post-glacial times, as may be gathered from the phenomena of her peat-mosses. very little peat occurs on the scottish side of the cheviots, and it is conspicuous chiefly on the very crest of the hills, where it attains a thickness that varies from a foot or two up to five or six yards. here and there we detect the remains of birch under the peat, but the peat itself is composed chiefly of bog-moss and heather. the evidence so abundantly supplied by the peat-mosses in other parts of scotland shows that after the ice age had passed away the scottish area became clothed with luxuriant forests of oak, pine, and other trees. at that time the british islands appear to have been joined to themselves and the continent across the upraised beds of the irish sea and the german ocean. races of men who used polished stone implements and sailed in canoes that were hollowed out of single oaks inhabited the country, together with certain species of oxen (now either extinct or domesticated), the elk, the beaver, the wolf, and other animals, such as the dog and the sheep, which are still indigenous. the climate was more excessive then than it is now--the summers being warmer and the winters colder. by-and-by, however, submergence ensued, the great wooded plain that seems once to have extended between britain and the continent disappeared below the waves, and the climate of this country became more humid. the old forests began to decay and the peat-mosses to increase, until by-and-by large areas in the low-grounds passed into the condition of dreary moor and morass, and even the brushwood and stunted trees of the hills died down and became enveloped in a mantle of bog-moss. a study of the present condition of the scottish peat-mosses leads one to believe that the rate of increase is now much exceeded by the rate of decay, and that the eventual disappearance of the peat that clothes hill-tops and valley-bottoms is only a question of time. draining and other agricultural operations have no doubt influenced to some extent this general decay of the peat-mosses; but there is reason to suspect that the change of climate, to which the decay of the peat is due, may really be owing to some cosmical cause. quite recently an accomplished norwegian botanist has come to similar conclusions regarding the peat-mosses of the scandinavian peninsula. we have now traced the geological history of the cheviot district down to the "recent period." from this point the story of the past must be continued by the archæologist, and into his province i will not trespass further than to indicate some of the more remarkable traces which the early human occupants of the upland valleys left behind them. before doing so, however, i may briefly recapitulate the general results we have obtained from our rapid review of the glacial and post-glacial deposits. a study of these has taught us that the cheviot hills and the adjoining low-grounds participated in those arctic conditions under the influence of which all scotland and a large portion of england were buried beneath a wide-spread _mer de glace_. the cheviots themselves were completely smothered under a mass of glacier-ice which extended across the vale of the tweed, and was continuous over the lammermuirs with the vast sheet that filled all the great lowlands of central scotland. but although the cheviots were thus overwhelmed, they yet served to divide the ice-flow, for we find that the gelid masses moved outwards from the hills towards the valley of the tweed, turning gradually away to east and south-east to creep over the north part of england. how far south the ice-sheet reached has not yet been determined, but its _moraine profonde_ or till may be traced to the edge of the thames valley; and i have picked up in norfolk ice-worn fragments of igneous rock, which have been derived from the cheviots themselves, showing that scottish ice actually invaded the low-grounds south of the wash. such severe glacial conditions, after continuing for a long time, were interrupted more than once by intervening periods characterised by a milder and more genial climate. the great _mer de glace_ then melted out of the valleys, and for aught that we can say the snow and ice may even have vanished from the hills themselves. vegetation now covered the country, and herds of the mammoth, the old extinct ox, the irish elk, the reindeer, the horse, and probably other creatures, roamed over the now deserted beds of the glaciers. it was probably at this time that palæolithic man lived in britain. he was contemporaneous with lions, elephants, rhinoceroses, hippopotami, mammoths, reindeer, and other animals of southern and northern habitats, the former living in england when the climate was genial, but being replaced by the northern species when the temperature began again to fall, and snow and glaciers once more reappeared and crept downwards and outwards from the hills. towards the close of the interglacial period the land became submerged to a considerable extent, and species of arctic shells lived over the sites of the drowned land where the mammoth and its congeners had flourished. by-and-by the cold so far increased that another great ice-sheet filled up the shallow sea, and as it slowly ground over the face of the land and the sea-bottom, it scoured out and demolished to a large extent all loose fluviatile, lacustrine, and marine accumulations. when at last the ice melted away, it left the ground cumbered with stony clay, and with much gravel and sand and morainic débris. it is underneath these deposits that we yet obtain now and again fragments of the life of that interglacial epoch. but in all the regions visited by the last great incursion of the _mer de glace_, such relics are comparatively rare; it is only when we get beyond the districts that were overwhelmed that the ancient interglacial remains are well preserved. beyond the southern extremity reached by the latest general ice-sheet--that is to say, in the regions south of the humber, we find the country often sprinkled with tumultuous heaps and wide-spread sheets of gravel and brick-earth, which seem to owe their origin to the floods and torrents that escaped from the melting ice. these waters, sweeping over the land, carried along with them such relics of man and beast as lay at the surface, washing away interglacial river-deposits, and scattering the materials far and wide over the undulating low-grounds of central and eastern england. mr. s. b. j. skertchly, of the geological survey of england, has shown that such is the origin of the so-called "river-gravels" with ancient flint implements and mammalian remains in the districts watered by the little ouse, the waveney, and other rivers in that part of england. these gravels could not possibly have been deposited by the present rivers, for they are found capping the hills at a height of more than eighty feet above the sources of the streams. the whole aspect of the gravels, indeed, betokens the action of rapid floods and torrents, such as must have been discharged abundantly in summer-time from the melting ice-sheet that lay at no great distance to the north. when the ice-sheet vanished away, it left the ground covered thickly in many places with its various deposits. rivers and streams were thus often debarred from their old channels, and were forced to cut out for themselves new courses, partly in drifted materials, and partly in solid rock. a number of lakes then existed which have since been silted up. so long as glaciers lingered in the hill-valleys, the rivers seem to have flowed in greater volume than they now do. by-and-by the bare and treeless country became clothed with a luxuriant forest-growth, and was tenanted by animals, many of which are still indigenous to our country, while others have become locally extinct, such as wolf, beaver, and wild boar. in certain of the old lake-beds of the cheviot district numerous remains of red-deer and other animals have been turned out in the search for marl, and in land drainage and reclamation operations--the red-deer antlers being sometimes of noble dimensions. it seems probable that in early post-glacial times our country was joined to the continent and shared in a continental climate, the summers being then warmer and the winters colder than now. the men who lived in britain after the final disappearance of the great glaciers used stone implements, which were often polished and highly finished, and they sailed in canoes, being probably a race of active hunters and fishers. they belong to the archæologist's "neolithic" or new-stone period--the "palæolithic" or old-stone period being of much older date, and separated, as i believe, from neolithic times by the intervention of the last cold epoch of the ice age. to the forest epoch succeeded a time when the climate became very humid, a result which may have been due in large part to the separation of britain from the continent. it was then that the ancient forests began to decay, and peat-mosses to increase. how long such humid conditions of climate characterised the country we can hardly say, but we know that nowadays our peat-mosses do not grow so rapidly as they once did, and indeed almost everywhere the rate of decay is greater than the rate of increase. this points to a further change of climate, and brings us at once face to face with the present. and now a few words, in conclusion, as to the old camps and other remains that occur so abundantly in the valleys of the cheviot hills. in many of the hill-valleys, especially towards their upper reaches, as in the valleys of the kale and the bowmont, almost every hill is marked by the presence of one or more circular or oval camps or forts. they are generally placed in the most defensible positions, on the very tops of the hills or on projecting spurs and ridges. most of them are of inconsiderable dimensions, and could not have afforded protection to any large number of men, for many hardly exceed one hundred feet in diameter. not a few consist of only a single circular or oval rampart with an external ditch--the rampart being composed of the rude débris which was dug out to form the ditch. others, however, are not only much larger (five to six hundred feet in diameter), but surrounded, in whole or in part, with two or more ramparts separated by intervening ditches; and i have noticed that as a rule the side which must have been most easily assailable was protected by several ramparts rising one above the other. from the extraordinary number of these hill-forts one has the impression that the upper valleys of the cheviots must at one time have been thickly peopled, probably in pre-roman times. it is easy to see that the camps or forts overlooking a valley often bear a certain relation to each other, as if the one had been raised to support the other, and not infrequently we can trace well-marked intrenchments extending across a hill-ridge, or along a hill-slope for a distance of not much short of a mile, and evidently having some strategic connection with the forts or camps in their vicinity. i found no trace of any "dwellings," either near the forts or in the vicinity of the terraces. the only indications of what may have been the walls of such appear within a fortified camp, called the moat hill, at buchtrig. this is an isolated knoll of rock, which has been strongly fortified--large slabs and blocks of the porphyrite of which it is composed having been wedged out with infinite pains to form circular ramparts. the "walls" are of course nearly level with the ground and grassed over, but they indicate little square enclosures, which may very possibly have been huts closely huddled together. this fort is oval, and measures five hundred feet by two hundred and seventy. in the same neighbourhood we also meet with plentiful marks of ancient cultivation and with places of sepulture--all of which may without much doubt be referred to the same period as the camps and forts. the slopes of the hills are often marked with broad horizontal terraces, that remind one strongly of the "lazy-beds" of the hebrides. they are evidently the "cultivated grounds" of the hill-men, and doubtless the hill-slopes were selected for various reasons, chief among which would be their retired and somewhat inaccessible position. the ease with which they could be drained and irrigated would be another of their recommendations; and we must bear in mind that at this early date the low-grounds were covered with forests and morasses, and therefore not so easily cultivated as the hill-slopes. here and there we notice also little conical hillocks or tumuli. they were formerly much more numerous, and by-and-by they will doubtless all disappear. numbers, even within recent years, have been pulled down, partly to clear the ground, and partly for the sake of the stones of which they are composed. this is much to be regretted; for their destruction simply means the obliteration of historical records, the loss of which can never be made good. i asked a farmer what had become of the tumuli which at one time, according to the ordnance survey map, were dotted over the hill behind his house. "if it's the wee knowes (knolls) you mean, i pu'd them down, for they were jist in the way. there was naething o' importance below the stanes, only a wheen worthless bits o' pottery!" and the worthy pointed to a heap of stones behind a neighbouring "dyke," where i afterwards found some fragments of the pottery which had been so ruthlessly demolished. these tumuli are no doubt old burial-places, and much information concerning the habits of our ancient predecessors might often be obtained by a careful examination of the mounds, when it is deemed essential to remove them. but, surely, after all, they might be spared, for they can seldom be so very much "in the way"; and, at all events, if they must be removed, might it not be well to communicate the fact of their approaching demolition to some local archæological society, or to any member of the berwickshire naturalists' club, who for the sake of science would, i feel certain, do what was possible to preserve an accurate account of their contents? "standing-stones" are met with now and again, either singly or in groups, and sometimes they form circles. it is most likely that they were raised by the same people who made the forts and tilled the horizontal "lazy-beds." one can only conjecture that they may have been designed as memorial stones, to mark the place where a chief or person of consequence was slain in battle. they may also mark burial-places, or indicate the site of some deed of prowess or other action or circumstance worthy of being remembered. antiquarians at one time considered that all these stones were relics of druidical worship; but it is needless to say that this view has long been abandoned. that the ancient inhabitants of the cheviots may have had some kind of religion is exceedingly probable, but it must have been of a very primitive kind, not more advanced than that of the north american indians. such are some of the more notable relics of the people who lived in the valleys of the cheviot hills in pre-roman times. these valleys, as i have said, seem to have supported a numerous population, who tilled the slopes and probably hunted in the forests of the adjoining low-grounds. that they lived in fear of foes is sufficiently evident from the number of their intrenchments and fortified camps, to which they would betake themselves whenever their enemies appeared. what effect the roman occupation had on the dwellers among these hills we cannot tell. the great "watling street" passes across the cheviots, and there are some old circular forts and camps quite close to that wonderful road, along which many a battalion of roman soldiers must have marched; and these forts, if of pre-roman age, were not at all likely to have been held by the natives after watling street was made. in the remoter fastnesses of the hills, however, the old tribes may have continued to crop their "lazy-beds," to hunt, and tend their herds, during the roman occupation, and the old forts may have been in requisition long after the last roman had disappeared over the borders. but i have already, i fear, delayed too long over the old history of the cheviot hills, and must now draw my meagre sketches to a close. in my first paper i said that these hills were a _terra incognita_ to the tourist. those who visit the district must not therefore expect to meet with hotel accommodation. but "knowing" pedestrians will not be much disturbed with this information, and will probably find, after they have concluded their wanderings, that the hospitality and general heartiness for which our stalwart borderers were famous in other days are still as noteworthy characteristics as they used to be. v. the long island, or outer hebrides.[j] [j] _good words_, . i. that long range of islands and islets which, extending from latitude ° ' n. to latitude ° ' n., acts as a great natural breakwater to protect the north-west coast of scotland from the rude assaults of the atlantic billows is not much visited by the ordinary tourist. during "the season" the steamers now and again, it is true, deposit a few wanderers at tarbert and stornoway, some of whom may linger for a shorter or longer time to try a cast for salmon in loch laxdail, while others, on similar piscatorial deeds intent, may venture inland as far as gearaidh nah aimhne (garrynahine). others, again, who are curious in the matter of antiquities, may visit the weird standing-stones of callernish, or even brave the jolting of a "trap" along the somewhat rough road that leads from tarbert to rodel, in order to inspect the picturesque little chapel there, and take rubbings of its quaint tombstones with their recumbent effigies of knights, and crusaders' swords, and somewhat incomprehensible latinity. occasionally a few bolder spirits may be tempted by the guide-books to visit barra head, with its ruddy cliffs and clouds of noisy sea-birds, or even to run north to the extremity of the long island to view the wonders of the butt of lewis. but, as a rule, the few summer visitants who are landed at stornoway content themselves with a general inspection of the grounds about sir james mathieson's residence, while those who are dropped at tarbert on saturday are usually quite ready to depart on monday with the steamer that brought them. the fact is that hotel accommodation in the outer hebrides is rather limited, and the means of locomotion through the islands is on the same slender scale. those, therefore, who are not able and willing to rough it had better not venture far beyond tarbert and stornoway. when the islands are first approached they present, it must be confessed, a somewhat forbidding aspect. bare, bleak rocks, with a monotonous rounded outline, crowd along the shore, and seem to form all but the very highest portions of the land that meet our view, while such areas of low-ground as we can catch a glimpse of appear to be everywhere covered with a dusky mantle of heath and peat. but, although the general character of the scenery is thus tame and sombre, yet there are certain districts which in their wild picturesqueness are hardly surpassed by many places in the northern highlands, while one may search the coast-line of the mainland in vain for cliffs to compare with those gaunt walls of rock, against which the great rollers of the atlantic continually surge and thunder. it is wonderful, too, how, under the influence of a light-blue sky, flecked with shining silvery clouds, the sombre peat-lands lighten up and glow with regal purple and ruddy brown. with such a sky above him, and with a lively breeze fresh from the atlantic and laden with the sweetness of clover and meadow-hay and heather-bloom sweeping gaily past him, what wanderer in the outer hebrides need be pitied? and such days are by no means so rare in these islands as many a jaundiced lowlander has maintained. it is true that heavy mists and drizzling rain are often provokingly prevalent, and i cannot forget the experience of a sad-hearted exile, who had resided continuously for a year in lewis, and who, upon being asked what kind of climate that island enjoyed, replied: "sir, it has no climate. there are nine months of winter, and three months of very bad weather." for myself, i can say that my experience of the climate in june, july, and early august of several years has been decidedly favourable. during those months i found comparatively few days in which a very fair amount of walking and climbing could not be accomplished with ease and pleasure, and that is a good deal more than one could venture to say of skye and many parts of the west coast of the mainland. the greatest drawback to one's comfort are the midges, which in these islands are beyond measure bloodthirsty, and quite as obnoxious as the most carnivorous mosquitoes. smoking, and all the other arts and devices by which the designs of these tiny pests are usually circumvented, have no effect upon the hebridean vampires. in the low-grounds especially they make life a burden. but those who have already become acquainted with the ross-shire midges, and yet have preserved their equanimity, may feel justified in braving the ferocity of the hebridean hosts. and if they do so i believe they will be well repaid for their courage. to the hardy pedestrian, especially, who likes to escape from the beaten track laid down in guide-books, it will be a pleasure in itself to roam over a region which has not yet come entirely under the dominion of mr. cook. if he be simply a lover of the picturesque he will yet not be disappointed, and possibly he may pick up a few hints in these notes as to those districts which are most likely to repay him for his toil in reaching them. but if to his love of the picturesque he joins a taste for archæological pursuits, then i can assure him there is a rich and by no means exhausted field of study in the antiquities of the long island. interesting, however, as are the relics of prehistoric and later times which one meets with, yet it is the geologist, perhaps, who will be most rewarded by a visit to these islands. the physical features of the outer hebrides are, as already stated, somewhat monotonous, but this is quite consistent with considerable variety of scenic effect. all the islands are not equally attractive, although the configuration of hills and low-grounds remains persistently the same from the butt of lewis to barra head. the most considerable island is that of which lewis and harris form the northern and southern portions respectively. by far the larger part of the former is undulating moorland, the only really mountainous district being that which adjoins harris in the south. a good general idea of the moorlands is obtained by crossing the island from stornoway to garrynahine. what appeared at first to be only one vast extended peat-bog is then seen to be a gently-undulating country, coated, it is true, with much peat in the hollows, but clad for the most part with heath, through which ever and anon peer bare rocks and rocky débris. now and again, indeed, especially towards the centre of the island, the ground rises into rough round-topped hills, sprinkled sparingly with vegetation. one of the most striking features of the low-grounds, however, is the enormous number of freshwater lakes, which are so abundant as to form no small proportion of the surface. they are, as a rule, most irregular in outline, but have a tendency to arrange themselves in two directions--one set trending from south-east to north-west, while another series is drawn out, as it were, from south-west to north-east. i am sure that i am within the mark in estimating the freshwater lakes in the low-grounds of lewis to be at least five hundred in number. in the mountain-district the lakes are, of course, confined to the valleys, and vary in direction accordingly. harris and the southern part of lewis are wholly mountainous, and show hardly a single acre of level ground. the mountains are often bold and picturesque, especially those which are over feet in height. they are also exceedingly bare and desolate, the vegetation on their slopes being poor and scanty in the extreme. some of the hills, indeed, are absolutely barren. in north harris we find the highest peaks of the outer hebrides: these are the clisham, feet, and the langa, feet. the glens in this elevated district are often wild and rugged, such as the bealach-miavag and the bealach-na-ciste, both of which open on west loch tarbert. but amid all this ruggedness and wild disorder of broken crag and beetling precipice, even a very non-observant eye can hardly fail to notice that the general contour or configuration of the hills is smooth, rounded, and flowing, up to a rather well-marked level, above which the outline becomes broken and interrupted, and all the rounded and smoothed appearance vanishes. the contrast between the smoothly-flowing contour of the lower elevations and the shattered and riven aspect of the harsh ridges, sharp peaks, and craggy tors above, is particularly striking. the mammillated and dome-shaped masses have a pale, ghastly grey hue, their broad bare surfaces reflecting the light freely, while at higher elevations the abundant irregularities of the rocks throw many shadows, and impart a darker aspect to the mountain-tops. the appearances now described are very well seen along the shores of west loch tarbert. all the hills that abut upon that loch show smoothed and rounded faces, and this character prevails up to a height of feet, or thereabout, when all at once it gives way, and a broken, interrupted contour succeeds. thus the top of the tarcall ridge in south harris is dark, rough, and irregular, while the slopes below are grey, smooth, and flowing. the same is conspicuously the case with the mountains in north harris, the ruinous and sombre-looking summits of the langa and the clisham soaring for several hundred feet above the pale grey mammillated hills that sweep downwards to the sea. after having familiarised themselves with the aspect of the hills as seen from below, the lover of the picturesque, not less than the geologist, will do well to ascend some dominant point from which an extensive bird's-eye view can be obtained. for such purpose i can recommend the tarcall and roneval in south harris, the clisham and the langa in north harris, and suainabhal in lewis. the view from these hills is wonderfully extensive and very impressive. from suainabhal one commands nearly all lewis; and what a weird picture of desolation it is! an endless succession of bare, grey, round-backed rocks and hills, with countless lakes and lakelets nestling in their hollows, undulates outwards over the districts of uig and pairc. away to the north spread the great moorlands with their lochans, while immediately to the south one catches a fine panoramic view of the mountains of harris. and then those long straggling arms of the sea, reaching into the very heart of the island--how blue, and bright, and fresh they look! i suppose the natives of the lewis must have been fishermen from the very earliest times. it seems hardly possible otherwise to believe that the bare rocks and peat-bogs, which form the major portion of its surface, could ever have supported a large population; and yet there is every evidence to show that this part of the long island was tolerably well populated in very early days. the great standing-stones of callernish and the many other monoliths, both solitary and in groups, that are scattered along the west coast of lewis, surely betoken as much. and those curious round towers, or places of refuge and defence, which are so well represented in the same district, although they may be much younger in date than the monoliths of callernish, tell the same tale. from the summits of the clisham and the langa the view is finer than that obtained from suainabhal. the former overlook all the high-grounds of harris and lewis, and the monotonous moors with their countless straggling lakes and peaty tarns. indeed, they dominate nearly the whole of the long island, the hills of distant barra being quite distinguishable. of course, the lofty island of rum, and skye with its coolins, are both clearly visible, the whole view being framed in to eastward by the mountains of ross and sutherland. on a clear day, which, unfortunately, i did not get, one should be quite able to see st. kilda. hardly less extensive is the view obtained from roneval ( feet) in the south of harris. far away to the west lie st. kilda and its little sister islet of borerey. southwards stretch the various islands of the outer hebrides--north uist, benbecula, south uist, and barra. how plainly visible they all are--a screen of high mountains facing the minch, and extending, apparently, along their whole eastern margin--with broad lake-dappled plains sweeping out from the foot-hills to the atlantic. in the east, skye with its spiky coolins spreads before one, and north of skye we easily distinguish ben slioch and the mountains of loch maree and loch torridon. south harris lies, of course, under our feet, and it is hard to give one who has not seen it an adequate notion of its sterile desolation. round-backed hills and rocks innumerable, scraped bare of any soil, and supporting hardly a vestige of vegetation; heavy mountain-masses with a similar rounded contour, and equally naked and desolate; blue lakelets scattered in hundreds among the hollows and depressions of the land: such is the general appearance of the rocky wilderness that stretches inland from the shores of the minch. then all around lies the great blue sea, shining like sapphire in the sun, and flecked with tiny sails, where the fishermen are busy at their calling. from what has now been said, it will readily be understood that there is not much cultivable land in harris and the hilly parts of lewis. what little there is occurs chiefly along the west coast, a character which we shall find is common to most of the islands of the outer hebrides. in the neighbourhood of stornoway, and over considerable areas along the whole west coast of lewis, the moorlands have been broken in upon by spade and plough, with more or less success. but natural meadow-lands, such as are frequently met with on the west side of many of the islands both of the outer and inner hebrides, are not very common in lewis. one of the most notable features of the hillier parts of the long island are the enormous numbers of loose stones and boulders which are everywhere scattered about on hill-top, hill-side, and valley-bottom. harris is literally peppered with them, and they are hardly less abundant in the other islands. they are of all shapes and sizes--round, sub-angular, and angular. one great block in barra i estimated to weigh seven hundred and seventy tons. many measure over three or four yards across, while myriads are much smaller. these boulders are sometimes utilised in a singular way. in harris, there being only one burial-place, the poor people have often to carry their dead a long distance, and this of course necessitates resting on the journey. to mark the spot where they have rested, the mourners are wont to erect little cairns by the road-side, many of which are neatly built in the form of cones and pyramids, while others are mere shapeless heaps of stones thrown loosely together. instead of raising cairns, however, they occasionally select some boulder, and make it serve the purpose by canting it up and inserting one or more stones underneath. occasionally i have seen in various parts of the mainland great boulders cocked up at one end in the same way. some of these may be in their natural position, but as they often occupy conspicuous and commanding situations, i am inclined to think that the cromlech-builders may have tampered with them for memorial purposes. the present custom of the harris men may therefore be a survival from that far-distant period when callernish was in its glory. north uist is truly a land of desolation and dreariness. bare, rocky hills, which are remarkable for their sterile nakedness even in the long island, form the eastern margin, and from the foot of these the low, undulating rocky and peaty land stretches for some ten or twelve miles to the atlantic. the land is everywhere intersected by long, straggling inlets of sea-water, and sprinkled with lakes and peaty tarns innumerable. along the flat atlantic coast, which is overlooked by some sparsely-clad hills, are dreary stretches of yellow sand blown up into dunes. near these are a few huts and a kirk and manse. not a tree, not even a bush higher than heather, is to be seen. peat, and water, and rock; rock, and water, and peat--that is north uist. the neighbourhood of lochmaddy, which is the residence of a sheriff-substitute, and rejoices besides in the possession of a jail, is depressing in the extreme. it is made up of irregular bits of flat land all jumbled about in a shallow sea, so that to get to a place one mile in direct distance you may have to walk five or six miles, or even more. i could not but agree with the natives of the more coherent parts of the long island, who are wont to declare that lochmaddy is only "the clippings of creation"--the odds and ends and scraps left over after the better lands were finished. north uist, however, boasts of some interesting antiquities--picts' houses, and a great cairn called the barp, inside of which, according to tradition, rest the remains of a wicked prince of the "good old days." notwithstanding these, there are probably few visitors who will not pronounce north uist to be a dreary island. benbecula is precisely like north uist, but it lacks the bare mountains of the latter. there is only one hill, indeed, in benbecula; all the rest is morass, peat, and water. massive mountains fringe all the eastern shores of south uist, and send westward numerous spurs and foot-hills that encroach upon the "machars," or good lands, so as to reduce then to a mere narrow strip, bordering on the atlantic. save the summits of beinn mhor ( feet) and hecla ( feet), which are peaked and rugged, all the hills show the characteristic flowing outline which has already been described in connection with the physical features of harris. the low-grounds are, as usual, thickly studded with lakes, and large loose boulders are scattered about in all directions. barra is wholly mountainous, and, except that it is somewhat less sterile, closely resembles harris in its physical features, the hills being smoothed, rounded, and bare, especially on the side of the island that faces the minch. of the smaller islands that lie to the south, such as papey, miuley, and bearnarey, the most noteworthy features are the lofty cliffs which they present to the atlantic. for the rest, they show precisely the same appearances as the hillier and barer portions of the larger islands--rounded rocks with an undulating outline, dotted over with loose stones and boulders, and now and again half-smothered in yellow sand, which the strong winds blow in upon them. there is thus, as i have said, considerable uniformity and even monotony throughout the whole range of the outer hebrides. i speak, however, chiefly as a geologist. an artist, no doubt, will find infinite variety, and as he wends his way by moorland, or mountain-glen, or sea-shore, scenes are constantly coming into view which he will be fain to transfer to his sketch-book. the colour-effects, too, are often surprisingly beautiful. when the rich meadow-lands of the west coast are in all their glory, they show many dazzling tints and shades, the deep tender green being dashed and flushed with yellow, and purple, and scarlet, and blue, over which the delighted eye wanders to a belt of bright sand upon the shore, and the vast azure expanse of the atlantic beyond. inland are the heath-clad moors, sprinkled with grey boulders and masses of barren rock, and interspersed with lakes, some of which are starred with clusters of lovely water-lilies. behind the moorlands, again, rise the grim, bald mountains, seamed and scarred with gullies, and in their very general nakedness and sterility offering the strongest contrast to the variegated border of russet moor, and green meadow, and yellow beach that fringe the atlantic coast. all through the islands, indeed, the artist will come upon interesting subjects. a most impressive scene may sometimes be witnessed on crossing the north ford, between north uist and benbecula. at low-water, the channel or sound between these two islands, which is five miles in breadth, disappears and leaves exposed a wide expanse of wet sand and silt, dotted with black rocks and low tangle-covered reefs and skerries. on the morning i passed over, ragged sheets of mist hung low down on the near horizon, half-obscuring and half-revealing the stony islets, and crags, and hills that lay between the ford and the minch. seen through such a medium, the rocks assumed the most surprising forms, sometimes towering into great peaks and cliffs, at other times breaking up, as it were, into low reefs and shoals, and anon dissolving in grey mist and vapour. at other times the thin cloud-curtain would lift, and then one fancied one saw some vast city with ponderous walls and battlements, and lofty towers and steeples, rising into the mist-wreaths that hung above it, while from many points on the benbecula coast, where kelp was being prepared, clouds of smoke curled slowly upwards, as if from the camp-fires of some besieging army. the track of the ford winds round and about innumerable rocks, upon which a number of "natives," each stooping solitary and silent to his or her work, were reaping the luxuriant seaweed for kelp-making. their silence was quite in keeping with the general stillness, which would have been unbroken but for the harsh scream of the sea-birds, as they ever and anon rose scared from their favourite feeding-grounds while we plodded and plashed on our way. the artist who could successfully cope with such a scene would paint a singularly weird and suggestive picture. but, to return to the physical features of the long island, what, we may ask, is the cause of that general monotony of outline to which reference has so frequently been made? at first we seem to get an answer to our question when we are told that the islands of the outer hebrides are composed chiefly of one and the same kind of rock. everyone nowadays has some knowledge of the fact that the peculiar features of any given district are greatly due to the character and arrangement of the rock-masses. for example, who is not familiar with the outline of a chalk country, as distinguished from the contour of a region the rocks of which are composed, let us say, of alternating beds of limestone and sandstone and masses of old volcanic material? the chalk country, owing to the homogeneousness of its component strata, has been moulded by the action of weather and running water into an undulating region with a softly-flowing outline, while the district of composite formation has yielded unequally to the action of time's workers--rains, and frosts, and rivers--and so is diversified with ridge, and escarpment, and knolls, and crags. when, therefore, we learn that the outer hebrides are composed for the most part of the rock called _gneiss_ and its varieties, we seem to have at once found the meaning of the uniformity and monotony. it is true that although pink and grey gneiss and schistose rocks prevail from the butt of lewis to barra head, yet there are some other varieties occasionally met with--thus soft red sandstone and conglomerate rest upon the gneissic rocks near stornoway, but they occur nowhere else throughout the long island. now and again, however, the gneiss gives place to granite, as on the west coast of lewis near carloway; and here and there the strata are pierced by vertical dykes and curious twisted and reticulated veins of basalt-rock. all these, however, hold but a minor and unimportant place as constituents of the islands. gneiss is beyond question the most prevalent rock, and we seem justified in assigning the peculiar monotony of the outer hebridean scenery to that fact. but when we come to examine the matter more attentively, we find that there is still some important factor wanting. we have not got quite to the solution of the question. when we study the manner in which the gneiss and gneissic rocks disintegrate and break up at the sea-coast or along the flanks of some rugged mountain-glen, we see they give rise to an irregular uneven surface. they do not naturally decompose and exfoliate into rounded dome-shaped masses, such as are so commonly met with all through the islands, but rather tend to assume the aspect of rugged tors, and peaks, and ridges. the reason for this will be more readily understood when it is learned that the gneissic rocks of the outer hebrides are for the most part arranged in strata, which, notwithstanding their immense antiquity--(they are the oldest rocks in europe)--and the many changes they have undergone, are yet, as a rule, quite distinguishable. the strata are seldom or never horizontal, but are usually inclined at a high angle, either to north-east or south-west, although sometimes, as in the vicinity of stornoway, the "dip" or inclination of the beds is to south-east. throughout the major portion of the long island, however, the outcrop of the strata runs transversely across the land from south-east to north-west. now we know that when this is the case strata of variable composition and character give rise to long escarpments and intervening hollows--the escarpments marking the outcrops of the harder and more durable beds, and the hollows those strata that are softer and more easily eroded by the action of the denuding forces, water and frost. when the dip of the strata is north-east we expect the escarpments to face the south-west, and the reverse will be the case when the strata incline in the opposite direction. seeing then that the outer hebrides are composed chiefly of gneissic rocks and schists which yield unequally to the weather, and which, in the course of time, would naturally give rise to lines of sharp-edged escarpments or ridges and intervening hollows, with now and again massive hills and mountains showing great cliffs and a generally broken and irregular outline, why is it that such rugged features are so seldom present at low levels, and are only conspicuous at the very highest elevations? the rocks of the outer hebrides are of immense antiquity, and there has therefore been time enough for them to assume the irregular contour which we might have expected. but in place of sharp-rimmed escarpments, and tors, and broken shattered ridges, we see everywhere a rounded and smoothly-flowing configuration which prevails up to a height of feet or thereabout, above which the rocks take on the rugged appearance which is natural to them. by what magic have the strata at the lower levels escaped in such large measure from the action of rain and frost, which have furrowed and shattered the higher mountain-tops? i have said that long lines of escarpment and ridges, corresponding to the outcrops of the harder and more durable strata, are not apparent in these islands. a trained eye, however, is not long in discovering that such features, although masked and obscured, are yet really present. the round-backed rocks are drawn out, as it were, in one persistent direction, which always agrees with the _strike_ or outcrop of the strata; and in many districts one notices also that long hollows traverse the land from south-east to north-west in the same way. such alternating hollows and rounded ridges are very conspicuous in barra and the smaller islands to the south, and they may likewise be noted in most of the larger islands also. looking at these and other features, the geologist has no hesitation in concluding that the whole of the islands have been subjected to some powerful abrading force, which has succeeded to a large extent in obliterating the primary configuration of the land. the rough ridges have been rounded off, the sharp escarpments have been bevelled, the abrupt tors and peaks have been smoothed down. here and there, it is true, the dome-shaped rock-masses are beginning again to break up under the action of the weather so as to resume their original irregular configuration. and, doubtless, after the lapse of many ages, rain and frost will gradually succeed in destroying the present characteristic flowing outlines, and the islands will then revert to their former condition, and rugged escarpments, sharp peaks, and rough broken hummocks and tors will again become the rule. but for a long time to come these grey western islands will continue to present us with some of the most instructive examples of rounded and mammillated rock-masses to be met with in europe. from barra head in bearnarey to the butt of lewis we are constantly confronted by proofs of the former presence of that mysterious abrading power, which has accommodated itself to all the sinuosities of the ground, so that from the sea-level up to a height of feet at least, the eye rests almost everywhere upon bare round-backed rocks and smoothed surfaces. ii. in the preceding article i have described the peculiar configuration of the long island--rounded and flowing for the most part--and have pointed out how that softened outline is not such as the rocks would naturally assume under the influence of the ordinary agents of erosion with which we are familiar in this country. the present contour has superseded an older set of features, which, although highly modified or disguised, and often well-nigh obliterated, are yet capable of being traced, and are, no doubt, the conformation assumed by the rocks under the long-continued action of rain and frost and running water. we have now to inquire what it was that removed or softened down the primal configuration i refer to, and gave to the islands their present monotonous, undulating contour. any one fresh from the glacier-valleys of switzerland or norway could have little doubt as to the cause of the transformation. the smoothed and rounded masses of the outer hebrides are so exactly paralleled by the ice-worn, dome-shaped rocks over which a glacier has flowed, that our visitor would have small hesitation in ascribing to them a similar origin; and the presence of the countless perched blocks and boulders which are scattered broadcast over the islands would tend to confirm him in his belief. a closer inspection of the phenomena would soon banish all doubt from his mind; for, on the less-weathered surfaces, he would detect those long parallel scratches and furrows which are the sure signs of glacial action, while, in the hollows and over the low-grounds, he would be confronted with that peculiar deposit of clay and sand and glaciated stones and boulders which are dragged on underneath flowing ice. having satisfied ourselves that the rounded outline of the ground is the result of former glacial action, our next step is to discover, if we can, in what direction the abrading agent moved. did the ice, as we might have supposed, come out of the mountain-valleys and overflow the low country? if that had been the case, then we should expect to find the glacial markings radiating outwards in all directions from the higher elevations. thus the low-grounds of uig, in lewis, should give evidence of having been overflowed by ice coming from the forest of harris; the undulating, rocky, and lake-dappled region that extends between loch roag and loch erisort should be abraded and striated from south-west to north-east. instead of this, however, the movement has clearly been from south-east to north-west. all the prominent rock-faces that look towards the minch have been smoothed off and rounded, while in their rear the marks of rubbing and abrading are much less conspicuous. it is evident that the south-east exposure has borne the full brunt of the ice-grinding--the surfaces that are turned in the opposite direction, or towards the atlantic, having been in a measure protected or sheltered by their position. the striations or scratches that are seen upon the less-weathered surfaces point invariably towards the north-west, and from their character and the mode in which they have been graved upon the rock, we are left in no doubt as to the trend of the old ice-plough--which was clearly from south-east to north-west. nor is it only the low-grounds that are marked in this direction. ascend suaina ( feet), and you shall find it showing evident signs of having been abraded all over, from base to summit. the same, indeed, is the case with all the hills that stretch from sea to sea between uig and loch seaforth. beinn mheadonach, ceann resort, griosamul, and liuthaid, are all strongly glaciated from south-east to north-west. north and south harris yield unequivocal evidence of having been overflowed by ice which did not stream out of the mountain-valleys, but crossed the island from the minch to the atlantic. a number of mountain-glens, coming down from the forest of harris, open out upon west loch tarbert, and these we see have been crossed at right angles by the ice--the mountains between them being strongly abraded from south-east to north-west. it is the same all over south harris, which affords the geologist every evidence of having been literally smothered in ice, which has moved in the same persistent direction. the rock-faces that look towards the minch are all excessively naked; they have been terribly ground down and scraped, and the same holds good with every part of the island exposed to the south-east. now, the mode in which the rocks have been so ground, scraped, rounded, and smoothed betokens very clearly the action of land-ice, and not of floating-ice or icebergs. the abrading agent has accommodated itself to all the sinuosities of the ground, sliding into hollows and creeping out of them, moulding itself over projecting rocks, so as eventually to grind away all their asperities, and convert rugged tors and peaks into round-backed, dome-shaped masses. it has carried away the sharp edges of escarpments and ridges, and has deepened the intervening hollows in a somewhat irregular way, so that now these catch the drainage of the land and form lakes. steep rocks facing the minch have been bevelled off and rounded atop, while in their rear the ice-plough, not being able to act with effect, has not succeeded in removing the primeval ruggedness of the weathered strata. i have said that the movement of the ice was from south-east to north-west. but a close examination of the ice-markings will show that the flow was very frequently influenced by the form of the ground. minor features it was able to disregard, but some prominent projecting rock-masses succeeded in deflecting the ice that flowed against them. for example, if we study the rocks in north harris, we shall find that the langa and the clisham have served as a wedge to divide the ice, part of which flowed away into lewis, while the other current or stream crept out to sea by west loch tarbert. the langa and the clisham, indeed, raised their heads above the glacier mass--they were islets in a sea of ice. it is for this reason that they and the tarcull ridge in south harris have not been smoothed and abraded, but still preserve their weathered outline. all surfaces below a height of feet which are exposed to the south-east, and which have not been in recent times broken up by the action of rain and frost, exhibit strongly-marked glaciation. but above that level no signs of ancient ice-work can be recognised. we see now why it is that the hill-slopes opposite the minch should, as a rule, be so much more sterile than those which slope down to the atlantic. the full force of the ice was exerted upon the south-east front, in the rear of which there would necessarily be comparatively "quiet" ice. for the same reason we should expect to find much of the rock débris which the ice swept off the south-east front sheltering on the opposite side. neither clay nor sand nor stones would gather under the ice upon the steep rocks that face the minch. the movement there was too severe to permit of any such accumulation. but stones and clay and sand were carried over and swept round the hills, and gradually accumulated in the rear of the ice-worn rocks, just in the same way as gravel and sand are heaped up behind projecting stones and boulders in the bed of a stream. hence it is that the western margin of harris is so much less bleak than the opposite side. considerable taluses of "till," as the sub-glacial débris is called, gather behind the steeper crags, and ragged sheets of the same material extend over the low-grounds. all the low-grounds of lewis are in like manner sprinkled with till. over that region the ice met with but few obstacles to its course, and consequently the débris it forced along underneath was spread out somewhat equally. but wherever hills and peaks and hummocks of rock broke the regularity of the surface, there great abrasion took place and no till was accumulated. thus the position and distribution of this sub-glacial débris or bottom-moraine tell the same tale as the abraded rocks and glacial striæ, and clearly indicate an ice-flow from the south-east. this is still further proved by the manner in which the upturned ends of the strata are frequently bent over underneath the till in a north-westerly direction, while the fragments dislodged from them and enclosed in the sub-glacial débris stream away as it were to the same point of the compass. not only so, but in the west of lewis, where no red sandstone occurs, we find boulders of red sandstone enclosed in the till, which could not have been derived from any place nearer than stornoway. in other words, these boulders have travelled across the island from the shores of the minch to the atlantic sea-board. having said so much about the glaciation of lewis and harris, i need not do more than indicate very briefly some of the more interesting features of the islands further south. i spent some time cruising up and down the sound of harris, and found that all the islets there had been ground and scraped by ice flowing in the normal north-west direction, and sub-glacial débris occurs on at least one of the little islands--harmetrey. but all the phenomena of glaciation are met with in most abundance in the dreary island of north uist. the ridge of mountains that guards its east coast has been battered, and ground down, and scraped bare in the most wonderful manner, while the melancholy moorlands are everywhere sprinkled with till, full of glaciated stones, many of which have travelled west from the coast range. benbecula shows in like manner a considerable sprinkling of till, and the trend of the glacial striæ is the same there as in north uist, namely, a little north of west. there are no hills of any consequence in benbecula, but the highly-abraded and barren-looking mountains that fringe the eastern margin of north uist are continued south in the islands of roney and fuiey, either of which it would be hard to surpass as examples of the prodigious effect of land-ice in scouring, scraping, and grinding the surface over which it moves. south uist presents the same general configuration as north uist, its east coast being formed of a long range of intensely glaciated mountains, in the rear of which ragged sheets and heaps of sub-glacial débris are thrown and scattered over the low, undulating tract that borders the atlantic. no part of either benbecula or north uist has escaped the action of ice, but in south uist that knot of high-ground which is dominated by the fine mountains of beinn mhor and hecla towered above the level of the glacier-mass, and have thus been the cause of considerable deflection of the ice-flow. the ice-stream divided, as it were, part flowing round the north flank of hecla, and part streaming past the southern slopes of beinn mhor. but the ice-flow thus divided speedily reunited in the rear of the mountains, the southern stream creeping in from the south-east, and the northern stream stealing round hecla towards the south-west. the track of this remarkable deflection and reunion is clearly marked out by numerous striæ all over the low-grounds that slope outwards to the atlantic coast. the till, it need hardly be added, affords the same kind of evidence as the sub-glacial deposits of the other islands, and points unmistakably to a general ice-movement across south uist from the minch to the atlantic. the influence which an irregular surface has in causing local deflections of an ice-flow is also well seen in barra, where the striæ sometimes point some ° or °, and sometimes ° and even ° north of west--these variations being entirely due to the configuration of the ground. this island is extremely bare in many places, more especially over all the region that slopes to the minch. the atlantic border is somewhat better covered with soil, as is the case with south uist and the other islands already described. vatersey, saundry, papey, miuley, and bearnarey, are all equally well glaciated; but as they show little or no low-ground with gentle slopes, they have preserved few traces of sub-glacial débris. in this respect they resemble the rockier and hillier parts of the large islands to the north. till, however, is occasionally met with, as for example on the low shores of vatersey bay, and on the southern margin of miuley. doubtless, if it were carefully looked for it would be found sheltering in patches in many nooks and hollows, protected from the grind of the ice that advanced from the south-east. i saw it in several such places in the islet of bearnarey, where the striæ indicated an ice-flow as usual towards the north-west. we have now seen that the whole of the long island has been ground, and rubbed, and scraped by land- or glacier-ice which has traversed the ground in a prevalent south-east and north-west direction. we have seen also that this ice attained so great a thickness that it was able to overflow all the hills up to a height of feet above the sea. it is needless to say that such a mass could not have been nurtured on the islands themselves. they have no gathering grounds of sufficient extent, and if they had, the ice would not have taken the peculiar direction it did. instead of flowing across the islands it would have radiated outwards from the mountain-valleys. where, then, did the ice come from? looking across the minch we see skye and the mountains of the north-west highlands, and those regions, as we know, have also been subjected to extreme glaciation. from the appearances presented by the mountains of ross-shire we are compelled to believe that all that region was buried in ice up to a height of not less than feet--the ice-sheet was probably even as much as feet in thickness. the evidence shows that the under portion of this vast ice-sheet flowed slowly off the country into the minch by way of the great sea-lochs. thus we know that an enormous mass crept down loch carron and united with another great stream stealing out from the mountains of skye, to flow north through the hollows of raasay sound and the inner sound into the minch. so deep was the ice that it completely smothered the island of raasay ( feet high) and overflowed all the lofty trappean table-lands of skye. from the coolins, as a centre-point, another movement of the ice-sheet was towards the south-west, against the islands of rum, cannay, and eigg. further north similar vast masses of ice streamed out into the minch, from loch torridon, gairloch, loch ewe, and loch broom. the direction of the glaciation in the north of skye, which is towards north-west, shows that the glacier-mass which overflowed that area must eventually have reached the shores of the long island. in short, there cannot be a reasonable doubt that the immense sheet of ice that streamed off the north-west highlands must have filled up entirely the basin of the minch, and thereafter streamed across the outer hebrides. but it may be objected that if the outer hebrides were overflowed by ice that streamed from the mainland across the north end of skye, we ought to get many fragments of skye rocks and ross-shire rocks too in the sub-glacial débris or till of lewis and harris, and the north end of north uist. but all such fragments are apparently wanting. true, there are bits of stone like the igneous rocks of skye often met with in the hebridean till, but as veins or dykes of precisely the same kind of rock occur in the long island itself, we cannot say that the stones referred to are other than native. a little reflection will show us, however, that it is extremely improbable indeed that stones derived from skye and the mainland should ever have been dragged on under the ice, and deposited amongst the till of the long island. there is only one part of the whole outer hebrides where we might have anticipated that fragments from the mainland should occur; and there, sure enough, they put in an appearance. but before i attempt to explain the non-occurrence of skye rocks in the till of the outer hebrides, let me show in a few words what the glaciation of the long island, skye, and the north-west highlands teaches us as to the general aspect presented by the ice-sheet. the height reached by the surface of the ice in ross-shire and the long island respectively indicates of course that the main movement was from the mainland. we must conceive of an immense sheet of solid ice filling up all the inequalities of the land, obliterating the glens, and sweeping across the hill-tops; and not only so, but occupying the wide basin of the minch to the entire exclusion of the sea, the surface of the ice rising so high that it overtopped the whole of the outer hebrides, and left only the tips of a few of the higher mountains uncovered. the slope of the surface was persistently outwards from the mainland, and the striation of the long island indicates clearly that the dip or inclination of that surface was towards the north-west. nay, more than this, we are now enabled for the first time to say with some approach to certainty what was the precise angle of that inclination. if we take the upper surface of the ice in ross-shire to have been feet (and it was not less), then the slope between the mainland and the outer hebrides was only feet in the mile, or about in . it is quite possible, however, and even probable, that the actual height attained by the ice-sheet in the north-west highlands was more than feet. i think it may yet turn out to have been feet, and if this were so it would give an inclination for the surface of the ice of about feet in the mile. in either case the slope was so very gentle that to the eye it would have appeared like a level plain. over the surface of this plain would be scattered here and there a solitary big erratic or two, while in other places long trains of large and small angular boulders would stream outwards. all these would be derived from such mountain in skye and the mainland as were able to keep their heads above the level of the ice-flow; while a few also might be dislodged by the frost and rolled down upon the glacier from the tips of the clisham and the langa in harris, and hecla and beinn mhor in south uist. every such block, it is evident, would be carried across the buried hebrides, out into the atlantic in the direction indicated by the glaciation of the long island--that is, towards the north-west. but while the upper strata of the ice doubtless followed that particular course, it is obvious that this could not be the case with the under portion of the great sheet, the path of which would be controlled in large measure by the form of the ground over which the ice moved. the upper strata that overflowed the outer hebrides, as we have seen, were locally deflected again and again by important obstacles, and it is quite certain that the same would take place with the deeper portions of the ice-flow. it is well known that the sea along the inner margin of the long island is very deep. in many places it reaches a depth of feet, and occasionally the sounding-lead plunges down for upwards of feet. it would seem, however, that these great depths did not exist before the advent of the ice-sheet, but that the bottom of the minch along the eastern borders of the long island was then some or feet shallower than now, the floor of the sea having since been excavated in the manner i shall presently describe. it is quite apparent, therefore, that the long ridge of the outer hebrides must have offered an insuperable obstacle to the direct passage of the bottom-ice out to the atlantic. here was a great wall of rock shooting up from the floor of the minch, at a high angle, to a height ranging in elevation from feet to upwards of feet. it is simply impossible that the lower strata of the ice that occupied the bed of the minch could climb that precipitous barricade. they were necessarily deflected, one portion creeping to north-east and another to south-west, but both hugging the great wall of rock all the way. we see precisely the same result taking place in the bed of every stream. let us stand upon an almost submerged boulder, and note how the water is deflected to right and left, and we shall observe at the same time that the boulder, by obstructing the current, forces the water downwards upon the bed of the stream, the result being that a hollow is dug out in front. now, in a similar manner, the ice, squeezed and pressed against the hebridean ridge by the steady flow of the great current that crossed the minch, necessarily acted with intense erosive force upon its bed. hence in the course of time it scooped out a series of broad deep trenches along the whole inner margin of the long island, the amount of the excavation reaching from to feet. similar excavated basins occur in like positions opposite all the precipitous islands of the inner hebrides. wherever, indeed, the ice-sheet met with any great obstruction to its flow, there excessive erosion took place, and a more or less deep hollow was dug out in front of the opposing cliff, or crag, or precipitous mountain. while, therefore, the upper strata of the ice-sheet overflowed the outer hebrides from south-east to north-west, the under portions of the same great ice-flow were compelled by the contour of the ground to creep away to north-east and south-west, until they could steal round the ridge and so escape outwards to the atlantic. this being the case, we have a very simple and obvious explanation of the absence of skye rocks in the till of the long island. one sees readily enough that the sub-glacial débris dragged across the minch would naturally be carried away to south-west and north-east by the "under-tow" or deflected ice. it is quite impossible that any skye fragments or bits of rock from the mainland could travel over the bed of the minch, and then be pushed up the precipitous rock wall of the long island. there is only one place in all the outer hebrides where we might expect to meet with extraneous boulders in the till, and that is in the north of lewis, where the land shelves gently into the sea, and the great rocky ridge terminates. here the under-strata of the ice would begin to steal up upon the land, favoured by its gentle inclination, and in that very place accordingly we meet with a deposit of till in which are found many boulders of a hard red sandstone, and some of various porphyries which are quite alien to the long island. moreover, the till itself in that locality is much more of a clay than the usual sub-glacial débris in other parts of lewis, and contains numerous fragments of sea-shells. all this is quite in keeping with the other evidence. the extreme north end of lewis was overflowed by the under-current that crept up the bed of the minch, hugging the hebridean ridge, and dragging along with it a muddy mass interspersed with the shells and other marine exuviæ that lay in its path, and numerous stones, some of which may have come from skye, while others were derived from the mainland. i have already said enough, perhaps, about the abrasion of the hebrides, but i may add a few words upon the origin of the freshwater lakes. many of these rest in complete rock-basins; others, again, seem to lie partly upon solid rock and partly upon till; while yet others appear to occupy mere shallow depressions in the surface of the till. all of them thus owe their origin to the action of the ice-sheet. as one might have expected, the great majority lie along the outcrop of the gneissic strata, which, as a rule, corresponds pretty closely to the flow of the ice. hence the general trend of the lakes is from south-east to north-west. in many cases in fashioning these rock-basins the ice has merely deepened in an irregular manner previously existing hollows, which are now, of course, filled with water. in not a few places, however, the lakes are drawn out in other directions--this being due usually to changes in the strike or outcrop of the strata. for example, over a considerable district in the south of lewis many lake-hollows extend from south-west to north-east, or at right angles to the direction of the ice-flow. such lakes are usually dammed up at one or both extremities by glacial débris. thus most of the features characteristic of the outer hebrides owe their origin directly or indirectly to the action of that great sheet of ice which swept over the islands during what is called the glacial period. and there is no region in northern europe where the immensity of the abrading agent can be more vividly realised. from a study of the phenomena there exhibited we for the first time obtain a definite idea of the surface-slope, and are able to plumb the old ice-sheet, and ascertain with some approach to accuracy its exact thickness. in the deeper parts of the area, between the mainland and the long island, its thickness was not less than feet. of course this great depth of ice could not have been derived exclusively from the snow that fell on the mountains of the north-west highlands. doubtless the precipitation took place over its whole surface, just as is the case in greenland and over the antarctic continent. the winter cold must have been excessive, but the precipitation necessary to sustain such a mass of ice implies great evaporation; in other words, the direct heat of the sun _per diem_ in summer-time was probably considerably in excess of what it is now in these latitudes. the west and south-west winds must have been laden with moisture, the greater portion of which would necessarily fall in the form of snow. we see something analogous to this taking place in the antarctic regions at the present day. that quarter of the globe has its summer in perihelion, and, therefore, must be receiving then more heat _per diem_ than our hemisphere does in its summer season, which, as every one knows, happens when the earth is furthest removed from the sun. but, notwithstanding this, the summer of the antarctic continent is cold and ungenial--the presence of the great ice-sheet there cooling the air and causing most of the moisture to fall as snow. paradoxical as it may seem, therefore great summer heat is almost, if not quite, as necessary as excessive winter cold for the production and maintenance of a wide continental glacier. iii. when we last took a peep at the outer hebrides we found those luckless islands all but obliterated under an immense sheet of ice extending from the mainland out into the atlantic. how far west the great glacier spread itself we cannot as yet positively say; but if the known slope of its surface between the north-west highlands and the long island continued, as there is every reason to believe it would, then it is extremely probable that the ice flowed out to the edge of the great scottish submarine plateau. here the sudden deepening of the atlantic would arrest its progress and cause it to break up into icebergs. in those old times, therefore, a steep wall of ice would extend all along the line of what is now the edge of the -fathoms plateau. from this wall large tabular masses would ever and anon break away and float off into the atlantic--a condition of things which is closely paralleled at present along the borders of the ice-drowned antarctic continent. by-and-by, however, a great change took place, and the big ice-sheet melted off the long island and vanished from the minch. we read the evidence for this change of climate in certain interesting deposits which occur in considerable bulk at the northern extremity of lewis, and in smaller patches in the eye peninsula of the same island. in those districts the old sub-glacial débris or till is covered with beds of clay and sand in which many marine exuviæ are found--shells of molluscs, entomostraca, foraminifera, etc. they clearly prove, then, that after the ice-sheet had vanished lewis was submerged in the sea to a depth of not less than feet, and they also prove that the temperature of the sea was much the same then as now, for the shells all belong to species that are still living in these northern waters. it is very remarkable that the marine deposits in question seem to occur nowhere else in any part of the long island. we cannot believe that the submergence was restricted to the very limited areas where the shell-beds are met with: it must, on the contrary, have affected a very large portion, if not the whole, of the outer hebrides. why, then, do not we meet with shelly sands and clays, with raised beaches and other relics of the former occupation of these islands by the sea, covering wide areas in the low-grounds? how can we explain the absence of such relics from all those districts which, being much under the level of feet, must necessarily have at one time formed part of the sea-floor? the explanation is not difficult to discover. resting upon the surface of the shell-beds at ness and garabost we find an upper or overlying accumulation of sub-glacial débris or till. at ness this upper till closely resembles, in general appearance, the lower deposit that rests directly upon the rocks. it is a pell-mell accumulation of silty clay, crammed with glaciated stones, amongst which are many fragments of red sandstone and some extra-hebridean rocks, and interspersed through it occur also broken fragments of sea-shells. the marine deposits lying below are usually much confused and contorted, and here and there they are even violently commingled with the upper till. they show, generally, a most irregular surface under that accumulation, and are evidently only the wreck of what they must at one time have been. now the presence of this upper till proves beyond doubt that the intense arctic conditions of climate once more supervened. a big ice-sheet again filled up the basin of the minch and flowed over the long island--its under-tow creeping along the inner margin of the lofty rock-barrier as before, and eventually stealing over the low-ground at the butt, where its bottom-moraine or till was dragged over the marine deposits, and confusedly commingled with them. the upper strata of the ice that streamed across the islands renewed the work of abrasion, and succeeded in scraping away all traces of the late occupation by the sea. if any such now exist they must lie buried under the till that cloaks the low-ground on the western margins of the islands. hence it is that we find not a vestige of shelly beds in any part of the long island which was exposed to the full brunt of the ice-flow. at garabost they have been ploughed through in the most wonderful manner, and only little patches remain. at ness, however, they are more continuous. this is owing to the circumstance that the ground in that neighbourhood is low-lying and offered no obstacle to the passage of the ice out to sea. hence the shell-beds were not subjected to such excessive erosion as overtook them along the whole eastern border of the long island. eventually, however, this later advance of the ice-sheet ceased. the climate grew less arctic, and the great glacier began to melt away, until the time came that its upper strata ceased to overflow the islands. they then passed away to north and south, along the hollow now occupied by the minch, following the same path as the bottom-ice. considerable snow-fields, however, still covered the outer hebrides, and large local glaciers occupied all the mountain-valleys, and, descending to low levels, piled up their terminal moraines. some of these local glaciers appear to have gone right out into the minch, as in south uist, and may have coalesced with the great glacier that still filled that basin. it was during this condition of things that most of the great perched blocks that are scattered so profusely over the islands began to be dropt into their present positions. during the climax of glacial cold, when the upper strata of the ice-sheet streamed across the hebrides, large fragments of rock would certainly be wrenched off and carried on underneath the ice; but as only a few of the hebridean mountain-tops were then exposed, there would be a general absence of such enormous erratics as are detached by frost and rolled down upon the surface of a glacier, and any such superficially-borne erratics would be transported, of course, far beyond the long island into the atlantic. when the ice had ceased to overflow the islands, boulders derived from skye and the mainland would no longer be carried so directly out to the atlantic, but would travel thither by the more circuitous route, which the now diminished ice-sheet was compelled to follow. as the snow and ice melted off the hebrides, the rocks would begin to be exposed to the action of intense frost, and many fragments, becoming dislodged and falling upon _névé_, small local ice-sheets, and glaciers, would be stranded on hill-slopes and sprinkled over the low-grounds, along with much broken débris and rock-rubbish. eventually all the lower-grounds would be deserted by the ice, glaciers would die out of the less elevated valleys, and linger in only a few of the glens that drain the higher mountain-masses. such local glaciers have flowed often at right angles to the direction followed by the great ice-sheet. thus, the ice-markings in the glens that come down from the forest of harris to west loch tarbert, run from north to south, while the trend of the older glaciation on the intervening high-grounds is from south-east to north-west. the morainic rubbish and erratics of this latest phase in the glacial history of the long island may be traced down almost to the water's edge, showing plainly that there has been no great submergence of that region since the disappearance of glacial conditions. this is somewhat remarkable, because along the shores of central and southern scotland we have indisputable evidence to show that the land was drowned to the depth of at least fifty feet in post-glacial times. in the outer hebrides, however, there are no traces of any post-glacial submergence exceeding a dozen feet or so; that is to say, there is no proof that the outer hebrides have been of much less extent than they are now. on the contrary, we have many reasons for believing that they were within comparatively recent times of considerably larger size, and were even in all probability united to the mainland. the abundance of large trees in the peat-mosses, and the fact that these ancient peat-covered forests extend out to sea, are alone sufficient to convince one that the outer hebrides have been much reduced in area since the close of the glacial period. these now bleak islands at one time supported extensive forests, although nowadays a tree will hardly grow unless it be carefully looked after. that old forest period coincided in all probability with the latest continental condition of the british islands--when the broad plains which are now drowned under the german ocean formed part of a great forest-land, that included all the british islands, and extended west for some distance into tracts over which now roll the waves of the atlantic. the palmy days of the great british forests, however, passed away when the german ocean came into existence. the climatic conditions were then not so favourable for the growth of large trees; and in the uplands of our country, and what are now our maritime districts, the forests decayed, and were gradually overgrown by and buried under peat-mosses. the submergence of the land continued after that, until central and southern scotland were reduced to a considerably smaller size than now, and then by-and-by the process was reversed, and the sea once more retreated, leaving behind it a number of old raised beaches to mark the levels at which it formerly stood. the greatest submergence that overtook central and southern scotland in times posterior to the latest continental condition of britain did not exceed fifty feet, or thereabout; and the extreme limits reached by the sea in the period that supervened between the close of the glacial epoch and the "age of forests" was not more than one hundred feet. the outer hebrides, however, were certainly not smaller in post-glacial times than they are now, and we have no evidence to show that after the "age of forests" had passed away the sea rose higher than a dozen feet or so above its present level. now there are only two ways in which all this can be accounted for. either the hebrides remained stationary, or stood at a level higher than now, while the central and southern parts of scotland were being submerged; or else there has been a very recent depression within the hebridean area, which has carried down below the sea all traces of late glacial and post-glacial raised beaches. all we know for certain is, that the only raised beaches in the long island are met with in low maritime regions at only a few feet above the present high-water mark. my own impression is that the whole district has been submerged within comparatively recent times; for if the present coast-line had endured since the close of the glacial period, or even since the last continental condition of britain, i should have expected the sea to have done more than it has in the way of excavation and erosion. in a former article i have spoken of the sand-dunes and sandy flats of the west coast of the long island. these receive their greatest development in north uist, benbecula, and south uist. along the whole western margin of these islands stretch wide shoals and banks of yellow sand and silt, and similar shoals and banks cover the bed of the shallow sounds or channels. in the middle of the sound of harris one may often touch the bottom with an oar, and even run one's boat aground. it is the same in the sound of barra, while, as i have already mentioned, one may walk at low-water from benbecula into the adjacent islands of north and south uist. where does all this sand come from? certainly not from the degradation of the islands by the sea, for the sounds appear to be silting up, and the general appearance of the sandy flats along the west coast indicates that the land is upon the whole gaining rather than losing. i have no doubt at all that this sand and silt are merely the old sub-glacial débris which the ice-sheet spread over the low shelving plateau that extends west under the atlantic to the -fathoms line. that plateau must have been thickly covered with till, and with heaps and sheets of gravel and sand and silt, and it is these deposits, sifted and winnowed by the sea, which the tides and waves sweep up along the atlantic margin of the islands. there are many other points of interest to that i might touch upon, but i have said enough perhaps to indicate to any intelligent observer the kind of country he may be led to expect in the long island. of course the history of the glacial period is very well illustrated in many parts of the mainland, which are much easier of access than the outer hebrides. but these islands contain, at least, one bit of evidence which does not occur anywhere else in britain. in them we obtain, for the first time, data for measuring the actual slope of the ice-sheet. it does not follow, however, that the inclination of the surface towards the atlantic was the same all over the area covered by the ice-sheet. the slope of the sheet that flowed east into the basin of the german ocean, for example, may have been, and probably was, less than that of the hebridean ice-flow. but apart altogether from this particular point, i think there is no part of the british islands where the evidence for the former action of a great ice-sheet is more abundant and more easily read, or where one may realise with such vividness the conditions that obtained during that period of extraordinary climatic vicissitudes, which geologists call the glacial epoch. leaving these old arctic scenes, and coming down to the actual present, no one, i think, can wander much about the outer hebrides without pondering over the fate of the islanders themselves. many writers have asserted that the celt of these rather out-of-the-way places is a lazy, worthless creature, whom we saxons should do our best to weed out. one cannot help feeling that this assertion is unfair and cruel. the fact is, we judge him by a wrong standard. he is by nature and long-inherited habits a fisherman, and has been wont to cultivate only so much land as should suffice for the sustenance of himself and those immediately dependent upon him. in old times he was often enough called upon to fight, wrongly or rightly, and thus acquired that proud bearing which it has taken so many long years of misery to crush out. he is, as a rule, totally unfit for the close confinement and hard work which are the lot of the great mass of our mechanics--does not see the beauty of that, and has rather a kind of contempt for the monotonous drudgery of large manufacturing towns. one of the few situations in town that he cares to fill is that of police-constable. give him a life in the open air, however trying it may be, and he will be quite content if he can make enough to feed himself and family. if the fishing chance to be very profitable he does not, as a rule, think of saving the surplus he has made, but looks forward rather to a spell of idleness, when he can smoke his pipe and talk interminable long talks with his neighbours. no doubt this, judged by our own standard, is all very shocking. why doesn't he put his money in the savings-bank, and by-and-by die and leave it to those who come after him? simply because he is a celt, and not a saxon. of course one knows how it will all end. ere long the unadulterated celt will be driven or improved out of these islands, and will retire to other lands, where, mingling and intermarrying with teutons, he will eventually disappear, but not without leavening the races amongst which he is destined to vanish. and who will take his place in the long island? probably a few farmers, a few shepherds, and a sprinkling of gamekeepers; and it is just possible that a few fishermen also may be allowed to settle down here and there upon the coast. one may see the process going on at present. large tracts that once supported many villages are now quite depopulated. the time will come when somebody in parliament will move for the reduction of the civil service estimates by the amount of the sheriff-substitute's salary, and when the jail at lochmaddy will have nothing higher in the scale of being to imprison than some refractory ram. one may be pardoned for wishing that he could foretell for the islands another fate than this. it is sad to think that a fine race of people is thus surely passing away from amongst us, for, despite all that can be urged against them, they are what i say. the fishermen of lewis and barra are bold, stalwart fellows, whom it would be difficult to peer amongst any similar class of men on the mainland. and all through the island one meets with equally excellent specimens of our kind. many a brave soldier who fought our battles in the great french wars hailed from these outer islands. pity it is that no feasible plan to prevent the threatened scattering of the race has yet been brought forward. some day we may regret this, and come to think that though mutton and wool in the long island are desirable, yet islanders would have been better. [postscript.--on pages . i have described the second general ice-sheet that overflowed the outer hebrides as having eventually become resolved into a series of local ice-sheets and glaciers. subsequent research, however, has since led me to believe that the district ice-sheets and local glaciers referred to were not the direct descendants of the last great ice-sheet. they appear to have come into existence long after that ice-sheet had entirely disappeared. _see_ article x.] vi. the ice age in europe and north america.[k] [k] address to the geological society of edinburgh, . in casting about for a subject upon which to address you this evening, i thought i could hardly do better than give you the result of a comparison which i have recently been able to make between the glacial phenomena of europe and north america. the subject of glaciation seems to be now somewhat worn; but i gather from the fact that writers can still be found who see in our superficial deposits strong evidence of the deluge, that a short outline of what we really do know may not be unacceptable. in the short time at our disposal, it is obvious that i cannot enter into much detail, and that many interesting questions must remain untouched. it will be as well, therefore, that i should at the outset define the limits of the present inquiry, and state clearly what are the chief points to which i wish to direct your attention. my main object, then, will be to bring into prominence such evidence as seems to betoken in a special manner the uniformity of conditions that obtained in the northern hemisphere during the ice age. in other words, i shall confine myself to a description of certain characteristic and representative phenomena which are common to europe and north america, with the view of showing that the physical conditions of the glacial period were practically the same in both continents. the phenomena which might be considered under this head embrace nearly all the facts with which glacialists are familiar, but i purpose restricting myself to three questions only, viz.:-- st. _the extent of glaciation._ nd. _changes of climate during the ice age._ rd. _the results of fluvio-glacial action._ the consideration of these questions, even if it were exhaustive (which it cannot be on this occasion), would still leave the general subject very incomplete, for we must forego the discussion of all such interesting topics as the "connection between glaciation and submergence," "the formation of rock-basins," and the "origin of the geographical distribution of our faunas and floras." confining my inquiry within the limits just specified, i shall begin by sketching broadly the general results obtained by glacialists in europe, and thereafter i shall proceed to give an outline of the corresponding conclusions arrived at by american observers. i. _the extent of glaciation in europe._ to what extent, then, let us ask, has europe been glaciated? what areas have been covered with perennial snow and ice? owing to the fulness and clearness of the evidence, we are able to give a very definite answer to this question. it is hardly too much to say that we are as well acquainted with the distribution of glacier-ice in europe during the ice age as we are with that of existing snow-fields and glaciers. the nature of the evidence upon which our knowledge is based is doubtless familiar to many whom i have the pleasure of now addressing, but for the sake of those who have not such familiarity with the subject i may be allowed to indicate very briefly its general character. a rock-surface over which ice has flowed for any considerable time exhibits either an abraded, worn, and smoothed appearance, or the rocks are disrupted and broken, and larger or smaller fragments are found to have been removed and carried forward in the direction followed by the ice. now, ice-worn and shattered rock-surfaces of this description, such as can be seen underneath existing glaciers, occur more or less abundantly over vast regions in europe. they are met with from the north cape south as far as leipzig, and from the outer hebrides east to the valley of the petchora and the foot-slopes of the ural mountains. nor are they confined to northern europe. they appear again and again in france and spain and italy, and in the low-grounds of middle europe, where they occupy positions now far removed from the influence of glacial action. such ice-worn and disrupted rock-surfaces not only prove that glacier-ice formerly covered large portions of our continent, but they also indicate for us the directions in which that enveloping ice moved. the smoother surfaces in question are very frequently marked with coarse and fine parallel scratches and grooves of precisely the same nature and origin as the scratches and grooves which characterise the rocky bed of a modern glacier. and these markings, having been produced by the sand, grit, and stones which are pushed and dragged over the rocks by flowing ice, necessarily discover for us the path of glacial movement. but all rocks subjected to glacial action are not necessarily smoothed and polished. sometimes, owing to structural peculiarities, and for various other reasons, rocks cannot resist the pressure of the ice, but are crushed and broken, and the resulting fragments are rolled and dragged forward in the direction of ice-flow. in this manner the path of a glacier becomes strewed with débris which has from time to time been forced from its rocky bed. there is really no mystery, therefore in tracking the spoor of extinct glaciers; for we have two sets of facts to aid us, either of which might suffice to indicate the extent and direction of glaciation. consider, however, for a moment, what one observes in connection with rock-striation. we have, in the first place, the rounding and smoothing, and the parallel ruts and striæ. not only so, but we frequently find that one side of prominent projecting knolls and hills is more highly worn and abraded than the other. often, indeed, one side may show no trace whatsoever of abrasion. here, again, we have clear evidence of the direction of ice-flow. who can doubt that the worn and abraded rocks look towards the point whence the ice came, and that the non-glaciated rocks in the rear have been sheltered by the rocks in front? it is for this reason that in the mountainous regions of northern europe the striated and smoothed rock-surfaces invariably look up the valleys, while the broken and unworn rock-ledges face in the opposite direction. once more, note the manner in which the sub-glacial rock-rubbish, consisting of clay, sand, grit, stones, and boulders, has been amassed. in places where the ice must have moved more or less rapidly, as on considerable slopes, no accumulation took place, while in the rear of projecting crags and knobs of rock, sub-glacial materials often gathered deeply. again, over low-lying tracts, where the motion of the ice would necessarily be retarded, clay, sand, and stones tended to collect. and this particularly appears to have been the case in those regions where the slow-creeping and gradually thinning ice-sheet approached its terminal line. hence it is that we encounter such thick and wide-spread sheets of sub-glacial detritus upon the undulating low-grounds and plains of southern sweden, denmark, schleswig-holstein, holland, northern germany, poland, and russia. the sub-glacial débris to which i specially refer is known as _till_ or _boulder-clay_ in this country, as _krosstenslera_ in sweden, as _geschiebelehm_ or _geschiebemergel_ in germany, and as _grundmoräne_ or _moraine profonde_ in switzerland. its general characters are too well known to require more than the briefest summary. in general this peculiar accumulation is an unstratified clay, containing, scattered higgledy-piggledy through it, stones and boulders of all shapes and sizes. many of these rock-fragments are smoothed and striated, and even the smallest particles, when viewed under the microscope, often show delicate scratches. frequently, too, the clay is excessively hard and tough, and in many places it shows a kind of pseudo-lamination, which is generally more or less crumpled, and often highly involved. these appearances prove that the clay has not only been subjected to intense pressure, but has actually been rolled over upon itself. i need only refer to the plentiful occurrence of "slickensides" in such clays--the joints by which the clay is often traversed showing such polishing clearly on their faces. these, and many other facts which time forbids me to mention, have received an explanation which has now been generally adopted by european glacialists. the boulder-clay or till is considered by them to represent the ground- or bottom-moraine of glacier-ice. there used to be a notion prevalent amongst geologists in our country that this clay was almost peculiar to these islands. it occurs, however, in most countries of europe. vast regions in the north are more or less continuously covered by it, and we meet with it abundantly also upon the low-grounds of switzerland, from which it may be followed far down the great valley of the rhone into the sunny plains of france. the lower valleys of the pyrenees and other spanish ranges show it well, and it is conspicuous likewise in northern italy, especially over the low tracts at the mouths of the great lake-valleys. in all those places one can see boulder-clay of as pronounced a character as any to be met with in scotland. danish, dutch, german, and russian geologists have of late years devoted much attention to the study of this clay, which is so remarkably developed in their respective countries. it has been long well known that a large proportion of the stones and boulders contained in the till are of northern derivation, but it is only of recent years that we have ascertained the particular routes by which those wanderers or erratics have travelled. the rock-fragments in question have been tracked back, as it were, to their parent masses, and thus, partly in this way, and partly by the evidence of ice-worn surfaces, we have been enabled to follow the spoor of the great northern ice-sheet in a most satisfactory manner. let one or two examples suffice. boulders derived from lapland and finland occur in the till at st. petersburg, and have been traced south-east to moscow. again, fragments carried from gottland, in the baltic, are met with in the boulder-clay of east prussia, and have been followed south to beyond berlin. in like manner boulders of well-known scanian rocks appear in the boulder-clay of leipzig. so also swedish and norwegian rock-fragments are seen in the boulder-clay of denmark, hanover, and holland. very wide areas in northern germany are covered with an almost continuous sheet of glacial detritus, so that it is only occasionally that the underlying rocks crop out at the surface. striated rock-surfaces are therefore by no means so commonly exposed as in regions like the lowlands of scotland. they are not wanting, however, and their evidence is very striking. thus, in the neighbourhood of leipzig and dresden, we find glacial striæ impressed upon certain highly-abraded and ice-worn hillocks of porphyry, the striæ being the work of ice which flowed into saxony from the north. similar striæ;, having a general southerly trend, occur at rüdersdorf, near berlin, at gommern, near magdeburg, at velpke in brunswick, at osnabrück in hanover, and at other places. again, we encounter remarkable evidence of the powerful pressure exerted by the ice in the displacement and removal of huge blocks of strata. in saxony, for example, the tertiary strata are turned up, pushed out of place, and involved in boulder-clay to such an extent that the brown coals have often been mined for in this strange position. witness also the extensive displacements and dislocations of the cretaceous formation in the danish islands of the baltic. so great are the contortions and displacements of the chalk in moen, that these disturbances were formerly attributed to subterranean action. along the north-east coast of that island, cliffs feet in height exhibit the cretaceous beds thrown upon end, twisted, bent, and even inverted, boulder-clay being squeezed into and between the disjointed and ruptured rock-masses. from a study of these and similar phenomena, it has been demonstrated that during the climax of the ice age a very large part of northern europe was buried under a thick covering of glacier-ice. and it has been conclusively shown that this ice-sheet streamed outwards in all directions from the high-grounds of scandinavia, for which reason it is often spoken of as the scandinavian ice-sheet. but as it was fed, not from the snow-fields of scandinavia alone, but from the precipitation of snow over its whole surface, it is better, i think, to speak of it as the northern ice-sheet. in the extreme north of scandinavia the ice flowed northward into the arctic ocean, while south of the dominant watershed of lapland and sweden its course in those high latitudes was east and south-east. it filled up the depressions of the white sea, the gulf of bothnia, and the baltic, extending east to the valley of the petchora and the base of the ural mountains, and south-east to kazan, some miles east of nijnii-novgorod. from this point its terminal front trended a little west of south, until it reached the fiftieth parallel of latitude. undulating a few miles south and north of this parallel, it swept directly west through russia into galicia, till it touched the foot-hills of the carpathian range. after this we follow it along the northern base of the riesen gebirge, the erz gebirge, and the harz, and thence westward through hanover, and into the low countries, as far south at least as the mouth of the rhine. throughout the vast regions lying west and north of this terminal line, the track followed by the ice has been well ascertained. it was east and south-east in russia, southerly in east prussia, south-westerly in denmark, hanover, and holland. the action of a mass of glacier-ice, reaching a thickness of several thousand feet, must necessarily have resulted in extensive erosion of the rocks over which it passed. everywhere, therefore, throughout the vast area just indicated, we meet with evidence of severe erosion. but, as one should expect, such erosion is most marked in the hilly regions--in those areas where steep slopes induced more rapid motion of the ice, and where projecting crags and hills opposed the advance of the eroding agent. all such prominent obstructions were energetically assailed--abraded, rounded, worn, and smoothed, or crushed, shattered, dislocated, and displaced. the high-grounds of scandinavia and finland, formed for the most part of tough, crystalline rocks, or of more or less durable strata, show everywhere _roches moutonnées_--smoothed and rounded rocks--while innumerable rock-basins have been scooped out in front of prominent crags and hills. in denmark and other countries, where less durable rocks prevail, the strata have often been broken and disrupted, and pushed out of place. but as regions formed of such rocks are generally gently-undulating, and seldom show abrupt crags and hills, they oppose few obstructions to the advance of an ice-sheet. when the northern ice-sheet flowed into russia and germany, it crept over a low-lying and, for the most part, gently-undulating surface; and although here and there the form of the ground favoured glacial erosion and disruption, and extensive displacements of rock-masses took place, yet, upon the whole the low-lying regions referred to became areas of accumulation. the sub-glacial detritus--ground out or wrenched away from the rough scandinavian plateau and the uplands of finland--was dragged on underneath the ice, and spread over the great plains lying to the south-east and south, as the gradually attenuated ice-sheet crawled to its terminal line. my friend dr. amund helland, the well-known norwegian geologist, has made an estimate of the amount of rock-débris derived from scandinavia and finland which lies scattered over the low-grounds of northern europe. according to him, the area in denmark, holland, germany, and russia (exclusive of finland), over which northern detritus is scattered, contains about , , square kilometres, and the average thickness of the deposits is about feet, of which, however, only two-thirds, or feet, are of northern origin, the remaining third consisting of local materials. taking, then, feet as fairly representing the average thickness of the rock-rubbish derived from finland and scandinavia, the area of which is given as , square kilometres, there is enough of this material to raise the general surface of those lands by feet. the same amount of material would suffice to fill up all the numerous lakes of finland and sweden sixteen or seventeen times over. or, if tumbled into the baltic, it would fill the basin of that sea one and a half times. in short, enough northern rock-débris lies upon the low-grounds of northern europe, which, were it restored to the countries from which it has been taken, would obliterate all the lake-hollows of finland and sweden, raise the level of those lands by feet, and fill up the entire basin of the baltic, with all its bays. and yet this estimate leaves out of account all the material which the ice-sheet carried away from norway and the british islands. of the glaciation of our own land i need say very little. the configuration of our country necessarily made it a centre of dispersion during the ice age, and the ice which covered ireland, scotland, and the major portion of england radiated outwards from the dominant elevations of the land. but as the ice creeping outwards from those centres became confluent, the directions which it followed were often considerably modified, especially upon the low-grounds. we know that the british ice-sheet not only covered the land up to near the tops of our higher mountains, but filled up all our seas and extended into the atlantic beyond the coasts of ireland and the outer hebrides--these latter islands having been glaciated from the east by the ice that flowed outwards from the mainland. another point upon which we are now well assured is the fact that the british and scandinavian ice-sheets coalesced, so that the basin of the north sea completely brimmed over with glacier-ice. finally, then, in contemplating the physical conditions that obtained in northern europe at the climax of the ice age, we have to picture to ourselves the almost total obliteration under a vast ice-sheet of all the land-features of the british islands, scandinavia, and finland, and the adjacent low-lying tracts of denmark, holland, germany, poland, and russia. if at that distant date a prehistoric man could have stood on the summit of snaehatten, he would have seen an apparently interminable plain of snow and ice, bounded only by the visible horizon. could he have followed the plain southwards in hopes of escaping from it, he would have descended its gently-sloping surface by imperceptible gradations for a distance of miles, before he reached its termination at the foot of the mountains of middle germany. or, could he have set out upon an easterly course, he would have crossed the gulf of bothnia, buried several thousand feet beneath him, and touched the foot-slopes of the ural mountains before he gained the terminal front of the ice-cap, a distance of miles. on the other hand, had he walked south-west in the direction of ireland, he would have traversed the area of the north sea at a height of several thousand feet above its bed, and, crossing the british area, would only have reached the ice-front at a point some miles beyond the coast of ireland. here he would have seen the ice-sheet presenting a steep face to the assaults of the atlantic, and breaking away in massive tabular bergs, like those which are calved by the ice-cap of the antarctic regions. i must now pass rapidly in review the facts relating to the glaciation of the mountainous regions which lay outside of the area covered by the northern ice-sheet. the glaciers of the alps of switzerland, about which so much has been written, and the study of which first gave venetz, charpentier, and agassiz the clue to the meaning of striated rocks, boulder-clay, and erratics, are, as is well known, the puny descendants of former gigantic ice-flows. at the culmination of the ice age all the mountain-valleys of switzerland and northern italy were choked with glaciers that streamed out upon the low-grounds. along the northern slopes of the alps, as in bavaria and würtemberg, these glaciers coalesced to form a considerable ice-sheet, and so likewise did the glaciers that descended from switzerland, savoy, and dauphiny, into the great valley of the rhone. even in north italy the same was the case with the glaciers that occupied the valleys in which now lie lakes orta, maggiore, varese, lugano, and como--the united ice-flows of those valleys forming a glacier which deployed upon the plains of the po, with a frontage of not less than miles. to the north of the alps, the vosges mountains and the black forest, the harz, the erz gebirge, the riesen gebirge, and the böhmer-wald--all had their perennial ice and glaciers, although none of those elevated tracts now reaches the snow-line. it was the same with the carpathians and the urals, amongst which we meet with relics of much larger ice-streams than any that now exist in the alps. considerably further south were the glaciers of the despoto dagh of roumelia. great glaciers also in former times descended from the caucasus, and in many hilly regions of asia minor indubitable traces of similar large ice-flows have been detected. the high-grounds of central france, and the mountains of beaujolais and lyonnais supported considerable glaciers, while from the pyrenees numerous glaciers of the first class flowed out upon the low-grounds of france, and considerable ice-streams occupied the mountain-valleys on the spanish side. other peninsular chains--the serra da estrella, the sierra guadarama, and the sierra nevada--had likewise their snow-fields and ice-streams. the same was the case with the apennines and the apuan alps of italy, the traces of former glacial action being conspicuous over a considerable part of tuscany. even in corsica we encounter the same evidence of glaciation--striated rock-surfaces and moraines--which point to the former descent of considerable glaciers from monte rotondo. but rock-striæ and moraines are not the only proofs of former cold and humid conditions having prevailed over middle and southern europe at the climax of the glacial period. the limestone-breccias of gibraltar have been described by professor ramsay and myself, and we have shown that these could only have been formed under the influence of excessive frost and melting snows. the limestone of the rock has been broken up along the ridge, and its fragments showered down the slopes, at a time when these were more or less thickly covered with snow. resting upon and imbedded in this snow, the rock-rubbish would be carried downward and outward during the gradual melting that took place in summer. and in this way immense accumulations of débris were borne forwards over the low-grounds that extended from the base of the rock into regions which are now partially submerged. breccias which have probably had a similar origin occur also in corsica, malta, and cyprus, and doubtless they will yet be recognised in many other places. again, over wide areas in northern france and the south of england, we meet with extensive sheets of earthy clay and rock-rubbish, which have certainly been heaped up under very different conditions of climate than obtain now. this stony earth has evidently travelled down the gentle slopes of the land, under the influence of frost and melting snow, in much the same way as ice-driven rock-rubbish and soil move slowly down the slopes of such dreary regions as patagonia and certain low-lying tracts within the arctic circle. ii. _changes of climate in europe during the ice age._ we come next to the very interesting question of alternations of climate during the ice age. the evidence under this head has accumulated to such an extent within recent years as to convince most students of pleistocene geology that very extensive changes of climate characterised the glacial period. how many such changes took place we are not yet in a position to say, but we know that the intensely arctic condition of things which has just been described was interrupted more than once by what have been termed "interglacial epochs," during which a mild and genial climate prevailed over middle and northern europe. for some time it was believed that such "interglacial epochs" had only a local significance, that they bespoke mere transitory retreats of the ice-fields, such as are known to have taken place within historical times in the glacier-valleys of the alps. but increased observation and reflection have shown that this explanation of the phenomena of "interglacial beds" will not suffice. it is impossible to enter here upon details, but i may briefly state that the evidence in question is two-fold. _first_, we have the stratigraphical evidence. we have ascertained the existence, over wide areas in this and other glaciated countries, of several successive sheets of boulder-clay, which are often separated from each other by fossiliferous aqueous strata. it has been demonstrated that each of these sheets of sub-glacial detritus is the accumulation of a separate and distinct ice-flow. _second_, we have the evidence of fossil organic remains. we find, for example, that the flora which covered the low-grounds of middle and temperate europe during a certain stage of the glacial or pleistocene period, consisted of plants which are now restricted to the tops of our mountains and to northern scandinavia. the characteristic fauna associated with that flora embraced the reindeer, glutton, mammoth, woolly rhinoceros, arctic fox lemming, chamois, and so forth. we know, indeed, that man hunted the reindeer and the mammoth in the south of france. similar testimony to the coldness and humidity of the climate is borne by the land- and freshwater shells which occur in certain pleistocene deposits in italy, corsica, southern france, switzerland, germany, etc. that this flora and fauna were contemporaneous with the great glaciation of our continent has been as well ascertained as the fact of the roman occupation of britain. but if the evidence of organic remains strongly confirms and supports that supplied by the distribution of glacial deposits in europe, no less forcibly does it corroborate the physical evidence as to the former existence of a warm and genial interglacial climate. during interglacial times a most abundant mammalian fauna roamed over all temperate europe--a fauna comprising such animals as irish deer, urus, bison, horse, stag, saiga, brown bear, grisly bear, several species of elephant, rhinoceros, and hippopotamus, hyæna, lion, leopard, etc. a like tale of genial conditions is told by the land- and freshwater shells, which occur in some of the pleistocene deposits of england, france, belgium, germany, switzerland, and italy. the testimony of the associated flora is just as striking. how genial and equable must have been the climate which permitted plants like the canary laurel, the judas-tree, the fig-tree, and others to flourish side by side in the north of france, with such forms as the hazel, willow, ash, and sycamore! the most noteworthy additions to our knowledge of interglacial conditions which have recently been made are the results obtained by m. gaudry in the valley of the seine, and by dr. penck in bavarian tyrol, the latter of whom has shown that there have been at least three great advances of the alpine glaciers, separated by long-continued mild conditions, during which the glaciers receded far into the mountains. it is interesting to observe that we have, especially in our own islands, good evidence to show that during the glacial period considerable oscillations of the relative level of land and sea took place. thus, it has been ascertained, that just before the latest epoch of extensive glaciation, the british islands were largely submerged in the sea. to what depth this remarkable submergence was carried we do not know, because any marine deposits which may have been accumulated at that time over the drowned country were for the most part obliterated by the action of the ice-sheet which subsequently covered and reglaciated our lands.[l] but the few fragments of such marine deposits as have been preserved show us that the depression reached more than feet in scotland (_i.e._, measured from the present sea-level), and exceeding feet in wales and ireland. we note, then, in passing, that the only great pleistocene submergence of these lands of which geologists have any knowledge took place before the appearance of the last general ice-sheet that overflowed our low-grounds. the submergences of a later date were of inconsiderable importance, hardly exceeding feet or thereabouts below the present sea-level. the latest occupant of our islands and of northern europe was not the sea, but ice. the "palæocrystic sea," which we have been recently assured would account for our glacial phenomena, is of "the stuff that dreams are made of." there is not a jot or tittle of evidence for the former existence of such a sea over any part of britain or the continent of europe. [l] i no longer believe in this "great submergence." the marine shells in the high-level drift-deposits of our islands are "erratics," carried by the ice-sheet which occupied the basin of the irish sea. that the low-grounds were submerged but the amount of the submergence has not been ascertained; probably it did not exceed a few hundred feet. it is not necessary for my present purpose to enter further into the evidence of interglacial conditions. the latest northern ice-sheet was preceded by a long epoch of mild and genial conditions, during which elephants and hippopotami ranged north as far at least as yorkshire; while middle germany, as we know from the testimony of its interglacial deposits, enjoyed a similar delightful climate. and yet the immediately preceding glacial epoch had seen all those fertile regions covered with an ice-sheet that extended south as far as the fiftieth parallel of latitude. now the question with which i am at present concerned is the extent of the latest general glaciation. did the last great ice-sheet reach as far south as its predecessor? it certainly did not. its bottom-moraine has now been mapped out and distinguished from that of the older ice-sheet, and we know that it does not extend so far south as the latter. it is entirely absent over all the region to the west of the river elbe, from near dresden to hamburg and the coast of holland.[m] so that western germany and holland, which were covered by ice during the epoch of greatest glaciation, were not invaded by the ice-sheet underneath which the upper boulder-clay was accumulated. this latest ice-sheet, however, overwhelmed all mecklenburg and mark brandenburg, and streamed south nearly as far as saxony; its southern margin extended east through silesia, by liegnitz and breslau, into poland and russia. but the precise line it followed in the latter country has yet to be ascertained. we may surmise, however, that it nowhere reached so far south or east as the ice-flow of the earlier epoch. i may add that the southern termination of the latest ice-sheet is in many places marked out by heaps, mounds, and ridges of earthy sand, gravel, rolled stones, and erratics; in short, by terminal moraines. these, however, are frequently highly degraded and washed down. [m] klockmann, _jahrb. der k. preuss. geol. landesanstalt für _, p. . of the extension of glacier-ice in the british islands at the epoch in question i shall only say that the glaciation of scotland was hardly, if at all, less extensive than during the climax of the ice age. ireland, too, appears to have been almost as thickly mantled; but the ice-sheet that covered england and wales did not extend so far south as that of the penultimate glacial epoch, a considerable area in east anglia and the midland counties remaining apparently free from invasion. the scandinavian and british ice-sheets, however, again coalesced upon the floor of the north sea. iii. _the results of fluvio-glacial action in europe._ the third question which i now proceed to consider is the result produced by the rivers and torrents of the ice age. this, i am aware, is a wide subject, and one upon which much has been written. but there are a few points which may be advantageously discussed for the purpose of bringing into prominent view the conditions which obtained in the river-valleys of europe during the last great extension of glacier-ice. a little consideration will serve to convince one that the intense glacial conditions that obtained in our continent during the cold epochs of the glacial period were due to a low temperature, combined with excessive snow-fall. the winters, we can have no doubt, must have been prolonged and severe. but mere low temperature will not account for the enormous precipitation of snow. for this, great evaporation was required. and we are therefore forced to admit that the direct heat of the sun in summer must have been greater than it is in the same regions at the present day. now, if this were really the case (and i do not see how otherwise the facts can be explained), then we ought to meet with evidence of swollen rivers, torrents, and widespread inundations everywhere outside of the glaciated areas. and this is precisely what we do find. immense accumulations of coarse gravels are widely spread over all the valleys that head in regions which were formerly the sites of snow-fields and glaciers. these gravels are of such a character and are so distributed as to make it certain that they could not have been transported to and deposited in their present positions by rivers like those which now wind their way down the valleys of middle europe. still more remarkable are the enormous sheets of loam which are spread over much wider areas and reach to more considerable heights than the gravels. the origin of the gravels is sufficiently evident; they are simply the coarser detritus, swept along by the enormously flooded rivers of the glacial period, and meet with their analogues in the torrential gravels of modern glacier-valleys in the alps and other elevated regions. the more widely-spread loams, according to the opinion of most glacialists, represent the finer mud and silt deposited from the muddy waters of the same period. but the height to which such gravels and loams ascend is so great that those who hold them to be of fluvio-glacial origin have found it difficult to maintain this view. some writers, indeed, who have not sufficiently considered the weight of the evidence in its favour, have set it aside, and boldly suggested all kinds of wonderful hypotheses in its place. one imaginative author, for example, believes the wide-spread loams to be of volcanic origin, while another finds in the same deposits strong evidence of the deluge. by a well-known and experienced observer, the famous löss of middle europe is considered to be an Æolian accumulation--that is to say, a wind-blown deposit--the result of long-continued or frequently-repeated dust-storms. this is the opinion of baron richthofen, whose great work on china is so justly esteemed. he infers that at the time of the formation of our löss central europe was a dry desiccated region, just as wide areas in central asia are in our own day. he does not attempt to show us, however, how such climatic conditions could ever obtain in europe. in point of fact, the geographical conditions of our continent have not changed materially since pleistocene times, and the presence of the wide atlantic ocean, that laves all our western shores, is of itself sufficient to preclude the possibility of such a climate having obtained in middle europe. richthofen's theory likewise fails to account for the geographical distribution of the löss, and for many facts relating to its geology. only one of these last shall i mention. the löss is intimately associated with accumulations, the glacial and fluvio-glacial origin of which cannot be doubted. it belongs, in fact, to the glacial series, and was laid down at a time when vast snow-fields and ice-sheets existed, and when it is quite impossible that a dry climate could have characterised any part of our continent. in common with most geologists, i believe that the löss is simply an inundation-mud, deposited in temporary lakes and over flooded areas during the summer meltings of the snow- and ice-fields; and i shall now try to show how the occurrence at high levels of gravels and such loams as the löss may be accounted for without having recourse to volcanic action or to winds, or even to the deluge. i shall invoke no agencies other than those which we are perfectly well assured were in full operation during the ice age. now, i ask you, in the first place, to bear in mind that while a glacial epoch continued, extreme conditions could not have been restricted to the areas undergoing glaciation. there is abundant evidence, indeed, to show that heavy, snows occasionally covered other regions, and that in such places severe frosts acted upon the rocks and soils even of the low-grounds. need we wonder if at a time when the northern ice-sheet approached the fiftieth parallel of latitude in middle europe, when almost every mountain-group of central and southern europe had its snow-fields and glaciers--need we wonder if at such a time the climate of wide areas outside of the glaciated tracts was extremely ungenial? the more closely the superficial accumulations of such areas are studied, the more clearly do we perceive in them the evidence of cold and humid conditions. try, then, to picture to yourselves the probable aspect of those regions during a glacial epoch. immediately south of the northern ice-sheet deep snows must have buried large tracts of country, and such snows may have endured often for long years, notwithstanding the great melting that took place in summer. even much further south, as in spain and italy, deep snows would cover the lesser hills and hill-ranges, while frost would act energetically in many a district where such action is now either inconsiderable or unknown. such being the general conditions that must have obtained in the non-glaciated areas, let us very briefly consider what the results of such conditions must necessarily have been. every one has noticed, during the more or less rapid melting of snow in winter and early spring, that our streams and rivers are then much muddier than when in summer and autumn they are swollen by heavy rains. this of course is due to the action of frost, by means of which rocks are disintegrated and soils are broken up and pulverised, so that when thaw supervenes, the superficial covering becomes soaked with moisture like a sponge. to such an extent does this take place, that one may often see the saturated soil creeping, slipping, and even flowing down the slopes. the effect of mere thaw is of course much intensified when the water derived from melting snows is present. rills and tiny brooks then become converted into dark muddy torrents, and enormous quantities of fine-grained detritus are eventually swept into the rivers. the rivers rise in flood and inundate their plains, over the surface of which considerable deposits of loam and silt often accumulate. we cannot doubt that similar but much more intense action must have taken place over very wide regions in europe during a glacial epoch. such having necessarily been the case, we are not required to suppose that the löss and similar loams have been deposited entirely by rivers flowing from glaciers. it is doubtless true that most of the rivers headed in those days in glacier regions, and must in consequence have been highly discoloured with glacial mud, and probably a very large proportion of the loams in question consists of the fine flour of rocks--the result of glacial grinding. but the action of frost and thaw and melting snow upon the low-grounds, such as i have described, cannot be ignored, and seems to have played a more important _rôle_ than has yet been recognised. i think it helps us better to explain the well-known fact that land-shells are more or less commonly distributed through the löss. one can readily understand, at all events, how snail-shells might be swept down the slopes of the land at the time of the spring thaws, and how large numbers might find their way eventually into the swollen glacial rivers. i have often observed, during the melting of snow and the thawing of soils, quantities of snail-shells in the very act of being swept into our brooks and rills. and we are all familiar with the fact that, after a spring-flood has subsided, snail-shells, along with vegetable débris, are often plentifully stranded upon the valley-slopes and flood-plains of our rivers. admitting, then, that the löss and similar accumulations are simply inundation-loams formed at a time when glaciers were discharging immense volumes of muddy water, and when the low-grounds were liable every summer to the denuding action of melting snows, and so forth, i have yet to account for the fact that these supposed inundation-loams sometimes occur at a height of feet, or even of feet, above the present levels of the rivers. two theories have been advanced in explanation, each of which seems to me to contain an element of truth. it has, in the first place, been maintained, as by prestwich, that the löss at the higher levels was probably deposited long before the rivers had excavated their channels to their present depths. thus, during flood, they would be enabled to overflow tracts which they could not possibly have reached when they had deepened their valleys to a much greater degree. but while we must fully admit that the erosion effected by the rivers of the pleistocene or glacial period was excessive, yet we find it difficult or impossible to believe that great valleys, several miles in width, and two or three hundred feet in depth, were excavated in hard devonian and other equally durable rocks by the swollen and active rivers of the ice age. and although it is extremely probable that the löss at the highest levels is older than the similar deposit at the lowest levels of such a valley as the rhine, yet this does not get us out of our difficulty. the other view to which i have alluded takes little or no account of river-erosion, but maintains that the floods of the ice age were sufficiently great to reach the highest levels at which river-gravels and loams occur. it is likely enough that, under present conditions, we can form but a very inadequate idea of the vast bodies of freshwater which formerly swept down our valleys, but we may be pardoned if we express our inability to conceive of our european rivers flowing with a breadth of many miles, and a depth of two or three hundred feet. a few years before his death, mr. darwin made a suggestion to me, which i think gives us the true solution of the problem. he thought that during an ice age great beds of frozen snow might have accumulated over the low-grounds outside of the glaciated areas (in the manner i have already described), and that many valleys might have been filled to a considerable depth during a large part of the year with blown snow, afterwards congealed. in autumn, when the running water failed, the lines of drainage might in many cases be more or less choked, and it would be a mere chance whether the drainage, together with gravel, sand, and mud, would follow precisely the same lines during the next summer. such action being repeated year after year, it might well happen that many river-valleys might become largely filled with rudely alternating layers of frozen snow and fluviatile detritus. and if this were so, the flooded rivers in summer would be enabled to overflow much wider and more elevated tracts than they could otherwise have reached. as the climate became less excessive, we can conceive of the frozen snows gradually melting, and of river-detritus being deposited at lower and lower levels in the valleys. the probability of such frozen masses having choked up valleys and impeded the drainage during the ice age is not a mere plausible conjecture. in the far north of alaska--in a region which was certainly not overflowed by the north american ice-cap--extensive sheets of ice occur, more or less deeply buried under thick soil. nor can there be much doubt that these ice-masses date back to the glacial period itself, seeing that in the soils which overlie them we meet with remains of the mammoth and other contemporaneous mammalian forms. here, then, we have direct proof of the fact of frozen snow and ice having accumulated in the hollows of the land outside of the glaciated areas.[n] [n] i have given mr. darwin's views, and discussed the origin of the pleistocene fluvio-glacial deposits at some length in _prehistoric europe_, chaps, viii. and ix. to this work i refer for detailed geological evidence in support of the view advocated above. now, if such conditions existed in the valleys of middle europe, the widespread loss of those regions is readily accounted for. the occurrence of irregular sheets and shreds of gravel and loam at heights of more than a hundred feet above a valley-bottom offers no difficulty--it is in fact precisely the kind of phenomenon we might have expected. we are therefore not required to go out of our way to dream about impossible volcanic action, or to call upon the winds of heaven to help us, or upon the waters of the deluge to float us out of our difficulties. but while i believe the views i have now advocated sufficiently account for the appearances presented by the ancient valley-gravels and loams of central europe, there are two very considerable areas of löss which require some further explanation. the first of these is that broad belt of löss which extends from west to east across the plains of northern germany, and the northern boundary of which coincides with the limits reached by the last great ice-sheet, from which it spreads south to the foot-hills of the harz, and other mountains of middle europe. here we have a sheet of löss which bears no apparent relation to the valley-systems of the region in which it occurs. but the fact of its northern boundary being coincident with the terminal front of the last great northern ice-sheet at once suggests its origin. it is evident that this ice-sheet must have blocked the rivers flowing north, and dammed back their waters.[o] a wide sheet of muddy water must therefore have extended east and west over the very area which is now covered by the belt of löss in question. this temporary lake would doubtless be subject to great alternations of level--a portion draining away perhaps under the ice-sheet--but the water would for the most part make its way westward, and eventually escape into the english channel. from the waters of this great lake, fed by many large glacial rivers, abundant precipitation of loam and silt must have taken place. [o] the late mr. belt, as is well known, was of opinion that all the rivers flowing north in europe and asia were dammed back by a great polar glacier, and that all the low-tracts in the northern portions of the two continents were thus covered by wide inland seas of freshwater. as i do not believe that such a polar ice-cap existed during the glacial period, i cannot agree with mr. belt that the alluvial plains of northern siberia mark the sites of ice-dammed lakes. the second and by far the most extensive sheet of löss in europe is the so-called "black earth," or "tchernozem," with which such enormous tracts in southern russia are covered. this widespread löss--for such it really is--i have elsewhere tried to show consists of the flood-loam and inundation-muds laid down by the water escaping along the margin of the northern ice-sheet, which discharged its drainage in the direction of the black sea, its black colour being due to the grinding down and pulverising of the black jurassic shales which extend over such wide regions in middle russia. iv. _the extent of glaciation in north america._ the various phenomena of glaciation which go to prove that a great ice-sheet formerly covered a wide region in northern europe are developed on a still more extensive scale in north america. smoothed and striated rock-surfaces, crushed and dislocated rock-masses, and enormous accumulations of morainic débris and fluvio-glacial detritus, all combine to tell the same tale. the morainic accumulations of north america have been distributed upon the same principles as the similar deposits of our own continent. boulder-clay of precisely the same character as that of scotland and scandinavia, of switzerland and north italy, covers vast tracts in the low-grounds of the british possessions and the northern states of the union, where it forms enormous sheets, varying in thickness from or up to feet or more. in the rough laurentian high-lands, however, it is more sparingly developed, and the same is the case in the hilly regions of new england. in short, it thickens out upon the low-grounds, and thins off upon the steeper slopes, while it attains its greatest thickness and forms the most continuous sheets in the country that lies south of the great lakes. the southern limits of this deposit form a kind of rude semi-circle. from new york the boundary-line has been followed north-west through new jersey and pennsylvania to beyond the forty-second parallel, after which it turns to the south-west, passing down through ohio to cincinnati ( °); then, striking west and south-west through indiana, it traverses the southern portion of illinois. its course after it reaches the valley of the missouri has been only approximately determined, but it turns at last rather abruptly to the north-west, sweeping away in that direction through kansas, nebraska, dakota, and montana. the general course followed by the ice-sheet underneath which this boulder-clay was formed has been well ascertained, partly by the evidence of the clay and its contents, and partly by that of _roches moutonnées_ and striated rocks. the observations of geologists in canada and the states leave it in no doubt that an enormous sheet of ice flowed south over all the tracts which are now covered with boulder-clay. during a recent visit to canada and the states, i had opportunities of examining the glacial deposits at various points over a somewhat extensive area, and everywhere i found the exact counterparts of our own accumulations. in minnesota, wisconsin, iowa, illinois, indiana, and ohio, and again in new york, connecticut, and massachusetts, and the low-grounds of canada, i recognised boulder-clay of precisely the same character as that with which we are familiar at home. the glacial phenomena of the hudson valley and of the lower part of the connecticut river were especially interesting. in those regions the evidence of a southward flow of the ice is most conspicuous, and the phenomena, down to the smallest details, exactly recalled those of many parts of europe. professor dana, under whose guidance i visited the connecticut valley, showed me, at a considerable height upon the valley-slope, an ancient water-course, charged with gravel and shingle, which could not possibly have been laid down under present conditions. it was, in fact, a sub-glacial water-course, and resembled the similar water-courses which are associated with boulder-clay in our own country. if i met with only familiar glacial phenomena in the low-lying tracts traversed by me, i certainly saw nothing strange or abnormal in the hillier tracts. in passing over the dreary regions between the valley of the red river and lake superior i was constantly reminded of the bleak tracts of archæan gneiss in the north-west of scotland, and of the similar rough broken uplands in many parts of scandinavia and finland. the whole of that wild land is _moutonnée_. rough tors and crags are smoothed off, while boulder-clay nestles on the lee-side. in the hollows between the _roches moutonnées_ are straggling lakes and pools and bogs innumerable. frequently, too, one comes upon rounded cones and smooth banks of morainic gravel and sand, and heaps of coarse shingle and boulders, while erratics in thousands are scattered over the whole district. if you wish to have a fair notion of the geological aspect of the region i refer to, you will find samples of it in many parts of the outer hebrides and western ross-shire and sutherland. cover those latter districts with scraggy pines, and their resemblance to the uplands of canada will be complete. from descriptions given by travellers it would appear that morainic detritus--mounds and sheets of stony clay, gravel and sand, shingle, boulders, and erratics--are more or less plentifully sprinkled over all the british possessions and the islands of the arctic archipelago; so that we have every reason to believe that the ice-sheet which left its moraines at new york and cincinnati extended northwards to the arctic ocean. nor can there be much doubt that this same _mer de glace_ became confluent in the west with the great glaciers that streamed outwards from the rocky mountains; while we know for a certainty that the southern portion of alaska, together with british columbia and vancouver island, were buried in ice that flowed outwards into the pacific. along the eastern sea-board north of new york city there is no tract which has not been overflowed by ice. the islands in boston harbour are made up for the most part of tough boulder-clay; and boulder-clay and striated rocks occur also in maine, new brunswick, nova scotia, and newfoundland. thus we may say that the ice-covered region of north america was bounded on the north by the arctic, on the west by the pacific, and on the east by the atlantic oceans. the rocky mountains, however, divided the great _mer de glace_ that overflowed canada and the states from the ice that streamed outwards to the pacific. measured from the base of the rockies to the atlantic, the _mer de glace_ of canada and the states must have exceeded miles in width, and it stretched from north to south over degrees of latitude. outside of this vast region and the great mountain-ranges of the far west, there are few hilly areas in the states which reach any considerable elevation. south of the _mers de glace_ of the north and west, no such mountain-groups as those of middle and southern europe occur, and consequently we do not expect to meet with many traces of local glaciation. nevertheless, these have been recognised in the alleghany mountains, west virginia, and in the unaka mountains, between tennessee and north carolina. but the glaciers of those minor hill-ranges were of course mere pigmies in comparison with the enormous ice-streams that flowed down the valleys of the rocky mountains and the sierra nevada. even as far south as the sierra madre of mexico glaciers seem formerly to have existed; and mr. belt has described the occurrence of what he considered to be boulder-clays at a height of to feet in nicaragua. i have mentioned the fact that in europe we have, outside of the glaciated areas, certain accumulations (such as the gibraltar breccias) which could only have been formed under the influence of extreme cold. similar accumulations occur in north carolina, where they have been carefully studied by mr. w. c. kerr. according to mr. kerr, these deposits have crept down the declivities of the ground under the influence of successive freezings and thawings; and now that attention has been called to such phenomena, our american friends will doubtless detect similar appearances in many other places. the facts which i have now briefly indicated suffice to show that during the climax of glaciation north america must have presented very much the same appearance as europe. each continent had its great northern ice-sheet, south of which local glaciers existed in hilly districts, many of which are now far below the limits of perennial snow. we may note, also, that in each continent the _mers de glace_ attained their greatest development over those regions which at the present day have the largest rainfall. following the southern limits of glaciation in europe, we are led at first directly east, until we reach central russia, when the line we follow trends rapidly away to the north-east. the like is the case with north america. trace the southern boundary of the ice-sheet west of new york, and you find, when you reach the valley of the missouri, that it bends away to the north-west. now we can hardly doubt that one principal reason for the non-appearance of the _mer de glace_ in the far east of europe and the far west of america was simply a diminishing snow-fall. those non-glaciated regions which lay north of the latitudes reached by the ice-sheets were dry regions in glacial times for the same reasons that they are dry still. the only differences between glacial europe and america were differences due to geographical position and physical features. the glaciation of the urals was comparatively unimportant, because those mountains, being flanked on either side by vast land-areas, could have had only a limited snow-fall; while the mountain-ranges of western north america, on the other hand, being situated near the pacific, could not fail to be copiously supplied. for obvious reasons, also, the north american ice-sheet greatly exceeded that of europe. in all other respects the conditions were similar in both continents. v. _changes of climate in north america during the ice age._ american geologists are now pretty well agreed that their "interglacial deposits"--the existence of which is not disputed--have precisely the same meaning as the similar deposits which occur in europe. they tell of great climatic changes. at present, however, there is no certain evidence in the american deposits of more than one interglacial epoch; but the proofs of such an epoch having obtained are overwhelming. the occurrence again and again of fossiliferous beds intercalated between two separate and distinct sheets of boulder-clay and morainic accumulations, leaves us in no doubt that we are dealing with precisely the same phenomena which confront us in europe. no mere partial recession and re-advance of the _mer de glace_ will account for the facts. we have seen that during the culmination of the glacial period the american ice-sheet overflowed ohio, indiana, and illinois. now interglacial deposits occur as far north as the canadian shores of lakes ontario and superior, so that all the country to the south must have been uncovered by ice before those interglacial deposits were laid down. but the evidence entitles us to say much more than this. the interglacial beds of ohio, indiana, illinois, and other states, afford abundant evidence of a great forest-growth having covered the regions vacated by the ice of the penultimate glacial epoch. the trees of this forest-land included sycamore, beech, hickory, red-cedar, and others; and amongst the plants were grape vines of enormous growth, which, according to professor cox, "indicate perhaps the luxuriance of a warmer climate." at all events, the climate that nourished such a forest-growth could not have been less genial than the present. and such being the case, we may reasonably infer that the vast regions to the north of the lakes were no more inhospitable then than they are now. to this genial interglacial epoch succeeded the last glacial epoch, when a great ice-sheet once more enveloped a wide area. in the extreme east this latest _mer de glace_ appears to have reached as far south as that of the earlier epoch; but as we follow its terminal moraines westward they lead us further and further away from the southern limits attained by the preceding ice-sheet. these great terminal moraines form an interesting study, and the general results obtained by american observers have been very carefully put together by professor chamberlin. i traversed wide regions of those moraines in indiana, illinois, wisconsin, and minnesota, and, so far as my observations went, i could only confirm the conclusions arrived at by professor chamberlin and others. the mounds, banks, cones, and ridges are unquestionably moraines--of enormous dimensions, no doubt, but in all their phenomena strictly analogous to similar gravelly moraines in our own country and the continent. many of the american moraines consist almost entirely of water-worn material--sand, gravel, shingle, and boulders, together with large angular and sub-angular erratics. these deposits are generally stratified, and frequently show diagonal or false-bedding. in this and other respects they exactly reproduce--but of course on a much larger scale--our scottish kames, and the similar accumulations of north germany and finland, and the low-grounds of italy opposite the mouths of the great alpine lakes. the kames of wisconsin again and again reminded me of the gravelly moraines that cover the ground for many miles round the lower end of lake garda. it is this gravelly and sandy aspect of the american moraines that is most conspicuous, water-assorted materials seeming everywhere to form their upper and outer portions. now and again, however, a deep cutting discloses underneath and behind such water-worn detritus a mass of confused materials, consisting of clay, sand, gravel, shingle, and boulders, which are angular and sub-angular, often smoothed and striated, and of all shapes and sizes. according to mr. chamberlin, this unstratified material "is indistinguishable from true till, and is doubtless to be regarded as till pushed up into corrugations by the mechanical action of the ice." this grand series of moraines stretches from the peninsula of cape cod across the northern states, and passes in a north-westerly direction into the british possessions, over which it has been followed for some miles. the disposition of the moraines, forming as they do a series of great loops, shows that the ice-sheet terminated in a number of lobes or gigantic tongue-like processes. nothing seen by me suggested any marine action; on the contrary, every appearance, as i have said, betokened the morainic origin of the mounds; and mr. chamberlin assured me that their peculiar distribution was everywhere suggestive of this origin. no one who has traversed the regions i refer to is at all likely to agree with sir w. dawson's view, that the american mounds, etc., are the shore-accumulations of an ice-laden sea. the morainic origin of these accumulations having been demonstrated by american geologists, we are now able to draw another parallel between the european and american glacial deposits. we have seen that in europe the ice-sheet of the latest glacial epoch was by no means so extensive as that of the preceding glacial epoch. the same was the case in north america. moreover, in america, just as in europe, the latest occupant of the land was not the sea, but glacier-ice. in scotland and scandinavia the gradual disappearance of the latest ice-sheets was marked by a partial submergence, which in the former country did not greatly exceed feet, and in the latter feet. in america, in like manner, we find traces of a similar partial submergence. in connecticut this did not exceed or feet, but increased to some feet in the st. lawrence, and to over feet in the arctic regions. if there ever was during the glacial period a greater submergence than this in north america it must have taken place in earlier glacial or interglacial times, but of such a submergence no trace has yet been recognised. in this respect the american record differs somewhat from our own, for in britain we have evidence of a submergence of over feet, which supervened in times immediately preceding the latest great extension of continental ice.[p] but nowhere in middle europe, and nowhere in north america, in the region south and west of the great lakes, is there any trace of a general marine submergence. the "palæocrystic sea" is as idle a dream for the northern states of america as it is for any part of europe. [p] see footnote, p. . vi. _the results of fluvio-glacial action in north america._ the close analogies which obtain between the glacial and interglacial deposits of europe and north america are equally characteristic of the fluvio-glacial accumulations of the two continents. as in europe, so in america we meet with considerable sheets of gravel and shingle, sand, fine clay, and loam, which are evidently of freshwater origin. in the gently-undulating tracts of the northern states those deposits often spread continuously over wide regions; in the hillier districts, however, they are most characteristic of the valleys. they are very well represented, for example, in the connecticut valley, where they have been carefully studied by professor dana. like the similar deposits of our own continent, they have been laid down by the torrents and swollen rivers of the glacial period. the great range of moraines which marks the extreme limits reached by the latest ice-sheet is generally associated with sheets of gravel and sand, which one can see at a glance are of contemporaneous origin, having been spread out by the water escaping from the melting ice. nor can one doubt that the vast sheets of löss in the missouri and mississippi valleys are strictly analogous in origin, as they are in structure and disposition, to the löss of europe. i have spoken of the probable existence of a glacial lake formed by the damming back of the rhine and other rivers by the european ice-sheet. now, in north america we meet with evidence of the same phenomenon. when the last ice-sheet of that continent attained its maximum development, all the water escaping from its margin in the north states necessarily flowed south into the mississippi and missouri rivers. but in course of time the ice melted away beyond the drainage-area of those rivers, and disappeared from the valley of the red river of the north, which, it will be remembered, empties itself northward into lake winnipeg. when the ice-front had retired so far it naturally impeded the drainage of the red river basin, and thus formed a vast glacial lake, the limits of which have been approximately mapped out by mr. upham, by whom the ancient lake has been designated lake agassiz. the deposits laid down in this lake consist of finely laminated clays, etc., which resemble in every particular the similar unfossiliferous clays so frequently found associated with glacial accumulations in europe. had the drainage of the red river valley been south instead of north, the clays and loams of the far north-west would not have been arrested and spread out where they now are, and manitoba would have been covered for the most part with loose shingle, gravel, and sand. thus the final disappearance of the american ice-sheet was marked by the formation not only of moraines, but of flood-gravels and torrential- and inundation-deposits of the same character as those with which we are familiar at home. wherever similar geographical conditions prevailed, there similar geological results followed. vii. _conclusion._ there are many other points of resemblance between the glacial and fluvio-glacial accumulations of the two continents, but to these time forbids any reference. indeed, i cannot recall any signal difference. such differences as do occur are due simply to the varying conditions of the two continental areas. the glacial phenomena of north america are a repetition of those of europe, but upon a much grander scale. the boulder-clays of the former continent, in their composition, structure, and distribution, exactly recall our own. interglacial beds occur under similar circumstances in both continents; and the same is the case with the gravelly moraines and fluvio-glacial accumulations. we are driven, then, to the conclusion that the physical conditions of the glacial period were practically the same in europe and north america. what those conditions were i have already indicated, and have shown that the results arrived at by geologists are not vague dreams and speculations, but a logical induction from well-ascertained facts. before we can believe that volcanic eruptions, a general deluge, or a palæocrystic sea have produced the many varied phenomena of our glacial formations, either in whole or in part, we must first shut our eyes and then erase from our minds all knowledge of the facts which have been so laboriously gathered by a long succession of competent observers. [illustration: plate iii distribution of ice past and present. polar view of the world on lamberts equal area projection ] vii. the intercrossing of erratics in glacial deposits.[q] [q] _the scottish naturalist_, . among the many phenomena connected with the glacial deposits of this country which have puzzled geologists there is none more remarkable than the "intercrossing of erratics." the fact that such wandered blocks have apparently crossed each other's tracks in their journeys appears at first sight inexplicable on the assumption that their transport has been effected by land-ice. the phenomena in question, therefore, have always been appealed to by those who uphold the iceberg origin of our boulder-clays, etc., as evidence decisively in favour of their views. no one can deny that any degree and amount of intercrossing might take place in the case of icebergs. we can readily conceive how floating ice, detached from a long line of coast, might be compelled by shifting winds and changing currents to tack about again and again, so as to pursue the most devious course, and scatter their stony burdens in the most erratic manner over the sea-bottom; while, on the other hand, it is quite impossible to understand how a similar irregular distribution of erratics could take place under one and the same glacier flowing in a determinate direction. it is little wonder, then, that the curious phenomena of the intercrossing of erratics should have had much importance attached to it by the upholders of the iceberg theory, seeing that all the other proofs which have been adduced in favour of this theory have only served to demonstrate its insufficiency. upon the facts connected with the intercrossing of erratics, the supporters of this time-honoured theory are now making what i must believe is their last stand. i purpose therefore, in this paper, to give a short outline of those facts, with the view of showing that so far from being antagonistic to the land-ice theory, they are in complete harmony with it; and indeed must be considered as affording an additional demonstration of its truth. some years ago i called attention to the fact that in the middle districts of scotland the boulder-clay not infrequently contains a curious commingling of northern and southern erratics.[r] i showed that this was the case throughout a belt of country extending from the sea-coast near ayr, north-east to the valley of the irvine, and thence across the watershed into the avon, and east to lesmahagow, then down the valley of the clyde to carluke, stretching away to the east by wilsontown, and thereafter continuing along the crest of the pentlands and the northern slopes of the lammermuir hills, by reston and ayton, to the sea. "all along this line," i remarked, "we have a 'debatable ground' of variable breadth, throughout which we find a commingling in the till of stones which have come from north and from south. south of it, characteristic highland stones do not occur, and north of it stones derived from the south are similarly absent." the explanation of these facts is obvious. the belt of ground referred to was evidently the meeting-place of the highland and southern _mers de glace_. here the two opposing ice-flows coalesced and became deflected by their mutual pressure to right and left--one great current going east and another west. it is evident that the line of junction between the two _mers de glace_ could not be rigorously maintained in one and the same position during a period of glaciation, but would tend to oscillate backwards and forwards, according as one or the other ice-sheet prevailed. sometimes the southern ice-sheet would be enabled to push back the northern _mer de glace_, while at other times the converse would take place. nor is it necessary to suppose that the advance of one ice-sheet was general along the whole line. on the contrary, it is most likely that the movement was quite irregular--an ice-sheet advancing in some places, while at other points its line of junction with the opposing ice-sheet remained stationary, or even retrograded. such movements would obviously give rise to oscillations in the sub-glacial débris of clay and stones; and thus we have a simple and natural explanation of those intercrossings of erratics which are so characteristic of that region which i have termed the "debatable ground." and this conclusion is borne out by the fact that the glacial striæ of the same "debatable ground" afford like evidence of oscillation in the trend of the ice-flow. [r] _great ice age_, nd edit., p. . along the base of the highland mountains in forfarshire, etc., we meet with similar intercrossings of erratics. thus we occasionally encounter in the boulder-clays overlying the silurian regions erratics of old red sandstone rocks which have come from the east or south-east; while the abundant presence of erratics of silurian origin, on the other hand, bespeak an ice-flow from the west towards the low-grounds. in some places within the silurian area we encounter a greyish-blue boulder-clay containing silurian fragments only, while in other places within the same area the boulder-clay becomes reddish, and is charged with many boulders of old red sandstone rocks. now the greyish-blue till could only have been laid down by glacier-ice descending from the silurian high-grounds to strathmore, while the red boulder-clay points to a partial invasion of the silurian regions by land-ice, which had previously traversed the lower-lying old red sandstone areas. these apparently contradictory movements are readily accounted for by the former presence in the area of the north sea of the great scandinavian _mer de glace_. dr. james croll was the first to point out that the glacial phenomena of caithness and the shetlands could only be accounted for by the advance of the scandinavian ice-sheet towards our coasts, where it encountered and deflected the scottish ice-sheet out of its normal course--a sagacious induction, which the admirable and exhaustive researches of my colleagues, messrs. b. n. peach and j. horne, have now firmly established. the lower blue boulder-clay was evidently accumulated at a time when the scottish ice was able to flow more or less directly east or south-east towards what is now the coast-line; while the overlying red boulder-clay points to a subsequent period when the presence of the scandinavian _mer de glace_ was sufficiently great to compel the scottish ice out of its normal course, and cause it to flow in a north-easterly direction. in doing so it now and again passed from tracts of old red sandstone to invade the silurian area, and thus an overlying red boulder-clay was here and there accumulated upon the surface of a greyish-blue till in which not a single fragment of any old red sandstone rock occurs. recently messrs. b. n. peach and j. horne, in a most instructive paper on the "glaciation of caithness,"[s] have described some remarkable comminglings of material which occur in a region where the glacial striæ afford equally striking evidence of conflicting ice-movements. these phenomena are developed here and there along a line which indicates the meeting-place of two rival ice-streams, on each side of which the boulder-clay presents different characteristics--the one boulder-clay being the _moraine profonde_ of the ice that flowed ene. and nne. towards the caithness plain, while the other is an accumulation formed underneath the ice that streamed across that plain from se. to nw. these phenomena are thus, as my colleagues remark, quite analogous to those met with in the middle districts of scotland, as described by me, and referred to in a preceding paragraph. now it is obvious that while these examples of "intercrossings" of erratics and "cross-hatching" of striæ all go strongly to support the land-ice theory of the glacial phenomena, they at the same time negative the notion of floating-ice having had anything to do with the production of the phenomena under review. [s] _proceedings royal physical society_, edinburgh, . before considering the evidence adduced by mr. mackintosh and others as to the intercrossings of erratics in the drift-deposits of england, i shall mention some of the more remarkable examples of the same phenomena which have been noticed by continental geologists. the first cases i shall cite are those which have been observed in the glacial accumulations of the rhone valley in eastern france. the land-ice origin of these accumulations has never been called in question, and as the intercrossings of erratics in that region are not only more common, but much more striking and apparently inexplicable than any which have been noticed elsewhere, it will be admitted that they of themselves afford a strong presumption that the conflicting courses followed by the erratics in certain regions of our own country are the result rather of oscillations in the flow of land-ice than of the random and eccentric action of icebergs. the researches of swiss and french glacialists have proved that during the climax of the glacial period an enormous area in the low-grounds of eastern france was covered with a huge _mer de glace_, formed by the union of the great rhone glacier with the glaciers descending from the mountains of savoy and dauphiny. a line drawn from bourg by way of chatillon, villeneuve, trévoux, and lyons to vienne, and thence south-east by beaurepaire to the valley of the isère, a few miles above st. marcellin, indicates roughly the furthest limits reached by the _mer de glace_. over all the low-grounds between that terminal line and the mountains are found widespread sheets of boulder-clay and sand and gravel, together with loose erratics. now and again, too, well-marked terminal moraines make their appearance, while the rock-surfaces, when these are visible and capable of bearing and retaining glacial markings, present the usual aspect of _roches moutonnées_. the same kinds of morainic materials and ice-markings may of course be followed up into the valleys not only of the alps properly so-called, but also into those of the hills of bugey and the secondary mountain-chain of savoy and dauphiny. it has indeed long been known that local glaciers formerly occupied the mountain-valleys of bugey. for example, a number of small glaciers have descended from the slopes of the mountains west of belley (such as bois de la morgue, bois de lind, etc.) to the rhone, and again from mont du chat to the north-west. these glaciers were quite independent of the greater ice-streams of the neighbouring alps of savoy, and the same was the case with the glaciers of that mountainous tract which extends from nantua south to culoz, between the valleys of the ain and the rhone. from this elevated region many local glaciers descended, such as that of the valromey, which flowed for a distance of some twenty miles from north to south. again, similar local glaciers have left abundant traces of their former presence throughout the mountainous belt of land that stretches between chambery and grenoble to the west of the valley of the isère. the moraines of all those local glaciers, charged as they are with the débris of the neighbouring heights, clearly indicate that the local glaciers flowed each down its own particular valley. there are certain other appearances, however, which seem at first sight to contradict this view. sometimes, for example, we encounter in the same valleys erratics which do not belong to the drainage-system within which they occur, but have without doubt been derived from the higher alps of switzerland and savoy. and the course followed by these foreign erratics has crossed at all angles that which the local glaciers have certainly pursued--occasionally, indeed, the one set of erratics has travelled in a direction exactly opposed to the trend taken by the others. as examples, i may cite the case of the erratics which occur in petit bugey. in this district we encounter many locally-derived erratics which have come from mont du chat to the west of the lac du bourget--that is to say, they have travelled in a north-westerly direction. but in the same neighbourhood are found many erratics of alpine origin which have been carried from north-east to south-west, or at right angles to the course followed by the local erratics. again, in the valley of the seran we have evidence in erratics and terminal moraines of a local glacier which flowed south as far as the lyons and geneva railway, in the neighbourhood of which, a few miles to the west of culoz, its terminal moraines may be observed. this is the extinct glacier du valromey of mm. falsan and chantre. now it is especially worthy of note that in the same valley we have distinct evidence of an ice-flow from south to north--_i.e._, _up_ the valley. erratics and morainic materials which are unquestionably of alpine origin have been followed a long way up the seran valley--for two-thirds of its length at least. before they could have entered that valley and approached the slopes of romey, they must have travelled down the valley of the rhone from the higher alps of savoy in a _south-west_ and _south_ direction until they rounded the montagne du grand colombier. it was only after they had rounded this massive mountain-ridge that they could pursue their course up the valley of the seran, in a direction precisely opposite to that which they had previously followed. these and many similar and even more remarkable examples of the "intercrossings" of streams of erratics are described by mm. falsan and chantre, and graphically portrayed in their beautiful and instructive work on the "ancient glaciers and erratic deposits of the basin of the rhone"; and the explanation of the phenomena given by them is extremely simple and convincing. the local erratics and moraines pertain partly to the commencement and partly to the closing stage of the glacial period. long before the south branch of the great glacier of the rhone had united with the glacier of the arve, and this last with the glaciers of annecy and beaufurt, and before these had become confluent with the glacier of the isère, etc., the secondary mountain-ranges of savoy and dauphiny and the hills of bugey were covered with very considerable snow-fields, from which local glaciers descended all the valleys to the low-ground. but when the vast ice-flows of switzerland, upper savoy, etc., at last became confluent, they completely overflowed many of the hilly districts which had formerly supported independent snow-fields and glaciers, and deposited their bottom-moraines over the morainic débris of the local glaciers. in other cases, where the secondary hill-ranges were too lofty to be completely drowned in the great _mer de glace_, long tongues of ice dilated into the valleys, and compelled the local ice out of its course; sometimes, as in the case of the valromey, forcing it backward up the valleys down which it formerly flowed. but when once more the mighty _mer de glace_ was on the wane, then the local glaciers came again into existence, and reoccupied their old courses. and thus it is that in the hilly regions at the base of the higher alps, and even out upon the low-grounds and plains, we encounter that remarkable commingling of erratics which has been described above. not infrequently, indeed, we find one set of moraines superposed upon another, just as in the low-grounds of northern germany, etc., we may observe one boulder-clay overlying another, the erratics in which give evidence of transport in different directions. the observations recorded by mm. falsan and chantre, and their colleagues, thus demonstrate that "intercrossings" of erratics of the most pronounced character have been brought about solely by the action of glaciers. in the case of the erratics and morainic accumulations of the basin of the rhone, the action of icebergs is entirely precluded. i may now mention some of the more remarkable examples of intercrossings of erratics which have been recorded from the glacial accumulations of north germany, etc. an examination of the glacial striæ, _roches moutonnées_, and boulder-clays of saxony leads to the conviction, according to credner, penck, torell, helland, and others, that the whole of that region has been invaded by the great scandinavian _mer de glace_ which flowed into saxony from nne. to ssw. erratics from southern sweden and gothland occur in the boulder-clay, and the presence of these, taken in connection with the direction of the glaciation, leaves us no alternative but to agree with the conclusions arrived at by the saxon geologists. but, apparently in direct contradiction of this conclusion, we have evidence to show that boulders of the same kinds of rock occur in denmark and holland, pointing to a former ice-flow from north-east to south-west and west. thus boulders derived from gothland occur at gröningen in holland, while fragments from the island of Öland are met with in faxö; and erratics from the borders of the gulf of finland are encountered at hamburg. indeed, when geologists come to examine the erratics in north germany and poland generally, they find evidence of apparently two ice-flows--one of which went south-south-west, south, and south-east--spreading out, as it were, in a fan-shape towards the southern limits reached by the great "northern drift,"--while the other seems to have followed the course of the baltic depression, overflowing the low-grounds of northern prussia, holland, etc., in a south-west and west direction. now, it is quite evident that no one _mer de glace_ could have followed these various directions at one and the same time. the explanation of the apparent anomaly, however, is not far to seek. it is reasonable to infer that long before the _mer de glace_ had attained its maximum dimensions, when as yet it was confined to the basin of the baltic and was only able to overflow the northern regions of prussia, etc., its course would be determined by the contour of the pavement upon which it advanced. it would, therefore, be compelled to follow the baltic depression, and for a long time it would carry erratics from finland, the baltic islands, and eastern sweden in a south-west and west-south-west direction. and this would continue to be the direction even after a considerable portion of the low-grounds of prussia, etc., had been overflowed. but when the ice-sheet was enabled to advance south into saxony, poland, and lithuania, erratics from finland, the baltic islands, etc., would necessarily cease to travel towards the west, and hold on a south-south-east, south, and south-south-west course. again, when the _mer de glace_ was on the decline, a time would return when the ice, as before, would be controlled in its flow by the baltic depression, and this would give rise to a further distribution of erratics in a prevalent west-by-south direction.[t] [t] for a fuller discussion of the distribution of erratics on the continent, i may refer to appendix, note b, in _prehistoric europe_, where the reader will find references to the literature of this interesting subject. [continental geologists now recognise a distinct stage of the ice age, during which their "upper diluvium" was deposited by a great glacier that occupied the basin of the baltic. this "great baltic glacier" appears to have been contemporaneous with the local ice-sheets and valley-glaciers of the highlands and other mountain-tracts of our island. see article x. .] no one of late years has been more assiduous in the collection of facts relating to the intercrossing of erratics in the drift-deposits of england than mr. d. mackintosh.[u] he has written many instructive and interesting descriptions of the phenomena in question, which he justly thinks are of prime importance from a theoretical point of view. in a recent paper[v] he presents us with the results of a systematic survey of the direction and limits of dispersion of the erratics of the west of england and east of wales, which he evidently is of opinion afford strong support to the iceberg theory, while at the same time they are directly opposed to the theory of transport by land-ice. i have attentively considered all the arguments advanced by mr. mackintosh in favour of his views--the one upon which he apparently lays most stress being that of the intercrossings of erratics observed by him--and i shall now proceed to point out how the phenomena described by him are most satisfactorily explained by the land-ice theory. they seem to me, indeed, to lend additional support to that theory, in the same manner as the intercrossings of boulders observed in scotland, northern germany, etc., and sub-alpine regions of france. mr. mackintosh calls attention to the fact that erratics of the well-known criffel granite are found scattered over a large part of the plain of cumberland, from which they extend south along the coast to near the mouth of the estuary of the duddon. they reappear on the coast in the neighbourhood of blackpool and liverpool, and again at intervals on the coasts of north wales from flint to colwyn bay, and thence to penmaenmawr and the neighbourhood of beaumaris. they are dispersed over the peninsula of wirral and the cheshire plain, etc., and they have been followed south-east as far as the neighbourhood of cardington, near church stretton, burton, wolverhampton, stafford, hare castle, macclesfield, and manchester. this great stream of boulders, therefore, spreads out to south-east, south, and south-west: the erratics, to quote mr. mackintosh, "have radiated from an area much smaller than their terminal breadth." the same is the case, i may remark in passing, with erratics in the boulder-clays of scotland, scandinavia, north germany, etc., as also with those in the drift-deposits of the great rhone glacier and other ancient glaciers both on the north and south side of the alps. now, the course followed by the criffel erratics is crossed at an acute angle by the path pursued by many boulders of eskdale granite, and various felspathic rocks derived from the cumberland mountains. for example, cumberland erratics of the kinds mentioned occur near st. asaph and moel-y-tryfane and in anglesey, and they have been followed over a wide district in cheshire, etc., extending as far south as church stretton and wolverhampton, and as far east as rochdale. more than this, we find that numerous erratics of felstone, derived from the mountain of great arenig, in north wales, have gone to north-east as far as halkin mountain, in flintshire, eryrys, near llanarmon, and chirk, from which last-named place they have been traced in a south-easterly direction to birmingham, bromsgrove, etc. a glance at the map of england will show that this south-easterly drift of erratics crosses at an acute angle the paths followed by the criffel granite boulders and the erratics derived from cumberland, so that we have now several intercrossings to account for. how can this be done by the land-ice theory? [u] this enthusiastic geologist died in . [v] _quart. journ. geol. soc._, vol. xxxv. p. the explanation seems to me obvious, for the phenomena are, after all, less striking than similar appearances which have been observed in scotland, especially by my colleagues, messrs. peach and horne, in caithness and the orkney and shetland islands; and they are certainly less intricate than the facts recorded by mm. falsan and chantre concerning the intercrossing, interosculation, and direct opposition of erratic paths in savoy and dauphiny. we have only to reflect that the great _mer de glace_--to which, as i believe, all the english phenomena are due--did not come into existence and attain its maximum dimensions in the twinkling of an eye, nor could it afterwards have disappeared in the same sudden manner. on the contrary, a period of local glaciation must have preceded the appearance of the great ice-sheet. at first, and for a long time, permanent snow would be confined to the higher elevations of the land, and glaciers would be limited to mountain-valleys; but as the temperature fell the snow-line would gradually descend, until at last, probably after a prolonged period, it reached what is now the sea-level. thus the formation of _névé_ and glacier-ice would eventually take place over what are now our low-grounds, and other tracts also, which are now submerged. it is quite impossible that the vast sheets of ice which can be demonstrated to have covered scotland, a large part of england, ireland, scandinavia, and north germany, and even the limited area of the faröe islands, could possibly have been fed by the snow-fields of mountain-heights only. the precipitation and accumulation of snow, and the formation of _névé_ and glacier-ice, must have taken place over enormous regions in what are now the temperate latitudes of europe. it is obvious that the direction of ice-flow in the basin of the irish sea opposite the south of scotland and the west of england, while preserving a general southerly trend, would vary at different periods. before the _mer de glace_ in that basin had attained its climax there must have been a time when the ice, streaming outwards from the high-grounds of cumberland, was enabled to push its way far westward out into the basin of the irish sea. at that time it was still able to hold its own against the pressure exerted by the scottish ice. but as the general _mer de glace_ increased in thickness, the course of the cumberland ice would be diverted ever further and further to the south-east, until, eventually, the scottish ice came to hug the coast of cumberland, and to overflow lancashire in its progress towards the south-east. so gorged with ice did the basin of the irish sea become, that a portion of the scottish ice was forced over the plain of cumberland and up the valley of the eden, where it coalesced with the ice coming north from the shap district, and thereafter flowed in an easterly direction to join the great _mer de glace_ of the north sea basin. thus the intercrossings of the criffel and cumberland erratics described by mr. mackintosh receive a ready explanation by the land-ice theory. nor do the intercrossings of the welsh erratics with those derived from scotland and cumberland offer any difficulty. the ice coming from the welsh mountains would naturally be deflected towards south-east by the _mer de glace_ that streamed in that direction, and might quite well have carried its characteristic boulders as far as birmingham before the general _mer de glace_ had attained its greatest dimensions. but when that period of maximum glaciation arrived, the welsh boulders would be unable to travel so far towards the east, and the scottish and cumberland boulders would then cross the path formerly followed by the felstone erratics from great arenig. again, it is evident that when the _mer de glace_ was gradually decreasing similar oscillations of the ice-flow would take place, but in reverse order, and thus would give rise to a second series of intercrossings. moreover, we must remember that the glacial period was characterised by several great changes of climate. it was not one continuous and prolonged period of cold conditions, but consisted rather of a succession of arctic and genial climates; so that the same countries were overrun at different epochs by successive _mers de glace_, each of which would rework, denude, and redistribute to a large extent the morainic materials of its predecessor, and thus might well cause even greater complexity in the dispersion of erratics than has yet been recognised anywhere in these islands. mr. mackintosh refers to the occurrence of chalk-flints and lias fossils associated with northern erratics in the drift-deposits of the west of england, the presence of which, he thinks, is fatal to the theory of transport by land-ice. thus, he says, chalk-flints, etc., have been met with at lillieshall (east of wellington), at strethill (near ironbridge), at seisdon (between wolverhampton and bridgenorth), at wolverhampton, near stafford, and near bushbury. chalk-flints have also been found as far west as malvern and hatfield camp, south of ledbury. all these erratics have crossed england from the east, according to mr. mackintosh and other observers. not only so, but, as mr. mackintosh remarks, those found at wolverhampton, birmingham, etc., "must have _crossed the course_ of the northern boulders near its southerly termination." and since both northern and eastern erratics are found associated in the same drift-deposit, it seems to him "impossible to explain the intercrossing by land-ice or glaciers." now, on the contrary, those eastern erratics are scattered over the very districts where i should have expected to find them. the observations of geologists in east anglia have shown that that region has been invaded by the _mer de glace_ of the north sea basin.[w] this remarkable glacial invasion is proved not only by the direction followed by stones of local derivation, and by boulders which have come south from scotland and the northern counties, but by the occurrence in the boulder-clay at carnelian bay and holderness of erratics of certain well-known norwegian rocks, which have been recognised by mr. amund helland. the occurrence of chalk-flints and fragments of oolitic rocks in the neighbourhoods mentioned by mr. mackintosh thus only affords additional evidence in favour of the land-ice origin of the drift-deposits described by him. the _mer de glace_ that flowed down the east coast of england seems to have encroached more and more upon the land, until eventually it swept over the low-lying midlands in a south-westerly direction, and coalesced with the _mer de glace_ that streamed inland from the basin of the irish sea, and the ice that flowed outwards from the high-grounds of wales. the united ice-stream would thereafter continue on its south-westerly course down the severn valley to the bristol channel. i have no doubt that mr. mackintosh will yet chronicle the occurrence of chalk-flints and other eastern erratics from localities much further to the south than ledbury. [w] see mr. skertchly's description of east anglian deposits in _great ice age_, nd edit., p. . again, considerable stress has been laid by mr. mackintosh upon the occurrence of chalk-flints in the drift-deposits of blackpool, dawpool, parkgate, halkin mountain, wrexham, the peninsula of wirral, runcorn, delamere, crewe, leylands, piethorne (near rochdale), and other places. "all these flints," mr. mackintosh remarks, "belong to the basin of the irish sea, and have almost certainly crossed the general course of the northern boulders on their way from ireland." here, unfortunately, the irish sea intervenes to conceal the evidence that is needed to enable us to track the exact path followed by the erratics in question. i am not so certain as mr. mackintosh that the chalk-flints he refers to came from the north of ireland. chalk-flints occur pretty numerously in the drift-deposits in the maritime districts of north-eastern scotland, which we have every reason to believe have been derived from an area of cretaceous rocks covering the bottom of the adjacent sea; and for aught one can say to the contrary, patches of chalk-with-flints may occur in like manner in the bed of the irish sea. i cannot at present remember whether any boulders of the basalt-rocks, which are associated with the chalk in the north of ireland, have been recognised in the drifts of the west of england; but if the chalk-flints really came from antrim, it is more than probable that they would be accompanied by fragments of the hard igneous rocks which overlie the cretaceous strata of north ireland. chalk and chalk-flints occur in the boulder-clay of the isle of man, where they are associated, mr. horne tells us, with criffel granite and fragments of a dark trap-rock.[x] possibly these last are basalt-rocks from antrim. it seems reasonable, therefore, to believe that erratics of irish origin have found their way to the isle of man; and if this be so, it may be permissible to assume that the chalk-flints of blackpool, etc. (and perhaps also some of the basalt-rocks), have come from the same quarter. mr. horne has no doubt that the irish erratics were brought to the isle of man by land-ice. referring to the conclusion arrived at by mr. close that the irish _mer de glace_ "was probably not less than feet in depth," he remarks: "it is highly probable that this great mass of irish ice succeeded, after a hard battle (_i.e._, with the scottish ice-sheet), in reaching the manx coast-line. it is not to be supposed that the normal momentum of the respective ice-sheets remained constant. the moving force must have varied with changing conditions. on the other hand, it is quite possible that there may have been an 'under-tow' of the ice from the north-east coast of ireland, which would easily account for antrim chalk and chalk-flints in the manx till." i would go further, and state my conviction that before the united ice-sheets had attained their maximum development, it is almost certain that the ice flowing into the irish sea basin by the north channel would for a long time exceed in mass the coalescent glaciers that descended from the southern uplands of scotland, and would therefore be enabled to extend much further to the east than it could at a later date, when the general _mer de glace_ had reached its climax. it might thus have advanced as far as and even beyond the isle of man. this inference is based upon the simple fact that the area drained by the _mer de glace_ of the north channel was very much greater than the area extending from the watershed of the southern uplands of scotland to the isle of man. erratics from the north of ireland would thus travel down the bed of the north channel, and eventually be distributed over a wide area up to and possibly even some distance beyond the isle of man. but as the scottish and cumbrian ice-flows gradually increased in importance, the _mer de glace_ coming from the north channel would be forced further and further to the west, until the ice-flow issuing from the high-grounds of kirkcudbright at last succeeded in reaching the middle of the irish sea basin. this gradual modification of the general ice-flow in that basin would of course give rise to a redistribution of the ground-moraine, and the irish erratics would then travel onwards underneath the scottish ice, and eventually reach the low-grounds of lancashire and cheshire, along with erratics from criffel and the cumbrian mountains. it is, therefore, quite unnecessary to suppose that the _mer de glace_ of the north channel actually crossed the whole breadth of the basin of the irish sea to invade lancashire, cheshire, and north wales. had this been the case, chalk-flints, chalk, and many other kinds of rock derived from the north of ireland, and even from arran and argyll, would have abounded in the drifts of the west of england. erratics coming from ireland could not possibly have travelled underneath irish ice further east than the isle of man. there or thereabouts, as i have said, the _mer de glace_ of the north channel would begin to encounter the ice streaming down from the uplands of galloway and the mountains of cumberland: and as the ice from these quarters increased in thickness, it would gradually override what had formerly been the bottom-moraine or till of the north channel _mer de glace_. thus irish erratics would become commingled with erratics from criffel, etc., and be carried forward in a southerly and south-easterly direction. the chalk-flints in the drifts of lancashire, cheshire, etc., are probably therefore _remaniés_--the relics of the bottom-moraine of the north channel _mer de glace_ rearranged and redistributed. and this is why they and other irish rocks are so comparatively rare in the glacial accumulations of the west of england. [x] _trans. edin. geol. soc._, vol. ii., . thus all the instances of intercrossings adduced by mr. mackintosh as favouring the iceberg theory, and condemning its rival, i would cite as proving exactly the opposite. so far from presenting any real difficulty to an upholder of the land-ice theory, they, in point of fact, as i have already remarked, lend that view additional support. it is not my purpose to criticise all the arguments and reasons advanced by mr. mackintosh in favour of his special views, but i may be allowed a few remarks on the somewhat extraordinary character of the agents which, according to him, were mainly instrumental in producing the drift-phenomena of western england. before doing so, however, i may point out that, in ascribing the transport of erratics in that region (and, by implication, the formation of the boulder-clays, etc., with which most of these erratics are associated) to floating-ice and sea-currents, mr. mackintosh has failed to furnish us with any "fossil evidence" to show that western england was under water at the time the boulder-clays and erratics were being accumulated. he speaks of cold and warm currents, but where do we find any traces of the marine organisms which must have abounded in those waters? where are the raised sea-beaches which must have marked the retreat of the sea? where do we encounter any organic relics that might help us to map out the zones of shallow and deep water? the sea-shells, etc., which occur in the boulder-clays are undeniably _remaniés_; they are erratics just as much as the rock-fragments with which they are associated. similar assemblages of organic remains are met with in the till of caithness, where shallow-water and deep-sea shells, and shells indicative of genial and again of cold conditions, are all confusedly distributed throughout one and the same deposit. the same or analogous facts are encountered in the _blocklehm_ of some parts of prussia, marine and freshwater shells occurring commingled in the boulder-clay. nay, even in the _moraine profonde_ of the ancient rhone glacier, broken and well-preserved shells of miocene and pliocene species appear enclosed in the tumultuous accumulation of clay, sand, and erratics. and precisely similar phenomena confront us in the glacial deposits of the neighbourhood of lago lugano. mr. mackintosh refers to the so-called "stratification" of the boulder-clay, as if that were a proof of accumulation in water. but a rude kind of bedding, generally marked by differences of colour, and sometimes by lines of stones, was the inevitable result of the sub-glacial formation of the boulder-clay. the "lines of bedding" are due to the shearing of the clay under great pressure, and may be studied in the boulder-clay of switzerland and italy, and in the till not only of the lowlands but of the highlands of scotland. occasionally the "lines" are so close that the clay sometimes presents the appearance of rude and often wavy and irregular lamination--a section of such a boulder-clay reminding one sometimes of that of a gnarled gneiss or crumpled schist. and these appearances may be noted in boulder-clays which occupy positions that preclude the possibility of their being marine--as in certain valleys of the highlands, such as strathbraan, and in the neighbourhood of como, in italy. this "lamination" is merely indicative of the intense pressure to which the till was subjected during its gradual accumulation under the ice. it is assuredly not the result of aqueous action. aqueous lamination is due to sifting and winnowing--the coarser or heavier and finer or lighter particles being separated in obedience to their different specific gravity, and arranged in layers of more or less regularity according to circumstances. there is nothing of this kind of arrangement, however, in the so-called stratified boulder-clay. if the clay of an individual lamina be washed and carefully sifted, it will be found to be composed of grains of all shapes, sizes, and weights, down to the finest and most impalpable flour. it is impossible to believe that such a heterogeneous assemblage of grains could have been dropt into water without the particles being separated and sifted in their progress to the bottom. of course, every one knows that patches and beds of laminated clay and sand of veritable aqueous origin occur now and again in boulder-clay. i suppose there is no boulder-clay without them. i have seen them in the till of italy and switzerland, where they show precisely the same features as the similar laminated clays in the till of our own islands. but these included patches and beds point merely to the action of sub-glacial waters, such as we know circulate under the glaciers of the alps, of norway, and of greenland. again, i would remark that mr. mackintosh has ignored all the evidence which has been brought forward from time to time to demonstrate the sub-glacial origin of boulder-clay, and to prove the utter insufficiency of floating-ice to account for the phenomena. and he adduces no new facts in support of the now discredited iceberg theory, unless it be his statement that _flat_ striated rock-surfaces (such as those near birkenhead) have been caused by floating-ice--the dome-shaped _roches moutonnées_ being, on the other hand the work of land-ice. as a matter of personal observation, i can assure mr. mackintosh that _flat_ striated surfaces are by no means uncommonly associated in one and the same region with _roches moutonnées_. what are _roches moutonnées_ but the rounded relics of what were formerly rough uneven tors, projecting bosses, and prominent rocks? the general tendency of glacial action is to reduce the asperities of a land-surface; hence projecting points are rounded off, while flat surfaces are simply, as a rule, planed smoother. mr. mackintosh might traverse acres of such smoothed rock-surfaces in regions where the strata are comparatively horizontal--for example, in the case of the basaltic plateaux of the faröes and of iceland, which have certainly been glaciated by land-ice. similar flat glaciated surfaces are met with again and again both in the highlands and lowlands of scotland, occupying positions and associated with _roches moutonnées_ and till of such a character as to prove beyond any doubt that they no less certainly are the result of the action of land-ice. but it is needless to discuss the probability or possibility of glaciation of any kind being due to floating-ice. we know that glaciers can and do polish and striate rock-surfaces; no one, however, can say the same of icebergs: and until some one can prove to us that icebergs have performed this feat, or can furnish us with well-considered reasons for believing them to be capable of it, glacialists will continue sceptical. but leaving these and other points which serve to show the weakness of the cause which mr. mackintosh supports with such keen enthusiasm, i may, in conclusion, draw attention to certain very remarkable theoretical views of his which seem to me to be not only self-contradictory, but opposed to well-known natural laws. briefly stated, his general view is that the erratics of the west of england have been distributed by floating-ice during a period of submergence--the scattering of erratics and the accumulation of the associated glacial deposits having commenced at or about the time when the land began to sink, and continued until the submergence reached some feet below the present sea-level. in applying this hypothesis to explain the phenomena, mr. mackintosh makes rather free use of sea-currents and winds. for example, he holds that a current coming from criffel carried with it boulder-laden ice which flowed south-west to the isle of man, south to north wales, and south-east in the direction of blackpool and manchester, liverpool and wolverhampton, dawpool and church stretton. now, in the first place, it is very strange that there is not a vestige or trace of any such submergence, either in the neighbourhood of criffel itself or in the region to the north of it. the whole of that region has been striated and rubbed by land-ice coming down from the watershed of the galloway mountains, to the north of which the striæ, _roches moutonnées_, and tracks followed by erratics, indicate an ice-flow _towards_ the north-west, north, and north-east. it is, therefore, absolutely certain that at the time the granite erratics are supposed to have sailed away from criffel on floating-ice, the whole of the southern uplands of scotland were covered with a great ice-field extending from wigtown to berwickshire; so that, according to mr. mackintosh's hypothesis, we should be forced to believe that an ocean-current originated in criffel itself! but waiving this and other insuperable objections which will occur to any geologist who is familiar with the glacial phenomena of the south of scotland, and confining myself to the evidence supplied by the english drifts, i would remark that mr. mackintosh's hypothesis is not consistent with itself. a current flowing in the direction supposed could not possibly have permitted floating-ice to sail from cumbria to the isle of man, to moel-y-tryfane and colwyn bay. mr. mackintosh admits this himself, but infers that the transport of the cumbrian erratics may have taken place at a different time. but how could this be, seeing that the criffel and cumbrian erratics occur side by side in one and the same deposit? again, the hypothesis of an ocean-current coming from criffel is inconsistent with the presence of the irish chalk-flints in the drifts of the west of england. did these also come at a different time? and what about the dispersion of erratics from great arenig, which have gone north-east and north-north-east, almost exactly in the face of the supposed criffel current? here an ocean-current is obviously out of the question; and accordingly we are told that this dispersion of welsh boulders was probably the result of wind. but why should this wind have propelled the floating-ice so far and no further in an easterly direction? surely if floating-ice was swept outwards from great arenig as far as eryrys, bergs must have been carried now and again much further to the east. and if they did not sail eastwards, what became of them? did they all melt away immediately when they came into the ice-laden current that flowed towards the south-east?[y] a still greater difficulty remains. the criffel and cumbrian erratics suddenly cease when they are followed to the south, great quantities of them being accumulated over a belt of country extending from beyond wolverhampton to bridgenorth. what was it that defined the southern limits of these northern boulders? it is clear that it could not have been high-ground, for the severn valley, not to speak of low-lying regions further to the north-east, must have been submerged according to mr. mackintosh's hypothesis. there was therefore plenty of sea-room for the floating-ice to escape southwards. and yet, notwithstanding this, vast multitudes of bergs and floes, as soon as they arrived at certain points, suddenly melted away and dropt their burdens! in what region under the sun does anything like that happen at the present day? mr. mackintosh thinks that the more or less sharply-defined boundary-line reached by the erratics "could only have resulted from close proximity to a persistent current of water (or air?) sufficiently warm to melt the boulder-laden ice." he does not tell us, however, where this warm current of water or air came from, or in what direction it travelled. he forgets some of his own facts connected with the appearance of erratics of eastern derivation, and which, according to him, point to an ocean-current that flowed across from lincolnshire into the very sea in which the criffel granite and cumbrian boulders were being dropt. the supposed warm ocean-current, then, if such it was rather than air, could hardly have come from the east. neither is it at all likely that it could have come from the west, sheltered as the region of the severn valley must have been by the ice-laden mountains of wales. again, the south is shut to us; for there are no erratics in the south of england from which to infer a submergence of that district. if it be true that all the northern erratics which are scattered over the low-grounds of england, denmark, holland, germany, poland, and russia, owe their origin to boulder-laden ice carried by ocean-currents, no such warm water as mr. mackintosh desiderates could possibly have come from the east or south-east. we are left, then, to infer that the supposed warm current[z] must have flowed up the severn valley directly in the face of the criffel current, underneath which it suddenly plunged at a high temperature, the line of junction between it and the cold water being sharply defined, and retaining its position unchanged for a long period of time! however absurd this conclusion may be, it is forced upon us if we admit the hypothesis at present under review. for we must remember that the floating-ice is supposed to have melted whenever it came into contact with the warm current. the erratics occur up to a certain boundary-line, where they are concentrated in enormous numbers, and south of which they do not appear. here, then, large and small floes alike must have vanished at once! certainly a very extraordinary case of dissolution. [y] mr. mackintosh says nothing about the "carry" or direction of the erratics in west and south wales. were the paths of these erratics delineated upon a map, we should find it necessary to suppose that the wind- or sea-current by which the floating-ice was propelled had flowed outwards in all directions from the dominant heights! [z] it must have likewise flowed in more or less direct opposition to the current which, in accordance with the iceberg hypothesis, transported boulders southwards from the high-grounds of south wales! if we dismiss the notion of a warm ocean-current for that of a warm wind, we do not improve our position a whit. where did the warm wind come from? not, certainly, from the ice-laden seas to the east. are we to suppose, then, that it flowed in from the south or south-west? if so, we might well ask how it came to pass that in the immediate proximity of such a very warm wind as the hypothesis demands, great snow-fields and glaciers were allowed to exist in wales? passing that objection, we have still to ask how this wind succeeded in melting large and small masses of floating-ice with such rapidity that it prevented any of them ever trespassing south of a certain line? it is obvious that it must have been an exceedingly hot wind; and that, just as the hypothetical warm ocean-current must have suddenly dived under the cold water coming from the north, so the hot wind, after passing over the surface of the sea until it reached a certain more or less well-defined line, must have risen all at once and flowed vertically upwards into the cold regions above. thus, in seeking to escape from what he doubtless considers the erroneous and extravagant views of "land-glacialists," mr. mackintosh adopts a hypothesis which lands him in self-contradictions and a perfect "sea of troubles"--a kind of chaos, in fact. in attempting to explain the drifts of western england and east wales he has ignored the conditions that must have obtained in contiguous regions--thus forgetting that "nothing in the world is single," and that one ought not to infer physical conditions for one limited area without stopping to inquire whether these are in consonance with what is known of adjacent districts, or in harmony with the existing phenomena of nature. i have so strongly opposed mr. mackintosh's explanation of the sudden termination of the northern erratics in the neighbourhood of wolverhampton and elsewhere, that perhaps i ought to offer an explanation of my own, that it may, in its turn, undergo examination. i labour under the disadvantage, however, of not having studied the drifts in and around wolverhampton, etc., and the suggestion which i shall throw out must therefore be taken for what it is worth. it seems to me, then, that the concentration of boulders in the neighbourhood of wolverhampton, and the limits reached by the northern erratics generally, mark out, in all probability, the line of junction between the _mer de glace_ coming from the basin of the irish sea and that flowing across the country from the vast _mer de glace_ that occupied the basin of the german ocean. along this line the southerly transport of the northern boulders would cease, and here they would therefore tend to become concentrated. but it is most likely that now and again they would get underneath the ice-flow that set down the severn valley, and i should anticipate that they will yet be detected, along with erratics of eastern origin, as far south even as the bristol channel. if it be objected to this view that erratics from great arenig have been met with south of wolverhampton, at birmingham and bromsgrove, i would reply that these erratics were probably carried south either before or after the general _mer de glace_ had attained its climax--at a period when the welsh ice was able to creep out further to the east than it could when the invasion of the north sea ice was at its height. i cannot conclude this paper without expressing my admiration for the long-continued and successful labours of the well-known geologist whose views i have been controverting. although i have entered my protest against his iceberg hypothesis, and have freely criticised his theoretical opinions, i most willingly admit that the practical results of his unwearied devotion to the study of those interesting phenomena with which he is so familiar have laid all his fellow-workers under a debt of gratitude. viii. recent researches in the glacial geology of the continent.[aa] [aa] presidential address to the geological section of the british association, newcastle, . the president of this section must often have some difficulty in selecting a subject for his address. it is no longer possible to give an interesting and instructive summary of the work done by the devotees of our science during even one year. so numerous have the students of geological science become--so fertile are the fields they cultivate--so abundant the harvests they reap, that one in my present position may well despair of being able to take stock of the numerous additions to our knowledge which have accumulated within the last twelve months. neither is there any burning question which at this time your president need feel called upon to discuss. true, there are controversies that are likely to remain unsettled for years to come--there are still not a few matters upon which we must agree to differ--we do not yet see eye to eye in all things geological. but experience has shown that as years advance truth is gradually evolved, and old controversies die out, and so doubtless it will continue to be. the day when controversies shall cease, however, is yet, i hope, far in the future; for should that dull and unhappy time ever arrive, it is quite certain that mineralogists, petrologists, palæontologists, and geologists shall have died out of the world. following the example of many of my predecessors, i shall confine my remarks to certain questions in which i have been specially interested; and in doing so i shall endeavour to steer clear, as far as i can, of controversial matters. my purpose, then, is to give an outline of some of the results obtained during the last few years by continental workers in the domain of glacial geology. those who are not geologists will probably smile when they hear one declare that wielders of the hammer are extremely conservative--that they are slow to accept novel views, and very tenacious of opinions which have once found favour in their eyes. nevertheless, such is the case, and well for us that it is so. however captivating, however imposing, however strongly supported by evidence a new view may appear to be, we do well to criticise, to sift the evidence, and to call for more facts and experiments, if such are possible, until the proofs become so strong as to approach as near a demonstration as geologists can in most cases expect such proofs to go. the history of our science, and indeed of most sciences, affords abundant illustration of what i say. how many long years were the views of sub-aërial erosion, as taught by hutton and playfair, canvassed and controverted before they became accepted! and even after their general soundness had been established, how often have we heard nominal disciples of these fathers of physical geology refuse to go so far as to admit that the river-valleys of our islands have been excavated by epigene agents! if, as a rule, it takes some time for a novel view to gain acceptance, it is equally true that views which have long been held are only with difficulty discarded. between the new and the old there is a constant struggle for existence, and if the latter should happen to survive, it is only in a modified form. i have often thought that a history of the evolution of geological theories would make a very entertaining and instructive work. we should learn from it, amongst other things, that the advance of our science has not always been continuous--now and again, indeed, it has almost seemed as if the movement had been retrograde. knowledge has not come in like an overwhelming flood--as a broad majestic river--but rather like a gently-flowing tide, now advancing, now retiring, but ever, upon the whole, steadily gaining ground. the history i speak of would also teach us that many of the general views and hypotheses which have been from time to time abandoned as unworkable, are hardly deserving of the reproach and ridicule which we in these latter days may be inclined to cast upon them. as the scots proverb says: "it is easy to be wise behindhand." it could be readily shown that not a few discarded notions and opinions have frequently worked for good, and have rather stimulated than checked inquiry. such reflections should be encouraging to every investigator, whether he be a defender of the old or an advocate of the new. time tries all, and each worker may claim a share in the final establishment of the truth. perhaps there is no department of geological inquiry that has given rise to more controversy than that which i have selected for the subject of this address. hardly a single step in advance has been taken without vehement opposition. but the din of contending sides is not so loud now--the dust of the conflict has to some extent cleared away, and the positions which have been lost or maintained, as the case may be, can be readily discerned. the glacialist who can look back over the last twenty-five years of wordy conflict has every reason to be jubilant and hopeful. many of those who formerly opposed him have come over to his side. it is true he has not had everything his own way. some extreme views have been abandoned in the struggle; that of a great polar ice-sheet, for example, as conceived of by agassiz. i am not aware, however, that many serious students of glacial geology ever adopted that view. but it was quite an excusable hypothesis, and has been abundantly suggestive. had agassiz lived to see the detailed work of these later days, he would doubtless have modified his notion and come to accept the view of large continental glaciers which has taken its place. the results obtained by geologists who have been studying the peripheral areas of the drift-covered regions of our continent, are such as to satisfy us that the drifts of those regions are not iceberg-droppings, as we used to suppose, but true morainic matter and fluvio-glacial detritus. geologists have not jumped to this conclusion--they have only accepted it after laborious investigation of the evidence. since dr. otto torell, in , first stated his belief that the diluvium of north germany was of glacial origin a great literature on the subject has sprung up, a perusal of which will show that with our german friends glacial geology has passed through much the same succession of controversial phases as with us. at first icebergs are appealed to as explaining everything--next we meet with sundry ingenious attempts at a compromise between floating-ice and a continuous ice-sheet. as observations multiply, however, the element of floating-ice is gradually eliminated, and all the phenomena are explained by means of land-ice and "schmelz-wasser" alone. it is a remarkable fact that the iceberg hypothesis has always been most strenuously upheld by geologists whose labours have been largely confined to the peripheral areas of drift-covered countries. in the upland and mountainous tracts, on the other hand, that hypothesis has never been able to survive a moderate amount of accurate observation. even in switzerland--the land of glaciers--geologists at one time were of opinion that the boulder-clays of the low-grounds had a different origin from those which occur in the mountain-valleys. thus, it was supposed that at the close of the pleistocene period the alps were surrounded by great lakes or by gulfs of some inland sea, into which the glaciers of the high valleys flowed and calved their icebergs--these latter scattering erratics and earthy débris over the drowned areas. sartorius von waltershausen[ab] set forth this view in an elaborate and well-illustrated paper. unfortunately for his hypothesis no trace of the supposed great lakes or the inland sea has ever been detected: on the contrary, the character of the morainic accumulations, and the symmetrical grouping and radiation of the erratics and perched blocks over the foot-hills and low-grounds, show that these last have been invaded and overflowed by the glaciers themselves. even the most strenuous upholders of the efficacy of icebergs as originators of some boulder-clays, admit that the boulder-clay or till, of what we may call the inner or central region of a glaciated tract is the product of land-ice. under this category comes the boulder-clay of norway, sweden, and finland, and of the alpine lands of central europe, not to speak of the hilly parts of our own islands. [ab] "untersuchungen über die klimate der gegenwart und der vorwelt," etc.--_natuurkundige verhandelingen v. d. holland. maatsch. d. wetensch. te haarlem_, . when we come to study the drifts of the peripheral areas, it is not difficult to see why these should be considered to have had a different origin. they present certain features which, although not absent from the glacial deposits of the inner region, are not nearly so characteristic of such upland tracts. i refer especially to the frequent interstratification of boulder-clays with well-bedded deposits of clay, sand, and gravel; and to the fact that these boulder-clays are often less compressed than those of the inner region, and have even occasionally a silt-like character. such appearances do seem at first to be readily explained on the assumption that the deposits have been accumulated in water opposite the margin of a continental glacier or ice-sheet--and this was the view which several able investigators in germany were for some time inclined to adopt. but when the phenomena came to be studied in greater detail, and over a wider area, this preliminary hypothesis did not prove satisfactory. it was discovered, for example, that "giants' kettles"[ac] were more or less commonly distributed under the glacial deposits, and such "kettles" could only have originated at the bottom of a glacier. again, it was found that pre-glacial accumulations were plentifully developed in certain places below the drift, and were often involved with the latter in a remarkable way. the "brown-coal formation" in like manner was violently disturbed and displaced, to such a degree that frequently the boulder-clay is found to underlie it. similar phenomena were encountered in regions where the drift overlies the chalk--the latter presenting the appearance of having been smashed and shattered--the fragments having often been dragged some distance, so as to form a kind of friction-breccia underlying the drift, while large masses are often included in the clay itself. all the facts pointed to the conclusion that these disturbances were due to tangential thrusting or crushing, and were not the result of vertical displacements, such as are produced by normal faulting, for the disturbances in question die out from above downwards. evidence of similar thrusting or crushing is seen in the remarkable faults and contortions that so often characterise the clays and sands that occur in the boulder-clay itself. the only agent that could produce the appearances, now briefly referred to, is land-ice, and we must therefore agree with german geologists that glacier-ice has overflowed all the drift-covered regions of the peripheral area. no evidence of marine action in the formation of the stony clays is forthcoming--not a trace of any sea-beach has been detected. and yet, if these clays had been laid down in the sea during the retreat of the ice-sheet from germany, surely such evidence as i have indicated ought to be met with. to the best of my knowledge the only particular facts which have been appealed to, as proofs of marine action, are the appearance of bedded deposits in the boulder-clays, and the occasional occurrence in the clays themselves of a sea-shell. but other organic remains are also met with now and again in similar positions, such as mammalian bones and freshwater shells. all these, however, have been shown to be derivative in their origin--they are just as much erratics as the stones and boulders with which they are associated. the only phenomena, therefore, that the glacialist has to account for are the bedded deposits which occur so frequently in the boulder-clays of the peripheral regions, and the occasional silty and uncompressed character of the clays themselves. [ac] these appear to have been first detected by professor berendt and professor e. geinitz. the intercalated beds are, after all, not hard to explain. if we consider for a moment the geographical distribution of the boulder-clays, and their associated aqueous deposits, we shall find a clue to their origin. speaking in general terms, the stony clays thicken out as they are followed from the mountainous and high-lying tracts to the low-grounds. thus they are of inconsiderable thickness in norway, the higher parts of sweden, and in finland, just as we find is the case in scotland, northern england, wales, and the hilly parts of ireland. traced south from the uplands of scandinavia and finland, they gradually thicken out as the low-grounds are approached. thus in southern sweden they reach a thickness of metres or thereabout, and of metres in the northern parts of prussia, while over the wide low-lying regions to the south they attain a much greater thickness--reaching in holstein, mecklenburg, pomerania, and west prussia, a depth of to metres, and still greater depths in hanover, mark brandenburg, and saxony. in those regions, however, a considerable portion of the diluvium consists, as we shall see presently, of water-formed beds. the geographical distribution of the aqueous deposits, which are associated with the stony clays, is somewhat similar. they are very sparingly developed in districts where the boulder-clays are thin. thus they are either wanting, or only occur sporadically in thin irregular beds, in the high-grounds of northern europe generally. further south, however, they gradually acquire more importance, until in the peripheral regions of the drift-covered tracts they come to equal and eventually to surpass the boulder-clays in prominence. these latter, in fact, at last cease to appear, and the whole bulk of the diluvium, along the southern margin of the drift area, appears to consist of aqueous accumulations alone. the explanations of these facts advanced by german geologists are quite in accordance with the views which have long been held by glacialists elsewhere, and have been tersely summed up by dr. jentzsch.[ad] the northern regions, he says, were the feeding-grounds of the inland-ice. in those regions melting was at a minimum, while the grinding action of the ice was most effective. here, therefore, erosion reached its maximum--ground-moraine or boulder-clay being unable to accumulate to any thickness. further south melting greatly increased, while ground-moraine at the same time tended to accumulate--the conjoint action of glacier-ice and sub-glacial water resulting in the complex drifts of the peripheral area. in the disposition and appearance of the aqueous deposits of the diluvium we have evidence of an extensive sub-glacial water-circulation--glacier-mills that gave rise to "giants' kettles"--chains of sub-glacial lakes in which fine clays gathered--streams and rivers that flowed in tunnels under the ice, and whose courses were paved with sand and gravel. nowhere do german geologists find any evidence of marine action. on the contrary, the dovetailing and interosculation of boulder-clay with aqueous deposits are explained by the relation of the ice to the surface over which it flowed. throughout the peripheral area it did not rest so continuously upon the ground as was the case in the inner region of maximum erosion. in many places it was tunnelled by rapid streams and rivers, and here and there it arched over sub-glacial lakes, so that accumulation of ground-moraine proceeded side by side with the formation of aqueous sediments. much of that ground-moraine is of the usual tough and hard-pressed character, but here and there it is somewhat less coherent and even silt-like. now a study of the ground-moraines of modern glaciers affords us a reasonable explanation of such differences. dr. brückner[ae] has shown that in many places the ground-moraine of the alpine glaciers is included in the bottom of the ice itself. the ground-moraine, he says, frequently appears as an ice-stratum abundantly impregnated with silt and rock-fragments--it is like a conglomerate or breccia which has ice for its binding material. when this ground-moraine melts out of the ice--no running water being present--it forms a layer of unstratified silt or clay, with stones scattered irregularly through it. such being the case in modern glaciers, we can hardly doubt that over the peripheral areas occupied by the old northern ice-sheet boulder-clay must frequently have been accumulated in the same way. nay, when the ground-moraine melted out and dropt here and there into quietly-flowing water it might even acquire in part a bedded character. [ad] _jahrb. d. königl. preuss. geologischen landesanstalt für _, p. . [ae] "die vergletscherung des salzachgebietes, etc.": _geographische abhandlungen herausgegeben v. a. penck_, band i. heft . the limits reached by the inland-ice during its greatest extension are becoming more and more clearly defined, although its southern margin will probably never be so accurately determined as that of the latest epoch of general glaciation. the reasons for this are obvious. when the inland-ice flowed south to the harz and the hills of saxony it formed no great terminal moraines. doubtless many erratics and much rock-rubbish were showered upon the surface of the ice from the higher mountains of scandinavia, but owing to the fanning-out of the ice on its southward march, such superficial débris was necessarily spread over a constantly-widening area. it may well be doubted, therefore, whether it ever reached the terminal front of the ice-sheet in sufficient bulk to form conspicuous moraines. it seems most probable that the terminal moraines of the great inland-ice would consist of low banks of boulder-clay and aqueous materials-the latter, perhaps, strongly predominating, and containing here and there larger and smaller angular erratics which had travelled on the surface of the ice. however that may be, it is certain that the whole region in question has been considerably modified by subsequent denudation, and to a large extent is now concealed under deposits belonging to later stages of the pleistocene period. the extreme limits reached by the ice are determined rather by the occasional presence of rock-striæ and _roches moutonnées_, of boulder-clay and northern erratics, than by recognisable terminal moraines. the southern limits reached by the old inland-ice appear in this way to have been tolerably well ascertained over a considerable portion of central europe. some years ago i published a small sketch-map[af] showing the extent of surface formerly covered by ice. on this map i did not venture to draw the southern margin of the ice-sheet in belgium further south than antwerp, where northern erratics were known to occur, but the more recent researches of belgian geologists show that the ice probably flowed south for some little distance beyond brussels.[ag] here and there in other parts of the continent the southern limits reached by the northern drift have also been more accurately determined, but, so far as i know, none of these later observations involves any serious modification of the sketch-map referred to. [af] _prehistoric europe_, . [ag] see a paper by m. e. delvaux: _ann. de la. soc. géol. de belg._, t. xiii. p. . i have now said enough, however, to show that the notion of a general ice-sheet having covered so large a part of europe, which a few years ago was looked upon as a wild dream, has been amply justified by the labours of those who are so assiduously investigating the peripheral areas of the "great northern drift." and perhaps i may be allowed to express my own belief that the drifts of middle and southern england, which exhibit the same complexity as the lower diluvium of the continent, will eventually be generally acknowledged to have had a similar origin. i have often thought that whilst politically we are happy in having the sea all round us, geologically we should have gained perhaps by its greater distance. at all events we should have been less ready to invoke its assistance to explain every puzzling appearance presented by our glacial accumulations. i now pass on to review some of the general results obtained by continental geologists as to the extent of area occupied by inland-ice during the last great extension of glacier-ice in europe. it is well known that this latest ice-sheet did not overflow nearly so wide a region as that underneath which the lowest boulder-clay was accumulated. this is shown not only by the geographical distribution of the youngest boulder-clay, but by the direction of rock-striæ, the trend of erratics, and the position of well-marked terminal moraines. gerard de geer has given a summary[ah] of the general results obtained by himself and his fellow-workers in sweden and norway; and these have been supplemented by the labours of berendt, e. geinitz, hauchecorne, keilhack, klockmann, schröder, wahnschaffe, and others in germany, and by sederholm in finland.[ai] from them we learn that the end-moraines of the ice circle round the southern coasts of norway, from whence they sweep south-east by east across the province of gottland in sweden, passing through the lower ends of lakes wener and wetter, while similar moraines mark out for us the terminal front of the inland-ice in finland--at least two parallel frontal moraines passing inland from hango head on the gulf of finland through the southern part of that province to the north of lake ladoga. further north-east than this they have not been traced; but, from some observations by helmersen, sederholm thinks it probable that the terminal ice-front extended north-east by the north of lake onega to the eastern shores of the white sea. between sweden and finland lies the basin of the baltic, which at the period in question was filled with ice, forming a great baltic glacier which overflowed the Öland islands, gottland, and Öland, and which, fanning-out as it passed towards the south-west, invaded, on the south side, the baltic provinces of germany, while, on the north, it crossed the southern part of scania in sweden and the danish islands to enter jutland. [ah] _zeitschrift d. deutsch. geolog. ges._, bd. xxxvii., p. . [ai] for papers by berendt and his associates see especially the _jahrbuch d. k. preuss. geol. landesanstalt_, and the _zaitschr. d. deutsch. geol. ges._ for the past few years. geinitz: _forsch. z. d. lands- u. volkskunde_, i. ; _leopoldina_, xxii., p. ; i. _beitrag z. geologie mecklenburgs_, , pp. , . sederholm: _fennia_, i. no. . the upper boulder-clay of those regions is now recognised as the ground-moraine of this latest ice-sheet. in many places it is separated from the older boulder-clay by interglacial deposits--some of which are marine, while others are of freshwater and terrestrial origin. during interglacial times the sea that overflowed a considerable portion of north germany was evidently continuous with the north sea, as is shown not only by the geographical distribution of the interglacial marine deposits, but by their north sea fauna. german geologists generally group all the interglacial deposits together, as if they belonged to one and the same interglacial epoch. this perhaps we must look upon as only a provisional arrangement. certain it is that the freshwater and terrestrial beds which frequently occur on the same or a lower level, and at no great distance from the marine deposits, cannot in all cases be contemporaneous with the latter. possibly, however, such discordances may be accounted for by oscillations in the level of the interglacial sea--land and water having alternately prevailed over the same area. two boulder-clays, as we have seen, have been recognised over a wide region in the north of germany. in some places, however, three or more such boulder-clays have been observed overlying one another throughout considerable areas, and these clays are described as being distinctly separate and distinguishable the one from the other.[aj] whether they, with their intercalated aqueous deposits, indicate great oscillations of one and the same ice-sheet--now advancing, now retreating--or whether the stony clays may not be the ground-moraines of so many different ice-sheets, separated the one from the other by true interglacial conditions, future investigations must be left to decide. [aj] h. schröder: _jahrb. d. k. preuss. geol. landesanstalt für _ , p. . the general conclusions arrived at by those who are at present investigating the glacial accumulations of northern europe may be summarised as follows:-- . before the invasion of northern germany by the inland-ice the low-grounds bordering on the baltic were overflowed by a sea which contained a boreal and arctic fauna. these marine conditions are indicated by the presence under the lower boulder-clay of more or less well-bedded fossiliferous deposits. on the same horizon occur also beds of sand, containing freshwater shells, and now and again mammalian remains, some of which imply cold and others temperate climatic conditions. obviously all these deposits may pertain to one and the same period, or more properly to different stages of the same period--some dating back to a time when the climate was still temperate, while others clearly indicate the prevalence of cold conditions, and are therefore probably somewhat younger. . the next geological horizon in ascending order is that which is marked by the lower diluvium--the glacial and fluvio-glacial detritus of the great ice-sheet which flowed south to the foot of the harz mountains. the boulder-clay on this horizon now and again contains marine, freshwater, and terrestrial organic remains--derived undoubtedly from the so-called pre-glacial beds already referred to. these latter, it would appear, were ploughed up and largely incorporated with the old ground-moraine. . the interglacial beds which next succeed contain remains of a well-marked temperate fauna and flora, which point to something more than a mere partial or local retreat of the inland-ice. the geographical distribution of the beds, and the presence in these of such forms as _elephas antiquus_, _cervus elephas_, _c. megaceros_, and a flora comparable to that now existing in northern germany, justify geologists in concluding that the interglacial epoch was one of long duration, and characterised in germany by climatic conditions apparently not less temperate than those that now obtain. one of the phases of that interglacial epoch, as we have seen, was the overflowing of the baltic provinces by the waters of the north sea. . to this well-marked interglacial epoch succeeded another epoch of arctic conditions, when the scandinavian inland-ice once more invaded germany, ploughing through the interglacial deposits, and working these up in its ground-moraine. so far as i can learn, the prevalent belief among geologists in north germany is that there was only one interglacial epoch; but, as already stated, doubt has been expressed whether all the facts can be thus accounted for. there must always be great difficulty in the correlation of widely-separated interglacial deposits, and the time does not seem to me to have yet come when we can definitely assert that all those interglacial beds belong to one and the same geological horizon. i have dwelt upon the recent work of geologists in the peripheral areas of the drift-covered regions of northern europe, because i think the results obtained are of great interest to glacialists in this country. and for the same reason i wish next to call attention to what has been done of late years in elucidating the glacial geology of the alpine lands of central europe--and more particularly of the low-grounds that stretch out from the foot of the mountains. any observations that tend to throw light upon the history of the complex drifts of our own peripheral areas cannot but be of service. it is quite impossible to do justice in this brief sketch to the labours of the many enthusiastic geologists who within recent years have increased our knowledge of the glaciation of the alpine lands. at present, however, i am not so much concerned with the proofs of general glaciation as with the evidence that goes to show how the alpine ground-moraines have been formed, and with the facts which have led certain observers to conclude that the alps have endured several distinct glaciations within pleistocene times. swiss geologists are agreed that the ground-moraines which clothe the bottoms of the great alpine valleys, and extend outwards sometimes for many miles upon the low-grounds beyond, are of true glacial origin. now these ground-moraines are closely similar to the boulder-clays of this country and northern europe--like them, they are frequently tough and hard-pressed, but now and again somewhat looser, and less firmly coherent. frequently also they contain lenticular beds, and more or less thick sheets of aqueous deposits--in some places the stony clays even exhibiting a kind of stratification--and ever and anon such water-assorted materials are commingled with stony clay in the most complex manner. these latter appearances are, however, upon the whole best developed upon the low-grounds that sweep out from the base of the alps. the only question concerning the ground-moraines that has recently given rise to much discussion is the origin of the materials themselves. it is obvious that there are only three possible modes in which those materials could have been introduced to the ground-moraine: either they consist of superficial morainic débris which has found its way down to the bottom of the old glaciers by crevasses; or they may be made up of the rock-rubbish, shingle, gravel, etc., which doubtless strewed the valleys before these were occupied by ice; or, lastly, they may have been derived in chief measure from the underlying rocks themselves by the action of the ice that overflowed them. the investigations of penck, blaas, böhm, and brückner appear to me to have demonstrated that the ground-moraines are composed mostly of materials which have been detached from the underlying rocks by the erosive action of the glaciers themselves. their observations show that the regions studied by them in great detail were almost completely buried under ice--so that the accumulation of superficial moraines was for the most part impossible; and they advance a number of facts which prove positively that the ground-moraines were formed and accumulated under ice. i cannot here recapitulate the evidence, but must content myself by a reference to the papers in which this is fully discussed.[ak] these geologists do not deny that some of the material may occasionally have come from above, nor do they doubt that pre-existing masses of rock-rubbish and alluvial accumulations may also have been incorporated with the ground-moraines; but the enormous extent of the latter, and the direction of transport and distribution of the erratics which they contain cannot be thus accounted for, while all the facts are readily explained by the action of the ice itself, which used its sub-glacial débris as tools with which to carry on the work of erosion. [ak] penck: _die vergletscherung der deutschen alpen._ blaas: _zeitschrift d. ferdinandeums_, . böhm: _jahrb. d. k. k. geol. reichsanstalt_, , bd. xxxv., heft . brückner: _die vergletscherung d. salzachgebietes, etc._, . professor heim and others have frequently asserted that glaciers have little or no eroding power, since at the lower ends of existing glaciers we find no evidence of such erosion being in operation. but the chief work of a glacier cannot be carried on at its lower end, where motion is reduced to a minimum, and where the ice is perforated by sub-glacial tunnels and arches, underneath which no glacial erosion can possibly take place; and yet it is upon observations made in just such places that the principal arguments against the erosive action of glaciers have been based. if all that we could ever know of glacial action were confined to what we can learn from peering into the grottoes at the terminal fronts of existing glaciers, we should indeed come to the conclusion that glaciers do not erode their rocky beds to any appreciable extent. but as we do not look for the strongest evidence of fluviatile erosion at the mouth of a river, but in its valley--and mountain-tracks, so if we wish to learn what glacier-ice can accomplish, we must study in detail some wide region from which the ice has completely disappeared. when this plan has been followed, it has happened that some of the strongest opponents of glacial erosion have been compelled by the force of the evidence to go over to the other camp. dr. blaas, for example, has been led by his observations on the glacial formations of the inn valley to recant his former views, and to become a formidable advocate of the very theory which he formerly opposed. to his work and the memoirs by penck, brückner, and böhm already cited, and especially to the admirable chapter on glacier-erosion by the last-named author, i would refer those who may be anxious to know the last word on this much-debated question. the evidence of interglacial conditions within the alpine lands continues to increase. these are represented by alluvial deposits of silt, sand, gravel, conglomerate, breccia, and lignites. penck, böhm, and brückner find evidence of two interglacial epochs, and maintain that there have been three distinct and separate epochs of glaciation in the alps. no mere temporary retreat and re-advance of the glaciers, according to them, will account for the various phenomena presented by the interglacial deposits and associated morainic accumulations. during interglacial times the glaciers disappeared from the lower valleys of the alps--the climate was temperate, and probably the snow-fields and glaciers approximated in extent to those of the present day. all the evidence conspires to show that an interglacial epoch was of prolonged duration. dr. brückner has observed that the moraines of the last glacial epoch rest here and there upon löss, and he confirms penck's observations in south bavaria that this remarkable formation never overlies the morainic accumulations of the latest glacial epoch. according to penck and brückner, therefore, the löss is of interglacial age. there can be little doubt, however, that löss does not belong to any one particular horizon. wahnschaffe[al] and others have shown that throughout wide areas in north germany it is the equivalent in age of the upper diluvium, while schumacher[am] points out that in the rhine valley it occurs on two separate and distinct horizons. professor andreæ has likewise shown[an] that there is an upper and lower löss in alsace--each characterised by its own special fauna. [al] _abhandl. z. geol. specialkarte v. preussen_, etc., bd. vii. heft ; _zeitschr. d. zeutsch. geol. ges._, , p. ; , p. . [am] _hygienische topographie von strassburg i. e._, . [an] _abhandl. z. geol. specialkarte a. elsass-lothringen_, bd. iv. heft . there is still considerable difference of opinion as to the mode of formation of this remarkable accumulation. by many it is considered to be an aqueous deposit; others, following richthofen, are of opinion that it is a wind-blown accumulation; while some incline to the belief that it is partly the one and partly the other. nor do the upholders of these various hypotheses agree amongst themselves as to the precise manner in which water or wind has worked to produce the observed results. thus, amongst the supporters of the aqueous origin of the löss, we find this attributed to the action of heavy rains washing over and rearranging the material of the boulder-clays.[ao] many, again, have held it probable that löss is simply the finest loam distributed over the low-grounds by the flood-waters that escaped from the northern inland-ice and the _mers de glace_ of the alpine lands of central europe. another suggestion is that much of the material of the löss may have been derived from the denudation of the boulder-clays by flood-water, during the closing stages of the last cold period. it is pointed out that in some regions, at least, the löss is underlaid by a layer of erratics, which are believed to be the residue of the denuded boulder-clay. we are reminded by klockmann[ap] and wahnschaffe[aq] that the inland-ice must have acted as a great dam, and that wide areas in germany, etc., would be flooded, partly by water derived from the melting inland-ice, and partly by waters flowing north from the hilly tracts of middle germany. in the great basins thus formed there would be a commingling of fine silt material derived from north and south, which would necessarily come to form a deposit having much the same character throughout. [ao] laspeyres: _erläuterungen z. geol specialkaret v preussen_, etc., _blatt. gröbzig, zörbig, und petersberg_. [ap] klockmann: _jahrb. d. k. preuss. geol. landesanstalt für _, p. . [aq] wahnschaffe: _op. cit._, and _zeitschr. d. deutsch. geol. ges._, , p. . from what i have myself seen of the löss in various parts of germany, and from all that i have gathered from reading and in conversation with those who have worked over löss-covered regions, i incline to the opinion that löss is for the most part of aqueous origin. in many cases this can be demonstrated, as by the occurrence of bedding and the intercalation of layers of stones, sand, gravel, etc., in the deposit; again, by the not infrequent appearance of freshwater shells; but, perhaps, chiefly by the remarkable uniformity of character which the löss itself displays. it seems to me reasonable also to believe that the flood-waters of glacial times must needs have been highly charged with finely-divided sediment, and that such sediment would be spread over wide regions in the low-grounds--in the slackwaters of the great rivers and in the innumerable temporary lakes which occupied, or partly occupied, many of the valleys and depressions of the land. there are different kinds of löss or löss-like deposits, however, and all need not have been formed in the same way. probably some may have been derived, as wahnschaffe has suggested, from denudation of boulder-clay. possibly also, some löss may owe its origin to the action of rain on the stony clays, producing what we in this country would call "rain-wash." there are other accumulations, however, which no aqueous theory will satisfactorily explain. under this category comes much of the so-called _berglöss_, with its abundant land-shells, and its generally unstratified character. it seems likely that such löss is simply the result of sub-aërial action, and owes its origin to rain, frost, and wind acting upon the superficial formations, and rearranging their finer-grained constituents. and it is quite possible that the upper portion of much of the löss of the lower-grounds may have been re-worked in the same way. but i confess i cannot yet find in the facts adduced by german geologists any evidence of a dry-as-dust epoch having obtained in europe during any stage of the pleistocene period. the geographical position of our continent seems to me to forbid the possibility of such climatic conditions, while all the positive evidence we have points to humidity rather than dryness as the prevalent feature of pleistocene climates. it is obvious, however, that after the flood-waters had disappeared from the low-grounds of the continent, sub-aërial action would come into play over the wide regions covered by the glacial and fluvio-glacial deposits. thus, in the course of time, these deposits would become modified,--just as similar accumulations in these islands have been top-dressed, as it were, and to some extent even rearranged. i am strengthened in these views by the conclusions arrived at by m. falsan--the eminent french glacialist. covering the plateaux of the dombes, and widely spread throughout the valleys of the rhone, the ain, the isère, etc., in france there is a deposit of löss, he says, which has been derived from the washing of the ancient moraines. at the foot of the alps, where black schists are largely developed, the löss is dark grey, but west of the secondary chain the same deposit is yellowish, and composed almost entirely of silicious materials, with only a very little carbonate of lime. this _limon_ or löss, however, is very generally modified towards the top by the chemical action of rain--the yellow löss acquiring a red colour. sometimes it is crowded with calcareous concretions, but at other times it has been deprived of its calcareous element and converted into a kind of pulverulent silica or quartz. this, the true löss, is distinguished from another _lehm_, which falsan recognises as the product of atmospheric action--formed, in fact, _in situ_, from the disintegration and decomposition of the subjacent rocks. even this lehm has been modified by running water--dispersed or accumulated locally, as the case may be.[ar] [ar] falsan: _la période glaciaire_, p. . all that we know of the löss and its fossils compels us to include this accumulation as a product of the pleistocene period. it is not of post-glacial age--even much of what one may call the "remodified löss" being of late glacial or pleistocene age. i cannot attempt to give here a summary of what has been learned within recent years as to the fauna of the löss. the researches of nehring and liebe have familiarised us with the fact that, at some particular stage in the pleistocene period, a fauna like that of the alpine steppe-lands of western asia was indigenous to middle europe, and the recent investigations by woldrich have increased our knowledge of this fauna. at what horizon, then, does this steppe-fauna make its appearance? at thiede dr. nehring discovered in so-called löss three successive horizons, each characterised by a special fauna. the lowest of these faunas was decidedly arctic in type; above that came a steppe-fauna, which last was succeeded by a fauna comprising such forms as mammoth, woolly rhinoceros, _bos_, _cervus_, horse, hyæna, and lion. now, if we compare this last fauna with the forms which have been obtained from true post-glacial deposits--those deposits, namely, which overlie the younger boulder-clays and flood-accumulations of the latest glacial epoch, we find little in common. the lion, the mammoth, and the rhinoceros are conspicuous by their absence from the post-glacial beds of europe. in place of them we meet with a more or less arctic fauna, and a high-alpine and arctic flora, which as we all know eventually gave place to the flora and fauna with which neolithic man was contemporaneous. as this is the case throughout north-western and central europe, we seem justified in assigning the thiede beds to the pleistocene period, and to that interglacial stage which preceded and gradually merged into the last glacial epoch. that the steppe-fauna indicates relatively drier conditions of climate than obtained when perennial snow and ice covered wide areas of the low-ground goes without saying, but i am unable to agree with those who maintain that it implies a dry-as-dust climate, like that of some of the steppe-regions of our own day. the remarkable commingling of arctic- and steppe-faunas discovered in the böhmer-wald[as] by woldrich shows, i think, that the jerboas, marmots, and hamster-rats were not incapable of living in the same regions contemporaneously with lemmings, arctic hares, siberian social voles, etc. but when a cold epoch was passing away the steppe-forms probably gradually replaced their arctic congeners, as these migrated northwards during the continuous amelioration of the climate. [as] woldrich: _sitzungsb. d. kais. akad. d. w. math. nat. cl._, , p. ; , p. ; , p. . if the student of the pleistocene faunas has certain advantages in the fact that he has to deal with forms many of which are still living, he labours at the same time under disadvantages which are unknown to his colleagues who are engaged in the study of the life of far older periods. the pleistocene period was distinguished above all things by its great oscillations of climate--the successive changes being repeated and producing correlative migrations of floras and faunas. we know that arctic and temperate faunas and floras flourished during interglacial times, and a like succession of life-forms followed the final disappearance of glacial conditions. a study of the organic remains met with in any particular deposit will not necessarily, therefore, enable us to assign these to their proper horizon. the geographical position of the deposit, and its relation to pleistocene accumulations elsewhere, must clearly be taken into account. already, however, much has been done in this direction, and it is probable that ere long we shall be able to arrive at a fair knowledge of the various modifications which the pleistocene floras and faunas experienced during that protracted period of climatic changes of which i have been speaking. we shall even possibly learn how often the arctic, steppe-, prairie-, and forest-faunas, as they have been defined by woldrich, replaced each other. even now some approximation to this better knowledge has been made. dr. pohlig,[at] for example, has compared the remains of the pleistocene faunas obtained at many different places in europe, and has presented us with a classification which, although confessedly incomplete, yet serves to show the direction in which we must look for further advances in this department of inquiry. [at] pohlig: _sitzungsb. d. niederrheinischen gesellschaft zu bonn_, ; _zeitschr. d. deutsch. geolog. ges._, , p. . for a very full account of the diluvial european and northern asiatic mammalian faunas by woldrich, see _mém. de l'acad. des sciences de st. pétersbourg_, vii^e sér., t. xxxv., . during the last twenty years the evidence of interglacial conditions both in europe and america has so increased that geologists generally no longer doubt that the pleistocene period was characterised by great changes of climate. the occurrence at many different localities on the continent of beds of lignite and freshwater alluvia, containing remains of pleistocene mammalia, intercalated between separate and distinct boulder-clays has left us no other alternative. the interglacial beds of the alpine lands of central europe are paralleled by similar deposits in britain, scandinavia, germany, and france. but opinions differ as to the number of glacial and interglacial epochs--many holding that we have evidence of only two cold stages and one general interglacial stage. this, as i have said, is the view entertained by most geologists who are at work on the glacial accumulations of scandinavia and north germany. on the other hand, dr. penck and others, from a study of drifts of the german alpine lands, believe that they have met with evidence of three distinct epochs of glaciation, and two epochs of interglacial conditions. in france, while some observers are of opinion that there have been only two epochs of general glaciation, others, as, for example, m. tardy, find what they consider to be evidence of several such epochs. others again, as m. falsan, do not believe in the existence of any interglacial stages, although they readily admit that there were great advances and retreats of the ice during the glacial period. m. falsan, in short, believes in oscillations, but is of opinion that these were not so extensive as others have maintained. it is, therefore, simply a question of degree, and whether we speak of oscillations or of epochs, we must needs admit the fact that throughout all the glaciated tracts of europe, fossiliferous deposits occur intercalated among glacial accumulations. the successive advance and retreat of the ice, therefore, was not a local phenomenon, but characterised all the glaciated areas. and the evidence shows that the oscillations referred to were on a gigantic scale. the relation borne to the glacial accumulations by the old river alluvia which contain relics of palæolithic man early attracted attention. from the fact that these alluvia in some places overlie glacial deposits, the general opinion (still held by some) was that palæolithic man must needs be of post-glacial age. but since we have learned that all boulder-clay does not belong to one and the same geological horizon--that, in short, there have been at least two, and probably more, epochs of glaciation--it is obvious that the mere occurrence of glacial deposits underneath palæolithic gravels does not prove these latter to be post-glacial. all that we are entitled in such a case to say is simply that the implement-bearing beds are younger than the glacial accumulations upon which they rest. their horizon must be determined by first ascertaining the relative position in the glacial series of the underlying deposits. now, it is a remarkable fact that the boulder-clays which underlie such old alluvia belong, without exception, to the earlier stages of the glacial period. this has been proved again and again, not only for this country but for europe generally. i am sorry to reflect that some twenty years have now elapsed since i was led to suspect that the palæolithic deposits were not of post-glacial but of glacial and interglacial age. in - i published a series of papers in the _geological magazine_ in which were set forth the views i had come to form upon this interesting question. in these papers it was maintained that the alluvia and cave-deposits could not be of post-glacial age, but must be assigned to pre-glacial and interglacial times, and in chief measure to the latter. evidence was led to show that the latest great development of glacier-ice in europe took place after the southern pachyderms and palæolithic man had vacated england--that during this last stage of the glacial period man lived contemporaneously with a northern and alpine fauna in such regions as southern france--and lastly, that palæolithic man and the southern mammalia never revisited north-western europe after extreme glacial conditions had disappeared. these conclusions were arrived at after a somewhat detailed examination of all the evidence then available--the remarkable distribution of the palæolithic and ossiferous alluvia having, as i have said, particularly impressed me. i coloured a map to show at once the areas covered by the glacial and fluvio-glacial deposits of the last glacial epoch, and the regions in which the implement-bearing and ossiferous alluvia had been met with, when it became apparent that the latter never occurred at the surface within the regions occupied by the former. if ossiferous alluvia did here and there appear within the recently glaciated areas it was always either in caves, or as infra- or interglacial deposits. since the date of these researches our knowledge of the geographical distribution of pleistocene deposits has greatly increased, and implements and other relics of palæolithic man have been recorded from many new localities throughout europe. but none of this fresh evidence contradicts the conclusions i had previously arrived at; on the contrary, it has greatly strengthened my general argument. professor penck was, i think, the first on the continent to adopt the views referred to. he was among the earliest to recognise the evidence of interglacial conditions in the drift-covered regions of northern germany, and it was the reflections which those remarkable interglacial beds were so well calculated to suggest that led him into the same path as myself. dr. penck has published a map[au] showing the areas covered by the earlier and later glacial deposits in northern europe and the alpine lands, and indicating at the same time the various localities where palæolithic finds have occurred, and in not a single case do any of the latter appear within the areas covered by the accumulations of the last glacial epoch. [au] _archiv für anthropologie_, bd. xv. heft , . a glance at the papers which have been published in germany within the last few years will show how greatly students of the pleistocene ossiferous beds have been influenced by what is now known of the interglacial deposits and their organic remains. professors rothpletz[av] and andreæ,[aw] dr. pohlig[ax] and others, do not now hesitate to correlate with those beds the old ossiferous and implement-bearing alluvia which lie altogether outside of glaciated regions. [av] rothpletz: _denkschrift d. schweizer. ges. für d. gesammt. nat._, bd. xxviii. . [aw] andreæ: _abhandl. z. geolog. specialkarte v. elsass-lothringen_, bd. iv. heft , . [ax] pohlig: _op. cit._ the relation of the pleistocene alluvia of france to the glacial deposits of that and other countries has been especially canvassed. rothpletz, in the paper i have cited, includes these alluvia amongst the interglacial deposits, and in the present year ( ) we have an interesting essay on the same subject by the accomplished secretary of the anthropological and archæological congress which met recently in paris. m. boule[ay] correlates the palæolithic cave- and river-deposits of france with those of other countries, and shows that they must be of interglacial age. his classification, i am gratified to find, does not materially differ from that given by myself a number of years ago. he is satisfied that in france there is evidence of three glacial epochs and two well-marked interglacial horizons. the oldest of the palæolithic stages of mortillet (chelléenne) culminated according to boule during the last interglacial epoch, while the more recent palæolithic stages (moustérienne, solutréenne, and magdalénienne) coincided with the last great development of glacier-ice. the palæolithic age, so far as europe is concerned, came to a close during this last cold phase of the glacial period. [ay] boule: _revue d'anthropologie_, , t. . there are many other points relating to glacial geology which have of late years been canvassed by continental workers, but these i cannot discuss here. i have purposely indeed restricted my remarks to such parts of a wide subject as i thought might have interest for glacialists in this country, some of whom may not have had their attention directed to the results which have recently been attained by their fellow-labourers in other lands. had time permitted i should gladly have dwelt upon the noteworthy advances made by our american brethren in the same department of inquiry. especially should i have wished to direct attention to the remarkable evidence adduced in favour of the periodicity of glacial action. thus messrs. chamberlin and salisbury, after a general review of that evidence, maintain that the ice age was interrupted by one chief interglacial epoch and also by three interglacial sub-epochs or episodes of deglaciation. these authors discuss at some length the origin of the löss, and come to the general conclusion that while deposits of this character may have been formed at different stages of the glacial period, and under different conditions, yet upon the whole they are best explained by aqueous action. indeed a perusal of the recent geological literature of america shows a close accord between the theoretical opinions of many transatlantic and european geologists. thus as years advance the picture of pleistocene times becomes more and more clearly developed. the conditions under which our old palæolithic predecessors lived--the climatic and geographical changes of which they were the witnesses--are gradually being revealed with a precision that only a few years ago might well have seemed impossible. this of itself is extremely interesting, but i feel sure that i speak the conviction of many workers in this field of labour when i say that the clearing up of the history of pleistocene times is not the only end which they have in view. one can hardly doubt that when the conditions of that period and the causes which gave rise to these have been more fully and definitely ascertained we shall have advanced some way towards the better understanding of the climatic conditions of still earlier periods. for it cannot be denied that our knowledge of palæozoic, mesozoic, and even early cainozoic climates is unsatisfactory. but we may look forward to the time when much of this uncertainty will disappear. meteorologists are every day acquiring a clearer conception of the distribution of atmospheric pressure and temperature and the causes by which that distribution is determined, and the day is approaching when we shall be better able than we are now to apply this extended meteorological knowledge to the explanation of the climates of former periods in the world's history. one of the chief factors in the present distribution of atmospheric temperature and pressure is doubtless the relative position of the great land- and water-areas; and if this be true of the present, it must be true also of the past. it would almost seem, then, as if all one had to do to ascertain the climatic conditions of any particular period, was to prepare a map depicting with some approach to accuracy the former relative position of land and sea. with such a map could our meteorologists infer what the climatic conditions must have been? yes, provided we could assure them that in other respects the physical conditions did not differ from the present. now there is no period in the past history of our globe the geographical conditions of which are better known than the pleistocene. and yet, when we have indicated these upon a map, we find that they do not give the results which we might have expected. the climatic conditions which they seem to imply are not such as we know did actually obtain. it is obvious, therefore, that some additional and perhaps exceptional factor was at work to produce the recognised results. what was this disturbing element, and have we any evidence of its interference with the operation of the normal agents of climatic change in earlier periods of the world's history? we all know that various answers have been given to such questions. whether amongst these the correct solution of the enigma is to be found, time will show. meanwhile, as all hypothesis and theory must starve without facts to feed on, it behoves us as working geologists to do our best to add to the supply. the success with which other problems have been attacked by geologists forbids us to doubt that ere long we shall have done much to dispel some of the mystery which still envelopes the question of geological climates. ix. the glacial period and the earth-movement hypothesis.[az] [az] this article contains the substance of two papers, one read before the victoria institute, in ; the other an address delivered to the geological society of edinburgh, in . perhaps no portion of the geological record has been more assiduously studied during the last quarter of a century than its closing chapters. we are now in possession of manifold data concerning the interpretation of which there seems to be general agreement. but while that is the case, there remain, nevertheless, certain facts or groups of facts which are variously accounted for. nor have all the phenomena of the pleistocene period received equal attention from those who have recently speculated and generalised on the subject of pleistocene climate and geography. yet, we may be sure, geologists are not likely to arrive at any safe conclusions as to the conditions that obtained in pleistocene times, unless the evidence be candidly considered in all its bearings. no interpretation of that evidence which does not recognise every outstanding group of facts can be expected to endure. it may be possible to frame a plausible theory to account for some particular conspicuous phenomena, but should that theory leave unexplained a residuum of less conspicuous but nevertheless well-proved facts, then, however strongly it may be fortified, it must assuredly fall. as already remarked, there are many phenomena in the interpretation of which geologists are generally agreed. it is, for example, no longer disputed that in pleistocene times vast sheets of ice--continental _mers de glace_--covered broad areas in europe and north america, and that extensive snow-fields and large local glaciers existed in many mountain-regions where snow-fields and glaciers are now unknown, or only meagrely developed. it is quite unnecessary, however, that i should give even the slightest sketch of the aspect presented by the glaciated tracts of our hemisphere at the climax of the ice age. the geographical distribution and extent of the old snow-fields, glaciers, and ice-sheets is matter now of common knowledge. it will be well, however, to understand clearly the nature of the conditions which obtained at the climax of glacial cold--at that stage, namely, when the alpine glaciers reached their greatest development, and when so much of europe was cased in snow and ice. this we shall best do by comparing the present with the past. now in our day the limits of perennial snow are attained at heights that necessarily vary with the latitude. this is shown as follows:-- _region._ _n. lat._ _height of snow-line._ iceland, ° , feet. norway, ° , - , " n. urals, ° ' , " alps, ° , or , " caucasus, ° , - , " apennines, ° ' , " etna, ° ' , " sierra nevada, ° , " thus in traversing europe from north to south the snow-line may be said to rise from feet to , feet in round numbers. it is possible from such data to draw across the map a series of isochional lines, or lines of equal perennial snow, and this has been done by my friend, professor penck of vienna.[ba] it will be understood that each isochional line traverses those regions above which the line of névé is estimated to occur at the same height. thus the isochional line of metres ( feet) runs from the north of norway down to lat. ° on the west coast, whence it must pass west to the south of iceland. the line of metres ( ft.) is traced from the north end of the urals in a westerly direction. it then follows the back-bone of the scandinavian peninsula, passes over to scotland, and thence strikes west along lat. °. for each of these lines good data are obtainable. the line of metres ( ft.) is, however, hypothetical. it is estimated to extend from the ural mountains, about the lat. of °, over the mountains of middle germany and above the north of france. the line of metres ( ft.) passes from the southern termination of the urals, in lat. °, to the east carpathians, thence along the north face of the alps, thereafter south-west across the cevennes to the north-west end of the pyrenees; and thence above the cantabrian and the portuguese highlands to the coast in lat. °. the line of metres ( ft.) is estimated to occur above the caspian sea, near lat. °, and extends west through the north end of the caucasus to the balkans. thence it is traced north-west to the alps, south-west to the pyrenees, which range it follows to the west, and thereafter sweeps south above the coast at cadiz. the line of metres ( , ft.) runs from the caucasus south-west across asia minor to the lebanon mountains; thence it follows the direction of the mediterranean, and traverses morocco above the north face of the atlas range. finally the line of metres ( , feet) is estimated to trend in the same general direction as the last-mentioned line, but, of course, further to the south. although these isochional lines are to some extent conjectural, yet the data upon which they are based are sufficiently numerous and well-known to prevent any great error, and we may admit that the lines represent with tolerable accuracy the general position of the snow-line over our continent. so greatly has our knowledge of the glaciation of europe increased during recent years, that the height of the snow-line of the glacial period has been determined by mm. simony, partsch, penck, and höfer. their method is simple enough. they first ascertain the lowest parts of a glaciated region from which independent glaciers have flowed. this gives the maximum height of the old snow-line. next they determine the lowest point reached by such glaciers. it is obvious that the snow-line would occur higher up than that, but at a lower level than the actual source of the glaciers; and thus the minimum height of the former snow-line is approximately ascertained. the lowest level from which independent glaciers formerly flowed, and the terminal point reached by the highest-lying glaciers having been duly ascertained, it is possible to determine with sufficient accuracy the mean height of the old snow-line. the required data are best obtained, as one might have expected, in the pyrenees and amongst the mountains of middle and southern europe. in those regions the snow-line would seem to have been some feet or so lower than now. from such data professor penck has constructed a map showing the isochional lines of the glacial period. these lines are, i need hardly say, only approximations, but they are sufficiently near the truth to bring out the contrast between the ice age and the present. thus the isochional of metres, which at present lies above northern scandinavia, was pushed south to the latitude of southern france and north italy; while the isochional of metres (now overlying the extreme north of france and north germany) passed in glacial times over the northern part of the mediterranean.[bb] [ba] "geographische wirkungen der eiszeit," _verhandl. d. vierten deutschen geographentages zu münchen_, . [bb] it is interesting to note that while in the tatra (north carpathians) the snow-line was depressed in glacial times to the extent of feet only, in the alps it descended some feet or more below its present level. with the snow-line of that great chain at such an elevation it is obvious that only a few of the higher points of the apennines could rise into the region of _névé_. this is the reason why moraines are met with in only the higher valleys of that range. isochional lines are not isotherms. their height and direction are determined not only by temperature, but by the amount and distribution of the snow-fall. nevertheless, the position of the snow-line in europe during the ice age enables us to form a rough estimate of the temperature. at present in middle europe the temperature falls ° f. for every feet of ascent. hence if we take the average depression of the snow-line in glacial times at feet, that would correspond approximately to a lowering of the temperature by °.[bc] this may not appear to be much, but, as penck points out, were the mean annual temperature to be lowered to that extent it would bring the climate of northern norway down to southern germany, and the climate of sweden to austria and moravia, while that of the alps would be met with over the basin of the mediterranean. [bc] professor brückner thinks the general lowering of temperature may not have exceeded - / ° to ° f. _verhandlungen der jahresversammlung der schweizerischen naturforschenden gesellschaft in davos_, . let it be noted further that this lowering of the temperature--this displacement of climatic zones, was experienced over the whole continent--extending on the one hand south into africa, and on the other east into asia. but while the conditions in northern and central europe were markedly glacial, further south only more or less isolated snow-capped mountains and local glaciers appeared--such, for example, as those of the sierra nevada, the apennines, corsica, the atlas, the lebanon, etc. in connection with these facts we may note also that the azores were reached by floating ice; and i need only refer in a word to the evidence of cold wet conditions as furnished by the plant and animal remains of the pleistocene tufas, alluvia, and peat of southern europe. again in north africa and syria we find, in desiccated regions, widespread fluviatile accumulations, which, in the opinion of a number of competent observers, are indicative of rainy conditions contemporaneous with the glacial period of europe. when we compare the conditions of the ice age with those of the present we are struck with the fact that the former were only an exaggeration of the latter. the development of glaciation was in strict accordance with existing conditions. thus in pleistocene times north america was more extensively glaciated than northern europe, just as to-day greenland shows more snow and ice than scandinavia. no traces of glaciation have been observed as yet in northern asia or in northern alaska, and to-day the only glaciers and ice-sheets that exist in northern regions are confined to the formerly glaciated areas. again, in pleistocene europe glacial phenomena were more strongly developed in the west than in the east. large glaciers, for example, existed in central france, and a considerable ice-flow poured into the basin of the douro. but in the same latitudes of eastern europe we meet with few or no traces of ice-action. again, the vosges appear to have been more severely glaciated than the mountains of middle germany; and so likewise the old glaciers of the western alps were on a much more extensive scale than those towards the east end of the chain. similar contrasts may be noted at the present day. thus we find glaciers in norway under lat. °, while in the ural mountains in the same latitude there is none. the glaciers of the western alps, again, are larger than those in the eastern part of the chain. the caucasus region, it is true, has considerable glaciers, but then the mountains are higher. now turn for a moment to north america. the eastern area was covered by one immense ice-sheet, while in the mountainous region of the west gigantic glaciers existed. in our own day we see a similar contrast. in the north-east lies greenland well-nigh drowned in ice, while the north-west region on the other hand, although considerably higher and occurring in the same latitude, holds only local glaciers. we may further note that at the present day very dry regions, even when these are relatively lofty and in high latitudes, such as the uplands of siberia, contain no glaciers. and the same was the case in the glacial period. these facts are sufficient to show that the conditions of glacial times bore an intimate relation to those that now obtain. could the requisite increase of precipitation and lowering of temperature take place, we cannot doubt that ice-sheets and glaciers would reappear in precisely the same regions where they were formerly so extensively developed. no change in the relative elevation of the land would be required--increased precipitation accompanied by a general lowering of the snow-line for or feet would suffice to reintroduce the ice age. from the foregoing considerations we may conclude:--( ) that the cold of the glacial period was a general phenomenon, due to some widely-acting cause--a cause sufficient to influence contemporaneously the climate of europe and north america; ( ) that glaciation in our continent increased in intensity from east to west, and from south to north; ( ) that where now we have the greatest rainfall, in glacial times the greatest snow-fall took place, and the snow tended most to accumulate; ( ) that in the extreme south of europe, and in north africa and west asia, increased rain precipitation accompanied lowering of temperature, from which it may be inferred that precipitation in glacial times was greater generally than it is now. having considered the climatic conditions that obtained at the climax of the glacial period, i have next to recapitulate what is known as to the climatic changes of pleistocene times. it is generally admitted that the glacial conditions of which i have been speaking were repeated twice, some say three times, during the pleistocene period; while others maintain that even a larger number of glacial episodes may have occurred. two glacial epochs, at all events, have been recognised generally both in europe and north america. these were separated by an interglacial stage of more genial conditions, the evidence for which is steadily increasing. no one now calls in question the existence of interglacial deposits, but, as their occurrence is rather a stumbling-block in the way of certain recently resuscitated hypotheses, some attempt has been made to minimise their importance--to explain them away, in fact. it has been suggested, for example--(and the suggestion is by no means new)--that the deposits in question only show that there were local oscillations during the advance and retreat of the old ice-sheets and glaciers. this, however, is not the view of those who have observed and described interglacial beds--who know the nature of the organic remains which they have yielded, and the conditions under which the beds must have been accumulated. i need not refer to the interglacial deposits of our own country further than to remark that they certainly cannot be explained away in that summary fashion. the peat and freshwater beds that lie between the lower and upper tills in the neighbourhood of edinburgh, for example, are of themselves sufficient to prove a marked and decided change of climate. no mere temporary retreat and re-advance of the ice-sheet will account for their occurrence. the lower till is unquestionably the bottom-moraine of an ice-sheet which, in that region, flowed towards the east. when the geographical position of the deposits in question is considered it becomes clear that an easterly flow of ice in mid-lothian proves beyond gainsaying that during the accumulation of the lower till all scotland was drowned in ice. but when water once more flowed over the land-surface--when a temperate flora, composed of hazels and other plants, again appeared, it is obvious that the ice-sheet had already vanished from central scotland. this is not the case of a mere temporary recession of the ice-front. it is impossible to believe that a temperate or even cold-temperate flora could have flourished in central scotland at a period when thick glacier-ice mantled any portion of our lowlands. again, in the upper till we read the evidence of a recurrence of extreme glacial conditions--when central scotland was once more overwhelmed by confluent ice-streams coming from the highlands and the southern uplands. similar evidence of recurrent glacial conditions, i need hardly remind you, has been detected in other parts of the country. we are justified, then, in maintaining that our interglacial beds point to distinct oscillations of climate--oscillations which imply a long lapse of time. continental observers are equally convinced that the interglacial epoch, of which so many interesting relics have been preserved over a wide region, was marked at its climax by a temperate climate and endured for a long period. the interglacial beds of northern and central europe form everywhere marked horizons in the glacial series. geologists sometimes forget that in every region where glacial accumulations are well developed, good observers had recognised an upper and lower series of "drift-deposits" long before the idea of two separate glacial epochs had presented itself. thus, in north germany, so clearly is the upper differentiated from the lower diluvium that the two series had been noted and mapped as separate accumulations for years before geologists had formulated the theory of successive ice-epochs.[bd] the division of the german diluvium into an upper and a lower series is as firmly established as any other well-marked division in historical geology. the stratigraphical evidence has been much strengthened, however, by the discovery between upper and lower boulder-clays of true interglacial beds, containing lignite, peat, diatomaceous earth, and marine, brackish, and freshwater molluscs, fish, etc., and now and again bones of pleistocene mammals.[be] a similar strongly-marked division characterises the glacial accumulations of sweden, as has been clearly shown by de geer,[bf] who thinks that the older and younger epochs of glaciation were separated by a protracted period of interglacial conditions. in short, evidence of a break in the glacial succession has been traced at intervals across the whole width of the continent, from the borders of the north sea to central russia. m. krischtafowitsch has recently detected in the neighbourhood of moscow[bg] certain fossiliferous interglacial beds, the flora and fauna of which indicate a warmer and moister climate than the present. the interglacial stage, he says, must have been of long duration, and separated in russia as in western europe two distinct epochs of glaciation. [bd] wahnschaffe: _forschungen zur deutschen landes- und volkskunde von dr. a. kirchhoff_, bd. vi., heft . [be] for interglacial beds of north germany see helland: _zeitschr. d. deutsch. geol._ ges., xxxi., ; penck: _ibid._, xxxi., ; _länderkunde von europa_ (das deutsche reich), , ; dames: _samml. gemeinverständl. wissensch. vorträge, von virchow u. holtzendorff:_ xx. ser., heft; schröder: _jahrb. d. k. geol. landensanst. f._ , p. . for further references see wahnschaffe, _op. cit._ i have not thought it worth while in this paper to refer to the interglacial deposits of our own islands. a general account of them will be found in my _great ice age_, and _prehistoric europe_. the interglacial phenomena of the continent seem to be less known here than they ought to be. [bf] _zeitschrift d. deutsch. geolog. gesellschaft_, bd. xxxvii, p. . [bg] _anzeichen einer interglaziären epoche in central-russland_, moskau, . no mere temporary retreat and re-advance of the ice-front can account for these phenomena. the occurrence of remains of the great pachyderms at rixdorf, near berlin, and the character of the flora met with in the interglacial beds of north germany and russia are incompatible with glacial conditions in the low-grounds of northern europe. the interglacial beds, described by dr. c. weber[bh] as occurring near grünenthal, in holstein, are among the more recent discoveries of this kind. these deposits rest upon boulder-clay, and are overlaid by another sheet of the same character, and belong, according to weber, to "that great interglacial period which preceded the last ice-sheet of northern europe." the section shows feet of peat resting on freshwater clay, feet thick, which is underlaid by some feet of "coral sand," with bryozoa. the flora and fauna have a distinctly temperate facies. it is no wonder, then, that continental geologists are generally inclined to admit that north germany and the contiguous countries have been invaded at least twice by the ice-sheets of two separate and distinct glacial epochs. this is not all, however. while every observer acknowledges that the diluvium is properly divided into an upper and a lower series, there are some geologists who have described the occurrence of three, and even more boulder-clays--the one clearly differentiated from the other, and traceable over wide areas. is each of these to be considered the product of an independent ice-sheet, or do they only indicate more or less extensive oscillations of the ice-front? the boulder-clays are parted from each other by thick beds of sand and clay, in some of which fossils have occasionally been detected. it is quite possible that such stratified beds were deposited during a temporary retreat of the ice-front, which when it re-advanced covered them up with its bottom-moraine. on the other hand, the phenomena are equally explicable on the assumption that each boulder-clay represents a separate epoch of glaciation. until the stratified beds have yielded more abundant traces of the life of the period, our judgment as to the conditions implied by them must be suspended. it is worthy of note in this connection, however, that in north america the existence of one prolonged interglacial epoch has been well established, while distinct evidence is forthcoming of what chamberlin discriminates as "stages of deglaciation and re-advancing ice."[bi] [bh] _neues jahrbuch f. mineralogie, geologie, u. palæontologie_, , bd. ii., pp. , ; , bd. i., p. . [bi] _sixth annual report, u. s. geol. survey_, - , p. . when we turn to the alpine lands, we find that there also the occurrence of former interglacial conditions has been recognised. the interglacial deposits, as described by heer and others, are well known. these form as definite a geological horizon as the similar fossiliferous zone in the diluvium of northern germany. the lignites, as heer pointed out, represent a long period of time, and this is still further illustrated by the fact that considerable fluviatile erosion supervened between the close of the first and the advent of the later glacial epoch. no mere temporary retreat and re-advance of the ice will account for the phenomena. let us for a moment consider the conditions under which the accumulations in question were laid down. the glacial deposits underlying the lignite beds contain, amongst other erratics, boulders which have come from the upper valley of the rhine. this means, of course, that the ancient glacier of the rhine succeeded in reaching the lake of zurich; and it is well known that it extended at the same time to lake constance. that glacier, therefore exceeded sixty miles in length. one cannot doubt that the climatic conditions implied by this great extension were excessive, and quite incompatible with the appearance in the low-grounds of switzerland of such a flora as that of the lignites. the organic remains of the lignite beds indicate a climate certainly not less temperate than that which at present characterises the district round the lake of zurich. we may safely infer, therefore, that during interglacial times the glaciers of the alps were not more extensively developed than at present. again, as the lignites are overlaid by glacial deposits, it is obvious that the rhine glacier once more reached lake zurich--in other words, there was a return of the excessive climate that induced the first great advance of that and other swiss glaciers. that these advances were really due to extreme climatic conditions is shown by the fact that it was only under such conditions that the scandinavian flora could have invaded the low-grounds of europe, and entered switzerland. it is impossible, therefore, that the interglacial flora could have flourished in switzerland while the immigration of these northern plants was taking place. lignites of the same age as those of dürnten and utznach occur in many places both on the north and south sides of the alpine chain. at imberg, near sonthofen, in bavaria, for example, they are described by penck[bj] as being underlaid and overlaid by thick glacial accumulations. the deposits in question form a terrace along the flanks of the hills, at a height of feet above the iller. the flora of the lignite has not yet been fully studied, but it is composed chiefly of conifers, which must have grown near where their remains now occur--that is at feet, or thereabout, above the sea. it is incredible that coniferous forests could have flourished at that elevation during a glacial epoch. a lowering of the mean annual temperature by ° c. only would render the growth of trees at that height almost impossible, and certainly would be insufficient to cause the glaciers of algau to descend to the foot of the mountains, as we know they did--a distance of at least twenty-four miles. the imberg lignites, therefore, are evidence of a climate not less temperate than the present. more than this, there is clear proof that the interglacial stage was long continued, for during that epoch the iller had time to effect very considerable erosion. the succession of changes shown by the sections near sonthofen are as follows. . the iller valley is filled with glacier-ice which flows out upon the low-grounds at the base of the alps. . the glacier retreats, and great sheets of shingle and gravel are spread over the valley. . coniferous forests now grow over the surface of the gravels; and as the lignite formed of their remains attains a thickness of ten feet in all, it obviously points to the lapse of some considerable time. . eventually the forests decay, and their débris is buried under new accumulations of shingle and gravel. . the iller cuts its way down through all the deposits to depths of to feet. . a glacier again descends and fills the valley, but does not flow so far as that of the earlier glacial stage. [bj] _die vergletscherung der deutschen alpen_, , p. . in this section, as in those at dürnten and utznach, we have conclusive evidence of two glacial epochs, sharply marked off the one from the other. nor does that evidence stand alone, for at various points between lake geneva and the lower valley of the inn similar interglacial deposits occur. sometimes these appear at the foot of the mountains, as at mörschweil on lake constance; sometimes just within the mountain area, as at imberg; sometimes far in the heart of the alpine lands, as at innsbruck. professor penck has further shown, and his observations have been confirmed by brückner, blaas, and böhm, that massive sheets of fluviatile gravel are frequently met with throughout the valleys of the alps, occupying interglacial positions. these gravels are exactly comparable to the interglacial gravels of the sonthofen sections. and it has been demonstrated that they occur on two horizons, separated the one from the other by characteristic ground-moraine, or boulder-clay. the lower gravels rest on ground-moraine, and the upper gravels are overlaid by sheets of the same kind of glacial detritus. in short, three separate and distinct ground-moraines are recognised. the gravels, one cannot doubt, are simply the torrential and fluviatile deposits laid down before advancing and retreating glaciers; and it is especially to be noted that each sheet of gravel, after its accumulation, was much denuded and cut through by river-action. in a word, as penck and others have shown, the valleys of upper bavaria have been occupied by glaciers at three successive epochs--each separated from the other by a period during which much river-gravel was deposited and great erosion of the valley-bottoms was effected. on the italian side of the alps, similar evidence of climatic changes is forthcoming. the lignites and lacustrine strata of val gandino, and of val borlezza, as i have elsewhere shown,[bk] are clearly of interglacial age. from these deposits many organic remains have been obtained--amongst the animals being _rhinoceros hemitoechus_ and _r. leptorhinus_. according to sordelli, the plants indicate a climate as genial as that of the plains of lombardy and venetia, and warmer therefore than that of the upland valleys in which the interglacial beds occur. professor penck informs me that some time ago he detected evidence in the district of lake garda of three successive glacial epochs--the evidence being of the same character as that recognised in the valleys of the bavarian alps. [bk] _prehistoric europe_, p. . in the glaciated districts of france similar phenomena are met with. thus in cantal, according to m. rames,[bl] the glacial deposits belong to two separate epochs. the older morainic accumulations are scattered over the surface of the plateau of archæan schistose rocks, and extend up the slopes of the great volcanic cone of that region to heights of to feet. one of the features of these accumulations are the innumerable gigantic erratics, known to the country folk as _cimetière des enragés_. sheets of fluvio-glacial gravel are also associated with the moraines, and it is worthy of note that both have the aspect of considerable age--they have evidently been subjected to much denudation. in the valleys of the same region occurs a younger series of glacial deposits, consisting of conspicuous lateral and terminal moraines, which, unlike the older accumulations, have a very fresh and well-preserved appearance. with them, as with the older moraines, fluvio-glacial gravels are associated. m. rames shows that the interval that supervened between the formation of the two series of glacial deposits must have been prolonged, for the valleys during that interval were in some places eroded to a depth of feet. not only was the volcanic _massif_ deeply incised, but even the old plateau of crystalline rocks on which the volcanic cone reposes suffered extensive denudation in interglacial times. m. rames further recognises that the second glacial epoch was marked by two advances of the valley-glaciers, separated by a marked episode of fusion, the evidence for which is conspicuous in the valley of the cère. [bl] _bull. soc. géol. de france_, . the glacial and interglacial phenomena of auvergne are quite analogous to those of cantal. dr. julien has described the morainic accumulations of a large glacier that flowed from mont dore. after that glacier had retreated a prolonged period of erosion followed, when the morainic deposits were deeply trenched, and the underlying rocks cut into. in the valleys and hollows thus excavated freshwater beds occur, containing the relics of an abundant flora, together with the remains of elephant (_e. meridionalis_), rhinoceros (_r. leptorhinus_), hippopotamus, horse, cave-bear, hyæna, etc.--a fauna comparable to that of the italian interglacial deposits. after the deposition of the freshwater beds, glaciers again descended the auvergne valleys and covered the beds in question with their moraines.[bm] [bm] _des phénomènes glaciaires dans le plateau central de france, etc._ according to the researches of martins, collomb, garrigou, piette, and penck, there is clear evidence in the pyrenees of two periods of glaciation, separated by an interval of much erosion and valley-excavation. penck, indeed, has shown that the valleys of the pyrenees have been occupied at three successive epochs by glaciers--each epoch being represented by its series of moraines and by terraces of fluvio-glacial detritus, which occur at successively lower levels. i have referred in some detail to these discoveries of interglacial phenomena because they so strongly corroborate the conclusions arrived at a number of years ago by glacialists in our own country. many additional examples might be cited from other parts of europe, but those already given may serve to show that at least one epoch of interglacial conditions supervened during the pleistocene period. before leaving this part of my subject, however, i may point out the significant circumstance that long before much was known of glaciation, and certainly before the periodicity of ice-epochs had been recognised, collomb had detected in the vosges conspicuous evidence of two successive glaciations.[bn] [bn] _preuves de l'existence d'anciens glaciers dans les vallées des vosges_, , p. . having shown that alike in the regions formerly occupied by the great northern ice-sheet, and in the alpine lands of central and southern europe, alternations of cold and genial conditions characterised the so-called glacial period, we may now glance at the evidence supplied by those pleistocene deposits that lie outside of the glaciated areas. of these we have a typical example in the river-accumulations of the rhine valley between bâle and bingen. here and there these deposits have yielded remains of extinct and no longer indigenous mammals and relics of palæolithic man--one of the most interesting deposits from which mammalian remains have been obtained being the sands of mosbach, between wiesbaden and mayence. the fauna in question is characteristically pleistocene, nor can it be doubted that the mosbach sands belong to the same geological horizon as the similar fluviatile deposits of the seine, the thames, and other river-valleys in western europe. dr. kinkelin has shown,[bo] and with him dr. schumacher agrees,[bp] that the mosbach deposits are of interglacial age; while dr. pohlig has no hesitation in assigning them to the same horizon.[bq] it is true there are no glacial accumulations in the region where they occur, but they rest upon a series of unfossiliferous gravels which are recognised as the equivalents of the fluvio-glacial and glacial deposits of the vosges, the black forest, the alps, etc. these gravels are traced at intervals up to considerable heights above the rhine, and contain numerous erratics, some of which are several feet in diameter, while a large proportion are not at all water-worn, but roughly and sharply angular. the blocks have unquestionably been transported by river-ice, and imply therefore cold climatic conditions. the overlying mosbach sands have yielded not only _elephas antiquus_ and _hippopotamus major_, but the reindeer, the mammoth, and the marmot--two strongly contrasted faunas, betokening climatic changes similar to those that marked the accumulation of the river-deposits of the thames, the seine, etc. of younger date than the mosbach sands is another series of unfossiliferous gravels, which, like the older series, are charged with ice-floated erratics. the beds at mosbach are thus shown to be of interglacial age: they occupy the same geological horizon as the interglacial beds of switzerland and other glaciated tracts in central and northern europe. [bo] kinkelin: _bericht über die senckenberg. naturf. ges. in frankfurt a. m._, . [bp] schumacher: _mittheilungen d. commission für d. geolog. landes-untersuch. v. elsass-lothringen_, bd. ii., , p. . [bq] _zeitschr. d. deutsch. geolog. ges._, , p. . to this position must likewise be assigned the pleistocene river-alluvia of other districts. there is no other horizon, indeed, on which these can be placed. that they are not of post-glacial age is shown by the fact that in many places the angular gravels and flood-loams of the glacial period overlie them. and that they cannot all belong to pre-glacial times is proved by the frequent occurrence underneath them of glacial or fluvio-glacial accumulations. it is quite possible, of course, that here and there in the valleys of western and southern europe some of the pleistocene alluvia may be of pre-glacial age. but in the main these alluvia must be regarded as the equivalents of the glacial and interglacial deposits of northern and alpine districts. this will appear a reasonable conclusion when we bear in mind that long before the pliocene period came to a close the climate of europe had begun to deteriorate. in england, as we know, glacial conditions supervened almost at the advent of the pleistocene period. and the same was the case in the alpine lands of the south. again, in the glaciated areas of north and south alike, the closing stage of the pleistocene was characterised by cold climatic conditions. and thus in those regions the glacial and interglacial epochs were co-extensive with that period. it follows, therefore, that the pleistocene deposits of extra-glacial areas must be the equivalents of the glacial and interglacial accumulations elsewhere. if we refused to admit this we should be puzzled indeed to tell what the rivers of western and southern europe were doing throughout the long-continued glacial period. there is no escape from the conclusion that the pleistocene river-alluvia and cave-accumulations must be assigned to the same general horizon as the glacial and interglacial deposits. this is now admitted by continental palæontologists who find in the character of pleistocene organic remains abundant proof that the old river-alluvia and cave-accumulations were laid down under changing climatic conditions. did neither glacial nor interglacial deposits exist, the relics of the pleistocene flora and fauna met with in extra-glacial regions would yet lead us to the conclusion that after the close of the pliocene period, extremely cold and very genial climates alternated up to the dawn of the present. thus during one stage of the pleistocene "clement winters and cool summers permitted the wide diffusion and intimate association of plants which have now a very different range. temperate and southern species like the ash, the poplar, the sycamore, the fig-tree, the judas-tree, etc., overspread all the low-grounds of france as far north at least as paris. it was under such conditions that the elephants, rhinoceroses, hippopotamuses, and the vast herds of temperate cervine and bovine species ranged over europe, from the shores of the mediterranean up to the latitude of yorkshire, and probably even further north still, and from the borders of asia to the western ocean. despite the presence of numerous fierce carnivora--lions, hyænas, tigers, and others--europe at that time, with its shady forests, its laurel-margined streams, its broad and deep-flowing rivers--a country in every way suited to the needs of a race of hunters and fishers--must have been no unpleasant habitation for palæolithic man." but during another stage of the pleistocene period, the climate of our continent presented the strongest contrast to those genial conditions. at that time "the dwarf birch of the scottish highlands, and the arctic willow, with their northern congeners, grew upon the low-grounds of middle europe. arctic animals, such as the musk-sheep and the reindeer, lived then, all the year round, in the south of france; the mammoth ranged into spain and italy; the glutton descended to the shores of the mediterranean; the marmot came down to the low-grounds at the foot of the apennines; and the lagomys inhabitated the low-lying maritime districts of corsica and sardinia. the land and freshwater molluscs of many pleistocene deposits tell a similar tale: high alpine, boreal, and hyperborean forms are characteristic of those deposits in central europe; even in the southern regions of our continent the shells testify to a former colder and wetter climate. it was during the climax of these conditions that the caves of aquitaine were occupied by those artistic men who appear to have delighted in carving and engraving."[br] such, in brief, is the testimony of the pleistocene flora and fauna of extra-glacial regions. it is from the deposits in these regions, therefore, that we derive our fullest knowledge of the life of the period. but a comparison of their organic remains with those that occur in the glacial and interglacial deposits of alpine and northern lands shows us that the pleistocene accumulations of glacial and extra-glacial countries are contemporaneous--for there is not a single life-form obtained from interglacial beds which does not also occur in the deposits of extra-glacial regions. the converse is not true--nor is that to be wondered at, for interglacial deposits have only been sparingly preserved. in regions liable to glaciation such superficial accumulations must frequently have been ploughed up and incorporated with ground-moraine. it was only in the extra-glacial tracts that alluvia of interglacial age were at all likely to be preserved in any abundance. to appreciate fully the climatic conditions of the pleistocene period, therefore, it is necessary to combine the evidence derived from the glaciated areas with that obtained from the lands that lay beyond the reach of the ice-plough. the one is the complement of the other, and this being so, it is obvious that any attempted explanation of the origin of the glacial period which does not fully realise the importance of the interglacial phase of that period cannot be accepted. [br] _prehistoric europe_, p. . but if the climatic changes of pleistocene times are the most important phenomena which the geologist who essays to trace the history of that period is called upon to consider, he cannot ignore the evidence of contemporaneous geographical mutations. these are so generally admitted, however, that it is only necessary here to state the well-known fact that everywhere throughout the maritime tracts of the glaciated lands of europe and north america frequent changes in the relative level of land and sea took place during pleistocene and post-glacial times. i must now very briefly review the evidence bearing on the climatic conditions of post-glacial times. and first, let it be noted that the closing stage of the pleistocene period was one of cold conditions, accompanied in north-western europe by partial depression of the land below its present level. this is shown by the late-glacial marine deposits of central scotland and the coast-lands of scandinavia. the historical records of the succeeding post-glacial period are furnished chiefly by raised beaches, river- and lake-alluvia, calcareous tufas, and peat-bogs. an examination of these has shown that the climate, at first cold, gradually became less ungenial, so that the arctic-alpine flora and northern fauna were eventually supplanted in our latitude by those temperate forms which, as a group, still occupy this region. the amelioration of the climate was accompanied by striking geographical changes, the british islands becoming united with themselves and the opposite coasts of the continent. the genial character of the climate at this time is shown by the great development of forests, the remains of which occur under our oldest peat-bogs. not only did trees then grow at greater altitudes in these regions than is at present the case, but forests ranged much further north, and flourished in lands where they cannot now exist. in orkney and shetland, in the far north of norway, and even in the faröe islands and in iceland relics of this old forest-epoch are met with. in connection with these facts reference may be made to the evidence obtained from certain raised beaches on both sides of the n. atlantic, and from recent dredgings in the intervening sea. the occurrence of isolated colonies of southern molluscs in our northern seas, and the appearance in raised beaches of many forms which are now confined to the waters of more southern latitudes, seem to show that in early post-glacial times the seas of these northern latitudes were warmer than now. and it is quite certain that the southern forms referred to are not the relics of any pre-glacial or interglacial immigration. they could only have entered our northern seas after the close of the glacial period, and their evidence taken in connection with that furnished by the buried trees of our peat-bogs, leads to the conclusion that a genial climate supervened after the cold of the last glacial epoch and of earliest post-glacial times had passed away. to this genial stage succeeded an epoch of cold humid conditions, accompanied by geographical changes which resulted in the insulation of britain and ireland--the sea encroaching to some extent on what are now our maritime regions. the climate was less favourable to the growth of forests, which began to decay and to become buried under widespread accumulations of growing peat. at this time glaciers reappeared in the glens of the scottish highlands, and here and there descended to the sea. the evidence for these is quite conspicuous, for the moraines are found resting on the surface of post-glacial beaches. thus my friend mr. l. hinxman, of the geological survey, tells us that at the foot of glen thraill well-formed moraines are seen in section reposing on beach-deposits at the distance of about three-quarters of a mile above the head of loch torridon.[bs] the evidence of this recrudescence of glacial conditions in post-glacial times is not confined to scotland. i believe it will yet be recognised in many other mountain-regions; but already prof. penck has detected it in the valleys of the pyrenees.[bt] dr. kerner von marilaun has also described similar phenomena in the higher valleys of tyrol, while professor brückner has obtained like evidence in the salzach region.[bu] [bs] for scottish post-glacial glaciers see j. geikie: _scottish naturalist_, jan., ; _prehistoric europe_, pp. , ; penck: _deutsche geographische blätter_, bd. vi., p. ; _verhand. d. ges. f. erdkunde, berlin_, , heft ; hinxman: _trans. edin. geol. soc._, vol. vi., p. . [bt] "die eiszeit in den pyrenäen": _mitth. d. vereins. f. erdkunde_, leipzig, . [bu] kerner: _mitth. k. k. geograph. ges. wien_, , p. ; _sitzungsb. d. kais. akad. d. wissensch. in wien_, bd. c., abth. i., ; brückner: _x. jahresbericht d. geograph. ges. v. bern_, . i have elsewhere traced the history of the succeeding stages of the post-glacial period, and brought forward evidence of similar but less strongly-marked climatic changes having followed upon those just referred to, and my conclusions, i may add, have been supported by the independent researches of professor blytt in norway. but these later changes need not be considered here, and i shall leave them out of account in the discussion that follows. it is sufficient for my present purpose to confine attention to the well-proved conclusion that in early post-glacial times genial climatic conditions obtained, and that these were followed by cold and humid conditions, during the prevalence of which considerable local glaciers reappeared in certain mountain-valleys.[bv] [bv] for a full statement of the evidence see _prehistoric europe_, chaps. xvi., xvii. we speak of pleistocene or glacial and of post-glacial periods as if the one were more or less sharply marked off from the other. of course, that is not the case, and in point of fact it would be for many reasons preferable to include them under some general term. taken together they form one tolerably well-defined cycle of time, characterised above all by its remarkable climatic changes--by alternations of cold and genial conditions, which were most strongly contrasted in the earlier stages of the period. it is further worthy of note that various oscillations of the sea-level appear to have taken place again and again both in the earlier and later stages of the cycle. we may now proceed to inquire whether the phenomena we have been considering can be accounted for by movements of the earth's crust--a view which has recently received considerable support, more especially in america. i need hardly say that the view in question is no novelty. many years ago, while our knowledge of the pleistocene phenomena was somewhat rudimentary, it was usual to infer that glaciation had been induced by elevation of the land. this did not seem an unreasonable conclusion, for above our heads, at a less or greater elevation, according to latitude, an arctic climate prevails. one could not doubt, therefore, that if a land-surface were only sufficiently uplifted it would reach the snow-line, and become more or less extensively glaciated. but with the increase of our knowledge of pleistocene and post-glacial conditions, such a ready interpretation failed to satisfy, although not a few geologists have continued to defend the "earth-movement hypothesis," as accounting fairly well for the phenomena of the glacial period. by these staunch believers in the adequacy of that view, it has been pointed out that elevation might not only lift lands into the region of eternal snow, but, by converting large areas of the sea-bed into land, would greatly modify the direction of ocean-currents, and thus influence the climate. what might not be expected to happen were the gulf stream to be excluded from northern regions? what would be the fate of the temperate latitudes of north america and europe were that genial ocean-river to be deflected into the pacific across a submerged isthmus of panama? the possibility of such changes having supervened in pleistocene times has often been present to my mind, but i long ago came to the conclusion that they could not account for the facts. moreover, i have never been able to meet with any evidence in favour of the postulated "earth-movements." having carefully studied all that has been advanced of late years in support of the hypothesis in question i find myself more than ever constrained to oppose it, not only because it is grounded on no basis of fact, but because it altogether fails to explain the conditions that obtained in pleistocene and post-glacial times. there are various forms in which the hypothesis has appeared, and these i shall now consider seriatim, and with such brevity as may be. it has been maintained, for example, that at the advent of the glacial period vast areas of northern and north-western europe, together with enormous regions in the corresponding latitudes of north america, stood several thousand feet higher than at present. but when we ask what evidence can be adduced to prove this we get no satisfactory reply. we are simply informed that a glacial climate must have resulted from great elevation, and that the latter, therefore, must have taken place at the beginning of the glacial period. some writers, however, have ventured to give reasons for their faith. thus mr. w. upham, pointing to the evidence of the fiords of north america, and to the fact that drowned river-valleys have been traced outwards across the -fathoms line of the marginal plateau to depths of over feet, maintains that the whole continent north of the gulf of mexico stood at the commencement of the glacial period some feet at least higher than now. of course he cites the fiords of europe as evidence of a similar great upheaval for the northern and north-western regions of our continent. mr. upham even favours the notion that during glacial times a land-connection probably existed between north america and europe, by way of the british islands, iceland, and greenland. when "this uplifting attained its maximum, and brought on the glacial period," he says, "north america and north-western europe stood to feet above their present height."[bw] [bw] _american geologist_, vi., p. . that fiords are simply submerged land-valleys has long been recognised: that they have been formed mainly by the action of running water--just in the same way as the mountain-valleys of norway and scotland--has been the belief for many years of most students of physical geology. but it is hard to understand why they should have been cited by mr. upham in support of his contention, seeing that their evidence seems to militate strongly against the very hypothesis he strives to maintain. no one acquainted with the physical features and geological structure of scotland and norway can doubt that the valleys which terminate in fiords are of great geological antiquity. their excavation by fluviatile action certainly dates back to a period long anterior to the advent of the ice age. and a like tale is told by the fiords and drowned valley-troughs of north america, which cannot be referred to so recent a period as post-tertiary times. those who are convinced that our continental areas have persisted throughout long æons of geological time, and that rivers frequently have survived great geological revolutions--cutting their way across mountain-elevations as fast as these were uplifted--will readily believe that some of the submarine river-troughs of north america, such as that of the hudson, may belong even to secondary times.[bx] it would be hard to say at what particular date the excavation of the scottish highland valleys commenced--but it was probably during the later part of the palæozoic era. the process has doubtless been retarded and accelerated frequently enough, during successive movements of depression and elevation, but it was practically completed before the beginning of pleistocene times, and that is all that we may trouble about here. precisely the same conclusion holds good for norway: and such being the case it is obvious that the question of the origin and age of the fiords has no bearing on the problem of the glacial climate and its cause. in point of fact the evidence, as already remarked, tells against the "earth-movement hypothesis," for it shows us that, during a period when europe and north america stood several thousand feet higher, and extended much further seawards, rivers, and not glaciers, were the occupants of our mountain-valleys. it was not until all those valleys had come to assume much the appearance they now present that general glaciation supervened. [bx] professor dana inclines to date the erosion of the hudson trough so far back as the jura-trias period.--_american journ. science_, xl., p. . we are not without direct evidence, however, as to the geographical conditions that obtained in the ages that immediately preceded the pleistocene period. the distribution of the pliocene marine beds of britain entitles us to assume that at the time of their accumulation our lands did not extend quite so far to the south and east as now. the absence of similar deposits from the coast-lands of north america is supposed to support the view of great continental elevation in pre-glacial times. all it seems to prove, however, is that in pliocene times the north american continent was not less extensive than it is at present. it is even quite possible that in glacial times pre-existing pliocene beds may have been ploughed out by the ice, just as seems to have been the case in the north-east of scotland. but without going so far back as pliocene times, we meet with evidence almost everywhere throughout the maritime regions of the glaciated areas of europe and north america, to show that immediately before those tracts became swathed in ice the geographical conditions were much the same as at present. the shelly boulder-clays in various parts of our islands, and the similar occurrence of marine and brackish-water shells in and underneath the diluvium of north germany, etc., prove clearly enough that just before the coming-on of glacial conditions neither britain nor the present maritime lands of the continent were far removed from the sea. it is true that the buried river-channels of scotland indicate a pre-glacial elevation of some or feet above the existing sea-level, but it is quite certain that the minch, st. george's channel, the irish sea, the north sea, and the baltic were all in existence at the commencement of the glacial period. and we are led to similar conclusions with regard to the geographical conditions of north america at that time, from the occurrence of marine shells in the boulder-clays of canada and new england. we note indeed that there is abundant evidence of land-submergence during glacial times. indeed, we may say that the pleistocene marine deposits of northern latitudes are almost invariably indicative of colder conditions than now obtain. if it be true that cold climatic conditions were contemporaneous in our latitude with submergence, it is equally true that an extensive land-surface in north-west europe has, sometimes at least, co-existed with markedly genial conditions. in tertiary times, for example, as the oligocene deposits of scotland, the faröe islands, iceland, and greenland testify, a land-connection existed between europe and the north american continent. again, it has been shown that during the interglacial phase of the pleistocene period britain was continental, and enjoyed at the time a peculiarly genial climate. and somewhat similar geographical and climatic conditions again supervened in post-glacial times. in other words, when the land was more elevated and extensive than now, it enjoyed a warmer climate. nor can we escape the conclusion that the excavation of the fiord-valleys of northern latitudes, which is a very old story (far older than the pleistocene), was the work not of glaciers but of running water, at a time when north-western europe and the corresponding regions of america were much more elevated than they are now. thus there appears to be no evidence either direct or indirect in favour of the view that glacial conditions were superinduced by great continental elevation. but it may be argued that even although no evidence can be cited in proof of such elevation, still, if the glacial phenomena can be well explained by its means, we may be justified in admitting it as a working hypothesis. movements of elevation and depression have frequently taken place--the pleistocene marine deposits themselves testify to oscillations of the sea-level--and there can be no objection, therefore, to such postulations as are made by the hypothesis under review. all this is readily granted, but i deny that the conditions that obtained in pleistocene times can be accounted for by elevation and depression. let us see how the desiderated elevation of northern lands would work. were north-western europe and the corresponding latitudes of north america to be upheaved for feet, and a land-passage to obtain between the two continents by way of the faröe islands, iceland, and greenland, how would the climate be affected? it is obvious that under such changed conditions the elevated lands in higher latitudes might well be subjected to more or less extensive glaciation. norway would become uninhabitable and glaciers might well appear in the mountain-valleys of scotland. but it may be doubted whether the climate of france and spain, or the corresponding latitudes of north america, would be much affected. for were a land-passage to appear between britain and greenland no arctic current would flow into the north atlantic, while no portion of the gulf stream would be lost in arctic seas. the north atlantic would then form a great gulf round which a warm ocean-current would circulate. the temperature of that sea, therefore, would be raised and the prevailing westerly and south-westerly winds of europe would be warmer than now. however much such warm moist winds might increase the snow-fall in north britain and scandinavia, we cannot suppose they could have much influence in central and southern europe, and in north africa; and still less could they affect the climate of asia minor and the mountainous regions of the far east, in most of which evidence of extensive glaciation occurs. and how, we may ask, could the postulated geographical changes bring about the glaciation of the mountainous tracts on the pacific sea-board? in fine, we may conclude that however much the geographical changes referred to might affect north-western europe and north-eastern america, they are wholly insufficient to account for the glacial phenomena of other regions. the continuous research of recent years has shown that the lowering of temperature of glacial times was not limited to the lands which would be affected by any such elevation as that we are considering. a marked and general displacement of climatic zones took place over the whole continent of europe; and similar changes supervened in north america and asia. are we then to suppose that all the lands within the northern hemisphere were extensively and contemporaneously upheaved? we may now consider another form of the "earth-movement hypothesis." it has frequently been suggested that our glacial phenomena may have been caused by the submergence of the isthmus of panama, and the deflection of the equatorial current into the pacific. but it may be doubted whether a submergence of that isthmus, unless very extensive indeed, would result in more than a partial escape of atlantic water into the pacific basin. the counter current of the pacific which now strikes against the isthmus might even sweep into the caribbean sea, and join the equatorial on its way to the gulf of mexico. but putting that consideration aside, what evidence have we that the isthmus of panama was submerged during the glacial epoch? none whatsoever, it may be replied. it is only a pious opinion. considerable movements of elevation and depression of the islands in the caribbean sea would seem to have taken place at a comparatively recent date, but those movements may quite well belong to pliocene times. whether they be of pliocene or pleistocene age, however, no one has yet proved that the isthmus of panama was sufficiently submerged, either at the one time or the other, to permit the escape of the atlantic equatorial into the pacific basin. but let it be supposed that the isthmus has become so deeply submerged that the equatorial current is wholly deflected, and that no gulf stream issues through the straits of florida to temper the climate of higher latitudes. what would result from such an unhappy change? can any one conversant with the geographical distribution of the glacial phenomena imagine that the conditions of the glacial period could be thus reproduced? norway might indeed become a second south greenland, and perennial snow and ice might appear in the mountainous tracts of the british islands. the climate of hudson's bay and the surrounding lands might be experienced in the baltic and its neighbourhood, and what are now the temperate latitudes of europe, north of the th parallel, would possibly approach siberia in character. but surely these changes are not comparable to the conditions of the glacial period. the absence of a gulf stream would not sensibly affect the climate of south-eastern europe and asia, and could not have the smallest influence on that of the pacific coast-lands of north america. yes, but if we conceive the submergence of the isthmus of panama to coincide with great elevation of northern lands, would not such geographical conditions bring about a glacial epoch comparable to that of pleistocene times? it is hard to see how they could. no doubt the climate of all those regions that would be affected by the withdrawal of the gulf stream alone would become still more deteriorated if they stood some feet higher than now. a vast area in the north-west of europe would certainly be uninhabitable, but it is for the advocates of the "earth-movement hypothesis" to explain why those inhospitable regions should necessarily be covered with an ice-sheet. for the production of great snow-fields and continental ice-sheets, considerable precipitation, no less than a low temperature, is requisite. under the conditions we have been imagining, however, precipitation would probably be much less than it is at present. but to whatever extent north-west europe might be glaciated, it is obvious that the geographical revolutions referred to could have little influence on the climate of south-eastern europe, not to mention central and eastern asia. nor could they possibly influence the climate of the pacific coast-lands of north america. and yet, as is well known, the climate of all those regions was more or less profoundly affected during the glacial period. to account for the widespread evidences of glaciation by means of elevation it would therefore seem necessary to infer that all the affected areas were in pleistocene times uplifted _en masse_ into the arctic zone that stretches above our heads. now it seems easier to believe that the snow-line was lowered by several thousand feet than that the continents were elevated to the same extent. glaciation, as we have seen, was developed in the same directions and over the same areas as we should expect it to be were the snow-line to be generally depressed. to put it in another way, were the snow-line by some means or other to be lowered over europe, asia, and north america, then, with sufficient precipitation, great ice-fields and glaciers would reappear in the very regions which they visited during pleistocene times. neither elevation nor depression of the land would be required to bring about such a result. certain advocates of the "earth-movement hypothesis," however, do not maintain that all the glaciated areas were uplifted at one and the same time. the glaciation of the alps, they think, may have taken place earlier or later than that of north-western europe, while the ice-period of the rocky mountains may not have coincided with that of eastern north america. it is not impossible, they suppose, that the glaciation of the himalayas may have been caused by an uplifting of that great chain, quite independent of similar earth-movements in other places. it can be demonstrated, however, that the glaciation of the alps and of northern europe were contemporaneous, and the facts go far to prove that the glaciers of the rocky mountains and the inland-ice of north-east america likewise co-existed. at all events all the old glacial accumulations of our hemisphere are of pleistocene age, and it is for the advocates of the hypothesis under review to prove that they are not contemporaneous. their doubts on the subject probably arise from the simple fact that they are well aware how highly improbable or even impossible it is that all those glaciated lands could have been pushed up within the snow-line at one and the same time. let me, however, advance to another objection. we know that the glacial period was interrupted by at least one interglacial epoch of temperate and even genial conditions. two glacial epochs with one protracted interglacial epoch are now generally admitted. how do the supporters of the "earth-movement hypothesis" explain this remarkable succession of climatic changes? their views as to the cause of glacial conditions we have considered. if we can believe that the glacial phenomena were due to elevation of the land, then we need have no difficulty in understanding how glacial conditions would disappear when the continents again subsided to a lower level. not only did north america and europe lose all their early glacial elevation, but by a lucky coincidence the isthmus of panama reappeared, and the gulf stream resumed its beneficent course into the north atlantic. this we are to suppose was the cause of the interglacial epoch. but i would point out that the geographical conditions which are thus inferred to have brought about the disappearance of the glacial climate, and to have ushered in the interglacial epoch, are precisely those that now obtain--and, nevertheless, we are not yet in the enjoyment of a climate like that of interglacial times. the strangely equable conditions that permitted the development of the remarkable pleistocene flora and fauna are not experienced in the europe of our day. and what about the second glacial epoch? are we to suppose that once more the lands were greatly uplifted, and that convenient isthmus of panama was again depressed? did the alps, the pyrenees, and the plateau of central france--in all of which we have distinct evidence of at least two glacial epochs--did these heights, one may ask, rise up to bring about their earlier glaciation, sink down again to induce interglacial conditions, and once more become uplifted at the succeeding cold epoch, to subside eventually in order to cause a final retreat of their glaciers? but the climatic changes to be accounted for were in all probability more numerous and complex than those just referred to. competent observers have adduced unmistakable evidence of three epochs of glaciation in the alpine lands of europe. and we are not without distinct hints that similar changes have taken place in northern and western europe. nor in this connection can we ignore the evidence of several interglacial episodes which mr. chamberlin and others have detected in the glaciated tracts of north america. even this is not all, for the upholders of the "earth-movement hypothesis" have still further to account for the climatic oscillations of post-glacial times. if it be hard enough to allow the possibility of one great movement of elevation having affected so enormous an area of our hemisphere, if we find it extremely difficult to believe either that one such widespread movement, or that a multitude of local movements, each more or less independent of the other, could have lifted the glaciated regions successively within reach of the snow-line--we shall yet find it impossible to admit that such remarkable upheavals could be repeated again and again. we seem driven to conclude, therefore, that the "earth-movement hypothesis" fails to explain the phenomena of pleistocene times. one cannot deny, indeed, that glaciation might be induced locally by elevation of the land. it is quite conceivable that mountains now below the limits of perennial snow might come to be ridged up to such an extent as to be capable of sustaining snow-fields and glaciers. and such local movements may possibly have happened here and there during the long-continued pleistocene period. but the glacial phenomena of that period are on much too grand a scale and far too widely distributed to be accounted for in that way. and if the occurrence of even one glacial epoch cannot be thus explained, we may leave the supporters of the "earth-movement hypothesis" to show us what light is thrown by their urim and thummim on the origin of succeeding interglacial and glacial climates. there is yet another physical condition of the pleistocene and post-glacial periods which any adequate explanation must embrace. i refer to the oscillation of sea-level, of which so many proofs are forthcoming. it is very remarkable that almost everywhere throughout the maritime regions of formerly glaciated areas we find evidence of submergence. so commonly is this the case, that geologists have long suspected that the connection between glaciation and submergence might be one of cause and effect. the possible influence of great ice-sheets in disturbing the relative level of land and sea is a question, therefore, of very great importance. it is one, however, which must be solved by physicists. croll and others have advocated the view that the great accumulations of ice of the glacial period may have displaced the earth's centre of gravity, and thus caused the sea to rise upon the glaciated hemisphere. the various results arrived at by physicists are hardly comparable, because each has used different data, but it seems probable that we have in this view a _vera causa_ of oscillations of the sea-level. another hypothesis would explain the rise of the sea as due to the attractive influence of the great ice-masses, but dr. drygalski's and mr. woodward's elaborate investigations would seem to have demonstrated that this notion does not account for the facts. yet another speculation has been advanced. mr. jamieson has suggested that the mere weight of the ice-sheets would suffice to press down the earth's crust into a supposed liquid substratum, and this explanation has met with much acceptance. unfortunately our knowledge of the condition of the earth's interior is so very limited that we cannot be certain as to how the crust would be affected by the weight of an ice-sheet. no doubt mr. jamieson's hypothesis gives a specious explanation of certain geological phenomena, but if there be no liquid substratum underlying a thin crust it cannot be true. at present the prevalent view of physicists appears to be that the earth is substantially solid. professor george darwin has shown that the prominent inequalities of the earth's surface could not be sustained unless the crust be as rigid as granite for a depth of miles. "if the earth be solid throughout," he remarks, "then at miles from the surface the material must be as strong as granite. if it be fluid or gaseous inside, and the crust miles thick, that crust must be stronger than granite, and if only or miles in thickness, much stronger than granite." this conclusion is obviously strongly confirmatory of sir william thomson's view, that the earth is solid throughout. but many geologists find it hard to account for the convolutions of strata and other structural phenomena on the supposition that the earth is entirely solid, and they are inclined, therefore, to adopt the hypothesis of a sub-crust layer of liquid matter. whether this be actually the condition or not physicists must be left to determine. all that we need note is, that if there be any force in professor darwin's argument, it is obvious that the crust is possessed of great rigidity, and could not be readily deformed by the mere weight of an ice-sheet. according to dr. drygalski, however, the presence of an ice-sheet, by reducing the temperature of the underlying crust, would bring about contraction, and in this way cause the surface to sink. when the ice-sheet had disappeared, then free radiation of earth-heat would be resumed, the depressed isogeotherms would rise, and a general warming of the upper portion of the lithosphere would take place. but the space occupied by the depressed section, owing to the spheroidal form of the earth, would be smaller than that which it occupied before sinking had commenced, and consequently when the ice vanished expansion of the crust would follow, and the land-surface would then rise again. the whole question is one for physicists to decide upon, but i may point out that if drygalski's explanation be well founded, then it is obvious that it throws no light upon the origin and subsequent disappearance of an ice-sheet. somehow or other this ice-sheet comes into existence, and the cooling and contracting crust sinks below it; and that depressed condition of the glaciated area must continue so long as the ice-sheet remains unmelted. re-elevation can only take place when, owing to some other cause or causes, the climate changes and the ice-sheet vanishes. those who advocate the "earth-movement hypothesis" as an explanation of the origin of extensive glaciation have welcomed mr. jamieson's view as harmonising well with their conclusions. they contend, as we have seen, that glacial conditions were induced by an extensive upheaval of the crust in northern latitudes, accompanied by a depression of the isthmus of panama. they then proceed to point out that the ice-sheets brought about their own dissolution by pressing down the crust, and introducing with submergence a disappearance of glacial conditions. see now how much they take for granted. in the first place, they assume an amount of pre-glacial or early glacial elevation of northern regions for which not a scrap of evidence can be adduced, while they can give no proof of contemporaneous depression of the isthmus of panama. next, relying on mr. jamieson's hypothesis, they take for granted that the ice-sheets, called into existence by their postulated earth-movements, succeeded in depressing the earth's surface even below its present level. that is to say, the land, which, according to them, was in glacial times some feet higher than now, sank down under the weight of its glacial covering for, say, feet in north-western europe. in north america, in like manner, all the pre-glacial elevation was lost--the land sinking below its present level for some feet in new england, for feet at montreal, for to feet in labrador, and for to feet in the arctic regions. now, even if we concede the reasonableness of mr. jamieson's hypothesis, and admit that a certain degree of deformation may take place under the mere weight of an ice-sheet, it is difficult to believe that the crust can be so readily deformed as the supporters of the "earth-movement hypothesis" seem to imply. if it could yield so readily to pressure, one is at a loss to understand how a great ice-sheet could accumulate--the ice would simply float off as the land subsided. take the case of north-western europe. the ice-sheet that covered scotland did not attain, on the average, feet in thickness, and yet we are to suppose that it was able to depress the land for some feet below its present level--that is to say, for feet below its assumed pre-glacial elevation. either the ice depressed the crust to that remarkable extent, or the land upon which the ice accumulated was not nearly so high as the advocates of the "earth-movement hypothesis" have supposed. but the average i have taken for the thickness of the scottish ice-sheet is excessive, for it was only in the low-grounds that the _mer de glace_ attained such a depth. a large part of our country, however, is mountainous, and the mountain-tops were, of course, not nearly so thickly mantled with ice as the valleys. and the same to even a larger extent holds good for the scandinavian peninsula. if we take the thickness of the scandinavian ice-sheet that coalesced with that of scotland as feet, we shall be over the mark. now, i ask, is it possible to believe that a sheet of ice of that thickness actually pressed down the crust of the earth for not less than feet? but if we accept the "earth-movement hypothesis," as it has been recently advocated, that is what we must believe. if we cannot do so, then we cannot accept the assumption of great elevation of the land in pre-glacial and glacial times. let me put the case shortly: if the glacial marine beds and raised beaches of the atlantic borders of europe and north america owe their origin to depression induced by the weight of an ice-sheet, then it is quite certain that at the advent of glacial conditions the land could not have been so highly elevated as the advocates of the "earth-movement hypothesis" suppose. but if we are to accept the notion of great elevation of the land, then we must conclude that the submergence to which the raised beaches testify cannot have been caused by the pressure of ice-sheets. it is hardly necessary to pursue this particular subject further, but before leaving it, attention may be drawn for a moment to the curious conclusion that the ice-sheets were self-destructive. one is left to guess at what particular stage the sinking process began, but if the earth's crust were as readily deformed as the extreme views i have been examining would compel one to imply, then depression must have commenced almost immediately with the accumulation of snow and ice. the several ice-sheets must soon have attained their maximum thickness, and their disappearance must have been correspondingly rapid. and yet all the evidence goes to show that a glacial epoch endured for a comparatively long time--for a time sufficient to account for a prodigious amount of rock-erosion, and for the accumulation of vast sheets of glacial débris and fluvio-glacial detritus.[by] [by] it must not be inferred from the above remarks that i deny the possibility of deformation of the crust having been induced by the old ice-sheets. the geological evidence is certainly suggestive of such having been the case. but i much doubt whether the sinking of the surface was brought about by the mere weight of the ice pressing the crust down into a subjacent liquid layer. dr. drygalski's explanation would better account for the geological phenomena, but, according to rev. osmond fisher, it cannot be maintained. if it be difficult to understand how the "earth-movement hypothesis" can account for the origin of one glacial epoch, the difficulty is not lessened when we remember that there are two or more such epochs to account for. and until the advocates of that hypothesis can furnish us with some reliable evidence, they can hardly expect us to believe in their mysterious upheavals and depressions of northern and temperate regions, and in the no less wonderfully rhythmic movements of the isthmus of panama. in fine, the views which i have been controverting seem to me to be untenable, inasmuch as they are founded on mere assumptions, and do not even give a reasonable and intelligible explanation of the phenomena of glaciated regions, while they practically ignore or leave unsolved the problem of interglacial conditions. some five-and-twenty years have now elapsed since my lamented friend and colleague, james croll, published his well-known physical theory of the glacial period. that theory, as you all know, has been frequently criticised by physicists and others, to whose objections croll made a final reply in his _climate and cosmology_. in that work he has successfully defended his views, and even added considerably to the strength of his general argument. i am not aware that since then any serious objections to croll's theory have appeared. the only one indeed that seems to have attracted attention is that which has been urged especially by certain american geologists. their belief is that the close of the glacial period must have taken place at a much more recent date than croll has inferred. and this belief of theirs is based upon various estimates which have been made as to the time required for the erosion of valleys and the accumulation of alluvial deposits since the glacial period. thus, according to mr. gilbert, the post-glacial gorge of niagara, at the present rate of erosion, must have been excavated within years; while mr. winchell, from similar measurements of the post-glacial erosion of the falls of st. anthony, concludes that years have elapsed since the close of the ice age. i might cite a number of similar estimates that tend to show that since the close of the glacial period only or , years have elapsed. what will archæologists say to this conclusion? we know that egypt was already occupied by a civilised people nearly years ago, and their marvellously advanced civilisation at that time presupposes, according to egyptologists, many thousands of years of development. are we, then, prepared to admit that the close of the ice age coincided with the dawn of egyptian civilisation? but all american observers are not so parsimonious with regard to post-glacial time. thus professor spencer has given the age of the falls of niagara as , years, and he informed me recently that this does not represent half of the time since the formation of the third great series of glacial deposits of the canadian uplands. in our own continent similar estimates have been based on the rate of erosion of river-valleys, the rate of accumulation of alluvial deposits, of peat-bogs, of stalagmite in caves, and what not, with results that, to say the least, are rather discordant. the fact is that all such measurements and estimates, however carefully conducted and cautiously made, are in the nature of things unreliable. we are insufficiently acquainted with all the factors of the problem to be solved, and i cannot therefore agree with those who attribute much weight to conclusions based on such uncertain data. dr. croll's theory may eventually be modified, but i feel sure that it will not be overturned by the inconclusive and unsatisfactory estimates to which i have referred. moreover, opponents of that theory may be reminded that its truth does not rest on the accuracy of its author's conclusion as to the date of the last ice age. that periods of high eccentricity of the earth's orbit have occurred is beyond all doubt, but whether the formulæ employed by croll in calculating the date of the last great cycle can be relied upon for that purpose is quite another question. at present, so far as i understand the facts, the glacial and the interglacial phenomena are explained by the astronomical theory, and by no other. it gives a simple, coherent, and consistent interpretation of the climatic vicissitudes of the pleistocene and post-glacial periods, and in especial it is the only theory that throws any light on the very remarkable climates of interglacial times. x. the glacial succession in europe.[bz] [bz] _trans. royal soc. edinburgh_, vol. xxxvii. ( ). for many years geologists have recognised the occurrence of at least two boulder-clays in the british islands and the corresponding latitudes of the continent. it is no longer doubted that these are the products of two separate and distinct glacial epochs. this has been demonstrated by the appearance of intercalated deposits of terrestrial, freshwater, or, as the case may be, marine origin. such interglacial accumulations have been met with again and again in britain, and they have likewise been detected at many places on the continent, between the border of the north sea and the heart of russia. their organic contents indicate in some cases cold climatic conditions; in others, they imply a climate not less temperate or even more genial than that which now obtains in the regions where they occur. nor are such interglacial beds confined to northern and north-western europe. in the alpine lands of the central and southern regions of our continent they are equally well developed. impressed by the growing strength of the evidence, it is no wonder that geologists, after a season of doubt, should at last agree in the conclusion that the glacial conditions of the pleistocene period were interrupted by at least one protracted interglacial epoch. not a few observers go further, and maintain that the evidence indicates more than this. they hold that three or even more glacial epochs supervened in pleistocene times. this is the conclusion i reached many years ago, and i now purpose reviewing the evidence which has accumulated since then, in order to show how far it goes to support that conclusion. in our islands we have, as already remarked, two boulder-clays, of which the lower or older has the wider extension southwards, for it has been traced as far as the valley of the thames. the upper boulder-clay, on the other hand, does not extend south of the midlands of england. in the north of england, and throughout scotland and the major portion of ireland, it is this upper boulder-clay which usually shows at the surface. the two clays, however, frequently occur together, and are exposed again and again in deep artificial and natural sections, as in pits, railway-cuttings, quarries, river-banks, and sea-cliffs. sometimes the upper clay rests directly upon the lower; at other times they are separated by alluvial and peaty accumulations or by marine deposits. the wider distribution of the lower till, the direction of transport of its included erratics, and the trend of the underlying _roches moutonnées_ and rock-striæ, clearly show that the earlier _mer de glace_ covered a wider area than its successor, and was confluent on the floor of the north sea with the scandinavian ice-sheet. it was during the formation of the lower till, in short, that glaciation in these islands attained its maximum development. the interglacial beds, which in many places separate the lower from the upper till, show that after the retreat of the earlier _mer de glace_ the climate became progressively more temperate, until eventually the country was clothed with a flora essentially the same as the present. wild oxen, the great irish deer, and the horse, elephant, rhinoceros, and other mammals then lived in britain. from the presence of such a flora and fauna we may reasonably infer that the climate during the climax of interglacial times was as genial as now. the occurrence of marine deposits associated with some of the interglacial peaty beds shows that eventually submergence ensued; and as the shells in some of the marine beds are boreal and arctic forms, they prove that cold climatic conditions accompanied the depression of the land. to what extent the land sank under water we cannot tell. it may have been feet or not so much, for the evidence is somewhat unsatisfactory. the upper boulder-clay of our islands is the product of another _mer de glace_, which in scotland would seem to have been hardly less thick and extensive than its predecessor. like the latter, it covered the whole country, overflowed the outer hebrides, and became confluent with the scandinavian inland-ice on the bed of the north sea. but it did not flow so far to the south as the earlier ice-sheet. it is well known that this later _mer de glace_ was succeeded in our mountain-regions by a series of large local glaciers, which geologists generally believe were its direct descendants. it is supposed, in short, that the inland-ice, after retreating from the low-grounds, persisted for a time in the form of local glaciers in mountain-valleys. this view i also formerly held, although there were certain appearances which seemed to indicate that, after the ice-sheet had melted away from the lowlands and shrunk far into the mountains, a general advance of great valley-glaciers had taken place. i had observed, for example, that the upper boulder-clay is often well developed in the lower reaches of our mountain-valleys--that, in fact, it may be met with more or less abundantly up to the point at which large terminal moraines are encountered. more than this, i had noticed that upland valleys, in which no local or terminal moraines occur, are usually clothed and paved with boulder-clay throughout. again, the aspect of valleys which have been occupied by large local glaciers is very suggestive. above the point at which terminal moraines occur only meagre patches of till are met with on the bottoms of the valleys. the adjacent hill-slopes up to a certain line may show bare rock, sprinkled perchance with erratics and superficial morainic detritus; but above this line, if the acclivity be not too great, boulder-clay often comes on again. these appearances are most conspicuously displayed in the southern uplands of scotland, particularly in south ayrshire and galloway, and long ago they led me to suspect that the local glaciers into which our latest _mer de glace_ was resolved, after retreating continuously towards the heads of their valleys, so as to leave the boulder-clay in a comparatively unmodified condition, had again advanced and ploughed this out, down to the point at which they dropped their terminal moraines. subsequent observations in the highlands and the inner and outer hebrides confirmed me in my suspicion, for in all those regions we meet with phenomena of precisely the same kind. my friends and colleagues, messrs. peach and horne, had independently come to a similar conclusion; and the more recent work of the geological survey in the north-west highlands, as they inform me, has demonstrated that after the dissolution of the general ice-sheet underneath which the upper boulder-clay was accumulated, a strong recrudescence of glacial conditions supervened, and a general advance of great valley-glaciers took place--the glaciers in many places coalescing upon the low-grounds to form united _mers de glace_ of considerable extent. the development of these large glaciers, therefore, forms a distinct stage in the history of the glacial period. they were of sufficient extent to occupy all the fiords of the northern and western highlands, at the mouths of which they calved their icebergs, and they descended the valleys on the eastern slopes of the land into the region of the great lakes, at the lower ends of which we encounter their outermost terminal moraines. the shetland and orkney islands and the inner and outer hebrides at the same time nourished local glaciers, not a few of which flowed into the sea. such, for example, was the case in skye, harris, south uist, and arran. the broad uplands of the south were likewise clothed with snow-fields that fed numerous glaciers. these were especially conspicuous in the wilds of galloway, but they appeared likewise in the peeblesshire hills; and even in less elevated tracts they have left more or less well-marked traces of their former presence. it is to this third epoch of glaciation that i would assign the final scooping out of our lake-basins and the completion of the deep depressions in the beds of our highland fiords. all the evidence, indeed, leads to the conviction that the epoch was one of long duration. it goes without saying that what holds good for scotland must, within certain limits, hold good also for ireland and england. in wales and the cumberland lake district, and in the mountain-regions of the sister island, we meet with evidence of similar conditions. each of those areas has obviously experienced intense local glaciation subsequent to the disappearance of the last big ice-sheet. attention must now be directed to another series of facts which help us to realise the general conditions that obtained during the epoch of local glaciation. in the basin of the estuary of the clyde, and at various other places both on the west and east coasts of scotland, occur certain clays and sands, which overlie the upper boulder-clay, and in some places are found wrapping round the kames and osar of the last great ice-sheet. these beds are charged with the relics of a boreal and arctic fauna, and indicate a submergence of rather more than feet. in the lower reaches of the rivers clyde, forth, and tay the clays and sands form a well-marked terrace, and a raised sea-beach, containing similar organisms, occurs here and there on the sea-coast, as between dundee and arbroath, on the southern shores of the moray firth, and elsewhere. when the terraces are traced inland they are found to pass into high-level fluviatile gravels, which may be followed into the mountain-valleys, until eventually they shade off into fluvio-glacial detritus associated with the terminal moraines of the great local glaciers. it is obvious, in short, that the epoch of local ice-sheets and large valley-glaciers was one also of partial submergence. this is further shown by the fact that in some places the glaciers that reached the sea threw down their moraines on the -feet beach. it must have been an epoch of much floating ice, as the marine deposits contain now and again many erratics, large and small, and are, moreover, frequently disturbed and contorted as if from the grounding of pack-ice. the phenomena which i have thus briefly sketched suffice to show that the epoch of local glaciation is to be clearly distinguished from that of the latest general _mer de glace_. i have long suspected, indeed, that the two may have been separated by as wide an interval of time as that which divided the earlier from the later epoch of general glaciation. again and again i have searched underneath the terminal moraines, in the faint hope of detecting interglacial accumulations. my failure to discover these, however, did not weaken my conviction, for it was only by the merest chance that interglacial beds could ever have been preserved in such places. i feel sure, however, that they must occur among the older alluvia of our lowlands. indeed, as i shall point out in the sequel, it is highly probable that they are already known, and that we have hitherto failed to recognise their true position in the glacial series. although we have no direct evidence to prove that a long interglacial epoch of mild conditions immediately preceded the advent of our local ice-sheets and large valley-glaciers, yet the indirect evidence is so strong that we seem driven to admit that such must have been the case. to show this i must briefly recapitulate what is now known as to the glacial succession on the continent. it has been ascertained, then, that the scandinavian ice has invaded the low-grounds of germany on two separate occasions, which are spoken of by continental geologists as the "first" and "second" glacial epochs. the earlier of these was the epoch of maximum glaciation, when the inland ice flowed south into saxony, and overspread a vast area between the borders of the north sea and the base of the ural mountains. this ice-sheet unquestionably coalesced with the _mer de glace_ of the british islands. its bottom-moraine and the associated fluvio-glacial detritus are known in germany as "lower diluvium," and the various phenomena connected with it clearly show that the inland-ice radiated outwards from the high-grounds of scandinavia. the terminal front of that vast _mer de glace_ is roughly indicated by a line drawn from the south coast of belgium round the north base of the harz, and by leipzig and dresden to krakow, thence north-east to nijnii novgorod, and further north to the head-waters of the dvina and the shores of the arctic sea near the tcheskaia gulf. the lower diluvium is covered in certain places by interglacial deposits and an overlying upper diluvium--a succession clearly indicative of climatic changes. in the interglacial beds occur remains of _elephas antiquus_ and other pleistocene mammals, and a flora which denotes a genial temperate climate. one of the latest discoveries of interglacial remains is that of two peat-beds lying between the lower and upper diluvium near grünenthal in holstein.[ca] among the abundant plant-relics are pines and firs (no longer indigenous to schleswig-holstein), aspen, willow, white birch, hazel, hornbeam, oak, and juniper. associated with these are _ilex_ and _trapa natans_, the presence of which, as dr. weber remarks, betokens a climate like that of western middle germany. amongst the plants is a water-lily, which occurs also in the interglacial beds of switzerland, but is not now found in europe. the evidence furnished by this and other interglacial deposits in north germany shows that, after the ice-sheet of the lower diluvium had melted away, the climate became as temperate as that now experienced in europe. another recent find of the same kind[cb] is the "diluvial" peat, etc., of klinge, in brandenburg, described by professor nehring. these beds have yielded remains of elk (_cervus alces_), rhinoceros (species not determined), a small fox (?), and megaceros. this latter is not the typical great irish deer, but a variety (_c. megaceros_, var. _ruffii_, nehring). the plant-remains include pine, fir (_picea excelsa_), hornbeam, warty birch (_betula verrucosa_), various willows (_salix repens_, _s. aurita_, _s. caprea_ [?], _s. cinerea_), hazel, poplar (?), common holly, etc. it is worthy of note that here also the interglacial water-lily (_cratopleura_) of schleswig-holstein and switzerland makes its appearance. dr. weber writes me that the facies of this flora implies a well-marked temperate insular climate (seeklima). the occurrence of holly in the heart of the continent, where it no longer grows wild, is particularly noteworthy. the evidence furnished by such a flora leads one to conclude that at the climax of the genial interglacial epoch, the scandinavian snow-fields and glaciers were not more extensive than they are at present. [ca] _neues jahrbuch f. min. geol. u. palæont._, , ii., pp. , ; _ibid._, , i., p. . [cb] _naturwissenschaftliche wochenschrift_, bd. vii. ( ), no. , p. . the plants were determined by dr. weber, professor wittmack, and herr warnstorf. [more recent investigations have considerably increased our knowledge of this flora. see _naturwissenschaftliche wochenschrift_, bd. vii. ( ), nr. , . _ausland_, , nr. ; _neues jahrb. f. min., etc._, , bd. i., p. .] the presence of the upper diluvium, however, proves that such genial conditions eventually passed away, and that an ice-sheet again invaded north germany. but this later invasion was not on the same scale as that of the preceding one. the geographical distribution of the upper diluvium and the position of large terminal moraines put this quite beyond doubt. the boulder-clay in question spreads over the baltic provinces of germany, extending south as far as berlin,[cc] and west into schleswig-holstein and denmark. at the climax of this later cold epoch glaciers occupied all the fiords of norway, but did not advance beyond the general coast-line. norway at that time must have greatly resembled greenland--the inland-ice covering the interior of the country, and sending seawards large glaciers that calved their icebergs at the mouths of the great fiords. in the extreme south, however, the glaciers did not quite reach the sea, but piled up large terminal moraines on the coast-lands, which may be followed thence into sweden in an easterly direction by the lower end of lake wener and through lake wetter. a similar belt of moraines marks out the southern termination of the ice-sheet in finland. between sweden and finland lies the basin of the baltic, which, at the epoch in question was filled with ice, forming a great baltic glacier. this glacier overflowed the Öland islands, gottland, and Öland, fanning out as it passed towards the south-west and west, so as to invade on the south the baltic provinces of germany, while in the north it traversed the southern part of scania, and overwhelmed the danish islands as it spread into jutland and schleswig-holstein. the course of this second ice-sheet is indicated by the direction of transport of erratics, etc., and by the trend of rock-striæ and _roches moutonnées_, as well as by the position of its terminal and lateral moraines. [cc] not quite so far south. there is no reason to believe that the ice-sheet of the so-called great baltic glacier advanced beyond the baltic ridge. the upper boulder-clay south of that ridge is the ground-moraine of an earlier glaciation--the equivalent of our upper boulder-clay. see note, page . nov. , . such, then, is the glacial succession which has been established by geologists in scandinavia, north germany, and finland. the occurrence of two glacial epochs, separated by a long interval of temperate conditions, has been proved. the evidence, however, does not show that there may not have been more than two glacial epochs. there are certain phenomena, indeed, connected with the glacial accumulations of the regions in question which strongly suggest that the succession of changes was more complex than is generally understood. several years ago dr. a. g. nathorst adduced evidence to show that a great baltic glacier, similar to that underneath which the upper diluvium was amassed, existed before the advent of the vast _mer de glace_ of the so-called "first glacial epoch,"[cd] and his observations have been confirmed and extended by h. lundbohm.[ce] the facts set forth by them prove beyond doubt that this early baltic glacier smoothed and glaciated the rocks in southern sweden in a direction from south-east to north-west, and accumulated a bottom-moraine whose included erratics are equally cogent evidence as to the trend of glaciation. that old moraine is overlaid by the lower diluvium--_i.e._, the boulder-clay, etc., of the succeeding vast _mer de glace_ that flowed south to the foot of the harz--the transport of the stones in the superjacent clay indicating a movement from nne. to ssw., or nearly at right angles to the trend of the earlier baltic glacier. it is difficult to avoid the conclusion that we have here to do with the products of two distinct ice-epochs. but hitherto no interglacial deposits have been detected between the boulder-clays in question. it might, therefore, be held that the early baltic glacier was separated by no long interval of time from the succeeding great _mer de glace_, but may have been merely a stage in the development of the latter. it is at all events conceivable that before the great _mer de glace_ attained its maximum extension, it might have existed for a time as a large baltic glacier. i would point out, however, that if no interglacial beds had been recognised between the lower and the upper diluvium, geologists would probably have considered that the last great baltic glacier was simply the attenuated successor of the preceding continental _mer de glace_. but we know this was not so; the two were actually separated by a long epoch of genial temperate conditions. [cd] "beskrifning. till geol. kartbl. trolleholm": _sveriges geologiska undersökning_, ser. aa., nr. . [ce] "om de äldre baltiska isströmmen i södra sverige": _geolog. förening. i stockholm förhandl._, bd. x., p. . there are certain other facts that may lead us to doubt whether in the glacial phenomena of the baltic coast-lands we have not the evidence of more than two glacial epochs. three, and even four, boulder-clays have been observed in east and west prussia. they are separated, the one from the other, by extensive aqueous deposits, which are sometimes fossiliferous. moreover, the boulder-clays in question have been followed continuously over considerable areas. it is quite possible, of course, that all those boulder-clays may be the product of one epoch, laid down during more or less considerable oscillations of an ice-sheet. in this view of the case the intercalated aqueous deposits would indicate temporary retreats, while the boulder-clays would represent successive re-advances of one and the same _mer de glace_. on the other hand, it is equally possible, if not more probable, that the boulder-clays and intercalated beds are evidence of so many separate glacial and interglacial epochs. we cannot yet say which is the true explanation of the facts. but these being as they are, we may doubt if german glacialists are justified in so confidently maintaining that their lower and upper diluvial accumulations are the products of the "first" and "second" glacial epochs. indeed, as i shall show presently, the upper diluvium of north germany and finland cannot represent the second glacial epoch of other parts of europe. for a long time it has been supposed that the glacial deposits of the central regions of russia were accumulated during the advance and retreat of one and the same ice-sheet. in , however, professor pavlow brought forward evidence to show that the province of nijnii novgorod had been twice invaded by a general _mer de glace_. during the first epoch of glaciation the ice-sheet overflowed the whole province, while only the northern half of the same region was covered by the _mer de glace_ of the second invasion. again, professor armachevsky has pointed out that in the province of tchernigow two types of glacial deposits appear, so unlike in character and so differently distributed that they can hardly be the products of one and the same ice-sheet. but until recently no interglacial deposits had been detected, and the observations just referred to failed, therefore, to make much impression. the missing link in the material evidence has now happily been supplied by m. krischtafowitsch.[cf] at troïzkoje, in the neighbourhood of moscow, occur certain lacustrine formations which have been long known to russian geologists. these have been variously assigned to tertiary, lower glacial, post-glacial, and pre-glacial horizons. they are now proved, however, to be of interglacial age, for they rest upon and are covered by glacial accumulations. amongst their organic remains are oak (_quercus pedunculata_), alder (_alnus glutinosa_, _a. incana_), white birch, hazel, norway maple (_acer platanoides_), scots fir, willow, water-lilies (_nuphar_, _nymphæa_), mammoth, pike, perch, _anadonta_, wing-cases of beetles, etc. the character of the plants shows that the climate of central russia was milder and more humid than it is to-day. [cf] _bull. de la soc. impér. des naturalistes de moskau_, no. , . it is obvious that the upper and lower glacial deposits of central russia cannot be the equivalents of the upper and lower diluvium of the baltic coast-lands. the upper diluvium of those regions is the bottom-moraine of the so-called great baltic glacier. at the time that glacier invaded north germany, finland was likewise covered with an ice-sheet, which flowed towards the south-east, but did not advance quite so far as the northern shores of lake ladoga. a double line of terminal moraines, traced from hango head on the gulf of finland, north-east to beyond joensuu, puts this beyond doubt.[cg] the morainic deposits that overlie the interglacial beds of central russia cannot, therefore, belong to the epoch of the great baltic glacier. they are necessarily older. in short, it is obvious that the upper and lower glacial accumulations near moscow must be on the horizon of the lower diluvium of north germany. and if this be so, then it is clear that the latter cannot be entirely the product of one and the same _mer de glace_. when the several boulder-clays described by schröder and others as occurring in the baltic provinces of germany are reinvestigated, they may prove to be the bottom-moraines of as many distinct and separate glacial epochs. [cg] sederholm, _fennia_, i., no. ; frosterus, _ibid._, iii., no. ; ramsay, _ibid._, iv., no. . it may be contended that the glacial and interglacial deposits of central russia are perhaps only local developments--that their evidence may be accounted for by the oscillations of one single _mer de glace_. this explanation, as already pointed out, has been applied to the boulder-clays and intercalated aqueous beds of the lower diluvium of north germany, and the prevalent character of the associated organic remains makes it appear plausible. it is quite inapplicable, however, to the similar accumulations in central russia. during the formation of the freshwater beds of troïzkoje, no part of russia could have been occupied by an ice-sheet; the climate was more genial and less "continental" than the present. yet that mild interglacial epoch was preceded and succeeded by extremely arctic conditions. it is impossible that such excessive changes could have been confined to central russia. germany, and indeed all northern and north-western europe, must have participated in the climatic revolutions. so far, then, as the evidence has been considered, we may conclude that three glacial and two interglacial epochs at least have been established for northern europe. if this be the case, then a similar succession ought to occur in our own islands; and a little consideration of the evidence already adduced will suffice to show that it does. it will be remembered that the lower and upper boulder-clays of the british islands are the bottom-moraines of two separate and distinct ice-sheets, each of which in its time coalesced on the floor of the north sea with the inland-ice of scandinavia. it is obvious, therefore, that our upper boulder-clay cannot be the equivalent of the upper diluvium of the baltic coast-lands, of sweden, denmark, and schleswig-holstein. de geer and others have shown that while the great baltic glacier was accumulating the upper diluvium of north germany, etc., the inland-ice of norway calved its icebergs at the mouths of the great fiords. thus, during the so-called "second" glacial epoch of scandinavian and german geologists, the norwegian inland-ice did not coalesce with any british _mer de glace_. the true equivalent in this country of the upper diluvium is not our upper boulder-clay, but the great valley-moraines of our mountain-regions. it is our epoch of large valley-glaciers which corresponds to that of the great baltic ice-flow. our upper and lower boulder-clays are on the horizon of the lower diluvium of germany and the glacial deposits of central russia. it will now be seen that the evidence in britain is fully borne out by what is known of the glacial succession in the corresponding latitudes of the continent. i had inferred that our epoch of large valley-glaciers formed a distinct stage by itself, and was probably separated from that of the preceding ice-sheet by a prolonged interval of interglacial conditions. one link in the chain of evidence, however, was wanting: i could not point to the occurrence of interglacial deposits underneath the great valley-moraines. but these, as we have seen, form a well-marked horizon on the continent, and we cannot doubt that a similar interglacial stage obtained in these islands. we may feel confident, in fact, that genial climatic conditions supervened on the dissolution of the last great _mer de glace_ in britain, and that the subsequent development of extensive snow-fields and glaciers in our mountain-regions was contemporaneous with the appearance of the last great baltic glacier. we need not be surprised that interglacial beds should be well developed underneath the bottom-moraine of that great glacier, while they have not yet been recognised below the corresponding morainic accumulations of our highlands and uplands. the conditions in the low-grounds of the baltic coast-lands favoured their preservation, for the ice in those regions formed a broad _mer de glace_, under the peripheral areas of which sub-glacial erosion was necessarily at a minimum and the accumulation at a maximum. in our scottish mountain-valleys, however, the very opposite was the case. the conditions obtaining there were not at all comparable to those that characterised the low-grounds of northern germany, etc., but were quite analogous to those of norway, where, as in our own mountain-regions, interglacial beds are similarly wanting. it is quite possible, however, that patches of such deposits may yet be met with underneath our younger moraines, and they ought certainly to be looked for. but whether they occur or not in our mountain-valleys, it is certain that some of the older alluvia of our lowlands must belong to this horizon. hitherto all alluvial beds that overlie our upper boulder-clay have been classified as post-glacial; but since we have ascertained that our latest _mer de glace_ was succeeded by genial interglacial conditions, we may be sure that records of that temperate epoch will yet be recognised in such lowland tracts as were never reached by the glaciers of the succeeding cold epoch. hence, i believe that some of our so-called "post-glacial" alluvia will eventually be assigned to an interglacial horizon. amongst these may be cited the old peat and freshwater beds that rest upon the upper boulder-clay at hailes quarry, near edinburgh. to the same horizon, in all probability, belong the clays, with megaceros, etc., which occur so frequently underneath the peat-bogs of ireland. an interesting account of these was given some years ago by mr. williams,[ch] who, as a collector of megaceros remains, had the best opportunity of ascertaining the nature of the deposits in which these occur. he gives a section of ballybetagh bog, nine miles south-east of dublin, which is as follows:-- . boulder-clay. . fine tenacious clay, without stones. . yellowish clay, largely composed of vegetable matter. . brownish clay, with remains of megaceros. . greyish clay. . peat. [ch] _geol. mag._, , p. . the beds overlying the boulder-clay are evidently of lacustrine origin. the fine clay (no. ), according to mr. williams, is simply reconstructed boulder-clay. after the disappearance of the _mer de glace_ the land would for some time be practically destitute of any vegetable covering, and rain would thus be enabled to wash down the finer ingredients of the boulder-clay that covered the adjacent slopes, and sweep them into the lake. the clay formed in this way is described as attaining a considerable thickness near the centre of the old lake, but it thins off towards the sides. the succeeding bed (no. ) consists so largely of vegetable débris that it can hardly be called a clay. mr. williams describes it as a "bed of pure vegetable remains that has been ages under pressure." he notes that there is a total absence in this bed of any tenacious clay like that of the underlying stratum, and infers, therefore, that the rainfall during the growth of the lacustrine vegetation was not so great as when the subjacent clay was being accumulated. the remains of megaceros occur resting on the surface of the plant-bed and at various levels in the overlying brownish clay, which attains a thickness of three to four feet. the latter is a true lacustrine sediment, containing a considerable proportion of vegetable matter, interstratified with seams of clay and fine quartz-sand. according to mr. williams, it was accumulated under genial or temperate climatic conditions like the present. between this bed and the overlying greyish clay (from inches to feet thick) there is always in all the bog deposits examined by mr. williams a strongly-marked line of separation. the greyish clay consists exclusively of mineral matter, and has evidently been derived from the disintegration of the adjacent granitic hills. mr. williams is of opinion that this clay is of aqueo-glacial formation. this he infers from its nature and texture, and from its abundance. "why," he asks, "did not this mineral matter come down in like quantity all the time of the deposit of the brown clay which underlies it? simply because, during the genial conditions which then existed, the hills were everywhere covered with vegetation; when the rain fell it soaked into the soil, and the clay being bound together by the roots of the grasses, was not washed down, just as at the present time, when there is hardly any degradation of these hills taking place." he mentions, further, that in the grey clay he obtained the antler of a reindeer, and that in one case the antlers of a megaceros, found embedded in the upper surface of the brown clay, immediately under the grey clay, were scored like a striated boulder, while the under side showed no markings. mr. williams also emphasises the fact that the antlers of megaceros frequently occur in a broken state--those near the surface of the brown clay being most broken, while those at greater depths are much less so. he shows that this could not be the result of tumultuous river-action--the elevation of the valley precluding the possibility of its receiving a river capable of producing such effects. moreover, the remains show no trace of having been water-worn, the edges of the teeth of the great deer being as sharp as if the animal had died but yesterday. mr. williams thinks that the broken state of the antlers is due to the "pressure of great masses of ice on the surface of the clay in which they were embedded, the wide expanse of the palms of the antlers exposing them to pressure and liability to breakage; and even, in many instances, when there was or inches in circumference of solid bone almost as hard and sound as ivory, it was snapped across." it is remarkable that in this one small bog nearly one hundred heads of megaceros have been dug up. mr. williams' observations show us that the megaceros-beds are certainly older than the peat-bogs with their buried timber. when he first informed me of the result of his researches ( ), i did not believe the megaceros-beds could be older than the latest cold phase of the ice age. i thought that they were later in date than our last general _mer de glace_, and i think so still, for they obviously rest upon its ground-moraine. but since i now recognise that our upper boulder-clay is not the product of the last glacial epoch, it seems to me highly probable that the megaceros-beds are of interglacial age--that, in short, they occupy the horizon of the interglacial deposits of north germany, etc. the appearances described by mr. williams in connection with the "grey clay" seem strongly suggestive of ice-action. ballybetagh bog occurs at an elevation of feet above the sea, in the neighbourhood of the three rock mountain ( feet), and during the epoch of great valley-glaciers the climatic conditions of that region must have been severe. but without having visited the locality in question i should hesitate to say that the phenomena necessarily point to local glaciation. probably frost, lake-ice, and thick accumulations of snow and _névé_ might suffice to account for the various facts cited by mr. williams. i have called special attention to these irish lacustrine beds, because it is highly probable that the post-glacial age of similar alluvia occurring in many other places in these islands has hitherto been assumed and not proved. now that we know, however, that a long interglacial stage succeeded the disappearance of the last general _mer de glace_, we may feel sure that the older alluvia of our lowland districts cannot belong exclusively to post-glacial times. the local ice-sheets and great glaciers of our "third" glacial epoch were confined to our mountain-regions; and in the lowlands, therefore, which were not invaded, we ought to have the lacustrine and fluviatile accumulations of the preceding interglacial stage. a fresh interest now attaches to our older alluvia, which must be carefully re-examined in the new light thus thrown upon them. turning next to the alpine lands of central europe, we find that geologists there have for many years recognised two glacial epochs. hence, like their _confrères_ in northern europe, they speak of "first" and "second" glacial epochs.[ci] within recent years, however, professor penck has shown that the alps have experienced at least three separate periods of glaciation. he describes three distinct ground-moraines, with associated river-terraces and interglacial deposits in the valleys of the bavarian alps, and his observations have been confirmed by professor brückner and dr. böhm.[cj] the same glacialists, i understand, have nearly completed an elaborate survey of the eastern alps, of which they intend shortly to publish an extended account. the results obtained by them are very interesting, and fully bear out the conclusions already arrived at from their exploration of the bavarian alps.[ck] a similar succession of glacial epochs has quite recently been determined by dr. du pasquier in north switzerland.[cl] nor is this kind of evidence confined to the north side of the alps. on the shores of lake garda, between salò and brescia, three ground-moraines, separated by interglacial accumulations, are seen in section. the interglacial deposits consist chiefly of loams--the result of sub-aërial weathering--and attain a considerable thickness. from this penck infers that the time which has elapsed since the latest glaciation is less than that required for the accumulation of either of the two interglacial series--a conclusion which, he says, is borne out by similar observations in other parts of the alpine region.[cm] [ci] morlot: _bulletin de la soc. vaud. d. sciences nat._, , , . deicke: _bericht. d. st. gall. naturf. ges._, . heer: _urwelt der schweiz._ mühlberg: _festschrift d. aarg. naturf. ges. z. feier ihrer sitz._, . rothpletz: _denkschr. d. schweizer. ges. f. d. ges. naturwissensch._, bd. xxviii., . wettstein: _geologie v. zurich u. umgebung_, . baltzer: _mitteil. d. naturf. ges. bern_, . renevier: _bull. de la soc. helvèt. d. sciences nat._, . [cj] penck: _die vergletscherung d. deutschen alpen_, . brückner: "die vergletscherung des salzachgebietes," _geogr. abhandl. wien_, bd. i. böhm: _jahrb. der k. k. geol. reichsanst._, , . see also o. fraas, _neues jahrb. f. min. geol. u. palæont._, , bd. i. p. ; e. fugger and c. kastner, _verhandl. d. k. k. geol. reichsanst._, , p. . [ck] _mittheil. des deutsch. u. oesterreich. alpenvereins_, , no. u. . [cl] _beiträge z. geolog. karte der schweiz_, lief., ; _archiv. d. sciences phys. et nat._, , p. . [cm] "die grosse eiszeit," _himmel u. erde_. although the occurrence of such sub-äerial products intercalated between separate morainic accumulations is evidence of climatic changes, still it does not tell us how far the glaciers retreated during an interglacial stage. fortunately, however, lignite beds and other deposits charged with plant remains are met with occupying a similar position, and from these we gather that during interglacial times the glaciers sometimes retired to the very heads of the mountain-valleys, and must have been smaller than their present representatives. of such interglacial plant-beds, which have been met with in some twenty localities, the most interesting, perhaps, is the breccia of hötting, in the neighbourhood of innsbruck.[cn] this breccia rests upon old morainic accumulations, and is again overlaid by the later moraines of the great inn glacier. from the fact that the breccia yielded a number of supposed extinct species of plants, palæontologists were inclined to assign it to the pliocene. professor penck, however, prefers to include it in the pleistocene system, along with all the glacial and interglacial deposits of the alpine lands. according to dr. von wettstein, the flora in question is not alpine but pontic. at the time of the formation of the breccia the large-leaved _rhododendron ponticum_ flourished in the inn valley at a height of metres above the sea; the whole character of the flora, in short, indicates a warmer climate than is now experienced in the neighbourhood of innsbruck. it is obvious, therefore, that in interglacial times the glaciers must have shrunk back, as professor penck remarks, to the highest ridges of the mountains. [cn] penck: _die vergletscherung der deutschen alpen_, p. . _verhandl. d. k. k. geol. reichsanst._, , no. ; _himmel und erde_, . böhm: _jahrb. d. k. k. geol. reichsanst._, , p. . blaas: _ferdinandeums zeitschr._, iv. folge; _bericht. d. naturwissensch. vereins_, , p. . we may now glance at the glacial succession which has been established for central france. more than twenty years ago dr. julien brought forward evidence to show that the region of the puy de dôme had witnessed two glacial epochs.[co] during the first of these epochs a large glacier flowed from mont dore. after its retreat a prolonged interglacial epoch followed, during which the old morainic deposits and the rocks they rest upon were much eroded. in the valleys and hollows thus excavated freshwater beds occur which have yielded relics of an abundant flora, together with the remains of _elephas meridionalis_, _rhinoceros leptorhinus_, etc. after the deposition of these freshwater alluvia, glaciers again descended the valleys and covered the interglacial beds with their moraines. similar results have been obtained by m. rames from a study of the glacial phenomenon of cantal, which he shows belong to two separate epochs.[cp] the interval between the formation of the two series of glacial accumulations must have been prolonged, for the valleys during that interval were in some places eroded to a depth of feet. m. rames further recognises that the second glacial epoch was distinguished by two advances of valley-glaciers, separated by a marked episode of fusion. dr. julien has likewise noted the evidence for two episodes of fusion during the first extension of the glaciers of the puy de dôme. [co] _des phénomènes glaciaires dans le plateau central de la france_, &c.; paris, . [cp] bull. _soc. géol. de france_, ; see also m. boule, _bull. de la soc. philomath. de paris_, ^e sér. i., p. . two glacial epochs have similarly been admitted for the pyrenees;[cq] but dr. penck some years ago brought forward evidence to show that these mountains, like the alps, have experienced three separate and distinct periods of glaciation.[cr] [cq] garrigou: _bull. soc. géol. de france_, ^e sér. xxiv., p. . jeanbernat: _bull. de soc. d'hist. nat. de toulouse_, iv., pp. , . piette: _bull. soc. géol. de france_, ^e sér. ii., pp. , . [cr] _mitteilungen d. vereins f. erdkunde zu leipzig_, . we may now return to scotland, and consider briefly the changes that followed upon the disappearance of the local ice-sheets and large valley-glaciers of our mountain-regions. the evidence is fortunately clear and complete. in the valley of the tay, for example, at and below perth, we encounter the following succession of deposits:-- . recent alluvia. . carse-deposits, feet above sea-level. . peat and forest bed. . old alluvia. . clays, etc., of -feet beach. . boulder-clay. the old alluvia ( ) are obviously of fluviatile origin, and show us that after the deposition of the clays, etc., of the -feet beach the sea retreated, and allowed the tay and its tributaries to plough their way down through the marine and estuarine deposits of the "third" glacial epoch. these deposits would appear to have extended at first as a broad and approximately level plain over all the lower reaches of the valleys. through this plain the tay and the earn cut their way to a depth of more than feet, and gradually removed all the material over a course which can hardly be less than miles in breadth below the bridge of earn, and considerably exceeds that in the carse of gowrie. no organic remains occur in the "old alluvia," but the deposits consist principally of gravel and sand, and show not a trace of ice-action. immediately overlying them comes the well-known peat-bed ( ). this is a mass of vegetable matter, varying in thickness from a few inches up to or feet. in some places it seems to be made up chiefly of reed-like plants and sedges and occasional mosses, commingled with which are abundant fragments of birch, alder, willow, hazel, and pine. in other places it contains trunks and stools of oak and hazel, with hazel-nuts--the trees being rooted in the subjacent deposits. it is generally highly compressed and readily splits into laminæ, upon the surface of which many small reeds, and now and again wing-cases of beetles, may be detected. a large proportion of the woody débris--twigs, branches, and trunks--appears to have been drifted. a "dug-out" canoe of pine was found, along with trunks of the same tree, in the peat at perth. the carse-deposits ( ), consisting principally of clay and silt, rest upon the peat-bed. the occurrence in these deposits of _scrobicularia piperata_ and oyster-shells leaves us in no doubt as to their marine origin. they vary in thickness from up to fully feet.[cs] [cs] for a particular account of the tay-valley succession, see _prehistoric europe_, p. . a similar succession of deposits is met with in the valley of the forth,[ct] and we cannot doubt that these tell precisely the same tale. i have elsewhere[cu] adduced evidence to show that the peat-bed, with drifted vegetable débris, which underlies the carse accumulations of the forth and tay is on the same horizon as the "lower buried forest" of our oldest peat-bogs, and the similar bogs that occur in norway, sweden, denmark, schleswig-holstein, holland, etc. underneath the "lower buried forest" of those regions occur now and again freshwater clays, charged with the relics of an arctic-alpine flora; and quite recently similar plant remains have been detected in old alluvia at corstorphine, near edinburgh. when the beds below our older peat-bogs are more carefully examined, traces of that old arctic flora will doubtless be met with in many other parts of these islands. it was this flora that clothed north-western europe during the decay of the last district ice-sheets of britain and the disappearance of the great baltic glacier. [ct] _proc. roy. soc. edin._ - , p. ; _mem. geol. survey, scotland_, explanation of sheet . [cu] _prehistoric europe_, chaps. xvi., xvii. the dissolution of the large valley-glaciers of this country was accompanied by a general retreat of the sea--all the evidence leading to the conviction that our islands eventually became united to the continent. the climatic conditions, as evidenced by the flora of the "lower buried forest," were decidedly temperate--probably even more genial than they are now, for the forests attained at that time a much greater horizontal and vertical range. this epoch of mild climate and continental connection was eventually succeeded by one of submergence, accompanied by colder conditions. britain was again insulated--the sea-level in scotland reaching a height of - feet above present high-water. to this epoch pertain the carse-clays of the forth and tay. a few erratics occur in these deposits, probably betokening the action of floating ice, but the beds more closely resemble the modern alluvial silts of our estuaries than the tenacious clays of the -feet terrace. when the carse-clays are followed inland, however, they pass into coarse river-gravel and shingle, forming a well-marked high-level alluvial terrace of much the same character as the yet higher-level fluviatile terrace which is associated in like manner with the marine deposits of the -feet beach. of contemporaneous age with the carse-clays, with which indeed they are continuous, are the raised beaches at - feet. these beaches occur at many places along the scottish coasts, but they are seldom seen at the heads of our sea-lochs. when the sea stood at this level, glaciers of considerable size occupied many of our mountain-valleys. in the west they came down in places to the sea-coast, and dropped their terminal moraines upon the beach-deposits accumulating there. thus, in arran[cv] and in sutherland,[cw] these moraines are seen reposing on the raised beaches of that epoch. and i think it is probable that the absence of such beaches at the heads of many of the sea-lochs of the highland area is to be explained by the presence there of large glaciers, which prevented their formation. [cv] _british association reports_ ( ): trans. of sections, p. . [cw] l. hinxman: paper read before edin. geol. soc., april . thus, there is clear evidence to show that after the genial epoch represented by the "lower buried forest," a recrudescence of glacial conditions supervened in scotland. many of the small moraines that occur at the heads of our mountain-valleys, both in the highlands and southern uplands, belong in all probability to this epoch. they are characterised by their very fresh and well-preserved appearance.[cx] it is not at all likely that these later climatic changes could have been confined to scotland. other regions must have been similarly affected. but the evidence will probably be harder to read than it is with us. had it not been for the existence of our "lower buried forest," with the overlying carse-deposits, we could hardly have been able to distinguish so readily between the moraines of our "third" glacial epoch and those of the later epoch to which i now refer. the latter, we might have supposed, simply marked a stage in the final retreat of the antecedent great valley-glaciers. [cx] _prehistoric europe_ (chaps. xvi., xvii.) gives a fuller statement of the evidence. i have elsewhere traced the history of the succeeding stages of the pleistocene period, and adduced evidence of similar, but less strongly-marked, climatic changes having followed upon those just referred to, and my conclusions have been supported by the independent researches of professor blytt in norway. but these later changes need not be considered here. it is sufficient for my general purpose to confine attention to the well-proved conclusion that after the decay of the last district ice-sheets and great glaciers of our "third" glacial epoch genial conditions obtained, and that these were followed by cold and humid conditions, during the prevalence of which glaciers reappeared in many mountain-valleys. we have thus, as it seems to me, clear evidence in europe of four glacial epochs, separated the one from the other by protracted intervals of genial temperate conditions. so far, one's conclusions are based on data which cannot be gainsaid, but there are certain considerations which lead to the suspicion that the whole of the complex tale has not yet been unravelled, and that the climatic changes were even more numerous than those that i have indicated. let it be noted that glacial conditions attained their maximum during the earliest of our recognised glacial epochs. with each recurring cold period the ice-sheets and glaciers successively diminished in importance. that is one of the outstanding facts with which we have to deal. whatever may have been the cause or causes of glacial and interglacial conditions, it is obvious that those causes, after attaining a maximum influence, gradually became less effective in their operation. such having been the case, one can hardly help suspecting that our epoch of greatest glaciation may have been preceded by an alternation of cold and genial stages analogous to those that followed it. if three cold epochs of progressively diminished severity succeeded the epoch of maximum glaciation, the latter may have been preceded by one or more epochs of progressively increased severity. that something of the kind may have taken place is suggested by the occurrence of the old moraine of that great baltic glacier that preceded the appearance of the most extensive _mer de glace_ of northern europe. the old moraine in question, it will be remembered, underlies the lower diluvium. unfortunately, the very conditions that attended the glaciation of europe render it improbable that any conspicuous traces of glacial epochs that may have occurred prior to the period of maximum glaciation could have been preserved within the regions covered by the great inland-ice. their absence, therefore, cannot be held as proving that the lower boulder-clays of britain and northern europe are the representatives of the earliest glacial epoch. the lowest boulder-clay, i believe, has yet to be discovered. it is in the alpine lands that we encounter the most striking evidence of glacial conditions anterior to the epoch of maximum glaciation. the famous breccia of hötting has already been referred to as of interglacial age. from the character of its flora, ettinghausen considered this accumulation to be of tertiary age. the assemblage of plants is certainly not comparable to the well-known interglacial flora of dürnten. according to the researches of dr. r. von wettstein,[cy] the hötting flora has most affinity with that of the pontic mountains, the caucasus, and southern spain, and implies a considerably warmer climate than is now experienced in the inn valley. this remarkable deposit, as dr. penck pointed out some ten years ago, is clearly of interglacial age. his conclusions were at once challenged, on the ground that the flora had a tertiary and not a pleistocene facies; consequently, it was urged that, as all glacial deposits were of pleistocene age, this particular breccia could not be interglacial. but in this, as in similar cases, the palæontologist's contention has not been sustained by the stratigraphical evidence, and dr. penck's observations have been confirmed by several highly-competent geologists, as by mm. böhm and du pasquier. the breccia is seen in several well-exposed sections resting upon the moraine of a local glacier which formerly descended the northern flanks of the inn valley, opposite innsbruck, where the mountain-slopes under existing conditions are free from snow and ice. nor is this all, for certain erratics appear in the breccia, which could only have been derived from pre-existing glacial accumulations, and their occurrence in this accumulation at a height of metres shows that before the advent of the hötting flora the whole inn valley must have been filled with ice. the plant-bearing beds are in their turn covered by the ground-moraine of a later and more extensive glaciation. to bring about the glacial conditions that obtained before the formation of the breccia, the snow-line, according to penck, must have been at least metres lower than now; while, to induce the succeeding glaciation, the depression of the snow-line could not have been less than metres. these observations have been extended to many other parts of the alps, and the conclusion arrived at by professor penck and his colleagues, professor brückner and dr. böhm, is briefly this--that the maximum glaciation of those regions did not fall in the "first" but in the "second" alpine glacial epoch. [cy] _sitzungsberichte d. kais. acad. d. wissensch. in wien, mathem.-naturw. classe_, bd. xcvii. abth. i., . the glacial phenomena of northern and central europe are so similar--the climatic oscillations which appear to have taken place had so much in common, and were on so grand a scale--that we cannot doubt they were synchronous. we may feel sure, therefore, that the epoch of maximum glaciation in the alps was contemporaneous with the similar epoch in the north. and if this be so, then in the oldest ground-moraines of the alps we have the records of an earlier glacial epoch than that which is represented by the lower boulder-clays of britain and the corresponding latitudes of the continent. in other words, the hötting flora belongs to an older stage of the glacial period than any of the acknowledged interglacial accumulations of northern europe. the character of the plants is in keeping with this conclusion. the flora has evidently much less connection with the present flora of the alps than the interglacial floras of britain and northern europe have with those that now occupy their place. the hötting flora, moreover, implies a considerably warmer climate than now obtains in the alpine regions, while that of our interglacial beds indicates a temperate insular climate, apparently much like the present. the high probability that oscillations of climate preceded the advent of the so-called "first" _mer de glace_ of northern europe must lead to a re-examination of our pliocene deposits, with a view to see whether these yield conclusive evidence against such climatic changes having obtained immediately before pleistocene times. by drawing the line of separation between the pleistocene and the pliocene at the base of our glacial series, the two systems in britain are strongly marked off the one from the other. there is, in short, a distinct "break in the succession." from the cromer forest-bed, with its abundant mammalian fauna and temperate flora, we pass at once to the overlying arctic freshwater bed and the superjacent boulder-clay that marks the epoch of maximum glaciation.[cz] amongst the mammalian fauna of the forest-bed are elephants (_elephas meridionalis_, _e. antiquus_), hippopotamus, rhinoceros, (_r. etruscus_), horses, bison, boar, and many kinds of deer, together with such carnivores as bears, _machærodus_, spotted hyæna, etc. the freshwater and estuarine beds which contain this extensive fauna rest immediately upon marine deposits (weybourn crag), the organic remains of which have a decidedly arctic facies. here, then, we have what at first sight would seem to be another break in the succession. the forest-bed, one might suppose, indicated an interglacial epoch, separating two cold epochs. but mr. clement reid, who has worked out the geology of the pliocene with admirable skill,[da] has another explanation of the phenomena. it has long been known that the organic remains of the marine pliocene of britain denote a progressive lowering of temperature. the lower member of the system is crowded with southern forms, which indicate warm-temperate conditions. but when we leave the older and pass upwards into the newer pliocene those southern forms progressively disappear, while at the same time immigrants from the north increase in numbers, until eventually, in the beds immediately underlying the forest-bed, the fauna presents a thoroughly arctic facies. during the formation of the older pliocene with its southern fauna our area was considerably submerged, so that the german ocean had then a much wider communication with the seas of lower latitudes. at the beginning of newer pliocene times, however, the land emerged to some extent, and all connection between the german ocean and more southern seas was cut off. when at last the "forest-bed series" began to be accumulated, the southern half of the north sea basin had become dry land, and was traversed by the rhine in its course towards the north, the forest-bed representing the alluvial and estuarine deposits of that river. [cz] in some places, however, certain marine deposits (_leda myalis_ bed) immediately overlie the forest-bed. [da] _mem. of geol. survey_, "pliocene deposits of britain." _see postea_, footnote, p. . mr. reid, in referring to the progressive change indicated by the pliocene marine fauna, is inclined to agree with professor prestwich that this was not altogether the result of a general climatic change. he thinks the successive dying out of southern forms and the continuous arrival of boreal species was principally due to the north sea remaining fully open to the north, while all connection with southern seas was cut off. under such conditions, he says, "there was a constant supply of arctic species brought by every tide or storm, while at the same time the southern forms had to hold their own without any aid from without; and if one was exterminated it could not be replaced." doubtless the isolation of the north sea must have hastened the extermination of the southern forms, but the change could not have been wholly due to such local causes. similar, if less strongly-marked, changes characterise the marine pliocene of the mediterranean area, while the freshwater alluvia of france, etc., furnish evidence in the same direction. the cromer forest-bed overlies the weybourn crag, the marine fauna of which has a distinctly arctic facies. the two cannot, therefore, be exactly contemporaneous: the marine equivalents of the forest-bed are not represented. but mr. reid points out that several arctic marine shells of the weybourn crag occur also in the forest-bed, while certain southern freshwater and terrestrial shells common in the latter are met with likewise in the former, commingled with the prevailing arctic marine species. he thinks, therefore, that we may fairly conclude that the two faunas occupied adjacent areas. one can hardly accept this conclusion without reserve. it is difficult to believe that a temperate flora and mammalian fauna like those of the forest-bed clothed and peopled eastern england when the adjacent sea was occupied by arctic molluscs, etc. surely the occurrence of a few forms, which are common to the forest-bed and the underlying crag, does not necessarily prove that the two faunas occupied adjacent districts. mr. reid, indeed, admits that some of the marine shells in the forest-bed series may have been derived from the underlying crag. were the marine equivalents of the forest-bed forthcoming we might well expect them to contain many crag forms, but the facies of the fauna would most probably resemble that of the existing north sea fauna. again, the appearance in the weybourn crag of a few southern shells common to the forest-bed does not seem to prove more than that such shells were contemporaneous somewhere with an arctic marine fauna. but it is quite possible that they might have been carried for a long distance from the south; and, even if they actually existed in the near neighbourhood of an arctic marine fauna, we may easily attach too much importance to their evidence.[db] i cannot think, therefore, that mr. reid's conclusion is entirely satisfactory. after all, the cromer forest-bed rests upon the weybourn crag, and the evidence as it stands is explicable in another way. it is quite possible, for example, that the forest-bed really indicates an epoch of genial or temperate conditions, preceded, as it certainly was eventually succeeded, by colder conditions. [db] the inference that the forest-bed occupies an interglacial position is strengthened by the evidence of certain marine deposits which immediately overlie it. these (known collectively as the _leda myalis_ bed) occur in irregular patches, which, from the character of their organic remains, cannot all be precisely of the same age. in one place, for example, they are abundantly charged with oysters, having valves united, and with these are associated other species of molluscs that still live in british seas. at another place no oysters occur, but the beds yield two arctic shells, _leda myalis_ and _astarte borealis_, and some other forms which have no special significance. professor otto torell pointed out to mr. reid that these separate deposits could not be of the same age, for the oyster is sensitive to cold and does not inhabit the seas where _leda myalis_ and _astarte borealis_ flourish. from a consideration of this and other evidence mr. reid concludes that it is possible that the deposits indicate a period of considerable length, during which the depth of water varied and the climate changed. two additional facts may be noted: _leda myalis_ does not occur in any of the underlying pliocene beds, while the oyster is not found in the weybourn and chillesford crag, though common lower down in the pliocene series. these facts seem to me to have a strong bearing on the climatic conditions of the forest-bed epoch. they show us that the oyster flourished in the north sea before the period of the weybourn crag--that it did not live side by side with the arctic forms of that period--and that it reappeared in our seas when favourable conditions returned. when the climate again became cold an arctic fauna (including a new-comer, _leda myalis_) once more occupied the north sea. if it be objected that this would include as interglacial what has hitherto been regarded by most as a pliocene mammalian fauna,[dc] i would reply that the interglacial age of that fauna has already been proved in central france. the interglacial beds of auvergne, with _elephas meridionalis_, rest upon and are covered by moraines,[dd] and with these have been correlated the deposits of saint-prest. again, in northern italy the lignites of leffe and pianico, which, as i showed a number of years ago,[de] occupy an interglacial position, have likewise yielded _elephas meridionalis_ and other associated mammalian forms. [dc] _elephas meridionalis_ is usually regarded as a type-form of the newer pliocene, but long ago dr. fuchs pointed out that in hungary this species is of quaternary age: _verhandl. d. k. k. geolog. reichsanstalt_, , pp. , . it matters little whether we relegate to the top of the pliocene or to the base of the pleistocene the beds in which this species occurs. that it is met with upon an interglacial horizon is certain; and if we are to make the pleistocene co-extensive with the glacial and interglacial series we shall be compelled to include in that system some portion of the newer pliocene. [dd] julien: _des phènoménes glaciaires dans le plateau central_, etc., . boule: _revue d'anthropologie_, . [de] _prehistoric europe_, p. . professor penck writes me that he and the swiss glacialist, dr. du pasquier, have recently examined these deposits, and are able to confirm my conclusion as to their interglacial position. there can be no doubt, then--indeed it is generally admitted--that the cold conditions that culminated in our glacial period began to manifest themselves in pliocene times. moreover, as it can be shown that _elephas meridionalis_ and its congeners lived in central europe after an epoch of extensive glaciation, it is highly probable that the forest-bed, which contains the relics of the same mammalian fauna, is equivalent in age to the early interglacial beds of france and the alpine lands. we seem, therefore, justified in concluding that the alternation of genial and cold climates that succeeded the disappearance of the greatest of our ice-sheets was preceded by analogous climatic changes in late pliocene times. i shall now briefly summarise what seems to have been the glacial succession in europe:-- { . weybourn crag; ground-moraine of great baltic { glacier underlying lower diluvium; the oldest { recognised ground-moraines of central europe. { glacial { these accumulations represent the earliest { glacial epoch of which any trace has been { discovered. it would appear to have been one of { considerable severity, but not so severe as the { cold period that followed. { . forest-bed of cromer; hötting breccia; lignites { of leffe and pianico; interglacial beds of interglacial { central france. { { earliest recognised interglacial epoch; climate { very genial. { . lower boulder-clays of britain; lower diluvium { of scandinavia and north germany (in part); { lower glacial deposits of south germany and { central russia; ground-moraines and high-level { gravel-terraces of alpine lands, etc.; glacial { terminal moraines of outer zone. { { the epoch of maximum glaciation; the { british and scandinavian ice-sheets confluent; { the alpine glaciers attain their greatest development. { . interglacial freshwater alluvia, peat, lignite, etc., { with mammalian remains (britain, germany, { etc., central russia, alpine lands, etc.); and { marine deposits (britain, baltic coast-lands). interglacial { { continental condition of british area; climate { at first cold, but eventually temperate. submergence { ensued towards close of the period, { with conditions passing from temperate to { arctic. { . upper boulder-clay of britain; lower diluvium { of scandinavia, germany, etc., in part; upper { glacial series in central russia; ground-moraines { and gravel-terraces in alpine lands. { { scandinavian and british ice-sheets again glacial { confluent, but _mer de glace_ does not extend { quite so far as that of the preceding cold epoch. { conditions, however, much more severe than { those of the next succeeding cold epoch. { alpine glaciers deposit the moraines of the { inner zone. { . freshwater alluvia, lignite, peat, etc. (some of the { so-called post-glacial alluvia of britain; { interglacial beds of north germany, etc.; alpine { lands(?); marine deposits of britain and baltic { coast-lands). interglacial { { britain probably again continental; climate at { first temperate and somewhat insular; submergence { ensues with cold climatic conditions--scotland { depressed for feet; baltic provinces { of germany, etc., invaded by the waters of { the north sea. { . ground-moraines, terminal moraines, etc., of the { mountain regions of britain; upper diluvium { of scandinavia, finland, north germany, etc.; { great terminal moraines of same regions; terminal { moraines in the large longitudinal valleys { of the alps (penck). { { major portion of scottish highlands covered glacial { by ice-sheet; local ice-sheets in southern uplands { of scotland and mountain districts in { other parts of britain; great valley-glaciers { sometimes coalesce on low-grounds; icebergs { calved at mouths of highland sea-lochs; terminal { moraines dropped upon marine deposits { then forming ( -feet beach). scandinavia { shrouded in a great ice-sheet, which broke { away in icebergs along the whole west coast of { norway. epoch of the last great baltic glacier. { . freshwater alluvia (with arctic plants); "lower { buried forest and peat" (britain and north-west { europe generally). carse-clays and raised { beaches of to -feet level in scotland. interglacial { { britain again continental; climate at first { cold, subsequently becoming temperate: great { forests. eventual insulation of britain; climate { humid, and probably colder than now. { . local moraines in mountain-valleys of britain, { here and there resting on to -feet beach; { so-called "post-glacial" moraines in the upper { valleys of the alps. { { probably final appearance of glaciers in our glacial { islands. some of these glaciers attained a { considerable size, reaching the sea and shedding { icebergs. it may be noted here that the decay { of these latest glaciers was again followed by { emergence of the land and a recrudescence of { forest-growth ("upper buried forest"). a word of reference may now be made to that remarkable association of evidence of submergence, with proofs of glacial conditions, which has so frequently been noted by geologists. take, for example, the succession in scotland, and observe how each glacial epoch was preceded and apparently accompanied by partial submergence of the land:-- . _epoch of greatest mer de glace_ (lower boulder-clay); british and scandinavian ice-sheets coalescent. followed by wide land-surface = continental britain, with genial climate. submergence of land--to what extent is uncertain, but apparently to feet or so. . _epoch of lesser mer de glace_ (upper boulder-clay); british and scandinavian ice-sheets coalescent. followed by wide land-surface = continental britain, with genial climate. submergence of land for feet or thereabout. . _epoch of local ice-sheets in mountain districts;_ glaciers here and there coalesce on the low-grounds; icebergs calved at mouths of highland sea-lochs (moraines on -feet beach). followed by wide land-surface = continental britain, with genial climate. submergence of land for feet or thereabout. . _epoch of small local glaciers_, here and there descending to sea (moraines on -feet beach). these oscillations of the sea-level did not terminate with the emergence of the land after the formation of the -feet beach. there is evidence to show that subsequent to the retreat of the small local glaciers ( ) and the emergence of the land, our shores extended seawards beyond their present limits, but how far we cannot tell. with this epoch of re-emergence the climate again became more genial, our forests once more attaining a greater vertical and horizontal range. submergence then followed (the to -feet beach), accompanied by colder and more humid conditions, which, while unfavourable to forest-growth, tended greatly to increase the spread of peat-bogs. we have no evidence, however, to show that small local glaciers again appeared. finally the sea retired, and the present conditions ensued. it will be seen that the submergence which preceded and probably accompanied the advent of the lesser _mer de glace_ ( ) was greater than that which heralded the appearance of the local ice-sheets ( ), as that in turn exceeded the depression that accompanied the latest local glaciers ( ). there would seem, therefore, to be some causal connection between cold climatic conditions and submergence. this is shown by the fact that not only did depression immediately precede and accompany the appearance of ice-sheets and glaciers, but the degree of submergence bore a remarkable relation to the extent of glaciation. many speculations have been indulged in as to the cause of this curious connection between glaciation and depression; these, however, i will not consider here. none of the explanations hitherto advanced is satisfactory, but the question is one well deserving the attention of physicists, and its solution would be of great service to geology. a still larger question which the history of these times suggests is the cause of climatic oscillations. i have maintained that the well-known theory advanced by james croll is the only one that seems to throw any light upon the subject, and the observations which have been made since i discussed the question at length, some fifteen years ago, have added strength to that conviction. as sir robert ball has remarked, the astronomical theory is really much stronger than croll made it out to be. in his recently-published work, _the cause of an ice age_, sir robert says that the theory is so thoroughly well based that there is no longer any ground for doubting its truth. "we have even shown," he continues, "that the astronomical conditions are so definite that astronomers are entitled to direct that vigorous search be instituted on this globe to discover the traces of those vast climatic changes through which astronomy declares that our earth must have passed." in concluding this paper, therefore, i may shortly indicate how far the geological evidence seems to answer the requirements of the theory. following croll, we find that the last period of great eccentricity of the earth's orbit extended over , years--the eccentricity reaching its highest value in the earlier stages of the cycle. it is obvious that during this long cycle the precession of the equinox must have completed seven revolutions. we might therefore expect to meet with geological evidence of recurrent cold or glacial and genial or interglacial epochs; and not only so, but the records ought to show that the earlier glacial epoch or epochs were colder than those that followed. now we find that the epoch of maximum glaciation supervened in early pleistocene times, and that three separate and distinct glacial epochs of diminished severity followed. of these three, the first would appear to have been almost as severe as that which preceded it, and it certainly much surpassed in severity the cold epochs of the later stages. but the epoch of maximum glaciation, or the first of the pleistocene series, was not the earliest glacial epoch. it seems to have been preceded by one of somewhat less severity than itself, but which nevertheless, as we gather from the observations of penck and his collaborators, was about as important as that which came after the epoch of maximum glaciation. hence it would appear that the correspondence of the geological evidence with the requirements of the astronomical theory is as close as we could expect it to be. four glacial with intervening genial epochs appear to have fallen within pleistocene times; while towards the close of the pliocene, or at the beginning of the pleistocene period, according as we choose to classify the deposits, an earlier glacial epoch followed by genial interglacial conditions, supervened. in this outline of a large subject it has not been possible to do more than indicate very briefly the general nature of the evidence upon which the chief conclusions are based. i hope, however, to have an opportunity ere long of dealing with the whole question in detail. [note.--since the original publication of this essay, renewed investigation and study have led me to conclude that the correlation of the british and continental glacial series is even more simple than i had supposed. i believe the use of the terms "lower" and "upper" in connection with the "diluvial" deposits of the continent has hitherto blinded us to the obvious succession of the boulder-clays. in britain we have, as shown above, a "lower boulder-clay," an "upper boulder-clay," and the still younger boulder-clays (ground-moraines), and terminal moraines of our district ice-sheets and valley-glaciers. in the low-grounds of the continent the succession is precisely similar. thus the lower boulder-clay that sweeps south into saxony represents the lower boulder-clay of britain. in like manner, the upper boulder-clay of western and middle germany, of poland, and western and north-western russia, is the equivalent of our own upper boulder-clay. lastly, the so-called "upper diluvium" and the great terminal moraines of the baltic coast-lands are on the horizon of the younger boulder-clays and terminal moraines of the mountainous areas of the british islands. the so-called "lower diluvium" of the baltic coast-lands thus represents not the _lower_ but the _upper_ diluvium of western and middle germany, poland, etc. german geologists are of opinion that the upper boulder-clays of the baltic coast-lands and of the valley of the elbe are the ground-moraines of one and the same ice-sheet, which, on its retreat, piled up the terminal moraines of the baltic ridge. i believe the two boulder-clays in question are quite distinct, and that the terminal moraines referred to mark the furthest advance of the last great baltic glacier. the contemporaneity of the two boulder-clays has been taken for granted simply because they are each underlaid by a lower boulder-clay. but, as we have seen, the upper boulder-clay of the baltic coast-lands is underlaid not by one only, but by two, and in some places even by three other boulder-clays--phenomena which never present themselves in the regions not invaded by the last great baltic glacier. three or four boulder-clays occur in the coast-lands of the baltic because those regions were overflowed successively by three or four separate ice-sheets. only two boulder-clays are met with south and east of the baltic ridge, because the tracts lying south and south-east of that ridge were traversed by only two _mers de glace_--namely, by that of the epoch of maximum glaciation and by the less extensive ice-sheet of the next succeeding cold period. in the region between the elbe and the mountains of middle germany only one boulder-clay appears, because that region has never been invaded by more than one ice-sheet. the succession thus indicated may be tabulated as follows:-- . _epoch of earliest baltic glacier._ lowest boulder-clay of southern sweden; lowest boulder-clay of baltic provinces of prussia; horizon of the weybourn crag. . _epoch of greatest mer de glace._ lower boulder-clays of middle and southern germany, central russia, british islands; second boulder-clay of baltic provinces of prussia. . _epoch of lesser mer de glace._ upper boulder-clay of western and middle germany, poland, and west central russia; upper boulder-clay of britain; third boulder-clay of baltic provinces of prussia. . _epoch of last great baltic glacier._ upper boulder-clay and terminal moraines of baltic coast-lands; district and valley-moraines of highlands and uplands of british islands. . _epoch of small local glaciers._ valley-moraines in mountainous regions of britain, etc. the evidence on which these conclusions are based is set forth at some length in a forthcoming re-issue of my _great ice age_.--nov. , .] [illustration: plate iv sketch map of northern europe showing areas covered by ice during the epoch of maximum glaciation, and by the great baltic glacier and the local ice-sheets of britain at a later date. the edinburgh geographical institute j. g. bartholomew f.r.g.s ] * * * * * explanation of plate iv. map of europe showing the areas occupied by ice during the epoch of maximum glaciation (second glacial epoch), and the extent of glaciation in scandinavia, finland, baltic coast-lands, etc., and the british islands during the fourth glacial epoch. for the limits of the greater glaciation on the continent, habenicht, penck, nikitin, and nathorst have been followed. the great baltic glacier is chiefly after de geer. xi. the geographical evolution of europe.[df] [df] _the scottish geographical magazine_, vol. ii., . it is one of the commonplaces of geology that the present is built up out of the ruins of the past. every rock beneath our feet has its story of change to tell us. mountains, valleys, and plains, continents and islands, have passed through vicissitudes innumerable, and bear within them the evidence of a gradual development or evolution. looking back through the vista of the past one sees the dry lands gradually separating from the ocean, and gathering together into continental masses according to a definite plan. it is this slow growth, this august evolution, carried on through countless æons, which most impresses the student of physical geology. the earth seems for the time as if endowed with life, and like a plant or animal to pass through its successive stages of development until it culminates in the present beautiful world. this conception is one of comparatively recent growth in the history of geological science. hutton, the father of physical geology, had indeed clearly perceived that the dry lands of the globe were largely composed of the débris of former land-surfaces--that there had been alternate elevations and depressions of the earth's crust, causing now sea and now land to predominate over given areas. but the facts known in this day could not possibly have suggested those modern ideas of geographical evolution, which are the outcome of the multifarious observation and research of later years. it is to professor dana, the eminent american geologist, that we are indebted for the first clear enunciation of the views which i am now about to illustrate. according to him the great oceanic basins and continental ridges are of primeval antiquity--their origin is older than that of our oldest sedimentary formations. it is not maintained that the present lands have always continued above the level of the sea. on the contrary, it can be proved that many oscillations of level have taken place within each continental area, by which the extent and outline of the land have been modified again and again. notwithstanding such changes, however, the great continental ridges would appear to have persisted from the earliest geological times as dominant elevations of the earth's crust. some portions of these, as dana remarks, may have been submerged for thousands of feet, but the continents have never changed places with the oceans. i shall presently indicate the nature of the evidence by which it is sought to prove the vast age of our continental masses, but before doing so it will be well to give an outline of the facts which go to show that the oceanic depressions of the globe are likewise of primeval antiquity. the memorable voyage of the _challenger_ has done much to increase our knowledge of the deep seas and the accumulations forming therein. the researches of the scientific staff of the expedition, and more particularly those of mr. murray, have indeed given a new impulse to the study of the larger questions of physical geology, and have lent strong support to the doctrine of the permanence of the oceanic basins and continental ridges. one of the most important facts brought before our attention by mr. murray is the absence of any land-derived materials from the sediments now gathering in the deeper abysses of the ocean. the coasts of continents and continental islands are strewn, as every one knows, with the wreck of the land--with gravel, sand, and mud, derived from the demolition of our rocks and soils. the coarser débris accumulates upon beaches and in shallow littoral waters, while the finer materials are swept further out to sea by tidal and other currents--the sediment being gradually sifted as it is borne outwards into deeper water, until only the finest mud and silt remain to be swept forward. as the floor of the ocean shelves down to greater depths the transporting power of currents gradually lessens, and finally land-derived sediment ceases to appear. such terrigenous materials may be said to extend from the littoral zone down to depths of feet and more, and to a distance of to miles from shore. they are confined, therefore, to a comparatively narrow belt round the margins of continents and islands. and thus there are vast regions of the oceanic depressions over which no terrigenous or land-derived materials are accumulating. instead of these we meet with a remarkable red clay and various kinds of ooze, made up largely of the shells of foraminifera, pelagic mollusca, and radiolarians, and the frustules of diatoms. the red clay is the most widely distributed of abysmal deposits. indeed, it seems to form a certain proportion of all the deep-sea organic oozes, and may be said, therefore, to exist everywhere in the abysmal regions of the oceanic basins. it is extremely fine-grained, and owes its deep brown or red colour to the presence of the oxides of manganese and iron. scattered through the deposit occur particles of various minerals of volcanic origin, together with lapilli and fragments of pumice, _i.e._, volcanic _ejectamenta_. such materials may have been thrown out from terrestrial volcanoes and carried by the winds or floated by currents until they became water-logged and sank; or they may to some extent be the relics of submarine eruptions. whatever may have been their immediate source, they are unquestionably of volcanic origin, and are not associated with any truly terrigenous sediment. the red clay is evidently the result of the chemical action of sea-water on volcanic products; and many facts conspire to show that its formation is an extremely slow process. thus, remains of vertebrates, consisting of the ear-bones of whales, beaks of ziphius, and teeth of sharks, are often plentifully present, and there is no reason to suppose, as mm. murray and renard point out, that the parts of the ocean where these remains occur are more frequented by whales and sharks than other regions where similar relics are rarely or never dredged up. of these remains some have all the appearance of having lain upon the sea-bottom for a very long time, for they belong to extinct species, and are either partially coated or entirely surrounded with thick layers of manganese-iron. in the same red clay occur small metallic spherules which are of cosmic origin--in other words, meteoric dust. the accumulation of all these substances in such relatively great abundance shows us that the oceanic basins have remained unchanged for a vast period of time, and assures us that the formation of the abysmal red clay is extremely slow. when we come to examine the rocks which enter into the framework of our continents, we find that they may be roughly classed under these heads:-- st, terrestrial and aqueous rocks. d, igneous rocks. d, crystalline schists. by far the largest areas of land are composed of rocks belonging to the first class. these consist chiefly of the more or less indurated sediments of ancient rivers, lakes, and seas--namely, conglomerate, sandstone, shale, limestone, etc. and now and again, interstratified with such aqueous beds, we meet with rocks of terrestrial origin, such as lignite, coal, and the débris of former glacial action. now, most of our aqueous rocks have been accumulated in the sea, and thus we arrive at the conclusion that the present continental areas have from time to time been largely submerged--that the sea has frequently covered what are now the dry lands of the globe. but one remarkable fact stands out, and it is this: nowhere amongst the sedimentary rocks of the earth's crust do we meet with any ancient sediments which can be likened to the red clay now slowly accumulating in the deeper abysses of the ocean. there are no rocks of abysmal origin. many of our limestones have undoubtedly formed in deep, clear water, but none of these is abysmal. portions of europe may now and again have been submerged for several thousand feet, but no part of this or any other continent, so far as we yet know, has within geological time been depressed to depths comparable to those of the present oceanic basins. nay, by far the larger portions of our marine formations have accumulated in comparatively shallow water--sandstones and shales (sand and mud) being by far the most common kinds of rock that we encounter. in short, aqueous strata have, as a rule, been deposited at no great depth and at no great distance from dry land; the rocks are built up mostly of terrigenous material; and even the purer limestones and chalks, which we may suppose accumulated in seas of moderate depth, not infrequently contain some terrestrial relic which has been drifted out to sea, and afford other evidence to show that the nearest land was never very far away. followed along their outcrop such rocks sooner or later become mixed and interbedded with ordinary sedimentary matter. thus, for example, the thick carboniferous limestone of wales and the midlands of england must have accumulated in the clear water of a moderately deep sea. but when this limestone is traced north into northumberland it begins to receive intercalations of sandstone and shale, which become more and more important, until in scotland they form by much the larger portion of the series--the enormous thick limestones of the south being represented by only a few inconsiderable beds, included, along with seams of ironstone and coal, in a thick succession of sandstones and shales. of the igneous rocks and the crystalline schists i need not speak at present, but i shall have something to say about them before i have done. having learned that no truly abysmal rocks enter into the composition of our continents, of what kind of rocks, we may ask, are the islands composed? well, some of those islands are built up of precisely the same materials as we find in the continents. this is the case with most islands which are not separated from continental areas by profoundly deep seas. thus our own islands with their numerous satellites are geologically one with the adjacent continent. their present separation is a mere accident. were the european area, with the adjacent sea-bed, to be elevated for a few hundred feet we should find that britain and ireland form geologically part and parcel of the continent. and the same is the case with nova zembla and spitzbergen in the north, and with the mediterranean islands in the south. there is another large class of islands, however, which are characterised by the total absence of any of those sedimentary rocks of which, as i have just said, our continents and continental islands are chiefly built up. the islands referred to are scattered over the bosom of the great ocean, and are surrounded by profoundly deep water. some are apparently composed entirely of coral, others are of volcanic origin, and yet others are formed partly of volcanic rock and partly of coral. thus we have two distinct kinds of island:-- st, islands which have at one time evidently been connected with adjacent continents, and which are therefore termed _continental islands_; and d, _oceanic islands_, which rise, as it were, from profound depths in the sea, and which have never formed part of the continents. the fauna and flora of the former class agree with those of the neighbouring continents, although some modifications are met with, especially when the insulation has been of long standing. when such has been the case the species of plants and animals may be almost entirely distinct. nevertheless, such ancient continental islands agree with those which have been separated in more recent geological times in containing both indigenous amphibians and mammals. oceanic islands, on the other hand, contain no indigenous mammals or amphibians, their life consisting chiefly of insects and birds, and usually some reptiles--just such a fauna as might have been introduced by the influence of winds and of oceanic currents carrying driftwood. such facts, as have now been briefly summarised, point clearly to the conclusion that the oceanic basins and continental areas are of primeval antiquity. all the geological facts go to prove that abysmal waters have never prevailed over the regions now occupied by dry land; nor is there any evidence to show that continental land-masses ever existed in what are now the deepest portions of the ocean. the islets dotted over the surface of the pacific and the other great seas are not the relics of a vast submerged continent. they are either the tops of submarine volcanic mountains, or they are coral structures founded upon the shoulders of degraded volcanoes and mountain-chains, and built up to the surface by the indefatigable labours of the humble polyp. we come then to the general conclusion that oceanic basins and intervening continental ridges are great primeval wrinkles in the earth's crust--that they are due to the sinking down of that crust upon the cooling and contracting nucleus. these vast wrinkles had come into existence long before the formation of our oldest geological strata. all our rocks may, in short, be looked upon as forming a mere superficial skin covering and concealing the crystalline materials which no doubt formed the original surface of the earth's crust. having premised so much, let me now turn to consider the geological history of our own continent, and endeavour to trace out the various stages in its evolution. of course i can only do so in a very brief and general manner; it is impossible to go into details. we shall find, however, that the history of the evolution of europe, even when sketched in outline, is one full of instruction for students of physical geography, and that it amply bears out the view of the permanency of the greater features of the earth's surface. the oldest rocks that we know of are the crystalline schists and gneiss, belonging to what is called the archæan system. the origin of these rocks is still a matter of controversy--some holding them to be part of the primeval crust of the globe, or the chemical precipitates of a primeval ocean, others maintaining that they are altered or metamorphosed rocks of diverse origin, a large proportion having consisted originally of aqueous or sedimentary rocks, such as sandstone and shale; while not a few are supposed to have been originally eruptive igneous rocks. according to some geologists, therefore, the archæan rocks represent the earliest sediments deposited over the continental ridges. it is supposed that here and there those ridges rose above the surface of what may have been a boiling or highly-heated ocean, from whose waters copious chemical precipitations took place, while gravel and shingle gathered around the shores of the primeval lands. according to other writers, however, the archæan rocks were probably accumulated under normal conditions. they consist, it is contended, partly of sediment washed down from some ancient land-surface, and distributed over the floor of an old sea (just as sediments are being transported and deposited in our own day), and partly of ancient igneous rocks. their present character is attributed to subsequent changes, superinduced by heat and pressure, at a time when the masses in question were deeply buried under later formations, which have since been washed away. in a word, we are still quite uncertain as to the true origin of the archæan rocks. not infrequently they show a bedded structure, and in that respect they simulate the appearance of strata of sedimentary origin. it is very doubtful, however, whether this "bedded structure" is any evidence of an original aqueous arrangement. we know now that an appearance of bedding has been induced in originally amorphous rocks during great earth-movements. granite masses, for example, have been so crushed and squeezed as to assume a bedded aspect, and a similar structure has been developed in many other kinds of rock subjected to enormous pressure. whatever may have been the origin of the bedded structure of the archæan rocks, it is certain that the masses have been tilted up and convoluted in the most remarkable manner. hitherto they have yielded no unequivocal trace of organic remains--the famous _eozoon_ being now generally considered as of purely mineral origin. the physical conditions under which the archæan gneiss and schist came into existence are thus quite undetermined, but geologists are agreed that the earliest land-surfaces, of the former existence of which we can be quite certain, were composed of rocks. and this brings us to the beginning of reliable geological history. all subsequent geological time--that, namely, of which we have any record preserved in the fossiliferous strata--is divided into four great eras, namely the palæozoic, the mesozoic, the cainozoic, and the post-tertiary eras, each of which embraces various periods, as follows:-- post-tertiary {recent. {pleistocene. {pliocene. tertiary or {miocene. cainozoic {oligocene. {eocene. {cretaceous. secondary or {jurassic. mesozoic {triassic. {permian. {carboniferous. primary or {devonian and old red sandstone. palæozoic {silurian. {cambrian. archæan, fundamental gneiss. leaving the archæan, we find that the next oldest strata are those which were accumulated during the cambrian period, to which succeeded the silurian, the devonian and old red sandstone, the carboniferous, and the permian periods--all represented by great thicknesses of strata, which overspread wide regions. now, at the beginning of the cambrian period, we have evidence to show that the primeval continental ridge was still largely under water, the dry land being massed chiefly in the north. at that distant date a broad land-surface extended from the outer hebrides north-eastwards through scandinavia, finland, and northern russia. how much further north and north-west of the present limits of europe that ancient land may have extended we cannot tell, but it probably occupied wide regions which are now submerged in the shallow waters of the arctic ocean. in the north of scotland a large inland sea or lake existed in cambrian times,[dg] and there is some evidence to suggest that similar lacustrine conditions may have obtained in the welsh area at the beginning of the period. south of the northern land lay a shallow sea covering all middle and southern europe. that sea, however, was dotted here and there with a few islands of archæan rocks, occupying the site of what are now some of the hills of middle germany, such as the riesen gebirge, the erz gebirge, the fichtel gebirge, etc., and possibly some of the archæan districts of france and the iberian peninsula. [dg] the red sandstones of the north-west highlands are now believed to be of pre-cambrian age. the succeeding period was one of eminently marine conditions, the wide distribution of silurian strata showing that during the accumulation of these, enormous tracts of our continent were overflowed by the sea. none of these deposits, however, is of truly oceanic origin. they appear for the most part to have been laid down in shallow seas, which here and there may have been moderately deep. during the formation of the lower silurian the whole of the british area, with the exception perhaps of some of the archæan tracts of the north-west, seems to have been under water. the submergence had commenced in cambrian times, and was continued up to the close of the lower silurian period. during this long-continued period of submergence volcanic activity manifested itself at various points--our country being represented at that time by groups of volcanic islands, scattered over the site of what is now wales, and extending westward into the irish region, and northwards into the districts of cumberland and south ayrshire. towards the close of the lower silurian period considerable earth-movements took place, which had the effect of increasing the amount of dry land, the most continuous mass or masses of which still occupied the northern and north-western part of our continent. in the beginning of upper silurian times a broad sea covered the major portion of middle and probably all southern europe. numerous islands, however, would seem to have existed in such regions as wales, and the various tracts of older palæozoic and archæan rocks of middle germany. many of these islands, however, were partially and some entirely submerged before the close of silurian times. the next great period--that, namely, which witnessed the accumulation of the devonian and old red sandstone strata--was in some respects strongly contrasted to the preceding period. the silurian rocks, as i have said, are eminently marine. the old red sandstones, on the other hand, appear to have been accumulated chiefly in great lakes or inland seas, and they betoken therefore the former existence of extensive lands, while the contemporaneous devonian strata are of marine origin. towards the close of the upper silurian period, then, we know that considerable upheavals ensued in western and north-western europe, and wide stretches of the silurian sea-bottom were converted into dry land. the geographical distribution of the devonian in europe, and the relation of that system to the silurian, show that the devonian sea did not cover so broad an expanse as that of the upper silurian. the sea had shallowed, and the area of dry land had increased when the devonian strata began to accumulate. in trying to realise the conditions that obtained during the formation of the devonian and the old red sandstone, we may picture to ourselves a time when the atlantic ocean extended eastwards over the south of england and the north-east of france, and occupied the major portion of central europe, sweeping north-east into russia, and how much further we cannot tell. north of that sea stretched a wide land-surface, in the hollows of which lay great lakes or inland seas, which seem now and again to have had communication with the open ocean. it was in these lakes that the old red sandstone was accumulated, while the devonian or marine rocks were formed in the wide waters lying to the south. submarine volcanoes were active at that time in germany; and similarly in scotland numerous volcanoes existed, such as those of the sidlaw hills and the cheviots. the carboniferous system contains the record of a long and complex series of geographical changes, but the chief points of importance in the present rapid review may be very briefly summed up. in the earlier part of the period marine conditions prevailed. thus we find evidence to show that the sea extended further north than it did during the preceding devonian period. during the formation of the mountain-limestone, a deep sea covered the major portion of ireland and england, but shallowed off as it entered the scottish area. a few rocky islets were all that represented ireland and england at that time. passing eastwards, the carboniferous sea appears to have covered the low-grounds of middle europe and enormous tracts in russia. the deepest part of the sea lay over the anglo-hibernian and franco-belgian areas; towards the east it became shallower. probably the same sea swept over all southern europe, but many islands may have diversified its surface, as in brittany and central france, in spain and portugal, and in the various areas of older palæozoic and archæan rocks in central and south-west europe. in the latter stages of the carboniferous period, the limits of the sea were much circumscribed, and wide continental conditions supervened. enormous marshes, jungles, and forests now overspread the newly-formed lands. another feature of the carboniferous was the great number of volcanoes--submarine and sub-aërial--which were particularly abundant in scotland, especially during the earlier stages of the period. the rocks of the permian period seem to have been deposited chiefly in closed basins. when, owing to the movement of elevation or upheaval which took place in late carboniferous times, the carboniferous limestone sea had been drained away from extensive areas in central europe, wide stretches of sea still covered certain considerable tracts. these, however, as time went on, were cut off from the main ocean and converted into great salt lakes. such inland seas overspread much of the low-lying tracts of britain and middle germany, and they also extended over a broad space in the north-east of russia. it was in these seas that the permian strata were accumulated. the period, it may be added, was marked by the appearance of volcanic action in scotland and germany. so far, then, as our present knowledge goes, that part of the european continent which was the earliest to be evolved lay towards the north-west and north. all through the palæozoic era a land-surface would seem to have endured in that direction--a land-surface from the denudation or wearing down of which the marine sedimentary formations of the bordering regions were derived. but when we reflect on the great thickness and horizontal extent of those sediments, we can hardly doubt that the primeval land must have had a much wider range towards the north and north-west than is the case with modern europe. the lands, from which the older palæozoic marine sediments of the british islands and scandinavia were obtained, must, for the most part, be now submerged. in later palæozoic times land began to extend in the spanish peninsula, northern france, and middle europe, the denudation of which doubtless furnished materials for the elaboration of the contemporaneous strata of those regions. southern europe is so largely composed of mesozoic and cainozoic rocks that we can say very little as to the condition of that area in palæozoic times, but the probabilities are that it continued for the most part under marine conditions. in few words, then, we may conclude that while after archæan times dry land prevailed in the north and north-west, marine conditions predominated further south. ever and anon, however, the sea vanished from wide regions in central europe, and was replaced by terrestrial and lacustrine conditions. further, as none of the palæozoic marine strata indicates a deep ocean, but all consist for the most part of accumulations formed at moderate depths, it follows that there must have been a general subsidence of our area to allow of their successive deposition--a subsidence, however, which was frequently interrupted by long pauses, and sometimes by movements in the opposite direction. the first period of the mesozoic era, namely, the triassic, was characterised by much the same kind of conditions as obtained towards the close of palæozoic times. a large inland sea then covered a considerable portion of england, and seems to have extended north into the south of scotland, and across the area of the irish sea into the north-east of ireland. another inland sea extended westward from the thüringer-wald across the vosges into france, and stretched northwards from the confines of switzerland over what are now the low-grounds of holland and northern germany. in this ancient sea the harz mountains formed a rocky island. while terrestrial and lacustrine conditions thus obtained in central and northern europe, an open sea existed in the more southerly regions of the continent. towards the close of the period submergence ensued in the english and german areas, and the salt lakes became connected with the open sea. during the jurassic period the regions now occupied in britain and ireland by the older rocks appear to have been chiefly dry land. scotland and ireland, for the most part, stood above the sea-level, while nearly all england was under water--the hills of cumberland and westmoreland, the pennine chain, wales, the heights of devon and cornwall, and a ridge of palæozoic rocks which underlies london, being the chief lands in south britain. the same sea overflowed an extensive portion of what is now the continent. the older rocks in the north-west and north-east of france, and the central plateau of the same country, formed dry land; all the rest of that country was submerged. in like manner the sea covered much of eastern spain. in middle europe it overflowed nearly all the low-grounds of north germany, and extended far east into the heart of russia. it occupied the site of the jura mountains, and passed eastward into bohemia, while on the south side of the alps it spread over a large part of italy, extending eastward so as to submerge a broad area in austria-hungary and the turkish provinces. thus the northern latitudes of europe continued to be the site of the chief land-masses, what are now the central and southern portions of the continent being a great archipelago with numerous islands, large and small. the jurassic rocks, attaining as they do a thickness of several thousand feet, point to very considerable subsidence. the movement, however, was not continuous, but ever and anon was interrupted by pauses. taken as a whole, the strata appear to have accumulated in a comparatively shallow sea, which, however, was sufficiently deep in places to allow of the growth, in clear water, of coral-reefs. towards the close of the jurassic period a movement of elevation ensued, which caused the sea to retreat from wide areas, and thus when the cretaceous period began the british region was chiefly dry land. middle europe would seem also to have participated in this upward movement. eventually, however, subsidence again ensued. most of what are now the low-grounds of britain were submerged, the sea stretching eastwards over a vast region in middle europe, as far as the slopes of the urals. the deepest part of this sea, however, was in the west, and lay over england and northern france. further east, in what are now saxony and bohemia, the waters were shallow, and gradually became silted up. in the mediterranean basin a wide open sea existed, covering large sections of eastern spain and southern france, overflowing the site of the jura mountains, drowning most of the alpine lands, the italian peninsula, the eastern borders of the adriatic, and greece. in short, there are good grounds for believing that the cretaceous mediterranean was not only much broader than the present sea, but that it extended into asia, overwhelming vast regions there, and communicated with the indian ocean. summing up what we know of the principal geographical changes that took place during the mesozoic era, we are impressed with the fact that, all through those changes, a wide land-surface persisted in the north and north-west of the european area, just as was the case in palæozoic times. the highest grounds were the urals and the uplands of scandinavia and britain. in middle europe the pyrenees and the alps were as yet inconsiderable heights, the loftiest lands being those of the harz, the riesen gebirge, and other regions of palæozoic and archæan rocks. the lower parts of england and the great plains of central europe were sometimes submerged in the waters of a more or less continuous sea; but ever and anon elevation ensued, and the sea was divided, as it were, into a series of great lakes. in the south of europe a mediterranean sea would appear to have endured all through the mesozoic era--a mediterranean of considerably greater extent, however, than the present. thus we see the main features of our continent were already clearly outlined before the close of the cretaceous period. the continental area then, as now, consisted of a wide belt of high-ground in the north, extending roughly from south-west to north-east; south of this a vast stretch of low-grounds, sweeping from west to east up to the foot of the urals, and bounded on the south by an irregular zone of elevated land having approximately the same trend; still further south, the maritime tracts of the mediterranean basin. during periods of depression the low-grounds of central europe were invaded by the sea, and the mediterranean at the same time extended north over many regions which are now dry land. it is in these two low-lying tracts, therefore, and the country immediately adjoining them, that the mesozoic strata of europe are chiefly developed. a general movement of upheaval[dh] supervened at the close of the cretaceous period, and the sea which, during that period, overflowed so much of middle europe had largely disappeared before the beginning of eocene times. the southern portions of the continent, however, were still mostly under water, while great bays and arms of the sea extended northwards now and again into central europe. on to the close of the miocene period, indeed, southern and south-eastern europe consisted of a series of irregular straggling islands and peninsulas washed by the waters of a genial sea. towards the close of early cainozoic times, the alps, which had hitherto been of small importance, were greatly upheaved, as were also the pyrenees and the carpathians. the floor of the eocene sea in the alpine region was ridged up for many thousands of feet, its deposits being folded, twisted, inverted, and metamorphosed. another great elevation of the same area was effected after the miocene period, the accumulations of that period now forming considerable mountains along the northern flanks of the alpine chain. notwithstanding these gigantic elevations in south-central europe--perhaps in consequence of them--the low-lying tracts of what is now southern europe continued to be largely submerged, and even the middle regions of the continent were now and again occupied by broad lakes which sometimes communicated with the sea. in miocene times, for example, an arm of the mediterranean extended up the rhone valley, and stretched across the north of switzerland to the basin of the danube. after the elevation of the miocene strata these inland stretches of sea disappeared, but the mediterranean still overflowed wider areas in southern europe than it does in our day. eventually, however, in late pliocene times, the bed of that sea experienced considerable elevation, newer pliocene strata occurring in sicily up to a height of feet at least. it was probably at or about that period that the black sea and the sea of asov retreated from the wide low-grounds of southern russia, and that the inland seas and lakes of austria-hungary finally vanished. [dh] i now doubt whether any vertical upheaval of a wide continental area is possible. the so-called "continental uplifts" are probably in most cases rather negative than positive elevations. in other words, the land seems to rise simply because the sea retreats owing perhaps to the sinking of the crust within the great oceanic basins. see on this subject, article xiii. the cainozoic era is distinguished in europe for its volcanic phenomena. the grandest eruptions were those of oligocene times. to that date belong the basalts of antrim, mull, skye, the faröe islands, and the older series of volcanic rocks in iceland. these basalts speak to us of prodigious fissure eruptions, when molten rock welled up along the lines of great cracks in the earth's crust, flooding wide regions, and building up enormous plateaux, of which we now behold the merest fragments. the ancient volcanoes of central france, those of the eifel country and many other places in germany, and the volcanic rocks of hungary, are all of cainozoic age; while, in the south of europe, etna, vesuvius, and other italian volcanoes date their origin to the later stages of the same great era. thus before the beginning of pleistocene times all the main features of europe had come into existence. since the close of the pliocene period there have been many great revolutions of climate; several very considerable oscillations of the sea-level have taken place, and the land has been subjected to powerful and long-continued erosion. but the greater contours of the surface which began to appear in palæozoic times, and which in mesozoic times were more strongly pronounced, had been fully evolved by the close of the pliocene period. the most remarkable geographical changes which have taken place since then have been successive elevations and depressions, in consequence of which the area of our continent has been alternately increased and diminished. at a time well within the human period our own islands have been united to themselves and the continent, and the dry land has extended north-west and north, so as to include spitzbergen, the faröe islands, and perhaps iceland. on the other hand, our islands have been within a recent period largely submerged. the general conclusion, then, to which we are led by a review of the greater geographical changes through which the european continent has passed is simply this--that the substructure upon which all our sedimentary strata repose is of primeval antiquity. our dry lands are built up of rocks which have been accumulated over the surface of a great wrinkle of the earth's crust. there have been endless movements of elevation and depression, causing minor deformations, as it were, of that wrinkle, and inducing constant changes in the distribution of land and water; but no part of the continental ridge has ever been depressed to an abysmal depth. the ridge has endured through all geological time. we can see also that the land has been evolved according to a definite plan. certain marked features begin to appear very early in palæozoic times, and become more and more pronounced as the ages roll on. all the countless oscillations of level, all the myriad changes in the distribution of land and water, all the earthquake disturbances and volcanic eruptions--in a word, all the complex mutations to which the geological record bears witness--have had for their end the completion of one grand design. a study of the geological structure of europe--an examination of the manner in which the highly folded and disturbed strata are developed--throws no small light upon the origin of the larger or dominant features of our continent. the most highly convoluted rocks are those of archæan and palæozoic age, and these are developed chiefly in the north-western and western parts of the continent. highly contorted strata likewise appear in all the mountain-chains of central europe--some of the rocks being of palæozoic, while others are of mesozoic and of cainozoic age. leaving these mountains for the moment out of account, we find that it is along the western and north-western sea-board where we encounter the widest regions of highly-disturbed rocks. the highlands of scandinavia and britain are composed, for the most part, of highly-flexed and convoluted rocks, which speak to titanic movements of the crust; and similar much-crushed and tilted rock-masses occur in north-west france, in portugal, and in western spain. but when we follow the highly-folded palæozoic strata of scandinavia into the low-grounds of the great plains, they gradually flatten out, until in russia they occur in undisturbed horizontal positions. over thousands of square miles in that country the palæozoic rocks are just as little altered and disturbed as strata pertaining to mesozoic and cainozoic times. these facts can have but one meaning. could we smooth out all the puckerings, creases, foldings, and flexures which characterise the archæan and palæozoic rocks of western and north-western europe, it is certain that these strata would stretch for many miles out into the atlantic. obviously they have been compressed and crumpled up by some force acting upon them from the west. now, if it be true that the basin of the atlantic is of primeval origin, then it is obvious that the sinking down of the crust within that area would exert enormous pressure upon the borders of our continental area. as cooling and contracting of the nucleus continued, subsidence would go on under the oceanic basin, depression taking place either slowly and gradually, during protracted periods, or now and again more or less suddenly. but whether gradually or suddenly effected, the result of the subsidence would be the same upon the borders of our continent; the strata along the whole western and north-western margins of the european ridge would necessarily be flexed and disturbed. away to the east, however, the strata, not being subject to the like pressure, would be left in their original horizontal positions. now it can be shown that the mountains of scandinavia and the british islands are much older than the alps, the pyrenees, and many other conspicuous ranges in central and southern europe. our mountains and those of scandinavia are the mere wrecks of their former selves. originally they may have rivaled--they probably exceeded--the alps in height and extent. it is most likely, indeed, that the areas of palæozoic rocks in france, portugal, and spain also attained mountainous elevations. but the principal upheaval of the western margins of our continent was practically completed before the close of the palæozoic period, and since that time those elevated regions have been subjected to prodigious erosion, the later formations being in large measure composed of their débris. i do not, of course, wish it to be understood that there has been no upheaval affecting the west of europe since palæozoic times. the tilted position of many of our mesozoic strata clearly proves the contrary. but undoubtedly the main disturbances which produced the folding, fracturing, and contortion of the palæozoic strata of western europe took place before the close of the palæozoic period. the mountains of britain and scandinavia are amongst the oldest in europe. when we come to inquire into the origin of the mountains of central europe we have little difficulty in detecting the chief factors in their formation. an examination of the pyrenees, the alps, and other hill-ranges having the same general trend shows us that they consist of flexed and convoluted rocks. they are, in short, mountains of elevation, ridged up by tangential thrusts. of this we need not have the slightest doubt. if, for example, we approach the alps from the low-grounds of france, we observe the strata as we come towards the jura beginning to undulate--the undulations becoming more and more marked, and passing into sharp folds and plications, until, in the alps, the beds become twisted, convoluted, and bent back upon themselves in the wildest confusion. now, speaking in general terms, we may say that similar facts confront us in connection with every true mountain-range in central europe. let it be noted, further, that all those ranges have the same trend, which we may take to be approximately east and west, or nearly at right angles to the trend of the palæozoic high-grounds of western and north-western europe. looked at broadly, our continental ridge may be said to be traversed from west to east by two wide depressions or troughs, separated by the intervening belt of higher grounds just referred to. the former of these troughs corresponds to the great central plain, which passes through the south of england, north-east france, the low countries, and denmark, whence it sweeps east through germany, and expands into the wide low-grounds of russia. the southern trough or depression embraces the maritime tracts of the mediterranean and the regions which that sea covers. such, then, are the dominant features of our continent, to which all others are of subordinate importance. now it cannot be doubted that the two great troughs are belts of subsidence in the continental ridge itself. and their existence explains the origin of the mountain-ranges which separate them. we know that the northern trough is of extreme antiquity; it is older, at all events, than the silurian period. even at that distant date its southern limits were marked out by ridges of archæan rocks, which seem to have formed islands in what is now middle germany, and probably also in switzerland and central france. the appearance of those archæan rocks in central europe was doubtless due to a ridging up of the crust induced by those parallel movements of subsidence which produced the northern and southern troughs. the northern trough was probably always the shallower depression of the two, for we have evidence to show that, again and again in mesozoic and later times, the seas which overflowed what are now the central plains of europe were of less considerable depth than that which occupied the mediterranean trough. as time rolled on, therefore, the northern trough eventually became silted up; but so low even now is the level of that trough that a relatively slight depression would cause the sea to inundate most extensive regions in middle europe. in cainozoic times, as we have seen, the last great elevation of the alps was effected--an elevation which can hardly have been due to any other cause than the more or less abrupt depression of the earth's crust under the mediterranean basin. the area of that sea is now much less considerable than it was in tertiary times--a change due in part to silting up, but chiefly perhaps to the sinking down of its bed to profounder depths. thus we may conclude that from a very early period--a period ante-dating the formation of our oldest fossiliferous strata--the physical structure of our continent had already been planned. the dominant features of the primeval continental ridge are those which have endured through all geological time. they are the lines along which the beautiful lands in which we dwell have been constructed. tilted and convoluted, broken and crushed by myriad earth-movements--scarred, furrowed, worn and degraded by the frosts, the rains, the rivers, and the seas of countless ages--the rocks of our continent are yet eloquent of design. where the ignorant sees nothing save confusion and discord, the thoughtful student beholds everywhere the evidence of a well-ordered evolution. such is the conclusion to which we are led by all geological research. [illustration: sketch-maps illustrating the geographical evolution of continental areas by professor james geikie, ll.d., d.c.l., f.r.s. plate v +-----------------------------+------------------------------+ | map showing the | map showing the | | area of continental plateau | area of continental plateau | | occupied by sea in | occupied by sea in | | palÆozoic times. | tertiary times. | +-----------------------------+------------------------------+ | map showing the | map showing the | | area of continental plateau | areas of dominant depression | | occupied by sea in | and elevation. | | mesozoic times. | (below & above the | | | fathom contour line) | +-----------------------------+------------------------------+ the edinburgh geographic institute j. g. bartholomew, f.r.g.s. ] xii. the evolution of climate.[di] [di] address delivered before the royal physical society at the opening of the session - . one of the most interesting questions with which geological science has to deal is that of the evolution of climate. although there is no general agreement as to how former climatic fluctuations came about, yet the prevalent opinion is that in the past, just as in the present, the character of the climate must have depended mainly on latitude and the relative position of the great land- and water-areas. this was the doctrine taught by lyell, and its cogency none will venture to dispute. it is true he postulated a total redistribution of oceans and continents--a view which the progress of science has shown to be untenable. we can no longer speculate with him on the possibility of all the great land-areas having been grouped at one time round the equator, and at some other period about the poles. on the contrary, the evidence goes to show that the continents have never changed places with the ocean--that the dominant features of the earth's crust are of primeval antiquity, and ante-date the oldest of the fossiliferous formations. the whole question of climatic changes, therefore, must be reconsidered from the point of view of the modern doctrine of the permanency of continental and oceanic areas. but before proceeding to this discussion, it may be well to glance for a moment at the evidence from which it has been inferred that the climate of the world has varied. among the chief proofs of climatic fluctuations are the character and the distribution of former floras and faunas. it is true, fossils are, for the most part, relics of extinct forms, and we cannot assert of any one of these that its environment must have been the same as that of some analogous living type. but, although we can base no argument on individual extinct forms, it does not follow that we are precluded from judging of the conditions under which a whole suite of extinct organisms may have lived. doubtless, we can only reason from the analogy of the present; but, when we take into account all the forms met with in some particular geological system, we seem justified in drawing certain conclusions as to the conditions under which they flourished. thus, should we encounter in some great series of strata many reef-building corals, associated with large cephalopods and the remains of tree-ferns and cycads, which last from their perfect state of preservation could not have drifted far before they became buried in sediment, we should surely be entitled to conclude that the strata in question had been deposited in the waters of a genial sea, and that the neighbouring land likewise enjoyed a warm climate. again should a certain system, characterised by the presence of some particular and well-marked flora and fauna, be encountered not only in sub-tropical and temperate latitudes but also far within the arctic circle, we should infer that such a flora and fauna lived under climatic conditions of a very different kind from any that now exist. the very presence, in the far north, of fossils having such a geographical distribution would show that the temperature of polar seas and lands could not have been less than temperate. when such broad methods of interpretation are applied to the problems suggested by former floras and faunas, we seem compelled to conclude that the conditions which determined the distribution of life in bygone ages must have been, upon the whole, more uniform and equable than they are now. it is unnecessary that i should go into detailed proof; but i may refer, by way of illustration, to what is known of the silurian and carboniferous fossils of the arctic regions. most of these occur also in the temperate latitudes of europe and north america, while many are recognised as distinctive types of the same strata nearly all the world over. as showing how strongly the former broad distribution of life-forms is contrasted with their present restricted range, professor heilprin has cited the brachiopoda. taking existing species and varieties as being in number, he remarks that "there is scarcely a single species which can be said to be strictly cosmopolitan in its range, although not a few are very widely distributed; and, if we except boreal and hyperboreal forms, but a very limited number whose range embraces opposite sides of the same ocean. on the other hand, if we accept the data furnished by richthofen concerning the chinese brachiopoda we find that out of a total of thirteen silurian and twenty-four devonian species, no less than ten of the former and sixteen of the latter recur in the equivalent deposits of western europe: and, further, that the devonian species furnish eleven, or nearly per cent. of the entire number, which are cosmopolitan or nearly so. again, of the twenty-five carboniferous species, north america holds fully fifteen, or per cent., and a very nearly equal number are cosmopolitan." the same palæontologist reminds us that by far the greater number of fossils which occur in the palæozoic strata of australia are present also in regions lying well within the limits of the north temperate zone. "in fact," he continues, "the relationship between this southern fauna and the faunas of europe and north america is so great as to practically amount to identity." but, side by side with such evidence of broad distribution, we are confronted with facts which go to show that, even at the dawn of palæozoic times, the oceanic areas at all events had their more or less distinct life-provinces. while many of the old forms were cosmopolitan, others were apparently restricted in their range. it would be strange, indeed, had it been otherwise; for, however uniform the climatic conditions may have been, still that uniformity was only comparative. an absolutely uniform world-climate is well-nigh inconceivable. all we can maintain is that the conditions during certain prolonged periods were so equable as to allow of the general diffusion of species over vastly greater areas than now; and that such conditions extended from low latitudes up to polar regions. now, among the chief factors which in our day determine the limitation of faunas and floras, we must reckon latitude and the geographical position of land and water. what, then, it may be asked, were the causes which allowed of the much broader distribution of species in former ages? it is obvious that before a completely satisfactory answer to that question can be given, our knowledge of past geographical conditions must be considerably increased. if we could prepare approximately correct maps and charts to indicate the position of land and sea during the formation of the several fossiliferous systems, we should be able to reason with some confidence on the subject of climate. but, unfortunately, the preparation of such correct maps and charts is impossible. the data for compilations of the kind required are still inadequate, and it may well be doubted whether, in the case of the older systems, we shall ever be able to arrive at any detailed knowledge of their geographical conditions. nevertheless, the geological structure of the earth's crust has been so far unravelled as to allow us to form certain general conceptions of the conditions that must have attended the evolution of our continents. and it is with such general conceptions only that i have at present to deal. i said a little ago that the question of geological climates must now be considered from the point of view of the permanency of the great dominant features of the earth's crust. i need not recapitulate the evidence upon which dana and his followers have based this doctrine of the primeval antiquity of our continental and oceanic areas. it is enough if i remind you that by continental areas we simply mean certain extensive regions in which elevation has, upon the whole, been in excess of depression; by oceanic area, on the other hand, is meant that vast region throughout which depression has exceeded elevation. thus, while the area of permanent or preponderating depression has, from earliest geological times, been occupied by the ocean, the continental areas have been again and again invaded by the sea--and even now extensive portions are under water. it is not only the continental dry land, therefore, but all the bordering belt of sea-floor which does not exceed fathoms or so in depth, that must be included in the region of dominant elevation. were the whole of this region to be raised above the level of the sea, the present continents would become connected so as to form one vast land-mass, or continental plateau. (d, plate iv.) all the sedimentary strata with which we are acquainted have been accumulated over the surface of that great plateau, and consequently are of comparatively shallow-water origin. they show us, in fact, that at no time in geological history has that plateau ever been drowned in depths at all comparable to those of the deeper portions of our oceanic troughs. the stratified rocks teach us, moreover, that the present land-areas have been gradually evolved, and that, notwithstanding many oscillations of level, these areas have continued to increase in extent--so that there is probably more land-surface now than at any previous era in the history of our globe. to give even a meagre outline of the evidence bearing upon this interesting subject is here impossible. all that i can do is to indicate very briefly some of the general results to which that evidence seems to lead. the oldest rocks with which we are acquainted are the so-called archæan schists[dj] but these have hitherto yielded no unequivocal traces of organic life, and as their origin is still doubtful, it would obviously be futile to speculate upon the geographical conditions of the earth's surface at the time of their formation. reliable geological history only begins with the fossiliferous strata of the palæozoic era. from these we learn that in the european area the archæan rocks of britain, scandinavia, and finland formed, at that time, the most extensive tract of dry land in our part of the world. how far beyond the present limits of europe that ancient northern land extended we cannot tell; but it probably occupied considerable regions which are now submerged in the waters of the arctic ocean. further south, the continental plateau appears to have been, for the most part, overflowed by a shallow sea, the surface of which was dotted by a few islands of archæan rocks, occupying the sites of what are now some of the hills of middle germany and the archæan districts of france and the iberian peninsula. archæan rocks occur likewise in corsica and sardinia, and again in turkey: they also form the nuclei of most of the great european mountain-chains, as the pyrenees, the alps, the carpathians, and the urals. these areas of crystalline schists may not, it is true, have existed as islands at the beginning of palæozoic times, for they were doubtless ridged up by successive elevations at later dates; but their very presence as mountain-nuclei is sufficient to show that at a very early geological period, the continental plateau could not have been covered by any great depth of sea. we can go further than this--for all the evidence points to the conclusion that, even so far back as cambrian times, the dominant features of the present european continent had been, as it were, sketched out. looked at broadly, that part of the great continental plateau upon which our european lands have been gradually built up may be said to be traversed from west to east by two wide depressions, separated by an intervening elevated tract. the former of these depressions corresponds to the great central plain which passes through the south of england, north-east of france, and the low countries, whence it sweeps through germany, to expand into the extensive low-grounds of central and northern russia. the southern depression embraces the maritime tracts of the mediterranean, and the regions which that sea covers. to these dominant features all the others are of subordinate importance. the two great troughs are belts of depression in the continental plateau itself. the northern one is of extreme antiquity--it is older, at all events, than the cambro-silurian period. even at that distant date its southern limits were marked out by ridges of archæan rock, which, as i have said, seem to have formed islands in what is now central europe. it was probably always the shallower depression of the two, for we have evidence to show that again and again, in mesozoic and later times, the sea that overflowed what are now the central lowlands of europe was of less considerable depth than that which occupied the mediterranean trough. [dj] i need hardly remind geologists that some of the so-called "archæan schists" may really be the highly altered accumulations of later geological periods. if we turn to north america, we find similar reason to conclude, with professor dana, that the general topography of that region had likewise been foreshadowed as far back as the beginning of the palæozoic era. dana tells us that even then the formation of its chief mountain-chains had been commenced, and its great intermediate basins were already defined. the oldest lands of north america were built up, as in europe, of azoic rocks, and were grouped chiefly in the north. archæan masses extend over an enormous region, from the shores of the arctic ocean down to the great lake country, and they are seen likewise in greenland and many of the arctic islands. they appear also in the long mountain-chains that run parallel with the coast-lines of the continent. in a word, the present distribution of the archæan rocks, and their relation to overlying strata, lead to the belief that in north america, just as in europe, they form the foundation-stones of that continent, and stretch continuously throughout its whole extent. we know comparatively little of the geology of the other great land-masses of the globe, but from such evidence as we have there is reason to believe that these in their general structure have much the same story to tell as europe and north america. in south america, archæan rocks extend over vast areas in the east and north-east, and reappear in the lofty mountain-chains of the pacific border. they have been recognised also in various parts of africa, alike in the north and east, in the interior, and in the west and south. in asia, again, they occupy wide areas in the indian peninsula; they are well developed in the himalaya, while in china and the mountains and plateaux of central asia, azoic rocks, which are probably of archæan age, are well developed. the crystalline schists, which cover extensive tracts in australia and in the northern island of new zealand, have also been referred to the same age. thus, all the world over, archæan rocks seem to form the surface of the ancient continental plateau upon which all other sedimentary strata have been accumulated. and in every region where palæozoic rocks occur, we have evidence to prove that at the time these last were formed vast areas of the old continental plateau were under water. the geological structure of the palæozoic tracts of europe and america has shown us that, during the protracted period of their accumulation, and notwithstanding many oscillations of level, the land-surface continued to increase. the same growth of dry land characterised mesozoic and cainozoic times--the primeval depressions that traverse the continental plateau became more and more silted up, and the sea eventually disappeared from extensive regions which it had overflowed in palæozoic ages. this land-growth, of course, was not everywhere continuous. again and again, throughout wide tracts, depression was in excess of sedimentation and elevation. even at the present time, broad tracts of what was once dry land are submerged. but the simple fact that the younger fossiliferous strata do not extend over such wide areas as the older systems, is sufficient proof that our land-masses have all along tended to grow, and to become more and more consolidated. reference has already been made to the remarkable fact that no abysmal accumulations have yet been detected amongst the stratified rocks of the earth's crust. ordinary clastic rocks, such as shale, sandstone, and conglomerate--altered or unaltered, as the case may be--form by far the largest proportion of our aqueous strata, and speak to us only of shallow waters. it is true that some of our limestones must have accumulated in moderately deep clear seas, yet none of these limestones is of abysmal origin. they prove that portions of the continental plateau have now and again been submerged for several thousand feet, but afford no evidence of depths comparable to those of the present oceanic basins. the enormous thickness obtained by the sedimentary strata can only be explained on the supposition that deposition took place over a gradually sinking area. and thus it can be shown that, within the continental plateau, movements of depression have been carried on more or less continuously during vast periods of time--and yet so gradually, that sedimentation was able to keep pace with them. take, for example, the cambrian strata of wales and shropshire--all, apparently, shallow-water deposits--which attain a thickness of , feet, or thereabout; or the silurian strata of the same regions, which are not much less than , feet thick; and similar great depths of sedimentary rocks might be cited from north america. passing on to later periods, we find like evidence of long-continued depression in the thick sediments of the younger palæozoic systems. it is noteworthy, however, that when we come down to still later ages, the movements of depression, as measured by the depths of the strata, appear to have become less and less extensive and profound. each such movement of depression was eventually brought to a close by one or more movements of upheaval--slowly or more rapidly effected, as the case may have been. here, then, we are confronted with the striking fact that the continental plateau has, from time to time, sunk down over wide areas to depths exceeding those of existing oceans, and yet at so slow a rate, that sedimentation prevented the depressed regions from becoming abysmal. it is obvious, then, that such areas are now dry land simply because, in the long-run, sedimentation and upheaval have been in excess of depression. and yet, notwithstanding the numerous upheavals which have taken place over the continental plateau, these have succeeded in doing little more than drain away the sea more or less completely from the great primeval depressions by which that plateau is traversed. if it be true, therefore, that the continental plateau owes its existence to the sinking down of the earth's crust within the oceanic basins--if the continents have been squeezed up by the tangential thrusts exerted by the sinking areas that surround them--then it follows that while lands have been gradually extending over the continental plateau, the bed of the ocean has been sinking to greater and greater depths. if this general conclusion holds good, it is obvious that the oceanic troughs of early geological times could not have been so deep as they are now. during the palæozoic period, the most continuous areas of dry land, as we have seen, were distributed over the northern parts of our hemisphere, while, further south, groups of islands indicated the continuation of the continental plateau. doubtless south america, africa, asia, and australia were, at that distant date, represented by similar detached areas of dry land. in a word, the primeval continental plateau was still largely under water. judging from the character and broad distribution of the palæozoic marine faunas the temperature of the sea was wonderfully uniform. there is certainly nothing to indicate the existence of such climatic zones as those of the present. we know very little of the terrestrial life of early palæozoic times--the cambro-silurian strata are essentially marine. land-plants, however, become more numerous in the old red sandstone, and, as every one knows, they abound in the succeeding carboniferous and permian systems. and the testimony of these floras points to the same conclusion as that furnished by the marine faunas. the carboniferous floras of the arctic regions, and of temperate europe and america, not only have the same _facies_, but a considerable number of the species is common to both areas; while many european species occur in the carboniferous strata of australia and other distant lands. this common _facies_, and the presence of numerous cosmopolitan forms, surely indicate the former prevalence of remarkably uniform climatic conditions. the conditions, of course, need not--indeed, could not--have been absolutely uniform. at present the various climates which our globe experiences depend upon the amount of heat received directly and indirectly from the sun--oceanic and aërial currents everywhere modifying the results that are due to latitude. it cannot have been otherwise in former times. in all ages the tropics must have received more direct sun-heat than temperate and polar regions; and however much the climatic conditions of the palæozoic era may have differed from the present--however uniformly temperature may have been distributed--still, as i have said, absolute uniformity was impossible. it was doubtless owing to the fact that the dry lands of palæozoic times were not only much less extensive than now, but more interrupted, straggling, and insular, that the climate of the globe was so equable. under such geographical conditions, great oceanic currents would have a much freer course than is now possible, and warm water would find its way readily across wide regions of the submerged continental plateau into the highest latitudes. the winds blowing athwart the land would everywhere be moist and warm, and no such marked differences of temperature, such as now obtain, would distinguish the arctic seas from those of much lower latitudes. at the same time, the comparatively shallow water overlying the submerged areas of the continental plateau would favour the distribution of species, and thus bring about that wide distribution of cosmopolitan forms and general similarity of _facies_, which are such marked features of the palæozoic faunas. it is even quite possible that migration may have taken place here and there across the great oceanic depression itself; for it may well be doubted whether, at so early a period, the depression had sunk down to its present depth below the level of the continental plateau. yet, notwithstanding such facilities for migration, and the consequent similarity of _facies_ i have referred to, the palæozoic faunas of different regions have usually certain distinctive characters. even at the very dawn of the era the marine faunas were already grouped into provinces, sometimes widely separated from one another, at other times closely adjacent, so that it is evident that barriers to migration here and there existed. it could hardly have been otherwise; for local and more widely-spread movements of elevation and depression took place again and again during palæozoic times. while the younger palæozoic systems were being accumulated, excess of upheaval over depression resulted in the gradual increase of the land.[dk] the continental plateau came more and more to the surface, in spite of many oscillations of level. it is quite possible, nay, even probable that this persistent growth of land, and consequent modification of oceanic currents may have rendered the climatic conditions of later palæozoic times less uniform: but, if so, such diminished uniformity has left no recognisable impress on either faunas or floras; for fossils characteristic of the devonian and carboniferous strata of temperate latitudes occur far within the arctic circle. [dk] see footnote p. . descending to the mesozoic era, we find that the character and distribution of marine faunas are still indicative of uniformity. there could have been little difference of temperature at that time between arctic seas and those of our own latitude. cosmopolitan species abounded in the jurassic waters, but were relatively less numerous in those of the cretaceous period. professor neumayr maintains that already, in the jurassic period, the climate had become differentiated into zones. this, he thinks, is indicated by the fact that coral reefs abound in the jurassic strata of central europe, while they are wanting in the contemporaneous deposits of boreal regions. dr. heilprin, on the other hand, is of opinion that this and certain other distinctive features of separate jurassic life-provinces may not have been due to differences of temperature, but rather to varying physical conditions, such as character of the sea-bottom, depth of water, and so forth. perhaps the safest conclusion we can come to, in the present state of the evidence, is that the climatic conditions of the mesozoic era were, upon the whole, less obviously uniform than those of earlier ages, but that marked zones of climate like the present had not as yet been evolved. at the same time, when we consider how many great geographical revolutions took place during the period in question, we must be prepared to admit that these could hardly fail to influence the climate, and thus to have induced modifications in the distribution of faunas and floras. and probably evidence of such modifications will yet be recognised, if indeed the phenomena referred to by neumayr be not a case in point. it may be noted, further, that while, according to many botanists, the plants of the palæozoic periods bespeak not only uniform climatic conditions but the absence of marked seasonal changes, those of late mesozoic times are indicative of less uniformity. the cretaceous conifers, for example, show regular rings of growth, and betoken the existence of seasons, which were less marked, however, than is now the case. the geographical changes of mesozoic times were notable in many respects. the dominant features of europe, already foreshadowed in early palæozoic times, had become more clearly outlined before the close of the cretaceous period. notwithstanding many movements of depression, the chief land-areas continued to show themselves in the north and north-west. the highest grounds were the urals, and the uplands of scandinavia and britain. in middle europe the pyrenees and the alps were as yet inconsiderable heights, the loftiest lands in that region being those of the harz, the riesen gebirge, and other tracts of archæan and palæozoic rocks. the lower parts of england and the great lowland plains of central europe were sometimes submerged in the waters of a wide, shallow sea, but ever and anon elevation ensued, new lands appeared, and these waters became divided into a series of large inland seas and lakes. in the south, a deep mediterranean sea would appear to have persisted all through the mesozoic era--a sea of considerably greater extent, however, than the present. while in europe the dominant features of the continental plateau run approximately east and west, in north america they follow nearly the opposite direction. in early mesozoic times, vast tracts of dry land extended across the northern and eastern sections of the latter area. over the rocky mountain region, low lands and saline lakes appear to have stretched, while further west the area of the great plateau and the pacific slope were covered by the sea. towards the end of the mesozoic era, the land in the far west became more continuous--a broad belt extending in the direction of the pacific coast-line from mexico up to high northern latitudes. in short, before the cretaceous period closed, the major portion of north america had been evolved. a considerable tract of what is now the western margin of the continent, however, was still under water, while from the gulf of mexico (then much wider than now) a broad mediterranean sea swept north and north-west through texas and the rocky mountain region to communicate with the arctic ocean. all to the east of this inland sea was then, as it is now, dry land. thus, up to the close of the cretaceous period, in america and europe alike, oceanic currents coming from the south had ready access across the primeval continental plateau to the higher latitudes. southern europe indeed, during mesozoic times, was simply a great archipelago, having free communication on the one hand across the low-grounds of central and northern russia with the arctic seas, and, on the other, across vast regions in asia with the indian ocean. of the other great land-masses of the globe our knowledge is too limited to allow us to trace their geographical evolution with any confidence. but from the very wide distribution of mesozoic strata in south america, africa, asia, and australia, there can be no doubt that, at the time of their accumulation, enormous tracts in those regions were then under water. the land-masses, in short, were not so continuous and compact as they are at present. and although we must infer that considerable areas of mesozoic land are now submerged, yet these cannot but bear a very small proportion to the wide regions which have been raised above the sea-level since mesozoic times. in short, from what we do know of the geological structure of the continents in question, we can hardly doubt that they have passed through geographical revolutions of a like kind with those of europe and north america. everywhere over the great continental plateau elevation appears, in the long-run, to have been in excess of depression, so that, in spite of many subsidences, the tendency of the land throughout the world has been to extend its margins, and to become more and more consolidated. the mesozoic lands were larger than those of the preceding palæozoic era, but they were still penetrated in many places by the sea, and warm currents could make their way over wide tracts that are now raised above the sea-level. under such circumstances approximately uniform conditions of climate could not but obtain. great geographical changes supervened upon the close of the cretaceous period. north america then acquired nearly its present outline. its mediterranean sea had vanished, but the gulf of mexico still overflowed a considerably wider region than now, while a narrow margin of the pacific border of the continent continued submerged. in europe elevation ensued, and the sea which had overspread so much of the central and eastern portions of our continent disappeared. southern europe, however, was still largely under water, while bays and inlets extended northwards into what are now the central regions of the continent. on to the close of the miocene period, indeed, the southern and south-eastern tracts of europe were represented by straggling islands. in middle cainozoic times the alps, which had hitherto been of small importance, were considerably upheaved, as were also the pyrenees and the carpathians; and a subsequent great elevation of the alpine area was effected after the miocene period. notwithstanding these gigantic movements, the low-lying tracts of what is now southern europe continued to be largely submerged, and even the central regions of the continent were now and again occupied by broad lakes, which sometimes communicated with the sea. after the elevation of the miocene strata, these inland seas disappeared, but the mediterranean still overflowed wider areas than it does to-day. eventually, however, in late pliocene times, the bed of that sea experienced considerable elevation; and it was probably at or about this stage that the black sea and the sea of asov retreated from the broad low-grounds of southern russia, and that the inland seas and lakes of austria-hungary finally vanished. the movements of upheaval, which caused the cretaceous seas to disappear from such broad areas of the continental plateau, induced many changes in the floras and faunas of the globe. a notable break in the succession occurs between the cretaceous and the eocene, hardly one species of higher grade than the protozoa passing from one system to the other. in the cainozoic deposits we are no longer confronted with numerous cosmopolitan species--the range of marine forms has become much more restricted. nevertheless, the faunas and floras continue to be indicative of much warmer climates for arctic and temperate latitudes than now obtain. but, at the same time, differentiation of climate into zones is distinctly marked. in the early cainozoic period, our present temperate latitudes supported a flora of decidedly tropical affinities, while the fauna of the adjacent seas had a similar character. later on the climate of the same latitudes appears to have passed successively through sub-tropical and temperate stages. in short, a gradual lowering of the temperature is evinced by the character and distribution both of floras and faunas. the differentiation of the climate during one stage of the cainozoic era is well illustrated by the miocene flora. thus, at a time when italy was clothed with a tropical vegetation, in which palm-trees predominated, middle europe had its extensive forests of evergreens and conifers, while in the region of the baltic conifers and deciduous trees were the prevalent forms. when one takes into consideration the fact that, notwithstanding many oscillations of level, the land during cainozoic times was gradually extending, and the sea disappearing from wide regions which it had formerly covered, one can hardly doubt that the seemingly gradual change from tropical to temperate conditions was due, in large measure, to that persistent continental growth. i confess, however, that it is difficult to account for the very genial climate which continued to prevail over the arctic regions. so far as one can gather from the evidence at present available, some of the marine approaches to those latitudes had been cut off by the movements of elevation which brought the cainozoic era to a close, while the arctic lands were perhaps more extensive than they are now. the cretaceous mediterranean sea of north america had vanished, and we cannot prove that the tertiary sea of southern europe communicated across the low-grounds of russia with the arctic ocean. we know, however, that the archipelago of southern europe was in direct connection with the indian ocean, and it is most probable that a wide arm of the same sea stretched north from the aralo-caspain area through siberia. indeed, much of what are now the lowlands of western and northern asia was probably sea in tertiary times. it seems likely, therefore, that, even at this late period, marine currents continued to reach the arctic zone across the continental plateau. when the warm waters of the indian ocean eventually ceased to invade europe, and the mediterranean became much restricted in area, the climate of the whole continent could not fail to be profoundly affected. there is yet another line of evidence to which brief reference may be made. i have spoken of the remarkable uniformity of climatic conditions which obtained in palæozoic times, and of the gradual modification of these conditions which subsequently supervened. now, it is worthy of note that in their lithological characters the oldest sedimentary strata themselves likewise exhibit a prevalent uniformity which in later systems becomes less and less conspicuous. the cambro-silurian mechanical sediments, for example, maintain much the same character all the world over; and the like is true, although in a less degree, of the marine accumulations of the devonian period. the corresponding mechanical deposits of later palæozoic ages continue to show more and more diversity, but at the same time they preserve a similarity of character over much more extensive areas than is found to be the case with the analogous sediments of the mesozoic era. finally, these last are more or less strongly contrasted with the marine mechanical accumulations of cainozoic times, which are altogether more local in character. this increasing differentiation is quite in keeping with what we know of the evolution of our land-areas. in early palæozoic ages, when insular conditions prevailed and the major portion of the primeval continental plateau was covered by shallow seas, it is obvious that mechanical sediments would be swept by tidal and other currents over enormous areas, and that these sediments would necessarily assume a more or less uniform character. indeed, i suspect that much of the sediment of those early seas may have been the result of tidal scour, and that marine erosion was more generally effective then than it is now. with the gradual growth of the land and the consequent deflection and limitation of currents, marine mechanical sediments would tend to become more and more local in character. thus the increasing differentiation which we observe in passing from the earlier to the later geological systems is just what might have been expected. summing up, now, the results of this rapid review of the evidence, we seem justified in coming to the following conclusions:-- ( .) in palæozoic times, europe and north america were represented by considerable areas of dry land, massed chiefly in the higher latitudes, while further south groups of smaller islands were scattered over the submerged surface of the primeval continental plateau. the other continents appear, in like manner, to have been represented by islands--some of which may have reached continental dimensions. a very remarkable uniformity of climate accompanied these peculiar geographical conditions. ( .) in mesozoic times, the primeval continental plateau came more and more to the surface, but the land-areas were still much interrupted, so that currents from tropical regions continued to have ready access to high latitudes. the climate of the whole globe, therefore, was still uniform, but apparently not so markedly as in the preceding era. ( .) in cainozoic times, the land-masses continued to extend, and the sea to retreat from hitherto submerged areas of the continental plateau; and this persistent land-growth was accompanied by a gradual lowering of the temperature of northern and temperate latitudes, and a more and more marked differentiation of climate into zones. having thus very briefly sketched the geographical evolution of the land during palæozoic, mesozoic, and tertiary times, and come to the general conclusion that climate has varied according to the relative position of land and sea, i have next to consider the geographical and climatic conditions of the quaternary period. these, however, are now so well known, that i need to no more than remind you that, so far as the chief features of our lands are considered, all these had come into existence before the dawn of the ice age. the greater contours of the surface, which were foreshadowed in palæozoic times, and which in mesozoic times were more clearly indicated, had been fully evolved by the close of the pliocene period. the connection between the mediterranean and the indian ocean probably ceased in late pliocene times. the most remarkable geographical changes which have taken place since then within european regions have been successive elevations and depressions, in consequence of which the area of our continent has been alternately increased and diminished. at a time well within the human period, our own islands have been united to themselves and the continent, and the dry land has extended north-west and north, so as to include spitzbergen, the faröe islands, and perhaps iceland. on the other hand, our islands have been within a recent period largely submerged. similarly, in north america, we are furnished with many proofs of like oscillations of level having taken place in quaternary times. is it possible, then, to explain the climatic vicissitudes of the pleistocene period by means of such oscillations? many geologists have tried to do so, but all these attempts have failed. it is quite true that a general elevation of the land in high latitudes would greatly increase the ice-fields of arctic regions, and might even give rise to perennial snow and glaciers in the mountain-districts of our islands. but it is inconceivable that any such geographical change could have brought about that general lowering of temperature over the whole northern hemisphere which took place in pleistocene times. for we have to account not only for the excessive glaciation of northern and north-western europe, and of the northern parts of north america, but for the appearance of snow-fields and glaciers in much more southern latitudes, and in many parts of asia where no perennial snow now exists. moreover, we have to remember that arctic conditions of climate obtained in north-western europe even when the land was relatively much lower than it is at present. the arctic shell-beds of our own and other temperate regions sufficiently prove that geographical conditions were not the only factor concerned in bringing about the peculiar climate of the pleistocene period. then, again, we must not forget that at certain stages of the same period genial conditions of climate were coincident with a much wider land-surface in north-western europe than now exists. the very fact that interglacial deposits occur in every glaciated region is enough of itself to show that the arctic conditions of the pleistocene could not have resulted entirely from a mere elevation of land in the northern parts of our hemisphere. the only explanation of the peculiar climatic vicissitudes in question which seems to meet the facts, so far as these have been ascertained, is the well-known theory advanced by dr. croll. after carefully considering all the objections which have been urged against that theory, there is only one, as it seems to me, that is deserving of serious attention. this objection is not based on any facts connected with the pleistocene deposits themselves, but on evidence of quite another kind. it is admitted that were the pleistocene deposits alone considered, croll's theory would fully account for the phenomena. but, it is argued, we cannot take the pleistocene by itself, for if that theory be true, then climatic conditions similar to those of the pleistocene must have supervened again and again during the past. where, then, we are asked, is there any evidence in palæozoic, mesozoic, or cainozoic strata of former widespread glacial conditions? if continental ice-sheets, comparable to those of the pleistocene, ever existed in the earlier ages, surely we ought to find more or less unmistakable traces of them. now, at first sight, this looks a very plausible objection, but it has always seemed to me to be based upon an assumption that is not warranted by our knowledge of geographical evolution. dr. croll always admitted implicitly that high eccentricity of the earth's orbit might have happened again and again without inducing glacial conditions like those of the pleistocene. the objection takes no account of the fact that the excessive climate of the glacial period was only possible because of special geographical conditions--conditions that do not appear to have been fully evolved before pliocene times. no one has seen this more clearly than mr. wallace,[dl] with the general drift of whose argument i am quite at one. in earlier ages, the warm water of the tropics overflowed wide areas of our present continents--most of the dry land was more or less insular, and the seas within the arctic circle were certainly not cold as at present, but temperate and even genial. if we go back to cambro-silurian times, we find only the nuclei, as it were, of our existing continents appearing above the surface of widespread shallow seas. it is quite impossible, therefore, that under such geographical conditions, great continuous ice-sheets, like those of the pleistocene, could have existed--no matter how high the eccentricity of the earth's orbit may have been. the most that could have happened during such a period of eccentricity would be the accumulation of snow-fields on mountains and plateaux of sufficient height, the formation here and there of local glaciers, and the descent of these in some places to the sea. and what evidence of such local glaciation might we now expect to find? no old land-surface of that far-distant period has come down to us: we look in vain for cambro-silurian _roches moutonnées_ and boulder-clay or moraines. the only evidence we could expect is just that which actually occurs, namely, erratics (some of them measuring five feet and more in diameter) embedded in marine deposits. it may be said that a few erratics are hardly sufficient to prove that a true glacial period supervened in cambro-silurian times, and i do not insist that they are. but i certainly maintain that if any lowering of the temperature were induced by high eccentricity of the earth's orbit during cambro-silurian times, then ice-floated erratics are the only evidence of refrigeration that we need ever hope to find. the geographical conditions of early palæozoic times forbade the formation of enormous ice-sheets like those of the pleistocene period. extreme climatic changes were then impossible, and periods of high eccentricity might have come and gone without inducing any modifications of flora and fauna which we could now recognise. we are ignorant of the terrestrial life of the globe at that distant period, and our knowledge of the marine fauna is not sufficient to enable us to deny the possibility of moderate fluctuations in the temperature of the seas of early palæozoic times. moreover, we must not forget there were then no such barriers to migration as now exist. if the conditions became temporarily unsuitable, marine organisms were free to migrate into more genial waters, and to return to their former habitats when the unfavourable conditions had passed away. [dl] see _island life_. the uniform climate so characteristic of the cambro-silurian period appears to have prevailed likewise during the later stages of the palæozoic era. this we gather from a general consideration of the floras and faunas, and their geographical distribution. the dry land, as we have seen, continued to increase in extent; but vast areas of the primeval continental plateau of the globe still continued under water, and currents from southern latitudes flowed unrestricted into polar regions. during the protracted lapse of time required for the formation of the later palæozoic systems several periods of high eccentricity must have occurred. but, so far as one can judge, the disposition of the larger land-areas was never such as to induce a true ice age. nevertheless we are not without evidence of ice-action in old red sandstone, carboniferous, and permian strata. and it seems to me probable that the erratic accumulations referred to may really indicate local action, of more or less intensity, brought about by such lowering of the temperature as would supervene during a period of high eccentricity. it is true we may explain the phenomena by inferring the existence of mountains of sufficient elevation--and this, indeed, is the usual explanation. but it is doubtful whether those who adopt that view have fully considered what it involves. take, for example, the case of the breccias and conglomerates of the lammermuir hills, which have all the appearance of being glacial and fluvio-glacial detritus. these deposits overlie the highly-denuded silurian greywackés of haddingtonshire in the north and of berwickshire in the south, and have evidently been derived from the intervening high-grounds--the width of which between the old red sandstone accumulations in question does not exceed eight or nine miles. the breccias reach a height of feet, while the dominating point of the intervening uplands is feet. under present geographical conditions it is doubtful whether perennial snow and glaciers of any size at all could exist in the region of the lammermuirs at a less altitude than feet or more. but between the breccias of haddingtonshire and the equivalent deposits in berwickshire there is no space for any intermediate range of mountains of circumdenudation of such a height. moreover, we must remember that under the extremely uniform conditions which obtained in palæozoic times the snow-line could not possibly have been attained even at that elevation. when the devonian coral-reefs described by dupont were growing in the sea that overflowed western europe, to what height must the southern uplands of scotland have been elevated in order to reach the snow-line! we may make what allowance we choose for the denudation which the silurian rocks of the lammermuirs must have experienced since the deposition of the old red sandstone, but it is simply a physical impossibility that mountains of circumdenudation of the desiderated height could ever have existed in the lammermuir region at the time the coarse breccias were being accumulated.[dm] it seems to me, then, that these breccias are in every way better accounted for by a lowering of temperature due to increased eccentricity of the orbit. this view frees us from the necessity of postulating excessive upheavals over very restricted areas, and of creating alps where no alps could have existed. [dm] it may be objected that the conglomerates were probably not marine, but deposited in lakes, the beds of which may have been much above sea-level. but from all that we know of the old red sandstone of scotland it would appear that the lakes of the period now and again communicated with the sea, and were probably never much above its level. when we consider the enormous thickness of the strata that constitute any of our larger coal-fields, we can hardly doubt that one or more periods of high eccentricity must have occurred during their accumulation. it does not follow, however, that we should be able to detect in these strata any evidence of alternating cold and warm epochs. so long as ocean-currents from the tropics found ready entrance to polar regions across vast tracts of what is now dry land, extreme and widespread glacial conditions were impossible. any lowering of temperature due to cosmical causes might indeed induce new snow-fields and glaciers to appear, or existing ones to extend themselves in northern regions and the most elevated lands of lower latitudes; but such local glaciation need not have seriously affected any of the areas in which coal-seams were being formed. for nothing appears more certain than this--that our coal-seams as a rule were formed over broad, low-lying alluvial lands, and in swamps and marshes, along the margins of estuaries or shallow bays of the sea. some seams, it is true, are evidently formed of drifted vegetable débris, but the majority point to growth _in situ_. the strata with which they are associated are shallow-water sediments which could only have been deposited at some considerable distance from any mountain-regions in which glaciers were likely to exist. it is idle, therefore, to ask for evidence of glacial action amongst strata formed under such conditions. the only evidence of ice-work we are likely to get is that of erratics. and these are not wanting, although it is probable that most of those which are found embedded in coals have been transported by rafts of vegetable matter or in the roots of trees. the same explanation, however, will not account for the boulders which sir william dawson has recorded from the coal-fields of nova scotia. he describes them as occurring on the outside of a gigantic esker of carboniferous age, and thinks they were probably dropped there by floating-ice at a time when coal-plants were flourishing in the swamps on the other side of the gravel embankment. if the disposition of the land-areas in carboniferous times rendered such an ice-age as that of the pleistocene impossible--in other words, if the effects flowing from high eccentricity of the orbit must to a large extent have been neutralised--the flora and fauna of the period can hardly be expected to yield any recognisable evidence of fluctuating climatic conditions. when our winter happened in aphelion new snow-fields might have appeared, or already existing glaciers might have increased in size; while, with the winter in perihelion, the temperature in northern latitudes would doubtless be raised. but the general result would simply be an alternation of warm and somewhat cooler conditions. and such fluctuations of climate might readily have taken place without materially modifying; the life of the period. the breccias of the permian system have been described by ramsay as of glacial origin. some geologists agree with him, while others do not--and many have been the ingenious suggestions which these last have advanced in explanation of the phenomena. some have tried to show how the stones and blocks in the breccias may have been striated without having recourse to the agency of glacier-ice, but they cannot explain away the fact that many of the stones (which vary in size from a few inches to three or four feet in diameter) have travelled distances of thirty or forty miles from the parent rocks. similar erratic accumulations, which may belong to the same system or to the carboniferous, occur in india and australia. according to dr. blanford, the indian boulder-beds are clearly indicative of ice-action, and he does not think that they can be explained by an assumed former elevation of the himalaya. on the contrary, he is of opinion that the facts are best accounted for by a general lowering of the temperature, due probably to the action of cosmical causes. daintree, wilkinson, r. oldham, and others who have studied the australian erratic beds have likewise stated their belief that these are of true glacial origin. i may pass rapidly over the mesozoic systems, taking note, however, of the fact that in them we encounter evidence of ice-action of much the same kind as that met with in palæozoic strata. while, on the one hand, the mesozoic floras and faunas bespeak climatic conditions similar to those of earlier ages, but probably not quite so uniform; on the other, the occurrence of erratics in various marine accumulations is sufficient to show that now and again ice floated across seas, the floors of which were tenanted by reef-building corals. the geographical conditions continued unfavourable to the formation of extensive ice-sheets in temperate latitudes, no matter how high the eccentricity of the orbit might have been. the erratics which occur in certain jurassic and cretaceous deposits are admitted by most geologists to have been ice-borne. now, it is highly improbable that the transporting agent could have been coast-ice, for it is hardly possible to conceive of ice forming on the surface of a sea in which flourished an abundant mesozoic fauna. the erratics, therefore, seem to imply the existence in mesozoic times of local glaciers, which here and there descended to the sea, as in the north-east of scotland. the erratics in the scottish jurassic are evidently of native origin, and it is most improbable that those which have been met with in the chalk of england and france could have floated from any very great distance. how, then, can we explain the appearance of local glaciers in these latitudes during mesozoic times? the geographical conditions of the period could not have favoured the formation of perennial snow and ice in our area, unless our lands were at that time much more elevated than now. and this is the usual explanation. it is supposed that mountains much higher than any we now possess probably existed in such regions as the scottish highlands. it is easy to imagine the former existence of such mountains. so long a time has elapsed since the jurassic period, that the archæan and palæozoic areas cannot but have suffered prodigious denudation in the interval. but, when one considers how very lofty, indeed, those mountains must have been, in order to reach the snow-line of jurassic times, one may be excused for expressing a doubt as to whether the suggested explanation is reasonable. at all events, the phenomena are, to say the least, as readily explicable on the supposition that the snow-line was temporarily lowered by cosmical causes. even with eccentricity at a high value, no great ice-sheets, indeed, could have existed, but local snow-fields and glaciers might have appeared in such mountain-regions as were of sufficient height. and this might have happened without producing any great difference in the temperature of the sea, or any marked modification in the distribution of life. in short, we should simply have, as before, an alternation of warm and somewhat cooler climates, but nothing approaching to the glacial and interglacial epochs of the pleistocene. these conclusions seem to me to be strongly supported by the evidence of ice-action during tertiary times. the gigantic erratics of the alpine eocene do not appear to have been derived from the alps, but rather from the archæan area of southern bohemia. the strata in which they occur are, for the most part, unfossiliferous; they contain only fucoidal remains, and are presumably marine. how is it possible to account for the appearance of these erratics in marine deposits in central europe at a time when, as evidenced by the eocene flora and fauna the climate was warm? are we to infer the former existence of an extremely lofty range of bohemian alps which has since vanished? is it not more probable that here, too, we have evidence of a lowering of the snow-line, induced by cosmical causes, which brought about the appearance of snow-fields and glaciers in a mountain-tract of much less elevation than would have been required in the absence of high eccentricity of the orbit? if it be objected that such cosmical causes must have had some effect upon the distribution of life, i reply that very probably they had, although not to any extreme extent. the researches of mr. starkie gardner have shown that the flora of the english eocene affords distinct evidence of climatic changes. but as the geographical conditions of that period precluded the possibility of extensive glaciation, and could only, at the most, have induced local glaciers to appear in elevated mountain-regions, it seems idle to cite the non-occurrence of erratics and morainic accumulations in the eocene of england and france as an argument against the application of croll's theory to the case of the erratics of the flysch. i repeat, then, that under the geographical conditions of the eocene, all the more obvious effects likely to have resulted from the passage of a period of high eccentricity would be the appearance of a few local glaciers, the existence of which could have had no more influence on the climate of adjacent lowlands than is notable in similar circumstances in our own day. it is absurd, therefore, to expect to find evidence in eocene strata of as strongly contrasted climates as those of the glacial and interglacial deposits of the pleistocene. there must, doubtless, have been alternations of climate in our hemisphere; but these would consist simply of passages from warm to somewhat cooler conditions--just such changes, in fact, as are suggested by the plants of the english eocene. the evidence of ice-action in the miocene strata is even more striking than that of which i have just been speaking. the often-cited case of the erratics of the superga near turin i need do little more than mention. these erratics were undoubtedly carried by icebergs, calved from alpine glaciers at a time when northern italy was largely submerged. the erratic deposits are unfossiliferous, and are underlaid and overlaid by fossiliferous strata, in none of which are any erratics to be found. what is the meaning of these intercalated glacial accumulations? can we believe it possible that the miocene glaciers were enabled to reach the sea in consequence of a sudden movement of elevation, which must have been confined to the alps themselves? then, if this be so, we must go a step further, and suppose that, after some little time, the alps were again suddenly depressed, so that the glaciers at once ceased to reach the sea-coast. for, as dr. croll has remarked, "had the lowering of the alps been effected by the slow process of denudation, it must have taken a long course of ages to have lowered them to the extent of bringing the glacial state to a close." and we should, in such a case, find a succession of beds indicating a more or less protracted continuance of glacial conditions, and not one set of erratic accumulations intercalated amongst strata, the organic remains in which are clearly suggestive of a warm climate. the occurrence of erratics in the miocene of italy is all the more interesting from the fact that in the miocene of france and spain similar evidence of ice-action is forthcoming. opponents of dr. croll's theory have made much of baron nordenskiöld's statement that he could find no trace of former glacial action in any of the fossiliferous formations within the arctic regions. he is convinced that "an examination of the geognostic condition, and an investigation of the fossil flora and fauna of the polar lands, show no signs of a glacial era having existed in those parts before the termination of the miocene period." well, as we have seen, there is no reason to believe that the geographical conditions in our hemisphere, at any time previous to the close of the pliocene period, could have induced glacial conditions comparable to those of the pleistocene ice age. the strata referred to by nordenskiöld, are, for the most part, of marine origin, and their faunas are sufficient to show us that the arctic seas were formerly temperate and genial. if any ice existed then, it could only have been in the form of glaciers on elevated lands. and it is quite possible that these, during periods of high eccentricity, may have descended to the sea and calved their icebergs; and, if so, erratics may yet be found embedded here and there in the arctic fossiliferous formations, although nordenskiöld failed to see them. one might sail all round the palæozoic coast-lines of scotland without being able to observe erratics in the strata, and yet, as we know, these have been encountered in the interior of the country. the wholesale scattering of erratics at any time previous to the pleistocene, must have been exceptional even in arctic regions, and consequently one is not surprised that they do not everywhere stare the observer in the face. the general conclusion, then, to which i think we may reasonably come, is simply this:--that geological climate has been determined chiefly by geographical conditions. so long as the lands of the globe were discontinuous and of relatively small extent, warm ocean-currents reaching polar regions produced a general uniformity of temperature--the climate of the terrestrial areas being more or less markedly insular in character. under these conditions, the sea would nowhere be frozen. but when the land-masses became more and more consolidated, when owing to the growth of the continents the warm ocean-currents found less ready access to arctic regions, then the temperature of those regions was gradually lowered, until eventually the seas became frost-bound, and the lands were covered with snow and ice. but while the chief determining cause of climate has been the relative distribution of land and water, it is impossible to doubt that during periods of high eccentricity of the orbit, the climate must have been modified to a greater or less extent. in our own day the geographical conditions are such that, were eccentricity to attain a high value, the climate of the pleistocene would be reproduced, and our hemisphere would experience a succession of alternating cold and genial epochs. but in earlier stages of the world's history, the geographical conditions were not of a kind to favour the accumulation of vast ice-fields. during a period of extreme eccentricity, there would probably be fluctuations of temperature in high latitudes; but nothing like the glacial and interglacial epochs of the pleistocene could have occurred. at most, there would be a general lowering of the temperature, sufficient to render the climate of arctic seas and lands somewhat cooler, and probably to induce the appearance in suitable places of local glaciers; and, owing to precession of the equinox, these cooler conditions would be followed by a general elevation of the temperature above the normal for the geographical conditions of the period. in palæozoic and mesozoic times, the effects of high eccentricity of the orbit appear to have been, in a great measure, neutralised by the geographical conditions, with a possible exception in the permian period. but in tertiary times, when the land-masses had become more continuous, the cosmical causes of change referred to must have had greater influence. and i cannot help agreeing with dr. croll that the warm climates of the arctic regions during that era were, to some extent, the result of high eccentricity. in concluding this discussion, i readily admit that our knowledge of geographical evolution is as yet in its infancy. we have still very much to learn, and no one will venture to dogmatise upon the subject. but i hope i have made it clear that the evidence, so far as it goes, does not justify the confident assertions of dr. croll's opponents, that his theory is contradicted by what we know of the climatic conditions of palæozoic, mesozoic, and cainozoic times. on the contrary, it seems to me to gain additional support from the very evidence to which nordenskiöld and others have appealed. note.--the accompanying sketch-maps (plate iv.) require a few words of explanation. the geology of the world is still so imperfectly known that any attempt at graphic representation of former geographical conditions cannot but be unsatisfactory. the approximate positions of the chief areas of predominant elevation and depression during stated periods of the past may have been ascertained in a general way; but when we try to indicate these upon a map, such provisional reconstructions are apt to suggest a more precise and definite knowledge than is at present attainable. for it must be confessed that there is hardly a line upon the small maps (a, b, c) which might not have been drawn differently. this, of course, is more especially true of south america, africa, asia--of large areas of which the geological structure is unknown. but although the boundaries of the land-masses shown upon the maps referred to are thus confessedly provisional, the maps nevertheless bring out the main fact of a gradual growth and consolidation of the land-areas--a passage from insular to continental conditions. i need hardly say this is no novel idea. it was clearly set forth by professor dana upwards of forty years ago (_silliman's journal_, , p. ; , pp. , ), and it received some years later further illustration from professor guyot, who insisted upon the insular character of the climate during palæozoic times (_the earth and man_, ). it must be understood that the maps (a, b, c) are not meant to exhibit the geographical conditions of the world at any one point of time. in map a, for example, the area coloured blue was not necessarily covered by sea at any particular stage in the palæozoic era. it simply represents approximately the regions tended. but, as already stated, numerous oscillations of level occurred in palæozoic times, so that many changes in the distribution of land and water must have taken place down to the close of the permian period. the land-areas shown upon the map are simply those which appear to have been more or less persistent through all the geographical changes referred to. similar remarks apply to the other maps representing the more or less persistent land-areas of mesozoic and tertiary times. thus, for example, there are reasons for believing that madagascar was joined to the mainland of africa at some stage of the mesozoic era, but was subsequently insulated before tertiary times. again, as mesozoic era a land-connection obtained between new zealand and australia. the same naturalist also points out that a chain of islands, now represented by numerous islets and shoals, served in tertiary times to link madagascar to india. map d shows the areas of predominant elevation and depression. the area coloured brown represents the great continental plateau, which extends downwards to fathoms or so below the present sea-level. the area tinted blue is the oceanic depression. from the present distribution of plants and animals, we infer that considerable tracts which are now submerged have formerly been dry land--some of these changes having taken place in very recent geological times. and the same conclusions are frequently suggested by geological evidence. there can be little doubt that europe in tertiary times extended further into the northern ocean than it does now. and it is quite possible that in the mesozoic and palæozoic eras considerable land-areas may likewise have appeared here and there in those northern regions which are at present under water. there is, indeed, hardly any portion of the continental plateau which is now submerged that may not have been land at some time or other. but after making all allowance for such possibilities, the geological evidence, as far as it goes, nevertheless leads to the conclusion that upon the whole a wider expense of primeval continental plateau has come to the surface since tertiary times than was ever exposed during any former period of the world's history. [mr. marcou states (_american geologist_, , p. ) that the idea of a gradual growth of land-areas originated with elie de beaumont, who was in the habit of showing such maps, and used them in his lectures at paris as early as . professor beudant published three of these same maps for the jurassic, cretaceous, and tertiary seas in his _cours élémentaire de géologie_ ( ); and professor carl vogt in his _lehrbuch der geologie und petrefactenkunde_ ( ), which was confessedly based on elie de beaumont's lectures during - , gives four maps of the carboniferous, jurassic, cretaceous, and tertiary seas.] xiii. the scientific results of dr. nansen's expedition.[dn] [dn] from _the scottish geographical magazine_, . in the appendix to his most interesting and instructive work, _the first crossing of greenland_, dr. nansen treats of the scientific results of his remarkable journey. the detailed enumeration of these results, he tells us, would have been out of place in a general account of his expedition, but will appear in due time elsewhere. hence he confines attention in his present work to such questions as are of most obvious interest, such as the extent, outward form, and elevation of the inland-ice of greenland. by way of introduction his readers are presented with some account of the geological history of the country, which, although it contains nothing that was not already familiar to geologists, will doubtless prove interesting to others. after indicating that greenland would appear to be composed almost exclusively of archæan schists and granitoid eruptive rocks, the author glances at the evidence which the mesozoic and cainozoic strata of the west coast have supplied as to the former prevalence of genial climatic conditions. heer is cited to show that during the formation of the cretaceous beds the mean temperature of north greenland was probably between ° and ° f., while in later cainozoic times it could not have been less than ° f., in ° n.l. these conclusions are based on the character of the fossil floras. now the mean annual temperature on the west coast of greenland, where the relics of these old floras occur, is about ° f., from which it is inferred that there has been a decrease of ° since cainozoic times. in those times, says dr. nansen, "the country must have rejoiced in a climate similar to that of naples, while in the earlier cretaceous period it must have resembled that of egypt." he then refers to the well-known fact that, long after the deposition of the cainozoic beds of greenland, intensely arctic conditions supervened, when the inland-ice of that country extended much beyond its present limits. this was the glacial period of geologists, during which all the northern regions of america and europe, down to what are now temperate latitudes were likewise swathed in ice. various hypotheses have been advanced in explanation of these strange climatic vicissitudes, and some of them are very briefly discussed by dr. nansen. none of the suggested solutions of the problem quite satisfies him; but he appears to look with most favour on the view that great climatic revolutions in what are now polar regions may have resulted from movements of the earth's axis. he admits, however, that there are certain strong objections to this hypothesis, and concludes that we have not yet got any satisfactory explanation to cover all the facts of the case. in discussing the question of a possible wandering of the pole, the author cites certain astronomical observations to show that the position of the axis is even now slowly changing, the movement amounting to half a second in six months. this is not much; but if the change, as he remarks, were to continue at the same rate for years, the shift would amount to one degree. thus in a period of no more than , to , years greenland might be brought into the latitude required for the growth of such floras as those of cainozoic and mesozoic times. geologists will readily concede these or longer periods if they be required, but they will have graver doubts than dr. nansen as to whether any such great changes in the axis are possible. the astronomical observations referred to, even if they were fully confirmed, do not show that the movement is constant in one direction. they indicated, as he mentions, a slight increase of latitude during the first quarter of , followed in the second quarter of the same year by a decrease, which continued to january, . since the publication of professor george darwin's masterly paper on the influence of geological changes on the earth's axis of rotation, geologists have felt assured that the great climatic revolutions to which the stratified rocks bear witness must be otherwise explained than by a wandering of the pole. indeed, the geological evidence alone is enough to show that profound climatic changes have taken place while the pole has occupied its present position. thus, there is no reasonable grounds for doubting that during the glacial period the pole was just where we find it to-day. for, under existing geographical conditions, could a sufficient lowering of temperature be brought about, snow-fields and ice-sheets would gather and increase over the very same areas as we know were glaciated in pleistocene times. still further, we have only to recall the fact that several extreme revolutions of climate supervened during the so-called glacial period, to see how impossible it is to account for the phenomena by movements of the earth's axis. if it be true that the great climatic changes of the pleistocene period did not result from a wandering to and fro of the pole, then it is not at all likely that the mesozoic and cainozoic climates of greenland were induced by any such movement. but does the geological evidence justify us in believing that the climates in greenland during cretaceous and tertiary times really resembled those of egypt and southern italy? it may be strongly doubted if it does. palæontologists, like other mortals, find it hard to escape the influence of environment. they are apt to project the actual present into the past, without, perhaps, fully considering how far they are justified in doing so. because there occur in cretaceous and tertiary strata, within arctic regions, certain assemblages of plants which find their nearest representatives in southern italy and egypt, surely it is rather rash to conclude that greenland has experienced climates like those now characteristic of mediterranean lands. all that the evidence really entitles us to assume is simply that the _winter temperature_ of greenland was formerly much higher than it is now. that great caution is required in comparing past with present climatological conditions may be seen by glancing for a moment at the character of the flora which lived in europe during the interglacial phase of the pleistocene period. the plants of that period are for the most part living species, so that while dealing with these we are on safer ground than when we are treating of the floras of periods so far removed from us as those of tertiary and cretaceous times. now, in the pleistocene flora of europe we find a strange commingling of species, such as we nowhere see to-day over any equally wide area of the earth's surface. during pleistocene times many plants which are still indigenous to southern france flourished side by side in that area with species which are no longer seen in the same region; some of these last having retreated because unable to support the cold of winter, while others have retired to the mountains to escape the dryness of the summer. similar evidence is forthcoming from the pleistocene accumulations of italy, northern france, and germany. in a word, clement winters and relatively cool and humid summers permitted the wide diffusion and intimate association of plants which have now a very different distribution, temperate and southern species formerly flourishing together over vast areas of southern and central europe. and similarly we find that during the same period the regions in question were tenanted by southern and temperate forms of animal life--elephants, rhinoceroses, and hippopotamuses, together with cervine, bovine, and other forms, not a few of which are still indigenous to our continent--that ranged from the shores of the mediterranean up to our own latitudes. we cannot doubt, indeed, that the present geographical distribution of plants and animals differs markedly from anything that has yet been disclosed by the researches of geologists. the climatic conditions of our day are exceptional as compared with those of earlier times, and the occurrence in greenland of southern types of plants, therefore, does not justify us in concluding that climates like those of southern italy and egypt were ever characteristic of arctic regions. it is a low winter temperature rather than a want of great summer heat that restricts the range northward of southern floras. if greenland could be divested of its inland-ice--if its winter temperature never fell below that of our own island--it would doubtless become clothed in time with an abundant temperate flora. judging from what is known of the various floras and faunas that have successively clothed and peopled the world, from palæozoic down to the close of cainozoic times, the general climatic conditions of the globe, prior to the glacial period, would seem to have been prevalently insular rather than continental as they are now. the lands appear to have been formerly much less continuous, and ocean currents from southern latitudes had consequently freer access to high northern regions than is at present possible. in no other way can we account for the facts connected with the geographical distribution and extent of the fossiliferous formations. but are we to infer, from the occurrence of similar assemblages of marine organic remains in arctic, temperate, and tropical latitudes, that the shores of primeval greenland were washed by waters as warm as those of the tropics? surely not: an absence of very cold water in the far north is all that we seem justified in assuming. and so, in like manner, the presence in greenland of fossil floras having the same general facies as those that occur in the corresponding strata of more southern latitudes, does not compel us to believe that conditions at all similar to what are now met with in warm-temperate and sub-tropical lands ever obtained in arctic regions. a relatively high winter temperature alone would permit the range northward of many tribes of plants which are now restricted to southern latitudes. yet, under the most uniform insular climatic conditions that we can conceive of, there must always have been differences due to latitude--although such differences were never apparently so marked as they are now. in order to appreciate the character of the climate which must have prevailed when the lands of the globe were much more interrupted and insular than at present, we have only to consider how greatly isothermal lines, even under existing continental conditions, are deflected by ocean-currents. in the north atlantic, for example, the winter isotherm of ° f. is deflected northward from the parallel of new york to that of hammerfest--a displacement of at least ° of latitude. the arctic sea now occupies a partially closed basin, into which only one considerable current enters from the south. but in earlier ages the case was otherwise, and there was often communication across what are now our continental areas. instead of being girdled, as at present, by an almost continuous land-mass, the arctic sea seems to have formed with the circumjacent ocean one great archipelago. thus freely open to the influx of southern currents, it is not difficult to believe that the seas of the far north might never be frozen, and that an "inland-ice" like that of greenland would be impossible. the present cold summers of that country, as the late dr. croll has insisted, are due not so much to high latitude as to the presence of snow and ice. could these be removed, the summers would be as warm at least as those of england. now the occurrence in arctic regions of palæozoic and mesozoic marine faunas is strongly suggestive of the former presence there of genial waters having free communication with lower latitudes; and it is to the presence of these warm currents, flowing uninterruptedly through polar regions, that we would attribute the high winter temperature and uniform climate to which the fossil floras and faunas of greenland bear testimony. if these views be at all reasonable, it seems unnecessary to call to our aid hypothetical changes in the position of the earth's axis. it may be admitted, however, that the climate of the arctic regions must have been from time to time more or less affected by those cosmical causes to which croll has appealed. so long, however, as insular conditions prevailed, the changes induced by a great increase in the eccentricity of the earth's orbit would not necessarily be strongly marked. dr. nansen objects to croll's well-known theory that "it cannot account for the recurrence of conditions so favourable as to explain the existence in greenland of a climate comparable to what we now find in tropical regions." no doubt it cannot, but, as we maintain, there is no good reason for supposing that tropical or sub-tropical climates ever characterised any area within the arctic circle. the remarkable association in europe, during so recent a period as the pleistocene, of southern and temperate species of plants and animals, ought to warn us against taking the present distribution of life-forms as an exact type of the kind of distribution which characterised earlier ages. it is safe to say that were our present continental areas to become broken up into groups of larger and smaller islands, so as to allow of a much less impeded oceanic circulation, the resulting climatic conditions would offer the strongest contrast to the present. and as the lands of the globe were apparently in former times more insular than they are now, it is hazardous to compare the climates of the present with those of the past. it is reasonable to infer, from the occurrence in greenland of fossil floras which find their nearest representatives in southern europe and north africa, that the winters of the far north were formerly mild and clement. but we cannot conclude, from the same evidence, that the arctic summers were ever as hot as those of our present warm-temperate and sub-tropical zones. but if the recent expedition has thrown no new light on the disputed question as to the cause of the high temperature which formerly prevailed in greenland, it is needless to say that it has added considerably to our knowledge of the present physical conditions of that country. the view held by many that greenland must be wrapped in ice has been amply justified, and we can now no longer doubt that the inland-ice covers the whole country from the th parallel southwards. a section of greenland in the latitude at which it was crossed by nansen and his comrades "gives an almost exact mathematical curve, approximating very closely to the arc of a circle described with a radius of about miles. the whole way across the surface coincides tolerably accurately with this arc, though it falls away somewhat abruptly at the coasts, and a little more abruptly on the east side than the west." taking the observations of other arctic travellers with his own, nansen is led to the conclusion that "the surface of the inland-ice forms part of a remarkably regular cylinder, the radius of which nevertheless varies not a little at different latitudes, increasing markedly from the south, and consequently making the arc of the surface flatter and flatter as it advances northwards." he points out that this remarkable configuration must to a certain extent be independent of the form of the underlying land-surface, which, to judge from the character of the wild and mountainous coast-lands, probably resembles norway in its general configuration--if, indeed it be not a group of mountainous islands. the buried interior of greenland must in fact be a region of high mountains and deep valleys, all of which have totally disappeared under the enveloping _mer de glace_. it is obvious, as dr. nansen remarks, that the minor irregularities of the land "have had no influence whatever upon the form of the upper surface of the ice-sheet." that surface-form has simply been determined by the force of pressure--the quasi-viscous mass attaining its maximum thickness towards the central line of the country, where resistance to the movement due to pressure must necessarily have been greatest. thus although the larger features of the ice-drowned land may have had some influence in determining the position of the ice-shed, it is not by any means certain that this central line coincides with the dominant ridge or watershed of the land itself. for, as nansen reminds us, the ice-shed of the scandinavian inland-ice of glacial times certainly lay about miles to the east of the main water-parting of norway and sweden. similar facts, we may add, have been noticed in connection with the old ice-sheets of scotland and ireland. the greatest elevation attained by the expedition was feet. how deeply buried the dominating parts of the land-surface may be at that elevation one cannot tell. it is obvious, however, that the _mer de glace_ must be very unequal in thickness. according to dr. nansen the average elevation of the valleys in the interior cannot much exceed or feet, so that the ice lying above such depressions must have a thickness of to feet. it cannot, of course, lie so deeply over mountain-ridges. the eroding power of such a glacier-mass must be enormous, and dr. nansen does not doubt that the buried valleys of greenland are being widened and deepened by the grinding of the great ice-streams that are ever advancing towards the sea. the expedition met with no streams of surface-water on the inland-ice; indeed, the amount of superficial melting in the interior was quite insignificant. and yet, as is well known, many considerable streams and rivers flow out from underneath the inland-ice all the year round. it is obvious, therefore, that this water-supply does not come from superficial sources, as, according to dr. nansen, it is usually supposed to do. but surely it has long been recognised that such rivers as the mary minturn must be derived from sub-glacial melting. and the various causes to which our author attributes this melting have already frequently been pointed out. earth-heat--the influence of pressure in lowering the melting-point of ice--and the friction induced by the movement of the ice itself have all long ago been recognised as factors tending to produce the sub-glacial water-drainage of an ice-sheet. dr. nansen's speculations on the origin of the "drumlins" and "kames" of formerly glaciated areas will interest geologists, but are not so novel as he supposes. his description of what are known as "drumlins" is not quite correct. these long lenticular banks cannot be said to lie upon boulder-clay, but are merely a structural form of that accumulation. and it is hardly the case that geologists have "performed the most acrobatic feats" in trying to explain the origin of the banks in question. the usual explanation is that they have been formed underneath the ice as ground-moraine--the upper surface of which varies in configuration--being sometimes approximately even, as in broad mountain-valleys; at other times ridged and corrugated, as in open lowlands. and these modifications of surface are supposed to have resulted from the varying movement and pressure of the overlying ice-sheet. the drumlins, in fact, would appear to be analogous to the banks that accumulate in the beds of rivers. many drumlins, indeed, are composed partly of solid rock and partly of boulder-clay, which would seem to have accumulated in the lee of the projecting rock, much in the same way as gravel and sand gather behind any large boulder in a stream-course. dr. nansen, apparently, to some extent confounds drumlins with "kames" and "åsar," of which certainly many strange and conflicting explanations have been hazarded. these, however, differ essentially from drumlins, for they consist exclusively, or almost exclusively, of water-worn and more or less water-assorted materials. and one widely-accepted view of their origin is that they have accumulated in tunnels underneath an ice-sheet. this is practically the same view as dr. nansen's. he thinks that when an ice-sheet has its under-surface furrowed by running water, the ground-moraine will tend to be pressed up into the river-channels. the water will, in this way, be compelled to hollow out the roof of its tunnel to a greater degree, and as the stream continues to work upwards the moraine will follow it, so as to partially fill the tunnel and form a ridge along the back of which the sub-glacial stream will run. the material forming the upper portion of the ridge will thus come to be composed mainly of water-worn and stratified detritus, derived from the erosion of the ground-moraine. this is an ingenious suggestion which may be of good service in some cases, but it is certainly inapplicable to most kames and åsar. if it were a complete explanation we ought to find these ridges consisting of an upper water-assorted portion and a lower unmodified morainic portion (boulder-clay). but this is not the case, for most kames consist entirely, from top to bottom, of water-assorted materials. they are found running across an even or gently-undulating surface of boulder-clay, and sometimes they rest not on boulder-clay but solid rock. dr. nansen considers another geological question which has given rise to much controversy, and is still far from being settled--namely, whether the oscillations of level which have left such conspicuous traces in northern regions are in any way connected with the appearance and disappearance of great ice-sheets. can a big ice-sheet push down the earth's crust by its weight? and does the crust rise again as the ice melts away? could a thick ice-sheet exercise sufficient attraction upon the sea to cause it to rise upon the land, and thus explain the origin of some of the so-called raised beaches of this and other formerly glaciated lands? can the weight of a great ice-sheet shift the earth's centre of gravity, and, if so, to what extent? each of these questions has been answered in the affirmative and the negative by controversialists, and, until the geological evidence has been completely sifted, each, doubtless, will continue to be alternately affirmed and denied. all that need be pointed out here is that some of the movements which occurred during the pleistocene period were on much too large a scale to be explicable by any of the hypotheses referred to. xiv. the geographical development of coast-lines.[do] [do] presidential address to the geographical section of the british association, edinburgh, . amongst the many questions upon which of late years light has been thrown by deep-sea exploration and geological research, not the least interesting is that of the geographical development of coast-lines. how is the existing distribution of land and water to be accounted for? are the revolutions in the relative position of land and sea, to which the geological record bears witness, due to movements of the earth's crust or of the hydrosphere? why are coast-lines in some regions extremely regular, while elsewhere they are much indented? about years ago the prevalent belief was that ancient sea-margins indicated a formerly higher ocean-level. such was the view held by celsius, who, from an examination of the coast-lands of sweden, attributed the retreat of the sea to a gradual drying up of the latter. but this desiccation hypothesis was not accepted by playfair, who thought it much more likely that the land had risen. it was not, however, until after von buch had visited sweden ( - ), and published the results of his observations, that playfair's suggestion received much consideration. von buch concluded that the apparent retreat of the sea was not due to a general depression of the ocean-level, but to elevation of the land--a conclusion which subsequently obtained the strong support of lyell. the authority of these celebrated men gained for the elevation theory more or less complete assent, and for many years it has been the orthodox belief of geologists that the ancient sea-margins of sweden and other lands have resulted from vertical movements of the crust. it has long been admitted, however, that highly-flexed and disturbed strata require some other explanation. obviously such structures are the result of lateral compression and crumpling. hence geologists have maintained that the mysterious subterranean forces have affected the crust in different ways. mountain-ranges, they conceive, are ridged up by tangential thrusts and compression, while vast continental areas slowly rise and fall, with little or no disturbance of the strata. from this point of view it is the lithosphere that is unstable, all changes in the relative level of land and sea being due to crustal movements. of late years, however, trautschold and others have begun to doubt whether this theory is wholly true, and to maintain that the sea-level may have changed without reference to movements of the lithosphere. thus hilber has suggested that sinking of the sea-level may be due, in part at least, to absorption, while schmick believes that the apparent elevation and depression of continental areas are really the results of grand secular movements of the ocean. the sea, according to him, periodically attains a high level in each hemisphere alternately, the waters being at present heaped up in the southern hemisphere. professor suess, again, believing that in equatorial regions the sea is, on the whole, gaining on the land, while in other latitudes the reverse would appear to be the case, points out this is in harmony with his view of a periodical flux and reflux of the ocean between the equator and the poles. he thinks we have no evidence of any vertical elevation affecting wide areas, and that the only movements of elevation that take place are those by which mountains are upheaved. the broad invasions and transgressions of the continental areas by the sea, which we know have occurred again and again, are attributed by him to secular movements of the hydrosphere itself. apart from all hypothesis and theory, we learn that the surface of the sea is not exactly spheroidal. it reaches a higher level on the borders of the continents than in mid-ocean, and it varies likewise in height at different places on the same coast. the attraction of the himalaya, for example, suffices to cause a difference of feet between the level of the sea at the delta of the indus and on the coast of ceylon. the recognition of such facts has led penck to suggest that the submergence of the maritime regions of north-west europe and the opposite coasts of north america, which took place at a recent geological date, and from which the lands in question have only partially recovered, may have been brought about by the attraction exerted by the vast ice-sheets of the glacial period. but, as drygalski, woodward, and others have shown, the heights at which recent marine deposits occur in the regions referred to are much too great to be accounted for by any possible distortion of the hydrosphere. the late james croll had previously endeavoured to show that the accumulation of ice over northern lands during glacial times would suffice to displace the earth's centre of gravity, and thus cause the sea to rise upon the glaciated tracts. more recently other views have been advanced to explain the apparently causal connection between glaciation and submergence, but these need not be considered here. whatever degree of importance may attach to the various hypotheses of secular movements of the sea, it is obvious that the general trends of the world's coast-lines are determined in the first place by the position of the dominant wrinkles of the lithosphere. even if we concede that all "raised beaches," so-called, are not necessarily the result of earth-movements, and that the frequent transgressions of the continental areas by oceanic waters in geological times may possibly have been due to independent movements of the sea, still we must admit that the solid crust of the globe has always been subject to distortion. and this being so, we cannot doubt that the general trends of the world's coast-lines must have been modified from time to time by movements of the lithosphere. as geographers we are not immediately concerned with the mode of origin of those vast wrinkles, nor need we speculate on the causes which may have determined their direction. it seems, however, to be the general opinion that the configuration of the lithosphere is due simply to the sinking-in and doubling-up of the crust on the cooling and contracting nucleus. but it must be admitted that neither physicists nor geologists are prepared with a satisfactory hypothesis to account for the prominent trends of the great world-ridges and troughs. according to the late professor alexander winchell, these trends may have been the result of primitive tidal action. he was of opinion that the transmeridional progress of the tidal swell in early incrustive times on our planet would give the forming crust structural characteristics and aptitudes trending from north to south. the earliest wrinkles to come into existence, therefore, would be meridional or submeridional, and such, certainly, is the prevalent direction of the most conspicuous earth-features. there are many terrestrial trends, however, as professor winchell knew, which do not conform to the requirements of his hypothesis; but such transmeridional features, he thought, could generally be shown to be of later origin than the others. this is the only speculation, so far as i know, which attempts, perhaps not altogether unsuccessfully, to explain the origin of the main trends of terrestrial features. according to other authorities, however, the area of the earth's crust occupied by the ocean is denser than that over which the continental regions are spread. the depressed denser part balances the lighter elevated portion. but why these regions of different densities should be so distributed no one has yet told us. neither does le conte's view, that the continental areas and the oceanic depressions owe their origin to unequal radial contraction of the earth in its secular cooling, help us to understand why the larger features of the globe should be disposed as they are. geographers must for the present be content to take the world as they find it. what we do know is that our lands are distributed over the surface of a great continental plateau of irregular form, the bounding slopes of which plunge down more or less steeply into a vast oceanic depression. so far as geological research has gone, there is reason to believe that these elevated and depressed areas are of primeval antiquity--that they ante-date the very oldest of the sedimentary formations. there is abundant evidence, however, to show that the relatively elevated or continental area has been again and again irregularly submerged under tolerably deep and wide seas. but all historical geology seems to assure us that the continental plateau and the oceanic hollows have never changed places, although from time to time portions of the latter have been ridged up and added to the margins of the former, while ever and anon marginal portions of the plateau have sunk to very considerable depths. we may thus speak of the great world-ridges as regions of dominant elevation, and of the profound oceanic troughs as areas of more or less persistent depression. from one point of view, it is true, no part of the earth's surface can be looked upon as a region of dominant elevation. our globe is a cooling and contracting body, and depression must always be the prevailing movement of the lithosphere. the elevation of the continental plateau is thus only relative. could we conceive the crust throughout the deeper portions of the oceanic depression to subside to still greater depths, while at the same time the continental plateau remained stationary, or subsided more slowly, the sea would necessarily retreat from the land, and the latter would then appear to rise. it is improbable, however, that any extensive subsidence of the crust under the ocean could take place without accompanying disturbance of the continental plateau; and in this case the latter might experience in places not only negative but positive elevation. during the evolution of our continents, crustal movements have again and again disturbed the relative level of land and sea; but since the general result has been to increase the land-surface and to contract the area occupied by the sea, it is convenient to speak of the former as the region of dominant elevation, and of the latter as that of prevalent depression. properly speaking, both are sinking regions, the rate of subsidence within the oceanic trough being in excess of that experienced over the continental plateau. the question of the geographical development of coast-lines is therefore only that of the dry lands themselves. the greater land-masses are all situated upon, but are nowhere co-extensive with, the area of dominant elevation, for very considerable portions of the continental plateau are still covered by the sea. opinions may differ as to which fathoms-line we should take as marking approximately the boundary between that region and the oceanic depression; and it is obvious, indeed, that any line selected must be arbitrary and more or less misleading, for it is quite certain that the true boundary of the continental plateau cannot lie parallel to the surface of the ocean. in some regions it approaches within a few hundreds of fathoms of the sea-level; in other places it sinks for considerably more than fathoms below that level. thus, while a very moderate elevation would in certain latitudes cause the land to extend to the edge of the plateau, an elevation of at least , feet would be required in some other places to bring about a similar result. although it is true that the land-surface is nowhere co-extensive with the great plateau, yet the existing coast-lines may be said to trend in the same general direction as its margins. so abruptly does the continental plateau rise from the oceanic trough, that a depression of the sea-level, or an elevation of the plateau, for , feet, would add only a narrow belt to the pacific coast between alaska and cape horn, while the gain of land on the atlantic slope of america between ° n.l. and ° s.l. would not be much greater. in the higher latitudes of the northern hemisphere, however, very considerable geographical changes would be accomplished by a much less amount of elevation of the plateau. were the continental plateau to be upheaved for feet, the major portion of the arctic sea would become land. thus, in general terms, we may say that the coast-lines of arctic and temperate north america and eurasia are further withdrawn from the edge of the continental plateau than those of lower latitudes. in regions where existing coast-lines approach the margin of the plateau, they are apt to run for long distances in one determinate direction, and, whether the coastal area be high or not, to show a gentle sinuosity. their course is seldom interrupted by bold projecting headlands or peninsulas, or by intruding inlets, while fringing or marginal islands rarely occur. to these appearances the northern regions, as every one knows, offer the strongest contrast. not only do they trend irregularly, but their continuity is constantly interrupted by promontories and peninsulas, by inlets and fiords, while fringing islands abound. but an elevation of some or fathoms only would revolutionise the geography of those regions, and confer upon the northern coast-lines of the world the regularity which at present characterises those of western africa. it is obvious, therefore, that the coast-lines of such lands as africa owe their regularity primarily to their approximate coincidence with the steep boundary-slopes of the continental plateau, while the irregularities characteristic of the coast-line of north-western europe and the corresponding latitudes of north america are determined by the superficial configuration of the same plateau, which in those regions is relatively more depressed. i have spoken of the general contrast between high and low northern latitudes; but it is needless to say that in southern regions the coast-lines exhibit similar contrasts. the regular coast-lines of africa and south america have already been referred to; but we cannot fail to recognise in the much-indented sea-board and the numerous coastal islands of southern chile a complete analogy to the fiord regions of high northern latitudes. both are areas of comparatively recent depression. again, the manifold irregularities of the coasts of south-eastern asia, and the multitudes of islands that serve to link that continent to australia and new zealand, are all evidence that the surface of the continental plateau in those regions is extensively invaded by the sea. a word or two now as to the configuration of the oceanic trough. there can be no doubt that this differs very considerably from that of the land-surface. it is, upon the whole, flat or gently-undulating. here and there it swells gently upwards into broad elevated banks, some of which have been traced for great distances. in other places narrower ridges and abrupt mountain-like elevations diversify its surface, and project again and again above the level of the sea, to form the numerous islets of oceania. once more, the sounding-line has made us acquainted with the notable fact that numerous deep depressions--some long and narrow, others relatively short and broad--stud the floor of the great trough. i shall have occasion to refer again to these remarkable depressions, and need at present only call attention to the fact that they are especially well-developed in the region of the western pacific, where the floor of the sea, at the base of the bounding slopes of the continental plateau, sinks in places to depths of three and even of five miles below the existing coast-lines. one may further note the fact that the deepest areas of the atlantic are met with in like manner close to the walls of the plateau--a long ridge, which rises midway between the continents and runs in the same general direction as their coast-lines, serving to divide the trough of the atlantic into two parallel hollows. but, to return to our coast-lines and the question of their development, it is obvious that their general trends have been determined by crustal movements. their regularity is in direct proportion to the closeness of their approach to the margin of the continental plateau. the more nearly they coincide with the edge of that plateau, the fewer irregularities do they present; the further they recede from it, the more highly are they indented. various other factors, it is true, have played a more or less important part in their development, but their dominant trends were undoubtedly determined at a very early period in the world's history--their determination necessarily dates back, in short, to the time when the great world-ridges and oceanic troughs came into existence. so far as we can read the story told by the rocks, however, it would seem that in the earliest ages of which geology can speak with any confidence, the coast-lines of the world must have been infinitely more irregular than now. in palæozoic times, relatively small areas of the continental plateau appeared above the level of the sea. insular conditions everywhere prevailed. but as ages rolled on, wider and wider tracts of the plateau were exposed, and this notwithstanding many oscillations of level. so that one may say there has been, upon the whole, a general advance from insular to continental conditions. in other words, the sea has continued to retreat from the surface of the continental plateau. to account for this change, we must suppose that depression of the crust has been in excess within the oceanic area, and that now and again positive elevation of the continental plateau has taken place, more especially along its margins. that movements of elevation, positive or negative, have again and again affected our land-areas can be demonstrated, and it seems highly probable, therefore, that similar movements may have been experienced within the oceanic trough. two kinds of crustal movement, as we have seen, are recognised by geologists. sometimes the crust appears to rise, or, as the case may be, to sink over wide regions, without much disturbance or tilting of strata, although these are now and again more or less extensively fractured and displaced. it may conduce to clearness if we speak of these movements as regional. the other kind of crustal disturbance takes place more markedly in linear directions, and is always accompanied by abrupt folding and mashing together of strata, along with more or less fracturing and displacement. the plateau of the colorado has often been cited as a good example of regional elevation, where we have a wide area of approximately horizontal strata apparently uplifted without much rock-disturbance, while the alps or any other chain of highly-flexed and convoluted strata will serve as an example of what we may term axial or linear uplifts. it must be understood that both regional and axial movements result from the same cause--the adjustment of the solid crust to the contracting nucleus--and that the term _elevation_, therefore, is only relative. sometimes the sinking crust gets relief from the enormous lateral pressure to which it is subjected by crumpling up along lines of weakness, and then mountains of elevation are formed; at other times, the pressure is relieved by the formation of broader swellings, when wide areas become uplifted relatively to surrounding regions. geologists, however, are beginning to doubt whether upheaval of the latter kind can affect a broad continental area. probably, in most cases, the apparent elevation of continental regions is only negative. the land appears to have risen because the floor of the oceanic basin has become depressed. even the smaller plateau-like elevations which occur within some continental regions may in a similar way owe their dominance to the sinking of contiguous regions. in the geographical development of our land, movements of elevation and depression have played an important part. but we cannot ignore the work done by other agents of change. if the orographical features of the land everywhere attest the potency of plutonic agents, they no less forcibly assure us that the inequalities of surface resulting from such movements are universally modified by denudation and sedimentation. elevated plains and mountains are gradually demolished, and the hollows and depressions of the great continental plateau become slowly filled with their detritus. thus inland-seas tend to vanish, inlets and estuaries are silted up, and the land in places advances seaward. the energies of the sea, again, come in to aid those of rain and rivers, so that under the combined action of all the superficial agents of change, the irregularities of coast-lines become reduced, and, were no crustal movement to intervene, would eventually disappear. the work accomplished by those agents upon a coast-line is most conspicuous in regions where the surface of the continental plateau is occupied by comparatively shallow seas. here full play is given to sedimentation and marine erosion, while the latter alone comes into prominence upon shores that are washed by deeper waters. when the coast-lines advance to the edge of the continental plateau, they naturally trend, as we have seen, for great distances in some particular direction. should they preserve that position, undisturbed by crustal oscillation, for a prolonged period of time, they will eventually be cut back by the sea. in this way a shelf or terrace will be formed, narrow in some places, broader in others, according to the resistance offered by the varying character of the rocks. but no long inlets or fiords can result from such action. at most the harder and less readily demolished rocks will form headlands, while shallow bays will be scooped out of the more yielding masses. in short, between the narrower and broader parts of the eroded shelf or terrace a certain proportion will tend to be preserved. as the shelf is widened, sedimentation will become more and more effective, and in places may come to protect the land from further marine erosion. this action is especially conspicuous in tropical and sub-tropical regions, which are characterised by well-marked rainy seasons. in such regions immense quantities of sediment are washed down from the land to the sea, and tend to accumulate along shore, forming low alluvial flats. all long-established coast-lines thus acquire a characteristically sinuous form, and perhaps no better examples could be cited than those of western africa. to sum up, then, we may say that the chief agents concerned in the development of coast-lines are crustal movements, sedimentation, and marine erosion. all the main trends are the result of elevation and depression. considerable geographical changes, however, have been brought about by the silting up of those shallow and sheltered seas which, in certain regions, overflow wide areas of the continental plateau. throughout all the ages, indeed, epigene agents have striven to reduce the superficial inequalities of that plateau, by levelling heights and filling up depressions, and thus, as it were, flattening out the land-surface and causing it to extend. the erosive action of the sea, from our present point of view, is of comparatively little importance. it merely adds a few finishing touches to the work performed by the other agents of change. a glance at the geographical evolution of our own continent will render this sufficiently evident. viewed in detail, the structure of europe is exceedingly complicated, but there are certain leading features in its architecture which no profound analysis is required to detect. we note, in the first place, that highly-disturbed rocks of archæan and palæozoic age reach their greatest development along the north-western and western borders of our continent, as in scandinavia, the british islands, north-west france, and the iberian peninsula. another belt of similarly disturbed strata of like age traverses central europe from west to east, and is seen in the south of ireland, cornwall, north-west france, the ardennes, the thüringer-wald, the erz gebirge, the riesen gebirge, the böhmer-wald, and other heights of middle and southern germany. strata of mesozoic and cainozoic age rest upon the older systems in such a way as to show that the latter had been much folded, fractured, and denuded before they came to be covered with younger formations. north and north-east of the central belt of ancient rocks just referred to, the sedimentary strata that extend to the shores of the baltic and over a vast region in russia, range in age from palæozoic down to cainozoic times, and are disposed for the most part in gentle undulations--they are either approximately horizontal or slightly inclined. unlike the disturbed rocks of the maritime regions and of central europe, they have obviously been subjected to comparatively little folding since the time of their deposition. to the south of the primitive back-bone of central europe succeeds a region composed superficially of mesozoic and cainozoic strata for the most part, which, along with underlying palæozoic and archæan rocks, are often highly-flexed and ridged up, as in the chains of the jura, the alps, the carpathians, etc. one may say, in general terms, that throughout the whole mediterranean area archæan and palæozoic rocks appear at the surface only when they form the nuclei of mountains of elevation, into the composition of which rocks of younger age largely enter. from this bald and meagre outline of the general geological structure of europe, we may gather that the leading orographical features of our continent began to be developed at a very early period. unquestionably the oldest land-areas are represented by the disturbed archæan and palæozoic rocks of the atlantic sea-board and central europe. examination of those tracts shows that they have experienced excessive denudation. the archæan and palæozoic masses, distributed along the margin of the atlantic, are the mere wrecks of what, in earlier ages, must have been lofty regions, the mountain-chains of which may well have rivalled or even exceeded in height the alps of to-day. they, together with the old disturbed rocks of central europe, formed for a long time the only land in our area. between the ancient scandinavian tract in the north and a narrow interrupted belt in central europe, stretched a shallow sea, which covered all the regions that now form our great plain; while immediately south of the central belt lay the wide depression of the mediterranean--for as yet the pyrenees, the alps, and the carpathians were not. both the mediterranean and the russo-germanic sea communicated with the atlantic. as time went on land continued to be developed along the same lines, a result due partly to crustal movements, partly to sedimentation. thus the relatively shallow russo-germanic sea became silted up, while the mediterranean shore-line advanced southwards. it is interesting to note that the latter sea, down to the close of tertiary times, seems always to have communicated freely with the atlantic, and to have been relatively deep. the russo-germanic sea, on the contrary, while now and again opening widely into the atlantic, and attaining considerable depths in its western reaches, remained on the whole shallow, and ever and anon vanished from wide areas to contract into a series of inland-seas and large salt lakes. reduced to its simplest elements, therefore, the structure of europe shows two primitive ridges--one extending with some interruptions along the atlantic sea-board, the other traversing central europe from west to east, and separating the area of the great plain from the mediterranean basin. the excessive denudation which the more ancient lands have undergone, and the great uplifts of mesozoic and of cainozoic times, together with the comparatively recent submergence of broad tracts in the north and north-west, have not succeeded in obscuring the dominant features in the architecture of our continent. i now proceed to trace, as rapidly as i can, the geographical development of the coast-lines of the atlantic as a whole, and to point out the chief contrasts between them and the coast-lines of the pacific. the extreme irregularity of the arctic and atlantic shores of europe at once suggests to a geologist a partially-drowned land, the superficial inequalities of which are accountable for the vagaries of the coast-lines. the fiords of norway and scotland occupy what were at no distant date land-valleys, and the numerous marginal islands of those regions are merely the projecting portions of a recently-sunken area. the continental plateau extends up to and a little beyond the one hundred fathoms line, and there are many indications that the land formerly reached as far. thus the sunken area is traversed by valley-like depressions, which widen as they pass outwards to the edge of the plateau, and have all the appearance of being hollows of sub-aërial erosion. i have already mentioned the fact that the scandinavian uplands and the scottish highlands are the relics of what were at one time true mountains of elevation, corresponding in the mode of their formation to those of switzerland, and, like these, attaining a great elevation. during subsequent stages of palæozoic time, that highly-elevated region was subjected to long-continued and profound erosion--the mountain-country was planed down over wide regions to sea-level, and broad stretches of the reduced land-surface became submerged. younger palæozoic formations then accumulated upon the drowned land, until eventually renewed crustal disturbance supervened, and the marginal areas of the continental plateau again appeared as dry land, but not, as before, in the form of mountains of elevation. lofty table-lands now took the place of abrupt and serrated ranges and chains--table-lands which, in their turn, were destined in the course of long ages to be deeply sculptured and furrowed by sub-aërial agents. during this process the european coast-line would seem to have coincided more or less closely with the edge of the continental plateau. finally, after many subsequent movements of the crust in these latitudes, the land became partially submerged--a condition from which north-western and northern europe would appear in recent times to be slowly recovering. thus the highly-indented coast-line of those regions does not coincide with the edge of the plateau, but with those irregularities of its upper surface which are the result of antecedent sub-aërial erosion. mention has been made of the russo-germanic plain and the mediterranean as representing original depressions in the continental plateau, and of the high-grounds that extend between them as regions of dominant elevation, which, throughout all the manifold revolutions of the past, would appear to have persisted as a more or less well-marked boundary, separating the northern from the southern basin. during certain periods it was no doubt in some degree submerged, but never apparently to the same extent as the depressed areas it served to separate. from time to time uplifts continued to take place along this central belt, which thus increased in breadth, the younger formations, which were accumulated along the margins of the two basins, being successively ridged up against nuclei of older rocks. the latest great crustal movements in our continent, resulting in the uplift of the alps and other east and west ranges of similar age, have still further widened that ancient belt of dominant elevation which in our day forms the most marked orographical feature of europe. the russo-germanic basin is now for the most part land, the baltic and the north sea representing its still submerged portions. this basin, as already remarked, was probably never so deep as that of the mediterranean. we gather as much from the fact that, while mechanical sediments of comparatively shallow-water origin predominate in the former area, limestones are the characteristic features of the southern region. its relative shallowness helps us to understand why the northern depression should have been silted up more completely than the mediterranean. we must remember also that for long ages it received the drainage of a much more extensive land-surface than the latter--the land that sloped towards the mediterranean in palæozoic and mesozoic times being of relatively little importance. thus the crustal movements which ever and anon depressed the russo-germanic area were, in the long-run, counterbalanced by sedimentation. the uplift of the alps, the atlas, and other east and west ranges, has greatly contracted the area of the mediterranean, and sedimentation has also acted in the same direction, but it is highly probable that that sea is now as deep as, or even deeper than, it has ever been. it occupies a primitive depression in which the rate of subsidence has exceeded that of sedimentation. in many respects, indeed, this remarkable transmeridional hollow--continued eastward in the red sea, the black sea, and the aralo-caspian depression--is analogous, as we shall see, to the great oceanic trough itself. in the earlier geological periods linear or axial uplifts and volcanic action again and again marked the growth of land on the atlantic sea-board. but after palæozoic times, no great mountains of elevation came into existence in that region, while volcanic action almost ceased. in tertiary times, it is true, there was a remarkable recrudescence of volcanic activity, but the massive eruptions of antrim and western scotland, of the faröe islands and iceland, must be considered apart from the general geology of our continent. from mesozoic times onwards it was along the borders of the mediterranean depression that great mountain uplifts and volcanoes chiefly presented themselves; and as the land-surface extended southwards from central europe, and the area of the mediterranean was contracted, volcanic action followed the advancing shore-lines. the occurrence of numerous extinct and of still existing volcanoes along the borders of this inland-sea, the evidence of recent crustal movements so commonly met with upon its margins, the great irregularities of its depths, the proximity of vast axial uplifts of late geological age, and the frequency of earthquake phenomena, all indicate instability, and remind us strongly of similarly constructed and disturbed regions within the area of the vast pacific. let us now look at the arctic and atlantic coast-lines of north america. from the extreme north down to the latitude of new york the shores are obviously those of a partially-submerged region. they are of the same type as the coasts of north-western europe. we have every reason to believe also that the depression of greenland and north-east america, from which these lands have only partially recovered, dates back to a comparatively recent period. the fiords and inlets, like those of europe, are merely half-drowned land-valleys, and the continental shelf is crossed by deep hollows which are evidently only the seaward continuations of well-marked terrestrial features. such, for example, is the case with the valleys of the hudson and the st. lawrence, the submerged portions of which can be followed out to the edge of the continental plateau, which is notched by them at depths of and fathoms respectively. there is, in short, a broad resemblance between the coasts of the entire arctic and north atlantic regions down to the latitudes already mentioned. everywhere they are irregular and fringed with islands in less or greater abundance--highly-denuded and deeply-incised plateaux being penetrated by fiords, while low-lying and undulating lands that shelve gently seaward are invaded by shallow bays and inlets. comparing the american with the opposite european coasts one cannot help being struck with certain other resemblances. thus hudson bay at once suggests the baltic, and the gulf of mexico, with the caribbean sea, recalls the mediterranean. but the geological structure of the coast-lands of greenland and north america betrays a much closer resemblance between these and the opposite shores of europe than appears on a glance at the map. there is something more than a mere superficial similarity. in eastern north america and greenland, just as in western europe, no grand mountain uplifts have taken place for a prodigious time. the latest great upheavals, which were accompanied by much folding and flexing of strata, are those of the appalachian chain and of the coastal ranges extending through new england, nova scotia, and newfoundland, all of which are of palæozoic age. considerable crustal movements affected the american coast-lines in mesozoic times, and during these uplifts the strata suffered fracture and displacement, but were subjected to comparatively little folding. again, along the maritime borders of north-east america, as in the corresponding coast-lines of europe, igneous action, more or less abundant in palæozoic and early mesozoic times, has since been quiescent. from the mouth of the hudson to the straits of florida the coast-lines are composed of tertiary and quaternary deposits. this shows that the land has continued down to recent times to gain upon the sea--a result brought about partly by quiet crustal movements, but to a large extent by sedimentation, aided, on the coasts of florida, by the action of reef-building corals. although volcanic action has long ceased on the american sea-board, we note that in greenland, as in the west of scotland and north of ireland, there is abundant evidence of volcanic activity at so late a period as the tertiary. it would appear that the great plateau-basalts of those regions, and of iceland and the faröe islands, were contemporaneous, and were possibly connected with an important crustal movement. it has long been suggested that at a very early geological period europe and north america may have been united. the great thickness attained by the palæozoic rocks in the eastern areas of the latter implies the existence of a wide land-surface from which ancient sediments were derived. that old land must have extended beyond the existing coast-line, but how far we cannot tell. similarly in north-west europe, during early palæozoic times, the land probably stretched further into the atlantic than at present. but whether, as some think, an actual land-connection subsisted between the two continents it is impossible to say. some such connection was formerly supposed necessary to account for life common to the palæozoic strata of both continents, and which, as they were probably denizens of comparatively shallow water, could only have crossed from one area to another along a shore-line. it is obvious, indeed, that if the oceanic troughs in those early days were of an abysmal character, a belt of shallow water would be required to explain the geographical distribution of cosmopolitan marine life-forms. but if it be true that subsidence of the crust has been going on through all geological time, and that the land-areas have nothwithstanding continued to extend over the continental plateau, then it follows that the oceanic trough must be deeper now than it was in palæozoic times. there are, moreover, certain geological facts which seem hardly explicable on the assumption that the seas of past ages attained abysmal depths over any extensive areas. the palæozoic strata which enter so largely into the framework of our lands have much the same appearance all the world over, and were accumulated for the most part in comparatively shallow water. a petrographical description of the palæozoic mechanical sediments of europe would serve almost equally well for those of america, of asia, or of australia. take in connection with this the fact that palæozoic faunas had a very much wider range than those of mesozoic and later ages, and were characterised above all by the presence of many cosmopolitan species, and we can hardly resist the conclusion that it was the comparative shallowness of the ancient seas that favoured that wide dispersal of species, and enabled currents to distribute sediments the same in kind over such vast regions. as the oceanic area deepened and contracted, and the land-surface increased, marine faunas were gradually restricted in their range, and the cosmopolitan marine forms diminished in numbers, while sediments, gathering in separate regions, became more and more differentiated. for these and other reasons which need not be entered upon here, i see no necessity for supposing that a palæozoic atlantis connected europe with north america. the broad ridge upon which the faröe islands and iceland are founded seems to pertain as truly to the oceanic depression as the long dolphin ridge of the south atlantic. the trend of the continental plateau in high latitudes is shown, as i think, by the general direction of the coast-lines of north-western europe and east greenland, the continental shelf being submerged in those regions for a few hundred fathoms only. how the icelandic ridge came into existence, and what its age may be, we can only conjecture. it may be a wrinkle as old as the oceanic trough which it traverses, or its origin may date back to a much more recent period. we may conceive it to be an area which has subsided more slowly than the floor of the ocean to the north and south; or, on the other hand, it may be a belt of positive elevation. perhaps the latter is the more probable supposition, for it seems very unlikely that crustal disturbances, resulting in axial and regional uplifts, should have been confined to the continental plateau only. be that as it may, there is little doubt that land-connection did obtain between greenland and europe in the cainozoic times along this icelandic ridge, for relics of the same tertiary flora are found in scotland, the faröe islands, iceland, and greenland. the deposits in which these plant-remains occur are associated with great sheets of volcanic rocks, which in the faröe islands and iceland reach a thickness of many thousand feet. of the same age are the massive basalts of jan mayen, spitzbergen, franz-joseph land, and greenland. these lavas seem seldom to have issued from isolated foci in the manner of modern eruptions, but rather to have welled up along the lines of rectilineal fissures. from the analogy of similar phenomena in other parts of the world it might be inferred that the volcanic action of these northern regions may have been connected with a movement of elevation, and that the icelandic ridge, if it did not come into existence during the tertiary period, was at all events greatly upheaved at that time. it would seem most likely, in short, that the volcanic action in question was connected mainly with crustal movements in the oceanic trough. similar phenomena, as is well known, are met with further south in the trough of the atlantic. thus the volcanic azores rise like iceland from the surface of a broad ridge which is separated from the continental plateau by wide and deep depressions. and so again, from the back of the great dolphin ridge, spring the volcanic islets of st. paul's, ascension, and tristan d'acunha. i have treated of the icelandic bank at some length for the purpose of showing that its volcanic phenomena do not really form an exception to the rule that such eruptions ceased after palæozoic or early mesozoic times to disturb the atlantic coast-lines of europe and north america. as the bank in question extends between greenland and the british islands, it was only natural that both those regions should be affected by its movements. but its history pertains essentially to that of the atlantic trough; and it seems to show us how transmeridional movements of the crust, accompanied by vast discharges of igneous rock, may come in time to form land-connections between what are now widely-separated areas. let us next turn our attention to the coast-lines of the gulf of mexico and the caribbean sea. these enclosed seas have frequently been compared to the mediterranean, and the resemblance is self-evident. indeed, it is so close that one may say the mexican-caribbean sea and the mediterranean are rather homologous than simply analogous. the latter, as we have seen, occupies a primitive depression, and formerly covered a much wider area. it extended at one time over much of southern europe and northern africa, and appears to have had full communication across asia minor with the indian ocean, and with the arctic ocean athwart the low-lying tracts of north-western asia. similarly, it would seem, the mexican-caribbean sea is the remaining portion of an ancient inland-sea which formerly stretched north through the heart of north america to the arctic ocean. like its european parallel, it has been diminished by sedimentation and crustal movements. it resembles the latter also in the greatness and irregularity of its depths, and in the evidence which its islands supply of volcanic action as well as of very considerable crustal movements within recent geological times. along the whole northern borders of the gulf of mexico the coast-lands, like those on the atlantic sea-board of the southern states, are composed of tertiary and recent accumulations, and the same is the case with yucatan; while similar young formations are met with on the borders of the caribbean sea and in the antilles. the bahamas and the windward islands mark out for us the margin of the continental plateau, which here falls away abruptly to profound depths. one feels assured that this portion of the plateau has been ridged up to its present level at no distant geological date. but notwithstanding all the evidence of recent extensive crustal movements in this region, it is obvious that the mexican-caribbean depression, however much it may have been subsequently modified, is of primitive origin.[dp] [dp] professor suess thinks it is probable that the caribbean sea and the mediterranean are portions of one and the same primitive depression which traversed the atlantic area in early cretaceous times. he further suggests that it may have been through the gradual widening of the central mediterranean that the atlantic in later times came into existence. before we leave the coast-lands of north america, i would again point out their leading geological features. in a word, then, they are composed for the most part of archæan and palæozoic rocks; no great linear or axial uplifts marked by much flexure of strata have taken place in those regions since palæozoic times; while igneous action virtually ceased about the close of the palæozoic or the commencement of the mesozoic period. it is not before we reach the shores of the southern states and the coast-lands of the mexican-caribbean sea that we encounter notable accumulations of mesozoic, tertiary, and younger age. these occur in approximately horizontal positions round the gulf of mexico; but in the sierra nevada of northern colombia and the cordilleras of venezuela the tertiary strata enter into the formation of true mountains of elevation. thus the mexican-caribbean depression, like that of the mediterranean, is characterised not only by its irregular depths and its volcanic phenomena, but by the propinquity of recent mountains of upheaval, which bear the same relation to the caribbean sea as the mountains of north africa do to the mediterranean. we may now compare the atlantic coasts of south america with those of africa. the former coincide in general direction with the edge of the continental plateau, to which they closely approach between cape st. roque and cape frio. in the north-east, between cape paria, opposite trinidad, and cape st. roque, the continental shelf attains a considerably greater breadth, while south of cape frio it gradually widens until, in the extreme south, it runs out towards the east in the form of a narrow ridge, upon the top of which rise the falkland islands and south georgia. excluding from consideration for the present all recent alluvial and tertiary deposits, we may say that the coast-lands from venezuela down to the south of brazil are composed principally of archæan rocks; the eastern borders of the continent further south being formed of quaternary and tertiary accumulations. so far as we know, igneous rocks are of rare occurrence on the atlantic sea-board. palæozoic strata approach the coast-lands at various points between the mouths of the amazons and la plata, and these, with the underlying and surrounding archæan rocks, are more or less folded and disturbed, while the younger strata of mesozoic and cainozoic age (occupying wide regions in the basin of the amazons, and here and there fringing the sea-coast) occur in approximately horizontal positions. it would appear, therefore, that no great axial uplifts have taken place in those regions since palæozoic times. the crustal movements of later ages were regional rather than axial; the younger rocks are not flexed and mashed together, and their elevation (negative or positive) does not seem to have been accompanied by conspicuous volcanic action. the varying width of the continental shelf is due to several causes. the orinoco, the amazons, and other rivers descending to the north-east coast, carry enormous quantities of sediment, much of which comes to rest on the submerged slopes of the continental plateau, so that the continental shelf tends to extend seawards. the same process takes place on the south-east coast, where the rio de la plata discharges its muddy waters. south of latitude ° s., however, another cause has come into play. from the mouth of the rio negro to the terminal point of the continent the whole character of the coast betokens a geologically recent emergence, accompanied and followed by considerable marine erosion. so that in this region the continental shelf increases in width by the retreat of the coast-line, while in the north-east it gains by advancing seawards. it is to be noted, however, that even there, in places where the shores are formed of alluvia, the sea tends to encroach upon the land. the atlantic coast of africa resembles that of south america in certain respects, but it also offers some important contrasts. as the northern coasts of venezuela and colombia must be considered in relation rather to the caribbean depression than to the atlantic, so the african sea-board between cape spartel and cape nun pertains structurally to the mediterranean region. from the southern limits of morocco to cape colony the coastal heights are composed chiefly of archæan and palæozoic rocks, the low shore-lands showing here and there strata of mesozoic and tertiary age together with still more recent deposits. the existing coast-lines everywhere advance close to the edge of the continental plateau, so that the submarine shelf is relatively narrower than that of eastern south america. the african coast is still further distinguished from that of south america by the presence of several groups of volcanic islands--fernando po and others in the gulf of guinea, and cape verde and canary islands. the last-named group, however, notwithstanding its geographical position, is probably related rather to the mediterranean depression than to the atlantic trough. the geological structure of the african coast-lands shows that the earliest to come into existence were those that extend between cape nun and the cape of good hope. the coastal ranges of that section are much denuded, for they are of very great antiquity, having been ridged up in palæozoic times. the later uplifts (negative or positive) of the same region were not attended by tilting and folding of strata, for the mesozoic and tertiary deposits, like those of south america, lie in comparatively horizontal positions. between cape nun and cape spartel the rocks of the maritime tracts range in age from palæozoic to cainozoic, and have been traced across morocco into algeria and tunis. they all belong to the mediterranean region, and were deposited at a time when the southern shores of that inland sea extended from a point opposite the canary islands along what is now the southern margin of morocco, algeria, and tunis. towards the close of the tertiary period the final upheaval of the atlas took place, and the mediterranean, retreating northwards, became an almost land-locked sea. i need hardly stop to point out how the african coast-lines have been modified by marine erosion and the accumulation of sediment upon the continental shelf. the extreme regularity of the coasts is due partly to the fact that the land is nearly co-extensive with the continental plateau, but it also results in large measure from the extreme antiquity of the land itself. this has allowed of the cutting-back of headlands and the rilling up of bays and inlets, a process which has been going on between morocco and cape colony with probably little interruption for a very prolonged period of time. we may note also the effect of the heavy rains of the equatorial region in washing down detritus to the shores, and in this way protecting the land to some extent from the erosive action of the sea. what now, let us ask, are the outstanding features of the coast-lines of the atlantic ocean? we have seen that along the margins of each of the bordering continents the last series of great mountain-uplifts took place in palæozoic times. this is true alike for north and south america, for europe and africa. later movements which have added to the extent of land were not marked by the extreme folding of strata which attended the early upheavals. the mesozoic and cainozoic rocks, which now and again form the shore-lands, occur in more or less undisturbed condition. the only great linear uplifts or true mountains of elevation which have come into existence in western europe and northern africa since the palæozoic period trend approximately at right angles to the direction of the atlantic trough, and are obviously related to the primitive depression of the mediterranean. the pyrenees and the atlas, therefore, although their latest elevation took place in tertiary times, form no exceptions to the rule that the extreme flexing and folding of strata which is so conspicuous a feature in the geological structure of the atlantic sea-board dates back to the palæozoic era. and the same holds true of north and south america. there all the coastal ranges of highly flexed and folded strata are of palæozoic age. the cordilleras of venezuela are no doubt a tertiary uplift, but they are as obviously related to the caribbean depression as the atlas ranges are to that of the mediterranean. again, we note that volcanic activity along the borders of the atlantic was much less pronounced during the mesozoic period than it appears to have been in the earlier ages. indeed, if we except the great tertiary basalt-flows of the icelandic ridge and the arctic regions, we may say that volcanic action almost ceased after the palæozoic era to manifest itself upon the atlantic coast-lands of north america and europe. but while volcanic action has died out upon the atlantic margins of both continents, it has continued during a prolonged geological period within the area of the mediterranean depression. and in like manner the corresponding depression between north and south america has been the scene of volcanic disturbances from mesozoic down to recent times. along the african coasts the only displays of recent volcanic action that appertain to the continental margin are those of the gulf of guinea and the cape de verde islands. the canary islands and madeira may come under the same category, but, as we have seen, they appear to stand in relationship to the mediterranean depression and the tertiary uplift of north africa. of iceland and the azores i have already spoken, and of ascension and the other volcanic islets of the south atlantic it is needless to say that they are related to wrinkles in the trough of the ocean, and therefore have no immediate connection with the continental plateau. thus in the geographical development of the atlantic coast-lines we may note the following stages:--_first_, in palæozoic times the formation of great mountain-uplifts, frequently accompanied by volcanic action. _second_, a prolonged stage of comparative coastal tranquillity, during which the maritime ranges referred to were subject to such excessive erosion that they were planed down to low levels, and in certain areas even submerged. _third_, renewed elevation (negative or positive) whereby considerable portions of the much-denuded archæan and palæozoic rocks, now largely covered by younger deposits, were converted into high-lands. during this stage not much rock-folding took place, nor were any true mountains of elevation formed parallel to the atlantic margins. it was otherwise, however, in the mediterranean and caribbean depressions, where coastal movements resulted in the formation of enormous linear uplifts. moreover, volcanic action is now and has for a long time been more characteristic of these depressions than of the atlantic coast-lands. i must now ask you to take a comprehensive glance at the coast-lines of the pacific ocean. in some important respects these offer a striking contrast to those we have been considering. time will not allow me to enter into detailed description, and i must therefore confine attention to certain salient features. examining first the shores of the americas, we find that there are two well-marked regions of fiords and fringing islands--namely, the coasts of alaska and british columbia, and of south america from ° s.l. to cape horn. although these regions may be now extending seawards in places, it is obvious that they have recently been subject to submergence. when the fiords of alaska and british columbia existed as land-valleys it is probable that a broad land-connection obtained between north america and asia. the whole pacific coast is margined by mountain-ranges, which in elevation and boldness far exceed those of the atlantic sea-board. the rocks entering into their formation range in age from archæan and palæozoic down to cainozoic, and they are almost everywhere highly disturbed and flexed. it is not necessary, even if it were possible, to consider the geological history of all those uplifted masses. it is enough for my purpose to note the fact that the coastal ranges of north america and the principal chain of the andes were all elevated in tertiary times. it may be remarked further that, from the mesozoic period down to the present, the pacific borders of america have been the scene of volcanic activity far in excess of what has been experienced on the atlantic sea-board. geographically the asiatic coasts of the pacific offer a strong contrast to those of the american borders. the latter, as we have seen, are for the most part not far removed from the edge of the continental plateau. the coasts of the mainland of asia, on the other hand, retire to a great distance, the true margin of the plateau being marked out by that great chain of islands which extends from kamchatka south to the philippines and new guinea. the seas lying between those islands and the mainland occupy depressions in the continental plateau. were that plateau to be lifted up for or feet the seas referred to would be enclosed by continuous land, and all the principal islands of the east indian archipelago--sumatra, java, celebes, and new guinea, would become united to themselves as well as to australia and new zealand. in short, it is the relatively depressed condition of the continental plateau along the western borders of the pacific basin that causes the asiatic coast-lines to differ so strikingly from those of america. from a geological point of view the differences are less striking than the resemblances. it is true that we have as yet a very imperfect knowledge of the geological structure of eastern asia, but we know enough to justify the conclusion that in its main features that region does not differ essentially from western north america. during mesozoic and cainozoic times the sea appears to have overflowed vast tracts of manchooria and china, and even to have penetrated into what is now the great desert of gobi. subsequent crustal movements revolutionised the geography of all those regions. great ranges of linear uplifts came into existence, and in these the younger formations, together with the foundations on which they rested, were squeezed into folds and ridged up against the nuclei of palæozoic and archæan rocks which had hitherto formed the only dry land. the latest of these grand upheavals are of tertiary age, and, like those of the pacific slope of america, they were accompanied by excessive volcanic action. the long chains of islands that flank the shores of asia we must look upon as a series of partially submerged or partially emerged mountain-ranges, analogous geographically to the coast-ranges of north and central america, and to the youngest cordilleras of south america. the presence of numerous active and recently extinct volcanoes, taken in connection with the occurrence of many great depressions which furrow the floor of the sea in the east indian archipelago, and the profound depths attained by the pacific trough along the borders of japan and the kurile and aleutian islands--all indicate conditions of very considerable instability of the lithosphere. we are not surprised, therefore, to meet with much apparently conflicting evidence of elevation and depression in the coast-lands of eastern asia, where in some places the sea would seem to be encroaching, while in other regions it is retreating. in all earthquake-ridden and volcanic areas such irregular coastal changes may be looked for. so extreme are the irregularities of the sea-floor in the area lying between australia, the solomon islands, the new hebrides, and new zealand, and so great are the depths attained by many of the depressions, that the margins of the continental plateau are harder to trace here than anywhere else in the world. the bottom of the oceanic trough throughout a large portion of the southern and western pacific is, in fact, traversed by many great mountain-ridges, the summits of which approach the surface again and again to form the numerous islets of polynesia. but notwithstanding the considerable depths that separate australia from new zealand there is geological evidence to show that a land-connection formerly linked both to asia. the continental plateau, therefore, must be held to include new caledonia and new zealand. hence the volcanic islets of the solomon and new hebrides groups are related to australia in the same way as the liu-kiu, japanese, and kurile islands are to asia. having rapidly sketched the more prominent features of the pacific coast-lines, we are in a position to realise the remarkable contrast they present to the coast-lines of the atlantic. the highly-folded strata of the atlantic sea-board are the relics of great mountains of upheaval, the origin of which cannot be assigned to a more recent date than palæozoic times. during subsequent crustal movements no mountains of corrugated strata were uplifted along the atlantic margins, the mesozoic and cainozoic strata of the coastal regions showing little or no disturbance. it is quite in keeping with all this that volcanic action appears to have been most strongly manifested in palæozoic times. so many long ages have passed since the upheaval of the archæan and palæozoic mountains of the atlantic sea-board that these heights have everywhere lost the character of true mountains of elevation. planed down to low levels, partially submerged and covered to some extent by newer formations, they have in many places been again converted into dry lands, forming plateaux--now sorely denuded and cut up into mountains and valleys of erosion. why the later movements along the borders of the atlantic basin should not have resulted in the wholesale plication of the younger sedimentary rocks is a question for geologists. it would seem as if the atlantic margins had reached a stage of comparative stability long before the grand tertiary uplifts of the pacific borders had taken place; for, as we have seen, the mesozoic and the cainozoic strata of the atlantic coast-lands show little or no trace of having been subjected to tangential thrusting and crushing. hence one cannot help suspecting that the retreat of the sea during mesozoic and cainozoic ages may have been due rather to subsidence of the oceanic trough and to sedimentation within the continental area than to positive elevation of the land. over the pacific trough, likewise, depression has probably been in progress more or less continuously since palæozoic times, and this movement alone must have tended to withdraw the sea from the surface of the continental plateau in asia and america. but by far the most important coastal changes in those regions have been brought about by the crumpling-up of the plateau, and the formation of gigantic mountains of upheaval along its margins. from remotest geological periods down almost to the present, the land-area has been increased from time to time by the doubling-up and consequent elevation of coastal accumulations, and by the eruption of vast masses of volcanic materials. it is this long-continued activity of the plutonic forces within the pacific area which has caused the coast-lands of that basin to contrast so strongly with those of the atlantic. the latter are incomparably older than the former--the heights of the atlantic borders being mountains of denudation of vast geological antiquity, while the coastal ranges of the pacific slope are creations but of yesterday as it were. it may well be that those cordilleras and mountain-chains reach a greater height than was ever attained by any palæozoic uplifts of the atlantic borders. but the marked disparity in elevation between the coast-lands of the pacific and the atlantic is due chiefly to a profound difference in age. had the pacific coast-lands existed for as long a period and suffered as much erosion as the ancient rocks of the atlantic sea-board, they would now have little elevation to boast of. the coast-lines of the indian ocean are not, upon the whole, far removed from the margin of the continental plateau. the elevation of east africa for feet would add only a narrow belt to the land. this would still leave madagascar an island, but there are geological reasons for concluding that this island was at a far distant period united to africa, and it must therefore be considered as forming a portion of the continental plateau. the great depths which now separate it from the mainland are probably due to local subsidence, connected with volcanic action in madagascar itself and in the comoro islands. the southern coasts of asia, like those of east africa, approach the edge of the continental plateau, so that an elevation of feet would make little addition to the land-area. with the same amount of upheaval, however, the malay peninsula, sumatra, java, and west australia would become united, but without extending much further seawards. land-connection, as we know, existed in mesozoic times between asia, australia, and new zealand, but the coast-lines of that distant period must have differed considerably from those that would appear were the regions in question to experience now a general elevation. the archæan and the palæozoic rocks of the malay peninsula and sumatra are flanked on the side of the indian ocean by great volcanic ridges, and by uplifts of tertiary strata, which continue along the line of the nicobar and the andaman islands into burma. thus the coast-lines of that section of the indian ocean exhibit a geographical development similar to that of the pacific sea-board. elsewhere, as in hindustan, arabia, and east africa, the coast-lines appear to have been determined chiefly by regional elevations of the land or subsidence of the oceanic trough in mesozoic and cainozoic times, accompanied by the out-welling of enormous floods of lava. seeing, then, that the pacific and the indian oceans are pre-eminently regions which, down to a recent date, have been subject to great crustal movements and to excessive volcanic action, we may infer that in the development of their coast-lines the sea played a very subordinate part. the shores, indeed, are largely protected from marine erosion by partially emerged volcanic ridges and by coral islands and reefs, and to a considerable extent also by the sediment which in tropical regions especially is swept down to the coast in great abundance by rains and rivers. moreover, as the geological structure of these regions assures us, the land would appear seldom to have remained sufficiently long at one level to permit of much destruction by waves and tidal currents. in fine, then, we arrive at the general conclusion that the coast-lines of the globe are of very unequal age. those of the atlantic were determined as far back as palæozoic times by great mountain-up lifts along the margin of the continental plateau. since the close of that period many crustal oscillations have taken place, but no grand mountain-ranges have again been ridged up on the atlantic sea-board. meanwhile the palæozoic mountain-chains, as we have seen, have suffered extensive denudation, have been planed down to sea-level, and even submerged. subsequently converted into land, wholly or partially as the case may have been, they now present the appearance of plains and plateaux of erosion, often deeply indented by the sea. no true mountains of elevation are met with anywhere in the coast-lands of the atlantic, while volcanic action has well-nigh ceased. in short, the atlantic margins have reached a stage of comparative stability. the trough itself, however, is traversed by at least two well-marked banks of upheaval--the great meridional dolphin ridge, and the approximately transmeridional faröe-icelandic belt--both of them bearing volcanic islands. but while all the coast-lands of the atlantic proper attained relative stability at an early period, those of the mediterranean and caribbean depressions have up to recent times been the scenes of great crustal disturbance. gigantic mountain-chains were uplifted along their margins at so late a period as the tertiary, and their shores still witness volcanic activity. it is upon the margins and within the trough of the pacific ocean, however, that subterranean action is now most remarkably developed. the coast-lines of that great basin are everywhere formed of grand uplifts and volcanic ranges, which, broadly speaking, are comparable in age to those of the mediterranean and caribbean depressions. along the north-eastern margin of the indian ocean the coast-lines resemble those of the pacific, being of like recent age, and similarly marked by the presence of numerous volcanoes. the northern and western shores, however (as in hindustan, arabia, and east africa), have been determined rather by regional elevation or by subsidence of the ocean-floor than by axial uplifts--the chief crustal disturbances dating back to an earlier period than those of the east indian archipelago. it is in keeping with this greater age of the western and northern coast-lands of the indian ocean that volcanic action is now less strongly manifested in their vicinity. i have spoken of the comparative stability of the earth's crust within the atlantic area as being evidenced by the greater age of its coastal ranges and the declining importance of its volcanic phenomena. this relative stability is further shown by the fact that the atlantic sea-board is not much disturbed by earthquakes. this, of course, is what might have been expected, for earthquakes are most characteristic of volcanic regions and of those areas in which mountain-uplifts of recent geological age occur. hence the coast-lands of the pacific and the east indies, the borders of the caribbean sea, the volcanic ridges of the atlantic basin, the lands of the mediterranean, the black sea, and the aralo-caspian depressions, the shores of the red sea, and vast tracts of southern asia, are the chief earthquake regions of the globe. it may be noted, further, that shocks are not only most frequent but most intense in the neighbourhood of the sea. they appear to originate sometimes in the volcanic ridges and coastal ranges, sometimes under the floor of the sea itself. now earthquakes, volcanoes, and uplifts are all expressions of the one great fundamental fact that the earth is a cooling and contracting body, and they indicate the lines of weakness along which the enormous pressures and strains induced by the subsidence of the crust upon its nucleus find relief. we cannot tell why the coast-lands of the atlantic should have attained at so early a period a stage of relative stability--why no axial uplifts should have been developed along their margins since palæozoic times. it may be that relief has been found in the wrinkling-up of the floor of the oceanic trough, and consequent formation of the dolphin ridge and other great submarine foldings of the crust; and it is possible that the growth of similar great ridges and wrinkles upon the bed of the pacific may in like manner relieve the coast-lands of that vast ocean, and prevent the formation of younger uplifts along their borders. i have already remarked that two kinds of elevatory movements of the crust are recognised by geologists--namely, axial and regional uplifts. some, however, are beginning to doubt, with professor suess, whether any vast regional uplifts are possible. yet the view that would attribute all such apparent elevations of the land to subsidence of the crust under the great oceanic troughs is not without its difficulties. former sea-margins of very recent geological age occur in all latitudes, and if we are to explain these by sub-oceanic depression, this will compel us to admit, as suess has remarked, a general lowering of the sea-level of upwards of feet. but it is difficult to believe that the sea-floor could have subsided to such an extent in recent times. suess thinks it is much more probable that the high-level beaches of tropical regions are not contemporaneous with those of higher latitudes, and that the phenomena are best explained by his hypothesis of a secular movement of the ocean--the water being, as he contends, alternately heaped up at the equator and the poles. the strand-lines in high latitudes, however, are certainly connected with glaciation in some way not yet understood; and if it cannot be confidently affirmed that they indicate regional movements of the land, the evidence, nevertheless, seems to point in that direction. in concluding this imperfect outline-sketch of a large subject, i ought perhaps to apologise for having trespassed so much upon the domains of geology. but in doing so i have only followed the example of geologists themselves, whose divagations in territories adjoining their own are naturally not infrequent. from much that i have said, it will be gathered that with regard to the causes of many coastal changes we are still groping in the dark. it seems not unlikely, however, that as light increases we may be compelled to modify the view that all oscillations of the sea-level are due to movements of the lithosphere alone. that is a very heretical suggestion; but that a great deal can be said for it any one will admit after a candid perusal of suess's monumental work, _das antlitz der erde_. [illustration: plate vi bathy-hypsometrical map of the world note _the map is coloured to show the surface relief of the globe without water in the ocean basins._ explanation of colouring _the colouring is graded from the darkest tint at the highest level to the lightest tint on the lowest._ the edinburgh geographical institute j. g. bartholomew f.r.g.s. ] edinburgh printed by st giles' printing company, york place. the end. other works by professor james geikie. +-----------------------------------------------------------------+ | =the great ice age.= (new edition in preparation.) | | medium vo. maps and illustrations. price, s. | | | | =prehistoric europe=: a geological sketch. | | demy vo. maps and illustrations. price, s. | | | | =outlines of geology=: for junior students and general readers. | | post vo. illustrations. price, s. | | | | =songs and lyrics, by heinrich heine and other | | german poets=; done into english verse. price, s. | +-----------------------------------------------------------------+ * * * * * transcriber's note hyphenation was not standardized. the section labeled "explanation of plate iii." 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a. to judge c. c. baldwin president of the western reserve historical society cleveland this volume is dedicated in recognition of his sagacious and unfailing interest in the investigations which have made it possible preface to the second edition. since, as stated in the introduction (page ), the plan of this volume permitted only "a concise presentation of the facts," it was impossible to introduce either full references to the illimitable literature of the subject or detailed discussion of all disputed points. the facts selected, therefore, were for the most part those upon which it was supposed there would be pretty general agreement. the discussion upon the subject of the continuity of the glacial period was, however, somewhat elaborate (see pages - , , , ), and was presented with excessive respect for the authority of those who maintain the opposite view; all that was claimed (page ) being that one might maintain the _unity_ or _continuity_ of the glacial period "without forfeiting his right to the respect of his fellow-geologists." but it already appears that there was no need of this extreme modesty of statement. on the contrary, the vigorous discussion of the subject which has characterized the last two years reveals a decided reaction against the theory that there has been more than one glacial epoch in quaternary times; while there have been brought to light many most important if not conclusive facts in favour of the theory supported in the volume. in america the continuity of the glacial period has been maintained during the past two years with important new evidence, among others by authorities of no less eminence and special experience in glacial investigations than professor dana,[a] mr. warren upham,[b] and professor edward h. williams, jr.[c] professor williams's investigations on the attenuated border of the glacial deposits in the lehigh, the most important upper tributary to the delaware valley, pa., are of important significance, since the area which he so carefully studied lies wholly south of the terminal moraine of lewis and wright, and belongs to the portion of the older drift which professors chamberlin and salisbury have been most positive in assigning to the first glacial epoch, which they have maintained was separated from the second epoch by a length of time sufficient for the streams to erode rock gorges in the delaware and lehigh rivers from two hundred to three hundred feet in depth.[d] but professor williams has found that the rock gorges of the lehigh, and even of its southern tributaries, had been worn down approximately to the present depth of that of the delaware before this earliest period of glaciation, and that the gorges were filled with the earliest glacial _débris_. [footnote a: american journal of science, vol. xlvi, pp. , .] [footnote b: american journal of science, vols, xlvi, pp. - ; xlvii, pp. - ; american geologist, vols, x, pp. - , especially pp. , ; xiii, pp. , ; bulletin of the geological society of america, vol. v, pp. - , - .] [footnote c: bulletin of the geological society of america, vol. v, pp. - , - ; american journal of science, vol. xlvii, pp. - .] [footnote d: see especially chamberlin, in the american journal of science, vol. xlv, p. ; salisbury, in the american geologist, vol. xi, p. .] a similar relation of the glacial deposits of the attenuated border to the preglacial erosion of the rock gorges of the alleghany and upper ohio rivers has been brought to light by the joint investigations of mr. frank leverett and myself in western pennsylvania, in the vicinity of warren, pa., where, in an area which was affected by only the earliest glaciation, glacial deposits are found filling the rock channels of old tributaries to the alleghany to a depth of from one hundred and seventy to two hundred and fifty feet, and carrying the preglacial erosion at that point very closely, if not quite, down to the present rock bottoms of all the streams. this removes from professor chamberlin a most important part of the evidence of a long interglacial period to which he had appealed; he having maintained[e] that "the higher glacial gravels antedated those of the moraine-forming epoch by the measure of the erosion of the channel through the old drift and the rock, whose mean depth here is about three hundred feet, of which perhaps two hundred and fifty feet may be said to be rock," adding that the "excavation that intervened between the two epochs in other portions of the alleghany, monongahela, and upper ohio valleys is closely comparable with this." [footnote e: bulletin of the united states geological survey, p. ; american journal of science, vol. xlv, p. .] these observations of mr. leverett and myself seem to demonstrate the position maintained in the volume (page ), namely, that the inner precipitous rock gorges of the upper ohio and its tributaries are mainly _pre_glacial, rather than _inter_glacial. the only way in which professor chamberlin can in any degree break the force of this discovery is by assuming that in preglacial times the present narrow rock gorges of the alleghany and the ohio were not continuous, but that (as indicated in the present volume on page ) the drainage of various portions of that region was by northern outlets to the lake erie basin, leaving, on this supposition, the _cols_ between two or three drainage areas to be lowered in glacial or interglacial time. on the theory of continuity the erosion of these _cols_ would have been rapidly effected by the reversed drainage consequent upon the arrival of the ice-front at the southern shore of the lake erie basin. during all the time elapsing thereafter, until the ice had reached its southern limit, the stream was also augmented by the annual partial melting of the advancing glacier which was constantly bringing into the valley the frozen precipitation of the far north. the distance is from thirty to seventy miles, so that a moderately slow advance of the ice at that stage would afford time for a great amount of erosion before sufficient northern gravel had reached the region to begin the filling of the gorge.[f] [footnote f: see an elaborate discussion of the subject in its new phases by chamberlin and leverett, in the american journal of science, vol. xlvii, pp. - .] mr. leverett also presented an important paper before the geological society of america at its meeting at madison, wis., in august, , adducing evidence which, he thinks, goes to prove that the post-glacial erosion in the earlier drift in the region of rock river, ill., was seven or eight times as much as that in the later drift farther north; while mr. oscar h. hershey arrives at nearly the same conclusions from a study of the buried channels in northwestern illinois.[g] but even if these estimates are approximately correct--which is by no means certain--they only prove the length of the glacial period, and not necessarily its discontinuity. [footnote g: american geologist, vol. xii, p. f. other important evidence to a similar effect is given by mr. leverett, in an article on the glacial succession in ohio, journal of geology, vol. i, pp. - .] at the same time it should be said that these investigations in western pennsylvania somewhat modify a portion of the discussion in the present volume concerning the effects of the cincinnati ice-dam. it now appears that the full extent of the gravel terraces of glacial origin in the alleghany river had not before been fully appreciated, since they are nearly continuous on the two-hundred-foot rock shelf, and are often as much as eighty feet thick. it seems probable, therefore, that the alleghany and upper ohio gorge was filled with glacial gravel to a depth of about two hundred and fifty or three hundred feet, as far down at least as wheeling, w. va. if this was the case, it would obviate the necessity of bringing in the cincinnati ice-dam (as set forth in pages - ) to account directly for all the phenomena in that region, except as this obstruction at cincinnati would greatly facilitate the silting up of the gorge. the simple accumulation of glacial gravel in the alleghany gorge would of itself dam up the monongahela at pittsburg, so as to produce the results detailed by professor white on page .[h] [footnote h: for a full discussion of these topics, see paper by professor b. c. jillson, transactions of the academy of science and art of pittsburg, december , ; g. f. wright, american journal of science, vol. xlvii, pp. - ; especially pp. , ; the popular science monthly, vol. xlv, pp. - .] of european authorities who have recently favoured the theory of the continuity of the quaternary glacial period, as maintained in the volume, it is enough to mention the names of prestwich,[i] hughes,[j] kendall,[k] lamplugh,[l] and wallace,[m] of england; falsan,[n] of france; holst,[o] of sweden; credner[p] and diener,[q] of germany; and nikitin[r] and kropotkin,[s] of russia.[t] among leading authorities still favouring a succession of glacial epochs are: professor james geikie,[u] of scotland; baron de geer,[v] of sweden; and professor felix wahnschaffe,[w] of germany. [footnote i: quarterly journal of the geological society for august, .] [footnote j: american geologist, vol. viii, p. .] [footnote k: transactions of the leeds geological association for february , .] [footnote l: quarterly journal of the geological society, august, .] [footnote m: fortnightly review, november, , p. ; reprinted in the popular science monthly, vol. xliv, p. .] [footnote n: la période glaciaire (félix alcan. paris, ).] [footnote o: american geologist, vol. viii, p. .] [footnote p: ibid., p. .] [footnote q: ibid., p. .] [footnote r: congrès international d'archéologie, moscow, .] [footnote s: nineteenth century, january, , p. , note.] [footnote t: the volume the glacial geology of great britain and ireland, edited from the unpublished mss. of the late henry carvill lewis (london, longmans, green & co., ), adds much important evidence in favour of the continuity of the glacial epoch; see especially pp. , , , .] [footnote u: transactions of the royal society of edinburgh, vol. xxxvii, part i, pp. - .] [footnote v: american geologist, vol. viii, p. .] [footnote w: forschungen zur deutschen landes und volkskunde von dr. a. kirchhoff. bd. vi, heft i.] when the first edition was issued, two years ago, there seemed to be a general acceptance of all the facts detailed in it which directly connected man with the glacial period both in america and in europe; and, indeed, i had studiously limited myself to such facts as had been so long and so fully before the public that there would seem to be no necessity for going again into the details of evidence relating to them. it appears, however, that this confidence was ill-founded; for the publication of the book seems to have been the signal for a confident challenge, by mr. w. h. holmes, of all the american evidence, with intimations that the european also was very likely equally defective.[x] in particular mr. holmes denies the conclusiveness of the evidence of glacial man adduced by dr. abbott and others at trenton, n. j.; dr. metz, at madisonville, ohio; mr. mills, at newcomerstown, ohio; and miss babbitt, at little falls, minn. [footnote x: journal of geology, vol. i, pp. - , - ; american geologist, vol. xi, pp. - .] the sum of mr. holmes's effort amounts, however, to little more than the statement that, with a limited amount of time and labour, neither he nor his assistants had been able to find any implements in undisturbed gravel in any of these places; and the suggestion of various ways in which he thinks it possible that the observers mentioned may have been deceived as to the original position of the implements found. but, as had been amply and repeatedly published,[y] professor j. d. whitney, professor lucien carr, professor n. s. shaler, professor f. w. putnam, of harvard university, besides dr. c. c. abbott, all expressly and with minute detail describe finding implements in the undisturbed gravel at trenton, which no one denies to be of glacial origin. in the face of such testimony, which had been before the public and freely discussed for several years, it is an arduous undertaking for mr. holmes to claim that none of the implements have been found in place, because he and his assistants (whose opportunities for observation had scarcely been one twentieth part as great as those of the others) failed to find any. to see how carefully the original observations were made, one has but to read the reports to professor putnam which have from time to time appeared in the proceedings of the peabody museum and of the boston society of natural history,, and which are partially summed up in the thirty-second chapter of dr. abbott's volume on primitive industry. [footnote y: proceedings of the boston society of natural history, vol. xxi, january , ; report of the peabody museum, vol. ii, pp. - ; chap, xxxii of abbott's primitive industry; american geologist, vol. xi, pp. - .] in the case of the discovery at newcomerstown, mr. holmes is peculiarly unfortunate in his efforts to present the facts, since, in endeavouring to represent the conditions under which the implement was found by mr. mills, he has relied upon an imaginary drawing of his own, in which an utterly impossible state of things is pictured. the claim of mr. holmes in this case, as in the other, is that possibly the gravel in which the implements were found had been disturbed. in some cases, as in little falls and at madison ville, he thinks the implements may have worked down to a depth of several feet by the overturning of trees or by the decay of the tap-root of trees. a sufficient answer to these suggestions is, that mr. holmes is able to find no instance in which the overturning of trees has disturbed the soil to a depth of more than three or four feet, while some of the implements in these places had been found buried from eight to sixteen feet. even if, as mr. chamberlin suggests,[z] fifty generations of trees have decayed on the spot since the retreat of the ice, it is difficult to see how that would help the matter, since the effect could not be cumulative, and fifty upturnings of three or four feet would not produce the results of one upturning of eight feet. moreover, at trenton, where the upturning of trees and the decaying of tap-roots would have been as likely as anywhere to bury implements, none of those of flint or jasper (which occur upon the surface by tens of thousands) are buried more than a foot in depth; while the argillite implements occur as low down as fifteen or twenty feet. this limitation of flint and jasper implements to the surface is conclusively shown not only by dr. abbott's discoveries, but also by the extensive excavations at trenton of mr. ernest volk, whose collections formed so prominent a part of professor putnam's palæolithic exhibit at the columbian exposition at chicago. in the village sites explored by mr. volk, argillite was the exclusive material of the implements found in the lower strata of gravel. similar results are indicated by the excavations of mr. h. c. mercer at point pleasant, pa., about twenty miles above trenton, where, in the lower strata, the argillite specimens are sixty-one times more numerous than the jasper are. [footnote z: american geologist, vol. xi, p. .] to discredit the discoveries at trenton and newcomerstown, mr. holmes relies largely upon the theory that portions of gravel from the surface had slid down to the bottom of the terrace, carrying implements with them, and forming a talus, which, he thinks, mr. mills, dr. abbott, and the others have mistaken for undisturbed strata of gravel. in his drawings mr. holmes has even represented the gravel at newcomerstown as caving down into a talus without disturbing the strata to any great extent, and at the same time he speaks slightingly of the promise which i had made to publish a photograph of the bank as it really was. in answer, it is sufficient to give, first, the drawing made at the time by mr. mills, to show the general situation of the gravel bank at newcomerstown, in which the implement figured on page was found; and, secondly, an engraving from a photograph of the bank, taken by mr. mills after the discovery of the implement, but before the talus had obscured its face. the implement was found by mr. mills with its point projecting from a fresh exposure of the terrace, just after a mass, loosened by his own efforts, had fallen away. the gravel is of such consistency that every sign of stratification disappears when it falls down, and there could be no occasion for a mistake even by an ordinary observer, while mr. mills was a well-trained geologist and collector, making his notes upon the spot.[aa] [footnote aa: the popular science monthly, vol. xliii, pp. - .] [illustration: height of terrace exposed, feet. palæolith was found - / feet from surface.] [illustration: terrace in newcomerstown, showing where w. c. mills found the palæolithic implement.] i had thought at first that mr. holmes had made out a better case against the late miss babbitt's discoveries at little falls (referred to on page ), but in the american geologist for may, , page , mr. warren upham, after going over the evidence, expresses it as still his conviction that mr. holmes's criticism fails to shake the force of the original evidence, so that i do not see any reason for modifying any of the statements made in the body of the book concerning the implements supposed to have been found in glacial deposits. yet if i had expected such an avalanche of criticism of the evidence as has been loosened, i should at the time have fortified my statements by fuller references, and should possibly have somewhat enlarged the discussion. but this seemed then the less necessary, from the fact that mr. mcgee had, in most emphatic manner, indorsed nearly every item of the evidence adduced by me, and much more, in an article which appeared in the popular science monthly four years before the publication of the volume (november, ). in this article he had said: "but it is in the aqueo-glacial gravels of the delaware river at trenton, which were laid down contemporaneously with the terminal moraine one hundred miles farther northward, and which have been so thoroughly studied by abbott, that the most conclusive proof of the existence of glacial man is found" (p. ). "excluding all doubtful cases, there remains a fairly consistent body of testimony indicating the existence of a widely distributed human population upon the north. american continent during the later ice epoch" (p. ). "however the doubtful cases may be neglected, the testimony is cumulative, parts of it are unimpeachable, and the proof of the existence of glacial man seems conclusive" (p. ). in view of the grossly erroneous statements made by mr. mcgee concerning the nampa image (described on pages , ), it is necessary for me to speak somewhat more fully of this important discovery. the details concerning the evidence were drawn out by me at length in two communications to the boston society of natural history (referred to on page ), which fill more than thirty pages of closely printed matter, while two or three years before the appearance of the volume the facts had been widely published in the new york independent, the scientific american, the nation, scribner's magazine, and the atlantic monthly, and in washington at a meeting of the geological society of america in . in the second communication to the boston society of natural history an account was given of a personal visit to the snake river valley, largely for the purpose of further investigation of the evidence brought to my notice by mr. charles francis adams, and of the conditions under which the figurine was found. among the most important results of this investigation was the discovery of numerous shells under the lava deposits, which mr. dall, of the united states geological survey, identified for me as either post-tertiary or late pliocene; thus throwing the superficial lava deposits of the region into the quaternary period, and removing from the evidence the antecedent improbability which would bear so heavily against it if we were compelled to suppose that the lava of the snake river region was all of tertiary or even of early quaternary age. furthermore, the evidence of the occurrence of a great _débâcle_ in the snake river valley during the glacial period, incident upon the bursting of the banks of lake bonneville, goes far to remove antecedent presumptions against the occurrence of human implements in such conditions as those existing at nampa (see below, pp. - ). mr. mcgee's misunderstanding of the evidence on one point is so gross, that i must make special reference to it. he says[ab] that this image "is alleged to have been pounded out of volcanic tuff by a heavy drill, ... under a thick tertiary lava bed." the statement of facts on page bears no resemblance to this representation. it is there stated that there were but fifteen feet of lava, and that near the surface; that below this there was nothing but alternating beds of clay and quicksand, and that the lava is post-tertiary. the sand-pump i should perhaps have described more fully in the book, as i had already done in the communication to the boston society of natural history. it was a tube eight feet long, with a valve at the bottom three and a half inches in diameter on the inside. through this it was the easiest thing in the world for the object, which is only one inch and a half long, to be brought up in the quicksand without injury. [footnote ab: literary northwest, vol. ii, p. .] the baseless assertions of mr. mcgee, involving the honesty of messrs. kurtz and duffes, are even less fortunate and far more reprehensible. "it is a fact," says mr. mcgee, "that one of the best-known geologists of the world chanced to visit nampa while the boring was in progress, and the figurine and the pretty fiction were laid before him. he recognized the figurine as a toy such as the neighbouring indians give their children, and laughed at the story; whereupon the owner of the object enjoined secrecy, pleading: 'don't give me away; i've fooled a lot of fellows already, and i'd like to fool some more.'"[ac] this well-known geologist, on being challenged by professor claypole[ad] to give "a full, exact, and certified statement of the conversation" above referred to, proved to be major powell, who responded with the following statement: "in the fall of the writer visited boise city, in idaho [twenty miles from nampa]. while stopping at a hotel, some gentlemen called on him to show him a figurine which they said they had found in sinking an artesian well in the neighbourhood, at a depth, if i remember rightly, of more than three hundred feet.... when this story was told the writer, he simply jested with those who claimed to have found it. he had known the indians that live in the neighbourhood, had seen their children play with just such figurines, and had no doubt that the little image had lately belonged to some indian child, and said the same. while stopping at the hotel different persons spoke about it, and it was always passed off as a jest; and various comments were made about it by various people, some of them claiming that it had given them much sport, and that a good many tenderfeet had looked at it, and believed it to be genuine; and they seemed rather pleased that i had detected the hoax."[ae] [footnote ac: american anthropologist, vol. vi, p. : repeated by mr. mcgee in the literary northwest, vol. ii, p. .] [footnote ad: the popular science monthly, vol. xlii, p. .] [footnote ae: ibid., vol. xliii, pp. , .] thus it appears that major powell has made no such statement, at least in public, as mr. mcgee attributes to him. it should be said, also, that major powell's memory is very much at fault when he affirms that there is a close resemblance between this figurine and some of the children's playthings among the pocatello indians. on the contrary, it would have been even more of a surprise to find it in the hands of these children than to find it among the prehistoric deposits on the pacific coast. to most well-informed people it is sufficient to know that no less high authorities than mr. charles francis adams and mr. g. m. gumming, general manager for the union pacific line for that district, carefully investigated the evidence at the time of the discovery, and, knowing the parties, were entirely satisfied with its sufficiency. it was also subjected to careful examination by professor f. w. putnam, who discerned, in a deposit of an oxide of iron on various parts of the image, indubitable evidence that it was a relic which had lain for a long time in some such condition as was assigned to it in the bottom of the well--all of which is detailed in the papers referred to below, on page . finally, the discovery, both in its character and conditions, is in so many respects analogous to those made under table mountain, near sonora, cal. (described on pages - ), that the evidence of one locality adds cumulative force to that of the other. the strata underneath the lava in which these objects were found are all indirectly, but pretty certainly, connected with the glacial period.[af] no student of glacial archæology, therefore, can hereafter afford to disregard these facts from the pacific coast. [footnote af: see below, p. .] oberlin, ohio, _june , _. preface to the first edition. the wide interest manifested in my treatise upon the ice age in north america and its bearing upon the antiquity of man (of which a third edition was issued a year ago), seemed to indicate the desirability of providing for the public a smaller volume discussing the broader question of man's entire relation to the glacial period in europe as well as in america. when the demand for such a volume became evident, i set about preparing for the task by spending, first, a season in special study of the lava-beds of the pacific coast, whose relations to the glacial period and to man's antiquity are of such great interest; and, secondly, a summer in europe, to enable me to compare the facts bearing upon the subject on both continents. of course, the chapters of the present volume relating to america cover much of the same ground gone over in the previous treatise; but the matter has been entirely rewritten and very much condensed, so as to give due proportions to all parts of the subject. it will interest some to know that most of the new material in this volume was first wrought over in my second course of lowell institute lectures, given in boston during the month of march last. i am under great obligations to mr. charles francis adams for his aid in prosecuting investigations upon the pacific coast of america; and also to dr. h. w. crosskey, of birmingham, england, and to mr. g. w. lamplugh, of bridlington, as well as to mr. c. e. de rance and mr. clement reid, of the british geological survey, besides many others in england who have facilitated my investigations; but pre-eminently to prof. percy f. kendall, of stockport, who consented to prepare for me the portion of chapter vi which relates to the glacial phenomena of the british isles. i have no doubt of the general correctness of the views maintained by him, and little doubt, also, that his clear and forcible presentation of the facts will bring about what is scarcely less than a revolution in the views generally prevalent relating to the subject of which he treats. for the glacial facts relating to france and switzerland i am indebted largely to m. falsan's valuable compendium, la période glaciaire. it goes without saying, also, that i am under the deepest obligation to the works of prof. james geikie upon the great ice age and upon prehistoric europe, and to the remarkable volume of the late mr. james croll upon climate and time, as well as to the recent comprehensive geological treatises of sir archibald geikie and prof. prestwich. finally, i would express my gratitude for the great courtesy of prof. fraipont, of liége, in assisting me to an appreciation of the facts relating to the late remarkable discovery of two entire skeletons of paleolithic man in the grotto of spy. comparative completeness is also given to the volume by the appendix on the question of man's existence during the tertiary period, prepared by the competent hand of prof. henry w. haynes, of boston. i trust this brief treatise will be useful not only in _interesting_ the general public, but in giving a clear view of the present state of progress in one department of the inquiries concerning man's antiquity. if the conclusions reached are not as positive as could be wished, still it is both desirable and important to see what degree of indefiniteness rests upon the subject, in order that rash speculations may be avoided and future investigations directed in profitable lines. g. frederick wright. oberlin, ohio, _may , _. contents. pages chapter i. introductory - chapter ii. existing glaciers - in europe; in asia; in oceanica; in south america; on the antarctic continent; in north america. chapter iii. glacial motion - chapter iv. signs of past glaciation - chapter v. ancient glaciers in the western hemisphere - new england; new york, new jersey, and pennsylvania; the mississippi basin; west of the rocky mountains. chapter vi. ancient glaciers in the eastern hemisphere - central and southern europe; the british isles--the preglacial level of the land, the great glacial centres, the confluent glaciers, the east anglian glacier, the so-called great submergence; northern europe; asia; africa. chapter vii. drainage systems in the glacial period - in america--preglacial erosion, buried outlets and channels, ice-dams, ancient river terraces; in europe. chapter viii. relics of man in the glacial period - in glacial terraces of the united states; in glacial terraces of europe; in cave deposits in the british isles; in cave deposits on the continent; extinct animals associated with man; earliest man on the pacific coast of north america. chapter ix. the cause of the glacial period - chapter x. the date of the glacial period - appendix on the tertiary man - index - list of illustrations. fig. page . zermatt glacier . formation of veined structure , . formation of marginal fissures and veins . fissures and seracs . section across glacial valley, showing old lateral moraines . mont blanc glacier region . svartisen glacier . floating berg . iceberg in the antarctic ocean . map of southeastern alaska . map of glacier bay, alaska . front of muir glacier . map of glaciers in the st. elias alps . map of greenland . diagram showing the character of glacial motion . line of most rapid glacial motion . diagram showing retardation of the bottom of a glacier . bed-rock scored with glacial marks . scratched stone from the till of boston . typical section of till in seattle, wash. . ideal section showing how the till overlies the stratified rocks . vessel rock, a glacial boulder . map of rhône glacier . conglomerate boulder found in boone county, ky. . mohegan rock . drumlins in goffstown, n. h. . map of drumlins in the vicinity of boston . section of kame . map of kames in andover, mass. . longitudinal kames near hingham, mass. . map showing the kames of maine and southeastern new hampshire . western face of the kettle moraine near eagle, wis. . section of the east-and-west glacial furrows on kelly's island . same as the preceding . section of till near germantown, ohio . moraines of grape creek, col. . map of north america in the ice period . quartzite boulder on mont lachat . map showing glaciated areas in north america and europe . maps showing lines of _débris_ extending from the alps into the plains of the po . section of the cefn cave . map showing moraine between speeton and flamborough . diagram-section near cromer . section through the westerly chalk bluff at trimingham, norfolk . section across wales . section of cliff at flamborough head . enlarged section of the shelly sand and surrounding clay at _b_ in preceding figure . map showing the glaciated area of europe . map showing old channel and mouth of the hudson . new york harbor in preglacial times . section across the valley of the cuyahoga river . map of mississippi river from fort snelling to minneapolis . map showing the effect of the glacial dam at cincinnati . map of lake erie-ontario . map of cuyahoga lake . section of the lake ridges near sandusky, ohio . map showing stages of recession of the ice in minnesota . glacial terrace on raccoon creek, in ohio . ideal section across a river-bed in drift region . map of lakes bonneville and lahontan . parallel roads of glen roy . map showing glacial terraces on the delaware and schuylkill rivers . palæolith found by abbott in new jersey . section across the delaware river at trenton, n. j. . section of the trenton gravel . face view of argillite implement found by dr. c. c. abbott in . . argillite implement found by dr. c. c. abbott, march, . chipped pebble of black chert found by dr. c. l. metz, october, . map showing glaciated area in ohio . palæoliths from newcomerstown and amiens (face view) . edge view of the preceding . section across the mississippi valley at little falls, minn. . quartz implement found by miss f. e. babbitt, , at little falls, minn . argillite implement found by h. t. cresson, . general view of baltimore and ohio railroad cut, claymont, del. . section across valley of the somme . mouth of kent's hole . engis skull (reduced) . comparison of forms of skulls . skull of the man of spy . tooth of machairodus neogæus . perfect tooth of an elephas . skull of hyena spelæa . celebrated skeleton of mammoth in st. petersburg museum . molar tooth of mammoth . tooth of mastodon americanus . skeleton of mastodon americanus . skeleton of rhinoceros tichorhinus . skull of cave-bear . skeleton of the irish elk . musk-sheep . reindeer . section across table mountain, tuolumne county, cal. . calaveras skull . three views of nampa image, drawn to scale . map showing pocatello, nampa, and the valley of snake river . section across the channel of the stanislaus river . diagram showing effect of precession . map showing course of currents in the atlantic ocean . map showing how the land clusters about the north pole . diagram showing oscillations of land-surface and ice-surface during the glacial epoch . diagram of eccentricity and precession . map of the niagara river below the falls . section of strata along the niagara gorge . map showing the recession of the horseshoe falls since . section of kettle-hole near pomp's pond, andover, mass. . flint-flakes collected by abbé bourgeois maps. to face page contour and glacial map of the british isles _frontispiece._ map showing the glacial geology of the united states map of glacial movements in france and switzerland man and the glacial period. chapter i. introductory. that glaciers now exist in the alps, in the scandinavian range, in iceland, in the himalayas, in new zealand, in patagonia, and in the mountains of washington, british columbia, and southeastern alaska, and that a vast ice-sheet envelops greenland and the antarctic continent, are statements which can be verified by any one who will take the trouble to visit those regions. that, at a comparatively recent date, these glaciers extended far beyond their present limits, and that others existed upon the highlands of scotland and british america, and at one time covered a large part of the british isles, the whole of british america, and a considerable area in the northern part of the united states, are inferences drawn from phenomena which are open to every one's observations. that man was in existence and occupied both europe and america during this great expansion of the northern glaciers is proved by evidence which is now beyond dispute. it is the object of the present volume to make a concise presentation of the facts which have been rapidly accumulating during the past few years relating to the glacial period and to its connection with human history. before speaking of the number and present extent of existing glaciers, it will be profitable, however, to devote a little attention to the definition of terms. [illustration: fig. .--zermatt glacier (agassiz).] a _glacier_ is a mass of ice so situated and of such size as to have motion in itself. the conditions determining the character and rate of this motion will come up for statement and discussion later. it is sufficient here to say that ice has a capacity of movement similar to that possessed by such plastic substances as cold molasses, wax, tar, or cooling lava. the limit of a glacier's _motion_ is determined by the forces which fix the point at which its final melting takes place. this will therefore depend upon both the warmth of the weather and upon the amount of ice. if the ice is abundant, it will move farther into the region of warm temperature than it will if it is limited in supply. upon ascending a glacier far enough, one reaches a comparatively motionless part corresponding to the lake out of which a river often flows. technically this is called the _névé_. _glacial ice_ is formed from snow where the annual fall is in excess of the melting power of the sun at that point. through the influence of pressure, such as a boy applies to a snow-ball (but which in the _névé_-field arises from the weight of the accumulating mass), the lower strata of the _névé_ are gradually transformed into ice. this process, is also assisted by the moisture which percolates through the snowy mass, and which is furnished both by the melting of the surface snow and by occasional rains. the division between the _névé_ and the glacier proper is not always easily determined. the beginnings of the glacial movement--that is, of the movement of the ice-stream flowing out of the _névé_-field--are somewhat like the beginnings of the movement of the water from a great lake into its outlet. the _névé_ is the reservoir from which the glacier gets both its supply of ice and the impulse which gives it its first movement. there can not be a glacier without a _névé_-field, as there can not be a river without a drainage basin. but there may be a _névé_-field without a glacier--that is, a basin may be partially filled with snow which never melts completely away, while the equilibrium of forces is such that the ice barely reaches to the outlet from which the tongue-like projection (to which the name glacier would be applied) fails to emerge only because of the lack of material. [illustration: fig. .--illustrates the formation of veined structure by pressure at the junction of two branches.] a glacier is characterised by both _veins_ and _fissures_. the veins give it a banded or stratified appearance, blue alternating with lighter-coloured portions of ice. as these bands are not arranged with any apparent uniformity in the glacier, their explanation has given rise to much discussion. sometimes the veins are horizontal, sometimes vertical, and at other times at an angle with the line of motion. on close investigation, however, it is found that the veins are always at right angles to the line of greatest pressure. this leads to the conclusion that pressure is the cause of the banded structure. the blue strata in the ice are those from which the particles of air have been expelled by pressure; the lighter portions are those in which the particles are less thoroughly compacted. snow is but pulverized ice, and differs in colour from the compact mass for the same reason that almost all rocks and minerals change their colour when ground into a powder. [illustration: figs. , .--illustrate the formation of marginal fissures and veins.] [illustration: fig. .--_c_, _c_, show fissures and seracs where the glacier moves down the steeper portion of its incline; _s_, _s_, show the vertical structure produced by pressure on the gentler slopes.] the _fissures_, which, when of large size, are called _crevasses_, are formed in those portions of a glacier where, from some cause, the ice is subjected to slight tension. this occurs especially where, through irregularities in the bottom, the slope of the descent is increased. the ice, then, instead of moving in a continuous stream at the top, cracks open along the line of tension, and wedge-shaped fissures are formed extending from the top down to a greater or less distance, according to the degree of tension. usually, however, the ice remains continuous in the lower strata, and when the slope is diminished the pressure reunites the faces of the fissure, and the surface becomes again comparatively smooth. where there are extensive areas of tension, the surface of the ice sometimes becomes exceedingly broken, presenting a tangled mass of towers, domes, and pinnacles of ice called _seracs_. [illustration: fig. .--section across glacial valley, showing old lateral moraines.] like running water, moving ice is a powerful agent in _transporting_ rocks and earthy _débris_ of all grades of fineness; but, owing to the different consistencies of ice and water, there are great differences in the mode and result of transportation by them. while water can hold in suspension only the very finest material, ice can bear upon its surface rocks of the greatest magnitude, and can roll or shove along under it boulders and pebbles which would be unaffected except by torrential currents of water. we find, therefore, a great amount of earthy material of all sizes upon the top of a glacier, which has reached it very much as _débris_ reaches the bed of a river, namely, by falling down upon it from overhanging cliffs, or by land-slides of greater or less extent. such material coming into a river would either disappear beneath its surface, or would form a line of _débris_ along the banks; in both cases awaiting the gradual erosion and transportation which running water is able to effect. but, in case of a glacier, the material rests upon the surface of the ice, and at once begins to partake of its motion, while successive accessions of material keep up the supply at any one point, so as to form a train of boulders and other _débris_, extending below the point as far as the glacial motion continues. such a line of _débris_ is called a _moraine_. when it forms along the edge of the ice, it is called a _lateral_ moraine. it is easy to see that, where glaciers come out from two valleys which are tributary to a larger valley, their inner sides must coalesce below the separating promontory, and the two lateral moraines will become united and will move onward in the middle of the surface of the glacier. such lines of _débris_ are called _medial_ moraines. these are characteristic of all extensive glaciers formed by the union of tributaries. there is no limit to the number of medial moraines, except in the number of tributaries. a medial moraine, when of sufficient thickness, protects the ice underneath it from melting; so that the moraine will often appear to be much larger than it really is: what seems to be a ridge of earthy material being in reality a long ridge of ice, thinly covered with earthy _débris_, sliding down the slanting sides as the ice slowly wastes away large blocks of stone in the same manner protect the ice from melting underneath, and are found standing on pedestals of ice, often several feet in height. an interesting feature of these blocks is that, when the pedestal fails, the block uniformly falls towards the sun, since that is the side on which the melting has proceeded most rapidly. if the meteorological forces are so balanced that the foot of a glacier remains at the same place for any great length of time, there must be a great accumulation of earthy _débris_ at the stationary point, since the motion of the ice is constantly bearing its lines of lateral and medial moraine downwards to be deposited, year by year, at the melting line along the front. such accumulations are called _terminal_ moraines, and the process of their formation may be seen at the foot of almost any large glacier. the pile of material thus confusedly heaped up in front of some of the larger glaciers of the world is enormous. the melting away of the lower part of a glacier gives rise also to several other characteristic phenomena. where the foot of a glacier chances to be on comparatively level land, the terminal moraine often covers a great extent of ice, and protects it from melting for an indefinite period of time. when the ice finally melts away and removes the support from the overlying morainic _débris_, this settles down in a very irregular manner, leaving enclosed depressions to which there is no natural outlet. these depressions, from their resemblance to a familiar domestic utensil, are technically known as _kettle-holes_. the terminal moraines of ancient glaciers may often be traced by the relative abundance of these kettle-holes. the streams of water arising both from the rainfall and from the melting of the ice also produce a peculiar effect about the foot of an extensive glacier. sometimes these streams cut long, open channels near the end of the glacier, and sweep into it vast quantities of morainic material, which is pushed along by the torrential current, and, after being abraded, rolled, and sorted, is deposited in a delta about its mouth, or left stranded in long lines between the ice-walls which have determined its course. at other times the stream has disappeared far back in the glacier, and plunged into a crevasse (technically called a _moulin_), whence it flows onwards as a subglacial stream. but in this case the deposits might closely resemble those of the previous description. in both cases, when the ice has finally melted away, peculiar ridge-like deposits of sorted material remain, to mark the temporary line of drainage. these exist abundantly in most regions which have been covered with glacial ice, and are referred to in scotland as _kames_, in ireland as _eskers_, and in sweden as _osars_. in this volume we shall call them _kames_, and the deltas spread out in front of them will be referred to as _kame-plains_. with this preliminary description of glacial phenomena, we will proceed to give, first, a brief enumeration and description of the ice-fields which are still existing in the world; second, the evidences of the former existence of far more extensive ice-fields; and, third, the relation of the glacial period to some of the vicissitudes which have attended the life of man in the world. the geological period of which we shall treat is variously designated by different writers. by some it is simply called the "post-tertiary," or "quaternary"; by others the term "post-pliocene" is used, to indicate more sharply its distinction from the latter portion of the tertiary period; by others this nicety of distinction is expressed by the term "pleistocene." but, since the whole epoch was peculiarly characterised by the presence of glaciers, which have not even yet wholly disappeared, we may properly refer to it altogether under the descriptive name of "glacial" period. chapter ii. existing glaciers. _in europe._--our specific account of existing glaciers naturally begins with those of the alps, where hugi, charpentier, agassiz, forbes, and guyot, before the middle of this century, first brought clearly to light the reality and nature of glacial motion. according to professor heim, of zürich, the total area covered by the glaciers and ice-fields of the alps is upwards of three thousand square kilometres (about eleven hundred square miles). the swiss alps alone contain nearly two-thirds of this area. professor heim enumerates , distinct glaciers in the region. of these, are in france, in italy, in switzerland, and in austria. desor describes fourteen principal glacial districts in the alps, the westernmost of which is that of mont pelvoux, in dauphiny, and the easternmost that in the vicinity of the gross glockner, in carinthia. the most important of the alpine systems are those which are grouped around mont blanc, monte rosa, and the finsteraarhorn, the two former peaks being upwards of fifteen thousand feet in height, and the latter upwards of fourteen thousand. the area covered by glaciers and snow-fields in the bernese oberland, of which finsteraarhorn is the culminating point, is about three hundred and fifty square kilometres (a hundred square miles), and contains the aletsch glacier, which is the longest in europe, extending twenty-one kilometres (about fourteen miles) from the _névé_-field to its foot. the mer de glace, which descends from mont blanc to the valley of chamounix, has a length of about eight miles below the _névé_-field. in all, there are estimated to be twenty-four glaciers in the alps which are upwards of four miles long, and six which are upwards of eight miles in length. the principal of these are the mer de glace, of chamounix, on mont blanc; the gorner glacier, near zermatt, on monte rosa; the lower glacier of the aar, in the bernese oberland; and the aletsch glacier and glacier of the rhône, in vallais; and the pasterzen, in carinthia. [illustration: fig. .--mount blanc glacier region: _m_, mer de glace; _g_, du géant; _l_, leschaux; _t_, taléfre; _b_, bionassay; _b_, bosson.] these glaciers adjust themselves to the width of the valleys down which they flow, in some places being a mile or more in width, and at others contracting into much narrower compass. the greatest depth which agassiz was able directly to measure in the aar glacier was two hundred and sixty metres (five hundred and twenty-eight feet), but at another point the depth was estimated by him to be four hundred and sixty metres (or fifteen hundred and eighty-four feet). the glaciers of the alps are mostly confined to the northern side and to the higher portions of the mountain-chain, none of them descending below the level of four thousand feet, and all of them varying slightly in extent, from year to year, according as there are changes in the temperature and in the amount of snow-fall. the pyrenees, also, still maintain a glacial system, but it is of insignificant importance. this is partly because the altitude is much less than that of the alps, the culminating point being scarcely more than eleven thousand feet in height. doubtless, also, it is partly due to the narrowness of the range, which does not provide gathering-places for the snow sufficiently extensive to produce large glaciers. the snow-fall also is less upon the pyrenees than upon the alps. as a consequence of all these conditions, the glaciers of the pyrenees are scarcely more than stationary _névé_-fields lingering upon the north side of the range. the largest of these is near bagnères de luchon, and sends down a short, river-like glacier. in scandinavia the height of the mountains is also much less than that of the alps, but the moister climate and the more northern latitude favours the growth of glaciers at a much lower level north of the sixty-second degree of latitude, the plateaus over five thousand feet above the sea pretty generally are gathering-places for glaciers. from the justedal a snow-field, covering five hundred and eighty square miles, in latitude °, twenty-four glaciers push outwards towards the german sea, the largest of which is five miles long and three-quarters of a mile wide. the fondalen snow-field, between latitudes ° and °, covers an area about equal to that of the justedal; but, on account of its more northern position, its glaciers descend through the valleys quite to the ocean-level. the folgofon snow-field is still farther south, but, though occupying an area of only one hundred square miles, it sends down as many as three glaciers to the sea-level. the total area of the scandinavian snow-fields is about five thousand square miles. in sweden dr. svenonius estimates that there are, between latitudes ° and - / °, twenty distinct groups of glaciers, covering an area of four hundred square kilometres (one hundred and forty-four square miles), and he numbers upwards of one hundred distinct glaciers of small size. as is to be expected, the large islands in the polar sea north of europe and asia are, to a great extent, covered with _névé_-fields, and numerous glaciers push out from them to the sea in all directions, discharging their surplus ice as bergs, which float away and cumber the waters with their presence in many distant places. [illustration: fig. .--the svartisen glacier on the west coast of norway, just within the arctic circle, at the head of a fiord ten miles from the ocean. the foot of the glacier is one mile wide, and a quarter of a mile back from the water. terminal moraine in front. (photographed by dr. l. c. warner.)] the island of spitzbergen, in latitude ° to °, is favourably situated for the production of glaciers, by reason both of its high northern latitude, and of its relation to the gulf stream, which conveys around to it an excessive amount of moisture, thus ensuring an exceptionally large snow-fall over the island. the mountainous character of the island also favours the concentration of the ice-movement into glaciers of vast size and power. still, even here, much of the land is free from snow and ice in summer. but upon the northern portion of the island there is an extensive table-land, upwards of two thousand feet above the sea, over which the ice-field is continuous. four great glaciers here descend to tide-water in magdalena bay. the largest of these presents at the front a wall of ice seven thousand feet across and three hundred feet high; but, as the depth of the water is not great, few icebergs of large size break off and float away from it. nova zembla, though not in quite so high latitude, has a lower mean temperature upon the coasts than spitzbergen. owing to the absence of high lands and mountains, however, it is not covered with perpetual snow, much less with glacial ice, but its level portions are "carpeted with grasses and flowers," and sustain extensive forests of stunted trees. franz-josef land, to the north of nova zembla, both contains high mountains and supports glaciers of great size. mr. payer conducted a sledge party into this land in , and reported that a precipitous wall of glacial ice, "of more than a hundred feet in height, formed the usual edge of the coast." but the motion of the ice is very slow, and the ice coarse-grained in structure, and it bears a small amount only of morainic material. so low is here the line of perpetual snow, that the smaller islands "are covered with caps of ice, so that a cross-section would exhibit a regular flat segment of ice." it is interesting to note, also, that "many ice-streams, descending from the high _névé_ plateau, spread themselves out over the mountain-slopes," and are not, as in the alps, confined to definite valleys. iceland seems to have been properly named, since a single one of the snow-fields--that of vatnajoküll, with an extreme elevation of only six thousand feet--is estimated by helland to cover one hundred and fifty norwegian square miles (about seven thousand english square miles), while five other ice-fields (the langjoküll, the hofsjoküll, the myrdalsjoküll, the drangajoküll, and the glamujoküll) have a combined area of ninety-two norwegian or about four thousand five hundred english square miles. the glaciers are supposed by whitney to have been rapidly advancing for some time past. _in asia._--notwithstanding its lofty mountains and its great extent of territory lying in high latitudes, glaciers are for two reasons relatively infrequent: . the land in the more northern latitudes is low. . the dryness of the atmosphere in the interior of the continent is such that it unduly limits the snow-fall. long before they reach the central plateau of asia, the currents of air which sweep over the continent from the indian ocean have parted with their burdens of moisture, having left them in a snowy mantle upon the southern flanks of the himalayas. as a result, we have the extensive deserts of the interior, where, on account of the clear atmosphere, there is not snow enough to resist continuously the intense activity of the unobstructed rays of the sun. in spite of their high latitude and considerable elevation above the sea-level, glaciers are absent from the ural mountains, for the range is too narrow to afford _névé_-fields of sufficient size to produce glaciers of large extent. the caucasus mountains present more favourable conditions, and for a distance of one hundred and twenty miles near their central portion have an average height of , feet, with individual peaks rising to a height of , feet or more; but, owing to their low latitude, the line of perpetual snow scarcely reaches down to the , -foot level. so great are the snow-fields, however, above this height that many glaciers push their way down through the narrow mountain-gorges as far as the , -foot level. the himalaya mountains present many favourable conditions for the development of glaciers of large size. the range is of great extent and height, thus affording ample gathering-places for the snows, while the relation of the mountains to the moisture-laden winds from the indian ocean is such that they enjoy the first harvest of the clouds where the interior of asia gets only the gleanings. as is to be expected, therefore, all the great rivers which course through the plains of hindustan have their rise in large glaciers far up towards the summits of the northern mountains. the indus and the ganges are both glacial streams in their origin, as are their larger tributary branches--the basha, the shigar, and the sutlej. many of the glaciers in the higher levels of the himalaya mountains where these streams rise have a length of from twenty-five to forty miles, and some of them are as much as a mile and a half in width and extend for a long distance, with an inclination as small as one degree and a half or one hundred and thirty-eight feet to a mile. in the mustagh range of the western himalayas there are two adjoining glaciers whose united length is sixty-five miles, and another not far away which is twenty-one miles long and from one to two miles wide in its upper portion. its lower portion terminates at an altitude of , feet above tide, where it is three miles wide and two hundred and fifty feet thick. _oceanica._---passing eastward to the islands of the pacific ocean, new zealand is the only one capable of supporting glaciers. their existence on this island seems the more remarkable because of its low latitude ( ° to °); but a grand range of mountains rises abruptly from the water on the western coast of the southern island, culminating in mount cook, , feet above the sea, and extending for a distance of about one hundred miles. the extent and height of this chain, coupled with the moisture of the winds, which sweep without obstruction over so many leagues of the tropical pacific, are specially favourable to the production of ice-fields of great extent. consequently we find glaciers in abundance, some of which are not inferior in extent to the larger ones of the alps. the tasman glacier, described by haas, is ten miles long and nearly two miles broad at its termination, "the lower portion for a distance of three miles being covered with morainic _detritus_." the mueller glacier is about seven miles long and one mile broad in its lower portion. _south america._--in america, existing glaciers are chiefly confined to three principal centres, namely, to the andes, south of the equator; to the cordilleras, north of central california; and to greenland. in south america, however, the high mountains of ecuador sustain a few glaciers above the twelve-thousand-foot level. the largest of these are upon the eastern slope of the mountains, giving rise to some of the branches of the amazon--indeed, on the flanks of cotopaxi, chimborazo, and illinissa there are some glaciers in close proximity to the equator which are fairly comparable in size to those of the alps. in chili, at about latitude °, glaciers begin to appear at lower levels, descending beyond the six-thousand-foot line, while south of this both the increasing moisture of the winds and the decreasing average temperature favour the increase of ice-fields and glaciers. consequently, as darwin long ago observed, the line of perpetual snow here descends to an increasingly lower level, and glaciers extend down farther and farther towards the sea, until, in tierra del fuego, at about latitude °, they begin to discharge their frozen contents directly into the tidal inlets. darwin's party surveyed a glacier entering the gulf of penas in latitude ° ', which was fifteen miles long, and, in one part, seven broad. at eyre's sound, also, in about latitude °, they found immense glaciers coming clown to the sea and discharging icebergs of great size, one of which, as they encountered it floating outwards, was estimated to be "_at least_ one hundred and sixty-eight feet in total height." in tierra del fuego, where the mountains are only from three thousand to four thousand feet in height and in latitude less than °, darwin reports that "every valley is filled with streams of ice descending to the sea-coast," and that the inlets penetrated by his party presented miniature likenesses of the polar sea. [illustration: fig. .--floating berg, showing the proportions above and under the water. about seven feet under water to one above.] _antarctic continent._--of the so-called antarctic continent little is known; but icebergs of great size are frequently encountered up to ° south latitude, in the direction of cape horn, and as far as latitude ° in the direction of cape of good hope. nearly all that is known about this continent was discovered by sir j. c. ross during the period extending from to , when, between the parallels of ° and ° south latitude, he encountered in his explorations a precipitous mountain coast, rising from seven thousand to ten thousand feet above tide. through the valleys intervening between the mountain-ranges huge glaciers descended, and "projected in many places several miles into the sea and terminated in lofty, perpendicular cliffs. in a few places the rocks broke through their icy covering, by which alone we could be assured that land formed the nucleus of this, to appearance, enormous iceberg."[ag] [footnote ag: quoted by whitney in climatic changes, p. .] again, speaking of the region in the vicinity of the lofty volcanoes terror and erebus, between ten thousand and twelve thousand feet high, the same navigator says: "we perceived a low, white line extending from its extreme eastern point, as far as the eye could discern, to the eastward. it presented an extraordinary appearance, gradually increasing in height as we got nearer to it, and proving at length to be a perpendicular cliff of ice, between one hundred and fifty and two hundred feet above the level of the sea, perfectly flat and level at the top, and without any fissures or promontories on its even, seaward face. what was beyond it we could not imagine; for, being much higher than our mast-head, we could not see anything except the summit of a lofty range of mountains extending to the southward as far as the seventy-ninth degree of latitude. these mountains, being the southernmost land hitherto discovered, i felt great satisfaction in naming after sir edward parry.... whether parry mountains again take an easterly trending and form the base to which this extraordinary mass of ice is attached, must be left for future navigators to determine. if there be land to the southward it must be very remote, or of much less elevation than any other part of the coast we have seen, or it would have appeared above the barrier." this ice-cliff or barrier was followed by captain ross as far as ° west longitude, and found to preserve very much the same character during the whole of that distance. on the lithographic view of this great ice-sheet given in ross's work it is described as "part of the south polar barrier, one hundred and eighty feet above the sea-level, one thousand feet thick, and four hundred and fifty miles in length." a similar vertical wall of ice was seen by d'urville, off the coast of adelie land. he thus describes it: "its appearance was astonishing. we perceived a cliff having a uniform elevation of from one hundred to one hundred and fifty feet, forming a long line extending off to the west.... thus for more than twelve hours we had followed this wall of ice, and found its sides everywhere perfectly vertical and its summit horizontal. not the smallest irregularity, not the most inconsiderable elevation, broke its uniformity for the twenty leagues of distance which we followed it during the day, although we passed it occasionally at a distance of only two or three miles, so that we could make out with ease its smallest irregularities. some large pieces of ice were lying along the side of this frozen coast; but, on the whole, there was open sea in the offing." [ah] [footnote ah: whitney's climatic changes, pp. , .] [illustration: fig. .--iceberg in the antarctic ocean.] _north america._--in north america living glaciers begin to appear in the sierra nevada mountains, in the vicinity of the yosemite park, in central california. here the conditions necessary for the production of glaciers are favourable, namely, a high altitude, snow-fields of considerable extent, and unobstructed exposure to the moisture-laden currents of air from the pacific ocean. sixteen glaciers of small size have been noted among the summits to the east of the yosemite; but none of them descend much below the eleven-thousand-foot line, and none of them are over a mile in length. indeed, they are so small, and their motion is so slight, that it is a question whether or not they are to be classed with true glaciers. owing to the comparatively low elevation of the sierra nevada north of tuolumne county, california, no other living glaciers are found until reaching mount shasta, in the extreme northern part of the state. this is a volcanic peak, rising fourteen thousand five hundred feet above the sea, and having no peaks within forty miles of it as high as ten thousand feet; yet so abundant is the snow-fall that as many as five glaciers are found upon its northern side, some of them being as much as three miles long and extending as low down as the eight-thousand-foot level. upon the southern side glaciers are so completely absent that professor whitney ascended the mountain and remained in perfect ignorance of its glacial system. in mr. clarence king first discovered and described them on the northern side. north of california glaciers characterise the cascade range in increasing numbers all the way to the alaskan peninsula. they are to be found upon diamond peak, the three sisters, mount jefferson, and mount hood, in oregon, and appear in still larger proportions upon the flanks of mount rainier (or tacoma) and mount baker, in the state of washington. the glacier at the head of the white river valley is upon the north side of rainier, and is the largest one upon that mountain, reaching down to within five thousand feet of the sea-level, and being ten miles or more in length. all the streams which descend the valleys upon this mountain are charged with the milky-coloured water which betrays their glacial origin. [illustration: fig. .--map of southeastern alaska. the arrow-points mark glaciers.] in british columbia, glacier station, upon the canadian pacific railroad, in the selkirk mountains, is within half a mile of the handsome illicilliwaet glacier, while others of larger size are found at no great distance. the interior farther north is unexplored to so great an extent that little can be definitely said concerning its glacial phenomena. the coast of british columbia is penetrated by numerous fiords, each of which receives the drainage of a decaying glacier; but none are in sight of the tourist-steamers which thread their way through the intricate network of channels characterising this coast, until the alaskan boundary is crossed and the mouth of the stickeen river is passed. a few miles up from the mouth of the stickeen, however, glaciers of large size come down to the vicinity of the river, both from the north and from the south, and the attention of tourists is always attracted by the abundant glacial sediment borne into the tide-water by the river itself and discolouring the surface for a long distance beyond the outlet. northward from this point the tourist is rarely out of sight of ice-fields. the auk and patterson glaciers are the first to come into view, but they do not descend to the water-level. on nearing holcomb bay, however, small icebergs begin to appear, heralding the first of the glaciers which descend beyond the water's edge. taku inlet, a little farther north, presents glaciers of great size coming down to the sea-level, while the whole length of lynn canal, from juneau to chilkat, a distance of eighty miles, is dotted on both sides by conspicuous glaciers and ice-fields. the davidson glacier, near the head of the canal, is one of the most interesting for purposes of study. it comes down from an unknown distance in the western interior, bearing two marked medial moraines upon its surface. on nearing tide-level, the valley through which it flows is about three-quarters of a mile in width; but, after emerging from the confinement of the valley, the ice spreads out over a fan-shaped area until the width of its front is nearly three miles. the supply of ice not being sufficient to push the front of the glacier into deep water, equilibrium between the forces of heat and cold is established near the water's edge. here, as from year to year the ice melts and deposits its burdens of earthy _débris_, it has piled up a terminal moraine which rises from two hundred to three hundred feet in height, and is now covered with evergreen trees of considerable size. from chilkat, at the head of lynn canal, to the sources of the yukon river, the distance is only thirty-five miles, but the intervening mountain-chain is several thousand feet in height and bears numerous glaciers upon its seaward side. about forty miles west of lynn canal, and separated from it by a range of mountains of moderate height, is glacier bay, at the head of one of whose inlets is the muir glacier, which forms the chief attraction for the great number of tourists that now visit the coast of southeastern alaska during the summer season. this glacier meets tide-water in latitude ° ', and longitude ° ' west of greenwich. it received its name from mr. john muir, who, in company with rev. mr. young, made a tour of the bay and discovered the glacier in . it was soon found that the bay could be safely navigated by vessels of large size, and from that time on tourists in increasing number have been attracted to the region. commodious steamers now regularly run close up to the ice-front, and lie-to for several hours, so that the passengers may witness the "calving" of icebergs, and may climb upon the sides of the icy stream and look into its deep crevasses and out upon its corrugated and broken surface. [illustration: fig. .--map of glacier bay. alaska, and its surroundings. arrow-points indicate glaciated area.] the first persons who found it in their way to pay more than a tourist's visit to this interesting object were rev. j. l. patton, mr. prentiss baldwin, and myself, who spent the entire month of august, , encamped at the foot of the glacier, conducting such observations upon it as weather and equipment permitted. from that time till the summer of no one else stopped off from the tourist steamers to bestow any special study upon it. but during this latter season mr. muir returned to the scene of his discovered wonder, and spent some weeks in exploring the interior of the great ice-field. during the same season, also, professors h. f. reid and h. cushing, with a well-equipped party of young men, spent two months or more in the same field, conducting observations and experiments, of various kinds, relating to the extent, the motion, and the general behaviour of the vast mass of moving ice. [illustration: fig. .--shows central part of the front of muir glacier one half mile distant. near the lower left hand corner the ice is seen one mile distant resting for about one half mile on gravel which it had overrun. the ice is now retreating in the channel. (from photograph.)] the main body of the muir glacier occupies a vast amphitheatre, with diameters ranging from thirty to forty miles, and covers an area of about one thousand square miles. from one of the low mountains near its mouth i could count twenty-six tributary glaciers which came together and became confluent in the main stream of ice. nine medial moraines marked the continued course of as many main branches, which becoming united formed the grand trunk of the glacier. numerous rocky eminences also projected above the surface of the ice, like islands in the sea, corresponding to what are called "_nunataks_" in greenland. the force of the ice against the upper side of these rocky prominences is such as to push it in great masses above the surrounding level, after the analogy of waves which dash themselves into foam against similar obstructions. in front of the _nunataks_ there is uniformly a depression, like the eddies which appear in the current below obstacles in running water. over some portions of the surface of the glacier there is a miniature river system, consisting of a main stream, with numerous tributaries, but all flowing in channels of deep blue ice. before reaching the front of the glacier, however, each one of these plunges down into a crevasse, or _moulin_, to swell the larger current, which may be heard rushing along in an impetuous course hundreds of feet beneath, and far out of sight. the portion of the glacier in which there is the most rapid motion is characterised by innumerable crags and domes and pinnacles of ice, projecting above the general level, whose bases are separated by fissures, extending in many cases more than a hundred feet below the general level. these irregularities result from the combined effect of the differential motion (as illustrated in the diagram on page ), and the influence of sunshine and warm air in irregularly melting the unprotected masses. the description given in our introductory chapter of medial moraines and ice-pillars is amply illustrated everywhere upon the surface of the muir glacier. i measured one block of stone which was twenty feet square and about the same height, standing on a pedestal of ice three or four feet high. the mountains forming the periphery of this amphitheatre rise to a height of several thousand feet; mount fairweather, upon the northwest, from whose flanks probably a portion of the ice comes, being, in fact, more than fifteen thousand feet high. the mouth of the amphitheatre is three miles wide, in a line extending from shoulder to shoulder of the low mountains which guard it. the actual water-front where the ice meets tide-water is one mile and a half.[ai] here the depth of the inlet is so great that the front of the ice breaks off in icebergs of large size, which float away to be dissolved at their leisure. at the water's edge the ice presents a perpendicular front of from two hundred and fifty to four hundred feet in height, and the depth of the water in the middle of the inlet immediately in front of the ice is upwards of seven hundred feet; thus giving a total height to the precipitous front of a thousand feet. [footnote ai: these are the measurements of professor reid. in my former volume i have given the dimensions as somewhat smaller.] the formation of icebergs can here be studied to admirable advantage. during the month in which we encamped in the vicinity the process was going on continuously. there was scarcely an interval of fifteen minutes during the whole time in which the air was not rent with the significant boom connected with the "calving" of a berg. sometimes this was occasioned by the separation of a comparatively small mass of ice from near the top of the precipitous wall, which would fall into the water below with a loud splash. at other times i have seen a column of ice from top to bottom of the precipice split off and fall over into the water, giving rise to great waves, which would lash the shore with foam two miles below. this manner of the production of icebergs differs from that which has been ordinarily represented in the text-books, but it conforms to the law of glacial motion, which we will describe a little later, namely, that the upper strata of ice move faster than the lower. hence the tendency is constantly to push the upper strata forwards, so as to produce a perpendicular or even projecting front, after the analogy of the formation of breakers on the shelving shore of a large body of water. evidently, however, these masses of ice which break off from above the water do not reach the whole distance to the bottom of the glacier below the water; so that a projecting foot of ice remains extending to an indefinite distance underneath the surface. but at occasional intervals, as the superincumbent masses of ice above the surface fall off and relieve the strata below of their weight, these submerged masses suddenly rise, often shooting up considerably higher than they ultimately remain when coming to rest. the bergs formed by this latter process often bear much earthy material upon them, which is carried away with the floating ice, to be deposited finally wherever the melting chances to take place. numerous opportunities are furnished about the front and foot of this vast glacier to observe the manner of the formation of _kames_, kettle-holes, and various other irregular forms into which glacial _débris_ is accustomed to accumulate. over portions of the decaying foot of the glacier, which was deeply covered with morainic _débris_, the supporting ice is being gradually removed through the influence of subglacial streams or of abandoned tunnels, which permit the air to exert its melting power underneath. in some places where old _moulins_ had existed, the supporting ice is melting away, so that the superincumbent mass of sand, gravel, and boulders is slowly sliding into a common centre, like grain in a hopper. this must produce a conical hill, to remain, after the ice has all melted away, a mute witness of the impressive and complicated forces which have been so long in operation for its production. in other places i have witnessed the formation of a long ridge of gravel by the gradual falling in of the roof of a tunnel which had been occupied by a subglacial stream, and over which there was deposited a great amount of morainic material. as the roof gave way, this was constantly falling to the bottom, where, being exempt from further erosive agencies, it must remain as a gravel ridge or kame. in other places, still, there were vast masses of ice covering many acres, and buried beneath a great depth of morainic material which had been swept down upon it while joined to the main glacier. in the retreat of the ice, however, these masses had become isolated, and the sand, gravel, and boulders were sliding down the wasting sides and forming long ridges of _débris_ along the bottom, which, upon the final melting of the ice, will be left as a complicated network of ridges and knolls of gravel, enclosing an equally complicated nest of kettle-holes. beyond cross sound the pacific coast is bounded for several hundred miles by the magnificent semicircle of mountains known as the st. elias alps, with mount crillon at the south, having an elevation of nearly sixteen thousand feet, and st. elias in the centre, rising to a greater height. everywhere along this coast, as far as the alaskan peninsula, vast glaciers come down from the mountain-sides, and in many cases their precipitous fronts form the shore-line for many miles at a time. icy bay, just to the south of mount st, elias, is fitly named, on account of the extent of the glaciers emptying into it and the number of icebergs cumbering its waters. in the summer of a party, under the lead of mr. i. c. russell, of the united states geological survey, made an unsuccessful attempt to scale the heights of mount st. elias; but the information brought back by them concerning the glaciers of the region amply repaid them for their toil and expense, and consoled them for the failure of their immediate object. [illustration: fig. .--by the courtesy of the national geographical society.] leaving yakutat bay, and following the route indicated upon the accompanying map, they travelled on glacial ice almost the entire distance to the foot of mount st. elias. the numerous glaciers coming down from the summit of the mountain-ridge become confluent nearer the shore, and spread out over an area of about a thousand square miles. this is fitly named the malaspina glacier, after the spanish explorer who discovered it in . it is not necessary to add further particulars concerning the results of this expedition, since they are so similar to those already detailed in connection with the muir glacier. a feature, however, of special interest, pertains to the glacial lakes which are held in place by the glacial ice at an elevation of thousands of feet above the sea. one of considerable size is indicated upon the map just south of what was called blossom island, which, however, is not an island, but simply a _nunatak_, the ice here surrounding a considerable area of fertile land, which is covered with dense forests and beautified by a brilliant assemblage of flowering plants. in other places considerable vegetation was found upon the surface of moraines, which were probably still in motion with the underlying ice. _greenland._--the continental proportions of greenland, and the extent to which its area is covered by glacial ice, make it by far the most important accessible field for glacial observations. the total area of greenland can not be less than five hundred thousand square miles--equal in extent to the portion of the united states east of the mississippi and north of the ohio. it is now pretty evident that the whole of this area, except a narrow border about the southern end, is covered by one continuous sheet of moving ice, pressing outward on every side towards the open water of the surrounding seas. for a long time it was the belief of many that a large region in the interior of greenland was free from ice, and was perhaps inhabited. it was in part to solve this problem that baron nordenskiöld set out upon his expedition of . ascending the ice-sheet from disco bay, in latitude °, he proceeded eastward for eighteen days across a continuous ice-field. rivers were flowing in channels upon the surface like those cut on land in horizontal strata of shale or sandstone, only that the pure deep blue of the ice-walls was, by comparison, infinitely more beautiful. these rivers were not, however, perfectly continuous. after flowing for a distance in channels on the surface, they, one and all, plunged with deafening roar into some yawning crevasse, to find their way to the sea through subglacial channels. numerous lakes with shores of ice were also encountered. [illustration: fig. .--map of greenland. the arrow-points mark the margin of the ice-field.] "on bending down the ear to the ice," says this explorer, "we could hear on every side a peculiar subterranean hum, proceeding from rivers flowing within the ice; and occasionally a loud, single report, like that of a cannon, gave notice of the formation of a new glacier-cleft.... in the afternoon we saw at some distance from us a well-defined pillar of mist, which, when we approached it, appeared to rise from a bottomless abyss, into which a mighty glacier-river fell. the vast, roaring water-mass had bored for itself a vertical hole, probably down to the rock, certainly more than two thousand feet beneath, on which the glacier rested."[aj] [footnote aj: geological magazine, vol. ix, pp. , .] at the end of the eighteen days nordenskiöld found himself about a hundred and fifty miles from his starting-point, and about five thousand feet above the sea. here the party rested, and sent two eskimos forward on _skidor_--a kind of long wooden skate, with which they could move rapidly over the ice, notwithstanding the numerous small, circular holes which everywhere pitted the surface. these eskimos were gone fifty-seven hours, having slept only four hours of the period. it is estimated that they made about a hundred and fifty miles, and attained an altitude of six thousand feet. the ice is reported as rising in distinct terraces, and as seemingly boundless beyond. if this is the case, two hundred miles from disco bay, there would seem little hope of finding in greenland an interior freed from ice. so we may pretty confidently speak of that continental body of land as still enveloped in an ice-sheet. up to about latitude °, however, the continent is fringed by a border of islands, over which there is no continuous covering of ice. in south greenland the continuous ice-sheet is reached about thirty miles back from the shore. a summary of the results of greenland exploration was given by dr. kink in , from which it appears that since one thousand miles of the coast-line have been carefully explored by entering every fiord and attempting to reach the inland ice. according to this authority-- we are now able to demonstrate that a movement of ice from the central regions of greenland to the coast continually goes on, and must be supposed to act upon the ground over which it is pushed so as to detach and transport fragments of it for such a distance.... the plainest idea of the ice-formation here in question is given by comparing it with an inundation.... only the marginal parts show irregularity; towards the interior the surface grows more and more level and passes into a plain very slightly rising in the same direction. it has been proved that, ascending its extreme verge, where it has spread like a lava-stream over the lower ground in front of it, the irregularities are chiefly met with up to a height of , feet, but the distance from the margin in which the height is reached varies much. while under - / ° north latitude it took twenty-four miles before this elevation was attained, in - / ° the same height was arrived at in half the distance.... a general movement of the whole mass from the central regions towards the sea is still continued, but it concentrates its force to comparatively few points in the most extraordinary degree. these points are represented by the ice-fiords, through which the annual surplus ice is carried off in the shape of bergs.... in danish greenland are found five of the first, four of the second, and eight of the third (or least productive) class, besides a number of inlets which only receive insignificant fragments. direct measurements of the velocity have now been applied on three first-rate and one second-rate fiords, all situated between ° and ° north latitude. the measurements have been repeated during the coldest and the warmest season, and connected with surveying and other investigations of the inlets and their environs. it is now proved that the glacier branches which produce the bergs proceed incessantly at a rate of thirty to fifty feet per diem, this movement being not at all influenced by the seasons. . . . in the ice-fiord of jakobshavn, which spreads its enormous bergs over disco bay and probably far into the atlantic, the productive part of the glacier is , metres (about - / miles) broad. the movement along its middle line, which is quicker than on the sides nearer the shores, can be rated at fifty feet per diem. the bulk of ice here annually forced into the sea would, if taken on the shore, make a mountain two miles long, two miles broad, and , feet high. the ice-fiord of torsukatak receives four or five branches of the glacier; the most productive of them is about , metres broad (five miles), and moves between sixteen and thirty-two feet per diem. the large karajak glacier, about , metres (four miles) broad, proceeds at a rate of from twenty-two to thirty-eight feet per diem. finally, a glacier branch dipping into the fiord of jtivdliarsuk, , metres broad (three miles), moved between twenty-four and forty-six feet per diem.[ak] [footnote ak: see transactions of the edinburgh geological society for february , , vol. v, part ii, pp. - .] the principal part of our information concerning the glaciers of greenland north of melville bay was obtained by drs. kane and hayes, in and , while conducting an expedition in search of sir john franklin and his unfortunate crew. dr. hayes conducted another expedition to the same desolate region in , while other explorers have to some extent supplemented their observations. the largest glacier which they saw enters the sea between latitude ° and °, where it presents a precipitous discharging front more than sixty miles in width and hundreds of feet in perpendicular height. dr. kane gives his first impressions of this grand glacier in the following vivid description: "i will not attempt to do better by florid description. men only rhapsodize about niagara and the ocean. my notes speak simply of the 'long, ever-shining line of cliff diminished to a well-pointed wedge in the perspective'; and, again, of 'the face of glistening ice, sweeping in a long curve from the low interior, the facets in front intensely illuminated by the sun.' but this line of cliff rose in a solid, glassy wall three hundred feet above the water-level, with an unknown, unfathomable depth below it; and its curved face, sixty miles in length from cape agassiz to cape forbes, vanished into unknown space at not more than a single day's railroad-travel from the pole. the interior, with which it communicated and from which it issued, was an unsurveyed _mer de glace_--an ice-ocean to the eye, of boundless dimensions. "it was in full sight--the mighty crystal bridge which connects the two continents of america and greenland. i say continents, for greenland, however insulated it may ultimately prove to be, is in mass strictly continental. its least possible axis, measured from cape farewell to the line of this glacier, in the neighbourhood of the eightieth parallel, gives a length of more than , miles, not materially less than that of australia from its northern to its southern cape. "imagine, now, the centre of such a continent, occupied through nearly its whole extent by a deep, unbroken sea of ice that gathers perennial increase from the water-shed of vast snow-covered mountains and all the precipitations of its atmosphere upon its own surface. imagine this, moving onwards like a great glacial river, seeking outlets at every fiord and valley, rolling icy cataracts into the atlantic and greenland seas; and, having at last reached the northern limit of the land that has borne it up, pouring out a mighty frozen torrent into unknown arctic space! "it is thus, and only thus, that we must form a just conception of a phenomenon like this great glacier. i had looked in my own mind for such an appearance, should i ever be fortunate enough to reach the northern coast of greenland; but, now that it was before me, i could hardly realize it. i had recognized, in my quiet library at home, the beautiful analogies which forbes and studer have developed between the glacier and the river. but i could not comprehend at first this complete substitution of ice for water. "it was slowly that the conviction dawned on me that i was looking upon the counterpart of the great river-system of arctic asia and america. yet here were no water-feeders from the south. every particle of moisture had its origin within the polar circle and had been converted into ice. there were no vast alluvions, no forest or animal traces borne down by liquid torrents. here was a plastic, moving, semi-solid mass, obliterating life, swallowing rocks and islands, and ploughing its way with irresistible march through the crust of an investing sea."[al] [footnote al: arctic explorations in the years , , and , vol. i, pp. - .] much less is known concerning the eastern coast of greenland than about the western coast. for a long time it was supposed that there might be a considerable population in the lower latitudes along the eastern side. but that is now proved to be a mistake. the whole coast is very inhospitable and difficult of approach. from latitude ° to latitude ° little or nothing is known of it. in -' scoresby, cleavering, and sabine hastily explored the coast from latitude ° to °, and reported numerous glaciers descending to the sea-level through extensive fiords, from which immense icebergs float out and render navigation dangerous. in and the second north-german expedition partly explored the coast between latitude ° and °. mr. payer, an experienced alpine explorer, who accompanied the expedition, reports the country as much broken, and the glaciers as "subordinated in position to the higher peaks, and having their moraines, both lateral and terminal, like those of the alpine ranges, and on a still grander scale." petermann peak, in latitude °, is reported as , feet high. captain koldewey, chief of the expedition, found extensive plateaus on the mainland, in latitude °, to be "entirely clear of snow, although only sparsely covered with vegetation." the mountains in this vicinity, also, rising to a height of more than , feet, were free from snow in the summer. some of the fiords in this vicinity penetrate the continent through several degrees of longitude. an interesting episode of this expedition was the experience of the crew of the ship hansa, which was caught in the ice and destroyed. the crew, however, escaped by encamping on the ice-floe which had crushed the ship. from this, as it slowly floated towards the south through several degrees of latitude, they had opportunity to make many important observations upon the continent itself. as viewed from this unique position the coast had the appearance everywhere of being precipitous, with mountains of considerable height rising in the background, from which numerous small glaciers descended to the sea-level. in dr. f. nansen, with lieutenant sverdrup and four others, was left by a whaler on the ice-pack bordering the east of greenland about latitude °, and in sight of the coast. for twelve days the party was on the ice-pack floating south, and so actually reached the coast only about latitude °. from this point they attempted to cross the inland ice in a northwesterly direction towards christianshaab. they soon reached a height of , feet, and were compelled by severe northerly storms to diverge from their course, taking a direction more to the west. the greatest height attained was , feet, and the party arrived on the western coast at ameralik fiord, a little south of godhaab, about the same latitude at which they entered. it thus appears that subsequent investigations have confirmed in a remarkable manner the sagacious conclusions made by the eminent scotch geologist and glacialist robert brown in , soon after his own expedition to the country. "i look upon greenland and its interior ice-field," he writes, "in the light of a broad-lipped, shallow vessel, but with chinks in the lips here and there, and the glacier like viscous matter in it. as more is poured in, the viscous matter will run over the edges, naturally taking the line of the chinks as its line of outflow. the broad lips of the vessel are the outlying islands or 'outskirts'; the viscous matter in the vessel the inland ice, the additional matter continually being poured in in the form of the enormous snow covering, which, winter after winter, for seven or eight months in the year, falls almost continuously on it; the chinks are the fiords or valleys down which the glaciers, representing the outflowing viscous matter, empty the surplus of the vessel--in other words, the ice floats out in glaciers, overflows the land in fact, down the valleys and fiords of greenland by force of the superincumbent weight of snow, just as does the grain on the floor of a barn (as admirably described by mr. jamieson) when another sackful is emptied on the top of the mound already on the floor. 'the floor is flat, and therefore does not conduct the grain in any direction; the outward motion is due to the pressure of the particles of grain on one another; and, given a floor of infinite extension and a pile of sufficient amount, the mass would move outward to any distance, and with a very slight pitch or slope it would slide forward along the incline.' to this let me add that if the floor on the margin of the heap of grain was undulating the stream of grain would take the course of such undulations. the want, therefore, of much slope in a country and the absence of any great mountain-range are of very little moment to the movement of land-ice, _provided we have snow enough_" on another page dr. brown had well said that "the country seems only a circlet of islands separated from one another by deep fiords or straits, and bound together on the landward side by the great ice covering which overlies the whole interior.... no doubt under this ice there lies land, just as it lies under the sea; but nowadays none can be seen, and as an insulating medium it might as well be water." in his recently published volumes descriptive of the journey across the greenland ice-sheet, alluded to on page , dr. nansen sums up his inferences in very much the same way: "the ice-sheet rises comparatively abruptly from the sea on both sides, but more especially on the east coast, while its central portion is tolerably flat. on the whole, the gradient decreases the farther one gets into the interior, and the mass thus presents the form of a shield with a surface corrugated by gentle, almost imperceptible, undulations lying more or less north and south, and with its highest point not placed symmetrically, but very decidedly nearer the east coast than the west." from this rapid glance at the existing glaciers of the world we see that a great ice age is not altogether a strange thing in the world. the lands about the south pole and greenland are each continental in dimensions, and present at the present time accumulations of land-ice so extensive, so deep, and so alive with motion as to prepare our minds for almost anything that may be suggested concerning the glaciated condition of other portions of the earth's surface. the _vera causa_ is sufficient to accomplish anything of which glacialists have ever dreamed. it only remains to enquire what the facts really are and over how great an extent of territory the actual results of glacial action may be found. but we will first direct more particular attention to some of the facts and theories concerning glacial motion. chapter iii. glacial motion. that glacial ice actually moves after the analogy of a semi-fluid has been abundantly demonstrated by observation. in the year professor hugi, of soleure, built a hut far up upon the aar glacier in switzerland, in order to determine the rate of its motion. after three years he found that it had moved feet; after nine years, , feet; and after fourteen years louis agassiz found that its motion had been , feet. in agassiz began a more accurate series of observation upon the same glacier. boring holes in the ice, he set across it a row of stakes which, on visiting in , he found to be no longer in a straight line. all had moved downwards with varying velocity, those near the centre having moved farther than the others. the displacements of the stakes were in order, from side to side, as follows: feet, feet, feet, feet, feet, and feet. agassiz followed up his observations for six years, and in published the results in his celebrated work system glacière. [illustration: fig. .] but in august, , the distinguished swiss investigator had invited professor j. d. forbes, of edinburgh, to interest himself in solving the problem of glacial motion. in response to this request, professor forbes spent three weeks with agassiz upon the aar glacier. stimulated by the interest of this visit, forbes returned to switzerland in and began a series of independent investigations upon the mer de glace. after a week's observations with accurate instruments, forbes wrote to professor jameson, editor of the edinburgh new philosophical journal, that he had already made it certain that "the central part of the glacier moves faster than the edges in a very considerable proportion, quite contrary to the opinion generally maintained." this letter was dated july , , but was not published until the october following, agassiz's results, so far as then determined, were, however, published in comptes rendus of the th of august, , two months before the publication of forbes's letter. but agassiz's letter was dated twenty-seven days later than that of forbes. it becomes certain, therefore, that both agassiz and forbes, independently and about the same time, discovered the fact that the central portion of a glacier moves more rapidly than the sides. in professor tyndall began his systematic and fruitful observations upon the mer de glace and other alpine glaciers. professor forbes had already demonstrated that, with an accurate instrument of observation, the motion of a line of stakes might be observed after the lapse of a single clay, or even of a few hours. as a result of tyndall's observations, it was found that the most rapid daily motion in the mer de glace in was about thirty-seven inches. this amount of motion was near the lower end of the glacier on ascending the glacier, the rate was found in general to be diminished; but the diminution was not uniform throughout the whole distance, being affected both by the size and by the contour of the valley. the motion in the tributary glaciers was also much less than that of the main glacier. this diminution of movement in the tributary glaciers was somewhat proportionate to their increase in width. for example, the combined width of the three tributaries uniting to form the mer de glace is , yards; but a short distance below the junction of these tributaries the total width of the mer de glace itself is only yards, or one-third that of the tributaries combined. yet, though the depth of the ice is probably here much greater than in the tributaries, the rapidity of movement is between two and three times as great as that of any one of the branches.[am] [footnote am: see tyndall's forms of water, pp. - .] from tyndall's observations it appears also that the line of most rapid motion is not exactly in the middle of the channel, but is pushed by its own momentum from one side to the other of the middle, so as always to be nearer the concave side; in this respect conforming, as far as its nature will permit, to the motion of water in a tortuous channel. [illustration: fig. .] it is easy to account for this differential motion upon the surface of a glacier, since it is clear that the friction of the sides of the channel must retard the motion of ice as it does that of water. it is clear also that the friction of the bottom must retard the motion of ice even more than it is known to do in the case of water. in the formation of breakers, when the waves roll in upon a shallowing beach, every one is familiar with the effect of the bottom upon the moving mass. here friction retards the lower strata of water, and the upper strata slide over the lower, and, where the water is of sufficient depth and the motion is sufficiently great, the crest breaks down in foam before the ever-advancing tide. a similar phenomenon occurs when dams give way and reservoirs suddenly pour their contents into the restricted channels below. at such times the advancing water rolls onwards like the surf with a perpendicular front, varying in height according to the extent of the flood. seasoning from these phenomena connected with moving water, it was naturally suggested to professor tyndall that an analogous movement must take place in a glacier. choosing, therefore, a favourable place for observation on the mer de glace where the ice emerged from a gorge, he found a perpendicular side about one hundred and fifty feet in height from bottom to top. in this face he drove stakes in a perpendicular line from top to bottom. upon subsequently observing them, tyndall found, as he expected, that there was a differential motion among them as in the stakes upon the surface. the retarding effect of friction upon the bottom was evident. the stake near the top moved forwards about three times as fast as the one which was only four feet from the bottom. [illustration: fig. .] the most rapid motion (thirty-seven inches per day) observed by professor tyndall upon the alpine glaciers occurred in midsummer. in winter the rate was only about one-half as great; but in the year the norwegian geologist, helland, reported a movement of twenty metres (about sixty-five feet) per day in the jakobshavn glacier which enters disco bay, greenland, about latitude °. for some time there was a disposition on the part of many scientific men to doubt the correctness of holland's calculations. subsequent observations have shown, however, that from the comparatively insignificant glaciers of the alps they were not justified in drawing inferences with respect to the motion of the vastly larger masses which come down to the sea through the fiords of greenland. the jakobshavn glacier was about two and a half miles in width and its depth very likely more than a thousand feet, making a cross-section of more than , , square yards, whereas the cross-section of the mer de glace at montanvert is estimated to be but , square yards or only about one-seventh the above estimate for the greenland glacier. as the friction of the sides would be no greater upon a large stream than upon a small one, while upon the bottom it would be only in proportion to the area, it is evident that we cannot tell beforehand how rapidly an increase in the volume of the ice might augment the velocity of the glacier. at any rate, all reasonable grounds for distrusting the accuracy of helland's estimates seem to have been removed by later investigations. according to my own observations in the summer of upon the muir glacier, alaska, the central portions, a mile back from the front of that vast ice-current, were moving from sixty-five to seventy feet per day. these observations were taken with a sextant upon pinnacles of ice recognizable from a baseline established upon the shore. it is fair to add, however, that during the summer of professor h. f. reid attempted to measure the motion of the same glacier by methods promising greater accuracy than could be obtained by mine. he endeavoured to plant, after the method of tyndall, a line of stakes across the ice-current. but with his utmost efforts, working inwards from both sides, he was unable to accomplish his purpose, and so left unmeasured a quarter of a mile or more of the most rapidly-moving portion of the glacier. his results, therefore, of ten feet per day in the most rapidly-moving portion observed cannot discredit my own observations on a portion of the stream inaccessible by his method. a quarter of a mile in width near the centre of so vast a glacier gives ample opportunity for a much greater rate of motion than that observed by professor reid. especially may this be true in view of tyndall's suggestion that the contour of the bottom over which the ice flows may greatly affect the rate in certain places. a sudden deepening of the channel may affect the motion of ice in a glacier as much as it does that of water in a river. other observations also amply sustain the conclusions of helland. as already stated, the danish surveying party under steenstrup, after several years' work upon the southwestern coast of greenland, have ascertained that the numerous glaciers coming down to the sea in that region and furnishing the icebergs incessantly floating down baffin's bay, move at a rate of from thirty to fifty feet per day, while lieutenants ryder and bloch, of the danish navy, who spent the year in exploring the coast in the vicinity of upernavik, about latitude °, found that the great glacier entering the fiord east of the village had a velocity of ninety-nine feet per day during the month of august.[an] [footnote an: nature, december , .] it is easier to establish the fact of glacial motion than to explain how the motion takes place, for ice seems to be as brittle as glass. this, however, is true of it only when compelled suddenly to change its form. when subjected to slow and long-continued pressure it gradually yet readily yields, and takes on new forms. from this capacity of ice, it has come to be regarded by some as a really viscous substance, like tar or cooling lava, and upon that theory professor forbes endeavours to explain all glacial movement. the theory, however, seems to be contradicted by familiar facts; for the iceman, after sawing a shallow groove across a piece of ice, can then split it as easily as he would a piece of sandstone or wood. on the glaciers themselves, likewise, the existence of innumerable crevasses would seem to contradict the plastic theory of glacier motion; for, wherever the slope of the glacier's bed increases, crevasses are formed by the increased strain to which the ice is subjected. crevasses are also formed in rapidly-moving glaciers by the slight strain occasioned by the more rapid motion of the middle portion. still, in the words of tyndall, "it is undoubted that the glacier moves like a viscous body. the centre flows past the sides, the top flows over the bottom, and the motion through a curved valley corresponds to fluid motion."[ao] [footnote ao: forms of water, p. .] to explain this combination of the seemingly contradictory qualities of brittleness and viscosity in ice, physicists have directed attention to the remarkable transformations which take place in water at the freezing-point. faraday discovered in that "when two pieces of thawing ice are placed together they freeze together at the point of contact.[ap] [footnote ap: ibid., p. .] "place a number of fragments of ice in a basin of water and cause them to touch each other; they freeze together where they touch. you can form a chain of such fragments; and then, by taking hold of one end of the chain, you can draw the whole series after it. chains of icebergs are sometimes formed in this way in the arctic seas."[aq] [footnote aq: ibid., pp. , .] this is really what takes place when a hard snow-ball is made by pressure in the hand. so, by subjecting fragments of ice to pressure it is first crumbled to powder, and then, as the particles are pressed together in close contact, it resumes the nature of ice again, though in a different form, taking now the shape of the mould in which it has been pressed. thus it is supposed that, when the temperature of ice is near the melting-point, the pressure of the superincumbent mass may produce at certain points insensible disintegration, while, upon the removal of the pressure by change of position, regulation instantly takes place, and thus the phenomena which simulate plasticity are produced. as the freezing-point of water is, within a narrow range, determined by the amount of pressure to which it is subjected, it is not difficult to see how these changes may occur. pressure slightly lowers the freezing-point, and so would liquefy the portions of ice subjected to greatest pressure, wherever that might be in the mass of the glacier, and thus permit a momentary movement of the particles, until they should recongeal in adjusting themselves to spaces of less pressure.[ar] this is the theory by which professor james thompson would account for the apparent plasticity of glacial ice. [footnote ar: forms of water, p. .] chapter iv. signs of past glaciation. the facts from which we draw the inference that vast areas of the earth's surface which are now free from glaciers were, at a comparatively recent time, covered with them, are fourfold, and are everywhere open to inspection. these facts are: . scratches upon the rocks. . extensive unstratified deposits of clay and sand intermingled with scratched stones and loose fragments of rock. . transported boulders left in such positions and of such size as to preclude the sufficiency of water-carriage to account for them. . extensive gravel terraces bordering the valleys which emerge from the glaciated areas. we will consider these in their order: . the scratches upon the rocks. almost anywhere in the region designated as having been covered with ice during the glacial period, the surface of the rocks when freshly uncovered will be found to be peculiarly marked by grooves and scratches more or less fine, and such as could not be produced by the action of water. but, when we consider the nature of a glacier, these marks seem to be just what would be produced by the pushing or dragging along of boulders, pebbles, gravel, and particles of sand underneath a moving mass of ice. running water does indeed move gravel, pebbles, and boulders along with the current, but these objects are not held by it in a firm grasp, such as is required to make a groove or scratch in the rock. if, also, there are inequalities in the compactness or hardness of the rock, the natural action of running water is to hollow out the soft parts, and leave the harder parts projecting. but, in the phenomena which we are attributing to glacial action, there has been a movement which has steadily planed down the surface of the underlying rock; polishing it, indeed, but also grooving it and scratching it in a manner which could be accomplished only by firmly held graving-tools. [illustration: fig. .--bed-rock scored with glacial marks, near amherst, ohio. (from a photograph by chamberlin.)] this polishing and scratching can indeed be produced by various agencies; as, for example, by the forces which fracture the earth's crust, and shove one portion past another, producing what is called a _slicken-side_. or, again, avalanches or land-slides might be competent to produce the results over limited and peculiarly situated areas. icebergs, also, and shore ice which is moved backwards and forwards by the waves, would produce a certain amount of such grooving and scratching. but the phenomena to which we refer are so extensive, and occur in such a variety of situations, that the movement of glacial ice is alone sufficient to afford a satisfactory explanation. moreover, in alaska, greenland, norway, and switzerland, and wherever else there are living glaciers, it is possible to follow up these grooved and striated surfaces till they disappear underneath the existing glaciers which are now producing the phenomena. thus by its tracks we can, as it were, follow this monster to its lair with as great certainty as we could any animal with whose footprints we had become familiar. . the till, or boulder-clay. a second sign of the former existence of glaciers over any area consists of an unstratified deposit of earthy material, of greater or less depth, in which scratched pebbles and fragments of rock occur without any definite arrangement. moving water is a most perfect sieve. during floods, a river shoves along over its bed gravel and pebbles of considerable size, whereas in time of low-water the current may be so gentle as to transport nothing but fine sand, and the clay will be carried still farther onwards, to settle in the still water and form a delta about the river's mouth. the transporting capacity of running water is in direct ratio to the sixth power of its velocity. other things being equal, if the velocity be doubled, the size of the grains of sand or gravel which it transports is increased sixty-four fold.[as] so frequent are the changes in the velocity of running water, that the stratification of its deposits is almost necessary and universal. if large fragments of rocks or boulders are found embedded in stratified clay, it is pretty surely a sign that they have been carried to their position by floating ice. a small mountain stream with great velocity may move a good-sized boulder, while the amazon, with its mighty but slow-moving current, would pass by it forever without stirring it from its position. but the vast area which is marked in our map as having been covered with ice during the glacial period is characterised by deep and extensive deposits of loose material devoid of stratification, and composed of soil and rock gathered in considerable part from other localities, and mixed in an indiscriminate mass with material which has originated in the disintegration of the underlying local strata. [footnote as: le conte's geology, p. .] [illustration: fig. .--scratched stone from the till of boston. natural size about one foot and a half long by ten inches wide. (from photograph.)] [illustration: fig. .--typical section of till in seattle. washington state, about two hundred feet above puget sound. this is on the height between the sound and lake washington.] [illustration: fig. .--ideal section, showing how the till overlies the stratified rocks.] [illustration: fig. .--vessel rock, a glacial boulder in gilsum. n. h. (c. h. hitchcock.)] . transported boulders. where there is a current of water deep enough to float large masses of ice, there is scarcely any limit to the size of boulders which may be transported upon them, or to the distance to which the boulders may be carried and dropped upon the bottom. the icebergs which break off from the glaciers of greenland may bear their burdens of rock far down into the atlantic, depositing them finally amidst the calcareous ooze and the fine sediment from the gulf stream which is slowly covering the area between northern america and europe. northern streams like the st. lawrence, which are deeply frozen over with ice in the winter, and are heavily flooded as the ice breaks up in the spring, afford opportunity for much transportation of boulders in the direction of their current. in attributing the transportation of a boulder to glacial ice, it is necessary, therefore, to examine the contour of the country, so as to eliminate from the problem the possibility of the effects having been produced by floating ice. another source of error against which one has to be on his guard arises from the close resemblance of boulders resulting from disintegration to those which have been transported by ice from distant places. owing to the fact that large masses of rocks, especially those which are crystalline, are seldom homogeneous in their structure, it results that, under the slow action of disintegrating and erosive agencies, the softer parts often are completely removed before the harder nodules are sensibly affected, and these may remain as a collection of boulders dotting the surface. such boulders are frequent in the granitic regions of north carolina and vicinity, where there has been no glacial transportation. several localities in pennsylvania, also, south of the line of glacial action as delineated by professor lewis and myself, had previously been supposed to contain transported boulders of large size, but on examination they proved in all cases to be resting upon undisturbed strata of the parent rock, and were evidently the harder portions of the rock left in loco by the processes of erosion spoken of. in new england, also, it is possible that some boulders heretofore attributed to ice-action may be simply the results of these processes of disintegration and erosion. whether they are or not can usually be determined by their likeness or unlikeness to the rocks on which they rest; but oftentimes, where a particular variety of rock is exposed over a broad area, it is difficult to tell whether a boulder has suffered any extensive transportation or not. one of the most interesting and satisfactory demonstrations of the distribution of boulders by glacial ice was furnished by guyot in switzerland in . his observations and argument will be most readily understood by reference to the accompanying map, taken from lyell's clear description.[at] the jura mountains are separated from the alps by a valley, about eighty miles in width, which constitutes the main habitable portion of switzerland, and they rise upwards of two thousand feet above it. but large alpine boulders are found as high as two thousand feet above the lake neufchâtel upon the flanks of the jura mountains beyond chasseron (at the point marked g on the map), and the whole valley is dotted with alpine boulders. upon comparing these with the native rocks in the alps, guyot in many cases was able to determine the exact centres from which they were distributed, and the distribution is such as to demonstrate that glacial ice was the medium of distribution. [footnote at: antiquity of man, p. .] [illustration: fig. .--map showing the outline and course of flow of the great rhône glacier (after lyell).] for example, the dotted lines upon the map indicate the motion of the transporting medium. on ascending the valley of the rhône to a, the diminutive representative of the ancient glacier is still found in existence, and is at work transporting boulders and moraines according to the law of ice-movement. following down the valley from a, boulders from the head of the rhône valley are found distributed as far as b at martigny, where the valley turns at right angles towards the north. it is evident that floating ice in a stream of water would by its momentum be carried to the left bank, so that if icebergs were the medium of transportation we should expect to find the boulders from the right-hand side of the rhône valley distributed towards the left end of the great valley of switzerland--that is, in the direction of geneva. but, instead, the boulders derived from c, d, and e, on the bernese oberland side, instead of crossing the valley at b, continue to keep on the right-hand side and are distributed over the main valley in the direction of the river aar. as is to be expected also, the direct northward motion of the ice from b is stronger than the lateral movement to the right and left after it emerges from the mouth of the rhône valley, at f, and consequently it has pushed forwards in a straight line, so as to raise the alpine boulders to a greater height upon the jura mountains at g than anywhere else, the upper limit of boulders at g being , feet higher than the limits at i or k on the left and right, points distant about one hundred miles from each other. all the boulders to the right of the line from b to g have been derived from the right side of the rhône, while all the boulders to the left of that line have been derived from its left side. a boulder of talcose granite containing , french cubic feet, measuring about forty feet in one direction, came, according to charpentier, from the point _n_, near the head of the rhône valley, and must have travelled one hundred and fifty miles to reach its present position. it scarcely needs to be added that the grooves and scratches upon the rocks over the floor of this great valley of switzerland indicate a direction of the ice-movement corresponding to that implied in the distribution of boulders. thus, at k upon the map referred to, lyell reports that the abundant grooves and striæ upon the polished marble all trend down the valley of the aar.[au] [footnote au: antiquity of man, p. .] similar facts concerning the transportation of boulders have been observed at trogen, in appenzel, where boulders derived from trons, one hundred miles distant, are found to keep upon the left bank of the rhine, however much the valley may wind about; and in some places, as at mayenfeld, it turns almost at right angles, as did the rhône at martigny. upon reaching the lower country at lake constance, these granite blocks from the left side of the valley deploy out upon the same side and do not cross over, as they would inevitably have done had they been borne along by currents of water. in america ave do not have quite so easy a field as is presented in switzerland for the discovery of crucial instances showing that boulders have been transported by glacial ice rather than by floating ice, for in switzerland the glaciated area is comparatively small and the diminutive remnants of former glaciers are still in existence, furnishing a comprehensive object-lesson of great interest and convincing power. still, it is not difficult to find decisive instances of glacial transportation even in the broad fields of america which now retain no living remnants of the great continental ice-sheet. as every one who resides in or who visits new england knows, boulders are scattered freely over all parts of that region, but for a long time the theory suggested to account for their distribution was that of floating ice during a period of submergence. one of the most convincing evidences that the boulders were distributed by glacial ice rather than by icebergs is found in professor c. h. hitchcock's discovery of boulders on the summit of mount washington (over , feet above the sea), which he was able to identify as derived from the ledges of light grey bethlehem gneiss, whose nearest outcrop is in jefferson, several miles to the northwest, and , or , feet lower than mount washington. however difficult it may be to explain the movement of these boulders by glacial ice, it is not impossible to do so, but the attempt to account for their transportation by floating ice is utterly preposterous. no iceberg could pick up boulders so far beneath the surface of the water, and even if it could advance thus far in its work it could not by any possibility land them afterwards upon the summit of mount washington. among the most impressive instances of boulders evidently transported by glacial ice, rather than by icebergs, were some which came to my notice when, in company with the late professor h. carvill lewis, i was tracing the glacial boundary across the state of pennsylvania. we had reached the elevated plateau (two thousand feet above the sea) which extends westwards and southwards from the peak of pocono mountain, in monroe county. this plateau consists of level strata of sandstone, the southern part of which is characterised by a thin sandy soil, such as is naturally formed by the disintegration of the underlying rock, and there is no foreign material to be found in it. but, on going northwards to the boundary of tobyhanna township, we at once struck a large line of accumulations, stretching from east to west, and rising to a height of seventy or eighty feet. this was chiefly an accumulation of transported boulders, resembling in its structure the terminal moraines which are found at the front of glaciers in the alps and in alaska, and indeed wherever active glaciers still remain. but here we were upon the summit of the mountain, where there are no higher levels to the north of us, down which the ice could flow. besides, among these boulders we readily recognised many of granite, which must have come either from the adirondack mountains, two hundred miles to the north, or from the canadian highlands, still farther away. limiting our observations simply to the boulders, we should indeed have been at liberty to suppose that they had been transported across the valley of the mohawk or of the great lakes by floating ice during a period of submergence. but we were forbidden to resort to this hypothesis by the abrupt marginal line, running east and west, upon pocono plateau, along which these northern boulders ceased. south of this evident terminal moraine there was no barrier, and there were no northern boulders. on the theory of submergence, there was no reason for the boundary-line so clearly manifested. ice which had floated so far would have floated farther. still further, on going a few miles east of the pocono plateau, one descends into a parallel valley, lying between pocono mountain and blue mountain, and one thousand feet below their level. but our marginal southern boundary of transported granite rocks did not extend much farther south in the valley than it did on the plateau, except where we could trace the action of a running stream, evidently corresponding to the subglacial rivers which pour forth from the front of every extensive glacier. in these facts, therefore, we had a crucial test of the glacial hypothesis, and, in view of them, could maintain, against all objectors, the theory of the distant glacial transportation of boulders, even over vast areas of the north american continent. since that experience, i have traced this limit of southern boulders for thousands of miles across the continent, according to the delineation which may be seen in the map in a later chapter. if necessary, i could indicate hundreds of places where the proof of glacial transportation is almost as clear as that on the pocono plateau in pennsylvania. one of the most interesting of these is on the hills in kentucky, about twelve miles south of the ohio river, at cincinnati, where i discovered boulders of a conglomerate containing many pebbles of red jasper, which can be identified as from a limited formation cropping out in canada, to the north of lake huron, six hundred or seven hundred miles distant. that this was transported by glacial ice, and not by floating ice, is evident from the fact that here, too, there was no barrier to the south, requiring deposits to cease at that point, and from the further fact that boulders of this material are found in increasing frequency all the way from kentucky to the parent ledges in canada. with reference to these boulders, as with reference to those found on the summit of mount washington, we can reason, also, that any northerly subsidence permitting a body of water to occupy the space between kentucky and lake superior, and deep enough to facilitate the movement across it of floating ice, would render it impossible for the ice to have loaded itself with them. [illustration: fig. .--conglomerate boulder found in boone county, kentucky. (see text.)] the same line of reasoning is conclusive respecting the innumerable boulders which cover the northern portion of ohio, where i have my residence. the whole state of ohio, and indeed almost the entire mississippi basin between the appalachian and the rocky mountains, is completely covered, and to a great depth, with stratified rocks which have been but slightly disturbed in the elevation of the continent; yet, down to an irregular border-line running east and west, granitic boulders everywhere occur in great numbers. in the locality spoken of in northern ohio the elevation of the country is from two hundred to five hundred feet above the level of lake erie. the nearest outcrops of granitic rock occur about four hundred miles to the north, in canada. after the meeting of the american association for the advancement of science in toronto in the summer of , i had the privilege of joining a company of geologists in an excursion, conducted by members of the canadian survey, to visit the region beyond lake nipissing, north of lake huron, where the ancient laurentian and huronian rocks are most typically developed. i took advantage of the trip to collect specimens of a great variety of the granites and gneisses and metamorphic schists and trap-rock of the region. on bringing them home i turned them over to the professor of geology, who at once set his class at work to see if they could match my fragments from canada with corresponding fragments from the boulders of the vicinity. to the great gratification, both of the pupils and myself, they were able to do so in almost every case; and so they might have done in any county or township to the south until reaching the limit of glacier action which i had previously mapped. here, at oberlin, on the north side of the water-shed, it is possible to imagine that we are on the southern border of an ancient lake upon whose bosom floating ice had brought these objects from their distant home in canada. but this theory would not apply to the portion of the state which is south of the water-shed and which slopes rapidly towards the gulf of mexico. yet the distribution of boulders is practically uniform over the glaciated area on both sides of the water-shed, constituting thus an indisputable proof of the glacial theory. th. as the significance of the gravel terraces which mark the lines of outward drainage from the glaciated area cannot well be indicated in a single paragraph, the reader is referred for further information upon this point to the general statements respecting them throughout the next chapter. chapter v. ancient glaciers in the western hemisphere. _new england._ in north america all the indubitable signs of glacial action are found over the entire area of new england, the southern coast being bordered by a double line of terminal moraines. the outermost of these appears in nantucket, martha's vineyard, no man's land, block island, and through the entire length of long island--from montauk point, through the centre of the island, to brooklyn, n. y., and thence across staten island to perth amboy in new jersey. the interior line is nearly parallel with the outer, and, beginning at the east end of cape cod, runs in a westerly direction to falmouth, and thence southwesterly through wood's holl, and the elizabeth islands--these being, indeed, but the unsubmerged portions of the moraine. on the mainland this interior line reappears near point judith, on the south shore of rhode island, and, running slightly south of west, serves to give character to the scenery at watch hill, and thence crops out in the sound as fisher and plum islands, and farther west forms the northern shore of long island to port jefferson. [illustration: map showing the glacial geology of the united states.] in these accumulations bordering the southern shore of new england, the characteristic marks of glacial action can readily be detected even by the casual observer, and prolonged examination will amply confirm the first impression. the material of which they are composed is, for the most part, foreign to the localities, and can be traced to outcrops of rock at the north. the boulders scattered over the surface of long island, for example, consist largely of granite, gneiss, hornblende, mica slate, and red sandstone, which are easily recognised as fragments from well-known quarries in connecticut, rhode island, and massachusetts; yet they have been transported bodily across long island sound, and deposited in a heterogeneous mass through the entire length of the island. not only do they lie upon the surface, but, in digging into the lines of hills which constitute the backbone of long island, these transported boulders are found often to make up a large part of the accumulation. almost any of the railroad excavations in the city of brooklyn present an interesting object-lesson respecting the composition of a terminal moraine. all these things are true also of the lines of moraine farther east, as just described. professor shaler has traced to its source a belt of boulders occurring extensively over southern rhode island, and found that they have spread out pretty evenly over a triangular area to the southward, in accordance with the natural course to be pursued by an ice-movement. nearly all of plymouth county, in southeastern massachusetts, is composed of foreign material, much of which can be traced to the hills and mountains to the north. even plymouth rock is a boulder from the direction of boston, and the "rock-bound" shores upon which the pilgrims are poetically conceived to have landed are known, in scientific prose, as piles of glacial rubbish dumped into the edge of the sea by the great continental ice-sheet. the whole area of southeastern massachusetts is dotted with conical knolls of sand, gravel, and boulders, separated by circular masses of peat or ponds of water, whose origin and arrangement can be accounted for only by the peculiar agency of a decaying ice-front. indeed, this whole line of moraines, from the end of cape cod to brooklyn, n. y., consists of a reticulated network of ridges and knolls, so deposited by the ice as to form innumerable kettle-holes which are filled with water where other conditions are favourable. those which are dry are so because of their elevation above the general level, and of the looseness of the surrounding soil; while many have been filled with a growth of peat, so that their original character as lakelets is disguised. as already described, these depressions, so characteristic of the glaciated region, are, in the majority of cases, supposed to have originated by the deposition of a great quantity of earthy material around and upon the masses of ice belonging to the receding front of the glacier, so that, when at length the ice melted away, a permanent depression in the soil was left, without any outlet. to some extent, however, the kettle-holes may have been formed by the irregular deposition of streams of water whose courses have crossed each other, or where eddies of considerable force have been produced in any way. the ordinary formation of kettle-holes can be observed in progress on the foot of almost any glacier, or, indeed, on a small scale, during the melting away of almost any winter's snow. where, from any cause, a stratum of dirt has accumulated upon a mass of compact snow or ice, it will be found to settle down in an irregular manner; furrows will be formed in various directions by currents of water, so that the melting will proceed irregularly, and produce upon a miniature scale exactly what i have seen on a large scale over whole square miles of the decaying foot of the great muir glacier in alaska. the effects of similar causes and conditions we can see on a most enormous scale in the ten thousand lakes and ponds and peat-bogs of the whole glaciated area both in north america and in europe. in addition to these two lines of evidence of glacial action in new england, we should mention also the innumerable glacial grooves and scratches upon the rocks which can be found on almost any freshly uncovered surface. in new england the direction of these grooves is ordinarily a little east of south. upon the east coast of massachusetts and new hampshire the scratches trend much more to the east than they do over most of the interior. this is as it should be on the glacial theory, since the ice would naturally move outwards in the line of least resistance, which would, of course, be towards the open sea wherever that is near. in the interior of new england the scratches upon the rocks indicate a more southerly movement in the connecticut valley than upon the mountains in the western part of massachusetts. this also is as it should be upon the glacial theory. the scratches upon the mountains were made when the ice was at its greatest depth and when it moved over the country in comparative disregard of minor irregularities of surface, while in the valleys, at least in the later portion of the ice age, the movement would be obstructed except in one direction. in the interpretation of the glacial grooves and scratches it should be borne in mind that they often represent the work done during the closing stages of the period. just as the last shove of the carpenter's plane removes the marks of the previous work, so the last rasping of a glacial movement wears away the surfaces which have been previously polished and striated. in various places of new england it is interesting as well as instructive to trace the direction of the ice-movement by the distribution of boulders. my own attention was early attracted to numerous fragments of gneiss in eastern massachusetts containing beautiful crystals of feldspar, which proved to be peculiar to the region of lake winnepesaukee, a hundred miles to the north, and to a narrow belt stretching thence to the southwestward. in ascending almost any of the lower summits of the white mountains one's attention can scarcely fail of being directed to the difference between the material of which the mountains are composed and that of the numerous boulders which lie scattered over the surface. the local geologist readily recognises these boulders as pilgrims that have wandered far from their homes to the northward. trains of boulders, such as those already described in rhode island, can frequently be traced to some prominent outcrop of the rock in a hill or mountain-peak from which they have been derived. one of the earliest of these to attract attention occurs in the towns of richmond, lenox, and stockbridge, in the western part of massachusetts. here a belt of peculiar boulders about four hundred feet wide is found to originate in the town of lebanon, n. y., and to run continuously to the southeast for a distance of nine miles. west of fry's hill, where the outcrop occurs, no boulders of this variety of rock are to be found, while to the southeast the boulders gradually diminish in size as their distance from the outcrop increases. near the outcrop boulders of thirty feet in diameter occur, while nine miles away two feet is the largest diameter observed. sir charles lyell endeavoured to explain this train of boulders by the action of icebergs during a period of submergence--supposing that, as icebergs floated past or away from this hill in lebanon, n. y., they were the means of the regular distribution described. it is needless to repeat the difficulties arising in connection with such a theory, since now both by observation and experiment we have become more familiar with the movement of glacial ice. what we have already said about the transportation of boulders over switzerland by the alpine glaciers, and what is open to observation at the present time upon the large glaciers of alaska, closely agree with the facts concerning this richmond train of boulders, and we have no occasion to look further for a cause. indeed, trains of boulders ought to appear almost everywhere over the glaciated area; and so they do where all the circumstances are favourable. but, readily to identify the train, requires that to furnish the boulders there should be in the line of the ice-movement a projecting mass of rock hard enough to offer considerable resistance to the abrading agency of the ice and characteristic enough in its composition to be readily recognised. ship rock, in peabody, mass., weighing about eleven hundred tons, and mohegan rock, in montville, conn., weighing about ten thousand tons, have ordinarily been pointed to as boulders illustrating the power of ice-action. their glacial character, however, has been challenged from the fact that the variety of granite to which they belong occurs in the neighbourhood, and indeed constitutes the bed-rock upon which they rest.[av] some would therefore consider them, like some of which we have already spoken, to be boulders which have originated through the disintegration of great masses of rock, of which these were harder nuclei that have longer resisted the ravages of the tooth of time. it must be admitted that possibly this explanation is correct; but it is scarcely probable that, in a region where there are so many other evidences of glacial action, these boulders could have remained immovable in presence of the onward progress of the ice-current that certainly passed over them. [footnote av: popular science monthly, vol. xxxvii, pp. - .] however, as already seen, we are not left to doubt as to the movement of some boulders of great size. that which now claims the reputation of being the largest in new england is in madison, n. h., and measures thirty by forty by seventy-five feet. this can be traced to ledges of conway granite, about two miles away.[aw] many boulders in the vicinity of new haven, conn., can be identified, as from well-known trap-dykes, sixteen miles or more to the north. the so-called judge's cave, on west rock, feet above the adjoining valley and weighing a thousand tons, is one of these. professor edward orton[ax] describes a mass of clinton limestone near freeport, warren county, ohio, as covering an area of three-fourths of an acre, and as sixteen feet in thickness. it overlies glacial clays and gravels, and must have been transported bodily from the elevations containing this rock several miles to the northwest. [footnote aw: see w. . crosby's paper in appalachia, vol. vi, pp. - .] [footnote ax: geological survey of ohio, vol. iii, p. ,] [illustration: fig. .--mohegan rock.] portions of new england present the best illustrations anywhere afforded in america of what are called "drumlins." these are "lenticular-shaped" hills, composed of till, and containing, interspersed through their mass, numerous scratched stones of all sizes. they vary in length from a few hundred feet to a mile, and are usually from half to two-thirds as wide as they are long. in height they vary from twenty-five to two hundred feet. but, according to the description of mr. upham, whatever may be their size and height, they are singularly alike in outline and form, usually having steep sides, with gently sloping, rounded tops, and presenting a very smooth and regular contour. from this resemblance in shape to an elliptical convex lens, professor hitchcock has called them lenticular hills to distinguish these deposits of till from the broadly flattened or undulating sheets which are common throughout new england. [illustration: fig. .--drumlins in goffstown, n. h. (hitchcock).] the trend, or direction of the longer axis, of these lenticular hills is nearly the same for all of them comprised within any limited area, and is approximately like the course of the striæ or glacial furrows marked upon the neighbouring ledges. in eastern massachusetts and new hampshire, within twenty-five miles of the coast, it is quite uniformly to the southeast, or east-southeast. farther inland, in both of these states, it is generally from north to south, or a few degrees east of south; while in the valley of the connecticut river it is frequently a little to the west of south. in new hampshire, besides its accumulation in these hills, the till is frequently amassed in slopes of similar lenticular form. these have their position almost invariably upon either the south or north side of the ledgy hills against which they rest, showing a considerable deflection towards the southeast and northwest in the east part of the state. it cannot be doubted that the trend of the lenticular hills, and the direction taken by these slopes, have been determined by the glacial current, which produced the striæ with which they are parallel.[ay] [footnote ay: proceedings of the boston society of natural history, vol. xx, pp. , .] drumlins are abundant in the vicinity of boston, and constitute nearly all the islands in boston harbour. on the mainland, beacon hill, bunker hill, green hill, powderhorn hill, tufts college hill, winter hill, mount ida, corey hill, parker hill, wollaston heights, prospect hill, and telegraph hill are specimens. the northeastern corner of massachusetts and the southeastern corner of new hampshire are largely covered with these peculiar-shaped glacial deposits, while they are numerous as far west as fitchburg, in massachusetts, and ware, n. h., and in the northeastern part of connecticut. a little later, also, we shall refer to an interesting line of them in central new york. elsewhere in america, except in a portion of wisconsin, they rarely occur in such fine development as in new england. in europe they are best developed in portions of ireland. one's first impression in examining an exposed section of a drumlin would lead him to think that the mass was entirely unstratified; but closer examination shows that there is a coarse stratification, but evidently not produced by water-action. the accumulation has probably taken place gradually by successive deposits underneath the glacier itself. professor william m. davis has suggested a plausible explanation which we will briefly state. [illustration: fig. .--drumlins in the vicinity of boston (davis).] the frequency with which drumlins are found to rest upon a mass of projecting rock, the general co-ordination of the direction of their axes with the direction of the scratches upon the underlying rock, and the abundance of scratched stones in them, all support the theory that drumlins are formed underneath the ice-sheet, somewhat in the way that islands and bars of silt are formed in the delta of a great river. the movement of ice seems to have been concentrated in pretty definite lines, often determined by the contour of the bottom, leaving a slacker movement in intervening areas, which were evidently protected in some cases by projecting masses of rock. in these areas of slower movement there was naturally an accumulation at the same time that there was vigorous erosion in the lines of more rapid movement. there was doubtless a continual transfer of material from the end of the drumlin which abutted against the moving mass of ice to the lower end, as there is in the formation of an island in a river. if time enough had elapsed, the whole accumulation would have been levelled by the glacier and spread over the broader area where the more rapid lines of movement became confluent, and where the differential motion was less marked. drumlins are thus characteristic of areas in the glaciated region whose floor was originally only moderately irregular, and where there was an excessive amount of ground-moraine to be transported, and where the movement did not continue indefinitely. it has been suggested, also, that some of the long belts of territory in new england and central new york covered by drumlins may represent old terminal moraines which were subsequently surmounted by a readvance of the ice, and partially wrought over into their present shape. it is in new england, also, that kames are to be found in better development than anywhere else in america. these interesting remnants of the glacial age are clearly described by mr. james geikie. his account will serve as well for new england as for scotland. the sands and gravels have a tendency to shape themselves into mounds and winding ridges, which give a hummocky and rapidly undulating outline to the ground. indeed, so characteristic is this appearance, that by it alone we are often able to mark out the boundaries of the deposits with as much precision as we could were all the vegetation and soil stripped away and the various subsoils laid bare. occasionally, ridges may be tracked continuously for several miles, running like great artificial ramparts across the country. these vary in breadth and height, some of the more conspicuous ones being upward of four or five hundred feet broad at the base, and sloping upward at an angle of twenty-five or even thirty-five degrees, to a height of sixty feet and more above the general surface of the ground. it is most common, however, to find mounds and ridges confusedly intermingled, crossing and recrossing each other at all angles, so as to enclose deep hollows and pits between. seen from some dominant point, such an assemblage of kames, as they are called, looks like a tumbled sea--the ground now swelling into long undulations, now rising suddenly into beautiful peaks and cones, and anon curving up in sharp ridges that often wheel suddenly round so as to enclose a lakelet of bright clear water.[az] [footnote az: the great ice age, pp. , .] [illustration: fig. .--section of kame near dover, new hampshire. length, three hundred feet; height, forty feet; base, about forty feet above the cocheco river, or seventy-five feet above the sea. _a_, _a_, gray clay; _b_, fine sand; _c_, _c_, coarse gravel containing pebbles from six inches to one foot and a half in diameter; _d_, _d_, fine gravel (upham).] [illustration: fig. .--kames in andover mass.] in new england attention was first directed to kames in , by president edward hitchcock, in a paper before the american association of geologists and naturalists, describing the gravel ridges in andover, mass. in the accompanying plate is shown a portion of this kame system, which has a double interest to me from the fact that it was while living upon the banks of the shawshin river, near where the kames and the river intersect, that i began, in , my special study of glacial deposits. the andover ridges are composed of imperfectly stratified water-worn material, and are very sharply defined, from the town of chelsea, back from the coast into new hampshire, for a distance of twenty-five miles. the base of the ridges does not maintain a uniform level, but the system descends into shallow valleys, and rises over elevations of one hundred to two hundred feet, without interruption. this indifference to slight changes of level is specially noticeable where the system crosses the merrimac river, just above the city of lawrence. it is also represented in the accompanying plate, where the base of the ridges in the immediate valley of the shawshin is fifty feet lower than the base of those a short distance to the north, at the points marked _a_, _b_, and _c_. the ridges here terminate at the surface in a sharp angle, and are above their base forty-one feet at _a_, forty-nine feet at _b_, and ninety-one feet at _c_. between _c_ and _b_ there is an extensive peat-swamp, filling the depression up to the level of an outlet through which the surplus water has found a passage. [illustration: fig. .--longitudinal kames near hingham, massachusetts. the parallel ridges of gravel in the foreground run nearly east and west, and coalesce at each end, near the edges of the picture, to form an elongated kettle-hole. the ridges from fifty to sixty feet in height. the kame-stream was here evidently emptying into the ocean a few miles to the east (bouvé).] several systems of kames approximately parallel to this have been traced out in massachusetts and new hampshire, while the remnants of a very extensive system are found in the connecticut valley above the massachusetts line. but they abound in greatest profusion in the state of maine, where professor george h. stone has plotted them with much care. the accompanying map gives only an imperfect representation of the ramifying systems which he has traced out, and of the extent to which they are independent of the present river-channels. one of the longest of these extends more than one hundred miles, crossing the penobscot river nearly opposite grand lake, and terminating in an extensive delta of gravel and sand in cherryfield, nearly north of mount desert. this is represented on our map by the shaded portion west of the machias river. locally these ridges are variously designated as "horsebacks," "hogbacks," or "whalebacks," but that in andover, mass., was for some reason called "indian ridge." nowhere else in the world are these ridges better developed than in new england, except it be in southern sweden, where they have long been known and carefully mapped. [illustration: fig. .--the kames of maine and southeastern new hampshire. (stone.)] the investigations of mr. w. . crosby upon the composition of till in eastern massachusetts is sufficiently important in its bearings upon the question of glacial erosion to merit notice at this point.[ba] the object of his investigations was to determine how much of the so-called ground moraine, or till, consisted of material disintegrated by mechanical action, and how much by chemical action. the "residuary clay," which has arisen from chemical decomposition, would properly be attributed to the disintegrating agencies of preglacial times, while the clay, which is strictly mechanical in its origin, remains to represent the true "grist" or "rock flour" of the glacial period. [footnote ba: proceedings of the boston society of natural history, vol. xxv ( ), pp. - .] the results of mr. crosby's investigations show that "not more than one-third of the _detritus_ composing the till of the boston basin was in existence before the ice age, and that the remaining two-thirds must be attributed to the mechanical action of the ice-sheet and its accompanying torrents of water. in other words, if we assume the average thickness of the drift as thirty feet, the amount of glacial erosion can scarcely fall below twenty feet. after scraping away the residuary clays and half-decomposed material, the ice-sheet has cut more than an equal depth into the solid rocks." mr. crosby's investigations also convinced him that the movement of the till, or ground moraine, underneath the ice was not _en masse_, but that "it must have experienced differential horizontal movements or flowing, in which, normally, every particle or fragment slipped or was squeezed forward with reference to those immediately below it, the velocity diminishing downward through the friction of the underlying ledges.... the glaciation was not limited to masses which were firmly caught between the ice and the solid ledges, and it was in every case essentially a slipping and not a rolling movement.... these differential horizontal movements mean that the till acted as a lubricant for the ice-sheet; and the clayey element, especially, co-operating in many cases with the pent-up subglacial waters, must have greatly facilitated the onward progress of the ice." he concludes, therefore, that the onward movement of the vast ice-sheet greatly exceeded that of the main part of the ground moraine, the ice-sheet slipping over the till, the whole being in some degree analogous to that of a great land-slip. "in both cases the progress of a somewhat yielding and mobile mass is facilitated by an underlying clayey layer saturated with water." _new york, new jersey, and pennsylvania._ west of new england the glacial phenomena over the northern part of the united states are equally marked all the way to the missouri river, and the boundary-line of the glaciated region can be traced with little difficulty. it emerges from new york bay on staten island and enters new jersey at perth amboy. a well-formed moraine covers the northern part of staten island, and upon the mainland marks the boundary from perth amboy, around through raritan, plainfield, chatham, morris, and hanover, to rockaway, and thence in a southwesterly direction to belvidere, on the delaware river. that portion of new jersey lying north of this serpentine line of moraine hills is characterised by the presence of transported boulders, by numerous lakes of evident glacial origin, and by every other sign of glacial action, while south of it all these peculiar characteristics are absent. the observant passenger upon the railroad trains between new york and philadelphia can easily recognise the moraine as it is passed through on the pennsylvania railroad at metuchen and on the bound brook railroad at plainfield. near drakestown, in morris county, there is a mass of blue limestone measuring, as exposed, thirty-six by thirty feet, and which was quarried for years before discovering that it was a boulder brought with other drift material from many miles to the northwest and lodged here a thousand feet above the sea. across pennsylvania the glacial boundary passes through northampton, monroe, luzerne, columbia, sullivan, lycoming, tioga, and potter counties, where it enters the state of new york, running still in a northwest direction through allegany and cattaraugus counties to the vicinity of salamanca. here it turns to the south nearly at a right angle, running southwestward to chautauqua county and re-entering pennsylvania in warren county, and thence passing onward in the same general direction through crawford, venango, mercer, butler, and lawrence counties to the ohio line in columbiana county, about ten miles north of the ohio river. the occurrence of a well-defined terminal moraine to mark the glacial boundary eastward from pennsylvania led professor lewis and myself, who made the survey of that state in , to be rather too sanguine in our expectations of finding an equally well-marked moraine everywhere along the southern margin of the glaciated area; still, the results are even more interesting than would have been the exact fulfilment of our expectations, since they more fully revealed to us the great complexity of effect which is capable of being brought about by ice-action. before proceeding farther with the details, therefore, it will be profitable at this point to pause in the narrative and briefly record a few generalisations that have forced themselves into prominence during the years in which field-work has been in progress. previous to our explorations in pennsylvania it had been thought that the indications of ice-action would extend much farther south in the valleys than on the mountains, and this indeed would have been the case if the glaciers in northern pennsylvania had been of local origin; but our experience very soon demonstrated that the great gathering-place of the snows which produced the glacial movement in northern pennsylvania could not have been local, but that over the northern part of that state there was distinct evidence of a continental movement of ice whose centre was far beyond the alleghanies. for example, we found that the evidences of direct glacial action extended farther south upon the hills and plateaus than they did in the narrow valleys, while everywhere on the very southern border of glacial indications we found boulders that had been brought from the granitic region of northern new york or central canada. in eastern pennsylvania we found indeed a terminal moraine more or less distinctly marking the southern border over the highlands. this was more specially true in northampton and monroe counties. in northampton county it was very interesting to see long lines of hills, a hundred or more feet in height and lying several hundred feet above the delaware river, composed entirely of glacial _débris_, much of which had been brought bodily over the sharp summit of the blue ridge, or kittatinny mountain, which rises as a continuous wall to the northwest and is everywhere several hundred feet higher than the moraine in northampton county. the summit of blue ridge, also, as far south as the glacial movement extended, shows evident signs of glacial abrasion, some hundreds of feet evidently having been removed by that means, leaving a well-defined shoulder, marking the limits of its southwestern border. resting upon the summit of the glaciated portion of the blue ridge, there are also numerous boulders of helderberg limestone, which must have been brought from ledges at least five hundred feet lower than the places upon which they now lie. in monroe county the terminal moraine marking there the extreme limit of the ice-movement is upon an extensive plateau of pocono sandstone, about eighteen hundred feet above sea-level, and five or six hundred feet lower than the crest of the alleghany mountains, a short distance to the north. the moraine hills are here well marked by the occurrence of circular lakelets and kettle-holes (such as have been described as characteristic of the shores and islands bordering the south of new england); by the occurrence of granitic boulders, which must have been brought from the adirondacks or canada; and by the various other indications referred to on a previous page. as already intimated, the instructive point in our observations is the fact that, between kittatinny mountain, in northampton county, and pocono plateau, in monroe county, there is a longitudinal depression, running northeast by southwest, parallel with the ranges of the mountain system, which is here about a thousand feet below the respective ridges on either side. this, therefore, is one of the places where we should have expected a considerable southern extension of the ice, if it had been largely due to local causes. now, while there is indeed a gradual southern trend down the flanks of the mountain, yet, upon reaching the axis of the valley, there appears at once a very marked change in the character of the deposit, and the influence of powerful streams of water becomes manifest, and it is evident, upon a slight inspection, that we have come upon a line of drainage which sustained a peculiar relation to the continental ice-sheet. from stroudsburg, near the delaware water-gap, to weissport, on the lehigh river, a distance of about thirty miles, the valley between the mountains is continuous, and the elevation at each end very nearly the same. but about half-way between the two places, near saylorsburg, there is a river-parting from which the water now runs on the one hand north to stroudsburg, and thence to the delaware river, and on the other hand south, through big and aquonchichola creeks, to the lehigh river. the river-parting is formed by a great accumulation of gravel, whose summit is about two hundred feet above the level of the valleys into which the creeks empty at either end; and there are numerous kettle-holes and lakelets in the vicinity, such as characterize the glacial region in general. in short, we are, without doubt, here on a well-marked terminal moraine much modified by strong water-action in a valley of glacial drainage. the gravel and boulders are all well water-worn, and the material is of various kinds, including granite boulders from the far north, such as characterise the terminal moraine on the highlands; but the pebbles are not scratched, and the gravel is more or less stratified. it is evident that we are here where a violent stream of water poured forth from that portion of the ice-front which filled this valley, and which found its only outlet in the direction of the lehigh river. the gravel can be traced in diminishing quantities to the southward, in accordance with this theory, while to the northward there extends a series of gravel ridges, or kames, such as we have shown naturally to owe their origin to the accumulations taking place in ice-channels formed near the front of a glacier as it slowly melts away. from similar occurrences of vast gravel accumulations in other valleys stretching southward from the glacial margin, we came to expect that, wherever there was an open, line of drainage from the glaciated region southward, the point of intersection between the glacial margin and the drainage valley would be marked by an excessive accumulation of water-worn gravel, diminishing in coarseness and abundance down the valleys in proportion to the distance from the glacial margin. for example, the delaware river emerges from the glaciated region at belvidere, and there are there vast accumulations of gravel rising a hundred or more feet above the present level of the river, while gravel terraces, diminishing in height, mark the river below to tide-water at trenton. the lehigh river leaves the glaciated region at hickory run, a few miles above mauch chunk, but the gorge is so steep that there was little opportunity either for the accumulation of gravel there or for its preservation. still, the transported gravel and boulders characteristic of the melting floods pouring forth from a glacier, are found lining the banks of the lehigh all along the lower portion of its course. in the susquehanna river we have a better example at beach haven, in luzerne county, where there are very extensive accumulations of gravel resting on the true glacial deposits of the valley, and extending down the river in terraces of regularly diminishing height for many miles, and merging into terraces of moderate elevation which line the susquehanna valley throughout the rest of its course. above beach haven the gravel deposits in the trough of the river valley are more irregular, and betray the modifying influence of the slowly decaying masses of ice which belonged to the enveloping continental glacier. westward from the north fork of the susquehanna, similar extensive accumulations of gravel occur at the intersection of fishing creek in columbia county, muncy, loyalsock, lycoming, and pine creeks in lycoming county, all tributary to the susquehanna river, and all evidently being channels through which the melting floods of the ice-sheet brought vast quantities of gravel down to the main stream. williamsport, on the west branch of the susquehanna, is built upon an extensive terrace containing much granitic material, brought down from the glaciated region by lycoming creek, when it was flooded with the waters melted from the continental ice-sheet which had here surmounted the alleghanies and invaded the valley of the susquehanna. analogous deposits of unusual amounts of gravel, occurring in streams flowing southward from the glaciated region, occur at great valley, little valley, and steamburg in cattaraugus county, new york, and at russelburg and garland in warren county, pennsylvania, also at titusville and franklin in venango county, and at wampum in lawrence county, of the same state. as a rule, professor lewis and myself found it more difficult to determine with accuracy the exact point to which the ice extended in the axis of these south-flowing valleys than we did upon the highlands upon either side; and, in looking for the positive indications of direct ice-action in these lines of drainage, we were almost always led up the valley to a considerable distance inside of the line. this arose from our inexperience in interpreting the phenomena, or rather from our inattention to the well-known determining facts in the problem. on further reflection it readily appeared that this was as it should be. the ice-front, instead of extending farther down in a narrow valley than on the adjoining highlands (where they are of only moderate elevation) ought not to extend so far, for the subglacial streams would not only wear away the ice of themselves, but would admit the air into the tunnels formed by them so as to melt the masses both from below and from above, and thus cause a recession of the front. if we had understood this principle at the beginning of our survey, it would have saved us much perplexity and trouble. a single further illustration of this point will help to an understanding of many references which will hereafter be made to the water deposits which accumulated in the lines of drainage running southward from the glaciated area. at warren, pa., conewango creek, which is the outlet from chautauqua lake, enters the alleghany river after flowing for a number of miles in a deep valley with moderate slopes. in ascending the creek from warren, the gravel terraces, which rise twenty-five or thirty feet above high-water mark, rapidly increase in breadth and height, and the pebbles become more and more coarse. after a certain distance the regular terraces begin to give place to irregular accumulations of gravel in ridges and knobs. in the lower portion of the valley no pebbles could be found which were scratched. up the valley a few miles pebbles were occasionally discovered which showed some slight indications of having been scratched, but which had been subjected to such an amount of abrasion by water-action as almost to erase the scratches. on reaching ackley's station, the stream is found to be cutting through a regular terminal moraine, extending across the valley and full of clearly marked glaciated stones. above this terminal moraine the terraces and gravel ridges which had characterised the valley below disappear, giving place to long stretches of level and swampy land, which had been subject to overflow. something similar to this so often appears, that there can be no question as to its meaning, which is, that during the farthest extent of the ice the front rested for a considerable period of time along the line marked by the terminal moraine. during this period there occurred both the accumulation of the moraine and of the gravel terraces in the valley below, due to the vast flow of water emerging from the ice-front, especially during the period when it was most rapidly melting away. upon the retreat of the ice, the moraine constituted a dam which has not yet been wholly worn away. for a while the water was so effectually ponded back by this as to form a lake, which has since become filled up with sediment and accumulations of peat. from this it is evident, also, that when the ice began to retreat, the retreat was so continuous and rapid that no parallel terminal moraines were formed for many miles. before leaving this section we will summarise the leading facts concerning the glacial phenomena north of pennsylvania and new jersey. from the observations of professor smock, it appears that, from the southern margin the ascent to the summit of the ice-sheet was pretty rapid; the depth one mile back from the margin being not much less than a thousand feet. "northward the angle of the slope diminished, and the glacier surface approximated to a great level plain. the distance between the high southwestern peaks of the catskills and pocono knob in pennsylvania is sixty miles. the difference in the elevation of the glacier could not have exceeded a thousand feet,"[bb] that is, the slope of the surface was about seventeen feet to the mile. [footnote bb: american journal of science, vol. cxxv, , p. _et seq._] professor dana estimates the thickness of the ice in southern connecticut to have been between fifteen hundred and two thousand feet. attempts to calculate the thickness of the ice farther north, except from actual discovery of glacial action on the summits of the mountains, are based upon uncertain data with reference to the slope necessary to secure glacial movement. in the alps the lowest mean slopes down which glaciers move are about two hundred and fifty feet to a mile; but in greenland, jensen found the slope of the frederickshaab glacier to be only seventy-five feet to the mile, while helland found that of the jakobshavn glacier to be only forty-five feet. it is doubtful if even that amount is necessary to secure a continental movement of ice, since, as already remarked, it is unsafe to draw inferences concerning the movements of large masses of ice from those of smaller masses in more constricted areas. we have seen, from the glacial deposits on the top of mount washington, that over the northern part of new england the ice was more than a mile in depth. we have no direct evidence of the depth of the stream which surrounded the adirondack mountains. nor, on the other hand, are we certain that the catskills were not completely enveloped in ice, though most observers, reasoning from negative evidence, have supposed that to be the case. but from the facts stated concerning the boulders along the glacial boundary in pennsylvania, it is certain that the ice was deep enough to surmount the ridge of the alleghanies where they are two thousand and more feet in height. at the least calculation the ice must have been five hundred feet thick, in order to secure the movement of which there is evidence across the appalachian range. supposing this to be the height of the ice above the sea on the crest of the alleghanies, and that the slope of the surface of the ice-sheet was as moderate as professor smock has estimated it (namely seventeen feet to the mile), the ice would be upwards of six thousand feet in thickness in the latitude of the adirondacks, which corresponds closely with the positive evidence ave have from the mountains in new england. a study of the map of new york will make it easy to understand the distribution of some interesting glacial marks over the state. the distance along the hudson from the glacial boundary in the vicinity of new york to the valley of the mohawk is about one hundred and sixty miles. prom the glacial boundary at salamanca, n. y., to the same valley, is not over eighty miles. it is easy to see, therefore, that when, in advancing, the ice moved southward past the adirondacks, the east end of the valley of the mohawk was reached and closed by the ice, while at the west end of lake ontario the ice-front was still in canada. thus the drainage, which naturally followed the course of the st. lawrence, would first be turned through the mohawk. afterwards, when the mohawk had been closed by ice, the vast amount of ponded water was compelled to seek a temporary outlet over the lower passages leading into the susquehanna or into the alleghany. a number of such passages exist. one can be traced along the line of the old canal from utica to binghamton, whose highest level is not far from eleven hundred feet. another lies in a valley leading south of cayuga lake, whose highest point, at wilseyville, is nine hundred and forty feet above tide. another leads south to the chemung river from seneca lake, whose highest point, at horseheads, is less than nine hundred feet above tide. the cols farther west are somewhat more elevated; the one at portage, leading from the genesee river into the canisteo, being upwards of thirteen hundred feet, and that of dayton, leading from cattaraugus creek into the conewango, being about the same. of other southern outlets farther west we will speak later on. fixing our minds now upon the region under consideration, in the southern part of the state of new york, we can readily see that a glacial lake must have existed in front of the ice while it was advancing, until it had reached the river-partings between the mohawk and the st. lawrence rivers on the north and the susquehanna and alleghany rivers on the south. after the ice had attained its maximum extension, and was in process of retreat, there would be a repetition of the phenomena, only they would occur in the reverse order. the glacial markings which we see are, of course, mainly those produced during the general retreat of the ice. the susquehanna river stretching out its arms--the chenango and chemung rivers--to the east and the west, evidently serves as a line of drainage for the vast glacial floods. these floods have left, along their courses, extensive elevated gravel terraces, with much material in them which is not local, but which has been washed out of the direct glacial deposits from the far north. the east-and-west line of the water-parting throughout the state is characterised by excessive accumulations of glaciated material, forming something like a terminal moraine, and is designated by president chamberlin as "the terminal moraine of the second glacial epoch," corresponding, as he thinks, to the interior line already described as characterising the south shore of new england. in the central part of new york the remarkable series of "finger lakes," tributary to lake ontario and emptying into it through the oswego and genesee rivers, all have a glacial origin. probably, however, they are not due in any great degree to glacial erosion, but they seem to occupy north-and-south valleys which had been largely formed by streams running towards the st. lawrence when there was, by some means (probably through the mohawk river), a much deeper outlet than now exists, but which has been filled up and obliterated by glacial _débris_. the ice-movement naturally centred itself more or less in these north-and-south valleys, and hence somewhat enlarged them, but probably did not deepen them. the ice, however, did prevent them from becoming filled with sediment, and on its final retreat gave place to water. between these lakes and lake ontario, also, and extending east and west nearly all the way from syracuse to rochester, there is a remarkable series of hills, from one hundred to two or three hundred feet in height, composed of glacial _débris_. but while the range extends east and west, the axis of the individual hills lies nearly north and south. these are probably remnants of a morainic accumulation which were made during a pause in the first advance of the ice, and were finally sculptured into their present shape by the onward movement of the ice. these are really "drumlins," similar to those already described in northeastern massachusetts and southeastern new hampshire. in the valley of central new york these have determined the lines of drainage of the "finger lakes," and formed dams across the natural outlets of nearly all of them. north of the state of new york the innumerable lakes in canada are all of glacial origin, being mostly due to depressions of the nature of kettle-holes, or to the damming up of old outlets by glacial deposits. a pretty well-marked line of moraine hills, formed probably as terminal deposits in the later stages of the ice age, runs from near the eastern end of lake ontario to the georgian bay, passing south of lake simcoe. _the mississippi basin._ the physical geography of the glaciated region north of the ohio river is so much simpler than that of new england and the middle states, that its characteristics can be briefly stated. ohio, indiana, and illinois are covered with nearly parallel strata of rock mostly of the carboniferous age. in general, the surface slopes gently to the west; the average elevation of ohio being about a thousand feet above tide, while that of the great lakes to the north and of the middle portion of the mississippi valley is less than six hundred feet. the glacial deposits are spread in a pretty even sheet over the area which was reached by the ice in these states, and the lines of moraine, of which a dozen or more have been partially traced in receding order, are much less clearly marked than they are in new england, or in michigan, and the states farther to the northwest. the line marking the southern limit attained by the ice of the glacial period in these three states is as follows: entering ohio in columbiana county, about ten miles north of the ohio river, the glacial boundary runs westward through new lisbon to canton in stark county, and thence to millersburg in holmes county. a few miles west of this place it turns abruptly south, passing through danville in knox county, newark in licking county, lancaster in fairfield county, to adelphi in ross county. thence bearing more westward it passes through chillicothe to southeastern highland county and northwestern adams, reaching the ohio river near ripley, in clermont county. thence, following the north bank of the ohio river to cincinnati, it crosses the river, and after extending through the northern part of boone county, kentucky, and recrossing the river to indiana, not far from rising sun, it again follows approximately the north bank of the river to within about ten miles of louisville, ky., where it bends northward running through clarke, scott, jackson, bartholomew, and brown counties to martinsville, in morgan county, where it turns again west and south and follows approximately the west branch of the white river through owen, greene, and knox counties, where it crosses the main stream of white river, and, continuing through gibson and posey counties, crosses the wabash river near new harmony. in illinois the line still continues southwesterly through white, gallatin, saline, and williamson counties, where it reaches its southern limit near carbondale, in latitude ° ', and from this point trends northwestward, approximately following the northeastern bluff of the mississippi river, to the vicinity of carondelet, mo., a short distance south of st. louis. beyond the mississippi the line follows approximately the course of the missouri river across missouri, and continues westward to the vicinity of manhattan, in kansas, where it turns northward, keeping about a hundred miles west of the missouri river, through eastern kansas and nebraska, and striking the river near the mouth of the niobrara, in south dakota. from there the line follows approximately the course of the missouri river to the vicinity of fort benton, in northwestern montana, where the line again bears more northward, running into british america. it is still in dispute whether the ice extended from the eastern centre far enough west to join the ice-movement from the rocky mountain plateau. dr. george m. dawson[bc] is of the opinion that it did not, but that there was a belt of a hundred miles or more, east of the rocky mountains, which was never covered by true glacial ice. mr. upham[bd] is equally confident that the two ice-movements became confluent, and united upon the western plateau of manitoba. the opportunity for such a difference of opinion arises in the difficulty sometimes encountered of distinguishing between a direct glacial deposit and a deposit taking place in water containing boulder-laden icebergs. where mr. upham supposes the ice-fields of the east and of the west to have been confluent in western manitoba, dr. dawson supposes there was an extensive subsidence of the land sufficient to admit the waters of the ocean. leaving this question for the present undetermined, we will now rapidly summarise the glacial phenomena west of the third meridian from washington (which corresponds nearly with the western boundary of pennsylvania), and east of the rocky mountains. [footnote bc: transactions of the royal society of canada, vol. viii, sec. iv, pp. - .] [footnote bd: american geologist, vol. vi, september, ; bulletin of the geological society of america, vol. ii, pp. - .] that the glacial movement extended to the southern boundary just delineated is established by the presence down to that line of all the signs of glacial action, and their absence beyond. glacial groovings are found upon the freshly uncovered rock surfaces at frequent intervals in close proximity to the line all along its course, while granitic boulders from the far north are scattered, with more or less regularity, over the whole intervening space between this line and the canadian highlands. i have already referred to a boulder of jasper conglomerate found in boone county, kentucky, which must have come from unique outcroppings of this rock north of lake huron. granitic boulders from the lake superior region are also found in great abundance at the extreme margin mentioned in southern illinois. west of the missouri river it is somewhat more difficult to delineate the boundary with accuracy, on account of an enveloping deposit of fine loam, technically called "loess." loess is very abundant in the whole valley of the missouri river below yankton, south dakota, being for a long distance in the vicinity of the river a hundred feet or more in depth. over northern missouri and southern illinois the deposit is nearly continuous, but less in depth, and everywhere in that region tends to hide from view the unstratified glacial deposit continuously underlying it. a single instance of personal experience will illustrate the condition of things. while going south from chicago, in search of the southern limit of glacial action, i stopped off from the train at du quoin, about forty miles north of where i subsequently found the boundary. here the whole surface was covered with loess, two or three feet in depth. below this was a gravelly soil, three or four feet in thickness, which contained many scratched pebbles of granite. a well which had recently been dug, reached the rock at a depth of twenty feet, and revealed a beautifully polished and scratched surface, betraying, beyond question, the action of glacial ice. as we shall show a little later, it is probable that, about the time the ice of the glacial period had reached its maximum development, this area, which is covered with loess, was depressed in level, and remained under water during a considerable portion of the period when the ice-front was retreating. [illustration: fig. .--western face of the kettle-moraine, near eagle, waukesha county, wisconsin. (from a photograph by president t. c. chamberlain, united states geological survey.)] to such an extent is this portion of the area included in southern iowa, northern missouri, southern illinois, and the extreme southern portions of indiana and ohio covered with loess, that it has been difficult to determine the relation of its underlying glacial deposits to the more irregular deposits found farther north. at an early period of recent investigations, while making a geological survey of the state of wisconsin, president t. c. chamberlin fixed upon the line of moraine hills, which can be seen upon our map, running southward between green bay and lake michigan, and sweeping around in a curve to the right, passing south of madison and northward along the line of wisconsin river, and in another curve to the left, around the southern end of lake michigan, as the "terminal moraine of the second glacial epoch." in wisconsin the character of this line of moraine hills had been discovered and described by colonel charles whittlesey, in . it was first named the "kettle-moraine," because of the frequent occurrence in it of "kettle-holes." this line of moraine hills has been traced with a great degree of confidence across the entire glaciated area, as shown upon our map, but it is not everywhere equally distinct, and, as will be observed, follows a very irregular course. beginning in ohio we find it coinciding nearly with the extreme glacial boundary until it reaches the valley of the scioto river, on the sixth meridian west from washington, where it begins to bear northward and continues in that direction for a distance of sixty or seventy miles, and then turns southward again in the valley of the miami, having formed between these two valleys a sort of medial moraine.[be] a similar medial moraine had also been noted by president chamberlin between the valleys of the grand and cuyahoga rivers, in the eastern part of ohio. indeed, for the whole distance across ohio and indiana, this moraine occurs in a series of loops pointing to the south, corresponding in general to the five gentle valleys which mark the territory, namely, those of the grand and mahoning rivers; the sandusky and scioto rivers; the great miami river; the white river; and the maumee and wabash rivers. everywhere, however, over this area these morainic accumulations approximate pretty closely to the extreme boundary of the glaciated region. [footnote be: see map at the beginning of the chapter.] in illinois president chamberlin's original determination of the moraine fixed it near the southern end of lake michigan, as shown upon our map, but mr. frank leverett has subsequently demonstrated that there is a concentric series of moraines south of this, reaching across the state, (but somewhat obscured by superficial accumulations of loess referred to) and extending nearly to the latitude of st. louis. west of wisconsin president chamberlin's "terminal moraine of the second glacial epoch" bends southward through eastern minnesota, and, sweeping down through central iowa, forms, near the middle of the northern part of that state, a loop, having its southern extremity in the vicinity of des moines. the western arm of this loop runs through minnesota in a northwesterly direction nearly parallel with the upper portion of the valley of the minnesota, until reaching the latitude of the head-waters of that river, where, in the vicinity of the sisseton agency, in dakota, it turns to the south by an acute angle, and makes a loop in that state, extending to the vicinity of yankton, and with the valley of the james river as its axis. the western arm of this loop follows pretty closely the line of the eastern edge of the trough of the missouri river, constituting what is called the "missouri coteau," which continues on as a well-marked line of hills running in a northwesterly direction far up into the dominion of canada. one of the most puzzling glacial phenomena in the mississippi valley is the driftless area which occupies the southeastern portion of minnesota, the southwestern part of wisconsin, and the northwestern corner of iowa, as delineated upon our map. this is an area which, while being surrounded on every side by all the characteristic marks of glaciation, is itself conspicuous for their entire absence. its rocks preserve no glacial scratches and are covered by no deposits of till, while northern boulders avoided it in their journey to more southern latitudes. the reason for all this is not evident in the topography of the region. the land is not higher than that to the north of it, nor is there any manifest protection to it by the highlands south of lake superior. nor yet is there any reason to suppose that any extensive changes of level in former times seriously affected its relations to the surrounding country. professor dana, however, has called attention to the fact that even now it is in a region of comparatively light precipitation, suggesting that the snow-fall over it may always have been insignificant in amount. but this could scarcely account for the failure of the great ice-wave of the north to overrun it. we are indebted again to the sagacity of president chamberlin in suggesting the true explanation. by referring to the map it will be noticed that this area sustains a peculiar relation to the troughs of lake michigan and lake superior, while from the arrangements of the moraines in front of these lakes it will be seen that these lake basins were prominent factors in determining the direction of the movement of the surplus ice from the north. it is the more natural that they should do so because of their great depth, their bottoms being in both cases several hundred feet below the present water-level, reaching even below the level of the sea. these broad, deep channels seem to have furnished the readiest outlet for the surplus ice of the north, and so to have carried both currents of ice beyond this driftless area before they became again confluent. the slight elevation south of lake superior served to protect the area on account of the feebleness of direct movement made possible by the strength of these diverging lateral ice-currents. the phenomenon is almost exactly what occurs where a slight obstruction in a river causes an eddy and preserves a low portion of land below it from submergence. a glance at the map will make it easily credible that an ice-movement south of manitoba, becoming confluent with one from lake superior, pushed far down into the missouri valley and spread eastward to the mississippi river, south of the unglaciated driftless area, and there became confluent with a similar movement which had been directed by the valleys of lake michigan and lake erie. there can be little doubt that president chamberlin's explanation is in the main correct, and we have in this another illustration of the analogy between the behaviour of moving ice and that of moving water. [illustration: fig. .--section of the east-and-west glacial furrows, on kelly's island, preserved by mr. younglove. fine sediment rests immediately on the rock, with washed pebbles at the surface.] the accompanying illustrations will give a better idea than words can do of the celebrated glacial grooves on the hard limestone islands near sandusky, in the western part of lake erie. through the interest aroused in them by an excursion of the american association for the advancement of science, while meeting in cleveland, ohio, in , the kelly island lime and transport company, of which mr. m. c. younglove is the president, has been induced to deed to the western reserve historical society for preservation a portion of one of the most remarkable of the grooves still remaining. the portion of the groove preserved is thirty-three feet across, and the depth of the cut in the rock is seventeen feet below the line, extending from rim to rim. originally there was probably here a small depression formed by preglacial water erosion, into which the ice crowded the material, which became its graving-tool, and so the rasping and polishing went on in increasing degree until this enormous furrow is the result. the groove, however, is by no means simple, but presents a series of corrugations merging into each other by beautiful curves. when exposed for a considerable length it will resemble nothing else so much as a collection of prostrate corinthian columns lying side by side on a concave surface. the direction of these grooves is a little south of west, corresponding to that of the axis of the lake. this is nearly at right angles to the course of the ice-scratches on the summit of the water-shed south of this, between the lake and the ohio river. the reason for this change of direction can readily be seen by a little attention to the physical geography. the highlands to the south of the lake rise about seven hundred feet above it. when the ice period was at its climax and overran these highlands, the ice took its natural course at right angles to the terminal moraine and flowed southeast according to the direction indicated by the scratches on the summit; but when the supply of ice was not sufficient to overrun the highlands, the obstruction in front turned the course and the resultant was a motion towards toledo and the maumee valley, where in the vicinity of fort wayne an extensive terminal moraine was formed. [illustration: fig. .--same as the preceding. (courtesy of m. c. younglove.)] the much-mooted question of a succession of glacial epochs finds the most of its supporting facts in the portion of the glaciated area lying west of pennsylvania. that there have been frequent oscillations of the glacial front over this area is certain. but it is a question whether the glacial deposits south of this distinct line of moraine hills are so different from those to the north of it as to necessitate the supposition of two entirely distinct glacial epochs. this can be considered most profitably here. the following are among the points with reference to which the phenomena south of the moraine just delineated differ from those north of the line: . the glacial deposits to the south appear to be distributed more uniformly than those to the north. to the north the drift is often accumulated in hills, and is dotted over with kettle-holes, while to the south these are pretty generally absent. any one travelling upon a line of railroad which traverses these two portions of the glaciated area as indicated upon our map can easily verify these statements. . the amount of glacial erosion seems to be much less south of the line of moraine hills delineated than north of them. still, glacial striæ are found, almost everywhere, close down to the extreme margin of the glaciated area. . the gravel deposits connected with the drainage of the glacial period are much less abundant south of the so-called "terminal moraine of the second glacial period" than they are north of it. south of this moraine the water deposits attributed to the glacial period are of such fine silt as to indicate slow-moving currents over a gentle low slope of the surface. . the glacial deposits to the south are more deeply coloured than those to the north, showing that they have been longer exposed to oxidising agencies. even the granitic boulders show the marks of greater age south of this line, being disintegrated to a greater extent than those to the north. . and, finally, there occur, over a wide belt bordering the so-called moraine hills of the second glacial epoch, extensive intercalated beds of vegetal deposits. among the earliest of these to be discovered were those of montgomery county, ohio, where, in , professor orton, of the ohio survey, found at germantown a deposit of peat fourteen feet thick underneath ninety-five feet of till, and there seem also to be glacial deposits underneath the peat as well as over it. the upper portion of the peat contains "much undecomposed sphagnous mosses, grasses, and sedges, and both the peat and the clayey till above it" contain many fragments of coniferous wood which can be identified as red cedar (_juniperus virginianus_). in numerous other places in that portion of ohio fresh-appearing logs, branches, and twigs of wood are found underneath the till, or mingled with it, much as boulders are. near darrtown, in butler county, ohio, red cedar logs were found under a covering of sixty-five feet of till, and so fresh that the perfume of the wood is apparently as strong as ever. similar facts occur in several other counties in the glaciated area of southern ohio and southern indiana. professor collett reports that all over southwestern indiana peat, muck, rotted stumps, branches, and leaves of trees are found from sixty to one hundred and twenty feet below the surface, and that these accumulations sometimes occur to a thickness of from two to twenty feet. [illustration: fig. .--section of till near germantown, ohio, overlying thick bed of peat. the man in the picture stands upon a shelf of peat from which the till has been eroded by the stream. the dark spot at the right hand of the picture, just above the water, is an exposure of the peat. the thickness of the till is ninety-five feet. the partial stratification spoken of in the text can be seen about the middle of the picture. the furrows up and down had been made by recent rains. (united states geological survey.) (wright.)] farther to the northwest similar phenomena occur. professor n. h. winchell has described them most particularly in fillmore and mower counties, minnesota, from which they extend through a considerable portion of iowa. in the above counties of minnesota a stratum of peat from eighteen inches to six or eight feet in thickness, with much wood, is pretty uniformly encountered in digging wells, the depth varying from twenty to fifty feet. this county is near the highest divide in the state of minnesota, and from it "flow the sources of the streams to the north, south, and east." the wood encountered in this stratum indicates the prevalence f coniferous trees, and the peat mosses indicate a cool and moist climate. nor are intercalated vegetable deposits absent from the vast region farther north over the area that drains into hudson bay. at barnesville, in clay county, minnesota, which lies in the valley of the red river of the north, and also in wilkin county in the same valley, tamarack wood and sandy black mud containing many snail-shells have been found from eight to twelve feet below a surface of till; and dr. robert bell reports the occurrence of limited deposits of lignite between layers of till, far to the northwest, in canada, and even upon the southern part of hudson bay; while mr. j. b. tyrrell reports[bf] many indications of successive periods of glaciation near the northern end of the duck mountain. the most characteristic indications which he had witnessed consisted of stratified beds of silt, containing fresh-water shells, with fragments of plants and fish similar to those living in the lakes of the region at the present time. [footnote bf: bulletin of the geological society of america, vol. i, pp. - .] reviewing these facts with reference to their bearing upon the point under consideration, we grant, at the outset, that they do indicate a successive retreat and readvance of the ice over extensive areas. this is specially clear with respect to the vegetal deposits interstratified with beds of glacial origin. but the question at issue concerning the interpretation of these phenomena is, do they necessarily indicate absolutely distinct glacial epochs separated by a period in which the ice had wholly disappeared from the glaciated area to the north? that they do, is maintained by president chamberlin and many others who have wide acquaintance with the facts. that they do not certainly indicate a complete disappearance of the ice during an extensive interglacial epoch, is capable, however, of being maintained, without forfeiting one's rights to the respect of his fellow-geologists. the opposite theory is thus stated by dr. robert bell: "it appears as if all the phenomena might be referred to one general glacial period, which was long continued, and consequently accompanied by varying conditions of temperature, regional oscillations of the surface, and changes in the distributions of sea and land, and in the currents in the ocean. these changes would necessarily give rise to local variations in the climate, and might permit of vegetation for a time in regions which need not have been far removed from extensive glaciers."[bg] [footnote bg: bulletin of the geological society of america, vol. i, pp. - .] at my request, professor j. e. todd, of iowa, whose acquaintance with the region is extensive, has kindly written out for me his conclusions upon this subject, which i am permitted to give in his own words: "i am not prepared to write as i would like concerning the forest-beds and old soils. i will, however, offer the following as a partial report. i have come to think that there is considerable confusion on the subject. i believe there are five or six different things classed under one head. " . _recent much and soils._--the finest example i have found in the whole missouri valley was twenty feet below silt and clay, in a basin inside the outer moraine, near grand view, south dakota. from my examination of the reported old soil near albia, iowa, i think the most rational way of reconciling the conflicting statements concerning it is that it also belongs to this class. " . _peat or soil under loess._--this does not signify much if the loess was formed in a lake subject to orographic oscillations, or if, as i am coming to believe, it is a fluviatile deposit of an oscillating river like the hoang-ho on the great chinese plain. it at least does not mean an interglacial epoch. " . _wood and dirt rearranged, not in situ._--this occurs either in subaqueous or in subglacial deposits. i have found drift-wood in the lower layers of the loess here, but not _in situ_. i have frequently found traces of wood in till in dakota, but always in an isolated way. i think, from reading statements about the deposits in eastern iowa, that most if not all of the cases are of this sort. two things have conspired to lead to this error: one, the influence of croll's speculation; and the other, the easy inference of many well-diggers, and especially well-borers, that what they pass through are always in layers. in this way a log becomes a forest-bed. scattered logs and muck fragments occurring frequently in a region, though at different levels, are readily imagined by an amateur geologist to be one continuous stratum antedating the glacier or floods (as the case may be in that particular region), when, in fact, it has been washed down from the margin of the transporting agent and is contemporaneous with it. i suspect the prevalence of wood in eastern iowa may be traced to a depression of the driftless region during the advance of the glacier, so as to bring the western side of that area more into the grasp of glacial agencies. " . _peat between subglacial tills._--if cases of this sort are found, they are in illinois, indiana, and ohio. professor worthen insisted that there were no interglacial soils or forest-beds in illinois; and in the cases mentioned in the state reports he repeatedly explains the sections given by his assistants, so as to harmonize them with that statement. i think he usually makes his explanations plausible. he was very confident in referring most of them, to preglacial times. his views, i suppose, will be published in the long-delayed volume, now about to be issued. " . _vegetable matter between glacial till and underlying berg till or other drift deposits._--when one remembers that the front of the great ice-sheet may have been as long in reaching its southern boundary as in receding from it, and with as many advance and retrograde movements, we can easily believe that much drift material would have outrun the ice and have formed deposits so far ahead of it that vegetation would have grown before the ice arrived to bury it. " . _preglacial soils, etc._--i believe that this will be found to include most in southern ohio, if not in illinois, as worthen claimed." the phenomena of the glacial period are too vast either to have appeared or to have disappeared suddenly. by whatever cause the great accumulation of ice was produced, the advance to the southward must have been slow and its disappearance must have been gradual, though, as we shall show a little later, the final retreat of the ice-front occupied but a short time relatively to the whole period which has elapsed since. as we shall show also, the advent of the ice period was probably preceded and accompanied by a considerable elevation of the northern part of the continent whether this elevation was contemporaneous upon both sides of the continent is perhaps an open question; but with reference to the area east of the rocky mountains, which is now under consideration, the centre of elevation was somewhere south of hudson bay. putting together what we know, from the nature of the case, concerning the accumulation and movement of glacial ice, and what we know from the relics of the great glacial invasion, which have enabled us to determine its extent and the vigour of its action, the course of events seems to have been about as follows: throughout the tertiary period a warm climate had prevailed over british america, greenland, and indeed over all the lands in proximity to the north pole, so far as explorers have been able to penetrate them. the vegetation characterizing these regions during the tertiary period indicates a temperature about like that which now prevails in north carolina and virginia. whatever may be said in support of the theory that the glacial period was produced by astronomical causes, in view of present facts those causes cannot be regarded as predominant; at most they were only co-operative. the predominant cause of the glacial period was probably a late tertiary or post-tertiary elevation of the northern part of the continents, accompanied with a subsidence in the central portion. of such a subsidence in the isthmus of panama indications are thought to be afforded by the occurrence of late tertiary or, more probably, post-tertiary sea-shells at a considerable elevation on the divide along the isthmus of panama, between the atlantic and pacific oceans. of this we shall speak more fully in a later chapter. fixing our thoughts upon what is known as the laurentian plateau, which, though now in the neighbourhood of but two thousand feet above the sea, was then much higher, we can easily depict in imagination the beginnings of the great "laurentide glacier," which eventually extended to the margin already delineated on the south and southwest in the united states, and spread northward and eastward over an undetermined area. year after year and century after century the accumulating snows over this elevated region consolidated into glacial ice and slowly pushed outward the surplus reservoirs of cold. for a long time this process of ice-accumulation may have been accompanied by the continued elevation of the land, which, together with the natural effect of the enlarging area of ice and snow, would tend to lower the temperature around the margin and to increase still more the central area of accumulation. the vigour of movement in any direction was determined partly by the shape of the valleys opening southward in which the ice-streams would naturally concentrate, and partly by those meteorological conditions which determine the extent of snow-fall over the local centres of glacial dispersion. for example, the general map of north america in the ice period indicates that there were two marked subcentres of dispersion for the great laurentide glacier, the eastern one being in labrador and the western one north of lake superior. in a general way the southern boundary of the glaciated region in the united states presents the appearance of portions of two circumferences of circles intersecting each other near the eastern end of lake erie. these circles, i am inclined to believe, represent the areas over which a semi-fluid (or a substance like ice, which flows like a semi-fluid) would disperse itself from the subcentres above mentioned. a study of the contour of the country shows that that also, in a general way, probably had something to do with the lines of dispersion. the western lobe of this glaciated area corresponds in its boundary pretty closely with the mississippi valley, having the ohio river approximately as its eastern arm and the missouri as its western, with the mississippi river nearly in its north and south axis. the eastern lobe has its farthest extension in the axis of the champlain and hudson river valleys, its western boundary being thrown more and more northward as the line proceeds to the west over the alleghany mountains until reaching the longitude of the eastern end of lake erie; but this southern boundary is by no means a water-level, nor is the contour of the country such that it could ever have been a water-level. but it conforms in nearly every particular to what would be the resultant arising from a pretty general southward flow of a semi-fluid from the two subcentres mentioned, meeting with the obstructions of the adirondacks in northern new york and of the broader appalachian uplift in northern pennsylvania. how far south the area of glacial accumulation may have extended cannot be definitely ascertained, but doubtless at an early period of the great ice age the northern portions of the appalachian range in new york, new england, new brunswick, and nova scotia became themselves centres of dispersion, while only at the height of the period did all their glaciers become confluent, so that there was one continuous ice-sheet. in the western portion of the area covered by the laurentide glacier, the depression occupied by the great lakes, especially lakes michigan and superior, evidently had a marked influence in directing the flow of ice during the stages which were midway between the culmination of the ice period and both its beginning and its end. this would follow from the great depth of these lakes, the bottom of lake michigan being feet below sea-level, and that of lake superior feet, making a total depth of water of about and , feet respectively. into these oblong depressions the ice would naturally gravitate until they were filled, and they would become the natural channels of subsequent movement in the direction of their longest diameters, while the great thickness of ice in them would make them the conservative centres of glacial accumulation and action after the ice had begun to retreat. these deductions from the known nature of ice and the known topography of the region are amply sustained by a study of the detailed map showing the glacial geology in the united states. but on this we can represent indeed only the marks left by the ice at various stages of its retreat, since, as already remarked, the marks of each stage of earlier advance would be obliterated by later forward movements. we may presume, however, that in general the marks left by the retreating ice correspond closely with those actually made and obliterated by the advancing movement. from observations upon the glaciers of switzerland and of alaska, it is found that neither the advance nor the retreat of these glaciers is constant, but that, in obedience to meteorologic agencies not fully understood, they advance and retreat in alternate periods, at one time receding for a considerable distance, and at other times regaining the lost ground and advancing over the area which has been uncovered by their retreat. "m. forel reports, from the data which he has collected with much care, that there have been in this century five periods in the alpine glaciers: of enlargement, from (?) to ; of diminution, from to ; of enlargement, from to ; of diminution, from to ; and of enlargement again, from onward. he remarks further that these periods correspond with those deduced by mr. c. lang for the variations for the precipitations and temperature of the air; and, consequently, that the enlargement of the glaciers has gone forward in the cold and rainy period, and the diminution in the warm and the dry."[bh] [footnote bh: american journal of science, vol. cxxxii, , p. .] when, now, we attentively consider the combination of causes necessary to produce the climatic conditions of the great ice age of north america, we shall be prepared to find far more extensive variations in the progress of the continental glacier, both during its advance and during its retreat, than are to be observed in any existing local glaciers. with respect to the arguments adduced in favor of a succession of glacial epochs in america the following criticisms are pertinent: . so far as we can estimate, a temporary retreat of the front, lasting a few centuries, would be sufficient to account for the vegetable accumulations that are found buried beneath the glacial deposits in southern ohio, indiana, central illinois, and iowa, while a temporary readvance of the ice would be sufficient to bury the vegetable remains beneath a freshly accumulated mass of till. thus, as dr. bell suggested, the interglacial vegetal deposits do not necessarily indicate anything more than a temporary oscillation of the ice-front, and do not carry with them the necessity of supposing a disappearance of the ice from the whole glaciated area. thus the introduction of a whole glacial period to account for such limited phenomena is a violation of the well-known law of parsimony, which requires us in our explanations of phenomena to be content with the least cause which is sufficient to produce them. in the present instance a series of comparatively slight oscillations of the ice-front during a single glacial period would seem to be sufficient to account for all the buried forests and masses of vegetal _débris_ that occur either in the united states or in the dominion of canada. . another argument for the existence of two absolutely distinct glacial periods in north america has been drawn from the greater oxidation of the clays and the more extensive disintegration of certain classes of the boulders found over the southern part of the glaciated area of the mississippi valley, than has taken place in the more northerly regions. without questioning this statement of fact (which, however, i believe to be somewhat exaggerated), it is not difficult to see that the effects probably are just what would result from a single long glacial period brought about by such causes as we have seen to be probably in operation in america. for if one reflects upon the conditions existing when the glacial period began, he will see that, during the long ages of warm climate which characterised the preceding period, the rocks must have been extensively disintegrated through the action of subaërial agencies. the extent to which this disintegration takes place can be appreciated now only by those who reside outside of the glaciated area, where these agencies have been in uninterrupted action. in the appalachian range south of the glaciated region the granitic masses and strata of gneiss are sometimes found to be completely disintegrated to a depth of fifty or sixty feet; and what seem to be beds of gravel often prove in fact to be horizontal strata of gneiss from which the cementing material has been removed by the slow action of acids brought down by the percolating water. now, there can be no question that this process of disintegration had proceeded to a vast extent before the glacial period, so that, when the ice began to advance, there was an enormous amount of partially oxidised and disintegrated material ready to be scraped off with the first advance of ice, and this is the material which would naturally be transported farthest to the south; and thus, on the theory of a single glacial period, we can readily account for the greater apparent age of the glacial _débris_ near the margin. this _débris_ was old when the glacial period began. . with reference to the argument for two distinct glacial periods drawn from the smaller apparent amount of glacial erosion over the southern part of the glaciated area, we have to remark that that would occur in case of a single ice-invasion as well as in case of two distinct ice-invasions, in which the later did not extend so far as the former. from the very necessity of the case, glacial erosion diminishes as the limit of the extent of the glaciation is approached. at the very margin of the glacier, motion has ceased altogether. back one mile from the margin only one mile of ice-motion has been active in erosion, while ten miles back from its front there has been ten times as much moving ice actually engaged in erosion, and in the extreme north several hundred times as much ice, thus it is evident that we do not need to resort to two glacial periods to account for the relatively small amount of erosion exhibited over the southern portion of our glaciated area. at the same time, it should be said that the indications of active glacial erosion near the margin are by no means few or small. in lawrence county, pennsylvania, on the very margin of the glaciated area, mr. max foshay[bi] has discovered very extensive glacial grooves, indicating much vigour of ice-action even beyond the more extensive glacial deposits which professor lewis and myself had fixed upon as the terminal moraine. in highland and butler counties, ohio, and in southwestern indiana and southern illinois, near the glacial margin, glacial grooves and striæ are as clear and distinct in many cases as can anywhere be found; while upon the surface of the limestone rocks within the limits of the city of st. louis, where the glacial covering is thin, and where disintegrating agencies had had special opportunities to work, i found very clear evidences of a powerful ice-movement, which had planed and scratched the rock surface; and at du quoin, illinois, as already related, the fragments thrown up from the surface of the rock, fifty or sixty feet below the top of the soil, were most beautifully planed and striated. it should be observed, also, that this whole area is so deeply covered with _débris_ that the extent of glacial erosion underneath is pretty generally hid from view. [footnote bi: bulletin of the geological society, vol. ii, pp. - .] . the uniformity of the distribution of the glacial deposits over the southern portion of the glaciated area in the mississippi valley is partly an illusion, due to the fact that there was a vast amount of deposition by water over that area during the earlier stages of the ice-retreat. this has been due partly to the gentler slope which would naturally characterise the borders of an area of elevation, and partly to an extensive subsidence which seems to have begun soon after the ice had reached its farthest extent of motion. it should be borne in mind that at all times a glacier is accompanied by the issue of vast streams of water from its front, and that these of course increase in volume when the climax has been reached and the ameliorating influences begin to melt away the accumulated mass of ice and to add the volume of its water to that produced by ordinary agencies. as these subglacial streams of water poured out upon the more gentle slopes of the area in front of the ice, they would distribute a vast amount of fine material, which would settle into the hollow places and tend to obscure the irregularities of the previous direct glacial deposit. such an instance came clearly under my own observation in the vicinity of yankton, in south dakota, where, upon visiting a locality some miles from any river, and to which workmen were resorting for sand, i found that the deposit occupied a kettle-hole, filling it to its brim, and had evidently been superimposed by a temporary stream of water flowing over the region while the ice was still in partial occupation of it. thus, no doubt, in many cases, the original irregularities of the direct glacial deposits have been obliterated, even where there has been no general subsidence. but, in the area under consideration, the loess, or loam, is so extensive that it is perhaps necessary to suppose that the central portions of the mississippi valley were subjected to a subsidence amounting to about five hundred feet; so that the glacial streams from the retreating ice-front met the waters of the ocean in southern illinois and indiana; thus accounting for the extensive fine silt which has done so much over that region to obscure the glacial phenomena. _west of the rocky mountains._ the glacial phenomena in the united states west of the rocky mountains must be treated separately, since american geologists have ceased to speak of an all-pervading ice-cap extending from the north pole. but, as already said, the glaciation of north america has proceeded from two definite centres of ice-accumulation, one of which we have been considering in the pages immediately preceding. the great centre of glacial dispersion east of the rocky mountains is the region south of hudson bay, and the vast ice-field spreading out from that centre is appropriately named the laurentide glacier. the movement of ice in this glacial system was outward in all directions from the laurentian hills, and extended west several hundred miles, well on towards the eastern foot of the rocky mountains. the second great centre of glacial dispersion occupies the vast cordilleran region of british columbia, reaching from the rocky mountains on the northeast to the coast range of the pacific on the southwest, a width of four hundred miles. the length is estimated by dr. dawson to be twelve hundred miles. the principal centre of ice-accumulation lies between the fifty-fifth and the fifty-ninth parallel. from this centre the movement was in all directions, but chiefly to the northwest and to the south. the movement of the cordilleran glaciers extended northwest to a distance of three hundred and fifty miles, leaving their moraines far down in the yukon valley on the lewes and pelly rivers.[bj] southward the cordilleran glacier moved to a distance of six hundred miles, extending to the columbia river, in the eastern part of the state of washington. [footnote bj: see george m. dawson, in science, vol. xi, , p. , and american geologist, september, , pp. - .] from this centre, also, the ice descended to the sea-level upon the west, and filled all the channels between vancouver's island and the mainland, as well as those in the alexander archipelago of alaska. south of vancouver's island a glacier pushed out through the straits of juan de fuca to an unknown distance. all the islands in puget sound are composed of glacial _débris_, resembling in every respect the terminal moraines which have been described as constituting many of the islands south of the new england coast. the ice-movement in puget sound, however, was probably northward, resulting from glaciers which are now represented by their diminutive descendants on the flanks of mount rainier. south of the columbia river the country was never completely enveloped by the ice, but glaciers extended far down in the valleys from all the lofty mountain-peaks. in idaho there are glacial signs from the summit of the rocky mountains down to the westward of lake pend d'oreille. in the yellowstone park there are clear indications that the whole area was enveloped in glacial ice. an immense boulder of granite, resting upon volcanic deposits, may be found a little west of inspiration point, on the yellowstone cañon. abundant evidences of glacial action are also visible down the yellowstone river to the vicinity of livingston, showing that that valley must have been filled with glacial ice to a depth of sixteen hundred feet. to the west the glaciers from the yellowstone park extended to the border of idaho, where a clearly marked terminal moraine is to be found in the tyghee pass, leading over from the western fork of the madison river into lewis fork of the snake river. south of yellowstone park the teton mountains were an important centre for the dispersion of local glaciers, but they did not descend upon the western side much below the , -foot level, and only barely came to the edge of the great snake river lava plains. to the east the movement from the teton mountains joined that from various other lofty mountains, where altogether they have left a most intricate system of glacial deposits, in whose reticulations jackson's lake is held in place. [illustration: fig. .--moraines of grape creek, sangre del cristo mountains, colorado (after stevenson).] in utah extensive glaciers filled all the northern valleys of the uintah mountains, and extended westward in the wahsatch range to the vicinity of salt lake city. the mountain region of colorado, also, had its glaciers, occupying the head-waters of the arkansas, the platte, the gunnison, and the grand rivers. the most southern point in the rocky mountains at which signs of local glaciers have been noted is near the summits of the san juan range, in southwestern colorado. here a surface of about twenty-five square miles, extending from an elevation of , feet down to , feet, shows every sign of the former presence of moving ice. the greater part of the glaciation in colorado is confined to elevations above , feet. the whole range of the sierra nevada through oregon, and as far south as the yosemite valley in california, formerly sustained glaciers of far greater size than any which are now found in those mountains. in general these glaciers were much longer on the western side of the sierra nevada than on the eastern. on the eastern side glaciers barely came down to lake tahoe and lake mono in california. the state of nevada seems to have been entirely free from glaciers, although it contains numerous mountain-peaks more than ten thousand feet high. in the yosemite cañon glaciers extended down the merced river to the mouth of the cañon; while in the tuolumne river, a few miles to the north, the glaciers which still linger about the peaks of mount dana filled the valley for a distance of forty miles. it is a question among geologists whether or not the glaciation west of the rocky mountains was contemporaneous with that of the eastern part of the continent. the more prevalent opinion among those who have made special study of the phenomena is that the development of the cordilleran glaciers was independent of that of the laurentide system. at any rate, the intense glaciation of the pacific coast seems to have been considerably later than that of the atlantic region. of this we will speak more particularly in discussing the questions of the date and the cause of the glacial period. it is sufficient for us here simply to say that, from his extensive field observations throughout the cordilleran region, dr. george m. dawson infers that there have been several successive alternations of level on the pacific coast corresponding to successive glacial and interglacial epochs, and that when there was a period of elevation west of the rocky mountains there was a period of subsidence to the east, and _vice versa_. in short, he supposes that the east and west for a long time played a game of seesaw, with the rocky mountains as the fulcrum. we give his scheme in tabulated form. _scheme of correlation of the phenomena of the glacial period in the cordilleran region and in the region of the great plains._ cordilleran region. region of the great plains. cordilleran zone at a high correlative subsidence and elevation. period of most severe submergence of the great plains, glaciation and maximum development with possible contemporaneous of the great cordilleran glacier. increased elevation of the laurentian axis and maximum development of ice upon it. deposition of the lower boulder-clay of the plains. gradual subsidence of the correlative elevation of the cordilleran region and decay of the western part, at least, of the great glacier, with deposition of great plains, which was probably the boulder-clay of the interior more or less irregular and led to plateau and the yukon basin, of the the production of extensive lakes lower boulder-clay of the littoral in which interglacial deposits, and probably also, at a later stage including peat, were formed. (and with greater submergence), of the interglacial silts of the same region. re-elevation of the cordilleran correlative subsidence of the region to a level probably as high plains, which (at least in the as or somewhat higher than the western part of the region) present. maximum of second period exceeded the first subsidence and of glaciation. extended submergence to the base of the rocky mountains near the forty-ninth parallel. formation of second boulder-clay, and (at a later stage) dispersion of large erratics. partial subsidence of the correlative elevation of the cordilleran region, to a level plains, or at least of their about , feet lower than the western portion, resulting in a present. long stage of stability. condition of equilibrium as glaciers of the second period between the plains and the considerably reduced. upper cordillera, their _relative_ boulder-clay of the coast probably levels becoming nearly as at formed at this time, though perhaps present. probable formation of the in part during the second maximum missouri coteau along a shore-line of glaciation. during this period of rest. renewed elevation of the simultaneous elevation of the great cordilleran region, with one plains to about their present well-marked pause, during which the level, with final exclusion of littoral stood about feet lower waters in connection with the sea. than at present. glaciers much lake agassiz formed and eventually reduced, and diminishing in drained towards the close of this consequence of general amelioration period. this simultaneous movement of climate towards the close of the in elevation of both great areas glacial period. may probably have been connected with a more general northern elevation of land at the close of the glacial period. in new zealand the marks of the glacial period are unequivocal the glaciers which now come down from the lofty mountains upon the south island of new zealand to within a few hundred feet of the sea then descended to the sea-level. the longest existing glacier in new zealand is sixteen miles, but formerly one of them had a length of seventy-eight miles. one of the ancient moraines contains a boulder from thirty to forty feet in diameter, and the amount of glacial _débris_ covering the mountain-sides is said to be enormous. reports have also been recently brought of signs of ancient glaciers in australia. [illustration: fig. .--generalised view of the whole glaciated region of north america. the area of motionless ground-ice is shown by the white lines in northern part of alaska.] according to darwin, there are distinct signs of glaciation upon the plains of patagonia sixty or seventy miles east of the foot of the mountains, and in the straits of magellan he found great masses of unstratified glacial material containing boulders which were at least one hundred and thirty miles away from their parent rock; while upon the island of chiloe he found embedded in "hardened mud" boulders which must have come from the mountain-chains of the continent. agassiz also observed unquestionable glacial phenomena on various parts of the fuegian coast, and indeed everywhere on the continent south of latitude °. between concepcion and arauco, in latitude °, agassiz observed, near the sea-level, a glacial surface well marked with furrows and scratches, and as well preserved, he says, "as any he had seen under the glaciers of the present day." [illustration: fig. .--quartzite boulder of cubic metres, on mont lachat, metres above the valley of the belley, in ain, france (falsan).] chapter vi. ancient glaciers in the eastern hemisphere. about two million square miles of northern europe were covered with perennial ice during the glacial period. from the scratches upon the rocks, and from the direction in which material has been transported, it is evident that the main centre of radiation is to be found in the mountains of scandinavia, and that the glaciers still existing in norway are the lineal descendants of those of the great ice age. so shallow are the baltic sea and the german ocean, that their basins were easily filled with ice, upon which scandinavian boulders could be transported westward to the east shore of england, southward into the plains of germany, and eastward far out upon the steppes of russia. the islands north of scotland bear marks also of an ice-movement from the direction of norway. if scotland itself was not overrun with scandinavian glaciers, the reason was that it had ice enough of its own, and from its highlands set up a counter-movement, which successfully resisted the invasion from the scandinavian peninsula. but, elsewhere in europe, scandinavian ice moved freely outward to the extent of its capacity. then, as now also, the alps furnished centres for ice-movement, but the glaciers were limited to the upper portions of the valleys of the rhône, the rhine, and the danube upon the west and north, and to a still smaller area upon the southern side. [illustration: fig. . map showing glaciated areas in north america and europe.] _central and southern europe._ the main centres of ice-movement in the alps during the glacial period are the same as those which furnish the lingering glaciers of the present time. from the water-shed between the rhine, the rhône, and the aar, glaciers of immense size descended all the valleys now occupied by those streams. the valley of the rhône between the bernese and the pennine alps was filled with a glacier of immense depth, which was maintained by fresh supplies from tributaries upon either side as far down as martigny. glacial markings at the head of the rhône valley are found upon the schneestock,[bk] at an elevation above the sea of about , feet ( , metres), or about , feet above the present surface of the rhône glacier. at fiesch, about twenty miles below, where tributaries from the bernese oberland snow-fields were received, the thickness of the glacier was upwards of , feet ( , metres). near martigny, about fifty miles farther down the valley, where the glacier was abruptly deflected to the north, the depth of the ice was still upwards of , metres. from martigny northward the thickness of the ice decreased rapidly for a few miles, where, at the enlargement of the valley above the head of lake geneva, it was less than , metres in thickness, and spread out over the intervening plain as far as chasseron, with a nearly level surface, transporting, as we have before said, alpine boulders to the flanks of the juras, and landing them about , feet ( , metres) above the level of lake geneva. the width of the main valley is here about fifty miles, making the slope of the surface of the ice about twenty feet to the mile. [footnote bk: a. falsan's la période grlaciaire étudiée principalement en france et en suisse, chapitre xv.] from its "vomitory," at the head of lake geneva, the ice of the ancient rhône glacier spread to the right and to the left, while its northern boundary was abruptly terminated by the line of the jura mountains. the law of glacial motion was, however, admirably illustrated in the height to which the ice rose upon the flanks of the jura. at chasseron, in the direct line of its onward motion, it rose to its highest point, while both to the southwest and to the northeast, along the line of the juras, the ice-action was limited to constantly decreasing levels. down the valley of the rhône the direction of motion was determined by the depression of lake geneva, at the lower end of which it received its main tributary from mont blanc, which had come down from chamouni through the valley of the river arve. from this point it was deflected by a spur of the jura mountains more and more southward to the vicinity of culoz, near the mouth of lake bourget. here the glacier coming down from the western flanks of the alps, through the upper valley of the isère, past chambéry, became predominant, and deflected the motion to the west and north, whither the ice extended to a line passing through bourg, lyons, and vienne, leaving upon one of the eminences on which lyons is built a boulder several feet in diameter, which is duly preserved and labelled in the public park in that portion of the city. farther south, glaciers of less extent marked the alps most of the way to the mediterranean, but they were not at all comparable in size to those from the central region. to the right of lake geneva the movement started by the rhône glacier spread eastward, being joined in the vicinity of berne by the confluent ice-stream which descended from the north flank of the bernese oberland, through the valley of the aar. these united streams filled the whole valley with ice as far down as soleure.[bl] [footnote bl: see map of rhône glacier, on p. .] [illustration: map of glacial movements in france and switzerland.] farther eastward, other ice-streams from the alps became predominant, one of which, moving down the reuss, deployed out upon the country lying north of lucerne and zug. still farther down, the ancient glacier which descended the limmatt spread itself out over the hills and lowlands about zürich, one of its moraines of retrocession nearly dividing the lake into two portions. guyot and others have shown that the superficial deposits of this portion of switzerland are just such as would be distributed by glaciers coming down from the above-mentioned alpine valleys. uniting together north of zürich, these glaciers pushed onward as far as the rhine below schaffhausen. in frickthal the glacial ice was still , feet thick, and at kaisterberg between and feet. at lucerne there is a remarkable exposure of pot-holes, and a glaciated surface such as could be produced only by the combined action of moving ice and running water; thus furnishing to tourists an instructive object-lesson. among the remarkable instances of boulders transported a long distance in switzerland, is that of a block of granite carried from the valais to the vicinity of soleure, a distance of one hundred and fifteen miles, which weighs about , tons. "the celebrated pierre-à-bot, above neufchâtel, measures ' × ' × ', and contains about , cubic feet of stone; while the pierre-des-marmettes, near monthey, contains no less than , cubic feet." the ancient glacier of the rhine, receiving its initial impulse in the same centre as that of the rhône, fully equalled it in all its dimensions. descending eastward from its source near the schneestock to chur, a distance of fifty miles, it turned northward and continued forty-five miles farther to the head of lake constance, where it spread out in fan-shape, extending northwest to thiengen, below schaffhausen, and covering a considerable area north and northeastward of the lake, reaching in the latter direction ulm, upon the danube--the whole distance of the movement being more than one hundred and fifty miles. through other valleys tributary to the danube, glaciers descended upon the upper plains of bavaria, from the tyrolese alps to the vicinity of munich. from gross glockner as a centre in the noric alps, vast rivers of ice, of which the pasterzen glacier is the remnant, poured far down into the valleys of the inn and the enns on the north and into that of the drave on the southeast. farther eastward in this part of europe the mountains seem to have been too low to have furnished centres for any general dispersion of glacial ice. [illustration: fig. .--map showing the lines of _débris_ extending from the alps into the plains of the po (after lyell). _a._ crest of the alpine water-shed; _b._ névé-fields of the ancient glaciers; _c._ moraines of ancient glaciers.] upon the south side of the alps the ancient glaciers spread far out upon the plains of lombardy, where moraines of vast extent and of every description enable the student to determine the exact limits of the ancient ice-action. from the southern flanks of mont blanc and monte rosa, and from the snow-fields of the western alps, glaciers of great volume descended into the valley of dora baltea (vale of aosta), and on emerging from the mountain valley spread out over the plains around ivrea, leaving moraine hills in some instances , feet in height. the total length of this glacier was as much as one hundred and twenty miles. from the snow-fields in the vicinity of mont cenis, also, glaciers extended down the dora ripera to the vicinity of turin, and down other valleys to a less extent. the lateral moraines of the diore, on the south side of mont blanc, at the head of the dora baltea, are , feet above the present river, and extend upon the left bank for a distance of twenty miles. from the eastern alps, glaciers descended through all the valleys of the italian lakes and deposited vast terminal moraines, which still obstruct the drainage, and produce the charming lakes of that region. a special historic interest pertains to the series of concentric moraines south of lake garda, since it was in the reticulations of this glacial deposit that the last great battle for italian liberty was fought on june , . defeated in the engagements farther up the valley of the po, the austrian general benedek took his final stand to resist the united forces of france and italy behind an outer semicircle of the moraine hills south of this lake (some of which are or feet above the surrounding country), with his centre at solferino, about ten miles from peschera. here, behind this natural fortification, he awaited the enemy, who was compelled to perform his manoeuvres on the open plain which spread out on every side. but the natural fortifications furnished by the moraine hills were too extensive to be defended by an army of moderate size. the troops of napoleon and victor immanuel concentrated at solferino and broke through the line. thus the day was lost to the austrians, and they retired from lombardy, leaving to italy both the artificial and the natural fortifications that guard the southern end of this important entrance to the tyrolese alps. when once his attention is called to the subject, the traveller upon the railroad cannot fail to notice this series of moraines, as he enters it through a tunnel at lonato on the west, and emerges from it at soma campagna, eighteen or twenty miles distant to the east. a monument celebrating the victory stands upon a moraine hill about half-way between, at martino della battaglie. in other portions of central and southern europe the mountains were too low to furnish important centres for glacial movements. still, to a limited extent, the signs of ancient glaciers are seen in the mountains of the black forest, in the harz and erzgebirge, and in the carpathians on the east and among the apennines on the south. in spain, also, there were limited ice-fields on the higher portions of the sierra nevada and in the mountains of estremadura, and perhaps in some other places. in france, small glaciers were to be found in the higher portions of the auvergne, of the morvan, of the vosges, and of the cevennes; while, from the pyrenees, glaciers extended northward throughout nearly their whole extent. the ice-stream descending from the central mass of maladetta through the upper valley of the garonne, was joined by several tributaries, and attained a length of about forty-five miles. _the british isles._ during the climax of the glacial period the hebrides to the north of scotland were covered with ice to a depth of , feet. how far westward of this it moved out to the sea, it is of course impossible to tell. but in the channels between the hebrides and scotland it is evident that the water was completely expelled by the ice, and that, from a height of , feet above the hebrides to the northern shores of scotland, there was a continuous ice-field sloping southward at the rate of about twenty-five feet a mile. scotland itself was completely enveloped in glacial ice. prevented by the scandinavian glacier from moving eastward, the scotch movement was compelled to be westward and southward. on the southwest the ice-stream reached the shores of ireland, and became confluent with the glaciers that enveloped that island, completely filling the irish sea. there are so many controverted points respecting the glacial geology of england, and they have such an important bearing upon the main question of this volume, that a pretty full discussion of them will be necessary. i have recently been over enough of the ground myself to become satisfied of the general correctness of the views entertained by my late colleague, the lamented professor henry carvill lewis, whose death in took place before the publication of his most mature conclusions. but the lines of investigation to which he gave so powerful an impulse have since been followed out by an active body of scientific observers. to give the statement of facts greater precision and authority, i have committed the preparation of it to the secretary of the northwest of england boulder committee, percy f. kendall, f. g. s., lecturer on geology at the yorkshire college, leeds, and at the stockport technical school, england.[bm] [footnote bm: mr. kendall's contribution extends to page .] "all the characteristic evidences of the action of land-ice can be found in the greatest perfection in many parts of england and wales. drumlins, kames, _roches moutonnées_, far-travelled erratics, terminal moraines, and perched blocks, all occur. there are, besides, in the wide-spread deposits of boulder-clay which cover so many thousands of square miles on the low grounds lying on either side of the pennine chain, evidences of the operation of ice-masses of a size far exceeding that of the grandest of existing european glaciers. but, while the proofs of protracted and severe glaciation are thus patent, there are, nevertheless, many apparently anomalous circumstances which arrest the attention when the whole country is surveyed. the glacial phenomena appear to be strictly limited to the country lying to the northward of a line extending from the bristol channel to the mouth of the thames; and within the glaciated area there are many extensive tracts of land devoid of 'drift' or other indications of ice-action. "by comparison with the phenomena displayed in the north american continent, english glacial geology must seem puny and insignificant; but, just as with the features of the 'solid geology,' we have compressed within the narrow limits of our isles an epitome of the features which across the atlantic require a continent for their exposition. it has resulted from this concentration that english geology requires a much closer and more minute investigation. and the difficulty which has been experienced by glacial geologists of dealing with an involved series of facts has, in the absence of any clue leading to the co-ordination of a vast series of more or less disconnected observations, resulted in the adoption, to meet certain local anomalies, of explanations which were very difficult if not impossible of reconciliation with facts observed in adjacent areas. thus, to account for shell-bearing drift extending up to the water-shed on one side of a lofty range of hills, a submergence of the land to a depth of , feet has been postulated; leaving for independent explanation the fact, that the opposite slopes of the hills and the low ground beyond were absolutely destitute of drift or of any evidence of marine action. "in the following pages i must adopt a somewhat dogmatic tone, in order to confine myself within the limits of space which are imposed; and trust rather to the cohesion and consistency of the explanations offered and to a few pregnant facts than to the weighing and contrasting of rival theories. "the facts point conclusively to the action in the british isles of a series of glaciers radiating outward from the great hill chains or clusters, and, as the refrigeration progressed, becoming confluent and moving though in the same general direction, yet with less regard to the minor inequalities of the ground. during these two stages many glaciers must have debouched upon the sea-coast, with the consequent production of icebergs, which floated off with loads of boulders and dispersed them in the random fashion which is a necessary characteristic of transport by floating ice. "with a further accentuation of the cold conditions the discharge of bergs from terminal fronts which advanced into the extremely shallow seas surrounding the british shores would be quite inadequate to relieve the great press of ice, and a further coalescence of separate elements must have resulted. in the case of enclosed seas--as, for example, the irish sea--the continued inthrust of glacier-ice would expel the water completely; and the conjoined ice-masses would take a direction of flow the resultant of the momentum and direction of the constituent elements. in other cases--as, for example, in the north sea--extraneous ice approaching the shores might cause a deflection of the flow of the native glaciers, even though the foreign ice might never actually reach the shore. "to such a system of confluent glaciers, and to the separate elements out of which they grew, and into which, after the culmination, they were resolved, i attribute the whole of the phenomena of the english and welsh drift. and only at one or two points upon the coast, and raised but little above the sea-level, can i recognise any signs of marine action. "_the preglacial level of the land._--there is very little direct evidence bearing upon this point. in norfolk the famous forest bed, with its associated deposits, stands at almost precisely the level which it occupied in preglacial times. at sewerby, near flamborough head, there is an ancient beach and 'buried cliff' which the sea is now denuding of its swathing of drift-deposits, and its level can be seen to be almost absolutely coincident with the present beach. mr. lamplugh, whose description of the 'drifts of flamborough head,'[bn] constitutes one of the gems of glacial literature, considers that there is clear evidence that the land stood at this level for a long period. the beach is covered by a rain-wash of small extent, and that in turn by an ancient deposit of blown sand, while the lowest member of the drift series of yorkshire covers the whole. mr. lamplugh thinks that the blown sand may indicate a slight elevation of the land; but the beach appears to me to be the storm beach, and the reduction in the force of the waves such as would result from the approach of an ice-front a few miles to the seaward would probably produce the necessary conditions. [footnote bn: quarterly journal of the geological society, vol. xlvii.] "six miles to the northward of flamborough, at speeton, a bed of estuarine silt containing the remains of mollusca in the position of life occurs at an altitude of ninety feet above high-water mark. mr. lamplugh inclines to the opinion that this bed is of earlier date than the 'buried cliff'; he also admits the possibility that its superior altitude may be due to a purely local upward bulging of the soft lower cretaceous clays upon which the estuarine bed rests by the weight of the adjacent lofty chalk escarpment. "the evidence obtained from inland sections and borings in different parts of england has been taken to indicate a greater altitude in preglacial times. thus, in essex, deep-borings have revealed the existence of deep drift-filled valleys, having their floors below sea-level. the valley of the mersey is a still better example. numerous borings have been made in the neighbourhood of widnes and at other places in the lower reaches of the river, making it clear that there is a channel filled with drift and extending to feet below mean sea-level. this, with several other instances, has been taken to indicate a greater altitude for the land in preglacial times, since a river could not erode its channel to such a depth below sea-level. the argument appears inconclusive for one principal reason: no mention is made of any river gravels or other alluvium in the borings. indeed, there is an explicit statement that the deposits are all glacial, showing that the channel must have been cleared out by ice. this, therefore, leaves open the vital question, whether the deposits removed were marine or fluviatile. it may be remarked that the great estuary of the mersey has undoubtedly been produced by a post-glacial (and probably post-roman) movement of depression. "_the preglacial climate._--in all speculations regarding the cause of the glacial epoch, due account must be taken of the undoubted fact that it came on with extreme slowness and departed with comparative suddenness. in the east of england an almost perfect and uninterrupted sequence of deposits is preserved, extending from the early part of the pliocene period down to the present day. "these in descending order are: " . post-glacial sands, gravels, etc. " . glacial series. " . the 'forest bed' and associated marine deposits. " . chillesford clay and sand. " . the many successive stages of the red crag. (the norwich crag is a local variation of the upper part of the red crag.) " . the coralline crag. "the fossils preserved in these deposits, apart from the physical indications, exhibit the climatal changes which accompanied their deposition. the coralline crag contains a fauna consisting mainly of species which now range to the mediterranean, many of them being restricted to the warm southern waters. associated with these are a few boreal forms, but they are represented in general by few individuals. here and there in the deposits of this age far-travelled stones are to be found, but they are always accounted great rarities. "the red crag consists of an irregular assemblage of beaches and sand-banks of widely different ages, but their sequence can be made out with ease by a study of the fauna. in the oldest deposits, mediterranean species are very numerous, while the boreal forms are comparatively rare; but in successive later deposits the proportions are very gradually reversed, and from the overlying chillesford series the mediterranean species are practically absent. the physical indications run _pari passu_ with the paleontological, and in the newer beds of the red crag far-travelled stones are common. "in the forest bed series there is a marine band--the _leda myalis_ bed--which contains an almost arctic assemblage of shells; while at about the same horizon plant remains have been found, including such high northern species as _salix polaris_ and _betula nana_. "the glacial deposits do not, in my opinion, contain anywhere in england or wales a genuine intrinsic fauna, such shells as occur in the east anglian glacial deposits having been derived in part from a contemporary sea-bed, and, for the rest, from the older formations, down perhaps to the coralline crag. in the post-glacial deposits we have hardly any trace of a survival of the boreal forms, and i consider that the whole marine fauna of the north sea was entirely obliterated at the culmination of the glacial epoch, and that the repeopling in post-glacial times proceeded mainly from the english channel, into which the northern forms never penetrated. "_the great glacial centres._ "where such complex interactions have to be described as were produced by the conflicting glaciers of the british isles it is difficult to deal consecutively with the phenomena of any one area, but with short digressions in explanation of special points it may be possible to accomplish a clear presentation of the facts. "_wales._--the phenomena of south wales are comparatively simple. great glaciers travelled due southward from the lofty brecknock beacons, and left the characteristic _moutonnée_ appearance upon the rocky bed over which they moved. the boulder-transport is in entire agreement with the other indications, and there are no shells in the drift. the facts awaiting explanation are the occurrence in the boulder-clays of glamorganshire, at altitudes up to four hundred feet, of flints, and of igneous rocks somewhat resembling those of the archæan series of the wrekin. at clun, in shropshire, a train of erratics (see map) has been traced back to its source to the westward. on the west coast, in cardigan bay, the boulders are all such as might have been derived from the interior of wales. at st. david's peninsula, pembrokeshire, striæ occur coming in from the northwest, and, taken with the discovery of boulders of northern rocks, may point to a southward extension of a great glacier produced by confluent sheets that choked the irish sea. information is very scanty regarding large areas in mid-wales, but such as can be gathered seems to point to ice-shedding having taken place from a north and south parting line. in north wales, much admirable work has been done which clearly indicates the neighbourhood of great arenig (arenig mawr) as the radiant point for a great dispersal of blocks of volcanic rock of a characteristic welsh type. "_ireland._--a brief reference must be made to ireland, as the ice which took origin there played an important part in bringing about some strange effects in english glaciation, which would be inexplicable without a recognition of the causes in operation across the irish sea. ireland is a great basin, surrounded by an almost continuous girdle of hills. the rainfall is excessive, and the snow-fall was probably more than proportionately great; therefore we might expect that an ice-sheet of very large dimensions would result from this combination of favouring conditions. the irish ice-sheet appears to have moved outward from about the centre of the island, but the main flow was probably concentrated through the gaps in the encircling mountains. "_galloway._--the great range of granite mountains in the southwestern corner of scotland seems to have given origin to an immense mass of ice which moved in the main to the southward, and there are good grounds for the belief that the whole ice-drainage of the area, even that which gathered on the northern side of the water-shed, ultimately found its way into the irish sea basin and came down coastwise and across the low grounds of the rinns of galloway, being pushed down by the press of highland ice which entered the firth of clyde. it is a noteworthy fact that marine shells occur in the drift in the course taken by the ice coming on to the extremity of galloway from the clyde. "_the lake district._--a radial flow of ice took place down the valleys from about the centre of the cumbrian hill-plexus, but movement to the eastward was at first forbidden by the great rampart of the cross fell escarpment, which stretches like a wall along the eastern side of the vale of eden. "during the time when the cumbrian glaciers had unobstructed access to the solway frith, to the irish sea, and to morecambe bay, the dispersal of boulders of characteristic local rocks would follow the ordinary drainage-lines; but, as will be shown later, a state of affairs supervened in the irish sea which resulted, in many cases, in a complete reversal of the ice-flow. "_the pennine chain_ was the source of glaciers of majestic dimensions upon both its flanks in the region north of skipton, but to the southward of that breach in the chain (see map) no evidence is obtainable of any local glaciers. "_the confluent glaciers._ "with the growth of ice-caps upon the great centres a condition of affairs was brought about in the irish sea productive of results which will readily be foreseen. the enormous volumes of ice poured into the shallow sea from north, south, east, and west, resulted in such a congestion as to necessitate the initiation of some new systems of drainage. "_the irish sea glacier._--the ice from galloway, cumbria, and ireland became confluent, forming what the late professor carvill lewis termed 'the irish sea glacier,' and took a direction to the southward. here it came in diametrical conflict with the northward-flowing element of the welsh sheet, which it arrested and mastered; and the irish sea glacier bifurcated, probably close upon the precipitous welsh coast to the eastward of the little orme's head, and the two branches flowed coastwise to eastward and westward, keeping near the shore-line. "the westerly branch swept round close to the coast in a southwesterly direction, and completely overrode anglesea; striating the rock-surfaces from northeast to southwest (see map), and strewing the country with its bottom-moraine, containing characteristic northern rocks, such as the galloway granites, the lavas and granites of the central and western portions of the lake district, and fragments of shells derived from shell-banks in the irish sea. one episode of this phase of the ice-movement was the invasion of the first line of hills between the menai straits and snowdon. the gravels and sands of fridd-bryn-mawr, moel tryfaen, and moel-y-cilgwyn, are the coarser washings of the bottom-moraine, and consequently contain such rock-fragments and shells as characterise it. from moel-y-cilgwyn southward, evidence is lacking regarding the course taken by the glacier, but it probably passed over or between the rivals mountains (yr eifl), and down cardigan bay at some distance from the coast in confluence with the ice from mid-wales; and, as i have suggested, may have passed over st. david's head. "returning now towards the head of the glacier we may follow with advantage its left bank downward. the ice-flow on the cumberland coast appears to have resembled very much that in north wales. a great press of ice from the northward (galloway) seems to have had a powerful 'easting' imparted to it by the conjoint influences of the thrust of the irish ice and the inflow of ice from the clyde. whatever may have been the cause, the effect is clear: about ravenglass cleavage took place, and a flow to northward and to southward, each bending easterly. by far the larger mass took a southerly course and bent round black combe, over walney, and a strip of the mainland about barrow in furness, and out into and across morecambe bay. its limits are marked in the field by the occurrence of the same rocks which characterise it in anglesea, viz., the granites of galloway and of west and central cumbria. "the continued thrust shouldered in the glacier upon the mainland of lancashire, but the precise point of emergence has not yet been traced, though it cannot be more than a few miles from the position indicated on the map. i should here remark, that all along the boundaries the irish sea glacier was confluent with local ice, except, probably, in that part of the pennine chain to the southward of skipton. down to skipton there was a great mass of pennine ice which was compelled to take an almost due southerly course, and thus to run directly athwart the direction of the main hills and valleys. a sharp easterly inflection of the irish sea glacier carried it up the valley of the ribble, and thence, under the shoulder of pendle, to burnley, where scottish granites are found in the boulder-clay. "on the summit of the pennine water-shed, at heald moor, near todmorden ( , feet), boulder-clay has been found containing erratics belonging to this dispersion; while in the gorge of the yorkshire calder, which flows along the eastern side of the same hill, not a vestige of such a deposit is to be found, saving a few erratic pebbles at a distance of eight or ten miles, which were probably carried down by flood-wash from the edge of the ice. "from this point the limits of the ice may be traced along the flanks of the pennine chain at an average altitude of about , feet. "at one place the erratics can be traced to a position which would indicate the formation of an extra-morainic lake having its head at a col about , feet above sea-level, separating it from the valley of an eastward-flowing stream, the wye, about twelve miles down which a few granite blocks have been found. other extra-morainic lakes must have been formed, but very little information has been collected regarding them. the irish sea glacier can be shown to have spread across the whole country to the westward of the line i have traced, and beyond the estuary of the dee. "i may now follow its boundaries on the welsh coast, and pursue the line to the final melting-place of the glacier. from the little orme's head the line of confluence with the native ice is pretty clearly defined. it runs in, perhaps, half a mile from the shore, until the broad low tract of the vale of clwyd is reached. here the northern ice obtained a more complete mastery, and pushed in even as far as denbigh. this extreme limit was probably attained as a mere temporary episode. horizontal striæ on a vertical face of limestone on the crags dominating the mouth of the vale on the eastern side attest beyond dispute the action of a mass of land-ice moving in from the north. "i may here remark, that in this district the deposits furnish a very complete record of the events of the glacial period. in the cliffs on the eastern side of the little orme's head, and at several other points along the coast towards the east, a sequence may be observed as follows: " . boulder-clay with northern erratics and shells. " . sands and gravels with northern erratics and shells. " . boulder-clay with northern erratics and shells. " . boulder-clay with welsh erratics and no shells. "a similar succession is to be seen in the vale of clwyd. the interpretation is clear: in the early stages of glaciation the welsh ice spread without hindrance to, and laid down, bed no. ; then the northern ice came down, bringing its typical erratics and the scourings of the sea-bottom, and laid down the variable series of clays, sands, and gravels which constitute nos. , , and of the section. [illustration: fig. .--the cefn cave, in vale of clwyd. (trimmer.) _a_, entrance; _b_, mud with pebbles and wood covered with stalagmite; _c_, mud, bones, and angular fragments of limestone; _d_, sand and silt, with fragments of marine shells; _e_, fissure; _f_, northern drift; _g_, cave cleared of mud; _h_, river elwy, feet below; _i_, limestone rock.] "in the vale of clwyd an additional interest is imparted to the study of the drift from the circumstance that the remains of man have been found in deposits in caves sealed with drift-beds. the best example is the cae gwyn caves, in which flint implements and the bones and teeth of various extinct animals were found embedded in 'cave-earth' which was overlaid by bedded deposits of shell-bearing drift, with erratics of the northern type. "it has been supposed that the drift-deposits were marine accumulations; but it is inconceivable that the cave could ever have been subjected to wave-action without the complete scouring out of its contents. "to resume the delineation of the limits of the great irish sea glacier: from the vale of clwyd the boundary runs along the range of hills parallel to the estuary of the dee at an altitude of about nine hundred feet. as it is traced to the southeast it gradually rises, until at frondeg, a few miles to the northward of the embouchure of the yale of llangollen, it is at a height of , feet above sea-level. thence it falls to , feet at gloppa, three miles to the westward of oswestry, and this is the most southerly point to which it has been definitely traced on the welsh border, though scattered boulders of northern rocks are known to occur at church stretton. "along the line from the vale of clwyd to oswestry the boundary is marked by a very striking series of moraine-mounds. they occur on the extreme summits of lofty hills in a country generally almost driftless, and their appearance is so unusual that one--moel-y-crio--at least has been mistaken for an artificial tumulus. the limitation of the dispersal of northern erratics by these mounds is very clear and sharp; and mackintosh, in describing those at frondeg, remarked that, while no northern rocks extended to the westward of them, so no welsh erratics could be found to cross the line to the eastward. there are welsh erratics in the low grounds of cheshire and shropshire, but their distribution is sporadic, and will be explained in a subsequent section. "having thus followed around the edges of this glacier, it remains to describe its termination. it is clear that the ice must have forced its way over the low water-shed between the respective basins of the dee and the severn. so soon as this ridge (less than feet above the sea) is crossed, we find the deposits laid down by the glacier change their character, and sands and gravels attain a great predominance.[bo] near bridgenorth, and, at other places, hills composed of such materials attain an altitude of feet. from shrewsbury _via_ burton, and thence, in a semicircular sweep, through bridgenorth and enville, there is an immense concentration of boulders and pebbles, such as to justify the designation of a terminal moraine. to the southward, down the valley of the severn, existing information points to the occurrence merely of such scattered pebbles as might have been carried down by floods. in the district lying outside this moraine there is a most interesting series of glacial deposits and of boulders of an entirely different character. (see map.) [footnote bo: mackintosh, q. j. g. s.] "from the neighbourhood of lichfield, through some of the suburbs of birmingham, and over frankley hill and the lickey hills to bromsgrove, there is a great accumulation of welsh erratics, from the neighbourhood, probably, of arenig mawr. "the late professor carvill lewis suggested that these arenig rocks might have been derived from some adjacent outcrop of palæozoic rocks--a suggestion having its justification in the discoveries that had been made of cumbrian rocks in the midlands. to test the matter, an excavation was made at a point selected on frankley hill, and a genuine boulder-clay was found, containing erratics of the same type as those found upon the surface. "the explanation has since been offered that this boulder-clay was a marine deposit laid down during a period of submerge nee.[bp] apart from the difficulty that the boulder-clay displays none of the ordinary characteristics of a marine deposition, but possesses a structure, or rather absence of structure, in many respects quite inconsistent with such an origin, and contains no shells or other remains of marine creatures, it must be pointed out that no theory of marine notation will explain the distribution of the erratics, and especially their concentration in such numbers at a station sixty or seventy miles from their source. [footnote bp: proceedings of the birmingham philosophical society, vol. vi, part i, p. .] "upon the land-ice hypothesis this difficulty disappears. during the early stages of the glacial period the welsh ice had the whole of the severn valley at its mercy, and a great glacier was thrust down from arenig, or some other point in central wales, having an _initial direction_, broadly speaking, from west to east. this glacier extended across the valley of the severn, sweeping past the wrekin, whence it carried blocks of the very characteristic rocks to be lodged as boulders near lichfield; and it probably formed its terminal moraine along the line indicated. (see lozenge-shaped marks on the map.) as the ice in the north gathered volume it produced the great irish sea glacier, which pressed inland and down the vale of severn in the manner i have described, and brushed the relatively small welsh stream out of its path, and laid down its own terminal moraine in the space between the welsh border and the lickey hills. it seems probable that the welsh stream came mainly down the vale of llangollen, and thence to the lickey hills. boulders of welsh rocks occur in the intervening tract by ones and twos, with occasional large clusters, the preservation of any more connected trail being rendered impossible by the great discharge of water from the front of the irish sea glacier, and the distributing action of the glacier itself. "within the area in england and wales covered by the irish sea glacier all the phenomena point to the action of land-ice, with the inevitable concomitants of subglacial streams, extra-morainic lakes, etc. there is nothing to suggest marine conditions in any form except the occurrence of shells or shell fragments; and these present so many features of association, condition, and position inconsistent with, what we should be led to expect from a study of recent marine life, that conchologists are unanimous in declaring that not one single group of them is on the site whereon the shells lived. it is a most significant fact--one out of a hundred which could be cited did space permit--that in the ten thousand square miles of, as it is supposed, recently elevated sea-bottom, not a single example of a bivalve shell with its valves in apposition has ever been found! nor has a boulder or other stone been found encrusted with those ubiquitous marine parasites, the barnacles. "the evidences of the action of land-ice within the area are everywhere apparent in the constancy of direction of-- ( .) striæ upon rock surfaces. ( .) the terminal curvature of rocks. ( .) the 'pull-over' of soft rocks. ( .) the transportal of local boulders. ( .) the orientation of the long axes of large boulders. ( .) the false bedding of sands and gravels. ( .) the elongation of drift-hills. ( .) the relations of 'crag and tail.' there is a similar general constancy, too, in the directions of the striæ upon large boulders. upon the under side they run longitudinally from southeast (or thereabouts) to northwest, while upon the upper surface they originate at the opposite end, showing that the scratches on the under side were produced by the stone being dragged from northwest to southeast, while those on the top were the product of the passage of stone-laden ice over it in the same direction. "such an agreement cannot be fortuitous, but must be attributed to the operation of some agent acting in close parallelism over the whole area. to attribute such regularity to the action of marine currents is to ignore the most elementary principles of marine hydrology. icebergs must, in the nature of things, be the most erratic of all agents, for the direction of drift is determined--among other varying factors--by the draught of the berg. a mass of small draught will be carried by surface currents, while one of greater depth will be brought within the influence of under-currents; and hence it not infrequently happens that while floe-ice is drifting, say, to the southeast, giant bergs will go crashing through it to the northwest. there are tidal influences also to be reckoned with, and it is matter of common knowledge that flotsam and jetsam travel back and forth, as they are alternately affected by ebb and flood tide. "bearing these facts in mind, it is surely too much to expect that marine ice should transport boulders (how it picked up many of them also requires explanation) with such unfailing regularity that it can be said without challenge,[bq] 'boulders in this district [south lancashire and cheshire] never occur to the north or west of the parent rock.' the same rule applies without a single authentic exception to the whole area covered by the eastern branch of the irish sea glacier; and hence it comes about that not a single boulder of welsh rock has ever been recorded from lancashire. [footnote bq: brit. assoc. report, , p. .] "_the solway glacier._--the pressure which forced much of the irish sea ice against the cumbrian coast-line caused, as has been described, a cleavage of the flow near ravenglass, and, having followed the southerly branch to its termination in the midlands, the remaining moiety demands attention. "the 'easting' motion carried it up the solway frith, its right flank spreading over the low plain of northern cumberland, which it strewed with boulders of the well-known 'syenite' (granophyre) of buttermere. when this ice reached the foot of the cross fell escarpment, it suffered a second bifurcation, one branch pushing to the eastward up the valley of the irthing and over into tyneside, and the other turning nearly due southward and forcing its way up the broad vale of eden. "under the pressure of an enormous head of ice, this stream rose from sea-level, turned back or incorporated the native cumbrian glacier which stood in its path, and, having arrived almost at the water-shed between the northern and the southern drainage, it swept round to the eastward and crossed over the pennine water-shed; not, however, by the lowest pass, which is only some , feet above sea-level, but by the higher pass of stainmoor, at altitudes ranging from , to , feet. the lower part of the course of this ice-flow is sufficiently well characterised by boulders of the granite of the neighbourhood of dalbeattie in galloway; but on its way up the vale of eden it gathered several very remarkable rocks and posted them as way-stones to mark its course. one of these rocks, the permian brockram, occurs nowhere _in situ_ at altitudes exceeding feet, yet in the course of its short transit it was lifted about a thousand feet above its source. the shap granite (see radiant point on map) is on the northern side of the east and west water-sheds of the lake district, and reaches its extreme elevation, ( , feet) on wasdale pike; yet boulders of it were carried over stainmoor, at an altitude of , feet literally by tens of thousands. "this stainmoor glacier passed directly over the pennine chain, past the mouths of several valleys, and into teesdale, which it descended and spread out in the low grounds beyond. pursuing its easterly course, it abutted upon the lofty cleveland hills and separated into two streams, one of which went straight out to sea at hartlepool, while the other turned to the southward and flowed down the vale of york, being augmented on its way by tributary glaciers coming down wensleydale. the final melting seems to have taken place somewhere a little to the southward of york; but boulders of shap granite by which its extension is characterised have been found as far to the southward as royston, near barnsley. "the other branch of the solway glacier--that which travelled due eastward--passed up the valley of the irthing, and over into that of the tyne, and out to sea at tynemouth. it carried the scottish granites with it, and tributary masses joined on either hand, bringing characteristic boulders with them. "the fate of those elements of the solway frith glacier which reached the sea is not left entirely to conjecture. the striated surfaces near the coast of northumberland indicate a coastwise flow of ice from the northward--probably from the frith of forth--and the glaciers coming out from the tyne and tees were deflected to the southward. "there is conclusive evidence that this ice rasped the cliffs of the yorkshire coast and pressed up into some of the valleys. where it passed the mouth of the tees near whitby it must have had a height of at least feet, but farther down the coast it diminished in thickness. it nowhere extended inland more than a mile or two, and for the most part kept strictly to the coast-line. along the whole coast are scattered erratics derived from galloway and the places lying in the paths of the glaciers. in many places the cliffs exhibit signs of rough usage, the rocks being crumpled and distorted by the violent impact of the ice. at filey brigg a well-scratched surface has been discovered, the striation being from a few degrees east of north. "at speeton the evidence of ice-sheet or glacier-work is of the most striking character. on the top of the cliffs of cretaceous strata a line of moraine-hills has been laid down, extending in wonderful perfection for a distance of six miles. they consist of a mixture of sand, gravel, and a species of clay-rubble, with occasional masses of true boulder-clay, the whole showing the arched bedding so characteristic of such accumulations. at the northerly end the moraine keeps close to the edge of the chalk cliffs, which are there feet high, and the hills are frequently displayed in section; but as the elevation of the cliffs declines they fall back from the edge of the cliffs and run quite across the headland of flamborough, and are again exposed in section in bridlington bay. one remarkable and significant fact is pointed out, namely, that behind this moraine, within half a mile and at a lower level, the country is almost absolutely devoid of any drift whatever. [illustration: fig. .--moraine between speeton and flamborough (lamplugh).] "the interpretation of these phenomena is as follows: when the valley-glaciers reached the sea they suffered the deflection which has been mentioned, partly as the result of the interference of ice from the east of scotland, but also influenced directly by the cause which operated upon the scottish ice and gave direction to it--that is, the impact of a great glacier from scandinavia, which almost filled the north sea, and turned in the eastward-flowing ice upon the british coast. "it is easy to see how this pressure must have forced the glacier-ice against the yorkshire coast, but vertical chalk cliffs feet in height are not readily surmounted by ice of any thickness, however great, and so it coasted along and discharged its lateral moraine upon the cliff-tops. as the cliffs diminished in height we find the moraine farther inland, and, as i have pointed out, the ice completely overrode flamborough head. amongst the boulders at flamborough are many of shap granite, a few galloway granites, a profusion of carboniferous rocks, brought by the tyne branch of the sol way glacier as well as by that of stainmoor, and, besides many torn from the cliffs of yorkshire, a few examples of unquestionable scandinavian rocks, such as the well-known _rhomben-porphyr_. it is important to note that about ten to twenty miles from the yorkshire coast there is a tract of sea-bottom called by trawlers 'the rough ground,' in allusion to the fact that it is strewn with large boulders, amongst which are many of shap granite. this probably represents a moraine of the teesdale glacier, laid down at a time when the scandinavian glacier was not at its greatest development. "on the south side of flamborough head the 'buried cliff' previously alluded to occurs. the configuration of the country shows--and the conclusion is established by numerous deep-borings--that the preglacial coast-line takes a great sweep inland from here, and that the plain of holderness is the result of the banking-up of an immense thickness of glacial _débris_. in the whole country reviewed, from tynemouth to bridlington, wherever the ice came on to the land from the seaward, it brought in shells and fragmentary patches of the sea-bottom involved in its ground moraine. space does not permit of a detailed description of the several members of the yorkshire drift, and i pass on to deal in a general way with the glacial phenomena of the eastern side of england. "_the east anglian glacier._--the influence of the scandinavian ice is clearly seen in the fact that the entire ice-movement down the east coast south of bridlington was all from the _seaward_. clays, sands, and gravels, the products of a continuous mass of land-ice coming from the northeast are spread over the whole country, from the trent to the high grounds on the north of london overlooking the thames. "the line of extreme extension of these drift-deposits runs from finchley (near london), in the south across hertfordshire, through cambridgeshire, with outlying patches at gogmagog and near buckingham, and northwestward over a large portion of leicestershire into the upper waters of the trent, embracing the elevated region of palæozoic rocks at charnwood forest, near leicester. "reserving the consideration of the very involved questions connected with the drifts of the upper part of the trent valley, i may pass on to join the phenomena of the southeastern counties with those at flamborough head. from nottinghamshire the limits of the drift of the east anglian glacier seem to run in a direction nearly due west to east, for the great oolitic escarpment upon which lincoln cathedral is built is absolutely driftless to the northward of the breach about sleaford. however, along the western flank of the oolitic range true boulder-clay occurs, bordering and doubtless underlying the great fen-tract of mid-lincolnshire; and the great lincolnshire wolds appear to have been completely whelmed beneath the ice. "the most remarkable of the deposits in this area is the great chalky boulder-clay, which consists of clay containing much ground-up chalk, and literally packed with well-striated boulders of chalk of all sizes, from minute pebbles up to blocks a foot or more in diameter. associated with them are boulders of various foreign rocks, and many flints in a remarkably fresh condition, and still retaining the characteristic white coat, except where partially removed by glacial attrition. "one of the perplexing features of the glacial phenomena in the eastern counties of england is the extension of true chalky boulder-clay to the north london heights at finchley and elsewhere; for only the faintest traces are to be found in the gravel deposits of the thames valley of any wash from such a deposit, or from a glacier carrying such materials. "it has been suggested that the deposit may have been laid down in an extra-morainic lake, or in an extension of the north. sea, but these suggestions leave the difficulty just where it was. if a lake or sea could exist without shores, a glacier-stream might equally dispense with banks. within the area of glaciation, defined above, abundant evidence of the action of land-ice is obtainable, though striated surfaces are extremely rare--a fact attributable to the softness of the chalk and clays which occupy almost the whole area. well-striated surfaces are found on the harder rocks, as, for example, on the oolitic limestone at dunston, near lincoln. "mr. skertchly has remarked that the proofs of the action of land-ice are irrefragable. the great chalky boulder-clay covers an area of , square miles, and attains an altitude of feet above the sea-level, thus bespeaking, if the product of icebergs, 'an extensive gathering-ground of chalk, having an elevation of more than feet. but where is it? certainly not in western europe, for the chalk does not attain so great an elevation except in a few isolated spots.'[br] [footnote br: geikie's great ice age, p. .] [illustration: fig. .--diagram-section near cromer (woodward). . gravel and sand (middle glacial) resting on contorted drift (loam, sand, and marl, with large included boulders of chalk); . cromer till: . laminated clay and sands (leda myalis bed); . fresh-water loams and sands: _a_. black fresh-water bed of runton (upper fresh-water bed); . forest bed--laminated clays and sands, with roots and _débris_ of wood, bones of mammalia, estuarine mollusca, etc., the upper part in places penetrated by rootlets (rootlet bed); _a_. weybourn crag; . chalk with flints; * large included boulder of chalk.] "it has been further pointed out by mr. skertchly, that the condition of the flints in this deposit furnishes strong evidence that they could not have been carried by floating ice nor upon a glacier, for, in either of the latter events, there must have been some exposure to the weather, which, as he remarks, would have rendered them worthless to the makers of gun-flints, whereas they are now regularly collected for their use. "the way in which the boulder-clay is related to the rocks upon which it rests is a conclusive condemnation of any theory of floating ice; for example, where it rests upon oxford clay, it contains the fossils characteristic of that formation, as it is largely made up of the clay itself. the exceptions to this rule are as suggestive as those cases which conform to it. each outcrop yields material to the boulder-clay to the south westward, showing a pull-over from the northeast. "one of the most remarkable features of the drift of this part of england is the inclusion of gigantic masses of rock transported for a short distance from their native outcrop, very often with so small a disturbance that they have been mapped as _in situ_. examples of chalk-masses feet in length, and of considerable breadth and thickness, have been observed in the cliffs near cromer, in norfolk, but they are by no means restricted to situations near the coast. one example is mentioned in which quarrying operations had been carried on for some years before any suspicion was aroused that it was merely an erratic. the huge boulders were probably dislodged from the parent rock by the thrust of a great glacier, which first crumbled the beds, then sheared off a prominent fold and carried it along. this explanation we owe to mr. clement reid.[bs] the drift-deposits of this region frequently contain shells, but they rarely constitute what may be termed a consistent fauna, usually showing such an association as could only be found where some agent had been at work gathering together shells of different habitats and geological age. [footnote bs: see geology of the country around cromer, and geology of holderness, memoirs of geological survey of england and wales.] [illustration: fig. .--section at right angles to the cliff through the westerly chalk bluff at trimingham, norfolk, showing the manner in which chalk masses are incorporated into the till (clement reid). scale, fret to an inch. a. level of low-water spring-tides; b. chalk, with sandy bed at *; c. forest-bed series, etc., seen in the cliffs a few yards north and south of this point; d. cromer till, stiff lead-colored boulder-clay; e. fine, chalky sands, much false-bedded; f. contorted drift, brown bouldery-clay with marked bedding- or fluxion-structure; g. the bed, above the white line were seen and measured by more snow and measured by mr. reid; * chalk seen _in situ_ on beach. "if the ice-sheet, instead of flowing over the beds, happens to plough into them or abut against them, it would bend up a boss of chalk, as at beeston. a more extensive disturbance, like that at trimingham drives before it a long ridge of the bads, and nips up the chalk, till, like a cloth creased by the sliding of a heavy book, it is folded into an inverted anticlinal. a slight increase of pressure, and the third stage is reached--the top of the anticlinal being entirely sheared off, the chalk boulder driven up an incline, and forced into the overlying boulder-clays." (clement reid.)] "attempts have been made to correlate the deposits over the whole area, but with very indifferent success. a consideration of the consequences of the invasion of the country by an ice-stream from the northeast will prepare us for any conceivable complication of the deposits. "the main movement was against the drainage of the country, so that the ice-front must have been frequently in water. there would be aqueous deposition and erosion; the kneading up of morainic matter into ground-moraine; irregularities of distribution and deposition due to ice floating in an extra-morainic lake; flood-washes at different points of overflow; and other confusing causes, which make it rather matter for surprise that any order whatever is traceable. "i now turn to the valley of the trent. we find that it occupies such a position that it would be exposed, successively or simultaneously, to the action of ice-streams of most diverse origin. i have shown that the area to the westward of lichfield was invaded at one period by a welsh glacier, and at a subsequent one by the irish sea glacier, and both of these streams entered the valley of the trent or some of its affluents. from the eastward, again, the great north sea glacier encroached in like manner, carrying the great chalky boulder-clay even into the drainage area of the westward-flowing rivers near coventry. "the glacial geology of the trent valley from burton to nottingham has been ably dealt with by mr. r. m. deeley,[bt] who recognises a succession which may be generalised as follows: ( .) a lower series containing rocks derived from the pennine chain; ( .) a middle series containing rocks from the eastward (chalky boulder-clay, etc.); and ( .) an upper series with pennine rocks. mr. deeley thinks the pennine _débris_ may have been brought by glaciers flowing down the valleys of the dove, the wye, and the derwent; but, while recognising the importance of the testimony adduced, especially that of the boulders, i am compelled to reserve judgment upon this point until something like moraines or other evidences of local glaciers can be shown in those valleys. in their upper parts there is not a sign of glaciation. some of the deposits described must have been laid down by land-ice; while the conformation of the country shows that during some stages of glaciation a lake must have existed into which the different elements of the converging glaciers must have projected. this condition will account for the remarkable commingling of boulders observed in some of the deposits. welsh, cumbrian, and scottish rocks occur in the western portion of the trent valley. the overflow of the extra-morainic lake would find its way into the valleys of the avon and severn, and may be taken to account for the abundance of flints in some of the gravels. [footnote bt: quarterly journal geological society, vol. xlii, p. .] "_the isle of man._--this little island in mid-seas constituted in the early stages of the glacial epoch an independent centre of glaciation, and from some of its valleys ice-streams undoubtedly descended to the sea; but with the growth of the great irish sea glacier the native ice was merged in the invading mass, and at the climax of the period the whole island was completely buried, even to its highest peak (snae fell, , feet), beneath the ice. the effects of this general glaciation are clearly seen in the mantle of unstratified drift material which overspread the hills; in the _moutonnée_ appearance of the entire island; and in the transport of boulders of local rocks. the striations upon rock surfaces show a constancy of direction in agreement with the boulder-transport which can be ascribed to no other agency than a great continuous sheet of such dimensions as to ignore minor hills and valleys. "the disposition of the striæ is equally conclusive, for we find that on a stepped escarpment of limestone both the horizontal and the vertical faces are striated continuously and obliquely from the one on to the other, showing that the ice had a power of accommodating itself to the surface over which it passed that could not be displayed by floating ice. there is a remarkable fact concerning the distribution of boulders on this island which would strike the most superficial observers, namely, that foreign rocks are confined to the low grounds. it might be argued that the local ice always retained its individuality, and so kept the foreign ice with its characteristic boulders at bay. but, apart from the _a priori_ improbability of so small a hill-cluster achieving what the lake district could not accomplish, the fact that snae fell, an isolated _conical_ hill, is swathed in drift from top to bottom, is quite conclusive that the foreign ice must have got in. why, then, did it carry no stones with it? the following suggestion i make not without misgivings, though there are many facts to which i might appeal that seem strongly corroborative: "the hilly axis of the island runs in a general northeast and southwest direction, and it rises from a great expanse of drift in the north with singular abruptness, some of the hills being almost inaccessible to a direct approach without actual climbing. i imagine that the ice which bore down upon the northern end of the island was, so far as its lower strata were concerned, unable to ascend so steep an acclivity, and was cleft, and flowed to right and left. the upper ice, being of ice-sheet origin, would be relatively clean, and this flowing straight over the top of the obstruction would glaciate the country with such material as was lying loose upon the ground or could be dislodged by mere pressure. it would appear from published descriptions that the isle of arran offers the same problem, and i would suggest the application of the same solution to it. "marine shells occur in the manx drift, but only in such situations as were reached by the ice-laden with foreign stones. they present similar features of association of shells of different habitat, and perhaps of geological age, to those already referred to as being common characteristics of the shell-faunas of the drift of the mainland. four extinct species of mollusca have been recognised by me in the manx drift. "the manx drift is of great interest as showing, perhaps better than any locality yet studied, those features of the distribution of boulders of native rocks which attest so clearly the exclusive action of land-ice. there are in the island many highly characteristic igneous rocks, and i have found that boulders of these rocks never occur to the northward of the parent mass, and very rarely in any direction except to the southwest. "cumming observed in regard to one rock, the foxdale granite, that whereas the highest point at which it occurs _in situ_ was feet above sea-level, boulders of it occurred in profusion within feet of the summit of south barrule ( , feet), a hill two miles only, in a southwesterly direction, from the granite outcrop. "they also occur on the summit of cronk-na-irrey-lhaa, , feet above sea-level. the vertical uplift has been and feet respectively. "in the low grounds of the north of the island a finely developed terminal moraine extends in a great sweep so as to obstruct the drainage and convert thousands of acres of land into lake and morass, which is only now yielding to artificial drainage. many fine examples of drumlin and esker mounds occur at low levels in different parts of the island; and it was remarked nearly fifty years ago by cumming, that their long axes were parallel to the direction of ice-movement indicated by the striated surfaces and the transport of boulders. "the foreign boulders are mainly from the granite mountains of galloway, but there are many flints, presumably from antrim, a very small number of lake district rocks, and a remarkable rock containing the excessively rare variety of hornblende, riebeckite. this has now been identified with a rock on ailsa crag, a tiny islet in the frith of clyde; and a manx geologist, the rev. s. n. harrison, has discovered a single boulder of the highly characteristic pitchstone of corriegills, in the isle of arran. "_the so-called great submergence._ "it may be convenient to adduce some additional facts which render the theory of a great submergence of the country south of the cheviots untenable. "the sole evidence upon which it rests is the occurrence of shells, mostly in an extremely fragmentary condition, in deposits occurring at various levels up to about , feet above sea-level: a little space may profitably be devoted to a criticism of this evidence. "_moel tryfaen_ ('the hill of the three rocks').--this celebrated locality is on the first rise of the ground between the menai straits and the congeries of hills constituting 'snowdonia'; and when we look to the northward from the top of the hill ( , feet) we see the ground rising from the straits in a series of gentle undulations whose smooth contours would be found from a walk across the country to be due to the thick mask of glacial deposits which obliterates the harsher features of the solid rocks. "the deposits on moel tryfaen are exposed in a slate-quarry on the northern aspect of the hill near the summit, and consist of two wedges of structureless boulder-clay, each thinning towards the top of the hill. the lower mass of clay, wherever it rests upon the rock, contains streaks and irregular patches of eccentric form, of sharp, perfectly angular fragments of slate; and the underlying rock may be seen to be crushed and broken, its cleavage-laminæ being thrust over from northwest to southeast--that is, _up-hill_. the famous 'shell-bed' is a thick series of sands and gravels interosculated with the clays on the slope of the hill, but occupying the entire section above the slate towards the top. the bedding shows unmistakable signs of the action of water, both regular stratification and false bedding being well displayed. the stones occurring in the clays are mainly if not entirely welsh, including some from the interior of the country, and they are not infrequently of large size--two or three tons' weight--and well scratched. "the stones found in the sands and gravels include a great majority of local rocks, but besides these there have been recorded the following: rock. source. highest minimum point uplift _in situ_. in feet. granite eskdale, cumberland , granite criffel, galloway ..... ... flint antrim (?) , to these i can add: granophyre buttermere, cumberland ..... ... eurite [bu] ailsa craig, frith of clyde , [footnote bu: the altitude at which this rock occurs on ailsa craig has not been announced, so have put it as the extreme height of the island.] "the shells in the moel tryfaen deposit have been fully described, so far as the enumeration of species and relative frequency are concerned, but little has been said as to their absolute abundance and their condition. the shells are extremely rare, and daring a recent visit a party of five persons, in an assiduous search of about two hours, succeeded in finding _five whole shells_ and about two ounces of fragments. the opportunities for collecting are as good as could be desired. the sections exposed have an aggregate length of about a quarter of a mile, with a height varying from ten to twenty feet of the shelly portion; and besides this there are immense spoil-banks, upon whose rain-washed slopes fossil-collecting can be carried on under the most favorable conditions. "i would here remark, that the occurrence of small seams of shelly material of exceptional richness has impressed collectors with the idea that they were dealing with a veritable shell-bed, when the facts would bear a very different interpretation. a fictitious abundance is brought about by a process of what may be termed 'concentration,' by the action of a gently flowing current of water upon materials of different sizes and different specific gravities. shells when but recently vacated consist of materials of rather high specific gravity, penetrated by pores containing animal matter, so that the density of the whole mass is far below that of rocks in general, and hence a current too feeble to move pebbles would yet carry shells. illustrations of this process may be observed upon any shore in the concentration of fragments of coal, corks, or other light material. "regarding the interpretation of these facts: the commonly received idea is, that the beds were laid down in the sea during a period of submergence, and that the shells lived, not perhaps on the spot, but somewhere near, and that the terminal curvature of the slate was produced by the grounding of icebergs which also brought the boulders. but if this hypothesis were accepted, it would be necessary to invest the flotation of ice with a constancy of direction entirely at variance with observed facts, for the phenomena of terminal curvature is shown" with perfect persistence of direction wherever the boulder-clay rests upon the rock; and, further, there is the highly significant fact, that neither the sands and gravels nor the rock upon which they rest show any signs of disturbance or contortion, such as must have been produced if floating ice had been an operative agent. "the uplift of foreign rocks is equally significant; and when we take into account the great distances from which they have been borne and the frequency with which such an operation must have been repeated, the inadequacy becomes apparent of darwin's ingenious suggestion, that it might have been effected by a succession of uplifts by shore-ice during a period of slow subsidence; while the character and abundance of the molluscan remains invest with a species of irony the application of the term 'shell-bed' to the deposit. "i now turn to the alternative explanation (see _ante_, p. ), viz., that the whole of the phenomena were produced by a mass of land-ice which was forced in upon moel tryfaen from the north or northwest, overpowering any welsh ice which obstructed its course. this view is in harmony with the observations regarding the 'terminal curvature' of the slates, the occurrence of sharp angular chips of slate in the boulder-clay, and the coincidence of direction of these indications of movement with the carry of foreign stones. the few shells and shell-crumbs in the sands and gravels would, upon this hypothesis, be the infinitesimal relics of huge shell-banks in the irish sea which were destroyed by the glacier and in part incorporated in its ground-moraine or involved in the ice itself. the sands and gravels would represent the wash which would take place wherever, by the occurrence of a 'nunatak' or by approach to the edge of the ice, water could have a free escape. "two principal objections have been urged to the land-ice explanation of the moel tryfaen deposits. an able critic asks, 'can, then, ice walk up-hill?' to this we answer, given a sufficient 'head' behind it, and ice can certainly achieve that feat, as every _roche moutonnée_ proves. if it be granted that ice on the small scale can move up-hill, there is no logical halting-place between the uplift of ten or twenty feet to surmount a _roche moutonnée_, and an equally gradual elevation to the height of moel tryfaen. furthermore, the inland ice of greenland is known to extrude its ground-moraine on the 'weather-side' of the nunataks, and the same action would account for the material uplifted on moel tryfaen. "the second objection brought forward was couched in somewhat these terms: 'if the lake district had its ice-sheet, surely wales had one also. could not snowdonia protect the heart of its own domain?' of course, wales had its ice-sheet, and the question so pointedly raised by the objector needs an answer; and though it is merely a question of how much force is requisite to overcome a certain resistance (both factors being unknown), still there are features in the case which render it specially interesting and at the same time comparatively easy of explanation. it seems rather like stating a paradox, yet the fact is, that it was the proximity of snowdon which, in my opinion, enabled the foreign ice to invade wales at that point. "a glance at the map will show that the 'radiant point' of the welsh ice was situated on or near arenig mawr, and that the great mass of snowdon stands quite on the periphery of the mountainous regions of north wales, so that it would oppose its bulk to fend off the native ice-sheet and prevent it from extending seaward in that direction. [illustration: fig. .--section across wales to show the relationship of native to foreign ice.] "as a consequence, the only welsh ice in position to obstruct the onward march of the invader would be such trifling valley-glaciers as could form on the western slopes of snowdon itself. "the peak of snowdon is , feet above sea-level, and arenig mawr, , feet high, is eighteen miles to the eastward, and a broad, deep valley with unobstructed access to cardigan bay intervenes; so, if any ice from the central mass made its way over the snowdonian range, it performed a much more surprising feat than that involved in the ascent of moel tryfaen from the westward. "the profile shows in diagrammatic form the probable relations of the foreign to the native ice at the time when the moel tryfaen deposits were laid down. "from what has been said regarding the great glaciers, it would seem that ice advanced upon the land from the seaward in several parts of the coast of england, wales, and the isle of man. now, it is in precisely those parts of the country, and those alone, that the remains of marine animals occur in the glacial deposits. if the dispersal of the shells found in the drift had been effected by the means i have suggested, it would follow, as an inevitable consequence, that wherever shells occur there should also be boulders which have been brought from beyond the sea. this i find to be the case, and in two instances the discovery of shells was preliminary to the extension of the boundaries of the known distribution of boulders of trans-marine origin. "the officers of the geological survey some years ago observed the occurrence of 'obscure fragments of marine shells' in a deposit at whalley, lancashire, in which they could find only local rocks. one case such as this would be fatal to the theory of the _remanié_ origin of the shells, but on visiting the section with mr. w. a. downham, i found, amongst the very few stones which occurred in the shell-bearing sand at the spot indicated, two well-marked examples of cumbrian volcanic rocks, and, at a little distance, large boulders of scottish granites. "the second case is more striking. the announcement was made that shells had been found on a hill called gloppa near oswestry, in shropshire, and, as it lay about five miles to the westward of mackintosh's boundary of the irish sea glacier, and therefore well within the area of exclusively welsh boulders, it furnished an excellent opportunity of putting the theory to the test. an examination of the boulders associated with the shells showed that the whole suite of galloway and cumbrian erratics such as belong to the irish sea glacier were present in great abundance. not only this, but in the midst of the series of shell-bearing gravels i observed a thin lenticular bed of greenish clay, which upon examination was found to be crowded with well-scratched specimens of welsh rocks; but neither a morsel of shell nor a single pebble of a foreign rock could be found, either by a careful examination in the field or by washing the clay at home, and examining with a lens the sand and stones separated out. "the fact that predictions such as these have been verified affords a very striking corroboration of the theory put forward; and, though shells cannot be found in every deposit in which they might, _ex hypothesi_, be found, yet the strict limitation of them to situations which conform to those assigned upon theoretical grounds cannot be ascribed to mere coincidence. if the land had ever been submerged during any part of the glacial epoch to a depth of , feet, it is inconceivable that clear and indisputable evidence should not be found in abundance in the sheltered valleys of the lake district and wales, which would have been deep, quiet fiords, in which vast colonies of marine creatures would have found harbour, as they do in the deep lochs of scotland to-day. "it has been urged, in explanation of this absence of marine remains in the great hill-centres, that the 'second glaciation' might have destroyed them; but to do this would require that the ice should make a clean and complete sweep of all the loose deposits both in the hollows of the valleys and on the hill-sides, and further that it should destroy all the shells and all the foreign stones which floated in during the submergence. at the same time we should have to suppose that the drift which lay in the paths of the great glaciers was not subjected to any interference whatever. but, assuming that these difficulties were explained, there would still remain the fact that the valleys which have never been glaciated--as, for example, those of derbyshire--show no signs whatever of any marine deposits, nor of marine action in any form whatever. "the sea leaves other traces also, besides shells, of its presence in districts that have really been submerged, yet there are no signs whatever to be found of them in all england, except the _post_-glacial raised beaches. furthermore, in all the area occupied by glacial deposits there are no true sea-beaches, no cliffs nor sea-worn caves, no barnacle-encrusted rocks, nor rocks bored by pholas or saxicava. are we to believe that these never existed; or that, having existed, they have been obliterated by subsequent denudations? to make good the former proposition, it would be necessary as a preliminary to show that the movement of subsidence and re-elevation was so rapid, and the interval between so brief, that no time was allowed for any marine erosion to take place. if this were so, it would be the most stupendous catastrophe of which we have any geological record; but we are not left in doubt regarding the duration of the submerged condition, for the occurrence of forty feet of gravel upon the summits of the hills indicates plainly that, if they were accumulated by the sea, the land must have stood at that level for a very long period, amply sufficient for the formation of a well-marked coast-line. "the alternative proposition, that post-glacial denudation had removed the traces of subsidence, is equally at variance with the evidence. post-glacial denudation has left kames and drumlins, and all the other forms of glacial deposits, in almost perfect integrity; the small kettle-holes are not yet filled up; and it is therefore quite out of the question that the far more enduring features, such as sea-cliffs, shore platforms, and beaches, should have been destroyed. "the only reasonable conclusion is, that these evidences of marine action never existed, because the land in glacial times was never depressed below its present level. if the level were different at all (as i think may have been the case on the western side of england), it was higher, and not lower. "the details of the submergence hypothesis have, so far as i am aware, never been dealt with by its advocates, otherwise i cannot but think that it would have been abandoned long since. it has been stated in general terms that the subsidence was greatest in the north and diminished to zero in the south, but no attempt was made to trace the evidence of extreme subsidence across country and along the principal hill-ranges--in fact, to see how it varied in every direction. "if we take a traverse of england, say from flamborough head upon the east to moel tryfaen on the west, and accept as evidence of submergence any true glacial deposits (except, as in the case of the interior of wales, the deposits are obviously the effects of purely local glaciers and contain, therefore, no shells), we shall find that the subsidence, if any, must have been not simply differential but sporadic. [illustration: fig. .--section of the cliff on the east side of south sea landing, flamborough head. scale, feet to inch; length of section yards; average height, feet. (see above map of moraine between speeton and flamborough.) explanation.--_ ._ brownish boulder-clay, a band of pebbles; _ a_, in places about seven feet from top. _ ._ washed gravel, with thin sand-seams, well-bedded, pebbles chiefly erratics. _ ._ "basement" boulder-clay, with many included patches of sand, gravel, and silt; _ a_, at _b_, one of these _ b_ contain shells. _ b_. sand and silt, overlying and in places interbedded with _ _. _ ._ rubble of angular and subangular chalk-blocks and gravel, with occasional erratic, passes partly into chalky boulder-clay, _ a_. _x_. white chalk, without flints, surface much shaken.] "at flamborough head shelly drift attains an altitude of feet, but half a mile from the coast the country is practically driftless even at lower levels. the yorkshire wolds were not submerged. on the western flanks of the wolds drift comes in at about to feet, and persists, probably, under the post-glacial warp, from which it again protrudes on the western side of the valley of the ouse, and however the drift between there and the pennine water-shed may be interpreted, it shows not a sign of marine origin; but, even granting that it did, we find that it does not reach within a thousand feet of the water-shed. when the water-shed is crossed, however, abundant glacial deposits are met with which are not to be differentiated from others at slightly lower levels which contain shells. [illustration: fig. .--enlarged section of the shelly sand and surrounding clay at _b_ in preceding figure. scale, feet to inch. explanation.--_ ._ "basement" boulder-clay. _ a_. pure compact blue and brown clay of aqueous origin, bedding contorted and nearly obliterated, but the mass is cut up by shearing planes. _ b_. irregular seam, and scattered streaks, of greenish-yellow sand with many marine shells. _ c_. patch of pale-yellow sand, different from _ b_, without trace of fossils.] "if we suppose that the line of our traverse crosses the pennine chain at heald moor, we shall find that on the eastern side no traces of drift occur above about feet; while the very summit of the water-shed is occupied by boulder-clay, and thence downward the trace is practically continuous, and at about , feet and downward the drift contains marine shells. across the great plain of lancashire and cheshire the 'marine' drift is fully developed--though it may be remarked in parentheses that it contains a shallow-water fauna, albeit _ex hypothesi_ deposited, in part at least, in a depth of fathoms of water--and to the welsh border at frondeg, where it again reaches a water-shed at an altitude of , feet; but at yards to the westward of the summit all traces of subsidence disappear, and through the centre of wales no sign is visible; then we emerge on the western slopes at moel tryfaen, and they assume their fullest dimensions, though only to finish abruptly on the hill-top, and put in no appearance in the lower grounds which extend from there to the sea. "the conclusions pointed to by the evidence (and, as i have endeavoured to show, all the evidence which existed at the close of the glacial period is there still) are, that a subsidence of the yorkshire wolds took place on the east, but not in the centre or west; that the pennine chain was submerged on the western side to a depth of , feet, and on the east to not more than feet, even on opposite sides of the same individual hill; that all the lowlands between, say, bacup and the welsh border, were submerged, and that the hills near frondeg partook of this movement, but only on their eastern sides; that the centre of wales was exempt, but that the summit of moel tryfaen forms an isolated spot submerged, while the surrounding country escaped. these absurdities might be indefinitely multiplied, and they must follow unless it be admitted that the phenomena are the results of glacial ice, and that ice can move 'up-hill.' "the south of england certainly has partaken of no movement of subsidence. a line drawn from bristol to london will leave all the true glacial deposits to the northward, except a bed of very questionable boulder-clay at watchet, and a peculiar deposit of clayey rubble which has been produced on the flanks of the cornish hills probably, as the late s. v. wood, jr, suggested, by the slipping of material over a permanently frozen subsoil. "for the remainder of the southern area the evidence is plain that there has been no considerable subsidence during glacial times. the presence over large areas of chalk country of the 'clay with flints'--a deposit produced by the gradual solution of the chalk and the accumulation in situ of its insoluble residue--is absolute demonstration that for immense periods of time the country has been exempt from any considerable aqueous action. the enormous accumulations of china clay upon the granite bosses of cornwall and devon tell the same tale. a few erratics have been found at low levels at various points on the southern coasts, usually not above the reach of the waves. these consist of rocks which may have been floated by shore-ice from the channel islands or the french coast. "this imperfect survey of the evidence against the supposed submergence has been rendered the more difficult by the fact that it is not considered necessary to produce the evidence of marine shells in all cases. indeed, it has been argued that post-tertiary beds covering thousands of square miles might be absolutely destitute of shells without prejudice to the theory of their formation in the sea. "but such a suggestion, one would think, could hardly come from anyone familiar with marine tertiary deposits, or even with the appearance of modern sea-beaches. admitting, however, for the purposes of argument, that the beaches along a great extent of coast might be devoid of shells, it cannot be argued that the deep waters were destitute of life; and hence the boulder-clays, if of marine origin, should contain a great abundance of shells and other remains, and, once entombed, it is beyond belief that they could all be removed from such a deposit in the short lapse of post-glacial time. "now, some of the boulder-clays--as, for example, those of lancashire and cheshire--are held to be of marine origin, and this is indeed a vital necessity to the submergence theory; for, if these are not marine deposits, neither are the other shelly deposits; but these boulder-clays are absolutely indistinguishable from those lying within the hill-centres, and, as it passes belief that such deposits could be of diverse origin and yet possess an identical structure and arrangement, then we should have a right to demand that these clays should have enclosed shells and should still contain them, but they do not. "i may here mention that i am informed by mr. w. shone, f. g. s.--and he was good enough to permit me to quote the statement--that the boulder-clay of cheshire and the shelly boulder-clay of caithness are 'as like as two peas.' the importance of this comparison lies in the fact that, since croll's classical description, all observers have agreed that it was the product of land-ice which moved in upon the land out of the dornoch firth. it was pointed out then, as since has been done for england, that it was only where the direction of ice-movement was from the seaward that any shells occur in the boulder-clay. "_the dispersion of erratics of shap granite._--so great a significance attaches to the peculiar distribution of this remarkable rock, that i may add a few details here which could not be conveniently introduced elsewhere. "this granite occupies an area which lies just to the northward of the water-shed between the basins of the lime and the eden, and its extreme elevation is , feet. boulders occur in large numbers as far to the northward as cross fells, while, as already described, they pass over stainmoor and are dispersed in great numbers along the route taken by the great stainmoor branch of the solway glacier. but a considerable number of the boulders also found their way to the southward, and a well-marked trail can be followed down into morecambe bay; and at hest bank, to the north of lancaster, the boulder-clay contains many examples, together with the 'mica-trap' of the kendal and sedbergh dykes and other local rocks, but no shells or erratics from other sources than the country draining into morecambe bay. to the southward the ice which bore these rocks was deflected by the great irish sea glacier, and, so far as present information enables me to state, the shap granite blocks mark the course of the medial moraine between these two ice-streams. it has been found near garstang, at longridge, and at whalley, this being the exact line of junction of the irish sea glacier with the ice from morecambe bay and the pennine chain. "it is a very remarkable and significant fact, that not a single authentic occurrence of the rock across the boundary indicated has yet been recorded." _northern europe._ on passing over the shallow german sea from england to the continent, the southern border of the scandinavian ice-field is found south of the zuyder zee, between utrecht and arnhem--the moraine hills in the vicinity of arnhem being quite marked, and a barren, sandy plain dotted with boulders and irregular moraine hills extending most of the way to the zuyder zee. from arnhem the southern boundary of the great ice-field runs "eastward across the rhine valley, along the base of the westphalian hills, around the projecting promontory of the hartz, and then southward through saxony to the roots of the erzgebirge. passing next southeastward along the flanks of the riesen and sudeten chain, it sweeps across poland into russia, circling round by kiev, and northward by nijni-novgorod towards the urals."[bv] thence the boundary passes northward to the arctic ocean, a little east of the white sea. [footnote bv: a. geikie's text-book of geology, p. .] the depth of this northern ice-sheet is proved to have been upwards of , feet where it met the hartz mountains, for it has deposited northern _débris_ upon them to that height; while, as already shown, it must have been over , feet in the main valley of switzerland. in norway it is estimated that the ice was between , and , feet thick. the amount of work done by the continental glaciers of europe in the erosion, transportation, and deposition of rock and earthy material is immense. according to helland, the average depth of the glacial deposits over north germany and northwestern russia is german feet, i. e., about english feet. as the deposition towards the margin of a glacier must be commensurate with its erosion near the centre of movement, this vast amount implies a still greater proportionate waste in the mountains of scandinavia, where the area diminishes with every contraction of the circle. two hundred and fifty feet is therefore not an extravagant calculation for the amount of glacial erosion in the scandinavian peninsula. it is not difficult to see how the scandinavian mountains were able to contribute so much soil to the plains of northern germany and northwestern russia. previous to the glacial period, a warm climate extended so far north as to permit the growth of semi-tropical vegetation in spitsbergen, greenland, and the northern shores of british america. such a climate, with its abundant moisture and vegetation, afforded most favourable conditions for the superficial disintegration of the rocks. when, therefore, the cold of the glacial period came on, the moving currents of ice would have a comparatively easy task in stripping the mantle of soil from the hills of norway and sweden, and transporting it towards the periphery of its movement. of course, erosion in scandinavia meant subglacial deposition beyond the baltic. doubtless, therefore, the plains of northern germany, with their great depth of soil, are true glacial deposits, whose inequalities of surface have since been much obliterated, through the general influences of the lapse of time, and by the ceaseless activity of man. an interesting series of moraines in the north of germany, bordering the baltic sea, was discovered in by professor salisbury, of the united states geological survey. its course lies through schleswig-holstein, mecklenburg, potsdam (about forty miles north of berlin), thence swinging more to the north, and following nearly the line between pomerania and west prussia, crossing the vistula about twenty miles south of dantzic, thence easterly to the spirding see, near the boundary of poland. among the places where this moraine can be best seen are--" . in province holstein, the region about (especially north of) eutin; . province mecklenburg, north of crivitz, and between bütow and kröpelin; . province brandenburg, south of reckatel, between strassen and bärenbusch, south of fürstenberg and north of everswalde, and between pyritz and solden; . province posen, east of locknitz, and at numerous points to the south, and especially about falkenburg, and between lompelburg and bärwalde. this is one of the best localities. . province west preussen, east of bütow; . province ost preussen, between horn and widikin." comparing these with the moraines of america, professor salisbury remarks: "in its composition from several members, in its variety of development, in its topographic relations, in its topography, in its constitution, in its associated deposits, and in its wide separation from the outermost drift limit, this morainic belt corresponds to the extensive morainic belt of america, which extends from dakota to the atlantic ocean. that the one formation corresponds to the other does not admit of doubt. in all essential characteristics they are identical in character. what may be their relations in time remains to be determined." [illustration: fig. .--map showing the glaciated area of europe according to j. geikie, and the moraines in britain and germany according to lewis and salisbury.] the physical geography of europe is so different from that of america, that there was a marked difference in the secondary or incidental effects of the glacial period upon the two regions. in america the continental area over which the glaciers spread is comparatively simple in its outlines. east of the rocky mountains, as we have seen, the drainage of the glacial period was, for a time, nearly all concentrated in the mississippi basin, and the streams had a free course southward. but in europe there was no free drainage to the south, except over a small portion of the glaciated area in central russia, about the head-waters of the dnieper, the don, and the volga; though the danube and the rhône afforded free course for the waters of a portion of the great alpine glaciers. but all the great rivers of northern europe flow to the northward, and, with the exception of the seine, they all for a time encountered the front of the continental ice-sheet. this circumstance makes it difficult to distinguish closely between the direct glacial deposits in europe and those which are more or less modified by water-action. at first sight it would seem also somewhat hazardous to attempt to correlate with any portion of the glacial period the deposition of the gravelly and loamy deposits in valleys, which, like those of the seine and somme, lie entirely outside of the glaciated area. upon close examination, however, the elements of doubt more and more disappear. the glacial period was one of great precipitation, and it is natural to suppose that the area of excessive snow-fall extended considerably beyond the limit of the ice-front. during that period therefore, the rivers of central france must have been annually flooded to an extent far beyond anything which is known at the present time. since these rivers flowed to the northward, at a period when, during the long and severe winters, the annual accumulation of ice near their mouths was excessive, ice-gorges of immense extent, such as now form about the mouths of the siberian rivers, would regularly occur. we are not surprised, therefore, to find, even in these streams, abundant indications of the indirect influence of the great northern ice-sheet. the indications referred to consist of high-level gravel terraces occasionally containing boulders, of from four to five tons weight, which have been transported for a considerable distance. the elevation of the terraces above the present flood-plains of the seine and somme reaches from to feet. we are not to suppose, however, that even in glacial times the floods of the river seine could have filled its present valley to that height. the highest flood in this river known in historic times rose only to a height of twenty-nine feet. mr. prestwich estimates that, without taking into consideration the more rapid discharge, a flood of sixty times this magnitude would be required to fill the present valley to the level of the ancient gravels, while at amiens the shape of the valley of the somme is such that five hundred times the mean average of the stream would be required to reach the high-level gravels. the conclusion, therefore, is that the troughs of these streams have been largely formed by erosion since the deposition of the high-level gravels. connected with these terrace gravels in northern france is a loamy deposit, corresponding to the loess in other parts of europe, and to a similar deposit to which we have referred in describing the southwestern part of the glaciated area in north america. in northern france this fine silt overlies the high-level gravel deposits, and, as mr. prestwich has pretty clearly shown, was deposited contemporaneously with them during the early inundations and before the stream had eroded its channel to its present level. the distribution of loess in europe was doubtless connected with the peculiar glacial conditions of the continent. its typical development is in the valley of the rhine, where it is described by professor james geikie "as a yellow or pale greyish-brown, fine-grained, and more or less homogeneous, consistent, non-plastic loam, consisting of an intimate admixture of clay and carbonate of lime. it is frequently minutely perforated by long, vertical, root-like tubes which are lined with carbonate of lime--a structure which imparts to the loess a strong tendency to cleave or divide in vertical planes. thus it usually presents upright bluffs or cliffs upon the margins of streams and rivers which intersect it. very often it contains concretions or nodules of irregular form.... land-shells and the remains of land animals are the most common fossils of the loess, but occasionally fresh-water shells and the bones of fresh-water fish occur." "from the margins of the modern alluvial flats which form the bottoms of the valleys it rises to a height of or feet above the streams--sweeping up the slopes of the valleys, and imparting a rich productiveness to many districts which would otherwise be comparatively unfruitful. from the rhienthal itself it extends into all the tributary valleys--those of the neckar, the main, the lahn, the moselle, and the meuse, being more or less abundantly charged with it. it spreads, in short, like a great winding-sheet over the country--lying thickly in the valleys and dying off upon the higher slopes and plateaux. wide and deep accumulations appear likewise in the rhône valley, as also in several other river-valleys of france, as in those of the seine, the saône, and the garonne, and the same is the case with many of the valleys of middle germany, such as those of the fulda, the werra, the weser, and the upper reaches of the great basin of the elbe. it must not be supposed that the loess is restricted to valleys and depressions in the surface of the ground. "it is true that it attains in these its greatest thickness, but extensive accumulations may often be followed far into the intermediate hilly districts and over the neighbouring plateaux. thus the odenwald, the taunus, the vogelgebirge, and other upland tracts, are cloaked with loess up to a considerable height. crossing into the drainage system of the danube, we find that this large river and many of its tributaries flow through vast tracts of loess. lower bavaria is thickly coated with it, and it attains a great development in bohemia, upper and lower austria, and moravia--in the latter country rising to an elevation of , feet. it is equally abundant in hungary, galicia, bukowina, and transylvania. from the danubian flat lands and the low grounds of galicia it stretches into the valleys of the carpathians, up to heights of and , feet. in some cases it goes even higher--namely, to , feet, according to zeuschner, and to , or , feet, according to korzistka. these last great elevations, it will be understood, are in the upper valleys of the northern carpathians. in roumania loess is likewise plentiful, but it has not been observed south of the balkans. east of the carpathians--that is to say, in the regions watered by the dniester, the dnieper, and the don--loess appears also to be wanting, and to be represented by those great steppe-deposits which are known as _tchernozen_, or black earth."[bw] [footnote bw: prehistoric europe, pp. - .] the shells found in the loess indicate both a colder and a wetter climate during its deposition than that which now exists. the relics of land animals are infrequently found in the deposit, yet they do occur, but mostly in fragmentary condition--the principal animals represented being the mammoth, the rhinoceros, the reindeer, and the horse; which is about the same variety as is found in the gravel deposits of the glacial period, both in western europe and in america. a species of loess--differing, however, somewhat in color from that on the rhine--covers the plains of northeastern france up to an elevation of feet above the the sea, where, as we have already said, it overlies the high-level gravels of the seine and the somme. above this height the superficial soil in france is evidently merely the decomposed upper surface of the native rock. the probable explanation of all these deposits, included under the term "loess," is the same as that already given by prestwich of the loamy deposits of northern france. but in case of rivers, which, like the rhine, encountered the ice-front in their northward flow, a flooded condition favouring the accumulation of loess was doubtless promoted by the continental ice-barrier. in the case of the danube and the rhône, however, where there was a free outlet away from the glaciated region, the loess in the upper part of the valleys must have accumulated in connection with glacial floods quite similar to those which we have described as spreading over the imperfectly formed water-courses of the mississippi basin during the close of the ice age. that the typical loess is of glacial origin is pretty certainly shown, both by its distribution in front of glaciers and by its evident mechanical origin when studied under the microscope. it is, in short, the fine sediment which gives the milky whiteness to glacial rivers. in central russia there is a considerable area in which the glacial conditions were, in one respect, similar to those in the northern part of the mississippi valley in the united states. in both regions the continental ice-sheet surmounted the river partings, and spread over the upper portion of an extensive plain whose drainage was to the south. the dnieper, the don, and the western branch of the volga, like the ohio and the mississippi, have their head-waters in the glaciated region. in some other respects, also, there is a resemblance between the plains bordering the glaciated region in central russia and those which in america border it in the mississippi valley. mr. james geikie is of the opinion that the extensive belt of black earth adjoining the glaciated area in russia, and constituting the most productive agricultural portion of the country, derives its fertility, as does much of the mississippi valley, from the blanket of glacial silt spread pretty evenly over it. thus it would appear that in europe, as in america, the ice of the glacial period was a most beneficent agent, preparing the face of the earth for the permanent occupation of man. on both continents the seat of empire is in the area once occupied by the advance of the great ice-movements of that desolate epoch. _asia._ east of the urals, in northern asia, there is no evidence of moving ice upon the land during the glacial period; but at yakutsk, in latitude ° north, the soil is frozen at the present time to an unknown depth, and many of the siberian rivers, as they approach and empty into the arctic sea, flow between cliffs of perpetual ice or frozen ground. the changes that came over this region during the glacial period are impressively indicated by the animal remains which have been preserved in these motionless icy cliffs. in the early part of the period herds of mammoth and woolly rhinoceros roamed over the plains of siberia, and waged an unequal warfare with the slowly converging and destructive forces. the heads and tusks of these animals were so abundant in siberia that they long supplied all russia with ivory, besides contributing no small amount for export to other countries. "in and as many as , mammoth-tusks, weighing from to pounds each, were entered at the london clocks."[bx] so perfectly have the carcasses of these extinct animals been preserved in the frozen soil of northern siberia that when, after the lapse of thousands of years, floods have washed them out from the frozen cliffs, dogs and wolves and bears have fed upon their flesh with avidity. in some instances even "portions of the food of these animals were found in the cavities of the teeth. microscopic examination showed that they fed upon the leaves and shoots of the coniferous trees which then clothed the plains of siberia." a skeleton and parts of the skin, and some of the softer portions of the body of a mammoth, discovered in in the frozen cliff near the mouth of the lena, was carried to st. petersburg in , from which it was ascertained that this huge animal was "covered with alight-coloured, curly, very thick-set hair one to two inches in length, interspersed with darker-colored hair and bristles from four to eighteen inches long."[by] [footnote bx: prestwich's geology, vol. ii, p. .] [footnote by: prestwich's geology, vol. ii, p. .] in the valleys of sikkim and eastern nepaul, in northern india, glaciers formerly extended , feet lower than now, or to about the , -foot level, and in the western himalayas to a still lower level. the higher ranges of mountains in other portions of asia also show many signs of former glaciation. this is specially true of the caucasus, where the ancient glaciers were of vast extent. according, also, to sir joseph hooker, the cedars of lebanon flourish upon an ancient moraine. of the glacial phenomena in other portions of asia little is known. _africa._ northern and even central africa must likewise come in for their share of attention. the atlas mountains, rising to a height of , feet, though supporting none at the present time, formerly sustained glaciers of considerable size. moraines are found in several places as low as the , -foot level, and one at an altitude of , feet is from to feet high, and completely crosses and dams up the ravine down which the glacier formerly came. some have supposed that there are indubitable evidences of former glaciation in the mountain-ranges of southwestern africa between latitude ° and °, but the evidence is not as unequivocal as we could wish, and we will not pause upon it. the mountains of _australia_, also, some of which rise to a height of more than , feet, are supposed to have been once covered with glacial ice down to the level of , feet, but the evidence is at present too scanty to build upon. but in _new zealand_ the glaciers now clustering about the peaks in the middle of the south island, culminating in mount cook, are but diminutive representatives of their predecessors. this is indicated by extensive moraines in the lower part of the valleys and by the existence of numerous lakes, attributable, like so many in europe and north america, to the irregular deposition of morainic material by the ancient ice-sheet.[bz] [footnote bz: see with axe and rope in the new zealand alps, by g. e. mannering, .] chapter vii. drainage systems and the glacial period. we will begin the consideration of this part of our subject, also, with the presentation of the salient facts in north america, since that field is simpler than any field in the old world. the natural drainage basins of north america east of the rocky mountains are readily described. the mississippi river and its branches drain nearly all the region lying between the appalachian chain and the rocky mountains and south of the dominion of canada and of the great lakes. all the southern tributaries to the great lakes are insignificant, the river partings on the south being reached in a very short distance. the drainage of the rather limited basin of the great lakes is northeastward through the st. lawrence river, leaving nearly all of the dominion of canada east of the rocky mountains to pour its surplus waters northward into hudson bay and the arctic ocean. with the exception of the st. lawrence river, these are essentially permanent systems of drainage. to understand the extent to which the ice of the glacial period modified these systems, we must first get before our minds a picture of the country before the accumulation of ice began. _preglacial erosion._ reference has already been made to the elevated condition of the northern and central parts of north america at the beginning of the glacial period. the direct proof of this preglacial elevation is largely derived from the fiords and great lake basins of the continent. the word "fiord" is descriptive of the deep and narrow inlets of the sea specially characteristic of the coasts of norway, denmark. iceland, and british columbia. usually also fiords are connected with valleys extending still farther inland, and occupied by streams. fiords are probably due in great part to river erosion when the shores stood at considerably higher level than now. slowly, during the course of ages, the streams wore out for themselves immense gorges, and were assisted, perhaps, to some extent by the glaciers which naturally came into existence during the higher continental elevation. the present condition of fiords, occupied as they usually are by great depths of sea-water, would be accounted for by recent subsidence of the land. in short, fiords seem essentially to be submerged river gorges, partially silted up near their mouths, or perhaps partially closed by terminal moraines. it is not alone in northwestern europe and british columbia that fiords are found, but they characterize as well the eastern coast of america north of maine, while even farther south, both on the atlantic and on the pacific coast, some extensive examples exist, whose course has been revealed only to the sounding-line of the government survey. the most remarkable of the submerged fiords in the middle atlantic region of the united states is the continuation of the trough of hudson river beyond new york bay. as long ago as the work of the united states coast survey showed that there was a submarine continuation of this valley, extending through the comparatively shallow waters eighty miles or more seaward from sandy hook. [illustration: fig. .--map showing old channel and mouth of the hudson (dewberry).] the more accurate surveys conducted from to have brought to our knowledge the facts about this submarine valley almost as clearly as those relating to the inland portion of it above new york city. according to mr. a. lindenkohl,[ca] this submarine valley began to be noticeable in the soundings ten miles southeast of sandy hook. the depth of the water where the channel begins is nineteen fathoms ( feet). ten miles out the channel has sunk ninety feet below the general depth of the water on the bank, and continues at this depth for twenty miles farther. this narrow channel continues with more or less variation for a distance of seventy-five miles, where it suddenly enlarges to a width of three miles and to a depth of fathoms, or , feet, and extends for a distance of twenty-five miles, reaching near that point a depth of fathoms, or , feet. according to mr. lindenkohl, this ravine maintains for half its length "a vertical depth of more than , feet, measuring from the top of its banks, and the banks have a nearly uniform slope of about °." the mouth of the ravine opens out into the deep basin of the central atlantic. [footnote ca: bulletin of the geological society of america, vol. i, p. ; american journal of science, june, .] with little question there is brought to light in these remarkable investigations a channel eroded by the extension of the hudson river, into the bordering shelf of the atlantic basin at a time when the elevation of the continent was much greater than now. this is shown to have occurred in late tertiary or post-tertiary times by the fact that the strata through which it is worn are the continuation of the tertiary deposits of new jersey. the subsidence to its present level has probably been gradual, and, according to professor cook, is still continuing at the rate of two feet a century. similar submarine channels are found extending out from the present shore-line to the margin of the narrow shelf bordering the deep water of the central atlantic running from the mouth of the st. lawrence river, through st. lawrence bay, and through delaware and chesapeake bays.[cb] all these submerged fiords on the atlantic coast were probably formed during a continental elevation which commenced late in the tertiary period, and reached the amount of from , to , feet in the northern part of the continent. [footnote cb: see lindenkohl in american journal of science, for june, .] [illustration: fig. .--new york harbor in preglacial times looking south, from south end of new york island (newberry).] to this period must probably be referred also the formation of the gorge, or more properly fiord, of the saguenay, which joins the st. lawrence below quebec. the great depth of this fiord is certainly surprising, since, according to sir william dawson, its bottom, for fifty miles above the st. lawrence, is feet below the sea-level, while the bordering cliffs are in some places , feet above the water. the average width is something over a mile. it seems impossible to account for such a deep gorge extending so far below the sea-level, except upon the supposition of a long-continued continental elevation, which should allow the stream to form a cañon to an extent somewhat comparable with that of the cañons of the colorado and other rivers in the far west. then, upon the subsidence of the continent to the present level, it would remain partially or wholly submerged, as we find it at the present time. during the glacial period it was so filled with ice as to prevent silting up. the rivers entering the pacific ocean, both in the united states and in british columbia, are also lost in submerged channels extending out to the deeper waters of the pacific basin in a manner closely similar to the atlantic streams which have been mentioned. during this continental elevation which preceded, accompanied, and perhaps brought on the glacial period, erosion must have proceeded with great intensity along all the lines of drainage, and throughout the whole region which is now covered, and to a considerable extent smoothed over, by glacial deposits, and the whole country must have presented a very different appearance from what it does now. a pretty definite idea of its preglacial condition can probably be formed by studying the appearance of the regions outside of and adjoining that which was covered by the continental glacier. the contrast between the glaciated and the unglaciated region is striking in several respects aside from the presence and absence of transported rocks and other _débris_, but in nothing is it greater than in the extent of river erosion which is apparent upon the surface. for example, upon the western flanks of the alleghanies the regions south of the glacial limit is everywhere deeply channeled by streams. indeed, so long have they evidently been permitted to work in their present channels that, wherever there have been waterfalls, they have receded to the very head-waters, and no cataracts exist in them at the present time. nor are there in the unglaciated region any lakes of importance, such as characterize the glaciated region. if there have been lakes, the lapse of time has been sufficient for their outlets to lower their beds sufficiently to drain the basins dry. on entering the glaciated area all this is changed. the ice-movement has everywhere done much to wear down the hills and fill the valleys, and, where there was _débris_ enough at command, it has obliterated the narrow gorges originally occupied by the preglacial streams. thus it has completely changed the minor lines of superficial drainage, and in many instances has produced most extensive and radical changes in the whole drainage system of the region. in the glaciated area, channels buried beneath glaciated _débris_ are of frequent occurrence, while many of the streams which occupy their preglacial channels are flowing at a very much higher level than formerly, the lower part of the channel having been silted up by the superabundant _débris_ accessible since the glacial movement began. _buried outlets and channels._ it is easy to see how the great number of shallow lakes which frequent the glaciated region were formed by the irregular deposition of glacial _débris_, but it is somewhat more difficult to trace out the connection between the glacial period and the great lakes of north america, several of which are of such depth that their bottoms are some hundreds of feet below the sea-level, lake erie furnishing the only exception. this lake is so shallow that it is easy to see how its basin may have been principally formed by river erosion, while it is evident that such must have been the mode of its formation, since it is surrounded by sedimentary strata lying nearly in a horizontal position. [illustration: fig. .--section across the valley of the cuyahoga river, twenty miles above its mouth (claypole).] that lake erie is really nothing but a "glacial mill-pond" is proved also by much direct evidence, especially that derived from the depth of the buried channels of the streams flowing into it from the south. of these, the cuyahoga river, which enters the lake at cleveland, has been most fully investigated. in searching for oil, some years ago, borings were made at many places for twenty-five miles above the mouth of the river. as a result, it appeared that for the whole distance the rocky bottom of the gorge was about two hundred feet below the present bottom of the river, while the river itself is two or three hundred feet below the general level of the country, occupying a trough about half a mile in width, with steep, rocky sides. these facts indicate that at one time the river must have found opportunity to discharge its contents at a level two hundred feet below that of the present lake, while an examination of the material filling up the bottom of the gorge to its present level shows it to be glacial _débris_, thus proving that the silting up was accomplished during the glacial period. as the water of lake erie is for the most part less than one hundred feet in depth, and is nowhere much more than two hundred feet deep, it is clear that the preglacial outlet which drained it down to the level of the rocky bottom of the cuyahoga river must have destroyed the lake altogether. hence ave may be certain that, before the glacial period, the area now covered by the lake was simply a broad, shallow valley through which there coursed a single river of great magnitude, with tributary branches occupying deep gorges. professor j. w. spencer has shown with great probability that the old line of drainage from lake erie passed through the lower part of the valley of grand river, in canada, and entered lake ontario at its western extremity, and that during the great ice age this became so completely obstructed with glacial _débris_ as to form an impenetrable dam, and to cause the pent-up water to flow through the niagara valley, which chanced to furnish the lowest opening. in speaking of the present area of lake erie, however, as being then occupied by a river valley, we do not mean to imply that it was not afterwards greatly modified by glacial erosion; for undoubtedly this was the case, whatever views we may have as to the relative efficiency of ice and water in scooping out lake basins. in the case of lake erie, we need suppose no change of level to account for the erosion of its basin, but only that, since the strata in which it is situated were deposited, time enough had elapsed for a great river to cut a gorge extending from the western end of lake ontario through to the present bed of lake erie, and that here a great enlargement of the valley was occasioned by the existence of deep beds of soft shale which could easily be worn away by a ramifying system of tributary streams. rivers acting at present relative levels would be amply sufficient to produce the results which are here manifest. but in the case of lakes ontario, huron, michigan, and superior, whose depths descend considerably below the sea-level, we must suppose that they were, in the main, eroded when the continent was so much elevated that their bottoms were brought above tide-level. the depth of lake ontario implies the existence of an outlet more than four hundred feet lower than at present, which, of course, could exist only when the general elevation was more than four hundred feet greater than now. the existence of an outlet at that depth seems to be proved also by the fact that at syracuse, where numerous wells have been sunk to obtain brine for the manufacture of salt, deposits of sand, gravel, and rolled stones, four hundred and fifty feet thick, are penetrated without reaching rock. since this lies in the basin of lake ontario, it follows that if the basin itself has been produced by river erosion, the land must have been of sufficient height to permit an outlet through a valley, or cañon, of the required depth, and this outlet must now be buried beneath the abundant glacial _débris_ that covers the region. professor newberry, who has studied the vicinity carefully, is of the opinion that there is ample opportunity for such a line of drainage to have extended through the mohawk valley to the hudson river. but, at little falls, a spur of the adirondack mountains projects into the valley, and the archæan rocks over which the river runs are so prominent and continuous that some have thought it impossible for the requisite channel to have ever existed there. extensive deposits of glacial _débris_, however, are found in the vicinity, especially in places some distance to the north, and in professor newberry's opinion the existence of a buried channel around the obstruction upon the north side is by no means improbable. the preglacial drainage of lake huron has not been determined with any great degree of probability. professor spencer formerly supposed that it passed from the southern end of the lake through london, in the western part of ontario, and reached the erie basin near port stanley, and so augmented the volume of the ancient river which eroded the buried cañon from lake erie to lake ontario. but he now supposes, though the evidence is by no means demonstrative, that the waters of lake huron passed into lake ontario by means of a channel extending from georgian bay to the vicinity of toronto. with a fair degree of probability, the basin of lake superior is supposed by professor newberry to have been joined to that of lake michigan by some passage, now buried, considerably to the west of the strait of mackinac, and thence to have had an outlet southward from the vicinity of chicago directly into the mississippi river. of this there is considerable evidence furnished by deeply buried channels which have been penetrated by borings in various places in kankakee, livingston, and mclean counties, illinois; but the whole area extending from lake michigan to the mississippi is so deeply covered with glacial _débris_ that the surface of the country gives no satisfactory indication of the exact lines of preglacial drainage. some of the most remarkable instances of ancient river channels buried by the glacial deposits have been brought to light in southwestern ohio, where there has been great activity in boring for gas and oil. at st. paris, champaign county, for example, in a locality where the surface of the rock near by was known to be not far below the general level, a boring was begun and continued to a depth of more than five hundred feet without reaching rock, or passing out of glacial _débris_. many years ago professor newberry collected sufficient facts to show that pretty generally the ancient bed of the ohio river was as much as feet below that over which it now flows. during a continental elevation the erosion had proceeded to that extent, and then the channel had been silted up during the glacial period with the abundant material carried down by the streams from the glaciated area. one of the evidences of the preglacial depth of the channel of the ohio was brought to light at cincinnati, where "gravel and sand have been found to extend to a depth of over one hundred feet below low-water mark, and the bottom of the trough has not been reached." in the valley of mill creek, also, "in the suburbs of cincinnati, gravel and sand were penetrated to the depth of feet below the stream before reaching rock." but from the general appearance of the channel, professor j. f. james was led to surmise that a rock bottom extended all the way across the present channel of the ohio, between price hill and ludlow, ky., a short distance below cincinnati, which would preclude the possibility of a preglacial outlet at the depth disclosed in that direction. mr. charles j. bates (who was inspector of the masonry for the cincinnati southern railroad while building the bridge across the ohio at this point) informs me that mr. james's surmise is certainly correct, and that his "in all probability" may be displaced by "certainly," since the bedded rocks supposed by professor james to extend across the river a few feet below its present bottom were found by the engineers to be in actual existence. in looking for an outlet for the waters of the upper ohio which should permit them to flow off at the low level reached in the channel at cincinnati, professor james was led to inspect the valley extending up mill creek to the north towards hamilton, where it joins the great miami. the importance of mill creek valley is readily seen in the fact that the canal and the railroads have been able to avoid heavy grades by following it from cincinnati to hamilton. as a glance at a map will show, it is also practically but a continuation of the northerly course pursued by the ohio for twenty miles before reaching cincinnati. this, therefore, was a natural place in which to look beneath the extensive glacial _débris_ for the buried channel of the ancient ohio, and here in all probability it has been found. the borings which have been made in milk creek valley north of cincinnati, show that the bedded rock lies certainly thirty-four feet below the low-water mark of the ohio just below cincinnati, while at hamilton, twenty-five miles north of cincinnati, where the valley of the great miami is reached, the bedded rock of the valley lies as much as ninety feet below present low-water mark in the ohio. other indications of the greater depth of the preglacial gorge of the ohio are abundant. "at the junction of the anderson with the ohio, in indiana, a well was sunk ninety-four feet below the level of the ohio before rock was found." at louisville, ky., the occurrence of falls in the ohio seemed at first to discredit the theory in question, but professor newberry was able to show that the falls at louisville are produced by the water's being now compelled to flow over a rocky point projecting from the north side into the old valley, while to the south there is ample opportunity for an old channel to have passed around this point underneath the city on the south side. the lowlands upon which the city stands are made lands, where glacial _débris_ has filled up the old channel of the ohio. above cincinnati the tributaries of the ohio exhibit the same phenomena. at new philadelphia, tuscarawas county, the borings for salt-wells show that the tuscarawas is running feet above its ancient bed. the beaver, at the junction of the mahoning and shenango, is flowing feet above the bottom of its old trough, as is demonstrated by a large number of oil-wells bored in the vicinity. oil creek is shown by the same proofs to run from to feet above its old channel, and that channel had sometimes vertical and even overhanging walls.[cc] [footnote cc: geological survey of ohio, vol. ii, pp. , .] the course of preglacial drainage in the upper basin of the alleghany river is worthy of more particular mention. mr. carll, of the pennsylvania geological survey, has adduced plausible reasons for believing that previous to the glacial period the drainage of the valley of the upper alleghany north of the neighbourhood of tidioute, in warren county, instead of passing southward as now, was collected into one great stream flowing northward through the region of cassadaga lake to enter the lake erie basin at dunkirk, n. y. the evidence is that between tidioute and warren the present alleghany is shallow, and flows over a rocky basin; but from warren northward along the valley of the conewango, the bottom of the old trough lies at a considerably lower level, and slopes to the north. borings show that in thirteen miles the slope of the preglacial floor of conewango creek to the north is feet. the actual height above tide of the old valley floor at fentonville, where the conewango crosses the new york line, is only feet; while that of the ancient rocky floor of the alleghany at great bend, a few miles south of warren, was , feet. again, going nearer the head-waters of the alleghany, in the neighbourhood of salamanca, it is found that the ancient floor of the alleghany is, at carrollton, feet lower than the ancient bed of the present stream at great bend, about sixty miles to the south; while at cole's spring, in the neighbourhood of steamburg, cattaraugus county, n. y., there has been an accumulation of feet of drift in a preglacial valley whose rocky floor is feet below the ancient rocky floor at great bend. unless there has been a great change in levels, there must, therefore, have been some other outlet than the present for the waters collecting in the drainage basin to the north of great bend.[cd] [footnote cd: for a criticism of mr. carll's views, see an article on pleistocene fluvial planes of western pennsylvania, by mr. frank leverett, in american journal of science, vol. xlii, pp. - .] while there are numerous superficial indications of buried channels running towards lake erie in this region, direct exploration has not been made to confirm these theoretical conclusions. in the opinion of mr. carll, chautauqua lake did not flow directly to the north, but, passing through a channel nearly coincident with that now occupied by it, joined the northerly flowing stream a few miles northeast from jamestown.[ce] it is probable, however, that chautauqua did not then exist as a lake, since the length of preglacial time would have permitted its outlet to wear a continuous channel of great depth corresponding to that known to have existed in the conewango and upper alleghany. [footnote ce: second geological survey of pennsylvania, vol. iii.] the foregoing are but a few of the innumerable instances where the local lines of drainage have been disturbed, and even permanently changed, by the glacial deposits. almost every lake in the glaciated region is a witness to this disturbance of the established lines of drainage by glacial action, while in numerous places where lakes do not now exist they have been so recently drained that their shore-lines are readily discernible. an interesting instance of the recent disappearance of one of these glacial lakes is that of runaway pond, in northern vermont. in the early part of the century the lamoille river had its source in a small lake in craftsbury, orleans county. the sources of the missisquoi river were upon the same level just to the north, and the owner of a mill privilege upon this latter stream, desiring to increase his power by obtaining access to the water of the lake, began digging a ditch to turn it into the missisquoi, but no sooner had he loosened the thin rim of compact material which formed the bottom and the sides of the inclosure, than the water began to rush out through the underlying and adjacent quicksands. this almost instantly enlarged the channel, and drained the whole body of water oft in an incredibly short time. as a consequence, the torrent went rushing down through the narrow valley, sweeping everything before it; and nothing but the unsettled condition of the country prevented a disaster like that which occurred in at johnstown, pa. doubtless there are many other lakes held in position by equally slender natural embankments. artificial reservoirs are by no means the only sources of such danger. the buried channel of the old mississippi river in the vicinity of minneapolis is another instructive example of the instability of many of the present lines of drainage. the gorge of the mississippi river extending from fort snelling to the falls of st. anthony at minneapolis is of post-glacial origin. one evidence of this is its narrowness when contrasted with the breadth of the valley below fort snelling. below this point the main trough of the mississippi has a width of from two to eight miles, and the faces of the bluffs on either side show the marks of extreme age. the tributary streams also have had time to wear gorges proportionate to that of the main stream, and the agencies which oxidise and discolor the rocks have had time to produce their full effects. but from fort snelling up to minneapolis, a distance of about seven miles, the gorge is scarcely a quarter of a mile in width, and the faces of the high, steep bluffs on either side are remarkably fresh looking by comparison with those below; while the tributary gorges, of which that of the minnehaha river is a fair specimen, are very limited in their extent. upon looking for the cause of this condition of things we observe that the broad trough of the mississippi river, which had characterised it all the way below fort snelling, continues westward, without interruption, up the valley of the present minnesota river, and, what seems at first most singular, it does not cease at the sources of the minnesota, but, through lake traverse and big stone lake, is continuous with the trough of the red river of the north. [illustration: fig. .--map of mississippi river from fort snelling to minneapolis and the vicinity, showing the extent of the recession of the falls of st. anthony since the great ice age. notice the greater breadth of the valley of the minnesota river as described in the text (winchell).] deferring, however, for a little the explanation of this, we will go back to finish the history of the preglacial channel around the falls of st. anthony. as early as the year professor n. h. winchell had collected sufficient evidence from wells, one of which had been sunk to a depth of one hundred and seventy-five feet, to show that the preglacial course of the stream corresponding to the present mississippi river ran to the west of minneapolis and of the falls of minnehaha, and joined the main valley some distance above fort snelling, as shown in the accompanying map. this condition of things was at one time very painfully brought to the notice of the citizens of minneapolis. a large part of the wealth of the city at that time consisted of the commercial value of the water-power furnished by the falls of st. anthony. to facilitate the discharge of the waste water from their wheels, some mill-owners dug a tunnel through the soft sandstone underlying the limestone strata over which the river falls; but it very soon became apparent that the erosion was proceeding with such rapidity that in a few years the recession of the falls would be carried back to the preglacial channel, when the river would soon scour out the channel and destroy their present source of wealth. the citizens rallied to protect their property, and spent altogether as much as half a million dollars in filling up the holes that had been thoughtlessly made; but so serious was the task that they were finally compelled to appeal for aid to the united states government. permanent protection was provided by running a tunnel, some ways back from the falls, completely across the channel, through the soft sandstone underlying the limestone, and filling this up with cement hard enough and compact enough to prevent the further percolation of the water from above. _ice-dams._ the foregoing changes in lines of drainage due to the glacial period were produced by deposits of earthy material in preglacial channels. another class of temporary but equally interesting changes were produced by the ice itself acting directly as a barrier. many such lakes on a small scale are still in existence in various parts of the world. the merjelen see in switzerland is a well-known instance. this is a small body of water held back by the great aletsch glacier, in a little valley leading to that of the fiesch glacier, behind the eggischorn. at irregular intervals the ice-barrier gives way, and allows the water to rush out in a torrent and flood the valley below. afterwards the ice closes up again, and the water reaccumulates in preparation for another flood. other instances in the alps are found in the mattmark see, which fills the portion of the saas valley between monte rosa and the rhône. this body of water is held in place by the allalin glacier, which here crosses the main valley. the lac du combal is held back by the glacier de miage at the southern base of mont blanc. "a more famous case is that of the gietroz glacier in the valley of bagnes, south of martigny. in this lake had grown to be a mile long, and was feet wide and feet deep. an attempt was made to drain it by cutting through the ice, and about half the water was slowly drawn off in this way; but then the barrier broke, and the rest of the lake was emptied in half an hour, causing a dreadful flood in the valley below. in the tyrol, the vernagt glacier has many times caused disastrous floods by its inability to hold up the lake formed behind it. in the northwestern himalaya, the upper branches of the indus are sometimes held back in this way. a noted flood occurred in ; it advanced twenty-five miles in an hour, and was felt three hundred miles down-stream, destroying all the villages on the lower plain, and strewing the fields with stones, sand, and mud."[cf] [footnote cf: professor william m. davis in. proceedings of the boston society of natural history, vol. xxi, pp. , .] in greenland such temporary obstructions are frequent, forming lakes of considerable size. instances occur, in connection with the jakobshavn and the frederickshaab glaciers, and in the north isortok and alangordlia fiords. frequently, also, bodies of water of considerable size are found in depressions of the ice itself, even at high levels. i have myself seen them covering more than an acre, and as much as a thousand feet above the sea-level, upon the surface of the muir glacier, alaska. they are reported by mr. i. c. russell[cg] of larger size and at still higher elevations upon the glaciers radiating from mount st. elias; while the explorers of greenland mention them of impressive size upon the surface of its continental ice-sheet. [footnote cg: see national geographic magazine, vol. iii, pp. - .] with these facts in mind we can the more readily enter into the description which will now be given of some temporary lakes of vast size which were formed by direct ice-obstructions during portions of the period. one of the most interesting of these is illustrated upon the accompanying map, which will need little description. [illustration: fig. .--map showing the effect of the glacial dam at cincinnati (claypole). (from transactions of the edinburgh geological society.)] while tracing the boundary-line of the glaciated area in the mississippi valley during the summer of , i discovered the existence of unmistakable glacial deposits in boone county, kentucky, across the ohio river, from cincinnati.[ch]; these deposits were upon the height of land feet above the ohio river, or nearly , feet above the sea, which is about the height of the water-shed between the licking and kentucky rivers. as the ohio river occupies a trough of erosion some hundreds of feet in depth, and extending all the way from this point to the mountains of western pennsylvania, it would follow that the ice which conveyed boulders across the ohio river at cincinnati, and deposited them upon the highlands between the licking and kentucky rivers, would so obstruct the channel of the ohio as to pond the water back, and hold it up to the level of the lowest pass into the ohio river farther down. direct evidences of obstruction by glacial ice appear also for a distance of fifty or sixty miles, extending both ways, from cincinnati. [footnote ch: the existence of portions of this evidence had previously been pointed out by mr. robert b. warder and dr. george sutton (see geological reports of indiana, and ).] the consequences connected with this state of things are of the most interesting character. the bottom of the ohio river at cincinnati is feet above the sea-level. a dam of feet would raise the water in its rear to a height of feet above tide. this would produce a long, narrow lake, of the width of the eroded trough of the ohio, submerging the site of pittsburg to a depth of feet, and creating slack water up the monongahela nearly to grafton, west virginia, and up the alleghany as far as oil city. all the tributaries of the ohio would likewise be filled to this level. the length of this slack-water lake in the main valley, to its termination up either the alleghany or the monongahela, was not far from one thousand miles. the conditions were also peculiar in this, that all the northern tributaries rose within the southern margin of the ice-front, which lay at varying distances to the north. down these there must have poured during the summer months immense torrents of water to strand boulder-laden icebergs on the summits of such high hills as were lower than the level of the dam. naturally enough, this hypothesis of a glacial dam at cincinnati aroused considerable discussion, and led to some differences of opinion. professors i. c. white and j. p. lesley, whose field work has made them perfectly familiar with the upper ohio and its tributaries, at once supported the theory, with a great number of facts concerning certain high-level terraces along the alleghany and monongahela rivers; while additional facts of the same character have been brought to light by myself and others. in general, it may be said that in numerous places terraces occur at a height so closely corresponding to that of the supposed dam at cincinnati, that they certainly strongly suggest direct dependence upon it. the upward limit of these terraces in the monongahela river is , feet, and they are found in various places in situations which indicate that they were formed in still water of such long standing as would require an obstruction below of considerable permanence. one of the most decisive cases adduced by professor white occurs near morgantown, in west virginia, of which he gives the following description: "owing to the considerable elevation-- feet--of the fifth terrace above the present river-bed in the vicinity of morgantown, its deposits are frequently found far inland from the monongahela, on tributary streams. a very extensive deposit of this kind occurs on a tributary one mile and a half northeast of morgantown; and the region, which includes three or four square miles, is significantly known as the 'flats.' the elevation of the 'flats' is feet above the river, or , feet above tide. the deposits on this area consist almost entirely of clays and fine, sandy material, there being very few boulders intermingled. the depth of the deposit is unknown, since a well sunk on the land of mr. baker passed through alternate beds of clay, fine sand, and muddy trash, to a depth of sixty-five feet without reaching bed-rock. in some portions of the clays which make up this deposit, the leaves of our common forest-trees are found most beautifully preserved. "at clarksburg, where the river unites with elk creek, there is a wide stretch of terrace deposits, and the upper limit is there about , feet above tide, or only feet above low-water ( feet); while at weston, forty miles above (by the river), these deposits cease at seventy feet above low water, which is there feet above tide. it will thus be observed that the upper limit of the deposits retains a practical horizontality from morgantown to weston, a distance of one hundred miles, since the upper limit has the same elevation above tide ( , to , feet) at every locality. "these deposits consist of rounded boulders of sandstone, with a large amount of clay, quicksand, and other detrital matter. the country rock in this region consists of the soft shales and limestones of the upper coal-measures, and hence there are many 'low gaps' from the head of one little stream to that of another, especially along the immediate region of the river; and in every case the summits of these divides, where they do not exceed an elevation of , feet above tide, are covered with transported or terrace material; but where the summits go more than a few feet above that level we find no transported material upon them, but simply the decomposed country rock." other noteworthy terraces naturally attributable to the cincinnati ice-dam are to be found in the valley of the kanawha, in west virginia, and one of special significance on the pass between the valleys of the ohio and monongahela, west of clarksburg, west virginia. according to professor white, there is at this latter place "a broad, level summit, having an elevation of , feet, in a gap about feet below the enclosing hills. this gap, or valley, is covered by a deposit of fine clay. the cut through it is about thirty feet, and one can observe the succession of clays of all kinds and of different colours, from yellow on the surface down to the finest white potter's clay at the level of the railway, where the cut reaches bed-rock, thus proving that the region has been submerged."[ci] [footnote ci: bulletin of the geological society of america, vol. i, p. .] another crucial case i have myself described at bellevue, in the angle of the ohio and alleghany rivers, about five miles below pittsburg, where the gravel terrace is nearly feet above the river, making it about , feet above the sea. a significant circumstance connected with this terrace is that not only does its height correspond with that of the supposed obstruction at cincinnati, but it contains many pebbles of canadian origin, which could not have got into the valley of the alleghany before the glacial period, and could only have reached their present position by being brought down the alleghany river upon floating ice, or by the ordinary movement of gravel along the margin of a river. thus this terrace, while corresponding closely with the elevation of those on the monongahela river, is directly connected with the glacial period, and furnishes a twofold argument for our theory. a still stronger case occurs at beech flats, at the head of ohio brush creek, in the northwest corner of pike county, ohio, where, at an elevation of about feet above the sea, there is an extensive flat-topped terrace just in front of the terminal moraine. this terrace consists of fine loam, such as is derived from the glacial streams, but which must have been deposited in still water. the occurrence of still water at that elevation just in front of the continental ice-sheet is best accounted for by the supposed dam at cincinnati. indeed, it is extremely difficult to account for it in any other way. there are, however, two other methods of attempting to account for the class of facts above cited in support of the ice-dam theory, of which the most plausible is, that in connection with the glacial period there was a subsidence of the whole region to an extent of , feet. the principal objection heretofore alleged against this supposition is that there are not corresponding signs of still-water action at the same level on the other side of the alleghany mountains. this will certainly be fatal to the subsidence theory, if it proves true. but it is possible that sufficient search for such marks has not yet been made on the eastern side of the mountains. the other theory to account for the facts is, that the terraces adduced in proof of the cincinnati ice-dam were left by the streams in the slow process of lowering their beds from their former high levels. this is the view advocated by president t. c. chamberlin. but the freshness of the leaves and fragments of wood, such as were noted by professor white at morgantown, and the great extent of fine silt occasionally resting upon the summits of the water-sheds, as described above, near clarksburg, bear strongly against it. furthermore, to account for the terrace described at bellevue, which contains canadian pebbles, president chamberlin is compelled to connect the deposit with his hypothetical first glacial epoch, and to assume that all the erosion of the alleghany and monongahela rivers, and indeed of the whole trough of the ohio river, took place in the interval between the "first" and the "second" glacial periods (for he would connect the glacial deposits upon the south side of the river at cincinnati with the first glacial epoch)--all of which, it would seem, is an unnecessary demand upon the forces of nature, when the facts are so easily accounted for by the simple supposition of the dam at cincinnati.[cj] [footnote cj: see matter discussed more at length in the lee age, pp. - , - ; bulletin of the united states geological survey, no. , pp. - ; popular science monthly, vol. xlv, pp. - . _per contra_, mr. frank leverett, in american geologist, vol. x, pp. - .] [illustration: fig. .--map showing the condition of things when the ice-front had withdrawn about on hundred and twenty miles, and while it still filled the valley of the mohawk. the outlet was then through the wabash. niagara was not yet born (claypole). (transactions of the edinburgh geological society.)] we have already described[ck] the various temporary lakes and lines of drainage caused by the direct obstruction of the northward outlets to the basin of the great lakes. in connection with the map, it will be unnecessary to do anything more here than add a list of such temporary southern outlets from the erie-ontario basin.[cl] the first is at fort wayne, indiana, through a valley connecting the maumee river basin with that of the wabash. the channel here is well defined, and the high-level gravel terraces down the wabash river are a marked characteristic of the valley. the elevation of this col above the sea is feet. similar temporary lines of drainage existed from the st. mary's river to the great miami, at an elevation of feet; from the sandusky river to the scioto, through the tymochtee gap, at an elevation of feet; from black river to the killbuck (a tributary of the muskingum) through the harrisville gap, at feet; from the cuyahoga into the tuscarawas valley, through the akron gap, at feet; from grand river into the mahoning, through the orwell gap, feet; from cattaraugus creek, n. y., into the alleghany valley through the dayton gap, about , feet; between conneaut creek and shenango river, at summit station, , feet; from the genesee river, n. y., into the head-waters of the canisteo, a branch of the susquehanna, at portageville, , feet; from seneca lake to chemung river, at horseheads, feet; from cayuga lake to the valley of cayuga creek, at spencer, n. y., , feet; from utica, n. y., into the chenango valley at hamilton, about feet. [footnote ck: see pp. seq., _seq._] [footnote cl: see also accompanying map.] [illustration: fig. .--map illustrating a stage in the recession of the ice in ohio. for a section of the deposit in the bed of this lakelet, see page . the gravel deposits formed at this stage along the outlet into the tuscarawas river are very clearly marked (claypole). (transactions of the edinburgh geological society.)] perhaps it would have been best to give this list in the reverse order, which would be more nearly chronological, since it is clear that the highest outlets are the oldest. we should then have to mention, after the fort wayne outlet, two others at lower levels which are pretty certainly marked by distinct beach ridges upon the south side of lake erie. the first was opened when the ice had melted back from the south peninsula of michigan to the water-shed across from the shiawassee and grand rivers, uncovering a pass which is now feet above the sea. this continued to be the outlet of lake erie-ontario until the ice had further retreated beyond the strait of mackinac, when the water would fall to the level of the old outlet from lake michigan into the illinois river, which is a little less than feet, where it would remain until the final opening of the mohawk river in new york attracted the water in that direction, and lowered the level to that of the pass from lake ontario to the mohawk at rome.[cm] [footnote cm: mr. warren upham, in the bulletin of the geological society of america, vol. ii, p. .] a study of these lines of temporary drainage during the glacial period sheds much light upon the long lines of gravel ridges running parallel with the shores of lake erie and lake ontario. south of lake erie a series of four ridges of different elevations can be traced. in lorain county, ohio, the highest of these is feet above the lake; the next feet; the next feet; and the lower one feet, which would make them respectively , , , and feet above tide. these gravel ridges are evidently old beach lines, and indicate the different levels up to which the water was held by ice-obstructions across the various outlets of the drainage valley. the material in the ridges is water-worn and well assorted, and in coarseness ranges from fine sand up to pebbles several inches in diameter. the predominant material in them is of local origin. where the rocks over which they run are sandstone, the material is chiefly sand, and where the outcropping rock is shale, the ridges consist chiefly of the harder nodules of that formation which have successfully resisted the attrition of the waves. ordinarily these ridges are steepest upon the side facing the lake. according to mr. upham, who has driven over them with me, the lake erie ridges correspond, both in general appearance and in all other important respects, to those which he has so carefully surveyed around the shores of the ancient lake agassiz in minnesota and manitoba, an account of which will be given a little farther on in this chapter. [illustration: fig. .--section of the lake ridges near sandusky, ohio.] we are not permitted, however, to assume that there have been no changes of level since the deposition of these beaches surrounding the ancient glacial lake erie-ontario. on the contrary, there appears to have been a considerable elevation towards the east and northeast in post-glacial times. the highest ridge south of lake erie, which at fort wayne is about feet high, is now about feet in lorain county. the second of the ridges above-mentioned, which is about feet above tide at cleveland, ohio, rises to feet where the last traces of it have been discovered at hamburg, n. y. the third ridge, which is feet at cleveland, has risen to the height of feet at crittenden, about one hundred miles to the east of buffalo, n. y. a similar eastern increase of elevation is discoverable in the main ridge surrounding lake ontario. what professor spencer calls the iroquois beach, which is feet above tide at hamilton, ontario, has risen to a height of feet near syracuse, n. y.; while farther to the northeast, in the vicinity of watertown, it is upwards of feet above tide. there is also a similar northward increase of elevation in the beaches surrounding the higher lands of ontario eastward of lake huron and georgian bay. all this indicates that at the close of the glacial period there was a subsidence of several hundred feet in the area of greatest ice-accumulation lying to the east and north of the great lake region. the formation of these ridges occurred during that period of subsidence. the re-elevation which followed the disappearance of the ice of course carried with it these ridges, and brought them to their present position.[cn] [footnote cn: see spencer, in bulletin of the geological society of america, vol. ii, pp. - .] in returning to consider more particularly the remarkable gorge joining the minnesota with the red river of the north, we are brought to the largest of the glacial lakes of this class, and to the typical place in america in which to study the temporary changes of drainage produced by the ice itself daring the periods both of its advance and of its retreat. [illustration: fig. .--map showing the stages of recession of the ice in minnesota as described in the text (upham).] by turning to our general map of the glaciated region of the united states,[co] one can readily see the relation of the valley between lake traverse and big stone lake to an area marked as the bed of what is called lake agassiz. during the glacial period brown's valley, the depression joining these two lakes, was the outlet of an immense body of water to the north, whose natural drainage was towards hudson bay or the arctic ocean, but which was cut off, by the advancing ice, from access to the ocean-level in that direction, and was compelled to seek an exit to the south. [footnote co: see page .] thus for a long period the present minnesota river valley was occupied by a stream of enormous dimensions, and this accounts for the great size of the trough--the present minnesota being but an insignificant stream winding about in this deserted channel of the old "father of waters," and having as much room as a child of tender age would have in his parent's cast-off garments. this glacial stream has been fittingly named river warren, after general warren, who first suggested and proved its existence, and so we have designated it on the accompanying map of minnesota. lake traverse is fifteen miles long, and the water is nowhere more than twenty feet deep. big stone lake is twenty-six miles long, and of about the same depth. brown's valley, which connects the two, is five miles long, and the lakes are so nearly on a level that during floods the water from lake traverse sometimes overflows and runs to the south as well as to the north. [illustration: fig. .--glacial terrace near the boundary of the glaciated area, on raccoon creek, a tributary of the licking river, in granville, licking county, ohio. height about fifty feet.] the trough occupied by these lakes and valley is from one mile to one mile and a half in width and about feet in depth. if we had been permitted to stand upon the bluffs overlooking it during the latter part of the glacial period, we should have seen the whole drainage of the north passing by our feet on its way to the gulf of mexico. as lie follows down the valley of the minnesota river, the observant traveller, even now, cannot fail to see in the numerous well-preserved gravel terraces the high-water marks of that stream when flooded with the joint product of the annual precipitation over the vast area to the north, and of the still more enormous quantities set free by the melting of the western part of the great laurentide glacier. numerous other deserted water-ways in the northwestern part of the valley of the mississippi have been brought to light in the more recent geological surveys, both in the united states and in canada. during a considerable portion of the glacial period the saskatchewan, the assiniboine, the pembina, and the cheyenne rivers, whose present drainage is into the red river of the north, were all turned to the south, and their temporary channels can be distinctly traced by deserted water-courses marked by lines of gravel deposits.[cp] [footnote cp: for further particulars, see ice age, pp. _et seq._] in dakota, professor j. e. todd has discovered large deserted channels on the southwestern border of the glaciated region near the missouri river, where evidently streams must have flowed for a long distance in ice-channels when the ice still continued to occupy the valley of the james river. from these channels of ice in which the water was held up to the level of the missouri coteau the water debouched directly into channels with sides and bottom of earthy material, which still show every mark of their former occupation by great streams.[cq] [footnote cq: for particulars, see ice age, p. .] in minnesota, also, there is abundant evidence that while the northeastern part of the valley from mankato to st. paul was occupied by ice, the drainage was temporarily turned directly southward across the country through union slough and blue earth river into the head-waters of the des moines river in iowa. _ancient river terraces._ the interest of the whole inquiry respecting the relation of man to the glacial period in america concentrates upon these temporary lines of southern drainage. wherever they existed, the swollen floods of the glacial period have left their permanent marks in the deposition of extensive gravel terraces. the material thus distributed is derived largely from the glacial deposits through which they run and out of which they emerge. while the height of the terraces depended upon various conditions which must be studied in detail, in general it may be said that it corresponds pretty closely with the extent of the area whose drainage was turned through the channel during the prevalence of the ice. the height of the terraces and the coarseness of the material seem also to have been somewhat dependent upon the proximity of their valleys to the areas of most vigorous ice-action, and this, in turn, seems to lie in the rear of the moraines which president chamberlin has attributed to the second glacial epoch. southward from this belt of moraines the terraces uniformly and gradually diminish both in height and in the coarseness of their gravel, until they finally disappear in the present flood-plain of the mississippi river. [illustration: fig. .--ideal section across a river-bed in drift region: _b b b_, old river-bed; _r_, the present river; _t t_, upper or older terraces; _t' t'_, lower terraces.] an interesting illustration of this principle is to be observed in the continuous valley of the alleghany and ohio rivers. the trough of this valley was reached by the continental glacier at only a few points, the ice barely touching it at salamanca, n. y., franklin, pa., and cincinnati, ohio. but throughout its whole length the ice-front was approximately parallel to the valley, and occupied the head-waters of nearly all its tributaries. now, wherever tributaries which could be fed by glacial floods, enter the trough of the main stream, they brought down an excessive amount of gravel, and greatly increased the size of the terrace in the trough itself, and from the mouth of each such tributary to that of the next one below there is a gradual decrease in the height of the terrace and in the coarseness of the material. this law is illustrated with special clearness in pennsylvania between franklin and beaver. franklin is upon the alleghany river, at the last point where it was reached directly by the ice. below this point no tributary reaches it from the glaciated region, and none such reaches the ohio after its junction with the alleghany until we come to the mouth of beaver creek, about twenty-five miles below pittsburg. but at this point the ohio is joined by a line of drainage which emerges from the glaciated area only ten or twelve miles to the north, and whose branches occupy an exceptionally large glaciated area. accordingly, there is at beaver a remarkable increase in the size of the glacial terrace on the ohio. in the angle down-stream between the beaver and the ohio there is an enormous accumulation of granitic pebbles, many of them almost large enough to be called boulders, forming the delta terrace, upon which the city is built and rising to a height of feet above the low-water mark in the ohio. in striking confirmation of our theory, also, the terrace in the ohio valley upon the upper side of beaver creek is composed of fine material, largely derived from local rocks and containing but few granitic pebbles. from the mouth of beaver creek, down the ohio, the terrace is constant (sometimes upon one side of the river and sometimes upon the other), but, according to rule, the material of which it is composed gradually grows finer, and the elevation of the terrace decreases. according to rule, also, there is a notable increase in the height of the terrace below each affluent which enters the river from the glaciated region. this is specially noticeable below marietta, at the mouth of the muskingum, whose head-waters drain an extensive portion of the glaciated area. from the mouth of the little beaver to this point the tributaries of the ohio are all small, and none of them rise within the glacial limit. hence they could contribute nothing of the granitic material which enters so largely into the formation of the river terrace; but below the mouth of the muskingum the terrace suddenly ascends to a height of nearly one hundred feet above low-water mark. again, at the mouth of the scioto at portsmouth, there is a marked increase in the size of the terrace, which is readily accounted for by the floods which came down the scioto valley from the glaciated region. the next marked increase is at cincinnati, just below the mouth of the little miami, whose whole course lay in the glaciated region, and whose margin is lined by very pronounced terraces. at cincinnati the upper terrace upon which the city is built is feet above the flood-plain. twenty-five miles farther down the river, near lawrenceburg, these glacial terraces are even more extensive, the valley being there between three and four miles wide, and being nearly filled with gravel deposits to a height of feet above the flood-plain. below this point the terraces gradually diminish in height, and the material becomes finer and more water-worn, until it merges at last in the flood-plain of the mississippi. the course of the wabash river is too long to permit it to add materially to the size of the terraces which characterise the broader valley of the ohio below the illinois line. it is in terraces such as these just described that we find the imbedded relics of man which definitely connect him with the great ice age. these have now been found in the glacial terraces of the delaware river at trenton, n. j.; in similar terraces in the valley of the tuscarawas river at new comerstown, and in the valley of the little miami at loveland and madisonville, in ohio; on the east fork of white river, at medora, ind.; and still, again, at little falls, in the trough of the mississippi, some distance above minneapolis, minn. i append a list of the points at which various streams from the atlantic ocean to the mississippi river emerge from the glacial boundary, and below which the terraces are specially prominent. of course, with the retreat of the ice, the formation of the terraces continued northward in the glaciated area to a greater or less distance, according to the extent of the valley or to the length of time during which the drainage was temporarily turned into it. these points of emergence are: in the delaware valley, at belvidere, n. j.; in the susquehanna, at beach haven, pa.; in the conewango, at ackley, warren county; in oil creek, above titusville: in french creek, a little above franklin; in beaver creek, at chewtown, lawrence county; on the middle fork of little beaver, near new lisbon, ohio; on the east branch of sandy creek, at east rochester, columbiana county; on the nimishillin, at canton, stark county; on the tuscarawas, at bolivar; on sugar creek, at beech city; on the killbuck, at millersburg, holmes county; on the mohican, near the northeast corner of knox county; on the licking river, at newark; on jonathan creek, perry county; on the hocking, at lancaster; on the scioto, at hopetown, just above chillicothe; on paint creek, and its various tributaries, between chillicothe and bainbridge; and on the wabash, above new harmony, ind.; to which may be added the ohio river itself, at its junction with the miami, near lawrenceburg. another class of terraces having most interesting connection with the glacial period is found in the arid basins west of the rocky mountains. over wide areas in utah and nevada the evaporation now just balances the precipitation, and all the streams disappear in shallow bodies of salt water of moderate dimensions, of which great salt lake in utah, and mono, pyramid, and north carson lakes in nevada, are the most familiar examples. these occupy the lowest sinks of enclosed basins of great depth. but there is abundant evidence that in consequence of the increased precipitation and diminished evaporation of the glacial period one of these basins was filled to the brim and the other to a depth of several hundred feet. these former enlargements have been named after the first explorers of the region, captains lahontan and bonneville, and are shown on the accompanying sketch map by the shading surrounding the existing lakes. lake lahontan has been carefully studied by mr. i. c. russell, and has been found to extend from the boundary of oregon to latitude ° ' south, a distance of two hundred and sixty miles. the central pacific railroad runs through its dried-up bed from golconda to wadsworth, a distance of one hundred and sixty-five miles. the terraces of the former lake are distinctly traceable at a height of feet above the present level of lake mono. lake bonneville, whose present representative is great salt lake, is the subject of a recent monograph by mr. g. k. gilbert, from which it appears that this ancient body of water occupied , square miles--an area about ten times that of the present lake. at the time of its maximum extension its depth was , feet, while great salt lake ranges only from fifteen to fifty feet in depth. the pass through which the discharge finally took place is at red rock, on the utah and northern railroad, at the head of cache valley on the south and the lower part of marsh creek valley on the north. during the long period preceding and accompanying the gradual rise of water in the utah basin to the level of the highest terrace, marsh creek (the upper portion of which comes from the mountains on the east and turns at right angles) had been at work depositing a delta of loose material in the col which separates the two valleys. this deposit rested upon a stratum of limestone at the bottom of the pass, and covered it with sand, clay, and gravel to a depth of feet. thus, when the water was approaching its upper level, the only barrier to prevent its escape was this unstable accumulation of loose material upon top of the rock. it would have required, therefore, no prophet's eye to predict that the way was preparing for a tremendous _débâcle_. [illustration: fig. .--map of the quaternary lakes. bonneville and lahontan (after gilbert and russell).] the critical point at length was reached. after remaining nearly at the elevation of the pass for a considerable period, during which the , -foot shore-line was formed, the crisis came when the water began to flow northward towards snake river. once begun in such loose material, the channel rapidly enlarged until soon a stream equal to niagara, and at times probably much larger, was pouring northward through the valley heretofore occupied by the insignificant rivulets of marsh creek and the port neuf. it is impossible to tell how rapidly the loose barrier wore away, but there is abundant evidence in the valley below that not only the present channel of the lower part of marsh creek, but the whole bottom of the valley for a mile or more in width, was for a considerable time covered by a rapid stream from ten to twenty feet in depth, and descending at the rate of thirteen feet to the mile. the continuance of this flood was dependent upon the amount of water to be discharged, which, as we have seen, was that contained in an area of , square miles, with a depth of feet. a stream of the size of niagara would occupy about twenty-five years in the discharge of such a mass, and this may fairly be taken as a measure of the time through which it lasted. when the loose material lying above the strata of limestone in red rock pass had been washed away, the lake then continued at that level for an indefinite period, with an overflow regulated by the annual precipitation of the drainage basin. this stage of the lake, during which it occupied , square miles and was feet above its present level, is also marked by an extensive and persistent shore-line all around the basin. but, finally, the balance again turned when the evaporation exceeded the precipitation, and the vast body of water has since dwindled to its present insignificant dimensions. my own interest in this discovery of mr. gilbert is enhanced by the explanation it gives of a phenomenon in the snake river valley which i was unable to solve when on the ground in . the present railroad town of pocatello is situated just where this flood emerged from the narrower valley of marsh creek and the port neuf, and spread itself out upon the broad plain of the snake river basin. the southern edge of the plain upon which the city is built is a vast boulder-bed covered with a thin stratum of sand and gravel. everywhere, in sinking wells and digging ditches on the vacant lots and in the streets of the city, water-worn boulders of a great variety of material and sometimes three or four feet in diameter are encountered. i was debarred from regarding this as a terminal moraine, both by the water-worn character of the boulders and by the absence of any sign of ice-action in the surrounding mountains, and i was equally debarred from attributing it to any ordinary stream of water, both by the size of the boulders and the fact that for a mile or more up the port neuf valley there is an intervale, forty or fifty feet below the surface at pocatello, and occupying the whole width of the valley, in which there is only gravel and fine sand, through which the present port neuf pursues a meandering course. the upper end of this short intervale is bounded by the terminus of a basaltic stream which had flowed down the valley and filled it to a considerable depth, but had subsequently been much eroded by violent water-action. in the light of mr. gilbert's discoveries, however, everything is clear. the tremendous _débâcle_ which he has brought within the range of scientific vision would naturally produce just the condition of things which is so puzzling at pocatello. coming down through the restricted channel with sufficient force to roll along boulders of great size and to clear them all out from the upper portion of the valley, the torrent would naturally deposit them where the current was first checked, a mile below the lava cliffs. the plunge of the water over these cliffs would keep a short space below clear from boulders, and the more moderate stream of subsequent times would fill in the depression with the sand and gravel now occupying it. what other effects of this remarkable outburst may be traced farther down in the snake river valley i cannot say, but it will be surprising if they do not come to light and help to solve some of the many geological problems yet awaiting us in this interesting region. it should have been said that during the formation of the -foot, or so-called provo shore-line, glaciers descended from the cañons on the west flank of the wahsatch mountains, and left terminal moraines to mark the coincidence of the glacial period with that stage of the enlargement of the lake. evidences of a similar coincidence are to be found on the high-level terraces surrounding lake mono, to which glaciers formerly descended from the western flanks of the sierra nevada. the ancient shore-lines surrounding lakes bonneville and lahontan bear evidence also of various other episodes in the glacial period. evidently there were two periods of marked increase in the size of the lakes, with an arid period intervening. during the first rise the level of bonneville attained to within ninety feet of the second, and numerous beaches were formed, and a large amount of yellow clay deposited. then it seems to have been wholly evaporated, while its soluble mineral matter was precipitated, and so mingled with silt that it did not readily redissolve during the second great rise of water. partly on this account, and partly through the influence of the outlet into the snake river, the lake was nearly fresh during its second enlargement. _european facts._ in chapter vi it came in place to mention many of the facts connected with the influence of the glacial period upon the drainage systems of europe. we there discussed briefly the probable influence of the ice-obstructions that extended across the mouths of the dwina, the vistula, the oder, the elbe, the weser, and the rhine. the drainage of the obstructed rivers in russia was perhaps turned southward into the caspian and black seas, and then assisted in forming the fertile soil of the plains in the southern part of that empire. the obstructed drainage of the german rivers was probably turned westward in front of the ice through the straits of dover or across the southern part of england. this was during the climax of the glacial period; but later, according to dawkins, during a period in which the land of the british isles stood about feet above its present level, the streams of the eastern coast--namely, "the thames, medway, humber, tyne, and others, joined the rhine, the weser, and the elbe, to form a river flowing through the valley of the ocean. in like manner, the rivers of the south of england and of the north of france formed a great river flowing past the channel islands due west into the atlantic, and the severn united with the rivers of the south of ireland; while those to the east of ireland joined the dee, mersey ribble, and lune, as well as those of western scotland, ultimately reaching the atlantic to the west of the hebrides. the water-shed between the valleys of the british channel and the north sea is represented by a ridge passing due south from folkestone to dieppe, and that between the drainage area and the severn and its tributaries on the one hand, and of the irish channel on the other, by a ridge from holyhead westward to dublin. "this tract of low, undulating land which surrounded britain and ireland on every side consisted not merely of rich hill, valley, and plain, but also of marsh-land studded with lakes, like the meres of norfolk, now indicated by the deeper soundings. these lakes were very numerous to the south of the isle of wight and off the coast of norfolk and suffolk."[cr] [footnote cr: early man in britain, p. .] the evidence first regarded by scientific men to be demonstrative of the formation of extensive lakes during the glacial period by the direct influence of ice-dams exists in the parallel roads of glen roy in scotland. [illustration: fig. .--parallel roads of glen roy.] according to the description of sir charles lyell, "glen roy is situated in the western highlands, about ten miles north of fort william, near the western end of the great glen of scotland, or caledonian canal, and near the foot of the highest of the grampians, ben nevis. throughout nearly its whole length, a distance of more than ten miles, three parallel roads or shelves are traced along the steep sides of the mountains, each maintaining a perfect horizontality, and continuing at exactly the same level on the opposite sides of the glen. seen at a distance they appear like ledges, or roads, cut artificially out of the sides of the hills; but when we are upon them, we can scarcely recognize their existence, so uneven is their surface and so covered with boulders. they are from ten to sixty feet broad, and merely differ from the side of the mountain by being somewhat less steep. "on closer inspection, we find that these terraces are stratified in the ordinary manner of alluvial or littoral deposits, as may be seen at those points where ravines have been excavated by torrents. the parallel shelves, therefore, have not been caused by denudation, but by the deposition of detritus, precisely similar to that which is dispersed in smaller quantities over the declivities of the hills above. these hills consist of clay-slate, mica-schist, and granite, which rocks have been worn away and laid bare at a few points immediately above the parallel roads. the lowest of these roads is about feet above the level of the sea, and the next about feet higher, and the third feet above the second. there is a fourth shelf, which occurs only in a contiguous valley called glen gluoy, which is twelve feet above the highest of all the glen roy roads, and consequently about , feet above the level of the sea. one only, the lowest of the three roads of glen roy, is continued through glen spean, a large valley with which glen roy unites. as the shelves, having no slope towards the sea like ordinary river terraces, are always at the same absolute height, they become continually more elevated above the river in proportion as we descend each valley; and they at length terminate very abruptly, without any obvious cause, or any change either in the shape of the ground or in the composition or hardness of the rocks."[cs] [footnote cs: antiquity of man, pp. , .] early in his career charles darwin studied these ancient beaches, and ascribed them to the action of the sea during a period of continental subsidence. in this view he was supported by the majority of geologists until the region was visited by agassiz, who saw at once the true explanation. if these were really sea-beaches, similar deposits should be found at the same elevation on other mountains than those surrounding glen roy. their absence elsewhere points, therefore, to some local cause, which was readily suggested to the trained eye of one like agassiz, then fresh from the study of alpine glaciers, who saw that these beaches were formed upon the margin of temporary lakes, held back during the glacial period (as the merjelen see now is) by a glacier which came out of one glen and projected itself directly across the course of another, and thus obstructed its drainage. the glacier of glen spean had pushed itself across glen roy, as the great aletsch glacier in switzerland now pushes itself across the little valley behind the eggishorn. chapter viii. relics of man in the glacial period. _in glacial terraces of the united states._ although the first clear evidence of glacial man was discovered in europe, the problem is so much simpler on the western continent that we shall find it profitable to study the american facts first. we will therefore present a summary of them at once, and then proceed to the more obscure problems of european archæology. the first definite discovery of human relics clearly connected with, glacial deposits in america, and of the same age with them, was made by dr. c. c. abbott, at trenton, n. j., in the year . the city of trenton is built upon a delta terrace about three miles wide which occurs at the head of tide-water on the delaware river. this terrace bears every mark of having been deposited by a torrential stream which came down the valley during the closing period of the great ice age. the material of which the terrace consists is all water-worn. according to the description of professor n. s. shaler: [illustration: fig. .--the glaciated portion is shaded. the shading on the lehigh and delaware rivers indicates glacial terraces, which are absent from the schuylkill.] "the general structure of the mass is neither that of ordinary boulder-clay nor of stratified gravels, such as are formed by the complete rearrangement by water of the elements of simple drift-deposits. it is made up of boulders, pebbles, and sand, varying in size from masses containing one hundred cubic feet or more to the finest sand of the ordinary sea-beaches. there is little trace of true clay in the deposit; there is rarely enough to give the least trace of cementation to the masses. the various elements are rather confusedly arranged; the large boulders not being grouped on any particular level, and their major axes not always distinctly coinciding with the horizon. all the pebbles and boulders, so far as observed, are smooth and water-worn, a careful search having failed to show evidence of distinct glacial scratching or polishing on their surfaces. the type of pebble is the subovate or discoidal, and though many depart from this form, yet nearly all observed by me had been worn so as to show that their shape had been determined by running water. the materials comprising the deposit are very varied, but all i observed could apparently with reason be supposed to have come from the extensive valley of the river near which they lie, except perhaps the fragments of some rather rare hypogene rocks." [illustration: fig. .--palæolith found by abbott in new jersey, slightly reduced.] a conclusive proof of the relation of this trenton delta terrace to the glacial period is found in the fact that the gravel deposit is continuous with terraces extending up the trough of the valley of the delaware to the glaciated area and beyond. as, however, the descent of the river-bed is rapid (about four feet to the mile) from the glacial border down to tide-water, the terrace is not remarkably high, being only about fifteen or twenty feet above the present flood-plain. but it is continuous, and similar in composition with the great enlargement in the delta at trenton. without doubt, therefore, the deposit represents the overwash gravel of the glacial period. fortunately for science, dr. c. c. abbott, whose tastes for archæological investigations were early developed, had his residence upon the border of this glacial delta terrace at trenton, and as early as began to find rough-stone implements of a peculiar type in the talus of the bank where the river was undermining the terrace. in turning his attention to the numerous fresh exposures of gravel made by railroad and other excavations during the following year, he found several of the implements in undisturbed strata, some of which were sixteen feet below the surface. since that time he has continued to make discoveries at various intervals. in he had found four hundred implements of the palæolithic type at trenton, sixty of which had been taken from recorded depths in the gravel, two hundred and fifty from the talus at the bluff facing the river, and the remainder from the surface, or derived from collectors who did not record the positions or circumstances under which they were found. [illustration: fig. .--section across the delaware river at trenton. new jersey: _a_, _a_, philadelphia red gravel and brick-clay (mcgee's columbia deposit); _b_. _b_, trenton gravel, in which the implements are found: _c_, present flood-plain of the delaware river (after lewis). (from abbott's primitive industry.)] the material from which the implements at trenton are made is argillite--that is, a clay slate which has been so metamorphosed as to be susceptible of fracture, almost like flint. it is, however, by no means capable of being worked into such delicate forms as flint is. but as it is the only material in the vicinity capable of being chipped, prehistoric men of that vicinity were compelled to make a virtue of necessity and use the inferior material. of all the implements found by dr. abbott in the gravel, only one was flint; while upon the surface innumerable arrow-heads of flint have been found. the transition, also, in the type of implements is as sudden as that in the kind of material of which they are made. below the superficial deposit of black soil, extending down to the depth of about one foot, the modern indian flint implements entirely disappear, and implements of palæolithic type only are found. [illustration: fig. .--section of the trenton gravel in which the implements described in the text are found. the shelf on which the man stands is made in process of excavation. the gravel is the same above and below (photograph by abbott).] [illustration: fig. .--face view of argillite implement, found by dr. c. c. abbott, in , at trenton, new jersey, in gravel, three feet from face of bluff, and twenty-two feet from the surface (no. , ) (putnam).] in the year , after i had traced the glacial boundary westward from the delaware river, across the states of pennsylvania, ohio, and indiana, i was struck with the similarity between the terrace at trenton and numerous terraces which i had attributed to the glacial age in ohio and the other states. it adds much to the interest of subsequent discoveries to note that in , in my report to the western reserve historical society upon the glacial boundary of ohio, i wrote as follows: [illustration: fig. .--argillite implement found by dr. c. c abbott, march, , at a. k. rowan's farm, trenton, new jersey, in gravel sixteen feet from surface: a, face view; b, side view (no. , ) (putnam).] "the gravel in which they [dr. abbott's implements] are found is glacial gravel deposited upon the banks of the delaware when, during the last stages of the glacial period, the river was swollen with vast floods of water from the melting ice. man was on this continent at that period when the climate and ice of greenland extended to the mouth of new york harbor. the probability is, that if he was in new jersey at that time, he was also upon the banks of the ohio, and the extensive terrace and gravel deposits in the southern part of our state should be closely scanned by archæologists. when observers become familiar with the rude form of these palæolithic implements, they will doubtless find them in abundance. but whether we find them or not in this state [ohio], if you admit, as i am compelled to do, the genuineness of those found by dr. abbott, our investigation into the glacial phenomena of ohio must have an important archæological significance, for they bear upon the question of the chronology of the glacial period, and so upon that of man's appearance in new jersey." [illustration: fig. .--chipped pebble of black chert, found by dr. c. l. metz. october, , at madisonville, ohio, in gravel eight feet from surface under clay: _a_, face view; _b_, side view.] the expectation of finding evidence of preglacial man in ohio was justified soon after this (in ), when dr. c l. metz, while co-co-operating with professor f. w. putnam, of the peabody museum, cambridge, mass., in field work, discovered a flint implement of palæolithic type in undisturbed strata of the glacial terrace of the little miami river, near his residence at madisonville, ohio. in dr. metz found another implement in the terrace of the same river, at loveland, about twenty-five miles farther up the stream. the implement at madisonville occurred eight feet below the surface, and about a mile back from the edge of the terrace; while that at loveland was found in a coarser deposit, about a quarter of a mile back from the present stream, and thirty feet below the surface. mastodon-bones also were discovered in close proximity to the implement at loveland. [illustration: fig. .] interest in these investigations was still further increased by the report of mr. hilborne t. cresson, of philadelphia, that in , with my map of the glaciated region in hand, he had found an implement of palæolithic type in undisturbed strata of the glacial terrace bordering the east branch of white river, near the glacial boundary at medora, jackson county, ind. the terrace was about fifty feet above the flood-plain of the river. later still, in october, , mr. w. c. mills, of newcomerstown, tuscarawas county, ohio, found in that town a finely shaped flint implement sixteen feet below the surface of the terrace of glacial gravel which lines the margin of the tuscarawas valley.[ct] mr. mills was not aware of the importance of this discovery until meeting with me some months later, when he described the situation to me, and soon after sent the implement for examination. in company with judge c. c. baldwin, president of the western reserve historical society, and several others, a visit was made to mr. mills, and we carefully examined the gravel-pit in which the implement occurred, and collected evidence which was abundant to corroborate all his statements. the implement in question is made from a peculiar flint which is found in the lower mercer limestone, of which there are outcrops a few miles distant, and it resembles in so many ways the typical implements found by boucher de perthes, at abbeville, that, except for the difference in the material from which it is made, it would be impossible to distinguish it from them. the similarity of pattern is too minute to have originated except from imitation. [footnote ct: for typical section of a glacial terrace in ohio, see p. .] [illustration: fig. .--the smaller is the palæolith from newcomerstown, the larger from amiens (face view), reduced one half in diameter.] in , a year after the discoveries by dr. abbott in new jersey, some rude quartz implements were discovered by professor n. h. winchell in the glacial terraces of the upper mississippi, in the vicinity of little falls, morrison county, minn. this locality was afterwards more fully explored by miss franc e. babbitt, who succeeded in finding so large a number of the implements as to set at rest all question concerning their human origin. according to mr. warren upham, the glacial flood-plain of the mississippi is here about three miles wide, with an elevation of from twenty-five to thirty feet above the river. it is in a stream near the bottom of this glacial terrace that the most of miss babbitt's discoveries were made, and mr. upham has pretty clearly shown that the gravel of the terrace overlying them was mostly deposited while the ice-front was still lingering about sixty miles farther north, in the vicinity of itasca lake.[cu] [footnote cu: for a general map, see p. ; also p. .] [illustration: fig. .--edge view of the preceding.] [illustration: fig. .--section across the mississippi valley at little falls, minnesota, showing the stratum in which chipped quartz fragments were found by miss f. e. babbitt, as described in the text (upham).] up to this time the above are all the instances in which the relics of man are directly and indubitably connected with deposits of this particular period east of the rocky mountains. probably it is incorrect to speak of these as preglacial, for the portion of the period at which the deposits incorporating human relics were made is well on towards the close of the great ice age, since these terraces were, in some cases, and may have been in all cases, deposited after the ice-front had withdrawn nearly, if not quite, to the water-shed of the st lawrence basin. it may be difficult to demonstrate this with reference to the gravel deposits at trenton, madisonville, and medora, but it is evident at a glance in the case of newcomerstown and little falls. that the implement-bearing gravel of trenton, n. j., belongs to the later stages of the glacial period is evident from its relation to what professor h. carvill lewis called "the philadelphia red gravel and brick-clay," but which, from its large development in the district of columbia at washington, is called by mr. mcgee the "columbia deposit." the city of philadelphia is built upon this formation in the delaware valley, and the brick for its houses is obtained from it; the cellar of each house ordinarily furnishing clay enough for its brick walls. this clay is of course a deposit in comparatively still water, which would imply deposition during a period of land subsidence. but that it was ice-laden water which flooded the banks is shown by the frequent occurrence of large blocks of stone in the deposits, such as could have been transported only in connection with floating ice. the boulders in the columbia formation clearly belong to the individual river valleys in which they are found, and doubtless are to be connected with the flooded condition of those valleys when, by means of a northerly subsidence, the gradient of the streams was considerably less than now. [illustration: fig. .--quartz implement, found by miss f. e. babbitt, , at little falls, minnesota, in modified drift, fifteen feet below surface: _a_, face view; _b_, profile view. the black represented on the cut is the matrix of the quartz vein (no. , ) (putnam).] there is some difference of opinion in respect to the extent of this subsidence, and, indeed, respecting the height attained by the philadelphia brick-clay, or mcgee's columbia deposit. professor lewis (whose residence was at philadelphia, and who had devoted much time to field observations) insisted that the deposit could not be found higher than from to feet above the immediate flood-plain of the river valleys where they occur. but, without entering upon this disputed question, it is sufficient to consider the bearing of the facts that are accepted by all--namely, that towards the close of the glacial period there was a marked subsidence of the land on the eastern coast of north america, increasing towards the north. fully to comprehend the situation, we need to bring before the mind some of the indirect effects of the glacial period in this region. the most important of these was the necessary projection of subglacial conditions over a considerable belt of territory to the south of that actually reached by glacial ice; so that, while there are no clear indications of the existence of local glaciers in the appalachian mountains south of the central part of pennsylvania, there are many indications of increased snow-fall upon the mountains, connected with prolonged winters and with a great increase of spring floods and ice-gorges upon the annual breaking up of winter. these facts have been stated in detail by mr. mcgee,[cv] from whose report it appears that, on the potomac at washington, the surface of the columbia deposit is feet above tide, and that the deposit itself contains many boulders, some of which are as much as two or three feet in diameter. these are mingled with the gravel in such a way as to show that they must have been brought down by floating ice from the head-waters of the potomac when the winters were much more severe than now. that this deposit is properly the work of the river is shown by the entire absence of marine shells. [footnote cv: seventh annual report of the united states geological survey for and , pp. - .] according to mr. mcgee, also, there is a gradual decrease in the height of these delta terraces of the columbia period as they recede from the glacial boundary--that at the mouth of the susquehanna being feet, that of the potomac feet, that on the rappahannock , that on the james , and that on the roanoke ; while the size of the transported boulders along the streams also gradually diminishes in the same order. during the columbia period the susquehanna river transported boulders fifty times the size now transported, while the potomac transported them only up to twenty times, the rappahannock only ten times, the james only five, and the roanoke only two or three times the size of those now transported. this progressive diminution, both in the extent of the deposit and in the coarseness of the material deposited by these rivers at about the time of the maximum portion of the glacial period, is what would naturally be expected under the conditions supposed to exist in connection with the great ice age, and is an important confirmation of the glacial theory. that the period of subsidence and more intense glacial conditions during which the columbia deposits took place, preceded, by a long interval, the deposition of the gravel terraces at trenton, n. j., and the analogous deposits in the mississippi valley where palæolithic implements have been found, is evident enough. the trenton gravel was deposited in a recess in the columbia deposit which had been previously worn out by the stream. indeed, in every place where opportunity offers for direct observation the trenton gravel is seen to be distinctly subsequent to the other. it was not _buried by_ the philadelphia red gravel and brick-clay, but to a limited degree overlies and _buries_ it. the data for measuring the absolute length of time between these two stages of the glacial period are very indefinite. mr. mcgee, however, supposes that since the columbia period a sufficient time has elapsed for the falls of the susquehanna to recede more than twenty miles and for those of the potomac eighteen miles, and this through a rock which is exceedingly obdurate. but, in channels opening, as these do, freely outward, it is difficult to tell in what epochs the erosion has been principally performed, since there are no buried channels, as in the glaciated area, enabling us to determine whether or not much of the eroding work of the river may have been accomplished in preglacial times. the lapse of time which, upon the least calculation, separates the columbia epoch from the trenton, gives unusual importance to any discovery of palæolithic implements which may be made in the earlier deposits. we are bound, therefore, to consider with special caution the reported discovery of an implement in these deposits at claymont, delaware. the discovery was made by dr. hilborne t. cresson, on july , , during the progress of an extensive excavation in constructing the baltimore and ohio railroad, nineteen miles south of philadelphia. the implement was from eight to nine feet below the surface. as there is so much chance for error of judgment respecting the undisturbed condition of the strata, and as there was so little opportunity for dr. cresson to verify his conclusion, we may well wait for the cumulative support of other discoveries before building a theory upon it; still, it will be profitable to consider the situation. [illustration: fig. .--argillite implement, found by h. t. cresson, , in baltimore and ohio railroad cut, one mile from claymont, delaware, in columbia gravel, eight to nine feet below the overlying clay bed: _a_, face view; _b_, side view (no. , ) (putnam).] both mr. mcgee and myself have visited the locality with dr. cresson, and there can be no doubt that the implement occurred underneath the columbia gravel. the line of demarcation is here very sharp between that gravel and the decomposed strata of underlying gneiss rock, which appears in our illustration as a light band in the middle of the section exposed. some large boulders which could have been moved only in connection with floating ice are found in the overlying deposit near by. this excavation is about one mile and a half west of the delaware river, and about feet above it, being nearly at the uppermost limit of the columbia deposit in that vicinity. [illustration: fig. .--general section of baltimore and ohio cut, near claymont, delaware, where mr. cresson found palæolithic implements figured in the text (from photograph by cresson).] the age of these deposits in which implements have been found at claymont and at trenton will be referred to again when we come to the specific discussion of the date of the glacial period. it is sufficient here to bring before our minds clearly, first, the fact that this at claymont is connected with the river floods accompanying the ice at its time of maximum extension, and when there was a gradually increasing or differential depression of the country to an unknown extent to the northward. two radically different theories are presented to account for the deposits variously known as the columbia gravel and the philadelphia brick-clay. mr. mcgee, in the monograph above referred to, supposes them to have been deposited during a period of a general subsidence of the coast-line; so that they took place at about tide-level. mr. upham, on the other hand, supposes them to have been deposited during the period of general elevation to whose influence he mainly attributes the glacial period itself. in his view much of the shallow sea-bottom adjoining the present shore off from delaware and chesapeake bays was then a land-surface, and the hudson, the delaware, and the susquehanna rivers, coming down from the still higher elevations of the north, flowed through extensive plains so related to the northern areas of elevation that deposition was occurring in their valleys, owing in part to the flooded condition of the streams, in part to the differential elevation, and in part to the superabundance of silt and other _débris_ furnished by the melting ice-sheet in the head-waters of these streams. the deposits of trenton gravel occurred much later, at a time when the ice had melted far back towards the head-waters of the delaware, and after the land had nearly resumed its present relations of level, if indeed it had not risen northward to a still greater relative height. as would be expected from the climatic conditions accompanying the glacial epoch, man's companions in the animal world were very different during the period when the high-level river gravels of america were forming from those with which he is now associated. from the remains actually discovered, either in these gravels or in close proximity to them, we infer that, while the mastodon was the most frequent of the extinct quadrupeds with which man then had to contend in that region, he must have been familiar also with the walrus, the greenland reindeer, the caribou, the bison, the moose, and the musk ox. _in the glacial terraces of europe._ the existence of glacial man in europe was first determined in connection with the high-level river gravels already described in the valley of the somme, situated in picardy in the northern part of france. here in boucher de perthes began to discover rudely fashioned stone implements in undisturbed strata of the gravel terraces, whose connection with the glacial period we have already made clear. but for nearly twenty years his discoveries were ignored by scientific men, although he made persistent efforts to get the facts before them, and published a full account of them with illustrations as early as . some suggested fraud on the part of the workmen; others without examination declared that the gravel must have been disturbed; while others, still, denied altogether the artificial character of the implements. [illustration: fig. .--section across valley of the somme: , peat, twenty to thirty feet thick, resting on gravel, _a_; , lower-level gravels, with elephant-bones and flint implements, covered with river-loam twenty to forty feet thick; , upper-level gravels, with similar fossils covered with loam, in all, thirty feet thick; , upland-loam, five to six feet thick; , eocene-tertiary.] at length, dr. regillout, an eminent physician residing at amiens, about forty miles higher up the somme than abbeville, visited boucher de perthes, and, upon seeing the similarity between the gravel terraces at abbeville and amiens, returned home to look for similar implements in the high-level gravel-pits at st. acheul, a suburb of amiens. almost immediately he discovered flint implements there of the same pattern with those at abbeville, and in undisturbed strata of the gravel terrace, where it rested on the original chalk formation, at a height of feet above the river. in the course of four years, dr. regillout found several hundred of these implements, and in published an illustrated report upon the discoveries. still the scientific world remained incredulous until the years and , when dr. falconer, mr. prestwich, mr. john evans, mr. flower, sir charles lyell, of england, and mm. pouchet and gaudry, of france, visited abbeville and amiens, and succeeded in making similar discoveries for themselves. additional discoveries at st. acheul have continued up to the present time whenever excavations have gone on at the gravel-pits. mr. prestwich estimates that there is an implement to every cubic metre of gravel, and says that he himself has brought away at different times more than two hundred specimens, and that the total number found in this one locality can hardly be under four thousand. "the gravel-beds are on the brow of a hill feet above the river somme," and besides the relics of man contain numerous fluviatile and land shells together with "teeth and bones of the mammoth, rhinoceros, horse, reindeer, and red deer, but not of the hippopotamus,"[cw] bones of the latter animal being found here only in the gravels of the lower terraces, where they are less than thirty feet above the river, and mark a considerably later stage in the erosion of the valley. while many of the implements found at amiens seem to have been somewhat worn and rolled, "others are as sharp and fresh as when first made.... the bedding of the gravel is extremely irregular and contorted, as though it had been pushed about by a force acting from above; and this, together with the occurrence of blocks of tertiary sandstone of considerable size, leads to the inference that both are due to the action of river-ice. in the seine valley blocks of still larger size, and transported from greater distances, are found in gravels of the same age." [footnote cw: prestwich's geology, vol. ii, p. .] "flint implements are found under similar conditions in many of the river-valleys of other parts of france, especially in the neighbourhood of paris; of mons in belgium; in spain, in the neighbourhood of madrid, in portugal, in italy, and in greece; but they have not been discovered in the drift-beds of denmark, sweden, or russia, nor is there any well-authenticated instance of the occurrence of palæoliths in germany."[cx] [footnote cx: prestwich's geology, vol. ii, pp. , .] when once the fact had been established that man was in northern france at the time of the deposition of the high-level gravels of the somme and the seine, renewed attention was directed to terraces of similar age in southern england. one of these is that upon which the city of london is built, and which, according to lyell's description, "extends from above maidenhead through the metropolis to the sea, a distance from west to east of fifty miles, having a width varying from two to nine miles. its thickness ranges commonly from five to fifteen feet."[cy] [footnote cy: antiquity of man, pp. , .] for a long time geologists had been familiar with the fact that these terraces of the thames contain the remains of numerous extinct animals, among which are included the mammoth and a species of rhinoceros. upon directing special attention to the subject, it was found that, at various intervals, the remains of man, also, had been reported from the same deposits. as long ago as mr. conyers discovered a palæolithic implement, in connection with the skeleton of an elephant, at black mary's, near gray's inn lane, london. this implement is preserved in the british museum, and closely resembles typical specimens from the gravel at amiens. other implements of similar character have been found in the valley of the wey near guilford, also in the valley of the darent, near whitstable in kent, and between heme bay and the reculvers. while the exact position of these implements in the gravel had not been so positively noted as in the case of those found at amiens and abbeville, there can be little doubt that man, in company with the extinct animals mentioned, inhabited the valley of the thames at a period when its annual floods spread over the whole terrace-plain upon which the main part of london is built. in the valley of the ouse, however, near bedford, the discovery of palæolithic implements in the gravel terraces connected with the glacial period and in intimate association with bones of the elephant, rhinoceros, hippopotamus, and other extinct animals, has been as fully established as in the valley of the somme. the discoveries here were first made in the year , by mr. james wyatt, in a gravel-pit at biddenham, two miles northwest of bedford. two flint implements were thrown out by workmen in one day from undisturbed strata thirteen feet below the surface, and numerous other specimens have since been found in a similar situation. the valley of the ouse is bordered on either side by sections of a superficial blanket of glacial drift containing many transported boulders of considerable size. the valley is here about two miles wide, and ninety feet deep. the gravel deposit, however, in which the implements were found, is only about thirty feet above the present level of the river, and hence represents the middle period of the work of the river in erosion. another locality in england in which similar discoveries have been made, is at hoxne, about five miles from diss, in suffolk county. like that in the valley of the thames, however, the implements were found a long time before the significance of the discovery was recognized. mr. john frere reported the discovery to the society of antiquaries in , and gave some of the implements both to the society and to the british museum, in whose collections they are still preserved. the implements are of the true palæolithic type, and existed in such abundance, and were so free from signs of wear, that the conclusion seemed probable that a manufactory of them had been uncovered. as many as five or six to the square yard are said to have been found. indeed, their numbers were so great that the workmen "had emptied baskets of them into the ruts of the adjoining road before becoming aware of their value." the deposit in which they are found is situated in the valley of gold brook, a tributary of the waveney. the implements occurred about twelve feet below the surface, in fresh-water deposits, filling a hollow eroded in the glacial deposit covering that part of england. this, therefore, is clearly either of post-glacial or of late glacial age. still another locality in which similar palæolithic implements were found in undisturbed gravel of this same age in eastern england is icklingham, in the valley of the lark, where the situation is quite similar to that already described at bedford, on the ouse. the last place we will stop to mention in england which was visited by palæolithic man, during or soon after the glacial epoch, is to be found in the vicinity of southampton. at this time the isle of wight was joined to the mainland, and not improbably england itself to the continent. the river, then flowing through the depression of the solent and the southampton water, occupied a much higher level than now, leaving terraces along the shore at various places, in which the tools of palæolithic man have been discovered. though these are the best authenticated discoveries connecting man with the glacial period in england, they are by no means the only probable cases. almost every valley of southern england furnishes evidence of a similar but less demonstrative character. _in cave deposits._ the discovery of the remains of man in the high-level river-gravels deposited near the close of the glacial period led to a revision of the evidence which had from time to time been reported connecting the remains of man with those of various extinct animals in cave deposits both in england and upon the continent. _the british isles._ as early as , rev. j. macenery, a roman catholic priest residing near torquay, in devonshire, england, had made some most remarkable discoveries in a cavern at kent's hole, near his home; but, owing to his early death, and to the incredulity of that generation of scientific men, his story was neither credited nor published till . about this time, a new cave having been discovered not far away, at brixham, the best qualified members of the royal society (lyell, phillips, lubbock, evans, vivian, pengelly, busk, dawkins, and sanford) were deputed to see that it was carefully explored. mr. pengelly, who had had twenty years' experience in similar explorations, directed and superintended the work. every portion of the contents was examined with minutest care. kent's hole is " to feet above the level of mean tide, and about feet above the bottom of the valley immediately adjacent."[cz] in one chamber the excavation was about sixty feet square. the contents were arranged in the following order: [footnote cz: dawkins's cave-hunting, p. .] [illustration: fig. .--mouth of kent's hole.] . a surface of dark earth a few inches thick, containing roman pottery, iron and bronze spear-heads, together with polished stone weapons. there were, too, in this stratum bones of cows, goats, and horses, mingled with large quantities of charcoal. . below this was a stalagmite floor from one to three feet thick, formed by the dripping of lime-water from the roof. . under this crust of stalagmite was a compact deposit of red earth, from two to thirteen feet thick.[da] flint implements of various kinds and charcoal were also found at different depths; also an awl, or piercer; a needle with the eye large enough to admit small pack-thread; and three harpoon-heads made out of bone and deer's horn. [footnote da: dawkins's cave-hunting, p. ; lyell's antiquity of man, p. .] . flint implements were also obtained in a conglomerate (breccia) still below this. the fossil bones in this cave belonged to the same species of animals as those discovered in a cave near wells. the brixham cave occurs near the small village of that name, not far from torquay. the entrance to it is about ninety-five feet above high water. its deposits, in descending order, are: . stalagmitic floor from six to twelve or fifteen inches in thickness. . a thin breccia of limestone fragments cemented together by carbonate of lime. this had accumulated about the mouth, so as to fill up the entrance. . a layer of blackish earth about one foot in thickness . a deposit of from two to four feet thick, consisting of clayey loam, mingled with fragments of limestone, from small bits up to rocks weighing a ton. bounded pebbles of other material were also occasionally met with. . shingle consisting of rounded pebbles largely of foreign material. all these strata, except the third, contained fossils of some kind, but the fourth was by far the richest repository. among the bones found are those of the mammoth, the woolly rhinoceros, the horse, the ox, the reindeer, the cave-lion, the cave-hyena, and the cave-bear. associated with these remains a number of worked flints was found. in one place the bones of an entire leg of a cave-bear occurred in such a position as to show that they must have been bound together by the ligaments when they were buried. immediately below these bones a flint implement was found.[db] [footnote db: see pengelly's reports to the devonshire association, .] the hyena's den, at wookey hole, near wells, in somerset, was carefully explored by professor boyd dawkins, who stood by and examined every shovelful of material as it was thrown out. this cave alone yielded specimens of palæolithic art, jaws and teeth of the cave-hyena, of the cave lion, of the cave-bear, of the grizzly bear, of the brown bear, of the wolf, of the fox, of the mammoth, of the woolly rhinoceros, of the horse, of the wild ox, of the bison, of the irish elk, and of the reindeer (jaws and teeth only). in derbyshire numerous caves were explored by professor dawkins at cress well crags, which, in addition to flint implements and the remains of the animals occurring in the brixham cave, yielded the bones of the machairodus, an extinct species of tiger or lion which lived during the tertiary period. the victoria cave, near settle, in west yorkshire, is the only other one in england which we need to mention. in this there were no remains found which could be positively identified as human, but the animal remains in the lower strata of the cave deposit were so different from those in the upper bed as to indicate the great lapse of time which separated the two. this cave is , feet above the sea-level, and there were found in the upper strata of the floor, down to a depth of from two to ten feet, many remains of existing animals. then, for a distance of twelve feet, there occurred a clay deposit, containing no organic remains whatever, but some well-scratched boulders. below this was a third stratum of earth mingled with limestone fragments, at the base of which were numerous remains of the mammoth, rhinoceros, hippopotamus, bison, hyena, etc. one bone occurred which was by some supposed to be human, but by others to have belonged to a bear. this lower stratum is, without much doubt, preglacial, and the thickness of the deposit intervening between it and the upper fossiliferous bed is taken by some to indicate the great lapse of time separating the period of the mammoth and rhinoceros in england from the modern age. the scratched boulders in the middle stratum of laminated clay, would indicate certainly that the material found its way into the cave during the glacial epoch, when ice filled the whole valley of the ribble, which flows past the foot of the hill, and whose bed is feet below the mouth of the cave. in north wales the vale of clwyd contains numerous caves which were occupied by hyenas in preglacial times and with their bones are associated those of the mammoth, the rhinoceros, the hippopotamus, the cave-lion, the cave-bear, and various other animals. flint implements also were found in the cave at cae gwyn, near the village of tremeirchon, on the eastern side of the valley, opposite cefn, and about four miles distant. we have already given an illustration of the cefn cave (see page ). it will be observed that this valley of the clwyd opens to the north, and has a pretty rapid descent to the sea from the welsh mountains, and was in position to be obstructed by the irish sea glacier, so as to have been occupied at times by one of the characteristic marginal lakes of the glacial period. it is evident also that the northern ice prevailed over the welsh ice for a considerable portion of the lower part of the valley; for northern drift is the superficial deposit upon the hills on the sides of the valley up to a height of over feet. from the investigations of mr. c. e. de rance, f. g. s.,[dc] it is equally clear also that the northern drift, which until lately sealed up the entrance of the cave, was subsequent to its occupation by man, and this was the opinion formed by sir archibald geikie, director general of the geological survey of the united kingdom, as the result of special investigations which he made of the matter.[dd] [footnote dc: proceedings of the yorkshire geological society for , pp. - .] [footnote dd: see de ranee, as above, p. ; and article by h. hicks, in quarterly journal of geological society, vol. xlii, p. ; geological magazine, may, , p. .] from the caves in the vale of clwyd as many as teeth of rhinoceros, of horse, of hyena, and of mammoth have been taken. a section of the cave deposits in the cave at cae gwyn is as follows: "below the soil for about eight feet a tolerably stiff boulder-clay, containing many ice-scratched boulders and narrow bands and pockets of sand. below this about seven feet of gravel and sand, with here and there bands of red clay, having also many ice-scratched boulders. the next deposit was a laminated brown clay, and under this was found the bone-earth, a brown, sandy clay with small pebbles and with angular fragments of limestone, stalagmites, and stalactites. during the excavations it became clear that the bones had been greatly disturbed by water action; that the stalagmite floor, in parts more than a foot in thickness, and massive stalactites, had also been broken and thrown about in all positions; and that these had been covered afterwards by clays and sand containing foreign pebbles. this seemed to prove that the caverns, now feet above ordnance datum, must have been submerged subsequently to their occupation by the animals and by man. in dr. hicks's opinion, the contents of the cavern must have been disturbed by marine action during the great submergence in mid-glacial times, and afterwards covered by marine sands and by an upper boulder-clay, identical in character with that found at many points in the vale of clwyd. the paleontological evidence suggests that the deposits in question are not preglacial, but may be equivalent to the pleistocene deposits of our river-valleys."[de] [footnote de: h. b. woodward's geology of england and wales, pp. , ] if the views of professor lewis and mr. kendall are correct concerning the unity of the glacial period in england, the shelly and sandy deposits connected with these clwydian caves at an elevation of feet or more would be explained in connection with the marginal lakes which must have occupied the valley during both the advance and the retreat of the ice-front; the shells having been carried up from the sea-bottom by the ice-movement, after the manner supposed in the case of those at macclesfield and moel tryfaen. if, therefore, the statements concerning the discovery of flint implements in this cae gwyn cave can be relied upon, this is the most direct evidence yet obtained in europe of man's occupation of the island during the continuance of the glacial period. in all these caves it is to be noted that there is a sharp line of demarcation between the strata containing palæolithic implements and those containing only the remains of modern animals. palæolithic implements are confined to the lower strata, which in some of the caves are separated from the upper by a continuous bed of stalagmite, to which reference will be made when discussing the chronology of the glacial period. the remains of extinct animals also are confined to the lower beds. the caves which we have been considering in england are all in limestone strata, and have been formed by streams of water which have enlarged some natural fissures both by mechanical action in wearing away the rocks, and by chemical action in dissolving them. through the lowering of the main line of drainage, caverns with a dry floor are at length left, offering shelter and protection both to man and beast. oftentimes, but not always, some idea of the age of these caverns may be obtained by observing the depth to which the main channel of drainage to which they were tributary has been lowered since their formation. but to this subject also we will return when we come specifically to discuss the chronological question. _the continent._ systematic explorations in the caves of belgium were begun in by dr. schmerling, in the valley of the meuse, near his residence in liége. the meuse is here bordered by limestone precipices or more feet in height. opening out from these rocky walls are the entrances to the numerous caverns which have rendered the region so famous. to get access to the most important of these, dr. schmerling had to let himself down over a precipice by a rope tied to a tree, and then to creep along on all-fours through intricate channels to reach the larger chambers which it was his object to explore. in the cave at engis, on the left bank of the meuse, about eight miles above liége, he found a human skull deeply buried in breccia in company with many bones of the extinct animals previously stated to have been associated with man during the glacial period. this so-called "engis skull" was by no means apelike in its character, but closely resembled that of the average caucasian man. but this established the association upon the continent of man with some of the extinct animals of the glacial period. [illustration: fig. .--engis skull, reduced (after lyell.)] the vicinity of liége has also furnished us another cavern whose contents are of the highest importance, ranking indeed as perhaps the most significant single discovery yet made. the cave referred to is on the property of the count of beauffort, in the commune of spy, in the province of namur in belgium. for the facts relating to it we are indebted to messrs: lohest and fraipont, the former professor of geology and the latter of anatomy in the university of liége. the exploration of the cave was made in , and the full report with illustrations published in the following year in archives de biologie.[df] the significance of this discovery is enhanced by the light it sheds upon and the confirmation it brings to the famous neanderthal skull and others of similar character, which for a long time had been subjects of vigorous discussion. before describing it, therefore, we will give a brief account of the previous discoveries. [footnote df: see pp. , .] the famous neanderthal skull was brought to light in by workmen in a limestone-quarry, near düsseldorf, in the valley of the neander, a small tributary to the rhine. by these workmen a cavern was opened upon the southern side of the winding ravine, about sixty feet above the stream and one hundred feet below the top of the cliff. the skull attracted much attention from its supposed possession of many apelike characteristics; indeed, it was represented by some to be a real intermediate link between man and the anthropoid apes. the accompanying cut enables one to compare the outline of the neanderthal skull with that of a chimpanzee on the one hand and of the highly developed european on the other. the apelike peculiarities of this skull appear in its vertical depression, in the enormous thickness of the bony ridges just above the eyes, and in the gradual slope of the back part of the head, together with some other characteristics which can only be described in technical language; so that it was pronounced by the highest authorities the most apelike of human crania which had yet been discovered. unfortunately, the jaw was not found. the capacity of the skull, however, was seventy-five cubic inches, which is far above that of the highest of the apes, being indeed equal to the average capacity of polynesian and hottentot skulls.[dg] huxley well remarks that "so large a mass of brain as this would alone suggest that the pithecoid tendencies indicated by this skull did not extend deep into the organization." [footnote dg: huxley's man's place in nature, p. .] [illustration: fig. .--comparison of forms of skulls: _a_, european; _b_, the neanderthal man; c, a chimpanzee (after lyell).] [illustration: fig. .--skull of the man of spy. (from photograph.)] upon extending inquiries, it was found that the neanderthal type of skull is one which still has representatives in all nations; so that it is unsafe to infer that the individual was a representative of all the individuals living in his time. the skull of bruce, the celebrated scotch hero, was a close reproduction of the neanderthal type; while, according to quatrefages,[dh] the skull of the bishop of toul in the fourth century "even exaggerates some of the most striking features of the neanderthal cranium. the forehead is still more receding, the vault more depressed, and the head so long that the cephalic index is - ." the discovery of messrs. fraipont and lohest adds much to our definite knowledge of the neanderthal type of man, since the belgic specimens are far more complete than any others heretofore found, there being in their collection two skulls, together with the jawbones and most of the other parts of the frame. in this case also there is no suspicion that the deposits had been disturbed, so as to admit any intrusion of human relics into the company of relics of an earlier age. according to m, lohest, there were three distinct ossiferous beds, separated by layers of stalagmite. all the ossiferous beds contained the remains of the mammoth, but in the upper stratum they were few, and probably intrusive. the implements found in this were also of a more modern type. in the second stratum from the top numerous hearths were found with burnt wood and ashes, together with the bones of the rhinoceros, the horse, the mammoth, the cave-bear, and the cave-hyena, all of which were abundant, while there were also specimens of the irish elk, the reindeer, the bison, the cave-lion, and several other species. in this layer also there were numerous implements of ivory, together with ornaments and some faint indications of carving upon the rib of a mammoth, besides a few fragments of pottery. [footnote dh: human species, p. ,] it was in the third, or lowest, of these beds that the skeletons were found. here they were associated with abundant remains of the rhinoceros, the horse, the bison, the mastodon, the cave-hyena, and a few other extinct species. flint implements also, of the "mousterien" pattern (which, according to the opinion of the french archæologists, is characteristic of middle palæolithic times), were abundant neither of the skeletons was complete, but they were sufficiently so to give an adequate idea of the type to which they belong, and one of the skulls is nearly perfect. according to m. fraipont, "one of these skulls is apparently that of an old woman, the other that of a middle-aged man. they are both very thick; the former is clearly dolichocephalic (long-headed, index ), the other less so. both have very prominent eyebrows and large orbits, with low, retreating foreheads, excessively so in the woman. the lower jaws are heavy. the older has almost no projecting chin. the teeth are large, and the last molar is as large as the others. these points are characteristic of an inferior and the oldest-known race. the bones indicate, like those of the neanderthal and naulette specimens, small, square-shouldered individuals." they were "powerfully built, with strong, curiously curved thigh-bones, the lower ends of which are so fashioned that they must have walked with a bend at the knees."[di] [footnote di: huxley, nineteenth century, vol. xxviii (november, ), p. .] other crania from various quaternary deposits in europe seem to warrant the inference that this type of man was the prevalent one during the early part of the palæolithic age. as long ago as a skull of this type was exhumed in canstadt, a village in the neighbourhood of stuttgart, in würtemberg. this was found in coexistence with the extinct animals whose bones we have described as so often appearing in the high-level river-gravel of the glacial age. but the importance of the discovery at canstadt was not appreciated until about the middle of the present century. from the priority of the discovery, and of the discussion among german anthropologists concerning it, it has been thought proper, however, by some to give the name of this village to the race and call it the "canstadt race." but, whatever name prevails, it is important in our reading to keep in mind that the man of canstadt, the man of neanderthal, and the man of spy are identical in type, and probably in age. similar discoveries have been made in various other places. among these are a lower jaw of the same type discovered in by m. dupont, at naulette, in the valley of the lesse, in belgium, and associated with the remains of extinct animals; a jawbone found in a grotto at arcy; a fragment of a skull found in by faudel, in the loess of eguisheim, near colmar; a skull at olmo, discovered in , in a compact clayey deposit forty-five feet below the surface; and a skull discovered in at marcilly. m. dupont has brought to light much additional testimony to glacial man from other caves in different parts of belgium. in all he has explored as many as sixty. three of these, in the valley of the montaigle, situated about one hundred feet above the river, contained both remains of man and many bones of the mammoth and other associated animals, which had evidently been brought in for food. in the hilly parts of germany, also, and in hungary, and even in the ural mountains in russia, and in one of the provinces of siberia, the remains of the rhinoceros, and most of the other animals associated with man in glacial times, have been found in the cave deposits which have been examined. though it can not be directly proved that these animals were associated with man in any of these places, still it is interesting to see how wide-spread the animals were in northern europe and asia during the glacial period. some northern animals, also, spread at this time into southern europe--remains of the reindeer having been discovered on the south slope of the pyrenees, but the remains of the mammoth, the woolly rhinoceros, and the musk ox, have not been found so far south. african species of the elephant, however, seem at one time to have had free range throughout spain, and the hippopotamus roamed in vast herds over the valleys of sicily, while several species of pygmy elephants seem to be peculiar to the island of malta. in the case of all the cave deposits referred to (with possibly the exception of those of victoria, england, and cae gwyn, wales), the evidence of man's existence during the glacial period is inferential, and consists largely in the fact that he was associated with various extinct animals which did not long survive that period, or with animals that have since retired from europe to their natural habitat in mountain-heights or high latitudes. the men whose remains are found in the high-level river-drift, and in the caverns described, were evidently not in possession of domestic animals, as their bones are conspicuous for their absence in all these places. the horse, which would seem to be an exception, was doubtless used for food, and not for service. if we were writing upon the general subject of the antiquity and development of the human race, we should speak here in detail of several other caves and rock shelters in france and southern europe, where remains of man belonging to an earlier period have been found. we should mention the rock shelter of cro-magnon in the valley of vezère, as well as that of mentone, where entire human skeletons were found. but it is doubtful if these and other remains from caves which might be mentioned belong in any proper sense to the glacial period. the same remarks should be made also with reference to the lake-dwellings in switzerland, of which so much has been written in late years. all these belong to a much later age than the river-drift man of whom we are speaking, and of whom we have such abundant evidence both in europe and in america. [illustration: fig. .--tooth of machairodus neogæus, × / (drawn from a cast).] [illustration: fig. .--perfect tooth of an elephas, found in stanislaus county, california, / natural size.] _extinct animals associated with man during the glacial period._ this is the proper place in which to speak more fully of the extinct animals which accompanied man in his earliest occupation of europe and america, and whose remains are so abundant in the river-drift gravel and in the caves of england, in connection with the relics of man. among these animals are the lion, which is now confined, to africa and the warmer portions of asia. but in glacial times a large species of this genus ranged over europe from sicily to central england. the saber-toothed tiger, with tusks ten inches long: (machairodus latidens), is now extinct. this species was in existence during the latter part of the tertiary period, but continued on until after man's appearance in the glacial period. the presence of this animal would seem to indicate a warm climate. the leopard (_felis pardus_) is now confined to africa and southern asia, and the larger islands adjoining; but during man's occupation of europe in the glacial epoch he was evidently haunted at every step by this animal; for his bones are found as far north in england as palæolithic man is known to have ranged. the hyena. two species of this animal are found in the bone-caves of europe. during the glacial epoch they ranged as far up as northern england, but they are now limited to africa and southwestern asia. [illustration: fig. .--skull of _hyena spelæa_, × / .] the elephant is represented in the preglacial and glacial epochs by several species, some of which ranged as far north as siberia. the african elephant is not now found north of the pyrenees and the alps. but a species of dwarf elephant, but four or five feet in height, has already been referred to as having occupied malta and sicily; and still another species has been found in malta, whose average height was less than three feet. an extinct species (elephas antiquus), whose remains are found in the river-drift and in the lower strata of sediment in many caverns as far north as yorkshire, england, was of unusual size, and during the glacial period was found on both sides of the mediterranean. but the species most frequently met with in palæolithic times was the mammoth (_elephas primigenius_). this animal, now extinct, accompanied man in nearly every portion both of europe and north america, and lingered far down into post-glacial times before becoming extinct. this animal was nearly twice the weight of the modern elephant, and one third taller. occasionally his tusks were more than twelve feet long, and curved upward in a circle. it is the carcasses of this animal which have been found in the frozen soil of siberia and alaska. it had a thick covering of long, black hair, with a dense matting of reddish wool at the roots. during the glacial period these animals must have roamed in vast herds over the plains of northern france and southern england, and the northern half of north america. [illustration: fig. .--celebrated skeleton of mammoth, in st. petersburg museum.] [illustration: fig. .--molar tooth of mammoth (_elephas primigenius_): _a_, grinding surface; _b_, side view.] the hippopotamus is at present a familiar animal in the larger rivers of africa, but is not now found in europe. during the glacial period, however, he ranged as far north as yorkshire, england, and his remains were found in close association with those of man, both in europe and on the pacific coast in america. twenty tons of their bones have been taken from a single cave in sicily.[dj] [footnote dj: prestwich's geology, vol. ii, p. .] [illustration: fig. .--tooth of _mastodon americanus_.] the mammoth and the rhinoceros we know to have been adapted to cold climates by the possession of long hair and thick fur, but the hippopotamus by its love for water would seem to be precluded from the possession of this protective covering. it is suggested, however, by sir william dawson, that he may have been adapted to arctic climates by a fatty covering, as the walrus is at the present time. a difficulty in accounting for many of the remains of the hippopotamus in some of the english caverns is that they are so far away from present or possible water-courses. but it would seem that due credit has not been ordinarily given to the migratory instincts of the animal. in southern africa they are known to "travel speedily for miles over land from one pool of a dried-up river to another; but it is by water that their powers of locomotion are surpassingly great, not only in rivers, but in the sea.... the geologist, therefore, may freely speculate on the time when herds of hippopotami issued from north african rivers, such as the nile, and swam northward in summer along the coasts of the mediterranean, or even occasionally visited islands near the shore. here and there they may have landed to graze or browse, tarrying awhile, and afterwards continuing their course northward. others may have swum in a few summer days from rivers in the south of spain or france to the somme, thames, or severn, making timely retreat to the south before the snow and ice set in."[dk] [footnote dk: lyell, antiquity of man, p. ,] the mastodon (_mastodon americanus_), (fig. ), "is probably the largest land mammal known, unless we except the dinotherium. it was twelve to thirteen feet high, and, including the tusks, twenty-four to twenty-five feet long. it differed from the elephant chiefly in the character of its teeth. the difference is seen in figs. and . the elephant's tooth given above (fig. ) is sixteen inches long, and the grinding surface eight inches by four." [illustration: fig. .--_mastodon americanus_ (after owen).] the mastodon, together with the mammoth, made their appearance about the middle of the miocene epoch. at the close of the tertiary period the mastodon became extinct on the eastern continent, but continued in north america to be a companion of man well on toward the close of the glacial period. many perfect skeletons have been found in the deposits of this period in north america. "one magnificent specimen was found in a marsh near newburg, new york, with its legs bent under the body, and the head thrown up, evidently in the very position in which it mired. the teeth were still filled with the half-chewed remnants of its food, which consisted of twigs of spruce, fir, and other trees; and within the ribs, in the place where the stomach had been, a large quantity of similar material was found."[dl] [footnote dl: le conte's geology (edition of ), p. .] the rhinoceros is now confined to africa and southern asia; but the remains of four species have been found in america, europe, and northern asia, in deposits of the glacial period. in company with that of the mammoth, already spoken of, a carcass of the woolly rhinoceros was found in in the frozen soil of northern siberia. the bones of other species have been found as far north as yorkshire, england. in the valley of the somme there was found "the whole hind limb of a rhinoceros, the bones of which were still in their true relative position. they must have been joined together by ligaments and even surrounded by muscles at the time of their interment." an entire skeleton was found near by. the gravel terrace in which these occurred is about forty feet above the floor of the valley, and must have been formed subsequent to some of the strata which contained the remains of human art. in america the bones are found in the gold-bearing gravels of california, in connection with human remains. [illustration: fig. .--skeleton of _rhinoceros tichorhinus_.] [illustration: fig. .--skull of cave-bear (_ursus spelæus_),] the bear was represented in europe in palæolithic times by three species, of which only one exists there at the present time. but during the glacial period the grizzly bear, now confined to the western part of america, and the extinct cave-bear were companions, or enemies as the case may be, of man throughout europe. the cave-bear was of large size, and his bones occur almost everywhere in the lower strata of sediment in the caves of england. the great irish elk, or deer, is now extinct, though it is supposed by some to have lingered until historic times. its remains are found widely distributed over middle europe in deposits of palæolithic age. [illustration: fig. .--skeleton of the irish elk (_cervus megaceros_).] the horse was also, as we have seen, a very constant associate of man in middle europe during the palæolithic age, but probably not as a domesticated animal. the evidence is pretty conclusive that he was prized chiefly for food. about some of the caves in france such immense quantities of their bones are found that they can be accounted for best as refuse-heaps into which the useless bones had been thrown after their feasts, after the manner of the disposal of shells of shell-fish. in america the horses associated with man were probably of a species now extinct. the skull of one (_equus excelsus_) recently found in texas, in pleistocene deposits, associated with human implements, is, according to cope, intermediate in character between the horse and quagga.[dm] the frontal bone was crushed in in a manner to suggest that it had been knocked in the head with a stone hammer, such as was found in the same bed. possibly, therefore, man's love of horse-flesh may have been an important element in securing the extinction of the species in america. [footnote dm: american naturalist, vol. xxv (october, ), p. .] besides these animals there were associated with man at this time the musk sheep and the reindeer, both now confined to the regions of the far north, but during the glacial period ranging into southern france, and mingling their bones with those both of man and of the southern species already enumerated. [illustration: fig. .--musk-sheep (_ovibos moschatius_).] the wolverine, the arctic fox, the marmot, the lemming--all now confined to colder regions--at that time mingled on the plains of central europe with the species mentioned as belonging now to africa and southern asia. the ibex, also, and the snowy vole and chamois descended to the plains from their mountain-heights, and joined in the strange companionship of animals from the north and from the south. besides these extremes there were associated with man during the glacial period numerous representatives of the temperate group of existing animals, such as the bison, the horse, the stag, the beaver, the hare, the rabbit, the otter, the weasel, the wild-cat, the fox, the wolf, the wild boar, and the brown bear. [illustration: fig. .--reindeer.] to account for this strange intermingling of arctic and torrid species of animals, especially in europe, during man's occupancy of the region in glacial times, various theories have been resorted to, but none of them can be said to be altogether satisfactory. one hypothesis is that the bones of these diverse animals became mingled by reason of the great range of the annual migration of the species. the reindeer, for example, still performs extensive annual migrations. in summer it ventures far out upon the _tundras_ of north america and siberia to feed upon the abundant vegetation that springs up like magic under the influence of the long days of sunshine; while, as winter approaches, it returns to the forests of the interior. or in other places this animal and his associates, like birds of passage, move northward in summer to escape the heat, and southward in the winter to escape the extreme cold. many of the other animals also are more or less migratory in their habits. thus it is thought that during the glacial period, when man occupied northern france and southern england, the reindeer, the musk sheep, the arctic fox, and perhaps the hippopotamus and some other animals, annually vibrated between northern england and southern france, a slight elevation of the region furnishing a land passage from england to the continent; while the chamois and other alpine species vibrated as regularly between the valleys in winter and the mountain-heights in summer. the habits of these species are such that it is not difficult to see how in their case this migration could have taken place. professor boyd dawkins attempts to reduce the difficulty by supposing that the glacial epoch was marked by the occurrence of minor periods of climatic variation, during which, in comparatively short periods, the isothermal lines vibrated from north to south, and _vice versa_. in this view the southern species gradually crowded upon the northern during the periods of climatic amelioration, until they reached their limit in central england, and then in turn, as the climate became more rigorous, slowly retreated before the pressure of their northern competitors. meanwhile the hyena sallied forth from his various caves, over this region, at one time of the year to feed upon the reindeer, and at another time of the year upon the flesh of the hippopotamus, in both cases dragging their bones with him to his sheltered retreat in the limestone caverns[dn] which he shared at intervals with palæolithic man. [footnote dn: early man in britain, p. .] the theory of mr. james geikie is that the period, while one of great precipitation, was characterised by a climate of comparatively even temperature, in which there was not so great a difference as now between the winters and the summers, the winters not being so cold and the summers not so hot as at present. this is substantially the condition of things in southern alaska at the present time, where extensive glaciers come down to the sea-level, even though the thermometer at sitka rarely goes below zero (fahrenheit). it is, therefore, easy to conceive that if there were extensive plains bordering the alaskan archipelago, so as to furnish ranging grounds for more southern species, the animals of the north and the animals of the south might partially occupy the same belt of territory, and their bones become mingled in the same river deposits. in order to clear the way for either of these hypotheses to account for the mingling of arctic and torrid species characteristic of the period under consideration in europe, we must probably suppose such an elevation of the region to the south as to afford land connection between europe and africa. this would be furnished by only a moderate amount of elevation across the strait of gibraltar and from the south of italy to the opposite shore in africa; and there are many indications, in the distribution of species, of the existence in late geological times of such connection. it should also be observed that the present capacities and habits of species are not a certain criterion of their past habits and capacities. as already remarked, both the rhinoceros and the mammoth of glacial times were probably furnished with a woolly protection, which enabled them to endure more cold than their present descendants could do, while the elephant is even now known to be able to endure the rigors of the climate at great elevations upon the himalaya mountains. we can easily imagine these species to have been adjusted to quite different climatic conditions from those which now seem necessary to their existence. in the case of the hippopotamus, also, it is quite possible, as already suggested, that it is more inclined to migration than is generally supposed. geikie's theory of the prevalence of an equable climate during a portion of the glacial period in europe is thought to be further sustained by the character of the vegetation which then covered the region, as well as by the remains of the mollusks which occupied the waters. then "temperate and southern species like the ash, the poplar, the sycamore, the fig-tree, the judas-tree, the laurel, etc., overspread all the low ground of france, as far north at least as paris.... it was under such conditions," continues geikie, "that the elephants, rhinoceroses, and hippopotamuses, and the vast herds of temperate cervine and bovine species ranged over europe, from the shores of the mediterranean up to the latitude of yorkshire, and probably even farther north still; and from the borders of asia to the western ocean. despite the presence of numerous fierce carnivora--lions, hyenas, tigers, and others--europe at that time, with its shady forests, its laurel-margined streams, its broad and deep-flowing rivers, a country in every way suited to the needs of a race of hunters and fishers--must have been no unpleasant habitation for palæolithic man. "this, however, is only one side of the picture. there was a time when the climate of pleistocene europe presented the strongest contrast to those genial conditions--a time when the dwarf birch of the scottish highlands, and the arctic willow, with their northern congeners, grew upon the low grounds of middle europe. arctic animals, such as the musk sheep and the reindeer, lived then, all the year round, in the south of france; the mammoth ranged into spain and italy; the glutton descended to the shores of the mediterranean; the marmot came down to the low grounds at the foot of the apennines; and the lagomys inhabited the low-lying maritime districts of corsica and sardinia. the land and fresh-water shells of many pleistocene deposits tell a similar tale; boreal, high alpine, and hyperborean forms are characteristic of these accumulations in central europe; even in the southern regions of our continent the shells testify to a former colder and wetter climate."[do] [footnote do: prehistoric europe, p. .] in mr. geikie's view these facts indicate two glacial periods, with an intervening epoch of mild climate. in the opinion of others they are readily explainable by the coming on and departure of a single ice age, with its various minor episodes. _earliest remains of man on the pacific coast of north america._ most interesting evidence concerning the antiquity of man in america, and his relation to the glacial period, has come from the pacific coast. during the height of the mining activity in california, from to , numerous reports were rife that human remains had been discovered in the gold-bearing gravel upon the flanks of the sierra nevada mountains. these reports did not attract much scientific attention until they came to relate to the gravel deposits found deeply buried beneath a flow of lava locally known as the sonora or tuolumne table mountain. this lava issued from a vent near the summit of the mountain-range, and flowed down the valley of the stanislaus river for a distance of fifty or sixty miles, burying everything in the valley beneath it, and compelling the river to seek another channel. the thickness of the lava averages about one hundred feet, and so long a time has elapsed since the eruption that the softer strata on either side of the valley down which it flowed have been worn away to such an extent that the lava now rises nearly everywhere above the general level, and has become a striking feature in the landscape, stretching for many miles as a flat-topped ridge about half a mile in width, and presenting upon the sides a perpendicular face of solid basalt for a considerable distance near the lower end of the flow. [illustration: fig. .--section across table mountain, tuolumne county, california: _l_, lava; _g_, gravel; _s_, slate; _r_, old river-bed; _r'_, present river-bed.] [illustration: fig. .--calaveras skull. (from whitney.)] it was under this mountain of lava that the numerous implements and remains of man occurred which were reported to professor j. d. whitney when he was conducting the geological survey of california between and . the implements consisted of stone mortars and pestles, suitable for use in grinding acorns and other coarse articles of food. there were, however, some rude articles of ornament. in one of the mining shafts penetrating the gravel underneath table mountain, near sonora, there was reported to have been discovered, in , a human jawbone, one portion of which was sent by responsible parties to the boston society of natural history, and another part to the philadelphia academy of sciences, in whose collections the fragments can now be seen. interest reached a still higher pitch when, in , an entire human skull with some other human bones was reported to have been discovered under this same lava deposit, a few miles from sonora, at altaville, in calaveras county, and hence known as the "calaveras skull." persistent efforts were made soon after to discredit the genuineness of this discovery. bret harte showered upon it the shafts of his ridicule, and various other persons gave currency to the story that the whole report originated in a joke played by the miners upon unsuspecting geologists. these attacks were so successful that many conservative archæologists and men of science have refused to accept the skull as genuine. recent events, however, have brought such additional evidence[dp] to the support of this discovery that it would seem unreasonable any longer to refuse to credit the testimony. at the meeting of the geological society of america, at washington, in january, , mr. george p. becker, of the united states geological survey, who for some years has had charge of investigations relating to the gold-bearing gravels of the pacific coast, presented the affidavit of mr. j. h. neale, a well-known mining engineer of unquestionable character, stating that he had taken a stone mortar and pestle, together with some spear-heads (which through mr. becker he presented to the society), from undisturbed strata of gravel underneath the lava of table mountain, near rawhide gulch, a few miles from sonora. at the same meeting mr. becker presented a pestle which mr. clarence king, the first director of the united states geological survey, took with his own hands out of undisturbed gravel under this same lava deposit, near tuttletown, a mile or two from the preceding locality mentioned. [footnote dp: see bulletin geological society of america, , pp. - .] i was so fortunate, also, as to be able to report to the society at the same meeting the discovery, in , of a small stone mortar by mr. c. mctarnahan, the assistant surveyor of tuolumne county. this mortar was found by mr. mctarnahan in the empire mine, which penetrates the gravel underneath table mountain, about three miles from sonora, and not far from the other localities above mentioned. the place where the mortar was found is about one hundred and seventy-five feet in from the edge of the superincumbent lava, which is here about one hundred feet in thickness. at my request, this mortar was presented by its owner, mrs. m. j. darwin, to the western reserve historical society of cleveland, ohio, in whose collection it can now be seen. these three independent instances, each of them authenticated by the best of evidence, have such cumulative force that probably few men of science will longer stand out against it. associated with these discoveries, there is to be mentioned another, which was brought to my notice by mr. charles francis adams in october, .[dq] this was a miniature clay image of a female form, about one inch and a half in length, and beautifully formed, which was found, in august, , by mr. m. a. kurtz, while boring an artesian well at nampa, ada county, idaho. the strata passed through included, near the surface, fifteen feet of lava. underneath this, alternating beds of clay and quicksand occurred to a depth of three hundred and twenty feet, where there appeared indications of a former surface soil lying just above the bed-rock, from which the clay image was brought up in the sand-pump. [footnote dq: see proceedings boston society natural history, january, , and february, .] [illustration: fig. .--three views of nampa image drawn to scale. the middle one is from a photograph.] i devoted the summer of to a careful study of the lava deposits both in idaho and in california, with a view to learning their significance with reference to these discoveries. the main facts brought to light by this investigation are that in the snake river valley, idaho, there are not far from twelve thousand square miles of territory covered with a continuous stratum of basaltic lava, extending nearly across the entire diameter of the state from east to west. nampa, where the miniature image was discovered, is within five miles of the western limit of this lava-flow, and where it had greatly thinned out. the relative age of the lava is shown by its relation to tertiary beds of shale and sandstone, containing numerous fossils of late pliocene species. these are overlaid in this vicinity by the lava, thus determining its post-tertiary character. examination with reference to the more precise determination of age reveals channels of erosion formed since the lava-flow took place, which, when studied sufficiently, will probably lead to valuable approximate results. at present i can only say that the amount of erosion since the lava eruptions of western idaho is not excessive, and very likely may be brought within a period of from ten thousand to twenty thousand years. the enormous erosion in the cañon of the snake river, near shoshone falls, in central idaho, is doubtless of a much earlier date than that in the boise river, near nampa. [illustration: fig. .--map showing pocatello, nampa, and the valley of snake river.] the disturbances created in this part of the valley by the bursting of the barriers between the glacial lake bonneville and the snake river, already described (see above, page ), have not been worked out. there can be no doubt, however, that interesting results will come to light in connection with the problem; for pocatello, the point at which the _débâcle_ reached the snake river plain, is about , feet higher than nampa, and miles distant, and the water must have poured into the valley faster than the river in its upper portion could have discharged it. by just what channels the mighty current worked down to the lower levels on the western borders of the state it would be most interesting as well as instructive to know. a study of the situation in tuolumne and calaveras counties, california, reveals a state of things closely resembling, in important respects, that in western idaho. at first sight the impression is made that an immense lapse of time must have occurred since the volcanic eruption which furnished the lava of table mountain. the stanislaus river flows in a channel of erosion a thousand feet or more lower than the ancient channel filled by lava, and in two or three places cuts directly across it. an immense amount of time, also, would seem to be required to permit the smaller local streams to have worn away so much of the sides of the ancient valley as to allow the lava deposit now so continuously to rise above the general surface. still, the question of absolute time cannot be considered separately without much further study. it is by no means certain that, when the lava-stream poured down the mountain, it always followed the lowest depressions; but at certain points it may have been dammed up in its course by its own accumulations so as to be turned off into what was then an ancient abandoned channel. [illustration: fig. .--section along the line, north and south: _r' r'_, old river-beds; _r r_, present river-beds; _l_, lava; _sl_, slate.] the forms of animal and vegetable life with which the remains of man under table mountain are associated, are, indeed, to a considerable extent, species now extinct in california, and some of them no longer exist anywhere in the world. but a suggestion of professor prestwich, in england, made with reference to the extinct forms of life associated with human remains in the glacial deposits in europe, is revived by mr. becker, of the geological survey, with reference to the california discoveries; his inference being, not that man is so extremely ancient in california, but that many of these plants and animals have continued to a more recent date than has ordinarily been supposed. the connection of these lava-flows on the pacific coast with the glacial period is unquestionably close. for some reason which we do not fully understand, the vast accumulation of ice in north america during the glacial period is correlated with enormous eruptions of lava west of the rocky mountains, and, in connection with these events, there took place on the pacific coast an almost entire change in the plants and animals occupying the region. mr. warren upham is of the opinion that on the pacific coast they lingered much later than in the region east of the rocky mountains. indeed, it is pretty certain that not many centuries have elapsed since the glacial phenomena of the sierra nevada mountains were much more pronounced than they are at the present time, and it is equally certain that there have been vast eruptions of lava in california within three hundred years. from these data, therefore, mr. becker has real foundation for his suggestion that perhaps in the glacial period california was a kind of health resort for pliocene animals, as it is at the present time for man; or, at any rate, that the later date of the accumulations permitted the animals to survive there much longer than in the region east of the rocky mountains. further discussion of the preceding facts will profitably be deferred until, in the next two chapters, the questions of the cause and date of the glacial period have been considered. chapter ix. the cause of the glacial period. in searching for the cause of the glacial period, it is evident that we must endeavor to find conditions which will secure over the centre of the glaciated area either a great increase of snow-fall or a great decrease in the mean annual temperature, or both of these conditions combined in greater or less degree. as can be seen, both from the nature of the case and from the unglaciated condition of siberia and northern alaska, a low degree of temperature is not sufficient to produce permanent ice-fields. if the snow-fall is excessively meagre, even the small amount of heat in an arctic summer will be sufficient to melt it all away. from the condition of greenland, however, it appears that a moderate amount of precipitation where it is chiefly in the form of snow may produce enormous glaciers if at the same time the average temperature is low. in southeastern alaska, on the other hand, the glaciers are of enormous size, though the mean annual temperature is by no means low, for there the great amount of snow-fall amply compensates for the higher temperature. snow stores the cold and keeps it in a definite place. if the air becomes chilled, circulation at once sets in, and the cold air is transferred to warmer regions; but if there is moisture in the air, so that snow forms, the cold becomes locked up, as it were, and falls to the earth. the amount of cold thus locked up in snow is enormous. to melt one cubic foot of ice requires as much heat as would raise the temperature of a cubic foot of water ° fahrenheit. to melt a "layer of ice only one inch and a half thick would require as much heat as would raise a stratum of air eight hundred feet thick from the freezing-point to the tropical heat of ° fahrenheit." it is the slowness with which ice melts which enables it to accumulate as it does, both in winter and upon high mountains and in arctic regions. captain scoresby relates that when near the north pole the sun would sometimes be so hot as to melt the pitch on the south side of his vessel, while water was freezing on the north side, in the shade, owing to the cooling effect of the masses of ice with which he was surrounded. thus it will appear that a change in the direction of the moist winds blowing from the equator towards the poles might produce a glacial epoch. if snow falls upon the ocean it cools the water, but through the currents, everywhere visible in the sea, the temperature in the water in the different parts soon becomes equalized. if, however, the snow falls upon the land, it must be melted by the direct action of the sun and wind upon the spot where it is. if the heat furnished by these agencies is not sufficient to do it year by year, there will soon be such an accumulation that glaciers will begin to form. it is clear, therefore, that the conditions producing a glacial period are likely to prove very complicated, and we need not be surprised if the conclusions to which we come are incapable of demonstration. theories respecting the cause of the glacial period may be roughly classified as astronomical and geological. among the astronomical theories, one which has sometimes been adduced is that the solar system in its movement through space is subjected to different degrees of heat at different times. according to this theory, the temperate climate which characterised the polar regions during the tertiary period, and continued up to the beginning of the glacial epoch, was produced by the influence of the warmer stretches of space through which the whole solar system was moving at that time; while the glacial period resulted from the influence upon the earth of the colder spaces through which the system subsequently moved. while it is impossible absolutely to disprove this hypothesis, it labors under the difficulty of having little positive evidence in its favor, and thus contravenes a fundamental law of scientific reasoning, that we must have a real cause upon which to rest our theories. in endeavouring to explain the unknown, we should have something known to start with. but in this case we are not sure that there are any such variations in the temperature of the space through which the solar system moves. this theory, therefore, cannot come in for serious consideration until all others have been absolutely disproved. as we shall also more fully see, in the subsequent discussion, the distribution of the ice during the glacial period was not such as to indicate a gradual extension of it from the north pole, but rather the accumulation upon centres many degrees to the south. closely allied with the preceding theory is the supposition broached by some astronomers that the sun is a variable star, dependent to some extent for its heat upon the impact of meteorites, or to the varying rapidity with which the contraction of its volume is proceeding. it is well known that when two solid bodies clash together, heat is produced proportionate to the momentum of the two bodies. in other words, the motion which is arrested is transformed into heat. mr. croll, in his last publication[dr] upon the subject, ingeniously attempted to account for the gaseous condition of the nebulæ and the heat of the sun and other fixed stars by supposing it to be simply transformed motion. according to this theory, the original form of force imparted to the universe was that exerted in setting in motion innumerable dark bodies, which from time to time have collided with each other. the effects of such collisions would be to transform a large amount of motion into heat and its accompanying forms of molecular force. the violence of the compact of two worlds would be so great as to break them up into the original atoms of which they are composed, and the heat set free would be sufficient to keep the masses in a gaseous condition and cause them to swell out into enormous proportions. from that time on, as the heat radiated into space, there would be the gradual contraction which we suppose is going on in all the central suns, accompanied, of course, with a gradual decline of the heat-energy in the system. [footnote dr: stellar evolution and its relation to geological time.] now, it is well known that the earth and the solar system in their onward progress pass through trains of meteorites. the tails of some of the comets are indeed pretty clearly proved to be streams of ponderable matter, through which, from time to time, the minor members of the solar system plunge, and receive some accession to their bulk and weight. the shooting-stars, which occasionally attract our attention in the sky, mark the course of such meteorites as they pass through the earth's atmosphere, and are heated to a glow by the friction with it. it has been suggested, therefore, that the sun itself may at times have its amount of heat sensibly affected by such showers of meteorites or asteroids. upon this theory the warm period of the tertiary epoch, for instance, may have been due to the heat temporarily added to the sun by impact with minor astronomical bodies. when, afterwards, it gradually cooled down, receiving through a long period no more accessions of heat from that source, the way was prepared for the colder epoch of the glacial period, which, in turn, was dispelled by fresh showers of meteorites upon the sun, sufficient to produce the amelioration of climate which we experience at the present time. as intimated, this theory is closely allied to the preceding, the principal difference being that it limits the effects of the supposed cause to the solar system, and looks to our sun as the varying source of heat-supply. it has the advantage over that, however, of possessing a more tangible _vera causa_. meteorites, asteroids, and comets are known to be within this system, and have occasional collisions with other members of it. but the principal objection urged against the preceding theory applies here, also, with equal force. the accumulations of ice during the glacial period were not determined by latitude. in north america the centre of accumulation was south of the arctic circle--a fact which points clearly enough to some other cause than that of a general lowering of the temperature exterior to the earth. the same objections would bear against the theory ably set forth by mr. sereno e. bishop, of honolulu, which, in substance, is that there may be considerable variability in the sun's emission of heat, owing to fluctuations in the rate of the shrinkage of its diameter, brought about by the unequal struggle between the diminishing amount of heat in the interior and the increasing force of the gravitation of its particles, and by the changes in the enveloping atmosphere of the sun, which, like an enswathing blanket, arrests a large portion of the radiant heat from the nucleus, and is itself evidently subject to violent movements, some of which seem to carry it down to the sun's interior. unknown electrical forces, he thinks, may also combine to add an element of variability. these supposed changes may be compared to those which take place upon the surface of the earth when, at irregular intervals, immense sheets of lava, like those upon the pacific coast of north america, are exuded in a comparatively brief time, to be succeeded by a long period of rest. the heat thus brought to the surface of the earth would add perceptibly to that radiated from it into space in ordinary times. something similar to this upon the sun, it is thought, might produce effects perceptible upon the earth, and account for alternate periods of heat and cold. a fourth astronomical theory is that there has been a shifting of the earth's axis; that at the time of the glacial period the north pole, instead of being where it now is, was somewhere in the region of central greenland. this attractive theory has been thought worthy of attention by president t. c. chamberlin and by professor g. c. comstock,[ds] but it likewise labours under a twofold difficulty: first, the shifting of the poles observed ( feet per year) is too slight to have produced the changes within any reasonable time, and it is not likely to have been continuous for a long period. but still more fatal to the theory is the fact that the warm climate preceding the glacial period seems to have extended towards the present north pole upon every side; a temperate flora having been found in the fossil plants of the tertiary beds in greenland and northern british america, as well as upon nova zembla and spitzbergen. [footnote ds: see papers by these gentlemen read at the meeting of the american association for the advancement of science, in washington, in august, . professor comstock's paper appeared in the american journal of science for january, .] a fifth astronomical theory, and one which has of late years been received with great favour, is that so ably advocated by the late dr. james croll and by professor james geikie. following the suggestions of the astronomer adhémar, these writers have attempted to show that not only one glacial epoch, but a succession of such epochs, has been produced in the world by the effect of the changes which are known to have taken place in the eccentricity of the earth's orbit when combined with the precession of the equinoxes--another calculable astronomical cause. [illustration: fig. .--diagram showing effect of precession: _a._ condition of things now; _b._ as it will be , years hence. the eccentricity is of course greatly exaggerated.] it is well known that the earth's orbit is elliptical; that is, it is longer in one direction than in the other, so that the sun is one side of the centre. during the winter of the northern hemisphere the earth is now about three million miles nearer the sun than in the summer; but the summer makes up for this distance by being about seven days longer than the winter. through the precession of the equinoxes this state of things will be reversed in ten thousand five hundred years; at which time we shall be nearer the sun during our northern summer, and farther away in winter, our winter then being also longer than our summer. besides, through the unequal attraction of the planets the eccentricity of the earth's orbit periodically increases and diminishes, so that there have been periods when the earth was ten million five hundred thousand miles farther from the sun in winter than in summer; at which times, also, the winter was nearly twenty-eight days longer than the summer. such an extreme elongation of the earth's orbit occurred about two hundred and fifty thousand years ago. it is easy to assume that such a change in astronomical conditions would produce great effects upon the earth's climate; and equally easy to connect with those effects the vast extension of ice during the glacial period. since, also, this period of extreme eccentricity terminated only eighty thousand years ago, the close of the glacial period would, perhaps, upon mr. croll's theory, be comparatively a recent event; for if the secular summer of the earth's eccentricity lags relatively as far behind the secular movements as the annual summer does behind the vernal equinox, we should, as professor charles h. hitchcock suggests, have to place the complete breaking up of the ice period as late as forty thousand years ago.[dt] [footnote dt: geology of new hampshire, vol. iii, p. .] we have no space to indicate, as it deserves, the comparative merits and demerits of this ingenious theory. it would, however, be a great calamity to have geologists accept it without scrutiny. it is, indeed, a part of the business of geologists to doubt such theories until they are verified by a thorough examination of all accessible _terrestrial_ evidence bearing upon the subject. there is no reason to question the reality of the variations in the relative positions of the earth and the sun assumed by mr. croll; though there may be serious doubt whether the effects of those changes upon climate would be all that is surmised, since equal amounts of heat would fall upon the earth during summer, whether made longer or shorter by the cause referred to. during the short summers the earth is so much nearer the sun that it receives each season absolutely as much heat as it does during the longer summers, when it is so much farther away from the sun. thus the theory rests at last upon the question what would become of the heat reaching the earth in these differing conditions. it is plausibly urged by mr. croll that when a hemisphere of the earth is passing through a period of long winters the radiation of heat will be so excessive that the temperature would fall much below what it would during the shorter winters; and so ice and snow would accumulate far beyond the usual amount. it is also supposed that the effect of the summer's sun in melting the ice during the short summer would be diminished through natural increase of the amount of foggy and cloudy weather. adhémar's theory is supposed by sir robert ball, royal astronomer of ireland, to be considerably re-enforced by a discovery which he has made concerning the distribution of heat upon the earth during the seasons culminating in the summer and winter solstices. croll had assumed, on the authority of herschel, that a hemisphere of the earth during the longer winter in aphelion would receive the same actual amount of heat which would fall upon it during the shorter summer in perihelion; whereas, according to dr. ball's discovery, "of the total amount of heat received from the sun on a hemisphere of the earth in the course of a year, sixty-three per cent is received during the summer and thirty-seven per cent during the winter."[du] when, therefore, the summers occur in perihelion the heat is more intense than croll had supposed, and, at the same time, the winters occurring in aphelion are more deficient in heat than he had assumed. this discovery of dr. ball will not, however, materially affect the discussion of croll's theory upon its inherent merits, since it is simply an intensification of the causes invoked by him. we will therefore let it stand or fall in the light of the general considerations hereafter to be adduced. [footnote du: cause of an ice age, p. .] the aid of theoretical consequent changes in the volume of the gulf stream, and in the area of the trade-winds, has also to be invoked by mr. croll. the theory likewise receives supposed confirmation from facts alleged concerning the present climate of the southern hemisphere which is passing through the astronomical conditions thought to be favourable to its glaciation. the antarctic continent is completely enveloped in ice, even down to the sixty-seventh degree of latitude. a few degrees nearer the pole sir j. c. boss describes the ice as rising from the water in a precipitous wall one hundred and eighty feet high. in front of such a wall, and nearly twenty degrees from the south pole, this navigator sailed four hundred and fifty miles! voyagers, in general, are said to agree that the summers of the antarctic zone are much more foggy and cold than they are in corresponding latitudes in the northern hemisphere; and this, even though the sun is , , miles nearer the earth during the southern summer than it is during the northern. another direction from which evidence is invoked in confirmation of mr. croll's theory is the geological indications of successive glacial epochs in times past. if there be a recurring astronomical cause sufficient of itself to produce glacial periods, such periods should recur as often as the cause exists; but glaciation upon the scale of that which immediately preceded the historic era could hardly have occurred in early geological time without leaving marks which geologists would have discovered. were the "till" now covering the glaciated region to be converted into rock, its character would be unmistakable, and the deposit is so extensive that it could not escape notice. in his inaugural address before the british association in , professor ramsey, director-general of the geological survey of great britain, presented a formidable list of glacial observations in connection with rocks of a remote age.[dv] beginning at the earliest date, he cites professor archibald geikie, one of the most competent judges, as confident that the rounded knobs and knolls of laurentian rocks exposed over a large region in northwestern scotland, together with vast beds of coarse, angular, unstratified conglomerates, are unquestionable evidences of glacial action at that early period. masses of similar conglomerates, resembling consolidated glacial boulder-beds, occur also in the lower silurian formation at corswall, england. in dunbar, scotland, professor forbes also found, in formations of but little later age than the coal period, "brecciated conglomerates, consisting of pebbles and large blocks of stone, generally angular, embedded in a marly paste, in which some of the pebbles are as well scratched as those found in medial moraines." in formations of corresponding antiquity the geologists of india have found similar boulder-beds, in which some of the blocks are polished and striated. [footnote dv: nature (august , ), vol. xxii, pp. , .] still, this evidence is less abundant than we should expect, if there had been the repeated glacial epochs supposed by mr. croll's astronomical theory; and it is by no means impossible that the conglomerates of scratched stones described by professor ramsey in great britain, and by messrs. blandford and medlicott in india, may have resulted from local glaciers coming down from mountain-chains which have been since removed by erosion or subsidence. we are not aware that any incontestable evidence has been presented in america of any glaciation previous to that of _the_ glacial period. upon close consideration, also, it appears that mr. croll's theory has not properly taken into account the anomalous distribution of heat which we actually find to take place on the surface of the earth. he has done good service in showing what an enormous transfer of heat there is from the southern to the northern atlantic by means of the gulf stream, estimating that the heat conveyed by the gulf stream into the atlantic ocean is equal to one fifth of all possessed by the waters of the north atlantic; or to the heat received from the sun upon a million and a half square miles at the equator, or two million square miles in the temperate zone. "the stoppage of the gulf stream would deprive the atlantic of , , , , , , foot-pounds of energy in the form of heat per day." among the objections which bear against this ingenious theory is one which will appear with great force when we come to discuss the date of the glacial period, when we shall show that even professor hitchcock's supposition that the lingering effects of the last great eccentricity of the earth's orbit, continued down to forty thousand years ago, is not sufficient to account for the recentness of the close of the period as shown by abundant geological evidence. it is certainly not more than ten or fifteen thousand years ago that the ice finally melted off from the laurentian highlands; while on the pacific coast the period of glaciation was still more recent. from inspection of the accompanying map the main point of mr. croll's reasoning may be understood. it will be seen that the direction of the currents in the central atlantic is largely determined by the contour of the northeastern coast of south america. from some cause the southeast trade-winds are stronger than the northeast, and their force is felt in pushing the superficial currents of warm water farther north than cape st. roque, the eastern extremity of brazil. as the direction of the south american coast trends rapidly westward from this point to the isthmus of panama, the resultant of the forces is a strong current northwestward into the _cul-de-sac_ of the gulf of mexico, from which there is only the one outlet between cuba and the peninsula of florida. through this the warm water is forced into the region where westerly winds prevail, and spreads its genial influence far to the northward, modifying the climate of the british isles, and even of far-off norway. [illustration: fig. .--map showing course of currents in the atlantic ocean: _b_ and _b'_ are currents set in motion by opposite trade-winds; meeting, they produce the equatorial current, which divides into _c_ and _c'_, continuing on as _a_ and _a'_ and _e_.] but why are the southeast trade-winds of the atlantic stronger than the northeast? the ultimate reason, of course, is to be found in the fact that the northern hemisphere is warmer than the southern. the atmosphere over the northern-central portion of the atlantic region is more thoroughly rarefied by the sun's heat than is that over the region south of the equator. the strong southeast trades are simply the rush of atmosphere from the south atlantic to fill the vacuum caused by the heat of the sun north of the equator. but, again, why is this? because, says mr. croll, we are now in that stage of astronomical development favourable to the increased warmth of the northern hemisphere. in the northern hemisphere the summers are longer than the winters. perihelion occurs in winter and aphelion in summer. this is the reason why the north atlantic is warmer than the south atlantic, and why the trade-winds of the south are drawn to the north of the equator. ten thousand five hundred years ago, however, the conditions were reversed, and the greater rarefaction of the atmosphere would have taken place south of the equator, thus drawing the trade-winds in that direction. by again inspecting the map, one will see how far-reaching the effect on the climate of northern countries this change in the prevalences of the trades would have been. then, instead of having the northwest current leading along the northeast coast of south america into the gulf of mexico augmented by the warm currents circulating south of the equator, the warm currents of the north would have been pushed down so far that they would augment the current running to the southwest beyond cape st. roque, along the southeast shore of south america; thus the northern portion of the atlantic, instead of robbing the southern portion of heat, would itself be robbed of its warm currents to contribute to the superfluous heat of the south atlantic. this theory is certainly very ingenious. there is a weak point in it, however. mr. croll assumes that when the winters of the northern hemisphere occur in aphelion, they must necessarily be colder than now. but, evidently, this assertion implies a fuller knowledge than we possess of the laws by which the heat received from the sun is distributed over the earth. for it appears from observation that the equator is by no means so hot now as, theoretically, it ought to be, and that the arctic regions are not so cold as, according to theory, they should be, and this in places which could not be affected by oceanic currents. for example, at iquitos, on the amazon, only three hundred feet above tide, three degrees and a half south of the equator, and more than a thousand miles from the atlantic (so that ocean-currents cannot abstract the heat from its vicinity), the mean yearly temperature is but ° fahr.; while at verkhojansk, in northeast siberia, which is ° north of the equator, and is situated where it is out of the reach of ocean-currents, and where the conditions for the radiation of heat are most favourable, and where, indeed, the winter is the coldest on the globe (january averaging-- ° fahr.), the mean yearly temperature is two degrees and a half above zero; so that the difference between the temperature upon the equator and that at the coldest point on the sixty-seventh parallel is only about ° fahr.; whereas, if temperature were in proportion to heat received from the sun, the difference ought to be °. again, the difference between the actual january temperature on the fiftieth parallel and that upon the sixtieth is but ° fahr., whereas, the quantity of solar heat received on the fiftieth parallel during the month of january is three times that received upon the sixtieth, and the difference in temperature ought to be about ° fahr. upon any known law in the case. woeikoff, a russian meteorologist, and one of the ablest critics of mr. croll's theory, and to whom we are indebted for these facts, ascribes the greater present warmth of the northern atlantic basin, not to the astronomical cause invoked by mr. croll, but to the relatively small extent of sea in the middle latitudes of the northern hemisphere. the extent and depth of the oceans of the southern hemisphere would of themselves give greater steadiness and force to its trade-winds, and lead to a general lowering of the temperature; so that it is doubtful if the astronomical causes introduced by mr. croll, even with dr. ball's re-enforcement, would produce any appreciable effect while the distribution of land and water remains substantially what it is at the present time. still another variation in the astronomical theory has been set forth and defended by major-general a. w. drayson, f. r. a. s., instructor in the royal military school at woolwich, england. he contends that what has been called the precession of the equinoxes, and supposed to be "a conical movement of the earth's axis in a circle around a point as a centre, from which it continually decreases its distance,"[dw] is really a second rotation of the earth about its centre. as a consequence of this second rotation, he endeavours to show that the inclination of the earth's axis varies as much as °; so that, whereas the arctic and antarctic circles and the tropics extend to only about ° from the poles and the equator, respectively, about thirteen thousand five hundred years ago they extended more than °; thus bringing the frigid zones in both cases ° nearer the equator than now. this, he contends, would have produced the glacial period at the time now more generally assigned to it by direct geological evidence. [footnote dw: untrodden ground in astronomy and geology, p. .] the difficulty with this theory, even if the mathematical calculations upon which it is based are correct, would be substantially the same as those already urged against that of mr. croll. it is specially difficult to see how general drayson would account for the prolonged temperate climate in high northern latitudes during the larger part of the tertiary epoch. it will be best to turn again to the map to observe the possible effect upon the gulf stream of a geological event of which we have some definite evidence, and which is adduced by mr. upham and others as one of the important probable causes of the glacial period, namely, the subsidence of the isthmus of panama and the adjacent narrow neck of land connecting north with south america. it will be seen at a glance that a subsidence sufficient to allow the northwest current of warm water, pushed by the trade-winds along the northeast shore of south america, to pass into the pacific ocean, instead of into the gulf of mexico, would be a cause sufficient to produce the most far-reaching results; it would rob the north atlantic of the immense amount of heat and moisture now distributed over it by the gulf stream, and would add an equal amount to the northern pacific ocean, and modify to an unknown extent the distribution of heat and moisture over the lands of the northern hemisphere. the supposition that a subsidence of the isthmus of panama was among the contributing causes of the glacial period has been often made, but without any positive proof of such subsidence. from evidence which has recently come to light, however, it is certain that there has actually been considerable subsidence there in late tertiary if not in post-tertiary times. this evidence is furnished by dr. g. a. maack and mr. william m. gabb in their report to the united states government in upon the explorations for a ship-canal across the isthmus, and consists of numerous fossils belonging to existing species which are found at an elevation of feet above tide. as the dividing ridge is more than feet above tide, this does not positively prove the point, but so much demonstrated subsidence makes it easy to believe, in the absence of contradictory evidence, that there was more, and that the isthmus was sufficiently submerged to permit a considerable portion of the warm equatorial current which now passes northward from the caribbean sea and the gulf of mexico to pass into the pacific ocean. [illustration: fig. .--map showing how the land clusters about the north pole.] an obvious objection to the theory of a late tertiary or post-tertiary subsidence of the isthmus of panama presents itself in the fact that there is at present a complete diversity of species between the fish inhabiting the waters upon the different sides of the isthmus. if there had been such a subsidence, it seems natural to suppose that atlantic species would have migrated to the pacific side and obtained a permanent lodgment there, and that pacific species would have found a congenial home on the atlantic side. it must be confessed that this is a serious theoretical difficulty, but perhaps not insuperable. for it is by no means certain that colonists from the heated waters of the caribbean sea would become so permanently established upon the pacific side that they could maintain themselves there upon the re-establishment of former conditions. on the contrary, it seems reasonable to suppose that upon the re-elevation of the isthmus the northern currents, which would then resume their course, would bring back with them conditions unfavourable to the atlantic species, and favourable to the competing species which had only temporarily withdrawn from the field, and which might now be better fitted than ever to renew the struggle with their atlantic competitors. it is by no means certain, therefore, that with the re-establishment of the former conditions there would not also be a re-establishment of the former equation of life upon the two sides of the isthmus. mr. upham's theory involves also extensive elevations of land in the northern part of america; in this respect agreeing with the opinions early expressed by professors j. d. dana and j. s. newberry. of the positive indications of such northward elevations of land we have already spoken when treating in a previous chapter of the fiords and submerged channels which characterise northern europe and both the eastern and the western coasts of north america. but in working out the problem the solution is only half reached when we have got the gulf stream into the pacific ocean, and the land in the northern part of the continents elevated to some distance above its present level. there is still the difficulty of getting the moisture-laden currents from the pacific ocean to carry their burdens over the crest of the sierra nevada and rocky mountains and to deposit them in snow upon the laurentian highlands. an ingenious supplement to the theory, therefore, has been brought forward by professor carpenter, who suggests that the immense tertiary and post-tertiary lava-flows which cover so much of the area west of the rocky mountains were the cause of the accumulations of snow which formed the laurentide glacier. this statement, which at first seems so paradoxical as to be absurd, appears less so upon close examination. the extent of the outflows of lava west of the rocky mountains is almost beyond comprehension. literally, hundreds of thousands of square miles have been covered by them to a depth in many places of thousands of feet. these volcanic eruptions are mostly of late date, beginning in the middle of the tertiary and culminating probably about the time of the maximum extent of the laurentide glacier. indeed, so nearly contemporaneous was the growth of the laurentide glacier with these outflows that professor alexander winchell had, with a good deal of plausibility, suggested that the outflows of the eruptions of lava were caused by the accumulation of ice over eastern british america. his theory was that the three million cubic miles of ice which is proved to have been abstracted from the ocean and piled up over that area was so serious a disturbance of the equilibrium of the earth's crust that it caused great fissures to be opened along the lines of weakness west of the rocky mountains, and pressed the liquid lava out, as the juice is pressed out of an orange in one place by pressing upon the rind in another. professor carpenter's view is the exact reverse of professor winchell's. going back to those orographic changes which produced the lava-flows and the elevation of the northern part of british america, he thinks the problem of getting the moisture transferred from the pacific ocean to the canadian highlands is solved by the lava-flows west of the rocky mountains. this immense exudation of molten matter was accompanied by an enormous liberation of heat, which must have produced significant changes in the meteorological conditions. the moisture of the atmosphere is precipitated by means of the condensation connected with a lowering of its temperature. ordinarily, therefore, when moist winds from an oceanic area pass directly over a lofty mountain-chain, the precipitation takes place immediately, and the water finds its way back by a short course to the sea. this is what now actually occurs on the pacific coast. the sierra nevada condense nearly all the moisture; so that very little falls on the vast area extending from their summits eastward to the rocky mountains. all that region is now practically a desert land, where the evaporation exceeds the precipitation. in professor carpenter's view the heat radiated from the freshly exuded lava is supposed to have prevented the precipitation near the coast-line, and to have helped the winds in carrying it farther onward to the northeast, where it would be condensed upon the elevated highlands, upon which the snows of the great laurentide glacier were collected. it is not necessary for us to attempt to measure the amount of truth in this subsidiary hypothesis of professor carpenter, but it illustrates how complicated are the conditions which have to be considered before we rest securely upon any particular hypothesis. the unknown elements of the problem are so numerous, and so far-reaching in their possible scope, that a cautious attitude of agnosticism, with respect to the cause of the glacial period, is most scientific and becoming. still, we are ready to go so far as to say that mr. upham's theory comes nearest to giving a satisfactory account of all the phenomena, and it is to this that professor joseph le conte gives his cautious approval. summarily stated, this theory is, that the passage from the tertiary to the quaternary or glacial period was characterised by remarkable oscillations of land-level, and by corresponding changes of climate, and of ice-accumulation in northern regions; that the northern elevation was connected with subsidence in the equatorial regions; that these changes of land-level were both initiated and, in the main, continued by the interior geological forces of the globe; but that the very continental elevation which mainly brought on the glacial period added at length, in the weight of the ice which accumulated over the elevated region, a new force to hasten and increase the subsidence, which would have taken place in due time in the natural progress of the orographic oscillations already begun. professor le conte illustrates the subject by the following diagram, which, for simplicity's sake, treats the glacial epoch as one; the horizontal line, a b, represents time from the later pliocene until now; but it also represents the present condition of things both as to land-level and as to ice-accumulation. the full line, c d e, represents the oscillations of land (and presumably of temperature) above and below the present condition. the broken line represents the rise, culmination, and decline of ice-accumulation. the dotted line represents the crust-movement as it would have been if there had been no ice-accumulation. [illustration: fig. .] _succession of epochs, glacial and fluvial deposits, and_ eastern provinces and middle and southern epochs. new england. atlantic states. recent or rise of the land to its continued subsidence of terrace. present height, or coast at new york and (mostly within somewhat higher, soon southward, and rise of the period of after the departure of the mountainous belt, by traditional the ice. rivers eroding displacement along the and written their glacial fall line of the rivers. history.) flood-plains, leaving much erosion of the remnants as terraces. columbia formation since warmer climate than now, culmination of second probably due to greater glacial epoch; gulf stream, formerly sedimentation in bays, permitted southern sounds, and estuaries. mollusks to extend to gulf of st. lawrence, now represented by isolated colonies. glacial period of ice age. pleistocene period. champlain. land depressed under less subsidence in ice-weight; glacial latitude of new york and (close of the recession; continued southward than at north; second glacial deposition of upper till lower hudson valley, and epoch.) and deep flood-plains of part of its present gravel, sand and clay submarine continuation, (modified drift). above sea-level. gravel terminal moraines marking and sand deposits from pauses or readvance englacial drift in during general retreat of delaware and susquehanna ice. marine submergence. valleys, inclosing to feet on coast abundant human implements of maine, to feet in at trenton, n.j. gulf and valley of st. lawrence. second glacial. second great uplift of renewal of great the land, . to , continental elevation feet higher than now; ( . feet in latitude snow-fall again all the of new york and year; ice probably two philadelphia), of miles thick on laurentide excessive snow-fall and highlands, and extending rains, and of wide-spread somewhat farther south fluvial deposits, the here than in first columbia formation, on glaciation. lower till the coastal plain, during (ground moraine), and early part of this epoch. upper till (englacial implements of man at drift). terminal claymont, del. moraines, kames, osars, valley drift. inter-glacial. ice-sheet melted here; depression, but generally probably not more ice in not to the present level. (longest epoch arctic regions than now. deep channels cut in the of this era.) bed-rocks by the fluvial and lacustrine delaware, susquehanna, deposits of this time, potomac, and other with those of the first rivers. the appomattox glacial epoch, were deposits much eroded. eroded by the second glaciation. relative length of this epoch made known by mcgee from study of this region. first glacial. begun by high continental continental elevation; uplift, cool climate and erosion of delaware and snow-fall throughout the chesapeake bays, and of year, producing albemarle and pamlico ice-sheet. much glacial sounds. plentiful erosion and snow-fall on the southern transportation; till and appalachian mountains; stratified deposits. snows melted in summer, ended by depression of and heavy rains, land; return of warm producing broad climate, with rain; final river-floods, with melting of the ice. deposition of the isthmus of panama appomattox formation. probably submerged (gulf stream smaller), and again in second glacial epoch. _changes in altitude and climate, during the quaternary era._ mississippi basin and cordilleran region. europe and asia. northward. terracing of river including a stage of erosion and terracing valleys. northward rise considerable uplift, of stratified drift in of area of lake agassiz with return of humid river valleys. land nearly complete before conditions, alpine passage of european the ice was melted on glaciation (third flora to greenland; the country crossed by glacial epoch), and succeeded by subsidence nelson river; but rise the second great rise there, admitting warm about hudson bay is still of lakes bonneville currents to arctic sea. going on; , to , and lahontan. very minor climatic changes, years since ice-melting recent subsidence including a warmer uncovered niagara and and change to present stage than now. upper falls of st. anthony. aridity. and outer portions of indo-gangetic alluvial plain; extensive deposits of hwang ho, and destructive changes of its course. abundant deposition of depression probably final departure of the englacial drift. stone almost to the present ice-sheets; glacial implements in river level. restoration of rivers forming eskers gravels of ohio, ind., arid climate; nearly or and kames. loess and minn. laurentian quite complete deposited while the lakes held at higher evaporation of lakes region of the alps was levels, and lake bonneville and lahontan.depressed lower than agassiz formed in red formation of the "adobe"now. upper (englacial) river basin, by continuing through the till, and asar, of barrier of retreating second glacial, sweden. marine ice, with outlets over champlain, and recent submergence to lowest points of their epochs. feet in scotland, present southern scandinavia, and water-shed. marine spitzbergen. submergence to feet on southwest side of hudson bay. ice-sheet here less probable uplift , second elevation and extensive than in the feet, shown by general glaciation of first glacial epoch, and submerged valleys near northwestern europe; not generally bordered cape mendocino. second the ice-sheets of great as then by lakes in ice-sheet on british britain probably more valleys which now drain columbia and vancouver extensive than in first southward. island; local glacial epoch. glaciation of rocky oscillations of terminal moraines at mountains, cascade and ice-front; british extreme limit of the sierra range, nevada, lower and upper ice-advance, and at ten south to latitude °. the chalky, purple, and or more stages of halt or first great rise of bowlder-clays, hessle readvance in its retreat. lakes bonneville bowlder-clays. terminal and lahontan. moraines in germany. depression nearly to continental depression. recession, or probably present level southward; arid climate. long- complete departure, of more northward, but continued denudation of the ice-sheets. followed there, by the mountains: differential uplift of resulting very thick land connection between or , feet. subaërial deposits of europe and africa, great erosion of loess the "adobe." permitting southern and other modified animals to extend far drift, and of "orange intermittent volcanic northward. sand." valleys of this action in various parts epoch, partly filled of this region, erosion of the somme with later till, are throughout the valley below its oldest marked by chains of quaternary era to very implement-bearing lakes in southern recent times, and gravels. minnesota. liable to break forth again. pliocene elevation of latest rise ( . uplift and glaciation continent brought to feet) of the colorado of northwestern europe: culmination at cañon district. sierra maximum elevation. beginning of nevada and other great , feet or more quaternary era; this basin mountain-ranges (depth of the skager whole basin probably formed by immense rack); france and then uplifted . uplifts, with faulting. britain united with the feet; excessive california river- färöe islands, iceland, snow-fall and rain; courses changed; human and greenland. uplifts deposition of the bones and implements in of the himalayas and "orange sand." ice- the old river gravels, other mountain-ranges sheet south to lava-covered. ice-sheet attendant on both cincinnati and st. on british columbia; glacial epochs. louis, at length local glaciers depressing the earth's southward. crust beneath it; slackened river floods and shallow lakes, forming the loess. it is seen from the diagram that the ice-accumulation culminated at a time when the land, under the pressure of the ice-load, had already commenced to subside; and that the subsidence was greatest at a time when the pressure had already begun to diminish. but the fact that the land, after the removal of the ice-load, did not return again to its former height in the pliocene, is proof positive that there were other and more fundamental causes of crust-movement at work besides weighting and lightening. the land did not again return to its former level because the cycle of elevation, whatever its cause, which commenced in the pliocene and culminated in the early quaternary, had exhausted itself. if it had not been for the ice-load interfering with and modifying the natural course of the crust-movement determined previously and primarily by other and probably internal causes, the latter would probably have taken the course represented by the dotted line. it would have risen higher and culminated later, and its curve would have been of simpler form. we append a carefully prepared table by mr. warren upham, showing the probable changes in altitude and climate during the quaternary era.[dx] [footnote dx: on page and sequel i have summarised the reasons which lead me to discard the inter-glacial epoch, and to look upon the whole glacial period as constituting a grand unity with minor episodes. it does not yet seem to me that the duality of the period is proved. on the contrary, mr. kendall's chapter on the glacial phenomena of great britain strongly confirms my view.] on the part of many the theory here provisionally adopted will be regarded with disfavour by reason of a disinclination to supposing any great recent changes of level in the continental areas. so firmly established do the continents appear to be, that it seems like invoking an inordinate display of power to have them exalted for the sake of producing a glacial period. due reflection, however, will make it evident that within certain limits the continents are exceedingly unstable, and that they have displayed this instability to as great an extent in recent geological times as they have done in any previous geological periods. when one reflects, also, upon the size of the earth, a continental elevation of , or , feet upon a globe whose diameter is more than , , feet is an insignificant trifle. on a globe one foot in diameter it would be represented by a protuberance of barely one thousandth of an inch. a corresponding wrinkle upon a large apple would require a magnifying-glass for its detection. moreover, the activity of existing volcanoes, the immense outflows of lava which have taken place in the later geological periods, together with the uniform increase of heat as we penetrate to deeper strata in the crust of the earth--all point to a condition of the earth's interior that would make the elevations of land which we have invoked for the production of the glacial period easily credible. physicists do not, indeed, now hold to the entire fluidity of the earth's interior, but rather to a solid centre, where gravity overcomes the expansive power of heat, and maintains solidity even when the heat is intense. but between the cooling crust of the earth's exterior and a central solid core there is now believed to be a film where the influences of heat and of the pressure of gravity are approximately balanced, and the space is occupied by a half-melted or viscous magma, capable of yielding to a slow pressure, and of moving in response to it from one portion of the enclosed space to another where the pressure is for any cause relieved. as a result of prolonged enquiries respecting the nature of the forces at work both in the interior and upon the exterior of the earth, and of a careful study of the successive changes marking the geological period, we are led to believe that the continental elevations necessary to produce the phenomena of the glacial period are not only entirely possible but easily credible, and in analogy with the natural progress of geological history. in the first place, it is easy to see that two causes are in operation to produce a contraction of the earth's volume and a shortening of its diameter. heat is constantly being abstracted from the earth by conduction and radiation, but perhaps to a greater extent through ceaseless volcanic eruptions which at times are of enormous extent. it requires but a moment's thought to see that contraction of the volume of the earth's interior means that the hardened exterior crust must adjust itself by wrinkles and folds. for a long period this adjustment might show itself principally in gentle swells, lifting portions of the continents to a higher level, accompanied by corresponding subsidence in other places. this gradually accumulating strain would at length be relieved along some line of special weakness in the crust by that folding process which has pushed up the great mountain systems of the world. careful study of the principal mountain systems shows that all the highest of them are of late geological origin. indeed, the latter part of the tertiary period has been the great mountain-building epoch in the earth's history. the principal part of the elevation of the andes and the rocky mountains has taken place since the middle of the tertiary period. in europe there is indubitable evidence that the pyrenees have been elevated eleven thousand feet during the same period, and that the western alps have been elevated thirteen thousand feet in the same time. the carpathians, the western caucasus, and the himalayas likewise bear explicit evidence to the fact that a very considerable portion of their elevation, amounting to many thousand feet, has been effected since the middle of the tertiary period, while a considerable portion of this elevation of the chiefest mountain systems of the world has occurred in what would be called post-tertiary time--that is, has been coincident with a portion of the glacial period. the glacial period, however, we suppose to have been brought about, not by the specific plications in the earth's crust which have produced the mountain-chains, but by the gentler swells of larger continental areas whose strain was at last relieved by the folding and mashing together of the strata along the lines of weakness now occupied by the mountain systems. the formation of the mountains seems to have relieved the accumulating strain connected with the continental elevations, and to have brought about a subsequent subsidence. doubtless, also, correlated subsidences and elevations of the earth's crust have been aided by the transfer of the sediment from continental to oceanic areas, and, as already suggested, during the glacial period by the transfer of water evaporated from the surface of the ocean to the ice-fields of the glaciated area. for example, present erosive agencies are lowering the level of the whole mississippi basin from the alleghanies to the rocky mountains at the rate of a foot in five thousand years. all this sediment removed is being transferred to the ocean-bed. present agencies, therefore, if not counteracted, would remove the whole continent of america (whose average elevation above the sea is only feet) in less than four million years; while the great rivers which descend in all directions from the central plateau of asia are transferring sediment to the ocean from two to four times as fast as the mississippi is, and the po is transferring it from the alps to the adriatic fully seven times as fast as the mississippi is from its basin to the gulf of mexico. this rapid transfer of sediment from the continents to the ocean is producing effects in disturbing the present equilibrium of the earth's crust, which are too complicated for us fully to calculate; but it is by no means improbable that when accumulating for a considerable length of time, the ultimate results may be very marked and perhaps sudden in their appearance. the same may also be said of the accumulation of ice during the glacial period. the glaciated areas of north america and europe combined comprise about six million square miles. at a moderate estimate, the ice was three-quarters of a mile deep. here, therefore, there would be between four and five million cubic miles of water, which had first relieved the ocean-beds of the pressure of its weight, and then concentrated its force over the elevated areas of the northern hemisphere. this disturbance of the equilibrium, by the known transfer of force from one part of the earth's crust to another, certainly gives much plausibility to the theory of jamieson, winchell, le conte, and upham, that the glacial period partly contained in itself its own cure, and by the weight of its accumulated weight of ice helped to produce that depression over the glaciated area which at length rendered the accumulation of ice there impossible. this general view of the known causes in operation during the glacial period will go far towards answering an objection that has probably before this presented itself to the reader's mind. it seems clear that the glacial period in the southern hemisphere has been nearly contemporaneous with that of the northern. the glacial period proper of the southern hemisphere is long since passed. the existing glaciers of new zealand, of the southern portion of the andes mountains, and of the himalaya mountains are but remnants of those of former days. in the light of the considerations just presented, it would not seem improbable that the same causes should produce these similar effects in the northern and the southern hemisphere contemporaneously. at any rate, it would not seem altogether unlikely that the pressure of ice during the climax of the glacial period upon the northern hemisphere (which, as we have seen, there is reason to believe aided in the depression of the continent to below its present level in the latter part of the glacial period) should have contributed towards the elevation of mountains in other parts of the world, and so to the temporary enlargement of the glaciers about their summits. nor are we wholly without evidence that these readjustments of land-level which have been carried on so vigorously since the middle of the tertiary period are still going on with considerable though doubtless with diminished rapidity. there has been a re-elevation of the land in north america since the glacial period amounting to feet upon the coast of maine, feet in the vicinity of montreal, from , to , feet in the extreme northern part of the continent, and in scandinavia to the extent of feet. in portions of scandinavia the land is now rising at the rate of three feet in a century. other indications of even the present instability of the earth's surface occur in numbers too numerous to mention.[dy] [footnote dy: for a convincing presentation of the views here outlined, together with abundant references to literature, see mr. warren upham's appendix to the author's ice age in north america.] but, while we are increasingly confident that the main causes of the glacial period have been changes in the relative relation of land-levels connected with diversion of oceanic currents, it is by no means impossible, as wallace[dz] and others have suggested, that these were combined with the astronomical causes urged by drs. croll and geikie. by some this combination is thought to be the more probable, because of the extreme recentness of the close of the glacial period, as shown by the evidence which will be presented in the following chapter. the continuance of glaciers in the highlands of canada, down to within a few thousand years of the present time, coincides in a remarkable manner with the last occurrence of the conditions favourable to glaciation upon mr. croll's theory, which took place about eleven thousand years ago. [footnote dz: see island life, chapters viii and ix.] chapter x. the date of the glacial period. in approaching the subject of glacial chronology, we are compelled to recognise at the outset the approximate character of all our calculations. still, we shall find that there are pretty well-defined limits of time beyond which it is not reasonable to place the date of the close of the glacial period; and, where exact figures cannot be determined, it may yet be of great interest and importance to know something near the limits within which our speculations must range. for many years past mr. croll's astronomical theory as to the cause of the glacial period has been considered in certain circles as so nearly established that it has been adopted by them as a chronological table in which to insert a series of supposed successive glacial epochs which are thought to have characterised not merely the quaternary epoch but all preceding geological eras. what we have already said, however, respecting the weakness of mr. croll's theory is probably sufficient to discredit it as a chronological apparatus. we will therefore turn immediately to the more tangible evidences bearing upon the subject. the data directly relating to the length of time which separates the present from the glacial period are mainly connected with two classes of facts: . the amount of erosion which has been accomplished by the river systems since the glacial period; and . the amount of sedimentation which has taken place in lakes and kettle-holes. we will consider first the evidence from erosion. [illustration: fig. .--diagram of eccentricity and precession: abscissa represents time and ordinates, degrees of eccentricity and also of cold. the dark and light shades show the warmer and colder winters, and therefore indicate each , years, the whole representing a period of , years.] the gorge below niagara falls affords an important chronometer for measuring the time which has elapsed since a certain stage in the recession of the great north american ice-sheet. as already shown, the present niagara river is purely a post-glacial line of drainage;[ea] the preglacial outlet to lake erie having been filled up by glacial deposits, so that, on the recession of the ice, the lowest level between lake erie and lake ontario was in the line of the trough of the present outlet. but, from what has already been said, it also appears that the niagara river did not begin to flow until considerably after the ice-front had withdrawn from the escarpment at queenston, where the river now emerges from its cañon to the low shelf which borders lake ontario. for a considerable period afterwards the ice continued to block up the easterly and northerly outlets through the valleys of the mohawk and of the st. lawrence, and held the water in front of the ice up to the level of the passes leading into the mississippi valley. niagara river, of course, was not born until these ice-barriers on the east and northeast melted away sufficiently to allow the drainage to take its natural course. [footnote ea: see above, p. _et seq._] [illustration: fig. .--map of the niagara river below the falls, showing the buried channel from the whirlpool to st. davids. small streams, _a_, _b_, _c_, fall into the main gorge over a rocky escarpment. no rock appears in the channel at _d_, but the rocky escarpment reappears at _e_.] of these barriers, that across the mohawk valley doubtless gave way first. this would allow the confluent waters of this great glacial lake to fall down to the level of the old outlet from the basin of lake ontario into the mohawk valley, in the vicinity of home, n. y. the moment, however, that the water had fallen to this level, the plunging torrents of niagara would begin their work; and the gorge extending from queenston up to the present falls is the work done by this great river since that point of time in the glacial period when the ice-barrier across the mohawk valley broke away. the problem is therefore a simple one. considering the length of this gorge as the dividend, the object is to find the rate of annual recession; this will be the divisor. the quotient will be the number of years which have elapsed since the ice first melted away from the mohawk valley. we are favoured in our calculation by the simplicity of the geologic arrangement. the strata at niagara dip slightly to the south, but not enough to make any serious disturbance in the problem. that at the surface, over which the water now plunges, consists of hard limestone, seventy or eighty feet in thickness, and this is continuous from the falls to the face of the escarpment at queenston, where the river emerges from the gorge. immediately underneath this hard superficial stratum there is a stratum of soft rock, of about the same thickness, which disintegrates readily. as a consequence, the plunging water continually undermines the hard stratum at the surface, and prepares the way for it to fall down, from time to time, in huge blocks, which are, in turn, ground to powder by the constant commotion in which they are kept, and thus the channel is cleared of _débris_. [illustration: fig. .--section of strata along the niagara gorge from the falls to the lake: , , strata of hard rock; , , of soft rock.] below these two main strata there is considerable variation in the hardness of the rock, as shown in the accompanying diagram, where and are hard strata separated by a soft stratum. in view of this fact it seems probable that, for a considerable period in the early part of the recession, instead of there being simply one, there was a succession of cataracts, as the water unequally wore back through the harder strata, numbered , , and ; but, after having receded half the distance, these would cease to be disturbing influences, and the problem is thus really the simple one of the recession through the strata numbered and , which are continuous. so uniform in consistency are these throughout the whole distance, that the rate of recession could never have been less than it is now. we come, therefore, to the question of the rapidity with which the falls are now receding. in sir charles lyell and professor james hall (the state geologist of new york) visited the falls together, and estimated that the rate of recession could not be greater than one foot a year, which would make the time required about thirty-five thousand years. but lyell thought this rate was probably three times too large; so that he favoured extending the time to one hundred thousand years. before this the eminent french geologist desor had estimated that the recession could not have been more than a foot in a century, which would throw the beginning of the gorge back more than three million years. but these were mere guesses of eminent men, based on no well-ascertained facts; while mr. bakewell, an eminent english geologist, trusting to the data furnished him by the guides and the old residents of niagara, had, even then, estimated that the rate of recession was as much as three feet a year, which would reduce the whole time required to about ten thousand years. but the visit of lyell and hall in led to the beginning of more accurate calculations. professor hall soon after had a trigonometrical survey of the falls made, from which a map was published in the state geological report. from this and from the monuments erected, we have had since that time a basis of comparison in which we could place absolute confidence. in recent years three surveys have been made: the first by the new york state geologists, in ; and the third by mr. r. s. woodward, the mathematician of the united states geological survey, in . the accompanying map shows the outlines of the falls at the time of these three measurements, from to . according to mr. woodward, "the length of the front of the horseshoe fall is twenty-three hundred feet. between and four and a quarter acres of rock were worn away by the recession of the falls. between and a little over one acre and a third disappeared in a similar manner, making in all, from to , about five and a half acres removed, and giving an annual rate of recession of about two feet and a half per year for the last forty-five years. but in the central parts of the curve, where the water is deepest, the horseshoe fall retreated between two hundred and two hundred and seventy-five feet in the eleven years between and ." [illustration: fig. .--map showing the recession of the horseshoe falls since , as by survey mentioned in the text (pohlman). (by courtesy of the american institute of mining engineers.)] it will be perceived that the recession in the centre of the horseshoe is very much more rapid than that nearer the margin; yet this rate at the centre is more nearly the standard of calculation than is that near the margin, for the gorge constantly tends to enlarge itself below the falls, and so gradually to bring itself into line with the full-formed channel. taking all things into account, mr. woodward and the other members of the geological survey thought it not improbable that the average rate of actual recession in the horseshoe fall was as great as five feet per annum; and that, if we can rely upon the uniformity of the conditions in the past, seven thousand years is as long a period as can be assigned to its commencement. the only condition in the problem about which there can be much chance of question relates to the constancy of the volume of water flowing in the niagara channel. mr. gilbert had suggested that, as a consequence of the subsidence connected with the closing portions of the glacial period, the water of the great lakes may have been largely diverted from its present outlet in niagara river and turned northeastward, through georgian bay, french river, and lake nipissing, into a tributary of the ottawa river, and so carried into the st. lawrence below lake ontario. of this theory there is also much direct evidence. a well-defined shore line of rounded pebbles extends, at an elevation of about fifty feet, across the col from lake nipissing to the head-waters of the mattawa, a tributary of the ottawa; while at the junction with the ottawa there is an enormous delta terrace of boulders, forming a bar across the main stream just such as would result from mr. gilbert's supposed outlet. but this outlet was doubtless limited to a comparatively few centuries, and dr. robert bell thinks the evidence still inconclusive.[eb] [footnote eb: see bul. geol. soc. am., vol. iv, pp. - , vol. v, pp. - .] a second noteworthy glacial chronometer is found in the gorge of the mississippi river, extending from the falls of st. anthony, at minneapolis, to its junction with the preglacial trough of the old mississippi, at fort snelling, a distance likewise of about seven miles. above fort snelling the preglacial gorge is occupied by the minnesota river, and, as we have before stated, extends to the very sources of this river, and is continuous with the southern portion of the valley of the trough of the red river of the north. before the glacial period the drainage of the present basin of the upper mississippi joined this main preglacial valley, not at fort snelling, but some little distance above, as shown upon our map.[ec] this part of the preglacial gorge became partially filled up with glacial deposits, but it can be still traced by the lakelets occupying portions of the old depression, and by the records of wells which have been sunk along the line. when the ice-front had receded beyond the site of minneapolis, the only line of drainage left open for the water was along the course of the present gorge from minneapolis to fort snelling. [footnote ec: see above, p. .] here, as at niagara, the problem is comparatively simple. the upper strata of rock consist of hard limestone, which is underlaid by a soft sandstone, which, like the underlying shale at niagara, is eroded faster than the upper strata, and so a perpendicular fall is maintained. the strata are so uniform in texture and thickness that, with the present amount of water in the river, the rate of recession of the falls must have been, from the beginning, very constant. if, therefore, the rate can be determined, the problem can be solved with a good degree of confidence. fortunately, the first discoverer of the cataract--the catholic missionary hennepin--was an accurate observer, and was given to recording his observations for the instruction of the outside world and of future generations. from his description, printed in amsterdam in , professor n. h. winchell is able to determine the precise locality of the cataract when discovered in . again, in the catholic missionary carver visited the falls, and not only wrote a description, but made a sketch (found in an account of his travels, published in london in ) which confirms the inferences drawn from hennepin's narrative. the actual period of recession, however (which professor winchell duly takes into account), extends only to the year , at which time such artificial changes were introduced as to modify the rate of recession and disturb further calculations. but between and the falls had evidently receded about feet. between and the recession had been feet. the average rate is estimated by professor winchell to be about five feet per year, and the total length of time required for the formation of the gorge above fort snelling is a little less than eight thousand years, or about the same as that calculated by messrs. woodward and gilbert for the niagara gorge. to these calculations of professor winchell it does not seem possible to urge any valid objection. it does not seem credible that the amount of water in the mississippi should ever have been less than now, while during the continuance of the ice in the upper portion of the mississippi basin the flow of water was certainly far greater than now. if any one is inclined to challenge professor winchell's interpretation of the facts, even a hasty visit to the locality will suffice to produce conviction. the comparative youth of the gorge from fort snelling up to minneapolis is evident: . from its relative narrowness, when compared with the main valley below. this is represented by the shading upon the map. the gorge from fort snelling up is not old enough to have permitted much enlargement by the gradual undermining of the superficial strata on either side, which slowly but constantly goes on. . from the abruptness with which it merges into the preglacial valley of the minnesota-mississippi. the opening at fort snelling is not y-shaped, as in gorges where there has been indefinite time for the operation of erosive agencies. . furthermore, the precipices lining the post-glacial gorge above fort snelling are far more abrupt than those in the preglacial valley below, and they give far less evidence of weathering. . still, again, the tributary streams, like the minnehaha river, which empty into the mississippi between fort snelling and minneapolis, flow upon the surface, and have eroded gorges of very limited extent; whereas, below fort snelling, the small streams have usually either found underground access to the river or occupy gorges of indefinite extent. the above estimates, setting such narrow limits to post-glacial time in america, will seem surprising only to those who have not carefully considered the glacial phenomena of various kinds to be observed all over the glaciated area. as already said, the glaciated portion of north america is a region of waterfalls, caused by the filling up of old channels with glacial _débris_, and the consequent diversion of the water-courses. by this means the streams in countless places have been forced to fall over precipices, and to begin anew their work of erosion. waterfalls abound in the glaciated region because post-glacial time is so short. give these streams time enough, and they will wear their way back to their sources, as the preglacial streams had done over the same area, and as similar streams have done outside the glaciated region. upon close observation, it will be found that the waterfalls in america are nearly all post-glacial, and that their work of erosion has been confined to a very limited time. a fair example is to be seen at elyria, ohio, in the falls of black river, one of the small streams which empty into lake erie from the south. its post-glacial gorge, worn in sandstone which overlies soft shale, is only about two thousand feet in length, and it has as yet made no approach toward a v-shaped outlet. the same impression of recent age is made by examining the outlets of almost any of the lakes which dot the glaciated area. the very reason of the continued existence of these lakes is that they have not had time enough to lower their outlets sufficiently to drain the water off, as has been done in all the unglaciated region. in many cases it is easy to see that the time during which this process of lowering the outlets has been going on cannot have been many thousand years. the same impression is made upon studying the evidences of post-glacial valley erosion. ordinary streams constantly enlarge their troughs by impinging against the banks now upon one side and now upon the other, and transporting the material towards the sea. it is estimated by wallace that nine-tenths of the sedimentary material borne along by rivers is gathered from the immediate vicinity of its current, and goes to enlarge the trough of the stream. upon measuring the cubical contents of many eroded troughs of streams in the glaciated region, and applying the tables giving the average amount of annual transportation of sediment by streams, we arrive at nearly the same results as by the study of the recession of post-glacial waterfalls. professor l. e. hicks, of granville, ohio, has published the results of careful calculations made by him, concerning the valley of raccoon creek in licking county, ohio.[ed] these show that fifteen thousand years would be more than abundant time for the erosion of the immediate valley adjoining that small stream. i have made and published similar calculations concerning plum creek, at oberlin, in lorain county, ohio.[ee] like raccoon creek, this has its entire bed in glacial deposits, and has had nothing else to do since its birth but to enlarge its borders. the drainage basin of the creek covers an area of about twenty-five square miles. its main trough averages about twenty feet in depth by five hundred in width, along a distance of about ten miles. from the rate at which the stream is transporting sediment, it is incredible that it could have been at work at this process more than ten thousand years without producing greater results. [footnote ed: see baptist quarterly for july. .] [footnote ee: see ice age in north america, p. .] calculations based upon the amount of sediment deposited since the retreat of the ice-sheet point to a like moderate conclusion. when one looks upon the turbid water of a raging stream in time of flood, and considers that all the sediment borne along will soon settle down upon the bottom of the lake into which the stream empties, he can but feel surprised that the "wash" of the hills has not already filled up the depression of the lake. it certainly would have done so had the present condition of things existed for an indefinite period of time. naturally, while prosecuting the survey of the superficial geology of minnesota, mr. upham was greatly impressed by the continued existence of the innumerable lakelets that give such a charm to the scenery of that state. every day's investigations added to the evidence that the lapse of time since the ice age must have been comparatively brief, since, otherwise, the rains and streams would have filled these basins with sediment, and cut outlets low enough to drain them dry, for in many instances he could see such changes slowly going forward.[ef] [footnote ef: minnesota geological report for , p. .] [illustration: fig. .--section of kettle-hole near pomp's pond, andover, massachusetts (see text). (for general view of the situation, see fig. , p. .)] some years ago i myself made a careful estimate of the amount of deposition and vegetable accumulation which had taken place in a kettle-hole near pomp's pond, in andover, mass. the diameter of the depression at the rim was feet. the inclination of the sides was such that the extreme depression of the apex of the inverted cone could not have been more than seventy feet; yet the accumulation of peat and sediment only amounted to a depth of seventeen feet. the total amount of material which had accumulated would be represented by a cone ninety-six feet in diameter at the base and seventeen feet at the apex, which would equal only a deposit of about five feet over the present surface of the bottom. it is easy to see that ten thousand years is a liberal allowance of time for the accumulation of five feet of sediment in the bottom of an enclosure like a kettle-hole, for upon examination it is clear that whatever insoluble material gets into a kettle-hole must remain there, since there is no possible way by which it can get out. now five feet is sixty inches, and if this amount has been six thousand years in accumulating, that would represent a rate of an inch in one hundred years, while, if it has been twelve thousand years in accumulation, the rate will be only one two-hundredth of an inch per year, a film so small as to be almost inappreciable. if we may judge from appearance, the result would not be much different in the case of the tens of thousands of kettle-holes and lakelets which dot the surface of the glaciated region. in the year dr. e. andrews, of chicago, made an important series of calculations concerning the rate at which the waters of lake michigan are eating into the shores and washing the sediment into deeper water or towards the southern end of the lake. with reference to the erosion of the shores, it appears from the work of the united states coast survey that a shoulder, covered with sixty feet of water, representing the depth at which wave-action is efficient in erosion, extends outward from the west shore a distance of about three miles, where the sounding line reveals the shore of the deeper original lake as it appeared upon the first withdrawal of the ice. from a variety of observations the average rate at which the erosion of the bluffs is proceeding is found to be such that the post-glacial time cannot be more than ten thousand years, and probably not more than seven thousand. an independent mode of calculating this period is afforded by the accumulations of sand at the south end of the lake, to which it is constantly drifting by the currents of water propelled against the shores by the wind; for the body of water in the lake is moving southward along the shores towards the closed end in that direction, there being a returning current along the middle of the lake. all the railroads approaching chicago from the east pass through these sand deposits, and few of the observant travellers passing over the routes can have failed to notice the dunes into which the sand has been drifted by the wind. now, all the material of these dunes and sand-beaches has been washed out of the bluffs to the northward by the process already mentioned, and has been slowly transferred by wave-action to its present position. it is estimated that south of chicago and grand haven, this wave-transported sand amounts to , , , cubic yards. this occupies a belt curving around the south end about ten miles wide and one hundred miles long. the rate at which the sand is moving southward along the shore is found by observing the amount annually arrested by the piers at chicago, grand haven, and michigan city. this equals , cubic yards for a year, which can scarcely be more than one quarter or one fifth of the total amount in motion. at this rate, the sand accumulations at the southern end of the lake would have been produced in a little less than seven thousand years. "if," says dr. andrews, "we estimate the total annual sand-drift at only twice the amount actually stopped by the very imperfect piers built--which, in the opinion of the engineers, is setting it far too low--and compare it with the capacity of the clay-basin of lake michigan, we shall find that, had this process continued one hundred thousand years the whole south end of lake michigan, up to the line connecting chicago and michigan city, would have been full and converted into dry land twenty-five thousand years ago, and the coast-line would now be found many miles north of chicago."[eg] [footnote eg: southall's recent origin of man, p. .] it is proper to add a word in answer co an objection which may arise in the reader's mind, for it will doubtless occur to some to ask why this sand which is washed out by the waves from the bluffs is not carried inward towards the deeper portion of the trough of the lake, thus producing a waste which would partly counteract the forces of accumulation at the south end. the answer is found in the fact that the south end of lake michigan is closed, and that the currents set in motion by the wind are such that there is no off-shore motion sufficient to move sand, and, as a matter of fact, dredgings show that the sand is limited to the vicinity of the shore. by comparing the eroded cliffs upon michigan and the other great lakes with what occurs in similar situations about the glacial lake agassiz, we obtain an interesting means of estimating the comparative length of time occupied by the ice-front in receding from the canadian border to hudson bay. as we have seen, lake agassiz occupied a position quite similar in most respects to lake michigan. its longest diameter was north and south, and the same forces which have eroded the cliffs of lake michigan and piled up sand-dunes at its southern end would have produced similar effects upon the shores of lake agassiz, had its continuance been anywhere near as long as that of the present lake michigan has been. but, according to mr. upham, who has most carefully surveyed the whole region, there are nowhere on the shores of the old lake agassiz any evidence of eroded cliffs at all to be compared with those found upon the present great lakes, while there is almost an entire lack of sand deposits about the south end such as characterise the shore of lake michigan. "the great tracts of dunes about the south end of lake michigan belong," as upham well observes, "wholly to beach accumulations, being sand derived from erosion of the western and eastern shores of the lake.... but none of the beaches of our glacial lakes are large enough to make dunes like those on lake michigan, though the size and depth of lake agassiz, its great extent from north to south, and the character of its shores, seem equally favorable for their accumulation. it is thus again indicated that the time occupied by the recession of the ice-sheet was comparatively brief."[eh] [footnote eh: proceedings of the boston society of natural history, vol. xxiv, p. ; upham's glacial lakes in canada, in bulletin of the geological society of america, vol. ii, p. .] from mr. upham's conclusions it would seem that if ten thousand years be allowed for the post-glacial existence of lake michigan, one tenth of that period would be more than sufficient to account for the cliffs, deltas, beaches, and other analogous phenomena about lake agassiz. in other words, the duration of lake agassiz could not have been more than a thousand years, which gives us a measure of the rate at which the recession of the ice-front went on after it had withdrawn to the international boundary. the distance from there to the mouth of nelson river is about miles. the recession of the ice-front over that area proceeded, therefore, at the average rate of about half a mile per year. there are many evidences that the main period of glaciation west of the rocky mountains was considerably later than that in the eastern part of the continent. a portion of the facts pointing to this conclusion have been well stated by mr. george f. becker, of the united states geological survey. "no one," he says, "who has examined the glaciated regions of the sierra can doubt that the great mass of the ice disappeared at a very recent period. the immense areas of polished surfaces fully exposed to the severe climate of say from , to , feet altitude, the insensible erosion of streams running over glaciated rocks, and the freshness of erratic boulders are sufficient evidence of this. there is also evidence that the glaciation began at no very distant geologic date. as professor whitney pointed out, glaciation is the last important geological phenomenon and succeeded the great lava flows. there is also much evidence that erosion has been trifling since the commencement of glaciation, excepting under peculiar circumstances. east of the range, for example, at virginia city, andesites which there is every reason to suppose preglacial have scarcely suffered at all from erosion, so that depressions down which water runs at every shower are not yet marked with water-courses, while older rocks, even of tertiary age and close by, are deeply carved. the rainfall at virginia city is, to be sure, only about ten inches, so that rock would erode only say one third as fast as on the california coast; but even when full allowance is made for this difference, it is clear that these andesites must be much younger than the commencement of glaciation in the northeastern portion of the continent as usually estimated. so, too, the andesites near clear lake, in california, though beyond a doubt preglacial, have suffered little erosion, and one of the masses, mount konocti (or uncle sam), has nearly as characteristic a volcanic form as mount vesuvius."[ei] [footnote ei: bulletin of the geological society of america, vol. ii, pp. , .] this view of mr. becker is amply sustained by many other obvious facts, some of which may be easily observed by tourists who visit the yosemite park. the freedom of the abutting walls of this cañon from talus, as well as the freshness of the glacial scratches upon both the walls and the floor of the tributary cañons, all indicate a lapse of centuries only, rather than of thousands of years, since their occupation by glacial ice. the freshness of the high-level terraces surrounding the valleys of great salt lake, in utah, and of pyramid and north carson lakes, in nevada, and the small amount of erosion which has taken place since the formation of these terraces, point in the same direction--namely, to a very recent date for the glaciation of the pacific coast. we have already detailed the facts concerning the formation of these terraces and the evidence of their probable connection with the glacial period. it is sufficient, therefore, here to add that, according to mr. russell and mr. gilbert (two of the most eminent members of the united states geological survey, who have each published monographs minutely embodying the results of their extensive observations in this region), the erosion of present streams in the beds which were deposited during the enlargement of the lakes is very slight, and the modification of the shores since the formation of the high terraces has been insignificant. according to mr. gilbert: "the bonneville shores are almost unmodified. intersecting streams, it is true, have scored them and interrupted their continuity for brief spaces; but the beating of the rain has hardly left a trace. the sea-cliffs still stand as they first stood, except that frost has wrought upon their faces so as to crumble away a portion and make a low talus at the base. the embankments and beaches and bars are almost as perfect as though the lake had left them yesterday, and many of them rival in the symmetry and perfection of their contours the most elaborate work of the engineer. there are places where boulders of quartzite or other enduring rock still retain the smooth, glistening surfaces which the waves scoured upon them by clashing against them the sands of the beach. "when this preservation is compared with that of the lowest tertiary rocks of the region--the pliocene beds to which king has given the name humboldt--the difference is most impressive. the pliocene shore-lines have disappeared. "the deposits are so indurated as to serve for building-stone. they have been upturned in many places by the uplifting of mountains. elsewhere they have been divided by faults, and the fragments, dissevered from their continuation in the valley, have been carried high up on the mountain-flanks, where erosion has carved them in typical mountain forms.... the date of the bonneville flood is the geologic yesterday, and, calling it yesterday, we may without exaggeration refer the pliocene of utah to the last decade; the eocene of the colorado basin to the last century, and relegate the laying of the potsdam sandstone to prehistoric times."[ej] [footnote ej: second annual report of the united states geological survey, p. .] mr. russell adds to this class of evidence that of the small extent to which the glacial striæ have been effaced since the withdrawal of the ice from the borders of these old lakes: "the smooth surfaces are still scored with fine, hair-like lines, and the eye fails to detect more than a trace of disintegration that has taken place since the surfaces received their polish and striation.... it seems reasonable to conclude that in a severe climate like that of the high sierra it" (the polish) "could not remain unimpaired for more than a few centuries at the most."[ek] [footnote ek: see also mr. upham in american journal of science, vol. xli, pp. , .] europe does not seem to furnish so favourable opportunities as america for estimating the date of the glacial period; still it is not altogether wanting in data bearing upon the subject. some of the caves in which palæolithic implements were found associated with the bones of extinct animals in southern england contain floors of stalagmite which have been thought by some to furnish a measure of the time separating the deposits underneath from those above. this is specially true in the case of kent's cavern, near torquay, which contains two floors of stalagmite, the upper one almost continuous and varying in thickness from sixteen inches to five feet, the lower one being in places twelve feet thick, underneath which human implements were found. but it is difficult to determine the rate at which stalagmite accumulates. as is well known, this deposit is a form of carbonate of lime, and accumulates when water holding the substance in solution drops down upon the surface, where it is partially evaporated. it then leaves a thin film of the substance upon the floor. the rate of the accumulation will depend upon both the degree to which the water is saturated with the carbonate and upon the quantity of the water which percolates through the roof of the cavern. these factors are so variable, and so dependent upon unknown conditions in the past, that it is very difficult to estimate the result for any long period of time. occasionally a quarter of an inch of stalagmite accretion has been known to take place in a cavern in a single year, while in kent's cavern, over a visitor's name inscribed in the year , a film of stalagmite only a twentieth of an inch in thickness has accumulated. if, therefore, we could reckon upon a uniformity of conditions stretching indefinitely back into the past, we could determine the age of these oldest remains of man in kent's hole by a simple sum in arithmetic, and should infer that the upper layer of stalagmite required , years, and the lower , years, for their growth, which would carry us back more than , years, and some have not hesitated to affix as early a date as this to these lowest implement-bearing gravels. but other portions of the cave show an actual rate of accretion very much larger. six inches of stalagmite is there found overlying some remains of romano-saxon times which cannot be more than , years old. assuming this as the uniform rate, the total time required for the deposit of the stalagmitic floors would still be about , years. but, as we have seen, the present rates of deposition are probably considerably less than those which took place during the moister climate of the glacial epoch. still, even by supposing the rate to be increased fourfold, the age of this lower stratum would be reduced to only , years. so that, as mr. james geikie well maintains, "even on the most extravagant assumption as to the former rate of stalagmitic accretion, we shall yet be compelled to admit a period of many thousands of years for the formation of the stalagmitic pavements in kent's cavern."[el] we should add, however, that there is much well-founded doubt whether the implements found in the lowest stratum were really in place, since, according to dr. evans, "owing to previous excavations and to the presence of burrowing animals, the remains from above and below the stalagmite have become intermingled."[em] [footnote el: prehistoric europe, p. .] [footnote em: stone and flint implements, p. .] an attempt was made by m. morlot in switzerland to obtain the chronology of the glacial period by studying the deltas of the streams descending the glaciated valleys. he paid special attention to that of the tinière, a stream which flows into lake geneva near villeneuve. the modern delta of this stream consists of gravel and sand deposited in the shape of a flattened cone, and investigations upon it were facilitated by a long railroad cutting through it. "three layers of vegetable soil, each of which must at one time have formed the surface of the cone, have been cut through at different depths."[en] in the upper stratum roman tiles and a coin were found; in the second stratum, unvarnished pottery and implements of bronze; while in the lower stratum, at a depth of nineteen feet from the surface, a human skull was found, to which morlot assigned an age of from , to , years. [footnote en: lyell's antiquity of man, p. .] but dr. andrews, after carefully revising the data, felt confident that the time required for the whole deposit of this lower delta was not more than , years, and that the oldest human remains in it, which were about half way from between the base and the surface of the cone, were probably not more than , years old. still, the significance of this estimate principally arises from the relation of the modern delta to older deltas connected with the glacial period. above this modern delta, formed by the river in its present proportions, there is another, more ancient, about ten times as large, whose accumulation doubtless took place upon the final retreat of the ice from lake geneva. no remains of man have been found in this, but it doubtless corresponds in age with the high-level gravels in the valley of the somme, in which the remains of man and the mammoth, together with other extinct animals, have been found. we do not see, however, that any very definite calculation can be made concerning the time required for its deposition. lyell was inclined to consider it ten times as old as the modern delta, simply upon the ground of its being ten times as large. on morlot's estimate of the age of the modern delta, therefore, the retreat of the ice whose melting torrents deposited the upper delta would be fixed at , years ago, and upon dr. andrews's calculation, at about , . but it is evident that the problem is not one of simple multiplication. the floods of water which accompanied the melting back of the ice from the upper portions of this valley must have been immensely larger than those of the present streams, and their transporting power immensely greater still. hence we do not see that any conclusions can be drawn from the deltas of the tinière to give countenance to extreme views concerning the date of the close of the glacial period.[eo] [footnote eo: lyell's antiquity of man, p. .] in the valley of the somme the chronological data relating to the glacial period, and indicating a great antiquity for man, have been thought to be more distinct than anywhere else in europe. as already stated, it is the prevalent opinion that since man first entered the valley, in connection with the mammoth and the other extinct animals characteristic of the glacial period, the trough of the somme, about a mile in width and a hundred feet in depth, has been eroded by the drainage of its present valley. an extensive accumulation of peat also has taken place along the bottom of the trough of the river since it was originally eroded to its present level. this substance occurs all along the bottom of the valley from far above amiens to the sea, and is in some places more than thirty feet in depth. the animal and vegetable remains in it all belong to species now inhabiting europe. the depth of the peat indicates that when it was formed the land stood at a slightly higher elevation than now, for the base of the stratum is now below the sea-level, while the peat is of fresh-water origin, and, according to dr. andrews,[ep] is formed from the vegetable accumulations connected with forest growths. when, therefore, the country was covered with forests, as it was in prehistoric times, the accumulation must have proceeded with considerable rapidity. this inference is confirmed by the occurrence in the peat of prostrate trunks of oak, four feet in diameter, so sound that they were manufactured into furniture. the stumps of trees, especially of the birch and alder, were also found in considerable number, standing erect where they grew, sometimes to a height of three feet. now, as dr. andrews well remarks, it is evident that, in order to prevent these stumps and prostrate trunks from complete decay, the accumulation of peat must have been rapid. from certain roman remains found six feet and more beneath the surface, he estimates that the accumulation since the roman occupation has been as much as six inches a century, at which rate the whole would take place in somewhat over , years. [footnote ep: american journal of science, october, .] still, if we accept this estimate, we have obtained but a starting-point from which to estimate the age of the high-level gravels in which palæolithic implements were found; for, if we accept the ordinary theory, we must add to this the time required for the river to lower its bed from eighty to a hundred feet, and to carry out to the sea the contents of its wide trough. but, as already shown, the glacial period was, even in the north of france, a time of great precipitation and of a considerable degree of cold, when ice formed to a much greater extent than now upon the surface of the somme. the direct evidence of this consists in the boulders mingled with the high-level gravel which are of such size as to require floating ice for their transportation. in addition to the natural increase in the eroding power of the somme brought about by the increase in its volume, on account of the greater precipitation in the glacial age, there would also be, as prestwich has well shown, a great increase in rate through the action of ground-ice, which plays a very important part in the river erosion of arctic countries, and in all probability did so during the glacial period in the valley of the somme. "when the water is reduced to and below ° fahr., although the rapid motion may prevent freezing on the surface for a time, any pointed surfaces at the bottom of the river, such as stones and boulders, will determine (as is the case with a saturated saline solution) a sort of crystallisation, needles of ice being formed, which gradually extend from stone to stone and envelop the bodies with which they are in contact. by this means the whole surface of a gravelly river-bed may become coated with ice, which, on a change of temperature, or of atmospheric pressure, or on acquiring certain dimensions and buoyancy, rises to the surface, bringing with it the loose materials to which it adhered. colonel jackson remarks, in speaking of this bottom-ice, that 'it frequently happens that these pieces, in rising from the bottom, bring up with them sand and stones, which are thus transported by the current.... when the thaw sets in the ice, becoming rotten, lets fall the gravel and stones in places far distant from those whence they came.' "again, baron wrangell remarks that, 'in all the more rapid and rocky streams of this district [northern siberia] the formation of ice takes place in two different manners; a thin crust spreads itself along the banks and over the smaller bays where the current is least rapid; but the greater part is formed in the bed of the river, in the hollows among the stones, where the weeds give it the appearance of a greenish mud. as soon as a piece of ice of this kind attains a certain size, it is detached from the ground and raised to the surface by the greater specific gravity of the water; these masses, containing a quantity of gravel and weeds, unite and consolidate, and in a few hours the river becomes passable in sledges instead of in boats.' similar observations have been made in america; but instances need not be multiplied, as it is a common phenomenon in all arctic countries, and is not uncommon on a small scale even in our latitudes. "the two causes combined--torrential river-floods and rafts of ground-ice, together with the rapid wear of the river cliffs by frost--constituted elements of destruction and erosion of which our present rivers can give a very inadequate conception; and the excavations of the valleys must have proceeded with a rapidity with which the present rate of erosion cannot be compared; and estimates of time founded on this, like those before mentioned on surface denudation, are therefore not to be relied upon."[eq] [footnote eq: prestwich's geology, vol. ii, pp. , .] speaking a little later of taking the present rates of river erosion as a standard to estimate the chronology of the glacial period, the same high authority remarks: "it no more affords a true and sufficient guide than it would be to take the tottering paces and weakened force of an old man as the measure of what that individual was, and what he could do, in his robust and active youth. it may be right to take the effects at present produced by a given power as the known quantity, a, but it is equally indispensable, in all calculations relative to the degree of those forces in past times, to take notice of the unknown quantity, x, although this, in the absence of actual experience, which cannot be had, can only be estimated by the results and by a knowledge of the contemporaneous physical conditions. it may be a complicated equation, but it is not to be avoided.[er] [footnote er: prestwich's geology, vol. ii, pp. , .] "in this country and in the north of france broad valleys have been excavated to the depth of from about eighty to a hundred and fifty feet in glacial and post-glacial times. difficult as it is by our present experience to conceive this to have been effected in a comparatively short geological term, it is equally, and to my mind more, difficult to suppose that man could have existed eighty thousand years or more, and that existing forms of our fauna and flora should have survived during two hundred and forty thousand years without modification or change."[es] [footnote es: ibid., p. .] the discussion of the age of the high-level river gravels of the somme and other streams in northwestern europe is not complete, however, without considering another possibility as to the mode of their deposition. the conclusion to which mr. alfred tylor arrived, after a prolonged and careful study of the subject, was that the main valleys of the somme and other streams in northern france and southern england were preglacial in their origin, and that the accumulations of gravel at high levels along their margin were due to enormous floods which characterised the closing portion of the great ice age, which he denominated the pluvial period.[et] the credibility of floods large enough to accomplish the results manifest in the valley of the somme is supported by reference to a flood which occurred on the mulleer river, in india, in , when a stream, which is usually insignificant, was so swollen by a rainfall of a single day that it rose high enough to sweep away an iron bridge the bottoms of whose girders were sixty-five feet above high-water mark. one iron girder weighing eighty tons was carried two miles down the river, and nearly buried in sand. the significance of these facts is enhanced by observing also that for fifteen miles above the bridge the fall of the river only averaged ten feet per mile. floods to this extent are not uncommon in india. during the glacial period spring freshets, must have been greatly increased by the melting of a large amount of snow and ice which had accumulated during the winter, and also by the formation of ice-gorges near the mouths of many of the streams. it is probable, also, that the accumulation of ice across the northern part of the german ocean may have permanently flooded the streams entering that body of water; for it is by no means improbable that there was a land connection between england and france across the straits of dover until after the climax of the glacial period. in support of his theory, mr. tylor points to the fact "that the gravel in the valley of the somme at amiens is partly derived from _débris_ brought down by the river somme and by the two rivers the celle and the arve, and partly consists of material from the adjoining higher grounds washed in by land floods," and that the "quaternary gravels of the somme are not separated into two divisions by an escarpment of chalk parallel to the river," but "thin out gradually as they slope from the high land down to the somme." mr. tylor's reasoning seems especially cogent to one who stands on the ground where he can observe the size of the valley and the diminutive proportions of the present stream. even if we do not grant all that is claimed by mr. tylor, it is difficult to resist the main force of his argument, and to avoid the conclusion that the valley of the somme is largely the work of preglacial erosion, and has been, at any rate, only in slight degree deepened and enlarged during post-tertiary time. [footnote et: proceedings of the geological society, london, november , , pp. - : quarterly journal of the geological society, february , , pp. - .] summary. in briefly summarising our conclusions concerning the question of man's antiquity as affected by his known relations to the glacial period, it is important, first, to remark upon the changes of opinion which have taken place with respect to geological time within the past generation. under the sway of sir charles lyell's uniformitarian ideas, geologists felt themselves at liberty to regard geological time as practically unlimited, and did not hesitate to refer the origin of life upon the globe back to a period of , , years. in the first edition of his origin of species charles darwin estimated that the time required for the erosion of the wealden deposits in england was , , years, which he spoke of as "a mere trifle" of that at command for establishing his theory of the origin of species through natural selection. in his second edition, however, he confesses that his original statement concerning the length of geological time was rash; while in later editions he quietly omitted it. meanwhile astronomers and physicists have been gradually setting limits to geological time until they have now reached conclusions strikingly in contrast with those held by the mass of english geologists forty years ago. mr. george h. darwin, professor of mathematics at cambridge university, has from a series of intricate calculations shown that between fifty and one hundred million years ago the earth was revolving from six to eight times faster than now, and that the moon then almost touched the earth, and revolved about it once every three or four hours. from this proximity of the moon to the earth, it would result that if the oceans had been then in existence the tides would have been two hundred times as great as now, creating a wave six hundred feet in height, which would sweep around the world every four hours. such a condition of things would evidently be incompatible with geological life, and geology must limit itself to a period which is inside of , , years. sir william thomson and professor tait, of great britain, and professor newcomb, of the united states naval observatory, approaching the question from another point of view, seem to demonstrate that the radiation of heat from the sun is diminishing at a rate such that ten or twelve million years ago it must have been so hot upon the earth's surface as to vaporise all the water, and thus render impossible the beginning of geological life until later than that period. indeed, they seem to prove by rigorous mathematical calculations that the total amount of heat originally possessed by the nebula out of which the sun has been condensed would only be sufficient to keep up the present amount of radiation for , , years. the late dr. croll, feeling the force of these astronomical conclusions, thought it possible to add sufficiently to the sun's heat to extend its rule backwards approximately , , years by the supposition of a collision with it of another moving body of near its own size. professor young and others have thought that possibly the heat of the sun might have been kept up by the aid of the impact of asteroids and meteorites for a period of , , years. mr. wallace obtains similar figures by estimating the time required for the deposition of the stratified rocks open to examination upon the land surface of the globe. as a result of his estimates, it would appear that , , years is all the time required for the formation of the geological strata. from all this it is evident that geologists are much more restricted in their speculations involving time than they thought themselves to be a half-century ago. taking as our standard the medium results attained by wallace, we shall find it profitable to see how this time can be portioned out to the geological periods, that we may ascertain how much approximately can be left for the glacial epoch. on all hands it is agreed that the geological periods decrease in length as they approach the present time. according to dana's estimates,[eu] the "ratio for the palæozoic, mesozoic, and cenozoic periods would be : : "--that is, cenozoic time is but one sixteenth of the whole. this embraces the whole of the tertiary period, during which placental mammals have been in existence, together with the post-tertiary or glacial period, extending down to the present time; that is, the time since the beginning of the tertiary period and the existence of the higher animals is considerably less than two million years, even upon mr. wallace's basis of calculation. but if we should be compelled to accept the calculations of sir william thomson, professor tait, and professor newcomb, the cenozoic period would be reduced to considerably less than one million years. it is difficult to tell how much of cenozoic time is to be assigned to the glacial period, since there is, in fact, no sharply drawn line between the two periods. the climax of the glacial period represented a condition of things slowly attained by the changes of level which took place during the latter part of the tertiary epoch. [footnote eu: see revised edition of his geology, p. .] in order to estimate the degree of credibility with which we may at the outset regard the theory of mr. prestwich and others, that all the phenomena of the glacial period can be brought within the limits of thirty or forty thousand years, it is important to fix our minds upon the significance of the large numbers with which we are accustomed to multiply and divide geological quantities.[ev] [footnote ev: see croll's climate and time, chap. xx.] few people realise either the rapidity with which geological changes are now proceeding or the small amount of change which might produce a glacial period, and fewer still have an adequate conception of how long a period a million years is, and how much present geological agencies would accomplish in that time. at the present rate at which erosive agencies are now acting upon the alps, their dimensions would be reduced one half in a million years. at the present rate of the recession of the falls of st. anthony, the whole gorge from st. louis to minneapolis would have been produced in a million years. a river lowering its bed a foot in a thousand years would produce a cañon a thousand feet deep in a million years. if we suppose the glacial period to have been brought about by an elevation of land in northern america and northern europe, proceeding at the rate of three feet a century, which is that now taking place in some portions of scandinavia, this would amount to three thousand feet in one hundred thousand years, and that is probably all, and even more than all, which is needed. one hundred thousand years, therefore, or even less, might easily include both the slow coming on of the glacial period and its rapid close. prestwich estimates that the ice now floating away from greenland as icebergs is sufficient if accumulating on a land-surface to extend the borders of a continental glacier about four hundred and fifty feet a year, or one mile in twelve years, one hundred miles in twelve hundred years, and seven hundred miles (about the limit of glacial transportation in america) in less than ten thousand years. after making all reasonable allowances, therefore, prestwich's conclusion that twenty-five thousand years is ample time to allow to the reign of the ice of the glacial period cannot be regarded as by any means incredible or, on _a priori_ grounds, improbable. appendix. the tertiary man. by professor henry w. haynes. "it must not be imagined that it is in any way proved that the palæolithic man was the first human being that existed. we must be prepared to wait, however, for further and better authenticated discoveries before carrying his existence back in time further than the pleistocene or post-tertiary period."[ew] this was the position assumed more than twelve years ago by the eminent english geologist and archæologist, dr. john evans, and it was still maintained in his address before the anthropological section of the british association on september , . i believe that the study of all the evidence in favor of the existence of the tertiary man that has been brought forward down to the present time will leave the question in precisely the same state of uncertainty. [footnote ew: _a few words on tertiary man_, trans, of hertfordshire nat. hist. soc, vol. i, p. .] "in order to establish the existence of man at such a remote period the proofs must be convincing. it must be shown, first, that the objects found are of human workmanship; secondly, that they are really found as stated; and, thirdly, the age of the beds in which they are found must be clearly ascertained and determined."[ex] these tests i propose to apply to the evidence for the tertiary man recently brought forward in europe, and then to consider the significance of certain discoveries on the pacific coast of our own continent. [footnote ex: ibid., p. .] tertiary deposits in europe are alleged to have supplied three sorts of evidence of this fact: _first_, the bones of man himself; _second_, bones of animals showing incisions or fractures supposed to have been produced by human agency; _third_, chipped flints believed to exhibit marks of design in their production. a very complete survey of the question of the antiquity of man was published in by m. gabriel de mortillet, one of its most eminent investigators, under the title of le préhistorique. in that work he subjected to a most rigid examination all the evidence for tertiary man, coming under either of these three heads, that had been brought forward up to that date. the instances of the discovery of human bones in europe were two--at colle del vento, in savona, and castenedolo, near brescia, both in italy. at the former site, in a pliocene marine deposit abounding in fossil oysters and containing some _scattered_ bones of fossil mammals, a human skeleton was found _with the bones lying in their natural connection_. mortillet, however, and many others regard this as an instance of a subsequent interment rather than as proof that the man lived in pliocene times.[ey] at castenedolo, in a similar marine pliocene formation, on three different occasions human skeletons have been discovered, but in different strata. one investigator has accounted for these as the result of a shipwreck in the pliocene period. this bold hypothesis not only requires that man should have been sufficiently advanced at that very remote period to have navigated the sea, but it calls for two shipwrecks, at different times, at the same point. it has, however, since been abandoned by its author in favor of the presumption of subsequent interments, as in the previous instance.[ez] [footnote ey: this is also the opinion of hamy, _précis de paléontologie humaine_, p. . professor le conte, _elements of geology_ (third edition, ), p. , is wrong in attributing the opposite conclusion to hamy, on the evidence of "flint implements found in this locality."] [footnote ez: bullettino di paletnologia italiana, tome xv, p. (august , ).] animal bones showing cuts or breaks supposed to be the work of man have been found in seventeen different localities in europe. they can all, however, be accounted for as the result of natural movements or pressure of the soil acting in connection with sharp substances, like fractured flints, or else as having been made by the teeth of sharks, whose fossil remains are found in great abundance in the same formation. all the discoveries of flints supposed to show traces of intentional chipping are pronounced to be unsatisfactory, with the exception of those found in three localities--thenay (near tours) and puy-courny (near aurillac), in france, and otta, in the valley of the tagus, in portugal. as european archæologists at the present time are substantially in accord with mortillet in restricting the discussion to these three places, i will follow their example. but although mortillet believes that flints found at all these localities exhibit marks of intelligent action, he will not admit that they are the work of man. he attributes them to an intelligent ancestor of man, whom he calls by the name of anthropopithecus, or the precursor of man. of this creature he distinguishes three different species, named respectively after the discoverers of the flints in the three localities just mentioned. the precursor, however, has found up to this time only a very limited acceptance among men of science, although a few believe in him on purely theoretical grounds. the discussion generally turns upon the question whether these flints were chipped intentionally or are the result of natural causes; and also upon the determination of the geological age of the formations in which they are found. [illustration: fig. .--flint flakes collected by abbé bourgeois from miocene strata at thenay (after gaudry). natural size.] i visited thenay, the most celebrated of these three localities, in , and had the advantage of studying the question there under the guidance of the late abbé bourgeois, the discoverer of the flints, and one of the most prominent advocates of the tertiary man. this was the year before he died, and he showed me at the time his complete collection, and gave me several of the objects he had discovered. geologists are agreed in assigning the deposits in which they occur to the lower miocene or middle tertiary period, which restricts the discussion to the character of the flints themselves. the accompanying woodcut[fa] gives some indication of their appearance, although it is misleading, because the long figure resembling a flint knife is intended to represent a solid nucleus. none of these objects, however, ought to be called "flints flakes," as very few, if any, flakes showing the "bulb of percussion," always seen upon them, have been discovered in the tertiary deposits at thenay,[fb] although i have found them there myself _upon the surface_. the three other figures would be classed by archæologists as "piercers," as bourgeois has himself designated them, and are also solid objects. many of the thenay flints exhibit a "crackled" appearance, due to the action of heat. on this account mortillet maintains that they were splintered by fire, and not formed by percussion, the usual method by which flint implements were fabricated in the stone age. the thenay objects are all of very small dimensions, and are so absolutely unlike the large, rudely-chipped axes of the chellean type, found in so many different parts of the world, and generally accepted as the implement used by palæolithic man, that the question naturally suggests itself, what could have been the purpose for which these little implements were employed? no better answer has been suggested than the ludicrous one that they were used by the hairy anthropopithecus to rid himself of the vermin with which he was infested. [footnote fa: from le conte, _op. cit._, p. . the figures are copied from gaudry, who borrowed them from the article by bourgeois, _congrès internat. de bruxelles_, , p. , pl. ii; and from his _la question de l'homme tertiare_. revue des questions scientifiques, , p. .] [footnote fb: le préhistorique, p. .] but, leaving aside the question of their purpose, let us consider the evidence presented by the flints themselves. do they exhibit the unmistakable traces of intentional chipping produced by a series of slight blows or thrusts, delivered in regular succession and in the same direction, with the result of forming a distinctly marked edge? and does the appearance of the action of fire upon their surface imply the intervention of intelligence? to both questions m. adrien arcelin, the well-known geologist of mâcon, has given very sufficient replies in the negative. he has discovered numerous objects of precisely similar appearance in eocene deposits in the neighborhood of mâcon.[fc] but, instead of pushing man back on this account so much further into the past, he accounts for the marks of chipping to be seen on many of these objects as the result of the accidental shocks of one stone against another in the countless overturnings and movements to which the strata have been subjected during the long ages of geological time. he gives photographs of some of these objects, which are to me entirely convincing, and describes how he has surprised nature in the very act of fabricating them in an abandoned quarry worked in an eocene deposit. he thinks the "crackled" surfaces can be readily explained as the result of atmospheric action, or of hot springs charged with silex. numerous examples of similar changes in the surface of flint, that have been noticed by himself and others in different localities, are instanced. even if some have been caused by fire, this does not necessarily imply the intervention of man to have produced it. similar discoveries have also been made by m. d'ault de mesnil, at thenay, in eocene deposits,[fd] and by m. paul cabanne, in the gironde.[fe] my own opinion, based upon the experience of many years spent in the study of flints broken naturally as well as artificially, and upon a careful examination of bourgeois's collections, is that the so-called thenay flints are the result of natural causes. [footnote fc: matériaux pour l'histoire prim, et nat. de l'homme, tome xix, p. .] [footnote fd: matériaux, ibid., p. .] [footnote fe: id., tome xxii, p. .] the second locality where flints alleged to display marks of human action have been found is the vicinity of aurillac, in the auvergne, especially on the flanks of a hill called puy-courny. they occur in a conglomerate of the upper miocene period, and are consequently much later than the thenay flints. in this conglomerate, in , m. tardy discovered a worked flint flake which has every appearance of being artificial.[ff] mortillet, however, says that it was found in the upper surface of the deposit, where there may easily have been a mingling with the quaternary formation; and it certainly resembles worked flakes, which are not uncommon in the quaternary. the geological determination of the find may consequently be regarded as uncertain. [footnote ff: see matériaux, tome vi, p. . s. reinach, however, _description raison. du musée de saint-germain-en-laye_, i, p. , n. , calls it "gravure inexacte."] the flints discovered at puy-courny by m. barnes are of small dimensions, and have all been produced by percussion. many of them are said to bear some resemblance to pointed flakes of artificial origin, and one has been figured, probably selected for its excellence.[fg] it is by no means convincing to me, and i am not at all surprised that so many archæologists question the artificial character of these objects, which exhibit a great variety of forms. upon this point rames does not profess to be qualified to pronounce judgment, limiting himself solely to the geological questions. he argues, however, that the fact that all the objects supposed to be artificial are made of the best qualities of flint, of which implements are ordinarily made, although fragments of inferior quality are abundant in the same formation, implies the intervention of man's judgment in making the selection. but m. boule shows that this is merely the result of the erosion of an ancient river, which operated only upon the upper beds, in which alone the better qualities of flint are to be found; and rames has accepted this explanation.[fh] the flints of puy-courny seem to fall within the same category as those of thenay. they are the product of denudation, have travelled long distances, and have been subjected to the action of powerful agents. these causes are sufficient to account for the shocks of which they show the traces, and to explain the production of splinters arising therefrom. [footnote fg: matériaux, tome xviii, p. .] [footnote fh: revue d'anthropologie (third series), tome iv, p. .] the last locality in which flints claimed to have been manufactured by the tertiary man are supposed to have been discovered is the so-called desert of otta, in the valley of the tagus, not far from lisbon. the formation there is a lacustrine deposit of great thickness, belonging to the upper miocene, and abounding in flint. here, during the course of twenty years, m. ribeiro discovered, but mostly upon the surface, a large number of flakes of flint and quartzite. after much debate in regard to them, ninety-five of them were finally sent by him to paris, in , and placed in the archæological department of the great exposition. there they were to be submitted to the judgment of the assembled prehistoric archæologists of all nationalities, many of whom, including the writer, availed themselves of the opportunity of carefully studying them. the judgment of mortillet is that twenty-two specimens exhibited unmistakable traces of intentional chipping, in which opinion i entirely concur. only nine, however, were represented as coming from the miocene, some of which showed on their surface an incrustation of grit, which was claimed as proof of their origin. but the opinion was freely expressed that, even if they really came from the miocene deposits, they might have penetrated into them from the surface, through cracks, and thus have become so incrusted. it was accordingly resolved to hold the next international congress of prehistoric archæologists at lisbon, in , mainly for the purpose of settling this question, if possible, by an investigation conducted upon the spot. in the course of a visit made at that time to otta, several artificial specimens were found on the surface by different searchers, but professor bellucci, of perugia, was fortunate enough to discover a flint flake _in situ_, still so closely imbedded in the deposit that it required to be detached by a hammer. there is no question that this object was actually found in a miocene deposit, but unfortunately it belongs to the doubtful category of external flakes, which, although they exhibit the "bulb of percussion," have no other sure indication that they are the work of man.[fi] as such bulbs can be produced by natural causes, some stronger proof than this of the existence of tertiary man is demanded. [footnote fi: it has been figured by bellucci, _archivio per l'anthropologia e la etnologia di firenze_, tome xi, p. , tav. iv, fig. . to me it possesses no value as evidence.] these are all the localities in europe claimed by mortillet to have furnished such evidence, but he thinks a strong confirmation of it is afforded by certain discoveries made in the auriferous gravels of california. i will not occupy space here in repeating arguments i have brought forward elsewhere to show the utter insufficiency of this evidence to prove the existence of man on the pacific coast of our continent during the pliocene period,[fj] they may all be summed up in the words of le conte: "the doubts in regard to this extreme antiquity of man are of three kinds, viz.: . doubts as to the pliocene age of the gravels--they may be early quaternary. . doubts as to the authenticity of the finds--no scientist having seen any of them in situ. . doubts as to the undisturbed conditions of the gravels, for auriferous gravels are especially liable to disturbance. the character of the implements said to have been found gives peculiar emphasis to this last doubt, _for they are not paleolithic_, but neolithic."[fk] the question has been raised whether this archæological objection is applicable to the stone mortars, numerous examples of which have been found in the gravels, some of them quite recently.[fl] if the evidence brought forward by professor whitney and others were limited to these mortars, it might very well be claimed that they are neither palæolithic nor neolithic; that the smoothness of their surface is owing to their having been hollowed out of pebbles that have been polished and worn by natural forces. but professor whitney has cited numberless instances of "spear-heads," "arrow-heads," "discoidal stones," "stone beads," and "a hatchet" that have been found under precisely similar conditions as the mortars. so mr. becker has recently produced an affidavit of a certain mr. neale that in a tunnel run into the gravel in "between two hundred and three hundred feet beyond the edge of the solid lava, he saw several spear-heads nearly one foot in length."[fm] now it cannot be questioned that such objects as these clearly belong to the neolithic period, which does not imply that all the objects used at that time were polished, but that together with chipped implements "polished stone implements were also used."[fn] no archæologist will believe that, while palæolithic man has not yet been discovered in the tertiary deposits of western europe, the works of neolithic man have been found in similar deposits in western america. peculiar difficulties seem to surround the evidence brought forward in support of such an assumption. we are told by professor whitney that a stone mortar was "found standing upright, and the pestle was in it, in its proper place, just as it had been left by the owner." he fails, however, to explain how this was brought about in a gravel deposit supposed to have been laid down by great floods of water. so, when mr. neale swears that he saw fifteen years ago in the same gravels spear-heads a great deal larger than those known to archæologists, may we not ask whether reliance can be placed on the memory of witnesses who testify to impossibilities to justify conclusions that rest upon such testimony? i think we shall have to wait for further and better evidence than this before we are called upon to admit that the existence of the tertiary man upon our pacific coast has been established. [footnote fj: _the prehistoric archæology of north america_, narrative and critical history of america, vol. i, pp. - .] [footnote fk: le conte, _op. cit._, p. .] [footnote fl: professor george frederick wright, _prehistoric man on the pacific coast_, atlantic monthly, april, , p. ; _table mountain archæology_, nation, may , , p. .] [footnote fm: _antiquities from under tuolome table mountain in california_, bulletin of the geological society of america, vol. ii, p. .] [footnote fn: le conte, _op. cit._, p. .] index. aar glacier, , , . abbeville, france, , . abbott, c. c, cited, , . adams, charles francis, cited, . adhémar, cited, , . africa, ancient glaciers of, . agassiz, louis, cited, , , , , . ailsa crag, , . akron. ohio, , . alaska, , , _et seq._, , , ; climate of, , . aletsch glacier, , , . alleghany valley, , ; terraces in, . alpine glaciers, existing, - , _et seq._; size and number of, ; depth of, ; velocity of, _et seq._; ancient, - , - ; advance and retreat of, . alps, , - , _et seq._, _et seq._, , _et seq._, ; age of, . altaville, cal, . amazon valley, temperature of, . amherst, ohio, glacial marks near, . amiens, france, implements from, , _et seq._; terraces at, . andes, , ; age of, . andover, mass., _et seq._, . andrews, cited, , , , . animals, extinct, associated with man in eastern america, ; in france, ; in england, _et seq._; in wales, ; in belgium, _et seq._; summary concerning, - . animals, relics of, in loess, . antarctic continent, existing glaciers of, , _et seq._ arcy, belgium, grotto at, . arenig mawr, wales, , , . argillite implement, face and side view of, , . arnhem, holland, moraine at, . asia, existing glaciers in, _et seq._; ancient glaciers of, . assiniboine river, . astronomical theories of the glacial period, _et seq._ atlantic ocean, . aurillac, supposed flint-chips near, , . australia, ancient glaciers of, , . austria, existing glaciers of, . auvergne, . babbitt, miss f. e., cited, , , . bakewell on age of niagara gorge, . baldwin, c. c, . baldwin, p., . ball, cited, , . baltic sea, . barnsley, england, . bates, cited, . bear, , , . bear, grizzly, , . beaver, . beaver creek, pa., , , . becker, cited, , , . bedford, england, . beech flats, ohio, terrace at, . belgium, human relics in glacial terraces in, ; caverns of, . bell, cited, , ; on unity of the glacial period, . bellevue, pa., glacial terrace on the ohio at, . bellucci, cited, . ben nevis, . bernese oberland, , , , . big stone lake, , . birmingham. england, . bishop, cited. . bison, , , , , . black forest, the, . black river, ohio, . black sea, . blanc, mont, , - , , . blandford, cited, . boone county, ky., glacial deposits in, . boston, scratched stone from till of, ; drumlins in the vicinity of, . boston society of natural history, . boulder-clay. (see till.) boulders, disintegrated, , . boulders, distribution of, in new-england, , , , _et seq._; in switzerland, _et seq._, . boulders, transportation of, in pennsylvania, , , ; in new hampshire, , ; in kentucky, , ; in ohio, , ; in rhode island, ; in massachusetts, _et seq._; in connecticut, , ; in new jersey, ; in illinois, . bourgeois, abbé, cited, . bridgenorth, england, . bridlington, england, , . bristol channel, , . british columbia, , , _et seq._, , . british isles, ancient glaciers of, - ; preglacial level of land in, - ; preglacial climate in , ; great glacial centres-- wales, ; ireland, ; galloway, ; lake district, ; pennine chain, ; confluent glaciers-- irish sea glacier, - ; solway glacier, - ; east anglian glacier, ; isle of man, - ; the so-called great submergence, - ; dispersion of erratics of shap granite, , ; drainage of, ; caverns of, ; climate of, . brixham cave, _et seq._ bromsgrove, england, . brooklyn, n. y., , . brown, on glaciers of greenland, , . brown's valley, . bruce, skull of, . buried forests in america, _et seq._ buried outlets and channels, - ; of lake erie, , ; of lake huron, ; of lake ontario, ; of lake superior, ; of lake michigan, ; in southwestern ohio, ; near cincinnati, ; near louisville, ky., ; in the tuscarawas valley, ; in the valley of the beaver, ; of oil creek, ; in the valley of the alleghany, ; of chautauqua lake, ; near minneapolis, . burton, england, . busk, cited, . buttermere, england, , . cache valley, utah, . cae gwyn cave, , _et seq._, . caithness, scotland, . calaveras skull, , . california, , , , , , , . cambridgeshire, england, . canada, , . canstadt, man of, . canton, ohio, . cape st. roque, . caribbean sea, . caribou, . carll, cited, , . carpathian mountains, , . carpenter, f. r., cited, , . cascade range, . caspian sea, . cattaraugus creek, n. y., . caucasus mountains, ; age of, . cave-bear, - , , ; hyena, , , ; lion, - , . caverns, british, - ; on the continent, - . cefn cave, , . cenis, mont, . centres of glacial dispersion, _et seq._, _et seq._, ; in america, , ; in europe, _et seq._; in the british isles, _et seq._ cevennes, . chamberlin, t. c, terminal moraine of second glacial epoch, , _et seq._; on driftless area, , ; cited, , , , ; on cincinnati ice-dam, . chamois, , . chamouni, . charpentier, , . chasseron, , . chautauqua lake, buried outlet of, . chenango river, . cheshire, england, , , , . cheyenne river, . chicago, ill., . chimpanzee, skull of, . chur, . cincinnati, buried channels near, _et seq._; glacial dam at, _et seq._; terraces at, . clarksburg, w. va., . claymont, del., _et seq._; view of implement found near, . claypole, cited, , , . climate of glacial period, . clwyd, vale of, _et seq._. _et seq._ clyde, the, . collett, cited, . colorado, , . columbia deposit, , _et seq._ columbiana county, ohio, . comstock, cited, . conewango creek, ; ancient depth of, . connecticut, , , , . conyers, cited, . cook on subsidence in new jersey, . cope, cited, . cordilleran glacier, _et seq._ corswall, england, . cows, . cresson, cited, , _et seq._ crevasses. (see fissures.) croll, cited, , _et seq._, , . cro-magnon, rock shelter of, . cromer, england, . crosby, on composition of till, _et seq._ cross fell escarpment, , . culoz, . cumberland, england, , , , . gumming, quoted, . gushing, h., cuyahoga river, , ; buried channel of, . dana, professor j. d., on depth of ice, ; on driftless area, ; cited, , . danube, ancient glaciers of the, , , . darent, valley of, . darrtown, ohio, . darwin, charles, cited, , , , , . darwin, george g., cited, . darwin, mrs. m. j., mortar owned by, . date of glacial period, chapter on, - . davidson glacier, . davis on drumlins, . dawkins, cited, , , , . dawson, g. m., cited, ; on ice-movements, ; on oscillation of land-level, , . dawson, sir william, on the fiord of the saguenay, ; cited, . dee, the river, . deeley, quoted, . delaware river, , _et seq._, , ; section across the, . delta terrace at trenton, n. j., _et seq._; at beaver, pa., . de ranee, cited, . derbyshire, england, . desor on age of niagara gorge, . diore, glaciers of the, . disintegration, amount of, near glacial margin, , . diss, england, . dnieper, the, , . don, the, , . dora baltea, . dover, n. h., section of kame near, . dover, straits of, . drave, glaciers in the, . drainage systems in the glacial period, , , , , ; chapter on, - . drayson, cited, . driftless area in the mississippi valley, , . drumlins, description of, _et seq._; view of, ; occurrence of, in massachusetts, ; in new hampshire, ; in connecticut, ; in new york, , ; in the british isles, , , . dunbar, scotland, . dupont, cited, . du quoin, ill., , . d'urville, . düsseldorf, . eagle, wis., view of kettle-moraine near, . east anglian glacier, - . eccentricity of the earth's orbit, . eden valley, . eggischorn, , . eguisheim, skull found at, . elephant, , , , , . elevation, preglacial, , , ; the cause of the glacial period, , - ; about the great lakes, ; in the latitude of new york, . elyria, ohio, . engis skull, view of, . england. (see british isles.) enville, england, . erosion, preglacial, _et seq._ erosion in river valleys, , , . erzgebirge, , . europe, existing glaciers in, , _et seq._, _et seq._; ancient glaciers of, - ; former elevation of, ; ice-dams in, . evans, cited, , , , . falconer, cited, . falls of st anthony, . faudel, cited, . fiesch, switzerland, , . filey brigs;, eng., . finchley, eng., , . finger lakes, . finsteraarhorn, . fiords, _et seq._; of greenland, . fissures in glacial ice, , , . flamborough, , , , . florida, . flower, cited . forbes, , , , , . forel, m., cited, . fort snelling, mississippi gorge at, , _et seq._ fort wayne, incl., , . foshay, cited, . fox, , , . fraipont, cited, _et seq._ france, existing glaciers of, ; ancient glaciers of, ; glacial gravels of, _et seq._ frankley hill, england, . franklin, pa., , . franz-josef land, . frederickshaab glacier, , . frere, cited, . frickthal, . frondeg, wales, , . gabb, cited, . galloway, ancient glaciers of, , , , , , , . garda, lake, moraine in front of, . garonne, the, , . gaudry, cited, . geikie, archibald, cited, , . geikie, james, on kames, ; on loess, , ; cited, _et seq._, , . genesee river, . geological time, _et seq._ georgian bay, . german ocean, . germantown, ohio, , . germany, north, moraine in, , ; glacial lakes in, ; quaternary animals in, . gietroz glacier, . gilbert, cited, _et seq._, _et seq._; on age of niagara gorge, . glacial dispersion. (see centres of glacial dispersion.) glacial boundary in new england, ; in new jersey, ; in pennsylvania, _et seq._; in new york, ; in ohio, , , ; in kentucky, ; in indiana, ; in illinois, , ; in kansas, nebraska, missouri, montana, south dakota, ; in minnesota, ; in british isles, , , , , , ; in holland, ; in germany, , ; in russia, , . glacial erosion, , , . glacial ice, depth of, in pennsylvania, _et seq._; in connecticut, ; in new york. ; in greenland, ; in the alps, , , , ; in germany, ; in norway, ; amount of, . glacial lakes in germany, . glacial motion, limit of, ; chapter on, - ; plastic theory of, . glacial outlets of the great lakes, - . glacial periods, cause of, ; chapter on, - ; date of, chapter on, - . glacial periods, supposed succession of, _et seq._, , - , ; criticisms of the theory, _et seq._ glacial striæ. (see rock-scoring.) glacial terraces, - ; in pennsylvania, _et seq._, , , , ; in new york, ; at beech flats, ohio, ; at granville, ohio, ; on the minnesota river, ; around great salt lake, _et seq._; on delaware river, _et seq._; in europe, - ; in ohio, _et seq._; human relics in, - ; on delaware river, ; of the mississippi river, ; in france, _et seq._, ; in england, _et seq._; in belgium, ; in spain, ; in portugal, ; in italy, ; in greece, . glacial theory, crucial tests of, , , , _et seq._ glaciation, signs of past, chapter on, _et seq._ glacier bay, ; map of, . glacier, denned, ; formation of, ; characterised by veins and fissures, ; advance and retreat of, ; velocity of, in the alps, _et seq._; in greenland, , - ; in alaska, . glaciers, ancient, in north america, - ; in central and northern europe, - , - ; in the british isles, - ; in northern europe, - ; in australia, , ; in asia, , ; in africa. , . glaciers, existing, in the alps, _et seq._, _et seq._; in scandinavia, ; in spitzbergen, nova zembla, and franz-josef land, ; in iceland, ; in asia, _et seq._; in oceanica, ; in south america, ; in antarctic continent, _et seq._; in north america, _et seq._; in greenland, _et seq._, , , . glen roy, parallel roads of, . glutton, . goat, . goffstown, n. h., . grafton, w. va., . grand haven, mich., . granville, ohio, terrace at, , . grape creek, col., view of moraines of, . great bend, pa., depth of river-channel at, . great lakes, depth of, ; formation of, _et seq._; glacial outlets of, - ; elevation about, . great salt lake, utah, _et seq._, . greece, human relics in glacial terraces of, . greenland, existing glaciers of, , _et seq._, , , ; map of, ; climate of, . gross glockner, , . ground ice, . gulf of mexico, , . gulf stream, , , , _et seq._ guyot, , , . haas, . hall, on the age of niagara, . hare, . harrison, quoted, . harte, bret, cited, . hartz mountains, , . hayes, . haynes on tertiary man, - . heald moor, england, . hebrides, the, . heim, . helland, , - . hennepin, cited, . heme bay, england, . herschel, cited, . hertfordshire, england, . hicks, dr. ii., cited, . hicks, l. e., cited, . himalayas, , , , ; age of, . hingham, mass., section of kame near, . hippopotamus, , , , , , , , . hitchcock, c. ii., discovery of boulders on mount washington, ; on drumlins, ; cited, , . hitchcock, e., on kames, . holland, terminal moraine in, . holderness, . hooker, cited, . horse, , , - , , , , , . horseheads, n. y., . horseshoe fall, _et seq._ hottentot skull, . hoxney, england, . hudson river, preglacial channel of, _et seq._ hugi, , . hungary, quaternary animals in, . huxley, cited, , . hyena, , , , , . ibex, . icebergs, , ; formation of, . ice, characteristics of, , _et seq._, _et seq._; transporting power of moving, . ice-dams, - ; in the alps, ; in the himalayas, ; in greenland, ; in alaska, ; at cincinnati, _et seq._; across the mohawk, , , , ; in the red river of the north, ; in europe, . iceland, existing glaciers of, , . ice-pillars, , . ice-sheet, retreat of, _et seq._ idaho, ; lava-beds of, . illicilliwaet glacier, . illinois, - , , , , _et seq._ indiana, , , , , . indian ridge, . iowa, , . ireland, ancient glaciers of, . irish elk, , , . irish sea glacier, , - , , . irthing, valley of the, . isère, glaciers of the, . isle of man, - . isle of wight, . italy, existing glaciers of, ; ancient glaciers of, ; human relics in glacial terraces of, ; supposed tertiary man in, . ivrea, . jackson, cited, . jackson's lake, . jakobshavn glacier, velocity of, , ; depth of, ; ice-dams of, . james, cited, . james river, dak., . james river, va., . jamieson, cited, . jensen, . judge's cave, . jura mountains, ancient glaciers of, - , . kames, formation of, , , ; of muir glacier, , ; in massachusetts, _et seq._; in new hampshire, ; map of, in maine, ; in pennsylvania, . kanawha river, . kane, - . kansas, . kelly's island, view of grooves on, , . kendall, chapter by. - ; cited, . kent, england, . kent's hole, _et seq._, _et seq._ kentucky, , , , ; view of boulder in, . kentucky river, . kettle-holes, formation of, , ; of muir glacier, , ; in new england, _et seq._, , ; in pennsylvania, ; sedimentation of, , _et seq._ kettle-moraine in wisconsin, . king, , ; implement discovered by, . knox county, ohio, . kurtz, nam pa image discovered by, . lake agassiz, , , ; continuance of, _et seq._ lake bonneville, _et seq._, , _et seq._ lake constance, , . lake erie, origin of, _et seq._; ridges around, ; preglacial outlet of, , . lake geneva during the glacial period, , . lake huron, preglacial outlet of, ; ridges around, . lake itasca, . lake lahontan, , . lake michigan, age of, _et seq._ lake nipissing, . lake ontario, origin of, _et seq._ lake traverse, , . lake district, england, the, . lake dwellings in switzerland, . lake ridges, _et seq._ lakes, sedimentation of, , _et seq._ lamplugh, glacial observations of, , . lancashire, , , . lancaster, ohio, . lang, cited, . lark, england, valley of the, . lateral moraines, . laurentide glacier, _et seq._, , . lava on the pacific coast of north america, , , , , . lawrence, mass., . lawrenceburg, ind., , . le conte, cited, , _et seq._, , . leicestershire, england, . lehigh river, . lemming, . lenticular hills, . leopard, . lesley, cited, . lesse, belgium, valley of the, . leverett, cited, , . lewis, on transported boulders, , ; work of, in pennsylvania, , ; in great britain, ; cited, _et seq._, . lickey hills, . licking river, . liége, belgium, . lincolnshire, england, . lindenkohl on old channel of the hudson, _et seq._ lion, , . little beaver creek, , . little falls, minn., , , , . little falls, n. y., buried channel near, . livingston, mont., . llangollen, vale of, . loess in the mississippi valley, , , ; in europe, _et seq._ lohest, cited, _et seq._ lombardy, . london, , , ; glacial terrace in, . long island, , . louisville, ky., buried channel near, . loveland, ohio, , . lubbock, cited, . lucerne, . lyell, on richmond train of boulders, ; cited, , , , , , , , ; on the age of niagara, . lyons, . maack, cited, . macclesfield, england, . macenery, cited, . machairodus, , . mackintosh, quoted, , , . mâcon, france, . mctarnahan, mortar discovered, by . madison boulder, . madisonville, ohio, , , . magdalena bay, . mahoning river, . maine, ; re-elevation of, . malaspina glacier, map of, . mammoth, , , , , - , , , - , , , . man, relics of, in the glacial period, chapter on, - ; in glacial terraces of the united states, - ; of europe, - ; in cave deposits of british isles, , - ; of the continent, - ; under lava-beds of the pacific coast of north america, - ; extinct animals associated with, - . manitoba, . mankato, minn., . marcilly, skull at, . marietta, ohio, . marmot, , . marsh creek valley, utah, . martigny, ancient glaciers near, , , , . massachusetts, _et seq._, , _et seq._, , , . mastodon, , , , . mattmark see, . maumee river, . mcgee, cited, , _et seq._ medial moraines, formation of, ; of muir glacier, ; in ohio, . medlicott, cited, . medora, ind., , , . menai straits, . mentone, skeleton of, . mer de glace, , . merjelen see, , . mersey, the, . meteorites, . metz, cited, . meuse, valley of, _et seq._ miami, the great, , . miami, the little, , . millersburg, ohio, . mills, cited, . minneapolis, ; buried outlet near, ; recession of falls at, , _et seq._, . minnehaha, falls of, . minnesota, , , _et seq._; lakes of, . minnesota river, a glacial outlet, , , , . miocene epoch, animals of the, . mississippi river, gorge of, at fort snelling, , ; terraces on, ; erosion by, ; glacial drainage of, , . missouri coteau, , , . missouri, , , . moel tryfaen, , _et seq._, , . mohawk river, glacial drainage of, , , ; ice-dam across, , , . mohegan bock, ; view of, . monongahela river, _et seq._ montaigle, valley of the, . montana, . montreal, re-elevation of, . moose, . moraines, formation of, ; in wisconsin, - ; in italy, , ; between speeton and flamborough, ; in germany, . morecambe bay, , . morgantown, w. va., . morlot, cited, . mortillet, cited, , , . morvan, the, . moulins, formation of, . mount shasta, . mount washington, . mueller glacier, . muir glacier, _et seq._. , , ; view of front of, . muir, john, . muskingum river, , . musk ox, , . musk sheep, , , . nampa image, _et seq._ nansen, , . naulette, jaw found at, , . neale, implements discovered by, , . neanderthal skull, _et seq._ nebraska, . nelson river, . neufchâtel, . nevada, ; lakes of, . névé-field defined, . newark, ohio, . newberry on the preglacial drainage of the hudson, _et seq._; on the formation of the great lakes, _et seq._; cited, . newburg, n. y., . new comerstown, implement from, , , _et seq._, . new england, , , , ; ancient glaciers in, - . new hampshire, , , , . new harmony, ind., . new jersey, . new lisbon, ohio, . new york, , , , , _et seq._ new york bay, , , . new zealand, , , , . niagara gorge, age of, _et seq._; section of strata along the, . nile river, . nordenskiöld, , . norfolk, england, . north america, existing glaciers in, _et seq._ north sea, . norway, climate of, . nottingham, england, . nova zembla, . oberlin, ohio, , . oceanica, existing glaciers of, , . ohio river, glacial terrace, , . ohio, , , , , , , , - , , , _et seq._, , . oil creek, , . olmo, skull at, . oregon, , . orme's head, little, . orton, cited, , . oscillations of land-level in america, _et seq._ oswestry. england, . ottawa river, . otter, . ouse, valley of the, . ox, , . pacific coast of america, . pacific ocean, , . panama, isthmus of, , , , . parsimony, law of, . pasterzen glacier, . patagonia, . patton, . payer, , . peat-beds, , ; in ohio, ; in minnesota, ; in valley of the somme, _et seq._ pembina river, . pengelly, cited, , . pennine chain, glaciation of, , , , , , . pennsylvania, , , _et seq._, , . perry county, ohio, . perthes, boucher de, _et seq._ philadelphia academy of sciences, . philadelphia, red gravel of, _et seq._ phillips, cited, . picardy, glacial gravels of, . pittsburg, pa., submergence of, , , . plum creek, ohio, . po, valley of the, ; erosion by, . pocatello, idaho, , . pocono mountain, . poland, . polynesian skull, . pomp's pond, section of kettle-hole near, . portageville, n. y., . port neuf river, idaho, . portsmouth, ohio, . portugal, human relics in glacial terraces of, ; supposed tertiary man in, , _et seq._ post-glacial erosion, _et seq._; in ohio, , ; in illinois, _et seq._ potomac river, _et seq._ pot-holes in lucerne, . pouchet, cited, . precession of equinoxes, . preglacial climate in england, , . preglacial levels in england, - . prestwich, cited, , , _et seq._, ; on date of glacial period, , , , . provo shore-line, . putnam, cited, . puy-courny, france, supposed tertiary man at, , , . pyramid lake, . pyrenees, glaciers of the, , ; quaternary animals of, , ; age of, . quaternary animals of california, , ; in germany, ; in hungary, . quatrefages, cited, . queenston, canada, _et seq._ rabbit, . raccoon creek, ; view of glacial terrace near, . rames, cited, , . ramsay, cited, . rappahannock river, . rawhide gulch, cal., . recession, rate of, of falls of niagara, _et seq._; of falls of st. anthony, _et seq._, ; of black river, , . red deer, . red river of the north, , , ; ice-dam in, . regillout, . reid, clement, quoted, . reid, h. f., , . reindeer, , , , , , , , , , . rhine, ancient glaciers of the, , . rhinoceros, , , , , , , , , , , ; woolly, , , , , . rhode island, . rhône, ancient glaciers of, - , , , , ; map of, . richmond, mass., train of boulders in, , . rink, dr., . roanoke river, . rocky mountains, , ; age of the, . rock-scorings, cause of, _et seq._; in new england, ; on islands of lake erie, , ; in pennsylvania, ; in ohio, , ; in indiana, ; in illinois, ; in missouri, . roman remains, . rome, n. y., . rosa, mount, , , . ross, sir j. c, , , . royston, england, . runaway pond, . russell, i. c, exploration of mount st. elias by, , ; cited, , _et seq._ russia, glacial boundary in, , ; glacial drainage of, . saguenay, fiord of the, . salamanca, n. y., buried channels near, . salisbury, cited, , . salt lake city, . sandusky, ohio, section of the lake ridges near, . sandusky river, . sanford, cited, . saskatchewan river, . saxony, . scandinavia, existing glaciers of, , ; ancient glaciers of, , , , - ; re-elevation of, . scioto river, . scotland. (see british isles.) seattle, section of till in, . second glacial period, _et seq._ section, ideal, across river bed in drift region, . sedimentation of lakes, . seine, terraces of the, , , . seracs, , . settle, england, . severn, the, - , . shaler, , . shap granite, , , . ship rock, . shone, cited, . shoshone falls, . shrewsbury, england, . shropshire, england, , . siberia, ; quaternary animals in, , , , ; climate of, , . sierra nevada mountains, , , , , , , . skertchly, quoted, . skipton, , . skull, comparative study of, . slickenside, . smock on depth of glacial ice, . snake river valley, _et seq._, . snowdon, , . snowy vole, . soleure, . solferino, . solway glacier, , , . somme, terraces of the, , _et seq._, , , , _et seq._ sonora, cal., _et seq._ south america, existing glaciers of, ; ancient glaciers in, . southampton, england, . south dakota, , . spain, ancient glaciers of, ; human relics in glacial terraces of, ; quaternary animals of, . speeton, , , . spencer, cited, . spencer, n. y., . spitsbergen, . spy, man of, , . st. acheul, . stag, . stainmoor, england, , , . stalagmite, rate of accumulation of, _et seq._ stanislaus river, cal., . st. anthony, falls of, _et seq._, . steamburg, n. y., buried channel at, . st. elias, _et seq._, . st. lawrence river, glacial drainage of, , . st. louis, mo., , . st. paul, minn., . stone on kames in maine, . straits of dover, . straits of gibraltar, . striæ, direction of, in new hampshire, ; in lake erie, ; presence of, in pennsylvania, , ; in ohio, indiana, illinois, and missouri, ; in stuttgart, . subglacial streams, , , . submerged channels on the coasts of america, - . submergence theory, - , . subsidence of the isthmus of panama, , ; in mississippi valley, , , , ; on east coast of north america, _et seq._; about the great lakes, , ; in great britain, - . susquehanna river, glacial drainage of, , , . svartisen glacier, . svenonius, dr., . sweden, . switzerland, existing glaciers of, - ; ancient glaciers of, - ; lake-dwellings in, . table mountain, cal., _et seq._, . table of changes during the glacial epochs, , . tagus, valley of the, , _et seq._ tait, cited, . tardy, cited, . tasman glacier, . teesdale, england, , . terminal moraines, formation of, ; in pennsylvania, , , _et seq._; on the southern coast of new england, _et seq._; in ohio, ; in puget sound, ; in tyghee pass, ; in italy, . terminal moraines of the second glacial epoch, , , , . terraces. (see glacial terraces.) tertiary animals, . tertiary man, - . tertiary period, climate of, , , , , . teton mountains, . texas, pleistocene animals of, . thames, england, , , . thenay, france, supposed tertiary man in, , ; view of flint-flakes collected at, . thompson, . thomson, cited, . till, description of, ; composition of, in massachusetts, _et seq._; section of, in ohio, ; depth of, in germany, scandinavia, and russia, . tinière river, . titusville, pa., . todd, on forest beds and old soils, _et seq._; cited, . torquay, england, . trade-winds of the atlantic, , . tremeirchon, wales, . trenton, n. j., , , _et seq._, , ; view of implement found at, . trenton gravel, section of the, . trent, valley of the, , . trimmer, quoted, . trimingham, england, . trogen, switzerland, . trons, switzerland, . tuolumne county, cal., , . turin, . tuscarawas valley, , , , ; buried channel in, . tylor, cited, _et seq._ tyndall, - , . tynemouth, england, , . tyrol, , , . tyrrell, cited, . ulm, . upham, on drumlins, ; on two ice-movements, ; cited, , _et seq._, , , _et seq._, , ; on the columbia gravel, ; on date of the glacial period, . ural mountains, , . utah, ; lakes of, . utica, n. y., . utrecht, moraine near, . valais, the, . vegetable remains in glacial deposits, , ; in ohio, , ; in indiana, ; in minnesota, , ; in iowa, ; in british america, . veins in glacial ice, . vermont, runaway pond in, . vernagt glacier, . vessel rock, view of, . vezère, valley of, . victoria cave, england, , . virginia city, . vivian, cited, . volga, the, . vosges mountains, . wabash river, , , . wahsatch mountains, . wales, ancient glaciers of, , _et seq._; caverns of, . wallace, cited, , , . walrus, , . warren, pa., buried channel near, . warren river, . washington, , , . washington, d. c., gravel deposit of, . water, transporting power of running, , - . waveney, england, valley of the, . wealden formation, . weasel, . wells, england, . western reserve historical society, . weston, w. va., . west virginia, _et seq._; glacial terrace in, . wey, valley of the, . whitby, england, . white, cited, _et seq._ white river, ind., , . white sea, . whitney, , , , , . whittlesey, . wild-boar, . wild-cat, . winchell, alexander, cited, , . winchell, n. h., cited, , , ; on the falls of st. anthony, _et seq._ wisconsin, , , , . woeikoff, cited, . wolf, , . wolverine, . wood, cited, . woodward, quoted, ; on age of niagara, _et seq._ wookey hole, england, . wrangell, cited, . wright, . yankton, . yellowstone park, . yorkshire, , , , , , , , . yosemite park, , . young, rev. mr., . young, professor, cited, . younglove, . zermatt glacier, view of, . zuyder zee, . the end. * * * * * d. appleton & co.'s publications. _the ice age in north america, and its bearings upon the antiquity of man._ by g. frederick wright, d. d., ll. d., f. g. s. a., professor in oberlin theological seminary; assistant on the united states geological survey. with an appendix on "the probable cause of glaciation," by warren upham, f. g. s. a., assistant on the geological surveys of new hampshire, minnesota, and the united states. new and enlarged edition. with maps and illustrations. vo, pages, and index. cloth, $ . . "not a novel in all the list of this year's publications has in it any pages of more thrilling interest than can be found in this book by professor wright. there is nothing pedantic in the narrative, and the most serious themes and startling discoveries are treated with such charming naturalness and simplicity that boys and girls, as well as their seniors, will be attracted to the story, and find it difficult to lay it aside."--_new york journal of commerce_. "one of the most absorbing and interesting of all the recent issues in the department of popular science."--_chicago herald_. "though his subject is a very deep one, his style is so very unaffected and perspicuous that even the unscientific reader can peruse it with intelligence and profit. in reading such a book we are led almost to wonder that so much that is scientific can be put in language so comparatively simple."--_new york observer_. "the author has seen with his own eyes the most important phenomena of the ice age on this continent from maine to alaska. in the work itself, elementary description is combined with a broad, scientific, and philosophic method, without abandoning for a moment the purely scientific character. professor wright has contrived to give the whole a philosophical direction which lends interest and inspiration to it, and which in the chapters on man and the glacial period rises to something like dramatic intensity."--_the independent_. "... to the great advance that has been made in late years in the accuracy and cheapness of processes of photographic reproduction is due a further signal advantage that dr. wright's work possesses over his predecessors'. he has thus been able to illustrate most of the natural phenomena to which he refers by views taken in the field, many of which have been generously loaned by the united states geological survey, in some cases from unpublished material; and he has admirably supplemented them by numerous maps and diagrams."--_the nation_. _man and the glacial period._ by g. frederick wright, d. d., ll. d., author of "the ice age in north america," "logic of christian evidences," etc. international scientific series. with numerous illustrations. mo. cloth, $ . . "it may be described in a word as the best summary of scientific conclusions concerning the question of man's antiquity as affected by his known relations to geological time."--_philadelphia press_. 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"prof. wright's work is great enough to be called monumental. there is net a page that is not instructive and suggestive. it is sure to make a reputation aboard as well as at home for its distinguished author, as one of the most active and intelligent of the living students of natural science and the special department of glacial action."--_philadelphia bulletin_. _the great ice age, and us relation to the antiquity of man._ by james geikie, f. r. s. e., of h. m. geological survey of scotland. with maps and illustrations. mo. cloth, $ . . a systematic account of the glacial epoch in england and scotland, with special reference to its changes of climate. _the cause of an ice age._ by sir robert j. ball, ll. d., f. r. s., royal astronomer of ireland, author of "starland." the first volume in the modern science series, edited by sir john lubbock. mo. cloth, $ . . 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"the author admits that there are , separate treatises on the horse already published, but he thinks that he can add something to the amount of useful information now before the public, and that something not heretofore written will be found in this book. the volume gives a large amount of information, both scientific and practical, on the noble animal of which it treats."--_new york commercial advertiser_. _the oak:_ a study in botany. by h. marshall ward, f. r. s. with illustrations. 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"that realm of mystery and wonders at the bottom of the great waters is gradually being mapped and explored and studied until its secrets seem no longer secrets. . . . this excellent book has a score of illustrations and a careful index to add to its value, and in every way is to be commended for its interest and its scientific merit."--_chicago times_. each, mo, cloth, $ . . new york: d. appleton & co., fifth avenue. * * * * * transcriber note figure captions were standardized. all figures were moved to avoid splitting paragraphs. any minor typos were corrected. transcriber's note: a list of corrections is at the end of the text. italics are indicated by _underscores_, bold by =equal signs= and superscripts by '^'. _illogical geology_ _the weakest point in_ _the evolution theory_ [illustration: author] by george mccready price editor of "the modern heretic," and author of "outlines of modern science and modern christianity." the modern heretic company s. hill street, los angeles, cal. single copies ^c copies c: copies $ . illogical geology the weakest point in the evolution theory to the reader. this _advance edition_ has been issued by the publishers in this cheap form to enable them to get out several thousand copies for critical review at comparatively small expense. succeeding editions will be in regular book form, and will be sold at the usual rates for bound volumes. "it is a singular and a notable fact, that while most other branches of science have emancipated themselves from the trammels of metaphysical reasoning, the science of geology still remains imprisoned in '_a priori_' theories."--_sir henry howorth: "the glacial nightmare and the flood." preface. vii._ _the modern heretic company_ s. hill st., los angeles, california copyright by george mccready price los angeles, cal. part i preface this book is not written especially for geologists or other scientists as such, though it deals with the question which it discusses from a purely scientific standpoint, and presupposes a good general knowledge of the rocks and of current theories. it is addressed rather to that large class of readers to whom geology is only an incident in larger problems, and who are not quite wholly satisfied with those explanations of the universe which are now commonly accepted on the testimony of biological science. i am free to say that my own conviction of the higher value and surer truth of other data outside of the biological sciences have always been given formative power in my own private opinions, and that in this way i have long held that there =must be something wrong= with the evolution theory, and also that there must be a surer way of gauging the value of that theory, even from the scientific standpoint, than the long devious processes connected with darwinism and biology. some years ago, when compelled to investigate the subject more fully than i had hitherto done, i discovered, somewhat to my own surprise, the phenomenal weakness of the geological argument. the results of that investigation have grown into the present work. though mostly critical and analytic, it is not wholly so. but so far as it is constructive there is one virtue which can rightly be claimed for it. it is at least an honest effort to study the foundation facts of geology from the inductive may be standpoint, and whether or not i have succeeded in this, it is, so far as i know, the only work published in the english or any other language which does not treat the science of geology more or less as a cosmogony. that such a statement is possible is, i think, my chief justification in giving it to the public. it would seem as if the twentieth century could afford at least one book built up from the present, instead of being postulated from the past. george mccready price. south hill street, los angeles, california, june, . contents part i i the abstract idea ii history of the idea iii fact number one iv fact number two v turned upside down v fact number four vii extinct species viii skipping part ii ix graveyards x change of climate xi degeneration xii fossil men xiii inductive methods appendix introduction a brief outline of the argument which i have used in the following pages will be in order here. darwinism, as a part, the chief part, of the general evolution theory, rests logically and historically on the succession of life idea as taught by geology. if there has actually been this succession of life on the globe, then some form of genetic connection between these successive types is the intuitive conclusion of every thinking mind. but if there is no positive evidence that certain types are essentially older than others, =if this succession of life is not an actual scientific fact=, then darwinism or any other form of evolution has no more scientific value than the vagaries of the old greeks--in short, from the standpoint of true inductive science it is a most gigantic hoax, historically scarce second to the ptolemaic astronomy. in part one i have examined critically this succession of life theory. it is improper to speak of my argument as destructive, for there never was any real constructive argument to be thus destroyed. it is essentially =an exposure=, and i am willing to =give a thousand dollars= to any one who will, in the face of the facts here presented, show me how to prove that one kind of fossil is older than another. in part two i have attempted to build up a true, safe induction in the candid, unprejudiced spirit of a coroner called upon to hold a _post mortem_. the abnormal character of most of the fossiliferous deposits, the sudden world-wide change of climate they record, the marked degeneration in all organic forms in passing from the older to the modern world, together with the great outstanding fact that human beings, with thousands of other living species of animals and plants have at this great world-crisis left their fossils in the rocks all over the world, prove beyond a possible doubt that our once magnificently stocked world met with a tremendous catastrophe some thousands of years ago, before the dawn of history. as for the =origin= of the living beings that existed before that event, we can only suppose a =direct creation=, since modern science knows nothing of the spontaneous generation of life, or of certain types of life having originated =before= other types, and thus being able to serve as =the source of origin= of other alleged succeeding types. with the myth of a life succession dissipated once and for ever, the world stands face to face with creation as the direct act of the infinite god. chapter i the abstract idea how many of us have ever tried to think out a statement of just how we would prove that there has been a succession of life on the globe in a particular order? herbert spencer did[ ] and he did not seem to think the way in which it is usually attempted a very praiseworthy example of the methods to be pursued in natural science. he starts out with werner, of neptunian fame, and shows that the latter's main idea of the rocks always succeeding one another over the whole globe like the coats of an onion was "untenable if analyzed," and "physically absurd," for among other things it is incomprehensible that these very different kinds of rocks could have been precipitated one after another by the same "chaotic menstrum." but he then proceeds to show that the science is "still swayed by the crude hypotheses it set out with; so that even now, old doctrines that are abandoned as untenable in theory, continue in practice to mould the ideas of geologists, and to foster sundry beliefs that are logically indefensible." werner had taken for his data the way in which the rocks happened to occur in "a narrow district of germany," and had at once jumped to the conclusion that they must always occur in this relative order over the entire globe. "thus on a very incomplete acquaintance with a thousandth part of the earth's crust, he based a sweeping generalization applying to the whole of it." werner classified the rocks according to their mineral characters, but when the fossils were taken as the prime test of age, the "original nomenclature of periods and formations" kept alive the original idea of complete envelopes encircling the whole globe one outside each other like the coats of an onion. so that now, instead of werner's successive ages of sandstone making or limestone making, and successive suites of these rocks, we have successive ages of various types of life, with successive systems or "groups of formations which everywhere succeed each other in a given order; and are severally everywhere of the same age. though it may not be asserted that these successive systems are universal, yet it seems to be tacitly assumed that they are so.... though, probably, no competent geologist would contend that the european classification of strata is applicable to the globe as a whole; yet most, if not all geologists, write as though it were so." spencer then goes on to show how dogmatic and unscientific it is to say that when the carboniferous flora, for example, existed in some localities, this type of life and this only must have enveloped the world. "now this belief," he says, "that geologic 'systems' are universal, is quite as untenable as the other. it is just as absurd when considered _a priori_: and it is equally inconsistent with the facts," for all such systems of similar life-forms must in olden time have been of merely "local origin," just as they are now. in other words, we have no scientific knowledge of a time in the past when there were not zoological provinces and zones as there are to-day, one type of life existing in one locality, while another and totally different type existed somewhere else. then, after quoting from lyell a strong protest against the old fancy that only certain types of sandstone and marls were made at certain epochs, he proceeds: "nevertheless, while in this and numerous passages of like implication, sir c. lyell protests against the bias here illustrated, he seems himself not completely free from it. though he utterly rejects the old hypothesis that all over the earth the same continuous strata lie upon each other in regular order, like the coats of an onion, he still writes as though geologic 'systems' do thus succeed each other. a reader of his 'manual' would certainly suppose him to believe, that the primary epoch ended, and the secondary epoch commenced, all over the world at the same time.... =must we not say that though the onion-coat hypothesis is dead, its spirit is tractable, under a transcendental form, even in the conclusions of its antagonists.=" spencer then examines at considerable length the kindred idea that the same or similar species "lived in all parts of the earth at the same time." "this theory," he says, "is scarcely more tenable than the other." he then shows how in some localities there are now forming coral deposits, in some places chalk, and in others beds of molluscs; while in still other places entirely different forms of life are existing. in fact, each zone or depth of the ocean has its particular type of life, just as successive altitudes do on the sides of a mountain; and it is a dogmatic and arbitrary assumption to say that such conditions have not existed in the past. "on our own coasts, the marine remains found a few miles from shore, in banks where fish congregate, are different from those found close to the shore, where only littoral species flourish. a large proportion of aquatic creatures have structures that do not admit of fossilization; while of the rest, the great majority are destroyed, when dead, by the various kinds of scavengers that creep among the rocks and weeds. so that no one deposit near our shores can contain anything like a true representation of the fauna of the surrounding sea; much less of the co-existing faunas of other seas in the same latitude; and still less of the faunas of seas in distant latitudes. were it not that the assertion seems needful, it would be almost absurd to say that the organic remains now being buried in the dogger bank can tell us next to nothing about the fish, crustaceans, mollusks, and corals that are now being buried in the bay of bengal." this author evidently found it difficult to keep within the bounds of parliamentary language when speaking of the absurd and vicious reasoning at the very basis of the whole current geological theory; for, unlike the other physical sciences, the great leading ideas of geology are not generalisations framed from the whole series or group of observed facts, but are really abstract statements supposed to be reasonable in themselves, or at the most =very hasty conclusions based on wholly insufficient data=, like that of werner in his "narrow district of germany." sir henry howorth[ ] has well expressed the urgent need that there is of a complete reconstruction of geological theory: "it is a singular and a notable fact, that while most other branches of science have emancipated themselves from the trammels of metaphysical reasoning, the science of geology still remains imprisoned in _a priori_ theories." but huxley[ ] also has left us some remarks along the same line which are almost equally helpful in showing the essential absurdity of the assumption that when one type of life was living and being buried in one locality another and very diverse type could not have been doing the same things in other distant localities. this is how he expresses it: "all competent authorities will probably assent to the proposition that physical geology does not enable us in any way to reply to this question--were the british cretaceous rocks deposited at the same time as those of india, or were they a million of years younger, or a million of years older?" this phase of the idea, however, is not so bad, for the human mind refuses to believe that distant and disconnected groups of similar forms were not connected in time and genetic relationship. it is really the reverse of this proposition that contains the most essential absurdity, and this is the very phase that is most essential to the whole succession of life idea. huxley, indeed, seems to have caught a glimpse of this truth, for he says: "a devonian fauna and flora in the british islands =may= have been contemporaneous with silurian life in north america, and with a carboniferous fauna and flora in africa. =geographical provinces and zones may have been as distinctly marked in the palaeozoic epoch as at present.=" certainly; but if this be true, it is equally certain that the carboniferous flora of pennsylvania may have been contemporaneous alike with the cretaceous flora of british columbia and the tertiary flora of germany and australia. but in that case what becomes of this succession of life which for nearly a century has been the pole star of all the other biological sciences--i might almost say of the historical and theological as well? must it not be admitted that in any system of clear thinking this whole idea of there having really been a succession of life on the globe is not only =not proved= by scientific methods, but that it is essentially unprovable and absurd? huxley, in point of fact, admits this, though he goes right on with his scheme of evolution, just as if he never thought of the logical consequences involved. his words are: "in the present condition of our knowledge and of our methods (_sic_) one verdict--'=not proven and not provable='--must be recorded against all grand hypotheses of the palaeontologist respecting the general succession of life on the globe." in view of these startling facts, is it not amazing to see the supernatural knowledge of the past continually and quietly assumed in every geological vision of the earth's history? footnotes: [ ] "illogical geology; illustrations of universal progress," pp. - ; d. appleton & co., . [ ] "the glacial nightmare and the flood," preface vii. [ ] "discourses biol. and geol.," pp. - . chapter ii history of the idea among the few stray principles that the future will probably be able to save from the wreck of spencer's philosophy, is the advisability of looking into =the genealogy of an idea=. what has been its surroundings? what is its family history? does it come of good stock, or is its family low and not very respectable? this is especially true in the case of a scientific idea, which above all others needs to have a clean bill of health and a good family record. but, unfortunately, the idea we are here considering has a bad record, very bad in fact; for the whole family of cosmogonies, of which this notion is the only surviving representative, were supposed to have been banished from the land of science long ago, and were all reported dead. some of them had to be executed by popular ridicule, but most of them died natural deaths, the result of inherited taint, in the latter part of the eighteenth and early nineteenth centuries. it is perfectly astonishing how any of the family could have survived over into the twentieth century, in the face of such an antecedent record. for one of the chief traits of the family as a whole is that of mental disorder of various stages and degrees. some of them were raving crazy; others were mild and comparatively harmless, except that their drivel had such a disturbing effect on scientific investigations that they had to be put out of the way. it seems such a pity that when this last fellow, early in life, was up before doctors huxley and spencer for examination, he was not locked up or put in limbo forthwith. this is especially unfortunate, because this survivor of an otherwise extinct race has since then produced a large family, some of which it is true have already expired, while the eldest son, darwinism, was reported in to be "at its last gasp,"[ ] and was even said last year to have had its "tombstone inscription" written by von hartmann of germany. but the succession of life idea itself, the father of all this brood, is still certified by those in authority to be healthy and _compos mentis_. the cosmogony family is a very ancient one, running back to the time of plato and thales of miletus. indeed the cuneiform inscriptions of babylonia seem to indicate that a tribe with very similar characteristics existed several millenniums before the christian era. but discarding all these, the first men that we need to mention are perhaps burnet and whiston, who knew no other way of arriving at geological truth than to spin a yarn about how the world was made. woodward seems to have had a little better sense, and is named along with hooke and john ray as one of the real founders of the science. unfortunately the brood of cosmogonists was not dead, for moro and de maillet were at this same period spinning their fantastic theories about the origin of things; or as zittel puts it, "accepted the risks of error, and set about explaining the past and present =from the subjective standpoint=."[ ] this tendency we will find to be a birthmark in the family, and will serve to invariably identify any of them wherever found. we must remember this, and apply the test to the modern survivors. buffon seems to have been really the founder of the family in the modern form. he is credited with the sarcastic remark that "geologists must feel like the ancient roman augurs who could not meet each other without laughing;" though in view of his fantastic scheme of seven "epochs," in which he endeavors to portray "the beginning, the past, and the future (_sic_) of our planet,"[ ] one is reminded of the common symptom which manifests itself in thinking all the rest of the world crazy. the "heroic age of geology" succeeded this period, and was characterized largely by a determination to discard speculation, and to seek to build up a true science of actual fact and truth. we have already seen from spencer's remarks that a. g. werner, who was, however, one of the leaders in germany at this time, was very far from following true inductive methods. and the following language of sir arch. geikie shows that in him the family characteristics were decidedly prominent: "but never in the history of science did a stranger hallucination arise than that of werner and his school, when they supposed themselves to discard theory and build on a foundation of accurately-ascertained fact. never was a system devised in which theory was more rampant; theory, too, unsupported by observation, and, as we now know, utterly erroneous. from beginning to end of werner's method and its applications, assumptions were made for which there was no ground, and these assumptions were treated as demonstrable facts. =the very point to be proved was taken for granted=, and the geognosts, who boasted of their avoidance of speculation, were in reality among the most hopelessly speculative of all the generations that had tried to solve the problem of the theory of the earth."[ ] in fact this author says that: "the wernerians were as certain of the origin and sequence of the rocks as if they had been present at the formation of the earth's crust." (pp. - .) here we see the family characteristics very strongly developed. in speaking of werner's five successive "suites" or onion-coats in which he wrapped his embryo world, zittel complains: "unfortunately, werner's field observations were =limited to a small district=, the erz mountains and the neighboring parts of saxony and bohemia. and his chronological scheme of formations was founded upon the mode of occurrence of the rocks within these narrow confines." (p. .) and yet, as we have seen, it is precisely such a charge as this that spencer and huxley bring against the modern phase of the doctrine of successive ages based on the succession of life idea. werner, from observations "limited to a small district," constructed his scheme of exact chronological sequence, basing it entirely upon the mineral or mechanical character of his "suites." and hundreds of enthusiastic followers long declared that the rocks everywhere conformed to this classification, even so great an observer as von humboldt thinking that the rocks which he examined in central and south america fully confirmed werner's chronological arrangement. but such notions to-day only cause a smile of pity, for it is now well known that, take the world over, =the rocks do not occur= as werner imagined, though, as geikie says, he and his disciples were as certain of the matter "as if they had been present at the formation of the earth's crust." besides, as already pointed out, we moderns ought now to have pretty well assimilated the idea that while one kind of mineral or rock was forming in one locality, =a totally different kind of deposit= may have been in process of formation in another spot some distance off =at the very same time=, and we cannot imagine a time in the past when this principle would not hold good. but in a precisely similar way the idea of a time value was, as we shall see, transferred from the mechanical and mineral character of the rocks to their fossil contents; and from observations again "limited to a small district," william smith and cuvier conceived the idea that the fossils occurred =only= in a certain order; that only certain fossils lived at a certain time; that, for example, while trilobites were living and dying in one locality, nummulites or mammals positively were not living and dying in another locality, though in any system of clear thinking this latter notion is just as irrational as that of werner. hence spencer is compelled to say, "though the onion-coat hypothesis is dead, its spirit is still traceable, under a transcendental form, even in the conclusions of its antagonists." the two cases are exactly parallel; only it has taken us nearly a hundred years, it seems, to find out that the fossils do not follow the prearranged order of smith and cuvier any better than the rocks and minerals do the scheme of werner. if hundreds of geologists still seem to think that the fossils in general agree with the standard order, we must remember how many sharp observers said the same thing for decades about werner's scheme. the taint of heredity will always come out sooner or later; and both of these schemes exhibit very strongly the family history of the whole tribe of cosmogonies, viz., =the facts refuse to certify that they are of sound mind=. it was william smith, an english land surveyor, who first conceived the idea of fixing the relative ages of strata by their fossils. just how far he carried this idea it seems difficult to determine exactly. lyell[ ] says nothing along this line about him, save that he followed the leading divisions of the secondary strata as outlined by werner, though he claims "independently" of the latter. whewell[ ] remarks rather pityingly on his having had "no literary cultivation" in his youth, but has nothing about the degree in which he is responsible for the modern scheme of life succession of which many modern geologists have made him the "father". geikie and zittel are much more explicit. the former[ ] says that "he had reached early in life the conclusions on which his fame rests, and he never advanced beyond them." "his plain, solid, matter-of-fact intellect never branched into theory or speculation, but occupied itself wholly in the observation of facts." zittel[ ] says pretty much the same thing, remarking that "smith confined himself to the empirical investigation of his country, and was never tempted into general speculations about the history of the formation of the earth"--words which to my mind are the very highest praise, for they seem to indicate that he was only in a very limited way responsible for the unscientific and illogical scheme of a "phylogenic series" or complete "life-history of the earth," which now passes as the science of geology. doubtless like his little bright-eyed german contemporary, a. g. werner, he had not had his imagination sufficiently cultivated in his youth to be able to appreciate the beauty of first assuming your premises and then proving them by means of your conclusion, i.e., first assuming that there has been a gradual development on the earth from the lowest to the highest, and then arranging the fossils from scattered localities over the earth in such a way that they cannot fail to testify to the fact. the following may be taken as a fair statement of what he actually accomplished and taught: "after his long period of field observations, william smith came to the conclusion that one and the same succession of strata stretched through england from the south coast to the east, and that each individual horizon could be recognized by its particular fossils, that certain forms reappear in the same beds in the different localities, and that each fossil species belongs to a definite horizon of rock."[ ] but even granting the perfect accuracy of this generalization of smith's for the rocks which he examined, i fail to see how it is any better than werner's scheme, which zittel characterizes as "weak" and premature, and of which whewell (p. ) says that "he promulgated, as respecting the world, a scheme collected from a province, and even too hastily gathered from that narrow field." quoting again from zittel's criticism of werner's work ("hist. of geology," p. ), we must admit that smith's observations also were "limited to a small district," and "his chronological scheme of formations was founded upon the mode of occurrence of the rocks (fossils) within these narrow confines." there is, as we have shown, a monstrous jump from this to the conclusion that =even these particular fossils= must always occur in this particular relative order over the whole earth. how can any one deny that if we had a complete collection of all the fossils laid down during the last thousand years--when all admit that the so-called "phylogenic series" is complete--particular fossils would in many cases be found to occur only in particular rocks, and we could still arrange them in this same order from the lowest to the highest forms of life, while we might even happen to find "small districts" where the "mode of occurrence of the rocks within these narrow confines" would have all the appearance of showing a true "phylogenic" order. this of itself ought to be sufficient to show us the weakness of this subjective method of study, and the purely hypothetical and imaginary value of the fossils in determining the real age of a rock deposit. the name of baron cuvier is the next that we have to consider. an examination of part of his teaching will come naturally a little later when considering "extinct species." that part of his work which related to the doctrine of catastrophism is somewhat aside from the subject of our study; while with regard to his influence on the succession of life idea _per se_ there is not very much that need be said. and yet cuvier is the real founder of modern cosmological geology, and thus in a certain sense the father of biological evolution. but if the absence of the architectonic mania for building a cosmogony will serve to remove in a great measure any suspicions with regard to william smith's results, we cannot say the same for those of cuvier. in his scheme the hereditary cosmological taint, which is such an invariable characteristic of the family, is very strong, though disguised and almost transfigured by learning and genius. it is doubtless these latter qualities which have secured for the theory such a phenomenal length of life, though of course we know that nothing born of this whole brood can ever secure a permanent home in the kingdom of science. "how glorious," wrote this otherwise truly great man in his famous "preliminary discourse," "it would be if we could arrange the organized products of the universe in their chronological order, as we can already (werner's onion-coats) do with the more important mineral substances!" his work (with that of his co-laborer brongniart) on the fossils of the paris basin was probably accurate and logical enough for that limited locality. it was only when he quietly assumed as werner had done, that the rocks must always occur in this particular order all over the world, or as whewell expresses it, "promulgated as respecting the world, a scheme collected from a province, and (perhaps) even too hastily gathered from that narrow field"--it was only, i say, when this monstrous assumption was incorporated into his scheme, and he began to call into being his vision of organic creation on the instalment plan, as werner had done with the minerals, that his great and valuable work for science became tainted with the deadly cosmological virus, dooming it to death sooner or later. sherlock holmes might attempt to diagnose a disease by a mere glance at his patient's boots, but even this gave him more data and was a more logical proceeding than the facts and methods of cuvier supplied for constructing a scheme of organic creation. it will not be necessary to detail the manner in which the modern "phylogenic series" was gradually pieced together from the scattered fragments here and there all over the globe; but it should be noted here that the whole chain of life was practically complete before any serious attempt was made to study the rocks on the top of the ground, and to find out how this marvellous record of the past =joined on to the modern period=, thus reversing completely the true inductive method, and leaving the most important of all, viz., the rocks containing human remains and other living species, over till the last, with the result that we have for over half a century been laboring under a "glacial nightmare," and these deposits on the top of the ground "still remain in many respects the despair of geology." then came lyell, agassiz, and darwin; and now in the light of the keen discussions instituted by weismann in the later eighties of the last century, the modern world is pretty well agreed on two results, viz., that so far from natural selection being able to originate a species, it can't possibly =originate= anything at all, and also that no individual can transmit to his descendants what he has himself acquired in his lifetime, and hence it is hard to see how he can transmit what he has not got himself and what none of his ancestors ever had. i have not the space to show how agassiz further complicated the problem immensely by his absurdly illogical use of his three "laws" of comparison, when the prime fact of there ever having been a succession of life on the globe in any order whatever had never been proved; but i am free to say that if cuvier's system of creation on the instalment plan had been fact instead of fancy, some scheme of evolution would undoubtedly be implied in this general fact. it is this instinctive feeling on the part of modern scientists which makes them to-day, while confessing the failure of darwinism, still cling to the general idea of evolution =somehow=. hence it seems quite evident that, having deviated from strict inductive methods by pursuing this _ignis fatuus_ of a cosmological history of creation, it was essential in the interests of true science to go the whole journey and make a complete investigation of the biological side of the question, in order to complete the demonstration that science was on a wrong tack entirely. darwin and weismann were inevitable in view of the wholly unscientific course on which biology entered under the guidance of buffon and cuvier. what then can we take as the general lesson to be learned from the stubborn way in which, for over a hundred years, the world has followed this hypnotic suggestion of folly, that we might explain our genesis and being from the scientific standpoint? one of the lessons--there may be others--is that =science knows nothing about origins=, and that, in speculating along these lines, the cosmological taint will always vitiate the accuracy of our conclusions and debauch the true spirit of induction. a hundred years ago, they thought they knew all about how the world was made. the keen investigations inspired by darwinism were necessary to convince us that we know nothing at all about it. modern biology has simply developed a gigantic _reductio ad absurdum_ argument against the easy assumptions of the earlier geologists that it occurred by a progression from the low to the high. a hundred years--nay fifty years ago--this assumption did not appear so unscientific, for we did not then have the biological evidence to refute such an idea. now, however, in the light of the modern progress of science, this awful mystery of our existence, of our creation and destiny, is borne in upon us from every dividing cell, from every sprouting seed, from countless millions of the eloquent voices of nature, which our forefathers were too blind to see, too deaf to understand; and with weary, reluctant sadness does science confess that about it all she knows absolutely nothing. footnotes: [ ] nature, nov. , , pp. , . [ ] "history of geology," p. . [ ] zittel, p. . [ ] "founders of geology," p. ; johns hopkins press, . [ ] "principles," p. , th ed. [ ] "history of the inductive sciences," vol. ii., p. . [ ] "founders of geology," pp. - . [ ] "history," p. . [ ] zittel, "history," p. . it should be noted that all these rocks in england thus examined by smith make up only a small fraction of the total geological series--largely what we now call the jurassic and cretaceous rocks. chapter iii fact number one hitherto we have been dealing only with the _a priori_ aspects of the succession of life idea. we have seen that it is really based on two primary assumptions, viz.: ( ) that over all the earth the fossils =must always occur= in the particular order in which they were found to occur in a few corners of western europe; and also-- ( ) that in the long ago =there were no such things as zoological provinces and zones=, and totally different types of fossils from separated localities could not possibly have been contemporaneous with one another as we know they are to-day in "recent" deposits.[ ] on the blending of these two assumptions, the latter essentially absurd, and the former long ago disproved by the facts of the rocks, has been built up the towering structure of a complete "phylogenic series" from the cambrian to the pleistocene. the way in which, as we have been, spencer and huxley treated this subject, reminds us very much of the old advice, "when you meet with an insuperable difficulty, look it steadfastly in the face--and pass on." for neither they nor any of their thousands of followers have ever, so far as i know, pointed out the horrible logic in taking this immense complex of guesses and assumptions as the starting-point for new departures, the solid foundation for detailed "investigations" as to =just how= this wonderful phenomenon of development has occurred. for after agassiz and his contemporaries had built on these large assumptions of cuvier, and had arranged the details and the exact order of these successive forms by comparison with the embryonic life of the modern individual, the evolutionists of our time, led by such men as spencer and haeckel, with their "philogenetic principle," =prove= their theory of evolution by showing that the embryonic life of the individual is only "a brief recapitulation, as it were from memory," of the geological succession in time. there would really seem to be little hope of reaching with any arguments a generation of scientists who can elaborate genealogical trees of descent for the different families and genera of the animal kingdom, based wholly on such a series of assumptions and blind guesses, and then palm off their work on a credulous world as the proved results of =inductive= science. and yet i am tempted to make some effort in this direction. and since we have now examined the _a priori_ aspects of the question, it remains to test the two above mentioned assumptions by the facts of the rocks. the =second=, indeed, involving as it does a profound supernatural knowledge of the past, and being so positively contrary to all that we know of the modern world as to seem essentially absurd, is yet by its very nature beyond the reach of any tests that we can bring to bear upon it. hence it remains to test by the facts of the rocks =the assumption that all over the earth the fossils invariably occur in the particular order in which they were first found in a few corners of western europe= by the founders of the science. have we already a sufficiently broad knowledge of the rocks of the world to decide such a question? i think we have. to begin then at the beginning, let us try to find out how we can fix on the rocks which are absolutely the oldest on the globe. we would expect to find a good many patches of them here and there, but there must be some common characteristic by which they may be distinguished wherever found. of course, when i say "rocks" here i mean fossils, for as has long been agreed upon by geologists, mineral and mechanical characters are of practically no use in determining the age of deposits, and we are here dealing only with life and the order in which it has occurred on the globe. accordingly our problem is really to find that typical group of fossils which is essentially older than all dissimilar groups of fossils. in most localities we do not have to go very far down[ ] into the earth to find granite or other so-called igneous rocks, which not only do not contain any traces of fossils, but which we have no proper reason for supposing ever contained any. these azoic or archaean rocks constitute practically all the earth's crust, there being only a thin skim of fossiliferous strata on the outside somewhat like the skin on an apple. now it would be natural enough to suppose that those fossils which occur at the bottom, or next to the archaean, are the oldest. this is doubtless what the earlier geologists had in mind, or at least ought to have had, for it is not quite certain that they had any clear thoughts on the matter whatever. they did not really begin at the bottom, but half way up, so to speak, at the mesozoic and tertiary rocks, and sedgwick and murchison, who undertook to find bottom, got too excited over their cambro-silurian controversy to attend to such an insignificant detail as the logical proof that any type of fossils was really older than all others. if they had really stopped to consider that some type of fossil might occur next to the archaean in wales, and another type occur thus in scotland, while still another type altogether might be found in this position in some other locality, and so on over the world, leading us to the very natural conclusion that in the olden times as now =there were zoological provinces and districts=, the history of science during the nineteenth century might have been very different, and this chapter might never have been written. but this commonplace of modern geology, that any type of fossil whatever, even the very "youngest," may occur next to the archaean, was not then considered or understood; and when about it came to be recognized, other things were allowed to obscure its significance, and the habit of arranging the rocks in chronological order according to their fossils was too firmly established to be disturbed by such an idea. but the fact number one, which i have chosen as the subject of this chapter, is the now well established principle that =any kind of fossil whatever, even "young" tertiary rocks, may rest upon the archaean or azoic series, or may themselves be almost wholly metamorphosed or crystalline, thus resembling in position and outward appearance the so-called "oldest" rocks=. the first part of this proposition, about any rocks occurring next to the archaean, is covered by the following quotation from dana:[ ] "a stratum of one era may rest upon any stratum in the whole of the series below it,--the coal-measures on either the archaean, silurian, or devonian strata; and the jurassic, cretaceous, or tertiary on any one of the earlier rocks, the intermediate being wanting. the quaternary in america in some cases rests on archaean rocks, in others on silurian or devonian, in others on cretaceous or tertiary." it would be tedious to multiply testimony on a point so universally understood. as for the other half of this fact, that even the so-called "youngest" rocks may be metamorphic and crystalline just as well as the "oldest," it also is now a recognized commonplace of science. dana[ ] says that as early as lyell taught this as a general truth applicable to "all the formations from the earliest to the latest." the first reference i can find to any disproof of this old fable of werner's, that only certain kinds of rock are to be found next to the "primitive" or archaean, is in the observations of studer and beaumont in the alps, ( - ), who found "relatively young" fossils in crystalline schists, which, as zittel says, "was a very great blow to the geologists who upheld the hypothesis of the archaean or pre-cambrian age of all gneisses and schists." james geikie, doubtless referring to the same series of rocks, tells us that:-- "in the central alps of switzerland, some of the eocene strata are so highly metamorphosed that they closely resemble some of the most ancient deposits of the globe, consisting, as they do, of crystalline rocks, marble, quartz-rock, mica schist, and gneiss."[ ] hence we need not be surprised at the following statement of the situation by zittel.[ ] "the last fifteen years of the nineteenth century witnessed very great advances in our knowledge of rock-deformation and metamorphism. =it has been found that there is no geological epoch whose sedimentary deposits have been wholly safeguarded from metamorphic changes=, and, as this broad fact has come to be realized, it has proved most unsettling, and has necessitated a revision of the stratigraphy of many districts in the light of new possibilities. the newer researches scarcely recognize any theory; they are directed rather to the empirical method of obtaining all possible information regarding microscopic and field evidences of the passage from metamorphic to igneous rocks, and from metamorphic to sedimentary rocks." but in addition to what zittel means by recognizing "no theory" as to the origin of the various sorts of "igneous" rocks, it seems to me that this "broad fact" ought surely to prove "most unsettling," to the traditional theories about certain fossils being intrinsically older than others. with our minds divested of all prejudice, and this "broad" fact number one well comprehended, that any kind of fossil whatever may occur next to the archaean, and the rocky strata containing it may in texture and appearance "closely resemble some of the most ancient deposits on the globe," =where= on this broad earth shall we look for the place =to start= our life-succession that is, where can we now go to find those kinds of fossils which we can prove, by independent arguments, to be absolutely older than all others? it may seem very difficult for some of us to discard a theory so long an integral part of all geology; but until it can be proved that this "broad fact" as stated by zittel and dana is no fact at all, i see no escape from the acknowledgment that the doctrine of any particular fossils being essentially older than others is a pure invention, with absolutely nothing in nature to support it. or, to state the matter in another way, since the life succession theory rests logically and historically on werner's notion that only certain kinds of rocks (fossils) are to be found at the "bottom" or next to the archaean, and it is now acknowledged everywhere that any kind of rocks whatever may be thus situated, it is as clear as sunlight that the life succession theory rests logically and historically on a myth, and that there is =no way of proving what kind of fossil was buried first=. of course, the reason the followers of cuvier and his life succession now find themselves in such a fix as this is because they have not been following true inductive methods. theirs has been a geology by hypothesis instead of by observed fact. they started out with a pretty scheme ready-made about the origin and formation of the world, perfectly innocent of any evil intent in such a method of procedure, and unconscious of its speculative character; and for nearly a hundred years they have supposed that they were following inductive methods in geology. but in view of what we have now learned i think we are perfectly justified in adapting and applying to cuvier and the modern school of geologists what geikie[ ] says about werner and his school: "but never in the history of science did a stranger hallucination arise than that of cuvier and the modern school, when they supposed themselves to discard theory and build on a foundation of accurately ascertained fact. never was a system devised in which theory was more rampant; theory, too, unsupported by observation, and, as we now know, utterly erroneous. from beginning to end of cuvier's method and its applications, assumptions were made for which there was no ground, and these assumptions were treated as demonstrable facts. the very point to be proved was taken for granted, and the evolutionary geologists who boasted of their avoidance of speculation, were in reality among the most hopelessly speculative of all the generations that had tried to solve the problem of the theory of the earth." footnotes: [ ] the onion-coat hypothesis, which is the only other alternative, modern science professes to have abandoned. [ ] when the text-books speak of ten or twelve miles thickness of the fossiliferous rocks, the reader should remember how the rocks have to be patched up together from here and there to make this incredible thickness, as only a small fraction of such a thickness exists in any one place. [ ] "manual," p. , fourth ed. [ ] "manual," p. . [ ] "manual of historical geol.," p. . [ ] "hist.," p. . [ ] "founders of geology," p. . chapter iv fact number two if we had ample evidence that a certain man was personally acquainted with julius caesar, that they were born in the same town, went to school together, served in the same wars, and later carried on an extensive mutual correspondence, would we not conclude that they must have lived in the same age of the world's history? i confess that the conclusion seems quite unavoidable. who would dream that eighteen centuries or more had separated the two lives, and that while one was an old roman the other was an american of the latter nineteenth century? some such a puzzle as this is presented in geology under the general subject of =conformability=. let me define this term. strata laid down by water are in the first place in a horizontal position. some subsequent force may have disturbed them, so that we may now find them standing up on edge like books in a library. but all human experience goes to show that they were not deposited in this position. some disturbing cause must have taken hold of them since they were laid down, for the water in which they were made must have spread them out smooth and horizontal, each subsequent layer or stratum fitting "like a glove" on the preceding. thus when we find two successive layers agreeing with one another in their planes of bedding, with every indication that the lower one was not disturbed in any way before the upper one was spread out upon it, the two are said to be =conformable=. but if the lower bed has evidently been upturned or disturbed before the other was laid down, or if its surface has even been partly eroded or washed away by the water, the strata are said to be =unconformable=, or they show =unconformability= in bedding. of course, in all this we are dealing only with =relative= time. when we find one bed or stratum lying above another in their natural position, the lower one is of course the older of the two; but whether laid down ten minutes earlier, or ten million years earlier, how are we to determine? ignoring the matter of the fossils they contain, must we not own that, though there is no way of telling just how much longer the lower one was deposited before the next succeeding, yet if the two are conformable to one another, and the bottom one shows no evidence of disturbance or erosion before the other was fitted upon it, the strong presumption would seem to be that no great length of time could have elapsed between the laying down of the two layers. to say that we have here a geological example similar to that of a modern american having been personally acquainted with julius caesar, would seem to be quite "inexplicable," as herbert spencer used to say. but if the life succession theory be true, we have just such a conundrum in our fact number two, which is that =any formation whatever may rest conformably upon any other "older" formation=. the lower may be devonian, silurian, or cambrian, and the upper one cretaceous or tertiary, and thus according to the theory millions on millions of years must have elapsed after the first, and before the following bed was laid down, but the conformability is perfect, and the beds have all the appearance of having followed in quick succession. sometimes, too, though less frequently, these age-separated formations are lithologically the same, and can only be separated by their fossils! but before going into the minute description of any of these cases, we must notice some general statements. thus as long ago as the date of the publication of "the origin of species," darwin, in speaking of the "imperfection of the geological record," could speak of "the many cases on record of a formation conformably covered, after an immense interval of time, by another and later formation, without the underlying bed having suffered in the interval by any wear and tear."[ ] also geikie,[ ] in speaking of how "fossil evidence may be made to prove the existence of gaps which are not otherwise apparent," says that "it is not so easy to give a satisfactory account of those which occur where the strata are strictly conformable, and where no evidence can be observed of any considerable change of physical conditions at the time of deposit. a group of quite conformable strata having the same general lithological characters throughout, may be marked by a great discrepance between the fossils of the upper and the lower part." in many cases he says these conditions are "not merely local, but persistent over wide areas.... they occur abundantly among the european palaeozoic and secondary rocks," and are "traceable over wide regions." we have seen how dana admits that "a stratum of one era may rest upon any stratum in the whole series below it, ... the intermediate being wanting." he classes this under the head of the "=difficulties=" of the science, quite naturally as it would seem, though he does not expressly assert that these age-separated formations are often =conformable= to one another, as geikie and darwin have said in the above given quotations. the literature really teems with illustrations of these facts, and the more detailed accounts contained in the various geological reports are often quite charmingly _naive_ in their description of the conditions. two examples, however, must suffice, both from the canadian north west. the first is from the report on the region about banff, in alberta, near the line of the canadian pacific railway, and just east of the rockies. "east of the main divide the lower carboniferous is overlaid in places by beds of lower cretaceous age, and here again, although the two formations differ so widely in respect to age, one overlies the other without any perceptible break, and the separation of one from the other is rendered more difficult by the fact that the upper beds of the carboniferous =are lithologically almost precisely like those of the cretaceous (above them.) were it not for fossil evidence, one would naturally suppose that a single formation was being dealt with.="[ ] the other example is from the district of athabasca. "the devonian limestone is apparently succeeded conformably by the cretaceous, and with the possible exception of a thin bed of conglomerate of limited extent, which occurs below crooked rapid on the athabasca, the age of which is doubtful, the =vast interval of time= which separated the two formations, is, so far as observed, =unrepresented= either by deposition or erosion."[ ] of course, some geological writers labor to explain this thundering rebuke of their theory, just as the ptolemaic astronomers had their "deterrents" and "epicycles" for every new difficulty. but surely the detailed records of such observations as these are fearful examples of the power of tradition to blind the minds of investigators to the meaning of the very plainest facts. on a previous page (id. p. ,) the author last quoted gives us some idea of the "remarkable persistence" of this instructive case of conformability, which extends from the athabasca "in a broad band around the southern end of birch mountains, and across lake claire to peace river, and up the latter stream to a point two miles above vermillion falls." the distance, as i judge from the map, can not be less than miles in a straight direction, thus making a district of probably several thousand square miles in extent where, according to the theory of a life succession, nature must have put an injunction on the action of the elements, and they had to continue in the _status quo_ for millions of ages, or from the devonian to the cretaceous "age," the water neither wearing away nor building up over any part of this consecrated ground during all this time. nor is this all, for from part e, report (p. ) of this same volume, we are told of strata near lake manitoba, =over miles away=, in almost the same wonderful relationship,--"devonian rocks very similar in character" to those in athabasca still overlaid directly by the cretaceous, though in this case as it happens "unconformably." it would almost seem to be a _bona fide_ case of werner's onion coats cropping out. and all this incredible picture of nature's inconsistent behaviour in past ages is necessitated solely by the loving allegiance with which the infallibility of the life succession theory is regarded by modern geologists. footnotes: [ ] "origin," vol. ii., p. : sixth ed. the first edition, i believe, contains the same language. [ ] "text-book," p. . [ ] canadian "annual report," new series, vol. ii., part a, p. . [ ] "annual report," new series, vol. v., part d, p. . chapter v turned upside down how many of us have ever seen a mountain fall? not very many. and yet events even more wonderful than this have frequently occurred in the past, as we are confidently assured by the leaders in geological science. thus, in speaking of a certain region in the alps, dana[ ] says that "one of the overthrust folds has put the beds upside down over an area of square miles." it is well worth our while to try to understand this statement. our first and most natural inquiry is, what is it that leads scientists to think so? the details of this particular case are not very accessible, and so we are driven to reasoning from analogy from the known methods and constructions employed in this science. we must agree that none of the authorities who report this circumstance can testify as eye-witnesses of this marvellous event: they were not there on the spot when old mother earth turned this huge calcareous and silicious pancake. and yet there must be some kind of evidence by which these eminent men have arrived at this conclusion. what kind of evidence can it be? we cannot imagine any physical evidence which could even remotely suggest such an idea. in fact from the universal custom of making the contained fossils the supreme test of the age of a rock deposit, we are perfectly safe in concluding that it is =solely because the fossils occur here in the reverse of the accepted order=, that we have this astounding picture of an immense mountain mass having been put "upside down over an area of square miles." the "older" fossils are evidently here on top, while the "younger" ones are underneath, and of course some explanation must be given of this flat contradiction of the life succession theory. but let us retrace our steps somewhat, and pick up the thread of our argument. we have already found quite serious reason to question the accuracy of this life succession theory: but there is still another way of testing its rationality. if certain fossils are not necessarily older than certain others, it might reasonably be expected that we would now and then find them reversed as to position, i.e., with the "younger" below and the "older" above. accordingly we have the following very necessary caution from prof. nicholson:[ ] "it may even be said that in any case where there should appear to be a clear and decisive discordance between the physical and the palaeontological (fossil) evidence as to the age of a given series of beds, it is the former that is to be distrusted rather than the latter." to meet all ordinary cases of this character, where the differences involve only a few formations representing a few "ages" or a few million years, the theory of pioneer "colonies" was invented by barrande in . but for extreme cases, say where silurian or cambrian fossils occur =above= jurassic, cretaceous or tertiary, there is in such a predicament always an anxious search made for faults and displacements; or gigantic "thrust-faults" or "overthrust folds," like the example already quoted from dana, are described in picturesque language, many miles in extent--inventions which, as i have already suggested of a similar expedient to explain away evidence, deserve to rank with the famous "epicycles" of ptolemy, and will do so some day. here is geikie's highly instructive statement regarding the same conditions:-- "we may even demonstrate that in some mountainous ground, the strata have been turned completely upside down, _if_ we can show that the fossils in what are now the uppermost layers =ought properly= to lie underneath those in the beds below them."[ ] some day, i fancy, a statement like this will be regarded as a literary curiosity. there are plenty of examples under this head, though two or three ought to be as good as a dozen. in the part of alberta east of the rockies already referred to, is a section of country of about fourteen square miles at least--and we know not how much more--where cambrian fossils are found =above= cretaceous, and the inevitable "thrust fault" is thus described by one of the officers of the canadian geological survey. he has just been speaking of "a series" of these "gigantic thrust faults":-- "one of the largest and most important of these occurs along the eastern base of the chain, and brings the cambrian limestones of the castle mountain group over the cretaceous of the foot hills. this fault has a vertical displacement of more than , feet (? three miles), and an estimated horizontal displacement of the cambrian beds of about seven miles in an easterly section. the actually observed overlap amounts to nearly two miles. the angle of inclination of its plane to the horizon is =very low=, and in consequence of this its outcrop follows a very sinuous line along the base of the mountains, =and acts exactly like the line of contact of two nearly horizontal formations=. "the best places for examining this fault are at the gaps of the bow and of the south fork of the ghost river. at the former place the cretaceous shales form the floor of the bay which the bow has cut in the eastern wall of the range, and rise to a considerable height in the surrounding slopes. their line of contact with the massive gray limestones of the overlying castle mountain group is well seen near the entrance of the gap in the hills to the north. the fault plane here is nearly horizontal, and the two formations, viewed from the valley, =appear to succeed one another conformably=."[ ] but what an amazing condition of affairs is this. here are great mountainous masses of rock, very similar in mechanical and mineral make-up to thousands of examples elsewhere. the line of bedding between them "acts exactly like the line of contact of two nearly horizontal formations," and in a natural section cut out by a river the two "appear to succeed one another conformably." and yet we are asked to believe that all this is merely an optical illusion. the rocks could not possibly have been deposited in this way, for the lower ones contain "benton fossils" (cretaceous), and the upper ones are cambrian, and almost the whole geological series and untold millions of years occurred =after= the upper one, and =before= the lower one was formed. solely on the strength of the infallibility of a theory invented a hundred years ago in a little corner of western europe, which "promulgated, as respecting the world, a scheme collected from that province," and assumed that over all the world the rocks must always follow the order there observed, we are here asked to deny the positive evidence of our senses =because= these rocks do not follow this accepted order. i must confess that i cannot see the force of such a method of reasoning. it is carrying the argument several degrees beyond the reasoning of the three little green peas in the little green pod, as narrated in the exquisite fable of eugene field. these wise little fellows noticed that their little world was all green, and they themselves green likewise, and they shrewdly concluded from this that the whole universe must also be green. but we are not told of their travelling abroad and persisting in a systematic attempt to explain all subsequently observed facts in terms of their theory. this government report last quoted from says that in the eastern part of tennessee the appalachian chain "presents an almost identical structure," and refers to a similar state of things in the highlands of scotland. dana, in the last edition of his "manual" (p. ), refers to this report, and reproduces some of its plates showing some of the structures referred to; and on another page, in speaking of this similar example in scotland, says that "a mass of the oldest crystalline rocks, many miles in length from north to south, was thrust at least ten miles westward over younger rocks, part of the latter fossiliferous"; and further declares that "the thrust planes look like planes of bedding, and were long so considered."[ ] geikie quite naturally devotes several pages in his "text-book" to a description of these conditions in the highlands; but from one of his first reports on these observations, published in _nature_[ ] we get some much more suggestive details. the thrust-planes, he says, are difficult to be "distinguished from ordinary stratification planes, like which they have been plicated, faulted, and denuded. here and there, as a result of denudation, a portion of one of them =appears capping a hill-top=. one almost refuses to believe that the little outlier on the summit does not lie normally on the rocks below it, but on a nearly horizontal fault by which it has been moved into its place." speaking of some similar conditions in ross shire, which he himself had previously described as naturally conformable, he declares:-- "=had these sections been planned for the purpose of deception= they could not have been more skillfully devised ... and no one coming first to this ground would suspect that what appears to be a normal stratigraphical sequence is not really so." "when a geologist finds" things in this condition, he says, "he may be excused if he begins to wonder =whether he himself is not really standing on his head=." but i would only weary the reader by attempting to pursue this subject further. those who wish to do so will find many additional examples in the larger works of dana, leconte, prestwich, and geikie, to say nothing of the more detailed statements buried in numerous government reports and special monographs in german and french. from the very same set of beds different observers try to explain these puzzles in very different ways. some, like helm, will describe gigantic overthrust folds, and will draw immense arcs of circles several miles high in the air, as the place where the rocks must once have been. others, like rothpletz, from an examination of the very same rocks, will cut the mountain up into sections with imaginary fault-planes, and will tell how, in the district about glarus for example, an enormous mass of mountains "travelled from east to west a distance of about twenty-five miles from the rhine valley to the linth," or how the "rhatikon mountain mass travelled from montafon valley to the rhine valley, about nineteen miles from east to west."[ ] with regard to some at least of these conditions in the alps, geikie virtually admits that these incredible and self-contradictory earth-movements are necessitated by and described from fossil evidence only, for he says:-- "... the strata could scarcely be supposed to have been really inverted, save for the evidence (_sic_) as to their true order of succession supplied by their included fossils." "... portions of carboniferous strata appear as if regularly interbedded among jurassic rocks, and indeed could not be separated save after a study of their enclosed organic remains."[ ] in fact, we are perfectly safe in concluding in all similar cases that we may encounter in the literature of the science that it is the reversed order of the fossils which constitutes the whole evidence; for, as i have said, we can imagine no possible physical evidence competent to form a foundation for such ideas, nor do i know of anything save the exigencies of this venerable theory of life succession, for which otherwise competent observers will thus freely sacrifice their common sense. when the dividing line between two sets of strata "acts exactly like the line of contact between two nearly horizontal formations," so much so that in a natural section cut out by a river the two "appear to succeed one another conformably," a calm judicial mind, divested of all theoretical prejudice, instead of talking about these conditions having been planned by nature "for the purpose of deception," will find no difficulty at all in believing that these rocks were really laid down in the =reverse order= in which we now find them, with the "younger" below and the "older" above, and only one under the hypnotic spell of a preconceived theory would at the suggestion of such a fact begin "to wonder whether he himself is not really standing on his head." footnotes: [ ] "manual," p. . [ ] "ancient life-history of the earth," p. . [ ] "text-book," p. , ed. of . [ ] "annual report," new series, vol. ii., part d, pp. - . [ ] pp. , . [ ] nov. , , pp. - . [ ] see _nature_, jan. , , p. . [ ] "text-book," p. . chapter vi fact number four there is only one class of agents now working upon the rocks of the globe which have been in business continuously ever since the dry land appeared, and which have left us a legible record of approximately the amount of business they have been doing all these centuries. and my fact number four, which will complete this line of argument in illustrating the antagonism between the facts of the rocks and the theory of life succession, is that the =rivers= of the world, which of course are the agents to which i have referred, in traveling across the country, =act precisely as if they knew nothing of the varying ages of the rocks=, but on the contrary treat them all alike as if they were of the same age, and =as if they began sawing at them all at the same time=. of course it is, evidently, in only a few cases where the records are so free from ambiguity as to be quite incapable of being misunderstood, that is, the cases of rivers with steep rocky gorges, or those that cut through mountain ranges; but there are several such rivers in the world, and they all seem to tell the same story. the famous colorado river is a good example. it flows from "younger" strata into "older" in its deep cutting across the arizona plateau.[ ] stated in terms of the current theory, this means that when the region of country about the lower part of this river's course first became dry land, the upper part was still sea, and that thus there was no such river in existence here until the very "youngest" of these rocks was formed. for otherwise the river must have started running from the sea toward the dry land, i.e., running up hill. stated in terms neutral as to theory, it means that the whole of this region of country, drained by this large river, with its rocks of many varying "ages," was all elevated practically as it is now before this river began its work of erosion. it treats all these rocks as if they were of the same age, and as if it began sawing at them all at the same time. also its companion, the green river, cuts through the uinta range in the same manner. similar conditions are said to occur on the danube, and in the river-courses of the himalayas, and elsewhere. in the case of the colorado, zittel says that: "powell's explanation of the apparent enigma is that after the river had eroded its channel rocks were uplifted in one portion of its course, but so slow was the rate of uplift that the river was enabled to deepen its channel, either proportionately or more rapidly, so that it was never diverted from its former course." it was by similarly cunning inventions that the early writers on astronomy, alchemy, and medicine evaded the force of accumulated facts which told against their absurd theories. we have now completed our survey of the strictly stratigraphical phases of this question, and have found four very remarkable principles about the rocks, which i wish to summarize here before proceeding further. ( ) the "broad fact," as stated by zittel and dana, that any kind of rocks whatever, i.e. containing any kinds of fossils, even the "youngest," may rest on the archaean, and may thus in position, as also in texture and appearance, resemble the very oldest deposits on the globe. ( ) that any kind of beds may rest in such perfect conformability on any other so-called "older" beds over vast stretches of country that, "were it not for fossil evidence, one would naturally suppose that a single formation was being dealt with," while "the vast interval of time intervening is unrepresented either by deposition or erosion." the youngest seem to have followed the oldest in quick succession. ( ) that in very many cases and over many square miles of country these conditions are exactly reversed, and such very "ancient" rocks as cambrian limestones are on top of the comparatively "young" cretaceous, while the lime between them "acts exactly like the line of contact of two nearly horizontal formations," and in a natural section made by a river the two "appear to succeed one another conformably." to any one ignorant of the theory of life succession they have every appearance of having been deposited as we find them. ( ) that the rivers of the world, in cutting across the country, completely ignore the varying ages of the rocks in the different parts of their courses, and act precisely as if they began sawing at them all at the same time. now i know not what additional fact can be demanded or imagined to complete the demonstration that there is =no particular order= in which the fossils can be said to occur as regards succession in time. it is true, some fossiliferous deposits, metamorphosed almost beyond recognition, and buried deep beneath thousands of feet of subsequent deposits, have enough appearance of remote antiquity about them in all conscience. but to increase this antiquity by saying that other equally prodigious masses of rocks elsewhere were deposited long after these, or by pointing to still other deposits in another region which are said to be older than any of the others, is an illogical and wholly unscientific procedure. i fear i could scarcely confine myself within the bounds of parliamentary language were i to attempt to express an opinion regarding any effort that may now be made to justify the life succession theory in view of the above acknowledged facts. and surely it is scarcely necessary in this enlightened age to point out how completely this vitiates any biological argument (such as that of darwinism) which has incorporated into its system the results of such illogical reasoning, or which in any way is dependent upon the conclusions of such a theory of geology. in view of the laws of evidence, which every intelligent person is supposed to understand now-a-days, surely some strange things passed for scientific proof during the nineteenth century. for, as we have seen, the earlier geologists did little better than =assume= the succession of life bodily; than agassiz and his contemporaries =arranged the details= and the exact order of these successive life forms by comparison with the embryonic life of the modern individual; and now the evolutionists of our day, led by such men as spencer and haeckel with their "phylogenetic principle," =prove their theory of evolution= by showing that the embryonic life of the modern individual is only "a brief recapitulation, as it were, from memory," of the (assumed) geological succession in time. surely this will some day make a more amazing record for posterity than those of phlogiston or the epicycles of ptolemy. if i am now asked: what do the rocks have to tell us, in view of the fact that they refuse to testify to a life succession? i can only say that we are not as yet in a position to decide this question. there are several other matters connected with the character and mode of occurrence of the fossils, which are almost equally important with anything already considered, in forming a true scientific induction regarding this matter. these facts must be considered in subsequent chapters. already, however, we can say this much, that we have in the rocks almost as complete a world, in some respects vastly more complete, than the living world of to-day. with the life succession theory repudiated, we have still to deal with the fossils themselves which have been thus systematically classified; =but this geological series becomes only the taxonomic or classification series of an older state of our present world=, buried somehow and at some time or times in the remote past--the how and the when of which we have not as yet the means to determine. but i think we are now prepared to enter the mazes of the biological argument, and to study the subject of extinct species, which by many is supposed to furnish a line of independent evidence in favor of the life succession theory. footnote: [ ] see zittel, "history of geol.," pp. , . chapter vii extinct species let us now test the value of this assumed life succession by another very simple question. in "eocene times," so we are told, england was a land of palms, with a semi-tropical flora and fauna. in fact at this time, cycads, gourds, proteads (like the australian shrubs and trees), the fig, cinnamon, screw-pine, and various species of acacias and palms, abounded in england and western europe; while turtles, monkeys, crocodiles, and other sub-tropical and warm-temperate forms were equally abundant. then again, in the pleistocene deposits of the same countries, we find various species of elephant and rhinoceros, with a hippopotamus, lion, and hyena, identical with species now living in the tropics, "although," as dana says, "these modern kinds are dwarfs in comparison." =now, how are we to prove that these various forms of animal life did not exist together in these countries at the same time as the trees and plants before mentioned?= lions and monkeys, hippopotami and crocodiles, with elephants, hyenas, and rhinoceroses, now live beneath the palms, mimosas, acacias, and other tropical plants represented in the eocene and miocene beds. what is there to hinder us from believing that they all lived there together in that olden time? surely it would be the very irony of scientific fate if forms now so closely connected in life should in death be so divided. or, to present it in another form, why should we be asked to believe that these acacias, cinnamons, palms, etc., lived and died ages or millions of years before the lions, elephants, rhinoceroses and hippopotami, came into existence to enjoy their shade; and then, after these unnumbered ages had dragged their slow length along and vanished into the dim past, and all these semi-tropical plants had shifted to the tropics or been turned into lignite, these lions, elephants, and hippopotami came into existence in these same localities, when no such plants existed anywhere in europe? surely we ought to expect some pretty substantial evidence for such a violation of "the observed uniformity of nature." we generally boast that we have outgrown the crude ideas of the earlier years of the science when they spoke of "ages" of limestone making or of sandstone making; but it seems that some of us have not yet attained to that broad view of the essential =unity of nature= in which the flora and fauna of our world are seen to be just as indissolubly connected with each other. but nature could as easily be persuaded to produce for a whole age nothing in the way of rock but limestone or conglomerate, as to adjust her powers to such an unbalanced state of affairs as is spoken of above, with the animals in one age and the complementary plants in another. but in considering this question as to why the eocene plants and the pleistocene animals may not be supposed to have lived contemporaneously together, we are brought face to face with the =second= supposed argument in favor of there having been a succession of life on the globe. the answer given is that all the animals of these "early" tertiary beds are extinct species, also very many of the plants; while the hyena, lion, hippopotamus, etc., of the pleistocene are identical with the living species, and even the mammoth is so closely like its nearest surviving relative, the asiatic elephant (_e. indicus_), that these also might be classed as identical.[ ] this point being considered by many as so important, and having such a vital connection with the whole life succession theory, we must go into the matter somewhat in detail, even at the risk of appearing rather technical to some. if the palaeozoic and mesozoic strata are often of enormous extent, spreading in vast sheets over wide regions, so that their stratigraphical order in any particular district is quite readily made out, it is in =most cases= altogether different with the tertiary and pleistocene deposits. for these resemble one another so much in everything except their fossils, and occur so generally in detached and fragmentary beds, holding no stratigraphical relation to one another, that lyell devised the plan of distinguishing them from one another and arranging them in the accustomed order of successive ages, by their relative percentages of living and extinct mollusca. with only unimportant changes, lyell's divisions are still followed in classifying off the tertiary and post-tertiary beds. those with all the species extinct, or less than per cent. living, are classed as eocene; those containing =few= extinct forms, or nearly all living species, are classed as pleistocene or post-tertiary. the miocene and pliocene represent the intermediate grades, and all are supposed to be a true chronological order. it goes without saying that in actual practice it is often so extremely difficult to adjust these differences that beds are assigned to an "early" or a "late" division on =general principles= by what the literary critics would call "tact" or "intuition," rather than by the strict percentage system, though for these large and important divisions of tertiary and post-tertiary rocks, these are absolutely the only professed grounds on which the subdivisions are distinguished and arranged in the customary order of time. in the words of dr. david page: "as there is often no perceptible mineral distinction between many clays, sands and gravels, it is only by their imbedded fossils that geologists can determine their tertiary or post-tertiary character."[ ] now to say that a set of beds, ninety-five per cent. of whose fossils belong to extinct species, and only five per cent. are now living, must be vastly older than another set where these percentages are reversed, i.e. where the species are nearly all living, seems at first thought an eminently reasonable idea, and we immediately begin to imagine the long ages it must have taken for these exceedingly numerous and apparently vigorous species to wear out and become extinct in the alleged ordinary way by the merciless struggle for existence with forms more fitted to survive. but it is hardly necessary to point out that all this is based on the assumption of =uniformity= in its most extreme type, a doctrine which not only denies that these living forms are merely the =lucky survivors= of tremendous changes in which their contemporaries perished, but which in essence is taking for granted beforehand the very point which ought to be the chief aim of all geological inquiry, viz., how did the geological changes take place? it would not be considered a very scientific procedure for a coroner, called upon to hold a _post mortem_, to content himself with interesting statistics about the percentage of people who die of old age, fever, and other causes, while there was clear and decisive evidence that the poor fellow had been =shot=. in this case, as in geology, it is not merely the result that is wrong, but the whole method of investigation. for, as in the latter case we don't want to know how people generally die, but how this particular person actually did die, so, in our study of geology, we do not wish to know merely the rate at which changes of surface and extinctions of species are now going on, and then project this measure backward into the past as an infallible guide, but we wish to know for sure just what changes of this nature have taken place. a true induction is, i think, capable of deciding very positively whether or not the tools of nature have always worked at the same rate and with the same force as at present; and this method of arranging the fossils in supposed chronological order on the percentage basis mentioned above, is only an extreme form of methods claiming to be inductive which in this age of the world ought to be considered a shame and a disgrace, because, as howorth says, they are based, "not upon induction, but upon hypotheses," and have "all the infirmity of the science of the middle ages." then again, it occurs to us, that this method, of attaching a time-value to percentages of extinct or living species, would make the sub-fossil remains of the bison on the western prairies almost infinitely =older= than those of the lion, hippopotamus, etc., in the pleistocene beds of europe; for (except for some few specimens artificially preserved, and which may be ignored in this connection) the bison is to-day absolutely extinct, while the pleistocene mammals are found by the thousand in the proper localities and show no signs of surrender in the struggle for existence. similar comparisons might be made between the great wingless birds of madagascar, mauritius and new zealand, and the many cases of "persistent" forms which have survived unchanged from carboniferous, silurian, or cambrian times, a period of time which, in the language of the current geology, means quite a large fraction of eternity. but all of these considerations show that the mere fact of certain species being extinct and others being now alive, is no trustworthy guide in determining the relative age of their remains, until we first find out =how they happened to become extinct=. the inquiry as to the =how= and the =when= (relatively) is an absolutely essential preliminary in any such investigation; and is inseparably united in nature with the general question of how the great geological changes have taken place in the past. of course, if everything like a world-catastrophe is =a priori= denied; if, in other words, it is settled from the first that all these fossils living and extinct did not live contemporaneously with each other, the living ones being simply the lucky survivors of stupendous changes in which the others perished, then all pretense of a scientific investigation of the subject is at an end. if a coroner has it settled beforehand that an accident or a murder could not possibly have occurred, then his profession of a candid _post mortem_ examination is only a farce; for he does not hold it to find out anything, since he knows everything essential about it beforehand. uniformitarians would certainly make poor coroners, or for that matter poor investigators of law or history, or anything else. will some one please give us a reasonable explanation of why the lion, hippopotamus, rhinoceros, and elephant shifted from england to the tropics? or will they explain how, at this same general time, some elephants and rhinoceroses got caught in the merciless frosts of northern siberia so suddenly that their flesh has remained untainted all these centuries, and is now, wherever exposed, greedily devoured by the dogs and wolves? an abundant warm-climate vegetation once mantled all the polar regions, and its fossils have been found just about as far north as explorers have ever gone; while dana says that, "the encasing in ice of huge elephants, and the perfect preservation of the flesh, shows that the cold finally became =suddenly= extreme, as of a single winter's night, and knew no relenting afterwards."[ ] now, if no one can deny this =sudden= change of climate over half the world or so at least, is it not extremely unscientific to deny that this same cause, whatever it may have been, was quite competent to bring about a good many other changes, and the extinction of numerous other species which we are so often reminded must imply the lapse of untold ages of time? the economizing of energy, or the famous law of parsimony as stated by leibnitz, is quite appropriate in this case, and may be referred to again in the sequel. the principle upon which i must here insist is that the mere fact of certain species being extinct, and others being now alive, gives no clue whatever to the relative age of these remains, until we first ascertain =why=, =how= and =when= this extinction was brought about. and yet, though every one admits the fact of tremendous changes of climate, etc., having intervened between that ancient world and our own (the true extent and character of which, as i have said, ought to be the chief point of all geological investigation), no allowance seems ever to be made for this as a powerful cause of extermination of all forms of life. but in the utter absence of any such explanation as to =how= and =when=, and in the very teeth of these facts assuming a dead-level uniformitarianism, the presence of ten, fifty or a hundred per cent. of extinct forms in a set of beds is manifestly of no scientific value in determining age. it would be many degrees more reasonable and accurate to arrange all the greek and latin books of the world in chronological order according to the percentage of their =words= which have survived into the english language. indeed, it would be much like a coroner, at the inquest following a railway disaster, attempting to arrange the exact order in which the various victims had perished by the proportionate number of surviving relatives which each had left behind him. and the completely worthless character of such "evidence" of age becomes, if possible, more apparent when we consider that very many of these so-called "extinct" forms are not really distinct species from their living representatives of to-day. "it is notorious," says darwin, "on what excessively slight differences many palaeontologists have founded their species." and even to-day, in spite of all that we have learned about variation, little or no allowance seems ever to be made for the effects of a certainly greatly changed environment. if the fossil forms among the mollusks and other shell fish for instance, are not precisely like the modern ones in every respect, they are always classed as separate species, the older forms thus being "extinct," in utter disregard of the striking anatomical differences between the huge pleistocene mammals and their dwarfish descendants of to-day, which for a hundred years or so were declared positively to be distinct from one another, but are now acknowledged to be identical. of course no one denies that there are numerous extinct forms among the invertebrates, just as we know there are among the huge vertebrates of the mesozoic and tertiaries, none of which we moderns have ever seen alive. other forms do not appear familiar to our modern eyes, because larger or of somewhat different form; but to say that they are really distinct species from their modern representatives, or to say that no human being ever saw them alive, are statements utterly incapable of proof. up to about the year it was stoutly maintained that man had never seen =any= of these fossil forms in life. but no one now maintains this view, for human remains have now been found along with undisturbed fossils of the pleistocene, or even middle tertiaries, while the paintings on the cave walls of southern france seem conclusive that they were copied from life when the mammoth and reindeer lived side by side with man in that latitude. hence the only question now is, and it is the supreme question of all modern geology, =with how much of that ancient fossil world were these equally fossil men acquainted?= if man lived in "pliocene" or perhaps "miocene times," when a luxuriant vegetation was spread out over all the arctic regions, what possible evidence is there to show that his companions, the rhinoceros, hippopotamus, mammoth, etc., were not also living then and browsing off just such plants, when the arctic frosts caught them in the grip of death and put their "mummies" in cold storage for our astonishment and scientific information? things which are equal to the same thing are equal to each other; why should not the plants and animals, contemporary with the same creature (man), be just as truly contemporary with one another? if man was contemporary with the miocene plants, and the pleistocene mammals were contemporary with man, what is there to forbid the idea that the pleistocene mammals and the middle tertiary flora were contemporary with each other? for nearly half a century geologists have never had the courage to face this problem fairly and squarely, with all preconceived prejudices about uniformity cast aside. is it possible that all the plants and animals of the tertiaries and the pleistocene may have really lived together in the same world after all? but the trouble would then be that, with this much conceded, the whole "phylogenic series" would tumble with it, and become only the taxonomic or classification series of that ancient world with which these fossil men were acquainted. to appropriate the words of one who has done much to clear the ground for a common-sense study of geology, i know of nothing against such an idea save "the almost pathetic devotion of a large school of thinkers to the religion founded by hutton, whose high priest was lyell, and which in essence is based on _a priori_ arguments like those which dominated mediaeval scholasticism and made it so barren."[ ] baron cuvier's work in the line of comparative osteology has never been surpassed, perhaps never equalled since, and he is said to have been "the greatest naturalist and comparative anatomist of that, or perhaps of any time." (leconte, "evol. and rel. thought," pp. , ); and yet he maintained till the last that all those which we now call the pleistocene mammals were distinct species from the modern ones; and it is only of recent years and with extreme reluctance that many of them have been admitted to be identical with the ones now living. all of which tends to show how unreliable are those assertions commonly found in the text-books about all the species of the so-called "older" rocks being extinct. it is only with hesitation that such specific distinctions are surrendered even to-day, though during the last few decades a steady progress has been made in bringing the palaeontology of the higher vertebrates into line with our increased knowledge of zoology, thus breaking down many of the specific distinctions which have long been maintained between the fossil and the living forms. even the mammoth has been found to have so many characters identical with the modern elephant of india, and such a complete gradation exists between the two types, that flower and lydekker acknowledge the transition from one to the other is "almost imperceptible," and express a doubt whether they "can be specifically distinguished" from one another.[ ] but the extreme reluctance with which anything like a confession of this fact leaks out in our modern literature can be readily understood when we try the hopeless task of splicing the environment of the modern form with that of the ancient on any basis of uniformity. zittel gives us a peep behind the scenes which helps us to appreciate the value of a percentage of extinct species as a test of the age of a rock deposit. he pictures the uncritical work of the earlier writers on fossil botany, until august schink ( - ) made a great reform in this science; and zittel declares that "now the author of a paper on any department" of fossil botany "is expected to have a sound knowledge" of the systematic botany of recent forms. but he adds: "it cannot be said that palaeozoology (the science of fossil animals) has yet arrived at this desirable standpoint." but he justifies this charge of want of confidence by saying: "comparatively few individuals have such a thorough grasp of zoological and geological knowledge as to enable them to treat palaeontological researches worthily, and there has accumulated a dead weight of stratigraphical-palaeontological literature wherein the fossil remains of animals are named and pigeon-holed solely as an additional ticket of the age of a rock-deposit, with a willful disregard of the much more difficult problem of their relationships in the long chain of existence. "the terminology which has been introduced in the innumerable monographs of special fossil faunas in the majority of cases makes only the slenderest pretext of any connection with recent systematic zoology; if there is a difficulty, then stratigraphical arguments are made the basis of a solution. zoological students are, as a rule, too actively engaged and keenly interested in building up new observations to attempt to spell through the arbitrary palaeontological conclusions arrived at by many stratigraphers, or to revise their labors from a zoological point of view."[ ] doubtless this scathing impeachment of the common mania for creating new names for the fossils has especial reference to the case of the lower forms of life. for if, in spite of the brilliant and withal careful work of cuvier, owen, wallace, huxley, ray lankester, and leith adams, with numerous others that might be mentioned, there are still grounds for such grave doubts of the values of specific distinctions in the case of the mammals, whose general anatomy and life-history are so well known and their almost countless variations so well studied out, =what must be the confusion and inaccuracy= in the case of the lower vertebrates, and especially of the invertebrates, whose general life-history in so many instances is so dimly understood, and the limits of their variations absolutely unknown? remembering all this, what is our amazement when we read in this same volume by professor zittel[ ] that the tendency among many modern writers in dealing with these lower forms of life, is toward the erection of the closest possible distinctions between genera and species, until recent palaeontological literature is fairly inundated with new names; and all this with =the purpose=, unblushingly avowed, of "enhancing the value" of such distinctions as a means of determining the relative ages of strata, and to "bring the ontogenetic and phylogenetic development" of the various forms "into more =apparent= correspondence." i do not exaggerate in the least, as the reader may see by referring to zittel's book; though not wishing to make my readers "spell through" another quite technical paragraph i have refrained from direct quotation. but surely we have here a most amazing style of reasoning. it is another clear case of first assuming one's premises, and then proving them by means of one's conclusion. the method here employed seems about like this: first assume the succession of life from the low to the high as a whole; then in any particular group, as of brachiopods or mollusks, decide the momentous question as to which came first and which later in "geological time" by comparing them as to size, shape, etc., with the live modern individual in its development from the egg to maturity; and lastly, =take the results= of this alleged chronological arrangement to prove just =how= the modern forms have evolved. surely it is a most fearful example of otherwise intelligent men being hypnotized by their theory into blind obedience to its suggestions and necessities. not long ago i had occasion to write to a well-known geologist about a lower cambrian mollusk which appears strikingly like a modern species. i give below an extract from his reply which bears directly upon this point. i withhold the name, for the information was given in a half-confidential manner, but i may say that the author's work on the palaeozoic fossils is recognized on both sides of the atlantic. "some geologists make it a point to =give a new name= to all forms found in the palaeozoic rocks, i.e. a name different from those of modern species. i was taken to task by a noted palaeontologist for finding a pupa (a kind of land snail) in devonian beds; but i could not find any point in which it differed from the modern genus [? species]. yet if i could have had more perfect specimens i might have found differences." such disclosures speak volumes for those able to understand; and lead one to receive with a smile the familiar assertion that all the species of the palaeozoic and other "older" rocks are extinct. and we can now form a truer estimate of the high scientific accuracy of lyell's ingenious division of the tertiary beds, according to the percentage of living or extinct mollusks which they contain. but from the inherent weakness of the argument about extinct species as thus revealed, it follows that chronological distinctions based on any proportionate number of extinct species =have absolutely no scientific value=; and hence that the life succession theory finds no support from these chronological distinctions, just as we have already seen that it is without a vestige of support from the stratigraphical argument. the life succession theory has not a single fact to confirm it in the realm of nature. it is not the result of scientific research, but purely the product of the imagination. footnotes: [ ] see p. of this volume. [ ] "intro. text-book," p. . [ ] "manual," p. . prof. dana has italicized the word "=suddenly=." [ ] howorth, "the glacial nightmare and the flood," preface, xx, xxi. [ ] "mammals, living and extinct," pp. - . [ ] "hist. of geol.," pp. - . [ ] pp. , , . chapter viii skipping we have now to deal with another absurdity involved in the life succession theory, the discussion of which grows naturally out of the subject of extinct species. as preliminary to the subject here to be presented, we must bear in mind that the present arrangement of the fossils in alleged chronological order, as well as the naming of thousands of typical specimens, was all well advanced while as yet little or nothing was known of the contents of the depths of the ocean, or even of the land forms of africa, australia, and other foreign countries. in most of the important groups of both plants and animals, the detailed knowledge of the fossil forms preceded the knowledge of the corresponding living forms, just as zittel says that the theories of the igneous origin of the crystalline rocks "had been laid without the assistance of chemistry" and the knowledge of the microscopic structure of these rocks.[ ] on pp. - of his "history," this author shows how, up to , little or nothing of a scientific character was known of any of the classes of living animals save mammals. during the last half century, however, the progress of science has been steadily showing case after case where families and genera, long boldly said to have been "extinct" since "palaeozoic time," are found in thriving abundance and in little altered condition in unsuspected places all over the world. and the point for consideration here is the manifest absurdity of these inhabitants of the modern seas and the modern land =skipping= all the uncounted millions of years from "palaeozoic times" down to the "recent," for, though found in profuse abundance in these "older" rocks, not a trace of many of them is to be found in all the "subsequent" deposits. the proposition here to be considered and proved i shall venture to formulate as follows: =there is a fossil world, and there is a modern living world; the two resembling one another in various details as well as in a general way; but to get the ancestral representatives of many modern types, e.g., countless invertebrates, with other lower forms of animals and plants, we must go clear back to the mesozoic or the palaeozoic rocks, for they are not found in any of the "more recent" deposits.= i have already remarked that the blending of the doctrine of life succession with that of uniformity, must inevitably have given birth to the evolution theory, for it is evident that the succession from the low to the high could only have taken place by each type blending with those before and those after it in the alleged order of time. that such is not the testimony of the rocks, even when arranged with this idea in view, is too notorious to need any words of mine, for it has been considered by many[ ] the "greatest of all objections" to the theory of evolution. this abruptness in the disappearance of "old" and the first appearance of "new" forms, has brought into being that "geological scape-goat," as james geikie has called the doctrine of the =imperfection of the record=. but dawson has well disposed of this argument in the following words: "when we find abundance of examples of the young and old of many fossil species, and can trace them through their ordinary embryonic development, why should we not find examples of the links which bound the species together?"[ ] but it is equally evident that each successive series ought to contain, in addition to its own characteristic or "new" species, =all the older forms which survived into any later deposits, or are now to be found living in our modern world=. such no doubt was the idea of those of the early geological explorers who discarded werner's onion-coat theory, and they tried to arrange their series accordingly. this reasonable demand is still recognized as good; and the principle is alluded to by dana when he attempts to show how strata might be discovered and "proved" to be older than the present lower cambrian rocks.[ ] it is, i say, still recognized =in theory= that the "younger" deposits ought to contain samples of the "older" types which were still surviving, in addition to their own characteristic species; but with the progress of geological discovery it has long since been found that such an arrangement was utterly impossible. indeed, it would almost seem as if modern writers had forgotten the principle altogether. for, as already said, according to the present chronological arrangement, many kinds of invertebrates, both terrestrial and marine, occurring in comparative abundance in our modern world, are found as fossils only in the very "oldest" rocks and are =wholly absent from all the rest!!!= others which date from "mesozoic times" are wholly absent from the tertiaries, though abundant in our modern world. this i regard as another crucial test of the rationality of this idea of a life succession. of course there are certain limitations which must be borne in mind. if we find a series of beds made up largely of deep sea deposits, we cannot reasonably expect to find in them examples of all the land forms of the preceding "ages" which then survived, nor even of the shallow water types. nor, conversely, can we demand that, in beds crowded with the remains of the great mammals and plants, and thus probably of fresh or shallow water formation, we ought to find examples of all the marine types still surviving. we now know that each level of ocean depth has its characteristic types of life, just as do the different heights on a mountain side. this doctrine of "rock facies" was, i believe, enunciated first in . edward forbes also did much for this same idea, showing how at the present time certain faunas are confined to definite geographical limits, and particular ocean depths. jules marcou about applied this principle to the fossils and showed how such distinctions must have prevailed during geological time. here it seems that we are at last getting a refreshing breath of true science; but if carried out in its entirety how shall we assure ourselves that in the long ago very diverse types of fossils, e.g., gratolites and nummulites, or even trilobites and mammals, =could not have been contemporary with each other=? this principle of "rock facies," if incorporated into the science in its early days, would have saved the world from a large share of the nonsense in our modern geological and zoological text-books. but in answer to any pleadings about the imperfection of the record, or any protests about the injustice of judging all the life-forms of an "age" by a few examples of local character, i.e., of fresh, shallow, or deep water as the case may be, the very obvious retort is, why then are such local and fragmentary records given =a time value=? why, for example, should the carboniferous and associated formations be counted as representing all the deposits made in a certain age of the world, when we know from the cambrian and silurian and also from the alleged "subsequent" jurassic that there must have been vast open sea deposits formed contemporaneously? as dana expresses it: "the lias and oolyte of britain and europe afforded the first full display of the marine fauna of the world since the era of the subcarboniferous. very partial exhibits were made by the few marine beds of the coal measures: still less by the beds of the permian, and far less by the triassic. the seas had not been depopulated. the occurrence of over , invertebrate species in britain in the single jurassic period is evidence, not of deficient life for the eras preceding, but of extremely deficient records."[ ] surely these words exhibit the "phylogenic series" in all its native, unscientific deformity. it is =because= the coal-measures, the permian, and the triassic, are necessarily "extremely deficient records" of the total life-forms then in the world, that i am writing this chapter, and this book. but it seems like perverseness to plead about the imperfection of the record, and yet refuse the =evidently complementary= deposits when they are presented. if, as this illustrious author says, "the seas had not been depopulated," what would he have us think they were doing? were they forming no deposits all these intervening ages that the carboniferous, permian, and triassic were being piled up? were the fishes and invertebrates all immortalized for these ages, or were they, when old and full of days translated to some supermundane sphere, thus escaping deposit in the rocks? did the elements continue in the _status quo_ all these uncounted millions of years? and if so, how did they receive notice that the triassic period was at last ended, and that it was time for them to begin work again? i do not like to appear trivial; but these questions serve to expose the folly of taking diverse, local, and partial deposits, and attaching a chronological value to each of them separately, and then pleading in a piteous, helpless way about the imperfection of the record. and yet i cannot promise to present a tithe of the possible evidence, because of two serious handicaps. first, the ordinary literature of the science is silent and meagre enough in all conscience, even though the bare fact may be recorded that a "genus" of the cambrian or silurian is "closely allied" to some genus now living. it may be even admitted that "according to some it is not genetically distinct from the modern genus" so-and-so; but the authors =never descend below the "genus,"= and in most cases forget to tell us whether or not it occurs in other "later" formations, though of course the presumption is that it does not, but has skipped all the intervening ages, or it would hardly be named as a characteristic type of the formation in which it occurs. but this disadvantage, serious though it be, is scarcely worth speaking of when we remember the significant words of a well-known authority already quoted: "some geologists make it a point to give a new name to all forms found in the palaeozoic rocks, i.e. a name different from those of modern species." or zittel's confession that: "the terminology which has been introduced in the innumerable monographs of special fossil faunas in the majority of cases makes only the slenderest pretext of any connection with recent systematic zoology; if there is a difficulty, then stratigraphical arguments are made the basis of a solution. zoological students are as a rule too actively engaged and keenly interested in building up new observations to attempt to spell through the arbitrary palaeontological conclusions arrived at by many stratigraphers, or to revise their labors from a zoological point of view." hence i have no reluctance in saying that, in the present confused state of the science, it is utterly impossible to find out the truth as to how many hundreds of these "genera" of the paleozoic rocks may have survived to the present, though having skipped perhaps all the formations of the intervening millions of years. i doubt not that the number is enormously large, though as i have not attempted "to spell through the arbitrary palaeontological conclusions" scattered through the literature, i can only depend on a few though striking examples that lie on the open pages of the ordinary text-books. the larger mammals can of course furnish us no examples, for the "age" in which they abounded is quite conveniently modern, and is separated from the present by no great lapse of time. of the smaller marsupials, quite a number of jaw-bones have been found in the jurassic and triassic, one from the latter being strikingly like the living _myrmecobius_ of australia. they are scarcely more numerous in the cretaceous of america, while in the foreign rocks of this system dana says that "only one species had been reported up to ." those strange, sad-eyed creatures called lemurs deserve a passing notice, for though now confined as to their typical forms to the island of madagascar, their fossils seem as exclusively confined to the temperate regions of the new and the old world. flower and lydekker enumerate about fifteen fossil species, and add that: "... it is very noteworthy that all these types seem to have disappeared from both regions with the close of the upper portion of the eocene period."[ ] but this jump from the "eocene period" to the present is as nothing compared with the secular acrobatics of some of the fishes and especially of the invertebrates. the living cestraciont sharks, of which there are four species found in the seas between japan and australia, seem to disappear with the cretaceous, skipping the whole tertiary epoch, as do also a tribe of modern barnacles which, as darwin says, "coat the rocks all over the world in infinite numbers." the dipnoans or lung-fishes (having lungs as well as gills, such as the _ceratodus_ and _lepidosiren_), which are represented by several living species in australia and south africa, are the remains of a tribe found in whole shoals in the carboniferous, triassic and jurassic rocks, but not, so far as i know, in any of the intervening rocks. the living ceratodus was only discovered in , and was regarded as a marvel of "persistence." on a pinch, as when his native streams dry up, this curious fellow can get along all right without water, breathing air by his lungs like a land animal. if in the meantime he was off on a trip to the moon, he must have "persisted" a few million years without either. but his cousin, the _polypterus_ of the upper nile, has a still more amazing record, for he has actually skipped all the formations from the devonian down to the modern; while the limuloids or sea scorpions have jumped from the carboniferous down. the mollusks and brachiopods would afford us examples too numerous to mention. how is it possible that these numerous families disappear suddenly and completely with the mesozoic or even the "early" palaeozoic, and are not found in any "later" deposits, though alive now in our modern world? parts of europe and america have, we are told, been down under the sea and up again a dozen times since then; why then should we not expect to find abundant remains of these "persistent" types in the mesozoic and tertiaries? surely these feats of time-acrobatics show the folly of arranging contemporaneous, taxonomic groups in single file and giving to each a time value. the chalk points a similar lesson. it was not till the time of the "challenger" expedition that the modern deposits of globigerina ooze, made up of species identical with those of the chalk, were known to be now forming over vast areas of the ocean floor. in the words of huxley, these modern species "bridge over the interval between the present and the mesozoic periods."[ ] as for the silicious sponges found in the chalk, which were such puzzles for the scientists during the first half of the nineteenth century, because their living forms were unknown, the deep-sea investigations have solved the problem, for in sollas demonstrated "the identity of their structure with that of living hexactinellids, lithistids, and monactinellids."[ ] and yet with all the alleged vicissitudes of the continents during the millions of years since the cretaceous age, there is so far as i am aware not a trace of either the chalk or the sponges in any of the "subsequent" rocks. pieces of cretaceous rock are of course found thus sporadically as boulders, but there is no natural deposit of this kind. but in the light of these modern discoveries why is not the chalk of "the white dear cliffs of dover," full of modern living species as we now know it to be, just as "recent" a deposit as the "late" tertiaries or the pleistocene? another good illustration of the absurdity of the present arrangement of the rocks is found in the echinoderms--crinoids, star-fishes, sea-urchins, etc. of the latter prof. a. agassiz found in the deep waters of the west indies, four genera of echinids or sea-urchins of the "later tertiary," =but genera of the "early" tertiary, of the cretaceous, and of the jurassic=.[ ] but far from being uncommon we know that similar discoveries have been in almost constant progress during the last half century. and were it not that "zoological students are," as zittel says, "too actively engaged and keenly interested in building up new observations to attempt to spell through the arbitrary palaeontological conclusions" found in the "dead weight of stratigraphical-palaeontological literature," there is no telling what hosts of similar facts might not be pointed to regarding the forms found in all the "older" rocks. of the star-fishes and serpent-stars (_asteridea_ and _ophiuridea_), zittel says: "it would seem that the palaeozoic 'sea-stars' differed very little from those in the seas of the present age." (p. .) the crinoids, we are told, "are among the earliest in geological history," making up vast limestones of the palaeozoic rocks; and forms scarcely separable from the modern are found in the jurassic, but so far as the text-books tell us are =absolutely unknown in any later deposits=. but there are several modern genera, such as pentacrinus, rhizocrinus, bathycrinus, etc., found in the deep waters of nearly all the oceans. the genus rhizocrinus was discovered off the coast of norway about the sixties of the last century. but what were these creatures doing since "jurassic times," while the "pulsating crust" was putting parts of the continents under the sea for ages at a stretch? why did they form no deposits during the cretaceous, eocene, miocene or pliocene ages? surely the absurdity of the present arrangement is evident to a child. during all these intervening ages the climate of the globe continued of the same remarkable mildness, fossils of all these formations being found about as far north as explorers have ever gone. why did the crinoids and polyp-corals suspend business from "jurassic times" to the "recent," merely to accommodate a modern theory? dana says that "the coral reefs of the oolyte in england consist of corals of the same group with the reef-making species of the existing tropics,"[ ] and he argues from this fact that the mean temperature of the waters must have been about deg. f. but a luxuriant vegetation still continued in the arctic regions during the cretaceous and the tertiaries. how absurd to say that these corals built no reefs about the european coasts during all these ages. or, to put the matter in another way, considering how many of their characteristic types are alive in our modern seas, why should we say that the crinoidal or coral limestones of the mesozoic or palaeozoic rocks are not as recent as the nummulitic limestones of the eocene or any late tertiary deposits? it is no answer at all to tell us that, though the general types are the same, the =species= of the palaeozoic and the mesozoic are entirely extinct. i have not had the courage "to attempt to spell through" all the "dead weight" of the modern literature, but i think that the world would like more satisfactory proof of this oft-repeated assertion than the customs and traditions of a hundred years, and the exigencies of a fanciful theory. this worn-out argument of cuvier's about extinct species has kept up a running fight with common sense for many decades, and though driven backward from one point to another over the long thin line of this taxonomic series of the fossil world, it still contests every inch of ground. but let us try the tree-ferns and cycads of the coal beds of the "older" rocks. in northern regions they are not found "later" than the triassic and jurassic, and doubtless the same holds good of the rocks in the tropics, where the modern species now live in fair abundance. but how did they come to shift to the tropics so many millions of years before the palms, etc., of the tertiaries thought it time to do the same? the climate had not changed a bit: how did they come to scent the coming "glacial age" so much earlier than their more highly organized fellows? the "challenger" expedition found some cyathophylloid corals now building reefs at the bottom of our modern ocean. the geologists had already assigned =the last= of them to the carboniferous and permian rocks with the idea that they were extinct. but where have these fellows kept themselves during all the intervening ages while the continents were deep under the ocean time and time again? or why are not the rocks containing their fossils as "recent" as any deposits on the globe? and so i might go on. there is hardly a tribe found in the "older" rocks which does not have its living representatives of to-day, and with, i believe, a fair proportion of the species identical; though in hundreds, perhaps thousands, of cases these species, genera, or even whole tribes, have somehow skipped all the intervening formations. but let us drop this method of studying our subject, and look at it from a slightly different standpoint. thus dana[ ] says that: "the absence of lamellibranchs in the middle cambrian, although present in both lower and upper, means =the absence of fossils from the rocks, not of species from the faunas=." he puts this in italics by way of emphasis, for it is certainly a reasonable idea, and as a. r. wallace says, "no one =now= doubts that where any type appears in two remote periods it must have been in existence during the whole intervening period, although we may have no record of it."[ ] but what would be the result if we only extend this idea to its logical conclusion? it seems to be an effort to avoid one of the absurdities of the onion-coat theory, without, however, discarding that theory altogether. in speaking of some corals and crinoids of the devonian which "were absent" from some of the divisions of this formation because the conditions of the seas about new york "were unfavorable," dana says that "they were back when the seas were again of sufficient purity."[ ] in his review of these formations he enlarges on this subject: "at the close of the early devonian the evidences of clear seas--the corals and crinoids, with most of the attendant life--disappear, migrating no one knows whither.... with the variations in the fineness, or other characteristics of the beds as h. s. williams has illustrated, the species vary.... =the faunas of each stratum are not strictly faunas of epochs or periods of time, but local topographical faunas.= after the corniferous period, corals, crinoids, and trilobites still flourished =somewhere=, as before, but they are absent from the central interior until the carboniferous age[ ] opens." here we are certainly getting a refreshing breath of common-sense geology; but what would become of current theories if we enlarge a little on this idea? what if the gigantic dinosaurs of the cretaceous or the equally marvellous mammals of the "early" tertiaries of the western states, described by marsh and cope, and the pleistocene mammals of other parts of america and of europe and northern siberia, "are not strictly faunas of epochs or periods of time, but local topographical faunas?" what if the world-wide limestones of the cambrian and silurian, and the no less enormous or widespread nummulitic limestones of the eocene, extending from the alps to eastern asia, and constituting mountains ten, fifteen, or twenty thousand feet high--what if these are possibly =contemporaneous with one another=? supposing the coal-measures of nova scotia and pennsylvania, and the cretaceous and tertiary lignites of vancouver island, alberta, and the western states are not strictly floras of epochs or periods of time, but local topographical floras?[ ] but it must be confessed that the logical extension of this broad view of the fossils, and the projection of our modern zoological provinces and zones back into the fossil world would mean the death-blow to the life succession theory, and might have a very disturbing effect upon certain theories about human origins and other genetic relationships which have grown quite popular since the middle of the last century. footnotes: [ ] "history," pp. , . [ ] see leconte, "evol. and religious thought," p. . [ ] "modern ideas of evol.," p. . [ ] see "manual," pp. - . [ ] "manual," p. . [ ] "mammals, etc." p. . [ ] "discourses biol. and geol.," p. . [ ] zittel, "hist. of geo.," p. . [ ] dana, "manual," p. . [ ] "manual," p. . [ ] "manual," p. . [ ] "distribution of life," p. . [ ] "manual," p. . [ ] "manual," pp. - . [ ] note--this is only carrying the argument a little further than huxley does when he says that "a devonian fauna and flora in the british islands may have been contemporaneous with silurian life in north america, and with a carboniferous fauna and flora in africa. geographical provinces and zones may have been as distinctly marked in the palaeozoic epoch as at present." "discourses," p. . part ii. chapter ix graveyards "the crust of our globe," writes a distinguished scientist, "is a great cemetery, where the rocks are tombstones on which the buried dead have written their own epitaphs." the reading of these epitaphs is the business of geology; and too often, as we shall see, the record is that of a violent and sudden death. with the doctrine of uniformity as a theoretical proposition, i shall have little to say. at best it is a pure assumption that the present quiet and regular action of the elements has always prevailed in the past, or that this supposition is sufficient to explain the facts of the rocks. in its more extreme form it becomes an iron dogma, which shuts out all evidence not agreeable to its teachings. but in its essential nature, whether in its least or its most extreme form, it is not approaching the subject from the right standpoint. it seeks to show how the past geological changes may have occurred; it never attempts to prove how they =must= have occurred. and i may say in passing, that it is largely for the purpose of avoiding the cumulative character of the evidence gathered from every stone quarry and from every section of strata in every corner of the globe, that the uniformitarians have wished to have these burials take place on the installment plan; for otherwise the violent and catastrophic character of the events recorded in the rocks would become too plainly manifest. but if a coroner, called upon to hold an inquest, were to content himself, after the manner of lyell and hutton, with glittering generalities about how people are all the time dying of old age, fever, or other causes, coupled with assurances of the quiet, regular habits and good reputation of all his fellow citizens, i do not think that he would be praised for his adherence to inductive methods if we could get at clear and decisive evidence that the poor fellow under examination had been shot. just so with common-sense methods in geology. =a true induction is capable of finding out for certain= whether or not the present quiet regular action of the elements has always prevailed in the past; and it is most unscientific to assume, as the followers of hutton and lyell have done, that the comparatively insignificant changes within historic time have always prevailed in the past, when there is plenty of clear and decisive evidence to the contrary. the general fact which i wish to develop in this chapter may be stated somewhat as follows: =rocks belonging to all the various systems or formations give us fossils in such a state of preservation, and heaped together in such astonishing numbers, that we cannot resist the conviction that the majority of these deposits were formed in some sudden and not modern manner, catastrophic in nature.= but before giving any examples of these abnormal deposits we must first study the modern normal deposits; before we can rightly understand the sharp contrast between the ancient and the modern action of the elements, we must become familiar with the way in which fossils are now being buried by our rivers and oceans. one of the many geological myths dissipated by the work of the "challenger" expedition, which, as zittel says, "marks the grandest scientific event of the nineteenth century," is that about the ocean bottom and the work now being carried on there. the older text-books taught that, not only was the bottom of the ocean thickly strewn with the remains of the animals which died there and in the waters above, but also that the oceanic currents were constantly wearing away in some places and building up in others over all the ocean floor, and hence producing true stratified deposits. accordingly it was said that it was only necessary for these beds to be lifted above the surface to produce the ordinary rocks that we find everywhere about us. but we now know that the ocean currents have, as dana says, "no sensible, mechanical effects, either in the way of transportation or abrasion."[ ] we know also that all kinds of sediment drop so much quicker in salt water than in fresh, that none of it gets beyond the narrow "continental shelf" and the classic fathom line, which in most cases is not very far from shore. in the north atlantic there are sediments found in deeper water produced by ice-floes or icebergs dropping their loads there; but we cannot suppose such work to have gone on when the arctic regions were clothed with a temperate-climate vegetation, much less that such things occurred over all the earth. on the floor of the open ocean, and away from the tracks of our modern icebergs, we have two or three kinds of mud or ooze formed from minute particles of organic matter; but besides these =absolutely nothing= save a possible sprinkling of volcanic products, which of course are limited in their distribution. where then can we find a stratified or bedded structure now being formed over the ocean bottom? dana says there is nothing of the kind now being produced there, save as the result of possible variations during the passing ages in the organic deposits thrown down, where a bed of ooze may be supposed to be thrown down directly upon another kind of ooze. there is =no gravel=, =no sand=, =no clay=, but whatever variation there might be in the organic deposits, the new kind would be laid down immediately upon the preceding similar deposits, unless a thin sprinkling of volcanic dust happened to intervene. thus to explain practically all the deposits found in the rocks, we are absolutely limited to the shore deposits and the mouths of large rivers. here we certainly have alternations of sand, clay and gravel, producing a true bedded structure. but i ask: what kind of organic remains will we get from these modern deposits? certainly nothing like the crowded graveyards which we find everywhere in the ancient ones. darwin, in his famous chapter on "the imperfection of the geological record," has well shown how scanty and imperfect are the modern fossiliferous deposits. the progress of research has only confirmed and accentuated the argument there presented on this point. thus nordenskiold, the veteran arctic explorer, remarks with amazement on the scarcity of recent organic remains in the arctic regions, where such a profusion of animal life exists; while in spite of the great numbers of cats, dogs and other domestic animals which are constantly being thrown into rivers like the hudson or the thames, dredgings about their mouths have revealed the surprising fact that scarcely a trace of any of them is there to be found.[ ] even the fishes themselves stand a very poor chance of being buried intact. as dana[ ] puts it: "vertebrate animals, as fishes, reptiles, etc., which fall to pieces when the animal portion is removed, =require speedy burial after death=, to escape destruction from this source (decomposition and chemical solution from air, rain-water, etc.), as well as from animals that would prey upon them." if a vertebrate fish should die a natural death, which of itself must be a rare occurrence, the carcass would soon be devoured whole or bit by bit by other creatures near by. possibly the lower jaw, or the teeth, spines, etc., in the case of sharks, or a bone or two of the skeleton, might be buried unbroken, but a whole vertebrate fish entombed in a modern deposit is surely a unique occurrence. but every geologist knows that the remains of fishes are, in countless millions of cases, found in a marvelous state of preservation. they have been entombed in =whole shoals=, with the beds containing them miles in extent, and scattered over all the globe. indeed, so accustomed have we grown to this state of affairs in the rocks we hammer up, that if we fail to find such well-preserved remains of vertebrate fishes, land animals, or plants, we feel disappointed, almost hurt; we think that nature has somehow slighted this particular set of beds. but where in our modern quiet earth will we go to find deposits now forming like the copper slate of the mansfield district, the jurassic shales of solenhofen, the calcareous marls of oeningen on lake constance, the black slates of glarus, or the shales of monte bolca?--to mention some cases from the continent of europe more than usually famous in the literature for exquisitely preserved vertebrate fishes, to say nothing of other fossils. according to dana, all these must have met with a "speedy burial after death"--perhaps before, who knows? buckland[ ] in speaking of the fossil fish of monte bolca, which may be taken as typical of all the others, is quite positive that these fish must have "perished suddenly," by some tremendous catastrophe. "the skeletons of these fish," he says, "lie parallel to the laminae of the strata of the calcareous slate; they are always entire, and so closely packed on one another that many individuals are often contained in a single block.... =all these fish must have died suddenly= on this fatal spot, and have been speedily buried in the calcareous sediment then in course of deposition. from the fact that certain individuals have even preserved traces of color upon their skin, we are certain that they were entombed before decomposition of their soft parts had taken place." in many places in america as well as europe, where these remains of fish are found, the shaley rock is so full of fish oil that it will burn almost like coal, while some have even thought that the peculiar deposits like albertite "coal" and some cannel coals were formed from the distillation of the fish oil from the supersaturated rocks. de la beche[ ] was also of the opinion that most of the fossils were buried suddenly and in an abnormal manner. "a very large proportion of them," he says, "must have been =entombed uninjured, and many alive=, or, if not alive, at least before decomposition ensued." in this he is speaking not of the fishes alone but of the fossiliferous deposits in general. there is a series of strata found in all parts of the world which used to be called the "old red sandstone," now known as the devonian. in this, almost wherever we find it, the remains of whole shoals of fishes occur in such profusion and preservation that the "period" is often known as the "age of fishes." dr. david page, after enumerating nearly a dozen genera, says: "these fishes seem to have thronged the waters of the period, and their remains are often found in masses, =as if they had been suddenly entombed in living shoals= by the sediment which now contains them." i beg leave to quote somewhat at length the picturesque language of hugh miller[ ] regarding these rocks as found in scotland. "the river bull-head, when attacked by an enemy, or immediately as it feels the hook in its jaws, erects its two spines at nearly right angles with the plates of the head, as if to render itself as difficult of being swallowed as possible. the attitude is one of danger and alarm; and it is a curious fact, to which i shall afterward have occasion to advert, that =in this attitude nine-tenths of the= _pterichthes_ =of the lower old red sandstone are to be found=.... it presents us, too, with a wonderful record of violent death falling at once, not on a few individuals, but on whole tribes." "at this period of our history, some terrible catastrophe involved in sudden destruction the fish of an area at least a hundred miles from boundary to boundary, perhaps much more. the same platform in orkney as at cromarty is strewed thick with remains, which exhibit unequivocally the marks of violent death. the figures are contorted, contracted, curved, the tail in many instances is bent round to the head; the spines stick out; the fins are spread to the full, as in fish that die in convulsions.... the record is one of destruction at once widely spread and total, so far as it extended.... by what quiet but potent agency of destruction were the innumerable existences of =an area perhaps ten thousand square miles in extent annihilated at once=, and yet the medium in which they had lived left undisturbed in its operations? "conjecture lacks footing in grappling with the enigma, and expatiates in uncertainty over all the known phenomena of death." i shall not taunt the uniformitarians by asking them to direct us to some modern analogies. but i would have the reader remember that these devonian and other rocks are absolutely world-wide in extent. surely howorth is talking good science when he says that his masters sedgwick and murchison taught him "that no plainer witness is to be found of any physical fact than that nature has at times worked with enormous energy and rapidity," and "that the rocky strata teem with evidence of violent and sudden dislocations on a great scale." i have spoken only of the class fishes. but what other class of the animal kingdom will not point us a similar lesson? the reptiles and amphibians, to say nothing of the larger mammals, are also found in countless myriads, packed together as if in natural graveyards. everybody knows of the enormous numbers and splendid preservation of the great reptiles of the western and southern states, untombed by leidy, cope and marsh. one patch of cretaceous strata in england, the wealden, has afforded over thirty different species of dinosaurs, crocodiles, and pleisosaurs. mr. chas. h. sternberg, one of zittel's assistants, recently reported great quantities of amphibians from the permian of texas. they are of all sizes, some frogs being six feet long, others ten. besides these he found three "bone-beds" full of minute forms an inch or less in length. of the small ones, which i judge must represent whole millions of young ones =suddenly= entombed, he says: "i got over twenty perfect skulls, many with vertebrae attached, and thousands of small bones from all parts of the skeleton. in one case, a complete skull, one-fourth of an inch in length, had connected with it nearly the entire vertebral column, with ribs in position, coiled upon itself, bedded with many bones of other species in a red silicious matrix. so perfectly were they weathered out that they lay in bas-relief =as white and perfect as if they had died a month ago=; a single row of teeth, =like the points of cambric needles=, occupied both sets of jaws."[ ] how many more such cases there may have been in these "three bone-beds full" of similar remains, it would be interesting to know. but though somewhat aside from the present subject, i cannot refrain in passing from referring to the wonderful preservation of these remains. it is preposterous to say that these bones have lain thus exposed to the weather for the millions of years postulated by the popular theory. there is not a particle of scientific evidence to prove that they are not just as recent as any specimen from the tertiaries or the pleistocene. buffon and cuvier proved the mammals to be of "recent" age, because they occurred in the superficial deposits. they never heard of the triassic, jurassic, and cretaceous of colorado and wyoming, nor these permian of texas. think of this frog's teeth "like the points of cambric needles," and he and his fellows "as perfect as if they had died a month ago." of one of the big six-foot specimens this author says: "its head was so beautifully preserved, and cleaned under long erosion, it was difficult to believe it was not a recent specimen." while of the little six-inch fellow referred to above he says: "the bones of the skull are perfectly preserved, quite smooth, and show the sutures distinctly; there is no distortion, some red matrix attached below seems absolutely necessary to convince the mind that it is not =a thing of yesterday=." james geikie[ ] mentions the case of the elgin sandstones "formerly classed as 'old red,'" but which are now called triassic, "from the fact that they have yielded reptilian remains of a higher grade than one would expect to meet with in old red sandstone." since these strata =slide up and down so easily=, we have here far more urgent scientific reasons for calling these amphibian remains of texas among the most "recent" geological deposits on the globe. but i must return to my subject. the invertebrates are also eloquent to the fact of abnormal conditions having prevailed when their remains were entombed. we could go through the whole list, but it is the same old story of abnormal deposits, essentially different from anything that is being made to-day. where, for instance, in the modern seas, will we find the remains of polyp-corals now being intercalated between beds of clays or sands over vast areas, as we find them in the lias and oolyte of england and elsewhere? corals require a definite depth of water, neither too deep nor too shallow, but it must be clear and pure; and nothing but some awful catastrophe could place a bed of coral remains a few feet or a =few inches= in thickness over the vast areas that we find them. crinoids require the same clear, pure water, but much deeper, some of the modern kinds living =over a mile down=, but every student of the science knows that the subcarboniferous limestone of both europe and america (called mountain limestone in england), so noted for its crinoids and its corals, is constantly found intercalated between shale or sandstone, or between the coal beds themselves as at springfield, ill., or in the lower coal measures of westmorland county, pa. there are of course, here and there, great masses of these rocks which represent an original formation by growth _in situ_; but no sane man can say this for these great sheets perhaps =only a few inches= in thickness, for in many cases they show a stratified or bedded structure just as much as a sandstone or a shale. in some tables given by dana on pp. - of his "manual," compiled from four different localities, i count no less than = beds= of limestone thus intercalated, though we are not told how many of them contain corals or crinoids. such details are generally omitted as of little consequence. next, let us try the lamellibranchs, such as the clam, oyster, and other true bivalves. these creatures have an arrangement in the hinge region by which the valves of the shell tend to open, but during life are held together by the adductor muscles. when dead, however, these muscles relax and decay, and then the valves spread wide open. of course there are some, such as certain kinds of clams, which burrow in the mud or sand, and the shells of these, if they happened to die a natural death in their holes, could not spread very far apart. however =some mud= must even then wash into their burrows and into their empty shells. but many kinds of bivalves do not thus burrow in the ground; and when the fossils of such kinds are found in quantity with the valves =applied= and often =hollow=, as is so frequently the case in many of the "older" rocks, i cannot see how we are to understand any ordinary conditions of deposit. and yet we are gravely assured by a high authority, that "a sudden burial is not necessary to entombment in this condition." or, let us take the brachiopods. these have a bivalve shell, the parts of which, however, are not pulled apart after death, and only need to open a little way even in life to admit the sea water which brings them their food. yet, though the valves do not gape after death, there is when dead and empty a =hole= at the hinge or beak, which would readily admit mud if such were present in the water, or if the shells after death were subject to the ordinary movements of tide, wave and current. yet dawson[ ] says of the brachiopods, spirifer and athyris: "i may mention here that in all the carboniferous limestones of nova scotia the shells of this family are usually found with the valves closed and =the interior often hollow=." of course he tries to explain how this state of things might occur "in deep and clear water"--for some of the modern species are found in the clear depths , feet down--and he thinks that their entombment in this condition "does not prove that the death of the animals was sudden." but we now know that there is no means of producing a stratified formation in this "deep and clear water," and hence that some revolution of nature is implied by the conditions in which we find them. some people seem to have converted david hume's famous sentence into a scientific formula, thus: "anything contrary to uniformity is impossible: hence no amount of evidence can prove anything contrary to uniformity." for the trouble in this case is that, not only do such conditions prevail "in all the carboniferous limestones of nova scotia," which must be several thousands of square miles in extent, but in the devonian shales and silurian limestones of ontario and the middle states at least--perhaps over the rest of the world--the brachiopods are found =in this same tell-tale condition=, and it would establish a very dangerous precedent to admit abnormal conditions in even a single case. i have only touched upon the voluminous evidence that might be adduced in the case of the lower forms of life. had i the space, i might show how the marvelously preserved plants of the coal beds tell the same story. but we must pass on to consider the remains of the larger land animals. i have already given a quotation from dana about the mammoth and rhinoceros in northern siberia, where he says that their encasing in ice and the perfect preservation of their flesh "shows that the cold finally became =suddenly= extreme, as of a single winter's night, and knew no relenting afterward." not very many serious attempts have been made to account for this remarkable state of things, which is a protest against uniformity that can be appreciated by a child, and i never heard of any theory which attempted to account for the facts without some kind of awful catastrophe. many, however, seem to have little idea of the extent of these remains in the arctic regions. they are not all thus perfectly preserved, for thousands of skeletons are found in localities where the ground thaws out somewhat in the short summer, and here of course, the skin and tissues could not remain intact. remains of these beasts occur in only a little less abundance over all western europe, and the mammoth also in north america, well preserved specimens having been obtained from the klondike region of alaska; and there is nothing to forbid the idea that many, if not most of these latter specimens were also at one time enshrined as "mummies" in the ice, which has since melted over the more temperate regions. but we must confine ourselves to the remains in siberia. flower and lydekker tell us that since the tenth century at least, these remains have been quarried for the sake of the ivory tusks, and a regular trade in this fossil ivory, in a state fit for commercial purposes, has been carried on "both eastward to china, and westward to europe," and that "fossil ivory has its price current as well as wheat." "they are found at all suitable places along the whole line of the shore between the mouth of the obi and behring straits, and the further north the more numerous do they become, the islands of new siberia being now one of the favorite collecting localities. the soil of bear island and of liachoff islands is said to consist only of sand and ice with such quantities of mammoth bones as almost to compose its chief substance. the remains are not only found around the mouths of the great rivers, as would be the case if the carcasses had been washed down from more southern localities in the interior of the continent, but are imbedded in the frozen soil in such circumstances as to indicate that the animals had lived not far from the localities in which they are now found, and they are exposed either by the melting of the ice in unusually warm summers, or by the washing away of the sea cliffs or river banks by storms or floods. in this way the bodies of more or less nearly perfect animals, even standing in the erect position, with the soft parts and hairy covering entire, have been brought to light."[ ] but these remains of the mammoth, though the best known, are not the only ones attesting extraordinary conditions: though of course in warmer latitudes we do not find perfect "mummies" with the hide and flesh preserved untainted. let us go to a warmer climate, to sicily, and read a description of the remains of the hippopotamus found there. i quote from sir joseph prestwich: "the chief localities, which centre on the hills around palermo, arrest attention from the extraordinary quantity of bones of _hippopotami_ (in complete hecatombs) which have there been found. twenty tons of these bones were shipped from around the one cave of san ciro, near palermo, within the first six months of exploiting them, and they were so fresh that they were sent to marseilles to furnish animal charcoal for use in the sugar factories. how could this bone breccia have been accumulated?... the only suggestion that has been made is that the bones are those of successive generations of _hippopotami_ which went there to die. but this is not the habit of the animal, and besides, the bones are those of animals =of all ages down to the foetus=, nor do they show traces of weathering or exposure.... "my supposition is, therefore, that when the island was submerged, the animate in the plain of palermo naturally retreated, as the waters advanced, deeper into the amphitheatre of hills until they found themselves embayed, as in a seine, with promontories running out to sea on either side and a mural precipice in front. as the area became more and more circumscribed the animals must have thronged together in vast multitudes, crushing into the more accessible caves, and swarming over the ground at their entrance, until overtaken by the waters and destroyed."[ ] our author then adds this summary of his argument: "the extremely fresh condition of the bones, proved by the retention of so large a proportion of animal matter, and the fact that animals of all ages were involved in the catastrophe, shows that the event was geologically, comparatively recent, as other facts show it to have been sudden." that it must have been a good deal more "sudden" than even this author will admit, is evident from the nature of the hippopotamus. i never thought that it was particularly afraid of the water, or likely to be drowned by any such moderate catastrophe as prestwich invokes in this singular volume. the reader must, however, note that this affair, like the entombment of the mammoth, certainly =took place since man was upon the globe=, even according to the uniformitarians. would it not be economy of energy to correlate the two together? but if man dates from "miocene times," as some contend, he must have witnessed half a dozen awful affairs like these, for there is scarcely a country on the globe that has not been under the ocean since then. let us proceed. but whither shall we turn to avoid finding similar phenomena? the vast deposits of mammals in the rocky mountains may occur to the reader. as dana says, they "have been found to be literally tertiary burial grounds." i need not go into the details of these deposits, nor of those in other places containing the great mammals which must have been contemporary with "tertiary man," for i would only weary the reader with a monotony of abnormal conditions of deposit--unlike anything now being produced this wide world over. we shall be stating the case very mildly indeed, if we conclude that the vast majority of the fossils, by their profuse abundance and their astonishing preservation, tell a very plain story of "speedy burial after death," and =are of an essentially different character= from modern deposits. prof. nicholson, in speaking of the remains of the zeuglodon, says: "remains of these gigantic whales are very common in the 'jackson beds' of the southern united states. so common are they that, according to dana, 'the large vertebrae, some of them a foot and a half long and a foot in diameter, were formerly so abundant over the country in alabama that they were used for making walls, or were burned to rid the fields of them.'"[ ] shortly before his death in , dana prepared a revised edition of his "manual," and in it he gives us quite a rational explanation of this case, as follows: "vertebrae were so abundant, on the first discovery, in some places that many of these eocene whales must have been stranded together in a common catastrophe, on the northern borders of the mexican gulf--possibly by a series of earthquake waves of great violence; or by an elevation along the sea limit that made a confined basin of the border region, which the hot sun rendered destructive alike to zeuglodons and their game; or by an unusual retreat of the tide, which left them dry and floundering under a tropical sun." (p. .) that is, this veteran geologist in his old age would not attempt to account for such abnormal conditions without a catastrophe of some kind. but if we use similar explanations for similar conditions, where shall we stop through the whole range of the rocks from the cambrian to the pleistocene? dana became very fond of this idea of earthquake waves, and invoked them to account for "the universality and abruptness" with which the species disappear at the close of "palaeozoic time," using as the generating cause the uplifting of the appalachian mountains, with "flexures miles in height and space, and slips along newly opened fractures that kept up their interrupted progress through thousands of feet of displacement," from which he says "incalculable violence and great surgings of the ocean should have occurred and been often repeated.... under such circumstances the devastation of the sea border and the low-lying lands of the period, the destruction of their animals and plants, would have been a sure result. the survivors within a long distance of the coast line would have been few."[ ] but as this sudden break in the life-chain "was so general and extensive that no carboniferous species is known to occur among the fossils of succeeding beds, not only in america and europe, but also over the rest of the world" (p. ), he is obliged to make his catastrophe by earthquake waves positively =world wide=. hence he adds: "the same waves would have swept over european land and seas, and there found coadjutors for new strife in earthquake waves of european origin." at the close of the mesozoic he uses similar language, though in this case he has the whole range of the mountains on the west of both north and south america, the rockies and the andes, in length a "third of the circumference of the globe," "undergoing simultaneous orogenic movements, with like grand results." (p. .) "the deluging waves sent careering over the land" would, he thinks, "have been destructive over all the coasts of a hemisphere," and "may have made their marches inland for hundreds of miles" (p. ), sweeping all before them. i should think so; but then what becomes of this doctrine of uniformity? personally, i have not the slightest objection to these "deluging waves sent careering over the land," for i feel sure that just such things have occurred, and on just such a scale as our author pictures, for, as he says, the destruction of species "was great, =world-wide=, and one of the most marvelous events in geological history." (p. .) but it seems to me that here we have an enormous amount of energy going to waste. others have demanded a continent to explain the appearance of a beetle in a certain locality; but here we have a great world-wide catastrophe to explain the sudden disappearance of merely a few species. why not utilize this surplus energy in doing other necessary work, that has certainly been accomplished somehow, but has hitherto gone a-begging for a competent cause? the only thing i object to in dana's view of the case is his way of having these "exterminations" take place on the installment plan. for in that way we have to work up a great world catastrophe to do only a very limited amount of work, and then have to repeat the thing another time for a similarly limited work, =when one such cosmic convulsion is competent to do the whole thing=. i plead for the "law of parsimony," and the economizing of energy. the vast shoals of carcasses which seem to be piled up in almost every corner of the world are _prima facie_ evidence that our old globe has witnessed some sort of cosmic convulsion. the exact cause, nature, and extent of this event we may never have sufficient facts to determine, though two or three additional facts having a bearing on the subject will be considered in the following chapters. footnotes: [ ] "manual," p. . [ ] _pop. sci. mo._, vol. xxi, pp. , . [ ] "manual," p. . [ ] "geol. and min.," vol. i., pp. - . ed. . [ ] "theoretical geol.," p. . london, . [ ] "old red sandstone," pp. , - . [ ] _pop. sci. news_, may, , pp. - . [ ] "histor. geol.," p. . [ ] "acadian geol.," p. . [ ] "mammals," p. . [ ] "on certain phenomena, etc.," pp. - . [ ] "ancient life-history," p. . [ ] "manual," p. . chapter x change of climate another great general fact about the fossil world may be stated about as follows: =all of the fossils= (save a very few of the so-called "glacial age," and they admit of other easy explanation) =give us proofs of an almost eternal spring having prevailed in the arctic regions, and semi-tropical conditions in north temperate latitudes; in short give us proofs of a singular uniformity of climate over the globe which we can hardly conceive possible, let alone account for.= the proofs of this are almost unnecessary, as this subject of climate has been pretty well discussed of late years. and it was the overwhelming evidence on this point which forced lyell and so many others to decide against the theory of croll, which called for a regular rotation of climates, for they said that the fossil evidence was wholly against such a view. howorth has given an admirable argument on this point in chapter xi of his second work on the glacial theory[ ] and to it i would refer the reader for details which i have not the space to reproduce here. this author first remarks: "the best thermometer we can use to test the character of a climate is the flora and fauna which lived while it prevailed. this is not only the best, but is virtually the only thermometer available when we inquire into the climate of past geological ages. other evidence is always sophisticated by the fact that we may be attributing to climate what is due to other causes; boulders can be rolled by the sea as well as by sub-glacial streams, and conglomerates can be formed by other agencies than ice. but the biological evidence is unmistakable; cold-blooded reptiles cannot live in icy water; semi-tropical plants, or plants whose habitat is in the temperate zone, cannot ripen their seeds and sow themselves under arctic conditions.... we may examine the whole series of geological horizons, from the earliest palaeozoic beds down to the so-called glacial beds, and find, so far as i know, no adequate evidence of discontinuous and alternating climates, no evidence whatever of the existence of periods of intense cold intervening between warm periods, but just the contrary. not only so, but we shall find that the differentiation of the earth's climate into tropical and arctic zones is comparatively modern, and that in past ages not only were the climates more uniform, but more evenly distributed over the whole world." without attempting to follow through the whole series of formations we may note a few characteristic statements of the text-books. thus dana says of the cambrian: "there was no frigid zone, and there may have been no excessively torrid zone." while of the silurian coral limestones of the arctic regions he says: "the formation of thick strata of limestone shows that life like that of the lower latitudes not only existed there, but flourished in profusion."[ ] howorth thus quotes colonel fielden, the arctic explorer, regarding the fossil sclerodermic corals of the silurian, widely distributed in the arctic regions: "these undoubted reef-forming corals of the silurian epoch were just as much inhabitants of warm water in northern latitudes at that period as are the sclerodermata of to-day in the indo-pacific and atlantic oceans.... these corals were forms of life which must have been tropical in habits and requirement." in fact coral limestones of the carboniferous system are the nearest known fossiliferous rocks to the north pole, and from the strike of the beds must underlie the polar sea. in the words of howorth, "coal strata with similar fossils have occurred all round the polar basin ... and may be said, therefore, to have occupied a continuous cap around the north pole."[ ] again i quote from howorth regarding the mesozoic rocks: "this very widespread fauna and flora proves that the high temperature of the secondary era prevailed in all latitudes, and not only so, it pervaded them apparently continuously without a break. there is no evidence whatever, known to me, that can be derived from the fauna and flora of secondary times, which points to any period of cold as even possible. there are no shrunken and stunted forms, and no types such as we associate with cold conditions, and no changes evidenced by intercalated beds showing vicissitudes of life." the following is from nordenskiold, as quoted by howorth, and refers to the whole geological series: "from what has been already stated it appears that the animal and vegetable relics found in the polar regions, imbedded in strata deposited in widely separated geological eras, uniformly testify that a warm climate has in former times prevailed over the whole globe. from palaeontological science no support can be obtained for the assumption of a periodical alternation of warm and cold climates on the surface of the earth."[ ] and now we have the equally positive language of a. r. wallace: "it is quite impossible to ignore or evade the force of the testimony as to the continuous warm climate of the north temperate and polar zones =throughout tertiary times=. the evidence extends over a vast area both in space and time, it is derived from the work of the most competent living geologists, and it is absolutely consistent in its general tendency ... whether in miocene, upper or lower cretaceous, jurassic, triassic, carboniferous or silurian times, and in all the numerous localities extending over more than half the polar regions, we find =one uniform climatic aspect of the fossils=."[ ] of course in all this i am taking the various kinds of fossils in the traditional chronological order. but i shall presently show on the best of authority that man existed in "pliocene" or perhaps "miocene times," and in view of such an admission we have, even from the standpoint of current theory, a vital, personal interest in this question of climate. let us take, then, the following from james geikie, the great champion of the glacial theory, on the climate of the arctic regions at this part of the =human epoch=: "miocene deposits occur in greenland, iceland, spitzbergen, and at other places within the arctic circle. the beds contain a similar (similar to the "most luxuriant vegetation" of switzerland) assemblage of plant-remains; the palm-trees, however, being wanting. it is certainly wonderful that within so recent a period as the miocene, a climate existed within the arctic regions so mild and genial as to nourish there beeches, oaks, planes, poplars, walnuts, limes, magnolias, hazel, holly, blackthorn, logwood, hawthorn, ivy, vines, and many evergreens, besides numerous conifers, among which was the sequoia, allied to the gigantic _wellingtonia_ of california. this ancient vegetation has been traced up to within eleven degrees of the pole."[ ] according to dana and other american geologists the "glacial period" is only a variation intervening between the warm tertiary and the equally warm "champlain period," and it was during the latter that the mammoth, mastodon, etc., roamed over europe, asia, and america. of the climate then indicated, when all acknowledge that man was in existence, this author says: "the genial climate that followed the glacial appears to have been marvelously genial to the species, =and alike for all the continents, australia included=. the kinds that continued into modern time became dwindled in the change wherever found over the globe, notwithstanding the fact that genial climates are still to be found over large regions."[ ] in his "geological story briefly told," he uses even stronger language: "the brute mammals reached their maximum in numbers and size during the warm champlain period, and many species lived then which have since become extinct. those of europe and britain were largely warm-climate species, such as are now confined to warm temperate and tropical regions; and only in a warm period like the champlain could they have thrived and attained their gigantic size. the great abundance of their remains and their condition show that the climate and food were all the animals could have desired. they were masters of their wanderings, and had their choice of the best."[ ] "the genial climate of the champlain period was _abruptly_ (italics dana's) terminated. for carcasses of the siberian elephants were frozen so suddenly and so completely at the change, that the flesh has remained untainted." (id. p. .) i quite agree with this author that the evidence is conclusive as to the climate and food being "all the animals could have desired," and that they must have "had their choice of the best." but it seems to me that in following out their theory these authors have not left the poor creatures very much to choose from. for as the inevitable result of their theory in arranging the plants as well as the animals in chronological order according to the percentages of living and extinct forms, they have already disposed of, and consigned to the "early" tertiaries, etc., all the probable vegetation on which these animals lived, and thus have nothing left on which to feed the horse and bison, rhinoceros and elephant, etc., away within the arctic circle, except the few miserable shrubs and lichens which now survive there. but this strange, inconsistent notion of dana's that the so-called glacial phenomena lie in between the warm tertiary and the equally warm "champlain period," is easily understood as the survival of the notion, so tenaciously held even later than the middle decades of the nineteenth century, that man was =not= a witness of any of the great geological changes. when the evidence became overwhelming that man lived while the semi-tropical animals roamed over england, the "glacial period" still remained as a sort of buffer against the dangerous possibility of extending the =human= period back any further. i am not aware that this venerable scientist ever became quite reconciled to the idea of "tertiary man," though in his "manual" he mentions a few evidences in favor of this now almost universally accepted opinion. as for the real teachings of the drift phenomena there is no need of explanation here. at the very most they are confined to a quite limited part of the northern hemisphere, there being no trace of them in alaska, nor on the plains of siberia, where now almost eternal frosts prevail.[ ] in fact they are practically confined between the rocky mountains and the missouri river on the west, and the ural mountains on the east; and with a little common sense infused into the foundation principles of the science we will cease to be tormented with a "glacial nightmare." much of the drift phenomena with the raised beaches are certainly =later= events than most of the other geological work, but are inseparably connected with the general problem in their explanation. even from the ordinary standpoint, i am not aware that the elaborate argument of howorth has even been satisfactorily answered. indeed, i feel almost like saying that this writer's various contributions to the cause of inductive geology mark the beginning of the dawn. hence it may suffice here to merely call attention to the great simplicity introduced into this vast complexity of the glacialists, by the positive assurance of this author that the "drift period" and the pleistocene =end together=, and join onto the modern; or perhaps i ought rather to say that the so-called glacial phenomena lie in between the true fossil world and our modern one. "thus, in regard to the pleistocene mammals, the view is now generally accepted that, in every place where they have been found in a contemporary bed, that bed underlies the till, and is therefore pre-glacial. as in other places, so here (scotland), teeth and bones of mammals have occurred in the clay itself; but in all such cases they occur sporadically and as boulders. as mr. james geikie says, 'they almost invariably afford marks of having been subjected to the same action as the stones and boulders by which they are surrounded; that is to say, they are rubbed, ground, striated, and smoothed.'"[ ] and again: "=the pleistocene fauna, so far as i know, came to an end with the so-called glacial age.=" (id. p. .) from a recent notice in _nature_[ ] it would seem that even dr. h. woodward, of the british museum, supports this general view in his "table of british strata," by the statement that the glacial deposits contain =only derived fossils=. but this is such a decided simplification of the problem of climate that i am utterly at a loss to understand how any one can still cling to the complex and highly artificial arrangement of numerous "interglacial" periods, to account for a few bones of mammals or a few pockets of lignite; and how they can even place between the "glacial period" and our times the "genial champlain period," with it, as dana says, "=abruptly terminated=," and becoming "=suddenly= extreme as of a single winter's night." howorth, in the latter part of the chapter already quoted from (pp. - ), gives a good review of this subject of intermittent climates, and strongly supports his contention that the =stratigraphical evidence= all points to the fact that the pleistocene forms are always older than the drift-beds, and where the flora and fauna of the pleistocene occur in the drift, they do so only as boulders; that, in fact, as he says in his preface, "the pleistocene flood ... =forms a great dividing line= in the superficial deposits," separating the true fossil world from the modern. i have hardly the space to repeat here my argument about the extremely fanciful way in which geologists classify the various members of the tertiary group and the pleistocene. and yet i must say a few words. i have tried to show the utter nonsense of the common custom of classifying these beds according to the percentage of living and extinct forms which they contain, when the real fact is that the number and kinds of the ancient life-forms which have survived into the modern era is a purely fortuitous circumstance, being limited solely to those lucky ones which could stand the radical change from a tepid water or a genial air to the ice and frosts which they now experience, to mention only one circumstance of that cosmic convulsion which we now know to have really intervened between that ancient world and our own. =yet it is on such evidence only= that these pleistocene forms are separated from the tertiaries, or that the tertiaries themselves are classified off--at least as far as the invertebrates and the plants are concerned. no one claims that the so-called glacial beds can be sharply distinguished from other deposits on purely mechanical make-up. indeed, i am strongly of the opinion that very many archaean soils, totally unfossiliferous themselves, and resting on unfossiliferous rocks, have been assigned to the "glacial age," merely because their discoverers did not know what else to do with them. when beds contain fossils, the latter are the one and only guide in determining age; but in view of the purely arbitrary character of this method of classifying off the tertiary and post-tertiary rocks, i do not see where we are going to =draw the line= when we once admit that the post-tertiary beds contain only "derived fossils." it seems to me truly astonishing that shrewd reasoners, like howorth and dr. woodward, have not seen the dangerous character of this precedent which they have admitted. for with that marvelous climate of all geological time continuing right up to that fatal day when it was "abruptly terminated," and the mammoth and his fellows were caught in the merciless frosts which now hold them, the percentage of all the lucky forms of life, plants, invertebrates, or mammals, which could stand such a change and "persist" into our modern world, must be =utterly nonsensical as a test of age= even from their standpoint. in resuming the main argument of this chapter, i need only summarize by saying that the evidence is conclusive that all geological time down to this sharp "dividing line" was characterized by a surprisingly mild and uniform climate over all the earth. the modern period is characterized by terrific extremes of heat and cold; and now little or nothing can exist where previously plant and animal life flourished in profusion. this radical and world-wide change in climate, therefore, demands ample consideration when seeking a true induction as to the past of our globe. that it was no gradual or secular affair, but that the climate "became =suddenly= extreme as of a single winter's night," the siberian "mummies" are unanswerable arguments. =that it occurred within the human epoch= all are now agreed. footnotes: [ ] "the glacial nightmare and the flood," pp. - . [ ] "manual," pp. , - . [ ] op. cit., pp. - . [ ] id., p. . [ ] "island life," pp. , - ; "nightmare," pp. - . [ ] "historical geology," p. . [ ] "manual," p. . [ ] p. , edition of . [ ] see dana's "manual," pp. , ; also "the glacial nightmare," pp. - , , etc. [ ] "great ice age," p. ; "nightmare," p. . [ ] see _nature_ april , , p. . chapter xi degeneration there is another great general fact about the fossil world which seems to be a natural corollary from the one already given about climate. it is this: =the fossils, regarded as a whole, invariably supply us with types larger of their kind and better developed in every way than their nearest modern representatives, whether of plants or animals.= this fact also is so well known that it needs no proof. through the whole range of geological literature i do not know of a word of dissent from this general fact by any writer whatever. proof therefore is not necessary, though a brief review of a little of the evidence may refresh our memories. to begin with the cambrian, dana says: "the pteropods, among mollusks, were much larger than the modern species of the tribe. the trilobites even of the lower cambrian comprise species as large as living crustaceans. the ostrapods are generally larger than those of recent times."[ ] again, in speaking of the general character of the cambrian fossils, he says: "the types of the early cambrian are mostly identical with those now represented in existing seas, and although inferior in general as to grade [in the "phylogenic series"], they bear no marks of imperfect or stunted growth from unfit or foul surroundings." (p. .) the well known mollusk, _maclurea magna_, which is so enormously abundant in the silurian, is often eight inches in diameter, and the astounding cephalopod genus, _endoceras_, consisting of twenty species, found only in two divisions of the lower silurian, has left shells over a foot in diameter, and ten or twelve feet long! of the fishes of the devonian we have, among other remarks of a similar character, the following: "the dipnoans, or 'lung-fishes,' were represented by gigantic species called by newberry _dinichthys_ and _titanichthys_, from their size and formidable dental armature.... a still larger species is the _titanichthys clarki_ of newberry, in which the head was four feet or more broad, the lower jaw a yard long. this jaw was shaped posteriorly like an oar blade, and anteriorly was turned upward like a sled runner."[ ] one of the ancient eurypterids from the old red sandstone of europe has a length of six feet, which is more than three times that of any crustacean now living. while a gigantic isopod crustacean from the same strata had a leg the basal joint of which was three inches long, and three-quarters of an inch through, which is larger than the whole body of any modern species. the ancient "horse-tails," "ground-pines," ferns and cycads were trees from to feet high, and their carbonized stems and leaves make up many of our largest and best beds of coal. compared with them the modern representatives are mere herbs or shrubbery. of the gigantic insects of the devonian and carboniferous beds we might make similar remarks. some of the ancient locusts had an expanse of wing of over seven inches; while many of the ancient dragon-flies had bodies from a foot to sixteen inches long, with wings a foot long and over two feet in spread from tip to tip. here is james geikie's summary of the leading types of the palaeozoic: "many palaeozoic species were characterized by their large size as compared with species of the same groups that belong to later times. thus, some trilobites and other crustaceans were larger than any modern species of crustaceans. the palaeozoic amphibians also much exceeded in size any living members of their class. again, the modern club-mosses, which are insignificant plants, either trailing on the ground or never reaching more than two feet in height, were represented by great lepidodendroid trees." sternberg, in speaking of some of the frogs which he found in the permian of texas, says: "i found several skulls that measured over a foot from the end of the chin to the distal point of the horns.... i think when alive the frog must have been six feet long."[ ] he mentions another specimen which was "about feet long," the head of which was "about inches in length," with jaws "more powerful than those of an ox." of the monstrous dinosaurs of the mesozoic rocks one hardly needs to speak. "they were the most gigantic of terrestrial animals, in some cases reaching a length of or feet, while at the same time they had a height of body and massiveness of limb that, without evidence from the bones, would have been thought too great for muscle to move."[ ] they abound in both the old and the new world. of the gigantic mammals of the tertiary beds of the western states, it would also be superfluous to speak; their gigantic size is known by every high school pupil, or every one who has visited any important museum in europe or america. we may perhaps be reminded again that all the species of these "older" rocks are extinct species. i have already suggested the grave doubts on this point, regarding the great mass of the lower forms of life, plant and animal; but we will let that pass. but let us take some of the "late" tertiary and pleistocene mammals, which cannot be distinguished from living species, and how do we fare? it is the same old story; the moderns are degenerate dwarfs. the hippopotamus (_h. major_) is a good one to start with, for flower and lydekker[ ] say that it "cannot be specifically distinguished from _h. amphibius_" of africa. this gigantic brute used to live in the rivers of england and western europe. the text-books generally say in "pliocene times," because, i suppose, no one has the courage to suggest that it lived under the ice of the "glacial period." we are always pointed to the wool on the rhinoceros and the mammoth as indicating a somewhat cool climate, but the well known amphibious habits of the hippopotamus cannot be so easily disposed of. but if, as i believe, this world never saw a foot of ice at the sea level till the end of the "pleistocene period," to speak after the current manner, the problem becomes very simple. in that case the time of the hippopotamus in england was neither earlier nor later than that of the palms and acacias of the "early" tertiary or mesozoic rocks, or than that of the mammoth, lion, and hyena of the pleistocene. there is as we now know absolutely nothing but an out-of-date hypothesis to indicate that they did not all live there together. we may, if we choose, try to dovetail those conditions into the present on the basis of uniformity and slow secular change, by assuming a few million years for the process, but there is neither a particle of evidence nor of probability that the hippopotamus was not contemporary alike with the palms of the eocene and the elephants and lions of the post-tertiary. as for the mammoth itself, which flower and lydekker have intimated may turn out identical with _e. columbi_ and _e. armeniacus_, and thus the direct ancestor of the modern asiatic elephant (_e. indicus_), some have argued that its average size was not greater than that of the existing species of india and africa. but nicholson says that it was: "... considerably larger than the largest of living elephants, the skeleton being over sixteen feet in length, exclusive of the tusks, and over nine feet in height."[ ] dana is equally positive: "the species was over twice the weight of the largest modern elephant, and nearly a third taller."[ ] the upper incisors or tusks were very much longer than in the modern species, being from ten to twelve feet long, and sometimes curved up and back so as to form an almost complete circle. as these tusks continue to grow throughout life, their enormous length is, i take it, a proof of much greater longevity and thus of greater vitality than in the cases of the modern species. the latter is simply a degenerate. and so i might go on with the edentates, the ungulates, the rodents, the carnivores, etc., for the same thing must be said of all. as sir william dawson[ ] remarks: "nothing is more evident in the history of fossil animals and plants of past geological ages than that =persistence or degeneracy are the rule= rather than the exception.... we may almost say that all things left to themselves =tend to degenerate=, and only a new breathing of the almighty spirit can start them again on the path of advancement." in spite of the long popular views of cuvier, every modern scientist admits that the great lion and hyena of the pleistocene are identical with the living species of africa. many say the same thing of the fossil bear as compared with the modern brown bear and the grizzly, though, as dana remarks of all three, lion, hyena, and bear, "these modern kinds are dwarfs in comparison." i quote again from dana: "thus the brute races of the middle quaternary on all the continents exceeded the moderns greatly in magnitude. why, no one has explained."[ ] this was in . in the last edition of his "manual," published shortly after his death, he has this to say in addition: "a species thrives best in the region of fittest climate. =in the pleistocene, the fittest climate was universal.= geologists have attributed the extinction of most of the species and the dwindling of others to the cold of the reindeer epoch. it is the only explanation yet found, though seemingly insufficient for the americas." (p. .) however, since the discovery of the pictures of the reindeer and the mammoth drawn and even painted =side by side= on the caverns of southern france, undoubtedly from life and by the same artist, we do not hear so much about the "reindeer epoch," and the "mammoth epoch." a little thought should have suggested long ago that it was more reasonable to suppose the reindeer, glutton, musk-ox, etc., to have been originally adapted to the high mountains and table lands of that ancient world, than to imagine all the fauna careering up and down over continents and across seas like a lot of crazy scandinavian lemmings, as the migration theory involved. but most geologists seem never to have had any use for mountains or plateaus, except to breed glaciers and continental ice-sheets. but the only point which i wish to insist upon here is that the cause, =whatever it was=, that made such a zoological break at the "close" of the pleistocene, and which compelled the shivering, degenerate survivors, that could not stand the new extremes of frost and snow, to shift to the tropics--this cause was certainly competent to do a good deal more work in the way of "extinction" or "dwindling" of species than the uniformitarians have generally given it credit for. and in summing up this matter regarding the size and physical development of species, we must confess that we find in geology no indication of inherent progress upward. variation there is and variation there has been, even "mutations" and "saltations," but with one voice do the rocks testify that the general results of such variation have not been upward. rather must we confess as a great biological law, that =degeneration has marked the history of every living form=. footnotes: [ ] "manual," p. . [ ] pp. - . [ ] _pop. sc. news_, may, , p. . [ ] dana, "manual," p. . [ ] "mammals, etc.," p. . [ ] "ancient life-history," p. . [ ] "manual," p. . [ ] "modern ideas of evolution," appendix. [ ] "geol. story briefly told," p. . chapter xii fossil men there is still another fact which we must consider ere we can frame any wise or safe induction regarding the geological changes. it is this: =man himself, to say nothing of numerous living animals and plants, must have witnessed something of the nature of a cosmic convulsion--how much it is the object of our search to find out.= even according to the ordinary text-books, he must have seen the uplifting of the greater part of the mountain chains of the world; while he certainly lived in conditions of climate, and of land and water distribution, together with plant and animal surroundings, which preclude the possibility of dovetailing those conditions into the present order of things on any basis of uniformity. by this proposition i simply mean that man must have witnessed a cosmic geological catastrophe of some character and of some dimensions--the true nature and probable limits of this catastrophe ought to be the chief point of all geological inquiry. but instead of this method, instead of finding out whether our present world was ever a witness of such an event, the founders of the science began at the little end of an assumed succession of life (involving a preposterous supernatural knowledge of the past), and gradually worked up a habit of explaining everything in terms of uniformity long decades before they would acknowledge that man or the present order of things had anything to do with this fossil world. the evidence on this latter point finally became overwhelming; but with their habit of uniformity well mastered, and their long, single file of life succession all tabulated off and infallibly fixed, modern geologists have hitherto refused to look at the whole science from this new point of view, or to reconstruct geological theory if need be in accordance with a true modern induction. and in this proposition the reader will understand that i believe in what is called "tertiary man." i am aware that a few scientists still contest this view, but the evidence (from the standpoint of current theory) seems to me to be overwhelmingly against them. but in this fact, if it be a fact, that man lived under the wholly strange and different conditions of "pliocene" or perhaps "miocene times," is =the very strongest possible argument= that i can conceive of for the necessity of a complete reconstruction of geological theory--i mean, of course, apart altogether from the preposterous way in which the life succession was assumed and built up and then treated as an actual fact. it was when this grim fact of man's inseparable connection with the fossil world was borne in upon me, that i began to realize the possibility and imperative necessity of reconstructing the science on a truly inductive basis. i shall not undertake to give a complete up-to-date argument for "miocene" or even "pliocene man." the subject is still under discussion as to =just how far back= along this thin line of receding life forms man actually did live, and from the peculiar methods now in vogue which are so wholly subjective in character, it would seem to be capable of settlement in almost any way one chooses. however, whole volumes are being written on the subject, and the end is not yet. but there is no denying that human remains have frequently been found in strata which, but for their presence, would have been assigned a place far back in "tertiary time." the existence of strong evidence for "tertiary man" no one would think of denying. in all this, of course, i am considering the question from the common uniformitarian standpoint. but why should it be necessary for us to positively settle the question as to just how far back in geological time man actually did live? for those who have attentively read my statement of the unscientific methods of classifying these tertiary and post-tertiary beds--or all the others for that matter--i need not here add any further argument if the accepted succession of life is, to put it as mildly as possible, not quite a scientific certainty; if the time-honored custom of classifying these so-called "superficial" beds by their relative percentages of extinct and living forms rests under a shadow of suspicion as to its scientific accuracy; if, above all, we do not at the beginning prejudice the whole case by the assumption of uniformity, =what need is there of determining whether "pliocene" or "miocene" shells are found with these fossil human remains?= that man lived in western europe contemporary with those giants of the prime, the elephant and the musk-ox, the rhinoceros and the reindeer, the lion, the cape hyena, and the hippopotamus, at which time a very different distribution of land and water prevailed over these parts, with a radically different mantle of climate spread over all, no one will deny for a moment. such facts are now found in the primary text-books for our children in the public schools. but since geologists still classify the rocks as they do, and give a time value to percentages of extinct and living species of marine shells, etc., we are in a measure compelled to take the matter where we find it, and enquire how far back in geological time, i.e., among what kinds of fossils, are human remains found? one of the best popular works on the subject that i know of is "the meeting-place of geology and history," ( ) by sir j. w. dawson; though, like all other works of its kind written from the religious standpoint, it endeavors as far as possible to minimize the evidence in support of man's geological antiquity. this author thinks that dr. mourlan, of belgium, has "established the strongest case yet on record for the existence of tertiary man." (p. .) it is that of some worked flints and broken bones of animals "imbedded in sands derived from eocene and pliocene beds, and supposed to have been remanie by wind action." prestwich[ ] has brought forward similar facts; and though the evidence in favor of the genuine geological character of these remains seems to me little if any better than that from the auriferous gravels of california, i am willing to =take them as reported=. dawson speaks of the nearly entire human skeleton described by quatrefages from the lower pliocene beds of castelnedolo, near brescia, and only answers it with a sarcastic remark about the well developed skull of this ancient man. "unfortunately the skull of the only perfect skeleton is said to have been of fair proportions and superior to those of the ruder types of post-glacial men. this has cast a shade of suspicion on the discovery, especially on the part of evolutionists, who think it is not in accordance with theory that man should retrograde between the pliocene and the early modern period instead of advancing."[ ] lastly, we have the following about the miocene: "there are, however, in france two localities (puy, courney and thenay), one in the upper and the other in the middle miocene, which have afforded what are supposed to be worked flints." he adds that "the geological age of the deposits seems in both cases beyond question;" but contents himself with a derisive answer about these chipped flints being possibly "the handiwork of miocene apes." this language, coming from such a source, would seem as good evidence as is needed to prove that man was contemporary with, and that his remains are now found among the fossils of the middle miocene. for it must be remembered that these are reluctant admissions drawn from this illustrious scientist, who was one of the last champions of the old ideas about the "recent" origin of man. as pres. asa mahan of cornell has said, "admissions in favor of truth from the ranks of its enemies constitute the highest kind of evidence." at any rate, i shall treat this point as already proved, =for whether this particular instance is accepted or not, practically all modern writers admit the fact of "middle tertiary man."= i have already alluded to the recently discovered paintings on the cave walls of southern france, where reindeer, aurochs, horses and mammoths have been reproduced with striking accuracy and skill, and of such an age that they have in places been covered by stalactites over two inches in thickness. the marquis de nadaillac,[ ] who has given the best description of these interesting antiquities that i have been able to see, remarks that "the drawing is wonderful," and that "we are justly astonished to find such artistic performances in times so distant from ours, and in which we did not suppose a like civilization." i have not seen the geological date to which these remains have been assigned, but doubtless it is the very "latest" part of the pleistocene--they show far too high a development for "miocene" or even "pliocene times." but i should like to be shown some good and sufficient reason for saying that these men are not just as likely to have been contemporary with the middle tertiary fauna and flora as any others. =some men were as commonly admitted.= and in the name of sacred common sense, if the human period is thus elastic enough to stretch out over the pleistocene, the pliocene, and clear back to the "middle miocene," =why can't we do the same for all of man's strange companions=, the mammoth and the cape hyena, the reindeer and the hippopotamus, the lion and the musk-ox, etc.? the usual sneers about it being impossible for this apparently incongruous mixture to live side by side in the same district must now cease. they certainly did live side by side, as is shown by these companion pictures of the mammoth and the reindeer in the very southern part of sunny france, to say nothing of the numerous cases where the bones of the above mentioned animals are all mixed together indiscriminately. how is it unreasonable to suppose that these elephants, lions and hippopotami lived beneath the "early" tertiary palms, cinnamons, and mimosas of the lower elevations, while the reindeer, musk-ox and glutton lived beneath the maples, birches and beeches of the high mountain sides? some such conditions must have existed, for that magnificent world, whose ruins we now find buried beneath our feet, was a =homogeneous and harmonious= unit in its plant and animal life, in spite of the fables upon which we have so long been fed in the name of geological science. things which are equal to the same thing must be equal to one another; hence the plants and animals which were contemporary with the same creature (man) must have been =contemporary with each other=; and hence there is absolutely nothing to forbid the idea that man and his pleistocene companions were really contemporary with the flora and fauna of the middle tertiary. hence we may now proceed to inquire what geological changes have occurred since the "middle of the miocene," according to the accepted teachings of geology. our first point must be that of climate, and i have already given abundant evidence to show that at that "time" an abundant warm-climate vegetation mantled all the arctic regions. as already quoted from wallace, throughout the whole arctic regions, and during the whole of geological time, "we find one uniform climatic aspect of the fossils," and "it is quite impossible to ignore or evade the force of the testimony as to the continuous warm climate of the north temperate and polar zones throughout tertiary times." that this astonishingly mild and uniform climate prevailed over these regions until and during the time of the mammoth, we ought not to have a shadow of doubt. =what single bit of positive evidence is there to show that it did not?= that he must have had some such vegetation on which to feed is certain, and there is no proof of any previous interruption of these conditions save a series of hypotheses. he and his fellows browsed on semi-tropical and warm temperate plants far within the arctic circle, if there happened to be land there, doubtless over the very pole itself; but suddenly!! lo, something caught him with the grip of death-- "and wrapped his corpse in winding-sheet of ice, and sung the requiem of his shivering ghost." who has not read of their untainted meat now making food for dogs and wolves? their stomachs are well filled with undigested food, showing, as one author remarks, that they "were quietly feeding when the crisis came." dr. hertz recently reported one not only with its stomach full of food, but with its mouth full, too. no wonder that even an orthodox geologist like prof. dana is compelled to say that these things prove "that the cold finally became =suddenly= extreme, as of a single winter's night, and knew no relenting afterward." here then is one very notable geological event which has taken place within the human epoch, and the only thing of its kind of which geology has an undeniable record, viz., a sudden and radical change in the earth's climate; =a cosmic affair, and not a local phenomenon=. i need not here attempt to discuss the how of this world catastrophe as it must have been, or the other changes inseparably involved. the fact itself is as certain as man's own existence. the next division of our subject, in further consideration of the changes that have taken place since man's existence, as stated at the beginning of this chapter, relates to the changes of land and water distribution since "middle miocene times." and here again i shall try to take the classification of these rocks just as i find them. the first thing which impresses us is the extremely fragmentary distribution of the miocene and pliocene beds. not, however, that they are uncommon nor yet of small extent. on the contrary they are scattered over america and eurasia--and all the rest of the globe for that matter--like the spots on a leopard, or the warts on a toad's back, till it becomes one of the unsearchable mysteries of the science how these innumerable patches can be got down under the ocean to receive their load of sediment, without deluging the surrounding regions in a similar manner. but then, to be sure, fresh-water lakes will answer the same purpose, and are particularly indicated when the proportion of plants and terrestrial animals is =in excess= of the true marine fossils. and so enormous fresh-water basins are described here and there, with the great mammals crowding about their margins in their zeal to become fossilized, that the mountain tops may be saved from going under once more--or perhaps i should say to enable the modern writers to get some of these strata puckered up to their full height before these "late" tertiary deposits were made. this mountain making business is another affair that geologists would like to have take place on the installment plan, but unfortunately it seems to have been nearly all postponed till the very close of "geological time." this arrangement of fresh-water lakes saves the central rocky mountain region from going down again beneath the deep. but it cannot save the alps, juras and appennines in europe, nor parts of the himalayas, and i know not what other mountains in asia, nor the coast region of california and oregon in america, to say nothing of large parts of the andes in south america, with regions in africa and australia. but what is the use of trying to figure out the amount of our earth which has been under the ocean since "middle tertiary times," and thus since man was upon it? to save the northern half of europe with all of canada from again going under at the close of the "tertiary period," geologists have spread out their continental ice sheets, and have asked them to do duty instead of water. but this is hardly sufficient, for the "upper" or "later" part of the so-called "glacial" deposits are clearly stratified; and so they either invoke a "=flood vast beyond conception=," as dana does in america for the "final event in the history of the glacier," or, as others prefer, the whole region is baptized again. as dawson says in his "meeting-place of geology and history," "=no geological event is better established than the post-pliocene submergence.=" but i must not weary the reader by dwelling on this monotonous repetition of catastrophes--for must they not have been catastrophic if such ups and downs of whole continents are crowded within the human period? we may allow a number of thousands of years for man's possible existence, but archaeology and history alike protest against the =millions= of years required to explain these continental oscillations on any basis of uniformity. one such period of horror ought to be enough for us, and to understand or explain it in a truly scientific manner, we must with it correlate the sudden and world-wide change of climate already described. one more point demands consideration ere we complete this subject of what man has witnessed of geological change. for, according to current theory =almost all the mountains have been either wholly formed or at least completed within quite "recent" times=: indeed many of the greatest mountain chains have been puckered up from the position of horizontal strata wholly since "miocene times," which for us means since man was upon the globe. thus dana in speaking of the part of western america which has been elevated since "miocene times," says that it-- "... probably included the whole of the pacific mountain border, from the line of the mississippi valley to the pacific coast line and outside of this line for one or more scores of miles."[ ] and he adds the significant words: "contemporaneously, similar movements were in progress over the other continents: along the andes, affecting half, at least, of south america; the pyrenees, carpathian alps, and a large part of europe; the himalayas and much of asia." (p. .) let us now take a brief glance at a few of the details of what these mountains were thus doing while man was living in semi-tropical england, or at least western europe. in speaking of foreign examples of tertiary mountain-making this author devotes especial attention to the alps and the juras, for their structure is better understood, having been more carefully studied. and of an example described by heim, already spoken of, he says: "one of the overthrust folds in the region has put the beds upside down over an area of square miles. fifty thousand feet of formations of the jurassic, cretaceous, eocene tertiary and miocene tertiary, were upturned =at the close of the miocene period=."[ ] with what a whack must this mighty mass of rocks have fallen on itself--miles in thickness, and turned "upside down over an area of square miles"!!! of course i am here taking the record just as i find it, as i have already discussed this matter of "overthrust folds." i need not give further examples from the other great mountain ranges. their structure is not so well understood as that of the alps, though doubtless when examined they will be found just as "young," and just as full of astonishing mountain movements as those already examined. but this much is already certain, that =practically over all the world the mountains were either completed or wholly raised from the sea level= during "late tertiary" and "early quaternary time." no wonder dana says that this fact "is one of the most marvelous in geological history." "it has been thought incredible that the orographic climax should have come =so near the end= of geological time, instead of in an early age when the crust had a plastic layer beneath, and was free to move; yet =the fact is beyond question=." ("manual," p. .) i think i have now abundantly proved the various heads of the proposition with which i began this chapter, viz., that even from the standpoint of the current theories:--[ ] ( ) man must have seen the entire elevation or at least the completion of practically all the great mountains of the world, such as the rockies, andes, alps, himalayas, etc. ( ) the relative distribution of land and water surface has--since man's advent as commonly stated--changed completely. the land and water have practically changed places over the greater part of the globe. ( ) man lived while the arctic regions had a mild soft climate, and he lived to see these conditions so suddenly changed that some of his dumb brute companions were caught in the waters and frozen so speedily that their flesh has remained untainted. other considerations show this change of climate to have affected the whole globe. the lesson to be drawn from this as the last fact in the line of cumulative evidence here presented, will be considered in the following chapter. footnotes: [ ] "controverted questions of geology," article iii., . [ ] "meeting-place," pp. , . [ ] _pop. sc. news_, feb. . [ ] "manual," p. . [ ] p. . [ ] (note. in this discussion i have purposely ignored the various instances where human remains have been reported from deposits of even greater "antiquity" than the middle tertiaries.) chapter xiii inductive methods in the first part of this book i tried to examine into the facts and methods which are commonly supposed to prove that there has been a succession of life on the globe. we found that this life succession theory has not a single fact to support it; that it is not the result of scientific research, but wholly the product of an inventive imagination; that no one kind of fossil has even been proved or can be proved to be intrinsically older than another, or than man himself; and hence that a complete reconstruction of geological theory is imperatively demanded by our modern knowledge. in the second part i have brought out the following additional facts: . the abnormal character of much of the fossiliferous deposits. . a radical and world-wide change of climate. . the marked degeneration in passing from the fossil world to the modern one. . the fact that the human race, to say nothing of a vast number of living species of plants and animals, has participated in some of the greatest of the geological changes--we really know not how to limit the number or character of these changes. surely a true spirit of scientific investigation would now begin to inquire, =how did these changes take place?= discarding the use of stronger language, it is at least utterly unscientific to begin somewhere at the vanishing point of a past eternity and formulate our pretty theories as to how this deposit was made, and how that was laid down, and the exact order in which they all occurred; while these "recent" deposits, in which our race and the plants and animals living about us are acknowledged to be concerned, are left over till the last, and we then find that they admit of absolutely no explanation. we ourselves, to say nothing of thousands of living species of plants and animals, have participated in some of the very greatest of the geological changes--we know not how many or how great. =these things must be first explained.= has anything happened to our world that will explain them? are there known forces and changes now in operation which, granting time enough, will amply and sufficiently explain these facts, as simply one in kind with those of the present day? to this last question we must admit that our historic experience, prolonged over several thousand years, utters a thundering =no!= volcanoes are every now and then breaking forth; but volcanoes and mountain ranges have nothing in common with one another as to structure and origin. no one claims that a single mountain flexure is now being formed or has been formed within the historic period. there are indeed "creeps" in the rocks in certain places, but these are not such as to contribute to the height of the mountains in which they occur, but rather the reverse. sudden changes of level within small areas have occurred, but neither in extent nor in kind do they furnish any key as to past changes of level; while the so-called "secular" changes are so microscopic in extent and so doubtful in character that they are utterly unworthy of consideration in view of the stupendous problems which we are trying to explain. the well-known work of eduard suess is a standing protest that such geological chances are =not now in progress=; for, in speaking of how the land and ocean have exchanged places in the past, zittel represents him as teaching that their "cause of origin until now =has not yet been discovered=."[ ] or, to quote the expressive words of suess himself, with which he concludes his discussion of this very subject: "as rama looks across the ocean of the universe, and sees its surface blend in the distant horizon with the dipping sky, and as he considers if indeed a path might be built far out into the almost immeasurable space, so we gaze over the ocean of the ages, but =no sign of a shore shows itself to our view=." (id. p. .) as for climate, i never heard any one suggest that cosmic changes of climate are now known to be going on, much less that =sudden= changes of the kind indicated by the north siberian "mummies" are in the habit of occurring. in fact, we must all own that the mountains, the relative position of land and water, as well as the climate of our globe, are each and all now in a state of stable equilibrium, and have been in this state since the dawn of history or of scientific observation. accordingly i ask, =how much time is needed= to account for the facts before us on the basis of uniformity? in common honesty will a short eternity itself satisfy the stern problem before us? i cannot see that it holds out the slightest promise of solving it; while, on the other hand, i am sure that, in dealing with the past of man's existence (theories of evolution and all other theories of origins whatever cast aside), we are not at liberty to make unreasonable demands of time. the evidence of history and archaeology is all against it. from the latter sciences it can be shown that at their very dawn we have, over all the continents, a group of civilizations seldom equalled since save in very modern times, and all so undeniably related to one another and of such a character that they prove a previous state of civilization in some locality =together=, before these scattered fragments of our race were dispersed abroad. we can track these various peoples all back to some region in southwestern asia, though the exact locality for this source of inherited civilization has never yet been found, and it is now almost certain that it is somehow lost in the geological changes which have intervened. for when we cross the well marked boundary line between history and geology, we have still to deal with men who apparently =were not savages=, men who with tremendous disadvantages could carve and draw and paint as no savages have ever done, and who had evidently domesticated the horse and other animals. but as to time, history gives no countenance to long time, i.e., what geologists would call long. good authentic history extends back a few score centuries, archaeology may promise us a few more. as for =millions= of years, of even a few =hundred thousands=, the thing seems too absurd for discussion, unless we forsake inductive methods, and assume some form of evolution _a priori_. hence it ought to be evident that no amount of learned trifling with time will solve our problem without supposing some strange event to have happened our world and our race, long ago, and before the dawn of history. i see no possible way for scientific reasoning to avoid this conclusion. ignoring for the present the chaldean deluge tablets, and what rawlinson calls the "consentient belief" in a world-catastrophe "among members of all the great races into which ethnologists have divided mankind," which like their civilization has the earmarks of being =an inheritance= from some common source before their dispersion, we may note that most geologists now admit the certainty of some sort of catastrophe since man was upon the earth. i might mention quatrefages and dupont, boyd dawkins, howorth, prestwich, wright and sir william dawson, with many others. even eduard suess teaches a somewhat similar local catastrophe, though like the others only as a reluctant concession to the insistent demands of chaldean history and archaeological tradition. but all of these affairs are mere makeshifts in view of the tremendous demands of the purely geological evidence, and all alike (save perhaps those of wright and howorth) labor under the strange inconsistency of supposing that such an event could occur without leaving abundant and indelible marks upon the rocks of our globe. while in view of the evidence given through the previous pages, i insist that the purely geological evidence of a world catastrophe is immeasurably stronger than that of archaeology, that in fact the whole geological phenomena constitute a cumulative argument of this nature. but if this be granted, we must then inquire, what was its nature? and what its extent? the former is quite easily answered: the latter problem is still somewhat beyond our reach. as to its character, the evidence is very plain. it was a veritable cataclysm of some sort: it deals with great changes of land and water surface. if the geological succession is but a hoary myth, and if we find countless modern living species of plants and animals mixed up in all the "older" rocks, we cannot ignore these in a rational and unprejudiced reconstruction of the science. but, ignoring these, we must remember that =even the tertiary and post-tertiary deposits are absolutely world wide, and are packed with fossils of living species=. not a continent and scarcely a country on the globe but contains great stretches of these deposits, laid down by the sea where now the land is high and dry. the sea and land have practically shifted places over all the globe since man and thousands of other living species left their fossils in the rocks. it is only the stupendous magnitude of these changes which has made our scientists reluctant to admit the possibility of such a catastrophe. with the myth of a life succession dissipated, a broad view of the fossil world cannot fail to convince the mind of the reality of some such cosmic convulsion, and convince it with all the force of a mathematical demonstration. great groups of animals have dropped out of sight over all the continents, and their carcasses have been buried by sea water where we now find high plateaus or mountain ranges. ignoring completely the abundant fossils in the so-called "older" rocks, and fixing our attention entirely on the tertiary and pleistocene beds that are acknowledged to be closely connected with the human race and the modern world, we still have =a problem in race extinction alone= that appalls the mind. the mammoth, rhinoceros and mastodon, together with "not less than thirty distinct species of the horse tribe," as marsh says, =all disappear from north america at one time=, and the most ingenious disciple of hutton and lyell has been puzzled to invent a plausible explanation. but when we consider that at this same "geological period" =similar events were occurring on all the other continents=--the huge ground-sloths (megatheriums) and glyptodons in south america; "wombats as large as tapirs," and "kangaroos the size of elephants" in australia; the mammoth and woolly rhinoceros in eurasia; together with an enormous hippopotamus, as far as england is concerned, to say nothing of those great bears, lions and hyenas, with a semi-tropical vegetation, =all disappearing together at the same time=, or shifting to the other side of the world--it becomes almost like a deliberate insult to our intellectual honesty to be approached with offers of "explanations" based on any so-called "natural" action of the forces of nature. but when, in addition to all this, we consider the fact that those human giants of the caves of western europe were contemporary with the animals mentioned above, =and disappeared along with them at this same time=, while mountain masses in all parts of the world crowded with marine forms of the so-called "older" types positively =cannot be separated in time from the others=, it becomes as certain as any other ordinary scientific fact, like sunrise or sunset, that our once magnificently stocked world =met with some sudden and awful catastrophe in the long ago=; and is it in any way transgressing the bounds of true inductive science to correlate this event with the deluge of the hebrew scriptures and the traditions of every race on earth? we have already seen how dana supposes =two= such events, one at the close of the "palaeozoic age," and the other at the close of the "mesozoic," merely to account for the astonishing disappearance of species at these periods when the fossils are arranged in taxonomic order; but if we once admit such an event =with man and all the other species contemporary with one another=, where shall we limit its power to disturb the land and water and churn them all up together, leaving the present simply as the ruins of that previous world? the fact is, the current geology is wholly built up from the cambrian to the pleistocene on the =dogmatic denial= that any such catastrophe has occurred to the world in which man lived, for =one= such event happening in our modern homogeneous world is enough to make the whole pretty scheme found in our text-books tumble like a house of cards. like the patient and exact observations of the ptolemaic astronomers, which accumulated volumes of evidence contradicting their own theories, and which in the hands of copernicus and galileo, kepler and newton, sealed the doom of astronomical speculation and laid the foundations of an exact science of the heavens; so have the indefatigable labors of thousands of geologists accumulated evidence which strikes at the very foundation of the current uniformitarianism, and casts a pall of doubt over every conclusion as to how or when any given deposit of the "older" rocks was produced. here we must leave the question for the present. the possibility of such a world-wide catastrophe, which might account for the major part of the geological changes, needs no apology here. the slightest disturbance of the nice equilibrium of our elements would suffice to send the waters of the ocean careering over the land; and in the abundance of astronomical causes competent for such disturbance we cease to regard such an event as necessarily contrary to "natural law." the possibility of such a thing no competent scientist now denies; it is the problem of =recovery= from such a disaster which makes the perplexity. but incredible or not as the latter may be regarded, i claim to have established a perfect chain of scientific argument proving a world-wide catastrophe of some sort since man was upon it. but this fact, if once admitted, strikes at the very foundation of the current science, and bids us readjust our theories from this view-point. the venerable scheme of a life succession =becomes only the taxonomic or classification series of the world that existed before this disaster=, and it becomes the business of our science to find out how many and what deposits were =due to this event=, and what were accumulated during the =unknown period= of previous existence. those of us who wish to speculate can then let our imaginations have free play as to the uncounted ages before that event; but the "phylogenic series" as a rational scientific theory is in limbo forever. inductive geology, therefore, deals not with the formation of a world, but =with the ruins of one=; it can teach us absolutely nothing about origins. the latter problem lies across the boundary line in the domain of philosophy and theology, and to these systems of thought we may cheerfully leave the task of readjustment in view of the facts here presented. a few disconnected thoughts along these lines i have ventured to insert here, not strictly as a part of my purely scientific argument, but as an appendix. footnote: [ ] "history," p. . appendix appendix reflections in the preceding pages i have endeavored to develop a scientific argument pure and simple. yet i do not feel called upon to apologize in any way for attempting now to show the connection between an inductive scheme of geology as set forth in the body of this work and the religion of christianity; though my remarks along this line must necessarily be very brief. the most fundamental idea of religion is the fatherhood of god as our creator. the only true basis of morality lies in our relationship to him as his creatures. during the latter half of the nineteenth century the biblical idea of a creation at some definite and not very remote period in the past became much modified by reason of certain theories of evolution, which explained the origin of plants and animals as the result of slow-acting causes, now in operation around us, prolonged over immense ages of time. these theories, though built up wholly on the current geology as a foundation, were yet supposed to be firmly established in science, and after a spirited discussion among biologists for a few years, were almost universally accepted in some form or other by the religious leaders of christendom. and though the "theistic evolution" of recent years may be supposed to have modified somewhat the stern heartlessness of pure darwinism, it still leaves the christian world quite at variance with the old pauline doctrines regarding good and evil, creation, redemption, the atonement, etc. and these are not the only effects of the general acceptance of these ideas as an explanation of the origin of things. we see their moral effects in the generation now coming on the stage of action--men educated in an atmosphere of evolution, and accustomed from youth to the idea that all progress, whether in the individual or the race, is to be reached only by a ceaseless struggle for existence and survival at the expense of others. in the words of sir william dawson, these doctrines have "stimulated to an intense degree that popular unrest so natural to an age discontented with its lot ... and which threatens to overthrow the whole fabric of society as at present constituted."[ ] this popular and perfectly natural application of the evolution doctrine to every-day life is certainly intensifying, as never before, the innate selfishness of human nature, and, in every pursuit of life, embittering the sad struggle for place and power. perhaps no other one cause and result serve more plainly to differentiate the present strenuous age from those that have gone before. the hitherto undreamed-of advantages and creature comforts of the present day, instead of tending toward universal peace and happiness, are apparently only giving a wider range to the discontent and depravity of the natural human heart. so much so, that any one familiar with the history of nations cannot but feel a terrible foreboding creep over him as he faces the prospect presented to-day by civilised society the world over. the only remedy for the many and increasing evils of our world is the old-fashioned religion of christ and his apostles. and this applied, not to the state, but to the individual. the soul-regenerating truths of christianity have always, wherever given a proper test by the individual, resulted in moral uplift and blessing. ecclesiastical policies and ideas have always, wherever allowed to influence civil legislation, resulted in oppression and tyranny. what has geology to do with all this? it has much to do with it. correct ideas of geology will remove a great many vain notions--i had almost said superstitions--regarding our origin, which now pass under the name of science. and in thus removing false ideas it =leaves the ground cleared= for more correct ideas regarding =creation=, and thus for truer concepts of =morality=, the old idea of "must" and "ought" based on our relation to god as his creatures. mark the words i have used. =inductive geology can never prove creation.= it may remove obstructions which have hitherto obscured this idea, but this is the utmost limit of any true science. inductive geology removes forever the succession-of-life idea, and thus may =suggest= the only seeming alternative, viz., creation as the definite act of the infinite god. before this awful yet sublime fact, with all the fogs of evolution and metaphysical subtleties cleared away, the human mind stands to-day as never before within historic times. with a fairly complete knowledge of the chemical make-up of protoplasm, with a good acquaintance with the life history and reproduction of living cells, we yet =know nothing of the origin of life=. with a good working knowledge of variation, hybridization, etc., =we know nothing of the origin of species=. while with a fairly good understanding of the present geographical distribution of species, and of where their fossils occur in the rocks, we are =profoundly ignorant of any particular order= in which these species originated on our globe, or whether they all took origin at =approximately one and the same time=. in short, having reached out along every known line of investigation, until we have apparently reached the limits of the human powers in investigation and research, twentieth century science must stand with uncovered head and bowed form in presence of that most august thought of the human mind, "=in the beginning god created=." and yet, personally, i am firmly convinced that the origin of life and of our cosmos, was according to law, and the laws of nature. as has been said, how could the origin of nature be contrary to nature? how could the origin of present forms and conditions be in any way at variance with the laws by which these forms or conditions are maintained? and while i do not consider it a very promising field of research, we ought to have no more reluctance, _per se_, to considering the manner in which the first cell or the first species was formed, than the way in which a chicken is produced from the egg. of course in either case we must have the materials, and some outside cause to originate the conditions and conduct the process; they both require the immanent presence and fostering care of the great creator. in this connection i beg leave to quote somewhat at length from my book, "outlines of modern science and modern christianity." "we are getting no nearer the real mystery in the case by saying that all the tissues of the chick are built up by the protoplasm in the egg. the protoplasm in the toes is the same as that in the little creature's brain. why does the one build up claws and the other brain cells? does memory guide these little things in their wonderful division of labor? but they all started from one original germ cell, hence they all ought to have the same memory pictures. or have they entered into a mutual-benefit arrangement, like the members of a community, as haeckel would have us believe, each contributing by actual desire and effort, i suppose, an individual share to the general progress of the whole?--no; they have all the appearance of being mere automata working at the direct bidding of a master mind. every step of the process needs a creator, just as much as the first cell division. in the words of one of the highest of scientific authorities, 'we still do not know why a certain cell becomes a gland-cell, another a ganglion-cell; why one cell gives rise to a smooth muscle-fibre, while a neighbor forms voluntary muscle;' and this also 'at certain, usually predestined, times in particular places.'[ ] and in the same way the idea of a creator would not be disposed of, even if we could possibly hit upon the probable process of world-formation. we would not, by understanding the process, really get at the cause of the phenomena, any more than we do now at the real cause of life. from the scientific method the real mystery remains as much behind the veil as ever before." (pp. , .) again i quote from this same work: "the origin of organic nature could not well have been otherwise than by natural process. do we understand all natural processes? at some time life was not in existence on our globe. all agree that it had a beginning. even if created by the great creator, the living was at some time formed from the not-living or the not-material. it does not take even huxley's famous 'act of philosophic faith' to believe that. so that, in spite of all the haze that has been thrown about this question, the biblical creation of the organic from the inorganic is no more contrary to, or even outside of, natural law than is evolution.... "but see what we avoid. according to the bible, death in even the lower animals (and consequently all misery and suffering: the less is included in the greater) is only the result of sin on the part of man, the head of animated nature, a reflex or sympathetic result, if you will. but with evolution we have countless millions of years of creature suffering, cruelty, and death before man appeared at all, cruelty and death that ... have no moral meaning at all, save as the work of a fiend creator, or a bungling or incompetent one."[ ] the author then gives a quotation from leconte, illustrating the extremely various ways in which matter and energy act on the different planes of their existence, while "the passage from one plane upward to another is not a gradual passage by sliding scale, but at one bound. when the necessary conditions are present, a new and higher form of force at once appears, like birth into a higher sphere.... it is no gradual process, but sudden, like birth into a higher sphere."[ ] the argument then proceeds as follows: "the living at some time originated from the not-living. =we call it creation.= can any one find a better name? it is preposterous to call it a process of development or evolution due to the inherent properties of the atoms, and effected by them alone. and yet it is doubtless as much according to 'natural law' as are the invariable and exact combinations of chemistry. we do not understand the ultimate reasons for chemical affinity any more than we do for gravitation. they are only expressions of the methodical, order-loving mind of deity. creation was only another action of the same mind, and we are not really finding any new difficulty when we say that the processes or the reasons for creative action are beyond our comprehension. when we can really solve some of the myriad problems right before our eyes, it will be time enough to complain about creation being incomprehensible or contrary to 'natural law.' "well, then, remembering that, even according to huxley's 'act of philosophic faith,' the origin of the living from the not-living must at some time have taken place according to natural law, =why should we suppose that such a process was confined to one example=? if, when the young planet 'was passing through physical and chemical conditions which it can no more see again than a man can recall his infancy,' the 'necessary conditions' were favorable for one such creation of life, =why not a few billion=? would the production of a few billion such beginnings of protoplasm be any less 'natural' than of one alone? remember, however, that both the arrangement of these 'necessary conditions,' as well as the endowing of matter with these 'properties,' not only requires a cause, but this cause must be intelligent, for there is indisputable design in this first origin of life.... the food for a developing embryo might, for aught that we know, be conveyed to it direct from the ultimate laboratories of nature, and it thus be built up by protoplasm in the usual way, without the medium of a parent form--other than the great father of all. or would it be any less according to natural law to believe that a bird passed through all the usual stages of embryonic development from the not-living up to the full-fledged songster of the skies =in one day=--the fifth day of creation? and =if one example, why not a million=? for, remember that the youthful earth was then passing through strange conditions, 'which,' as huxley says, 'it can no more see again than a man can recall his infancy.'"[ ] omitting some remarks about embryology, i continue this quotation as follows: "but what 'law' would be violated in this springtime of the world if, instead of twenty years or so for full development, the first man passed through all these stages =in one day=--the sixth of creation week? he might as well have originated from the not-living as the evolutionist's first speck of protoplasm, for he certainly now starts from a mass of this same protoplasm, identical, as we have seen, in all plants and animals. "and by originating thus, he would escape that horrible heritage of bestial and savage propensities which he would get through evolution, a heritage that would make it not his fault, but his misfortune, that sin and evil are in the world, and which would also shift the responsibility for the evidently abnormal condition of 'this present evil world' off from the creature to the creator, and change to us his character from that of a loving father, fettered by no conditions in his creation, to that of either a bungling, incompetent workman or a heartless fiend; for, though i am almost ashamed to write the words, the god of the evolutionist must be either the one or the other." (p. .) * * * * * =with an appreciation nurtured by centuries of study of god's larger book, baffled often though she has been, and disappointed many times in the words she has endeavored to spell out, science to-day proclaims its subject, its title page, which she has now at last deciphered, "in the beginning god created the heaven and the earth." footnotes: [ ] "modern ideas of evolution," p. . [ ] "_nature_," may , , pp. , . [ ] "outlines," etc., p. . [ ] "evolution and religious thought," pp. - . [ ] "outlines," etc., p. , . report on "illogical geology" having read the foregoing argument, will you now do the publishers and the author the favor of _filling out the following blank_ and mailing this slip, or a copy of it, to us as early as possible? it makes no difference to us even if your opinion is _adverse_. the modern heretic co. s. hill st., los angeles, cal. cut out here +-------------------------------------------------------------------- | . what is your opinion of part i as an exposure of the evolution | theory? | | | | . how can it be improved? | | | | . what fact or facts have been omitted from part ii that should be | included in a true, safe, induction regarding the past of our | globe? | | | | . other remarks. | | | | | | name......................................... | | street and number............................ | | city..................... | |profession or occupation........................... modern science and modern christianity by george mccready price the evolution theory in its whole range, from the nebulous cloud, the cooling earth, and the origin of life, through geology and biology up to the moral nature of man, carefully discussed in a popular style. no one, after reading it, could for a moment suppose that the evolution theory had been proved by sound scientific arguments, while the moral and religious tendencies of the doctrine are shown to be anti-christian to the last degree. cloth bound, pages, _net_, cents. postage extra. god's two books by george mccready price a pamphlet covering that part of the evolution theory which deals with geology, archæology, darwinism, and ethics. it is especially full on geology and darwinism, and presents many facts and arguments on these subjects not found in anything now published. (in preparation). paper covers, about pages, cents, postpaid. the modern heretic co. so. hill st., los angeles, cal. the modern heretic a magazine of primal orthodoxy george mccready price, editor we believe that the claims of evolution, "higher criticism," new theology, new thought, spiritism, etc., are unscientific and un-christian. we realize that we are in a small minority, and that to assail these doctrines is to-day called _heresy_. but we have chosen our position deliberately, and shall abide by the consequences. this journal will try to give the most recent discoveries in geology, biology, physiology and archæology, and to discuss their bearings on the christian religion; and we think that no intelligent person can afford to be without its regular visits. monthly; c per year; sample copies free. the modern heretic co. s. hill st. los angeles, cal. * * * * * transcriber's note: punctuation has been standardised, in particular, missing periods have been supplied where obviously required. all other original errors and inconsistencies have been retained, except as follows; (the first line is the original text, the second the passage as currently stands): must less of the co-existing faunas of other much less of the co-existing faunas of other which it discusses from a purely scientfic which it discusses from a purely scientific works of dana, le conte, prestwich, and geikie works of dana, leconte, prestwich, and geikie of looking into the =geneology of an idea=. of looking into the =genealogy of an idea=. history of science did a stranger halucination history of science did a stranger hallucination we know they are today in "recent" deposits we know they are to-day in "recent" deposits the author then gives a quotation from le conte, the author then gives a quotation from leconte, but is is equally evident that each successive but it is equally evident that each successive dominated mediaeval scolasticism and made it dominated mediaeval scholasticism and made it the glacian nightmare and the flood, the glacial nightmare and the flood, larger species is the _titnichthys clarki larger species is the _titanichthys clarki happening in our modern homogenous world is enough happening in our modern homogeneous world is enough widespread numulitic limestones of the eocene widespread nummulitic limestones of the eocene of organic creation on the instal ment plan, of organic creation on the instalment plan, numulites or mammals positively were not living nummulites or mammals positively were not living here and there to make this incredible thicknss, here and there to make this incredible thickness, about it came to the recognized, other about it came to be recognized, other the bison is today absolutely extinct, the bison is to-day absolutely extinct, see le conte, "evol. and religious thought," see leconte, "evol. and religious thought," they are directed rather to the empyrical method they are directed rather to the empirical method fitting "like a glove" on the preceeding. fitting "like a glove" on the preceding. le conte, "evol. and rel. thought," pp. , leconte, "evol. and rel. thought," pp. , and spcial monographs in german and french. and special monographs in german and french. but to incrase this antiquity by saying but to increase this antiquity by saying lions and monkys, hippopotami and crocodiles, lions and monkeys, hippopotami and crocodiles, and rhinoceroces, now live beneath the palms, and rhinoceroses, now live beneath the palms, scientists who can elaborate geneological trees of descent scientists who can elaborate genealogical trees of descent have taken for these excedingly numerous have taken for these exceedingly numerous the pleistocene mammals and the middle tertiary flora the pleistocene mammals and the middle tertiary flora literature is fairly innundated with new names; literature is fairly inundated with new names; a noted paiaeontologist for finding a pupa a noted palaeontologist for finding a pupa the theories of the igenous origin of the crystalline rocks the theories of the igneous origin of the crystalline rocks went to school toegther, served in the same wars, went to school together, served in the same wars, =or are now to be found iiving in our modern world= =or are now to be found living in our modern world= e.g. gratolites and numulites e.g. gratolites and nummulites these davonian and other rocks are absolutely these devonian and other rocks are absolutely it cannot save the alps, juras and appenines it cannot save the alps, juras and appennines without leaving abundant and indellible marks without leaving abundant and indelible marks which it can no more see again than a can can recall which it can no more see again than a man can recall and yet refuse the =evidently complemntary= dposits and yet refuse the =evidently complementary= deposits pages of the ordinary text-boks. pages of the ordinary text-books. these is no telling what hosts of similar facts there is no telling what hosts of similar facts but so far as the text-boks tell us are but so far as the text-books tell us are as recent as the numulitic limestones of the eocene as recent as the nummulitic limestones of the eocene [footnote : "old red sandstone," pp. - - .] [footnote : "old red sandstone," pp. , - ] for thousands of skletons are found in localities for thousands of skeletons are found in localities is easily understod as the survival of the notion, is easily understood as the survival of the notion, the dim past, and all these semitropical plants had the dim past, and all these semi-tropical plants had =better established than the post-piiocene submergence.=" =better established than the post-pliocene submergence.=" example described by helm, already spoken of, example described by heim, already spoken of, the former is qulet easily answered: the former is quite easily answered: =race extinction alone= that appals the mind. =race extinction alone= that appalls the mind. which in the hands of copernicus and galilio, which in the hands of copernicus and galileo, chapter xii inductive methods chapter xiii inductive methods in the last edition of his "=manual=," in the last edition of his "manual," pre-conceived theory would at the suggestion of such preconceived theory would at the suggestion of such evolution and metaphysical subtilties cleared away, evolution and metaphysical subtleties cleared away, transcriber's note: every effort has been made to replicate this text as faithfully as possible. italic text has been marked with _underscores_. superscript letters are preceded by ^. oe ligatures have been expanded. the geologists' association. on the red chalk of england. by the rev. thos. wiltshire, m.a. f.g.s. president of the geologists' association. a paper read at the general meeting, th april, . london: printed for the association, and published at the office of "the geologist," , strand. . list of plates. plate i. fig. . inoceramus coquandianus, from speeton. . fragment of inoceramus, striated by glacial action, muswell hill. . nautilus simplex, hunstanton. . inoceramus crispii, hunstanton. . i. tenuis, hunstanton. plate ii. . spongia paradoxica, hunstanton. . siphonia pyriformis, hunstanton. . cardiaster suborbicularis, hunstanton. . ostrea frons, muswell hill. . o. vesicularis, hunstanton. . exogyra haliotoidea, hunstanton. . cytherella ovata, speeton. . cristellaria rotulata, speeton. . trochocyathus (?) ----, hunstanton. plate iii. , _a._ vermicularia elongata. upper and under surface of two different specimens, speeton. . vermicularia umbonata, hunstanton. . serpula irregularis, hunstanton. . s. antiquata, hunstanton. . bourgueticrinus rugosus, hunstanton. . diadema tumidum, hunstanton. . cidaris gaultina (?), hunstanton. plate iv. . terebratula biplicata, _a._ mag. surface, hunstanton. . t. semiglobosa, _a._ mag. surface, speeton. . kingena lima, _a._ mag. surface, hunstanton. . terebratula capillata, _a._ mag. surface, hunstanton. . belemnites attenuatus, hunstanton. . b. listeri, speeton. . b. ultimus, speeton. . b. minimus, speeton. on the red chalk of england a paper read th april, by rev. thomas wiltshire, m.a., f.g.s., etc., president. persons in general take as the type or representative of chalk the material which mechanics employ for tracing out rough lines and figures. it is a substance of a bright white colour, somewhat yielding to the touch, and capable of being very easily abraded or rubbed down. but the geologist gives a much wider interpretation to the term, not limiting it by these few characteristics; and, accordingly, he includes under the same title many strata which would hardly be so grouped together by the uninitiated. for instance, there is at the base of the upper portion of the cretaceous system a certain hard, often pebbly, and highly coloured band, which, notwithstanding its great departure from the popular type, is nevertheless styled in geological language the "red chalk." this stratum, the subject of the present paper, nowhere forms a mass of any great thickness or extent; perhaps if thirty feet be taken as its maximum of thickness, four feet as its minimum, and one hundred miles as its utmost extent in length, the truth will be arrived at. it may be said, also, to be peculiar to england, for the _scaglia_, or red chalk of the italians, has little in common with that of our country. the two differ widely in appearance, in situation, and in fossils. the first view of the seam in the north is to be obtained about six miles north-west of flamborough head, in yorkshire, near the village of speeton, where its structure, dip, and general appearance can be remarkably well studied. speeton is a small village, a place of no great note in the business-world, yet of much fame amongst the lovers of geology, inasmuch as in its neighbourhood there are several interesting formations, to one of which--the speeton clay--it gives a name. in these days of rapid travelling, the village has the great convenience of a railway-station, from whence the cliffs below can be reached without the slightest difficulty. [illustration: lign. .--map of part of yorkshire, lincolnshire, and norfolk, showing the outcrop and range of the red chalk.] as i wish to conduct the members of the association to the red chalk _in sitû_, let us suppose that, starting from some locality near the hull and scarborough railway, we have taken tickets for speeton station, and have in due time arrived at that latter place. on alighting from the train we must direct our steps to the houses in front, and then inquire the way to the sea-shore, above which we shall be standing at some considerable height--say four hundred feet. we shall be told to walk by the church, to turn to the right along a little lane, and then to look for an obscure path which passes across the fields. we shall soon afterwards, being on high ground, be able, by the light of nature, to find a way down to the sands below. whilst descending, let us survey the scene that lies before us. it is a grand one, rendered picturesque by the broken ground, the solitude, and the sounding of the waves. right ahead, there is the open bay of filey; on the left hand, the town of filey and its brig; not a ship, as one might imagine, but a huge mass of rocks of the coralline oolite, jutting out to sea at right angles from the shore, like a pier formed by human hands, and crowned on the land-side by strangely cut pinnacles of pink and rugged drift. on the right hand there are the high and perpendicular white chalk cliffs of the flamborough range. as we pass down we shall meet with a gulley or bed of a small stream, in all probability quite dry, by following the winding course of which we shall reach the shore. this gulley passes over an escarpment of diluvial matter (the whole place being in confusion through the effects of small landslips), and traverses the red chalk itself, the first trace of which will be rendered visible by means of rolled fragments, which the force of the stream has at different times detached. it will be only here and there that we shall find the red chalk _in sitû_, because sometimes vegetation, sometimes diluvium, sometimes fallen masses, entirely conceal its real position. however, there will be plenty of rounded pieces at the feet. some of these had better be examined on the spot, in order that we may gain a clear perception of the appearance of the bed, should we meet with it again. these pieces are found to be hard and rough to the touch, and of a bright red tinge, though occasionally marked with streaks of white. most likely on some of their sides a fossil or two will be seen peeping out; a blow from a hammer will divulge still more. so plentiful are the rolled fragments, that a few hours' work will satisfy the conscience, and fill the pockets of the traveller. if i might be permitted to give advice to any member of our association who should hereafter visit the place, it would be this--that it would be well for him to carry away moderate sized boulders entire, rather than to break them on the spot. the fossils will best be developed at leisure. the material is so hard, and the fossils so brittle (especially the belemnites and serpulæ), that imperfect specimens only will result from the quick and rough treatment of the hammer. the "find" will not produce any very great variety, only numbers; terebratulæ, serpulæ, and belemnites will be all that will be obtained. having now procured specimens, we had better walk southward along the shore; after a short time will be seen a fine perpendicular section of this particular stratum; we shall notice it is bounded on the one side by the white chalk, to which it is parallel; on the other by the speeton clay, which is not conformable to it, that is, not parallel. the thickness of the bed of the red chalk is at this place, as i said just now, about thirty feet. first of all, taking it in descending order, that is to say, having reached its limit at the white chalk, and retracing our steps in the direction of filey, we notice about twelve feet of red matter containing serpulæ, and we note that the upper portion of this division is much filled with greyish nodules, showing that the change from the white chalk to the red is gradual. next comes a bed of about seven feet thick, of darkish white chalk; and finally, another bed of about twelve feet thick, of bright red chalk, containing belemnites and terebratulæ. the whole is followed by the speeton clay, of which a short and accurate account will be found in no. of the geologist magazine. the line of division between these two being well marked by runs of water, which are caused by the percolation through the chalk being stopped by the impervious clay. the speeton clay is singular in some of its characteristics. at its upper portion, in contact with the red chalk, it contains fossils belonging to the neocomian or greensand era, whilst at the lower part there are the representatives of the kimmeridge clay. and thus it would appear to be one of those peculiar formations which have resulted from a number of beds thinning out, and becoming absorbed into each other. three of the well-marked fossils of the speeton clay may be adduced: _belemnites jaculum_; a small crustacean, _astacus ornatus_; and a large hamite, called _hamites beanii_. to the south of the red chalk at speeton, and adjoining it, occurs, as i lately mentioned, the white chalk. the fossils in this part are not numerous; an inoceramus, a terebratula, and rarely an ammonite, are found. but the white chalk higher up, that is, farther south, below flamborough head, near bridlington quay, is very fossiliferous, containing corals, echini, a bed of marsupites, as well as that very remarkable and extensive collection of marine forms, the silicified sponges, thousands of which can be seen at low water scattered up and down, and imbedded in the scars, or rocks. this chalk, however, has its drawbacks, for being very hard--indeed, so much so as to ring under the strokes of a hammer--specimens cannot be obtained without much trouble. i must make an exception with regard to the sponges. they are composed of silex; hence, long soaking in very dilute hydrochloric acid will do more and better work after the fossils have been brought home, than fifty chisels. the calcareous matter is slowly dissolved away, and then forms come into view as delicate and lovely as any that can be noted in the modern sponge tribe. most of the common kinds of the flamborough sponges will be found figured and named in professor phillips' geology of yorkshire; the rarer in the magazine of natural history for . let us now return to the village of speeton, and endeavour to follow the winding course of the red chalk to its visible termination, some hundred miles to the south-east, in the county of norfolk. by a reference to the map (page ), where the bed is laid down, it is seen that the red chalk adjoins the white chalk during its entire length; that it first takes a westerly direction for about twenty miles, and then suddenly turning at a sharp angle proceeds south-east for the remainder of its course. some persons might suppose when they see the map, that if they were to travel to any of the towns or villages near the line, they would of necessity be able to see the red chalk _in sitû_. no such thing; the upper soil, or vegetation, or man's work, may quite conceal all traces. it is only at natural sections like the cliffs just spoken of, or by other means, such as wells, &c., that we can acquire a true idea of the ground beneath us. who, for example, that lives in the city of london, could imagine, unless he had seen the fact for himself, when sewers were opened, or foundations cut, that he was dwelling over beds of gravel as bright and yellow as any that cover the paths of a flower-garden? when, therefore, the nature of the surface of the ground is such that the eyes cannot detect traces of any particular formation we may be in search of, we must seek other testimony, we must ask what have other men seen, and what have they recorded, and in whose custody have they placed the keeping of those facts. in the present case i can refer to two excellent works, to help us,--professor phillips' geology of yorkshire, and young and bird's survey of the yorkshire coast. let us turn to the latter. the authors write that in the year a mr. george rivis, of sherburn, bored for coal in a deep dale about a mile and a half south of staxton; the boring was continued for some considerable depth. first they passed through the white chalk, next came upon the red seam, and finally, at the depth of feet from the mouth of the bore, reached the speeton clay. thus then near staxton, a few miles west of speeton, the red chalk exists; there it is, though it may not be visible. if we proceed still farther west along the northern foot of the yorkshire wolds, it is possible that at knapton we shall actually see the red and white chalk again _in sitû_; for young and bird tell us that, at a clay-pit near that village, it was to be seen in their day. at north grimston, they add, the coloured chalk seems to be wanting, for at a copious spring issuing on the hill-side, about a mile above the village, the white chalk is seen lying immediately over the blue clay. this statement is not to be wondered at. look at the map (page ). not far from north grimston there must evidently be great unconformity of strata. notice several of the formations, instead of running parallel to one another, actually are at right angles. for instance, we have the speeton clay, the oolites, and the lias, almost perpendicular in direction to the white chalk, a little to the west of great driffield. such a condition of affairs must have resulted from great disturbances, and there would be nothing strange in a part of the series being displaced or altogether wanting. some miles to the south, near the town of pocklington, the strata are again parallel in direction to each other, and accordingly the red chalk is found, as before, at the base of the wolds. professor phillips, in his work on the geology of yorkshire, figures some red chalk fossils from goodmanham, near market weighton, and alludes to their also occurring at brantingham, not far from the river humber, the boundary of the county. thus, then, the red chalk has been traced through yorkshire; speaking roughly one might say, that it for the most part takes an undulating course at the base of the wolds; that it rises with a very gentle inclination from the sea near the village of speeton; that it proceeds nearly due west until it approaches the neighbourhood of malton, that it then suddenly changes its direction, and advances south-east until it sinks below the marsh-land six or seven miles to the west of hull, having occupied a distance of about fifty miles. we now cross the river humber, and find the red chalk again near the banks at a place called ferraby, to the west of barton in lincolnshire. the museum of the geological society of london possesses specimens taken from that part, and in a note attached to them there is this remark, that first came white chalk, then red chalk, then a blue clay; thus it is evident there is the same state of things prevailing as we had at speeton; and the same observation will apply to the appearance of the specimens themselves. but as we travel along the western base of the lincolnshire wolds, or chalk downs (for londoners would so term them), although we find the red chalk underneath the white, yet the blue clay beneath the red chalk is wanting; its place is supplied by a thick series of brown coloured sands, with included beds of sandy limestone, full of fossils like the kentish rag, only not possessing echini and belemnites. these beds have been referred to the lower greensand. only a few remarks can be offered in reference to lincolnshire. my intention was to have visited the base of the chalk-hills, and have gathered together new facts; i have not been able to do so; neither have i been successful in discovering any authors who have written much about that county. there is a great geological darkness over that land, and much remains to be done in working out its fossiliferous deposits. i can, however, speak confidently regarding louth. one might fancy, as the town is placed to the right of the dark line on the map, which marks the position of the red chalk, that louth could have nothing to do with the latter. but a friend who made some inquiries for me on the spot has forwarded two specimens, and says he saw them taken out of a chalk-pit at that town. they ran in veins, he writes, the lighter coloured over the darker, and were dug at no great distance below the surface. the bright red piece was just above where the springs arise--facts which correspond with evidence in other places. as the inclination of the plane of the strata is small, and rising towards the south-west (the direction of the strata being north-west), it is easily comprehended that the red chalk may exist under louth, and yet not appear at the surface of the ground until at some distance to the west of the town. at brickhill, near harrington, the seam also has been met with; a specimen of it can be seen in the museum of the geological society of london. this last and those from louth differ little in appearance or character from what may be obtained at the speeton beds. i have no more to say about lincolnshire, except that, according to the authority of geological maps, the red chalk of that county sinks and disappears below the marsh-lands, a few miles before reaching the sea. and now it is time to cross the wash, that great sea-bay, and land at hunstanton, a little village on the north-western coast of norfolk. as i am addressing a company of working geologists, i ought perhaps to say how in practice the locality can be arrived at, for it is not quite so easy to reach a place in reality as it is to see it on a map. to go to hunstanton, in the most ready way, a person must first reach lynn; whence an omnibus, starting in the afternoon, at three or four o'clock, from the lynn station, will convey passengers to the village. at hunstanton there are two hotels, and several lodging-houses. i should recommend the le strange arms, as being an old-fashioned comfortable inn, and nearer than the other to the section we are in quest of. perhaps it may be thought, why dwell so much upon hunstanton--its hotel--and its omnibus? i do so because at that village there is a most excellent natural section of the red chalk, better almost than at speeton, and different certainly in many respects. we will suppose that we have arrived at hunstanton, and are walking towards the shore in front of the le strange arms. a very few minutes will convey us to the wonderful cliff. i say wonderful, not from its height or length; for at its greatest height, under the lighthouse, it is not more than sixty feet; and it extends little more than a mile in length; but wonderful from its curious colour and general effect. [illustration: lign. .--hunstanton cliff (looking to the north)] the woodcut, copied from a water-colour drawing, made last autumn by a friend, will afford an idea of its appearance; but in it the absence of colour, of course, takes away from the beauty of the scene. the cliff itself may be divided into five portions: first, white chalk, forty feet thick; secondly, bright red chalk, four feet; thirdly, a yellow sandy mass, ten feet; fourthly, a dark brown pebbly stratum, forty feet; and, lastly, twenty feet of a bed almost black. these divisions do not run one into the other, as is the case in most geological strata, but keep quite distinct. thus the red chalk is as clearly separated from the white, as though the one had been covered by a broad band of paint. the same observation will hold good with respect to the others. it will readily be understood that when the sun shines upon the cliff, and lights up the bright white, the bright red, the pale yellow, and the dark brown and black, and casts a shadow over the mass of gaily tinted materials at the base, a picture is produced not easy to be surpassed in beauty, and certainly not to be fully appreciated unless it be actually seen. the bed of white chalk above the red is, at hunstanton, very fossiliferous; though rendered somewhat useless, like that of yorkshire, to the geologist, from its extreme hardness. amongst other shells, may be mentioned several kinds of serpulæ, belemnites, and ammonites. these last are occasionally very large: when i was at hunstanton, in the autumn, i found an example two feet in diameter; with great difficulty i extricated it from its matrix, breaking it in half during the operation; and, finally, had the mortification of discovering that its weight was so great i could not carry it away. the red chalk beneath, which is nearly four feet in thickness, is very full of fossils: belemnites, serpulæ, terebratulæ, corals, and many others, not to mention bones. the number of specimens on the table will testify to its richness in organic remains. sometimes it is soft and crumbling; but, generally speaking, it is very hard, gritty, of a bright red shade, and full of small dark-coloured siliceous pebbles; in this respect differing considerably from the red chalk of speeton--in which i have not seen pebbles. professor tennant, who has examined the hunstanton pebbles, informs me that they consist of _chalcedony_, _quartz_, _flint_, _slate_, and _brown spar_ or _carbonate of iron_. it also contains a great quantity of fragments of inocerami, and a curious ramifying sponge-like structure (there is one on the table), which also occurs in the white chalk above. something very similar to the ramifying sponge is seen on the surface of blocks on the sea-shore at the back of the isle of wight in the greensand formation, and one very like it on the calcareous grit of the yorkshire shore. you will observe these last to the north of filey, but nothing of the same appearance exists in the white chalk at speeton. underneath the red chalk of hunstanton occurs a yellow and brown pebbly sandstone, which was formerly supposed to contain no organic remains. mr. c. b. rose of yarmouth, however, has obtained many. this bed is termed in those parts "carstone," and much employed as a building-material. the cottages in that neighbourhood and on the road from lynn seem at a distance as though they had been constructed of masses of gingerbread, so great is the similarity in colour and appearance. the length of the red chalk, from end to end, at the hunstanton cliff is about , yards, and its greatest elevation at the point where it attains the top and quits the cliff is thirty-seven feet; hence its rise is very gradual, since its first appearance is nearly on a level with the beach. there are two other things worth observing at hunstanton. one is the lighthouse, which is upon the dioptric principle, the light being transmitted out to sea by means of glass prisms instead of the ordinary metal reflectors; and the other is a vestige of a raised sea-beach on the cliffs composed of rounded fragments of white and red chalk immediately reposing on the greensand. it is situated at the southward of the point where the red chalk crops out. we will now, if you please, quit hunstanton, and proceed towards lynn, keeping in the neighbourhood of the coach-road. if we could dig up the ground when we were within eight or nine miles of lynn, we should still see our old companion at our feet, for the red chalk has been recognised at the villages of ingoldsthorpe and dersingham. we shall soon meet it no more. at leziate, a little to the north-east of lynn, it becomes extinct. mr. c. b. rose, who always thought the red chalk would prove to be the equivalent of the gault, and who argued from the evidence of fossils and from the direction of the outcrops that the true gault and the red chalk must ultimately meet,--mr. rose, i say, has informed me that he has observed the red chalk and the gault incorporated together at leziate. henceforward to the south the red chalk is no more seen. thus, then, we have come to the termination of our journey. we have noted the beginning and the ending of the red chalk, we have also taken some account of its neighbours. we have noticed, too, that in yorkshire it for the most part reposes on the speeton clay, though in certain localities it is next the lias and kimmeridge clay, and that in lincolnshire and norfolk it rests on a dark brown pebbly mass supposed to belong to the lower greensand formation of the south of england. the red chalk has also been discovered in a very unexpected place, although not _in sitû_. i allude to the drift of muswell hill. in that collection of different materials, comprising examples from every formation from the london clay to the mountain limestone in a stratum of eighteen feet, the red chalk has been seen in a bouldered condition. by the kindness of mr. wetherell of highgate, i am enabled to exhibit specimens from the drift of muswell hill. any person who compares them with others from hunstanton, would declare they came from the same bed, so alike are they in appearance. there was a time no doubt when this red chalk had a more extended range: its presence in the drift of muswell hill, as well as in the drift of other places, implies as much. perhaps it may still exist elsewhere, deep down in the earth. in a well sunk at stowmarket a red substance was found under the white chalk, at a depth of feet; and in another well sunk at kentish town, the workmen met, at a depth of , feet below the surface, beneath the gault, a bed of red matter feet thick--some of this red matter appeared to contain belemnites. geologists are divided in opinion with respect to this deep-sunk red bed, which certainly is not always continuous (for instance, it was not found at a boring at harwich), and some incline to the opinion that it belongs to the new red, others that it is the equivalent of what is styled the red chalk. but it is difficult to give a solution at present. it is certain that in the gault formation, or near it, beds of a red colour are occasionally found. near dorking the lower greensand is capped by a local bed of bright red clay, eight feet thick. and examples of red clays from the gault of ringmer in sussex and charing in kent can be seen in the museum of the geological society of london. whether they have any relation with the red chalk proper of england depends upon the position which is given to that formation. geologists generally consider the red chalk as really equal to the gault. many of the fossils certainly are gault species; others no doubt belong to the lower chalk; and, therefore, probably it is better to regard it as an intermediate formation between the lower chalk and the lower greensand, which comes into being when the gault and upper greensand have almost thinned out. one of the members of our committee, mr. rickard, has been good enough to make me an analysis of the red chalk of speeton and hunstanton. the speeton is as follows:-- carbonate of lime, with a little alumina . peroxide of iron . silica . ----- . ----- from hunstanton-- carbonate of lime, with a little alumina . peroxide of iron . silica . ----- . ----- the latter of which agrees remarkably well with the colour of the specimen, for the red chalk of hunstanton is brighter than that of speeton. two specimens of the borings of kentish town, one a red argillaceous and the other a siliceous mass, gave the following results:-- argillaceous-- peroxide of iron . carbonate of lime . silica and alumina (chiefly the latter) . ----- . ----- siliceous-- peroxide of iron . carbonate of lime . silica, with a little alumina . ----- . ----- whether any connexion can be traced between these last two and the two former, i leave for others to decide. the following list of books may perhaps be useful to those who wish to further investigate the subject:--in professor phillips' geology of yorkshire, young and bird's survey of the yorkshire coast, dr. fitton's memoir of the strata below the chalk, taylor's hunstanton cliff (phil. mag. vol. lxi.), woodward's geology of norfolk, rose on the geology of west norfolk (phil. mag. for the years and ), will be found some account of the english red chalk. and in sedgwick and murchison on the structure of the eastern alps (geol. soc. trans. vol. iii. second series), sir. r. i. murchison on the geological structure of the alps (quart. geol. journal, vol. v.), prof. t. a. catullo on the epiolitic rocks of the venetian alps (quart. geol. journal, vol. vii), count a. de zigno on the stratified formations of the venetian alps (quart. journal geol. soc. vol. vi.), will be seen an outline of the scaglia or red chalk of italy. by the kindness of dr. bowerbank, messrs. wetherell, bean, leckenby, and rose, in permitting me to see the specimens in their respective cabinets, and to whom, as well as to mr. rupert jones, i must express great obligations for much valuable information, the accompanying list of the red chalk fossils of speeton, hunstanton, and muswell hill has been compiled. to the council of the geological society, i am also indebted for permission to figure from the society's museum the inoceramus crispii, on pl. i. fig. . list of fossils from the red chalk. key to table columns: s: speeton h: hunstanton mh: muswell hill s h mh cristellaria rotulata, d'orb. pl. ii. fig. × sowerby's min. conchology, tab. , page . (in the collection of mr. jones.) siphonia pyriformis. pl. ii. fig. × goldfuss petrifacta, tab. , fig. , page . (in the collection of mr. rose.) this is probably the head of the next. spongia paradoxica. pl. ii. fig. × geol. trans. , tab. , fig. , page . (in the collections of mr. rose and author.) bourgueticrinus rugosus. pl. iii. fig. × d'orbigny's hist. des crinoides, tab. , fig. - . (in the collections of mr. rose and author.) pentacrinites fittonii × × austin's crinoids, page . (in the collections of mr. rose, author, and mr. wetherell.) cardiaster suborbicularis, forbes. pl. ii. fig. × gold. tab. , fig. , page . (in the collections of mr. rose and author.) mr. rose's specimen is far better than the one figured. cidaris gaultina (?), forbes, dec. v. pl. iii. fig. × (in the collection of mr. rose.) spines with ridges, ridges, and ridges × × (in the collections of mr. rose and mr. wetherell.) diadema tumidum, forbes, dec. v. pl. iii. fig. × (in the collection of mr. rose.) serpula antiquata. pl. iii. fig. × sow. min. con. tab. , fig. , page . (in the collection of mr. rose.) serpula irregularis. pl. iii. fig. × (in the collection of author.) serpula triserrata. see notice, page × (in the collection of mr. rose.) vermicularia umbonata. pl. iii. fig. × mantell's geol. of sussex, tab. , fig. , page . (in the collections of mr. rose and author.) vermicularia elongata, bean ms. pl. iii. fig. , ^a × (in the collections of mr. bean, dr. bowerbank, and author.) cytherella ovata, roemer. pl. ii. fig. × jones, cretaceous entomostraca. pal. soc. page . (in the collection of mr. jones.) idmonea dilatata × d'orbigny's terrains crétacés, tab. . (in the collection of mr. bean.) diastopora ramosa, dixon × geol. suss. page . (in the collection of mr. bean.) ceriopora spongites × goldfuss, page , tab. , fig. . (in the collection of author.) terebratula capillata. pl. iv. fig. , ^a, mag. surface × davidson's cretaceous brachiopoda, plate , fig. , page . (in the collections of mr. rose and author.) terebratula biplicata. pl. iv. fig. , ^a, mag. surface × david. plate , fig. . (in the collections of dr. bowerbank, mr. rose, and author.) terebratula dutempleana × david. , fig. . (in the collection of mr. rose.) terebratula semiglobosa. pl. iv. fig. , ^a, mag. surface × × david. plate , fig. . (in the collections of dr. bowerbank, mr. bean, and author.) kingena lima. pl. iv. fig. , ^a, mag. surface × david. plate , fig. , page . (in the collections of mr. rose and author.) avicula, cast of. (in the collection of mr. bean.) × exogyra haliotoidea. pl. ii. fig. × sow. m. c. tab. , page . (in the collections of mr. rose and author.) inoceramus coquandianus. pl. i. fig. × d'orb. ter. crét. tab. , fig. - . (in the collection of author.) i. crispii. pl. i. fig. × mant. g. s. tab. , fig. , page . (in the collections of mr. rose and geol. soc.) i. tenuis. pl. i. fig. × ? mant. g. s. page . (in the collections of mr. rose and mr. wetherell.) i. gryphæoides × sow. m. c. tab. , fig. , page . (in the collection of mr. rose.) i. læviusculus, bean × (in the collection of mr. bean.) i. sulcatus × sow. m. c. tab. , page . (in the collection of mr. rose.) ostrea frons. park. pl. ii. fig. × sow. m. c. tab. , page . (in the collection of mr. wetherell.) o. vesicularis, lam. pl. ii. fig. × sow. m. c. tab. , page . (in the collection of the author.) o. normaniana × d'orb. tab. , fig. - , page . (in the collection of mr. rose.) pecten beaveri × sow. m. c. tab. , page . (in the collection of mr. rose.) spondylus latus × × sow. m. c. tab. , fig. , page . (in the collection of mr. rose and author.) ammonites alternatus ? × woodward, geol. norfolk, tab. , fig. . ammonites complanatus × sow. m. c. tab. , fig. . (in the collection of mr. rose.) a. rostratus × sow. m. c. tab. , page . (in the collection of mr. rose.) a. serratus, parkinson × sow. m. c. tab. , page . (in the collection of mr. rose.) belemnites attenuatus. pl. iv. fig. × sow. m. c. tab. , fig. , page . (in the collection of author.) b. minimus. pl. iv. fig. × × × sow. m. c. tab. , fig. , page . (in the collections of messrs. bowerbank, bean, rose, wetherell, and author.) belemnites listeri. pl. iv. fig. × phil. geol. york. tab. , fig. . (in the collection of author.) b. ultimus, d'orb. pl. iv. fig. × sharpe, chalk moll. tab. , fig. . (in the collections of mr. bean and author.) nautilus simplex. pl. i. fig. × × sow. m. c. tab. , page . (in the collections of mr. rose, mr. wetherell, and author.) otodus appendiculatus × ag. vol. iii., page , tab. . (in the collection of mr. wetherell.) tooth of saurian × (in the collection of mr. bean.) vertebra of polyptychodon (?) × (in the collection of author.) siphonia pyriformis is probably the head of spongia paradoxica. in the cabinet of mr. rose is a mass of the latter, to which a head similar to the one figured is attached. bourgueticrinus rugosus. the diameter of the specimen figured is / of an inch, the depth of each plate / . the surface of attachment is covered with very fine mamillæ, in rays of seven in number; a smaller specimen in possession of the author measures / of an inch in diameter and / in depth. the serpula represented in plate iii. fig. varies in its irregular growth from the specimens figured on the same plate. this character perhaps can scarcely be regarded as a specific difference; both v. elongata and the serpula under consideration have the same thickness of the calcareous tube. the former occurs only at speeton and the latter at hunstanton; in order to distinguish the two, the title "irregularis" may be applied to the latter as a variety. serpula triserrata, a species found on a specimen of ammonites complanatus, is distinguishable by its three serrate longitudinal ridges. a similar form occurs on ostreæ from the kimmeridge clay of west norfolk. terebratula semiglobosa is common at speeton, but very rare at hunstanton. t. biplicata is very common at hunstanton, but is not known at speeton. inoceramus læviusculus, bean, a large smooth species something like i. cuvieri. the ammonites alternatus of woodward is now lost; it was probably a variety of a. serratus, park. belemnites minimus is sometimes two inches long in the hunstanton cliff. the vertebra of polyptychodon would be, if perfect, about six inches in diameter and three in thickness. the small specimen shown in plate ii. fig. evidently belongs to the turbinolian family of corals, and possibly to the genus trochocyathus instituted by messrs. milne-edwards and j. haime, in . the specimens as yet obtained are not sufficiently numerous nor perfect for a rigid comparison with other forms, or to admit of a sufficiently detailed description should the species prove to be new. the constricted form of growth is very common in the parasmilia of the upper chalk, and has no specific value. the characteristic fossils of the red chalk at speeton are terebratula semiglobosa, belemnites minimus, and vermicularia elongata; and at hunstanton, terebratula biplicata, belemnites minimus, and spongia paradoxica. in conclusion, i have endeavoured all along to confine myself to facts, and to abstain from theories, because i think the geologists' association ought rather to follow in the steps of learned men than to wish to take the lead. i am sure by doing so we shall gain respect. if the strictly scientific workers see we wish to acquire information, rather than to purchase an empty name, they will hold out the right hand of fellowship and help us mightily; whilst, on the contrary, if they perceive we aspire too much, and attempt to grasp what we cannot hold, then well-merited ridicule will undoubtedly be ours. the geologists' association was only formed to bring amateurs together, to give them a place to meet in, and a room where they could speak on kindred subjects. i trust the members will always use the opportunity, and not be afraid to speak, ever remembering that each one has some little knowledge which his neighbour has not, and that when each helps his fellow, much must be the gain at last. [illustration: pl. i.] [illustration: pl. ii.] [illustration: pl. iii.] [illustration: pl. iv.] available on the internet archive and a physical copy of the book. the elements of geology; adapted to the use of schools and colleges. by justin r. loomis, professor of chemistry and geology in waterville college. with numerous illustrations. boston: gould and lincoln, washington street. entered according to act of congress, in the year , by gould & lincoln, in the clerk's office of the district court of the district of massachusetts. stereotyped by hobart & robbins, boston. press of g. c. rand, cornhill, boston. preface in preparing the following work, it was intended to present a systematic and somewhat complete statement of the principles of geology, within such limits that they may be thoroughly studied in the time usually allotted to this science. a sufficient number of leading facts has been introduced to enable the learner to feel that every important principle is a conclusion to which he has himself arrived; and yet, for the purpose of compression, that fullness of detail has been avoided with which more extended works abound. in furtherance of the same object, authorities are seldom cited. the consideration of geological changes is made a distinct chapter, subsequent to the one on the arrangement of materials. it should, however, be remembered that these processes of arranging and disturbing are not thus separated in time. in nature the two processes are always going on together. it seemed important to exhibit the science with as much unity and completeness as possible; and hence, discussions upon debatable points in theoretical geology, so interesting to mature geologists, would have been out of place here; and yet those more intricate subjects have not been omitted. a large proportion of the work is devoted to the explanation of geological phenomena, in order to convey an idea of the modes of investigation adopted, and the kind of evidence relied on. where diversities of opinion exist, that view has been selected which seemed most in harmony with the facts; and the connection has not often been interrupted to combat, or even to state, the antagonist view. technical terms have, in a few instances, been introduced, and principles referred to, which are subsequently explained. the index will, however, enable the student to understand them, without a separate glossary. some may prefer to commence with the second chapter, deferring the study of the elementary substances, minerals and rocks, to the last. such a course may be pursued without special inconvenience. questions have been added, for the convenience of those teachers who may prefer to conduct their recitations by this means. but, when the circumstances of the case admit of it, a much more complete knowledge of the subject will be acquired by pupils who are required to analyze the sections, and proceed with the recitation themselves; while the teacher has only to correct misapprehension, explain what may seem obscure, and introduce additional illustrations. list of illustrations. . columnar trap, new holland. (_dana._) . the four divisions of rocks, and their relative positions. _a_, volcanic rocks. _b_, granite. , , , , granite of different ages. _c_, metamorphic rocks. _d_, fossiliferous rocks. (_lyell._) . granite veins in slate, cape of good hope. (_hall._) . granite veins traversing granite. (_hitchcock._) . extinct volcanoes of auvergne. (_scrope._) . lava of different ages, auvergne. (_lyell._) . strata folded and compressed by upheaval of granite. . favosites gothlandica. . catenipora escharoides. (chain coral.) . caryocrinus ornatus. (_hall._) { leptæna alternate. orthis testudinaria. } . { }(_hall._) { delthyris niagarensis. } . section of a chambered shell, showing the chambers and the siphuncle. . orthoceras. . curved cephalopoda, _a_, ammonite; _b_, crioceras; _c_, scaphite; _d_, ancyloceras; _e_, hamite; _f_, baculite; _g_, turrilite. (_agassiz and gould._) . trilobite. . cephalaspis lyellii. (_agassiz._) . pterichthys oblongus. (_agassiz._) . fault in the coal formation, _a a_, layers of coal, _b b_, surface and soil. . stigmaria ficoides; newcastle. (_lindley and hutton._) . trunk of sigillaria. (_trimmer._) . bark of sigillaria. (natural size.) . sphenopteris crenata. (_lindley._) . pachypteris lanceolata. (_brongn._) . sigillaria levigata. (_brongn._) . lepidodendron sternbergii, bohemia. (_sternberg._) . calamite. . heterocercal fish. homocercal fish. . impressions of raindrops, wethersfield, conn. (_hitchcock._) . _b_, bird tracks in the conn. river sandstone, _a_, consecutive tracks; _c_, track of cheirotherium (probably a reptile), penn. and germany. . section in the isle of portland. (_buckland._) . apiocrinites rotundus, bradford, eng. (_miller._) . gryphea incurva. . _a_, outline of ichthyosaurus; _b_, plesiosaurus. . pterodactyle. . _a_, diploctenium cordatum; _b_, marsupites; _c_, salenia; _d_, galerites; _e_, micraster cor-anguinum. (_agassiz & gould._) . _b_, belemnite. _a_, restored outline of the animal to which it belonged. . cerithium intermedium. . murex alveolatus. . conus concinnus. . nummulite. . outline of paleotherium. . outline of anoplotherium. . skeleton of the mastodon. . univalve with entire mouth. . univalve with notched mouth. . unimuscular bivalve. . bimuscular bivalve. . parallel planes of cleavage intersecting curved strata. (_sedgwick._) . _a b_, a vein of segregation; _c d_, a dike. . faults and denuded strata. . vertical conglomerate. (_lyell._) . inclined strata in dorsetshire, england. (_buckland._) . dip of strata. . axes and valleys in disturbed strata. . curved strata of slate, berwickshire, eng. (_lyell._) . folded strata. . slope of mountains. . europe at the silurian epoch. (_guyot._) . europe at the tertiary epoch. . area of elevation and depression in the pacific and indian oceans. (_darwin._) . _c c_, coral wall. (_trimmer._) . _c c_, coral wall above the sea-level; _c' c'_, second coral wall. . coral wall after partial subsidence. . atoll. the coral wall only appearing. the original island entirely submerged. . remains of the temple of jupiter serapis, near naples. . detached hills of old red sandstone, rosshire, scotland. (_lyell._) . section of denuded strata, mass. (_hitchcock._) . grooved and striated surface of rocks. . artesian wells. . segregated masses in rocks. . columnar form taken by basalt on solidification. . layers of limestone now forming, san vignone, italy. (_lyell._) . erosion of rock by the action of the waves. . marine currents. . sediment deposited in horizontal layers. . section of greensand, bedfordshire, eng. (_lyell._) . glacier, with lateral and medial moraines, _a a_, terminal moraines. . iceberg. . volcanic eruption. (_trimmer._) . fractures produced by upheaval. . fossiliferous rock altered by contact with granite. . consecutive changes by which horizontal strata become vertical. table of contents. page chapter i. of the material which compose the crust of the earth. section i.--elementary substances, section ii.--simple minerals, section iii.--the mineral masses which form the crust of the earth, chapter ii. of the arrangement of the materials which compose the crust of the earth. section i.--the classification of rocks, section ii.--the plutonic rocks, section iii.--the volcanic rocks, section iv.--the non-fossiliferous stratified (or metamorphic) rocks, section v.--the fossiliferous rocks, section vi.--fossils, section vii.--the time necessary for the formation of the stratified rocks, chapter iii. of the changes to which the crust of the earth has been subjected. section i.--changes which have taken place at great depths below the surface, section ii.--changes in the mass of the stratified rocks, section iii.--changes of elevation and subsidence, section iv.--changes on the surface of the earth, section v.--changes of climate, section vi.--advantages resulting from geological changes, chapter iv. of the causes of geological phenomena. section i.--atmospheric causes, section ii.--chemical action, section iii.--organic causes, section iv.--aqueous causes, section v.--aqueo-glacial action, section vi.--igneous causes, chapter i. of the materials which compose the crust of the earth. section i.--elementary substances. there are about sixty substances known to the chemist which are considered as elementary; but most of them are rarely met with, and only in minute quantities. a few of them are, however, so abundant, in the composition of the crust of the earth, as to render some attention to them necessary. _oxygen_ is more widely diffused than any other substance. it is an ingredient of water and of the atmosphere, the former containing eighty-eight per cent., and the latter twenty-one. nearly all rocks contain oxygen in combination with the metallic and metalloid bases, and the average proportion of oxygen which they contain is about forty-five per cent.; so that it will not differ much from the truth to consider the oxygen in the earth's crust as equal in weight to all the other substances which enter into its composition. _hydrogen_ occurs in nature principally in combination with oxygen, forming water. it is also an ingredient in bitumen and bituminous coal. _nitrogen_ is confined almost entirely to the atmosphere, of which it forms four-fifths. it enters into the composition of some varieties of coal, and is sparingly diffused in most fossiliferous rocks. one of the most important substances in nature is _carbon_. it constitutes the principal part of all the varieties of coal, as well as of graphite, peat and bituminous matter. a much larger amount of carbon exists in the carbonic acid which is combined with the oxides of the metalloids and metals. the most abundant of these compounds is limestone, which contains about twelve per cent, of carbon. in the neighborhood of volcanoes _sulphur_ is found pure and in a crystalline form. it is a constant ingredient in volcanic rocks, and in several of the most important ores, particularly those of lead, copper and iron. the most abundant sulphate is gypsum, which contains twenty-six per cent, of sulphur. in small quantities it is widely diffused in rocks, and in the waters of the ocean. _chlorine_ is found principally as an ingredient of rock-salt, which contains sixty per cent, of it, and of sea-water, which contains one and a half per cent. _fluorine_ is found, though very sparingly, in nearly all the unstratified rocks. it forms nearly half of the mineral known as derbyshire spar. of the metals, _iron_ is the only one that is found abundantly. it enters into the composition of nearly all mineral substances. it is generally combined with oxygen, and occurs less frequently as a carbonate or sulphuret. of volcanic rocks it forms about twenty per cent. its ores are sometimes found in the form of dikes or seams, having been injected from below; at other times, in the form of nodules or stratified masses, like other rocks of mechanical origin. _manganese_ is likewise extensively diffused, but in very small quantity. the other metals are often met with, but their localities are of very limited extent. of the metallic bases of the earths and alkalies, _silicium_ is the most abundant. it generally occurs in the form of silex, which is an oxide of the metal. there are but few rocks in which it is not found in considerable amount. _aluminium_ generally occurs as an oxide, in which form it is alumina. it is the base of the different varieties of clay and clay-slate. it is also a constituent of felspar and mica. _potassium_ is an ingredient of felspar and mica, and hence is found in all the primary and in most of the volcanic rocks, as well as in the stratified rocks derived from them. _sodium_ is a constituent of a variety of felspar which is somewhat abundant in volcanic rocks. its principal source is the extensive beds of rock-salt, and the same substance in a state of solution in the waters of the ocean. _calcium_ constitutes about forty per cent, of limestone, and is an ingredient in nearly all igneous rocks. this metal, in the state of an oxide, is lime. _magnesium_ is somewhat abundant, but less so than calcium. it is one of the bases of dolomite and magnesian limestone, and is an ingredient of talc and all talcose rocks. the substances now enumerated constitute nearly the entire mineral mass of the crust of the earth. they may be arranged in the following order:-- i. non-metallic substances. oxygen. hydrogen. nitrogen. carbon. sulphur. chlorine. fluorine. ii. metals. iron. manganese. iii. metallic bases of the earths and alkalies. silicium. aluminium. potassium. sodium. calcium. magnesium. these substances, chemically combined, form _simple minerals_. section ii.--simple minerals. all substances found in the earth or upon its surface, which are not the products of art or of organic life, are regarded by the mineralogist as _simple minerals_. about four hundred mineral species are known, and the varieties are much more numerous; but only a small number of them are so abundant as to claim the attention of the geologist. an acquaintance with the following species is, however, necessary. _quartz_ is probably the most abundant mineral in nature. it is composed wholly of silex. its specific gravity is . . it is the hardest of the common minerals, gives sparks with steel, scratches glass, and breaks into irregular angular fragments under the hammer. when crystallized, its most common form is that of a six-sided prism, terminated by six-sided pyramids. when pure, it is transparent or translucent, and its lustre is highly vitreous. the transparent variety is called _rock crystal_. when purple, it is _amethyst_. when faint red, it is _rose quartz_. when its color is dark brown, or gray, and it has a conchoidal fracture, it is _flint_. when quartz occurs in white, tuberous masses, of a resinous lustre and conchoidal fracture, it is _opal_. the precious opal is distinguished by its lively play of colors. _jasper_ is opaque, and contains a small per cent, of oxide of iron, by which it is colored dull red, yellowish red or brown. the light-colored, massive, translucent variety is _chalcedony_. the flesh-colored specimens are _carnelian_. when composed of layers of chalcedony of different colors, it becomes _agate_. several of the varieties of quartz, such as amethyst, opal, carnelian and agate, are used to considerable extent in jewelry. _felspar_ is composed of silex, alumina and potassa. it resembles quartz, but it is not as hard, cleaves more readily, and is not generally transparent. its specific gravity is . . its lustre is feebly vitreous, but pearly on its cleavage faces. its color is sometimes green, but generally dull white, and often inclined to red or flesh-color. _mica_ is composed of the same ingredients as felspar, together with oxide of iron. its specific gravity is nearly three. it is often colorless, but frequently green, smoky, or black. it may be known by its capability of division into exceedingly thin, transparent, elastic plates. _hornblende_ is composed of silex, alumina and magnesia. its specific gravity is a little above three. its color is generally some shade of green. when dark green or black, whether in a massive or crystalline state, it is _common hornblende_. when light green, it is _actinolite_. the white variety is _tremolite_. when it is composed of flexible fibres, it is _asbestus_; and when the fibres have also a silky lustre, it is _amianthus_. _augite_ or _pyroxene_ has, till recently, been considered as a variety of hornblende. its specific gravity is slightly different; its composition is the same, and in general appearance it is not easily distinguished from hornblende. it has, however, been made a distinct species, because its crystalline form is different. _hypersthene_ is composed of silex, magnesia and oxide of iron. its specific gravity is . . it closely resembles hornblende. the lustre of its cleavage faces is metallic pearly. its color is grayish or greenish black. _talc_ is composed of silex and magnesia. its specific gravity is . . it resembles mica in its general appearance and in its lamellar structure, but it is easily distinguished from it by its plates being not elastic, and by its soapy feel. its color is generally some shade of green. _soapstone_ is an impure variety of talc, of a light gray color, earthy texture, and is unctuous to the touch. _chlorite_, another impure variety, is a dark green rock, massive, easily cut with a knife, and unctuous to the touch. _serpentine_ is composed of silex and magnesia. its specific gravity is . . it is generally massive, unctuous to the touch, and of a green color. it is often variegated with spots of green of different shades. with a mixture of carbonate of lime it forms the _verd antique marble_. _carbonate of lime_, or common limestone, is composed of carbonic acid and lime. its specific gravity is . . it presents a great variety of forms. in a crystalline state it is generally transparent, and when so, possesses the property of double refraction. it may be distinguished from every other common species by its rapid effervescence with acids. it readily cleaves parallel to all the faces of the primary form, which is a rhombohedron. _sulphate of lime_, or gypsum, is composed of sulphuric acid and lime. its specific gravity is . . when crystalline, it has a pearly lustre, is transparent, and goes under the name of _selenite_. _common gypsum_ resembles the other earthy limestones, but it is softer, and may be readily distinguished by its not effervescing with acids. to the minerals now enumerated may be added the following, which are of frequent occurrence, but not in great quantities; namely, carbonate of magnesia, oxide of iron, iron pyrites, rock-salt, coal, bitumen, schorl and garnet. these simple minerals, either in separate masses or mingled more or less intimately together, compose almost wholly the earth's crust. section iii.--the mineral masses which form the crust of the earth. that portion of the structure of the earth which is accessible to man is called the _crust of the earth_. the mineral masses which compose it, whether in a solid state, like granite and limestone, or in a yielding state, like beds of sand and clay, are called _rocks_. the _unstratified rocks_ are granite, hypersthene rock, limestone and serpentine, and the trappean and volcanic rocks. _granite_ is a rock of a light gray color, and is composed of quartz, felspar and mica, in variable proportions, confusedly crystallized together. the felspar is generally the predominant mineral. it is sometimes of a very coarse texture, the separate minerals occurring in masses of a foot or more in diameter. at other times it is so fine-grained that the constituent minerals can scarcely be recognized by the naked eye; and between these extremes there is every variety. the term granite is not, however, confined to an aggregate of these three minerals. in some instances the felspar so predominates as almost to exclude the other minerals, when it is called _felspathic granite_. when the quartz appears in the form of irregular and broken lines, somewhat resembling written characters, in a base of felspar, it is called _graphic granite_. when talc takes the place of mica, it is _talcose granite_. when hornblende takes the place of mica, it is _syenite_. granite or any rock becomes _porphyritic_ when it contains imbedded crystals of felspar. there is a rock of crystalline structure, like granite, but of a darker color, which is called _hypersthene rock_. it is composed of labrador felspar and hypersthene. the mineral species _serpentine_ and _limestone_ often occur unstratified in considerable quantities. _volcanic rocks_ consist of the materials ejected from the craters of volcanoes. they are composed of essentially the same minerals as trap rocks. when the material has been thrown out in a melted state, it is called _lava_. lava, at the time of its ejection, contains a large amount of watery vapor at a high temperature. under the immense pressure to which it is subjected in the volcanic foci, it may exist in the form of water; but when the lava is thrown out at the crater, the pressure cannot much exceed that of the atmosphere. the particles of water at once assume the gaseous form. as lava possesses considerable viscidity, the steam does not escape, but renders the upper portion of the mass vesicular. this vesicular lava is called _scoriæ_. by the movement of the stream of lava, these vesicles become drawn out into fine capillary tubes, converting the scoriæ into _pumice-stone_. a large part of the materials ejected from volcanoes is in the form of dust, cinders and angular fragments of rock. these soon become solidified, forming _volcanic tuff_, or _volcanic breccia_. in submarine eruptions these fragments are spread out by the water into strata, upon which other materials, not volcanic, are afterwards deposited. these interposed strata are called volcanic grits. the _trappean rocks_ are composed of felspar, mingled intimately and in small particles with augite or hornblende. they also contain iron and potassa. they are often _porphyritic_. when they contain spherical cavities, filled with some other mineral, such as chlorite, carbonate of lime or agate, they are called _amygdaloidal trap_. the principal varieties of trappean rock are basalt, green stone, and trachyte. in _basalt_, augite, or, in some cases, hornblende, is the predominant mineral. it is a heavy, close-grained rock, of a black or dark brown color. _greenstone_ differs from basalt in containing a much larger proportion of felspar. its structure is more granular, and frequently it assumes so much of the crystalline form as to pass insensibly into syenite or granite. it is a dark colored rock, with a slight tinge of green. both green stone and basalt are disposed to assume the columnar form, the columns being arranged at right angles to the faces of the fissure into which the trap is injected. when it is spread out into broad horizontal masses, the columns are vertical. (fig. .) _trachyte_ is composed principally of felspar, is of a grayish color, and rough to the touch. [illustration: fig. .] of the _stratified_ rocks the following are the most important: _gneiss_ is a rock closely resembling granite. it is an aggregate of the same minerals, but the proportion of mica is somewhat greater. the only distinction between them is that the gneiss is stratified, but the stratification is often so indistinct that it passes insensibly into granite. generally, however, the stratification is so distinct as to present a marked difference. _mica slate_ is such a modification of gneiss that the mica becomes the predominant mineral, with a small intermixture of quartz and felspar. consequently the stratification becomes very distinct, so as sometimes to render the mass divisible into thin sheets. the stratification is often wavy, and sometimes much contorted. _sandstone_ consists of grains or fragments of any other rock, but more frequently of siliceous rocks. the fragments are consolidated, sometimes without any visible cement, but often by a paste of argillaceous or calcareous substance. the color varies with that of the rock from which it was derived. generally, however, it is either drab or is colored red by oxide of iron. the fragments are sometimes so minute as scarcely to give the rock the appearance of sandstone. when they are of considerable size and rounded, the rock is called _conglomerate_. when they are angular, it is called _breccia_. _greensand_ is a friable mixture of siliceous and calcareous particles, colored by a slight intermixture of green earth or chlorite. _limestone_ is a very abundant rock, and occurs in many different forms. in transparent crystals it is _iceland spar_. when white and crystalline, it is _primary limestone_, _saccharine limestone_, or _statuary marble_. when sub-crystalline it is generally more or less colored. it is often _clouded_ with bands or patches of white in a ground of some dark color. when its texture is close, and the crystallization scarcely apparent, it is _compact limestone_. the white, earthy variety is chalk. a variety of limestone composed of small spheres is called _oölite_. _lias_ is the name given to an impure argillaceous variety of a brown or blue color. any rock which contains a considerable proportion of carbonate of lime, and which rapidly disintegrates on exposure to the atmosphere, is called _marl_. limestone sometimes contains carbonate of magnesia. it is then _magnesian limestone_, or _dolomite_. _clay_ consists of a mixture of siliceous and aluminous earth. it is tough, highly plastic, and generally of a lead blue color. it is always stratified, and often divided into very thin laminæ, which are separated by sprinklings of sand only sufficient to keep them distinct. _clay slate_, or _argillaceous schist_, is composed of the same materials as clay, and differs from it only in having become solidified. its color is gray, dark brown or black. in some beds it is purple. _shale_ is the same material in a state of partial solidification. on exposure to the weather, it soon disintegrates, and is finally reconverted into clay. all the varieties of argillaceous rock are easily distinguished by a peculiar odor which they emit when breathed upon. argillaceous slate sometimes takes into its composition portions of some other mineral, such as talc, mica, or hornblende. when any of these minerals becomes so abundant as to constitute a considerable part of the mass, the rock becomes _talcose_, _micaceous_, or _hornblende slate_. sometimes this last variety loses all appearance of a fissile structure, and is composed almost wholly of hornblende. it is then called _hornblende rock_. _diluvium_ is the name applied to masses of sand, gravel, and large rocks, called boulders, heaped confusedly together on the surface of the earth. it is also called _drift_. chapter ii. of the arrangement of the materials which compose the crust of the earth. section i.--the classification of rocks. in the first place, we divide rocks into _stratified_ and _unstratified_. this division is one which will in general be easily recognized, even by the most inexperienced observer; and the distinction is important, because it separates the rocks of igneous origin from those which have been produced by deposition of sediment from water. it will be shown hereafter that a part of the unstratified rocks have been formed at or near the surface of the earth; that is, they have taken their present form by passing from a state of fusion to a solid state above or between the stratified rocks, as in the case of lava (fig. , a). the other unstratified rocks have cooled so as to take the solid form below the stratified rocks, as at b. the first are called _epigene_, or _volcanic rocks_; the last, _hypogene_, or _plutonic rocks_. the lowest portion of the second division, the stratified rocks, are termed _non-fossiliferous_, from the fact that they contain no evidence of the existence of organic beings at the time when they were deposited. their relation to the other rocks is shown at c. it is supposed that these rocks have been subjected to great changes by heat from the igneous rocks below them. on this account mr. lyell proposes to call them _metamorphic rocks_. the other portions of the stratified rocks are _fossiliferous_, containing the remains of organic beings which lived at the period when the rocks were deposited. they are represented at d. the division of the last-named rocks info groups will be given hereafter. [illustration: fig. .] we have then four principal classes of rocks: _plutonic rocks_, _volcanic rocks_, _non-fossiliferous stratified rocks_ and _fossiliferous rocks_. section ii.--the plutonic rocks. granite is by far the most important of this class of rocks. of its thickness no estimate can be made, as no mining operations have ever penetrated through it, and none of the most extensive displacements of rocks by natural causes has brought to the surface any other rock on which it rests. it may, therefore, be considered the foundation rock, the skeleton of the earth, upon which all the other formations are supported. the whole amount of granite in the earth's crust may be greater than that of all other rocks, but it comes up through the other formations so as to be exposed over only a comparatively small portion of the surface, and this is generally the central portion of mountain ranges, or the highest parts of broken, hill country. still, it is not unfrequently found in the more level regions, in the form of slightly elevated ridges, with the stratified rocks reclining against it. the structure of granite seems frequently to be a confused mixture of the minerals which compose it, without any approach to order in their arrangement; but in many cases it is found to split freely in certain directions, and to work with difficulty in any other. this may result from an arrangement of the integrant crystals, so that their cleavage planes approach more or less nearly to parallelism. when this is the case with the mica or felspar, it must diminish the cohesion in a direction perpendicular to these planes, and thus facilitate the cleavage of the mass. [illustration: fig. .] granite is found to penetrate the stratified rocks in the form of veins. the following section (fig. ) will show the relation of granite veins to the granitic mass below. the granite which is quarried for architectural purposes is often in comparatively small quantities, disappearing at the distance of a few hundred yards beneath the stratified rock; or else it exists in the form of isolated dome-shaped masses. it is probable that, if they could be followed sufficiently far, they would be found to be portions of dikes coming from the general mass of granite below. even the granite nuclei of the great mountain ranges may be considered as injected dikes of enormous magnitude. [illustration: fig. .] granite is itself intersected with granite veins more frequently, perhaps, than any other rocks; but the vein is a coarser granite than the rock which it divides. it is not uncommon to find one set of dikes intercepted and cut off by a second set, and the second by a third. the substance of the dikes was, of course, in a liquid state when it was injected, and the first must have become solid before the second was thrown in; hence the dikes are of different ages. the dikes _a b c_, represented in fig. , must have been injected in the order in which they are lettered. it is probable that, by the process of cooling, the liquid mass from which these dikes have proceeded has been gradually solidifying from the surface downwards. if so, it would follow that the granite nearest the surface ( , fig. ) is the oldest, and the newest is that which is at the greatest distance below ( ). it is possible that at great depths granite may be still forming, that is, taking the solid form, though of this there can be no direct proof. there is, however, proof that it has been liquid at periods of time very distant from each other; for the dikes sometimes reach to the top of the coal formation (for example), and then spread themselves out horizontally, as at _a_, showing that the rock above the coal had not then been deposited. another dike will extend through the new red sandstone, as at _b_, and spread itself out horizontally as before. these horizontal layers of granite, by their position in strata whose ages are known, indicate the periods when granite has existed in a liquid state. granite veins have been discovered in the pyrenees as recent as the close of the cretaceous period, and in the andes they have been found among the tertiary rocks. there are several other rocks, of minor importance, often found in connection with granite. hypersthene rock, in a few cases, forms the principal part of mountain masses. greenstone is more frequently associated with the trappean rocks, but it sometimes passes imperceptibly into syenite and common granite. limestone is found in considerable abundance, and serpentine in small quantities, as primary rocks, and have evidently been formed like granite, by solidifying from a state of fusion. section iii.--the volcanic rocks. the volcanic rocks consist of materials ejected from volcanoes. they are, however, ejected in very _different states_; sometimes as dust, sand, angular fragments of rock, cinders, &c., and sometimes as lava streams. in some instances, the lava has so little fluidity that it accumulates in a dome-shaped mass over the orifice of eruption, and perhaps in a few instances it has been thrust upward in a solid state. there are _two principal varieties_ of lava, the trachytic, consisting mostly of felspar, and the basaltic, consisting of hornblende. when both kinds are products of the same eruption, the trachytic lava is thrown out first, and the basaltic last. the reason of this is, that felspar is lighter than hornblende, and probably rises to the surface of the lava mass at the volcanic focus, and the basaltic lava is therefore reserved till the trachytic has been thrown off. these, like other rocks, have been produced at different epochs. there is, however, great difficulty in determining their age; there are some differences of structure and composition observed, in comparing the older and newer lavas; but the only method that can be relied on to determine their age is their relation to other rocks. when they occur between strata whose age is determined by imbedded fossils, they must be of intermediate age between the inferior and superior strata. . _modern volcanic rocks._--some of the volcanic rocks are of modern origin, and are produced by volcanoes now active. the total amount of these, and of all the other volcanic rocks, is probably less than that of either of the other principal divisions of rocks; yet they form no inconsiderable part of the earth's crust. the number of active volcanoes is not far from three hundred, and the number of eruptions annually is estimated at about twenty. in some cases, the lava consists of only a single stream, of but a few hundred yards in extent. it extends, however, not unfrequently twenty miles in length, and two or three hundred yards in breadth. the eruption of mount loa, on the island of hawaii, in , from the crater of kilauea, covered an area of fifteen square miles to the depth of twelve feet; and another eruption of the same mountain, in , covered an area of at least fifty square miles. the eruption in iceland, in , continued in almost incessant activity for a year, and sent off two streams in opposite directions, which reached a distance of fifty miles in one case, and of forty in the other, with a width varying from three to fifteen miles, and with an average depth of more than a hundred feet. the size of some of the volcanic mountains will also assist in forming an idea of the amount of volcanic rocks. monte nuovo, near naples, which is a mile and a half in circumference and four hundred and forty feet high, was thrown up in a single day. Ætna, which is eleven thousand feet high, and eighty-seven miles in circumference at its base, has probably been produced wholly by its own eruptions. a large part of the chain of the andes consists of volcanic rock, but the proportion we have not the means of estimating. . _tertiary lavas._--there is another class of volcanic products, which are so situated with reference to the tertiary strata that they must be referred to that period. the principal localities of these lavas, so far as yet known, are italy, spain, central france, hungary, and germany. they are also found in south america. those of central france have been studied with the most care. they occur in several groups, but they were the seats of volcanic activity during the same epoch, and formed parts of one extensive volcanic region. each of these minor areas, embracing a circle of twenty or thirty miles in diameter, is covered with hills two or three thousand feet in height, which are composed entirely of volcanic products, like the cone of Ætna. on many of them there are perfectly-formed craters still remaining. numerous streams of lava have flowed from these craters, some of which can now be traced, throughout their whole extent, with as much certainty as if they were eruptions of the present century. some of the lavas have accumulated around the orifices of eruption, forming rounded, dome-shaped eminences. these lavas generally consist of trachyte, and have therefore a low specific gravity, and imperfect fluidity. the basaltic lavas have often spread out over broad areas, and, when they have been confined in valleys, have reached a distance of fifteen miles or more from their source. there still remain indications of a current of lava which was thirty miles long, six broad, and in a part of its course from four to six hundred feet deep. the above sketch (fig. ) will give some idea of the highly volcanic aspect which the district of auvergne, in france, presents. [illustration: fig. .] the unimpaired state of some of the cones and craters, and of the lava currents, would lead to the impression that these regions have been the theatre of intense volcanic action within a very recent period. but there is good reason to believe that this has not been the case. "the high antiquity of the most modern of these volcanoes is indeed sufficiently obvious. had any of them been in a state of activity in the age of julius cæsar, that general, who encamped upon the plains of auvergne and laid siege to its principal city, could hardly have failed to notice them." it is equally certain that the commencement of their activity was at a late period in the history of the earth. lava currents are frequently found in france resting upon the early tertiary strata, but no lava current is found below them. the later tertiary strata contain pebbles of volcanic rocks, showing that lavas had been previously ejected, but none are found in the older strata of this formation. we must, therefore, conclude that these volcanic tracts assumed their volcanic character at some intermediate point in the tertiary period. when we find that their activity commenced at so late a period and closed so long ago, we might be led to suppose that it was of very short duration. but a great number of facts, in the present condition of the country, require that we should assign to them a very prolonged activity. a single instance will be sufficient to show the nature of the evidence upon which this conclusion rests. the heavy line (fig. ) represents the present form of one of the valleys. a bed of lava forms the highest point of land represented, and a second bed is found in an intermediate part of the slope. the position of the upper bed must have been a valley, when the lava flowed there. we may represent this valley by the line _a b c_. the slow operation of natural denuding causes at length excavated the valley _d e h_, when another lava current flowed through it, covering its bed of pebbles, as before. the same denuding causes have at length produced the present valley, _f g h_. these remnants of lava-currents, as they have formed a very imperishable rock, have protected the subjacent strata from erosion, and furnish evidence of the position of the valley at different periods. when we consider with what extreme slowness denuding causes produce changes on the surface, and what extensive changes they have here nevertheless effected in the interval between the production of the different lava currents, we are compelled to feel that that interval was a very prolonged one. yet this period, however long it may have been, was evidently less than the period of activity of these volcanoes. [illustration: fig. .] . _volcanic rocks of an earlier date_ are also found, sometimes as distinct lavas, though generally as volcanic grits. they occur interstratified with the cretaceous rocks, and with every other formation of the fossiliferous series, showing that, from the earliest times, these rocks have been accumulating as they now are. _the trappean rocks_ may, in a general classification, be considered as volcanic. it will be shown, hereafter, that they are the lavas of submarine volcanoes. they do not, however, occur in the form of lava currents, but in great tabular masses, generally between stratified rocks, or in the form of dikes. they are also entirely unconnected with cones or craters. the trappean rocks occur more or less abundantly in all countries. one of the most noted localities of this rock is a region embracing the north of ireland, and several of the islands on the western coast of scotland. it contains the celebrated giant's causeway, which consists of a mass of columnar trap; also fingal's cave, which is produced by a portion of the trap being columnar, and thus disintegrating more rapidly than the rest, by the action of the waves. an immense mass of greenstone trap, which has generally been considered as a vast dike, though often a mile in thickness, is found extending from new haven to northampton, on the west side of the connecticut river. it then crosses to the east side, and continues in a northerly direction to the massachusetts line. under different names, it constitutes a nearly continuous and precipitous mountain range for about one hundred miles. dr. hitchcock supposes this greenstone range to be, not an injected dike, but a tabular mass of ancient lava, which was spread out on the bed of the ocean during the period of the deposition of the connecticut river sandstone. it was subsequently covered with a deposit of strata of great thickness, and then by subterranean forces thrown into its present inclined position. there is a mass of basaltic rock in the valley of the columbia river, in the oregon territory, which extends without interruption for a distance of four hundred miles. its breadth and thickness is not known, but in some places the river has cut a channel in this rock to a depth of four hundred feet. its age has not been determined, and it will, perhaps, be found to be a tertiary or modern production. section iv.--the non-fossiliferous stratified (or metamorphic) rocks. . _gneiss_ is the most abundant rock in this class, and is generally found reposing on granite. its stratification is sometimes very distinct, but it is often so imperfect that it can scarcely be recognized. this is more frequently the case in the vicinity of granite on which it rests, and into which it insensibly passes. a large part of the material used for building purposes, under the name of granite, is obscurely marked gneiss. in all primary countries it is an abundant rock, occupying extensive districts, and sometimes forming mountain masses. . _mica slate_ lies next above gneiss, and is a very abundant rock. as it differs from gneiss only in the proportion of mica which it contains, and as the quantity of mica in it is very different in different places, it is often difficult to make the distinction between them. it also passes by insensible degrees into the argillaceous rocks. many of the argillaceous rocks are found, upon close examination, to contain mica in minute scales in such abundance as to make it doubtful whether they ought not to be regarded as mica slates; that is, the metamorphic action by which argillaceous slate is converted into mica slate had proceeded so far, before it was arrested, that it becomes impossible to say whether the argillaceous or micaceous characters predominate. . _argillaceous slate._--the last rock of this series is a slaty rock, more or less highly argillaceous. it does not differ in lithological characters from the same rock in the higher strata. it is doubtful whether the roofing-slates should be considered as belonging to the metamorphic series or not. they have been subjected to a very high degree of metamorphic action, and yet strata intimately associated with them have, in occasional instances, contained fossils. it is not easy to fix the exact upper limit of this series. the fossils are few, obscure, and seldom met with in the lowest fossiliferous series; and the transition is very gradual from the distinctly metamorphic to the fossiliferous rocks. this renders it impossible always to determine accurately the line of separation. the gneiss, mica slate and argillaceous slate, have the order of superposition in which they are here named. they differ only in the amount of metamorphic action to which they have been subjected; and the gneiss which is most highly metamorphic has, by being the lowest, been most acted upon,--the mica slate less, and the argillaceous slate least. in a particular locality, however, the lowest rock which was subjected to these causes of change, instead of having been of such a character as to produce gneiss, may have been a limestone, and in that case the lowest metamorphic rock would be a saccharine marble. in another locality the lowest rock may have been a sandstone, which would be converted into quartz rock. hence there may occur, in any part of the metamorphic series, crystalline limestone, quartz rock, hornblende slate, chlorite slate, and talcose slate; and any one of these rocks may be as abundant in any particular region, as gneiss, mica slate or argillaceous slate, is in another. the metamorphic rocks occur in all countries where there has been any considerable amount of volcanic action, and their total amount is very great; but their stratification is so confused and contorted, their superposition so irregular, and denudations have been so extensive, that no estimate can be made of their thickness. they are, perhaps, equal to all the other stratified rocks. section v.--the fossiliferous rocks. the fossiliferous rocks are divided into seven systems, which are readily distinguished by the order of superposition, lithological characters and organic remains. these systems are the silurian, the old red sandstone, the carboniferous, the new red sandstone, the oölitic, the cretaceous, and the tertiary systems. there is also an eighth system now in process of formation. it is the opinion of some geologists that there is another system situated between the metamorphic rocks and the silurian system. it has been called by dr. emmons, who has studied it with much care, the "taconic system," the taconic mountains, in the western part of massachusetts, being composed of these rocks. it is the lower part of what has been called, in england and wales, the _cambrian system_. the strata of this system have a nearly vertical position, and consist principally of black, greenish and purple slates, of great thickness. granular quartz rock, however, occurs in considerable quantity, and in this country two thick and important beds of limestone are found. these limestones are occasionally white and crystalline. generally, however, as a mass, they are a dark, nearly black rock, with a network of lines of a lighter color. all the clouded marbles for architectural and ornamental purposes are from these beds, and our roofing and writing slates are all obtained from the argillaceous portion of this system. the number of species of organic remains contained in this system is very small, and these, so far as discovered, belong to the annelida, with a few doubtful cases of mollusca. this system of rocks is found coming to the surface in a large part of new england, and the eastern part of new york, also in the western part of england and wales. those geologists who deny the existence of this system consider these rocks as parts of the silurian system which have been most disturbed by subterranean forces, and most altered by proximity to igneous rocks. the annexed sketch (fig. ) will exhibit the relations here referred to. certain portions of the silurian rocks are supposed to have been thrown into folds by the upheaval of the primary rocks. the plications nearest to the intrusive granite would be most altered. that part of the figure below the line _a a_ represents the outcropping edges as they now appear, the upper portion of the folds having been removed by some abrading cause. [illustration: fig. .] as it is yet uncertain which of these views is correct, convenience will justify us in retaining the name of cambrian system till further investigations shall settle the question. . _the silurian system._--the following tabular arrangement exhibits the divisions of the system as recognized in england, in new york, in pennsylvania and virginia, and in ohio. key to divisions ---------------- c - cambrian rocks. s - silurian system. d - devonian. ch - champlain division. on - ontario division. he - helderberg division. er - erie division. divisions as recognized divisions as recognized pennsylvania ohio. by english authors. by the new york and virginia. geologists. /-------------------\ /-----------------------\ /----------\ /--------\ { upper cambrian { { potsdam sandstone. } no. . { { { c { rocks, of sedgwick{ { calciferous sandrock. } { { { birdseye limestone. } no. . } { (probably). {ch{ trenton limestone. } } blue { { } limestone { llandeilo flags. { { utica slate. } } and marl. { { { } no. . } { { hudson river group. } { { { { { gray sandstone. } no. . { { { oneida conglomerate. } { {on{ { caradoc sandstone.{ { medina sandstone. } no. . { { { clinton group. } { { niagara group. { { } } { { { oneida salt group. } : { { { water-lime group. } : { { { pentamerus limestone. } no. . : { { { delthyris shaly } : { { { limestone. } : s { { { encrinal limestone. } : cliff { wenlock rocks. {he{ upper pentamerus } : { { { limestone. : limestone. { { { oriskany sandstone. } : { { { } no. . : { { { cauda-galli grit. } : { { { schoharie grit. } : { { { onondaga limestone. wanting. : { { { corniferous limestone. wanting. } { } { { { marcellus shales. } } black { { { hamilton group. } } slate. { upper and lower { { } no. . { { { tully limestone. } { ludlow rocks and {er{ } : { { genesee slate. d : the devonian { { } : { { portage group. } no. . } waver : system. { { } } { { {chemung group. } } sandstone. this name, _silurian_, was first used to designate the lowest well-characterized fossiliferous rocks in england. but it is now used to embrace the whole system as it occurs elsewhere. it is well exhibited in new york, both in consequence of its great development there, and because the whole system is only slightly acted upon by disturbing forces, so that the outcropping edge of each division extends over a large surface. this system is of great thickness, amounting, in places where it is well developed, to twenty thousand feet. the champlain division commences with a quartzose sandstone, passing gradually into limestone, which is succeeded by a very thick argillaceous deposit, the utica slate and hudson river group. the ontario division in the lower part is a mass of sandstone. above this is the clinton group, consisting of shales and sandstones. the most important part of this group, in an economical point of view, is a fossiliferous, argillaceous iron ore, coextensive with the group in this country, and is worked to supply a large number of furnaces. the last of the division is the niagara group, which commences with a mass of shale, and becoming at length calcareous, it terminates in a firm compact limestone. this limestone has withstood the action of denuding causes better than the shales either above or below it. it therefore presents a bold escarpment at its outcrop, and occasions waterfalls wherever streams of water cross it. the falls of niagara are formed by this rock. the niagara limestone, in its extension westward, becomes the lead-bearing rock of missouri, iowa and wisconsin. the helderberg division is a succession of highly fossiliferous limestones, with the intervention of only occasional beds of grits and shales. one member of the series is the onondaga salt group. the water obtained from this group in new york annually furnishes immense quantities of salt. the erie division consists of a thick mass of shales and sandstones. [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] the fossils of this system are very numerous, but consist mostly of the lower forms of animal life. _corals_ (figs. and ) are abundant, and constitute in some places a large proportion of the limestones. the _crinoidea_, or lily-shaped animals, consist of a jointed stem permanently attached, and bearing at the free extremity of the stem an expanded portion, which is the pelvis, or digestive cavity. the mouth is surrounded with a series of leaf-like tentacula, which serve the purpose of seizing and holding food. fig. represents the pelvis of one of the silurian fossils. the general character of the animal is better represented by fig. . the most abundant fossils of this period are the lowest orders of _bivalve mollusca_ (fig. ). the _cephalopoda_ are characterized by having the organs of locomotion attached to the head. the shell of several species is peculiar in being divided into distinct cells, or chambers (fig. , _b d_), perforated by a tube (siphuncle _a_). these fossil shells are sometimes straight, as the _orthoceras_ (fig. ), or curved, as shown in the several forms of fig. . the _trilobite_ was an articulated, crustaceous animal, having two lines along the back dividing it into three lobes, from which circumstance its name is derived. it is found in great numbers in the silurian rocks (fig. ). in a few instances remains of fishes have been found, but they by no means characterize the system. [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] the geographical range of this system is probably greater than that of any system of rocks above it. it is found occupying a large part of the territory west of the alleghany mountains, from canada, through new york, and the other states, to alabama; and extending westward to and beyond the mississippi river. it occupies a large district in the west of england, and is found in great force in the north and east of europe. . _the old red sandstone._--this formation consists almost entirely of a sandstone of a red color. it admits of division into three parts, though the characters vary in different places. the lowest is a thin-bedded argillaceous sandstone, consisting of finely levigated material, and easily splitting into thin sheets. from this circumstance it has received the name of _tilestone_. the middle portion is composed of nodules or concretions of limestone imbedded in a paste of red sand and shale. this has been called by english geologists, _cornstone_, and though very partially developed in some regions where the system is found, it is yet a very persistent member. the highest member of this formation is a mass of red sandstone, often passing into a coarse _conglomerate_. in england the thickness of the old red sandstone is not less than ten thousand feet. in this country it is scarcely three thousand feet. [illustration: fig. .] the fossils of this system are a few shells, a small number of vegetable species, and in particular localities the remains of fishes in great abundance. the system is characterized principally by fossils of this last kind. the fishes of this system have a cartilaginous skeleton, but are covered with plates of bone, which were faced externally with enamel. the jaws, which consisted of solid bone, were not covered with integument. the exterior bony covering seems to have been the true skeleton, as is, in part, the case with the tortoise. in some of the fishes of this period there is a wing-like expansion on each side of the neck, which has given them the name of _pterychthis_ (fig. ). in others, as the _cephalaspis_, the plate of bone on the back is so large as to cover nearly the whole body, and make it resemble a trilobite (fig. ). this system has an extensive geographical range. in england, it occupies a band of several miles in width, extending from the welsh border northward through scotland to the orkney islands. in this country, it forms the catskill mountains, in new york, and extends south and west so as to underlie the coal-fields of pennsylvania and virginia. . _the carboniferous system._--this system consists of three parts, distinguished by lithological and fossil characters. the _carboniferous limestone_ is a dark-colored, compact limestone, forming the base of the system, and reposing on the old red sandstone. its thickness is from six hundred to one thousand feet, often with scarcely any intermixture of other rock; but it sometimes loses its character of a limestone, and becomes a sandstone, or conglomerate. it generally contains the ores of lead in considerable quantity, and from this circumstance has been called _metalliferous limestone_. in england it is the principal repository of these ores. in the western states it is the upper portion of the lead-bearing strata. [illustration: fig. .] the fossils are marine, and very numerous. corals and crinoidea are very abundant. the crinoidea, in some localities, form so large a part of the rock as to have given to it the name of encrinal limestone. the orthoceras and trilobite are found, but become extinct with this formation. several species of bivalves, such as delthyris and leptæna, are also common. next above the limestone lies the sandstone, sometimes called _millstone grit_. it is generally drab-colored, but occasionally red. its thickness is often equal to that of the limestone. sometimes it is fine-grained and compact; but generally it is coarse-grained, and often passes into a conglomerate. it contains but few fossils, and those of vegetable origin. the highest part of the system is the _coal measures_. they consist of beds of sandstone, limestone, shale, clay, ironstone and coal, occurring without much uniformity in their order of superposition. the coal measures have a thickness of about three thousand feet. the sandstones and limestones are not distinguishable from the sandstones and limestones in the lower part of the system. the ironstone either occurs in concretionary nodules, often formed around some organic nucleus, or it is an argillaceous ore, having a slaty structure. in either case, it consists of subordinate beds in the shale. the coal consists of several beds distributed through the measures. the beds vary in thickness from a few lines or inches to several feet. in a few cases beds have been found measuring fifty or sixty feet in thickness. the workable beds are ordinarily from three to six feet thick. [illustration: fig. .] the carboniferous formation is very much disturbed by dikes, faults (fig. ; see also fig. ), and other dislocations. the amount of change of position in the strata, by faults, is very various; frequently but a few feet. in one case in england there is a fault of nearly a thousand feet. there is a case of dislocation in belgium where the strata are bent into the form of the letter z, so that a perpendicular shaft would cut through the same bed of coal several times. the characters and order of superposition which have now been given may be regarded as the general type of the carboniferous formation. there are, however, several important modifications. . beds of coal sometimes alternate with beds of millstone grit. thus, in scotland and in the north of england, this intermediate member of the system disappears, or, rather, is incorporated with the coal measures. the same is true, to considerable extent, in this country. . sometimes the carboniferous limestone also disappears as a distinct member of the system, partly by becoming arenaceous, and partly by the intercalation of beds of coal. in this last case, the whole formation from the old to the new red sandstone becomes a series of coal measures. in this country the carboniferous limestone is found very generally to underlie the coal strata. . the fractures and faults, which were formerly supposed to be characteristic of the coal formation, are seldom found in the great coal-fields of this country, except in those of the anthracite coal of pennsylvania; and even there they are much less common than in the coal-fields of europe. there are three principal varieties of coal, distinguished by the different proportions of bitumen which they contain. the common bituminous coal kindles readily, emits much smoke, and throws out so much liquid bitumen that the whole soon cakes into a solid mass. it contains about forty per cent, of bitumen. the second kind, or cannel coal, contains twenty per cent., and inflames easily, but does not agglutinate. the stone-coal, or anthracite, contains scarcely any bitumen, ignites with difficulty, emits but little smoke, and produces a very intense heat. the bituminous varieties are always found in the least disturbed portions of the coal districts; and the anthracite is found in the more broken and convulsed portions, where we may suppose that the subterranean heat has been sufficient to drive off the volatile bituminous part, and reduce it to the anthracite form. hence the eastern pennsylvania coal-fields, which lie near the principal axes of elevation of the appalachian mountains, furnish only anthracite; while the same coal-seams, in their extension to the western part of the state, are bituminous. where coal is quarried in large quantity, a shaft is sunk through the overlying strata to the coal-beds, and the coal is raised to 'the surface by steam power. after the coal has been quarried to some distance from the shaft, pillars of unquarried coal are left to support the overlying strata. fatal accidents have sometimes occurred by the giving away of these supports. over a large part of the coal-fields of the united states it has not yet become necessary to sink shafts. the quarrying is commenced at the outcrop of the coal-bed; and, till the cover becomes of considerable thickness, it has been found economical to "strip" off the overlying rock, rather than to work a subterranean gallery. brine-springs are often found in the coal measures of sufficient strength to be used in the manufacture of salt. this is now done to considerable extent in ohio. in the valley of the kenhawa river, kentucky, the rocks of which belong to the carboniferous system, the brine is nearly saturated with salt; and in some of the borings they have even discovered beds of rock-salt of great thickness and purity. there is no other part of the geological series so obviously connected with national prosperity as the coal formation. while a country is new, the forests furnish an abundant supply of fuel; but in the course of a few years these are consumed. this country will soon be principally dependent upon its coal-mines for fuel, even for domestic purposes; and, in carrying on the great branches of national industry, such as the smelting and working of iron, and in the formation of steam for the purposes of manufacture and transportation, we are already mainly dependent upon mineral coal. a nation which does not possess an abundant supply of this mineral, _or which does not use it_, cannot long maintain a high degree of national prosperity. in these inexhaustible masses of coal, accumulated ages before the existence of the human race, is a most obvious prospective arrangement for securing our happiness and improvement. and this arrangement embraces not only the accumulation of a combustible material in such abundance, but also its juxtaposition with an equally inexhaustible accumulation of iron ore, and the limestone which is necessary as a flux in the reduction of the ore. so bulky and heavy materials as coal and iron ore could neither of them have been transported to any considerable distance for the manufacture of iron; and without the manufacture of iron on a large scale, the present operations in manufactures and transportation could never have been entered upon. a large proportion of the iron furnaces in this country, and nearly all of them in great britain, employ mineral coal for fuel, and obtain their ore from the beds contained in the coal measures. the fossils of the coal measures are almost entirely of vegetable origin, and are very abundant. they are seldom found in the coal-beds, but in the strata of shale immediately above or below the solid coal. [illustration: fig. .] the _stigmaria_ (fig. ) is found most abundantly, and in a large proportion of cases to the exclusion of every other form, in the lower shales. it consisted of a large dome-shaped mass, often three or four feet in diameter, with trailing branches, or roots, spreading off horizontally to a distance of twenty feet. in a few instances tree ferns have been found, petrified in a horizontal position, and being apparently a mere continuation of the stigmaria. hence the stigmaria has been supposed to be the base of the tall tree ferns, the leaves of which so abound in the upper shales. if this is not the case, there are no forms of the existing flora of the earth analogous to the stigmaria. it is always found in connection with the coal-beds of the carboniferous formation, and never with the coal-beds which sometimes occur in the later formations. [illustration: fig. .] [illustration: fig. .] the tree ferns (fig. ) attained a height of fifty or sixty feet, and a diameter of four feet. they have received the name of _sigillaria_ in consequence of the seal-like impressions (fig. ) with which the surface is covered, and which are the scars left where the fronds have fallen off. these fronds (fern leaves) are the most abundant fossil of the series. they are distinguished by some peculiarity in form, as the sphenopteris (wedge-shaped fern leaf), pachypteris (thick fern leaf), &c. (figs. and .) [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] there was another kind of sigillaria (fig. ), in which the surface was fluted, and the markings are superficial, and occur on the ridges. it reached as great a size as the tree ferns, but to what general class of plants it belonged is still doubtful. the _lepidodendron_ (scale-covered tree) (fig. ) is the fossil which most nearly resembled in general appearance our present forest trees. specimens are found four feet in diameter and seventy feet in height. in botanical characters it resembled, in some respects, the trailing club-mosses, while in others it was very similar to the norfolk island pine. [illustration: fig. .] the _calamite_ (fig. ) was a plant resembling, in its jointed and striated surface, the equisetum (rush), but was sometimes twelve inches in diameter. the carboniferous formation exists more or less abundantly in all the great divisions of the earth. it occurs in nearly all of the countries of europe. the largest deposits known are, however, in the united states; especially in the states of pennsylvania and virginia, and in ohio. . _the new red sandstone._--the lower division of this formation, called the permian system, consists of a thick mass of sandstones, generally of a red color, with occasional alternations of argillaceous rock, succeeded by a series of magnesian limestones. the upper division, or triassic system, is composed of a red conglomerate, a limestone which has received the name of muschelkalk (shelly limestone), and a series of variegated marls and sandstones. the ores of copper are found, to considerable extent, in this formation. the rich copper mines of germany are in the magnesian limestone, or, as it is there called, zechstein (minestone). the lake superior copper mines occur in a red sandstone formation, which will probably be found to belong to this system. the salt-beds, salt springs, and beds of gypsum, are so, generally found in this rock in england, that it has been called by the english geologists the "saliferous system." it is, however, found that in other countries these minerals occur in equal abundance in formations of an earlier and later date. [illustration: fig. .] the fossils of this system are not abundant. in the permian portion, impressions of fishes are found, always with the peculiarity that the tail is _heterocercal_ (fig. ); that is, with the spine continued into the upper lobe. the same peculiarity prevails in the carboniferous and all the earlier formations. fishes with the tail _homocercal_ begin to appear in the triassic portion of this system, and are found in all the subsequent formations. the remains of saurians also occur in this formation. [illustration: fig. .] the red sandstones seem to have been better adapted to retain the forms which were impressed upon them than to preserve the organic remains which were deposited in them. hence, while they contain but few fossils, the strata are often covered with ripple marks, with sun cracks, occasioned by contraction while drying, or with depressions produced by rain-drops, and the pits are sometimes so perfect as to show the direction of the wind when the drops fell. (fig. .) the tracks of animals are also well preserved. some of them were produced by reptiles (fig. , _c_), and some probably by marsupial animals, but most of them by birds (_a_, _b_). president hitchcock has distinguished the tracks of more than thirty species in the sandstones of the connecticut valley. birds, reptiles and marsupial animals, seem to have been first introduced during this period. [illustration: fig. .] the new red sandstone is well developed in all its members on the continent of europe. in england, all the members are present, except the muschelkalk. the triassic portion of it occurs in north america. it is found in detached portions, probably as parts of a continuous formation, in nova scotia, the eastern part of maine, the connecticut valley, and from new jersey southward through pennsylvania, maryland, &c., to south carolina. . _the oölitic system._--the lower portion of this system is the lias, and consists of a series of fissile, argillaceous limestone, marl, and clays. the _oölite_ forms the intermediate member of the system, and consists of alternations of clay, arenaceous rock and limestone. some of the limestones have an oölitic structure, and the whole system takes its name from this circumstance, though this structure is not found in all parts of it, and is often found in other formations. the central part of the oölite, the coral rag, is principally a mass of corals and comminuted shells. the _wealden_, the highest member of the oölitic system, is an estuary deposit, consisting of calcareous beds, followed by sandstone, and terminated by the wealden clay. this system is throughout highly calcareous, and furnishes, wherever it is developed, valuable materials for architectural and ornamental purposes. this system is distinguished for the great amount and variety of its organic remains. the _vegetable productions_ were intermediate between those of the coal period and those of the present time. the upper oölite, in the south of england, contains the stumps of trees and other plants, rooted in a black carbonaceous layer, evidently the soil from which they grew. these stumps and prostrate trunks are the remains of coniferous trees of large growth. (fig. .) corals occur in great abundance; also encrinites (fig. ), mollusks (fig. ), and cephalopoda. [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] but this system is specially characterized by the remains of saurian reptiles. the ichthyosaurus (fig. , _a_) was a marine animal, having the general form of a fish, while its head, and especially its teeth, resemble those of the crocodile. it was an air-breathing animal like the cetacea, and was furnished with similar paddles. it was carnivorous, and was undoubtedly the largest and most formidable animal existing in the earlier part of the oölitic period. its length could not have been less than thirty or forty feet. [illustration: fig. .] the _plesiosaurus_ (fig. , _b_) was also a marine animal, and in ninny respects similar to the ichthyosaurus; but its general form was more slender, its head was small, and its neck was of great length, the cervical vertebræ exceeding in number those of the swan. [illustration: fig. .] the _pterodactyle_ (fig. ) was a small saurian, of the size, probably, of our largest eagle. the finger-bones, which in the other saurians form the paddles, are in the pterodactyle very much lengthened, so as to support a membranous expansion, like that of the bat. these wings were of sufficient size to enable it to sustain itself in the air, and to make a rapid and easy flight. the _iguanodon_ is a wealden fossil, remarkable for its great magnitude. it is estimated that its length was seventy feet. it was a lizard, adapted for motion on land, and was herbivorous. this formation is well developed in england, and, with the exception of the wealden, on the continent of europe. it has been supposed that no part of the oölitic series was to be found in this country; but there is a highly arenaceous rock occupying the valley of the james river, in the vicinity of richmond, virginia, of considerable extent, and a thousand feet in thickness, containing a bed of coal of forty feet in thickness, which, from its fossils, must be referred to the oölitic series. . _the cretaceous formation._--the lower part of this formation consists of _greensand_, interstratified with beds of clay. the intermediate portion is a mixture of argillaceous greensand and _impure chalk_. the upper part is composed of _chalk_, which is a friable, nearly pure carbonate of lime. the strata of chalk are separated, at intervals of from three to six feet, by layers of flint, either in the form of nodules or of continuous strata. these characters, by which the cretaceous system is known in england, are but partially recognized elsewhere. thus, in the alps, the "neocomian system," consisting of crystalline limestones, is the equivalent of the english greensand; while the greensand of this country is the equivalent of the white chalk of england. [illustration: fig. .] [illustration: fig. .] the fossils of the cretaceous formation are very different from those of the oölite, and are such as to show that it was deposited in deep seas. _microscopic shells_ are often so abundant as to constitute a large proportion of the mass. _zoöphytes_ are very numerous, such as sponges, corals, star-fishes (fig. , _d e_), and a few crinoidea (_b_). mollusks were also abundant, and cephalopoda, consisting of chamber-shells and belemnites (fig. ). the belemnite probably resembled the existing cuttle-fish; but the remains consist, in most cases, of a partially hollow calcareous substance (_b_), which was contained within the animal, and formed its skeleton. the chalk and greensand are largely developed in england; and the same formation, with different lithological characters, is found in great force flanking the principal mountain ranges of southern europe, and extending into asia. in this country the system commences with the greensand and friable limestones of new jersey, and following the alleghany range to its southern termination, it bends around into a north-western direction, and is continued into missouri. . _the tertiary system._--the tertiary strata embrace the formations from the cretaceous to the human era. they consist of clay, sand, sandstone, marl and limestone, and are distinguished from the lower rocks by being less consolidated; though the limestones are in some instances solidified, and resemble the strata of earlier origin. the tertiary strata are generally of less thickness than the older formations, and less continuous, being local deposits formed in lakes and estuaries. in a few instances they have been thrown into inclined positions, though in most cases they have been but slightly disturbed, and raised but a few hundred feet above the present level of the sea. the late tertiary strata seldom overlap the older, so as to indicate their relative ages by superposition. they have therefore been separated into groups according to the proportions of living and extinct species of shells which they are found to contain. the oldest tertiary or _eocene formation_[a] contains only four per cent, of living species, the _miocene_ contains seventeen per cent., the pleiocene forty per cent., and the _pleistocene_ ninety per cent. [a] _eös_, dawn, and _kainos_, recent. the formation which commenced at _the dawn of the recent period_, containing but a small number of living species. miocene (_meion_, less), less recent than the pleiocene (_pleion_, more). pleistocene (_pleistos_, most), most recent. during the pleistocene period, peculiar conditions existed, by which a great amount of loose material, known by the name of _drift_, was spread over the northern portions of both hemispheres. in america it is found from nova scotia nearly to the rocky mountains, and extending as far south as pennsylvania and the ohio river. in europe, it is found from the atlantic to the ural mountains, and reaching south into germany and poland. it is also found in the colder portions of south america, and in the vicinity of several mountains, as the alps. it consists of irregular accumulations of earthy substances of different degrees of fineness, but characterized by containing masses of rock of considerable size, often of many tons weight, called boulders. rocks having the same lithological characters exist in situ north of where the boulders and other drift are now found, though at a distance often of one or two hundred miles. there can be no doubt but that the drift has been transported from these northern localities; and the polished, striated and grooved condition of the rocky surface, wherever the drift is distributed, has obviously been produced by the passage of the drift materials over it. towards the close of this period, while the land was a few hundred feet below its present level, there were deposited in the valleys of the drift region beds of blue and gray clay, materials which are used in making bricks and coarse pottery; also beds of sand, sometimes evenly spread out, but often thrown into irregular mounds and ridges. in regions which are not covered with drift,--as the south of europe and the united states,--the pleistocene deposits are succeeded, without apparent change of conditions, by those which are now taking place. the formations of the tertiary period are distinguished from those of the cretaceous period by the absence of deep-sea fossils, and from the oölite by the absence of its characteristic saurians. the mollusks are also very different, such genera as the cerethium (fig. ), murex (fig. ), and conus (fig. ), which abound in the present seas, first appearing in the tertiary period. the nummulite (fig. ), a peculiar form of chambered shell, is so abundant as to constitute in some places almost the entire rock. the period is however characterized by the existence of a large number of pachydermatous animals, of which the tapir, hog, horse and elephant, are examples of living species. [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] the _paleotherium_ (fig. ) resembled, in most respects, the tapir. it was furnished with a short proboscis, and the foot was divided into three toes. the length of the largest species was about that of the horse; but its body was larger, and it was of less height. [illustration: fig. .] [illustration: fig. .] the _anoplotherium_ (fig. ) was a more slender animal, and resembled in size and general form the gazelle. the _megatherium_, an animal of the late tertiary epoch, was larger than the existing species of elephant, and in its general structure and habits resembled the sloth. the _mastodon_ (fig. ) lived during the latest portion of the tertiary epoch. its remains are found most abundantly where the animal seems to have perished by sinking into the soft marshy ground near the brackish springs of new york and kentucky. but they are found also in europe and asia. it was larger than any existing land animal, and was nearly allied in structure and habits to the elephant. [illustration: fig. .] the _mammoth_ was a species of elephant, now extinct, of which remains are found with those of the mastodon, but in the greatest abundance in europe and asia. a large number of skeletons, many of them imperfect, have been discovered in the low grounds in the south-east of england. it was this animal which was found encased in ice and sand in siberia, in . contemporaneously with the existence of these huge animals, a near approach was made to the present fauna of the earth, by the introduction of ruminant animals resembling the ox and deer, and especially by the existence of the class of animals which in anatomical characters stands next to man, the apes and monkeys. the tertiary system, though not generally so continuous over extended areas as the older formations, yet constitutes the surface of a very large part of europe. (see fig. .) in the united states the earlier portion is found along the seaboard, from new jersey to louisiana, and extending back towards the mountains to a distance varying from ten to one hundred miles. the later deposits are found in detached portions throughout the eastern and middle states. it covers a large surface in south america, and is found in india. . _the recent formation._--it is intended to embrace in this term strata which have been formed since the creation of man. it is, however, impossible to separate them by any well-defined characters from those of the tertiary period. the recent formation consists of land which is forming by the filling up of lakes, and by the increase of deltas from the accumulated sediment which rivers have furnished. there is, however, no doubt but that formations on a large scale have continued in progress over extensive areas of the bed of the sea; and they have been no less rapid, we may presume, than they were in earlier periods. but, though they are preserving the records of the present era, they will probably remain in a great measure inaccessible for many ages. these deposits, so far as they are accessible, are found to contain the remains of plants and animals (including man) now living in the vicinity where the deposits are forming. section vi.--fossils. any organic substance imbedded in a geological formation, or any product of organic life, as a coprolite or a coin, or any marking which an organic substance has given to a rock, is regarded as a _fossil_. the study of fossils, as a branch of practical geology, requires an acquaintance with the principles and the minute details of botany and zoology. without this knowledge, however, many of the general conclusions to which the study of fossils has led may be understood. . _fossils are preserved in different ways._--when any organic substance is imbedded in a forming rock, it may itself remain; or it may be removed by the infiltration of water, or other causes, so gradually as to leave its form, and even its most delicate markings, in the rock; or some mineral substance may have been substituted, and fill the space which the organic substance once occupied; that is, it may be an organic substance preserved, it may be an impression of it, or it may be a cast of it. . the process by which the substitution in this last case is effected is called _mineralization_. the mineralizing ingredient is generally derived from the contiguous rock. in siliceous rocks it is silex. in calcareous rocks it is carbonate of lime. when iron is diffused through a rock, it often becomes the mineralizer. the substituted mineral is generally a very perfect representation of the original fossil. we cannot therefore suppose that the original substance was entirely removed before any of the mineral matter was deposited. the substitution must have taken place particle by particle, as the organic matter was removed. fossils are, in fact, often found, in which the mineralization has been arrested after it had commenced, so that the fossil is in part an organic and in part a mineral substance. it has been proved, by direct experiment, that these changes of removal and substitution are simultaneous. pieces of wood were placed in a solution of sulphate of iron. after a few days, the wood was found to be partially mineralized, and after the remaining ligneous matter had been removed by exposing it to a red heat, "oxide of iron was found to have taken the form of the wood so exactly, that even the dotted vessels, peculiar to the species employed, were distinctly visible under the microscope." . as the fossiliferous strata are generally of marine origin, it is to be presumed that only a small proportion of terrestrial animals are preserved; and our knowledge of the organic remains which are preserved is yet so imperfect, that discoveries are constantly making, as examinations are extended. still, enough is known to enable us to draw some satisfactory conclusions as to _the order in which living beings were created upon the earth_. though most of the earlier organic forms which have been preserved are of animal origin, yet vegetable remains occasionally occur in connection with them, and we must suppose vegetables to have been produced abundantly. for all animal food consists of vegetable substances, or of animal substances which have once existed in the vegetable form. no animal is capable of effecting those combinations of inorganic matter upon which its growth and sustenance depend. we may therefore conclude that _the introduction of animals and vegetables was contemporaneous_. the greatest development of vegetable life was, however, during the carboniferous period. the design of this abundant growth was prospective. it was not produced for the support of animal life, but for fuel, and stored till man should be introduced, and so far advanced in civilization as to make this supply of carbonaceous matter subservient to his wants and happiness. in the earlier periods, the lower forms of animal life were, beyond all comparison, the most abundant; yet the four great divisions of the animal kingdom, radiated, articulated, molluscous, and vertebrated animals, were all represented. there is, however, no evidence that any vertebrated animals, except fishes, were created till after the carboniferous period. in the next formation, the new red sandstone, we find the tracks of reptiles and birds, and probably of marsupial animals. the first evidence of the existence of mammalia in great numbers is in the tertiary period, when the pachydermata and edentata were so much more abundant than they have ever been since, and when the bimana first appear. but there is no evidence from geology that man existed till after the close of the tertiary period. the grounds upon which contrary statements have sometimes been made are untenable. in ohio a very perfect impression of a human foot was found on a slab of limestone of the silurian age. but it was subsequently ascertained to have been common for the aborigines, in the vicinity of their encampments, to cut in the rocks, with surprising accuracy, the forms of the tracks of man and other animals. there is a human skeleton in the british museum imbedded in solid limestone, and another in paris, both taken from guadaloupe. it was at one time supposed, from the degree of solidification of the limestone, that it must have been formed at an early geological period; but it is found that the beach-sand of that island now solidifies rapidly, from the carbonate of lime which the waters there hold in solution. it is rendered probable that the skeletons found there have not been buried more than a century and a half. . as many parts of the bed of the present seas, which are probably receiving detrital matter constantly, are unfavorable for the development of animal life, while other parts are highly favorable, it might be presumed that animal life would be equally scanty in particular localities while the earlier rocks were forming, and in other localities very abundant. hence some strata, for hundreds of feet in thickness, are composed almost entirely of fossils, while other strata are nearly or quite destitute of them. the same member of a formation may in one place be full of fossils, and in another without them. _the distribution of fossils_ is therefore subject to no general law; at least, none of which we can avail ourselves, in the search for them. . the value of fossils in geology consists in the use which is made of them in determining _the origin and age of strata_. as the animal species which inhabit bodies of fresh water are always different from those found in the sea, their remains constitute the best means of determining whether a formation is of _fresh water_ or _marine origin_. in order to decide this point, it may, in some cases, be necessary to be acquainted with the habits of particular species. in most cases, however, it will be sufficient to remember that in fresh-water formations, first, there are no sponges, corals, or chambered shells; second, the univalves all have entire mouths (fig. ). third, the bivalves are all bimuscular (fig. ). if, therefore, a formation is found to contain sponge, coral, a chambered shell, a univalve with a deeply notched mouth (fig. ), or a unimuscular bivalve (fig. ), it must be considered a marine formation. [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] we have seen that the same formation, as exhibited in different places, differs in its thickness, composition and degree of solidification. if we could trace the strata through all the intermediate space, we might be certain of their being the same formation, notwithstanding the change in lithological characters. but this can seldom be done, even for a few miles in extent. sections of the strata are obtained only occasionally, where rivers have cut through them, or where, over limited areas, the soil has been removed from the outcropping edges. it is also frequently the case that the strata are so much disturbed that their position will furnish no aid in determining their age. when folded axes occur (as here represented), the older strata are often the uppermost. there is an instance in the alps in which strata of vast thickness have been inverted during the process of upheaval, and now rest on a bed of rock formed from the debris which they had supplied. [illustration] and yet it is important to determine what formations are of the same age, notwithstanding their displacements, difference in lithological characters, and separation by great distances and by mountains or oceans. this determination can be made only by a comparison of the imbedded fossils. it is found that every formation, and every important member of a formation, contains an assemblage of fossils peculiar to itself. when very widely separated, the species of fossils may not be identical, but so very similar that they are regarded as equivalent species. _the identification of formations_ consists in the identification of fossils. it is for this purpose mainly that fossils are regarded as of so great importance. . if each formation is characterized by the presence of new species, it follows that _the work of creation was a progressive one_, continued through long periods of time. the latest creation of which we have any geological evidence is that of man. and if the leading design of the existence of this earth was as a theatre for the development of moral character, it is to be presumed that the work of creation ceased when a species possessing moral capacities had been introduced. it follows also, from what has been said, that there has been a constant disappearance, a death, of species. it would seem that each species has a life assigned to it, which is to be completed and surrendered. though its continuance is many times longer than the life of any individual of the species, yet _it is the course of nature that species should disappear_. there may be something in the constitution of each species by which its continuance is limited, making an old age and death necessary, as it is in individuals. but there are other causes by which the duration of species may often be terminated. the subsidence of new holland would cause the destruction of a large number of species. the preservation of the human species was at one time effected only by a special and miraculous interference. slowly operating causes are now at work, by which many species, such as the elephant, wolf and tiger, will at length become extinct. their existence in a natural state cannot long be continued in a civilized country. the forest, their natural abode, disappears, and some are intentionally destroyed, because they render life and property unsafe. under the operation of these causes, the irish elk (cervus giganteus) has become extinct, probably within the human era. the dodo, a gallinaceous bird, found living when maritime communication between europe and the east indies was first established, is now extinct. the apteryx, a bird belonging to new zealand, has probably become extinct since the commencement of the present century. section vii.--the time necessary for the formation of the stratified rocks. there are no means of which the geologist can avail himself to determine the antiquity of the earth, or the amount of time since the sedimentary deposits commenced. but a nigh degree of antiquity may yet be shown. the materials for all the stratified rocks have been obtained by the destruction of previously solidified igneous rocks. this destruction may have been accomplished in part by the operation of volcanic forces, but much of it is the result of slow disintegration, and of the eroding power of running water; and we can scarcely conceive of a period sufficiently protracted for such results. this conclusion of the high antiquity of the earth is confirmed by observing that the stratified rocks consist of layers often not thicker than sheets of paper, and probably not averaging the tenth of an inch; and yet each layer is separate from the rest, in consequence of some change in the conditions under which it was deposited. each layer was probably produced by the deposition of all the sediment furnished at one time, and hence only as many layers would be formed in a year as the number of freshets in the rivers which furnished the materials. if we consider the fossiliferous and metamorphic rocks to be each forty thousand feet in thickness,--which is not too large an estimate,--we must reckon the years by hundreds of thousands to make the time sufficiently extended for the result. all the formations of any considerable extent now above the surface of the sea existed before the creation of man, for none of them contain any evidence of the existence of human beings; and if they had existed while these strata were forming, sufficient evidence would have been left of the fact, either in the form of fossilized human bones, or of works of human art. hence, whatever be the estimate which we form of the antiquity of the earth, from the slowness of denudation, or from the thickness of the strata, we must now add to that estimate the period elapsed since the creation of the human species. we have seen that at different periods of the earth's history different species of animals inhabited it. we are unable to fix with accuracy the ordinary duration of species. but the species which are now extinct probably had an existence as long-continued as will be enjoyed by species now living. many recent species are known to have existed at least nearly six thousand years, without, in most cases, any indications of their soon becoming extinct. whatever period be assigned as the ordinary duration of species, that period has been several times repeated; for the earth has been several times re-peopled, and every time by species which had not before existed. moreover, the _amount_ of organic matter in the strata must have required long periods of time for its accumulation. the vegetable deposits, now converted into coal, are generally several feet thick, and often over a hundred feet, and are known to extend over several thousand square miles, both in this country and in europe. many of the sedimentary rocks consist almost entirely of animal remains. the mountain limestone, for instance, is eight hundred feet or more in thickness, and in some places consists of the exuviæ of encrinites and testacea. in other cases the length of time required is shown, not from the amount of organic remains, but from the evidence that they were deposited very slowly. the polishing stone called tripoli is found in beds of ten or twelve feet in thickness, and is composed entirely of the siliceous shells of animalcules, so minute that, according to the estimate of ehrenberg, the number in a cubic inch is forty-one billions. several other rocks, such as semi-opal and flint, are sometimes found to have a similar constitution. the time necessary for the accumulation of beds several feet thick by the shells of animalcules so minute must have been very great. each of these facts carries us back to a period immeasurably anterior to the creation of man, as the epoch when the sedimentary deposits commenced. there are no facts in geology which point to a different conclusion. it is of the utmost importance to the geological student to familiarize himself with this principle. it will assist him in comprehending the greatness of geological changes, and in applying other principles in explanation of geological phenomena. this principle, so obvious to any one who allows himself to reason from the facts which geology presents, has sometimes been regarded as at variance with the mosaic account of the creation. and if this account really assigns an antiquity to the earth of not more than six thousand years, the difficulty exists. the statements made by moses are found, upon examination, to be of the most general character. they assert, in the first place, simply that "in the beginning god created the heaven and the earth." the time which elapsed after this first act, and previously to the acts of creation subsequently recorded, is not limited by the sacred narrative. it may have been during this indefinite lapse of time that god gave existence and enjoyment to a large number of animal species on the surface of the earth, and at the same time effected most of those physical changes in the crust of it which have rendered it a fit abode for intellectual and moral beings. but if the word _day_, in the first chapter of genesis, be considered to mean a prolonged period (and philologists regard such an interpretation as admissible), then that chapter is a record of the most important events in the history of the earth up to and including the introduction of man. and the account, thus understood, coincides with the results of geological examinations. instead, then, of discrepancy between the works and the word of god, we have this remarkable fact, that a history of the earth, written long before the science of geology was known, is not contradicted, but confirmed, by the progress of science thus far. chapter iii. of the changes to which the crust of the earth has been subjected. section i.--changes which have taken place at great depths below the surface. the lowest change of winch we can gain any information is the _formation of granite_. it will be shown hereafter that it has been in a melted state, and that it has taken its present form on cooling. but whether any considerable portions of the granitic masses, or of the melted masses now below the surface, have resulted from the fusion of stratified rocks, we have not the means of determining. it is, however, not improbable, that in the changes of level to which the crust of the earth has been subjected, the stratified rocks may have gone down so far as to become melted. at the same time, the melted rock which is thrown to the surface by volcanoes is subjected to the various destroying agencies by which it becomes sedimentary matter, to be deposited as mechanical strata. thus, as the igneous rocks from below are brought up to furnish materials for mechanical strata, there must be an equal amount of depression of the mechanical strata towards the seats of igneous action. and if this change takes place more rapidly than the thickness of crust increases, then portions of the sedimentary rocks must be undergoing fusion. next above the granite an immense thickness of rock occurs, which exhibits, from its stratification and from the water-worn fragments which it contains, distinct evidence of its mechanical origin. and yet it is very different from the later mechanical formations. it is more highly crystalline; it has, to a great extent, assumed a cleavage distinct from the planes of stratification, and chemical affinity has been so far active as to produce new combinations, and give to them their peculiar crystalline form, as in the case of garnets, iron pyrites, &c. these strata also differ from those above them in containing no organic remains. it is not certain that organic life existed on the earth at the time when these rocks were deposited. either it did not, or the evidence of it in the strata of that period has been obliterated. the changes have at least been sufficient to justify their being characterized as _metamorphic rocks_. section ii.--changes in the mass of the stratified rocks. . the stratified rocks were deposited as mud or sand, and were at first in a yielding state. most of these deposits have become _solidified rock_, such as limestone, clay slate and sandstone. the chalk of england is, however, but imperfectly consolidated, the great sandstone formation of new holland is a friable mass easily disintegrated, and occasionally beds of clay in a plastic state are found as far down as the coal. among the later rocks the solidification is less general, though there is some degree of hardening in all except the most superficial layers. the _fissile structure_ results from the solidification of the particles composing each layer separately. . since the solidification of the strata, or perhaps in connection with it, there has been something of movement among the particles, resulting in mineral veins, conchoidal structure, &c. one of the most general changes of this kind is that by which a mass becomes separable into thin sheets, independent of the stratification, and not parallel with it. this structure is represented by fig. , in which the heavier lines are those of stratification, and the lighter of _cleavage_. . the strata have been everywhere more or less broken, and the _fractures_, nearly vertical, extend to groat depths. when a fracture reaches the surface, it often becomes a channel for water. it is thus widened by the erosion, the deepest parts become filled with debris, and it becomes a _gorge_, _ravine_ or _valley_. [illustration: fig. .] if the fracture does not come to the surface, it becomes a _cavern_. in limestone, caverns which are formed in this way are very frequent, and extend for many miles. there is generally a stream of water running through them, but not of sufficient volume to have produced the erosion which has been effected. when the sides of the fracture are but little separated, some mineral often separates itself from the adjacent rock, and filling up the space, reunites the broken parts. it is then called a _vein of segregation_ (fig. , _a b_). but the fracture is more frequently filled with some volcanic rock injected from below. it is then a _dike_ (_c_ _d_), and may have a width of many rods, though it often diminishes in width till it is a mere thread. a dike of which the injected material is a metallic ore is a _mineral vein_. [illustration: fig. .] . the uplifting force by which the fracture is produced has frequently raised the rock on one side higher than it has on the other. this is called a _fault_. (fig. .) the unequal movements by which the fault is produced seem in some instances to have been repeated several times, and the grinding of the broken edges upon each other has polished and striated the sides of the fracture. [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] . sedimentary rocks are often found with the planes of their strata more or less _inclined_. it is evident that they were not thus formed. the depositions of sediment from water will always be horizontal, or, at most, only slightly inclined. but there is often evidence in the rock itself that its strata were once horizontal. it is frequently observed that vertical strata contain pebbles with their longer axes in the plane of the strata. (fig. .) when these pebbles were deposited, the longer axes would take, on an obvious mechanical principle, a horizontal position. their present vertical position must have resulted from a change in the position of the strata in which they are enclosed. the same thing is shown by the position of a petrified forest in the south of england, known as the portland dirt-bed. some parts of it are inclined at an angle of forty-five degrees. the position of the vegetable remains (fig. ) shows that when they were growing the surface was horizontal. the line _b d_ (fig. ), on inclined strata which makes with the horizon the greatest angle, is called the _direction of the dip_. the angle thus formed (_a b d_) is the _angle of inclination_. when inclined strata come to the surface, the exposed edge, _b c_, is the _outcrop_, and the line of outcrop on a horizontal surface is called the _strike_ of the strata. [illustration: fig. .] when the inclined position is produced by an uplift of the strata, along a given line, so that they dip in opposite directions, this line is called an _anticlinal axis_, as at fig. . if, however, the strata are fractured along this line, as at _b_, the fracture becomes a _valley of elevation_. [illustration: fig. .] if depression take place along a given line, as at _c_, the strata will dip towards this line, and it will be a _synclinal axis_. the depression will be a _valley of subsidence_. a synclinal axis would also be produced by an elevation of the strata, as at _d_ and _e_, on each side of it, and the valley thus produced is one of elevation. when successive sets of strata, as _f_ and _d_, fig. , are not parallel, they are said to be _unconformable_. [illustration: fig. .] [illustration: fig. .] . when the strata are subjected to displacement, they do not always take a merely inclined position, but are often _contorted_ (fig. ), or folded together (fig. ). these _folded axes_ frequently succeed each other for many miles. (see figs. and .) in the case represented by fig. , if the highest portion has been removed, so that the line _a b_ represents the actual surface, we shall have apparently a succession of deposits, of which those at _b_ would be the newest, and the oldest would be found at _a_, when in fact the strata at the extremities are parts of the same layer. it is probable that disturbances like those now mentioned have been taking place continually, in different places, from the earliest times. there have been no periods of universal disturbance, and none of universal repose. on the contrary, the periods of disturbance in one part of the world have been periods of repose in another. for example, the coal measures of europe were much broken and disturbed before the deposition of the new red sandstone, and the close of the coal period was at one time supposed to have been a period of general convulsion. it is now ascertained that the principal coal-fields in this country were not much disturbed at that period, and have not been since. section iii.--changes of elevation and subsidence. the continents, if we except the more rugged and broken portions, rise from the sea with an almost imperceptible ascent; and even the mountains have a much gentler slope than we are apt to suppose, so that a section of the earth parallel to the equator would be almost a perfect circle. the slope of a mountain, from its base to its highest point, rarely forms with the horizon an angle of as much as twelve degrees. in the following figure ( ), a represents the peak of chimborazo, b of teneriffe, c of Ætna, and d of mount loa, the principal volcano of the sandwich islands. the highest mountains would be represented on a twelve-inch globe by an altitude of less than the one-hundredth of an inch above the level of the sea. but the rising and sinking of these masses, though so small compared with the dimensions of the earth, are yet geological changes on the largest scale. . _the elevation of mountains._--mountains have formerly been covered with the waters of the ocean. this is evident, in the case of some mountains, from the existence of stratified rocks reaching to the summits. the stratification could have been produced only by deposition from water. it is, moreover, evident from the existence of marine fossils, distributed through these strata, so abundantly, that they cannot be accounted for on any other hypothesis than that the animals lived and died where the remains of them are now found. these strata must therefore have formed the bed of the sea while the fossils were accumulating. [illustration: fig. .] there is no _direct_ evidence that the granitic mountain peaks were ever submerged. but there is reason for believing that the sedimentary strata which now occupy the lower slopes were, at the time of their deposition, continuous,--the igneous rock having subsequently broken through them,--so that the waters of the ocean once rested on the whole area which the mountain now occupies! if the ocean could ever have been above its present level sufficiently to have covered all the sedimentary rocks, we might assume that the height of mountains has not been changed. but the level of the ocean cannot be subject to much variation. the total amount of water on the globe is always the same. if the continents and mountains were all submerged at once, and the waters were expanded by the highest temperature consistent with the liquid form, there would not be a change of level of more than two hundred and fifty feet. we may assume, then, that the ocean level has always been essentially the same that it now is. we must therefore conclude that the sedimentary rocks, and the mountains of which they form a part, have been elevated to their present position from the bed of the sea. different mountain ranges have been elevated at different periods. the silurian and carboniferous formations were deposited before the alleghany mountains, which they contributed to form, were elevated; while the new red sandstone and the cretaceous and tertiary formations were deposited subsequently to the upheaval. they are accordingly found at the base of the range, nearly horizontal, and have risen above the level of the ocean only as the continent generally has risen. the pyrenees were elevated after the deposition of the cretaceous rocks, and have carried them up so that they appear at a high angle, while the tertiary rocks at the base are horizontal, as in the united states. the andes have carried up the tertiary rocks with them, and their elevation must therefore belong to a recent period. it appears that they are even yet rising. it has recently been shown that the alps have been subjected to upheaval at several distinct periods. at the close of the silurian period they formed a cluster of islands. at the commencement of the tertiary period they became a mountain range, and at the close of that period they were thrown up some two thousand feet higher, to their present position. nearly the same things will probably be found true of other mountain ranges, when their structure has been minutely studied. the elevation of contiguous parallel ridges will necessarily leave intervening _valleys of elevation_. as mountain ranges generally consist of several such ridges, valleys of this description are numerous, and they are often of great extent. it is obvious that there are mountains in the sea of as great height above the lowest valleys as the mountains of continents are above the level of the sea. if a new continent should hereafter be formed by the elevation of a large area of the bed of the sea, the existing mountains, now appearing in the form of islands, would partake of the general movement, and the new continent would have the same general diversities of surface as existing continents. the mountains would have existed long before the continent. it is therefore to be supposed that the mountains of the present continents were elevated before the continents, and that they stood for long periods as islands, exposed to the action of waves, tides, and marine currents. . _the elevation of continents._--continents have been elevated by so slow a movement that it has not generally been perceived, even when they have been peopled by nations advanced in civilization. and yet satisfactory evidence is always left of former sea-levels. almost every seaboard furnishes examples of beaches, evidently once washed by the sea, but now elevated more or less above high water. at lubec, near the northern extremity of the coast of maine, barnacles[b] are found attached to the rocks eighteen feet above high water. the pilots at that place, and for a hundred miles north and south of it, speak of the ship-channels as diminishing in depth, though it is certain that they are not filling up. such facts are to be explained only by supposing that the coast is rising. [b] the barnacle is a marine animal, permanently fixed to the rocks, and live but a short time without being surrounded by sea-water. lakes are numerous throughout the northern portions of north america, which are receiving annually large quantities of sediment, and must ultimately become alluvial plains. those of moderate depth, as lake erie, cannot require periods very protracted to fill them. their continuance in such abundance indicates that the elevation of the continent to its present height is comparatively recent. this conclusion is confirmed by evidence of another kind. throughout this region of lakes, beds of clay containing the remains of existing species of marine animals, are found at all elevations from the sea-coast, to the height of about four hundred feet, but not higher. these clay beds are very recent, and were deposited when the surface was four hundred or five hundred feet lower than it now is; and this amount of elevation has left the existing lakes scattered over the surface.[c] [c] "it is remarkable that on the shores of the great lakes there are certain plants the proper station of which is the immediate neighborhood of the ocean, as if they had constituted part of the early flora of those regions when the lakes were filled with salt water, and have survived the change that has taken place in the physical conditions of their soil."--_torrey's flora of the state of new york._ [illustration: fig. .] the following (fig. ) exhibits europe as it was during the silurian epoch, and fig. as it was at the commencement of the tertiary epoch. the land, as it then existed, is represented by the white surface, the present waters by the dark shading, and the land which has been reclaimed from the ocean by elevation since those periods by the lighter shading. [illustration: fig. .] the whole southern part of south america, embracing an area equal to that of europe, has been elevated within a very recent period; and some parts of it, if not all of it, are still rising. the shells found on the plains from brazil to terra del fuego, and on the pacific coast, at a height of from one hundred to thirteen hundred feet, are identical with those now inhabiting the adjacent seas. and "besides the organic remains, there are, in very many parts, marks of erosion, caves, ancient beaches, sand-dunes, and successive terraces of gravel," all which must have resulted from the action of the waves at a period not remote. at lima, articles of human skill peculiar to the original inhabitants of peru were found imbedded in a mass of sea-shells eighty-three feet above the present sea level. the elevation on the pacific coast has been in part by sudden uplifts of a few feet at a time; but it is found, from time to time, that there has been a change of level, amounting to a foot or more in a year, when there have been none of these sudden movements. a considerable portion of europe, reaching from north cape in norway to near the southern part of sweden, more than a thousand miles, and from the atlantic to st. petersburg, more than six hundred miles, has been rising at the rate of about three feet in a century, for at least two centuries, and probably much longer. this change is proved by the occurrence, at considerable elevations above the sea, of shells now found in the baltic; by rocks once sunken, now raised above the surface of the sea, and by ancient seaports having become inland towns. to determine the truth by actual measurement, the royal academy of stockholm, about thirty-five years since, caused marks to be cut in the rocks along the coast, to indicate the ordinary level of the water. this is easily ascertained, as the baltic is nearly a tideless sea. the present level of the sea, compared with that indicated by the marks before mentioned, leaves no doubt that the country is rising. . _the subsidence of land._--elevations can be shown to have taken place by fossils, and by other evidences of former sea levels which are left on the surface; but depressions leave but few indications of change of level. it is yet doubtful whether the depression is equal to the elevation; that is, whether the amount of land remains nearly constant, or whether there has been an augmentation of the dry land within the tertiary and recent periods. we are certain that the augmentation, if any, has not been equal to the elevation, for subsidences to a great amount are known to have taken place. there are occasional instances of submerged forests seen at low tide, at some distance from the shore. there are several near the coast of england and scotland, and near the coast of massachusetts. they are but a few feet below low water, and do not indicate a subsidence of more than about twenty feet. numerous instances are on record of the sinking down of wharfs and buildings near the sea during earthquakes. almost every violent earthquake is accompanied by a change of level. the changes of this kind which have been noticed are in seaport towns, because greater facilities are there afforded for detecting them, and because loss of property awakens attention to them; but there is every reason to suppose that these changes of level extend to great distances both into the country and into the sea. [illustration: fig. .] an immense area in the indian and pacific oceans, probably ten millions of square miles, is undergoing change of level. the lines a b and d g (fig. ) represent nearly the axes of depression; while an intermediate and two exterior parallel lines would represent axes of elevation. the evidence of these changes is found principally in the peculiarities of the wall of coral rock encircling the islands. the following figures represent, in sections, modifications of form of the same island. the coral wall built up around the island by the polyps, from the depth of fifty, or at most of a hundred feet, is shown at _c c_ (fig. ). if the island is elevated, this wall becomes a _fringing reef_ (fig. ), _b'_ becoming the level of the sea, and the animal begins a new wall at the same depth as before. but if the island is gradually sinking, the wall is kept built up to the surface, and becomes a _barrier reef_ (fig. ). a channel is thus left between the island and the reef, which, though gradually filling up with broken coral or other sediment, is generally deep enough for a ship-channel. if the island continue to subside till it disappears, and the coral wall is still kept at the surface, it then becomes an _atoll_, a circular coral island (fig. ), often of many leagues in diameter, beaten by the surf on the outer edge, but enclosing a quiet lake, which communicates only by occasional channels with the ocean. [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] the islands contiguous to the lines a b and c d (fig. ) are uniformly atolls, or are surrounded by barrier reefs, and are therefore subsiding; while the islands at a distance from these lines are surrounded by fringing reefs, which indicate that they are rising. a well-authenticated instance of gradual subsidence is that of greenland. the entire western coast, from its southern extremity to disco island, a distance of six hundred miles, has for the last two centuries been slowly subsiding. the dwelling-houses and places of worship built by the early european settlers are now in part or entirely submerged. the natives are said to be aware of the subsidence, and never build their huts near the sea. . we have thus seen that both elevation and depression may take place. there is reason to believe that these changes of level have, in some cases, been several times repeated. in one of the eastern ranges of the andes, opposite to chili, there is a mass of marine strata of five thousand feet in thickness. about the middle of the series there occurs a silicified forest. in one place a clump of coniferous trees was found of more than fifty in number, and a foot or more in diameter. the base of the strata must have been twenty-five hundred feet below the surface of the sea, in order to admit of the deposition of the first half of it. it was then elevated, so that a forest grew upon its surface. it was then depressed at least twenty-five hundred feet, more, to admit of the deposition of the subsequent strata, and the whole is now uplifted to form a mountain range of eight thousand feet in height. [illustration: fig. .] the temple of jupiter serapis, near naples, in italy, was built near the sea, about eighteen hundred years ago. it was gradually submerged, and finally lost by the deposition of sediment nearly to the top of the columns. it was afterwards elevated, so as to be entirely above the level of the sea. the remains of the temple (fig. ) were afterwards discovered by the columns projecting a little above the ground. the sediment was removed to the depth of forty-six feet, when the workmen came to the base of the columns, and to a pavement seventy feet in diameter. in an artist was employed to take drawings of the ruin. the pavement was then above the level of the sea. sixteen years afterwards the same artist found the pavement covered with water, and the depth has continued to increase since that time. it is considered that for the last forty years the depression has been three-fourths of an inch a year. instances enough have now been given to show how extensively the system admits of change. they are sufficient to justify us in searching for indications of great revolutions in past times, even where no such indications have as yet been discovered. they will serve as a key to many otherwise inexplicable phenomena, in order to the interpretation of such phenomena readily, we must cease to look upon these as exceptional cases, and regard them not only as facts, but as facts of frequent occurrence. from the examples which have now been given, as well as from speculations upon the cause of these changes, it seems highly probable that all the surface of the solid portion of the earth, whether land or the bed of the sea, is undergoing changes of level. it may be so gradual that in the life of an individual it would be imperceptible, even where the best means of detecting it exist. these means are generally the works of man, and they are themselves so liable to change, that it would be scarcely possible to detect variations of level, which amount to but a few inches in a century. if we admit that the relations of land and water have always been variable, it is impossible to arrive at any certain conclusion as to the amount, position or form, of the dry land at any former period. we may determine, with some degree of certainty, what portions of the present continents were submerged at particular epochs. thus, we may infer that most of this country was submerged during the silurian period, from the great extent of the silurian rocks; and, from the limited extent of the chalk formation in this country, we know that during the cretaceous period most of the continent was above the surface of the sea. but we have absolutely no data for determining what portions of the bed of the sea were at any time dry land. it is supposable that the land has been principally confined to the equatorial regions at one period, and to the polar at another. at still a different period the land may have existed as islands scattered through a general ocean. these relations may, therefore, be assumed to have existed, if there are geological phenomena which best accord with such relations. section iv.--changes on the surface of the earth. . the principal changes of this class consist in the wearing down and removing immense quantities of the surface rock. the form in which the _igneous rocks_, of which the entire crust of the earth was originally composed, now appear, furnishes no assistance in judging of the amount of denudation which they have suffered. we can judge only from the amount of rock for which they have furnished the materials, and these are the whole sedimentary series which exist both as dry land and as the bed of the sea. . the _sedimentary rocks_ have also been subject to great denudation; and we often have, in what is left, some indications of how much has been removed. one of these indications consists in the now level surface of those portions of country in which large _faults_ exist. by the excavations for coal, in england, faults have been discovered of five or six hundred feet. at the time that they were formed, the surface must have presented precipitous escarpments (as represented by the dotted lines in fig. ) of a height equal to the dislocation; but the whole is now reduced to a general level (_z z_), denuding causes having removed the elevated portions. the extent of _valleys_ will often give some idea of the amount of denudation to which a region has been subjected. in the north-west of scotland there is a succession of hills of about three thousand feet in elevation, consisting, for the upper two thousand feet, of horizontal strata of old red sandstone. (fig. .) we cannot conceive that these mountain masses were deposited in their present isolated form. the whole intervening spaces must have been filled with strata continuous with those by which the elevations are formed.[d] [d] "i entertain little doubt that when this loftier portion of scotland, including the entire highlands, first presented its broad back over the waves, the upper surface consisted exclusively, from one extremity to the other, of a continuous tract of old red sandstone; though, ere the land finally emerged, the ocean currents of ages had swept it away, all except in the lower and last raised borders, and in detached localities where it still remains, as in the pyramidal hills of western rosshire, to show the amazing depth to which it had once overlaid the inferior rocks."--_miller, old red sandstone_, _p. _. [illustration: fig. .] [illustration: fig. .] a somewhat similar instance occurs in the connecticut river sandstone, in the central part of massachusetts. the following figure (fig. ) represents two mountains of the sandstone, between which the connecticut river flows. the dotted lines indicate a depth of one thousand feet of the rock which has been swept away. it is also thought that a bed of equal depth has been removed from this section southward, through the state of connecticut, to the sea-coast. . _valleys_, and even many of the larger valleys, are produced by the wearing down of the surface. the lower portion of the connecticut valley is one of denudation, though in its upper part it is a valley of elevation, resulting from the upheaval of the green and white mountains. the water-courses from the mountains are transverse to the direction of the ranges, and generally consist of valleys of denudation. these valleys were no doubt originally fractures, produced while the mountains were rising. the fractures have been subsequently widened by denudation into valleys. [illustration: fig. .] . the rocky surface, beyond the fortieth parallels of latitude, and in the vicinity of glacier-producing mountains, is generally covered with _grooves_ and _striæ_ (fig. ), varying from several inches in depth to the finest perceptible lines. rocks that are of a soft consistence, or which have been long exposed to atmospheric agents, seldom exhibit these marks, though there are probably few places, outside of the parallels before mentioned, where the rocky surface, if it has been protected from atmospheric decay, does not contain such grooving. . another change at the surface consists in the formation of a _soil_; that is, of a superficial layer, of no great thickness, of earthy matter, a large proportion of which is always in a minutely divided state. in some instances it is common sediment, unsolidified; in others, it consists of the surface rock in a state of disintegration; but a large part of the soil within the region where the grooved surfaces are found consists of materials transported from a distance. soils are distinguished according to their predominant minerals, as siliceous, aluminous and calcareous. if siliceous matter is in excess, it will be a light, warm soil, and allow the water to pass through it too freely. if the clay predominates, the soil is cold, stiff, and too retentive of moisture. a proper admixture of these three ingredients constitutes the best soils. there are some other mineral ingredients essential to the productiveness of soils, but they are always in small proportion. in addition to the inorganic part which is common to the upper soil, and the subsoil, there is required, in order to render the upper layer productive, a large admixture of decaying animal and vegetable matter. section v.--changes of climate. our means of determining the climate of any former period consists in a comparison of the fossils of such period with the existing forms of life in warm and cold climates. the earliest abundant _vegetation_ consisted principally of ferns, rushes and mosses, and a larger growth was attained than is attained by any of the allied forms of the present time. we may infer that the circumstances under which these lower forms of vegetable life are now produced in the largest proportion, compared with other forms, and under which they grow to the largest size, are the circumstances approaching most nearly those under which the early vegetation was produced. these circumstances are found to be a position elevated but little above the level of the sea, a humid atmosphere, and the highest terrestrial temperature. such facts favor the conclusion that during the coal period an ultra-tropical climate prevailed, and that the land existed in the form of low islands, thickly set in a general ocean. the peculiar characters of some of the _animal fossils_, from the earliest fossiliferous to the tertiary series, indicate that a warmer climate prevailed during their formation than now exists. the remains of marine animals, such as the cephalopoda, are found in great numbers and in high latitudes, in a fossil state; but similar species, as the nautilus, now abound only between the tropics. the same is true of the crinoidea. coralline limestone is also found in great abundance and in high northern latitudes; but the stone-producing coral now exists only in very warm seas. the remains of saurian reptiles are numerous in the oölite and wealden; but all the larger recent species of the lizard tribe, such as the crocodile, are confined to the warmer regions of the earth. a former warm climate in siberia is indicated by the occurrence there of the remains of elephants. these animals were so abundant that their tusks are now collected as an article of commerce. the abundance and high state of preservation of these remains seem to preclude the explanation that they were conveyed there, from the present tropical regions, by any great geological convulsion. the species must therefore have inhabited the country, though the elephant is now found only between the tropics. the siberian elephant was a different species from any now existing, and, unlike the recent species, had a covering of coarse hair. there is, however, no reason to conclude that it could endure a continued low temperature; and its sustenance would have been impossible, from the very stinted vegetation which that region now affords. we must therefore suppose that siberia enjoyed, at the period when it supported these animals in such abundance, a tropical climate. most of the facts which go to prove a change of climate have been observed in the northern hemisphere; but the explorations in south america and new holland furnish ground for believing that the geological phenomena of the two hemispheres are essentially alike, and that the indications of climate are the same for the same periods. such is, in general, the evidence in reference to climate; and it leads to the conclusion that a highly tropical climate prevailed in the temperate, and for some distance, at least, into the polar zones, in the early geological periods; while there is no reason for supposing that the tropical regions experienced a temperature too high for physical life to endure it. the climate of the earth was characterized then by a higher temperature than now, and by greater uniformity. this was the climate, with perhaps a gradual reduction of temperature, till the later portions of the tertiary period. before the close of the tertiary period, a change occurred, and probably a rapid one, to a more rigorous climate than now exists. the destruction of the elephant in siberia was evidently sudden, and was followed by extreme cold; for the animals are in some cases entirely preserved in ice, and in so perfect a state that, when the ice which surrounds them becomes melted, the flesh is devoured by carnivorous animals. there are occasionally found, in the drift of the boulder period, shells similar to those of the arctic regions, and in a condition to show that they have not been transported. the clay beds of the northern portion of the united states and of canada were deposited during the last depression of that portion of the continent, and they contain the remains of marine animals identical in several instances with species now living, but confined to more northern regions. it must therefore be admitted that the interval between the middle tertiary and the modern era was one of great cold. it is generally referred to as the _glacial period_. very considerable local changes of climate have also occurred within the historical period. thus the mean temperature of the alps has been so reduced that the ancient passes have in modern times become choked up with snow, and other passes have been sought,--a result, perhaps, of additional upheaval. it would seem that siberia is now receiving a milder climate. the ice in which elephants have for centuries been imbedded has been slowly melting for at least thirty years. section vi.--advantages resulting from geological changes. . the division of the general surface into land and water, as well as the diversified form of the land, the existence of mountains and low lands, and the consequent modifications of climate, the waterfalls, and the river-systems, constituting the drainage of continents, are all results of the process of upheaval. . a large part of the mineral substances employed for architectural and economical purposes are oceanic deposits, such as the marbles, slates, sandstones and mineral salt, and would have been inaccessible if they had not been elevated from the position in which they were formed. and the elevation of them above the bed of the sea would have exposed only the superficial layer, if they had not been either irregularly uplifted, as at _e c_ (fig. ), or unequally worn down, as at _b_. [illustration: fig. .] the granitic rocks, as they were formed below the aqueous rocks, must have remained unknown and useless, if they had not been brought to the surface, as at _c_, by the most convulsive efforts of nature of which we have any knowledge. thus, natural mechanical forces have effected for man what the mechanical forces under his control would be entirely insufficient to accomplish. . it is by changes of this kind that we become acquainted with the geological structure of the crust of the earth. mining operations have never extended to a greater depth than three thousand feet, while the inclined position of the strata exposes for examination, along their outcropping edges, _e a c_, the whole series, even to the primary rocks. the upheaval of the granitic rocks, and the removal by denudation of the overlying deposits, shows us the crystalline character which the earthy materials take, when subjected to pressure and cooled from fusion with extreme slowness. thus we have, exposed to observation, the process of nature in the formation and modification of rocks for several miles in depth. of the central portions, however, including by far the largest part of the mass of the earth, we have no knowledge whatever. . _springs_, and the other means of obtaining water for domestic purposes, depend in part upon the inclined position of strata, and the broken and uneven condition of the surface, and in part upon the alternation of permeable and impermeable strata. if all the strata were porous, like the sandstones, the water which falls upon the surface would gradually settle through them to the level of the sea; or, if they were all impermeable, like the clays, the water would pass over the surface, and be collected in lakes or the ocean. as it is, the porous structure of the soil and of some rocks acts as a reservoir, from which the water is gradually discharged, and the intervention of impermeable strata prevents its taking a perpendicular direction downwards. thus, if the stratum _e b_ (fig. ) consists of porous rock, and the one below is impermeable, the water which is absorbed at _e_ will appear at _b_ as a spring. or, if the line _a d_ is a fracture, the water received at c may reappear as a spring at _a_. if the strata were perforated by boring at _e_ till the porous stratum _a_ is reached, the water will rise to the surface, constituting an _artesian well_. an ordinary well consists of an excavation continued till a stratum is reached which is permanently saturated with water. . most of the _metallic ores_ which occur in the stratified rocks, with the exception of iron, are found in fractures or as dikes. without these disturbances of the strata, the ores would have remained either sparingly diffused throughout the adjacent strata, or as a part of the melted mass at the volcanic centres. the ores and metals which are found in the primary rocks are accessible only by the bringing up of these rocks to the surface. the fracturing, displacement, and elevation of the strata, attended, as is often the case, with the destruction of property and of the life both of man and the inferior animals, might, at first view, be thought an unnecessary, if not a wanton infringement upon arrangements already established. but the results which we have noticed, though by no means a full enumeration of the advantages resulting from geological changes, are sufficient to show that even the more violent disturbances to which the crust of the earth has been subjected constitute an important part of that series of adjustments which has rendered it a suitable abode for human beings. these changes are therefore neither useless nor accidental, but are essential parts of a wise and beneficent system. chapter iv. of the causes of geological phenomena. an exhibition of the _composition and structure of the earth_, together with an account, as far as there is reliable evidence, of the modifications which they have undergone, has been the object of the preceding chapters. they are mainly a collection and classification of observed facts. no reference has been made to causes or modes of operation, except in a few cases where it was necessary in order that a statement or description, might be intelligible. if the facts have been given with sufficient clearness and detail to convey a correct general idea of the crust of the earth, we are prepared to inquire what are the agencies employed, and how they have operated in producing it. it is the province of the geologist to question every known power in nature, and to ascertain what geological effects each one is now producing; and, observing what effects are produced by given causes, he is to judge of the causes which have produced like effects in past geological periods. some of these causes are in their nature limited, and effects can be referred to them only within those limits. thus, the congelation of water expands it by a certain proportion of its volume, and beyond that it can have no effect. but the expansive power of steam varies with the temperature; and hence the effects referred to it may be equally varied. thus, we are not to expect exact uniformity of results in all past times, but _the results will vary only as the circumstances vary_ upon which the operation of these causes depends. geological causes, in most instances, operate with extreme slowness; and therefore it will require a series of observations, continued for a long time, to ascertain what are the capabilities of these causes. but a single instance of their effects proves their capabilities thus far. hence, one instance of the deposition of a stratum of salt in a salt lake; of the filling of a fracture with fluid lava; of a volcanic eruption, like that of iceland in ; of the subsidence of a volcanic mountain, as that of papandayang in java; or of the rising of a large area of land, as in sweden, as fully proves that natural causes exist capable of producing these effects, as if the effects were produced daily. as these effects increase in number, and careful observations are made and authentic accounts preserved, the means of correctly explaining geological phenomena will increase. the causes thus far known are atmospheric causes, chemical action, organic agency, and aqueous, aqueo-glacial and igneous action. section i.--atmospheric causes. the oxygen of the atmosphere is capable of uniting with some of the constituents of rocks, by which their cohesion is weakened or destroyed. this is the cause of the rapid disintegration of some varieties of granite. the protoxide of iron which they contain is converted, by contact with the atmosphere, into the peroxide. its volume is thus increased, and portions of the rock are separated from the mass. when granite or limestone contains sulphuret of iron, the oxygen of the atmosphere, in connection with moisture, combines with the sulphur, forming sulphuric acid, by which limestone and the felspar of granite are rapidly decomposed. hence, a rock which contains an oxide or sulphuret of iron should not be used for architectural purposes. carbonic acid is another constituent of the atmosphere which operates as a decomposing agent. the water that falls from the atmosphere is charged with it, and thus becomes capable of dissolving calcareous rocks. carbonic acid is thus indirectly the means of the rapid destruction of rocks of this class. it is also believed that carbonic acid enters into direct combination with some of the constituents of rocks, and particularly felspar; for it is found that in those countries where carbonic acid issues in great quantities from the earth, the rocks, especially those which contain felspar, disintegrate rapidly. masses of many tons' weight, which appear to be solid granite, after being broken are found to be in such a state of decay that fragments may be reduced to sand between the fingers. the moisture of the atmosphere has some effect as a decomposing agent. rocks which are exposed to frequent alternations of moisture and dryness soon crumble into fragments. rain, falling upon the surface of rock, produces, mechanically, a destroying effect, which is not to be overlooked. variations of temperature, especially those alternations above and below the freezing point, have greater influence than any other cause in the destruction of rocks. when the water with which a rock is saturated congeals, the resulting expansion tends to enlarge the interstices, and thus to separate the particles of the rock. when the ice melts, the particles fail to resume the closeness of arrangement with which they were before packed. by frequent repetition of this action, the superficial portion loses its cohesion, and disintegrates. it is also found that in the region of perpetual snow the surface of the mountain masses is covered with rock in a disintegrated or fragmentary state, in greater abundance than below the snow line; but no explanation of this fact has yet been found. in mountainous regions, electrical discharges and violent storms have some destroying effect. winds have considerable power in changing the place of earthy matter in a disintegrated state. in deserts, the sands are carried in great quantities to great distances. the causes now enumerated, when considered separately, and as acting for only limited periods of time, seem hardly worthy of notice; but when considered as operating conjointly, and for indefinite periods of time, they must have produced important changes on the surface of the earth. from these causes, the surface and ornaments of castles and other ancient edifices, and of boulders, and all insulated rocks, are found to be decayed, and often to a considerable depth. it is from these causes that a soil is produced on every surface of rock which is not so exposed to the action of currents that the debris is removed as fast as it is formed. hence it is, also, that a slope of detritus is formed at the base of every declivity, so that the ledge appears only at the highest points. it is from a combination of these atmospheric causes that a large part of the sediment is furnished which brooks and rivers carry away. and when cohesion is not entirely overcome, it is so far weakened that other causes are much more effectual than they would otherwise be, in effecting the disintegration of rocks. section ii.--chemical action. all those changes in which the action is molecular,--that is, between the molecules as such, and not between the masses,--including the effects of the imponderable substances, we regard as resulting from chemical agency. under the control of these molecular forces the crystalline rocks have taken their form; and if the crust of the earth could have remained in a fixed condition, in which these forces would have been in equilibrium, no further chemical action could have taken place. but, instead of being in a fixed condition, the present system is one of perpetual change. various disturbances of this equilibrium of forces,--such, for instance, as the diurnal and annual changes of temperature at the surface, and the still greater secular changes of temperature at great depths,--will bring the chemical forces into operation. the mechanical disintegration of the crystalline rocks, and the deposition of them in strata independently of the chemical affinity of their particles, will give occasion for chemical changes,--that is, for a rearrangement of the particles in accordance with their affinities,--whenever any movement of the particles among themselves can take place. these movements take place, to a very great extent, under the influence of electrical currents, and of change of temperature, even while the masses retain their solid form. chemical affinity has exhibited itself on the largest scale in the formation of the various mineral species of which the crust of the earth is composed; but we may also refer to the same cause the formation of divisional planes in rocks, the concretionary arrangement, and mineral veins. . _divisional planes._--it has before been stated, that the older rocks, in many cases, cleave freely in planes not parallel with the stratification. (see fig. .) in some instances, in beds of lava, a similar cleavage exists, sufficiently perfect to allow of its use as a roofing material. in these cases, there must have been a rearrangement of the particles, so that their axes of greatest attraction would lie in parallel planes; the same arrangement which exists in mica and other crystalline substances, which have one and but one free cleavage. a similar arrangement has sometimes taken place under such circumstances as to submit the process to more careful scrutiny. in the gold mines of chili, the powder from which the gold has been washed is "thrown into a common heap. a great deal of chemical action then commences; salts of various kinds effloresce on the surface, and the mass becomes hard, and divides into fragments which possess _an even and well-defined slaty structure_." when a portion of clay, worked into a paste with a very weak acid, is submitted to a weak voltaic action for several months, and then dried, it is found to have acquired a distinct though imperfect cleavage structure. it appears, then, that both electrical currents and ordinary chemical action are capable of arranging the particles of an earthy mass into separable layers. we may then regard this change in the older rocks as an imperfect crystallization, and probably induced by electro-chemical agency. it is also found that all rocks are divided into huge blocks by seams not parallel with the cleavage, and too regular to be considered as fractures. these seams bear an analogy to the secondary faces of crystals, which are never parallel to the cleavage. . _concretionary formations._--there exist in many rocks concretions which differ from the mass of the rocks. in most of the tertiary clays there are small concretionary nodules, which contain more calcareous matter than the mass of clay around them. in the coal formation, the nodular iron ore consists of concretionary masses. in the chalk formation, nodules of flint abound, and generally in layers. in many of these cases, particularly in the clays and coal, the nodules have an organic nucleus, and, although concretionary, they retain the marks of stratification of the adjacent rocks. hence they could not have been deposited in the form of nodules. there must therefore have been in the rock, though in the solid state, such motion among the molecules that particles of a particular mineral have separated from the mass and rearranged themselves in concretionary layers, yet so gradually as not to disturb the lines of original stratification. [illustration: fig. .] there are other instances, similar to the last in all respects, except that the segregated portion does not take the concretionary form. when gypsum is distributed in small proportion through a formation, there seems very little reason to doubt but that it is, by a molecular action, segregated from the strata in lenticular masses, as at a (fig. ). many of the limestone strata contain irregular aggregations of quartz. it is presumed that the siliceous and calcareous matter was deposited together as sediment, and that the aggregation has resulted from a movement among the particles similar to that by which the concretionary structure is produced. the columnar structure of basalt seems to have resulted from a peculiar molecular action, at first resembling a concretionary arrangement, while the mass was cooling from a state of fusion. in experimenting to ascertain the cause of this structure, mr. watt fused in a furnace seven hundred pounds of basalt. when cooled, he found that "numerous spheroids had been formed, and that when two of them came in contact, they did not penetrate each other, but were mutually compressed and separated by a well-defined plane, invested with a rusty coating. when several met, they formed prisms." (fig. .) [illustration: fig. .] . _mineral veins._--the phenomena of veins are such that they cannot all be referred to the same cause. in some, the vein-stuff has been protruded as a dike, differing from ordinary dikes only in the accidental circumstance that it contains a metal or a metallic ore. mineral veins are not, however, generally filled by injection from below. it is found that those veins only are productive which have an east and west direction. but injected dikes run in all directions. the ore often varies in richness at different depths in the vein, or passes into ore of some other metal. the ore also varies in kind and quality, according to the character of the rock through which the vein passes. these phenomena are best explained by supposing that the sediment of which the strata were formed contained the mineral substances of these veins in small proportion. after they were solidified, and fractures had been formed, the mineral substance was transferred by molecular action to the fissures, and deposited. it was shown by the early experiments of davy, that voltaic currents are capable of taking up mineral substances from their solutions, and removing them from one cup to another. it has been ascertained that in most mineral veins a proper apparatus will detect the existence of electric currents. it may be regarded as certain, that the unequal heating of different parts of the surface at the same time, by the sun, causes a vast current of feeble intensity to circulate around the earth once in twenty-four hours. the unequal distribution of heat below the surface may also produce currents subject to other laws. we should expect that these currents would take up the mineral substances diffused through rocks, and deposit them by themselves. it seems probable, therefore, that the molecular action, from which the segregation of metallic veins has resulted, was that of voltaic currents. section iii.--organic causes. the effects of all organic causes in producing geological changes are inconsiderable, compared with those of inorganic causes. with the exception of the coral formation, the most important of these effects are those produced by human agency. we find examples of this agency in the distribution of animals and plants beyond the regions where they are indigenous; in the increased numbers of certain species, and in the diminution, if not extinction, of others; in the modifications of climate, dependent on the destruction of the forests and the cultivation of the soil; in controlling the course of rivers; in arresting by embankments the encroachments of the sea; in breaking up and changing the place of great quantities of rock by mining and engineering operations; and in the increased quantity of sediment furnished to streams by cultivating the surface, and thus preventing the protecting influence which the matted roots of trees and the smaller vegetables would otherwise have. such effects, though attributable mainly to man, are produced in some degree by all other animals. besides these general effects, it is the existence of organic forms that has conferred on all the sedimentary rocks their fossiliferous character. _the records_ of the climate of each geological period, of the physical geography, of the vegetable productions, and of the animal forms by which the earth was peopled, consist in the remains of the living beings of these several periods, imbedded in the contemporaneous rock formations. but in the sediment deposited since the human era there must have been furnished both the remains of human beings and works of art, such as implements of labor and war, pottery, coins, fragments of ships, &c. moreover, the _quantity of material_ which has been furnished by organic causes is by no means small. the coal-beds are the product of vegetable growth exclusively. we not unfrequently find strata of great extent consisting almost entirely of the shells of molluscous animals, of the stems of encrinites, or of the shields of microscopic animalcules. but the most abundant rock which can be regarded as the product of animal organization is the _coral formation_. it consists of immense walls of coral limestone, separating either an atoll or the land of an island or continent from the open sea. the base of this wall has a width varying from a hundred feet to a mile or more, and the outer edge of it is at such a distance from the shore as to give a depth not much exceeding a hundred feet. over this area of the bed of the sea, which forms the base of the wall, the coral polyp commenced its work. attaching itself in immense numbers over this area, it deposits calcareous matter from its under surface, and thus, by degrees, elevates itself towards the surface of the water, till it reaches a level a little above low-water mark. the height of the wall would not, with these conditions, exceed one hundred feet; but some hundreds of the islands surrounded by coral walls are gradually subsiding. the depositions of the polyps keep pace with the subsidence, so that this wall has reached an elevation from its base of a thousand feet, and in one instance of two thousand feet. (see figs. , , , .) most of the islands of the torrid zone are thus surrounded with coral reefs, except a few where the cold polar currents reduce the temperature too low to admit of their growth. in one instance, along the north-east coast of new holland, there is a coral reef, some twenty-five miles from the land, which has a continuous extension, excepting occasional inlets of no great depth, of a thousand miles. the reef along the island of new caledonia is four hundred miles long. a large number of other reefs have a nearly equal extension. there is thus an area of several thousands of square miles covered to a great depth with this coralline limestone. some limestone formations of great extent among the older rocks were the work of similar animals. these lower forms of organization have, therefore, always been important geological agents, both in collecting the carbonate of lime from its solution in the waters of the ocean, and in depositing it as solid rock. section iv.--aqueous causes. water is, next to heat, the most important geological agent. all the stratified rocks are aqueous deposits, and their total amount is in some respects a measure of the influence which this agent has exerted. the materials have been obtained from the destruction of preëxisting rocks, transported by water, and deposited in layers. when the first strata were formed, the sediment must have been obtained entirely from igneous rocks, because only those rocks existed; but now it is obtained from every kind of rock which is exposed to abrading or decomposing agencies. hence, many of the later formations contain fragments, and sometimes within the fragments well-characterized fossils, of earlier formations. the sediment which is ultimately to become stratified rock is deposited on the beds of the ocean, and other great reservoirs of water. the formation of most of the aqueous rocks, therefore, as well as of the igneous rocks, is deep below the surface; and neither of these operations, on the large scale, is directly exposed to our observation. we may, however, learn by observation, how the sediment is furnished to the waters and transported by them, and we can form some correct ideas of the manner in which it will be laid down on the bed of the ocean, and solidified. i. _the furnishing of sediment._ . almost all the minerals which occur in the geological formations are, to some slight extent, _soluble in water_. hence, rain water, by passing through a stratum of earth or rock and reäppearing as a spring, loses the insipidity which it had as pure water, and becomes palatable. it is then found to hold in solution some small proportion of earthy substances, upon which this change of taste depends. although the proportion of dissolved matter is very small, yet the surface of earth upon which this distilled water is shed is one-fourth of the surface of the globe, and solution below all that surface is constantly taking place. no inconsiderable amount must thus have been furnished, from the existing rocks of each period, towards the formation of the strata of a later period. there are some substances which are soluble in water, in large quantities. _rock-salt_ is an example. it is not found in any very large proportion in rocks generally, but a very large aggregate amount has been taken up by the waters which have filtered through the strata. the ocean gathers into itself, by degrees, all the soluble substances which are thus taken up. it receives supplies of water charged with these substances from springs, rivers and lakes. it returns as much water as it receives; but it is always in the form of vapor, and is therefore pure water. hence the saline properties of the ocean, and of those inland seas which have no outlets. there is thus gathered the materials for the rock-salt deposits. but many substances which are not considered soluble in water become so by some modification of the water. water of a high temperature is capable of dissolving silex. in iceland and other volcanic regions, the hot springs are charged with silex, which is deposited as the water cools. thus, siliceous formations accumulate around springs of this kind. the various agates may have been deposited from such solutions. in the decomposition of mica, felspar and volcanic rocks, a considerable amount of potassa is set free. potassa or soda renders the water in which it is dissolved capable of dissolving silex in large quantity. in these ways water removes, with some degree of rapidity, one of the most insoluble minerals which rocks contain. in volcanic countries, and in coal districts, carbonic acid is abundant, both in spring-water and in the gaseous form. water charged with this gas becomes capable of dissolving limestone. where the water is exposed to the air, the gas gradually escapes, and the calcareous matter is deposited. many accumulations of this kind are now taking place. some have already extended several miles in length, and they are often of great thickness, in one instance, in italy, two hundred feet (fig. ). it is also probable that many calcareous springs issue below the surface of lakes and seas, and thus, both fresh-water and marine deposits would now be forming. these formations are distinctly stratified, and are white and crystalline, and become solid at the time of deposition. [illustration: fig. .] these dissolved materials are less observed than others, because they do not render the water turbid; but there is reason to believe that several of the aqueous formations, particularly the limestones, have been built up chiefly from them. . the _abrading action of rivers_ furnishes considerable detrital matter. the general form of the river courses is determined by other causes than the agency of the river itself, yet a river which has a rapid current is continually deepening its channel. we have proof of this by observing, when the water is low, that irregularity of surface which running water always produces, by wearing away the softer parts of the rock, and leaving the harder in relief. hence, a river will have its rapids either where the hardest strata occur, and which therefore wear down least rapidly, or where the rock has been hardened by the intrusion or near proximity of dikes. the abrading power of rivers occasionally becomes greatly increased by waterfalls. the force which the water acquires in its descent is such as to excavate a deep cavity at the foot of the fall, reaching back under the ledge from which the water descends. the ledge is therefore constantly being undermined. the cataract of niagara is peculiar, in having the rock at its base of a soft and friable texture, so that it is rapidly worn away, while the upper rock is a compact siliceous limestone. if the order of superposition had been the reverse, the falls would have been converted into a series of rapids. it is now preserved as a single fall, and as such it has probably cut the gorge, about two hundred feet deep and seven miles in length, through which its waters now reach lake ontario. a few years since, a large mass, perhaps half an acre in area, fell from the centre of the horse-shoe fall. another mass of equal size has recently fallen from the western extremity of the ledge. thus the fall is gradually receding. but the foreign substances, such as drift-wood, ice, sand and gravel, with which the waters of a river are occasionally charged, contribute more than everything else to its abrading power. at such times its volume is generally greatest, and its current the most rapid. its bed is then sometimes perceptibly deepened and widened in a few hours. much the greater part, however, of the earthy matter which rivers convey in such quantity to the ocean, is furnished by other means than the eroding action of the river itself. it is the loose material, the soil and alluvium, to which the solid rocks have been reduced by the imperceptible but incessantly operating atmospheric agencies, from which most of the sediment of rivers is obtained. after a rain, every tributary rivulet is turbid with suspended earthy matter, and it is from these sources that the larger streams receive the most of their sediment. some observations have been made for the purpose of ascertaining the quantity of sediment which rivers annually carry into the sea. the kennebec furnishes materials which, if spread evenly on an area of one mile square, and consolidated into rock of the specific gravity of granite, would have a thickness of six inches. the merrimac furnishes about two-thirds as much, the ganges about two hundred and fifty times as much, and the mississippi two thousand times as much. thus, the tendency is, to reduce the highest parts of the land, and to fill up the depressions of the sea; and though we have not data enough to form any reliable estimate of the total annual discharge of sediment into the ocean by rivers, yet they are sufficient to show that the effects of this kind are on a large scale, and to relieve us from any impression that existing agencies are inadequate to the production of the stratified rocks. . _the action of waves_ is another means by which detrital matter is furnished. wherever the shore consists of loose materials, and is favorably situated to be acted upon by the waves, there is annually a sensible encroachment of the sea. such encroachments are rapidly making in many places; and thus a large amount of sediment is delivered to the waters of the ocean. the waves also encroach upon the coast when it consists of rocks, even of the most indestructible kinds. they continually beat upon it, undermine the cliffs, and precipitate them into the sea. the tides increase the power of the waves, by varying the place of their action, so as to present the same surface of rock alternately to the action of water and of the air, frost and sun. during storms, the waves have sufficient force to break off fragments of rock from the escarpment, sometimes in masses weighing twenty tons or more, and remove them many rods inland. a bold, rocky coast always exhibits evidence of a great amount of erosion. the steep escarpments and the high rugged shafts of rock (fig. ) against which the waves now beat are the remnants of masses of rock which once extended further into the sea, but have been worn away by the waves. it is by such agency that the deep inlets and harbors of the coast of new england and nova scotia have been excavated. [illustration: fig. .] this more violent action of the waves is only occasional; but when of less power, they are incessantly rolling the loosened fragments of rock upon each other, and thus wearing them down to particles small enough to be carried away by the water. . the action of waves is confined to the coast, and never extends to great depths. but _marine currents_ act principally on the bed of the sea. the temperature of the mass of the ocean is much higher in the equatorial than in the polar regions. at the surface, the difference amounts to sixty degrees. the waters of the torrid zone are thus expanded, and flow over the colder waters of the north and south; while these colder waters of the polar seas flow back, in an under current, towards the equator. for the same reason,--a difference of temperature,--there will be, in the higher regions of the atmosphere, a current of warm and moist air flowing from the equator north and south, while the cold and dry air conies in from the polar regions towards the equator. in this way the equatorial waters are carried, in a state of vapor, towards the poles, where they are condensed, and go to increase the currents of water moving towards the equator. such are the general causes of the oceanic movements in a north and south direction; but these currents at once become deflected westward, by the diurnal revolution of the earth, as the trade winds do. hence there results a pacific equatorial current, which has a motion of about thirty miles a day, and an atlantic equatorial current, moving from sixty to seventy miles a day. the principal marine currents are shown in fig. . the currents moving towards the poles are superficial, and therefore do not produce any marked geological effects. but the polar currents, and those which are produced from them, are of great depth, and there is no reason to suppose that they do not move, from their commencement, along the bed of the ocean. there is also reason to suppose that they exist at great depths, where the opposing superficial currents entirely conceal them. wherever these currents come to the surface, their motion is undoubtedly greater than it is at the bottom, where it is retarded by the friction which the moving waters encounter, and by the irregularities of the bed of the ocean. it should, however, be remembered, that they move with the weight of the whole superior body of water; and therefore, though the motion be very slow, it will still possess great power. any irregularities in the bed of the ocean beneath such a current must be subject to very rapid abrasion. we shall sea hereafter, that earthquake vibrations often shiver the rocks at the solid surface; and if any of these ridges at the bottom of the ocean were thus acted upon, the loosened portions would be swept away by the current and deposited at lower levels, or where the current subsides. if, in any instance during an earthquake convulsion, a fault should be produced across one of these marine currents, like the great fault of over five hundred feet in england, the abutment thus thrown up would soon be worn down; and if it consisted of unconsolidated matter, it would be swept away almost bodily. [illustration: fig. .] the effect of such currents will be greatest where they are deflected by a continent or island. thus, a marine current sets from near new holland in a direct line to the north of the island of madagascar, where it is arrested by the african coast, and deflected into the narrow mozambique channel, and there acquires a velocity of four or five miles an hour. it is impossible that any kind of rock should receive the constant force of such a body of water without being rapidly worn away; and, if there should be any difference of texture in this rocky barrier, the softer portions would yield the most rapidly, and thus valleys might be formed. it is not improbable that the deep indentation on the western coast of africa may have been due, in a great measure, to the coast current from the cape of good hope; and that the caribbean sea and the gulf of mexico may have been excavated by the force of the atlantic equatorial current being thrown into this angle. we may regard these currents as oceanic rivers; and it is obvious that the volume of the terrestrial rivers would bear no comparison with that of these currents, and their effects would be equally small in the comparison. the gulf stream, and the mozambique and other similar currents, must be wearing down the valleys through which they flow, to such an extent as to furnish an immense amount of detrital matter for the formation of new rocks. it is principally to the agency of these deep marine currents that we are to refer those extensive denudations, so abundant on the present continents, such as the wearing out of the intermediate masses of rock between the hills already referred to (fig. ), the denudation of the connecticut river sandstone, and, perhaps, the excavations which have formed lake erie and lake ontario. ii. _the transportation of sediment._ the detrital matter obtained in these several ways is swept away by running water. the specific gravity of rocks does not, in general, exceed two and a half. hence, to keep them suspended in water, will require a force of only three-fifths of what would be necessary to suspend them in the atmosphere. in the case of river currents, the velocity and irregularity of motion are generally sufficient to keep all the finer sediment equally distributed. there will, however, be a division of the sediment according to the strength of the current. hence, the bed of a mountain stream, if there is any loose material, always consists of pebbles. as it approaches the alluvial region, the bed is sandy; and when the current becomes very sluggish, it consists of a fine mud. rivers never deposit all their sediment, some of them none of it, along their course. large rivers continue partially distinct from the ocean water to a considerable distance beyond their mouths. the waters of the amazon have been recognized at a distance of three hundred miles. this depends in part upon the volume and velocity of the river; more, however, upon the fact that river water is lighter than sea water. this extension of a river will, in most cases, be sufficient to deliver a part of its sediment into a marine current. when such a current sweeps very near the mouth of a river, as it does to that of the niger, the amazon, or the mississippi, it is probable that most of its sediment is carried away by it. the transporting power of a marine current is greater than that of a river, in consequence of the greater specific gravity of its water; but it has scarcely any of that irregular motion of rapid rivers, upon which their transporting power in a great degree depends. the force of the current alone, when it reaches the bottom, is, however, sufficient to remove every form of loose earthy matter. thus it may be presumed that the gulf stream sweeps all the sediment from its bed until it reaches the latitude of cape hatteras, where the cold waters from the north begin to underlie it, and it takes the character of a surface stream. but the transporting power of marine currents depends mostly upon the depth of water. it is found, by experiment, that ordinary river sediment will sink in water about one foot in an hour. a current, therefore, of a thousand feet in depth, which moves a mile in an hour, would carry its sediment a thousand miles. it is obvious, then, that there is no part of the bed of the sea which may not be receiving sediment. iii. _the deposition of sediment._ from what has been said of the weight of sediment, it follows that it will be deposited whenever the water in which it is suspended is at rest. hence, when a river increases in breadth so as to form a lake, the waters at the outlet are seldom turbid. the earthy matters with which the principal and tributary streams were charged all settle to the bottom, and go to lessen the capacity of the reservoir. thus lakes are continually diminishing in depth and area. in many instances, they are already filled with sediment, and are thus converted into alluvial plains, through which the river flows in a narrow channel. it is frequently the case that a river, as it approaches the sea, has so slow a motion that its sediment is deposited on the bed of the stream. thus the bed will be raised, and the banks will also be raised, by the deposition of sediment upon them at periods of overflow. the river will then be raised above the adjacent country. the river po, for the last part of its course, is from ten to twenty feet above the adjacent lands. the same is true of the mississippi, and many other rivers. the streets of new orleans are several feet below the surface of the river. in an uninhabited country, such a river would soon seek a new and lower channel; but in a populous country, it becomes a matter of interest and safety to confine the river in its old channel, by artificial embankments. but the principal part of the sediment of rivers is conveyed to the sea. it here mingles with the debris which the waves have furnished, and a part of it is deposited to form deltas. the remaining part is taken up by marine currents, mingled with the debris which they have furnished, and is spread out on the bed of the ocean. of the extent of these deposits we can form no estimate. those of rivers and lakes are comparatively unimportant, as they are in the older formations. some of the delta deposits are already of great extent. that of the ganges contains an area of twenty-six thousand square miles, that of the niger twenty-five thousand, and that of the nile twelve thousand. the delta of the rhone has increased its area by three hundred square miles in the last thousand years. the po has encroached upon the adriatic two thousand square miles in the last two thousand years, and the mississippi has enlarged its delta by one hundred square miles in the last hundred years. in the deep valleys of the ocean accumulations may be taking place on as large a scale as they ever have been in former times. iv. _character of the formations thus produced._ sedimentary matter thus deposited would take the form of _strata_. thus, a delta deposit may receive at one time from a river a layer of coarse gravel and pebbles, and in the course of a few hours the current may be so reduced that it will convey to the same place only fine sand and silt. or, if a depositing current receive its sediment only at intervals, the heaviest particles would be thrown down first, and the more finely levigated particles would continue to fall, till the water became transparent. another supply would furnish another similar stratum, and so on. the same arrangement might result from the sediment being furnished by different rivers. thus, if sediment were furnished to the gulf stream by the merrimac river, and the streams emptying into the bay of fundy, the freshets would occur earlier in the season in the merrimac, and it would furnish a supply of sediment from a region of primary rocks. a later supply would come from the red sandstone region of nova scotia, and the stratification would be indicated by the different kinds of rock produced. thus stratification will result from difference in the color, composition, or size of the particles of which rocks consist. a great variety of causes, both general and local, may therefore give to a deposit this character. hence, as stratified rocks are produced by the sediment now laid down from water, we may conclude that the older stratified rocks are the sediment deposited in like manner, in former times. the occurrence of layers of different composition, as one way in which the stratification is indicated, is produced by local and frequently recurring causes. there are, however, other alternations of much greater extent; those, for example, nearly twenty in number, distinguished by striking differences in lithological character, into which the new york system of rocks is divided. these alternations have resulted from more general causes. the physical geography of a wide region must have been so different, at the different periods during which these several formations were deposited, as to change, at each period, the kind of sediment furnished to the forming currents, and modify the types of animal life. we have seen that the same causes that determined the stratified arrangement will determine the alternations of strata of coarse and fine materials. it is obvious that the stratification of the marine deposits will be nearly horizontal. if the surface were very irregular upon which the deposition commenced, the irregularity would constantly diminish; for the movement of the water over this surface, however slow, would tend to remove the accumulations from the highest points, and leave them at the lowest (fig. ). delta and lake deposits will, however, dip somewhat, though never at a high angle, towards the deep water. in certain situations, where a river and a tidal wave, coming in conflict, cause, in succession, eddies and currents in opposite directions, we should expect to find the stratification very irregular (fig. ); sometimes false stratifications (_a b_), sometimes the strata cut off abruptly, and at other times contorted or dipping in opposite directions within short distances. [illustration: fig. .] wherever sediment is deposited, it will entomb whatever of the remains of animal or vegetable life may be mingled with it. they will be at once protected against the influence of all the ordinary decomposing agencies, and will continue for ages to retain their peculiar markings, and even their colors. they will thus constitute, in all future time, a record of the present condition of the organic world. the lacustrine deposits can contain only fresh-water species of animals, marine deposits only marine animals, while deltas may contain the remains of marine life mingled with those which have been washed down by rivers. the remains of birds, insects, and terrestrial animals, may occasionally occur, in every kind of deposit. sediment deposited in deep water will never contain fossils in abundance, the deep parts of the ocean being almost wholly destitute of animal or vegetable life. it is only in water of a few fathoms that the greater number of species and of individuals occur. in all these particulars the deposits now forming sustain a close resemblance to the older formations. [illustration: fig. .] there are certain formations, as that of the coal, which required conditions for their formation different from those of ordinary sedimentary deposits. coal consists of mineralized vegetable matter. its vegetable origin is proved by the uniform occurrence of vegetable fossils almost exclusively in the coal measures. when reduced to thin slices and examined under a high magnifying power, a structure very similar to the ligneous tissue of existing coniferæ is sometimes found to exist. there are probably vegetable deposits now taking place not altogether unlike those which produced the coal measures. we know that many rivers--the mississippi, for example--now carry into the sea great quantities of ligneous matter. before the country was inhabited by man, the quantity was undoubtedly much greater than it now is. it floats for a time; but the ligneous tissue itself is heavier than water, and as soon as the air is excluded from the pores, and they are filled with water, it will sink. the woody and earthy matters are swept into the sea together; but, as they sink under different circumstances, they will be deposited separately. _thus wood may continue to accumulate in particular places in the sea_ for long periods, with but little intermixture of earthy substances. it is, however, to be expected that, in the progress of geological changes, the places which at one time receive deposits of wood will at another receive detrital matter, and thus _the wood will become deeply buried_ beneath sedimentary strata. wood thus situated will become converted into coal. trees which had been covered to considerable depth with earth have been found near the mississippi river changed to lignite, a substance resembling charcoal. in this case, the wood had been exposed to no greater heat than is common to the crust of the earth at the depth where it was found; and yet it had undergone this change since the country has been known to europeans, as it retained the marks of the axe when it was discovered. it has also been found by experiment that vegetable matter, by long submersion in water, passes into the state of lignite. this is the first step in the conversion of wood into mineral coal. when lignite is exposed to moderate heat and great pressure, it loses the characters of lignite, and becomes mineral coal. this is shown by facts observed in germany, ireland and iceland, where beds of lignite have been overspread by basalt. the upper portions of the lignite are changed to mineral coal. the lower portions, which the heat did not reach, retain the characters of lignite. beds of vegetable matter, with a great thickness of rock deposited above them, would therefore be subject to all the conditions necessary to convert them into coal, namely, pressure from the superincumbent mass, and the heat which the strata uniformly assume at great depths. it is not improbable, therefore, that coal-beds are now forming, and that they have been formed at every geological period since an abundant terrestrial vegetation commenced. accordingly, there occurs in virginia an extensive coal-field in the oölite formation. coal-fields also occur in england, of less extent, in the same formation. in france, and other parts of europe, there are extensive beds of lignite in the tertiary formation. we have therefore no difficulty in accounting, in a general way, for the formations of the carboniferous period. the vegetables were probably less woody than those of the present time of equal size, and were therefore more easily prostrated and committed to the waters. they grew rapidly in moist ground, and perhaps in shoal-water, and required an atmosphere charged with moisture and of a high temperature. thus much is inferred from the conditions most favorable for the growth of recent species analogous to the coal-plants. these recent species are tropical plants, and grow in moist insular situations, conditions which would have existed at the carboniferous period, if the present coal-fields were then an archipelago dotted with low islands. such being regarded as the origin of the coal-beds, the _alternations_ of the earthy and carbonaceous strata may be referred, provisionally, to those great changes in physical geography upon which the other alternations of strata on a large scale depend. but the regularity with which the coal-seams and sandstone succeed each other presents some difficulties which, in the present state of knowledge, we cannot satisfactorily account for. _beds of salt_ occur, interstratified with other rocks, in nearly all countries. still, it is not a sedimentary deposit, and its formation must depend upon peculiar circumstances. in new york, saline, together with earthy matter, constitutes the onondaga limestone, one of the formations of the new york system. in kentucky, the strata of rock-salt are in the coal formation; in england, they are in the new red sandstone; in spain, they are in the greensand, and in poland they are in tertiary strata. the conditions of its formation have therefore existed in connection with the deposition of every fossiliferous rock. it has been shown that the ocean is the principal reservoir of the saline matters which are taken up whenever water percolates through rocks. it must happen not unfrequently, in the course of submarine elevations, that a basin of sea-water will be cut off from its communication with the sea; and from this basin the evaporation might be more rapid than the supply of water. the great salt-lake of utah is undoubtedly a basin of this kind. the mediterranean sea is another such basin, not yet wholly separated from the ocean. the evaporation exceeds the supply of water from the rivers, and a powerful stream is therefore continually thrown in from the ocean, through the strait of gibraltar. the waters of the mediterranean are already more highly charged with salt than ordinary sea-water. this sea may ultimately become a saturated solution, and begin to deposit salt. but whether it does, or not, it indicates the way in which salt-beds may be formed. v. _solidification of aqueous deposits._ sediment is generally deposited as a soft mud, but in nearly all the older formations it has become solidified. when rocks are deposited from a chemical solution, they take at once the solid form. such is the case with rock-salt and with limestone, when the material has been held in solution. solidification takes place in nearly the same way when water which holds carbonate of lime or oxide of iron in solution filters through beds of sand or gravel. the substance held in solution is deposited in the interstices till they become filled, and the whole is changed to solid rock. some rocks are composed of such materials that they _set_, like hydraulic cement, when they are deposited. other rocks become solid simply by drying. thus a deposit now forming in lake superior becomes, by drying, nearly as hard as granite. such a deposit will therefore become solid whenever it shall be elevated above the water. the pressure to which all but the upper layers are subjected is probably sufficient to reduce most rocks to the solid state. dry and pulverized clay is reduced by artificial pressure, for a moment, almost to stone. the pressure upon the deep-seated rocks is constant, and greater than any artificial pressure can be. in addition to these causes, all the older rocks have been subjected to a high temperature, some of them nearly to that of fusion. by this means the solidification of every kind of rock would be promoted, and probably some may have been reduced by it to the solid state, which would otherwise have remained as an incoherent mass. section v.--aqueo-glacial action. . _glaciers._--a glacier is a mass of ice occupying the bed of a mountain valley, having a slow progressive motion, and reaching somewhat lower in the valley than the line of constant snow. (fig. .) the glacier des bois, which may be regarded as a specimen of the alpine glaciers, covers an area of about seventeen square miles. in its lowest portion, when all its branches have become united into one stream, it has an average width of half a mile, and is five miles long. it is estimated that the glaciers of the alps cover an area of fourteen hundred square miles. these have been the most carefully studied, though glaciers are found in the valleys of various other ranges of mountains. in the higher valleys, the snow, which falls at all seasons of the year, accumulates in immense quantities, and the steep mountain sides contribute, by frequent avalanches, to this accumulation. the snow, when thus increased, does not become a compact, adhesive mass; but, changing into particles of solid ice, it resembles sand rather than snow. it is this _névé_ which constitutes the upper part of every _glacier_, and which, in a modified form, constitutes the lower part. the valleys descend rapidly towards the base of the mountains; and this snow-ice, having no cohesion between its particles, _moves slowly down the slope of the valley_, like a very imperfect liquid. after descending below the line of perpetual snow, the surface will melt during the day; and the water, sinking into the porous mass, becomes frozen, and converts the whole into more or less compact ice, yet never into a rigid mass. influenced by its own weight, and by the pressure of the snow-ice behind, it still continues its motion, and conforms itself to the shape and curves of the valley through which it passes. the average movement per annum may be stated at about five hundred feet. the temperature of the rocky bed of the valley will be a little, and but a little, higher than thirty-two degrees. there will therefore be but little melting at the bed of this river of ice. as it receives continual accessions from the atmosphere, it will therefore increase in volume till it descends to the level of perpetual snow. below this line _the waste exceeds the addition_; and as it approaches the lower and cultivated portions of the valley, it rapidly diminishes, till it finally loses the solid form, and becomes a rivulet. the terminus of the glacier is determined principally by the general climate of the country. any considerable variation of climate will cause it to recede, or descend lower down the valley. the terminus varies, however, somewhat with the seasons, being lower in winter than in summer, though the motion is much less in the cold season than in the warm; and it descends many rods further some seasons than it does others. the glacier consists principally of snow, more or less modified in structure; but it also contains whatever else may have been thrown upon its surface, or into the snows by which it is fed. tributary glaciers extend up through all the gorges into which the irregular surface of the mountain-top is divided. on these rough peaks there are always fragments of rock, varying in size from fine sand to masses weighing many tons; some of them loosened when the mountain was upheaved, some by subsequent earthquake vibrations, and others still by tempests, lightnings, and changes of temperature. when the snow has accumulated to a certain extent on the steep slopes, it falls in avalanches into the valleys, carrying with it loosened masses of rock, and often breaking off large fragments from the rocky escarpments against which it strikes. these avalanches are almost constantly descending, and hence a glacier always contains considerable _earthy matter distributed through it_. [illustration: fig. .] the friction of the glacier, at its edges and along its bed, separates more or less of the rock over which it moves; and hence there is always a layer of mud and pebbles under the glacier, and a line of loose fragments, called a _lateral moraine_, at the sides. when two glaciers unite, the two lateral moraines, thus brought together, come to the surface, forming a medial moraine, and show the line of junction sometimes for miles. the friction of the glacier on the bed of rock, assisted by the layer of pebbles, will wear down the prominent portions, and everywhere polish the surface. fragments of rocks may be frozen into the glacier at all depths. those which lie near the lower surface of the glacier would, by slight melting of that surface, project downward so as to act as a graver's tool on the rock over which it passes. hence, when the extremity of the glacier has receded beyond its ordinary limit, the surface of rock exposed is found, upon examination, to be _polished_, _striated_, and _occasionally grooved_ an inch or two deep. since the waste is almost wholly superficial, earthy matter, which was at first concealed in the mass of the glacier, is continually coming to view, as the surface melts and runs off. thus, none of the freight of the glacier is left along its course, but all is carried to its terminus and discharged there. hence, at the lower extremity of the glacier there is always an embankment of earth, pebbles, and boulders. if the glacier recedes a few yards at one season of the year, and leaves its earthy fragments scattered over this surface, they will be pushed forward into a ridge, as the glacier again advances. this ridge is called a _terminal moraine_, and consists wholly of substances which have been separated from the mountain mass, often at the highest beginnings of the glacier. at the terminus of all the alpine glaciers, there is a series of these moraines (_a a a_, fig. ) marking the successive limits of the glacier in former times. there is a ridge of boulders on the north side of the swiss valley, near the base of the jura mountains, resembling a terminal moraine. these boulders consist of several groups, distinguished by peculiarities of structure and composition; and each group lies opposite to the particular alpine valley which now furnishes the same kind of fragments. it has been thought that, at a former period of more severe climate, the swiss valley was filled in part with ice, and that the present glaciers extended across it to the jura mountains. it is found that the polished and striated surfaces of the rocks in the alpine valleys are precisely like the surface of the rock, which has not been exposed to atmospheric influences, in the north of europe and america. it has been proposed to extend the glacier theory, and account for these phenomena by supposing that the north polar regions were, at the ice period, capped with a glacier-mass, extending as far south as the drift phenomena appear. it is not to be doubted that the phenomena of polished surfaces and transported materials in the immediate vicinity of the alps, and near other high mountains, are correctly referred to glacial action. this theory has therefore solved, in part, one of the most difficult problems in geology; but there is great difficulty in extending it so as to account for the drift phenomena in general. if the motion depends upon gravitation only, the origin must have a much greater elevation than the terminus, which would not be the case in the great glacier supposed to extend southward from the arctic regions. elevation of temperature, it has been thought, might account for the movement of the mass southward. . _icebergs._--in very high latitudes, the ice, which makes out from the land into the sea during the cold season, suffers but little waste at any time. this sheet of ice continues to increase in breadth and thickness, by congelation, from year to year. the spray and the snows of each succeeding year will also add to the mass. it thus accumulates to the height of several hundred yards. it will also reach down a good many feet below the surface of the sea, and will extend back on the land, or lie heaped up against a precipitous escarpment, and firmly frozen to it. after a certain amount of extension over the sea, the accumulated weight of the ice and snow would tend to depress it, and break it loose from the shore. the waves would tend to the same result, and would act at greater mechanical advantage, as its extension from the shore becomes greater. _hence, it would ultimately become separated from the shore_, and float in the water. at its commencement, the earth, pebbles and rocks, which may lie along the shore, and as far down into the sea as the congelation extends, are frozen into it. in many situations its mass would be increased by avalanches while it remained attached to the land, and these would supply also masses of earth and rocks, as they do to glaciers. when it becomes loosened from the shore, it will break off, and carry with it some of the earthy portions of the coast, or the less firmly fixed masses of rock from the escarpment against which it formed. thus every iceberg becomes _freighted_, more or less, _with earth and rocks_. this has almost uniformly been found to be the case, when they have been landed upon by ships' crews and examined. we have seen that the general tendency of the waters of the ocean, and of the lower stratum of the atmosphere, is to a motion from the poles towards the equator. however irregular, therefore, the course of an iceberg may be, its general _movement_, influenced both by the prevailing winds and by ocean currents, will be _towards the equator_. [illustration: fig. .] these floating ice-mountains (fig. ) are formed in _great numbers, and of vast size_. the relative specific gravity of ice and water are such that nine cubic feet of ice, below the surface of water, will support one cubic foot above it. as icebergs are often one or two hundred feet high, their vertical depth must be a thousand feet at least; and their area is equal to a square mile, and sometimes it is much greater. in , the united states exploring expedition, in the extreme southern ocean, coasted for eighty miles along a single iceberg. they are never absent from the polar seas; and at certain seasons they are so abundant along the usual course of vessels from new york to liverpool, as greatly to obstruct and endanger navigation. an iceberg may continue for some time to increase in size, while floating in the polar seas, but will at length reach a latitude where the waste will exceed the additions, in consequence of the temperature both of the air and of the water. it will, therefore, drop gradually the earthy matters which it contains, upon the bed of the ocean. it is not improbable that icebergs may often reach down so far as to strike the highest points of the bed of the sea. the ice would be lifted, and glide over the elevation, without suffering any perceptible deviation from its general course. it would thus affect the surface of rocks exactly like a glacier. if, however, the iceberg becomes permanently stranded, and melts in one place, its earthy matters will be thrown down upon the elevation which first arrested it. if the bed of the sea, between the fortieth and sixtieth degrees of latitude, could be exposed for examination, the rocky surface would be found to be polished and striated by the icebergs which have passed over it, and the whole surface would be strewed with boulders and drifted materials brought from arctic and antarctic lands. sometimes it would be accumulated in heaps, and sometimes spread nearly over the surface. we have seen that very recently, probably about the close of the tertiary period, the portion of europe and america over which the northern drift is found, has been depressed several hundred feet. it may be presumed that at that time icebergs floated over it, polished the surface of the rocks, and distributed the boulders and other drift which is now found upon it. section ii.--igneous causes. i. _of the temperature of the mass of the earth._--heat has been the most efficient agent in determining and modifying the structure of the earth; and, in order that the explanations of the phenomena referable to this cause may be intelligible, some idea must be formed of the actual present condition of the mass of the earth with respect to heat. at any point of the surface there are variations of temperature, depending on external causes. but these variations are found to extend only a little way below the surface,--never more than a hundred feet. at greater depths, it is found that the temperature invariably increases with the depth. deep mines have always a temperature above the mean annual temperature at the surface. the water obtained by deep boring is always tepid when it comes to the surface. the thermal springs, so abundant in this country and in europe, are so situated as to justify the impression that their waters come from great depths. to make these general observations of any value, we must determine the law by which the temperature increases. the result of all the observations yet made, in mines and upon wells and springs, is that, below the first hundred feet, the temperature increases by one degree of fahrenheit's scale for every forty-five feet. regarding this law of increment as applicable to all depths, at ten miles below the surface we should have a temperature above that produced by the combustion of wood; and at twenty-five miles, a temperature of three thousand degrees, by which nearly all mineral substances would be reduced to a state of fusion. the general conclusion of a temperature sufficient to melt the mineral substances of which rocks are composed, at no considerable distance below the surface, is confirmed by the fact that portions of the interior of the earth--at least, at the volcanic centres--are in a melted state. the intimate connection between some volcanoes situated a hundred miles or more apart, so that they are alternately in a state of activity and rest, indicates that these centres are connected,--that subterranean melted lava extends from one to the other, so that when one is active, the elastic force is relieved at the other. these deep-seated lakes of lava must therefore underlie large areas. we are justified, then, in concluding that the mass of the earth, with the exception of a comparatively thin superficial layer, has a very high temperature. by way of accounting for this temperature, it is now generally assumed that the earth was originally in a state of fusion; that it was a mass of liquid lava (if, indeed, it had not a temperature sufficient to reduce it to the aëriform state). starting with this assumption, there must necessarily be a gradual reduction of temperature by radiation, and a time must arrive when the surface would be crusted over with solidified lava; and this crust would increase in thickness as the cooling advanced, the interior still retaining its heat and liquidity. the present condition of the crust of the earth, its form, that of an oblate spheroid, with the exact difference of the equatorial and polar diameters which is found to exist, as well as the phenomena of volcanic eruptions, will all admit of explanation on this hypothesis. it has, however, been rejected by some; and, to account for the heat of the interior of the earth, it is suggested that, if the bases of the earths and alkalies, particularly potassium, sodium and calcium, exist in their metallic state beneath the surface, the rapid oxidation of them by the access of water would generate heat of sufficient intensity to melt the oxidized materials, and thus account for the phenomena attributable to heat. either of these hypotheses may be adopted; but it is not necessary to account at all for the existence of this temperature. the fact is susceptible of proof; and, though we may not be able to frame any hypothesis to account for its existence, we may yet employ the fact in the explanation of other phenomena. ii. _the action of internal heat in producing volcanoes._ the phenomena of volcanoes and earthquakes are evidently produced by some force operating from below. the effect of heat alone would be to reduce the rock to a liquid state. there is no reason to suppose that it is ever sufficient to reduce them to the aëriform state. the elastic force must therefore depend upon some other substance associated with the lava, and this substance is water. this will be shown by an examination of lavas. at the time of their ejection, they are in a fluid or semi-fluid state; but it is not a complete fusion. even the most fluid lavas contain particles of minerals in a solid state. the liquidity depends upon the fusion of the more fusible portions, and upon the steam of water at a high temperature, which fills the interstices between the solid particles. the porous character of cooled lavas is produced by the steam which filled the cavities previous to solidification. steam always escapes from the surface of a lava current while it is cooling, and it is always discharged in immense volumes from the orifice of eruption, in connection with the lava, and especially at the close of an eruption. the geographical position of volcanoes, also, leads to the conclusion that water is essential to their activity. there are five principal lines of volcanic activity. one, commencing at the southern extremity of south america, extends northward along the andes and cordilleras to california or oregon. the second has a north-east and south-west direction, from the aleutian islands through the kurule, japanese, and philippine islands, till it meets the third line, lying in a nearly east and west direction, embracing sumatra, java, and most of the pacific volcanic islands. a fourth band commences in the grecian islands, and extends westward so as to include the volcanoes of italy and the adjacent islands, and the azores. the fifth band embraces the volcanic islands of the west indies, crosses mexico in about the latitude of the city of mexico, and extends into the pacific. there are also some isolated centres of volcanic activity, such as iceland. these volcanic bands embrace about three hundred volcanoes. it will be seen that they must nearly all be in close proximity to the ocean, or to large seas. about two-thirds of them are on islands. moreover, the volcanic vents which are wholly submarine are probably very numerous. this circumstance of the position of volcanoes establishes a presumption that they cannot exist at a distance from some large body of water; and, taking it in connection with the constant presence of aqueous vapor in lava, we are justified in the conclusion that _the presence of water is an essential condition of volcanic activity_. knowing that heat and water exist at the volcanic centres, it is not difficult to form an idea of _their mode of operation_. the water, diffused through the interstices of the lava, and subjected to a temperature sufficient to melt the lava, would possess an _elastic power_, which, though never computed, we may well suppose capable of overcoming any resistance which the crust of the earth might present. the repressing force will be the tenacity and weight of the superincumbent strata. whenever the elasticity is superior to this repressing force, it will manifest itself in the fracture of the strata, and often in the ejection or lava to the surface. this fracturing of the strata, produced by an uplifting subterranean force, is believed to be the cause of the noise and the vibratory motion which are the chief phenomena of earthquakes. the elastic force may raise lava to the surface, and thus the fracture would become a volcano. but the force may expend itself by the discharge of vapor into the fissure, or by merely filling it with lava. in either case, the only evidence of the existence of the volcanic force would be the noise and the wave-like motion experienced at the surface. the cause of the volcano and earthquake is therefore the same, though the phenomena which characterize them are different. when the strata are is thus fractured, lava may for a time be discharged along the whole line. by the cooling of lava in the fracture, it would become partially reunited. still, this would be the line of least resistance. it would therefore be again burst through in certain places, which would long continue to be orifices of discharge, and thus the original fracture would determine _a line of volcanic activity_. the repressing force may become greater at an orifice of eruption than at some other point, either by the great accumulation of ejected materials around the opening, or by the dormancy of the volcano long enough for the complete solidification of the lava with which the channel was filled. the least resistance may then be far from any previous vent, when a new orifice of discharge will be opened, and _a new volcano make its appearance_. it seems probable, also, that volcanoes may become extinct by the reduction of temperature at the volcanic centre, and that new volcanic centres may be formed; but the cause of this change of temperature is not yet well understood. new volcanoes have broken out in the sea, near iceland, in several instances; others in the volcanic line east of asia. graham island, situated between sicily and africa, was formed by an eruption which broke out in the bed of the sea where the soundings were more than one hundred fathoms. the island was at one time two hundred feet 'above the sea, and three miles in circumference. it was, however, gradually destroyed by the action of the waves, and now remains a dangerous reef, covered by less than two fathoms water. the volcano of jorullo, in mexico, was formed in this way. previous to the formation of the mountain, the region where it now is was a cultivated table-land. during the year volcanic action commenced and continued, until, at the expiration of twelve months, a cone had been formed having an elevation of sixteen hundred feet above the adjacent plain. an orifice of eruption is at first but little elevated above the general surface; but, by the accumulation of ejected matter, a cone is at length formed around the vent. the upper portion of a cone always consists of these materials, but there may also be in progress a general elevation of that part of the earth's crust, and the cone will partake of that general elevation. the cones of the andes owe their height, in a great measure, to a general movement of elevation; those of Ætna and vesuvius, in a greater degree, to accumulation of ejected matter. in either way, the height may become so great that the force necessary to raise a column of lava to the top would be greater than the sides of the cone, weakened as they always are by fractures in all directions, can sustain. hence, the highest craters of Ætna and south america have long been closed, and the lava escapes through fissures at a lower level, and _lateral cones_ are produced. [illustration: fig. .] the form which the materials have, when ejected from volcanoes, depends mainly upon the degree of liquidity of the lavas at the volcanic foci. if the liquidity is very perfect, the aqueous vapor will readily rise through the lava. the steam thus separated will drive before it whatever rocks, or previous lavas, may obstruct it. in their progress they would be reduced to sand and powder, and ejected as _volcanic cinders_. (fig. .) if the lava possess considerable viscidity, the aqueous vapor will separate with more difficulty, and the lava and vapor will ascend the channel together. large bubbles of vapor will, however, collect with more or less of frequency; and, as they rise through the lava, will drive forward a portion of it, and cause the overflow to take place by pulsations. as the bubbles reach the surface, their bursting causes the loud reports, which are compared to the discharge of heavy artillery. with each explosion some of the lava will be projected violently into the air, and, cooling, will fall to the surface as scoriæ,--or, if the lava be highly vitreous, it will be drawn out into fibres, and descend as volcanic glass. iii. _geological phenomena referable to volcanic action._ volcanic agency has probably never been less than it is now, and we ought therefore to find its effects very general and important. . the most obvious of these effects are the _fractures_ with which the crust of the earth is everywhere intersected. the uplifting force upon which all volcanic phenomena depend would necessarily fracture the crust, and the wave-like motion resulting from the fracture would cause numerous secondary fractures, having a parallel direction. they are often of such extent, during earthquakes, as to endanger life. during the great earthquake at lisbon, in , a fracture opened of sufficient width to swallow up the quay, and several thousands of persons who had fled there for safety. the chasm remained permanently open to the depth of six hundred feet. the earthquakes with which the valley of the mississippi was visited in so often fissured the surface, that the inhabitants protected themselves by clinging to the trunks of trees, which they felled transversely to the direction of the fissures. [illustration: fig. .] the first fracture which is produced by the upheaving force will open upwards, and scarcely reach down to the seat of the force. but there will be other parallel fractures, dependent upon the first, and opening downward. thus, the primary fracture at _a_ (fig. ) will be at once followed by the fracture _b_, opening toward the lava, which will be injected into it, and which, on cooling, will form a _dike_. their formation is mostly concealed from observation, but not always. during the eruption of Ætna, in , numerous fissures opened, one of which was six feet wide and twelve miles in length; and the light emitted from it indicated that it was filled with lava to near the surface. the process was as perfectly seen as from the nature of the case it could be. . the conversion of the lower sedimentary strata into _metamorphic rocks_ has been effected by volcanic heat. the material of which dikes consist has been injected in a highly-heated state; and, by observing the effect which they have had upon the adjacent rocks, we may judge of the effect which subterranean heat must have upon the lower mechanical strata. wherever the dikes are of considerable thickness, they have converted the adjacent shales into primary slate, the sandstones into quartz rock, and the dark and friable limestones into granular marble, and destroyed the organic impressions. in the southern extremity of norway there is a district in which granite protrudes in a large mass through fossiliferous strata. these strata are invariably _altered_ to a distance of from fifty to four hundred yards from the granite. the shales have become flinty, and resemble jasper; and near the granite they contain hornblende. the siliceous matter of the shales has become quartz rock, which sometimes contains hornblende and mica, and therefore constitutes a kind of granite. the limestone, which at points remote from the injected rock is an earthy, blue, coralline limestone, has become a white, granular marble, near the granite, and the corals are obliterated. the altered shales and limestones in many places contain garnets, ores of iron, lead, &c. the annexed (fig. ) is a plan of this granite and altered rock. [illustration: fig. .] one of the most instructive examples of metamorphic action in this country is found in the white mountains of new hampshire. these mountains have, till recently, been thought to consist principally of granite; but it is now ascertained that this supposed granite is an altered rock of the silurian period. it is represented as "intersected by veins of felspathic granite; and the general mass is itself in many parts converted into a near approximation to a binary granite, composed of distinctly developed quartz and white felspar, with a few sparsely scattered specks of mica. in its weathered surfaces it wears a close resemblance to some fine-grained granites; but, upon inspecting a fresh fracture with a magnifier, we instantly perceive many rounded grains of quartzose sand, and the felspar is imperfectly formed, though the mica has more nearly reached the condition which it has in granite. in some of the coarse varieties of this white rock, small rounded pebbles of quartz are to be seen, giving unequivocal evidence, even to the naked eye, of its being an altered sandstone. we feel no hesitation in deciding it to have been a silico-argillaceous white sandstone, now almost granitized by extensive metamorphic action." similar illustrations, on a small scale, may be seen in every country where the strata have been cut through by intrusive dikes. sir james hall has shown the same by actual experiment. he exposed pulverized chalk to heat sufficient to melt it, and under sufficient pressure to prevent the escape of the carbonic acid. after cooling, the chalk was found to have taken the form of crystallized limestone. but instances enough have been given to show what changes should be looked for wherever the sedimentary rocks have been exposed to a high temperature. the lower strata must have been exposed, for long periods of time, to such a temperature. we do not know at what depth below the surface of the earth the rocks become liquid; but above the line of actual fusion there must be a mass of rock not melted, yet scarcely retaining the solid form. for a great thickness, perhaps for several miles, it would be in a more or less yielding state. as there is not actual fusion, the stratification is not destroyed, but such a degree of mobility among the particles exists, that some degree of crystallization takes place, and the elastic forces below easily bend, throw into folds, compress, and in every way contort these strata. at the same time, any organic matters which they may contain are decomposed, and the impressions of them are obliterated. and such is the condition in which the metamorphic strata are actually found. . _denudation_ is, in a great measure, dependent on volcanic action. it results from the billowy motion peculiar to the earthquake. this is not simply a violent horizontal motion, but an equally violent vertical one. it is a series of waves,--a succession of alternate elevations and depressions of the solid crust. the height of these waves can only be judged of by their effects; but it is difficult to account for some of these effects, without supposing the waves to have been several yards in height, and their velocity, in the few instances in which the time has been accurately determined, was twenty miles a minute. that such earthquake waves actually exist there can be no doubt. during the earthquake in calabria, in , the flagstones in many of the towns were lifted from their places and thrown down inverted, and trees bent so that their tops touched the ground. during the great earthquake in chili, in , the walls of houses, which were parallel to the line of oscillation, were thrown down, while those that were at right angles to it, though greatly fractured, were often left standing. wherever careful observations have been made, during and after severe earthquakes, analogous facts have been noticed. persons are generally affected with sea-sickness. the sea is violently agitated. it often retires to an unusual distance, and then returns upon the shore with most destructive waves. incredible, therefore, as it may seem, that the solid crust of the earth should be thrown into such wave-like undulations, the fact is well established. with a velocity of twenty miles an hour, the successive waves may be some miles apart, and yet be sufficient to account for all the phenomena. it is evident, therefore, that the curvature of the wave will be very slight, and yet enough to break into fragments all the rocks thus curved. during the earthquake in chili, before referred to, "the ground was fissured, in many parts, in north and south lines. some of the fissures near the cliffs were a yard wide. many enormous masses had fallen on the beach. the effect of the vibrations on the hard primary slates was still more curious. the superficial parts of some narrow ridges were as completely shivered as if they had been blasted by gunpowder." similar phenomena seem everywhere to be exhibited by earthquakes. it may be presumed that almost all parts of the earth have, at different periods, been subject to these earthquake waves. accordingly, we find that the crust of the earth is nowhere in an entire state, but is divided by irregular lines into comparatively small fragments. by this means, the deep fissures produced by fractures opening upwards would be filled with fragments of rock shattered from the uplifted edges. in this way the boulder masses were originally loosened from their parent beds, and exposed to the action of ice, or any other transporting agencies. in the same way the rocky bed of the ocean is, to a considerable depth, reduced to a disintegrated mass. in this condition it will be rapidly removed by marine currents, more or less broken, worn and comminuted, by the movement, and deposited elsewhere. the materials have thus been furnished for a very large proportion of the sedimentary rocks, and especially of those which are composed of distinct fragments of other rocks. by this means, also, wherever the rock formations come to the surface, they are so broken that limestone, sandstone or granite, suitable for architectural purposes, is seldom found, except at considerable depths. this fragmentary condition of the surface rock is such as exposes it to be acted upon readily by any powerfully abrading causes, or to be more rapidly disintegrated by atmospheric and aqueous causes. . we have already assumed that one principal division of rocks--the unstratified--is of igneous origin. we have the proof of actual observation, that lavas, and the accompanying _tufas_ and _grits_, are volcanic products. the peculiarities of these products, in situation, structure, and form, and in the imbedded minerals, are so great, that whenever we find these peculiarities in the rocks of a country not now volcanic, we still regard these rocks as of volcanic origin. we thus have lavas, as well as stratified rocks, of different ages. there has probably been no time in the earth's history when they have not been forming. the _trappean rocks_ are also of igneous origin. it is evident, from their occurring in the form of dikes, that they have been in a melted state. as they rest upon rocks of a sedimentary origin, they must have been thrown up by volcanic forces. yet they differ from ordinary lavas. they are not vesicular in their structure, are more crystalline, and there is in no case evidence that they have flowed from craters. if we regard them as the lavas of submarine volcanoes, we shall have conditions which will account for all their peculiarities. at a certain depth the pressure of the water would be sufficient to prevent the formation and escape of vapor, and therefore the lavas thus ejected would not be vesicular. as the rapid cooling of lavas depends, in a great degree, upon the escape of watery vapor, submarine lavas would cool slowly, in consequence of the pressure. the liquidity depending in part upon the retention of the heat, and in part upon the retention of the aqueous vapor, they would consequently remain in a liquid state much longer than the lavas of sub-aërial volcanoes. they would therefore take a more highly crystalline form. all the loose materials thrown out during the eruption would be removed by oceanic currents, and hence no cone would be built up around the orifice of eruption. we may therefore regard the trappean rocks as the lavas of submarine volcanoes. the present volcanoes of this kind are necessarily producing the same kind of rocks, though there will be no other proof that they exist, except the existence of the volcano, till the bed of the sea becomes dry land. the _granitic rocks_ are also the product of igneous causes. granite is the most abundant of these crystalline rocks; and the others, such as crystalline limestone, are so intimately associated with granite that they must have had the same origin. granite is everywhere found to send off dikes into the overlying rocks, and must therefore have been in a state of fusion; that is, it must have existed as lava beneath the surface. it is obvious that fluid lava always exists in great quantity beneath areas of energetic volcanic activity. portions of this lava must in succession take the solid form. wherever the surface is elevated along a line of fracture, the lava which is accumulated beneath rises above the level of the general reservoir of lava, and will therefore part with its heat more rapidly. on cooling, it becomes the granitic nucleus of the mountain. we ought also to suppose that, by the extremely slow process of the transmission of heat to the surface, the crust of the earth is everywhere increasing in thickness; that is, the upper portion of the great lava mass is solidifying. sir james hall has shown, by experiment, that earthy substances, reduced to a state of fusion, become more highly crystalline as they are allowed to cool more slowly, and are subjected to greater pressure. it is difficult to conceive of these conditions existing in a higher degree than they do in the cooling masses of lava below the stratified rocks. these lavas must therefore take the highly crystalline form which the granitic rocks are found to have. all the igneous rocks have therefore existed as subterranean lavas. the volcanic rocks have become vitreous, the granitic are crystalline, and the trappean are intermediate in structure, coinciding with the circumstances of pressure and rate of cooling under which they have severally been formed. . _the elevation of mountains_ is another result of volcanic action. the height of mountains depends, in part, upon general elevation. yet there is a different action, upon which the existence of the mountain, as such, depends. whenever igneous action becomes intense under any portion of the earth's surface, and the elastic force greater than the repressive, the solid crust will be broken and raised up, and along this line of fracture the lava will rise above its general level elsewhere. this lava, thus lifted out of the general mass, in time solidifies, and forms the nucleus of a mountain. at successive periods the elevating force is renewed, and adds somewhat to the mountain mass before supplied. in this way the mountain is ultimately formed. so far as observations have been made, the elevation of mountains seems not to be gradual, but spasmodic; and yet the elevating force probably accumulates constantly and uniformly. the repressing force consists of the weight of the strata above, which may be regarded as constant, and their strength, which is variable. when the elevating force becomes greater than both the repressing forces, the crust is fractured. the strength of the strata then becomes nothing, and the repressing force is the weight alone. the elastic mass below at once expands, and the requisite space is furnished by the uplifting of the strata along the line of fracture. as the ridge of lava which fills this additional space cools, it recloses, in part, the original fracture, and the repressing force again consists of the two elements,--weight and strength. there will therefore be no further elevation till the elevating force is again superior to these two forces. thus the elevating force, though it may accumulate at a uniform rate, will manifest itself only at considerable intervals. as the accumulation of lava along the line of fracture is the cause of the upheaval, every mountain must have a central granitic axis. sometimes this granitic mass is pushed up through the fissure, as in the case of mont blanc. at other times, the stratified rock, which formed the original surface, is carried up so as to form the surface rock nearly to the top. in either case, the strata are lifted along the line of fracture, and left in an _inclined position_. in this position the older rocks are always found, wherever there has been any considerable amount of igneous disturbance. in some instances, the additional space required by the expansion of the igneous mass below is furnished, not by the uplifting of the strata, but by their compression into folds between two lines of upheaval. the igneous rock is elevated but little above the stratified through which it had burst; but the stratified rocks have taken the undulatory form, and the widening of the igneous mass along the lines of fracture has compressed the undulations, until the planes of _the strata have become vertical_. fig. will give an idea of the successive changes by which the vertical position of the strata has been produced. [illustration: fig. .] the force by which mountains are elevated being the elasticity of the vapor diffused through the subjacent lava, it may happen, if the lava have a high degree of fluidity, that this vapor will collect in large masses, and rise as far as the lava is in a fluid state. the irregular flow of lava from craters during an eruption is undoubtedly due to the rapid ascent of such steam bubbles through the lava. such an accumulation of vapor under a mountain mass, if it cannot escape, would support it as long as the temperature remained unchanged. but, upon a reduction of temperature, the mass which had been upheaved by it would be unsupported, and liable at any time to sink. instances of _subsidence_ on a comparatively small scale will admit of explanation in this way. papandayang, one of the loftiest volcanic mountains of java, sunk down four thousand feet in the year . the area engulfed was sixteen miles long and six broad. the crater of kilauea, in one of the sandwich islands, was evidently formed in this way. it is situated on the side of a mountain, and consists of a chasm eight miles in circumference and a thousand feet in depth. liquid lava can always be seen boiling in the small craters at the bottom; and at times it rises so as to overflow them, and fill the chasm to within four hundred feet of the top, when lateral subterranean passages are opened, by which it is discharged. the same explanation--a depression of the central portion--may be given of the formation of the large craters in the canary and grecian islands. it is also probable that lake avernus and others, in italy, and some in germany, have had a similar origin. the subsidence of papandayang is of importance as a historical fact; and it is not at all unreasonable to suppose that larger chasms of great depth were also sudden subsidences of a similar character. lake superior has a depth considerably greater than the elevation of its surface above the level of the sea. the bottom of the dead sea is two thousand six hundred feet below the surface of the mediterranean. and at one place in the atlantic ocean a sounding was attempted with more than six miles of line, without reaching bottom. these sunken areas, however, though of great extent, occupy only an insignificant portion of the entire surface of the earth. . _the elevation of continents._--the causes of change of level which have been given will not explain those _slow vertical movements_ which are now taking place in greenland and the north of europe, or those by which the present continents have been elevated and the bed of the sea depressed. any cause which will account for these movements must be one operating for long periods, under large areas, and with great uniformity. the cause which fulfils all these conditions most satisfactorily is a _variation of temperature_ in the mass of rock underlying the portion of the surface whose level is changing. it has before been shown that the temperature increases as we descend below the surface; but there is also reason to suppose that it undergoes great variations. the volcanic grits interstratified with the silurian rocks of england show that at the silurian period volcanic fires were active below that portion of the surface. when the early fossiliferous rocks of this country were deposited, the alleghany mountains had not been elevated; but before the tertiary period they had taken nearly their present form. some portion of the intermediate period was therefore one of volcanic upheaval. the trappean rocks are also evidence of intense volcanic action existing here. france, during the tertiary period, was a highly volcanic country; but all volcanic activity has now subsided. the andes have been mostly elevated since the tertiary period, and are still rising. it is evident, then, that at different periods volcanic heat may vary from its highest to its least degree of activity, below any portion of the earth's surface. this variation of temperature must be followed by variation of volume of the earth's crust; that is, it _must produce expansion or contraction_. experiments have been made, under the direction of the united states government, to determine the expansion of the several kinds of rock used in our public works. it was found that granite expands nearly one two hundred thousandth of its length for every degree of increased temperature, limestone somewhat more than that, and sandstone about twice as much. taking the expansion of the granite as the basis of calculation, and supposing the crust for a hundred miles in thickness to be undergoing change of temperature, there would be a resulting difference of level exceeding two and a half feet for each degree of change in temperature, or more than two thousand five hundred feet for a change of one thousand degrees. this calculation is made upon the supposition that the law of expansion is the same for all temperatures, and that no new conditions are introduced at high temperatures by the presence of aqueous particles. we know, however, that solids expand more rapidly at high temperatures than at low, and the elasticity of aqueous vapor at high temperatures must increase the rate of expansion of the rock through which it is diffused. although we are not able to introduce, numerically, the effect of these two circumstances, yet it is obvious that they must be considerable. the mean elevation of land above the level of the sea is about nine hundred feet, the mountain masses above that level not being included; and the estimated mean depth of the ocean, not including its chasms, does not exceed two thousand six hundred feet. the _total elevation of the continental masses_, for which it is necessary to account, does not therefore exceed three thousand five hundred feet. this amount of vertical movement may evidently be produced by the expansion and contraction resulting from changes of temperature. these changes of level must, however, be very gradual. any diminution of temperature must result from the transfer of heat to the surface; and the conducting power of rocks is very imperfect. the lava in a crater is often so cooled on the surface that it can be walked on, while but a few feet below it is still liquid. lava currents continue in gradual motion long after the surface is nearly cold. this was the case with one of the currents from Ætna for more than nine months after its eruption, and with another for ten years. humboldt visited jorullo forty years after it was thrown up, when the lava around the mountain was still in a heated state, the temperature in the fissures being on the decrease from year to year; but twenty years after its ejection the heat was still sufficient to light a cigar at the depth of a few inches. if so long a period is insufficient to solidify a comparatively small quantity of melted rock when the circumstances for cooling are most favorable, we may well suppose that centuries would be required to abstract sufficient heat from the earth's crust to produce any material change in the areas of continents. if this account of the elevation and subsidence of continents is correct, it would seem that they ought to be constantly undergoing change of level. and their _apparent stability_ may be regarded as an objection to it. if in any place there is absolutely no vertical movement, then those conditions must exist in which, for the time being, there is no change of temperature. but it is doubtful whether there ever is absolute stability of any portion of the surface for long periods of time. of the minor vertical movements of the interior of continents, there can, from the nature of the case, be no evidence whatever. changes of level, where they are known to be taking place, are so slow, that they are hardly perceptible in the period of a human life. such changes had been going on for centuries in sweden before they were suspected. as accurate observations have increased in number, and historical records become available, it is becoming known that a very large amount of the seaboard is undergoing change of level. it becomes probable, then, that these extremely slow changes of level are constantly and everywhere taking place. that portion of the crust of the earth constituting the present continents, being further removed from the centre, would part with its heat more rapidly, and receive heat from the central mass more slowly, than that portion which at present constitutes the bed of the sea. the continents are therefore in a situation to undergo contraction and depression, and the bed of the sea is most favorably situated for rising. if the distribution of water through the mass has any influence in promoting its expansion, then the bed of the sea would receive this supply most abundantly, and the continents the least so. we see, then, in nature, those provisions for an alteration of level, which, from the character of the several rock formations, we know to have taken place. when any portion of the earth's surface is covered with the sea, the conditions exist which will at length elevate it. when it becomes dry land, the conditions exist which will in time depress it below the level of the ocean. hence, those impressions in regard to the land, as stable beyond the possibility of change, we ought to abandon; and those vertical movements, which, when proved, we are accustomed to regard as extraordinary, we shall, at length, consider as only particular instances of one of the most general laws of nature. . _variations of climate._--the only sources of heat by which climate can be affected are the sun and the heated interior of the earth. if the former melted condition of the entire mass of the earth be assumed, the temperature of the surface must have been increased, by conduction of heat from within, for long periods after the superficial stratum had become solid. it is, however, susceptible of proof, that the present climates are not sensibly affected by interior heat, though at a little more than a mile below the surface the temperature is equal to that of boiling water. at any time, therefore, after the waters had become condensed, collected into oceans, and become sufficiently cool to support the animal life of which the remains are now found, it is not probable that the climate was, to any considerable extent, influenced by the heat conducted from the interior. still, there have been great changes of climate since those early organic forms existed; and, since we have no ground for supposing that the temperature of the sun's rays has suffered any reduction, we have to inquire whether the means of retaining the heat from the sun could at any time have been different. _the relative position of land and water_ depends, as we have seen, upon igneous causes, and has been very different at different times. we shall find that climate must have been greatly modified by these changes; for the land radiates and absorbs heat freely, and water possesses this power in a very low degree. let us suppose the zone comprised between the tropics to be occupied by land, and the portions without these limits to be covered with water. under these conditions, the land, having a nearly vertical sun the whole time, would accumulate heat to a degree scarcely compatible with the existence of animal life. this is sufficiently proved by the oppressive tropical climates of the present time, influenced as they are by polar lands and contiguous seas. under the same conditions, the sea would be heated by contact with the land, and the heat would be distributed by marine currents to the polar regions. but the water thus distributed would not part with its heat, because it has but little radiating power, and nowhere comes in contact with polar land. it follows, then, that both land and water would be subjected to a very high temperature. but, if we suppose the land confined to the polar regions, and the sea to the equatorial, the opposite results would follow. the equatorial sea would absorb but a small proportion of the solar heat which would be thrown upon it. the land would receive the sun's rays too obliquely to receive much elevation of temperature, as the present polar climates show. hence, the temperature of the earth would differ but little from that of the planetary spaces, which is fifty-eight degrees below zero, a temperature too low to allow of any considerable development of organic life. these are the conclusions to which we are led by considering the different powers of land and water to absorb and radiate heat, and we shall find that the existing climates are in accordance with these conclusions. america has a lower temperature than europe in the same latitudes. it has also a smaller proportion of land in the equatorial regions, and a greater proportion in the north polar regions. the eastern continent is colder in asia than in europe in the same latitudes. it has also less equatorial and more polar land. the southern is colder than the northern hemisphere at equal distances from the equator. there is also less land near the equator on the south side, and probably as much land around the south as the north pole. hence, we see that there may have been such a relation of land and water as to account for all the variations of temperature which are known to have existed. we cannot say that such actually has been the case. we can tell, with some degree of accuracy, what portions of the present continents were land at the several geological periods; but three-fourths of the surface of the earth is covered with water, and of the condition of this portion during those periods we have no means even of conjecturing. we can only say, that, by the operation of known causes, the relative position of land and water may have been such as to produce the climates known to have existed at former periods of the history of the earth. index. page a. abundance of vegetable products of the coal period, accumulation of vegetable matter, actinolite, action of internal heat, action of waves, in forming harbors, advantages of geological changes, Ætna, , agate, age of rocks, doubtful-- from change of lithological character, from distance, from disturbance, alternation of coarse and fine material, aluminium, amethyst, amygdaloidal structure, ancient volcanic rocks, andes, granite veins in, angle of inclination, anoplotherium, anticlinal axis, aqueous causes, aqueo-glacial action, argillaceous schist, , arrangement of materials in the crust of the earth, artesian wells, asbestos, atmospheric causes, atolls, augite, auvergne, volcanic district of, b. basalt, bed of the sea-- sunken areas in the, why elevated, belemnites, breccia, brine springs-- in silurian rocks, in the carboniferous formation, in the new red sandstone, c. calamite, calcium, cambrian system, carbon, carbonate of lime, carbonate of magnesia, carbonic acid a cause of disintegration of rocks, carboniferous formation, essential to national wealth, extent of, a prospective arrangement, faults in, not always disturbed by faults, carboniferous limestone, sometimes becomes a coal-bearing rock, fossils of the, carnelian, cause of internal heat, cause of stratification, caverns, cephalaspis, cephalopoda, in oölite, chalcedony, chalk, changes of climate, how produced, changes in the crust of the earth, of temperature a disintegrating agent, at the surface, chemical action, in solids, in crystallization, chlorine, chlorite, chlorite slate, classification of rocks, clay, clay slate, cleavage structure, , coal, varieties of, mode of quarrying, origin of, conversion of vegetable matter into, now forming, coal measures, fossils of the, coal plants, tropical character of, coal and iron associated, clouded marble, columnar structure, , compact limestone, concretionary formations, conglomerate, of old red sandstone, connecticut valley-- one of denudation, trap of, continents-- mean elevation of, total elevation of, elevated gradually, why depressed, contorted strata, coral formation, , extent of, coral reefs-- fringing, barrier, coral rag, corals in silurian rocks, copper mines of lake superior, creation, a progressive work, cretaceous formation, cretaceous formation, fossils of, geographical range of, crinoidea in silurian rocks, crust of the earth, expansion and contraction of, d. delta deposits, denudation of igneous rocks, denudation of sedimentary rocks, denudation produced by earthquake waves, deposition of sediment, diluvium, dike, , divisional planes, , dolomite, , drift, extent of, connected with striated surface of the rocks, connected with subsidence, , e. earth in a state of change, earthquakes, wave-like motion of, earthquake waves, rocks shivered by, effect of atmospheric agencies, electrical discharges, effect of, elementary substances, elevation and subsidence, elevation and subsidence several times repeated, elevation of mountains, cause of, spasmodic, gradual, elevation of different mountains at different times, elevation of continents, cause of, elevation of north america, elevation of the coast of maine, elevation of europe, elevation of south america, encrinites, , f. fault, , felspar, filling up of lakes, fingal's cave, fissile structure, origin of, flint, in chalk, , fluorine, folded axes, , formation of soils, fossils-- definition of, how preserved, mineralization of, use of, order in which animals appeared, shown by, animal and vegetable, created together, as a record of climate, , fossiliferous rocks, classification of, fractures, , , opening downward, g. garnet, geological causes, how far uniform, geological causes, slow operation of, geological investigations aided by displacement of strata, geological periods, prolonged, shown by amount of strata, shown by duration of species, shown by amount of organic matter, shown by microscopic accumulations, geology and revelation, giant's causeway, glacial period, glacial theory, glaciers-- how formed, cause of motion, when they decrease, earthy matter on them, lateral moraines, surfaces grooved by, terminal moraines, gneiss, , gorge, graham island, granite, varieties of, thickness of, structure of, formation of, igneous origin of, granite veins, in granite, granite of different ages, granitic axes of mountains, , greensand, , greenstone, , grooved surfaces of rock, , , gypsum, in new red sandstone, beds, how produced, h. hall, sir james, experiments, , heterocercal tails of fishes, homocercal tails, hornblende, hornblende slate, , hydrogen, hypersthene, hypersthene rock, , i. icebergs-- how formed, earthy materials in, motion of, size and number of, effect in distributing drift, grooving the surface, iceland spar, iceland, volcanic eruption in, ichthyosaurus, igneous causes, iguanodon, inclined position of strata produced by upheaval, , increase of temperature below the surface, iron, j. jasper, jorullo, k. kilauea, , l. lakes, filling up of, , lava, , , varieties of, tertiary, elastic vapors contained in, , great quantity of modern, lead-bearing strata, , lepidodendron, lias, , limestone, , as a primary rock, metalliferous, local changes of climate, m. magnesian limestone, , magnesium, mammoth, man-- recently created, as an agent in producing geological changes, impressions of the feet of, skeleton of from guadaloupe, manganese, marine currents, marine currents, cause of, abrading power of, marl, mastodon, megatherium, metamorphic changes, metamorphic rocks, amount of, origin of, order of superposition, upper limit variable, localities of, metallic ores, mica, slate, , millstone grit, fossils of, becomes coal measures, mineral-- definition of, mineral veins, formation of, modern formation, why but little known, fossils, moisture of the atmosphere a disintegrating agent, monte nuovo, mount loa, eruption of, n. neocomian system, new red sandstone, fossils of, ores of, geographical range of, niagara falls, how preserved, nitrogen, nummulite rock, o. oceanic mountains, ocean level, nearly permanent, old red sandstone, fossils of, extent of, oölite, oölitic structure, oölite system, calcareous, fossils of, localities of, opal, organic causes, orthoceras, , outcrop, oxide of iron, oxygen, p. paleotherium, papandayang, , permian system, plesiosaurus, porphyritic structure, potassium, primary limestone, pterodactyle, pumice-stone, pyroxene, q. quartz, rock, r. raindrops, impressions of, raised beaches, ravine, recent elevation in europe, recent formation, ripple marks, rivers-- beds of, raised, continued into the sea, abrading action of, abrading action of promoted by foreign substances, rock crystal, rock salt, , rocks, denned, rose quartz, s. saccharine limestone, , saliferous system, saline properties of the ocean, how obtained, salt beds-- where found, how formed, sandstone, schorl, scoriæ, , sediment-- amount of in rivers, deposition of, sorted by rivers, selenite, serpentine, a primary rock, shale, siberia, remains of elephants in, sigillaria, silicium, sinking of wharves, towns, &c., silurian system, tabular arrangement of, divisions of, fossils of, geographical range, slaty structure-- in the gold washings of chili, produced by electric currents, slope of mountains, soapstone, sodium, solidification of rocks, , soluble materials of rocks, solution of mineral substances-- promoted by heat, promoted by an alkali, promoted by carbonic acid, sources of the sedimentary materials, sources of the sediment of rivers, species-- disappearance of, causes of the disappearance of, springs, stability of continents only apparent, statuary marble, stigmaria, strata-- horizontal, , permeable and impermeable, irregular, how produced, striated surfaces, submerged forests, subsidence of land, , subsidence of land in greenland, subsidence and elevation in the pacific, sulphate of lime, sulphur, sun-cracks, sunken areas, syenite, synclinal axes, t. taconic system, talc, talcose slate, , temperature at great depths, temple of jupiter serapis, tertiary system, age, how determined, fossils, divisions of, geographical range, tilestones of the old red sandstone, trachyte, tracks in new red sandstone, transportation of sediment, trappean rocks, localities of, tremolite, trias, trilobite, , v. valley, of elevation, , of subsidence, valley of denudation, vein of segregation, verd-antique marble, volcanic rocks, , of different ages, in what states ejected, volcanic mountains, dimensions, volcanic activity-- regions of, water essential to, volcanic cones-- formation of, lateral, volcanic cinders, scoriæ, glass, volcanic action, effects of, volcanic origin-- of trappean rocks, of granitic rocks, volcanoes-- number, linear arrangement of, near the sea, new, of the tertiary period, long active, w. watt on fusion of basalt, waves, action of, wealden, wind a geological agent, z. zechstein, questions to elements of geology questions. chapter i. section i. how many elementary substances are known? in what combinations is oxygen found? what proportion of the earth's crust consists of it? in what combinations does hydrogen occur? nitrogen? carbon? sulphur? chlorine? fluorine? iron? manganese? how does silicium occur? aluminium? potassium? sodium? calcium? magnesium? how are these elementary substances classified? (silicium, or silicon, has but a doubtful claim to be regarded as metallic.) section ii. what is a simple mineral? how many are known? what are the physical properties of quartz? how are the several varieties distinguished? what are the physical properties of felspar? mica? hornblende? how are its varieties distinguished? augite? hypersthene? talc? how are its varieties distinguished? serpentine? carbonate of lime? gypsum? its varieties? what other minerals are mentioned? section iii. define the crust of the earth. rocks. what are the unstratified rocks? what is the structure of granite? how are the varieties distinguished? what is the porphyritic structure? describe hypersthene rock. what are volcanic rocks? lava? scoriæ? pumice-stone? how is the vesicular structure produced? what are volcanic breccias? volcanic grits? what is the composition of the trappean rocks? what is the amygdaloidal structure? what are the three varieties of trappean rocks, and how are they distinguished? [illustration: fig. .] name the stratified rocks. describe gneiss. mica slate. sandstone. conglomerate. greensand. describe the varieties of limestone. what is dolomite? of what does clay consist? clay slate? what modifications does clay slate present? what is diluvium? chapter ii. section i. what is the primary division of rocks? upon what principle are the unstratified rocks divided? upon what principle are the stratified rocks divided? why are the non-fossiliferous called metamorphic rocks? name the four classes of rocks. section ii. what is the most abundant plutonic rock? how is its thickness ascertained? what is its amount? where is it found? what is its ordinary structure? what peculiarity of structure facilitates the cleavage of granite? [illustration: fig. .] the granitic masses are generally deep below the surface; in what other position does granite appear? [illustration: fig. .] [illustration: fig. .] in what classes of rocks are granite veins found? were they all produced at the same time? how is this demonstrated? what is the relative position of the older and newer granites? what other plutonic rocks occur in considerable quantities? section iii. of what do volcanic rocks consist? in what states are they ejected? what are the principal varieties of lava, and how are they distinguished? why is the basaltic lava the last to be ejected? how is the age of the volcanic rocks determined? what are the three divisions of the volcanic rocks, as dependent upon age? what is the proportion of the volcanic to other rocks? how many active volcanoes exist? describe the eruptions of kilauea. describe the eruption in iceland in . what are the dimensions of mount Ætna, and how has it been produced? how are the tertiary lavas known to be such? where have they been most studied? what is the evidence that these rocks in france are volcanic? have these lavas been produced within the historic period? [illustration: fig. .] were they produced at an early period in the earth's history? give the evidence that their activity was long-continued. [illustration: fig. .] what is the form of the earlier volcanic rocks? what circumstances distinguish the trappean from other volcanic rocks? what are some of the prominent localities of the trappean rocks? how do they occur in the islands west of scotland? how in the valley of the connecticut river? section iv. what is the lowest metamorphic rock? describe it. how does mica slate differ from gneiss? is it well distinguished from argillaceous slate? what is the third rock in the metamorphic series? why is it difficult to determine the upper limit of this series? why do the principal rocks of this series occur in the order here given? what other rocks may take the place of these principal rocks? where do the metamorphic rocks occur? what is their thickness and amount? section v. how many systems of fossiliferous rocks are there, and what are they? what other system is provisionally introduced? what is its position? [illustration: fig. .] describe it. what materials of value are obtained from this system? [illustration: fig. .] what fossils does it contain? in what localities is it found? what explanation, in reference to these rocks, is given by those who deny that they constitute a distinct system? [illustration: fig. .] [illustration: fig. .] in what respects does the state of new york present the best facilities for studying the silurian system? describe the champlain division. [illustration: fig. .] the ontario division. the helderberg division. [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] describe the erie division. what are the fossils of this system? [illustration: fig. .] describe the crinoidea. the cephalopoda, and the two forms. [illustration: fig. .] the trilobite. what higher forms of animal life existed during the silurian period? the geographical range of the system? of what does the old red sandstone consist? describe its three divisions. what are its fossils? [illustration: fig. .] describe the fishes of that period. what was the peculiarity of the pterichthys? of the cephalaspis? where are the rocks of this system found? how is the carboniferous system divided? describe the carboniferous limestone. what ores are found in it? describe, its fossils. describe the millstone grit. of what do the coal measures consist? how does the ironstone occur? describe the coal beds. how is the continuity of the strata interrupted? what variations from this general type occur in the formation? [illustration: fig. .] [illustration: fig. .] describe the several varieties of coal. how is the coal quarried? [illustration: fig. .] what mineral springs occur in this formation? to what uses is coal applied? (the coal was deposited thousands of years ago, and has served no useful purpose, that we know of, till very recently. its formation was planned and completed to meet a want which was not to be felt till the lapse of many ages. it is a notable instance of the wisdom and forethought, as well as of the benevolence, of god.) in what does this prospective arrangement consist? what are the character and position of the fossils of the coal measures? [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] what are the four most abundant forms? describe the stigmaria. the sigillaria. the lepidodendron. the calamite. where are the beds of coal found? what is the fourth formation of rocks? into what two portions is it divided? of what does the permian portion consist? the trias? what minerals are found in this formation? what springs? [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] what fossils? how are the fishes of the earlier and later portions distinguished? what peculiarity of the red sandstones is mentioned? by what kinds of animals were the tracks, which they contain, made? give localities of the new red sandstone. what are the three divisions of the oölitic system? [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] describe the lias. the oölite. the wealden. what are the general peculiarities of the system? [illustration: fig. .] what are the fossil animals of the system? by which class of fossil animals is the system characterized? [illustration: fig. .] describe the ichthyosaurus. the plesiosaurus. pterodactyle. the iguanodon. where is the system developed? what are the divisions of the cretaceous system? how are the layers of chalk separated? what is the geological position of the neocomian system, and the greensand of this country? what are the fossils of this system? [illustration: fig. .] [illustration: fig. .] what the geographical range? how are the tertiary deposits distinguished from the older formations? upon what principle is the tertiary system divided? what are these divisions called, and what does each, name signify? [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] in what portion of the tertiary period was the drift deposited what is the geographical range of the drift? of what does it consist? what is the latest tertiary deposit? what are the fossils of the tertiary system? describe the paleotherium. the anoplotherium. the megatherium. the mastodon. the mammoth. what other animals belonged to this period? where are the tertiary deposits found? what formations are regarded as recent? what formations of this class are accessible? what others are in progress? what are the fossils of this formation? section vi. what is a fossil? in what ways are they preserved? when is a fossil said to be mineralized? describe the process of mineralization. how is it proved that the removal of the organic matter and substitution of mineral particles are simultaneous? were animals created before vegetables? how is this shown? at what period was the vegetable growth the greatest? what forms of animal life were most abundant during the earlier periods? what vertebrated animals belonged to these periods? what advance is made in the new red sandstone period? during what period do the mammalia first appear in abundance? during what geological period was man created? how are the footprints and skeletons of human beings hi solid rocks accounted for? why are not fossils distributed uniformly through all the formations, and through all the parts of each formation? in what does the importance of fossils consist? how are the fresh-water and marine formations distinguished? what circumstances render it difficult to identify rocks of the same age in different localities? how are formations identified? was the work of creation one of short duration? what was the last work of creation of which we have any geological evidence? why may we presume that no more species will be created? do all the animal and vegetable species which have been created still exist? [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] what causes are operating to destroy species? section vii. how long has it been since the creation of the earth? how does the amount of stratified rock indicate the great antiquity of the earth? how does the stratification show the same thing? what is the proof that the principal strata were deposited before the creation of man, and how does this fact bear upon the question of the antiquity of the earth? give the argument drawn from the successive creations and disappearance of animal and vegetable species. the argument drawn from the amount of organic matter in the stratified rocks. the argument from slow accumulation. what is the general conclusion from these facts? why is this conclusion an important one? what objection to it has been raised? how is this objection answered? what additional explanation is given? chapter iii. section i. what is the deepest geological change of which we have any knowledge? what are the reasons for supposing that the lowest stratified rocks are undergoing fusion? why are the lowest stratified rocks regarded as of mechanical origin? what changes have they undergone? section ii. in what state were the stratified rocks deposited? what change have they undergone in this respect? how is the fissile structure produced? how is the cleavage structure produced? [illustration: fig. .] what is the third class of changes? what do fractures at the surface become by the erosion of water? how are caverns formed? describe a vein of segregation. a dike. a mineral vein. what is a fault? were the inclined strata thus deposited? how is it proved that they have taken the inclined position since they were deposited? what is the direction of the dip? what lines form the angle of inclination? what is the outcrop of inclined strata? the strike? [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] describe an anticlinal axis. a synclinal axis. a valley of elevation. a valley of subsidence. [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] when are strata unconformable? what other disturbances have taken place in the strata? when did these various disturbances take place? how is it known that there has been no period of universal disturbance? section iii. how is it known that the mountains have been covered by the ocean? [illustration: fig. .] [illustration: fig. .] were the granitic ridges thus covered? has the level of the sea been, to any considerable extent, fluctuating? how, then, have the rocks, of which the mountain masses consist, been covered by sea? give the evidence that different mountains were elevated at different times. has the process of upheaval been sudden or gradual? how are the mountain valleys, which have the direction of the mountain ranges, been produced? [illustration: fig. .] how is the existence of submarine mountains shown? what is the movement by which continents are elevated? state the evidence of the elevation of continents from the existence of elevated sea-beaches. the evidence of the elevation of the coast of maine. the evidence of elevation from the existence of lakes. from the geographical range of the older strata. the evidence of the recent elevation of south america. of the rising of the north of europe. state the proof of subsidence from the occurrence of submerged forests. why are these changes but little observed? [illustration: fig. .] what are the grounds for asserting that a change of level is taking place over a large area in the pacific and indian oceans? [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] [illustration: fig. .] what is the present state of the coast of greenland in this respect? have the changes of level of the same place always been in the same direction? give the evidence of elevation and depression in south america. in italy. [illustration: fig. .] what general conclusion may we draw in respect to the stability of the earth's surface? to what extent can we ascertain the geography of past epochs? what former relations of land and water are suggested as not improbable? section iv. how can we estimate the denudation which the igneous rocks have suffered? how do faults indicate the denudation of the stratified rocks? how do valleys indicate denudations? describe the instance in scotland. what is the evidence of denudation in the connecticut valley? how are valleys produced? [illustration: fig. .] what is the condition of the surface rock in the colder portions of the temperate zones? [illustration: fig. .] [illustration: fig. .] with what is the surface rock generally covered? how are soils formed? how may soils be improved? what is necessary to render soils fertile? section v. what means have we of judging of the climate of former periods? what was the climate of the coal period? what animal fossils indicate a former warm climate? what evidence that siberia once enjoyed a milder climate? do similar indications appear in the southern hemisphere? when has the climate of the earth been most uniform? has the climate been growing gradually colder to the present time? what is the evidence of a somewhat recent period of intense cold? what recent local changes of climate are mentioned as having occurred? section vi. state the general advantages of geological changes. by what changes have the coal-beds and other stratified rocks become accessible? what advantage from these elevating forces in reference to the granitic rocks? [illustration: fig. .] how do these changes affect our means of knowing the structure of the earth? explain the origin of springs, wells, and artesian wells? by what changes have the metallic ores become accessible? in what light, then, are we to regard disturbances of geological structure? chapter iv. what is the object of the preceding chapters? how can we arrive at a knowledge of the causes which have produced geological phenomena? have geological causes always operated with the same intensity? how are the means of forming correct geological theories increasing? section i. how does oxygen become an agent in the disintegration of rocks? how does carbonic acid operate in the disintegration of rocks? what is the effect of moisture and rain? what is the effect of variations of temperature? what other atmospheric causes are mentioned? how do these causes become important? what are some of their effects? section ii. what are the changes which are to be referred to chemical agency? mention some of the disturbances which give rise to chemical changes. what are the principal effects of chemical action? how is the cleavage structure accounted for? [illustration: fig. .] [illustration: fig. .] mention instances which show that a cleavage may be established in a body in a solid state. in it a crystalline arrangement of the particles of the mass? what other divisional planes exist in rocks? mention instances of concretionary formations. why may not these concretions have been deposited as nodules? how have these concretions been formed? mention instances of segregation without the concretionary structure. how was the segregation in these instances effected? how is the columnar structure produced? what is the origin of the mineral veins which are first mentioned? how is it shown that other veins are not injected? how were these veins formed? what is the force by which these molecular changes have been effected? section iii. in what ways are geological changes produced by human agency? of what are the organic remains, in rocks, the record? what rocks contain organic materials in large quantity? what is the most abundant organic product? explain the mode of growth of corals. give instances of extensive coral reefs. what is the total amount of surface covered by the coral reefs? section iv. what degree of importance is attached to water as a geological agent? what are the sources of the sediment which water deposits? why is not the formation of the sedimentary rocks capable of being observed? what is the first mode in which solid matter is taken up by water? why are the waters of the ocean saline? what effect has the temperature of water in the solution of silex? what effect has an alkaline condition of water? [illustration: fig. .] what rock is soluble in water charged with carbonic acid? give an instance of limestone formation from such solutions. how do rivers furnish sediment for the stratified rocks? what determines the position of rapids in rivers? what is the effect of waterfalls on the abrading action of rivers? what is the peculiarity of rock at niagara which has prevented the fall from becoming a succession of rapids? what other circumstance increases the abrading action of rivers? what is the principal source of the sediment which is transported by rivers? what is the annual amount of sediment furnished by the kennebec? the merrimac? the mississippi? the ganges? what is the general tendency of these abrading forces? what is the effect of waves upon the coast, when it consists of unsolidified materials? describe their effect upon rocky coasts. how is the encroachment upon such coasts shown? [illustration: fig. .] what is the effect of waves of less power? how are marine currents produced? how are they increased by the evaporation of the torrid zone? what are the most important marine currents? which class of currents have the greater depth? upon what does the power of deep currents depend? how would the effect of these currents be increased by earthquakes? where will the effects of these currents be greatest? mention instances of these effects. [illustration: fig. .] what must be the effect of such currents as the gulf-stream and mozambique channel? mention, generally, the effects of these currents. why does detrital matter remain suspended in the water of rivers? how is the coarse and fine sediment separated? why do river currents extend some distance into the sea? what effect does this have in distributing the sediment which the rivers furnish? upon what does the transporting power of marine currents depend? when a river enters a lake, why is its sediment deposited? describe the effect. when is sediment deposited in the beds of rivers? describe the effects of this deposition. where is most of the sediment deposited? give the area of some delta deposits. how do the deep-sea deposits now forming compare in extent with the earlier formations? state the several circumstances by which a succession of deposits would be arranged in strata. how are those differences produced upon which the separation into independent formations depends? why are marine deposits nearly horizontal? [illustration: fig. .] how are the irregular stratifications produced? what peculiarity in the fossils will distinguish the lacustrine and marine deposits? what peculiarity in reference to fossils will characterize the deep-sea deposits? how is coal shown to be of vegetable origin? why will the drift wood of the sea accumulate in particular localities, and why will it sink? why will it become buried beneath earthy matter? how is it known that wood thus buried will, at length, become lignite? how is lignite converted into mineral coal? what is the proof of it? have beds of coal been formed at other periods, besides the carboniferous? is it probable that coal-beds are now forming? how did the flora of the carboniferous period differ from the existing flora? [illustration: fig. .] are the alternations of the earthy and coal strata satisfactorily explained? in what portions of the geological series are the deposits of salt found? where is saline matter principally stored? explain the conjectural formation of salt in the mediterranean sea. what form do rocks take when deposited from a chemical solution? how is sand or gravel solidified by the infiltration of mineral waters? what is the effect of drying upon the solidification of rocks? what is the effect of pressure? what of heat? section v. what is a glacier? what is the extent of the glaciers of the alps? what change does the mass of snow in the higher valleys of the glacier mountains undergo? what is the source of supply to the glacier? what is the cause of the motion of the glacier? what is the usual annual motion? why will the glacier melt but little at its under side? where will the waste at the surface just equal the addition? what circumstances vary the position of the terminus of the glacier? [illustration: fig. .] what, besides snow and ice, enters into the composition of a glacier? how are these materials supplied? how is a lateral moraine formed? what effect has the motion of the glacier on the rocky surface over which it passes? what is the material by which this effect is produced? how is the terminal moraine produced? how may the moraines on the jura mountains be explained? how has it been proposed to explain the striated surfaces of rocks found in the north of europe and america? what is the objection to this extension of the glacier theory? how does the ice accumulate along the coast in high latitudes to form icebergs? why does it ultimately separate from the shore? how does it become freighted with earthy matter? in what direction do the icebergs float, and why? what are the dimensions of an iceberg, estimated from the part that is visible? [illustration: fig. .] where does the mass of ice increase, and where diminish? what will be the effect of its melting? how is it supposed that icebergs may have striated the rocky surface? what is probably the condition of the bed of the seas over which icebergs now float? has the north of europe and america been so depressed, during a period comparatively recent, as to admit of this explanation of the drift phenomena? section vi. what is the condition of the interior of the earth with respect to heat? how do the observations made in deep mines and wells prove this? how far is the temperature influenced from the surface? what is the general law of increment of temperature? at what depth would most mineral substances be melted? how is this conclusion confirmed? what was probably the original state of the mass of the earth? what other explanation may be given of this interior heat? what is the elastic force upon which volcanic phenomena depend? upon what does the fluidity of lava depend? upon what does its porous structure, when cooled, depend? why are volcanoes situated near the sea? describe the principal lines of volcanic activity. what are the forces tending to repress the elasticity of the mass below? what will be the effect when the elastic is greater than the repressing force? what produces the phenomena of the earthquake? what is a volcano? why are volcanoes generally arranged a linear direction? under what circumstances will a new volcano be formed? what instances are cited? how is a volcanic cone formed? why are lateral cones produced? how are volcanic cinders formed? scoriæ? volcanic glass? [illustration: fig. .] give instances of fractures as results of volcanic action. how are dikes formed? [illustration: fig. .] by what agency have the changes in the metamorphic rocks been effected? give the instance of metamorphic action from intrusive granite in norway. what instance is given as occurring in new hampshire? give the experiment by which it is shown that these changes will result from a high temperature. [illustration: fig. .] what must be the condition of the lowest stratified rocks in regard to temperature? why is not the stratification destroyed? what changes are produced by this high temperature? explain the connection of denudation and earthquake action. what is the evidence that the surface of the earth is thrown into undulations during earthquakes? what is the velocity of these undulations? give the instance which occurred in chili. to what parts of the earth are these undulations limited? what condition of the surface may be regarded as resulting from this cause? what is the class of rocks most obviously referable to volcanic agency? how do the trap rocks differ from ordinary lavas? why are they not vesicular? why more crystalline? why were cones never formed? what is the proof that the granitic rocks have once been in a melted state? why does not the mass of melted rock below the surface retain permanently its liquid form? why does it, on cooling, become more crystalline than lava? state the process by which mountains are formed. by what law does the elevating force accumulate? why, then, is the process of elevation spasmodic, and not constant? how is the inclined position of strata produced? how are strata brought into a vertical position over large areas? why do subsidences occasionally follow these movements of elevation? mention instances. [illustration: fig. .] what explanation is suggested of deep and extensive chasms? what conditions must exist together, in the force by which continents are produced? what cause fulfils these conditions? what is the proof that the temperature under given localities is variable? what will be the result of these variations? what is the law of expansion of rocks, as obtained by experiment? what amount of change of level may be thus accounted for? what circumstances would probably increase this amount? what amount of vertical movement must be accounted for? why must these changes of level be very slow? under what conditions would there be no change of level? is it probable that these conditions exist to any great extent? why, then, are not the changes of level observed? why is the bed of the sea most likely to experience the change of elevation? why are the continents most favorably situated to undergo depression? what are the sources of heat upon which climate depends? does the interior temperature sensibly affect the present climates? what cause may be assigned for the changes of climate which are known to have taken place? what are the relations of land by which the highest temperature would be produced? how would this distribution of land affect the temperature of the waters of the ocean? what would result if the opposite relations of land and water existed? what confirmation of these conclusions is drawn from the existing climates of different parts of the earth? is there any reason to suppose that the relations of land and water which would have produced a warmer climate in former times did not exist? obtained from the internet archive. the story of the earth and man. by j. w. dawson diagram of the earth's history. -------------------------------------------------------- animals rock formations plants -------------------------------------------------------- age n modern age of e t post-pliocene of man o i pliocene angiosperms (upper z m pliocene and strata) o e miocene plants and i eocene mammals c -------------------------------------------------------- m age e cretaceous age s t of of o i jurassic cycads z m and reptiles o e triassic pines i c -------------------------------------------------------- permian age of age of p amphibians a carboniferous acrogens and fishes l t Æ i erian or and ------ o m z e devonian gymnosperms age of o mollusks i silurian ------ corals c and siluro- age crustaceans cambrian of cambrian algæ huronian? ------------------------------------------------------ age of e laurentian plants protozoa o t z i not o m i e determinable c harper & brothers new york. the story of the earth and man, by j. w. dawson, ll.d., f.k.s., f.g.s., principal and vice-chancellor of mcgill university, montreal, author of "archaia," "acadian geology," etc. new york: harper & brothers, publishers, franklin square preface the science of the earth as illustrated by geological research, is one of the noblest outgrowths of our modern intellectual life. constituting the sum of all the natural sciences in their application to the history of our world, it affords a very wide and varied scope for mental activity, and deals with some of the grandest problems of space and time and of organic existence. it invites us to be present at the origin of things, and to enter into the very workshop of the creator. it has, besides, most important and intimate connection with the industrial arts and with the material resources at the disposal of man. its educational value, as a means of cultivating the powers of observing and reasoning, and of accustoming the mind to deal with large and intricate questions, can scarcely be overrated. but fully to serve these high ends, the study of geology must be based on a thorough knowledge of the subjects which constitute its elementary data. it must be divested as far as possible of merely local colouring, and of the prejudices of specialists. it must be emancipated from the control of the bald metaphysical speculations so rife in our time, and above all it must be delivered from that materialistic infidelity, which, by robbing nature of the spiritual element, and of its presiding divinity, makes science dry, barren, and repulsive, diminishes its educational value, and even renders it less efficient for purposes of practical research. that the want of these preliminary conditions mars much of the popular science of our day is too evident; and i confess that the wish to attempt something better, and thereby to revive the interest in geological study, to attract attention to its educational value, and to remove the misapprehensions which exist in some quarters respecting it, were principal reasons which induced me to undertake the series of papers for the _leisure hour_, which are reproduced, with some amendments and extension, in the present work. how far i have succeeded, i must leave to the intelligent and, i trust, indulgent reader to decide. in any case i have presented this many-sided subject in the aspect in which it appears to a geologist whose studies have led him to compare with each other the two great continental areas which are the classic ground of the science, and who retains his faith in those unseen realities of which the history of the earth itself is but one of the shadows projected on the field of time. to geologists who may glance at the following pages, i would say that, amidst much that is familiar, they will find here and there some facts which may be new to them, as well as some original suggestions and conclusions as to the relations of things, which though stated in familiar terms, i have not advanced without due consideration of a wide range of facts, to the general reader i have endeavoured to present the more important results of geological investigation divested of technical difficulties, yet with a careful regard to accuracy of statement, and in such a manner as to invite to the farther and more precise study of the subject in nature, and in works which enter into technical details. i have endeavoured as far as possible to mention the authors of important discoveries; but it is impossible in a work of this kind to quote authority for every statement, while the omission of much important matter relating to the topics discussed is also unavoidable. shortcomings in these respects must be remedied by the reader himself, with the aid of systematic text-books. those who may desire any farther explanation of the occasional allusions to the record of creation in genesis, will find this in my previously published volume entitled "archaia." j. w. d, mcgill college, montreal, _january, _. contents. page chapter i.--the genesis of the earth. uniformity and progress.--internal heat.--nebular theory.--probable condition of the primitive world chapter ii.--the eozoic ages. the laurentian rocks.--their character and distribution.--the conditions of their deposition.--their metamorphism.--eozoon canadense.--laurentian vegetation chapter iii.--the primordial or cambrian age. connection of the laurentian and primordial.--animals of the primordial seas.--lingula, trilobites, oldhamia, etc.--the terms cambrian and silurian.--statistics of primordial life chapter iv.--the silurian ages. geography of the continental plateaus.--life of the silurian.--reign of invertebrates.--corals, crinoids, mollusks, crustaceans.--the first vertebrates. silurian fishes.--land plants chapter v.--the devonian or erian age. physical character of the age.--difference of deposits in marginal and continental areas.--specialisation of physical geography.--corals, crustaceans, fishes, insects, plants chapter vi.--the carboniferous age. perfection of palæozoic life.--carboniferous geography.--colours of sediments.--vegetation.--origin of coal.--land life.--reptiles, land snails, millipedes, etc.--oceanic life chapter vii.--the permian age. movements of the land.--plication of the crust.--chemical conditions of dolomite, etc.--geographical results of permian movements.--life of the period. summary of palæozoic history chapter viii.--the mesozoic ages. characters of the trias.--summary of changes in the triassic and cretaceous periods.--changes of the continental plateaus.--relative duration of the palæozoic and mesozoic.--mesozoic forests.--land animals.--the reign of reptiles.--early mammals and birds chapter ix.--the mesozoic ages (continued). animals of the sea.--great sea lizards, fishes, cephalopods, etc.--chalk and its history.--tabular view of the mesozoic ages chapter x.--the neozoic ages. physical changes at the end of mesozoic.--subdivisions of the neozoic.--great eocene seas.--land animals and plants. life of the miocene.--reign of mammals chapter xi.--the neozoic ages (_continued_). later vegetation.--the animals of the pliocene period. approach of the glacial period.--character of the post-pliocene or glacial chapter xii.--close of the post-pliocene, and advent or man. connection of geological and human history.--the post-glacial period.--its relations to the pre-historic human period.--elevation of post-pliocene land.--introduction of man.--subsidence and re-elevation.--calculations as to time.--tabular view of the neozoic ages chapter xiii.--advent of man (_continued_). relations of post-pliocene and modern animals.--cavern deposits.--kent's cave.--general remarks. chapter xiv.--primitive man. theory of evolution as applied to man.--its demands.--its deficiencies.--fallacious character of arguments of derivationists. hypothesis of creation.--its demands and advantages chapter xv.--primitive man (_continued_). geological conditions of man's introduction.--his modern date.--his isolated position.--his higher powers.--pictures of primitive man according to evolution and creation.--general conclusion list of illustrations. page ideal sections illustrating the genesis or the earth america in the laurentian period eozoon canadense life in the primordial age organic limestone of the silurian life in the silurian life in the devonian vegetation of the devonian carboniferous plants oldest land snails carboniferous reptiles foldings of the crust in the permian period curves of elevation and depression culmination of types of palæozoic animals land animals of the mesozoic aquatic animals of the mesozoic foraminiferal rock-builders miocene mammals britain in the post-pliocene the story of the earth and man. chapter i. the genesis of the earth. the title of this work is intended to indicate precisely its nature. it consists of rough, broad sketches of the aspects of successive stages in the earth's history, as disclosed by geology, and as they present themselves to observers at the present time. the last qualification is absolutely necessary, when dealing with a science whose goal to-day will be its starting point to-morrow, and in whose view every geological picture must have its light and shaded portions, its clear foreground and its dim distance, varying according to the lights cast on them by the progress of investigation, and according to the standpoint of the observer. in such pictures results only can be given, not the processes by which they have been obtained; and with all possible gradations of light and distance, it may be that the artist will bring into too distinct outline facts still only dimly perceived, or will give too little prominence to others which, should appear in bold relief. he must in this judge for himself; and if the writer's impressions do not precisely correspond with those of others, he trusts that they will allow something for difference of vision and point of view. the difficulty above referred to perhaps rises to its maximum in the present chapter. for how can any one paint chaos, or give form and filling to the formless void? perhaps no word-picture of this period of the first phase of mundane history can ever equal the two negative touches of the inspired penman--"without form and void"--a world destitute of all its present order, and destitute of all that gives it life and animation. this it was, and not a complete and finished earth, that sprang at first from its creator's hand; and we must inquire in this first chapter what information science gives as to any such condition of the earth. in the first place, the geological history of the earth plainly intimates a beginning, by utterly negativing the idea that "all things continue as they were from the creation of the world." it traces back to their origin not only the animals and plants which at present live, but also their predecessors, through successive dynasties emerging in long procession from the depths of a primitive antiquity. not only so; it assigns to their relative ages all the rocks of the earth's crust, and all the plains and mountains built up of them. thus, as we go back in geological time, we leave behind us, one by one, all the things with which we are familiar, and the inevitable conclusion gains on us that we must be approaching a beginning, though this may be veiled from us in clouds and thick darkness. how is it, then, that there are "uniformitarians" in geology, and that it has been said that our science shows no traces of a beginning, no indications of an end? the question deserves consideration; but the answer is not difficult. in all the lapse of geological time there has been an absolute uniformity of natural law. the same grand machinery of force and matter has been in use throughout all the ages, working out the great plan. yet the plan has been progressive and advancing, nevertheless. the uniformity has been in the methods, the results have presented a wondrous diversity and development. again, geology, in its oldest periods, fails to reach the beginning of things. it shows us how course after course of the building has been laid, and how it has grown to completeness, but it contains as yet no record of the laying of the foundation-stones, still less of the quarry whence they were dug. still the constant progress which we have seen points to a beginning which we have not seen; and the very uniformity of the process by which the edifice has been erected, implies a time when it had not been begun, and when its stones were still reposing in their native quarry. what, then, is the oldest condition of the earth actually shown to us by geology,--that which prevailed in the eozoic or laurentian period, when the oldest rocks known, those constituting the foundation-stones of our present continents, were formed and laid in their places? with regard to physical conditions, it was a time when our existing continents were yet in the bosom of the waters, when the ocean was almost universal, yet when sediments were being deposited in it as at present, while there were also volcanic foci, vomiting forth molten matter from the earth's hidden interior. then, as now, the great physical agencies of water and fire were contending with one another for the mastery, doing and undoing, building up and breaking down. but is this all? has the earth no earlier history? that it must have had, we may infer from many indications; but as to the nature of these earlier states, we can learn from conjecture and inference merely, and must have recourse to other witnesses then those rocky monuments which are the sure guides of the geologist. one fact bearing on these questions which has long excited attention, is the observed increase in temperature in descending into deep mines, and in the water of deep artesian wells--an increase which may be stated in round numbers at one degree of heat of the centigrade thermometer for every feet of depth from the surface. these observations apply of course to a very inconsiderable depth, and we have no certainty that this rate continues for any great distance towards the centre of the earth. if, however, we regard it as indicating the actual law of increase of temperature, it would result that the whole crust of the earth is a mere shell covering a molten mass of rocky matter. thus a very slight step of imagination would carry us back to a time when this slender crust had not yet formed, and the earth rolled through space an incandescent globe, with all its water and other vaporisable matters in a gaseous state. astronomical calculation has, however, shown that the earth, in its relation to the other heavenly bodies, obeys the laws of a rigid ball, and not of a fluid globe. hence it has been inferred that its actual crust must be very thick, perhaps not less then , miles, and that its fluid portion must therefore be of smaller dimensions then has been inferred from the observed increase of temperature. further, it seems to have been rendered probable, from the density of rocky matter in the solid and liquid states, that a molten globe would solidify at the centre as well as at the surface, and consequently that the earth must not only have a solid crust of great thickness, but also a solid nucleus, and that any liquid portions must be of the nature of a sheet or of detached masses intervening between these. on the other hand, it has recently been maintained that the calculations which are supposed to have established the great thickness of the crust, on the ground that the earth does not change its form in obedience to the attraction of the sun and moon, are based on a misconception, and that a molten globe with a thin crust would attain to such a state of equilibrium in this respect as not to be distinguishable from a solid planet. this view has been maintained by the french physicist, delaunay, and for some time it made geologists suppose that, after all, the earth's crust may be very thin. sir william thomson, however, and archdeacon pratt, have ably maintained the previous opinion, based on hopkins' calculations; and it is now believed that we may rest upon this as representing the most probable condition of the interior of the earth at present. another fact bearing on this point is the form of the earth, which is now actually a spheroid of rotation; that is, of such a shape as would result from the action of gravity and centrifugal force in the motion of a huge liquid drop rotating in the manner in which the earth rotates. of course it may be said that the earth may have been made in that shape to fit it for its rotation; but science prefers to suppose that the form is the result of the forces acting on it. this consideration would of course corroborate the deductions from that just mentioned. again, if we examine a map showing the distribution of volcanoes upon the earth, and trace these along the volcanic belt of western america and eastern asia, and in the pacific islands, and in the isolated volcanic regions in other parts of the world; and if we add to these the multitude of volcanoes now extinct, we shall be convinced that the sources of internal heat, of which these are the vents, must be present almost everywhere under the earth's crust. lastly, if we consider the elevations and depressions which large portions of the crust of the earth have undergone in geological time, and the actual crumpling and folding of the crust visible in great mountain chains, we arrive at a similar conclusion, and also become convinced that the crust has been not too thick to admit of extensive fractures, flexures, and foldings. there are, however, it must be admitted, theories of volcanic action, strongly supported by the chemical nature of the materials ejected by modern volcanoes, which would refer all their phenomena to the softening, under the continued influence of heat and water, of materials within the crust of the earth rather then under it.[a] still, the phenomena of volcanic action, and of elevation and subsidence, would, under any explanation, suppose intense heat, and therefore probably an original incandescent condition. [a] dr. t. sterry hunt, in silliman'a journal, . la place long ago based a theory of the originally gaseous condition of the solar system on the relation of the planets to each other, and to the sun, on their planes of revolution, the direction of their revolution, and that of their satellites. on these grounds he inferred that the solar system had been formed out of a nebulous mass by the mutual attraction of its parts. this view was further strengthened by the discovery of nebulae, which it might be supposed were undergoing the same processes by which the solar system was produced. this nebular theory, as it was called, was long very popular. it was subsequently supposed to be damaged by the fact that some of the nebulæ which had been regarded as systems in progress of formation were found by improved telescopes to be really clusters of stars, and it was inferred that the others might be of like character. the spectroscope has, however, more recently shown that some nebulæ are actually gaseous; and it has even been attempted to demonstrate that they are probably undergoing change fitting them to become systems. this has served to revive the nebular hypothesis, which has been further strengthened by the known fact that the sun is still an incandescent globe surrounded by an immense luminous envelope of vapours rising from its nucleus and condensing at its surface. on the other hand, while the sun may be supposed, from its great magnitude, to remain intensely heated, and while it will not be appreciably less powerful for myriads of years, the moon seems to be a body which has had time to complete the whole history of geological change, and to become a dry, dead, and withered world, a type of what our earth would in process of time actually become. [illustration: _figs. to ._--_ideal sections illustrating the genesis of the earth._ fig. . a vaporous world. fig. . a world with a central fluid nucleus (_b_) and a photosphere (_a_). fig. . the photosphere darkened, and a solid crust (_c_) and solid nucleus (_d_) formed. fig. . water (_e_) deposited on the crust, forming a universal ocean. fig. . the crust crumpled by shrinkage, land elevated, and the water occupying the intervening depressions. the figures are all of uniform size; but the circle (a) shows th diameter of the globe when in the state of fig. , and that marked (b) its diameter when in the state of fig. . in all the figures (_a_) represents vapour or air; (_b_) liquid rock; (_c_) solid rock as a crust; (_d_) solid nucleus; (_e_) water.] such considerations lead to the conclusion that the former watery condition of our planet was not its first state, and that we must trace it back to a previous reign of fire. the reasons which can be adduced in support of this are no doubt somewhat vague, and may in their details be variously interpreted; but at present we have no other interpretation to give of that chaos, formless and void, that state in which "nor aught nor nought existed," which the sacred writings and the traditions and poetry of ancient nations concur with modern science in indicating as the primitive state of the earth. let our first picture, then, be that of a vaporous mass, representing our now solid planet spread out over a space nearly two thousand times greater in diameter then that which it now occupies, and whirling in its annual round about the still vaporous centre of our system, in which at an earlier period the earth had been but an exterior layer, or ring of vapour. the atoms that now constitute the most solid rocks are in this state as tenuous as air, kept apart by the expansive force of heat, which prevents not only their mechanical union, but also their chemical combination. but within the mass, slowly and silently, the force of gravitation is compressing the particles in its giant hand, and gathering the denser toward the centre, while heat is given forth on all sides from the condensing mass into the voids of space without. little by little the denser and less volatile matters collect in the centre as a fluid molten globe, the nucleus of the future planet; and in this nucleus the elements, obeying their chemical affinities hitherto latent, are arranging themselves in compounds which are to constitute the future rocks. at the same time, in the exterior of the vaporous envelope, matters cooled by radiation into the space without, are combining with each other, and are being precipitated in earthy rain or snow into the seething mass within, where they are either again vaporised and sent to the surface or absorbed in the increasing nucleus. as this process advances, a new brilliancy is given to the faint shining of the nebulous matter by the incandescence of these solid particles in the upper layers of its atmosphere, a condition which at this moment, on a greater scale, is that of the sun; in the case of the earth, so much smaller in volume, and farther from the centre of the system, it came on earlier, and has long since passed away. this was the glorious starlike condition of our globe: in a physical point of view, its most perfect and beautiful state, when, if there were astronomers with telescopes in the stars, they might have seen our now dull earth flash forth--a brilliant white star secondary to the sun. but in process of time this passes away. all the more solid and less volatile substances are condensed and precipitated; and now the atmosphere, still vast in bulk, and dark and misty in texture, contains only the water, chlorine, carbonic acid, sulphuric acid, and other more volatile substances; and as these gather in dense clouds at the outer surface, and pour in fierce corrosive rains upon the heated nucleus, combining with its materials, or flashing again into vapour, darkness dense and gross settles upon the vaporous deep, and continues for long ages, until the atmosphere is finally cleared of its acid vapours and its superfluous waters.[b] in the meantime, radiation, and the heat abstracted from the liquid nucleus by the showers of condensing material from the atmosphere, have so far cooled its surface that a crust of slag or cinder forms upon it. broken again and again by the heavings of the ocean of fire, it at length sets permanently, and receives upon its bare and blistered surface the ever-increasing aqueous and acid rain thrown down from the atmosphere, at first sending it all hissing and steaming back, but at length allowing it to remain a universal boiling ocean. then began the reign of the waters, and the dominion of fire was confined to the abysses within the solid crust. under the primeval ocean were formed the first stratified rocks, from the substances precipitated from its waters, which must have been loaded with solid matter. we must not imagine this primeval ocean like our own blue sea, clear and transparent, but filled with earthy and saline matters, thick and turbid, until these were permitted to settle to the bottom and form the first sediments. the several changes above referred to are represented in diagrammatic form in figs. to . [b] hunt, "chemistry of the primeval earth," _silliman's journal_, . in the meantime all is not at rest in the interior of the new-formed earth. under the crust vast oceans of molten rock may still remain, but a solid interior nucleus is being crystallised in the centre, and the whole interior globe is gradually shrinking. at length this process advances so far that the exterior crust, like a sheet of ice from below which the water has subsided, is left unsupported; and with terrible earthquake-throes it sinks downward, wrinkling up into huge folds, between which are vast sunken areas into which the waters subside, while from the intervening ridges the earth's pent-up fires belch forth ashes and molten rocks. (fig. .) so arose the first dry land:-- "the mountains huge appear emergent, and their broad bare backs upheave into the clouds, their tops ascend the sky, so high as heaved the tumid hills, so low down sunk a hollow bottom, broad and deep, capacious bed of waters." the cloud was its garment, it was swathed in thick darkness, and presented but a rugged pile of rocky precipices; yet well might the "morning stars sing together, and all the sons of god shout with joy," when its foundations were settled and its corner-stone laid, for then were inaugurated the changes which were to lead to the introduction of life on the earth, and to all the future development of the continents. physical geographers have taught us that the great continents, whether we regard their coasts or their mountain chains, are built up on lines which run north-east and south-west, and north-west and south-east; and it is also observed that these lines are great circles of the earth tangent to the polar circle. further, we find, as a result of geological investigation, that these lines determined the deposition and the elevation of the oldest rocks known to us. hence it is fair to infer that these were the original directions of the first lines of fracture and upheaval. whether these lines were originally drawn by the influence of of the seasons on the cooling globe, or by the currents of its molten interior, or of the superficial ocean, they bespeak a most uniform and equable texture for the crust, and a definite law of fracture and upheaval; and they have modified all the subsequent action of the ocean as a depositor of sediment, and of the internal heat as a cause of alteration and movement of rocks. against these earliest belts of land the ocean first chafed and foamed. along their margins marine denudation first commenced, and the oceanic currents first deposited banks of sediment; and along these first lines have the volcanic orifices of all periods been most plentiful, and elevatory movements most powerfully felt. we must not suppose that the changes thus shortly sketched were rapid and convulsive. they must have required periods of enormous duration, all of which had elapsed before the beginning of geological time, properly so called. from sir william thomson's calculations, it would appear that the time which has elapsed from the first formation of a solid crust on the earth to the modern period may have been from seventy to one hundred millions of years, and the whole time from the vaporous condition of the solar system to the present, must of course have been still greater then even this enormous series of ages. such a lapse of time is truly almost inconceivable, but it is only a few days to him with whom one day is as a thousand years, and a thousand years as one day. how many and strange pictures does this series of processes call up! first, the uniform vaporous nebula. then the formation of a liquid nucleus, and a brilliant photosphere without. then the congealing of a solid crust under dark atmospheric vapours, and the raining down of acid and watery showers. then the universal ocean, its waves rolling unobstructed around the globe, and its currents following without hindrance the leading of heat and of the earth's rotation. then the rupture of the crust and the emergence of the nuclei of continents. some persons seem to think that by these long processes of creative work we exclude the creator, and would reduce the universe into a mere fortuitous concourse of atoms. to put it in more modern phrase, "given a quantity of detached fragments cast into space, then mutual gravitation and the collision of the fragments would give us the spangled heavens." but we have still to ask the old question, "whence the atoms?" and we have to ask it with all the added weight of our modern chemistry, so marvellous in its revelations of the original differences of matter and their varied powers of combination. we have to ask, what is gravitation itself, unless a mode of action of almighty power? we have to ask for the origin of of thousands of correlations, binding together the past and the future in that orderly chain of causes and effects which constitutes the plan of the creation. if it pleased god to create in the beginning an earth "formless and void" and to elaborate from this all that has since existed, who are we, to say that the plan was not the best? nor would it detract from our view of the creative wisdom and power if we were to hold that in ages to come the sun may experience the same change that has befallen the earth, and may become "black as sackcloth of hair," preparatory perhaps, to changes which may make him also the abode of life; or if the earth, cooling still further, should, like our satellite the moon, absorb all its waters and gases into its bosom, and become bare, dry, and parched, until there shall be "no more sea" how do we know but that then there shall be no more need of the sun, because a better light may be provided? or that there may not be a new baptism of fire in store for the earth, whereby, being melted with fervent heat, it may renew its youth in the fresh and heavenly loveliness of a new heaven and a new earth, free from all the evils and imperfections of the present? god is not slack in these things, as some men count slackness; but his ways are not like our ways. he has eternity wherein to do his work, and takes his own time for each of his operations. the divine wisdom, personified by a sacred writer, may well in this exalt his own office:-- "jehovah possessed me in the beginning of his way, before his work of old. i was set up from everlasting, from the beginning, or ever the earth was. when there were no deeps, t was brought forth; when there were no fountains abounding in water. before the mountains were settled, before the hills, was i brought forth: while as yet he had not made the earth, nor the plains, nor the higher part of the habitable world, when he gave the sea his decree, that her waters should not pass his limits; when he determined the foundations of the earth." chapter ii. the eozoic ages. the dominion of heat has passed away; the excess of water has been precipitated from the atmosphere, and now covers the earth as a universal ocean. the crust has folded itself into long ridges, the bed of the waters has subsided into its place, and the sea for the first time begins to rave against the shores of the newly elevated land, while the rain, washing the bare surfaces of rocky ridges, carries its contribution of the slowly wasting rocks back into the waters whence they were raised, forming, with the material worn from the crust by the surf, the first oceanic sediments. do we know any of these earliest aqueous beds, or are they all hidden from view beneath newer deposits, or have they been themselves worn away and destroyed by denuding agencies? whether we know the earliest formed sediments is, and may always remain, uncertain; but we do know certain very ancient rocks which may be at least their immediate successors. [illustration: fig. .--the laurentian nucleus of the american continent.] deepest and oldest of all the rocks we are acquainted with in the crust of the earth, are certain beds much altered and metamorphosed, baked by the joint action of heat and heated moisture--rocks once called azoic, as containing no traces of life, but for which i have elsewhere proposed the name "eozoic," or those that afford the traces of the earliest known living beings. these rocks are the laurentian series of sir william logan, so named from the laurentide hills, north of the river st. lawrence, which are composed of these ancient beds, and where they are more largely exposed then in any other region. it may seem at first sight strange that any of these ancient rocks should be found at the surface of the earth; but this is a necessary result of the mode of formation of the continents. the oldest rocks, thrown up in places into high ridges, have either not been again brought under the waters, or have lost by denudation the sediments once resting on them; and being of a hard and resisting nature, still remain; and often rise into hills of considerable elevation, showing as it were portions of the skeleton of the earth protruding through its superficial covering. such rocks stretch along the north side of the st. lawrence river from labrador to lake superior, and thence northwardly to an unknown distance, constituting a wild and rugged district often rising into hills feet high, and in the deep gorge of the saguenay forming cliffs , feet in sheer height from the water's edge. south of this great ridge, the isolated mass of the adirondack mountains rises to the height of , feet, rivalling the newer, though still very ancient, chain of the white mountains. along the eastern coast of north america, a lower ridge of laurentian rock, only appearing here and there from under the overlying sediments, is seen in newfoundland, in new brunswick, possibly in nova scotia, and perhaps farther south in massachusetts, and as far as maryland. in the old world, rocks of this age do not, so far as known, appear so extensively. they have been recognised in norway and sweden, in the hebrides, and in bavaria, and may, no doubt, be yet discerned in other localities. still, the grandest and most instructive development of these rocks is in north america; and it is there that we may best investigate their nature, and endeavour to restore the conditions in which they were deposited. it has been already stated that the oldest wrinkles of the crust of the globe take the direction of great circles of the earth tangent to the polar circle, forming north-east and south-west, and north-west and south-east lines. to such lines are the great exposures of laurentian rock conformed, as may be well seen from the map of north america (fig. ), taken from dana, with some additions. the great angular laurentian belt is evidently the nucleus of the continent, and consists of two broad bands or ridges meeting in the region of the great lakes. the remaining exposures are parallel to these, and appear to indicate a subordinate coast-line of comparatively little elevation. it is known that these laurentian exposures constitute the oldest part of the continent, a part which was land before any of the rocks of the shaded portion of the map were deposited in the bed of the ocean--all this shaded portion being composed of rocks of various geological ages resting on the older laurentian. it is further to be observed that the beds occurring in the laurentian bands are crumpled and folded in a most remarkable manner, and that these folds were impressed upon them before the deposition of the rocks next in geological age. what then are these oldest rocks deposited by the sea--the first-born of the reign of the waters? they are very different in their external aspect from the silt and mud, the sand and gravel, and the shell and coral rocks of the modern sea, or of the more recent geological formations. yet the difference is one in condition rather then composition. the members of this ancient aristocracy of the rocks are made of the same clay with their fellows, but have been subjected to a refining and crystallizing process which has greatly changed their condition. they have been, as geologists say, metamorphosed; and are to ordinary rocks what a china vase is to the lump of clay from which it has been made. deeply buried in the earth under newer sediments, they have been baked, until sandstones, gravels, and clays came out bright and crystalline, as gneiss, mica-schist, hornblende-schist, and quartzite--all hard crystalline rocks showing at first sight no resemblance to their original material, except in the regularly stratified or bedded arrangement which serves to distinguish them from igneous or volcanic rocks. in like manner certain finer, calcareous sediments have been changed into labrador feldspar, sometimes gay with a beautiful play of colour, and what were once common limestones appear as crystalline marble. if the evidence of such metamorphoses is asked for, this is twofold. in the first place, these rocks are similar in structure to more modern beds which have been partially metamorphosed, and in which the transition from the unaltered to the altered state can be observed. secondly, there are limited areas in the laurentian itself, in which the metamorphism has been so imperfect as to permit traces of the original character of the rocks to remain. it seems also quite certain, and this is a most important point for our sketch, that the laurentian ocean was not universal, but that there were already elevated portions of the crust capable of yielding sediment to the sea. in north america these laurentian rocks attain to an enormous thickness. this has been estimated by sir w. e. logan at , feet, so that the beds would, if piled on each other horizontally, be as high as the highest mountains on earth. they appear to consist of two great series, the lower and upper laurentian. even if we suppose that in the earlier stages of the world's history erosion and deposition were somewhat more rapid then at present, the formation of such deposits, probably more widely spread then any that succeeded them, must have required an enormous length of time. geologists long looked in vain for evidences of life in the laurentian period; but just as astronomers' have suspected the existence of unknown planets from the perturbations due to their attraction, geologists have guessed that there must have been some living things on earth even at this early time. dana and sterry hunt especially have committed themselves to such speculations. the reasons for this belief may be stated thus: ( .) in later formations limestone is usually an organic rock, produced by the accumulation of shells, corals, and similar calcareous organisms in the sea, and there are enormous limestones in the laurentian, constituting regular beds. ( .) in later formations coaly matter is an organic substance, derived from vegetables, and there are large quantities of laurentian carbon in the form of graphite. ( .) in later formations deposits of iron ores are almost always connected with the deoxidising influence of organic matters as an efficient cause of their accumulation, and the laurentian contains immense deposits of iron ore, occurring in layers in the manner of later deposits of these minerals. ( .) the limestone, carbon, and iron of the laurentian exist in association with the other beds in the same manner as in the later formations in which they are known to be organic. [illustration: fig. .--_eozoon canadense._ dawson. the oldest known animal. portion of skeleton, two-thirds natural size, (_a_) tabulated cell-wall, magnified, (_b_) portion of canal system, magnified.] in addition to this inferential evidence, however, one well-marked animal fossil has at length been found in the laurentian of canada, eozoon canadense, (fig. ), a gigantic representative of one of the lowest forms of animal life, which the writer had the honour of naming and describing in --its name of "dawn-animal" having reference to its great antiquity and possible connection with the dawn of life on our planet. in the modern seas, among the multitude of low forms of life with which they swarm, occur some in which the animal matter is a mere jelly, almost without distinct parts or organs, yet unquestionably endowed with life of an animal character. some of these creatures, the foraminifera, have the power of secreting at the surface of their bodies a calcareous shell, often divided into numerous chambers, communicating with each other, and with the water without, by pores or orifices through which, the animal can extend soft and delicate prolongations of its gelatinous body, which, when stretched out into the water, serve for arms and legs. in modern times these creatures, though extremely abundant in the ocean, are usually small, often microscopic; but in a fossil state there are others of somewhat larger size, though few equaling the eozoon, which seems to been a sessile creature, resting on the bottom of the sea, and covering its gelatinous body with a thin crust of carbonate of lime or limestone, adding to this, as it grew in size, crust after crust, attached to each other by numerous partitions, and perforated with pores for the emission of gelatinous filaments. this continued growth of gelatinous animal matter and carbonate of lime went on from age to age, accumulating great beds of limestone, in some of which the entire form and most minute structures of the creature are preserved, while in other cases the organisms have been broken up, and the limestones are a mere congeries of their fragments. it is a remarkable instance of the permanence of fossils, that in these ancient organisms the minutest pores through which the semi-fluid matter of these humble animals passed, have been preserved in the most delicate perfection. the existence of such creatures supposes that of other organisms, probably microscopic plants, on which they could feed. no traces of these have been observed, though the great quantity of carbon in the beds probably implies the existence of larger sea-weeds. no other form of animal has yet been distinctly recognized in the laurentian limestones, but there are fragments of calcareous matter which may have belonged to organisms distinct from eozoon. of life on the laurentian land we know nothing, unless the great beds of iron ore already referred to may be taken as a proof of land vegetation.[c] [c] it is proper to state here that some geologists and naturalists still doubt the organic nature of eozoon. their objections however, so far as stated publicly, have been shown to depend on misapprehension as to the structures observed and their state of preservation; and specimens recently found in comparatively unaltered rocks have indicated the true character of those more altered by metamorphism. to an observer in the laurentian period, the earth would have presented an almost boundless ocean, its waters, perhaps, still warmed with the internal heat, and sending up copious exhalations to be condensed in thick clouds and precipitated in rain. here and there might be seen chains of rocky islands, many of them volcanic, or ranges of bleak hills, perhaps clothed with vegetation the forms of which are unknown to us. in the bottom of the sea, while sand and mud and gravel were being deposited in successive layers in some portions of the ocean floor, in others great reefs of eozoon were growing up in the manner of reefs of coral. if we can imagine the modern pacific, with its volcanic islands and reefs of coral, to be deprived of all other forms of life, 'we should have a somewhat accurate picture of the eozoic time as it appears to us now. i say as it appears to us now; for we do not know what new discoveries remain to be made. more especially the immense deposits of carbon and iron in the laurentian would seem to bespeak a profusion of plant life in the sea or on the land, or both, second to that of no other period that succeeded, except that of the great coal formation. perhaps no remnant of this primitive vegetation exists retaining its form or structure; but we may hope for better things, and cherish the expectation that some fortunate discovery may still reveal to us the forms of the vegetation of the laurentian time. it is remarkable that the humbly organized living things which built up the laurentian limestones have continued to exist unchanged, save in dimensions, up to modern times; and here and there throughout the geological series we find beds of foraminiferous limestone, similar, except in the species of foraminifera composing them, to that of the laurentian. it is true that other kinds of creatures, the coral animals more particularly, have been introduced, and have proved equally efficient builders of limestones; but in the deeper parts of the sea the foraminifera continue to assert their pre-eminence in this respect, and the dredge reveals in the depths of our modern oceans beds of calcareous matter which may be regarded as identical in origin with the limestones formed in the period which is to us the dawn of organic life. many inquiries suggest themselves to the zoologist in connection with the life of the laurentian period. was eozoon the first creature in which the wondrous forces of animal life were manifested, when, in obedience to the divine fiat, the waters first "swarmed with swarmers," as the terse and expressive language of the mosaic record phrases it? if so, in contemplating this organism we are in the presence of one of the greatest of natural wonders--brought nearer then in any other case to the actual workshop of the almighty maker. still we cannot affirm that other creatures even more humble may not have preceded eozoon, since such humble organisms are known in the present world. attempts have often been made, and very recently have been renewed with much affirmation of success, to prove that such low forms of life may originate spontaneously from their materials in the waters; but so far these attempts merely prove that the invisible germs of the lower animals and plants exist everywhere, and that they have marvellous powers of resisting extreme heat and other injurious influences. we need not, therefore, be surprised if even lower forms then eozoon may have preceded that creature, or if some of these may be found, like the organisms said to live in modern boiling springs, to have had the power of existing even at a time when the ocean may have been almost in a state of ebullition. another problem is that of means of subsistence for the eozoic foraminifera. a similar problem exists in the case of the modern ocean, in whose depths live multitudes of creatures, where, so far as we know, vegetable matter, ordinarily the basis of life, cannot exist in a living condition. it is probable, however, from the researches of dr. wyville thompson, that this is to be accounted for by the abundance of life at the surface and in the shallower parts of the sea, and by the consequent diffusion through the water of organic matter in an extremely tenuous state, but yet sufficient to nourish these creatures. the same may have been the case in the eozoic sea, where, judging from the vast amount of residual carbon, there must have been abundance of organic matter, either growing at the bottom, or falling upon it from the surface; and as the eozoon limestones are usually free from such material, we may assume that the animal life in them was sufficient to consume the vegetable pabulum. on the other hand, as detached specimens of eozoon occur in graphitic limestones, we suppose that in some cases the vegetable matter was in excess of the animal, and this may have been either because of its too great exuberance, or because the water was locally too shallow to permit eozoon and similar creatures to nourish. these details we must for the present fill up conjecturally; bu the progress of discovery may give us further light as to the precise conditions of the beginning of life in the "great and wide sea wherein are moving things innumerable" and which is as much a wonder now as in the days of the author of the "hymn of creation"[d] in regard to the life that swarms in all its breadth and depth, the vast variety of that life, and its low and simple types, of which we can affirm little else then that they move. [d] psalm civ. the enormous accumulations of sediment on the still thin crust of the earth in the laurentian period--accumulations probably arranged in lines parallel to the directions of disturbance already indicated--weighed down the surface, and caused great masses of the sediment to come within the influence of the heated interior nucleus. thus, extensive metamorphism took place, and at length the tension becoming too great to be any longer maintained, a second great collapse occurred, crumpling and disturbing the crust, and throwing up vast masses of the laurentian itself, probably into lofty mountains--many of which still remain of considerable height, though they have been subjected to erosion throughout all the extent of subsequent geological time. the eozoic age, whose history we have thus shortly sketched, is fertile in material of thought for the geologist and the naturalist. until the labours of murchison, sedgwick, hall, and barrande had developed the vast thickness and organic richness of the silurian and cambrian rocks, no geologist had any idea of the extent to which life had reached backward in time. but when this new and primitive world of siluria was unveiled, men felt assured that they had now at last reached to the beginnings of life. the argument on this side of the question was thus put by one of the most thoughtful of english geologists, professor phillips: "it is ascertained that in passing downwards through the lower palæozoic strata, the forms of life grow fewer and fewer, until in the lowest cambrian rocks they vanish entirely. in the thick series of these strata in the longmynd, hardly any traces of life occur, yet these strata are of such a kind as might be expected to yield them.... the materials are fine-grained or arenaceous, with or without mica, in laminae or beds quite distinct, and of various thicknesses, by no means unlikely to retain impressions of a delicate nature, such as those left by graptolites, or mollusks, or annulose crawlers. indeed, one or two such traces are supposed to have been recognised, so that the almost total absence of the traces of life in this enormous series is best understood by the supposition that in these parts of the sea little or no life existed. but the same remark of the excessive rarity of life in the lower deposits is made in north america, in norway, and in bohemia, countries well searched for this very purpose, so that all our observations lead to the conviction that the lowest of all the strata are quite deficient of organic remains. the absence is general--it appears due to a general cause. is it not probable that during these very early periods the ocean and its sediments were nearly devoid of plants and animals, and in the earliest time of all, which is represented by sediments, quite deprived of such?" these words were written ten years ago, and about the same time were published in america those anticipations of the probability of life in the laurentian already referred to, and lyell was protesting against the name primordial, on the ground that it implied that we had reached the beginning of life, when this was not proved. yet there were elements of truth in both views. it is true now, as then, that the primordial seems to be a morning hour of life, having, as we shall see in our next paper, unmistakable signs about it of that approach to the beginning to which phillips refers. it is also true that it is not so early a morning hour as one who has not risen with the dawn might suppose, since with its apparently small beginnings of life it is almost as far removed from the eozoon reefs of the early laurentian on the one hand, as it is from the modern period on the other. the dawn of life seems to have been a very slow and protracted process, and it may have required as long a time between the first appearance of eozoon and the first of those primordial trilobites which the next period will introduce to our notice, as between these and the advent of adam. perhaps no lesson is more instructive then this as to the length of the working days of the almighty. another lesson lies ready for us in these same facts. theoretically, plants should have preceded animals; and this also is the assertion of the first chapter of genesis; but the oldest fossil certainly known to us is an animal. what if there were still earlier plants, whose remains are still to be discovered? for my own part, i can see no reason to despair of the discovery of an _eophytic_ period preceding the eozoic; perhaps preceding it through ages of duration to us almost immeasurable, though still within the possible time of the existence of the crust of the earth. it is even possible that in a warm and humid condition of the atmosphere, before it had been caused "to rain upon the earth" and when dense "mists ascended from the earth and watered the whole surface of the ground,"[e] vegetation may have attained to a profusion and grandeur unequalled in the periods whose flora is known to us. [e] genesis ii. . for a description of this eophytic period of genesis, see the author's "archaia," pp. _et seq._ but while eozoon thus preaches of progress and of development, it has a tale to tell of unity and sameness just as eozoon lived in the laurentian sea, and was preserved for us by the infiltration of its canals with siliceous mineral matters, so its successors and representatives have gone on through all the ages accumulating limestone in the sea bottom. to-day they are as active as they were then, and are being fossilised in the same way. the english chalk and the chalky modern mud of the atlantic sea-bed, are precisely similar in origin to the eozoic limestones. there is also a strange parallelism in the fact that in the modern seas foraminifera can live under conditions of deprivation of light and vital air, and of enormous pressure, under which few organisms of greater complexity could exist, and that in like manner eozoon could live in seas which were perhaps as yet unfit for most other forms of life. it has been attempted to press the eozoic foraminifers into the service of those theories of evolution which would deduce the animals of one geological period by descent with modification from those of another; but it must be confessed that eozoon proves somewhat intractable in this connection. in the first place, the creature is the grandest of his class, both in form and structure; and if, on the hypothesis of derivation, it has required the whole lapse of geological time to disintegrate eozoon into orbulina, globigerina, and other comparatively simple foraminifers of the modern seas, it may have taken as long, probably much longer, to develop eozoon from such simple forms in antecedent periods. time fails for such a process. again, the deep sea has been the abode of foraminifers from the first. in this deep sea they have continued to live without improvement, and with little material change. how little likely is it that in less congenial abodes they could have improved into higher grades of being; especially since we know that the result in actual fact of any such struggle for existence is merely the production of depauperated foraminifers? further, there is no link of connection known to us between eozoon and any of the animals of the succeeding primordial, which are nearly all essentially new types, vastly more different from eozoon then it is from many modern creatures. any such connection is altogether imaginary and unsupported by proof. the laws of creation actually illustrated by this primeval animal are only these: first, that there has been a progress in creation from few, low, and generalised types of life to more numerous, higher, and more specialised types; and secondly, that every type, low or high, was introduced at first in its best and highest form, and was, as a type, subject to degeneracy, and to partial or total replacement by higher types subsequently introduced. i do not mean that we could learn all this from eozoon alone; but that, rightly considered, it illustrates these laws, which we gather from the subsequent progress of the creative work. as to the mystery of the origin of living beings from dead matter, or any changes which they may have undergone after their creation, it is absolutely silent. chapter iii. the primordial, or cambrian age. between the time when _eozoon canadense_ flourished in the seas of the laurentian period, and the age which we have been in the habit of calling primordial, or cambrian, a great gap evidently exists in our knowledge of the succession of life on both of the continents, representing a vast lapse of time, in which the beds of the upper laurentian were deposited, and in which the laurentian sediments were altered, contorted, and upheaved, before another immense series of beds, the huronian, or lower cambrian, was formed in the bottom of the sea. eozoon and its companions occur in the lower laurentian. the upper laurentian has afforded no evidence of life; and even those conditions from which we could infer life are absent. the lowest cambrian, as we shall see, presents only a few traces of living beings. still, the physical history of this interval must have been most important. the wide level bottom of the laurentian sea was broken up and thrown into those bold ridges which were to constitute the nuclei of the existing continents. along the borders of these new-made lands intense volcanic eruptions broke forth, producing great quantities of lava and scoriæ and huge beds of conglomerate and volcanic ash, which are characteristic features of the older cambrian in both hemispheres. such conditions, undoubtedly not favourable to life, seem to have prevailed, and extended their influence very widely, so that the sediments of this period are among the most barren in fossils of any in the crust of the earth. if any quiet undisturbed spots existed in which the lower laurentian life could be continued and extended in preparation for the next period, we have yet discovered few of them. the experience of other geological periods would, however, entitle us to look for such oases in the lower cambrian desert, and to expect to find there some connecting links between the life of the eozoic and the very dissimilar fauna of the primordial. the western hemisphere, where the laurentian is so well represented, is especially unproductive in fossils of the immediately succeeding period. the only known exception is the occurrence of eozoon and of apparent casts of worm-burrows in rocks at madoc in canada, overlying the laurentian, and believed to be of huronian age, and certain obscure fossils of uncertain affinities, recently detected by mr. billings, in rocks supposed to be of this age, in newfoundland. here, however, the european series comes in to give us some small help. gümbel has described in bavaria a great series of gneissic rocks corresponding to the laurentian, or at least to the lower part of it; above these are what he calls the hercynian mica-slate and primitive clay-slate, in the latter of which he finds a peculiar species of eozoon, which he names _eozoon bavaricum_. in england also the longmynd groups of rocks in shropshire and in wales appears to be the immediate successor to the upper laurentian; and it has afforded some obscure "worm-burrows" or, perhaps, casts of sponges or fucoids, with a small shell of the genus _lingulella_, and also fragments of crustaceans (_palæeopyge_). the "fucoid sandstones" of sweden, believed to be of similar age, afford traces of marine plants and burrows of worms, while the harlech beds of wales have afforded to mr. hicks a considerable number of fossil animals, not very dissimilar from those of the upper cambrian. if these rocks are really the next in order to the eozoic, they show a marked advance in life immediately on the commencement of the primordial period. in ireland, the curious oldhamia, noticed below, appears to occur in rocks equally old. as we ascend, however, into the middle and upper parts of the cambrian, the menevian and lingula flag-beds of britain, and their equivalents in bohemia and scandinavia, and the acadian and potsdam groups of america, we find a rich and increasing abundance of animal remains, constituting the first primordial fauna of barrande. the rocks of the primordial are principally sandy and argillaceous, forming flags and slates, without thick limestones, and often through great thicknesses, very destitute of organic remains, but presenting some layers, especially in their upward extension, crowded with fossils. these are no longer mere protozoa, but include representatives of all the great groups of animals which yet exist, except the vertebrates. we shall not attempt any systematic classification of these; but, casting our dredge and tow-net into the primordial sea, examine what we collect, rather in the order of relative abundance then of classification. over great breadths of the sea bottom we find vast numbers of little bivalve shells of the form and size of a finger-nail, fastened by fleshy peduncles imbedded in the sand or mud; and thus anchored, collecting their food by a pair of fringed arms from the minute animals and plants which swarm in the surrounding waters. these are the _lingulæ_, from the abundance of which some of the primordial beds have received in england and wales the name of lingula flags. in america, in like manner, in some beds near st. john, new brunswick, the valves of these shells are so abundant as to constitute at least half of the material of the bed; and alike in europe and america, lingula and allied forms are among the most abundant primordial fossils. the lingulæ are usually reckoned to belong to the great sub-kingdom of mollusks, which includes all the bivalve and univalve shell-fish, and several other groups of creatures; but an able american naturalist, mr. morse, has recently shown that they have many points of resemblance to the worms; and thus, perhaps, constitute one of those curious old-fashioned "comprehensive" types, as they have been called, which present resemblances to groups of creatures, in more modern times quite distinct from each other. he has also found that the modern lingulæ are very tenacious of life, and capable of suiting themselves to different circumstances, a fact which, perhaps, has some connection with their long persistence in geological time. they are in any case members of the group of lamp-shells, creatures specially numerous and important in the earlier geological ages. [illustration: fig. .--life in the primordial sea. on the bottom are seen, proceeding from left to right, _oldhamia antiqua_, _lingulæ_, _arenicolæ_, _oldhamia radiata_, _paradoxides_, _histioderma_, _agnostus_, _oldhamia radiata_, _algæ_, and _lingulæ_. in the water are _hymenocaris_, different species of _trilobites_, and _pteropods_.] the lingulæ are especially interesting as examples of a type of beings continued almost from the dawn of life until now; for their shells, as they exist in the primordial, are scarcely distinguishable from those of members of the genus which still live. while other tribes of animals have run through a great number of different forms, these little creatures remain the same. another interesting point is a most curious chemical relation of the lingula, with reference to the material of its shell. the shells of mollusks generally, and even of the ordinary lamp-shells, are hardened by common limestone or carbonate of lime: the rarer substance, phosphate of lime, is in general restricted to the formation of the bones of the higher animals. in the case of the latter, this relation depends apparently on the fact that the albuminous substances on which animals are chiefly nourished require for their formation the presence of phosphates in the plant. hence the animal naturally obtains phosphate of lime or bone-earth with its food, and its system is related to this chemical fact in such wise that phosphate of lime is a most appropriate and suitable material for its teeth and bones. now, in the case of the lower animals of the sea, their food, not being of the nature of the richer land plants, but consisting mainly of minute algæ and of animals which prey on these, furnishes, not phosphate of lime, but carbonate. an exception to this occurs in the case of certain animals of low grade, sponges, etc., which, feeding on minute plants with siliceous cell-walls, assimilate the flinty matter and form a siliceous skeleton. but this is an exception of downward tendency, in which these animals approach to plants of low grade. the exception in the case of lingulæ is in the other direction. it gives to these humble creatures the same material for their hard parts which is usually restricted to animals of much higher rank. the purpose of this arrangement, whether in relation to the cause of the deviation from the ordinary rule or its utility to the animal itself, remains unknown. it has, however, been ascertained by dr. hunt, who first observed the fact in the case of the primordial lingulæ, that their modern successors coincide with them, and differ from their contemporaries among the mollusks in the same particular. this may seem a trifling matter, but it shows in this early period the origination of the difference still existing in the materials of which animals construct their skeletons, and also the wonderful persistence of the lingulæ, through all the geological ages, in the material of their shells. this is the more remarkable, in connection with our own very slender acquaintance with the phenomenon, in relation either to its efficient or final causes. before leaving the lingulæ, i may mention that mr. morse informs me that living specimens, when detached from their moorings, can creep like worms, leaving long furrows on the sand, and that they can also construct sand-tubes wherein to shelter themselves. this shows that some of the abundant "worm burrows" of the primordial may have been the work of these curious little shell-fishes, as well as, perhaps, some of the markings which have been described under the name of _eophyton_, and have been supposed, i think incorrectly, to be remains of land plants. in addition to lingula we may obtain, though rarely, lamp-shells of another type, that of the orthids, these have the valves hinged along a straight line, in the middle of which is a notch for the peduncle, and the valves are often marked with ribs or striae. the orthids were content with limestone for their shells, and apparently lived in the same circumstances with the lingulæ; and in the period succeeding the primordial they became far more abundant. yet they perished at an early stage of the world's progress, and have no representatives in the modern seas. in many parts of the primordial ocean the muddy bottom swarmed with crustaceans, relatives of our shrimps and lobsters, but of a form which differs so much from these modern shell-fishes that the question of their affinities has long been an unsettled one with zoologists. hundreds of species are known, some almost microscopic in size, others a foot in length. all are provided with a broad flat horseshoe-shaped head-plate, which, judging from its form and a comparison with the modern king-crabs or horseshoe-crabs, must have been intended as a sort of mud-plough to enable them to excavate burrows or hide themselves in the slimy ooze of the ocean bed. on the sides of this buckler are placed the prominent eyes, furnished with many separate lenses, on precisely the same plan with those of modern crustaceans and insects, and testifying, as buckland long ago pointed out, to the identity of the action of light in the ancient and the modern seas. the body was composed of numerous segments, each divided transversely into three lobes, whence they have received the name of _trilobites_, and the whole articulated, so that the creature could roll itself into a ball, like the modern slaters or wood-lice, which are not very distant relatives of these old crustaceans.[f] the limbs of trilobites were long unknown, and it was even doubted whether they had any; but recent discoveries have shown that they had a series of flat limbs useful both for swimming and creeping. the trilobites, under many specific and generic forms, range from the primordial to the carboniferous rocks, but are altogether wanting in the more recent formations and in the modern seas. the trilobites lived on muddy bottoms, and their remains are extremely abundant in shaly and slaty beds, though found also in limestone and sandstone. in the latter they have left most curious traces of their presence in the trails which they have produced. some of the most ancient sandstones have their surfaces covered with rows of punctured impressions (_protichnites_, first footprints), others have strange series of transverse grooves with longitudinal ones at the side (_climactichnites_, ladder footprints); others are oval burrows, marked with transverse lines and a ridge along the middle (_rusichnites_, wrinkle footprints). all of these so nearly resemble the trails and tracks of modern king-crabs that there can be little doubt as to their origin. many curious striated grooves and bifid marks, found on the surfaces of primordial beds, and which have been described as plants, are probably only the marks of the oral organs or feet of these and similar creatures, which passed their lives in grubbing for food in the soft, slimy ooze, though they could, no doubt, like the modern king-crabs, swim when necessary. some still more shrimp-like creatures, hymenocaris, which are found with them, certainly had this power. [f] woodward has recently suggested affinities of trilobites with the isopods or equal-footed crustaceans, on the evidence of a remarkable specimen with remains of feet described by billings. a lower type of annulose or ringed animal then that of the trilobites, is that of the worms. these creatures cannot be preserved in a fossil state, except in the case of those which inhabit calcareous tubes: but the marks which their jointed bodies and numerous side-bristles leave on the sand and mud may, when buried under succeeding sediments, remain; and extensive surfaces of very old rocks are marked in this way, either with cylindrical burrows or curious trails with side scratches looking like pinnate leaves. these constitute the genus _crusiana_, while others of more ordinary form belong to the genus _arenicolites_, so named from the common arenicola, or lobworm, whose burrows they are supposed to resemble. markings referable to seaweed also occur in the primordial rocks, and also some grotesque and almost inexplicable organisms known as _oldhamia_, which have been chiefly found in the primordial of ireland. one of the most common forms consists of a series of apparently jointed threads disposed in fan-like clusters on a central stem (_oldhamia antiqua_). another has a wider and simpler fan-like arrangement of filaments. these have been claimed by botanists as algæ, and have been regarded by zoologists as minute zoophytes, while some more sceptical have supposed that they may be mere inorganic wrinklings of the beds. this last view does not, however, seem tenable. they are, perhaps, the predecessors of the curious _graptolites_, which we shall have to represent in the silurian. singularly enough, foraminifera, the characteristic fossils of the laurentian, have been little recognised in the primordial, nor are there any limestones known so massive as those of the former series. there are, however, a number of remarkable organisms, which have usually been described as sponges, but are more probably partly of the nature of sponges and partly of that of foraminifera. of this kind are some of the singular conical fossils described by billings as _archæocyathus_, and found in the primordial limestone of labrador. they are hollow within, with radiating pores and plates, calcareous in some, and in others with siliceous spicules like those of modern sponges. some of them are several inches in diameter, and they must have grown rooted in muddy bottoms, in the manner of some of the deep-sea sponges of modern times. one species at least of these creatures was a true foraminifer, allied, though somewhat distantly, to eozoon. in some parts of the primordial sandstones, curious funnel-shaped casts in sand occur, sometimes marked with spiral lines. the name _histioderma_ has been given to some of these, and they have been regarded as mouths of worm-burrows. others of larger size have been compared to inverted stumps of trees. if they were produced by worms, some of these must have been of gigantic size, but billings has recently suggested that they may be casts of sponges that lived like some modern species imbedded in the sand. in accordance with this view i have represented these curious objects in the engraving, on the whole, the life of these oldest palæozoic rocks is not very abundant; but there are probably representatives of three of the great subdivisions of animals or, as some would reckon them, of four the protozoa, the radiata (coelenterata), the mollusca, and the annulosa. and it is most interesting thus to find in these very old rocks the modern subdivisions of animals already represented, and these by types some of them nearly allied to existing inhabitants of the seas i have endeavoured in the engraving to represent some of the leading forms of marine life in this ancient period. perhaps one of the most interesting discoveries in these rocks is that of rain-marks and shrinkage-cracks, in some of the very oldest beds--those of the longmynd in shropshire. on the modern muddy beach any ordinary observer is familiar with the cracks produced by the action of the sun and air on the dried surfaces left by the tides. such cracks, covered by the waters of a succeeding tide, may be buried in newer silt, and once preserved in this way are imperishable. in like manner, the pits left by passing showers of rain on the mud recently left bare by the tide may, when the mud has dried, become sufficiently firm to be preserved. in this way we have rain-marks of various geological ages; but the oldest known are those of the longmynd, where they are associated both with ripple-marks and shrinkage-cracks. we thus have evidence of the action of tides, of sun, and of rain, in these ancient periods just as in the present day. were there no land animals to prowl along the low tidal flats in search of food? were there no herbs or trees to drink in the rains and flourish in the sunshine? if there were, no bone or footprint on the shore, or drifted leaf or branch, has yet revealed their existence to the eyes of geologists the beds of the primordial age exist in england, in bohemia, in sweden and norway, and also in north america. they appear to have been deposited along the shores of the old laurentian continent, and probably some of them indicate very deep water. the primordial rocks are in many parts of the world altered and hardened. they have often assumed a slaty structure, and their bedding, and the fossils which they contain, are both affected by this. the usual view entertained as to what is called slaty structure is, that it depends on pressure, acting on more or less compressible material in some direction usually different from that of the bedding. such pressure has the effect of arranging all the flat particles as scales of mica, etc. in planes parallel to the compressing surface. hence, if much material of this kind is present in the sediment, the whole rock assumes a fissile character causing it to split readily into thin plates. that such yielding to pressure has actually taken place is seen very distinctly in microscopic sections of some slaty rocks, which often show not only a laminated structure, but an actual crumpling on a small scale, causing them to assume almost the aspect of woody fibre. such rocks often remind a casual observer of decaying trunks of trees, and sections of them under the microscope show the most minute and delicate crumpling. it is also proved by the condition of the fossils the beds contain. these are often distorted, so that some of them are lengthened and others shortened, and if specimens were selected with, that view, it would be quite easy to suppose that those lengthened by distortion are of different species from those distorted so as to be shortened. slaty cleavage and distortion are not, however, confined to primordial rocks, but occur in altered sediments of various ages. the primordial sediments must have at one time been very widely distributed, and must have filled up many of the inequalities produced by the rending and contortion of the laurentian beds. their thicker and more massive portions are, however, necessarily along the borders of the laurentian continents, and as they in their turn were raised up into land, they became exposed to the denuding action first of the sea, and afterwards of the rain and rivers, and were so extensively wasted away that only in a few regions do large areas of them remain visible. that of bohemia has afforded to barrande a great number of most interesting fossils. the rocks of st. david's in wales, those of shropshire in england, and those of wicklow in ireland are also of great interest; and next to these in importance are, perhaps, the huronian and acadian groups of north america, in which continent--as for example in nova scotia and in some parts of new england--there are extensive areas of old metamorphic rocks whose age has not been determined by fossils, but which may belong to this period. the question of division lines of formations is one much agitated in the case of the cambrian rocks. whether certain beds are to be called cambrian or silurian has been a point greatly controverted; and the terms primordial and primordial silurian have been used as means to avoid the raising of this difficulty. many of our division lines in geology are arbitrary and conventional, and this may be the case with that between the primordial and silurian, the one age graduating into the other. there appears to be, however, the best reason to recognise a distinct cambrian period, preceding the two great periods, those of the second and third faunas of barrande, to which the term silurian is usually applied. on the other hand, in so far as our knowledge extends at present, a strongly marked line of separation exists between the laurentian and primordial, the latter resting on the edges of the former, which seems then to have been as much altered as now. still a break of this kind may be, perhaps must be, merely local; and may vary in amount. thus, in some places we find rocks of silurian and later ages resting directly on the laurentian, without the intervention of the primordial. in any case, where a line of coast is steadily sinking, each succeeding deposit will overlap that which went before; and this seems to have been the case with the laurentian shore when the primordial and silurian were being deposited. hence over large spaces the primordial is absent, being probably buried up, except where exposed by denudation at the margin of the two formations. this occurs in several parts of canada, while the laurentian rocks have evidently been subjected to metamorphism and long-continued weathering before the lower silurian were deposited; and in some cases the latter rest on weather-worn and pitted surfaces, and are filled with angular bits of the underlying rock, as well as with drift-shells which have been cast on these old laurentian shores; while in other cases the silurian rests on smooth water-worn laurentian rocks, and is filled at the junction with well-rounded pebbles and grains of sand which have evidently been subjected to a more thorough attrition then those of the present beach. with respect to the line of division between the primordial and the next succeeding rocks, it will be seen that important movements of the continents occurred at the close of the cambrian, and in some places the cambrian rocks have been much disturbed before the deposition of the lower silurian. seated on some ancient promontory of the laurentian, and looking over the plain which, in the primordial and lower silurian periods was the sea, i have often wished for some shred of vegetable matter to tell what lived on that land when the primordial surf beat upon its shore, and washed up the trilobites and brachiopods of those old seas; but no rock has yet taken up its parable to reveal the secret, and the primordial is vocal only with the old story: "and god said, let the waters swarm with swarming living things, and it was so." so our picture of the period may represent a sea-bottom swarming with animals of low grade, some sessile, some locomotive; and we may merely suppose a distant shore with vegetation dimly seen, and active volcanoes; but a shore on which no foot of naturalist has yet trod to scan its productions. very different estimates have been formed of the amount of life in this period, according to the position given to its latest limit. taking some of the more modern views of this subject, we might have included among the primordial animals many additional creatures, which we prefer noticing in the silurian, since it may at least be affirmed that their head-quarters were in that age, even if they had a beginning in the primordial. it may be interesting here, however, to note the actual amount of life known to us in this period, taken in its largest scope. in doing this, i shall take advantage of an interesting table given by dr. bigsby,[g] and representing the state of knowledge in , and shall group the species in such a manner as to indicate the relative abundance of distinct types of structure. we find then-- plants (all, or nearly all, supposed to be sea-weeds, and some, probably, mere tracks or trails of animals) species. sponges, and similar creatures " corals and their allies " starfishes and their allies " worms " trilobites and other crustaceans " lamp-shells and other molluscoids " common bivalve mollusks " common univalve mollusks and their allies " higher mollusks, nautili, cuttle-fishes, etc. " --- in all " [g] "thesaurus siluricus." now in this enumeration we observe, in the first place, a representation of all the lower or invertebrate groups of the waters. we have next the remarkable fact that the radiata of cuvier, the lowest and most plant-like of the marine animals, are comparatively slenderly represented, yet that there are examples of their higher as well as of their lower forms. we have the further fact that the crustaceans, the highest marine animals of the annulose type, are predominant in the waters; and that in the mollusks the highest and lowest groups are most plentiful, the middle less so. the whole number of species is small, and this may arise either from our having here reached an early period in the history of life, or from our information being defective. both are probably true. still, of the animals known, we cannot say that the proportions of the different kinds depend on defective knowledge. there is no reason, for example, why corals should not have been preserved as well as trilobites, or why brachiopods should have been preserved rather then ordinary bivalves. the proportions, therefore, it may be more safe to reason from then the aggregate. in looking at these proportions, and comparing them with those of modern seas, we are struck with the great number of species representing some types either now extinct or comparatively rare: the trilobites and brachiopods more particularly. we are astonished at the enormous preponderance of these two groups, and especially of the trilobites. further, we observe that while some forms, like lingula and nautilus, have persisted down to modern times, others, like the trilobites and orthids, perished very early. in all this we can dimly perceive a fitness of living things to physical conditions, a tendency to utilise each type to the limit of its capacities for modification, and then to abandon it for something higher; a tendency of low types to appear first, but to appear in their highest perfection and variety; a sudden apparition of totally diverse plans of structure subserving similar ends simultaneously with each other, as for instance those of the mollusk and the crustacean; the appearance of optical and mechanical contrivances, as for example the compound eyes of the trilobite and the swimming float of the orthoceras, in all their perfection at first, just as they continue to this day in creatures of similar grade. that these and other similar things point to a uniform and far-reaching plan, no rational mind can doubt; and if the world had stopped short in the primordial period, and attained to no further development, this would have been abundantly apparent; though it shines forth more and more conspicuously in each succeeding page of the stony record. how far such unity and diversity can be explained by the modern philosophy of a necessary and material evolution out of mere death and physical forces, and how far it requires the intervention of a creative mind, are questions which we may well leave with the thoughtful reader, till we have traced this history somewhat further. chapter iv. the lower and upper silurian ages. by english geologists, the great series of formations which succeeds to the cambrian is usually included under the name silurian system, first proposed by sir roderick murchison. it certainly, however, consists of two distinct groups, holding the second and third faunas of barrande. the older of the two, usually called the lower silurian, is the upper cambrian of sedgwick, and may properly be called the _siluro-cambrian_. the newer is the true silurian, or silurian proper--the upper silurian of murchison. we shall in this chapter, for convenience, consider both in connection, using occasionally the term lower silurian as equivalent to siluro-cambrian. the silurian presents us with a definite physical geography, for the northern hemisphere at least; and this physical geography is a key to the life conditions of the time. the north american continent, from its great unbroken area, affords, as usual, the best means of appreciating this. in this period the northern currents, acting perhaps in harmony with old laurentian outcrops, had deposited in the sea two long submarine ridges, running to the southward from the extreme ends of the laurentian nucleus, and constituting the foundations of the present ridges of the rocky mountains and the alleghanies. between these the extensive triangular area now constituting the greater part of north america, was a shallow oceanic plateau, sheltered from the cold polar currents by the laurentian land on the north, and separated by the ridges already mentioned from the atlantic and pacific. it was on this great plateau of warm and sheltered ocean that what we call the silurian fauna lived; while of the creatures that inhabited the depths of the great bounding oceans, whose abysses must have been far deeper and at a much lower temperature, we know little. during the long silurian periods, it is true, the great american plateau underwent many revolutions, sometimes being more deeply submerged, and having clear water tenanted by vast numbers of corals and shell-fishes, at others rising so as to become shallow and to receive deposits of sand and mud; but it was always distinct from the oceanic area without. in europe, in like manner, there seems to have been a great internal plateau bounded by the embryo hills of western europe on the west, and harbouring a very similar assemblage of creatures to those existing in america. further, during these long periods there were great changes, from a fauna of somewhat primordial type up to a new order of things in the upper silurian, tending toward the novelties which were introduced in the succeeding devonian and carboniferous. we may, in the first place, sketch these changes as they occurred on the two great continental plateaus, noting as we proceed such hints as can be obtained with reference to the more extensive oceanic spaces. before the beginning of the age, both plateaus seem to have been invaded by sandy and muddy sediments charged at some periods and places with magnesian limestone; and these circumstances were not favourable to the existence or preservation of organic remains. such are the potsdam and calciferous beds of america and the tremadoc and llandeilo beds of england. the potsdam and tremadoc are by their fossils included in the cambrian, and may at least be regarded as transition groups. it is further to be observed, in the case of these beds, that if we begin at the west side of europe and proceed easterly, or at the east side of america and proceed westerly, they become progressively thinner, the greater amount of material being deposited at the edges of the future continents; just as on the sides of a muddy tideway the flats are higher, and the more coarse sediment deposited near the margin of the channel, and fine mud is deposited at a greater distance and in thinner beds. the cause, however, on the great scale of the atlantic, was somewhat different, ancient ridges determining the border of the channel. this statement holds good not only of these older beds, but of the whole of the silurian, and of the succeeding devonian and carboniferous, all deposited on these same plateaus. thus, in the case of the silurian in england and wales, the whole series is more then , feet thick, but in russia, it is less then , feet. in the eastern part of america the thickness is estimated at quite as great an amount as in europe, while in the region of the mississippi the silurian rocks are scarcely thicker then in russia, and consist in great part of limestones and fine sediments, the sandstones and conglomerates thinning out rapidly eastward of the appalachian mountains. in both plateaus the earlier period of coarse accumulations was succeeded by one in which was clear water depositing little earthy sediment, and this usually fine; and in which the sea swarmed with animal life, from the _débris_ of which enormous beds of limestone were formed the trenton limestone of america and the bala limestone of europe. the fossils of this part of the series open up to us the head-quarters of lower silurian life, the second great fauna of barrande, that of the upper cambrian of sedgwick; and in america more especially, the trenton and its associated limestones can be traced over forty degrees of longitude; and throughout the whole of this space its principal beds are composed entirely of comminuted corals, shells, and crinoids, and studded with organisms of the same kinds still retaining their forms. out of these seas, in the european area, arose in places volcanic islets, like those of the modern pacific. in the next succeeding era the clear waters became again invaded with muddy and sandy sediments, in various alternations, and with occasional bands of limestone, constituting the caradoc beds of britain and the utica and hudson river groups of america. during the deposition of these, the abounding life of the siluro-cambrian plateaus died away, and a middle group of sandstones and shales, the oneida and medina of america and the mayhill of england, form the base of the upper silurian. but what was taking place meanwhile in the oceanic areas separating our plateaus? these were identical with the basins of the atlantic and pacific, which already existed in this period as depressions of the earth's crust, perhaps not so deep as at present. as to the deposits in their deeper portions we know nothing; but on the margin of the atlantic area are some rocks which give us at least a little information. in the later part of the cambrian period the enormous thickness of the quebec group of north america appears to represent a broad stripe of deep water parallel to the eastern edge of the american plateau, and in which an immense thickness of beds of sand and mud was deposited with very few fossils, except in particular beds, and these of a more primordial aspect then those of the plateau itself. these rocks no doubt represent the margin of a deep atlantic area, over which cold currents destructive of life were constantly passing, and in which great quantities of sand and mud, swept from the icy regions of the north, were continually being laid. the researches of dr. carpenter and dr. wyville thomson show us that there are at present cold areas in the deeper parts of the atlantic, on the european side, as we have long known that they exist at less depths on the american side; and these same researches, with the soundings on the american banks, show that sand and gravel may be deposited not merely on shallows, but in the depths of the ocean, provided that these depths are pervaded by cold and heavy currents capable of eroding the bottom, and of moving coarse material. the quebec group in canada and the united states, and the metalliferous lower silurian rocks of nova scotia and newfoundland, destitute of great marine limestones and coral reefs, evidently represent deep and cold-water areas on the border of the atlantic plateau. at a later period, the beginning of the upper silurian, the richly fossiliferous and exceptional deposits of the island of anticosti, formed in the deep hollow of the gulf of st. laurence, show that when the plateau had become shallowed up by deposition and elevation, and converted into desolate sand-banks, the area of abundant life was transferred to the still deep atlantic basin and its bordering bays, in which the forms of lower silurian life continued to exist until they were mixed up with those of the upper silurian. if we turn now to these latter rocks, and inquire as to their conditions on our two great plateaus, we shall find a repetition of changes similar to those which occurred in the times preceding. the sandy shallows of the earlier part of this period give place to wide oceanic areas similar to those of the lower silurian; in these we find vast and thick coral and shell limestones, the wenlock of england and niagara of america, as rich in life as the limestones of the lower silurian, and with the generic and family forms similar, but the species for the most part different. in america these limestones were followed by a singularly shallow condition of the plateau, in which the surface was so raised as at times to be converted into separate salt lakes in which beds of salt were deposited. on both plateaus there were alternations of oceanic and shallow conditions, under which the lower helderberg and ludlow beds, the closing members of the silurian, were laid down. of the atlantic beds of this period we know little, except that the great limestones appear to be wanting, and to be replaced by sandy and muddy deposits, in some parts at least of the margins of the area. in some portions also of the plateaus and their margins, extensive volcanic outbursts seem to have occurred; so that the american plateau presented, at least in parts, the aspect of a coral sea with archipelagos of volcanic islands, the ejections from which became mixed with the aqueous deposits forming around them. having thus traced the interesting series of geographical conditions indicated by the silurian series, we may next take our station on one of the submerged plateaus, and inquire as to the new forms of life now introduced to our notice; and in doing so shall include the life of both the lower and upper silurian. [illustration: fig. .--fragment of lower silurian limestone, sliced and magnified ten diameters, showing the manner in which it is made up of fragments of corals, crinoids, and shells. (from a paper oil the microscopic structure of canadian limestone, "canadian naturalist.")] first, we may remark the vast abundance and variety of corals. the polyps, close relatives of the common sea-anemone of our coasts, which build up our modern coral reefs, were represented in the silurian seas by a great number of allied yet different forms, equally effectual in the great work of secreting carbonate of lime in stony masses, and therefore in the building-up of continents. let us note some of the differences. in the first place, whereas our modern coral-workers can show us but the topmost pinnacles of their creations, peeping above the surface of the sea in coral reefs and islands, the work of the coral animals of the silurian has been finished, by these limestones being covered with masses of new sediment consolidated into hard rock, and raised out of the sea to constitute a part of the dry land. in the silurian limestones we thus have, not merely the coral reefs, but the wide beds of comminuted coral, mixed with the remains of other animals, which are necessarily accumulated in the ocean bed around the reefs and islands. further, these beds, which we might find loose and unconsolidated in the modern sea, have their fragments closely cemented together in the old limestones. the nature of this difference can be well seen by comparing a fragment of modern coral or shell limestone from bermuda, with a similar fragment of the trenton limestone, both being sliced for examination under the microscope. the old limestone is black or greyish, the modern one is nearly white, because in the former the organic matter in the animal fragments has been carbonised or converted into coaly and bituminous matter. the old limestone is much more dense and compact, partly because its materials have been more closely compressed by superincumbent weight, but chiefly because calcareous matter in solution in water has penetrated all the interstices, and filled them up with a deposit of crystalline limestone. in examining a slice, however, under the microscope, it will be seen that the fragments of corals and other organisms are as distinct and well preserved as in the crumbling modern rock, except that they are perfectly imbedded in a paste of clear transparent limestone, or rather calcareous spar, infiltrated between them. i have examined great numbers of slices of these limestones, ever with new wonder at the packing of the organic fragments which they present. the hard marble-like limestones used for building in the silurian districts of europe and america, are thus in most cases consolidated masses of organic fragments. in the next place, the animals themselves must have differed somewhat from their modern successors. this we gather from the structure of their stony cells, which present points of difference indicating corresponding difference of detail in the soft parts. zoologists thus separate the rugose or wrinkled corals and the tabulate or floored corals of the silurian from those of the modern seas. the former must have been more like the ordinary coral animals; the latter were very peculiar, more especially in the close union of the cells, and in the transverse floors which they were in the habit of building across these cells as they grew in height. they presented, however, all the forms of our modern corals. some were rounded and massive in form, others delicate and branching. some were solitary or detached, others aggregative in communities. some had the individual animals large and probably showy, others had them of microscopic size. perhaps the most remarkable of all is the american _beatricea_,[h] which grew like a great trunk of a tree twenty feet or more in height, its solitary animal at the top like a pillar-saint, though no doubt more appropriate and comfortable; and multitudes of delicate and encrusting corals clinging like mosses or lichens to its sides. this creature belongs to the very middle of the silurian, and must have lived in great depths, undisturbed by swell or breakers, and sheltering vast multitudes of other creatures in its stony colonnades. [h] first described by mr. billings. it has been regarded as a plant, and as a cephalopod shell; but i believe it was a coral allied to _cystiphyllum_. [illustration: fig. .--life in the silurian age. on the bottom are seen, proceeding from left to right, corals (_stenopora_ and _beatricea_) and a gasteropod; _orthoceras_; coral (_patria_); crinoids, _lingulæ_, and cystideans; a _trilobite_ and _cyrtolites_. in the water is a large _pterygotus_, and under it a _trinucleus_. further on, are cephalopods, a heteropod, and fishes. at the surface, _phyllograptus_, _graptolithus_, and _bellerophon_. on the land, _lepidodendron_, _psilophyton_, and _prototaxites_.] lastly, the silurian corals nourished in latitudes more boreal then their modern representatives. in both hemispheres as far north as silurian limestones have been traced, well-developed corals have been found. on the great plateaus sheltered by laurentian ridges to the north, and exposed to the sun and to the warmer currents of the equatorial regions, they nourished most grandly and luxuriantly: but they lived also north of the laurentian bands in the arctic sea basins, though probably in the shallower and more sheltered parts. undoubtedly the geographical arrangements of the silurian period contributed to this. we have already seen how peculiarly adapted to an exuberant marine life were the submerged continents of the period; and there was probably little arctic land producing icebergs to chill the seas. the great arctic currents, which then as now flowed powerfully toward the equator, must have clung to the deeper parts of the ocean basins, while the return waters from the equator would spread themselves widely over the surface; so that wherever the arctic seas presented areas a little elevated out of the cold water bottom, there might be suitable abodes for coral animals. it has been supposed that in the silurian period the sea might have derived some appreciable heat from the crust of the earth below, and astronomical conditions have been suggested as tending to produce changes of climate; but it is evident that whatever weight may be due to these causes, the observed geographical conditions are sufficient to account for the facts of the case. it is also to be observed, that we cannot safely infer the requirements as to temperature of silurian coral animals from those of the tenants of the modern ocean. in the modern seas many forms of life thrive best and grow to the greatest size in the colder seas; and in the later tertiary period there were elephants and rhinoceroses sufficiently hardy to endure the rigours of an arctic climate. so there may have been in the silurian seas corals of much less delicate constitution then those now living. next to the corals we may place the crinoids, or stone-lilies--creatures abounding throughout the silurian seas, and realizing a new creative idea, to be expanded in subsequent geological time into all the multifarious types of star-fishes and sea-urchins. a typical crinoid, such as the _glyptocrinus_ of the lower silurian, consists of a flexible jointed stem, sometimes several feet in length, composed of short cylindrical discs, curiously articulated together, a box-like body on top made up of polygonal pieces attached to each other at the edges, and five radiating jointed arms furnished with branches and branchlets, or fringes, all articulated and capable of being flexed in any direction. such a creature has more the aspect of a flower then of an animal; yet it is really an animal, and subsists by collecting with its arms and drifting into its mouth minute creatures floating in the water. another group, less typical, but abundantly represented in the silurian seas, is that of the cystideans, in which the body is sack-like, and the arms few and sometimes attached to the body. they resemble the young or larvæ of crinoids. in the modern seas the crinoids are extremely few, though dredging in very deep water has recently added to the number of known species; but in the silurian period they had their birth, and attained to a number and perfection not afterwards surpassed. perhaps the stone-lilies of the upper silurian rocks of dudley, in england, are the most beautiful of palæozoic animals. judging from the immense quantities of their remains in some limestones, wide areas of the sea bottom must have been crowded with their long stalks and flower-like bodies, presenting vast submarine fields of these stony water-lilies. passing over many tribes of mollusks, continued or extended from the primordial--and merely remarking that the lamp-shells and the ordinary bivalve and univalve shell-fishes are all represented largely, more especially the former group, in the silurian--we come to the highest of the mollusca, represented in our seas by the cuttle-fishes and nautili, creatures which, like the crinoids, may be said to have had their birth in the silurian, and to have there attained to some of their grandest forms. the modern pearly nautilus shell, well known in every museum, is beautifully coiled in a disc-like form, and when sliced longitudinally shows a series of partitions dividing it into chambers, air-tight, and serving as a float to render the body of the creature independent of the force of gravity. as the animal grows it retracts its body toward the front of the shell, and forms new partitions, so that the buoyancy of the float always corresponds with the weight of the animal; while by the expansion and contraction of the body and removal of water from a tube or syphon which traverses the chambers, or the injection of additional water, slight differences can be effected, rendering the creature a very little lighter or heavier then the medium in which it swims. thus practically delivered from the encumbrance of weight, and furnished with long flexible arms provided with suckers, with great eyes and a horny beak, the nautilus becomes one of the tyrants of the deep, creeping on the bottom or swimming on the surface at will, and everywhere preying on whatever animals it can master. fortunately for us, as well as for the more feeble inhabitants of the sea, the nautili are not of great size, though some of their allies, the cuttle-fishes, which, however, want the floating apparatus, are sufficiently powerful to be formidable to man. in the silurian period, however, there were not only nautili like ours, but a peculiar kind of straight nautilus--the _orthoceratites_--which sometimes attained to gigantic size. the shells of these creatures may be compared to those of nautili straightened out, the chambers being placed in a direct line in front of each other. a great number of species have been discovered, many quite insignificant in size, but others as much as twelve feet in length and a foot in diameter at the larger end. indeed, accounts have been given of individuals of much larger growth. these large _orthoceratites_ were the most powerful marine animals known to us in the silurian, and must have been in those days the tyrants of the seas.[i] [i] zoologists will observe that i have, in the illustrations given the orthoceras the arms rather of a cuttle-fish then of a nautilus. the form of the outer chamber of the shell, i think, warrants this view of the structure of the animal, which must have been formed on a very comprehensive type. among the crustaceans, or soft shell-fishes of the silurian, we meet with the _trilobites_, continued from the primordial in great and increasing force, and represented by many and beautiful species; while an allied group of shell-fishes of low organization but gigantic size, the _eurypterids_, characteristic of the upper silurian, were provided with powerful limbs, long flexible bodies, and great eyes in the front of the head, and were sometimes several feet in length. instead of being mud grovellers, like the trilobites and modern king-crabs, these _eurypterids_ must have been swimmers, careering rapidly through the water, and probably active and predaceous. there were also great multitudes of those little crustaceans which are inclosed in two horny or shelly valves like a bivalve shell-fish, and the remains of which sometimes fill certain beds of silurian shale and limestone. no remains found in the silurian rocks have been more fertile sources of discussion then the so-called _graptolites_, or written stones--a name given long ago by linnæus, in allusion to the resemblance of some species having rows of cells on one side, to minute lines of writing. these little bodies usually appear as black coaly stains on the surface of the rock, showing a slender stem or stalk, with a row of little projecting cells at one side, or two rows, one on each side. the more perfect specimens show that, in many of the species at least, these fragments were branches of a complex organism spreading from a centre; and at this centre there is sometimes perceived a sort of membrane connecting the bases of the branches, and for which various uses have been conjectured. the branches themselves vary much in different species. they may be simple or divided, narrow, or broad and leaf-like, with one row of cells, or two rows of cells. hence arise generic distinctions into single and double graptolites, leaf and tree graptolites, net graptolites, and so on. but while it is easy to recognise these organisms, and to classify them in species and genera, it is not so easy to say what their affinities are with modern things. they are exclusively silurian, disappearing altogether at the close of this period, and, so far as we know, not succeeded by any similar creatures serving to connect them with modern forms. hence the most various conjectures as to their nature. they have been supposed to be plants, and have been successively referred to most of the great divisions of the lower animals. most recently they have been regarded by hall, nicholson,[j] and others, who have studied them most attentively, as zoophytes or hydroids allied to the sertularise, or tooth-corallines and sea-fir-corallines of our coasts, to the cell-bearing branches of which their fragments bear a very close resemblance. in this case, each of the little cells or teeth at the sides of the fibres must have been the abode of a little polyp, stretching out its tentacles into the water, and enjoying a common support and nutrition with the other polyps ranged with it. still the mode of life of the community of branching stems is uncertain. in some species there is a little radicle or spike at the base of the main stem, which may have been a means of attachment. in others the hollow central disk has been conjectured to have served as a float. occurring as the specimens do usually in shales and slates, which must have been muddy beds, they could not have been attached to stones or rocks, and they must have lived in clear water, either seated on the surface of the mud, attached to sea-weeds, or floating freely by means of hollow disks filled with air. after much thought on their structure and mode of occurrence, i am inclined to believe that in their younger stages they were attached, but by a very slender thread; that at a more advanced stage they became free, and acquiring a central membranous disk filled with air, floated by means of this at the surface, their long branches trailing in the waters below. they would thus be, with reference to their mode of life, though not to the details of their structure, prototypes of the modern portuguese man-of-war, which now drifts so gaily over the surface of the warmer seas. i have represented them in this attitude; but in case i should be mistaken, the reader may imagine it possible that they may be adhering to the lower surface of floating tangle. the head-quarters of the graptolites seem to be in the upper part of the cambrian, and in the siluro-cambrian, and they are widely distributed in europe, in america, and in australia. this very wide distribution of the species is probably connected with their floating and oceanic habits. [j] see also an able paper by carruthers, in the _geological magazine_, vol. v., p. . lastly, just as the silurian period was passing away, we find a new thing in the earth--vertebrate animals, represented by several species of shark-like fishes, which came in here as forerunners of the dynasty of the vertebrates, which from that day to this have been the masters of the world. these earliest vertebrates are especially interesting as the first known examples of a plan of structure which culminates only in man himself. they appear to have had cartilaginous skeletons; and in this and their shagreen-like skin, strong bony spines, and trenchant teeth, to have much resembled our modern sharks, or rather the dog-fishes, for they were of small size. one genus (_pteraspis_), apparently the oldest of the whole, belongs, however, to a tribe of mailed fishes allied to some of those of the old red sandstone. in both cases the groups of fishes representing the first known appearance of the vertebrates were allied to tribes of somewhat high organization in that class; and they asserted their claims to dominancy by being predaceous and carnivorous creatures, which must have rendered themselves formidable to their invertebrate contemporaries. coprolites, or fossil masses of excrement, which are found with them, indicate that they chased and devoured orthoceratites and sea-snails of various kinds, and snapped lingulæ and crinoids from their stalks; and we can well imagine that these creatures, when once introduced, found themselves in rich pasture and increased accordingly. space prevents us from following further our pictures of the animal life of the great silurian era, the monuments of which were first discovered by two of england's greatest geologists, murchison and sedgwick. how imperfect such a notice must be, may be learned from the fact that dr. bigsby, in his "thesaurus siluricus" in , catalogues , silurian species, of which only are known in the primordial. our illustration, carefully studied, may do more to present to the reader the teeming swarms of the silurian seas then our word-picture, and it includes many animal forms not mentioned above, more especially the curved and nautilus-like cuttle-fishes, those singular molluscous swimmers by fin or float known to zoologists as violet-snails, winged-snails or pteropods, and carinarias; and which, under various forms, have existed from the silurian to the present time. the old _lingulæ_ are also there as well as in the primordial, while the fishes and the land vegetation belong, as far as we yet know, exclusively to the upper silurian, and point forward to the succeeding devonian. we know as yet no silurian animal that lived on the land or breathed air. but our knowledge of land plants, though very meagre, is important. without regarding such obscure and uncertain forms as the _eophyton_ of sweden, hooker, page, and barrande have noticed, in the upper silurian, plants allied to the lycopods or club-mosses. i have found in the same deposits another group of plants allied to lycopods and pill-worts (psilophyton), and fragments of wood representing the curious and primitive type of pine-like trees known as _prototaxites_. these are probably only a small instalment of silurian land plants, such as a voyager might find floating in the sea on his approach to some unknown shore, which had not yet risen above his horizon. time and careful search will, no doubt, add largely to our knowledge. in the silurian, as in the cambrian, the head-quarters of animal life were in the sea. perhaps there was no animal life on the land; but here our knowledge may be at fault. it is, however, interesting to observe the continued operation of the creative fiat, "let the waters swarm with swarmers" which, beginning to be obeyed in the eozoic age, passes down through all the periods of geological time to the "moving things innumerable" of the modern ocean. can we infer anything further as to the laws of creation from these silurian multitudes of living things? one thing we can see plainly, that the life of the silurian is closely related to that of the cambrian. the same generic and ordinal forms are continued. even some species may be identical. does this indicate direct genetic connection, or only like conditions in the external world correlated with likeness in the organic world? it indicates both. first, it is in the highest degree probable that many of the animals of the lower silurian are descendants of those of the cambrian. sometimes these descendants may be absolutely unchanged. sometimes they may appear as distinct varieties. sometimes they may have been regarded as distinct though allied species. the continuance in this manner of allied forms of life is necessarily related to the continuance of somewhat similar conditions of existence, while changes in type imply changed external conditions. but is this all? i think not; for there are forms of life in the silurian which cannot be traced to the cambrian, and which relate to new and even prospective conditions, which the unaided powers of the animals of the earlier period could not have provided for. these new forms require the intervention of a higher power, capable of correlating the physical and organic conditions of one period with those of succeeding periods. whatever powers may be attributed to natural selection or to any other conceivable cause of merely genetic evolution, surely prophetic gifts cannot be claimed for it; and the life of all these geological periods is full of mute prophecies to be read only in the light of subsequent fulfilments. the fishes of the upper silurian are such a prophecy. they can claim no parentage in the older rocks, and they appear at once as kings of their class. with reference to the silurian itself, they are of little consequence; and in the midst of its gigantic forms of invertebrate life they seem almost misplaced. but they predict the coming devonian, and that long and varied reign of vertebrate life which culminates in man himself. no such prophetic ideas are represented by the giant crustaceans and cuttle-fishes and swarming graptolites. they had already attained their maximum, and were destined to a speedy and final grave in the silurian, or to be perpetuated only in decaying families whose poverty is rendered more conspicuous by the contrast with the better days gone by. the law of creation provided for new types, and at once for the elevation and degradation of them when introduced; and all this with reference to the physical conditions not of the present only but of the future. such facts, which cannot be ignored save by the wilfully blind, are beyond the reach of any merely material philosophy. the little that we know of silurian plants is as eloquent of plan and creation as that which we can learn of animals. i saw not long ago a series of genealogies in geological time reduced to tabular form by that ingenious but imaginative physiologist, haeckel. in one of these appeared the imaginary derivation of the higher plants from algæ or sea-weeds. nothing could more curiously contradict actual facts. algæ were apparently in the silurian neither more nor less elevated then in the modern seas, and those forms of vegetable life which may seem to bridge over the space between them and the land plants in the modern period, are wanting in the older geological periods, while land plants seem to start at once into being in the guise of club-mosses, a group by no means of low standing. our oldest land plants thus represent one of the highest types of that cryptogamous series to which they belong, and moreover are better developed examples of that type then those now existing. we may say, if we please, that all the connecting links have been lost; but this is begging the whole question, since no thing 'but the existence of such links could render the hypothesis of derivation possible. further, the occurrence of any number of successive yet distinct species would not be the kind of chain required, or rather would not be a chain at all. yet in some respects development is obvious in creation. old forms of life are often embryonic, or resemble the young of modern animals, but enlarged and exaggerated, as if they had overgrown themselves and had prematurely become adult. old forms are often generalized, or less specific in their adaptations then those of modern times. there is less division of labour among them. old forms sometimes not only rise to the higher places in their groups, but usurp attributes which in later times are restricted to their betters. old forms are often gigantic in size in comparison with their modern successors, which, if they could look back on their predecessors, might say, "there were giants in those days." some old forms have gone onward in successive stages of elevation by a regular and constant gradation. others have remained as they were through all the ages, some have no equals in their groups in modern days. all these things speak of order, but of order along with development, and this development not evolution; unless by this term we understand the emergence into material facts of the plans of the creative mind. these plans we may hope in some degree to understand, though we may not be able to comprehend the mode of action of creative power any more then the mode in which our own thought and will act upon the machinery of our own nerves. still, the power is not the less real, that we are ignorant of its mode of operation. the wind bloweth whither it listeth, and we feel its strength, though we may not be able to calculate the wind of to-morrow or the winds of last year. so is the spirit of god when it breathes into animals the breath of life, or the almighty word when it says, "let the waters bring forth." chapter v. the devonian age. paradoxical as it may appear, this period of geological history has been held as of little account, and has even been by some geologists regarded as scarcely a distinct age, just because it was one of the most striking and important of the whole. the devonian was an age of change and transition, in both physical and organic existence; and an age which introduced, in the northern hemisphere at least, more varied conditions of land and water and climate then had previously existed. hence, over large areas of our continents, its deposits are irregular and locally diverse; and the duration and importance of the period are to be measured rather by the changes and alterations of previous formations, and the ejection of masses of molten rock from beneath, then by a series of fossiliferous deposits. nevertheless, in some regions in north america and eastern europe, the formations of this era are of vast extent and volume, those of north america being estimated at the enormous thickness of , feet, while they are spread over areas of almost continental breadth. at the close of the upper silurian, the vast continental plateaus of the northern hemisphere were almost wholly submerged. no previous marine limestone spreads more widely then that of the upper silurian, and in no previous period have we much less evidence of the existence of dry land; yet before the end of the period we observe, in a few fragments of land plants scattered here and there in the marine limestones--evidence that islands rose amid the waste of waters. as it is said that the sailors of columbus saw the first indications of the still unseen western continent in drift canes, and fragments of trees floating in mid ocean, so the voyager through the silurian seas finds his approach to the verdant shores of the devonian presaged by a few drift plants borne from shores yet below the horizon. the small remains of land in the upper silurian were apparently limited to certain clusters of islands in the north-eastern part of america and north-western part of europe, with perhaps some in the intervening atlantic on these limited surfaces grew the first land plants certainly known to us--herbs and trees allied to the modern club-mosses, and perhaps forests of trees allied to the pines, though of humbler type; and this wide upper silurian sea, with archipelagos of wooded islands, may have continued for a long time. but with the beginning of the devonian, indications of an unstable condition of the earth's crust began to develop themselves. new lands were upheaved; great shallow, muddy, and sandy flats were deposited around them the domains of corals and sea-weeds were contracted and on banks, and in shallows and estuaries, there swarmed shoals of fishes of many species, and some of them of most remarkable organization. on the margins of these waters stretched vast swamps, covered with a rank vegetation. but the period was one of powerful igneous activity. volcanoes poured out their molten rocks over sea and land, and injected huge dykes of trap into the newly-formed beds. the land was shaken with earthquake throes, and was subject to many upheavals and subsidences. violent waves desolated the coasts, throwing sand and gravel over the flats, and tearing up newly-deposited beds; and poisonous exhalations, or sudden changes of level, often proved fatal to immense shoals of fishes. this was the time of the lower devonian, and it is marked, both in the old world and the new, by extensive deposits of sandstones and conglomerates. but the changes going on at the surface were only symptomatic of those occurring beneath. the immense accumulations of silurian sediment had by this time so overweighted certain portions of the crust, that great quantities of aqueous sediment had been pressed downward into the heated bowels of the earth, and were undergoing, under an enormous weight of superincumbent material, a process of baking and semi-fusion. this process was of course extremely active along the margins of the old silurian plateaus, and led to great elevation of land, while in the more central parts of the plateaus the oceanic conditions still continued; and in the middle devonian, in america at least, one of the most remarkable and interesting coral limestones in the world--the corniferous limestone--was deposited. in process of time, however, these clear waters became shallow, and were invaded by muddy sediments; and in the upper devonian the swampy flats and muddy shallows return in full force, and in some degree anticipate the still greater areas of this kind which existed in the succeeding coal formation. such is a brief sketch of the devonian, or, as it may be better called in america, from the vast development of its beds on the south side of lake erie, the _erian_ formation. in america the marine beds of the devonian were deposited on the same great continental plateau which supported the seas of the upper and lower silurian, and the beds were thicker towards the east and thinned towards the west, as in the case of the older series. but in the devonian there was much, land in the north-east of america; and on the eastern margin of this land, as in gaspé and new brunswick, the deposits throughout the whole period were sandstones and shales, without the great coral limestones of the central plateau. something of the same kind occurred in europe, where, however, the area of devonian sea was smaller. there the fossiliferous limestones of the middle devonian in devon, in the eifel district, in france and in russia, represent the great corniferous limestone of america; while the sandstones of south wales, of ireland, and of scotland, resemble the local conditions of gaspé and new brunswick, and belonged to a similar area in the north-west of europe, in which shallow water and land conditions prevailed during the whole of the devonian, and which was perhaps connected with the corresponding region in eastern america by a north atlantic archipelago, now submerged. this whole subject is so important to the knowledge of the devonian, and of geology in general, that i may be pardoned for introducing it here in a tabular form, taking the european series from etheridge's excellent and exhaustive paper in the "journal of the geological society." devonian of erian. divisions. central areas. devon. rhen. prussia. new york. {pilton group:-- clymenia, cypridina, chemung and portage. { brown calcareous etc. shales, sandstones upper { shales, brown and limestones, and and shales. { yellow sandstone. sandstones. plants and marine { land plants and plants and marine shells. { marine shells. shells. {ilfracombe group:-- eifel limestone, hamilton shales, { grey and red calceola shales, and corniferous middle { sandstones and etc. or cherty { flags, calcareous corals, shells, limestone. { slates and etc. many corals and { limestones, with shells, also { corals, etc. plants. {lynton group:-- coblentz and schoharie and { bed and purple wissenbach shales, caudagalli grits. lower { sandstones. marine rhenish greywacke, oriskany { shells, etc. spinier sandstones. { sandstone. marine shells. { marine shells. divisions. marginal areas. scotland. ireland. gaspé and new brunswick. {yellow and red yellow and red red and grey { sandstones. sandstones, etc. sandstones, grits upper {fishes and plants. plants, fishes, and shales, and { etc. conglomerates of { gaspé and mispeck. { plants. {red shales and grits and grey and red { sandstones, and sandstones of sandstones, and middle { conglomerates. dingle. grey and dark {caithness flags. shales. gaspé {fishes and plants. and st. john. { many plants and { fishes. {flagstones, shales glengariff grits, sandstone and { and conglomerates. etc. conglomerate. lower {fishes and plants. gaspé and st. { john. { plants and fishes. a glance at this table suffices to show that when we read hugh miller's graphic descriptions of the old red sandstone of scotland, with its numerous and wonderful fishes, we have before us a formation altogether distinct from that of devonshire or the eifel. but the one represents the shallow, and the other the deeper seas of the same period. we learn this by careful tracing of the beds to their junction with, corresponding series, and by the occasional occurrence of the characteristic fishes of the scottish strata in the english and german beds. in like manner a geologist who explores the gaspé sandstones or the new brunswick shales has under his consideration a group of beds very dissimilar from that which he would have to study on the shores of lake erie. but here again identity of relations to the silurian below and the carboniferous above, shows the contemporaneousness of the beds, and this is confirmed by the occurrence in both series of some of the same plants and shells and fishes. it will further be observed that it is in the middle that the greatest difference occurs. sand and mud and pebble-banks were almost universal over our two great continental plateaus in the older and newer devonian. but in the middle there were in some places deeper waters with coral reefs, in others shallow flats and swamps rich in vegetation. herein we see the greater variety and richness of the devonian. had we lived in that age, we should not have seen great continents like those that now exist, but we could have roamed over lovely islands with breezy hills and dense lowland jungles, and we could have sailed over blue coral seas, glowing below with all the fanciful forms and brilliant colours of polyp life, and filled with active and beautiful fishes. especially did all these conditions culminate in the middle devonian, when what are now the continental areas of the northern hemisphere must have much resembled the present insular and oceanic regions of the south pacific. out of the rich and varied life of the devonian i may select for illustration its corals, its crustaceans, its fishes, its plants, and its insects. [illustration: fig. .--corals, fishes, and crustaceans of the devonian in the foreground are corals of the genera _favosites_, _michelina_, _phillipsatrea_, _zaphrentis_, _blothrophyllum_, and _syringopora_, and the seaweed spirephyton; also fishes of the genera _cephalaspis_ and _pterichthys_. above are _pterygotus_ and _dinichtys_, with fishes of the genera _diplacanthus_, _osteolepis_, _holoptychius_, _pteraspis_, _coccosteus_, etc. the distant land had _lepidodendra_, pines and tree-ferns.] the central limestones of the devonian may be regarded as the head-quarters of the peculiar types of coral characteristic of the palæozoic age. here they were not only vastly numerous, but present some of their grandest and also their most peculiar forms. edwards and haime, in their "monograph of british fossil corals" in , enumerate one hundred and fifty well-ascertained species, and the number has since been largely increased; i have no doubt that my friend dr. bigsby, in his forth-coming "thesaurus devonicus," will more then double it. in the devonian limestones of england, as for instance at torquay, the specimens, though abundant and well preserved as to their internal structure, are too firmly imbedded in the rock to show their external forms. in the devonian of the continent of europe much finer specimens occur; but, perhaps, in no part of the world is there so clear an exhibition of them as in the devonian limestones of the united states and canada. sir charles lyell thus expresses his admiration of the exposure of these corals, which he saw at the falls of the ohio, near louisville. he says, "although the water was not at its lowest, i saw a grand display of what may be termed an ancient coral-reef, formed by zoophytes which flourished in a sea of earlier date then the carboniferous period. the ledges of horizontal limestone, over which the water flows, belong to the devonian group, and the softer parts of the stone have decomposed and wasted away, so that the harder calcareous corals stand out in relief. many branches of these zoophytes project from their erect stems precisely as if they were living. among other species i observed large masses, not less then five feet in diameter, of _favosites gothlandica_, with its beautiful honeycomb structure well displayed. there was also the cup-shaped _cyathophyllum_, and the delicate network of _fenestella_, and that elegant and well-known european species of fossil, the chain coral, _catenipora escharoides_, with a profusion of others which it would be tedious to all but the geologist to enumerate. although hundreds of fine specimens have been detached from these rocks to enrich the museums of europe and america, another crop is constantly working its way out under the action of the stream, and of the sun and rain in the warm season when the channel is laid dry."[k] these limestones have been estimated to extend, as an almost continuous coral reef, over the enormous area of five hundred thousand square miles of the now dry and inland surface of the great american continental plateau. the limestones described by sir charles are known in the western states as the "cliff limestone." in the state of new york and in western canada the "corniferous limestone," so called from the masses of hornstone, like the flint of the english chalk, contained in it, presents still more remarkable features. the corals which it contains have been replaced by the siliceous or flinty matter in such a manner that, when the surrounding limestone weathers away, they remain projecting in relief in all the beauty of their original forms. not only so, but on the surface of the country they remain as hard siliceous stones, and may be found in ploughing the soil and in stone fences and roadside heaps, so that tons of them could often be collected over a very limited space. when only partly disengaged from the matrix, the process may be completed by immersing them in a dilute acid. the beauty of these specimens when thus prepared is very great not at all inferior to that of modern corals, which they often much resemble in general form, though differing in details of structure. one of the most common forms is that of the _favosites_, or honeycomb coral, presenting regular hexagonal cells with transverse floors or tabulæ. of these there are several species, usually flat or massive in form; but one species, _f. polymorpha_, branches out like the modern stag-horn corals. another curious form, _michelina_, looks exactly like a mass of the papery cells of the great american hornet in a petrified state, and the convex floors simulate the covers of the cells, so that it is quite common to find them called fossil wasps' nests. some of the largest belong to the genus _phillipsastrea_ or _smithia_, which hugh miller has immortalized by comparing its crowded stars, with confluent rays, to the once-popular calico pattern known as "lane's net"--a singular instance of the accidental concurrence of a natural and artificial design. another very common type is that of the conical _zaphrentis_, with a deep cut at top to lodge the body of the animal, whose radiating chambers are faithfully represented by it's delicate lamellæ. perhaps the most delicate of the whole is the _syringopora_, with its cylindrical worm-like pipes bound together by transverse processes, and which sometimes can be dissolved out in all its fragile perfection by the action of an acid on a mass of corniferous limestone filled with these corals in a silicified state. [k] "travels in north america." second series. these devonian corals, like those of the silurian, belong to the great extinct groups of tabulate and rugose corals; groups which present, on the one hand, points of resemblance to the ordinary coral animals of the modern seas, and, on the other, to those somewhat exceptional corals, the millepores, which are produced by another kind of polyp, the hydroids. some of them obviously combine properties belonging to both, as, for example, the radiating partitions with the arrangement of the parts in multiples of four, the horizontal floors, and the external solid wall; and this fact countenances the conclusion that in these old corals we have a group of high and complex organization, combining properties now divided between two great groups of animals, neither of them probably, either in their stony skeletons or the soft parts of the animal, of as high organization as their paleozoic predecessors. this sort of disintegration of composite types, or dissolution of old partnerships, seems to have been no unusual occurrence in the history of life.[l] [l] verril has suggested that the tabulata may be divided into two groups, one referable to actinoids, the other to hydroids. if the devonian witnessed the culmination of the palæozoic corals, its later stages saw the final decadence of the great dynasty of the trilobites. of these creatures there are in the devonian some large and ornate species, remarkable for their spines and tubercles; as if in this, the latter day of their dominion, they had fallen into habits of luxurious decoration unknown to their sterner predecessors, and at the same time had found it necessary to surround their now disputed privileges with new safeguards of defensive armour. not improbably the decadence of the trilobites may have been connected with the introduction of the numerous and formidable fishes of the period. but while the venerable race of the trilobites was preparing to fight its last and unsuccessful battle, another and scarcely less ancient tribe of crustaceans, the eurypterids, already strong in the silurian, was armed with new and formidable powers. the _pterygotus anglicus_, which should have been named _scoticus_, since its head-quarters are in scotland, was in point of size the greatest of known crustaceans, recent or fossil. according to mr. henry woodward, who has published an admirable description and figures of the creature in the palæontographical society's memoirs, it must have been six feet in length, and nearly two feet in breadth. its antennæ were, unlike the harmless feelers of modern crustacea, armed with powerful claws. two great eyes stood in the front of the head, and two smaller ones on the top. it had four pairs of great serrated jaws, the largest as wide as a man's hand. at the sides were a pair of powerful paddles, capable of urging it swiftly through the water as it pursued its prey; and when attacked by any predaceous fish, it could strike the water with its broad tail, terminated by a great flat "telson," and retreat backward with the rapidity of an arrow. woodward says it must have been the "shark of the devonian seas;" rather, it was the great champion of the more ancient family of the lobsters, set to arrest, if possible, the encroachments of the coming sharks. the trilobites and eurypterids constitute a hard case for the derivationists. unlike those melchisedeks, the fishes of the silurian, which are without father or mother, the devonian crustaceans may boast of their descent, but they have no descendants. no distinct link connects them with any modern crustaceans except the limuli, or horse-shoe crabs; and here the connection is most puzzling, for while there seems some intelligible resemblance between the adult eurypterids and the horse-shoe, or king-crabs, the latter, in their younger state, rather resemble trilobites, as dr. packard has recently shown. thus the two great tribes of eurypterids and trilobites have united in the small modern group of king-crabs, while on the other hand, there are points of resemblance, as already stated, between trilobites and isopods, and the king-crabs had already begun to exist, since one species is now known in the upper silurian. so puzzling are these various relationships, that one naturalist of the derivationist school has recently attempted to solve the difficulty by suggesting that the trilobites are allied to the spiders! thus nature sports with our theories, showing us in some cases, as in the corals and fishes, partnerships split up into individuals, and in others distinct lines of being converging and becoming lost in one slender thread. barrande, the great palæontologist of bohemia, has recently, in an elaborate memoir on the trilobites, traced these and other points through all their structures and their whole succession in geological time thereby elaborating a most powerful inductive argument against the theory of evolution, and concluding that, so far from the history of these creatures favouring such a theory, it seems as if expressly contrived to exclude its possibility. but, while the gigantic eurypterids and ornate trilobites of the devonian were rapidly approaching their end, a few despised little crustaceans,--represented by the _amphipeltis_ of new brunswick and _kampecaris_ of scotland,--were obscurely laying the foundation of a new line of beings, that of the stomapods, destined to culminate in the squillas and their allies, which, however different in structure, are practically the eurypterids of the modern ocean. so change the dynasties of men and animals. "thou takest away their breath, they die, they return to their dust; thou sendest forth thy spirit, they are created; thou renewest the form of the earth." the reign of fishes began in the upper silurian, for in the rocks of this age, more especially in england, several species have been found. they occur, however, only in the newer beds of this formation, and are not of large size, nor very abundant. it is to be observed that, in so far as the fragments discovered can be interpreted, they indicate the existence already of two distinct types of fishes, the ganoids, or gar-fishes, protected with bony plates and scales, and the placoids, or shark-like fishes; and that in the existing world these fishes are regarded as occupying a high place in their class. further, these two groups of fishes are those which throughout a large portion of geological time continue to prevail to the exclusion of other types, the ordinary bony fishes having been introduced only in comparatively recent periods. with the devonian, however, there comes a vast increase to the finny armies; and so characteristic are these that the devonian has been called the age of fishes _par excellence_, and we must try, with the help of our illustration, to paint these old inhabitants of the waters as distinctly as we can. among the most ancient and curious of these fishes are those singular forms covered with broad plates, of which the _pteraspis_ of the upper silurian is the herald, and which are represented in the lower devonian by several distinct genera. of these, one of the most curious is the _cephalaspis_, or buckler-head, distinguished by its broad flat head, rounded in front and prolonged at the sides into two great spines, which project far beyond the sides of the comparatively slender body. this fish, it may be mentioned, is the type of a family highly characteristic of the lower devonian, as well as of the upper silurian, and all of which are provided with large plate-like cephalic coverings, sometimes with a long snout in front, and, in so far as is known, a comparatively weak body and tail. they were all probably ground-living creatures, feeding on worms and shell-fishes, and "rooting" for these in the mud, or burrowing therein for their safety. in these respects they have a most curious analogy to the trilobites, which in habits they must have greatly resembled, though belonging by their structure to an entirely different and much higher class. so close is this resemblance, that their head-shields used to be mistaken for those of trilobites. the case is one of those curious analogies which often occur in nature, and which must always be distinguished from the true affinities which rest on structural resemblances. another group of small fishes, likewise cuirassed in bony armour of plates, may be represented by the _pterichthys_, with its two strong bony fins at the sides, which may have served for swimming, but probably also for defence, and for creeping on or shovelling up the mud at the bottom of the sea. but, besides the ganoids which were armed in plated cuirasses, there were others, active and voracious, clad in shining enamelled scales, like the bony pikes of the american rivers and the _polypterus_ of the nile. some of these, like the _diplacanthus_, or "double-spine" were of small size, and chiefly remarkable for their sharp defensive bony spines. others, like _holoptychius_ (wrinkled-scale) and _osteolepis_ (bone-scale), were strongly built, and sometimes of great size. one russian species of _asterolepis_ (star-scale) is supposed to have been twenty feet in length, and furnished with strong and trenchant teeth in two rows. these great fishes afford a good reason for the spines and armour-plates of the contemporary trilobites and smaller fishes. just as man has been endeavouring to invent armour impenetrable to shot, for soldiers and for ships, and, on the other hand, shot and shells that can penetrate any armoury so nature has always presented the spectacle of the most perfect defensive apparatus matched with the most perfect weapons for destruction. in the class of fishes, no age of the world is more eminent in these respects then the devonian.[m] in addition to these fishes, there were others, represented principally by their strong bony spines, which must have been allied to some of the families of modern sharks, most of them, however, probably to that comparatively harmless tribe which, furnished with flat teeth, prey upon shell-fishes. there are other fishes difficult to place in our systems of classification; and among these an eminent example is the huge _dinichthys_ of newberry, from the hamilton group of ohio. the head of this creature is more then three feet long and eighteen inches broad, with the bones extraordinarily strong and massive. in the upper jaw, in addition to strong teeth, there were in front two huge sabre-shaped tusks or incisors, each nearly a foot long; and corresponding to these in the massive lower jaw were two closely joined conical tusks, fitting between those of the upper jaw. no other fish presents so frightful an apparatus for destruction; and if, as is probable, this was attached to a powerful body, perhaps thirty feet in length, and capable of rapid motion through the water, we cannot imagine any creature so strong or so well armed as to cope with the mighty _dinichthys_. [m] many of these were discovered and successfully displayed and described by hugh miller, and are graphically portrayed in his celebrated work on the "old red sandstone," published in . the difference between the fishes of the devonian and those of the modern seas is well marked by the fact that, while the ordinary bony fishes now amount to probably , species, and the ganoid fishes to less then thirty, the finny tribes of the devonian are predominantly ganoids, and none of the ordinary type are known. to what is this related, with reference to conditions of existence? two explanations, different yet mutually connected, may be suggested. one is that armour was especially useful in the devonian as a means of defence from the larger predaceous species, and the gigantic crustaceans of the period. that this was the case may be inferred from the conditions of existence of some modern ganoids. the common bony pike of canada (_lepidosteus_), frequenting shallow and stagnant waters, seems to be especially exposed to injury from its enemies. consequently, while it is rare to find an ordinary fish showing any traces of wounds, a large proportion of the specimens of the bony pike which i have examined have scars on their scales, indicating injuries which they have experienced, and which possibly, to fishes not so well armed, might have proved fatal. again, in the modern amia, or mud-fish, in the bony pike and _polypterus_, there is an extremely large air-bladder, amply supplied with blood-vessels, and even divided into cells or chambers, and communicating with the mouth by an "air-duct." this organ is unquestionably in function a lung, and enables the animal to dispense in some degree with the use of its gills, which of course depend for their supply of vital air on the small quantity of oxygen dissolved in the water. hence, by the power of partially breathing air, these fishes can live in stagnant and badly aerated waters, where other fishes would perish. in the case of the _amia_, the grunting noises which it utters, its habit of frequenting the muddy creeks of swamps, and its possession of gill-cleaners, correspond with this view. it is possible that the devonian fishes possessed this semi-reptilian respiration; and if so, they would be better adapted then other fishes to live in water contaminated with organic matter in a state of decay, or in waters rich in carbonic acid or deficient in oxygen. possibly the palæozoic waters, as well as the palæozoic atmosphere, were less rich in pure oxygen then those of the present world; and it is certain that, in many of the beds in which the smaller devonian fishes abound, there was so much decaying vegetable matter as to make it probable that the water was unfit for the ordinary fishes. thus, though at first sight the possession of external armour and means to respire air, in the case of these peculiar fishes, may seem to have no direct connection with each other, their obvious correlation in some modern ganoids may have had its parallel on a more extensive scale among their ancient relatives. just as the modern gar-fish, by virtue of its lungs, can live in stagnant shallows and hunt frogs, but on that account needs strong armour to defend it against the foes that assail it in such places; so in the devonian the capacity to inhabit unaërated water and defensive plates and scales may have been alike necessary, especially to the feebler tribes of fishes. we shall find that in the succeeding carboniferous period there is equally good evidence of this. we have reserved little space for the devonian plants and insects; but we may notice both in a walk through a devonian forest, in which we may include the vegetation of the several subordinate periods into which this great era was divisible. the devonian woods were probably, like those of the succeeding carboniferous period, dense and dark, composed of but few species of plants, and these somewhat monotonous in appearance, and spreading out into broad swampy jungles, encroaching on the shallow bays and estuaries. landing on one of these flats, we may first cast our eyes over a wide expanse, covered with what at a distance we might regard as reeds or rushes. but on a near approach they appear very different; rising in slender, graceful stems, they fork again and again, and their thin branches are sparsely covered with minute needle-like leaves, while the young shoots curl over in graceful tresses, and the older are covered with little oval fruits, or spore-cases; for these plants are cryptogamous, or flowerless. this singular vegetation stretches for miles along the muddy flats, and rises to a height of two or three feet from a knotted mass of cylindrical roots or root-stocks, twining like snakes through and over the soil. this plant may, according as we are influenced by its fruit or structure, be regarded as allied to the modern club-mosses or the modern pill-worts. it is _psilophyton_, in every country one of the most characteristic plants of the period, though, when imperfectly preserved, often relegated by careless and unskilled observers to the all-engulfing group of fucoids. a little further inland we see a grove of graceful trees, forking like _psilophyton_, but of grander dimensions, and with the branches covered with linear leaves, and sometimes terminated by cones. these are _lepidodendra_, gigantic club-mosses, which were developed to still greater dimensions in the coal period. near these we may see a still more curious tree, more erect in its growth, with rounded and somewhat rigid leaves and cones of different form, and with huge cable-like roots, penetrating the mud, and pitted with the marks of long rootlets. this is _cyclostigma_, a plant near to the _lepidodendron_, but distinct, and peculiar to the devonian. some of its species attain to the dimensions of considerable trees; others are small and shrubby. another small tree, somewhat like the others, but with very long shaggy leaves, and its bark curiously marked with regular diamond-shaped scars, is the _leptophleum_. all these plants are probably allied to our modern club-mosses, which are, however, also represented by some low and creeping species cleaving to the ground. a little further, and we reach a dense clump of _sigillariæ_, with tall sparsely forking stems, and ribbed with ridges holding rows of leaf-scars a group of plants which we shall have further occasion to notice in the coal formation; and here is an extensive jungle of _calamites_, gigantic and overgrown mares'-tails, allies of the modern equisetums. [illustration: fig. .--vegetation of the devonian. to the left are _calamites_; next to these, _leptophleum_; in the centre are _lepidodendron_, _sigillaria_, and a pine. below are _psilophyton_, _cordaites_, ferns, and _asterophyllites_.] amidst these trees, every open glade is filled with delicate ferns of marvellous grace and beauty; and here and there a tree-fern rears its head, crowned with its spreading and graceful leaves, and its trunk clad with a shaggy mass of aërial roots--an old botanical device, used in these ancient times, as well as now, to strengthen and protect the stems of trees not fitted for lateral expansion. beyond this mass of vegetation, and rising on the slopes of the distant hills, we see great trees that look like pines. we cannot approach them more nearly; but here on the margin of a creek we see some drift-trunks, that have doubtless been carried down by a land flood. one of them is certainly a pine, in form and structure of its wood very like those now living in the southern hemisphere; it is a _dadoxylon_. another is different, its sides rough and gnarled, and marked with huge irregular ridges; its wood loose, porous, and stringy, more like the bark of modern pines, yet having rings of growth and a true bark of its own, and sending forth large branches and roots. it is the strange and mysterious _prototaxites_, one of the wonders of the devonian land, and whose leaves and fruits would be worth their weight in gold in our museums, could we only procure them. a solitary fragment further indicates that in the yet unpenetrated solitudes of the devonian forests there may be other trees more like our ordinary familiar friends of the modern woods; but of these we know as yet but little. what inhabitants have these forests? all that we yet know are a few large insects, relatives of our modern may-flies, flitting with broad veined wings over the stagnant waters in which their worm-like larvæ dwell, and one species at least assuming one of the properties of the grasshopper tribe, and enlivening the otherwise silent groves with a cricket-like chirp, the oldest music of living things that geology as yet reveals to us; and this, not by the hearing of the sound itself, but by the poor remains of the instrument attached to a remnant of a wing from the devonian shales of new brunswick. a remarkable illustration of the abundance of certain plants in the devonian, and also of the slow and gradual accumulation of some of its beds, is furnished by layers of fossil spore-cases, or the minute sacs which contain the microscopic germs of club-mosses and similar plants. in the american forests, in spring, the yellow pollen-grains of spruces and pines sometimes drift away in such quantities in the breeze that they fall in dense showers, popularly called showers of sulphur; and this vegetable sulphur, falling in lakes and ponds, is drifted to the shore in great sheets and swathes. the same thing appears to have occurred in the devonian, not with the pollen of flowering plants, but with the similar light spores and spore-cases of species of lepidodendron and allied trees. in a bed of shale, at kettle point, lake huron, from to feet thick, not only are the surfaces of the beds dotted over with minute round spore-cases, but, on making a section for the microscope, the substance of each layer is seen to be filled with them; and still more minute bodies, probably the escaped spores, are seen to fill up their interstices. the quantity of these minute bodies is so great that the shale is combustible, and burns with much flame. a bed of this nature must have been formed in shallow and still water, on the margin of an extensive jungle or forest; and as the spore-cases are similar to those of the lepidodendra of the coal-measures, the trees were probably of this kind. year after year, as the spores became ripe, they were wafted away, and fell in vast quantities into the water, to be mixed with the fine mud there accumulating. when we come to the coal period, we shall see that such beds of spore-cases occur there also, and that they have even been supposed to be mainly instrumental in the accumulation of certain beds of coal. their importance in this respect may have been exaggerated, but the fact of their occurrence in immense quantities in certain coals and shales is indisputable. this is but a slender sketch of the devonian forests: but we shall find many of the same forms of plants in the carboniferous period which succeeds. with one thought we may close. we are prone to ask for reasons and uses for things, but sometimes we cannot be satisfied. of what use were the devonian forests? they did not, like those of the coal formation, accumulate rich beds of coal for the use of man. except possibly a few insects, we know no animals that subsisted on their produce, nor was there any rational being to admire their beauty. their use, except as helping us in these last days to complete the order of the vegetable kingdom as it has existed in geological time, is a mystery. we can but fall back on that ascription of praise to him "who liveth for ever and ever," on the part of the heavenly elders who cast down their crowns before the throne and say, "thou art worthy, lord, to receive the glory, and the honour, and the might; because thou didst create all things, and by reason of _thy will_ they are and were created." chapter vi. the carboniferous age. that age of the world's history which, from its richness in accumulations of vegetable matter destined to be converted into coal, has been named the carboniferous, is in relation to living beings the most complete and noble of the palæozoic periods. in it those varied arrangements of land and water which had been increasing in perfection in the previous periods, attained to their highest development. in it the forms of animal and plant life that had been becoming more numerous and varied from the eozoic onward, culminated. the permian which succeeded was but the decadence of the carboniferous, preparatory to the introduction of a new order of things. thus the carboniferous was to the previous periods what the modern is to the preceding tertiary and mesozoic ages the summation and completion of them all, and the embodiment of their highest excellence. if the world's history had closed with the carboniferous, a naturalist, knowing nothing further, would have been obliged to admit that it had already fulfilled all the promise of its earlier years. it is important to remember this, since we shall find ourselves entering on an entirely new scene in the mesozoic period, and since this character of the carboniferous, as well as its varied conditions and products, may excuse us for dwelling on it a little longer then on the others, on the other hand, the immense economic importance of the coal formation, and the interesting points connected with it, have made the carboniferous more familiar to general readers then most other geological periods, so that we may select points less common and well-known for illustration. popular expositions of geology are, however, generally so one-sided and so distorted by the prevalent straining after effect, that the true aspect of this age is perhaps not much better known then that of others less frequently described. let us first consider the carboniferous geography of the northern hemisphere; and in doing so we may begin with a fact concerning the preceding age. one of the most remarkable features of the newer devonian is the immense quantity of red rocks, particularly red sandstones, contained in it. red sandstones, it is true, occur in older formations, but comparatively rarely; their great head-quarters, both in europe and america, in so far as the palæozoic is concerned, are in the upper devonian. now red sandstone is an infallible mark of rapid deposition, and therefore of active physical change. if we examine the grains of sand in a red sandstone, we shall find that they are stained or coated, externally, with the peroxide of iron, or iron rust; and that this coating, with perhaps a portion of the same substance in the intervening cement, is the cause of the colour. in finer sandstones and red clays the same condition exists, though less distinctly perceptible. consequently, if red sands and clays are long abraded or scoured in water, or are subjected to any chemical agent capable of dissolving the iron, they cease to be red, and resume their natural grey or white colour. now in nature, in addition to mechanical abrasion, there is a chemical cause most potent in bleaching red rocks, namely, the presence of vegetable or animal matter in a state of decay. without entering into chemical details, we may content ourselves with the fact that organic matter decaying in contact with peroxide of iron tends to take oxygen from it, and then to dissolve it in the state of protoxide, while the oxygen set free aids the decay. carrying this fact with us, we may next affirm that iron is so plentiful in the crust of the earth that nearly all sands and clays when first produced from the weathering of rocks are stained with it, and that when this weathering takes place in the air, the iron is always in the state of peroxide. more especially does this apply to the greater number of igneous or volcanic rocks, which nearly always weather brown or red. now premising that the original condition of sediment is that of being reddened with iron, and that it may lose this by abrasion, or by the action of organic matter, it follows that when sand has been produced by decay of rocks in the air, and when it is rapidly washed into the sea and deposited there, red beds will result. for instance, in the bay of fundy, whose rapid tides cut away the red rocks of its shores and deposit their materials quickly, red mud and sand constitute the modern deposit. on the other hand, when the red band and mud are long washed about, their red matter may disappear; and when the deposition is slow and accompanied with the presence of organic matter, the red colour is not only removed, but is replaced by the dark tints due to carbon. thus, in the gulf of st. lawrence, where red rocks similar to those of the bay of fundy are being more slowly wasted, and deposited in the presence of sea-weeds and other vegetable substances, the resulting sands and clays are white and grey or blackened in colour. an intermediate condition is sometimes observed, in which red beds are stained with grey spots and lines, where sea-weeds or land-plants have rested on them. i have specimens of devonian red shale with the forms of fern leaves, the substance of which has entirely perished, traced most delicately upon them in greenish marks. it follows from these facts that extensive and thick deposits of red beds evidence sub-aërial decay of rocks, followed by comparatively rapid deposition in water, and that such red rocks will usually contain few fossils, not only because of their rapid deposition, but because the few organic fragments deposited with them will probably have been destroyed by the chemical action of the superabundant oxide of iron, which, so to speak, "iron-moulds" them, just as stains of iron eat holes out of linen. now when sir roderick murchison tells us of , feet in thickness of red iron-stained rocks in the old red sandstone of england, we can see in this the evidence of rapid aqueous deposition, going on for a very long time, and baring vast areas of former land surface. consequently we have proof of changes of level and immense and rapid denudation--a conclusion further confirmed by the apparent unconformity of different members of the series to each other in some parts of the british islands, the lower beds having been tilted up before the newer were deposited. such was the state of affairs very generally at the close of the devonian, and it appears to have been accompanied with some degree of subsidence of the land, succeeded by re-elevation at the beginning of the carboniferous, when many and perhaps large islands and chains of islands were raised out of the sea, along whose margins there were extensive volcanic eruptions, evidenced by the dykes of trap traversing the devonian, and the beds of old lava interstratified in the lower part of the carboniferous, where also the occurrence of thick beds of conglomerate or pebble-rock indicates the tempestuous action of the sea. but a careful study of the lower carboniferous beds, where their margins rest upon the islands of older rocks, shows great varieties in these old shores. in some places there were shingly beaches; in others, extensive sand-banks; in others, swampy flats clothed with vegetation, and sometimes bearing peaty beds, still preserved as small seams of coal. the bays and creeks swarmed with, fishes. a few sluggish reptiles crept along the muddy or sandy shores, and out sea-ward were great banks and reefs of coral and shells in the clear blue sea. the whole aspect of nature, taken in a general view, in the older carboniferous period, must have much resembled that at present seen among the islands of the southern hemisphere. and the plants and animals, though different, were more like those of the modern south pacific then any others now living. as the age wore on, the continents were slowly lifted out of the water, and the great continental plateaus were changed from coral seas into swampy flats or low uplands, studded in many places with shallow lakes, and penetrated with numerous creeks and sluggish streams. in the eastern continent these land surfaces prevailed extensively, more especially in the west; and in america they spread both eastward and westward from the appalachian ridge, until only a long north and south mediterranean, running parallel to the rocky mountains, remained of the former wide internal ocean. on this new and low land, comparable with the "sylvas" of the south american continent, flourished the wondrous vegetation of the coal period, and were introduced the new land animals, whose presence distinguishes the close of the palæozoic. after a vast lapse of time, in which only slow and gradual subsidence occurred, a more rapid settlement of the continental areas brought the greater part of the once fertile plains of the coal formation again under the waters; and shifting sand-banks and muddy tides engulfed and buried the remains of the old forests, and heaped on them a mass of sediment, which, like the weights of a botanical press, flattened and compressed the vegetable _débris_ preserved in the leaves of the coal formation strata. then came on that strange and terrible permian period, which, like the more modern boulder-formation, marked the death of one age and the birth of another. the succession just sketched is the normal one; but the terms in which it has been described show that it cannot be universal. there are many places in which the whole thickness of the carboniferous is filled with fossils of the land, and of estuaries and creeks. there are places, on the other hand, where the deep sea appears to have continued during the whole period. in america this is seen on the grandest scale in the absence of the marine members along the western slopes of the appalachians, and the almost exclusive prevalence of marine beds in the far west, where the great carboniferous mediterranean of america spread itself, and continued uninterruptedly into the succeeding permian period. in our survey of the carboniferous age, though there are peculiarities in the life of its older, middle, and newer divisions, we may take the great coal measures of the middle portion as the type of the land life of the period, and the great limestones of the lower portion as that of the marine life; and as the former is in this period by far the most important, we may begin with it. before doing so, however, to prevent misapprehension, it is necessary to remind the reader that the flora of the middle coal period is but one of a succession of related floras that reach from the upper silurian to the permian. the meagre flora of club-mosses and their allies in the upper silurian and lower devonian was succeeded by a comparatively rich and varied assemblage of plants in the middle devonian. the upper devonian was a period of decadence, and in the lower carboniferous we have another feeble beginning, presenting features somewhat different from those of the upper devonian. this was the time of the culm of germany, the tweedian formation of the north of england and south of scotland, and the lower coal formation of nova scotia. it was a period eminently rich in lepidodendra. it was followed by the magnificent flora of the middle coal formation, and then there was a time of decadence in the upper coal formation and only a slight revival in the permian. in the present condition of our civilization, coal is the most important product which the bowels of the earth afford to man. and though there are productive beds of coal in most of the later geological formations, down to the peats of the modern period, which are only unconsolidated coals, yet the coal of the carboniferous age is the earliest valuable coal in point of time, and by far the most important in point of quantity. mineral coal may be defined to be vegetable matter which has been buried in the strata of the earth's crust, and there subjected to certain chemical and mechanical changes. the proof of its vegetable origin will grow upon us as we proceed. the chemical changes which it has undergone are not very material. wood or bark, taken as an example of ordinary vegetable matter, consists of carbon or charcoal, with the gases hydrogen and oxygen. coal has merely parted with a portion of these ingredients in the course of a slow and imperfect putrefaction, so that it comes to have much less oxygen and considerably less hydrogen then wood, and it has been blackened by the disengagement of a quantity of free carbon. the more bituminous flaming coals have a larger amount of residual hydrogen. in the anthracite coals the process of carbonisation has proceeded further, and little remains but charcoal in a dense and compact form. in cannel coals, and in certain bituminous shales, on the contrary, the process seems to have taken place entirely under water, by which putrefaction has been modified, so that a larger proportion then usual of hydrogen has been retained. the mechanical change which the coal has experienced consists in the flattening and hardening effect of the immense pressure of thousands of feet of superincumbent rock, which has crashed together the cell-walls of the vegetable matter, and reduced what was originally a pulpy mass of cellular tissue to the condition of a hard laminated rock. to understand this, perhaps the simplest way is to compare under the microscope a transverse section of recent pine-wood with a similar section of a pine trunk compressed into brown coal or jet. in the one the tissue appears as a series of meshes with thin woody walls and comparatively wide cavities for the transmission of the sap. in the other the walls of the cells have been forced into direct contact, and in some cases have altogether lost their separate forms, and have been consolidated into a perfectly compact structureless mass. with regard to its mode of occurrence, coal is found in beds ranging in vertical thickness from less then an inch to more then thirty feet, and of wide horizontal extent. many such beds usually occur in the thickness of the coal formation, or "coal measures," as the miners call it, separated from each other by beds of sandstone and compressed clay or shale. very often the coal occurs in groups of several beds, somewhat close to each other and separated from other groups by "barren measures" of considerable thickness. in examining a bed of coal, where it is exposed in a cutting or shore cliff, we nearly always find that the bed below it, or the "underclay," as it is termed by miners, is a sort of fossil soil, filled with roots and rootlets. on this rests the coal, which, when we examine it closely, is found to consist of successive thin layers of hard coal of different qualities as to lustre and purity, and with intervening laminae of a dusty fibrous substance, like charcoal, called "mother coal" by miners, and sometimes mineral charcoal. thin partings of dark shale also occur, and these usually present marks and impressions of the stems and leaves of plants. above the coal is its "roof" of hardened clay or sandstone, and this generally holds great quantities of remains of plants, and sometimes large stumps of trees with their bark converted into coal, and the hollow once occupied with wood filled with sandstone, while their roots spread over the surface of the coal. such fossil forests of erect stumps are also found at various levels in the coal measures, resting directly on under-clays without any coals. a bed of coal would thus appear to be a fossil bog or swamp. this much being premised about the general nature of the sooty blocks which fill our coal-scuttles, we may now transport ourselves into the forests and bogs of the coal formation, and make acquaintance with this old vegetation, while it still waved its foliage in the breeze and drank in the sunshine and showers. we are in the midst of one of those great low plains formed by the elevation of the former sea bed. the sun pours down its fervent rays upon us, and the atmosphere, being loaded with vapour, and probably more rich in carbonic acid then that of the present world, the heat is as it were accumulated and kept near the surface, producing a close and stifling atmosphere like that of a tropical swamp. this damp and oppressive air is, however, most favourable to the growth of the strange and grotesque trees which tower over our heads, and to the millions of delicate ferns and club-mosses, not unlike those of our modern woods, which carpet the ground. around us for hundreds of miles spreads a dense and monotonous forest, with here and there open spaces occupied by ponds and sluggish streams, whose edges are bordered with immense savannahs of reed-like plants, springing from the wet and boggy soil. everything bespeaks a rank exuberance of vegetable growth; and if we were to dig downward into the soil, we should find a thick bed of vegetable mould evidencing the prevalence of such conditions for ages. but the time will come when this immense flat will meet with the fate which in modern times befell a large district at the mouth of the indus. quietly, or with earthquake shocks, it will sink under the waters; fishes and mollusks will swarm where trees grew, beds of sand and mud will be deposited by the water, inclosing and preserving the remains of the vegetation, and in some places surrounding and imbedding the still erect trunks of trees. many feet of such deposits may be formed, and our forest surface, with its rich bed of vegetable mould, has been covered up and is in process of transformation into coal; while in course of time the shallow waters being filled up with deposit, or a slight re-elevation occurring, a new forest exactly like the last will flourish on the same spot. such changes would be far beyond the compass of the life even of a methuselah; but had we lived in the coal period, we might have seen all stages of these processes contemporaneously in different parts of either of the great continents. but let us consider the actual forms of vegetation presented to us in the coal period, as we can restore them from the fragments preserved to us in the beds of sandstone and shale, and as we would have seen them in our imaginary excursion through the carboniferous forests. to do this we must first glance slightly at the great subdivisions of modern plants, which we may arrange in such a way as to give an easy means for comparison of the aspects of the vegetable kingdom in ancient and modern times. in doing this i shall avail myself of an extract from a previous publication of my own on this subject. "the modern flora of the earth admits of a grand twofold division into the _phænogamous_, or flowering and seed-bearing plants, and the _cryptogamous_, or flowerless and spore-bearing plants. in the former series, we have, first, those higher plants which start in life with two seed-leaves, and have stems with distinct bark, wood, and pith--the _exogens_; secondly, those similar plants which begin life with one seed-leaf only, and have no distinction of bark, wood, and pith, in the stem--the _endogens_; and, thirdly, a peculiar group starting with two or several seed-leaves, and having a stem with bark, wood, and pith, but with very imperfect flowers, and wood of much simpler structure then either of the others--the _gymnosperms_. to the first of these groups or classes belong most of the ordinary trees of temperate climates. to the second belong the palms and allied trees found in tropical climates. to the third belong the pines and cycads. in the second or cryptogamous series we have also three classes,--( .) the _acrogens_, or ferns and club-mosses, with stems having true vessels marked on the sides with cross-bars--the scalariform vessels. ( .) the _anophytes_, or mosses and their allies, with stems and leaves, but no vessels. ( .) the _thallophytes_, or lichens, fungi, sea-weeds, etc., without true stems and leaves. "in the existing climates of the earth we find these classes of plants variously distributed as to relative numbers. in some, pines predominate. in others, palms and tree-ferns form a considerable part of the forest vegetation. in others, the ordinary exogenous trees predominate, almost to the exclusion of others. in some arctic and alpine regions, mosses and lichens prevail. in the coal period we have found none of the higher exogens, though one species is known in the devonian, and only a few obscure indications of the presence of endogens; but gymnosperms abound, and are highly characteristic. on the other hand, we have no mosses or lichens, and very few algæ, but a great number of ferns and lycopodiaceæ or club-mosses. thus the coal formation period is botanically a meeting-place of the lower phænogams and the higher cryptogams, and presents many forms which, when imperfectly known, have puzzled botanists in regard to their position in one or other series. in the present world, the flora most akin to that of the coal period is that of moist and warm islands in the southern hemisphere. it is not properly a tropical flora, nor is it the flora of a cold region, but rather indicative of a moist and equable climate. in accordance with this is the fact that the equable but not warm climate of the southern hemisphere at present (which is owing principally to its small extent of land) enables sub-tropical plants to extend into high latitudes. in the coal period this uniformity was evidently still more marked, since we find similar plants extending from regions within the arctic circle to others near to the tropics. still we must bear in mind that we may often be mistaken in reasoning as to the temperature required by extinct species of plants differing from those now in existence. further, we must not assume that the climatal conditions of the northern hemisphere were in the coal period at all similar to those which now prevail. as sir charles lyell has argued, a less amount of land in the higher latitudes would greatly modify climates, and there is every reason to believe that in the coal period there was less land then now. it has been shown by tyndall that a very small additional amount of carbonic acid in the atmosphere would, by obstructing the radiation of heat from the earth, produce almost the effect of a glass roof or conservatory, extending over the whole world. there is much in the structure of the leaves of the coal plants, as well as in the vast amount of carbon which they accumulated in the form of coal, and the characteristics of the animal life of the period, to indicate, on independent grounds, that the carboniferous atmosphere differed from that of the present world in this way, or in the presence of more carbonic acid--a substance now existing in the very minute proportion of one-thousandth of the whole by weight, a quantity adapted to the present requirements of vegetable and animal life, but probably not to those of the coal period." returning from this digression to the forests of the coal period, we may first notice that which is the most conspicuous and abundant tree in the swampy levels--the sigillaria or seal-tree, so called from the stamp-like marks left by the fall of its leaves--a plant which has caused much discussion as to its affinities. some regard it as a gymnosperm, others as a cryptogam. most probably we have under this name trees allied in part to both groups, and which, when better known, may bridge over the interval between them. these trees present tall pillar-like trunks, often ribbed vertically with raised bands, and marked with rows of scars left by the fallen leaves. they are sometimes branchless, or divide at top into a few thick limbs, covered with long rigid grass-like foliage. on their branches they bear long slender spikes of fruit, and we may conjecture that quantities of nut-like seeds scattered over the ground around their trunks are their produce. if we approach one of these trees closely, more especially a young specimen not yet furrowed by age, we are amazed to observe the accurate regularity and curious forms of the leaf-scars, and the regular ribbing, so very different from that of our ordinary forest trees. if we cut into its stem, we are still further astonished at its singular structure. externally it has a firm and hard rind. within this is a great thickness of soft cellular inner bark, traversed by large bundles of tough fibres. in the centre is a core or axis of woody matter very slender in proportion to the thickness of the trunk, and still further reduced in strength by a large cellular pith. thus a great stem four or five feet in diameter is little else then a mass of cellular tissue, altogether unfit to form a mast or beam, but excellently adapted, when flattened and carbonised, to blaze upon our winter hearth as a flake of coal. the roots of these trees were perhaps more singular then their stems; spreading widely in the soft soil by regular bifurcation, they ran out in long snake-like cords, studded all over with thick cylindrical rootlets, which spread from them in every direction. they resembled in form, and probably in function, those cable-like root-stocks of the pond-lilies which run through the slime of lakes, but the structure of the rootlets was precisely that of those of some modern cycads. it was long before these singular roots were known to belong to a tree. they were supposed to be the branches of some creeping aquatic plant, and botanists objected to the idea of their being roots; but at length their connection with sigillaria was observed simultaneously by mr. binney, in lancashire, and by mr. richard brown, in cape breton, and it has been confirmed by many subsequently observed facts. this connection, when once established, further explained the reason of the almost universal occurrence of stigmaria, as these roots were called, under the coal beds; while trunks of the same plants were the most abundant fossils of their partings and roofs. the growth of successive generations of sigillariæ was, in fact, found to be the principal cause of the accumulation of a bed of coal. two species form the central figures in our illustration. [illustration: fig. .--group of carboniferous plants, restored from actual specimens. (_a_) calamites (type of _c. suckovii_). (_b_) lepidofloios, or ulodendron. (_c_) sigillaria (type of _s. reniformis_). (_d_) (type of _s. elegans_). (_e_) lepidodendron (type of _l. corrugatum_). (_f_) megaphyton (type of _m. magnificum_). (_g_) cordaites, or pychnophyllum (type of _c. borassifolia_).] along with the trees last mentioned, we observe others of a more graceful and branching form, the successors of those lepidodendra already noticed in the devonian, and which still abound in the carboniferous, and attain to larger dimensions then their older relations, though they are certainly more abundant and characteristic in the lower portions of the carboniferous. relatives, as already stated, of our modern club-mosses, now represented only by comparatively insignificant species, they constitute the culmination of that type, which thus had attained its acme very long ago, though it still continues to exist under depauperated forms. they all branched by bifurcation, sometimes into the most graceful and delicate sprays. they had narrow slender leaves, placed in close spirals on the branches. they bore their spores in scaly cones. their roots were similar to stigmaria in general appearance, though differing in details. in the coal period there were several generic forms of these plants, all attaining to the dimensions of trees. like the sigillariæ, they contributed to the materials of the coal; and one mode of this has recently attracted some attention. it is the accumulation of their spores and spore-cases already referred to in speaking of the devonian, and which was in the carboniferous so considerable as to constitute an important feature locally in some beds of coal. a similar modern accumulation of spore-cases of tree-ferns occurs in tasmania; but both in the modern and the carboniferous, such beds are exceptional; though wherever spore-cases exist as a considerable constituent of coal, from their composition they give to it a highly bituminous character, an effect, however, which is equally produced by the hard scales supporting the spores, and by the outer epidermal tissues of plants when these predominate in the coal, more especially by the thick corky outer bark of sigillaria. in short, the corky substance of bark and similar vegetable tissues, from its highly carbonaceous character, its indestructibility, and its difficult permeability by water carrying mineral matter in solution, is the best of all materials for the production of coal; and the microscope shows that of this the principal part of the coal is actually composed. in the wide, open forest glades, tree-ferns almost precisely similar to those of the modern tropics reared their leafy crowns. but among them was one peculiar type, in which the fronds were borne in pairs on opposite sides of the stem, leaving when they fell two rows of large horseshoe-shaped scars marking the sides of the trunk. botanists, who have been puzzled with these plants almost as much as with the stigmaria, have supposed these scars to be marks of branches, of cones, and even of aërial roots; but specimens in my collection prove conclusively that the stem of this genus was a great caudex made up of the bases of two rows of huge leaves cemented together probably by intervening cellular tissue. as in the devonian and in modern times, the stems of the tree-ferns of the carboniferous strengthened themselves by immense bundles of cord-like aërial roots, which look like enormous fossil brooms, and are known under the name psaronius. we have only time to glance at the vast brakes of tall calamites which fringe the sigillaria woods, and stretch far sea-ward over tidal flats. they were allied to modern mares' tails or equisetums, but were of gigantic size, and much more woody structure of stem. the calamites grew on wet mud and sand-flats, and also in swamps; and they appear to have been especially adapted to take root in and clothe and mat together soft sludgy material recently deposited or in process of deposition. when the seed or spore of a calamite had taken root, it probably produced a little low whorl of leaves surrounding one small joint, from which another and another, widening in size, arose, producing a cylindrical stem, tapering to a point below. to strengthen the unstable base, the lower joints, especially if the mud had been accumulating around the plant, shot out long roots instead of leaves, while secondary stems grew out of the sides at the surface of the soil, and in time there was a stool of calamites, with tufts of long roots stretching downwards, like an immense brush, into the mud. when calamites thus grew on inundated flats, they would, by causing the water to stagnate, promote the elevation of the surface by new deposits, so that their stems gradually became buried; but this only favoured their growth, for they continually pushed out new stems, while the old buried ones shot out bundles of roots instead of regular whorls of leaves. the calamites, growing in vast fields along the margins of the sigillaria forests, must have greatly protected these from the effects of inundations, and by collecting the mud brought down by streams in times of flood, must have done much to prevent the intrusion of earthy deposits among the vegetable matter. their chief office, therefore, as coal-producers, seems to have been to form for the sigillaria forests those reedy fringes which, when inundations took place, would exclude mud, and prevent that mixture of earthy matter in the coal which would have rendered it too impure for use. quantities of fragments of their stems can, however, be detected by the microscope in most coals. the modern mares' tails have thin-walled hollow stems, and some of the gigantic calamites of the coal resembled them in this. but others, to which the name _calamodendron_, or reed-tree, has been given, had stems with thick woody walls of a remarkable structure, which, while similar in plan to that of the mares' tails, was much more perfect in its development. professor williamson has shown that there were forms intervening between these extremes; and thus in the calamites and calamodendrons we have another example of the exaltation in ancient times of a type now of humble structure; or, in other words, of a comprehensive type, low in the modern world, but in older periods taking to itself by anticipation the properties afterward confined to higher forms. the gigantic club-mosses of the coal period constitute a similar example, and it is very curious that both of these types have been degraded in the modern world, though retaining precisely their general aspect, while the tree-ferns contemporary with them in the palæozoic still survive in all their original grandeur. barely in the swampy flats, perhaps more frequently in the uplands, grew great pines of several kinds; trees capable of doing as good service for planks and beams as many of their modern successors, but which lived before their time, and do not appear even to have aided much in the formation of coal. these pines of the coal-period seem to have closely resembled some species still living in the southern hemisphere; and, like the ferns, they present to us a vegetable type which has endured through vast periods of time almost unchanged. indeed, in the middle devonian we have pines almost as closely resembling those of the modern world as do those of the coal period. it is in accordance with this long duration of the ferns and pines, that they are plants now of world-wide distribution--suited to all climates and stations. capacity to exist under varied conditions is near akin to capacity to survive cosmical changes. a botanist in the strange and monstrous woods which we have tried to describe, would probably have found many curious things among the smaller herbaceous plants, and might have gathered several precursors of the modern exogens and endogens which have not been preserved to us as fossils, or are known only as obscure fragments. but incomplete though our picture necessarily is, and obscured by the dust of time, it may serve in some degree to render green to our eyes those truly primeval forests which treasured up for our long winter nights the palæozoic sunshine, and established for us those storehouses of heat-giving material which work our engines and propel our ships and carriages. truly they lived not in vain, both as realizing for us a type of vegetation which otherwise we could not have imagined, and as preparing the most important of all the substrata of our modern arts and manufactures. in this last regard even the vegetable waste of the old coal swamps was most precious to us, as the means of producing the clay iron ores of the coal measures. i may close this notice of the carboniferous forests with a suggestive extract from a paper by professor huxley in the _contemporary review_:-- "nature is never in a hurry, and seems to have had always before her eyes the adage, 'keep a thing long enough, and you will find a use for it.' she has kept her beds of coal for millions of years without being able to find much use for them; she has sent them down beneath the sea, and the sea-beasts could make nothing of them: she has raised them up into dry land and laid the black veins bare, and still for ages and ages there was no living thing on the face of the earth that could see any sort of value in them; and it was only the other day, so to speak, that she turned a new creature oat of her workshop, who by degrees acquired sufficient wits to make a fire, and then to discover that the black rock would burn. "i suppose that nineteen hundred years ago, when julius cæsar was good enough to deal with britain as we have dealt with new zealand, the primeval briton, blue with cold and woad, may have known that the strange black stone, of which he found lumps here and there in his wanderings, would burn, and so help to warm his body and cook his food. saxon, dane, and norman swarmed into the land. the english people grew into a powerful nation, and nature still waited for a return for the capital she had invested in the ancient club-mosses. the eighteenth century arrived, and with it james watt. the brain of that man was the spore out of which was developed the steam-engine, and all the prodigious trees and branches of modern industry which have grown out of this. but coal is as much an essential condition of this growth and development as carbonic acid is for that of a club-moss. wanting the coal, we could not have smelted the iron needed to make our engines, nor have worked our engines when we had got them. but take away the engines, and the great towns of yorkshire and lancashire vanish like a dream. manufactures give place to agriculture and pasture, and not ten men could live where now ten thousand are amply supported. "thus all this abundant wealth of money and of vivid life is nature's investment in club-mosses and the like so long ago. but what becomes of the coal which is burnt in yielding the interest? heat comes out of it, light comes out of it, and if we could gather together all that goes up the chimney and all that remains in the grate of a thoroughly-burnt coal fire, we should find ourselves in possession of a quantity of carbonic acid, water, ammonia, and mineral matters, exactly equal in weight to the coal. but these are the very matters with which nature supplied the club-moss which made the coal. she is paid back principal and interest at the same time; and she straightway invests the carbonic acid, the water, and the ammonia in new forms of life, feeding with them the plants that now live. thrifty nature! surely no prodigal, but most notable of housekeepers!" all this is true and admirably put. its one weak point is the poetical personification of nature as an efficient planner of the whole. such an imaginary goddess is a mere superstition, unknown alike to science and theology. surely it is more rational to hold that the mind which can utilize the coal and understand the manner of its formation, is itself made in the image and likeness of the supreme creative spirit, in whom we live and move and have our being, who knows the end from the beginning, whose power is the origin of natural forces, whose wisdom is the source of laws and correlations of laws, and whose great plan is apparent alike in the order of nature of the palæozoic world and of the modern world, as well as in the relation of these to each other. in the carboniferous, as in the devonian age, insects existed, and in greater numbers. the winged insects of the period, so far as known, belong to three of the nine or ten orders into which modern insects are usually divided. conspicuous among them are representatives of our well-known domestic pests the cockroaches, which thus belong geologically to a very old family. the carboniferous roaches had not the advantage of haunting our larders, but they had abundance of vegetable food in the rank forests of their time, and no doubt lived much as the numerous wild out-of-door species of this family now do. it is, however, a curious fact that a group of insects created so long ago, should prove themselves capable of the kind of domestication to which these creatures attain in our modern days; and that, had we lived even so far back as the coal period, we might have been liable to the attacks of this particular kind of pest. another group, represented by many species in the coal forests, was that of the may-flies and shad-flies, or ephemeras, which spend their earlier days under water, feeding on vegetable matter, and affording food to many fresh-water fishes--a use which they no doubt served in the coal period also. some of them were giants in their way, being probably seven inches in expanse of wing, and their larvæ must have been choice morsels to the ganoid fishes, and would have afforded abundant bait had there been anglers in those days. another group of insects was that of the weevils, a family of beetles, whose grubs must have found plenty of nuts and fruits to devour, without attracting the wrathful attentions of any gardener or orchardist. a curious and exceptional little group of creatures in the present world is that of the galley-worms or millipedes; wingless, many-jointed, and many-footed crawlers, resembling worms, but more allied to insects. these animals seem to have swarmed in the coal forests, and perhaps attained their maximum numbers and importance in this period, though they still remain, a relic of an ancient comprehensive type. i have myself found specimens referred by mr. scudder, a most competent entomologist, to two genera and five species, in a few decayed fossil stumps in nova scotia, and several others have been discovered in other parts of the world. it is not wonderful that animals like these, feeding on decayed vegetable matter, should have flourished in the luxuriant sigillaria swamps. a few species of scorpions and spiders, very like those of the modern world, have been found in the coal measures, both in europe and america; so that while we know of no enemy of the devonian insects except the fishes, we know in addition to these in the carboniferous the spiders and their allies, and the smaller reptiles or batrachians to be noticed in the sequel. with reference to the latter, it is a curious fact that one of the first fragments of a winged insect found in the coal-fields of america was a part of a head and some other remains contained in the coprolites or excrementitious matter of one of the smaller fossil reptiles. it is perhaps equally interesting that this head shows one of the compound facetted eyes as perfectly developed as those of any modern neuropter, a group of insects remarkable even in the present world for their large and complex organs of vision. we may pause here to note that, just as in the primordial we already have the trilobites presenting all the modifications of which the type is susceptible, so in the carboniferous we have in the case of the terrestrial articulates a similar fact--highly specialised forms like the beetles, the spiders, and the scorpions, already existing along with comprehensive forms like the millipedes. let us formulate the law of creation which the primordial trilobites, the devonian fishes, and the carboniferous club-mosses and insects have taught us: it is, that every new type rapidly attains its maximum of development in magnitude and variety of forms, and then remains stationary, or even retrogrades, in subsequent ages. we may connect this with other laws in the sequel. in the coal measures we also meet, for the first time in our ascending progress, the land snails so familiar now in every part of the world, and which are represented by two little species found in the coal formation of nova scotia. the figures of these must speak for themselves; but the fact of their occurrence here and the mode of their preservation require some detailed mention. the great province of the mollusks we have carried with us since we met with the lingulæ in the primordial, but all its members have been aquatic, and probably marine. for the first time, in the carboniferous period, snails emerge from the waters, and walk upon the ground and breathe air; for, like the modern land snails, these creatures no doubt had air-sacks instead of gills. they come suddenly upon us--two species at once, and these representing two distinct forms of the snail tribe, the elongated and the rounded. they were very numerous. in the beds where they occur, probably thousands of specimens, more or less perfect, could be collected. were they the first-born of land snails? it would be rash to affirm this, more especially since in all the coal-fields of the world no specimens have been found except at one locality in nova scotia;[n] and in all the succeeding beds we meet with no more till we have reached a comparatively modern time. yet it is very unlikely that these creatures were in the coal period limited to one country, and that, after that period, they dropped out of existence for long ages, and then reappeared. still it may have been so. [n] bradley has recently announced the discovery of other species in the coal-field of illinois. the two oldest land snails. [illustration: fig. .--_pupa vetusta_, dawson. (_a_) natural size, (_b_) enlarged, (_c_) apex, enlarged, (_d_) sculpture, magnified.] [illustration: fig. .--_conulus priscus_, carpenter. (_a_) specimen enlarged, (_b_) sculpture, magnified.] there are cases of geographical limitation quite as curious now. here again another peculiarity meets us. if these are really the oldest land snails, it is curious that they are so small,--so much inferior to many of their modern successors even in the same latitudes. the climate of the coal period must have suited them, and there was plenty of vegetable food, though perhaps not the richest or most tender. there is no excuse for them in their outward circumstances. why, then, unlike so many other creatures, do they enter on existence in this poor and sneaking way. we must here for their benefit modify in two ways the statement broadly made in a previous chapter, that new types come in under forms of great magnitude. first, we often have, in advance of the main inroad of a new horde of animals, a few insignificant stragglers as a sort of prelude to the rest--precursors intimating beforehand what is to follow. we shall find this to be the case with the little reptiles of the coal, and the little mammals of the trias, preceding the greater forms which subsequently set in. secondly, this seems to be more applicable in the case of land animals then in the case of those of the waters. to the waters was the fiat to bring forth living things issued. they have always kept to themselves the most gigantic forms of life; and it seems as if new forms of life entering on the land had to begin in a small way and took more time to culminate. the circumstances in which the first specimens of carboniferous snails and gally-worms were found are so peculiar and so characteristic of the coal formation, that i must pause here to notice them, and to make of them an introduction to the next group of creatures we have to consider. in the coal formation in all parts of the world it is not unusual, as stated already in a previous page, to find erect trees or stumps of trees, usually sigillariæ, standing where they grew; and where the beds are exposed in coast cliffs, or road cuttings, or mines, these fossil trees can be extracted from the matrix and examined. they usually consist of an outer cylinder of coal representing the outer bark, while the space within, once occupied by the inner bark and wood, is filled with sandstone, sometimes roughly arranged in layers, the lowest of which is usually mixed with coaly matter or mineral charcoal derived from the fallen remains of the decayed wood, a kind of deposit which affords to the fossil botanist one of the best modes of investigating the tissues of these trees. these fossil stumps are not uncommon in the roofs of the coal-seams. in some places they are known to the miners as "coal pipes," and are dreaded by them in consequence of the accidents which occur from their suddenly falling after the coal which supported them has been removed. an old friend and helper of mine in carboniferous explorations had a lively remembrance of the fact that one of these old trees, falling into the mine in which he was working, had crushed his leg and given him a limp for life; and if he had been a few inches nearer to it would have broken his back. the manner in which such trees become fossilized may be explained as follows:--imagine a forest of sigillariæ growing on a low flat. this becomes submerged by subsidence or inundation, the soil is buried under several feet of sand or mud, and the trees killed by this agency stand up as bare and lifeless trunks. the waters subside, and the trees rapidly decay, the larvæ of wood-boring insects perhaps aiding in the process, as they now do in the american woods. the dense coaly outer bark alone resists decomposition, and stands as a hollow cylinder until prostrated by the wind or by the waters of another inundation, while perhaps a second forest or jungle has sprung up on the new surface. when it falls, the part buried in the soil becomes an open hole, with a heap of shreds of wood and bark in the bottom. such a place becomes a fit retreat for gally-worms and land-snails; and reptiles pursuing such animals, or pursued by their own enemies, or heedlessly scrambling among the fallen trunks, may easily fall into such holes and remain as prisoners. i remember to have observed, when a boy, a row of post-holes dug across a pasture-field and left open for a few days, and that in almost every hole one or two toads were prisoners. this was the fate which must have often befallen the smaller reptiles of the coal forests in the natural post-holes left by the decay of the sigillariæ. yet it may be readily understood that the combination of circumstances which would effect this result must have been rare, and consequently this curious fact has been as yet observed only in the coal formation of nova scotia; and in it only in one locality, and in this in one only out of more then sixty beds in which erect trees have been found. but these hollow trees must be filled up in order to preserve their contents; and as inundation and subsequent decay have been the grave-diggers for the reptiles, so inundations filled up their graves with sand, to be subsequently hardened into sandstone, burying up at the same time the newer vegetation which had grown upon the former surface. the idea that something interesting might be found in these erect stumps, first occurred to sir c. lyell and the writer while exploring the beautiful coast cliffs of western nova scotia in ; and it was in examining the fragments scattered on the beach that we found the bones of the first carboniferous reptile discovered in america, and the shell of the oldest known land snail. these were not, however, the earliest known instances of carboniferous reptiles. in , sir william logan found footprints of a reptile at horton bluff, in nova scotia, in rocks of lower carboniferous age. in , von dechen found reptilian bones in the coal-field of saarbruck; and in the same year dr. king found reptilian footprints in the carboniferous of pennsylvania. like robinson crusoe on his desert island, we saw the footprints before we knew the animals that produced them; and the fact that there were marks on a slab of shale or sandstone that must have been made by an animal walking on feet, was as clear and startling a revelation of the advent of a new and higher form of life, as were the footprints of man friday. within the thirty years since the discovery of the first slab of footprints, the knowledge of coal formation reptiles has grown apace. i can scarcely at present sum up exactly the number of species, but may estimate it at thirty-five at least. i must, however, here crave pardon of some of my friends for the use of the word reptile. in my younger days frogs and toads and newts used to be reptiles; now we are told that they are more like fishes, and ought to be called batrachians or amphibians, whereas reptiles are a higher type, more akin to birds then to these lower and more grovelling creatures. the truth is, that the old class reptilia bridges over the space between the fishes and the birds, and it is in some degree a matter of taste whether we make a strong line at the two ends of it alone, or add another line in the middle. i object to the latter course, however, in the period of the world's history of which i am now writing, since i am sure that there were animals in those days which were batrachians in some points and true reptiles in others; while there are some of them in regard to which it is quite uncertain whether they are nearer to the one group or the other. although, therefore, naturalists, with the added light and penetration which they obtain by striding on to the mesozoic and modern periods, may despise my old-fashioned grovellers among the mire of the coal-swamps, i shall, for convenience, persist in calling them reptiles in a general way, and shall bring out whatever claims i can to justify this title for some of them at least. perhaps the most fish-like of the whole are the curious creatures from the coal measures of saarbruck, first found by yon dechen, and which constitute the genus _archegosaurus_. their large heads, short necks, supports for permanent gills, feeble limbs, and long tails for swimming, show that they were aquatic creatures presenting many points of resemblance to the ganoid fishes with which they must have associated; still they were higher then these in possessing lungs and true feet, though perhaps better adapted for swimming then even for creeping. from these creatures the other coal reptiles diverge, and ascend along two lines of progress, the one leading to gigantic crocodile-like animals provided with powerful jaws and teeth, and probably haunting the margins of the waters and preying on fishes; the other leading to small and delicate lizard-like species, with well-developed limbs, large ribs, and ornate horny scales and spines, living on land and feeding on insects and similar creatures. [illustration: fig. .--restorations of baphetes, dendrerpeton. hylonomus, and hylerpeton, with carboniferous plants in the distance.] in the first direction we have a considerable number of species found in the jarrow coal-field in ireland, and described by professor huxley. some of them were like snakes in their general form, others more like lizards. still higher stand such animals as _baphetes_ and _eosaurus_ from the nova scotia coal-field and _anthracosaurus_ from that of scotland. the style and habits of these creatures it is easy to understand, however much haggling the comparative anatomists may make over their bones. they were animals of various size, ranging from a foot to at least ten feet in length, the body generally lizard-like in form, with stout limbs and a flattened tail useful in swimming. their heads were flat, stout, and massive, with large teeth, strengthened by the insertion and convolution of plates of enamel. the fore limbs were probably larger then the hind limbs, the better to enable them to raise themselves out of the water. the belly was strengthened by bony plates and closely imbricated scales, to resist, perhaps, the attacks of fishes from beneath, and to enable them without injury to drag their heavy bodies over trunks of trees and brushwood, whether in the water or on the land. their general aspect and mode of life were therefore by no means unlike those of modern alligators; and in the vast swamps of the coal measures, full of ponds and sluggish streams swarming with fish, such creatures must have found a most suitable habitat, and probably existed in great numbers, basking on the muddy banks, surging through the waters, and filling the air with their bellowings. the most curious point about these creatures is, that while rigid anatomy regards them as allied in structure more to frogs and toads and newts then to true lizards, it is obvious to common sense that they were practically crocodiles; and even anatomy must admit that their great ribs and breastplates, and powerful teeth and limbs, indicate a respiration, circulation, and general vitality, quite as high as those of the proper reptiles. hence, it happens that very different views are stated as to their affinities; questions into which we need not now enter, satisfied with the knowledge of the general appearance and mode of life of these harbingers of the reptilian life of the succeeding geological periods. in the other direction, we find several animals of small size but better developed limbs, leading to a group of graceful little creatures, quite as perplexing with regard to affinities as those first mentioned, but tending towards the smaller lizards of the modern world. at the top of these i may place the genus _hylonomus_ from hollow fossil trees of nova scotia, of which two species are represented as restored in our illustration. in these restorations i have adhered as faithfully as possible to the proportions of parts as seen in my specimens. imagine a little animal six or seven inches long, with small short head, not so flat as those of most lizards, but with a raised fore-head, giving it an aspect of some intelligence. its general form is that of a lizard, but with the hind feet somewhat large, to aid it in leaping and standing erect, and long and flexible toes. its belly is covered with bony scales, its sides with bright and probably coloured scale armour of horny consistency, and its neck and back adorned with horny crests, tubercles, and pendants. it runs, leaps, and glides through the herbage of the coal forests, intent on the pursuit of snails and insects, its eye glancing and its bright scales shining in the sun. this is a picture of the best known species of hylonomus drawn from the life. yet the anatomist, when he examines the imperfectly-ossified joints of its backbone, and the double joint at the back of its skull, will tell you that it is after all little better then a mere newt, an ass in a lion's skin, a jackdaw with borrowed feathers, and that it has no right to have fine scales, or to be able to run on the land. it may be so; but i may plead in its behalf, that in the old coal times, when reptiles with properly-made skeletons had not been created, the next best animals may have been entitled to wear their clothes and to assume their functions as well. in short, functionally or officially, our ancient batrachians were reptiles; in point of rank, as measured by type of skeleton, they belonged to a lower grade. to this view of the case i think most naturalists will agree, and they will also admit that the progress of our views has been in this direction, since the first discovery of carboniferous air-breathing vertebrates. in evidence of this i may quote from professor huxley's description of his recently found species,[o] after noticing the prevalent views that the coal reptiles were of low organization, he says: "discoveries in the nova scotia coal-fields first shook this view, which ceased to be tenable when the great _anthracosaurus_ of the scotch coal-field was found to have well-ossified biconcave vertebrae." [o] _geological magazine_, vol. iii. the present writer may, however, be suspected of a tendency to extend forms of life backward in time, since it has fallen to his lot to be concerned in this process of stretching backward in several cases. he has named and described the oldest known animal. he has described the oldest true exogen, and the oldest known pine-tree. he was concerned in the discovery of the oldest known land snails, and found the oldest millipedes. he has just described the oldest bituminous bed composed of spore-cases, and he claims that his genus hylonomus includes the oldest animals which have a fair claim to be considered reptiles. still this discovery of old things comes rather of fortune and careful search then of a desire to innovate; and a distinction should be drawn between that kind of novelty which consists in the development of new truths, and that which consists in the invention of new fancies, or the revival of old ones. there is too much of this last at present; and it would be a more promising line of work for our younger naturalists, if they would patiently and honestly question nature, instead of trying to extort astounding revelations by throwing her on the rack of their own imaginations. we may pause here a moment to contemplate the greatness of the fact we have been studying the introduction into our world of the earliest known vertebrate animals which could open their nostrils and literally "breathe the breath of life." all previous animals that we know, except a few devonian insects, had respired in the water by means of gills or similar apparatus, now we not only have the little land snails, with their imperfect substitutes for lungs, but animals which must have been able to draw in the vital air into capacious chambered lungs, and with this power must have enjoyed a far higher and more active style of vitality; and must have possessed the faculty of uttering truly vocal sounds. what wondrous possibilities unknown to these creatures, perhaps only dimly perceived by such rational intelligences as may have watched the growth of our young world, were implied in these gifts. it is one of the remarkable points in the history of creation in genesis, that this step of the creative work is emphatically marked. of all the creatures we have noticed up to this point, it is stated that god said, "let the waters bring them forth"--but it is said that "god created" great reptiles (_tanninim_).[p] no doubt these "great tanninim" culminate in the succeeding mesozoic age, but their first introduction dates as far back as the carboniferous; and this introduction was emphatically a creation, as being the commencement of a new feature among living beings. what further differences may be implied in the formulæ, "let the waters produce" and "god created," we do not know; very probably he who wrote the words did not fully know. but if we could give a scientific expression to this difference, and specify the cases to which its terms apply, we might be able to solve one of the most vexed questions of biology. [p] not "whales," as in our version. let us observe, however, that even here, where, if anywhere, we have actual creation, especial pains are taken to bridge over the gap, and to prevent any appearance of discontinuity in the work. the ganoid fishes of the coal period very probably had, like their modern congeners, well-developed air-bladders, serving to some extent, though very imperfectly, as lungs. the humbler and more aquatic reptiles of the period retained the gills, and also some of the other features of the fishes; so that, like some modern creatures of their class, they stood, as to respiration, on two stools, and seemed unwilling altogether to commit themselves to the new mode of life in the uncongenial element of air. even the larger and more lizard-like of the coal reptiles may--though this we do not certainly know, and in some cases there are reasons for doubting it--have passed the earliest stage of their lives in the water as gilled tadpoles, in the manner of our modern frogs. thus at the very point where one of the greatest advances of animal life has its origin, we have no sudden stop, but an inclined plane; and yet, as i have elsewhere endeavoured to show by arguments which cannot be repeated here,[q] we have not a shadow of reason to conclude that, in the coal period, fishes were transmuted into reptiles. [q] "air-breathers of the coal period," p. . but the reader may be wearied with our long sojourn in the pestilential atmosphere of the coal swamps, and in the company of their low-browed and squalid inhabitants. let us turn for a little to the sea, and notice the animal life of the great coral reefs and shell beds preserved for us in the carboniferous limestone. before doing so, one point merits attention. the coal formation for the first time distinctly presents to us the now familiar differences in the inhabitants of the open sea and those of creeks, estuaries and lakes. such distinctions are unknown to us in the silurian. there all is sea. they begin to appear in the devonian, in the shallow fish-banks and the anodon-like bivalves found with fossil plants. in the coal period they become very manifest. the animals found in the shales with the coal are all, even the aquatic ones, distinct from those of the open seas of the period. some of them may have lived in salt or brackish water, but not in the open sea. they are creatures of still and shallow waters. it is true that in some coal-fields marine beds occur in the coal measures with their characteristic fossils, but these are quite distinct from the usual animal remains of the coal-fields, and mark occasional overflows of the sea, owing to subsidence of the land. it is important to notice this geographical difference, marking the greater specialisation and division of labour, if we may so speak, that was in the process of introduction. the sea of the carboniferous period presented in the main similar great groups of animals to those of the devonian, represented however by different species. we may notice merely some of the salient points of resemblance or difference. the old types of corals continue in great force; but it is their last time, for they rapidly decay in the succeeding permian and disappear. the crinoids are as numerous and beautiful as in any other period, and here for the first time we meet with the new and higher type of the sea-urchin, in large and beautiful species. one curious group, that of the _pentremites_, a sort of larval form, is known here alone. among the lamp-shells we may note, as peculiarly and abundantly carboniferous, those with one valve very convex and the other very concave and anchored in the mud by long spines instead of a peduncle attached to stones and rocks.[r] there are many beautiful shells allied to modern scallops, and not a few sea-snails of various sorts. the grand _orthoceratites_ of the silurian diminish in size preparatory to their disappearance in the permian, and the more modern type of _nautilus_ and its allies becomes prevalent. among the crustaceans we may notice the appearance of the _limulus_, or king-crab, of which the single little species described by woodward from the upper silurian may be regarded as merely a prophecy. it is curious that the carboniferous king-crabs are very small, apparently another case of a new form appearing in humble guise; but as the young of modern king-crabs haunt creeks and swampy flats, while the adults live in the sea, it may be that only the young of the carboniferous species are yet known to us, the specimens found being mostly in beds likely to be frequented by the young rather then by the full-grown individuals. [r] the productidæ. the old order of the trilobites, which has accompanied us from primordial times, here fails us, and a few depauperated species alone remain, the sole survivors of their ancient race--small, unornamented, and feeble representatives of a once numerous and influential tribe. how strange that a group of creatures so numerous and apparently so well adapted to conditions of existence which still continue in the sea, should thus die out, while the little bivalved crustaceans, which began life almost as far back and lived on the same sea-floors with the trilobites, should still abound in all our seas; and while the king-crabs, of precisely similar habits with the trilobites, should apparently begin to prosper. equally strange is the fate of the great swimming eurypterids which we saw in the devonian. they also continue, but in diminished force, in the carboniferous, and there lay down for ever their well-jointed cuirasses and formidable weapons, while a few little shrimp-like creatures, their contemporaries, form the small point of the wedge of our great tribes of squillas and crabs and lobsters. some years ago the late lamented palæontologist, salter, a man who scarcely leaves his equal in his department, in conjunction with mr. henry woodward, prepared a sort of genealogical chart of the crustacea on which these facts are exhibited. some new species have since been discovered, and a little additional light about affinities has been obtained; but taken as it stands, the history of the crustacea as there shown in one glance, has in it more teaching on the philosophy of creation then i have been able to find in many ponderous quartos of tenfold its pretensions. had salter been enabled, with the aid of other specialists like woodward, to complete similar charts of other classes of invertebrate animals, scientific palaeontology in england would have been further advanced then it is likely to be in the next ten years. to return to our trilobites: one of the most remarkable points in their history is their appearance in full force in the primordial. in these rocks we have some of the largest in size--some species of paradoxides being nearly two feet long, and some of the very smallest. we have some with the most numerous joints, others with the fewest; some with very large tails, others with very small; some with no ornamentation, others very ornate; some with large eyes, others with none that have been made out, though it is scarcely probable that they were wholly blind. they increased in numbers and variety through the silurian and devonian, and then suddenly drop off at the end of the lower carboniferous. throughout their whole term of existence they kept rigidly to that type of the mud-plough which the king-crab still retains, and which renders the anterior extremity so different from that of the ordinary crustacea. they constitute one of the few cases in which we seem to see before us the whole history of an animal type; and the more we look into that history, the more do we wonder at their inscrutable introduction, the unity and variety mingled in their progress, and their strange and apparently untimely end. i have already referred (page ) to the use which barrande makes of this as an argument against theories of evolution; but must refer to his work for the details. one word more i must say before leaving their graves. i have reason to believe that they were not only the diggers of the burrows, and of the ladder-tracks and pitted tracks[s] of the silurian and primordial, but that with the strokes of their rounded or spinous tails, the digging of their snouts, and the hoe-work of their hard upper lips, or hypostomes, they made nearly all those strange marks in the primordial mud which have been referred to fucoids, and even to higher plants. the trilobites worked over all the mud bottoms of the primordial, even in places where no remains of them occur, and the peculiarities of the markings which they left are to be explained only by a consideration of the structures of individual species. [s] _climactichnites_ and _protichnites_. i had almost lost sight of the fishes of the carboniferous period, but after saying so much of those of the devonian, it would be unfair to leave their successors altogether unnoticed. in the carboniferous we lose those broad-snouted plate-covered species that form so conspicuous a feature in the devonian; and whatever its meaning, it is surely no accident that these mud-burrowing fishes should decay along with those crustacean mud-burrowers, the trilobites. but swarms of fishes remain, confined, as in the devonian, wholly to the two orders of the gar-fishes (_ganoids_) and the sharks (_placoids_). in the former we have a multitude of small and beautiful species haunting the creeks and ponds of the coal swamps, and leaving vast quantities of their remains in the shaly and even coaly beds formed in such places. such were the pretty, graceful fishes of the genera _palæoniscus_ and _amblypterus_. pursuing and feeding on these were larger ganoids, armed with strong bony scales, and formidable conical or sharp-edged teeth. of these were _rhizodus_ and _acrolepis_. there were besides multitudes of sharks whose remains consist almost wholly of their teeth and spines, their cartilaginous skeletons having perished. one group was allied to the few species of modern sharks whose mouths are paved with flat teeth for crushing shells. these were the most abundant sharks of the carboniferous--slow and greedy monsters, haunting shell banks and coral reefs, and grinding remorselessly all the shell-fishes that came in their way. there were also sharks furnished with sharp and trenchant teeth, which must have been the foes of the smaller mailed fishes, pursuing them into creeks and muddy shallows; and if we may judge from the quantity of their remains in some of these places, sometimes perishing in their eager efforts. on the whole, the fishes of the carboniferous were, in regard to their general type, a continuation of those of the devonian, but the sharks and the scaly ganoids were relatively more numerous. they differed from our modern fishes in the absence of the ordinary horny-scaled type to which all our more common fishes belong, and in the prevalence of that style of tail which has been termed "heterocercal," in which the continuation of the backbone forms the upper lobe of the tail, a style which, if we may judge from modern examples, gives more power of upward and downward movement, and is especially suitable to fishes which search for food only at the bottom, or only above the surface of the waters. most reluctantly i must here leave one of the most remarkable periods of the world's history, and reserve to our next chapter the summation of the history of the older world of life in its concluding stage, the permian. chapter vii. the permian age and close of the palÆozoic. the immense swamps and low forest-clad plains which occupied the continental areas of the northern hemisphere, and which we now know extended also into the regions south of the equator, appear at the close of the carboniferous age to have again sunk beneath the waves, or to have relapsed into the condition of sand and gravel banks; for a great thickness of such deposits rests on the coal measures and constitutes the upper coal formation, the upper "barren measures" of the coal-miners. there is something grand in the idea of this subsidence of a world of animal and vegetable life beneath the waters. the process was very slow, so slow that at first vegetable growth and deposition of silt kept pace with it; and this is the reason of the immense series of deposits, in some places nearly , feet thick, which inclose or rest upon the coal beds; but at length it became more rapid, so that forests and their inhabitants perished, and the wild surf drifted sand and pebbles over their former abodes. so the carboniferous world, like that of noah, being overflowed with water, perished. but it was not a wicked world drowned for its sins, but merely an old and necessarily preliminary system, which had fully served its purpose; and, like the stubble of last year, must be turned under by the plough that it may make way for a new verdure. the plough passed over it, and the winter of the permian came, and then the spring of a new age. the permian and the succeeding triassic are somewhat chilly and desolate periods of the earth's history. the one is the twilight of the palæozoic day, the other is the dawn of the mesozoic. yet to the philosophical geologist no ages excel them in interest. they are times of transition, when old dynasties and races pass away and are replaced by new and vigorous successors, founding new empires and introducing new modes of life and action. three great leading points merit our attention in entering on the permian age. the first is the earth-movements of the period. the second is the resulting mineral characteristics of the deposits formed. the third is the aspect of the animal and vegetable life of this age in their relation more especially to those which preceded. [illustration: diagram of foldings of the crust in the permian period. (the vertical scale of heights and depressions exaggerated more then six times.) the lower figure shows a portion of folded strata in the appalachians--after rogers.] with respect to the first point above named, the earth's crust was subjected in the permian period to some of the grandest movements which have occurred in the whole course of geologic time, and we can fix the limits of these, in europe and america at least, with some distinctness. if we examine the permian rocks in england and germany, we shall find that everywhere they lie on the upturned edges of the preceding carboniferous beds. in other words, the latter have been thrown into a series of folds, and the tops of these folds have been more or less worn away before the permian beds were placed on them. but if we pass on to the eastward, in the great plain between the volga and the ural mountains, where, in the "ancient kingdom of perm," the greatest known area of these rocks is found, an area equal in extent to twice that of france, and which sir r. i. murchison, who first proposed the name, took as the typical district, we find, on the contrary, that the permian and carboniferous are conformable to one another. if now we cross the atlantic and inquire how the case stands in america, we shall find it precisely the same. here the great succession of earth-waves constituting the appalachian mountains rises abruptly at the eastern edge of the continent, and becomes flatter and flatter, until, in the broad plains west of the mississippi, the permian beds appear, as in russia, resting upon the carboniferous so quietly that it is not always easy to draw a line of separation between them. as dana has remarked, we find at the western side of europe and the eastern side of america, great disturbances inaugurating the permian period; and in the interior of both, in the plains between the volga and the ural in one, and between the mississippi and rocky mountains in the other, an entire absence of these disturbances. the main difference is, that in eastern america the whole carboniferous areas have apparently been so raised up that no permian was deposited on them, while in europe considerable patches of the disturbed areas became or remained submerged. another american geologist has largely illustrated the fact that the movements which threw up the appalachian folds were strongest to the eastward, and that the ridges of rock are steepest on their west sides, the force which caused them acting from the direction of the sea. it seems as if the atlantic area had wanted elbow-room, and had crushed up the edges of the continents next to it. in other words, in the lapse of the palæozoic ages the nucleus of the earth had shrunk away from its coating of rocky layers, which again collapsed into great wrinkles. such a process may seem difficult of comprehension. to understand it we must bear in mind some of its conditions. first, the amount of this wrinkling was extremely small relatively to the mass of the earth. in the diagram on page it is greatly exaggerated, yet is seen to be quite insignificant, however gigantic in comparison with microscopic weaklings like ourselves. secondly, it was probably extremely slow. beds of solid rock cannot be suddenly bent into great folds without breaking, and the abruptness of some of the folds may be seen from our figure, copied from rogers (page ), of some of the foldings of the appalachian mountains. thirdly, the older rocks below the carboniferous and the devonian must have been in a softened and plastic state, and so capable of filling up the vacancies left by the bending of the hard crust above. in evidence of this, we have in the lower permian immense volcanic ejections--lavas and other molten rocks spewed out to the surface from the softened and molten masses below. fourthly, the basin of the atlantic must have been sufficiently strong to resist the immense lateral pressure, so that the yielding was all concentrated on the weaker parts of the crust near the old fractures at the margins of the great continents. in these places also, as we have seen in previous papers, the greatest thickness of deposits had been formed; so that there was great downward pressure, and probably, also, greater softening of the lower part of the crust. fifthly, as suggested in a previous chapter, the folding of the earth's crust may have resulted from the continued shrinkage of its interior in consequence of cooling, leading after long intervals to collapse of the surface. astronomers have, however, suggested another cause. the earth bulges at the equator, and is flattened at the poles in consequence of, or in connection with, the swiftness of its rotation; but it has been shown that the rotation of the earth is being very gradually lessened by the attraction of the moon.[t] pierce has recently brought forward the idea[u] that this diminution of rotation, by causing the crust to subside in the equatorial regions and expand in the polar, might produce the movements observed; and which, according to lesley, have amounted in the whole course of geological time to about two per cent, of the diameter of our globe. we thus have two causes, either of which seems sufficient to produce the effect. [t] sir william thomson, who quotes adams and delaunay. [u] "nature," february, . viewed in this way, the great disturbances at the close of the palæozoic period constitute one of the most instructive examples in the whole history of the earth of that process of collapse to which the crust was subject after long intervals, and of which no equally great instance occurs except at the close of the laurentian and the close of the mesozoic. the mineral peculiarities of the permian are also accounted for by the above considerations. let us now notice some of these. in nearly all parts of the world the permian presents thick beds of red sandstone and conglomerate as marked ingredients. these, as we have already seen, are indications of rapid deposition accompanying changes of level. in the permian, as elsewhere, these beds are accompanied by volcanic rocks, indicating the subterranean causes of the disturbances. again, these rocks are chiefly abundant in those regions, like western europe, where the physical changes were at a maximum. another remarkable feature of the permian rocks is the occurrence of great beds of magnesian limestone, or dolomite. in england, the thick yellow magnesian limestone, the outcrop of which crosses in nearly a straight line through durham, yorkshire, and nottingham, marks the edge of a great permian sea extending far to the eastward. in the marls and sandstones of the permian period there is also much gypsum. now, chemistry shows us that magnesian limestones and gypsums are likely to be deposited where sea water, which always contains salts of magnesia, is evaporating in limited or circumscribed areas into which carbonate of lime and carbonate of soda are being carried by streams from the land or springs from below;[v] and it is also to be observed that solutions of sulphuric acid, and probably also of sulphate of magnesia, are characteristic products of igneous activity. hence we find in various geological periods magnesian limestones occurring as a deposit in limited shallow sea basins, and also in connection with volcanic breccias. now these were obviously the new permian conditions of what had once been the wide flat areas of the carboniferous period. still further, we find in europe, as characteristic of this period, beds impregnated with metallic salts, especially of copper. of this kind are very markedly the copper slates of thuringia. such beds are not, any more then magnesian limestones, limited to this age; but they are eminently characteristic of it. to produce them it is required that water should bring forth from the earth's crust large quantities of metallic salts, and that these should come into contact with vegetable matters in limited submerged areas, so that sulphates of the metals should be deoxidized into sulphides. a somewhat different chemical process, as already explained, was very active in the coal period, and was connected with the production of its iron ores; but, in the permian, profound and extensive fractures opened up the way to the deep seats of copper and other metals, to enrich the copper slate and its associated beds. it is also to be observed that the alkaline springs and waters which contain carbonate of soda, very frequently hold various metallic salts; so that where, owing to the action of such waters, magnesian limestone is being deposited, we may expect also to find various metallic ores. [v] hunt, "silliman's journal," and . let us sum up shortly this history. we have foldings of the earth's crust, causing volcanic action and producing limited and shallow sea-basins, and at the same time causing the evolution of alkaline and metalliferous springs. the union of these mechanical and chemical causes explains at once the conglomerates, the red sandstones, the trap rocks, the magnesian limestones, the gypsum, and the metalliferous beds of the permian. the same considerations explain the occurrence of similar deposits in various other ages of the earth's history; though, perhaps, in none of these were they so general over the northern hemisphere as in the permian. from the size of the stones in some of the permian conglomerates, and their scratched surfaces, it has been supposed that there were in this period, on the margins of the continents, mountains sufficiently high to have snow-clad summits, and to send down glaciers, bearing rocks and stones to the sea, on which may have floated, as now in the north atlantic, huge icebergs.[w] this would be quite in accordance with the great elevation of land which we know actually occurred; and the existence of snow-clad mountains along with volcanoes would be a union of fire and frost of which we still have examples in some parts of the earth's surface, and this in proximity to forms of vegetable life very similar to those which we know existed in the permian. [w] ramsay has ably illustrated this in the permian conglomerates of england. with the exception of a few small and worthless beds in russia, the permian is not known to contain any coal. the great swamps of the coal period had disappeared. in part they were raised up into rugged mountains. in part they were sunken into shallow sea areas. thus, while there was much dry land, there was little opportunity for coal production, or for the existence of those rank forests which had accumulated so much vegetable matter in the carboniferous age. in like manner the fauna of the permian waters is poor. according to murchison, the permian limestones of europe have afforded little more then one-third as many species of fossils as the older carboniferous. the fossils themselves also have a stunted and depauperated aspect, indicating conditions of existence unfavourable to them. this is curiously seen in contrasting davidson's beautiful illustrations of the british lamp-shells of the permian and carboniferous periods. another illustrative fact is the exceptionally small size of the fossils even in limestones of the carboniferous period when these are associated with gypsum, red sandstones, and magnesian minerals; as, for instance, those of some parts of nova scotia. in truth, the peculiar chemical conditions conducive to the production of magnesian limestones and gypsum are not favourable to animal life, though no doubt compatible with its existence. hence the rich fauna of the carboniferous seas died out in the permian, and was not renewed; and the atlantic areas of the period are unknown to us. they were, however, probably very deep and abrupt in slope, and not rich in life. this would be especially the case if they were desolated by cold ice-laden currents. during the permian period there was in each of our continental areas a somewhat extensive inland sea. that of western america was a northward extension of the gulf of mexico. that of eastern europe was a northward extension of the euxine and caspian. in both, the deposits formed were very similar--magnesian limestones, sandstones, conglomerates, marls, and gypsums. in both, these alternate in such a way as to show that there were frequent oscillations of level, producing alternately shallow and deep waters. in both, the animal remains are of similar species, in many instances even identical. but in the areas intervening between these sea basins and the atlantic the conditions were somewhat different. in europe the land was interrupted by considerable water areas, not lakes, but inland sea basins; sometimes probably connected with the open sea, sometimes isolated. in these were, deposited the magnesian limestone and its associated beds in england, and the zechstein and rotheliegende with their associates in germany. in america the case was different. in all that immense area which extends from the atlantic to the plains east of the mississippi, we know no permian rocks, unless a portion of those reckoned as upper carboniferous, or permo-carboniferous in northern nova scotia, and prince edward island, should be included in this group. if such existed, they may possibly be covered up in some places by more modern deposits, or may have been swept away by denudation in the intervening ages; but even in these cases we should expect to find some visible remains of them. their entire absence would seem to indicate that a vast, and in many parts rugged and elevated, continent represented north america in the permian period. yet if so, that great continent is an absolute blank to us. we know nothing of the animals or plants which may have lived on it, nor do we even know with certainty that it had active volcanoes, or snow-clad mountains sending down glaciers. our picture of the permian world has not been inviting, yet in many respects it was a world more like that in which we live then was any previous one. it certainly presented more of variety and grand physical features then any of the previous ages; and we might have expected that on its wide and varied continents some new and higher forms of life would have been introduced. but it seems rather to have been intended to blot out the old palæozoic life, as an arrangement which had been fully tried and served its end, preparatory to a new beginning in the succeeding age. still the permian has some life features of its own, and we must now turn to these. the first is the occurrence here, not only of the representatives of the great batrachians of the coal period, but of true reptiles, acknowledged to be such by all naturalists. the animals of the genus _protorosaurus_, found in rocks of this age both in england and germany, were highly-organised lizards, having socketed teeth like those of crocodiles, and well-developed limbs, with long tails, perhaps adapted for swimming. they have, however, biconcave vertebræ like the lizard-like animals of the coal already mentioned, which, indeed, in their general form and appearance, they must have very closely resembled. the protorosaurs were not of great size; but they must have been creatures of more stately gait then their carboniferous predecessors, and they serve to connect them with the new and greater reptiles of the next period. another interesting feature of the permian is its flora, which, in so far as known, is closely related to that of the coal period, though the species are regarded as different; some of the forms, however, being so similar as to be possibly identical. in a picture of the permian flora we should perhaps place in the foreground the tree-ferns, which seem to have been very abundant, and furnished with dense clusters of aërial roots to enable them to withstand the storms of this boisterous age. the tree-ferns, now so plentiful in the southern hemisphere, should be regarded as one of the permanent vegetable institutions of our world--those of the far-back lower devonian, and of all intervening ages up to the present day, having been very much alike. the great reed-like calamites have had a different fate. in their grander forms they make their last appearance in the permian, where they culminate in great ribbed stems, sometimes nearly a foot in diameter, and probably of immense height. the brakes of these huge mares'-tails which overspread the lower levels of the permian in europe, would have been to us what the hayfields of brobdingnag were to gulliver. the lepidodendra also swarmed, though in diminished force; but the great sigillariæ of the coal are absent, or only doubtfully present. another feature of the permian woods was the presence of many pine-trees different in aspect from those of the coal period. some of these are remarkable for their slender and delicate branches and foliage.[x] others have more dense and scaly leaves, and thick short cones.[y] both of these styles of pines are regarded as distinct, on the one hand, from those of the coal formation, and on the other from those of the succeeding trias. i have shown, however, many years ago, that in the upper coal formation of america there are branches of pine-trees very similar to walchia, and, on the other hand, the permian pines are not very remote in form and structure from some of their modern relations. the pines of the first of the above-mentioned types (walchia) may indeed be regarded as allies of the modern araucarian pines of the southern hemisphere, and of the old conifers of the carboniferous. those of the second type (ulmannia) may be referred to the same group with the magnificent sequoias or redwoods of california. [x] walchia. [y] ulmannia. it is a curious indication of the doubts which sometimes rest on fossil botany, that some of the branches of these permian pines, when imperfectly preserved, have been described as sea-weeds, while others have been regarded as club-mosses. it is true, however, that the resemblance of some of them to the latter class of plants is very great; and were there no older pines, we might be pardoned for imagining in the permian a transition from club-mosses to pines. unfortunately, however, we have pines nearly as far back in geological time as we have club-mosses; and, in so far as we know, no more like the latter then are the pines of the permian, so that this connection fails us. in all probability the permian forests are much less perfectly known to us then those of the coal period, so that we can scarcely make comparisons. it appears certain, however, that the permian plants are much more closely related to the coal plants then to those of the next succeeding epoch, and that they are not so much a transition from the one to the other as the finishing of the older period to make way for the newer. but we must reserve some space for a few remarks on the progress and termination of the palæozoic as a whole, and on the place which it occupies in the world's history. these remarks we may group around the central question, what is the meaning or value of an age or period in the history of the earth, as these terms are understood by geologists? in most geological books terms referring to time are employed very loosely. period, epoch, age, system, series, formation, and similar terms, are used or abused in a manner which only the indefiniteness of our conceptions can excuse. a great american geologist[z] has made an attempt to remedy this by attaching definite values to such words as those above mentioned. in his system the greater divisions of the history were "times:" thus the eozoic was a time and the palæozoic was a time. the larger divisions of the times are "ages:" thus the lower and upper silurian, the devonian, and the carboniferous are ages, which are equivalent in the main to what english geologists call systems of formations. ages, again, may be divided into "periods:" thus, in the upper silurian, the ludlow of england, or lower helderberg of america, would constitute a period. these periods may again be divided into "epochs," which are equivalent to what english geologists call formations, a term referring not directly to the time elapsed, but to the work done in it. now this mode of regarding geological time introduces many thoughts as to the nature of our chronology and matters relating to it. a "time" in geology is an extremely long time, and the palæozoic was perhaps the longest of the whole. by the close of the palæozoic nine-tenths of all the rocks we know in the earth's crust were formed. at least this is the case if we reckon mere thickness. for aught that we know, the eozoic time may have accumulated as much rock as the palæozoic; but leaving this out of the question, the rocks of the palæozoic are vastly thicker then those of the mesozoic and cainozoic united. thus the earth's history seems to have dragged slowly in its earlier stages, or to have become accelerated in its latter times. to place it in another point of view, life changes were greater relatively to merely physical changes in the later then in the earlier times. [z] dana. the same law seems to have obtained within the palæozoic time itself. its older periods, as the cambrian and lower silurian, present immense thicknesses of rock with little changes in life. its later periods, the carboniferous and permian, have greater life-revolution relatively to less thickness of deposits. this again was evidently related to the growing complexity and variety of geographical conditions, which went on increasing all the way up to the permian, when they attained their maximum for the palæozoic time. again, each age was signalized, over the two great continental plateaus, by a like series of elevations and depressions. we may regard the siluro-cambrian, the silurian, the devonian, the carboniferous, and permian, as each of them a distinct age. each of these began with physical disturbances and coarse shallow-water deposits. in each this was succeeded by subsidence and by a sea area tenanted by corals and shell-fishes. in each case this was followed by a re-elevation, leading to a second but slow and partial subsidence, to be followed by the great re-elevation preparatory to the next period. thus we have throughout the palæozoic a series of cycles of physical change which we may liken to gigantic pulsations of the thick hide of mother earth. the final catastrophe of the permian collapse was quite different in kind from these pulsations as well as much greater in degree. the cambrian or primordial does not apparently present a perfect cycle of this kind, perhaps because in that early period the continental plateaus were not yet definitely formed, and thus its beds are rather portions of the general oceanic deposit. in this respect it is analogous in geological relations to the chalk formation of a later age, though very different in material. the cambrian may, however, yet vindicate its claim to be regarded as a definite cycle: and the recent discoveries of hicks in north wales, have proved the existence of a rich marine fauna far down in the lower part of this system. it is also to be observed that the peculiar character of the cambrian, as an oceanic bottom rather then a continental plateau, has formed an important element in the difficulties in establishing it as a distinct group; just as a similar difficulty in the case of the chalk has led to a recent controversy about the continuance of the conditions of that period into modern times. but in each of the great successive heaves or pulsations of the palæozoic earth, there was a growing balance in favour of the land as compared with the water. in each successive movement more and more elevated land was thrown up, until the permian flexures finally fixed the forms of our continents. this may be made evident to the eye in a series of curves, as in the following diagram, in which i have endeavoured to show the recurrence of similar conditions in each of the great periods of the palæozoic, and thus their equivalency to each other as cycles of the earth's history. there is thus in these great continental changes a law of recurrence and a law of progress; but as to the efficient causes of the phenomena we have as yet little information. it seems that original fractures and shrinkages of the crust were concerned in forming the continental areas at first. once formed, unequal burdening of the earth's still plastic mass by deposits of sediment in the waters, and unequal expansion by the heating and crystallization of immense thicknesses of the sediment, may have done the rest; but the results are surprisingly regular to be produced by such causes. we shall also find that similar cycles can be observed in the geological ages which succeeded the palæozoic. geologists have hitherto for the most part been content to assign these movements to causes purely terrestrial; but it is difficult to avoid the suspicion that the succession of geological cycles must have depended on some recurring astronomical force tending to cause the weaker parts of the earth's crust alternately to rise and subside at regular intervals of time. herschel, adhémar, and more recently croll, have directed attention to astronomical cycles supposed to have important influences on the temperature of the earth. whether these or other changes may have acted on the equilibrium of its crust is a question well worthy of attention, as its solution might give us an astronomical measure of geological time. this question, however, the geologist must refer to the astronomer. [illustration: curves showing the successive elevations and depressions of the american continent, in several cycles of the palÆozoic time.] there are two notes of caution which must here be given to the reader. first, it is not intended to apply the doctrine of continental oscillations to the great oceanic areas. whether they became shallower or deeper, their conditions would be different from those which occurred in the great shallow plateaus, and these conditions are little known to us. further, throughout the palæozoic period, the oscillations do not seem to have been sufficient to reverse the positions of the oceans and continents. secondly, it is not meant to affirm that the great permian plications were so widespread in their effects as to produce a universal destruction of life. on the contrary, after they had occurred, remnants of the carboniferous fauna still flourished even on the surfaces of the continents, and possibly the inhabitants of the deep ocean were little affected by these great movements. true it is that the life of the palæozoic terminates with the permian, but not by a great and cataclysmic overthrow. we know something at least of the general laws of continental oscillations during the palæozoic. do we know anything of law in the case of life? the question raises so many and diverse considerations that it seems vain to treat it in the end of a chapter; still we must try to outline it with at least a few touches. first, then, the life of the palæozoic was remarkable, as compared with that of the present world, in presenting a great prevalence of animals and plants of synthetic types, as they are called by agassiz that is, of creatures comprehending in one the properties of several groups which were to exist as distinct in the future. such types are also sometimes called embryonic, because the young of animals and plants often show these comprehensive features. such types were the old corals, presenting points of alliance with two distinct groups now widely separated; the old trilobites, half king-crabs and half isopods; the amphibians of the coal, part fish, part newt, and part crocodile; the sigillariæ, part club-mosses and part pines; the orthoceratites, half nautili and half cuttle-fishes. i proposed, in the illustration in a former article, to give a restoration of one of the curious creatures last mentioned, the orthoceratites; but on attempting this, with the idea that, as usually supposed, they were straight nautili, it appeared that the narrow aperture, the small outer chamber, the thin outer wall, often apparently only membranous, and the large siphuncle, would scarcely admit of this; and i finished by representing it as something like a modern squid; perhaps wrongly, but it was evidently somewhere between them and the nautili. secondly, these synthetic types often belonged to the upper part of a lower group, or to the lower part of an upper group. hence in one point of view they may be regarded as of high grade, in another as of low grade, and they are often large in size or in vegetative development.[aa] from this law have arisen many controversies about the grade and classification of the palæozoic animals and plants. [aa] it seems, indeed, as if the new synthetic forms intermediate between great groups were often large in size, while the new special types came in as small species. there are some remarkable cases of this in the plant world; though here we have such examples as the pines and tree-ferns continuing almost unchanged from an early palæozoic period until now. thirdly, extinctions of species occur in every great oscillation of the continental areas, but some species reappear after such oscillations, and the same genus often recurs under new specific forms. families and orders, such as those of the trilobites and orthoceratites, appear to have a grand and gradual culmination and decadence extending over several successive periods, or even over the whole stretch of the palæozoic time. toward the close of the palæozoic, while all the species disappear, some whole families and orders are altogether dropped, and, being chiefly synthetic groups, are replaced by more specialised types, some of which, however, make small beginnings alongside of the more general types which are passing away. our diagram (page ) illustrates these points. [illustration: diagram showing the advance, culmination, and decadence of some of the leading types of palÆozoic life.] fourthly, the progress in animal life in the palæozoic related chiefly to the lower or invertebrate tribes, and to the two lower classes of the vertebrates. the oldest animal known to us is not only a creature of the simplest structure, but also a representative of that great and on the whole low type of animal life, in which the parts are arranged around a central axis, and not on that plan of bilateral symmetry which constitutes one great leading distinction of the higher animals. with the cambrian, bilateral animals abound and belong to two very distinct lines of progress--the one, the mollusks, showing the nutritive organs more fully developed--the other, the articulates, having the organs of sense and of locomotion more fully organized. these three great types shared the world among them throughout the earlier palæozoic time, and only in its later ages began to be dominated by the higher types of fishes and reptiles. in so far as we know, it remained for the mesozoic to introduce the birds and mammals. in plant life the changes were less marked, though here also there is progress--land plants appear to begin, not with the lowest forms, but with the highest types of the lower of the two great series into which the vegetable kingdom is divided. from this they rapidly rise to a full development of the lowest type of the flowering plants, the pines and their allies, and there the progress ceases; for the known representatives of the higher plants are extremely few and apparently of little importance. fifthly, in general the history tells of a continued series of alternate victories and defeats of the species that had their birth on the land and in the shallow waters, and those which were born in the ocean depths, the former spread themselves widely after every upheaval, and then by every subsidence were driven back to their mountain fastnesses. the latter perished from the continental plateaus at every upheaval, but climbed again in new hordes and reoccupied the ground after every subsidence. but just as in human history every victory or defeat urges on the progress of events, and develops the great plan of god's providence in the elevation of man; so here every succeeding change brings in new and higher actors on the stage, and the scheme of creation moves on in a grand and steady progress towards the more varied and elevated life of the modern world. but, after all, how little do we know of these laws, which are only beginning to dawn on the minds of naturalists; and which the imperfections of our classification and nomenclature, and the defects in our knowledge of fossil species, render very dim and uncertain. all that appears settled is the existence of a definite plan, working over long ages, and connected with the most remarkable correlation of physical and organic change: going on with regular march throughout the palæozoic, and then brought to a close to make room for another great succession. this following mesozoic time must next engage our attention. we may close for the present with presenting to the eye in tabular form the periods over which we have passed. the table on page , and the diagram (page ), mutually illustrate each other; and it will be seen that each age constitutes cycle, similar in its leading features to the other cycles, while each is distinguished by some important fact in relation to the introduction of living beings. in this table i have, with mr. hull,[ab] for simplicity, arranged the formations of each age under three periods--an older, middle, and newer. of these, however, the last or newest is in each case so important and varied as to merit division into two, in the manner which i have suggested in previous publications for the palæozoic rocks of north america.[ac] under each period i have endeavoured to give some characteristic example from europe and america, except where, as in the case of the coal formation, the same names are used on both continents. such a table as this, it must be observed, is only tentative, and may admit of important modifications. the laurentian more especially may admit of division into several ages; and a separate age may be found to intervene between it and the cambrian. the reader will please observe that this table refers to the changes on the continental plateaus; and that on both of these each age was introduced with shallow water and usually coarse deposits, succeeded by deeper water and finer beds, usually limestones, and these by a mixed formation returning to the shallow water and coarse deposits of the older period of the age. this last kind of deposition culminates in the great swamps of the coal formation. [ab] "quarterly journal of science," july, . [ac] "acadian geology," p. . condensed tabular view of the ages and periods of the palÆozoic and eozoic. key to symbols ### tabulate and rugose corals, abundant. *** age of algæ. === age of acrogens and gymnosperms. +++ and god said, "let the waters bring forth abundantly the swarming living creatures." --- and god created great reptiles. times. ages. periods. animals and plants. palÆozoic { {newer. red sandstones, # { rauchwacke, etc. # beginning = - {permian {middle. zechstein, or # of age = - { magnesian limestone. # of reptiles. = - { {older. conglomerates, etc., # = - { rotheliegendes. # = - { # = - { {n. coal formation. # = - {carboniferous {m. carboniferous limestone. # age of = - { {o. lower coal measures and # batrachians. = { conglomerates. # = { # = { {n. upper old red, chemung. # = {devonian {m. eifel and corniferous # = { { limestones. # age of fishes. = { or erian {o. lower old red, oriskany # = { { sandstone. # = + { # + { {n. ludlow, lower helderberg. # + {upper silurian {m. wenlock and niagara # + { { limestones. # age of + { {o. mayhill, etc., oneida # mollusks. + { { conglomerates. # + { # + { {n. caradoc, hudson r. # + {lower silurian {m. bala and trenton # + { or { limestones. # * + {siluro-cambrian {o. llandielo, etc., chazy. # * + { # * + { {n. lingula flags, etc., * + { { potsdam sandstone. * + { { {acadian, etc.? age of * + {cambrian {m. (uncertain){ crustaceans. * + { { {menevian? * + { {o. longmynd, huronian? + + eozoic + + { {n. anorthosite gneiss, etc. + {laurentian {m. eozoon limestones, etc. age of + { {o. lower gneiss. protozoa. + chapter viii. the mesozoic ages. physically, the transition from the permian to the trias is easy. in the domain of life a great gulf lies between; and the geologist whose mind is filled with the forms of the palæozoic period, on rising into the next succeeding beds, feels himself a sort of rip van winkle, who has slept a hundred years and awakes in a new world. the geography of our continents seems indeed to have changed little from the time of the permian to that next succeeding group which all geologists recognise as the beginning of the mesozoic or middle age of the world's history, the triassic period. where best developed, as in germany, it gives us the usual threefold series, conglomerates and sandstones below, a shelly limestone in the middle, and sandstones and marls above. curiously enough, the germans, recognising this tripartite character here more distinctly then in their other formations, named this the _trias_ or triple group, a name which it still retains, though as we have seen it is by no means the earliest of the triple groups of strata. in england, where the middle limestone is absent, it is a "new red sandstone," and the same name may be appropriately extended to eastern america, where bright red sandstones are a characteristic feature. in the trias, as in the permian, the continents of the northern hemisphere presented large land areas, and there were lagoons and landlocked seas in which gypsum, magnesian limestones, and rock salt were thrown down, a very eminent example of which is afforded by the great salt deposits of cheshire. there were also tremendous outbursts of igneous activity along the margins of the continents, more especially in eastern america. but with all this there was a rich land flora and a wonderful exuberance of new animal life on the land; and in places there were even swamps in which pure and valuable beds of coal, comparable with those of the old coal formation, were deposited. the triple division of the trias as a cycle of the earth's history, and its local imperfection, are well seen in the european development of the group, thus:-- german series. french series. english series. keuper, sandstone and } marnes irisées {saliferous and gypseous shale } { shales and sandstones. muschelkalk, limestone} calcaire coquillier {wanting. and dolomite } bunter, sandstone and } grès bigarré {sandstone and conglomerate } { conglomerate. the trias is succeeded by a great and complex system of formations, usually known as the jurassic, from its admirable development and exposure in the range of the jura; but which the english geologists often name the "oolitic," from the occurrence in it of beds of oolite or roe-stone. this rock, of which the beautiful cream-coloured limestone of bath is an illustration, consists of an infinity of little spheres, like seeds or the roe of a fish. under the microscope these are seen to present concentric layers, each with a radiating fibrous: structure, and often to have a minute grain of sand or fragment of shell in the centre. they are, in short, miniature concretions, produced by the aggregation of the calcareous matter around centres, by a process of molecular attraction to which fine sediments, and especially those containing much lime, are very prone. this style of limestone is very abundant in the jurassic system, but it is not confined to it. i have seen very perfect oolites in the silurian and the carboniferous. the jurassic series, as developed in england, may be divided into three triplets or cycles of beds, in the following way: {purbeck beds. upper jurassic {portland limestone. {portland sand. {kimmeridge clay, etc. middle jurassic {coral rag, limestone. {lower calcareous grit, oxford clay, etc. {cornbrash and forest marble. lower jurassic[ad] {great and inferior oolite, limestone. {lias clays and limestones. [ad] this last group is very complex, and might perhaps admit of sub division, locally at least, into subordinate cycles. these rocks occupy a large space in england, as the names above given will serve to show; and they are also largely distributed over the continent of europe and asia which had evidently three great and long-continued dips under water, indicated by the three great limestones. in america the case was different. the jurassic has not been distinctly recognised in any part of the eastern coast of that continent, which then perhaps extended farther into the atlantic then it does at present; so that no marine beds were formed on its eastern border. but in the west, along the base of the rocky mountains and also in the arctic area, there were jurassic seas of large extent, swarming with characteristic animals. at the close of the jurassic period our continents seem to have been even more extensive then at present. in england and the neighbouring parts of the continent of europe, according to lyell, the fresh-water and estuarine beds known as the wealden have been traced miles from west to east, and miles from north-west to south-east, and their thickness in one part of this area is estimated at no less then , feet. such a deposit is comparable in extent with the deltas of such great rivers as the niger or even the mississippi, and implies the existence of a continent much more extensive and more uniform in drainage then europe as it at present exists. lyell even speculates on the possible existence of an atlantic continent west of europe. america also at this time had, as already stated, attained to even more then its present extension eastwards. thus this later jurassic period was the culmination of the mesozoic, the period of its most perfect continental development, corresponding in this to the carboniferous in the palæozoic. the next or closing period of this great mesozoic time brought a wondrous change. in the cretaceous period, so called from the vast deposits of chalk by which it is characterized, the continents sunk as they had never sunk before, so that vast spaces of the great continental plateaus were brought down, for the first time since the laurentian, to the condition of abyssal depths, tenanted by such creatures as live in the deepest recesses of our modern oceans. this great depression affected europe more severely then america; the depression of the latter being not only less, but somewhat later in date. in europe, at the period of greatest submergence, the hills of scandinavia and of britain, and the urals, perhaps alone stood out of the sea. the alps and their related mountains, and even the himalayas, were not yet born, for they have on their high summits deep-sea beds of the cretaceous and even of later date. in america, the appalachians and the old laurentian ranges remained above water; but the rocky mountains and the andes were in great part submerged, and a great cretaceous sea extended from the appalachians westward to the pacific, and southward to the gulf of mexico, opening probably to the north into the arctic ocean. this great depression must have been of very long continuance, since in western europe it sufficed for the production of nearly , feet in thickness of chalk, a rock which, being composed almost entirely of microscopic shells, is, as we shall see in the sequel, necessarily of extremely slow growth. if we regard the cretaceous group as one of our great ages or cycles, it seems to be incomplete. the sandstones and clays known as the greensand and gault constitute its lower or shallow-water member. the chalk is its middle or deep-sea member, but the upper shallow-water member is missing, or only very locally and imperfectly developed. and the oldest of the succeeding tertiary deposits, which indicate much less continuous marine conditions, rest on the chalk, as if the great and deep sea of the cretaceous age had been suddenly upheaved into land. this abrupt termination of the last cycle of the mesozoic is obviously the reason of the otherwise inexplicable fact that the prevalent life of the period ceases at the top of the chalk, and is exchanged immediately and without any transition for the very different fauna of the tertiary. this further accords with the fact that the cretaceous subsidence ended in another great crumpling of the crust, like that which distinguished the permian. by this the mesozoic time was terminated and the cainozoic inaugurated; while the rocky mountains, the andes, the alps, and the himalayas, rose to importance as great mountain ranges, and the continents were again braced up to retain a condition of comparative equilibrium during that later period of the earth's chronology to which we ourselves belong. [illustration: life on land in the mesozoic period. in the foreground are a pine, cycads, and a pandanus; also small mammals, an herbivorous dinosaur, and a labyrinthodont. in the distance are other dinosaurs and crocodiles. in the air are birds (_archæopterux_) and pterodactyls. was the length of the mesozoic time equal to that of the palæozoic? measured by recurring cycles it was. in the latter period we find five great cycles, from the lower silurian to the permian inclusive. so in the mesozoic we have five also, from the trias to the cretaceous inclusive. we have a right to reckon these cycles as ages or great years of the earth; and so reckoning them, the mesozoic time may have been as long as the palæozoic. but if we take another criterion the result will be different. the thickness of the deposits in the palæozoic as compared with the mesozoic, where these are severally best developed, may be estimated as at least four or five to one; so that if we suppose the beds to have been formed with equal rapidity in the two great periods, then the older of the two was between four and five times as long as the latter, which would indeed be only a little greater then one of the separate ages of the palæozoic. either, therefore, the deposits took place with greater rapidity in the palæozoic, or that period was by much the longer of the two. this it will be observed, is only another aspect of the great laws of geological sequence referred to in our last paper. let us look into this question a little more minutely. if the several pulsations of our continents depended upon any regularly recurring astronomical or terrestrial change, then they must represent, at least approximately, equal portions of time, and this, if proved, would settle the question in favour of an equal duration of these two great eras of the earth's history. but as we cannot yet prove this, we may consider what light we can derive from the nature of the rocks produced. these may be roughly classified as of two kinds: first, the beds of sediment, sand, clay, etc., accumulated by the slow chemical decay of rocks and the mechanical agency of water. secondly, the beds formed by accumulation of the harder and less perishable parts of living beings, of which the limestones are the chief. with reference to the first of these kinds of deposit, the action of the atmosphere and rains on rocks in the earlier times might have been somewhat more powerful if there was more carbonic acid in the atmosphere, that substance being the most efficient agent in the chemical decay of rocks. it might have been somewhat more powerful if there was a greater rainfall. it must, on the other hand, have been lessened by the apparently more equable temperature which then prevailed. these differences might perhaps nearly balance one another. then the rocks of the older time were quite as intractable as those of the newer, and they were probably neither so high nor so extensive. further, the dips and emergences of the great continental plateaus were equally numerous in the two great periods, though they were probably, with the exception of the latest one of each, more complete in the older period. in so far, then, as deposition of sediment is concerned, these considerations would scarcely lead us to infer that it was more rapid in the palæozoic. but the palæozoic sediments may be estimated in the aggregate at about , feet in thickness, while those of the mesozoic scarcely reach , . we might, therefore, infer that the palæozoic period was perhaps five or six times as long as the mesozoic. if we take the second class of rocks, the limestones, and suppose these to have been accumulated by the slow growth of corals, shells, etc., in the sea, we might, at first sight, suppose that palæozoic animals would not grow or accumulate limestone faster then their mesozoic successors. we must, however, consider here the probability that the older oceans contained more lime in solution then those which now exist, and that the equable temperature and extensive submerged plateaus gave very favourable conditions for the lower animals of the sea, so that it would perhaps be fair to allow a somewhat more rapid rate of growth of limestone for the palæozoic. now the actual proportions of limestone may be roughly stated at , feet in the palæozoic, and , feet in the mesozoic, which would give a proportion of about four and a quarter to one; and as a foot of limestone may be supposed on the average to require five times as long for its formation as a foot of sediment, this would give an even greater absolute excess in favour of the palæozoic on the evidence of the limestones an excess probably far too great to be accounted for by any more favourable conditions for the secretion of carbonate of lime by marine animals. the data for such calculations are very uncertain, and three elements of additional uncertainty closely related to each other must also be noticed. the first is the unknown length of the intervals in which no deposition whatever may have been taking place over the areas open to our investigation. the second is the varying amounts in which material once deposited may have been swept away by water. the third is the amount of difference that may have resulted from the progressive change of the geographical features of our continents. these uncertainties would all tend to diminish our estimate of the relative length of the mesozoic. lastly, the changes that have taken place in living beings, though a good measure of the lapse of time, cannot be taken as a criterion here, since there is much reason to believe that more rapid changes of physical conditions act as an inducing cause of rapid changes of life. on the whole, then, taking such facts as we have, and making large deductions for the several causes tending to exaggerate our conception of palæozoic time, we can scarcely doubt that the palæozoic may have been three times as long as the mesozoic. if so, the continental pulsations, and the changes in animal and vegetable life, must have gone on with accelerated rapidity in the later period,--a conclusion to which we shall again have occasion to refer when we arrive at the consideration of the tertiary or neozoic time, and the age of man, and the probable duration of the order of things under which we live. i have given this preliminary sketch of the whole mesozoic time, because we cannot here, as in the palæozoic, take up each age separately; and now we must try to picture to ourselves the life and action of these ages. in doing so we may look at, first, the plant life of this period; second, animal life on the land; and third, animal life in the waters and in the ocean depths. the mesozoic shores were clothed with an abundant flora, which changed considerably in its form during the lapse of this long time; but yet it has a character of its own distinct from that of the previous palæozoic and the succeeding tertiary. perhaps no feature of this period is more characteristic then the great abundance of those singular plants, the cycads, which in the modern flora are placed near to the pines, but in their appearance and habit more resemble palms, and which in the modern world are chiefly found in the tropical and warm temperate zones of asia and america. no plants certainly of this order occur in the carboniferous, where their nearest allies are perhaps some of the sigillariæ; and in the modern time the cycads are not so abundant, nor do they occur at all in climates where their predecessors appear to have abounded. in the quarries of the island of portland, we have a remarkable evidence of this in beds with numerous stems of cycads still _in situ_ in the soil in which they grew, and associated with stumps of pines which seem to have flourished along with them. in further illustration of this point, i may refer to the fact that carruthers, in a recent paper, catalogues twenty-five british species belonging to eight genera--a fact which markedly characterizes the british flora of the mesozoic period. these plants will therefore occupy a prominent place in our restoration of the mesozoic landscape, and we should give especial prominence to the beautiful species _williamsonia gigas_, discovered by the eminent botanist whose name it bears, and restored in his paper on the plant in the "linnæan transactions." these plants, with pines and gigantic equisetums, prevailed greatly in the earlier mesozoic flora, but as the time wore on, various kinds of endogens, resembling the palms and the screw-pines of the tropical islands, were introduced, and toward its close some representatives of the exogens very like our ordinary trees. among these we find for the first time in our upward progress in the history of the earth, species of our familiar oaks, figs, and walnut, along with some trees now confined to australia and the cape of good hope, as the banksias and "silver-trees," and their allies. in america a large number of the genera of the modern trees are present, and even some of those now peculiar to america, as the tulip-trees and sweet-gums. these forests of the later mesozoic must therefore have been as gay with flowers and as beautiful in foliage as those of the modern world, and there is evidence that they swarmed with insect life. further, the mesozoic plants produced in some places beds of coal comparable in value and thickness to those of the old coal formation. of this kind are the coal beds of brora in sutherlandshire, those of richmond in virginia, and deep river in n. carolina, those of vancouver's island, and a large part of those of china. to the same age have been referred some at least of the coal beds of australia and india. so important are these beds in china, that had geology originated in that country, the mesozoic might have been our age of coal. if the forests of the mesozoic present a great advance over those of the palæozoic, so do the animals of the land, which now embrace all the great types of vertebrate life. some of these creatures have left strange evidence of their existence in their footprints on the sand and clay, now cemented into beds of hard rock excavated by the quarryman. if we had landed on some wide muddy mesozoic shore, we might have found it marked in all directions with animal footprints. some of these are shaped much like a human hand. the creature that made this mark was a gigantic successor of the crocodilian newts or labyrinthodonts of the carboniferous, and this type seems to have attained its maximum in this period, where one species, _labyrinthodon giganteus_, had great teeth three or four inches in length, and presenting in their cross section the most complicated foldings of enamel imaginable. but we may see on the shores still more remarkable footprints. they indicate biped and three-toed animals of gigantic size, with a stride perhaps six feet in length. were they enormous birds? if so, the birds of this age must have been giants which would dwarf even our ostriches. but as we walk along the shore we see many other impressions, some of them much smaller and different in form. some, again, very similar in other respects, have four toes; and, more wonderful still, in tracing up some of the tracks, we find that here and there the creature has put down on the ground a sort of four-fingered hand, while some of these animals seem to have trailed long tails behind them. what were these portentous creatures--bird, beast, or reptile? the answer has been given to us by their bones, as studied by yon meyer and owen, and more recently by huxley and cope. we thus have brought before us the _dinosaurs_--the terrible saurians--of the mesozoic age, the noblest of the tanninim of old. these creatures constitute numerous genera and species, some of gigantic size, others comparatively small;--some harmless browsers on plants, others terrible renders of living flesh; but all remarkable for presenting a higher type of reptile organization then any now existing, and approaching in some respects to the birds and in others to the mammalia. let us take one example of each of the principal groups. and first marches before us the _iguanodon_ or his relation _hadrosaurus_--a gigantic biped, twenty feet or more in height, with enormous legs shaped like those of an ostrich, but of elephantine thickness. it strides along, not by leaps like a kangaroo, but with slow and stately tread, occasionally resting, and supporting itself on the tripod formed by its hind limbs and a huge tail, like the inverted trunk of a tree. the upper part of its body becomes small and slender, and its head, of diminutive size and mild aspect, is furnished with teeth for munching the leaves and fruits of trees, which it can easily reach with its small fore-limbs, or hands, as it walks through the woods. the outward appearance of these creatures we do not certainly know. it is not likely that they had bony plates like crocodiles, but they may have shone resplendent in horny scale armour of varied hues. but another and more dreadful form rises before us. it is _megalosaurus_ or perhaps _lælaps_. here we have a creature of equally gigantic size and biped habits; but it is much more agile, and runs with great swiftness or advances by huge leaps, and its feet and hands are armed with strong curved claws; while its mouth has a formidable armature of sharp-edged and pointed teeth. it is a type of a group of biped bird-like lizards, the most terrible and formidable of rapacious animals that the earth has ever seen. some of these creatures, in their short deep jaws and heads, resembled the great carnivorous mammals of modern times, while all in the structure of their limbs had a strange and grotesque resemblance to the birds. nearly all naturalists regard them as reptiles; but in their circulation and respiration they must have approached to the mammalia, and their general habit of body recalls that of the kangaroos. they were no doubt oviparous; and this, with their biped habit, seems to explain the strong resemblance of their hind quarters to those of birds. had we seen the eagle-clawed lælaps rushing on his prey; throwing his huge bulk perhaps thirty feet through the air, and crushing to the earth under his gigantic talons some feebler hadrosaur, we should have shudderingly preferred the companionship of modern wolves and tigers to that of those savage and gigantic monsters of the mesozoic. we must not leave the great land-lizards of the reptilian age, without some notice of that goliath of the race which, by a singular misnomer, has received the appellation of _ceteosaurus_ or "whale-saurian." it was first introduced to naturalists by the discovery of a few enormous vertebrae in the english oolite; and as these in size and form seemed best to fit an aquatic creature, it was named in accordance with this view. but subsequent discoveries have shown that, incredible though this at first appeared, the animal had limbs fitted for walking on the land. professor phillips has been most successful in collecting and restoring the remains of ceteosaurus, and devotes to its history a long and interesting section of his "geology of oxford." the size of the animal may be estimated, from the fact that its thigh-bone is sixty-four inches long, and thick in proportion. from this and other fragments of the skeleton, we learn that this huge monster must have stood ten feet high when on all fours, and that its length, could not have been less then fifty feet; perhaps much more. from a single tooth, which has been found, it seems to have been herbivorous; and it was probably a sort of reptilian hippopotamus, living on the rich herbage by the sides of streams and marshes, and perhaps sometimes taking to the water, where the strokes of its powerful tail would enable it to move more rapidly then on the land. in structure, it seems to have been a composite creature, resembling in many points the contemporary dinosaurs; but in others, approaching to the crocodiles and the lizards. but the wonders of mesozoic reptiles are not yet exhausted. while noticing numerous crocodiles and lizard: like creatures, and several kinds of tortoises, we are startled by what seems a flight of great bats, wheeling and screaming overhead, pouncing on smaller creatures of their own kind, as hawks seize sparrows and partridges, and perhaps diving into the sea for fish. these were the pterodactyles, the reptile bats of the mesozoic. they fly by means of a membrane stretched on a monstrously enlarged little finger, while the other fingers of the fore limb are left free to be used as hands or feet. to move these wings, they had large breast-muscles like those of birds. in their general structure, they were lizards, but no doubt of far higher organization then any animals of this order now living; and in accordance with this, the interior of their skull shows that they must have had a brain comparable with that of birds, which, they rivalled in energy and intelligence. some of them were larger then the largest modern birds of prey, others were like pigeons and snipes in size. specimens in the cambridge museum indicate one species twenty feet in the expanse of its wings. cope has recently described an equally gigantic species from the mesozoic of western america, and fragments of much larger species are said to exist.[ae] imagine such a creature, a flying dragon, with vast skinny wings, its body, perhaps, covered with scales, both wings and feet armed with strong claws, and with long jaws furnished with sharp teeth. nothing can be conceived more strange and frightful. some of them had the hind limbs long, like wading birds. some had short, legs, adapted perhaps for perching. they could probably fold up their wings, and walk on all fours. their skeleton, like that of birds, was very light, yet strong; and the hollow bones have pores, which show that, as in birds, air could be introduced into them from the lungs. this proves a circulation resembling that of birds, and warm blood. indeed, in many respects, these creatures bridge over the space between the birds and the reptiles. "that they lived," says seeley, "exclusively upon land or in the air is improbable, considering the circumstances under which their remains are found. it is likely that they haunted the sea-shores; and while sometimes rowing themselves over the water with their powerful wings, used the wing membrane, as does the bat, to encloses the prey and bring it to the mouth. the large pterodactyles probably pursued a more substantial prey then dragon-flies. their teeth were well suited for fish; but probably fowl and small mammal, and even fruits, made a variety in their food. as the lord of the cliff, it may be supposed to have taken toll of all animals that could be conquered with tooth and nail. from its brain, it might be regarded as an intelligent animal. the jaws present indications of having been sheathed with a horny covering, and some species show a rugose anterior termination of the snout, suggestive of fleshy lips like those of the bat, and which may have been similarly used to stretch and clean the wing-membrane." [ae] seeley: "_ornithosauria._" here, however, perched on the trees, we see true birds. at least they have beaks, and are clothed with feathers. but they have very strange wings, the feathers all secondaries, without any large quills, and several fingers with claws at the angle of the wing, so that though less useful as wings, they served the double purpose of wing and hand. more strange still, the tail was long and flexible, like that of a lizard, with the feathers arranged in rows along its sides. if the lizards of this strange and uncertain time had wings like bats, the birds had tails and hands like lizards. this was in short the special age of reptiles, when animals of that class usurped the powers which rightfully belonged to creatures yet in their nonage, the true birds and mammals of our modern days, while the birds were compelled to assume some reptilian traits. yet, strange to say, representatives of the higher creatures destined to inherit the earth at a later date actually existed. toward the close of the mesozoic we find birds approaching to those of our own day, and almost at the beginning of the time there were small mammals, remains of which are found both in the earlier and later formations of the mesozoic, but which never seem to have thriven; at least so far as the introduction of large and important species is concerned. traversing the mesozoic woods, we might see here and there little hairy creatures, which would strike a naturalist as allies of the modern bandicoots, kangaroo rats, and myrmecobius of australia; and closer study would confirm this impression, though showing differences of detail. in their teeth, their size, and general form, and probably in their pouched or marsupial reproduction, these animals were early representatives of the smaller quadrupeds of the austral continent, creatures which are not only small but of low organisation in their class. one of these mammals, known to us only by its teeth, and well named _microlestes_, the "little thief" sneaks into existence, so to speak, in the trias of europe, while another very similar, _dromatherium_, appears in rocks of similar age in america; and this is the small beginning of the great class mammalia, destined in its quadrupedal forms to culminate in the elephants and their contemporaries in the tertiary period. who that saw them trodden under foot lay the reptile aristocracy of the mesozoic could have divined their destiny? but, notwithstanding the struggle for existence, the weakest does not always "go to the wall." the weak things of this world are often chosen to confound those that are mighty; and the little quadrupeds of the mesozoic are an allegory. they may typify the true, the good, and the hopeful, mildly and humbly asserting themselves in the world that now is, in the presence of the dragon monsters of pride and violence, which in the days to come they will overthrow. physically the mesozoic has passed away, but still exists morally in an age of evil reptiles, whose end is as certain as that of the great dinosaurs of the old world. the mesozoic mammals are among the most interesting fossils known to us. in a recent memoir by professor owen, thirty-three species are indicated--all, or nearly all, marsupial--all small--all closely allied to modern australian animals; some herbivorous, some probably carnivorous. owen informs us that these animals are not merely marsupials, but marsupials of low grade, a point in which, however, huxley differs somewhat in opinion. they are at least not lower then some that still exist, and not so low as those lowest of mammals in modern australia, the duck-billed platypus and the echidna. owen further supposes that they were possibly the first mammals, and not only the predecessors but the progenitors of the modern marsupials. if so, we have the singular fact that they not only did not improve throughout the vast mesozoic time, but that they have been in the progress of subsequent geological ages expelled out of the great eastern continent, and, with the exception of the american opossums, banished, like convicts, to australia. yet, notwithstanding their multiplied travels and long experiences, they have made little advance. it thus seems that the mesozoic mammals were, from the evolutionist point of view, a decided failure, and the work of introducing mammals had to be done over again in the tertiary; and then, as we shall find, in a very different way. if nothing more, however, the mesozoic mammals were a mute prophecy of a better time, a protest that the age of reptiles was an imperfect age, and that better things were in store for the world. moses seems to have been more hopeful of them then owen or even huxley would have been. he says that god "created" the great tanninim, the dinosaurs and their allies, but only "made" the mammals of the following creative day; so that when microlestes and his companions quietly and unnoticed presented themselves in the mesozoic, they would appear in some way to have obviated, in the case of the tertiary mammals, the necessity of a repetition of the greater intervention implied in the word "create." how that was effected none of us know; but, perhaps, we may know hereafter. chapter ix. the mesozoic ages (_continued_). the waters of the mesozoic period present features quite as remarkable as the land. in our survey of their teeming multitudes, we indeed scarcely know where to begin or whither to turn. let us look first at the higher or more noble inhabitants of the waters. and here, just as in the case of the greater animals of the land, the mesozoic was emphatically an age of reptiles. in the modern world the highest animals the sea are mammals, and these belong to three great and somewhat diverse groups. the first is that of the seals and their allies, the walruses, sea-lions, etc. the second is that of the whales and dolphins and porpoises. the third is that of the manatees, or dugongs. all these creatures breathe air, and bring forth their young alive, and nourish them with milk. yet they all live habitually or constantly in the water. between these aquatic mammals and the fishes, we have some aquatic reptiles as the turtles, and a few sea-snakes and sea-lizards, and crocodiles; but the number of these is comparatively small, and in the more temperate latitudes there are scarcely any of them. all this was different in the mesozoic. in so far as we know, there were no representatives of the seals and whales and their allies, but there were vast numbers of marine reptiles, and many of these of gigantic size. britain at present does not possess one large reptile, and no marine reptile whatever. in the mesozoic, in addition to the great dinosaurs and pterodactyls of the land, it had at least fifty or sixty species of aquatic reptiles, besides many turtles. some of these were comparable in size with our modern whales, and armed with tremendous powers of destruction. america is not relatively rich in remains of mesozoic saurians, yet while the existing fauna of the temperate parts of north america is nearly destitute of aquatic reptiles, with the exception of the turtles, it can boast, according to cope's lists, about fifty mesozoic species, many of them of gigantic size, and the number of known species is increasing every year when it is taken in connection with these statistics, that while we know all the modern species, we know but a small percentage of the fossils, the discrepancy becomes still more startling. further, from the number of specimens and fragments found, it is obvious that these great aquatic saurians were by no means rare; and that some of the species at least must have been very abundant. could we have taken our post on the mesozoic shore, or sailed over its waters, we should have found ourselves in the midst of swarms of these strange, often hideous, and always grotesque creatures. let us consider for a little some of the more conspicuous forms, referring to our illustration for their portraits. every text-book figures the well-known types of the genera _ichthyosaurus_ and _plesiosaurus_; we need scarcely, therefore, dwell on them, except to state that the catalogues of british fossils include eleven species of the former genus and eighteen of the latter, we may, however, notice some of the less familiar points of comparison of the two genera. both were aquatic, and probably marine. both swam by means of paddles; both were carnivorous, and probably fed principally upon fishes; both were proper reptiles, and breathed air, and had large and capacious lungs. yet with these points in common, no two animals could have been more different in detail. the ichthyosaurus had an enormous head, with powerful jaws, furnished with numerous and strong teeth. its great eyes, strengthened by a circle of bony plates, exceeded in dimensions, and probably in power of vision under water, those of any other animal, recent or fossil. its neck was short, its trunk massive, with paddles or swimming limbs of comparatively small size, and a long tail, probably furnished with a caudal fin or paddle for propulsion through the water. the plesiosaur, on the other hand, had a small and delicate head, with slender teeth and small eyes. its neck, of great length and with numerous joints, resembled the body of a serpent. its trunk, short, compact, and inflexible, was furnished with large and strong paddles, and its tail was too short to be of any service except for steering. compared with the ichthyosaur, it was what the giraffe is to the rhinoceros, or the swan to the porpoise. two fishermen so variously and differently fitted for their work it would be difficult to imagine. but these differences were obviously related to corresponding differences in food and habit. the ichthyosaur was fitted to struggle with the waves of the stormy sea, to roll therein like modern whales and grampuses, to seize and devour great fishes, and to dive for them into the depths; and its great armour-plated eyes must have been well adapted for vision in the deeper waters. the plesiosaur, on the contrary, was fitted for comparatively still and shallow waters; swimming near the surface with its graceful neck curving aloft, it could dart at the smaller fishes on the surface, or stretch its long neck downward in search of those near the bottom. the ichthyosaurs rolled like porpoises in the surf of the liassic coral reefs and the waves beyond; the plesiosaurs careered gracefully in the quiet waters within. both had their beginning at the same time in the earlier mesozoic, and both found a common and final grave in its later sediments. some of the species were of very moderate size, but there were ichthyosaurs twenty five feet long, and plesiosaurs at least eighteen feet in length. another strange and monstrous group of creatures, the elasmosaurs and their allies, combined the long neck of plesiosaurs with the swimming tail of ichthyosaurs, the latter enormously elongated, so that these creatures were sometimes fifty feet in length, and whale-like in the dimensions of their bodies. it is curious that these composite creatures belong to a later period of the mesozoic then the typical ichthyosaurs and plesiosaurs, as if the characters at one time separated in these genera had united in their successors. one of the relatives of the plesiosaurs, the pliosaur, of which genus several species of great size are known perhaps realized in the highest degree possible the idea of a huge marine predaceous reptile. the head in some of the species was eight feet in length, armed with conical teeth a foot long. the neck was not only long, but massive and powerful, the paddles, four in number, were six or seven feet in length and must have urged the vast bulk of the animal, perhaps forty feet in extent, through the water with prodigious speed. the capacious chest and great ribs show a powerful heart and lungs. imagine such a creature raising its huge head twelve feet or more out of water, and rushing after its prey, impelled with perhaps the most powerful oars ever possessed by any animal. we may be thankful that such monsters, more terrible then even the fabled sea-serpent, are unknown in our days. buckland, i think, at one time indulged in the _jeu d'esprit_ of supposing an ichthyosaur lecturing on the human skull. "you will at once perceive," said the lecturer, "that the skull before us belonged to one of the lower orders of animals. the teeth are very insignificant, the power of the jaws trifling, and altogether it seems wonderful how the creature could have procured food." we cannot retort on the ichthyosaur and his contemporaries, for we can see that they were admirably fitted for the work they had in hand; but we can see that had man been so unfortunate as to have lived in their days, he might have been anything but the lord of creation. but there were sea-serpents as well as other monsters in the mesozoic seas. many years ago the lower cretaceous beds of st. peter's mount, near maestricht, afforded a skull three feet in length, of massive proportions, and furnished with strong conical teeth, to which the name _mosasaurus camperi_ was given. the skull and other parts of the skeleton found with it, were held to indicate a large aquatic reptile, but its precise position in its class was long a subject of dispute. faujas held it to be a crocodile; camper, cuvier, and owen regarded it as a gigantic lizard. more recently, additional specimens, especially those found in the cretaceous formations of north america, have thrown new light upon its structure, and have shown it to present a singular combination of the character of serpents, lizards, and of the great sea saurians already referred to. some parts of the head and the articulation of the jaws, in important points resemble those of serpents, while in other respects the head is that of a gigantic lizard. the body and tail are greatly lengthened out, having more then a hundred vertebral joints, and in one of the larger species attaining the length of eighty feet. the trunk itself is much elongated, and with ribs like those of a snake. there are no walking feet, but a pair of fins or paddles like those of ichthyosaurus. cope, who has described these great creatures as they occur in the cretaceous of the united states, thus sketches the mosasaur: "it was a long and slender reptile, with a pair of powerful paddles in front, a moderately long neck, and flat pointed head. the very long tail was flat and deep, like that of a great eel, forming a powerful propeller. the arches of the vertebral column were more extensively interlocked then in any other reptiles except the snakes. in the related genus _clidastes_ this structure is as fully developed as in the serpents, so that we can picture to ourselves its well-known consequences; their rapid progress through the water by lateral undulations, their lithe motions on the land, the rapid stroke, the ready coil, or the elevation of the head and vertebral column, literally a living pillar, towering above the waves or the thickets of the shore swamps." as in serpents, the mouth was wide in its gape, and the lower jaw capable of a certain separation from the skull to admit of swallowing large prey. besides this the lower jaw had an additional peculiarity, seen in some snakes, namely, a joint in the middle of the jaw enabling its sides to expand, so that the food might be swallowed "between the branches of the jaw." perhaps no creatures more fully realize in their enormous length and terrible powers the great tanninim (the stretched-out or extended reptiles) of the fifth day of the mosaic record, then the mosasaurus and elasmosaurus. when mr. cope showed me, a few years ago, a nearly complete skeleton of elasmosaurus, which for want of space he had stretched on a gallery along two sides of a large room, i could not help suggesting to him that the name of the creature should be _teinosaurus_[af] instead of that which he had given. marsh has recently ascertained that the mosasaurs were covered in part at least with bony scales. [af] heb. _tanan_; gr. _teino_, _tanuo_; sansc. _tanu_; lat. _tendo_.--ges. lex. [illustration: life in the mesozoic period. aquatic reptiles and cephalopods. _reptiles._--plesiosaur and osteopygis, ichthyosaur, teliosaur, plesiosaur, elasmosaur, mosasaur (in order of the heads from left to right).--_cephalopods._--ammonite, crioceras, belemnites, baculites, and ammonites (in order from left to right). the reptiles after hawkins and cope's restorations.] these animals may serve as specimens of the reptilian giants of the mesozoic seas; but before leaving them we must at least invite attention to the remarkable fact that they were contemporary with species which represent the more common aquatic reptiles of the modern world. in other words, the monsters which we have described existed over and above a far more abundant population of crocodiles and turtles then the modern waters can boast. the crocodiles were represented both in europe and america by numerous and large species, most of them with long snouts like the modern gavials, a few with broad heads like those of the alligators. the turtles again presented not only many species, but most of the aquatic subdivisions of the group known in modern times, as for instance the emydes or ordinary fresh-water forms, the snapping turtles, and the soft-shelled turtles. cope says that the cretaceous of new jersey alone affords twenty species, one of them a snapping turtle six feet in length. owen records above a dozen large species from the upper mesozoic of england, and dates the first appearance of the turtles in england about the time of the portland stone, or in the upper half of the mesozoic; but footprints supposed to be those of turtles are found as far back as the trias. perhaps no type of modern reptiles is more curiously specialized then these animals, yet we thus find them contemporaneous with many generalized types, and entering into existence perhaps as soon as they. the turtles did not culminate in the mesozoic, but go on to be represented by more numerous and larger species in the tertiary and modern. in the case of the crocodiles, while they attained perhaps a maximum toward the end of the mesozoic, it was in a peculiar form. the crocodiles of this old time had vertebrae with a hollow at each end like the fishes, or with a projection in the front. at the end of the mesozoic this was changed, and they assumed a better-knit back, with joints having a ball behind and a socket in front. in the cretaceous age, species having these two kinds of backbone were contemporaneous. perhaps this improvement in the crocodilian back had something to do with the persistence of this type after so many others of the sea-lizards of the mesozoic had passed away. of the fishes of the mesozoic we need only say that they were very abundant, and consisted of sharks and ganoids of various types, until near the close of the period, when the ordinary horny-scaled fishes, such as abound in our present seas, appear to have been introduced. one curious point of difference is that the unequally lobed tail of the palæozoic fishes is dropped in the case of the greater part of the ganoids, and replaced by the squarely-cut tail prevalent in modern times. in the sub-kingdom of the mollusca many important revolutions occurred. among the lamp-shells a little _leptaena_, no bigger then a pea, is the last and depauperated representative of a great palæozoic family. another, that of the spirifers, still shows a few species in the lower mesozoic. others, like rhynchonella, and terebratula, continue through the period, and extend into the modern. passing over the ordinary bivalves and sea-snails, which in the main conform to those of our own time, we find perhaps the most wonderful changes among the relatives of the cuttle-fishes and nautili. as far back as the silurian we find the giant orthoceratites contemporary with nautili, very like those of the present ocean. with the close of the palæozoic, however, the orthoceratites and their allies disappear, while the nautili continue, and are reinforced by multitudes of new forms of spiral chambered shells, some of them more wonderful and beautiful then any of those which either preceded or followed them. supreme among these is the great group of the _ammonites_,--beautifully spiral shells, thin and pearly like the nautilus, and chambered like it, so as to serve as a float, but far more elaborately constructed, inasmuch as the chambers were not simply curved, but crimped and convoluted, so as to give the outer wall much more effectual support. this outer wall, too, was worked into ornamental ribs and bands, which not only gave it exquisite beauty, but contributed to combine strength to resist pressure with the lightness necessary to a float. in some of these points it is true the gyroceras and goniatites of the palæozoic partially anticipated them, but much less perfectly. the animals which inhabited these shells must have been similar to that of nautilus, but somewhat different in the proportion of parts. they must have had the same power of rising and sinking in the water, but the mechanical construction of their shells was so much more perfect relatively to this end, that they were probably more active and locomotive then the nautili. they must have swarmed in the mesozoic seas, some beds of limestone and shale being filled with them; and as many as eight hundred species of this family are believed to be known, including, however, such forms as the _baculites_ or straight ammonites, bearing to them perhaps a relation similar to that of orthoceras to nautilus. further, some of the ammonites are of gigantic size, one species being three feet in diameter, while others are very minute. the whole family of ammonitids, which begins to be in force in the trias, disappears at the end of the mesozoic, so that this may be called the special age of ammonites as well as of reptiles. further, this time was likewise distinguished by the introduction of true cuttle-fishes, the most remarkable of which were those furnished with the internal supports or "bones," known as _belemnites_, from a fancied resemblance to javelins or thunder-bolts, a comparison at least as baseless as that often made in england of the ammonites to fossil snakes. the shell of the belemnite is a most curious structure. its usual general shape is a pointed cylinder or elongated cone. at top it has a deep cavity for the reception of certain of the viscera of the animal. below this is a conical series of chambers, the phragmacone; and the lower half of the shell is composed of a solid shelly mass or guard, which, in its structure of radiating fibres and concentric layers, resembles a stalactite, or a petrified piece of exogenous wood. this structure was an internal shell or support like those of the modern cuttle-fishes; but it is difficult to account for its peculiarities, so much more complex then in any existing species. the most rational supposition seems to be that it was intended to serve the triple purpose of a support, a float, and a sinker. unlike the shell of a nautilus, if thrown into the water it would no doubt have, sunk, and with the pointed end first. consequently, it was not a float simply, but a float and sinker combined, and its effect must have been to keep the animal at the bottom, with its head upward. the belemnite was therefore an exceptional cuttle-fish, intended to stand erect on the sea-bottom and probably to dart upward in search of its prey; for the suckers and hooks with which its arms were furnished show that, like other cuttle-fishes, it was carnivorous and predaceous. the guard may have been less ponderous when recent then in the fossil specimens, and in some species it was of small size or slender, and in others it was hollow. possibly, also, the soft tissues of the animal were not dense, and it may have had swimming fins at the sides. in any case they must have been active creatures, and no doubt could dart backward by expelling water from their gill chamber, while we know that they had ink-bags, provided with that wonderfully divided pigment, inimitable by art, with which the modern sepia darkens the water to shelter itself from its enemies. the belemnites must have swarmed in the mesozoic seas; and as squids and cuttles now afford choice morsels to the larger fishes, so did the belemnites in their day. there is evidence that even the great sea-lizards did not disdain to feed on them. we can imagine a great shoal of these creatures darting up and down, seizing with their ten hooked arms their finny or crustacean prey. in an instant a great fish or saurian darts down among them; they blacken the water with a thick cloud of inky secretion and disperse on all sides, while their enemy, blindly seizing a few mouthfuls, returns sullenly to the surface. a great number of species of belemnites and allied animals have been described; but it is probable that in naming them too little regard has been paid to distinctions of age and sex. the belemnites were for the most part small creatures; but there is evidence that there existed with them some larger and more formidable cuttles; and it is worthy of note that, in several of these, the arms, as in the belemnites, were furnished with hooks as well as suckers, an exceptional arrangement in their modern allies. it is probable that while the four-gilled or shell-bearing cuttles culminated in size and perfection in the ammonitids of the mesozoic, the modern cuttles of the two-gilled and shell-less type are grander in dimensions then their mesozoic predecessors. it is, however, not a little singular that a group so peculiar and apparently so well provided with means, both of offence and defence, as the belemnites, should come in and go out with the mesozoic, and that the nautiloid group, after attaining to the magnitude and complexity of the great ammonites, should retreat to a few species of diminutive and simply-constructed nautili; and in doing so should return to one of the old types dating as far back as the older palæozoic, and continuing unchanged through all the intervening time. the crustaceans of the mesozoic had lost all the antique peculiarities of the older time, and had so much of the aspect of those of the present day, that an ordinary observer, if he could be shown a quantity of jurassic or cretaceous crabs, lobsters, and shrimps, would not readily recognise the difference, which did not exceed what occurs in distant geographical regions in the present day. the same remark may be made as to the corals of the mesozoic; and with some limitations, as to the star-fishes and sea-urchins, which latter are especially numerous and varied in the cretaceous age. in short, all the invertebrate forms of life, and the fishes and reptiles among the vertebrates, had already attained their maximum elevation in the mesozoic; and some of them have subsequently sunk considerably in absolute as well as relative importance. in the course of the mesozoic, as indicated in the last chapter, there had been several great depressions and re-elevations of the continental areas. but these had been of the same quiet and partial character with those of the palæozoic, and it was not until the close of the mesozoic time, in the cretaceous age, that a great and exceptional subsidence involved for a long period the areas of our present continents in a submergence wider and deeper then any that had previously occurred since the dry land first rose out of the waters. every one knows the great chalk beds which appear in the south of england, and which have given its name to the latest age of the mesozoic. this great deposit of light-coloured and usually soft calcareous matter attains in some places to the enormous thickness of , feet. nor is it limited in extent. according to lyell, its european distribution is from ireland to the crimea, a distance of , geographical miles; and from the south of france to sweden, a distance of geographical miles. similar rocks, though not in all cases of the precise nature of chalk, occur extensively in asia and in africa, and also in north and south america. but what is chalk? it was, though one of the most familiar, one of the most inscrutable of rocks, until the microscope revealed its structure. the softer varieties, gently grated or kneaded down in water, or the harder varieties cut in thin slices, show a congeries of microscopic chambered shells belonging to the humble and simple group of protozoa. these shells and their fragments constitute the material of the ordinary chalk. with these are numerous spicules of sponges and silicious cell-walls of the minute one-celled plants called diatoms. further, the flinty matter of these organisms has by the law of molecular attraction been collected into concretions, which are the flints of the chalk. such a rock is necessarily oceanic; but more then this, it is abyssal. laborious dredging has shown that similar matter is now being formed only in the deep bed of the ocean, whither no sand or mud is drifted from the land, and where the countless hosts of microscopic shell-bearing protozoa continually drop their little skeletons on the bottom, slowly accumulating a chalky mud or slime. that such a rock should occur over vast areas of the continental plateaus, that both in europe and america it should be found to cover the tops of hills several thousand feet high, and that its thickness should amount to several hundreds of feet, are facts which evidence a revolution more stupendous perhaps then that at the close of the palæozoic. for the first time since the laurentian, the great continental plateaus changed places with the abysses of the ocean, and the successors of the laurentian eozoon again reigned on surfaces which through the whole lapse of palæozoic and mesozoic time had been separated more or less from that deep ocean out of which they rose at first. this great cretaceous subsidence was different from the disturbances of the permian age. there was at first no crumpling of the crust, but merely a slow and long-continued sinking of the land areas, followed, however, by crumpling of the most stupendous character, which led at the close of the cretaceous and in the earlier tertiary to the formation of what are now the greatest mountain chains in the world. as examples may be mentioned the himalaya, the andes, and the alps, on all which the deep-sea beds of the cretaceous are seen at great elevations. in europe this depression was almost universal, only very limited areas remaining out of water. in america a large tract remained above water in the region of the appalachians. this gives us some clue to the phenomena. the great permian collapse led to the crumpling-up of the appalachians and the urals, and the older hills of western europe. the cretaceous collapse led to the crumpling of the great n.w. and s.e. chain of the rocky mountains and andes, and to that of the east and west chains of the south of asia and europe. the cause was probably in both cases the same; but the crust gave way in a different part, and owing to this there was a greater amount of submergence of our familiar continental plateaus in the cretaceous then in the permian. another remarkable indication of the nature of the cretaceous subsidence, is the occurrence of beds filled with grains of the mineral glauconite or "green-sand." these grains are not properly sand, but little concretions, which form in the bottom of the deep sea, often filling and taking casts of the interior and fine tubes of foraminiferal shells. now this glauconite, a hydrous silicate of iron and potash, is akin to similar materials found filling the pores of fossils in silurian beds. it is also akin to the serpentine filling the pores of eozoon in the laurentian. such materials are formed only in the deeper parts of the ocean, and apparently most abundantly where currents of warm water are flowing at the surface, as in the area of the gulf stream. thus, not only in the prevalence of foraminifera, but in the formation of hydrous silicates, does the cretaceous recall the laurentian. such materials had no doubt been forming, and such animals living in the ocean depths, all through the intervening ages, but with the exception of a few and merely local instances, we know nothing of them, till the great subsidence and re-elevation of the cretaceous again allows them to ascend to the continental plateaus, and again introduces us to this branch of the world-making process. the attention recently drawn to these facts by the researches of dr. carpenter and others, and especially the similarity in mineral character and organic remains of some of the deposits now forming in the atlantic and those of the chalk, have caused it to be affirmed that in the bed of the atlantic these conditions of life and deposit have continued from the cretaceous up to the present time, or as it has been expressed, that "we are still living in the cretaceous epoch." now, this is true or false just as we apply the statement. we have seen that the distinction between abyssal areas, continental oceanic plateaus, and land surfaces has extended through the whole lapse of geological time. in this broad sense we may be said to be still living in the laurentian epoch. in other words, the whole plan of the earth's development is one and the same, and each class of general condition once introduced is permanent somewhere. but in another important sense we are not living in the cretaceous epoch; otherwise the present site of london would be a thousand fathoms deep in the ocean; the ichthyosaurs and ammonites would be disporting themselves in the water, and the huge dinosaurs and strange pterodactyls living on the land. the italian peasant is still in many important points living in the period of the old roman empire. the arab of the desert remains in the patriarchal period, and there are some tribes not yet beyond the primitive age of stone. but the world moves, nevertheless, and the era of victoria is not that of the plantagenets or of julius cæsar. so while we may admit that certain of the conditions of the cretaceous seas still prevail in the bed of the present ocean, we must maintain that nearly all else is changed, and that the very existence of the partial similarity is of itself the most conclusive proof of the general want of resemblance, and of the thorough character of the changes which have occurred. the duration of the cretaceous subsidence must have been very great. we do not know the rate at which the foraminifera accumulate calcareous mud. in some places, where currents heap up their shells, they may be gathered rapidly; but on the average of the ocean bed, afoot of such material must indicate the lapse of ages very long when compared with those of modern history. we need not wonder, therefore, that while some forms of deep-sea cretaceous life, especially of the lower grades, seem to have continued to our time, the inhabitants of the shallow waters and the land have perished; and that the neozoic or tertiary period introduces us to a new world of living beings. i say we need not wonder; yet there is no reason why we should expect this as a necessary consequence. as the cretaceous deluge rose over the continents of the mesozoic, the great sea saurians might have followed. those of the land might have retreated to the tracts still remaining out of water, and when the dry land again appeared in the earlier tertiary, they might again have replenished the earth, and we might thus have truly been living in the reptilian age up to this day. but it was not so. the old world again perished, and the dawn of the tertiary shows to us at once the dynasties of the mammalian age, which was to culminate in the introduction of man. with the great cretaceous subsidence the curtain falls upon the age of reptiles, and when it rises again, after the vast interval occupied in the deposition of the green-sand and chalk, the scene has entirely changed. there are new mountains and new plains, forests of different type, and animals such as no previous age had seen. how strange and inexplicable is this perishing of types in the geological ages! some we could well spare. we would not wish to have our coasts infested by terrible sea saurians, or our forests by carnivorous dinosaurs. yet why should these tyrants of creation so utterly disappear without waiting for us to make war on them? other types we mourn. how glorious would the hundreds of species of ammonites have shone in the cases of our museums, had they still lived! what images of beauty would they have afforded to the poets who have made so much of the comparatively humble nautilus! how perfectly, too, were they furnished with all those mechanical appliances for their ocean life, which are bestowed only with a niggardly hand on their successors! nature gives us no explanation of the mystery. "from scarped cliff and quarried stone, she cries--'a thousand types are gone.'" but why or how one was taken and another left she is silent, and i believe must continue to be so, because the causes, whether efficient or final, are beyond her sphere. if we wish for a full explanation, we must leave nature, and ascend to the higher domain of the spiritual. condensed tabular view of the ages and periods of the mesozoic. key to symbols ### duration of ammonites and belemnites. === ages of cycads and pines. --- beginning of age of angiospermous exogens. +++ "and god created great reptiles, and every living moving thing which the waters brought forth abundantly, and every flying creature after its kind." time. ages. periods. animals and plants. mesozoic. cretaceous {newer.{maestricht beds; fox hill # - + { {and pierre groups of # - + { {western america; greensand # - + { {of new jersey. # - + { # - + {middle.{chalk; benton and dakota # close of - + { {groups of western america. # reptilian - + { # ages. - + {older.{lower greensand and gault; # - + { {lower clays of new jersey # + { {and alabama. # + # + upper {n. purbeck beds. }jurassic # culmination + jurassic {m. portland limestone. } beds of # of + {o. portland sandstone. }nebraska # reptilian + } and # ages. + middle {n. kimmeridge clay, etc.}colorado.# = + jurassic {m. coralline limestone. } # = + {o. calcareous grit & } # = + { oxford clay. } # = + # = + lower {n. cornbrash & forest } lower # = + jurassic { marble. }jurassic # = + {m. great & inferior } of # = + { oolites., etc. } utah, # = + {o. lias clay and }nevada, # = + { limestone. } etc. = + = + {n. keuper {upper triassic appearance of = + { sandstone, {sandstones of mammals = + { etc. {prince edward i., and = + {m. muschelkalk.{connecticut, etc. birds. + triassic { + {o. bunter {lower triassic beginning of + { sandstone. {sandstones of reptilian + { {prince edward i., ages. + { {connecticut, etc. + chapter x. the neozoic ages. between the mesozoic and the next succeeding time which may be known as the neozoic or tertiary,[ag] there is in the arrangements of most geologists a great break in the succession of life; and undoubtedly the widespread and deep subsidence of the cretaceous, followed by the elevation of land on a great scale at the beginning of the next period, is a physical cause sufficient to account for vast life changes. yet we must not forget to consider that even in the cretaceous itself there were new features beginning to appear. let us note in this way, in the first place, the introduction of the familiar generic forms of exogenous trees. next we may mention the decided prevalence of the modern types of coral animals and of a great number of modern generic forms of mollusks. then we have the establishment of the modern tribes of lobsters and crabs, and the appearance of nearly all the orders of insects. among vertebrates, the ordinary fishes are now introduced. modern orders of reptiles, as the crocodiles and chelonians, had already appeared, and the first mammals. henceforth the progress of organic nature lies chiefly in the dropping of many mesozoic forms and in the introduction of the higher tribes of mammals and of man. [ag] the former name is related to palæozoic and mesozoic, the latter to the older terms primary and secondary. for the sake of euphony we shall use both. the term neozoic was proposed by edward forbes for the mesozoic and cainozoic combined; but i use it here as a more euphonious and accurate term for the cainozoic alone. it is further to be observed that the new things introduced in the later mesozoic came in little by little in the progress of the period, and anticipated the great physical changes occurring at its close. on the other hand, while many family and even generic types pass over from the mesozoic to the earlier tertiary, very few species do so. it would seem, therefore, as if changes of species were more strictly subordinate to physical revolutions then were changes of genera and orders--these last overriding under different specific forms many minor vicissitudes, and only in part being overwhelmed in the grander revolutions of the earth. both in europe and america there is evidence of great changes of level at the beginning of the tertiary. in the west of europe beds often of shallow-water or even fresh-water origin fill the hollows in the bent cretaceous strata. this is manifestly the case with the formations of the london and paris basins, contemporaneous but detached deposits of the tertiary age, lying in depressions of the chalk. still this does not imply much want of conformity, and according to the best explorers of those alpine regions in which both the mesozoic and tertiary beds have been thrown up to great elevations, they are in the main conformable to one another. something of the same kind occurs in america. on the atlantic coast the marine beds of the older tertiary cover the cretaceous, and little elevation seems to have occurred farther west the elevation increases, and in the upper part of the valley of the mississippi it amounts to feet. still farther west, in the region of the rocky mountains, there is evidence of elevation to the extent of as much as feet. throughout all these regions scarcely any disturbance of the old cretaceous sea-bottom seems to have occurred until after the deposition of the older tertiary, so that there was first a slow and general elevation of the cretaceous ocean bottom, succeeded by gigantic folds and fractures, and extensive extravasations of the bowels of the earth in molten rocks, in the course of the succeeding tertiary age. these great physical changes inaugurated the new and higher life of the tertiary, just as the similar changes in the permian did that of the mesozoic. the beginning of these movements consisted of a great and gradual elevation of the northern parts of both the old and new continents out of the sea, whereby a much greater land surface was produced, and such changes of depth and direction of currents in the ocean as must have very much modified the conditions of marine life. the effect of all these changes in the aggregate was to cause a more varied and variable climate, and to convert vast areas previously tenanted by marine animals into the abodes of animals and plants of the land, and of estuaries, lakes, and shallow waters. still, however, very large areas now continental were under the sea. as the tertiary period advanced, these latter areas were elevated, and in many cases were folded up into high mountains. this produced further changes of climate and habitat of animals, and finally brought our continents into all the variety of surface which they now present, and which fits them so well for the habitation of the higher animals and of man. the thoughtful reader will observe that it follows from the above statements that the partial distribution and diversity in different localities which apply to the deposits of such ages as the permian and the trias apply also to the earlier tertiary; and as the continents, notwithstanding some dips under water, have retained their present forms since the beginning of the tertiary, it follows that these beds are more definitely related to existing geographical conditions then are those of the older periods, and that the more extensive marine deposits of the tertiary are, to a great extent, unknown to us. this has naturally led to some difficulty in the classification of neozoic deposits--those of some of the tertiary ages being very patchy and irregular, while others spread very widely. in consequence of this, sir charles lyell, to whom we owe very much of our definite knowledge of this period, has proposed a subdivision based on the percentage of recent and fossil animals. in other words, he takes it for granted that a deposit which contains more numerous species of animals still living then another, may be judged on that account to be more recent. such a mode of estimation is, no doubt, to some extent arbitrary; but in the main, when it can be tested by the superposition of deposits, it has proved itself reliable. further, it brings before us this remarkable fact, that while in the older periods all the animals whose remains we find are extinct as species, so soon as we enter on the neozoic we find some which still continue to our time--at first only a very few, but in later and later beds in gradually increasing percentage, till the fossil and extinct wholly disappear in the recent and living. the lyellian classification of the tertiary will therefore stand as in the following table, bearing in mind that the percentage of fossils is taken from marine forms, and mainly from mollusks, and that the system has in some cases been modified by stratigraphical evidence:-- { post-pliocene, including that which immediately { precedes the modern. in this the shells, etc., { are recent, the mammalia in part extinct. { { pliocene, or more recent age. in this the { majority of shells found are recent in the tertiary, or { upper beds. in the lower beds the extinct neozoic time. { become predominant. { { miocene, or less recent. in this the large { majority of shells found are extinct. { { eocene, the dawn of the recent. in this only { a few recent shells occur. if we attempt to divide the tertiary time into ages corresponding to those of the older times, we are met by the difficulty that as the continents have retained their present forms and characters to a great extent throughout this time, we fail to find those evidences of long-continued submergences of the whole continental plateaus, or very large portions of them, which we have found so very valuable in the palæozoic and mesozoic. in the eocene, however, we shall discover one very instructive case in the great nummulitic limestone. in the miocene and pliocene the oscillations seem to have been slight and partial. in the post-pliocene we have the great subsidence of the glacial drift; but that seems to have been a comparatively rapid dip, though of long duration when measured by human history; not allowing time for the formation of great limestones, but only of fossiliferous sands and clays, which require comparatively short time for their deposition if then we ask as to the duration of the neozoic, i answer that we have not a definite measure of its ages, if it had any; and that it is possible that the neozoic may have as yet had but one age, which closed with the great drift period, and that we are now only in the beginning of its second age. some geologists, impressed with this comparative shortness of the tertiary, connect it with mesozoic, grouping both together. this, however, is obviously unnatural. the mesozoic time certainly terminated with the cretaceous, and what follows belongs to a distinct aeon. but we must now try to paint the character of this new and peculiar time; and this may perhaps be best done in the following sketches: . the seas of the eocene. . mammals from the eocene to the modern. . tertiary floras. . the glacial period. . the advent of man. the great elevation of the continents which closed the cretaceous was followed by a partial and unequal subsidence, affecting principally the more southern parts of the land of the northern hemisphere. thus, a wide sea area stretched across all the south of europe and asia, and separated the northern part of north america from what of land existed in the southern hemisphere. this is the age of the great nummulitic limestones of europe, africa, and asia, and the orbitoidal limestones of north america. the names are derived from the prevalence of certain forms of those humble shell-bearing protozoa which we first met with in the laurentian, and which we have found to be instrumental in building up the chalk, the _foraminifera_ of zoologists. (fig. p. .) but in the eocene the species of the chalk were replaced by certain broad flat forms, the appearance of which is expressed by the term nummulite, or money-stone; the rock appearing to be made up of fossils, somewhat resembling shillings, sixpences, or three-penny pieces, according to the size of the shells, each of which includes a vast number of small concentric chambers, which during life were filled with the soft jelly of the animal. the nummulite limestone was undoubtedly oceanic, and the other shells contained in it are marine species. after what we have already seen we do not need this limestone to convince us of the continent-building powers of the oceanic protozoa; but the distribution of these limestones, and the elevation which they attain, furnish the most striking proofs that we can imagine of the changes which the earth's crust has undergone in times geologically modern, and also of the extreme newness of man and his works. large portions of those countries which constitute the earliest seats of man in southern europe, northern africa, and western and southern asia, are built upon the old nummulitic sea-bottom. the egyptians and many other ancient nations quarried it for their oldest buildings. in some of these regions it attains a thickness of several thousand feet, evidencing a lapse of time in its accumulation equal to that implied in the chalk itself. in the swiss alps it reaches a height above the sea of , feet, and it enters largely into the structure of the carpathians and pyrenees. in thibet it has been observed at an elevation of , feet above the sea. thus we learn that at a time no more geologically remote then the eocene tertiary, lands now of this great elevation were in the bottom of the deep sea; and this not merely for a little time, but during a time sufficient for the slow accumulation of hundreds of feet of rock, made up of the shells of successive generations of animals. if geology presented to us no other revelation then this one fact, it would alone constitute one of the most stupendous pictures in physical geography which could be presented to the imagination. i beg leave here to present to the reader a little illustration of the limestone-making foraminifera of the cretaceous and eocene seas. in the middle above is a nummulite of the natural size. below is another, sliced to show its internal chambers. at one side is a magnified section of the common building stone of paris, the milioline limestone of the eocene, so called from its immense abundance of microscopic shells of the genus miliolina. at the other side is a magnified section of one of the harder varieties of chalk, ground so thin as to become transparent,[ah] and mounted in canada balsam. it shows many microscopic chambered shells of foraminifera. these may serve as illustrations of the functions of these humble inhabitants of the sea as accumulators of calcareous matter. it is further interesting to remark that some of the beds of nummulitic limestone are so completely filled with these shells, that we might from detached specimens suppose that they belonged to sea-bottoms whereon no other form of life was present. yet some beds of this age are remarkably rich in other fossils. lyell states that as many as six hundred species of shells have been found in the principal limestone of the paris basin alone; and the lower eocene beds afford remains of fishes, of reptiles, of birds, and of mammals. among the latter are the bones of gigantic whales, of which one of the most remarkable is the zeuglodon of alabama, a creature sometimes seventy feet in length, and which replaces in the tertiary the great elasmosaurs and ichthyosaurs of the mesozoic, marking the advent, even in the sea, of the age of mammals as distinguished from the age of reptiles. [ah] as for instance that of the giant's causeway, antrim. [illustration: foraminiferal rock-builders. a. nummulites lævigata--eocene. b. the same, showing chambered interior. c. milioline limestone, magnified--eocene, paris. d. hard chalk, section magnified--cretaceous.] this fact leads us naturally to consider in the second place the mammalia, and other land animals of the tertiary. at the beginning of the period we meet with that higher group of mammals, not pouched, which now prevails. among the oldest of these tertiary beasts are _coryphodon_, an animal related to the modern tapirs, and _arctocyon_, a creature related to the bears and racoons. these animals represent respectively the pachyderms, or thick-skinned mammals, and the ordinary carnivora. contemporary with or shortly succeeding these, were species representing the rodents, or gnawing animals, and many other creatures of the group pachydermata, allied to the modern tapirs and hogs, as well as several additional carnivorous quadrupeds. thus at the very beginning of the tertiary period we enter on the age of mammals, it may be well, however, to take these animals somewhat in chronological order. if the old egyptian, by quarrying the nummulite limestone, bore unconscious testimony to the recent origin of man (whose remains are wholly absent from the tertiary deposits), so did the ancient britons and gauls, when they laid the first rude foundations of future capitals on the banks of the themes and of the seine. both cities lie in basins of eocene tertiary, occupying hollows in the chalk. under london there is principally a thick bed of clay, the "london clay" attaining a thickness of five hundred feet. this bed is obviously marine, containing numerous species of sea shells; but it must have been deposited near land, as it also holds many fossil fruits and other remains of plants to which we shall refer in the sequel, and the bones of several species of large animals. among these the old reptiles of the mesozoic are represented by the vertebrae of a supposed "sea snake" (palæophis) thirteen feet long, and species of crocodile allied both to the alligators and the gavials. but besides these there are bones of several animals allied to the hog and tapir, and also a species of opossum, these remains must be drift carcases from neighbouring shores, and they show first the elevation of the old deep-sea bottom represented by the chalk, so that part of it became dry land; next, the peopling of that land by tribes of animals and plants unknown to the mesozoic; and lastly, that a warm climate must have existed, enabling england at this time to support many types of animals and plants now proper to intertropical regions. as lyell well remarks, it is most interesting to observe that these beds belong to the beginning of the tertiary, that they are older then those great nummulite limestones to which we have referred, and that they are older then the principal mountain chains of europe and asia. they show that no sooner was the cretaceous sea dried from off the new land, then there were abundance of animals and plants ready to occupy it, and these not the survivors of the flora and fauna of the wealden, but a new creation. the mention of the deposit last named places this in a striking light. we have seen that the wealden beds, under the chalk, represent a mesozoic estuary, and in it we have the remains of the animals and plants of the land that then was. the great cretaceous subsidence intervened, and in the london clay we have an estuary of the eocene. but if we pass through the galleries of a museum where these formations are represented, though we know that both existed in the same locality under a warm climate, we see that they belong to two different worlds, the one to that of the dinosaurs, the ammonites, the cycads, and the minute marsupials of the mesozoic, the other to that of the pachyderms, the palms, and the nautili of the tertiary. the london clay is lower eocene; but in the beds of the isle of wight and neighbouring parts of the south of england, we have the middle and upper members of the series. they are not, however, so largely developed as in the paris basin, where, resting on the equivalent of the london clay, we have a thick marine limestone, the calcaire grossier, abounding in marine remains, and in some beds composed of shells of foraminifera. the sea in which this limestone was deposited, a portion no doubt of the great atlantic area of the period, became shallow, so that beds of sand succeeded those of limestone, and finally it was dried up into lake basins, in which gypsum, magnesian sediments, and siliceous limestone were deposited. these lakes or ponds must at some period have resembled the american "salt-licks," and were no doubt resorted to by animals from all the surrounding country in search of the saline mud and water which they afforded. hence in some marly beds intervening between the layers of gypsum, numerous footprints occur, exactly like those already noticed in the trias. had there been a nimrod in those days to watch with bow or boomerang by the muddy shore, he would have seen herds of heavy short-legged and three-hoofed monsters (palæotherium), with large heads and long snouts, probably scantily covered with sleek hair, and closely resembling the modern tapirs of south america and india, laboriously wading through the mud, and grunting with indolent delight as they rolled themselves in the cool saline slime. others more light and graceful, combining some features of the antelope with those of the tapir (anoplotherium) ran in herds over the drier ridges, or sometimes timidly approached the treacherous clay, tempted by the saline waters. other creatures representing the modern damans or conies--"feeble folk" which, with the aspect of hares, have the structure of pachyderms--were also present. creatures of these types constituted the great majority of the animals of the parisian eocene lakes; but there were also carnivorous animals allied to the hyæna, the wolf, and the opossum, which prowled along the shores by night to seize unwary wanderers, or to prey on the carcases of animals mired in the sloughs. wading birds equal in size to the ostrich also stalked through the shallows, and tortoises crawled over the mud. lyell mentions the discovery of some bones of one of these gigantic birds (gastornis) in a bed of the rolled chalk flints which form the base of the paris series, resting immediately on the chalk; one of the first inhabitants perhaps to people some island of chalk just emerged from the waters, and under which lay the bones of the mighty dinosaurs, and in which were embedded those of sea birds that had ranged, like the albatross and petrel, over the wide expanse of the cretaceous ocean. these waders, however, like the tortoises and crocodiles and small marsupial mammals, form a link of connection in type at least between the eocene and the cretaceous, for bones of wading birds have been found in the greensands indicating their existence before the close of the mesozoic. the researches of baron cuvier in the bones collected in the quarries of montmartre were regarded as an astonishing triumph of comparative anatomy; and familiar as we now are with similar and yet more difficult achievements, we can yet afford to regard with admiration the work of the great french naturalist as it is recorded in its collected form in his "recherches sur les ossemens fossiles," published in . his clear and philosophical views as to the plan perceptible in nature, his admirable powers of classification, his acute perception of the correlation of parts in animals, his nice discrimination of the resemblances and differences of fossil and recent structures, and of the uses of these,--all mark him as one of the greatest minds ever devoted to the study of natural science. it is obvious, that had his intellect been occupied by the evolutionist metaphysics which pass for natural science with too many in our day, he would have effected comparatively little; and instead of the magnificent museum in the "règne animal" and the "ossemens fossiles," we might have had wearisome speculations on the derivation of species. it is reason for profound thankfulness that it was not so; and also that so many great observers and thinkers of our day, like sedgwick, murchison, lyell, owen, dana, and agassiz, have been allowed to work out their researches almost to completion before the advent of those poisoned streams and mephitic vapours which threaten the intellectual obscuration of those who should be their successors. if we pass from the eocene to the miocene, still confining ourselves mainly to mammalian life, we find three remarkable points of difference--( ) whereas the eocene mammals are remarkable for adherence to one general type, viz., that group of pachyderms most regular and complete in its dentition, we now find a great number of more specialised and peculiar forms; ( ) we find in the latter period a far greater proportion of large carnivorous animals; ( ) we find much greater variety of mammals then either in the eocene or the modern, and a remarkable abundance of species of gigantic size. the miocene is thus apparently the culminating age of the mammalia, in so far as physical development is concerned; and this, as we shall find, accords with its remarkably genial climate and exuberant vegetation. in europe, the beds of this age present, for the first time, examples of the monkeys, represented by two generic types, both of them apparently related to the modern long-armed species, or gibbons. among carnivorous animals we have cat-like creatures, one of which is the terrible _machairodus_, distinguished from all modern animals of its group by the long sabre-shaped canines of its upper jaw, fitting it to pull down and destroy those large pachyderms which could have easily shaken off a lion or a tiger. here also we have the elephants, represented by several species now extinct; the mastodon, a great, coarsely-built, hog-like elephant, some species of which had tusks both in the upper and lower jaw; the rhinoceros, the hippopotamus, and the horse, all of extinct species. we have also giraffes, stags, and antelopes, the first ruminants known to us, and a great variety of smaller and less noteworthy creatures. here also, for the first time, we find the curious and exceptional group of edentates, represented by a large ant-eater. of all the animals of the european miocene, the most wonderful and unlike any modern beast, is the dinotherium, found in the miocene of epplesheim in germany; and described by kaup. some doubt rests on the form and affinities of the animal; but we may reasonably take it, as restored by its describer, and currently reproduced in popular books, to have been a quadruped of somewhat elephantine form. some years ago, however, a huge haunch bone, supposed to belong to this creature, was discovered in the south of france; and from this it was inferred that the dinothere may have been a marsupial or pouched animal, perhaps allied in form and habits to the kangaroos. the skull is three feet four inches in length; and when provided with its soft parts, including a snout or trunk in front, it must have been at least five or six feet long. such a head, if it belonged to a quadruped of ordinary proportions, must represent an animal as large in proportion to our elephant as an elephant to an ox. but its size is not its most remarkable feature. it has two large tusks firmly implanted in strong bony sockets; but they are attached to the end of the lower jaw and point downward at right angles to it, so that the lower jaw forms a sort of double-pointed pickaxe of great size and strength. this might have been used as a weapon; or, if the creature was aquatic, as a grappling iron to hold by the bank, or by floating timber; but more probably it was a grubbing-hoe for digging up roots or loosening the bases of trees which the animal might afterward pull down to devour them. however this may be, the creature laboured under the mechanical disadvantage of having to lift an immense weight in the process of mastication, and of being unable to bring its mouth to the ground, or to bite or grasp anything with the front of its jaws. to make up for this, it had muscles of enormous power on the sides of the head attached to great projecting processes; and it had a thick but flexible proboscis, to place in its mouth the food grubbed up by its tusks. taken altogether, the dinothere is perhaps the most remarkable of mammals, fossil or recent; and if the rest of its frame were as extraordinary as its skull, we have probably as yet but a faint conception of its peculiarities. we may apply to it, with added force, the admiring ejaculation of job, when he describes the strength of the hippopotamus, "he is the chief of the ways of god. he who made him, gave him his sword." [illustration: miocene mammals of the eastern continent. in the foreground _elephas_, _ganesa_, _hydracotherium_, _dinotherium_, _machairodus_, _mastodon longirostris_. in the middle distance, _apes_, two _anoplotheres_, _palæotherium_, _xiphodon_, and _sivatherium_. sequoias and fan palm in the background.] in asia, the siwalik hills afforded to falconer and cautley one of the most remarkable exhibitions of miocene animals in the world. these hills form a ridge subordinate to the himalayan chain; and rise to a height of , to , feet. in the miocene period, they were sandy and pebbly shores and banks lying at the foot of the then infant himalayas, which, with the table-lands to the north, probably formed a somewhat narrow east and west continental mass or large island. as a mere example of the marvellous fauna which inhabited this miocene land, it has afforded remains of seven species of elephants, mastodons, and allied animals; one of them, the _e. ganesa_, with tusks ten feet and a half long, and twenty-six inches in circumference at the base. besides these there are five species of rhinoceros, three of horse and allied animals, four or more of hippopotamus, and species of camel, giraffe, antelope, sheep, ox, and many other genera, as well as numerous large and formidable beasts of prey. there is also an ostrich; and, among other reptiles, a tortoise having a shell twelve feet in length, and this huge roof must have covered an animal eighteen feet long and seven feet high. among the more remarkable of the siwalik animals is the _sivatherium_, a gigantic four-horned antelope or deer, supposed to have been of elephantine size, and of great power and swiftness; and to have presented features connecting the ruminants and pachyderms. our restoration of this creature is to some extent conjectural; and a remarkably artistic, and probably more accurate, restoration of the animal has recently been published by dr. murie, in the geological magazine. we justly regard the mammalian fauna of modern india as one of the noblest in the world; but it is paltry in comparison with that of the much more limited miocene india; even if we suppose, contrary to all probability, that we know most of the animals of the latter. but if we consider the likelihood that we do not yet know a tenth of the miocene animals, the contrast becomes vastly greater. miocene america is scarcely behind the old world in the development of its land animals. from one locality in nebraska, leidy described in fifteen species of large quadrupeds; and the number has since been considerably increased. among these are species of rhinoceros, palæotherium, and machairodus; and one animal, the titanotherium, allied to the european anoplothere, is said to have attained a length of eighteen feet and a height of nine, its jaws alone being five feet long. in the illustration, i have grouped some of the characteristic mammalian forms of the miocene, as we can restore them from their scattered bones, more or less conjecturally; but could we have seen them march before us in all their majesty, like the edenic animals before adam, i feel persuaded that our impressions of this wonderful age would have far exceeded anything that we can derive either from words or illustrations. i insist on this the more that the miocene happens to be very slenderly represented in britain; and scarcely at all in north-eastern america; and hence has not impressed the imagination of the english race so strongly as its importance justifies. the next succeeding period, that of the pliocene, continues the conditions of the last, but with signs of decadence. many of the old gigantic pachyderms have disappeared; and in their stead some familiar modern genera were introduced. the pliocene was terminated by the cold or glacial period, in which a remarkable lowering of temperature occurred over all the northern hemisphere, accompanied, at least in a portion of the time, by a very general and great subsidence, which laid all the lower parts of our continents under water. this terminated much of the life of the pliocene, and replaced it with boreal and arctic forms, some of them, like the great hairy siberian mammoth and the woolly rhinoceros, fit successors of the gigantic miocene fauna. how it happened that such creatures were continued during the post-pliocene cold, we cannot understand till we have the tertiary vegetation before us. it must suffice now to say, that as the temperature was modified, and the land rose, and the modern period was inaugurated, these animals passed away, and those of the present time remained. perhaps the most remarkable fact connected with this change, is that stated by pictet, that all the modern european mammals are direct descendants of post-pliocene species; but that in the post-pliocene they were associated with many other species; and these, often of great dimensions, now extinct. in other words, the time from the pliocene to the modern, has been a time of diminution of species, while that from the eocene to the miocene was a time of rapid introduction of new species. thus the tertiary fauna culminated in the miocene. yet, strange though this may appear, man himself, the latest and noblest of all, would seem to have been a product of the later stages of the time of decadence. i propose, however, to return to the animals immediately preceding man and his contemporaries, after we have noticed the tertiary flora and the glacial period. chapter xi. the neozoic ages (_continued_). plant-life in the tertiary approaches very nearly to that of the modern world, in so far as its leading types are concerned; but in its distribution geographically it was wonderfully different from that with which we are at present familiar. for example, in the isle of sheppey, at the mouth of the themes, are beds of "london clay," fall of fossil nuts; and these, instead of being hazel nuts and acorns, belong to palms allied to species now found in the philippine islands and bengal, while with them are numerous cone-like fruits belonging to the proteaceæ (banksias, silver-trees, wagenbooms, etc.), a group of trees now confined to australia and south africa, but which in the northern hemisphere had already, as stated in a previous paper, made their appearance in the cretaceous, and were abundant in the eocene. the state of preservation of these fruits shows that they were not drifted far; and in some beds in hampshire, also of eocene age, the leaves of similar plants occur along with species of fig, cinnamon, and other forms equally australian or indian. in america, especially in the west, there are thick and widely-distributed beds of lignite or imperfect coal of the eocene period; but the plants found in the american eocene are more like those of the european miocene or the modern american flora, a fact to which we must revert immediately. in europe, while the eocene plants resemble those of australia, when we ascend into the miocene they resemble those of america, though still retaining some of the australian forms. in the leaf-beds of the isle of mull,--where beds of vegetable mould and leaves were covered up with the erupted matter of a volcano belonging to a great series of such eruptions which produced the basaltic cliffs of antrim and of staffa,--and at bovey, in devonshire, where miocene plants have accumulated in many thick beds of lignite, the prevailing plants are sequoias or red-woods, vines, figs, cinnamons, etc. in the sandstones at the base of the alps similar plants and also palms of american types occur. in the upper miocene beds of oeningen in the rhine valley, nearly five hundred species of plants have been found, and include such familiar forms as the maples, plane-trees, cypress, elm, and sweet-gum, more american, however, then european in their aspect. it thus appears that the miocene flora of europe resembles that of america at pre sent, while the eocene flora of europe resembles that of australia, and the eocene flora of america, as well as the modern, resembles the miocene of europe. in other words, the changes of the flora have been more rapid in europe then in america and probably slowest of all in australia. the eastern continent has thus taken the lead in rapidity of change in the tertiary period, and it has done so in animals as well as in plants. the following description of the flora of bovey is given, with slight alteration, in the words of dr. heer, in his memoir on that district. the woods that covered the slopes consisted mainly of a huge pine-tree (sequoia), whose figure resembled in all probability its highly-admired cousin, the giant wellingtonia of california. the leafy trees of most frequent occurrence were the cinnamon and an evergreen oak like those now seen in mexico. the evergreen figs, the custard apples, and allies of the cape jasmine, were rarer. the trees were festooned with vines, beside which the prickly rotang palm twined its snake-like form. in the shade of the forest throve numerous ferns, one species of which formed trees of imposing grandeur, and there were masses of under-wood belonging to various species of nyssa, like the tupelos and sour-gums of north america. this is a true picture, based on actual facts, of the vegetation of england in the miocene age. but all the other wonders of the miocene flora are thrown into the shade by the discoveries of plants of this age which have recently been made in greenland, a region now bound up in what we poetically call eternal ice, but which in the miocene was a fair and verdant land, rejoicing in a mild climate and rich vegetation. the beds containing these specimens occur in various places in north greenland; and the principal locality, atane-kerdluk, is in lat. n. and at an elevation of more then a thousand feet above the sea. the plants occur abundantly in sandstone and clay beds, and the manner in which delicate leaves and fruits are preserved shows that they have not been far water-borne, a conclusion which is confirmed by the occurrence of beds of lignite of considerable thickness, and which are evidently peaty accumulations containing trunks of trees. the collections made have enabled heer to catalogue species, all of them of forms proper to temperate, or even warm regions, and mostly american in character. as many as forty-six of the species already referred to as occurring at bovey tracey and oeningen occur also in the greenland beds. among the plants are many species of pines, some of them of large size; and the beeches, oaks, planes, poplars, maples, walnuts, limes, magnolias, and vines are apparently as well represented as in the warm temperate zone of america at the present day. this wonderful flora was not a merely local phenomenon, for similar plants are found in spitzbergen in lat. ° '. it is to be further observed, that while the general characters of these ancient arctic plants imply a large amount of summer heat and light, the evergreens equally imply a mild winter. further, though animal remains are not found with these plants, it is probable that so rich a supply of vegetable food was not unutilised, and that we shall some time find that there was an arctic fauna corresponding to the arctic flora. how such a climate could exist in greenland and spitzbergen is still a mystery. it has, however, been suggested that this effect might result from the concurrence of such astronomical conditions in connection with the eccentricity of the earth's orbit as would give the greatest amount of warmth in the northern hemisphere with such distribution of land and water as would give the least amount of cold northern land and the most favourable arrangement of the warm surface currents of the ocean.[ai] [ai] croll and lyell. before leaving these miocene plants, i must refer to a paragraph which dr. heer has thought it necessary to insert in his memoir on the greenland flora, and which curiously illustrates the feebleness of what with some men passes for science. he says: "in conclusion, i beg to offer a few remarks on the amount of certainty in identification which the determination of fossil plants is able to afford us. we know that the flowers, fruits, and seeds are more important as characteristics then the leaves. there are many genera of which the leaves are variable, and consequently would be likely to lead us astray if we trusted in them alone. however, many characters of the form and venation of leaves are well-known to be characteristic of certain genera, and can therefore afford us characters of great value for their recognition." in a similar apologetic style he proceeds through several sentences to plead the cause of his greenland leaves. that he should have to do so is strange, unless indeed the botany known to those for whom he writes is no more then that which a school-girl learns in her few lessons in dissecting a buttercup or daisy. it is easy for scientific triflers to exhibit collections of plants in which species of different genera and families are so similar in their leaves that a careless observer would mistake one for the other, or to get up composite leaves in part of one species and in part of another, and yet seeming the same, and in this way to underrate the labours of painstaking observers like heer. but it is nevertheless true that in any of these leaves, not only are there good characters by which they can be recognised, but that a single breathing pore, or a single hair, or a few cells, or a bit of epidermis not larger then a pin's head, should enable any one who understands his business to see as great differences as a merely superficial botanist would see between the flower of a ranunculus and that of a strawberry. heer himself, and the same applies to all other competent students of fossil plants, has almost invariably found his determinations from mere fragments of leaves confirmed when more characteristic parts were afterwards discovered. it is high time, in the interests of geology, that botanists should learn that constancy and correlation of parts are laws in the plant as well as in the animal; and this they can learn only by working more diligently with the microscope. i would, however, go further then this, and maintain that, in regard to some of the most important geological conclusions to be derived from fossils, even the leaves of plants are vastly more valuable then the hard parts of animals. for instance, the bones of elephants and rhinoceroses found in greenland would not prove a warm climate; because the creatures might have been protected from cold with hair like that of the musk-sheep, and they might have had facilities for annual migrations like the bisons. the occurrence of bones of reindeer in france does not prove that its climate was like that of lapland; but only that it was wooded, and that the animals could rove at will to the hills and to the coast. but, on the other hand, the remains of an evergreen oak in greenland constitute absolute proof of a warm and equable climate; and the occurrence of leaves of the dwarf birch in france constitutes a proof of a cool climate, worth more then that which can be derived from the bones of millions of reindeer and musk-sheep. still further, in all those greater and more difficult questions of geology which relate to the emergence and submergence of land areas, and to the geographical conditions of past geological periods, the evidence of plants, especially when rooted in place, is of far more value then that of animals, though it has yet been very little used. this digression prepares the way for the question: was the miocene period on the whole a better age of the world then that in which we live? in some respects it was. obviously there was in the northern hemisphere a vast surface of land under a mild and equable climate, and clothed with a rich and varied vegetation. had we lived in the miocene, we might have sat under our vine and fig-tree equally in greenland and spitzbergen and in those more southern climes to which this privilege is now restricted. we might have enjoyed a great variety of rich and nutritive fruits, and, if sufficiently muscular, and able to cope with the gigantic mammals of the period, we might have engaged in either the life of the hunter or that of the agriculturist under advantages which we do not now possess. on the whole, the miocene presents to us in these respects the perfection of the neozoic time, and its culmination in so far as the nobler forms of brute animals and of plants are concerned. had men existed in those days, however, they should have been, in order to suit the conditions surrounding them, a race of giants; and they would probably have felt the want of many of those more modern species belonging to the flora and fauna of europe and western asia on which man has so much depended for his civilization. some reasons have been adduced for the belief that in the miocene and eocene there were intervals of cold climate; but the evidence of this may be merely local and exceptional, and does not interfere with the broad characteristics of the age as sketched above. the warm climate and rich vegetation of the miocene extended far into the pliocene, with characters very similar to those already stated; but as the pliocene age went on, cold and frost settled down upon the northern hemisphere, and a remarkable change took place in its vegetable productions. for example, in the somewhat celebrated "forest bed" of cromer, in norfolk, which is regarded as newer pliocene, we have lost all the foreign and warm-climate plants of the miocene, and find the familiar scotch firs and other plants of the modern british flora. the animals, however, retain their former types; for two species of elephant, a hippopotamus, and a rhinoceros are found in connection with these plants. this is another evidence, in addition to those above referred to, that plants are better thermometers to indicate geological and climatal change then animals. this pliocene refrigeration appears to have gone on increasing into the next or post-pliocene age, and attained its maximum in the glacial period, when, as many geologists think, our continents were, even in the temperate latitudes, covered with a sheet of ice like that which now clothes greenland. then occurred a very general subsidence, in which they were submerged under the waters of a cold icy sea, tenanted by marine animals now belonging to boreal and arctic regions. after this last great plunge-bath they rose to constitute the dry land of man and his contemporaries. let us close this part of the subject with one striking illustration from heer's memoir on bovey tracey. at this place, above the great series of clays and lignites containing the miocene plants already described, is a thick covering of clay, gravel, and stones, evidently of much later date. this also contains some plants; but instead of the figs, and cinnamons, and evergreen oaks, they are the petty dwarf birch of scandinavia and the highland hills, and three willows, one of them the little arctic and alpine creeping willow. thus we have in the south of england a transition in the course of the pliocene period, from a climate much milder then that of modern england to one almost arctic in its character. our next topic for consideration is one of the most vexed questions among geologists, the glacial period which immediately preceded the advent of man. in treating of this it will be safest first to sketch the actual appearances which present themselves, and then to draw such pictures as we can of the conditions which they represent. the most recent and superficial covering of the earth's crust is usually composed of rock material more or less ground up and weathered. this may, with reference to its geological character and origin, be considered as of three kinds. it may be merely the rock weathered and decomposed to a certain extent _in situ_; or it may be alluvial matter carried or deposited by existing streams or tides, or by the rains; or, lastly, it may be material evidencing the operation of causes not now in action. this last constitutes what has been called drift or diluvial detritus, and is that with which we have now to do. such drift, then, is very widely distributed on our continents in the higher latitudes. in the northern hemisphere it extends from the arctic regions to about ° of north latitude in europe, and as low as ° in north america; and it occurs south of similar parallels in the southern hemisphere. farther towards the equator then the latitudes indicated, we do not find the proper drift deposits, but merely weathered rocks or alluvia, or old sea bottoms raised up. this limitation of the drift, at the very outset gives it the character of a deposit in some way connected with the polar cold. besides this, the general transport of stones and other material in the northern regions has been to the south; hence in the northern hemisphere this deposit may be called the _northern_ drift. if now we take a typical locality of this formation, such, for instance, as we may find in scotland, or scandinavia, or canada, we shall find it to consist of three members, as follows:-- . superficial sands or gravels. . stratified clays. . till or boulder clay. this arrangement may locally be more complicated, or it may be deficient in one of its members. the boulder clay may, for example, be underlaid by stratified sand or gravel, or even by peaty deposits; it may be intermixed with layers of clay or sand; the stratified clay or the boulder clay may be absent, or may be uncovered by any upper member. still we may take the typical series as above stated, and inquire as to its characters and teaching. the lower member, or boulder clay, is a very remarkable kind of deposit, consisting of a paste which may graduate from tough clay to loose sand, and which holds large angular and rounded stones or boulders confusedly intermixed; these stones may be either from the rocks found in the immediate vicinity of their present position, or at great distances. this mass is usually destitute of any lamination or subordinate stratification, whence it is often called _unstratified_ drift, and is of very variable thickness, often occurring in very thick beds in valleys, and being comparatively thin or absent on intervening hills. further, if we examine the stones contained in the boulder clay, we shall find that they are often scratched or striated and grooved; and when we remove the clay from the rock surfaces on which it rests, we find these in like manner striated, grooved and polished. these phenomena, viz., of polished and striated rocks and stones, are similar to those produced by those great sliding masses of ice, the glaciers of alpine regions, which in a small way and in narrow and elevated valleys, act on the rocks and stones in this manner, though they cannot form deposits precisely analogous to the boulder clay, owing to the wasting away of much of the finer material by the torrents, and the heaping of the coarser detritus in ridges and piles. further, we have in greenland a continental mass, with all its valleys thus filled with slowly-moving ice, and from this there drift off immense ice-islands, which continue at least the mud-and-stone-depositing process, and possibly also the grinding process, over the sea bottom. so far all geologists are agreed; but here they diverge into two schools. one of these, then of the glacier theorists, holds that the boulder clay is the product of land-ice; and this requires the supposition that at the time when it was deposited the whole of our continents north of ° or ° was in the condition of greenland at present. this is, however, a hypothesis so inconvenient, not to say improbable, that many hesitate to accept it, and prefer to believe that in the so-called glacial period the land was submerged, and that icebergs then as now drifted from the north in obedience to the arctic currents, and produced the effects observed. it would be tedious to go into all the arguments of the advocates of glaciers and icebergs, and i shall not attempt this, more especially as the only way to decide the question is to observe carefully the facts in every particular locality, and inquire as to the conclusions fairly deducible. with the view of aiding such a solution, however, i may state a few general principles applicable to the appearances observed. we may then suppose that boulder clay may be formed in three ways. ( ) it may be deposited on land, as what is called the bottom moraine of a land glacier. ( ) it may be deposited in the sea when such a glacier ends on the coast. ( ) it may be deposited by the melting or grounding on muddy bottoms of the iceberg masses floated off from the end of such a glacier. it is altogether likely, from the observations recently made in greenland, that in that country such a deposit is being formed in all these ways. in like manner, the ancient boulder clay may have been formed in one or more of these ways in any given locality where it occurs, though it may be difficult in many instances to indicate the precise mode. there are, however, certain criteria which may be applied to the determination of its origin, and i may state a few of these, which are the results of my own experience. ( ) where the boulder clay contains marine shells, or rounded stones which if exposed to the air would have been cracked to pieces, decomposed, or oxidized, it must have been formed under water. where the conditions are the reverse of these, it may have been formed on land. ( ) when the striations and transport of materials do not conform to the levels of the country, and take that direction, usually n.e. and s.w., which the arctic current would take if the country were submerged, the probability is that it was deposited in the sea. where, however, the striation and transport take the course of existing valleys, more especially in hilly regions, the contrary may be inferred. ( ) where most of the material, more especially the large stones, has been carried to great distances from its original site, especially over plains or up slopes, it has probably been sea-borne. where it is mostly local, local ice-action may be inferred. other criteria may be stated, but these are sufficient for our present purpose. their application in every special case i do not presume to make; but i am convinced that when applied to those regions in eastern america with which i am familiar, they necessitate the conclusion that in the period of extreme refrigeration, the greater part of the land was under water, and such hills and mountains as remained were little greenlands, covered with ice and sending down glaciers to the sea. in hilly and broken regions, therefore, and especially at considerable elevations, we find indications of _glacier_ action; on the great plains, on the contrary, the indications are those of _marine_ glaciation and transport. this last statement, i believe, applies to the mountains and plains of europe and asia as well as of america. this view requires not only the supposition of great refrigeration, but of a great subsidence of the land in the temperate latitudes, with large residual islands and hills in the arctic regions. that such subsidence actually took place is proved, not only by the frequent occurrence of marine shells in the boulder clay itself, but also by the occurrence of stratified marine clays filled with shells, often of deep-water species, immediately over that deposit. further, the shells, and also occasional land plants found in these beds, indicate a cold climate and much cold fresh water pouring into the sea from melting ice and snow. in canada these marine clays have been traced up to elevations of feet, and in great britain deposits of this kind occur on one of the mountains of wales at the height of feet above the level of the sea. nor is it to be supposed that this level marks the extreme height of the post-pliocene waters, for drift material not explicable by glaciers, and evidences of marine erosion, occur at still higher levels, and it is natural that on high and exposed points fewer remains of fossiliferous beds should be left then in plains and valleys. at the present day the coasts of britain and other parts of western europe enjoy an exceptionally warm temperature, owing to the warm currents of the atlantic being thrown on them, and the warm and moist atlantic air flowing over them, under the influence of the prevailing westerly winds. these advantages are not possessed by the eastern coast of north america, nor by some deep channels in the sea, along which the cold northern currents flow under the warmer water. hence these last-mentioned localities are inhabited by boreal shells much farther south then such species extend on the coasts and banks of great britain. in the glacial period this exceptional advantage was lost, and while the american seas, as judged by their marine animals, were somewhat colder then at present, the british seas were proportionally much more cooled down. no doubt, however, there were warmer and colder areas, determined by depth and prevailing currents, and as these changed their position in elevation and subsidence of the land, alternations and even mixtures of the inhabitants of cold and warm water resulted, which have often been very puzzling to geologists. i have taken the series of drift deposits seen in britain and in canada as typical, and the previous discussion has had reference to them. but it would be unfair not to inform the reader that this succession of deposits after all belongs to the margins of our continents rather then to their great central areas. this is the case at least in north america, where in the region of the great lakes the oldest glaciated surfaces are overlaid by thick beds of stratified clay, without marine fossils, and often without either stones or boulders, though these sometimes occur, especially toward the north. the clay, however, contains drifted fragments of coniferous trees. above this clay are sand and gravel, and the principal deposit of travelled stones and boulders rests on these. i cannot affirm that a similar succession occurs on the great inland plains of europe and asia: but i think it probable that to some extent it does. the explanation of this inland drift by the advocates of a great continental glacier is as follows: ( ) in the pliocene period the continents were higher then at present, and many deep valleys, since filled up, were cut in them. ( ) in the post-pliocene these elevated continents became covered with ice, by the movement of which the valleys were deepened and the surfaces striated. ( ) this ice-period was followed by a depression and submergence, in which the clays were deposited, filling up old channels, and much changing the levels of the land. lastly, as the land rose again from this submergence, sand and gravel were deposited, and boulders scattered over the surface by floating ice. the advocates of floating ice as distinguished from a continental glacier, merely dispense with the latter, and affirm that the striation under the clay, as well as that connected with the later boulders, is the effect of floating bergs. the occurrence of so much drift wood in the clay favours their view, as it is more likely that there would be islands clothed with trees in the sea, then that these should exist immediately after the country had been mantled in ice. the want of marine shells is a difficulty in either view, but may be accounted for by the rapid deposition of the clay and the slow spreading of marine animals over a submerged continent under unfavourable conditions of climate. in any case the reader will please observe that theorists must account for both the interior and marginal forms of these deposits. let us tabulate the facts and the modes of accounting for them. ------------------------------------+------------------------------------ facts observed. | theoretical views. -------------------+----------------+------------------------------------ inland plains. | marginal areas.|glacial theories.| floating ice | | | theories. ===================+================+==================================== terraces. | terraces and | emergence of modern land.[aj] | raised beaches.| -------------------+----------------+------------------------------------ travelled boulders |sand and gravel,| and glaciated |with sea shells | stones and rocks |and boulders. | shallow sea and floating ice. stratified sand | | and gravel. | | -------------------+----------------+------------------------------------ stratified clay |stratified clay | deep sea and floating ice. with drift wood, |with sea shells.+----------------+------------------- and a few stones. |boulder clay |submergence of |much floating ice and boulders. |with or without |the land. great |and local glaciers. striated rocks. |sea shells. |continental |submergence of |striated rocks. |mantle of ice. |pliocene land. -------------------+----------------+----------------+------------------- old channels, |old channels, |erosion by |erosion by indicating a higher|etc., indicating|continental |atmospheric level of the land. |previous dry |glacier. |agencies and |land. | |accumulation of | | |decomposed rock. -------------------+----------------+----------------+------------------- [aj] the phenomena of this period, with reference to rainfall, melting snows, and valley deposits, must be noticed in the next chapter. this table will suffice at least to reduce the great glacier controversy to its narrowest limits, when we have added the one further consideration that glaciers are the parents of icebergs, and that the question is not of one or the other exclusively, but of the relative predominance of the one or the other in certain given times and places. both theories admit a great post-pliocene subsidence. the abettors of glaciers can urge the elevation of the surface, the supposed powers of glaciers as eroding agents, and the transport of boulders. those whose theoretical views lean to floating ice, believe that they can equally account for these phenomena, and can urge in support of their theory the occurrence of drift wood in the inland clay and boulder clay, and of sea-shells in the marginal clay and boulder clay, and the atmospheric decomposition of rock in the pliocene period, as a source of the material of the clays, while to similar causes they can attribute the erosion of the deep valleys piled with the post-pliocene deposits. they can also maintain that the general direction of striation and drift implies the action of sea currents, while they appeal to local glaciers to account for special cases of glaciated rocks at the higher levels. how long our continental plateaus remained under the icy seas of the glacial period we do not know. relatively to human chronology, it was no doubt a long time; but short in comparison with those older subsidences in which the great palæozoic limestones were produced. at length, however, the change came. slowly and gradually, or by intermittent lifts, the land rose: and as it did so, shallow-water sands and gravels were deposited on the surface of the deep-sea clays, and the sides of the hills were cut into inland cliffs and terraces, marking the stages of recession of the waters. at length, when the process was complete, our present continents stood forth in their existing proportions ready for the occupancy of man. the picture which these changes present to the imagination is one of the most extraordinary in all geological history. we have been familiar with the idea of worlds drowned in water, and the primeval incandescent earth shows us the possibility of our globe being melted with fervent heat; but here we have a world apparently frozen out destroyed by cold, or doubly destroyed by ice and water. let us endeavour to realise this revolution, as it may have occurred in any of the temperate regions of the northern hemisphere, thickly peopled with the magnificent animals that had come down from the grand old miocene time. gradually the warm and equable temperature gives place to cold winters and chilly wet summers. the more tender animals die out, and the less hardy plants begin to be winter-killed, or to fail to perfect their fruits. as the forests are thus decimated, other and hardier species replace those which disappear. the animals which have had to confine themselves to sheltered spots, or which have perished through cold or want of food, are replaced by others migrating from the mountains, or from colder regions. some, perhaps, in the course of generations, become dwarfed in stature, and covered with more shaggy fur. permanent snow at length appears upon the hill-tops, and glaciers plough their way downward, devastating the forests, encroaching on the fertile plains, and at length reaching the heads of the bays and fiords. while snow and ice are thus encroaching from above, the land is subsiding, and the sea is advancing upon it, while great icebergs drifting on the coasts still further reduce the temperature. torrents and avalanches from the hills carry mud and gravel over the plains. peat bogs accumulate in the hollows. glaciers heap up confused masses of moraine, and the advancing sea piles up stones and shingle to be imbedded in mud on its further advance, while boreal marine animals invade the now submerged plains. at length the ice and water meet everywhere, or leave only a few green strips where hardy arctic plants still survive, and a few well-clad animals manage to protract their existence. perhaps even these are overwhelmed, and the curtain of the glacial winter falls over the fair scenery of the pliocene. in every locality thus invaded by an apparently perpetual winter, some species of laud animals must have perished. others may have migrated to more genial climes, others under depauperated and hardy varietal forms may have continued successfully to struggle for existence. the general result must have been greatly to diminish the nobler forms of life, and to encourage only those fitted for the most rigorous climates and least productive soils. could we have visited the world in this dreary period, and have witnessed the decadence and death of that brilliant and magnificent flora and fauna which we have traced upward from the eocene, we might well have despaired of the earth's destinies, and have fancied it the sport of some malignant demon; or have supposed that in the contest between the powers of destruction and those of renovation the former had finally gained the victory. we must observe, however, that the suffering in such a process is less then we might suppose. so long as animals could exist, they would continue to enjoy life. the conditions unfavourable to them would be equally or more so to their natural enemies. only the last survivors would meet with what might be regarded as a tragical end. as one description of animal became extinct, another was prepared to occupy its room. if elephants and rhinoceroses perished from the land, countless herds of walruses and seals took their places. if gay insects died and disappeared, shell-fishes and sea-stars were their successors. thus in nature there is life even in death, and constant enjoyment even when old systems are passing away. but could we have survived the glacial period, we should have seen a reason for its apparently wholesale destruction. out of that chaos came at length an eden; and just as the permian prepared the way for the mesozoic, so the glaciers and icebergs of the post-pliocene were the ploughshare of god preparing the earth for the time when, with a flora and fauna more beautiful and useful, if less magnificent then that of the tertiary, it became as the garden of the lord, fitted for the reception of his image and likeness, immortal and intelligent man. we need not, however, with one modern school of philosophy, regard man himself as but a descendant of miocene apes, scourged into reason and humanity by the struggle for existence in the glacial period. we may be content to consider him as a son of god, and to study in the succeeding chapters that renewal of the post-pliocene world which preceded and heralded his advent. in the meantime, our illustration,[ak] borrowed in part from the magnificent representation of the post-pliocene fauna of england, by the great restorer of extinct animals, mr. waterhouse hawkins, may serve to give some idea of the grand and massive forms of animal life which, even in the higher latitudes, survived the post-pliocene cold, and only decayed and disappeared under that amelioration of physical conditions which marks the introduction of the human period. [ak] page . chapter xii. close of the post-pliocene, and advent of man. _in_ closing these sketches it may seem unsatisfactory not to link the geological ages with the modern period in which we live; yet, perhaps, nothing is more complicated or encompassed with greater difficulties or uncertainties. the geologist, emerging from the study of the older monuments of the earth's history, and working with the methods of physical science, here meets face to face the archæologist and historian, who have been tracing back in the opposite direction, and with very different appliances, the stream of human history and tradition. in such circumstances conflicts may occur, or at least the two paths of inquiry may refuse to connect themselves without concessions unpleasant to the pursuers of one or both. further, it is just at this meeting-place that the dim candle of traditional lore is almost burnt out in the hand of the antiquary, and that the geologist finds his monumental evidence becoming more scanty and less distinct. we cannot hope as yet to dispel all the shadows that haunt this obscure domain, but can at least point out some of the paths which traverse it. in attempting this, we may first classify the time involved as follows: ( ) the earlier post-pliocene period of geology may be called the _glacial_ era. it is that of a cold climate, accompanied by glaciation and boulder deposits. ( ) the later _post-pliocene_ may be called the post-glacial era. it is that of re-elevation of the continents and restoration of a mild temperature. it connects itself with the pre-historic period of the archæologist, inasmuch as remains of man and his works are apparently included in the same deposits which hold the bones of post-glacial animals. ( ) the _modern_ era is that of secular human history. it may be stated with certainty that the pliocene period of geology affords no trace of human remains or implements; and the same may i think be affirmed of the period of glaciation and subsidence which constitutes the earlier post-pliocene. with the rise of the land out of the glacial sea indications of man are believed to appear, along with remains of several mammalian species now his contemporaries. archæology and geology thus meet somewhere in the pre-historic period of the former, and in the post-glacial of the latter. wherever, therefore, human history extends farthest back, and geological formations of the most modern periods exist and have been explored, we may expect best to define their junctions. unfortunately it happens that our information on these points is still very incomplete and locally limited. in many extensive regions, like america and australia, while the geological record is somewhat complete, the historic record extends back at most a few centuries, and the pre-historic monuments are of uncertain date. in other countries, as in western asia and egypt, where the historic record extends very far back, the geology is less perfectly known. at the present moment, therefore, the main battle-field of these controversies is in western europe, where, though history scarce extends farther back then the time of the roman republic, the geologic record is very complete, and has been explored with some thoroughness. it is obvious, however, that we thus have to face the question at a point where the pre-historic gap is necessarily very wide. taking england as an example, all before the roman invasion is pre-historic, and with regard to this pre-historic period the evidence that we can obtain is chiefly of a geological character. the pre-historic men are essentially fossils. we know of them merely what can be learned from their bones and implements embedded in the soil or in the earth of the caverns in which some of them sheltered themselves. for the origin and date of these deposits the antiquary must go to the geologist, and he imitates the geologist in arranging his human fossils under such names as the "paleolithic," or period of rude stone implements; the "neolithic" or period of polished stone implements; the bronze period, and the iron period; though inasmuch as higher and lower states of the arts seem always to have coexisted, and the time involved is comparatively short, these periods are of far less value then those of geology. in britain the age of iron is in the main historic. that of bronze goes back to the times of early phoenician trade with the south of england. that of stone, while locally extending far into the succeeding ages, reaches back into an unknown antiquity, and is, as we shall see in the sequel, probably divided into two by a great physical change, though not in the abrupt and arbitrary way sometimes assumed by those who base their classification solely on the rude or polished character of stone implements. we must not forget, however, that in western asia the ages of bronze and iron may have begun two thousand years at least earlier then in britain, and that in some parts of america the palaeolithic age of chipped stone implements still continues. we must also bear in mind that when the archæologist appeals to the geologist for aid, he thereby leaves that kind of investigation in which dates are settled by years, for that in which they are marked merely by successive physical and organic changes. turning, then, to our familiar geological methods, and confining ourselves mainly to the northern hemisphere and to western europe, two pictures present themselves to us: (!) the physical changes preceding the advent of man; ( ) the decadence of the land animals of the post-pliocene age, and the appearance of those of the modern. in the last chapter i had to introduce the reader to a great and terrible revolution, whereby the old pliocene continents, with all their wealth of animals and plants, became sealed up in a mantle of greenland ice, or, slowly sinking beneath the level of the sea, were transformed into an ocean-bottom over which icebergs bore their freight of clay and boulders. we also saw that as the post-pliocene age advanced, the latter condition prevailed, until the waters stood more then a thousand feet deep over the plains of europe. in this great glacial submergence, which closed the earlier post-pliocene period, and over vast areas of the northern hemisphere, terminated the existence of many of the noblest forms of life, it is believed that man had no share. we have, at least as yet, no record of his presence. out of these waters the land again rose slowly and intermittently, so that the receding waves worked even out of hard rocks ranges of coast cliff which the further elevation converted into inland terraces, and that the clay and stones deposited by the glacial waters were in many places worked over and rearranged by the tides and waves of the shallowing sea before they were permanently raised up to undergo the action of the rains and streams, while long banks of sand and gravel were stretched across plains and the mouths of valleys, constituting "kames," or "eskers," only to be distinguished from moraines of glaciers by the stratified arrangement of their materials. further, as the land rose, its surface was greatly and rapidly modified by rains and streams. there is the amplest evidence, both in europe and america, that at this time the erosion by these means was enormous in comparison with anything we now experience. the rainfall must have been excessive, the volume of water in the streams very great; and the facilities for cutting channels in the old pliocene valleys, filled to the brim with mud and boulder-clay, were unprecedented. while the area of the land was still limited, much of it would be high and broken, and it would have all the dampness of an insular climate. as it rose in height, plains which had, while under the sea, been loaded with the _débris_ swept from the land, would be raised up to experience river erosion. it was the spring-time of the glacial era, a spring eminent for its melting snows, its rains, and its river floods.[al] to an observer living at this time it would have seemed as if the slow process of moulding the continents was being pushed forward with unexampled rapidity. the valleys were ploughed out and cleansed, the plains levelled and overspread with beds of alluvium, giving new features of beauty and utility to the land, and preparing the way for the life of the modern period, as if to make up for the time which had been lost in the dreary glacial age. it will readily be understood how puzzling these deposits have been to geologists, especially to those who fail to present to their minds the true conditions of the period; and how difficult it is to separate the river alluvia of this age from the deposits in the seas and estuaries, and these again from the older glacial beds. further, in not a few instances the animals of a cold climate must have lived in close proximity to those which belonged to ameliorated conditions, and the fossils of the older post-pliocene must often, in the process of sorting by water, have been mixed with those of the newer. [al] mr. tylor has well designated this period as the pluvial age. _journal of the geological society_, . many years ago the brilliant and penetrating intellect of edward forbes was directed to the question of the maximum extent of the later post-pliocene or post-glacial land; and his investigations into the distribution of the european flora, in connection with the phenomena of submerged terrestrial surfaces, led to the belief that the land had risen until it was both higher and more extensive then at present. at the time of greatest elevation, england was joined to the continent of europe by a level plain, and a similar plain connected ireland with its sister islands. over these plains the plants constituting the "germanic" flora spread themselves into the area of the british islands, and herds of mammoth, rhinoceros, and irish elk wandered and extended their range from east to west. the deductions of forbes have been confirmed and extended by others; and it can scarcely be doubted that in the post-glacial era, the land regained fully the extent which it had possessed in the time of the pliocene. in these circumstances the loftier hills might still reach the limits of perpetual snow, but their glaciers would no longer descend to the sea. what are now the beds of shallow seas would be vast wooded plains, drained by magnificent rivers, whose main courses are now submerged, and only their branches remain as separate and distinct streams, the cold but equable climate of the post-pliocene would now be exchanged for warm summers, alternating with sharp winters, whose severity would be mitigated by the dense forest covering, which would also contribute to the due supply of moisture, preventing the surface from being burnt into arid plains. it seems not improbable that it was when the continents had attained to their greatest extension and when animal and vegetable life had again over-spread the new land to its utmost limits, that man was introduced on the eastern continent, and with him several mammalian species, not known in the pliocene period, and some of which, as the sheep, the goat, the ox, and the dog, have ever since been his companions and humble allies. these, at least in the west of europe, were the "palaeolithic" men, the makers of the oldest flint implements; and armed with these, they had to assert the mastery of man over broader lands then we now possess, and over many species of great animals now extinct. in thus writing, i assume the accuracy of the inferences from the occurrence of worked stones with the bones of post-glacial animals, which must have lived during the condition of our continents above referred to. if these inferences are well founded, not only did man exist at this time, but man not even varietally distinct from modern european races. but if man really appeared in europe in the post-glacial era, he was destined to be exposed to one great natural vicissitude before his permanent establishment in the world. the land had reached its maximum elevation, but its foundations, "standing in the water and out of the water," were not yet securely settled, and it had to take one more plunge-bath before attaining its modern fixity. this seems to have been a comparatively rapid subsidence and re-elevation, leaving but slender traces of its occurrence, but changing to some extent the levels of the continents, and failing to restore them fully to their former elevation, so that large areas of the lower grounds still remained under the sea. if, as the greater number of geologists now believe, man was then on the earth, it is not impossible that this constituted the deluge recorded in that remarkable "log book" of noah preserved to us in genesis, and of which the memory remains in the traditions of most ancient nations. this is at least the geological deluge which separates the post-glacial period from the modern, and the earlier from the later pre-historic period of the archæologists.[am] [am] i have long thought that the narrative in gen. vii. and viii. can be understood only on the supposition that it is a contemporary journal or log of an eye-witness incorporated by the author of genesis in his work. the dates of the rising and fall of the water, the note of soundings over the hill-tops when the maximum was attained, and many other details, as well as the whole tone of the narrative, seem to require this supposition, which also removes all the difficulties of interpretation which have been so much felt. very important questions of time are involved in this idea of post-glacial man, and much will depend, in the solution of these, on the views which we adopt as to the rate of subsidence and elevation of the land. if, with the majority of british geologists, we hold that it is to be measured by those slow movements now in progress, the time required will be long. if, with most continental and some american geologists, we believe in paroxysmal movements of elevation and depression, it may be much reduced. we have seen in the progress of our inquiries that the movements of the continents seem to have occurred with accelerated rapidity in the more modern periods. we have also seen that these movements might depend on the slow contraction of the earth's crust due to cooling, but that the effects of this contraction might manifest themselves only at intervals. we have further seen that the gradual retardation of the rotation of the earth furnishes a cause capable of producing elevation and subsidence of the land, and that this also might be manifested at longer or shorter intervals, according to the strength and resisting power of the crust. under the influence of this retardation, so long as the crust of the earth did not give way, the waters would be driven toward the poles, and the northern land would be submerged; but so soon as the tension became so great as to rupture the solid shell, the equatorial regions would collapse, and the northern land would again be raised. the subsidence would be gradual, the elevation paroxysmal, and perhaps intermittent. let us suppose that this was what occurred in the glacial period, and that the land had attained to its maximum elevation. this might not prove to be permanent; the new balance of the crust might be liable to local or general disturbance in a minor degree, leading to subsidence and partial re-elevation, following the great post-glacial elevation. there is, therefore, nothing unreasonable in that view which makes the subsidence and re-elevation at the close of the post-glacial period somewhat abrupt, at least when compared with some more ancient movements. but what is the evidence of the deposits formed at this period? here we meet with results most diverse and contradictory, but i think there can be little doubt that on this kind of evidence the time required for the post-glacial period has been greatly exaggerated, especially by those geologists who refuse to receive such views as to subsidence and elevation as those above stated. the calculations of long time based on the gravels of the somme, on the cone of the tinière, on the peat bogs of france and denmark, on certain cavern deposits, have all been shown to be more or less at fault; and possibly none of these reach further back then the six or seven thousand years which, according to dr. andrews, have elapsed since the close of the boulder-clay deposits in america.[an] i am aware that such a statement will be regarded with surprise by many in england, where even the popular literature has been penetrated with the idea of a duration of the human period immensely long in comparison with what used to be the popular belief; but i feel convinced that the scientific pendulum must swing backward in this direction nearer to its old position. let us look at a few of the facts. much use has been made of the "cone" or delta of the tinière on the eastern side of the lake of geneva, as an illustration of the duration of the modern period. this little stream has deposited at its mouth a mass of _débris_ carried down from the hills. this being cut through by a railway, is found to contain roman remains to a depth of four feet, bronze implements to a depth of ten feet, stone implements at a depth of nineteen feet. the deposit ceased about three hundred years ago, and calculating to years for the roman period, we should have to , years as the age of the cone. but before the formation of the present cone, another had been formed twelve times as large. thus for the two cones together, a duration of more then , years is claimed. it appears, however, that this calculation has been made irrespective of two essential elements in the question. no allowance has been made for the fact that the inner layers of a cone are necessarily smaller then the outer; nor for the further fact that the older cone belongs to a distinct time (the pluvial age already referred to), when the rainfall was much larger, and the transporting power of the torrent great in proportion. making allowance for these conditions, the age of the newer cone, that holding human remains, falls between and years. the peat bed of abbeville, in the north of france, has grown at the rate of one and a half to two inches in a century. being twenty-six feet in thickness, the time occupied in its growth must have amounted to , years; and yet it is probably newer then some of the gravels on the same river containing flint implements. but the composition of the abbeville peat shows that it's a forest peat, and the erect stems preserved in it prove that in the first instance it must have grown at the rate of about three feet in a century, and after the destruction of the forest its rate of increase down to the present time diminished rapidly almost to nothing. its age is thus reduced to perhaps less then years. in i had an opportunity to examine the now celebrated gravels of st. acheul, on the somme, by some supposed to go back to a very ancient period. with the papers of prestwich and other able observers in my hand, i could conclude merely that the undisturbed gravels were older then the roman period, but how much older only detailed topographical surveys could prove; and that taking into account the probabilities of a different level of the land, a wooded condition of the country, a greater rainfall, and a glacial filling of the somme valley with clay and stones subsequently cut out by running water the gravels could scarcely be older then the abbeville peat. to have published such views in england would have been simply to have delivered myself into the hands of the philistines. i therefore contented myself with recording my opinion in canada. tylor[ao] and andrews[ap] have, however, i think, subsequently shown that my impressions were correct. in like manner, i fail to perceive, and i think all american geologists acquainted with the pre-historic monuments of the western continent must agree with me, any evidence of great antiquity in the caves of belgium and england, the kitchen-middens of denmark, the rock-shelters of france, the lake habitations of switzerland. at the same time, i would disclaim all attempt to resolve their dates into precise terms of years. i may merely add, that the elaborate and careful observations of dr. andrews on the raised beaches of lake michigan, observations of a much more precise character then any which, in so far as i know, have been made of such deposits in europe, enable him to calculate the time which has elapsed since north america rose out of the waters of the glacial period as between and years. this fixes at least the possible duration of the human period in north america, though i believe there are other lines of evidence which, would reduce the residence of man in america to a much shorter time. longer periods have, it is true, been deduced from the delta of the mississippi and the gorge of niagara; but the deposits of the former have been found by hilgard to be in great part marine, and the excavation of the latter began at a period probably long anterior to the advent of man. [an] "transactions, chicago academy," . [ao] "journal of geological society," vol. xxv. [ap] "silliman's journal," . but another question remains. from the similarities existing in the animals and plants of regions in the southern hemisphere now widely separated by the ocean, it has been inferred that post-pliocene land of great extent existed there; and that on this land men may have lived before the continents of the northern hemisphere were ready for them. it has even been supposed that, inasmuch as the flora and fauna of australia have an aspect like that of the eocene tertiary, and very low forms of man exist in that part of the world, these low races are the oldest of all, and may date from tertiary times. positive evidence of this, however, there is none. these races have no monuments; nor, so far as known, have they left their remains in post-pliocene deposits. it depends on the assumptions that the ruder races of men are the oldest; and that man has no greater migratory powers then other animals. the first is probably false, as being contrary to history; and also to the testimony of palaeontology with reference to the laws of creation. the second is certainly false; for we know that man has managed to associate himself with every existing fauna and flora, even in modern times; and that the most modern races have pitched their tents amid tree-ferns and proteaceæ, and have hunted kangaroos and emus. further, when we consider that the productions of the southern hemisphere are not only more antique then those of the northern, but, on the whole, less suited for the comfortable subsistence of man and the animals most useful to him; and that the post-pliocene animals of the southern hemisphere were of similar types with their modern successors, we are the less inclined to believe that these regions would be selected as the cradle of the human race. condensed tabular view of the ages and periods of the neozoic. key to symbols ### recent species of aquatic invertebrates. teleostian fishes and squaloid sharks prevail. --- ages of angiosperms and plants. === "and god said--let the land bring forth herbivorous beasts and carnivorous beasts, after their kinds; and it was so." +++ "and god created man in his own image." time. ages. periods. animals and plants. neozoic or cainozoic. {newer. still future (?) age of + modern {middle. historic. man + {older. pre-historic. + + {n. post-glacial gravels and cave # + { deposits. saxicava sand and # + post- { terraces (america). # + pliocene {m. marine clays. leda clays. erie # - + { clay (america). # - + {o. glacial drift. boulder clay # - + { (america). # - + # - + {n. norwich crag; sicilian and # - { val d'arno beds. # - pliocene {m. ____________ sumter group (america). # - {o. red and coralline crag; sub-appenine # - = { beds. # - = # - = {n. faluns of loraine; upper molasse; # - = { siwalik beds; oeningen plant beds. # - = { york-town beds (america). # - = miocene {m. ____________ # - = {o. upper paris beds; hempstead and bovey # - = { beds; lower molasse. nebraska beds # - = { (west america). # mammals. - = # - = {n. gypseous series, paris. vicksburg # - = { group (america). # = eocene {m. calcaire grossier, bagshot and alum # = { bay beds. jackson group (america). = {o. argile plastique; london clay. = { claiborne group (america). = chapter xiii. close of the post-pliocene, and advent of man. (_continued._) turning from these difficult questions of time, we may now look at the assemblage of land-animals presented by the post-glacial period. here, for the first time in the great series of continental elevations and depressions, we find the newly-emerging land peopled with familiar forms. nearly all the modern european animals have left their bones in the clays, gravels, and cavern deposits which belong to this period; but with them are others either not now found within the limits of temperate europe, or altogether extinct. thus the remarkable fact comes out, that the uprising land was peopled at first with a more abundant fauna then that which it now sustains, and that many species, and among these some of the largest and most powerful, have been weeded out, either before the advent of man or in the changes which immediately succeeded that event. that in the post-glacial period so many noble animal species should have been overthrown in the struggle for existence, without leaving any successors, at least in europe, is one of the most remarkable phenomena in the history of life on our planet. according to. pictet,[aq] the post-glacial beds of europe afford ninety-eight species of mammals, of which fifty-seven still live there, the remainder being either locally or wholly extinct. according to mr. boyd dawkins,[ar] in great britain about twelve pliocene species survived the glacial period, and reappeared in the british islands in the post-glacial. to these were added forty-one species making in all fifty-three, whose remains are found in the gravels and caves of the latter period. of these, in the modern period twenty-eight, or rather more then one-half, survive, fourteen are wholly extinct, and eleven are locally extinct. [aq] palæontologie. [ar] "journal of geological society," and palæontographical society's publications. [illustration: britain in the post-pliocene age. musk-sheep, hippopotamus, machairodus, mammoth, wooly rhinoceros, long-fronted ox, and irish stag. the animals are taken from mr. waterhouse hawkins's picture, "struggles of life among british animals of the antediluvian times." london: . the landscape is that of the later part of the cold post-pliocene period.] among the extinct beasts, were some of very remarkable character. there were two or more species of elephant, which seem in this age to have overspread, in vast herds, all the plains of northern europe and asia; and one of which we know, from the perfect specimen found embedded in the frozen soil of siberia, lived till a very modern period; and was clothed with long hair and fur, fitting it for a cold climate. there were also three or four species of rhinoceros, one of which at least (the _r. tichorhinus_) was clad with wool like the great siberian mammoth. with these was a huge hippopotamus (_h. major_), whose head-quarters would, however, seem to have been farther south then england, or which perhaps inhabited chiefly the swamps along the large rivers running through areas now under the sea. the occurrence of such an animal shows an abundant vegetation, and a climate so mild, that the rivers were not covered with heavy ice in winter; for the supposition that this old hippopotamus was a migratory animal seems very unlikely. another animal of this time, was the magnificent deer, known as the irish elk; and which perhaps had its principal abode on the great plain which is now the irish sea. the terrible machairodus, or cymetar-toothed tiger, was continued from the pliocene; and in addition to species of bear still living, there was a species of gigantic size, probably now extinct, the cave bear. evidences are accumulating, to show that all or nearly all these survived until the human period. if we turn now to those animals which are only locally extinct, we meet with some strange, and at first sight puzzling anomalies. some of these are creatures now limited to climates much colder then that of britain. others now belong to warmer climates. conspicuous among the former are the musk-sheep, the elk, the reindeer, the glutton, and the lemming. among the latter, we see the panther, the lion, and the cape hyena. that animals now so widely separated as the musk-sheep of arctic america and the hyena of south africa, could ever have inhabited the same forests, seems a dream of the wildest fancy. yet it is not difficult to find a probable solution of the mystery. in north america, at the present day, the puma, or american lion, comes up to the same latitudes with the caribou, or reindeer, and moose; and in asia, the tiger extends its migrations into the abodes of boreal animals in the plains of siberia. even in europe, within the historic period, the reindeer inhabited the forests of germany; and the lion extended its range nearly as far northward. the explanation lies in the co-existence of a densely wooded country with a temperate climate; the forests affording to southern animals shelter from the cold or winter; and equally to the northern animals protection from the heat of summer. hence our wonder at this association of animals of diverse habitudes as to climate, is merely a prejudice arising from the present exceptional condition of europe. still it is possible that changes unfavourable to some of these animals, were in progress before the arrival of man, with his clearings and forest fires and other disturbing agencies. even in america, the megalonyx, or gigantic sloth, the mammoth, the mastodon, the fossil horse, and many other creatures, disappeared before the modern period; and on both continents the great post-glacial subsidence or deluge may have swept away some of the species. such a supposition seems necessary to account for the phenomena of the gravel and cave deposits of england, and cope has recently suggested it in explanation of similar storehouses of fossil animals in america.[as] [as] proceedings of the american philosophical society, april . among the many pictures which this fertile subject calls up, perhaps none is more curious then that presented by the post-glacial cavern deposits. we may close our survey of this period with the exploration of one of these strange repositories; and may select kent's hole at torquay, so carefully excavated and illumined with the magnesium light of scientific inquiry by mr. pengelly and a committee of the british association. the somewhat extensive and ramifying cavern of kent's hole is an irregular excavation, evidently due partly to fissures in limestone rock, and partly to the erosive action of water enlarging such fissures into chambers and galleries. at what time it was originally cut we do not know, but it must have existed as a cavern at the close of the pliocene or beginning of the post-pliocene period, since which time it has been receiving a series of deposits which have quite filled up some of its smaller branches. first and lowest, according to mr. pengelly, is a "breccia" or mass of broken and rounded stones, with hardened red clay filling the interstices. most of the stones are of the rock which forms the roof and walls of the cave, but many, especially the rounded ones, are from more distant parts of the surrounding country. in this mass, the depth of which is unknown, are numerous bones, all of one kind of animal, the cave bear, a creature which seems to have lived in western europe from the close of the pliocene down to the modern period. it must have been one of the earliest and most permanent tenants of kent's hole at a time when its lower chambers were still filled with water. next above the breccia is a floor of "stalagmite" or stony carbonate of lime, deposited from the drippings of the roof, and in some places three feet thick. this also contains bones of the cave bear, deposited when there was less access of water to the cavern. mr. pengelly infers the existence of man at this time from a single flint flake and a single flint chip found in these beds; but mere flakes and chips of flint are too often natural to warrant such a conclusion. after the old stalagmite floor above mentioned was formed, the cave again received deposits of muddy water and stones; but now a change occurs in the remains embedded. this stony clay, or "cave earth" has yielded an immense quantity of teeth and bones, including those of the elephant, rhinoceros, horse, hyena, cave bear, reindeer, and irish elk. with these were found weapons of chipped flint, and harpoons, needles, and bodkins of bone, precisely similar to those of the north american indians and other rude races. the "cave earth" is four feet or more in thickness, it is not stratified, and contains many fallen fragments of rock, rounded stones, and broken pieces of stalagmite. it also has patches of the excrement of hyenas, which the explorers suppose to indicate the temporary residence of these animals; and in one spot, near the top, is a limited layer of burnt wood, with remains which indicate the cooking and eating of repasts of animal food by man. it is clear that when this bed was formed the cavern was liable to be inundated with muddy water, carrying stones and other heavy objects, and breaking up in places the old stalagmite floor. one of the most puzzling features, especially to those who take an exclusively uniformitarian view, is, that the entrance of water-borne mud and stones implies a level of the bottom of the water in the neighbouring valleys of about feet above its present height. the cave earth is covered by a second crust of stalagmite, less dense and thick then that below, and containing only a few bones, which are of the same general character with those below, but include a fragment of a human jaw with teeth. evidently, when this stalagmite was formed, the influx of water-borne materials had ceased, or nearly so; but whether the animals previously occupying the country still continued in it, or only accidental bones, etc., were introduced into the cave or lifted from the bed below, does not appear. the next bed marks a new change. it is a layer of black mould from three to ten inches thick. its microscopic structure does not seem to have been examined; but it is probably a forest soil, introduced by growth, by water, by wind, and by ingress of animals, at a time when the cave was nearly in its present state, and the surrounding country densely wooded. this bed contains bones of animals, all of them modern, and works of art ranging from the old british times before the roman invasion up to the porter-bottles and dropped halfpence of modern visitors. lastly, in and upon the black mould are many fallen blocks from the roof of the cave. there can be no doubt that this cave and the neighbouring one of brixham have done very much to impress the minds of british geologists with ideas of the great antiquity of man, and they have, more then any other post-glacial monuments, shown the persistence of some animals now extinct up to the human age. of precise data for determining time, they have, however, given nothing. the only measures which seed to have been applied, namely, the rate of growth of stalagmite and the rate of erosion of the neighbouring valleys, are, from the very sequence of the deposits, obviously worthless; and the only apparently available constant measure, namely, the fall of blocks from the roof, seems not yet to have been applied. we are therefore quite uncertain as to the number of centuries involved in the filling of this cave, and must remain so until a surer system of calculation is adopted. we may, however, attempt to sketch the series of events which it indicates. the animals found in kent's hole are all "post-glacial." they therefore inhabited the country after it rose from the great glacial submergence. perhaps the first colonists of the coasts of devonshire in this period were the cave bears, migrating on floating ice, and subsisting, like the arctic bear, and the black bears of anticosti, on fish, and on the garbage cast up by the sea. they found kent's hole a sea-side cavern, with perhaps some of its galleries still full of water, and filling with, breccia, with which the bones of dead bears became mixed. as the land rose, these creatures for the most part betook themselves to lower levels, and in process of time the cavern stood upon a hill-side, perhaps several hundreds of feet above the sea; and the mountain torrents, their beds not yet emptied of glacial detritus, washed into it stones and mud and carcases of animals of many species which had now swarmed across the plains elevated out of the sea, and multiplied in the land. this was the time of the cave earth; and before its deposit was completed, though how long before, a confused and often-disturbed bed of this kind cannot tell, man himself seems to have been added to the inhabitants of the british land. in pursuit of game he sometimes ascended the valleys beyond the cavern, or even penetrated into its outer chambers; or perhaps there were even in those days rude and savage hill-men, inhabiting the forests and warring with the more cultivated denizens of plains below, which are now deep under the waters. their weapons, lost in hunting, or buried in the flesh of wounded animals which crept to the streams to assuage their thirst, are those found in the cave earth. the absence of human bones may merely show that the mighty hunters of those days were too hardy, athletic, and intelligent, often to perish from accidental causes, and that they did not use this cavern for a place of burial. but the land again subsided. the valley of that now nameless river, of which the rhine the themes, and the severn may have alike been tributaries, disappeared under the sea; and some tribe, driven from the lower lands, took refuge in this cave, now again near the encroaching waves, and left there the remains of their last repasts ere they were driven farther inland or engulfed in the waters. for a time the cavern may have been wholly submerged, and the charcoal of the extinguished fires became covered with its thin coating of clay. but ere long it re-emerged to form part of an island, long barren and desolate; and the valleys having been cut deeper by the receding waters, it no longer received muddy deposits, and the crust formed by drippings from its roof contained only bones and pebbles washed by rains or occasional land floods from its own clay deposits. finally, the modern forests overspread the land, and were tenanted by the modern animals. man returned to use the cavern again as a place of refuge or habitation, and to leave there the relics contained in the black earth. this seems at present the only intelligible history of this curious cave and others resembling it; though, when we consider the imperfection of the results obtained even by a large amount of labour, and the difficult and confused character of the deposits in this and similar caves, too much value should not be attached to such histories, which may at any time be contradicted or modified by new facts or different explanations of those already known. the time involved depends very much, as already stated, on the question whether we regard the post-glacial subsidence and re-elevation as somewhat sudden, or as occupying long ages at the slow rate at which some parts of our continents are now rising or sinking.[at] [at] another element in this is also the question raised by dawkins, geikie, and others as to subdivisions of the post-glacial period and intermissions of the glacial cold. after careful consideration of these views, however, i cannot consider them as of much importance. such are the glimpses, obscure though stimulating to the imagination, which geology can give of the circumstances attending the appearance of man in western europe. how far we are from being able to account for his origin, or to give its circumstances and relative dates for the whole world, the reader will readily understand. still it is something to know that there is an intelligible meeting-place of the later geological ages and the age of man, and that it is one inviting to many and hopeful researches. it is curious also to find that the few monuments disinterred by geology, the antediluvian record of holy scripture, and the golden age of heathen tradition, seem alike to point to similar physical conditions, and to that simple state of the arts of life in which "gold and wampum and flint stones"[au] constituted the chief material treasures of the earliest tribes of men. they also point to the immeasurable elevation, then as now, of man over his brute rivals for the dominion of the earth. to the naturalist this subject opens up most inviting yet most difficult paths of research, to be entered on with caution and reverence, rather then in the bold and dashing spirit of many modern attempts. the christian, on his part, may feel satisfied that the scattered monumental relics of the caves and gravels will tell no story very different from that which he has long believed on other evidence, nor anything inconsistent with those views of man's heavenly origin and destiny which have been the most precious inheritance of the greatest and best minds of every age, from that early pre-historic period when men, "palaeolithic" men, no doubt, began to "invoke the name of jehovah," the coming saviour, down to those times when life and immortality are brought to light, for all who will see, by the saviour already come. [au] so i read the "gold, bedolah, and shoham" of the description of eden in genesis ii.--the oldest literary record of the stone age. in completing this series of pictures, i wish emphatically to insist on the imperfection of the sketches which i have been able to present, and which are less, in comparison with the grand march of the creative work, even as now imperfectly known to science, then the roughest pencilling of a child when compared with a finished picture. if they have any popular value, it will be in presenting such a broad general view of a great subject as may induce further study to fill up the details. if they have any scientific value, it will be in removing the minds of british students for a little from the too exclusive study of their own limited marginal area, which has been to them too much the "celestial empire" around which all other countries must be arranged, and in divesting the subject of the special colouring given to it by certain prominent cliques and parties. geology as a science is at present in a peculiar and somewhat exceptional state. under the influence of a few men of commanding genius belonging to the generation now passing away, it has made so gigantic conquests that its armies have broken up into bands of specialists, little better then scientific banditti, liable to be beaten in detail, and prone to commit outrages on common sense and good taste, which bring their otherwise good cause into disrepute. the leaders of these bands are, many of them, good soldiers, but few of them fitted to be general officers, and none of them able to reunite our scattered detachments. we need larger minds, of broader culture and wider sympathies, to organise and rule the lands which we have subdued, and to lead on to further conquests. in the present state of natural science in britain, this evil is perhaps to be remedied only by providing a wider and deeper culture for our young men. few of our present workers have enjoyed that thorough training in mental as well as physical science, which is necessary to enable men even of great powers to take large and lofty views of the scheme of nature. hence we often find men who are fair workers in limited departments, reasoning most illogically, taking narrow and local views, elevating the exception into the rule, led away by baseless metaphysical subtleties, quarrelling with men who look at their specialties from a different point of view, and even striving and plotting for the advancement of their own hobbies. such defects certainly mar much of the scientific work now being done. in the more advanced walks of scientific research, they are to some extent neutralised by that free discussion which true science always fosters; though even here they sometimes vexatiously arrest the progress of truth, or open floodgates of error which it may require much labour to close. but in public lectures and popular publications they run riot, and are stimulated by the mistaken opposition of narrow-minded good men, by the love of the new and sensational, and by the rivalry of men struggling for place and position. to launch a clever and startling fallacy which will float for a week and stir up a hard fight, seems almost as great a triumph as the discovery of an important fact or law; and the honest student is distracted with the multitude of doctrines, and hustled aside by the crowd of ambitious groundlings. the only remedy in the case is a higher and more general scientific education; and yet i do not wonder that many good men object to this, simply because of the difficulty of finding honest and competent teachers, themselves well grounded in their subjects, and free from that too common insanity of specialists and half-educated men, which impels them to run amuck at everything that does not depend on their own methods of research. this is a difficulty which can be met in our time only by the general good sense and right feeling of the community taking a firm hold of the matter, and insisting on the organization and extension of the higher scientific education, as well as that of a more elementary character, under the management of able and sane men. yet even if not so counteracted, present follies will pass away, and a new and better state of natural science will arise in the future, by its own internal development. science cannot long successfully isolate itself from god. its life lies in the fact that it is the exponent of the plans and works of the great creative will. it must, in spite of itself, serve his purposes, by dispelling blighting ignorance and superstition, by lighting the way to successive triumphs of human skill over the powers of nature, and by guarding men from the evils that flow from infringement of natural laws. and it cannot fail, as it approaches nearer to the boundaries of that which may be known by finite minds, to be humbled by the contemplation of the infinite, and to recognise therein that intelligence of which the human mind is but the image and shadow. it may be that theologians also are needed who shall be fit to take the place of moses to our generation, in teaching it again the very elements of natural theology; but let them not look upon science as a cold and godless demon, holding forth to the world a poisoned cup cunningly compounded of truth and falsehood; but rather as the natural ally and associate of the gospel of salvation. the matter is so put in one of those visions which close the canon of revelation, when the prophet sees a mighty angel having the "everlasting gospel to preach;" but he begins his proclamation by calling on men to "worship him _that made heaven and earth and the sea and the fountains of waters_." men must know god as the creator even before they seek him as a benefactor and redeemer. thus religion must go hand in hand with all true and honest science. in this way only may we look forward to a time when a more exact and large-minded science shall be in perfect accord with a more pure and spiritual christianity, when the natural and the spiritual shall be seen to be the necessary complements of each other, and when we shall hear no more of reconciliations between science and theology, because there will be no quarrels to reconcile. already, even in the present chaos of scientific and religious opinion, indications can be seen by the observant, that the divine spirit of order is breathing on the mass, and will evolve from it new and beautiful worlds of mental and spiritual existence. chapter xiv. primitive man. considered with reference to modern theories as to his origin. the geological record, as we have been reading it, introduces us to primitive man, but gives us no distinct information as to his origin. tradition and revelation have, it is true, their solutions of the mystery, but there are, and always have been, many who will not take these on trust, but must grope for themselves with the taper of science or philosophy into the dark caverns whence issue the springs of humanity. in former times it was philosophic speculation alone which lent its dim and uncertain light to these bold inquirers; but in our day the new and startling discoveries in physics, chemistry, and biology have flashed up with an unexpected brilliancy, and have at least served to dazzle the eyes and encourage the hopes of the curious, and to lead to explorations more bold and systematic then any previously undertaken. thus has been born amongst us, or rather renewed, for it is a very old thing, that evolutionist philosophy, which has been well characterised as the "baldest of all the philosophies which have sprung up in our world," and which solves the question of human origin by the assumption that human nature exists potentially in mere inorganic matter, and that a chain of spontaneous derivation connects incandescent molecules or star-dust with the world, and with man himself. this evolutionist doctrine is itself one of the strangest phenomena of humanity. it existed, and most naturally, in the oldest philosophy and poetry, in connection with the crudest and most uncritical, attempts of the human mind to grasp the system of nature; but that in our day a system destitute of any shadow of proof, and supported merely by vague analogies and figures of speech, and by the arbitrary and artificial coherence of its own parts, should be accepted as a philosophy, and should find able adherents to string upon its thread of hypotheses our vast and weighty stores of knowledge, is surpassingly strange. it seems to indicate that the accumulated facts of our age have gone altogether beyond its capacity for generalisation; and but for the vigour which one sees everywhere, it might be taken as an indication that the human mind has fallen into a state of senility, and in its dotage mistakes for science the imaginations which were the dreams of its youth. in many respects these speculations are important and worthy of the attention of thinking men. they seek to revolutionise the religious beliefs of the world, and if accepted would destroy most of the existing theology and philosophy. they indicate tendencies among scientific thinkers, which, though probably temporary, must, before they disappear, descend to lower strata, and reproduce themselves in grosser forms, and with most serious effects on the whole structure of society. with one class of minds they constitute a sort of religion, which so far satisfies the craving for truths higher then those which relate to immediate wants and pleasures. with another and perhaps larger class, they are accepted as affording a welcome deliverance from all scruples of conscience and fears of a hereafter. in the domain of science evolutionism has like tendencies. it reduces the position of man, who becomes a descendant of inferior animals, and a mere term in a series whose end is unknown. it removes from the study of nature the ideas of final cause and purpose; and the evolutionist, instead of regarding the world as a work of consummate plan, skill, and adjustment, approaches nature as he would a chaos of fallen rocks, which may present forms of castles and grotesque profiles of men and animals, but they are all fortuitous and without significance. it obliterates the fine perception of differences from the mind of the naturalist, and resolves all the complicated relations of living things into some simple idea of descent with modification. it thus destroys the possibility of a philosophical classification, reducing all things to a mere series, and leads to a rapid decay in systematic zoology and botany, which is already very manifest among the disciples of spencer and darwin in england. the effect of this will be, if it proceeds further, in a great degree to destroy the educational value and popular interest attaching to these sciences, and to throw them down at the feet of a system of debased metaphysics. as redeeming features in all this, are the careful study of varietal forms, and the inquiries as to the limits of species, which have sprung from these discussions, and the harvest of which will be reaped by the true naturalists of the future. thus these theories as to the origin of men and animals and plants are full of present significance, and may be studied with profit by all; and in no part of their applications more usefully then in that which relates to man. let us then inquire,-- . what is implied in the idea of evolution as applied to man? . what is implied in the idea of creation? . how these several views accord with what we actually know as the result of scientific investigation? the first and second of these questions may well occupy the whole of this chapter, and we shall be able merely to glance at their leading aspects. in doing so, it may be well first to place before us in general terms the several alternatives which evolutionists offer, as to the mode in which the honour of an origin from apes or ape-like animals can be granted to us, along with the opposite view as to the independent origin of man which have been maintained either on scientific or scriptural grounds. all the evolutionist theories of the origin of man depend primarily on the possibility of his having been produced from some of the animals more closely allied to him, by the causes now in operation which lead to varietal forms, or by similar causes which have been in operation; and some attach more and others less weight to certain of these causes, or gratuitously suppose others not actually known. of such causes of change some are internal and others external to the organism. with respect to the former, one school assumes an innate tendency in every species to change in the course of time.[av] another believes in exceptional births, either in the course of ordinary generation or by the mode of parthenogenesis.[aw] another refers to the known facts of reproductive accelleration or retardation observed in some humble creatures.[ax] new forms arising in any of these ways or fortuitously, may, it is supposed, be perpetuated and increased and further improved by favouring external circumstances and the effort of the organism to avail itself of these,[ay] or by the struggle for existence and the survival of the fittest.[az] [av] parsons, owen. [aw] mivart, ferris. [ax] hyatt and cope. [ay] lamarck, etc. [az] darwin, etc. on the other hand, those who believe in the independent origin of man admit the above causes as adequate only to produce mere varieties, liable to return into the original stock. they may either hold that man has appeared as a product of special and miraculous creation, or that he has been created mediately by the operation of forces also concerned in the production of other animals, but the precise nature of which is still unknown to us; or lastly, they may hold what seems to be the view favoured by the book of genesis, that his bodily form is a product of mediate creation and his spiritual nature a direct emanation from his creator. the discussion of all these rival theories would occupy volumes, and to follow them into details would require investigations which have already bewildered many minds of some scientific culture. further, it is the belief of the writer that this plunging into multitudes of details has been fruitful of error, and that it will be a better course to endeavour to reach the root of the matter by looking at the foundations of the general doctrine of evolution itself, and then contrasting it with its rival. taking, then, this broad view of the subject, two great leading alternatives are presented to us. either man is an independent product of the will of a higher intelligence, acting directly or through the laws and materials of his own institution and production, or he has been produced by an unconscious evolution from lower things. it is true that many evolutionists, either unwilling to offend, or not perceiving the logical consequences of their own hypothesis, endeavour to steer a middle course, and to maintain that the creator has proceeded by way of evolution. but the bare, hard logic of spencer, the greatest english authority on evolution, leaves no place for this compromise, and shows that the theory, carried out to its legitimate consequences, excludes the knowledge of a creator and the possibility of his work. we have, therefore, to choose between evolution and creation; bearing in mind, however, that there may be a place in nature for evolution, properly limited, as well as for other things, and that the idea of creation by no means excludes law and second causes. limiting ourselves in the first place to theories of evolution, and to these as explaining the origin of species of living beings, and especially of man, we naturally first inquire as to the basis on which they are founded. now no one pretends that they rest on facts actually observed, for no one has ever observed the production of even one species. nor do they even rest, like the deductions of theoretical geology, on the extension into past time of causes of change now seen to be in action. their probability depends entirely on their capacity to account hypothetically for certain relations of living creatures to each other, and to the world without; and the strongest point of the arguments of their advocates is the accumulation of cases of such relations supposed to be accounted for. such being the kind of argument with which we have to deal, we may first inquire what we are required to believe as conditions of the action of evolution, and secondly, to what extent it actually does explain the phenomena. in the first place, as evolutionists, we are required to assume certain forces, or materials, or both, with which evolution shall begin. darwin, in his origin of species, went so far as to assume the existence of a few of the simpler types of animals; but this view, of course, was only a temporary resting-place for his theory. others assume a primitive protoplasm, or physical basis of life, and arbitrarily assigning to this substance properties now divided between organised and unorganised, and between dead and living matter, find no difficulty in deducing all plants and animals from it. still, even this cannot have been the ultimate material. it must have been evolved from something. we are thus brought back to certain molecules of star-dust, or certain conflicting forces, which must have had self-existence, and must have potentially included all subsequent creatures. otherwise, if with spencer we hold that god is "unknowable" and creation "unthinkable," we are left suspended on nothing over a bottomless void, and must adopt as the initial proposition of our philosophy, that all things were made out of nothing, and by nothing; unless we prefer to doubt whether anything exists, and to push the doctrine of relativity to the unscientific extreme of believing that we can study the relations of things non-existent or unknown. so we must allow the evolutionist some small capital to start with; observing, however, that self-existent matter in a state of endless evolution is something of which we cannot possibly have any definite conception. being granted thus much, the evolutionist next proceeds to demand that we shall also believe in the indefinite variability of material things, and shall set aside all idea that there is any difference in kind between the different substances which we know. they must all be mutually convertible, or at least derivable from some primitive material. it is true that this is contrary to experience. the chemist holds that matter is of different kinds, that one element cannot be converted into another; and he would probably smile if told that, even in the lapse of enormous periods of time, limestone could be evolved out of silica. he may think that this is very different from the idea that a snail can be evolved from an oyster, or a bird from a reptile. but the zoologist will inform him that species of animals are only variable within certain limits, and are not transmutable, in so far as experience and experiment are concerned. they have their allotropic forms, but cannot be changed into one another. but if we grant this second demand, the evolutionist has a third in store for us. we must also admit that by some inevitable necessity the changes of things must in the main take place in one direction, from the more simple to the more complex, from the lower to the higher. at first sight this seems not only to follow from the previous assumptions, but to accord with observation. do not all living things rise from a simpler to a more complex state? has not the history of the earth displayed a gradually increasing elevation and complexity? but, on the other hand, the complex organism becoming mature, resolves itself again into the simple germ, and finally is dissolved into its constituent elements. the complex returns into the simple, and what we see is not an evolution, but a revolution. in like manner, in geological time, the tendency seems to be ever to disintegration and decay. this we see everywhere, and find that elevation occurs only by the introduction of new species in a way which is not obvious, and which may rather imply the intervention of a cause from without; so that here also we are required to admit as a general principle what is contrary to experience. if, however, we grant the evolutionist these postulates, we must next allow him to take the facts of botany and zoology out of their ordinary connection, and thread them like a string of beads, as herbert spencer has done in his "biology," on the threefold cord thus fashioned. this done, we next find, as might have been expected, certain gaps or breaks which require to be cunningly filled with artificial material, in order to give an appearance of continuity to the whole. the first of these gaps which we notice is that between dead and living matter. it is easy to fill this with such a term as protoplasm, which includes matter both dead and living, and so to ignore this distinction; but practically we do not yet know as a possible thing the elevation of matter, without the agency of a previous living organism, from that plane in which it is subject merely to physical force, and is unorganised, to that where it becomes organised, and lives. under that strange hypothesis of the origin of life from meteors, with which sir william thomson closed his address at a late meeting of the british association, there was concealed a cutting sarcasm which the evolutionists felt. it reminded them that the men who evolve all things from physical forces do not yet know how these forces can produce the phenomena of life even in its humblest forms. it is true that the scientific world has been again and again startled by the announcement of the production of some of the lowest forms of life, either from dead organic matter, or from merely mineral substances; but in every case heretofore the effort has proved as vain as the analogies attempted to be set up between the formation of crystals and that of organized tissues are fallacious. a second gap is that which separates vegetable and animal life. these are necessarily the converse of each other, the one deoxidizes and accumulates, the other oxidizes and expends. only in reproduction or decay does the plant simulate the action of the animal, and the animal never in its simplest forms assumes the functions of the plant. those obscure cases in the humbler spheres of animal and vegetable life which have been supposed to show a union of the two kingdoms, disappear on investigation. this gap can, i believe, be filled up only by an appeal to our ignorance. there may be, or may have been, some simple creature unknown to us, on the extreme verge of the plant kingdom, that was capable of passing the limit and becoming an animal. but no proof of this exists. it is true that the primitive germs of many kinds of humble plants and animals are so much alike, that much confusion has arisen in tracing their development. it is also true that some of these creatures can subsist under very dissimilar conditions, and in very diverse states, and that under the specious name of biology,[ba] we sometimes find a mass of these confusions, inaccurate observations and varietal differences made to do duty for scientific facts. but all this does not invalidate the grand primary distinction between the animal and the plant, which should be thoroughly taught and illustrated to all young naturalists, as one of the best antidotes to the fallacies of the evolutionist school. [ba] it is doubtful whether men who deny the existence of vital force have a right to call their science "biology," any more then atheists have to call their doctrine "theology;" and it is certain that the assumption of a science of biology as distinct from phytology and zoology, or including both, is of the nature of a "pious fraud" on the part of the more enlightened evolutionists. the objections stated in the text, to what have been called archebiosis and heterogenesis seem perfectly applicable, in so far as i can judge from a friendly review by wallace, to the mass of heterogeneous material accumulated by dr. bastian in his recent volumes. the conclusions of this writer, would also, if established, involve evolution in a fatal _embarras des richesses_, by the hourly production during all geological time, of millions of new forms all capable of indefinite development. a third is that between any species of animal or plant and any other species. it was this gap, and this only, which darwin undertook to fill up by his great work on the origin of species, but, notwithstanding the immense amount of material thus expended, it yawns as wide as ever, since it must be admitted that no case has been ascertained in which an individual of one species has transgressed the limits between it and other species. however extensive the varieties produced by artificial breeding, the essential characters of the species remain, and even its minor characters may be reproduced, while the barriers established in nature between species by the laws of their reproduction, seem to be absolute. with regard to species, however, it must be observed that naturalists are not agreed as to what constitutes a species. many so-called species are probably races, or varieties, and one benefit of these inquiries has been to direct attention to the proper discrimination of species from varieties among animals and plants. the loose discrimination of species, and the tendency to multiply names, have done much to promote evolutionist views; but the researches of the evolutionists themselves have shown that we must abandon transmutation of true species as a thing of the present; and if we imagine it to have occurred, must refer it to the past. another gap is that between the nature of the animal and the self-conscious, reasoning, moral nature of man. we not only have no proof that any animal can, by any force in itself, or by any merely physical influences from without, rise to such a condition; but the thing is in the highest degree improbable. it is easy to affirm, with the grosser materialists, that thought is a secretion of brain, as bile is of the liver; but a moment's thought shows that no real analogy obtains between the cases. we may vaguely suppose, with darwin, that the continual exercise of such powers as animals possess, may have developed those of man. but our experience of animals shows that their intelligence differs essentially from that of man, being a closed circle ever returning into itself, while that of man is progressive, inventive, and accumulative, and can no more be correlated with that of the animal then the vital phenomena of the animal with those of the plant. nor can the gap between the higher religious and moral sentiments of man, and the instinctive affections of the brutes, be filled up with that miserable ape imagined by lubbock, which, crossed in love, or pining with cold and hunger, conceived, for the first time in its poor addled pate, "the dread of evil to come," and so became the father of theology. this conception, which darwin gravely adopts, would be most ludicrous, but for the frightful picture which it gives of the aspect in which religion appears to the mind of the evolutionist. the reader will now readily perceive that the simplicity and completeness of the evolutionist theory entirely disappear when we consider the unproved assumptions on which it is based, and its failure to connect with each other some of the most important facts in nature: that, in short, it is not in any true sense a philosophy, but merely an arbitrary arrangement of facts in accordance with a number of unproved hypotheses. such philosophies, "falsely so called," have existed ever since man began to reason on nature, and this last of them is one of the weakest and most pernicious of the whole. let the reader take up either of darwin's great books, or spencer's "biology," and merely ask himself as he reads each paragraph, "what is assumed here and what is proved?" and he will find the whole fabric melt away like a vision. he will find, however, one difference between these writers. darwin always states facts carefully and accurately, and when he comes to a difficulty tries to meet it fairly. spencer often exaggerates or extenuates with reference to his facts, and uses the arts of the dialectician where argument fails. many naturalists who should know better are puzzled with the great array of facts presented by evolutionists; and while their better judgment causes them to doubt as to the possibility of the structures which they study being produced by such blind and material processes, are forced to admit that there must surely be something in a theory so confidently asserted, supported by so great names, and by such an imposing array of relations which it can explain. they would be relieved from their weak concessions were they to study carefully a few of the instances adduced, and to consider how easy it is by a little ingenuity to group undoubted facts around a false theory. i could wish to present here illustrations of this, which abound in every part of the works i have referred to, but space will not permit. one or two must suffice. the first may be taken from one of the strong points often dwelt on by spencer in his "biology."[bb] [bb] "principles of biology," § . "but the experiences which most clearly illustrate to us the process of general evolution are our experiences of special evolution, repeated in every plant and animal. each organism exhibits, within a short space of time, a series of changes which, when supposed to occupy a period indefinitely great and to go on in various ways instead of one, may give us a tolerably clear conception of organic evolution in general. in an individual development we have compressed into a comparatively infinitesimal space a series of metamorphoses equally vast with those which the hypothesis of evolution assumes to have taken place during those unmeasurable epochs that the earth's crust tells us of. a tree differs from a seed immeasurably in every respect--in bulk, in structure, in colour, in form, in specific gravity, in chemical composition: differs so greatly that no visible resemblance of any kind can be pointed out between them. yet is the one changed in the course of a few years into the other; changed so gradually that at no moment can it be said, 'now the seed ceases to be and the tree exists.' what can be more widely contrasted then a newly-born child and the small gelatinous spherule constituting the human ovum? the infant is so complex in structure that a cyclopædia is needed to describe its constituent parts. the germinal vesicle is so simple that it may be defined in a line.... if a single cell under appropriate conditions becomes a man in the space of a few years, there can surely be no difficulty in understanding how, under appropriate conditions, a cell may in the course of untold millions of years give origin to the human race." "it is true that many minds are so unfurnished with those experiences of nature, out of which this conception is built, that they find difficulty in forming it.... to such the hypothesis that by any series of changes a protozoan should ever give origin to a mammal seems grotesque--as grotesque as did galileo's assertion of the earth's movement seem to the aristoteleans; or as grotesque as the assertion of the earth's sphericity seems now to the new zealanders." i quote the above as a specimen of evolutionist reasoning from the hand of a master, and as referring to one of the corner-stones of this strange philosophy. i may remark with respect to it, in the first place, that it assumes those "conditions" of evolution to which i have already referred. in the second place, it is full of inaccurate statements of fact, all in a direction tending to favour the hypothesis. for example, a tree does not differ "immeasurably" from a seed, especially if the seed is of the same species of tree, for the principal parts of the tree and its principal chemical constituents already exist and can be detected in the seed, and unless it were so, the development of the tree from the seed could not take place. besides, the seed itself is not a thing self-existent or fortuitous. the production of a seed without a previous tree of the same kind is quite as difficult to suppose as the production of a tree without a previous seed containing its living embryo. in the third place, the whole argument is one of analogy. the germ becomes a mature animal, passing through many intermediate stages, therefore the animal may have descended from some creature which when mature was as simple as the germ. the value of such an analogy depends altogether on the similarity of the "conditions" which, in such a case, are really the efficient causes at work. the germ of a mammal becomes developed by the nourishment supplied from the system of a parent, which itself produced the germ, and into whose likeness the young animal is destined to grow. these are the "appropriate conditions" of its development. but when our author assumes from this other "appropriate conditions," by which an organism, which on the hypothesis is not a germ but a mature animal, shall be developed into the likeness, of something different from its parent, he oversteps the bounds of legitimate analogy. further, the reproduction of the animal, as observed, is a closed series, beginning at the embryo and returning thither again; the evolution attempted to be established is a progressive series going on from one stage to another. a reproductive circle once established obeys certain definite laws, but its origin, or how it can leave its orbit and revolve in some other, we cannot explain without the introduction of some new efficient cause. the one term of the analogy is a revolution, and the other is an evolution. the revolution within the circle of the reproduction of the species gives no evidence that at some point the body will fly off at a tangent, and does not even inform us whether it is making progress in space. even if it is so making progress, its orbit of revolution may remain the same. but it may be said the reproduction of the species is not in a circle but in a spiral. within the limit of experience it is not so, since, however it may undulate, it always returns into itself. but supposing it to be a spiral, it may ascend or descend, or expand and contract; but this does not connect it with other similar spirals, the separate origin of which is to be separately accounted for. i have quoted the latter part of the passage because it is characteristic of evolutionists to decry the intelligence of those who differ from them. now it is fair to admit that it requires some intelligence and some knowledge of nature to produce or even to understand such analogies as those of mr. spencer and his followers, but it is no less true that a deeper insight into the study of nature may not only enable us to understand these analogies, but to detect their fallacies. i am sorry to say, however, that at present the hypothesis of evolution is giving so strong a colouring to much of popular and even academic teaching, more especially in the easy and flippant conversion of the facts of embryology into instances of evolution on the plan of the above extract, that the spencerians may not long have to complain of want of faith and appreciation on the part of the improved apes whom they are kind enough to instruct as to their lowly origin. the mention of "appropriate conditions" in the above extract reminds me of another fatal objection to evolution which its advocates continually overlook. an animal or plant advancing from maturity to the adult state is in every stage of its progress a complete and symmetrical organism, correlated in all its parts and adapted to surrounding conditions. suppose it to become modified in any way, to ever so small an extent, the whole of these relations are disturbed. if the modification is internal and spontaneous, there is no guarantee that it will suit the vastly numerous external agencies to which the creature is subjected. if it is produced by agencies from without, there is no guarantee that it will accord with the internal relations of the parts modified. the probabilities are incalculably great against the occurrence of many such disturbances without the breaking up altogether of the nice adjustment of parts and conditions. this is no doubt one reason of the extinction of so many species in geological time, and also of the strong tendency of every species to spring back to its normal condition when in any way artificially caused to vary. it is also connected with the otherwise mysterious law of the constant transmission of all the characters of the parent. spencer and darwin occasionally see this difficulty, though they habitually neglect it in their reasonings. spencer even tries to turn one part of it to account as follows:-- "suppose the head of a mammal to become very much more weighty--what must be the indirect results? the muscles of the neck are put to greater exertions; and the vertebræ have to bear additional tensions and pressures caused both by the increased weight of the head and the stronger contraction of muscles that support and move the head." he goes on to say that the processes of the vertebrae will have augmented strains put upon them, the thoracic region and fore limbs will have to be enlarged, and even the hind limbs may require modification to facilitate locomotion. he concludes: "any one who compares the outline of the bison with that of its congener, the ox, will clearly see how profoundly a heavier head affects the entire osseous and muscular system." we need not stop to mention the usual inaccuracies as to facts in this paragraph, as, for example, the support of the head being attributed to muscles alone, without reference to the strong elastic ligament of the neck. we may first notice the assumption that an animal can acquire a head "very much more weighty" then that which it had before, a very improbable supposition, whether as a monstrous birth dr as an effect of external conditions after birth. but suppose this to have occurred, and what is even less likely, that the very much heavier head is an advantage in some way, what guarantee can evolution give us that the number of other modifications required would take place simultaneously with this acquisition! it would be easy to show that this would depend on the concurrence of hundreds of other conditions within and without the animal, all of which must co-operate to produce the desired effect, if indeed they could produce this effect even by their conjoint action, a power which the writer, it will be observed, quietly assumes, as well as the probability of the initial change in the head. finally, the naivete with which it is assumed that the bison and the ox are examples of such an evolution, would be refreshing in these artificial days, if instances of it did not occur in almost every page of the writings of evolutionists. it would only weary the reader to follow evolution any further into details, especially as my object in this chapter is to show that generally, and as a theory of nature and of man, it has no good foundation; but we should not leave the subject without noting precisely the derivation of man according to this theory; and for this purpose i may quote darwin's summary of his conclusions on the subject.[bc] [bc] "descent of man," part ii., ch. . "man," says mr. darwin, "is descended from a hairy quadruped, furnished with a tail and pointed ears, probably arboreal in its habits, and an inhabitant of the old world. this creature, if its whole structure had been examined by a naturalist, would have been classed amongst the quadrumana, as surely as would the common, and still more ancient, progenitor of the old and new world monkeys. the quadrumana and all the higher mammals are probably derived from an ancient marsupial animal; and this, through a long line of diversified forms, either from some reptile-like or some amphibian-like creature, and this again from some fish-like animal. in the dim obscurity of the past we can see that the early progenitor of all the vertebrata must have been an aquatic animal, provided with branchiæ, with the two sexes united in the same individual, and with the most important organs of the body (such as the brain and heart) imperfectly developed. this animal seems to have been more like the larvæ of our existing marine ascidians then any other form known." the author of this passage, in condescension to our weakness of faith, takes us no further back then to an ascidian, or "sea-squirt," the resemblance, however, of which to a vertebrate animal is merely analogical, and, though a very curious case of analogy, altogether temporary and belonging to the young state of the creature, without affecting its adult state or its real affinities with other mollusks. in order, however, to get the ascidian itself, he must assume all the "conditions" already referred to in the previous part of this article, and fill most of the gaps. he has, however, in the "origin of species" and "descent of man," attempted merely to fill one of the breaks in the evolutionary series, that between distinct species, leaving us to receive all the rest on mere faith. even in respect to the question of species, in all the long chain between the ascidian and the man, he has not certainly established one link; and in the very last change, that from the ape-like ancestor, he equally fails to satisfy us as to matters so trivial as the loss of the hair, which, on the hypothesis, clothed the pre-human back, and on matters so weighty as the dawn of human reason and conscience. we thus see that evolution as an hypothesis has no basis in experience or in scientific fact, and that its imagined series of transmutations has breaks which cannot be filled. we have now to consider how it stands with the belief that man has been created by a higher power. against this supposition the evolutionists try to create a prejudice in two ways. first, they maintain with herbert spencer that the hypothesis of creation is inconceivable, or, as they say, "unthinkable;" an assertion which, when examined, proves to mean only that we do not know perfectly the details of such an operation, an objection equally fatal to the origin either of matter or life, on the hypothesis of evolution. secondly, they always refer to creation as if it must be a special miracle, in the sense of a contravention of or departure from ordinary natural laws; but this is an assumption utterly without proof, since creation may be as much according to law as evolution, though in either case the precise laws involved may be very imperfectly known. how absurd, they say, to imagine an animal created at once, fully formed, by a special miracle, instead of supposing it to be slowly elaborated through, countless ages of evolution. to darwin the doctrine of creation is but "a curious illustration of the blindness of preconceived opinion." "these authors," he says, "seem no more startled at a miraculous act of creation then at an ordinary birth; but do they really believe that at innumerable periods in the earth's history, certain elemental atoms have been commanded suddenly to flash into living tissues?" darwin, with all his philosophic fairness, sometimes becomes almost spencerian in his looseness of expression; and in the above extract, the terms "miraculous," "innumerable," "elemental atoms," "suddenly," and "flash," all express ideas in no respect necessary to the work of creation. those who have no faith in evolution as a cause of the production of species, may well ask in return how the evolutionist can prove that creation must be instantaneous, that it must follow no law, that it must produce an animal fully formed, that it must be miraculous. in short, it is a portion of the policy of evolutionists to endeavour to tie down their opponents to a purely gratuitous and ignorant view of creation, and then to attack them in that position. what, then, is the actual statement of the theory of creation as it may be held by a modern man of science? simply this; that all things have been produced by the supreme creative will, acting either directly or through the agency of the forces and materials of his own production. this theory does not necessarily affirm that creation is miraculous, in the sense of being contrary to or subversive of law; law and order are as applicable to creation as to any other process. it does not contradict the idea of successive creations. there is no necessity that the process should be instantaneous and without progression. it does not imply that all kinds of creation are alike. there may be higher and lower kinds. it does not exclude the idea of similarity or dissimilarity of plan and function as to the products of creation. distinct products of creation may be either similar to each other in different degrees, or dissimilar. it does not even exclude evolution or derivation to a certain extent: anything once created may, if sufficiently flexible and elastic, be evolved or involved in various ways. indeed, creation and derivation may, rightly understood, be complementary to each other. created things, unless absolutely unchangeable, must be more or less modified by influences from within and from without, and derivation or evolution may account for certain subordinate changes of things already made. man, for example, may be a product of creation, yet his creation may have been in perfect harmony with those laws of procedure which the creator has set for his own operations. he may have been preceded by other creations of things more or less similar or dissimilar. he may have been created by the same processes with some or all of these, or by different means. his body may have been created in one way, his soul in another. he may, nay, in all probability would be, part of a plan of which some parts would approach very near to him in structure or functions. after his creation, spontaneous culture and outward circumstances may have moulded him into varieties, and given him many different kinds of speech and of habits. these points are so obvious to common sense that it would be quite unnecessary to insist on them, were they not habitually overlooked or misstated by evolutionists. the creation hypothesis is also free from some of the difficulties of evolution. it avoids the absurdity of an eternal progression from the less to the more complex. it provides in will, the only source of power actually known to us by ordinary experience, an intelligible origin of nature. it does not require us to contradict experience by supposing that there are no differences of kind or essence in things. it does not require us to assume, contrary to experience, an invariable tendency to differentiate and improve. it does not exact the bridging over of all gaps which may be found between the several grades of beings which exist or have existed. why, then, are so many men of science disposed to ignore altogether this view of the matter? mainly, i believe, because, from the training of many of them, they are absolutely ignorant of the subject, and from their habits of thought have come to regard physical force and the laws regulating it as the one power in nature, and to relegate all spiritual powers or forces, or, as they have been taught to regard them, "supernatural" things, to the domain of the "unknowable." perhaps some portion of the difficulty may be got over by abandoning altogether the word "supernatural," which has been much misused, and by holding nature to represent the whole cosmos, and to include both the _physical_ and the _spiritual_, both of them in the fullest sense subject to law, but each to the law of its own special nature. i have read somewhere a story of some ignorant orientals who were induced to keep a steam-engine supplied with water by the fiction that it contained a terrible _djin_, or demon, who, if allowed to become thirsty, would break out and destroy them all. had they been enabled to discard this superstition, and to understand the force of steam, we can readily imagine that they would now suppose they knew the whole truth, and might believe that any one who taught them that the engine was a product of intelligent design, was only taking them back to the old doctrine of the thirsty demon of the boiler. this is, i think, at present, the mental condition of many scientists with reference to creation. here we come to the first demand which the doctrine of creation makes on us by way of premises. in order that there may be creation there must be a primary self-existent spirit, whose will is supreme. the evolutionist cannot refuse to admit this on as good ground as that on which we hesitate to receive the postulates of his faith. it is no real objection to say that a god can be known to us only partially, and, with reference to his real essence, not at all; since, even if we admit this, it is no more then can be said of matter and force. i am not about here to repeat any of the ordinary arguments for the existence of a spiritual first cause, and creator of all things, but it may be proper to show that this assumption is not inconsistent with experience, or with the facts and principles of modern science. the statement which i would make on this point shall be in the words of a very old writer, not so well known as he should be to many who talk volubly enough about antagonisms between science and christianity: "that which is known of god is manifest in them (in men), for god manifested it unto them. for since the creation of the world his invisible things, even his eternal power and divinity are plainly seen, being perceived by means of things that are made."[bd] the statement here is very precise. certain things relating to god are manifest within men's minds, and are proved by the evidence of his works; these properties of god thus manifested being specially his power or control of all forces, and his divinity or possession of a nature higher then ours. the argument of the writer is that all heathens know this; and, as a matter of fact, i believe it must be admitted even by those most sceptical on such points, that some notion of a divinity has been derived from nature by men of all nations and tribes, if we except, perhaps, a few enlightened positivists of this nineteenth century whom excess of light has made blind. "if the light that is in man be darkness, how great is that darkness." but then this notion of a god is a very old and primitive one, and spencer takes care to inform us that "first thoughts are either wholly out of harmony with things, or in very incomplete harmony with them," and consequently that old beliefs and generally diffused notions are presumably wrong. [bd] paul's epistle to the romans, chap i. is it true, however, that the modern knowledge of nature tends to rob it of a spiritual first cause? one can conceive such a tendency, if all our advances in knowledge had tended more and more to identify force with matter in its grosser forms, and to remove more and more from our mental view those powers which are not material; but the very reverse of this is the case. modern discovery has tended more and more to attach importance to certain universally diffused media which do not seem to be subject to the laws of ordinary matter, and to prove at once the protean character and indestructibility of forces, the aggregate of which, as acting in the universe, gives us our nearest approach to the conception of physical omnipotence. this is what so many of our evolutionists mean when they indignantly disclaim materialism. they know that there is a boundless energy beyond mere matter, and of which matter seems the sport and toy. could they conceive of this energy as the expression of a personal will, they would become theists. man himself presents a microcosm of matter and force, raised to a higher plane then that of the merely chemical and physical. in him we find not merely that brain and nerve force which is common to him and lower animals, and which exhibits one of the most marvellous energies in nature, but we have the higher force of will and intellect, enabling him to read the secrets of nature, to seize and combine and utilize its laws like a god, and like a god to attain to the higher discernment of good and evil. nay, more, this power which resides within man rules with omnipotent energy the material organism, driving its nerve forces until cells and fibres are worn out and destroyed, taxing muscles and tendons till they break, impelling its slave the body even to that which will bring injury and death itself. surely, what we thus see in man must be the image and likeness of the great spirit. we can escape from this conclusion only by one or other of two assumptions, either of which is rather to be called a play upon words then a scientific theory. we may, with a certain class of physicists and physiologists, confine our attention wholly to the fire and the steam, and overlook the engineer. we may assume that with protoplasm and animal electricity, for example, we can dispense with life, and not only with life but with spirit also. yet he who regards vitality as an unmeaning word; and yet speaks of "living protoplasm," and "dead protoplasm," and affirms that between these two states, so different in their phenomena, no chemical or physical difference exists, is surely either laughing at us, or committing himself to what the duke of argyll calls a philosophical bull; and he who shows us that electrical discharges are concerned in muscular contraction, has just as much proved that there is no need of life or spirit, as the electrician who has explained the mysteries of the telegraph has shown that there can be no need of an operator. or we may, turning to the opposite extreme, trust to the metaphysical fallacy of those who affirm that neither matter, nor force, nor spirit, need concern them, for that all are merely states of consciousness in ourselves. but what of the conscious self this self which thinks, and which is in relation with surroundings which it did not create, and which presumably did not create it? and what is the unknown third term which must have been the means of setting up these relations? here again our blind guides involve us in an absolute self-contradiction. thus we are thrown back on the grand old truth that man, heathen and savage, or christian and scientific, opens his eyes on nature and reads therein both the physical and the spiritual, and in connection with both of these the power and divinity of an almighty creator. he may at first have many wrong views both of god and of his works, but as he penetrates further into the laws of matter and mind, he attains more just conceptions of their relations to the great centre and source of all, and instead of being able to dispense with creation, he hopes to be able at length to understand its laws and methods. if unhappily he abandons this high ambition, and contents himself with mere matter and physical force, he cannot rise to the highest development either of science or philosophy. it may, however, be said that evolution may admit all this, and still be held as a scientific doctrine in connection with a modified belief in creation. the work of actual creation may have been limited to a few elementary types, and evolution may have done the rest. evolutionists may still be theists. we have already seen that the doctrine, as carried out to its logical consequences, excludes creation and theism. it may, however, be shown that even in its more modified forms, and when held by men who maintain that they are not atheists, it is practically atheistic, because excluding the idea of plan and design, and resolving all things into the action of unintelligent forces. it is necessary to observe this, because it is the half-way evolutionism which professes to have a creator somewhere behind it, that is most popular; though it is, if possible, more unphilosophical then that which professes to set out from absolute and eternal nonentity, or from self-existent star-dust containing all the possibilities of the universe. absolute atheists recognise in darwinism, for example, a philosophy which reduces all things to a "gradual summation of innumerable minute and accidental material operations," and in this they are more logical then those who seek to reconcile evolution with design. huxley, in his "lay sermons," referring to paley's argument for design founded on the structure of a watch, says that if the watch could be conceived to be a product of a less perfect structure improved by natural selection, it would then appear to be the "result of a method of trial and error worked by unintelligent agents, as likely as of the direct application of the means appropriate to that end, by an intelligent agent." this is a bold and true assertion of the actual relation of even this modified evolution to rational and practical theism, which requires not merely this god "afar off," who has set the stone of nature rolling and then turned his back upon it, but a present god, whose will is the law of nature, now as in times past. the evolutionist is really in a position of absolute antagonism to the idea of creation, even when held with all due allowance for the variations of created things within certain limits. perhaps paley's old illustration of the watch, as applied by huxley, may serve to show this as well as any other. if the imperfect watch, useless as a time-keeper, is the work of the contriver, and the perfection of it is the result of unintelligent agents working fortuitously, then it is clear that creation and design have a small and evanescent share in the construction of the fabric of nature. but is it really so? can we attribute the perfection of the watch to "accidental material operations" any more then the first effort to produce such an instrument? paley himself long ago met this view of the case, but his argument may be extended by the admissions and pleas of the evolutionists themselves. for example, the watch is altogether a mechanical thing, and this fact by no means implies that it could not be made by an intelligent and spiritual designer, yet this assumption that physical laws exclude creation and design turns up in almost every page of the evolutionists. paley has well shown that if the watch contained within itself machinery for making other watches, this would not militate against his argument. it would be so if it could be proved that a piece of metal had spontaneously produced an imperfect watch, and this a more perfect one, and so on; but this is precisely what evolutionists still require to prove with respect both to the watch and to man. on the other hand it is no argument for the evolution of the watch that there may be different kinds of watches, some more and others less perfect, and that ruder forms may have preceded the more perfect. this is perfectly compatible with creation and design. evolutionists, however, generally fail to make this distinction. nor would it be any proof of the evolution of the watch to find that, as spencer would say, it was in perfect harmony with its environment, as, for instance, that it kept time with the revolution of the earth, and contained contrivances to regulate its motion under different temperatures, unless it could be shown that the earth's motion and the changes of temperature had been efficient causes of the motion and the adjustments of the watch; otherwise the argument would look altogether in the direction of design. nor would it be fair to shut up the argument of design to the idea that the watch must have suddenly flashed into existence fully formed and in motion. it would be quite as much a creation if slowly and laboriously made by the hand of the artificer, or if more rapidly struck off by machinery; and if the latter, it would not follow that the machine which produced the watch was at all like the watch itself. it might have been something very different. finally, when spencer tries to cut at the root of the whole of this argument, by affirming that man has no more right to reason from himself with regard to his maker then a watch would have to reason from its own mechanical structure and affirm the like of its maker, he signally fails. if the watch had such power of reasoning, it would be more then mechanical, and would be intelligent like its maker; and in any case, if thus reasoning it came to the conclusion that it was a result of "accidental material operations," it would be altogether mistaken. nor would it be nearer the truth if it held that it was a product of spontaneous evolution from an imperfect and comparatively useless watch that had been made millions of years before. we have taken this illustration of the watch merely as given to us by huxley, and without in the least seeking to overlook the distinction between a dead machine and a living organism; but the argument for creation and design is quite as strong in the case of the latter, so long as it cannot be proved by actual facts to be a product of derivation from a distinct species. this has not been proved either in the care of man or any other species; and so long as it has not, the theory of creation and design is infinitely more rational and scientific then that of evolution in any of its forms. but all this does not relieve us from the question, how can species be created?--the same question put to paul by the sceptics of the first century with reference to the resurrection--"how are the dead raised, and with what bodies do they come?" i do not wish to evade this question, whether applied to man or to a microscopic animalcule, and i would answer it with the following statements:-- . the advocate of creation is in this matter in no worse position then the evolutionist. this we have already shown, and i may refer here to the fact that darwin himself assumes at least one primitive form of animal and plant life, and he is confessedly just as little able to imagine this one act of creation as any other that may be demanded of him. . we are not bound to believe that all groups of individual animals, which naturalists may call species, have been separate products of creation. man himself has by some naturalists been divided into several species; but we may well be content to believe the creation of one primitive form, and the production of existing races by variation. every zoologist and botanist who has studied any group of animals or plants with care, knows that there are numerous related forms passing into each other, which some naturalists might consider to be distinct species, but which it is certainly not necessary to regard as distinct products of creation. every species is more or less variable, and this variability may be developed by different causes. individuals exposed to unfavourable conditions will be stunted and depauperated; those in more favourable circumstances may be improved and enlarged. important changes may thus take place without transgressing the limits of the species, or preventing a return to its typical forms; and the practice of confounding these more limited changes with the wider structural and physiological differences which separate true species is much to be deprecated. animals which pass through metamorphoses, or which, are developed through the instrumentality of intermediate forms or "nurses"[be] are not only liable to be separated by mistake into distinct species, but they may, tinder certain circumstances, attain to a premature maturity, or may be fixed for a time or permanently in an immature condition. further, species, like individuals, probably have their infancy, maturity, and decay in geological time, and may present differences in these several stages. it is the remainder of true specific types left after all these sources of error are removed, that creation has to account for; and to arrive at this remainder, and to ascertain its nature and amount, will require a vast expenditure of skilful and conscientious labour. [be] mr. mungo ponton, in his book "the beginning," has based a theory of derivation on this peculiarity. . since animals and plants have been introduced upon our earth in long succession throughout geologic time, and this in a somewhat regular manner, we have a right to assume that their introduction has been in accordance with a law or plan of creation, and that this may have included the co-operation of many efficient causes, and may have differed in its application to different cases. this is a very old doctrine of theology, for it appears in the early chapters of genesis. there the first aquatic animals, and man, are said to have been "created;" plants are said to have been "brought forth by the land;" the mammalia are said to have been "made." in the more detailed account of the introduction of man in the second chapter of the same book, he is said to have been "formed of the dust of the ground;" and in regard to his higher spiritual life, to have had this "breathed into" him by god. these are very simple expressions, but they are very precise and definite in the original, and they imply a diversity in the creative work. further, this is in accordance with the analogy of modern science. how diverse are the modes of production and development of animals and plants, though all under one general law; and is it not likely that the modes of their first introduction on the earth were equally diverse? . our knowledge of the conditions of the origination of species, is so imperfect that we may possibly appear for some time to recede from, rather then to approach to, a solution of the question. in the infancy of chemistry, it was thought that chemical elements could be transmuted into each other. the progress of knowledge removed this explanation of their origin, and has as yet failed to substitute any other in its place. it may be the same with organic species. the attempt to account for them by derivation may prove fallacious, yet it may be some time before we turn the corner, should this be possible, and enter the path which actually leads up to their origin. lastly, in these circumstances our wisest course is to take individual species, and to inquire as to their history in time, and the probable conditions of their introduction. such investigations are now being made by many quiet workers, whose labours are comparatively little known, and many of whom are scarcely aware of the importance of what they are doing toward a knowledge of, at least, the conditions of creation, which is perhaps all that we can at present hope to reach. in the next chapter we shall try to sum up what is known as to man himself, in the conditions of his first appearance on our earth, as made known to us by scientific investigation, and explained on the theory of creation as opposed to evolution. chapter xv. primitive man. considered with reference to modern theories as to his origin (continued). in the previous chapter we have seen that, on general grounds, evolution as applied to man is untenable; and that the theory of creation is more rational and less liable to objection. we may now consider how the geological and zoological conditions of man's advent on the earth accord with evolution; and i think we shall find, as might be expected, that they oppose great if not fatal difficulties to this hypothesis. one of the first and most important facts with reference to the appearance of man, is that he is a very recent animal, dating no farther back in geological time then the post-glacial period, at the close of the tertiary and beginning of the modern era of geology. further, inasmuch as the oldest known remains of man occur along with those of animals which still exist, and the majority of which are probably not of older date, there is but slender probability that any much older human remains will ever be found. now this has a bearing on the question of the derivation of man, which, though it has not altogether escaped the attention of the evolutionists, has not met with sufficient consideration. perhaps the oldest; known human skull is that which has been termed the "engis" skull, from the cave of engis, in belgium. with reference to this skull, professor huxley has candidly admitted that it may have belonged to an individual of one of the existing faces of men. i have a cast of it on the same shelf with the skulls of some algonquin indians, from the aboriginal hochelaga, which preceded montreal; and any one acquainted with cranial characters would readily admit that the ancient belgian may very well have been an american indian; while on the other hand his head is not very dissimilar from that of some modern european races. this belgian man is believed to have lived before the mammoth and the cave bear had passed away, yet he does not belong to an extinct species or even variety of man. further, as stated in a previous chapter, pictet catalogues ninety-eight species of mammals which inhabited europe in the post-glacial period. of these fifty-seven still exist unchanged, and the remainder have disappeared. not one can be shown to have been modified into a new form, though some of them have been obliged, by changes of temperature and other conditions, to remove into distant and now widely separated regions. further, it would seem that all the existing european mammals extended back in geological time at least as far as man, so that since the post-glacial period no new species have been introduced in any way. here we have a series of facts of the most profound significance. fifty-seven parallel lines of descent nave in europe run on along with man, from the post-glacial period, without change or material modification of any kind. some of them extend without change even farther back. thus man and his companion-mammals present a series of lines, not converging as if they pointed to some common progenitor, but strictly parallel to each other. in other words, if they are derived forms, their point of derivation from a common type is pushed back infinitely in geological time. the absolute duration of the human species does not affect this argument. if man has existed only six or seven thousand years, still at the beginning of his existence he was as distinct from lower animals as he is now, and shows no signs of gradation into other forms. if he has really endured since the great glacial period, and is to be regarded as a species of a hundred thousand years' continuance, still the fact is the same, and is, if possible, less favourable to derivation. similar facts meet us in other directions. i have for many years occupied a little of my leisure in collecting the numerous species of molluscs and other marine animals existing in a sub-fossil state in the post-pliocene clays of canada, and comparing them with their modern successors. i do not know how long these animals have lived. some of them certainly go far back into the tertiary; and recent computations would place even the glacial age at a distance from us of more then a thousand centuries. yet after carefully studying about two hundred species, and, of some of these, many hundreds of specimens, i have arrived at the conclusion that they are absolutely unchanged. some of them, it is true, are variable shells, presenting as many and great varieties as the human race itself; yet i find that in the post-pliocene even the varieties of each species were the same as now, though the great changes of temperature and elevation which have occurred, have removed many of them to distant places, and have made them become locally extinct in regions over which they once spread. here again we have an absolute refusal, on the part of all these animals, to admit that they are derived, or have tended to sport into new species. this is also, it is to be observed, altogether independent of that imperfection of the geological record of which so much is made; since we have abundance of these shells in the post-pliocene beds, and in the modern seas, and no one doubts their continued descent. to what does this point? evidently to the conclusion that all these species show no indication of derivation, or tendency to improve, but move back in parallel lines to some unknown creative origin. if it be objected to this conclusion that absence of derivation in the post-pliocene and modern does not prove that it may not previously have occurred, the answer is, that if the evolutionist admits that for a very long period (and this the only one of which we have any certain knowledge, and the only one which concerns man) derivation has been suspended, he in effect abandons his position. it may, however, be objected that what i have above affirmed of species may be affirmed of varieties, which are admitted to be derived. for example, it may be said that the negro variety of man has existed unchanged from the earliest historic times. it is carious that those who so often urge this argument as an evidence of the great antiquity of man, and the slow development of races, do not see that it proves too much. if the negro has been the same identical negro as far back as we can trace him, then his origin must have been independent, and of the nature of a creation, or else his duration as a negro must have been indefinite. what it does prove is a fact equally obvious from the study of post-pliocene molluscs and other fossils, namely, that new species tend rapidly to vary to the utmost extent of their possible limits, and then to remain stationary for an indefinite time. whether this results from an innate yet limited power of expansion in the species, or from the relations between it and external influences, it is a fact inconsistent with the gradual evolution of new species. hence we conclude that the recent origin of man, as revealed by geology, is, in connection with the above facts, an absolute bar to the doctrine of derivation. a second datum furnished to this discussion by geology and zoology is the negative one that no link of connection is known between man and any preceding animal. if we gather his bones and his implements from the ancient gravel-beds and cave-earths, we do not find them associated with any creature near of kin, nor do we find any such creature in those rich tertiary beds which have yielded so great harvests of mammalian bones. in the modern world we find nothing nearer to him then such anthropoid apes as the orangs and gorillas. but the apes, however nearly allied, cannot be the ancestors of man. if at all related to him by descent, they are his brethren or cousins, not his parents; for they must, on the evolutionist hypothesis, be themselves the terminal ends of distinct lines of derivation from previous forms. this difficulty is not removed by an appeal to the imperfection of the geological record. so many animals contemporary with man are known, both at the beginning of his geological history and in the present world, that it would be more then marvellous if no very near relative had ere this time been discovered at one extreme or the other, or at some portion of the intervening ages. further, all the animals contemporary with man in the post-glacial period, so far as is known, are in the same case. discoveries of this kind may, however, still be made, and we may give the evolutionist the benefit of the possibility. we may affirm, however, that in order to gain a substratum of fact for his doctrine, he must find somewhere in the later tertiary period animals much nearer to man then are the present anthropoid apes. this demand i make advisedly--first, because the animals in question must precede man in geological time; and secondly, because the apes, even if they preceded man, instead of being contemporary with him, are not near enough to fulfil the required conditions. what is the actual fact with regard to these animals, so confidently affirmed to resemble some not very remote ancestors of ours? zoologically they are not varieties of the same species with man they are not species of the same genus, nor do they belong to genera of the same family, or even to families of the same order. these animals are at least ordinally distinct from us in those grades of groups in which naturalists arrange animals. i am well aware that an attempt has been made to group man, apes, and lemurs in one order of "primates," and thus to reduce their difference to the grade of the family; but as pat by its latest and perhaps most able advocate, the attempt is a decided failure. one has only to read the concluding chapter of huxley's new book on the anatomy of the vertebrates to be persuaded of this, more especially if we can take into consideration, in addition to the many differences indicated, others which exist but are not mentioned by the author. ordinal distinctions among animals are mainly dependent on grade or rank, and are not to be broken down by obscure resemblances of internal anatomy, having no relation to this point, but to physiological features of very secondary importance. man must, on all grounds, rank much higher above the apes then they can do above any other order of mammals. even if we refuse to recognise all higher grounds of classification, and condescend, with some great zoologists of our time, to regard nature with the eyes of mere anatomists, or in the same way that a brick-layer's apprentice may be supposed to regard distinctions of architectural styles, we can arrive at no other conclusion. let us imagine an anatomist, himself neither a man nor a monkey, but a being of some other grade, and altogether ignorant of the higher ends and powers of our species, to contemplate merely the skeleton of a man and that of an ape. he must necessarily deduce therefrom an ordinal distinction, even on the one ground of the correlations and modifications of structure implied in the erect position. it would indeed be sufficient for this purpose to consider merely the balancing of the skull on the neck, or the structure of the foot, and the consequences fairly deducible from either of them. nay, were such imaginary anatomist a derivationist, and ignorant of the geological date of his specimens, and as careless of the differences in respect to brain as some of his human _confrères_, he might, referring to the loss specialised condition of man's teeth and foot, conclude, not that man is an improved ape, but that the ape is a specialised and improved man. he would be obliged, however, even on this hypothesis, to admit that there must be a host of missing links. nor would these be supplied by the study of the living races of men, because these want even specific distinctness, and differ from the apes essentially in those points on which an ordinal distinction can be fairly based. this isolated position of man throughout the whole period of his history, grows in importance the more that it is studied, and can scarcely be the result of any accident of defective preservation of intermediate forms. in the meantime, when taken in connection with, the fact previously stated, that man is equally isolated when he first appears on the stage, it deprives evolution, as applied to our species, of any precise scientific basis, whether zoological or geological. i do not attach any importance whatever, in this connection, to the likeness in type or plan between man and other mammals. evolutionists are in the habit of taking for granted that this implies derivation, and of reasoning as if the fact that the human skeleton is constructed on the same principles as that of an ape or a dog, must have some connection with a common ancestry of these animals. this is, however, as is usual with them, begging the question. creation, as well as evolution, admits of similarity of plan. when stephenson constructed a locomotive, he availed himself of the principles and of many of the contrivances of previous engines; but this does not imply that he took a mine-engine, or a marine-engine, and converted it into a railroad-engine. type or plan, whether in nature or art, may imply merely a mental evolution of ideas in the maker, not a derivation of one object from another. but while man is related in his type of structure to the higher animals, his contemporaries, it is undeniable that there are certain points in which he constitutes a new type; and if this consideration were properly weighed, i believe it would induce zoologists, notwithstanding the proverbial humility of the true man of science, to consider themselves much more widely separated from the brutes then even by the ordinal distinction above referred to. i would state this view of the matter thus:--it is in the lower animals a law that the bodily frame is provided with all necessary means of defence and attack, and with all necessary protection against external influences and assailants. in a very few cases, we have partial exceptions to this. a hermit-crab, for instance, has the hinder part of its body unprotected; and has, instead of armour, the instinct of using the cast-off shells of molluscs; yet even this animal has the usual strong claws of a crustacean, for defence in front. there are only a very few animals in which instinct thus takes the place of physical contrivances for defence or attack, and in these we find merely the usual unvarying instincts of the irrational animal. but in man, that which is the rare exception in all other animals, becomes the rule. he has no means of escape from danger, compared with those enjoyed by other animals no defensive armour, no natural protection from cold or heat, no effective weapons for attacking other animals. these disabilities would make him the most helpless of creatures, especially when taken in connection with his slow growth and long immaturity. his safety and his dominion over other animals, are secured by entirely new means, constituting a "new departure" in creation. contrivance and inventive power, enabling him to utilise the objects and forces of nature, replace in him the material powers bestowed on lower animals. obviously the structure of the human being is related to this, and so related to it as to place man in a different category altogether from any other animal. this consideration makes the derivation of man from brutes difficult to imagine. none of these latter appear even able to conceive or understand the modes of life and action of man. they do not need to attempt to emulate his powers, for they are themselves provided for in a different manner. they have no progressive nature like that of man. their relations to things without are altogether limited to their structures and instincts. man's relations are limited only by his powers of knowing and understanding. how then is it possible to conceive of an animal which is, so to speak, a mere living machine, parting with the physical contrivances necessary to its existence, and assuming the new role of intelligence and free action? this becomes still more striking if we adopt the view usually taken by evolutionists, that primitive man was a ferocious and carnivorous creature, warring with and overcoming the powerful animals of the post-glacial period, and contending with the rigours of a severe climate. this could certainly not be inferred from his structure, interpreted by that of the lower animals, which would inevitably lead to the conclusion that he must lave been a harmless and frugivorous creature, fitted to subsist only in the mildest climates, and where exempt from the attacks of the more powerful carnivorous animals. no one reasoning on the purely physical constitution of man, could infer that he might be a creature more powerful and ferocious then the lion or the tiger. it is also worthy of mention that the existence of primitive man as a savage hunter is, in another point of view, absolutely opposed to the darwinian idea of his origin from a frugivorous ape. these creatures, while comparatively inoffensive, conform to the general law of lower animals in having strong jaws and powerful canines for defence, hand-like feet to aid them in securing food, and escaping from their enemies, and hairy clothing to protect them from cold and heat. on the hypothesis of evolution we might conceive that if these creatures were placed in some eden of genial warmth, peace, and plenty, which rendered those appliances unnecessary, they might gradually lose these now valuable structures, from want of necessity, to use them. but, on the contrary, if such creatures were obliged to contend against powerful enemies, and to feed on flesh, all analogy would lead us to believe that they would become in their structures more like carnivorous beasts then men. on the other hand, the anthropoid apes, in the circumstances in which we find them, are not only as unprogressive as other animals, but little fitted to extend their range, and less gifted with the power of adapting themselves to new conditions then many other mammals less resembling man in external form. on the darwinian theory, such primitive men as geology reveals to us would be more likely to have originated from bears then apes, and we would be tempted to wish that man should become extinct, and that the chance should be given to the mild chimpanzee or orang to produce by natural selection an improved and less ferocious humanity for the future. the only rational hypothesis of human origin in the present state of our knowledge of this subject is, that man must have been produced under some circumstances in which animal food was not necessary to him, in which he was exempt from the attacks of the more formidable animals, and in less need of protection from the inclemency of the weather then is the case with any modern apes; and that his life as a hunter and warrior began after he had by his knowledge and skill secured to himself the means of subduing nature by force and cunning. this implies that man was from the first a rational being, capable of understanding nature, and it accords much more nearly with the old story of eden in the book of genesis, then with any modern theories of evolution. it is due to mr. wallace--who, next to darwin, has been a leader among english derivationists--to state that he perceives this difficulty. as a believer in natural selection, however, it presents itself to his mind in a peculiar form. he perceives that so soon as, by the process of evolution, man became a rational creature, and acquired his social sympathies, physical evolution must cease, and must be replaced by invention, contrivance, and social organisation. this is at once obvious and undeniable, and it follows that the natural selection applicable to man, as man, must relate purely to his mental and moral improvement. wallace, however, fails to comprehend the full significance of this feature of the case. given, a man destitute of clothing, he may never acquire such clothing by natural selection, because he will provide an artificial substitute. he will evolve not into a hairy animal, but into a weaver and a tailor. given, a man destitute of claws and fangs, he will not acquire these, but will manufacture weapons. but then, on the hypothesis of derivation, this is not what is given us as the raw material of man, but instead of this a hairy ape. admitting the power of natural selection, we might understand how this ape could become more hairy, or acquire more formidable weapons, as it became more exposed to cold, or more under the necessity of using animal food; but that it should of itself leave this natural line of development and enter on the entirely different line of mental progress is not conceivable, except as a result of creative intervention. absolute materialists may make light of this difficulty, and may hold that this would imply merely a change of brain; but even if we admit this, they fail to show of what use such better brain would be to a creature retaining the bodily form and instincts of the ape, or how such better brain could be acquired. but evolutionists are not necessarily absolute materialists, and darwin himself labours to show that the reasoning self-conscious mind, and even the moral sentiments of man, might be evolved from rudiments of such powers, perceptible in the lower animals. here, however, he leaves the court of natural science, properly so called, and summons us to appear before the judgment-seat of philosophy; and as naturalists are often bad mental philosophers, and philosophers have often small knowledge of nature, some advantage results, in the first instance, to the doubtful cause of evolution. since, however, mental science makes much more of the distinctions between the mind of man and the instinct of animals then naturalists, accustomed to deal merely with the external organism, can be expected to do, the derivationist, when his plea is fairly understood, is quite as certain to lose his cause as when tried by geology and zoology. he might indeed be left to be dealt with by mental science on its own ground; and as our province is to look at the matter from the standpoint of natural history, we might here close our inquiry. it may, however, be proper to give some slight notion of the width of the gulf to be passed when we suppose the mechanical, unconscious, repetitive nature of the animal to pass over into the condition of an intellectual and moral being. if we take, as the most favourable case for the evolutionist, the most sagacious of the lower animals--the dog,--for example and compare it with the least elevated condition of the human mind, as observed in the child or the savage, we shall find that even here there is something more then that "immense difference in degree" which darwin himself admits. making every allowance for similarities in external sense, in certain instinctive powers and appetites; and even in the power of comparison, and in certain passions and affections; and admitting, though we cannot be quite certain of this, that in these man differs from animals only in degree; there remain other and more important differences, amounting to the possession, on the part of man, of powers not existing at all in animals. of this kind are--first, the faculty of reaching abstract and general truth, ind consequently of reasoning, in the proper sense of the term; secondly, in connection with this, the power of indefinite increase in knowledge, and in deductions therefrom leading to practical results; thirdly, the power of expressing thought in speech; fourthly, the power of arriving at ideas of right and wrong, and thus becoming a responsible and free agent. lastly, we have the conception of higher spiritual intelligence, of supreme power and divinity, and the consequent feeling of religious obligation. these powers are evidently different in kind, rather then in degree, from those of the brute, and cannot be conceived to have arisen from the latter, more especially as one of the distinctive characters of these is their purely cyclical, repetitive, and unprogressive nature. sir john lubbock has, by a great accumulation of facts, or supposed facts, bearing on the low mental condition of savages, endeavoured to bridge over this chasm. it is obvious, however, from his own data, that the rudest savages are enabled to subsist only by the exercise of intellectual gifts far higher then those of animals; and that if these gifts were removed from them, they would inevitably perish. it is equally clear that even the lowest savages are moral agents; and that not merely in their religious beliefs and conceptions of good and evil, but also in their moral degradation, they show capacities not possessed by the brutes. it is also true that most of these savages are quite as little likely to be specimens of primitive man as are the higher races; and that many of them have fallen to so low a level as to be scarcely capable, of themselves, of rising to a condition of culture and civilisation. thus they are more likely to be degraded races, in "the eddy and backwater of humanity" then examples of the sources from whence it flowed. and here it must not be lost sight of, that a being like man has capacities for degradation commensurate with his capacities for improvement; and that at any point of his history we may have to seek the analogues of primeval man, rather in the average, then the extremes of the race. before leaving this subject, it may be well to consider the fact, that the occurrence of such a being as man in the last stages of the world's history is, in itself, an argument for the existence of a supreme creator. man is himself an image and likeness of god; and the fact that he can establish relations with nature around him, so as to understand and control its powers, implies either that he has been evolved as a soul of nature, by its own blind development, or that he has originated in the action of a higher being related to man. the former supposition has been above shown to be altogether improbable; so that we are necessarily thrown back upon the latter. we must thus regard man himself as the highest known work of a spiritual creator, and must infer that he rightly uses his reason when he infers from nature the power and divinity of god. the last point that i think necessary to bring forward here, is the information which geology gives as to the locality of the introduction of man. there can be no hesitation in affirming that to the temperate regions of the old continent belongs the honour of being the cradle of humanity. in these regions are the oldest historical monuments of our race; here geology finds the most ancient remains of human beings; here also seems to be the birthplace of the fauna and flora most useful and congenial to man; and here he attains to his highest pitch of mental and physical development. this, it is true, by no means accords with the methods of the derivationists. on their theory we should search for the origin of man rather in those regions where he is most depauperated and degraded, and where his struggles for existence are most severe. but it is surely absurd to affirm of any species of animal or plant that it must have originated at the limits of its range, where it can scarcely exist at all. on the contrary, common sense as well as science requires us to believe that species must have originated in those central parts of their distribution where they enjoy the most favourable circumstances, and must have extended themselves thence as far as external conditions would permit. one of the most wretched varieties of the human race, and as near as any to the brutes, is that which inhabits tierra del fuego, a country which scarcely affords any of the means for the comfortable sustenance of man. would it not be absolutely impossible that man should have originated in such a country? is it not certain, en the contrary, that the fuegian is merely a degraded variety of the aboriginal american race? precisely the same argument applies to the austral negro and the hottentot. they are all naturally the most aberrant varieties of man, as being at the extreme range of his possible extension, and placed in conditions unfavourable, either because of unsuitable climatal or organic associations. it is true that the regions most favourable to the anthropoid apes, and in which they may be presumed to have originated, are by no means the most favourable to man; but this only makes it the less likely that man could have been derived from such a parentage. while, therefore, the geological date of the appearance of man, the want of any link of connection between him and any preceding animal, and his dissimilar bodily and mental constitution from any creatures contemporary with him, render his derivation from apes or other inferior animals in the highest degree improbable, the locality of his probable origin confirms this conclusion in the strongest manner. it also shows that man and the higher apes are not likely to have originated in the same regions, or under the same conditions, and that the conditions of human origin are rather the coincidence of suitable climatal and organic surroundings then the occurrence of animals closely related in structure to man. changes of conditions in geological time will not meet this difficulty. they might lead to migrations, as they have done in the case of both plants and animals, but not to anything further. the hyena, whose bones are found in the english caves, has been driven by geological changes to south africa, but he is still the same hyena. the reindeer which once roamed in france is still the reindeer in lapland; and though under different geological conditions we might imagine the creature to have originated in the south of europe, a country not now suitable to it, this would neither give reason to believe that any animal now living in the south of europe was its progenitor, nor to doubt that it still remains unchanged in its new habitat. indeed, the absence of anything more then merely varietal change in man and his companion-animals, in consequence of the geological changes and migrations of the modern period, furnishes, as already stated, a strong if not conclusive argument against derivation; which here, as elsewhere, only increases our actual difficulties, while professing to extricate us from them. * * * * * the arguments in the preceding pages cover only a small portion of the extensive field opened up by this subject. they relate, however, to some of the prominent and important points, and i trust are sufficient to show that, as applied to man, the theory of derivation merely trifles with the great question of his origin, without approaching to its solution. i may now, in conclusion, sketch the leading features of primitive man, as he appears to us through the mist of the intervening ages, and compare the picture with that presented by the oldest historical records of our race. two pictures of primeval man are in our time before the world. one represents him as the pure and happy inhabitant of an eden, free from all the ills that have afflicted his descendants, and revelling in the bliss of a golden age. this is the representation of holy scripture, and it is also the dream of all the poetry and myth of the earlier ages of the world. it is a beautiful picture, whether we regard it as founded on historical fact, or derived from god himself, or from the yearnings of the higher spiritual nature of man. the other picture is a joint product of modern philosophy and of antiquarian research. it presents to us a coarse and filthy savage, repulsive in feature, gross in habits, warring with his fellow-savages, and warring yet more remorselessly with every living thing he could destroy, tearing half-cooked flesh, and cracking marrow-bones with stone hammers, sheltering himself in damp and smoky caves, with no eye heavenward, and with only the first rude beginnings of the most important arts of life. both pictures may contain elements of truth, for man is a many-sided monster, made up of things apparently incongruous, and presenting here and there features out of which either picture may be composed. evolutionists, and especially those who believe in the struggle for existence and natural selection, ignore altogether the evidence of the golden age of humanity, and refer us to the rudest of modern savages as the types of primitive man. those who believe in a divine origin for our race, perhaps dwell too much on the higher spiritual features of the edenic state, to the exclusion of its more practical aspects, and its relations to the condition of the more barbarous races. let us examine more closely both representations; and first, that of creation. the glacial period, with its snows and ice, had passed away, and the world rejoiced in a spring-time of renewed verdure and beauty. many great and formidable beasts of the tertiary time had disappeared in the revolutions which had occurred, and the existing fauna of the northern hemisphere had been established on the land. then it was that man was introduced by an act of creative power. in the preceding changes a region of western asia had been prepared for his residence. it was a table-land at the head waters of the rivers that flow into the euxine, the caspian, and the persian gulf. its climate was healthy and bracing, with enough of variety to secure vigour, and not so inclement as to exact any artificial provision for clothing or shelter. its flora afforded abundance of edible fruits, and was rich in all the more beautiful forms of plant life; while its clear streams, alluvial soil, and undulating surface, afforded every variety of station and all that is beautiful in scenery. it was not infested with the more powerful and predacious quadrupeds, and its geographical relations were such as to render this exemption permanent. in this paradise man found ample supplies of wholesome and nutritious food. his requirements as to shelter were met by the leafy bowers he could weave. the streams of eden afforded gold which he could fashion for use and ornament, pearly shells for vessels, and agate for his few and simple cutting instruments. he required no clothing, and knew of no use for it. his body was the perfection and archetype of the vertebrate form, full of grace, vigour, and agility. his hands enabled him to avail himself of all the products of nature for use and pleasure, and to modify and adapt them according to his inclination. his intelligence, along with his manual powers, allowed him to ascertain the properties of things, to plan, invent, and apply in a manner impossible to any other creature. his gift of speech enabled him to imitate and reduce to systematic language the sounds of nature, and to connect them with the thoughts arising in his own mind, and thus to express their relations and significance. above all, his maker had breathed into him a spiritual nature akin to his own, whereby he became different from all other animals, and the very shadow and likeness of god; capable of rising to abstractions and general conceptions of truth and goodness, and of holding communion with his creator. this was man edenic, the man of the golden age, as sketched in the two short narratives of the earlier part of genesis, which not only conform to the general traditions of our race on the subject, but bear to any naturalist who will read them in their original dress, internal evidence of being contemporary, or very nearly so, with the state of things to which they relate. "and god said, 'let us make man in our image, after our likeness; and let them rule over the fish of the sea, and over the birds of the air, and over the herbivora, and over all the land.' and god blessed them, and said unto them, 'be fruitful and multiply, and fill the earth and subdue it.' "and the lord god formed the man of the dust of the ground, and breathed into his nostrils the breath of life, and man became a living being. and the lord god planted a garden, eastward in eden, and there he placed the man whom he had formed. and out of the ground made the lord god to grow every tree that is pleasant to the sight and good for food. and a river went out of eden to water the garden, and parted from thence, becoming four heads (of great rivers). the name of the first is pison, compassing the whole land of chavila, where there is gold, and the gold of that land is good; there is (also) pearl and agate.... and the lord god took the man, and put him into the garden of eden, to cultivate it and to take care of it." before leaving this most ancient and most beautiful history, we may say that it implies several things of much importance to our conceptions of primeval man. it implies a centre of creation for man, and a group of companion animals and plants, and an intention to dispense in his case with any struggle for existence. it implies, also, that man was not to be a lazy savage, but a care-taker and utiliser, by his mind and his bodily labour, of the things given to him; and it also implies an intelligent submission on his part to his maker, and spiritual appreciation of his plans and intentions. it further implies that man was, in process of time, from eden, to colonise the earth, and subdue its wildness, so as to extend the conditions of eden widely over its surface. lastly, a part of the record not quoted above, but necessary to the consistency of the story, implies that, in virtue of his spiritual nature, and on certain conditions, man, though in bodily frame of the earth earthy, like the other animals, was to be exempted from the common law of mortality which had all along prevailed, and which continued to prevail, even among the animals of eden. further, if man fell from this condition into that of the savage of the age of stone, it must have been by the obscuration of his spiritual nature under that which is merely animal; in other words, by his ceasing to be spiritual and in communion with god, and becoming practically a sensual materialist. that this actually happened is asserted by the scriptural story, but its details would take us too far from our present subject. let us now turn to the other picture--that presented by the theory of struggle for existence and derivation from lower animals. it introduces us first to an ape, akin perhaps to the modern orang or gorilla, but unknown to us as yet by any actual remains. this creature, after living for an indefinite time in the rich forests of the miocene and earlier pliocene periods, was at length subjected to the gradually increasing rigours of the glacial age. its vegetable food and its leafy shelter failed it, and it learned to nestle among such litter as it could collect in dens and caves, and to seize and devour such weaker animals as it could overtake and master. at the same time, its lower extremities, no longer used for climbing trees, but for walking on the ground, gained in strength and size; its arms diminished; and its development to maturity being delayed by the intensity of the struggle for existence, its brain enlarged, it became more cunning and sagacious, and even learned to use weapons of wood or stone to destroy its victims. so it gradually grew into a fierce and terrible creature, "neither beast nor human," combining the habits of a bear and the agility of a monkey with some glimmerings of the cunning and resources of a savage. when the glacial period passed away, our nameless simian man, or manlike ape, might naturally be supposed to revert to its original condition, and to establish itself as of old in the new forests of the modern period. for some unknown reason, however, perhaps because it had gone too far in the path of improvement to be able to turn back, this reversion did not take place. on the contrary, the ameliorated circumstances and wider range of the new continents enabled it still further to improve. ease and abundance perfected what struggle and privation had begun; it added to the rude arts of the glacial time; it parted with the shaggy hair now unnecessary; its features became softer; and it returned in part to vegetable food. language sprang up from the attempt to articulate natural sounds. fire-making was invented and new arts arose. at length the spiritual nature, potentially present in the creature, was awakened by some access of fear, or some grand and terrible physical phenomenon; the idea of a higher intelligence was struck out, and the descendant of apes became a superstitious and idolatrous savage. how much trouble and discussion would have been saved, had he been aware of his humble origin, and never entertained the vain imagination that he was a child of god, rather then a mere product of physical evolution! it is, indeed, curious, that at this point evolutionism, like theism, has its "fall of man;" for surely the awakening of the religious sense, and of the knowledge of good and evil, must on that theory be so designated, since it subverted in the case of man the previous regular operation of natural selection, and introduced all that debasing superstition, priestly domination, and religious controversy which have been among the chief curses of our race, and which are doubly accursed if, as the evolutionist believes, they are not the ruins of something nobler and holier, but the mere gratuitous, vain, and useless imaginings of a creature who should have been content to eat and drink and die, without hope or fear, like the brutes from which he sprang. these are at present our alternative sketches: the genesis of theism, and the genesis of evolution. after the argument in previous pages, it is unnecessary here to discuss their relative degrees of probability. if we believe in a personal spiritual creator, the first becomes easy and natural, as it is also that which best accords with history and tradition. if, on the contrary, we reject all these, and accept as natural laws the postulates of the evolutionists which we have already discussed, we may become believers in the latter. the only remaining point is to inquire as to which explains best the actual facts of humanity as we find them. this is a view of which much has been made by evolutionists, and it therefore merits consideration. but it is too extensive to be fully treated of here, and i must content myself with a few illustrations of the failure of the theory of derivation to explain some of the most important features presented by even the ruder races of men. one of these is the belief in a future state of existence beyond this life. this belongs purely to the spiritual nature of man. it is not taught by physical nature, yet its existence is probably universal, and it lies near the foundation of all religious beliefs. lartet has described to us the sepulchral cave of aurignac, in which human skeletons, believed to be of post-glacial date, were associated with remains of funeral feasts, and with indications of careful burial, and with provisions laid up for the use of the dead. lyell well remarks on this, "if we have here before us, at the northern base of the pyrenees, a sepulchral vault with skeletons of human beings, consigned by friends and relatives to their last resting-place if we have also at the portal of the tomb the relics of funeral feasts, and within it indications of viands destined for the use of the departed on their way to a land of spirits; while among the funeral gifts are weapons wherewith in other fields to chase the gigantic deer, the cave-lion, the cave bear, and woolly rhinoceros--we have at last succeeded in tracing back the sacred rites of burial, and more interesting still, a belief in a future state, to times long anterior to those of history and tradition. rude and superstitious as may have been the savage of that remote era, he still deserved, by cherishing hopes of a hereafter, the epithet of 'noble,' which dryden gave to what he seems to have pictured to himself as the primitive condition of our race."[bf] [bf] "antiquity of man," p. in like manner, in the vast american continent, all its long isolated and widely separated tribes, many of them in a state of lowest barbarism, and without any external ritual of religious worship, believed in happy hunting-grounds in the spirit-land beyond the grave, and the dead warrior was buried with his most useful weapons and precious ornaments. "bring here the last gifts; and with them the last lament be said. let all that pleased and yet may please, be buried with the dead" was no unmeaning funeral song, but involved the sacrifice of the most precious and prized objects, that the loved one might enter the new and untried state provided for its needs. even the babe, whose life is usually accounted of so small value by savage tribes, was buried by the careful mother with precious strings of wampum, that had cost more months of patient labour then the days of its short life, that it might purchase the fostering care of the inhabitants of that unknown yet surely believed-in region of immortality. this "--wish that of the living whole no life may fail beyond the grave, derives it not from what we have the likest god within the soul?" is it likely to have germinated in the brain of an ape? and if so, of what possible use would it be in the struggle of a merely physical existence? is it not rather the remnant of a better spiritual life--a remembrance of the tree of life that grew in the paradise of god, a link of connection of the spiritual nature in man with, a higher divine spirit above? life and immortality, it is true, were brought to light by jesus christ, but they existed as beliefs more or less obscure from the first, and formed the basis for good and evil of the religions of the world. around this idea were gathered multitudes of collateral beliefs and religious observances; feasts and festivals for the dead; worship of dead heroes and ancestors; priestly intercessions and sacrifices for the dead; costly rites of sepulture. vain and without foundation many of these have no doubt been, but they have formed a universal and costly testimony to an instinct of immortality, dimly glimmering even in the breast of the savage, and glowing with higher brightness in the soul of the christian, but separated by an impassable gulf from anything derivable from a brute ancestry. the theistic picture of primeval man is in harmony with the fact that men, as a whole, are, and always have been, believers in god. the evolutionist picture is not. if man had from the first not merely a physical and intellectual nature, but a spiritual nature as well, we can understand how he came into relation with god, and how through all his vagaries and corruptions he clings to this relation in one form or another; but evolution affords no link of connection of this kind. it holds god to be unknowable even to the cultivated intellect of philosophy, and perceives no use in ideas with relation to him which, according to it must necessarily be fallacious, it leaves the theistic notions of mankind without explanation, and it will not serve its purpose to assert that some few and exceptional families of men have no notion of a god. even admitting this, and it is at best very doubtful, it can form but a trifling exception to a general truth. it appears to me that this view of the case is very clearly put in the bible, and it is curiously illustrated by a recent critique of "mr. darwin's critics," by professor huxley in the _contemporary review_. mr. mivart, himself a derivationist, but differing in some points from darwin, had affirmed, in the spirit rather of a romish theologian then of a biblical student or philosopher, that "acts unaccompanied by mental acts of conscious will" are "absolutely destitute of the most incipient degree of goodness." huxley well replies, "it is to my understanding extremely hard to reconcile mr. mivart's dictum with that noble summary of the whole duty of man, 'thou shalt love the lord thy god with all thy heart, and with all thy soul, and with all thy strength; and thou shalt love thy neighbour as thyself.' according to mr. mivart's definition, the man who loves god and his neighbour, and, out of sheer love and affection for both, does all he can to please them, is nevertheless destitute of a particle of real goodness." huxley's reply deserves to be pondered by certain moralists and theologians whose doctrine savours of the leaven of the pharisees, but neither huxley nor his opponent see the higher truth that in the love of god we have a principle far nobler and more god-like and less animal then that of mere duty. man primeval, according to the doctrine of genesis, was, by simple love and communion with his god, placed in the position of a spiritual being, a member of a higher family then that of the animal. the "knowledge of good and evil" which he acquired later, and on which is based the law of conscious duty, was a less happy attainment, which placed him on a lower level then that of the unconscious love and goodness of primal innocence. no doubt man's sense of right and wrong is something above the attainment of animals, and which could never have sprung from them; but still more is this the case with his direct spiritual relation to god, which, whether it rises to the inspiration of the prophet or the piety of the christian, or sinks to the rude superstition of the savage, can be no part of the adam of the dust but only of the breath of life breathed into him from above. that man should love his fellow-man may not seem strange. certain social and gregarious and family instincts exist among the lower animals, and darwin very ably adduces these as akin to the similar affections of man; yet even in the law of love of our neighbour, as enforced by christ's teaching, it is easy to see that we have something beyond animal nature. but this becomes still more distinct in the love of god. man was the "shadow and likeness of god," says the old record in genesis--the shadow that clings to the substance and is inseparable from it, the likeness that represents it visibly to the eyes of men, and of the animals that man rules over. primeval man could "hear in the evening breeze the voice of god, walking to and fro in the garden." what mere animal ever had or could attain to such an experience? but if we turn from the edenic picture of man in harmony with heaven--"owning a father, when he owned a god"--to man as the slave of superstition; even in this terrible darkness of mistaken faith, of which it may be said, "fear mates her devils, and weak faith her gods, gods partial, changeful, passionate, unjust, whose attributes are rage, revenge, or lust," we see the ruins, at least, of that sublime love of god. the animal clings to its young with a natural affection, as great as that of a human mother for her child, but what animal ever thought of throwing its progeny into the ganges, or into the fires of moloch's altar, for the saving of its soul, or to obtain the favour or avoid the wrath of god? no less in the vagaries of fetichism, ritualism, and idolatry, and in the horrors of asceticism and human sacrifice, then in the edenic communion with and hearing of god, or in the joy of christian love, do we see, in however ruined or degraded condition, the higher spiritual nature of man. this point leads to another distinction which, when properly viewed, widens the gap between man and the animals, or at least destroys one of the frail bridges of the evolutionists. lubbock and others affect to believe that the lowest savages of the modern world must be nearest to the type of primeval man. i have already attempted to show the fallacy of this. i may add here that in so holding they overlook a fundamental distinction, well pointed out by the duke of argyll, between the capacity of acquiring knowledge and knowledge actually acquired, and between the possession of a higher rational nature and the exercise of that nature in the pursuit of mechanical arts. in other words, primeval man must not be held to have been "utterly barbarous" because he was ignorant of mining or navigation, or of sculpture and painting. he had in him the power to attain to these things, but so long as he was not under necessity to exercise it, his mind may have expended its powers in other and happier channels. as well might it be affirmed that a delicately nurtured lady is an "utter barbarian" because she cannot build her own house, or make her own shoes. no doubt in such work she would be far more helpless then the wife of the rudest savage, yet she is not on that account to be held as an inferior being, or nearer to the animals. our conception of an angelic nature implies the absence of all our social institutions and mechanical arts; but does this necessitate our regarding an angel as an "utter barbarian"? in short, the whole notion of civilisation held by lubbock and those who think with him, is not only low and degrading, but utterly and absurdly wrong; and of course it vitiates all their conceptions of primeval man as well as of man's future destiny. further, the theistic idea implies that man was, without exhausting toil, to regulate and control nature, to rule over the animals, to cultivate the earth, to extend himself over it and subdue it; and all this as compatible with moral innocence, and at the same time with high intellectual and spiritual activity. there is, however, a still nicer and more beautiful distinction involved in this, and included in the wonderful narrative in genesis, so simple yet so much more profound then our philosophies; and which crops out in the same discussion of the critics of darwin, to which i have already referred. a writer in the _quarterly review_ had attempted to distinguish human reason from the intelligence of animals, as involving self-consciousness and reflection in our sensations and perceptions. huxley objects to this, instancing the mental action of a greyhound when it sees and pursues a hare, as similar to that of the gamekeeper when he lets slip the hound.[bg] [bg] _contemporary review_, november, , p. . "as it is very necessary to keep up a clear distinction between these two processes, let the one be called neurosis and the other psychosis. when the gamekeeper was first trained to his work, every step in the process of neurosis was accompanied by a corresponding step in that of psychosis, or nearly so. he was conscious of seeing something, conscious of making sure it was a hare, conscious of desiring to catch it, and therefore to loose the greyhound at the right time, conscious of the acts by which he let the dog out of the leash. but with practice, though the various steps of the neurosis remain--for otherwise the impression on the retina would not result in the loosing of the dog--the great majority of the steps of the psychosis vanish, and the loosing of the dog follows unconsciously, or, as we say, without thinking about, upon the sight of the hare. no one will deny that the series of acts which originally intervened between the sensation and the letting go of the dog were, in the strictest sense, intellectual and rational operations. do they cease to be so when the man ceases to be conscious of them? that depends upon what is the essence and what the accident of these operations, which taken together constitute ratiocination. now, ratiocination is resolvable into predication, and predication consists in marking, in some way, the existence, the co-existence, the succession, the likeness and unlikeness, of things or their ideas. whatever does this, reasons; and if a machine produces the effects of reason, i see no more ground for denying to it the reasoning power because it is unconscious, then i see for refusing to mr. babbage's engine the title of a calculating machine on the same grounds." here we have in the first place, the fact that an action, in the first instance rational and complex, becomes by repetition simple and instinctive. does the man then sink to the level of the hound, or, what is more to the purpose, does this in the least approach to showing that the hound can rise to the level of the man? certainly not; for the man is the conscious planner and originator of a course of action in which the instincts of the brute are made to take part, and in which the readiness that he attains by habit only enables him to dispense with certain processes of thought which were absolutely necessary at first. the man and the beast co-operate, but they meet each other from entirely different planes; the former from that of the rational consideration of nature, the latter from that of the blind pursuit of a mere physical instinct. the one, to use mr. huxley's simile, is the conscious inventor of the calculating machine, the other is the machine itself, and, though the machine can calculate, this fact is the farthest possible from giving it the power of growing into or producing its own inventor. but moses, or the more ancient authority from whom he quotes in genesis, knew this better then either of these modern combatants. his special distinctive mark of the superiority of man is that he was to have dominion over the earth and its animal inhabitants; and he represents this dominion as inaugurated by man's examining and naming the animals of eden, and finding among them no "help meet" for him.[bh] man was to find in them helps, but helps under his control, and that not the control of brute force, but of higher skill and of thought and even of love--a control still seen in some degree in the relation of man to his faithful companion, the dog. these old words of genesis, simple though they are, place the rational superiority of man on a stable basis, and imply a distinction between him and the lower animals which cannot be shaken by the sophistries of the evolutionists. [bh] literally, "corresponding," or "similar," to him. the theistic picture further accords with the fact that the geological time immediately preceding man's appearance was a time of decadence of many of the grander forms of animal life, especially in that area of the old continent where man was to appear. whatever may be said of the imperfection of the geological record, there can be no question of the fact that the miocene and earlier pliocene were distinguished by the prevalence of grand and gigantic forms of mammalian life, some of which disappeared in or before the glacial period, while others failed after that period in the subsidence of the post-glacial, or in connection with its amelioration of climate. the modern animals are also, as explained above, a selection from the grander fauna of the post-glacial period. to speak for the moment in darwinian language, there was for the time an evident tendency to promote the survival of the fittest, not in mere physical development, but in intelligence and sagacity. a similar tendency existed even in the vegetable world, replacing the flora of american aspect which had existed in the pliocene, with the richer and more useful flora of europe and western asia. this not obscurely indicates the preparing of a place for man, and the removal out of his way of obstacles and hindrances. that these changes had a relation to the advent of man, neither theist nor evolutionist can doubt, and it may be that we shall some day find that this relation implies the existence of a creative law intelligible by us; but while we fail to perceive any link of direct causation between the changes in the lower world, and the introduction of our race, we cannot help seeing that correlation which implies a far-reaching plan, and an intelligent design. finally, the evolutionist picture wants some of the fairest lineaments of humanity, and cheats us with a semblance of man without the reality. shave and paint your ape as you may, clothe him and set him up upon his feet, still he fails greatly of the "human form divine;" and so it is with him morally and spiritually as well. we have seen that he wants the instinct of immortality, the love of god, the mental and spiritual power of exercising dominion over the earth. the very agency by which he is evolved is of itself subversive of all these higher properties. the struggle for existence is essentially selfish, and therefore degrading. even in the lower animals, it is a false assumption that its tendency is to elevate; for animals when driven to the utmost verge of struggle for life, become depauperated and degraded. the dog which spends its life in snarling contention with its fellow-curs for insufficient food, will not be a noble specimen of its race. god does not so treat his creatures. there is far more truth to nature in the doctrine which represents him as listening to the young ravens when they cry for food. but as applied to man, the theory of the struggle for existence and survival of the fittest, though the most popular phase of evolutionism at present, is nothing less then the basest and most horrible of superstitions. it makes man not merely carnal, but devilish. it takes his lowest appetites and propensities, and makes them his god and creator. his higher sentiments and aspirations, his self-denying philanthropy, his enthusiasm for the good and true, all the struggles and sufferings of heroes and martyrs, not to speak of that self-sacrifice which is the foundation of christianity, are in the view of the evolutionist mere loss and waste, failure in the struggle of life. what does he give us in exchange? an endless pedigree of bestial ancestors, without one gleam of high or holy tradition to enliven the procession; and for the future, the prospect that the poor mass of protoplasm which constitutes the sum of our being, and which is the sole gain of an indefinite struggle in the past, must soon be resolved again into inferior animals or dead matter. that men of thought and culture should advocate such a philosophy, argues either a strange mental hallucination, or that the higher spiritual nature has been wholly quenched within them. it is one of the saddest of many sad spectacles that our age presents. still these men deserve credit for their bold pursuit of truth, or what seems to them to be truth; and they are, after all, nobler sinners then those who would practically lower us to the level of beasts by their negation even of intellectual life, or who would reduce us to apes, by making us the mere performers of rites and ceremonies, as a substitute for religion, or who would advise us to hand over reason and conscience to the despotic authority of fallible men dressed in strange garbs, and called by sacred names. the world needs a philosophy and a christianity of more robust mould, which shall recognise, as the bible does, at once body and soul and spirit, at once the sovereignty of god and the liberty of man; and which shall bring out into practical operation the great truth that god is a spirit, and they that worship him must worship him in spirit and in truth. such a religion might walk in the sunlight of truth and free discussion, hand in hand with science, education, liberty, and material civilisation, and would speedily consign evolution to the tomb which has already received so many superstitions and false philosophies. index. a abbeville, peat of, . acadian group, . advent of man, . agassiz on synthetic types, . _ammonitidæ_, . amphibians of the coal period, . andrews on the post-pliocene, . _anthracosaurus_, . anticosti formation, . antiquity of man, . _archæocyathus_, . archebiosis, . _arenicolites_, . _asterolepis_, . b _baculites_, . bala limestone, . _baphetes_, . barrande on primordial, . bastian on lower forms of life, . _beatricea_, . belemnites, . bigsby on silurian fauna, ; on primordial life, . billings on archæocyathus, ; on feet of trilobites, . binney on stigmaria, . biology as a term, . boulder clay, . brachiopods, or lamp-shells, . breccia of caverns, . brown, mr. k., on stigmaria, . c _calamites_, , , . calcaire grossier, . cambrian age, ; name defined, . caradoc rocks, . carbonic acid in atmosphere, . carboniferous age, ; land snails of the, ; crustaceans of the, ; insects of the, ; corals of the, ; plants of the, ; fishes of the, ; footprints in the, ; geography of the, ; reptiles of the, . carpenter on cretaceous sea, . carruthers on graptolites, . cave earth, . cavern deposits, . _cephalaspis_, . cephalopods of silurian, . _ceteosaurus_, ; foraminifera in the, . chalk, nature of, . chaos, . _climactichnites_, . coal, origin of, ; of the mesozoic, . colours of rocks, . continental plateaus, . continents, their origin, . _conulus prisons_, . cope on dinosaurs, ; on pterodactyl, ; on mososaurus, ; on caverns, . corals of the silurian, ; agency of, in forming limestone, , ; of the devonian, ; of the carboniferous, . corniferous limestone, . _coryphodon_, . creation, unity of, ; not by evolution, ; laws of, , ; statement of as a theory, ; requirements of, ; how treated by evolutionists, ; definition and explanation of, ; its probable conditions, . creator, evidence of a personal, , cretaceous period, , ; sea of the, . crinoids of the silurian, . croll on the post-pliocene, . _crusiana_, . crustaceans of the primordial, ; of the silurian, ; of the mesozoic, . crust of the earth, ; folding of, . cuvier on tertiary mammals, . cystideans, . d dana on geological periods, . darwin, nature of his theory, ; his account of the origin of man, ; his statement of descent of man, . davidson on brachiopods, . dawkins on post-glacial mammals, . delaunay on solidity of the earth, . deluge, the, . devonian, or brian age, ; physical condition of, ; tabular view of, ; corals of the, ; fishes of the, ; plants of the, ; geography of the, ; insects of the, . _dinichthys_, . dinosaurs, . _dromatherium_, . dudley, fossils of, . e earth, its earliest state, ; crust of the, ; folding of, ; gaseous state of, . edenic state of man, , . edwards, milne, on devonian corals, . _elasmosaurus_, . elephants, fossil, , . elevation and subsidence, , , , . enaliosaurs, . "engis" skull, its characters, . eocene seas, ; foraminifera of the, ; mammals of the, ; plants of the, ; footprints in the, . _eophyton_, . _eosaurus_, , eozoic period, . _eozoon bavaricum_, . _eozoon canadense_, , . erian, or devonian, ; reason of the name, ; table of erian formations, ; corals of the, ; fishes of the, ; plants of the, . eskers or kames, . etheridge on devonian, . _eurypterus_, , . evolution as applied to eozoon, ; primordial animals, ; silurian animals, ; trilobites, , ; reptiles, ; man, ; its character as a theory, ; its difficulties, ; its "fall of man," , f falconer on indian miocene, . _favosites_, . ferns of the devonian, ; of the carboniferous, . fishes, ganoid, ; of the silurian, ; of the devonian, ; of the carboniferous, . flora of the silurian, ; of the devonian, ; of the carboniferous, ; of the permian, ; of the mesozoic, ; of the eocene, ; of the miocene, . footprints in the carboniferous, ; in the trias, ; in the eocene, . foraminifera, nature of, ; laurentian, ; of the chalk, ; of the tertiary, . forbes on post-glacial land, . forests of the devonian, ; of the carboniferous, . g ganoid fishes, , . gaseous state of the earth, . genesis, book of, its account of chaos, ; of creation of land, ; of palæozoic animals, ; of creation of reptiles, ; of creation of mammals, , ; of the deluge, ; of creation of man, ; of eden, . genesis of the earth, . geography of the silurian, ; of the devonian, ; of the carboniferous, ; of the permian, . geological periods, , . glacial period, , . glauconite, . _glyptoerinus_, . graptolites, . greenland, miocene flora of, . greensand, . gümbel on bavarian eozoon, . h _hadrosaurus_, . hall on graptolites, ; harlech beds, . heer on tertiary plants, . helderberg rocks, . hercynian schists, . heterogenesis, . hicks on primordial fossils, . hilgard on mississippi delta, . hippopotamus, fossil, . _histioderma_, . hopkins on solidity of the earth, . hudson river group, . hull on geological periods, . hunt, dr. t. s., on volcanic action, ; on chemistry of primeval earth, ; on lingulæ, . huronian formation, . huxley on coal, ; on carboniferous reptiles, ; on dinosaurs, ; on paley's argument from design, ; on good and evil, ; on intuitive and rational actions, ; on tendency of evolutionist views, . _hylonomus_, . i ice-action in permian, ; in post-pliocene, . _ichthyosaurus_, . _iguanodon_, . insects, devonian, ; carboniferous, . intelligence of animals, nature of, . j jurassic, subdivisions of, . k kames, . kaup on dinotherium, . kent's cavern, . king-crabs of carboniferous, . king on carboniferous reptiles, . l _labyrinthodon_, , lælaps, . lamp-shells, . land-snails of carboniferous, . la place's nebular theory, . laurentian rocks, ; life in the, ; plants of the, . _lepidodendron_, , , . _leptophleum_, . limestone corniferous, ; nummulitic, ; milioline, ; silurian, ; origin of, , , . _limulus_, . _lingulæ_, . lingula flags, . logan, sir w., on laurentian rocks, ; on reptilian footprints, . london clay, . longmynd rocks, , . lower helderberg group, . ludlow group, . lyell, sir c., on devonian limestone, ; on wealden, ; on classification of the tertiary, . m _machairodus_, . magnesian limestones, . mammals of the mesozoic, ; of the eocene, ; of the miocene, ; of the pliocene, ; of the post-glacial, . man, advent of, . man, antiquity of, ; history of, according to theory of creation, ; according to evolution, ; widely different from apes, ; a new type, ; primitive, not a savage, ; his spiritual nature, , , ; locality of his origin, ; primeval, according to creation, ; according to evolution, . mayhill sandstone, . medina sandstone, . _megalosaurus_, . menevian formation, . mesozoic ages, ; subdivisions of, ; flora of, ; coal of, ; crustaceans of the, ; reptiles of the, , . metalliferous rocks, . metamorphism, . _microlestes_, . milioline limestones, . miller on old bed sandstone, . millipedes, fossil, . miocene plants, ; climate, ; mammals of, . mississippi, delta of the, . modern period, . _mosasaurus_, . morse on lingula, . murchison on the silurian, . n nebular theory, . neolithic age, . neozoic ages, ; divisions of, . newberry on dinichthys, . nicholson on graptolites, , nummulitic limestones, . o _oldhamia_, . old bed sandstone, . oneida conglomerate. . _orthoceratites_, , . oscillations of continents, . owen on dinosaurs, ; on marsupials, . p palæolithic age, , . _palæophis_, . palæozoic life, ; diagram of, . paley on design in nature; his illustration of the watch, . peat of abbeville, . pengelly on kent's hole, . _pentremites_, . periods, geological, , . permian age, ; geography of the, ; ice-action in the, ; plants of the, ; reptiles of the, . phillips on dawn of life, ; on ceteosaurus, . pictet on post-pliocene mammals, ; on post-glacial animals, . pictures of primeval man, . pierce on diminution of earth's rotation, . pines of the devonian, ; of the carboniferous, ; of the permian, . placoid fishes, . plants of the laurentian, ; of the silurian, ; of the devonian, ; of the carboniferous, ; of the permian, ; of the mesozoic, ; of the tertiary ; classification of, . plateaus, continental, . _plesiosaurus_, . pliocene, climate of, ; mammals of, . _pliosaurus_, . pluvial period, . post-glacial age, , . post-pliocene period, ; cold, ; ice-action in the, ; subsidence, ; elevation, ; shells, evidence of, against derivation, ; mammals, evidence of, against derivation, . potsdam sandstone, . prestwich on st. acheul, . primordial age, ; crustacean of the, . _protichnites_, . _protorosaurus_, . _prototaxites_, . _psilophyton_, , . _pteraspis_, . _pterichthys_, . pterodactyls, . _pterygotus_, . _pupa vetusta_, . q quebec group, . r rain-marks, . ramsay on permian, . red sandstones, their origin, , . reptiles of the carboniferous, ; of the permian, ; of the mesozoic, , . rhinoceros, fossil, . rocks, colours of, . rotation of the earth, its gradual diminution, . s salter on fossil crustacea, . sedgwick on cambrian, , . seeley on pterodactyls, . shrinkage-cracks, . _sigillaria_, , . silurian ages, ; cephalopoda of the, ; corals of the, ; crinoids of the ; crustaceans of the, ; fishes of the, ; plants of the, . siluro-cambrian, use of the term, . slaty structure, . solidity of the earth, . somme, r., gravels of, . species, nature of the, ; how created, . spencer, his exposition of evolution, , . spiritual nature of man, , , . spore-cases in coals and shales, . stalagmite of caves, . striated rock-surfaces, . stumps, fossil of carboniferous, . synthetic types, . t table of devonian rocks, ; of palæozoic ages, ; of mesozoic ages, ; of neozoic ages, ; of post-pliocene, . temperature of interior of the earth, . tertiary period, ; mammals of, , , ; classification of its rocks, . thomson, sir w., on solidity of the earth, . time, geological divisions of, . tinière, cone of, . trenton limestone, , . trias, divisions of, ; footprints in the, . trilobites, , , ; feet of, . turtles of mesozoic, . tylor on pluvial period, . tyndall on carbonic acid in atmosphere, . u uniformitarianism in geology, . utica shale, . v volcanic action, ; of cambrian age, ; of silurian age, ; of devonian age, , . von dechen on reptiles of carboniferous, , . von meyer on dinosaurs, . w _walchia_, . wallace, his views on inapplicability of natural selection to man, . wealden, . wenlock group, . _williamsonia gigas_, . williamson on calamites, . woodward on pterygotus, . z zaphrentis . valuable and interesting works for public & private libraries, published by harper & brothers, new york. 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sheep, $ ; half calf, $ . reclus's earth. the earth: a descriptive history of the phenomena of the life of the globe. by Élisée reclus. with maps and illustrations, and page maps printed in colors. vo, cloth, $ . reclus's ocean. the ocean, atmosphere, and life. being the second series of a descriptive history of the life of the globe. by Élisée reclus. profusely illustrated with maps or figures, and maps printed in colors. vo, cloth, $ . griffis's japan. the mikado's empire: book i. history of japan, from b.c. to a.d. book ii. personal experiences, observations, and studies in japan, - . by william elliot griffis, a.m., late of the imperial university of tokio, japan. copiously illustrated. vo, cloth, $ ; half calf, $ . baker's ismailÏa. ismailïa: a narrative of the expedition to central africa for the suppression of the slave-trade, organized by ismail, khedive of egypt. by sir samuel white baker, pasha, f.r.s., f.r.g.s. with maps, portraits, and illustrations. vo, cloth, $ ; half calf, $ . smiles's history of the huguenots. the huguenots: their settlements, churches, and industries in england and ireland. by samuel smiles. with an appendix relating to the huguenots in america. crown vo, cloth, $ . smiles's huguenots after the revocation. the huguenots in france after the revocation of the edict of nantes; 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[in addition to the notes on chapter lxxvi., which correct the errors of the original work concerning the united states, a copious analytical index has been appended to this american edition.] second series: from the fall of napoleon, in , to the accession of louis napoleon, in . vols., vo, cloth, $ ; sheep, $ ; half calf, $ . samuel johnson: his words and his ways; what he said, what he did, and what men thought and spoke concerning him. edited by e. t. mason. mo, cloth, $ . johnson's complete works. the works of samuel johnson, ll.d. with an essay on his life and genius, by a. murphy. vols., vo, cloth, $ ; sheep, $ ; half calf, $ . schliemann's ilios. ilios, the city and country of the trojans. a narrative of the most recent discoveries and researches made on the plain of troy. with illustrations representing nearly types of the objects found in the excavations of the seven cities on the site of ilios. by dr. henry schliemann. maps, plans, and illustrations. imperial vo, illuminated cloth, $ . boswell's johnson. the life of samuel johnson, ll.d., including a journal of a tour to the hebrides. by james boswell. edited by j. w. croker, ll.d., f.k.s. with a portrait of boswell. vols., vo, cloth, $ ; sheep, $ ; half calf, $ . addison's complete works. the works of joseph addison, embracing the whole of the _spectator_. vols., vo, cloth, $ ; sheep, $ ; half calf, $ . bourne's locke. the life of john locke. by h. r. fox bourne. vols., vo, cloth, uncut edges and gilt tops, $ . english correspondence. four centuries of english letters. selections from the correspondence of one hundred and fifty writers from the period of the paston letters to the present day. edited by w. baptiste scoones. mo, cloth, $ . the student's series. maps and illustrations. mo, cloth. france.--gibbon.--greece.--rome (by liddell).--old testament history.--new testament history.--strickland's queens of england (abridged).--ancient history of the east.--hallam's middle ages.--hallam's constitutional history of england.--lyell's elements of geology.--merivale's general history of rome.--cox's general history of greece.--classical dictionary. $ per volume. lewis's history of germany.--ecclesiastical history.--hume's england. $ per volume. cameron's across africa. across africa. by verney lovett cameron. map and illustrations. vo, cloth, $ . bulwer's miscellaneous prose works. the miscellaneous prose works of lord lytton. vols., mo, cloth, $ . also, in uniform style, _caxtoniana_. mo, cloth, $ . carlyle's frederick the great. history of friedrich ii., called frederick the great. by thomas carlyle. portraits, maps, plans, etc. vols., mo, cloth, $ ; sheep, $ ; half calf, $ . carlyle's french revolution. the french revolution: a history. by thomas carlyle. vols., mo, cloth, $ ; sheep, $ ; half calf, $ . carlyle's oliver cromwell. oliver cromwell's letters and speeches, including the supplement to the first edition. with elucidations. by thomas carlyle. vols., mo, cloth, $ ; sheep, $ ; half calf, $ . abbott's history of the french revolution. the french revolution of , as viewed in the light of republican institutions. by john s. c. abbott. illustrated. vo, cloth, $ ; sheep, $ ; half calf, $ . abbott's napoleon. the history of napoleon bonaparte. by john s. c. abbott. maps, illustrations, and portraits. vols., vo, cloth, $ ; sheep, $ ; half calf, $ . abbott's napoleon at st. helena. napoleon at st. helena; or, anecdotes and conversations of the emperor during the years of his captivity. collected from the memorials of las casas, o'meara, montholon, antommarchi, and others. by j. s. c. abbott. illustrated. vo, cloth, $ ; sheep, $ ; half calf, $ . abbott's frederick the great. the history of frederick the second, called frederick the great. by john s. c. abbott. illustrated. vo, cloth, $ ; 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comprising full information on biblical, theological, and ecclesiastical subjects. with nearly maps and illustrations. edited by lyman abbott, with the co-operation of t. j. conant, d.d. royal vo, cloth, $ ; sheep, $ ; half morocco, $ . parton's caricature. caricature and other comic art, in all times and many lands. by james parton. illustrations. vo, cloth, uncut edges and gilt tops, $ ; half calf, $ . mahaffy's greek literature. a history of classical greek literature. by j. p. mahaffy. vols., mo, cloth, $ . du chaillu's equatorial africa. explorations and adventures in equatorial africa: with accounts of the manners and customs of the people, and of the chase of the gorilla, crocodile, leopard, elephant, hippopotamus, and other animals. by p. b. du chaillu. illustrated. vo, cloth, $ ; sheep, $ ; half calf, $ . du chaillu's ashango land. a journey to ashango land, and further penetration into equatorial africa. by p. b. du chaillu. illustrated. vo, cloth, $ ; sheep, $ ; half calf, $ . dexter's congregationalism. the congregationalism of the last three hundred years, as seen in its literature: with special reference to certain recondite, neglected, or disputed passages. with a bibliographical appendix. by h. m. dexter. large vo, cloth, $ . trollope's cicero. life of cicero. by anthony trollope. mo, cloth. bayne's lessons from my masters. lessons from my masters: carlyle, tennyson, and ruskin. by peter bayne, m.a., ll.d. mo, cloth, $ . stanley's through the dark continent. through the dark continent; 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half calf, $ . (in a box.) * * * * * transcriber's notes all obvious typographical errors were corrected. on page , there is an opening quote; but no closing one follows. based on the text ("returning from this digression...") on page , it was assumed that the closing quote should have been at the end of the preceding paragraph. hyphenation and accents were standardized. however, some hyphenated and separate word usage (for example, sea bottom(s) and sea-bottom(s)) were retained due to their grammatic usage. obtained from the internet archive. transcriber's note italicized text is displayed as _text_ and bold text as =text=. whole and fractional parts of numbers are displayed as - / . some utf- characters were converted to plain ascii. to view them, see the html or utf- version. department of the interior. john barton payne, secretary united states geological survey george otis smith, director the preparation of illustrations for reports of the united states geological survey with brief descriptions of processes of reproduction by john l. ridgway washington government printing office +==================================+ | | | the preparation of illustrations | | | | for reports of the | | | | united states geological survey | | | | | | by | | | | | | john l. ridgway | | | +==================================+ contents. part i. preparation by authors. page. introduction purpose and value of illustrations selection and approval of illustrations submittal of illustrations kinds of illustrations sizes of illustrations subdivisions of plates and figures preparation of copy by authors character of original material preliminary preparation of maps material available for base maps basic features of maps standard scales orientation of maps projection explanation titles of maps and other illustrations symbols used on maps general features letter symbols oil and gas symbols symbols for use on maps showing features of ground water black-line conventions materials used in preparing maps paper bristol board tracing linen inks drawing pens pencils rubber erasers and cleaners colored pencils and crayons water colors japanese transparent water colors coloring geologic maps diagrams essential features plans of mine workings sections lithologic symbols use of photographs as illustrations essential features copyrighted photographs sources of photographs lending original photographs and drawings unpublished photographs specimens general requirements borrowed and fragile specimens transmittal of paleontologic specimens making up plates reuse of illustrations approval of finished illustrations revision of illustrations submittal of proofs proof-reading illustrations general considerations part ii. preparation by draftsmen. general directions instruments classification of material preparation of maps projection details of base maps transferring or copying tracing celluloid transferring sketching by reticulation the "shadowless drafting table" topographic features relief hydrography cultural features lettering general directions lettering by type abbreviations names of railroads make-up of maps forms for certain features border title explanation graphic scales for maps symbols areal patterns for black and white maps standard colors for geologic maps reduction or enlargement of maps diagrams sections plans and cross sections of mines drawings of specimens of rocks and fossils methods used brush and pencil drawings pen drawings retouching photographs of specimens landscape drawings from poor photographs pen drawings made over photographs brush drawings from poor photographs outdoor sketches drawings of crystals retouching photographs part iii. processes of reproducing illustrations. methods employed photoengraving general features zinc etching copper etching in relief half-tone engraving three-color half-tone process wax engraving (the cerotype process) wood engraving photogelatin processes lithography original process photolithography offset printing chromolithography engraving on stone and on copper appendix. length of degrees of latitude and longitude metric system and equivalents geologic eras, periods, systems, epochs, and series chemical elements and symbols greek alphabet roman numerals mathematical signs names of rocks illustrations. page. plate i. methods of inserting plates and figures ii. symbols used on geologic maps, economic maps, and mine plans iii. lithologic symbols used in structure and columnar sections to represent different kinds of rock iv. symbols used on base maps v. reduction sheet used in lettering illustrations vi. half-tone prints showing effects produced by the use of six standard screens vii. details of the make-up of a geologic map viii. patterns used to show distinctions between areas on black and white maps ix. diagrams and curves figure . diagrams showing principal, guide, and auxiliary meridians, standard and special parallels and correction lines, and system of numbering townships, ranges, and sections . conventional lines used in preparing plans and diagrams of mine workings to distinguish different levels . section and perspective view showing relations of surface features to the different kinds of rocks and the structure of the beds . sections of coal beds . diagram illustrating method of projecting a map . methods of expressing relief by contour lines, by hachures, by shading on stipple board, and by a brush drawing . designs for bar scales . method of making a bar scale for a map of unknown scale . map bearing six areal line patterns . diagram showing method of marking maps for reduction or enlargement (for record) . structure section showing method of determining the succession of folds the preparation of illustrations for reports of the united states geological survey. by john l. ridgway. part i. preparation by authors. introduction. there has been an obvious need in the geological survey of a paper devoted wholly to illustrations. no complete paper on the character, use, and mode of preparation of illustrations has been published by the survey, though brief suggestions concerning certain features of their use have been printed in connection with other suggestions pertaining to publications. the present paper includes matter which it is hoped will be of service to authors in their work of making up original drafts of illustrations and to draftsmen who are using these originals in preparing more finished drawings, but it is not a technical treatise on drafting. the effectiveness of illustrations does not depend entirely on good drawings nor on good reproduction; it may be due in large part to the inherent character of the rough material submitted. if this material is effective or striking the finished illustrations, if well made, will be equally effective and striking. each step in the making of an illustration--first the preparation of the author's original or rough draft, next the final drawing, and last the reproduction--is closely related to the others, and each is dependent on the others for good results. if the material has been well handled at all three steps the resulting illustration should be above criticism; if it has been poorly handled at any one of the three the effectiveness of the illustration is either impaired or ruined. a consideration of processes of reproduction is essential in the preparation of all illustrations, and the influence or effect of the process to be selected on the methods of preparing a drawing has seemed to warrant the presentation of brief descriptions of the processes usually employed by the geological survey. these descriptions include statements as to the kind of copy that is suitable for each process, the result produced by each, and the relative cost of the processes. purpose and value of illustrations. an illustration in a report of the geological survey is not merely a picture having a remote bearing on the subject matter of the report; it must represent or explain something discussed or mentioned in order to become an illustration in the true sense of the term. the illustrations used in the survey's reports are not employed for embellishment; the more pictorial kinds may be in some measure decorative, but decoration is distinctly not their primary purpose. the illustrations used in popular literature are designed to meet a public demand for ornament or attractiveness. those used in scientific publications should be made plain and direct, without attempt to ornament or beautify. in the literature of science illustrations made by the reproduction of photographs or of explanatory diagrams or maps are intended simply to furnish greater illumination, and if the illustrations display photographic reality most statements or conclusions thus illuminated seem less open to dispute. a photograph may thus serve the double purpose of explanation and corroboration. the graphic expression of data and of details in a survey report is intended to aid the reader in comprehending the report, and this is the prime advantage of its use, but it also enables the writer to omit from his text numerous descriptive details. it would generally be difficult without illustrations to present a clear picture of the geology of a region in its exact relations, and especially to describe adequately the form and the details of the structure of many fossils. the tasks of both the writer and the reader of reports on geology and kindred subjects are thus greatly facilitated by geologic maps, sections, paleontologic drawings, and illustrations of other kinds. the responsibility for good and effective illustrations rests largely upon the author, who should select and plan his illustrations with a view to their utility in aiding the reader to understand his report. selection and approval of illustrations. there is no rule limiting the number of illustrations that may be used in a publication of the geological survey, but in selecting illustrations for a report an author may easily fall into the error of over-illustration. the number of diagrammatic drawings or of drawings that express the author's deductions is rarely in excess of the needs of a paper, but the number of photographs submitted is often excessive. the number of pages in a manuscript may be a factor in determining the proper number of illustrations, but as the need of illustrations varies greatly from paper to paper this factor alone is not decisive. the tendency to overillustrate led the director to issue the following order[ ] governing the approval of illustrations: [footnote : from survey order , oct. , .] the primary responsibility for the selection of illustrative material shall rest upon the author and the chief of the branch transmitting the report: no one knows the subject matter of the report better than its author, though a sympathetic critic is usually needed to correct the personal equation that may express itself in an excessive number of illustrations or the use of photographs into which no one but the field man himself can read what he wishes to illustrate. the approval by the chief of branch of the illustrations selected by the author will be taken as vouching for those illustrations as essential and adequate, and the scientific value of the illustrations will not be subject to review in the section of illustrations. the chief of the section of illustrations shall decide the technical questions relating to the preparation of these illustrations for reproduction and may recommend the rejection of any that do not promise effective or economical reproduction. in the consideration of such questions, especially any relating to maps, the cooperation of the editor of geologic maps and chief engraver will be expected. the judgment of an author as to the illustrative value of a photograph is likely to be biased by his knowledge of the features that are actually included in the view represented, not all of which may be shown clearly in the photograph; his knowledge of all the features enables him to see more in his picture than his readers will be able to recognize without detailed description. photographs in which special or significant features are obscured by foliage or lost in hazy distance do not make acceptable illustrations, and the use of a picture that requires much description to make it illustrate reverses, in a measure, the relations of text and illustrations. a photograph is not necessarily good for reproduction simply because it shows some particular feature to be illustrated; the quality of the print it will afford when reproduced from an engraved plate should also be considered. some loss of detail by reproduction must be expected, and therefore only the clearest and most effective prints obtainable should be submitted. if an author has difficulty in making his preliminary or "original" drawings he may request that a draftsman be detailed to aid him. the request should be made to the director through the chief of branch and properly approved. the work will then be done in the section of illustrations as advance preparation, but finished drawings should not be thus prepared unless the conditions are unusual. the administrative geologist reviews all illustrations submitted and represents the director in matters relating to illustrations. submittal of illustrations. all material intended for illustrations, except paleontologic specimens, should be submitted with the manuscript of the paper to be illustrated but in a separate package marked "illustrations to accompany a paper on ---- by ----." the package should contain a carbon copy of the list of illustrations that accompanies the manuscript or, if the titles to be printed on or with the illustrations include fuller descriptions than are given in that list, a carbon copy of the list giving complete titles and descriptions, the original of which should also accompany the manuscript. in the list each plate and figure should be separately numbered consecutively in the order in which it should appear in the report, and a figure opposite each title should show the number of the manuscript page on which the illustration is first mentioned or most fully discussed. roman numerals should be used for the plates and arabic numerals for the figures. each drawing or photograph should bear, in addition to the number and title, any suggestions concerning preparation, reduction, and method of reproduction which the author may consider especially desirable. the list should be headed "illustrations." specimens other than fossils that are to be illustrated must be submitted directly to the section of illustrations, but the author may first obtain photographic prints of them in order to make up his plates. the specimens should be carefully packed and any that are fragile should be so marked. kinds of illustrations. the illustrations in reports of the geological survey may be classified into five more or less distinct groups--( ) maps, ( ) diagrams (including graphs, sections, plans, figures of apparatus, and stereograms), ( ) outdoor photographs, ( ) photographs and drawings of specimens, and ( ) sketches. these may be further divided into two large groups, which may be called permanent and ephemeral. the permanent group includes illustrations that do not lose value through lapse of time or by natural alteration, such as detailed geologic maps, well-prepared structure sections, views of specimens, and good photographs or drawings of natural phenomena; the ephemeral group includes maps showing progress, key maps, diagrams showing yearly production, and many others that should be prepared in such a way as to minimize cost of preparation and reproduction. [illustration: u. s. geological survey preparation of illustrations plate i methods of inserting plates and figures. , , , , , , plates; , , , , figures; , pocket.] the illustrations will be finally divided into plates and figures when they are fully prepared, but if an author desires to determine the classification in advance of transmittal he should submit his material to the section of illustrations, where methods, processes, and reductions will be decided for each. in determining which shall be plates and which shall be figures, size and method of reproduction are the only factors to be considered; there are no other real differences. illustrations that require separate or special printing, such as those reproduced by lithography and by the photogravure, photogelatin, and three-color processes, must be printed separately from the text as plates and inserted in the report at the proper places; those that are reproduced by relief processes, such as zinc and copper etching and wax engraving, if not too large, can be printed with the text as figures. if an illustration to be reproduced by a relief process is marked for reduction to a size not exceeding that of the page of the text, it can be called a figure and be printed with the text. half tones, though etched in relief, are rarely made text figures in survey reports, because to give satisfactory impressions they must be printed on the best quality of coated paper, which is not used for the text. by using the coarser screens shown in plate vi (p. ), however, a half-tone cut may be made that can be used in the text if it is smaller than the page. sizes of illustrations. the regular book publications of the geological survey are issued in three sizes--( ) octavo (annual reports of the director, statistical reports on mineral resources, bulletins, and water-supply papers); ( ) quarto (professional papers and monographs); ( ) folio (geologic folios). the following table gives the measure of the text of each size and the measure of the trimmed page, in inches: size of text. size of page. octavo - / by - / - / by - / quarto - / by - / - / by - / folio - / by - / - / by - / most professional papers are printed in two columns of type, each inches wide, and folios are printed in three columns, each - / inches wide. a text figure in one of these publications can be made to fit one or more columns, and it may run the full length of the text page. the limits of the dimensions of plates and figures, in inches, are given in the following table. if for any reason a plate can not be reduced to the dimensions of a page it can be folded once or more; and if it is large and unwieldy it may be placed in a pocket on the inside of the back cover. (see pl. i.) single-page plate with plate. one side fold. text figure. octavo - / by - / - / by - / - / by - / quarto by - / by - / or by - / folio by - / ............ - / or - / by - / for an octavo report a single-page plate with side title should be inches or less in width, and a plate with bottom title should be inches or less in depth. in other words, the actual depth and width of a single-page plate in a page of any size must depend on the number of lines in its title, the inclusion of which should not extend the matter much, if any, beyond the dimensions given in the table. a difference of inch or less in the width of a folding plate may determine whether it must be folded once or twice, so that by consulting this table an author may save expense in binding and promote the reader's convenience in handling the plate. a text figure (including the title) can not extend beyond the text measure but may be of any size or shape within that measure, as shown on plate i, figures , , , . subdivisions of plates and figures. if a plate consists of two or more parts or photographs each part should be marked with an italic capital letter--=a=, =b=, etc.--which should be placed directly under each. if it is made up of many parts, in the form of plates that accompany reports on paleontology, each part should be similarly marked with an arable numeral-- , , , etc. if a text figure is subdivided into two or more parts, each part should be marked with a roman capital--a, b, c, etc.; and if details of a part are to be described each detail should be marked by an italic lower-case letter--a, , c, etc. preparation of copy by authors. character of original material. in the geological survey, as elsewhere, the "originals"--that is, the original material submitted by authors for the illustration of their reports--differ greatly in character and in degree of clearness. some are carefully prepared; others are rough, obscure in part, and defective in detail. drawings made from poor originals progress slowly, because the draftsman spends much time in interpreting uncertain features or in conference with the author concerning details. an original should be perfectly clear in detail and meaning, so that the draftsman can follow it without doubt. it should not consist of parts that must be brought together to make a new drawing, because the result of the combination of the parts will be uncertain at the outset and may not prove satisfactory. each original illustration should be prepared with the idea that the draftsman who will make the finished drawing will be unfamiliar with the subject and will need definite instructions; all data should be plotted and each figure or plate should be completely made up before it is submitted. more or less roughly prepared originals are expected, but they should show no uncertainty in details. obscure features may be cleared up by inclosing the features in penciled loops connected by a line with notes written on the margin, such as "omit this line," "turn at an angle of ° from true north," "add," "cut out." preliminary preparation of maps. the base map that generally accompanies a report may be an original field sheet or it may have been compiled from various sources by an author and made to incorporate the results of his field work. it should not be a collection of maps of different scales and standards to be worked into a new map. the source of the data shown on every original base map should be indicated on the map, whether it is to be used as an illustration or as a record of field work. this information is required as a permanent record for showing the reliability of the map, for use in comparing data, and for giving full credit to those who are responsible for the data. an author should see that this requirement is observed in order that proper credit may be given and should especially see that all cooperative agreements and organizations are properly mentioned. an original map should preferably be complete in itself. it should not consist of several parts or sheets unless the data to be represented are unusually complex. all elaborate or technical finish of border lines, lettering, or like features should be left to the draftsman or the engraver. base maps that involve the compilation of new data should be prepared by either the topographic branch or the division of alaskan mineral resources. if a base map already published is to be reused it should be submitted to the chief topographic engineer or to the chief of the division of alaskan mineral resources for approval. this procedure will insure a single standard of geographic accuracy in maps appearing in survey publications. a geologist who requires a base map that includes new topographic data should address a request for its preparation to the chief geologist, who, through the director, will refer the request to the topographic branch. the request must be accompanied by a full statement regarding the proposed report and the time when it is likely to be submitted. the preparation of such base maps by draftsmen in the division of geology, the land-classification board, the water-resources branch, or the section of illustrations has been discontinued except for the minor adaptations provided for above. if a report requires the preparation of a base map that includes no new topographic data such a map must be compiled from other authentic maps by the division or branch in which the report originates. if, however, no draftsmen are available in that division or branch, an arrangement can be made with any other branch--as the topographic or publication branch--that may have draftsmen available, with the understanding that the cost of the work shall be reimbursed to the branch doing the work by the branch ordering it. for indicating geologic and other data, however, an author may make use of an authentic base map already published, and after it is reduced or enlarged to appropriate scale by photography such a map may suffice for transmittal with a manuscript. material available for base maps. the maps already published by the geological survey[ ] and other government bureaus should always be consulted when a new base is to be compiled. the following list includes most of the maps available: . the survey's regular topographic atlas sheets, published on three scales-- -minute sheets, scale, : , ; -minute sheets, scale, : , ; -minute sheets, scale, : , --approximately mile, miles, and miles to inch, respectively--and its "special" maps,[ ] some of which are published on other scales. all these maps can be used as bases for detailed geologic maps, for compiling maps on smaller scales, and for revising other maps. . the united states part of the international map of the world, now being published on the scale of : , , (approximately miles to inch). each sheet of this map represents an area measuring ° of longitude and ° of latitude. the published sheets of this map may be used as bases for general maps. the sheets are drawn on the scale of : , , and photolithographs on this scale are available for use as bases for geologic or other maps. the adaptability of the : , , scale map to use as a base for general geologic maps is shown in the geologic maps of the southern peninsula of michigan and of indiana in monograph (pls. iv and vii), the map of florida in bulletin (pl. i), and the map of vermont in water-supply paper (pl. i). . the survey's two-sheet wall map of the united states, by inches, scale : , , (approximately miles to inch). parts of this map can be used as bases for general geologic or other maps and as copy for index and other small diagrammatic maps. this map is published both with and without contours. . land office maps and township plats. these maps are now being published on a scale of miles to inch; they are also photo-lithographed on one-half that scale, or miles to inch. the township plats are printed on a scale of one-half mile to inch. the maps are especially useful in compiling maps in which land lines (townships and sections) are essential, and the township plats afford valuable detail and are useful in field work and in revising other maps. township and section lines should appear on all land-classification maps published by the survey. on maps on a scale less than : , only the townships should be shown; on maps on scales greater than : , the sections should be shown; on maps on a scale of : , the sections should be shown, unless their representation will materially impair the legibility of the map, in which case only the townships should be shown. (see fig. .) . post-route maps, covering single states or groups of adjacent states, published on sheets of different sizes and on scales determined mainly by the size of the state. the map of texas is published on a scale of miles to inch, that of virginia on a scale of miles to inch, and that of west virginia on a scale of miles to inch. both the land office and the post-route maps are useful for reference in compiling maps on smaller scales. post-route maps are especially useful for comparing and verifying the location of cities, towns, and railroads. . coast and geodetic survey charts, published on scales that are governed by the area represented and the amount of detail to be shown. these maps should always be used in compiling and correcting coast lines. . maps and charts published by the corps of engineers of the army, the mississippi river commission, the surveys of the great lakes, and the boundary surveys. these maps are especially useful if the scale of the map to be compiled requires considerable detail. . the survey's three small base maps of the united states--(_a_) a map by inches, scale miles to inch, which is published both with and without contours, or with relief or hypsometric shading; (_b_) a map by inches, scale miles to inch; (_c_) a map - / by inches, scale miles to inch, designed for use as a two-page illustration in a bulletin or a water-supply paper. . the century, rand mcnally & co.'s, cram's, stieler's, the times, johnston's royal, and county atlases. . state and county maps. . railroad surveys, which are useful in furnishing data for elevations as well as for locations of towns and stations. . the latest national-forest maps and proclamations. it is, however, not necessary that national forests, bird reservations, and national monuments be shown on a map in a report unless their addition is specially requested by the author or by the chief of the branch submitting the report, and they should not be shown if they will obscure other more important data. [footnote : see "topographic maps and folios and geologic folios published by the united states geological survey" (latest edition).] [illustration: figure .--diagrams showing principal, guide, and auxiliary meridians, standard and special parallels and correction lines, and system of numbering townships, ranges, and sections.] the survey has published numerous maps of parts of alaska, as well as other maps, which are available for use or reuse in its reports. copies of all base maps for which copper plates have been engraved by the survey can be obtained on requisition, and their use in a new report will save time as well as the cost of engraving. other maps will be found in the survey library, where the latest editions only should be consulted. basic features of maps. it must be remembered that "every map, whatever its scale, is a reduction from nature and consequently must be more or less generalized."[ ] the degree of generalization in the geologic and other detail to be shown on a map usually involves a corresponding degree of generalization in its base. absolutely true generalization means the same degree of omission of detail for each kind of feature. if a base map on a scale of mile to inch, prepared with the usual detail, were placed before a camera and reduced to a scale of miles to inch, the lines representing the smaller tributaries of streams and the smaller water bodies, as well as many other features, would probably be so greatly reduced in length as to be illegible. if from this reduced photograph a new map were prepared, from which all features not plainly discernible were omitted, the new map should represent what might be called true generalization. this degree of generalization is, however, not practicable, but unessential detail should be systematically omitted. the amount of detail which a base map should show is limited by its scale, by the character of the country it represents, and by the kind of data to be shown. coordinate features of a topographic map should be shown with equal detail. detail in culture may call for detail in drainage, though relief may be greatly generalized or entirely omitted; detail in relief may like-wise call for detail in drainage, though culture may be more generalized. [footnote : gannett, henry, a manual of topographic methods: u. s. geol. survey mon. , p. , .] if the three fundamental features of a topographic map--the culture, the drainage, and the relief--are to be engraved or photo-lithographed separately and printed in colors, the best results can be obtained by drawing each feature in a separate color on one sheet unless the work is coarse and great precision in register is not needed. the culture should be drawn in black waterproof ink, the drainage in prussian blue, and the relief in burnt sienna; but care should be taken that the colors used will photograph well. to insure a good photograph it is usually necessary to add a little black to the blue and brown. (see "inks," p. .) the photographer will then make three negatives and will opaque or paint out all but one of the three features on each negative. the cost is somewhat greater than that of reproducing three separate drawings, but the result gives more accurate register than if the drawings were made on separate sheets, which are likely to change in size before they are reproduced. standard scales. the standard scales of the maps used in the publications of the geological survey are fractions or multiples of : , , (see p. ), except for a map that is reduced expressly to fit one or two pages of a report or that is reduced horizontally or vertically to fit the text as a small diagrammatic or index map. it should be remembered that a map which may be serviceable for use in compiling a new map, except as to scale, can be reduced or enlarged to the scale of the new drawing by photography, by a pantograph, or by other means. (see p. .) maps compiled by an author should be prepared on a scale of at least - / times and preferably twice the size of the scale used on the published map. maps traced on linen should be no less than twice the size of publication. not only is the quality of the reproduction improved by considerable reduction, but the larger scale of the drawing facilitates the plotting of details. it should be remembered, however, that a linear reduction of one-half produces a map only one-fourth the area of the original, and reduction so great may prevent the addition of data, such as an extended note in small letters applying to a small area on the face of a map, which would not be legible when reduced. orientation of maps. a map that bears no arrow indicating north is supposed to be oriented north and south, and its title should read from west to east. if, however, the area mapped has a general trend in one direction, as northwest to southeast, and its squaring up by a north-south line would leave too much blank paper, this general rule is not followed. the border lines on such a map should conform to the general trend of the area mapped, an arrow should show north, and the title and scale should be placed horizontally, but the projection numbers and town names should follow the direction of the parallels of latitude. (see pis. x and xii, bull. ; and pis. vi, xv, and xvi, mon. .) projection.[ ] [footnote : see also pp. - , where the method of projecting a map is more fully explained.] the polyconic projection has been adopted by the geological survey for its topographic atlas sheets and must be consistently used for its other maps. if a new map is to be compiled an accurate projection should first be constructed, and no plotting should be done on it until the projection has been checked and found to be correct. a projection should be checked or proved by some one other than the person who prepared it. next the drainage and the water areas should be outlined; then the cultural features should be added; and finally the relief, whether expressed by contour lines, hachures, or shading.[ ] [footnote : see pp. - for methods of tracing and transferring.] explanation. under the heading "explanation" should be placed all matter needed to describe fully the details of an illustration, whether map, diagram, or section, so that if the illustration became detached it would be a complete self-explanatory unit. the explanation of a map may be placed inside the border lines if there is ample room for it, or it may be placed outside. the standard arrangement for an outside explanation for geologic maps is shown, in the geologic folios, which should be followed in general form. if there is space within the border lines the explanation may be appropriately arranged therein, either in a vertical column or horizontally, according to the size and shape of the space available. if the sequence of formation is shown by horizontal arrangement the younger formations are placed at the left and the older at the right. if it is shown by a vertical arrangement the youngest formation is placed at the top. each original map submitted by an author should have at least - / inches of blank margin on the right and at the bottom in which to place the explanation, scale, title, and other matter, but the author should make no attempt to elaborate these features nor should he employ a draftsman to letter them carefully. plainly written ordinary script is quits sufficient for original maps; the final lettering, which may consist entirely of impressions from type, will be added after submittal of a report. titles of maps and other illustrations. the titles of maps should be supplied by authors but are subject to revision in order to make them agree with established forms. they should be written in ordinary script, not carefully lettered. they should state concisely the kind of map, the area shown, the special features represented, and the county, state, or territory in which the area is located. (see p. .) titles are reproduced directly only on lithographs, three-color prints, photogelatin plates, and other illustrations that are printed by contractors, not by the government printing office. the titles of illustrations that are reproduced by relief processes, such as zinc etching, half tone, and wax engraving, are printed at the government printing office from type, and proofs are submitted to the authors for examination. symbols used on maps. general features. more than symbols have been used on maps to express different kinds of data, a fact indicating at once a notable lack of uniformity and a need of standardization. it is of course impossible to provide a characteristic symbol that can be used uniformly for each kind of feature, and therefore the same symbol may be used on different maps to express different things. the symbols shown in plate ii are those most used on geologic maps. the symbols for dip and strike, fault lines, mine shafts, prospects, and several others are generally well known, but on some maps it may be necessary to modify a standard symbol to express additional distinctions. the symbols shown, however, will cover all the ordinary requirements of miscellaneous mapping. though the plate shows more than one symbol for some features the symbol most commonly used is given first and should be preferred. the center of each symbol should mark the location of the feature symbolized. symbols are not always platted with sufficient care. on small-scale maps they are difficult to locate and unless great care is taken in platting them they are likely to be several miles out of place. all symbols should be located precisely where they belong. the symbol showing dip and strike should be accurately platted by means of a protractor, so that the strike will be shown graphically, without a number and a degree mark, and not need replatting by a draftsman or engraver. the dip, however, should be indicated by a number and a degree mark. letter symbols. the letter symbols used on most geologic maps to indicate the ages and names of the formations represented consist of two or more letters--an initial capital letter for the name of the system and one or more lower-case letters for the name of the formation or of the material, as qt (quaternary--lower terrace deposits); cpv (carboniferous--pottsville formation); cok (cambrian-ordovician--knox dolomite), etc. the standard usage for this feature is shown in the geologic folios but is subject to modification in other publications. in preparing an original geologic map a letter symbol, such as has been just described, or a number should be put in the proper place in the explanation, and the same symbol or number should be repeated at one or more places on the map within the areas to which it refers. each area that is indicated by a color should be marked with the proper symbol in order to make its identification sure, for light colors especially are likely to fade and mixed colors can not be discriminated with certainty. [illustration: u. s. geological survey preparation of illustrations plate ii symbols used on geologic maps, economic maps and mine plans] oil and gas symbols. a complete set of symbols for maps showing oil and gas is given on plate ii. referring to these symbols the chief geologist, in a memorandum to the director, writes: the symbols used by the survey in its oil and gas maps have not been in accord with those used by the oil companies, nor have they been wholly logical. it appears that though they were submitted for recommendation they never have been formally approved. herewith i submit a code prepared by the geologists of the oil and gas section. they conform largely to commercial use and embrace its best features as well as the best and most logical features of our previous usage, the departures from which are, after all, of minor consequence. the symbols here submitted [see pi. ii] with recommendation for approval are founded on a building-up system, so that the history and the results of drilling at any location can be recorded by slight additions to symbol and without erasure. thus maps may be revised without scratching. in drawing these symbols the draftsman should make the rays of the gas well distinct and in adding the vertical bar or line showing that a hole is dry or abandoned should make it long enough to be distinct. it would be preferable to draw this bar obliquely, but an oblique position would coincide with some of the patterns on certain maps, and it should therefore be placed vertically. the vertical line indicates the failure or abandonment of the well, the symbol for which is thus scratched off or canceled by the line drawn through it. the symbols agree so far with commercial usage that oil men will have little need to consult the explanation. symbols for use on maps showing features of ground water. the symbols used on maps relating to ground water represent the features named below, each of which has been shown in publications already issued. area of absorption or outcrop. area that discharges ground water. depth to water table. quality of ground water. contours of water table. area irrigated with ground water. fluctuation of water table. nonflowing well. depth to water-bearing formation. flowing well. structure contours of water-bearing unsuccessful or dry well, formation. well with pumping plant. area of artesian flow. spring. head of artesian water. the lack of uniformity in the symbols commonly employed to represent these features is due to differences in the number of color on the maps and differences in the scale. standard colors for the larger features, such as those for areas of artesian flow, areas of absorption, and curves showing depths to water table or to water-bearing formations, can not be fixed, because of considerations of economy in printing. for example, if light green is the standard color to be used for delineating areas irrigated by ground water and no green is used on other parts of the map its use would represent an additional or special printing, whereas a tint of blue, brown, or purple, if any of these colors is used for other features on the map, might be used also for this feature without additional printing. therefore the general use of any particular color for a water feature seems to be impracticable; but this fact should not preclude the adoption of color standards for use subject to the requirements of economy in publication. the ordinary symbols for wells are the open circle and the solid circle, or dot. only in the secondary or specific well symbols does there appear to be lack of uniformity, the choice of secondary symbols being governed either by personal preference or by the requirements for specific distinction. all symbols should, if possible, suggest the things they represent. wells are circular and hence the open circle is most used and most appropriate for nonflowing wells. to indicate a flowing well the circle is made solid, denoting that the well is full of water. for an unsuccessful well the most suggestive symbol would be an open circle with a line drawn through it to denote cancellation. it has been suggested that if water features, including wells, are to be printed in blue, unsuccessful wells, or dry holes, be printed in black. a large circle drawn around the symbol for a flowing or nonflowing well will appropriately denote a pumping plant at the well. the accepted symbol for a spring is a dot with a waved tail representing the direction of flow, if known. this symbol can not be modified without destroying its prime characteristics, but it may be accompanied by a letter indicating the kind of spring. an open circle with a tail might be used on large-scale maps, but it would be out of scale on other maps, whereas the black or blue dot and tail will fit maps of any scale. the following colors and symbols can most appropriately be used to represent ground-water features. the well and spring symbols can be varied by adding letters if they are necessary to express other data than those indicated in the list below. _general ground-water features._ area of absorption or outcrop: flat color used on the map to show the geologic system in which the absorbing formation occurs. areas showing depths to water table: shades of purple and gray; if possible the shades showing the areas of least depth should be darkest and the shades should grade from those to lighter tints. contours of water table, or contours on water-bearing formations: gray or purple curves or lines. areas of artesian flow: blue flat tint, or fine ruling in blue. depth to water-bearing formations: gradation of a single color or of two related colors from dark for shallow depths to light for greater depths. nonflowing artesian areas (pumped wells): green flat tint, or fine ruling in green. depth to water-bearing formations shown by gradation of tint if possible from dark for shallow depths to light for greater depths. head of artesian water: blue curves or lines. areas that discharge ground water: blue flat tint, or fine ruling in blue. areas irrigated with ground water: green flat tint, or fine ruling in green. [illustration] well, character not indicated. [illustration] well, nonflowing. [illustration] well, flowing. [illustration] well, unsuccessful or dry. [illustration] well, nonflowing, with pumping plant [illustration] well, flowing, with pumping plant. [illustration] springs. [illustration] spring, thermal. [illustration] spring, mineral. the standard color scheme should be used if no conditions preclude its use, but if other colors can be used with greater economy without sacrificing clearness the use of the standard colors should be waived. black-line conventions. a complete set of the black-line patterns used to distinguish areas on a map is given in plate viii (p. ), and their application to a finished drawing is shown in figure (p. ). these patterns, however, should preferably not be used by the author in his preliminary work on an illustration. for this purpose water colors or colored crayons are preferable, and the distinctions between areas may be emphasized by letter symbols. materials used in preparing maps. paper. for large and important maps which may at some time be extended to cover a greater area or which may be made to fit maps already prepared or published the paper used should be mounted on muslin to reduce to a minimum the shrinking or stretching caused by atmospheric changes. pure white paper produces a better negative than a cream or yellowish paper and will retain its color longer, but all papers become more yellow with age and exposure to light. the following brands of paper are used in the survey in the preparation of maps: "normal" k. & e., unmounted. has an excellent surface and comes in flat sheets, by , by , and by inches. "paragon" k. & e., mounted on muslin. in -yard rolls inches wide. used in the survey for large office drawings and maps of large scale. "anvil" k. & e., mounted on muslin. in -yard rolls , , and inches wide. used in the survey for large drawings. "whatman's hot pressed," unmounted or mounted on muslin. in sheets ranging in size from by to by inches. an excellent paper for maps. the muslin-backed paper is recommended for use in preparing large detailed maps and base maps that are to be retained as permanent records. the muslin provides a durable and flexible backing that permits the map to be rolled, and paper thus mounted is particularly serviceable for a map which may be subjected to considerable revision and to which must be added finally a title, explanation, and other marginal matter. "ross's relief hand-stipple drawing paper." a stiff enameled or chalk-coated paper whose surface has been compressed into minute points that stand in slight relief so that a shade made on it with pencil or crayon is broken up into dots and can be reproduced by photo-engraving. for use in making shaded drawings, drawings showing relief by light and shade, etc. similar paper is prepared for parallel-line and other pattern effects. in sheets ranging in size from by to by inches. (see p. for method of using.) profile and cross-section paper. in sheets of convenient sizes or in rolls. bears lines printed in blue, green, red, or orange, in many kinds of rulings, which may be selected by reference to catalogues. profile and cross-section paper printed in orange is recommended for preliminary drawings; blue is recommended for drawings that are made in pencil and submitted for inking in. bristol board. for the smaller maps, such as key maps and maps less than by inches, and for small drawings made for direct reproduction, reynolds's bristol board is recommended on account of its pure-white color and its hardness, which permits erasures to be made without affecting redrawing over the corrected area. it is obtained in -ply, -ply, and -ply sheets. the -ply and -ply are especially useful in making delicate brush and pencil drawings and pen and ink drawings. the sizes used in the survey are - / by - / , - / by - / , and - / by - / inches. tracing linen. tracing cloth or linen is especially useful for large work that will require considerable reduction. (see p. .) its advantages are that a tracing that has been carefully made on it over any kind of copy for direct reproduction by a photo-engraving process can be used for making a paper negative for contact printing or blue printing. on the other hand, it is susceptible to atmospheric changes that affect scale, and the lines traced on it are not reproduced as sharply as those made on paper. it can be obtained in rolls to inches wide. erasures should be made on tracing linen with a hard rubber eraser, not with a sand rubber or a steel eraser. inks. the best drawing inks are in liquid form, ready for use. they should be waterproof and equal to the grade known as higgins's waterproof ink. when a suitable waterproof blue ink can not be obtained, a good blue for features of drainage can be made by dissolving a half pan of winsor & newton's prussian blue in water. no good waterproof burnt sienna ink seems to be obtainable, but a good substitute can be made by dissolving winsor & newton's water color of that name. ink lines should be drawn in full strength of color--lines that should be black must not appear grayish, for example--and pens should be kept clean. the same pen should not be used for applying two inks, as the mixture thus produced is likely to thicken or coagulate on the pen. a little black should be added to colored inks that are used in making drawings to be reproduced in colors in order to strengthen the lines for photographic reproduction. drawing pens. the pens made by keuffel & esser, especially their no. , and gillott's nos. , , , and give complete satisfaction. the gillott numbers are given in the order of fineness of the points. no. being the finest. the best cleaner for a drawing pen is a piece of chamois skin. pencils. pencils used for drawing should have leads of a quality equal to those of the koh-i-noor brand, in which the grades of hardness are indicated by b, b, b, hb, f, h, h, h, h, h, h, h, h, and h; the softest grade is b and the hardest h. the grades most generally used are b, hb, f, h, and h. rubber erasers and cleaners. two kinds of rubber erasers are usually employed in making erasures on drawings--a hard, dense rubber like the "ruby," and a soft, pliable rubber like the "venus" or "h" (hardtmuth). the soft rubber is also useful for cleaning large surfaces. art gum is also recommended for this purpose and has the advantage of not disturbing the surface of the paper. colored pencils and crayons. colored pencils and crayons are useful only for coloring preliminary maps. they are not recommended for use on maps that are to be kept for reference or to be submitted for reproduction, because the colors rub off, but they can be used on photographic prints of base maps or on transparent oversheets, for which the unglazed side of tracing cloth is well suited. when they are so used register marks should be added at numerous points on the map and the oversheet, including the four comers, the color boundaries should be drawn or traced, and finally the colors should be added. two or more colors should not be used on any one area to modify a tone, but each area should be colored with a separate crayon. patterns or designs should not be used except to strengthen contrasts, and for that purpose a pattern may be drawn with a black pencil over a color. water colors. by dilution to half strength some of the standard water colors will yield a tint or hue that will contrast with other tints or hues produced in the same way quits as well as undiluted or full colors will contrast with one another. the colors named below, except chrome-yellow and emerald-green, are among those that when diluted will afford satisfactory contrasts among themselves and with their full colors and are recommended for use in coloring original maps. mauve. hooker's green no. . crimson lake. emerald-green. orange-vermilion. payne's gray. burnt sienna. lampblack. cadmium-yellow. sepia. chrome-yellow. cerulean blue. olive-green. other pigments spread better than cerulean blue and emerald-green, but the exceptional purity of color of these two seems to warrant their use. japanese transparent water colors. japanese transparent water colors, so called, are used by some geologists. they spread evenly and are convenient for field use, but they can not be washed out like other water colors, so that when they are once applied to an area and a change of color becomes necessary they must be bleached out. a good bleach is sodium hypochlorite, which should be applied with a brush until the color disappears, and the area dried with a blotter before recoloring. light tints of these colors are believed to be somewhat fugitive if exposed to strong light. coloring geologic maps. the colors used on most original maps are not pleasing, a fact that is of no particular importance, but--and this is of importance--they often fail to give clear distinctions; the separate areas can not always be identified or distinguished with certainty. again, some colors are fugitive, and when laid on in light tints they disappear entirely or become uncertain. much of the difficulty in identifying and discriminating colors on an author's original maps is due to the promiscuous mixing of colors. many persons can not match or discriminate mixed or broken colors. hence if the supply of a color produced by mixing becomes exhausted and the attempt is made to duplicate it by a second mixture the two will probably fail to match. it is therefore suggested that colors in full strength and colors diluted to half strength be used instead of mixtures of two or more pigments, so that one color in two strengths or tones can be employed to indicate areas that are to be distinguished. the colors listed on page will give satisfactory distinctions and will thus supply all demands for map coloring. to insure satisfactory contrasts between colored areas on a map, unlike colors should be placed next to each other--that is, colors should be placed together that are widely separated in the spectrum, such as yellow and mauve, red and green, blue and orange, burnt sienna and olive-green; not such as red and orange, blue and purple, orange and yellow, sepia and burnt sienna. a sufficient quantity of water and color pigment to be used for one formation area on a map should be stirred in a saucer until the desired tint is produced before it is applied. to maintain the same tone properly the color should be well stirred every time the brush is filled; if it is not stirred the brush will on the next dipping take up a lighter tint, because most pigments, especially those derived from minerals, tend to precipitate. when the colors are applied the map should preferably be placed in a slightly inclined position, and the coloring should be started at the upper boundaries of an area to be colored, the well-filled brush being pulled toward the painter and worked rapidly back and forth horizontally, the edges of the fresh color being kept wet. if the edges are allowed to dry, a hard line and a smeared or uneven effect will be produced. a strong color should generally be used for small areas unless the map shows also large areas that must have the same color; lighter hues should be used for large areas. bright colors are best suited for areas of igneous rocks, dikes, and veins, and these may be reduced in strength for the larger areas. the survey's color scheme (see p. ) need not be applied at this stage of preparation, except in the most general way. appropriate final colors can be best selected when the new map is made ready for engraving. in the author's original maps adequate color distinctions between areas are more important than the use of standard geologic colors. patterns should not be ruled in one color on an original map to indicate distinctions between different formations of the same age or period, because such patterns are difficult to produce by hand with proper uniformity except by engraving. it is of vital importance that an original base map should be free from colors and from technical symbols in order that it may be kept clean for photographing and preserved for possible future use. such a map should preferably be photographed in order to obtain prints on which to add the colors and symbols; the use of an oversheet for this purpose is not nearly so satisfactory. when photographed a base map should be reduced to publication scale in order to save the additional cost of a larger negative, and this reduced map may be made up for publication by the addition of colors and symbols, title, explanation, etc.; but the lithographer will also need the original base map from which to make his reproduction. diagrams. essential features. the term "diagrams," as used here, includes such illustrations as mine plans, profiles, sections, stereograms, and maps that are more diagrammatic than cartographic. the first essential in the original drawings for simple diagrams is clearness of copy. simplicity of subject does not warrant hasty preparation, for an original sketch that has been carelessly drawn and is inaccurate or inconsistent in detail may lead to serious errors. ruled paper printed especially for platting profiles and cross sections should be used. curves or graphs made by an author with pencil on blue-lined section paper may be inked by more skillful draftsmen. an author's pencil sketches are usually satisfactory if they indicate plainly the facts to be represented, but they should be prepared with some care as to detail. tables and like matter are not generally satisfactory material from which to prepare drawings. in drawings for diagrams that are to be printed in the text as figures the use of large, solid black bars or of conspicuous areas of solid black is objectionable, because the black is likely to print gray and to appear uneven in tone. ruled tints or cross lining give better effects. stereograms should be prepared by an author with especial care, for they represent facts only as the author sees them, and the author's view must be imparted to the draftsman graphically. the "third dimension"--the relief--in such drawings is not easily expressed and should be brought out clearly in the author's rough sketches. for illustrations of apparatus photographs are preferred, but if rough sketches are submitted they should show not only correct relations but all dimensions. plans of mine workings. blue prints obtained from mining companies are acceptable for plans of mines or underground workings, but all unnecessary or irrelevant details on such plans must be canceled and all essential features retained, and every essential feature, especially any added data, must be clearly interpretable. many such blue prints are so large and unwieldy that they must be greatly reduced by photography before they can be redrawn. if the lines are too weak to photograph, a tracing of the essential parts can be made and reduced to about twice publication size. the shadowless drafting table, described on pages - , is well adapted to the work of making such tracings. blue prints can also be pantographed to any convenient size if the details are not too minute or complex. [illustration: figure .--conventional lines used in preparing plans and diagrams of mine workings to distinguish different levels.] the levels in plans of underground workings can be differentiated in finished drawings by a system of conventional outlines in black, as shown in figure , by conventional patterns or symbols within plain outlines, or by colors. such plans should not be printed in colors unless the maze of workings is so complex that lines showing the different levels would become confused or obscure if printed in black. sections. the standard forms of geologic sections are shown in the geologic folios. structure sections should be prepared with great care as to detail but without attempt at refinement of lines and lettering. the author's drawing of a section along a line or zone that is not definitely indicated by a line on an accompanying map should be so prepared that it may be copied exactly. on the other hand, the draftsman, in reproducing a section that represents the structure along a given line or zone, may be able to make the outcrops coincide with the topography and the formation boundaries shown on the map, but the structure, or the interpretation of it to be given, should be carefully worked out by the author. all essential facts relating to bedding, folding, faulting, crosscutting dikes and veins, or other significant details should be indicated with precision. no attempt need be made to draw firm, steady lines so long as the essential facts are clearly expressed. all sections should be drawn to scale, and both the vertical and the horizontal scale should be given on the drawing. these scales should be uniform if possible, or at least the vertical exaggeration should be minimized. too great vertical exaggeration creates distortion and is grossly misleading. sections should be drawn to scale on ruled paper prepared for the use of authors. such paper may be obtained on requisition. [illustration: figure .--section and perspective view showing relations of surface features to the different kinds of rock and the structure of the beds.] a kind of cross section which is not often used but which gives a more pictorial and clearer conception of underground relations than other kinds is made by adding a sketch of the topography above the section. this sketch should be a perspective view, in which the prominent features shown hypothetically in the section below it will be reflected in the topography. such a sketch might show, for example, not only monoclinal slopes, "hogbacks" due to steeply upturned beds, terraces, escarpments, and like features, but volcanic necks or other extruded masses in their true relations to the underground geology of the country. (see fig, .) in submitting the draft of such an illustration the author should, if possible, submit also a sketch or photographs of the adjacent country and indicate on the section the point of view by notes such as "sketch a made at this point," "see photograph b." the sketch will be more useful if it is prepared on a scale consistent with the details of the section. it may be made with a pencil and should show as well as possible the relations of the features in the landscape to those in the section. some good examples of illustrations of this type can be found in powell's "exploration of the colorado river," pages - . one simpler figure of the same kind is given on the cover of the geologic folios. in preparing original drawings representing columnar sections, or sections in wells or ravines, the author should indicate all well-defined or important local features of structure, such as cross-bedding, ore bodies, or lenses. if there are no unusual features or details, the subdivisions need be identified only by names of materials, such as "thin-bedded limestone," or "slates with some coal," the coal beds being shown. the sections should, however, be so plotted and subdivided by the author that each section or group of sections will be complete in its crude form. the compilation of various parts into one unit and the construction of columnar sections by reference to tables alone is an essential part of the author's original preparation. [illustration: figure .--sections of coal beds. the figure shows the publications size and the arrangement at the sections. each section should be drawn three-tenths or four-tenths of an inch wide and reduced one-half. thicknesses can be indicated by numbers, as shown on sections and , or by bar scale.] sections designed to show the relative thickness of beds of coal, arranged in groups for publication either as plates or figures, should be drawn in columns three or four tenths of an inch wide and reduced one-half, as shown in figure . these sections, whether correlated or not, should be drawn to some definite vertical scale and should show the thickness of the coal beds, preferably by numbers indicating feet and inches, the other material being symbolized and the symbols explained graphically, as shown in figure . the vertical scale should always be stated for the use of the draftsman. a bar scale may be used instead of figures showing the dimensions of the individual beds. lithologic symbols. the symbols used to indicate the various kinds of rocks illustrated in sections and diagrams are shown in plate iii. the units or elements of these symbols may be spaced more openly in generalized diagrammatic sections than in sections that show great detail. symbols should be used consistently throughout a report, and in order to make them consistent a set showing the symbol to be used for each kind of rock to be indicated should be prepared before the original drawings are made. some inconsistencies may be unavoidable on account of the small size of some areas shown and the contrast needed between others; but the deviations from the set of symbols adopted should be minimized. use of photographs as illustrations. essential features. the foundation of a good photographic print is a good negative, and the best prints for reproduction as illustrations are those made from negatives in which the illumination is evenly distributed and the details are sharp--such negatives as are obtainable only by the use of small stops and correct focusing. a good print should not present too sharp contrasts between its dark and its light parts; if it does, the printed reproduction will show a loss of detail in both. sufficiency of detail depends largely on focus, stopping down, and timing; brilliancy is the direct result of ample illumination by sun or artificial light, without which a photograph will be dull or "flat" and generally unsatisfactory for reproduction. bad weather may prevent good field exposures, yet even in bad weather acceptable negatives may be obtained by judicious focusing, stopping down, and timing. if a negative is overexposed it may be full of detail, but flat and too thin to print well. if underexposed it will show no details in its lighter parts and the shadows will be black; and a black shadow is nothing less than a blemish. some detail should appear in all shadows and in the middle tones, and some should appear in the high lights; and a print in which these are evenly developed and in which the illumination is distributed uniformly is technically perfect. unfortunately not all field photographs are good, so an author must select from his collection those which will make the best half tones. in making this selection he should of course consider, first, the scientific value of the photograph, and next, its pictorial or artistic quality, which, though of secondary importance, should nevertheless be kept in mind. a feature worthy of illustration deserves good pictorial expression; if it is of superior scientific interest it should not be represented by an inferior photograph. fortunately, a good, accurate drawing may be made from a poor photograph, and a photographic view that has only minor defects can be successfully retouched. photographs that need much retouching should generally be larger than publication size, for the effects of retouching--brush marks, etc.--will be softened by reduction. photographs that need only slight retouching need not be larger than publication size. a photograph can rarely be satisfactorily enlarged in reproduction unless it is sharp in detail and requires no retouching. [illustration: u. s. geological survey preparation of illustrations. plate iii. lithologic symbols used in structure and columnar sections to represent different kinds of rock] unmounted prints are always preferable for use in making illustrations. a group that is to form a single plate should be placed in an envelope bearing the number of the plate and its title, and each print of the group should bear a corresponding number, written in pencil on its back. the envelope will protect the prints and keep them together, and the numbers will identify them. red ink should not be used to mark photographs, as it is likely to penetrate the coating or even the fiber of the paper, so that it can not be erased. if a print is of doubtful quality two copies of it should be submitted--one glazed, the other having a dead finish or "mat" surface, which is generally preferable if the print must be considerably retouched. the best prints for use as illustrations are those made on "regular" or "special" semimat velox and glossy haloid papers. the author should indicate prints that may be grouped together according to their relation geographically or by subject. generally two half tones will be combined on a page, and the list of illustrations should be prepared accordingly. with slight trimming and reduction, three photographs measuring - / by - / inches may be made up one above the other to form a full-page octavo plate. four photographs in which the longer dimensions represent vertical distances may sometimes be used if they are placed sidewise on the page, with side titles. some photographs may be reduced to the width of a page by trimming instead of by photographic reduction, which may involve loss of detail. the author should clearly indicate the extent of such trimming as they may bear without loss of essential details. the trimming is best done during the final preparation. a line should not be drawn across a photograph to mark such trimming, but the position of the line or lines should be indicated either on temporary mounts, on the backs of the prints, or by a statement, such as "one inch may be cut off on right, one-fourth inch on left, and one-half inch at bottom." copyrighted photographs. section (ch. , title ) of the revised statutes, amended by act of march , (stat. l., vol. , p. ), provides that no copyrighted photograph may be used without the consent of the proprietor of the copyright in writing signed in the presence of two witnesses. a penalty of $ is imposed for every sheet on which such a photograph is reproduced without consents, "either printing, printed, copied, published, imported, or exposed for sale." an author should therefore obtain the written consent of the owner of a copyrighted photograph to use it, and the letter giving this consent should be submitted with the illustration. sources of photographs. every photograph submitted with a manuscript should bear a memorandum giving the name of the photographer or the owner of the negative. if the negative is in the survey's collection that fact should be stated, as "neg. keith ." the survey receives many requests for copies of photographs that have been reproduced as illustrations in its publications, and replies to these requests will be facilitated if the survey's number or the source of each photograph presented for use as an illustration is stated as above on the photograph. lending original photographs and drawings. a photograph that has been used in making a half-tone cut for a survey report can not be lent, but if the negative is on file a print can be furnished at cost; and a survey drawing that is well preserved can be photographed and a print furnished, also at cost. requests for such prints should be addressed to the director. unpublished photographs. the survey can not issue a copy of an unpublished photograph except upon the written approval or requisition of the person under whose name the negative is filed. this requirement does not apply to a print needed for official use, nor to a print made from an old negative reserved under the name of any present member of the survey or from a negative that has been released by the person under whose name it is filed. authors using survey photographs in unofficial publications are requested to acknowledge the source of the photograph by adding to the printed title such a statement as "photograph by u. s. geological survey (david whits)." specimens. general requirements. specimens other than fossils that are to be illustrated in a report should be photographed before they are submitted, but the requisition for the photographs should be initialed by the chief illustrator, who will indicate the kinds of prints needed. duplicate photographs of the specimens should be made up into temporary plates by the author and submitted with his other illustrations, the specimens being retained subject to call, if needed, when the illustrations are finally prepared. should a colored illustration of a specimen be needed, however, the specimen must be submitted with the report, and a different kind of print, preferably one made on platinum or other special paper, will be obtained by the section of illustrations. borrowed and fragile specimens. in submitting specimens to be illustrated an author should call attention to those that have been borrowed and to those that are fragile. borrowed specimens will receive first attention, so that they may be returned promptly. transmittal of paleontologic specimens. all requests for paleontologic illustrations should be addressed to the director. the letter of transmittal should state the title of the paper, the form of publication desired (bulletin, professional paper, or monograph), and the status of the manuscript, whether completed or in preparation. if the paper is unfinished an estimate of the number of illustrations required should be given, and the special reasons for prompt preparation should be fully stated. a letter transmitting a second or third lot of fossils should refer to the preceding lot or lots if all the fossils are to be used in illustrating the same paper. fossils that are to be drawn should be sent directly to the section of illustrations, but those that are to be photographed and require unusual posing or that are extremely delicate and valuable may be sent directly to the photographic laboratory to avoid repeated handling. each specimen or, if it is very small, each box or bottle containing a specimen should be numbered, and each lot should be accompanied by a list giving their names and numbers. full instructions as to size of reproduction, together with sketches showing the point of view preferred and any special features to be displayed should also be submitted. all specimens that show strong colors and all groups of specimens that are not uniform in color will be coated by holding them in the vapor of ammonium chloride unless directions to the contrary are given by the author of the paper. as it may not be desirable to apply this process to soft or fragile specimens or to specimens that have been borrowed an author should indicate any specimens that may not be so treated. specimens whose color aids in revealing detail are not so coated. if any features of a specimen are unusual that fact should be stated so that the photographer and the retoucher may perform their work according to the requirements. making up plates. two or more illustrations may be combined to form one plate in order to permit easy and close comparison as well as for economy, for if a particular illustration is too small to make a full plate and is not suitable for enlargement other illustrations that are closely related to it may be put on the same plate. the size of the printed page as given in the table on page will determine the size of the plate. in making up plates composed of a number of figures the author should endeavor to group related figures together and at the same time to observe proper regard for artistic effect, but as figures vary in size and shape a grouping according to relations may not be possible in some plates. if related figures can not be kept together the larger and darker figures should be placed in the lower part of the plate and the smaller and lighter above. if a plate consists of one large figure and several smaller ones the large figure should be placed below and the smaller figures above. a number designating a figure should be placed immediately below the figure, and a series of such numbers should preferably begin with in the upper left corner and continue consecutively across and down through the plate. this arrangement is not always possible, however, on account of variations in the size of figures. as drawings of fossils or other specimens are prepared separately and grouped into plates, and as most paleontologists make up their own plates, each in his own way, there is naturally great dissimilarity in methods and in results. ordinary white or light-gray cardboard should be used, and the figures that are to make up a plate should be arranged as stated above but not securely pasted until the grouping is satisfactory. in trimming each drawing or photograph the author should be careful to leave room at its lower edge for the number. small drawings or photographs, such as paleontologists use, when pasted on bristol board or other board faced with tough paper are difficult or impossible to remove without injury if they have to be remounted; figures pasted on ordinary white or gray cardboard can be removed without difficulty. each plate should be made up in a size to fit the volume or in its correct proportion to a page in the volume in which it is to be used (see table on p. ), and each figure should be properly oriented--that is, all vertical lines, or the vertical axis of each specimen, should be parallel with the sides of the plate. when the figures are being mounted care should be taken that the mucilage or paste does not exude under pressure and cover any part of the drawing or photograph. the same attention should be given to pasting on numbers. inattention to these details may produce results that will affect the reproduction of the plates. ordinary mucilage may be used for mounting drawings and photographs, but photo paste gives good results and is perhaps cleaner to handle. dry-mounting tissue is well adapted to mounting single illustrations but not groups of figures. liquid rubber is sometimes used, but it is not suitable for mounting small figures, such as drawings and photographs of fossils. it can be used satisfactorily for mounting temporary plates and for mounting photographs in albums and on large cards for study or exhibition; but it has not proved to be a permanent adhesive. its special merit is that it does not cause either the photograph or the mounting sheet to warp. it is applied by spreading it evenly over the back of the photograph with the fingers. the superfluous rubber can easily be removed from the hands and from the cards or sheets when it is dry. anything mounted with liquid rubber can be easily removed. if a plate is to be made up of a small number of figures that require different reductions, the author, instead of mounting or pasting the separate figures on one card in the manner already indicated, may draw a rectangle of the size of the printed plate and sketch within it the several figures in their respective sizes and positions. these "dummy" plates or layouts should be numbered as plates, and they may bear captions and titles. the photographs or drawings represented by the sketches should then be numbered to identify them with the sketches on the dummy plate, and those that pertain to each plate should be inclosed in an envelope attached to the dummy plate. a plate made up in this manner will meet every requirement of the photo-engraver or lithographer. if a paleontologist so desires, his plates can be permanently made up after he has transmitted his material, but he should always submit a tentative arrangement. reuse of illustrations. if an author desires to use in modified form an illustration already published, whether by the geological survey or by an outside publisher, he should furnish a print or tracing of the illustration showing the changes desired. if the illustration is not to be modified he need only give the title of the volume in which it was used, with the number of the page, figure, or plate, and he need not make a sketch of the illustration or furnish a dummy; but its title should be quoted and proper reference should be given in the list of illustrations. due credit should be given to the author or publisher. the original cuts of illustrations will be kept for one year after the report for which they were made has been published, and authors of later reports may and should reuse, whenever practicable, any such cut that will serve as an illustration. in the author's list of illustrations such a cut should be referred to by its number as plate or figure and the volume in which it was first used. an electrotype of any cut on hand will be furnished for use in publications other than those of the geological survey at the cost of making, which is - / to - / cents a square inch of printing surface. the minimum charge for a single electrotype ranges from to cents. approval of finished illustrations. after the drawings for a report have been prepared they will be submitted to the author or to the chief of his branch or division for examination. the finished drawings will be accompanied by the "originals," with which the author should carefully and thoroughly compare them. after making a thorough comparison he should mark lightly with a pencil, on the finished drawings, all necessary corrections, or indicate his approval subject to such corrections and additions as may be required. he should verify all type matter and other lettering and assure himself that no mistakes have been made in grouping the photographs into plates, especially such as have been regrouped since they left his hands. the author's list of illustrations will be submitted with the new drawings for this purpose. revision of illustrations. all illustrations receive editorial revision before they are sent to the engravers. after they are drawn they are examined with reference to their scientific features and their accuracy, and then in turn with reference to the correctness of geologic names and geographic names and to errors in statement and in spelling. each illustration thus, before it is completed, receives critical examination by persons qualified in particular kinds of work to detect errors or omissions. submittal of proofs. the first proofs of all illustrations are submitted to an author when he is within reach, but if he is in the field and the transmittal of the proofs to him is likely to cause too much delay they are submitted to the chief of the branch or division in which the report was prepared. second proofs of the more complicated illustrations, particularly geologic maps, may be submitted. an author's examination should be confined principally to the revision of the scientific features of his illustrations, but suggestions as to general effectiveness are always acceptable. the process to be used in engraving each illustration is stamped in its lower left corner. in examining proofs an author should note the following facts: . changes can not be made in zinc etchings except by eliminating parts, cutting away defects, and connecting lines. if additions are required reengraving is generally necessary, and reengraving should preferably be avoided. . changes can be made in half-tone plates only by re-etching certain parts to make them lighter and by burnishing certain parts to make them darker. if the proof shows a general loss of detail the fault may lie either in the proving of the cut or in the reproduction. if it is in the reproduction it can not be remedied without reengraving. a slight loss of detail may be expected in all half tones, especially in those that are smaller than the copy submitted. . minor changes can be made in photolithographs and chromolithographs, but changes can not be made twice in one place without danger of affecting the printing. it is customary to approve all lithographic proofs subject to the corrections indicated, the printed edition being examined and compared, but if the changes are numerous and radical second proofs may be required. second combined proofs of chromolithographs are very expensive. (see p. .) proof reading illustrations. an author should examine the proofs of his illustrations closely and should compare them carefully with the original drawings. a mere cursory examination may fail to detect errors that have not been caught by the regular proof reader. every correction desired should be clearly indicated with pen and ink in the body of the proof and inclosed in a loop from which a line should be carried to a marginal note or comment, but if the time available is short a pencil may be used. in correcting type matter or lettering (such as that in a geologic legend or explanation) the ordinary proof reader's marks should be used. the author or the person examining the proofs should initial each one at the place indicated by a rubber stamp. proofs should be held only long enough to examine them properly and to compare them with the original illustrations, for a time limit is fixed in each contract for engraving, and if the author holds proofs beyond a reasonable time he causes a delay in the fulfillment of the contract. as the illustrations for many reports contain important data that will be discussed in the text, proofs of illustrations can not be supplied to any applicant without consent from the director's office. general considerations. the following requirements are essential to obtain good original illustrations: . the material selected should be pertinent and expressive; it should have the qualities essential to good illustrations. . the character of the report and the size of the illustrations should be kept clearly in mind. if the report is preliminary or ephemeral the illustrations should be simple and inexpensive. if the report represents the sum of knowledge on the subject treated or the last word on some particular area the illustrations may be more elaborate. the character of a report generally determines the form of publication, which, in turn, determines the size of the pages and the size of the plates and figures. every sketch made should be larger than publication size--preferably twice publication size--whether it is a simple diagram or a base map. . the kind of reproduction that is apparently needed should be fully considered, for it should have some relation to the kind of report. the illustrations for short-lived reports are reproduced by the cheaper processes. those for hurried reports are reproduced by processes that can be worked quickly, but no process should be considered that will not give a clear reproduction of essential details. . clearness of preparation of original matter is invariably essential. an author should not expect the draftsmen or the editors to supply missing links. each original should be complete and should be so made that it can be understood and followed without question. changes made in the finished drawings or on proof sheets are expensive and delay publication. part ii. preparation by draftsmen. general directions. the work of preparing illustrations such as are used in the reports of the geological survey is essentially that of making finished drawings from more or less crude and imperfect material furnished by authors to illustrate certain features or phenomena discussed in their manuscripts. each finished drawing must be so prepared that it can be reproduced in multiple by one of several processes of engraving. the author's sketches and other material are commonly called "originals"; the finished illustrations are known by the engravers as "copy." though most engraver's copy consists of more or less elaborate drawings that are to be reproduced in facsimile by "direct" processes without the interposition of handwork, some of it consists of more roughly prepared copy which is accurate in statement but requires complete manual or "indirect" reproduction. the direct processes in use are zinc etching, half-tone engraving, photolithography, three-color half tone, photogravure, and photogelatin. the manual or indirect processes are wax engraving, wood engraving, engraving on copper and on stone, plain lithography, and chromolithography. these processes are described on pages - . part i of this pamphlet contains some matter that is pertinent to final preparation and should be consulted by draftsmen. to prepare a drawing that will be in every way suitable for reproduction usually requires experience of a kind not acquired in many other kinds of drafting, such as preparing engineers' or architects' drawings, because the drawings themselves or blue prints made directly from them are the things the engineer or the architect desires. drawings prepared for reproduction are generally made larger than publication size, and it is therefore necessary to gage each line, letter, or feature for a definite reduction. engineers' and architects' drawings generally do not require preparation for reproduction by any process, but in preparing illustrations for the reports of the geological survey reproduction must be fully considered at every step, and each drawing must be made according to the requirements of a certain selected process and gaged for a certain reduction. the draftsman should therefore know how to plan each drawing step by step for an engraved cut, a lithograph, a text figure, or a plate, always with a definite result in view. he should be familiar with processes of engraving and should know the special requirements of each process, and he should be able to prepare drawings for any specified reduction in a way to insure good, legible reproduction. the geologic draftsman should read and study such textbooks of geology as those of dana and geikie and should familiarize himself with structural geology, the geologic time divisions, and geologic nomenclature. he should be able to prepare a simple, effective illustration from complicated rough originals and to supply minor missing essential parts or features. to perform his work successfully he must possess mechanical skill and some artistic taste, as well as good eyesight and great patience. instruments. the following list of draftsmen's instruments is practically complete. those which are considered indispensable are marked by asterisks; the others may be used according to individual preference. the same kind of instrument may be duplicated in different sizes according to the variation in the demands of the work. air brush and connections. pens, payzant's, set. beam compass. *pencils, best quality, graded bow pen, drop spring. leads. *bow pen, steel spring. *protractor. bow pencil, steel spring. railroad curves, pearwood, set. *brushes, red sable. railroad pen. china saucers. *railroad pencil. *color box. reading glass. *compass, pen and pencil points. *reducing glass. crayons, assorted colors. *ruling pen. curve rule, adjustable. scale, boxwood, inches long, *dividers, plain. with divisions of millimeters *dividers, proportional. and inches. dividers, steel spring. scales, boxwood, triangular. drawing boards, several sizes. section liner (parallel ruling eraser, glass. device). *eraser, rubber, hard. straightedge, steel, inches. *eraser, rubber, soft. straightedge, steel, inches, *eraser, steel. with divisions for hundredths erasing shield. of an inch and millimeters. *french curves, xylonite. *straightedge, wood, inches. microscope, low power and swivel or curve pen. lenses. thumb tacks. palette knife. tracing point, steel. pantograph. *triangle, °. pens, double-pointed. *triangle, °. *pens, gillott's, nos. , *t square, pearwood, xylonite edge. , . *tweezers, dentist's. pens, k. & e., drawing. no. . classification of material. the draftsman handling the drawings and other original material submitted by the author of a report for its illustration should first group them, as far as possible, into kinds or classes, in order that he may decide how each illustration should be prepared ( ) to express most effectively the author's purpose, ( ) to insure reasonable economy in preparation and in reproduction, and ( ) to meet the requirements of the processes of reproduction selected. all similar illustrations for one publication should be prepared in the same general style. in a series of geologic sections, for example, the same lithologic symbols should be used throughout for the same kinds of rocks. the titles, explanations, and captions of the maps should also agree with one another in general style and in details of workmanship. the draftsman should determine in advance the reduction for each drawing or for each group of drawings, in order that he may use the same size of letters or the same kinds of type for the lettering on a series of drawings that require the same reduction. the reduction should preferably be marked in fractions (as " / off," " / off" or "reduce / ," "reduce / "), and the choice of the same reduction for a group of drawings will not only insure greater uniformity in the drafting and in the reproduction but will permit the drawings to be reproduced more economically, for the engraver can photograph them in groups instead of each one separately. the draftsman should therefore note and consider ( ) the special features shown in the author's originals; ( ) whether or not these features have been plainly indicated and whether the originals are complete; ( ) the size of the printed page of the volume in which the illustrations will appear and the reduction required for each drawing; and ( ) the process by which each drawing should be reproduced. if an original is of doubtful or uncertain interpretation or appears to be incomplete the draftsman should confer with the author of the paper if he is within reach or should bring the matter to the attention of the chief of the branch; otherwise he may waste much time in making the drawing. preparation of maps. projection. the base maps furnished by authors (see pp. - ) are prepared in many different ways and in different degrees of refinement and of crudity, but the work of redrawing them for reproduction involves well-established and generally uniform principles. all maps except those of very extensive areas should be based on a map projection which will show with a minimum of distortion the effect of the curvature of the earth. the polyconic projection (see fig. ) is used for most government maps. in this projection the central meridian is a straight vertical line, and each parallel of latitude is developed independently of the others. the mathematical elements of map projection are given in tables published by the geological survey[ ] and the coast and geodetic survey.[ ] figure , however, illustrates the mechanical or constructional features of the polyconic projection and if used in connection with the published tables will probably be a sufficient guide for projecting a map on any desired scale. [footnote : gannett, s. s., geographic tables and formulas, th ed.: u. s. geol. survey bull. , . see also gannett, henry, manual of topographic methods: u. s. geol. survey bull. , pp. - , .] [footnote : methods and results: tables for the projection of maps and polyconic development; appendix no. , report for ; tables for a polyconic projection of maps, based upon clarke's reference spheroid of ; d ed., .] [illustration: figure .--diagram illustrating method of projecting a map.] in projecting a map first select a convenient measuring scale for setting off the dimensions given in the tables, or if no scale is at hand one may be constructed. measuring scales are made, however, bearing divisions for miles and kilometers and finer subdivisions of to parts. they include the ratios of : , , : , , : , , : , , : , , : , , : , , : , , : , , , and others. on a map drawn on the scale of to , , for example, inch would represent mile; on a map drawn on the scale of to , , , millimeter would represent kilometer, and so on. it will be seen that the use of a scale that shows in ratios, such as those just given, the actual distance on the ground as compared with the unit representing the same distance on the map will reduce the possibility of error. the method of projecting a map, illustrated in the accompanying diagram (fig. ), is as follows: first draw a straight vertical line (a) through the middle of the sheet to represent the central meridian of the map and a line (b) at the lower end of this line exactly at right angles to it to represent the bottom of the map. then set off on the line showing the central meridian the distances between parallels given in table on page of "geographic tables and formulas" (bull. ). it should be noted that the figures in these tables give the distance, in meters and statute miles, of ° on a meridian measured ' each way from a point where the meridian is intersected by a parallel. the exact distances between parallels as measured on the ground are given in the coast and geodetic survey tables, or they may be computed from table of "geographic tables and formulas" by adding the sum of the figures given for any two latitudes ° apart and dividing by . the distance between parallels that are ° apart, as shown in the diagram, may be computed from table of "geographic tables and formulas," as follows: meters. meters. ° of latitude on th parallel = , . / = , . ° of latitude on th parallel = , . ° of latitude on th parallel = , . / = , . --------- true distance from ° to ° latitude = , . the distances given in the diagram were obtained by adding the figures given in the coast and geodetic survey tables, which yield the same results. other tables in bulletin give the true distances in inches on maps of certain standard scales. through the points thus obtained on the central meridian draw lines at right angles to the vertical line. along these horizontal lines lay off the dimensions in the column headed x, table (pp. - ) of "geographic tables and formulas" as required for each individual map--in the diagram every alternate degree. draw vertical lines at these points and set off the distance y in the same table in a similar manner, and the points so found will be the points of intersection of the respective meridians and parallels. figures are given on the diagram for the thirty-fifth parallel only. details of base maps. anyone who attempts to draw a base map must, first of all, know how each feature or part of the map should be represented. most of the conventional symbols for features shown on base maps are well established and should invariably be used; for instance, a line composed of alternate long and short dashes (not dashes and dots) represents a county boundary, and a line or two parallel lines across which short lines are drawn at regular intervals represents a railroad. if he finds that two or more symbols have been widely used to represent the same feature the draftsman should select the one that is best suited to the map in hand. the correct forms of the conventional symbols or features to be used in preparing miscellaneous maps are shown in plate iv, but the size and weight of each line or symbol must depend on the size and character of the map. transferring of copying. tracing. the oldest method of transferring a map or parts of a map or other drawing to another sheet is that of copying it by means of tracing paper. this method, though still used for simple work, has given way to quicker and more effective methods. by one of these methods a piece of thin, fairly smooth paper (not necessarily transparent) is coated with graphite by rubbing over it a soft pencil. when the graphite has been evenly distributed over it, this sheet is laid upon the drawing paper, coated side down, the map or other subject to be copied is laid upon the graphite-coated sheet, and the two outer sheets--the drawing paper and the map--are securely fastened together. by a steel tracing point or very hard pencil the lines and other details of the matter to be copied are then firmly and carefully traced and thus transferred to the clean drawing paper beneath. for maps that show several features in different colors sheets rubbed with blue, orange, brown, or green pencils may be used, one after another, for tracing each set of the features. red should not be used, as it is not easily erased. this method insures distinctive lines for the separate features and prevents the confusion that might result from the use of one color only. exact register of the features shown in the several colors used may be insured by fastening one edge of the drawing to be copied to the drawing paper by mucilage or thumb tacks. the colored sheets may then be slipped in and out without altering the position of the lines or symbols for one set of data with relation to those for the others. in the final preparation of a base map to be engraved and printed in colors--for example, black, blue, and brown--tracings of the three colors appearing on the original base should generally be transferred, as described above, to one sheet of paper and thus worked up into a three-colored map. it is usually unnecessary and undesirable to draw each color on a separate sheet. the preparation of separate drawings may facilitate reproduction, but if they are made on tracing cloth the usual uneven shrinking or stretching of the cloth may produce misregister in the printing; therefore it is safer to make a single drawing, so that the photolithographer can make three negatives and separate the colors by painting out or "opaquing" the colors not wanted on each negative. a map drawn on a single sheet is also less bulky and can therefore be more conveniently handled and compared with proof. if for any reason separate tracings for the different colors to be used on a map are considered desirable they should be made on linen cut from one roll and in the same direction according to the warp and woof. celluloid transferring. in the celluloid method of transferring a map or parts of a map to paper upon which a complete new map is to be drawn the map or part of the map to be copied is photographed to the exact scale of the new drawing and reproduced in graphite on thin sheets of celluloid. the celluloid sheet is then laid face down in the correct position on the drawing paper and firmly rubbed on the back with a steel burnisher, which makes a perfect offset of the map on the paper. after the parts desired are inked over the rest of the graphite print is easily erased with an ordinary rubber. by using this method it is possible to get absolute scale and more satisfactory results than by tracing over a photographic print line for line or by using a pantograph. requisitions for celluloid prints are made on the form used for requesting photolithographic work. sketching by reticulation. if the sheet bearing the design or matter to be copied may be marred without objection it is ruled lightly into pencil squares of equal size. corresponding squares of the same size, larger, or smaller, according to the size of the new drawing, are then ruled on the drawing paper, and the work is sketched square by square. if the original sheet may not be marred the same result can be obtained by drawing the lines on a transparent oversheet. this method is serviceable for enlarging or reducing simple work that includes no great amount of detail; if great precision of detail is required the original should be enlarged or reduced by photography or by the pantograph. the "shadowless drafting table." one of the most useful contrivances that has been made for tracing a drawing on the same scale is called by its manufacturers the "shadowless drafting table." the essential features of this table are a wooden box inclosing strong incandescent lights and bearing a ground-glass top. a drawing placed on the ground glass can be so illuminated as to make its lines conspicuous and readily traceable even through relatively thick paper. the table is particularly useful for tracing sheets upon, which the lines are indistinct and would not be discernible under tracing paper with reflected light. it is also useful in preparing drawings in which certain features must register perfectly over each other. in fact any drawing that does not require enlarging or reducing can be traced with great facility by the use of this drafting table, and it is particularly useful for tracing faint lines on old and poorly preserved prints or drawings. such a table has been installed in the section of illustrations, where it can be used by authors and others. topographic features. relief. the effect of relief is expressed on a map by three methods--by contours, by hachures, and by shading. (see fig. .) the first method does not give pronounced pictorial expression of relief, though it gives correct shape and exact elevation; the others are mow pictorial, but they do not give exact elevation. _contours._--as contoured maps are originally prepared from actual surveys the draftsman should simply follow the copy furnished by the topographer or such original matter as may be given to him for redrawing. if the area mapped is large and the contours are close together the original may be transferred by celluloid tracing (see p. ), or it may be transferred by tracing with graphite-coated paper (see p. ). after the contour lines have been transferred they should be traced in ink, in lines of even thickness, except those that represent certain fixed intervals and are to be numbered, which should be made slightly thicker. (see fig. , a.) in drawing these lines some draftsmen use an ordinary ruling pen, others the swivel pen; but considerable practice is required in the use of either before it can be controlled to follow precisely the penciled lines. still other draftsmen use the shepard pen or an ordinary drawing pen. the swivel pen, if expertly handled, produces a firm and even line. italic numbers should be used to indicate the elevation of a contour and should be placed in an opening in the line, never between lines. where the lines run close together great care should be taken that they do not touch unless the interspaces are so narrow that they must touch and combine. the lines should be firm and even, and if the copy or original map shows that they are uniformly very close together it should be enlarged before the tracing is made in order to give more freedom in drawing; but if the enlarged map is to be much reduced care should be taken to make the lines proportionate to the reduction. a photo-engraving of a map on which the contour lines are drawn very close together is likely to be unsatisfactory because, though the spaces between the lines are reduced in width, the lines themselves may show no corresponding reduction in thickness. [illustration: figure .--methods of expressing relief: (a) by contour lines, (b) by hachures, (c) by shading on stipple board, and (d) by a brush drawing. the four examples given represent the same area. the drawings were made twice the size of the printed cuts.] certain contour lines are commonly accentuated on a map, generally every fourth or fifth line--that is, for a -foot interval every -foot line, for a -foot interval every -foot line, for a -foot interval every -foot line, for a -foot interval every -foot line, and for a -foot interval every -foot line. _hachuring._--the effect of relief can be produced satisfactorily by hachuring but only by a draftsman who has had considerable well-directed practice in that kind of drawing. in a hachured map the light should seem to come from the west or northwest--that is, the darker parts should be on the east or southeast side of an elevation and the lighter parts on the west or northwest the highest elevation should be represented by the darkest shade on the right and by a corresponding high light on the left. the hachuring should begin at the crest of a peak, range, or butte and be worked downward toward the gentler slopes, the lines being drawn farther apart and made thinner until the floor of the valley is reached and the effect of shadow is lost by fewer and lighter lines. on a hachured map that is made from a contoured map somewhat definite differences of elevation may be indicated by the intervals between the strokes, and abrupt changes in slope may be indicated by shorter and heavier lines. the strokes should be disjointed, and they should trend at right angles to the upper margin of a cliff and should radiate from a peak. figure , b, represents satisfactory hachuring. _hill shading._--relief is more easily expressed by shading than by hachuring. (see fig. , c, d.) the draftsman can best express it by this means after he has studied contoured maps or photographs of the region mapped, if they are available, in order that he may obtain an idea of the details of its topography. the special means used to produce hill shading will depend on the character of surface of the paper on which the drawing is to be made, the size of the map, the amount of detail and refinement of execution desired, and the amount of reduction to be made in reproducing the drawing. for maps on which it is desired to show some refinement of drawing and detail, a lithographic or wax crayon can be used on paper which has a grained surface. the draftsman must express relief according to the information he has at hand, whether detailed or general, and must employ methods that accord with the purpose of the map and the mode of reproduction selected. if a shaded relief map is to be prepared for direct reproduction by photolithography and the shading is to be printed in a separate color the base map should be completed first and a light photographic or blue print obtained on which to add the relief in black lithographic crayon, to insure perfect fitting of the relief and the base; or the relief can be prepared on an oversheet--a semitransparent white paper with sufficient "tooth" or grain to cut the shading up into minute dots. the shadowless drafting table (see p. ) is especially useful for this purpose. on this oversheet register marks should be placed at the four comers and at several other points, particularly at the intersection of parallels and meridians. for relief shading on small black and white maps ross's hand-stipple drawing paper may be used. (see p. .) by rubbing a black wax crayon or pencil over the surface of the paper the desired effect is produced in fine dots or in stipple, which may be varied in density of shade at the will of the draftsman. (see fig. , c.) high lights can be produced by scraping away the chalky surface of the paper. a lithographic or wax crayon is the best medium to use on this stipple paper, as on the paper referred to in the preceding paragraph, for the shading produced by it is not so easily smeared as that produced in pastel or by a graphite pencil. the object of using either the rough paper or boss's stipple paper for drawings that are to be reproduced by photo-engraving is to produce a shading that is broken up into dots of varying sizes, which is essential in such reproduction. belief shading for maps can also be made with a brush in flat washes of either india ink or lampblack. such shading should be made only over a blue print or an impression of some kind from the map upon which the shading or relief is to be overprinted. if the relief is expressed on the author's original by contours the general shapes of the relief and the drainage lines can be traced and transferred lightly in blue lines to form a base on which to model the shading and at the same time to make the shading fit the streams. such a drawing can be photographed through a screen and reproduced by half tone (see fig. , d) or mezzotint as a separate plate made to overprint the map in another color. hydrography. _general directions._--the drainage features of a map should be so drawn as to suggest the natural courses of the streams. streams should not be drawn in straight, hard lines, as such lines are decidedly unnatural and produce a crude effect. the course of a river may be straight in general, but it is likely to be somewhat sinuous in detail. if the streams shown on a preliminary map are drawn in a clumsy or characterless fashion they should be redrawn with a freehand effect or made slightly wavy, in order that they may appear more natural. the gradual widening of streams from source to mouth should also be shown in the drawing. on small-scale maps, where the eye can at once see a stream through its full length, this almost imperceptible widening can be expressed by a line of almost uniform weight except for the stretch near the source, where it should grow thinner and taper off. on maps which are to be reproduced directly from drawings in black and white and which are to show both contour lines and drainage the lines representing the streams and other water bodies should generally be drawn freehand and slightly heavier than the contour lines, which should be sharper and more precise. the names of all streams or other bodies of water should be in italic letters, those of the larger streams being lettered in capitals and those of the smaller streams in capitals and lower-case letters. (see "lettering," p. .) _water lining._--the use of water lining on black and white maps should be limited to maps on which the water areas are not readily distinguishable from the land areas. in rough drawings that are to serve only as copy for engravers a flat color may be used for water areas and its conversion into water lines specified. in base maps to be reproduced in three colors a light-blue tint may be used in lieu of water lining, and it can be printed either flat or in a fine ruling transferred to the stone that is to print the drainage. the engraving of water lines is expensive, and the flat blue color should generally be preferred. water lining usually consists of to lines on engraved or large maps, but on small maps and sketch maps the number may be reduced as desired. care should be taken that the lines are as nearly parallel as they can be made freehand and of even weight or thickness. the first three to six lines outside the coast line should be somewhat closer together than those farther out and should conform closely to the coast line, but the spacing between the lines should increase and the lines should become almost imperceptibly less conformable to the coast line as they reach their outer limit, the last three to six being made with the greatest care and refinement. water-lined maps that are to be reproduced by photographic processes should be drawn at least twice publication size. the reduction will bring the lines closer together, and the reproduction will show a more refined effect than could possibly be produced by the most skillful drawing. good examples of water lining, such as are shown on the topographic atlas sheets of the survey, should be studied by draftsmen before they undertake such work. [illustration: u. s. geological survey preparation of illustrations plate iv symbols used on base maps] cultural features. the cultural features represented on a map include "the works of man"--not only cities, towns, buildings, bridges, railroads, and other roads, but state, county, and other boundary lines--in short, all that part of a three-color base map which is shown in black, the engraved plate for the black being called the culture plate. the features named in the list below are the cultural features referred to. (see pl iv for corresponding symbols.) aqueduct mains. aqueduct tunnels. bench marks. boundary lines. boundary monuments. breakwaters. bridges. buildings. cable lines. camps. canal locks. canals. cemeteries. churches. cities. county lines. dams. district lines. ditches. electric power lines. fences. ferries. fords. gas wells. hedges. hospitals. jetties. land-grant lines. land-section lines. levees. mains. mineral monuments. mine tunnels. mines. national forests. national parks. oil tanks. oil wells. open cuts. park boundaries. paths. pits. post offices. precinct lines. prospects. province lines. quarries. quarter-section lines. railroads, steam or electric. ranches. reservation boundaries. reservoirs. roads. ruins. schoolhouses. section comers. section lines. settlements. shafts. streets. telegraph lines. towns. township comers. townships. trails. tramways. triangulation stations. tunnels. villages. water mains. water wells. waterworks. windmills. lettering. general directions. the cultural features are named on maps by letters of two distinct styles--slanting gothic for public works and roman for habitations and civil divisions. the size of the letters used should indicate in a general way the relative importance of the feature or group to which they are applied, but on some maps the county seats, state capitals, and large cities may be distinguished by different symbols. the names of civil divisions are lettered in sizes depending on their relative grade and the size of the area or space in which the names are to appear. the features shown on a topographic map may be broadly separated into four groups and are lettered as follows: civil divisions (countries, states, counties, townships, land grants, reservations, cities, towns, villages, settlements, schools, lodges, ranches, etc.), roman capitals or capitals and lower case. public works (railroads, tunnels, roads, canals, ferries, bridges, fords, dams, mains, mines, forts, trails, etc.), slanting gothic capitals (light) or capitals and lower case. hydrographic features (oceans, seas, gulfs, bays, lakes, ponds, rivers, creeks, brooks, springs, wells, falls, rapids, marshes, glaciers, etc.), italic capitals or capitals and lower case. hypsographic features (mountains, ranges, peaks, plateaus, cliffs, buttes, canyons, valleys, peninsulas, islands, capes, etc.), upright gothic capitals (light) or capitals and lower case. the essential principles of lettering have been described in numerous treatises and are well understood by most draftsmen. the correct form of each letter may be learned from such treatises, but spacing and arrangement are best learned by observation and experience. good lettering will not strongly attract attention, but even slight imperfections of form, spacing, slant, and shading will be quickly detected and criticized. map letterers should note that the name of a place or the number of a symbol should be put to the right of the symbol if possible and a little above or below it--not to the left and directly on a line with it, as tucson=o=, =o=, dallas=o=, carson=o=. names indicating large areas, if written from west to east, should curve with the parallels, and all names should be so lettered that "if they should fall they would fall on their feet." every name should be distinctly legible but not so conspicuous as to subordinate the feature it designates. lines should therefore not be broken in order to make the lettering clear except where there is possible danger that the smaller spaces may be filled up in printing. the lettering on a map should always be so spaced that it will properly fit the area it is intended to designate. in names consisting of two or more words the letters should not be closely spaced if wide spaces are left between the words. in numbers, except those used to indicate elevations on contour lines or elsewhere, thousands should always be set off by commas. draftsmen often draw bad forms for commas, quotation marks, apostrophes, and question marks. the following forms are correct: comma , ; quotation marks "" ; apostrophe ' ; question mark ? . lettering by type. names and short notes printed from type on paper, to be cut out and pasted in proper positions on maps or other drawings, now furnish a large proportion of the lettering on the survey's illustrations. the strips are likely to become detached by the repeated handling of a drawing, however, unless they are securely pasted on. the best results can be obtained by having the type printed on a special brand of "noncurling" gummed paper, from which the lettering is cut in squares or strips, which are dampened and applied to the proper places on the drawing. in handling such strips a pair of dentist's tweezers is useful. when mucilage is applied to printed strips of ordinary paper the moisture causes the paper to warp or curl, often so much as to affect the reproduction of the drawing. this printed lettering is generally used, however, only for headings, titles, notes, and other matter that stands alone; it should not be used for the geographic names in the body of a map unless only a few names are to appear, for the strips of paper bearing the names may obscure parts of the map. the reproduction of this lettering by photo-engraving or photolithography gives results superior to those obtained from hand lettering unless each letter is made with the utmost care, work which is considered a waste of time. [illustration: u. s. geological survey preparation of illustrations plate v reduction sheet used in lettering illustrations. the largest size shows the letters unreduced; the other sizes show the letters reduced as indicated in the margin.] type is used also for printing lettering directly on a drawing exactly in proper position, by a special type holder, somewhat like a self-inking stamp. most of the styles and sizes of type now used on maps in the survey's reports are shown in plate v. if a drawing is to be reduced one-half the smallest type used should be about millimeters in height; if it is to be reduced one-third the smallest type used should be about . millimeters in height; and so on. no letter whose vertical height after reproduction would be less than about millimeter should be used, and the larger lettering should bear a proper relation to the smaller. sheets showing the styles of type in use by the survey, in full size and reduced one-fourth, one-third, two-fifths, one-half, three-fifths, two-thirds, and three-fourths, will be furnished on request. if a drawing is to be reduced one-half, for example, the sheet that has been reduced one-half will show the size of the lettering on the printed plate, so that the draftsman, by referring to the sheet showing the reduction he desires, can select type of a size that will be legible. plate v shows a part of this reduction sheet. abbreviations. the following are the correct forms for abbreviations used on maps and other illustrations: a. arroyo. b. m. bench mark. bdy. boundary. br. branch, bridge. c. cape. can. canal, canyon. cem. cemetery. co. county. cr. creek. e. east. el. elevation. est. estuary. fk. fork. ft. fort, foot. gl. gulch, glacier. hrb. harbor. i. island. is. islands. jc. junction. l. lake. lat. latitude. ldg. landing. l. s. s. life-saving station. l. h. lighthouse. long. longitude. m. p. milepost. m. m. mineral monument. mt. mount. mtn. mountain. mts. mountains. n. north. pen. peninsula. pk. peak. p. o. post office. pt. point. r. range, river. res. reservation, reservoir. r. h. road house. s. south. sd. sound. s. h. schoolhouse. sta. station. str. stream. t. township. tel. telegraph. w. west. words like mount, river, point should not be abbreviated where they form a part of the name of a city or town, as rocky mount, fall river, west point. neither the word nor the abbreviation for railroad or railway should be placed on a map; the chartered name (or initials of the name) and the road symbol are sufficient. names of states and territories should be abbreviated, where abbreviation is necessary, as follows: ala. ga. minn. n. j. tenn. ariz. ill. miss. n. mex. tex. ark. ind. mo. n. y. va. calif. kans. mont. okla. vt. colo. ky. nebr. oreg. wash. conn. la. nev. pa. w. va d. c. mass. n. c. r. i. wis. del. md. n. dak. s. c. wyo. fla. mich. n. h. s. dak. alaska, guam, hawaii, idaho, iowa, maine, ohio, samoa, and utah should be written in full. the abbreviations used on the margins of maps for subdivisions of land should be as follows (note punctuation): t. n., e. w. on large-scale plats the marginal lettering should be as follows: n. / ne. / sec. , t. n., k w.; fractional secs. and , tps. and n., r. w.; nw. / sec. , t, n., r. w. in spelling fractions use half and quarter, not one-half and one-quarter. the abbreviated forms of such names as north fork and south fork should be n. fork and s. fork, not north fk. and south fk. additional abbreviations used on illustrations are as follows: n. for north, ne. for northeast, nne. for north-northeast, etc. capitalize directions affixed to street names, as nw., se. ( f st. nw.). sec. and secs. for section and sections before a number. capitalize only at the beginning of a line or sentence. a. m. and p. m. for antemeridian and postmeridian, as . p. m. lower-case unless in line of caps. & in names of corporations or companies. on survey miscellaneous maps "and" is spelled out in railroad names. b. t. u. for british thermal units. bbl., bbls. for barrel, barrels. bu. for bushel or bushels. c. c. for cubic centimeter. cm. for centimeter. cwt. for hundredweight. dwt. or pwt. for pennyweight oz. for ounce or ounces. etc. (not &c.) for et cetera. ft. for foot or feet. h. m. s. for hours, minutes, and seconds. (use capital h.) in. for inch or inches. kw. for kilowatt or kilowatts. £ s. d. for pounds, shillings, and pence. per cent (omitting period) for per centum. spell out percentage. ser. for series. st. for saint or street u. s. army for united states army, as distinguished from united states of america (u. s. a.). yd., yds. for yard, yards. [illustration: u. s. geological survey preparation of illustrations plate vi -line screen -line screen -line screen -line screen -line screen -line screen half-tone cuts showing effect of several standard screens in the reproduction of the same detail.] the names of certain months may in some places be abbreviated; those of others should invariably be spelled out. the following are the correct forms: jan. apr. july oct. feb. may aug. nov. mar. june sept dec. the abbreviations for number and numbers before figures are no. and nos. the o should never be raised, as in n^o. the abbreviation for mac is mc, not m^c. all periods should be omitted from abbreviations used in the body of a map unless their omission would cause misunderstanding. they are generally unnecessary, and if used on some maps they are likely to be mistaken for symbols representing certain features, such as houses or flowing wells, if either is shown. periods used on drawings that are to be reproduced "direct" or photomechanically should always be slightly exaggerated. names of railroads. the names of railroads may be written in full or abbreviated, in accordance with the kind of map and the space available. on a sketch map in black and white the initial letters are generally sufficient. on a more detailed map, if there is room enough, the names may be spelled out. as already stated, neither the words "railroad" and "railway" nor the abbreviations r. r. and ry. should be used on a map. make-up of maps. forms for certain features. the proper forms for certain features of maps, such as the borders, titles, explanations, bar scales, captions, arrows indicating true north and magnetic declination, source, and authorship, are shown in plate vii. note particularly the style and position of the marginal matter. border. a finished map border is used or omitted according to the kind of map prepared. diagrammatic maps and maps on which no parallels and meridians appear do not need finished borders. on a map that shows complete areal geologic or other coloring, such as a map in a survey geologic folio, the border lines tend to destroy the simple effect of the whole map. on a map that is not completely colored and on all very large maps borders are really necessary. if borders are used, however, the space between the neat line and the outer line of the border should be only sufficient to provide proper space for the numbers showing latitude and longitude or township and range. a simple rule[ ] for determining the width of this space is as follows: divide the sum of the dimensions of the map by and find the square root of the quotient, which will represent the width of the border in sixteenths of an inch. example: map is by inches; ( + )/ = ; square root of = ; width of border = / inch. [footnote : worked out by martin solem, of the u. s. geological survey.] the numbers showing latitude and longitude should be in shaded arabic numerals and those showing township and range in gothic. the symbols for degree, minute, and second should not be crowded. on a map that has no added border lines the numbers should be in hair-line gothic. title. the title of a map should be in roman letters and if placed at the lower margin should generally be arranged in two lines, unless it is short. if it forms two or more lines the lines should be well balanced. the first line should describe the position of the area; the second line should state the purpose of the map, as map of butte and vicinity, montana showing location of mines and prospects. a title placed inside the border of a map should be arranged in a series of lines, generally beginning with "map of" or "geologic map of." and the line showing the dominant part of the title should be emphasized by larger lettering, thus: =map of= the vicinity of butte montana showing location of mines and prospects. the name of the author or compiler of a map or of the person supplying the geologic or other data shown on it may be placed either beneath the title or in the lower right corner, just below the border line, and the names of the topographers or the source of the base should be stated in the lower left corner, just below the border line. if the title is placed inside the border all notes giving credit for any part or features of the map may be placed beneath the title or scale. (see pi. vii.) [illustration: u. s. geological survey preparation of illustrations plate vii details of the make-up of a geologic map] explanation. the symbols, patterns, or colors used on a map should be given in a series of rectangles or "boxes," accompanied by explanatory terms in the form shown in plate vii, headed "explanation." if the explanation is small a convenient place for it on some maps may be found within the neat lines. if no space is available there, or if it is so large that there is not room to place it there without obscuring other details, it may be placed either vertically along the right margin, as shown in plate vii, or horizontally under the title. a geologic explanation should preferably be arranged vertically, as in plate vii, so as to show the relative age of the formations by the positions of the boxes. this explanation should be carefully worked out in pencil by the draftsman and approved by the committee on geologic names before it is drawn in ink, in order to save time in making corrections. in lettering the explanation roman letters or type should be used for the titles under the boxes and italic of smaller size for the subtitles or descriptive detail, which should be inclosed in parentheses. the names of geologic periods and systems should be in gothic capitals, the names of series or groups should be in italic lower case, and the limit of each period, system, or group should be indicated by braces. the general style and arrangement shown in the survey's geologic folios should be followed, and this and the arrangement of other matter is shown in plate vii. care should be taken not to crowd the explanation, and if corrections are necessary they should be so made that each line of the matter in which they appear will be properly spaced. the explanation for a map that is to be engraved or to be reproduced by lithography need only be sketched in to show general style and arrangement. the engraver or the lithographer will supply such matter in proper form according to specifications. for direct reproduction, however, as by photolithography or zinc etching, the lettering must either be carefully drawn with pen or printed from type on slips, which are pasted on the drawing. graphic scales for maps. a bar scale for miles or feet should be given on every map, and if the map is of international interest the metric scale should be given just beneath the scale of miles or feet. the accepted designs for these scales are shown in figure . the scale should be accompanied by any necessary statement pertaining to the base map, such as "contour interval feet," "datum is mean sea level." the fractional scale ( / , , for example) should be given on all except the more simple kinds of maps, and the date of publication should also appear just below the scale or scales. the single-line bar scale should be used only on small or simple maps. the length of the bar scale must depend on the size of the map and the space available. those shown in figure were made over blue prints from scales used by the survey. to make a bar scale for a map of unknown scale that shows only a single meridian and parallel, or for a map on which no meridians or parallels are shown, first ascertain the distance between two points shown on the map by reference to other authentic maps. if, for example, the distance between two such points is . miles draw a horizontal line (_a_ in fig. ) representing this distance on the map, and at its end, at right angles to it, draw another line (_b_) actually measuring . units of any convenient denomination. draw a straight line (c) diagonally between the ends of lines _a_ and _b_. then set off on line _b_ any convenient number of the units selected, say or , and project from the points set off lines exactly parallel with line _c_ to line _a_. the distance and the number of the units thus marked on line a will indicate the number of miles covered by that distance on the map, as shown in figure . [illustration: figure .--designs for bar scales.] [illustration: figure .--method of making a bar scale for a map of unknown scale.] [illustration: u. s. geological survey preparation of illustrations plate viii patterns used to show distinctions between areas on black and white maps contrasts may be increased by varying the direction and spacing of lines] symbols. symbols should be drawn with as much care as letters, though to a critic they may not appear so bad as poor lettering unless he finds them glaringly large or so small that he can discover or identify them only with difficulty. the size of a symbol must depend on its importance on the map bearing it. on a map that shows numerous mines, for instance, the crossed hammers or the symbols for shafts should be not only visible but conspicuous. the draftsman who is to make such a map must know beforehand how much his drawing will be reduced in reproduction and must make the symbols in proportion to the reduction. the symbols shown in plate ii (p. ) should be used in all the survey's illustrations where they are appropriate. areal patterns for black and white maps. the conventional patterns used on a map to distinguish separate areas, chiefly geologic, are shown in plate viii. the patterns shown represent the proper combinations of lines, dots, and other forms and should be spaced openly or closely according to the size of the area covered, the contrast needed between areas, and the general clearness and effect desired. if a map is to show both small and large areas dense or closely spaced patterns should generally be used for the smaller areas, even if they may be required for some fairly large areas representing the same formation or condition. on the other hand, open patterns should be used for large areas. again, it may be necessary to make certain areas more conspicuous than others, and this effect can be best produced by drawing the lines closer together rather than by making them heavier, unless the area covered is small or unless a closely spaced similar pattern has been or will be used elsewhere on the map. heavy-line patterns or bars are not desirable. the lines forming a pattern should generally be drawn at an angle of ° to the sides of the map; they should be drawn vertically or horizontally only in small areas or in areas not crossed by meridians or parallels or by other lines running in the same direction. the lines should preferably run across the long axis of an area, not parallel to it, and the predominating trend or general direction of the areas of one geologic formation on a map should decide the direction of the lines for all areas of that formation on the same map, even if the rule must be violated on some of the minor areas. an effort should always be made to produce a pattern that is subordinate in strength to the main lines of the base map on which it is drawn. in black and white maps, as in colored maps, unlike patterns should be placed next to each other. if they are so placed it may not be necessary to rule the lines on two adjacent areas in opposite directions to produce needed distinctions. a section liner or other ruling device should be used in drawing line patterns in order to produce uniformly even spacing. the application of six of these conventional patterns to a base map is shown in figure . [illustration: figure .--map bearing six areal line patterns.] standard colors for geologic maps. the standard series of colors for systems of sedimentary rocks is shown on the maps in the survey's geologic folios but is subject to modifications for use on maps in other survey reports. each system is represented by a different color, and if there are two or more formations in one system they are generally distinguished by using different patterns composed of straight parallel lines in the same color. the patterns for subaerial deposits (chiefly quaternary) are composed of dots or circles, or combinations of both, and may be printed in any color, but the color most often used is yellow or ochraceous orange. no specific colors are prescribed for igneous rocks, but if only a few areas are shown red or pink is preferred. the colors used for igneous rocks are generally more brilliant and purer than those used for sedimentary rocks. for small areas they are used "solid"; for large areas they are reduced in tone by the use of a suitable cross-line pattern or "reticle." metamorphic rocks are represented by short dashes irregularly placed. these dashes may be in black or in color over a ground tint or over an uncolored area, or they may be in white on a ground tint or pattern. the standard colors used for the sedimentary series covering the systems recognized by the geological survey are: quaternary (q), ochraceous orange; tertiary (t), _yellow ocher_ and _isabella color_; cretaceous (k), _olive-green_ or _rainette-green_; jurassic (j), _blue-green_ or _niagara-green_; triassic (tr), _light peacock-blue_ or _bluish gray-green_; carboniferous (c), _blue_ or _columibia-blue_; devonian (d), _gray-purple_ or _heliotrope-gray_; silurian (s), _purple_ or _argyle-purple_; ordovician ( ), _red-purple_ or _rocellin-purple_; cambrian (-c), _brick-red_ or _etruscan red_; algonkian (a), _terra cotta_ or _onion-skin pink_; archean (ar), _gray-brown_ or _drab_.[ ] [footnote : names printed in italic are from "color standards and nomenclature," by robert ridgway.] reduction of enlargement of maps. the following is the simplest and most accurate method of marking the reduction or enlargement of a map to a selected scale: measure the distance between the extreme meridians along one of the parallels. (see fig. .) convert this distance into miles by multiplying the number of degrees it covers (say ) by the number of miles in a degree. a degree on the forty-third parallel, for example, is . miles,[ ] which multiplied by equals . miles. then draw a line on the margin of the map, outside the border, the exact length of the degrees, and just below this line draw another line representing the same number of miles ( . ) on the scale to which the map is to be reduced or enlarged. then mark to reduce or enlarge the upper line to the lower line, as shown in figure . a long line will reduce error and give greater accuracy than a short one, and therefore as great a distance should be set off as possible. the number of miles represented by both lines and the fractional scale to which it is to be reduced should be stated on the drawing, for permanent record. [footnote : see u. s. geol. survey bull. , p. . .] maps that will bear reduction without affecting the clearness of the details they show may be reduced to fit the book in which they are to appear, regardless of definite scale. the reduction for such maps is best marked in fractions, as " / off," " / off," " / off." if the size needed is not exactly represented by these fractions it should be indicated in inches, as "reduce this line to - / inches," or "reduce to - / inches in width." [illustration: figure .--diagram showing method of marking maps for reduction or enlargement (for record).] diagrams. in preparing a diagram a draftsman should endeavor to make its parts and relations perfectly clear to the reader. he should study the drawing or material furnished by the author until he fully understands it and should endeavor to reproduce it simply and legibly. any lettering that may be needed should generally be in plain upright or slanting gothic type (see pl. ix), or it may be in roman. a diagram should generally be drawn on bristol board or on blue-lined section paper and should be marked for reduction to the minimum size. it should bear no title, as the title will be set up in type by the printer. sections. the sections used in geologic reports are of two widely different kinds. one shows only the broader relations of parts; the other shows details of structure as well as relations. one is diagrammatic; the other is more realistic and graphic. the draftsman should prepare all sections strictly according to the copy supplied by the author but should use proper symbols and make a more finished drawing. the various kinds of sections, most of them geologic, are described on pages - , and the conventions used to express lithologic character are shown in plate iii. [illustration: u. s. geological survey preparation of illustrations plate viii diagrams and curves.] detailed drawings of this kind, though entirely conventional, can be so prepared as to give a satisfactory expression of nature. the draftsman should study well-prepared sections in geological survey reports and should learn the details of folding and faulting from textbooks. he should first ascertain whether or not the vertical scale in the original section has been unduly exaggerated, and if so he should confer with the author with a view to reducing the exaggeration as much as possible. he should submit to the author all questions as to doubtful points, as well as all suggestions for improvement in expression, before he makes any changes, and he should make corrections only on the author's approval. a seeming inaccuracy in an author's drawing may be a faithful representation of natural conditions. for example, a formation that seems to be omitted by inadvertence in drawing may really "pinch out" at a point represented in the section. (see a on fig. .) [illustration: figure .--structure section showing method of determining the secession of folds.] penciled lines corresponding to those shown by dots in figure should be carefully added in redrawing a roughly sketched section that shows complex folding. an original indefinite sketch that shows complicated structure affords opportunities for error in preparing the new drawing, and omissions may be detected by following the formations as they would be continued above and below the section, as shown by the dotted lines in the figure. plans and cross sections of mines. plans of mines, like diagrams, should not be elaborate, and their lettering should be plain and legible, yet it should not be so conspicuous as to obscure other details. gothic letters should generally be used, but some plans require different styles of lettering, especially for geographic or other names that should be coordinate with those on maps or other illustrations in the book. unless there are good reasons, however, for varying the styles of lettering, plain gothic capitals, or capitals and lower-case letters, either upright or slanting, should be used. abbreviations for the numbers of levels should generally be given thus: d level, th level, -foot level, etc., or the shorter terms may be spelled out, as third level, sixth level. the same general scheme of lettering should be used on all plans and cross sections that are to appear in one publication or in one series of similar papers. the reduction of such drawings to the minimum scale consistent with clearness is always advisable. drawings of specimens of rocks and fossils. methods used. drawings of specimens or other objects were once made with brush and pencil or with pen and ink, by means of measurements taken with dividers or by viewing the specimen through a camera lucida. each of these methods is still used, but by using the camera lucida in sketching: the outlines and details more accurate proportions and relations can be produced, whether the object is to be enlarged or reduced, than by any other means except photography. brush and pencil drawings. in all drawings or photographs of specimens, except photomicrographs of thin sections, the light should appear to come from the upper left quarter. a disregard of the well-established rule that the direction of illumination should be uniform throughout a series of drawings would cause confusion or uncertainty in the interpretation of the relief shown in them. reynolds's three-ply and four-ply bristol board affords a satisfactory surface for brush and pencil drawings. its surface is smooth and hard and, being free from coating of any kind, permits satisfactory erasures without great injury; its color is pure whits; and it is durable. boss's relief hand-stipple paper is also well adapted to many kinds of brush drawings as well as to its primary use for producing stippled effects. very delicate gradations of color or light and shade can be produced on its surface with brush and lampblack or with india ink, and high lights can be made by scraping off the chalky surface. the draftsman who is preparing brush and pencil drawings should have first of all a knowledge of the principles of light and shade, of reflected light, and (for drawing specimens) of shadow perspective. he should also have delicacy of touch and ability to see and interpret form and to reproduce the soft blending of light and shade shown in a good photograph. he should be provided with pencils equal in quality to the koh-i-noor b, f, h, and h; the best quality of red sable brushes of the sizes of winsor & newton's nos. , , and ; the best quality of stick india ink; a cake or pan of lampblack; and a porcelain saucer or slab. in drawings of fossils and of some other specimens a combination of pencil and brush work produces satisfactory results and tends to increase speed. the gloss produced by penciling, however, is objectionable and should be obviated by a preponderance of brush work. stick india ink is the best pigment to use in delicate wash drawings, and lampblack is preferable for large work on which the softer tones of the shading are not so important and for drawings that are to be considerably reduced when engraved. gouache (an opaque mixture of chinese white and lampblack) may also be used, but it is best suited for large work. in making corrections on brush drawings the parts to be corrected should be carefully washed out with a small short-cropped brush and water and still further cleaned by using a rubber eraser over an erasing shield or an opening cut in a piece of celluloid. erasures should not be made on delicate work with a knife or a sand rubber, as either will injure the surface and affect reproduction. in measuring a specimen with dividers the draftsman should be careful not to injure the specimen or to puncture the paper on which he is preparing the drawing. pen drawings. a draftsman who is preparing drawings of specimens with pen and ink should have a good assortment of pens equal to gillott's nos. , , and , liquid waterproof ink equal to that manufactured by higgins, good pencils, hard and soft rubber erasures, plain dividers, and reynolds's bristol board. a glass eraser is also useful. good pen drawings of specimens are much more difficult to make than brush drawings. they can be prepared only by a draftsman who has had some artistic training and experience in pen work. few draftsmen can prepare pen drawings that faithfully represent both the detail and the texture of specimens; the shading on many such drawings confuses and destroys both detail and texture. the pencil sketch over which a pen drawing of a specimen should be made must be prepared in much the same manner as the sketch for a brush drawing, though the outlines need not be so delicate. this sketch is generally made on bristol board. the pen work should begin with the outlines and should then be carried to the details, and finally to the shading, whether in lines or stipple. the texture of a specimen is the best key to the proper shading. if the specimen is decidedly granular, stippling is appropriate; if it is smooth or polished, finely drawn parallel lines, varied in spacing and character according to depth of shade and texture, are preferable. erasures can be made with a hard-rubber eraser, other parts being protected by a shield, or with a very sharp knife or a glass eraser, and the parts erased can be resurfaced with an agate burnisher. retouching photographs of specimens. photographs of specimens, particularly fossils that have been coated to destroy local color, should be printed on velox paper, in a tone somewhat lighter than that of ordinary photographs. the details and relief should, however, be strong enough to enable the draftsman to see them clearly, so that by retouching them and strengthening the shadows and high lights he can make them sufficiently strong for reproduction. this he can do by a combination of pencil and brush work, the pencil being used sparingly because the gloss produced by the graphite is likely to affect reproduction. a no. winsor & newton's red sable brush and lampblack are preferable for the greater part of this work, and a h and a h pencil for the fine details and as a possible aid in producing the finer gradations of shading. the details should be retouched or strengthened under a reading glass to insure accuracy; the broader effects can be best produced without the aid of a magnifier. erasures on photographs of specimens should be made very carefully with a hard rubber that is free from sand, and the parts not to be disturbed should be protected with a shield. high lights may be added by carefully scraping or rubbing the surface of the paper. landscape drawings from poor photographs. a poor photograph or one that has become injured and can not be retouched for direct reproduction can be utilized by making from it, as described below, a pen drawing or a brush or crayon drawing, which will be almost photographically correct. pen drawings made over photographs. a pen and ink drawing may be made over a blue print or a bromide print (preferably a blue print) and the photographic image then bleached out. the blue print should be larger than publication size and should not be so dark that the draftsman can not see his lines. if the negative is available a bromide enlargement can be obtained; otherwise the picture should be rephotographed in larger size, preferably twice publication size. the enlargement will give the draftsman greater freedom in drawing details and will make his work appear finer and better in the reduced illustration. if the photographic print is of a subject requiring the use of instruments it should be securely fastened to a drawing board, square with the board, so that any horizontal and vertical lines in it may be ruled by the use of a =t= square and triangle. for specimen or landscape work it need not be fastened. for bleaching blue prints a saturated solution of oxalate of potassium (k c o + h o) has been used with good results. for bleaching bromide prints cyanide of potassium (kcn) to which a few drops or flakes of iodine have been added should be used. neither kind of print should be bleached until the drawing has been completely finished in every detail, because bleaching loosens the fibers of the paper, so that the ink of any added lines is likely to spread. the print should be placed in a hard-rubber pan, the bleaching solution poured on it, and the pan rocked until the image disappears. the print should then be carefully removed, thoroughly washed in running water, placed between clean white blotters to dry, and finally mounted on cardboard. for temporary, hurried work on drawings that are not to be retained for future use the blue print may be mounted first and bleached by pouring the bleaching fluid over the mounted print. brush drawings from poor photographs. brush drawings may be made directly from photographs by working over an enlarged print with gouache, or by making a pencil tracing and sketch of the photograph and working it up with lampblack or india ink. the photograph should be larger than publication size to permit greater freedom and breadth in drawing details. the larger size will also afford a more refined and better engraving when reduced. if lampblack or india ink is used and the subject is small, bristol board is recommended, but if the photograph is larger than, say, by inches, whatman's hot-pressed double elephant or similar paper, laid down with thumb tacks, will prove satisfactory. if gouache is used over a print a preliminary drawing is of course unnecessary, but the photograph should be an unglazed print of a size that will require considerable reduction, and the finished drawing should be protected by an oversheet. if lampblack or india ink and not gouache is used the photograph should be traced and a fairly complete pencil sketch should be made before the brush is used. plates i, iv, _a_, v, _b_, and vii, _b_, monograph , were made from gouache drawings. plates iii, _a_, vii, _a_, x, xi, xii, xiii, xx, xxviii, and xxx, in the same publication, were made from lampblack or india-ink wash drawings. the originals can be examined at any time. outdoor sketches. the art of sketching from nature is one in which few but professional artists excel. not many geologists are able to make sketches from nature that are suitable for direct reproduction. an artistic draftsman should be able to redraw the geologist's sketches, however, in their true perspective and relations, with the skill necessary to make them satisfactory illustrations. in most crude outdoor sketches the important features are usually shown with sufficient clearness to follow. if they are not the draftsman should ascertain what those features are and prepare the new drawing in such a way as to display them properly. the new drawing should be made with pen and ink, generally for reduction to a text figure, which is the most appropriate form for such an illustration. in all sketches of this kind the lines should be drawn in such a way as to produce natural effects and at the same time to make good printing plates. good examples of pen and ink sketches of this class can be found in monograph , already referred to, and in the seventh annual report, especially plates xxviii and xxxviii; ninth annual report, plates xliii and xliv; tenth annual report, plates xiv and xix and figure ; eleventh annual report, plates xv, xxvii, xxxv, lii, and liv and figures , , , , , and . drawings of crystals. a crystal should generally be drawn in outline with straight lines. the invisible rear side of a crystal, if shown, should be represented by dashed lines. the outer boundary line of a crystal should be slightly heavier than the inside lines, which should all be of the same weight. striations should be shown by straight lines; broken or uneven surfaces by irregular lines. a twinning line, if an intersection edge, should be solid; if not an intersection edge it should be broken into dashes. italic, greek, german, and old english letters are used to mark crystal faces. all faces of a given form should be marked by the same letter but may be differentiated, if necessary, by primes or numerals, thus: m, m', m'', m''', m{'v}. "leaders" should be short full lines, or, if these are likely to be confusing, they should be dashes. numbers may be used in place of letters for specific purposes. letters indicating twin faces are underscored; a second twin is doubly underscored or overscored, thus: m_, m=, m¯. twin units may be differentiated by the use of roman numerals. retouching photographs. an author, of course, selects his photographs to illustrate some special features; he does not always consider their fitness for reproduction. photographs that are blurred or out of focus, those in which the shadows are too black or lack transparency, and those which have local defects, such as bad skies or spots, must be worked over to make them suitable for reproduction. in order to remedy these defects and produce natural results the draftsman doing work of this sort should be able to see and interpret nature properly and to supply natural effects in a manner corresponding with those produced photographically. he should be sufficiently expert with the brush and pencil and in handling an air brush to duplicate the delicate and soft tones in the photograph, and he should know how the pigments he uses will "take" when the subject is reproduced. the retoucher should have access to an air brush and should provide himself with a jar of photo white or blanc d'argent and a color box containing indian red, crimson lake, yellow ocher, lampblack, and ultramarine--colors with which he can duplicate those shown in any photograph. he should also have the best grade of red sable brushes, ranging in size from no. to no. , a stack of porcelain saucers, and a jar of oxgall. by mixing the colors to match exactly the shades of a photograph and using a red sable brush he can strengthen details, "spot out" flaws, and remove imperfections, except those in skies or other large, flat areas, for which he must use an air brush. the air brush has become a necessary adjunct to a retoucher's outfit. smooth, even gradations of flat tones can not be successfully applied to photographs without it, and it is therefore indispensable, especially for retouching skies and covering other large areas. before retouching a photograph the draftsman should mix in a saucer a tint that will match the color of the part that is to be retouched and should try this tint and note its effect after it has dried and change it, if necessary, until it matches the color exactly. if he is to retouch a number of photographs that have the same local color he may with advantage make up enough of the tint for the entire lot, thoroughly mixing it and seeing that it is not too thin. in making this tint he should use only pigments of the best grade, and if he finds that the chinese or other white he is using does not photograph well, or that it does not hold its color, he should discard it at once and use another brand. photographs that are to be retouched should be large enough to permit sufficient reduction to soften the effects of retouching. in order to eliminate the lines of junction between two or more photographs that are joined together to form a panorama some adjustment or fitting of details by retouching is generally required before the group is rephotographed to obtain a new print of the whole on one piece of paper. as it is often desirable to increase the width of such an illustration the photographer should be instructed to print the photograph on a strip of paper that is wider than the negative, so that, if necessary, the retouching may be carried above or below the new print to add depth to the illustration. panoramas may also be drawn from photographs with either pen or brush in the manner described on pages - . part iii. processes of reproducing illustrations. methods employed. the preliminary work in producing illustrations includes the preparation, from originals submitted by authors, of drawings and other kinds of "copy" in such a way that the copy can be reproduced in multiple by printing. several processes are used for preparing plates for printing illustrations, and each has its peculiar features of excellence. one process may render fine details with facility but may fail in uniformity in large editions; another may be cheap and effective on the whole but may not reproduce fine details; and still another may give fine color or tone effects but may be too expensive. therefore a knowledge of the varied uses and results and of the cost of the several processes of reproduction and, on the other hand, of the kinds of originals that are best suited for reproduction by any one of the processes is essential to effectiveness and economy in planning, preparing, and reproducing an illustration. the following condensed descriptions of processes are intended mainly to aid in determining the kind of copy that is appropriate for each process and the kind and quality of reproduction to be expected, so that only the principal operations or stages in each process are described. wood engraving, which was used in making printing plates for many of the illustrations in the early publications of the geological survey, is described here only to compare that laborious and "indirect" method of engraving cuts with the more modern kinds of relief engraving. in it gave way to photo-engraving. photo-engraving. general features the term "photo-engraving" is applied to processes by which a black and white line drawing, photograph, or like original is reproduced in relief on a metal plate from which prints may be made on an ordinary printing press, in distinction from processes that print from flat or relatively flat surfaces, such as the lithographic and photogelatin processes. the photo-engraving processes that are most generally used are those called "zinc etching" and "half-tone engraving." these processes depend on the discovery that gelatin or similar organic material, if treated with potassium or ammonium bichromate and exposed to the action of light, is made insoluble in water. if a metal plate coated with bichromatized gelatin or albumen is exposed to light under a negative the parts acted upon by light become insoluble and those not acted upon remain unchanged and may be washed away so as to expose the metal, which is then etched with acid in order to give relief to the unexposed parts and make of them a printing surface. zinc etching. zinc etching is adapted to the direct reproduction of a pen and ink drawing composed of lines, dots, or solid black areas. on the finished metal plate these lines, dots, and solid areas form the printing surface, and the spaces between them, which have been etched away, represent the white or blank parts of the picture. the process is cheap and is almost universally used for reproducing small drawings designed for text illustrations. it is also well adapted to the reproduction of maps and diagrams measuring in print not more than about by inches. one of the chief advantages of this and of all other direct (photographic) processes of engraving is that they reproduce a drawing in facsimile, whereas the "personal equation" must enter into all engravings made by an indirect method--that is, by hand--such as wood engraving, wax engraving, and engraving on stone or copper, which make it necessary to compare every detail of the proof with every detail of the drawing before the engraving can be approved. the pen drawing to be reproduced, which should preferably be considerably larger than the completed engraving, is first photographed to the proper size or scale on an ordinary negative film. the film is then stripped from the negative and reversed in order that the etched plate may print the design as in the original and that the film may be grouped with other films on one large glass and all printed at the same time. the negative (whether a single film or several) is then placed in a specially constructed printing frame in contact under pressure with a sensitized zinc plate and exposed to light. after the zinc plate has been removed from the printing frame (in the dark room) the plate is rolled with printer's transfer ink, which resists acid, and placed in a shallow tray containing water, in which it is rocked for several minutes, and then taken out and rubbed gently with cotton. the parts of the coating of the plate that were acted on by light have become insoluble and will therefore be unaffected by the water, but the parts of the coating not acted on by light and therefore not hardened will be removed by the washing, which will expose the metal and leave the parts acted on by light--the picture--in black lines, dots, etc. the plate is then dusted with "topping powder," a resinous substance which adheres only to the parts carrying the ink. the plate is then heated so that the resin and the ink that remain fuse together and form, when cooled, a resistant surface which will not be affected by the acid to be used later in etching the unprotected parts of the plate. the plate is now ready for a preliminary etching in a fluid consisting of water and a few drops of nitric acid. it is placed in a tray, rocked gently for a short time, and then removed, washed well in running water, drained, and dried with gentle heat. "dragon's blood," a resinous powder that resists the action of acid, is next applied to the plate, in order to protect the sides of the lines and the dots from the acid, and the plate is then heated just sufficiently to melt the powder and units it with the ink. a small quantity of nitric acid is now added to the etching bath, and the plate is subjected to its first thorough biting or etching. it is then removed from the bath, washed under a tap, carefully wiped with a damp rag, and dried with gentle heat. the plate is thus treated three or more times until it is etched deep enough to insure satisfactory printing, and it is then ready for finishing, which consists of deepening the larger open spaces between the lines with a routing machine and of cutting away with hand gravers lines that are improperly connected or that are so close together that they will not print separately. the routing machine is provided with a cutting tool mounted on a revolving spindle that projects downward into the engraved plate, which is securely fastened. the movement of the arm that holds the cutter is universal and can be controlled with great precision. the plate is then "proved" that is, a proof is taken from it on paper and if the proof is satisfactory the plate is nailed to a block of wood on which it will be "type high" ( . inch), for printing. most drawings for zinc etching are made with a pen in black ink and consist of lines, dots, or masses of black, but drawings may also be prepared by using some medium that will produce a fine stipple, such as a black crayon on rough paper or ross's stipple paper. (see p. .) the drawing should be one and one-half to two or three times as large as the printed illustration, for it is impossible to obtain a satisfactory reproduction of a pen and ink drawing without some reduction. if the drawing has not been reduced the lines appear heavier in the reproduction than in the drawing, and imperfections thus become more noticeable; if it has been properly reduced, imperfections are diminished and the lines and dots become thinner and finer than those in the drawing. in making a drawing that is to be reduced the draftsman can also space his lines farther apart and work out his details more easily. an author should carefully examine and approve the finished drawings, which can, of course, be greatly altered, if necessary, before they are engraved; but similar corrections can not be made on proof sheets of zinc cuts, which should not be marked for alterations except by eliminating parts. minor changes can be made in such a cut by an expert "finisher," but if the cut is small it is generally cheaper to correct the drawing and have a new cut made. zinc etchings cost about to cents a square inch, the cost being varied according to a standard scale which is based upon the ascertained cost of reproduction. the minimum charge for a single cut is $ . copper etching in relief. copper etching, which produces a line cut in relief, requires the same kind of copy that is most often marked for zinc etching and is used to obtain deeper etching and a more permanent cut. it is said to produce better printing plates than those etched on zinc and is used largely for reproducing script lettering and other fine work. as copper plates will hold up longer in printing than zinc, a cut etched on copper may not need to be electrotyped. the chemical part of the process is practically the same as that employed for etching half-tone plates, described under the next heading. the cost of etching on copper is considerably greater than the cost of etching on zinc. this process is not often used in reproducing illustrations for publications of the geological survey. half-tone engraving. the half-tone process is, in name at least, familiar to almost everyone who has had any connection with the making of books, whether as author, editor, illustrator, or printer. the invention of a photomechanical process of reproducing a line drawing to make a metal plate that could be printed along with type on an ordinary printing press naturally led to attempts to reproduce similarly a photograph. it was known that the intermediate shades between white and black in a photograph--the half tones--can be reproduced on an ordinary printing press only by breaking them up into dots or lines that will form a good printing surface and that by their variation in size or density will give for each shade the effect of a uniform tone. in the half-tone process this effect is produced by photographing the picture or object through a screen. the half-tone screen consists of two plates of glass, on each of which lines running generally at an angle of ° to the sides of the plate have been engraved, cemented together so that the lines cross at right angles. the lines, which are minute grooves filled with an opaque black pigment, thus appear as a series of black crossed lines on a white ground. the screen is placed in the camera in front of the negative. screens are made that show from lines to an inch for the coarser newspaper illustrations to lines or more to the inch for fine book work. the screens used for magazine illustrations generally show to lines. those used for survey publications show to lines, and for reproducing delicate drawings and photographs of fossils screens bearing lines to the inch are sometimes specified; but these finer screens require the use of highly super-coated papers, some of them made of cheap fiber and not known to be permanent. for a half tone that is to be printed in the text a -line or a -line screen is specified. (see pl. vi, p. .) the method of etching a half-tone plate does not differ greatly from that used in zinc etching, and there are several kinds of half-tone plates, though most of them are etched on copper, not on zinc, those etched on zinc being used principally for newspaper illustrations. the half-tone screen is used also in other processes to obtain a negative. when a half-tone negative hag been made the film is stripped from the glass plate and reversed, as in the zinc-etching process, though some half-tone engravers use a mirror box or prism by which the picture is so disposed on the negative that it does not need stripping and reversing. a perfectly flat, clean, and highly polished copper plate, generally large enough to accommodate several such films, is then coated with a sensitive film according to one of several formulas, all based on the fact that gelatin or some similar body, if sensitized with certain chromic salts, becomes hardened and insoluble in water on exposure to light. this plate is then placed in the printing frame in contact, under pressure, with the glass negative plate and is exposed to light in the usual manner. the copper plate is then removed from the frame in the dark room and made ready for etching. for etching half-tone plates on copper a saturated solution of perchloride of iron is used instead of the solution of nitric acid used for zinc etching. the time of etching ranges from about to minutes, according to the strength of the solution. one etching is generally sufficient, but it may be necessary to give the plate another "biting" if it has not been etched deep enough, or to re-etch it in order to strengthen contrasts. if, for instance, the sky in a half-tone plate shows too dark or is uneven in tint it can be made lighter or more even by re-etching. on the other hand, if certain features on a plate are too light they can be darkened by burnishing--rubbing the surface with a highly polished steel burnisher under just sufficient pressure to flatten slightly the fine points that form the printing surface of the plate. when the plate leaves the hands of the etcher it is turned over to the finisher, who with a graver removes spots or any other imperfections that may appear on it. sometimes a roulette is used to lighten parts, and other tools are used for special purposes. after a plate that shows two or more pictures has been etched and finished it is divided by sawing them apart. each one is then put into a beveling machine, where its edges are trimmed and the usual border is made, if it is desired. the separate plates are then ready to be proved and mounted on blocks of wood which make them type high, ready for printing. the half-tone process is used almost exclusively for reproducing photographs and wash drawings, though it will produce a facsimile of any kind of copy, such as impressions from type, old manuscripts, or typewriting, but a shade composed of minute black dots will appear over the entire print and there will be no absolutely whits areas unless they are produced by routing the plate or cutting out the high lights. (see p. .) the reproduction of an ordinary outdoor photograph requires very little handwork, except for re-etching, burnishing, and cutting the borders. in the reproduction of copy that is made up of separate parts, such as groups of photographs of specimens that are to appear on a white ground, the half-tone "tint"--or more properly shade--between and around the several figures must be removed and numbers must be added. this operation requires two negatives--one half tone and one line--and produces what is called a "combination" plate. therefore the difference in the cost of making a half-tone cut from a single photograph of a landscape and from a cut made from "copy" of the same size consisting of a number of small photographs or drawings, to which numbers or letters are added, is considerable (about per cent greater) and depends upon the amount of additional work involved. routing, when needed, must be done with extreme care lest the edges of a figure be marred, and this work requires skill that can be gained only by experience. copy for the half-tone process should be as nearly perfect as possible. only the best photographs should be selected. prints on semimat velox and glossy haloid papers are regarded as the best photographic copy for reproduction. every part of the photograph or drawing should be absolutely clean. if any part that should be pure white becomes soiled or stained the defects will be reproduced. if a photograph needs retouching it should be retouched with great care and just sufficiently to correct defects and to bring out or strengthen the important details. in many photographs the skies may be "muddy" or uneven in tone, and this defect can be corrected by the use of an air brush, the only medium that will produce an almost even tone. as already stated, half-tone plates can be improved by re-etching and tooling, but tooling tends to destroy the effects of nature and produces an artificial appearance in the print. one who is preparing wash drawings for reproduction by the half-tone process should remember that brush marks and other inequalities of tone will be reproduced with as much fidelity as other details. such drawings should therefore be made two or three times larger than the engraved cut in order to subdue all unnatural effects and to soften the general tones. line drawings are not generally suitable copy for the half-tone process, but it is occasionally desirable to use that process instead of zinc etching for reproducing a line drawing that has been inexpertly prepared if the cost of redrawing would more than offset the difference in cost between zinc etching and the more expensive half-tone process. in reproducing a pen drawing by half tone the lines become softened and represent the details and shading only; but the pen drawing may be further developed by brush work. examples of this type of reproduction are plates v, _a_, vi, _a_, and xv, figure , and other illustrations in survey monograph . vignetting, which consists of a skillful grading off of the edges of a picture, as well as extensive tooling or hand engraving, is often employed for artistic effect but should be specified only for exceptional illustrations. the plates made for the survey are either "square trimmed" or the ground tint is entirely omitted or routed away; they are not usually tooled or vignetted. half-tone cuts etched on copper cost to cents a square inch, the cost being varied according to a standard scale based on the ascertained cost of reproduction. those that require a screen finer than lines cost per cent additional. the minimum charge for a single cut is $ . half tones etched on zinc ( -line screen or coarser) cost per cent less than those etched on copper. three-color half-tone process. the three-color process is practically an adaptation of the half-tone process to color printing based on the theory that all colors or hues in nature can be reproduced by combinations of three colors of the spectrum--red, blue, and yellow. the process differs from the ordinary half-tone process particularly in the use of color filters in making the negatives and in the character of screens and diaphragms used. this process, like all others, is worked somewhat differently in different establishments. in what is called the indirect method, the one most commonly used, twelve photographic operations are necessary to produce one illustration, or the three plates or cuts from which one illustration is to be reproduced by printing. these twelve operations produce three chromatic negatives, each representing one color; three transparencies or positives, made from the chromatic negatives; three half-tone negatives, made from the positives; and finally three contact prints, made on sensitized metal plates. in what is called the direct method the half-tone screen is placed in front of the photographic plate so that it becomes also a half-tone negative from which a print is made on a sensitized metal plate. thus the photographic operations in the direct method are reduced to six, but the interference to the passage of light offered by the half-tone screen and by the prism used to reverse the image on the negative lengthens the time of exposure. unfortunately, no pigments have been found that can reproduce in purity the colors of the spectrum, and to this fact is due the failure of the process to reproduce exactly all the colors, tints, and shades of an original. when a drawing in black on white paper is photographed only the white paper affects the negative film. the transparent parts of the developed negative thus represent the black, and the opaque parts, which have been acted upon by light, represent the whits. theoretically, when a chromatic negative is made for the yellow plate a purple-violet filter cuts out all the yellow and allows the red and blue rays to affect the plate; when a negative is made for the blue plate an orange filter similarly cuts out the blue and allows the yellow and red rays to affect the plate; and when a negative is made for the red plate a green filter cuts out the red and permits the blue and yellow rays to affect the plate. these color filters, which are usually made of transparent stained gelatin, are generally placed in front of the lens. when printing plates like those used in the half-tone process have been made from the three negatives and the plates have been inked with yellow, blue, and red ink, respectively, a combined impression from them will produce a close approximation of the subject photographed. the colored inks often used are light yellow, peacock or prussian blue, and bright, transparent crimson. the ordinary half-tone screen, which bears lines cut at an angle of ° to the sides of the plate, is rectangular, but the screens used for three-color work are made circular in order that they may be turned in the camera to make the lines intersect at other angles, the angles being varied to avoid producing an undesirable pattern or a moire effect. turning the screen also prevents the exact coincidence or superposition of the red, blue, and yellow dots, which would produce black. in other respects the screens do not differ essentially from those used in ordinary half-tone work. as special experience is necessary in printing three-color plates the engraver generally delivers the printed illustrations to the purchaser instead of the plates, which he furnishes for other kinds of relief printing. the copy for this process may consist of anything in color, such as specimens, objects, paintings, or properly colored photographs. the process does not usually reproduce all the colors and tints of an original with equal exactness and is not used by the survey for work that demands precise reproduction of color, but it is satisfactory for reproducing most colored drawings, colored photographs of specimens, or the specimens themselves if they show individual variations in color. as the process is entirely photomechanical it gives more scientific accuracy in detail than chromolithography, in which there is much hand work, and it is much less expensive. if the colors shown in proofs are not satisfactory they can be modified. the four-color process, in which four color plates are used, gives a closer approximation of true color values than the three-color process, and at a comparatively small increase of cost. the additional color used is generally a neutral gray or black. wax engraving (the cerotype process). the wax or cerotype process does not require finished drawings and is especially suitable for making text illustrations and small maps, although it may be used also for large work. for this process blue prints, pencil sketches, old prints, or rough copy of any kind may be submitted--that is, it is not necessary to furnish carefully prepared drawings in black ink, as it would be for photo-engraving, for the wax engraver will reproduce in proper form any illustration in which the copy and the instructions show what is wanted, just as an experienced draftsman will make a good drawing from the rough original furnished by an author. full and clear instructions should always be given, however, as to the size of the cut wanted and what it is to show. in this process a polished copper plate is coated with a film consisting of beeswax, a whitening medium, and other ingredients, and the coating, which varies in thickness according to the nature of the copy, is sensitized as in the ordinary photographic processes. the map or other design to be engraved is first photographed to publication size and a contact print is made on the wax coating from the negative. the lines and other parts of the photographed image are then traced or cut through the wax to the copper plate with steel tools and straightened or perfected by the engraver, but the lettering is set in printer's type, which is pressed into the wax until it also touches the metal plate. after the work of cutting through the wax has been completed the larger open spaces between the lines are "built up" by the addition of wax to give greater depth to the plate, so that the wax plate thus built up corresponds to an electrotype mold. the plate is then dusted with powdered graphite and suspended in a solution containing copper, where by electrolytic action a copper shell is formed over its surface. when this shell is sufficiently thick it is removed from the solution and reinforced on the back with metal, and proofs are taken from it. if the proofs are satisfactory the plate is blocked type-high. wax-engraved plates may be used for printing colored maps or diagrams, in which variations of tint are produced by various kinds of machine rulings. the effect of some of the colors thus produced is almost a "flat" tint, in which a pattern can be detected only by close scrutiny. some color work is printed from a wax base plate in combination with half-tone color plates. the price of a wax engraving depends entirely on the size of the cut, the amount of work involved, and the character of the original copy, but it should not exceed very much the cost of a carefully prepared pen drawing plus the cost of a zinc etching made from it. cuts engraved by the wax process, like zinc and half-tone plates, are delivered to the purchaser. if colored work is ordered, however, the printed sheets, not the cuts, are delivered. wood engraving. wood engraving was once the universal method of producing cuts for illustrations that were designed to be printed on an ordinary press. it is said to be the oldest of all methods of engraving illustrations. the engraving is made on a block of boxwood, a very dense, hard wood of a light-yellow color. the block is cut type-high across the grain, and the engraving surface is made perfectly smooth by nibbing it with pumice or other stone. when a cut is to be larger than or inches square the wood block is made up of pieces securely dovetailed or joined together to prevent splitting and warping. a woodcut is not used for printing but is electrotyped and the electrotype is used in the press. originally the smoothed surface of the wood block was coated with prepared chalk or chinese whits, and on this coating a finished drawing was made with a brush and pencil by an illustrator. according to more recent practice the surface of the wood is covered with a sensitized coating, on which the drawing or design to be engraved is photographed. the engraver then, with various kinds of gravers and other tools, cuts out the parts of the picture that are to be represented by white paper and leaves the lines, dots, and black areas as a printing surface, thus translating the shades and tints of the picture into a system of lines and dots which exactly duplicate, in effect, the details and tones of the original design. in order to produce a line effect of an area in which the tone is intermediate between whits and black the engraver must space his lines so that one-half the area will remain as printing surface and the other half as white spaces, and he must give character and direction to his lines, so that, if he is skillful, he can reproduce not only the delicate tones but the texture and details of the original picture. many wood engravers became noted for their artistic rendering of magazine illustrations, of famous paintings, and of other works of art. the survey began to abandon this method of engraving in , when the sixth annual report was in press, substituting for it the cheaper photomechanical processes, zinc etching and half-tone engraving, and entirely abandoned its use in . many good examples of wood engraving may be found in the early monographs and annual reports of the geological survey. monograph contains numerous examples. photogelatin processes. bichromatized gelatin is used in several photomechanical processes of reproducing illustrations, but in the photogelatin processes the gelatin not only receives the image by exposure to light through a negative but becomes a printing surface on a plate from which prints are made somewhat as in lithography. the several photogelatin processes are much the same as the original collotype process and are best known by the names collotype, heliotype, albertype, artotype, and the german name lichtdruck. in working these processes a thick plate of glass, after certain preliminary treatment, is coated with sensitized gelatin. the plate is then placed in a drying room or oven having a temperature of ° f., baked until it is thoroughly dry, and allowed to cool gradually. the subject to be reproduced is then photographed in the usual manner, and unless a prism or mirror box has been used the negative is stripped and reversed in order to make the print reproduce the original in proper position. from the negative a contact print is made on the gelatin-coated plate, the parts or molecules of gelatin being hardened in proportion to the amount of light that affects them. after the contact print has been made the gelatin plate is thoroughly washed in cold water, in order to dissolve and wash out the bichromate and stop any further action of light on the plate, and is then thoroughly dried. before prints are made from the gelatin-coated plate water is flowed on it and penetrates different parts of the gelatin according to their hardness. the darkest parts of the picture will correspond to the hardest and densest parts of the gelatin, which will not absorb water; the lighter parts will take up more water. the surface water is then removed with a rubber straight edge and an absorbent roller and the plate is ready for inking. the ink, being greasy, has no affinity for water, and when it is rolled over the plate it adheres only to the dry parts of the gelatin, and in the press is carried to the paper in all the lights and shades of the illustration. the plate is kept moist in printing. the paper used for printing from photogelatin plates must be free from chemicals that will affect the gelatin. a nearly pure rag paper is generally used. the photogelatin process is well adapted to the reproduction of paleontologic drawings, wash drawings, photographs, photomicrographs, works of art, old manuscripts--in fact, any kind of subject in which the reproduction of delicate lights and shades is essential. if properly manipulated it has distinct advantages over the half-tone process in that it can reproduce details and light and shade without showing the effect of a screen and without the use of coated paper. excellent reproductions by the heliotype process are also made in color by first printing the design in a neutral tone and superposing appropriate transparent colors on this print, somewhat as in chromolithography, so that the colors softly blend with the shaded groundwork. reproductions made by the photogelatin process are more expensive than those made by the half-tone process, for the prints are generally made on better paper and are printed with greater care. they give no screen effect and are perhaps unrivaled by prints obtained by any other process except photogravure, in which the image is printed from a metal plate that has been sensitized, exposed under a reversed negative, and etched. changes can not be made on photogelatin plates except by making over the corrected parts. all retouching must be done on the originals or on the negatives made from then. lithography. original process. the general term "lithography" is sometimes used to indicate not only the original process so named, said to have been invented by senefelder, but chromolithography, photolithography, and engraving on stone, as well as engraving on copper as a means of supplying matter to be transferred to and printed from a lithographic stone. senefelder discovered that limestone will absorb either grease or water, and that neither one will penetrate a part of the surface previously affected by the other. he found that if a design is drawn on limestone with a greasy crayon and the stone afterward properly prepared with a solution of nitric acid and gum, greasy ink will adhere only to the parts that are covered with the crayon, and that the stone will give off an impression of the design. lithographic stone is described as a fine, compact, homogeneous limestone, which may be either a pure carbonate of lime or dolomitic--that is, it may contain magnesium. although limestone is one of the most common rocks, limestone of a quality suitable for use in lithography is found at only a few localities.[ ] there are two general classes of lithographic stone, known to the trade as "blue" or hard stone and "yellow" or soft stone. the blue stone is adapted for engraving and to the better grade of fine-line printing; the yellow stone is rated as somewhat inferior. [footnote : kubel, s. j., lithographic stone: u. s. geol. survey mineral resources, , pp. - , .] in the original process, which may here be termed plain lithography, two methods are employed in putting on stone the design to be reproduced. in one the subject or picture to be reproduced is drawn on the printing stone either with a lithographic crayon or with a pen dipped in lithographic ink or "tusche," which is oily or fatty, like the crayon. in the other method the drawing is made on transfer paper and transferred to the stone. in drawing on stone it is necessary to reverse the design, so that all lettering must be drawn backward. in doing this the artist often uses a mirror to aid him. if the drawing is made on transfer paper the design and the lettering are copied as in the original--not reversed. before a drawing is made on stone a stone of the quality suited to the particular design in hand is selected. the stone is then ground and polished, and if the drawing is to be made with crayon it is "grained" according to the special requirements of the subject. if the drawing is to be made with a pen and is to consist of "line work" the stone is polished. the first step is to obtain on the stone an outline or "faint" of the design. there are several ways to do this. by one method a tracing of the design is made, a sheet of thin paper covered with red chalk is laid face downward on the stone, the tracing is laid face downward over it, and the design is again traced in red-chalk lines on the stone. the method described is simple, but there are others that are more complicated and that are particularly applicable to the reproduction of photographs and other illustrations. crayon work is often used in combination with pen and ink, stipple, and brush work. this method of drawing on stone is used also for preparing color stones in the process of chromolithography, in which there are many added details of manipulation. after the drawing has been made on the stone or transferred to it the stone is "gummed"--that is, it is covered with a solution of gum arabic and nitric acid--and dried. the stone is then dampened with water and carefully rolled with lithographic ink, which adheres to the pen or crayon work and is repelled elsewhere. it is then "rubbed" over with powdered rosin and talcum, which adheres to the ink and further protects the drawing from the effects of the etching fluid, which is next to be applied to the stone. this fluid consists of a per cent solution of gum arabic to which to per cent of nitric acid has been added, the degree of acidity being varied according to the subject and the hardness of the stone. the fluid is applied with a brush or sponge and is left on the stone just long enough to decompose slightly the carbonate of lime on its surface and, after washing, to leave the design or drawing in very slight relief. the stone is again gummed and dried, and the design is "washed out" or brought out by removing the surface gum with a wet sponge and applying to the stone a rag sprinkled with turpentine and charged with printing ink. these operations wash away the tusche and the crayon that have been decomposed by the acid and expose the design faintly in white at first, but it gradually grows darker as it becomes charged with printing ink from the rag. the stone is next "rolled up" or inked. the slightly moistened surface repels the ink and the design takes it up, so that when the stone is run through the press the design is carried to the paper. lithographic prints from stones prepared in this way are made on a flat-bed press. the stone is carried forward to print and on its return is dampened and inked, an operation slower than that of rotary printing. corrections and changes are made on the stone by carefully scraping or polishing away the parts to be corrected and making the changes with a crayon or pen, but the design can not ordinarily be corrected twice in the same place, as the scraping or polishing removes a part of the surface of the stone and thus lessens the pressure at that place, and the impression there may be imperfect or may completely fail. this form of lithography is seldom used for survey illustrations but was formerly much used and is well adapted to the reproduction of drawings of fossils, particularly of remains of dinosaurs and other types of large extinct animals. examples may be seen in monographs and and in other early reports of the geological survey. the drawings for these illustrations were made directly on stone. a drawing made on one stone may be transferred in duplicate or in any desired number to another stone, or to a properly grained sheet of zinc and aluminum, from which impressions may be printed on a lithographic press. both these metals are also used for lithographic printing on rotary presses, the zinc or aluminum plate being bent and secured around a cylinder which rotates continuously in one direction. as one impression is made at each revolution of the cylinder the printing is rapid; but the best printing from a metal plate is inferior to the best printing from a lithographic stone. photolithography. photolithography, like other lithographic processes, has been improved greatly during the last few years--not particularly in results but in methods--by the introduction of metal plates, the rubber blanket offset, the ben day films, and many mechanical and chemical devices, so that a brief description of it will not explain the process except in a most general way. as photolithography is a direct process and is relatively cheap it is the one most used for reproducing large maps and other line drawings that have been carefully prepared. zinc and aluminum plates are now much used in photolithography, for a direct contact photographic print can be made on them, they can be printed flat or bent for use on a rotary press, and they can be stored for future use more economically than stones. there are two somewhat distinct methods of producing photolithographs. in both the ordinary photographic methods are used, but it is often necessary to "cut" or trace parts of the negative in order to open up lines and other features that are not sharp or well defined, so that the negative will print them sharp and clear. if the copy to be reproduced shows three colors, three negatives are made, one for each color, and the parts to be shown by each are preserved by "opaquing" or painting out all other parts. by the older method the negative thus perfected is placed in a printing frame in contact, under pressure, with sensitized transfer paper and is exposed to light. the printing frame is then carried to the dark room and the paper is removed from the frame and its surface covered with transfer ink. the paper is then laid face upward on water and soaked for several minutes, after which it is placed in the same position upon a slab of stone or metal and thoroughly washed with water. this washing removes the ink and the sensitive film from the parts that were unaffected by the action of light (the parts corresponding to the white paper in the design), but the ink still adheres to the lines of the design in the precise sharpness and clearness of the negative. the design is now ready to be transferred to the printing stone or zinc plate. the sheet is again slightly dampened between moist blotters and laid face downward in its correct position on a prepared stone or zinc plate, which is then pulled through a press under heavy pressure. the paper is then removed from the stone or plate, to which it has carried the design. from this point the gumming, etching, and other operations are practically the same as those used in ordinary lithography. the bichromate-gelatin transfer process described above has been replaced in the survey by a more satisfactory one, which insures absolute scale and reproduces the finest line drawings perfectly without thickening the lines or without distortion. in this process, which is known as the planographic process, a photographic negative of the "copy" is placed in a vacuum printing frame in contact with a zinc or aluminum plate that has been sensitized with a bichromate-albumen solution and exposed in front of an arc lamp. after proper exposure the plate is removed from the frame, inked over, and placed under water. the parts not hardened by the action of light (the unexposed parts) are then rubbed away with cotton, and the plate is chemically etched, gummed over, and dried. the plate is then ready to be printed from in a lithographic press. if a large map is to be reproduced it is photographed in parts, and contact prints are made on zinc plates. from these plates transfers are pulled and the parts are assembled and laid down in proper position on a stone or an aluminum plate, which is then prepared for printing. a drawing that is to be reproduced by photolithography should be made on pure-white paper in lines, dots, or black masses with black waterproof ink. it should be one and one-half to two or three times the size of the finished print. photolithography is particularly adapted to the reproduction of maps, plans, and other large drawings. within certain limitations, lines may be changed and details may be added after proofs have been submitted. the process is ordinarily used for reproducing illustrations in one color (black), but it is used also for printing in more than one color, generally over a black outline base, each color being printed from a separate stone, as in chromolithography. offset printing. in the offset process the design is "offset" from a lithographic plate or stone to a rubber blanket on a cylinder, from which it is printed. by thus obtaining an impression from an elastic surface the finest details can be printed on rough, uncoated paper, which can not be used in other processes, which can be folded without danger of breaking, and which is more durable than coated paper. plates ii, iii, iv, vii, and viii in this pamphlet were printed by this process. chromolithography. the chromolithographic process, by which illustrations are printed in color from stone, is used in survey publications principally for reproducing geologic maps, but it is sometimes used for reproducing colored drawings of specimens. there are several kinds of color printing from stones. one produces a picture by superimposing colors that combine and overlap without definite outlines and thus reproduce the softly blended colors of the original. another reproduces the original by printing colors within definite outlines on a "base" which has been previously printed in black. the first kind is used by the survey for reproducing colored drawings of specimens. the second is followed in reproducing geologic maps. as each color must be printed from a separate stone and properly fitted with respect to the others a tracing from the original is made of the precise outlines of each color; or, if the design is to be reduced, a tracing is made over a properly reduced photographic print. this tracing can be made on specially prepared tracing paper or on a sheet of transparent gelatin or celluloid, which is laid over the copy and on which all the outlines and overlaps of the various colors are scratched with a steel point. the scratches thus made on the celluloid are filled with red chalk or like substance, and rubbed in with cotton, and by reversing the sheet and rubbing it the chalk lines are deposited on as many stones as are needed to produce the colors of the original design, each stone bearing all the outlines of the design. sometimes all the outlines are engraved on what is called a key stone and an impression from it is laid down on each of the color stones. the parts on each stone that are to have one color are then inked in or engraved, and at the same time guide marks are indicated, so that in the composite print from the stones each color will fit its proper place. this fitting is called "register" and is an important part of printing, for each stone must be adjusted to a nicety while on the press in order to make each impression fit the others exactly. the process was originally manipulated entirely by hand, but photography has now replaced much of the handwork and has given rise to several methods by which the same kinds of subjects are reproduced in radically different ways. tints are sometimes produced by the half-tone and other screens and by machine ruling, and printer's type is used almost exclusively for titles and other matter that was formerly engraved or drawn on the stone. in reproducing a geologic map the base may be engraved on stone or on copper or it may be photo-lithographed. by either process the map may be transferred to the printing stone. the color stones for geologic maps are prepared by hand, but the geologic patterns, which are printed in colors, are engraved separately on plates, from which impressions are pulled when needed and transferred to their proper places on the printing stones in the shapes required according to the "key" design. the lighter, more transparent colors are generally printed first, and often twelve or more colors and many distinctive patterns are used to produce a geologic map. when proofs of such a map are pulled each stone must be taken up and carefully adjusted on the press, so that the work of proving maps that are printed from a considerable number of color stones is laborious and expensive. it is therefore customary to approve first combined proofs conditionally--that is, subject to the corrections and changes indicated on the proofs--and to hold the lithographer responsible for any failure to make the corrections. this process is the most expensive one used for reproducing illustrations. changes may be indicated on proofs, but changes can not be made on a stone twice in the same place without danger of affecting the printing or making it necessary to retransfer the parts affected. all changes are expensive because a slight modification at one point may involve corresponding changes on a number of stones, each of which must be taken up, corrected, and proved to insure the exact coincidence of the parts affected. it is often less expensive to retransfer the entire job than to make extensive changes on the original stones. engraving on stone and on copper. engraving on stone is distinctly lithographic, but engraving on copper is sometimes included among lithographic processes because the work produced by it is usually printed from stone and thus becomes lithographic. in other respects engraving on copper is not a lithographic process. roughly prepared maps and any rough line copy that is accurate in statement and clear as to intent are appropriate for both methods of engraving, but drawings that are expertly prepared are more suitable for reproduction by photolithography. in engraving on stone the lines of a design are scratched on the blackened surface of a stone with a steel-pointed tool; in engraving on copper the lines are cut with a graver on a sheet or plate of copper, the matter to be engraved being first shown on the plate by what is called the photo-tracing process, which was devised in the geological survey. there is, however, no great or essential difference in the printed results of the two processes, but most lithographers employ only stone engravers. a stone on which a design is to be engraved is ground and polished according to the kind of work to be engraved, is coated with a thin solution of gum arable and allowed to dry, and is then washed until the superficial gum is removed while the surface pores remain filled. as the lines made by the engraver must be visible the stone is blackened with a pigment composed of lampblack and gum or is covered evenly with red chalk or venetian red. it is then ready to receive the design to be engraved. if the design is a map which is to show culture, streams, and surface contours, and each of these sets of features is to be printed in a separate color, impressions of the work to be engraved must be placed on three stones. one method of doing this is to make a scratch tracing of the original drawing on a sheet of transparent gelatin or celluloid in the manner employed in chromolithography, except that a dry pigment, generally chrome-yellow, is used to fill the scratch lines instead of red chalk or venetian red. from this tracing a "faint" or imprint of all the details of the three separate features of the map is made on each of the three stones, and the engraver then cuts on each stone only the lines and other features, including ample register marks, that are to be printed in one color, the imprint made from the tracing making it possible to engrave each set of features in its exact position relative to the other two. by another method the matter to be engraved is photographed directly on the stone. the engraving is done with a steel needle inserted in a small wooden cylinder, an instrument resembling an ordinary lead pencil. the size and shape of the needles used are varied according to the requirements of the matter to be engraved. with this instrument the lines and lettering are lightly scratched into the stone through the dark coating and show as light lines. the points of some of the needles are fine; those of others are v-shaped; and some have spoon-shaped points, for use in thickening lines and shading letters. all features are engraved in reverse. after the engraving is completed the stones are prepared for printing by wiping off all the superficial color and filling the engraved lines with a greasy ink--generally a thin printing ink--which is rubbed into the lines with a soft rag. impressions are then pulled on transfer paper and transferred to three printing stones for use in printing the three colors, the register marks enabling the pressman to fit each color exactly in its proper place. in all lithographic processes the titles and other marginal lettering can be and usually are transferred from type impressions to the printing stones. it is therefore unnecessary to letter such matter carefully on an original drawing that is made for lithographic reproduction, for appropriate faces of type will give better printed results than hand lettering. corrections can not be made on a stone or copper engraving as readily as on a drawing. if a stone engraver makes an error or if a change is required after his engraving is finished, the parts to be corrected must be scraped off and a new ground laid before the correction can be made. sometimes he will engrave the parts corrected on another part of the original stone and transfer it to the printing stone. corrections are made on copper plates by "hammering up" the plate from beneath, polishing off a new surface, and reengraving the part to be corrected. appendix. the matter given in this appendix is much used in making geologic maps and other illustrations. the greek alphabet and the groups of signs presented are given chiefly to show the correct formation of each letter and sign. miscellaneous tables. _length of ° of longitude measured along given parallels from the equator to the poles._ [from u. s. coast and geodetic survey report for , appendix .] parallel of statute | parallel of statute | parallel of statute latitude. miles. | latitude. miles. | latitude. miles. ----------------------+-----------------------+---------------------- . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | . | . . | | _length of ° of latitude measured along a meridian at given parallels._ [parallel given is in center of the degree whose length is stated.] parallel of statute latitude. miles. ---------------------- . . . . . . . . . . metric system and equivalents. [the units of linear measure most commonly used are millimeters (mm.), centimeters (cm.), decimeters (dm.), meters (m.), and kilometers (km.), m. = dm.; dm. = cm.; cm. = mm.; km. = , meters = . mile; m. = . inches = . feet.] meters. | inches. || meters. | feet. || kilometers. | miles. ----------+-------------++---------+-----------++-------------+--------- | . || | . || | . | . || | . || | . | . || | . || | . | . || | . || | . | . || | . || | . | . || | . || | . | . || | . || | . | . || | . || | . | . || | . || | . inches. | centimeters.|| feet. | meters. || miles. | kilometers. ----------+-------------++---------+-----------++-----------+------------ | . || | . || | . | . || | . || | . | . || | . || | . | . || | . || | . | . || | . || | . | . || | . || | . | . || | . || | . | . || | . || | . | . || | . || | . the "vara," used in texas, is equivalent to - / inches and is computed as representing . feet. _geologic eras, periods, systems, epochs, and series._ era. period or system. epoch or series. { { recent. { quaternary. { pleistocene (replaces "glacial"). cenozoic. { { { pliocene. { tertiary. { miocene. { { oligocene. { { eocene. { { upper (gulf may be used { { provincially). { cretaceous. { lower (comanche and shasta may be { { used provincially). { { { upper. mesozoic. { jurassic. { middle. { { lower. { { { upper. { triassic. { middle. { { lower. { { permian. { { pennsylvanian (replaces "upper { carboniferous. { carboniferous"). { { mississippian (replaces "lower { { carboniferous"). { { { upper. { devonian. { middle. { { lower. { paleozoic. { silurian. { { { upper (cincinnatian may be used { { provincially). { ordovician. { middle (mohawkian may be used { { provincially). { { lower. { { { saratogan (or upper cambrian). { cambrian. { acadian (or middle cambrian). { { waucoban (or lower cambrian). { algonkian. }pre-cambrian. proterozoic. { archean. } _chemical elements and symbols._ element. symbol. element. symbol. element. symbol. aluminum al holmium ho rhodium rh antimony sb hydrogen h rubidium rb argon al indium in ruthenium ru arsenic as iodine i samarium sa barium ba iridium ir scandium sc bismuth bi iron fe selenium se boron b krypton kr silicon si bromine br lanthanum la silver ag cadmium cd lead pb sodium na cesium cs lithium li strontium sr calcium ca lutecium lu sulphur s carbon c magnesium mg tantalum ta cerium ce manganese mn tellurium te chlorine cl mercury hg terbium tb chromium cr molybdenum mo thallium tl cobalt co neodymium nd thorium th columbium c neon ne thulium tm copper cu nickel ni tin sn dysprosium dy niton nt titanium ti erbium er nitrogen n tungsten w europium eu osmium os uranium u fluorine f oxygen o vanadium v gadolinium gd palladium pd xenon xe gallium ga phosphorus p ytterbium germanium ge platinum pt (neoytterbium) yb glucinum gl potassium k yttrium y gold au praseodymium pr zinc zn helium he radium ra zirconium zr _greek alphabet._ caps. lower-case. greek name. english sound. [greek: a] [greek: a] alpha. a. [greek: b] [greek: b] beta. b. [greek: g] [greek: g] gamma. g. [greek: d] [greek: d] delta. d. [greek: e] [greek: e] epsilon. e short. [greek: z] [greek: z] zeta. z. [greek: h] [greek: h] eta. e long. [greek: th] [greek: th] theta. th. [greek: i] [greek: i] iota. i. [greek: k] [greek: k] kappa. k. [greek: l] [greek: l] lambda. l. [greek: m] [greek: m] mu. m. [greek: n] [greek: n] nu. n. [greek: x] [greek: x] xi. x. [greek: o] [greek: o] omicron. o short. [greek: p] [greek: p] pi. p. [greek: r] [greek: r] rho. r. [greek: s] [greek: s] sigma. s. [greek: t] [greek: t] tau. t. [greek: u] [greek: u] upsilon. u. [greek: f] [greek: f] phi. f. [greek: ch] [greek: ch] chi. ch. [greek: ps] [greek: ps] psi. ps. [greek: om] [greek: om] omega. o long. _roman numerals._ i | ix | lxx | d ii | x | lxxx | dc iii | xix | xc | dcc iv | xx | c | dccc v | xxx | cl | cm vi | xl | cc | m vii | l | ccc | md viii | lx | cd | mcm mathematical signs. + plus. ~ difference - minus. integration. Ã� multiplied by. equivalence. ÷ divided by. : ratio. = equality. geometrical proportion. ± plus or minus. -: difference, excess. square. therefore. rectangle. because. triangle. infinity. circle. varies as. angle. radical. right angle. ° degree. or > greater than. ' minute. or < less than. " second. perpendicular. names of rocks. the following list was prepared in the geologic branch for the use of geologic draftsmen to enable them to select appropriate symbols for rocks that may be referred to in preliminary drawings by name only. for sedimentary rocks dots and circles, parallel lines, and broken or dotted lines are used; for metamorphic rocks short dashes arranged without definite patterns; and for igneous rocks patterns composed of short dashes, triangles, rhombs, crosses, and cross lines. all these patterns are shown in plate iii. _sedimentary material._ [including residual, detrital, eolian, glacial, organic, and chemically precipitated material.] agglomerate. ironstone (also igneous). alabaster. itacolumite. alluvium. kame. alum shale. kaolin. anhydrite. laterite. apron (alluvial). lignite. argillite. limestone. arkose. limonite. asphalt. loess. bench gravel. marble (also metamorphic). bentonite. marl. boulder clay. metaxite. brea. morainal deposit. breccia. mudstone. brownstone. novaculite. burrstone. peat. calcarenite. pelite. calc sinter. phosphate rock. caliche. phosphorite. catlinite. phthanite. chalk. psammites. chert. psephites. clay. puddingstone. coal. pyroclastic material. conglomerate. quartzite (also metamorphic). coprolite. reddle. coquina. rock salt. detritus. rock stream. diatomaceous earth. rubble. diluvium. salt. dolomite. sand. drift. sandstone. fan (alluvial). selenite. fanglomerate. shale. flagstone. silt. flint. slate (also metamorphic). freestone. soil. fuller's earth. stalactite. geyserite. stalagmite. gravel. talc. graywacke. talus. greensand. till. grit. travertine. gumbo. tripoli. gypsum. tufa (=chemically deposited lime). hardpan. tuff (=igneous fragments). hematite. wacke. infusorial earth. wash. _metamorphic material._ adinole. hornstone. amphibolite. itabirite. andalusite schist (?). kinzigite. apo (rhyolite), etc. knotenschiefer. argillite. knotty schists. augen gneiss (also igneous). luxulianite (igneous?). biotite schist. marble. calc schist. meta (diabase), etc. cataclastic. mica schist. chlorite schist mylonite. clay slate. ophicalcite. damourite schist. ottrelite schist. desmosite. phyllite. dynamometamorphic rock. porcelanite. eclogite. protogene. epidosite. pyroschists. erlan. quartz. erlanfels. quartzite. eulysite. quartz schist. fibrolite schist schist. garnet rock. sericite schist, etc. garnet schist. serpentine. gneiss. slate. granite gneiss. soapstone. graywacke (?). sodalite. green schists. spilosite. greenstone (also igneous). steatite. greisen. talc schist. halleflinta. topazfels. hornblende schist topaz rock. hornfels. zobtenite. _igneous material._ absarokite. dolerite. abyssal. dunite. adamellite. durbachite. adendiorite. effusive rock. ailsyte. ekerite. Ã�kerite. elvan. alaskite. enstatite. albitlte. eruptive rock. allivalite. essexite. allochetite. estrellite. alnölte. eulysite. alsbachite. extrusive rock. ambonite. farrisite. amherstite. felsite. analcitite. felsophyre. andesite. fergusite. anorthosite. fortunite. aphanitite. fourchite. aplite. foyaite. arkite. gabbro. atatschite. gauteite. augen gneiss (also metamorphic). garewaite. augitite. glumarrite. avezacite. gladkaite. banakite. granite. banatite. granitite. bandaite. granitoid. basalt. granodiorite. basanite. granophyre. beerbachite. greenstone (also metamorphic). bekinkinite. greisen (?). bombs. grorudite. borolanite. harrisite. bostonite. harzburgite. camptonite. haüynophyre. carmeloite. hawaiite. cascadite. hedrumite. chibinite. heumite. ciminite. holyokeite. comendite. hornblendite. complementary rocks. hypabyssal rock. coppaelite. hyperite. cortlandite. hypersthenite. cromaltite. ijolite. cumberlandite. intrusive rock. cuselite. irruptive (=intrusive) rock. dacite. isenite. dellenite. jacupirangite. diabase. jumillite. diallagite. kaiwekite. dike rock. kedabekite. diorite. kentallenite. ditroite. kenyite. _igneous material._--continued. keratophyre. perlite. kersantite. phanerite. kimberlite. phonolite. kobalaite. pierite. krablite. pitchstone. krageröite. plagiaplite. kulaite. plagioclastic. kyschytymite. plumasite. lamprophyre. plutonic rock. latite. pollenite. laugenite. porphyry. laurdalite. pulaskite. laurvikite. pumice. lava. pyroxenite. lestiwarite. rhombenporphyry. leucite basalt. rhyolite. leucite tephrite. rizzonite. leucitite. rockalite. leucocratic. santorinite. lherzolite. sanukite. limbergite. saxonite. lindoite. scyelite. liparite. shastaite. litchfieldite. shonkinite. lithoidite. shoshonite. luciitss. soda granite. lujaurite. sölvsbergite. madrupite. sommaite. maenaite. spessartite. magma basalt. sussexite. malchite. syenite. malignite. taimyrite. mangerite. tawite. mariupolite. tephrite. melaphyre. teschenite. melilite basalt. theralite. mesanite. tilaite. mica peridotite. tinguaite. minette. tjosite. missourite. tonalite. monchiquite. tonsbergite. mondholdeite. tordrillite. monmouthite. toscanite (?). monzonite. trachy-andesite. mugearite. trachyte. naujaite. trap. nelsonite. troctolite. nephelinite. umptekite. nevadite. unakite. nordmarkite. ungaite. norite. urtite. obsidian. valbellite. odinite. venanzite. orbite. verite. orendite. vitrophyre. ornöite. vogesite. orthophyre. volcanic rock. ortlerite. volhynite. ouachitite. vulsinite. paisanite. websterite. pantellerite. wehrlite. pegmatite. windsorite. peridotite. wyomingite. perknite. yamaskite. index. a. abbreviations, forms of. - adhesive materials, choice. alaska, maps of, reuse of. albertype. _see_ photogelatin processes. apparatus, photographs of, preferred to sketches. approval of finished drawings, features to be covered by. of illustrations, regulations governing. areas, patterns used to distinguish. patterns used to distinguish, plate showing. army, corps of engineers of the, maps published by. artotype. _see_ photogelatin processes. atlases, published, use of. b. base maps. _see_ maps, base. bleaching photographic prints, method and solutions for. border for maps, width and use of. - bristol board, kind mid sizes used. , brash and pencil drawings, materials and methods used in making. - , brushes, kinds and sizes used. - , c. celluloid transferring, process of. requisitions for. cerotype process, description and advantages of. - changes in engravings, possible kinds of. - , changes in original material, draftsman to consult author on. chemical elements, names and symbols of. chromolithography, description of. - civil divisions, lettering of. , coal beds, indication of thickness of. coast and geodetic survey charts, use of. collotype. _see_ photogelatin processes. coloring materials, use of. colors, standard, for geologic maps. - use of, for ground-water features. - on original geologic maps. - commas, form of. use of, in numbers. contours, drawing of. - cooperation, mention of. copper, engraving on. , etching in relief on, process and advantages of. copying methods of. - corrections. _see_ changes. cost of photo-engravings. , , , county maps, use of. crayons, wax, use of. , , credit for data of maps, indication of. crystals, drawings of, making and lettering of. cultural features, lettering of. - list of. - curves, date showing. cuts. _see_ engravings. d. details of a geologic map, plate showing. diagrams, drawing and lettering of. features of, plate showing. original, general requirements for. - director of the survey, order by. divisions of plates and figures, serial letters and numbers for. drafting table, shadowless, description of. - shadowless, use of. , , draftsmen, detail of, to aid author. detail of, to prepare base maps. - experience and reading required by. - general treatment of material by. - drainage features, depiction of. - drawing instruments, list of. drawing materials, kinds used. - , - , , drawings, authors', draftsmen may aid in making. authors', editorial revision of. finished, general requirements for. - requests for photographs of. duplicates of engravings, charges for. e. effectiveness of illustrations, elements that produce. , electrotypes of engravings, charges for. elements, chemical, names and symbols of. engraving on stone, process of. - _see also_ lithography. engravings, changes in. - original, time of keeping. erasers, injury to paper by. kinds used. , - erasures, smoothing paper after. explanations on maps, arrangement and lettering of. , - f. figures, differences from plates. - divisions of, serial letters for. methods of inserting, plate showing. formations, geologic, use of letter symbols for. - fossils. _see_ specimens. four-color process, advantage of. g. gas wells, symbols for. generalization, true, meaning of. geographic tables and formulas (bull. ), use of. , geologic periods of time, names of. gouache, use of. , great lakes surveys, maps published by. greek letters, forms, names, and english sounds of. ground-water features, symbols representing. - h. hachuring, use of. half-tone engraving, preparation of copy for. - process and advantages of. - three-color process of. - half tones, changes in. prints of, showing effects produced by different screens. requirements for printing. heliotype. _see_ photogelatin processes. hill shading, use of. - hydrographic features, lettering of. representation of. - hypsographic features, lettering of. i. illustrations, kinds of. - inks, kinds used. , methods of using. inserting plates and figures, methods of, plate showing. instruments, draftsmen's, list of. j. japanese transparent water colors, use of. l. land office maps, scales and detail of. - latitude, length of ° of, at intervals of °. lending of photographs and drawings, rules governing. letter symbols, use of, on geologic maps. - lettering, directions for. - for lithographing. for names of streams. , on diagrams. on drawings of crystals. on original maps. on plans and cross sections of mines. - reduction sheet used in, plate showing. use of type for. - light, direction and gradation of. lithographs, printing and insertion of. lithography, original process of. - _see also_ engraving on stone. longitude, length of ° of, at latitudes ° to °. m. map of the world, millionth-scale, use of, for base maps. maps, areal patterns for, drawing of. - bar scales for. - base, conventional symbols used on. - including new data, how obtained. - indication of sources on. of the united states on small scales, use of. published maps available for. - reuse of, to be approved. black and whits, patterns used on, plate showing. borders for. - cultural features on. - enlargement and reduction of. explanations for. , - geologic, details of, plate showing. printing of. - standard colors for. - hydrographic features on. - lettering on. - materials used for drawing. - orientation of. original, margin required on. original base, amount of detail on. must be free from colors and symbols. preparation of. - , - original geologic, method of coloring. - projection for. - , - reduction or enlargement of, marking for. - relief on. - standard scales for. symbols used on. - drawing of. plates showing. , titles for. topographic, scales of. - mathematical signs, forms and names of. measures, linear, metric equivalents of. measuring scales for map projection, use of. meridians used on public-land maps, diagram showing. metric measures, english equivalents of. millionth-scale map, use of. mine plans, conventional lines for. features of. - symbols used on, plate showing. minerals. _see_ rocks. mississippi river commission, maps published by n. names of rocks. - national forest maps and proclamations, use of. o. offset process, description of. oilwells, symbols for. opaquing, meaning of. , , orientation of maps, requirements for. original drawings, general treatment of, by draftsmen. - preparation of. - outdoor sketches, redrawing of. - p. panoramas, construction of. paper, kinds used for drawings. - , , , , pastes, use of. patterns, areal, method of drawing. - areal, plate showing. pen drawings, materials and methods used in making. - , - pencils, colored, use of. drawing, quality and grades of. , pens, kinds of, used for drawing. , , photoengraving, cost of. , , , general features of. - photoengravings, printing and insertion of. photogelatin processes, description of. - photographs, adaptation of. bleaching of. care needed in taking and handling. , , - copyrighted, consent for use of. - duplicate prints of, requests for. mounting and numbering of. , - poor, mating of drawings over. - preparation of, for half-tone engraving. - record of source of. selection of. - retouching of. , - suitability of. unpublished, issue and use of. photolithographs, changes in. photolithography, description of. - planographic process, description of. plans of mines, drawing and lettering of. , - symbols used on, plate showing. plates, differences from figures. - divisions of, serial letters and numbers for. grouping small illustrations on. - methods of inserting, plate showing. political divisions, lettering of. , post-route maps, scales and detail of. projection for maps, preparation and checking of. - , - proofs, changes in. correction of. - duplicate, supplying of. submittal of. public-land maps, meridians, parallels, and township lines used on, diagram showing. public works, lettering of. punctuation marks, forms of. purpose of illustrations in survey reports. , r. railroad surveys, data for maps obtainable from. railroads, names of, on maps. reduction of maps, marking drawings for. - means of. reduction sheet for lettering, plate showing. use of. relief, methods of expressing. - reproduction of illustrations, processes for. - relation of, to the drawing supplied. , reticulation, sketching by. retouching of photographs, materials and method used in. , - reuse of illustrations, procedure for. - rocks, igneous, names of. - metamorphic, names of. sedimentary, names of. - symbols used to distinguish. _see also_ specimens. roman numerals, numbers expressed by. rubber, liquid, use of. s. scales, bar, forms of. - measuring for projection of maps. standard, of maps. scope of this manual. screens, half-tone prints showing effects produced by. selection of illustrations, considerations governing. - sections, columnar, original drawings for. columnar, symbols used in, plate showing. structure, combination of, with views of topography. - drawing of. - original drawings for. - symbols used in, plate showing. vertical exaggeration of. shading, kinds used. signs, mathematical, forms and names of. sises of illustrations. - , specimens, borrowed and fragile, care of. drawings of, methods of making. - paleontologic, transmittal of. photographs of, how printed. how used. - springs, symbols for. , state maps, use of. stipple, production of. , stone, engraving on. - streams, drawing of. - lettering names of. submittal of illustrations. symbols, drawing of. , for ground-water features, uniformity needed in. - for maps and mine plans, plates showing. , uniform use of. , - for oil and gas wells, features of. for structure and columnar sections, plate showing. lithologic, use of. t. three-color half-tones, process of making. - titles of illustrations, arrangement and place of. printing of. - wording and lettering of. tooling on half-tones, effects obtained by. , topographic atlas sheets, scales of. tracing, method of. - use of colors in. - tracing linen, use of. - transferring, celluloid, process of. celluloid, requisitions for. type, lettering with. - styles and sizes of. v. value of illustrations in survey reports. vara, length of. vignetting, effect obtained by. w. wall map of the united states, use of, for basemaps. water colors, use of. , , waterlining, use of. wax engraving, process and advantages of. - wells, symbols for. , wood engraving, process of. - z. zinc etchings, changes in. - drawings for. insertion of. making and advantages of. - [illustration: circle] * * * * * transcriber's note paragraphs split by illustrations were rejoined. where greek characters occurred in the original, [greek: ] was substituted for them. to see these characters, view the utf- or html version. transcriber's note whole and fractional parts of numbers are displayed as - / . text emphasis is denoted as follows: _italic_ and =bold=. extinct monsters. [illustration: plate xi. a gigantic horned dinosaur, triceratops prorsus. length about feet.] extinct monsters. _a popular account of some of the larger forms of ancient animal life._ by rev. h. n. hutchinson, b.a., f.g.s., author of "the autobiography of the earth," and "the story of the hills." with illustrations by j. smit and others. _fifth and cheaper edition._ london: chapman & hall, ld. . _all rights reserved._ "the possibilities of existence run so deeply into the extravagant that there is scarcely any conception too extraordinary for nature to realise."--agassiz. preface by dr. henry woodward, f.r.s. keeper of geology, natural history museum. i have been requested by my friend mr. hutchinson, to express my opinion upon the series of drawings which have been prepared by that excellent artist of animals, mr. smit, for this little book entitled "extinct monsters." many of the stories told in early days, of giants and dragons, may have originated in the discovery of the limb-bones of the mammoth, the rhinoceros, or other large animals, in caves, associated with heaps of broken fragments, in which latter the ignorant peasant saw in fancy the remains of the victims devoured at the monster's repasts. in louis figuier's _world before the deluge_ we are favoured with several highly sensational views of extinct monsters; whilst the pen of dr. kinns has furnished valuable information as to the "slimy" nature of their blood! the late mr. g. waterhouse hawkins (formerly a lithographic artist) was for years occupied in unauthorised restorations of various secondary reptiles and tertiary mammals, and about he received encouragement from professor owen to undertake the restorations of extinct animals which still adorn the lower grounds of the crystal palace at sydenham. but the discoveries of later years have shown that the dicynodon and labyrinthodon, instead of being toad-like in form, were lacertilian or salamander-like reptiles, with elongated bodies and moderately long tails; that the iguanodon did not usually stand upon "all-fours," but more frequently sat up like some huge kangaroo with short fore limbs; that the horn on its snout was really on its wrist; that the megalosaurus, with a more slender form of skeleton, had a somewhat similar erect attitude, and the habit, perhaps, of springing upon its prey, holding it with its powerful clawed hands, and tearing it with its formidable carnivorous teeth. although the bernissart iguanodon has been to us a complete revelation of what a dinosaur really looked like, it is to america, and chiefly to the discoveries of marsh, that we owe the knowledge of a whole series of new reptiles and mammals, many of which will be found illustrated within these pages. of long and short-tailed pterodactyles we now know almost complete skeletons and details of their patagia or flying membranes. the discovery of the long-tailed feathered bird with teeth--the archæopteryx, from the oolite of solenhofen, is another marvellous addition to our knowledge; whilst marsh's great hesperornis, a wingless diving bird with teeth, and his flying toothed bird, the ichthyornis dispar, are to us equally surprising. certainly, both in singular forms of fossil reptilia and in early mammals, north america carries off the palm. of these the most remarkable are marsh's stegosaurus, a huge torpid reptile, with very small head and teeth, about twenty feet in length, and having a series of flattened dorsal spines, nearly a yard in height, fixed upon the median line of its back; and his triceratops, another reptile bigger than stegosaurus, having a huge neck-shield joined to its skull, and horns on its head and snout. nor do the eocene mammals fall short of the marvellous, for in dinoceras we find a beast with six horns, and sword-bayonet tusks, joined to a skeleton like an elephant. latest amongst the marvels in modern palæontological discovery has been that made by professor fraas of the outline of the skin and fins in ichthyosaurus tenuirostris, which shows it to have been a veritable shark-like reptile, with a high dorsal fin and broad fish-tail, so that "fish-lizard" is more than ever an appropriate term for these old liassic marine reptiles. as every palæontologist is well aware, restorations are ever liable to emendation, and that the present and latest book of extinct monsters will certainly prove no exception to the rule is beyond a doubt, but the author deserves our praise for the very boldness of his attempt, and the honesty with which he has tried to follow nature and avoid exaggeration. every one will admire the simple and unaffected style in which the author has endeavoured to tell his story, avoiding, as far as possible, all scientific terms, so as to bring it within the intelligence of the unlearned. he has, moreover, taken infinite pains to study up his subject with care, and to consult all the literature bearing upon it. he has thus been enabled to convey accurate information in a simple and pleasing form, and to guide the artist in his difficult task with much wisdom and intelligence. that the excellence of the sketches is due to the artist, mr. smit, is a matter of course, and so is the blame, where criticism is legitimate; and no one is more sensible of the difficulties of the task than mr. smit himself. speaking for myself, i am _very well pleased_ with the series of sketches; and i may say so with the greater ease and freedom from responsibility, as i have had very little to do with them, save in one or two trifling matters of criticism. i may venture, however, to commend them to my friends among the public at large as the happiest set of restorations that has yet appeared. h. w. [illustration: plate xxiv. the late sir richard owen and a skeleton of dinornis maximus. (_from a photograph._)] author's preface. natural history is deservedly a popular subject. the manifestations of life in all its varied forms is a theme that has never failed to attract all who are not destitute of intelligence. from the days of the primitive cave-dwellers of europe, who lived with mammoths and other animals now lost to the world; of the ancient egyptians, who drew and painted on the walls of their magnificent tombs the creatures inhabiting the delta of the nile; of the greeks, looking out on the world with their bright and child-like curiosity, down to our own times, this old, yet ever new, theme has never failed. never before was there such a profusion of books describing the various forms of life inhabiting the different countries of the globe, or the rivers, lakes, and seas that diversify its scenery. popular writers have done good service in making the way plain for those who wish to acquaint themselves with the structures, habits, and histories of living animals; while for students a still greater supply of excellent manuals and text-books has been, and still continues to be, forthcoming. but in our admiration for the present we forget the great past. how seldom do we think of that innumerable host of creatures that once trod this earth! how little in comparison has been done for _them_! our natural-history books deal only with those that are alive now. few popular writers have attempted to depict, as on a canvas, the great earth-drama that has, from age to age, been enacted on the terrestrial stage, of which we behold the latest, but probably not the closing scenes. when our poet wrote "all the world's a stage," he thought only of "men and women," whom he called "merely players," but the geologist sees a wider application of these words, as he reviews the drama of past life on the globe, and finds that animals, too, have had "their exits and their entrances;" nay more, "the strange eventful history" of a human life, sketched by the master-hand, might well be chosen to illustrate the birth and growth of the tree of life, the development of which we shall briefly trace from time to time, as we proceed on our survey of the larger and more wonderful animals of life that flourished in bygone times. we might even make out a "seven ages" of the world, in each of which some peculiar form of life stood out prominently, but such a scheme would be artificial. there is a wealth of material for reconstructing the past that is simply bewildering; and yet little has been done to bring before the public the strange creatures that have perished.[ ] [ ] figuier's _world before the deluge_ is hardly a trustworthy book, and is often not up to date. the restorations also are misleading. professor dawson's _story of the earth and man_ is better; but the illustrations are poor. nicholson's _life-history of the earth_ is a student's book. messrs. cassells' _our earth and its story_ deals with the whole of geology, and so is too diffusive; its ideal landscapes to the writer it is a matter of astonishment that the and restorations leave much to be desired. discoveries of marsh, cope, leidy, and others in america, not to mention some important european discoveries, should have attracted so little notice in this country. in the far and wild west a host of strange reptiles and quadrupeds have been unearthed from their rocky sepulchres, often of incredibly huge proportions, and, in many cases, more weird and strange than the imagination could conceive; and yet the public have never heard of these discoveries, by the side of which the now well-known "lost creations" of cuvier, buckland, or conybeare sink into the shade. for once, we beg leave to suggest, the hungry pressman, seeking "copy," has failed to see a good thing. descriptions of some of "marsh's monsters" and how they were found, might, one would think, have proved attractive to a public ever on the look out for something new. professor huxley, comparing our present knowledge of the mammals of the tertiary era with that of , states that the discoveries of gaudry, marsh, and filhol, are "as if zoologists were to become acquainted with a country hitherto unknown, as rich in novel forms of life as brazil or south america once were to europeans." the object of this book is to describe some of the larger and more monstrous forms of the past--the lost creations of the old world; to clothe their dry bones with flesh, and suggest for them backgrounds such as are indicated by the discoveries of geology: in other words, to endeavour, by means of pen and pencil, to bring them back to life. the ordinary public cannot learn much by merely gazing at skeletons set up in museums. one longs to cover their nakedness with flesh and skin, and to see them as they were when they walked this earth. our present imperfect knowledge renders it difficult in some cases to construct successful restorations; but, nevertheless, the attempt is worth making: and if some who think geology a very dry subject, can be converted to a different opinion on reading these pages, we shall be well rewarded for our trouble. we venture to hope that those who will take the trouble to peruse this book, or even to look at its pictures, on which much labour and thought have been expended, will find pleasure in visiting the splendid geological collection at cromwell road. we have often watched visitors walking somewhat aimlessly among those relics of a former world, and wished that we could be of some service. but, if this little book should help them the better to understand what they see there, our wish will be accomplished. another object which the writer has kept in view is to connect the past with the present. it cannot be too strongly urged that the best commentary on the dead past is the living present. it is unfortunate that there is still too great a tendency to separate, as by a great gulf, the dead from the living, the past from the present, forms of life. the result of this is seen in our museums. fossils have too often been left to the attention of geologists not always well acquainted with the structures of living animals. the more frequent introduction of fossil specimens side by side with modern forms of life would not only be a gain to the progress and spread of geological science, but would be a great help to students of anatomy and natural history. the tree of life is but a mutilated thing, and half its interest is gone, when the dead branches are lopped off. it is, perhaps, justifiable to give to the term "monster" a somewhat extended meaning. the writer has therefore included in his menagerie of extinct animals one or two creatures which, though not of any great size, are nevertheless remarkable in various ways--such, for instance, as the winged reptiles, and anomalous birds with teeth, of later times, and others. compared with living forms, these creatures appear to us as "monstrosities," and may well find a place in our collection. the author wishes, in a few words, to thank those friends who have rendered him assistance in his task. dr. henry woodward, f.r.s., keeper of geology, natural history museum, has from the first taken a lively interest in this little book. he kindly helped the author with his advice on difficult matters, criticising some of the artist's preliminary sketches and suggesting improvements in the restorations. with unfailing courtesy he has ever been willing, in spite of many demands on his time, to place his knowledge at the disposal of both the author and artist; and in this way certain errors have been avoided. besides this, he took the trouble to read through the proof-sheets, and made suggestions and corrections which have greatly improved the text. for all this welcome aid the author begs to return his sincere thanks. to mr. smith woodward, of the natural history museum, the author is also much indebted for his kindness in reading through the text and giving valuable information with regard to the latest discoveries. the artist, mr. smit, notwithstanding the novelty of the subject and the difficulties of the task, has thrown himself heartily into the work of making the twenty-four restorations of extinct animals. to him, also, the author is greatly indebted, and considers himself fortunate in having secured the services of so excellent an artist. to the publishers his thanks are due for their liberality in the matter of illustrations, and the readiness with which they have responded to suggestions. with regard to minor illustrations the following acknowledgments are due:-- to the palæontological society of great britain for permission to reproduce three of the illustrations in sir richard owen's great work, _british fossil reptiles_, published in their yearly volumes, viz. figs. , , and . to messrs. bell and co. for the following cuts from the late dr. gideon a. mantell's works: viz. figs. , , , , , . to messrs. a. and c. black for the following cuts from owen's _palæontology_: viz. figs. , , , . * * * * * appendix iv. contains a list of some of the works of which the writer has made use; but it would be impossible within reasonable limits to enumerate all the separate papers which have necessarily been consulted. the reader will find numerous references, such as "case y on plan," in brackets; these refer to the plan given at the end of the excellent little _guide to the exhibition galleries in the department of geology and palæontology in the natural history museum_, cromwell road (price one shilling), which visitors to the museum are advised to obtain. preface to second edition. the appearance of a second edition affords the author a pleasant opportunity of thanking the reading public, and the press, for the kind way in which his endeavour to popularise the results of modern palæontology has been received. there seem to be fashions in all things--even in sciences; and perhaps the wonderful advances we have witnessed of late years in the physical sciences on the one hand, and in biological sciences on the other, may have tended to throw palæontology somewhat into the shade. let us hope that it will not remain there long. a large number of illustrations have been added for the present edition, besides additional matter here and there in the text. three of the plates (viz. plates ii. x. xv.) have been redrawn. plate ii. shows the ichthyosaurus as interpreted by the latest discovery from würtemberg. plate x. gives a somewhat different interpretation of the stegosaurus, suggested by some remarks of mr. lydekker. a slight change will be noticed in plate xv. (brontops). plate xvii. is a great improvement on the old drawing (fig. , old edition) of the megatherium skeleton. plate xxiv., besides containing a valuable portrait of the late sir richard owen, gives another drawing of the dinornis skeleton. _april, ._ contents. page preface by dr. henry woodward v author's preface ix preface to second edition xv introduction chapter i. how extinct monsters are preserved chapter ii. sea-scorpions chapter iii. the great fish-lizards chapter iv. the great sea-lizards and their allies chapter v. the dragons of old time--dinosaurs chapter vi. the dragons of old time--dinosaurs chapter vii. the dragons of old time--dinosaurs chapter viii. flying dragons chapter ix. sea-serpents chapter x. some american monsters chapter xi. some indian monsters chapter xii. giant sloths and armadillos chapter xiii. the mammoth chapter xiv. the mastodon and the woolly rhinoceros chapter xv. giant birds chapter xvi. the great irish deer and steller's sea-cow appendices. i.--table of stratified rocks ii.--the great sea-serpent iii.--list of british localities where remains of the mammoth have been discovered iv.--literature v.--ichthyosaurs index list of full-page illustrations. plate to face page xi. a gigantic horned dinosaur, triceratops prorsus _frontispiece_ xxiv. sir richard owen and skeleton of dinornis maximus ix i. sea-scorpions ii. fish-lizards iii. pterodactyls--long-necked sea-lizard--cuttle-fish or belemnite iv. a gigantic dinosaur, brontosaurus excelsus v. thigh-bone of the largest of the dinosaurs, atlantosaurus vi. a carnivorous dinosaur, megalosaurus bucklandi vii. a gigantic dinosaur, iguanodon bernissartensis viii. a gigantic dinosaur, iguanodon mantelli ix. an armoured dinosaur, scelidosaurus harrisoni x. a gigantic armoured dinosaur, stegosaurus ungulatus xii. group of small flying dragons, or pterodactyls xiii. group of sea-serpents, elasmosaur, and fishes xiv. a large extinct mammal, tinoceras ingens xv. a huge extinct mammal, brontops robustus xvi. a gigantic hoofed mammal, sivatherium giganteum xvii. skeleton of great ground sloth of south america xviii. great ground sloth of south america, megatherium americanum xix. a gigantic armadillo, glyptodon asper xx. the mammoth, elephas primigenius xxi. the mastodon of ohio, m. americanus xxii. the woolly rhinoceros, rhinoceros tichorhinus xxiii. moa-birds xxv. the great irish deer, cervus megaceros xxvi. steller's sea-cow, rhytina gigas list of figures in text. fig. page . pterygotus anglicus . silurian merostomata . ichthyosaurus intermedius . teeth of ichthyosauri . skull of ichthyosaurus latifrons . skull of ichthyosaurus platyodon . mandibles of long-necked sea-lizards . skeleton of plesiosaurus macrocephalus . restored skeleton of brontosaurus excelsus . neck vertebræ of brontosaurus . head of diplodocus . lower jaw-bone of megalosaurus, with teeth . skeleton of megalosaurus . portion of a slab of new red sandstone . portion of a slab, with tracks . limb-bones of allosaurus . skull of ceratosaurus . skull of ceratosaurus nasicornis . skeleton of compsognathus longipes . tooth of iguanodon . skeleton of iguanodon bernissartensis . skull and skeleton of iguanodon mantelli . tracks of iguanodon . restored skeleton of scelidosaurus harrisoni . skeleton of stegosaurus ungulatus . tail vertebræ of stegosaurus . limb-bones of stegosaurus . plates of stegosaurus . head of triceratops . skeleton of triceratops prorsus . bony spines belonging to the skin of triceratops . skeleton of dimorphodon macronyx . skeleton of scaphognathus crassirostris . skeleton of pterodactylus spectabilis . skeleton of rhamphorhynchus phyllurus . skull of pteranodon . skull of mosasaurus hoffmanni . teeth of mosasaurus . lower tooth of leiodon . snout of tylosaurus . skeleton of clidastes cineriarum a. skull of platecarpus . skeleton of tinoceras ingens . skull of dinoceras mirabile . cast of brain-cavity of dinoceras mirabile . skeleton of brontops robustus . skull of sivatherium giganteum . skeleton of sivatherium giganteum . restored figure of gigantic tortoise, colossochelys atlas . the elephant victorious over the tortoise, supporting the world, and unfolding the mysteries of the "fauna sivalensis" . skeleton of scelidotherium . extinct gigantic armadillo, glyptodon clavipes . skeleton of mammoth, elephas primigenius . figure of the mammoth, engraved on mammoth ivory . skeleton of mastodon arvernensis . head of woolly rhinoceros . skeleton of the elephant-footed moa, dinornis elephantopus . skeleton of great irish deer, cervus giganteus . skeleton of rhytina gigas extinct monsters. introduction. "the earth hath gathered to her breast again and yet again, the millions that were born of her unnumbered, unremembered tribes." let us see if we can get some glimpses of the primæval inhabitants of the world, that lived and died while as yet there were no men and women having authority over the fishes of the sea and the fowls of the air. we shall, perhaps, find this antique world quite as strange as the fairy-land of grimm or lewis carroll. true, it was not inhabited by "slithy toves" or "jabber-wocks," but by real beasts, of whose shapes, sizes, and habits much is already known--a good deal more than might at first be supposed. and yet, real as it all is, this antique world--this panorama of scenes that have for ever passed away--is a veritable fairy-land. in those days of which geologists tell us, the principal parts were played, not by kings and queens, but by creatures many of which were very unlike those we see around us now. and yet it is no fairy-land after all, where impossible things happen, and where impossible dragons figure largely; but only the same old world in which you and i were born. everything you will see here is quite true. all these monsters once lived. truth is stranger than fiction; and perhaps we shall enjoy our visit to this fairy-land all the more for that reason. for not even the dragons supposed to have been slain by armed knights in old times, when people gave ear to any tale, however extravagant, could equal in size or strength the real dragons we shall presently meet with, whose actual bones may be seen in the natural history museum at south kensington. many people who visit this great museum and find their way to the geological galleries on the right, pass hastily by the cases of bones, teeth, and skeletons. these things, it seems, fail to interest them. they do not know how to interpret them. they cannot picture to themselves the kinds of creatures to which the relics once belonged; and so they pass them by and presently go to the more attractive collection of stuffed birds on the other side. there they see the feathered tribes of the air all beautifully arranged; some poised in the air by almost invisible wires; some perched on branches: but all surrounded by grass, flowers, and natural objects, imitated with marvellous reality, so that they see the birds as they really are in nature, and can almost fancy they hear them singing. now, it has often occurred to the present writer that something more might be done for the long-neglected "lost creations" of the world, to bring them out of their obscurity, that they may be made to tell to the passer-by their wondrous story. we can, however, well imagine some of our readers asking, "can these dry bones live?" "yes," we would say, "they can be made to live; reason and imagination will, if we give them proper play, provide us eyes wherewith to see the world's lost creations." to such men as cuvier, owen, huxley, and others, these dry bones _do_ live. it will be our object to describe to the reader some of the wonderful results that have rewarded the lifelong labours of such great men. we shall take some of the largest and strangest forms of life that once lived, and try to picture them as they really were when alive, whether walking on land, swimming in the sea, or flying in the air; to understand the meanings of their more obvious structures; and to form some conclusions with regard to their habits, as well as to find out, if possible, their relations,--as far as such questions have been answered by those most qualified to settle these difficult matters. all technical details, such as the general reader is unfamiliar with, will be as far as possible suppressed. let us fancy a long procession of extinct monsters passing in single file before us, and ourselves endeavouring to pick out their "points" as they present themselves to the eye of imagination. it is not, be it remembered, mere imagination that guides the man of science in such matters, for all his conclusions are carefully based on reason; and when conclusions are given, we shall endeavour to show how they have been arrived at. for millions of years countless multitudes of living animals have played their little parts on the earth and passed away, to be buried up in the oozy beds of the seas of old time, or entombed with the leaves that sank in the waters of primæval lakes. the majority of these perished beyond all recovery, leaving not a trace behind; yet a vast number of fossilised remains have been, in various ways, preserved; sometimes almost as completely as if dame nature had thoughtfully embalmed them for our instruction and delight. down in those old seas and lakes she kept her great museum, in order to preserve for us a selection of her treasures. in course of time she slowly raised up sea-beds and lake-bottoms to make them into dry land. this museum is everywhere around us. we have but to enter quarries and railway cuttings, or to search in coal-mines, or under cliffs at the sea-side, and we can consult her records. as the ancient egyptians built tombs, pyramids, and temples, from which we may learn their manner of life and partly read their history, so nature has entombed, not one race only, but many races of the children of life. her records are written in strange hieroglyphs, yet it is not difficult to interpret their meaning; and thus many an old story, many an old scene, may be pictured in the mind of man. shall we call this earth-drama a tragedy or a comedy? doubtless tragic scenes occurred at times; as, for instance, when fierce creatures engaged in deadly combat: and probably amusing, if not comic, incidents took place occasionally, such as might have provoked us to laughter, had we been there to see them. but let us simply call it a drama. backgrounds of scenery were not wanting. then, as now, the surface of the earth was clothed with vegetation, and strange cattle pastured on grassy plains. vegetation was at times very luxuriant. the forests of the coal period, with their giant reeds and club-moss trees, must have made a strange picture. then, as now, there rose up from the plains lofty ranges of mountains, reaching to the clouds, their summits clothed with the eternal snows. these, too, played their part, feeding the streams and the rivers that meandered over the plains, bringing life and fertility with them, as they do now. the sun shone and the wind blew: sometimes gently, so that the leaves just whispered in an evening breeze; at other times so violently that the giants of the forest swayed to and fro, and the seas lashed themselves furiously against rocky coasts. nor were the underground forces of the earth less active than they are now: volcanic eruptions often took place on a magnificent scale; volcanoes poured out fiery lava streams for leagues beneath their feet; great showers of ashes and fine dust were ejected in the air, so that the sun was darkened for a time, and the surface of the sea was covered for many miles with floating pumice and volcanic dust, which in time sank to the bottom, and was made into hard rock, such as we now find on the top of snowdon. earthquake shocks were quite as frequent, and no doubt the ground swayed to and fro, or was rent open as some unusually great earth-movement took place, and perhaps a mountain range was raised several feet or yards higher. all this we learn from the testimony of the rocks beneath our feet. it only requires the use of a little imagination to conjure up scenes of the past, and paint them as on a moving diorama. we shall not, however, dwell at any length on the scenery, or the vegetation that clothed the landscape at different periods; for these features are sufficiently indicated in the beautiful drawings of extinct animals by our artist, mr. j. smit. the researches of the illustrious baron cuvier, at paris, as embodied in his great work, _ossemens fossiles_, gave a great impetus to the study of organic remains. it was he who laid the foundations of the science of palæontology,[ ] which, though much has already been accomplished, yet has a great future before it. agassiz, owen, huxley, marsh, cope, and others, following in his footsteps, have greatly extended its boundaries; but he was the pioneer. [ ] palæontology is the science which treats of the living beings, whether animal or vegetable, which have inhabited this globe at past periods in its history. (greek--_palaios_, ancient; _onta_, beings; _logos_, discourse.) before his time fossil forms were very little known, and still less understood. his researches, especially among vertebrates, or backboned animals, revealed an altogether undreamed-of wealth of entombed remains. it is true the old and absurd notion that fossils were mere "sports of nature," sometimes bearing more or less resemblance to living animals, but still only an accidental (!) resemblance, had been abandoned by leibnitz, buffon, and pallas; and that daubenton had actually compared the fossil bones of quadrupeds with those of living forms; while camper declared his opinion that some of these remains belonged to extinct species of quadrupeds. it is to cuvier, however, that the world owes the first systematic application of the science of comparative anatomy, which he himself had done so much to place on a sound basis, to the study of the bones of fossil animals. he paid great attention to the relative shapes of animals, and the different developments of the same kind of bones in various animals, and especially to the nature of their teeth. so great did his experience and knowledge become, that he rarely failed in naming an animal from a part of its skeleton. he appreciated more clearly than others before him the mutual dependence of the various parts of an animal's organisation. "the organism," he said, "forms a connected unity, in which the single parts cannot change without modifications in the other parts." it will hardly be necessary to give examples of this now well-known truth; but, just to take one case: the elephant has a long proboscis with which it can reach the ground, and consequently its neck is quite short; but take away the long proboscis, and you would seriously interfere with the relation of various parts of its structure to each other. how, then, could it reach or pick up anything lying on the ground? other changes would have to follow: either its legs would require to be shortened, or its neck to be lengthened. in every animal, as in a complex machine, there is a mutual dependence of the different parts. as he progressed in these studies, cuvier was able with considerable success to restore extinct animals from their fossilised remains, to discover their habits and manner of life, and to point out their nearest living ally. to him we owe the first complete demonstration of the possibility of restoring an extinct animal. his "law of correlation" however, has been found to be not infallible; as professor huxley has shown, it has exceptions. it expresses our experience among living animals, but, when applied to the more ancient types of life, is liable to be misleading. to take one out of many examples of this law: carnivorous animals, such as cats, lions, and tigers, have claws in their feet, very different from the hoofs of an ox, which is herbivorous; while the teeth of the former group are very different to those of the latter. thus the teeth and limbs have a certain definite relation to each other, or, in other words, are correlated. again, horned quadrupeds are all herbivorous (or graminivorous), and have hoofs to their feet. the following amusing anecdote serves to illustrate cuvier's law. one of his students thought he would try and frighten his master, and, having dressed up as a wild beast, entered cuvier's bedroom by night, and, presenting himself by his bedside, said in hollow tones, "cuvier, cuvier, i've come to eat you!" the great naturalist, who on waking up was able to discern something with horns and hoofs, simply remarked, "what! horns, hoofs--graminivorous--you can't!" what better lesson could the master have given the pupil to help him to remember his "law of correlation"? cuvier's great work, entitled _ossemens fossiles_, will long remain an imperishable monument of the genius and industry of the greatest pioneer in this region of investigation. this work proved beyond a doubt to his astonished contemporaries the great antiquity of the tribes of animals now living on the surface of the earth. it proved more than that, however; for it showed the existence of a great philosophy in nature which linked the past with the present in a scheme that pointed to a continuity of life during untold previous ages. all this was directly at variance with the prevalent ideas of his time, and consequently his views were regarded by many with alarm, and he received a good deal of abuse--a fate which many other original thinkers before him have shared. it is somewhat difficult for people living now, and accustomed to modern teaching, to realise how novel were the conclusions announced by cuvier. in his _discourse on the revolutions of the surface of the globe_, translated into most european languages under the title _theory of the earth_, he lays down, among others, the two following propositions:-- . that all organised existences were not created at the same time; but at different times, probably very remote from each other--vegetables before animals, mollusca and fishes before reptiles, and the latter before mammals. . that fossil remains in the more recent strata are those which approach nearest to the present type of corresponding living species. teaching such as this gave a new impetus to the study of organic remains, and palæontology, as a science, began with cuvier. chapter i. how extinct monsters are preserved. "geology, beyond almost every other science, offers fields of research adapted to all capacities and to every condition and circumstance of life in which we may be placed. for while some of its phenomena require the highest intellectual powers, and the greatest attainments in abstract science for their successful investigation, many of its problems may be solved by the most ordinary intellect, and facts replete with the deepest interest may be gleaned by the most casual observer."--mantell. let us suppose we are visiting a geological museum for the first time, passing along from one department to another with ever-increasing wonder--now admiring the beautiful polished marbles from devonshire, with their delicate corals, or the wonderful fishes from the old red sandstone, with their plates of enamel; now the delicate shells and ammonites from the lias or oolites, with their pearly lustre still preserved; now the white fresh-looking shells from the isle of wight; now the ponderous bones and big teeth of ancient monsters from the wealden beds of sussex. the question might naturally occur, "how were all these creatures preserved from destruction and decay, and sealed up so securely that it is difficult to believe they are as old as the geologists tell us they are?" it will be worth our while to consider this before we pass on to describe the creatures themselves. now, in the first place, "fossils" are not always "petrifactions," as some people seem to think; that is to say, they are not all turned into stone. this is true in many cases, no doubt, yet one frequently comes across the remains of plants and animals that have undergone very little change, and have, as it were, been simply sealed up. the state of a fossil depends on several circumstances, such as the soil, mud, or other medium in which it may happen to be preserved. again, the newest, or most recent, fossils are generally the least altered. we have fossils of all ages, and in all states of preservation. as examples of fossils very little altered, we may take the case of the wonderful collection of bones discovered by professor boyd dawkins in caves in various parts of great britain. the results of many years of research are given in his most interesting book on _cave-hunting_. this enthusiastic explorer and geologist has discovered the remains of a great many animals, some of which are quite extinct, while others are still living in this country. these remains belong to a late period, when lions, tigers, cave-bears, wolves, hyænas, and reindeer inhabited our country. in some cases the caves were the dens of hyænas, who brought their prey into caverns in our limestone rocks, to devour them at their leisure; for the marks of their teeth may yet be seen on the bones. in other cases the bones seem to have been washed into the caves by old streams that have ceased to run; but in all cases they are fairly fresh, though often stained by iron-rust brought in by water that has dissolved iron out of various rocks--for iron is a substance met with almost everywhere in nature. sometimes they are buried up in a layer of soil, or "cave-earth," and at other times in a layer of stalagmite--a deposit of carbonate of lime gradually formed on the floors of caves by the evaporation of water charged with carbonate of lime. air and water are great destroyers of animal and vegetable substances from which life has departed. the autumn leaves that fall by the wayside soon undergo change, and become at last separated or resolved into their original elements. in the same way when any wild animal, such as a bird or rabbit, dies in an exposed place, its flesh decays under the influence of rain and wind, so that before long nothing but dry bones is left. hamlet's wish that this "too too solid flesh would melt" is soon realised after death; and that active chemical element in the air known as oxygen, in breathing which we live, has a tenfold power over dead matter, slowly causing chemical actions somewhat similar to those that take place in a burning candle, whereby decaying flesh is converted into water-vapour and carbonic acid gas. thus we see that oxygen not only supports life, but breaks up into simpler forms the unwholesome and dangerous products of decaying matter, thus keeping the atmosphere sweet and pure; but in time, even the dry bones of the bird or rabbit, though able for a longer period to resist the attacks of the atmosphere, crumble into dust, and serve to fertilise the soil that once supported them. now, if water and air be excluded, it is wonderful how long even the most perishable things may be preserved from this otherwise universal decay. in the edinburgh museum of antiquities may be seen an old wooden cask of butter that has lain for centuries in peat--which substance has a curiously preservative power; and human bodies have been dug out of irish peat with the flesh well preserved, which, from the nature of the costume worn by the person, we can tell to be very ancient. meat packed in tins, so as to be entirely excluded from the air, may be kept a very long time, and will be found to be quite fresh and fit for use. but air and water have a way of penetrating into all sorts of places, so that in nature they are almost everywhere. water can slowly filter through even the hardest rocks, and since it contains dissolved air, it causes the decay of animal or vegetable substances. take the case of a dead leaf falling into a lake, or some quiet pool in a river. it sinks to the bottom, and is buried up in gravel, mud, or sand. now, our leaf will stand a very poor chance of preservation on a sandy or gravelly bottom, because these materials, being porous, allow the water to pass through them easily. but if it settles down on fine mud it may be covered up and become a fossil. in time the soft mud will harden into clay or shale, retaining a delicate impression of the leaf; and even after thousands of years, the brown body of the leaf will be there, only partly changed. in the case of the plants found in coal, the lapse of ages since they were buried up has been so great (and the strata have been so affected by the great pressure and by the earth's internal heat) that certain chemical changes have converted leaves and stems into carbon and some of its compounds, much in the same way that, if you heat wood in a closed vessel, you convert it into charcoal, which is mostly carbon. the coal we burn in our fires is entirely of vegetable origin, and every seam in a coal-mine is a buried forest of trees, ferns, reeds, and other plants. the reader will understand how it is that rocks composed of hardened sand or gravel, sandstones and conglomerates, contain but few fossils; while, on the other hand, such rocks as clay, shale, slate, and limestone often abound in fossils, because they are formed of what was once soft mud, that sealed up and protected corals, shell-fish, sea-urchins, fishes, and other marine animals. had they been covered up in sand the chances are that percolating water would have slowly dissolved the shells and corals, the hard coats of the crabs, and the bones of the fishes, all of which are composed of carbonate of lime; and we know that is a substance easily dissolved by water. it is in the rocks formed during the later geological periods that we find fossils least changed from their original state; for time works great changes, and too little time has elapsed since those periods for any considerable alterations to have taken place. but when we come to examine some of the earlier rocks, which have been acted upon in various ways for long periods of time, such as the pressure of vast piles of overlying rocks, and the percolation of water charged with mineral substances (water sometimes warmed by the earth's internal heat), then we may expect to find the remains of the world's lost creations in a much more mineralised condition. every fossil-collector must be familiar with examples of changes of this kind. for instance, shells originally composed of carbonate of lime are often found to have been turned into flint or silica. another curious change is illustrated in the case of a stratum found in cambridgeshire and other counties. in this remarkable layer, only about a foot in thickness, one frequently finds bones and teeth of fishes and reptiles. these, however, have all undergone a curious change, whereby they have been converted into phosphate of lime--a compound of phosphorus and lime. it abounds in "nodules," or lumps, of this substance, which, along with thousands of fossils, are every year ground up and converted by a chemical process into valuable artificial manure for the farmer. the soft parts of animals, as we have said before, cannot be preserved in a fossil state; but, as if to compensate for this loss, we sometimes meet with the most faithful and delicate impressions. thus, cuttle-fishes have, in some instances, left, on the clays which buried them up, impressions of their soft, long arms, or tentacles, and, as the mud hardened into solid rock, the impressions are fixed imperishably. examples of these interesting records may be seen at the natural history museum at south kensington. even soft jelly-fishes have left their mark on certain rocks! at a place in bavaria, called solenhofen, there is a remarkably fine-grained limestone containing a multitude of wonderful impressions. this stone is well known to lithographers, and is largely used in printing. on it the oldest known bird has left its skeleton and faithful impressions of its feathers. the footprints of birds and reptiles are by no means uncommon. such records are most valuable, for a great deal may be learned from even a footprint as to the nature of the animal that made it (see p. ). since the greater number of animals described in this book are reptiles, quadrupeds, and other inhabitants of the land, and only a few had their home in the sea, we must endeavour to try and understand how their remains may have been preserved. our object in writing this book is to interpret their story, and, as it were, to bring them to life again. each one must be made to tell its own story, and that story will be far from complete if we cannot form some idea of how it found its way into a watery grave, and so was added to nature's museum. for this purpose we must briefly explain to the reader how the rocks we see around us have been deposited; for these rocks are the tombs in which lost creations lie. go into any ordinary quarry, where the men are at work, getting out the stone in blocks to be used in building, or for use on the roads, or for some other purpose, and you will be pretty sure to notice at the first glance that the rock is arranged as if it had been built up in layers. now, this is true of all rocks that have been laid down by the agency of water--as most of them have been. true, there are exceptions, but every rule has its exceptions. if you went into a granite quarry at aberdeen, or a basalt quarry near edinburgh, you would not see these layers; but such rocks as these do not contain fossils. they have been mainly formed by the action of great heat, and were forced up to the surface of the earth by pressure from below. as they slowly cooled, the mineral substances of which they were formed gradually crystallised; and it is this crystalline state, together with the signs of movement, that tells us of their once heated state. such rocks are said to be of igneous origin (lat. _ignis_, fire). but nearly all the other rocks were formed by the action of water--that is, under water,--and hence are known to geologists as aqueous deposits (lat. _aqua_, water). they may be considered as sediments that slowly settled down in seas, lakes, or at the mouths of rivers. such deposits are in the course of being formed at the present day. all round our coasts mud, sand, and gravel are being accumulated, layer by layer. these materials are constantly being swept off the land by the action of rain and rivers, and carried down to the sea. perhaps, when staying at the sea-side, you may have noticed, after rainy and rough weather, how the sea, for some distance from the shore, is discoloured with mud--especially at the mouth of a river. the sand, being heavy, soon sinks down, and this is the reason why sand-bars so frequently block the entrance to rivers. then again, the waves of the sea beat against the sea-shore and undermine the cliffs, bringing down great fragments, which after a time are completely broken up and worn down into rounded pebbles, or even fine sand and mud. it is very easy to see that in this way large quantities of sand, gravel, and mud are continually supplied to our seas. we can picture how they will settle down; the sand not far from the shore, and the fine mud further out to sea. when the rough weather ceases, the river becomes smaller and flows less rapidly, so that when the coarse _débris_ of the land has settled down to form layers, or strata, of sand and gravel, then the fine mud will begin to settle down also, and will form a layer overlying them or further out. thus we learn, from a little observation of what is now going on, how layers of sand and mud, such as we see in a quarry, were made thousands and thousands of years ago. when we think of all the big rivers and small streams continually flowing into the sea, we shall begin to realise what a great work rain and rivers are doing in making the rocks of the future. if, at a later period, a slight upheaval of the sea-bed were to take place so as to bring it above water, and such is very likely, these materials would be found neatly arranged in layers, and more or less hardened into solid rock. the reader may, perhaps, find it rather hard at first to realise that in this simple way vast deposits of rock are being formed in the seas of the present day, and that the finer material thus derived from a continent may be carried by ocean currents to great distances; but so it is. over thousands of square miles of ocean, deposits are being gradually accumulated which will doubtless be some day turned into hard rock. just to take one example: it has been found that in the atlantic ocean, a distance of over two hundred miles from the mouth of that great river, the amazon, the sea is discoloured by fine sediment. there is another kind of rock frequently met with, the building up of which cannot be explained in the way we have pointed out; and that is limestone. this rock has not been deposited as a sediment, like clays and sandstones, but geologists have good reasons for believing that it has been gradually formed in the deeper and clearer parts of oceans by the slow accumulation of marine shells, corals, and other creatures, whose bodies are partly composed of carbonate of lime. this seems incredible at first, but the proofs are quite convincing.[ ] as professor huxley well remarked, there is as good evidence that chalk has been built up by the accumulation of minute shells as that the pyramids were built by the ancient egyptians. [ ] see _the autobiography of the earth_, p. . the science of geology reveals the startling fact that all the great series of the stratified rocks, whose united thickness is over , feet, has been mainly accumulated under water, either by the action of those powerful geological agents--rain and rivers--or through the agency of myriads of tiny marine animals. when we have grasped this idea, we have learned our first, and, perhaps, most useful lesson in geology. now let us apply what has been above explained to the question immediately before us. we want to know how the skeletons of animals living on land came to be buried up under water, among the stratified rocks that are to be seen all over our country, and most of which were made under the sea. we can answer this question by going to nature herself, in order to find out what is actually going on at the present time, by inquiring into the habits of land animals, their surroundings, and the accidents to which they are liable at sundry times and in divers manners. it is by this simple method of studying present actions that nearly all difficult questions in geology may be solved. the leading principle of the geologist is to interpret the past by the light of the present, or, in other words, to find out what happens now, in order to learn what took place ages ago; for it is clear that the world has been going on in the same way for at least as far back as geological history can take us. there has been a _uniformity_, or sameness, in nature's actions ever since living things first dwelt on the earth. just as rivers are mainly responsible for bringing down to the sea the materials of which rocks are made, so these universal carrying agents are the means by which the bodies of many animals that live in the plains, over which they wander, are brought to their last resting-place. we have only to consult the records of great floods to see what fearful havoc they sometimes make among living things, and how the dead bodies are swept away. great floods rise rapidly, so that the herds of wild animals pasturing on grassy plains are surprised by the rising waters, and, being unable to withstand the force of the water, are hurried along, and so drowned. when dead they sink to the bottom, and may, in some cases, be buried up in the _débris_ hurried along by the river; but as a rule their bodies, being swollen by the gases formed by decomposing flesh, rise again to the surface, and consequently may be carried along for many a mile, till they reach some lake, or perhaps right down to the mouth of a river, and so may be taken out to sea. one or two examples will be given to show how important is the action of such floods. sir charles lyell has given some striking illustrations of this. there was a memorable flood in the southern borders of scotland on the th of june, , which caused great destruction in the region of the solway firth. heavy rains had fallen, so that every stream entering the firth was greatly swollen. not only sheep and cattle, but even herdsmen and shepherds were drowned. when the flood had subsided, a fearful spectacle was seen on a large sand-bank, called "the beds of esk," where the waters meet; for on this one bank were found collected together the bodies of black cattle, horses, sheep, dogs, hares, together with those of many smaller animals, also the corpses of two men and one woman. humboldt, the celebrated traveller, says that when, at certain seasons, the large rivers of south america are swollen by heavy rains, great numbers of quadrupeds are drowned every year. troops of wild horses that graze in the "savannahs," or grassy plains, are said to be swept away in thousands. in java, in the year , batavian river was flooded during an earthquake, and drowned buffaloes, tigers, rhinoceroses, deer, apes, crocodiles, and other wild beasts, which were brought down to the coast by the current. in tropical countries, where very heavy rains fall at times, and rivers become rapidly swollen, floods are a great source of danger to man and beast. probably the greater number of the bodies of animals thus drowned find their way into lakes, through which rivers flow, and never reach the sea; and if the growth of sediment in such lakes goes on fairly rapidly, their remains may be buried up, and so preserved. but in many cases the bones fall one by one from the floating carcase, and so may in that way be scattered at random over the bottom of the lake, or the bed of a river at its mouth. in hot countries such bodies, on reaching the sea, run a great chance of being instantly devoured by sharks, alligators, and other carnivorous animals. but during very heavy floods, the waters that reach the sea are so heavily laden with mud, that these predaceous animals are obliged to retire to some place where the waters are clear, so that at such times the dead bodies are more likely to escape their ravages; and, at the same time, the mud with which the waters are charged falls so rapidly that it may quickly cover them up. we shall find further on that this explanation probably applies to the case of the "fish-lizards," whose remains are found in the lias formation (see p. ). but, for several reasons, sedimentary rocks formed in lakes are much more likely to contain the remains of land animals, than those that were formed in seas, and they are more likely to be in a complete state of preservation. within the last century, five or six small lakes in scotland, which had been artificially drained, yielded the remains of several hundred skeletons of stags, oxen, boars, horses, sheep, dogs, hares, foxes, and wolves. there are two ways in which these animals may have met with a watery grave. in the first place, they may have got mired on going into the water, or in trying to land on the other side, after swimming across. any one who knows scotch lakes will be familiar with the fact that their margins are often most treacherous ground for bathers. the writer has more than once found it necessary to be very cautious on wading into a lake while fishing, or in search of plants. secondly, when such lakes are frozen over in winter, the ice is often very treacherous in consequence of numerous springs; and animals attempting to cross may be easily drowned. no remains of birds were discovered in these lakes, in spite of the fact that, until drained, they were largely frequented by water-fowl. but it must be remembered that birds are protected by their powers of flight from perishing in such ways as other animals frequently do. and, even should they die on the water, their bodies are not likely to be submerged; for, being light and feathery, they do not sink, but continue floating until the body rots away, or is devoured by some creature such as a hungry pike. for these reasons the remains of birds are unfortunately very rare in the stratified rocks; and hence our knowledge of the bird life of former ages is slight. the imperfection of the record. a very little consideration will serve to convince us that the record which nature has kept in the stratified rocks is an incomplete one. there are many reasons why it must be so. it is not to be expected that these rocks should contain anything like a complete collection of the remains of the various tribes of plants and animals that from time to time have flourished in seas, lakes, and estuaries, or on islands and continents of the world. in endeavouring to trace the course of life on the globe at successive periods, we are continually met by want of evidence due to the "imperfection of the record"--to use darwin's phrase. the reasons are not far to seek. the preservation of organic remains, or even of impressions thereof, in sedimentary strata is, to some extent, a matter of chance. it is obvious that no wholly soft creature, such as a jelly-fish, can be preserved; although on some strata they have left impressions telling of their existence at a very early period. a creature, to become fossilised, must possess some hard part, such as a shell, _e.g._ an oyster (fossil oysters abound in some strata); or a hard chitinous covering, like that of the shrimp, or the trilobites of silurian times; or a skeleton, such as all the backboned (vertebrate) animals possess. but even creatures that had skeletons have not by any means always been preserved. bones, when left on the bottom of the sea, where no sediment, or very little, is forming, will decay, and so disappear altogether. as darwin points out, we are in error in supposing that over the greater part of the ocean-bed of the present day sediment is deposited fast enough to seal up organic remains before they can decay. over a large part of the ocean-bed such cannot be the case; and this conclusion has, of late years, been confirmed by the observations made during the fruitful voyage of h.m.s. _challenger_ in the atlantic and pacific oceans. again, even in shallower parts of the old seas, where sand or mud was once deposited, fossilisation was somewhat accidental; for some materials, being porous, allow of the percolation of water, and in this way shells, bones, etc., have been dissolved and lost. thus sandstone strata are always barren in fossils compared to shales and limestones, which are much less pervious. to take examples from our own country, the new red sandstone of the south-west of england, the midland counties, cheshire, and other parts contains very few fossils indeed, while the clays and limestones of the succeeding lias period abound in organic remains of all sorts. even insects have left delicate impressions of their wings and bodies! while shells, corals, encrinites, fish-teeth, and bones of saurians are found in great numbers. again, it must be borne in mind that the series of stratified rocks known to geologists is not complete or unbroken. they have been well compared to the leaves of a book on history, of which whole chapters and many separate pages have been torn out. these gaps, or "breaks," are due to what is called "denudation;" that is to say, a great many rocks, after having been slowly deposited in water, have been upraised to form dry land, and then, being subjected for ages to the destroying action of "rain and rivers," or the waves of the sea, have been largely destroyed. such rocks, in the language of geology, have been "denuded;" that is, stripped off, so that the underlying rocks are left bare. but the process of rock-making does not go on continuously in any one area. sedimentary strata have been formed in slowly sinking areas. but, if subsidence ceases, and the downward movement becomes an upward one, then the bed of the sea is converted into dry land, and the geological record is broken; for aqueous strata do not form on dry land. blown sands and terrestrial lava-flows are exceptions; but such accumulations are very small and insignificant, and may therefore be neglected, especially as they contain no fossils. in this way, as well as by the process of "denudation" already alluded to, breaks occur; and these breaks often represent long intervals of time. there are several such gaps in the british series of stratified rocks; and it is partly by means of these breaks, during which important geographical and other changes took place, that sedimentary rocks have been classified and arranged in groups representing geological periods. thus, the cainozoic, or tertiary, rocks of the thames' basin are separated by a long "break" from those of the preceding cretaceous period. during that interval great changes in animal life took place, whereby, in the course of evolution, new types appeared on the scene. (see table of strata, appendix i.) another cause interfering with the record is to be found in those important internal changes that have taken place in stratified rocks--often over large areas--which may be ascribed to the influence of heat and pressure combined. this process of change, whereby soft deposits have been altered or "metamorphosed" into hard crystalline rocks, is known as "metamorphism." metamorphic rocks have lost not only their original structure and appearance, but also their included organic remains, or fossils. thus, when a soft limestone has been converted by these means into crystalline statuary marble, any fossils it may once have contained have been destroyed. it is true that this applies more to older and lower deposits,--for the lowest are the oldest--but there can be no doubt that valuable records of the forms of life which peopled the world in former periods have been lost by this means. and lastly, it must ever be borne in mind that, as yet, our knowledge of the stratified rocks of the earth's crust is very limited. in course of time, no doubt, this deficiency will be to a great extent made good; but it will take a long time. already, within the last thirty years, the labours of zealous geologists in the colonies and in various countries have added largely to our knowledge of the geological record. still, only a small portion of the earth's surface has at present been explored; and doubtless one may look forward to future discoveries of extinct forms of animal and plant life as wonderful and strange as those that have been of late years unearthed in the "far west," in africa, and india. the siwalik hills of northern india offer a rich harvest of fossils to future explorers. already, one remarkable and large horned quadruped has come from this region; and it is known that other valuable treasures are sealed up within these hills, only awaiting the "open sesame" of some enterprising explorer to bring them to light. as previously pointed out, deposits formed in lakes are the most promising field for geologists in search of the remains of old terrestrial quadrupeds and reptiles; but, unfortunately, such deposits are rare. it is very much to be regretted that the carelessness and indifference of ignorant workmen in quarries, clay-pits, and railway cuttings have sometimes been the cause of valuable fossils being broken up, and so lost for ever. unless they are accustomed to the visits of fossil-collectors who will pay them liberally for their finds, the men will not take the trouble to preserve any bones they may come across in the course of their work. (an example of this negligence will be found on p. .) but when once they realise that such finds have what political economists call an "exchange value," or, in other words, can be turned into money, it is astonishing what zealous guardians of nature's treasures they become! for this reason collectors often find what professor bonney calls the "silver hammer"--in other words, cash--more effective than the iron implement they carry with them. chapter ii. sea-scorpions. "and some rin up the hill and down dale, knapping the chucky stanes to pieces wi' hammers like sae many road-makers run daft. they say 'tis to see how the warld was made."--_st. ronan's well._ our first group of monsters is taken from a tribe of armed warriors that lived in the seas of a very ancient period in the world's history. like the crabs and lobsters inhabiting the coasts of britain, they possessed a coat of armour, and jointed bodies, supplied with limbs for crawling, swimming, or seizing their prey. they were giants in their day, far eclipsing in size any of their relations that have lived on to the present time. some of them, such as the pterygotus (fig. , p. ), attained a length of nearly six feet. they belonged to the humbler ranks of life, and, if now living, would without doubt be assigned, by fishmongers ignorant of natural history, to that vague category of "shell-fish" in which they include crabs, lobsters, mussels, etc. these lobster-like creatures, though claiming no relationship with the higher ranks of animals, may well engage our attention, not only for their great size, but also for their strange build. [illustration: plate i. sea-scorpions. _pterygotus anglicus._ _eurypterus._ _stylonurus._ length feet.] there are no living creatures quite like them. certainly they are not true lobsters, and yet we may consider them to be first or second cousins of those ten-footed crustaceans[ ] of the present day--lobsters, crabs, and shrimps, so welcome on the tables of both rich and poor. some naturalists say that their nearest relations at the present day are the king-crabs inhabiting the china seas and the east coast of north america; and there certainly are some points of resemblance between them. others say that they are related to scorpions, and for this reason we call them sea-scorpions. (see plate i.) [ ] crustaceans are a class of jointed creatures (articulate animals), possessing a hard shell or crust (lat. _crusta_), which they cast periodically. they all breathe by gills. the first feature we notice in these creatures is the way in which their bodies and limbs are divided into rings or joints. this fact tells us that they belong to that great division of animals called "articulates," of which crabs, lobsters, spiders, centipedes, and insects are examples. the celebrated linnæus called them _all_ insects, because their bodies are in this way cut into divisions.[ ] but this arrangement has since been abandoned. however, they are all built upon this simple plan, their bodies being like a series of rings, to which are attached paired appendages or limbs, also composed of rings, some longer and some shorter. now, there must be something very fitting and appropriate in this arrangement, for the creatures that are thus built up are far more numerous than any other group of animals. they must be particularly well qualified to fight the battle of life; for like a victorious army they have taken the world by storm, and still remain in possession. we find them everywhere--in seas, rivers, and lakes; in fields and forests; in the soil, and in all sorts of nooks and crannies; in the air, and even upon or inside the bodies of other animals. some of them, such as ants, bees, and wasps, show an intelligence that is simply marvellous, and have acquired social habits which excite our admiration. [ ] lat. _in_, into, and _secta_, cut. articulate animals are a very ancient race, as well as a flourishing one, for the oldest rocks containing undoubted fossils--namely, certain slates found in wales and the lake district--tell us of a time when shallow seas swarmed with little articulate animals known as _trilobites_. they were in appearance something like wood-lice of the present day; and the record of the rocks tells us plainly that creatures built upon this plan have flourished ever since. we mention this because they are related to the king-crabs of the present day, and therefore to the huge old-fashioned sea-scorpions we are now considering. [illustration: fig. .--_pterygotus anglicus._ (after woodward.) . upper side. . under side.] the best-known and largest of these creatures is represented in fig. . it has received the name _pterygotus_ (or wing-eared) from certain fanciful resemblances pointed out by the quarrymen. it was first discovered, along with others of its kind, by hugh miller, at carmylie in forfarshire, in a certain part of the old red sandstone (see table of strata, appendix i.) known as the arbroath paving-stone. the quarrymen, in the course of their work, came upon and dug out large pieces of the fossilised remains of this creature. its hard coat of jointed armour bore on its surface curious wavy markings that suggested to their minds the sculptured feathers on the wings of cherubs--of all subjects of the chisel the most common. hence they christened these remains "seraphim." they did not succeed in getting complete specimens that could be pieced together; and the part to which this fanciful name was given turned out to be part of the under side below the mouth. it was composed of several large plates, two of which are not unlike the wings of a cherub in shape. hugh miller says in his classic work, _the old red sandstone_--"the form altogether, from its wing-like appearance, its feathery markings, and its angular points, will suggest to the reader the origin of the name given it by forfarshire workmen." a correct restoration, in proportion to the fragments found in the lower old red sandstone, would give a creature measuring nearly six feet in length, and more than a foot across. _pterygotus anglicus_ may therefore be justly considered a monster crustacean. the illustrious cuvier, who, in the eighteenth century founded the science of comparative anatomy (see p. ), astonished the scientific world by his bold interpretations of fossil bones. from a few broken fragments of bone he could restore the skeleton of an entire animal, and determine its habits and mode of living. when other wise men were unable to read the writing of nature on the walls of her museum--in the shape of fossil bones--he came forward, like a second daniel, to interpret the signs, and so instructed us how to restore the world's lost creations. hugh miller submitted the fragments found at balruddery to the celebrated naturalist agassiz, a pupil of cuvier, who had written a famous work on fossil fishes; and he says that he was much struck with the skill displayed by him in piecing together the fragments of the huge pterygotus. "agassiz glanced over the collection. one specimen especially caught his attention--an elegantly symmetrical one. his eye brightened as he contemplated it. 'i will tell you,' he said, turning to the company--'i will tell you what these are--the remains of a huge lobster.' he arranged the specimens in the group before him with as much ease as i have seen a young girl arranging the pieces of ivory in an indian puzzle. there is a homage due to supereminent genius, which nature spontaneously pays when there are no low feelings of jealousy or envy to interfere with her operations; and the reader may well believe that it was willingly rendered on this occasion to the genius of agassiz." agassiz himself, previous to this, had considered such fragments as he had seen to be the remains of fishes. as we have said before, this creature was _not_ a true lobster; but agassiz, when he expressed the opinion just quoted, was not far off the mark, and did great service in showing it to be a crustacean. there were no lobsters or scorpions at that early period of the world's history, and this creature, with its long "jaw-feet" and powerful tail, was a near approach to a king-crab on the one hand and scorpion on the other. if living now, it would no doubt command a high price at billingsgate; but, then, it would be a dangerous thing to handle when alive, and might be more troublesome to catch than our crabs or lobsters. the front part of its body was entirely enveloped in a kind of shield, called a carapace, bearing near the centre minute eyes, which probably were useless, and at the corners two large compound eyes, made up of numerous little lenses, such as we see in the eye of a dragon-fly. this is clearly proved by certain well-preserved specimens. there are five pairs of appendages, all attached under or near the head. behind the head follow thirteen rings, or segments, the last of which forms the tail, two at least of these bore gills for breathing. all but two of them, below the mouth, must have been beautifully articulated, so as to allow them to move freely, as we see in the lobster of the present day. but look at that lowest and largest pair of appendages, the end joints of which are flattened out, and you will see that they must have been a powerful oar-like apparatus for swimming forwards. we can fancy this creature propelling itself much in the same way as a "water-beetle" rows itself through the water in a pond. in all other crustaceans the antennæ are used for feeling about, but in the pterygotus they are used as claws for seizing the prey. in general external appearance, this huge pterygotus greatly reminds us of a tiny fresh-water crustacean, known as cyclops--because it has only one eye, like the giant in homer's _odyssey_. this little creature, which is only / inch in length, is an inhabitant of ponds. from its large eyes, powerful oar-like limbs, or appendages, and from the general form of its body, dr. henry woodward (the author of a learned monograph on these creatures) concludes that the pterygotus was a very active animal; and the reader will easily gather from its pair of antennæ, converted at their extremities into nippers, and from the nature of its "jaw-feet," that the creature was a hungry and predaceous monster, seizing everything eatable that came in its way. the whole family to which it belongs--including pterygotus, eurypterus, slimonia, stylonurus, and others--seems to have been fitted for rather rapid motion, if we may judge from the long tapering and well-articulated body. in two forms (pterygotus and slimonia) the tail-flap probably served both as a powerful propeller, and as a rudder for directing the creature's course; but others, such as eurypterus and stylonurus, had long sword-like tails, which may have assisted them to burrow into the sand, in the same way that king-crabs do. eurypterus remipes is shown in fig. . it has been stated above that our sea-scorpions are related to the king-crabs. now, this creature, it is well known, burrows into the mud and sand at the bottom of the sea. this it does by shoving its broad sharp-edged head-shield downwards, working rapidly at the same time with its hinder feet, or appendages, and by pushing with the long spike that forms a kind of tail. it will thus sink deeper and deeper until nothing can be seen of its body, and only the eyes peep out of the mud. it will crawl and wander about by night, but remains hidden by day. some of them are of large size, and occasionally measure two feet in length. they possess six pairs of well-formed feet, the joints of which, near the body, are armed with teeth and spines, and serve the purpose of jaws, being used to masticate the food and force it into the mouth, which is situated between them. [illustration: fig. .--_silurian merostomata._ . _stylonurus._ . _eurypterus._ (after woodward.)] now, this fact is of great importance; for it helps us to understand the use of the four pairs of "jaw-feet" in our sea-scorpions. what curious animals they must have been, using the same limbs for walking, holding their prey, and eating! look at the broad plates at the base of the oar-like limbs, or appendages, with their tooth-like edges. these are the plates found by hugh miller's quarrymen, and compared by them to the wings of seraphim. you will easily perceive that by a backward and forward movement, they would perform the office of teeth and jaws, while the long antennæ with their nippers--helped by the other and smaller appendages--held the unfortunate victim in a relentless grasp. and even these smaller limbs, you will see from the figure, had their first joints, near the mouth, provided with toothed edges like a saw. with regard to the habits of sea-scorpions, it would not be altogether safe to conclude that, because in so many ways they resembled king-crabs, they therefore had the same habit of burrowing into the soft muddy or sandy bed of the sea, as some authorities have supposed. seeing that there is a difference of opinion on this subject, the author consulted dr. woodward on the question, and he said he thought it unlikely, seeing that, in some of them, such as the pterygotus, the eyes are placed on the margin of the head-shield; for it would hardly care to rub its eyes with sand. whether it chose at times to bury its long body in the sand by a process of wriggling backwards, as certain modern crustaceans do, we may consider to be an open question. if only sea-scorpions had not unfortunately died out, how interesting it would be to watch them alive, and to see exactly what use they would make of their long bodies, tail-flaps, and tail-spikes! were they nocturnal in their habits, wandering about by night, and taking their rest by day? such questions, we fear, can never be answered. but their large eyes would have been able to collect a great deal of light when the moon and stars feebly illumined the shallower waters of the seas of old red sandstone times; and so there is nothing to contradict the idea. now, it is an interesting fact that young crabs, soon after they are hatched, have long bodies somewhat similar to those of our sea-scorpions, with a head-shield under which are their jaw-feet, and then a number of free body-rings without any appendages. these end in a spiked tail. as the crab grows older, he ceases to be a free-swimming animal--for which kind of life his long body is well suited,--tucks up his long tail, and takes to crawling instead. thus his body is rendered more compact and handy for the life he is going to lead. lobsters, on the other hand, can swim gently forwards, or dart rapidly backwards. thus we see that the ten-footed crustaceans of the present day are divided into two groups--the long-tailed and free-swimming forms, such as lobsters, shrimps, and cray-fishes; and the short-tailed crawling forms, namely, the crabs. now, in the same way, pterygotus and its allies were long-tailed forms, while the king-crabs are short-tailed forms. so were the trilobites of old. hence we learn that, ages and ages ago, before the days of crabs and lobsters, there were long-tailed and short-tailed forms of crustaceans, just as there are now, only they did not possess true walking legs. they belonged to quite a different order, called "thigh-mouthed" crustaceans, merostomata, because their legs are all placed near the mouth; and, as we have already learned, were used for feeding as well as for purposes of locomotion. now, one of the many points of interest in pterygotus and its allies is that they somewhat resemble the crab in its young or larval state. to a modern naturalist, this fact is important as showing that crustacean forms of life have advanced since the days of the sea-scorpions. their resemblance to land-scorpions is so close that, if it were not for the important fact that scorpions breathe _air_ instead of _water_, and for this purpose are provided with air-tubes (or trachea) such as all insects have, they would certainly be removed bodily out of the crustacean class, and put into that in which scorpions and spiders are placed, viz. the arachnida. but, in spite of this important difference, there are some naturalists in favour of such a change. it will thus be seen that our name sea-scorpions is quite permissible. hugh miller described some curious little round bodies found with the remains of the pterygotus, which it was thought were the eggs of these creatures! finally, these extinct crustaceans flourished in those ages of the world's history known as the silurian and the old red sandstone periods. as far as we know, they did not survive beyond the succeeding period, known as the carboniferous.[ ] [ ] the student should consult dr. henry woodward's valuable _monograph of the british merostomata_ (palæontographical society), to which the writer is much indebted. with regard to the representation of _pterygotus anglicus_ in plate i., it has been pointed out by dr. woodward that the creature was unable to bend its body into such a position as is shown there. as in a modern lobster, or shrimp, there were certain overlapping plates in the rings, or segments, of the body, which prevented movement from side to side, and only allowed of a vertical movement. chapter iii. the great fish-lizards. "berossus, the chaldæan saith: a time was when the universe was darkness and water, wherein certain animals of frightful and compound forms were generated. there were serpents and other creatures with the mixed shapes of one another, of which pictures are kept in the temple of belus at babylon."--_the archaic genesis._ visitors to sydenham, who have wandered about the spacious gardens so skilfully laid out by the late sir joseph paxton, will be familiar with the great models of extinct animals on the "geological island." these were designed and executed by that clever artist, mr. waterhouse hawkins, who made praiseworthy efforts to picture to our eyes some of the world's lost creations, as restored by the genius of sir richard owen and other famous naturalists. his drawings of extinct animals may yet be seen hanging on the walls of some of our provincial museums; and doubtless others still linger among the natural history collections of schools and colleges. lazily basking in the sun, when it condescends to shine, and resting his clumsy carcase on the ground that forms the shore near the said geological island at sydenham, may be seen the old fish-lizard, or ichthyosaurus, that forms the subject of the present chapter. he looks awkward on land, as if longing to get into his native element once more, and cleave its waters with his powerful tail-fin. his "flippers" seem too weak to enable him to crawl on land. moreover, the most recent discoveries of dr. fraas lead us to conclude that the ichthyosaur never ventured to leave the "briny ocean" to bask upon the land. this great uncouth beast presents some curious anomalies in his constitution, being planned on different lines to anything now living, and presenting, as so many other extinct animals do, a mixture, or fusion, of types that greatly puzzled the learned men of the time when his remains were first brought to light, after their long entombment in the lias rocks forming the cliffs on the coast of dorset. some have christened him a "sea-dragon," and such indeed he may be considered. but the name ichthyosaurus, given above, has received the sanction of high authority, and, moreover, serves to remind us of the fact that, although in many respects a lizard, he yet retains in his bony framework the traces of a remote fishy ancestry. so we will call him a fish-lizard. we remember in our young days the amiable endeavours of mr. "peter parley" to introduce us to the wonders of creation; and his account of the ichthyosaurus particularly impressed itself on our youthful imagination. how surprised that inestimable instructor of youth would be could he now see the still more wonderful remains that have been brought to light from europe, asia, africa, and america! the curious quotation given at the head of the present chapter refers to a widespread belief, prevalent among the highly civilised nations of antiquity, that the world was once inhabited by dragons, or other monsters "of mixed shape" and characters. to the student of ancient history traces of this curious belief will be familiar. sir charles lyell refers to such a belief when he says, in his _principles of geology_, "the egyptians, it is true, had taught, and the stoics had repeated, that the earth had once given birth to some monstrous animals that existed no longer." it may be surprising to some, but it is undoubtedly the fact, that modern scientific truths were partly anticipated by the civilised nations of long ago. take the ideas of the ancients as interpreted from the records of egypt, chaldæa, india, and china; and you will find that our discoveries in geology, astronomy, and ethnology go far to prove that the traditions of these ancient peoples, however derived, after making due allowance for oriental allegory and poetic hyperbole, are not far from the truth. to the babylonian tradition of the monstrous forms of life at first created we have already alluded; but in other fields of discovery we find the same foreshadowing of discoveries made in our own day. take the vast cycles of egyptian tradition, wherein the stars returned to their places after a circle of constant change, only to start again on their unwearied round; the atomic theory of lucretius, now expanded and incorporated into modern chemistry; or the philosopher's pregnant saying--_omne vivum ex ovo_ ("every living thing comes from an egg"). these and other examples might be cited to show how true the old saying is, "there is nothing new under the sun." in the writings of ancient authors may be found singular notices of bones and skeletons found in "the bowels of the earth," which are referred to an imaginary era of long ago, when giants of huge dimensions walked this earth. one is inclined sometimes to wonder whether the old fables of griffins and horrid dragons may not be to some extent based upon the occasional discovery, in former times, of fossil bones, such as evidently belonged to animals the like of which are not to be seen nowadays. (see chaps. xiii. and xiv.) the illustrious cuvier, in his day, considered the fish-lizard to be one of the most heteroclite and monstrous animals ever discovered. he said of this creature that it possessed the snout of a dolphin, the teeth of a crocodile, the head and breast-bone of a lizard, the paddles of a whale or dolphin, and the vertebræ of a fish! no wonder that naturalists and palæontologists, whose realm is the natural history of the past, were obliged to make a new division, or order, of reptiles to accommodate the fish-lizard. it is obvious that a creature with such very "mixed" relationships would be out of place in any of the four orders into which living reptiles, as represented by turtles, snakes, lizards, and crocodiles are divided. here is what professor blackie says of the ichthyosaurus-- "behold, a strange monster our wonder engages! if dolphin or lizard your wit may defy. some thirty feet long, on the shore of lyme-regis, with a saw for a jaw, and a big staring eye. a fish or a lizard? an ichthyosaurus, with a big goggle eye, and a very small brain, and paddles like mill-wheels in chattering chorus, smiting tremendous the dread-sounding main." a glance at our restoration, plate ii., will show that the fish-lizard was a powerful monster, well endowed with the means of propelling itself rapidly through the water as it sought its living prey, to seize it within those cruel jaws. the long and powerful tail was its chief organ of propulsion; but the paddles would also be useful for this purpose, as well as for guiding its course. the pointed head and generally tapering body suggests a capability of rapid movement through the water; and since we know for certain that it fed on fishes, this conclusion is confirmed, for fishes are not easily caught now, and most probably were not easily caught ages ago. the personal history of the fish-lizard, merely as a fossil or "remain," is interesting; so much so, that we may perhaps be allowed to relate the circumstances of his _début_ before the scientific world, in the days of the ever-illustrious cuvier, to whom we have already alluded. but england had its share of illustrious men, too, though lesser lights compared to the founder of comparative anatomy,--such as sir richard owen, on whom the mantle of his friend cuvier has fallen; conybeare, de la beche, and dean buckland. these scientific men, aided by the untiring labours of many enthusiastic collectors of organic remains, have been the means of solving the riddle of the fish-lizard, and of introducing him to the public. by this time there is, perhaps, no creature among the host of antediluvian types better known than this reptile. the remains of fish-lizards have attracted the attention of collectors and describers of fossils for nearly two centuries past. the vertebræ, or "cup-bones," as they are often called, of which the spinal column was composed, were figured by scheüchzer, in an old work entitled _querelæ piscium_; and, at that time, they were supposed to be the vertebræ of fishes. in the year sir everard home described the fossil remains of this creature, in a paper read before the royal society, and published in their _philosophical transactions_. this fossil was first discovered in the lias strata of the dorsetshire coast. other papers followed till the year . we are chiefly indebted to de la beche and conybeare for pointing out and illustrating the nature of the fish-lizard; and that at a time when the materials for so doing were far more scanty than they are now. mr. charles könig, mr. thomas hawkins, dean buckland, sir philip egerton, and professor owen have all helped to throw light on the structure and habits of these old tyrants of the seas of that age, which is known as the jurassic period. they lived on, however, to the succeeding or cretaceous period, during which our english chalk was forming; but the liassic age was the one in which they flourished most abundantly, and developed the greatest variety. in the year a few bones were found on the dorsetshire coast between charmouth and lyme-regis, and added to the collection of bullock. they came from the lias cliffs, undermined by the encroaching sea. sir everard's attention being attracted to them, he published the notices already referred to. the analogy of some of the bones to those of a crocodile, induced mr. könig, of the british museum, to believe the animal to have been a saurian, or lizard; but the vertebræ, and also the position of certain openings in the skull, indicated some remote affinity with fishes, but this must not be pressed too far. the choice of a name, therefore, involved much difficulty; and at length he decided to call it the _ichthyosaurus_, or fish-lizard. mr. johnson, of bristol, who had collected for many years in that neighbourhood, found out some valuable particulars about these remains. the conclusions of dean buckland, then professor of geology at oxford, led sir everard to abandon many of his former conclusions. the labours of the learned men of the day were greatly assisted by the exertions of miss anning, an enthusiastic collector of fossils. this lady, devoting herself to science, explored the frowning and precipitous cliffs in the neighbourhood of lyme-regis, when the furious spring-tide combined with the tempest to overthrow them, and rescued from destruction by the sea, sometimes at the peril of her life, the few specimens which originated all the facts and speculations of those persons whose names will ever be remembered with gratitude by geologists. [illustration: fig. .--_ichthyosaurus intermedius._] probably our readers are already more or less familiar with the drawings of the fossilised remains of ichthyosauri to be seen in almost every text-book of geology. (fig. is from owen's _british fossil reptiles_.) but we recommend all who take an interest in the world's lost creations to pay a visit to the great natural history museum, at south kensington. the fossil reptile gallery contains a magnificent series of ichthyosauri, about thirty in number. of these a large number were obtained through the exertions of the late mr. t. hawkins, a somersetshire gentleman, who was a most ardent collector of fossil reptiles, and who devoted himself with great enthusiasm and unsparing energy to the acquisition of a truly splendid collection of these most interesting relics of the past. nearly sixty years ago he arranged for the purchase of his treasures by the authorities of the british museum, and thus his collection became the property of the nation. his specimens were figured and described by him in two large folio volumes. the first was published in , under the title, _memoirs of the ichthyosauri and plesiosauri_; his second, with the same plates, in , under the quaint title of _the book of the great sea-dragons_. the large lithographic drawings of his fine specimens were beautifully executed by scharf and o'neil. the plates are the only really valuable part of these two curious and ill-written books. his descriptions are not of much value, and his pages are encumbered with a vast amount of extraneous matter. the author is immensely proud of his collection, and his vanity is conspicuous throughout. instead of confining himself to descriptions of what he found, and how he found them, he continually wanders into all sorts of subjects that are, to say the least, irrelevant. in one place he introduces ancient history and mythology; in another, old testament chronology; in another, the unbelieving spirit of the age; and here and there indulges in vague unphilosophical speculations. altogether his two volumes are a curious mixture of bigotry, conceit, and unrestrained fancy, and they afforded to the present writer no small amusement. one rises from the perusal of such men's writings with a strong sense of the contrast between the humble and patient spirit in which our great men of to-day, such as professor owen, study nature and record their observations, and the vague, conceited outpourings of some old-fashioned writers. mr. hawkins tells us that his youthful attention was directed to the lias quarries, near edgarly, in somersetshire, in consequence of some strange reports. it was said that the bones of giants and infants had, at distant intervals, been found in them. these quarries he visited, and, by offers of generous payment, induced the workmen to keep for him all the remains they might find. in this way he finally obtained the co-operation of all the quarrymen in the county. [illustration: plate ii. fish-lizards. _ichthyosaurus communis._ _ichthyosaurus tenuirostris._ length about feet. fishes, _dapedius_, etc. a smaller species.] mr. hawkins thus expresses his delight on obtaining an ichthyosaurus which was pointed out to him by miss anning, near the church at lyme-regis, in the year : "who can describe my transport at the sight of the colossus? my eyes the first which beheld it! who shall ever see them lit up with the same unmitigated enthusiasm again? and i verily believe that the uncultivated bosoms of the working men were seized with the same contagious feeling; for they and the surrounding spectators waved their hats to an 'hurra!' that made hill and mossy dell echoing ring." this specimen, however, got sadly broken in its fall from the cliff; but in time he put all the pieces together again. speaking of his own collection, he says, "this stupendous treasure was gathered by me from every part of england; arranged, and its multifarious features elaborated from the hard limestone by my own hands. a tyro in collecting at the age of twelve years, i then boasted of all the antiquities that were come-at-able in my neighbourhood, but, finding that everybody beat my cabinet of coins, i addressed myself to worm-eaten books, and last to fossils." before he was twenty years of age he had obtained a very fine collection of organic remains. when, however, he complains of the philistine dulness and stupidity of quarrymen, who often, in their ignorance, break up finds of almost priceless value, we can fully sympathize. in general contour the body of the fish-lizard was long and tapering, like that of a whale (see plate ii.). it probably showed no distinct neck. the long tail was its chief organ of propulsion. we notice two pairs of fins, or paddles; one on the fore part of the body, the other on the hinder part, like the pectoral and abdominal fins of a fish. the skin was scaleless and smooth, or slightly wrinkled, like that of a whale. no traces of scales have ever been found; and if such had existed, they would certainly have been preserved, since those of fishes and crocodiles of the jurassic period have been found in considerable number and variety. it is therefore safe to conclude that such were absent in this case. in the lias strata, at least, the specimens are often preserved with most wonderful completeness (see p. ). the long and pointed jaws are a striking feature of these animals. the eyes were very large and powerful, and specially adapted, as we shall see presently, to the conditions of their life. it might, perhaps, be asked whether the fish-lizards breathed, like fishes, by means of gills. that question can easily be answered; for if they had possessed gills for taking in water and breathing the air dissolved therein, they would reveal the fact by showing a bony framework for the support of gills, such as are to be found in all fishes. these structures, known as "branchial arches," are absent; therefore the fish-lizards possessed lungs, and breathed air like reptiles of the present day. their skulls show where the nostrils were situated; namely, near the eyes, and not at the end of the upper jaw-bone. there are also passages in the skull leading from the nostrils to the palate, along which currents of air passed on their way to the lungs. being air-breathers, they would be compelled occasionally to seek the surface of the sea, in order to obtain a fresh supply of the life-giving element--oxygen; but, being cold-blooded and with a small brain, needing a much less supply of oxygen for its work, the fish-lizards had, like fishes, this advantage over whales, which are warm-blooded--that their stern-propeller, or tail-fin, could take the form best adapted for a swift, straight-forward course through the water. in the whale tribe the tail-fin is horizontal; and this is so on account of their need, as large-brained, warm-blooded air-breathers, of speedy access to the atmospheric air. were it otherwise, they would not have the means of rising with sufficient rapidity to the surface of the sea; for they have only one pair of fins. but the fish-lizards had two pairs of these appendages, and the hinder or pelvic pair no doubt were of great service in helping the creatures to come up to the surface when necessary. thus we see that the whale, with its one pair of paddles, has a tail specially planned with a view to rapid vertical movement through the water; while in the fish-lizards, who did not require to breathe so frequently, the tail-fin was planned with a view to swift and straight movement forward as they pursued their prey, and they were compensated by having bestowed upon them an extra pair of paddles. thus we learn how one part of an animal is related to and dependent upon another, and how they all work together with the greatest harmony for certain definite purposes (see p. ). [illustration: fig. .--(a) lateral and (b) profile views of a tooth of _ichthyosaurus platyodon_ (conybeare), lower lias, lyme regis, dorsetshire, (c) tooth of _ichthyosaurus communis_ (conybeare), lower lias, lyme regis, dorset.] these great marine predaceous reptiles literally swarmed in the seas of the lias period, and no doubt devoured immense shoals of the fishes of those times, whose numbers were thus to some extent kept down. there is clear proof of this in the fossilised droppings--known as "coprolites,"--which show on examination the broken and comminuted remains of the little bony plates of ganoid fishes that we know were contemporaries of these reptiles. probably young ones were sometimes devoured too. it was in the period of the lias that fish-lizards attained to their greatest development, both in numbers and variety; and the strata of that period have preserved some interesting variations. it will be sufficient here to point out two, namely, ichthyosaurus tenuirostris--an elegant little form, in which the jaws, instead of being massive and strong, were long and slender like a bird's beak; and also ichthyosaurus latifrons (fig. ), with jaws still more bird-like. our artist has attempted to show the former variety in our illustration (plate ii.). a most perfect example of this pretty little ichthyosaur, from the lower lias of street in somerset, has recently been presented to the national collection at south kensington by mr. alfred gillett, of street, and may be seen there. in this group of fish-lizards the eyes are relatively larger, and we should imagine that they were very quick in detecting and catching their prey; their paddles also have larger bones. [illustration: fig. .--skull of _ichthyosaurus latifrons_.] there is a remarkably fine specimen at burlington house, in the rooms of the geological society, of an ichthyosaurus' head, which the writer found, on measuring, to be about five feet six inches long. a cast of this head is exhibited at south kensington. the largest of the specimens in the national collection is twenty-two feet long and eight feet across the expanded paddles; but it is known that many attained much greater dimensions. judging from detached heads and parts of skeletons, it is probable that some of them were between thirty and forty feet long. a specimen of ichthyosaurus platyodon in the collection of the late mr. johnson, of bristol, has an eye-cavity with a diameter of fourteen inches. this collection is now dispersed. with regard to their habits, sir richard owen concludes that they occasionally sought the shores, crawled on the strand, and basked in the sunshine. his reason for this conjecture (which, however, is not confirmed by dr. fraas's recent discoveries) is to be found in the bony structure connected with the fore-paddles, which is not to be found in any porpoise, dolphin, grampus, or whale, and for want of which these creatures are so helpless when left high and dry on the shore.[ ] the structure in question is a strong bony arch, inverted and spanning across beneath the chest from one shoulder to the other. a fish-lizard, when so visiting the shore for sleep, or in the breeding season, would lie or crawl, prostrate, with its under side resting or dragging on the ground--somewhat after the manner of a turtle. [ ] it is, perhaps, hardly necessary to remark that whales are not fishes, but mammals which have undergone great change in order to adapt themselves to a marine life. their hind limbs have practically vanished, only a rudiment of them being left. it is a curious fact that this bony arch resembles the same part in those singular and problematical mammals, the echidna and the platypus, or duck-mole. the enormous magnitude and peculiar construction of the eye are highly interesting features. the expanded pupil must have allowed of the admittance of a large quantity of light, so that the creature possessed great powers of vision. the organic remains associated with fish-lizards tell us that they inhabited waters of moderate depth, such as prevails near a coast-line or among coral islands. moreover, an air-breathing creature would obviously be unable to live in "the depths of the sea;" for it would take a long time to get to the surface for a fresh supply of air. perhaps no part of the skeleton is more interesting than the curious circular series of bony plates surrounding the iris and pupil of the eye. the eyes of many fishes are defended by a bony covering consisting of two pieces; but a circle of bony overlapping plates is now only found in the eyes of turtles, tortoises, lizards, and birds, and some alligators. this elaborate apparatus must have been of some special use; the question is--what service or services did it perform? here, again, we find answers suggested by owen and buckland. it would aid, they say, in protecting the eye-ball from the waves of the sea when the creature rose to the surface, as well as from the pressure of the water when it dived down to the bottom--for even at a slight depth pressure increases, as divers know. but it appears that the ring of bony plates fulfilled a yet more important office, thereby enabling the fish-lizards to play admirably their part in the world in which they lived, and to succeed in the struggle of life; for even in those remote days there must have been, as now, a keen competition among all animals, so that the victory was to those that were best equipped. would it not be an advantage for them to have the power of seeing their finny prey whether near or far? certainly it would; and so we are told that, by bringing the plates a little nearer together, and causing them to press gently on the eye-ball, so as to make the eye more convex--that is, bulging out--a nearer object would be the better discerned. on the other hand, by relaxing this pressure, thus enlarging the aperture of the pupil and diminishing the convexity, a distant object would be focussed upon the retina. in this manner some birds alter the focus of their eyes while swooping down on their prey. what a wonderful arrangement! we often hear of people having two pairs of spectacles--with lenses of different curvature--one for reading, and the other for seeing more distant objects than a book held in the hand. but here is a creature that possessed an apparatus far more simple and effective than that supplied by the optician! dr. buckland, speaking of these "sclerotic plates," as they are called, says they show "that the enormous eye of which they formed the front was an optical instrument of varied and prodigious power, enabling the ichthyosaurus to descry its prey in the obscurity of night and in the depths of the sea." but the last expression must be taken in a limited sense (see fig. ). [illustration: fig. .--head of _ichthyosaurus platyodon_.] it might well be supposed that no record had been preserved from which we could learn anything about the nature of the skin of our fish-lizard; but even this wish has been partly fulfilled, to the delight of all geologists. certain specimens have been obtained, from the lias of england and germany, that show faithful impressions of the skin that covered the paddles. a specimen of this nature has lately been presented to the national treasure-house at south kensington by mr. montague brown. on the inner side of the paddle was a broad fin-like expansion, admirably adapted to obtain the full advantage of the stroke of the limb in swimming.[ ] [ ] mr. smith woodward informs the writer that specimens have lately been found near würtemberg, with evidence of a triangular fin on the back. plate ii. has been redrawn for this edition, to make it more in harmony with dr. fraas's discoveries. (see appendix v.) speaking of the limbs, it should be mentioned that the bones of each finger, instead of being elongated and limited in number to three in each of the five fingers, are polygonal in shape and arranged in as many as seven or eight rows, while those of each finger are exceedingly numerous. thus the whole structure forms a kind of bony pavement which must have been very supple. such a limb would be one of the most efficient and powerful swimming organs known in the whole animal kingdom. in whales the fingers of the flippers are of the usual number, namely, five. some species of fish-lizards had as many as over a hundred separate little bones in the fore-paddle. another question naturally suggests itself: were they viviparous, or did they lay eggs like crocodiles? this question seems to have been answered in favour of the first supposition; and in the following interesting manner. it not infrequently happens that entire little skeletons of very small individuals are found under the ribs of large ones. they are invariably uninjured, and of the same species as the one that encloses them, and with the head pointing in one direction. such specimens are most probably the fossilised remains of little fish-lizards, that were yet unborn when their mothers met with an untimely end (see p. ). in some cases, however, they may be young ones that were swallowed. (see appendix v.) the jaws of these hungry formidable monsters were provided with a series of formidable teeth--sometimes over two hundred in number--inserted in a long groove, and not in distinct sockets, as in the case of crocodiles. in some cases, sixty or more have been found on each side of the upper and lower jaws, giving a total of over two hundred and forty teeth! the larger teeth may be two inches or more in length. the jaws were admirably constructed on a plan that combined lightness, elasticity, and strength. instead of consisting of one piece only, they show a union of plates of bone, as in recent crocodiles. these plates are strongest and most numerous just where the greatest strength was wanted, and thinner and fewer towards the extremities of the jaw. a crocodile, sir samuel baker says, in his _wild beasts and their ways_, can bite a man in two; and no doubt our fish-lizard would have been glad to perform the same feat! but in his pre-adamite days the opportunity did not present itself. the spinal column, or backbone, with its generally concave vertebræ, must have been highly flexible, as is that of a fish, especially the long tail which the creature worked rapidly from side to side as it lashed the waters. the hollows of these concave vertebræ must have been originally filled up with fluid forming an elastic bag, or capsule. to get a clearer idea of this, take a small portion of the backbone of a boiled cod, or other "bony" fish, and you will see on pulling it to pieces, the white, jelly-like substance that fills up the hollows between the vertebræ. in this way nature provides a soft cushion between the joints, that allows of a certain amount of movement, while, at the same time, the column holds together. the backbone of a fish may not inaptly be compared to a railway train. each of the carriages represents a vertebra, and the buffers act as cushions when the train is bent in running round a curve. after all, we must learn from nature; and many of the greatest mechanical and engineering triumphs of to-day are based upon the methods used by nature in the building up and equipment of vegetable and animal forms of life. it may, perhaps, be inquired whether there is any evidence for the existence of a tail-fin, such as is shown in our illustration. to this it may be replied that the presence of such an appendage is as good as proved by a certain flattening of the vertebræ at the end of the tail, detected by owen. the direction of this flattening is from side to side, and therefore the tail-fin must have been vertical, like that of a fish. in one specimen sir richard owen has detected as many as vertebræ to the whole body. our description of the fish-lizard has, we trust, been sufficient--although not couched in the language used by men of science--to give a fair idea of its structure and habits. in conclusion, a few words may be said about the ancestry and life-history of these ancient monsters. palæontologists have good reason to believe that they were descended from some early form of land reptile. if so, they show that whales are not the first land animals that have gone back to the sea, from which so many forms of life have taken their rise. during the long mesozoic period fish-lizards played the part that whales now play in the economy of the world; and they resembled the latter, not only in general shape, but in the situation of the nostrils (near the eye), and in their teeth and long jaws. but these curious resemblances must not be interpreted to mean that whales and fish-lizards are related to each other. they only show that similar modes of life tend to produce artificial resemblances--just as some whales, in their turn, show a superficial resemblance to fishes. with regard to the particular form of reptile from which the fish-lizard may have been derived, no certain conclusion has at present been arrived at. this is chiefly from want of fuller knowledge of early forms, such as may have existed in the previous periods known as the carboniferous and trias (see appendix i.). but there are certain features in the skulls, teeth, and vertebræ that suggest a relationship with the labyrinthodonts, or primæval salamanders that flourished during the above periods, or at least from amphibians more or less closely allied to them. they cannot by any possibility be regarded as modified fishes; for fishes have gills instead of lungs. the fish-lizards played their part, and played it admirably; but their days were numbered, and the place they occupied has since been taken by a higher type--the mammal. as reptiles, they were eminently a success; but, then, they were only reptiles, and therefore were at last left behind in the struggle for existence, until finally they died out, at the end of the cretaceous period, when certain important geographical and other changes took place, helping to cause the extinction of many other strange forms of life, as we shall see later on (see p. ). they had a wide geographical range; for their remains have been discovered in arctic regions, in europe, india, ceram, north america, the east coast of africa, australia, and new zealand. in american deposits they are represented by certain toothless forms, to which the name sauranodon ("toothless lizard") has been given. these have been discovered by professor marsh, in the jurassic strata of the rocky mountains. they were eight or nine feet long, and in every other respect resembled ichthyosaurs. as we have endeavoured to indicate in our illustration, the fish-lizards flourished in seas wherein animal, and doubtless vegetable life was very abundant. any one who has collected fossils from the lias of england will have found how full it is of beautiful organic remains, such as corals, mollusca, encrinites, sea-urchins, and other echinoids, fishes, etc. the climate of this period in europe was mild and genial, or even semi-tropical. coral reefs and coral islands varied the landscape. there is just one more point of interest that ought not to be omitted; it refers to the manner in which these reptiles of the lias age met their deaths, and were thus buried up in their rocky tombs. sir charles lyell and other writers point out that the individuals found in those strata must have met with a sudden death and quick burial; for if their uncovered bodies had been left, even for a few hours, exposed to putrification and the attacks of fishes at the bottom of the sea, we should not now find their remains so completely preserved that often scarcely a single bone has been moved from its right place. what was the exact nature of this operation is at present a matter of doubt. chapter iv. the great sea-lizards and their allies. "the wonders of geology exercise every faculty of the mind--reason, memory, imagination; and though we cannot put our fossils to the question, it is something to be so aroused as to be made to put the questions to one's self."--hugh miller. the fish-lizards, described in our last chapter, were not the only predaceous monsters that haunted the seas of the great mesozoic age, or era. we must now say a few words about certain contemporary creatures that shared with them the spoils of those old seas, so teeming with life. and first among these--as being more fully known--come the long-necked sea-lizards, or plesiosaurs. the plesiosaurus was first discovered in the lias rocks of lyme-regis, in the year . it was christened by the above name, and introduced to the scientific world by the rev. mr. conybeare (afterwards dean of llandaff) and mr. (afterwards sir henry) de la beche. they gave it this name in order to distinguish it from the ichthyosaurus, and to record the fact that it was more nearly allied to the lizard than the latter.[ ] conybeare, with the assistance of de la beche, first described it in a now-classic paper read before the geological society of london, and published in the _transactions_ of that society in the year . in a later paper ( ) he gave a restoration of the entire skeleton of plesiosaurus dolichodeirus; and the accuracy of that restoration is still universally acknowledged. this fine specimen was in the possession of the duke of buckingham, who kindly placed it at the disposal of dr. buckland, for a time, that it might be properly described and investigated. [ ] the name is derived from two greek words--_plesios_, near, or allied to, and _sauros_, a lizard. a glance at our illustration, plate iii., will show that this strange creature was not inaptly compared at the time to a snake threaded through the body of a turtle. dr. buckland truly observes that the discovery of this genus forms one of the most important additions that geology has made to comparative anatomy. "it is of the plesiosaurus," says that graphic author, in his _bridgewater treatise_, "that cuvier asserts the structure to have been the most heteroclite, and its characters altogether the most monstrous that have been yet found amid the ruins of a former world. to the head of a lizard it united the teeth of a crocodile; a neck of enormous length, resembling the body of a serpent; a trunk and tail having the proportions of an ordinary quadruped; the ribs of a chameleon, and the paddles of a whale! such are the strange combinations of form and structure in the plesiosaurus--a genus, the remains of which, after interment for thousands of years amidst the wreck of millions of extinct inhabitants of the ancient earth, are at length recalled to light by the researches of the geologist, and submitted to our examination in nearly as perfect a state as the bones of species that are now existing upon the earth." perhaps the best way in which we can gain a clear idea of the general characters of a long-necked sea-lizard, as we may call our plesiosaurus, is by comparing it with the fish-lizard, described in the last chapter. its long neck and small head are the most conspicuous features. then we notice the short tail. but if we compare the paddles of these two extinct forms of life, we notice at once certain important differences. in the fish-lizard the bone of the arm was very short, while all the bones of the fore-arm and fingers were modified into little many-sided bodies, and so articulated together as to make the whole limb, or paddle, a solid yet flexible structure. in the long-necked sea-lizard, however, we find a long arm-bone with a club-like shape; and the two bones of the fore-arm are seen to be longer than in the fish-lizard. but a still greater difference shows itself in the bones of the finger, as we look at a fossilised skeleton (or a drawing of one); for the fingers are long and slender, like those of ordinary reptiles. there are only five fingers, and each finger is quite distinct from the others. this is the reason why the plesiosaur was considered to depart less from the type of an ordinary reptile, and so received its name. other remarkable differences present themselves in the shoulders and haunches, but these need not be considered here. the species shown in fig. had rather a large head. it is obvious that such a long slender neck as these creatures had could not have supported a large head, like that of the fish-lizard. consequently, we find a striking contrast in the skulls of the two forms. that of the plesiosaur was short and stout, and therefore such as could easily be supported, as well as rapidly moved about by the long slender neck. thus we find another simple illustration of the "law of correlation," alluded to on p. . the teeth were set in distinct sockets, as they are in crocodiles, to which animals there are also points of resemblance, in the backbone, ribs, and skull. fig. shows three different types of lower jaws of plesiosaurs. the one marked c belongs to plesiosaurus dolichodeirus, the species represented in our plate. there were no bony plates in the eye. professor owen thinks that they were long-lived. the skin was probably smooth, like that of a porpoise. [illustration: plate iii. pterodactyls. long-necked sea-lizard. cuttle-fish or belemnite. _plesiosaurus dolichodeirus._ length feet.] [illustration: fig. .--mandibles of fish-lizards. a, _peloneustes philarchus_ (seeley); from the oxford clay. b, _thaumatosaurus indicus_ (lydekker); upper jurassic of india. c, _plesiosaurus aolichodirus_ (conybeare); from the lower lias, lyme regis.] the visitor to the geological collection at south kensington will find a splendid series of the fossilised remains of long-necked sea-lizards. they were mostly obtained from the lias formation of street in somersetshire, lyme-regis in dorset, and whitby in yorkshire. those from the lias are mostly small, about eight to ten feet in length. but in the rocks of the cretaceous period, which was later, are found larger specimens. there is a cast of a very fine specimen from the upper lias on the wall of the east corridor (no. on plan) of the geological galleries at south kensington, which is twenty-two feet long. but some of the cretaceous forms, both in europe and america, attained a length of forty feet, and had vertebræ six inches in diameter. the bodies of the vertebræ, or "cup-bones," are either flat or slightly concave, showing that the backbone as a whole was less flexible than in the fish-lizards. [illustration: fig. .--_plesiosaurus macrocephalus._] it may be mentioned here that mr. smith woodward, of the natural history museum, recently showed the writer a fossil plesiosaur that is being set up in the formatore's shop, in the same manner that a recent skeleton might be. in this, and many other ways, the guardians of the national treasure-house are endeavouring to make the collection intelligible and interesting to the general public. specimens of extinct animals thus set up, give one a much better idea than when the bones are all lying huddled together on a slab of rock. but it is not always possible to get the bones entirely out of their rocky bed, or matrix. great credit is due to mr. alfred n. leeds, of eyebury, who has disinterred the separate bones of many distinct skeletons of plesiosaurs from oxford clay strata near peterborough. it will be remembered that the long and powerful tail of the fish-lizard was its principal organ of propulsion through the water; and that, consequently, the paddles only played a secondary part. they were small, but amply large enough for the work they had to perform. but our long-necked sea-lizards possessed very short tails. what, then, was the consequence? obviously that the paddles had all the more work to do. they were the chief swimming organs. the vertebræ of this short tail show that it probably was highly flexible, and could move rapidly from side to side; but, for all that, its use as a propeller would not be of much importance. we see now why the paddles are so long and powerful, like two pairs of great oars, one pair on each side of the body. in a fossil skeleton you will notice the flattened shape of the arm-bone (or humerus), and of the thigh-bone (or femur). this gave breadth to the paddles, and made them more efficient as swimming organs. they give no indication of having carried even such imperfect claws as those of turtles and seals, and therefore we may conclude that the plesiosaur was far more at home in the water than on land, and it seems probable that progression on land was impossible. the tail was probably useful as a rudder, to steer the animal when swimming on the surface, and to elevate or depress it in ascending and descending through the water. like the fish-lizard, this creature was an air-breather, and therefore was obliged occasionally to visit the surface for fresh supplies of air. but probably it possessed the power of compressing air within its lungs, so that the frequency of its visits to the surface would not be very great. from the long neck and head, situated so far away from the paddles, as well as for other reasons, it may be concluded that this creature was a rapid swimmer, as was the ichthyosaurus. although of considerable size, it probably had to seek its food, as well as its safety, chiefly by artifice and concealment. the fish-lizard, its contemporary, must have been a formidable rival and a dangerous enemy, whom to attack would be unadvisable. speaking of the habits of the long-necked sea-lizard, mr. conybeare, in his second paper, already alluded to, says, "that it was aquatic, is evident from the form of its paddles; that it was marine, is almost equally so, from the remains with which it is universally associated; that it may occasionally have visited the shore, the resemblance of its extremities to those of the turtle may lead us to conjecture; its motion, however, must have been very awkward on land; its long neck must have impeded its progress through the water, presenting a striking contrast to the organisation which so admirably fits the ichthyosaurus to cut through the waves. "may it not therefore be concluded (since, in addition to these circumstances, its respiration must have required frequent access of air) that it swam upon or near the surface, arching back its long neck like the swan, occasionally darting it down at the fish which happened to float within its reach? it may, perhaps, have lurked in shoal-water along the coast, concealed among the sea-weed, and, raising its nostrils to a level with the surface from a considerable depth, may have found a secure retreat from the assaults of dangerous enemies; while the length and flexibility of its neck may have compensated for the want of strength in its jaws and its incapacity for swift motion through the water, by the suddenness and agility of the attack which they enabled it to make on every animal fitted for its prey, which came within its extensive sweep." more than twenty species of long-necked sea-lizards are known to geologists. professor owen, in his great work on _british fossil reptiles_, when describing the huge plesiosaurus dolichodeirus from dorset, suggests that the carcase of this monster, after it sank to the bottom of the sea, was preyed upon by some carnivorous animal (perhaps sharks). it seems, he says, as if a bite of the neck had pulled out of place the eighth to the twelfth vertebræ. those at the base of the neck are scattered and dispersed as if through more "tugging and riving." so with regard to its body, probably some hungry creature had a grip of the spine near the middle of the back, and pulled all the succeeding vertebræ in the region of the hind limbs. thus we get a little glimpse of scenes of violence that took place at the bottom of the bright sunny seas of the period when the clays and limestones of the lias rocks were being deposited in the region of lyme-regis. as time went on, these curious reptiles increased in size, until, in the period when our english chalk was being formed (cretaceous period), they reached their highest point (see p. ). after that they became extinct--whether slowly or somewhat suddenly we cannot tell. until more is known of the ancient life of the earth, it will not be possible to say with certainty what were the nearest relations of the long-necked sea-lizards. they first appear in the strata of the new red sandstone, which is below the lias. certain little reptiles, about three feet long, from the former rocks, known as neusticosaurus and lariosaurus, seem to be rather closely related to the creatures we are now considering, and to connect them with another group, namely, the pliosaurs. they were partly terrestrial and partly aquatic; but it is not easy to say whether their limbs had been converted into true paddles or not. at any rate, there is every reason to believe that the long-necked sea-lizards were descended from an earlier form of land reptile. they gradually underwent considerable modifications, in order to adapt themselves to an aquatic life. we noticed that the same conclusion has been arrived at with regard to the fish-lizards. both these extinct groups, therefore, present an interesting analogy to whales, which are now considered to have been derived, by a like series of changes, from mammals that once walked the earth. the plesiosaur presents, on the one hand, points of resemblance to turtles and lizards,--on the other hand, to crocodiles, whales, and, according to some authorities, even the strange ornithorhynchus. but it will be very long before its ancestry can be made known. in the mean time, we must put it in a place somewhere near the fish-lizards, and leave posterity to complete what has at present only been begun. it must, however, be borne in mind that some of the above resemblances are purely accidental, and not such as point to relationship. because their flippers are like those of a whale, it does not mean that plesiosaurs are related to modern whales. it only means that similar habits tend to produce accidental resemblances--just as the whales and porpoises, in their turn, resemble fishes. to make torpedoes go rapidly through the water, inventors have given them a fish-like shape;--in the same way the early forms of mammals, from which whales are descended, gradually adapted themselves to a life in the water, and so became modified to some extent to the shapes of fishes. the pliosaurs, above mentioned, are evidently relations, but with short necks instead of long ones. they had enormous heads and thick necks. fine specimens of their huge jaws, paddle-bones, etc., may be seen at the end of the reptile-gallery at cromwell road. one of the skulls exhibited there is nearly six feet long, while a hind paddle measures upwards of six and a half feet in length, of which thirty-seven inches is taken up by the thigh-bone alone. the teeth at the end of the jaws are truly enormous. one tooth, from a deposit known as the kimmeridge clay, is nearly a foot long from the tip of the crown to the base of the root. in some, the two jaw-bones of the lower jaw are partly united, as in the sperm-whale or cachalot. creatures so armed must have been very destructive. chapter v. the dragons of old time--dinosaurs. "what we know is but little; what we do not know is immense."--la place. was there ever an age of dragons? tradition says there was; but there is every reason to believe that the fierce and blood-thirsty creatures, of which such a variety present themselves, are but creations of the imagination,--useful in their way, no doubt, as pointing a moral or adorning a tale, but, nevertheless, wholly without foundation in fact. the dragon figures in the earliest traditions of the human race, and crops up again in full force in european mediæval or even late romance. in ancient egyptian mythology, horus, the son of isis, slays the evil dragon. in greece, the infant hercules, while yet in his cradle, strangles deadly snakes; and perseus, after engaging in fierce struggle with the sea-monster, slays it, and rescues andromeda from a cruel death. in england, we have the heroic legend of st. george and the dragon depicted on our sovereigns. but it is easy to see a common purpose running through these legends. they are considered by many to be solar myths, and have a moral purpose. the dragons or snakes are emblems of darkness and evil; the heroes emblems of light, and so of good. the triumph of good over evil is the theme they were intended to illustrate. the dragons, then, are clearly products of the imagination, based, no doubt, on the huge and uncouth reptiles of the present human era, such as crocodiles, pythons, and such creatures. amidst much diversity there is yet a strange similarity in the dragons that figure in the folk-lore of eastern and western peoples. probably our european traditions were brought by the tribes which, wave after wave, poured in from central asia. they are, for the most part, unnatural beasts, breathing out fire, and often endowed with wings, while at the same time possessing limbs ending in cruel claws, fitted for clutching their unfortunate victims. the wings seem, to say the least, very much in the way. poisonous fangs, claws, scaly armour, and a long pointed tail were all very well,--but wings are hardly wanted, unless to add one more element of mystery or terror. some, however, are devoid of wings: the imperial japanese dragons showing no sign of such appendages. the temple bar griffin is a grim example of a winged monster. nevertheless, in spite of all the manifest absurdities of the dragons of various nations and times, geology reveals to us that there once lived upon this earth reptiles so great and uncouth that we can think of no other but the time-honoured word "dragon" to convey briefly the slightest idea of their monstrous forms and characters. so there is some truth in dragons, after all. but then we must make this important reservation--viz. that the days of these dragons were long before the human period; they flourished in one of those dim geological ages of which the rocks around us bear ample records. it is a strange fact that human fancy should have, in some cases at least, created monsters not very unlike some of those antediluvian animals that have, during the present century, been discovered in various parts of europe and america. some unreasonable persons will have it that certain monstrous reptiles of the mesozoic era, about to be described, must have somehow managed to survive into the human period, and so have suggested to early races of men the dragons to which we have alluded. but there is no need for this untenable supposition. by a free blending together of ideas culled from living types of animals it would be very easy to construct no small variety of dragons; and so we may believe this is what the ancients did. having said so much of dragons in general, let us proceed to consider those both possible and real monsters revealed of late years by the researches of geologists. for this purpose we shall devote the present and two following chapters to the consideration of a great and wonderful group of fossil reptiles known as dinosaurs. the strange fish-lizards and sea-lizards previously described were the geological contemporaries of a host of reptiles, now mostly extinct, which inhabited both the lands and waters of those periods known as the triassic, jurassic, and cretaceous, which taken together represent the great mesozoic, formerly called the secondary, era. the announcement by baron cuvier--the illustrious founder of palæontology--that there was a period when our planet was inhabited by reptiles of appalling magnitude, with many of the features of modern quadrupeds, was of so novel and startling a character as to require the prestige of even his name to obtain for it any degree of credence. but subsequent discoveries have fully confirmed the truth of his belief, and the "age of reptiles" is no longer considered fabulous. this expression was first used by dr. mantell as the title of a paper published in the _edinburgh philosophical journal_ in , and serves to remind us that reptilian forms of life were once the ruling class among animals. the dinosaurs are an extinct order comprising the largest terrestrial and semi-aquatic reptiles that ever lived; and while some of them in a general way resembled crocodiles, others show in the bony structures they have left behind a very remarkable and interesting resemblance to birds of the ostrich tribe. this resemblance shows itself in the pelvis, or bony arch with which the hind limbs are connected in vertebrate or backboned animals, and in the limbs themselves. this curious fact, first brought into notice by professor huxley, has been variously interpreted by anatomists; some concluding, with professor huxley, that birds are descended from dinosaurs; while others, with professor owen, consider the resemblance accidental, and in no way implying relationship. huxley has proposed the name ornithoscelida, or bird-legged, for these remarkable reptiles. dinosaurs must have formerly inhabited a large part of the primæval world; for their remains are found, not only in europe, but in africa, india, america, and even in australia; and the geologist finds that they reigned supreme on the earth throughout the whole of the great mesozoic era. their bodies were, in some cases, defended by a formidable coat of armour, consisting of bony plates and spines, as illustrated by the case of scelidosaurus (p. ), thus giving them a decidedly dragon-like appearance. the vertebræ, or bony segments of the backbone, generally have their centra hollow on both sides, as in the ichthyosaurus; but in the neck and tail they are not unfrequently hollow on one side and convex on the other. in some of the largest forms the vertebræ are excavated into hollow chambers. this is apparently for the sake of lightness; for a very large animal with heavy solid bones would find it difficult to move freely. in this way strength was combined with lightness. all the dinosaurs had four limbs, and in many cases the hind pair were very large compared to the fore limbs. they varied enormously in size, as well as in appearance. thus certain of the smaller families were only two feet long and lightly built; while others were truly colossal in size, far out-rivalling our modern rhinoceroses and elephants. the limbs of cetiosaurus, for example, or of stegosaurus, remind us strikingly of those of elephants. the celebrated von meyer was so struck with this likeness that he proposed the name pachypoda for them, which means thick-footed. professor owen opposed this name; for it was misleading, and only applied to a few of them. he therefore proposed the name we have already been using, viz. dinosauria,[ ] and this name has been generally retained. we are thus led to connect them with lizards and crocodiles, rather than with birds or quadrupeds. the strange and curiously mixed characters of the old-fashioned reptiles is forcibly illustrated by these differences of opinion among leading naturalists. professor seeley, another living authority, refuses to consider them as reptiles, at least in the ordinary sense of the word. [ ] greek--_deinos_, terrible; _sauros_, lizard. extinct forms of life are often so very different to the creatures inhabiting the world of to-day, that naturalists find it a hard task to assign them their places in the animal kingdom. the classes, orders, and families under which living forms are grouped are often found inadequate for the purpose, so much so that new orders and new families require to be made for them; and then it is often quite impossible to determine the relations of these new groups to the old ones we are accustomed to. dinosaurs offer a good example of this difficulty. were they related to ancient crocodiles? no one can say for certain; but it is quite possible, and even probable. again, did certain long-legged dinosaurs eventually give rise by evolution to the running birds, ostriches, emeus, etc.? this, although supported by weighty authority, is a matter of speculation: we ought to be very careful in accepting such conclusions. it may perhaps be safer to look upon the ancestry of birds as one of those problems on which the oracle of science cannot at present declare itself. various attempts have been made to classify dinosaurs, and arrange them in family groups; but, considering our imperfect knowledge, it will be wise to regard all such attempts as purely temporary and provisional, although in some ways convenient. professor marsh, of yale college, u.s., whose wonderful discoveries in the far west have attracted universal attention, has grouped the dinosaurs into five sub-orders. it will, however, be sufficient for our purpose if we follow certain english authorities who divide them into three groups--taking the names given by professor marsh, only running together some which he would separate. we shall first consider the very interesting and huge forms included in his sub-order the sauropoda, or lizard-footed dinosaurs. various parts of the skeletons, such as vertebræ, leg-bones, etc., of these cumbrous beasts have long been known in this country; but professor marsh was the first person to discover a complete skeleton. we shall, therefore, now turn our attention to the bony framework of the huge brontosaurus (fig. ), a vegetable-feeding lizard. but it will be necessary to completely lay aside all our previous notions taken from lizards of the present day, with their short legs and snake-like scaly bodies, before we can come to any fair conclusion with regard to this monstrous beast. it was nearly sixty feet long, and probably when alive weighed more than twenty tons! that it was a stupid, slow-moving reptile, may be inferred from its very small brain and slender spinal cord. by taking casts of the brain-cavities in the skulls of extinct animals, anatomists can obtain a very good idea of the nature and capacity of their brains; and in this way important evidence is obtained, and such as helps to throw light upon their habits and general intelligence. no bony plates or spines have been discovered with the remains of this monster; so that we are driven to conclude that it was wholly without armour: and, moreover, there seem to be no signs of offensive weapons of any kind. professor marsh concludes that it was more or less amphibious in its habits, and that it fed upon aquatic plants and other succulent vegetation. its remains, he says, are generally found in localities where the animal had evidently become mired, just as cattle at the present day sometimes become hopelessly fixed in a swampy place on the margin of a lake or river (see p. ). each track made by the creature in walking occupied one square yard in extent! [illustration: fig. .--restored skeleton of _brontosaurus excelsus_. (after marsh.)] the remarkably small head is one of the most striking features of this dinosaur, and presents a curious contrast to the large and formidable skulls possessed by some other forms to be described further on. but it is clear that no animal with such a long neck as this creature had could have borne the weight of a heavy skull. short thick necks and heavy skulls always go together. indeed, the weight of the long neck itself would have been serious had it not been for the fact that the vertebræ in this part of the skeleton, and as far as the region of the tail, have large cavities in the sides of the centra. this cavernous structure of the vertebræ gradually decreases towards the tail. the cavities communicated with a series of internal cavities which give a kind of honeycombed structure to the whole vertebra. this arrangement affords a combination of strength and lightness in the massive supports required for the huge ribs, limbs, and muscles, such as could not have been provided by any other plan. (see fig. .) [illustration: fig. .--neck vertebræ of _brontosaurus_. . front view. . back view.] [illustration: plate iv. a gigantic dinosaur, brontosaurus excelsus. length nearly feet.] the body of the brontosaur was comparatively short, with a fairly large paunch (see restoration, plate iv.). the legs and feet were strong and massive, and the limb-bones solid. as if partly in order to balance the neck, we find a long and powerful tail, in which the vertebræ are nearly all solid. in most dinosaurs the fore limbs are small compared to the hind limbs--_e.g._ megalosaurus, iguanodon, and scelidosaurus,--but here we find them unusually large. in this case, then, it is hardly possible that the creature walked upon its hind legs, as many of the dinosaurs did. but, at the same time, we may believe that occasionally it assumed a more erect position; and may not the light hollowed structure of the vertebræ in the fore part of the body, already alluded to, have imparted such lightness as made it possible for the creature to assume such attitudes? there can be little doubt but that many other fierce and formidable dinosaurs were living at the same time and in the same region with brontosaurus, whose remains are found in the jurassic rocks of colorado (atlantosaurus beds). how this apparently helpless and awkward animal escaped in the struggle for existence it is not easy to conjecture; but since there is reason to believe it was more or less at home in the water, and could use its powerful tail in swimming, we may perhaps find a way out of the difficulty by supposing that, when alarmed by dangerous flesh-eating foes, it took to the water, and found discretion to be the better part of valour. although apparently stupid, the brontosaur probably possessed a good deal of cunning, and we can fancy it stretching its long neck above reeds, ferns, and cycads to get a view of the approaching enemy. the sauropoda, or lizard-footed dinosaurs, show in many ways a decided approach to a simple or generalised crocodile; so much so, that professor cope is inclined to include crocodiles and sauropodous dinosaurs in the same order. still, there are important differences in other members of this sub-order. unfortunately, our knowledge is at present rather limited, owing to the want of complete skeletons. vertebræ, limb-bones, skulls, and teeth have all been discovered through the zeal and energy of professor marsh and his comrades, in the far west of america, as well as by the researches of english geologists, assisted by the labours of many ardent collectors of fossils, in this country. some of these may now be briefly considered. in plate v. we have endeavoured to give some idea of a huge thigh-bone (femur) belonging to the truly gigantic dinosaur called atlantosaurus. it is six feet two inches long, and a cast of it may be seen in the fossil reptile gallery of the british museum of natural history (wall-case no. ). it should be mentioned, however, that the original specimen is partly restored, so that its exact length to an inch or so is not quite certain. in our illustration it is shown to be a little taller, when placed upright, than a full-grown man. professor marsh, the fortunate discoverer of this wonderful bone, calculates that the atlantosaurus must have attained a length of over eighty feet! and, assuming that it walked upon its hind feet, a height of thirty feet! it doubtless fed upon the luxuriant foliage of the sub-tropical forests, portions of which are preserved with its remains. besides this thigh-bone, professor marsh has procured specimens of vertebræ from the different parts of the vertebral column; but no skull or teeth. the vertebræ are hollowed out much in the same way as those of brontosaurus. the fore limbs were large, as in the latter animal; and the extremities of the limbs were provided with claws. taking all present evidence, it appears that the atlantosaurus bore a general resemblance to its smaller contemporary. we can therefore form a fairly good idea of its aspect and proportions. the same jurassic strata from the rocky mountains have yielded remains of another big dinosaur, belonging to the same family. this genus, which has been named the apatosaurus, is represented by a nearly complete skeleton, in the yale college museum; and is fortunately in an excellent state of preservation. another species, of smaller size, though not so complete, adorns the same collection. this was about thirty feet long, and is known as apatosaurus grandis. [illustration: plate v. thigh-bone of the largest of the dinosaurs, atlantosaurus. from a cast in the natural history museum. length feet inches.] morosaurus, another important genus, is known from a large number of individuals discovered in the now famous atlantosaurus beds of colorado, including one nearly complete skeleton. the head of this creature was small; the neck elongated; and the vertebræ of the neck are lightened by deep cavities in their centra, similar to those in birds of flight. the tail, also, was long. when alive, this dinosaur was about forty feet in length. it probably walked on all fours; and in many other respects was very unlike a typical dinosaur. the brain was small, and it must have been sluggish in all its movements. the nearly complete remains of morosaurus grandis were found together in a very good state of preservation in wyoming, and many of the bones lay just in their natural positions. diplodocus, of which several incomplete specimens have been discovered, was intermediate in size between atlantosaurus and morosaurus, and may have reached when living, a length of forty or fifty feet. its skull was of moderate size, with slender jaws. the teeth were weaker than those of any other known dinosaur, and entirely confined to the front of the jaws. professor marsh concludes from the teeth that diplodocus was herbivorous, feeding on succulent vegetation, and that it probably led an aquatic life. fig. shows its skull. the remains of this interesting dinosaur (brontosaurus), which in several ways differs from other members of the "lizard-footed" group, were found in upper jurassic beds, near cañon city, colorado. a second smaller species was also discovered near morrison, colorado. all the remains lay in the atlantosaurus beds. these strata--the tomb in which nature has buried up so many of her dragons of old time--can be traced for several hundred miles on the flanks of the rocky mountains, and are always to be known by the bones they contain. they lie above the triassic strata and just below the sandstone of the dakota group. some have regarded them as of cretaceous age; but, judging from their fossils, there can be but little doubt that they were deposited during the jurassic period--probably in an old estuary. they consist of shale and sandstone. besides the numerous dinosaurs, professor marsh's colleagues have found abundant remains of crocodiles, tortoises, and fishes, with one pterodactyl, a flying reptile (see chap. viii.), and several small marsupials. the wonderful collection of american jurassic dinosaurs in the museum of yale college includes the remains of several hundred individuals, many of them in excellent preservation, and has afforded to professor marsh the material for his classification already alluded to. [illustration: fig. .--head of _diplodocus_. . side view. . front view.] english dinosaurs of the lizard-footed group. unfortunately, there are at present no complete skeletons known of english dinosaurs related to the american forms above described. but, since the english fossils were first in evidence by many years, and marsh's discoveries have confirmed in a remarkable way conclusions drawn by owen, huxley, hulke, and seeley, and others from materials that were rather fragmentary, it may be worth while to give some account of these remains and the interpretations they have received. dr. buckland, in his _bridgewater treatise_, , referred to a limb-bone in the oxford museum, from the great oolite formation near woodstock, which was examined by cuvier, and pronounced to have once belonged to a whale; also a very large rib, which seemed whale-like. in professor owen, when collecting materials for his famous _report on the fossil reptiles of great britain_, inspected this remarkable limb-bone, and could not match it with any bones known among the whale tribe; and yet its structure, where exposed, was like that of the long bone (humerus) of the paddle of a whale. later on, he abandoned the idea that it once belonged to a whale, and it was thought that the extinct animal in question might have been a reptile of the crocodilean order. in time, a fine series of limb-bones and vertebræ was added to the oxford museum by professor phillips (dr. buckland's successor at oxford), who pronounced them to be dinosaurian. the name "cetiosaurus"[ ] (or whale-lizard), originally given by owen, was unfortunate, because there is really nothing whale-like about it, except a certain coarse texture of some of the bones. [ ] greek--_ketion_, whale; _sauros_, lizard. in dr. buckland announced the discovery of another limb-bone (a femur), which owen referred to cetiosaurus; it was four feet three inches in length. between and , however, a considerable portion of a skeleton was discovered in the same formation at kirtlington station, near oxford. these remains were the subject of careful examination by professors owen and phillips. the femur this time was five feet four inches long. their studies threw much light on the nature and habits of cetiosaurus. although showing in many ways an approach to the crocodile type of reptile, yet it was perceived from the nature of the limbs that they were better fitted for walking on land than are those of a crocodile, with its sprawling limbs. still, professor owen was careful to point out that the vertebræ of its long tail indicate suitability as a powerful swimming organ, and concluded that the creature was more aquatic than terrestrial in its habits. plaster casts of the limb-bones may be seen at the british museum of natural history, side by side with the huge atlantosaurus cast sent by professor marsh. the kimmeridge clay of weymouth has yielded a huge arm-bone (or humerus), nearly five feet long; and from wealden strata of sussex and the isle of wight vertebræ have been collected. altogether we have remains of cetiosaurus from at least half a dozen counties. unfortunately, no specimen of a skull has yet been found, and only two or three small and incomplete teeth, which may possibly have belonged to some other animal. professor owen estimated the length of the trunk and tail of the creature to have been thirty-five or thirty-six feet; but in the absence of further evidence it was not possible to form any conclusion as to its total length. it is evident that cetiosaurus was closely allied to the american brontosaurus (p. ); and so these earlier english discoveries have gained much in interest from the light thrown upon them by professor marsh's huge saurian. another english saurian of this group was the ornithopsis, from wealden strata in the isle of wight, which has been the subject of careful study by mr. hulke and professor seeley. their conclusions, based on the examination of separate portions of the skeleton (such as vertebræ), have been singularly confirmed by the discovery of brontosaurus. in ornithopsis the vertebræ of the neck and back, though of great size, were remarkably light, and yet of great strength. one of the vertebræ of the back had a body, or centrum, ten inches long. hoplosaurus and pelosaurus were evidently reptiles closely allied to the above types; but at present are so imperfectly known that we need not consider them here. chapter vi. dinosaurs (_continued_). "fossils have been eloquently and appropriately termed 'medals of creation.'"--dr. mantell. when any tribe of plants or animals becomes very flourishing, and spreads over the face of the earth, occupying regions far apart from one another, where the geographical and other conditions, such as climate, are unlike, its members will inevitably develop considerable differences among themselves. during the great mesozoic period, dinosaurs spread over a large part of the world; they became very numerous and powerful. just as the birds and beasts (quadrupeds) of to-day show an almost endless variety, according to the circumstances in which they are placed, so that great and powerful order of reptiles we are now considering ran riot, and gave rise to a variety of forms, or types. those described in the last chapter were heavy, slow-moving dinosaurs, of great proportions, and were all herbivorous creatures, apparently without weapons of offence or defence. the group theropoda, or "beast-footed" dinosaurs, that partly form the subject of the present chapter, were all flesh-eating animals; and, as we shall discover from their fossilised remains, were of less size, and led active lives. in fact, they acted in their day the part played by lions and tigers to-day. in the year that keen observer and original thinker, the rev. dr. buckland, described to the geological society of london some remains of a very strange and formidable reptile found in the limestone of stonesfield, near woodstock (about twelve miles from oxford). this rock, known as "stonesfield slate" from its property of splitting up into thin layers, has long been celebrated for its fossil remains, and from it have also been obtained the bones of some early mammals. it is a member of the lower oolitic group. the portions of skeleton originally discovered consisted of part of a lower jaw, with teeth, a thigh bone (femur), a series of vertebræ of the trunk, a few ribs, and some other fragments. the name megalosaurus,[ ] or "great lizard," suggested itself both to dr. buckland and baron cuvier, because it was evident from the size of the bones that the creature must have been very big. it is true these bones were not found together in one spot; but professor owen came to the conclusion that they all belonged to the same species. [ ] greek--_megas_, great; _sauros_, lizard. no entire skeleton of the megalosaur has ever been found, but there was enough material to enable dr. buckland, professor owen, and professor phillips to form a very fair idea of its general structure. it should be mentioned here that dr. mantell, the enthusiastic geologist to whose labours palæontologists are greatly indebted, had previously discovered similar teeth and bones in the wealden strata of tilgate forest. sherborne, in dorset, is another locality which has yielded a fine specimen of parts of both jaws with teeth. a cast of this may be seen in the geological collection at south kensington. it was found in the inferior oolite (wall-case iv.); the original specimen lies in the museum of sherborne college. remains of megalosaurus have also been found at the following places: lyme-regis and watchet (in the lias); near bridport (in inferior oolite); enslow bridge (upper part of the great oolite and forest marble beds); weymouth (in oxford clay); cowley and dry sandford (in the coral rag); malton in yorkshire (in coralline oolite); also in normandy. they have also been found in wealden strata. the portion of a lower jaw in the oxford museum is twelve inches long, with a row of nine teeth, or sockets for teeth. the structure of the teeth leaves no doubt as to the carnivorous habits of the creature. with a length of perhaps thirty feet, capable of free and rapid movement on land, with strong hind limbs, short head, with long pointed teeth, and formidable claws to its feet, the megalosaur must have been without a rival among the carnivorous reptiles on this side of the world. it probably walked for the most part on its hind legs, as depicted in our illustration, and professors huxley and owen, on examining the bones in the oxford museum, were much impressed with the bird-like character of some parts of the skeleton, showing an approach to the ostrich type. the form of the teeth, as pointed out by dr. buckland, exhibits a remarkable combination of contrivances. when young and first protruding above the gum, the apex of the tooth presented a double cutting edge of serrated enamel; but as it advanced in growth its direction was turned backwards in the form of a pruning knife, and the enamelled sawing edge was continued downwards to the base of the inner and cutting side, but became thicker on the other side, obtaining additional strength when it was no longer needed as a cutting instrument (fig. ). [illustration: fig. .--lower jaw-bone of megalosaurus, with teeth.] the genus megalosaurus--now rendered classic through the labours of professors buckland, phillips, and owen--may be regarded as the type of the carnivorous dinosaurs; and it affords an excellent and instructive instance of the gradual restoration of the skeleton of a new monster from more or less fragmentary remains. certain very excusable errors were at first made in the restoration, but these have since been rectified by a comparison with the allied american forms, such as allosaurus, of which nearly entire skeletons have of late been discovered in strata of jurassic age--in fact, the same rock in colorado as that in which the huge atlantosaurus bones lay hid. the accompanying woodcut (fig. ) shows how the skeleton has been restored in the light of these later discoveries of professor marsh. the large bones of the limbs of these formidable flesh-eating monsters were hollow, and many of the vertebræ, as well as some of those of the feet, contained cavities, or were otherwise lightened in order to give the creature a greater power of rapid movement. [illustration: fig. .--skeleton of megalosaurus, restored. (after meyer.)] it is not very difficult to imagine a megalosaur lying in wait for his prey (perhaps a slender, harmless little mammal of the ant-eater type) with his hind limbs bent under his body, so as to bring the heels to the ground, and then with one terrific bound from those long legs springing on to the prey, and holding the mammal tight in its clawed fore limbs, as a cat might hold a mouse. then the sabre-like teeth would be brought into action by the powerful jaws, and soon the flesh and bones of the victim would be gone! (see plate vi.) [illustration: plate vi. a carnivorous dinosaur, megalosaurus bucklandi. length about feet.] as we remarked before, the carnivorous dinosaurs were the lions and tigers of the mesozoic era, and, what with small mammals and numerous reptiles of those days, it would seem that they were not limited in their choice of diet. it is a question not yet decided whether dinosaurs laid eggs as most modern reptiles do, or were viviparous like quadrupeds; but professor marsh thinks there are reasons for the latter supposition. during the early part of the mesozoic era, at the period known as the triassic (new red sandstone), dinosaurs flourished vigorously in america, developing a great variety of forms and sizes. although but few of their bones have as yet been discovered in those rocks, they have left behind unmistakable evidence of their presence in the well-known footprints and other impressions upon the shores of the waters which they frequented.[ ] the triassic sandstone of the connecticut valley has long been famous for its fossil footprints, especially the so-called "bird-tracks," which are generally supposed to have been made by birds, the tracks of which they certainly appear to resemble. but a careful investigation of nearly all the specimens yet discovered has convinced professor marsh that these fossil impressions were not made by birds (see fig. ). most of the three-toed tracks, he thinks, were made by dinosaurs, who usually walked upon their hind feet alone, and only occasionally put to the ground their small fore limbs. he has detected impressions of the latter in connection with nearly all the larger tracks of the hind limbs. these double impressions are just such as dinosaurs would make; and, since the only characteristic bones yet found in the same rocks belong to this order of reptiles, it is but fair to attribute all these footprints to dinosaurs, even where no impressions of fore feet have been detected, _until_ some evidence of birds is forthcoming. the size of some of these impressions, as well as the length of stride they indicate, is against the idea of their having been made by birds. some of them, for instance, are twenty inches in length, and four or five feet apart! the foot of the african ostrich is but ten inches long, so we must fall back on the dinosaurs for an explanation. however, it is quite possible that some of the smaller impressions were made by birds. [ ] since the above was written, professor marsh has described, in _the american journal of science_ for june, , several more or less complete skeletons of triassic dinosaurs, lately found, and now in the yale college museum. this is an important discovery. [illustration: fig. .--portion of a slab of new red sandstone, from turner's falls, massachusetts, u.s., covered with numerous tracks, probably of dinosaurs. this specimen is now in the natural history museum. the separate tracks are indicated by the numbers. (after hitchcock.)] there is at south kensington a fine series of these and other specimens of fossil footprints (gallery no. xi., wall-cases - ). the surface of one large slab in the geological collection is eight feet by six feet, and bears upwards of seventy distinct impressions disposed in several tracks, as shown in fig. . the lines were added by dr. hitchcock, who has published full descriptions in order to show the direction and disposition of the tracks. [illustration: fig. .--portion of a slab, with tracks. (after hitchcock.)] in a presidential address to the geological society, sir charles lyell, speaking of the connecticut sandstone and its impressions, said, "when i first examined these strata of slate and sandstone near jersey city, in company with mr. redfield, i saw at once from the ripple-marked surface of the slabs, from the casts of cracks, the marks of rain-drops, and the embedded fragments of drift-wood, that these beds had been formed precisely under circumstances most favourable for the reception of impressions of the feet of animals walking between high and low water. in the prolongation of the same beds in the valley of connecticut, there have been found, according to professor hitchcock, the footprints of no less than thirty-two species of bipeds, and twelve of quadrupeds. they have been observed in more than twenty localities, which are scattered over an area of nearly eighty miles from north to south, in the states of massachusetts and connecticut. after visiting several of these places, i entertained no doubt that the sand and mud were deposited on an area which was slowly subsiding all the while, so that at some points a thickness of more than a thousand feet of superimposed strata had accumulated in very shallow water, the footprints being repeated at various intervals on the surface of the mud throughout the entire series of superimposed beds." when sir charles lyell first examined this region in , professor hitchcock had already seen two thousand impressions of feet! it is not difficult to imagine the conditions under which such impressions may have been preserved, for at the present day there are to be seen, on some shores, illustrations of similar operations. dr. gould, of boston, u.s., was the first to call the attention of naturalists to a very instructive example of such processes on the shores of the bay of fundy, where the tide is said to rise in some places seventy feet high. here we have a very perfect surface for receiving and retaining impressions. vast are the numbers of wading and sea-birds that course to and fro over the extensive tract of plastic red surface left dry by the far retreat of the tide in the bay of fundy. during the period that elapses between one spring tide and the next, the highest part of the tidal deposit is exposed long enough to receive and retain many impressions; even during the hours of hot sunshine, to which, in the summer months, this so-trodden tract is left exposed, the layer last deposited becomes baked hard and dry, and before the returning tidal wave has power to break up the preceding one, the impressions left on that stratum have received a deposit. a cast is thus taken of the mould previously made, and each succeeding tide brings another layer of deposit. we can easily imagine that in succeeding ages the petrifying influences will consolidate the sandy layers into a fossil rock. such a rock would split in such a way, along its natural layers of formation, as to show the old moulds on one surface, and the casts on the other. [illustration: fig. .--limb-bones of _allosaurus_. (after marsh.) . fore leg. . hind leg.] professor marsh has had the good fortune to discover a very peculiar new form of carnivorous dinosaur, to which he has given the name ceratosaurus,[ ] because its skull supported a horn. but the horn is not the only new feature presented by this interesting creature. its vertebræ are of a strange and unexpected type; and in the pelvis all the bones are fused together, as in modern birds. externally, also, the ceratosaurus differed from other members of the carnivorous group, for its body was partly protected by long plates in the skin, such as crocodiles have: these extended from the back of the head, along the neck, and over the back. an almost complete skeleton was found which indicates an animal about seventeen feet long. when alive it was probably about half the bulk of the allosaurus mentioned above. (see fig. .) [ ] greek--_keras_, horn; _sauros_, lizard. some authorities consider it to be identical with megalosaurus. seen from above, its skull resembles in general outline that of a crocodile, the facial portion being elongated and gradually tapering to the muzzle, with the nasal openings separate, and placed near the end of the snout. [illustration: fig. .--skull of _ceratosaurus_. top view. (after marsh.)] the teeth of this horned dinosaur resemble those of the megalosaur. its eyes were protected by protuberances of the skull just above the cavity in which the eye was placed (see figs. and ). the brain was a good deal larger in proportion to the size of the animal than in brontosaurus and its allies; so perhaps we may infer that it was endowed with greater intelligence, as it certainly was more active in its habits. the fore limbs, as in megalosaurus, were small, and some of the fingers ended in powerful claws, which no doubt it used to good purpose. perhaps the most remarkable of all the dinosaurs was a diminutive creature only two feet in length, which was related to those we have just been considering, and whose skeleton has been found almost entire in the now famous lithographic stone of solenhofen in bavaria. of this unique type, the compsognathus, the skeleton of which is in many ways so bird-like, professor huxley remarks, "it is impossible to look at the conformation of this strange reptile and to doubt that it hopped, or walked, in an erect or semi-erect position, after the manner of a bird, to which its long neck, slight head, and small anterior limbs must have given it an extraordinary resemblance." (see fig. .) [illustration: fig. .--skull of _ceratosaurus nasicornis_. (after marsh.)] at the head of this chapter are placed the words of dr. mantell, "fossils have been eloquently and appropriately termed _medals of creation_," and the eloquent passage by which those words are followed may be transcribed here. he goes on to say, "for as an accomplished numismatist, even when the inscription of an ancient and unknown coin is illegible, can from the half-obliterated effigy, and from the style of art, determine with precision the people by whom, and the period when, it was struck: in like manner the geologist can decipher these natural memorials, interpret the hieroglyphics with which they are inscribed, and from apparently the most insignificant relics trace the history of beings of whom no other records are extant, and ascertain the forms and habits of unknown types of organisation whose races are swept from the face of the earth, ere the creation of man, and the creatures which are his contemporaries. well might the illustrious bergman exclaim, "_sunt instar nummorum memoralium quæ de præteritis globi nostri fatis testantur, ubi omnia silent monumenta historica._"" [illustration: fig. .--skeleton of _compsognathus longipes_. (from the solenhofen limestone.)] geology owes a deep debt of gratitude to the late dr. gideon a. mantell, who, during the intervals of a laborious professional life, collected and described the remains of several strange extinct reptiles, and wrote a number of works on geology, such as served in his day to advance the science to which he was so enthusiastically devoted. we propose to give a brief account of a wonderful group of dinosaurs, first introduced to the scientific world through dr. mantell's labours. the first of these monsters is the iguanodon, the earliest known individual of the "bird-footed" division (ornithopoda). the history of the gradual reconstruction of its skeleton is an instructive instance of the results that may be obtained by a careful and patient study of fragmentary remains. through the labours of dr. mantell, in the first half of this century, a considerable knowledge was acquired of the greater part of the skeleton, but certain portions remained a puzzle; these, however, were eventually explained by professor huxley and mr. hulke, and a few years ago a series of complete skeletons were most fortunately obtained in belgium, so that now every part of the huge framework of this monster is known to the palæontologist. its history, as a fossil, is a most interesting one, and furnishes one more example of the marvellous insight into the nature of extinct animals displayed by the illustrious baron cuvier. let us begin with the teeth, since they were the first part of the monster brought to light. it is, perhaps, hardly necessary to remark that, to one thoroughly acquainted with the structures of living animals, a tooth, or a series of teeth, will furnish material from which important conclusions with regard to the structure and habits of an extinct animal may be drawn. so, also, with regard to some other parts, such as limb-bones, but more especially the bones of which the backbone is composed (known as vertebræ). these are very important. the veteran anatomist, professor owen, has said, "if i were restricted to a single specimen on which to deduce the nature of an extinct animal, i should choose a vertebra to work out a reptile, and a tooth in the case of a mammal." seven or eight different "characters," he says, may be deduced from a reptilian vertebra. it is, of course, impossible for any one to reconstruct an entire animal from a single bone or a few teeth, yet such fragments indicate in a general way the nature of a lost creation and its position in the animal kingdom. [illustration: fig. .--tooth of iguanodon, with the apex slightly worn. (from the wealden beds of tilgate forest. natural size.) . front aspect, showing the longitudinal ridges and serrated margins of the crown. . view of the back, or inner surface of the tooth. _a._ serrated margins. _b._ apex of the crown worn by use.] it is all the more important to give to the general reader this warning, because an impression seems still to remain in the popular mind that owen could and did restore extinct types from a single bone or a single tooth; but no anatomist would attribute to any mortal man such superhuman power. let us, therefore, while gratefully acknowledging the debt we all owe to the great naturalist--who has gone to his rest since our first edition appeared--not attribute to him impossible things. nor can it be denied that even he sometimes fell into error, or drew conclusions not borne out by later discoveries. it must also be confessed that in some respects he lagged behind in the march of scientific progress. while on this subject we cannot do better than quote some remarks of our friend, mr. a. smith woodward, of the natural history museum, in an able review of sir richard's work on vertebrates.[ ] he says, "owen, in fact, was cuvier's direct successor, and, apart from his striking hypotheses ..., it is in this character that he has left the deepest impression upon biological science. extending and elaborating comparative anatomy as understood by cuvier, owen concentrated his efforts on utilising the results for the interpretation of the fossil remains--even isolated bones and teeth--of extinct animals. he never hesitated to deal with the most fragmentary evidence, having complete faith in the principles established by cuvier; and it is particularly interesting, in the light of present knowledge, to study the long series of successes and failures that characterise his work. however, unwittingly, owen may be said to have contributed most to the demolition of the narrow cuvierian views. when dealing with animals closely related to those now living, his correctness of interpretation was usually assured; when treating of more remote types, he could do little more than guess, unless tolerably complete skeletons happened to be at his disposal.... "in short, owen's work on fragmentary fossils has demonstrated that the principles of comparative anatomy are very different from those inferred by cuvier from his limited field of observation, and the discoveries of leidy, marsh, cope, scott, and osborn, in america, have finally led to a new era that owen only began to foresee clearly in his later days." [ ] _natural science_, ii. p. . (feb. .) the first specimens of teeth of the iguanodon were found by mrs. mantell, in , in the coarse conglomerate of certain strata in tilgate forest, belonging to the cretaceous period (see table of strata, appendix i.). dr. and mrs. mantell subsequently collected a most interesting series of these remarkable teeth (which, for a time, puzzled the most learned men of the day), from the perfect tooth of a young animal, to the last stage, that of a mere long stump worn away by mastication. in external form they bore a striking resemblance to the grinders of herbivorous mammals, and were wholly unlike any that had previously been known. even the quarrymen, accustomed to collect the remains of fishes, shells, and other objects embedded in the rocks, had not observed fossils of this kind; and until dr. mantell showed them his specimens, were not aware of the presence of such teeth in the stone they were constantly breaking up for the roads. the first specimen that arrested his attention was a large tooth, which, from the worn surface of its crown, had evidently once belonged to some herbivorous animal. in form it so entirely resembled the corresponding part of an incisor tooth of a large pachydermatous animal ground down by use, that dr. mantell was much embarrassed to account for its presence in the ancient wealden strata, in which, according to all previous experience, no fossil remains of mammals would be likely to occur. no reptiles of the present day are capable of masticating their food; how, then, could he venture to assign it to a reptile? here was a puzzle to be solved, and in his perplexity he determined to try whether the great naturalist at paris would be able to throw any light on the question. through sir charles (then mr.) lyell, this perplexing tooth was submitted to baron cuvier; and great was the doctor's astonishment on hearing that it had been without hesitation pronounced to be the upper incisor of a rhinoceros! the same tooth, with some other specimens, had already been exhibited at a meeting of the geological society, and shown to dr. buckland, mr. conybeare, and others, but with no more satisfactory result. worse than that: dr. mantell was told that the teeth were of no particular interest, and that, without doubt, they either belonged to some large fish, or were the teeth of a mammal, and derived from some superficial deposit of the "glacial drift," then called diluvium. there was one man, however, who foresaw the importance of mantell's discovery, and that was dr. wollaston. this distinguished philosopher, though not a naturalist, supported the doctor's idea that the teeth belonged to an unknown herbivorous reptile, and encouraged him to continue his researches. as if to add to the difficulty of solving the enigma, certain bones of the fore limb, discovered soon after in the same quarry and forwarded to paris, were declared to belong to a species of hippopotamus! another very curious bone--of which we shall speak presently--was declared to be the lesser horn of a rhinoceros! the famous dr. buckland even went so far as to warn dr. mantell not to publish it forth that these bones and teeth had been found in the tilgate forest strata. to him it seemed incredible that such remains could have been obtained from beds older than the superficial drift deposits of the district. we must bear in mind that in those days palæontology, or the knowledge of the world's former inhabitants, was a new science still in its infancy, and the idea of mammals having existed so far back as the cretaceous period must have appeared incredible. however, the workmen in the quarry were stimulated by suitable rewards, and at length the doctor's efforts resulted in the discovery of teeth which displayed the curious serrated edges, and the entire form of the unused crown. having forwarded specimens and drawings of these to paris, dr. mantell went to london, and ransacked all the drawers in the hunterian museum that contained jaws and teeth of reptiles, but without finding any that threw light on this subject. fortunately, mr. samuel stuchbury, then a young man, was present, and proposed to show him the skeleton of an iguana, which he had himself prepared from a specimen that had long been immersed in spirits. and now the puzzle was in a fair way to being solved; for, to his great delight, the doctor found that the minute teeth of that reptile bore a closer resemblance in their general form to those from tilgate forest than any others he had ever seen. in spite of this fortunate discovery, however, others remained obstinate and unconvinced; and it was not until he had collected a series of specimens, exhibiting various stages of the teeth, that the correctness of his opinion was admitted, either as to their true interpretation, or the age of the strata in which they were imbedded. and now there came good news from paris. cuvier, with the fresh material submitted to him, had boldly renounced his previous opinion, and gave the weight of his great authority to the view maintained by the discoverer of these teeth. in a letter to the doctor he said that such teeth were quite unknown to him, and that they belonged to some reptile. he suggested that they implied the existence of a _new animal_, a _herbivorous reptile_. time would either confirm or disprove the idea, and in the mean time he advised dr. mantell to seek diligently for further evidence, and, if part of a jaw could be found with teeth adhering, he believed he could solve the problem. in his immortal work, _ossemens fossiles_, cuvier generously admits his former mistake, and said he was entirely convinced of his error. baron cuvier alone amongst the doctor's friends or correspondents was able to give any hint as to the character and probable relations of the animal to which the recently discovered teeth belonged. being hampered by arduous professional duties in a provincial town, remote from museums and libraries, dr. mantell transmitted to the royal society figures and drawings of the specimens, and, at the suggestion of the rev. w. d. conybeare, adopted the name iguanodon (iguana-tooth) for the extinct reptile, a name which pointed to the resemblance of its teeth to those of the modern iguana, a land-lizard inhabiting many parts of america and the west indies, and rarely met with north or south of the tropics. these lizards are from three to five feet in length, and perfectly harmless, feeding on insects and vegetables, and climbing trees in quest of the tender leaves and buds, which they chip off and swallow whole; they nestle in the hollows of rocks, and deposit their eggs in the sands and banks of rivers. in all living reptiles the insects or vegetables on which they feed are seized by the tongue or teeth, and swallowed whole, so that a movable covering to the jaws, similar to the lips and cheeks of the mammalia, is not necessary, either for seizing and retaining food, or for subjecting it by muscular movements to the action of the teeth. it is the power of perfect mastication possessed by the iguanodon that is so strange, for it implies a most remarkable approach in extinct reptiles to characters possessed now only by herbivorous mammalia, such as horses, cows, deer, etc. from this and other strange characters seen in the dinosaurs, we learn that they in their day played the part of our modern quadrupeds, whether carnivorous or herbivorous, and showed a remarkable approach to the mammalian type, which of course is a much higher one. it is, therefore, not to be wondered at that dr. mantell's contemporaries, with the exception of cuvier, found in the teeth we have described an awkward puzzle, and refused to believe that they belonged to a reptile. such a notion was at variance with all previous experience, and we naturally form our conclusions to a large extent by experience. let us, then, beware lest we allow our ideas to be limited by what after all is, as it were, only an expression of our ignorance. the hottentot who has never seen snow would refuse to believe that rain can assume a solid form; and, in the same way, if we bind ourselves down by experience, we might refuse to believe in some of the still more wonderful dinosaurian types to be described in this chapter, such as the triceratops, with a pair of large horns, a skull over six feet long, and limbs larger than those of the rhinoceros! (see p. ). the strange vagaries of dinosaurs have led professor marsh and other authorities to exalt them, from their former position of a mere order in the reptile class, to the dignity of a sub-class all to themselves; and there is much to be said for this view. compared with the marsupials, living and extinct, they show an equal diversity of structure and variations in size from by far the largest land animals known down to some of the smallest.[ ] [ ] bauer, after a full critical examination of the dinosauria, considers that one order is insufficient, and has proposed to make three orders of them, which he names after the iguanodon, cetiosaurus, and megalosaurus. the importance of discovering, if possible, a portion of the jaw of an iguanodon was fully recognised by dr. mantell, and, urged on by the encouragement he had received from the illustrious cuvier, he eagerly sought for the required evidence. but nearly a quarter of a century elapsed before it was forthcoming. in and , however, portions of the lower jaw, with some teeth attached, were found; and his memoir _on the structure of the jaws and teeth of the iguanodon_ was published by the royal society in . for this important communication the gold medal of the society was awarded to the author. the second of these finds (by captain brickenden) confirmed in every essential particular the inferences suggested by the detached teeth. the first important connected series of bones of this monster was discovered in , by mr. bensted, in the "kentish rag" quarries of the lower greensand formation at maidstone. mr. bensted, who was the proprietor of the quarry, one day had his attention drawn by the workmen to what they supposed to be petrified wood in some pieces of stone which they had been blasting. he perceived that what they supposed to be wood was fossil bone, and, with a zeal and care which have always characterised this estimable man (says professor owen) in his endeavour to secure for science any evidence of fossil remains in his quarry, he immediately resorted to the spot. he found that the bore, or blast, by which these remains were brought to light had been inserted into the centre of the specimen, so that the mass of stone containing it had been shattered into many pieces, some of which were blown into the adjoining fields! all these pieces he had carefully collected, and, proceeding with equal ardour and success to the removal of the matrix from the fossils, he succeeded, after a month's labour, in exposing them to view, and in fitting the fragments in their proper place. this valuable specimen was presented to dr. mantell (and afterwards purchased with the rest of his collection by the british museum), and its present condition is the result of his skill, as well as that of its discoverer. certain gentlemen in brighton, anxious that the specimen should be placed in the hands of the original discoverer of iguanodon, purchased and presented it to dr. mantell--a tribute of respect which was highly gratifying to him. (wall-case .) it belonged to a young iguanodon. this fortunate discovery was one of those cuvier foresaw, and has served to verify his sagacious conjecture that some of the great bones collected by the doctor from the wealden strata of sussex belonged to the same animal, and to confirm other conclusions formed by the discoverer of the iguanodon. great was dr. mantell's delight on finding that every bone he had ascribed to iguanodon solely from analogy was present in the maidstone specimen. one of the chief advantages of this discovery was that it afforded demonstration of the characters of the vertebræ, which, as previously stated, are very important to the anatomist. of these professor owen has given full descriptions, and has shown that they differ from those of any animal previously known, whether living or extinct. it is very interesting, in the light of recent discoveries, to read the conclusions arrived at by mantell and owen, with regard to the organisation of this great wealden reptile, and to see how, with the exception of certain details, they have been confirmed. considering the imperfect nature of the materials at their command, it is wonderful that their forecasts should have turned out so successful. thus professor owen predicted for the iguanodon a total length of twenty-eight feet, and specimens discovered of late years show a length of twenty-four feet. in some, the thigh-bone exceeded a yard in length; this indicated an animal of great size, since in the largest crocodiles this bone is scarcely a foot long. again, dr. mantell, from a study of the imperfect jaw-bones in his collection, concluded that the lower jaw was invested with a well-developed fleshy flexible lip, and that the mouth was provided with a tongue of great mobility and power. "there are strong reasons," he says, "for supposing that the lip was flexible, and, in conjunction with the long fleshy prehensile tongue, constituted the instrument for seizing and cropping the leaves and branches, which, from the construction of the molars, we may infer, constituted the chief food of the iguanodon. the mechanism of the maxillary organs (jaws), as elucidated by recent discoveries, is thus in perfect harmony with the remarkable characters which rendered the first known teeth so enigmatical; and in the wealden herbivorous reptile we have a solution of the problem, how the integrity of the type of organisation peculiar to the class of cold-blooded vertebrata was maintained, and yet adapted, by simple modifications, to fulfil the conditions required by the economy of a gigantic terrestrial reptile, destined to obtain support exclusively from vegetable substances; in like manner, as the extinct colossal herbivorous edentata (sloths, see chapter xii.), which flourished in south america ages after the country of the iguanodon and its inhabitants had been swept away from the face of the earth." dr. mantell also was the first to prove, from the nature of the wealden strata, that they were deposited in or near the estuary of a mighty river. with regard to the aspect of the country in which the iguanodon flourished, he showed that coniferous trees probably clothed its alpine regions; palms and arborescent ferns, and cycadaceous plants (_i.e._ plants resembling the modern zamia, or "false palm"), constituted the groves and forests of its plains and valleys; and in its fens and marshes the equisetaceæ (mare's-tails) and plants of a like nature prevailed. [illustration: plate vii. a gigantic dinosaur, iguanodon bernissartensis. length about feet.] the iguanodons of the wealden epoch did not live and die where their bones are now found--the condition in which their fossil relics occur proves that they floated down the streams and rivers, with rafts of trees and other spoils of the land, till, arrested in their course, they sank down and became buried in the fluviatile and sometimes marine sediments then being slowly laid down. in this way only can we account for the generally broken and rolled condition of the bones, their separation from each other, the numerous specimens of teeth which must have been detached from their sockets, and the broken stems and branches of trees without leaves that have been found in the wealden strata of england. since the days of dr. mantell, the remains of iguanodon, or closely allied genera, have been found on the continent, in other parts of england, and in north america, in strata of various ages, from the trias or new red sandstone to the chalk (see table of strata, appendix i.). the american hadrosaurus must have decidedly resembled the iguanodon. the beautiful restoration by our artist (plate vii.) is based upon the belgian specimens described in the following chapter. chapter vii. dinosaurs (_continued_). "everything in nature is engaged in writing its own history: the planet and the pebble are attended by their shadows, the rolling rock leaves its furrows on the mountain side, the river its channel in the soil, the animal its bones in the stratum, the fern and the leaf inscribe their modest epitaphs on the coal, the falling drop sculptures its story on the sand and on the stone,--not a footstep on the snow or on the ground, but traces in characters more or less enduring the record of its progress."--emerson. in the year was announced one of the most fortunate discoveries known in the whole history of geological science--a discovery unique of its kind, and one which throws considerable light on the nature of the monster first discovered by dr. mantell. in that year came the good news that no less than twenty-three iguanodons had been found in the colliery of bernissart, in belgium, between mons and tournai, near the french frontier. the coal-bearing rocks (coal-measures) of this colliery, overlain by chalk and other deposits of later age, are fissured in many places by deep valleys or chasms more than yards deep. though now filled up, they must at one time have been open gorges on an old land surface. into one of these chasms were somehow precipitated twenty-three iguanodons, numbers of fish, a frog-like animal, several species of turtles, crocodiles, and numerous ferns similar to those described by mantell from the weald. it it not easy to conjecture how this large and varied assemblage of animals came to be collected together and entombed in this one place, but possibly their carcases were swept by some flood into the chasm in which the remains were discovered. they were buried in clay interstratified with sand, a fact which was interpreted in accordance with the above suggestion. m. de pauw, the accomplished controller of the workshops in the royal museum of natural history at brussels, spent three whole years in extracting this splendid series of fossils from the pit-shaft, the bones being brought up from a depth of rather more than yards. but at the end of this time it was only the rough material that had been got together, and every block containing bones requires a great deal of most careful labour before the bones in it are so exposed that they can be properly studied. out of the twenty-three specimens, fifteen had, in the year , been chiselled out, eight remaining to be worked at; and although five skilled workmen were then constantly at work, progress was necessarily slow. in , that is after seven years, two huge entire skeletons had been set up in a great glass case in the courtyard of the museum at brussels, and these exhibit with marvellous completeness the structure of the extinct monster.[ ] the work reflects the highest credit on m. de pauw;[ ] and the director of the bernissart mining company, m. fages, deserves the thanks of all scientific men for so liberally aiding this important undertaking. these specimens illustrate the conclusion, previously arrived at by professor huxley, that dinosaurs, as a group, occupy a position in the great chain of animal life intermediate between reptiles and birds. indeed, it is the opinion of this great authority, and of many naturalists of the present day, that whenever future discoveries may reveal the ancestry of birds, it will be found that they came from dinosaurs, or that both originated from a common ancestor. [ ] in august, , mr. dollo wrote, in answer to inquiries from south kensington, to say that five are already mounted and exhibited, and five more are almost ready for mounting. he also stated that the remains represent twenty-nine individuals, not twenty-three, as above. [ ] _geological magazine_, january, . the specimens so skilfully set up by m. de pauw represent two distinct species. the larger one, iguanodon bernissartensis, cannot be less than fifteen feet high, and, measured from the tip of the snout to the end of the tail, is rather over thirty feet long, covering nearly twenty-four feet of ground in its erect position (see fig. ). iguanodon mantelli is smaller and more slender looking, with a height of over ten feet, and a length of about twenty feet. (see fig. .) [illustration: fig. .--skeleton of _iguanodon bernissartensis_.] [illustration: plate viii. iguanodon mantelli. length about feet.] [illustration: fig. .--skull and skeleton of _iguanodon mantelli_. (from bernissart.)] the huge three-toed impressions found in sussex prove that the monster, although owning a body as large as that of an elephant, habitually walked on its hind legs! some of the thighbones found by dr. mantell measured between four and five feet in length. it will be seen that the fore limbs are small in comparison to the hind limbs. a remarkable feature of the hand is the large pointed bone at the end of the thumb, forming a kind of spur. the conical shape of this bone found by dr. mantell, who had no clue to its place in the skeleton, led him to suppose that it was a horn answering to that of a rhinoceros--a conclusion which professor owen refused for various reasons to accept. the latter concluded that it belonged to the hand, and now we see that he was right. unfortunately, certain popular works on geology, such as _our earth and its story_ (cassell) still continue to spread this error, by showing a (very indifferent) restoration of the iguanodon with the impossible horn on its nose. it has been suggested that the spur was a weapon of offence, and that, when attacked, an iguanodon may have seized its aggressor in its short arms, and made use of the spur as a dagger. but this is only conjecture, and perhaps the spur may have been useful in seizing and pulling down the foliage and branches of trees, or in grubbing them up by the roots. detached specimens of this curious bone may be seen among the other remains of iguanodon at south kensington, and also some of the gigantic tracks already alluded to. (gallery iv. on plan, wall-cases and ; and gallery xi., wall-case .) the bernissart specimens even afford some evidence as to the nature of the integument, or skin, and this supports the idea previously held that the creature possessed a smooth skin, or, at least, only slightly roughened. the muzzle was quite toothless, and perhaps may have been sheathed in horn, like the beak of turtles--an arrangement highly useful for biting off the leaves of trees. [illustration: fig. .--tracks of _iguanodon_, much reduced. (from wealden strata, sussex.)] probably it passed much of its time in the water, using its immense powerful tail as an organ of propulsion. when swimming slowly it may have used both sets of limbs, but when going fast it probably fixed its fore limbs closely beside its body, and drove itself through the water by means of the long hind limbs alone. mr. dollo, of brussels, is preparing a final monograph on the bernissart iguanodons, a work to which palæontologists eagerly look forward. there cannot be much doubt that these unarmoured dinosaurs were molested and preyed upon by their carnivorous contemporaries, such as the fierce megalosaurus, previously described (p. ). and with regard to this, mr. dollo makes the suggestion that, when on land, their great height and erect posture enabled them to descry such enemies a long way off. their great height must also have stood them in good stead, by enabling them easily to reach the leaves of trees, tree-ferns, cycads, and other forms of vegetable life, which constituted their daily food. (see restorations, plates vii. and viii.) should the reader visit the "geological island" in the grounds of the crystal palace, he will see that mr. waterhouse hawkins's great model iguanodon there set up is by no means in accordance with the description given above; but we must remember how imperfect was the material at his command. another dinosaur, of considerable dimensions, that flourished during the wealden period was the hylæosaurus, also discovered by dr. mantell, and so named by him because it came from the weald.[ ] in the summer of , upon visiting a quarry in tilgate forest, which had yielded many organic remains, he perceived in some fragments of a large mass of stone which had recently been broken up and thrown in the roadside, traces of numerous pieces of bone. with great care he cemented together and fixed in a stout frame, all the portions of this block that he could find, and set to work to "develop" the block with his chisel. this work occupied many weeks, but his labour was rewarded by the discovery of certain new and remarkable features displayed by this monster; for it must have presented, when alive, a formidable array of bony plates and long sharp spines, the latter of which probably stood in bristling array along the back and tail, and other parts of the body. (wall-case .) of the spines no less than ten were found in this block, varying in length from five to seventeen inches, the largest being four inches thick. it is known that many lizards, such as iguanas and cycluras, have large processes with horny coverings, forming a kind of fringe or crest along the back, and, judging by analogy, dr. mantell concluded that this gigantic saurian was similarly armed with a row of large angular spines covered by a thick horny investment. as weapons of offence and defence, they were no doubt highly effective, but their precise arrangement is still a matter of speculation. [ ] from greek--_hule_, wood, or weald; and _sauros_, lizard. this first specimen displayed, besides the bony scutes and spines, a portion of the backbone, eleven ribs and portions of the pectoral arch. a second specimen was found near bolney, in sussex, and was unfortunately almost wholly destroyed by the labourers; but dr. mantell was able to obtain many of the bones, such as ribs and limb-bones, and they also indicated a reptile of great size. a third specimen was brought to light in tilgate forest in ; but, unfortunately, this also fell into the hands of the parish labourers, who were unacquainted with its value. although with due care a much larger portion of the skeleton might have been kept, yet dr. mantell was able to obtain a fine series of twenty-six vertebræ belonging to the tail, with a total length of nearly six feet: the same spines were present here also. no specimen of the skull of this strange monster is known, and no teeth that can be with certainty referred to it. mr. waterhouse hawkins's model at sydenham, near the iguanodon, was based on the above discoveries, which are insufficient, and is far from the truth. [illustration: plate ix. an armoured dinosaur, scelidosaurus harrisoni. length feet or more.] [illustration: fig. .--restored skeleton of _scelidosaurus harrisoni_ (after woodward), greatly reduced, from the lower lias of charmouth, dorset. the figure shows the large lateral dermal spines on the shoulders, and the long lateral line of smaller spines, reaching from the pectoral region to the extremity of the tail.] * * * * * the next monster to be described is one that has fortunately left to posterity a much better record of itself, and probably was not very unlike the hylæosaurus of mantell. this is the scelidosaurus: so named by professor owen from the indications of greater power in the hind legs than in most saurians.[ ] it is the only known example of an almost entire skeleton of an english dinosaur, and the history of its discovery is rather curious. some time previous to , mr. j. harrison, of charmouth, obtained from the lower lias of that neighbourhood portions of the hind limb of a dinosaur, and, later on, a nearly complete skull. these specimens were described by owen, and the genus was founded on them. mr. harrison, whose discovery aroused great interest, continued to search on the same spot, and was rewarded by finding all the rest of the skeleton, except most of the neck vertebræ. this was extracted in several blocks, and these, after careful "development" of the bones, were fitted together so as to exhibit the whole skeleton. this most valuable specimen can now be seen at south kensington in a separate glass case, and is one of the treasures of the unrivalled gallery of fossil reptiles. the case is placed so that both sides of the specimen can be seen (case y, gallery iv., on plan). its length is about twelve feet; perhaps the individual it represents was not fully grown, but, on account of the absence of most of the neck vertebræ, it is impossible to give the exact length. both hind limbs are entire and well seen, but of the fore limbs the hands are wanting. the former were provided with four "functional" toes--that is, toes that were used,--and one "rudimentary" or unused one. there were two big spines, one placed on each shoulder, and a series of long plates arranged in lines along the back and side. plate ix. shows an attempted restoration of this remarkable dinosaur based upon the skeleton just described. it seems to have been organised for a terrestrial rather than an aquatic life, but to have been amphibious, frequenting the margins of rivers or lakes. professor owen considers that the carcase of this individual drifted down a river emptying itself in the old liassic sea, on the muddy bottom of which it would settle down when the skin had been so far decomposed as to permit the escape of gases due to decomposition. in that case the carcase would attract large carnivorous fishes and reptiles, such as swarmed in this old sea, so that portions of the skin and flesh would probably be torn away before the weight of the bones had completely buried it in mud. in this way, perhaps, the loss of much of the external armature and of the two fore feet may be accounted for. the hind limbs, being stronger, were better able to resist such attacks, and they are therefore preserved. like many other specimens, this fossil has, in the course of ages, been subjected to enormous pressure from overlying strata, causing compression and dislocation or fracture. [ ] from greek--_scelis_, limb, and _sauros_, lizard. but there were in existence during the long jurassic period, other and even stranger forms of armoured dinosaurs. one of these, only imperfectly known at present, was the many-spined polacanthus.[ ] this remarkable monster had the whole region of the loins and haunches protected by a continuous sheet of bony plate armour, rising into knobs and spines, after the fashion of the shield or carapace of certain extinct armadillos known as glyptodonts (see chapter xii.). a specimen of such a shield is to be seen in the collection at south kensington (wall-case ). it is to be hoped that, some day, further remains of the polacanthus will be brought to light, so that a restoration may become possible. dr. mantell had already pointed out certain analogies between iguanodon and the huge extinct sloths of the south american continent, that flourished in the much more recent pleistocene period; and this idea is now considerably strengthened by the later discoveries of armoured dinosaurs. these are his words: "in fine, we have in the iguanodon the type of the terrestrial herbivora which, in the remote epoch of the earth's physical history termed by geologists _the age of reptiles_, occupied the same relative position in the scale of being, and fulfilled the same general purposes in the economy of nature, as the mastodons, mammoths, and mylodons (extinct sloths) of the tertiary period, and the existing pachyderms." [ ] from greek--_polus_, many, and _acantha_, spine. it is, perhaps, one of the most interesting discoveries of modern geology, that certain races of animals now extinct have in various ways assumed some of the characteristics presented by animals much higher in the scale of being, that flourish in the present day. it seems as if there had been some strange law of anticipation at work, if we may venture so to formulate the idea. it has already been shown how the great saurians ichthyosaurus and plesiosaurus presumed to put on some of the characters of whales, and to play their _rôle_ in nature, though they were only reptiles; how the carnivorous dinosaurs acquired teeth like those now possessed by lions and tigers, which also are mammals; and now we find herbivorous dinosaurs imitating the glyptodon, an armadillo that lived in south america almost down to the human period. we shall not lose sight of this very interesting and curious discovery, for other cases will present themselves to our view in future chapters. the reader might ask, "if reptiles were able in these and other ways to imitate the mammals of to-day, or of yesterday, why should they not have been able to go a few steps further, and actually _become_ mammals?" the evolutionist, if confronted with such a question, would say, that there is no evidence of dinosaurs turning into mammals, but that both may have branched off at an early geological period (say the permian) from a primitive group of reptiles, or even of amphibians. it must be borne in mind that, during the "age of reptiles" (mesozoic period), the mammalian type was but feebly represented by certain small and humble forms, probably marsupials. as far as we know, there were no big quadrupeds such as flourish to-day; therefore reptiles played their part, and in so doing acquired some of their habits and structural peculiarities. it is difficult for us, living in an age of quadrupeds, to realise this, and to picture to ourselves reptilian types posing as "lords of creation," or, to use a homely phrase, "strutting in peacock's feathers." * * * * * leaving now the english herbivorous dinosaurs, we pass on to those still more wonderful forms discovered of late years by professor marsh. the former have been treated at considerable length, first because they are english, and, as such, the history of their discovery possesses considerable interest; secondly, because their elucidation reflects the highest credit on our great pioneers in this fruitful field of research, and illustrates the manner in which great naturalists have been able to draw most important and wonderful conclusions (afterwards verified in most cases) from material apparently far from promising. for example, cuvier's prophecy of the iguanodon from a few teeth is a striking example of the result of reasoning from the known to the unknown, an example which seems to us worthy to be ranked with the discovery of neptune by adams and leverrier, or, to take a more recent case, the discovery by mendeleef of the periodic law, by means of which he has foretold the discovery of new chemical elements. whatever may have been the origin of the great mammalian class, the possibility and even probability of birds and dinosaurs being descended from a common ancestor is a theory for which much may be said, and it has been adopted by many leading naturalists of the present day, who have been convinced by professor huxley's clear elucidation of the nature of the pelvic region in the group of dinosaurs which has been above described (the ornithopoda, or bird-footed group). it was professor huxley who first propounded this interesting speculation, basing his belief on the many bird-like characters presented by this strange group of extinct reptiles--the small head and fore limbs, the long and often three-toed hollow hind limbs, the bones of the pelvis or haunch, their habit of walking in a semi-erect position on those limbs (as proved by their tracks), and in some of hopping, as the little compsognathus most probably did. and, last but not least, the strange mixture of bird-like and reptilian characters presented by certain most anomalous birds discovered by professor marsh in american cretaceous rocks, viz. the huge hesperornis and the smaller ichthyornis. speaking on this subject some years ago, professor marsh said, "it is now generally admitted by biologists who have made a study of vertebrates, that birds have come down to us through the dinosaurs, and the close affinity of the latter with recent struthious birds (ostrich, etc.), will hardly be questioned. the case amounts almost to a demonstration, if we compare with dinosaurs their contemporaries, the mesozoic birds. the classes of birds and reptiles, as now living, are separated by a gulf so profound that a few years since it was cited by the opponents of evolution as the most important break in the animal series, and one which that doctrine could not bridge over. since then, as professor huxley has clearly shown, this gap has been virtually filled by the discovery of bird-like reptiles and reptilian birds. compsognathus and archæopteryx of the old world, and ichthyornis and hesperornis of the new, are the stepping-stones by which the evolutionist of to-day leads the doubting brother across the shallow remnant of the gulf, once thought impassable."[ ] [ ] _the introduction and succession of vertebrate life in america._ an address delivered before the american association for the advancement of science, at nashville, tenn., august, . see _nature_, vol. xvi. we now pass on to describe two of the strangest and most wonderful of all the dinosaurs, recently discovered in the far west. the first of these is the stegosaurus,[ ] or plated lizard, not wholly unknown before, because part of its skeleton was found some years ago in a brickfield in the kimmeridge clay at swindon. it has been proved that some of the bones to which the name omosaurus[ ] has been applied really belonged to the former genus. [ ] greek--_stegos_, roof or covering; _sauros_, lizard. [ ] greek--_omos_, humerus, and _sauros_, lizard. with such complete specimens now known by professor marsh's descriptions, it will not be necessary to mention the meagre remains discovered in this country, or the conclusions arrived at by owen and seeley, interesting as they are. in the year professor marsh described, in the _american journal of science_, a considerable portion of a skeleton of a stegosaur, remarking that this genus proved to be one of the most remarkable animals yet discovered. it was found on the eastern flank of the rocky mountains, in strata of jurassic age; they indicated an animal about twenty-five feet long, and for this discovery science is indebted to professor a. lakes and engineer h. c. beckwith of the united states navy, who found the remains in colorado, near the locality of the gigantic atlantosaurus. the solid limb-bones seem to point to an aquatic life, but there can be little doubt that the monster did not pass all its time in the water. (fig. shows the skeleton.)[ ] [ ] the writer is informed that this skeleton is not yet mounted in the yale college museum, but that it will be before long. our artist has drawn it as if set up, with a man standing by for comparison. in professor marsh announced the discovery of additional remains from several localities. the most striking feature--from which the stegosaur takes its name--was the presence of huge bony plates belonging to its skin, as well as large and small spines. some of the plates were from two to three feet in diameter, and they were of various shapes. of the spines, some were of great size and power, one pair being each over two feet long! the skull was remarkably small, and more like that of a lizard than we find in most dinosaurs; the jaws were short and massive. little was known at first of the brain, but fortunately a later discovery showed the brain-case well preserved. later still, more than twenty other specimens of this dinosaur were obtained, so that nearly every portion of the skeleton is now known. the skulls indicate that the creature possessed large eyes and a considerable power of smell. the jaws contain but a single row of teeth in actual use; but as these wore out, they were replaced by others lodged in a cavity below. teeth, however, were not its strong point; they indicate a diet of soft succulent vegetation. the vertebræ have the faces of their centra more or less bi-concave. many curious features in the skeleton can only be explained with reference to the heavy armour of plates and spines with which the stegosaur was provided. thus the vertebræ have their "neural spines" expanded at the summit to aid in supporting part of the armour. (see fig. .) the fore limbs were short and massive, but provided with five fingers; the hind limbs were very much larger and more powerful. these and the powerful tail show that the monster could support itself on them as on a tripod, in an upright position, and this position must have been easily assumed in consequence of the massive hind quarters. as in iguanodon, there were three toes to the hind feet, and these were probably covered by strong hoofs. the fore limbs could move freely in various directions like a human arm, and were probably used in self-defence. (see fig. .) but for this purpose the tail with its four pairs of huge spines would be very effective, and one could easily imagine that a single deadly blow from such a tail would be sufficient to drive away, if not to kill, one of the carnivorous enemies of the species. all the plates and spines were, during life, protected by a thick horny covering, which must have increased their size and weight. such a covering seems to be clearly indicated by certain grooves and impressions that mark their surfaces. (see fig. .) the largest plates are unsymmetrical, and were probably arranged along the back, as in our restoration, plate ix. it will be noticed, by those who are familiar with our first edition that plate x. gives a somewhat different representation of the stegosaur, in which the length of the hind limbs is more apparent, and also they are more free from the body. [illustration: fig. --skeleton of _stegosaurus ungulatus_; length about feet. (after marsh.)] [illustration: plate x. a gigantic armoured dinosaur, stegosaurus ungulatus. length about feet.] [illustration: fig. .--tail vertebræ of _stegosaurus_. (after marsh.) . side view. . front view.] finally, the stegosaur displays a rather remarkable feature; for a very large chamber was found in the sacrum[ ] formed by an enlargement of the spinal cord. the chamber strongly resembled the brain-case in the skull, but was about ten times as large! so this anomalous monster had two sets of brains, one in its skull, and the other in the region of its haunches! and the latter, in directing the movements of the huge hind limbs and tail, did a large share of the work. the subject is a highly suggestive one, but at present requires further explanation. [ ] the sacrum may be thus defined: the vertebræ (usually fused together) which unite with the haunch-bones (_ilia_) to form the pelvis. [illustration: fig. .--limb-bones of _stegosaurus_. (after marsh.) . fore leg. . hind leg.] on the walls of the fossil reptile gallery at south kensington the reader will find a large framed drawing of the skeleton of stegosaurus, kindly sent by professor marsh, whose forthcoming monograph will be welcomed by all palæontologists. [illustration: fig. .-- , . plates of stegosaurus. the middle figures show their thickness. (after marsh.)] [illustration: fig. .-head of _triceratops_, seen from above. (after marsh.)] the last, and in some ways the strangest of the dinosaurs, was the triceratops[ ] that flourished in america at the end of the long mesozoic era, during the cretaceous period. the name refers to the three horn-cores found on the skull, which probably supported true horns like those of oxen. whereas the stegosaur was provided with quite a small skull, this monster had one of huge dimensions and remarkable shape (see figs. and ).[ ] in the younger ones it was about six feet long, but in an old individual must have reached a length of seven or eight feet. such a skull is only surpassed by some whales of the present day. twenty different skulls of this kind have been found, and professor marsh places the horned dinosaurs in a separate family, to which he has given the name ceratopsidæ, or horn-faced. their remains come from the laramie beds, believed to be of cretaceous age, but representing a remarkably mixed fauna and flora, so that some have considered them to be tertiary. the strata containing these fossils are very rich in organic remains, and have yielded not only other dinosaurs, but plesiosaurs, crocodiles, turtles, many small reptiles, a few birds, fishes, and small mammals. the ceratops beds are of fresh-water or brackish origin, and can now be traced for nearly eight hundred miles along the east flank of the rocky mountains. [ ] greek--_treis_, three; _ceras_, horn; _ops_, face. [ ] this skeleton has not yet been set up in the yale college museum, but will be before long. our artist has drawn it as if set up, with a man standing by for comparison. in an article in _the californian illustrated magazine_ for april, (quoted in the _review of reviews_ for may), an american writer incorrectly describes this monster as "higher than jumbo, and longer than two jumbos placed in a row." but the article is altogether untrustworthy, and the two "restorations" are absurd. [illustration: fig. .--skeleton of _triceratops prorsus_; length about feet. (after marsh.)] in this dinosaur we find the fore feet larger than usual in proportion to the hind limbs, and there can be no doubt that it walked on all fours. its length was about twenty-five feet. all the vertebræ and limb-bones are solid. the brain was smaller in proportion to the skull than in any known vertebrate. the teeth are remarkable in having two distinct roots. the wedge-like form of the skull is also very peculiar. the two large horns come immediately over the eyes, and the small one above the nose; this dinosaur was, therefore, well provided with weapons of offence, such as would be highly useful in driving away or wounding carnivorous enemies. the back part of the skull rises up into a kind of huge crest, and this during life was protected by a special fringe of bony plates. such an arrangement doubtless formed an effective shield to ward off blows when one triceratops was fighting another, as bulls or buffaloes of the present day fight with their horns. the mouths of these dinosaurs formed a kind of beak, sheathed in horn. the body as well as the skull was protected, but the nature and position of the defensive parts in different forms cannot yet be determined with certainty. various spines, bones, and plates have been found that evidently were meant for the protection of the creature's body, and belonged to the skin. probably some of these were placed on the back, behind the crest of the skull; some may have defended the throat, as in stegosaurus. altogether, triceratops is very different to any other dinosaur. one cannot help picturing it rather as a fierce rhinoceros-like animal. in the restoration (plate xi., frontispiece) our artist has given it a thick skin, rather like that of the rhinoceros, only indicating small bony plates, etc., here and there. professor marsh thinks that as the head increased in size to bear its armour of bony plates, the neck first, then the fore feet, and then the whole skeleton was specially modified to support it; and he concludes that as these changes took place in the course of the evolution of this wonderful dinosaur, the head at last became so large and heavy that it must have been too much for the body to bear, and so have led to its destruction! this conclusion, if sound, is a warning against carrying "specialisation" too far. if we wished to write an epitaph on the tomb of the monster, it ought (according to professor marsh) to be, "i and my race died of over-specialisation." [illustration: fig. .--bony spines belonging to the skin of _triceratops_. (after marsh.)] after all these various efforts to improve themselves and to perfect their organisation so as to bring it into harmony with their surroundings, or "environment," as the biologists say, it seems rather hard that the dinosaurs should have been extinguished, and their place in nature taken by a higher type; but all things have their day, even dinosaurs. with regard to the difficulties, hardships, and dangers attending the discovery and transport of the remains, professor marsh's concluding remarks may be quoted here, since they give us a glimpse into the nature of his explorations in the far west that have now become so famous. he says, "in conclusion, let me say a word as to how the discoveries here recorded have been accomplished. the main credit for the work justly belongs to my able assistant, mr. j. b. hatcher, who has done so much to bring to light the ancient life of the rocky mountain regions. i can only claim to have shared a few of the dangers and hardships with him, but without his skill little would have been accomplished. if you will bear in mind that two of the skulls weighed nearly two tons each, when partially freed from their matrix and ready for shipment, in a deep desert cañon, fifty miles from a railway, you will appreciate one of the mechanical difficulties overcome. when i add that some of the most interesting discoveries were made in the hunting-grounds of the hostile sioux indians, who regard such explorations with superstitious dread, you will understand another phase of the problem. i might speak of even greater difficulties and dangers, but the results attained repay all past efforts, and i hope at no distant day to have something more of interest to lay before you."[ ] [ ] _american journal of science_, vol. xli. p. . chapter viii. flying dragons. "geology does better in reclothing dry bones and revealing lost creations than in tracing veins of lead or beds of iron."--ruskin. the great ocean of air was not uninhabited during the long ages of the mesozoic era, when fishes swarmed in the seas, and reptiles, such as we have attempted to describe in the last five chapters, trod the earth, or swam across lakes and rivers. with such an exuberance of life in various forms, it would indeed have been strange if the atmosphere had only been tenanted by humble little insects like dragon-flies, locusts, or butterflies and moths, all of which we know were living then. now, the record of the rocks tells us that one great order of reptiles somehow acquired the power of flying, and flitted about as bats or flying-foxes do now. since they were undoubtedly reptiles--in spite of certain resemblances to birds--we have ventured to call them "flying dragons," as others have done. the notion of a flying reptile may perhaps seem strange, or even impossible to some persons; but no one has a right to say such and such a thing "cannot be," or is "contrary to nature," for the world is full of wonderful things such as we should have considered impossible had we not seen them with our eyes. charles kingsley, in his delightful fairy tale, _the water-babies_, makes some humorous remarks on that matter, which we may quote here. he says, "did not learned men too hold, till within the last twenty-five years, that a flying dragon was an impossible monster? and do we not now know that there are hundreds of them found fossil up and down the world? people call them pterodactyls; but that is only because they are ashamed to call them flying dragons, after denying so long that flying dragons could exist." the illustrious cuvier observes that it was not merely in magnitude that reptiles stood pre-eminent in ancient days, but they were distinguished by forms more varied and extraordinary than any that are now known to exist on the face of the earth. among these extinct beings of ages incalculably remote, are the pterodactyls,[ ] or "wing-fingered" creatures, which had the power of flight, not by a membrane stretched over elongated fingers as in bats, nor by a wing without distinct or complete fingers, as in birds, but by a membrane supported chiefly by a greatly extended little finger, the other fingers being short and armed with claws. [ ] from the greek--_pteron_, wing, and _dactylos_, finger. the only reptile now existing which has any power of sustaining itself in the air is the little _draco volans_, or "flying lizard," so called; but this can scarcely be regarded as a flying animal. its hinder pair of ribs, however, are prolonged to such an extent that they support a broad expansion of the skin, so spread out from side to side as to perform the office of a parachute, thus enabling the creature to spring from tree to tree by means of extended leaps; and this it does with wonderful activity. many forms of pterodactyl are known. some were not larger than a sparrow; others about the size of a woodcock; yet others much larger, the largest of all having a spread of wing (or rather of the flying membranes) of twenty-five feet! it has been concluded that they could perch on trees, hang against perpendicular surfaces, such as the edge of a cliff, stand firmly on the ground, and probably crawl on all fours with wings folded. it may be well at once to point out that the pterodactyl had no _true_ wings like those of a bird, but a thin membrane similar to that of a bat, only differently supported; so it must be understood that, when we use the word "wing," it is not in the scientific sense that we are using it, but in the popular sense, just as we might speak of the wing of a bat, although the bat has no true wing. figs. , , , and will give the reader some idea of the various forms presented by the skeletons of pterodactyls, or, as some authorities call them, pterosaurians (winged lizards). great differences of opinion have existed among palæontologists as to whether they are more reptilian than bird-like, or even mammalian. more than a hundred years ago, in , collini, who was director of the elector-palatine museum at mannheim, described a skeleton which he regarded as that of an unknown marine animal. it was a long-billed pterodactyl from the famous lithographic stone of solenhofen in bavaria. the specimen was figured in the _memoirs of the palatine academy_. collini was able from this specimen to make out the head, neck, small tail, left leg, and two arms; but beyond that, he was at a loss. his conclusion was that the skeleton belonged neither to a bat nor to a bird, and he inquired whether it might not be an amphibian. in this specimen came into cuvier's hands, who at once perceived that it belonged to a reptile that could fly, and it was he who proposed the name pterodactyl. until the oracle at paris was consulted, the greatest uncertainty prevailed, one naturalist regarding it as a bird, another as a bat. cuvier, with his penetrating eye and patient investigation, combated these theories, supported though they were by weighty authorities. the principal key by means of which he solved the problem, and detected the saurian relationship of the pterodactyl, seems to have been a certain bone belonging to the skull, known as the quadrate bone. in his great work, _ossemens fossiles_, he says, "behold an animal which, in its osteology, from its teeth to the end of its claws, offers all the characters of the saurians.... but it was, at the same time, an animal provided with the means of flight--which, when stationary, could not have made much use of its anterior extremities, even if it did not keep them always folded as birds keep their wings, which nevertheless might use its small anterior fingers to suspend itself from the branches of trees, but when at rest must have been ordinarily on its hind feet, like the birds again; and also, like them, must have carried its neck sub-erect and curved backwards, so that its enormous head should not interrupt its equilibrium." pterodactylus macronyx, or, as it is now called, dimorphodon macronyx (fig. ), was about the size of a raven. it was discovered in by the late miss mary anning, the well-known collector of fossils from the liassic rocks that form the cliffs alone: the coast of dorsetshire, near lyme-regis. this important specimen was figured and described by dr. buckland, in the _transactions of the geological society_. he suggested the specific name macronyx on account of the great length of the claws. [illustration: fig. --skeleton of _dimorphodon macronyx_. (after owen.)] this authority pointed out an unusual provision for giving support and power of movement to the large head at the extremity of a rather long neck, namely, the occurrence of fine long tendons running parallel to the neck-vertebræ. this does not occur in any modern lizards, whose necks are short, and require no such aid to support the head. they are a compensation for weakness that would otherwise arise from the elongation of the neck, supporting, as it did, such a large head. the neck-vertebræ in this species are large and strong, and capable of great flexibility forwards and backwards, so that the creature, by bending its neck during flight into the shape of an s, could throw its head back towards the centre of gravity. the restoration of the skeleton seen in the figure is by professor owen. it is probable that this pterodactyl could walk on the ground with its wings folded, and perhaps it was also capable of perching on trees, by clinging on to their branches with its feet and toes. when the flying membrane was stretched out it must, on account of the long tail to which it was also attached, have presented a triangular shape, somewhat like a boy's kite. [illustration: fig. .--skeleton of _scaphognathus crassirostris_. / natural size.] another genus, also from the lithographic slate of bavaria, namely, scaphognathus crassirostris (so called on account of its large beak and jaws), had a very short tail, and its skeleton looks somewhat clumsy for a creature adapted to fly through the air (fig. ). pterodactylus spectabilis, from the same strata, also possessed a very short tail, but has a more elegant and bird-like skull. this pretty little flying dragon was only about as large as a sparrow (see fig. ). its neck is comparatively short, with but few joints. the long slender beak was probably sheathed in horn, and the skull in several ways approaches that of a bird. since there are no teeth in the jaws, we may suppose that it devoured dragon-flies or other insects, such as we know were in existence during the period when the lithographic stone of bavaria was being deposited. those forms that were provided with teeth probably devoured such fishes as they could catch by swooping down upon the surface of the water. [illustration: fig. .--skeleton of _pterodactylus spectabilis_.] cuvier thought, from the magnitude of their eyes, that pterodactyls were of nocturnal habits. "with flocks of such creatures flying in the air, and shoals of no less monstrous ichthyosauri and plesiosauri swarming in the ocean, and gigantic crocodiles and tortoises crawling on the shores of the primæval lakes and rivers--air, sea, and land must have been strangely tenanted in these early periods of our infant world."[ ] [ ] buckland, _bridgewater treatise_. it was thought at one time that birds differed from pterodactyls in the absence of teeth; but this only holds good for modern birds. if we go back to the mesozoic age, we find that birds at that time did possess teeth. the oldest known bird, the archæopteryx, had teeth in its jaws, and presents some very striking points of resemblance to reptiles. but if we compare the skeleton of a pterodactyl (such as the p. spectabilis, now under consideration) with that of a bird, we shall see in its fore limbs certain very obvious differences. a bird never has more than three fingers in its hand or wing (viz. the thumb and next two digits), and the bones that support these fingers, corresponding to the bones in the palm of a human hand, are joined together. neither of the bones corresponding to our fingers are much elongated, and of these the longest is that which corresponds to the thumb. but, on referring to the skeleton of our pterodactyl, we find that it has four fingers, three of which are fairly developed and furnished with claws, while the outermost one is enormously elongated. this is believed to correspond to the little finger of the human hand, while the thumb seems to be represented by a small bone seen at the wrist. it was this long outside finger that chiefly served to support the flying membrane of the pterodactyl. for this and other reasons, we are forbidden to look upon these creatures as relatives of birds. again, all birds that can fly possess a "merrythought," or furculum; and such is not found in the pterodactyl. as we have already remarked, some authorities, when these creatures were first brought to light, considered them to be mammals, as bats are. but equally conclusive arguments may be brought forward against that view. all mammals have the skull jointed to the backbone by two articulations, known as "condyles," whereas pterodactyls have only one--in that respect resembling reptiles and birds. also there are important differences in the structure of their jaws, showing that they are constructed on the reptilian plan, and not on that of the mammal. in order to give rapid movement to their wings during flight, they had powerful muscles in the region of the chest. these were attached to a shield-like breast-bone provided with a keel--as in birds. but this bird-like feature is only a necessary provision to enable them to fly, and does not point to any relationship. [illustration: fig. .--skeleton of _rhamphorhynchus phyllurus_, with delicate impressions of the flying membranes. (after marsh.)] in the year was discovered, in the lithographic stone of bavaria, at eichstädt, a very beautiful new form of pterodactyl. this was the rhamphorhynchus phyllurus. the specimen is in a remarkable state of preservation; for the bones of the skeleton are nearly all in position, while those of both wings show very perfect impressions of the membranes attached to them. its long tail supported another small leaf-like membrane, which was evidently used as a rudder in flight (see fig. ). the discovery of this valuable specimen attracted much attention at the time. it was bought, by telegram, for professor marsh, and so secured for the yale college museum; but a cast may be seen at south kensington (wall-case, no. , gallery iv. on plan). any one who looks carefully at the beautiful impressions of the wings of this specimen can see that they must have been produced by a thin smooth membrane, very similar to that of bats. when this elegant little creature was covered up by the fine soft mud that now forms the lithographic stone, its wings were partly folded, so that the membranes were more or less contracted into folds, like an umbrella only partly open. these appear to have been attached all along the arm and to the end of the long finger. they then made a graceful curve backward to the hind foot, and probably were continued beyond the latter so as to join the tail. with its graceful pointed wings and long tail, this little flying saurian must have been a beautiful object, as it slowly mounted upwards from some cliff overlooking the jurassic seas. (see plate xii.) like those already described, it was provided with four short-clawed fingers, as well as the one which mainly supported its wing. some of the continental museums contain good collections of fossil pterodactyls; but the largest collection in the world is that of yale college, where professor marsh declares there are the remains of six hundred individuals from the american cretaceous rocks alone! [illustration: fig. .--skull of _pteranodon_. . side view. . top view. (after marsh.)] some of the fragmentary remains from our cambridge greensand formation indicate pterodactyls of enormous size. thus the neck-vertebræ of one species measure two inches in length, while portions of arm-bones are three inches broad. it is probable that the creatures to which these bones once belonged measured eighteen or twenty feet from tip to tip of the wings. other also fragmentary remains from the chalk of kent testify to the existence of pterodactyls during that period fully equal in size. but the largest pterodactyls hail, like so many other big things, from america. professor marsh tells us of monsters in his famous collection with a spread of wings of twenty to twenty-five feet! these large forms had no teeth in their jaws, and their skulls are of a peculiar form. the long-pointed jaws were probably sheathed in horn during life, as in birds (see fig. ). according to marsh, these toothless forms (which he calls pteranodonts) were mostly of gigantic size. with regard to their food it is almost vain to speculate; but if they _did_ prey upon fishes, they must have had a capacious mouth and gullet, and must have swallowed their prey whole, after the fashion of pelicans. but we doubt if they had the peculiar pouch possessed by those birds. in the absence of more complete accounts of the large forms the artist has only attempted to restore the small ones. (see plate xii., showing four different kinds.) [illustration: plate xii. group of small flying dragons, or pterodactyls. _rhamphorhynchus phyllurus._ _pterodactylus crassirostris. dimorphodon macronyx._ _pterodactylus spectabilis._] whether pterodactyls were cold-blooded or warm-blooded is a question on which the authorities are not agreed. professor owen argued from the absence of feathers that they could not have been warm-blooded. but, in spite of this great authority, who has defended his opinion somewhat strongly, there are others who argue that the amount of work involved in sustaining a pterodactyl in the air make it highly probable that it was warm-blooded. the absence of feathers to retain the heat of the body need not be regarded as conclusive, for bats are warm-blooded animals, and in their case the heat of the body is retained by a slight downy covering to the skin. such a covering may have protected the bodies of pterodactyls, and we could not expect to see any trace of it in the bavarian specimen of rhamphorhynchus referred to above. an important fact bearing on this question is the discovery of perforations in the bones of these animals very similar to those seen in birds. now, birds have a wonderful system of respiration, or breathing. the air they breathe passes, not into their lungs only, but penetrates to the remotest parts of their system, filling their very bones with life, and endowing them with activity and animation adapted to their active aërial existence. it may, therefore, be argued that pterodactyls breathed much in the same way; that their bones, too, were supplied with air by an elaborate system of air-sacs, and that they had lungs like those of birds. we cannot, however, stop there, but are led on by physiological reasoning to conclude that the circulation of the blood must have been rapid, and that the heart was like that of birds and mammals, four-celled. it would therefore follow--since birds and mammals are warm-blooded--that pterodactyls were also. such, at least, is the view of professor h. g. seeley, who says of the cambridge specimens, "that they lived exclusively upon land and in air is improbable, considering the circumstances under which their remains are found. it is likely that they haunted the sea-shores, and, while sometimes rowing themselves over the water with their powerful wings, used the wing-membranes, as the bat does, to enclose their prey, and bring it to the mouth. "the large cambridge pterodactyls probably pursued a more substantial prey than dragon-flies. their teeth are well suited for fish, but probably fowl and small mammals, and even fruits, made a variety in their food. as lord of the cliff, it may be presumed to have taken toll of all animals that could be conquered with tooth and nail. from its brain it might be regarded as an intelligent animal. the jaws present indications of having been sheathed with a horny covering." probably the large pterodactyls of the cretaceous period, soaring like albatrosses and giant petrels over the surface of the ocean, co-operated with the marine reptiles, such as ichthyosaurs, plesiosaurs, crocodiles, and others, as those sea-birds now do with the whales, porpoises, and dolphins, in reducing the excessive numbers of the teeming tribes of fishes, and in maintaining the balance of oceanic life. with regard to the place of pterodactyls in the animal kingdom, professor seeley places them as a distinct sub-class, side by side with birds, and between mammals and reptiles, thus-- mammalia. o r n i t a h v o e s s a u r i a reptilia. the name ornithosauria (bird-lizards) is frequently used instead of the other name, because it expresses the idea of their being partly saurian, and partly bird-like. they flourished from the period of the lias to that of the chalk; and then, like so many other strange forms, seem to have suddenly disappeared. chapter ix. sea-serpents. "sand-strewn caverns, cool and deep, where the winds are all asleep; where the spent lights quiver and gleam, where the salt weed sways in the stream; where the sea-beasts, ranged all round, feed in the ooze of their pasture-ground; where the sea-snakes coil and twine, dry their mail, and bask in the brine." _the forsaken merman._ it has been said that everything on earth has its double in the water. are there not water-beetles, water-scorpions, water-rats, water-snakes, sea-lions, sea-horses, and a host of other living things, whether plants or animals, bearing some sort of resemblance to others that live on land? then why not sea-serpents? the great controversy of the sea-serpent, that has so often been discussed in the newspapers, need not be considered here. we are dealing not with the present, but with the past; and whether or no the wonderful sailors' yarns of sea-serpents can be regarded as authentic, even in a single case, we can offer our readers infallible proof that, during the so-called "age of reptiles," certain monstrous saurian animals flourished in considerable abundance, which, though not true serpents, nevertheless must have borne a striking resemblance to such, as they cleaved he waters of primæval seas.[ ] [ ] see an interesting little work, entitled, _sea-monsters unmasked_, by h. lee (clowes and sons). appendix ii. contains some extracts therefrom. the modern evolutionist believes that snakes are descended from lizards, possessing, as usual, four legs; that some primitive form of lizard with very small legs appeared on the scene, and found that it could better move along by wriggling its body and pushing with its ribs than by walking. so, in course of time, a race of lizards without legs arose; these, by natural selection, and perhaps other means, became more and more elongated, so that they could move faster than their ancestors, and glide out of harm's way more effectually. thus was the snake evolved from a lizard. now, in the great geological museum of the stratified rocks, there have been discovered skeletons of marine reptiles, which propelled themselves chiefly by means of their tails and elongated bodies, rather than by their limbs. the limbs were not discarded entirely as in the case of the serpents, but were useful in their way as the fins of fishes are. perhaps, therefore, we may be justified in calling these ancient monsters sea-serpents, in consideration of their long thin bodies; for they certainly would be called by that name if now living. strictly speaking, they were not serpents, but more or less like some of the extinct saurians described in chap. iv. the name, however, has been adopted by geologists, and is useful in so far as it serves to remind us of their very peculiar shape and structure. remains of these strange creatures have been found both in europe and america. one of the earliest discoveries of remains of a fossil sea-serpent was made by m. hoffman, a dutch military surgeon, in the year . maestricht, a city in the interior of the netherlands, situated in the valley of the meuse, stands on certain strata of limestone and sandstone, belonging to the upper chalk. extensive quarries have, for many centuries, been worked in the sandstone, especially in the eminence called st. peter's mount, which is a cape or headland between the meuse and the jaar. this elevated plateau extends for some distance towards liége, and presents an almost perpendicular cliff towards the meuse. from the extensive works that have so long been carried on, immense quantities of stone have been removed, and the centre of the mountain is traversed by galleries, and hollowed by vast excavations. innumerable fossils, such as marine shells, corals, crustaceans, bones and teeth of fishes, have been obtained from this rock. but st. peter's mount is now chiefly celebrated for the discovery of the bones and teeth of a huge saurian, to which mr. conybeare has given the name mosasaurus, on account of its connection with the river meuse. m. hoffman had long been an assiduous collector of fossils from this neighbourhood, and he had the good fortune to obtain the famous specimen on which this genus is founded. it was at first considered, by m. faujas st. fond, to be a crocodile; but cuvier and camper formed a different and better conclusion. perhaps no fossil ever had such a remarkable history as this one, as the following account, from m. faujas st. fond's work on the fossils of st. peter's mount,[ ] will show. [ ] _histoire naturelle de la montagne de st. pierre._ this account is given by dr. mantell, in his _petrifactions and their teaching_, . "some workmen, on blasting the rock in one of the caverns of the interior of the mountain, perceived, to their astonishment, the jaws of a large animal attached to the roof of the chasm. the discovery was immediately made known to m. hoffman, who repaired to the spot, and for weeks presided over the arduous task of separating the mass of stone containing these remains from the surrounding rock. his labours were rewarded by the successful extrication of the specimen, which he conveyed in triumph to his house. this extraordinary discovery, however, soon became the subject of general conversation, and excited so much interest, that the canon of the cathedral which stands on the mountain resolved to claim the fossil, in right of being lord of the manor; and succeeded, after a long and harassing lawsuit, in obtaining this precious relic. it remained for years in his possession, and hoffman died without regaining his treasure, or receiving any compensation. at length the french revolution broke out, and the armies of the republic advanced to the gates of maestricht. the town was bombarded; but, at the suggestion of the committee of savans who accompanied the french troops to select their share of the plunder, the artillery was not suffered to play on that part of the city in which the celebrated fossil was known to be preserved. in the mean time, the canon of st. peter's, shrewdly suspecting the reason why such peculiar favour was shown to his residence, removed the specimen, and concealed it in a vault; but when the city was taken, the french authorities compelled him to give up his ill-gotten prize, which was immediately transmitted to the jardin des plantes, at paris, where it still forms one of the most striking objects in that magnificent collection." dr. mantell quotes the frenchman's remark on this transaction: "_la justice, quoique tardive, arrive enfin avec le temps_:" but adds, "the reader will probably think that, although the reverend canon was justly despoiled of his ill-gotten treasure, the french commissioners were but very equivocal representatives of _justice_!" the beautiful cast (fig. ) at south kensington (fossil reptile gallery, wall-case ) was presented to dr. mantell by baron cuvier in . it consists of both jaws, with numerous teeth, and some other parts (see fig. ). the length is about four and a half feet. this nearly perfect head was for a time a stumbling-block to many naturalists, some of whom were of opinion that it belonged to a whale. cuvier and others considered it to be a kind of link between the iguanas and the monitors.[ ] [ ] the monitors are a family of large lizards inhabiting the warmer parts of africa and asia. they live near the banks of rivers, and some are altogether aquatic. they often devour the eggs of crocodiles and aquatic birds. the nile monitor, or varanus, grows to a length of six feet. [illustration: fig. .--skull of _mosasaurus hoffmanni_. the original is - / ft. by - / ft.] [illustration: fig. .--teeth of mosasaurus (half natural size). ^a, ^a, transverse sections of the teeth.] the entire backbone of the maestricht animal appears to have consisted of one hundred and thirty-one vertebræ, of which ninety-seven belonged to the tail. the total length of the skeleton is estimated at twenty-four feet, and the head was about one-sixth of the total length. the tail is only ten feet long, whereas in a crocodile the tail exceeds the length of the body. although in his day the limbs of the mosasaurus were imperfectly known, cuvier rightly considered them to be adapted for swimming, and, with his usual foresight, concluded that this monster was a marine reptile of great strength and activity, having a large tail flattened vertically and capable of being moved from side to side with such force and rapidity as to be a powerful organ of propulsion, capable of stemming the most agitated waters. the large conical recurved teeth, the largest of which was nearly three inches long, are well seen in figs. and . dr. mantell was fortunate enough to find, in the year , some vertebræ from the english chalk near lewes, which were identified as belonging to a mosasaurus. in a portion of a lower jaw with large conical teeth was discovered in the chalk near norwich. but these teeth were not quite similar to those of the maestricht specimen, and professor owen therefore founded upon them the new genus leiodon.[ ] but leiodon must have been very similar to mosasaurus. [ ] greek--_leios_, smooth, and _odous_, tooth. [illustration: fig. .--lower tooth of _leiodon_. . side view. . profile.] of late years many fine specimens have been discovered in north america, and the labours of leidy, marsh, and cope have been of the greatest service in completing our knowledge of this strange group of saurians. in the american cretaceous seas they ruled supreme, as their numbers, size, and carnivorous habits enabled them easily to vanquish all rivals. probably some of them were seventy-five feet in length, the smallest being ten or twelve feet long. in the inland cretaceous sea from which the rocky mountains were beginning to emerge, these ancient sea-serpents abounded; and many were entombed in its muddy deposits. on one occasion, as professor marsh rode through a valley washed out of this old ocean bed, he observed no less than seven different skeletons of these monsters in sight at once! the same authority mentions that the museum of yale college contains remains of not less than distinct individuals. in some of these the skeleton is nearly if not quite complete; so that every part of its structure can be determined with almost absolute certainty. according to professor cope of pennsylvania university, who has made a special study of this group of extinct saurians, fifty-one species have been discovered in north america, in the states of new jersey, alabama, kansas, north carolina, mississippi, and nebraska. the same authority has shown that they were characterised by a wonderful elongation of form, especially of the tail; that their heads were large, flat, and conical in shape, with eyes directed partly upward; that they were furnished with two pairs of paddles like the flippers of a whale. with these flippers, and the eel-like strokes of their flattened tail, they swam with considerable speed. like snakes, they were furnished with four rows of formidable teeth on the roof of the mouth, which served admirably for seizing their prey. but the most remarkable feature in these creatures was the arrangement for permitting them to swallow their prey whole, in the manner of snakes. thus each half of the lower jaw was articulated at a point nearly midway between the ear and the chin, so as to greatly widen the space between the jaws, and professor cope thinks that the throat must consequently have been loose and baggy. professor cope, however, in giving the name pythonomorpha to this ancient group, has pressed his views too far, and dwelt unduly on their supposed relationship with serpents. other authorities regard them as essentially swimming lizards, with four well-developed paddles; and this is probably the right view to take of them. the following graphic account of the region where professor cope has discovered the skeletons of many sea-serpents, and of their habits and aspect when alive, is taken from his well-known work on the cretaceous vertebrata of the west.[ ] after describing this region as a vast level tract between the missouri and the rocky mountains, he says, "if the explorer searches the bottoms of the rain-washes and ravines, he will doubtless come upon the fragment of a tooth or jaw, and will generally find a line of such pieces leading to an elevated position on the bank or bluff, where lies the skeleton of some monster of the ancient sea. he may find the vertebral column running far into the limestone that locks him in his last prison; or a paddle extended on the slope, as though entreating aid; or a pair of jaws lined with horrid teeth, which grin despair on enemies they are helpless to resist; or he may find a conic mound, on whose apex glisten in the sun the bleached bones of one whose last office has been to preserve from destruction the friendly soil on which he reposed. sometimes a pile of huge remains will be discovered, which the dissolution of the rock has deposited on the lower level; the force of rain and wash having been insufficient to carry them away." [ ] _report of the united states geological and geographical survey of the territories_, vol. ii., (_cretaceous vertebrata_). [illustration: plate xiii. group of sea-serpents, elasmosaur, and fishes. fishes, _portheus_. _elasmosaurus._ length feet. _beryx._ _clidastes._ length feet. _osmeroides_, etc. _mosasaurus._ length feet.] but the reader inquires, "what is the nature of these creatures thus left stranded a thousand miles from either ocean? how came they in the limestone of kansas, and were they denizens of land?" these creatures lived in the cretaceous period. the remains found in this region were mostly those of reptiles and fishes. thirty-five species of reptiles are known from kansas alone, representing six orders, and varying in length from ten to eighty feet. one was terrestrial, four were fliers, the rest inhabited the ocean. "when they swam over what are now the plains, the coast-line extended from arkansas to near fort riley, on the kansas river, and, passing a little eastward, traversed minnesota to the british possessions, near the head of lake superior. the extent of sea to the westward was vast, and geology has not yet laid down its boundary; it was probably a shore now submerged beneath the waters of the north pacific." other very elongated marine reptiles of this period, but with much thicker bodies, are called, by professor cope, elasmosaurs. in this group, which is not yet fully worked out, occur such genera as cimoliosaurus, polycotylus, polyptychodon, and others. but it seems a pity that they should be in any way separated from the plesiosaurs, which they strongly resemble (see chap. iv., plate iii.). though not sea-serpents, we have introduced them here because they flourished at the same time, and lived in the same seas with the mosasaurs and other forms of that group. the very large teeth, with strongly marked ridges, of the polyptychodon are abundant in the cambridge greensand that underlies the chalk, and represent a very huge animal. in our illustration, plate xiii., the artist has represented the elasmosaurus[ ] (of cope) with its long thin neck stretched out in search of food on the bed of the sea. professor cope--thus describing this monster, in language which seems somewhat fanciful--says, "far out on the expanse of this ancient sea might have been seen a huge snake-like form, which rose above the surface, and stood erect, with tapering throat and arrow-shaped head, or swayed about, describing a circle of twenty feet radius above the water. then plunging into the depths, naught would be visible but the foam caused by the disappearing mass of life. should several have appeared together, we can easily imagine tall, flexible forms rising to the height of the masts of a fishing-fleet, or like snakes twisting and knotting themselves together. this extraordinary neck--for such it was--rose from a body of elephantine proportions. the limbs were probably two pairs of paddles, like those of plesiosaurus, from which this diver chiefly differed in the arrangement of the bones of the breast. in the best-known species twenty-two feet represent the neck in a total length of fifty feet. this is elasmosaurus platyurus (cope), a carnivorous sea-reptile, no doubt adapted for deeper waters than many of the others. like the snake-bird of florida, it probably often swam many feet below the surface, raising the head to the distant air for breath, then withdrawing it, and exploring the depths forty feet below, without altering the position of its body. from the localities in which the bones have been found in kansas, it must have wandered far from land; and that many kinds of fishes formed its food is shown by the teeth and scales found in the position of its stomach." [ ] greek--_elasmos_, plate; _sauros_, lizard: probably on account of the shape of the paddles. but to return to the sea-serpents. mosasaurus is now known to have been a long slender reptile, with a pair of powerful paddles in front, a moderately long neck, and flat pointed head. the tail was very long--flat and deep--like that of a great eel. mosasaurus princeps is computed to have been seventy-five to eighty feet long. clidastes was another genus of long and slender shape, one species of which reached a length of forty feet. some forms of sea-serpent had sclerotic plates in the eye, such as we found in the fish-lizard, or ichthyosaurus (p. ), but the announcement that their bodies were protected by bony plates has turned out to be a mistake, and the supposed plates really belonged to the eye. leiodon proriger (cope) was abundant in the old north american cretaceous sea, and reached a length of seventy-five feet. it had a long projecting muzzle, somewhat like the snout of a sturgeon. platecarpus and tylosaurus had peculiarly sharp-pointed heads (see fig. ). [illustration: fig. .--snout of tylosaurus. (after marsh.)] a few words may be added here with regard to professor cope's important discovery of leiodon--a genus already alluded to as having been founded by sir richard owen. the type specimen of leiodon dyseplor,[ ] which first indicated the characters of this wonderful species, was obtained from the yellow beds of the niobrara epoch of the jornada del muerto, near fort mcrae, new mexico. the greater part of the remains have been described by professor leidy. but a second specimen, more complete in all respects, was discovered by professor cope's exploring party during an expedition from fort wallace, kansas, in . this specimen he has fully described and figured in the report already referred to (p. ). it is a very instructive specimen, including fifty of the vertebræ from all parts of the vertebral column, a large part of the cranium, with teeth, as well as important limb-bones. these precious relics were excavated from a chalk "bluff," or high bank. fragments of the jaws were seen lying on the slope, and other portions entered the shale. on being followed, a part of the skull was taken from beneath the roots of a bush, and the vertebræ and limb-bones were found farther in. the series of vertebræ, after extending some way along the face of the bluff, finally turned into the hill, and were followed as far as time would permit, but part of the tail series had to be left. in size, the vertebræ of this enormous sea-serpent exceed those of mosasaurus brumbyi. the latter has hitherto been the largest known species of the order of pythonomorphs, exceeding twofold in its measurements the m. giganteus of belgium. so the present reptile is much larger in its dimensions than the new jersey species called maximus by professor cope. "if, as appears certain," says the professor, "the mosasauroid discovered by webb measures seventy-five feet in length, and the m. maximus measured eighty, the leiodon dyspelor must have been the longest reptile known, and approaches very nearly the extreme of the mammalian growth seen in the whales, though, of course, without their bulk. such monsters may well excite our surprise, as well as our curiosity, in the inquiry as to their source of food-supply, and what the character of those contemporary animals preserved in the same geologic horizon." [ ] we retain the old spelling with the _e_ as being nearer to the greek, although professor cope writes it "liodon." in our illustration, plate xiii., the artist has endeavoured to realise the outward aspect of the two genera of sea-serpents, mosasaurus and clidastes. the fishes which they are pursuing are well-known genera from the english chalk, such as beryx. ten species of clidastes have been unearthed from the kansas strata. they did not reach such a size as the leiodons, but were of elegant and flexible build, the largest species, c. cineriarum, reaching a length of forty feet (see fig. ). a smaller species, of elegant proportions, has been called c. tortor (cope). its slenderness of body was remarkable, and the large head was long and lance-shaped. its lithe movements doubtless helped it to secure many fishes. it was found coiled up beneath a ledge of rock, with its skull lying undisturbed in the centre. the accounts given by professor cope of his explorations and the difficulties encountered in procuring the valuable specimens on which his conclusions are based, are most interesting, and such as every fossil-hunter will appreciate. we, in england, who visit clay pits, stone quarries, railway cuttings, etc., during a morning or an afternoon walk, and return home at our leisure with a few small specimens in our pockets, or in a bag at our back, can hardly realise how arduous must be the work of finding, digging out, and transporting for such long distances the remains of the monsters of kansas and other parts of north america. [illustration: fig. .--skeleton of _clidastes cineriarum_; length feet. (after cope.)] the following extracts have been selected from professor cope's report, with a view to illustrating the nature of the explorations undertaken. "the circumstances attending the discovery of one of these will always be a pleasant recollection to the writer. a part of the face, with teeth, was observed projecting from the side of a bluff by a companion in exploration, lieutenant james h. whitten, united states army, and we at once proceeded to follow up the indication with knives and picks. soon the lower jaws were uncovered, with their glistening teeth, and then the vertebræ and ribs. our delight was at its height when the bones of the pelvis and part of the hind limb were laid bare, for they had never been seen before in the species, and scarcely in the order. while lying on the bottom of the cretaceous sea, the carcase had been dragged hither and thither by the sharks and other rapacious animals, and the parts of the skeleton were displaced and gathered into a small area. the massive tail stretched away into the bluff, and, after much laborious excavation, we left a portion of it to more persevering explorers." "the discovery of a related species, platecarpus coryphæus (cope), was made by the writer under circumstances of difficulty peculiar to the plains. after examining the bluffs for half a day without result, a few bone fragments were found in a wash above their base. others led the way to a ledge forty or fifty feet from both summit and foot, where, stretched along in the yellow chalk, lay the projecting portions of the whole monster. a considerable number of vertebræ were found preserved by the protective embrace of the roots of a small bush, and, when they were secured, the pick and knife were brought into requisition to remove the remainder. about this time, one of the gales, so common in that region, sprang up, and striking the bluff fairly, reflected itself upwards. so soon as the pick pulverised the rock, the limestone dust was carried into eyes, nose, and every available opening in the clothing. i was speedily blinded, and my aid disappeared in the cañon, and was seen no more while the work lasted. a handkerchief tied over the face, and pierced by minute holes opposite the eyes, kept me from total blindness, though dirt in abundance penetrated the mask. but a fine relic of creative genius was extracted from its ancient bed, and one that leads its genus in size, and explains its structure." [illustration: fig. _a_.--skull of _platecarpus_. upper cretaceous. north america. (after cope.)] "on another occasion, riding along a spur of yellow chalk bluff, some vertebræ lying at its foot met my eye. an examination showed that the series entered the rock, and, on passing round to the opposite side, the jaws and muzzle were seen projecting from it, as though laid bare for the convenience of the geologist. the spur was small and of soft material, and we speedily removed it in blocks, to the level of the reptile, and took out the remains as they lay across the base from side to side." in taking leave of the "age of reptiles," we cannot but marvel greatly at the diversity of forms assumed by the various orders of this class, their strange uncouth appearance, their assumption, in some cases, of characters only known at the present day among the mammals, their great abundance, and the perfect state in which their remains have been preserved in the stratified rocks of various parts of the world. and the reader may naturally ask, "how is it that so many types have disappeared altogether, leaving us out of a total of at least nine orders, only four, viz. those represented by crocodiles, lizards, snakes, and turtles?" to such a question we can only answer that the causes of the extinction of plants and animals in the past are not yet known. climate, geographical conditions, food-supply, competition, with other causes, doubtless operated then as now; but if there is one clear lesson taught by the record of the rocks, it is this--that there has been at work from the earliest periods a law of progress, so that higher types, coming in at certain stages, have ousted the lower types, sometimes only partially, sometimes completely. but why the dinosaurs, for instance, perished entirely, while the crocodiles survived to the present day, no one can yet explain. we can see no reason, however, why such problems as these should not be solved in the future by the co-operating labours of naturalists and geologists. in the great onward and upward struggle for existence, higher types have supplanted lower ones; and, in accordance with this biological truth, we find that in the next era (known as the tertiary or cainozoic) the mammal held the field while the reptile took a subordinate place. chapter x. some american monsters. "geology, in the magnitude and sublimity of the objects of which it treats, ranks next to astronomy in the scale of the sciences."--sir john f. w. herschel. with the advent of the cainozoic or tertiary era, we enter upon the "age of mammals," when great quadrupeds suddenly came upon the scene. the place of the reptile was now taken by the mammal. in the long previous era this higher type of life was not altogether wanting, but as far as the geological record is yet known, it appears only to have been represented by a few primitive little creatures, probably marsupials, whose jaw-bones have been discovered in the new red sandstone, and the stonesfield oolite.[ ] [ ] the english cretaceous rocks, previously thought to be destitute of mammalian remains, have quite recently yielded teeth belonging to some small mammal. these were found in wealden strata. geology tells of a great gap between the highest rocks of the cretaceous period and the lowest group of the succeeding eocene period (see table of strata, appendix i.). this gap, or break, testifies to a very long interval of time during which important geographical and other changes took place; and consequently we find in eocene rocks (at the base of the cainozoic series) a very different fauna and flora to that which is preserved in the chalk formation. the researches of cuvier among the fossils collected from eocene rocks in the neighbourhood of paris, especially the gypseous series of montmartre, revealed the existence of a very extensive fauna, especially of new types of mammals; and his restoration of the palæotherium, a tapir-like animal, and other forms, created a vast amount of interest, and greatly stimulated the study of extinct animals. as we have already remarked, the science of palæontology may be said to have been founded by cuvier (see introduction, p. ). but now the scene shifts once more from europe to the wilds of the far west. american geologists tell us that a long time ago (during the eocene period) there was a great tropical lake in the wyoming territory, on the borders of which roamed, amidst luxuriant vegetation, a large number of strange and primitive quadrupeds, together with many other forms of life. the most wonderful group of animals that haunted the shores of this lake, or series of lakes, was the dinocerata so fully described by professor marsh, in his exhaustive monograph.[ ] the name implies that they were terrible horned monsters, but whether nature provided them with true horns, like those of horned cattle to-day, is at least open to doubt. [ ] _the dinocerata_, a monograph by o. c. marsh, _united states geological survey_, vol. x. fig. shows the skeleton of one of these, namely, tinoceras ingens. its length was about feet without the tail. its weight, when alive, is calculated to have been six thousand pounds, or about two tons and three quarters. plate xiv. is a restoration of the tinoceras, made by our artist, after much consideration and careful study of the valuable cast exhibited in the natural history museum at south kensington, which was generously presented by professor marsh (gallery i. case mm on plan). in planning this and other restorations, both artist and author have received valuable assistance from dr. henry woodward, f.r.s., keeper of the geological department of the museum, who is ever ready to help with his great knowledge those who come to consult him. there may be differences of opinion among palæontologists as to the appearance presented by this formidable creature when alive, and no doubt the nature of the skin must always be more or less a matter of conjecture in such cases, but we venture to hope that the restoration here given, based as it is upon mr. smit's thorough acquaintance with living animals and professor marsh's description, will meet with a favourable verdict. [illustration: fig. .--skeleton of _tinoceras ingens_. (after marsh.)] looking at the skeleton, one is struck with a certain resemblance to the rhinoceros on one hand, and to the elephant on the other. the legs are very elephantine, and the feet must have been covered with thick pads, but the body reminds one more of the rhinoceros; and yet, again, there is some suggestion of the hippopotamus. the eye was small and deep set, as in the rhinoceros. in the upper jaw the two canine teeth are developed into dagger-shaped tusks, the use of which can only be conjectured. in the females these are but slightly developed. [illustration: plate xiv. a large extinct mammal, tinoceras ingens. from north america. length about feet (without the tail).] it is quite clear, then, that we cannot place the dinoceras in any order of living mammals. it is what palæontologists call a "generalised type;" that is to say, it presents certain characters seen in several groups of living quadrupeds, and not any of those elaborated or highly developed parts which we see in such animals to-day. thus the proboscis of the elephant is a greatly elongated nose; in other words, the elephant is highly "specialised" in that direction, whereas our dinoceras had no proboscis, or only a very slight one. [illustration: fig. .--skull of _dinoceras mirabile_. (after marsh.)] again, the six remarkable bony protuberances of the skull served to some extent as horns, and probably were covered with thick bosses of skin, and did not support true horns like those of our modern oxen and other ruminants. speaking of these protuberances, professor marsh says, "none of the covering of these elevations, or horn-cores, has, of course, been preserved; yet a fortunate discovery may perhaps reveal their nature by the form of a natural cast, as the eye-ball of the oreodon is sometimes thus clearly indicated in the fine miocene matrix which envelops these animals." it looks rather as if we have here an early stage in the evolution of horns, and it may be that in the course of subsequent ages such prominences as those developed into true "horn cores," such as sheep or goats have, while the thick bosses of skin that covered them slowly developed into the true horns that are attached to these cores. if this is so, then we have here another instance of a "generalised" structure. again, the limbs with their five toes tell us at once that the creature's place in nature is outside of those two great groups of modern ungulates, or hoofed quadrupeds, the odd-toed and the even-toed, represented on the one hand by the horse, rhinoceros, and tapir, on the other by the pig, camel, deer, ox, and many other forms. probably the two groups had not at this early period branched off from the primitive ungulate stock with five toes in each foot, of which the elephant is a living descendant, and from which also the dinoceras must have come. [illustration: fig. .--cast of brain-cavity of _dinoceras mirabile_. (after marsh.)] the limbs were strong and massive, but the brain was remarkably small, so that our dinoceras cannot be credited with any high degree of intelligence: and here again we see an absence of "specialisation" compared with the sagacious elephant. professor marsh has taken casts of its brain-cavity (see fig. ). these casts show that the brain was smaller (in proportion to the size of the animal) than in any other mammal, whether living or extinct--and even less than in some reptiles! in fact, it was a decidedly reptilian kind of brain. perhaps it may seem hardly credible, but so small was the brain of dinoceras mirabile, that it could have been pulled through the apertures (neural canals) of all the neck vertebræ! in certain marsupials of the present day we find an approach to this kind of brain. it seems to be an established fact, according to professor marsh, that all the eocene or earlier tertiary mammals had small brains. his researches among fossil mammals have led him to the important conclusion that, as time went on, the brains of mammals grew larger; and thus he has been able to establish his law of brain-growth during the tertiary period, a law which appears to be plainly recorded in the fossil skulls of succeeding races of ancient mammals. the importance of a discovery such as this cannot fail to strike the imagination of even the most unlearned in geology as being singularly suggestive and instructive. it is not difficult to picture these dull, heavy, slow-moving creatures haunting the forests and palm jungles around the margin of the great eocene lake, into the waters of which their carcases from time to time found their way--perhaps swept down by floods. no footprints have been discovered as yet. the dinocerata were very abundant for a long time during the middle of the eocene period. the position of their remains suggests that they lived together in herds, as cattle do now, and they probably found an abundance of food in the shape of succulent vegetation round the great lake. geological evidence points to their sudden extinction before the close of the eocene period; but it is difficult to understand this. professor marsh thinks that from their sluggish nature they were incapable of adapting themselves with sufficient rapidity and readiness to new conditions, such as may have been brought about by geographical changes. it must be admitted, however, that the geological record in this region does not give evidence of any sudden change. possibly they may only have migrated to some other region, where their remains have not yet been discovered, or where, for various reasons, their skeletons were not preserved. in this eocene lake, where sediments went on being quietly deposited for a long time, we have the most favourable conditions for the preservation of the different forms of life that flourished round its borders. in the museum at yale college are collected the spoils of numerous expeditions to the west, and the many tons of bones lying there are believed to represent the remains of no less than two hundred individuals of the dinocerata. so perfectly have these bones been preserved by nature that, even if the creatures had been living now, the material for studying their skeletons could hardly be more complete. professor marsh recognises three distinct types in this strange group of quadrupeds, on each of which a genus has been founded. the first and oldest form is the uintatherium, which takes its name from the uinta mountains. this, as might be expected, is the most primitive or least specialised form, and comes from lower strata. the most highly developed or specialised form is the tinoceras, and this is found at the highest geological level or "horizon." between these two extremes, and from an intermediate horizon, comes the dinoceras,[ ] so that in tracing these animals through the strata in which they occur the geologist finds that he is following for a while the course of their evolution. doubtless there were many slight differences presented by the members of this group, but at present it has not been found possible to determine the number of species, although about thirty forms more or less distinct have been recognised. professor marsh says that the specimen of the skull of dinoceras mirabile, on which the whole order dinocerata was founded, is, fortunately, in a very perfect state of preservation, and that it belonged to a fully adult animal. moreover, it was embedded in so soft a matrix that the brain-cavity and the openings leading from it could be worked out without difficulty. in removing the skull from the rock, on the high and almost inaccessible cliff where it was found, two or three important fragments were lost; but professor marsh, after a laborious search, recovered them from the bottom of a deep ravine, where they had been washed down and covered up. [ ] the dinoceras of marsh is the same form as eobasileus of cope. uintatherium was discovered by leidy. it is about twenty-two years since the wonderful forms of life sealed up within these eocene lake-deposits first became known to science. long before then, however, the wandering indian had been accustomed to seeing strange-looking skulls and skeletons that peeped out upon him from the sides of cañons and hills, as the rocks that enclosed them crumbled away under the influence of atmospheric agents of change--the ceaseless working of wind, rain, heat, and cold. to his untrained mind no other explanation suggested itself than the idea that these were the bones of his ancestors, which it would be highly impious to disturb. _requiescant in pace!_ so he left them in peace. perhaps he believed in a former race of human giants; if so, these would be their bones. long before professor marsh's expeditions, the earliest squatters, trappers, and others used to bring back news of marvellous monsters grinning from the ledges of rock beneath which they camped. at last these tales attracted the notice of some enthusiastic naturalists in the eastern states. professor leidy obtained a number of bones, from which he was able to bring to light an extinct creature at that time unknown to science, namely, the uintatherium. professor cope also described some extinct animals disinterred by himself from the same region. but our knowledge of the dinocerata is chiefly due to professor marsh, who has despatched one expedition after another, and who, after many years of laborious research both in the western deserts and in his wonderful collection at yale college, has published a splendid monograph on the subject. no trouble and no expense have been spared in order to obtain material for this great work, and all geologists must feel grateful to professor marsh for so liberally devoting his time and his private resources in order to advance the science of palæontology. the region in which the remains occur of the remarkable group of extinct animals now under consideration, has a peculiar scenery of its own, unlike anything in europe. the following graphic description of its features is from the pen of sir archibald geikie:--[ ] [ ] _nature_, vol. xxxii. p. . "on the high plateau that lies to the west of the rocky mountains, along the southern borders of the wyoming territory, the traveller moving westwards begins to enter on peculiar scenery. bare, treeless wastes of naked stone, rising here and there into terraced ledges and strange tower-like prominences, or sinking into hollows where the water gathers in salt or bitter pools. under the cloudless sky, and in the clear dry atmosphere, the extraordinary colouring of these landscapes forms, perhaps, their weirdest feature. bars of deep red alternate with strips of orange, now deepening into sombre browns, now blazing out again into vermilion, with belts of lilac, buff, pale green, and white. and everywhere the colours run in almost horizontal bands, running across hollows and river-gorges for mile after mile through this rocky desert. the parallel strips of colour mark the strata that cover all this wide plateau country. they are the tints characteristic of an enormous accumulation of sedimentary rocks, that mark the site of a vast eocene lake, or succession of lakes, on what is now nearly the crest of the continent." in this strange region the flat-topped hills, table-lands, or terraces, as they are variously named, seen from lower levels, are usually called "buttes," especially when they are of limited extent. this name is of french origin, and signifies a bank of earth or rising ground. it is also applied in a limited sense to the more prominent irregularities of the deeply sculptured slopes of the larger terraces. these buttes, therefore, vary in extent, from a mere mound rising slightly above the level of the plains to hills of varied configuration reaching to the level of the broader buttes or terraces. the _débris_ resulting from the continual wearing away, or demolition of these buttes and terraces, now lies spread out on the plains below. from the lower plains the smaller terraces appear like vast earth-work fortifications, and when not too much cut up by erosion, remind one of long railway embankments. but in many cases the terraces are so much cut up by narrow ravines that they appear as great groups of naked buttes rising from the midst of the plain. nothing can be more desolate in appearance than some of these vast assemblages of crumbling buttes, destitute of vegetation, and traversed by ravines, in which the watercourses in midsummer are almost all dried up. to these assemblages of naked buttes, often worn into castellated and fantastic forms, and extending through miles and miles of territory, the early canadian _voyageurs_ gave the name _mauvais terres_. they occur in many localities of the tertiary formations west of the mississippi river. professor leidy, who with two friends made an expedition in search of fossils to dry creek cañon in this region of the "bad lands," about forty miles to the southeast of fort bridger (wyoming), thus describes his impressions:-- "on descending the butte to the east of our camp, i found before me another valley, a treeless barren plain, probably ten miles in width. from the far side of this valley butte after butte arose and grouped themselves along the horizon, and looked together in the distance like the huge fortified city of a giant race, the utter desolation of the scene, the dried-up watercourses, the absence of any moving object, the profound silence which prevailed, produced a feeling that was positively oppressive. when i thought of the buttes beneath our feet, with their entombed remains of multitudes of animals for ever extinct, and reflected upon the time when the country teemed with life, i truly felt that i was standing on the wreck of a former world." these old lake-basins, in which so many forms of life have been sealed up, all lie between the rocky mountains on the east, and the wasatch range on the west, or along the high central plateau of the continent. as the mountains were slowly elevated, part of the old sea of the cretaceous period (that sea in which the "sea-serpents" played so important a part) was enclosed and cut off from the ocean. rivers began to pour their waters into it, so that the waters became less and less salt, until at last a fresh-water lake, or series of lakes, was formed. as the upward movement of this region continued these lakes were all the while receiving sedimentary materials, such as sand and mud, from the rivers, until finally they were filled up, but not until the sediments had formed a mass of strata over a mile in thickness. thus we see how favourable were the conditions for a faithful record of eocene life-history. but another process was going on which helped to bring them to an end; for they were being slowly drained by the rivers that flowed out of them, and these rivers kept on continually deepening their channels, so that we have dry land where the lakes once were. _now_ the region is over feet above the sea, and probably more than one-half of these fresh-water deposits have been washed away, mainly through the colorado river. what is left of the eocene strata forms the "bad lands." the same geological action that has cut up and carved out this region into buttes, cañons, cliffs, peaks, and columns of fantastic shapes, has also brought to light the extinct animals preserved in the rocks, much in the same way as an old burial-ground, if cut up by intersecting trenches, might be made to yield up the bones of those who for generations had been buried therein. professor marsh first discovered remains of dinocerata in , while investigating this eocene lake-basin, which had never before been explored. it was here, also, that he found the wonderful series of fossil horses by means of which he has been able to prove that our modern horse is descended from a small quadruped with five toes, and to show the different stages in its evolution. here, also, were found old-fashioned types of carnivorous quadrupeds, of rodents, and of insectivorous creatures. but reptiles as well as quadrupeds flourished on the borders of the old lake, for the remains were found of crocodiles, tortoises, lizards, and serpents; its waters, too, were well stocked with fish. everything here testifies to a long continuance of those conditions under which plant and animal life can flourish, namely, a warm climate, plenty of food, and freedom from those physical changes which, by altering the geographical features of a country, bring so many important consequences in their train. the geological record tells us that this happy state of things lasted all through the eocene period, and until the fresh-water lakes had at last been drained away by their outflowing rivers. in october, , a later eocene lake-basin was discovered by the same exploring party, and this professor marsh calls the uinta basin, because it was situated south of the uinta mountains. "in the attempt to explore it," he says, "our party endured much hardship, and also were exposed to serious danger, since we had only a small escort of united states soldiers, and the region visited was one of the favourite resorts of the uinta-utes. these indians were then, many of them, insolent and aggressive, and since have been openly hostile, at one time massacring a large body of government troops sent against them. two subsequent attempts ... to explore this region met with little success." this lower lake was of later (or upper) eocene age, and the extinct animals preserved in its ancient bed appear to resemble more nearly those of the famous paris basin, referred to in the beginning of this chapter, than any yet discovered in america. but the basin north of the uinta mountains, where alone the dinocerata had been found, offered so inviting a field that, in the spring of , professor marsh began to explore it systematically. he organised an expedition, with an escort of u.s. soldiers, and the work continued during the whole season. in this way a large collection was secured. explorations were continued in the spring of the following year, which resulted in the discovery of the type specimen of the dinoceras mirabile. another expedition was organised in , also with an escort of soldiers, and a great many specimens were collected. these researches were continued during , and again in , with good results. since then various small parties have been equipped and sent out by professor marsh to collect in the same region of the "bad lands;" and, finally, during the entire season of , the work was vigorously prosecuted under his direction, and afterwards under the auspices of the united states geological survey. this brief account of the difficulties and hardships encountered by professor marsh and his companions, for which we are indebted to his exhaustive monograph, will serve to give some idea of the nature of those labours, undertaken in the cause of science, which he has brought to so successful an issue. * * * * * in the country east of the rocky mountains, including the states of dakota, nebraska, wyoming, and part of colorado, professor marsh has discovered the remains of yet another strange group of large quadrupeds. the best known of these is brontops, of which the skeleton is seen in fig. . these animals lived after the dinocerata, namely, in the miocene period, and were the largest american mammals of that period. they constitute a distinct family more nearly allied to the rhinoceros than to any other living form. the skeleton on which fig. is founded was the most complete of any yet discovered by professor marsh. portions of it were exhumed at different times, but it was first found in . our artist has made the restoration seen in plate xv. from this skeleton, as figured by professor marsh. [illustration: plate xv. a huge extinct mammal from north america. brontops robustus.] this strange group of creatures flourished in great numbers on the borders of an old lake of miocene age. the brontops was a heavy massive animal, larger than any of the dinocerata, with a length of twelve feet, not including the tail, and a height of eight feet. the limbs are shorter than those of the elephant, which it nearly equalled in size. as in the tapir, there were four toes to the front limbs, and three to the hind limbs. its skull was of a peculiar shape, shallow, and very large. that of brontops ingens is thirty-six inches long, and twenty inches between the tips of the two horns, or protuberances. the creature was probably provided with an elongated, flexible nose, like that of the tapir, but not longer, because the length of the neck shows that it could reach the ground without the aid of a trunk such as the elephant's. it is doubtful if the two prominences on the front of the skull were provided with horns, for, if directed forwards, they would interfere with the animal when grazing. [illustration: fig. .--skeleton of brontops robustus. (after marsh.)] chapter xi. some indian monsters. "what a glorious privilege it would be, could we live back--were it but for an instant--into those ancient times when these extinct animals peopled the earth! to see them all congregated together in one grand natural menagerie--these mastodons and elephants, so numerous in species, toiling their ponderous forms and trumpeting their march in countless herds through the swamps and reedy forests!"--hugh falconer. it is a far cry back, against the sun's path, from wyoming and the flanks of the rocky mountains to the sacred himalayas--the "abode of snow"--of northern india. but if the reader will follow us to that country, we will endeavour to describe two or three out of many strange and now lost forms of life brought to light from the famous sivalik hills, on the southern border of the himalayas, for the knowledge of which science is greatly indebted to a very distinguished palæontologist, the late mr. hugh falconer. together with his friend captain cautley (afterwards sir proby cautley), he explored this region, and their joint arduous labours show that it was at one time inhabited by a very large and varied group of quadrupeds, together with many birds, reptiles, fishes, mollusca, and crustaceans. in this region there lived, throughout a considerable part of the tertiary period, elephants, of various species, whose skulls and bones were found in great numbers; mastodons (a closely allied form); and several species of hippopotamus, rhinoceros, and horse: among ruminants, species of the camel, the ox, the stag, and the antelope, together with a colossal creature unknown before, the sivatherium, which has never been found elsewhere; a huge tortoise, and various species of carnivora, rodents, and apes. with regard to the geography of the region, it appears that the continent of india, at an early period of the tertiary era, was a large island, situated in a bight, or bay, formed by the himalayas and the hindoo koosh range. the valleys of the ganges and indus formed a long estuary, into which the drainage of the himalayas poured its silt and alluvium. later on, an upheaval took place, converting these straits into the plains of india, connecting them with the ancient island, and forming the existing continent. the large and varied forms whose remains now lie "sealed within the iron hills" then spread over the continent, from the irrawaddi to the mouths of the indus, two thousand miles; and north-west to the jhelum, fifteen hundred miles. after a long interval of repose, another great upheaval took place, which threw up a strip of the plains of india, crumpled and ridged it up to form the sivalik hills, and at the same time increased the elevation of the himalayas by many thousands of feet. it would be easy to show that such events as these must have been followed by changes in climate, for the climate of a region depends largely on its physical features--the proportion of land and water, the presence of hills and mountain ranges, and their height; and it is considered probable that the physical changes above mentioned helped to bring about the extinction of this most interesting and ancient fauna. throughout the latter part of the tertiary era it is well known to geologists that the climate of europe was becoming gradually colder, until at last a glacial period, or "ice age," was experienced, during which northern europe was subjected to an arctic climate, and the great ice-sheet seems to have been slowly retiring and melting away in the early part of the stone age. but in india there has been no such decrease in temperature, and it enjoyed in tertiary times as warm a climate as it now has, so that both animal and vegetable life continued to flourish vigorously. by the sivalik (or sewalik) hills is meant that range of lower elevations which stretches along the south-west foot of the himalayas, for the greater portion of their extent from the indus to the brahmapootra, where those rivers respectively debouche from the hills into the plains of india. it extends for nearly a thousand miles, and it appears to have been entirely built up of alluvial _débris_, washed down from the himalayas into that sea which we have already referred to as having once separated the plains of india from the great range now forming its northern boundary. the strata thus formed were subsequently upheaved to form the sivalik hills. thus we see that one mountain range may help to form another one running parallel to itself. the name is derived from siva, or mahadeo, the hindoo god; these hills, as well as the himalayas, being connected in hindoo mythology in various ways with the history of siva. dr. falconer and captain cautley soon found that they had "struck oil" in the sivalik hills, or, in other words, had come upon one of nature's great graveyards, full of material most valuable to the palæontologist--one which, extending for hundreds of miles, might perhaps prove to be as rich in relics of the world's "lost creations" as the lake-basin in wyoming, where professor marsh discovered his dinocerata and other extinct types. let us give dr. falconer and captain cautley their due. they found themselves suddenly confronted with a perfect mine of wealth, in a far country, where the ordinary means resorted to by men of science for determining extinct types and species, by comparison with living forms, were not to be obtained, for there were no libraries and no museums of comparative anatomy in that remote quarter of india. but dr. falconer was not the man to be baffled by such drawbacks, which would have deterred and discouraged some men. he appealed to the living forms that abounded in the surrounding forests, rivers, and swamps, and took toll of them to supply the want. nature herself became his library and his museum. skeletons of all kinds were prepared; the extinct forms he collected were compared with their nearest living allies, and a valuable series of "memoirs" by himself and captain cautley was the result.[ ] [ ] these appeared in the _asiatic researches_, the _journal of the asiatic society of bengal_, and in the _geological transactions_ of the london geological society. the sivalik explorations soon attracted attention in europe, and in the wollaston medal, in duplicate, was awarded for their discoveries to dr. falconer and captain cautley by the geological society, the fountain of geological honours in england; while the value of the distinction was enhanced by the terms in which the president, sir charles lyell, was pleased to announce the award. this is what he said: "when captain cautley and dr. falconer first discovered these remarkable remains, their curiosity was awakened, and they felt convinced of their great scientific value; but they were not versed in fossil osteology [the study of bones], and, being stationed on the remote confines of our indian possessions, they were far distant from any living authorities or books on comparative anatomy to which they could refer. the manner in which they overcame these disadvantages, and the enthusiasm with which they continued for years to prosecute their researches, when thus isolated from the scientific world, are truly admirable. dr. royle has permitted me to read a part of their correspondence with him, when they were exploring the sivalik mountains, and i can bear witness to their extraordinary energy and perseverance. from time to time they earnestly requested that cuvier's works might be sent out to them, and expressed their disappointment when, from various accidents, these volumes failed to arrive. the delay, perhaps, was fortunate; for, being thrown entirely upon their own resources, they soon found a museum of comparative anatomy in the surrounding plains, hills, and jungles, where they slew the wild tigers, buffaloes, antelopes, and other indian quadrupeds, of which they preserved the skeletons, besides obtaining specimens of all the reptiles which inhabited that region. they were compelled to see and think for themselves, while comparing and discriminating the different recent and fossil bones, and reasoning on the laws of comparative osteology, till at length they were fully prepared to appreciate the lessons which they were taught by the works of cuvier." in captain cautley presented his vast collection, the result of ten years' unremitting labour and great personal outlay, to the british museum, the geological society having declined to accept it, as it was beyond their means of accommodation. its extent and value may be estimated from the fact that it filled large chests, the average weight of each of which amounted to cwt., and that the charges on its transmission to england alone, which were defrayed by the government of india, amounted to £ . dr. falconer's selected collection was divided between the india house and the british museum; the greater part was presented to the former, but a large number of unique or choice specimens, required to fill up blanks, were presented to the latter. the greater part of the specimens in the british museum were still unarranged and embedded in their matrix. in a memorial was presented to the court of directors of the honourable east india company, pointing out the desirability of having the specimens in the national collection prepared, arranged, and displayed, and also of publishing an illustrated work, which would convey to men of science in both hemispheres a knowledge of the contents of the sivalik hills, and suggesting dr. falconer as the person most fitted to superintend the work. the government of the time, under sir robert peel, made a grant of £ to enable the collection to be exhibited in the british museum, and dr. falconer was entrusted with the work. besides this, a large illustrated work, entitled _fauna antiqua sivalensis_, was begun, but owing to the demands upon dr. falconer's time, and his subsequent death, this work was not completed, although nine out of the twelve parts originally contemplated were finished. the great indian collection of fossils, mainly the gift of sir proby cautley (the specimens of which, stupendous in their size, and in fine preservation, were prepared, identified, and arranged by dr. falconer), has long constituted one of the chief ornaments of the collection at the british museum--now removed to the natural history museum, cromwell road, south kensington. other collections of fossils from the sivalik hills have been presented to the museum of edinburgh university by colonel colvin, and to the oxford university by mr. walter ewer. when it is remembered that these collections have since been increased tenfold, and that the remains were either excavated or found in the _débris_ of cliffs, and that the explored surface bears a very small proportion to that which has not yet been investigated, one may conceive how prodigious must have been the number of animals that lived together in the former plains of india, even when every allowance is made for the bones having accumulated during many successive generations in the sivalik strata. from this large and important collection we select two of special interest for brief notice here, namely, the sivatherium,[ ] and an immense tortoise known as the colossochelys. [ ] from _siva_, the hindoo god; and greek, _therion_, a beast. the first of these monsters was a remarkable form of animal, unlike anything living. in size it surpassed the largest rhinoceros, and was bigger than any living ruminant. altogether, it was one of the most remarkable forms of life yet detected in the more recent strata. it had two pairs of horns on its head--two short and quite simple ones in front, and two larger ones, more or less expanded, behind them. from the character of these long horn-cores, which are prolongations of the skull, it may be concluded that the sivatherium was a gigantic ruminant with four horns. a cast of the original skull, with the horn-cores restored from actual parts, in the collection and elsewhere, has been placed on a stand in the centre of the long gallery of fossil vertebrates at south kensington (stand i) near to the case containing the skull and other portions of the skeleton (see fig. ). there is also hanging on the wall near, a clever painting by berjeau, representing the creature as it may have appeared when alive. the entire skeleton, partly restored, is shown in fig. , with a conjectural outline of the body. a hornless skull of a nearly allied animal from the same strata and locality is placed with that of the sivatherium, and was considered by dr. falconer and others to be the skull of the hornless female (also represented as such in the above picture referred to); but is now, by more recent writers, regarded as a separate genus, viz. the helladotherium, so named because the remains were first discovered at pikermi, near athens, greece (ancient hellas). (see plate xvi.) [illustration: fig. .--skull of _sivatherium giganteum_, from the sivalik hills, northern india.] [illustration: plate xvi. a gigantic hoofed mammal, sivatherium giganteum. from the sivalik hills, northern india. an allied form, _helladotherium_, is seen on the left] in the sivatherium we have a new type which seems to connect together two families at the present time well marked off from each other, namely, the giraffe and the antelope. its teeth resemble those of the former animal, while in its four horns it resembles a certain antelope (antilope quadricornis). the head in certain respects shows resemblances to that of the ox, but the upper lip must have been prolonged into a short proboscis, or trunk, like that of the tapir. the form and proportions of the jaw agree closely with the corresponding parts of a buffalo. but no known ruminant, fossil or existing, has a jaw of such large size, the average dimensions being more than double those of a buffalo. the skull is the best known part of the animal, but captain cautley came across some of the bones of the limbs. [illustration: fig. .--skeleton of _sivatherium giganteum_.] the colossochelys atlas,[ ] or gigantic fossil tortoise of india, supplies a fit representative of the tortoise which sustained the elephant and the infant world in the fables of the pythagorean and hindoo cosmogonies. it is highly interesting to trace back to its probable source a matter of belief like this, so widely connected with the speculations of an early period of the human race. [ ] greek, _colossos_, colossus, and _chelus_, tortoise. atlas was supposed to sustain the world on his shoulders. the carapace, or buckler, of the shell of this crawling monster is similar in general form to the large land-tortoises of the present day.[ ] the shell is estimated to have been at least six feet long. the limbs were probably similar to those of a modern land-tortoise, and the limb-bones are of huge size--a single humerus, or arm-bone, measuring inches. probably the foot was as large as that of a rhinoceros. a restored cast of a young individual stands at the west end of the fossil reptile gallery, south kensington (stand z on plan). length of the shield, feet[ ] (see fig. ). [ ] giant tortoises of the present day live on islands--where they have escaped competition with large carnivora and other foes--such as the aldabra group, n.w. of madagascar, in the mascarenes, which comprise mauritius and rodriguez; and the galapagos, or "tortoise islands," off the coast of south america. when mr. darwin visited the latter islands he saw the relics, as it were, of a family of huge tortoises, which lived there in abundance a few years before, and was able to verify many interesting facts which had been recorded by porter in , who stated that some of those captured by him weighed from to lbs., and that on one island they were - / feet long. those of one island differed from those of another. some had long necks. after mr. darwin's visit the process of extermination went on. at the present time it is most probable that the gigantic tortoises are very rare where formerly they were so abundant. one of these great tortoises is that of abingdon island, in the galapagos archipelago, of which there is a fine stuffed specimen in the natural history museum (reptile gallery). it has a very long neck, and a small flat-topped head with a short snout. it weighed originally lbs. the indian tortoises of the present day are not of large size. see the fine specimens in the natural history museum--reptile gallery (left wing of the building). [ ] dr. falconer's estimate was much too great, so that this model is too large. mr. lydekker prefers to drop the generic term colossochelys, and call it testudo atlas. in length it was only one-third greater than testudo elephantina of the galapagos islands. the first fossil remains of this colossal tortoise were discovered by dr. falconer and captain cautley in , in the tertiary strata of the sivalik hills. at the period when it was living--probably the pliocene--there was great abundance and variety of life on the scene, for its remains were found to be associated with those of many great quadrupeds, such as the elephant, mastodon, rhinoceros, horse, camel, giraffe, sivatherium, and many other mammals. the sivalik fauna also included a great number of reptiles, such as crocodiles, lizards, and snakes. [illustration: fig. .--restored figure of gigantic tortoise, _colossochelys atlas_, from the sivalik hills, northern india.] the greater part of the remains of the colossochelys atlas were collected during a period of eight or nine years, along a range of about a hundred miles of hilly country. consequently, they belong to a large number of individuals, varying in size and age. they were met with in crushed fragments, contained in upheaved strata, which have undergone considerable disturbance, so that it is improbable that an entire uncrushed specimen will ever be found. when the first fragments, in huge shapeless masses, were found by the discoverers, they were utterly at a loss what to make of them, and for many months could do nothing more than look upon them in bewildered and nearly hopeless admiration. but no sooner was the clue found to a single specimen than every fragment moved into its place so as to form a consistent whole. it is not possible at present to say, with any degree of certainty, whether this colossal tortoise survived into the human period; but at least there is no evidence against the idea, and dr. falconer shows it is quite possible that the frequent allusions to a gigantic tortoise in hindoo and other mythologies are to be explained on the supposition that the creature was seen by the men of a prehistoric age. other species of tortoises and turtles that were coeval with the colossochelys have lived on to the present day. so have other reptiles, for some of the crocodiles now living in india appear to be identical with the forms dug out of the sivalik hills. in the absence of direct geological evidence, we must fall back on traditions. now, there are traditions connected with the speculations of nearly all eastern nations with regard to the world (cosmogonies) that refer to a tortoise of such gigantic size as to be associated with the elephant in their fables. the question therefore arises--was this tortoise a creature of the imagination, or was the idea of it drawn from a living reality? besides a tradition current among the iroquois indians of north america, referring to the important share which the tortoise had in the formation of the earth, there are several cases in ancient history bearing on the same point. thus, we find in the pythagorean doctrine the infant world represented as having been placed on the back of an elephant, which was sustained on a huge tortoise. greek and hindoo mythologies were undoubtedly related to each other, and accordingly we find in the hindoo accounts of the second avatar of vishnoo, that the ocean is said to have been churned by means of the mountain placed on the back of the king of the tortoises, and the serpent asokee used as the churning-rope. again, vishnoo was said to have assumed the form of the tortoise, and to have sustained the created world on his back to make it stable. this fable has taken such a firm hold of the hindoos, that to this day they believe the world rests on the back of a tortoise (see fig. ). in the narratives of the feasts of the bird-demigod, garuda, the tortoise again figures largely, and guruda is said on one occasion to have appeased his hunger at a certain lake where an elephant and a tortoise were fighting. [illustration: fig. .--the elephant victorious over the tortoise, supporting the world, and unfolding the mysteries of the _fauna sivalensis_. from a sketch in pencil in one of dr. falconer's note-books, by the late professor edward forbes.] these three instances, in each of which there is a distinct reference to a gigantic form of tortoise, comparable in size with the elephant, suggest the question whether we are to regard the idea as a mere fiction of the imagination, like the minotaur or the chimæra, or as founded on a living tortoise. dr. falconer points out that it seems unlikely that such fables could have been suggested by any of the small species of tortoises now living in india, and consequently is inclined to think that the monster was seen by man many centuries ago, long before he began to write history. we have already alluded to the large number of mammalian forms of life that were contemporary with the sivatherium and colossochelys, but if we examine this old sivalik fauna we find it presents several very interesting features. in the first place, it exhibits a wonderful richness and variety of forms, compared to the living fauna of india. take the pachydermata, for instance--an old order established by cuvier to include the rhinoceros, hippopotamus, elephant, etc.--and we find there were, in the period under consideration, about five times the number of species now known in india. elephants and mastodons, too, of various species abounded. so it is with the ruminants; besides a large number of species allied to those now living, such as the ox, buffalo, bison, deer, antelope, musk-deer, and others, there were giraffes and camels, as well as the strange sivatherium. and so it is with the other orders, such as carnivora, rodents, insectivora, etc. secondly, this great and varied fauna of the past shows a striking resemblance to that of india at the present day. darwin found the same resemblance in south america; and now it is accepted as a general law, that the living fauna of a country resembles its extinct fauna, especially that of the latest geological period. dr. falconer found that india's living fauna is but, as it were, a remnant of that which it once possessed. thirdly, this extinct sivalik fauna presents a singular mixture of old and new forms. and lastly, it points to a very different geographical distribution of animals. thus the giraffe, the hippopotamus, and the ostrich are _now_ confined to africa. facts such as these serve to throw light on the geography of the past; but we cannot stay to enlarge on that subject here. much might be said about the fossil elephants and mastodons from the sivalik hills, so fully described by dr. falconer, but since chapters xiii. and xiv. deal with elephants, we must reserve our remarks till then, only alluding here to one striking form from the sivalik hills, namely, the elephas ganesa, the tusks of which were more than ten feet in length, and much less curved than those of the mammoth. a very fine specimen of the head and tusks may be seen in the gallery of fossil mammals in the natural history museum (gallery i, stand d). with the following eloquent passage from dr. falconer's "memoirs," we take leave of the remarkable sivalik fauna, hoping that future geologists will endeavour to follow his example and bring to light yet other "lost creations" from that region, so rich in fossils, yet comparatively unexplored. would that the english government could see their way to follow the example of the united states, and send out a scientific expedition to explore this wonderful region! there can be no doubt that a rich harvest lies waiting there to be reaped. "what a glorious privilege it would be, could we live back--were it but for an instant--into those ancient times when these extinct animals peopled the earth! to see them all congregated together in one grand natural menagerie--these mastodons and elephants, so numerous in species, toiling their ponderous forms and trumpeting their march in countless herds through the swamps and reedy forests! to view the giant sivatherium, armed in front with four horns, spurning the timidity of his race, and, ruminant though he be, proud in his strength, and bellowing his sturdy career in defiance of all aggression! and then the graceful giraffes, flitting their shadowy forms like spectres through the trees, mixed with troops of large as well as pigmy horses, and camels, antelopes, and deer! and then, last of all, by way of contrast, to contemplate the colossus of the tortoise race, heaving his unwieldy frame, and stamping his toilsome march along plains which hardly look over strong to sustain him! "assuredly it would be a heart-stirring sight to behold! but although we may not actually enjoy the effect of the living pageant, a still higher order of privilege is vouchsafed to us. we have only to light the torch of philosophy, to seize the clue of induction, and, like the prophet ezekiel in the vision, to proceed into the valley of death, when the graves open before us and render forth their contents; the dry and fragmented bones run together, each bone to his bone; the sinews are laid over, the flesh is brought on, the skin covers all, and the past existence--_to the mind's eye_--starts again into being, decked out in all the lineaments of life. 'he who calls that which hath vanished back again into being, enjoys a bliss like that of creating.' such were the words of the philosophical niebuhr, when attempting to fill up the blanks in the fragmentary records of the ancient romans, whose period in relation to past time dates but as of yesterday. how much more highly privileged, then, are we, who can recall, as it were, the beings of countless remote ages, when man was not yet dreamed of! not only this, but if we use discreetly the lights which have been given to us, we may invoke the spirit of the winds, and learn how _they_ were tempered to suit the natures of these extinct beings." chapter xii. giant sloths and armadillos. "injecta monstris terra dolet suis." horace, _odes_, book iii. it would have been strange, considering how much we owe to north america, had the great south american continent not enriched our knowledge of past forms of life on the globe. but such is not the case. the honours are, as it were, divided, although it must be admitted that the north american extinct forms at present known are far more numerous. there are, however, two or three "extinct monsters" of very great interest which once had a home in south america--in that strange region of the pampas, where the naturalist of the present day finds so much to excite his interest. of these the present chapter treats. the megatherium[ ] (cuvier) was a gigantic mammal allied to sloths and ant-eaters, and perhaps to the armadillos. in its skull and teeth this colossus of the past resembled the sloths, in its limbs and backbone it resembled the ant-eaters, while in size it surpassed the largest rhinoceros (plate xvii.). the famous, but imperfect, specimen at madrid was for a long time the principal if not the only source of information with regard to this extinct genus, and for nearly a century it remained unique. [ ] greek--_megas_, great; _therion_, beast. later on, however, the zeal and energy of sir woodbine parish, his late majesty's _chargé-d'affaires_ at buenos ayres, greatly helped to augment the materials for arriving at a just conclusion with regard to its proper place in the animal kingdom. according to one writer, spain formerly possessed considerable parts of three different skeletons. the first and most complete is that which is preserved in the royal cabinet at madrid. this was sent over in , by the marquis of loreto, viceroy of buenos ayres, with a notice stating that it was found on the banks of the river luxan. in a second specimen arrived from lima, and other portions, probably not very considerable, were in the possession of father fernando scio, to whom they had been presented by a lady from paraguay. but two german doctors, messrs. pander and d'alton, who published in a beautiful monograph on the subject, state that they were unable in to find any traces of either the lima specimen or that which had belonged to fernando scio. the remains collected by sir woodbine parish were discovered in the river salado, which runs through the flat alluvial plains (pampas) to the south of the city of buenos ayres, after a succession of three unusually dry seasons, "which lowered the waters in an extraordinary degree, and exposed parts of the pelvis to view as it stood upright in the bottom of the river."[ ] [ ] "some account of the remains of the _megatherium_ sent to england from buenos ayres, by woodbine parish, jun., esq., f.r.s.," by wm. clift, esq., f.r.s., _geological transactions_, second series, vol. iii. p. . [illustration: plate xvii. cast of a skeleton of megatherium americanum. set up in the natural history museum.] this and other parts having been carried to buenos ayres by the country people, were placed at the disposal of sir woodbine parish by don hilario sosa, the owner of the property on which the bones were found. a further inquiry was instituted by sir woodbine; and on his application, the governor granted assistance, the result of which was the discovery of the remains of two other skeletons on his excellency's properties, at no great distance from the place where the first had been found. it was in the year that sir woodbine parish sent his valuable collection of bones from buenos ayres, and presented them to the royal college of surgeons. these specimens formed the subject of mr. clift's memoir above quoted. but even then the materials were not complete for a thorough knowledge of the bony framework of the megatherium, and it was not till , when more remains (discovered near luxan, ) reached this country, that professor owen was able to clear up one or two doubtful details. these were purchased by the trustees of the british museum, and casts of the bones were taken. among the various writings by learned men on the subject, professor owen's masterly description stands pre-eminent; indeed, he was the only one to solve the riddle, to thoroughly explain the structure of this giant sloth, and to show how its food was obtained.[ ] neither cuvier, nor the german doctors, nor mr. clift had succeeded in so doing. [ ] his views are expounded in his _memoir on the megatherium, or giant ground sloth of america_, , which is beautifully illustrated. the royal society gave £ (part of a government grant of £ ) to enable professor owen to carry out this important work. in the natural history museum (stand o, gallery no. on plan) is a cast representing the animal nearly erect, and grasping a tree. this magnificent cast (see plate xvii.) represents an animal eighteen feet in length, and its bones are more massive than those of the elephant. for instance, the thigh-bone is nearly thrice the thickness of the same bone in the largest of existing elephants, the circumference being equal to the entire length. to a comparative anatomist several striking indications of great strength present themselves; thus, not only the very forms of the bones themselves mean strength, but their surfaces, ridges, and crests are everywhere made rough for the firm attachment of powerful muscles and tendons. in the fore part of the body the skeleton is _comparatively_ slender, but the hind quarters show enormous strength and weight combined. the tail, also, is very powerful and massive. the fore limbs are long, and evidently constructed for the exertion of great force. how this force was applied we shall see presently. in both sets of limbs we notice powerful claws, such as might be used for scratching up the ground near the roots of a tree, and it was at one time thought that this was the way in which the creature obtained its leafy food, namely, by digging up trees by the roots and then devouring the leaves. but professor owen had another explanation. as in the living sloths and armadillos (edentata[ ]), there are no teeth in the fore part of the jaw. the molar teeth, of which there are five on each side of the upper jaw, and four in the lower, are hollow prismatic cylinders, straight, seven to nine inches long, and implanted in deep sockets. there are no other teeth, but these are composed of different substances, and so arranged that, as the tooth wears, the surface always presents a pair of transverse ridges, thus producing a dental apparatus well suited for grinding up vegetable food. in the elephants, which live on similar food, the grinding is effected by great molar teeth, which are replaced by new ones as the old ones are worn away. in the megatherium, however, only _one_ set of teeth was provided; but these, by constant upward growth, and continual addition of new matter beneath, lasted as long as the animal lived, and never needed to be renewed. [ ] this word, which means _toothless_, is misleading. all the edentata, however, agree in having no front, or incisor, teeth. on looking at the model so skilfully set up at south kensington, and especially at the front part of the skull, it will be seen that the snout and lips must have been somewhat elongated, possibly into a slight proboscis like that of the tapir. the specimens of the lower jaw in the wall-case close by show that it was much prolonged and grooved. this fact must be interpreted to mean that the creature possessed a long and powerful tongue, aided by which it could, like the giraffe, strip off the small branches of the trees which it had broken or bent down within its reach. a bony shield (or carapace) of a great armadillo was found with one of the specimens described by mr. clift, and buckland and others thought it belonged to the megatherium; but owen afterwards showed, by most clear and convincing reasoning from the skeleton, that the megatherium could not have been protected as armadillos are, by such a shield (see p. ). [illustration: plate xviii. great ground-sloth of south america, megatherium americanum. length feet.] and now we come to the question how it obtained its food. the idea of digging round trees with its claws in order to uproot them, must be partly, if not entirely, given up; for professor owen has proved, by a masterly piece of reasoning, that this cumbrous creature, instead of climbing up trees as modern sloths do, actually pulled down the tree bodily, or broke it short off above the ground by a _tour de force_, and, in order to do so, sat up on its huge haunches and tail as on a tripod, while it grasped the trunk in its long powerful arms! marvellous as this may seem, it can be shown that every detail in its skeleton agrees with the idea. of course there would be limits to possibilities in this direction, and the larger trees of the period must have been proof against any such samson-like attempts on the part of the megatherium; but when the trunk was too big, doubtless it pulled down some of the lower branches. plate xviii. is a restoration, by our artist, of the south kensington skeleton. speaking of the extinct sloths of south america, mr. darwin thus describes professor owen's remarkable discovery: "the habits of these megatheroid animals were a complete puzzle to naturalists until professor owen solved the problem with remarkable ingenuity. their teeth indicate by their simple structure that these animals ... lived on vegetable food, and probably on the leaves and small twigs of trees; their ponderous forms and great strong curved claws seem so little adapted for locomotion, that some eminent naturalists believed that, like sloths, to which they are intimately related, they subsisted by climbing, back downwards, on trees, and feeding on the leaves. it was a bold, not to say preposterous, idea to conceive even antediluvian trees with branches strong enough to bear animals as large as elephants. professor owen, with far more probability, believes that, instead of climbing on trees, they pulled the branches down to them, and tore up the smaller ones by the roots, and so fed on the leaves. the colossal breadth and weight of their hinder quarters, which can hardly be imagined without having been seen, become, on this view, of obvious service instead of being an encumbrance; their apparent clumsiness disappears. with their great tails and huge heels firmly fixed like a tripod in the ground, they could freely exert the full force of their most powerful arms and great claws."[ ] [ ] _journal of researches._ to this we may add dean buckland's description,[ ] "his entire frame was an apparatus of colossal mechanism, adapted exactly to the work it had to do; strong and ponderous in proportion as this work was heavy, and calculated to be the vehicle of life and enjoyment to a gigantic race of quadrupeds, which, though they have ceased to be counted among the living inhabitants of our planet, have, in their fossil bones, left behind them imperishable monuments of the consummate skill with which they were constructed. each limb and fragment of a limb form coordinate parts of a well-adjusted and perfect whole." [ ] _bridgewater treatise._ after reading these descriptions, it is not difficult to form a mental picture of the great beast laying siege to a tree, and to conceive the massive frame of the megatherium convulsed with the mighty wrestling, every vibrating fibre reacting upon its bony attachment with the force of a hundred giants; extraordinary must be the strength and proportions of the tree if, when rocked to and fro, to right and left, in such an embrace, it can long withstand the efforts of its assailant. it yields, the roots fly up, the earth is scattered wide upon the surrounding foliage, and the tree comes down with a thundering crash, cracking and snapping the great boughs like glass. then the coveted food is within reach, and the giant reaps the reward of his herculean labours. sir woodbine parish thought that the megatherium fed on the agave, or american aloe. another form of extinct sloth found in the same region is the mylodon. though of smaller size, it was much bigger than any living sloth, and attained a length of eleven feet. it has the same general structure, but the head and jaws are somewhat different, and more like the recent forms. a nearly perfect and original skeleton of mylodon gracilis has been set up beside its huge relative's cast in the same gallery at the natural history museum. the crowns of its molar teeth are flat instead of being ridged; hence its name, which signified "mill-toothed." yet another was the scelidotherium[ ] with its long limbs. darwin obtained an almost entire skeleton of one of these. it was as large as a polar bear. speaking of his discovery, he says, "the beds containing the fossil skeletons consist of stratified gravel and reddish mud; a proof that the elevation of the land has been inconsiderable since the great quadrupeds wandered over the surrounding plains, and the external features of the country were then very nearly the same as now. the number of the remains of these quadrupeds embedded in the vast estuary deposits which form the pampas and cover the granitic rocks of banda oriental must be extraordinarily great. i believe a straight line drawn in any direction through the country would cut through some skeleton or bones. as far as i am aware, not one of these animals perished, as was formerly supposed, in the marshes or muddy river-beds of the present land, but their bones have been exposed by the streams intersecting the subaqueous deposit in which they were originally embedded. we may conclude that the whole area of the pampas is one wide sepulchre of these extinct gigantic quadrupeds."[ ] [ ] greek--_scelis_, limb; _therion_, beast. [ ] _journal of researches._ the genus scelidotherium comprises a number of species and presents characters more or less intermediate between megatherium and some other genera. the skull is low and elongated, and shows an approach to that of the modern ant-eater. the feet also are different from those of megatherium (see fig. ). [illustration: fig. .--skeleton of _scelidotherium_. (after capellini.)] these monster sloths inhabited south america during the latest geological period, known as the pleistocene. during part of that time north america, as well as northern europe and asia, were invaded by a great ice-sheet, and an arctic climate prevailed. it is therefore very probable that while the mammoth and the mastodon were roaming over north america, giant sloths and armadillos were monarchs of the southern continent. what cause, or causes, led to the extermination of the giant sloths and armadillos is still a matter of speculation. one writer suggests an explanation that seems to deserve consideration. the southern parts of this great continent are even now subject to long-continued droughts, sometimes lasting for three years in succession, and bringing great destruction to cattle. in fact, the discoveries related above were rendered possible by several successive dry seasons. it is argued that the upright position of most of the skeletons found _in situ_ seems to suggest that the creatures must have been mired in adhesive mud sufficiently firm to uphold the ponderous bones after the flesh had decayed. a long drought would bring the creatures from the drained and parched country to the rivers, reduced by want of rain to slender streams running between extensive mud-banks; and it is possible that, in their anxious efforts to reach the water, they may have only sunk deeper and deeper in the mud until they were engulfed. this idea is strengthened by information supplied to mr. darwin when in these parts (recorded in his _journal_). an eye-witness told him that during the _gran seco_, or great drought, the cattle in herds of thousands rushed into the parana, and, being exhausted by hunger and thirst, were unable to crawl up the muddy banks, and so were drowned. in the last great drought, from to , it is probable (according to calculations made) that the number of animals that died was over one million and a half. the borders of all the lakes and streamlets in the province were long afterwards white with their bones. in the year reports were published of the discovery of large footprints--supposed to be human--in a certain sandstone near carson, nevada, u.s. the locality was the yard of the state prison, and the tracks were uncovered in quarrying stone for building purposes. many different kinds of tracks were found, some of which were made by an animal allied to the elephant; some resembled those of the horse and deer; others seem to have been made by a wolf, and yet others by large birds. those supposed to have been made by human giants were in six series, each with alternate right and left tracks. the stride is from two and a half to over three feet, and each footprint is about eighteen inches long. now, those who believed these tracks to be human must have found it hard to explain how a giant with a foot some eighteen inches long had a stride no longer than that of an ordinary man of to-day, to say nothing of the fact that the straddle was eighteen to nineteen inches! for these and other reasons professor marsh has exploded the idea of their having been made by men, and gave good reasons to show that they were probably made by a giant sloth, such as the mylodon above mentioned, the remains of which have been discovered in the same strata. they agree in size, in stride, and in width between the right and left impressions, very closely with the tracks that a mylodon would have made, and it seems that those of the fore feet were afterwards impressed by the hind feet, so that each track contains two impressions. the reader who has some knowledge of natural history will not need to be told that the sloths of the present day, inhabiting the same region as their gigantic ancestors, are of small size, and live among the branches of the trees, together with the spider monkeys, howlers, and other apes. an interesting question to the evolutionist is--how did the change take place from the old huge and heavy types to the smaller and agile types of the present day? can it be possible that the more difficult and tedious task of pulling down branches and even stems of trees, in order to devour the leaves, was abandoned for the simpler method of climbing up and feeding among the branches? it certainly looks as if a change of this kind had been instituted at some distant period in the past--distant, that is, to _us_, but not very remote geologically. the present method seems so much simpler that we need not be surprised at its adoption, for nature is ever ready to encourage and assist those among the children of life which can hit upon and adopt new and improved methods, either in obtaining food or repelling enemies, or other duties imposed upon them. now, suppose that, in accordance with the well-known fact that variations in the offspring of animals are constantly cropping up, some considerably smaller variety of megatherium, or mylodon, or other now extinct type, appeared on the scene, and, by virtue of its comparative agility, could climb a tree and feed among the branches instead of pulling them down: then, as darwin has so well explained, nature would seize upon this accidental variation, and give it an advantage over its more awkward relations. its offspring, too, would inherit the same characteristics, they would adopt the same habits, and, in time, as "natural selection" further increased these characters, by weeding out those that were unfit while fostering all those that were neither large nor clumsy in climbing trees, a new race of sloths would arise. this new race, it can well be imagined, would in time outstrip the old race in numbers, for successful races multiply while unsuccessful ones diminish. victory is not always to the great and the strong, for cunning and quickness are often of more service than mere brute strength; and perhaps the sloths, as we now see them in the brazilian forests, have hit upon "a new and original plan" by means of which the old colossal forms described above have been driven out of the field, and so exterminated by a process of competition. such an explanation would be in thorough harmony with modern teaching, and, as the other suggestion about long-continued droughts, given on p. , may not appear satisfactory to some of our readers, we offer this theory for what it may be worth. a few words about these modern sloths may not be out of place; for we shall better understand how they have succeeded in the struggle for existence when we know something of their manner of life; and in some ways they still resemble their great ancestors. there are few animals which exhibit in a greater degree what appears to the careless observer to be _deformity_ than the sloth, and none that have, on this account, been more maligned by naturalists. buffon, and many of the older zoologists, were eloquent upon the supposed defects of the unfortunate sloth. these writers gravely asserted that when the sloth ascends a tree, for the purpose of feeding upon its leaves, it is so lazy that it will not quit its station until every trace of verdure is devoured. some of them even went so far as to assert that when the sloth was compelled, after thus stripping a tree, to look out for a fresh supply of food, it would not take the trouble to descend the tree, but just allowed itself to drop from a branch to the ground. even cuvier, who ought to have known better, echoes this tale, and insinuates that nature, becoming weary of perfection, "wished to amuse herself by producing something imperfect and grotesque," when the sloths were formed; and he proceeds, with great gravity, to show the "inconvenience of organisation," which, in his opinion, rendered the sloths unfit for the enjoyment of life. it is quite true that, on the ground, these animals are about the most awkward creatures that can well be imagined. their fore legs are much longer than their hind ones; all their toes are terminated by very long curved claws, and the general structure of the animal is such as to prevent them from walking in the manner of an ordinary quadruped, for they are compelled to rest on the sides of their hands and feet. thus they appear the most helpless of animals, and their only means of progression consists in hooking their claws to some inequality in the ground, and thus dragging their bodies painfully along. but in their natural home, amongst the branches of trees, all these seeming disadvantages vanish--nay, the very peculiarities of structure which render the sloths objects of pity on the ground, are found to render them admirably adapted to their peculiar mode of life. the sloth is a small animal, rarely more than two feet in length, and covered with woolly hair--probably a protection against snakes, its only enemies. it spends nearly the whole of its life in the trees. there, safe from the prowling animals on the ground below, it hangs like a hammock from the bough, and even travels along the branches with its body downwards, using its long claws like grappling-irons. it looks slothful enough when asleep, for then it resembles a bunch of rough hair, and a jumble of limbs close together, hanging to a branch; but when awake it is industrious in its search for nice twigs and leaves, and moves along with considerable activity. when the atmosphere is still, the sloth keeps to its tree, feeding on the leaves and twigs, but when there is wind, and the branches of neighbouring trees come in contact, the opportunity is seized, and the animal moves along the forest under the shady cover of the boughs. the indians have a saying that "when the wind blows the sloth begins to crawl;" and the reason is quite evident, for they cannot jump, but can hang, swing, and crawl suspended. [illustration: plate xix. a gigantic armadillo, glyptodon asper. from buenos ayres. length feet inches.] we now pass on to the old gigantic representative of the armadillo, the glyptodon.[ ] to the eye it resembles more or less an armadillo, and has a huge cuirass, or large plate of armour, covering the whole of the body, but allowing the head to show in front, while the legs come out beneath. both head and tail were also protected with armour. the great shield, or carapace, in most of the extinct armadillos, is composed of long plates of regular shape, closely united at their edges (sutures) so as to form a solid piece. it is evident, therefore, that this creature, having no movable bands, as living armadillos have, could not roll itself up into a ball. the fore feet have thick, short toes, instead of long ones, such as their modern representatives have; and from this we may infer that they were not in the habit of burrowing or of seeking their food underground. the family of glyptodonts seem to have been chiefly confined to the continent of south america, but some species are known to have extended their range as far as mexico, and texas into north america. a good deal of confusion has arisen with regard to the classification of these old-fashioned armadillos, on account of the fact that isolated specimens of their tails have often been found, and these cannot always be referred to the right carapaces. for example, it should be pointed out here that the tail represented in fig. really belongs to another genus, known as hoplophorus.[ ] [ ] so named by sir r. owen, in reference to the sculptured aspect of the grinding surface of the teeth. greek--_glupho_, i carve; _odous, odontos_, tooth. [ ] greek--_hoplon_, armour; _phero_, i bear. in glyptodon asper (plate xix.), the scutes of the carapace had a beautiful rosette-like sculpture, while the sheath of the tail was entirely composed of a series of movable rings, ornamented with large projecting tubercles. the vertebræ of the backbone are almost entirely fused together into a long tube, and also are joined to the under surface of the great shield, to which the ribs are united. the cheek-teeth are sixteen in number, four above and four below on each side. these are channelled with two broad and deep grooves, which divide the surface into three distinct lobes. hence the name of the animal. the tessellated carapace of the glyptodon was at first thought to belong to the megatherium, with which the remains were associated, but professor owen clearly demonstrated the impossibility of this idea. fig. represents glyptodon clavipes (owen) from the pleistocene deposits of buenos ayres; but the reader will gain a much better idea of the animal by inspecting the splendid specimen of glyptodon asper in the natural history museum, near the centre window at the east end of the pavilion (glass-case q on plan). plate xix. is a restoration of another species by our artist.[ ] [ ] this plate is based on a beautiful drawing in a spanish work, _anales del museo publico buenos aires_. g. burmeister, m.d., phil. d. tomo segundo. in the museum of the royal college of surgeons (which the reader is recommended to visit) there are several most valuable specimens of these extinct armadillos from south america. [illustration: fig. .--extinct gigantic armadillo, _glyptodon clavipes_, from pleistocene deposits, buenos ayres. (the tail sheath here represented probably belongs to another genus, hoplophorus.)] armadillos belong, with sloths and ant-eaters, to the same family of so-called toothless animals (edentata) with no front teeth, though one or two forms really are toothless. those of the present day have their bony armour divided up into a series of bands, so that they can roll themselves up, more or less, into balls. they burrow under the ground, where they get their food to a certain extent, and live a safe life, protected by their casque of mail. their only enemies seem to be the monkeys, and one of the tricks of the young monkeys in the american forests is, when they find an armadillo away from home, to pull its tail unmercifully, and try to drag it about. snakes cannot hurt them. mr. hudson, in his most interesting book, _a naturalist in la plata_, narrates how he watched an armadillo kill a snake and then devour it. if we examine the anatomy of the armadillo, we shall find that its bones greatly resemble those of the sloth, but still there are a few differences. it is a burrowing animal, and therefore requires great power of scratching and tearing the ground. why the colossal forms of armadillo should have become extinct and only small ones survived to the present time, is one of the many and perplexing problems presented by the study of extinct animals. one would have thought from its size and strength that the glyptodon had been built, like rome, for eternity. chapter xiii. the mammoth. "yes, where the huntsman winds his matin horn, and the couched hare beneath the covert trembles; where shepherds tend their flocks, and grow their corn where fashion in our gay parade assembles-- wild horses, deer, and elephants have strayed, treading beneath their feet old ocean's races." horace smith. many are the traditions and tales that have clustered round the mammoth.[ ] he is, however, no fabulous product of the imagination, like the dragon, for he has actually been seen in the flesh, and not only _seen_, but eaten, both by men and animals! but, for all that, men's minds have been busy for centuries past making up tales, often of the wildest description, about him; and it is little wonder that a creature whose bones are found in the soils and gravels, etc., over more than half the world, and whose body has been seen frozen in siberian ice, should have given rise to many tales and superstitions. to students of folk-lore these legends are of considerable interest, and to some extent also to men of science. to the latter, however, one of its many points of interest is that palæontology may be said to have been founded on the mammoth. cuvier, the illustrious founder of the science of organic remains, was enabled, by his accurate and minute knowledge of the structures of living animals, to prove to his astonished contemporaries that the mammoth bones and teeth, so plentifully discovered in europe, were not such as could have belonged to any living elephant, and consequently that there must have existed, at some previous period in the world's history, an elephant of a different kind, and quite unknown to naturalists. this was a new idea, and accordingly one that met with opposition as well as incredulity. [ ] the word _mammoth_ is thought by pallas and nordenskiöld to be of tartar origin. the former asserts that the name originated in the word _mamma_, which signifies earth (the mammoth being found frozen in the earth). it was introduced into the languages of western europe about two centuries ago, from the russian. but other writers have attempted to prove that it is a corruption of the arabic word _behemoth_, or "great beast," which in the book of job signifies an unknown animal. in an ancient chinese work, of the fifth century before christ, it is spoken of under the name _tien-schu_, that is to say, "the mouse which hides itself." the chinese legends are referred to on p. . it was thought in those days that whatever animals lived in the past _must_ have resembled those now inhabiting the world, and the idea of extinct types unknown to man, and unknown to the regions where their bones were found embedded below the soil, was of so novel and startling a character as to appear incredible. besides, the mosaic account of creation made no direct reference to extinct animals, and therefore the notion was not to be entertained. it is amusing to note the devices to which people resorted in order to combat this revolutionary teaching. thus, when cuvier first announced the discovery of the fossil remains of the elephant, hippopotamus, and rhinoceros in the superficial deposits of continental europe, he was gravely reminded of the elephants introduced into italy by pyrrhus in the roman wars, and afterwards in the roman triumphal processions or the games at the colosseum. it was only by means of minute anatomical differences that he was able to show that the bones and teeth of these elephants must have belonged to a species unlike those now living. but these differences proved too subtle for even scientific men to appreciate, so slight was their knowledge of anatomy compared with his; so that they were either disallowed or explained away. but he was not to be beaten, and appealed to the fact that similar remains occurred in great britain, whither neither romans nor others could have introduced such animals. these are his words: "if, passing across the german ocean, we transport ourselves into britain, which in ancient history by its position could not have received many living elephants besides that one which cæsar brought thither, according to polycenus; we shall, nevertheless, find these fossils in as great abundance as on the continent." another crushing answer to the absurd explanations of cuvier's countrymen was added by the sagacious dean buckland, who pointed out that in england, as on the continent, the remains of elephants are accompanied by the bones of the rhinoceros and hippopotamus, animals which not even roman armies could have subdued or tamed! owen also adds that the bones of fossil elephants are found in ireland, where cæsar's army never set foot. it was in that cuvier announced that the teeth and bones of the european fossil elephants were distinct in species from both the african and the indian elephant, the only two living species (el. africanus and el. indicus). this fundamental fact opened out to him new views about the creation of the world and its inhabitants, and a rapid glance over other fossil bones in his collection showed him the truth and the value of this great idea (namely, the existence of extinct types), to which he consecrated the rest of his life. thus palæontology may be said to have been founded on the mammoth. the fossil remains of elephants have, on account of their common occurrence in various parts of the world, attracted a great deal of attention, both from the learned and the unlearned. in the north of europe they have been found in ireland, in germany; in central europe, in poland, middle and south russia, greece, spain, italy; also in africa, and over a large part of asia. in the new world they have been found abundantly in north america. but in the frozen regions of siberia its tusks, teeth, and bones are met with in very great abundance. according to pallas, the great russian savant, there is not in the whole of asiatic russia, from the don to the extremity of the tchutchian promontory, any brook or river on the banks of which some bones of elephants and other animals foreign to these regions have not been found. the primæval elephants (mammoth, mastodon, etc.) appear to have formerly ranged over the whole northern hemisphere of the globe, from the fortieth parallel to the sixtieth, and possibly to near the seventieth degree of latitude. just as the north american indian regards the great bones of professor marsh's extinct eocene mammals that peep out from the sides of buttes and cañons, as belonging to his ancestors, so we find that in all parts of the world the bones of extinct elephants have, on account of their great size (and partly from a certain resemblance, in some, to bones of the human skeleton), been regarded as testifying to the former existence of giants, heroes, and demigods. to the present day the hindoos consider such remains as belonging to the _rakshas_, or titans,--beings that figure largely in their ancient writings. theophrastus, of lesbos, a pupil of aristotle, appears to have been the first to record the discovery of fossil ivory and bones. these were probably obtained by the country people from certain deposits in the neighbourhood, and are mentioned five hundred years later by pausanias. several greek legends and traditions appear to be founded on such discoveries. thus the greeks mistook the knee-bone of an elephant for that of ajax. in like manner the supposed body of orestes, thirteen feet in length, discovered by the spartans at tegea, doubtless was the skeleton of some elephant. in the isle of rhodes, in sicily, and near palmero, syracuse, and at many other places, similar remains have afforded a basis for stories of giants. in fact, so much has been said by old writers on this subject, that whole volumes might be filled with such matter. let one or two examples suffice. in the year some workmen in a sand-pit near the castle of chaumont, not far from st. antoine, found some bones (probably of the mammoth or mastodon) of the nature of which they were entirely ignorant, and many of them they broke up. but a certain surgeon named mazuyer, hearing of the discovery, bought the bones, and announced that he had himself discovered them in a tomb thirty feet long, bearing in gothic characters the inscription, "teutobochus rex." this was a barbarian king who invaded gaul at the head of the cimbri, and was defeated near aix, in provence, by marius, who brought him to rome to grace his triumphal procession. mazuyer reminded his credulous readers that, according to the testimony of roman authors, the head of this king was larger than any of the trophies borne upon the lances in triumph, and for a time his marvellous story was accepted. the skeleton of this pretended giant-king was exhibited in many cities of france and germany, and also before louis xii., who took great interest in it. the imposture was detected and exposed by riolan, and thus a great controversy arose, and numerous pamphlets were written on both sides. the skeleton remained at bordeaux till the year , when it was sent to the museum of natural history at paris, where it may still be seen. it is needless to say that, on its arrival there, m. blainville at once recognised it as being that of an elephant--a mastodon, in fact. another giant-story may be narrated as follows. in the year some large bones were discovered, through the uprooting of an oak by a storm, in the canton of lucerne, in switzerland. these bones were afterwards declared by the celebrated physician and professor at basle, felix plater, to be those of a giant. this learned man estimated the height of the giant at nineteen feet! and made a drawing thereof, which he sent to lucerne. the bones have since nearly all vanished, but blumenbach, at the beginning of this century, saw enough of them to prove their elephantine nature. the good people of lucerne, however, being reluctant to abandon their giant, have, since the sixteenth century, made him the supporter of their city arms. the church of st. christopher, at valence, possessed an elephant's tooth, which was shown as the tooth of st. christopher. as this relic was "bigger than a man's fist," it is difficult to picture what idea the people entertained of their saint! in two peasants observed on the banks of the rhone, along a slope, some great bones sticking out of the ground. these they carried to the neighbouring village, where they were examined by cassanion, who lived at valence, and was the author of a treatise on giants (_de gigantibus_). cuvier concluded from this writer's description of the tooth that it belonged to an elephant. otto de guericke, famous as the inventor of the air-pump, in witnessed the discovery of a fossil elephant, with its tusks preserved. these he mistook for horns; so did even the illustrious leibnitz, who created out of his own imagination a strange animal, with a great horn in the middle of its forehead, as the creature to which these remains belonged! one is reminded of bret harte's amusing _jeu d'esprit, the society upon the stanislaus_-- "then brown he read a paper, and he reconstructed there, from those same bones, an animal that was extremely rare;" and how the members of this learned society came to blows over their fossil bones, and hurled them at one another--"till the skull of an old mammoth caved the head of thomson in." but in this case, the "animal that was extremely rare" was believed in for a long time, and leibnitz's "fossil unicorn" was universally accepted throughout germany for more than thirty years. at last, however, a complete skeleton of a mammoth was discovered, and recognised as belonging to an elephant; but the unicorn was not given up without a keen controversy.[ ] [ ] the writer is indebted for much of the information here given with regard to the discoveries of mammoth bones, and legends founded thereon, to m. figuier's _world before the deluge_. near the city of constadt, in the year , a great quantity of bones and tusks of elephants were discovered, after excavations had been made by order of the reigning duke, who had been informed by a soldier of würtemberg of the presence of bones in the soil. in this way some sixty tusks were unearthed. the whole ones were preserved, but those which were broken were given to the court physician, who made use of them for medicinal purposes. after this the "ebur fossile," or "unicornu fossile," was freely used by the german doctors, until the discovery of the bone-caves of the hartz, when it became too abundant to pass for true unicorn, and consequently lost much of its repute. in our own country elephantine remains have also given rise to strange tales. the village of walton, near harwich, is famous for the abundance of mammoth remains, which lie along the base of the sea-cliffs, mixed with the bones of horses, oxen, and deer. "the more bulky of these fossils," says professor owen, "appear to have early attracted the notice of the curious. lambard, in his _dictionary_, says that 'in queen elizabeth's time bones were found, at walton, of a man whose skull would contain five pecks, and one of his teeth as big as a man's fist, and weighed ten ounces. these bones had sometimes bodies, not of beasts, but of men, for the difference is manifest.'" according to the same authority, there is reason to believe that instances have occurred in great britain in which, with due care and attention, a more or less entire skeleton of the mammoth might have been secured. he mentions the case of the discovery of a number of mammoth bones by some workmen in a brick-ground, near the village of grays, in essex. but most unfortunately, in their ignorance, they broke up these valuable relics, and sold the fragments, for three half-pence a pound, to a dealer in old bones! this somewhat lucrative traffic went on for over half a year before the matter came to the notice of mr. r. ball, f.g.s., who recovered some fine bones from the men, and thus rescued them from the destruction that awaited them. it is greatly to be hoped that some day our national treasure house at south kensington may be enriched with a complete mammoth skeleton from british soil. the chinese, as might be expected, heard of the mammoth long before europeans did, and they have some strange stories about it. in the northern part of siberia, so great is the abundance of mammoth tusks, that for a very long period there has been a regular export of mammoth ivory, both eastward to china and westward to europe. even in the middle of the tenth century an active trade was carried on at khiva in fossil ivory, which was fashioned into combs, vases, and other objects, as related by an arab writer of that time. middendorf reckoned that the number of fossil tusks which have yearly come into the market, during the last two centuries, has been at least a hundred pairs--an estimate which nordenskiöld considers as well within the mark. they are found all along the line of the shore between the mouth of the obi and behring straits, and the further north a traveller goes, the more numerous does he find them. the soil of bear island and of the liachoff islands (new siberia) is said to consist only of sand and ice with such quantities of mammoth bones that it appears as if they were almost made up of bones and tusks. every summer numbers of fishermen make for these islands to collect fossil ivory, and during the winter immense caravans return laden with mammoth tusks. the convoys are drawn by dogs, and in this way the ivory reaches both the ancient eastern and the newer western markets. it is evident from the chinese legends that the frozen bodies of mammoths have for ages past been either seen by, or reported to, members of the celestial empire, for it is mentioned in some of their old books as an animal that lives underground. in a great chinese work on natural history, written in the sixteenth century, the following quaint description occurs: "the animal named _tien-schu_, of which we have already spoken, in the ancient work upon the ceremonial entitled _lyki_ [a work of the fifth century before christ] is called also _fyn-schu_, or _yn-schu_, that is to say, 'the mouse that hides itself.' it always lives in subterranean caverns; it resembles a mouse, but is of the size of a buffalo or ox. it has no tail; its colour is dark; it is very strong, and excavates caverns in places full of rocks and forests." another writer says, "the _fyn-schu_ haunts obscure and unfrequented places. it dies as soon as it is exposed to the rays of the sun or moon; its feet are short in proportion to its size, which causes it to walk badly. its tail is a chinese ell in length. its eyes are small, and its neck short. it is very stupid and sluggish. when the inundations of the river _tamschuann-tuy_ took place [in ] a great many _fyn-schu_ appeared in the plain; it fed on the roots of the plant _fu-kia_." an old russian traveller, who, in , was sent by peter the great as ambassador to the emperor of china, mentions the discovery of the heads and legs of mammoths in frozen soil. after referring to these discoveries, he says, "concerning this animal there are very different reports. the heathens of jakutsk, tungus, and ostiaks say that they continually, or at least, by reason of the very hard frosts, mostly live underground, where they go backwards and forwards; to confirm which they tell us that they have often seen the earth heaved up when one of these beasts was upon the march, and, after he passed, the place sink in, and thereby make a deep pit. they further believe that if this animal comes so near to the surface of the frozen earth as to smell the air, he immediately dies, which they say is the reason that several of them are found dead on the high banks of the river, where they unawares came out of the ground. this is the opinion of the infidels concerning these beasts, which are never seen. but the old siberian russians affirm that the mammoth is very like the elephant, with this difference only, that the teeth of the former are firmer, and not so straight as those of the latter.... by all i could gather from the heathens, no person ever saw one of these beasts alive, or can give any account of its shape; so that all we heard said on this subject arises from bare conjecture only." but making all allowance for the gross absurdities of these accounts, it is clear that they are based on descriptions--probably by the tungusian fishermen--of carcases that have been washed out of the frozen soil by rivers in flood time. now that we are in possession of trustworthy accounts, we can understand how these strange tales arose among an ignorant and superstitious people, such as the fishermen of these inhospitable shores. we will now put before the reader the true accounts given by adams[ ] and benkendorf. [ ] abridged from _memoirs of the imperial academy of sciences of st. petersburg_, vol. v. london, . in a tungusian, named schumachoff, who generally went to hunt and fish at the peninsula of tamut after the fishing season of the lena was over, had constructed for his wife some cabins on the banks of the lake oncoul, and had embarked to seek along the coasts for mammoth tusks. one day he saw among the blocks of ice a shapeless mass, but did not then discover what it was. in he perceived that this object was more disengaged from the ice, and that it had two projecting parts; and towards the end of the summer of the entire side of the animal and one of his tusks were quite free from ice. in the enormous mass fell by its own weight on a bank of sand. it was a frozen mammoth! in schumachoff came to his mammoth, and having cut off the tusks, exchanged them with a merchant for goods. two years afterwards mr. adams, the narrator of the story, traversed these distant and desert regions, and found the mammoth still in the same place, but sadly mutilated. the people of the neighbourhood had cut off the flesh, and fed their dogs with it during the scarcity. wild beasts, such as white bears, wolves, and foxes, also had fed on it, and the traces of their footsteps were seen around. the skeleton was complete all except one leg, but the flesh had almost all gone. the head was covered with a dry skin, one of the ears was seen to be covered with a tuft of hairs. all these parts suffered more or less injury in transport for a distance of miles to st. petersburg, yet the eyes have been preserved. this mammoth was a male, with a long mane on its neck, but both tail and proboscis had disappeared. the skin is of a dark grey colour, covered with a reddish wool and black hairs. the entire carcase was nine feet four inches high. the skin of the side on which the carcase had lain was detached by mr. adams, for it was well preserved, but so heavy was it that ten persons found great difficulty in transporting it to the shore. the white bears, while devouring the flesh, had trodden into the ground much of the hair belonging to the carcase, but mr. adams was able by digging to procure about sixty pounds' weight of hair. in a few days the work was completed, and he found himself in possession of a treasure which amply compensated him for the fatigues and dangers of the journey as well as the expense of the enterprise. when first seen, this mammoth was embedded in clear pure ice, which forms in that coast escarpments of considerable thickness, sloping towards the sea, the top of which is covered with moss and earth. if the account of the tungusians can be trusted, the carcase was some way below the surface of the ice when first seen. arrived at takutsk, mr. adams purchased a pair of tusks which he believed to belong to this mammoth, but there is reason to doubt whether he did get the right tusks. they are nine feet six inches long. [illustration: fig. .--skeleton of mammoth, _elephas primigenius_ (partly restored), in the museum at brussels. drawn from a photograph, by j. smit.] the skeleton of this specimen, the fame of which may be said to have spread all over the world, is now set up in the museum of the st. petersburg academy, and the skin still remains attached to the head and feet. a part of the skin and some of the hair were sent by mr. adams to sir joseph banks, who presented them to the museum of the royal college of surgeons.[ ] a photograph of the skeleton as it now stands, may be seen on the wall of the big geological gallery at south kensington (no. i. on plan), near the specimens of mammoth tusks. but it should be pointed out that _the tusks are put on the wrong way_; for they curve outwards instead of inwards, thus presenting a somewhat grotesque appearance. for this reason we have not reproduced the familiar woodcut based on an engraving in the memoir already referred to.[ ] but we give, instead, a sketch taken from a photograph (also on the wall in gallery no. i.) of a fine skeleton in the brussels museum (fig. ). here the tusks are seen correctly inserted. we must also draw the reader's attention to the remarkably fine specimen (glazed case e on plan) consisting of the skull and both tusks complete, found at ilford in essex. [ ] a specimen of the hair of a mammoth may be also seen at the natural history museum (pier case ) in a tall glass jar. it came from frozen soil, behring strait. by the side of this will be seen, in a glass box, a portion of the skin of a mammoth, from the banks of the river alaseja, province of yakutsk, siberia. it exhibits the under fur, the long hair having entirely disappeared. [ ] fig. in part i. of the _guide to the exhibition galleries in the department of geology and palæontology in the british museum (natural history), cromwell road_. (price _s._) this most useful guide should be consulted by the reader. adams's specimen was, dr. woodward thinks, an old individual, and its tusks had curved upwards so much as to be of little use. in younger ones they were less curved. the hair that still remains on the skin of the st. petersburg specimen is of the colour of the camel, very thick-set and curled in locks. bristles of a dark colour are interspersed, some reddish, and some nearly black. the colour of the skin is a dull black, as in living elephants (see restoration, plate xx.). remains of the mammoth (elephas primigenius) have been found in great numbers in the british isles. a list of localities (from mr. leith adams's monograph on fossil elephants) is given in the appendix, but even this might be extended. mr. samuel woodward calculated that upward of two thousand grinders of elephants have been dredged up during a period of thirteen years upon the oyster-bed off hasborough, on the norfolk coast. but many of these doubtless belong to other species of older date, such as elephas antiquus. dr. bree, of colchester, says that the sea-bottom off dunkirk, whence he has made a collection, is so full of mammalian remains that the sailors speak of it as "the burying-ground." the remains of the mammoth occur over a very large geographical area--fully half the globe. by far the most important discovery of a frozen mammoth is that of a young russian engineer, benkendorf by name, who was an eye-witness of its resurrection, though, most unfortunately, he was unable either to procure his specimen, as mr. adams did, or to make drawings of it. being employed by the russian government in making a survey of the coast off the mouth of the lena and indigirka rivers, he was despatched up the latter river in , in command of a small steam-cutter. the following is a translation of the account which he wrote to a friend in germany. [illustration: plate xx. the mammoth, elephas primigenius. an inhabitant of northern regions during the great ice age.] "in there was unusually warm weather in the north of siberia. already in may unusual rains poured over the moors and bogs, storms shook the earth, and the streams carried not only ice to the sea, but also large tracts of land, thawed by the masses of warm water fed by the southern rains.... we steamed on the first favourable day up the indigirka; but there were no thoughts of land; we saw around us only a sea of dirty brown water, and knew the river only by the rushing and roaring of the stream. the river rolled against us trees, moss, and large masses of peat, so that it was only with great trouble and danger that we could proceed. at the end of the second day, we were only about forty versts up the stream; some one had to stand with the sounding-rod in hand continually, and the boat received so many shocks that it shuddered to the keel. a wooden vessel would have been smashed. around us we saw nothing but the flooded land for eight days. we met with the like hindrances until at last we reached the place where our jakuti were to have met us. further up was a place called ujandina, whence the people were to have come to us; but they were not there, prevented evidently by the floods. "as we had been there in former years, we knew the place. but how it had changed! the indigirka, here about three versts wide, had torn up the land and worn itself a fresh channel; and when the waters sank we saw, to our astonishment, that the old river-bed had become merely that of an insignificant stream. this allowed me to cut through the soft earth, and we went reconnoitring up the new stream, which had worn its way westwards. afterwards we landed on the new shore, and surveyed the undermining and destructive operation of the wild waters, that carried away, with extraordinary rapidity, masses of soft peat and loam. it was then that we made a wonderful discovery. the land on which we were treading was moorland, covered thickly with young plants. many lovely flowers rejoiced the eye in the warm beams of the sun, that shone for twenty-two out of the twenty-four hours. the stream rolled over and tore up the soft wet ground like chaff, so that it was dangerous to go near the brink. while we were all quiet, we suddenly heard under our feet a sudden gurgling and stirring, which betrayed the working of the disturbed waters. suddenly our jäger, ever on the outlook, called loudly, and pointed to a singular and unshapely object, which rose and sank through the disturbed waters. i had already remarked it, but not given it any attention, considering it only drift-wood. now we all hastened to the spot on the shore, had the boat drawn near, and waited until the mysterious thing should again show itself. our patience was tried, but at last a black, horrible, giant-like mass was thrust out of the water, and we beheld a colossal elephant's head, armed with mighty tusks, with its long trunk moving in the water in an unearthly manner, as though seeking for something lost therein. breathless with astonishment, i beheld the monster hardly twelve feet from me, with his half-open eyes yet showing the whites. it was still in good preservation. "'a mammoth! a mammoth!' broke out the tschernomori; and i shouted, 'here, quickly. chains and ropes!' i will go over our preparations for securing the giant animal, whose body the water was trying to tear from us. as the animal again sank, we waited for an opportunity to throw the ropes over his neck. this was only accomplished after many efforts. for the rest we had no cause for anxiety, for after examining the ground i satisfied myself that the hind legs of the mammoth still stuck in the earth, and that the waters would work for us to unloosen them. we therefore fastened a rope round his neck, threw a chain round his tusks, that were eight feet long, drove a stake into the ground about twenty feet from the shore, and made chain and rope fast to it. the day went by quicker than i thought for, but still the time seemed long before the animal was secured, as it was only after the lapse of twenty-four hours that the waters had loosened it. but the position of the animal was interesting to me; it was standing in the earth, and not lying on its side or back as a dead animal naturally would, indicating by this the manner of its destruction. the soft peat or marsh land, on which he stepped thousands of years ago, gave way under the weight of the giant, and he sank as he stood on it, feet foremost, incapable of saving himself; and a severe frost came and turned him into ice, and the moor which had buried him. the latter, however, grew and flourished, every summer renewing itself. possibly the neighbouring stream had heaped over the dead body plants and sand. god only knows what causes had worked for its preservation; now, however, the stream had brought it once more to light of day, and i, an ephemera of life compared with this primæval giant, was sent by heaven just at the right time to welcome him. you can imagine how i jumped for joy. "during our evening meal, our posts announced strangers--a troop of jakuti came on their fast, shaggy horses. they were our appointed people, and were very joyful at the sight of us. our company was augmented by them to about fifty persons. on showing them our wonderful capture, they hastened to the stream, and it was amusing to hear how they chattered and talked over the sight. the first day i left them in quiet possession, but when, on the following, the ropes and chains gave a great jerk, a sign that the mammoth was quite freed from the earth, i commanded them to use their utmost strength and bring the beast to land. at length, after much hard work, in which the horses were extremely useful, the animal was brought to land, and we were able to roll the body about twelve feet from the shore. the decomposing effect of the warm air filled us all with astonishment. "picture to yourself an elephant with a body covered with thick fur, about thirteen feet in height, and fifteen in length, with tusks eight feet long, thick, and curving outward at their ends,[ ] a stout trunk of six feet in length, colossal limbs of one and a half feet in thickness, and a tail, naked up to the end, which was covered with thick tufty hair. the animal was fat and well-grown; death had overtaken him in the fulness of his powers. his parchment-like, large, naked ears, lay fearfully turned over the head; about the shoulders and the back he had stiff hair, about a foot in length, like a mane. the long outer hair was deep brown and coarsely rooted. the top of the head looked so wild, and so penetrated with pich[ ] that it resembled the rind of an old oak tree. on the sides it was cleaner, and under the outer hair there appeared everywhere a wool, very soft, warm and thick, and of a fallow-brown colour. the giant was well protected against the cold. the whole appearance of the animal was fearfully strange and wild. it had not the shape of our present elephants. as compared with our indian elephants, its head was rough, the brain-case low and narrow, but the trunk and mouth were much larger. the teeth were very powerful. our elephant is an awkward animal, but compared with this mammoth it is as an arabian steed to a coarse, ugly dray-horse. i could not divest myself of a feeling of fear as i approached the head; the broken, widely-open eyes, gave the animal an appearance of life, as though it might move in a moment and destroy us with a roar.... the bad smell of the body warned us that it was time to save of it what we could, and the swelling flood, too, bid us hasten. first of all we cut off the tusks, and sent them to the cutter. then the people tried to hew off the head, but notwithstanding their good will, this work was slow. as the belly of the animal was cut open the intestines rolled out, and then the smell was so dreadful that i could not overcome my nauseousness, and was obliged to turn away. but i had the stomach separated, and brought on one side. it was well filled, and the contents instructive and well preserved. the principal were young shoots of the fir and pine; a quantity of young fir-cones, also in a chewed state, were mixed with the mass.... as we were eviscerating the animal, i was as careless and forgetful as my jakuti, who did not notice that the ground was sinking under their feet, until a fearful scream warned me of their misfortune, as i was still groping in the animal's stomach. shocked, i sprang up, and beheld how the river was burying in its waves our five jakuti and our laboriously saved beast. fortunately, the boat was near, so that our poor workpeople were all saved, but the mammoth was swallowed up by the waves, and never more made its appearance." [ ] this must be incorrect (see p. ). [ ] "und mit pech so durchgedrungen." much may be learned from this highly interesting account; it contains the key to several questions which otherwise might have remained unsolved. let us see what conclusions can be derived therefrom. _first_, its position and perfect state of preservation are sufficient to prove that it was buried where it died. it sank in a marsh, probably during the summer. then came the cold of winter; the carcase, together with the ground around it, was frozen so that decomposition was arrested, and frozen it must have remained for many centuries till the day when m. benkendorf came across it. or it may have been buried up in a snow-drift which in time became ice. in the region where frozen mammoths occur (and there are at least nine cases on record), a considerable thickness of frozen soil may be found at all seasons of the year; so that if a carcase be once embedded in mud or ice, its putrefaction may be arrested for indefinite ages. according to one authority, the ground is now permanently frozen even to the depth of four hundred feet at the town of jakutsh, on the western bank of the river lena. throughout a large part of siberia the boundary cliffs of the lakes and rivers consist of earthy materials and ice in horizontal layers. middendorf bored to the depth of seventy feet, and after passing through much frozen soil mixed with ice, came down upon a solid mass of pure transparent ice, the depth of which he was unable to ascertain. the year , when m. benkendorf saw his mammoth, was exceptional on account of its unusually warm summer, so that the ground of the tundra region thawed, and was converted into a morass. had any mammoths been alive then, and strayed beyond the limits of the woods into the tundra, probably some of them would have been likewise engulphed, and, when once covered up and protected from the decaying action of the air, the cold of the next winter would have frozen their carcases as this one must have been frozen up. truly, "there is nothing new under the sun," and the present highly useful method of freezing meat and bringing it over from america or new zealand to add to our insufficient home supplies, is but a resort to a process employed by nature long before the age of steamships, and perhaps even before the appearance of man on the earth! _secondly_, with regard to the food of the mammoth, benkendorf's discovery is of great service in solving the question how such a creature could have maintained its existence in so inhospitable and unpromising a country. the presence of fir-spikes in the stomach is sufficient to prove that it fed on vegetation such as is now found at the northern part of the woods as they join the low treeless tundra in which the body lay buried. before this discovery the food of the mammoth was unknown, and all sorts of theories were devised in order to account for its remains being found so far north. some thought that the mammoth lived in temperate regions, and that the carcases were swept down by great floods into higher and colder latitudes. but it would be impossible for the bodies to be hurried along a devious course for so many miles without a good deal of injury, and probably they would fall to pieces on the way. but, as professor owen has so convincingly argued, there is no reason why herds of mammoths should not have obtained a sufficient supply of food in a country like the southern part of siberia, where trees abound in spite of the fact that during a great part of the year it is covered with snow. and this is his line of reasoning. the molar teeth of the elephant show a highly complicated and peculiar structure, and there are no other quadrupeds that feed to such an extent on the woody fibre of the branches of trees. many mammals, as we know, eat the leaves of trees; some gnaw the bark; but elephants alone tear down and crunch the branches. one would think there was but little nourishment to be got from such. but the hard vertical plates of their huge grinders enable them to pound up the tough vegetable tissue and render it more or less palatable. of course, the foliage is the most tempting, but where foliage is scarce something more is required. now, in the teeth of the mammoth the same principle of construction is observed, only with greater complexity, for there are more of these grinding plates and a larger proportion of dense enamel. hence the inference seems unmistakable that the extinct species fed more largely on woody fibre than does the elephant of to-day. forests of hardy trees and shrubs still grow upon the frozen soil of siberia, and skirt the banks of the lena as far north as the sixtieth parallel of latitude. if the mammoth flourished in temperate latitudes only, as formerly suggested, then its thick shaggy coat becomes superfluous and meaningless; but if it lived in the region where its body has been found, then the argument from its teeth, and the fir-spikes found in its stomach, is confirmed by the nature of its skin, and all the old difficulties vanish. professor owen considers that we may safely infer that, if living at the present day, it would find a sufficient supply of food at all seasons of the year in the sixtieth parallel, and even higher. perhaps they migrated north during the summer; and, judging from the present limits of arboreal vegetation, they may have been able to subsist even in latitude ° north, for at the extreme points of lapland pines attain a height of sixty feet.[ ] [ ] sir henry howorth, in his _mammoth and the flood_, suggests another theory, and gives some valuable information. it is often no easy matter to form conclusions with regard to the habits of extinct animals; and too much reliance must not be placed on arguments derived from the habits of their living descendants or their near relations. the older geologists fell into this mistake with regard to the mammoth, as did even cuvier. modern elephants are at present restricted to regions where trees flourish with perennial foliage, and, therefore, it was argued that there must have been a change of climate--either gradual or sudden, in the country of the mammoth. cuvier, who believed in sudden revolutions on the earth's surface, argued that the mammoth could not possibly have lived in siberia as it is now; and that, at the very moment when the beast was destroyed, the land was suddenly converted into a glacial region! ("c'est donc le même instant qui a fait périr les animaux, et qui a rendu glacial le pays qu'ils habitaient, cet événement a été subit, instantané, sans aucune gradation."[ ]) sir charles lyell argued, from geological evidence with regard to the rise of land along the siberian coast, that the climate had become somewhat more severe, and that finally the mammoth, though protected by its shaggy coat, died out on account of scarcity of food.[ ] [ ] _ossemens fossiles_, tom. i. p. . [ ] see _the principles of geology_, vol. i. chap. x. professor owen is unwilling to believe that such changes as these brought about the final extinction of the mammoth, and he concludes that it was quite possible for such an animal to have flourished as near to the north pole as is compatible with the growth of hardy trees or shrubs. "the fact seems to have been generally overlooked, that an animal organised to gain its subsistence from the branches or woody fibre of trees, is thereby rendered independent of the seasons which regulate the development of leaves and fruit; the forest food of such a species becomes as perennial as the lichens that flourish beneath the winter snows of lapland; and, were such a quadruped to be clothed, like the reindeer, with a natural garment capable of resisting the rigours of an arctic winter, its adaptation for such a climate would be complete.... the wonderful and unlooked-for discovery of an entire mammoth, demonstrating the arctic character of its natural clothing, has, however, confirmed the deductions which might have been legitimately founded upon the localities of its most abundant remains, as well as upon the structure of its teeth, viz. that, like the reindeer and musk ox of the present day, it was capable of existing in high northern latitudes."[ ] [ ] _a history of british fossil mammals and birds_, by richard owen, f.r.s., etc. london, . the problem of the extinction of the mammoth is not an easy one to solve. we can hardly account for its disappearance by calling in geographical changes by which its range became restricted, and its food supply diminished, so that in the competition with other herbivorous animals this primæval giant "went to the wall," as the saying is. nor does lyell's appeal to a change in climate, by which the cold of siberia became too intense even for the mammoth, seem quite satisfactory, especially when we remember how very far north fir trees range (p. ). the mammoth, probably, was endowed with a fairly tough constitution. in siberia it fed on fir trees. in kentucky it fared better, and was surrounded by such vegetation as now flourishes in that temperate region. in the valley of the tiber (where also its remains are found), though during the "glacial period" the temperature was, doubtless, lower than at present, we cannot imagine that an arctic climate prevailed. thus we see that it was capable of flourishing in various and widely separated regions where the conditions of climate and food supply could hardly have been similar. professor boyd dawkins, whose views we are adopting here,[ ] considers that the mammoth was exterminated by man--a simple solution of the question, which seems to present no difficulties. that it was hunted by the primitive folk of the "reindeer period" in france, is proved by its remains in the caves where men dwelt, and by a drawing cut by a hunter of the older stone age on one of its own tusks! a cast of this most interesting relic may be seen in the prehistoric collection at the british museum, and shows that the men of that time were not devoid of artistic power (see fig. ). some of the lines in this illustration represent cracks in the original, so that the actual outline is not easily made out. but here we see the head particularly well drawn, the tusks and downward lines indicating the hairy mane. reindeer and other animals were also engraved on horn, etc., by the men who were contemporary with the mammoth. [ ] _popular science review_, vol. vii. p. ( ). [illustration: fig. .--figure of the mammoth, engraved on mammoth ivory by cavemen, la madelaine, france. in the lartet collection, paris.] we know that man has exterminated a great many noble animals in his time, and, alas! continues to do so at the present time in africa, and in north and south america. the giraffe and the bison, once so plentiful, are now almost extinct. primitive man was a hunter, and, as he multiplied, his wants became greater, and more animals were therefore destroyed. probably the same explanation applies to the great moa bird of new zealand, and possibly even to the megatherium of south america. with regard to the tusks of the mammoth, which are considerably larger than those of either the african or indian elephant, it is evident that they must have been of some service, for nature would never have endowed the animal with such great and ponderous instruments--to support which the skull is greatly modified in both the mammoth and elephant--without some definite purpose. we have often been asked how the mammoth used his tusks; now, this question can best be answered by reference to the habits of living elephants. the elephant of to-day is a fairly peaceable creature, but, if attacked, can despatch the aggressor in various ways. some enemies he can crush under his feet; a man he can pick up with his trunk and hurl to a considerable distance, probably with fatal results. but the tusks do not appear to be used as weapons of offence or defence. we must consider how the animal feeds. the general food of the elephant consists of the foliage of trees. in africa it feeds largely on mimosas. now, it is clear that, in spite of having a long trunk, an elephant cannot obtain all the leaves of a tall tree while the tree remains standing; mimosa trees, for instance, are often thirty feet high, and have richer foliage at the crown. so it appears that they actually overturn them. on this point we have the testimony of sir samuel baker, who says, "the destruction caused by a herd of elephants in a mimosa forest is extraordinary, and i have seen trees uprooted of so large a size that i am convinced no single elephant could have overturned them. i have measured trees four feet six inches in circumference, and about thirty feet high, uprooted by elephants. the natives assured me that the elephants mutually assist each other, and that several engage together in the work of overturning a large tree. none of the mimosas have tap-roots; thus the powerful tusks of the elephants applied as crowbars at the roots, while others pull at the branches with their trunks, will effect the destruction of a tree so large as to appear invulnerable." another writer says the elephant also feeds on a variety of bulbs, the situation of which is indicated by his exquisite sense of smell, and that, to obtain these, he turns up the ground with his tusks, so that whole acres may be seen thus ploughed up. now, in siberia, where the ground would be harder, we can imagine that the larger tusks of the mammoth would be highly serviceable in uprooting fir trees and breaking off their branches, for benkendorf's fortunate discovery informs us that such trees formed at least part of their food. chapter xiv. the mastodon and the woolly rhinoceros. "of one departed world i see the mighty show." another elephantine monster, evidently allied to the mammoth, was the mastodon, a creature which there is reason to think was contemporary, in america, with the men of prehistoric age. it was so named by baron cuvier to distinguish it from the mammoth, with which it was by others considered identical; and his discrimination of the two forms marked an important and early step in the history of palæontology. the chief difference between these two extinct types lies in their molar teeth. these, on cutting the gum, must have exhibited a number of somewhat conical protuberances of a mammiform appearance; hence the name.[ ] as these points were worn down by mastication, the surface of the tooth showed a series of discs of various sizes. the teeth were covered by a very thick coat of dense, brittle enamel. there are, however, differences in the bony framework of the animal, as well as in its general proportions, which serve to distinguish it from the mammoth; but it will not be necessary to enter into these matters here, for this is difficult ground, even to the student who is well versed in anatomy. notwithstanding a vast amount of observation on the subject, considerable differences of opinion have prevailed among palæontologists with regard to the proper relation of the mastodon to the mammoth and living elephants. [ ] greek--_mastos_, teat; _odous_, _odontos_, tooth. [illustration: fig. .--skeleton _mastodon arvernensis_, pliocene, europe.] at the entrance of the geological gallery in the natural history museum, south kensington, the reader will see a magnificent skeleton of an american mastodon, of which more presently. on this specimen our artist has based his restoration, plate xxi. a large part of the great gallery referred to is devoted to the fossil remains of proboscideans; that is, creatures provided with a long proboscis, or trunk, such as elephants and mastodons. this collection, from widely different quarters, is the largest and most complete in the world. by comparing the specimens of teeth in the cases, and looking at the fine specimens of skulls, and the numerous bones and tusks in the side cases, the reader will carry away a better idea than we can convey by description. fig. shows the skeleton of mastodon arvernensis with two very long tusks. mastodon augustidens had four tusks, two in each jaw, but one of those in the lower jaw sometimes dropped out as the animal grew older. [illustration: plate xxi. the mastodon of ohio, m. americanus.] no genus of quadrupeds has been more extensively diffused over the globe than the mastodon. from the tropics it has extended both north and south into temperate regions, and in america its remains have been discovered as high as latitude ° n. but the true home of the mastodon giganteus, in the united states, like that of m. augustidens in europe, lies in a more temperate zone, and, as professor owen says, we have no evidence that any species was specially adapted, like the mammoth, for braving the rigours of an arctic winter. now, we know from trustworthy geological evidence that the mastodon is a much older form of life than the mammoth. the record of the rocks tells us that it first put in an appearance in an early tertiary period known as the miocene (see table of strata, appendix i.), and in the old world lived on to the end of the succeeding pliocene period. but in america several species, especially m. giganteus, survived till late in the pleistocene period, where it was probably seen by primitive men. this is all that is known about its geographical range, and its antiquity or range in time; some day, perhaps before very long, palæontologists may be able to trace the great proboscideans further back in time, and to show from what form of animal they were derived. strange as it may seem, anatomists declare that they show some remote affinity with the rodents, or gnawing animals, and, in some respects, even with sirenians, such as the manatee (see chapter xvi.). but at present the evolution of this remarkable group of animals is an unsolved problem. those strange animals, the dinocerata, from wyoming, described in chapter x., may perhaps give some indication as to the direction in which we must look for the elephant's ancestors. we noticed that their limbs were decidedly elephantine (see p. ), but they had no trunks, and their skulls showed curious prominences like horn-cores; their teeth too are very different. the visitor to the geological collection at south kensington will also notice a splendid cranium of an elephant, with very long tusks, from the famous sivalik hills of northern india[ ] (stand d on plan). it belonged to elephas ganesa, one of the largest of all the fossil elephants known. the total length of the cranium and tusks is fourteen feet, and the tusks alone measure ten feet six inches in length! this remarkable specimen was presented by sir william erskine baker, k.c.b. [ ] there is some difficulty in determining the precise geological age of the strata in question, on account of the curious mixture of fossil forms of life they contain; but many authorities consider them to be of older pliocene age. but to return to our mastodon. it was early in the eighteenth century that the teeth and bones of the mastodon were first described,[ ] and it is curious to observe how differently scientific discoveries were regarded in those days; for this society of learned men published in these _transactions_ a letter from dr. mather to dr. woodward, in which the former gives an account of a large work in manuscript, but does not name the author. this book, which appears to have been a commentary on the bible, dr. mather recommends "to the patronage of some generous moecenas to promote the publication of it," and transcribes, as a specimen, a passage announcing the discovery at albany, now the capital of new york state, in the year , of enormous bones and teeth. these relics he considered to belong to a former race of giants, and appeals to them in confirmation of genesis vi. ("the nephilim (giants) were in the earth in those days"). [ ] _philosophical transactions of the royal society_, , vol. xxix. portions of the skeleton of mastodon, discovered in , were sent to england and france, and two complete specimens were at length put together in america. one of these was exhibited as a mammoth, in bristol and london, by mr. c. w. peale, a naturalist, by whom they were found in marly clay on the banks of the hudson, near newburgh, in the state of new york. previous to this, in , a french officer, m. de longueil, traversed the virgin forests bordering on the river ohio, in order to reach the mississippi, and the indians who escorted him accidentally discovered, on the borders of a marsh, various bones, some of which seemed to be those of unknown animals. in this turfy marsh, known as the big bone lick, or salt lick, in consequence of the saltness of its waters, herds of wild animals collect together, attracted by the salt, for which they have a great liking. this is probably the reason why so many bones have accumulated here. m. de longueil carried away some bones and teeth, and, on his return to france, presented them to daubenton and buffon. the former declared the teeth to be those of a hippopotamus, and the tusk and gigantic thigh-bone he reported to belong to an elephant. buffon, however, did not share this opinion, and succeeded in converting daubenton, as well as other french naturalists, to his views. he gave to this fossil animal the name of "the elephant of ohio," but formed an exaggerated idea of its size. this discovery produced a great impression in europe. the english, becoming masters of canada by the peace of , sought eagerly for more remains. croghan, the geographer, visited the big bone lick, and found there some more bones of the same kind. he forwarded many cases to different naturalists in london. sir henry howorth, in his recent work, _the mammoth and the flood_ (in which are brought forward certain views not shared by most geologists), mentions that in the shawnee indians found, some three miles from the river ohio, the skeletons of five mastodons, and reported that one of the heads had a long nose attached to it, below which was the mouth. several explorers report discoveries of a like nature, which, if they may be trusted, and if they really refer to the mastodon, and not the mammoth, seem to show that portions of the skin and hairy covering have been seen. if so, their preservation is probably due to the saltness of the waters of this marsh, for salt is a good preservative. in _the american journal of science_,[ ] dr. koch reports the discovery of a mastodon's skeleton, of which the head and fore foot were well preserved, also large pieces of the skin, which looked like freshly tanned leather. but some of these accounts refer to tufts of hair--in one case three inches long. [ ] vol. xxxvi. p. . the great skeleton of mastodon americanus already referred to was purchased by the trustees of the british museum, of mr. albert koch, a well-known collector of fossil remains, who had exhibited it in the egyptian hall, piccadilly, in and , under the name of "the missouri leviathan," an enormous and ill-constructed monster, made up of the bones of this skeleton, together with many belonging to other individuals, in such a way as to horrify an anatomist and appeal all the more forcibly to the imagination of the public. from this heterogeneous assemblage of bones those belonging to the same animal have now been selected and articulated in their proper places. the height of this specimen is nine feet and a half, and the total length about eighteen feet. according to mr. koch, the remains exhibited by him were found in alluvial deposits on the banks of a small tributary of the osage river, in benton county, missouri. the bones were embedded in a brown, sandy deposit, full of vegetable matter, in which were recognised remains of the cypress, tropical cane, swamp moss, etc., and this was covered by blue clay and gravel to a thickness of about fifteen feet. mr. koch personally assured dr. mantell that an indian flint arrow-head was found beneath the leg-bones of this skeleton, and that four similar weapons were embedded in the same stratum. he declared that he took them out of the bed with his own hands. in the pier-case (no. ), near the mastodon americanus, may be seen fifteen heads and jaws, together with other parts of the skeleton, mostly obtained from the same locality, but some of them came from the "big bone lick," kentucky. a fine specimen, obtained from a marsh near newburgh, by dr. warren, measured eleven feet in height, and seventeen in length, while the tusks were nearly ten feet long, not including the portion in the long sockets of the cranium. twenty-six species of mastodon are known. an interesting find was that of dr. barton, a professor of the university of pennsylvania. at a depth of six feet, and under a great bank of chalk, bones of the mastodon were found sufficient to form a skeleton, and in the middle of the bones was seen a mass of vegetable matter enveloped in a kind of sac (which probably was the stomach of the animal). this matter was found to be composed of small leaves and branches, amongst which was recognised a species of rush yet common in virginia. in north america, where the mastodon survived into the period of primitive man, various strange legends exist that seem to refer to it. traditions were rife among the red men concerning this giant form and its destruction. a french officer named fabri informed m. buffon, the naturalist, that the "savages" (indians) regarded the bones found in various parts of canada and louisiana as belonging to an animal which they named "father of the ox." the shawnee indians believed that with this enormous animal there existed men of proportionate development, and that the great being destroyed both with thunderbolts. those of virginia state that as a troop of these terrible animals were destroying the deer, bisons, and other animals created for the use of indians, the great man slew them all with his thunder, except the big bull, who shook off the thunderbolts as they fell on him, till at last, being wounded in the side, he fled towards the great lakes, where he lies to this day. this is one of the songs which fabri heard in canada: "when the great _manitou_ descended to the earth, in order to satisfy himself that the creatures he had created were happy, and he interrogated all the animals, the bison replied that he would be quite contented with his fate in the grassy meadows, where the grass reached his belly, if he were not also compelled to keep his eyes constantly turned towards the mountains to catch the first sight of the 'father of the ox,' as he descended, with fury, to devour him and his companions." many other tribes repeat similar legends. the bones with which mazuyer practised his famous deception were those of a mastodon (see p. ). [illustration: fig. .--head of woolly rhinoceros, partly restored by m. deslongchamps.] contemporary with the mammoth in siberia and in northern and western europe, was the "woolly rhinoceros" (rhinoceros tichorhinus). its body has been found in frozen soil in siberia, with the skin, the two horns, the hair, and even the flesh preserved, as in the case of the mammoth. it had a smooth skin without folds, covered with a fine curly and coarse hairy coat, to enable it to withstand the rigours of an arctic climate. the traveller pallas gives a long account of one of these creatures, which was taken out of the ice, with its skin, hair, and flesh preserved. the following is a brief summary of his narrative. the body was observed in december, , by some jakuts near the river vilui, which discharges itself into the lena below jakutsk in siberia, latitude ° north. it lay in frozen sand upon the banks of the river. a certain russian inspector had sent on to irkutsk the head and two feet of the animal, all well preserved. the rest of it was too much decomposed, and so was left. the head was quite recognisable, since it was covered with its leathery skin. the eyelids had escaped total decay (see fig. ). the skin and tendons of the head and feet still preserved considerable flexibility. he was, however, compelled to cross the baikal lake before the ice broke up, and so could neither draw up a sufficiently careful description nor make sketches of those parts which were sufficiently preserved. plate xxii. is a restoration. [illustration: plate xxii. the woolly rhinoceros, rhinoceros tichorhinus. contemporary with the mammoth.] the rhinoceros in question was neither large for its species nor advanced in age; but it was at least fully grown. the horns were gone, but had left evident traces on the head. the skin which covered the orbits of the eyes and formed the eyelids was so well preserved, that the openings of the eyelids could be seen, though deformed and scarcely penetrable to the finger. the foot that was left--after some parts had unfortunately been burned while left to dry slowly on the top of a furnace--was furnished with hairs. these hairs adhering in many places to the skin, were from one to three lines in length, tolerably stiff and ash-coloured. what remained proved that the foot was covered with bunches of hair hanging down. like the mammoth and the mastodon, its contemporaries, the woolly rhinoceros has given rise to some curious legends. in the city of klagenfurt, in carinthia, is a fountain on which is sculptured the head of a monstrous dragon with six feet, and a head surmounted by a stout horn. according to popular tradition, still prevalent at klagenfurt, this dragon lived in a cave, whence it issued from time to time to frighten and ravage the country. a bold cavalier killed the dragon, paying with his life for this proof of courage. the same kind of legend seems to be current in every country, such as that of the valiant st. george and the dragon, and of st. martha, who about the same time conquered the famous _tarasque_ of the city of languedoc, which bears the name of tarascon. but at klagenfurt the popular legend has happily found a mouthpiece; the head of the pretended dragon killed by the valorous knight is preserved in the hôtel de ville, and this head has furnished the sculptor of the fountain with a model for the head of his statue. herr unger, of vienna, recognised at a glance the cranium of the fossil rhinoceros; its discovery in some cave had probably originated the fable of the knight and the dragon. it is always interesting to discover a scientific basis for fables which otherwise it would be difficult to account for. the same rhinoceros was once a denizen of our country, and its remains are met with in caves and river-gravels. specimens of its skull have also been dredged up by fishermen from the "dogger bank" in the north sea. chapter xv. giant birds. "to discover order and intelligence in scenes of apparent wildness and confusion is the pleasing task of the geological inquirer."--dr. paris. of all the monsters that ever lived on the face of the earth, the giant birds were perhaps the most grotesque. an emu or a cassowary of the present day looks sufficiently strange by the side of ordinary birds; but "running birds" much larger than these flourished not so very long ago in new zealand and madagascar, and must at one time have inhabited areas now sunk below the ocean waves. the history of the discovery of these remarkable and truly gigantic birds in new zealand, and the famous researches of professor owen, by which their structures have been made known, must now engage our attention. in the year professor owen exhibited, at a meeting of the zoological society, part of a thigh-bone, or femur, inches in length, and - / inches in its smallest circumference, with both extremities broken off. this bone of an unknown struthious bird was placed in his hands for examination, by mr. rule, with the statement that it was found in new zealand, where the natives have a tradition that it belonged to a bird now extinct, to which they give the name moa. similar bones, it was said, were found buried on the banks of the rivers. a minute description of this bone was given by the professor, who pointed out the peculiar interest of this discovery on account of the remarkable character of the existing fauna of new zealand, which still includes one of the most extraordinary birds of the struthious order ("running birds"), viz. the apteryx, and also because of the close analogy which the event indicated by the present relic offers to the extinction of the dodo in the island of mauritius. on the strength of this one fragment he ventured to assert that there once lived in new zealand a bird as large as the ostrich, and of the same order. this conclusion was more than confirmed by subsequent discoveries, which he anticipated; and, as we shall see, his estimate was a most moderate one, for the extinct bird turned out to be considerably larger than the ostrich. later on he received from a friend in new zealand news of the discovery of more bones. in a collection of bones of large birds was sent to dr. buckland, dean of westminster, by the rev. william williams, a zealous and successful church missionary, long resident in new zealand. on sending off his consignment mr. williams wrote a letter, of which we give the greater part below. /* "poverty bay, new zealand, february , . "dear sir, */ "it is about three years ago, on paying a visit to this coast--south of the east cape, that the natives told me of some extraordinary monster, which they said was in existence in an inaccessible cavern on the side of a hill near the river wairoa; and they showed me at the same time some fragments of bone taken out of the beds of rivers, which they said belonged to this creature, to which they gave the name moa. "when i came to reside in this neighbourhood i heard the same story a little enlarged; for it was said that this creature _was still existing_ at the said hill, of which the name is wakapunake, and that it is guarded by a reptile of the lizard species [genus]; but i could not learn that any of the present generation had seen it. i still considered the whole as an idle fable, but offered a large reward to any one who would catch me either the bird or its protector...." these offers procured the collection of a considerable number of fossil bones, on which mr. williams, in his letter, makes the following observations:-- "none of these bones have been found on the dry land, but are all of them from the banks and beds of fresh-water rivers, buried only a little distance in the mud.... all the streams are in immediate connection with hills of some altitude. " . this bird was in existence here at no very distant time, though not in the memory of any of the inhabitants; for the bones are found in the beds of the present streams, and do not appear to have been brought into their present situation by the action of any violent rush of waters. " . they existed in considerable numbers"--an observation which has since been abundantly confirmed. " . it may be inferred that this bird was long-lived, and that it was many years before it attained its full size." this is doubtful. " . the greatest height of the bird was probably not less than fourteen or sixteen feet." fourteen is probably the extreme limit. "within the last few days i have obtained a piece of information worthy of notice. happening to speak to an american about these bones, he told me that the bird is still in existence in the neighbourhood of cloudy bay, in cook's straits. he said that the natives there had mentioned to an englishman belonging to a whaling party that there was a bird of extraordinary size to be seen only at night, on the side of a hill near the place, and that he, with a native and a second englishman, went to the spot; that, after waiting some time, they saw the creature at a little distance, which they describe as being about fourteen or sixteen feet high. one of the men proposed to go nearer and shoot, but his companion was so exceedingly terrified, or perhaps both of them, that they were satisfied with looking at the bird, when, after a little time it took alarm, and strode off up the side of the mountain. "this incident might not have been worth mentioning, had it not been for the extraordinary agreement in point of size of the bird"--with his deductions from the bones. "_here_ are the bones which will satisfy you that such a bird _has been_ in existence; and _there_ is said to be the _living bird_, the supposed size of which, given by an independent witness, precisely agrees." in spite, however, of several tales of this kind, it is almost certain that these birds are now quite extinct. the leg-bones sent to london greatly exceeded in bulk those of the largest horse. the leg-bone of a tall man is about ft. in. in length, and the thigh of o'brien, the irish giant, whose skeleton, eight feet high, is mounted in the museum of the royal college of surgeons, is not quite two feet. but some of the leg-bones (tibiæ) of moa-birds measure as much as inches. in and mr. walter mantell, eldest son of dr. mantell, who had resided several years in new zealand, explored every known locality within his reach in the north island. he also went into the interior of the country and lived among the natives for the purpose of collecting specimens, and of ascertaining whether any of these gigantic birds were still in existence; resolving, if there appeared to be the least chance of success, to penetrate into the unfrequented regions, and obtain a live moa. the information gathered from the natives offered no encouragement to follow up the pursuit, but tended to confirm the idea that this race of colossal bipeds was extinct. he succeeded, however, in obtaining a most interesting collection of the bones of moa-birds, belonging to birds of various species and genera, differing considerably in size. this collection was purchased by the trustees of the british museum for £ . another collection was made by mr. percy earle from a submerged swamp, visible only at low water, situated on the south-eastern shore of the middle island. this collection also was purchased by the trustees for the sum of £ . mr. walter mantell, who described this locality, near waikouaiti, seventeen miles north of otago, thinks it was originally a swamp or morass, in which the new zealand flax once grew luxuriantly. the appearance and position of the bones are similar to those of the quadrupeds embedded in peat-bogs, as, for instance, the great irish elk (see next chapter). they have acquired a rich umber colour, and their texture is firm and tough. they still contain a large proportion of animal matter. unfortunately, even when mr. walter mantell visited this spot, the bed containing the bones was rapidly diminishing from the inroads of the sea, and perhaps by this time is entirely washed away. mr. w. mantell, however, obtained fine specimens and feet of a large moa-bird (dinornis) in an upright position; and there seems to be little doubt that the unfortunate bird was mired in the swamp, and perished on the spot. the bones which he obtained from the north island presented a different appearance, being light and porous, and of a delicate fawn-colour. they were embedded in loose volcanic sand. though perfect, they were as soft and plastic as putty, and required most careful handling. they were dug out with great care, and exposed to the air and sun to dry before they could be packed up and removed. the natives were a great source of trouble to him, for as soon as they caught sight of his operations they came down in swarms--men, women, and children, trampling on the bones he had laid out to dry, and seizing on every morsel they could get. the reason of this was that their cupidity and avarice had been excited by the large rewards given by europeans in search of these treasures. mixed with the bones he found fragments of shells, and sometimes portions of the windpipe, or trachea. one portion of an egg which he found was large enough to enable him to calculate the size of the egg when complete. "as a rough guess, i may say that a common hat would have served as an egg-cup for it: what a loss for the breakfast-table! and if many native traditions are worthy of credit, the ladies have cause to mourn the extinction of the moa: the long feathers of its crest were by their remote ancestors prized above all other ornaments; those of the white crane, which now bear the highest value, were mere pigeon's feathers in comparison." the total number of species of moa once inhabiting new zealand was probably at least fifteen, and, judging from the enormous accumulations of their bones found in some districts, they must have been extremely common, and probably went about in flocks. "birds of a feather _flock_ together" (proverb). it is justly concluded, both from the vast number of bones discovered, and from the fact of their great diversity in size and other features, that they must have had the country pretty much to themselves; or, in other words, they enjoyed immunity from the attacks of carnivorous quadrupeds. in whatever way the moas originated in new zealand, it is evident that the land was a favourable one, for they multiplied enormously, and spread from one end to the other. not only was the number of individuals very large, but they belonged (according to mr. f.w. hutton) to no less than seven genera, containing twenty-five different species, a remarkable fact which is unparalleled in any other part of the world. the species described by professor owen in his great work,[ ] vary in size from ft. to or even ft. in height, and differ greatly in their forms, some being tall and slender, and probably swift-footed like the ostrich, whilst others were short and had stout limbs, such as dinornis elephantopus (fig. ), which was undoubtedly a bird of great strength, but very heavy-footed. dinornis crassus also had stout limbs. (see plate xxiii.) [ ] memoir on _the extinct wingless birds of new zealand_. london, . the beautiful drawing by mr. smit (plate xxiv.) is from a photograph in this valuable work representing the late sir richard owen standing in his academic robes by the side of a specimen of the skeleton of the great dinornis maximus. [illustration: plate xxiii. moa-birds. _dinornis giganteus._ _d. elephantopus._ height feet. a smaller species.] [illustration: fig. .--_a._ skeleton of the elephant-footed moa, _dinornis elephantopus_, from new zealand. _b._ leg-bones of _dinornis giganteus_, representing a bird over ft. high. _r_, _b_, footprints.] the natural history museum at south kensington contains a valuable collection of remains of moa-birds. these skeletons may be seen in gallery no. (at the end of the long gallery) in the glass cases r, r´, and s. dinornis elephantopus (elephant-footed) is in front of the window. in d. giganteus the leg-bone (see fig. ) attains the enormous length of ft., and in an allied species it is even in.! the next bone below (cannon bone) is sometimes more than half the length of the leg-bone (tibia). a skeleton in one of the glass cases has a height of about - / ft., and it is concluded that the largest birds did not stand less than ft., and possibly were ft. high! dinornis parvus (the dwarf moa) was only three feet high. in the trustees obtained, from a cave in otago, the head, neck, two legs, and feet of a moa (d. didinus), having the skin, still preserved in a dried state, covering the bones, and some few feathers of a reddish hue still attached to the leg (table case ). the rings of the windpipe may be seen _in situ_, the sclerotic plates of the eye, and the sheaths of the claws. one foot also shows the hind claw still attached. from traditions and other circumstances it is supposed that the present natives of new zealand came there not more than about six hundred years ago, and there is reason to believe that the ancient maoris, when they landed, feasted on moa-birds as long as any remained. their extermination _probably_ only dates back to about the period at which the islands were thrice visited by captain cook, - . the moa-bird is mixed up with their songs and stories, and they even have a tradition of caravans being attacked by them. still, some people believe that they were killed off by the race which inhabited new zealand before the maoris came. but they must have been there up to a time not far removed from the present. it is even said that the "runs" made by them were visible on the sides of the hills up to a few years ago; and possibly they may still be visible. the charred bones and egg-shells have been found mixed with charcoal where the native ovens were formerly made, and their eggs are said to have been found in maori graves. mr. hutton considers that in the north island they were exterminated three or four centuries ago, while in the south island they may have lingered a century longer. the nearest ally of the moa is the small apteryx, or kiwi, of new zealand, specimens of which may be seen at the natural history museum, at the end of the long gallery devoted to living birds. this bird, however, has a long pointed bill for probing in the soft mud for worms, whereas the bill of the moa was short like that of an ostrich. another difference between the two is that, while the kiwi still retains the rudiments of wing-bones, the moa had hardly a vestige of such. in australia the remains have been found of a bird probably related to the cassowaries, but at present imperfectly known. to this type of struthious, or running bird, the name dromornis has been given. now, it is a remarkable fact that remains of another giant bird and its eggs have been found on the opposite side of the great indian ocean, namely, in the island of madagascar, the existence of which was first revealed by its eggs, found sunk in the swamps, but of which some imperfect bones were afterwards discovered. one of these eggs was so enormous that its diameter was nearly fourteen inches, and was reckoned to be as big as three ostrich eggs, or hen's eggs! this means a cubic content of more than two gallons! the natives search for the eggs by probing in the soft mud of the swamps with long iron rods. a large and perfect specimen of an egg of this bird, such as was recently exhibited at a meeting of the zoological society, is said to be worth £ . what the dimensions of Æpyornis were it is impossible to say, and it would be unsafe to venture a calculation from the size of the egg.[ ] the reader who wishes to see some of the remains of this huge bird may be referred to the natural history museum. in wall case no. , gallery (geological department), may be seen a tibia and plaster casts of other bones; also two entire eggs, many broken pieces, and one plaster cast of an egg found in certain surface deposits in madagascar. in the same case may be seen bones of the dodo from the isle of mauritius. unlike new zealand, madagascar possesses no living wingless bird. but in the neighbouring island of mauritius the dodo has been exterminated less than three centuries ago. the little island of rodriguez, in the same geographical province, has also lost its wingless solitaire. [ ] from the size of a femur and tibia of _Æpyornis_ preserved in the paris museum, it could not have been less in stature than the dinornis elephantopus of new zealand. it will thus be seen that we have three distinct groups of giant land birds--the moas, the dromornis, and the Æpyornis,--occupying areas at present widely separated by the ocean. this raises the difficult but very interesting question, how they got there; and the same applies to their living ancestors. the ostrich proper, struthio camelus, inhabits africa and arabia; but there is evidence from history to show that it formerly existed in beluchistan and central asia. and, going still further back, the geological record informs us that, in the pliocene period, they inhabited what is now northern india. in australia we have the cassowary (casuarius) and the emeu (dromaius); in new zealand, the apteryx (or kiwi). now, as none of these birds can either fly or swim, it is impossible that they could have reached these regions separated as they now are; and it is hardly likely that they arose spontaneously in each district from totally different ancestors. but the new doctrine of evolution affords a key to the problem, and tells us that they all sprang from a common ancestor, of the struthious type (probably inhabiting the great northern continental area), and gradually migrated south along land areas now submerged. in this way we get some idea of the vast changes that have taken place in the geography of the world during later geological periods. perhaps they were compelled to move south until they reached abodes free from carnivorous enemies. having done so, they evidently flourished abundantly, especially in new zealand, where there are so few mammals, except those recently introduced by man. in north america professor cope has reported a large wingless fossil bird from the eocene strata of new mexico. in england we have two such--namely, the dasornis, from the london clay of sheppey (eocene period), and the gastornis, from the woolwich beds near croydon, and from paris (also eocene). it will thus be seen that big struthious birds have a long history, going far back into the tertiary era, and that they once had a much wider geographical range than they have now. doubtless, future discoveries will tend to fill up the gaps between all these various types, both living and extinct, and to connect them together in one chain of evolution. the last great find of moa-birds in new zealand took place only last year, and was reported by a correspondent to the _scotsman_ (november , ), writing from oamaru. in the letter that appeared at the above date, our friend mr. h. o. forbes announces the discovery of an immense number of bones, estimated to represent at least five hundred moas! they were found in the neighbourhood of oamaru. and, after some preliminary remarks, he continues as follows:-- "the part of the field on which the remains were found bears no traces of any physical disturbance--_e.g._ of earthquake, or flood, or hurricane--that would account for the sudden destruction of a flock or 'mob' of moas. the moa, when alive, carried in its crop--like our own hens--a quantity of stones to serve as a private coffee-mill for digestive grinding; stones which, being somewhat in proportion to the magnitude of the giant bird, form, when found in one place, a 'heap' of stones which are easily identified as a moa heap, and nothing else. and in the present case the heap was here and there found in such relation to the bones of an individual bird as to show that the moa must have died on that spot, and remained there quietly undisturbed. further, the number of birds represented by the exhumed remains is so great that the living birds could not have stood together on the space of ground on which the remains were found lying. and there is not on any of the bones any trace of such violence as must have left its mark if the death of the birds had been caused by a moa-hunting mankind. finally, it does not appear that in this particular district there ever has been, at any traceable period of the physical history of the land, a forest vegetation, such as might suggest that the catastrophe was caused by fire. "the question how to account for the slaughter is raised likewise by two previous finds of moa bones. the first of these, at glenmark, in canterbury, was the most memorable, because, being the first, it made the deepest impression. the second great find, far inland, up the molineux river, otherwise the clutha, was beneath the diluvium that is now worked by the gold-digger. the spot must have been the site of a lagoon, at one point of which there was a spring. round about this point there were found the remains of, it was reckoned, five hundred individual moas. the bones were quietly _laid_ there, with, in some cases, the 'heap' of digestive stones _in situ_ along with the skeletons. and mr. booth, whose elaborate investigation of this case is recorded in the annual volume of _the new zealand institute_, suggested the theory that the climate of new zealand was changing to a degree of cold intolerable to moa nature; and that the birds, fleeing from its rigour, sought comfort in the spring of water, sheltering their featherless breast in it, and so dozing out of this troubled life. and in this new find the wonder comes back unmitigated, as a mystery unsolved. for here is no bog deep enough, as in the first instance, nor lagoon spring, as in the second, to account for that multitude of giant birds dying in one spot. "another curious puzzle is, on close inspection, found everywhere in the moa bone discoveries. it is hardly possible to make sure that the bones of any one complete moa skeleton all belong to the same individual i heard some one say the other day that it is not certain that any moa in any earthly museum has all his own bones, and only his own. "a main interest of such a find lies not in the power of supplying museums with specimens of what is rapidly disappearing from the face of the world, but in the possibility of finding species of moa that have not hitherto been tabulated. whether any new species have been brought to light on this occasion the experts will not say until there has been time to make a careful study of the bones, nor do they venture on any theory to account for there being so many individual birds dead in that one place, where there appears to be no room for the explanations offered in connection with previous great finds. the date of these birds appears to be earlier than that of the coming of the maoris into new zealand, say five or six hundred years ago, as the maori memory appears to have in it no trace of feasting on these giant moas, but celebrates the rat-hunt in its ancient heroic song. and your readers may picture their appearance by noticing the fact that one of the recently found bones must have belonged to a moa fourteen feet high!" note.--for further information on this interesting subject, the reader is referred to a paper in _natural science_, october, , by mr. f. w. hutton. in a valuable paper, read before the royal geographical society by mr. h. o. forbes, march , , the lecturer alluded to the important fact that bone belonging to big extinct struthious birds have been discovered in patagonia. this is interesting news as bearing upon the theory of a former antarctic continent connecting australia and new zealand with south africa, and perhaps even with south america. after the lecture, to which we listened with great interest, the subject was discussed by mr. slater, dr. günther, and dr. henry woodward. for ourselves we can see no great difficulty in accepting the theory that such a continent once existed, though it is out of harmony with the now rather fashionable theory of "the permanence of ocean basins"--a doctrine which seems to have been pressed too far. chapter xvi. the great irish deer and steller's sea-cow. "and, above all others, we should protect and hold sacred those types, nature's masterpieces, which are first singled out for destruction on account of their size, or splendour, or rarity, and that false detestable glory which is accorded to their most successful slayers. in ancient times the spirit of life shone brightest in these; and when others that shared the earth with them were taken by death they were left, being more worthy of perpetuation. like immortal flowers they have drifted down to us on the ocean of time, and their strangeness and beauty bring to our imaginations a dream and a picture of that unknown world, immeasurably far removed, where man was not: and when they perish, something of the gladness goes out of nature, and the sunshine loses something of its brightness."--w. h. hudson, in _the naturalist in la plata_. among the extinct animals of prehistoric times the "great irish elk,"[ ] as it is generally called, deserves special notice, both from the enormous size of its antlers, and from the fact that its remains are exceedingly plentiful in ireland. [ ] the term "elk" is misleading, for it is not an elk (_alces_) at all, but a true _cervus_ (stag). it should be called "the great irish deer." this magnificent creature, so well depicted by our artist (plate xxv.), was, however, by no means confined to ireland; its remains are found in many parts of great britain, particularly in cave deposits, and also on the continent. some writers think that it was contemporary with men in ireland; it may have been so, but at present the question cannot be considered as proved. mr. r. j. ussher, who found its remains in a cave near cappagh, cappoquin, thinks he has obtained evidence to show that it was hunted by man at the time when he hunted reindeer in this part of europe, but the age of the strata containing the remains is doubtful. again, there is a rib in the dublin museum with a perforation which is sometimes taken to be the result of a wound from a dart, arrow, or spear; but the wound may have been inflicted by one of the sharp tynes in a fight between two bucks. dr. hart mentions the discovery of a human body in gravel, under eleven feet of peat, soaked in bog-water, in good preservation, and completely clothed in antique garments of hair, which it has been conjectured might be that of the great deer. but if some individual animal had perished and left its body under the like circumstances, its hide and hair ought equally to have been preserved. dr. molyneux, to whom we owe the first account of its discovery, says that its extinction in ireland has occurred "so many ages past, as there remains among us not the least record in writing, or any manner of tradition, that makes so much as mention of its name; as that most laborious inquirer into the pretended ancient but certainly fabulous history of this country, mr. roger o'flaherty, the author of _ogygia_, has lately informed me."[ ] [ ] _philosophical transactions_, vol. xix. p. . in the romance of the "niebelungen," now immortalised by wagner, which was written in the thirteenth century, the word _shelch_ occurs, and is applied to one of the beasts slain in a great hunt a few hundred years before that time in germany. this word has been cited by some naturalists as probably signifying the great irish deer. but this is mere conjecture, and the word might apply to some big red deer. the total silence of cæsar and tacitus respecting such remarkable animals renders it highly improbable that they were known to the ancient britons. [illustration: fig. .--skeleton of great irish deer, _cervus giganteus_, from shell-marl beneath the peat, ireland. antlers over feet across.] two entire skeletons of the male, with antlers measuring a little over nine feet from tip to tip, and one skeleton of the hornless doe, are to be seen set up in the middle of the long gallery no. at the natural history museum. the drawing in fig. is from a specimen in the museum of the royal college of surgeons (lincoln's inn fields). the height of this specimen to the summit of the antlers is ft. in. the span of the antlers, from tip to tip, is ft. (in the living moose it is only ft). the weight of the skull and antlers together is lbs., but those of another specimen belonging to the royal dublin society weigh lbs. this great extinct deer surpassed the largest wapite (cervus canadensis) in size, and its antlers were very much larger, wider, and heavier. in some cases the antlers have measured more than ft. from tip to tip. the body of the animal, as well as its antlers, were larger and stronger than in any existing deer. the limbs are stouter, as might be expected from the great weight of the head and neck. another and more striking feature is the great size of the vertebræ of the neck; this was necessary in order to form a column capable of supporting the head and its massive antlers. (see plate xxv.) [illustration: plate xxv. the great irish deer, cervus megaceros. height to the summit of the antlers feet; spread of antlers feet.] the first tolerably perfect skeleton was found in the isle of man, and presented by the duke of athol to the edinburgh museum. it was figured in cuvier's _ossemens fossiles_. besides those already mentioned at south kensington and dublin, there is one in the woodwardian museum at cambridge. it cannot be doubted that, like all existing deer, the animal shed its antlers periodically, and such shed antlers have been found. when it is recollected that all the osseous matter of which they are composed must have been drawn from the blood carried along certain arteries to the head, in the course of a few months, our wonder may well be excited at the vigorous circulation that took place in these parts. in the red deer the antlers, weighing about lbs., are developed in the course of about ten weeks; but what is that compared to the growth of over lbs. weight in some three or four months? it is a mistake to suppose that the remains discovered in ireland were found in peat; they occur not in the peat, but in shell-marls and in clays _under the peat_. this is an important point for if the remains _were_ found in the peat, they would prove that the great deer survived into a later period; instead of being (as is believed from geological evidence) contemporary with the mammoth and woolly rhinoceros in this country, and then disappearing from view. as already stated, it existed on the continent, and may there have been exterminated by man. mr. w. williams, who has explored several peat-bogs in ireland, marking the site of ancient lakes, and found many specimens in beds underlying the peat, has given much interesting information bearing upon the question of the period when the great deer inhabited ireland, and the manner in which it was preserved in the lake-beds.[ ] he spent ten weeks in - , excavating deer remains in the bog of ballybetagh, and subsequently made similar excavations in the counties of mayo, limerick, and meath. these peat-bogs occupy the basins of lakes, the deeper hollows of which have long since been silted up with marls, clays, and sands, and in this silt, or mud, the plants which produced the peat grew. in all the bogs examined he found a general resemblance in the order of succession of the beds, with only slight variations in the nature of the materials such as might be easily accounted for by differences in the surrounding rocks. in these deposits the geologist may read, as in a book, the successive changes in climate that have taken place since the time when the country was deeply covered with snow and ice during the glacial period. [ ] _geological magazine_, new series, vol. viii. ( ), p. . he found at the bottom of the old ballybetagh lake, and resting on the true boulder clay (a product of the ice-sheet), a fine stiff clay which seems to have been brought in by the action of rain washing fine clay out of the boulder clay, that nearly covered the land, and depositing it in the lake. this action probably took place during a period of thaw, when the climate was damp, from the melting of so much ice, and the rainfall considerable. then the climate improved, the cold of the glacial period passed away, and the climate became warm. during this phase the next stratum was formed, consisting chiefly of vegetable remains. the summers must have been unusually warm, dry, and favourable to the growth of vegetation on the bed of the lake. about this time the great irish deer appeared on the scene, for its remains were found resting on this layer, or stratum, in a brownish clay. this deposit also was the product of a time when the climate was mild. it is a true lake-sediment, with seams of clay and fine sand, the latter having been brought down by heavy rainfall from the hills, just as at the present day. now, we have to consider how these great deer got buried in this deposit. how did they get drowned? they may have gone into the lakes to escape from wolves, or possibly to escape from ancient britons (but that is still doubtful). perhaps they went into the water to wallow, as is usual with deer, or they may have ventured to swim the lakes (see p. ). to enter the lake from a sandy shore would be easy enough, but, on reaching the other side, they might find a soft mud instead, into which their small feet would sink; and the more they plunged and struggled, the worse became their plight, until at last, weary and exhausted, the heavy antlers pressed their heads down under the water, and they were drowned. it does not follow, according to this theory, that either the entire animal ought to be found, or even its legs, sticking in the clay. for a few days it might remain so, but the motion of the waters of the lake would sway the body to and fro, while the gases due to decomposition would render it buoyant, and perhaps raise it bodily off the bottom. then it might float before the wind, its head hanging down, till it reached the lee-side of the lake. then the antlers would get fastened in mud near the shore, thus mooring the body until at last so much of the flesh of the neck had decayed that the body got separated from it, leaving the head and antlers near the shore. nearly a hundred heads had been found in this lake previous to mr. williams's explorations, and yet scarcely six skeletons. at first it is somewhat puzzling to account for this scarcity of skeletons compared with heads; but very likely the bodies, minus their heads, were carried right out of the lake, down a river, and perhaps reached the sea or got stranded somewhere down the river in such a way that the bones were never covered up. but in the limerick bogs heads and skeletons were often found together. in that district the lakes were probably shallow and with but a feeble current, and so the body never floated away. this explanation by mr. williams seems satisfactory. he reports that the female skulls were rarely met with. either they were more timid in swimming lakes, or, having no antlers, they may have succeeded in getting out, or the care of their young ones may have kept them out of the lakes during the summer months. the clay in which the remains occur is succeeded by another bed of pure clay, which _never_ yields any skulls or bones. this, mr. williams thinks, was deposited at a time when the climate was more or less severe, and the musk-ox, reindeer, and other arctic animals came down from more northern regions, even down to the south of france. he concludes that this period marks the extinction of the great deer in ireland, whether rightly or wrongly it is hard to say. many observers are inclined to think that it lived on to a later period. an interesting fact, having some bearing on the question, is this: that the bones in some cases even yet retain their marrow in the state of a fatty substance, which will burn with a clear lambent flame. evidence such as this seems to point to a more recent date for its extinction. steller's sea-cow.[ ] [ ] for fuller information, see the _geological magazine_, decade iii. vol. ii. p. . paper by dr. henry woodward, f.r.s. the sirenia of the present day form a remarkable group of aquatic herbivorous animals, really quite distinct from the cetacea (whales and dolphins), although sometimes erroneously classed with them. in the former group are the dugong and the manatee. these creatures pass their whole life in the water, inhabiting the shallow bogs, estuaries, and lagoons, and large rivers, but never venturing far away from the shore. they browse beneath the surface on aquatic plants, as the terrestrial herbivorous mammals feed upon the green pastures on land. not a few of the tales of mermen and mermaids owe their origin to these creatures, as well as to seals, and even walruses. the portuguese and spaniards give the manatee a name signifying "woman-fish," and the dutch call the dugong the "little bearded man." a very little imagination, and a memory only for the marvellous, doubtless sufficed to complete the metamorphosis of the half-woman, or man, half-fish, into a siren, a mermaid, or a merman. hence the general name sirenia. the manatee (_manatus_) inhabits the west coast and rivers of tropical africa, and the east coast and rivers of tropical america, the west indies, and florida. the dugong (_halicore_) extends along the red sea coasts, the shores of india, and the adjacent islands, and goes as far as the northern and eastern coasts of australia. [illustration: fig. .--skeleton of _rhytina gigas_ (steller's "sea-cow"), from a peat deposit, behring's island.] the most remarkable sirenian is the rhytina gigas, or "steller's sea-cow." early in the trustees of the british museum acquired a nearly complete skeleton of this animal, now extinct, from peat deposits in behring's island, of pleistocene age. formerly it was abundant along the shores of kamtchatka, the kurile islands, and alaska. it was first discovered by the german naturalist, steller, who, in company with vitus behring, a captain in the russian navy and a celebrated navigator of the northern seas, was with his vessel and crew cast away upon behring's island (where behring died) in . steller's original description is preserved in the _memoirs of the academy of sciences st. petersburg_. he saw it alive during his long enforced residence on the island. in the course of forty years, - , it appears to have been exterminated, probably for the sake of its flesh and hide, around both behring's island and copper island, to the shores of which it was, in steller's time, limited. fig. shows its skeleton, ft. in. long, now preserved in the geological collection at south kensington (glass-case n). the skeletons are found, in the islands, at a distance from the shore in old raised beaches and peat-mosses, deeply buried and thickly overgrown with grass. they are discovered by boring into the peat with an iron rod, just as timber is found in irish peat-bogs. (see restoration, plate xxvi.) steller records that when he came to behring's island, the sea-cows fed in the shallows along the shore, and collected in herds like cattle. every few minutes they raised their heads in order to get more air before descending again to browse on the thick sea-weed (probably laminaria) surrounding the coast. with regard to their habits, they were very slow in their movements: mild and inoffensive in disposition. their colour was dark brown, sometimes varied with spots. the skin was naked; but thick, hard, and rugged. they are said to have sometimes reached a length of thirty-five feet, when full grown. most of their time was spent in browsing, and whilst so occupied, were not easily disturbed. their attachment to each other was great, so that when one was harpooned, the others made great attempts to rescue it. according to steller, they were so heavy that it required forty men with ropes to drag the body of one to land. [illustration: plate xxvi. steller's sea-cow, rhytina gigas. found alive by steller at behring's island. length feet inches.] when, in , the news of the discovery of behring island reached kamtchatka, several expeditions were fitted out for the purpose of hunting the sea-cow and the various fur-bearing animals, such as the sea-otter, fur seal, and blue fox, which are found there; and very soon many whaling vessels began to stop there to lay in a supply of sea-cow meat for food. so great was the destruction wrought by these whalers and fur-hunters that in , only thirteen years after its discovery, the sea-cow had become practically exterminated. in , according to the investigations of dr. l. stejneger of the u. s. national museum, washington, who has made a most careful study of the question, this large and important marine mammal became wholly extinct, the last individual ever seen alive having been killed in that year; and the fate which overtook rhytina so speedily has almost become that of the buffalo, and will as certainly become that of the fur seal unless it be protected. it may interest the reader, especially if he be a traveller, to know that, besides the fine specimen of rhytina in the natural history museum, already alluded to, good skeletons are possessed by the museums of st. petersburg, helsingsfors (finland), stockholm, u. s. national museum, washington, as well as portions of skeletons by other museums. the sirenians are an ancient race, for their remains have been found in tertiary strata, of various ages, from eocene to pleistocene, over the greater part of europe--in england, holland, belgium, france, germany, austria, and italy; also near cairo. in the new world, fossil sirenians have been found in south carolina, new jersey, and jamaica. another european species is the halitherium, from the miocene rocks of hesse-darmstadt, of which a cast may be seen in the natural history museum, south kensington. its length is ft. in. the teeth in this form resembled those of the dugong. the rhytina was probably intermediate between the dugong and the manatee, judging from the casts of its brain-cavity. its brain was very small considering the size of the animals. altogether, as many as fourteen fossil genera and thirty species are known. evidently, then, the old sirenia were once a much more flourishing race. at present, they are confined exclusively to the tropical regions of the earth, and their past distribution, as revealed to the geologists, adds one more proof to the now well-established fact, that throughout most of the tertiary era the climate of northern latitudes was very much warmer than now--in fact, sub-tropical. what cause, or causes, brought about so great a change, we cannot stay to consider here. in conclusion, it only remains to express a hope that the reader may have been interested in our humble endeavours to describe some of the largest, most strange, and wonderful forms of life that in remote ages have found a home on this planet. and perhaps a few of our readers may be induced to add a new and never-failing interest to their lives by searching in the stony record for traces of the world's "lost creations." if so, our labour will not have been in vain. appendix i. table of stratified rocks. ------------------------------------------------------------------------ periods. | systems. | formations. | ------------+------------------+-------------------------------+-------- quaternary. | {|terrestrial, alluvial, | |=recent= {| estuarine, and marine beds of | | {| historic, iron, bronze, and | | {| neolithic ages | | | | | {|peat, alluvium, loess |dominant | {|valley gravels, brickearths | type, | {|cave-deposits |man |=pleistocene= {|raised beaches | | {|palæolithic age | | {|boulder clay and gravels | ------------+------------------+-------------------------------+-------- cainozoic. | {|norfolk forest-bed series | tertiary. |=pliocene= {|norwich and red crags | | {|coralline crag (diestian) | | | | |=miocene= |oeningen beds freshwater, etc. | | | | | {|fluvio-marine series | | {| (oligocene) |dominant |=eocene= {|bagshot beds }(nummulitic | types, | {|london tertiaries } beds) |birds ------------+------------------+-------------------------------| and secondary, | {|maestricht beds |mammals or mesozoic.| {|chalk | |=cretaceous= {|upper greensand | | {|gault | | {|lower greensand } neocomian | | {|wealden } | |------------------+-------------------------------+-------- | {|purbeck beds | | {|portland beds | | {|kimmeridge clay | | {| (solenhofen beds) | |=jurassic= {|corallian beds | | {|oxford clay |dominant | {|great oolite series | type | {|inferior oolite series |reptilia | {|lias | |-------------- ---+-------------------------------| | {|rhætic beds | |=triassic= {|keuper | | {|muschelkalk | | {|bunter | ------------+------------------+-------------------------------+-------- primary, |=permian or {|red sandstone, marl } | or |dyas= {|magnesian limestone, }zechstein| | {| etc. } |dominant palÆozoic. | {|red sandstone and conglomerate | type, | {|rothliegende |fishes | | | |=carboniferous= {|coal measures and millstone | | {| grit | | {|carboniferous limestone series | | | | |=devonian & old {|upper old red sandstone | | red sandstone= {|devonian | | {|lower old red sandstone | | | | |=silurian= {|ludlow series | | {|wenlock series | | {|llandovery series | | {|may hill series | | | | |=ordovician= {|bala and caradoc series | | {|llandeilo series | | {|llanvirn series | | {|arenig and skiddaw series | | | | |=cambrian= {|tremadoc slates | | {|lingula flags | | {|menevian series | | {|harlech and longmynd series | ------------+------------------+-------------------------------+-------- |=eozoic-archÆan= {|pebidian, arvonian, and |dominant | {| dimetian | type, | {|huronian and laurentian |inverte- | | | brata ------------+------------------+-------------------------------+-------- appendix ii. the great sea-serpent. mr. henry lee, formerly naturalist to the brighton aquarium, discusses the question of "the great sea-serpent" in an interesting little book, entitled _sea monsters unmasked_, illustrated ( ), published as one of the handbooks issued in connection with the international fisheries exhibition. he goes fully into the history of the subject, and shows how some of the appearances described may be accounted for; but yet is inclined to think that there may exist in the sea animals of great size unknown to science, and concludes as follows:-- "this brings us face to face with the question, 'is it, then, so impossible that there may exist some great sea creature, or creatures, with which zoologists are hitherto unacquainted, that it is necessary in every case to regard the authors of such narratives as wilfully untruthful or mistaken in their observations, if their descriptions are irreconcilable with something already known?' i, for one, am of the opinion that there is no such impossibility. calamaries or squids of the ordinary size have, from time immemorial, been amongst the commonest and best known of marine animals in many seas; but only a few years ago any one who expressed his belief in one formidable enough to capsize a boat or pull a man out of one was derided for his credulity, although voyagers had constantly reported that in the indian seas they were so dreaded that the natives always carried hatchets with them in their canoes, with which to cut off the arms or tentacles of these creatures, if attacked by them. we now know that their existence is no fiction; for individuals have been captured measuring more than fifty feet, and some are reported to have measured eighty feet in total length. as marine snakes some feet in length, and having fin-like tails adapted for swimming, abound over an extensive range, and are frequently met with far at sea, i cannot regard it as impossible that some of these also may attain to an abnormal and colossal development. dr. andrew wilson, who has given much attention to this subject, is of the opinion that 'in this huge development of ordinary forms we discover the true and natural law of the production of the giant serpent of the sea.' it goes far at any rate towards accounting for its supposed appearance. i am convinced that whilst naturalists have been searching amongst the vertebrata for a solution of the problem, the great unknown, and therefore unrecognised, calamaries, by their elongated cylindrical bodies and peculiar mode of swimming, have played the part of the sea-serpent in many a well-authenticated incident. in other cases, such as those mentioned by 'pontoppidan' (_history of norway_), the supposed vertical undulations of the snake seen out of water have been the burly bodies of so many porpoises swimming in line--the connecting undulations beneath the surface have been supplied by the imagination. the dorsal fins of basking sharks, as figured by dr. andrew wilson, may have furnished the 'ridge of fins;' an enormous conger is not an impossibility; a giant turtle may have done duty, with its propelling flippers and broad back; or a marine snake of enormous size may really have been seen. but if we accept as accurate the observations recorded (which i certainly do not in all cases, for they are full of errors and mistakes), the difficulty is not entirely met, even by this last admission, for the instances are very few in which an ophidian proper--a true serpent--is indicated. there has seemed to be wanting an animal having a long snake-like neck, a small head, and a slender body, and propelling itself by paddles. "the similarity of such an animal to the plesiosaurus of old was remarkable. that curious compound reptile, which has been compared with 'a snake threaded through the body of a turtle,' is described by dean buckland as having 'the head of a lizard, the teeth of a crocodile, a neck of enormous length resembling the body of a serpent, the ribs of a chameleon, and the paddles of a whale.' in the number of its cervical vertebræ (about thirty-three) it surpasses that of the longest-necked bird, the swan. "the form and probable movements of this ancient saurian agree so markedly with some of the accounts given of 'the great sea-serpent,' that mr. edward newman advanced the opinion that the closest affinities of the latter would be found to be with the enaliosaurians, or marine lizards, whose fossil remains are so abundant in the oolite and the lias. this view has been taken by other writers, and emphatically by mr. gosse. neither he nor mr. newman insist that 'the great unknown' must be the plesiosaurus itself. mr. gosse says, 'i should not look for any species, scarcely for any genus, to be perpetuated from the oolitic period to the present. admitting the actual continuation of the order enaliosauria, it would be, i think, quite in conformity with general analogy to find some salient features of several extinct forms.' "the form and habits of the recently recognised gigantic cuttles account for so many appearances which, without knowledge of them, were inexplicable when mr. gosse and mr. newman wrote, that i think this theory is not forced upon us. mr. gosse well and clearly sums up the evidence as follows: 'carefully comparing the independent narratives of english witnesses of known character and position, most of them being officers under the crown, we have a creature possessing the following characteristics: ( ) the general form of a serpent; ( ) great length, say above sixty feet; ( ) head considered to resemble that of a serpent; ( ) neck from twelve to sixteen inches in diameter; ( ) appendages on the head, neck, or back, resembling a crest or mane (considerable discrepancy in details); ( ) colour, dark brown or green, streaked or spotted with white; ( ) swims at surface of the water with a rapid or slow movement, the head and neck projected and elevated above the surface; ( ) progression steady and uniform, the body straight, but capable of being thrown into convolutions; ( ) spouts in the manner of a whale; ( ) like a long "nun-buoy."' he concludes with the question, 'to which of the recognised classes of created beings can this huge rover of the ocean be referred?' "i reply, 'to the cephalopoda.' there is not one of the above judiciously summarised characteristics that is not supplied by the great calamary, and its ascertained habits and peculiar mode of locomotion. "only a geologist can fully appreciate how enormously the balance of probability is contrary to the supposition that any of the gigantic marine saurians of the secondary deposits should have continued to live up to the present time. and yet i am bound to say that this does not amount to an impossibility, for the evidence against it is entirely negative. nor is the conjecture that there may be in existence some congeners of these great reptiles inconsistent with zoological science. dr. j. e. gray, late of the british museum, a strict zoologist, is cited by mr. gosse as having long ago expressed his opinion that some undescribed form exists which is intermediate between the tortoises and the serpents." (this is quoted by mr. lee in a footnote.) "professor agassiz, too, is adduced by a correspondent of the _zoologist_ (p. ), as having said concerning the present existence of the enaliosaurian type, that 'it would be in precise conformity with analogy that such an animal should exist in the american seas, as he had found numerous instances in which the fossil forms of the old world were represented by living types in the new.' "on this point, mr. newman records in the _zoologist_ (p ), an actual testimony which he considers 'in all respects the most interesting natural history fact of the present century.' he writes-- "'captain the hon. george hope states that when in h.m.s. _fly_, in the gulf of california, the sea being perfectly calm, he saw at the bottom a large marine animal with the head and general figure of the alligator, except that the neck was much longer, and that instead of legs the creature had four large flappers, somewhat like those of turtles, the anterior pair being larger than the posterior, the creature was distinctly visible, and all its movements could be observed with ease; it appeared to be pursuing its prey at the bottom of the sea; its movements were somewhat serpentine, and an appearance of annulations, or ring-like divisions of the body, was distinctly perceptible. captain hope made this relation in company, and as a matter of conversation. when i heard it from the gentleman to whom it was narrated, i inquired whether captain hope was acquainted with those remarkable fossil animals, ichthyosauri and plesiosauri, the supposed forms of which so nearly corresponded with what he describes as having seen alive, and i cannot find that he had heard of them; the alligator being the only animal he mentioned as bearing a partial similarity to the creature in question.' "unfortunately, the estimated dimensions of this creature are not given. "that negative evidence alone is an unsafe basis for argument against the existence of unknown animals, the following illustrations will show:-- "during the deep-sea dredgings of h.m.s. _lightning_, _porcupine_, and _challenger_, many new species of mollusca and others, which had been supposed to have been extinct ever since the chalk, were brought to light; and by the deep-sea trawlings of the last-mentioned ship there have been brought up from great depths fishes of unknown species, and which could not exist near the surface, owing to the distention and rupture of their air-bladder when removed from the pressure of deep water. "mr. gosse mentions that the ship in which he made the voyage to jamaica was surrounded in the north atlantic, for seventeen continuous hours, by a troop of whales of large size, of an undescribed species, which on no other occasion has fallen under scientific observation. unique specimens of other cetaceans are also recorded. "we have evidence, to which attention has been directed by mr. a. d. bartlett, that 'even on land there exists at least one of the largest mammals, probably in thousands, of which only one individual has been brought to notice, namely, the hairy-eared, two-horned rhinoceros (_r. lasiotis_), now in the zoological gardens, london. it was captured in , at chittagong, in india, where for years collectors and naturalists have worked and published lists of the animals met with, and yet no knowledge of this great beast was ever before obtained, nor is there any portion of one in any museum. it remains unique. "i have arrived at the following conclusions: . that without straining resemblances, or casting a doubt upon narratives not proved to be erroneous, the various appearances of the supposed 'great sea-serpent' may now be nearly all accounted for by the forms and habits of known animals; especially if we admit, as proposed by dr. andrew wilson, that some of them, including the marine snakes, may, like the cuttles, attain to extraordinary size. . that to assume that naturalists have perfect cognisance of every existing marine animal of large size, would be quite unwarrantable. it appears to me more than probable that many marine animals, unknown to science, and some of them of gigantic size, may have their ordinary habitat in the sea, and only occasionally come to the surface; and i think it not impossible that amongst them may be marine snakes of greater dimensions than we are aware of, and even a creature having close affinities with the old sea-reptiles whose fossil skeletons tell of their magnitude and abundance in past ages. "it is most desirable that every supposed appearance of 'the great sea-serpent' shall be faithfully noted and described; and i hope that no truthful observer will be deterred from reporting such an occurrence by fear of the disbelief of naturalists or the ridicule of witlings." appendix iii. list of british localities where remains of the mammoth have been discovered.[ ] [ ] from mr. leith adams's monograph on _british fossil elephants_. palæontographical society, london. . . from river valleys and alluvial deposits. england. _cornwall and devonshire._--none. _somersetshire._--hinton, larkhall, hartlip, st. audries, weston-super-mare, chedzoy, freshford. _gloucestershire._--gloucester, barnwood, beckford, stroud, tewkesbury. _dorsetshire._--bridport, portland fissure. _hampshire._--gale bay, newton. _wiltshire._--christian malford, fisherton, milford hill, near salisbury. _berkshire._--maidenhead, taplow, reading, hurley bottom. _oxfordshire._--yarnton, bed of the cherwell, city of oxford, wytham, culham. _essex._--lexden, orford, hedingham, lamarsh, isle of dogs, walton-on-the-naze, ilford (the finest specimen, see p. ), wenden, harwich, colchester, ballingdon, walthamstow. _hertfordshire._--camp's hill. _sussex._--bracklesham bay, brighton, lewes, valley of arun, pagham. _suffolk._--ipswich, hoxne. _norfolk._--bacton, cromer, yarmouth. _cambridge._--barrington, barnwell, chesterton, great shelford, barton, westwick hall. _huntingdonshire._--huntingdon, st. neots. _bedfordshire._--leighton buzzard. _middlesex._--at london, under various streets, etc., viz., st. james's square, pall mall, kensington, battersea, hammersmith, and, recently ( ), in endsleigh street. turnham green. in the bed of the thames at millbank, brentford, kew, acton, clapton, etc. kingsland. _surrey._--wellington, tooting, peckham, dorking, peasemarsh, near guildford. _kent._--crayford, erith, dartford, aylesford, hartlip, otterham, isle of sheppey, broughton fissure, medway, sittingbourne, newington, green street green, bromley, whitstable. _buckinghamshire._--fenny stratford. _northamptonshire._--oundle, kettering, northampton. _warwickshire._--rugby, wellesborne, lawford, bromwich hill, halston, newnam. _worcestershire._--stour valley, droitwich, banks of avon, fladbury, malvern. _leicestershire._--kirby park. _staffordshire._--copen hall, trentham. _cheshire._--northwich. _lincolnshire._--spalding. _yorkshire._--whitby, aldborough, gristhorpe bay, harswell, leeds, bielbecks, brandsburton, middleton, overton, alnwick, hornsea. _herefordshire._--kingsland. scotland. _ayrshire._--kilmaurs. between edinburgh and falkirk. chapel hall in lanarkshire, and bishopbriggs. at clifton hall. ireland. _cavan._--belturbet. _antrim._--corncastle. _waterford._--near whitechurch (but somewhat doubtful). . from caverns. _devonshire._--kent's cavern, oreston, beach cave, brixham. _somerset._--hutton cave, and a cave near wells, wookey hole, bleadon cave, box hill, near bath, durdham down, sandford hill. _kent._--in boughton cave, near maidstone. _nottinghamshire._--in church hole. _derbyshire._--in cresswell crags, robin hood cave, church hole. _glamorganshire._--in long hole, spritsail tor, paviland. _caermarthen._--in coygan cave. _waterford._--in shandon cave. appendix iv. literature. . popular works. _the story of the earth and man._ by sir wm. dawson. _the mammoth and the flood._ by sir henry howorth. _works by doctor gideon a. mantell_:-- _medals of creation._ _wonders of geology._ _petrifactions and their teaching._ _phases of animal life._ by r. lydekker. _science for all._ vols. (chapters on extinct animals.) _our earth and its story_, vol. ii. _winners in life's race._ by arabella buckley. _the autobiography of the earth._ by rev. h. n. hutchinson. _sea monsters unmasked._ by h. lee. . works of reference. _a manual of palæontology._ vols. by prof. alleyne nicholson, and r. lydekker. _the life-history of the earth._ by prof. alleyne nicholson. _origin of species._ by c. darwin. also _the journal of researches._ _the old red sandstone._ by hugh miller. _sketch book of popular geology._ by hugh miller. _early man in britain._ by prof. boyd dawkins. _the english encyclopedia._ (the vols. on natural history contain much information on extinct animals.) _the encyclopedia britannica._ ninth edition. _memoirs of the ichthyosauri and plesiosauri._ by thos. hawkins. phillips's _manual of geology_. new edition, by prof. h. g. seeley and r. etheridge. _the book of the great sea-dragons._ by thos. hawkins. _the geographical and geological distribution of animals._ by a. heilprin. _prehistoric europe._ by prof. james geikie. _palæontological memoirs._ by hugh falconer, m.d. _mammals, living and extinct._ by prof. flower and r. lydekker. _british fossil mammals and birds._ by sir r. owen. _a manual of palæontology._ by sir r. owen. _a catalogue of british fossil vertebrata._ by a. s. woodward and c. d. sherborn. . monographs. _the dinocerata._ by prof. o. c. marsh. _united states geological survey_, vol. x. washington, . _the odontornithes_, a monograph on the extinct toothed birds of north america. by prof. o. c. marsh. new haven, connecticut, . _the vertebrata of the tertiary formations._ by prof. e. d. cope. washington, . _the vertebrata of the cretaceous formations of the west._ by prof. e. d. cope. washington, . _contributions to the extinct vertebrate fauna of the western territories._ by joseph leidy. washington, . (the last three are in the reports of the _united states geological survey of the territories_.) _the british merostomata_ (palæontographical society). by dr. henry woodward, f.r.s. monographs by sir richard owen. _a history of british fossil reptiles._ vols. (cassell.) (most of which has been previously published in the _monographs of the palæontographical society_.) _on the megatherium, or giant ground sloth of america._ london, . _on the mylodon._ london, . _on the extinct wingless birds of new zealand._ london, . reprinted from _the transactions of the zoological society_. . journals. the student should consult the numerous papers by prof. marsh in _the american journal of science_; and by prof. cope in _the american naturalist_. many of prof. marsh's papers have also appeared in _the geological magazine_ and in _nature_. the two latter journals contain many other valuable papers (and reviews of monographs, etc.), too numerous to be separately mentioned. some are referred to in the text. _the quarterly journal of the geological society_ contains many papers on extinct animals. see also papers in _natural science_ and _knowledge_. appendix v. ichthyosaurs. [illustration: fig. .--_ichthyosaurus tenuirostris_, from würtemberg.] it was unfortunate that news of the highly interesting discovery at würtemberg came too late for our artist to make a new drawing for our first edition, to show the dorsal fin and large tail-fin, etc., described by dr. fraas.[ ] this has now been done, as shown in plate ii. by the courtesy of the proprietors of _natural science_, we are enabled to reproduce two drawings (fig. ) from the september number, illustrating a paper by mr. lydekker, in which he gives a _résumé_ of the latest intelligence with regard to ichthyosaurian reptiles. [ ] ueber einen neuen fund von _ichthyosaurus_ in würtemberg. _neues jahrbuch f. mineralogie_, , vol. ii. pp. - . the same author has published a valuable monograph, with beautiful plates, entitled _die ichthysaurier der süddentschen trias- und jura-ablagerungen_. to. tübingen, . in the present year ( ) there has been discovered in the lias of würtemberg the skeleton of an ichthyosaur, in which the outline of the fleshy parts is completely preserved (see lower figure). the reader will see from the figure that the tail-fin is very large, and the backbone appears to run into the lower lobe. such a tail-fin as this impression indicates must have resembled that of the shark's, only it is wider; but the shark's backbone runs into the _upper_ lobe. sir richard owen long ago foretold the existence of this appendage, and the discovery, coming now (when his life is despaired of), adds one more tribute to his genius. behind the triangular fin on the back comes a row of horny excrescences reminding us of those of the crested newt. as dr. fraas remarks, this discovery shows how closely analogous ichthyosaurs were in form to fishes, and further justifies the title of "fish-lizards." he considers that they did _not_ visit the shore. the reader will find much valuable matter in mr. lydekker's paper, above referred to. the following extract refers to the question of their reproduction: "it has long been known that certain large skeletons of ichthyosaurs from the upper lias of holzmaden, in würtemberg, and elsewhere, are found with the skeletons of one or more much smaller individuals enclosed partly or entirely within the cavity of the ribs [a specimen is figured]. of such skeletons there are four in the museum at stuttgart, two in that of tübingen, one at munich, and others in gent and paris. of these, two in stuttgart, as well as the two in tübingen, contain but a single young skeleton, while one of those at stuttgart has four, the munich specimen five, and the remaining stuttgart example upwards of seven young. some of these young and, presumably, foetal ichthyosaurs have the head turned towards the tail of the parent, while in others it is directed the other way. that these young have not been swallowed by the larger individuals within whose ribs they are found is pretty evident from several considerations. in the first place, their skeletons are always perfect. then they never exceed one particular size, and always belong to the same species as the parent. moreover, it would appear to be a physical impossibility for one ichthyosaur of the size of the stuttgart specimen to have had seven smaller ones of such dimensions in its stomach at one and the same time. we may accordingly take it for granted that these imprisoned skeletons were those of foetuses. it is, however, very remarkable, that, so far as we are aware, all the skeletons with foetuses belong to one single species; thus suggesting that this particular species was alone viviparous." it is to be hoped that further discoveries will be made, such as may finally settle this question. one would have expected that in some cases the young ones, if foetal, would be imperfectly developed. index. a Æpyornis. vid. moa-bird. agassiz, "age of reptiles," , ; "age of mammals," air, action of, allosaurus, ancients, ideas of the, , , , , apatosaurus, aqueous rocks, arbroath paving-stone, armadillo. vid. glyptodon. articulata, atlantosaurus, b backbone of fishes, "bad lands" of wyoming, baker, sir samuel, on crocodiles, ; on elephants, basalt, berossus, the chaldæan, birds, fossilisation of, ; ancestry of, , . vid. hesperornis, moa. blackie, prof. j. s., on ichthyosaurus, "breaks," , brontops, brontosaurus, ; vertebræ of, ; habits of, buckland, dean, , , , , - , , , buffon, , c cautley, captain, cave-earth, ceratosaurus, cetiosaurus, , _challenger_, h.m.s., chinese legends of mammoth, clidastes, , climate, of lias period, ; of eocene period, ; of tertiary era, collini, compsognathus, conybeare, rev., on plesiosaurus, , ; on sea-serpents, cope, prof. e. d., on sea-serpents, , , ; on eocene wingless bird, correlation, law of, , , , , crustaceans, cuvier, , , , , , ; on ichthyosaurus, ; on plesiosaurus, ; on iguanodon teeth, , ; on pterodactyls, , , ; on mosasaurus, , ; on tertiary animals, ; on megatherium, ; on mammoth, , ; on mastodon, d darwin, charles, ; on extinct sloths, dawkins, prof. boyd, ; on mammoth, de la beche, sir henry, , denudation, dimorphodon, dinocerata, ; skull and limbs of, ; where found, dinornis. vid. moa-bird. dinosaurs, chaps. v., vi., vii.; anatomy of, ; geographical range of, ; classification of, ; relations of, . vid. also allosaurus, atlantosaurus, brontosaurus, ceratosaurus, cetiosaurus, compsognathus, diplodocus, hadrosaurus, hoplosaurus, hylæosaurus, iguanodon, megalosaurus, morosaurus, ornithopsis, pelorosaurus, polacanthus, scelidosaurus, triceratops. diplodocus, dollo, m., draco volans, dragons, in mythology, ; flying dragons, ; legends of, e earth-drama, the, elephas ganesa, ; e. primigenius. vid. mammoth. eobasileus (cope), eocene period, , , eurypterus, evolution, of ichthyosaurs, ; of plesiosaurs, ; of dinosaurs, , ; of dinocerata, ; of sloths, explorations, in rocky mountains, by marsh, , ; in kansas, by cope, , ; in wyoming, by leidy, ; in uinta basin, by marsh, ; in sivalik hills, by falconer, ; in siberia, , f falconer, hugh, floods, destruction of animals by, flying dragons (pterodactyls), early discovery of, ; pterodactylus macronyx, ; p. crassrostris, ; p. spectabilis, ; differences between (pterodactyls) and birds, ; rhamphorhynchus, ; pterodactyls from the greensand, ; american pterodactyls, ; bones of ditto, ; habits of, footprints, of birds and reptiles, , ; of brontosaurus, ; iguanodon, ; supposed human footprints, forbes, mr. h. o., on moa-birds, fossils, how preserved, - ; changes in, g geikie, sir archibald, on scenery of a western plateau, "generalised types," geography of wealden period, ; of cretaceous period, , ; of eocene period, , , ; of miocene period, ; of pliocene period, giants, stories of, founded on discoveries of bones, , , - , , glyptodon, h hadrosaurus, harrison, mr. j., discovers scelidosaurus, hawkins, mr. t., his collection of fossil reptiles, ; his books, hoffman, home, sir everard, hoplosaurus, humboldt, huxley, on dinosaurus, , , , , ; on origin of birds, hylæosaurus, i ice age, or glacial period, , , ichthyornis, ichthyosaurus, ; scheüchzer on, ; droppings of, ; i. tenuirostris, , ; owen on habits of, ; eyes of, ; jaws of, ; vertebræ of, ; ancestry of, ; part played by, ; tail-fin, ; range of, ; sauranodon, ; toothless forms of, . vid. cuvier. iguana, teeth of, iguanodon, discovery of teeth, ; dr. wollaston, ; origin of name, ; jaws of, , ; food of, , ; discovery of belgian specimens, ; figure of skeleton, ; impressions of feet, ; thumb of, ; habits of, ; restoration by w. hawkins, ilia, imperfection of the record, impressions, of leaves, ; of cuttle-fishes, ; of jelly-fishes, ; of fish-lizards, and appendix v. irish elk, k king crabs, habits of, könig, l laramie beds, lariosaurus, legends. vid. giants. leidy, professor, leiodon, lias rocks, , , , , lyell, sir charles, on floods, ; on ideas of the ancients, ; on sudden destruction of fish-lizards, ; on tracks in connecticut sandstone, ; on mammoth, m mammals, evolution of, mammoth, distinct from living elephants, ; finding of, by adams, ; by benkendorf, ; how preserved, ; food of, ; extinction of, ; primitive drawing of, ; legends of, - mantell, dr. g. a., ; on "medals of creation," ; discovery of iguanodon, , ; on jaws and teeth of ditto, ; on wealden strata, ; discovery of hylæosaurus, ; on analogies of iguanodon and sloths, ; on discovery of mosasaurus, mantell, mr. walter, on moa-birds, - marsh, prof. o. c., on classification of dinosaurs, ; on brontosaurus, ; on atlantosaurus, ; his collection at yale college, ; on megalosaurus, ; on tracks of dinosaurs, etc., ; on ceratosaurus, ; on ancient vertebrate life in america, ; on reptiles and birds, ; on stegosaurus, , ; on triceratops, , ; his collection of pterodactyls, ; on sea-serpents, ; on dinocerata, , ; on explorations in the far west, , ; on footprints of mylodon, mastodon, ; bones and teeth first described, ; discovery of, by m. de longueil, ; exhibited as "the missouri leviathan," ; legends of, medals of creation. vid. mantell. megaceros. vid. irish elk. megalosaurus, ; localities of, ; teeth of, ; habits of, ; skeleton of, (fig. ) megatherium, ; habits of, miller, hugh, miocene period, , moa-birds, first discovery of, ; letter to prof. owen, ; w. mantell on, ; species of, ; native traditions of, ; Æpyornis, ; geographical distribution of giant birds, ; a new find of moas, monitors, morosaurus, mosasaurus, head, etc., found by hoffman, ; origin of name, ; head of, ; structure of, ; habits of, ; cuvier's opinion of, ; cope on sea-serpents, ; marsh's collection of ditto, museum at brussels, mylodon, , n neusticosaurus, new red sandstone period, ; tracks in new red sandstone, nodules, phosphatic, o old red sandstone, , omosaurus, ornithopoda, a group of dinosaurs, ornithopsis, ornithosauria, . vid. pterodactyls. owen, sir r., , , , ; on ichthyosaurus, , ; on plesiosaurus, , ; on dinosaurs, , ; on cetiosaurus, ; on megalosaurus, ; on iguanodon, ; on scelidosaurus, ; on pterodactyls, , ; on sea-serpents, ; on megatherium, ; on mammoth, - ; on mastodon, ; on dinornis, , p parish, sir woodbine, , pauw, m. de, peat, human bodies in, ; deer in, pelorosaurus, petrifactions, phillips, prof., on megalosaurus, plesiosaurus, origin of name, ; length of, ; skin, ; limbs, , ; habits, , ; relations, , . vid. buckland, conybeare, and könig. pliosaurus, , polacanthus, pterodactyls, c. kingsley on, ; origin of name, ; sizes of, ; first discovery of, ; structure of, , ; dimorphodon, ; p. spectabilis, ; condyle of, ; ramphorhynchus, ; specimens at yale college, u.s., ; range in time, ; whether warm-blooded, . vid. seeley, marsh, owen. pterygotus, pythonomorphs. vid. sea-serpents. r ramphorhynchus. vid. pterodactyls. record, imperfection of the, rhinoceros; tichorhine or woolly, ; legends founded on, rhytina, or "sea-cow," rocks, how made, - s sacrum, the, sauranodon. vid. ichthyosaurus. scelidosaurus, discovery of, scelidotherium, sclerotic plates, of ichthyosaurus, sea-cow. vid. rhytina. sea-scorpions, ; habits of, ; relations of, , , ; discovery of, ; "seraphim," ; woodward on, ; range in time of, sea-serpents, chap. ix. vid. mosasaurus, leiodon, clidastes. seeley, prof. h. g., on dinosaurs, , , ; on pterodactyls, sivalik hills, - sivatherium, - sloths. vid. megatherium, scelidotherium, mylodon. solenhofen limestone, or lithographic stone of bavaria, , , , specialisation, , stegosaurus, ; skeleton figured, ; restoration of, ; second brain, ; discovery of, , ; bony plates, steller's "sea-cow," vid. rhytina. st. fond, m. faujas, stonesfield slate, stratified rocks, table of, appendix i.; how formed, - stylonurus, sydenham, models of extinct animals at crystal palace, t theropoda, tinoceras, , triceratops, ; teeth of, ; skull, ; spines, etc., ; extinction of, trilobites, u uintatherium, uniformity, v vegetation of jurassic period, ; of wealden period, ; of eocene period in america, von meyer, on dinosaurs, w water, action of, on organic matter, , ; on fossils, waterhouse hawkins, , wealden strata, , , williams, mr. r., on great irish deer, wings, of pterodactyls, , , , ; of moa-bird, woodward, dr. henry, , , , workmen (in pits and quarries), carelessness of, , , printed by william clowes and sons, limited, london and beccles. _recently published, by the same author. price s._ the story of the hills. _a popular account of mountains and how they were made._ by the rev. h. n. hutchinson, b.a., f.g.s., author of "the autobiography of the earth." _opinions of the press._ "this work belongs to that useful class whose intention is to arouse interest in the works of nature, and quicken the faculty of observation." _manchester guardian._ "it tells in the pleasantest way the first things that geologists learn and teach crabbedly about the heaving up of hills, the wearing of them down by the weather, the breaking out of volcanoes, and kindred matters."--_scotsman._ "the author is a man of wide geological and physiographical reading, possessed of the gift of clearly interpreting the writers he reads, and of reproducing their facts and conclusions in easily understood and even attractive language."--_science gossip._ "it will be read with pleasure and profit by the tourist who likes to know just enough about the sundry points of interest connected with the scene of his wanderings to make the enjoyment of his outing intelligent."--_nature._ "mr. hutchinson's book deals with the slow moulding of mountain forms by streams and by weathering, and with the forces by which mountains have been upheaved, and will double the pleasure of a mountain trip. it is of a handy and portable size, and is illustrated with several excellent reproductions of photographs by the late mr. w. donkin."--_knowledge._ "a charmingly written and beautifully illustrated account of the making of the mountains. an admirable gift book."--_yorkshire post._ "this is a popular and well illustrated account of mountains and how they were made. the illustrations are especially excellent, being reproductions of photographs taken by the late mr. w. donkin, messrs. walentine and sons (dundee), and mr. wilson (aberdeen). mr. hutchinson writes interestingly, and evidently knows geology and physiography."--_journal of education._ seeley and co., limited, essex street, strand. _recently published, by the same author_ the autobiography of the earth. _a popular account of geological history._ by the rev. h. n. hutchinson, b.a., f.g.s. _crown vo, cloth, with illustrations, price s. d._ contents.-- . cloud-land, or nebular beginnings-- . the key to geology-- . an archaic era-- . cambrian slates-- . the slates and ashes of siluria-- . the old red sandstone-- . the mountain limestone-- . forests of the coal-period-- . a great interval-- . the cheshire sandstones-- . new phases of life-- . bath oolites-- . an age of reptiles-- . the chalk downs-- . the new era-- . the ice-age and advent of man. _some opinions of the press._ "his sketch of historic geology has a genuine continuity. it is so written as to be understanded of plain people, and is illustrated by some very good woodcuts and diagrams."--_saturday review._ "this most interesting book."--_spectator._ "a delightfully written and thoroughly accurate popular work on geology, well calculated to engage the interest of readers in the fascinating study of the stony science."--_science gossip._ "in this work the rev. h. n. hutchinson produces a popular account of geological history, and explains the principles and methods by which that history has been read. he endeavours to interpret the past by the light of the present, first acquiring a knowledge, by direct observation and self-instruction, of the chief operations now taking place on the earth's surface, and then employing this knowledge to ascertain the meaning of the record of stratified rocks. this principle of 'uniformity' knocked the old teaching of catastrophism on the head. the author is accurate in all his details, yet his subject is touched into something not at all unlike romance. the illustrations are good."--_national observer._ london: edward stanford, & , cockspur street, s.w. * * * * * transcriber's note spelling and hyphenation was standardized. all oe and oe ligatures were converted to "oe" and "oe" respectively. the word garuda has a macron over the u in the printed version. missing endquote from the quoted passage, beginning in the last paragraph on page , was confirmed by consulting mantell's "the medals of creation" (p. ). the wonder book of volcanoes and earthquakes [illustration: mount vesuvius in eruption] the wonder book of volcanoes and earthquakes by professor edwin j. houston, ph.d. new york frederick a. stokes company publishers copyright, , by frederick a. stokes company _all rights reserved_ _october, _ acknowledgments we take this opportunity of acknowledging the courtesy of the following publishers, who have helped us in connection with the illustrations of this book:-- henry holt and company ("physiography," by rollin d. salisbury). d. appleton and company (figs. , , , , , , , , and , "volcanoes: what they are and what they teach," by j. w. judd; fig. , "principles of geology," by sir c. lyell). the american book company ("manual of geology," by james dwight dana). g. p. putnam's sons ("earthquakes in the light of the new seismology," by c. e. dutton). the clarendon press ("geology: chemical, physical, and stratigraphical," by joseph prestwich). the publishers. contents chapter page i. the volcanic eruption of krakatoa in ii. some effects of the eruption of krakatoa iii. the volcanic island of hawaii iv. the volcanic island of iceland v. vesuvius vi. other volcanoes of the mediterranean vii. orizaba, popocatepetl, ixtaccihuatl, and other volcanoes of mexico viii. coseguina and other volcanoes of central america ix. the volcanic mountains of south america x. volcanoes of the united states xi. the catastrophe of martinique and the volcanic islands of the lesser antilles xii. some other noted volcanic mountains xiii. jorullo, a young volcanic mountain xiv. mid-ocean volcanic islands xv. submarine volcanoes xvi. distribution of the earth's volcanoes xvii. volcanoes of the geological past xviii. laplace's nebular hypothesis xix. the earth's heated interior, the cause of volcanoes xx. some forms of lava xxi. mud volcanoes and hot springs xxii. the volcanoes of the moon xxiii. earthquakes xxiv. some of the phenomena of earthquakes xxv. the earthquake of calabria in xxvi. the great lisbon earthquake of xxvii. the earthquake of cutch, india, in xxviii. the san francisco earthquake of april , xxix. some other notable earthquakes xxx. sodom and gomorrah and the cities of the plain xxxi. instruments for recording and measuring earthquake shocks xxxii. seaquakes xxxiii. the distribution of earthquakes xxxiv. the causes of earthquakes xxxv. earthquakes of the geological past--cataclysms xxxvi. the kimberly diamond fields and their volcanic origin xxxvii. the fabled continent of atlantis xxxviii. plato's account of atlantis xxxix. nature's warning of coming earthquakes full page illustrations page mt. vesuvius in eruption frontispiece stones and lava thrown upwards--eruption of mokuaweoweo, hawaii, july - , fac. cotopaxi the lava flow of the crater of kilauea, hawaiian islands a san francisco pavement torn by the earthquake illustrations in text fig. page . the sunda islands . krakatoa before the eruption . krakatoa after the eruption . volcanic dust as it appears under the microscope . the hawaiian islands . hawaii . panorama of mokuaweoweo . view of the crater of kilauea from the volcano house . crater of kilauea . sections of kilauea at different periods . iceland . the mediterranean . the volcanic district around vesuvius . mt. etna . stromboli, viewed from the northwest, april, . mexico and central america . south america . the united states . panorama from the mesa at the edge of mt. taylor . volcanic necks, edge of mesa at mt. taylor . the lesser antilles . graham's island--a recent volcanic island . aleutian islands . map of the world, showing location of active and recently extinct volcanoes . volcanic vesicles . thread-lace scoriÆ from kilauea . thread-lace scoriÆ from kilauea . frost-like lava crystals . frost-like lava crystals . basaltic columns, isle of cyclops, italy . columnar and non-columnar basalt , . driblet cones . lava stalactites . crater of the great geyser of iceland . giant geyser . bee hive . bee hive geyser of iceland . heavy stone obelisks twisted by calabrian earthquake of . circular hollow formed by calabrian earthquake . section of circular hollow formed by calabrian earthquake . map of the calabrian earthquake of . fissures caused by the calabrian earthquake . map showing district visited by the earthquake of cutch of . sindree before the earthquake of . sindree after the earthquake of . map of western coast of california showing position of san francisco . new zealand . map showing region affected by the charleston earthquake of . syria . complex record of seismograph . long distance seismogram . vicentini vertical pendulum . vicentini pendulum and recorder . davison's earthquake map of japan the wonder book of volcanoes and earthquakes the wonder book of volcanoes and earthquakes chapter i the volcanic eruption of krakatoa in krakatoa is a little island in the straits of sunda, about thirty miles west of the island of java, and nearly the same distance east of the island of sumatra. it is uninhabited and very small, measuring about five miles in length and less than three miles in width. its total area is only thirteen square miles. this little piece of land made itself famous by what took place on it during the month of august, . krakatoa is one of the many islands that form the large island chain known as the sunda islands. the most important islands of this chain are sumatra, java, sumbawa, flores, and ceram. between sumatra and java, the largest two of these islands, there is a channel called the straits of sunda that connects the waters of the indian ocean with those of the pacific ocean. the straits of sunda is an important piece of water that forms one of the great highways to the east. shipping is, therefore, always to be found in its waters. as can be seen by the map, krakatoa is not far from the equator, being situated in lat. ° ' s. and long. ° ' e. from greenwich. since there are about sixty-nine miles in every degree of latitude, krakatoa is about miles south of the equator, and is about twenty-five miles from java. java is part of the dutch east indies, which includes java, celebes, the spice islands, and parts of borneo and sumatra. batavia, the principal seaport of java, near the northwest coast, is a great shipping centre, visited by vessels from nearly all parts of the world. it has, however, no harbor, but is approached from the ocean by means of a canal two miles in length, the sides of which are provided with massive brick walls. besides batavia, which is situated about one hundred english miles east of krakatoa, there are many smaller towns or villages, the most important of which is anjer, a thriving seaport town, where sailing vessels obtain their supplies of food and fresh water. before the eruption of krakatoa, anjer was provided with a strong, stone lighthouse. java is especially noted for its production of coffee, in which it is second only to brazil. its area is about the same as that of the state of new york. java is one of the most densely populated parts of the world, containing nearly four times as many people as the whole state of new york. these facts about the situation and surroundings of krakatoa are necessary to an understanding of the wonderful thing that happened on it during the month of august, . in that month krakatoa suffered a most tremendous explosive volcanic eruption, for it is a volcano. [illustration: fig. . the sunda islands] a volcano is a mountain or hill, generally conical in shape, having at the top a nearly central opening, called a _crater_, from which at times melted rock and lava, vapor and gases escape. the lava either flows down the side of the mountain in a liquid condition, or is thrown upwards into the air. if the distance the lava is thrown upwards is sufficiently great the melted matter solidifies before it falls to the earth. in such cases the largest fragments form what are called _volcanic cinders_, the smaller pieces, _volcanic ashes_, and the extremely small particles, _volcanic dust_. if, however, the lava is thrown to a comparatively small height, it is still melted when it falls, and is then known as _volcanic drops_ or _driblets_. [illustration: fig. . krakatoa before the eruption] it is not surprising that krakatoa is a volcanic island, since it lies in one of the most active belts of volcanic islands in the world, and near the coasts of the most active of these islands; i. e., java. this belt, as shown in the map, includes, besides the sunda island chain, parts of gilolo, celebes, mindanao and the philippine islands. these islands lie between asia on the northwest and australia on the southeast. [illustration: fig. . krakatoa after the eruption] there is no other part of the world with, perhaps, the single exception of japan, where so many active volcanoes are crowded in so small a space. the island of java, small as it is, has nearly fifty volcanoes, of which at least twenty-eight are active. they are situated in a lofty range running from east to west, some of the peaks of which are more than , feet above the level of the sea. volcanic eruptions are so frequent that the island is seldom free from them. as will be seen from the map shown in fig. , krakatoa consists of three groups of volcanic mountains, the southern group giving the name of krakatoa to the island. strictly speaking, this mountain was called _rakata_, but as it is now generally known as krakatoa, it would be unwise to attempt to call it by any other name. the central mountain or group of mountains is known as danan, and consists largely of part of an old crater. the group of mountains which lies near the northern end of the island was known as perboawatan. from the centre of this latter group of mountains are several old lava streams consisting of a variety of lava resembling a dark-colored glass, known to mineralogists as _obsidian_, or _volcanic glass_. although krakatoa was always a volcano, yet between the years and , it was in the condition of a sleeping or extinct volcano. there had been a severe explosive eruption in the year , that caused great loss of life and property, but ever since that time all activity had ceased and it seemed that the volcano would never again burst out. in other words, it was generally regarded as a trustworthy, sedate, quiet, inoffensive and perfectly safe volcano, that had become extinct. the long continued quiet of krakatoa was broken on the th of may, , when the inhabitants of batavia on the island of java were terrified by noises like the firing of great guns, that were first heard between ten and eleven o'clock in the morning. these noises were accompanied by the shaking of the ground and buildings. the sleeping volcano of krakatoa was evidently growing restless, but no great damage was done and soon all was again quiet. the disturbances were merely the forerunner of the terrible eruption soon to follow, and confidence was soon restored. but suddenly, on sunday, august th, , almost without any further warnings, krakatoa burst into terrible activity and began an explosive eruption that has never been equalled in severity in the memory of man. that memorable sunday of august th, , came during a season of the year known as the _dry monsoon_, a name given the season of the periodical winds from the indian ocean. batavia, and the surrounding country, greatly needed rain, for in this part of the world it seldom rains from april to october, although the air is very moist and damp. for this reason the beginning of the wet season is always welcomed. when, therefore, the rumbling sounds of the approaching catastrophe of krakatoa were heard in batavia, the people, believing that the noises were due to peals of thunder, rejoiced, for all thought they heralded an earlier setting in of the wet monsoon. but when the rumbling sounds increased and reports were heard like heavy artillery, it was clear that the sounds were the beginning of a volcanic eruption, a phenomenon with which they were only too well acquainted, but, as volcanic eruptions were far from being uncommon in java, no one was very greatly frightened. but this time the noises increased to such an extent that the people became alarmed. throughout the night the appalling sounds continued and were accompanied by shakings of the earth sufficiently strong to shake the houses violently. sleep was out of the question. many of the people left their houses and remained all night in the open air, fearing the shocks would bring the houses down over their heads. the morning instead of heralding the dawn of a beautiful tropical day, with its bright, cheerful sunlight, brought with it skies covered with gray clouds that completely hid the sun. the rumbling sounds, however, had decreased, and the people were beginning to congratulate themselves that the dangers were over, when suddenly, the sky grew darker, and there began a shower of ashes that soon covered the streets and houses of the city. about seven o'clock on the morning of august th, a most tremendous crash was heard. the sky rapidly became so dark that it was soon necessary to light the lamps in the houses of batavia, and some of the neighboring towns in the western part of java. in addition to this the air was filled with vapor, while every now and then earthquake shocks were again felt. these shocks were accompanied by terrific noises like those produced by the explosion of heavy artillery. the noises rapidly increased in number and intensity until they produced a nearly continuous roar, the nature of which it is almost impossible to describe since it is probable that such sounds had never been heard before by man. it is a curious fact, which, i believe, has never been satisfactorily explained, that in most cases the people in the immediate neighborhood of the volcano, as, for example, those on board vessels in the straits of sunda, did not hear the terrific noises at all. possibly they were too loud and simply gave a single inward impetus to the drum of the ear and then held it in position. probably some of my readers may remember that witty description given by dr. oliver wendell holmes of an alleged effort made by all the people of the world to find out whether or not there is a man in the moon. this wonderful plan was as follows: careful calculations were made to ascertain when it would be the same time over all the earth so that all the people of the earth could simultaneously shout at the top of their voices. in this way it was hoped that the man in the moon, if there were such a person, would notice the noise. the story goes on to tell how when the time approached for the great experiment, and all were ready to shout as loud as they could, that each person reasoning to himself or herself, that amid so great a noise no one could notice whether his or her voice was omitted, determined to remain silent, so as to be able to hear the noise and the better to observe what the man in the moon would do when the sound reached him. the result was that every person on the earth remained silent and simply listened, so that the earth was never so quiet before. had oliver wendell holmes, or any other person conceiving the witty idea, lived during the time of the great explosive eruption of krakatoa, on that memorable august th, , he might have taken the opportunity of observing the man in the moon, had he not been frightened by what was occurring, for certainly never before were such tremendous or terrifying sounds produced, for these sounds, as we shall see shortly, were actually heard for distances of more than , miles from the volcano. there were two different kinds of waves produced in the air by the tremendous forces at work in the eruption of krakatoa; namely, atmospheric waves and sound waves. the atmospheric waves showed their presence in the air by means of changes produced in the atmospheric pressure. now, while these changes cannot readily be felt by man, yet their presence can be easily shown by the use of instruments called _barometers_. there are in different parts of the world, buildings called _meteorological observatories_, that are provided, among other instruments, with recording barometers. these instruments caught the great atmospheric waves that were produced by the eruption of krakatoa. in this manner, the astounding fact was learned that the waves starting from the volcano travelled no less than seven times around the world. when we say astounding, it must not be understood that the formation of such waves was at all contrary to the known laws of physics. on the contrary, provided the force of the eruption was sufficiently great, such waves must have been produced in the great ærial ocean. the astonishing, or wonderful thing, was that the force setting up these waves was so great that it caused them to move seven times around the globe. the atmospheric waves were so powerful that it will be worth our while to describe them in detail. starting from the volcano of krakatoa, as a centre, these waves moved outwards in all directions, becoming gradually larger and larger until they reached a point halfway round the globe, or ° from krakatoa. the waves did not, however, stop here, but continued moving onward, now growing smaller and smaller until they reached a point in north america, immediately opposite krakatoa. such a point on a globe is called an _antipodal point_.[ ] the waves did not stop at this point, but again advanced moving toward krakatoa, growing larger and larger until they again reached a point halfway around the globe, or ° from krakatoa, when they again continued moving but now continually growing smaller and smaller, until they reached krakatoa. here they again began moving completely around the globe, and this was continued for as many as seven times. it must not be supposed that the waves ceased on the seventh time around. on the contrary, they, probably, kept on moving for many additional times, but they were then so feeble that even the sensitive recording barometers were unable to detect their presence. there was another kind of waves in the atmosphere that did not require barometers for their detection. these were the sound waves, and can readily be detected by the human ear. now, in the case of the great eruption of krakatoa, the intensity of the sounds was so great that the sounds could be heard distinctly at distances of several thousand miles from krakatoa. the sound waves so closely resembled the explosion of artillery that at acheen, a port on the northern coast of sumatra, , miles from krakatoa, the authorities, believing that an attack was being made on the port, placed all their troops under arms to repel the invaders. the sounds were also distinctly heard at bangkok, in siam, a distance of , miles from the volcano. they were also heard at the chagos islands, a group of islands situated in the indian ocean about , miles from krakatoa. two steamers at singapore, miles distant, were despatched to find the vessel that was believed to be firing guns as distress signals. the sounds were distinctly heard in parts of south australia, , miles distant, and in western australia, at , miles distance. but it will be unnecessary to give any further details of the great distances at which these sounds were actually heard. it will suffice to say that they were heard as far off as about , miles. it is difficult to picture to one's self such great distances. assuming the greatest distances to be in the neighborhood of , miles, it would be as if a sound produced, say, in boston, new york, or philadelphia, was so loud that it could be heard in amsterdam, london, or paris. some idea of the intensity of these sounds can be had from the fact that in batavia, when, in accordance with usage, a gun was fired from one of the forts at eight o'clock in the morning, two hours before the greatest intensity of the sounds had been reached, the sound of the gun could scarcely be heard above the continuous roar. while, of course, the principal reason the sound waves were carried so far was the great force causing the eruption, yet these distances were increased by the fact that the explosion occurred in a region almost entirely surrounded by great bodies of water. the waves could, therefore, be readily carried along the surface of the sea. had there been a high mountain wall, like the andes of south america, on one side of the volcano they would probably have been shut off in this direction a short distance from where they were produced. chapter ii some effects of the eruption of krakatoa besides the sound waves in the air, there were waves in the waters of the ocean. suddenly, without any warning, the people of batavia were surprised by a huge wave that, crossing the straits of sunda, entered the ship canal before referred to as connecting the city with the ocean, and, rising above the brick wall, poured over the surrounding country. although batavia was english miles from krakatoa, yet after travelling this distance the wave was sufficiently strong to enter the city and flood its streets with water to a depth of several feet. fortunately, the loss of life was small in the city of batavia, but very great in the surrounding towns and villages. the ocean waves varied in height at different times of the eruption. the greatest were from fifty to eighty feet high. just imagine the effect of a wave twice the height of an ordinary house. the waves caused great damage to the shipping in the neighborhood. in one instance, a vessel was carried one and a half miles inland and left on dry land thirty feet above the level of the sea. the total loss of life by the waves has been estimated at , people; besides this, of course, there was a great amount of property destroyed. the greatest loss was in the immediate neighborhood of krakatoa. gigantic waves swept over the lowlands lying near the shores of sumatra and java, where over areas several miles in width nearly everything was destroyed, the houses, trees, and people being swept away and the surface of the land greatly changed. the towns of karang and anjer, as well as numerous smaller villages, were almost completely destroyed. the seaport town of anjer, by far the most important of the above towns, was almost completely swept away. the heavy stone lighthouse was so completely obliterated that no traces of its heavy stone foundations could afterwards be found. the rev. phillip neale, formerly a british chaplain at batavia, from whose account of the eruption of krakatoa some of the above facts have been taken, tells of the brave action of the keeper of the lighthouse at anjer. besides his work as lighthouse keeper, to see that the light was constantly burning during the night, he was charged with telegraphing to batavia the names of all passing vessels. on the fateful morning of the great catastrophe, observing that the sun did not rise, he kept the light of the lighthouse burning, and, notwithstanding the danger to which he was exposed, continued at his post in order to send word to batavia of the passing of an english steamer. while doing this the lighthouse was swept away and the brave man perished. the following verbal account of the destruction of the port of anjer was given by a dutch pilot stationed at anjer. this description is quoted by the rev. mr. neale from an article prepared by him for publication in "the leisure hour." "i have lived in anjer all my life, and little thought the old town would have been destroyed in the way it has. i am getting on in years, and quite expected to have laid my bones in the little cemetery near the shore, but not even that has escaped and some of the bodies have actually been washed out of their graves and carried out to sea. the whole town has been swept away, and i have lost everything except my life. the wonder is that i escaped at all. i can never be too thankful for such a miraculous escape as i had. "the eruption began on the sunday afternoon. we did not take much notice at first, until the reports grew very loud. then we noticed that krakatoa was completely enveloped in smoke. afterwards came on the thick darkness, so black and intense that i could not see my hand before my eyes. it was about this time that a message came from batavia inquiring as to explosive shocks, and the last telegram sent off from us was telling you about the darkness and smoke. towards night everything became worse. the reports became deafening, the natives cowered down panic-stricken, and a red, fiery glare was visible in the sky above the burning mountain. although krakatoa was twenty-five miles away, the concussion and vibration from the constantly repeated shocks were most terrifying. many of the houses shook so much that we feared every minute would bring them down. there was little sleep for any of us that dreadful night. before daybreak on monday, on going out of doors, i found the shower of ashes had commenced, and this gradually increased in force until at length large pieces of pumice stone kept falling around. about six a. m. i was walking along the beach. there was no sign of the sun, as usual, and the sky had a dull, depressing look. some of the darkness of the previous day had cleared off, but it was not very light even then. looking out to sea i noticed a dark, black object through the gloom, travelling towards the shore. "at first sight it seemed like a low range of hills rising out of the water, but i knew there was nothing of the kind in that part of the sunda strait. a second glance--and a very hurried one it was--convinced me that it was a lofty ridge of water many feet high, and worse still, that it would soon break upon the coast near the town. there was no time to give any warning, and so i turned and ran for my life. my running days have long gone by, but you may be sure that i did my best. in a few minutes i heard the water with a loud roar break upon the shore. everything was engulfed. another glance around showed the houses being swept away and the trees thrown down on every side. breathless and exhausted i still pressed on. as i heard the rushing waters behind me, i knew that it was a race for life. struggling on, a few yards more brought me to some rising ground, and here the torrent of water overtook me. i gave up all for lost, as i saw with dismay how high the wave still was. i was soon taken off my feet and borne inland by the force of the resistless mass. i remember nothing more until a violent blow aroused me. some hard, firm substance seemed within my reach, and clutching it, i found i had gained a place of safety. the waters swept past, and i found myself clinging to a cocoanut palm-tree. most of the trees near the town were uprooted and thrown down for miles, but this one fortunately had escaped and myself with it. "the huge wave rolled on, gradually decreasing in height and strength until the mountain slopes at the back of anjer were reached, and then, its fury spent, the water gradually receded and flowed back into the sea. the sight of those receding waters haunts me still. as i clung to the palm-tree, wet and exhausted, there floated past the dead bodies of many a friend and neighbor. only a mere handful of the population escaped. houses and streets were completely destroyed, and scarcely a trace remains of where the once busy, thriving town originally stood. unless you go yourself to see the ruin you will never believe how completely the place has been swept away. dead bodies, fallen trees, wrecked houses, an immense muddy morass and great pools of water, are all that is left of the town where my life has been spent. my home and all my belongings of course perished--even the clothes i am wearing are borrowed--but i am thankful enough to have escaped with my life and to be none the worse for all that i have passed through." as is common in cases of earthquake waves a great depression in the level of the sea occurred at places great distances from krakatoa. for example, at the harbor of ceylon, the water receded so far that for about three minutes the boats were left high and dry, and then a huge wave carried them with it as it rushed over the land. perhaps one of the best evidences of the immense power of ocean waves is to be seen in the massive blocks of white coral rock that were washed up by the waves, on parts of the coast of java for distances of from two to three miles from the ocean. many of these blocks weighed from twenty to thirty tons. indeed, some of them reached the weight of from forty to fifty tons. it is probable that the island of krakatoa and its neighboring smaller islands formed portions of a huge cone about eight miles in diameter, that has been broken up at some very remote but unknown time by, perhaps, a greater catastrophe than that of august, . in the straits of sunda the water was raised fifty feet to eighty feet above the ordinary level, and produced tremendous destruction especially on the coasts of java and sumatra, sweeping away many villages and drowning many thousands of people. the wave had a velocity of progression of nearly miles per hour, or eight times faster than an ordinary express train. when it is said that the _velocity of progression of the wave_ was nearly miles per hour, it is not meant that a body floating on the ocean, such, for example, as a ship, would have been carried forward at this high velocity, but would merely rise and fall in a to-and-fro swing to about the height of the wave; that is, fifty to eighty feet according to what may have been the height. as in the case of the sound waves these motions of water covered or passed over nearly all the waters of the earth. the waves progressing toward the west, crossed the indian ocean reaching to the coast of hindostan, and madagascar, and sweeping around the southern part of africa, finally reached the coasts of france and england, as well as the eastern part of north and south america. sweeping towards the east, they reached the coasts of australia, new zealand, and crossing the vast pacific ocean were felt at alaska and the western coasts of north and south america. but besides the enormous waves caused by the eruption, there were marked changes in the level of the land. large portions of the coast of sumatra and java were almost annihilated, much of the original surface near the coast being submerged, and places that were formerly dry land are now covered with water to a depth of from to feet. the enormous amount of material thrown into the air by the forces of the eruption is especially characteristic of this phenomenon. such quantities of pumice stone and ashes fell from the clouds that, sinking in the water and collecting on the bed of the channel, they changed the depth of the water, so as to render navigation dangerous. indeed, the sebesi channel, lying on the north of the island of krakatoa was completely blocked by a huge bank of volcanic material, portions of which projected above the water, forming two smaller islands. these, however, have since been washed away by the waves. we will not attempt to give at present any explanations as to the causes of this great volcanic eruption, since the different theories as to the cause of volcanoes will be better understood when other volcanic eruptions have been described. it is sufficient here to say that if a large quantity of water should have suddenly reached a great mass of molten rock, frightful explosive eruptions would have occurred, and if the island was resting on a submerged crater its sudden disappearance may be explained. another great wonder connected with the explosive eruption of krakatoa was the enormous heights to which the fine dust was thrown up into the air. it has been asserted that during the most intense of these eruptions the particles reached elevations of perhaps more than twenty-five miles above the level of the sea. carried by the winds, the fine particles remained suspended in the air for many months, and gave rise to magnificent sunlight effects, such as early dawn, lengthened twilights, lurid skies, and gorgeous sunsets of a reddish tint. there were also caused curious haloes, as well as green and blue moons. the fine dust particles consisted of minute crystals of feldspar and other minerals, and when examined under the microscope presented the appearance shown in fig. . these mineral substances permitted a portion of the light to pass through them, thus producing wonderful optical effects in the atmosphere either because they acted like minute prisms and so produced rainbow colors, or because they turned the rays of light out of their course as to produce what is called interference by color effects of a nature similar to the colors seen in mother-of-pearl, rainbow coal, or in the wing cases of many beetles. the explanations of these phenomena are too difficult for a book of this character. an explosive volcanic eruption is a very terrifying and wonderful phenomenon. frightful roaring sounds are suddenly heard, the earth shakes for many miles around, when suddenly a vast quantity of molten rock, and sometimes huge stones, are thrown out of the crater high up into the air. so great is the force that throws these materials out of the opening that heavy masses of rocks often are ejected very much faster than the projectiles from the largest guns that are used in any of the navies of the world. [illustration: fig. . volcanic dust as it appears under the microscope] as the molten lava cools and falls in the form of prodigious clouds of ashes, cinders and dust, for many miles around the volcano, even the light of the sun is obscured, and one cannot see the hand before the face. some of the materials in these clouds are so light that they remain suspended in the air for many hours, often indeed for many days, and sometimes even for years. the heavier particles, however, soon begin to fall, and before long the earth's surface both around the volcano, and often at considerable distances from it, is covered with a thick layer of ashes. the sounds accompanying a volcanic eruption are often terrifying. amid shakings and tremblings of the earth's crust, known as earthquakes, there are occasionally heard noises like the explosion of huge guns. sometimes these sounds follow one another so rapidly that they produce an almost continuous roar. through the roar of the explosion a curious crackling noise can be heard, due to the fragments of stone hurled out of the crater striking against one another, especially as the stones which are thrown out of the crater and have commenced to fall back again to the earth, are struck by others that are still rising. immense quantities of ashes, stones, vapor and gases are thrown upwards for great distances into the air, while, at the same time, a lava stream pours over the lowest side of the crater. as the column of ashes and cinders reaches its greatest height in the air, it begins to spread outward on all sides, rapidly growing like a huge dark mushroom. this soon shuts out the light of the sun, and from it showers of red hot ashes and cinders fall to the earth. it would be extremely dangerous to be on the side of the volcanic mountain during an explosive eruption; for, even should you escape falling into an opening in the side of the mountain, you might be killed by the huge stones that are constantly falling on all sides around the opening, or might be buried under the vast showers of red hot ashes that are poured down from the dense clouds overhanging the mountain, or suffocated by clouds of sulphur vapor that rush down its sides. when at a safe distance the sight is certainly magnificent. there is no light from the sun. all would be in pitch darkness but for the reddish glare thrown upwards by the red hot lava, by the glowing showers of ashes that are being rained down on the sides of the mountain, or by terrific lightning flashes, due to the discharge of the immense quantities of electricity produced by the forces of the eruption. naturally a great volcanic eruption can cause a considerable loss of life and property. when a large lava stream begins to flow down the sides of the mountain, it cannot be stopped, and should it flow toward a village or town it is likely to destroy the town completely. besides this, the vegetation of the country for many miles around is destroyed by the showers of red hot ashes that fall from the sky. the houses of neighboring cities are similarly ruined by the great conflagrations thus set up. further destruction is also caused by large streams of mud that rush down the slopes of the mountain, or by huge waves set up in the ocean. if the volcano is situated, as most volcanoes are, near the coast, the showers of ashes and falling stones may set fire to vessels in the neighborhood, or the progress of such vessels may be seriously retarded by layers of ashes or pumice stone that float on the surface. sometimes these layers are so thick as actually to bring ships to a complete standstill. it must not be supposed that volcanoes are in a constant state of eruption. on the contrary, nearly all volcanoes, after an eruption, become _quiet_ or _inactive_. the air soon clears by the ashes settling, and the sunlight again appears. a crust forms over the surface of the lava, which rapidly becomes hard enough to permit one to walk over it safely. the vegetation, which has been destroyed by the hot ashes, again springs up, and, if the volcano happens to be situated within the tropics, where there is an abundance of moisture, the land soon again becomes covered by a luxuriant vegetation. most of the people, who have escaped sudden death during the eruption, return to the ruins of their houses; for it is a curious fact that no matter how great has been a volcanic eruption, or how far-reaching the ruin, the survivors, as a rule, do not appear to hesitate to return to their old neighborhood. in a few years the fields are re-cultivated, the villages are rebuilt, and the people apparently forget they are living over a slumbering volcano, which may at any time again burst forth in a dangerous eruption. a volcano that throws out molten rock, vapor and gases is known as an _active volcano_. an active volcano, however, is only correctly said to be in a state of eruption when the quantity of the molten rock, lava or vapor it throws out is greatly in excess of the ordinary amount. sometimes the volcanic activity so greatly decreases that the molten rock or lava no longer rises in the crater, but, on the contrary, begins to sink, so that the top of the lava in the crater is often at a considerable distance below its edges. the lava then begins to harden on the surface, and, if the time is sufficient, the hardened part extends for a considerable distance downward. in this way the opening connecting the crater with the molten lava below becomes gradually closed, the volcano being thus shut up, or corked, just as a bottle is tightly closed by means of a cork driven into the opening at its top so as to prevent the escape of the liquid it contains. it may sound queer to say that a volcano has its crater so corked up as to prevent the escape of the lava, but the idea is nevertheless correct and helpful. to realize the size of these huge volcanic corks one must remember that the craters of some volcanoes are several miles across. a volcano thus choked or corked up is said to be _extinct_. when we speak of an extinct volcano we do not mean that the volcano will never again become active. a volcano does not cease to erupt because there are no more molten materials in the earth to escape, but simply because its cork or crust of hardened lava has been driven in so tightly that the chances of its ever being loosened again seem to be very small. but small as the chances may seem we must not forget that the volcano may at any time become active, or go into its old business of throwing out materials through its crater. a volcano in an extinct condition is not unlike a steam boiler, the safety valve of which has been firmly fixed in place. if the steam continues to be generated in the boiler, it is only a matter of time when the boiler will blow up, and the explosion will be all the greater because the safety valve did not allow the steam to escape earlier. sometimes an intermediate class of volcanoes called _dormant_ is introduced between active volcanoes on the one hand and extinct volcanoes on the other. the name dormant volcano, or, as the word means, _sleeping volcano_, is objectionable, since it might lead one to think that an extinct volcano is not sleeping but dead, and this is wrong. since the plug of hardened lava in the volcanic crater is generally at a much lower level than the top of the crater, the crater will soon become filled to a greater or less depth with water, produced either by the rain, or by the melting of the snow that falls on the top of the mountain. crater lakes, often of very great depths, are common in extinct volcanoes. of course, when an extinct volcano again becomes active, two things must happen if the eruption is explosive. in the first place, the force of the explosion must be sufficiently great to loosen the stopper or plug of hardened lava which stops it. in doing this the mass is broken into a number of fragments that are thrown forcibly upwards into the air. after rising often for great heights they soon fall again on the sides of the mountain. but besides the breaking up of the stopper, the lake in the crater of the volcano is thrown out along with the cinders or ashes, producing very destructive flows of what are called aqueous lava or mud streams. these streams flow down the sides of the mountain, carrying with them immense quantities of both the ashes thrown out during the eruption, or those that have collected around the sides of the crater during previous eruptions. very frequently, these streams of aqueous lava produce greater destruction than the molten lava. if you have ever watched common ants at work clearing out or enlarging their underground homes, in a piece of smooth gravel walk in your garden, you can form some idea why the mountain immediately around a volcanic crater is conical in shape. if the colony of ants happens to be fairly large, you can see an almost unbroken stream of these industrious little animals, each bearing in its mandibles a small grain of sand or gravel brought up from some place below the surface. carrying it a short distance from the opening, it throws it on the ground, rapidly returning for another load. in this way there is heaped up around all sides of the opening a pile of sand or gravel, the outward slopes of which gives the pile a conical form. you have, probably, noticed that the steepness of the slopes depends on the size of the grains; for the larger these grains the sharper or steeper the slopes, the very fine grains producing flat mounds or cones. it is the same with a volcanic cone. the materials that are thrown upwards into the air, falling again on the mountain, collect around the crater on all sides, thus giving it the characteristic cone-like shape of the volcanic mountain. where nothing occurs to disturb the formation of the cone its height above the level of the sea will gradually increase. very frequently, however, during explosive eruptions, a large part of this cone will be blown away by the force of the eruption only to be again built up during some later eruption. indeed, in the case of volcanic islands, the force of a great volcanic eruption is sometimes so great that not only is a large volcanic mountain blown entirely away, but a hole is left, where it had been standing, that extends further downwards below the level of the sea than the top of the mountain extended previously above it. the above are some, but by no means all, the wonders attending volcanic eruptions. we shall refer to others in subsequent chapters in describing particular eruptions. chapter iii the volcanic island of hawaii the volcanic island of hawaii, the largest of the sandwich island chain, is situated in the mid pacific, south of the tropic of cancer. as shown in fig. , this island chain consists of hawaii, maui, molokai, oahu, kauai, nihau, and about eight large islands, together with numerous small islands, extending in a general northwest direction from hawaii to nihau, a distance of about miles. like most volcanic islands they lie in more or less straight lines, probably along fissures, in this case in two nearly parallel lines. the island of nihau, however, is an exception, the direction of the greatest length being almost straight across the two parallel lines. the sandwich islands lie , miles from san francisco in deep water, between , and , fathoms, or between , and , feet in depth. this island chain consists of great volcanic mountains, that had, at one time, fifteen active volcanoes of the first class. these are now all extinct but three, and all of these are on the island of hawaii. in his report to the united states geological survey for - , dutton states that the summit of mt. haleakala on east maui is , feet above the sea level. oahu has peaks on its eastern side , feet high, and peaks on the western side , feet high. the summit of kauai is probably , feet above the sea. [illustration: fig. . the hawaiian islands _from u. s. geological survey_] it can be shown by deep-sea soundings that all these volcanic piles are the summits of a gigantic mountain mass that rises abruptly from the bed of the pacific. there are reasons for believing that this submarine chain continues for many hundreds of miles in the same direction beyond kauai. the extinct volcano, haleakala, on east maui appears to have been in eruption at a much later day than mt. kea, which is also an extinct volcano. but the natives have no traditions of any eruptions. the volcanoes on the other islands have been extinct for a very long time judging from the extent of their erosion. dutton is of the opinion that the western islands of the chain have been extinct for much longer times than the remaining islands. the sandwich islands, also known as the hawaiian islands, are one of the colonial possessions of the united states. the island of hawaii is about , miles from san francisco. honolulu, on the island of oahu, the principal seaport of the chain, has a pleasant climate, and is an important coaling station for warships, commercial vessels, whalers, and trading ships generally. the principal product of the island is sugar cane. the island of hawaii, as shown in map, fig. , consists of five volcanic mountains and some small coral reefs. these mountains are: mt. kea, on the north, , feet in height; mt. haulalai, in the west central part of the island, , feet in height; mt. loa, in the south central part of the island, , feet in height; mt. kilauea, twenty miles east of the crater of loa, , feet high at the volcano house, and , feet on the highest point on the west, and kohala, , feet in height, running through the northwestern part of the island, and the kohala mountains in the northwestern part. [illustration: fig. . hawaii _from dana's manual of geology_] of these mountains, mt. loa and kilauea are the only active volcanoes, and are in frequent eruption. mt. haulalai was in eruption during . mt. kea has not been active during historical times, while mt. kohala has been inactive for so long a time that its slopes are deeply gullied wherever the rivers flow down them. as you can see from the map, hawaii is very large. it has a length of ninety-three miles from north to south, and a breadth of eighty miles from east to west, its area is about , square miles. with the exception of small patches of coral reefs, hawaii is formed entirely of lava, and is the largest pile of lava in the world with the single exception of iceland. where the islands of the hawaiian chain have coral reefs extending off their coasts, excellent harbors are found in the deep waters between the islands and the reefs. hawaii, however, has no extended reefs of this character, and, consequently, no first-class harbors. hilo, on the eastern coast, is the best harbor, and is, therefore, the principal settlement. a very brief examination of the map of hawaii will show you that there are no rivers on the island, except on the sides exposed to the wind, that is, on the northern and northeastern slopes. since the yearly rainfall on hawaii is large, being in the neighborhood of a hundred inches, you will understand that considerable rain water falls on the island. in those parts of the island where it does not run off the surface it must drain downward through the loose piles of broken rocks or cinders. a rainfall of one hundred inches a year means that if all the rain which falls on each square foot of surface was collected in a flat vessel one foot square with vertical sides it would fill the vessel to the depth of one hundred inches, or over eight feet. the drainage of the rainwater downwards through these parts of the island, must, therefore, be large. another curious fact you can notice on the map, is that the lava streams of the past fifty years from mt. loa indicated by heavy dotted lines, in no cases begin at the crater, but start at fairly considerable distances from it. later on in this chapter we shall explain the reason for this curious fact. since practically the whole of hawaii has been formed from the streams of lava that have flowed at one time or another, you can understand how great these flows must have been. but to do this fully you must not only take into consideration the portions of the island that lie above the ocean and reach into the air at its greatest height to , feet above its surface, you must also remember that this mountain rises from a deep ocean, so that if all the water were removed, you would see hawaii towering up above the former level of the sea to the height of about , feet, or higher than mt. everest, the highest point on the earth above the present sea level. this would be, approximately, five and eight-tenths miles. you can understand, therefore, how great the flow of lava must have been. we shall begin the description of hawaii with the active volcano of mt. loa, or, as it is sometimes called in hawaii, "the white mountain." you will remember that the eruption of krakatoa was of the explosive type. practically no melted rock or lava escaped from the crater. indeed, if it had escaped it would not have been seen; for, not only the cone near the crater, but also much of the mountain itself was blown completely out of sight and covered by the waters of the ocean. the eruptions of mt. loa are of an entirely different type. in loa there are no explosions, the eruptions being what are called the non-explosive or quiet volcanic eruption type. it will be necessary to explain some of the peculiarities of this kind of eruptions. there is a great difference in the liquidity or the ease with which different kinds of lava flow. some lava is very thick or viscid, or is sticky like thick molasses or tar, and therefore flows very sluggishly. other lava is thin or mobile, more closely resembling water in the ease with which it flows. now, in the case of a volcanic mountain of fairly considerable height, where the lava possesses marked liquidity, the lava as it rises from great depths in the tube of the volcano seldom flows over the top or rim of the crater. this is not because the force that brings the lava up is unable to carry it a few thousand feet higher, so that it can run over the brim of the crater, but because the walls of the volcanic mountains are unable to stand the great pressure which the mass of liquid lava exerts against their sides. it can be shown that a column of liquid lava feet high, will exert a pressure on the walls of the crater of about pounds to the square inch. therefore, in very high volcanic mountains, long before the lava can reach the edge of the crater and overflow, the pressure becomes so great, that cracks or fissures are made in the sides of the mountain, through which the lava is quietly discharged; when, of course, the level of the lava in the crater falls considerably. in volcanoes of the explosive type, no matter what may be the condition of lava, should a large quantity of water suddenly find an entrance to a large body of molten lava at some distance below the surface, the lava would be suddenly thrown explosively into the air, where being chilled, it would afterwards descend in showers of ashes, cinders, or volcanic dust. in some volcanic mountains such as mt. loa, the crater, instead of being situated at the top of a conical pass of ashes or other material, consists of a pit-like depression, generally occupying a level tract or plain at the top of the mountain. this pit is known as a _caldera_, or _caldron_, or what you might, perhaps, call a huge kettle or boiler. the pit has more or less vertical sides that extend downwards for unknown depths to the place from which the lava comes. the vertical walls of the caldera are not, however, smooth, but exhibit numerous horizontal ledges, that mark places where portions of the floor of the caldera were situated at different times. at the bottom of the large pit or caldera on the summit of mt. loa can be seen the level floor formed of hardened lava. this floor is surrounded by vertical walls on which can be seen the broken edges of the old lake bed. captain dutton, in a paper on hawaiian volcanoes, prepared for the united states geological survey, and published in its fourth annual report for - , thus describes the appearance at the great crater as it was in . "the summit of mauna loa (mt. loa), is a broad and large platform about five miles in length and four miles in width, within which is sunken the great caldera called mokuaweoweo. the distance from the point where we first reach the summit to the brink of the pit is about a mile and a half. the surface of the platform is much more rugged than the slopes just ascended. it is riven with cracks, and small faults,[ ] and piles of shattered rock are seen on every hand. nowhere is there to be seen the semblance of a cinder cone. doubtless many eruptions have broken forth from the various fissures on this summit, but only here and there can insignificant traces of such catastrophes be definitely distinguished. the absence of fragmental ejecta (broken rock that are thrown out) is extraordinary. the shattered blocks, slabs, and spalls (chips) which everywhere cumber the surface appear to have resulted from the spontaneous shivering and shattering of the lava sheets by their own internal tensions as they cooled. fig. , taken from dutton's report, gives the general shape of this great caldera. dutton's description of the same is as follows: "the length of the main caldera is a little less than three miles and its width about a mile and three-quarters. its floor, viewed from above, appears to be composed of a series of flat surfaces occupying two distinct levels, the higher upon the surface of the black ledge, the lower lying within the ledge. upon the western side is a small cinder cone standing close upon the border of the black ledge. it is the only one visible, either within the caldera or upon the surrounding summit. its height is about or feet. it was seen in operation, throwing up steam, clots of lava, and lapilli (some of the larger pieces of fragmentary lava) in the year . the only other diversifications of the floor are many cracks which traverse it, the larger of which are distinctly visible from above. some of them are considerably faulted. there is no difficulty in recognizing the fact that the whole floor has been produced by the sinkage of the lava beds which once continued over the entire extent of the depression, their undersides having been melted off most probably by the fires beneath. the lava beds in the immediate vicinity of the brink upon the summit platform wear the aspect of some antiquity. they have become brown and carious by weathering, and, although no soil is generated, little drifts of gravel are seen here and there mixed with pumice. since the caldera was formed there is no indication that the lavas have anywhere overflowed its rim. and yet it is a very strange fact that within a half mile, and again within a mile to a mile and a half, lavas have been repeatedly erupted within the last forty years from the summit platform, and have outflowed at points situated from to feet above the level of the lava lake within. traces may also be seen, at varying distances back of the rim, of very many eruptions in which the rocks betoken great recency, although no dates can be assigned to their occurrence." [illustration: fig. . panorama of mokuaweoweo _from u. s. geological survey_] [illustration: fig. . view of the crater of kilauea from the volcano house _from u. s. geological survey_] during his visit to this great pit, captain dutton succeeded in climbing down the almost vertical walls on the side of the crater, and, reaching the surface of the hardened lake, walked over it. it must have required no little courage to thus venture on the thin floor of a lake which he knew was filled to great depths with red hot boiling lava, for he was walking over the surface of a slumbering volcano, that might at almost any moment awaken, and opening, swallow him and his companions. through enormous cracks in the floor, he could feel the heat from the molten mass, while, through the same openings came suggestive whiffs of sulphur vapor. during the eruption of this mountain, on january d, , the light from the glowing lava streams was bright enough to read fine print at hilo, a distance of thirty-five miles. during the eruption of , a stream of white-hot lava was thrown up into the air from one of the fissures to a height of from to feet. [illustration: stones and lava thrown upwards--eruption of mokuaweoweo, hawaii, july - , _from a stereograph, copyright, by underwood & underwood_] when an eruption takes place in mt. loa the column of lava slowly rises in the crater, threatening to overflow its lowest edges, but before this can take place the pressure becomes so great that some portion of the mountain below the crater is fractured and the lava quietly escapes. during some conditions of the mountain every fifteen or twenty minutes a column of highly glowing lava is shot upwards like a fountain to a height of feet and over, falling back into the lake in fiery spray. unusual heights of these streams are generally followed by an eruption. these curious jets of molten rock certainly cannot be due to the pressure of higher columns of lava, since the crater itself is near the top of a high plain. they are believed to be due to steam formed by the penetration of the rain water that falls on this part of the mountain. you can now understand why the lava streams escaping from mt. loa as shown on the map, in fig. , do not begin at the level of the crater; for the discharge of the lava does not take place over the rim of the crater, but through the cracks or fissures formed further down the sides of the mountains. it must not be supposed, however, that the fissures are limited to the sides of the mountain where they can be seen. they probably occur in many places below the surface of the water on some part of the bed of the ocean. the crevices that are formed in this manner in the sides of the mountain vary greatly in size, some being so narrow that the lava scarcely flows through them at all but simply fills up the crevice, hardens on cooling, and mends the cracks in the mountains, in the way that a crack is mended in a piece of china by the use of glue or in a wall of masonry by mortar. through the largest crevices or cracks, however, large lava streams may continue to flow often for several weeks, or even longer. sometimes, especially towards the close of the eruptive flow, the lava may escape disruptively, so that small cones are formed along the lines of the fissures. cones of this character are called lateral cones, and in the case of a volcanic island, where the lava flows out below the level of the water, the lateral cones sometimes project above the water and form volcanic islands or dangerous shoals that impede navigation. when the lava pours out of a crevice in the side of the mountain, a river of molten rock rushes down the slopes, at first like a torrent, but on reaching the more nearly level ground, it spreads out in great lava lakes or fields, the surface of which takes on the characteristic black appearance of basalt, a certain kind of glass, for the lavas of mt. loa are generally basaltic. after an eruption the hardened floor of lava in the caldera, being no longer supported by the liquid mass formerly below it, falls in, leaving a large cavity with only the edges of the old floor clinging to the sides of the pit. it will be interesting to give a short account of some of the great lava streams that have been poured out at different times from mt. loa. in the great eruption of august th, , the lava escaped through fissures from two to thirty inches in width. then, flowing in a continuous stream, it did not stop until it was within five miles of hilo. in the eruption of january d, , the lava stream flowed towards the northwest on the east side of haulalai, reaching the sea in eight days. the eruption of march th, , was characterized by severe earthquake shocks, one of which, occurring on the second of april, destroyed many houses and produced huge fissures in the earth. these shocks produced great earthquake waves that reached distant coasts. mt. kilauea, lies at a lower level towards the east. this crater is situated at , feet above the level of the sea, and is nearly , feet below the caldera on the top of mt. loa. fig. , taken from the united states geological survey, fourth annual report, for - , shows a view of kilauea from the volcano house. dutton gives the following description of the appearance of halemaumau, the pit crater or caldera of kilauea. "in front of us and right beneath our feet, over the crest of a nearly vertical wall, more than feet below, is outspread the broad floor of the far-famed kilauea. it is a pit about three and a half miles in length, and two and a half miles in width, nearly elliptical in plan and surrounded with cliffs, for the most part inaccessible to human foot, and varying in altitude from a little more than feet to a little more than feet. the altitude of the point on which we stand is about , feet above the sea.... "the object upon which the attention is instantly fixed is a large chaotic pile of rocks, situated in the centre of the amphitheatre, rising to a height which by an eye estimate appears to be about to feet. from innumerable places in its mass volumes of steam are poured forth and borne away to the leeward by the trade wind. the color of the pile is intensely black.... "around it spreads out the slightly undulated floor of the amphitheatre, as black as midnight. to the left of the steaming pile is an opening in the floor of the crater, within which we behold the ruddy gleams of boiling lava. from numerous points in the surrounding floor clouds of steam issue forth and melt away in the steady flow of the wind. the vapors issue most copiously from an area situated to the right of the central pile, and in the southern portion of the amphitheatre. desolation and horror reign supreme. the engirdling walls everywhere hedge it in. but upon their summits, and upon the receiving platform beyond, are all the wealth and luxuriance of tropical vegetation heightening the contrast of the desolation below...." [illustration: fig. . crater of kilauea _from dana's manual of geology_] fig. represents the pit-like crater of kilauea as it appeared after the eruption of . here, as will be seen, there are several lakes of lava, the largest of which is known as halemaumau. the eruption of , like all the eruptions of kilauea, consisted of the escape of the lava from an opening on the side of the mountain below the crater, and a sinking in of the hardened floor of the crater. the figure also shows the position of the new lake that lies east of halemaumau. the extent and appearance of each of these lakes are constantly changing, both as to height and area. dutton gives the following description of the appearance of the lake of lava, and some curious phenomena that occur on its surface. he is describing the general appearance of the pool of molten lava covered as it is with a hardened black crust: "the surface of the lake is covered over with a black solidified crust showing a rim of fire all around its edge. at numerous points at the edge of the crust jets of fire are seen spouting upwards, throwing up a spray of glowing lava drops, and emitting a dull, simmering sound. the heat for the time being is not intense. now and then a fountain breaks out in the middle of the lake and boils freely for a few minutes. it then becomes quiet, but only to renew the operation at some other point. gradually the spurting and fretting at the edges augment. a belch of lava is thrown up here and there to the height of five or six feet, and falls back upon the crust. presently, near the edge, a cake of the crust cracks off, and one edge of it bending downwards descends beneath the lava, and the whole cake disappears, disclosing a naked surface of liquid fire. again it coats over and turns black. this operation is repeated edgewise at some other part of the lake. suddenly a network of cracks shoots through the entire crust. piece after piece of it turns its edge downwards and sinks with a grand commotion, leaving the whole pool a single expanse of liquid lava. the lake surges feebly for awhile, but soon comes to rest. the heat is now insupportable, and for a time it is necessary to withdraw from the immediate brink." it is very curious to think of cakes of hardened lava floating on the surface of molten lava, but, of course, this is just as natural as cakes of ice floating on the surface of water; for a cake of hardened lava is, as you will understand, only a cake of frozen lava, and, being lighter than the molten lava, must, of course, float on its surface. the disappearance of these cakes of frozen lava and their remelting is still more curious, and can be explained as follows: the frozen or solidified mass of black basalt is a trifle lighter than the lava on which it is floating only while its temperature is high, and therefore expanded by heat. as soon as it cools, its density increases, and when it becomes a little greater than that of the liquid lava, it begins to sink and soon disappears. [illustration: fig. . sections of kilauea at different periods _from dana's manual of geology_] professor dana, who has made a careful study of the phenomena of kilauea, shows in fig. , a cross section of kilauea at different times. before the eruption of , the depth of the crater was from to , feet. at the eruption the bottom to feet, making the depth of kilauea over this deeper central part about , feet. the varying depths at different dates are clearly marked on the drawing. the eruptions of kilauea generally occur as follows: first there is a slow rising of the lava in the crater. this rising continues until the pressure is so great that the mountain is ruptured at some lower place. next a discharge of the lava and a sinking to a level in the conduit that will depend on the position of the crevice. then a gradual falling in of the hardened floor of the lake, a portion of the horizontal walls remaining on the sides of the caldera. the eruption of kilauea, however, has not always been of the quiet type. there was an eruption in the year that would appear to have been of the explosive variety. the following account is given by dana as taken from a history of the sandwich islands by the rev. i. dibble, published in : "the army of keoua, a hawaiian chief, being pursued by kamehamoha, were at the time near kilauea. for two preceding nights there had been eruptions, with ejections of stones and cinders. the army of keoua set out on their way in three different companies. the company in advance had not proceeded far before the ground began to shake and rock beneath their feet, and it became quite impossible to stand. soon a dense cloud of darkness was seen to rise out of the crater, and, almost at the same instant, the thunder began to roar in the heavens and the lightning to flash. it continued to ascend and spread around until the whole region was enveloped, and the light of day was entirely excluded. the darkness was the more terrific, being made visible by an awful glare from streams of red and blue light, variously combined through the action of the fires of the pit and the flashes of lightning above. soon followed an immense volume of sand and cinders, which were thrown to a great height, and came down in a destructive shower for many miles around. a few of the forward company were burned to death by the sand, and all of them experienced a suffocating sensation. the rear company, which was nearest the volcano at the time, suffered little injury, and after the earthquake and shower of sand had passed over, hastened on to greet their comrades ahead on their escape from so imminent a peril. but what was their surprise and consternation to find the centre company a collection of corpses! some were lying down, and others were sitting upright, clasping with dying grasp their wives and children, and joining noses (the mode of expressing affection) as in the act of taking leave. so much like life they looked that at first they supposed them merely at rest, and it was not until they had come up to them and handled them that they could detect their mistake." mr. dibble adds: "a blast of sulphurous gas, a shower of heated embers, or a volume of heated steam would sufficiently account for this sudden death. some of the narrators who saw the corpses, affirm that though in no place deeply burnt, yet they were thoroughly scorched." as you will see in chapter xi, this sudden and awful death due to highly heated air and dust particles, caused even a greater loss of life in the catastrophic eruption of pelée, in martinique on may , . by reason of its situation at a lower level on the slopes of mt. loa, kilauea was at one time thought to be one of the craters lower down on the slopes of loa. this was the opinion of professor dana when he examined the district in . since this time the region has been more carefully studied, and mt. loa and kilauea, are now generally regarded as separate and independent volcanoes, neither of which acts as a safety valve for the other. we shall not attempt in this chapter to say anything concerning the sources or places from where these great supplies of lava have been drawn. this will be left to some subsequent chapter, after we have described still other volcanoes. the outlines of mountains like mt. loa or kilauea differ greatly from mountains like vesuvius; their slopes, like the slopes of all other hawaii volcanoes, have an inclination which does not exceed °. the lava streams, therefore, as they flow down the mountains, move more slowly than they would were the slopes more precipitous, as in mountains like vesuvius. there have been many eruptions of kilauea. that which occurred in the year , was of great magnitude (see map, fig. ), and began in a fissure southwest of the crater. the principal eruption, however, broke out about twelve miles from the sea coast, and about twenty-five miles east of kilauea. here an enormous mass of lava forming a stream nearly three miles wide reached the ocean at nanawale. when an eruption takes place on mt. loa through a fissure at the height of , to , feet the length of the lava streams is frequently as great as twenty-five to thirty miles. often the lava though hardening at the surface will continue to flow underneath through huge tunnels, of which the top and sides are composed of solidified parts of the same lava stream. after the flow has ceased long hollow tunnels often remain. if the lower end of such a tunnel containing molten lava is momentarily closed, the pressure of the lava above may not only burst through the obstruction, but may even throw the lava upwards in jets to feet high. probably most of you have seen illumined fountains where jets of water are beautifully lighted up by different colored electric lights placed below them. such fountains, however, can but poorly compare either in beauty or grandeur with these wonderful lava fountains, common on the slopes of mt. loa during an eruption. chapter iv the volcanic island of iceland the island of iceland consists of a number of volcanic mountains some of which are still active. as can be seen from the map, shown in fig. , iceland lies in the north atlantic ocean, immediately below the arctic circle, about miles east of greenland, and miles west of norway. its length from east to west is about miles, and its breadth about miles, its total area, including the adjacent islands, being more than , square miles. were all the water removed from the north atlantic ocean, it would be seen that iceland rests on the bed of the atlantic, on a submarine plateau or highland; for, in this part of the ocean the water is only from , to , feet deep. this submarine plateau extends as far as norway on the east, greenland on the north, and the island of jan mayen on the northeast. immediately north of the plateau the ocean suddenly drops to a depth of , to , feet. [illustration: fig. . iceland] toward the south the plateau extends with but few interruptions through the middle of the ocean to a shoal known as the _dolphin shoal_, as far as lat. ° n. this part of the ocean, which can only relatively be called a shoal, is not generally deeper than , feet, although in some places the water is more than , feet deep. on each side of the dolphin shoal the water is much deeper, being in places , feet on the east, while on the west there are depths as great as from , to , feet. this sunken plateau, possibly including the shallower plateau on the north, is believed by some to be the remains of the fabled continent of _atlantis_, to which we shall refer in another part of this book. the coast line of iceland is unbroken on the southeast, but the remainder of the coast is deeply indented with bays or fiords in which are many excellent harbors. iceland is liable to frequent earthquake shocks and volcanic eruptions. from careful records that have been preserved in the history of the island, we learn that since the beginning of the twelfth century there have practically never been intervals longer than forty years, and more generally not longer than twenty years, in which there has not been a great earthquake or a great volcanic eruption. these volcanic eruptions are often very protracted. for example, one eruption of the volcano hecla continued for six years without ceasing. sir charles lyell, the great english geologist, writes as follows about iceland: "earthquakes have often shaken the whole island at once, causing great changes in the interior, such as the sinking down of hills, the rending of mountains, the desertion of rivers by their channels, and the appearance of new lakes. new islands have often been thrown up near the coast, some of which still exist, while others have disappeared, either by subsidences or the action of the waves. "in the interval between eruptions innumerable hot springs afford vent to the subterranean heat, and solfataras discharge copious streams of inflammable matter. the volcanoes in different parts of the island are observed, like those of the phlegræan fields, italy, to be in activity by turns, one vent often serving for a time as a safety valve for the rest. many cones are often thrown up in one eruption and in this case they take a linear direction, running generally from southeast to northwest." the volcanic eruptions of iceland belong for the greater part to the fissure type. during a volcanic eruption in iceland the ground is split in fissures or cracks, generally parallel to each other, and varying in width from a few inches to several yards. these fissures extend for great distances across the country. the lava quietly wells out along the fissures not unlike the way quiet spring waters flow from their reservoirs. according to dr. th. thoroddsen, the icelandic geologist, there are two systems of fissures extending through iceland, from southwest to northeast in the southern part of the island, and from north to south in the northern part. where two lines of fissures cross each other the points of intersection may be especially active. dr. th. thoroddsen arranges the volcanoes of iceland under three heads, i. e., _cone-shaped volcanoes_; _lava cones_; and _chains of craters_, the last being the commonest. out of volcanoes examined by him in iceland, eight were of the vesuvian type, or were built up of layers of lava and volcanic ashes; sixteen were of the lava-cone type, similar to mt. loa, of the hawaiian islands, and the remaining eighty-three were of the type of crater chains. the volcano of snaefell jökul, , feet above the level of the ocean, is built up of alternate layers of lava and hardened volcanic mud. it is not, however, a true cone-shaped mountain. the largest volcano in iceland, the dyngjufköll, with its immense crater of askja, has an area of some twenty-five square miles. in its form it resembles snaefell. volcanoes of the lava-cone type have been built up entirely of lava and have a slight angle of inclination. these volcanoes range in size from small hillocks to the largest mountains on the island. their cones generally stand on a base of wide circumference and frequently rise to great heights, the top being occupied by a caldera, or pit crater like that on mt. loa or kilauea. volcanoes of the type of chain-craters follow the natural fissures in the crust. these craters are generally low, seldom being more than feet high. there are also seen in iceland caldron-shaped depressions that have been formed by explosive eruptions. one of the best instances of such craters is viti, on the side of mt. krafla. this crater was formed by the sudden eruption of may th, . the lava sometimes quietly runs out of the entire length of the fissure without forming any cone. this was the case of a great fissure known as the eldgja chasm. here three lava streams covered an area of square miles. as the lava comes out of the fissures, it generally produces long ramparts of slags, and blocks of lava that are piled up on either side of the fissure. sometimes a line of low cones is built up. these cones consist of heaps of slag, cinders, and blocks of lava. their craters are not rounded as in the case of volcanoes of the vesuvian type, but are oblong, or have their greatest diameter extending in a direction of the fissure. icelandic lava as it escapes from the fissures is peculiar in that it is very viscid or plastic and can be readily drawn out into long threads that can be spun into ropes. when such lava runs down the sides of a steep slope, it often splits on cooling into separate blocks. where it runs over flat, level ground, however, it spreads uniformly on all sides, producing vast level lava deserts that are as flat as the surface of a well built floor. there are many rivers in the north and the west of iceland. now, as the lava streams flow out of the fissures they enter the channels of the rivers so that the streams of water must find new paths to the sea, and this operation may be repeated again and again. often the time between eruptions is long enough to give the rivers opportunity to cut deep channels or gorges in their new channels; but on the next escape of the lava these gorges and valleys are again filled with the molten rock, and the rivers must begin their channel cutting all over. you will note the frequent use of the word jökul, as snaefell jökul, skaptar jökul, orefa jökul, etc. the name jökul means a large mass of ice, or a mountain that is continually covered with snow, for example, snaefell jökul, is a beautifully shaped, snow-covered mountain situated on a point of land on the western coast of the island, extending out nearly fifty miles into the sea, between the faxa fiord and the briela fiord. it is a very conspicuous object, being visible to passing ships at considerable distances from the island. orefa jökul is the highest mountain in iceland. skaptar jökul is one of the active volcanoes of iceland. there can be no doubt that iceland has been formed entirely by lava thrown up from the bottom of a submarine plateau, until it extended above the surface of the waters. to make an island entirely of lava with an area of , square miles, must, of course, have required many cones or craters that continued to pour forth lava for periods of time much longer than those during which man has lived on the earth. the surface of iceland is far from attractive. the interior is practically a vast lava desert, covered with snow-clad mountains or jökuls. there is no plant life except in marshy lands near the coasts, and even here scarcely enough grass is raised to feed the few cattle and horses owned by the inhabitants. there is no agriculture, owing to the very short summers, so that all grain is brought from europe. every now and then the grass crop is destroyed by accumulation of polar ice on the northern and western coasts. such failures are always attended by great famines, when many of the people die. should you ever visit iceland you would probably be surprised to hear the people speaking about their forests. you might go over all the coasts of the island without seeing anything larger than a birch bush, not much higher than six feet. these are what the icelanders like to speak of as their forest trees, and i suppose there is no harm done, if one only understands just what they mean by "trees." while, however, iceland has practically no trees, yet it has no difficulty in obtaining a plentiful supply of timber, since in the deep fiords or bays on the western and southern coasts there can always be found much drift timber brought there by the ocean currents from the forests of america. the principal town or settlement in iceland is reykjavik, the capital of the island, on the southwestern coast; this is the chief trading place on the island. thingvalla is also an important town. the lavas that form the entire mass of iceland were thrown out both before and since the glacial age. it is the opinion of geikie that these outflows have continued uninterruptedly since that age to the present time. it is known that the lavas of iceland were thrown out both before and after the glacial age, because during the glacial age, deep cuttings or groovings were made on the surface of the earth by the glaciers as they slowly moved over it. now lava beds containing the glacial scratches have been found and resting on them are other lava streams. the scratched lavas must, therefore, have been thrown out before the glacial age, and the second lavas after that age. let us now examine some of the more active volcanoes of iceland and their eruptions. we will begin with the well-known volcano of skaptar jökul. the following description of this volcano has been taken from a book on iceland by e. henderson, published in boston, . skaptar jökul lies in the south central part of iceland about forty odd miles from the coast. it takes its name from the skaptar river, down whose channel the lava flowed its entire distance of forty miles from the ocean. skaptar jökul consists of about twenty conical hills lying along one of the fissures that extends from northeast to southwest. it appears from henderson's account that people living in the neighborhood of skaptar jökul were greatly alarmed by repeated earthquakes that were felt at different times from the first to the eighth of june, . these earthquake shocks increased in number and violence, so that the people left their homes and awaited in terror the coming catastrophe. on the morning of the eighth a prodigious cloud of dense smoke darkened the air, and the surrounding land soon became covered with ashes, pumice, and brimstone. as is common with eruptions in iceland, that have been preceded by long periods of rest, the heat produced by the escaping lava and the sulphurous gases, melted such quantities of ice that great floods were produced in the rivers. on the th of june vast torrents of lava that had been escaping from the craters entered the valley of the skaptar river, and commenced flowing through its channel. immense quantities of steam were produced, and, in less than twenty-four hours, the river was completely dried up, for the lava had collected in the channel, which in many places flows between high rocks from to feet in height and nearly feet in breadth, and had not only filled the river to its brink, but had overflowed the adjacent fields to a considerable extent, and flowing along the cultivated banks of the river destroyed all the farms in its path. on gaining the outlet, where the channel of the skaptar emerged into the plain, it might have been supposed that the burning flood would have at once spread over the low fields, which lay immediately before it, but, contrary to all expectations, this flow was for a time stopped by an immense unfathomed abyss in the river's bed, into which it emptied itself with great noise. when this chasm was at last filled, the lava increased by fresh flows, rose to a prodigious height, and breaking over the cooled mass, proceeded south towards the plain. in the meantime the thunder and lightning, together with subterranean roars, continued with little or no intermission. on the th of june, , another dreadful eruption of red hot lava came from the volcano. this flowed with great velocity and force over the surface of the cooling stream that had been thrown out principally on the tenth of the month. floating islands consisting of masses of flaming rock were seen on the surface of the lava stream, and the water that had been banked up on both sides of the stream was thrown into violent boiling. in the meantime people living along the hverfisfloit, the next largest river to the east of the skaptar, had not yet been visited by the lava streams. it is true that their vegetation had been destroyed by showers of red hot stone and ashes, and that both atmosphere and water were filled with poisonous substances. the land had also been plunged in utter darkness, so that it was scarcely possible at noonday to distinguish a sheet of white paper held up at the window from the blackness of the wall on either side. but the molten lava streams had not yet reached the people of this valley and they hoped that the eruption would soon be over, and that the lava flow would continue to follow the skaptar. on the d of august, however, they were alarmed by seeing steam escaping from the river hverfisfloit, and soon all its water was dried up, and a fresh lava flow poured down upon them. as in the case of the skaptar, the melted rock completely filled the empty channel to the brink, and then overflowing, covered the low grounds on both sides, so that by the ninth of august it had reached the open and level country near its mouth and in the course of a few hours spread itself for a distance of nearly six miles across the plain. this flow continued after the end of august, and, indeed, even as late as the month of february, , when a new eruption took place in this part of the country. hecla, another well-known volcano in iceland, situated about thirty miles from the southern coast, consists of three peaks, the central of which is the highest. its craters form vast hollows on the sides of these peaks, and at the time of the eruption in were covered with snow. hecla is believed to have been an active volcano long before iceland was inhabited. no less than twenty-three eruptions have been recorded between a. d. and the great eruption of - . volcanic history frequently repeats itself. there had been no great eruption of hecla for a period of about twelve years, and the people living in the neighborhood were congratulating themselves on the belief that the mountain was becoming actually extinct, and that therefore they need not trouble themselves about eruptions. others, however, more farseeing, pointed out the fact that the lakes and rivers in the vicinity did not freeze, and that the amount of water they contained was greatly decreased. the following description of the great eruption of hecla that was remarkable both for its violence, as well as for the time during which it continued, is taken from symington's "sketches of faroe islands and iceland": "on the th of april, , there were some slight shocks of an earthquake, and early next morning a pillar of sand, mingled with fire and red hot stones, burst with a loud thundering noise from its summit. masses of pumice, six feet in circumference, were thrown to the distance of ten or fifteen miles, together with heavy magnetic stones, one of which, eight pounds weight, fell fourteen miles off, and sank into ground still hardened by the frost. the sand was carried towards the northwest, covering the land, miles round, four inches deep, impeding the fishing boats along the coast, and darkening the air, so that at thingore, miles distant, it was impossible to know whether a sheet of paper was white or black. at holum, miles to the north, some persons thought they saw the stars shining through the sand-cloud. about mid-day, the wind veering round to the southeast, conveyed the dust into the central desert, and prevented it from totally destroying the pastures. on the th of april, the lava first appeared, spreading about five miles towards the southwest, and on the d of may, a column of water was seen shooting up in the midst of the sand. the last violent eruption was on the th of july, the mountains, in the interval, often ceasing to eject any matter; and the large stones thrown into the air were compared to a swarm of bees clustering around the mountain-top; the noise was heard like loud thunder forty miles distant, and the accompanying earthquakes were more severe at krisuvik, eighty miles westward, than at half the distance on the opposite side. the eruptions are said to be in general more violent during a north or west wind than when it blows from the south or east, and on this occasion more matter was thrown out in mild than in stormy weather. where the ashes were not too thick, it was observed that they increased the fertility of the grass fields, and some of them were carried even to the orkney islands, the inhabitants of which were at first terrified by what they considered showers of black snow." the largest volcano in iceland is dyngjufjoll. this has on its summit the gigantic crater of askja, some twenty-five square miles in area. this crater is of the intermediate form; the most general form of volcanoes on the island consisting of a number of craters that closely follow fissures. professor johnstrup, in a report to the danish government, on this volcano, states that the valley of askja has been gradually filled by repeated flows of lava from enormous craters on the edge of the mountain. in many places the surface of the earth is covered with bright red pumice stone that was thrown out during an eruption march th, . some of these craters are filled with steam that escapes with an almost deafening roar. the surprising feature of this eruption was the immense quantity of pumice stone that escaped. the volcanoes in the nyvatus oraefi are entirely different. this barren plain is thirty-five miles in length and thirteen miles in breadth. suddenly on the th of february, , a volcano appeared in the centre, and four other craters were formed at subsequent dates. the mass of lava that was thrown out of these openings has been estimated at , , , , cubic feet, or eighteen times the estimated mass of lava that has been emitted from vesuvius between and . this lava is basalt. chapter v vesuvius the old greeks and romans had but little knowledge of volcanoes. they only knew the volcanic mountains in the mediterranean sea. here there are three volcanic regions:--one in the neighborhood of naples; one including sicily and the neighboring islands, and the other that of the grecian archipelago. some idea can be had of these three regions from a map of the mediterranean shown in fig. . the principal volcanoes are vesuvius, etna, stromboli, and vulcano, a mountain, by the way, that gave its name to all volcanic mountains. in this chapter we will describe the volcano of vesuvius, the most active, though by no means the largest of the volcanoes of the mediterranean. but, before doing this, it will be well first to describe briefly the volcanic districts surrounding vesuvius. as shown in fig. , this district includes vesuvius, procida, and ischia. [illustration: fig. . the mediterranean] ischia is a small island measuring about five miles from east to west, and three miles from north to south. there were such terrific volcanic eruptions on this island long before the christian era, that several greek colonies were forced to abandon it. a colony established long afterwards, about b. c., by the king of syracuse also had to depart. strabo, the grecian geographer (born about b. c.), states that, according to tradition, terrific earthquakes occurred on the island a little before his time, and its principal mountain threw out large quantities of molten rock, which flowed into the sea. at the time of this eruption there were earthquake waves in the sea, the waters of which slowly receded, leaving large portions of the bottom uncovered, and rushing, afterwards, violently over the land, caused great destruction. it was during this disturbance, so strabo asserts, that the island of procida was formed by being violently torn from ischia. [illustration: fig. . the volcanic district around vesuvius] the phlegræan fields was a name given by the ancients to some of the lowlands in the neighborhood of naples; they were believed to be under the special protection of the roman gods. when the frequent earthquake shocks shook these fields, the roman people believed that conflicts were taking place between their gods and slumbering giants confined in the regions below the surface. it is more than probable that mt. vesuvius has always been the centre of these volcanic disturbances. long before the christian era, however, vesuvius, or somma, the name given to the old crater that then occupied the summit of the mountain, had been an extinct crater. indeed, it had been so quiet that the people who lived on its slopes did not appear to know they were living on the slopes of a slumbering volcano. their knowledge of volcanic mountains must have been very limited, for this mountain with the huge pit at its summit had all the appearance of a volcanic crater. when they climbed to the top of the mountain, which, of course, they frequently did to look after the vineyards they were cultivating on the slopes, and looked down into the deep pit from the rocks on its edge, they could see at the bottom of a great central pit three miles in diameter, a lake, with room here and there to enable one to walk along its borders. the walls of the precipice were covered with luxuriant vines. when we say that none of the people even suspected that vesuvius had ever been in a state of eruption, we must except some of their learned men. for both diodorus siculus, a native of sicily, who lived about b. c., and wrote an universal history, containing some forty volumes, of which only about one-third remain, and strabo, the geographer, pointed out in a general manner, that vesuvius, and much of the surrounding country, looked as if it had been eaten by fire. then, too, a roman philosopher who lived between a. d. and a. d. , spoke of vesuvius being "a channel for the eternal fire!" let us now endeavor to obtain some idea of the appearance of this region a short time before a. d. , when vesuvius burst forth in a terrific eruption. the slopes of the mountain were covered with the rich vegetation that characterizes this part of italy. when most volcanic ashes and lava have been exposed for some time to the atmosphere they make a very fertile soil. now, this soil on the slopes of vesuvius made the vineyards that covered the mountain slopes and the fields for miles around its base, bear very plentifully, so that the people lived very comfortably. here and there on the slopes of the mountain large towns like herculaneum and pompeii had long been established, while, in the distance, was the large city of naples. besides these there were numerous populous towns and villages scattered here and there over the plain or on the lower mountain slope. you have all probably read of the roman gladiator, spartacus. spartacus was a thracian by birth, and while a shepherd had been taken prisoner by the romans and sold to a trainer of gladiators at capua. chaffing under the tyranny of the romans, who forced him to fight in the arena with men and beasts, he revolted against his masters, and with a band of some seventy followers, fled to a mountain fastness in the crater of vesuvius. proud rome sent a few men to recapture him, with scourges for his punishment, but they were beaten by spartacus. every day dissatisfied men like himself escaped from the romans and joined his ranks. rome sent a larger body of men against spartacus, but they also were beaten. at last, recognizing the gravity of the position, the roman prætor, clodius, was sent against spartacus with an army of some three thousand men. clodius caught spartacus in the crater and guarded the only space by which it seemed possible for spartacus to escape. using the vines that covered the precipitous walls of the crater, spartacus did escape, and falling unexpectedly on the armies of clodius, routed them. after this victory, spartacus with an army of over , men overran southern italy, and sacked many of the cities of the roman campania. during this time spartacus defeated one roman army after another, until finally, in the year b. c., crassus was sent against him and vainly endeavored to conquer him. being unsuccessful, crassus urged the roman senate to recall lucullis from asia and pompey from spain, and finally poor spartacus was cut down in a fight he made against crassus and lucullis. but let us come to the great eruption of vesuvius in a. d. . the people living on the slopes of vesuvius were not without plenty of warnings of the dreadful catastrophe that was coming. as early as a. d. there was a great earthquake that shook the country far beyond naples. in pompeii, then a flourishing city, the temple of isis was so much damaged that it had to be rebuilt. even if the earthquake shocks had not foretold the coming eruption, there were other signs. the height of water in the wells decreased. springs that had never before been known to fail, dried up completely. these changes, as we well know, were due to the red hot lava being slowly forced up from great depths into the tube connected with the crater. the earthquake shocks continued at irregular intervals for sixteen years, until, on the th of august, a. d. , about one o'clock in the afternoon, vesuvius burst forth in the terrible eruption that destroyed the towns of pompeii and herculaneum. pompeii was a seaport town situated near the mouth of the river sarno, about fifteen miles southeast of naples. it was a beautiful place, containing many splendid temples. its people for the greater part lived luxuriously, for pompeii was the summer resort of the richer people of naples, some of whom lived there during the hottest months of the year. herculaneum, the other town, was nearer naples, only five miles from the city. it was also, like pompeii, a beautiful town, and contained many splendid buildings. in each town there were magnificent baths and a large theatre. the inhabitants spent so much of their time in the open air, or in the baths, that it was not necessary for them to build very large houses. the houses, however, were well built, and though generally consisting of practically a single story, were provided with all the luxuries that great wealth could command. on august th, a. d. , severe earthquake shocks again visited this part of the world and vesuvius suddenly threw up from its crater an immense column of black smoke, which, rising high in the air, spread out in the form of a huge mushroom, or, perhaps, more like the umbrella pine tree of the neighborhood. rapidly spreading on all sides, the smoke soon completely shut out the light of the sun, and wrapped the earth in an inky darkness, except for a red glare from columns of molten rock that rushed out of the crater. from the dark cloud immense quantities of red hot stones, pumice, and volcanic ashes descended on the earth. at the same time there fell a deluge of rain, caused by the sudden condensation of the enormous amount of water vapor that was thrown out from the crater during the eruption. fortunately, very few of the people were killed in either of the cities of pompeii and herculaneum, although some bodies were found in the ruins. most of the people escaped through the darkness and gloom, continuing to flee from the city for at least three days. both cities were covered so deep with ashes or mud that the tops of the tallest buildings were no longer visible. pompeii was buried by showers of ashes or volcanic cinders, and herculaneum mainly by vast floods of aqueous lava. so completely were these cities covered that their very existence was at last forgotten. it is true that titus, who was then emperor of rome, endeavored to clear away the ashes and rebuild pompeii, but the task was so great that he finally abandoned it. during the year , the architect fontana, while superintending the building of an aqueduct, came across some ancient buildings. at a much later date, in , some workmen, while digging a well in the village of portici, uncovered three marvellously beautiful marble statues. in the year , the same well was dug deeper, when traces of the old theatre of herculaneum were discovered. some effort was then made to excavate the city and many of the public buildings and private houses were uncovered, and statues, mosaics, wall paintings, and charred manuscripts of papyrus were found. a few of these have been unrolled and deciphered, but owing to the difficulty of doing this, without destroying them, the greatest number still remain unread. in , the italian government began a systematic excavation of the buried cities, and now both pompeii and herculaneum are thrown open to the sunlight so that one can walk through the old streets, and look into the houses, in which, before a. d. , the people lived so happily. many interesting stories are told about the discoveries that were made during the government excavations. the skeleton of one of the inhabitants was found grasping a money bag. he might have escaped, but had gone back to get his money. he got it, but remained with it. in another place, the skeletons of a number of people were found in an underground room or cellar of a house, where were also found some mouldy bread and empty water flasks. instead of leaving the city, which they might have done, they had retreated to the underground room for safety, but the fine volcanic dust drifted in and suffocated them. the younger pliny, the historian, has given an excellent account of some features of this great eruption. it appears that his uncle was stationed with the roman fleet, in the bay of naples, at the time of the eruption. he describes the dark cloud of ashes that was formed over vesuvius. he refers to the rapidity with which it spread, and to the showers of ashes, cinders, and stones that it rained down on the earth. his uncle, the elder pliny, landed on the coast, and was afterwards killed by a cloud of sulphurous vapor that swept down the side of the mountain. the following letter from the younger pliny, describing his flight with his mother from misenum, is quoted from dana's "characteristics of volcanoes." "it was now seven o'clock [on the morning of august th], but the light was still faint and doubtful. the surrounding buildings had been badly shaken, and although we were in an open spot [a little yard between his uncle's house and the sea], the space was so small that the danger of a catastrophe from falling walls was great and certain. not till then did we make up our minds to go from the town.... when we were free from the buildings we stopped. there we saw many wonders and endured many terrors. the vehicles we had ordered to be brought out kept running backward and forward, though on level ground; and even when blocked with stones they would not keep still. besides this, we saw the sea sucked down and, as it were, driven back by the earthquake. there can be no doubt that the shore had advanced on the sea, and many marine animals were left high and dry. on the other side was a dark and dreadful cloud, which was broken by zigzag and rapidly vibrating flashes of fire, and yawning showed long shapes of flame. these were like lightning, only of greater extent.... "pretty soon the cloud began to descend over the earth and cover the sea. it enfolded capreæ and hid also the promontory of misenum." ... the flight was continued. "ashes now fell, yet still in small amount. i looked back. a thick mist was close at our heels, which followed us, spreading out over the country, like an inundation." ... turning from the roar in order to avoid the fleeing, terror-stricken throng, they rested. "hardly had we sat down when night was over us--not such a night as when there is no moon and clouds cover the sky, but such darkness as one finds in close-shut rooms. one heard the screams of women, the fretting cries of babes, and shouts of men.... "little by little it grew light again. we did not think it the light of day, but a proof that the fire was coming nearer. it was indeed fire, but it stopped afar off; and then there was darkness again, and again a rain of ashes, abundant and heavy, and again we rose and shook them off, else we had been covered and even crushed by the weight.... at last the murky vapor rolled away, in disappearing smoke or fog. soon the real daylight appeared; the sun shone out, of a lurid hue, to be sure, as in an eclipse. the whole world which met our frightened eyes was transformed. it was covered with ashes white as snow." young pliny and his mother returned to misenum, and survived the perils to which they were exposed. it was during this eruption that a large part of the old crater was blown off the mountain by the tremendous force at work. there have been many eruptions of vesuvius since the great eruption of a. d. . one of these occurred during the reign of severus, a. d. . it was during this eruption that an additional part of the old crater of somma was blown away. another great eruption occurred a. d. . then great quantities of volcanic dust were thrown up into the air, and falling, covered practically all parts of europe, producing darkening of the sun and great fear as far as the city of constantinople. but what was perhaps a still greater eruption occurred during december of . this eruption spread great quantities of ashes over the country for hundreds of miles around, and great streams of mud rushed down the slopes of the mountain. buccini gives the following account of this eruption: "the crater was five miles in circumference, and about , paces deep. its sides were covered with brushwood, and at the bottom there was a plain on which cattle grazed. in the woody parts wild boars frequently harbored. in one part of the plain, covered with ashes, were three small pools, one filled with hot but bitter water; another with water saltier than the sea, and a third with water that was hot but tasteless. but at length these forests and grassy plains were consumed, being suddenly blown into the air and their ashes scattered to the winds. in december, , seven streams of lava poured at once from the crater and overflowed several villages, on its flanks, and at the foot of the mountain. reisna, partly built over the ancient city of herculaneum, was consumed by the fiery torrent. great floods of mud were as destructive as lava. this is no unusual occurrence during these catastrophes for such is the violence of the rains produced by the evolution of aqueous vapors that torrents of water descend the cone and become charged with impalpable volcanic dust, and rolling among ashes, acquire sufficient consistency to deserve the ordinary appellation of aqueous lava." of course, you will understand that we have given only a few of the most notable of the eruptions of mt. vesuvius. since the yea a. d. there have been no less than fifty-six recorded eruptions, that of the year being especially violent. omitting these eruptions we at last come to the great recent eruption of . fortunately, the eruption of , as well as still more recent eruptions that have occurred, have been more accurately described than have most volcanic eruptions, for the italian government, recognizing the value to the natives of italy of a knowledge of what was going on at the crater of vesuvius, has maintained for the past thirty years an observatory on the western part of the mountain. this observatory has been placed in charge of prof. luigi palmieri, a well-known student of volcanoes and earthquakes. at this place records are kept of the behavior of the volcano, of all earthquake disturbances, as well as other phenomena. at the same time, by the use of photography, excellent pictures have been obtained showing the appearance of the sky during an eruption. vesuvius had been in a quiet state from november, , to the year , when small quantities of lava flowed continuously for several months. again, early in , other quiet eruptions of lava continued for weeks at a time. finally, on april th, of that year, a violent explosive eruption occurred. the following account has been taken from palmieri's report, entitled, "the eruption of vesuvius in ." on april d the recording earthquake instruments, the seismographs, were greatly affected. on the evening of the th lava streams flowed down the cone in various directions. these streams were continued on the th and the th, so that on the night of the th the observatory lay between two streams of molten lava that threw out so much heat that the glass windows in the observatory were cracked, and a scorching smell was quite perceptible in the rooms. the cone of the mountain was deeply fissured, lava escaping freely from all the fissures, so that the molten rock appeared to ooze from over its entire surface, or as palmieri expressed it, "vesuvius sweated fire." this great cracking or fissuring of the cone was accompanied by the opening of two large craters at the summit, that discharged, with a great noise, immense clouds of steam, dust, lapilli, and volcanic bombs. these latter are very curious and consist of masses of soft lava that are thrown high into the air by the outrushing columns of steam. being rotated or spun, as they rise in the air, they assume a spherical shape. some of these volcanic bombs were thrown to a height estimated by palmieri to have been nearly , feet above the top of the mountain. when the height of a projectile is known, the velocity with which it left the opening from which it was projected or thrown can be estimated, so that the volcanic bombs must have left the crater at a velocity of about feet per second. on the th, in the evening, the lava streams ceased flowing, but the dust and lapilli continued to fall during the th and the th. on the th the detonations decreased and by the st of may the eruption was entirely over. palmieri calculated that the quantity of molten rock thrown out during this eruption was sufficient to cover an area of about . square miles to an average depth of about thirteen feet. as we can see from the above descriptions, the volcanic activity of vesuvius is characterized by long periods of rest followed by periods of activity. the periods of rest are measured by years, and often by centuries; the periods of activity by days or hours. but vesuvius was not to have a long period of rest after its eruption of . on the contrary, shortly after the great disaster of martinique in , it again became active, and on the th of april, , began throwing large blocks of lava out of its central cone, and on the next day began to throw out large streams of lava, which, on april th, destroyed a village in the neighborhood. at the same time rumbling sounds were heard, and violent earthquake shocks shattered the windows of the houses. professor matteucci, the present director of the vesuvius observatory, made the following report on april the th. "the eruption of vesuvius has assumed extraordinary proportions. yesterday and last night the activity of the crater was terrific, and is increasing. the neighborhood of the observatory is completely covered with lava. incandescent rocks are being thrown up by the thousands, to a height of , feet or even , feet, and falling back form a large cone. another stream of lava has appeared.... the noise of the explosion and of the rocks striking together is deafening. the ground is shaken by strong and continuous seismic movements, and the seismic instruments [instruments employed to record the time, direction, and intensity of earthquake movements] threaten to break. it will probably be necessary to abandon the observatory, which is very much exposed to the shocks. the telegraph is interrupted, and it is believed the funicular railroad has been destroyed." on april th matteucci made the following report: "the explosive activity of vesuvius, which was so great yesterday, and was accompanied by very powerful electric discharges, diminished yesterday afternoon. during the night the expulsion of rocks ceased, but the emission of sand increased, completely enveloping me and forming a red mass from six to ten centimeters deep, which carried desolation into these elevated regions. masses of sand gliding along the earth, created complete darkness until seven o'clock. several blocks of stone broke windows in the observatory. last night the earthquake shocks were stronger and more frequent than yesterday, and displaced the seismic apparatus. yesterday afternoon and this morning, torrents of sand fell." on april th matteucci sent the following report: "last night was calm, except for a few explosions of considerable force from time to time. at four o'clock this morning the explosions became more violent. the seismic instruments recorded strong disturbances." the eruption of vesuvius of was especially noted for the great quantities of sand and ashes thrown out of the crater. the amount of sand that fell on the roof of the market house at monti olivetto was so great that the roof fell in. in this eruption there were some six lava streams that poured down the mountain. the most formidable of these was that which descended towards torre annunziata. here it stopped just short of the wall of the cemetery outside of the town. during this eruption of vesuvius, as in previous eruptions, clouds of volcanic dust collected in the air, shutting off the light of the sun. naples was in a state of semi-darkness. the roofs of the houses were covered to a depth of several inches with an exceedingly fine reddish dust. in some places this dust had drifted into heaps fully a yard in depth. chapter vi other volcanoes of the mediterranean the relative positions of the other volcanic mountains of the mediterranean sea; i. e., etna, stromboli, and the volcanoes of the santorin group of the grecian archipelago, are shown in the map, fig. . we will begin with the volcanic mountain of etna, under which, according to mythology, the angry gods had buried the rebellious typhoon. etna is situated on the island of sicily, immediately southwest of italy. it is a much larger mountain than vesuvius, rising, as it does, from a circular base about eighty-seven miles around, to a height of , feet above the level of the mediterranean. it forms a conspicuous object when seen either from the mediterranean, or from distant parts of italy. the height of etna is so great that its slopes can be divided into three distinct climatic zones or belts. the lowest of these lies between the sea and a height of , feet. in this zone the mountain slopes are covered with cultivated fields, olive groves, orchards, and vineyards. the middle zone lies between , feet and , feet. this zone is covered with forests of chestnuts, oaks, beeches, and cork trees. the third and highest zone includes the rest of the mountain, and may be called the desert zone, since it is a sterile region, covered with huge blocks of lava and scoriæ, and terminating, in the higher portions, in a snow-covered plain, from which the central cone rises. etna is continually sending up columns of steam and sulphur vapor. every now and then it starts in eruption, throwing out large quantities of lava either from the crater on its summit, or from some of the smaller cones or craters that occupy portions of its slopes. on account, probably, of its height the eruptions are most frequently on the sides. etna affords a magnificent example of a huge volcanic pile of the vesuvian type, which has been slowly built up by the gradual accumulation of materials that have escaped from its craters. one of the most interesting features of the higher regions of etna is an immense chasm rent in a side of the cone near the summit, and known as the val del bove. this chasm forms a vast amphitheater. the great force that removed such an immense mass of matter from the cone could not have been the eroding power of water, since the materials of the cone are too porous to permit streams of any size to rush down the slopes. the force is most probably to be found in some explosive eruption of the mountain, when a portion of the crater was suddenly blown off, just as was done in vesuvius when a large part of the old crater of somma was blown away. what is especially interesting about the val del bove is the opportunity it affords for studying the interior structure of the mountain, for it practically enables one to enter to almost the heart of this great volcano. the val del bove has the shape of a great pit five miles in diameter. it has almost vertical walls, the height of which varies with their position. those which reach highest up the mountain vary from , to , feet in height. like vesuvius, etna has been split or fissured into great crevices that have been filled with lava during the many eruptions of its central crater. on hardening, these lava streams form what are known as dikes. as the sides of the mountain are worn away by erosion, the dikes, being harder than the rest of the cone, project from its sides like huge walls. an excellent opportunity for seeing them is afforded in the walls of the val del bove. sir charles lyell, the english geologist, who has carefully studied mt. etna, asserts that this mountain began to be formed during a geological period known as the tertiary age, through a crater that opened on the floor of the mediterranean sea. the material thus thrown out, collected around the crater and produced a mountainous pile that gradually emerged above the level of the sea, and on fresh materials continuing to be thrown out, at length reached its present height. it would appear that at some former time in its history, there were two vents near the top of the mountain, the second crater being formed immediately under the val del bove. soon, however, the second and lower crater was closed, the upper one alone remaining active. the mountain, therefore, continued to be slowly raised in the air by the materials brought out through this opening. then came the great explosive eruption during which the side of the mountain was blown off to form the great chasm of the val del bove. because of its almost constant activity, mt. etna must have been well known to the ancients, who described some of its most violent eruptions. the following brief notes concerning these eruptions have been taken from lyell. according to diodorus siculus, an eruption that occurred before the trojan war, caused the people living in districts near the mountain to seek new homes. thucididies, the greek historian, states that in the sixth year of the peloponnesian war, which would be about the spring of b. c., a lava stream caused great destruction in the neighborhood of campania, this being the third eruption that had occurred in sicily since it had been settled by the greeks. seneca, during the first century of the christian era, calls the attention of lucullus to the fact that during his time mt. etna had lost so much of its height that it could no longer be seen by boatmen from points at which it had before been readily visible. but passing by these very early eruptions of etna we come to the great eruption of . this eruption was preceded by an earthquake that destroyed many houses in a town situated in the lower part of the forest zone, about twenty-five miles below the summit of the mountain, and ten miles from the sea at catania. during this eruption two deep fissures were opened near catania. from these such quantities of sand and scoriæ were thrown out, that, in the course of three or four months, a double cone was formed feet high, which is now known as monte rosso. but what was most curious was the sudden opening, with a loud crash, of a fissure six feet broad reaching down to unknown depths that extended in a somewhat crooked course to within a mile of the summit of etna. this great fissure was twelve miles in length and emitted a most vivid light. five other parallel fissures of considerable length opened, one after another, throwing out vapor, and emitting bellowing sounds which were heard at a distance of forty miles. these fissures were afterwards filled with molten rock, and in this manner were formed the long dikes of porphyry and other rocks that are seen to be passing through some of the older lavas of mt. etna. [illustration: fig. . mt. etna _from map of state and government_] the great lava streams which flowed down the side of the mountain during this eruption, destroyed fourteen towns and villages, and at length reached catania. a great wall had been raised around this city to prevent the lava from entering it. the molten rock, however, accumulated, until it rose to the top of the wall, which was sixty feet high, and then pouring over it in a fiery cascade, overwhelmed part of the city. it is said that during the first part of its journey, the lava streams moved over thirteen miles in twenty days, or at the rate of feet an hour. beyond this, after the lava had thickened by cooling, it had a velocity of only twenty-two feet per hour. fig. represents a plan of mt. etna reduced from a map by the italian government. during the eruption of , a rent was made in the mountain extending from mount frumento (b in the preceding map) for one and one-half miles, and six cones from to feet in height were formed along the fissure. during the eruption of , great fissures three miles in length were formed in the mountain. there exists on the slopes of mt. etna vast subterranean grottoes formed by the sudden conversion into steam of great quantities of water that were overwhelmed by the molten mass. these immense volumes of steam produced enormous bubbles in the molten lava. when the lava hardened irregular grottoes were left. lyell describes one of these as follows: "near nicolosi, not far from monte rosso, one of these great openings may be seen, called the _fossa della palomba_, feet in circumference at its mouth and seventy-eight deep. after reaching the bottom of this, we enter another dark cavity, and then others in succession, sometimes descending precipices by means of ladders. at length, the vaults terminate in a great gallery ninety feet long, and from fifteen to fifty broad, beyond which there is still a passage, never yet explored, so that the extent of these caverns remains unknown. the walls and roofs of these great vaults are composed of rough bristling scoriæ of the most fantastic forms." besides the eruptions mentioned there have been many others, such as those of , , and . the last of these was greater than any eruption except that of . it began in august, , and continued until may, , and was remarkable for the immense quantity of lava thrown out. [illustration: fig. . stromboli, viewed from the northwest, april, ] we come now to the volcano of stromboli. stromboli, one of the lipari islands, is situated about sixteen miles west of the straits of messina. its general appearance is shown in fig. . the form of the mountain is that of an irregular four-sided pyramid, which rises about , feet above the level of the mediterranean, and stands on the bottom of the sea in water about , feet deep. if you carefully examine the appearance of stromboli, as shown in the preceding figure, you will notice that the flat cloud which hangs over the island is made up of a number of globular masses of vapor, formed during the peculiar action of the volcano. when examined by night stromboli presents a still more curious appearance. since the mountain stands alone, its height permits it to be seen readily at sea for distances of at least a hundred miles. at night a curious glow of red light may be seen on the lower surfaces of the cloud. this light is not continuous, but increases in intensity from a faint glow to a fairly bright red light, then gradually decreases, and finally dies away completely. after awhile the light again appears, again gradually decreases, and disappears, and this continues until the rising sun prevents the red glow from being any longer visible. stromboli, therefore, acts not unlike the flashing lighthouses so common on the sea coasts of all parts of the world. indeed, it is actually used by sailors in the mediterranean for the purpose of showing them their direction. for this reason stromboli is commonly called "the lighthouse of the mediterranean." as judd remarks, from whom much of the information concerning some of the volcanic districts of the mediterranean has been obtained, the flashing light of stromboli differs from that of the ordinary flashing light in two important respects; viz., in the intervals that elapse between the successive flashes, and in the intensity of the light emitted. as you know, it is necessary that the different lighthouses placed near one another on a coast must have their lights of such a nature that they can be readily distinguished. in order to do this, the flashing light has been devised. in flashing lighthouses, the lights only appear at intervals, one lighthouse being distinguished from another in its neighborhood by the intervals between successive flashes, or, sometimes, indeed, by the color of some of the flashes. now, in the case of stromboli, the intervals between the successive glowings of the red lights are very irregular, varying between one and twenty flashes per second. moreover, the intensity of the light also varies greatly from time to time. you naturally inquire as to the cause of these flashes of light that are emitted by stromboli. if, as judd suggests, you should climb to the summit of the mountain, during the daytime, and look down the inside of the crater, you could see its black slag bottom crossed by many cracks and fissures. from most of the smaller fissures the vapor of water is quietly escaping. this vapor rises in the air in which it soon disappears. there are, however, larger cracks on the bottom of the crater from which, at more or less regular intervals, masses of steam are emitted with loud snorting puffs not unlike those produced by a locomotive. from some of the openings molten matter is seen slowly oozing out, collecting in parts of the crater and moving up and down in a heaving motion. every now and then a bubble is formed on the surface of this liquid. the bubble swells to a gigantic size, and suddenly bursts. the steam it contained escapes, carrying fragments of scum which are thrown high into the air. the masses of steam, formed below the surface of the sticky, boiling, lava, in endeavoring to escape, force their way through the mass, blow huge bubbles, which, on bursting, produce the roaring sounds that are heard, and throwing great columns of vapor in the air, produce the rounded masses of clouds you can see floating high up in the air over the mountain. at the same time the scum is partially removed from the red hot surface, its light illumines the lower surface of the overhanging cloud, which flings it back again to the earth. with the bursting of each bubble, and the clearing of the scum from the surface of the red hot mass, the light begins, increases in intensity, and then as the scum again begins to collect on the surface, decreases, and finally disappears, and not until the bursting of the next bubble is it again visible. but let us make a study of some of the peculiarities of vulcano, another of the lipari islands, which lies north of sicily. vulcano affords a curious example of a volcano that has been harnessed by man, or made to do work for him. all volcanoes bring from inside of the earth different kinds of chemical substances, in the form of vapors, gases, or molten materials. now, these materials acting on one another, produce chemical substances some of which, such as sal ammoniac, sulphur, and boracic acid, possess commercial value. this is especially true in the case of vulcano, and since the eruptions are not generally violent, a chemical works has actually been erected by a scotch firm on the side of the mountain, where the materials are collected from the crevices. this effort to harness a volcano was for a time so successful that the same people contemplated the building of great leaden chambers over the principal fissure at the bottom of the crater, so that the large volumes of ejected vapors might be condensed and collected. but vulcano, like all other volcanoes, could not be relied on continually to keep the peace. one day it suddenly burst forth more fiercely than usual, so that the workmen were compelled to abandon the factory and fly down the mountain for their lives, but not, however, before some of them were severely injured by the explosions. vulcano is an instance of a volcano in an almost exhausted or dormant condition. it has had, however, many eruptions during the past few centuries, some of which have been very violent, for example, that of , and that of . there still remains to be considered the volcanic region of the santorin group of the grecian archipelago. the island of santorin or thera, is the southernmost of the cyclades. it is an exceedingly curious island, being a submerged volcano, with most of the top of the crater remaining above the waters, so that the entire island has the shape of an irregular circle or crescent broken at several points. its formation is, probably, due to the gradual sinking of a volcanic mountain until its crater has been almost completely submerged, only the higher parts of the edges of the crater being left above the surface of the waters. suppose, for example, a mountain like vesuvius at the time the crater somma existed, was sunk below the level of the mediterranean until only the highest parts of the crater remained above the waters. if, now, one or more volcanic eruptions occurred, producing craters or volcanic islands inside the submerged rim, you would have a condition of affairs seen in the island of santorin. chapter vii orizaba, popocatepetl, ixtaccihuatl, and other volcanoes of mexico while some of the volcanoes of mexico are still in an active condition, most of them are either only slightly active or are dormant or extinct. humboldt, the celebrated traveller and geographer, states that there are only four active volcanic mountains in mexico; namely, popocatepetl, tuxtula, colima, and jorullo. but there are many others, among which may be mentioned orizaba, ixtaccihuatl, xinantecatl, tuxtula, cofre de perote, and colima. of course, you can understand that, since extinct volcanoes may at any time become active, in parts of the world where communication with the interior is not good, many volcanic mountains that have been regarded as extinct may have broken out temporarily, during historical times, without their eruptions having been recorded. it was at one time thought that popocatepetl was the highest mountain in north america. more recent measurements, however, have shown that there are at least three other mountains in this part of the world, that are much higher. one of these is the active volcano of orizaba that we will now briefly describe. [illustration: fig. . mexico and central america] orizaba is situated in the north central part of mexico, about seventy-five miles west of vera cruz. its ancient aztec name was cittaltepetl, or _star mountain_. the height of the mountain is , feet. like all high tropical mountains whose summits are snow-clad, one would pass through the same changes in climate, in going from its base to its summit, as in going along the earth's surface from the equator to the poles. near the base of the mountain will be found a tropical climate, above that a temperate climate, while in still higher regions, the climate of the arctic region. according to russell, from whose work on the volcanoes of north america much of the information concerning the volcanoes of mexico and central america has been condensed, orizaba has three craters on its summit. the last recorded eruption took place about the middle of the eighteenth century. the mountain is now in a dormant or extinct condition, as may be seen from the fact that its three craters are for the greater part filled with snow. orizaba, like etna, and many other volcanoes, has deep fissures extending through its sides. through these, lava streams have flowed during times when it was active. there are also found on the slopes of this mountain many cones of a type known as _parasitic cones_. these cones are not caused by materials that have been brought to the surface during an eruption, but have been formed by the steam passing through lava streams that have come out of the crater during other eruptions. popocatepetl, or, as the word means, _the smoking mountain_, is the second highest mountain in mexico. according to recent measurements made by the mexican government, its height is , feet. popocatepetl is situated on the edge of the great plateau of mexico, forty miles southeast of the city of mexico. it is a conical mountain, and is a magnificent object when seen from the city of mexico, rising, as it does, fully , feet from the elevation of the city, while on the east it towers for nearly , feet above the level of the sea. this splendid mountain is poetically described by russell: "seen from the basal plains, it sweeps up in one grand curve to nearly its full height,--a collossus of three and a quarter miles in elevation, white with everlasting frost on its summit, and bathed in the green of palms, bananas, oranges, and mangoes, at its base. evergreen oaks and pines encircle its middle height, and above them, before the ice itself is reached, occur broad areas of loose sand into which the lavas have been changed by weathering. soft wreaths of sulphurous vapor may at times be seen curling over the crest of the summit crater,--gentle reminders that the days of volcanic activity are not yet necessarily over." popocatepetl takes its name, _the smoking mountain_ from the fact that gases and vapor are continually being emitted from its summit crater. it has a conical peak with a depression or crater on its summit. the bottom of the crater is crossed by fissures from which small quantities of steam escape, not, however, sufficient to melt all the snow which covers the slopes of the mountain to a depth of from eight to ten feet. a small lake of hot water has collected in the crater from the water derived from the melting snow. this water, sinking through the porous materials in the cone, is the source of a great number of large hot springs that occur around the base of the mountain. reclus states that the first to climb to the top of popocatepetl was one of cortez' officers, . another snow-capped volcano, which rising from the plain of mexico is in clear view of the city, is ixtaccihuatl (ets-tak'-se-wat-el), or as the word means in the ancient aztec, _the white woman_. this mountain, as measured by heilprin, is , feet in height. ixtaccihuatl is now in so dormant a condition that many who have climbed to the top assert that it is not a volcano at all, since they find no crater on its summit. nor are there any signs of volcanic heat, the summit being snow clad during summer. the conical form of the mountain, however, and the fact that the entire mountain is formed of volcanic rocks, show beyond doubt that it is an extinct volcano, whose crater has most probably been completely filled in by the washing away of its sides. xinantecatl is another extinct volcanic mountain situated about forty miles southwest of the city of mexico. it is about , feet high. its name means in the ancient aztec language, _the naked lord_. it is also sometimes known as the nevado de toluca, or _the snow of toluca_. on the top of the peak are two craters filled with lakes of fresh water. russell states that the larger of these lakes is about thirty feet in depth and contain a peculiar species of fish. tuxtula is another volcano of mexico, situated on the western coast of the gulf of mexico, about eighty miles southeast of vera cruz. it was an active volcano in , when it threw out molten lava. it then became dormant until march, , when its long rest was broken by one of the grandest explosive eruptions of modern times. this eruption rivalled in energy the great explosive eruption which blew off the summit of coseguina, in central america, in . as is common in the case of explosive eruptions, volcanic dust and scoriæ were blown high into the air, and, being carried by the winds, fell on the roofs of houses and on the land at a distance of miles. there have been a number of less violent eruptions of tuxtula since . tuxtula is a comparatively low mountain, being only , feet high, because much of the mountain was blown away by the eruption of . as russell points out, it is not safe to infer that because an eroded mountain is not lofty it cannot be young or energetic, since the very energy of some of its eruptions may, as in the case of tuxtula, blow away a large part of the mountain. a low mountain, with an unusually large crater, generally means a mountain that has been visited by a great explosive eruption. another extinct volcano known as the cofre de perote is situated on the eastern coast of mexico, east of ixtaccihuatl, about thirty miles north of orizaba. it takes its name cofre de perote which means the coffin of perote, from its peculiar box-like shape. it was called in the aztec language "nauhcampatepetl," or the _four-ridged mountain_. cofre de perote is in a dormant or extinct condition. we will conclude this brief description of the volcanoes of mexico with the volcano of colima, a mountain about , feet high situated on the western coast of mexico. colima has been active of recent years, eruptions having occurred in , , , and . during these eruptions lava escaped from lateral openings in the sides of the mountain, these openings being termed by the natives the _sons of colima_. chapter viii coseguina and other volcanoes of central america central america has a great number of volcanoes extending along nearly all its western coast, or on the pacific side of the country. central america consists of a high plain or table-land sloping gently towards the northeast, but terminating abruptly on the southwest. in the opinion of geologists this table-land consists of the surface of a huge tilted block of the earth's crust, or, perhaps, more probably, of a series of such blocks, that are limited on the southwest by a narrow belt of intersecting fractures. it is in these fractures that scores of volcanoes are situated, together with active craters, solfataras, and hot springs. the volcanoes are mainly of the vesuvian type. there are so many volcanoes in this part of the world that it will be possible to describe but a few of them. we will begin with the volcano of coseguina, situated on the pacific coast of nicaragua. its appearance is that of a conical mountain with the top cut off, and suggests that it is most probably an explosive volcano which has had the top blown away during some of its great eruptions. coseguina is celebrated by reason of its tremendous eruption of . before the still more tremendous explosive eruption of krakatoa in , described in the first two chapters of this book, coseguina shared with sombawa, on the island of sumatra, as being the foremost of explosive volcanoes. it had been estimated that before its eruption of , coseguina had a height of perhaps , feet, but so much of it was blown away by this eruption that it now is a little less than , feet. the following description of the great eruption of coseguina in has been condensed from an account prepared by squier, published in . you will note in reading this brief account how closely many of the phenomena resemble those that occurred during the eruption of krakatoa in . the eruption of coseguina was heralded on the morning of january th, , by several loud explosions that were heard for a distance of some miles around the crater of the volcano. then followed an ink black cloud formed directly over the mountain, which gradually spread on all sides shutting off the light of the sun, except for a sickly yellowish light. fine sand was thrown from this cloud, which made it both difficult and painful to breathe. for two whole days the cloud continued to grow denser, the explosions louder and more frequent, and the rain of sand thicker. on the third day the explosions were strongest and the darkness greatest. the amount of sand that fell from the cloud was so great that people left their houses, fearing the roofs would be crushed in by the great weight. this sand fell in large quantities over an area more than , miles in diameter, or, quoting the language of squier: "the noise of the explosions was heard nearly as far" ( , miles). "and the superintendent of belize, eight hundred miles distant, mustered his troops, under the impression that there was a naval action off the harbor. all nature seemed overawed; the birds deserted the air, and the wild beasts their fastnesses, crouching, terror-stricken and harmless, in the dwellings of men. the people for a hundred leagues grouped, dumb with terror, amidst the thick darkness, bearing crosses on their shoulders and stones on their heads in penitential abasement and dismay. many believed that the day of doom had come, and crowded in the tottering churches, where, in the pauses of the explosions, the voices of the priests were heard in solemn invocation to heaven. the brightest lights were invisible at the distance of a few feet; and to heighten the terror of the scene, occasional lightnings traversed the darkness, shedding a lurid glare over the earth. this continued for forty-three hours, and then gradually passed away." it appears that the eruption of coseguina was followed by violent earthquake shocks and other evidences of volcanic energy over extended regions. for example, there were fearful earthquakes along the andes, the worst of which occurred on february th, and continued at the rate of three or four a day up to march th, and, less frequently, to march th. it was during one of these earthquakes that the city of concepcion, chile, was so completely destroyed, that but a single house remained. the same brilliant sunsets and sunrises occurred in different parts of the world after the eruption of coseguina, due to the presence of large quantities of volcanic dust that followed the great eruption of krakatoa. the cause of this great explosive eruption of coseguina was most probably the same as that which is believed to have caused the eruption of krakatoa, namely, a large volume of water suddenly gaining access to a mass of liquid lava. volcán del fuego is another of the many volcanoes of central america. it is situated as one of a group of volcanoes on the highest summit of the isthmus. this volcanic mountain has a regular cone with regular slopes on all sides, except on the north, where a table-like projection, about , feet below the summit, is all that remains of a vast cone, the summit of which was blown away, according to russell, in prehistoric times, just as was the crater of somma on vesuvius. there have been in central america, since the time of the spanish conquest, some fifty volcanic eruptions sufficiently great to have been recorded. some idea of the activity of fuego during this time may be had from the fact that of all these eruptions some twenty were those of fuego. at the present time, however, the volcano is dormant and apparently almost extinct. the recorded eruptions of fuego are nearly all of the explosive type. among the most violent were those that occurred during , , and . during , , and , there were eruptions nearly every month, the most terrible being near christmas day in . other memorable eruptions occurred in , , , and , and at other dates down to august th, , from which date to the present time the volcano has been quiet. we will conclude this brief description of the volcanoes of central america with that of volcán de agua, or, as the word means, _the water volcano_. it is situated in guatemala near the coast, and is one of the mountains that occupies the plateau on which fuego is situated. the volcán de agua is one of the most remarkable volcanoes in central america, standing, as it does, nearly alone, and rising to an elevation of , metres ( , ft.), above the level of the sea. it has been extinct for a long time. it has been supposed by some, from its name, that this is a volcano that throws out water. others believe that the name comes from the water produced by the melting of the snow that is collected on the sides of the mountain. now there almost always escapes from the craters of volcanoes during violent eruptions immense quantities of water vapor, which, condensing, fall as vast showers of rain that often deluge the surrounding country. in snow-clad mountains, the escape of lava is often attended by floods caused by the rapid melting of the snow. the water volcano did not, however, take its name from either of these facts, but rather because at the time of the spanish invasion, the crater of the mountain was occupied by a large lake, and that during an earthquake in the wall of the crater was broken, when the lake was poured as an immense stream of water down the side of the mountain, overwhelming a village which was situated on this slope. that this was the correct origin of the same may be seen from the fact that the crater at the present time still shows the remains of its former lake basin, and that on the sides of the broken rim an immense ravine can be seen through which the water poured down on the village below. daubeny describes this volcano as follows: "the volcán de agua (water-volcano) is of enormous height, being covered with eternal snow, in the latitude of °. captain basil hall estimates it at more than , feet, but a recent traveller states it at , . it has the form of a blunted cone clothed with perpetual verdure to its summit. the crater is from forty to sixty yards in depth, and about in diameter,--the sides and bottom strewed with masses of rock, apparently showing the effects of boiling water or of fire. "by a deluge of water from this volcano in , the original city of guatemala was overwhelmed; and the next built, called the old city, _la antiqua_, was ruined by an earthquake in . the present capital is situated at a distance of eight leagues from the mountain." another volcano in this part of the country is described by daubeny as follows: "massaya, near the lake of that name, was one of the most active vents at the time of the first discovery of the country. its flames were visible twenty-five miles off. its crater was only twenty or thirty paces in diameter; but the melted lava 'seethed and rolled in waves as high as towers.' a story is told of a dominican who imagined the fluid lava was melted gold, and descended into the crater with an iron ladle to carry some away; but the ladle, it is said, melted, and the monk escaped with difficulty." chapter ix the volcanic mountains of south america the volcanoes of south america are limited to the andes mountain system that stretches like a huge wall along the entire western side of the continent. the names of the more important of these volcanoes are marked on the map of south america, shown in fig. . as will be seen, this huge mountain wall reaches from patagonia on the south to the isthmus of panama on the north. the arrangement of the volcanoes in south america is of the linear type. the craters follow one another in more or less straight lines, or are situated along the lines of great fissures that lie near the ocean. you must not, however, suppose that there is a continuous chain of active volcanic mountains from the isthmus of panama to the southern part of the continent. according to lyell, from lat. ° n., or from the north of quito, to lat. ° s. or south of chile, a total distance including ° of latitude, there is a succession of districts with active and extinct volcanoes, or at least with volcanoes that have been quiet during the last three centuries. [illustration: fig. . south america] lyell traces the volcanoes of south america as follows: "the principal line of active vents which have been seen in eruption in the andes extends from lat. ° ' s., ... to lat. ° s.; to these thirteen degrees of latitude succeed more than eight degrees, in which no recent volcanic eruptions have been observed. we then come to the volcanoes of bolivia and peru, extending six degrees from s. to n., or from lat. ° s. to lat. ° s. between the peruvian volcanoes and those of quito another space intervenes of no less than fourteen degrees of latitude, in which there is said to be but few active volcanoes as far as is yet known. the volcanoes of quito then succeed, beginning about geographical miles south of the equator, and continuing for about miles north of it, when there occurs another undisturbed region of more than six degrees of latitude, after which we arrive at the volcanoes of guatemala, or central america, north of the isthmus of panama." of course, you must not understand that there are no extinct volcanoes in these gaps. on the contrary, according to daubeny, we find, beginning on the north in the united states of colombia, the lofty volcano of tolima. according to daubeny's book published in , tolima was then constantly emitting steam and sulphur gases from its summit. tolima is situated in the easternmost of the three mountain ranges that extend through this section of the country. it is, therefore, at a comparatively great distance from the ocean. tolima was in eruption in . it again burst out in . coming now to ecuador we find that this, the smallest of the south american republics, contains numerous great volcanic mountains. some of the principal volcanic mountains are chimborazo, , feet above the sea; antisana, , feet; cotopaxi, , feet; pichincha ( , feet in , daubeny), el altar, , feet. these all lie in south america on the plateau of quito. as baron alexander von humboldt has pointed out, the volcanic mountains of quito are arranged in two parallel chains that extend side by side for a distance of over miles north into the state of colombia, including between them the high plateaus of quito and lacumbia. according to whymper, however, who has recently studied this part of south america, there is a succession of basins between the mountains, but there is no such thing as a single valley in the interior of ecuador. the extinct volcanoes of cayamba, antisana, and chimborazo are the most important. on all three mountains there are old lava streams on their sides. although no craters can be seen on their summits, yet it is almost certain they once had craters. there is plenty of room on the summit of antisana for a cone as great as that of cotopaxi. whymper is of the opinion that the snow domes that form the summit of chimborazo were at one time two of the highest points of the rim of the old crater. nearly due south of quito is the great volcanic cone of el altar. like all the peaks of this high plateau, el altar rises to a great height above the sea, being at the present time , feet above the sea. this mountain has an enormous crater that appears to be dormant or extinct, and is covered with snow. according to the traditions of indians, el altar, or, as they call it, _capac urcu_ or _the chief_, was the highest mountain near the equator, being much higher than chimborazo. but during a prodigious eruption that occurred before the discovery of america, and continued uninterruptedly for eight years, the height of the mountain was considerably reduced. according to boussingault, the fragments of the cone of this celebrated mountain are now spread for great distances around the mountain on the surrounding lowlands. pichincha in ecuador, an extinct volcano, is situated almost immediately on the equator. it has a height as measured by whymper by the barometer, of , feet above the pacific. the summit is covered by blocks of pumice. several species of lichens are found at this elevation. according to daubeny, pichincha was extinct prior to , when it became active. there were also eruptions in , , and . it was also in activity during . cayamba, another volcanic mountain of ecuador, lies to the east of pichincha, a short distance north of the equator. its height is , feet. it is nearly extinct. cotopaxi, , feet, is another volcanic mountain of the high plateau of quito. cotopaxi is still active. its slopes are covered with snow down to a height of about , feet. between the lower edge of this snow line and the lower slopes of the mountain, there lies a zone of naked rock. according to whymper, the eruption of cotopaxi, in , was preceded by an unusual degree of activity in the earlier parts of the year. this, however, did not cause any alarm until june th, , when, shortly after midday, an eruption, attended by tremendous subterranean roars, began, and an immense black column shot up into the air for about twice the height of the cone. this eruption was clearly visible at quito, for the wind blew the ashes towards the pacific. at this time the summit had not changed its appearance, but towards : a. m., on the next day, another enormous column of ashes rose from the crater. the ashes and cinders were first carried due north by the winds, and then, spreading out in all directions, were subsequently distributed through the air all over the country. at quito, as early as a. m., the sky assumed the appearance it generally has at twilight, and the darkness increased until midday, when it became as dark as at midnight. indeed, it was so dark that one could not see his hand before his face. during this eruption, as is very common in the eruptions of the snow-clad mountains of south america, a flood of water, due to the rapid melting of the snow and ice on the summit, rushed down the mountain slopes at o'clock a. m., on the th of the month, almost immediately after the appearance of a stream of lava that began to flow down the mountain. in a few moments the mountain was completely shut off from view by immense columns of steam and smoke. at first, a low, moaning sound was heard, which rapidly increased to a roar, when a deluge of mud, mingled with huge blocks of ice and stones, swept down the mountain, leaving a desert in its path. it is estimated that at some places this stream moved with a velocity of fifty miles per hour. the general appearance of cotopaxi is shown in the accompanying reproduction from the painting by frederick e. church in the lenox library, new york. according to whymper, who made an ascent of cotopaxi in , the crater on the summit has the form of an immense amphitheatre, , feet across from north to south, and , feet from east to west. its crest is irregular and notched. the crater is surrounded by perpendicular cliffs. the western side of the volcano is irregular. barometric measurements gave the height of this volcano at , feet. its height as taken by la condamine, during the early parts of the last century, was , feet, so that, according to whymper, assuming as would seem probable, that this difference in height has not all been due to errors in measurements, the volcano has grown or increased in height during the last century and a half. chimborazo, , feet, is another lofty mountain on the plateau of quito. this volcano is situated in lat. ° ' s., and is not at the present time in an active condition. it is, however, formed entirely of volcanic material. its upper portions are covered with a layer of snow to a level of some , feet below the summit. [illustration: cotopaxi _from a painting by frederick e. church in the lenox collection of the new york public library. by permission_] chimborazo has an enormous volcanic summit, which, when seen from the pacific, when the air is especially clear after the long rains of winter, is a most splendid sight. whymper, who ascended the mountain, says: "when the transparency of the air is increased and its enormous circular summit is seen projected upon the deep azure of blue of the equatorial sky, it represents a magnificent sight. the great rarity of the air through which the top of the andes is seen adds much to the splendor." whymper says, that as far as records are concerned, there have been no eruptions of chimborazo, which has apparently been an extinct volcano for many years. its crater has been completely buried by a thick cap of ice on its summit, while what lava streams exist on the mountain are either covered by large glaciers, or have been removed by erosion, or hidden by vegetation. chimborazo possesses less of the conical outline than cotopaxi. there are steep cliffs towards the summit that have been named by whymper "the northern and southern walls." they seem to him to have been formed by the violent upheavals of the explosive eruptions that have blown away portions of the cone. there are other volcanoes in this district, but the above are all we have space for describing. according to lyell, the volcano of rancagua, in chile, lat. ° ' s., is continually throwing up ashes and vapors like stromboli. indeed, a year seldom passes in chile without some earthquake shocks. of these shocks those which came from the side nearest the sea are most violent. the town of copiapo was laid waste by these shocks during the years , , and , in both instances after intervals of twenty-three years. since the volcanic mountains of south america are snow-covered the occurrences of volcanic eruptions are apt to be attended by great floods caused by the rapid melting of the snow, as well as sometimes by the breaking of huge subterranean cavities that are filled with water. according to lyell, the volcanoes of peru rise from a plateau from , to , feet above the sea. one of the principal volcanoes of peru is arequipa, whose summit is , feet above the level of the sea. the mountain takes its name from the city of arequipa, which is situated not far from its base. it is an active volcano. another volcano, viejo, is found in lat. ° ' s. according to lyell, there are active vents extending through chile to the island of chiloe to lat. ° n. aconcagua, west of valparaiso, in lat. ° ' s., , feet in height, the highest mountain in south america, is still in an active condition. according to scrope, when the city of mendoza was destroyed by an earthquake, that killed , people, in march, , it is probable that aconcagua was in eruption. there are many other active volcanoes in chile, extending as far south as the volcanoes of patagonia, north of the straits of magellan as well as others of tierra del fuego. chapter x volcanoes of the united states for some readers this may be a surprising chapter heading, for it is a general impression that there are no volcanoes in the united states. it is true that practically all of the volcanoes of this country are dormant or extinct. they have, however, at one time been exceedingly active, and, if reports are correct, some of them were active during comparatively recent times. nearly all of the volcanoes of the united states lie west of the meridian of denver. these volcanoes belong to two distinct types, either the vesuvian type with built up cones, or the plateau or fissure type already referred to. the following brief description of the volcanoes of the united states has been collated, for the greater part, from wallace's excellent book on the volcanoes of north america. crossing the united states on the southern pacific railroad one's attention is caught, in arizona, by a magnificent group of mountains known as the san francisco mountains. the highest peak of these mountains reaches , feet above the level of the sea, and , feet above the surface of the plateau on which the mountains stand. [illustration: fig. . the united states] according to g. k. gilbert, the san francisco mountain group is formed of a variety of lava known as trachyte, that is of comparatively recent ejection, possibly of a geological age called the tertiary. the lava forming the mountains escaped through a number of crater cones, some of which can still be seen in the neighborhood. some of these craters are now in almost as perfect a condition as the day they were formed. indeed, to one looking at them from a neighboring elevation, they appear so fresh, and so little affected by the climate, that one might almost believe that the lava had just flowed out of the craters, and has not yet hardened. nevertheless, geologists are sure they have been formed long before man appeared on the earth. in one of these craters a lake of fresh water has collected. another extinct volcano of the united states is mt. taylor in new mexico, nearly east of the san francisco mountains. this mountain rises from the surface of a high table-land, or, as it is called in this part of the world, a _mesa_. the surface of the plateau is covered with a thick lava stream from which mt. taylor rises to a height of , feet above the level of the ocean. this mesa, or table-land, is forty-seven miles in length from northwest to southeast, and about twenty-three miles in breadth. its general elevation is about , feet. the plateau rises about , feet above the surface of the level land that surrounds it. all these , feet have been removed by erosion. the table-land from which mt. taylor rises has not been eroded by the action of the rain, rivers, and other weathering agencies like the surface of the country surrounding it, because of a covering of lava that has been spread over its surface to a depth of about feet. mt. taylor is formed almost entirely of lava that has escaped through a single opening and has built up a high cone around it. the volcano is now quite extinct, so that the original form of the mountain has been greatly changed by erosion. you will remember, when we were discussing the general subject of volcanoes, in the beginning of this book, that we spoke of volcanic mountains being bottled up after an eruption, by the hardening of the lava which remained in the crater and the tube that connects the crater with the place from which the lava had been derived. we then spoke of this hardened mass being known as a _volcanic plug_, or stopper, explaining how the volcano could never again erupt through its old crater unless it could develop sufficient force to blow out or remove this stopper. now besides the crater at the top of mt. taylor there were several others in the eroded region surrounding the mesa, or high table-land, from which mt. taylor rises. when, therefore, the erosion which removed the , feet of rocks on all portions of the old mesa that were not protected by the coating of lava, these old mountain plugs were too hard to be worn away or eroded, and were, therefore, left projecting into the air like vast pyramids. if you should ever visit mt. taylor and should go to the eastern border of this mesa, and look over the eroded plain, you would see in the lowlands a part of the places from which the , feet of matter have been slowly eroded. dutton describes the beautiful panorama that is to be seen as follows: "the edge of the mesa suddenly descends by a succession of ledges and slopes, nearly , feet into the rugged and highly diversified valley-plain below. the country beneath is a medley of low cliffs and bluffs, showing the browns and pale yellows of the cretaceous sandstones and shales. out of this confused patchwork of bright colors rise several objects of remarkable aspect. they are apparently inaccessible eyries of black rock, and at a rough guess, by comparison with the known altitudes of surrounding objects, their heights above the mean level of the adjoining plain may range from to , feet. the blackness of their shade may be exaggerated by contrast with the brilliant colors of the rocks and soil out of which they rise, but their forms are even more striking." these black piles are the _necks_ or lava plugs of extinct volcanoes. they rise above the level of the plain because, being harder than the surrounding rocks, they have resisted erosion. in some cases these necks or plugs have been converted by shrinkage, on cooling, into beautiful columns, somewhat of the type of the basaltic columns of the giant's causeway. it would be difficult to count the number of volcanic necks that can be seen near the edge of the mesa. one's attention is at once attracted to some dozen of these piles, which are especially striking on account of their great size, and ominous black color, but the number is by no means limited to this dozen. there are hundreds of them. fig. gives some idea of a part of the view from the edge of the mesa, and fig. the appearance of two of these volcanic necks. but besides high volcanic mountains such as the san francisco mountains and mt. taylor, there are, in different parts of the united states, to be found fragments of huge craters from which, in the geological past, immense quantities of lava have escaped. in some instances these craters are but fragments of huge craters, that, like the crater of mt. somma, in vesuvius, have been nearly completely blown away by some unrecorded explosion during the far past. [illustration: fig. . panorama from the mesa at the edge of mt. taylor _from u. s. geological survey_] a crater of this type, known as ice springs crater, is situated in the desert valley west of the wahsatch mountains, some miles south of salt lake city, utah. this crater is especially interesting from the fact that it occupies a position on a plain that was formed by the deposition of sediment in an immense lake that covered this part of the united states very long before man lived on the earth. we are alluding to lake bonneville, a lake that existed in a geological time known as the glacial epoch. this lake occupied the territory now filled by the great salt lake of utah, but towards the close of the glacial epoch it was immensely larger than it is now. this can be shown not only by the presence of shore lines, that are clearly marked on the sides of the surrounding mountains, but also by the ancient lake beaches, and deltas, that are common in the district, so that instead of there being the comparatively limited area of great salt lake as marked on the maps of to-day there was a lake that had an area of , square miles, that covered an area on which at least , people dwell. [illustration: fig. . volcanic necks, edge of mesa at mt. taylor _from u. s. geological survey_] a similar lake, known as lake lehontan, existed at the same time, covering large areas in the western parts of nevada. coming now to ice springs craters in utah, we find here three small craters formed of scoriæ and lapilli (volcanic ashes consisting of small angular stony fragments). near them lies a fragment of a much larger crater known as the crescent. in some respects this crater was not unlike the crater of somma that surrounded mt. vesuvius. it was not, however, as large, having a diameter of only , feet. from these craters streams of basalt flowed until they covered considerable areas. a still more recent crater known as tabernacle crater is situated four miles south of the ice springs crater. tabernacle crater takes its name from the building known in salt lake city as the tabernacle. according to gilbert, this crater was formed at a time when lake bonneville stood at a comparatively low level, or when the water was only from fifty to seventy-five feet above the bottom of the valley on which the crater now stands. at that time an explosive volcanic eruption occurred on the bottom of the lake, and the rim of the crater, built up by this explosion, was gradually pushed above the surface of the lake, so as to shut out its waters. extinct volcanic craters, not unlike those of utah, occur also near ragtown, in nevada, in a district known as the carson valley desert, in one of the broadest areas of what was once lake lahontan. ragtown is twenty-two miles southwest of wadsworth on the central pacific railroad. at the present time there are two circular depressions or volcanic craters filled with pools of strongly alkaline water known as the ragtown pond, or soda lake. the large lake covers an area of - / acres. its greatest diameter is over , feet. without going into a detailed description it will suffice to say that the larger crater probably was destroyed by an explosive volcanic eruption. another intensely alkaline lake that fills an extinct volcanic crater is the mono lake, situated in mono valley in california at the eastern base of the sierra nevadas. it has an area of about square miles. the centre of the lake has two small islands named pacha and negit. immediately south of mono lake are a number of craters that occupy portions of what was once apparently a fissure extending in a general north and south direction. the highest of these craters are in the neighborhood of , feet. but leaving these inconspicuous craters, let us briefly examine some of the higher mountain peaks of the united states that are of volcanic origin. one of the most conspicuous of these is mt. shasta. this mountain is situated in california, at the northern end of the sierra nevadas. it has a height of , feet. it is a snow-clad mountain of a conical form, and is a conspicuous object in the landscape, because it stands alone. mt. shasta is a double-coned mountain. besides the cone on its summit there is a well-developed cone known as shastina on the western side of the mountain, , feet lower than the main summit. there are well-defined lava streams on the slopes of mt. shasta. one of these, which issued from the southern side of the mountain at an elevation of , feet, divided into two streams. one of these streams is twelve miles in length. the other entered the canyon of the sacramento river, thus displacing the water. coming now to the cascade mountains, in oregon and washington, we will find in them a number of giant peaks of volcanic origin. the most important of these are in regular order from south to north, as follows: mt. pitt, , feet; mt. mazana, , ; mt. union, , ; mt. scott, , ; three sisters, mt. jefferson, , , and mt. hood, , , in oregon; mt. adams, , ; mt. st. helen's, , ; mt. rainier, , , and mt. baker in washington, , . nearly all these mountains have craters either on their summits or on their sides. they are extinct volcanic mountains, that were, for the most part, thrown up during the tertiary geological period, so that they have all been greatly affected by erosion. one of the most remarkable of the above volcanic mountains is mt. mazana, in oregon. this mountain has on its summit an approximately circular cavity from five to six miles in diameter, that is occupied by a lake of water known as crater lake. this lake is , feet above the level of the sea, and has a depth of , feet. it is surrounded by nearly vertical walls ranging from to , feet deep, so that the vast caldera of which this great depression consists has a depth of at least , feet. mt. pitt, situated about sixty miles north of mt. shasta, in southern oregon, has a regularly shaped volcanic cone, and the remnant of a crater at its summit. the three sisters and mt. jefferson lie to the north of mt. pitt. like the others they are ancient volcanic mountains. but little is accurately known concerning them. mt. hood, , feet high, rises from the crest of the cascade range in northwest oregon, about twenty-five miles south of the columbia river. mt. hood is an exceedingly majestic mountain. at its summit there are only portions of the walls of the original crater. when ascended in , streams of sulphur vapor were escaping from fumaroles on its northeastern slopes, at an elevation of , feet above the sea. mt. adams and mt. st. helen's lie to the north of mt. hood. mt. adams about sixty miles to the north, and beyond this, mt. st. helen's. accurate information concerning the summit of mt. adams is still lacking. mt. st. helen's in washington has more of a conical summit. russell states that according to frontiersmen, st. helen's has been in a state of activity within the past fifty years. a french-canadian asserts that the mountain was in actual eruption during the winter of - , that at this date the light from the volcano was sufficiently bright to enable one to see and pick up a pin in the grass at midnight near his cabin some twenty miles distant. mt. st. helen's was ascended in , when fumaroles were found on the northeast side. mt. rainier in washington is plainly visible from puget sound. it is a most magnificent mountain. the summit has a bowl-shaped crater, of an almost perfectly circular form. the inside of the crater, when last ascended, was filled to within thirty or thirty-five feet of its rim with ice and snow. there was, however, evidences of heat, since numerous jets of steam were seen issuing from its interior rim. mt. baker, washington, is the northernmost of the volcanoes of the cascade mountains, south of the boundary line between the united states and canada. but little is known of this mountain. the summit appears as a conical peak from puget sound, so that its form would seem to show that it is of volcanic origin. according to gibbs, officers of the hudson bay company, as well as the indians, declared that mt. baker was in eruption in , when it broke out at the same time as mt. st. helen's, covering the country with ashes. there are but few volcanoes in the rocky mountains which extend from north to south through the united states at a considerable distance to the east of the sierra nevadas and cascade ranges. the spanish peaks, situated in the southeastern part of colorado about sixty miles south of pueblo, are the remains of ancient volcanoes. two of the most prominent of these peaks rise from , to , feet above the sea. we shall make no effort to attempt to describe the volcanic mountains that may exist in those portions of the rocky mountain ranges or the cascade range lying in canada. comparatively little is known of them, but inasmuch as volcanic activity has been manifested in alaska, it would seem highly improbable, as russell remarks, that volcanoes should suddenly cease at the northern boundaries of the united states and then begin again at the most southern part of alaska. it will be sufficient to say that mt. edgecome, situated on an island in the neighborhood of sitka, is of volcanic origin, and that the aleutian islands, beginning at alaska on the east at the head of cook's inlet, extend westward through the peninsula of alaska to the peninsula of kamtschatka for a distance of nearly , miles. this belt, which is called by russell "the aleutian volcanic belt," contains numerous volcanoes that are known to have been active in historical times. mt. wrangell, on the copper river, miles northeast of the head of cook's inlet, is a lofty volcanic mountain that is said to have been in eruption in , and at the time of last report was still throwing out columns of steam. while much remains to be ascertained about the volcanoes of the aleutian islands, it would appear that there are active volcanoes on twenty-five of these islands, on which some forty-eight craters have been found. eruptions are common in the district. chapter xi the catastrophe of martinique and the volcanic islands of the lesser antilles the west indies island chain consists of two groups of islands; i. e., the greater antilles, including cuba, jamaica, hayti, and porto rico, on the west, and the chain of the lesser antilles on the east. the lesser antilles consists of two parallel chains, the westernmost of which is for the greater part mountainous with peaks several thousand feet in height. all these islands are volcanic. the chain on the east consists of low, calcareous rocks, or rocks consisting largely of lime. in the western chain the islands beginning on the south are, grenada, st. vincent, st. lucia, martinique, dominica, guadeloupe, montserrat, nevis, and st. eustace, while in the calcareous chain are found the tobago, barbadoes, and others. prior to , the greatest volcanic eruption in this part of the world occurred on the island of st. vincent, with the volcano of soufrière. although the forces displayed were exceedingly great, yet they become insignificant when compared with the appalling eruption that took place in martinique only a short time ago; namely, may the th, , when the volcano of mt. pelée, situated on the northwestern part of the island, burst into an eruption so terrible that in destruction of life it far exceeded the eruption of krakatoa, although the amount of energy causing the eruption was much smaller. [illustration: fig. . the lesser antilles] heilprin, in a book called "mt. pelée and the tragedy of martinique," from whom most of the information of this chapter has been obtained, calls attention to the fact that before the eruption of pelée there were plenty of warnings for those intelligent enough to note them. for two or three weeks prior to may th, , the volcanic activity of pelée had been rapidly increasing, the mountain throwing out clouds of ashes and sulphurous vapors from its crater. by april th the sulphurous vapors had so increased in quantity as to make breathing difficult in st. pierre. the ashes fell on the surrounding country and by the d of may had so covered the streets of st. pierre as to stop traffic. three days later, may th, shortly before noon, an avalanche of mud poured down the slopes of the mountain with the rapidity of an express train. these torrents of mud and water deluged the towns and villages in the neighborhood. the activity of mt. pelée increased until the morning of may th, , when, almost at exactly a. m., an eruption occurred, so terrible in its effects that in two minutes the city of st. pierre was almost completely destroyed. st. pierre, the principal town of martinique, is situated on the island of martinique, on the northwestern coast, about ten miles southwest of mt. pelée. st. pierre was settled as far back as . it is situated on an open roadstead without any harbor. that there were many points of resemblance between the position of st. pierre and the destroyed city of pompeii will be recognized as the description of the catastrophe is given. st. pierre was a beautiful city, and formed the natural outlet to one of the richest districts in martinique for the production of sugar cane and cocoa. it contained many fine houses, the homes of planters, wealthy bankers, merchants, and shippers, who, besides their regular houses in the city, had constructed handsome villas on heights on the outskirts of the city. the houses were to a great extent one or two stories in height, and were in many cases surrounded by fine gardens. the city extended along the coast for about two miles. the streets were well lighted. the eruption of mt. pelée on may th, , was of a very unusual character, containing a feature that--with the exception of a volcanic eruption of soufrière, a volcanic mountain on the neighboring island of st. vincent, and an eruption of kilauea in hawaii--so far as i am aware, never before occurred. this was a blast of highly heated air, mingled with white hot or incandescent dust, that swept down the side of the mountain with a velocity of one or two miles per minute, or possibly more. nearly all of the people in st. pierre were killed. from the appearance of the bodies it seemed that death was practically instantaneous, and was due either to scorching or burning, or asphyxiation by the breathing of highly heated air. the number of people so killed, including almost the entire population of st. pierre, as well as a number of adjoining settlements, was not less than , . the zone of absolute destruction was limited to an area the extent of which did not greatly exceed eight or nine square miles. on the outskirts of this zone the destruction, though considerable, was less complete. there was almost an entire absence of great earthquake shocks during the eruption. following the terrible eruption of may th were a number of less violent eruptions on may th, th, june th, july th, and august st. according to heilprin these eruptions were of the same character as that of may th. there has been considerable discussion as to the exact causes of the tornadic incandescent blast that caused the awful destruction of life. without entering this discussion it is sufficient to say that it is now generally considered that the blast consisted of highly heated air, and super-heated steam loaded with great quantities of finely divided red hot or even white hot dust particles. while, perhaps, the force producing the awful eruption of mt. pelée was greatly excelled in the case of many other volcanic eruptions; such as papandayang, in ; asamayama, in ; skaptar jökul, in ; tomboro, in ; coseguina, in ; and krakatoa, in ; yet, in the words of heilprin, "in intensity and swiftness of its death-dealing blast ... the eruption of may th, and of later dates, stands unique in records of volcanic manifestations." while the amount of ashes that accompanied the blast of white hot steam and air was comparatively small, yet during the time between this and the subsequent eruptions, the amount of ashes that were thrown from the surface of mt. pelée was exceedingly great. according to russell, in a paper on the volcanic eruptions of martinique and st. vincent, in , the amount of ashes and solid matter generally thrown out from the crater of mt. pelée would be equal to , , cubic feet every minute, or one and a half times the sediments discharged by the mississippi in the course of a whole year. according to heilprin, however, the actual amount of dust thrown from the crater of mt. pelée was, probably, times greater than the amount discharged by the mississippi river in the course of a year, and, consequently, considerably greater than that of all the rivers of the world combined, or, as he says: "mont pelée has now been in a condition of forceful activity for upwards of two hundred days; can we assume that during this time it may have thrown out a mass of material whose cubical contents are hardly less than a quarter of the area of martinique as it now appears above the waters? one is, indeed, almost appalled by the magnitude of this work, and yet the work may even be very much greater than is here stated. we ask ourselves the questions, what becomes of the void that is being formed in the interior? what form of new catastrophe does it invite? there can be no answer to a question of this kind--except in the future happening that may be associated with this special condition. but geologists must take count of the force as being one of greatest potential energy, whose relation to the modelling and the shaping of the destinies of the globe is of far greater significance than has generally been conceived." a curious circumstance connected with the eruption of mt. pelée was the most pronounced electric and magnetic disturbances. moreover, as in the case of the eruption of krakatoa, there were the same after glows or red sunsets and sunrises due to the presence of fine volcanic dust in the higher regions of the air. these phenomena were observed over widely separated areas. it appears that this great eruption in martinique was preceded by severe earthquakes in the northern part of south america, especially in colombia and venezuela. the most marked was the great earthquake which on april th destroyed the city of guatamaula; this was, perhaps, the most destructive earthquake that has occurred in the western hemisphere since the great earthquake of , that destroyed the city of caracas. indeed, professor milne suggests that it was this earthquake that brought about the eruption of mt. pelée. soufrière, on the island of st. vincent, had a great eruption on may th, , one day before the awful eruption of mt. pelée. no lava flowed during this eruption. there were, however, great discharges of mud, due to a lake that before the eruption filled the top of a depression known as the old crater which lay southwest of a new crater, or the crater that was formed during the eruption of . the old crater was nine-tenths of a mile across from east to west, and eight-tenths of a mile from north to south. the depth to the crater floor was from , to , feet. the surface of the new and shallow boiling lake which occupied the deepest part of the floor during the latter part of may, and from june to august, was estimated to be only , feet above the level of the sea. the sheet of water that occupied it before the eruption being several hundred feet higher. soufrière did not fail to give warnings of its coming eruption. rumblings were heard two days before the explosion. on may th, , fishermen who crossed the lake noticed that the water was disturbed and agitated. on the tuesday following, may th, great clouds were thrown out during the afternoon, and the volcano was illumined by a reddish glare of fire. the first explosion was heard shortly before two o'clock on the following day and the volcano burst into activity. the explosions, together with great discharges of pumice, ashes, and boulders, followed one another rapidly. a column of steam was shot up into the air for a height of , feet. the severest paroxysm came shortly after ten a. m., and was succeeded by others nearly as violent during the next few hours. by this time a reddish curtain of clouds nearly shut out the island from view, and rapidly advanced over the land and descended on the sea. this eruption caused a loss of life of about , . this eruption of mt. soufrière was accompanied by the same tornadic blast of glowing air. there was not, however, any single blast quite as severe as that which attended the eruption of pelée on may th, . chapter xii some other noted volcanic mountains since the limits of our book will prevent any further description of volcanic districts or regions, we must content ourselves with descriptions of some of the noted of the remaining volcanoes, although many we will thus omit contain great wonders. as we have already seen from the description of krakatoa, the island of java near which krakatoa is situated is especially noted not only for the great number of its volcanic mountains, but also for the frequency and severity of their eruptions. perhaps the most destructive eruption of any of the volcanic mountains of java was of a volcanic mountain called papandayang. this volcano, situated on the southern coast of the island, is , feet in height, and was in eruption in . according to scrope, from whom the details of this eruption have been obtained, two others of the many volcanoes on java, situated at and geographical miles respectively from papandayang, broke out at the same time into active eruption, although several intervening cones were undisturbed. the eruption of papandayang was of the explosive type, a large part of the mountain being broken off by the great force of the eruption, and its materials scattered far and wide over the surrounding country. during this eruption forty villages with their inhabitants were buried by great showers of ashes. an area of fifteen by six miles was left in the shape of a huge pit by the great eruption. it was at first believed by some that this pit was due to the actual sinking in of the ground, but a more careful study has shown that it was in reality caused by the great force of the eruption, being, in point of fact, a vast explosive crater that was formed by the expulsion of the materials that formerly filled it. some idea of the great extent of this eruption of papandayang may be had by the size of this huge crater that was six by fifteen miles in diameter. another great volcanic mountain in java that had a terrific eruption was galungoon, or galung gung. according to lyell, from whom the facts of this eruption have been obtained, prior to this eruption the slopes of the mountain were highly cultivated and densely populated. there was a circular pit or crater on the summit of the mountain, but there had been no traditions of any eruptions prior to . in july, , the waters of the kunir river, one of the small rivers that flow down the slopes of the mountain, were observed to become hot and turbid. on the th of october, , a terrific explosion was suddenly heard, accompanied by great earthquake shocks, when immense columns of hot water and boiling mud, mixed with burning brimstone, ashes, and lapilli, were thrown violently like a great waterspout from the opening in the mountain, with such enormous violence that great quantities fell across the river tandoi, forty miles distant, while the valleys in the neighborhood were filled with a burning torrent. the rivers overflowed their banks and produced great destruction by floods of burning and boiling materials that washed away all the villages and cultivated fields in their path. during this eruption an extended area was covered with boiling mud in which were completely buried the bodies of many of those who perished. so great was the violence with which the boiling mud, cinders, etc., were thrown out of the mountain that they entirely failed to fall on many of the villages in the immediate neighborhood, while the more remote villages were completely destroyed and buried out of sight under the mud. the first eruption continued for nearly five hours. during several days following the eruption, torrents of rain fell, which produced floods in the rivers that covered the country far and wide with thick layers of mud. four days after the great eruption, that is, on the th of october, , a second and still more violent eruption occurred, when immense quantities of hot mud were again thrown out of the crater. great blocks of hardened lava called basalt were thrown a distance of seven miles from the volcano. this eruption was accompanied by a violent earthquake. it was during this eruption that a huge piece of the side of the cone was blown out, not unlike the case of the val del bove on mt. etna. the surrounding country was covered with mud. the immense quantity of materials thus thrown out of the side of the mountain produced changes in the courses of several rivers, thus causing great floods which in the single night of october th drowned , people. during these eruptions there were villages destroyed, with a total loss of life of about , . there is a volcanic mountain on the island of sumbawa that is noted for the very destructive eruption that occurred on it in april, . if you examine the map of the sunda islands chain, you will see that the island of sumbawa lies immediately east of a little island called lombock, about miles east of java. this eruption of sumbawa was of the most frightful violence, and, indeed, with the exception of krakatoa and pelée, was one of the greatest eruptions in historic times. like all great eruptions, that of sumbawa gave plenty of signs of its coming. during april, , the volcano manifested considerable increase in its activity, and ashes fell on the decks of vessels sailing past the island. the eruption began on april th, , but reached its greatest violence on the th and th of april. according to lyell, the sound of the explosion was heard at the island of sumatra at a distance of geographical miles towards the west, and in the opposite direction it was heard for a distance of miles. the destruction of life was terrible. out of a population of , in the province of tomboro, only twenty-six people escaped with their lives. like many other great eruptions the shooting upwards of the great column of matter from the crater produced a violent whirlwind that carried people, horses, cattle, and almost every movable object high into the air, and tore up huge trees by their roots. immense quantities of ashes fell over the surrounding country, or were carried towards java to the west a distance of miles, while on the north they were carried towards celebes for a distance of miles. cinders covered the ocean towards the west two feet thick and several miles in length, so that ships could hardly make their way through them. the darkness in java produced by the dense ash cloud was greater than had ever before been experienced with the single exception of the great eruption of krakatoa. a considerable quantity of this volcanic dust was carried to the islands of amboyna and banda, the last named island being at a distance of miles east of the volcano. this eruption of sumbawa was attended by great lava streams that covered vast areas of the land and afterwards poured into the sea. as in the case of the explosive eruption of krakatoa great waves were produced in the ocean all along the coasts of sumbawa, and surrounding islands. the sea suddenly rose from two to twelve feet. a great wave rushed up the mouths of the rivers, and at the town of tomboro, on the west side of sumbawa, an area of land was sunk in the waters and remained permanently covered by eighteen feet of water. the most important of the still active volcanoes of japan is assamayna. this mountain was in terrible eruption during the autumn of , when dense showers of ashes thrown out of the crater darkened the sky, turning the day into night, and, falling on the cultivated fields around the mountain, changed them into deserts. during the eruption some forty-eight villages were destroyed by showers of ashes and red hot stones and thousands of the inhabitants were either killed directly by the stones and ashes, or died from starvation, since their fields were covered with ashes for miles around to a depth of from two and a half to five feet. another terrible eruption in japan was in the volcanic mountain of wunzen, or onzen-gatake. this occurred during - . during the last eruption of this volcano, , people lost their lives, either by reason of the eruption of the volcano, or by huge waves set up in the ocean by an earthquake. chapter xiii jorullo, a young volcanic mountain you must not suppose that when we speak of jorullo as a young volcanic mountain that we mean young in the sense that you or i might be called young, but young as regards mountains; for jorullo, now a great mountain range, had no existence before the year , and that would make the mountain a little less than years old, which so far as mountains are concerned may properly be regarded as quite young. the story of jorullo is very interesting, and affords an excellent example of the great scale on which modern volcanic eruptions take place during historical times. if you examine the map of mexico on page you will see that jorullo lies miles southwest of the city of mexico, and miles from the pacific ocean, which is the nearest large body of water. this mountain is of especial interest because, if old traditions are to be believed, it was thrown up during practically a single night. this wonderful event took place on an elevated plain or plateau, called the plain of malpais, that lies between , and , feet above the level of the ocean. the plain was situated in a part of mexico that was celebrated for the growth of the finest cotton and indigo in the world. it formed the large estate of a wealthy planter, señor pedro de jorullo, who lived at his ease as a wealthy planter is apt to do in tropical countries like mexico. jorullo's plantation was covered by an especially fertile soil, since it was formed by the deposits of volcanic ashes, dust, tufa, etc., produced, most probably, by neighboring volcanoes long before man appeared on the earth, for the plain of malpais was bounded by hills that were composed of volcanic materials. there had, however, been no signs of volcanic activity in the neighborhood. it had indeed been quiet, so far as volcanic eruptions were concerned, since the time of the discovery of america by columbus, until the middle of the last century. the fertile fields of the jorullo plantation were watered by two rivers, or as we would probably call them, brooks, the cuitamba and the san pedro. signs were not wanting of the coming calamity. during june, , subterranean sounds were heard of a low rumbling character, which every now and then increased until they resembled in intensity the sounds produced by the firing of large guns. these sounds were accompanied by earthquake shocks that greatly terrified the people and caused them to flee from their homes. nothing, however, occurred, so, becoming accustomed to the noises, the people returned to their houses. the noises and tremblings ceased for over two months, until, on the th of september, , they were again heard, and a terrible eruption began. a long fissure opened in the earth, extending generally from northeast to southwest. from this fissure flames burst out, fragments of burning rock and stone, together with large quantities of ashes were thrown to great heights in the air, and were followed by streams of molten rock. six volcanic cones were formed along the fissure. the highest of these cones is what now constitutes the volcanic mountain of jorullo, which then reached a height of at least , feet above the level of the plain. from its cone were thrown out great quantities of lava of the same type as that which escaped from the craters of many volcanic islands such as hawaii and iceland, namely, basaltic lavas. this eruption, which began on the th of september, , continued until the month of february, . the account as above given was obtained by humboldt, who visited the country some fifty-six years after the eruption. this story was told him by the indians, but was also recorded in verse by a jesuit priest, raphael landiva, a native of guatemala. according to the account given humboldt by the indians, it appears that when a long time after the eruptions had quieted down, they had returned to their old homes with the hope of cultivating part of the grounds, they found the plains still too hot to permit their living on them. according to lyell, there was around the base of the cone, spreading from them as a centre over an area of some four square miles, a convex mass, about feet in height, most of the surface of which was covered with thousands of small flattish conical mounds from six to nine feet in height. these, together with numerous large fissures that crossed the plain in different directions, served as points for the escape of sulphur vapors, as well as for the vapors of hot water. during the escape of lava from the craters in , the molten rock, spreading over the plain, ran into the channels of the river or brooks before named, driving out the water. this water reappeared at the base of the mountain in numerous hot springs. humboldt thought that the conical mountains had been lifted or raised by the formation of huge bubbles formed under the lava, thus causing it to assume a shape not unlike that of a huge bladder. this opinion, however, has not been accepted by geologists at the present time. scrope points out that this was probably the origin of the little conical mounds that covered the surface of the principal conical mounds but was not, in all probability, the cause of the mound itself. he says: "with regard to the disputed question as to the origin of the raised plain of the malpais, m. de saussure, the last and most trustworthy visitor, entirely confirms the opinion which i ventured to proclaim in , that humboldt was mistaken in supposing it to have been 'blown up from beneath like a bladder,' and that it is merely an ordinary current of lava, which, owing to its very imperfect liquidity at the time of its issue from the volcanic vent, as well as to the overflow of one sheet or stream upon another, had acquired great thickness about its source, gradually thinning off towards the outer limit of the elliptical area it covered." if you have been able to follow the above you will see that mr. scrope means that in his opinion the cone of jorullo is a lava cone like that we have already studied on mt. loa or mt. kilauea, or, in other words, that the lava as it came out from the opening on the top of jorullo, flowed in all directions around the opening, thus building up a mountain in the form of a flat lava cone. perhaps one of the reasons humboldt had for believing the entire elevation of jorullo to be due to the formation of a huge bladder was the fact that the plain on which the cone is situated, when struck, gave out a sound as though there was a vast hollow space below it. this was especially the case when the hoofs of the horses driven over its surface produced sounds as though they were moving over the summit of a hollow dome-like space below. but, as lyell points out, this was probably only due to the fact that the materials forming the cone were very light and porous. according to burkhardt, a german mining engineer who visited jorullo in , there appears to have been no other eruptions of the volcano since the time of humboldt's visit. mr. burkhardt descended to the bottom of the crater and observed that small quantities of sulphurous vapors were still escaping. the small cones or _hornitos_, however, on the slopes had entirely ceased emitting steam. it appeared, too, that the twenty-four years that had passed since the time of humboldt's visit, the rich soil of the surrounding country had permitted the successful cultivation of some crops of sugar cane and indigo. russell appears to doubt the reliability of the information obtained by humboldt concerning jorullo. he suggests that a poetical account by the jesuit missionary from whom humboldt obtained much of his information was not apt to possess marked scientific accuracy. while, however, this may be true, yet to a certain extent it seems entirely probable that the principal facts were as above given. the following account as given by humboldt, is taken from a translation made in the early part of : "the affrighted inhabitants fled to the mountains of aguasarco. a tract of ground from three to four square miles in extent, which goes by the name of malpays, rose up in the shape of a bladder. the bounds of this convulsion are still distinguishable in the fractural strata. the malpays, near its edge, is only twelve metres above the old level of the plain called the playas de jorullo; but the convexity of the ground thus thrown up increases progressively towards the centre, to an elevation of metres ( . ft.). "those who witnessed this catastrophe from the top of aguasarco assert that flames were seen to issue forth for an extent of more than half a square league, that fragments of burning rocks were thrown up to prodigious heights, and that through a thick cloud of ashes, illuminated by the volcanic fire, the softened surface of the earth was seen to swell up like an agitated sea. the rivers of cuitamba and san pedro precipitated themselves into the burning chasms. the decomposition of the water contributed to invigorate the flames, which were distinguishable at the city of pascuaro, though situated on very extensive table-land , metres ( , ft.) elevated above the plains of las playas de jorullo. eruptions of mud, and especially of strata of clay enveloping balls of decomposed basalt in concentrical layers, appeared to indicate that subterranean water had no small share in producing this extraordinary revolution. thousands of small cones, from two to three metres in height, called by the indigenes ovens, issued forth from the malpays.... "in the midst of the ovens, six large masses, elevated from to metres each above the old level of the plain, sprung up from a chasm, of which the direction is from n. n. e. to the s. s. e. this is the phenomenon of the montenovo of naples, several times repeated in a range of volcanic hills. the most elevated of these enormous masses, which bears some resemblance to the puys de l'auvergne, is the great volcan de jorullo. it is continually burning, and has thrown up from the north side an immense quantity of scorified and basaltic lavas containing fragments of primitive rocks. these great eruptions of the central volcano continued till the month of february, . in the following years they became gradually less frequent.... the roofs of the houses of queretaro were then covered with ashes at a distance of more than forty-eight leagues in a straight line from the scene of the explosion. although the subterranean fire now appears far from violent, and the malpays and the great volcano begin to be covered with vegetation, we nevertheless found the ambient air heated to such a degree by the action of the small ovens, that the thermometer at a great distance from the surface and in the shade rose as high as ° c." ( ° ' f.). chapter xiv mid-ocean volcanic islands besides the volcanoes we have already described, there are many others situated in mid-ocean far from any continent. a brief description will be given of a few of these. all the three great central oceans, the pacific, the atlantic, and the indian, contain numerous volcanic islands, some of which rise many thousands of feet above the general level. we will begin with a description of some of the more important volcanic islands of the pacific. it was first pointed out by kotzebue, and afterwards by darwin, that all the islands of the pacific ocean can be divided into two great classes, the _high islands_ and the _low islands_. all the high islands are of volcanic origin, while the low islands are of coral formation. it is the opinion of dana, who has made a careful study of coral formations, especially in the pacific, that in all probability even the low islands of the pacific were originally volcanic, and that the deposits of coral had been made along their shores after their volcanoes had become extinct. the islands of the pacific, like the shores of the continents and most of their mountain ranges, extend in two great lines of trend, or general direction, which intersect each other nearly at right angles. these lines extend from the southeast to the northwest, and from the northeast to the southwest respectively, those extending in a general direction from southeast to northwest being the most common in the pacific. now, perhaps, the greatest number of the earth's volcanoes are arranged along fissures, or cracks in the earth's crust. the craters are situated along the cracks, the openings being kept clear at the crater, and gradually closing elsewhere, probably by pressure. in other words, most of the volcanoes follow one another along more or less straight lines. for example, in the western part of south america they follow the andes mountains. a similar arrangement exists in the volcanoes of central america, mexico, and the united states. now, this is especially true of mid-ocean volcanoes of the pacific which lie along lines extending from southeast to northwest, or from northeast to southwest, though mainly along the former. some of the volcanic islands of the pacific have already been described or referred to, as, for example, the aleutian islands, which stretch in a curved line from the southwestern extremity of the peninsula of alaska to kamtschatka on the coast of asia. we have already described the island of hawaii, the great volcanoes of the sandwich islands chain, and besides these there are in the north pacific the ladrone islands, lying east of the philippines. some of the principal remaining islands are: the fejee islands, which are volcanic, with numerous hot springs and craters. the friendly islands, with the peak of tafua, , feet high, an active volcano with a large crater always burning, and two other volcanoes, apia, and upala. tahiti, to the east, is at present extinct. one of its mountains, orobena, said to be , feet high, has a crater on its summit. the marquesas, still further to the east, are also volcanic. all of these islands lie generally in the lines of the northeast trend. the tongan or new zealand island chain extends in the direction of the northeast trend. this, as you will see, is the direction in which the two islands of new zealand extend. the tongan island chain is continued to the south through auckland and the macquaire islands to ° s. towards the north, in almost the same line, are the kermadec islands near ° s. there are several active volcanoes in new zealand. an explosive eruption of tarawera, in new zealand, in , continued for several days, and was followed, three days afterwards, by an outburst in an active volcano in the bay of plenty, and two months afterwards, by a violent outburst in a volcano on the island of ninafou in the tongan islands. coming now to the atlantic ocean we find a number of volcanic mountains in the deep waters near mid-ocean. the principal of these, besides iceland, are the azores, the canaries, cape verde islands, ascension island, st. helena island, and tristan d'acunha. the peak of pico, in the azores, rises to a height of , feet. the peak of teneriffe, in the canaries, reaches the height of , feet. teneriffe is a snow-capped mountain. it has a cone on its summit with precipitous walls like vesuvius. sulphurous vapors are continually formed at its summit, but no flames can be seen. in the cape verde islands is to be found the active volcanic mountain of fuego, rising , feet above the sea. it has a central cone that has been broken down on one side like that of somma on vesuvius. fuego was in eruption in , and also in . ascension island, south of the equator, is formed entirely of volcanic materials. this island rises from an apparently granite floor on the bed of the ocean, in water , feet deep. st. helena lies further to the south. it is an extinct volcano, and has the remains of a crater on its summit with lava dikes in various parts of the island. tristan d'acunha is an isolated mountain that lies in the south atlantic, south of st. helena, , miles from africa, the nearest land. it is an extinct volcano that rises from a depth of , feet to a height of , feet above the sea. it has a truncated cone on its summit and a lake of pure water in its old crater. there are only a few volcanic islands in the indian ocean. kerguelen island lies in the southern waters. st. paul and amsterdam to the north, lying near ° s. lat., as well as the crozet islands, are extinct volcanoes. in the arctic ocean is the volcanic island of jan mayen. in the antarctic ocean, as far as is known, there are only two volcanoes, mt. erebus and mt. terror. mt. erebus, , feet high, is an active volcano. mt. terror, , feet high, is an extinct volcano. chapter xv submarine volcanoes a submarine volcano is a volcano that erupts on the bed of the ocean with its crater covered by the waters. many of the great volcanic mountains of the world began as submarine volcanoes. a crater first opened on the floor of the ocean, and lava escaping, was heaped up around the opening, until it emerged above the surface as an island. as we have seen, the island of iceland is believed to have begun in this way. such, too, in all probability, was the origin of hawaii, vesuvius, etna, and santorin. but besides the volcanic mountains that were thrown up during the geological past, there are others that have been called into existence while man has been living on the earth. we will now describe a few islands that have been formed in this manner by submarine volcanic eruptions. that volcanic eruptions, or at least something that greatly resembles eruptions, occur on the bed of the ocean too far below the surface to permit them to be directly seen from above, has been shown in a number of cases where the captains of vessels have reported that in certain parts of the ocean, jets of water, or steam, and pillars of flame have been seen rising to great heights from the surface of the water, and that in certain regions sulphurous smoke has also been seen. during such occurrences, the water is agitated, as if it were being violently boiled. moreover, these parts of the ocean are shaken by severe earthquake shocks. another evidence of submarine volcanic eruptions is to be found in great quantities of ashes, scoriæ, or pumice stone, that are seen spread out over the surface of the ocean after the commotions referred to in the preceding paragraph. still another proof is that parts of the ocean whose waters were previously very deep are found to have suddenly shoaled. of course, the best proof is the appearance of rocky reefs or small islands thrown up above the surface of the water, especially where volcanic cones appear. while in many cases the new islands thus thrown up are subsequently washed away by the waves, yet some have continued above the water. one of the most noted instances of the formation of an island by a submarine volcano was sabrina, which was thrown up in , in the atlantic ocean, off the shores of st. michael in the azores islands. sabrina had a cone that was feet in height. it did not long remain above the waters, however, being soon washed away by the waves. it is interesting to note that in the same part of the ocean where sabrina appeared, other islands have appeared and disappeared, at times long before ; that is, during the year , as well as during . another instance of a submarine island is graham's island, that was thrown up in , in the mediterranean sea, between the west coast of sicily and the nearest part of africa, on which ancient carthage was situated. the part of the sea where the island was thrown up had previously a depth of feet. the general appearance of graham's island is represented in fig. . graham's island was formed by accumulations of loose scoria and cinders, together with blocks of lava and fragments of limestone. it reached a height of feet above the water, but only remained above the surface for a few months, when it was washed away, leaving a submarine bank some twelve miles in width, that was covered by water of about feet, but which, however, increased rapidly in depth towards the edge until depths of from , to , feet were reached. [illustration: fig. . graham's island--a recent volcanic island] according to lyell, on the th of june, , before graham's island appeared, a ship passing over this portion of the sea felt severe earthquake shocks. on july th of the same year, the captain of a vessel from sicily reported that as he passed near this part of the mediterranean, a column of water, yards in circumference, was seen to rise from the sea to a height of sixty feet, and that afterwards a column of steam rising to a height of , feet was seen in the same place. on again passing the same region on july th, this captain found a small island about twelve feet in height, with a crater in its centre, that was throwing out volcanic materials, together with immense masses of vapor. the island thus formed grew rapidly, both in size and height. when visited at the end of july, it had attained a height of from fifty to ninety feet, and was three-quarters of a mile in circumference. by august th, it had reached a height of feet, and was then some three miles in circumference. from this time, however, the island began to decrease in size, as the waves began to wash it away. by august th, it was only two miles in circumference. on september d, it had decreased to three-fifths of a mile in circumference, and continued to decrease until it entirely disappeared, so that in the year , there were, according to measurements, some feet of water over its former site. the mediterranean sea between sicily and greece is also especially liable to submarine activity. new islands appear and disappear so frequently that in this region they are almost regarded as common phenomena. there are many other parts of the ocean where submarine volcanic eruptions are common. this is especially the case in the narrowest part of the atlantic ocean between africa and south america. here there is a region situated partly above the equator, though for the greater part south of the equator, frequently visited by submarine eruptions, that are accompanied by earthquakes, by the agitation of the water, by the appearance of floating masses of ashes and scoriæ, as well as by columns of steam or smoke. floating masses of ashes and scoriæ sometimes occur so thick as to retard the progress of vessels. but what forms, perhaps, one of the best instances of a large island formed by submarine eruptions during historical times, is bogosloff island in behring sea, some forty miles west of unalaska island. this island, the position of which is seen on the accompanying map, is known to the russians as ioanna bogoslova, or st. john the theologian. it is situated in lat. ° ' n., long. ° west. it is said that during the year , some of the natives of unalaska island saw what they thought was a fog in the neighborhood of a small rock, which they had known for a long time to project above the sea in these waters. this rock was marked on some russian chart dated - . it was seen by captain cooke, in , and was named by him ship rock. but it was not a fog that the unalaskans had seen in the neighborhood of ship rock; for, to their great surprise, the fog continued in sight although everywhere else the air was quite clear. of course, this was a great mystery to the people. during the spring of , one of them, who possessed either greater curiosity than the rest, or greater courage, or both, visited the rock. he returned, telling the strange story that all the ocean around the rock was boiling, and that the mist or fog was caused by the rising steam. what was taking place was a submarine eruption. during may, , sufficient matter had been brought up from below to increase greatly the area of the small rock. [illustration: fig. . aleutian islands] during later years several attempts have been made to visit bogosloff island. for example, the island was visited during and , when it was found to have increased in height to feet. but no appearance of any volcanic crater was to be seen. during october, , a great volcanic eruption occurred there. considerable changes were produced in its shape, as well as in the depth of the surrounding water. during this eruption, clouds of steam completely hid the island. great quantities of ashes obscured the light of the sun. after the eruption, a new island was thrown up near the old one, in a place where the water had previously been deep enough for the ready passage of ships. the new island was about half a mile from the old one. it was conical in form, from to feet in height, and about three-quarters of a mile in diameter. the new island was visited in by the u. s. revenue marine steamer _corwin_. lieutenant cartwell, who visited the island at this time, described it as follows: "the sides of new bogosloff rise with a gentle slope to the crater. the ascent at first appears easy, but a thin layer of ashes, formed into a crust by the action of rain and moisture, is not strong enough to sustain a man's weight. at every step my feet crushed through the outer covering and i sank at first ankle-deep and later on knee-deep into a soft, almost impalpable dust which arose in clouds and nearly suffocated me. as the summit was reached, the heat of the ashes become almost unbearable, and i was forced to continue the ascent by picking my way over rocks whose surfaces being exposed to the air, were somewhat cooled and afforded a more secure foothold. "on all sides of the cone there are openings through which steam escaped with more or less energy. i observed from some vents the steam was emitted at regular intervals, while from others it issued with no perceptible intermission. around each vent there was a thick deposit of sulphur, which gave off suffocating vapors." chapter xvi distribution of the earth's volcanoes having now considered at some length the principal volcanoes of the earth, and endeavored to obtain some idea of the many wonders they exhibit, especially as regards the vast quantities of material they bring from the inside of the earth, as well as the great force with which they sometimes throw these materials out of their craters, it will be well to point out where such volcanoes are to be found. it may have seemed to you, when you have carefully followed what has been said about the earth's volcanoes, that they are to be found pretty nearly everywhere, at least so far as latitude is concerned; and in this supposition you are correct; for there are volcanoes in the arctic ocean, as in the volcanic island of jan mayen between iceland and spitzbergen, there are mt. erebus and mt. terror in the antarctic ocean, besides very numerous volcanoes in the atlantic, pacific, and indian oceans, and their shores in both the temperate and the torrid zones. there is, however, one thing that you have probably especially noticed and that is that volcanoes are seldom found at very great distances from the ocean, except on some of its arms or seas, such as the mediterranean sea. i do not mean by this that all the earth's volcanoes are either situated directly on the coast of the continents or on islands, since, in such a large body as the earth, a distance of a few hundred miles from the ocean is hardly to be regarded as being very far from it. but it is true that all the earth's volcanoes are either situated on the coasts of the continents, or on islands, and, moreover, they are situated to a greater or less extent along lines, which, as we have already pointed out, are believed to mark weak portions of the earth's crust that have been fissured or fractured. in order that you may have some idea of this distribution, i think it will be well to give you a number of interesting facts that have been pointed out by dana. according to this authority, there are something in the neighborhood of active volcanoes on the earth. of these, no less than five-sixths, or , lie either on the borders of the pacific ocean, or on some of its many islands. thirty-nine either lie within or on the borders of the atlantic, of which thirteen are in iceland, or near the arctic circle, three in the canaries, seven in the mediterranean sea, six in the lesser antilles, and ten in the atlantic oceanic islands. the indian ocean contains only a few active volcanoes. there are, however, a much greater number of extinct volcanoes, which may at any time again become active. the following is the distribution of the earth's volcanoes as given by dana. as you will see, from an inspection of fig. , all of the regions of volcanoes lie either on the borders of the continents, or on islands in the oceans. the districts are as follows: . _scattered over the pacific ocean._--this district includes the following active volcanoes; i. e., the hawaiian islands, nearly in mid-ocean, almost directly below the tropic of cancer; in the west central parts of the south pacific; in the new hebrides; in the friendly islands, the tongan or new zealand islands, in the santa cruz islands, and in the ladrones. [illustration: fig. . map of the world, showing location of active and recently extinct volcanoes] . _on the borders of the pacific._--this district includes the volcanoes that extend from the southern part of south america at intervals along the andes mountain range. of these there are thirty-two in chile, seven or eight in bolivia and southern peru; about twenty in the neighborhood of quito. further north there are thirty-nine in central america, and seven in mexico. proceeding northwards through the united states, there are a number of volcanic mountains, generally extinct, in portions of the sierra nevadas and cascade ranges. probably a number of volcanic mountains exist in portions of canada lying between the northern boundaries of the united states and alaska, and a number in alaska; some twenty-one volcanic mountains in the aleutian islands; some fifteen or twenty in kamtschatka; thirteen in the kuriles; some twenty-five or thirty in japan and the neighboring islands; some fifteen or twenty in the philippines; several along the northern coasts of new guinea; a number in new zealand and south of cape horn; the volcanoes of the deception island with its hot springs, and also in the south shetlands ° ' s. . _in the indian ocean._--on the western border of the indian ocean there are a few volcanoes in madagascar; in the island of bourbon; mauritius; the comoro islands; and in kerguelen land on the south. there are also volcanoes on the western border of the indian ocean where the lofty peak of kilima ndjro, , feet, is volcanic. . _over the seas that separate the northern and the southern continents and in their vicinity._--this is an especially active region of volcanoes. for the sake of convenience the continents of the world are sometimes divided into three pairs or double continents; namely, north and south america, connected by the isthmus of panama; europe and africa, connected by the isthmus of suez; and australia and asia, completely separated by a sunken isthmus, the summits of which form the sunda island chain. in the first of these regions we have the very active group of the west indies, where there are ten volcanic islands. in the second pair of double continents we have the volcanoes of the mediterranean and red seas, and their borders, such as sicily, vesuvius, and other parts of italy, spain, germany, the grecian archipelago, asia minor, and extending eastward through the caspian, mt. ararat, demavend, on the south shores of the caspian, mt. ararat, and some few others along the borders of the red sea. in the east indies we find the most intense centre of volcanic activity in the world. here there are some volcanoes of which there are nearly fifty in java alone, more than half of which are still active. there are nearly as many volcanoes in sumatra, and many in the small islands near borneo, the philippines, etc. . _on the borders of the atlantic and elsewhere._--it is an interesting fact that there are no volcanoes on the eastern borders of the atlantic north of the west indies island chain. in the south atlantic the only volcano on the borders is one of the cameroons mountains. in the atlantic ocean we have iceland, the azores, the canaries, cape verde, ascension, st. helena, and tristan d'acunha. this curious distribution of the volcanoes of the world near the oceanic waters appears to be dependent rather on the very early shapes of the continents and the ocean beds than on their present shapes. chapter xvii volcanoes of the geological past the question is often asked whether the volcanic eruptions of the geological past were not much more violent and destructive than the volcanoes of the present time. now, while this is a matter that properly belongs to the subject of geology, and will be treated at greater length in the wonder book on geology, yet a short mention should be made of it here. it is the opinion of dana that while there have been volcanoes during the different geological ages, yet volcanic activity has increased through the geological past until the age that immediately preceded the appearance of man on the earth. he thinks there is no reason for believing that there were any very great volcanic eruptions during the earliest geological time known as the archæic. dana speaks as follows concerning this: "in this connection it is an instructive fact that in eastern north america, at epochs when there was the greatest amount of friction and crushing ... those of the making of the green mountains and the appalachians ... no volcanoes were made, and little took place in the way of eruptions through fissures." on the other hand, prestwich seems inclined to think that the absence of well-marked cones of volcanic material in the rock of the older geological ages is not to be regarded as proof that no eruptions then took place, since the very great amount of erosion that occurred between that time and the tertiary age before the appearance of man, would, probably, have completely obliterated any cones, and even the volcanic materials would have undergone such changes as completely to alter their general character. he agrees, however, with dana that, probably, the most violent and explosive volcanoes of the geological ages have been those of the tertiary age. without, however, attempting anything more than a brief reference to the volcanoes of the geological past, it may be said that many of the more important of the active volcanoes of the earth's present time were begun in the tertiary age. mt. etna, vesuvius, and mt. hecla are believed to have commenced at this time. there is an interesting region of geological volcanoes in the neighborhood of auvergne in central france. here they occur in three separate groups that extend over a high granite platform from north to south for a distance of about miles, and from twenty to eighty miles from east to west. the eruptions began in the earlier portions of the tertiary age, and continued down to the latter periods of prehistoric times. some of these volcanic craters remain to-day almost as unaffected by erosion as if they had been formed but recently. other regions of geological volcanoes are to be found in parts of spain near the foot of the pyrenees mountains, in parts of italy and germany, as well as in regions in the caucasus mountains. in asia minor there exists a group of almost thirty extinct volcanoes in the neighborhood of the gulf of smyrna. both little and great ararat contain volcanic cones: that in the latter mountain was active during historical times. there are also extensive volcanic districts in the taurus mountains. in addition to these there are groups of extinct volcanoes in portions of central asia. aden, on the red sea, is the centre of an extensive volcanic district. indeed, on both shores of the red sea there are a few volcanoes that are still active, while in sinai, and in the districts of the south, there are several extinct craters. but it is in the new world, especially on the pacific coast of north america, that volcanic activity was especially great during the geological past. there is a district containing volcanic rocks that extends through various parts of western north america, from new mexico and north california, to oregon and british columbia. this district has a width of from eighty to miles, and a length of not quite miles. this great area of nearly , square miles is covered with great sheets of volcanic rocks except where mountain ranges rise from them, or where the rivers have cut deep valleys through them. in portions of california and new mexico these plateaus rise to heights of from , to , feet, while in parts of colorado, where they form huge dome-like mountains, they reach a thickness of , feet. in oregon the sheet of lava is , feet thick, and, indeed, in some places, is estimated to have a depth of , feet. in the opinion of nearly all american geologists these great lava flows in western north america were not of the type known as crater eruptions, but were what are called fissure eruptions. some of them are believed to have occurred during geological times as early as the eocene. prestwich, however, is of the opinion that the eruptions of the past in these portions of the world were not confined to fissure eruptions, but that crater eruptions also occurred; and that it was towards the close of the tertiary age that crater eruptions occurred with great lava flows. indeed, as we have seen, in portions of utah and the neighborhood the remains of true craters can be found. besides the above there are evidences of geological volcanoes of still older times. in portions of deccan, in southern hindostan, there is an immense plateau formed of trap rock, that extends from east to west for a distance of miles, and from north to south through from to miles. this district, with an area of almost , square miles, is covered with a vast lava sheet. it was, in the opinion of prestwich, from whom many of the facts of the geological volcanic eruptions have been obtained, probably still more extensive. the plateau of deccan rises gradually from the east to the west, where, in some parts of the ghauts mountains, it reaches a height of from , to , feet. one of the greatest of these prehistoric volcanoes of scotland was a volcano in the isle of mull in the hebrides. this volcano was probably nearly thirty miles across at its base, and was from , to , feet high. it is now only , feet in height. according to judd the island of skye in inverness-shire is the remains of a volcano that was active in tertiary times, probably many millions of years ago. this volcano was very large, probably about thirty miles across at its base, with a height of perhaps as great as , or , feet. now there are only left some granite and other similar rocks that form the red mountains and coolim hills of skye that reach about , feet above the sea level. there are many other parts of the world containing volcanoes that were active during the geological past. the above, however, is as far as we can describe such volcanoes in this book. chapter xviii laplace's nebular hypothesis laplace's nebular hypothesis is the name given to an ingenious hypothesis proposed by laplace, a celebrated french astronomer, in an endeavor to explain how the solar system has been evolved. you will notice that this is called a hypothesis and not a theory. the word hypothesis is properly applied to a more or less intelligent guess or assumption, that has been made for the purpose of trying to find out in the cause of any natural phenomenon. a theory is an expression of a physical truth based on natural laws and principles that have been independently established. a theory, therefore, is much more complete than a hypothesis. a hypothesis, as silliman remarks, bears the same relation to a theory or law, that a scaffolding does to a completed building, since it forms a convenient means for erecting the building. laplace's work is properly called a hypothesis, because it is not to be considered as any more than a means for enabling one intelligently to inquire into the probable manner in which the solar system has reached its present condition, by gradual steps or stages during the almost inconceivable length of time since its creation. before describing laplace's hypothesis it will be necessary to give you some ideas concerning what is known by astronomers as the solar system. the solar system consists of the sun, and the eight large bodies called planets that revolve around the sun. it also includes a number of moons or satellites revolving around the planets, a number of small bodies, called planetoids or asteroids, together with numerous comets and meteorites. besides these there is probably a system of meteoric bodies that are believed to revolve around the sun, and to produce, by the reflection of the light from their surfaces, what is known as the _zodiacal light_. the principal bodies of the solar system are the planets. these constitute eight large bodies named in their order from the sun, beginning with the nearest: mercury, venus, earth, mars, jupiter, saturn, uranus, and neptune. the last four planets, jupiter, saturn, uranus, and neptune are much larger than the others, and are therefore known as the _major planets_ in order to distinguish them from mercury, venus, earth, and mars, which are called the _minor planets_. you can remember the order in which the last three planets come by their initial letter, s-aturn, u-ranus, and n-eptune, spelling the word sun, around which they all revolve. it may be interesting to state here that the ancients knew of seven only of these planets. since, as they asserted, there were only seven days in the week, and seven openings into the head; i. e., two for the eyes, two for the nostrils, two for the ears, and one for the mouth, it was natural that there should be but seven planets. during later years, however, an eighth planet was discovered and named neptune. it would be interesting to explain to you how the position of this planet was reasoned out by mathematical calculations, that is, in other words, how, as a result of such calculations, an astronomer was told that if he would point his telescope to a certain part of the heavens he would discover a new planet. he did this and located the planet neptune. however interesting this story may be it belongs properly to astronomy, and will be described in full in the wonder book of astronomy. in the opinion of some astronomers it is quite probable that a ninth planet will be found far beyond the orbit of neptune. there may also be some additional planets discovered between mercury and the sun. besides the eight known planets there exist, somewhere between the orbits of mars and jupiter, many smaller planets called _asteroids_, or _minor planets_. a long time ago it was pointed out by bode that a curious relation exists between the distances of the planets from the sun. this relation or law is generally known, after the name of the astronomer who first called attention to it, as _bode's law_. no reason has been discovered for this arrangement of the planets, so that bode's law may be regarded as empirical. it may, however, be mentioned here that the distances of all the planets from the sun agrees with the law very closely, with the single exception of neptune, which is quite at variance with the law. it was noticed at an early date, that a gap existed between mars and jupiter, so that astronomers began to believe that there was probably a missing planet in that space, and this belief was greatly strengthened when neptune was discovered in . without going any further into this story in this book, it may be said that it is the general opinion of astronomers that the planetoids or asteroids were formed possibly from the fragments of the missing planet, or, more probably, from the breaking up of some of the outer rings on the planet mars. the distances of the planets from the central sun vary from the nearest planet, mercury, which is about , , miles from the sun, to the furthest, or neptune, which is , , , miles from the sun. all the major planets have a single moon, or more, revolving around them. for example, jupiter has four moons; uranus, six; saturn, eight; neptune, one. as to the minor planets, mars has two moons; and, as far as is known, neither mercury or venus has a moon. our earth has one moon, but, as we shall afterwards see, this is not to be regarded as a moon or satellite of the earth, but rather as a twin planet to the earth. laplace's nebular hypothesis was proposed by laplace during the year . while there are many objections that can be brought against it, since it fails to account for all of the phenomena of the solar system, yet it is a significant fact now, in the year , nearly a century and a quarter after the hypothesis was first announced, that although modified in many respects, there has not been any hypothesis proposed to entirely replace it. while the nebular hypothesis of laplace is necessarily a matter that belongs to astronomy, yet it will be advisable to consider it here, since it explains the source of the original heat of both the earth and the moon, which we believe is the true cause of volcanoes. in his nebular hypothesis, laplace assumes that all the materials of which the solar system is formed, were originally scattered throughout space in the shape of an exceedingly rare form of matter known as nebulous matter. he points out that if it be granted that this medium began to accumulate around a common centre, so as to form a huge globe or sphere, and if a motion of rotation on its axis from west to east were given to this sphere that, on strictly mechanical principles, a system of heavenly bodies corresponding to the solar system might have been evolved. let us, therefore, try to understand how this might have been brought about. the nebulous matter that laplace assumed originally constituted all the matter in the solar system, was highly heated gaseous matter. in other words, it consisted of ordinary matter raised to a very high temperature; laplace thought at a temperature very much hotter than that of the sun. as this great mass of matter commenced to cool, it began to collect around a centre and slowly rotate. its contraction or shrinkage, while cooling, must have caused an increase in the speed with which it spun around or rotated on its axis. at first it spun but sluggishly, but as it cooled and began to shrink this rate of rotation began slowly to increase. now you must bear in mind that the huge rotating mass, as imagined by laplace, was very many times larger than the size of our present sun. indeed, instead of having a diameter of only , miles, its temperature was so high that the nebulous matter of which it was composed had expanded it so much that it extended far beyond the orbit of neptune, or had a diameter twice as great as , , , miles. as the huge mass continued to shrink or contract, its rotation began to gradually increase until at last its centrifugal force was sufficiently great to cause it to bulge out at the equator, so as at last to separate a ring of gaseous matter. this ring was left behind by the sun, as it continued cooling, and formed the first planet that was born into the solar system. the ring might have continued to revolve around the sun for a time, and would, of course, revolve in the same direction as that in which the sun was rotating, that is, from west to east. eventually, however, it broke up into smaller fragments, that afterwards collected in a single body, and, assuming a globe-like shape of the planet, formed the planet neptune. necessarily, too, the planet so formed not only would revolve in its orbit from west to east in the same direction in which the sun was revolving on its axis, but would also rotate or spin on its axis in the same direction. after, in this way, throwing off the first planet, the central sun continued to cool and grow smaller, until the increase in the rate of its rotation was again such as to permit its centrifugal force to form a second ring around its equator, which being left as the sun continued to contract, gave rise to another planet, or to uranus, and so on until the four major planets and the four minor planets were born. according to this hypothesis, the planet that was first born was the planet that is farthest from the sun, that is, neptune, and the planet last born must have been the nearest planet, mercury. but while all this planet forming was going on, the separate planets also continued to shrink, and, therefore, began to rotate more rapidly on their axes. under the influence of the centrifugal force, ring-like masses began to form around their equators, and these masses left by the planet constituted their moons or satellites. as you can see, according to this hypothesis, just as the planets would all revolve in their orbits from west to east, and rotate on their axes in the same direction as the sun, so, too, the moons or satellites of the planets would also rotate on their axes, from east to west, and revolve in their orbits in the same direction. in order to show the extent to which laplace's nebular hypothesis explains the peculiarities of the solar system, we must inquire what are the most important of these peculiarities. we will take these from young's general book on astronomy, from which most of the facts in this chapter have been condensed. they are as follows: the orbits of nearly all the planets and their satellites are nearly circular; they are all in the same plane; and all revolve in the same direction. they are, moreover, with the single exception of neptune, arranged at distances from the sun in accordance with bode's law. all the planets increase in both directions, towards and from the sun, in density from saturn, the least dense. all the planets, with the exception probably of uranus, rotate in a plane that is nearly the same as the plane of the orbit in which they revolve. moreover, with the exception of probably both uranus and neptune, all the planets rotate in the same direction as that in which they revolve. the satellites revolve in orbits whose planes nearly coincide with the plane of the planets' rotation, while the direction of the revolution of the satellites is the same as that in which their planets revolve. finally, the largest planets rotate most swiftly. now, laplace's nebular hypothesis explains nearly all of the above facts. the following modifications of the hypothesis, however, are necessary. let us briefly examine some of these modifications. in the first place it can be shown that the original nebulous mass instead of being at a higher temperature than that of the sun was probably at a much lower temperature, since the condensation of the gaseous matter must have increased the temperature. instead, therefore, of the original nebulous mass being purely gaseous it was, as young expressed it: "rather a cloud of ice cold meteoric dust than an incandescent gas or a fire mist." or in other words, the original nebulous mass from which the solar system was evolved, consisted of finely divided particles of solid or liquid matter surrounded by an envelope of permanent gaseous matter. a doubt, too, has been raised as regards the manner in which the planets were liberated from the central sun. instead of separating in the form of a regular ring, it has been thought that probably in most cases this separation assumed the shape of a lump. it might, however, have occurred at times in the ring-like form as may be seen in the case of the planet saturn. again, instead of the outer rings being separated first, and the others in regular order, so that the outer planets are much the older, it would seem possible, or, as young states, even probable, that several of the planets may be of the same or nearly the same age, as they would be if more than one ring had been separated at one time, or, indeed, several planets may have been formed from different zones of a single ring. as you will see, laplace's nebular hypothesis assumes that both sun and moon were in a highly heated condition when they were separated from the nebulous sun, so that we can understand that the former molten condition of their interiors was due to the heat they originally possessed. chapter xix the earth's heated interior, the cause of volcanoes as we have already seen, the nebular hypothesis of laplace would seem to make it more than probable that the earth was originally in a highly heated condition, and only reached its present state after long cooling. while this cooling has gone on for probably millions upon millions of years both before and during the geological past, yet in the opinion of perhaps the best geologists the interior of the earth is still very hot, only the outer portions or crust having hardened by loss of heat. that there is a very hot region somewhere inside the earth is evident, since from some place or places below the surface there come out the immense streams of lava that, continuing to flow at irregular intervals, have at last built up such great masses of land as the island of hawaii, the still greater island of iceland, the even greater lava fields of the western united states, and the great plateau of the deccan in southern hindustan. it certainly must have required a great quantity of lava to build up an island like hawaii with its area of fully , square miles, for the highest point on the summit of mt. kea reaches , feet above the level of the sea, and, moreover, stands on the bed of the pacific ocean in water fully , feet deep. but iceland is only one of many similar cases. volcanoes are to be found in practically all parts of the earth, not only in the equatorial regions, where they are especially numerous, but also in the frigid and temperate zones. we must also remember the immense lava streams that are known to have come from the interior during the great fissure eruptions of the geological past. when all these facts are taken into consideration, it would certainly seem that there is only one source sufficiently great to supply this wonderful demand, and that is the entire inside of the earth. but entirely apart from volcanic phenomena there are other proofs that the entire interior of the earth is in a highly heated condition. the differences of temperature caused by the sun during day and night do not affect the earth much below a depth of three feet, while the differences of temperature between summer and winter do not extend much further below the surface than forty feet. below these depths, in all parts of the earth, the temperature of the crust rises at a rate, which, although not uniform, yet is not far from an increase of one degree of the fahrenheit thermometer scale for every fifty or sixty feet of descent. if the above rate of increase continues uniform the temperature of the crust would be sufficiently hot to boil water at a distance of about , feet below the surface, while at a depth of about thirty miles the temperature would be sufficiently high to melt all known substances at ordinary conditions of atmospheric pressure; that is, to melt all known substances if they were subjected to such a temperature at the level of the sea. in considering the above we must not lose sight of the fact that this increase in temperature with descent below the surface of the earth's crust occurs, not only in places where there are volcanoes, but over all parts of the earth, thus seeming to point out that there is something hot below the surface which fills the entire inside of the earth. it is true the greatest distance to which man has actually gone down through the earth's crust is but a few miles. we do not, therefore, know by actual experience that the interior is anywhere in a fused condition, yet the escape of lava or molten rocks in all latitudes, and in the enormous quantities referred to above, seems to show that the entire inside of the earth is at a temperature sufficiently high to melt all known substances under ordinary conditions. it may be interesting in this connection to examine some of the proofs of this increase in temperature with descent below the surface. the following figures are given by dana: borings to great depths have been made in various parts of the earth, both for artesian wells as well as for the shafts of mines. after passing the line of invariable temperature, the rate of increase for a total distance of , feet below the surface is in the neighborhood of from one degree for fifty-five to sixty feet, or an average of fifty-seven and a half feet for each degree of heat. in the case of the deep artesian well bored at grenelle, paris, where a temperature of eighty-five degrees fahrenheit was reached at a distance of , feet, the rate of increase was somewhat more rapid, being one degree fahrenheit for every sixty feet. in a deep well bored in a salt mine at neusalzwerk, prussia, a depth of , feet showed a temperature of ninety-one degrees fahrenheit at the bottom. this was at the rate of one degree for every fifty feet of descent. at schladenbach, in prussia, a well has been dug to the depth of , feet with a temperature of ° f. a boring at wheeling, in west virginia, reached a depth of , feet, , feet below the level of the sea. here the rate of increase of temperature in the upper half was one degree fahrenheit for every eighty feet, and in the lower half of one degree for every sixty feet. it must not be supposed because the rate of increase of temperature is not uniform that the argument of a highly heated interior is weakened. on the contrary, it would be very surprising if the rate continued uniform; for it is evident that the conducting power of different materials in the earth's crust for heat must necessarily make a great difference in the rate at which heat should increase, as we go farther down into the earth. this is so important a matter that i will explain it at somewhat greater length. let us suppose that instead of the highly heated interior of the earth, we consider the simple case of a hot stove, the doors or other openings into which are closed so that it is impossible to see the red hot coals inside. now, suppose holes were bored in the sides of this stove not deep enough to reach the red hot mass within, and that tightly fitting rods or plugs all of the same length and thickness, but of different kinds of materials such as wood, earthenware, glass, iron, copper, silver, and gold, etc., were so placed in the holes as to tightly fit them. now, under these circumstances the end of all the plugs would be at the same distance from the heated inside. they would not, however, by any means show the same temperatures, the metallic rods would be too hot to touch, while the end of the piece of wood would hardly be hot enough to burn the hand when held against it. the piece of glass and earthenware though less cool would be much less hot than the different rods of metals. their temperatures would be necessarily affected by their conducting power for heat. the wood, the glass, and the earthenware being poorer conductors than the metals would show much lower temperatures. now, the same thing is true with the different materials that constitute the rocks of the earth's crust. some of these are much better conductors of heat than others, so that the rate of increase of temperature with descent below the surface must necessarily vary with the kind of materials that form the crust of different parts of the earth. you may, therefore, safely conclude that the entire interior of the earth is in a highly heated condition, and that the source of this heat is to be traced to the heat the earth originally possessed when, in accordance to the nebular hypothesis of laplace, it was separated from the sun which gave birth to it, that the present crust of the earth has been formed on the outside by the loss of a portion of this heat. the rapidity with which a body cools, depends, among other things, on the difference between its temperature and that of the medium in which it is placed. the greater this difference of temperature the greater the rapidity of cooling. careful measurements made by tait, the english physicist, show that our earth loses every year from each square foot of surface, an amount of heat that would be able to raise the temperature of one pound of water from the melting point of ice to the boiling point of water, or from ° f. to ° f. the rate of loss of heat, must, therefore, have been much greater when the earth was more highly heated than it is now, and will be much smaller than now many years from the present. now, let us suppose, what nearly everyone acknowledges to be true, that the earth was originally so hot as to be a molten globe, and that while in this molten condition, it began to revolve or move around the sun. since the empty space through which the earth moves is very cold, something in the neighborhood of ° below the zero of the fahrenheit thermometer scale, the loss of heat would take place very rapidly and a thin crust of hardened materials would be formed on the outside. now all the time the earth is cooling, it is shrinking or growing smaller. a very little thought will convince you that this cooling or shrinkage could not go on uninterruptedly; for, while the earth was cooling it was contracting, or growing smaller, and in this way a great pressure, or as it is generally called in science, a great stress was being produced. every now and then this stress became so great that the crust of the earth was fractured or broken. at first these fractures would not require a very great amount of stress or force, since the crust of lava was then very thin. after great periods of time, however, the crust grew thicker and thicker, and the amount of force required to break it continually increased, so that the fractures of the crust produced a greater disturbance. whenever the earth's crust was fractured in this way the earth was shaken by what are called earthquakes, while a part of the molten interior would run out or escape, making volcanoes. in the very early times neither the earthquakes or the volcanoes were as energetic as they were at later periods when the thickness of the earth's crust increased. now, having as we believe correctly come to the conclusion that the entire interior of the earth is in a highly heated condition, the next question that arises is as to the present condition of this interior. a long time ago it was believed that the interior of the earth is still melted, and that a cooled portion or crust surrounds a great molten mass that fills all the inside; that it is this mass which supplies the immense quantities of molten rock or lava that escape through the craters of volcanoes or through the fissures in the crust. without going into this question thoroughly, since it is a very difficult question to understand, it will be sufficient to say that there are many reasons why it is impossible to believe that the interior is still melted. you will understand that if the interior of the earth were melted like a huge central sea of fire that each volcano would necessarily affect all the others. now, as we have seen, this is never the case, so that this is one reason we cannot believe in the existence of a melted interior. another reason we cannot believe in a molten interior is an astronomical consideration. it can be shown that under the attraction of the sun and moon the earth could not possibly behave as it does if it were still liquid in the interior. that, on the contrary, the behavior of the earth to the attraction of the sun and moon is such as to make it necessary for us to believe that it is as rigid throughout as would be a globe of steel of the same size. i can easily understand that you find it very difficult to see how it can be believed that the interior of the earth is solid and yet at the same time be sufficiently hot to melt. i can imagine hearing you ask if it is hot enough in the inside to melt any known materials, why it is not melted. the reason, however, is very simple when you come to think it over. for a solid to fuse or become melted, it is not only necessary for it to be heated to a temperature which is different for different substances, but that at the same time it is heated it shall have plenty of room in which to expand or grow bigger. in other words, the temperature required to fuse any substance increases very rapidly with the pressure to which that substance is exposed. now, try to think of the pressure to which the materials that fill the inside of the earth are subjected at great distances below the surface. this pressure is enormous, not only by reason of the weight of the many miles of rocks that are pressing down, but also by reason of the enormous stress or pressure caused by contraction or shrinkage. when we say that the interior of the earth is hot enough to melt all known substances we mean hot enough to melt them if they could be brought from great depths to the level of the sea, but not hot enough to melt them when subjected to the great pressure that exists in regions far below the surface of the earth. briefly, the condition of things is believed to be as follows: the entire interior is filled with rock hot enough to melt at the level of the sea, but under too great pressure to melt. if this be granted, as it is by perhaps the greatest number of men who are competent to judge, the phenomena of earthquakes can be readily explained, as can, indeed, the phenomena of those great movements whereby great changes of level take place in different parts of the earth. now let us see how volcanoes can be explained on the assumption that the interior of the earth is hot enough to melt, but remains solid only because there is no room for the heated mass to expand in. such a heated interior as we have imagined, must be constantly losing its heat and, therefore, shrinking. every now and then this shrinkage must produce great fissures or cracks in the solid crust of the earth. now should such cracks or fissures extend downwards to the heated interior, there must result a decrease in the pressure. the rocks would, therefore, begin to expand and would be forced by the great pressure to rise slowly in such cracks or fissures. the further they rise the greater the relief of pressure, until they at last assume a molten condition in which they are forced out through the craters of volcanoes as molten rocks or lava. but it is not only volcanoes that seem to indicate a highly heated plastic condition as existing in the earth's interior. as geologists well know, there are to be found in the various strata of the earth places where great fissures have been made at various times during the geological past. these fissures vary in width from a few inches to many hundreds of feet, and are frequently scores of miles in length. lava either flows out of them, and covers adjoining sections of the country, or simply rises in them and, afterwards cooling, forms dikes. in many instances, however, the lava is forced in between more or less horizontal layers and in some cases has caused these layers to assume the shape of what geologists know as _subtruderant mountains_. some of the eastern ranges of the rocky mountains have been formed in this manner. we can, therefore, picture to ourselves the following as the manner of formation of an ordinary volcano. a fissure is first formed in the solid crust of the earth, extending downwards to the regions of great heat. there is thus produced a relief of pressure, so that at this point the highly heated rocks begin to be slowly forced up through the fissure. as they rise higher and higher they become less solid and finally expand into fused masses that can flow out of the crater or opening in the earth's surface. in this way a volcano is started. but for this volcano to continue in eruption, it is necessary that the conditions shall continue that force the molten rock upwards from great depths. it is not enough for the lava to fill the crevice that exists upwards to the surface, it must continue to be forced upwards until it escapes. if it is permitted to remain in the fissure for any time, it hardens, and only great dikes are formed. it would seem, therefore, that some other force must be called into action to keep the fissure open or, in other words, to prevent the chilling of the lava. now, this force is generally believed to be the expansive force of steam or the vapor of water. as dana points out, by far the greater part of the vapor which escapes from the craters of volcanoes consists of steam or the vapor of water. indeed, it can be shown that for every hundred parts of different vapors, at least ninety-nine of such parts consist of water vapor. it is for the greater part, to the pressure of steam or water vapor that the escape of lava from the tube near the top of the crater is due. of course, the question arises as to where the water comes from that produces this steam. there are three possible sources. from the rains; from leakage at the bed of the ocean; and from vapors existing at great depths below the surface. it is not probable that either rain water, or water from the ocean, penetrates through the earth's crust for distances much greater than a few thousand feet. it is, however, very well known that in all parts of the earth, except in desert regions, whether they are near or far from the ocean, the rocks are always found fully charged with water. when, therefore, the slowly rising lava passes through the moist rocks that everywhere form the crust of the earth, there must be formed in them great quantities of steam under very high pressure. moreover, many substances, especially those forming lava, possess the power of absorbing large quantities of steam and other gases. therefore, as the molten material reaches the moist rocks in the earth's crust, it becomes highly charged with steam, and as the lava rises towards the surface this steam expands. where the lava is in a very fluid condition the steam quietly escapes, as does the steam from the surface of boiling water. but where the lava is viscous, like tar or pitch, great bubbles are formed, which, on their explosion, throw the lava upwards for great distances into the air. we can, therefore, account in this manner for both the non-explosive as well as the explosive type of volcanoes. it must not be supposed, however, that it is the explosive power of steam which is the principal cause of the lava rising upwards from great depths. this is caused by the great pressure or stress set up by the contraction of a cooling crust. the pressure of this steam is added to this pressure which keeps the lava flowing upwards from great depths below. the objection has sometimes been urged that it is impossible to believe the lava comes from a highly heated interior, because, as is well known, lavas are of different types even when coming from the same volcano at different times of eruption. while such an objection would have weight were it believed that the interior of the earth is still in a molten condition, it loses its weight when one believes that the interior is solid. it must, however, be acknowledged that the largest part of the interior of the earth would probably have the same chemical composition if it had ever been in a completely melted condition throughout. i do not doubt you have already concluded that the reason the earth's volcanoes are practically limited to the borders of continents, or to the shores of islands, is the leakage of the ocean waters into the crust at these parts. this was at one time believed by most geologists. that sea water has much to do with such volcanoes as vesuvius there is no doubt, but it is now generally recognized that it is not so much the present outlines of the earth, or the present arrangement of its land and water areas, that determines the distribution of the world's volcanoes. it is rather believed that the location of the lines of fractures along which the earth's volcanoes are found were determined by conditions that occurred long before the earth assumed its present outlines. but there is another explanation that has been suggested as regards the condition of the interior of the earth. judd refers to this explanation as follows: "some physicists have asserted that a globe of liquid matter radiating its heat into space, would tend to solidify both at the surface and the centre at the same time. the consequence of this action would be the production of a sphere with a solid external shell and a solid central nucleus, but with an interposed layer in a fluid or semi-fluid condition. it has been pointed out that if we suppose the solidification to have gone so far as to have caused the partial union of the interior nucleus and the external shell, we may conceive a condition of things in which the stability and rigidity is sufficient to satisfy both geologists and astronomers, but that in still unsolidified pockets or reservoirs, filled with liquefied rock, between the nucleus and the shell, we should have a competent cause for the production of the volcanic phenomena of the globe. in this hypothesis, however, it is assumed that the cooling at the centre and the surface of the globe would go on at such rate that the reservoirs of liquid material would be left at a moderate depth from the surface, so that easy communication could be opened between them and volcanic vents." i must caution you, however, not to think that the above theory of volcanoes is accepted by all scientific men. on the contrary, there are many who believe that the earth is solid throughout because it has completely lost its original heat; that it is only comparatively small areas that are to be found filled with molten or at least highly heated material. but these opinions are held largely by those who have given their attention almost entirely to the phenomena of earthquakes, or who base their reasonings on mathematical grounds only and have not sufficiently considered the phenomena of volcanoes. since, however, they can be better understood after we have explained the phenomena of earthquakes, we will defer their discussion to the last chapters of this book. chapter xx some forms of lava in describing the wonders of volcanoes, we must not fail to say something of the many remarkable forms that lava is capable of assuming. all volcanic lavas contain large quantities of an acid substance known as _silica_, or what is known better as _quartz sand_. this material exists in lava combined chemically with various substances called bases, the principal of which are alumina, magnesia, lime, iron, potash, and soda. although there are many kinds of lava, yet all lavas can be arranged under three great classes according to the quantity of silica they contain. _acid lavas_ are those in which the quantity of silica is greatest. in these lavas the silica, which varies from to %, is combined with small quantities of lime or magnesia, and comparatively large quantities of potash or soda. some of the most important varieties of acid lavas are known as _trachytes_, _andesites_, _rhyolites_, and _obsidians_. _basic lavas_ are those containing from to % of silica. they are rich in lime and magnesia, but poor in soda or potash. some of the most important of basic lavas are the _dolerites_ and _basalts_. generally speaking, basic lavas are of a darker color than acid lavas, and fuse at much lower temperatures. _intermediate lavas_ are those containing silica in the proportion of from to %. while the temperature of liquid lava has not been very accurately determined, yet, since we know that molten lava is able to melt silver or copper, its temperature must be somewhere between , ° f. and , ° f., the melting point varying with the chemical composition. according to dana lavas can be divided into the following classes according to their fusibility; i. e., _lavas of easy fusibility_, such as _basalts_; these lavas fuse at about , ° f.; _lavas of medium fusibility_, including andesites; these lavas fuse at about , ° f.; _lavas of difficult fusibility_, such as trachytes; these lavas fuse at about , ° f. but what is, perhaps, most curious about lavas is that when the surface of a freshly broken piece of cold lava is carefully examined, it is found to contain a number of small crystals of such mineral substances as quartz, feldspar, hornblende, mica, magnetite, etc. the best way to study the different forms of lava crystals is to prepare a thin transparent slice of hardened lava and then examine it with a good magnifying glass. it will be found that the slice consists of a mass of a glass-like material through which the crystals are irregularly distributed, not unlike the raisins and currants in a slice of not over rich plumcake. when examined by a more powerful glass, such as a microscope, cloudy patches can be seen distributed irregularly through the glass-like mass. when these patches are examined by a higher power of the microscope they are seen to consist of small solid particles of definite forms known as _microliths_ and _crystallites_. it has been shown by a careful study of these minute objects that they form the exceedingly small particles of which crystals are built up. if we fuse a small quantity of lava and then let it slowly cool, the glassy mass will be found to contain numerous crystallites. on the other hand, when fused lava is permitted to cool quickly, it takes on the form of a black, glass-like mass known as _obsidian_ or _volcanic_ glass, a very common form of lava in some parts of the world. in some lavas there are found larger crystals that appear to have been separated from the glassy mass, under the great pressure that exists in the subterranean reservoirs at great depths below the volcanic crater, and then floated to the surface surrounded by the glass-like material. now when we examine these crystals with a higher power of the microscope, we frequently find in them minute cavities containing a small quantity of liquid and a bubble of gas, thus causing them to resemble small spirit levels. the liquid in such cavities has been examined chemically and in most cases has been found to consist of water containing several salts in solution. sometimes, however, the liquid consists of liquefied carbonic acid gas. these wonderful things will be discussed at greater length in the wonder book of light. when the mass of molten rock or lava that comes out of the crater of a volcano is thrown upwards in the air the condition it assumes by the time it falls back again to the earth depends on the height it reaches. if this height is great the lava chills or hardens before reaching the earth, and assumes various forms according to the size of the fragments. the largest of these fragments are called _cinders_; the finer particles _volcanic dust_; while most of those of intermediate particles are known among other things as _volcanic ashes_. we have already seen that when an explosive volcanic eruption occurs there is suddenly thrown out of the crater of the volcano a huge column of various substances that rises sometimes as high as , feet or even more. the smaller fragments of lava are quickly cooled and form volcanic ashes, sand, cinders, or dust. these are rapidly spread out by the wind in the form of a black cloud, that not only covers the mountain but reaches out over the surrounding country, completely shutting off the light of the sun. from this cloud particles of red hot ashes, cinders, sand, etc., begin to fall, the largest particles near the crater of the volcano, and the smaller particles at much greater distances. in very powerful explosive volcanic eruptions such as krakatoa, the finer dust may be carried to practically all parts of the world. volcanic ashes consist of a fine, light, gray powder. these particles take the name ashes from their resemblance to the ashes left after the burning of pieces of wood or coal in an open fire. the name, however, as geicke points out, is unfortunate, since it is apt to lead one to suppose that volcanic ashes consist of some burned material. such an idea is erroneous, however, since ashes do not consist of anything that is left after burning, but merely of fine particles of molten rock that have hardened by cooling. when in the shape of what is known as volcanic dust these particles are so exceedingly small that they can readily make their way through the smallest openings in a closed room just as does the finest dust in the rooms of our houses when they are shut up. there are cases on record where people have been suffocated by the entrance of volcanic dust in closed rooms to which they have fled for safety during volcanic eruptions. _volcanic sand_ consists of the coarser particles of chilled lava that are partly round and partly angular. they are of various sizes up to that of an ordinary pea. volcanic sand is formed by the breaking up of the lava by the explosion of the vapors as they escape from the lava on relief from pressure. volcanic dust when examined by the microscope is found to consist of very small particles that are more or less crystalline. but besides the above there are larger fragments known as _lapilli_, consisting of rounded or angular bits of lava varying in size from that of a pea to an ordinary black walnut. these sometimes consist of solid fragments, but are usually porous, sometimes so much so that they readily float on water. a curious form sometimes assumed by lava consists of what are called _volcanic bombs_. these are formed during explosive eruptions, when masses of liquid lava are hurled high up into the air. during their flight they take on a rotary motion, which tends to make them globular, so that cooling, while still revolving, they assume the form of a more or less spherical mass. at times, however, they are still sufficiently soft when they strike the earth to be flattened out in the form of flat cakes. when of a spherical form these are very properly called volcanic bombs. that volcanic bombs have actually been subjected to a spinning motion while in the air can sometimes be shown by the fact that masses of scoriæ are frequently found in the interior with air cells largest at the centre of the bomb. volcanic bombs are sometimes thrown from the crater to great distances. during one of its recent eruptions, cotopaxi threw out bombs that fell at a distance of nine miles from the crater. according to dana another form of lava bombs is sometimes found on the slopes of the active volcanoes of hawaii, where masses of lava acquire a ball-like shape while rolling down an inclination. what are sometimes called volcanic bombs, but which are more properly _volcanic vesicles_, are produced by small fragments of lava which are thrown up in the air for only a moderate height and, on cooling, assume pear-like forms. fig. represents the appearance of volcanic vesicles. the direction in which these vesicles moved through the air while in a molten state is indicated by their shape, the blunt end being the end towards which the particles were projected. [illustration: fig. . volcanic vesicles _from dana's manual of geology_] but by far the greater portion of the hardened lava; i. e., the coarser, heavier particles, fall back on the mountain, and collecting around the crater build up volcanic cones, as already described in the case of mountains of the vesuvian type. there are two different ways in which the melted lava is broken up into fine particles when it is thrown upwards from the crater of the volcano. nearly all lava contains large quantities of steam that are shut up, or occluded in the mass, being prevented from escaping by reason of the pressure to which the lava is subjected. the lava is released from this pressure as it is thrown out of the crater. the steam or gases escape explosively and thus break the lava into fine liquid spray, which rapidly hardens. there is another way in which small particles of lava are formed. sometimes large pieces of hardened lava are shot upwards into the air with a velocity as great as that with which a heavy projectile leaves the muzzle of a large gun. these heavy particles striking against one another, either while rising or falling, are broken into smaller fragments. sometimes, indeed, these fragments fall back again into the crater from which they are again violently thrown out, and are again broken into smaller fragments either while rising or falling. you will, probably, remember several instances of volcanic eruptions where masses of rock were thrown violently up into the air out of the crater. these larger masses are known as _volcanic blocks_. they probably consist of masses of hardened lava that have collected in the tube of the volcano during some of its periods of inactivity. sometimes, however, they consist of fragments of rocks that are not of volcanic origin. cases are on record where volcanic blocks have been thrown out of the craters in so great quantities as to cover the surface of many square miles of land with fragments hundreds of feet deep. there is sometimes formed on the surface of a pool of lava as it collects in the craters of such volcanoes as mt. loa or kilauea, when the volcanoes are not in eruption, a material resembling froth or scum. the same thing sometimes occurs on the surface of some kinds of lava as it runs down the side of the mountain. in this way a very light variety of highly cellular lava known as _pumice stone_ is produced. the action which thus takes place is not unlike that which occurs during the raising of a lot of the dough from which bread is made, where the carbonic acid gas which is formed during the raising of the dough expands, and produces the well-known open cellular structure of well-raised bread. in the case of pumice stone, however, this raising goes on to such an extent that the mass consists often of less than % of solid matter, the remainder being a tangled mass of air. [illustration: the lava flow of the crater of kilauea, hawaiian islands _from a stereograph, copyright, by underwood & underwood_] fragments of lava that possess a cellular structure form what are known as _scoriæ_. the lightest of all kinds of scoriæ is what is known as _thread-lace scoriæ_. here the thin walls consist of mere threads. figs. and represent the appearance of thread-lace scoriæ from kilauea. the separate threads are very fine, being only from one-thirtieth to one-fortieth of an inch in thickness. as can be seen, this form of scoriæ have six-sided or hexagonal shapes. you can form some idea of the great lightness of such scoriæ when you learn that they contain only . % of rocky material. indeed, they contain so little solid material that a layer of volcanic glass only one inch thick, if blown out into scoriæ, would be able to produce a layer sixty inches thick. [illustration: fig. . thread-lace scoriÆ from kilauea _from dana's manual of geology_] another curious form sometimes assumed by lava, especially in the case of kilauea, is where the lava is spun out in the form of long silk-like hairs. this is called by the natives _pele's hair_, after the name of their goddess. inasmuch as the origin of this form of lava was at one time generally attributed to the action of the wind in drawing out thread-like pieces from the jets of lava thrown upwards from the pool, it will be interesting if its true cause is explained. [illustration: fig. . thread-lace scoriÆ from kilauea _from dana's manual of geology_] dutton, in his report on the hawaiian volcanoes, refers to the formation of pele's hair as follows: "the phenomenon of pele's hair is often spoken of in the school books, and receives its name from this locality. it has generally been explained as the result of the action of the wind upon minute threads of lava drawn out by the spurting up of boiling lava. nothing of the sort was seen here, and yet pele's hair was seen forming in great abundance. whenever the surface of the liquid lava was exposed during the break-up the air above the lake was filled with these cobwebs, but there was no spurting or apparent boiling on the exposed surface. the explanation of the phenomenon which i would offer is as follows: liquid lava coming up from the depths always contains more or less water, which it gives off slowly and by degrees, in much the same way as champagne gives off carbonic acid when the bottle is uncorked. water-vapor is held in the liquid lava by some affinity similar to chemical affinity, and though it escapes ultimately, yet it is surrendered by the lava with reluctance so long as the lava remains liquid. but when the lava solidifies the water is expelled much more energetically, and the water-vapor separates in the form of minute vesicles. since the congelation of all siliceous compounds is a passage free from a liquid condition through an intermediate state of viscosity to final solidity, the walls of these vesicles are capable of being drawn out as in the case of glass. the commotion set up by the descending crust produces eddies and numberless currents in the surface of the lava. these vesicles are drawn out on the surface of the current with exceeding tenuity, producing myriads of minute filaments, and the air, agitated by the intense heat at the surface of the pool, readily lifts them and wafts them away. it forms almost wholly at the time of the break-up. the air is then full of it. yet i saw no spouting or sputtering, but only the eddying of the lava like water in the wake of a ship. the country to the leeward of kilauea shows an abundance of pele's hair, and it may be gathered by the barrelful. a bunch of it is much like finely shredded asbestos." you have probably often seen the beautiful frost pictures that collect on the panes of glass in a room where the ventilation has been neglected. these pictures consist of groupings of ice crystals that collect on the surface of the windows, when the moist vapor-laden air in the room is chilled by contact with their cold surfaces. now the crystals formed in cooling lavas are sometimes grouped in forms closely resembling frost pictures. a few of such forms are represented in figs. and in lava from mt. loa and mt. kea. [illustration: fig. . frost-like lava crystals _from dana's manual of geology_] [illustration: fig. . frost-like lava crystals _from dana's manual of geology_] certain varieties of lava, especially that which is found in dikes, form cool, beautiful columns called basaltic columns. they are due to the contraction that occurs on the cooling of the material. instances of basaltic columns are seen in the giant's causeway, on the northern coast of ireland, as well as in the isle of cyclops on the coast of italy. the general appearance of the latter is represented in fig. . [illustration: fig. . basaltic columns, isle of cyclops, italy] it is a curious fact that the entire mass of basalt does not generally take the columnous form but only certain layers which terminate suddenly above and below at structureless masses of basalt, as shown in fig. . these columns, however, are always found at right angles to the cooling surfaces as seen in the figures. they may, therefore, be inclined at all angles to the horizon. [illustration: fig. . columnar and non-columnar basalt] when molten lava is only thrown up a short distance into the air from a crater it is still partially molten when on falling it again reaches the earth, and therefore clings to any surface on which it falls. there are thus built up curious cones known as _driblet cones_, in which the separate drops covering the sides of the cone can be distinctly traced. driblet cones are represented in figs. and . here, as can be seen, the separate drops can be readily traced as they run down a short distance before cooling. [illustration: figs. , . driblet cones _from dana's manual of geology_] we have already referred briefly to the _lava caves_ or _grottoes_, that are formed in some of the lava streams issuing from vesuvius, etna, or hawaii. these caves consist either of a number of communicating huge bubbles, or of the tunnels that are formed in the lava by the hardening of the outside of the lava streams as they flow down the sides of the mountain, and towards the close of the eruption are afterwards emptied by the molten lava within continuing to flow to a lower level before solidifying. now, in the interior of these caves, there are often found on the walls, as well as on the portions of the floors of the caves, immediately below them, curious pendants, like icicles, or, more correctly, like the _stalactites of limestone_ that are seen hanging to the walls of caves in limestone districts, where they are formed as follows: as the rain water sinks through limestone strata it dissolves some of the lime, when, slowly falling, drop after drop, from the roofs of the caverns, small particles of lime are deposited on the roof, and in this manner a pendant of limestone is formed. the water that falls to the floor of the causeway immediately below, also builds up a dome-like hillock called a stalagmite. in due time the pillar reaches downwards, and the opposite hillock upwards until the two meet, thus forming great natural pillars that appear to hold up the roof of the vast cave in which they have been slowly formed. a number of _lava stalactites_ are represented in fig. . [illustration: fig. . lava stalactites _from dana's manual of geology_] now, in a similar manner these lava stalactites, formed in the lava caves or grottoes, are caused by the stream as it escapes from the walls of the caves depositing on them stalactites of various lava minerals it has dissolved as it slowly passed through them. but the most important of all volcanic products is _volcanic dust_. this, as we have seen, is so light that it remains longest in the air, and is often carried by the winds to great distances from the volcano from which it escaped. it may interest you to know that some of the most fruitful of the great wheat fields of the western parts of the united states owe their extraordinary fertility to immense deposits of volcanic dust that have been thrown out from some of the great volcanoes of the geological past, now found in an extinct condition in these parts of the united states. according to russell, immense deposits of volcanic dust are spread over vast areas in montana, southern dakota, nebraska, and kansas, as well as over parts of oregon, and washington, and, indeed, over large areas of southwestern canada and alaska. it is practically certain that many of the eruptions producing this dust occurred within historic times. there must, therefore, have been many times in these parts of our country when the dense ash clouds hiding the sun turned the day into night and destroyed the forests and other vegetation by showers of red hot ashes. there were produced, too, the same great dread, and possibly loss of life as common during historical eruptions. it is pleasing, however, to think that while these great catastrophes brought suffering and dread to the people who then lived on the earth, they were, nevertheless, but the forerunners of those fruitful fields that at a much later age were to bless the people who afterwards lived on them. chapter xxi mud volcanoes and hot springs mud volcanoes are the more or less conical hillocks from which, under certain conditions, mud is thrown out through the crust of the earth. geikie defines mud volcanoes as follows: "conical hills formed by the accumulation of fine and usually saline (salty) mud, which, with various gases, is continuously or intermittently given out from the orifice or crater in the centre. they occur in groups, each hillock being sometimes less than a yard in height, but ranging up to elevations of feet or more. like true volcanoes, they have their periods of repose, when either no discharge takes place at all, or mud oozes out tranquilly from the crater, and their periods of activity, when large volumes of gas, and sometimes columns of flame, rush out with considerable violence and explosion, and throw up mud and stones to a height of several hundred feet." there are two kinds of mud volcanoes: those in which the mud is thrown out by the action of different kinds of gases, and those in which the mud is thrown out by the action of steam. mud volcanoes may or not be volcanic phenomena. those which occur in the neighborhood of volcanoes whether active, dormant, or extinct, are probably of volcanic origin. there are others, however, which occur in regions far removed from volcanoes. these are probably due not to volcanoes, but to chemical action and the eruptions are caused by the action of gases. the gases producing these eruptions are either carbonic acid gas (the gas that is given off from soda water); carburetted hydrogen (the gas that is sometimes seen escaping from the bottom of marshy ground); sulphuretted hydrogen (a gas that is given off from rotten or decomposing eggs, and possessing the characteristic odor of decayed eggs) and nitrogen gas derived from the atmosphere. in mud volcanoes of the gaseous type the mud is generally cold, and the water salty. in this latter case the mud volcanoes are also called _salses_. daubeny has pointed out that the mud volcanoes of this class that occur in the neighborhood of sicily are due to the slow burning or oxidation of beds of sulphur. mud volcanoes which eject hot mud by the force of eruption of steam, which occur in volcanic districts, are of volcanic origin. they are caused by the passage of hot water and steam through beds of volcanic rock such as tufa, or hardened volcanic mud and other volcanic products. the hot water or steam raises the temperature of the mud through which it passes to the boiling point. as dana remarks, the mud varies in consistency from very liquid muddy water to a thick mass like boiling soap, or in some cases like masses of mud or paint, and, in still other cases, to material like soft mortar, the consistency of the mud varying with the dryness of the season. there are three regions where mud volcanoes are especially common. one of the best known is in the yellowstone national park, four miles north of yellowstone lake, and six miles from crater hill. some of these mud volcanoes have circular craters about ten feet in depth around which they have built mounds, the rims of which are several feet above the general level. there are well-known regions of mud volcanoes in different parts of iceland. here, according to lyell, they occur in many of the valleys where sulphur vapor and steam bursts from fissures in the ground with a loud hissing noise. in these regions there are pools of boiling water filled with a bluish black clay-like paste, that is kept violently boiling. huge bubbles, fifteen feet or more in diameter, rise from the surface of the boiling mass. the volcanoes pile up the mud around the sides of their craters or basins. another part of the world where mud volcanoes are especially numerous is on the western shores of the caspian sea at a place called baku. these are of the gaseous type and are attended by flames that blaze up to great heights often for several hours. these flames are due to the presence of natural gas and petroleum vapor that pass out through the water. large quantities of mud are thrown out from the craters of these mud volcanoes. there are also many mud volcanoes in a district in india about miles northwest of cutch near the mouth of the indus. in this region the cone built up around the crater is sometimes as high as feet. the following description of mud volcanoes on java is quoted from daubeny's book on volcanoes. "it would appear likewise from dr. horsfield's description, that java exhibits phenomena of a similar kind to those noticed in sicily and at the foot of the apennines, and there known under the name of 'salses.' in the calcareous district (which i suspect to belong to the same class of formations as the blue clay and tertiary limestone of sicily) occur a number of hot springs, containing in solution a large quantity of calcareous earth, which incrusts the surface of the ground near it. of these, some are much mixed with petroleum, and others highly saline. "the latter are dispersed through a district of country consisting of limestone, several miles in circumference. they are of considerable number, and force themselves upwards through apertures in the rocks with some violence and ebullition. the waters are strongly impregnated with muriate of soda, and yield upon evaporation very good salt for culinary purposes (not less than tons in the year). "about the centre of this limestone district is found an extraordinary volcanic phenomenon. on approaching the spot from a distance, it is first discovered by a large volume of smoke rising and disappearing at intervals of a few seconds, resembling the vapors arising from a violent surf, whilst a dull noise is heard like that of distant thunder. having advanced so near that the vision was no longer impeded by the smoke, a large hemispherical mass was observed, consisting of black earth mixed with water, about sixteen feet in diameter, rising to the height of twenty or thirty feet in a perfectly regular manner, and, as it were, pushed up by a force beneath, which suddenly exploded with a dull noise, and scattered about a volume of black mud in every direction. after an interval of two or three, or sometimes four or five seconds, the hemispherical body of mud or earth rose and exploded again. "in the same manner this volcanic ebullition goes on without interruption, throwing up a globular mass of mud, and dispersing it with violence through the neighboring places. the spot where the ebullition occurs is nearly circular and perfectly level; it is covered with only the earthy particles impregnated with salt water, which are thrown up from below; its circumference may be estimated at about half an english mile. in order to conduct the salt water to the circumference, small passages or gutters are made in the loose muddy earth, which lead it to the borders, where it is collected in holes dug in the ground for the purpose of evaporation. "a strong, pungent, sulphurous smell, somewhat resembling that of earth-oil (naphtha), is perceived on standing near the site of the explosion, and the mud recently thrown up possesses a degree of heat greater than that of the surrounding atmosphere. during the rainy season these explosions are more violent, the mud is thrown up much higher, and the noise is heard at a greater distance. "this volcanic phenomenon is situated near the centre of the large plain, which interrupts the great series of volcanoes, and owes its origin to the same general cause as that of the numerous eruptions met with in this island." there are, in many parts of the world, springs, whose waters issue from their reservoirs at temperatures either at or near the boiling point of water. these are called _hot_ or _thermal springs_. hot springs are found both in volcanic regions, as well as in regions where there are no volcanoes, but where there are lines of deep fissures or faults. according to dana, in both of these classes, the cause is to be traced to heat of volcanic or deep subterranean origin. hot springs are also found in regions where there are no volcanoes. in these cases the heat is due to the gradual oxidation of various sulphide ores, or to some other chemical action. the waters of hot or thermal springs almost always contain various mineral substances in solution. all spring water contains some little dissolved mineral matter, but in hot springs the quantity of this matter is greater than in cold springs, because hot water can dissolve mineral substances much better than can cold water. it might surprise you to hear that one of the commonest substances that is found in solution in the waters of many hot springs is silica; for silica is practically sand, and sand does not easily dissolve in water as does sugar. the very hot water, however, which comes from the hot spring, whose temperature below the earth's surface is very much higher than it is when it comes out of the spring, possesses the power of readily dissolving silica from the rocks over which it flows. when the waters of such springs reach the surface the silica is deposited in a solid condition around the outlets of the springs. in this way there are built up craters or mounds, or, more correctly, crater-shaped basins. sometimes the hot water contains calcareous substances dissolved in it, the solution being caused not only by reason of the hot water, but also by means of the carbonic gas it contains. when this water flows from the springs, it builds up the same crater-shaped mounds, only in this case the mounds are of lime instead of silica. there are peculiar kinds of hot springs called _geysers_, that possess the power of throwing huge streams of water up into the air at more or less regular intervals. the word geyser is an icelandic word meaning to rage, or snort, or gush, the name being given by reason of the manner in which the waters rush violently out during an eruption. as dana points out, when the water in a basin of a hot spring merely boils, whether this boiling is nearly continuous, or the water is alternately boiling and quiet, the spring is called a hot or thermal spring, but where the water is thrown violently out at more or less regular intervals, it is called a geyser. the cause of the eruption of a geyser was discovered by professor bunsen, the celebrated german chemist, after a careful study of the geyser regions in iceland. the waters of geysers contain large quantities of either silica or lime in solution. bunsen traced the cause of these curious eruptions to be the manner in which the hot springs pile up cones of silica or limestone around their mouths. the water of a geyser generally issues from the top of a more or less conical hillock, reaching the surface through a funnel-shaped tube. both the tube and the basin are covered with a smooth coating of silica or limestone. in the case of the great geyser in iceland, the basin is over fifty feet high and seventy-five feet deep. both the tube and the basin have been slowly deposited by the hot water of the geyser. it is only when the tube of a geyser has reached a certain depth that the geyser is able to erupt. moreover, as soon as this tube passes a certain depth the geyser can no longer erupt and forever afterwards becomes an ordinary hot spring. there are, therefore, to be found in most geyser regions, a number of what might be called young geysers or merely hot springs, that are not yet deep enough to erupt; others that have just commenced eruption, others that have reached their prime, while others that, old and decrepit, have again merely become hot springs. let us now try to understand the cause of the eruption of a geyser. bunsen's explanation, which is now generally accepted, is as follows: the heat of the volcanic strata through which the tube of the geyser extends, gradually raises the temperature of the water that fills the geyser tube. since the boiling point of a liquid increases with the pressure to which it is subjected, far down in the tube of a geyser, the pressure arising from the weight of the water above it is sufficiently great to prevent the water from beginning to boil until it reaches a temperature far higher than that at which it would boil in the upper parts of the tube. suppose now, when the water in the funnel-shaped tube is nearly filled to the top, the water at last grows hot enough to begin boiling at some point near the middle of the tube. the pressure of the steam driven off from this portion of the water raises the column of water above it in the tube and begins to empty it out of the top of the geyser. all the water below this point being thus suddenly relieved of its pressure, and being now much hotter than is necessary to boil the water at that decreased pressure, suddenly flashes into steam, and violently shoots out all the water above it to a height that in some cases may be as great as to feet. the steam causes this eruption, then rushes out with a roar, and the geyser eruption is over. professor tyndall in his charming book entitled "heat as a mode of motion" speaks as follows concerning professor bunsen's discovery: "previous to an eruption, both the tube and basin are filled with hot water; detonations which shake the ground, are heard at intervals, and each is succeeded by a violent agitation of the water in the basin. the water in the pipe is lifted up so as to form an eminence in the middle of the basin, and an overflow is the consequence. these detonations are evidently due to the production of steam in the ducts which feed the geyser tube, which steam escaping into the cooler water of the tube is there suddenly condensed, and produces the explosions. professor bunsen succeeded in determining the temperature of the geyser tube, from top to bottom, a few minutes before a great eruption; and these observations revealed the extraordinary fact that at no part of the tube did the water reach its boiling point. in the sketch [not reproduced] i have given on one side the temperatures actually observed, and on the other side the temperatures at which water would boil, taking into account both the pressure of the atmosphere and the pressure of the superincumbent column of water. the nearest approach to the boiling point is at a, a height of feet from the bottom; but even here the water is ° c., or more than - / ° f., below the temperature at which it could boil. how then is it possible that an eruption could occur under such circumstances? "fix your attention upon the water at the point a, where the temperature is within ° c. of the boiling point. call to mind the lifting of the column when the detonations are heard. let us suppose that by the entrance of steam from the ducts near the bottom of the tube, the geyser column is elevated six feet, a height quite within the limits of actual observation; the water at a is thereby transferred to b. its boiling point at a is . °, and its actual temperature . °; but at b its boiling point is only . °, hence, when transferred from a to b the heat which it possesses is in excess of that necessary to make it boil. this excess of heat is instantly applied to the generation of steam: the column is thus lifted higher, and the water below is further relieved. more steam is generated; from the middle downwards the mass suddenly bursts into ebullition, the water above, mixed with steam clouds, is projected into the atmosphere, and we have the geyser eruption in all its grandeur. "by its contact with the air the water is cooled, falls back into the basin, partially refills the tube, in which it gradually rises, and finally fills the basin as before. detonations are heard at intervals, and risings of the water in the basin. these are so many futile attempts at an eruption, for not until the water in the tube comes sufficiently near its boiling temperature, to make the lifting of the column effective, can we have a true eruption." the principal geyser regions of the world are in iceland, in new zealand, and in the yellowstone national park in the united states. there are several geyser regions in iceland. the best known lies in the neighborhood of mt. hecla. here is a great geyser that shoots up a column of water to a height of about feet every thirty hours. fig. represents the appearance of the crater of the great geyser in iceland. [illustration: fig. . crater of the great geyser of iceland] it is a well-known fact that in geyser regions generally, the throwing of stones or other materials into the tube will frequently hasten an eruption. this is probably due to the fact that the throwing in of these things results in the raising of the water in the tube, thus hastening the eruption. the new zealand region is in the neighborhood of lake rotomahama in the northern island. the geyser region in the yellowstone park is by far the most interesting of all geyser regions. this region is situated principally around fire-hole fork of the madison, and near shoshone lake at the head of lake fork of the snake river. there are many geysers in this region, as well as simple hot springs. the temperature of their waters varies from between ° and ° f. to the boiling point of water at this elevation. as you are probably aware, water boils at the temperature of ° f. only under the condition of the ordinary atmospheric pressure that exists at the level of the sea. at higher elevations, such as on the slopes of mountains, or on high plateaus, water boils at a lower temperature. the height of the country in which the yellowstone park is situated is so great that the water boils at temperatures of from ° to ° f. the conical hillock of geyser cones from which the waters flow assume various shapes, two of which are shown in figs. and . [illustration: fig. . giant geyser _from dana's manual of geology_] [illustration: fig. . bee hive _from dana's manual of geology_] that shown in fig. represents the shape of the cone of the giant geyser in the upper geyser basin of the fire-hole, yellowstone national park. this cone is about ten feet in height, and twenty-four feet in diameter. as shown in the figure it is broken on one of its sides. it throws out, at long intervals, a column of water the height of which varies from ninety to feet. fig. represents the crater of a cone known as the bee hive in eruption. besides the above named geyser regions there is another region on the shores of celebes, and a small region on san miguel, in the azores islands, in the atlantic ocean. besides hot springs and mud volcanoes there are two other phenomena connected with volcanic action that we will now briefly describe. when eruptions take place and the lava begins to flow down the side of a mountain, the different vapors and gases with which the lava is charged begin to escape or pass out from the boiling or fused mass. when these substances are of such a character that they produce fumes, or the vapors of various chemical substances, that become solid on cooling, they form what are called _fumaroles_, a word derived from a latin word meaning "to smoke." for the greater part, fumaroles are found on the edge of craters, but sometimes are found in cavernous places either in the crater or in the lava streams. there is, still, another class of openings through which only sulphurous vapors escape. these are called _solfataras_, a word derived from the italian word _solfo_, or sulphur. solfataras are generally found in regions distant from volcanic action. in the materials that escape from recently ejected lava, or molten lava, the temperature is high enough to volatilize many of the solid ingredients. but where the temperature is low, only sulphur vapors are driven off. it is for this reason that fumaroles are only found around the craters of active volcanoes, or on the lines of cracks or crevices of the lava stream where the temperature is very high. [illustration: fig. . bee hive geyser of iceland _from dana's manual of geology_] besides water vapor and sulphurous vapors there are other substances that escape from the earth in volcanic districts. sulphurous acid, together with hydrogen and nitrogen escape from nearly all lava. at vesuvius chlorine gas is given off. this, however, as soon as it passes into the atmosphere becomes changed into hydrochloric acid. sulphurous acid is frequently changed into sulphuric acid, which, combining with various substances, forms such materials as _gypsum_, or sulphate of lime, the chemical name for plaster of paris; sulphate of soda or _glauber's salt_; sodium chloride or _common table salt_; and _sal ammoniac_. you will remember in reading the description of vulcano, in the grecian archipelago, that some of these products were collected at the chemical works that had been established on the volcano. when a volcanic mountain is for the time being passing from an active to an extinct condition, it is sometimes said to be in the _fumarole stage_, since the presence of the fumaroles are the only indication of its activity. the volcanic heat is still great. when it reaches a still greater decline, the fumaroles disappear, and only solfataras are left. the amount of heat is now only sufficient to produce sulphur vapors and the vapor of water. this is called the _solfatara stage_. of course, as we have already pointed out, fumaroles and solfataras may occur in the neighborhood of a volcano at different distances from its crater. chapter xxii the volcanoes of the moon there can be no doubt that the moon was once the seat of very great volcanic activity. it was formerly believed that the very many volcanic craters which can be seen on its surface when it is examined by a comparatively small telescope, were all extinct. while this is nearly true, yet recent investigations have shown that in all probability a feeble volcanic activity still exists in a few of these craters. the distinctness with which the surface of the moon is seen does not depend so much on the size of the telescope employed, as it does on the steadiness of the atmosphere when the telescope is being used. when one wishes to examine a very distant body like a star, it is necessary to use a powerful telescope, but in the case of a comparatively near body, like one of the planets or the moon, a big telescope is not necessary. it is, however, necessary to make the observations at some time of the year, or in some part of the world, when the air is apt to be free from winds. a person on the earth's surface looking at the heavenly bodies through a telescope is practically in the position in which he would be were he at the bottom of the water in a large lake looking up through the water at some body in the heavens. he would have no difficulty in seeing such a body distinctly as long as the upper surface of the water remained quiet, and unruffled by waves. as soon, however, as waves were set up, the images seen in the telescope are so distorted as to become practically worthless. it is for this reason that it is customary to build great astronomical observatories in parts of the world where there are apt to be many days in the year when the air is almost entirely free from wind. since the atmosphere is apt to be disturbed by winds in both the temperate and the polar latitudes, these parts of the world are not very satisfactory as sites for astronomical observatories. the conditions are more favorable near the equator, since, although at certain seasons of the year there are very severe storms in these regions, yet there are quite long periods when the air is almost entirely free from winds. it is for this reason that harvard university has erected an astronomical observatory at arequipa, peru, at an elevation of , feet above the level of the pacific ocean. here, with a comparatively small object glass, of about twelve inches aperture, magnificent photographs have been obtained not only of the moon but also of the planet mars. according to professor pickering, from whose magnificent work, entitled, "the moon," much of the information in this chapter has been obtained, the moon, which is generally spoken of as a satellite of the earth, ought rather to be called the earth's twin planet. although the moon appears to revolve in a small elliptical orbit around the earth it should properly be said to revolve around the sun; for, together with the earth, it revolves around the sun once every year. as seen from any of the planets that lie near the earth the earth and moon would appear as a very beautiful double star. in order the more readily to understand what will be said shortly concerning the origin of the moon, it may be mentioned that the moon's diameter is , miles, or a little more than one-fourth the diameter of our earth. you will, most probably, be surprised to learn that the origin of the moon is believed to be very different from the origin of the moons or satellites of jupiter, saturn, and the other planets. as we have already seen, according to the nebular hypothesis, all the planets except the earth probably had their moons formed from the rings that were left surrounding them when they shrunk on cooling to their present dimensions. such a ring is still to be seen surrounding saturn. now it is believed that our moon was formed in a different manner. it was not thrown off from the earth while the latter was in a highly fluid or gaseous condition, but after the earth had shrunken to nearly its present size and, most probably, after a solid crust had been formed on its surface. in order that our earth should be able to violently throw off a large portion of its mass, it is only necessary that at the time this separation occurred, its motion of rotation on its axis was sufficiently great to enable it to make one complete revolution in rather less than three hours instead of in the twenty-four hours it now requires. at this velocity of rotation, objects would fly off the earth in the neighborhood of the equator, under the influence of the high centrifugal force. let us, then, endeavor to see if it was at all probable that the earth ever did turn so rapidly on its axis. you all probably know that it is principally the attraction of the moon that produces the earth's tides. of course, the sun also produces tides on the earth, but it is so far off from the earth that not withstanding its greater mass the tides it forms are much smaller than those produced by the moon. you also know that the moon produces at the same time two tides in every twenty-four hours, on directly opposite sides of the earth; one on the side immediately under the moon, and the other on the side furthest from the moon. as the earth rotates between these two tides, they act as a break which serves to impede its motion. every high tide, therefore, tends to make the earth rotate more slowly, and thus to slowly increase the length of the day. for this reason to-day is a trifle longer than yesterday, and still longer than a day a hundred years ago. you must not suppose for a moment that this increase in the length of the day is large. on the contrary, it is so small that since the year a. d. , up to the present time, the day is only a very small fraction of a second longer. but it was very different in the earth's geological past, when the inside of the earth was in a molten condition; for then great tides were set up in the melted interior of the earth that not only greatly changed the shape of the earth, but decreased the rate of rotation much more rapidly than it does when the earth's tides are limited as they are now to the waters on the earth's surfaces. there was, however, at the same time, something going on that tended greatly to make the earth turn more rapidly on its axis. while the originally melted earth was cooling and shrinking, the rate of its rotation was necessarily increasing. as you know, the time of vibration of a pendulum, that is, the time it requires to make one complete to-and-fro motion, is shorter the shorter the length of the pendulum. a pendulum two feet long moves to and fro more slowly than a pendulum one foot in length. in the same way a rotating sphere will make one complete rotation in a shorter time when its radius, which corresponds to the length of a pendulum, is shorter. therefore, as the earth shrunk, it rotated more and more rapidly, and at last reached a rapidity of motion at which an immense quantity of matter flew off its surface nearest the equator and went out into space, never again to return. it was this mass that constituted the earth's moon. necessarily such a tremendous catastrophe was attended by an earthquake as well as by the most fearful volcanic phenomena that the earth has ever witnessed. the terrible catastrophe produced by the explosive eruption of krakatoa was but as a small drop of rain falling on the earth, when compared with the catastrophe produced when the "five thousand million cubic miles of material left the earth's surface, never again to return to it." it is not known whether this matter was torn off the earth at a single time or during successive times, but quoting the beautiful language of professor pickering: "we may try in vain to imagine the awful uproar and fearful volcanic phenomena exhibited when a planet was cleft in twain, and a new planet was born into the solar system." this terrible catastrophe took place at a time not when the earth was a gaseous mass, but when it had condensed into a comparatively small mass not much larger than it is at its present time, and possibly even after it had hardened sufficiently to form a solid crust on its outside. if you look at a map of the earth on a mercator's projection, such, for example, as that employed in illustrating the distribution of the world's volcanoes in fig. , you can see, even without any very close examination, that the great water area of the atlantic ocean has its eastern and western shores almost parallel to each other, so that if you conceive the eastern and western continents as being pushed together, they would, except at the south, almost completely fit together, and the same thing is true, if greenland is pushed towards the northeastern coast of north america. of course, some portions of the coast would not fit exactly, but then these portions might either have been worn away, or, as is more probable, have been changed in shape by the deposit of immense beds of sedimentary rocks spread over the borders of the atlantic by the great rivers that empty into it. this is so remarkable a fact that it will be well worth your while to turn to the map mentioned and convince yourself of the proof of what i have just said. as you will see, europe and africa would almost exactly fit against south america and north america, while greenland would even more closely fit against the northeastern coast of north america. now, while we do not say that it was so, it has been suggested as just possible that the great depression of the pacific ocean represents the spot that was once filled by the moon. that the eastern and western continents, then torn asunder by the great force of the convulsion, were left floating on the surface of a sea of molten matter, a greatly widened crack marking positions they assumed at the end of this cataclysm. of course, you must understand that all this is a mere supposition, and that we do not know whether the earth was actually cooled on the outside when this occurred, since it might have still been in a liquid condition throughout. it would seem, however, to have occurred rather recently, since it could not have occurred until the earth shrunk so much that it became so small in radius as to acquire a very rapid rate of motion on its axis. it is an interesting fact that we are, perhaps, better acquainted with that side of the moon which is turned towards us than we are with the surface of the earth on which we live. of course, i do not mean in the small details of the moon's surface, but with such portions as can be seen through a good telescope when the air is quiet. while there are no parts of the moon's surface that have not been carefully examined in detail probably thousands of times by acute astronomers, there are still comparatively large areas of the earth that have never been once trodden by civilized man. when i speak of all parts of the moon's surface, i only mean those parts that are turned towards us. you may possibly be ignorant of the fact that the moon always turns exactly the same face towards the earth. not only has no man ever seen the opposite side of the moon, but he never can hope to see it while he remains on the earth. this is because the moon turns or rotates on its axis in exactly the same time that it revolves in its orbit. when i say that the time of rotation is the same as the time of revolution of the moon, i do not mean that it is almost the same, but that it is exactly the same. if it differed even but a small fraction of a second, a time would come when we would be able to see the other side of the moon. now, since astronomers have made careful pictures of the moon, many, many years ago, we can see by comparing them with photographs taken at the present time there has been no change whatever in that face of the moon which is turned towards us, and this, of course, proves beyond question, that the time of the moon's rotation during this great period has remained exactly the same as the time of its revolution. it may possibly seem to you that it cannot be a matter of great importance in a book like this on the wonders of volcanoes and earthquakes, whether or not the moon always turns its face towards the earth; on the contrary, it is a matter of the greatest importance since by it we can prove positively that the moon was at one time at least in a partly fluid condition. it was the presence of this partly fluid interior that resulted in the time of the moon's rotation agreeing exactly with the time of its revolution. the tides of the earth set up in the moon's molten interior, tides, that instead of reaching twice every day the height of a few feet only, were set up in the molten mass in the moon's interior, probably reaching miles in height, rapidly decreased the time of the moon's rotation until the moon rotated once only during every complete revolution. even now that the moon is probably solid throughout, the time of its rotation and revolution exactly agree because, while in a molten condition, the action of the earth changed its shape from that of an exact sphere to a spheroid, with its longest axis in the direction of the earth. even, therefore, if the moon at any time began to rotate faster than the earth, the earth acting on its projecting surface retarded it until the time of its rotation agreed exactly with the time of its revolution. it was at one time believed that the moon had no atmosphere. it is now known, however, that it has an atmosphere. it is true this is a rare atmosphere, probably not greater in density than the one-ten thousandth of the earth's atmosphere. this important question was settled once for all on august th, , at the harvard observatory at arequipa, peru, when a photograph was taken of an object on the moon. it could be readily seen on examining this photograph that the light coming from the moon experienced a bending, known as refraction, in passing from the space outside the moon to its atmosphere on to its surface. of course, when the moon was thrown off from the earth by reason of its great centrifugal force, it carried along with it a portion of the earth's atmosphere. but since the quantity of matter in the moon is only about one-eightieth of that of the earth, the force of gravity on the moon is much smaller than that on the earth, being almost exactly one-sixth that of the earth's gravity. in other words, if you could succeed in reaching the moon's surface, you would only weigh one-sixth of what you weigh on the earth, but then you could carry a weight six times heavier with no greater effort, and, as for running, jumping, and other athletic exercises, the surface of the moon would, indeed, be a great place on which to break records, since one could readily jump six times higher, put the shot six times further, than on the earth, or go through most other athletic exercises with a corresponding increase. without going any further into this question it will be sufficient to say that the moon's present atmosphere is believed to consist of carbonic acid gas, and that while on the general surface of the moon this atmosphere must be very rare, yet, at the bottom of the great fissures that cross the moon's surface, it may possess a fairly great density, especially if the moon still possesses feeble volcanic activity; that carbonic acid gas is still being given off from the inside of the moon as we know it is being given off from inside the earth. under the best conditions of atmosphere and telescope, we can see the moon's surface as it would appear at a distance varying from miles to miles from the earth. with a fifteen-inch telescope, under perfect conditions of vision, objects can be seen as if they were at a distance of miles from the earth, and with the most powerful glasses, and the best conditions of atmosphere this distance can be reduced to about miles. this would enable us to clearly see large objects like rivers, lakes, seas, or forests, if they existed, but would not be sufficient to enable us to see houses, buildings, or roads. when we come to examine the surface of the moon under the most favorable conditions, we find that it is extremely irregular. there are plenty of high mountains. these mountains are not collected in ranges as they are on the earth's surface, but are completely separated from each other, and are scattered in great numbers over the moon's surface. you may form some idea of the number of volcanoes that have been observed on the moon when i tell you that as many as , have been seen on that side of the moon that is turned towards the earth. now it is an interesting fact that almost all these mountains possess great craters that are not unlike some of the volcanic craters we see on the earth. the volcanic craters of the moon, however, are of very much greater size than those on the earth, many being from fifty to sixty miles in diameter, while some of them are more than miles in diameter. smaller craters, say from twenty to twenty-five miles in diameter, can be counted by the hundreds. like most of the moon's craters, the largest crater more closely resembles one of the pit-craters or calderas on the island of hawaii. this volcanic crater consists of a huge circular ring with a small irregular peak that rises inside the ring. this peak, by the way, might at first appear to resemble the crater of vesuvius, which after a long period of inactivity of the mountain during the eruption that destroyed pompeii and herculaneum was thrown up inside of what had been left standing of the old crater of somma. but it has no crater at its summit, and, therefore, resembles rather the irregular pile or rock that rises from the surface of a lava lake in the craters of mt. loa or mt. kilauea in hawaii. besides the numerous craters to be seen on the moon's surface there are many lines of deep, crooked valleys, known as _rills_, that may at one time have been the beds of rivers. besides the rills, there are many straight clefts about half a mile in width, that extend down into the surface of the moon for unknown depths. these clefts can be seen passing directly through mountains and valleys. they are believed to be cracks or fissures in the moon's surface. on the moon is a great crater called tycho. it is situated near the moon's south pole. the great crater of tycho is by far the most prominent object on the moon's surface. it has a system of rays that extend for great distances around its craters. you will also see if you examine the moon's surface by a powerful glass that there are immense plains called _oceans_ or _seas_. by an appropriate custom the names of the different craters on the moon are the same as the names of the great astronomers and philosophers that have long since passed from their labors, such as tycho, copernicus, kepler, plato, etc. various explanations have been given as to the origin of the craters on the moon's surface, but without going into a discussion it may be said that they are now generally regarded as having been formed in the main just as were the craters of the earth's volcanoes. the tremendous size of the moon's craters is of course due to the great decrease in the force of gravity. this would make the craters, approximately, six times as great as the craters on the earth. professor pickering points out that while the moon's craters resemble more closely those of hawaii than those of any other of the earth's volcanoes, yet there is this difference in them: that while the earth's crater floors are generally considerably higher than the level of the sea, the moon's crater floors are generally below the level of the surrounding country. still, taking them all in all, the craters of the moon's volcanoes resemble those of the island of hawaii, or again quoting from pickering:-- "there seems, indeed, to be no feature found upon the moon which is not presented by these hawaiian volcanoes, there is no feature of the volcanoes that does not also have its counterpart in the moon." chapter xxiii earthquakes an _earthquake_ is a shaking of the earth. it may vary in intensity from a shaking so feeble that it requires the use of a delicate instrument to detect it, to a shaking violent enough to overthrow heavy buildings, and even to make great rents or fissures in the crust. an earthquake then is an _earth-shake_. it may be caused by anything capable of shaking the earth; for example, as the falling of a heavy weight on its surface. now, a shaking so caused is only felt in the immediate neighborhood of the place the weight strikes the earth. on the contrary, in an earthquake, the shaking spreads in all directions through the earth's crust, until, in the case of very violent earthquakes, it reaches portions that may be situated many thousands of miles away from where the shock started. this spreading of the earthquake waves through the solid earth is not unlike the spreading of the circular waves that are set up in a still water surface when a stone is tossed in. any shaking of the earth's crust produces what may be called an earth-shake or earthquake. the mere falling of a raindrop on the earth produces a slight shaking. the falling of a heavy stone produces a stronger shaking, and sets up a series of minute waves, generally called vibrations, that spread around the place in all directions from where the stone struck. these movements, however, while they spread in all directions, just as they do in a surface of a lake, when a stone is thrown into it, are of course much more quickly stopped by the solid earth than similar movements are by the more readily movable water. but, while any shaking of the earth's crust constitutes an earthquake, yet, strictly speaking, an earthquake is produced only by some force that acts suddenly on the earth, _at a point below its surface_, and, therefore, out of sight. this, of course, would rule out all such shakings as are caused by bodies striking the outer surface of the earth. earthquakes may occur in any part of the world, and at any time of the day or year. they do occur, however, most frequently in certain parts of the world, at certain seasons of the year and at certain hours of the day. earthquakes are far from being unusual occurrences. in some parts of the world, such as the island of java, they are very common, and in japan, under certain circumstances, scarcely a day passes without one or more shocks in some part of that little empire. professor mallet, who has made a very extensive study of earthquakes, published in to , in the philosophical transactions, brief abstracts or descriptions of all the more important earthquakes he could find records of during the past , years. the number of earthquakes thus recorded during this period reached , . of this great number nearly one-half occurred during the last fifty years. it should not be inferred from the above figures that the number of earthquakes has really increased so greatly in the past half-century. the explanation of the apparent increase is that greater care has been taken recently in recording earthquakes, and that an apparatus called a _seismometer_, or _earthquake-recorder_, has been invented which automatically produces a record of the smallest shocks; so that a great many have been recorded that would otherwise have passed undetected. it is the opinion of le conte that if the records of all the earthquakes of , years had been thus made there would have been found during the entire time of mallet's researches to have occurred no less than , , while during the last four years of mallet's records, the number would have probably reached two earthquakes per week. since mallet's time, prof. alexis perry published ( ) a much larger list of earthquakes. perry finds that from to there have been , earthquakes, or every year. perry's list, however, is incomplete, since it fails to record earthquakes that occurred in mid-ocean, and in the unexplored and uncivilized parts of the world. so it seems likely that earthquakes are so common that our earth, at some part or other of its surface, is continually shaking or quaking. earthquakes are such tremendous phenomena that they were necessarily observed by the ancients. we find more or less complete accounts of them in various writings. lucretius (titus carus lucretius, a great roman poet) speaks as follows, in his de rerum natura (on the nature of things). we use munro's translation here: "now mark and learn what the law of earthquakes is. and first of all take for granted that the earth below us as well as above is filled in all parts with windy caverns, and bears within its bosom many lakes and many chasms, cliffs and craggy rocks; and you must suppose that many rivers hidden beneath the crust of the earth roll on with violent waves and submerged stones; for the very nature of the case requires it to be throughout like to itself. with such things then attached and placed below, the earth quakes above from the shock of great falling masses, when underneath, time has undermined vast caverns. whole mountains, indeed, fall in, and in an instant from the mighty shock tremblings spread themselves far and wide from that centre. and with good cause, since buildings beside a road tremble throughout, when shaken by a wagon of not such very great weight; and they rock no less, where any sharp pebble on the road jolts up the iron tires of the wheels on both sides. sometimes, too, when an enormous mass of soil through age rolls down from the land into great and extensive pools of water, the earth rocks and sways with the undulation of the water just as a vessel at times cannot rest, until the liquid within has ceased to sway about in unsteady undulations.... "the same great quaking likewise arises from this cause, when on a sudden the wind and some enormous force of air gathering either from without or within the earth have flung themselves into the hollow of the earth and there chafe at first with much uproar among the great caverns and are carried on with a whirling motion, and when their force, afterwards stirred and lashed into fury, bursts abroad and at the same moment cleaves the deep earth and opens up a great yawning chasm. this fell out in syrian sidon and took place at Ægium in the peloponnese, two towns which an outbreak of wind of this sort and the ensuing earthquake threw down. and many walled places besides fell down by great commotions on land and many towns sank down engulfed in the sea together with their burghers. and if they do not break out, still the impetuous fury of the air and the fierce violence of the wind spread over the numerous passages of the earth like a shivering-fit and thereby cause a trembling." of course, no one at the present time believes this ridiculous explanation as to the cause of earthquakes. aristotle, a greek philosopher, speaks thus concerning earthquakes. we quote the translation employed by mallet: "three theories on the subject have been handed down to us by three different persons; namely, anaxagoras of klazomene, before him anaximenes the milesian, and later than these democritus of abdera. "anaxagoras says that the ether of nature rises upward, but that when it falls into hollow places in the lower parts of the earth it moves it (the earth); because the parts above are cemented or closed up by rain, all parts being by nature equally spongy or full of cavities, both those which are above (where we live) and those which are below. of this opinion it may perhaps be unnecessary to say anything, as being foolish, for it is absurd to suppose that things would thus exist above and beneath, and that the parts of bodies which have weight would not on every side be borne to the earth, and those which are light, and fiery, rise; especially since we see the surface of the earth to be convex and spherical, the horizon constantly changing as we change our place, at least as far as we know. and it is also foolish to assert on the one hand that it remains in the air on account of its great size, and on the other to say that it is shaken, when struck from beneath upwards. and besides these objections, it is to be remarked that he has not treated of the attendant circumstances of earthquakes, for neither every time nor place is subject to these convulsions. "but democritus says, that the earth being full of water, and receiving much also by means of rain, is moved by this. for when the water increases in bulk, because the cavities cannot contain it, in its struggles it causes an earthquake. and when the earth becomes partially dried up, the water being drawn from the full reservoirs into those which are empty, in passing from one to the other, by its movements it causes an earthquake also. "anaximenes, however, says that the earth, when parched up and again moistened, cracks, and by the masses thus broken off falling on it, is shaken; wherefore earthquakes occur in drouths and again in times of rain; in drouths, because, as we have said, it cracks, when highly dried, and then, when moistened over again, it cracks and falls to pieces. were this the case, however, the earth ought to appear in many places subsiding. why then is it that hitherto many places have been very subject to these convulsions which do not present any such remarkable differences from others? yet such ought to be the case. and, moreover, those who think thus must assert that earthquakes constantly become less and less, and at last cease altogether. for the continual condensation of the earth would cause this. wherefore, if this be not the fact, it is plain that this is not the correct explanation." besides the above, there are numerous references to earthquakes in the works of other writers. thales, seneca, and pliny all speak of these phenomena and appear to describe correctly the movement of the earth in waves both in the solid land, as well as on the sea. coming down to less ancient writers, mallet refers to a book by fromondi, published in antwerp, in , that contains much valuable and interesting information. among other things fromondi declares that in the year , in the reign of valentinian, there was a great earthquake that shook nearly the entire world and that another earthquake of almost equal severity occurred in . he also states that in an earthquake continued for nearly forty days; that a great earthquake in italy, in , lasted fifteen days, and that another, in spain, lasted for nearly three years. this does not mean that these earthquakes actually continued to shake the earth violently for the times mentioned. these are only the times during which, at intervals of greater or less length, successive shocks were felt in these localities. another of the less ancient writers referred to by mallet is travagini, who published a book in venice in . this book contains a description of a terrible earthquake occurring in italy on the th of april, , which affected large portions of the country adjacent to ragusa. without attempting at present to discuss the various theories of earthquakes, it will suffice to say that earthquakes can be divided, according to their origin, into two classes: _volcanic earthquakes_, or earthquakes that are caused by practically the same forces that cause volcanoes, and _tectonic[ ] earthquakes_, or those produced by the slipping of a large mass of rock lying along the lines of old or new fractures. earthquakes of the first class are found especially in volcanic districts, while those of the second class are found in all parts of the world, whether in volcanic districts or elsewhere. according to dana, earthquakes of the second class generally start in the neighborhood of mountains, where old lines of fractures are especially abundant. as regards the direction of the shaking movements of the earth, earthquakes can be divided into three different classes: _explosive earthquakes_, or those in which the force acts vertically upwards; _horizontal earthquakes_, or those in which the force moves in a more or less horizontal direction, or parallel to the general surface of the earth, and _rotary earthquakes_, or those in which the earth rotates or moves in great eddies or whirls. when the earthquake wave is started below the earth's surface, it spreads through the crust in all directions. the direction these waves will have on emerging, or coming out of the surface, will depend on the distance of this point from the place the waves started. when a place is situated directly over where the wave started, the waves will emerge so as to move vertically upwards, so that the earth at this point will be shaken by an explosive earthquake. as the point where the waves pass out is situated further and further from the place where the waves start, the waves will emerge more nearly horizontally, the greater the distance from the source. in explosive earthquakes, which, as just explained, occur at areas almost immediately above the point where the disturbance starts, the force is, generally speaking, the greatest. in earthquakes of this character the force is sometimes sufficiently great to throw large bodies high up into the air. in the case of the great riobamba earthquake of , the force was not only sufficiently great to fracture the earth in various places, but also to throw bodies lying on the surface great distances into the air. bodies of men were thrown several hundred feet into the air and were afterwards found on the other side of a broad river or high up on the side of a hill. it is possible that humboldt did not inquire with as much care as he should have done into these reports. they were probably greatly exaggerated, since it is difficult to understand how a force great as this would have failed to detach the soil at these places, and hurl it after the people. this much, however, can be accepted, that the upward force was very great. in the great calabria earthquake of march, , dolomieu states that the tops of the granite hills of calabria were distinctly seen to rise and fall. in some cases houses were suddenly raised a great distance in the air, and were afterwards brought down again to a position of rest, at a higher level without any damage occurring to them. in a similar manner during the caracas earthquake of march, , the ground was seen to rise and fall in a nearly vertical direction. but, perhaps, one of the most terrible earthquakes of this character was the earthquake that destroyed the greater part of jamaica in june, . during this earthquake the entire surface of the ground at port royal assumed the appearance of a rolling sea. houses were shifted from their old sites. many of the inhabitants who had succeeded in escaping from the city to the neighboring country were thrown great distances into the air. some of these, by good fortune, fell into the harbor, from which, in some cases, they escaped with their lives. here again the projectile force was probably greatly exaggerated. vertical movements characterized the great earthquake of lisbon, on november st, , the city appearing to have been not far from the point of origin. the commonest type of earthquakes is the horizontal, where the waves emerge at the surface in a direction either horizontal or parallel to the general surface, or at least inclined to it at a very small angle. where the materials of the earth's crust, through which the waves spread, are of the same kind and of the same density in all directions, the area shaken is approximately circular, but where the materials of the crust are more or less dense in some directions than in others, the area of disturbance is of course oblong or elliptical. in some cases earthquakes of the horizontal type are limited almost entirely to a single direction. this is especially the case with earthquakes that occur in mountainous districts. these earthquakes are known as _linear earthquakes_, since they spread almost in a single line. when earthquake waves pass from one medium to another, that is, from one kind of rock to another, the greater portion of the waves is refracted or bent out of their straight direction as they pass into the new medium; a part of the waves, however, are reflected. it is these reflected waves that probably cause rotary earthquakes. the speed with which the surface waves move outwards in all directions, varies not only with the force of the wave, but also with the kind of material through which they pass. this velocity may be in the neighborhood of twenty miles per second, while in others the velocity is as great as miles per second. naturally, one would suppose that the most severe earthquakes are those in which the waves move the most rapidly. on the contrary, however, the comparatively feeble shocks are sent through the earth with greater velocity. in rotary earthquakes, as the name indicates, the ground is whirled or twisted in the manner of a violent eddy, and is often left in this twisted condition. in the great calabria earthquake, huge blocks of stone forming obelisks were twisted on one another in a manner represented in fig. . in this case the pedestals remained unaffected, but the separate blocks of stone were partially turned around, as shown. during this earthquake the earth was so twisted that trees, which had been planted in straight lines before the earthquake, were left standing in zigzags. during the great charleston earthquake, south carolina, the chimney-tops of the houses were separated at places where they joined the roof and were twisted around these places without being overthrown. in some of the houses wardrobes or bureaus were turned at right angles to their former positions, and in some cases were even found with their faces turned towards the wall. [illustration: fig. . heavy stone obelisks twisted by calabrian earthquake of ] mallet suggests that in some cases the rotary motion is more apparent than real, being due only to a to-and-fro motion without any twisting, the apparent turning being due to the greater freedom of motion of the object in one direction than in another. a twisting motion, however, has actually taken place in some earthquakes. while separate shocks, in a given locality, may follow one another at intervals for fairly long times, yet the principal shock or shake that produces the greatest damage is generally of exceedingly short duration. in the caracas earthquake the greatest destruction was accomplished in about one minute. there were three distinct shocks, each of which lasted but three or four seconds. the great calabria earthquake, of , lasted but two minutes. the earthquake of lisbon, in , lasted five minutes, but the first, and worst, shock, was only from five to six seconds. chapter xxiv some of the phenomena of earthquakes the nature of an earthquake and the movements of its waves from their starting place having now been briefly described, it remains to explain some of the strange phenomena that precede, accompany, or follow one. next to the violent shaking of the earth's crust, perhaps the most wonderful and impressive thing is the great variety of sounds and noises. these occur not only while the earth-waves are passing through the crust at any place, but also long before the principal shocks reach the place, as well as long after they have passed. earthquake sounds vary almost infinitely, both in intensity and character. some are like the gentle sighings of the wind, or resemble faint mysterious whisperings; some are not unlike the confused murmurings of a crowded room; some resemble the sounds of a busy street. some sounds are full and strong, like the deep bass notes of a large organ. others resemble the din of a great battle with the reports of the large guns. still others reach the intensity of continuous peals of thunder. but we can better understand the nature of earthquake sounds from an actual description of them in a number of great earthquakes, and by inquiring at the same time into any of the peculiar facts connected. humboldt in his great work, "cosmos," thus describes the varied voice of the earthquake: "it is either rolling or rustling, or clanking, like chains being moved, or like near thunder, or clear and ringing, as if obsidian or some other vitrified masses were struck in subterranean cavities." that the sounds produced during earthquakes are carried through the ground faster than through the air appears clear from the fact that such sounds are sometimes heard in deep mines when they are not at all heard on the earth's surface. in describing the earthquake that occurred in kamtschatka, in , krashenikoff of st. petersburg states that noises were heard like the rushing of a strong underground wind, accompanied by a hissing sound, which resembled the sizzlings heard when red hot coals are thrown in water. in an earthquake that occurred in lincolnshire, england, february th, , a noise was heard closely resembling the sounds of wagons running away on a road. so complete and convincing was the resemblance that several wagoners on one of the roads drew their teams to one side so as to permit the runaway to pass safely. another kind of noise heard during earthquakes is a loud hollow bellowing. sometimes, however, the sounds are more musical in their nature, being not unlike those produced by a very large organ pipe. at other times they resemble the noises produced when steam is blown into cold water. the following account of earthquake sounds is given by daubeny, in his book on volcanoes. it appears that during march, , the people living on the island of melida, opposite ragusa, in dalmatia, were greatly alarmed by sounds that at first they believed due to cannonading either at sea or on the neighboring coast. they afterwards found that these sounds were due to something that was taking place under the ground. the noises continued at intervals until august d, , when a great earthquake occurred, during which one of the highest mountains on the island was cleft or split in one place. the underground noises continued from time to time and so frightened the people that they were about to leave the island permanently and emigrate to the mainland of dalmatia. they were dissuaded from doing so by the government, and while the noises continued at intervals it so happened that no damage came to them. it is said, however, that twenty years after an active volcano broke out on the island. there are various causes that produce earthquake sounds. a very slight rubbing or grinding together of rock surfaces may produce fairly loud noises, the volume of the sound being increased by transmission through the rock masses that lie in the path of the waves. an example of such an increase in the loudness of sounds is seen in the case of several of the large blocks of stone used for some of the piers of kingston harbor, in ireland. when these rocks are moved together by blows of the waves they produce loud and appalling sounds, as if the whole island were being washed away. the same rocks, however, when left high and dry on the falling of the tide, can be caused to rub together, when moved by the hand. under these circumstances, they produce but feeble sounds that can only be heard in their immediate neighborhood. no doubt, some find it difficult to understand how it is possible for comparatively feeble sound-waves to be strengthened by their passage through large masses of solids. this is important and should be made clear. as everyone well knows, the ticking of a watch can only be heard at a short distance when the watch is held in the hand, because the sound-waves cannot readily pass through the body of the person holding the watch to the earth, the materials of the body not being sufficiently elastic. if, however, the watch be placed on the bare surface of a large wooden table from which the tablecloth has been removed, so that the watch can come directly in contact with the wood, and nothing else is placed on the table but the watch, the sound-waves are transmitted to the mass of the table and its entire surface sends them out into the air. the ticking of the watch can then be heard distinctly in almost any part of a large room. mallet states that in nearly all great earthquakes sounds are heard before the principal shock, and in his description of the calabrian earthquake hamilton says: "all agreed that every shock seemed to come with a rumbling noise from the westward, beginning with the horizontal and ending with the vorticose (rotary) motion." according to dolomieu, during the lisbon earthquake, the shocks were preceded "by a loud subterranean noise like thunder, which was renewed for every shock.... this great shock," he says, referring to one of the great upward shocks, "occurred without the prelude of any slight shocks, without any notice whatever as suddenly as the blowing up of a mine.... some, however, pretend that a muffled interior noise was heard almost at the same moment." the noises do not generally continue long after the earthquake shocks. in some cases, however, a very loud noise is heard at intervals for a considerable length of time after the principal shock. this was the case at quito and ibarra, in which a great noise was heard for from eighteen to twenty minutes after the principal shock. in a similar manner during the earthquake of october, , at lima, and callao, south america, peals of underground thunder were heard at truxillo for fifteen minutes after the principal shock. in such cases it seems probable that the noises were not caused by the same impulses that caused the original shock, but by the forces that caused the subsequent shock. humboldt relates that in there were noises heard at guanajuato, from the th to the th of february. they were not, however, followed by an earthquake. humboldt also states that in an earthquake which occurred on the th of april, , on the banks of the orinoco river, in south america, a loud thundering noise was heard, without, however, any shock, but at this time a volcano on the island of st. vincent, in the lesser antilles, although some miles to the northeast, was pouring out streams of lava. again in the great eruption of cotopaxi, in , underground noises were heard as if cannon were being fired. these sounds were distinctly heard at as great a distance as honda on the banks of the magdalena river. now, bearing in mind that the crater of cotopaxi is situated on the high plateau of quito, in a region full of valleys and fissures, it would seem that for the sounds to have been sent through the miles between the mountains and the valley of the magdalena river, the waves must, for the greater part, have been transmitted through the solid earth at some considerable distance below the surface. mallet states that the underground noises which continued for more than a month from the midnight of january th, , at guanajuato, were not followed by any earthquake shocks, that it was if as thunder clouds occupied the space below the surface at that part of the earth and from these clouds there came the slow rolling sounds like short, quick, snaps of thunder. major dutton in his book entitled "earthquakes in the light of the new seismology" gives the following as the principal signs that herald the coming earthquake in the open country. "the first sensation is the sound. it is wholly unlike anything we have ever heard before, unless we have already had a similar experience. it is a strange murmur. some liken it to the sighing of pine-trees in the wind, or to falling rain; others to the distant roar of the surf; others to the far-off rumble of the railway train; others to distant thunder. it grows louder. the earth begins to quiver, then to shake rudely. soon the ground begins to heave. then it is actually seen to be traversed by visible waves somewhat likes waves at sea, but of less height and moving much more swiftly. the sound becomes a roar. it is difficult to stand, and at length it becomes impossible to do so. the victim flings himself to the ground to avoid being dashed to it, or he clings to a convenient sapling, or fence-post, to avoid being overthrown. the trees are seen to sway sometimes through large arcs, and are said, doubtless with exaggeration, to touch the ground with their branches, first on one side, then on the other. as the waves rush past, the ground on the crests opens in cracks which close again in the troughs. as they close, the squeezed-out air blows forth sand and gravel, and sometimes sand and water are spurted high in air. the roar becomes appalling. through its din are heard loud, deep, solemn booms that seem like the voice of the eternal one, speaking out of the depths of the universe. suddenly this storm subsides, the earth comes speedily to rest and all is over." there are many other curious phenomena besides earthquake sounds or noises. among some of the more interesting are the fire and smoke that are seen to come out of fissures that have been rent in the ground. it is possible that in many cases these flashes of fire are in reality produced by electric discharges that momentarily light the clouds of dust thrown up out of the fissure. but sometimes true flames are seen escaping from the fissures. this was the case during the earthquake of lisbon, in , when fire burst through fissures at several places, burning with a lambent flame for some hours. the clouds of dust that follow the rending of mountain masses by earthquakes are probably to be traced to the fracture of the rock masses, the dust so formed being violently thrown forth by the air squeezed out of the fissures, when they are suddenly closed. the violent compression of this air may raise this dust to incandescence. mallet asserts that in many cases the clouds of smoke observed do not consist of true smoke like that produced when wood or vegetable matters are incompletely burned, but is only ordinary air mixed with sulphurous acid gas, and various other gases. but not only fire and smoke are seen at times coming out of fissures in the earth. a thing still more frequently thrown out is water, which often spouts forth along with great quantities of mud, sand, and the finely ground fragments of earthy materials generally. among many other instances where the emission of water from the crevices was particularly noticeable, may be mentioned the earthquakes at jamaica in and . here the water, in some places, was thrown out of the ground to considerable heights in the air. mallet calls attention to the fact that the waters of springs collect in reservoirs consisting either of fissures or crevices of the rocks, of small width but great depth, which are vertical or inclined to the horizon, or in reservoirs that are formed of extended beds of sand or gravel. now, when the earthquake waves moving horizontally over the surface produce movements that squeeze these fissures together, the water in the fissures is spurted out in high jets, and carries with it the finely divided rock or sand formed by the rubbing together of the rock surfaces. in the case of the reservoirs consisting of beds of sand or gravel, lying between impervious layers, if, during an earthquake motion, the land areas are suddenly lowered, the water rushing into the cavity thus left will afterwards be shot out with considerable force, when the land is suddenly raised again. where there are no direct openings in the ground the water will burst through the crust in the shape of great vertical jets, thus forming a circular hole, broken or fractured at its edges. water jets of this character were especially numerous during the earthquake of calabria in . in a swampy plain, known as rosarno, many of these circular wells or openings about the size of an ordinary carriage wheel, though in some cases much larger, were to be seen crowded together. the appearance of the openings are represented in fig. . some of these were filled with water, but the greater number were dry and filled with loose sand. these latter, when examined by digging, were shown to be funnel-shaped, as seen in fig. . as seen, the margins of the wells exhibit a series of cracks or crevices extending radially outward from the centre. their origin is evident. as the water was violently expelled by the squeezing motion of the upper and lower impervious strata, it shot upwards, thus producing the funnel-shaped tube. at the same time the force of the eruption was sufficiently great to produce the radial fissures or fractures at the sides. [illustration: fig. . circular hollow formed by calabrian earthquake] [illustration: fig. . section of circular hollow formed by calabrian earthquake] but greater fissures than these have been formed by earthquakes, especially those of the class created by a slipping of the earth's strata. in the case of an earthquake on the south island of new zealand, in , a fissure having an average width of eighteen inches could be clearly seen extending in a direction parallel to the mountain chain for a distance of sixty miles, and during a later earthquake in the same region, in , a fracture was formed that could be clearly traced for a distance of nearly ninety miles. in some cases these fissures or fractured parts of the crust are left with one of their sides at a higher level than the opposite side. this was the case of the great japanese earthquake of october th, . there are three kinds of waves produced by earthquakes; namely, the earthquake waves proper through the earth; the sound waves in the air, and great forced waves in the sea. the sound waves of course reach the air from the point of origin below the earth's surface through the solid materials of the crust, and take on the curious varieties already described in connection with the sounds accompanying earthquakes. we have already briefly described the manner in which the earthquake waves travel through the materials of the earth's crust. there remain to be discussed the great waves that are rolled up in the ocean during an earthquake shock. these waves are, perhaps, among the most destructive phenomena of great earthquakes. the following are only some of the more remarkable of such waves, and have been taken from mallet's collection of earthquake data. during some of the great earthquakes on the coasts of chile and peru, huge waves from the ocean did great damage when they reached the land. in the earthquake of , ocean waves rushed for several leagues inland over the coast of chile, carrying with them ships that were left high and dry as the wave receded. in the earthquake of , callao was inundated by a great wave from the pacific ocean, and ships were carried a full league into the country. during the earthquake of , callao was again swept away by a huge ocean wave. at later times earthquake waves have caused great damage to several other parts of the coast of south america. ocean waves of this character are formed by successive upward and downward movements at the bottom of the ocean, following each other at very brief intervals. le conte points out that the sudden upheaval of the bed of the ocean forms a huge mound in the surface of the water which results in a large wave that spreads rapidly in all directions. waves produced in this manner sometimes reach a height of fifty to sixty feet. they are not readily observed in the deep ocean, but as soon as they reach the shallow waters near the shore they rush forward, forming waves from fifty to sixty feet in height and, rushing over the land, sweep everything before them. during the great lisbon earthquake of a huge wave started at a point fifty miles off the coast of portugal. half an hour after the earthquake was over several waves, the largest of which was sixty feet in height, rushed over a part of the city and greatly increased the ruin already wrought by the earthquake. according to le conte the great waves so formed moved in all directions across the atlantic ocean. they were thirty feet high when they reached cadiz, eighteen feet in height at madeira, and five feet on the coast of ireland. they even crossed the atlantic, being observed on the coasts of the west indies. a great ocean wave accompanied the japanese earthquake in . as in the case of the lisbon earthquake this wave started in the bed of the ocean off the coast of japan and only reached the island half an hour afterwards. it was thirty feet in height, and completely swept away the town of simoda. owing to water's greater freedom of motion earthquake waves travel greater distances through the water than they do on land. of course, great earthquake shocks as a rule cause a very large loss of life. the following figures from mallet give some idea of the extent of this loss, which is generally a matter of a few moments. in the lisbon earthquake, where the worst shock lasted a few seconds, , people were killed. during other earthquakes the losses have been as follows: , at morocco; , in calabria; , in syria, and probably , in earthquakes that occurred in syria in a. d. and in a. d. . but even these figures give only a meagre idea of the vast loss of life that has occurred during the past. it is said that during the reign of justinian, earthquakes repeatedly shook the whole roman world. the city of constantinople was visited by earthquake shocks that continued at intervals for forty days. deep chasms were opened in the earth and huge masses were thrown into the air. enormous sea-waves were formed. at antioch, during the earthquake of may th, a. d. , , people are believed to have been killed. on the st of july, a. d. , in the second year of valentinian, a dreadful earthquake shook the roman world, and a great wave rolled in from the mediterranean and swept two miles inland, carrying ships over the tops of houses. during this earthquake , people lost their lives at alexandria. in the earthquake of messina in , , people are said to have been killed; and, according to other accounts, , . in the year a. d. , another earthquake at antioch killed , people. during the earthquake of quito, in , humboldt estimates that , natives were either buried in crevices in the earth, under the ruins of buildings, or were drowned in lakes and ponds that were temporarily formed. in this connection mallet writes as follows: "such are the numbers to be met with in narratives, and if we suppose that there occurs one great earthquake in three years over the whole earth and that this involves the entombment of only , human beings, and that such has been the economy of our system for the last , years, we shall have a number representing above , , men thus suddenly swallowed up, with countless bodies of animals of every lower class. sir charles lyell then with good reason suggests that even in our own time we may yet find the remains of men and of their habitations and implements thus buried deep and embalmed, as it were, by earthquakes that occurred in the days of moses and the ptolemies." necessarily the progress of a great earthquake wave will produce great changes in the earth's surface features; for example, landslides, where immense layers of clay or other material slip or slide to a lower level and are thrown across the course of a river, causing its waters to be dammed up and then by spreading to form great lakes. sometimes, after vast bodies of water have been collected in this manner, disastrous floods result later from a sudden giving way of the barrier, and the loss thus caused is occasionally far greater than that directly due to the earthquake. permanent changes of level are frequently caused by earthquakes, as, for example, the coast of chile during the earthquake of november th, , where the coast for many miles was raised from three to four feet above its former plane. in other cases the level of the ground is permanently lowered. this occurred in the bengal earthquake in , when an area of some sixty square miles suddenly sank, leaving only the tops of the higher points above water. in some cases of changes in the level of the ground, large areas being raised in one place and lowered in another, rivers take new courses, and their old courses are completely obliterated. chapter xxv the earthquake of calabria in all students of elementary geography are quick to notice that the extreme southeastern part of italy is shaped something like a boot, which appears to be kicking at the island of sicily. this part of the mediterranean sea has for very many years been the arena or storm centre of more or less intense volcanic activity. to the northwest is the active volcano of vesuvius, as well as the volcanic regions of the phlegræan fields. immediately opposite the point of italy, near the toe of the foot, is the active volcanic mountain, etna, while not far from this point is the volcano of stromboli. in this part of the world was visited by a very severe earthquake. since at that time the country was divided into two parts, known as upper calabria and lower calabria, this earthquake is sometimes spoken of as the earthquake of the calabrias, or more simply as the calabrian earthquake. the great mountain range of the apennines, mainly of granite formation, extends through the central part of italy. the lands adjoining the mountains on each side are flat and marshy, and consequently unhealthy. numerous observers have compiled excellent accounts of the calabrian earthquake. these, having been made by educated persons, are, to a large extent free from the inconsistencies and exaggerations apt to characterize descriptions by ignorant persons, especially when in a condition of excitement or alarm. among reliable writers was sir william hamilton, who made a personal examination of the region, soon after the first severe shock, and collected much valuable information for a paper which was afterwards published in the philosophical transactions of the royal society. then, too, dolomieu, another scientific man of high ability, made a careful study of the effects produced by the earthquake. [illustration: fig. . map of the calabrian earthquake of ] as can be seen by an examination of the map presented in fig. , the part of italy included in the calabrias covers an area from north to south almost equal to two degrees of latitude. although the shock extended beyond the limits of calabria, since it reached as far north as naples, as well as over a great part of the island of sicily, the territory in which the greatest damage was done did not exceed in area about square miles. the southern part of italy is subject to frequent earthquake shocks. pignatari, an italian physician, asserts that this region was visited during by no less than earthquakes, of which were of the first class, or degree of intensity, while in , there were earthquakes, of which ninety-eight were of the first class. it seems that the city of oppido, marked on the above map as midway between the two coasts, was the point from which the severe earthquake of started. if one draws a circle, with a radius of twenty-two miles, around oppido as a centre, the portions of the calabrias that were the most affected will all lie within this circle. the great calabrian earthquake was attended by numerous shocks. the first and the most severe shock, that of february th, , was only two minutes in destroying most of the houses in all cities, towns, and villages on the western side of the apennines in this part of italy. another severe shock occurred on the th of march. this shock was almost as severe as that of february th. in order to understand many of the effects produced by this earthquake, inquiry must be made into the geological character of the region. according to dolomieu, the flat country at the slopes of the apennines, known as the plain of calabria, is covered with sand and clay mixed with sea shells. these strata have been deposited by the sea from materials that have been obtained by the decomposition of the granite mountain ranges in the apennines. the plain is quite level except where it is crossed by deep valleys or ravines, which have been eroded or cut by the swift mountain torrents. in many cases, these ravines or valleys have depths as great as feet. their sides are generally almost perpendicular. consequently, as lyell remarks, throughout the length of the mountain chain, the soil, which adheres but loosely to the granite base of the mountain chain, could therefore be easily separated from the mountain, and sliding over the solid steeps of the mountain could readily move, especially through the ravines or gorges, to distances in some cases as great as from nine to ten miles. this peculiarity of the country must be thoroughly understood, since, otherwise, it would seem impossible that lands could be carried several miles from their former position, and often bear along with them almost undisturbed houses, olive groves, vineyards, and cultivated fields. the heaving of the surface of the earth like the waters of the sea, so common in severe earthquakes, occurred during the calabrian earthquake. in some places this heaving so shook the trees that they bent until their tops touched the ground near their base. parts of the ground were violently thrown upwards into the air as in the explosive type of earthquakes. in many instances the large paving stones were thrown into the air and afterwards found with their lower portions upwards. during the earthquake deep fissures were made in the earth at various localities and there were, moreover, marked changes of level. at messina in sicily the shore was fissured and rent and while before the convulsion the surface had been level, it was afterwards found to be inclined toward the sea. according to dolomieu the following curious incident occurred during the passage of the earthquake waves. a well in the ground of one of the convents of the augustines, lined on the inside with stones, was so affected by the upward thrust given to the land that its stone lining was left projecting above the level of the earth in the form of a small tower some eight or nine feet in height. frequent instances occurred of deep fissures in the surface of the earth. many of these remained open after the earthquake, although in other cases they were firmly closed together before the earthquake shocks ceased. [illustration: fig. . fissures caused by the calabrian earthquake] fig. represents the appearance of certain fissures in a part of calabria during this earthquake. these cracks, it will be noticed, radiate or pass outward in all directions from a central point, just like the cracks that are formed in a glass window pane when it is fractured by a stone thrown against it. of course, the most violent effects were near the origin of the earthquake at oppido. here the formation of deep fissures was common. in another part of the country a number of buildings were suddenly swallowed up in a central chasm, which almost immediately closed, thus permanently burying all these objects. some idea of the force with which the fissures were afterwards closed can be formed by reflecting on a case where, in order to recover some of the buried articles, the ground was dug up at these points, and it was found that the materials, human bodies and other objects, were so jammed together as to make one compact mass. to sir william hamilton a place was shown where the fissures, though, when he saw them, they were not more than a foot in width, had opened sufficiently wide during the shock to swallow up a hundred goats as well as an ox. an earthquake that caused such marked changes in the appearance of the earth's surface, naturally made great changes in the direction of the rivers. in one case the end of a small valley was so completely filled with stones and dirt that the water was dammed up, producing a lake two miles in length and one mile in breadth. in a similar manner no less than lakes were formed in different portions of calabria. of course, in the flat country at the base of the apennines, frequent landslides occurred, the land sliding into great chasms and continuing to move down them for considerable distances, so that in many places pieces of land containing olive trees, vineyards, and green fields, were bodily transported for distances of several miles. this, moreover, was done so quietly as to leave the houses entirely uninjured, and the trees and other vegetation continuing to grow up with apparently no marked decrease in vitality. as is usual in such cases, the sudden and strong blows acting on the waters of the sea, killed great numbers of fish just as does the explosion of dynamite at a point below the surface of the water; and in a similar way the fish that usually live at the bottom of the sea in the soft mud, being disturbed by the earthquake shocks, came near the surface where they were caught in vast numbers. it is an interesting fact that during this earthquake the volcano of stromboli showed a marked decrease in the volume of smoke it gave out. etna, however, was observed to emit large quantities of vapor during the convulsion. lyell tells the following story of the prince of scilla, who with many of his vassals sought safety in their fishing boats. suddenly, on the night of february th, while some of the people were sleeping in the boat, and others were resting on a low plain near the sea, in the neighborhood, another shock occurred, a great mass was torn from a neighboring mountain and hurled with a crash on the plain, and immediately afterwards a wave, twenty feet or more in height, rolled over the level plain, sweeping away the people. it then retreated, but soon rushed back again, bringing with it many of the bodies of the people who had perished. at the same time all the boats were either sunk or dashed against the beach, and the prince with , of his people was destroyed. the total number of deaths caused by this earthquake in the calabrias and sicily were estimated by hamilton at , . besides these about , more perished in epidemics that followed the earthquake, or died for lack of proper food. chapter xxvi the great lisbon earthquake of lisbon, the capital of portugal, on the tagus river, is built along both banks for five miles, and on several small neighboring hills. it is supplied with water by means of an aqueduct, called the alcantara, which brings the water from springs about nine miles to the northwest. for portions of its length the aqueduct is placed underground, but where it crosses the deep valley of the alcantara it is supported, for a distance of , feet, by a number of marble arches, which in one place are feet in height. this fact is put forward not merely for the sake of its artistic interest, but because, strange to relate, this part of the aqueduct remained uninjured during that great earthquake, the greatest of modern times. on the st of november, , this frightful catastrophe, according to lyell, from whose excellent account much of the information contained in this chapter has been obtained, struck the beautiful city almost without any warning. terrible sounds came suddenly from underground; almost instantly afterward a violent shock threw down the greater portion of the city; in less than six minutes , people were killed. the place from which this earthquake started must have been situated on the bed of the ocean at some distance from the coast; for the great wave thus raised in the atlantic ocean did not reach the mouth of the tagus river until about half an hour after the most severe shocks were over. the arrival of this wave at the mouth of the tagus was announced by the sea retiring to such an extent as to leave the bar dry. then a huge wave, sixty feet in height, rolled in from the ocean and completed the work of destruction that had been commenced by the earthquake. so great was the shock that the mountains in the neighborhood were violently shaken and some of them split or fractured in a most wonderful manner. particularly large was the loss of life in the churches whither hundreds hastened for refuge when the shakings of the earth began, for most of these buildings fell and buried the worshippers. another immense loss of life was caused by the destruction of a large marble quay or wharf that was suddenly swallowed up by the sea. while the buildings in the city were being overthrown by the violent shakings of the earth, a multitude sought the quay as a flat place where they could not be injured by the falling buildings. suddenly, however, this structure sank into the water and not only were all the people drowned, but none of the bodies was ever afterwards found. failure to find any remnants of the pier or any of the people who perished on it has been attributed to the formation of eddies or whirls that were sufficiently strong to carry down vessels by suction similar to that of the famous maelstrom off the coast of norway. of course, in a time of boundless excitement like that of the lisbon earthquake, accounts are apt to be highly exaggerated. for example, assertions are made in many books that the water left in the harbor after the sinking of the quay was unfathomable. now, in point of fact, the depth of this place has been measured and found to be less than fathoms. when it is remembered that not one of the bodies of the people on that quay was ever again seen, it is possible, as lyell suggests, that a deep fissure or chasm opened immediately on the ground on which the quay stood, so that it, together with all on it, were dropped into the chasm, which, closing, buried them deep in the earth. the lisbon earthquake was especially noted for the extent of country affected by it. humboldt estimated this area as being more than four times the size of europe. in parts of this area immense mountain ranges, such as the pyrenees, alps, etc., were violently shaken. when the size of these mountains is considered one realizes that it must have required a mighty force to shake them. these shakings were so severe that they produced a deep fissure in the ground in france. continuing towards the north the solid earth was shaken as far as the shores of the baltic and norway and sweden, generally. this, of course, included the flat country of northern germany. the hot springs of toplitz disappeared for a time, but, breaking out afterwards, discharged such quantities of muddy water that the surrounding country was inundated. the waves crossed the atlantic, causing high tides on the island of antigua, barbadoes, and martinique, of the lesser antilles, where, instead of the usual tides of two feet, tides of twenty feet high were observed. further to the north the waves reached the eastern shores of north america, and shook the continent as far west as the great lakes, and spread in the north atlantic as far as iceland. toward the south the waves affected parts of northwestern africa, where much loss of life occurred in the villages some eight leagues distant from the city of morocco. here from , to , people were killed, being swallowed up by deep fissures in the earth, which afterwards closed on their bodies. severe shocks were in many cases felt on vessels at sea. in one instance, although the vessels were at considerable distances from where the waves started, the captains reported that the shocks were so great that on several occasions it was believed the vessel had struck a rock, till, on heaving the lead, they found that they were in very deep water. in another instance, such was the shock to the vessel that the planks on the deck had their seams opened. in still another case several of the sailors were thrown into the air for a distance of about one and a half feet. it has been frequently observed that when great earthquakes happen, curious changes take place in the level of the waters of lakes entirely disconnected with the ocean; for example, mountain lakes, far above the level of the sea, the water suddenly rising and then resuming its original level. sometimes the waters of such lakes have suddenly disappeared, probably being drained off through a fissure formed in the bed of the lake. in such event the lake generally remains dry after the passage of the earthquake. at the time of the lisbon earthquake it was observed that the water of loch lomond in scotland first rose above its ordinary, then sank again to its usual level. this difference of level is explained by lyell as follows: when the earthquake waves reached the lake, the water being unable to take the sudden shove given to it by the earthquake waves, dashed over that side of the basin which first received the shock. assuming this to be the case, since the rise of the level in the water of loch lomond was two feet and four inches, it is comparatively easy to calculate the speed of movement that the earthquake waves had, when they reached this body of water. calculated in this way it would seem that the waves had a speed of about twenty miles a minute. but what especially characterized the lisbon earthquake were the great waves that were produced in the ocean. besides the huge wave that entered the tagus, a wave of the same height swept eastward along the southern coast of spain, and the northwestern coast of africa. at tangier in africa it swept the coast as a very high wave no less than eighteen times, or, in other words, eighteen huge waves rolled in from the ocean. at funchal, on the madeira islands, this wave rose fifteen feet above the high water mark. many attempts have been made to explain the manner in which the great sea waves are started in earthquake movements. some believe that they are due to the sudden raising or heaving up of the water, far above ordinary level. but, as lyell points out, this explanation would not be satisfactory for the waves produced in the case of the lisbon earthquake, since it would fail to account for the fact that both on the coasts of portugal as well as on the island of madeira the high wave was preceded by a movement of the water toward the point of origin; that is, the waters moved away from lisbon and the madeira islands, so as to leave the water very low at those points, when shortly afterwards a huge wave rushed in from the sea and swept over the land. earthquake waves move much more rapidly through the solid rocks of the earth's crust than through the waters of the ocean. the shock transmitted through the solid earth from lisbon to the madeira islands took only twenty-five minutes to reach the islands, while the waves in the ocean took about two and a half hours to cover the same distance. chapter xxvii the earthquake of cutch, india, in cutch is one of the provinces of india lying on the western coast of hindostan, east of the delta of the indus river. a great earthquake occurred in this region on june th, . as indicated by the map presented in fig. , by lyell, the district of cutch lies on the coast of the arabian sea. cutch is at times a peninsula, being washed on the south and east by the arabian sea and the gulf of cutch, and on the north by a depression known as the runn of cutch which, during unusual tides, is overflowed by the waters of the sea, but for the rest of the year is dry. the earthquake of cutch was apparently central at the town of bhooj, where the destruction was extreme, hardly a house being left standing. the shock extended over a radius of about , miles from bhooj, reaching to khatmandoo, calcutta, and pondicherry. at anjar the fort, together with its tower and guns, were completely ruined. the shocks continued at intervals after the principal shock until june th, when the volcano of denodur is said by some to have emitted flames, although this is denied by others. great changes were produced in the eastern channel of the indus, which forms the western boundary of the province of cutch. the water in this inlet had become so low that it was readily fordable at low tide at luckput, and was only covered with six feet of water at high tide. after the earthquake it deepened at the port of luckput to over eighteen feet at low tide, while in other parts of the channel the water had deepened from four to ten feet at high tide, where before the earthquake shock it had never been deeper than from one to two feet. indeed, after these changes the inland navigation of the country again became possible after having been closed for many centuries. [illustration: fig. . map showing district visited by the earthquake of cutch of ] the cutch earthquake resulted in a marked depression of the country, especially north of luckput, where the fort and village of sindree were so quietly sunk that the fort, with its tower and walls, was left projecting slightly above a body of water that not only completely covered the old site but also formed a large lake marked on the preceding map, at sindree, by the dark shading. it was this change of level that deepened the eastern channel of the indus, just mentioned. [illustration: fig .. sindree before the earthquake of ] fig. , from lyell, gives an idea of the appearance of the fort at sindree before the earthquake. the appearance of the fort after its submergence is represented in fig. , where, as will be noticed, only the top of the tower and the walls remain above the surface of the water. that the masonry was not affected either by the earthquake, or by the inrush of waters, is evident from the fact that the ruins were still standing in march, , as represented in the figure. in heavy shading on the map in fig. is a large area lying in the northern part of the province known as the runn of cutch. this is a flat region of about , square miles. it owes its level surface to its being the deserted or dried-up bed of a sea. for the greater part of the year its bottom is dry and hard, and is covered with a crust of salt half an inch or so in thickness. [illustration: fig. . sindree after the earthquake of ] according to lyell, from whom most of the facts concerning this earthquake have been obtained, the runn of cutch is connected with a vast inland sea, not only by the water driven into it through the gulf of cutch, but also through the eastern channel of the indus at luckput. these changes occur especially during the monsoon, when the seas are high, and especially after the heavy rains that come with these winds, when the wet condition of the soil permits the sea water to spread rapidly. traditions of the natives tend to confirm belief that cutch a long time ago was a true peninsula, and that the runn of cutch was then an arm of the sea. that a change of this character did occur in the runn of cutch seems to be proved by the ruins of old towns now far inland that are said to have been ancient seaports, and as apparent evidences of this many pieces of wrought iron and ships' nails have been found in parts of the runn. at the same time that the sinking of the land around the fort and village of sindree took place a considerable elevation occurred in the neighborhood. immediately after the earthquake, the people in sindree saw that a low hill or mound had been thrown up in a place that before had been a low and perfectly level plain. they named this elevation the ullah bund, or _the mound of god_, in order to distinguish it from several embankments that had been built directly across the eastern mouth of the indus; for the ullah bund had been raised by the earthquake across the same branch of the indus. for several years after the earthquake of marked changes kept developing in the channels of the indus. during a large body of water entered into the eastern branch of the indus above the ullah bund and finally forced its way through the mound, thus establishing a direct course to the sea. the ullah bund, being thus cut in two, an opportunity was afforded of seeing the materials of which it was composed. these were found to consist principally of clay filled with shells. the opening of the river resulted in throwing such large quantities of fresh water into lake sindree that its waters were rendered fresh for several months, but at last regained their saltiness. dana states that in another earthquake occurred in this district which converted sindree lake into a salt marsh. chapter xxviii the san francisco earthquake of april , about twelve minutes past five o'clock on the morning of the th of april, , the inhabitants of san francisco were rudely awakened by a few frightful earthquake shocks. their houses were violently shaken to and fro, and on all sides were heard the awful crashings of falling walls, chimneys, and buildings, together with the death-shrieks of those caught in the ruins. rushing madly into the streets they could see on every side evidences of destruction; for, in almost every direction, were heaps of fallen buildings, still being violently shaken by the earthquake waves that rapidly passed through the solid earth. huge cracks or crevices had been formed in the streets, while the heavy rails of the trolley tracks had been bent and twisted by the mighty forces. before describing in detail the great san francisco earthquake, the location of the city and its surroundings demand consideration. as can be seen from the map, fig. , san francisco is situated on the western coast of california, at the northern end of a peninsula, some twenty miles in length and about six miles in width. this peninsula is formed by the magnificent bay of san francisco on the east, a navigable strait called the golden gate on the north, and the pacific ocean on the west. [illustration: fig. . map of western coast of california showing position of san francisco] san francisco bay, accessible by the golden gate, is the principal harbor on the pacific coast, and is, indeed, one of the most magnificent harbors in the world. it is land-locked, that is, surrounded by a continuous land border except at its entrance through the golden gate. including san pablo bay, it has a length of about fifty-five miles, and varies in breadth from three to twelve miles. the entrance to the harbor, however, is impeded by a bar across the mouth of the golden gate, over which there is a depth of but thirty feet of water at low tide. san francisco has over miles of streets, miles of which are paved. the city is lighted by both electricity and gas, and has an extensive system of water-works, the water being brought from the pilarcitos and calaveras creeks, situated from twenty to forty miles respectively from the city. san francisco is in a region where earthquakes are common. it might, therefore, be visited at any time by a great catastrophe. there have occurred between and , no less than earthquake shocks in the state of california, these shocks having been especially frequent in the country surrounding san francisco bay. the most severe were the earthquake of , which injured san francisco; the owens valley earthquake of ; the vacaville earthquake of ; the mare island earthquake of ; and a smaller earthquake in . since there was a period of rest until the th of april, . as in the case of practically all severe earthquakes, that which destroyed san francisco consisted of a few momentary shocks: then all was over. according to a preliminary report of the state earthquake commission, appointed by the governor of california, april st, , these shocks, as recorded in the observatory at berkeley, began at twelve minutes and six seconds after five a. m., pacific standard time. their entire duration was only one minute and fifty seconds, but, as frequently happens, there were a number of minor shocks, following at regular intervals during the next few hours as well as the next few days. while the most severe shocks were in the neighborhood of the peninsula of san francisco, yet minor disturbances were felt as far north as coos bay, oregon, and as far south as los angeles, california. as shown by recording instruments at the seismograph station at washington, d. c., sitka, alaska; potsdam, germany; and tokio, japan, a series of waves were propagated through the earth, as well as over its periphery. the damage done within the city limits was wide-reaching. among the buildings almost completely destroyed were the city hall, on which about $ , , had been expended, the united states post office, besides many business blocks, hotels, department stores, theatres, banks, churches, and dwelling houses. amid the terrors of such a calamity it is difficult to obtain observations possessing any scientific value. fortunately, however, there was in the city a physicist trained to observe phenomena of this character, professor george davidson of the university of california. like others, he had been awakened by the first severe shock. at once recognizing the nature of the phenomenon, and desirous of obtaining the exact time of its occurrence, he counted seconds while he ran towards the table on which he had placed his watch, and in this way estimated that the shock occurred at twelve minutes past five in the morning. the closeness of this observation is emphasized by the fact that it differed from the recorded time by only six seconds. he states that the motion, at the time of its greatest intensity, closely resembled that of a rat vigorously shaken by a terrier. the destruction caused by the earthquake was, however, but a small part of the total loss to the city. fires were almost immediately started in the ruined houses by the fires in the kitchens and other parts of the houses, by the ignited jets of the illuminating gas, and, perhaps, especially, by the crossing of numerous electric light wires. the manner in which the woodwork and other combustible materials of the buildings were loosely tossed together by the shocks helped the quick spread of the fires, and this, too, was probably greatly aided by the illuminating gas from the broken gas pipes and mains. eight severe conflagrations were, therefore, soon raging in different parts of the doomed city. what made these fires especially dangerous was the fact that the earthquake shocks had destroyed the water pipes. thus the firemen were handicapped in their heroic endeavors to extinguish the flames. at the time of the fire a strong wind was blowing from the northeast. since the firemen were unable to check the flames, the fire line rapidly advanced. its path led towards the best residential parts of the city through portions of the mission section containing a dense population of poor people. the dwellings in this latter section consisted of frame houses, through which the flames rapidly spread. there was but one way to save the city from total destruction--a free use of dynamite! this was intelligently employed until the supply gave out, when it seemed that the city was doomed to utter destruction. but at the last moment, as it were, came a lucky change in the direction of the wind. instead of blowing from the northeast, the steady southwest winds set in, and beat back the fire on itself, so by friday, the th being wednesday, it was under complete control and the rest of the city was saved. [illustration: a san francisco pavement torn by the earthquake _from a stereograph, copyright, , by underwood & underwood_] the extent of the fire is thus described in an article in the "outlook," for saturday, april th, , as follows: "the turn in the direction of the fire endangered for a time the great ferry house, at the foot of market street. while the section actually destroyed is not, geographically speaking, much more than one-third of the city limits, yet it is in the heart of san francisco, and includes the chief business streets and the mission district, inhabited by poor people, and a large part of the so-called nob hill quarter, where were the finest and costliest residences of the city. another fine residence section, civic heights, escaped, together with that known as the western district. "the unburned district, though large in extent, was in the nature of suburbs, and was not closely built up, so that estimates made, as late as saturday, declared that three-fourths of san francisco's improvements in real estate had been destroyed." the burnt district was about two miles from east to west and from two to four miles from north to south, with, of course, very irregular outlines. naturally, the great destruction wrought by the earthquake of april th, , attracted the almost universal attention of scientific men especially interested in earthquake phenomena. we are, therefore, able to speak authoritatively about the probable causes. the great san francisco earthquake of april th, , appears to have been a _tectonic_ quake. ransome, in an article entitled, "the probable cause of the san francisco earthquake," says: "the region thus amply fulfils the conditions under which tectonic earthquakes arise. it is in unstable equilibrium, and it is cut by long northwest faults into narrow blocks which are in turn traversed by many minor dislocations. under the operation of the unknown forces of elevation and subsidence, stresses are set up which finally overcome the adhesion of the opposing walls of one or more of the fault fissures; an abrupt slip of a few inches, or a few feet, takes place and an earthquake results. the region extending for some hundreds of miles north and south of the bay of san francisco may be considered as particularly susceptible to shocks on account of the number and magnitude of the faults and the evidences that these furnish of very recent slippings and the marked subsidence in the vicinity of the golden gate." chapter xxix some other notable earthquakes it would, of course, be impossible within the limits of this book to attempt a description of all the remarkable earthquakes in the annals of science; but before leaving this part of the theme a brief account of a few more among the many may be worth while. jamaica, one of the west indian islands, about ninety miles south of cuba, suffered a very destructive earthquake in . during this earthquake the ground was agitated like the waves of the sea. these movements were so violent that numerous fissures were made in the ground, as many as being formed at the same time, rapidly opening and closing. many of the inhabitants were swallowed up in these fissures. in some cases, however, their bodies were afterward thrown out of the fissures, along with quantities of water. the jamaican earthquake was characterized by marked sinkings of the ground. at the city of port royal, which was then the capital, many houses on the harbor side sank in from twenty-four to forty-eight feet of water. as in the case of the earthquake at cutch, many of these houses were left standing, the chimney tops of some being seen above the water, with their foundations and other parts apparently uninjured, and some of them were standing at a date as late as . at a little later date, , they were mostly ruins. during the jamaican quake a tract of land containing at least , acres near the town was sunk, and a wave of the sea rolled over it. this wave is said by lyell to have carried a frigate over the roofs of the houses and left it stranded on one roof. when the wave rolled back to the sea, the weight of the frigate made it fall through the roof. perhaps one of the most remarkable things about the jamaican earthquake was the swallowing up of several plantations, which disappeared, together with all their inhabitants, their former place becoming a lake. but the lake soon disappeared, leaving a mass of sand and gravel which obliterated any least sign that dwellings and trees had once adorned the spot. the forces developed during this earthquake were sufficiently powerful to make several rents in the blue mountains, and the shock of blows on the waters of the sea killed fish by the hundred thousands so that the silver shine of their dead bodies stretched for miles and was beheld for days "on the face of the deep." portions of the world that have been frequently visited by mighty earthquakes, are the coasts of chile. on the th of may, , a part of the chilian coast near the ancient town of concepcion, sometimes called penco, was destroyed by an earthquake, and the powerful earthquake waves that afterwards rushed in from the sea. so complete was this destruction that the ancient harbor was rendered useless and the people had to build another town about ten miles from the coast, so as to be beyond the reach of earthquake waves from the sea. another great earthquake occurred on the coast of chile on the th of november, . this shock was felt simultaneously over a distance of , miles from north to south. it reached its greatest intensity about miles north of valparaiso. this earthquake caused a rising of the coast to a height of from three to five feet. from careful examinations it appears that the area over which a permanent elevation of the country took place must have been equal to , square miles, an area equal to about half of the area of france, and five-sixths that of great britain and ireland. "if we suppose," says dana, "the elevation to have been only three feet on an average, it will be seen that the mass of rock added to the continent of america by the movement, or, in other words, the mass previously below the level of the sea, and after the shock, permanently above it, must have contained fifty-seven cubic miles in bulk; which would be sufficient to form a conical mountain two miles high (or about as high as etna) with a circumference at the base of nearly thirty-three miles.... assuming the great pyramid of egypt, if solid, to weigh in accordance with the estimate before given , , tons, we may state that the rock added to the continent by the chilian earthquake would have equalled more than , pyramids. "but it must always be borne in mind that the weight of rock here alluded to constituted but an insignificant part of the whole amount which the volcanic forces had to overcome. the thickness of rock between the surface of chile and the subterranean foci of volcanic action may be many miles or leagues deep. say that the thickness was only two miles, even then the mass which changed place and rose three feet, being , cubic miles in volume, must have exceeded in weight , , pyramids." the shocks of this earthquake continued from the time of its occurrence, on november th, , to the end of september, , and even then there were scarcely two days that passed without a shock. on the th of february, , the same part of the world was in the throes of an earthquake that was felt nearly , miles from north to south, or from near the town of concepcion to the isle of chiloe, and from east to west a distance of about miles, from mendoza to the island of juan fernandez, which you probably know better as robinson crusoe's island. by this earthquake the new town of concepcion and several other towns were partly destroyed. there were the same phenomena connected with great sea waves that are common in earthquakes of this character. both this and the preceding earthquakes probably began on the bed of the ocean at some distance from the coast; for, in the last earthquake, the sea retired from the bay of concepcion and vessels were grounded that had been anchored in seven fathoms of water. shortly afterwards waves from sixteen to twenty feet in height rushed in from the ocean and swept over the land. it is interesting in this connection to note that the volcanoes of the chilian andes were in an unusual state of activity before, during, and after the earthquake. another characteristic of this quake was the great number of severe shocks. between the day of the first great shock; i. e., on february th, , and march th, there were more than severe shocks. in this as in the preceding quake a notable elevation of the land near the coast occurred, amounting to from four to five feet, and a part of the bed of the ocean near the coast was raised permanently above the level of the sea. in the description of the explosive eruption of krakatoa in , the fact was noted that the island of java is very frequently visited by earthquakes. here a terribly severe earthquake occurred on the th of january, . there were no less than shocks of great intensity. considerable property in the city of batavia was destroyed, and a neighboring river, that has its head waters by a volcano near the city, ran high and muddy and brought down multitudes of fishes that had been killed, together with many buffaloes, tigers, rhinoceroses, deer, and other wild beasts. seven hills bordering on the river sank down, damming up the streams of the region and thereby causing wide destruction from floods. during portions of the years and an earthquake occurred in the united states, in the mississippi valley near the town of new madrid, missouri, at the mouth of the ohio river. these shocks continued almost incessantly for several months, and were accompanied by a sinking of the ground over large areas. this depressed area, known in the neighborhood as _the sunk country_, extended along the course of the white water river and its tributaries for a distance of about eighty miles from north to south, and several miles from east to west. most of it was converted into a marshy lake characterized by thousands of submerged trees. the area was covered for the greater part with water to a depth of about three to four feet. as the earthquake shocks continued at intervals for several months there was an ample opportunity for studying the peculiarities of the earth waves. the ground rose and fell like large waves in the sea, and after the crest of the waves had reached great heights, the ground burst, and threw large quantities of water, sand, and earth into the air. [illustration: fig. . new zealand] throughout the disturbed district there were numerous depressions known as _sink-holes_, or irregularly shaped pits, varying from ten to thirty yards across, and having a depth of about twenty feet. these were formed by the forcible ejection of large quantities of water mixed with sand. new zealand has been subject to earthquake shocks for a long time, the years , , , , and being especially marked by such visitations. it is a characteristic of the new zealand earthquakes that they have produced a marked change in the coast line. this was particularly the case with those of and . the d of january, , an earthquake occurred that was most violent in the narrowest part of cook's strait, a body of water separating the two principal islands that constitute new zealand; or, as they are called, the north island and the south island. these shocks were felt at sea by ships miles from the coast. the entire area shaken, including the water, has been estimated at three times the area of the british isles. in the vicinity of the southern shores of the north island a tract of land having an area of , square miles is believed to have been permanently raised from one to nine feet. the earthquakes in new zealand are evidently of the tectonic type. during that of a rent or fissure was formed, which, though but eighteen inches in average width, yet extended for a distance of sixty miles in a direction parallel to one of the mountain chains. on the st of august, , an earthquake of considerable intensity occurred in the united states in the neighborhood of the city of charleston, south carolina. the details of this earthquake were carefully studied by major dutton of the u. s. a., and published in the ninth annual report of the united states geological survey of . charleston is situated on a narrow tongue of land between the ashley and the cooper rivers, about seven miles from the atlantic ocean. there are in this area numerous creeks connected with the drainage of these rivers. as the city limits extended, the creeks were filled in, forming "made land," all buildings or structures erected on this land being supported by pilings. it appears that the point at which the earthquakes started was situated sixteen or seventeen miles from charleston. the earthquake shock affected a large area of the united states. fig. shows curved lines called isoseismal connecting places, having the same degree of seismic intensity. this map shows that these isoseimals are marked by figures or numbers from two to ten. these numbers are the numbers of the rossi-forel earthquake scale. they indicate varying degrees of intensity, beginning from the least intense shock which is marked as two and ending with the severest shock marked as ten. there is one degree not marked on this map, the least, called the micro-seismic shock. the shocks then increase in intensity as follows: ii. extremely feeble shocks; iii. very feeble shocks; iv. feeble shocks; v. shocks of moderate intensity; vi. fairly strong shocks; vii. strong shocks; viii. very strong shocks; ix. extremely strong shocks; x. shocks of extreme intensity. the meaning of the map presented in the accompanying figure will now become more apparent in several ways. that portion numbered ten, denoting where shocks of greatest intensity have been experienced, clearly indicates the region just above the point where the earthquake originated. beyond this is a region marked nine where the earthquake shock has decreased in intensity to the next figure on the rossi-forel scale, and then to eight and a half, seven, six, five, four, three, and two. [illustration: fig. . map showing region affected by the charleston earthquake of ] the charleston earthquake damaged property to a considerable extent; for, although comparatively few buildings were completely destroyed, a considerable number were partially injured, and many, not thrown down by the shock, had to be torn down in order to insure public safety. the loss of life, fortunately, was comparatively small. during this earthquake a number of openings called _craterlets_ were made in the ground by the forcible ejection of large quantities of water and sand. the empire of japan is another part of the world particularly subject to great as well as frequent earthquake shocks. although japan is also especially noted for its volcanic activity, its earthquakes are almost entirely of the tectonic type, or are due to the slipping of the land at faults in the earth's crust. most of these quakes occur on the bed of the ocean on the sides of a steep slope that extends down to a very deep part of the pacific known as the _tuscarora deep_. on the th of october, , japan was visited by a great quake, generally known as the mino-owaro earthquake, from the name of the two provinces of mino and owaro in which it occurred. this earthquake is correctly regarded as one of the most severe in japanese records. originating, as it did, in a densely populated section, it caused a great loss of life and property. the deaths reached about , , while the number of houses entirely destroyed reached about , and those partly destroyed nearly , . the total area markedly affected reached , square kilometres, while the area sensibly affected reached , square kilometres, or a little more than one-half the empire. the place at which this earthquake started was situated, not as usual on the bed of the ocean, but on the surface of the land. the first shock was the strongest and wrought the greatest havoc. besides the loss of life and property, the damage to the system of dikes or levees on the river where it passed through the delta plain near the river's mouth was heavy, and singular in some of its features. in one case, near the city of nagoya, on the bay near the southern coast of niphon, one of these levees was lifted and shifted bodily more than sixty feet from its original position. that this quake was of the tectonic type was evident from the great fault that was formed. according to davison this fault was seventy miles in length and in places had a breadth of from two to five feet. it extended from east to west, crossing the entire width of the island. another great earthquake was that which hit northeastern bengal and assam in india on the th of june, . according to the india geological survey, by whom a careful examination of the effects produced by this quake was made, it was, perhaps, the greatest quake that ever happened, not even excepting the lisbon earthquake. the place where the quake started appears to have been of unusual size and irregularity of outline. its southern boundary was almost in the shape of a straight line extending from east to west about miles, and covering a total area of nearly , square miles. over all this vast area the intensity of the shock was exceedingly severe. the total area perceptibly shaken by the quake was about equal to , , square miles. that this quake was of the tectonic type became evident, when several faults were found in the ground afterwards. some of these extended twelve miles, with a breadth at places as great as thirty feet. valparaiso, or, as the name means, vale of paradise, the second largest city of chile and its chief seaport, lies about ninety miles east of santiago, the capital, with which it is connected by a railroad. this beautiful sea city is built at the base of a cluster of hills about , feet above sea level. on august th, , it was visited by an earthquake. there were two distinct shocks. contrary to general rule it was not the first, but the second shock that did the most damage, coming about ten minutes after the first. as you will see from the above date the earthquake of valparaiso occurred shortly after the catastrophe of san francisco. in a general way, its coming was predicted by dr. g. f. becker of the united states geological survey, on april th, , one day after the san francisco disaster. becker published an article in the "new york tribune," in which he argued that the severe shock at san francisco, having occurred on one part of the earthquake region extending around the pacific, would probably soon affect other portions of this region along the pacific coast line of this hemisphere. as at san francisco fierce fires immediately started in the ruins of the houses, but the valparaisans were more fortunate in having a water supply available. there were very many shocks following the first two of this earthquake. indeed, during august th, th, th, and th, no less than were noted. santiago, situated at the foot of the andes, was also considerably damaged by the same earthquake. estimates, probably conservative, put the total of dead in both cities at , and the number of people rendered homeless temporarily, at , . chapter xxx sodom and gomorrah and the cities of the plain the eastern border of the mediterranean sea or syria, with that part of arabia forming the sinai peninsula and which lies between the two northern arms of the red sea, is a region formerly characterized by extreme volcanic activity. this region includes the greater part of the land promised, according to the old testament, to the children of israel. through a large part of this region flows that historic river, the jordan, until it empties into the dead sea, also called the salt sea, the sea of the plain, and by some lake asphaltites because of asphalt or bitumen so abundant on its shores. this river has its source in the mountains of lebanon, some distance north of the sea of chinnerth, tiberius, or the sea of galilee, which empties into the river jordan. as the map in fig. shows, this famous, though small river, flows between ranges of high hills, or low mountains, that lie on both its eastern and western boundaries; and these parallel ranges extend down to the gulf of akaba, which forms the eastern boundary of the sinai peninsula. the sea of galilee, the valley of the jordan and the country between the dead sea and the gulf of akaba, are all, for the most part, considerably below the level of the mediterranean or the red sea; the sea of galilee being about feet and the dead sea feet below that line. [illustration: fig. . syria] that this country has been the scene of great volcanic activities is evident from the volcanic rocks found over different portions of its surface. moreover, the remains of several craters are still visible. on the western banks of the jordan numerous dikes and streaks of basalt occur in the limestone that covers parts of the region. besides there are thermal springs whose waters are at a temperature, according to daubeny, of ° f. then, too, in the neighborhood of the dead sea, as well as in the neighborhood of the adjoining mountain ranges, there are quantities of sulphur and asphaltum or bitumen, while on the dead sea asphaltum is found floating in sufficient quantity to be a source of considerable revenue to the boatmen who collect it. it was in this region that sodom, gomorrah, and other cities of the plain were situated; cities so wicked that god utterly destroyed them by volcanoes and earthquakes. volcanic activity was evidently common in this land of the bible during the times of the prophets of israel; for in their poetic writings are frequent references to such phenomena--beautiful and majestic similes and metaphors derived from contemplation of live volcanoes. jeremiah says: "behold, i am against thee, o devouring mountain, saith the lord, which destroyeth all the earth; and i will stretch out mine hand upon thee, and roll thee down from the rocks, and will make thee a burnt[ ] mountain. "and they shall not take of thee a stone for a corner, nor a stone for foundations; but thou shalt be desolate forever, saith the lord." (jer. li, - .) so, too, the prophet isaiah says: "oh that thou wouldst rend the heavens, that thou wouldst come down, that the mountains might flow down at thy presence! "as when the melting fire burneth, the fire causeth the water to boil, to make thy name known to thine adversaries, that the nations may tremble at thy presence! "when thou didst terrible things which we look not for, thou cameth down, the mountains flowed down at thy presence." (is. lxiv, - .) so, too, the prophet nahum says: "the mountains quake at him, and the hills melt, and the earth is burned at his presence, yea, the world, and all that dwell therein. "who can stand before his indignation? and who can abide in the fierceness of his anger? his fury is poured down like fire, and the rocks are thrown down by him." (nahum, i, - .) let us now examine briefly the description moses gives of the destruction of sodom, gomorrah, and other cities of the plain. this destruction occurred during the life time of abraham and his nephew lot. the record says that god told abraham he intended to destroy them because of their wickedness. then follows in the th chapter of genesis the eloquent pleading of abraham for one of the doomed cities. at abraham's earnest plea god promises to spare sodom if fifty righteous men can be found therein. obtaining this respite, abraham repeatedly asks further mercy for the city, and at last receives the sacred promise that the city shall not be destroyed, if but ten righteous people can be found there. an evidence of the great wickedness of the city is seen in the fact that not even ten could be found. whereupon the lord gives notice to lot that the cities were doomed and commands lot to leave at once with his family. "escape for thy life; look not behind thee, neither stay thou in all the plain; escape to the mountain, lest thou be consumed!" moses describes what happened as follows: "the sun was risen upon the earth, when lot entered into zoar. "then the lord rained upon sodom and upon gomorrah brimstone and fire from the lord out of heaven; "and he overthrew those cities and all the plain, and all the inhabitants of the cities, and that which grew upon the ground. "but his wife looked back from behind him, and she became a pillar of salt. "and abraham gat up early in the morning to the place where he stood before the lord: "and he looked toward sodom and gomorrah, and toward all the land of the plain, and beheld, and lo, the smoke of the country went up as the smoke of a furnace." (gen. xix, - ). this is clearly the description of a volcanic eruption, for throughout the bible things are described as they appear to be. when moses speaks of brimstone and fire being rained upon sodom and gomorrah out of heaven, he is describing the phenomenon as it would appear to one looking at it. of course, we know that in volcanic eruptions such things come to the earth through the crater of the volcano. the lava is thrown high into the air, and the hardening, but still red hot, ashes, rain down on the earth from the ash cloud that forms over the mountain. but, looked at from a distance they appear to fall or be rained down from the skies. in exactly the same way, livy, the roman historian, tells about showers of stones that fell from heaven on mt. albano near rome for two whole days during the second punic war. so, too, even pliny, who had some pretensions to be considered a naturalist, in describing the appearance of mt. vesuvius during the terrible eruption of a. d. , when herculaneum and pompeii were destroyed, speaks of the red hot stones and ashes as falling from above. so, in reality, they did, although, as in the case of the cities of the plain, the materials forming the cloud came from the crater of the volcano below. as to brimstone falling from the sky, this is by no means an unusual occurrence during many volcanic eruptions, since sulphur is a common material, often thrown out of the craters of some volcanoes. note also the statement that, when abraham rose early in the morning and looked toward the place where sodom and gomorrah stood, he saw the smoke of the country go up like the smoke of a furnace. this was, probably, the smoke caused by the burning of the city, or even by the destruction of the crops in their fields, when ignited by the falling red hot ashes. it might also have been partly due to the burning of asphalt thrown out from the fissures in the ground, or to the showers of volcanic ashes that fell from the cloud formed during the eruption. that the cities there were destroyed by a volcano far in the past appears from things outside of the bible proper; for strabo, the greek geographer, refers to jewish traditions that thirteen flourishing cities were swallowed up by a volcano, and this finds fair corroboration in the ruins along the western borders of the dead sea. a writer referring to these eruptions says: "the eruptions themselves have ceased long since, but the effects, which usually succeed them, still continue to be felt at intervals in this country. the coast in general is subject to earthquakes, and history notes several which have changed the face of antioch, laodicea, tripoli, berytus, tyre, and sidon. in there happened one which spread the greatest ravages. it is said to have destroyed in the valley of balbec upwards of , persons." attention has already been called to the fact that the valley of the jordan occupies a depressed or sunken region far below the level of the mediterranean and the red seas. it is the belief of some geologists that this depression was caused by an earthquake which accompanied the volcanic eruption that destroyed sodom and gomorrah and the cities of the plain. indeed, some contend that the present site of the valley of the jordan, including the sea of tiberius and the dead sea, is a great fissure that was made in the limestone of the valley during the time of that earthquake. it would appear from the peculiar geography of this section of country that the jordan river has not always emptied into the dead sea, but that before the time of the destruction of the cities of the plain the greater part of the country now occupied by the dead sea was a fertile valley, and the jordan emptied directly into the red sea at the gulf of akaba; that during the disturbance through changes in the valley, or possibly by a lava stream flowing across a portion of the bed of the lower jordan, or even by a huge accumulation of stones or ashes thrown out from a neighboring volcano, the discharge of the river into the red sea was cut off, and that in this way the waters of the rivers began to accumulate and to flow over the plain, thus forming the basin of the dead sea. there is no difficulty in accounting for the saltness of the dead sea. there are large quantities of salt, and salty matters generally, in the volcanic rocks of the region, but, even if this were not so, when a river empties into a lake with no outlet to the sea, and which therefore loses its water by evaporation only, the water will gradually become very salt, since the remaining waters of such a lake contain more or less salt, while the water they lose by evaporation contains none. the waters of the dead sea are very salt, but not the saltest in the world. in every pounds of dead sea water twenty-four pounds consist of salty matters. the waters of the great salt lake, in utah, contain eighteen per cent of salty matters. lake van, in eastern turkey, is, perhaps, the saltest lake on earth, it containing no less than thirty-three pounds of salty substances in every pounds of water. daubeny, an authority on volcanoes, and quite competent to give an opinion concerning what is possible in this line, describes what he believes took place, as follows: "briefly then to recapitulate the train of phenomena by which the destruction of the cities might have been brought about, i would suppose that the river jordan, prior to that event, continued its course tranquilly through the great longitudinal valley, called el arabah, into the gulf of akaba; that a shower of stones and sand from some neighboring volcano first overwhelmed these places; and that its eruption was followed by a depression of the whole of the region, from some point apparently intermediate between the lake of tiberius and the mountains of lebanon, to the watershed in the parallel of °, which occurs in the valley of el arabah above-mentioned. i would thence infer that the waters of the jordan, pent-up within the valley by a range of mountains to the east and west, and a barrier of elevated table-land to the south, could find no outlet, and consequently by degrees formed a lake in its most depressed portion, which, however, did not occur at once, and therefore is not recorded by scripture as a part of the catastrophe, though reference is made in another passage of its existence _in what was before the valley of siddim_." as regards the turning of lot's wife into a pillar of salt, henderson, who has carefully studied this part of the country, remarks: "how natural is the incrustation of his wife on this hypothesis! remaining in a lower part of the valley, and looking with a wistful eye towards sodom, she was surrounded, ere she was aware, by the lava, which rising and swelling, at length reached her, and (whilst the volcanic effluvia deprived her of life) incrusted her where she stood, so that being, as it were, embalmed by the salso-bituminous mass, she became a conspicuous beacon and admonitory example of future generations." chapter xxxi instruments for recording and measuring earthquake shocks to attempt by the unaided senses a determination of the direction in which earthquake shocks reach any certain spot, the velocity with which they are travelling, their degree of intensity, their general character, whether horizontal or vertical, or any peculiarities which might show them to be exceptional would be futile for more reasons than one. even a skilled scientific observer, familiar with what has already been discovered and eager to discover more, might in the excitement of an earthquake become so excited himself as to make him unable to take reliable observations. but human ingenuity has succeeded in devising delicate instruments capable of recording not only the exact time of the arrival of an earthquake shock, but also of measuring the different parts of what may seem to be a single shock, the direction in which the shocks reach the place, as well as the variations of intensity in all the shocks. crude instruments to do some of these things have been in use from very early times. according to mallet among the more important of these early instruments was the following: the instrument of cacciatore of palmero. this consisted of a circular wooden dish, about ten inches in diameter, placed horizontally, and filled with mercury to the brim of eight notches at equal distances apart. beneath each notch was placed a small cup. on the passage of the earthquake waves the vessel, being tilted in a direction dependent on the direction in which the waves were travelling, would cause some of the mercury to spill over into one or more of the cups, thus indicating by its amount the intensity of the wave, and by the particular cup or cups that were filled, the direction in which the waves reached the place. somewhat similar contrivances were of a vessel partly filled with molasses, or other sticky liquid; or a cylindrical tub, the sides of which were chalked or whitewashed and filled with some colored liquid. in either of these cases, on the passage of the earthquake waves, the vessels were tilted and showed by the height of the marks the intensity of the waves, and by the position of the marks the direction in which the waves first reached the instrument. these instruments, though satisfactory for the study of earthquake shocks a long time ago, when an earthquake was regarded as practically consisting of but a single shock, or, at the most, of a very few shocks, would be worthless for the study of earthquakes now, for it is finally known that an earthquake consists of a series of many hundreds of vibrations, differing greatly in their rapidity and intensity, and following one another in a definite order. the old forms of earthquake instruments were known as _seismoscopes_. the word seismoscope is a compound word from greek consisting of the two words, seism and scope. it means literally any instrument capable of seeing, or calling attention to, a seism, or _earth-shake_. in other words, a seismoscope is any instrument capable of calling attention only to an earth-shake. of course, neither of the rude seismoscopes just mentioned would be able to give any valuable indications of the successive shakings to which the vessel containing the viscid liquid had been subjected, since the liquid would simply be splashed a number of times over the same parts of the vessel. in order to get a record of the successive shocks another form of apparatus must be employed, a form known as a _seismograph_. concerning the complex character of the apparently single earthquake shock, professor milne makes this highly interesting and picturesque statement: "an earthquake disturbance at a station far removed from its origin shows that the main movement has two attendants, one which precedes and the other which follows. the first of these by its characteristics indicates what is to follow, whilst the latter, in a very much more pronounced manner, will often repeat at definite intervals, but with decreasing intensity, the prominent features of what has passed. inasmuch as these latter rhythmical, but decreasing, impulses of the dying earthquake are more likely to result from reflection than from interference, i have provisionally called them echoes." there are many different forms of instruments known as seismographs that are capable of recording all of these vibrations, but there is this objection to their use: that the records appear in so tangled a form that it is practically impossible to decipher or untangle them. this fact can be grasped by examining fig. , which represents a record of this kind. [illustration: fig. . complex record of seismograph] it is necessary, therefore, to employ a modified form of instrument called a _seismometer_, able not only to record all the different vibrations, but to record them in such a manner that they can be easily recognized. fig. , for example, shows results obtained by the use of a seismometer, in which the different vibrations are separated, and so recorded on a sheet of paper, as to be readily understood. such a record is called a _seismogram_, and represents a _long distance seismogram_. here the large arrow indicates the beginning of the record. and herein, as can be clearly seen, what would appear to an observer without an instrument only a single shock, lasting but the fraction of a minute, in reality consists of the _preliminary shake_ as represented in ab and bc, the _principal shake_, as represented at c, d , d , and d , and the _final portions of the shake_ or the "echoes" of professor milne, as represented from d to e. [illustration: fig. . long distance seismogram] except in a very general way there is for present purposes no need of explaining the construction and operation of the seismometer and seismograph. suffice it to say, there are many forms of these instruments, any of which are capable of recording the details of a passing shock. the most important thing in either a seismograph or a seismometer is to obtain what is known as a _steady point_; that is, a point consisting of some object or mass that will remain practically at rest, while everything around it, even the support which holds it, is affected by the earthquake. it is, of course, not very easy to obtain a steady point, but it can be done; and it will be at once comprehended that if a plate or piece of paper were attached to such a steady point or mass, and a pencil or tracer had one of its ends resting on the plate, and its other end attached to the support that vibrates with the earth, a tracing or record would be drawn on the plate from which the character of the motion of the end of the tracer, and, therefore, of the earth, would be marked on the plate. [illustration: fig. . vicentini vertical pendulum] various devices have been employed for the steady points. the most successful consists of a heavy mass of lead. fig. represents a form of instrument invented by professor vicentini of italy. here the steady point consists of a heavy leaden bob, of , , or even kilograms, suspended by three metallic rods united above by a brass cap, hung on a steel wire to a bracket fixed on the wall. this wire may have a length as great as fifty feet. [illustration: fig. . vicentini pendulum and recorder] fig. represents the recording instrument. here a tracer is provided that is capable of multiplying the motion fifty times, or even eighty times. a record is traced on a sheet of paper passing over a roller which imparts a rapid motion to a sheet so as to make sure that the different parts of the shock or vibration will be recorded on separate portions of the paper. chapter xxxii seaquakes as earthquakes are shakings of the earth's crust in places where it is uncovered by the waters of the ocean, so _seaquakes_ are the shakings of those portions that lie on the bed of the ocean. mallet points out that the earthquake wave may start either in the interior of the continent, or on the bed of the ocean; that the latter place is the more common, since on the land vents--rude safety-valves, as it were,--are provided by the craters of the volcanoes; that, when earthquakes start on the ocean bed, the impulses are conveyed in different forms of waves, i. e., those through the solid earth, those through the water, and those through the air, with varying sounds like bellowings and explosions, or like the rolling of wagons over rough roads. to learn when quakes occur on the sea is a much harder task, since on the land we can use seismoscopes, seismographs, or seismometers to indicate, record, or measure the shakings of the crust, while on the sea, where the water is always in more or less motion and the surface so far from the ocean's bed this is impossible, or, rather shall it be said, has hitherto been found so; for that the mind of man may surmount this obstacle is not impossible to conceive. to detect the wave produced by the quaking of the bed of the ocean is exceedingly difficult, since those in very deep water are flat or possess but a small height. indeed, in the deepest parts of the ocean this height is probably to be measured only by inches instead of feet. when, however, the waves advance towards the shore they increase in height, and when they reach the shallows near the coast, they begin to curl over and break, thus creating the enormous waves mentioned so often as attending great earthquakes in the ocean. during the great earthquake of simoda in japan, , the waters of the bay were first greatly agitated, and then retreated, leaving the bottom bare in places where the water was formerly thirty feet deep. a wave, thirty feet high, then rushed in from the bay and, climbing the land, swept away everything in its path, covering the town with water to the tops of the houses. this monster wave then receded, but rushed back five times. in , an earthquake wave suddenly entered callao, the port of lima, peru, sinking twenty-three vessels and driving a frigate inland, where it was left high and dry. this wave extended across the pacific to the hawaiian islands, a distance of , miles. on the th of august, , an earthquake wave, that started a short distance from shore, produced a number of earthquake waves sixty feet high that reached the coast of peru half an hour after the principal earthquake shock. these waves reached coquimbo, miles distant, in about three hours, and honolulu, on the sandwich islands, , miles distant, in twelve hours, and the coast of japan, more than , miles distant, on the next day. le conte remarks that these waves would have encircled the earth, had it not been for the barrier interposed by the andes. another great seaquake, known as the iquiqui seaquake, during in the same neighborhood damaged severely the towns of north chile and southern peru. while, however, there is difficulty in readily observing the earthquake waves that form in the deep ocean, yet such is at times the violence of an earthquake that there is no difficulty in detecting its presence, even in deep water. dr. rudolph has made a careful study of the evidences of earthquakes produced in the deep sea, from a careful examination of a great number of the logs of ships. logs, as everybody knows, are books in which the captain or commanding officer makes careful entries of all important happenings to the vessel, conditions of the weather and of the sea. from this source dr. rudolph obtained considerable information of much value concerning these phenomena. i have already called your attention to portion of the atlantic ocean lying near the equator, in the warmest part of the ocean, between africa and south america, as being a region especially liable to submarine volcanic showers. while, generally speaking, there is nothing in this region to indicate the probability of submarine disturbance, yet suddenly, if a vessel happens to pass directly over the point of origin of the quake, there ensues a great quaking or quivering. loose objects on the ship begin to shake and clatter. noises arise from some invisible point deep down in the ocean. the disturbance grows, the noises begin to resemble distant thunder, the ship trembles and staggers as though it had struck rocks, and many believe she is about to go down; when, as suddenly as it began, the commotion ceases, the noises stop, and the ship shapes her course as calmly, and as gallantly, as before. rudolph gives two excellent examples of seaquakes in this region, both of which were, doubtless, due to submarine eruptions. on the th of january, , as the ship _florence_ was in lat. ° ' n., long. ° ' w., about ten miles n. w. by n. from st. paul's rock, the people on board felt a sudden shock that began with a rumbling sound like distant thunder. this lasted only forty seconds. the glass and dishes of the vessel rattled so violently that it was feared they would be broken. the shakings were so strong that several objects on the vessel were thrown down. everyone believed the ship had struck on rocks. the captain leaned over the taffrail in order to see the position of the reef, but soon saw that the vessel had struck nothing, and informed his crew "it was only an earthquake shock." another of the log books examined by rudolph was that of a ship in the same part of the atlantic ocean. this record showed that suddenly on a morning, in , strange noises were heard that soon increased and became not unlike the firing of great guns or the peals of distant thunder. the ship vibrated as if its anchor had been suddenly let go, and at the same time a feeling came over all the crew, as if they had been electrified. in some cases the vibrations were sufficiently severe to throw heavy objects from the deck, as appears in an account given by a french geologist of a quake in the mediterranean off the shores of asia minor. "our ship was over the epicentre,"[ ] he says, "and was so severely shaken that at first the admiral feared the complete destruction of the corvette." he then makes the statement that the shocks which were directly upwards were so strong as to throw heavy objects in the air; for example, a heavy gun and its carriage. while it is possible, as dutton remarks, that this incident of the heavy gun and carriage was grossly exaggerated, yet it should not be forgotten that in the case of submarine eruptions such as that which resulted in the production of the island of sabrina, an immense column of water, weighing probably many times more than a gun and its carriage, was observed to be shot high into the air. where the seaquake is produced by a strong submarine volcanic eruption, there is a violent commotion of the water itself, so that a vessel passing over such a point may be greatly injured, and, indeed, even destroyed. such disasters, however, are fortunately exceedingly rare. among other common effects of seaquakes is the destruction of fish already mentioned by the sudden blow to the water stunning and killing them, just as the explosion of dynamite or other high explosives does in a lake or pond. the most marked effect, however, of seaquakes is the starting of the great wave on the coasts of continents and islands. there are certain parts of the ocean that are especially liable to seaquakes. some of the more important of these, as shown by rudolph's researches, are: the region already referred to in the narrowest parts of the atlantic ocean between africa and south america almost immediately under the equator. here there are two well marked regions. one is in lat. ° n., long. ° w., where there is a submarine ridge, the tops of which form what are known as st. paul's rock. the ocean here is very deep, the slopes of the ridge descending rapidly. it is on these slopes that earthquakes are very apt to occur just as they do on the steep slopes of mountain ranges. the other region, called by rudolph the _equatorial district_, lies a little further to the east on both sides of the equator in long. ° w. it appears from rudolph's researches that between and no less than thirty-seven seaquakes were reported in the logs of ships in the neighborhood of st. paul's rock, and between and , in the equatorial district, there were forty-nine seaquakes. it must not be supposed, however, that these were all the quakes in the regions during these times, since, of course, many shocks must have happened that were not felt even by vessels in the neighborhood and many more, when this portion of the ocean was free from any craft. in the north atlantic there is a portion of the ocean's bed known as the _west indies deep_. here the bed is marked by great depths and by many irregularities and is, therefore, a region where seaquakes are common. still another district is found in the north atlantic in the neighborhood of the azores. this is the region in which the lisbon earthquake is believed to have started. another region where seaquakes are common is in the pacific along the coast of south america from the equator to ° s. lat. "here," says dutton, "especially in the vicinity of the angle where the peruvian and chilian coasts meet have they been most numerous and formidable. the harbors of pisco, arica, tacua, iquiqui, and pisago have been repeatedly subject to these destructive invasions." there has been considerable discussion as to the exact manner in which the earthquake waves are set up. whatever be the cause or causes, the action must be sudden, such as an upheaval of the bottom, or a collapse of a large section of the ocean's bed, with a dropping of a vast body of water. or, possibly, a submarine volcanic eruption causes the water to lift suddenly under pressure of steam generated by escape of the lava and other hot volcanic products. dr. rudolph attributes earthquake waves to submarine volcanic eruptions alone. it would seem, however, as if each one of the other things above referred to might at times be the direct cause. chapter xxxiii the distribution of earthquakes earthquakes may occur at any part of the earth's surface, at any time of the day, or at any season of the year, yet they are more frequent at certain parts, certain hours, certain seasons. since some earthquakes are unquestionably connected with volcanic eruptions, a map or chart of the volcanoes of the earth would also, to a certain extent, show the parts of the earth that are likely to be visited by earthquakes. since, however, by far the most severe earthquakes are not directly connected with volcanoes, but are due to sudden slips of faulted strata, a volcanic chart would necessarily fail to indicate accurately the principal earthquake regions. in the preparation of a map showing the distribution of earthquakes over the earth's surface, mallet adopted the plan of colorings or tintings in such a manner that the depth of the colors would represent not only the parts shaken, but also the relative number of times shaken, as well as the intensity of the shocks. in order to determine the depth of tint to be employed, mallet divided earthquakes into the following classes according to their intensity: _great earthquakes_, or earthquakes of the first class; or those in which the area affected is of great size, in which many cities have been overthrown, and many people killed, and parts of the surface greatly altered. _intermediate earthquakes_, or those in which, although the area affected is great, yet the destruction of buildings, or loss of life, has been comparatively small. _minor earthquakes_, or those which, although capable of producing small fissures in the crust, generally leave but few or no traces of their occurrence. the greatest distance to which earthquake waves of the first class extend is taken by mallet as being over a diameter of , miles; those of the second class over a diameter of about miles, and those of the third class over a diameter of about miles. according to the rossi forel scale already given, earthquake shocks are divided according to their relative intensity into ten separate classes, viz.: i. the micro-seismic; ii. the extremely feeble; iii. the very feeble; iv. the feeble; v. the moderately intense; vi. the fairly strong; vii. the strong; viii. the very strong; ix. the extremely strong; x. shocks of extreme intensity. an earthquake map prepared according to mallet's scale would show a greater depth of color or tint in the neighborhood of the volcanic districts of the earth and especially in the neighborhood of the mountain regions, where tectonic quakes are most frequent. oceanic areas would be left almost untinted, not because earthquakes do not occur on the bed of the ocean, but because of the difficulty of observing such earthquakes at great distances from the land. so far from earthquakes being absent on the bed of the ocean it is most probable that they are more frequent there than elsewhere. prepared in this way, mallet's map would show a preponderance of earthquakes along the borders of the continents, especially along the "great circle of fire" on the borders of the pacific ocean. dutton as well as some others assert that the "great circle of fire" on the shores of the pacific has in reality no existence; that, instead of there being a continuous region of volcanoes, there is in reality nothing more than a considerable number of volcanoes arranged in groups along the borders of this ocean, but separated by spaces containing no marked volcanic activity. we do not think this a tenable position, since it is well known that volcanoes lie along great lines of fissures at different points or openings which are kept open by subsequent volcanic activity, while the remaining portions are closed soon afterwards; and, moreover, in parts of these so-called non-volcanic regions, there are probably extended regions of extinct volcanoes. since the time of mallet many maps have been made to show the distribution of earthquakes. among the best of such is that by m. de montessus de ballore. some idea of the great amount of work required for the preparation of montessus' map may be formed when one learns that the catalogue of earthquakes collected by him for this purpose included for the years to , , quakes. de montessus' earthquake map divides the grand divisions of the earth into numerous sub-divisions, too numerous, indeed, for even brief description in a work of this kind. from the map he thus laboriously prepared de montessus drew the following general conclusions: . the parts of the earth that are most apt to be shaken by earthquakes are those which possess the greatest differences of relief between their highlands and lowlands, and that in such regions the most pronounced earthquakes are found on the steepest slopes. . earthquakes are most common along those parts of the crust that are thrown up in huge wrinkles, or mountain ranges, whether these masses be above the level of the sea or are covered by it. [illustration: fig. . davison's earthquake map of japan] . earthquakes are more common in mountainous districts than in plains. but not all mountains are characterized by earthquakes nor are all plains free from them. sometimes the plain at the base of the mountain appears to be especially liable to shocks, probably by reason of slips along faults at these points. the great mountain ranges of the world are generally characterized by unequal slopes, the long gentle slope facing the interior of the continents, and the short, abrupt slopes being turned towards the coast. now, montessus points out that volcanoes are the most frequent on the short, abrupt slopes. in some cases, however, where the long slopes are the roughest, it is these slopes that are most frequently shaken. the beds of the ocean that lie along rapidly descending lines, especially when they lie on the borders of large mountain ranges, are especially liable to earthquakes. dr. charles davison has made a map of the earthquakes of japan in which he had adopted the plan of representing the origin or centres of earthquakes by a series of contour lines like those employed on topographical maps. the advantage of this type of map over that employed by mallet is just this: davison's earthquake map of japan in which the active volcanoes are marked by dots, and the earthquakes by contour lines surrounding the points of origin, discloses the interesting fact that here the positions of the volcanoes and the earthquake centres coincide, since the mountainous districts where the active volcanoes are numerous are singularly free from earthquakes. this can be seen from an inspection of fig. . chapter xxxiv the causes of earthquakes earthquakes occurred long before man appeared on earth. it is natural, therefore, that our early ancestors, experiencing these unwelcome phenomena, vaguely endeavored to explain their causes. these early attempts at explanation have in many cases been of an exceedingly fanciful character. the ancient mongolians and hindoos declared that earthquakes are due to our earth resting on a huge frog and that they occur whenever the frog scratches its head. in japan, where earthquakes are very common, the ignorant people even at a much later day declared that there exists in the depth of the sea an immense fish which, when angry, dashes its head violently against the coast of the island, thus making the earth tremble. this is, doubtless, the biggest fish-story extant. another folk-lore explanation in japan attributes the cause of the tremblings of the earth to a subterranean monster whose head lies in the north of the island of hondo, while his tail lies between the two principal cities. the shaking of his tail causes earthquakes. fantastic and foolish as these explanations are, it is worthy of note that the first of the japanese explanations shows no little observation on the part of the people, since it locates the starting-points of earthquakes as being not on the land, but on the bottom of the sea. in point of fact, nearly all the great earthquakes in japan seem to start somewhere between the coasts of the islands on the sea-bottom that leads down to a very deep part of the pacific known as the tuscarora deep. many years ago nearly everyone believed that earthquakes were caused solely by the forces that produce volcanic eruptions; that all earthquakes, whether in the neighborhood of active volcanoes, or at great distances therefrom, were to be regarded solely as volcanic in their origin. it is now recognized that the most severe and far-reaching earthquakes have no immediate connection with volcanic explosions, but are due to the sudden slippings of the earth's strata over lines of faults; or, in other words, earthquakes are most frequently of the tectonic type. at the present time there is unfortunately much difference in opinion as to the exact cause of earthquakes. by this is not meant the immediate cause, but the ultimate cause. as to the immediate cause, practically all are agreed that quakes of volcanic origin are to be traced to the same forces that produce volcanic eruptions, while quakes of tectonic origin are due directly to the slipping of the strata along the faults. but when inquiry is instituted as to the nature of the forces that cause the volcanic eruptions, or that produce such an alteration of the strata as permits them afterwards to slip and thus jar the earth, there is much difference of opinion. as can be seen from a few quotations of well-known authorities, only two kinds of earthquakes exist; namely, volcanic earthquakes and tectonic earthquakes. dana, for example, while acknowledging that small earthquakes may be caused by the sudden falling of large rock masses into cavities in the crust of the earth, says: "but true earthquakes come, for the most part at least, from one or the other of the following sources of disturbance. " . vapors suddenly produced, causing ruptures and friction. " . sudden movements or slips along old or new fractures. "earthquakes due to the former of these methods are common about volcanoes, and at the hawaiian islands shakings that are destructive over the island of hawaii at the moment of some of the more violent eruptions, do not often affect the island of oahu, a depth of fathoms of water, the least depth between the two islands, being sufficient to stop off the vibrations.... "earthquakes of the second mode of origin may occur in all regions, volcanic or not. they have their origin mostly in the vicinity of mountain regions, where old fractures most abound. the vibrations may begin in a slip of a few inches, in fact; but where there has been a succession of slips, up and up from , feet or more, as in the appalachian, earthquakes of inconceivable volcanic activity must have resulted." dana points out that volcanoes stand on lines of fractures in the openings of which their existence began and that, during geological time, slips up or down these fractures have occurred, producing earthquakes and possibly starting eruptions. prestwich, a well-known english geologist, speaks very decidedly concerning the causes of earthquakes: "for my own part, i am disposed to share the belief expressed by dana that the tension or pressure, by which the great oscillations or plications of the earth's crust have been produced, have not entirely ceased; and that this is generally the most probable cause of earthquakes. the uplifting of the great continental tracts and mountain ranges must have always left the interior of the crust in a state of unstable equilibrium, and any slight slide or settling along an old fracture, or in highly disturbed and distorted strata, would be attended by an earthquake shock. "in volcanic areas the removal of the large volumes of molten rock from the interior to the surface must produce settlements and strains which might also result in some of these minor earthquakes to which volcanic districts are so subject. where we have the two conditions combined, as they are in the andes in south america, these earthquake phenomena are, as we should expect, developed on the grandest and widest scale." geikie, the scotch geologist, says: "various conceivable causes may, at different times and under different conditions, communicate a shock to the subterranean regions. such as the sudden flashing into steam of water in the spherodial state, the sudden condensation of steam, the explosion of a volcanic outpour, the falling in of the roof of a subterranean cavity, or the sudden snap of deep-seated rocks subjected to prolonged and intense stress." sir charles lyell, the great english geologist, holds the following views concerning the origin of earthquakes. he speaks as follows in his "principles of geology": " . the primary cause of the volcanoes and the earthquakes are to a great extent the same, and connected with the development of heat and chemical action at various depths in the interior of the globe. " . volcanic heat has been supposed by many to be the result of the high temperature which belonged to the whole planet when it was in a state of igneous fusion, a temperature which they suppose to have been always diminishing and still to continue to diminish by radiation into space.... "the powerful agency of steam or aqueous vapor in volcanic eruptions leads us to compare its power of propelling lava to the surface with that which it exerts in driving up water in the pipe of an icelandic geyser. various gases also, rendered liquid by pressure at great depths, may aid in causing volcanic outbursts and in fissuring and convulsing the rocks during earthquakes." major clarence edward dutton, u. s. a., an acknowledged authority on seismology, speaks as follows: "thus far, then, we have two causes of earthquakes which are apparently well sustained: ( ) the downthrows, which have often been observed to be accompanied by earthquakes, and ( ) volcanic action. but neither of them have been shown to be connected with more than a comparatively small number. much the greater part of the earthquakes still require explanation, and the indications are manifold that some of them are produced by some cause yet to be stated." he acknowledges, however, this unknown cause may be traceable to volcanic agency. to quote him in full: "it remains now to refer to the possibility that many quakes whose origin is unknown, or extremely doubtful, may, after all, be volcanic. this must be fully admitted, and, indeed, it is in many cases highly probable. evidences that volcanic action has taken place in the depths of the earth without visible, permanent results on the surface abound in ancient rock exposures. formations of great geological age, once deeply buried and brought to daylight by secular denudations, show that lavas have penetrated surrounding rock-masses in many astonishing ways. sometimes they have intruded between strata, lifting or floating up the overlying beds without any indication of escaping to the surface. sometimes the lava breaks across a series of strata and finds its way into the partings between higher beds. or it forces its way into a fissure to form a dike which may never reach the surface. in one place a long arm or sheet of lava has in a most surprising and inexplicable manner thrust itself into the enveloping rock-mass, and in the older or metamorphic rocks these offshoots or apophyses cross each other in great numbers and form a tangled network of intrusive dikes. in other places the intruded lava has formed immense lenticular (lense shaped) masses (laccolites), which have domed up the overlying strata into mountain masses. these intrusions, almost infinitely varied in form and condition, are often, in fact usually, inexplicable as mechanical problems, but their reality is vouched for by the evidence of our senses. what concerns us here is the great energy which they suggest and their adequacy to generate in the rocks those sudden, elastic displacements which are the real initiatory impulses of an earthquake. they assure us that a great deal of volcanic action has transpired in past ages far under ground, which makes no other sign at the surface than those vibrations which we call an earthquake." koto, the celebrated japanese student of earthquakes, and a member of the earthquake investigation committee appointed by the japanese government for studying the great mino-owaro earthquake, in japan, , is properly regarded as an authority on earthquakes. living, as he does, in a country where earthquakes and volcanic eruptions are of almost daily occurrence, he has had abundant opportunity for studying these phenomena, especially in connection with the seismological institute of japan. he speaks as follows: "to make clear once for all my own standpoint, i may say plainly that the chain of volcanoes and the system of mountains of the non-volcanic earthquake, appear to me to have very intimate and fundamental relations with the so-called tectonic line." mallet regards earthquakes that can be directly traceable to volcanic origin as unsuccessful efforts on the part of nature to establish volcanoes. he speaks concerning this matter as follows: "an earthquake in a non-volcanic region may, in fact, be viewed as an uncompleted effort to establish a volcano. the forces of explosion and impulse are the same in both; they differ only in degree of energy, or in the varying sorts and degrees of resistance opposed to them. there is more than a mere vaguely admitted connection between them, as heretofore commonly acknowledged--one so vague that the earthquake has been often stated to be the cause of the volcano (johnson, 'phy. atlas,' geology, page ), and more commonly the volcano the cause of the earthquake, neither view being the expression of the truth of nature. they are not in the relation to each other of cause and effect, but are both unequal manifestations of a common force under different conditions." before closing this chapter on the causes of earthquakes it may be well to state briefly the explanations that have been suggested by those who hold that the earth is solid and cold throughout its entire mass, except that in the neighborhood of volcanic districts there are limited areas situated only a comparatively few miles below the surface where the rocks are highly heated. professor mallet suggested that the source of heat for these local areas of melted rocks was to be found in the enormous mechanical force that is developed by the crushing of the strata in the earth's crust. the principal objection to mallet's theory is to be found in the fact that, for this heat to be available for the melting of rocks, it must be produced rapidly, and not spread out over long periods of time. moreover, there would appear to be no other way to account for the production of the great force required to effect the crushing of the earth's strata save on the assumption of a highly heated interior still cooling and contracting. in his "aspects of the earth" shaler has suggested an hypothesis that may be regarded to a certain extent as explaining how heat, slowly generated, might be blanketed, or prevented from escaping and so possibly reaching a temperature sufficiently high to melt the materials in portions of the interior not far below the surface of the earth. "we thus see that in the water imprisoned in the deposits of the early geological ages and brought to a high temperature by the blanketing action of the more recently deposited beds, we have a sufficient cause for the great generation of steam at high temperatures, and this is the sole essential phenomenon of volcanic eruptions. we see also by this hypothesis why volcanoes do not occur at points remote from the sea, and why they cease to be in action soon after the sea leaves their neighborhood.... "the foregoing considerations make it tolerably clear that volcanoes are fed from deposits of water contained in ancient rocks which have become greatly heated through the blanketing effects of the strata which have been laid down upon them. the gas which is the only invariable element of volcanic eruptions is steam; moreover, it is the steam of sea-water, as is proven by analysis of the ejections. it breaks its way to the surface only on those parts of the earth which are near to where the deposition of strata is lifting the temperature of water contained in rocks by preventing, in fact, the escape of the earth's heat." another very common theory is that of chemical action, or the heat produced by the oxidation of various substances inside the earth, such, for example, as iron pyrites, a compound of iron and sulphur. when sir humphrey davy discovered metallic sodium and it was found that this material, when thrown on water, possessed the power of liberating intense heat, the discovery was welcomed by geologists as affording a possible explanation of the cause of volcanoes and earthquakes. it may be said generally concerning chemical action as the source of the earth's interior heat, that the chief objection against it is the fact that such heat is liberated too slowly to result in the production of a very high temperature. this objection does not exist in the case of such substances as metallic sodium, since here the heat is rapidly developed and is sufficient in amount to fuse the substances produced. but in the lava produced in such great quantities as it is in volcanic districts there must be liberated at the same time large quantities of gaseous hydrogen. now, although hydrogen is, as we have already seen, sometimes given off with the gases that escape from volcanic craters, yet the quantity which escapes is so small that this theory of volcanic activity has been practically abandoned. quite recently, however, among the various chemical substances that are produced under the extremely high temperatures of the electric furnace have been found, or formed, a number of curious substances such as _calcium carbide_, _calcium silicide_, _barium silicide_, etc., that possess the property of becoming highly heated on coming in contact with water. now it is an interesting fact that the hydrogen and other gases which are given off by the action of water on these substances are absorbed in large quantities by the materials themselves, so that the objection of the absence of hydrogen and similar gases in the craters of the volcanoes would not be quite as objectionable as in the case of such substances. of course, it is impossible to say whether such substances as calcium carbide, etc., actually exist inside the earth's crust, yet, as has been pointed out, the principal condition necessary for their formation, i. e., a high temperature, existed at times long after the earth, assuming the correctness of the nebular hypothesis, was separated from the nebulous sun. there still remains to be discussed the most curious of all possible causes that have been suggested for the presence of the local heated areas at comparatively short distances below the earth's crust; namely, radio-activity. in , henri becquerel, a frenchman, while investigating the power of the x-rays, when passing through certain substances, to produce phosphorescence, or causing the substances to shine in the dark, made the extraordinary discovery that some of the salts of uranium possess the power of emitting a peculiar radiation closely resembling the x-rays, that is able to pass through substances opaque to ordinary light as well as to affect photographic plates. but the most extraordinary part of this discovery was that the salts of uranium apparently possess the power of giving out this radiation continuously without being exposed to the sun's rays. this peculiar property was called _radio-activity_, and was shortly afterwards found to be present in many other substances besides uranium, and notably so in two newly discovered elements known as polonium and radium. now it has been suggested that if there existed somewhere beneath the earth's crust in these locally heated areas, large quantities of radio-active substances, these regions would at last become highly heated, and in this way likely to produce volcanoes and earthquakes. it would not, however, seem that this is probably their true cause. from what has just been said it is clear how exceedingly difficult it has become to explain the source of the earth's interior heat when the fact of the earth's original highly heated condition is denied. we are, therefore, disposed with russell to believe, as stated in the first part of this volume, that the ultimate cause of both volcanoes and earthquakes is to be found in the gradual cooling of an originally highly heated globe, and that the greater part of the interior is still in a highly heated condition, hot enough to be melted but yet in a solid condition by reason of the great pressure to which it is subjected. chapter xxxv earthquakes of the geological past--cataclysms there were numerous volcanoes in the geological past; therefore, since volcanic eruptions are generally attended by earthquake shocks, it follows that during that remote past the earth has been violently shaken by earthquakes. indeed, if we assume, as we believe to be the case, that the cause of earthquakes is correctly to be traced to an originally heated globe which is gradually cooling, it follows that the earth was necessarily subject to great earthquakes almost from the time when it began to cool. but to establish as a fact the occurrence of an earthquake at so remote a time in the earth's history is far more difficult than to detect the occurrence of a volcano at that time. while the earthquake shocks may produce fissures in the earth's crust, and may be accompanied by great changes of level, yet the great time that has elapsed between such occurrences and the present would permit the various geological agencies that are at work either to cover these fissures completely, or completely to remove by erosion, or in other similar ways, the rocks in which they occurred. it is different in the case of a volcano; for the volcanic craters are in many cases still left standing, and then there are the voluminous sheets of lava that have spread over great areas of the earth, as well as numerous volcanic cones. besides, there are thousands of square miles of surface that have been covered, often to great depths, by deposits of volcanic dust thrown out at one time or another from the craters of the then active volcanoes. i am sure you will acknowledge that any force capable of causing great cracks or fissures in the earth's crust, must, while doing this, have produced violent shakings of the earth. great cracks or fissures are to be found in the rocks of all the geological formations. these are a record of the earthquakes that must have attended these convulsions. and there is plenty of evidence to show that the earth's crust has been torn into these fissures in places deep down below the present surface; for, by the action of water, many of these portions have been uncovered so that these great cracks or fissures which have been afterwards filled with a molten rock that has hardened can be seen in the great dikes that still remain. but there are still other evidences of the existence of earthquakes during the geological past. there are found in the different strata of the earth's crust fossil remains of the plants and animals that lived on the earth long before the creation of man. by a careful study of these fossils we know positively the kinds of animals and plants that lived on the earth, in its waters, or in its atmosphere, when these strata were being deposited. it is in this way possible for a geologist to trace the life of the earth and its development as it is written on the great book of which the earth's different strata form the separate pages. now, a careful study of the earth's fauna and flora during the geological past, shows, beyond any question, that occasionally great changes have occurred in the earth; for, here and there, during different times, we find that certain species of animals and plants have completely disappeared, to be followed, after certain intervals, by entirely different species. it is evident, therefore, that changes have occurred that have made it impossible for the animals and plants that formerly lived on the earth to exist under the changed conditions. these occurrences are known to geologists as _exterminations_, _catastrophes_, or _cataclysms_. they are also sometimes called _revolutions_, for they mark a more or less complete wiping-out of the animals living at the time they occurred. if you will try to think you will readily understand how great a catastrophe must be, that would be able to wipe out or completely destroy an entire race of animals. you have doubtless read with astonishment the terrible catastrophe that accompanied the eruption of krakatoa, especially at the loss of life and property caused by the great waves that were set up in the ocean, but far reaching as these losses were they have nevertheless affected but a limited portion of the earth. the plain truth is even more stupendous, for catastrophes of the geological past appear to have been so far-reaching and powerful as to affect the whole surface of the earth, and to have annihilated entire races of animals and plants as if they had never existed. geologists are all practically agreed that there are only two ways in which such exterminations of the earth's life could have been caused, and these are changes in the earth's climate, or the starting of waves in the sea by great earthquakes. in the sea; for it must be borne in mind that in the geological past the greater part of the earth's surface was covered by water, and the land areas were comparatively small and low, so that waves created by earthquakes might easily have overwhelmed the entire land surface. of course, it is fair to suppose that in many cases these exterminations may have been caused by sudden changes of climate, such as would naturally have resulted from any change in the direction of hot ocean currents which formerly flowed from the equator to the poles. the appearance of a fairly large mass of land in the central parts of the ocean might readily have turned aside the hot ocean currents that formerly swept over the polar regions, thus greatly lowering the earth's average temperature in these regions. but it seems probable that the principal cause of the destruction of life in the geological past was produced by earthquake waves in the sea, sweeping over the continents. let us, therefore, examine two of the earth's principal geological revolutions or cataclysms; namely, that which occurred at the close of an early geological time known as the palaeozoic, and that which occurred at the end of a geological time intermediate between the palaeozoic time or the time of ancient life, called the mesozoic time, and the cenozoic time, or the time immediately preceding the present time. these two revolutions are called by dana, _the post-palaeozoic_, or _appalachian revolution_, and the _post-mesozoic revolution_. both were characterized by the making of great mountain systems, and were, therefore, especially liable to repetitions of tremendous earthquakes that must have produced enormous waves in the ocean. "palaeozoic time," says dana, "closed with the making of one of the great mountain ranges of north america--the appalachian, besides ranges in other lands, and in producing one of the most universal and abrupt disappearances of life in geological history. so great an event is properly styled a revolution." towards the close of the palaeozoic time immense disturbances of the earth's crust occurred during the uplifting of the appalachian mountain system. one may, perhaps, form some faint idea of the immensity of the forces at work, from the fact that there were great faults produced by the uplifting of the lands attended with displacement amounting to , or , feet or more; that in parts of southwestern virginia there were flexure faults miles in length. as to the probability of the extensive exterminations that have occurred during these times being produced by earthquake waves, dana speaks thus: "the causes of the extermination are two.... ( ) a colder climate.... ( ) earthquake waves produced by orogenic movements (movements producing mountain ranges). if north america from the west of the carolinas to the mississippi valley can be shaken in consequence of a little slip along a fracture in times of perfect quiet (the allusion here to the charleston earthquake, in ), and ruin mark its movements, incalculable violence and great surgings of the ocean should have occurred and been often repeated during the progress of flexures, miles in height and space, and slips along newly opened fractures that kept up their interrupted progress through thousands of feet of displacements.... "under such circumstances the devastation of the sea-border and the low-lying land of the period, the destruction of their animals and plants, would have been a sure result. the survivors within a long distance of the coastline would have been few. the same waves would have swept over european land and seas, and there found coadjutors for new strife in earthquake waves of european origin. these times of catastrophe may have continued in america through half of the following triassic period; for fully two thirds of the triassic period are unrepresented by rocks and fossils on the atlantic border." coming now to the post-mesozoic revolution this period was marked by the making of the greatest of the north american mountain systems. dana points out that this revolution affected the summit region of the rocky mountains over a broad belt probably as long as the western side of the continent. this great belt of mountain-making extended from the arctic regions through north america, probably paralleled by like work, of equal extent, in south america, but on a more eastern line. "the disappearance of species," says dana, "at the close of mesozoic time was one of the two most noted in all geological history. probably not a tenth part of the animal species of the world disappeared at the time, and far less of the vegetable life and terrestrial invertebrates; yet the change was so comprehensive that no cretaceous species of vertebrate is yet known to occur in the rocks of the american tertiary, and not even a marine invertebrate." in tracing the causes of these disappearances, dana points out that, perhaps, the principal cause was a decrease in the temperature of the ocean, since the destructions were limited in large measure to marine life. he regards, however, the other most probable cause as traceable to earthquake waves; for the making of a great mountain range along the entire length of the continent resulted in displacements of the rock formations along lines hundreds of miles in length. such displacements must have been attended by a succession of earthquakes of unusual violence, causing the destruction by sudden shocks beneath, and resulting, directly and indirectly, in waves sweeping over the continent. since at this time the land was still low for the greater part, the huge waves must have repeatedly swept over the greater part of the land, leaving only the smaller species of animals and the vegetation. it is evident, therefore, that during the geological past earthquakes occurred that were probably vastly greater than any that have occurred on the earth during more recent times. chapter xxxvi the kimberly diamond fields and their volcanic origin the elementary substance carbon occurs in three forms, i. e., _charcoal_, _graphite_, and the _diamond_. the commonest form of carbon is to be found in charcoal, as well as in bituminous coal, anthracite coal, and _lignite_. graphite, also known as _plumbago_, or _black lead_, is the substance you have seen so often in the lead of pencils. the diamond, as every one knows, is the highly prized precious stone that sparkles so brightly in the light, and is so hard that it is capable of scratching almost any other substance. diamonds are found in various parts of the world. we are now interested in them, however, only as they occur in certain parts of the world, as in the great kimberly diamond fields in southern africa. dr. max bauer in his book on precious stones says that the discovery of diamonds in south africa was made by a traveller named o'reilly, who, in , saw a child sitting in the house of a boer named jacobs, playing with a shining stone. jacob's farm was a short distance south of the orange river near hopetown. this stone proved to be a diamond weighing some twenty-one and three-tenths carats and was afterwards sold for $ , . the incident led to the discovery and consequent development of the kimberly diamond fields. without going into a description of the different deposits in which diamonds are found, it will suffice to say that in the kimberly district the diamonds occur distributed through the materials that fill peculiar funnel-shaped depressions called _pipes_ which extend vertically downward to unknown depths. the rock that fills a pipe consists of an entirely different material from that in which the pipe occurs. the upper extremity of the pipe is generally slightly elevated above the general surface for a few yards. the pipes vary in diameter from twenty to yards, diameters of from to yards being quiet common. in , the diamond-bearing material found in the pipes of the kimberly mines had been excavated vertically downwards a distance of , feet, without any signs of its being exhausted. now, the materials which fill the pipe of the great kimberly mine are practically the same in all the mines in the neighborhood. at the upper part of the pipe the materials show the action of weathering by exposure to the air. here the ground is of a yellowish color. below, the materials have a blue color. according to bauer the diamond-bearing material that fills the upper part of the pipe consists of a soft, sandy material of a light yellow color, known to diamond miners as _yellow ground_, or _yellow stuff_. in the case of the kimberly mine, the yellow ground has a thickness of about sixty feet. below it the material has a blue color and is known as the _blue ground_. this latter material possesses the character of a volcanic _tuff_, which is a hardened clay. it is of a green or bluish green color and has the appearance of dried mud that holds or binds together numerous irregular, tough, and sometimes rounded fragments of a green or bluish black serpentine. the diamonds are found near the surface in the yellow ground, as well as downwards through the blue ground. it was at one time thought that most of the diamonds existed in the yellow ground, and that they would soon disappear entirely at short distances below where the blue ground began. under this belief some of the most valuable claims changed hands at prices far below their true value. it was soon found, however, that large and valuable stones existed in the blue ground, and, indeed, this ground has never been mined to a depth below where valuable diamonds appear. the diamonds occur in very small quantities spread through the yellow and blue grounds. the following statement by bauer will show this: "a striking illustration of their sparing occurrence is furnished by the fact that in the richest part of the richest mine, namely, in the kimberly mine, they constitute only one part in , , , or . % of the blue ground. in other mines the proportion is still lower, namely, one part in , , , a yield which corresponds to five carats per cubic yard of rock." of course, you will desire by this time to know the manner in which the pipes of the diamond mines of south africa have become filled with the diamond-bearing rocks, and particularly what diamonds have to do with a book on volcanoes and earthquakes. dr. emil cohen, who has made a study of these regions, regards the pipes as volcanic vents or chimneys, and that the materials filling the pipes have been brought up from below by volcanic forces. he says: "i consider that the diamantiferous ground is a product of volcanic action, and was probably erupted at a comparatively low temperature in the form of an ash saturated with water and comparable to the materials ejected by a mud volcano. subsequently new minerals were formed in the mass, consequent on alterations induced in the upper part by exposure to atmospheric agencies, and in the lower by the presence of water. each of the crater-like basins, or, perhaps, more correctly, funnels, in which alone diamonds are now found, was at one time the outlet of an active volcano which became filled up, partly with the products of eruption and partly with ejected material which fell back from the sides of the crater intermingled with various foreign substances, such as small pebbles, or organic remains of local origin, all of which became imbedded in the volcanic tuff. the substance of the tuff was probably mainly derived from deep-seated crystalline rocks, of which isolated remains are now to be found, and which are similar to those which now crop out at the surface, only at a considerable distance from the diamond fields. these crystalline rocks from which the diamonds probably took their origin, were pulverized and forced up into the pipes by the action of volcanic forces, and imbedded in this eruptive material, these diamonds either in perfect crystals or in fragments are now found." so far as the volcanic origin of the diamonds of the kimberly diamond fields is concerned, cohen's theory has been generally accepted with the following modifications: that the pipes were not filled by a single volcanic eruption, but by successive eruptions, and that in the case of the kimberly mine, the pipes contain the results of as many as fifteen successive eruptions. there has, however, been another and more important modification proposed to cohen's theory, which is far more probable. it will be noticed that cohen's theory regards the action of the volcanic eruption as only serving to bring fragments of a deep-seated mother rock that contained the diamonds up from below with the material that fills the pipe. now, prof. carvill lewis proposes the following very important change in cohen's theory: that the blue ground does not consist of fragmentary material or tuff, but was forced up from below in the pipe in a molten mass and consolidated on cooling. in other words, the blue ground is filled with an ordinary igneous rock that was solidified in place in the vent or pipe. in the great kimberly mines the surface of the pipe is divided into numerous separate claims, each consisting of a small square lot. there are so many of these claims in the kimberly mine that its surface is honey-combed by numerous square pits. the work is done largely by native kaffirs employed there since the ' 's. as the material was removed from the pit, the adjoining claims were separated from each other by high vertical walls. at a later date, in order to remove the material and separate the lots, high staging provided with ropes and hauling machinery was erected. the number of these ropes is now so great that the mine has the appearance of a huge cobweb. a very extensive series of investigations has been made at a comparatively recent date by prof. henri moissan of france on various chemical products that are obtained under the influence of the high temperatures of the electric furnace. when a powerful electric current is caused to pass through a highly refractory material, that is to say, a material difficult to fuse, such as carbon, it raises it to an extremely high temperature. a still higher temperature can be obtained by causing a powerful current to flow between two carbon rods that are first brought into contact, and then gradually separated from each other, just as they are in the ordinary arc lights employed for lighting the streets of our cities. in the latter way a temperature that is estimated as high as , ° c. ( , ° f.), can be readily obtained. under these very high temperatures some very curious chemical products have been obtained in electric furnaces. these furnaces consist of small chambers made of highly refractory materials closely surrounding the incandescent carbon, or the carbon voltaic arc. among some of the most curious of these products are artificially produced diamonds. moissan, however, was not the first to produce diamonds artificially. as soon as lavoisier had experimentally shown that the chemical composition of the diamond and carbon are the same, efforts were made to convert charcoal into diamonds, and despretz, as early as , by means of the combined influence of a powerful burning glass, the oxyhydrogen blowpipe, and the carbon voltaic arc obtained a very high temperature. he claims by this temperature to have been able to change carbon into a few microscopic diamonds. it is quite possible, in the light of later investigations, that despretz may have been mistaken in his belief that he had actually produced diamonds; but whether this be so or not, he was certainly one of the pioneers in this early transformation of charcoal. theoretically, all that would be required in order to change the non-crystalline form of carbon into the diamond, would be to subject the carbon to a temperature sufficiently high to fuse it and then permit it slowly to crystallize. could this be done, there should be no trouble in transforming any amount of coal into any equal amount of diamonds. but the transformation is by no means as simple as might be supposed. it is not that the temperature of the carbon cannot be raised to its point of fusion, but that as soon as a certain temperature has been reached, the carbon, instead of fusing or melting, is suddenly volatilized or turned into vapor. there is no doubt that this is done. thousands of feet of carbon rods are volatilized every night in the arc lamps of our cities, but the trouble is that this carbon vapor so formed, when cooled, or condensed, is not converted into the exceedingly hard, clear, crystalline diamond, but into the soft, dull black graphite or plumbago. now the process adopted by moissan in order to cause volatilized carbon, or carbon vapor, to condense in the form of crystalline diamonds was practically as follows: he placed pieces of pure carbon inside a very strong steel tube, such, for example, as would be formed by boring a short cylindrical hole in a piece of strong thick steel, and placing a small quantity of carbon inside the tube so formed. closing the open end of the tube by means of a tightly fitting screw plug, he volatilized the carbon inside the tube. the steel, tube, and plug formed an electric furnace, for, as soon as he passed an electric current through it, the temperature at once became high enough to volatilize the carbon. under these circumstances the carbon vapor was subjected to great pressure owing to the limited space in which it was liberated. as soon as this mass of dense vapor had been formed, he seized the steel tube with a pair of furnace tongs, and plunged it below the surface of cold water in a bucket. of course, as the hot tube suddenly chilled, there was a great shrinking in the walls of the furnace, so that the already compressed carbon vapor was subjected to a still greater pressure which possibly liquified it. of that, however, we cannot speak definitely. this, however, can safely be asserted, that when the tube was broken open a confused mass of small crystals was found inside, some of which, on examination with the microscope, were found to consist of small crystals of two forms of diamonds, namely, the black diamond, or carbonado, and the regular crystallized diamond. moissan made a great number of experiments for producing diamonds in this way, and succeeded in forming some very beautiful, though microscopic, diamonds. what may be said to characterize especially moissan's experiments was the comparatively great number of diamonds, so small as to be scarcely distinguishable under the microscope. the high temperature to which the materials inside the tube were exposed resulted in the production of numerous minute crystals of different minerals. in order to get rid of as many of these as possible moissan adopted the plan of subjecting the material to the action of powerful solvents, such as sulphuric acid, aqua regia, or a mixture of sulphuric and nitric acid, and hydrofluoric acid. these acids destroyed most of the minute crystals of other minerals, but left the minute crystals of diamonds unaffected. now it will be observed that the theory proposed by prof. carvill lewis as to the probable origin of the diamonds of the kimberly mines bears a wonderfully close resemblance to the method adopted by moissan for the production of artificial diamonds, since it supposes the diamonds to have been formed by the sudden cooling or chilling within the pipe of various molten materials brought up from great depths by the volcanic forces. if this be true, then besides the comparatively large crystallized and perfect diamonds found in the blue ground of the kimberly mines, there should also be found large quantities of microscopic diamonds, just as are found in moissan's electric furnaces, in which he produced artificial diamonds. moissan, considering this, obtained a specimen of the blue ground from the kimberly diamond pipe and on subjecting it to the action of the different solvents before named, found in the mass that was left undissolved a great number of microscopic diamonds. it would seem, therefore, that there is no reasonable doubt but that the kimberly diamond fields had their diamonds produced by the sudden chilling in the volcanic pipes of molten materials brought from great depths by the force of volcanic eruption. chapter xxxvii the fabled continent of atlantis besides the sudden changes of level that frequently occur during earthquake shocks there are gradual changes of level that take place very slowly throughout long periods of time. these are believed to be due to the warpings produced by the cooling of an originally highly heated globe. it is not true, therefore, that the earth's surface is fixed, or that its land and water areas remain always the same. on the contrary, what is land at one time is water at another time, and so, too, water areas may become changed into land areas. for the most part these changes go on so slowly as not to be noticeable in an ordinary lifetime. indeed, in some cases, they are so extremely gradual that methuselah himself might have gone to his grave in ignorance of their progress. let us briefly note a few well-known gradual changes of level. one of the most extensive of these is the sinking of an immense area, over , miles in diameter, that covers a large part of the bed or floor of the pacific ocean. it is an easy matter to observe the gradual changes of level on the coasts, since the old water line can be at once found, but it is very difficult to detect such changes in the bed of the ocean, hidden as it is by a covering of water. yet many things that seem impossible to the uninitiated are readily solved by those familiar with physical science. little signs, meaningless to others, are easily read, and these prove beyond doubt the gradual sinking of the ocean's bed. it was once believed that the coral polyps or animalculæ from the hard, bony skeletons of which coral reefs are formed, could live at the greatest depths of the ocean. these minute animals were, therefore, generally credited with filling up the deep ocean, in certain places, and converting it into dry land, and poetic philosophers were pleased to point to their indefatigable labors as an object lesson to the slothful. but these charming, though fallacious, ideas were rudely overthrown by the sounding line and the drag-net. it had long been known that pieces of coral rock were brought up by dredging apparatus from the bottom of the ocean at all depths, but it was eventually shown that such pieces of coral rock never contained living animalculæ, when brought from water at greater depths than from to feet. it puzzled scientific men no little at first to explain this apparent inconsistency. if the coral polyp could not live in water at greater depths than from to feet, how could the presence of coral rock at a depth of thousands of feet be explained? happily, however, this problem was solved by the great naturalist, charles darwin, who showed that coral islands can only be formed in parts of the ocean whose beds are sinking at the same gradual rate at which the coral rock is being deposited. the presence, therefore, of coral islands on the bed of the pacific, as well as along parts of its coasts, are, to scientific men, as good indications of its gradual sinking as if such facts had been written in the clearest language. but there are other instances of gradual changes of level besides the bed of the pacific. about miles along the coast of greenland, from disco bay, near lat. ° n., south to the firth of igaliko, lat. ° ' n., the bed of the ocean has been slowly sinking through years. old buildings and islands have been covered by the waters, so that fishermen have been compelled to provide new poles for their boats. as sir charles lyell remarks: "in one place the moravian settlers have been obliged more than once to move inland the poles upon which their large boats are set, and the old poles still remain beneath the water as silent witnesses of the change." besides these gradual changes of level there are many others, but only one more need be cited: the gradual movements of the coasts of north america between labrador and new jersey that are rising in some places, and sinking in other places. the evidences of these gradual changes of level are sometimes of such a character that he who runs may read them. one of the most interesting is, perhaps, that of the old roman temple of jupiter serapis, at pozzuli, on the borders of the mediterranean. this temple, when completed, was feet in length and feet in width. its roof was supported by forty-six columns, each forty-two feet in height, and five feet in diameter. only three of these columns are now standing. they give, however, unquestionable evidence of having been submerged for about half their height. nor, indeed, is the evidence wanting that this submergence continued a considerable time; for, while the lower twelve feet of the columns remain smooth and unaffected, yet, for a distance of nine feet above this portion, they have been perforated by various stone-boring mollusks of a species still living in the mediterranean. this witnesses that the columns, when submerged, were buried in mud for twelve feet, and surrounded by water nine feet deep. according to dana, the pavement of the temple is still under water. the fact that another pavement exists below it shows that these changes of level had occurred before the temple was deserted by the romans. it appears, that, prior to , a gradual sinking of this part of the coast had been going on, but that since then there has ensued a gradual rising. the evidences of these gradual changes of level in the land and water surfaces of the earth cannot be doubted by even the most skeptical. again and again has the dry land disappeared below the surface of the waters of the ocean. again and again, the ocean's bed has been raised to the surface and been converted into dry land. suppose we attempt to follow one of the latter movements. we will imagine an extensive area to have slowly appeared above the ocean. in due process of time this land surface, which we will assume to have continental dimensions, gradually becomes covered with plant and animal life. if it remains above the water for a sufficient length of time, its simple plants and animals acquire more and more complex forms, so as to make it difficult to detect any traces of the original species from which they have descended, or, more correctly, ascended. moreover, where favorable conditions exist, the continent becomes peopled with men, who gradually advance from barbarism to semi-barbarism and eventually become a most highly civilized nation, sending to different parts of the world colonies, who carry with them the language and religious customs of the land of their birth. but, a sudden or paroxysmal change of level occurs. the highly developed and densely populated region is suddenly swept out of existence and completely covered by the waters of the ocean until, in a few thousand years, all traces of its existence have so completely disappeared that but few, if any, can be found willing to acknowledge it ever had an existence. such, it is claimed, was the fate of the fabled continent of atlantis. it will, therefore, be interesting to endeavor briefly to review its past history and to read some of the things that have been written about this part of the world, which appears in the opinion of some of the ancients to have actually existed. references to atlantis have been made by various early writers. solon, the great athenian lawgiver, who flourished years b. c., began a description of this place in verse. this description was never completed. at a later date one of solon's descendants, plato, who lived about b. c., prepared a description of atlantis, giving in detail its location, the general character of its surface, a description of its principal city, and the civilization of its inhabitants, as well as a brief reference to its sudden destruction. in another place this record of plato will be given in full. it will suffice now to quote briefly what he says concerning its location. "there was an island situated in front of the straits which you call the columns of heracles (straits of gibraltar). the island was larger than libya and asia put together, and was the way to other islands, and from the island you might pass through the whole in the opposite continent, for this sea which is within the straits of heracles is only a harbor, having a narrow entrance, but that other is the real sea, and the surrounding land may most truly be called a continent. now, in the island of atlantis, there was a great and wonderful empire, which had ruled over the whole island and several others, as well as over part of the continents; and, besides these, they subjected the parts of libya within the columns of heracles as far as egypt, and of europe as far as tyrrhenia. the vast power, thus gathered into one, endeavored to subdue at one blow our country and yours, and the whole of the land which was within the straits, and then, solon, your country shone forth, in the excellence of her virtues and strength, among all mankind, for she was the first in courage and military skill, and was the leader of the hellenes. and when the rest fell off from her, being compelled to stand alone, after having undergone the very extremity of danger, she defeated and triumphed over the invaders, and preserved from slavery those who were not yet subjected, and freely liberated all the others who dwelt within the limits of heracles. "but afterwards, there occurred violent earthquakes and floods, and in a single day and night of rain, all your warlike men in a body sunk into the earth, and the island of atlantis in a like manner disappeared, and was sunk beneath the sea. and that is the reason why the sea in those parts is impassable and impenetrable, because there is such a quantity of shallow mud in the way; and this was caused by the subsidence of the island." ("plato's dialogues," ii, , timæus). but besides solon and plato there are other ancient writers who refer to the lost island of atlantis. Ælian, in his "varia historia," lib. iii, chap. xvii, states that theopompos, who flourished b. c., refers to an interview between midas, king of phrygia, and sielus, in which the latter speaks of a great continent larger than asia, europe, and libya together that existed in the atlantic. proclus quotes a statement from an ancient writer, who speaks about the islands of the sea beyond the pillars of hercules (straits of gibraltar). marcellus, in a book on the ethiopians, refers to seven islands in the atlantic whose inhabitants preserve legends of a greater island (possibly atlantis), that had dominion over the small islands. diodorus siculus asserts that the phoenicians discovered a large island in the atlantic beyond the pillars of hercules several days' sail from the coast of africa. homer, plutarch, and other ancient writers, refer to several islands in the atlantic situated several thousand stadia from the pillars of hercules. (a stadium was a greek measure of length equal to feet. it was equal to one-eighth of a roman mile, or roman feet.) ignatius donnelly, in his book, called "atlantis, the ante-diluvian world," claims that plato's description of atlantis which has generally been regarded as imaginary, was, on the contrary, historic; that the prehistoric continent of atlantis was the cradle of the human race; that here man reached his highest civilization; that atlantis was the site of the garden of eden, the gardens of the hesperides, the elysian fields, as well as olympus; that, under the forms of the gods and goddesses of the ancient greeks, the phoenicians, the hindoos, and the scandinavians, are related the stories of the kings, queens, and heroes of atlantis. much that has been claimed for the lost continent can hardly be regarded in any other light save that of imagination. for example, it has been asserted that it was from atlantis that the colonies were sent out that peopled the coast countries of the gulf of mexico, of parts of the valley of the mississippi, the basin of the amazon, the western coasts of south america, parts of europe, the shore lands of the mediterranean sea, the coasts of europe, including the caspian and the black seas, and even of parts of africa. it has also been asserted that this mighty nation of atlantis carried the worship of the sun to egypt, which was one of its first colonies, and, therefore, the civilization of egypt was but an offshoot of prehistoric atlantis. but it will be reasonably objected that, if such a mass of land ever existed in the north atlantic, some evidences should still be found on the bed of the ocean. even though great periods of time have elapsed since the disappearance of atlantis, some traces of its former existence should still remain on the floor of the ocean. are there any evidences of an old land mass on this part of the floor of the atlantic? the answer is unmistakable. deep-sea soundings show beyond question that there still exists in the north atlantic in the region where atlantis is said to have been located a submarine island, the summits of which appear above the waters in the azores and the canary islands. this submarine island has been traced southwest over the bed of the ocean for a distance of several thousand miles with a breadth of fully , miles. toward the south there is connected with it another submarine island, the summits of which reach above the surface in the islands of ascension, st. helena, and tristan d'acunha. but the testimony of the submarine islands extends further than this. according to a number of careful soundings it appears that the bed of these parts of the ocean, instead of being characterized by a comparatively level surface due to the gradual accumulation of silt, possesses, to a great extent, the peculiarly sculptured surfaces which are only produced by exposure for a long time to the atmosphere. other facts might be adduced to show that some time during the first appearance of man on the earth there was a large land mass connecting the eastern and western continents. these facts include the wonderful resemblances existing between the plants and animals of the eastern and western continents, the close resemblances of the myths and legends of the races of the eastern and western continents, as well as the identity of their religious ideas, and the close similarity of their language so far as relates to certain fundamental ideas. these facts all point unquestionably to the existence of some large land mass between the two continents, and to this extent to throw light on the probable existence of prehistoric atlantis. chapter xxxviii plato's account of atlantis the following is a translation of plato's record in full: critias. then listen, socrates, to a strange tale, which is, however, certainly true, as solon, who was the wisest of the seven sages, declared. he was a relative and great friend of my great-grandfather, dropidas, as he himself says in several of his poems, and dropidas told critias, my grandfather, who remembered, and told us, that there were of old great and marvellous actions of the athenians, which have passed into oblivion through time and the destruction of the human race--and one in particular, which was the greatest of them all, the recital of which will be a suitable testimony of our gratitude to you.... socrates. very good; and what is this ancient famous action of which critias spoke, not as a mere legend, but as a veritable action of the athenian state, which solon recounted? critias. i will tell an old-world story which i heard from an aged man; for critias was, as he said, at that time nearly ninety-years of age, and i was about ten years of age. now the day was that day of the apaturia which is called the registration of youth; at which, according to custom, our parents gave prizes for recitations, and the poems of several poets were recited by us boys, and many of us sung the poems of solon, which were new at the time. one of our tribe, either because this was his real opinion, or because he thought that he would please critias, said that, in his judgment, solon was not only the wisest of men but the noblest of poets. the old man, i well remember, brightened up at this, and said smiling: "yes, amynander, if solon had only, like other poets, made poetry the business of his life, and had completed the tale which he brought with him from egypt, and had not been compelled, by reason of the factions and troubles which he found stirring in this country when he came home, to attend to other matters, in my opinion, he would have been as famous as homer, or hesiod, or any poet." "and what was that poem about, critias?" said the person who addressed him. "about the greatest action which the athenians ever did, and which ought to have been most famous, but which, through the lapse of time and the destruction of the actors, has not come down to us." "tell us," said the other, "the whole story, and how and from whom solon heard this veritable tradition." he replied: "at the head of the egyptian delta, where the river nile divides, there is a certain district which is called the district of sais, and the great city of the district is also called sais, and is the city from which amasis the king was sprung. and the citizens have a deity who is their foundress: she is called in the egyptian tongue neith, which is asserted by them to be the same whom the hellenes called athene. now, the citizens of this city are great lovers of the athenians, and say that they are in some way related to them. thither came solon, who was received by them with great honor; and he asked the priests, who were most skilful in such matters, about antiquity, and made the discovery that neither he nor any other hellene knew anything worth mentioning about the times of old. "on one occasion, when he was drawing them on to speak of antiquity, he began to tell about the most ancient things in our part of the world--about phoroneus, who is called 'the first,' and about niobe; and, after the deluge, to tell of the lives of deucalian and pyrrha; and he traced the genealogy of their descendants, and attempted to reckon how many years old were the events of which he was speaking, and to give the dates. thereupon, one of the priests, who was of very great age, said: 'o solon, solon, you hellenes are but children, and there is never an old man who is an hellene.' solon, hearing this, said, 'what do you mean?' 'i mean to say,' he replied, 'that in mind you are all young; there is no old opinion handed down among you by ancient traditions, nor any science which is hoary with age. and i will tell you the reason of this: there have been, and there will be again, many destructions of mankind arising out of many causes. "'there is a story which even you have preserved, that once upon a time phaëthon, the son of helios, having yoked the steeds in his father's chariot, because he was not able to drive them in the path of his father, burnt up all that was upon the earth, and was himself destroyed by a thunder-bolt. now, this has the form of a myth, but really signifies a declination of the bodies moving around the earth, and in the heavens, and a great conflagration of things upon the earth recurring at long intervals of time: when this happens, those who live upon the mountains and in dry and lofty places are more liable to destruction than those who dwell by rivers or on the sea-shore; and from this calamity the nile, who is our never-failing savior, saves and delivers us. "'when, on the other hand, the gods purge the earth with a deluge of water, among you herdsmen and shepherds on the mountains are the survivors, whereas those of you who live in cities are carried by the rivers into the sea; but in this country neither at that time nor at any other does the water come up from below, for which reason the things preserved here are said to be the oldest. the fact is, that wherever the extremity of winter frost or of summer sun does not prevent, the human race is always increasing at times, and at other times diminishing in numbers. and whatever happened either in your country or in ours, or in any other regions of which we are informed--if any action which is noble or great, or in any other way remarkable has taken place, all that has been written down of old, and is preserved in our temples; whereas you and other nations are just being provided with letters and the other things which states require; and then, at the usual period, the stream from heaven descends like a pestilence, and leaves only those of you who are destitute of letters and education; and thus you have to begin all over again as children, and know nothing of what happened in ancient times, either among us or among yourselves. "'as for those genealogies of yours which you have recounted to us, solon, they are no better than the tales of children; for, in the first place, you remember one deluge only, whereas there were many of them, and, in the next place, you do not know that there dwelt in your land the fairest and noblest race of men which ever lived, of whom you and your whole city are but a seed or remnant. and this was unknown to you, because for many generations the survivors of that destruction died and made no sign. for there was a time, solon, before that great deluge of all, when the city which now is athens, was first in war, and was preëminent for the excellence of her laws, and is said to have performed the noblest deeds, and to have had the fairest constitution of any of which tradition tells, under the face of heaven.' "solon marvelled at this and earnestly requested the priest to inform him exactly and in order about these former citizens. 'you are welcome to hear about them, solon,' said the priest, 'both for your own sake and for that of the city; and, above all, for the sake of the goddess who is the common patron and protector and educator of both our cities. she founded your city a thousand years before ours, receiving from the earth and hephæstus the seed of your race, and then she founded ours, the constitution of which is set down in our sacred registers as , years old. as touching the citizens of , years ago, i will briefly inform you of their laws and of the noblest of their actions; and the exact particulars of the whole we will hereafter go through at our leisure in the sacred registers themselves. if you compare these very laws with your own, you will find that many of ours are the counterpart of yours, as they were in the olden time. "'in the first place, there is the caste of priests, which is separated from all the others; next there are the artificers, who exercise their several crafts by themselves, and without admixture of any other, and also there is the class of shepherds and that of hunters, as well as that of husbandmen; and you will observe, too, that the warriors in egypt are separated from all the other classes, and are commanded by the law only to engage in war. moreover, the weapons with which they are equipped are shields and spears, and this the goddess taught first among you, and then in asiatic countries, and we among the asiatics first adopted. "'then, as to wisdom, do you observe, what care the law took from the very first, searching out and comprehending the whole order of things down to prophecy and medicine (the latter with a view to health); and out of these divine elements drawing what was needful for human life, and adding every sort of knowledge which was connected with them. all this order and arrangement the goddess first imparted to you when establishing your city; and she chose the spot of earth in which you were born, because she saw that the happy temperament of the seasons in that land would produce the wisest of men. "'wherefore the goddess, who was a lover both of war and of wisdom, selected, and first of all settled that spot which was the most likely to produce men likest herself. and there you dwelt, having such laws as these and still better ones, and excelled all mankind in all virtue, as became the children and disciples of the gods. many great and wonderful deeds are recorded of your state in our histories; but one of them exceeds all the rest in greatness and valor; for these histories tell of a mighty power which was agressing wantonly against the whole of europe and asia, and to which your city put an end. "'this power came forth out of the atlantic ocean, for in those days the atlantic was navigable; and there was an island situated in front of the straits which you call the columns of heracles: the island was larger than libya and asia put together, and was the way to other islands, and from the island you might pass through the whole of the opposite continent which surrounded the true ocean; for this sea which is within the straits of heracles is only a harbor, having a narrow entrance, but that other is a real sea, and the surrounding land may be most truly called a continent. now, in the island of atlantis there was a great and wonderful empire, which had rule over the whole island and several others, as well as over parts of the continent; and, besides these, they subjected the parts of libya within the columns of heracles as far as egypt, and of europe as far as tyrrhenia. "'that vast power, thus gathered into one, endeavored to subdue at one blow our country and yours, and the whole of the land which was within the straits; and then, solon, your country shone forth, in the excellence of her virtue and strength, among all mankind, for she was the first in courage and military skill, and was the leader of the hellenes. and when the rest fell off from her, being compelled to stand alone, after having undergone the very extremity of danger, she defeated and triumphed over the invaders, and preserved from slavery those who were not yet subjected, and freely liberated all the others who dwelt within the limits of heracles. but afterward there occurred violent earthquakes and floods, and in a single day and night of rain all your warlike men in a body sunk into the earth, and the island of atlantis in like manner disappeared, and was sunk beneath the sea. and that is the reason why the sea in those parts is impassable and impenetrable, because there is such a quantity of shallow mud in the way; and this was caused by the subsidence of the island.' ('plato's dialogues,' ii, , timæus.)... "but in addition to the gods whom you have mentioned, i would specially invoke mnemosyne; for all the important part of what i have to tell is dependent on her favor, and if i can recollect and recite enough of what was said by the priests, and brought hither by solon, i doubt not that i shall satisfy the requirements of this theatre. to that task, then, i will at once address myself. "let me begin by observing first of all that nine thousand was the sum of years which had elapsed since the war which was said to have taken place between all those who dwelt outside the pillars of heracles and those who dwelt within them. this war i am now to describe. of the combatants on the one side the city of athens was reported to have been the ruler, and to have directed the contest; the combatants on the other side were led by the kings of the islands of atlantis, which, as i was saying, once had an extent greater than that of libya and asia; and, when afterwards sunk by an earthquake, became an impassable barrier of mud to voyagers sailing from hence to the ocean. the progress of the history will unfold the various tribes of barbarians and hellenes which then existed, as they successively appear on the scene; but i must begin by describing, first of all, the athenians as they were in that day, and their enemies who fought with them; and i shall have to tell of the power and form of government of both of them. let us give the precedence to athens.... "many great deluges have taken place during the nine thousand years, for that is the number of years which have elapsed since the time of which i am speaking; and in all the ages and changes of things there has never been any settlement of the earth flowing down from the mountains, as in other places, which is worth speaking of; it has always been carried round in a circle, and disappeared in the depths below. the consequence is that, in comparison with what then was, there are remaining in small islets only the bones of the wasted body, as they may be called, all the richer and softer parts of the soil having fallen away, and the mere skeleton of the country being left.... "and next, if i have not forgotten what i heard when i was a child, i will impart to you the character and origin of their adversaries; for friends should not keep their stories to themselves, but have them in common. yet, before proceeding further in the narrative, i ought to warn you that you must not be surprised, if you should hear hellenic names given to foreigners. i will tell you the reason of this: solon, who was intending to use the tale for his poem, made an investigation into the meaning of the names, and found that the early egyptians, in writing them down, had translated them into their own language, and he recovered the meaning of the several names and retranslated them, and copied them out again in our language. my great-grandfather, dropidas, had the original writing, which is still in my possession, and was carefully studied by me when i was a child. therefore, if you hear names such as are used in this country, you must not be surprised, for i have told you the reason of them. "the tale, which was of great length, began as follows: i have before remarked, in speaking of the allotments of the gods, that they distributed the whole earth into portions differing in extent, and made themselves temples and sacrifices. and poseidon, receiving for his lot the island of atlantis, begat children by a mortal woman, and settled them in a part of the island which i will proceed to describe. on the side toward the sea, and in the centre of the whole island, there was a plain which is said to have been the fairest of all plains, and very fertile. near the plain, and also in the centre of the island, at a distance of about fifty stadia, there was a mountain, not very high on any side. in this mountain there dwelt one of the earth-born primeval men of that country, whose name was evenor, and he had a wife named leucippe, and they had an only daughter, who was named cleito. "the maiden was growing up to womanhood when her father and mother died; poseidon fell in love with her, and had intercourse with her; and, breaking the ground, enclosed the hill in which she lived all around, making alternate zones of sea and land, larger and smaller, encircling one another; there were two of land and three of water, which he turned as with a lathe out of the centre of the island, equidistant every way, so that no man could get to the island, for ships and voyagers were not yet heard of. he himself, as he was a god, found no difficulty in making special arrangements for the centre island, bringing two streams of water under the earth, which he caused to ascend as springs, one of warm water and the other of cold, and making every variety of food to spring up abundantly in the earth. he also begat and brought up five pairs of male children, dividing the island of atlantis into ten portions; he gave to the first-born of the eldest pair his mother's dwelling and the surrounding allotment, which was the largest and best, and made him king over the rest; the others he made princes, and gave them rule over many men and a large territory. "he named them all: the eldest, who was king, he named atlas, and from him the whole island and the ocean received the name of atlantic. to his twin brother, who was born after him, and obtained as his lot the extremity of the island toward the pillars of heracles, as far as the country which is still called the region of gades in that part of the world, he gave the name which in the hellenic language is eumelus, in the language of the country which is named after him, gadeirus. of the second pair of twins, he called one ampheres and the other evæmon. to the third pair of twins he gave the name mneseus to the elder, and autochthon to the one who followed him. of the fourth pair of twins he called the elder elasippus and the younger mestor. and of the fifth pair he gave to the elder the name of azaes, and to the younger diaprepes. "all these and their descendants were the inhabitants and rulers of divers islands in the open sea; and also, as has been already said, they held sway in the other direction over the country within the pillars as far as egypt and tyrrhenia. now atlas had a numerous and honorable family, and his eldest branch always retained the kingdom, which the eldest son handed on to his eldest for many generations; and they had such an amount of wealth as was never before possessed by kings and potentates, and is not likely ever to be again, and they were furnished with everything which they could desire both in city and country. for, because of the greatness of their empire, many things were brought to them from foreign countries, and the island itself provided much of what was required by them for the uses of life. "in the first place, they dug out of the earth whatever was to be found there, mineral as well as metal, and that which is now only a name, and was then something more than a name--orichalcum--was dug out of the earth in many parts of the island, and, with the exception of gold, was esteemed the most precious of metals among the men of those days. there was an abundance of wood for carpenters' work, and sufficient maintenance for tame and wild animals. moreover, there were a great number of elephants in the island, and there was provision for animals of every kind, both for those who live in lakes and marshes and rivers, and also for those which live in mountains, and on plains, and therefore for the animal which is the largest and most voracious of them. "also whatever fragrant things there are in the earth, whether roots, or herbage, or woods, or distilling drops of flowers, or fruits, grew and thrived in that land; and again, the cultivated fruit of the earth, both the dry edible fruit and other species of food, which we call by the general name of legumes, and the fruits having a hard rind, affording drinks, and meats, and ointments, and good store of chestnuts and the like, which may be used to play with, and are fruits which spoil with keeping--and the pleasant kinds of dessert which console us after dinner, when we are full and tired of eating--all these that sacred island lying beneath the sun brought forth fair and wondrous in infinite abundance. "all these things they received from the earth, and they employed themselves in constructing their temples, and palaces, and harbors and docks; and they arranged the whole country in the following manner: first of all they bridged over the zones of sea which surrounded the ancient metropolis, and made a passage into and out of the royal palace; and then they began to build the palace in the habitation of the god and of their ancestors. this they continued to ornament in successive generations, every king surpassing the one who came before him to the utmost of his power, until they made the building a marvel to behold for size and for beauty. "and, beginning from the sea, they dug a canal three hundred feet in width and one hundred feet in depth, and fifty stadia in length, which they carried through to the outermost zone, making a passage from the sea up to this, which became a harbor, and leaving an opening sufficient to enable the largest vessels to find ingress. moreover, they divided the zones of land which parted the zones of sea, constructing bridges of such a width as would leave a passage for a single trireme to pass out of one into another, and roofed them over; and there was a way underneath for the ships, for the banks of the zones were raised considerably above the water. "now the largest of the zones into which a passage was cut from the sea was three stadia in breadth, and the zone of land which came next of equal breadth; but the next two, as well a zone of water as of land, were two stadia, and the one which surrounded the central island was a stadium only in width. the island in which the palace was situated had a diameter of five stadia. this, and the zones and the bridge, which was the sixth part of a stadium in width, they surrounded by a stone wall, on either side placing towers, and gates on the bridges where the sea passed in. the stone which was used in the work they quarried from underneath the centre island and from underneath the zones, on the outer as well as the inner side. one kind of stone was white, another black, and a third red; as they quarried, they at the same time hollowed out decks, double within, having roofs formed out of the native rock. "some of their buildings were simple, but in others they put together different stones, which they intermingled for the sake of ornament, to be a natural source of delight. the entire circuit of the wall which went around the outermost one they covered with a coating of brass, and the circuit of the next wall they coated with tin, and the third, which encompassed the citadel, flashed with the red light of orichalcum. the palace in the interior of the citadel was constructed in this wise: in the centre was a holy temple, dedicated to cleito and poseidon, which remained inaccessible, and was surrounded by an enclosure of gold; this was the spot in which was originally begotten the race of ten princes, and thither they annually brought the fruits of the earth in their season from all the ten portions, and performed sacrifices to each of them. "here, too, was poseidon's own temple, of a stadium in length and half a stadium in width, and of a proportionate height, having a sort of barbaric splendor. all the outside of the temple, with the exception of the pinnacles, they covered with silver, and the pinnacles with gold. in the interior of the temple the roof was of ivory, adorned everywhere with gold and silver and orichalcum; all the other parts of the walls and pillars and floor they lined with orichalcum. in the temple they placed statues of gold: there was the god himself standing in a chariot--the charioteer of six winged horses--and of such a size that he touched the roof of the building with his head; around him were a hundred nereids riding on dolphins, for such was thought to be the number of them in that day. "there were also in the interior of the temple other images which had been dedicated by private individuals. and around the temple, on the outside, were placed statues of gold of all the ten kings and of their wives; and there were many other great offerings, both of kings and of private individuals, coming both from the city itself and the foreign cities over which they held sway. there was an altar, too, which in size and workmanship corresponded to the rest of the work, and there were palaces in like manner which answered to the greatness of the kingdom and the glory of the temple. "in the next place, they used fountains both of gold and hot springs. these were very abundant, and both kinds wonderfully adapted to use by reason of the sweetness and excellence of their waters. they constructed buildings about them, and planted suitable trees; also cisterns, some open to the heaven, others which they roofed over, to be used in winter as warm baths: there were the king's baths, and the baths of private persons, which were kept apart; also separate baths for women, and others again for horses and cattle, and to them they gave as much adornment as was suitable for them. the water which ran off they carried, some to the grove of poseidon, where were growing all manner of trees of wonderful height and beauty, owing to the excellence of the soil; the remainder was conveyed by aqueducts which passed over the bridges to the outer circles: and there were many temples built and dedicated to many gods; also gardens and places of exercise, some for men, and some set apart for horses, in both of the two islands formed by the zones; and in the centre of the larger of the two, there was a racecourse of a stadium in width, and in length allowed to extend all round the island, for horses to race in. "also there were guard-houses at intervals for the body-guard, the more trusted of whom had their duties appointed to them in the lesser zone, which was nearer the acropolis; while the most trusted of all had houses given them within the citadel, and about the persons of the kings. the docks were full of triremes and naval stores, and all things were quite ready for use. enough of the plan of the royal palace. crossing the outer harbors, which were three in number, you would come to a wall which began at the sea and went all round; this was everywhere distant fifty stadia from the largest zone and harbor, and enclosed the whole, meeting at the mouth of the channel toward the sea. "the entire area was densely crowded with habitations; and the canal and the largest of the harbors were full of vessels, and merchants coming from all parts, who, from their numbers, kept up a multitudinous sound of human voices and din of all sorts, night and day. i have repeated his descriptions of the city and the parts about the ancient palace nearly as he gave them, and now i must endeavor to describe the nature and arrangement of the rest of the country. the whole country was described as being very lofty and precipitous on the side of the sea, but the country immediately about and surrounding the city was a level plain, itself surrounded by mountains which descended toward the sea; it was smooth and even, but of an oblong shape, extending in one direction three thousand stadia, and going up the country from the sea through the centre of the island two thousand stadia; the whole region of the island lies toward the south, and is sheltered from the north. "the surrounding mountains were celebrated for their number and size and beauty, in which they exceeded all that are now to be seen anywhere; having in them also many wealthy inhabited villages, and rivers and lakes, and meadows supplying food enough for every animal, wild or tame, and wood of various sorts, abundant for every kind of work. i will now describe the plain, which had been cultivated during many ages by many generations of kings. it was rectangular, and for the most part straight and oblong; and what it wanted of the straight line followed the line of the circular ditch. the depth and width and length of this ditch were incredible, and gave the impression that such a work, in addition to so many other works, could hardly have been wrought by the hand of man. but i must say what i have heard. "it was excavated to the depth of a hundred feet, and its breadth was a stadium everywhere; it was carried round the whole of the plain, and was ten thousand stadia in length. it received the streams which came down the mountains, and winding round the plain, and touching the city at various points, was there let off into the sea. from above, likewise, straight canals of a hundred feet in width were cut in the plain, and again let off into the ditch, toward the sea. these canals were at intervals of a hundred stadia, and by them they brought down the wood from the mountains to the city, and conveyed the fruits of the earth in ships, cutting transverse passages from one canal into another, and to the city. twice in the year they gathered the fruits of the earth--in winter having the benefit of the rains, and in summer introducing the water of the canals. as to the population, each of the lots in the plain had an appointed chief of men who were fit for military service, and the size of the lot was to be a square of ten stadia each way, and the total number of all the lots was sixty thousand. "and of the inhabitants, of the mountains and of the rest of the country there was also a vast multitude having leaders, to whom they were assigned according to their dwellings and villages. the leader was required to furnish for the wars the sixth portion of a war-chariot, so as to make up a total of ten thousand chariots; also two horses and riders upon them, and a light chariot without a seat, accompanied by a fighting man on foot carrying a small shield, and having a charioteer mounted to guide the horses; also, he was bound to furnish two heavy-armed men, two archers, two slingers, three stone-shooters, and three javelin men, who were skirmishers, and four sailors, to make up a complement of twelve hundred ships. such was the order of war in the royal city. "that of the other nine governments was different in each of them, and would be wearisome to narrate. as to offices and honors the following was the arrangement from the first: each of the ten kings, in his own division and in his own city, had the absolute control of the citizens, and in many cases, of the laws, punishing and slaying whomsoever he would. "now the relations of their governments to one another were regulated by the injunctions of poseidon as the law had handed them down. these were inscribed by the first men on a column of orichalcum, which was situated in the middle of the island, at the temple of poseidon, whither the people were gathered together every fifth and sixth years alternately, thus giving equal honor to the odd and to the even number. and when they were gathered together they consulted about public affairs, and inquired if any one had transgressed in anything, and passed judgment on him accordingly--and before they passed judgment they gave their pledges to one another in this wise: "there were bulls who had the range of the temple of poseidon; and the ten who were left alone in the temple, after they had offered prayers to the gods that they might take the sacrifices which were acceptable to them, hunted the bulls without weapons, but with staves and nooses; and the bull which they caught they led up to the column. the victim was then struck on the head by them, and slain over the sacred inscription. now on the column, besides the law, there was inscribed an oath invoking mighty curses on the disobedient. when, therefore, after offering sacrifices according to their customs, they had burnt the limbs of the bull, they mingled a cup and cast in a clot of blood for each of them. the rest of the victim they took to the fire, after having made a purification of the column all round. "they then drew from the cup in golden vessels, and, pouring a libation on the fire, they swore that they would judge according to the laws on the column, and would punish any one who had previously transgressed, and that for the future they would not, if they could help, transgress any of the inscriptions, and would not command, or obey any ruler who commanded them, to act otherwise than according to the laws of their father poseidon. "this was the prayer which each of them offered up for himself and for his family, at the same time drinking, and dedicating the vessel in the temple of the god; and, after spending some necessary time at supper, when darkness came on and the fire about the sacrifice was cool, all of them put on most beautiful azure robes, and, sitting on the ground at night near the embers of the sacrifices on which they had sworn, and extinguishing all the fires about the temple, they received and gave judgment, if any of them had any accusation to bring against any one; and, when they had given judgment, at daybreak they wrote down their sentences on a golden tablet, and deposited them as memorials with their robes. "there were many special laws which the several kings had inscribed about the temple, but the most important was the following: that they were not to take up arms against one another, and they were all to come to the rescue, if any one in any city attempted to overthrow the royal house. like their ancestors, they were to deliberate in common about war and other matters, giving the supremacy to the family of atlas; and the king was not to have the power of life or death over any of his kinsmen, unless he had the assent of the majority of the ten kings. "such was the vast power which the god settled in the lost island of atlantis; and this he afterward directed against our land on the following pretext, as traditions tell. for many generations, as long as the divine nature lasted in them, they were obedient to the laws, and well-affectioned toward the gods, who were their kinsmen, for they possessed true and in every way great spirits, practicing gentleness and wisdom in the various chances of life, and in their intercourse with one another. "they despised everything but virtue, not caring for their present state of life, and thinking lightly on the possession of gold, and other property, which seemed only a burden to them; neither were they intoxicated by luxury, nor did wealth deprive them of their self-control; but they were sober, and saw clearly that all these goods are increased by virtuous friendship with one another, and that by excessive zeal for them and honor of them, the good of them is lost, and friendship perishes with them. "by such reflections, and by the continuance in them of a divine nature, all that which we have described waxed and increased in them; but when this divine portion began to fade away in them, and became diluted too often, and with too much of the mortal admixture, and the human nature got the upper hand, then, they being unable to bear their fortune, became unseemly, and to him who had an eye to see, they began to appear base, and had lost the fairest of their precious gifts; but to those who had no eye to see the true happiness they still appeared glorious and blessed at the very time when they were filled with unrighteous avarice and power. zeus, the god of gods, who rules with law, and is able to see into such things, perceiving that an honorable race was in a most wretched state, and wanting to inflict punishment on them, that they might be chastened and improved, collected all the gods into his most holy habitation, which, being placed in the centre of the world, sees all things that partake of generations. and when he had called them together, he spake as follows:" the story abruptly ends here, for plato left no further record. chapter xxxix nature's warning of coming earthquakes that there are signs of coming earthquakes which might be read by man, had he sufficient knowledge, there would seem to be but little doubt. these phenomena follow natural laws so that the approach of an earthquake must necessarily be in a definite order both as regards the phenomena which precede as well as those which follow it. there should, therefore, be signs that would enable one to predict its coming, although it must be acknowledged that these signs, so far as we actually know, are indistinct. it may seem to the unthinking and unobservant that the awful catastrophe of an earthquake comes entirely unheralded; that, apparently, it is not until the earth's surface begins to rock to and fro under the mighty forces that are causing destruction that its presence can be known. there are, however, many reasons for believing that in, perhaps, the greatest number of cases, it might have been foreseen, if greater attention had been given to the slight indications of its probable approach a short time before its occurrence. it is evident that the conditions of great pressure or stress in the earth's crust which finally result in a disastrous earthquake have been slowly accumulating for a long time, and that when the pressure at last reaches a point where the crust has to yield or slip, the ground is suddenly crushed and tossed to and fro while vast fissures and chasms are produced in the subterranean regions. at those points of the earth immediately above or in the neighborhood of such regions it is possible that there are many signs of the coming quake; and, although indistinguishable by our duller senses, are readily appreciated by the more highly developed senses of the lower animals. indeed, had we accustomed ourselves to reading the various indications of nature as the lower animals have, we, too, might be able to read these warnings of the coming earthquake. at great distances from the place where the earthquake starts there would necessarily be a better opportunity for predicting its approach. as already stated, what is called an earthquake does not consist of a single shaking of the ground, but of a highly complex series of shakings. according to mallet, the following waves start at the same time from the place of origin of an earthquake, when located on the bed of an ocean; i. e., an earth sound wave and a earth wave constituting the earth's shake; a sound wave through the ocean, another through the air; a sea wave called by him a forced sea wave, and finally the great sea wave. these waves reach a distant point in the following order: the sound wave through the earth and the great earthquake or shake which produces the damage. then a smaller sea wave called the forced sea wave. this is followed almost immediately by the sound wave through the sea. next come the air sound wave and finally the great sea wave; which, rushing in on the shore, sweeps nearly everything before it. in other words, the disturbances produced by the great earthquake follow in this order of sequence. if, therefore, the great earthquake wave proper transmitted through the earth should for any reason be delayed in reaching a distant place, the great sound waves should be able to give warning of the coming disturbances. again, as we have already seen, the earthquake wave is preceded by a number of preliminary tremors, and is followed by a number of after tremors or _earthquake echoes_. since, therefore, the preliminary waves reach a place first, it would seem that the approach of an earthquake must be heralded by the preliminary tremors. these, perhaps, at least in part, enable the lower animals to detect its coming. again, in almost all instances there are a number of preliminary shocks that precede the great earthquake shock. some of these preliminary shocks continue at intervals for several days or even longer. sometimes, indeed, these subterranean sounds fail to be followed by earthquakes. milne thinks that these sounds are caused by the preliminary tremors which precede the principal shock of the earthquake and that they reach the place first. here again then it is evident that, were we able to interpret properly these sounds, we would probably be able to foretell the coming quake with a fair degree of certainty. there would appear to be no reasonable doubt that in some manner which we have not yet been able to discover, but probably along some of the lines indicated above, animals are capable of recognizing a coming earthquake. long before the coming of the catastrophe they are said to exhibit extreme terror, and in many cases appear to seek the companionship of man, as if for protection. that the senses of smell and hearing are far more acute in the lower animals than in man no one can reasonably doubt. the manner in which a trained dog can follow a scent, for a long time after the animal or thing producing it has passed, far exceeds the power of scent possessed by man, and it is more than likely that this same power is possessed by all animals who live upon or prey upon other animals. it is probable that faintly odorous vapors or gases escape from the crust shortly before the great shock occurs, and that these faint odors are warnings to the animals of the approaching calamity. the sense of hearing also is much more acute in the lower animals. daubeny is evidently of this belief, as will be seen from the following: "these gases and vapors (alluding to emanations given off from the ground during earthquakes) exert an influence on the barometer, which does appear to be indirectly affected by the earthquake. then, similar properties also may occasion that uneasiness which animals are said to evince before any such event. thus, according to the accounts of some writers, rats and mice leave their holes, alligators seek the dry land, quadrupeds snuff the ground, and manifest such signs of the impending calamity that in countries where earthquakes are common, the inhabitants take the alarm in consequence, and escape from their houses. it is right, however, to add, that more recent authorities dispute altogether the correctness of these statements." dutton doubts the ability of animals to foretell coming earthquake shocks. but that the lower animals do exhibit signs of fear at the approach of an earthquake has been repeatedly asserted by good observers. hamilton, who made a careful examination of the neighboring country during the great earthquake at calabria, asserts that horses and oxen during the shocks extended their legs widely in order to avoid being thrown down, "and that hogs, oxen, horses, and mules, and also geese, appeared to be painfully aware of the approach of the earthquake of calabria; and the neighing of a horse, the braying of an ass, or the cackling of a goose, even when he (hamilton) was making his survey (after the occurrence of the great earthquake shock), drove the people out of their temporary sheds in expectation of a shock." it is asserted that birds appear to be especially sensible to a coming earthquake shock. that geese will quit the water in which they were swimming before the earthquake and will not return to it. it is quite possible that these birds with their heads immersed in the water can hear the distant murmurings long before they become audible in the air. von hoff makes the following statement: "it has been remarked that at such times (immediately before the coming of an earthquake shock), domestic animals showed a decided uneasiness, dogs howled mournfully, horses neighed in an unusual manner, and poultry flew restlessly about. these latter phenomena might easily be produced by mephitic vapours, which often ascend to the surface of the earth before the breaking out of an earthquake." mallet states that there is abundant evidence that earthquake shocks, even when not of very great intensity, produce nausea in both men and women. this would seem natural, since, as everyone knows, until one is accustomed to sea-voyages, merely to be tossed to and fro by the motion of the waves results in the production of sea-sickness. it has been also noticed that during earthquakes fish which under ordinary circumstances live in the mud at the bottom of bodies of water come near to the surface and at such times can be caught in great numbers. mallet cites the following effects produced by earthquakes: "amongst the effects supposed to be produced by the earthquake on the atmosphere were reckoned tempestuous winds, thunder-storms, meteors, coldness of the air, severe winters, heavy rains, miasmata, producing diseases and affecting vegetation. a very remarkable instance of the latter is quoted, namely, that in peru, after the earthquake of , wheat and barley would not thrive at all, though formerly the country was remarkably favourable for them." sir charles lyell notes the following phenomena attending earthquakes: "irregularities in the seasons preceding or following the shocks; sudden gusts of wind, interrupted by dead calms; violent rains at unusual seasons, or in countries where, as a rule, they are almost unknown; a reddening of the sun's disk, and haziness in the air, often continued for months; an evolution of electric matter, or of inflammable gas from the soil, with sulphurous and mephitic vapours; noises underground, like the running of carriages, or the discharge of artillery, or distant thunder; animals uttering cries of distress, and evincing extraordinary alarm, being more sensitive than men to the slightest movement; a sensation like sea-sickness, and a dizziness in the head, experienced by men. these, and other phenomena, less connected with our present subject as geologists, have recurred again and again at distant ages, and in all parts of the globe." the end footnotes: [footnote : a point on the other side of the earth directly opposite a given point.] [footnote : a fracture of a stratum, or a general rock mass, with a relative displacement of the opposite sides of the break. the plane or fracture of a fault, known as the fault-plane, is seldom vertical. the higher side is called the heaved or upthrow side; the opposite side the thrown or downthrow side.] [footnote : _tectonic earthquake_. an earthquake due to the sudden slip of faulted strata.] [footnote : _i. e._, burnt out mountain, extinct volcano.] [footnote : _epicentre._ a point on the surface of the earth vertically above the point of origin of an earthquake, or the place where it starts.] transcriber's notes obvious printer errors have been silently corrected. some illustrations have been moved to paragraph breaks. page : kamehamoha could be a typo for kamehameha. page : changed "salter" to "saltier." (orig: another with water salter than the sea,) page : changed "ena" to "etna." (orig: during his time mt. ena had lost so much of its height) page : "eruption during the winter of - ," could be a typo for - or - . page : "mont pelée" could be a typo for "mount pelée." page : ° c." ( ° ' f.). could be a typo for ( . ° f.). page : changed one-eight to one-eighth. (orig: it was equal to one-eight of a roman mile) retained the following spelling variations: page : the largest volcano in iceland, the dyngjufköll, page : the largest volcano in iceland is dyngjufjoll. pages , , : geikie page : geicke pages , , : hindostan page : hindustan page : lucullis page : lucullus transcriber note text emphasis denoted as _italic_ and =small caps=. the journal of geology _january-february, ._ * * * * * on the pre-cambrian rocks of the british isles. during the last twenty years much has been written about the "pre-cambrian" rocks of the british isles. unfortunately when attention began to be sedulously given to the study of these ancient formations, the problems of metamorphism were still a hundred fold more obscure than they have since become; the aid of the microscope had not been seriously and systematically adopted for the investigation of the crystalline schists, and geologists generally were still under the belief that the broad structure of these schists could be treated like those of the sedimentary rocks, and be determined by rapid traverses of the ground. we have now painfully discovered that these older methods of observation were extremely crude, and that the work performed in accordance with them is now of little interest or value save as a historical warning to future generations of geologists. geological literature has meanwhile been burdened with numerous contributions which remain as a permanent incubus on our library shelves. it may serve a useful purpose at the present time in possibly aiding those who are engaged in the study of the oldest rocks of north america, if i place before them, as briefly as possible, the main facts which in my opinion have now been satisfactorily proved regarding the corresponding rocks of britain, and if i indicate at the same time some of the more probable inferences in those cases where the facts, at present known, do not warrant a definite conclusion. it is obvious that in any effort to establish that a group of rocks is older than the very base of the sedimentary fossiliferous formations, we must somewhere find that group emerging from under the bottom of these formations. until lithological characters are ascertained to be so distinctive and constant as to be comparable to fossil evidence for purposes of stratigraphical identification, we should not assume that detached areas of older rocks rising amid palæozoic, secondary or tertiary formations are pre-cambrian. we should, if possible, begin at the bottom of the palæozoic systems and work backward, tracing each successive system or group as these rise from under each other, until we arrive at what appears to be the oldest traceable within the region of observation. it is clear that in the present state of knowledge we have no satisfactory means of identifying such successive systems in widely separated countries. all that can be attempted in the meantime is to ascertain the special types in each region, and to point out their general resemblances or contrasts to those of other regions. it is better to avoid confusion by refraining from applying the stratigraphical names adopted for the oldest rocks of one region to those of another geographically remote, though we may hope that eventually it may be possible to work out the equivalence of these local names. in the british isles, by much the most important region for the study of the oldest rocks is to be found in the north-west highlands of scotland. the very basement strata of the cambrian system are there traceable for a distance of more than miles, reposing with a strong unconformability upon all rocks of older date. they consist of dolomitic shales with _olenellus_, resting upon a thick group of quartzites, full of annelid tubes. one of the most remarkable features of these ancient strata is the persistence of their component bands or zones which, though sometimes only a few feet thick, can be traced throughout the whole tract of country just referred to. for the study of the pre-cambrian rocks this is an important point, for we can be quite certain that even where fossil evidence locally fails, the same basement members of the cambrian system are persistent and lie directly upon the pre-cambrian series. _lewisian gneiss._ ever since the researches of murchison and nicol in the north-west of scotland, it has been known that two distinct systems of rock underlie the quartzites to which i have just alluded. murchison regarded the upper of these as of cambrian age, while he assigned the unconformable quartzites and limestones above it to the lower silurian period. but the recent discovery of the _olenellus_ zone intercalated conformably between the quartzites and the overlying limestones may be regarded as proving that all the rocks which underlie the quartzites and are separated from them by a strong unconformability must be pre-cambrian. it is thus established beyond any reasonable doubt that two great pre-cambrian systems of rock exist in the north-west of scotland. these two systems differ so entirely from each other that their respective areas can be defined with minute accuracy. the uppermost consists chiefly of dull reddish sandstones with conglomerates, and especially towards their base in rosshire, some bands of dark grey shale, the whole having a thickness of at least , or , feet, though as both the base and the top of the series are marked by strong unconformabilities, the whole original thickness of deposits is nowhere seen. as these rocks are well developed around loch torridon, they were named by nicol the torridon sandstone--a designation which has more recently been shortened into "torridonian." the lower system is mainly composed of various foliated rocks which may be embraced under the general term "gneiss." these masses present the usual characters of the so-called "fundamental complex", "urgebirge," or "archæan series" of other countries. the contrast between the thoroughly crystalline, gnarled, ancient-looking gneisses below, and the overlying, nearly horizontal torridonian conglomerates, sandstones, and shales, which are largely made out of their debris, is so striking that every observer feels persuaded that in any logical system of classification they can not be both placed in the same division of the geological record. they are certainly both pre-cambrian, but they must belong to widely separated eras, and must have been produced by entirely different processes. if it is proposed to regard the gneisses as "archæan," we must refuse to include the torridonian strata in the same section of pre-cambrian time. but so much uncertainty exists as to the application of this term archæan, examples are so multiplying wherein what was supposed to be the oldest and truly archæan rock is found to be intrusive in rocks that were taken to be of much younger date, and there are such slender grounds for correlating the so-called archæan rocks of one country with those of another, that i prefer for the present, at least, not to use the term at all. let me very briefly state some of the main characteristics of the two sharply contrasted rock-systems of the north-west of scotland. the oldest gneiss of that region was originally called "lewisian" by murchison, from its large development in the island of lewis, and i think it would be, for the present at least, an advantage to retain this geographical appellation. at first this "fundamental gneiss" was thought to be a comparatively simple formation, and the general impression probably was that it should be regarded as a metamorphic mass, produced mainly from the alterations of very ancient stratified rocks. its foliation-planes were believed to be those of original deposit which by terrestrial disturbance had been thrown into numerous plications and corrugated puckerings. but a detailed study of this primeval rock has revealed in it a far more complicated structure. the supposed bedding-planes have been ascertained to have nothing to do with sedimentary stratification, and the gneiss has been resolved into a complex series of eruptive rocks, varying from a highly basic to an acid type, and manifestly belonging to different times of extrusion. with the exception of one district, to which i shall immediately refer, no part of the whole region yet examined has revealed to the rigid scrutiny of my colleagues of the geological survey, any trace of rocks which can be regarded as probably of other than igneous origin. it is true that our researches have been hitherto confined to the mainland of scotland, the large area of the outer hebrides, which consists of similar gneisses, remaining to be explored. it is therefore possible that indisputable evidence of an ancient sedimentary series through which the gneiss was originally protruded, may yet be discovered in the unexplored islands. but taking the gneiss as at present known in sutherland and rosshire, we find it to be generally coarse in texture, rudely foliated, and passing sometimes into massive types in which foliation is either faintly developed or entirely absent. much of this gneiss is considerably more basic than the more typical rocks to which the term gneiss was formerly restricted. it consists of plagioclase felspar with pyroxene, hornblende, and magnetite, sometimes with blue opalescent quartz, and sometimes with black mica. these predominant minerals are segregated in different proportions in the different bands, some bands consisting mainly of pyroxene or hornblende, with little or no plagioclase, others chiefly of plagioclase, with small quantities of the ferro-magnesian minerals and quartz, others of plagioclase and quartz, others of magnetite. this separation of mineral constituents can hardly be attributed to mere mechanical deformation. it rather resembles the segregation layers which may be studied in intrusive sills and other deep-seated masses of eruptive material, and which are obviously due to a process of separation that went on while the igneous magma was still in a liquid or viscous condition. at the same time it is manifest that extensive dynamical changes have affected the rocks since the appearance of this original banded structure. there is further evidence that beside the original eruptive masses, which for want of any means of discriminating their relative dates of protrusion must in the meantime be regarded as belonging to one eruptive period, other portions of igneous material have been subsequently and at successive epochs, after the first mechanical deformations, injected into the body of the original gneiss. these consist of dykes of basalt and dolerite, followed by still more basic peridotites and picrites, and lastly by emanations from a distinctly acid magma in the form of granites. the oldest or doleritic dykes form a wonderful feature in the gneiss, from their abundance, persistence and uniformity of trend in a west-northwest direction. they have no parallel in british geology until we reach the crowded dykes of older tertiary time. throughout this remarkable complex of eruptive material, though its different portions present many features that may be compared with those of intrusive bosses and sheets belonging to later geological periods, there is no trace of any superficial volcanic manifestation. no tuffs or agglomerates or slaggy lavas have been detected, such as might serve to indicate the ejection of volcanic materials to the surface. all the phenomena of the lewisian gneiss point to the consolidation of successively protruded portions of eruptive material at some depth within the crust. nevertheless it may yet be possible to show that these deep seated masses have been injected into rocks of older date and of sedimentary origin, and that they have communicated with the surface in true volcanic eruptions. i have already alluded to one limited area where various rocks exist, distinctly different from the prevalent types in the lewisian gneiss. in the area which is traversed by the long valley of loch maree in western rosshire, there occur clay-slates, fine mica schists, graphitic schists, and saccharoid limestones. these rocks remind us of some of the prevalent members of a series of metamorphosed sediments. the minerals enclosed in the marbles are just such as might be expected in the metamorphic aureole of a granite boss, piercing limestone. but the relations of this group of rocks to the ordinary gneiss of the region are not quite so clear as could be desired, though they seem to point to these rocks being surrounded by and enclosed within the gneiss. the detailed field-work of the officers of the geological survey has made known the remarkable amount of mechanical deformation which the various rock-masses composing the lewisian gneiss have undergone. these rocks have been compressed, crushed, and drawn out, until what were originally massive crystalline protrusions have been converted into perfect schists. the dykes of dolerite have been transformed into hornblende-schists and the granitic pegmatites have been reduced to a kind of powder which has been rolled out so as to simulate the flow-structure of a lava. there is evidence that most, if not all, of this dynamical change was effected long before the deposition of the torridonian series, for the latter rests in nearly horizontal sheets, with a strong unconformability upon the crushed and sheared gneiss. _torridon sandstone._ this group of rocks covers only a limited area in the north-west of scotland, but it must once have spread over a far more extensive region. it reaches a thickness, as i have said, of , or , feet, and consists almost wholly of dull, purplish-red sandstones, often pebbly, and bands of conglomerate. dark grey shales, already alluded to as occurring towards the base of the series, are repeated also in the highest visible portion, and have yielded tracks of what seem to have been annelids and casts of nail-like bodies which may have been organic. i have said that the torridonian deposits which were classed by murchison as cambrian, have been proved by the discovery of the _olenellus_ zone in an unconformable position above them, to be of pre-cambrian age. except along the line of disturbance to which i shall immediately refer, these strata are quite unaltered. indeed, in general aspect they look as young as the old red sandstones with which hugh miller identified them. it is at first hard to believe that such flat undisturbed sandstones are of higher antiquity than the very oldest palæozoic strata which are so generally plicated and cleaved. the interval of time between the deposition of the torridon sandstone and of the overlying cambrian formations must have been of enormous duration, for the unconformability is so violent that the lowest cambrian strata, not only transgressively overspread all the torridonian horizons, but even lie here and there directly on the old gneiss, the whole of the intervening thick mass of sandstone having been there removed by previous denudation. at durness, in the north of sutherland, about feet of cambrian (possibly in part lower silurian) strata can be traced, the lower portion consisting of quartzites, the central and upper parts of various limestones, sometimes abundantly fossiliferous. nowhere else in the north of scotland can so thick a mass of early palæozoic rocks be seen. elsewhere the limestones have been in large measure replaced by a complex group of schistose rocks which rest upon the cambrian strata, and like them dip, generally at gentle angles, towards the east. it was the opinion of murchison, and was commonly admitted by geologists, that these overlying schists represented a thick group of sediments, which, originally deposited continuously after the limestones, had been subsequently altered into their present condition by regional metamorphism. they were variously named the "eastern schists," the "younger gneiss," the "gneissose and quartzose flagstones." nicol, who at first shared the general opinion regarding them, afterwards maintained that they did not belong to a later formation than the limestones, but were really only the old gneiss, brought up again from beneath by enormous dislocations and over-thrusts. we now know from the labors of professor lapworth and the officers of the geological survey, that murchison and nicol had each seized on an essential part of the problem, but that both of them had missed the true solution. murchison was in error in regarding his younger gneiss as a continuous sequence of altered sedimentary rocks conformably resting on the cambrian (or to use his terminology, lower-silurian) formations. but he sagaciously observed the coincidence of dip and strike between the schists and sedimentary rocks below them and inferred that this coincidence, traceable for many leagues, proved that the metamorphism which had given these schists their structure must have taken place after the deposition of the durness limestones. nicol, on the other hand, with great insight recognized that there was no continuous sequence above those limestones, but that masses of the old gneiss had been thrust over them by gigantic faults. but he failed to see that no mere faults would account for the coincidence between the structural lines just referred to in the cambrian strata, and in the overlying schists, and that the general tectonic structures and lithological characters of the eastern schists differed in many respects from those of the lewisian gneiss. the problems in tectonic geology presented by the complicated structures of the northwest of scotland have been ably worked out by the officers of the geological survey, to whose report in the _quarterly journal of the geological society_ for , i would refer for full details. it has been shown that, besides stupendous dislocations and horizontal displacements, the rocks have been cut into innumerable slices which have been driven over each other from the eastward, while at the same time there has been such a general shearing of the whole region that for many hundreds of square miles the original rock-structures have been entirely effaced, and have been replaced by new divisional planes, which, when they approach the underlying cambrian strata, are roughly parallel with the bedding planes of these strata. in this region, therefore, we have striking proofs of a stupendous post-cambrian regional metamorphism. but there is still much uncertainty regarding the geological age of the rocks which have been affected by it. there can be no doubt that large masses of the old gneiss, torn up from below, have been thrust bodily westward for many miles, and are now seen with their dykes and pegmatites resting on the durness limestones and quartzites. it is equally certain that in other districts huge slices of the torridon sandstones have been similarly treated. but where all trace of original structure has disappeared, we have, as yet, no means of definitely determining from what formation the present eastern schists have been produced. the ordinary gneissose and quartzose flagstones do not appear to me to be such rocks as could ever be manufactured by any chemical or mechanical process out of the average type of lewisian gneiss. i have long held the belief that they were originally sediments, but whether they represent altered torridon sandstone, or some clastic formations which may have followed the durness limestones, but which have been everywhere and entirely metamorphosed, remains for future discovery. for my present purpose, it is sufficient to observe that, in the meantime, as we can not be sure of the origin of most of the rocks, which, between the west coast and the line of the great glen, have been subjected to a gigantic post-cambrian regional metamorphism, it seems safest to exclude them from an enumeration of the pre-cambrian rocks of britain. _dalradian._ east of the line of great glen, which cuts the scottish highlands in two, another group of crystalline schistose rocks is largely developed. it consists mainly of what were undoubtedly originally sedimentary deposits, though they are now found in the form of quartzites, phyllites, graphitic schists, mica-schists, marbles, and various other foliated masses. with them are associated numerous eruptive rocks, both acid and basic, sometimes still massive and easily recognizable as intrusive, sometimes more or less distinctly foliated and passing into different gneisses, hornblende-schists, chloritic-schists, etc. though it is not always possible in such a series of metamorphic rocks to be certain of any real chronological order of succession, those of the highland tracts have now been mapped in detail over so wide an area, that we are probably justified in believing that a definite sequence can be established among them. these masses must be many thousand feet thick. their succession and association of materials are so unlike those of any of the known older palæozoic rocks of britain, that they can hardly be the metamorphosed equivalents of any strata which can be recognized in an unaltered condition in these islands. some traces of annelid casts have been found in the quartzites, but otherwise the whole series has remained entirely barren of organic remains. what then is the age of this important series? i must confess that in the meantime i can give no satisfactory answer to this question. i have proposed, for the sake of distinction and convenient reference, to call these rocks "dalradian." murchison supposed them to be a continuation of his durness quartzites, limestones, and "younger gneiss." his belief may still prove to be in some measure well founded. but at present we have no means of deciding whether the quartzites and limestones of the central highlands are the more altered equivalents of the undoubtedly cambrian strata of the north-west. it is possible that in the vast mass of metamorphosed rocks constituting the wide stretch of country from the northern headlands of aberdeen to the south-western promontories of argyllshire, there may be portions of the old lewisian gneiss, tracts of highly altered torridon sandstone, belts of true counterparts of the cambrian quartzites and limestones of durness, and, what should not be forgotten, considerable portions of some later sedimentary series which may have followed these limestones, but which, by the great dislocations already referred to, have disappeared from the north-west of scotland. we are gradually learning more of these rocks, as the detailed mapping of them by the geological survey advances, and when the ground on either side of the great glen is surveyed, it may be possible to speak with more certainty regarding their true geological relations. a glance at a geological map of the british isles will show that the metamorphic rocks of the south-western highlands of scotland are prolonged into the north of ireland, where they spread over a region many hundred square miles in extent. they retain there the same general character and present the same difficult problems as to their true stratigraphical relations. quite recently, however, a new light seems to have arisen upon these irish rocks. my colleagues on the irish branch of the geological survey have detected several detached areas of coarse gneisses, which in many respects resemble parts of the lewisian gneiss of north-west scotland. in some cases these areas lie amidst or close to "dalradian" rocks, but with that obstinacy, which so tries the patience of the field-geologist, they have persistently refused to disclose their true original position with regard to these. some fault, thrust-plane, tract of boulder-clay or stretch of bog is sure to intervene along the very junction-line where the desired sections might have been looked for. there can be little doubt that a strong unconformability exists between them. a close examination of the ridge of old gneiss in tyrone and fermanagh showed me that though the actual basement-beds of this dalradian series could not be seen resting on the coarse gneiss, the lithological character, and tectonic arrangement of this series are only explicable on the supposition of a complete discordance between it and the gneiss. as these two groups of rock have never been found in close proximity in scotland, and as the determination of the true age of the dalradian series is a question of such great stratigraphical importance in the general mapping of the united kingdom, i requested mr. a. mchenry, of the geological survey of ireland, to continue the tracing of the mutual boundaries of the old gneiss of the ox mountains and the dalradian series in county mayo. he informs me that he has found in that series a conglomerate full of blocks of the old gneiss, and resting in one locality apparently unconformably upon it. if this observation is confirmed it will finally set at rest the relative position of the coarse massive gneiss and some portion, at least, of the dalradian series. of course there is no absolute proof that the coarse gneisses of ireland are really the equivalents of the lewisian masses which they so closely resemble. but there is a strong presumption in favor of their identity. in england and wales many detached areas of rock have been claimed as pre-cambrian, and successive formations have been classified among them. i have already dealt in part with this question, and without attempting here to review the voluminous literature of the subject, i will content myself with stating briefly what seems to me to have been established on good evidence. there can not, i think, be now any doubt that small tracts of gneiss, quite comparable in lithological character to portions of the lewisian rocks of the north-west of scotland, rise to the surface in a few places in england and wales. in the heart of anglesey, for example, a tract of such rocks presents some striking external or scenic resemblance to the characteristic types of ground where the oldest gneiss forms the surface in scotland and the west of ireland. in the malvern hills another small knob of somewhat similar material is obviously far more ancient than the cambrian rocks of that locality. there may possibly be still some further exposures of similar rocks in the south of england, as for instance in southern cornwall. in anglesey a series of schists, quartzites and limestones has been included by mr. j. f. blake with the coarse gneiss above referred to, and a thick higher group of slates in what he terms the "monian" system. these schists, quartzites and limestones present a close resemblance to the dalradian series of scotland and ireland, and the quartzites, like those of the highlands, contain worm-burrows. the coarse gneiss, as i have said, may be compared in general character with parts of the lewisian rocks, so that we seem to have here, as in ireland, two groups of schistose rocks, and both of these must be much older than the unaltered cambrian strata which lie above them. along the eastern borders of wales, there is an interrupted ridge of igneous rocks which were originally supposed to have broken through the older palæozoic formations, but which now, owing mainly to the labors of dr. callaway and professor lapworth, are shown to be older than the base of the cambrian system. these rocks consist of spherulitic and perlitic felsites, with volcanic breccias and tuffs. they are undoubtedly older than the _olenellus_ zone. though the evidence is not quite satisfactory, they may not impossibly lie at the base of a vast mass of sedimentary rocks forming the ridge of the longmynd. in that case the whole of the longmynd succession with the volcanic group at its base must be pre-cambrian and lie unconformably below the _olenellus_ zone. dr. callaway has proposed the name "_uriconian_" for this volcanic group, while the sedimentary series has been termed "_longmyndian_." on the supposition that the unconformability is established, there would here be a vast mass of stratified and partly erupted material forming a pre-cambrian formation. whether in that case any portion of this english series is the equivalent of the torridonian rocks of scotland remains to be determined. the northwestern part of the longmynd ridge is made of red sandstones and conglomerates, which certainly resemble the torridonian rocks of ross and sutherland. at the base of the cambrian rocks in wales, dr. hicks has described a marked volcanic series under the name of "pebidian," which he claims as pre-cambrian, alleging that it is separated from the cambrian system by an unconformability, and a band of conglomerates. i have carefully studied the evidence on this ground, and have come to the conclusion that there is no unconformability at the line in question, but that the ordinary cambrian strata graduate downwards into the volcanic group and can not be disjoined from it. i therefore regard the so-called "pebidian" as merely marking the duration of a volcanic period in early cambrian time. it will thus be seen that according to my view the unmistakably pre-cambrian rocks of britain consist of, first and oldest, the lewisian gneiss; second, the torridonian sandstones and conglomerates. the uriconian and longmyndian formations may prove to be in part or in whole equivalents of the torridonian. the dalradian rocks have not yet had their position determined. they may possibly mark a distinct pre-cambrian series, but it seems quite as probable that they are only a metamorphic complex in which archæan, torridonian and cambrian, or even lower silurian rocks are included. =sir archibald geikie=, director-general of the geological survey of great britain and ireland. are there traces of glacial man in the trenton gravels? in a paper published in _science_, nov. . , i undertook to study the evidence relating to paleolithic man in the eastern united states from a new point of view,--that furnished by certain recently acquired knowledge of the contents of quarries and shops where modern aboriginal flaked implements were made. it was shown that all rudely flaked forms could be sufficiently accounted for without the necessity of assuming a very rude state of culture, and that any people, paleolithic or neolithic, would in roughing out blades--the principal product of the flaking process--produce precisely these forms and in great numbers as refuse. it further appeared that the finding of these objects in sporadic cases in glacial gravels or in any formation whatsoever, could not be considered as proving or tending to establish the existence of a particular grade of stone-age culture for the region in which the formation occurs, since they may as readily pertain to a neolithic as to a paleolithic status. it was conclusively shown that no worked stone that can with reasonable safety be called an implement has been reported from the gravels, and that it is therefore clearly useless, not to say unscientific, to go on enlarging upon the evidence of an american paleolithic period and multiplying theoretic details of its culture. i now propose to review briefly the question of the age of our so-called paleolithic implements, the questions of the _grade_ of a given feature of culture and of the _age_ or chronologic place of that culture being very properly treated separately, as they depend for their support upon distinct classes of evidence. during the past summer, , certain important items of new evidence have been discovered bearing upon the question of the occurrence or non-occurrence of rudely flaked stones or of any artificial objects whatsoever in the normal gravels of the delaware valley, and it therefore becomes necessary to examine somewhat critically such of the published evidence as seems to be seriously affected by these recent observations. it may be stated in beginning that no one disputes the glacial age of the trenton gravels. the question to be discussed is simply this,--is the evidence satisfactory that works of art have been found in these gravels? nothing else need be asked or answered. i do not take up this subject because i love controversy; disputation is really most distasteful to me. it happens that under the bureau of ethnology of the smithsonian institution i have been assigned to the work of making a survey of the archeology of the atlantic coast region in which large areas, especially in states south of mason and dixon's line, remained almost untouched by investigators, and two years have been consumed mainly in these southern areas. but there are questions that refuse to be confined to definite geographic limits, and evidence secured in one section is sometimes found to bear so directly and forcibly upon problems pertaining primarily to other sections that the student of these problems must perforce become a free lance, and unhesitatingly enter any province promising results of value, howsoever fully occupied it may be by other investigators. one of the most interesting and important questions growing out of the study of american archeology has, as we have seen, arisen in the delaware valley, and the turn taken by some of my work in the south and west is such that i cannot pass this question by without consideration. the necessity of taking up the subject of glacial man became more and more apparent as the years passed on, and people continued to say to me, "you must go to trenton; we are not satisfied with the present status of the question there; the evidence arrayed in favor of the theory of a paleolithic gravel man needs critical examination." the difficulty of taking up and re-examining evidence, of which the record only remains, is, however, very great, since in most cases the evidence rests upon or consists of field observations, and these cannot be recalled or repeated, and there is absolutely no means of testing directly the value of what is recorded. one may seek either to verify or to discredit the promulgated theories, but years of search may fail to produce a single new item of evidence bearing decisively upon the subject. it is possible that at one period numerous finds of implements should be reported from certain portions of the gravels, and that afterwards the whole remaining body of these formations should be worked over and searched without securing a trace of art; yet this latter evidence, being negative, need not necessarily be considered sufficient to overturn the original positive evidence if that happens to be of a high class. there is not the least doubt, however, that positive evidence may be so impaired by various defects and inconsistencies, that, unsupported by renewed and well verified observations, it will finally yield to the negative forces; and if the theories of a gravel man in the eastern united states, howsoever fortified by accumulated observations, are not really properly supported in every way, they are bound in time to fall to the ground. all i can reasonably hope to do now is to have the evidence relating to glacial man placed on trial, and so fully examined and cross-examined that those who accept gravel man need not longer do so blindly without knowing that there are two sides to the question, and those who do not accept him may know something of the reasons for the belief that is in them. the evidence employed to prove the presence of a race of men in the delaware valley in glacial times is confined almost wholly to the alleged discovery of rude implements in the glacial gravels. practically all the evidence has been collected by dr. c. c. abbott, and upon his skill as an observer, his faithfulness as a recorder, his correctness of judgment and his integrity of character, the whole matter stands. many visitors, men of high repute in archeology and geology, have visited the site, but the observations made on such occasions appear not to have been of a nature to be of great value in evidence, the finds being doubtful works of art or not having properly established relationships with the gravels in place. in the discussion of gravel man in eastern america a wide range of objects and phenomena has been considered, but the real evidence, upon which the theory of an ancient race and a peculiar culture must depend, is furnished by a hundred pieces--more or less--of rudely flaked stones said to have come from the gravels in place. and now what can be said with reference to this series of flaked stones further than that they are reported by the collector to have been found in the gravels at definite stated depths? i have elsewhere shown that they are not demonstrably implements in any case, that they are identical in every respect with the quarry-shop rejects of the american indian, that they do not closely resemble any one of the well established types of european paleolithic implements, and that they are not a sufficient index of a particular stage of culture. i shall now present such reasons as there may be for the belief, held by many, that they were not really found in the undisturbed glacial gravels. it is generally understood that the earliest reported gravel finds of importance were made on the banks of assanpink creek within the city limits of trenton, where the gravels to a thickness of twenty feet or more were exposed in a railway cutting. later the river bluff near the lower end of the city, where the gravels were exposed to a depth of from twenty-five to forty feet, yielded large numbers. these two sites, so far as i can learn, furnished at least three-fourths of the finds in place. other specimens were found singly in slight natural exposures, and in excavations for cellars, sewers, etc., at various points within the city limits. the river bluff was for a considerable period the favorite hunting ground of the searchers for rudely flaked stones, and many specimens were collected. the gravels were exposed in a steep, nearly straight bank, several hundred yards in length, the base of which was washed by the river. there can be no question that dr. abbott and others have found shaped objects of various classes upon and in the face of this river bluff, and the visitor to-day, although the bluff is now buried almost completely under city refuse, will hardly fail to find some rudely flaked form in the deeper gullies or upon the narrow river bank or beach at the base. dr. abbott explicitly states[ ] that he obtained certain of these specimens from the gravel outcrops, and that they were not in talus formations, but in undisturbed deposits. how then is it possible to do otherwise than accept these statements as satisfactory and final? [ ] abbott, c. c. primitive industry, pp. - . [illustration: =fig. .= sketch map of the trenton bluff, showing the relation of the sewer trench to the "implement" yielding slope.... a-b section line, =fig. =.] very recently, however, fortunate circumstances have brought the evidence furnished by this site again within our reach, thus enabling us to re-open the discussion under favorable conditions. what i had for some time desired to do in this case was, what i had already done at piny branch, d. c., and at little falls, minn., to open a trench into the face of the bluff, and thus secure evidence for or against the theory of a gravel man. this measure was, however, rendered impracticable by the occupation of the bluff margin by a city street; but it happened last summer that the city authorities, desiring to improve the sanitary condition of the city, decided to open a great sewer through this very bluff to get a lower outlet to the river. a trench twelve feet wide and some thirty feet deep, the full depth of the exposed gravels, was carried along the bluff just inside of its margin, opening out into the river at the point where the bluff turns toward the north-east. it was a trenching more complete and more satisfactory than any of which i had ever dreamed. at no point for the entire length of the bluff did the excavation depart more than forty feet from the line of the terrace face--from the upper margin of the slope upon which such plentiful evidence of a supposed gravel man had been obtained. the accompanying map and section, figs. and , will indicate the location of the trench, and show the exact relations of the natural and artificial exposures of the gravels. [illustration: =fig. .= sections made by the river and by the sewer, the former yielding many "implements," the latter yielding none.] i made several visits to the place, descended frequently into the great cut and examined the gravels and their contents with the utmost care, but without securing a trace of art. recognizing the vital importance of utilizing to the fullest extent this opportunity of testing the art-bearing nature of the gravels at this point, i resolved to undertake a systematic study of the subject. summoning my assistant, mr. william dinwiddie, from his field of operations in the south, i had him spend upwards of a month at the great trench, faithfully watching the gravels as they were exposed. mr. dinwiddie had worked three years under my personal direction, and had helped open upwards of twenty trenches through similar gravel deposits, and was therefore well qualified for the work. prof. w. j. mcgee, prof. r. d. salisbury, dr. stewart culin and dr. abbott also visited the place one or more times each. relics of art were found upon the surface and in such portions of the talus as happened to be exposed, but nothing whatever was found in the gravels in place, and the search was closed when it became fully apparent that the case was hopeless. it may be claimed that the conditions under which gravels are exposed in trenching as it progresses, are not as favorable for the collection of enclosed relics as where exposed by natural processes of weathering. this is true in a certain measure, as specimens may be obscured by the damp clinging sand which forms the matrix of the gravels. this, however, would interfere but little with the discovery of large flaked stones, such as we were led to expect in this place, and this slight disadvantage in detecting shaped pieces in fresh exposures is more than over-balanced by the treachery of weathered surfaces which often give to intrusive objects the appearance of original inclusion. the opportunity for studying the gravels in all their phases of bedding, composition and contents, was really excellent, and no one could watch the constantly renewed exposures hour after hour for a month without forming a most decided notion as to the implement bearing qualities of the formation. not the trace of a flaked stone, or of a flake or artificial fragment of any kind was found, and we closed the work with the firm conviction that the gravels exposed by this trench were absolutely barren of art. but dr. abbott claims to have found numerous implements in the bluff face a few feet away and in the same gravels. if this is true, the conditions of glacial occupation of this site must have been indeed remarkable. it is implied that during the whole period occupied by the melting of the ice sheet within the drainage of the delaware valley the hypothetical rude race lived on a particular line or zone afterwards exposed by the river to the depth of feet, leaving his strange "tools" there by the hundreds, while another line or zone, not more than forty feet away at most, exposed to the same depth by an artificial trench, was so avoided by him that it does not furnish the least memento of his presence. one vertical slice of the gravels twelve feet thick does not yield even a broken stone, while another slice not probably one-half as thick, cut obliquely through the gravels near by, has furnished subject-matter for numerous books and substantiation for a brace of theories. that no natural line of demarcation between the two section lines is possible, is shown by the fact that the formations are continuous, and that the deposits indicate a constant shifting of lines and areas of accumulation; thus it was impossible for any race to dwell continuously upon any spot, line or plane. this is well shown in the section, fig. , which gives the relations of the art-producing section of dr. abbott to the non-art-producing section of the sewer. the gravels were laid down entirely irrespective of subsequent cutting, natural or artificial; yet we are expected to believe that a so-called gravel man could have resorted for a thousand years to the space _a_, leaving his half shaped or incipient tools at all stages of the gravel building from base to top, failing entirely to visit a neighboring space _b_, or to leave there a single flake to reward the most faithful search. it is much easier to believe that one man should err than that a guileless race should thus conspire with a heartless nature to accomplish such extraordinary results. the easier explanation of the whole matter is that the objects found by dr. abbott were not really in the gravels, but that they are indian shop-refuse settled into the old talus deposits of the bluff, and that his eager eyes, blinded by a prevailing belief in a paleolithic man for all the world alike, failed to observe with their wonted keenness and power. [illustration: =fig. .= _a_, reputed "implement" producing zone of the river front. _b_, barren zone of sewer.] but this case does not stand alone. the first discoveries of supposed gravel implements are said to have been made when the pennsylvania railway opened a road bed through the creek terrace on the site of the present station. at first numerous specimens of rudely flaked stones were reported, and the locality became widely known to archeologists, but the implement bearing portions of the gravels--and this is a most significant fact--were limited in extent, and the deposit was soon completely removed, the horizontal extension containing nothing. at present there are excellent exposures of the full thickness of the gravels at this point, but the most diligent search is vain, the only result of days of examination being a deep conviction that these gravels are and always were wholly barren of art. it thus appears that here as well as upon the river front, the works of art were confined to local deposits, limited horizontally but not vertically, and a strong presumption is created that the finds were confined to redistributed gravels settled upon the terrace face in the form of talus. dr. abbott states that "at that point where i gathered the majority of specimens there is a want of stratification."[ ] it is well known that such rearranged deposits are often difficult to distinguish from the original gravels. in trenching an implement producing terrace at washington--where the conditions were probably quite similar to those at the trenton railroad station--i passed through eighty feet of redistributed talus gravels before encountering the gravels in place, and so deceptively were portions of these deposits re-set that experts in gravel phenomena were unable to decide whether they were or were not portions of the original formation (cretaceous). the question was finally settled by the discovery of artificially shaped stones in and beneath the deposits. [ ] abbott, c. c. th annual report of the peabody museum, p. . again, an implement bearing deposit of gravel was recently discovered by the late miss f. e. babbitt at little falls, minnesota, and sufficient (a very little) digging was done to satisfy the discoverer, and all paleolithic archeologists as well, that the objects were really imbedded in the glacial gravels. in the summer of i visited the place and carried a trench twenty feet horizontally into the terrace face on the "implement bed" level before encountering the gravels in place. the talus deposits were several feet thick, and were of such a nature that their true character could not be determined without careful and extensive trenching. the whole talus deposit was here well stocked with indian quartz quarry-shop rejects, which were as usual of paleolithic types, and it was but natural that miss babbitt's conclusions, although based as they necessarily were upon inexpert observations, backed by such well known "types" of "implements" should be unhesitatingly accepted by believers. the occurrence of these telling examples of the deceptive appearance of re-set gravels would seem to justify and emphasize the conviction created by a critical examination of the two leading so-called paleolithic sites at trenton, that dr. abbott, notwithstanding his asseverations to the contrary, has been deceived. very strong support, it seems to me, is given to this conclusion by the recently published opinion of the late dr. h. carvill lewis, a glacialist familiar with the trenton region, and with the work of dr. abbott at the period of his paleolithic castle building. dr. lewis is reported to have maintained before an open meeting of the academy of science in philadelphia "that what dr. abbott believed to be undisturbed layers (of gravel) were those of an ancient talus."[ ] this remark may refer to both the main sites--the one at the railroad station and the other at the river front--or possibly only to the former. i have also heard it stated that that eminent scholar, dr. leidy, who must have had ample opportunities of forming correct opinions upon the subject, held pretty much the same views of dr. abbott's finds. [ ] brinton, d. g., science, oct. , p. . [illustration: =fig. .= a freshly formed gravel bluff.] [illustration: =fig. .= early stage of talus formation.] [illustration: =fig. .= an ancient talus.] to make the above criticism entirely clear, a few words of explanation of talus phenomena may be added. as a river cuts its channel deeper and deeper into deposits of gravel a section is gradually exposed, but the gravels break down readily under atmospheric influences and the exposed face does not retain a high angle. the upper part crumbles and descends toward the base, there to rest against the slope or to be carried away by the stream. a supposititious case will be convenient for illustration. a gravel terrace twenty feet in height is encroached upon by the river at high water and undermined, and the face breaks down vertically, leaving an exposure as illustrated in fig. . in a very short time the upper portions become loosened and fall below, giving a steep slope as seen in fig. . the process goes on with gradually decreasing rapidity, and if the river does not again encroach seriously, a practically stable slope is reached, as shown in fig. . such a talus may be hundreds or even thousands of years old, but there is rarely any means of determining its exact age. if the gravels are homogeneous in character, the talus will simulate their normal condition so completely that the distinction cannot be made out in ordinary gullies or by unsystematic digging. if the gravels contain varied strata the talus will be composite, and will be more readily distinguished from at least portions of the material in place. now it is important to observe what may be the possible art contents of such a talus as that shown in fig. . it may contain all objects of art originally included in that portion of the gravels represented by _a_, _b_, _c_, together with all articles that happened to be upon the surface _b_, _c_, beside such objects as may have accumulated from dwelling or shop work upon its own surface, after the slope became sufficiently reduced to be occupied for these purposes. a talus is therefore liable to contain, and in the utmost confusion, relics of all periods of occupation, supposing always that there were such periods, from the beginning of the formation of the gravel deposits down to the present moment. as a rule such a talus, if art-containing, will have a large percentage of shop and quarry-shop refuse, for the reason that the exposed gravels, and the banks and beds of rivers cutting them, furnish, as a rule, a good deal of the raw material utilized by workers in stone, and the shops in which the work was done are usually located upon the slopes and outer margins of the terraces. although there is the possibility of very considerable age for these talus deposits, it is unlikely that any of them date back as far as the close of the glacial epoch or at all near it, for rivers change back and forth constantly, undermining first one bank and then the other, so that a very large percentage of our talus deposits have been formed well within the historic period. at trenton the constantly exposed gravel banks afforded considerable argillite in bowlders, fragments and heavy masses, as well as some other flakable stones of inferior quality little used, and it is inevitable that the indian who dwelt upon the shores of the river should have sought the workable pieces along the bluff, leaving the refuse everywhere; and it is a necessary consequence that the terrace margin, the bluff face, and the talus deposits, places little fitted for habitation, should for long distances contain no trace of any art shapes save such as pertain to manufacture. thus are fully and satisfactorily accounted for all the turtle backs and other rude forms that our paleolith hunters have been so assiduously gathering. nothing can be more fully apparent than that no other race than the indian in his historic character and condition need be conjured up to reasonably account for every phase and every article of the recovered art. mistaken interpretations of the nature of shop rejects, and the common association of these objects with redistributed gravels, are probably accountable for the many misconceptions that have arisen. talus deposits form exceedingly treacherous records for the would-be chronologist. they are the reef upon which more than one paleolithic adventurer has been wrecked. relics of art attributed to gravel man have been collected, so far as i can gather from museum labels and from incidental references in various publications, from a number of sites aside from the two already referred to. these are scattered over the city, and the finds were made mostly in exposures of the gravels that remained visible for a short time only, as in street and cellar excavations and well pits. these reported finds can never be brought within the range of re-examination, and the searcher after unimpeachable testimony must content himself with placing them in the doubtful column on general principles. urban districts are so subject to disturbance through cutting down of hills, filling in of depressions, grading of streets, digging of foundations, cellars, sewers, wells and graves that no man can, from a limited exposure such as those producing the reported tools necessarily were, speak with certainty of the undisturbed nature of the deposits penetrated. it is doubtful if any one is justified in publishing such observations at all without serious query. such testimony is liable to fall of its own inherent weakness, being absolutely valueless if unsupported by collateral evidence of real weight. it can only be made permanently available to science by the discovery of something unusual or unique with which to couple it, something decidedly un-indian in character or type, as for example the two skulls now in the peabody museum. these objects and the antler knife-handle exhibited with them may be alluded to as the only finds so far made at trenton, having of themselves the least potentiality as proof and these skulls and this knife-handle must yet be subjected to the rigid examination made necessary by the importance of the conclusions to be based upon them. something may now be said concerning the art remains upon which this discussion hinges, and upon which conclusions of the greatest importance to anthropology are supposed to depend. let us pass over all that has been said with regard to their manner of occurrence and association with the gravels and ask them simply what story they tell of themselves. does this story, so far as we are able clearly to read it, speak of a great antiquity and a peculiar culture, or does it hint rather at vital weaknesses in the position taken by the advocates of these ideas? we shall see. the history of the utilization of rudely flaked stones in the attempt to establish a gravel man in america has never been written, but as read between the lines of paleolithic literature, it runs about as follows: the theory of a very rude and ancient people, having a unique culture and certain peculiar art limitations, was developed in europe many years ago in a manner well known and often rehearsed. this people was associated with the ice age in europe, and this epoch, with its moraines and till and sedimented gravels, was found to have been repeated in america. it was the most natural thing possible that these discoveries should carry with them the suggestion that man may have existed here as in europe during that epoch, and that his culture was of closely corresponding grade. these were legitimate inferences and warranted the instituting of careful researches, but it was a dangerous suggestion to put into the minds of enthusiastic novices with fertile brains and ready pens. the idea was hardly transplanted to american soil before finds began to be made. the so-called "types" of european paleoliths suggested the lines upon which finds here should be made, and everything in the way of flaked stones connected directly or indirectly with the glacial gravels which had not yet been fully credited to and absorbed by the inconvenient indian, was seized upon as representing the ancient time and its hypothetic people and culture. in the early days of the investigation the various rude forms of flaked stones, resulting from failures in manufacture, had not been studied, and were shrouded in convenient mystery, and they thus became the foundation of the new archeologic dynasty in america, the dynasty of the turtle-back. dr. abbott states in his first work[ ] that these rude "implements" are not especially characteristic of any one locality, but seem to be scattered uniformly over the state. specimens of every type, he says, are "found upon the surface, and are plowed up every spring and autumn; but this in no way militates against the opinion that these ruder forms are far older than the well-chipped jasper and beautifully-polished porphyry stone-work."[ ] at that stage of the investigation it was not at all necessary that a specimen should come from the gravels in place or from any given depth, since the "type" was supposed to be easily recognized and was a sufficient means of settling the question of age. [ ] abbott, c. c. the stone age in n. j., sm. rep. , p. . [ ] ibid, p. . rude "implements" were called for and they were found. the only requirements were that they should not be of well-known indian types, that they should be rude and have some sort of resemblance to what were known as paleolithic implements abroad. since most of these so-called gravel implements of europe are also doubtless the rejects of manufacture resemblances were readily found. the early attempts to utilize these rejects in support of the theory, and make them masquerade creditably as "implements" with specialized features and self-evident adaptation to definite ice-age uses, now appear decidedly amusing. gradually, however, the lines have been drawn upon this early license, and it is to-day well understood by all careful students, that since the rude forms are so often repeated in modern neolithic refuse, the only reliable test of a gravel "implement" is its occurrence in the gravels in place. that a particular "implement," said to have been obtained from the gravels, is of "paleolithic type," does not in the least strengthen its claims to being a _bona fide_ gravel implement; nor does its easy assignment to a "type" give any additional value to the collector's claim that the gravels said to contain it are implement bearing. the very names, "rude implement," "paleolithic implement," etc., carry with them a certain amount of mysterious suggestion; one thinks of unique, significant shapes and of strange, archaic uses. at their mere mention, the great ice sheet looms up with startling realism, and the reindeer and the mighty mammoth appear upon the scene. the reader of our paleolithic literature is led to feel that these antiquated objects carry volumes of history in their worn and weather-beaten faces, but this is all the figment of fertile brains. these objects have without exception the appearance of the most commonplace every-day rejects of manufacture without specialization and without hidden meaning. they tell of themselves no story whatsoever, save that of the oft-repeated failure of the aboriginal blade maker in his struggle with refractory stones. this will be shown with greater clearness farther on. but the scheme does not end with the repetition of a european state of affairs. our gravel archeologists have not been content to adopt that feature of the foreign scheme which utterly destroys the paleolithic race before a higher culture is brought upon the scene. it was thought to improve upon the borrowed plan by allowing for a gradual development upward from the paleolithic stage, represented exclusively by a class of meaningless bits of flaked stone, through a period less rude, characterized by productions so far advanced as to be assigned to a definite use. these latter productions consist mainly of rather large and often rude blades, sometimes plain, but generally notched or modified at the broader end as if to be set in a handle, or attached to a spear or arrow shaft. these were assigned to post-glacial times in such a way as to bridge or partly bridge the great space between the glacial epoch and the present. they were separated arbitrarily from the body of the collections of the region, and referred to as probably the work of an eskimo race. this arrangement produced a pleasing symmetry and completeness, and brought the history of man down to the beginning of the indian epoch, which is represented by all of those forms of art with which the red man is historically associated. three principal periods are thus thought to be represented by the finds at trenton; and in the arrangement of the collections these grand divisions are illustrated by three great groups of relics, which are looked upon by the founders of the scheme as an epitome of native american art and culture. by others this grouping is looked upon as purely empirical, as an arbitrary separation of the normal art remains of the historic indian, not suggested by anything in the nature or condition of the objects, nor in the manner of their discovery. the "eskimo" feature of the scheme requires a more detailed examination than can be given it here. it may be stated, however, that the separation of the so-called eskimo spear points, or whatever they may be, from the great body of associated articles of flaked stone, appears to be a highly arbitrary proceeding. that they were extensively made by the indians is proved by the occurrence of refuse resulting from their manufacture on modern shop sites, and that they were used by the indian, is equally apparent from their common occurrence on modern dwelling sites. the exceptionally large size of the argellite points is readily accounted for by the nature of the material. it was the only stone of the region well adapted to the manufacture of long blades or projectile points. jasper, quartz and flint have such minute cleavage that, save in rare cases, small implements only could be made from them. their peculiar manner of occurrence, described at so much length by dr. abbott,[ ] has been given undue consideration and weight. the phenomena observed may all be accounted for as a result of the vicissitudes of aboriginal life and occupation within the last few hundred years as fully and satisfactorily as by jumping thousands of years backward into the unknown. [ ] abbott, c. c. popular science monthly, dec., . whatsoever real support there may be for the "eskimo" theory, either in the published or the unpublished evidence, it is apparent that under the present system of solitary and inexpert research, the scientific world will gain little that it can utilize without distrust and danger. whatsoever may be the final outcome--which outcome is bound to be the truth--it is clear that there is little in the present evidence to warrant the separation of a "paleolithic" and an "eskimo" period of art from that of the indian. that the art remains of the trenton region are essentially a unit, having no natural separation into time, culture or stock groups, is easily susceptible of demonstration. i have already presented strong reasons for concluding that all the finds upon the trenton sites are from the surface or from recent deposits, and that all may reasonably be assigned to the indian. a find has recently been made which furnishes full and decisive evidence upon this point. at point pleasant, on the delaware, some twenty-five miles above trenton, there are outcrops of argillite, and here have been discovered recently the shop sites upon which this stone was worked. there are two features of these shops to which the closest attention must be given. the first is that they are manifestly modern; they are situated on the present flood plain of the delaware, and but a few feet above average water level, the glacial terrace here being some forty or fifty feet in height. these shops, therefore, represent the most modern phases of aboriginal industry, and may have been occupied at the coming of william penn. the second point is that every type of flaked argillite found in the trenton region, associated with the gravels or otherwise, is found on this site. it was to a certain extent a quarry site, for the great masses of argillite brought down by the floods were here broken up and removed from the river banks or bed. it was a shop site, for here the articles, mainly blades, were roughed out, and it was also a dwelling place--a village site--where all the specialized forms of flaked stones made from the blades were prepared for use. here are found great numbers of the rude failures, duplicating every feature of the mysterious "paleolith" with which our museums are stocked, and exhibiting the same masterly quitting at just the point "where no further shaping was possible."[ ] here we see the same boldly manipulated "cutting edge," the "flat bottom" and "high peak," and the same mysteriously weathered and disintegrated surfaces, so skillfully made, by a nice balancing of accidents,[ ] to tell the story of chronologic sequence in deposition. [ ] abbott, c. c. smithsonian report, , p. . [ ] ibid. primitive industry, p. . beside the failures, we have here, as on other quarry shop sites, the evidence of more advanced work, the wide, thick, defective blades, and many of the long, thin blades broken at or near the finishing point. here, too, just back of the roughing-out shops, are the dwelling sites from which many specialized forms are obtained. the "eskimo" type is fully represented as well as the ordinary spear point, the arrow point, and the perforator of our indian. there is not a type of flaked argillite known in the delaware valley that may not be duplicated here on this modern indian site, and this has been known by local archeologists for years. why so little has been said about the matter is thus explained. dr. abbott, in , discovering this site, and finding "typical paleolithic implements" (the ordinary ruder forms of rejects) among the refuse, was so entirely at a loss to explain the occurrence that he felt compelled to again "take up the examination of the gravel deposits of the valley of the delaware" with the hope of "finally solving the problem."[ ] the true conditions would have been at once apparent to any one not utterly blinded by the prevailing misconceptions. [ ] abbott, c. c. annual report of the curator of the museum of american archeology, university of pennsylvania. no. , p. . the entire simplicity of the archeologic conditions in the delaware valley may be further illustrated. had william penn paused in his arduous traffic with the tawny delawares, and glanced out with far-sighted eyes from beneath the pendant branches of the great elm at shackamaxon, he might have beheld an uncouth savage laboriously fabricating rude ice age tools, making the clumsy turtle-back, shaping the mysterious paleolith, thus taking that first and most interesting theoretical step in human art and history. had he looked again a few moments later he might have beheld the same tawny individual deeply absorbed in the task of trimming a long rude spear point of "eskimo" type from the refractory argillite. if he had again paused when another handful of baubles had been judiciously exchanged, he would have seen the familiar redskin carefully finishing his arrow points and fitting them to their shafts preparatory to a hunting and fishing cruise on the placid delaware. thus in a brief space of time penn might have gleaned the story of the ages--the history of the turtle-back, the long spear point and their allies--as in a single sheaf. but the opportunity was wasted, and the heaps of flinty refuse left upon the river bank by the workmen were the only record left of the nature of the work of that day. two hundred years of aboriginal misfortune and quaker inattention and neglect have resulted in so mixing up the simple evidence of a day's work, that it has taken twenty-five years to collect the scattered fragments, to sift, separate and classify them, and to assign them to theoretic places in a scheme of culture evolution that spans ten thousand years. yet is there really nothing in it all, in the theories, the observations, the collections and the books? do i speak too positively in condemnation of the results of years of earnest investigation? perhaps so, but the voluminous testimony is so overloaded with inaccuracies, the relics of unscientific method and misleading hypotheses, that every item must be sharply questioned; and the conclusions reached so far overstep the limits warranted by the evidence, that heroic measures alone can be effectual in determining their exact value. if, as many believe, vital errors have been embodied in the evidence presented by the advocates of the theory, it is impossible to state the case too strongly. error once fully absorbed into the literature of science has many advantages over the tardy truth; it is strongly fortified and must be attacked and exposed without fear or favor. truth involved with it cannot permanently suffer. if the twin theories of a gravel and a paleolithic man in eastern america are to be assailed as unsound or as not properly supported, it should be done now while the originators and upholders are alive and alert to sustain their positions or to yield to the advances of truth. i do not wish to wrongly characterize or to unduly minimize the evidence brought to bear in favor of these theories. i do intend, however, to assist the world so far as possible in securing an exact estimate of all that has been said and done, and all that is to be done. in a previous article i have examined the evidence relating to paleolithic art in the eastern united states, and have indicated its utter inadequacy and unreliability. in this paper the testimony relating to the occurrence of gravel art, in the locality most fully relied upon by advocates of the theory, has been partially reviewed and subjected to the strong light of recent observations. it is found that the whole fabric, so imposing in books and museums, shrinks away surprisingly as it is approached. the evidence furnished by the bluff face and by the railway cutting, the two leading sites, is fatally weakened by the practical demonstration of the fact that the gravels proper are at these points barren of art remains. in endeavoring to naturalize an immigrant hypothesis, our gravel searchers, unacquainted with the true nature of the objects collected and discussed, and little skilled in the observation of the phenomena by means of which all questions of age must be determined, have undoubtedly made grievous mistakes and have thus misled an expectant and credulous public. the articles themselves, the so-called gravel finds, when closely studied are found to tell their own story much more fully and accurately than it has heretofore been read by students of archeology. this story is that the art of the delaware valley is to all intents and purposes a unit, that there is nothing unique or especially primitive or ancient and nothing un-indian in it all. all forms are found on demonstrably recent sites of manufacture. the rude forms assigned by some to glacial times are all apparently "wasters" of indian manufacture. the large blades of "eskimo" type are only the larger blades, knives and spear points of the indian, separated arbitrarily from the body of the art-remains to subserve the ends of a theory, certain obscure phenomena of occurrence having been found to give color to the proceeding. to place any part of this art, rude or elaborate, permanently in any other than the ordinary indian category will take stronger proofs than have yet been developed in the region itself. the question asked in the beginning, "are there traces of glacial man in the trenton gravels?" if not answered decisively in the negative, stands little chance, considering present evidence, of being answered in the affirmative. in view of the fact that numerous observations of apparent value have been made in other sections, there is yet sufficient reason for letting the query stand, and we may continue to cherish the hope that possibly by renewed effort and improved methods of investigation, something may yet be found in the trenton gravels clearly demonstrative of the fascinating belief in a great antiquity for the human race in america. the evidence upon which _paleolithic man_ in america depends is so intangible that, unsupported by supposed analogies with european conditions and phenomena, and by the suggestions of an ideal scheme of culture progress, it would vanish in thin air; and if the theory of a _glacial man_ can summon to its aid no better testimony than that furnished by the examples examined in this paper, the whole scheme, so elaborately mounted and so confidently proclaimed, is in imminent danger of early collapse. =w. h. holmes.= geology as a part of a college curriculum. the demand for scientific studies as a part of the college curriculum is felt by all those who have to do with the provision of higher instruction for american youth. the reasons for this may be various, but a fundamental reason is found in the tendency among the american people in particular, and in this age in general, toward practicality in all things. applied to education this practicality asks for a training which shall have a direct bearing upon the business of life to be followed immediately after the training period is ended. it means a differentiation of subjects and specialization in methods to adjust the education to the different functions which the students taking it are preparing for. it calls for a professional education for those who expect to become lawyers, doctors, ministers, or teachers,--a technical education for those who are to engage in the arts of the mechanical or civil engineer, or of the architect. it results not only in the establishment of colleges and universities devoted to this kind of education, but it affects the methods of the high schools and academies, and is felt down to primary schools, and on the other hand the older institutions founded on a different plan are adapted to the popular demand by the addition to the regular studies of "electives," chosen not always for their value or disciplinary studies, but because of the practical applicability of the information to be derived from them, to the business of the student. without discussing the relative merits of the two ideas of education, the chief contrast between them may be found in the character of the results sought. the knowledge of things and their uses is of chief importance in the practical education; the knowledge of ideas and skill in their use is the aim of the liberal education. geology is one of the sciences which most men will at once classify as among the practical sciences. it deals with matters of practical importance to everybody. coal, iron, the metals, silver, gold, tin, lead, building stone, sand, clay, petroleum, and natural gas, and all geological products are essential materials of modern civilization, and a knowledge of them and of their modes and places of occurrence is one of the requisites of an education, either from the practical or the liberal point of view. so too the dynamics of atmospheric and hydraulic erosion, the agency of rivers and oceans in destruction, removal and reconstruction of geological formations have their eminently practical bearings upon the various arts of engineering. while the practical value of geology is thus evident and undisputed, it is not on this account that its importance as a part of a college course of education is urged. as a practical study geology becomes the centre of a group of studies requiring years for mastery. chemistry and physics are primarily essential to a full understanding of the most common of geological problems. and to use geological facts and phenomena, an acquaintance with the complex methods of engineering, civil and mechanical, which again call for a thorough mastery of mathematics, is necessary. mineralogy and petrography, metallurgy and mining engineering have each reached a stage of development entitling them to the rank of separate sciences, but the practical training of the geologist should include them all. when we add the biological sciences connected with historical geology, paleontology, zoölogy and botany, with all the laboratory and field work required for their proper study, we have a group of affiliated branches of learning requiring four or five years of continuous study after the student has learned how to study. it is plain therefore that only a specialist, one who is willing to neglect other studies, or who has previously had a liberal training, can perfect himself on the practical side in the science of geology. but irrespective of its practical uses, as a means of training and supplementary to the ordinary studies of a college curriculum, geology is one of the most useful of the sciences of observation. it is in providing that particular training to which president eliot has recently called attention in the _forum_ (dec., , wherein popular education has failed), that geology can be used to such advantage. speaking particularly of the lower education, president eliot says it is "the judgment and reasoning powers" that particularly require attention. their systematic development is to be attained in the four directions of "observing accurately, recording correctly, comparing, grouping and inferring justly, and expressing cogently the results of these mental operations." (p. .) the attainment of these ends is one of the purposes of liberal education, whether it be in the primary school or in the university. and geology, or any other science, is of value in a college course in proportion to its fitness for the exercise and development of these functions of the student. geology may be taught without regard to these ends, and then it is valuable from the practical point of view, but when we examine it in respect of its availability as a disciplinary study we find it offering particular attractions. using the distinction between theory and practice, which is as old as aristotle, geology in its theoretical aspect is more easily comprehended than is the theoretical aspect of most of the modern sciences. this arises first from the fact that the facts and phenomena are of a simple and grand nature, making it possible for the teacher to direct certain attention to the specific facts under consideration. the water of the rivers, the mud by the road side, the rocks and sands on the shore are familiar objects to all, and it is a simple matter to call attention by ordinary language to the specific facts regarding them, which, analyzed out, are to form the basis of exact ideas and scientific definition and classification. geology is the one science among the natural sciences which may begin with the common language of the pupil, and by means of such language alone may build up ideas of precise phenomena in scientific terms. physiography or physical geography surpasses geology proper in this particular, as the admirable work of professor davis is showing, and on this account it is the best introduction to geology. but the very largeness and indefiniteness of the facts are in the way of the use of physical geography for the exercise of the finer and more exact functions of observation. the disciplinary value of classics and mathematics is to a considerable extent derived from this quality, the precision with which the words or figures kindle like ideas. so long as the object of the training is to teach the knowledge of ideas and how to use them, classics and mathematics are the simplest and purest means of developing a liberal education. the addition of sciences to the college course is not because of the usefulness of the knowledge of things thus to be gained, but because the language of the sciences is essential to call forth the observation and the exercise of the accompanying mental operations. when it comes to dealing with the ideas associated with particular sense-observation, where form or motion can not be expressed in simple mathematical terms, language can not communicate a new idea or kindle it in another mind with precision. it is necessary by some means to recall or to present the object itself to the student. in the teaching of science this point is of great importance, and much of the unsatisfactoriness of science-teaching is doubtless due to failure to note it. no circumlocution of words can arouse in another or communicate to him the idea appropriate to a sensation he has never felt. the blind man whose eyes are opened sees men as trees walking. in the use of science for elementary training (and the training is elementary until the student is capable of investigating and interpreting the facts and phenomena of a science directly) that science is the better which deals with objects which are simple, common and easily observed. such is geology in some of its aspects. every time the student walks in the country he sees the facts discussed in the text-book or by his teacher; and from attention to those with which he is already familiar he can be readily led to observe and give attention to others and to analyze those already in his mind by properly directed questions. in the field of geology are found the ready means for the exercise and development of observation and thought. the learner begins with ideas which every intelligent mind associates with the objects described or named, and by degrees the marks of his knowledge are increased, the relations of things are grasped, and the content of his ideas associated with the language of his science is enlarged. in the process of learning the science he has been building up his stock of knowledge of facts and phenomena, but, of more importance than that, he has learned the method of observing and of scientific thinking. he has had training in the methods of reducing the hard facts of nature to the laws of thought and practice, he has seen the method by which theoretical order is made out of the interminable confusion and complexity of natural things. beside this primary reason for the use of geology as a disciplinary science-study, there is a second reason arising from the symbolic nature of a large group of its facts. this aspect of the science is best seen in the historical and stratigraphical parts of geology, in which fossils are the chief data for study. the interpretation of a fossil into a species of organism, having its definite place in the elaborate classification of the zoölogist, or as an indicator of the time and place and mode of formation of the strata in which it is buried, is, to be sure, a most intricate and, at first thought it would seem, an unattractive process. but no more so, i would say, than the interpretation of a series of greek characters. the interpretation of the greek reveals to us the richest results of human thought and most perfect laws of human speech, and we find therefore in the analysis required the most perfect discipline of the powers of speech and language. the fossil too holds, ready to be revealed, the story of the history of the world and the laws of the evolution of the organic life of the globe, and records an inexhaustible wealth of information regarding the laws of nature. but as an instrument of intellectual discipline its great merit lies in its symbolic nature. it is this symbolic character of the classical languages and of the mathematics which fits them to be universal means of liberal training. the symbolic nature of the fossil fits it to become the exponent of training in the pure science of nature. the fossil is a mark which stands for something, and thus, in the nature of things, it asks for interpretation. as a symbol it stimulates minute and accurate observation, and kindles close and exhaustive thought; as a symbol it leaves us the ideas it has engendered after it is lost to memory as an observation. thus the value of its study does not depend upon the retention in the memory of the facts brought before the mind, but in the training of the mental processes required in its interpretation. the study of this branch of geology exercises and develops all the faculties which are specially exercised in any scientific investigation. another aspect in which it is an ideal means for such training comes from the fact that it is equally valuable at every stage of progress of the student. when first examined it means nothing to him. he knows nothing of organism, of strata, of geological time. the fossil gains meaning only as he is able to put meaning into it. the student must ask questions, and as step by step he answers his questions by more minute and wider examination, the fossil holds a fuller interpretation. his studies lead him to investigation of the whole field of nature, the rocks, the formation of deposits, the action of the elements, the conditions of life, the forms of organism, their functions and habits, the laws of growth, their adaptation to environment, the changes of events in time, the efforts of association and struggle for life, the principles of evolution and development--the migration and origin and extinction of organisms on the globe. nothing in nature is without interest to him. further than this the amount of good he gains is not measured by the number of fossils he studies, but by the wideness of his research. a handful of fossils from some one fossiliferous ledge may be the text for a year's study, and the methods acquired in the study may be the nucleus of a life's work. in this department of geology the possibilities for new discoveries, new developments of science are almost endless. as a single author thoroughly read develops a wealth of knowledge of the laws of language and thought, so geology may be studied by the use of a limited set of its phenomena and become the introduction to the exhaustive study of natural science. another advantage attaching to geology as a science-study for the college curriculum, arises from the fact that it may be pursued deeply without the elaborate aid to the senses required in other sciences for making minute record or measurement of facts or phenomena. as in language and mathematics, it is essential to acquire a familiarity with the grammar, the dictionary and the symbols, formulas and rules of their usage before the finer training in the use of thought begins, so the vocabulary and the definitions of a science must be acquired before much use can be made of the higher discipline to be derived from scientific study. in language study this higher training comes from practice in making the minute analysis, in detecting the fine shades of meaning expressed in the literature itself. so it is important in selecting a science to be used as a disciplinary study that the facts and laws of nature with which it is concerned should be capable of clear and precise definition, and, moreover, that it should furnish a field for the study of the minute and intricate relationship existing between the different facts which are to be attained by personal inspection of the objects themselves. in most of the sciences this deeper exercise of scientific thought requires for its successful pursuit artificial aids to the common senses of observation. chemistry must have its purified acids and reagents, test tubes, and delicate scales for measurement of weight and volume. mineralogy must have its chemical analyses, or optical measurements so fine that microscopes of highest power are essential tools for the investigation. physics must have the most delicate measurements of time and space and weight. botany, for the earlier stages of study, is fully equal to geology in these respects, but its scope is much less general. zoölogy requires dissections calling for skill in manipulation, and in other respects is ill adapted to general classes. but precision in the intellectual processes of observation and reasoning can be cultivated in the use of geological facts to their highest and widest perfection, with scarcely any aids to the normal faculties of observation. a couple of hammers, a pocket lens, a chisel and a few pointed steel tools for revealing fossils, a tape line, compass and clinometer are the few equipments that will enable the geologist to carry his investigations to almost any degree of thoroughness. what has already been said applies to the study of the pure science of geology either in the field or in the laboratory. there is still another use to which this, as other sciences, may be put in disciplining the college student in directions not provided for by literary or mathematical studies,--the study of man as an investigator. in the pursuit of the study of geology, the first instruction must be received in didactic form, but after the text-book and lecture stage is passed, or while it is under way consultation of the literature of the sciences is appropriate. in the use of scientific literature the critical judgment is brought under training, and the varying interpretations of well known phenomena by expert scientists suggest the prominent part which the notions already in the mind play in the interpretation of the external facts observed. the experienced geologist will recall many cases of honest report of impossible facts by men who are unable to distinguish between what they saw and the false interpretations they made of these observations. one man will report that a live toad jumped out of the middle of a solid piece of coal, when it was heated in the stove; another will swear that he saw a fossil shark's tooth taken out of a ledge of trenton limestone. it is evident that our memory of observation is not the revival of the object producing the sensation, but of the idea we framed of the sensation at the time. the study of original descriptions of objects of nature reveals the fact that the describer uses the ideas he already has in his mind as he does the standard foot-rule in his hand for measuring that which he describes, and it is by the study of scientific literature and the comparison of views of many scientists that this highest discipline of the observational faculties is attained--the power to determine the personal equation of error for the observer, and thus see through his descriptions a truer representation of the facts than the observer himself saw. geological literature is admirably adapted for this higher discipline, and in no field of science (i think not in astronomy itself), has wider and more comprehensive thought been applied than in geology. while other branches of science have been developed and become more narrow and special in their treatment of the facts concerned, geology still stands as the most comprehensive of all the sciences of nature. h. s. williams. =yale college=, november , . the nature of the englacial drift of the mississippi basin. it is of some importance, both to the practical work of the field and the theoretical deductions of the study, to determine the nature and amount of the drift that was carried forward in the body of the ancient continental glaciers, and brought out on their terminal slopes and at length deposited at their frontal edges, and to distinguish it from that which was pushed or dragged or rolled along at the bottom of the ice.[ ] it may be helpful to indulge in a speculative discussion at the outset to prepare the way for the specific evidence and the inferences to which it leads. [ ] debris, which may be imbedded in the basal layer of the ice during some part of its transportation, but which is brought down to the bottom and subjected to basal action in the latter part of its course, and ultimately becomes a part of the basal deposit, is not here included in the englacial drift. whenever a prominence of rock is overridden and enveloped by a glacier of the free-moving continental type, one of two things takes place; either that part of the ice which passes over the summit of the prominence flows down its lee slope, carrying whatever debris it dislodges down to the rear base, and thence onward along the bottom of the ice, or else the currents which pass on either side of the prominence close in behind it before the corresponding current which passes over the summit reaches the point of their junction, in which case the summit current is forced to pass off more nearly horizontally into the body of the ice, carrying with it whatsoever debris it has dislodged from the summit of the prominence and embodied within its base. the law of the phenomena appears to be that whenever the height of the prominence is less than one-half the base, measured transversely to the movement of the ice, the summit current will follow down the lee slope; but whenever the height of the prominence is more than one-half the transverse base, the lateral currents will close in on the lee, and the summit current will flow off into the body of the ice. this simple law is, however, subject to very considerable modifications from several different sources which may be grouped under ( ) differences in the friction arising from basal contact, and ( ) differences of internal friction and mobility. the lateral currents will expose more surface to the sides and base of the hill and the adjoining plain, and will be more subject to conflicting currents, while, on the other hand, being deeper currents, they will presumably be more fluent. these and other qualifying conditions will go far to vitiate the application of the law, but its statement may have some value as representing a general conception of the phenomena. when the height of the prominence becomes great relative to the total thickness of the ice, the fluency of the summit current may be much reduced relative to that of the central parts of the lateral currents. when the prominence reaches the surface, blocks dislodged from it are borne away on the surface of the glacier, and constitute superglacial drift. blocks dislodged from near the summit, but below the surface of the ice, are presumably carried onward in the upper zone of the glacier; while other blocks detached at various but sufficient heights on the side of the prominence are doubtless borne around into the lee and carried forward in the same vertical plane as the summit stream, so that there comes to be a vertical zone set with boulders moving on from the lee side of the nunatak. lofty ledges or plateaus, with vertical or undercut faces, furnish similar means for the lodgment of debris within the body of the ice. in these and doubtless in other ways it appears that there came to be lodged directly within the body of the pleistocene glaciers at some considerable distances above their bases, blocks derived from rock prominences that rose with sufficient steepness above the general surface of the country over which the ice passed. the lodgment of debris on the lateral borders of glaciers is neglected here because it has little or no applicability to the phenomena of the upper mississippi basin. it is also doubtful whether any prominences protruded through the ice except near the thin edge, when advancing and retreating, and these are too inconsiderable to merit attention. it is obvious, upon consideration, that blocks detached from summits or from the sharp angles of out-jutting ledges or plateaus might suffer some glacial abrasion in the process of their dislodgment and transposition along the crest or projecting angle, but that in general such abrasion would be small, and, in most cases, nearly or quite absent. the debris so incorporated in the body of the ice would be, for the most part, angular, and, as it was brought forward in the ice, it would probably suffer very little abrasion. if it continued to move forward in the plane in which it started, descending only so much as the bottom wastage of the ice required, it would be brought out to the terminal slope of the ice sheet by virtue of the melting away of the ice above, and thence it would be carried on down the terminal slope as superglacial debris, and dropped at the frontal edge. if this be the true and full history, there would be no commingling of this englacial matter with the subglacial debris. it is evident, that the englacial matter brought forward from the crest of one prominence would be intermingled with that brought forward from other prominences lying in a line with it, or lying so near it that the lateral spreading of the debris would lead to commingling. it is also clear that variations in the direction of currents would tend to the same result, so that englacial matter from different prominences of the same general region might be commingled. so also englacial material, by crevassing and by the descent of streams from the surface to the base, would be carried down to the bottom and mingled with the subglacial debris. so also blocks broken away from the base of the prominence which yielded the englacial erratics might be moved forward along the bottom parallel with the englacial material above, and lodged at any point along the line. it is therefore to be expected that the basal deposits will contain the same rock species as the englacial, but if there be no process by which the basal material is carried upward the reverse will not be the case, and there will be a clear distinction between the englacial deposit and the subglacial deposit, in composition as well as physical state. not a few glacialists, however, advocate in somewhat differing forms and phases the doctrine that basal material is carried upward into the body of the glacier and at length reaches the surface, and that at the extremity of the ice this is commingled with any erratics that may be englacial or superglacial by original derivation. this doctrine appears to have had its origin in the endeavor to explain the very common fact that glacial drift has been carried from lower to higher altitudes. erratics are often found lodged several hundred feet higher than the outcrop from which they were derived. it has never seemed to me, however, that this phenomenon necessarily was different in kind from that which takes place in the bottom of every stream; at least i have not come in contact with any instances that seemed to require a different explanation, except those connected with kames and eskers that require a special explanation in any case. we are so accustomed to view streams from above, and so accustomed to study the extinct glaciers from the bottom, that we are liable to overlook the community of some of the simpler processes involved alike in both phenomena. the dictum that water never runs up hill is measurably true of the surface currents of the ice as well as water, but it altogether fails when applied to the basal currents of either. it is probable that there is no natural stream of any length in which, at some part of its course, basal debris is not carried from lower to higher altitudes and lodged there. if the bed of any stream were made dry and the debris in it critically examined, it would be found that at numerous points the silts or sands or gravels had been carried from the bottom of some basin in its bed to the higher rim or bar or reef that bordered it on the downstream side. so i conceive that, on a grander scale, the natural result of the flow of the basal ice of a continental glacier over the inequalities of the country was the lifting of material from some of the lower horizons and its lodgment on the crests of ridges or the slopes or summits of mountains that lay athwart its course. so again, it is certain that a considerable part of the peripheral drainage of glaciers takes place through tunnels beneath the ice. it is reasonable to suppose that during the winter season, when the drainage is slack, these tunnels tend to collapse in greater or less degree, under the continued pressure of the ice and the "fattening" of the glacier, so that in the early part of the next melting season the contracted tunnels may be over-flooded by glacial waters. to the extent that these tunnels become incompetent the water would become ponded back in the crevasses and moulins by which the surface-water gains access to them. they thus come to have something of the force of water flowing in tubes, and may be presumed to be capable of forcing rounded material to some considerable height, and of carrying ice-imbedded boulders to any point reached by the stream. these tunnels probably undulate with the bottom, and lodgment along them takes place wherever enlargement permits. without, therefore, appealing to any upward cross currents within the ice itself, it is possible to explain the transportation of the drift from lower to higher altitudes. i have never seen phenomena of this kind that seemed to call for any other explanation than these. i am not prepared to say that there are no such phenomena. one of the purposes of this article will have been accomplished, if it shall call forth a critical statement of phenomena that require the assumption of internal upward movements of the ice to account for them, and of the criteria which distinguish such phenomena from those that may be referred to upward basal movements such as are common to all streams or to the exceptionally conditioned subglacial streams. that there are upward internal movements in most streams is as much beyond question as the existence of upward basal currents in rivers and glaciers, but they are dependent chiefly upon the velocity of the current and the irregularity of the bottom. theoretically, as i understand, a stream moving in a straight course on a perfectly smooth bottom would not develop an upward cross current. each lower layer would move slower than that above it by reason of basal friction, but they would move on in parallel lines. but if irregularity of bottom be introduced the parallelism is obviously destroyed, and if the velocity be high so that the momentum of the particles becomes great relative to their cohesion, irregular internal movements will result, and these will often be of a rotary nature in vertical planes bringing the basal parts of the fluid to the surface or the reverse. for this reason rapid streams abound in rotary currents, while slow streams do not. now it is quite obvious that a stream of water moving at a rate of three or four feet per day, or even fifty or sixty feet per day, would not develop perceptible upward currents, and certainly would not lift the lightest silt from its bottom. i do not think there are any theoretical grounds for believing that internal glacial currents are developed, which flow from base to surface, carrying bottom debris to the top. one of the most remarkable expressions of the drift phenomena of the upper mississippi region consists of belts of boulders stretching for great distances over the face of the country, and disposing themselves in great loops after the fashion of the terminal moraines of the region with which they are intimately connected. besides this, there are numerous patches of boulders of more or less irregular form and uncertain relations. the whole of these have not been studied in detail, but a sufficient portion of them have received careful examination to justify the drawing of certain conclusions from them. those which have been most studied lie in ohio, indiana, illinois, michigan, wisconsin, iowa and dakota. those of the first three states have been most carefully traced and their constitution is such as to give them the greatest discriminative value. to these our discussion will be limited chiefly.[ ] [ ] parts of these tracts were long since described by bradley of the illinois survey. (geol. surv. ill., vol. iv. p. ). collet of the indiana survey (an. rep. , p. ) and orton and hussey of the ohio survey (geol. surv. ohio, vol. iii., pp. , and ). the relationship of these tracts to morainic lines and to each other i worked out some years since (third an. rep. u. s. g. s. pp. , , ) but i owe many details and some important additions to my associate, mr. leverett. emerging from the dunes at a point north of the iroquois river in jasper county, northwestern indiana, a well characterized belt of surface boulders stretches westward to the state line, just beyond which it curves about to the south and then to the east, and re-enters indiana a little south of the northwest corner of benton county. it soon turns abruptly to the south and reaches the wabash river near the centre of warren county. the immediate valley of the wabash is thickly strewn with boulders from the point where the belt reaches it to the vicinity of west point on the western line of tippecanoe county. the uplands, however, do not give any clear indication of the continuity of the belt, and the connection is not altogether certain. there is an inner well-marked belt that branches away from this in the central part of benton county and runs southeasterly into the northwestern quarter of tippecanoe county, beyond which only scattered boulders occur, which leaves its precise connections also in doubt. but starting from west point, which is less than a dozen miles from the point where the two belts cease to be traceable with certainty, a well-defined belt, one or two miles wide, runs southeasterly across the southwestern corner of tippecanoe county and the northeastern quarter of montgomery county to the vicinity of darlington, beyond which its connection is again obscure, although boulders occur frequently between this point and the northwestern corner of brown county, where boulders are very abundant. so also, patches of exceptionally abundant boulders occur in the west central part of clinton county. these may be entitled to be regarded as a connecting link between the train which enters northwestern tippecanoe county and that of northwestern boone county, as scattered boulders of the surface type, but of not very exceptionally frequent occurrence, lie between them. however this may be, a belt of much more than usually frequent surface boulders stretches southeasterly to the vicinity of indianapolis, and probably connects with a very well-marked belt lying near the south line of the southeast quarter of marion county and in the northeastern part of johnson county. there is also a well-defined tract in southeastern hendricks county, running east and west, without evident connection with the foregoing tracts, though it may be the equivalent of the darlington belt. there is also a somewhat unusual aggregation in the form of irregular belts in southeastern johnson county, in the vicinity of nineveh, and in southern shelby county. the belt south of indianapolis is probably to be correlated by scattered boulders only slightly more abundant than those of the adjacent region, but of the surface type, stretching northeasterly to near the center of the west half of henry county, where a well-marked belt again sets in. from this point the tract runs northeasterly nearly to the north limit of the county, where it turns easterly and runs in the vicinity of the line between randolph and wayne counties to near the ohio line, where it curves to the southeast entering ohio near the northwest corner of preble county. in its southeasterly course across that county it is phenomenally developed as has been well shown by the descriptions of professor orton. soon after entering montgomery county it curves about to a northeasterly course, and crossing the great miami river, a few miles above dayton, holds its northeast course across the southeastern part of miami county, the northwestern part of champaign county, and thence on to about the center of logan county, where it curves about and runs in a direction a little east of south to near the southeast corner of champaign county, beyond which it ceases to be a specially notable phenomenon. in the region between the wabash and kankakee rivers, in northern indiana, there are numerous tracts of irregular form over which surface boulders in phenomenal abundance are scattered. these are particularly noticeable in southern jasper county; in the vicinity of wolcott, monon and chalmers in white county; near star city in pulaski county; in the southeastern corner of stark county, and very generally along the great interlobate moraines, lying parallel with the eel river, and some others of the saginaw glacial lobe. these are so associated with the inter-tangled morainic phenomena of that region as not to admit of convenient and brief description in their genetic relationships. the well-defined tracts have a most significant distribution. the first part described is associated with the terminal moraine that marked the margin of a lobe of ice that moved westward along the axis of the iroquois basin to a point a few miles beyond the indiana-illinois line. the portion that runs southward to the wabash is associated with the moraine that follows the same course, and runs at right angles over the older moraines of the lake michigan lobe. the tract in tippecanoe and montgomery counties, that in south marion county, and that in henry and randolph counties, in the eastern part of the state, are associated with the terminal moraines that form a broad loop with the west white river basin lying in its axis. in western ohio the belt is intimately associated with a moraine that bordered the miami lobe of the ice sheet, and the south-trending portion in eastern logan and champaign counties lies on the western margin of the scioto lobe. the relationship of these tracts to terminal moraines is very clear and specific. they constitute marginal phenomena of the ancient ice sheet. their distribution completely excludes their reference to floating ice, for they not only undulate over the surface utterly negligent of any horizontal distribution, but they are disposed in loops in crossing the basins of the region, and the convexities of these loops are turned down stream. these basins for the most part open out in southerly or westerly directions which makes it improbable that ice-bearing bodies of water occupied them. but if this were not fatal, certainly the fact that the convexities of the boulder belts are turned down stream and cross the centers of the basins is precisely contrary to the distribution they must have assumed if they were due to floating ice in bodies of water occupying the basins. i hold it, therefore, to be beyond rational question that these tracts were deposited as we find them by the margins of the glacial lobes that invaded the region. if these boulder belts were of the same nature as the average boulders of the till-sheets beneath them, then the simple fact of unusual aggregation might be plausibly referred to the accidents of gathering and deposition. but they are very clearly distinguished from the average boulders of the till by several characteristics. . they are superficial. sometimes they rest completely on the surface, sometimes they are very slightly imbedded, sometimes half buried, sometimes they protrude but a slight portion, and sometimes they are entirely concealed, but lie immediately at the surface. in all cases the aggregation is distinctly superficial. where they are buried, the burying material is usually of different texture and composition from the subjacent till, and appears to be distinct in origin from it. the superficiality of the tract is very obvious almost everywhere, and is especially so in regions where the subjacent till is of the pebble-clay rather than boulder-clay order, for the comparative absence of boulders below emphasizes the contrast. throughout most of the region the subjacent till is not of a very bouldery type, so that the distinction is generally a marked one. . the boulders of the belts are almost without exception derivatives from the crystalline terranes of canada. those of the great tract especially under consideration were derived from the typical huronian rocks of the region north of lake huron, and from granitic and gneissoid rocks referable to the laurentian series of the same region. these last, however, cannot be sharply distinguished from the granitic rocks derived from other parts of the laurentian terrane. the huronian rocks are very easily identified because of the peculiarities of some of the species. among these the one most conspicuously characterized is a quartz-and-jasper conglomerate. the matrix is usually a whitish quartzite. this is studded with pebbles of typical red jasper and of duller rocks of jasperoid nature, which grade thence into typical quartzite pebbles. with these are mingled crystalline pebbles of other varieties. another peculiar erratic comes from the "slate conglomerate" of logan. it consists of a slaty matrix through which are scattered rather distantly pebbles of granitic, quartzitic and other crystalline rocks. this is one of the forms of the "basal conglomerate" of irving. other varieties of this "basal conglomerate" are present. in addition to these very peculiar rocks, a quartzite of a very light greenish semi-translucent hue has a wide distribution along the tract. it is readily distinguishable from the numerous other quartzites of the drift of the interior. some years since, on returning from my first field examination of a portion of this belt, i sent a typical series of chips from the characteristic erratics to professor irving, who had recently returned from the study of the original huronian region. he returned a suite of chippings that matched them perfectly throughout, all of which were taken _in situ_ in the region north of lake huron. among the boulders of the belt are occasionally found specimens of impure limestone or of limy sandstone that might perhaps be referred doubtfully to some member of the paleozoic series; but on the other hand, might with equal or greater probability perhaps be referred to the similar rocks of the huronian series. these are quite rare, never forming, so far as my observations go, as much as one per cent. of the series. in the several definite enumerations made to determine the percentage of the doubtful specimens, the result never exceeded a fraction of one per cent. in the most extensive enumeration the result was about one-half of one per cent. aside from these doubtful specimens there are practically no boulders in the belts that can be referred to any of the paleozoic rocks that intervene in the miles between the parent series north of lake huron and the tract over which the boulders are now strewn. occasionally there may be seen erratics from the paleozoic series at or near the surface, but they are not usually so disposed on the surface as to appear to be true members of the superficial boulder tract. there is, therefore, the amplest ground for the assertion that these boulder tracts are of distant derivation, and that they are essentially uncommingled with derivatives from the intermediate region. . the boulders of this series are much more angular than those of the typical till sheets. some of them, indeed, are rounded, but the rounding is generally of the type which boulders derived by surface degradation and exfoliation present. they rarely have the forms that are distinctively glacial. quite a large percentage are notably angular, and have neither suffered glacial rounding nor spherical exfoliation. some few are glacially worn and scratched, but the percentage of these is small. the tracts therefore present these four salient characteristics: ( ) the boulders are derived from distant crystalline terranes ( to miles) and are essentially uncommingled with rock from the intervening paleozoic terranes; ( ) they are essentially superficial, and the associated earthy material has a texture differing from that of the subglacial tills; ( ) they are notably angular and free from glacial abrasion, except in minor degree; ( ) the tracts are so associated with terminal moraines and so related to the topography of the region, that there is no rational ground for doubt that the boulders were borne to their present places by the glaciers that produced the correlative moraines. in contrast to these superficial boulder formations, the till sheets below are made up of a very large percentage of glacial clay whose constitution shows that it was produced in part by the grinding down of the paleozoic series. in this are imbedded boulders and pebbles that were derived from the paleozoic series as indicated by their petrological character, and, in many instances, demonstrated by contained fossils. while a small part of the boulders contained in the till are angular or but slightly worn, the larger part are blunted, bruised, scratched and polished by typical glacial action. this obvious grinding of the boulders, taken in connection with the clay product resulting from the grinding, affords a clear demonstration that the deposit was produced at the base of the ice by its pushing, dragging, rolling action. the two formations, therefore, stand in sharp contrast; the one indicating the passive transporting action of the ice in bearing from their distant homes north of the lakes the crystalline boulders and dropping them quietly on the surface, the other indicating the active dynamic function of the ice in rubbing, bruising and scoring the material at its base. the one seems to me a clear instance of englacial and superglacial transportation; the other an equally clear example of subglacial push, drag and kneading. now if it were the habit of an ice-sheet of this kind to carry material from its bottom to the surface by internal movement, it would seem that the distance of to miles which intervened between the source of the crystallines and the place of their deposit would have furnished ample opportunity for its exercise, and that there would have been commingled with the englacial and superglacial material many derivatives from the intermediate region, and these derivatives should have borne the characteristic markings received by them while at the base of the ice. the very conspicuous absence of such commingling, and the absence or phenomenal rarity of anything that even looks like such a commingling, appears to me to testify in quite unmistakable terms to the distinctness of the methods of transportation. in view of the great territory over which this particular belt is spread, and the greater territory which is embraced in the other tracts not here specially considered, there is left little ground for doubt that this distinctness of englacial from basal transportation was a prevailing fact and not an exceptional one. this is supported by concurrent evidence derived from the territory west of lake michigan. this territory unfortunately does not bear erratics that have equally distinct characteristics, but, so far as my observation goes, the phenomena are alike throughout. i am therefore brought to the conclusion that, in the interior at least, there was no habitual lifting of boulders from the base of the ice sheets to the surface, nor any habitual commingling of basal with englacial and superglacial material, except, of course, as it took place by virtue of the falling of the latter through crevasses to the base, and by mechanical intermixture of the two at the edge of the ice. the amount of englacial till under this view is little more than that which was lodged in the body of the ice in its passage over the knobs and ridges of the hilly and semi-mountainous regions of the north. to this is perhaps to be added occasional derivatives from the more abrupt prominences of the paleozoic region and the superficial dust blown upon the ice from the surrounding land, which was probably the chief source of the silty material intermingled with the superficial boulders. the total amount is thus quite small, though important in its significance. the eskers and kames of the region are made up of derivatives from the basal material as shown by ( ) the local origin of the material in large part, ( ) the mechanical origin of the sands and silts, ( ) the not infrequent glacial markings of the pebbles and boulders, and ( ) the disturbed stratification of the beds.[ ] if i am correct in respect to the kind and amount of the englacial and superglacial material, it is obvious that eskers and kames, such as are found in the interior, could not be derived from englacial or superglacial sources. the term englacial as here used does not include such materials as may be lodged in the basal stratum of the ice and brought down to the actual bottom by basal melting. [ ] see "hillocks of angular gravel and disturbed stratification," am. jour. sci. vol. xxvii., may , pp. - . the conclusions drawn from the phenomena of the plains of the interior are not necessarily applicable to more hilly or mountainous regions. =t. c. chamberlin.= =_studies for students._= distinct glacial epochs, and the criteria for their recognition.[ ] [ ] read before the american geological society at ottawa, dec., . i. =introduction.= it has long been evident that writers on glacial geology are not at one concerning some of the important questions which underlie the interpretation of the history of the glacial period. certain recent publications have served to emphasize the differences between them. there are two questions, at least, concerning which there must be agreement, or at any rate a common understanding, before existing differences can be eliminated or justly evaluated. when the answers to these questions have been agreed upon, or when the positions of the contending parties are clearly understood, it may be found that some of the apparent antagonisms have no better basis than differences in definition. stated interrogatively, the two questions referred to are these: . what constitutes a glacial epoch as distinct from other glacial epochs? and . what are the criteria for the recognition of distinct glacial epochs, if such there were? ii. =the idea of a glacial epoch.= it is conceivable that, after the development and extension of a continental ice-sheet, it might be wholly wasted away. the maximum extension of such an ice-sheet would mark the culmination of a glacial epoch. if subsequently another ice-sheet of considerable dimensions were accumulated, its development and extension would constitute a second glacial epoch. these successive ice-sheets might be so related to each other in time, in position, and in the sequence of geological events, as to be regarded as separate epochs of the same glacial period.[ ] on the other hand they might be so widely separated from each other in time, in position, and in the sequence of geological events, as to make their reference to separate glacial periods more appropriate. in any case their separation would be sufficiently marked to necessitate their reference to separate ice epochs. so far we believe there would be no disagreement. [ ] the terms period and epoch are here used in the sense in which they have been used most commonly in the literature of glacial geology in the united states. if, instead of entirely disappearing, the first ice-sheet suffered great reduction of volume and area, and if this reduction were followed by a second great expansion of the ice, might the time of such expansion be regarded as a second glacial epoch of the common glacial period? to this question, too, as thus stated, we apprehend there would be but one answer, and that affirmative. it seems certain that the edge of the continental ice-sheet was subject to more or less extensive oscillations, as are the ends of glaciers and the edges of ice-sheets to-day. how much of an oscillation is necessary, and under what attendant conditions must it take place, in order that the recession of the ice-edge shall mark an interglacial and its re-advance a distinct glacial epoch? when the question takes this specific form, and when inquiry is made concerning the quantitative value of the different elements entering into the problem, we reach the battled ground. it is the battled ground, partly because it is the ground of misunderstanding. it is the ground of misunderstanding, partly because glacialists are not agreed as to the meaning of certain terms in common use by them. four elements seem to enter into the idea of an ice epoch as distinct from other ice epochs. these are ( ) the distance to which the ice retreated between successive advances; ( ) the duration of the retreat, or the time which elapsed between successive ice extensions; ( ) the temperature of the region freed from ice during the time between maxima of advance; and ( ) the intervention between successive advances, of changes interrupting the continuity of geological processes. ( .) it would be arbitrary to name any definite distance to which the ice must recede in order to constitute its re-advance a distinct ice epoch. it would be not so much a question of miles as a question of proportions. considering this point alone, we presume it would be agreed that an ice-sheet should have suffered the loss of a very considerable proportion of its mass, and that it should have dwindled to proportions very much less than those subsequently attained, before its re-advance could properly be called a separate glacial epoch. to be specific, if the north american ice-sheet, after its maximum extension, retreated so far as to free the whole of the united states from ice, we should be inclined to regard a re-advance as marking a distinct ice epoch of the same glacial period, if in such re-advance the ice reached an extension comparable with that of the earlier ice-sheet. especially should we be inclined to refer the second ice advance to a second glacial epoch, if it, as well as the preceding retreat, were accompanied by favoring phases of some or all the other three elements entering into the notion of a glacial epoch. in this statement we do not overlook the fact that a northerly region--as labrador or greenland--might be continuously covered with ice throughout the time of the two glaciations of the more southerly regions. but this is not regarded as a sufficient reason for discarding the notion of duality. greenland has very likely been experiencing continuous glaciation since a time antedating that of our first glacial deposits. the renewal to-day of glaciation comparable in extent to that of the glacial period would certainly be regarded as a distinct glacial epoch, if not a distinct glacial period, even though greenland's glaciation may not have been interrupted. scandinavia and switzerland have probably not been freed from ice since the glacial period. their snow and ice fields are probably the direct descendants of the ice fields of the glacial period. an expansion of the existing bodies of ice in these countries to their former dimensions, would constitute a new glacial epoch, if not a new glacial period. analogous subdivisions in pre-pleistocene formations have been frequently recognized. ( ) the application of the time element is hardly susceptible of quantitative statement. we are inclined to think that it would be generally agreed that, with a given amount of recession of the ice, its re-advance would be more properly regarded as a distinct glacial epoch if the interval which had elapsed since the first advance were long. whether a longer time between the separate advances might reduce the amount of recession necessary in order to constitute the second advance a second epoch, we are not prepared to assert; but we are inclined to think it might. ( ) the third element is perhaps somewhat more tangible than the second. if, during the retreat of the ice, the climate of a region which was twice glaciated became as temperate as that of the present day in the same locality, we should be inclined to regard the preceding and succeeding glaciations as distinct ice epochs, especially if the intervening recession were great and its duration long. unfortunately for simplicity and ease of determination, there are difficulties in determining with precision how far the ice retreated between successive maxima of advance, how long the interval during which it remained in retreat, and the extent to which the climate was ameliorated, as compared with that which went before and that which followed. ( ) if changes of any sort which interrupt the continuity of geological processes intervened between successive maxima of advance of the ice, the separation of the later advance from the earlier, as a distinct ice epoch, would be favored. how great the intervening changes should be in order to constitute the re-advance a distinct ice epoch, is a point concerning which there might be difference of opinion. but it is altogether possible that such changes might intervene as alone to give sufficient basis for the separation. orographic movements, resulting either in continental changes of altitude or attitude are among the events which might come in to separate one ice epoch from another. changes of this sort have often furnished the basis for the major and minor divisions of time in other parts of geological history, so that there can be no question as to their adequacy, if they were of sufficient magnitude. we hold that the intervention of orographic or other important geologic changes might reduce to a minimum the amount of recession, the duration of the recession, and the warmth of the intervening climate necessary to constitute the separate ice advances separate ice epochs. the absence of great orographic or other changes in glaciated regions between successive advances of the ice would be no proof that such advances should not be regarded as separate epochs. divisions of equal importance have often been made without evidence of such changes. from the foregoing discussion, brief as it is, it will be seen that within certain narrow limits the definition of a glacial epoch, as distinct from other glacial epochs, must be more or less arbitrary. it is less important that an arbitrary definition should be accepted, than that the same meaning should be attached to technical terms in common use among geologists. in the interest of harmony and of a common understanding, and without the violation of any truth of science, we believe it would be well if the conception of a glacial epoch, as framed by those who are our leaders in position and in fact, were made the basis for our usage of the term. iii. =the criteria of distinct glacial epochs.= if there have been differences of opinion concerning the nature of ice epochs, as distinct from each other and from ice periods, there has been a failure to adequately apprehend the nature, the extent, and the meaning of the real criteria on which the final recognition of separate ice epochs, if such there were, must be based. such criteria are several in number. they are of unequal value. in some instances a single one of them might be quite sufficient to establish the fact of two ice epochs. in other cases, single criteria which might not be in themselves demonstrative, have great corroborative weight, when found in association with others. in all cases, much discretion must be used in the interpretation of these criteria. they may be enumerated under several specific heads. ( ) _forest beds._ beds of vegetal deposits or old soils are frequently found between layers of glacial drift. this is one of the criteria most commonly cited, because it is of common occurrence and easy of recognition. the advocates of the unity of the glacial period maintain that such beds of organic matter might become interbedded with morainic debris during minor oscillations of the ice's edge. the phenomena of existing glaciers make it evident that forest beds or soils might be enclosed by the deposits of an oscillating ice edge. by repeated oscillations of the ice's edge during the general retreat of the ice, such vegetal beds might become interstratified with glacial drift more or less frequently over all the area once covered by the ice, and from which it has now disappeared. the mere presence of vegetable material between beds of drift is therefore no proof of distinct ice epochs. this does not destroy the value of the vegetal beds as a criterion for the recognition of distinct ice epochs, but it makes caution necessary in its application. it does not follow that, since _some_ inter-drift forest-beds do not prove interglacial epochs, _none_ do. the question is not how forest-beds might originate, but how existing forest-beds did originate. where the plant-remains found in the relations indicated are so well preserved as to make identification of the species possible, we have a means of determining, with some degree of accuracy, the climatic conditions which must have obtained at the place where the plants grew during the time of their life. if these interbedded plant-remains are of such a character as to indicate a temperate climate, we can not suppose that they grew at the immediate edge of the ice, and therefore that they were buried beneath its oscillating margin. to be specific, if the inter-drift plant remains in any given locality of the area once covered by ice are such as to indicate a climate _as warm as the present in the same locality_, the ice must have receded so far to the northward that its re-advance might, in our judgment, appropriately be regarded as a separate ice epoch. it has been suggested in opposition that temperate conditions may obtain even up to the edge of the ice, and that interbedded vegetal remains indicating temperate climate do not prove any considerable recession of the ice. the phenomena about existing glaciers have been appealed to in support of this demurrer. but the objection is not well taken. the climatic conditions which obtain about the borders of small, local glaciers, are not a safe guide as to climatic conditions which obtained about the margin of a continental ice-sheet, any more than the climatic conditions which obtain about a small inland lake are a safe criterion as to the climatic conditions about a sea-coast. the general principles of climatology, as well as specific facts concerning plant distribution, seem to us to indicate that the climate about the border of a continental ice-sheet must have been arctic. it is evident that the greater the distance north of the overlying drift remains of temperate plants are found, the more conclusive becomes the evidence. plant remains indicating temperate climate at the very margin of the drift sheet which overlies them, would be less conclusive than similar evidences one hundred miles to the northward. it might be difficult to prove in any given instance that the ice which deposited the drift overlying plant remains advanced one hundred miles, or any other specific distance, south of any particular underlying forest bed. if the forest bed were continuous for the whole distance, the case would be clear. it would also be conclusive if the continuity of the drift overlying a forest bed at any point with that of a remote point to the south, could be demonstrated. in spite of these difficulties in its application, the vegetal beds constitute a valuable criterion in making the discriminations under consideration, when they are properly applied. under proper circumstances the criterion may be conclusive when taken alone, and it may have corroborative significance when not itself conclusive. the absence of forest beds and of all traces of vegetal deposits whatsoever between beds of drift, is no proof of the absence of recurrent ice epochs, since the second advance of the ice might have destroyed all trace of the preëxistent soil and its vegetal life. it is always possible, too, that such beds exist, even if they have not been discovered. it would have been anticipated that they would not be abundant, or wide spread. the absence of forest beds is therefore at best no more than negative evidence. ( ) _remains of land animals._ bones of mammalia or remains of other land animals, occurring in relations similar to those in which forest beds occur, may have a like significance. their value as a criterion of separate glacial epochs is subject to essentially the same limitations as forest beds. ( ) _inorganic products formed during a time of ice recession._ the recession of the ice after a maximum of advance would leave a land surface more or less affected with marshes and ponds. in such situations, bog iron ore might accumulate, if conditions were favorable. such ore beds, buried by the drift of a later ice advance, would have a significance comparable to that of forest beds, except that they would give less definite information as to climate, and would be correspondingly less trustworthy. should such ore beds be found in such relations as to prove that the underlying and overlying bodies of drift were deposited by ice sheets which extended great distances further south, their significance would be enhanced. from the thickness of the ore beds some inference might be drawn as to the length of time concerned in their accumulation. but because of the variable rate at which bog ore may accumulate, such inference should be used with caution. concretions of iron oxide might be formed in the marshes or in ill-drained drift areas where accumulations of greater extent were not made. a subsequent incursion of the ice might incorporate these nodules with its drift, wearing and striating them as other stones, and depositing them as constituent parts of the later drift. such iron nodules in the later drift would mean a recession and re-advance of the ice with some considerable interval between, although not necessarily an interval sufficiently warm or long to be regarded as an interglacial epoch.[ ] calcareous concretions, like those of the loess, would possess a like significance, in like relations. while in themselves these inorganic products of a time of ice recession might fail to be conclusive of separate ice epochs, they might have much corroborative significance when associated with other phenomena. an inter-till iron ore bed, associated with a forest bed which indicated a warm climate, would be most significant. [ ] this point concerning iron nodules was suggested to the writer by mr. w. j. mcgee. the absence of knowledge of ore beds between sheets of till, and the absence from an upper bed of till of concretions of iron and lime carbonate formed during a recession of the ice, would be no proof that interglacial epochs did not occur. these products were probably formed in relatively few localities. they stood good chance of destruction at the hands of the returning ice, and they may exist, where they have not been discovered, or where their significance has not been understood. their absence is at best no more than negative evidence. ( ) _beds of marine and lacustrine origin._ if between beds of glacial drift there be found beds of lacustrine or of marine origin, such beds would indicate a recession of the ice during their time of deposition. their position would be a minimum measure of ice recession. if such lacustrine beds contain organic remains, they will bear testimony concerning the climatic conditions which existed where they occur, at the time of their deposition. if the fossils in such beds denote a temperate climate, or a climate as mild as that of the present day in the same region, the ice must have receded so far to the northward as, in our judgment, to constitute its re-advance a distinct ice epoch. this line of argument may be even stronger than that drawn from remains of terrestrial life, since the ice would probably affect the temperature of the sea to greater distances than that of the land, and affect it to a greater degree within a given distance. the argument becomes stronger the further north the inter-drift marine and lacustrine deposits occur, since the ice must always have receded to a position still further north. if marine or lacustrine beds lying far north of the later ice limit contain proof of temperate climate, the argument becomes conclusive. the absence of marine and lacustrine deposits between beds of drift, would be no proof that interglacial epochs did not occur. lacustrine beds could be made only where there were lakes, and lakes would be the exception rather than the rule. marine beds in similar positions would rarely be known, except where a definite succession of changes of level has taken place. both classes of deposits, if once formed, would be subject to destruction by the over-riding ice of a later epoch, if such there were. neither would be likely to be preserved at all points where formed, and both may exist at many points where their existence is not known. the absence of these beds is at best no more than negative evidence. ( ) _beds of subaërial gravel, sand and silt._ layers of stratified drift between layers of ground moraine are of common occurrence in many regions. under ordinary conditions their existence is not regarded as evidence that the underlying and overlying tills are to be referred to separate ice epochs. but it is conceivable that beds of stratified drift may, under the proper circumstances and relations, be strong evidence of separate ice epochs. the last stages of ice work in the glacial period were accompanied, in many regions, by the deposition upon adjacent land surfaces, of extensive bodies of gravel and sand, washed on beyond the ice by waters issuing from it. except in valleys through which strong currents coursed, such deposits were apparently not carried far beyond the edge of the ice. but as the edge of the ice withdrew to the northward, sand plains may have extended themselves in the same direction, by additions to their ice-ward faces. it is conceivable that the process of subaërial plain building at the edge of a receding phase of ice, might be carried so far under favorable circumstances, as to result in the construction of plains of great extent. in this event, a subsequent ice-advance might overspread such plains in such wise as to bury, without destroying them, though such a course of events would certainly be exceptional. in order to constitute the interstratified gravel and sand evidence of separate ice-epochs, its continuity for great distances between beds of till, and in the direction of ice movement, would need to be demonstrated. in themselves, these beds, under the conditions indicated, would simply be a minimum measure of the amount of ice recession between the deposition of the underlying and overlying bodies of till. it is hardly likely, though possible, that the continuity of interbedded gravel and sand could be proved for a sufficient distance north of the southern limit of the less extensive bed of ground moraine, to alone constitute evidence of a recession of ice great enough to make it necessary to refer its re-advance to a new epoch. beds of silt in like relations, deposited by waters beyond the edge of the ice, would have a like significance so far as the question here under consideration is concerned. such beds of stratified drift might sometimes have corroborative value when their testimony, taken by itself, is inconclusive. if, for example, their surfaces are marked by forest beds, and especially by forest beds whose plants denote a warm climate, the association becomes most significant. in view of what has been said, it is evident that the absence of beds of subaërially stratified silt, sand, and gravel, between beds of till can not be brought in evidence against separate ice epochs. it would rarely be true that topographic and hydro-*graphic conditions would make possible the construction of plains of sufficient extent to serve as criteria for the purpose here indicated, and few of those formed would escape such a degree of destruction as to leave them demonstrably continuous. there is also the further possibility that such beds exist, even though their continuity be not known. to prove the continuity of a buried bed of stratified and incoherent drift, even if it existed, would be a most difficult task. ( ) _differential weathering._ if, after covering a given region, the ice retreated, the drift which it left in the area which it previously covered would be subject to oxidation, leaching and disintegration. the depth to which this oxidation, leaching and disintegration would extend, would be dependent upon the length of time during which the drift was exposed, and upon the climate which affected the region during its exposure. the longer the exposure and the warmer the climate, the deeper would the weathering extend. if, subsequently, the ice extended over the same region, it might, in some places, override and bury the old surface without destroying it. the earlier oxidized and leached drift would thus come to be buried by the newer, unoxidized, unleached drift. if, therefore, beneath the newer drift of any given locality there be found a lower drift, the surface of which is oxidized and leached to a considerable depth, the evidence is strong that the lower drift was exposed for a long period of time before the upper drift was deposited upon it. within certain limits a similar result might be brought about, it is true, if the ice, after having reached a certain maximum stage of advance, were to retreat for a short distance only and there remain for a very long period of time. a subsequent minor advance might bury the oxidized surface of the drift beyond the position of the long ice-halt. under these conditions, the climate which would have obtained in the area of the drift exposed during the minor retreat would have been cold, and oxidation, leaching, and disintegration would have proceeded slowly. if they reached considerable depths, the time involved must have been very long. if this surface of oxidized and leached and disintegrated drift were found to reach far to the northward beneath the layer of newer and upper drift, it would indicate a great recession of the ice. we maintain that if it were found sufficiently far north of the margin of the overlying drift, and if its depth were sufficiently great, extending well down below any possible accumulation of superglacial till, it might be a positive criterion of so great a recession of the ice, protracted through so great an interval of time, as to constitute its new advance a separate ice epoch. there is much reason to believe that the soil developed under the influence of a warm climate differs in some respects from one developed from similar material under other conditions. the well-known fact that red and reddish soils are especially characteristic of low latitudes and warm climates is significant. if therefore a soil developed on the surface of one sheet of drift and buried by another, be found to possess, in addition to unmistakable marks of long exposure, the peculiar marks which seem to be characteristic of soils developed under high temperatures, the argument gains in strength. this argument from oxidation and weathering has another application. if in a later advance, following a protracted recession, the ice-sheet failed to reach the limit of its earlier advance, there would remain an area of drift deposited by the first ice-sheet, outside the drift deposited by the later. now if the time interval between these two advances was great, and especially if during this interval the climate was mild, the oxidation and weathering of the older drift surface would be markedly different in degree from that of the newer. if, under these circumstances, the surface of the older sheet were found to be weathered and oxidized and reddened up to the border of the newer drift sheet, and if here there were found to be a sudden change in the character of the surface of the drift so far as depth and degree of oxidization and weathering is concerned, we should have strong evidence that the one sheet of drift was much older than the other. the statement sometimes urged that the drift which was deposited near the edge of the greatest ice advance would be largely made up of the residual materials which occupied the surface invaded by the ice, would not meet the case. for if it be granted that this statement is qualitatively good, we should find the greatest degree of weathering and oxidation at the extreme margin of the drift, and it should be found to be less and less on receding from this margin. there would in this case be no sudden transition from a deeply weathered and oxidized surface, to one which is fresh and unoxidized, along a definite line. we maintain that if the whole of the drift deposits are referable to one epoch, there should be no sudden transition in the surface of the drift from that which is deeply weathered to that which is not, the one surface being separated from the other by a definite and readily traceable line. it has been urged against the criterion of differential weathering that superglacial material is or may be thoroughly oxidized before its deposition, and that a layer of oxidized drift between layers of till may be no more than superglacial debris deposited during a minor recession of the ice.[ ] we believe that this attempt to eliminate the value of this criterion rests partly on an exaggerated idea concerning the amount of superglacial material, but more especially on a failure to apprehend the real meaning of the argument for the validity of the criterion, and upon a failure to note the limitations imposed upon it by its advocates. it is not affirmed that a layer of oxidized drift between beds of unoxidized drift is _per se_ proof of two glacial epochs; but it is affirmed that if such layer of weathered drift can be shown to extend far below any possible superglacial till, into the subglacial till below, in such wise as to indicate that it is the result of subaërial exposure in a warm climate subsequent to its deposition and prior to the deposition of the overlying till, it constitutes the best possible evidence of an interglacial epoch, especially when accompanied by the corroborative testimony of other criteria. it is further affirmed that if the second sheet of drift failed to reach the limit of the first, and if the drift which was deposited by the first and never covered by the second ice-sheet, is more thoroughly and more deeply weathered than that deposited by the second, and especially if the two types of drift surface meet along a definite and readily traceable line, the argument becomes, in our judgment, irrefragable. in its application, this criterion would be infallible only in the hands of one who could distinguish between superglacial and superglacially oxidized material on the one hand, and material subaërially weathered after its deposition, on the other. [ ] this point was urged at the reading of the paper at ottawa, by prof. c. h. hitchcock, mr. upham, and others. in circumstances and relations where the weathering of the drift is not in itself conclusive, it might still have corroborative value in association with other lines of evidence. the absence of an oxidized and disintegrated zone of drift below a superficial layer which is not oxidized, would be no proof that there were not distinct ice epochs, since the ice of any later epoch, if such there were, might have planed off the surface of the drift left by its predecessor to the depth of the weathering. the preservation of such surfaces after a second ice invasion must be regarded as the exception rather than as the rule. there is always the possibility, too, that an oxidized and weathered zone marking the surface of an older drift sheet exists, where excavations have not opened full sections of drift to view. the absence of weathered zones of drift beneath the surface, or the absence of knowledge of their existence, is therefore at best no more than negative evidence. the absence of greater weathering of the drift outside the limit of the drift supposed to belong to a later epoch, would be positive evidence against the reference of the two sheets of drift concerned to different epochs. a specific part of the above line of evidence may be separately mentioned. one phase of weathering is the disintegration of boulders, and this is a point which can be readily applied even by those who are not geologists. if the boulders of one region are much more commonly disintegrated than those of another, and if the two regions are separated from each other by a well-marked boundary line, the inference lies close at hand that the boulders in the one case have been much longer exposed to disintegrating agencies than in the other. it is no answer to this argument to say that the materials lying at the very front of the drift deposits contain boulders which were derived from the disintegrated rock over which the ice has passed, and that they were therefore in a less firm state at the outset. in many cases these boulders have come from great distances, and coming from great distances they must have come in a firm and solid state, else they could not have suffered such extensive transportation, except indeed their position was superglacial throughout their whole journey. this argument has equal force when applied to the area covered by the two sheets of drift where two exist. if within the region of drift under investigation we find a surface layer of greater or less depth, the boulders of which are hard and fresh, and if beneath this we find another layer of drift, the stony material of which is largely disintegrated, at least in its upper parts, we have good evidence that the surface bearing the disintegrated boulders was exposed for a considerable length of time before the deposition of the overlying drift, which carries fresh boulders. since the disintegration of boulders is only one phase of weathering, the limitations of this argument are identical with those already noted in connection with the general argument from differential weathering. ( ) _differential subaërial erosion._ if the drift deposited by one ice-sheet were to be exposed for a considerable interval of time, and if the ice in its subsequent advance failed to reach the limit of its first invasion, the two areas should show different amounts of subaërial erosion, since the one has been exposed to the action of air and water much longer than the other. the line which marks the limit of the later ice invasion should be the line of more or less sudden transition from an area without, where stream erosion has been greater, to an area within, where stream erosion has been less. the point here made can not be met by the suggestion that the greater erosion of the outer area was effected by the water issuing from the ice which had retreated to the position now marked by the border of the area of the lesser erosion. so far as we know, such waters would be depositing, not eroding. furthermore, much of the erosion of the outer area would have such relation to drainage lines that waters issuing from the ice could never have reached the localities where it is shown. if the outer and older drift be found to have suffered ten times as much stream erosion as the inner and newer, it is fair to assume that it has been exposed something like ten times as long, if the conditions for erosion are equally favorable in the two regions. the argument has especial weight if it can be found that beneath the newer drift the surface of the older is such as to indicate that it was deeply eroded before the newer was placed upon it. the argument is stronger the farther from the margin of the newer drift such erosion on the surface of the underlying older drift can be proved to have taken place. in other words, if, in addition to the greater surface erosion of the older drift sheet as now exposed outside the limit of the newer drift, we find a notable unconformity between the newer and the older drift, and especially if this unconformity lie far enough north of the margin of the newer drift, the argument becomes conclusive. when differential erosion and drift unconformities are not in themselves conclusive, they may have great corroborative value in conjunction with differential weathering, forest beds, or other indications of separate ice epochs. the absence of observable unconformity between sheets of drift would be no proof that there were not distinct and widely separated ice epochs, since the later ice invasion might have so far modified the surface which it transgressed, as to destroy all patent evidences of unconformity. it would have been anticipated that distinct unconformities in the drift would be rare, even if there were distinct ice epochs, for the same reason that weathered zones and forest beds would be rare. but if the drift which lies outside a line supposed to mark the limit of a sheet of drift belonging to a later ice epoch, be not more eroded than that which lies within such line, the absence of greater erosion in the outer drift is positive evidence against the reference of the drift of the two areas to distinct ice epochs, if conditions for erosion in the two areas are equally favorable. ( ) _valleys excavated between successive depositions of drift._ a closely related, but not identical, point may be found in the extent of the valley excavations which can be proved to have taken place between the deposition of the earlier and later drift. we do not refer to valleys excavated in the drift especially, but to those excavated in other formations as well. if it can be shown, for example, that after the deposition of an earlier drift sheet, and before the deposition of a later, valleys were excavated which extended not merely into the drift itself, but far beneath the drift into the underlying rock, these valleys would be conclusive evidence of a long interval between the deposition of the two bodies of drift. the argument is of especial force when such excavations in the rock beneath the drift can be shown to have taken place at great distances within the margin of the newer drift. for valleys in such situations imply that the ice had receded at least as far to the north as they lie, during the interval between the two drift depositions, and may be so situated as to show that the ice had wholly left the drainage basin where they occur. the absence of evidences of deep valley excavations in any given region during a supposed interglacial epoch, is no proof that such interval did not exist. the conditions may not have been everywhere favorable for erosion within the limits of any narrowly circumscribed area, and the absence of interglacial valleys would be only negative evidence against an interglacial epoch. the absence of such evidence everywhere would bear against the existence of an interglacial epoch of much duration in such wise as to be more than negative evidence. ( ) _different directions of movement._ if, after its maximum advance, the ice suffered merely a minor recession and then remained stationary, or nearly so, for a time, the general direction of its movement in a subsequent advance would probably be essentially the same as in the earlier. but if, after its maximum advance, the ice receded to a great distance, and especially if it entirely disappeared, a subsequent ice-sheet might have a very different direction of movement, since its center of accumulation and dispersion might be very different. it is conceivable that this center might shift during the history of a single ice-sheet. in this case there should be a gradual change in the direction of ice movement, not an abrupt one. if, therefore, there be found one sheet of drift made by an ice movement in one direction, overlaid by another sheet of drift deposited by ice moving in a very different direction, with an abrupt transition between them, such drift sheets would be presumptive evidence of distinct ice epochs. an exception would need to be made in the case of drift sheets along the margins of confluent or proximate ice lobes. in such cases, if the one lobe temporarily secured the advantage of the other, drift beds formed by movements from opposite directions might be found in vertical succession, without being evidence of separate ice epochs. it is no part of the purpose of this essay to point out the difficulties which might arise in the application of this criterion of diverse directions of ice movements. it is possible that gradual changes in the direction of movement might leave records which would seem to indicate abrupt changes instead. this possibility makes care necessary in the application of the criterion, but does not destroy its value. when not itself conclusive, this criterion may be so associated with differential weathering, differential erosion, forest beds, etc., that their combined testimony makes but one conclusion possible. the absence of evidence of radically diverse directions of movement during the time of deposition of the various sheets of drift, would be no proof that there were not distinct epochs. in the first place, the movements of different epochs might be harmonious--a condition of things more probable than any other if the more common views of the causes of glaciation be correct. in the second place, if the movements were diverse, the deposits might still be so similar that their differentiation, when the one is buried, might not be easily made. in the third place, the later ice might have so far incorporated the older drift material with that which belonged more properly to it, as to have destroyed all definition between them. ( ) _the superposition of beds of till of different physical constitution._ after the retreat of an ice-sheet, the surface of the country thus discovered would be largely mantled with drift. this drift would serve to protect the underlying rock from disintegration. but where there was little or no drift, the rock surface would be subject to all the disrupting agencies which affect surface rocks. the same would be true of all rock surfaces bared by subaërial erosion after the disappearance of the ice. under these conditions, if a second sheet of ice invaded the region in question after it had been long exposed, it would find a surface prepared to yield large bowlders. the result would be the deposition of a new sheet of drift containing bowlders much larger than those which would have been proper to an ice-sheet overspreading a surface but recently abandoned. if, therefore, in the upper of two layers of subglacial till, bowlders of great size predominate, as compared with those of a lower homologous layer, they may be indicative of a great interval of time between the deposition of the upper and lower beds of drift. if the home of these bowlders be far north of the limit of the lesser sheet of drift, the distance, as well as the duration, of the ice retreat must have been great, and the reference of the two beds of till to distinct ice epochs would be favored. the case might be so strong as to make no other interpretation possible. where in itself inconclusive, this criterion would have corroborative significance. in its application, the discrimination of subglacial and superglacial till would be imperative. the absence of physical dissimilarity between superposed layers of subglacial till would not be proof of the absence of separate glacial epochs. the phenomena constituting the criterion could hardly be expected to be of common occurrence. they would never be obtrusive, and may easily have escaped attention where they exist.[ ] [ ] the th criterion, in the order here named, was suggested by mr. mcgee in the discussion which followed the reading of the paper at ottawa. ( ) _varying altitudes and attitudes of the land._ another line of argument has to do with the altitude and attitude of the land during the deposition of various members of the drift complex. if during the deposition of one part of the drift that part of the continent covered by the outer part of the ice was low, the drainage from it would be sluggish. if the deposits of this drainage persist to the present time, we may find in their character evidence of the nature of the drainage, and therefore of the attitude of the land. if at a later time of drift deposition the glacial drainage in the same region was more vigorous, the deposits made by the glacial streams would be correspondingly coarser. in these deposits, if they persist to the present day, we should find conclusive evidence of the swiftness of the streams. if it can be shown that during the deposition of one sheet of drift drainage was sluggish, and that during the deposition of a later body of drift the drainage was vigorous, these facts are evidence of an interval between the two times of drift deposition, sufficiently long to accomplish the corresponding changes in elevation or attitude. since such changes of altitude and attitude are generally believed to have been accomplished slowly, the interval must be believed to have been of considerable duration. it is true that continental altitudes and attitudes might change during a single epoch of glaciation. if the change thus brought about resulted in increased slope, the more sluggish drainage of the earlier part of the epoch would be gradually transformed into the more vigorous drainage of the later part. in this case, if the evidence of both the earlier sluggish drainage and of the later vigorous drainage remain, there should also remain the evidence of the intermediate stages. if the deposits representing the intermediate condition of drainage do not exist, while those representing both extremes do, there would be the best of reason for believing that the intermediate phases of drainage did not exist during a glacial epoch, but during an interglacial epoch, when streams were not handling glacial debris, and when they were eroding rather than depositing. the deposits of the slow and of the swift drainage might occur in such relations as to prove, beyond peradventure, that intermediate stages of _glacial_ drainage never existed. if the sluggish drainage accompanied the maximum ice invasion, while the vigorous accompanied a lesser, the evidence of the swift streams might be found far north of the southern limit of the earlier drift. the farther north of the outer border of the older drift the gravel representing the vigorous drainage of the later and minor ice-sheet occurs, the further the ice must have retreated before the change from the one type of drainage to the other was effected. on the other hand, the farther north of the limit of the later ice advance the sluggish drainage accompanying the earlier ice-sheet may be traced, the farther must the ice have receded before the changes resulting in vigorous drainage occurred. under certain relations, the retreat of the ice might be shown to have been great enough, before the orographic movements which altered the nature of the drainage, to constitute in our judgment, a re-advance a distinct ice epoch. if for example throughout the course of a long river whose basin was largely covered with ice, there be evidence that sluggish drainage obtained during the maximum ice advance, and during all stages of the ice retreat until the basin was free from ice, and if there be evidence of a vigorous glacial drainage in the same valley at a later time, with no gradations between the two types, we have proof positive of at least a great recession, and of a considerable elevation of the land after the ice had receded beyond the limits of the drainage basin and before it again reached it in its re-advance. we hold that these phases of glacial drainage deposits may be so related to each other, to the valleys in which they occur, and to more or less distinct bodies of glacier drift, as to prove so great a recession of ice between the diverse phases of drainage deposition, as to constitute the second advance a distinct ice epoch. the absence of evidence that the land stood at different elevations during different parts of the period of drift deposition, does not in any way militate against the theory of recurrent and distinct ice epochs. a constant attitude of the land is the thing to be assumed, until positive evidence to the contrary is adduced. ( ) _vigor and sluggishness of ice action._ if it can be shown that during one epoch of glaciation, we will say the epoch of maximum ice extension, the ice action was relatively sluggish, while during a later and minor advance its action was vigorous, the difference of action might be regarded as presumptive evidence of distinct ice epochs. evidence of the two phases of ice action here referred to are difficult of definition, but they have been independently noted by more than one glacialist. it is true that a forward oscillation of the ice edge might be more forceful than an earlier forward movement which might have reached a greater extension. in itself, therefore, this line of evidence can not be regarded as possessing great value. it has been indicated that under certain circumstances, and in certain relations, some of the foregoing criteria, taken singly, may be conclusive of glaciations so distinct from each other, as to make their reference to separate epochs proper. but where the facts and relations which constitute one of the criteria are found, the facts and relations constituting one or more of the others are likely to be found as well. where two of the foregoing criteria are found to be coexistent, their joint force is greater than that of either one. if neither one be absolutely conclusive, the two may still be, since the one may exactly meet the deficiency of the other. if three or more concurrent lines of evidence exist in any locality, the case is still further strengthened. we maintain that several of the foregoing criteria may be so related to each other and to the formations concerned, as not only to make the recognition of separate ice epochs proper, but to make the failure of such recognition altogether unscientific. even when a single line of evidence, or when double, or triple, or quadruple lines of evidence are not absolutely conclusive in ruling out every conceivable technical escape from the conclusion that there were separate ice epochs, their cumulative and corroborative force may still be such as to carry conviction scarcely less positive than that which mathematical demonstration would afford. in the nature of the case not all of these various lines of evidence could be expected to be found in any one locality, or perhaps in any one limited geographic area, but where one occurs, some or all of the others are liable to be found under favoring circumstance. the number of criteria, and the great extent of area where they may hope for application, afford great possibilities. from the foregoing discussion, it will be readily seen that the nature of the criteria and the limitations imposed upon their application by the difficulty of proving stratigraphic continuity in such a formation as the drift, necessitate the greatest care in their use, and reduce the value of hasty and inexpert conclusions to a minimum. iv. =areas where the criteria find readiest application.= the foregoing criteria find their readiest application in regions where a later sheet of drift, suspected of belonging to a later ice epoch, failed to reach the border of an earlier sheet of drift, suspected of belonging to an earlier ice epoch. the st, d, d, th, th and th as enumerated above, find their application wholly within the area affected by the drift of the separate epochs, if such there were. while within this general area they may be looked for at any point, they are likely to be of rare occurrence, except along a somewhat narrow belt, say to miles, adjacent to the border of the lesser ice advance. the conditions for their occurrence and detection are greatly favored if the lesser drift sheet be the later. the th, th, th and th criteria might hope for application within the same belt, but especially along a narrow zone on either side of the margin of the later drift sheet. it is along this zone that the types of surface are thrown into sharpest contrast, both as to material and topography. the th and th criteria have still wider limits of application, both within and without the border of the lesser ice advance. =rollin d. salisbury.= =_editorials._= it is the chief function of the national, state and provincial geological surveys to bring forth the great concrete facts relative to the structure and resources of their several fields. within their special domains they also do an important work in the correlation of structures and formations, in the systematic aggregation of the facts, in the organizing of results, and in the development of the fundamental principles of geological science. to some extent they are permitted to do this beyond their own fields, but in the main the boundaries of these fields are the limits of their coördinations. they therefore leave a great function to be performed by some other agency in the coördination of interstate, international, and intercontinental factors. they are also restrained by their relationships to a somewhat too narrowly utilitarian public from devoting much direct attention to the solution of the deeper and broader problems that constitute the soul of science, though their contributions bear upon these in the most radical and important way. in the primary work of systematic observation, and the development of the immediate conclusions that spring therefrom, these surveys surpass all other agencies in the value of their contributions to the growth of the science, but in the secondary and ulterior work of correlation, in the synthetic aggregation and organization of results, and in the analytical and philosophical treatment of the whole, they need to be supplemented by agencies whose facilities and limitations lie in other lines, agencies whose relations and dependencies are complementary in nature. this secondary and ulterior work, in some degree, has been done by individual master students of systematic and philosophical geology, but to a very great extent it has not been done at all. it is a function which properly falls to universities, if the universities can only rise to meet it; for it is the function of universities, in the larger modern view, not only to rehearse science, nor merely even to educate young geologists, important as that is, but to develop science for science's own sake, and for its own inherent and permanent utilities as distinguished from its immediate applicabilities. to fulfill this function they must not only realize and appreciate it, but they must be equipped for field and experimental work, as well as library and laboratory study. ideal correlations and academic systematizing are as apt to be hindrances as helps to the progress of science. while a few of the great universities of this country and europe have made notable advances in these directions, the universities are, on the whole, far behind the great surveys in the performance of the work which properly falls to them. this is due not so much to a lack of appreciation of the function as to the lack of facilities. with the development of this higher function of the universities there goes a coördinate function for a university journal of geology, a journal whose special efforts shall be devoted to promoting the growth of systematic, philosophical, and fundamental geology, and to the education of professional geologists. no part of the wide domain can wisely be neglected by any journal, but there seems to be an open field for a periodical which specially invites the discussion of systematic and fundamental themes, and of international and intercontinental relations, and which in particular seeks to promote the study of geographic and continental evolution, orographic movements, volcanic coördinations and consanguinities, biological developments and migrations, climatic changes, and similar questions of wide and fundamental interest. this field is not likely to be successfully cultivated except by a systematic endeavor, pursued through a period of years, to bring together the latest and best summations of the results attained in the several national fields in a common medium, where they can be compared and discussed, and where tentative correlations will suggest themselves, out of which, in turn, working hypotheses will naturally spring, leading on to such direct investigations as the nature of each question invites. it would be presumptuous to assume that the =journal of geology= can cultivate with more than very partial success this field, but it especially invites contributions of this class. another phase of geology which is thought to stand in much need of active cultivation is found in the clear and sharp analysis of its processes, the exhaustive classification of its phenomena, especially on genetic bases, the development of criteria of discrimination, the more complete evolution and formulation of its principles and the development of its working methods. the recent opening of new fields of research and the rapid progress of several new and important departments of the science give peculiar emphasis to this need. the rising generation of geologists, the hope of the science, should be schooled in these latest and most critical aspects of the science. a department of the =journal=, entitled "studies for students," has been opened for the special cultivation of this field and for its adaptation to advanced students and progressive teachers of geology. mere elementary presentations of processes and principles are not desired, but searching and critical expositions are solicited suited to the needs of young geologists who seek the highest professional equipment, and to progressive teachers who desire the fullest practicable command of the newest developments of the subject. these contributions may not be without their value to those who have already borne a considerable part of the heat and burden of life's professional day. it is our desire to open the pages of the =journal= as broadly as a due regard for merit will permit, and to free it as much as possible from local and institutional aspects. it will have the very important advantage of being published under the auspices and guarantee of the university of chicago, and will be free from the usual financial embarrassments attending the publication of a scientific magazine. this necessarily imposes upon the local editors the immediate responsibility for its editorship. beyond this, it is hoped that its institutional relationship will disappear entirely in an earnest effort to promote the widest interests of the science. as an earnest of this wider effort several eminent geologists, representing some of the leading universities of this country, and some of the great geological organizations of europe, have kindly consented to act as associate editors. t. c. c. [illustration] upon invitation of the world's congress auxiliary of the world's columbian exposition committees were appointed by the several sections of the american association for the advancement of science at its rochester meeting to coöperate with it in completing the organization of scientific congresses to be held at chicago in connection with the forthcoming world's fair. the committee appointed by the geological and geographical section consisted of thomas c. chamberlin, john c. branner, grove k. gilbert, w. j. mcgee, rollin d. salisbury, eugene a. smith, charles d. walcott, j. f. whiteaves, geo. h. williams, h. s. williams and n. h. winchell. it has been arranged that this committee should undertake the work of preparing the scientific program for the geological congress. the committee have prepared a provisional schedule of topics, which they have submitted to the advisory council for revision. it has seemed to the committee that all contributions should be such as to have an international interest. preferably, they should be subjects that can only be treated most advantageously in such a congress, especially those that involve the bringing together of data from different lands for comparison. the committee suggest the organization of the subjects under the following general classes: =first.= such as shall show the present state of geological progress. it is believed that this can best be done by an exhibition of geological maps which shall show the latest and best results of official and other surveys. as such maps will be prepared, it is hoped, for the world's fair, duplicates can be made at a slight expense for the use of the congress. it is hoped that each country that has made any notable progress in mapping its geological formations will furnish for the congress at least a general geological map, if not also special or analytical maps. =second.= such subjects as bear upon continental growth and intercontinental relations. it is proposed to make this a leading line of discussion during the congress, in the belief that there is no subject more appropriate, and that there is none which better represents the present efforts of geologists or commands a more general interest. it is hoped that analytical maps will be prepared by the geologists of the several countries representing the stages of growth of these regions in each of the great eras from the archean to the pleistocene, and that such analytical maps may constitute a leading feature of the several presentations. among the subjects upon which contributions are specially invited are the following: the correlation of continental and intercontinental orographic movements and geographic accretions by sedimentation; the coördination of periods of vulcanism in the different countries; the coördination of climatic states and changes; the correlation of faunal and floral variations and migrations. it is hoped that one session may be devoted to such coördination papers bearing upon each of the great subdivisions: viz., archean, paleozoic, mesozoic, cenozoic, and pleistocene. =third.= papers on paleontological and archeological geology of international scope. =fourth.= contributions to physical, structural and petrological geology having international or general bearings. =fifth.= contributions to economic geology having general bearings. =sixth.= miscellaneous papers of especial and general interest. the foregoing groups are intended to embrace and coördinate the list of special themes announced in the circular issued by the local committee some months since, except such as may be best suited to popular presentation, for which special provision is to be made. it will be determined later, when the number and nature of the papers are ascertained, whether all will be arranged so as to form a continuous program, or whether sub-sections will be formed and two or more sessions held simultaneously. it is the desire of the world's congress auxiliary that a few addresses of a popular nature shall be given, with a view to stimulating an interest in the development of the science on the part of the public. t. c. c. [illustration] extra copies of the articles appearing under the head of studies for students will be printed and kept on sale for the use of teachers and advanced classes. the prices will be fixed as low as practicable, and a standing list published in the advertising columns of the =journal=. =_reviews._= _on the glacial succession in europe._ by prof. =james geikie=. transactions of the royal society of edinburgh, vol. xxxvii., part i. (no. ), , pp. - (with a map). in this timely essay prof. geikie reaches the following conclusions: . the record of the first glacial epoch is found in the weyborn crag of britain, and the ground moraine beneath the "lower diluvium" of the continent. during this epoch, the direction of the ice movement in southern sweden was from the south-east to the northwest. this first glacial epoch of which direct evidence is adduced was followed by an interglacial interval, during which the forest-bed of cromer, the breccia of hötting, the lignites of leffe and pianico, and certain beds in central france were deposited. during this interglacial epoch, the climate is believed to have been very mild. . there followed a second epoch of glaciation, when the ice sheet of britain became confluent with that of the continent. this was the epoch during which the ice sheet reached its southernmost extension. its depositions are found in the lower boulder clays of britain, the lower diluvium of scandinavia and north germany (in part), the lower glacial deposits of south germany and central russia, the ground moraines and high level gravel terraces of alpine lands, and the terminal moraines of the outer zone. during this second glacial epoch, alpine glaciers are believed to have attained their greatest development. this epoch of extreme glaciation was followed by an interglacial interval, during which britain is believed to have been joined to the continent. during this interval, the climate became temperate. in russia (near moscow) there seems to be evidence that it was milder and more humid than that of the same region at the present day. toward the close of the mild epoch, submergence seems to have been accompanied by an increasing degree of cold, which finally ended in another glacial epoch. . the subsidence which marked the close of the second interglacial interval, marked likewise the inauguration of the third glacial epoch. its work is represented in britain by the upper boulder clay, in scandinavia and germany by the lower diluvium (in part), in central russia by the upper glacial series, in alpine lands by ground moraines and gravel terraces. the ice sheets of scandinavia and britain were again confluent, but did not extend quite so far south as during the second glacial epoch. this third glacial epoch is believed to have been followed by another interglacial interval, during which fresh water alluvia, lignite and peat accumulations were made. these are represented by the interglacial beds of north germany, and by some of the so-called post-glacial alluvia of britain. there were also marine deposits on the coasts of britain and on the borders of the baltic. during this interglacial interval, britain is believed to have been continental. the climate was temperate, but in the course of time became more severe. this increasing severity seems to have been accompanied by submergence, which amounted to something like ft. below the present sea-level on the coasts of scotland. the baltic provinces of germany were also invaded by the waters of the north sea. . there followed a fourth period of glaciation, during which the major part of the scottish highland was covered by an ice sheet. local ice sheets existed in the southern uplands of scotland and in mountain districts in other parts of britain, and the great valley glaciers sometimes coalesced on the low lands. icebergs floated out at the mouths of some of the highland sea-lochs. in some places, terminal moraines were deposited upon marine beds which were then in process of formation. these beds are now ft. above the sea level. at this time scandinavia was covered by a great ice sheet, which yielded icebergs to the sea along the whole west coast of norway. the ground moraines and terminal moraines of the mountain regions of britain represent the deposits of this ice epoch. the upper diluvium of scandinavia, finland, and north germany represent the work of the contemporaneous, but not confluent, ice sheet of the continent. in the alps, terminal moraines in the large longitudinal valleys were made at the same time. this fourth glacial epoch was followed by a fourth interglacial interval, during which fresh water alluvial deposits were made, and also the "lower buried forest and peat" of britain and northwestern europe. at this time, scotland seems to have stood to feet lower than now, and carse clays and raised beaches represent the work of the sea. during this interglacial interval, britain is believed to have become again continental, while the climate became so far ameliorated as to allow the growth of great forests. subsequently the insulation of britain was effected, and this was followed by a climate which was probably colder than the present. . the severity of the climate which marked the close of the fourth interglacial interval was such as to bring about local glaciation in some of the mountain valleys of britain. here and there the glaciers projected their moraines so far down the mountains that they rest on what is now the to feet beach. in the alps, this fifth epoch of glaciation is represented by the so-called post-glacial moraines in the upper valleys. this is believed to have been the last appearance of glaciers in britain. the dissolution of these glaciers was again followed by an emergence of the island, and by more genial climatic conditions. in support of his conclusions, prof. geikie cites some striking facts which are not so widely known as they should be. for example, swedish geologists have found evidences that there was an ice sheet antedating that which deposited the "lower diluvium," and that during this earlier glaciation the direction of ice movement in southern sweden was from the south-east to the north-west. the ground moraine deposited by this ice sheet is overlain by the "lower diluvium" which was produced by an ice movement from the north north-east to the south south-west, or nearly at right angles to the first. again, near moscow, there exist interglacial beds whose plant remains indicate a climate milder and more humid than that of the present time. these interglacial beds, it will be observed, occur in the region of the "lower diluvium" quite beyond the margin of the ice which produced the "upper diluvium" of germany and scandinavia. during this interglacial interval, prof. geikie maintains that no part of russia could have been covered with ice. if, then, within the limits of the area covered by the "lower diluvium," and not by the "upper," distinct beds of glacial drift are separated by such beds as those cited, there can be no question but that such separation marks two distinct glacial epochs. if there was an earlier glaciation when the movement of the ice in sweden was at right angles to that during which the lower part of the "lower diluvium" was produced, this also would seem to be good evidence of three ice epochs prior to the "upper diluvium." the epoch of the "upper diluvium" would then constitute the fourth glacial epoch, and this is the interpretation of prof. geikie. outside the area of the european continental ice sheet, facts are adduced in striking confirmation of the multiple ice epoch theory. these facts are found in switzerland, where evidences of multiple glaciation have been recognized, and in the pyrenees where evidences of three separate ice epochs have been found. in france, evidences of an interglacial interval have been found in the region of the puy de dôme of such duration as to allow the excavation of valleys to a depth of feet. the length of time which would be required for such stupendous erosion must certainly be regarded as sufficient to allow the preceding and succeeding glaciations to be considered as belonging to two distinct epochs. another point of great significance and interest which prof. geikie's essay brings out, is the correlation in britain between epochs of glaciation and epochs of subsidence on the one hand, and between interglacial intervals and epochs of elevation on the other. if prof. geikie's interpretation be well founded, and so far as we are able to judge from the facts presented this is the case, his conclusions would seem to be fatal to the hypothesis that glacial climate was produced by northern elevation. the map which prof. geikie gives, showing the limit of ice advance during the fourth glacial epoch, seems to us open to criticism. on the ground of personal observation, the writer believes that the ice sheet of the glacial epoch here represented did not extend notably, if at all, beyond the baltic ridge.[ ] [ ] see _american journal of science_, may, . in a recent letter, prof. geikie indicates that he is convinced, from subsequent personal observation, that his map is erroneous so far as the limit of the ice of this epoch is concerned. the mapping given was based on the opinion of others. prof. geikie is an advocate of dr. croll's astronomical theory of glacial climate, and thinks that even five is not the full number of glacial epochs belonging to the pleistocene period. he believes there may have been a series of glacial epochs increasing in severity to a maximum represented by what is now designated as the second glacial epoch. this maximum was followed by a series of epochs of diminishing severity, represented by what he designates the third, fourth and fifth epochs. the essay is a timely contribution to glacial geology. =rollin d. salisbury.= =_analytical abstracts of current literature._=[ ] [ ] abstracts in this number are prepared by henry b. kummel, chas. e. peet, j. a. bownocker. _the sub-glacial origin of certain eskers._ by =william morris davis=, harvard university. (proceedings of the boston society of natural history, vol. xxv., may , ). a critical discussion of the conditions under which it is conceived certain eskers and sand plateaus (plains) were formed. the auburndale district, ten miles east of boston, presents three classes of modified drift deposits;--sand plateaus, eskers, and kames. these deposits are well exposed. the sand plateaus have the characteristics of delta deposits of glacial streams,--even surfaces, well-bedded sands and gravels, the beds sloping outward from the "head" at an angle of ° to °, and in close agreement with the slope of the plateau front, a lobate margin, deposits distinctly coarser at the head than near the front, and a series of nearly horizontal roughly cross-bedded gravels overlying the sloping beds. the eskers are essentially of the same material as that of the plateau, often so poorly stratified as to render differentiation of the beds difficult. the interstices between the pebbles are often unfilled, although there is abundance of fine material in adjoining layers. this "open work" is taken to indicate rapid deposition, and seems to preclude the supposition that the gravels have settled down from a superglacial position, or been traversed by currents of any volume. in several instances the eskers can be followed to direct union with sand plateaus. towards its lower end the esker frequently "gives out branches" and "the adjacent lowland surface becomes more or less encumbered with sand mounds or kames," indicating a decayed margin of the ice. prof. davis' conclusions are: " . the eskers and sand plateaus of auburndale and newtonville were formed by running water just inside and outside of the ice margin in the closing stage of the last glacial epoch. " . the ice-sheet was a stagnant, decaying mass at the time of their formation, as is shown by the ragged outline of its margin. " . eskers and sand plateaus are genetically connected; the term, feeding-esker, is fully warranted by the relation of the two in position, structure, and composition. " . the sand plateaus were made rapidly; this is proved by the absence of disordered beds at their heads, where space would have been opened by the backward melting of the ice had the forward growth of the plateau been slow. the eskers were also made rapidly, as is shown by their 'open-work gravels.' " . the diversion of the feeding streams to other outlets left the plateaus and the eskers without further energetic action as the ice melted away from them. " . the present form and structure of the eskers are more accordant with the supposition of a subglacial origin than of a superglacial origin; but it is not intended to imply that other eskers of more irregular form and different structure could not have been deposited in superglacial channels." h. b. k. * * * * * _studies in structural geology._ by =bailey willis=, u. s. geol. surv. (transactions of the american institute of mining engineers, june, ). the paper aims "to present some of the results of observation of the geologists of the appalachian division during the past three years on the subject of structural geology in the appalachian province." the structural features are all of one type but of different phases, comprised in four great districts. ) the district of close folding, ) a district whose chief structural characteristic is cleavage, ) a district of open folding, ) a district of faulting and folding. the answer to the questions, why did the strata bend in the district of open folding, and why did they break in the district of faulting, is that the thrust affected them according to their rigidity under their respective conditions of superincumbent load. "we know that load up to a certain point restrains fracture in material under thrust." in the district of open folding the devonian limestone is the most rigid of the strata and "the one which would most effectively transmit the compressing thrust and would control the resulting structure." in the district of open folding this limestone was prevented from breaking and faulting by a load of superincumbent strata exerting a pressure of , to , pounds per square inch, while in the faulted district a load of , to , pounds per square inch permitted the strata to break and fault. the answer to the question, why did the compression affect this zone, is given. "it becomes apparent on study of sections that where compression raised a great arch there previously existed a bend from a nearly horizontal to a descending position in the principal stratum transmitting the thrust. greater anticlines and synclines originated in upward and downward convexity of initial dips, due to unequal deposits of sediments which depress underlying strata in proportion to their weight. such folds may be called original." the pottsville, mahanoy, shamokin and wyoming coal basins of pennsylvania belong to this class. experiments have recently been carried on in the office of the united states geological survey reproducing the different forms of folding. the experiments differed from other experiments in that ) the materials used to simulate the stratified rocks varied in consistency from brittle to plastic, according to the depth at which deformation is supposed to take place; ) the compression was exerted under a movable load representing the weight of superincumbent strata; ) the strata rested on a yielding base to simulate the condition of support of any arc of the earth's crust. the following are the conclusions from the experiments: . "when a thrust tangentially affects a stratified mass, it is transmitted in the direction of the strata, and by each stratum according to its inflexibility. at any bend the force is resolved into components, one radial, the other tangential to the dip beyond the bend; the radial component, if directed downward, tends to depress the stratum and displace its support. . "a thrust so resolved can only raise an anticline or arch which is strong enough to sustain the load lifted by its development; such an arch may be called competent; and since strength is a function of the proportions of a structure, it follows that, for a given stratum, the size of a competent anticline will vary inversely as the load; or for a given load the size will vary as the thickness of the effective stratum. . "the superincumbent load borne by a competent anticline is transferred to the supports of the arch at the points of inflection of the limbs. . "when a competent arch is raised by thrust from one side, the load transferred may so depress the resulting syncline further from the force that an initial dip will be produced in otherwise undisturbed strata; this dip will rise to a bend from which a new anticline may be developed. this anticline is a result of the first, and may be called 'subsequent' in distinction to original folds. since subsequent folds are simply competent structures, their size will be determined by conditions of thickness and load, and for like conditions they should be equal; and they must, in consequence of conditions of development, be parallel to the original fold and to each other. an example of an original fold with its subsequent anticlines is the nittany arch and the group of parallel anticlines which lie southeast of it, extending northeast from the broad top basin." c. e. p. * * * * * _the catskill delta in the post-glacial hudson estuary._ by =william morris davis=. (from the proceedings of the boston society of natural history, vol. xxv., ). the post-tertiary trenches of the hudson and its tributaries are in the main filled with clay beds, which, covered by a thin deposit of sand, rise in terraces , , or even feet above tide-water. these clays are the result of a late glacial or post-glacial submergence of the valley, but their upper surface does not indicate the amount of their submergence, as they are bottom deposits. delta deposits made by the tributary streams, where they entered the hudson estuary, would indicate the amount of submergence. such deposits are found on the catskill a mile north of cairo, and eroded remnants are traceable for three or four miles down stream. the surface is characterized by great numbers of water-worn stones up to fifteen or eighteen inches in diameter. the lobate margin, where present, is poorly defined. these deposits range from feet (aneroid) above tide, up river, to feet further down. one-tenth of a cubic mile of material seems to have been washed into the catskill trench at the point of this delta between the time of the ice departure and the elevation of the land. subsequent terracing has removed half that amount. the course of the catskill at leeds, where it crosses a ledge of hard corniferous limestone is probably of post-glacial superimposed origin, but the preglacial valley cannot be definitely fixed. h. b. k. * * * * * _geological survey of alabama.--bulletin ._ by =c. willard hayes=. (report of the geology of northeastern alabama and adjacent portions of georgia and tennessee). this report covers an area of miles, two-thirds in alabama. topographically it falls into three divisions: ) the cumberland and other plateaus of the northwest; ) in the center, anticlinal valleys--browns and wills, with the synclinal mountains--sand and lookout; ) the monoclinal mountains, the "flatwoods" (coosa shales) and the chert hills (knox limestone) of the southeast. the drainage of the first is radial from the center of the plateau to the tennessee; that of the second, once consequent upon the folded structure, is now adjusted to the strike of the soft beds. the formations are cambrian, silurian, devonian and carboniferous. total thickness is from , to , feet in the east, but decreases westward. hard sandstones of the carboniferous form the cappings of the plateaus and synclinal mountains. in the anticlinal and monoclinal valleys the silurian and cambrian appear. the rocks pass from the nearly horizontal beds of the plateau region, by narrow unsymmetrical anticlines with steeper dip on the northwest side, and by broad shallow synclines, to the complicated folds of the southeast. the axes of these latter folds dip more or less abruptly northward and southward, causing the ridges to assume zigzag courses. synclines are often crossed by anticlines. thrust faults exist, some of great magnitude, and traceable for to miles. by the "rome thrust fault" the cambrian shales have been shoved four to five miles over upon the carboniferous shales. most of the overthrust strata have been worn away, but tongues of cambrian shale still remain to all appearances lying conformably upon the carboniferous strata. transverse thrust faults terminate gaylor's ridge, dirt seller mountain, and lookout mountain on the south. h. b. k. * * * * * _the correlation of moraines with raised beaches of lake erie._ by =frank leverett=, u. s. geol. surv. (wisconsin academy of science. vol. viii., ). references have been made in geological literature to the beaches of the eastern portion of the lake erie basin, but up to the time of mr. leverett's work none of the beaches had been completely traced. mr. gilbert had discovered that several of the raised beaches do not completely encircle lake erie, and supposed that their eastern termini represent the successive positions of the front of the continental glacier during its retreat northeastward across the lake erie basin. mr. leverett verifies this theory by demonstrating that certain moraines are the correlatives of the beaches. they are as follows: i. the van wert or upper beach and its correlative moraine, the blanchard ridge. ii. the leipsic or second beach and its correlative moraines. iii. the belmore, or third beach and its correlative moraine. i. the van wert beach extends eastward from the former southwestward outlet of lake erie near fort wayne, indiana, to findlay, ohio, where it joins the blanchard moraine. through indiana and ohio its altitude is quite uniformly feet above lake erie. while the van wert beach was forming, the ice front was the northeastern shore of the lake as far east as findlay, ohio, its position being marked by the blanchard moraine. east of findlay, where the van wert beach joins it, the moraine is of the normal type. but west of findlay, it presents peculiarities of topography and structure, resulting from the presence of lake water beneath the ice margin. the water was shallow and incapable of buoying up the ice-sheet, and producing icebergs. the motion of the water under the ice-sheet produced a variable structure. this is the only instance of a moraine demonstrably formed in lake water. ii. the leipsic, or second beach, was formed after the ice had retreated from its position marked by the blanchard moraine. its altitude is to feet above lake erie. it has its terminus near cleveland, where it connects with the western end of a moraine. iii. the belmore beach and its correlative moraine. between the leipsic beach and the present shore of lake erie are several beaches. one of these, the belmore beach, terminates near cleveland, while the others extend into southwestern new york, and probably connect with moraines, though this connection has not been traced. the general altitude of the belmore beach in ohio is to feet above lake erie. unlike the van wert and leipsic beaches, it does not directly connect with a moraine at its eastern end, but a gap of ten miles intervenes. terraces at cleveland, mr. leverett thinks, make a connection between the eastern end of the beach and the western end of the moraine at euclid, ohio. c. e. p. * * * * * _the climate of europe during the glacial epoch._ by =clement reid=. (natural science. vol. i, no. , ). _temperature of the sea._--the temperature of the english channel was similar to that where the isotherm of ° f. is now situated. the winter temperature can scarcely have been ° colder than at present. the mediterranean was perhaps ° colder than now. _temperature of the land (air)._--it does not appear that the climate of the lowlands of southern europe can have been ° lower than the present mean; ° or perhaps less appear to have been the refrigeration in the mediterranean region. the temperature at the southern margin of the ice-sheet was about ° colder than at present. the temperature increased rapidly towards the south. recent observations seem to show that throughout central europe there was a period of _dry_ cold, causing the country to resemble the arid regions of central asia. j. a. b. * * * * * _on the glacial period and the earth-movement hypothesis._ by =james geikie=, edinburgh, scotland. (read before the victoria institute, london). geologists generally admit that there have been at least two glacial epochs, separated by one well-marked interglacial period. the closing stage of the pleistocene period was one of cold conditions in northwestern europe, accompanied by land depressions. after this came a genial climate with a union of the british islands among themselves and also with the continent. this was followed by a cold, humid condition. upham maintains that the whole of north america north of the gulf of mexico stood at least three thousand feet higher at the beginning of the glacial epoch than at present. fiords were formed before glacial times and so can not be cited as evidence of high land during the glacial period. an elevation of land in the northern part of north america and europe could not produce glaciation in their southern parts. the deflection of the gulf stream by the sinking of the panama, professor geikie argues, could not produce the conditions which prevailed during the glacial epoch. the earth-movement hypothesis, he believes, accounts neither for the widespread phenomena of the ice-age, nor for the remarkable interglacial climates. some maintain that the warm interglacial period was produced by the rise of the panama land, the sinking of the lands to the north, and the turning of the gulf stream from the pacific into the atlantic. why then, asks professor geikie, do we not have such a climate now? j. a. b. =_acknowledgments._= the following papers have been donated to the library of the geological department of the university of chicago, mainly by their authors: =abbe, cleveland.= --on the production of rain. pp. . =ami, henry m.=, m.a., f.g.s. --on canadian extinct vertebrates. pp.--ottawa naturalist. --on the geology of quebec and environs. pp., pl.--bull. geol. soc. am., vol. , pp. - . --on the geology of quebec city, canada. pp.--canadian record sci., april, . --additional notes on ganiograptus thureani, mccoy, from the levis formation canada. pp.--canad. record sci., oct. . --reviews of reports and papers on canadian geology and paleontology. pp.--ottawa naturalist, oct.-dec. . --notes and descriptions of some new or hitherto unrecorded species of fossils from the cambro-silurian (ordovician) rocks of the province of quebec. pp.--canadian record of sci., april, . --review of catalogue of the fossil cephalopoda of the british museum, part , nautiloidea. by arthur h. foord, f.g.s. pp.--canadian record of sci., sept. . --on the sequence of strata forming the quebec group of logan and billings, with remarks on the fossil remains found therein. pp.--ottawa naturalist, june, . =andeæ, a. and a. osann.= --beiträge zur geologie des blattes heidelberg. pp., iii., pl.--aus den mittheilungen der grossh. badischen geologischen landesanstalt, ii bd. vii-xi. =baltzer, a.= --beiträge zur geognosie der schweizer-alpen über die frage, ob der granit-gneiss der nördlichen gränzregion der finsteraarhorn-centralmass eruptiv sei oder nicht, und über damit zusammenhängende probleme. pp., pl.--neues jahrbuch für mineralogie, . --beiträge zur geognosie der schweizer-alpen. ueber die marmorlager am nordrand des finsteraarhorn-massivs. pp., pl.--aus dem neuen jahrbuch für mineralogie, . --ueber den hautschild eines rochen aus der marinen molasse. pp., pl.--aus den mittheilungen der naturforschenden gesellschaft in bern. --ueber den natürlichen verkohlungsprozess. pp.--aus der vierteljahrs-schrift der zürcherischen naturforschenden gesellschaft. --randerscheinungen der centralgranitischen zone in aarmassiv. pp., pl.--aus dem neuen jahrbuch, . ii band. --beiträge zur geognosie der schweizer-alpen. ein beitrag zur kenntniss der glarnerschlinge. pp., pl.--aus dem neuen jahrbuch für mineralogie, geol. und pal. . --geologische skizze des wetterhorns in berner oberland. pp., pl., zeit. der deut. geolog. gesell, . --geognostich-chemische mittheilungen über die neuesten eruptionen auf vulcano und die producte derselben. pp., pl.--zeit. d. deut. geolog. gesell, . --ueber bergstürze in den alpen. pp., pl.--aus dem jahrbuch des s.a.c. (x. jahrgang) zürich, . =baker, frank c.= --notes on a collection of shells from the mauritius; with a consideration of the genus magilus of montfort. pp., pl.--proc. rochest. acad. sci., vol. , . --catalogue and synonomy of the recent species of the family of muricidæ, first paper. pp.--proc. rochest. acad. sci., vol. i, . --description of new species of muricidæ with remarks on the apices of certain forms. pp., pl.--proc. rochest. acad. sci., vol. i, . =barrois, charles.= --sur la présence de fossiles dans le terrain azoique. pp.--comptes rendus des séances de l'académie des sciences, aug. , . =beecher, c.e., ph.d.= --the development of some silurian brachiopods. pl., pp.--n. yr state mus., vol. i, no. i, oct. . --brachiospongidæ, a memoir on a group of silurian sponges. pp., pl. memoirs of the peabody mus., vol. ii, part i, . --insecta by alpheus hyatt and j. m. arms.--am. jour. sci., march, . --new types of carboniferous cockroaches from the carboniferous deposits of the united states; ( ) new carboniferous myriapoda from ill.; ( ) illustrations of the carboniferous arachnida of n. a., of the orders anthracomarti and pedipalpi; ( ) the insects of the triassic beds at fairplay, col., samuel h. scudder. pp.--am. jour. sci., jan., . --some abnormal and pathologic forms of fresh water shells from the vicinity of albany, n. y. pp., pl.-- th rep. n. y. state mus. of nat. hist. --the development of a paleozoic poriferous coral. symmetrical cell development in the favositidæ. pp., pl.--trans. conn. acad. sci., vol. , . --on leptænisca, a new genus of brachiopod from the l. helderberg group. n. a. species of strophalosia. pp., pl.--am. jour. sci., sept., . --ceratiocaridæ from the chemung and waverly groups at warren, penn. pp., pl.--rep. of prop., ppp, d geol. surv. penn., . --a spiral bivalve from the waverly group of penn. pp., pl.-- th an. rep. n. y. state mus., . --on the lingual dentition and systematic position of pyrgula. pp., pl. jour. n. y. mic. soc., jan., . --on the occurrence of u. silurian strata near penobscot bay, maine. pp., ill.--am. jour. sci., may, . --koninckina and related genera. pp., pl.--am. jour. sci., sept., . --development of the brachiopoda, part i, introduction. pp., pl.--am. jour. sci., apr., . --development of the brachiopoda. part ii, classification of the stages of growth and decline. pp., pl.--am. jour. sci., aug., . =beachler, chas. s.= --keokuk group of the miss. valley. pp.--am. geol., aug., . copies. --the rocks at st. paul, indiana and vicinity. pp.--am. geol., mch., . copies. =bigelow, frank h.= --notes on a new method for the discussion of magnetic observations. pp., pl.--bull. weather bureau, . =boehm, georg.= --ueber den fussmuskeleindruck bei pachyerisma. pp.--berichte der naturforschenden gesellschaft in freiburg i. b., . vi. . --megalodon, pachyerisma und diceras. pp. wood cuts.--aus den berichten der naturforschenden gesellschaft vi. . zu freiburg i. b., . --lithiotis problematica. pp., pl.--naturforschenden gesell. in freiburg, band ii. heft . --ueber das alter der kalke des col dei schiosi. pp.--der deut. geolog. gesell, . --ein beitrag zur kenntniss der kreide in den venetianer alpen. pp., pl. cuts.--aus den berichten der naturforschenden gesellschaft zu freiburg i. b. band vi. heft . --die bivalven der schichten des diceras muensteri (diceraskalk) von kelhein. pp.--zeit. deut. geol. gesell. . --ueber die fauna der schichten mit durga im departement der sarthe. pp., pl. wood cuts.--zeit. der deut. geol. gesell. bd. xl., . --die facies der grauen kalke von venetien im departement der sarthe. pp.--aus der zeit. der deut. geol. gesell, . --südalpine kreideablagerungen. pp.--aus der zeit. d. deut. geol. gesell, bd., , heft. --ueber eine anomalie im kelche von millericrinus mespiliformis. pp., ill. zeit. der deut. geol. gesell., bd. , heft . =bowerman, a.= --the chinook winds and other climatic conditions of the northwest. pp.--hist. and sci. soc'y of manitoba, apr. , . =blanford, w. t.=, ll.d., f.r.s. --on additional evidence of the occurrence of glacial conditions in the paleozoic era, and in the geological age of the beds containing plants of the mesozoic type in india and australia. =brigham, albert p.= --a chapter in glacial history with illustrative notes from central new york.--trans. oneida hist. society, - . --the geology of oneida county. pp.--trans. oneida hist. society, - . --rivers and the evolution of geographic forms. pp., ill.--am. geog. soc'y, mch., . =chamberlin, t. c.= --hillocks of angular gravel and disturbed stratification. pp., ill.--am. jour. sci., may, . =carter, prof.= o. c. s. --ores, minerals and geology of montgomery county, pennsylvania, with map.--hist. of mont. co. --artesian wells in the lowest trias at norristown. pp.--proc. am. phil. soc., may , . =carpenter, commander a.=, r. n. --soundings recently taken off barren island narcondam, pl.--records geol. sur. ind., vol. xx, part , . =clarke, f. w.= --the meteoric collection in the u. s. nat. mus. a catalogue of meteorites represented. nov. , . pp. ill., pl. --some nickel ores from oregon, ill. pp.--am. jour. sci., june, . --tschemak's theory of the chlorite group and its alternative. pp.--am. jour. sci., march, . --on nephrite and jadeite. pp. pl. proc. u. s. nat. mus. xi, . --studies in the mica group. pp.--am. jour. sci., aug., . --a new occurrence of gyrolite. pp.--am. jour. sci., aug., . --experiments upon the constitution of the natural silicates. pp.--am. jour. sci., oct., nov., dec., . --mica. pp.--min. resources of the u. s., - . --note on the constitution of ptilolite and mordenite.--am. jour. sci., aug., . --on some phosphides of iridium and platinum on cadmium iodide. some sp. gr. determinations. researches on the tartrates of antimony.--am. chem. jour. vol. v., no. . --the fractional analysis of silicates. pp.--jour. am. chem. soc., vol. xii, no. . --a theory of the mica group. pp.--am. jour. sci., nov. . =clarke f. w. (and j. s. diller.)= --topaz from stoneham, maine. pp.--am. jour. sci., may, . --turquois from new mexico. pp.--am. jour. sci., sept., . =clarke f. w. (and charles catlett.)= --a platiniferous nickel ore from canada. pp.--am. jour. sci., may, . =clarke f. w. (and e. a. schneider.)= --on the constitution of certain micas, vermiculites and chlorites. pp.--am. jour. sci., sept., . =cohen, e.= --ueber einige eigenthümliche melaphyr-mandelsteine aus süd-afrika. pp. map, pl.--aus dem neuen jahrb. min., . mandelsteine aus den maluti-bergen, süd-africa, p. ibid., , bd. i. --ueber laven von hawaii und einigen anderen inseln des grossen oceans nebst einigen bemerkungen ueber glasige gesteine im allgemeinen. pp.--aus dem neuen jahrb. min. geol. und pal. , bd. ii. --goldführende conglomerate in süd-afrika. pp.--mit. des naturw. vereins für neu-vorpommern und ruegen, . --ueber die trennung von thonerde, eisenoxyd und titansäure. pp.--aus neuem jahrb. für min. . --chemische untersuchung des meteoreisens von s. juliao de moreira, portugal, sowie einiger anderen hexaëdrischen eisen. pp.--aus dem neuen jahrbuch für mineralogie, , bd. i. --zusammenstellung petrographischer untersuchungsmethoden nebst angabe der literatur. pp.--aus den mit. aus dem naturw. verein für neu-vorpommern und ruegen in greifswald. --ueber die entstehung des seifengoldes. pp.--mit. des naturw. vereins für neu-vorpommern und ruegen, . --geonostisch-petrographische skizzen aus süd-afrika. pp. pl.--aus dem neuen jahrbuch, min. . --ueber einige vogesengesteine. pp.--aus dem neuen jahrb. min. geol. und pal., , bd. i. --andalusitführende granite. pp.--aus dem neuen jahrb. min. , bd. ii. --nekrolog von jonas gustaf oscar linnarsson. pp.--aus dem neuen jahrb. min. . bd. i. --versammlung des oberrhein, geologischen vereins zu duerkheim, bayr. rheinpfalz, am , und april, . ueber einen aventurinquartz aus ostindien. --berichtigung bezüglich des "olivin-diallag-gesteins" von schriesheim im odenwald. pp.--aus dem neuen jahrb. min. , bd. i. --ueber pleochroitische höfe in biotit. pp.--aus den neuen jahrb. min. , bd. i. --kersantit von laveline. pp.--aus den neuen jahrb. min. . --das labradoritführende gestein der küste von labrador. pp.--aus den neuen jahrb. min. , bd. i. --ueber eine verbesserte methode der isolirung von gesteinsgemengtheilen vermittelst flussäure. pp.--mit. des naturw. vereines für neu-vorpommern und ruegen, . --die gold production transvaal in jahre . --ueber eine pseudomorphose nach markasit aus der kreide von arcona auf ruegen. pp.--aus den sitzungsberichten des naturw. vereins für neu-vorpommern und ruegen, . --das obere weilerthal und das zunächst angrenzende gebirge. pp.--abhandlungen zur geologischen speciakarte von elsass--lothringen. --ueber den granat der süd-afrikanischen diamantfelder und ueber den chromgehalt der pyrope. pp.--aus der mit. des naturw. vereins für neu-vorpommern und ruegen, . --ueber speckstein, pseudophit und dichten muscovit aus süd-afrika. pp.--aus dem neuen jahrb. min. , bd. i. --titaneisen von den diamantfeldern in süd-afrika. pp.--aus dem neuen jahrb. min. . --ueber den meteoriten von zsadany, temesvar comitat, banat. pp.--aus den verhandlungen des naturhist-med. vereins zu heidelberg. ii bd., heft. =cohen e.= und =w. deecke=. --ueber geschiebe aus neu-vorpommern und ruegen. pp.--aus den mitt. des naturwiss. vereines für neu-vorpommern und ruegen, . --sind die stoerungen in der lagerung der kreide an de ostküste von jasmund (ruegen) durch faltungen zu erklären? pp. pl.--aus den mit. des naturwiss. vereins für neu-vorpommern und ruegen, . --ueber das krystalline grundgebirge der inseln bornholm. =cohen e.= und =e. weinschenk=. --meteoreisen-studien. pp.--annalen des k. k. naturhistorischen hofmuseums. bd. vi. heft , . =cross, whitman.= --the post-laramie beds of middle park, colo. pp.--proc. colo. sci. soc., oct. , . --post-laramie deposits of colorado. pp.--am. jour. sci., july, . (and l. g. eakins). --a new occurrence of ptilolite.--am. jour. sci., aug., . =crosskey, h. w.= --on a section of glacial drift recently explored in icknield street, birmingham. pp., pl.--proc. birm. phil. soc. vol. iii, p. . --notes on some of the glacial phenomena of the vosges mountain, with an account of the glacier of kertoff. pp.--jan. , . --recent researches into the post-tertiary geology of scotland. pp.--phil. soc., glasgow, dec. , . --on the tellino calcarea bed at chappel hall, near airdrie. --some additions to the fauna of the bridlington (post-tertiary) bed. pp.--proc. birmingham phil. soc. vol. ii, part ii, june , . --report of the committee of the b. a. a. s. appointed for the purpose of recording the position, height above sea-level, character, etc. of erratic blocks of eng. wales and ire.--brit. assoc. , , , , , , , , , . (and =david robertson=). --the post-tertiary fossiliferous beds of scotland. pp., pl.--trans. geol. soc. glasgow, vol. iv, part iii, page . pp., vol. v., part i, page . =davis w. m.= --the convex profile of bad land divides.--sci., oct. , . --the deflective effect of the earth's rotation. pp.--am. met. jour., april, . --the subglacial origin of certain eskers. pp.--proc. boston soc'y of nat. hist. vol. xxi, may, . --outline of a course in elementary descriptive and physical geography for grades iv. and v. in the cambridge grammar school, - . pp. --outline of elementary meteorology. a synopsis of course "geology i" at harvard college, - . =dawson, geo.= m.d., d. sc., f.g.s. --recent observations in the glaciation of br. columbia and adjacent regions. pp., pl.--geol. mag., aug., . =dawson, sir wm. j.= --the geological history of plants. pp.--botanical gazette, vol. xiii., no. . =deeche, w.= --der monte vulture in der basilicata (unteritalien) pp. map., pl.--aus dem neuen jahrb. min. geol. und pal. beilageband vii. =dewey, frederic p.= --a preliminary catalogue of the systematic collection in economic geology and metallurgy in the u. s. national museum. pp.--bull. u. s. nat. mus. no. . --plan to illustrate resources of the u. s. and their utilizations, at the world's industrial and cotton centennial exposition of - at new orleans. pp. proc. u. s. nat. mus. , appendix. --photographing the interior of a coal mine. pp., pl.--am. inst. min. eng., july, . --some canadian iron ores. pp.--trans. am. inst. min. eng., vol. xii. . --report of the department of metallurgy in the u. s. national museum. pp.--report to the nat. mus., - . --the department of metallurgy and economic geology in the u. s. nat. mus. pp.--am. inst. min. eng., sept., . --hampe's method of determination cu_{ }o in metallic copper. pp.--proc. u. s. nat. mus., . --porosity of specific gravity of coke. pp.--trans. am. inst. min. eng., june, . --the lewis and bartlett bag-process of collecting lead fumes at the lone elm works, joplin, mo. pp., ill.--am. inst. min. eng., feb., . --note on the nickel-ore of russell springs, logan co., kan.--am. inst. min. eng. --note on the falling cliff zinc mine. pp.--am. inst. min. eng., may, . --the heroult process of smelting aluminum alloys. pp.--am. inst. min. engin., feb., . --pig iron of unusual strength. pp.--am. inst. min. eng., oct., . =diller, j. s.= --geology of the taylorville region of california. pp., ill.--bull. geol. soc. am., vol. . pp. - . --peridotite of elliott county, kentucky. pp., ill.--bull. u. s. g. s., no. . --notes on the geology of northern cal. pp.--bull. u. s. g. s., no. . --fulgurite from mt. thielson, oregon. pp., ill.--am. jour. sci., oct., . --notes on the peridotite of elliot county, ky. pp.--am. jour. sci., aug., . --a late volcanic eruption in northern cal. and its peculiar lava. pp., xvii pl., cuts.--bull. u. s. g. s., , . =emmons, s. f.= --abstract of a report upon the geology and mining industry of leadville, colorado. pp., with maps.--ann. rep. u. s. g. s., - . --orographic movements in the rocky mountains. pp.--bull. geol. soc'y am., vol. i., pp - . --notes on the geology of butte, montana. pp.--trans. am. inst. min. eng., july, . --the genesis of certain ore deposits. pp.--trans. am. inst. min. eng., march, . --structural relations of ore deposits. pp.--am. inst. min. eng., feb., . --notes on the gold deposits of montgomery county, maryland. pp.--am. inst. min. eng., feb., . --on glaciers in the rocky mountains. pp.--proc. col. sci. soc'y, . --preliminary notes on aspen, col. pp.--proc. col. sci. soc'y, . --fluor-spar deposits of southern ill. pp, map.--am. inst. min. eng., baltimore meeting, feb., . --the mining work of the u. s. geol. survey. pp.--trans. am. inst. min. eng., washington meeting, feb., . --on the origin of fissure veins. pp.--proc. col. sci. soc'y, . =emmons, s. f.= (and =g. e. becker=). --geological sketches of the precious metal deposits of the western united states, with notes on lead smelting at leadville. pp.--tenth census u. s., vol. xiii "statistics and technology of the precious metals." =emerson, george h.= --observations on crystals and precipitations in blowpipe beads. pp., ill.--proc. am. acad. of arts and sci., march, . =fisher, rev. o.= --mr. mallet's theory of volcanic energy tested. pp.--phil. mag., oct., . --review of captain dutton's critical observations on theories of the earth's physical evolution. pp.--geol. mag., aug., . --on the possibility of changes in the latitude of places on the earth's surface. being an appeal to physicists. pp.--geol. mag., july, . --on theories to account for glacial submergence. pp.--phil. mag., oct., . --on dynamo metamorphism. pp.--geol. mag., july, . --on the warp, its age and probable connection with the last geological events. pp., ill.--quart. jour. geol. soc'y, nov., . --on implement-bearing loams in suffolk. pp.--proc. cambridge phil. soc'y, vol. iii, pt. vii. --on the brocklesham beds of the isle of wight basin. pp.--proc. geol. soc'y, may, . --on a mammaliferous deposit at barrington, near cambridge. pp., ill.--quart. journ. geol. soc'y, nov., . --on the denudation of soft strata. pp.--quart. journ. geol. soc'y, feb., . --on the occurrence of elephas meridonalis at dervlish, dorset. pp., ill.--quart. journ. geol. soc'y, nov., . --glacial action and raised sea-beds. pp., ill.--geol. mag., april, . --on the origin of the estuary of the fleet in dorsetshire. --on the brick-pit at lexden, near colchester (with notes on the coleoptera, by t. u. wollaston). pp., ill.--quart. journ. geol. soc'y of london, . --on faulting, jointing and cleavage. pp., ill.--geol. mag., may, . --remarks upon mr. mallet's strictures on the mathematical test applied to his theory of volcanic energy, by mr. o. fisher. pp.--phil. mag., feb., . --on the phosphatic nodules of the cretaceous rock of cambridgeshire. pp., pl.--quart. journ. geol. soc'y, feb., . --on faults. reply to professor blake's criticisms. pp.--geol. mag., sept., . --"uniformity" and "vulcanicity." pp.--geol. mag., march, . --the cause of slaty cleavage. pp.--geol. mag., april, . --on the thermal conditions and on the stratification of the antarctic ice. pp.--phil. mag., june, . --on cleavage and distortion. pp.--geol. mag., sep., . --on the ages of the "trail" and "warp." pp.--geol. mag., may, . --review of dutton's grand cañon, colorado. pp.--geol. mag., july, . --on the theory of the erosion of lake basins by glaciers. pp.--geol. mag., june, . --oblique and orthogonal sections of a folded plane. pp., ill.--geol. mag., jan., . --on the cromer cliffs. pp., ill.--geol. mag., april, . --on some natural pits on the heaths of dorsetshire. pp.--quart. journ. geol. soc'y, london, . --on cirques and toluses. pp.--geol. mag., jan., . --on a worked flint from the buck-earth of crayford, kent. pp.--geol. mag., june, . =frazer, dr. persifor.= --general notes on the new orleans industrial and cotton exhibition. pp.--journal franklin institution, june, . --the eozoic and lower paleozoic in south wales and their comparison with their appalachian analogues. pp.--am. inst. min. engin., feb., . --geological and mineral studies in nuevo leon and coahuilla, mexico. pp., =iii=, and maps.--am. inst. min. engin., feb., . --trap dykes in the archaean rocks of southeastern pennsylvania. pp.--am. phil. soc., oct. , . --classification of coals. pp.--trans. am. inst. min. engin., vol. vi, . --descriptive table of elements. pp.-- . --the late international geological congress at berlin. pp.--am. phil. soc'y, nov. , . --report of the american committee of the international congress of geologists. pp.--proc. a. a. a. s., vol. xxxv, august, . --general notes on the geology of york county, penn. pp.--colored maps. --on the physical and chemical characteristics of a trap occurring at williamson's point, penn. pp., colored plate. read before am. phil. soc'y, dec. , . --an hypothesis of the structure of the copper belt of the south mountain. pp., ill.--trans. am. inst. min. engin., june, . read at the roanoke, va., meeting. --a broader field for the u. s. geological survey. pp.--journ. franklin instit., sept., . --the peach bottom slates of the lower susquehanna, with sections of the right and left banks. pp., pl.--am. inst. min. eng., oct., . --reply to a paper entitled "notes on the geology of chester valley and vicinity." pp.--journ. franklin inst., april, . --mr. theodore d. rand's criticism of vol. c_{ } geology of chester county, penn. pp.--journ. franklin inst., oct., . --archaean characters of the rocks of the nucleal ranges of the antilles. p.--brit. assn., . --notes on fresh-water wells of the atlantic beach. pp.--journ. franklin inst., sept., . --the position of the american new red sandstone. pp.--trans. am. inst. min. engin., vol. v. --on the traps of the mesozoic sandstone in york and adams counties, penn. pp., pl.--am. phil. soc'y, april , . --the whopper lode, gunnison county, colo. pp.--am. inst. min. engin., aug., . --some copper deposits of carroll county, md. pp., pl.--am. inst. min. engin., aug., . --a convenient device to be applied to the hand compass. p.--am. phil. soc'y, dec. , . --the approaches to a theory of the causes of magnetic declination. pp.--am. phil. soc'y, apr. , . --on improvement in the construction of the hypsometric aneroid.--am. phil. soc'y, march , . --an exfoliation of rocks near gettysburg. pp.--am. phil. soc'y, dec. , . --note on the new geological map of europe. pp.--trans. am. inst. min. engin. --some supposed fossils from the susquehanna river, just south of the pennsylvania-maryland line. pp., pl.--proc. am. phil. soc'y xviii, sept. , . --missing ores of iron. pp., ill.--trans. am. inst. min. engin., vol. vi, . --the peach bottom slates of southeastern york and southern lancaster counties, penn. pp., . pl.--trans. am. inst. mining engin., . --a speculation on protoplasm. pp.--am nat., july, . --a mirror for illuminating opaque objects for the projecting microscope. pp.--am. phil. soc'y, feb. , . --the progress of chemical theory; its helps and hindrances. pp.--journ. franklin instit., apr., may and june, . --mineral formulæ. pp.--proc. acad. nat. sci., phila., july , . --notes from the literature on the geology of egypt, and examination of the syenitic granite of the obelisk which lieut. comd'r gorringe, u. s. n., brought to new york. pp., pl.--trans. am. inst. mining engin., . --report of committee on the international congress of geologists. pp.--proc. a. a. a. s., vol. xxxix, . --on certain trap rocks from brazil. pp.--proc. acad. sci., phila., . --an unjust attack. pp.--am. geol., jan., . --the philadelphia meeting of the international congress of geologists. pp., am. geol., june, . --report of the berlin international geological congress. pp.--am. jour. sci., xxx, december, . --mesozoic sandstone of the atlantic slope. pp.--am. nat., may, . --archæan-paleozoic contact near philadelphia, penn. pp., pl.--proc. a. a. a. s., vol. xxxiii, sept., . --report of the sub-committee of the berlin congress of geologists on the archæan. pp. --crystallization. pp., ill.--journal franklin inst., aug., . --origin of the lower silurian limonites of york and adams counties, pp.--am. phil. soc'y, march , . --the northern serpentine belt in chester county, pa. pp.--trans. am. inst. min. engin., . --the persistence of plant and animal life under changing conditions of environment. pp.--am. nat., june, . --international congress of geologists, . pp., pl. --international congress of geologists, reports of the sub-committee appointed by the american committee. pp., . --other short articles. =frisbie, dr. j. f.= --glacial moraines. pp. --mountain building and mountain sculpture. pp. --the franconia flume, the causes that led to its formation. pp. --planet building. pp., pl. -- " " pp., pl. =geikie, sir archibald=, ll.d., d.sc, f.r.s.e., p.g.s. --address to the geological section of the british association. pp. --address by sir archibald geikie, president of british association for the advancement of science. . pp. --progress of the geological survey in scotland. pp.--proc. royal soc'y, edinburgh, vol. ii, session - . --on the tertiary volcanic rocks of the british islands. pp.--proc. royal soc'y, edinburgh, - . --the history of volcanic action during the tertiary period in the british islands (abstract). pp.--proc. royal soc'y, edin., . --address delivered at the th anniversary meeting of the edinburgh geological society. also notes for a comparison of the volcanic geology of central scotland with that of auvergne and the eifel. pp.--trans. of the edinburgh geological society, - , vol. ii, part i. --on modern denudation. pp.--trans. geol. soc'y of glasgow, vol. iii, p. . --on denudation now in progress. pp.--geol. mag., vol. i, no. , june, . --earth sculpture and the huttonian school of geology. the inaugural address delivered at the th anniversary meeting of the edinburgh geological society, nov. , . --recent researches into the origin and age of the highlands of scotland and the west of ireland. pp. --royal institute of great britain, . --the cañons of the far west.--ibid., april , . pp. --rock-weathering, as illustrated in edinburgh churchyards. pp., pl.--proc. royal soc'y, edinburgh, vol. x., april , . --the ancient glaciers of the rocky mountains. pp.--am. nat. jan. . --the ice age in britain.--science lectures for the people. pp. --the old man of hoy. pp., pl.--report brit. assoc., . --on the old red sandstone of the south of scotland. pp., pl.--quarterly journal geol. soc'y, aug. . --on the geology of strath, skye, (with descriptions of some fossils from skye, by t. wright, m.d., f.r.s.e.) pp., pl. --the history of volcanic action in the area of the british isles. pp.--quarterly journal of the geological society of london, vol. xlviii, . --on the supposed pre-cambrian rocks of st. david's. pp., pl.--quarterly journal of the geological society, aug. . --on the tertiary volcanic rocks of the british islands. pp., pl. --the geological origin of the present scenery of scotland. pp. ill.--the journal of travel and natural history. --on the age of the altered limestone of strath, skye.-- pp. ill.--quart. journal geol. soc'y, . --address of the president of the geological society of london, feb. , . pp. --the origin of coral reefs. pp. ill.--proc. royal physical soc'y. vol. viii, p.; . --the "pitchstone" of eskdale, a retrospect and comparison of geological methods. ibid, vol v, . =genth, f. a.= --ueber nordamerikanische tellur-und wismuth-mineralien. pp.--journal für praktische chemie, . --ueber lansfordit, nesquehonit und pseudomorphosen von nesquehonit nach lansfordit. (f. a. genth und s. l. penfield). pp., pl.--zeit. für krystallographie, . --contributions to mineralogy. pp., pl. read before am. phil. soc'y, oct. , . --do. pp. read before am. phil. soc'y, march , . --investigation of iron ores and limestones from blair and huntingdon counties, pa. pp.--read before the am. phil. soc'y, feb. , . --contributions to mineralogy. pp.--am. jour. sci., sept. ; pp. jan., . --do. with crystallographic notes by s. l. penfield. pp.--am. jour. sci., sept., ; pp. may, : pp. march, . --on american tellurium and bismuth minerals. pp.--am. phil. soc'y, aug. , . --on herderite. pp. read before am. phil. soc'y, oct. , . --on lansfordite, nesquehonite, a new mineral and pseudomorphs of nesquehonite after lansfordite. pp., pl.--am. jour. sci., feb., . --the minerals of north carolina.--bulletin , u. s. g. s. pp. --the minerals and mineral localities of north carolina. pp.--geol. of north carolina, vol. ii, . --first annual report of dr. f. a. genth, chemist of the pennsylvania board of agriculture. pp., . --second preliminary report on the mineralogy of pennsylvania, with analyses of mineral spring waters. pp. --ueber einige tellur-und vanad-mineralien. pp.--zeit. für krystallographie, etc., . --on the equivalent of cerium by the late dr. charles wolf. pp.--am. jour. sci., may, . --contributions to mineralogy, no. ; (with crystallographic notes by s. l. penfield). pp.--am. jour. sci., nov., . --on penfieldite, a new species. pp.--am. jour. sci., sept., . --mineralogische mittheilungen, by f. a. genth (with crystallographic notes by s. l. penfield). pp. ill.--"zeit. für krystallog." xviii, , ( ). --examination of the north carolina uranium minerals. pp.--am. chem. jour. vol. i, nos. and . --on some american vanadium minerals. pp.--am. jour. sci., july, . --on an undescribed meteoric iron from east tennessee. pp., pl.--proc. acad. nat. sci. phila., dec. , . --lansfordit, ein neues mineral, pp. --on the vanadates and iodyrite, from lake valley, sierra co., new mexico. pp. read before am. phil. soc'y apr. , . --contributions to mineralogy.--am. jour. sci., sept. ; march, , may, . --meteorology. pp. --meteorology. pp.--am. jour. sci., nov., . --re-examination of the tetradymite from field's gold mine, georgia. --on pyrophyllite from schuylkill co., penn. read before am. phil. soc'y, july , . --mineralogische mittheilungen. pp., pl.--zeit. für krystallographie, . --jarosite from utah. p.--am. jour. sci., jan., . --on two minerals from delaware co., pa. pp.--proc. acad. sci. of phila., . --contributions from the laboratory of the university of pennsylvania. =gilbert, g. k.= --the colorado plateau region considered as a field for geological study. pp.--am. jour. sci., july and august, . --the strength of the earth's crust. pp.--bull. geol. soc. am. vol. i, . --the history of the niagara river. pp., pl.--sixth an. rept. of com. of state reservation at niagara, . --the work of the international congress of geologists. pp.--am. jour. sci., dec, . --the sufficiency of terrestrial rotation for the deflection of streams. pp.--nat. acad. sci., . =gordon, c. h.= --observations on the keokuk species of agaricocrinus. pp., pl.--am. geol., may, . --on the brecciated character of the st. louis limestone. pp., pl.--am. nat., april, . --proceedings of the iowa academy of sciences for , , . pp. --quaternary geology of keokuk, iowa, with notes on the underlying rock structure. pp., pl. =grant, uly. s.= --notes on the molluscan fauna of minnesota. pp.-- th an. rept. geol. and nat. hist. survey, minn. ( ). --account of a deserted gorge of the mississippi near minnehaha falls. pp., pl. --conchological notes. pp.-- th an. rept. geol. and nat. hist. survey, minn. --the stratigraphical position of the ogishke conglomerate of northeastern minnesota. pp.--am. geol. vol. x, july, . --report of geological observations made in northeastern minnesota during the summer of . pp.--geol. and nat. hist. survey of minn.; part iv. th an. rept. =hall, c. w.= --notes on a geological excursion into central wisconsin. pp., pl. =hallock, william.= --chemical action between solids. pp.--am. jour. sci., may, . --the flow of solids or the behavior of solids under high pressure. pp.--bull. u. s. g. s., no. . --ueber die lichtgeschwindigkeit in verschiedenen quartzflächen. pp.--annalen der physik und chemie, . bd. xii. --preliminary report of observations at the deep well at wheeling, w. va.--proc. a. a. a. s., , vol. xl. =harden, john hy.=, m. e. --rock salt deposit of huron and bruce counties, ontario, canada. pp.--proc. engineer's club. phila., vol. i, no. . --the construction of maps in relief. pp., ill., pl.--trans. am. inst. min. eng., . =harpe, phil. de la.= --description des nummulites appartenant à la zone supérieure des falaises de biarritz. pp., pl.--bulletin de la société de borda, . --une Échelle des nummulites ou tableau de la distribution stratigraphique des espèces de nummulites. pp.--"verhandlungen" de la soc. helv. des sc. nat., session de st. gall, . --note sur les nummulites des alpes occidentales. pp.--extrait des actes de la soc. helv. des sc. nat., . --note sur les nummulites des environs de nice et de menton. pp., pl.--bulletin de la société geologique de france, octobre, . --ossements appartenant à l'anthracotherium magnum recueillis dans les lignites des environs de lausanne. pp.--bulletin de la soc. vaud. des sc. nat., . --note sur la géologie des environs de louèche-les-bains. pp., pl.--bulletin de la soc. vaud. des sc. nat., . --Étude sur les nummulites du comté de nice suivie d'une Échelle des nummulites ou tableau de la distribution stratigraphique des espèces de ce genre. pp., pl.--bulletin de la soc. vaud. des sc. nat. --nummulites des alpes francaises. pp.--bulletin de la soc. vaud. sc. nat. xvi, . --description des nummulites des falaises de biarritz. pp., pl.--extrait du bulletin de la société de borda, . --description des nummulites appartenant à la zone inférieure des falaises de biarritz des environs de la villa bruce jusqu'à handia. pp.--bulletin de la société de borda, . --description des nummulites appartenant à la zone moyenne des falaises de biarritz. pp., ill.--bulletin de la société de borda, . =hayes, c. willard.= --the overthrust faults of the southern appalachians. pp., pl.--bulletin geol. soc. am., vol. ii, pp. - . --report on the geology of northeastern alabama and adjacent portions of georgia and tennessee. pp., pl., map.--bulletin no. , geol. surv. of alabama. --an expedition through the yukon district. pp., maps.--nat. geog. mag. =heyes, j. f.=, m.a. --aspects of imperial federation. pp. --scientific aspects of imperial unity.--european mail. --the recognition of geography. pp. (_further acknowledgments of pamphlets and of specimens will be made in the next issue._) * * * * * transcriber note illustrations were moved so as to not split paragraphs. minor errors were corrected. by the same author. the foraminifera an introduction to the study of the protozoa by frederick chapman, a.l.s., f.r.m.s. this book has been written with a view of meeting a demand which has arisen for a concise account of the foraminifera, suited to the requirements of the student of natural history and palaeontology. with plates and illustrations in the text. demy vo. cloth, s. d. [illustration: the keystone printing co., - lonsdale st., melb.] [illustration: =a fossil crinoid= (helicocrinus plumosus), about / nat. size, in silurian mudstone, brunswick, victoria. (_spec. in nat. mus., melbourne_). ] australasian fossils a students' manual of palaeontology by frederick chapman, palaeontologist to the national museum, melbourne. formerly assistant in the geological department of the royal college of science, london. assoc. linnean soc. [lond.], f.r.m.s., etc. author of "the foraminifera," "a monograph of the silurian bivalved mollusca of victoria," "new or little-known victorian fossils in the national museum," etc. with an introduction by professor e. w. skeats, d.sc., f.g.s. george robertson & company propy. ltd., melbourne, sydney, adelaide, brisbane and london. . to professor john wesley judd this work is dedicated as a slight tribute of esteem, and in grateful acknowledgement of kindly help and encouragement through many years. contents. page preface introduction by professor e. w. skeats, d.sc., f.g.s. part i.--general principles. chap. i.--nature and uses of fossils " ii.--classification of fossil animals and plants " iii.--the geological epochs and time-range of fossils " iv.--how fossils are found, and the rocks they form part ii.--systematic palaeontology. chap. v.--fossil plants " vi.--fossil foraminifera and radiolaria " vii.--fossil sponges, corals and graptolites " viii.--fossil starfishes, sea-lilies and sea-urchins " ix.--fossil worms, sea-mats and lamp-shells " x.--fossil shell-fish " xi.--fossil trilobites, crustacea and insects " xii.--fossil fishes, amphibians, reptiles, birds and mammals appendix.--notes on collecting and preserving fossils index list of illustrations. fig. page . fossil shells in clay . tracks, probably of crustaceans . structure of silicified wood in tangential section: _araucarioxylon daintreei_, chapm. . portrait of william smith . raised beach: brighton, england . raised beach: torquay, victoria . marine fossils in volcanic tuff: summit of snowdon . kitchen middens: torquay, victoria . submerged forest on the cheshire coast . _pecten murrayanus_, tate. a fossil shell allied to a living species . cliff section: torquay, victoria . diagram of superposition of strata . diagram of the range-in-time of australasian fossils . _diprotodon_ skeletons in situ: lake callabonna, s. australia . bird remains on sand dunes: king island, bass strait . impression of bird's feather in ironstone: western victoria . a fossil turtle: _notochelone costata_, owen sp. . a ganoid fish: _pristisomus crassus_, a. s. woodward . a fossil insect in amber (_tipula sp._) . a fossil crustacean: _thalassina emerii_, bell . an ammonite: _desmoceras flindersi_, mccoy sp. . belemnites: _belemnites diptycha_, mccoy . a group of lamp-shells: _magellania flavescens_, lam. sp. . zoarium of a living polyzoan: _retepora_ sp. . a fossil polyzoan: _macropora clarkei_, t. woods sp. . fossil worm-tubes: (?) _serpula_ . a living sea-urchin: _strongylocentrotus erythrogrammus_, val. . a fossil sea-urchin: _linthia antiaustrails_, tate . a fossil brittle-star: _ophioderma egertoni_, brod. sp. . a fossil crinoid: _taxocrinus simplex_, phillips sp. . graptolites on slate: _tetragraptus fruticosus_, j. hall sp. . a stromatoporoid: _actinostroma_ . corals in devonian marble: _favosites_ . siliceous skeleton of a living sponge: (?) _chonelasma_ . spicules of a fossil sponge: _ecionema newberyi_, mccoy sp. . nummulites: _n. gizehensis_, ehr. var. _champollioni_, de la harpe . cainozoic radiolaria . radiolaria in siliceous limestone . travertin limestone, with leaves of beech (_fagus_) . freshwater limestone with shells (_bulinus_) . hardened mudstone with brachiopods (_orthis_, etc.) . diatomaceous earth . _lepidocyclina_ limestone . coral in limestone: _favosites grandipora_, eth. fil. . crinoidal limestone . turritella limestone . ostracodal limestone . _halimeda_ limestone . tasmanite: a spore coal . kerosene shale . bone bed . bone breccia . cainozoic ironstone with leaves (_banksia_) . _girvanella conferta_, chapm., in silurian limestone . palaeozoic plants . restoration of _lepidodendron_ . stem of _lepidodendron (lepidophloios)_, showing leaf-scars . upper palaeozoic plants . map of gondwana-land . mesozoic plants . cainozoic plants . eucalyptus leaves from the deep leads . palaeozoic and mesozoic foraminifera . _lepidocyclina marginata_, mich. sp. sections of shell showing structure . cainozoic foraminifera . fossil radiolaria . palaeozoic sponges and archaeocyathinae . cainozoic sponges . silurian corals . upper palaeozoic corals . cainozoic corals . stromatoporoidea and cladophora . lower ordovician graptolites . lower ordovician graptolites . upper ordovician and silurian graptolites . fossil crinoids . fossil starfishes . _protaster brisingoides_, gregory, in silurian sandstone . _gregoriura spryi_, chapm., in silurian mudstone . cainozoic sea-urchins . cainozoic sea-urchins . fossil worms . palaeozoic polyzoa . cainozoic polyzoa . lower palaeozoic brachiopods . silurian and devonian brachiopods . carbopermian brachiopods . mesozoic brachiopods . cainozoic brachiopods . lower palaeozoic bivalves . palaeozoic bivalves . carbopermian bivalves . lower mesozoic bivalves . cretaceous bivalves . cainozoic bivalves . cainozoic bivalves . fossil scaphopods and chitons . lower palaeozoic gasteropoda . silurian gasteropoda . upper palaeozoic gasteropoda . mesozoic gasteropoda . cainozoic gasteropoda . cainozoic gasteropoda . late cainozoic and pleistocene gasteropoda . palaeozoic cephalopoda . mesozoic and cainozoic cephalopoda . diagram restoration of an australian trilobite (_dalmanites_) . cambrian trilobites . older silurian trilobites . newer silurian trilobites . carboniferous trilobites and a phyllopod . silurian ostracoda . upper palaeozoic and mesozoic ostracoda . cainozoic ostracoda . fossil cirripedes . cirripedes. _lepas anatifera_, linn.: living goose barnacle, and _l. pritchardi_, hall: cainozoic . _ceratiocaris papilio_, salter . ordovician phyllocarids . silurian phyllocarids . fossil crabs and insects . silurian eurypterids . _thyestes magnificus_, chapm. . _gyracanthides murrayi_, a. s. woodw. restoration . teeth and scales of palaeozoic and mesozoic fishes . _cleithrolepis granulatus_, egerton . tooth of _ceratodus avus_, a. s. w., and phalangeal of a carnivorous deinosaur . scale of _ceratodus ? avus_ . the queensland lung-fish: _neoceratodus forsteri_, krefft . _leptolepis gregarius_, a. s. w. . cretaceous and cainozoic fish-teeth . cainozoic fish remains . _bothriceps major_, a. s. w. . _ichthyosaurus australis_, mccoy . fossil reptiles . impression of bird's feather, magnified, cainozoic: victoria . _cnemiornis calcitrans_, owen . _dinornis maximus_, owen. great moa . _pachyornis elephantopus_, owen . skeleton of _sarcophilus ursinus_, harris sp. . skull of fossil specimen of _sarcophilus ursinus_ . _thylacinus major_, owen. hind part of mandible . _phascolomys pliocenus_, mccoy. mandible . cainozoic teeth and otolith . skeleton of _diprotodon australis_, owen . right hind foot of _diprotodon australis_ . restoration of _diprotodon australis_ . skull and mandible of _thylacoleo carnifex_, owen . _wynyardia bassiana_, spencer . tooth of _scaldicetus macgeei_, chapm. . impressions of footprints in dune sand-rock, warrnambool map of australia, showing chief fossiliferous localities. preface. the more important discoveries of fossils in the southern hemisphere have received, as a rule, very meagre notice in many of the text-books of geology and palaeontology published in england, germany and america, and used by australasian students. it is thought, therefore, that the time has arrived when an attempt should be made to collect the main facts bearing upon this subject, in order to present them from an _australasian_ standpoint. with this in view, references to fossils occurring in the northern hemisphere are subordinated, seeing that these may be easily obtained on reference to the accepted text-books in general use. the present work does not presume to furnish a complete record of australasian palaeontology, since that would mean the production of a much more extensive and costly volume. sufficient information is here given, however, to form a groundwork for the student of this section of natural science, and a guide to the collector of these "medals of creation." the systematic portion of this book has been arranged primarily from the biological side, since palaeontology is the "study of ancient life." taking each life-group, therefore, from the lowest to the highest types, all the divisions represented by fossils are dealt with in turn, beginning with their occurrence in the oldest rocks and ending with those in the newest strata. if a commendation of the study of fossils, apart from its scientific utility, were needed, it could be pointed out that palaeontology as a branch of geology is, _par excellence_, an open-air study: and since it requires as handmaids all the sister sciences, is a subject of far-reaching interest. microscopy and photography are of immense value in certain branches of fossil research, the former in the examination of the minute forms of mollusca, foraminifera and ostracoda, the latter in the exact portraiture of specimens too intricate to copy with the brush, or too evanescent to long retain, when out of their matrix, their clean fresh surfaces. with geology or palaeontology as an objective, a country walk may be a source of much enjoyment to its students, for "in their hand is nature like an open book"; and the specimens collected on a summer excursion may be closely and profitably studied in the spare time of the winter recess. the author sincerely trusts that students may share the same pleasure which he has derived from the study of these relics of past life; and that the present attempt to show their relationship both in geological time and biological organisation, may be the means of inducing many to make further advances in this fascinating subject. in the production of this work several friends and collaborators have materially assisted, their aid considerably increasing its value. it is therefore with grateful thanks that the author acknowledges the help and encouragement given by professor e. w. skeats, d.sc., who has not only been good enough to write the introductory passages, but who has carefully gone over the ms. and made many helpful suggestions. mr. w. s. dun, f.g.s., palaeontologist to the geological survey branch of the department of mines, sydney, has also rendered generous help in giving the benefit of his full acquaintance of the palaeontology of his own state. to the trustees of the national museum the author is under special obligations for permission to photograph many unique fossil specimens in the museum collection, comprising figs. , - , - , - , , , , , , - , , , , , , , , and . the author's thanks are also due to dr. e. c. stirling, m.d., m.a., f.r.s., for permission to use figs. , and , whilst similar privileges have been accorded by prof. a. g. seward, f.r.s., dr. f. a. bather, f.r.s., and mr. c. l. barrett. prof. t. w. edgeworth david, f.r.s., has kindly cleared up some doubtful points of stratigraphy and further increased the author's indebtedness by the loan of a unique slide of radiolaria figured on p. . mr. eastwood moore, to whom special thanks are due, has greatly added to the pictorial side of this work by his skillful help in preparing many of the illustrations for the press, as well as in the drawing of the several maps. the grouped sets of fossils have been especially drawn for this work by the author. they are either copied from authentic specimens or from previously published drawings; references to the authorities being given in the accompanying legends. dr. t. s. hall has kindly read the section on graptolites and mammalia. for many helpful suggestions and the careful reading of proofs, thanks are especially owing to mr. w. e. g. simons, mr. r. a. keble, and to my wife. introduction. geological department, the university, melbourne. william smith, the father of english geology, used to apologize for the study of palaeontology by claiming that "the search for a fossil is at least as rational a proceeding as the pursuit of a hare." those of us who are accustomed to take the field, armed with a hammer, in the search for "medals of creation" and from time to time have experienced the sporting enjoyment of bringing to light a rare or perfect specimen are quite prepared to support his claim. but the student of fossils needs the help of a text book to guide him to the literature on the subject, to help him with his identifications or to indicate that some of his finds are new and hitherto undescribed. european and american workers have long been provided with excellent books treating generally of fossils, but the illustrations have been quite naturally taken mainly from forms occurring in the northern hemisphere. our own fossil forms both plants and animals are numerous, interesting and in many cases peculiar, but the literature concerning them is so widely scattered in various scientific publications that a warm welcome should be given to this book of mr. chapman's, in which the australian evidence is brought together and summarised by one, whose training, long experience, and personal research qualify him to undertake the task. especially will teachers and students of geology and palaeontology value such an undertaking. workers in other countries who have only partial access to the australian literature on the subject should also find this a valuable book of reference. in the study of fossils we are concerned with the nature, evolution and distribution of the former inhabitants of the earth. the study of palaeontology may be justified as a means of scientific discipline, for the contributions the subject makes to the increase of natural knowledge and the unfolding of panoramas of ancient life. it also provides perhaps the most positive evidence in the story of evolution. so, too, the student of the present day distribution of animals and plants finds the key to many a problem in zoo-geography in the records of past migrations yielded by the study of fossils in different lands. the stratigraphical geologist is of course principally concerned with two important aspects of the study of fossils. the masterly generalisation of william smith that strata can be identified by their fossil contents established by close study of the rocks and fossils of the british oolites has been confirmed generally by subsequent work. the comparative study of the fossil contents of rocks in widely separated areas has proved to be the most valuable means by which the correlation of the rocks can be effected and their identity of age established. in some cases the recognition of a single fossil species in two areas separated, perhaps, by thousands of miles may suffice to demonstrate that the rocks are of the same age. for example, a graptolite such as _phyllograptus typus_ is found in many parts of the world, but has only a very restricted range in time. it has been found only in rocks of lower ordovician age. its occurrence in wales and in the rocks of bendigo practically suffices to establish the identity in age of the rocks in these widely separated areas. generally, however, much closer study and a more detailed examination of a large number of the fossils of a rock series are required before the age of the rocks can be surely established and a safe correlation made with distant localities. the stratigraphical generalisations to be made from the study of fossils however must be qualified by certain considerations. among these are the fact that our knowledge of the life forms of a given geological period is necessarily incomplete, that the differences in the fossil contents of rocks may depend not only on differences of age but also in the conditions under which the organisms lived and the rocks were accumulated, and that forms of life originating in one area do not spread themselves immediately over the earth but migrate at velocities depending on their mode of life and the presence or absence of barriers to their progress. our incomplete knowledge of the forms living in remote geological periods arises partly from the fact that some forms had no permanent skeleton and were therefore incapable of preservation, partly to the obliteration of the skeletons of organisms through subsequent earth movements in the rocks or through the solvent action of water. many land forms, too, probably disintegrated on the surface before deposits were formed over the area. apart from these causes which determine that a full knowledge of the fossils from ancient rocks in particular, will never be acquired, our knowledge is incomplete by reason either of difficulty of access to certain areas or incomplete search. as a result of later discoveries earlier conclusions based on incomplete evidence as to the age of a rock series, have not infrequently been modified. the study of the present distribution of animals and plants over the earth is a help in the attempt to decide how far the fossil differences in the sets of rocks are due to differences in the ages of the rocks or to differences in the conditions under which the organisms lived. the present, in this, as in many other geological problems, is the key to the past. we know, for instance, that differences of climate largely control the geographical distribution of land animals and especially of land plants, and for that reason among others, fossil plants are generally less trustworthy guides to geological age than fossil animals. in the distribution of marine animals at the present day we find that organisms of simple structure are generally more wide-spread and less susceptible to changes in their environment than are the more complex organisms with specialised structures. hence we find, for instance, a fossil species of the foraminifera may persist unchanged through several geological periods, while a species of fossil fish has in general not only a short range in time but often a restricted geographical extent. if we consider the marine organisms found at the present day we find a number of free-swimming forms very widely distributed, while a large number are restricted either by reason of climate or of depth. certain organisms are only to be found between high and low tide levels, others between low tide level and a depth of thirty fathoms, while many quite different forms live in deeper waters. if we confine our attention to shallow-water marine forms we note that certain forms are at the present day restricted to waters of a certain temperature. we find, therefore, a contrast between arctic and tropical faunas, while other types characterize temperate latitudes. climatic and bathymetrical differences at the present day therefore lead to distinct differences in the distribution of certain organisms, while other forms, less sensitive to these factors, range widely and may be almost universally distributed. similar conditions obtained in past geological times, and therefore in attempting to correlate the rocks of one area with those of another those fossils which are most wide-spread are often found to be the most valuable. attention should also be paid to the conditions under which the deposits accumulated, since it is clear that rocks may be formed at the same time in different areas and yet contain many distinct fossils by reason of climatic or bathymetrical differences. among living marine organisms we find certain forms restricted to sandy or muddy sea-bottoms and others to clear water, and these changes in the conditions of deposition of sediment have played their part in past geological periods in determining differences in the fossil faunas of rocks which were laid down simultaneously. we not infrequently find mudstones passing laterally into limestones, and this lithological change is always accompanied by a more or less notable change in the fossil contents of the two rock types. such facts emphasize the close connection between stratigraphy and palaeontology, and indicate that the successful tracing out of the geological history of any area is only possible when the evidence of the stratigrapher is reinforced by that provided by the palaeontologist. the fact that species of animals and plants which have been developed in a particular area do not spread all over the world at once but migrate very slowly led huxley many years ago to put forward his hypothesis of "homotaxis." he agreed that when the order of succession of rocks and fossils has been made out in one area, this order and succession will be found to be generally similar in other areas. the deposits in two such contrasted areas are homotaxial, that is, show a similarity of order, but, he claimed, are not necessarily synchronous in their formation. in whatever parts of the world carboniferous, devonian and silurian fossils may be found, the rocks with carboniferous fossils will be found to overlie those with devonian, and these in their turn rest upon those containing silurian fossils. and yet huxley maintained that if, say, africa was the area in which faunas and floras originated, the migration of a silurian fauna and flora might take place so slowly that by the time it reached britain the succeeding devonian forms had developed in africa, and when it reached north america, devonian forms had reached britain and carboniferous forms had developed in africa. if this were so a devonian fauna and flora in britain may have been contemporaneous with silurian life in north america and with a carboniferous fauna and flora in africa. this could only be true if the time taken for the migration of faunas and floras was so great as to transcend the boundaries between great geological periods. this does not appear to be the case, and huxley's idea in its extreme form has been generally abandoned. at the same time certain anomalies in the range in time of individual genera have been noted, and may possibly be explained on such lines. for instance, among the group of the graptolites, in britain the genus _bryograptus_ occurs only in the upper cambrian and the genus _leptograptus_ only in the upper ordovician rocks. in victoria these two genera, together with typical lower ordovician forms, may be found near lancefield preserved on a single slab of shale. in the same way, in a single quarry in triassic rocks in new south wales, a number of fossil fish have been found and described, some of which have been compared to jurassic, others to permian, and others to carboniferous forms in the northern hemisphere. another point which the palaeontologist may occasionally find evidence for is the existence of "biological asylums," areas which by means of land or other barriers may be for a long period separated from the main stream of evolution. we know that the present fauna and flora of australia is largely of archaic aspect, as it includes a number of types which elsewhere have long ago become extinct or were never developed. this appears to be due to the long isolation of australia and, as professor gregory happily puts it--its "development in a biological backwater." we have some evidence that similar asylums have existed in past geological periods, with the result that in certain areas where uniform conditions prevailed for a long time or where isolation from competition prevented rapid evolution, some organisms which became extinct in other areas, persisted unchanged in the "asylum" into a younger geological period. the broad generalizations that rocks may be identified by their fossil contents and that the testimony of the rocks demonstrates the general order of evolution from simple to complex forms, have only been placed on a surer footing by long continued investigations. the modifications produced by conditions of deposit, of climate and of natural barriers to migration, while introducing complexities into the problems of palaeontology, are every year becoming better known; and when considered in connection with the variations in the characters of the rocks, provide valuable and interesting evidence towards the solution of the ultimate problems of geology and palaeontology, which include the tracing out of the evolution of the history of the earth from the most remote geological period to that point at which the geologist hands over his story to the archaeologist, the historian, and the geographer. ernest w. skeats. part i. general principles. chapter i. nature and uses of fossils. =scope of geology.--= the science of geology, of which palaeontology or the study of fossils, forms a part, is concerned with the nature and structure of the earth, the physical forces that have shaped it, and the organic agencies that have helped to build it. =nature of fossils.--= the remains of animals and plants that formerly existed in the different periods of the history of the earth are spoken of as fossils. they are found, more or less plentifully, in such common rocks as clays, shales, sandstones, and limestones, all of which are comprised in the great series of sedimentary rocks (fig. ). according to the surroundings of the organisms, whether they existed on land, in rivers, lakes, estuaries, or the sea, they are spoken of as belonging to terrestrial, fluviatile, lacustrine, estuarine, or marine deposits. [illustration: =fig. .--fossil shells embedded in sandy clay.= about / nat. size. of cainozoic or tertiary age (kalimnan series). grange burn, near hamilton, victoria. (_f.c. coll._) (g = glycimeris. l = limopsis. n = natica).] [illustration: =fig. .--tracks probably of crustaceans (phyllocarids).= about / nat. size. impression of a slab of upper ordovician shale. diggers' rest, victoria. (_f.c. coll._) ] the name fossil, from the latin 'fodere' to dig,--'fossilis,' dug out,--is applied to the remains of any animals or plants which have been buried either in sediments laid down in water, in materials gathered together by the wind on land as sand-dunes, in beds of volcanic ash, or in cave earths. but not only remains of organisms are thus called fossils, for the name is also applied to structures only indirectly connected with once living objects, such as rain-prints, ripple-marks, sun-cracks, and tracks or impressions of worms and insects (fig. ). =preservation of fossils.--= in ordinary terms, fossils are the durable parts of animals and plants which have resisted complete decay by being covered over with the deposits above-named. it is due, then, to the fact that they have been kept from the action of the air, with its destructive bacteria, that we are able to still find these relics of life in the past. =petrifaction of fossils.--= when organisms are covered by a tenacious mud, they sometimes undergo no further change. very often, however, moisture containing mineral matter such as carbonate of lime or silica, percolates through the stratum which contains the fossils, and then they not only have their pores filled with the mineral, but their actual substance may also undergo a molecular change, whereby the original composition of the shell or the hard part is entirely altered. this tends almost invariably to harden the fossils still further, which change of condition is called petrifaction, or the making into stone. [illustration: =fig. . thin slice of petrified or silicified wood in tangential section.= araucarioxylon daintreei, chapm. = dadoxylon australe, arber; Ã� . carbopermian: newcastle, new south wales. (_nat. mus. coll._) ] =structure preserved.--= petrifaction does not necessarily destroy the structure of a fossil. for example, a piece of wood, which originally consisted of carbon, hydrogen, and nitrogen, may be entirely replaced by flint or silica: and yet the original structure of the wood may be so perfectly preserved that when a thin slice of the petrifaction is examined under a high power of the microscope, the tissues with their component cells are seen and easily recognised (fig. ). =early observers.--= remains of animals buried in the rocks were known from the earliest times, and frequent references to these were made by the ancient greek and roman philosophers. xenophanes.-- xenophanes, who lived b.c. , wrote of shells, fishes and seals which had become dried in mud, and were found inland and on the tops of the highest mountains. the presence of these buried shells and bones was ascribed by the ancients to a plastic force latent in the earth itself, while in some cases they were regarded as freaks of nature. leonardo da vinci.-- in the sixteenth and seventeenth centuries italian observers came to the fore in clearly demonstrating the true nature of fossils. this was no doubt due in part to the fact that the italian coast affords a rich field of observation in this particular branch of science. the celebrated painter leonardo da vinci (early part of the sixteenth century), who carried out some engineering works in connection with canals in the north of italy, showed that the mud brought down by rivers had penetrated into the interior of shells at a time when they were still at the bottom of the sea near the coast. steno.-- in , steno, a danish physician residing in italy, wrote a work on organic petrifactions which are found enclosed in solid rocks, and showed by his dissection of a shark which had been recently captured and by a comparison of its teeth with those found fossil in the cliffs, that they were identical. the same author also pointed out the resemblance between the shells discovered in the italian strata and those living on the adjacent shores. it was not until the close of the eighteenth century, however, that the study of fossil remains received a decided impetus. it is curious to note that many of these later authors maintained the occurrence of a universal flood to account for the presence of fossil shells and bones on the dry land. [illustration: =fig. .--william smith ( - .)= "the father of english geology," at the age of . (_from brit. mus. cat._) ] =fossils an index to age.--= a large part of the credit of showing how fossils are restricted to certain strata, and help to fix the succession and age of the beds, is due to the english geologist and surveyor, william smith (fig. ). "the father of english geology," as he has been called, published two works[ ] in the early part of last century, in which he expressed his view of the value of fossils to the geologist and surveyor, and showed that there was a regular law of superposition of one bed upon another, and that strata could be identified at distant localities by their included fossils. upon this foundation the work of later geologists has been firmly established; and students of strata and of fossils work hand in hand. [footnote : "strata identified by organised fossils," - ; and "stratigraphical system of organised fossils," .] =stratigraphy.--= that branch of geology which discusses the nature and relations of the various sediments of the earth's crust, and the form in which they were laid down, is called stratigraphy. from it we learn that in bygone times many of those places that are now occupied by dry land have been, often more than once, covered by the sea; and thus tennyson's lines are forcibly brought to mind-- "there where the long street roars hath been the stillness of the central sea." =elevated sea-beds.--= a striking illustration in proof of this emergence of the land from the sea is the occurrence of marine shells similar to those now found living in the sea, in sea-cliffs sometimes many hundreds of feet above sea-level. when these upraised beds consist of shingle or sand with shore-loving shells, as limpets and mussels, they are spoken of as raised beaches. elevated beaches are often found maintaining the same level along coast-lines for many miles, like those recorded by darwin at chili and peru, or in the south of england (fig. ). they also occur intermittently along the victorian coast, especially around the indents, where they have survived the wear and tear of tides along the coast line (fig. ). they are also a common feature, as a capping, on many coral islands which have undergone elevation. [illustration: =fig. .--a raised beach at black rock, brighton, england.= (_original_). ] [illustration: =fig. .--raised beach (a) and native middens (b)= torquay, victoria. (original). ] [illustration: =fig. .--marine fossils (orthis flabellulum, sowerby.)= about nat. size. in volcanic tuff of ordovician age. from the summit of snowdon, north wales, at an elevation of feet above sea level. (_f.c. coll._) ] =sea-beds far from the present coast.--= marine beds of deeper water origin may be found not only close to the coast-line, but frequently on the tops of inland hills some miles from the sea-coast. their included sea-shells and other organic remains are often found covered by fine sediment forming extensive beds; and they may frequently occur in the position in which they lived and died (fig. ). although it is well known that sea-birds carry shell-fish for some distance inland, yet this would not account for more than a few isolated examples. =raised beaches as distinct from middens.--= again, it may be argued that the primitive inhabitants of countries bordering the coast were in the habit of piling up the empty shells of the edible molluscs used by them for food: but these "kitchen middens" are easily distinguished from fossil deposits like shelly beaches, by the absence of stratified layers; and, further, by the shells being confined to edible species, as the cockle (_cardium_), the blood-cockle (_arca_), the mussel (_mytilus_), and the oyster (_ostrea_) (fig. ). [illustration: =fig. .--remains of edible shell fish= (kitchen-midden--native, mirrn-yong) in sand dunes near spring creek, torquay, victoria. (_original_). ] [illustration: =fig. .--part of a submerged forest= seen at low water on the cheshire coast at leasowe, england. (_from seward's "fossil plants"_) ] =submerged forests.--= evidence of change in the coast-line is shown by the occurrence of submerged forest-land, known as "fossil forests," which consist of the stumps of trees still embedded in the black, loamy soil. such forests, when of comparatively recent age, are found near the existing coast-line, and may sometimes extend for a considerable distance out to sea (fig. ). from the foregoing we learn that:-- _ .--fossils afford data of the various changes that have taken place in past times in the relative positions of land and water._ =changes of climate in the past.--= at the present day we find special groups of animals (fauna), and plants (flora), restricted to tropical climates; and others, conversely, to the arctic regions. cycads and tree-ferns, for example, seem to flourish best in warm or sub-tropical countries: yet in past times they were abundant in northern europe in what are now temperate and arctic regions, as in yorkshire, spitzbergen, and northern siberia, where indeed at one time they formed the principal flora. the rein-deer and musk-sheep, now to be found only in the arctic regions, once lived in the south of england, france and germany. the dwarf willow (_salix polaris_) and an arctic moss (_hypnum turgescens_), now restricted to the same cold region, occur fossil in the south of england. in southern australia and in new zealand, the marine shells which lived during the earlier and middle tertiary times belong to genera and species which are indicative of a warmer climate than that now prevailing; this ancient fauna being like that met with in dredging around the northern coasts of australia (fig. .) [illustration: =fig. .--a fossil shell (pecten murrayanus, tate).= of oligocene to lower pliocene age in southern australia; closely allied to, if not identical with, a species living off the coast of queensland. about nat. size. (_f.c. coll._) ] from the above evidence we may say that:-- _ .--fossils teach us that in former times the climate of certain parts of the earth's surface was different from that now existing._ =fossils as guides to age of strata.--= in passing from fossil deposits of fairly recent origin to those of older date, we find the proportion of living species gradually diminish, being replaced by forms now extinct. after this the genera themselves are replaced by more ancient types, and if we penetrate still deeper into the series of geological strata, even families and orders of animals and plants give place to others entirely unknown at the present day. from this we conclude that:-- _ .--fossil types, or guide fossils, are of great value in indicating the relative age of geological formations._ =gradual evolution of life-forms from lower to higher types.--= as a general rule the various types of animals and plants become simpler in organisation as we descend the geological scale. for example, in the oldest rocks the animals are confined to the groups of foraminifera, sponges, corals, graptolites, shell-fish and trilobites, all back-boneless animals: whilst it was not until the devonian period that the primitive fishes appeared as a well-defined group; and in the next formation, the carboniferous series, the first traces of the batrachians (frog-like animals) and reptiles are found. birds do not appear, so far as their remains are known, until near the close of the jurassic; whilst mammals are sparsely represented by monotremes and marsupials in the triassic and jurassic, becoming more abundant in cainozoic times, and by the eutheria (higher mammals) from the commencement of the eocene period. it is clear from the above and other facts in the geological distribution of animal types that:-- _ .--the geological record supports in the main the doctrine of evolution from simpler to more complex types; and fossils throw much light upon the ancestry of animals and plants now found living._ chapter ii. the classification of fossil animals and plants. an elementary knowledge of the principles underlying the classification of animals and plants is essential to the beginner in the study of fossils. =the naming of animals.--= in order to make a clearly understood reference to an animal, or the remains of one, it is as necessary to give it a name as it is in the case of a person or a place. before the time of linnaeus ( - ), it was the custom to refer, for example, to a shell, in latin[ ] as "the little spiral shell, with cross markings and tubercles, like a ram's horn;" or to a worm as "the rounded worm with an elevated back." improvements in this cumbersome method of naming were made by several of the earlier authors by shortening the description; but no strict rule was established until the tenth edition of linnaeus' "systema naturae" ( ), when that author instituted his binomial nomenclature by giving each form enumerated both a generic and specific name. in plain words, this method takes certain life-forms closely related, but differing in minute particulars, and places them together in a genus or kindred group. thus the true dogs belong to the genus _canis_, but since this group also includes wolves, jackals, and foxes, the various canine animals are respectively designated by a specific name; thus the dog (_canis familiaris_), the dingo (_c. dingo_), the wolf (_c. lupus_), the jackal (_c. aureus_), and the fox (_c. vulpes_). the generic name is placed first. allied genera are grouped in families, (for example, canidae), these into orders (ex. carnivora), the orders into classes (ex. mammalia), and the classes into phyla or subkingdoms (ex. vertebrata). [footnote : the latin description was used more commonly than it is at present, as a universal scientific language.] plants are classified in much the same way, with the exception that families and orders are, by some authors, regarded as of equal value, or even reversed in value; and instead of the term phylum the name series is used. classification of the animal kingdom. name of phylum. | forms found fossil ----------------------+------------------------------------------------- i.--protozoa | foraminifera, radiolaria. | ii.--coelenterata | sponges, corals, stromatoporoids, graptolites. | iii.--echinodermata | crinoids, starfishes, brittle-stars, sea-urchins. | iv.--vermes | worms (tube-making and burrowing kinds). | v.--molluscoidea | polyzoa or sea-mats, brachiopods or lamp-shells. | vi.--mollusca | shell-fish: as bivalves, tusk-shells, | chitons or mail-shells, gasteropods or | snails, pteropods or sea-butterflies; | cuttle-fishes. | vii.--arthropoda | joint-footed animals: as trilobites, cyprids, | crabs and lobsters, centipedes, spiders | and insects. | viii.--vertebrata | fishes, amphibians, reptiles, birds and mammals. classification of animal kingdom. the first seven groups of the above classification are back-boneless animals or invertebrata; the eighth division alone comprising the animals with a vertebra or backbone. =characters of the several phyla.--= in the first group are placed those animals which, when living, consist of only one cell, or a series of similar cells, but where the cells were never combined to form tissues having special functions, as in the higher groups. protozoa.-- the _amoeba_ of freshwater ponds is an example of such, but owing to its skin or cortex being soft, and its consequent inability to be preserved, it does not concern us here. there are, however, certain marine animals of this simple type of the protozoa which secrete carbonate of lime to form a chambered shell (foraminifera); or silica to form a netted and concentrically coated shell held together with radial rods (radiolaria); and both of these types are found abundantly as fossils. they are mainly microscopic, except in the case of the nummulites and a few other kinds of foraminifera, which are occasionally as large as a crown piece. coelenterata.-- the second group, the coelenterata, shows a decided advance in organisation, for the body is multicellular, and provided with a body-cavity which serves for circulation and digestion. the important divisions of this group, in which the organisms have hard parts capable of being fossilised, are the limy and flinty sponges, the corals, and allied groups, as well as the delicate graptolites which often cover the surface of the older slates with their serrated, linear forms, resembling pieces of fret-saws. echinodermata.-- the third group, echinodermata, comprises the sea-lilies (crinoids), starfishes and sea-urchins, besides a few other less important types; and all these mentioned are found living at the present day. their bodies are arranged in a radial manner, the skin being strengthened by spicules and hardened by limy deposits ultimately forming plates. they have a digestive canal and a circulatory system, and are thus one remove higher than the preceding group. vermes.-- the fourth group, vermes (worms), are animals with a bilateral or two-sided body, which is sometimes divided into segments, but without jointed appendages. those which concern the student of fossils are the tube-making worms, the errant or wandering worms which form casts like the lob-worm, and the burrowing kinds whose crypts or dwellings become filled with solid material derived from the surrounding mud. molluscoidea.-- group five, the molluscoidea, contains two types; the flustras or sea-mats (polyzoa) and the lamp-shells (brachiopoda). they are at first sight totally unlike; for the first-named are colonies of compound animals, and the second are simple, and enclosed between two valves. they show in common, however, a bilateral symmetry. the mouth is furnished with fine tentacles, or with spirally rolled hair-like or ciliated processes. mollusca.-- the sixth group, the mollusca, includes all shell-fish. they are soft-bodied, bilaterally symmetrical animals, without definite segments. the shells, on account of being formed of carbonate of lime on an organic basis, are often found preserved in fossiliferous strata. arthropoda.-- the seventh group, the arthropoda, or joint-footed animals, are distinguished by their segmented, lateral limbs, and by having a body composed of a series of segments or somites. the body and appendages are usually protected by a horny covering, the 'exoskeleton.' the group of the trilobites played an important part in the first era of the formation of the earth's crust; whilst the other groups were more sparsely represented in earlier geological times, but became more and more predominant until the present day. vertebrata.-- the great group of the vertebrata comes last, with its chief characteristic of the backbone structure, which advances in complexity from the fishes to the higher mammals. =a simplified classification of the vegetable kingdom.= series. | forms found fossil. ---------------------+---------------------------------- i.--thallophyta |sea-weeds: as corallines and | calcareous algae. | ii.--bryophyta |mosses, liverworts. | iii.--pteridophyta |fern-like plants, as horse-tails, | club-mosses and true ferns. | iv.--pteridospermeae|oldest seed-bearing plants, | with fern-like foliage. | v.--gymnospermeae |plants with naked seeds, as cycads | (fern-palms), ginkgo | (maiden-hair tree), and | conifers (pine trees). | vi.--angiospermeae |flowering plants, as grasses, | lilies and all ordinary trees | and plants. =characters of the plant series.= thallophyta.-- the first series, the thallophytes, are simple unicellular plants, and occupy the same position in the vegetable kingdom as the protozoa do in the animal kingdom. fossil remains of these organisms seem to be fairly well distributed throughout the entire geological series, but, owing to the soft structure of the fronds in most of the types, it is often a matter of doubt whether we are dealing with a true thallophyte or not. many of the so-called sea-weeds (fucoids) may be only trails or markings left by other organisms, as shell-fish and crustaceans. bryophyta.-- the second series, the bryophytes or moss plants, are represented in the fossil state by a few unimportant examples. pteridophyta.-- the third series, the pteridophytes, includes the ferns found from the devonian up to the present day, horse-tails and allied forms, like _equisetites_, and the club-mosses and _lepidodendron_ of the carboniferous period in various parts of the world. pteridospermeae.-- the fourth series, the pteridospermeae, comprises some of the earliest seed-bearing plants, as _alethopteris_ and _neuropteris_. they occur in rocks of upper palaeozoic age as far as known. gymnospermeae. the fifth series, the gymnospermeae, contains the most important types of plants found fossil, especially those of the primary and secondary rocks: they were more abundant, with the exception of the coniferae, in the earlier than in the more recent geological periods. angiospermeae.-- the sixth series, the angiospermeae, comprises all the flowering trees and plants forming the bulk of the flora now living, and is divided into the kinds having single or double seed-leaves (monocotyledones the dicotyledones respectively). this important group came into existence towards the close of the cretaceous period simultaneously with the higher mammals, and increased in abundance until modern times. chapter iii. the geological epochs: and the time range of fossils. =superposition of strata.--= fossils are chiefly found in rocks which have been formed of sediments laid down in water, such as sandstone, shale and most limestones. these rocks, broadly speaking, have been deposited in a horizontal position, though really slightly inclined from shore to deep-water. one layer has been formed above another, so that the oldest layer is at the bottom, and the newest at the top, of the series (fig. ). let us, for instance, examine a cliff showing three layers: the lower, a sandstone, we will call a; the intermediate, a shale or clay bed, b; and the uppermost, a limestone or marl, c (fig. ). in forming a conclusion about the relative ages of the beds, we shall find that a is always older than b, and b than c, provided no disturbance of the strata has taken place. for instance, the beds once horizontally deposited may have been curved and folded over, or even broken and thrust out of place, within limited areas; but occurrences like these are extremely rare. moreover, an examination of the surrounding country, or of deep cuttings in the neighbourhood, will tell us if there is any probability of this inversion of strata having taken place. [illustration: =fig. .--horizontal layers of fossiliferous clays and sands.= in sea cliff, torquay coast, victoria, looking towards bird rock. (_original_). ] [illustration: =fig. .--cliff-section to show superposition of strata.= a = sandstone. b = shale. c = limestone.] this law of superposition holds good throughout the mass of sedimentary rocks forming the crust of the earth. ( ). thus, the position of the strata shows the relative ages of the beds. =differences in fossil faunas.--= turning once again to our ideal cliff section, if we examine the fossils obtained from bed a, we shall find them differing in the number of kinds or species common to the other beds above and below. thus, there will be more species alike in beds a and b or in b and c. in other words the faunas of a and b are more nearly related than those of a and c. this is explained by the fact that there is a gradual change in specific forms as we pass through the time series of strata from below upwards; so that the nearer one collecting platform is to another, as a rule, the stronger is the community of species. =guide fossils.--= certain kinds of fossils are typical of particular formations. they are known as guide fossils, and by their occurrence help us to gain some idea of the approximate age of rocks widely separated by ocean and continent. thus we find fossils typical of the middle devonian rocks in europe, which also occur in parts of australia, and we therefore conclude that the australian rocks containing those particular fossils belong to the same formation, and are nearly of the same age. ( ). the included fossils, therefore, give evidence of the age of the beds. =value of lithological evidence.--= the test of age by rock-structure has a more restricted use, but is of value when taken in conjunction with the sequence of the strata and the character of their included fossils. to explain both the valuable and the uncertain elements of this last method as a determinant of age, we may cite, for instance, the upper ordovician slates of victoria and new south wales as an example of uniform rock formation; whilst the yellow mudstones and the grey limestones of the upper silurian (yeringian series) of the same states, are instances of diverse lithological structures in strata of similar age. a reference in the latter case to the assemblages of fossils found therein, speedily settles the question. ( ). hence, the structure and composition of the rocks (lithology), gives only partial evidence in regard to age. =strata vertically arranged.--= the stratigraphical series of fossiliferous sediments comprises bedded rocks from all parts of the world, which geologists arrange in a vertical column according to age. a general computation of such a column for the fossiliferous rocks of europe gives a thickness of about miles. this is equivalent to a mass of strata lying edgewise from melbourne to ringwood. the australian sediments form a much thicker pile of rocks, for they can hardly fall short of miles, or nearly the distance from melbourne to healesville. this vertical column of strata was formed during three great eras of time. the oldest is called the primary or palaeozoic ("ancient life"), in which the animals and plants are of primitive types. this is followed by the secondary or mesozoic ("middle life"), in which the animals and plants are intermediate in character between the palaeozoic and the later, cainozoic. the third era is the tertiary or cainozoic ("recent life"), in which the animals and plants are most nearly allied to living forms. these great periods are further subdivided into epochs, as the silurian epoch; and these again into stages, as the yeringian stage. vertical column of fossiliferous strata, australia. era. | epochs in | equivalent strata | europe. | in australia. -------------+---------------+------------------------------- | holocene | dunes, beaches, and shell-beds | | now forming. | | | pleistocene | raised beaches, river terraces, | | swamp deposits | | with diprotodon, cave | | breccias, helix sandstone. | | cainozoic | pliocene | upper.--estuarine beds of or | | bores in the murray basin, tertiary | | marine beds of (note ). | | limestone creek, glenelg | | river, vic. (werrikooian). | | | | lower.--kalimnan red | | sands (terrestrial) and | | shell marls (marine) of | | victoria, deep leads | | (fluviatile) in part, upper | | aldingan of south | | australia. -------------+---------------+------------------------------- cainozoic | miocene | deep leads in part: leaf-beds or | | of bacchus marsh, tertiary | | dalton and gunning. (continued). | | janjukian series of c. | | otway, spring creek, and | | table cape. batesford | | limestone. polyzoal | | rock of mt. gambier and | | the nullarbor plains. | | older cainozoic of murray | | basin, lower aldingan | | series of s. australia, | | corio bay and | | bairnsdale series. | | | oligocene | shelly clays and leaf-beds | | of the balcombian series | | at mornington; also | | shell-marls and clays | | with brown coal, altona | | bay, and lower beds at | | muddy creek, w. vict. | | | eocene | probably no representatives. -------------+---------------+------------------------------- | | mesozoic | cretaceous | upper.--leaf-beds of croydon, or | | q. desert sandstone, secondary | | q. radiolarian rock, n. | | territory. gin-gin chalk, | | w.a. | | | | lower.--rolling downs | | formn., q. lake eyre | | beds, s.a. | | | jurassic | marine.--geraldton, w.a. | | | | freshwater.--carbonaceous | | sandstone of s. | | gippsland, the wannon, | | c. otway and barrabool | | hills. ipswich series, q. | | mesozoic of tasmania, | | talbragar beds, n.s.w. | | | triassic | upper leaf-beds at bald | | hill, bacchus marsh, vict. | | hawkesbury series (parramatta | | shales, hawkesbury | | sandstone, narrabeen | | beds), n.s.w. burrum | | beds, q. -------------+---------------+------------------------------ palaeozoic | permian and | carbopermian (note ), or | carboniferous,| coal measures of new primary | upper | south wales, w. australia, | | queensland (gympie | | series) and tasmania. | | gangamopteris beds of | | bacchus marsh, vict. | | upper carboniferous of | | clarence town, n.s.w. | carboniferous,| fish and plant beds, | lower | mansfield, vict. grampian | | sandstone; avon | | river sandstone, vict. | | (?) star beds, queensland. | | lepidodendron | | beds of kimberley, w.a. | | (note ). | devonian | upper.--sandstones of iguana | | creek, with plant remains. | | lepidodendron | | beds with lingula, nyrang | | creek, n.s. wales. | | middle.--fossiliferous marbles | | and mudstones of | | buchan, bindi and tabberabbera, | | vict. rocks | | of the murrumbidgee, | | n.s. wales, and of burdekin, | | queensland. | silurian | upper.--(yeringian stage).--lilydale, | | loyola, thomson | | river, and waratah | | bay, vict.; bowning and | | yass (in part), n.s. | | wales; queensland. | | lower (melbournian | | stage).--melbourne, | | heathcote, vict.; bowning | | and yass (in part), | | n.s. wales. gordon r. | | limestone. | ordovician, | slates (graptolitic).--victoria | upper and | and new south | lower | wales. (?) gordon river | | limestone, tas., in part | | (note ). larapintine | | series of central australia. | cambrian | mudstones and limestones | | of tasmania, | | south australia, victoria | | and w. australia. | pre-cambrian | fossiliferous rocks doubtful; | | chiefly represented | | by schistose and other | | metamorphic rocks. .--the classification of the cainozoics as employed here is virtually the same as given by mccoy in connection with his work for the victorian geological survey. the writer has obtained further evidence to support these conclusions from special studies in the groups of the cetacea, mollusca and the protozoa. the alternative classification of the cainozoics as given by one or two later authors, introducing the useful local terminology of hall and pritchard for the various stages or assises is as follows:-- tate and dennant. | hall and pritchard. stages. | stages. | werrikooian pleistocene | werrikooian pliocene. pliocene | | kalimnan miocene | kalimnan miocene. | janjukian (?) oligocene | balcombian eocene. | balcombian eocene | janjukian | and aldingan eocene | aldingan eocene. (lower beds | in part at that loc.) | .--or permo-carboniferous. as the series is held by some authorities to partake of the faunas of both epochs, it is preferable to use the shorter word, which moreover gives the natural sequence. there is, however, strong evidence in favour of using the term permian for this important series. .--mr. w. s. dun regards the _lepidodendron_ beds of w. australia, new south wales and queensland as of upper devonian age. there is no doubt, from a broad view of the whole question as to the respective age of these beds in australia, that the one series is continuous, and probably represents the upper devonian and the lower carboniferous of the northern hemisphere. .--these limestones contain a fauna of brachiopods and corals which, at present, seems to point to the series as intermediate between the older silurian and the upper ordovician. vertical column of fossiliferous strata, new zealand. | epochs in | equivalent strata era. | europe. | in new zealand. ------------+------------------+---------------------- | holocene | river alluvium. beach | | sands and gravel. | | cainozoic | pleistocene | raised beaches. older gravel or | | drifts. tertiary | | moraines. boulder clays. | | | pliocene | upper.--petane series. } | | lower.--waitotara } wanganui | | and awatere series. } system. | | | miocene | oamaru series. | | | oligocene | waimangaroa series. ------------+------------------+--------------------------- | cretaceous | waipara series (of hutton). | | mesozoic | jurassic | mataura and putataka or | | series. secondary | | | triassic | wairoa, otapiri and kaihiku | | series. ------------+------------------+----------------------------- | permian | aorangi (unfossiliferous) | | series. | | | (?)carboniferous | maitai series (with spirifer | | and productus.) | | | | (?)te anau series (unfossiliferous). palaeozoic | | or | silurian | wangapeka series. primary | | | ordovician | kakanui series (with lower | | ordovician graptolite | | facies). | | | cambrian | unfossiliferous. metamorphic | | schists of the maniototo | | series. .--based for the most part, but with some slight modifications, on prof. j. park's classification in "geology of new zealand," . [illustration: =fig. .= range-in-time of fossils in australasian sedimentary rocks. _e.m., del._] ] [illustration: =fig. .--skeleton of diprotodon australis, owen.= uncovered in morass at lake callabonna, south australia. (_by permission of dr. e. c. stirling_). ] chapter iv. how fossils are found: and the rocks they form. as already noticed, it is the hard parts of buried animals and plants that are generally preserved. we will now consider the groups of organisms, one by one, and note the particular parts of each which we may reasonably expect to find in the fossil state. mammals.--the bones and teeth: as the _diprotodon_ remains of lake callabonna in south australia (fig. ), of west melbourne swamp, victoria, and the darling downs, queensland. rarely the skin, as in the carcases of the frozen mammoth of the tundras of northern siberia; or the dried remains of the _grypotherium_ of south american caves. [illustration: =fig. .--bird bones.= exposed on sand-blow at seal bay, king island. (_photo by c. l. barrett_). ] [illustration: =fig. .--impression of a bird's feather in ironstone.= about / nat. size. of cainozoic (? janjukian) age. redruth, victoria. (_nat. mus. coll._) ] [illustration: =fig. .--notochelone costata, owen sp. (anterior portion of carapace.)= about / nat. size. a marine turtle from the lower cretaceous of flinders river, queensland. (_nat. mus. coll._) ] birds:--bones: as the moa bones of new zealand and the emu bones of the king island sand-dunes (fig. ). very rarely the impressions of the feathers of birds are found, as in the ironstone occurring in the wannon district of victoria (fig. ), and others in fine clays and marls on the continent of europe and in england. fossil eggs of sea-birds are occasionally found in coastal sand-dunes of holocene age. reptiles.--skeletons of fossil turtles (_notochelone_) are found in queensland (fig. ). whole skeletons and the dermal armour (spines and bony plates) of the gigantic, specialised reptiles are found in europe, north america, and in other parts of the world. fishes.--whole skeletons are sometimes found in sand and clay rocks, as in the trias of gosford, new south wales (fig. ), and in the jurassic of south gippsland. the ganoid or enamel-scaled fishes are common fossils in the devonian and jurassic, notably in germany, scotland and canada: and they also occur in the sandy mudstone of the lower carboniferous of mansfield, victoria. insects.--notwithstanding their fragility, insects are often well preserved as fossils, for the reason that their skin and wings consist of the horny substance called chitin. the tertiary marls of europe are very prolific in insect remains (fig. ). from the miocene beds of florissant, colorado, u.s.a., several hundred species of insects have been described. [illustration: =fig. .= =a fossil fish with ganoid scales (pristisomus crassus, a.s. woodw.).= about / nat. size. trias (hawkesbury series), of gosford, new south wales. (_nat. mus. coll._) ] [illustration: =fig .--a fossil insect (tipula sp.) in amber.= nat. size. oligocene beds; baltic prussia. (_f.c. coll._) ] [illustration: =fig. .--a fossil lobster (thalassina emerii, bell).= slightly reduced. from the pleistocene of port darwin, northern territory. (_nat. mus. coll._) ] [illustration: =fig. .--an ammonite (desmoceras flindersi, mccoy sp.)= half nat. size. showing complex sutures. l. cretaceous: marathon, flinders river, queensland. (_nat. mus. coll._) ] crustacea.--the outer crust, or exoskeleton, of these animals is often hard, being formed of a compound of carbonate and phosphate of lime on an organic, chitinous base. the earliest forms of this group were the trilobites, commencing in cambrian times, and of which there is a good representative series in australian rocks. remains of crabs and lobsters are found in the various cainozoic deposits in australia (fig. ), and also in the jurassic in other parts of the world. mollusca.--the cuttle-fish group (cephalopoda, "head-footed"), is well represented by the nautilus-like, but straight _orthoceras_ shells commencing in ordovician times, and, in later periods, by the beautiful, coiled ammonites (fig. ). the true cuttle-fishes possess an internal bone, the sepiostaire, which one may see at the present day drifted on to the sand at high-water mark on the sea-shore. the rod-like belemnites are of this nature, and occur abundantly in the australian cretaceous rocks of south australia and queensland (fig. ). [illustration: =fig. . belemnites (belemnites diptycha, mccoy).= / nat. size. lower cretaceous. central south australia. (_nat. mus. coll._) ] [illustration: =fig. .--a group of lamp shells (magellania flavescens, lam. sp.)= attached to a polyzoan. about / nat. size. dredged from westernport, victoria. (_c.j. gabriel coll._) ] elephant-tusk shells (scaphopoda) are frequent in our tertiary beds: they are also sparingly found in the cretaceous, and some doubtful remains occur in the palaeozoic strata of australia. the shells of the ordinary mollusca, such as the snails, whelks, mussels, and scallops, are abundant in almost all geological strata from the earliest periods. their calcareous shells form a covering which, after the decay of the animal within, are from their nature among the most easily preserved of fossil remains. there is hardly an estuary bed, lake-deposit, or sea-bottom, but contains a more or less abundant assemblage of these shell-fish remains, or testacea as they were formerly called ("testa," a shell or potsherd). we see, therefore, the importance of this group of fossils for purposes of comparison of one fauna with another (_antea_, fig. ). the chitons or mail-shells, by their jointed nature, consisting of a series of pent-roof-shaped valves united by ligamental tissue, are nearly always represented in the fossil state by separate valves. fossil examples of this group occur in australia both in palaeozoic rocks and, more numerously, in the cainozoic series. [illustration: =fig. .--zoarium of a living polyzoan. (retepora)= / nat. size. flinders, victoria. (_f.c. coll._) ] [illustration: =fig. .--a fossil polyzoan (macropora clarkei, t. woods, sp.)= about / nat. size. cainozoic (balcombian). muddy creek, victoria. (_f.c. coll._) ] molluscoidea.--the brachiopods or lamp-shells consist generally of two calcareous valves as in the true mollusca (fig. ), but are sometimes of horny texture. like the previous class, they are also easily preserved as fossils. they possess bent, loop-like or spiral arms, called brachia, and by the movement of fine ciliated (hair-like) processes on their outer edges conduct small food particles to the mouth. the brachia are supported by shelly processes, to which are attached, in the spirifers, delicate spirally coiled ribbons. these internal structures are often beautifully preserved, even though they are so delicate, from the fact that on the death of the animal the commissure or opening round the valves is so tightly closed as to prevent the coarse mud from penetrating while permitting the finer silt, and more rarely mineral matter in solution, to pass, and subsequently to be deposited within the cavity. at the murray river cliffs in south australia, a bed of cainozoic limestone contains many of these brachiopod shells in a unique condition, for the hollow valves have been filled in with a clear crystal of selenite or gypsum, through which may be seen the loop or brachial support preserved in its entirety. the sea-mats or polyzoa, represented by _retepora_ (the lace-coral) (fig. ) and _flustra_ (the sea-mat) of the present sea-shore, have a calcareous skeleton, or zoarium, which is easily preserved as a fossil. polyzoa are very abundant in the cainozoic beds of australia, new zealand, and elsewhere (fig. ). in the mesozoic series, on the other hand, they are not so well represented; but in europe and north america they play an important part in forming the cretaceous and some jurassic strata by the abundance of their remains. worms (vermes).--the hard, calcareous tubes of sea-worms, the polychaeta ("many bristles") are often found in fossiliferous deposits, and sometimes form large masses, due to their gregarious habits of life; they also occur attached to shells such as oysters (fig. ). the burrows of the wandering worms are found in silurian strata in australia; and the sedentary forms likewise occur from the devonian upwards. echinodermata.--sea-urchins (echinoidea) possess a hard, calcareous, many-plated test or covering and, when living are covered with spines (fig. ). both the tests and spines are found fossil, the former sometimes whole when the sediment has been quietly thrown down upon them; but more frequently, as in the shepherd's crown type (_cidaris_), are found in disjointed plates, owing to the fact that current action, going on during entombment has caused the plates to separate. the spines are very rarely found attached to the test, more frequently being scattered through the marl or sandy clay in which the sea-urchins are buried. the best conditions for the preservation of this group is a marly limestone deposit, in which case the process of fossilisation would be tranquil (fig. ). [illustration: =fig. .--fossil worm tubes (? serpula.)= attached to a pecten. slightly enlarged. cainozoic (balcombian). muddy creek, hamilton, victoria. (_f. c. coll._) ] [illustration: =fig. .= =a regular sea-urchin (strongylocentrotus erythrogrammus, val.)= about / nat. size. showing spines attached. living. victoria. (_f. c. coll._) ] [illustration: =fig. .--a fossil sea-urchin (linthia antiaustralis, tate).= test denuded of spines. about / nat. size. cainozoic (janjukian): curlewis, victoria. (_nat. mus. coll._) ] [illustration: =fig. .--ophioderma egertoni, broderip, sp.= about / nat. size. a brittle star from the lias of seaton, devon, england. (_nat. mus. coll._) ] the true starfishes (asteroidea), are either covered with calcareous plates, or the skin is hardened by rough tubercles; and these more lasting portions are preserved in rocks of all ages. the shape of the animal is also often preserved in an exquisite manner in beds of fine mud or clay. the brittle-stars (ophiuroidea) have their body covered with hard, calcareous plates. their remains are found in rocks as old as the ordovician in bohemia but their history in australia begins with the silurian period (fig. ). from thence onward they are occasionally found in successive strata in various parts of the world. the bag-like echinoderms (cystidea) form a rare group, restricted to palaeozoic strata. the plates of the sack, or theca, and those of the slender arms are calcareous, and are capable of being preserved in the fossil state. a few doubtful remains of this group occur in australia. the bud-shaped echinoderms (blastoidea) also occur chiefly in devonian and carboniferous strata. this is also a rare group, and is represented by several forms found only in new south wales and queensland. the well known and beautiful fossil forms, the stone-lilies (crinoidea) have a very extended geological history, beginning in the cambrian; whilst a few species are living in the ocean at the present day. the many-jointed skeleton lends itself well to fossilisation, and remains of the crinoids are common in australia mainly in palaeozoic strata (fig. ). in europe they are found abundantly also in jurassic strata, especially in the lias. [illustration: =fig. .= =a fossil crinoid (taxocrinus simplex, phillips sp.)= about / nat. size. wenlock limestone (silurian), dudley, england. (_nat. mus. coll._) ] [illustration: =fig. .--graptolites on slate (tetragraptus fruticosus, j. hall, sp.)= nat. size. lower ordovician. bendigo, victoria. (_nat. mus. coll._) ] [illustration: =fig. .= =polished vertical section of a stromatoporoid. (actinostroma).= nat. size. middle devonian. south devon, england. (_f.c. coll._) ] hydrozoa.--the graptolites ("stone-writing") have a chitinous skin (periderm) to the body or hydrosome, which is capable of preservation to a remarkable degree; for their most delicate structures are preserved on the surfaces of the fine black mud deposits which subsequently became hardened into slates. in australia graptolites occur from the base of the ordovician to the top of the silurian (fig. ). another section of the hydrozoa is the stromatoporoidea. these are essentially calcareous, and their structure reminds one of a dense coral. the polyps build their tiers of cells (coenosteum) in a regular manner, and seem to have played the same part in the building of ancient reefs in silurian, devonian and carboniferous times as the millepora at the present day (fig. ). [illustration: =fig. .--fossil corals (favosites).= photograph of a polished slab, / nat. size. in devonian limestone, buchan, victoria.] [illustration: =fig. .--siliceous skeleton of a living hexactinellid sponge.= probably chonelasma. Ã� . mauritius. (viewed in two directions.) (_f.c. coll._) ] anthozoa.--the true corals have a stony skeleton, and this is capable of easy preservation as a fossil. there is hardly any fossiliferous stratum of importance which has not its representative corals. in australia their remains are especially abundant in the silurian, devonian (fig. ), and carboniferous formations, and again in the oligocene and miocene. sponges.--the framework of the sponge may consist either of flinty, calcareous, or horny material (fig. ). the two former kinds are well represented in our australian rocks, the first appearing in the lower ordovician associated with graptolites, and again in the cretaceous and tertiary rocks (fig. ); whilst the calcareous sponges are found in silurian strata, near yass, and again in the cainozoic beds of flinders, curlewis and mornington in victoria. [illustration: =fig. .= =spicules of a siliceous sponge (ecionema newberyi, mccoy sp.)= highly magnified. cainozoic shell-marl. altona bay coal-shaft.] [illustration: =fig. .= =nummulites (n. gizehensis ehr. var. champollioni, de la harpe).= about nat. size. middle eocene limestone. cyrene, northern africa. (_coll. by dr. j. w. gregory_). ] protozoa.--the important and widely-distributed group of the foraminifera ("hole-bearers") belonging to the lowest phylum, the protozoa, generally possess a calcareous shell. the tests range in size from tiny specks of the fiftieth of an inch in diameter, to the giant nummulite, equalling a five shilling piece in size (fig. ). their varied and beautiful forms are very attractive, but their great interest lies in their multifarious distribution in all kinds of sediments: they are also of importance because certain of the more complex forms indicate distinct life zones, being restricted to particular strata occurring in widely-separated areas. [illustration: =fig. .--siliceous skeletons of radiolaria.= Ã� . late cainozoic age. bissex hill, barbados, west indies. (_f.c. coll._) ] members of the allied order of the radiolaria have a flinty shell (fig. ); and these organisms are often found building up siliceous rocks such as cherts (fig. ). plants.--the harder portions of plants which are found in the fossil state are,--the wood, the coarser vascular (vessel-bearing) tissue of the leaves, and the harder parts of fruits and seeds. fossil wood is of frequent occurrence in palaeozoic, mesozoic and cainozoic strata in australia, as, for instance, the wood of the trees called _araucarioxylon_ and _dadoxylon_ in the coal measures of new south wales (see _antea_, fig. ). [illustration: =fig. .--radiolaria in siliceous limestone.= Ã� . middle devonian: tamworth, new south wales. (_from prof. david's collection_). ] [illustration: =fig. .--travertin limestone with leaves of beech (fagus).= nat. size. pleistocene: near hobart, tasmania. (_nat. mus. coll._) ] fossil leaves frequently occur in pipe-clay beds, as at berwick, victoria, and in travertine from near hobart, tasmania (fig. ). fossil fruits are found in abundance in the ancient river gravels at several hundreds of feet below the surface, in the "deep leads" of haddon, victoria, and other localities in new south wales, queensland and tasmania. [illustration: =fig. --freshwater limestone with shells (bulinus).= about / nat. size. mount arapiles, western victoria. (_nat. mus. coll._) ] [illustration: =fig. .--fossiliferous mudstone of silurian (yeringian) age.= with brachiopods. about / nat. size. near lilydale, victoria. (_f.c. coll._) ] fossiliferous rocks. section i.--argillaceous rocks. under this head are placed the muds, clays, mudstones, shales and slates. muds are usually of a silty nature, that is, containing a variable proportion of sand (quartz) grains. such are the estuarine muds of pleistocene and recent age, containing brackish water foraminifera and ostracoda, and those shells of the mollusca usually found associated with brackish conditions. lacustrine mud can be distinguished by the included freshwater shells, as _limnaea_, _coxiella_ (brackish), _cyclas_ and _bulinus_, as well as the freshwater ostracoda or cyprids (fig. ). clays are tenacious mud deposits, having the general composition of a hydrous silicate of alumina with some iron. when a clay deposit tends to split into leaves or laminae, either through moderate pressure or by the included fossil remains occupying distinct planes in the rock, they are called shales. clays and shales of marine origin are often crowded with the remains of mollusca. the shells are sometimes associated with leaves and other vegetable remains, if forming part of an alternating series of freshwater and marine conditions. an example of this type of sediments is seen in the mornington beds of the balcombian series in victoria. mudstone is a term applied to a hardened clay deposit derived from the alteration of an impure limestone, and is more often found in the older series of rocks. mudstones are frequently crowded with fossils, but owing to chemical changes within the rock, the calcareous organisms are as a rule represented by casts and moulds. at times these so faithfully represent the surface and cavities of the organism that they are almost equivalent to a well preserved fossil (fig. ). slate.--when shale is subjected to great pressure, a plane of regular splitting called cleavage is induced, which is rarely parallel to the bedding plane or surface spread out on the original sea-floor: the cleavage more often taking place at an appreciable angle to the bedding plane. the graptolitic rocks of victoria are either shales or slates, according to the absence or development of this cleavage structure in the rock. section ii.--siliceous rocks. in this group are comprised all granular quartzose sediments, and organic rocks of flinty composition. sandstones.--although the base of this type of rock is formed of quartz sand, it often contains fossils. owing to its porous nature, percolation of water containing dissolved co_{ } tends to bring about the solution of the calcareous shells, with the result that only casts of the shells remain. flints and cherts.--these are found in the form of nodules and bands in other strata, principally in limestone. in europe, flint is usually found in the chalk formation, whilst chert is found in the lower greensands, the jurassics, the carboniferous limestone and in cambrian rocks. in australia, flint occurs in the miocene or polyzoal-rock formation of mount gambier, cape liptrap and the mallee borings. flint is distinguished from chert by its being black in the mass, often with a white crust, and translucent in thin flakes; chert being more or less granular in texture and sub-opaque in the mass. both kinds appear to be formed as a pseudomorph or replacement of a portion of the limestone stratum by silica, probably introduced in solution as a soluble alkaline silicate. both flint and chert often contain fossil shells and other organic remains, such as radiolaria and sponge-spicules, which can be easily seen with a lens in thin flakes struck off by the hammer. diatomite is essentially composed of the tiny frustules or flinty cases of diatoms (unicellular algae), usually admixed with some spicules of the freshwater sponge, _spongilla_. it generally forms a layer at the bottom of a lake bed (fig. ). [illustration: =fig. .--diatomaceous earth. (post-tertiary).= containing freshwater forms, as pinnularia, cocconeis and synedra. Ã� . talbot, victoria.] section iii.--calcareous rocks. limestones formed by organisms.--organic limestones constitute by far the most important group of fossiliferous rocks. rocks of this class are composed either wholly of carbonate of lime, or contain other mineral matter also, in varying proportion. many kinds of limestones owe their origin directly to the agency of animals or plants, which extracted the calcareous matter from the water in which they lived in order to build their hard external cases, as for example the sea-urchins; or their internal skeletons, as the stony corals. the accumulated remains of these organisms are generally compacted by a crystalline cement to form a coherent rock. the chief groups of animals and plants forming such limestone rocks are:-- (a) _foraminifera._--example. foraminiferal limestone as the nummulitic limestone of the pyramids of egypt, or the _lepidocyclina_ limestone of batesford, near geelong, victoria (fig. ). [illustration: =fig. .= =limestone composed of polyzoa and foraminifera (lepidocyclina).= Ã� . cainozoic (janjukian). batesford, near geelong, victoria. (_f.c. coll._) ] (b) _corals._--ex. "madrepore limestone," or devonian marble, with _pachypora_. also the lilydale limestone, with _favosites_, of silurian age, victoria (fig. ). [illustration: =fig. .--a fossil coral (favosites grandipora).= / nat. size. from the silurian of lilydale, victoria. (_f.c. coll._). ] [illustration: =fig. .--polished slab of marble formed of joints of crinoids.= about / nat. size. silurian. toongabbie, gippsland, victoria. (_nat. mus. coll._) ] (c) _stone-lilies._--ex. crinoidal or entrochial limestone, silurian, toongabbie, victoria (fig. ). also the carboniferous or mountain limestone, derbyshire, england. (d) _worm-tubes.-_-ex. serpulite limestone of hanover, germany. _ditrupa_ limestone of torquay and wormbete creek, victoria. (e) _polyzoa._---ex. polyzoal limestone, as the so-called coralline crag of suffolk, england; and the polyzoal rock of mount gambier, s. australia. (f) _brachiopoda._--ex. brachiopod limestone of silurian age, dudley, england. _orthis_ limestone of cambrian age, dolodrook river, n. e. gippsland. (g) _mollusca._--ex. shell limestone, as the _turritella_ bed of table cape, tasmania, and of camperdown, victoria (fig. ), or the purbeck marble of swanage, dorset, england. [illustration: =fig. .--turritella limestone.= (t. acricula, tate); / nat. size. cainozoic. lake bullen merri, near camperdown, victoria.] [illustration: =fig. .--limestone composed of the valves of an ostracod (cypridea).= upper jurassic. Ã� . swanage, dorset, england.] (h) _ostracoda._--ex. cypridiferous limestone, formed of the minute valves of the bivalved ostracoda, as that of durlston, dorset, england (fig. ). (i) _caddis fly larvae._--ex. indusial limestone, formed of tubular cases constructed by the larvae of the caddis fly (_phryganea_). occurs at durckheim, rhine district, germany. (j) _red seaweeds._--ex. nullipore limestone, formed by the stony thallus (frond) of the calcareous sea-weed _lithothamnion_, as in the leithakalk, a common building stone of vienna. (k) _green seaweeds._--ex. _halimeda_ limestone, forming large masses of rock in the late cainozoic reefs of the new hebrides (fig. ). (l) (?) _blue-green seaweeds._--ex. _girvanella_ limestone, forming the peagrit of jurassic age, of gloucester, england. section iv.--carbonaceous and miscellaneous rocks. coals and kerosene shales (cannel coal).--these carbonaceous rocks are formed in much the same way as the deposits in estuaries and lagoon swamps. they result from the sometimes vast aggregation of vegetable material (leaves, wood and fruits), brought down by flooded rivers from the surrounding country, which form a deposit in a swampy or brackish area near the coast, or in an estuary. layer upon layer is thus formed, alternating with fine mud. the latter effectually seals up the organic layers and renders their change into a carbonaceous deposit more certain. when shale occurs between the coal-layers it is spoken of as the under-clay, which in most cases is the ancient sub-soil related to the coal-layer immediately above. it is in the shales that the best examples of fossil ferns and other plant-remains are often found. the coal itself is composed of a partially decomposed mass of vegetation which has become hardened and bedded by pressure and gradual drying. spore coals are found in thick deposits in some english mines, as at burnley in yorkshire. they result from the accumulation of the spores of giant club-mosses which flourished in the coal-period. they are generally referred to under the head of cannel coals. the "white coal" or tasmanite of the mersey basin in tasmania is an example of an impure spore coal with a sandy matrix (fig. ). [illustration: =fig. .= =rock composed of the calcareous joints of halimeda (a green sea-weed).= about / nat. size. late cainozoic. reef-rock. malekula, new hebrides. (_coll. by dr. d. mawson._) ] [illustration: =fig. .--thin slices of "white coal" or "tasmanite," showing crushed megaspores.= Ã� . carbopermian. latrobe, tasmania. (_f. c. coll._) ] [illustration: =fig. .--thin slice of "kerosene shale."= Ã� . carbopermian. hartley, new south wales. (_f. c. coll._) ] [illustration: =fig. .--bone bed, with fish and reptilian remains.= about / nat. size. (rhaetic). aust cliff, gloucestershire, england. (_nat. mus. coll._) ] the kerosene shale of new south wales is related to the torbanite of scotland and central france. it occurs in lenticular beds between the bituminous coal. it is a very important deposit, commercially speaking, for it yields kerosene oil, and is also used for the manufacture of gas. the rock is composed of myriads of little cell-bodies, referred to as _reinschia_, and first supposed to be allied to the freshwater alga, _volvox_; but this has lately been questioned, and an alternative view is that they may be the megaspores of club-mosses (fig. ). the coals of jurassic age in australia are derived from the remains of coniferous trees and ferns; and some beautiful examples of these plants may often be found in the hardened clay or shale associated with the coal seams. the brown coals of cainozoic or tertiary age in australia are still but little advanced from the early stage, lignite. the leaves found in them are more or less like the present types of the flora. the wood is found to be of the cypress type (_cupressinoxylon_). in new zealand, however, important deposits of coal of a more bituminous nature occur in the oligocene of westport and the grey river valley, in the nelson district. bone beds.--the bones and excreta of fish and reptiles form considerable deposits in some of the sedimentary formations; especially those partly under the influence of land or swamp conditions. they constitute a kind of conglomerate in which are found bone-fragments and teeth (fig. ). these bone-beds are usually rich in phosphates, and are consequently valuable as a source of manure. the miocene bone-bed with fish teeth at florida, u.s.a., is a notable example. the nodule bed of the victorian cainozoics contains an assemblage of bones of cetaceans (whales, etc.). [illustration: =fig. .--bone breccia, with remains of marsupials.= about / nat. size. pleistocene. limeburners point, geelong, victoria. (_nat. mus. coll._) ] bone breccias.--these are usually formed of the remains of the larger mammals, and consist of a consolidated mass of fragments of bones and teeth embedded in a calcareous matrix. bone-breccias are of frequent occurrence on the floors of caves which had formerly been the resort of carnivorous animals, and into which they dragged their prey. the surface water percolating through the overlying calcareous strata dissolved a certain amount of lime, and this was re-deposited on the animal remains lying scattered over the cave floor. a deposit so formed constitutes a stalagmite or floor encrustation. as examples of bone-breccias we may refer to the limestone at limeburners point, geelong (fig. ); and the stalagmitic deposits of the buchan caves. ironstone.--rocks formed almost entirely of limonite (hydrated peroxide of iron) are often due to the agency of unicellular plants known as diatoms, which separate the iron from water, and deposit it as hydrous peroxide of iron within their siliceous skeletons. in norway and sweden there are large and important deposits of bog iron-ore, which have presumably been formed in the beds of lakes. [illustration: =fig. .= =cainozoic ironstone with leaves (banksia ? marginata, cavanilles).= slightly enlarged. below wannon falls, redruth, victoria.] clay ironstone nodules (sphaerosiderite) have generally been formed as accretions around some decaying organic body. many clay ironstone nodules, when broken open, reveal a fossil within, such as a coprolitic body, fern frond, fir-cone, shell or fish. oolitic ironstones are composed of minute granules which may have originally been calcareous grains, formed by a primitive plant or alga, but since replaced by iron oxide or carbonate. the tertiary ironstone of western victoria is found to contain leaves, which were washed into lakes and swamps (fig. ); and the ferruginous groundmass may have been originally due to the presence of diatoms, though this yet remains to be proved. part ii.--systematic palaeontology. chapter v. fossil plants. =cambrian plants.--= the oldest australian plant-remains belong to the genus _girvanella_. this curious little tubular unicellular organism, once thought to be a foraminifer, shows most affinity with the blue-green algae (cyanophyceae), an important type of plant even now forming calcareous deposits such as the calcareous grains on the shores of the salt lake, utah, and the pea-grit of the carlsbad hot springs. _girvanella problematica_ occurs in the lower cambrian limestones of south australia, at ardrossan and elsewhere. =silurian plants.--= amongst silurian plants may be mentioned the doubtful sea-weeds known as _bythotrephis_. their branch-like impressions are fairly common in the mudstones of silurian age found in and around melbourne. they generally occur in association with shallow-water marine shells and crustacea of that period. the genus _girvanella_ before mentioned is also found in the silurian (yeringian) of lilydale and the tyers river limestone, victoria (fig. ). [illustration: =fig. .--section through pellet of girvanella conferta=, chapm. Ã� . from the silurian (yeringian) limestone of tyers river, gippsland, victoria. (_nat. mus. coll._) ] _haliserites_ is a primitive plant of the type of the club-mosses so common in the rocks of the carboniferous period. this genus is found in some abundance in the yeringian stage of the silurian in gippsland (fig. ). [illustration: =fig. .--palaeozoic plants.= (approximate dimensions in fractions). a--bythotrephis tenuis, j. hall. silurian. victoria. b--haliserites dechenianus, göppert. silurian. victoria. c--cordaites australis, mccoy. upper devonian. victoria. d--sphenopteris iguanensis, mccoy. upper devonian. victoria. e--glossopteris browniana, brongniart. carbopermian. n.s.w. ] [illustration: =fig. .= =restoration of lepidodendron elegans.= (_after grand'eury._) ] [illustration: =fig. .= =lepidodendron australe, mccoy.= portion of stem showing leaf-cushions. slightly reduced. carboniferous. manilla river, co. darling, n.s.w. (_nat. mus. coll._) ] =devonian and carboniferous plants.--= [illustration: =fig. .--upper palaeozoic plants.= a--rhacopteris inaequilatera, göppert sp. up. carboniferous. stroud, new south wales. (_after feistmantel_). b--gangamopteris spatulata, mccoy. carbopermian. bacchus marsh, victoria.] plant-life was not abundant, however, until upper devonian and carboniferous times. in the rocks of these periods we meet with the large strap-shaped leaves of _cordaites_ and a fern, _sphenopteris_, in the first-named series; and the widely distributed _lepidodendron_ with its handsome lozenge-scarred stems in the later series (fig. ). _cordaites_ has been found in victoria in the iguana creek beds (upper devonian), and it also probably occurs at the same horizon at nungatta, new south wales. _lepidodendron_ occurs in the lower carboniferous sandstone of victoria and queensland (fig. ): in new south wales it is found at mt. lambie, goonoo, tamworth and copeland in beds generally regarded as upper devonian. both of these plants are typical of carboniferous (coal measure) beds in europe and north america. the fern _rhacopteris_ is characteristic of upper carboniferous shales and sandstones near stroud, and other localities in new south wales as well as in queensland (fig. ). these beds yield a few inferior seams of coal. _girvanella_ is again seen in the oolitic limestones of carboniferous age in queensland and new south wales. =carbopermian plants.--= the higher division of the australian carboniferous usually spoken of as the permo-carboniferous, and here designated the carbopermian (see footnote , page ), is typified by a sudden accession of plant forms, chiefly belonging to ferns of the _glossopteris_ type. the lingulate or tongue-shaped fronds of this genus, with their characteristic reticulate venation, are often found entirely covering the slabs of shale intercalated with the coal seams of new south wales; and it is also a common fossil in tasmania and western australia. the allied form, _gangamopteris_, which is distinguished from _glossopteris_ by having no definite midrib, is found in beds of the same age in victoria, new south wales, and tasmania. these plant remains are also found in india, south africa, south america and the falkland islands. this wide distribution of such ancient ferns indicates that those now isolated land-surfaces were once connected, forming an extensive continent named by prof. suess "gondwana-land," from the gondwana district in india (fig. ). [illustration: _e. m. del._ (_after j. w. gregory_). =fig. .--map of the world in the upper carboniferous era.= ] =triassic plants.--= the widely distributed pinnate fern known as _thinnfeldia_ is first found in the trias; in the narrabeen shales near manly, and the hawksbury sandstone at mount victoria, new south wales. it is also a common fossil of the jurassic of south gippsland, and other parts of victoria. the grass-like leaves of _phoenicopsis_ are frequently met with in triassic strata, as in the upper series at bald hill, bacchus marsh, and also in tasmania. the large banana-palm-like leaves of _taeniopteris_ (_macrotaeniopteris_) are common to the triassic and lower jurassic beds of india: they are also met with in new zealand, and in the upper beds at bald hill, bacchus marsh. [illustration: =fig. .--mesozoic plants.= a--thinnfeldia odontopteroides. morris sp. trias. n.s. wales. b--cladophlebis denticulata, brongn. sp. var. australis, morr. jurassic, victoria. c--taeniopteris spatulata, mcclell. var. daintreei, mccoy. jurassic, victoria. d--brachyphyllum gippslandicum, mccoy. jurassic, victoria. e--ginkgo robusta, mccoy. jurassic, victoria. ] =jurassic plants.--= the jurassic flora of australasia is very prolific in plant forms. these range from liverworts and horse-tails to ferns and conifers. the commonest ferns were _cladophlebis_, _sphenopteris_, _thinnfeldia_ and _taeniopteris_. the conifers are represented by _araucarites_ (cone-scales, leaves and fruits), _palissya_ and _brachyphyllum_ (fig. ). the _ginkgo_ or maiden-hair tree, which is still living in china and japan, and also as a cultivated plant, was extremely abundant in jurassic times, accompanied by the related genus, _baiera_, having more deeply incised leaves; both genera occur in the jurassic of s. gippsland, victoria, and in queensland. the jurassic flora of australasia is in many respects like that of the yorkshire coast near scarborough. in new zealand this flora is represented in the mataura series, in which there are many forms identical with those of the australian jurassic, and even of india. =cretaceous plants.--= an upper cretaceous fern, (?) _didymosorus gleichenioides_, is found in the sandstones of the croydon gold-field, north queensland. =plants of the cainozoic.--balcombian stage.--= the older part of the cainozoic series in australasia may be referred to the oligocene. these are marine beds with occasional, thick seams of lignite, and sometimes of pipe-clay with leaves, the evidence of river influence in the immediate neighbourhood. the fossil wood in the lignite beds appears to be a _cupressinoxylon_ or cypress wood. leaves referable to plants living at the present day are also found in certain clays, as at mornington, containing _eucalyptus precoriacea_ and a species of _podocarpus_. [illustration: =fig. .--cainozoic plants.= a--cinnamomum polymorphoides, mccoy. cainozoic. victoria. b--laurus werribeensis, mccoy. cainozoic. victoria. c--banksia campbelli, ettingsh. cainozoic. vegetable creek, n.s.w. d--fagus risdoniana, ettingsh. cainozoic. tasmania. e--spondylostrobus smythi, mueller. cainozoic. (deep leads), victoria. ] =miocene leaf-beds.--janjukian stage.--= later cainozoic deposits, evidently accumulated in lakes, and sometimes ferruginous, may be referred to the miocene. they are comparable in age with the janjukian marine beds of spring creek and waurn ponds in victoria. these occur far inland and occupy distinct basins, as at the wannon, bacchus marsh (maddingley), and pitfield plains. leaf-beds of this age occur also on the otway coast, victoria, containing the genera _coprosmaephyllum_, _persoonia_ and _phyllocladus_. in all probability the dalton and gunning leaf-beds of new south wales belong here. examples of the genera found in beds of this age are _eucalyptus_ (a species near _e. amygdalina_), _banksia_ or native honeysuckle, _cinnamomum_ or cinnamon, _laurus_ or laurel, and _fagus_ (_notofagus_) or beech (fig. ). in the leaf-beds covered by the older basalt on the dargo high plains, gippsland, leaves of the _ginkgo murrayana_ occur. in south australia several occurrences of leaf beds have been recorded, containing similar species to those found in the cainozoic of dalton and vegetable creek, new south wales. for example, _magnolia brownii_ occurs at lake frome, _bombax sturtii_ and _eucalyptus mitchelli_ at elizabeth river, and _apocynophyllum mackinlayi_ at arcoona. =fruits of the "deep leads."--= the deep leads of victoria, new south wales and tasmania probably begin to date from the period just named, for they seem to be contemporaneous with the "older gold drift" of victoria; a deposit sometimes containing a marine fauna of janjukian age. this upland river system persisted into lower pliocene times, and their buried silts yield many fruits, of types not now found in australia, such as _platycoila_, _penteune_ and _pleioclinis_, along with _cupressus_ (_spondylostrobus_) and _eucalyptus_ of the existing flora (fig. ). =pleistocene plants.--= the pleistocene volcanic tuffs of mount gambier have been shown to contain fronds of the living _pteris_ (_pteridium_) _aquilina_ or bracken fern, and a _banksia_ in every way comparable with _b. marginata_, a species of the native honeysuckle still living in the same district. [illustration: =fig. .--leaves of a fossil eucalyptus. (e. pluti, mccoy).= about / nat. size. from the cainozoic deep leads, daylesford, victoria. (_nat. mus. coll._) ] the siliceous valves of freshwater diatoms constitute the infusorial earths of victoria, queensland, new south wales and new zealand. the commonest genera met with are _melosira_, _navicula_, _cymbella_ (or _cocconema_), _synedra_, _tabellaria_, _stauroneis_ and _gomphonema_. they are, generally speaking, of pleistocene age, as they are often found filling hollows in the newer basalt flows. in victoria diatomaceous earths are found at talbot (see fig. ), sebastopol and lancefield; in queensland, at pine creek; in new south wales, at cooma, barraba, and the richmond river; and in new zealand at pakaraka, bay of islands. in the latter country there is also a marine diatomaceous rock in the oamaru series, of miocene age. common or characteristic fossils of the foregoing chapter. _girvanella problematica_, nicholson and etheridge. cambrian: s. australia. _bythotrephis tenuis_, j. hall. silurian: victoria. _haliserites dechenianus_, göppert sp. silurian and devonian: victoria. _cordaites australis_, mccoy. upper devonian: victoria. _lepidodendron australe_, mccoy. lower carboniferous: victoria and queensland. up. devonian: new south wales. _rhacopteris inaequilatera_, göppert sp. carboniferous: new south wales. _glossopteris browniana_, brongniart. carbopermian: new south wales, queensland, tasmania and w. australia. _gangamopteris spatulata_, mccoy. carbopermian: victoria, new south wales and tasmania. _thinnfeldia odontopteroides_, morris sp. triassic: new south wales. jurassic: victoria, queensland and tasmania. _cladophlebis denticulata._, brongn. sp., var. australis, morris. jurassic: queensland, new south wales, victoria, tasmania and new zealand. _taeniopteris spatulata_, mcclelland. jurassic: queensland, new south wales, victoria, and tasmania. (?) _didymosorus gleichenioides_, etheridge fil. upper cretaceous: queensland. _eucalyptus precoriacea_, deane. oligocene: victoria. _eucalyptus_, _banksia_, _cinnamomum_, _laurus_ and _fagus_. miocene: victoria, new south wales and tasmania. _spondylostrobus smythi_, von mueller. (fruits and wood). lower pliocene: victoria and tasmania. _pteris_ (_pteridium_) _aquilina_, linné, and _banksia_ cf. _marginata_, cavanilles. pleistocene: victoria and south australia. * * * * * literature. girvanella.--etheridge, r. jnr. trans. r. soc. s. australia, vol. xiii. , pp. , . etheridge, r. and card, g. geol. surv. queensland, bull. no. , , pp. , , . chapman, f. rep. austr. assoc. adv. sci., adelaide meeting ( ), , p. . devonian ferns and cordaites.--mccoy, f. prod. pal. vict. dec. v., , p. . dun, w. s. rec. geol. surv. new south wales, vol. v. pt. , , p. . lepidodendron.--mccoy, f. prod. pal. vict., dec. i. , p. . etheridge, r. jnr. rec. geol. surv, new south wales, vol. ii., pt. , , p. . idem, geol. and pal. queensland, , p. . carboniferous fungi.--etheridge, r. jnr. geol. surv. w.a., bull, no. , , pp. - . carboniferous ferns.--dun, w. s. rec. geol. surv. new south wales, vol. viii. pt. , , pp. - , pls. xxii. and xxiii. glossopteris.--feistmantel, o. mem. geol. surv. new south wales, pal. no. , . arber, n. cat. foss. plants, glossopteris flora, brit. mus., . gangamopteris.--mccoy, f. prod. pal. vict., dec. ii. , p. . jurassic plants.--mccoy, f. prod. pal. vic., dec. ii. , p. . woods, t. proc. linn. soc. new south wales, vol. viii. pt. i. , p. . etheridge, r. jnr. geol. pal. queensland, , p. . dun, w. s. (taeniopteris), rep. austr. asso. adv. sci., sydney, , pp. - . seward, a. c. rec. geol. surv. vic., vol. i. pt. , ; chapman, f. ibid., vol ii. pt. , ; vol. iii., pt. , . dun, w. s. rec. geol. surv. new south wales, vol. viii. pt. , , p. . older cainozoic plants.--mccoy, f. prod. pal. vic., dec. iv. , p. . ettingshausen, c. von. mem. geol. surv. new south wales, pal. no. , . idem, trans. new zealand inst., vol. xxiii. ( ), , p. . deane, h. rec. geol. surv. vict., vol. i. pt. , , pp. , . lower pliocene deep leads.--mccoy, f. prod. pal. vict., dec. iv. , p. . mueller, f. von. geol. surv. vic., new veg. foss., and . pleistocene and other diatom earths.--card, g. w. and dun, w. s., rec. geol. surv. new south wales, vol. v. pt. , , p. . chapter vi. fossil foraminifera and radiolaria. =protozoans, their structure.--= the animals forming the sub-kingdom protozoa ("lowliest animals"), are unicellular (one-celled), as distinguished from all the succeeding higher groups, which are known as the metazoa ("animals beyond"). the former group, protozoa, have all their functions performed by means of a simple cell, any additions to the cell-unit merely forming a repetitional or aggregated cell-structure. a familiar example of such occurs in pond-life, in the amoeba, a form which is not found fossilised on account of the absence of any hard parts or covering capable of preservation. foraminifera and radiolaria, however, have such hard parts, and are frequently found fossilised. =foraminifera: their habitats.--= the _foraminifera_ are a group which, although essentially one-celled, have the protoplasmic body often numerously segmented. the shell or test formed upon, and enclosing the jelly-like sarcode, may consist either of carbonate of lime, cemented sand-grains, or a sub-calcareous or chitinous (horny) covering. the foraminifera, with very few exceptions, as _mikrogromia_, _lieberkuehnia_, and some forms of _gromia_, are all marine in habit. some genera, however, as _miliolina_, _rotalia_ and _nonionina_, affect brackish water conditions. since foraminifera are of so lowly a grade in the animal kingdom, we may naturally expect to find their remains in the oldest known rocks that show any evidence of life. they are, indeed, first seen in rocks of cambrian age, although they have not yet been detected there in australian strata. =cambrian foraminifera.--= in parts of siberia and in the baltic provinces, both cambrian and ordovician rocks contain numerous glauconite casts of foraminifera, generally of the _globigerina_ type of shell. in england some middle cambrian rocks of shropshire are filled with tiny exquisitely preserved spiral shells belonging to the genus _spirillina_, in which all the characters of the test are seen as clearly as in the specimens picked out of shore-sand at the present day. =silurian foraminifera.--= the silurian rocks in all countries are very poor in foraminiferal shells, only occasional examples being found. in rocks of this age at lilydale, victoria, the genus _ammodiscus_, with fine sandy, coiled tests, is found in the cave hill limestone. so far as known, hardly any forms of this group occur in devonian strata, although some ill-defined shells have been found in the eifel, germany. =carboniferous foraminifera.--= the carboniferous rocks in many parts of the world yield an abundant foraminiferal fauna. such, for instance, are the _saccammina_ and _endothyra_ limestones of the north of england and the north of ireland. the australian rocks of this age have not afforded any examples of the group, since they are mainly of estuarine or freshwater origin. [illustration: =fig. .--palaeozoic and mesozoic foraminifera.= a--nubecularia stephensi, howchin. carbopermian. n.s.w. b--frondicularia woodwardi, howchin. carbopermian. n.s.w. c--geinitzina triangularis, chapman and howchin. carbopermian. n.s.w. d--valvulina plicata, brady. carbopermian. west australia. e--vaginulina intumescens, reuss. jurassic. west australia. f--flabellina dilatata, wisniowski. jurassic. west australia. g--marginulina solida, terquem. jurassic. west australia. h--frondicularia gaultina, reuss. cretaceous. west australia. ] =carbopermian foraminifera.--= in australia, as at pokolbin, new south wales, in the mersey river district, tasmania, and in the irwin river district, western australia, the permian rocks, or "permo-carboniferous" as they are generally called, often contain beds of impure limestone crowded with the chalky white tests of _nubecularia_: other interesting genera occur at the first named locality as _pelosina_, _hyperammina_, _haplophragmium_, _placopsilina_, _lituola_, _thurammina_, _ammodiscus_, _stacheia_, _monogenerina_, _valvulina_, _bulimina_, (?)_pleurostomella_, _lagena_, _nodosaria_, _frondicularia_, _geinitzina_, _lunucammina_, _marginulina_, _vaginulina_, _anomalina_ and _truncatulina_. the sandy matrix of certain _glossopteris_ leaf-beds in the collie coal measures in w. australia have yielded some dwarfed examples belonging to the genera _bulimina_, _endothyra_, _valvulina_, _truncatulina_ and _pulvinulina_; whilst in the irwin river district similar beds contain _nodosaria_ and _frondicularia_ (fig. ). =triassic foraminifera.--= the triassic and rhaetic clays of europe occasionally show traces of foraminiferal shells, probably of estuarine habitat, as do the wianamatta beds of new south wales, which also belong to the triassic epoch. the australian representatives are placed in the genera _nubecularia_, _haplophragmium_, _endothyra_, _discorbina_, _truncatulina_, and _pulvinulina_. these shells are diminutive even for foraminifera, and their starved condition indicates uncongenial environment. =jurassic foraminifera.--= the jurassic limestones of western australia, at geraldton, contain many species of foraminifera, principally belonging to the spirally coiled and slipper-shaped _cristellariae_. other genera present are _haplophragmium_, _textularia_, _bulimina_, _flabellina_, _marginulina_, _vaginulina_, _polymorphina_, _discorbina_, and _truncatulina_. =cretaceous foraminifera.--= in the lower cretaceous rocks known as the rolling downs formation in queensland, shells of the foraminifera are found in some abundance at wollumbilla. they are represented chiefly by _cristellaria_ and _polymorphina_. [illustration: =fig. .--structure in lepidocyclina.= a--vertical section through test of lepidocyclina marginata, michelotti sp.: showing the equatorial chambers (eq. c) and the lateral chambers (l.c.) b--section through the median disc, showing the hexagonal and ogive chambers. Ã� . cainozoic (janjukian). batesford, near geelong, victoria. (_f.c. coll._) ] =cainozoic foraminifera.--= the cainozoic strata in all parts of the world are very rich in foraminifera, and the genera, and even many species are similar to those now found living. certain types, however, had a restricted range, and are therefore useful as indicators of age. such are the nummulites and the _orbitoides_ of the eocene and the oligocene of europe, india and the west indies; and the _lepidocyclinae_ of the miocene of europe, india, japan and australia (fig. ). the genus _lepidocyclina_ is typically represented in the batesford beds near geelong, victoria by _l. tournoueri_, a fossil of the burdigalian stage (middle miocene) in europe, as well as by _l. marginata_. a limestone with large, well-preserved tests of the same genus, and belonging to a slightly lower horizon in the miocene has lately been discovered in papua. [illustration: =fig. .--cainozoic foraminifera.= a--miliolina vulgaris, d'orb. sp. oligocene-recent. vict. and s.a. b--textularia gibbosa, d'orb. oligocene and miocene. vict. & s.a. c--nodosaria affinis, d'orb. oligocene. victoria. d--polymorphina elegantissima. p. and j. oligocene-recent. vict. and s.a. e--truncatulina ungeriana, d'orb. sp. oligocene-recent. vict. & s.a. f--amphistegina vulgaris, d'orb. oligocene-l. pliocene. vict. & s.a. ] some of the commoner foraminifera found in the cainozoic beds of southern australia are--_miliolina vulgaris_, _textularia gibbosa_, _nodosaria affinis_, _polymorphina elegantissima_, _truncatulina ungeriana_ and _amphistegina lessonii_ (fig. ). the first-named has a chalky or porcellanous shell; the second a sandy test; the third and fourth glassy or hyaline shells with excessively fine tubules; the fifth a glassy shell with numerous surface punctations due to coarser tubules than usual in the shell-walls; whilst the last-named has a smooth, lenticular shell, also hyaline, and occurring in such abundance as often to constitute a foraminiferal rock in itself. =pleistocene foraminifera.--= the estuarine deposits of pleistocene age in southern australia often contain innumerable shells of _miliolina_, _rotalia_ and _polystomella_. one thin seam of sandy clay struck by the bores in the victorian mallee consists almost entirely of the shells of the shallow-water and estuarine species, _rotalia beccarii_. * * * * * =radiolaria: their structure.--= the organisms belonging to the order _radiolaria_ are microscopic, and they are all of marine habitat. the body of a radiolarian consists of a central mass of protoplasm enclosed in a membranous capsule, and contains the nuclei, vacuoles, granules and fat globules; whilst outside is a jelly-like portion which throws off pseudopodia or thin radiating threads. the skeleton of radiolaria is either chitinous or composed of clear, glassy silica, and is often of exquisitely ornamental and regular form. =habitat.--= these tiny organisms generally live in the open ocean at various depths, and sinking to the bottom, sometimes as deep as , to , fathoms, they form an ooze or mud. =subdivisions.--= radiolaria are divided into the four legions or orders,--acantharia, spumellaria, nasselaria and phaeodaria: only the second and third groups are found fossil. the spumellarians are spherical, ellipsoidal, or disc-shaped, and the nasselarians conical or helmet-shaped. =cambrian radiolaria.--= certain cherts or hard, siliceous rocks of the palaeozoic era are often crowded with the remains of radiolaria, giving the rock a spotted appearance. (see _antea_, fig. ). some of the genera thus found are identical with those living at the present day, whilst others are peculiar to those old sediments. in australia, remains of their siliceous shells have been found in cherts of lower cambrian age near adelaide. these have been provisionally referred to the genera _carposphaera_ and _cenellipsis_ (fig. ). =ordovician radiolaria.--= radiolaria have been detected in the lower ordovician rocks of victoria, in beds associated with the graptolite slates of this series. in new south wales radiolarian remains are found in the cherts and slates of upper ordovician age at cooma and mandurama. =silurian radiolaria.--= the silurian black cherts of the jenolan caves in new south wales contain casts of radiolaria. =devonian radiolaria.--= the lower devonian red jaspers of bingera and barraba in new south wales have afforded some casts of radiolaria, resembling _carposphaera_ and _cenosphaera_. [illustration: =fig. .--fossil radiolaria.= a--aff. carposphaera (after david and howchin). cambrian. brighton, s.a. b--cenosphaera affinis, hinde. mid. devonian. tamworth, n.s.w. c--amphibrachium truncatum, hinde. up. cretaceous. pt. darwin. d--dictyomitra triangularis, hinde. up. cretaceous. pt. darwin. ] the large number of fifty-three species have been found in the radiolarian rocks of middle devonian age at tamworth in new south wales (fig. ). these have been referred to twenty-nine genera comprising amongst others, _cenosphaera_, _xiphosphaera_, _staurolonche_, _heliosphaera_, _acanthosphaera_ and _spongodiscus_. =cretaceous radiolaria.--= although certain silicified rocks in the jurassic in europe have furnished a large series of radiolaria, the australian marine limestones of this age have not yielded any of their remains up to the present. they have been found, however, in the lower cretaceous of queensland, and in the (?)upper cretaceous of port darwin, n. australia. the radiolaria from the latter locality belong to the sub-orders prunoidea, discoidea and cyrtoidea (fig. ). the rock which contains these minute fossils is stated to be eaten by the natives for medicinal purposes. as its composition is almost pure silica, its efficacy in such cases must be more imaginary than real. =cainozoic radiolaria.--= cainozoic rocks of pliocene age, composed entirely of radiolaria, occur at barbados in the west indies. no cainozoic radiolaria, however, have been found either in australia or new zealand up to the present time. * * * * * common or characteristic fossils of the foregoing chapter. foraminifera. _nubecularia stephensi_, howchin. carbopermian: tasmania and new south wales. _frondicularia woodwardi_, howchin. carbopermian: w. australia and new south wales. _geinitzina triangularis_, chapm. & howchin. carbopermian: new south wales. _pulvinulina insignis_, chapman. trias (wianamatta series): new south wales. _marginulina solida_, terquem. jurassic: w. australia. _flabellina dilatata_, wisniowski. jurassic: w. australia. _vaginulina striata_, d'orbigny. lower cretaceous: queensland. _truncatulina lobatula_, w. and j. sp. lower cretaceous: queensland. _miliolina vulgaris_, d'orb. sp. cainozoic: victoria and s. australia. _textularia gibbosa_, d'orb. cainozoic: victoria and s. australia. _nodosaria affinis_, d'orb. cainozoic: victoria and s. australia. _polymorphina elegantissima_, parker and jones. cainozoic: victoria, tasmania, and s. australia. _truncatulina ungeriana_, d'orb. sp. cainozoic: victoria, king island, and s. australia. _amphistegina lessonii_, d'orb. cainozoic: victoria and s. australia. _lepidocyclina martini_, schlumberger. cainozoic (balcombian and janjukian): victoria. _l. tournoueri_, lemoine and douvillé. cainozoic (junjukian): victoria. _cycloclypeus pustulosus_, chapman. cainozoic (janjukian): victoria. _fabularia howchini_, schlumberger. cainozoic (kalimnan): victoria. _hauerina intermedia_, howchin. cainozoic (kalimnan): victoria. _rotalia beccarii_, linné sp. pleistocene: victoria and s. australia. _polystomella striatopunctata_, fichtel and moll sp. pleistocene: victoria and s. australia. radiolaria. (?) _carposphaera_ sp. lower cambrian: south australia. (?) _cenellipsis_ sp. lower cambrian: south australia. _cenosphaera affinis_, hinde. devonian: new south wales. _staurolonche davidi_, hinde. devonian: new south wales. _amphibrachium truncatum_, hinde. upper cretaceous: northern territory. _dictyomitra triangularis_, hinde. upper cretaceous: northern territory. * * * * * literature. foraminifera. carbopermian.--howchin, w. trans. roy. soc. s. austr., vol. xix. ; pp. - . chapman, f. and howchin, w. mem. geol. surv. new south wales, pal. no. , . chapman, f. bull. geol. surv. w. austr., no. , , pp. - . trias.--chapman, f. rec. geol. surv. new south wales, vol. viii. pt. , , pp. - . jurassic.--chapman, f. proc. roy. soc. vict., vol. xvi. (n.s.), pt. ii., , pp. - . cretaceous.--moore, c. quart. journ. geol. soc., vol. xxvi. , pp. and . howchin, w. trans. roy. soc. s. austr., vol. viii. , pp. - . idem, ibid., vol. xix., , pp. - . idem, bull. geol. surv. w. austr., no. , , pp. - . cainozoic.--howchin, w. trans. roy. soc. s. austr., vol. xii. , pp. - . idem, ibid., vol. xiv. , pp. - . jensen, h. i. proc. linn. soc. new south wales, vol. xxix. pt. , , pp. - . goddard, e. j. and jensen, h. i. ibid., vol. xxxii. pt. , , pp. - . chapman, f. journ. linn. soc. lond. zool., vol. xxx. , pp. - . general.--howchin, w. rep. austr. assoc. adv. sci., adelaide meeting, , pp. - . radiolaria. lower cambrian.--david, t. w. e. and howchin, w. proc. linn. soc. new south wales, vol. xxi. , p. . devonian.--david, t. w. e. proc. linn. soc. new south wales, vol. xxi. , pp. - . hinde, g. j. quart. journ. geol. soc., vol. lv. , pp. - . upper cretaceous.--hinde, g. j. quart. journ. geol. soc., vol. xlix. , pp. - . chapter vii. fossil sponges, corals and graptolites. _sponges._ =characteristics of sponges.--= the sponges are sometimes placed by themselves as a separate phylum, the porifera. with the exception of a few freshwater genera, they are of marine habit and to be found at all depths between low tide (littoral) and deep water (abyssal). sponges are either fixed or lie loosely on the sea-floor. they possess no organs of locomotion, and have no distinct axis or lateral appendages. they exist by setting up currents in the water whereby the latter is circulated through the system, carrying with it numerous food particles, their tissues being at the same time oxygenated. their framework, in the siliceous and calcareous sponges, is strengthened by a mineral skeleton, wholly or partially capable of preservation as a fossil. =cambrian and ordovician sponges.--= the oldest rocks in australia containing the remains of sponges are the cambrian limestones of south australia, at ardrossan and elsewhere. some of these sponge-remains are referred to the genus _protospongia_, a member of the hexactinellid group having -rayed skeletal elements. when complete, the _protospongia_ has a cup- or funnel-shaped body, composed of large and small modified spicules, which form quadrate areas, often seen in isolated or aggregated patches on the weathered surface of the rock. _protospongia_ also occurs in the lower ordovician slates and shales of lancefield (_p. oblonga_), and bendigo (_p. reticulata_ and _p. cruciformis_), in victoria (fig. a). at st. david's, in south wales, the genus is found in rocks of middle cambrian age. the south australian limestones in which _protospongia_ occurs are usually placed in the lower cambrian. [illustration: =fig. .--palaeozoic sponges, &c.= a--protospongia reticulata, t. s. hall. low. ordovician. bendigo. b--receptaculites fergusoni, chapm. silurian. wombat creek, vict. c--r. australis, salter. (section of wall, etched, after eth. & dun) mid. devonian. co. murray, n.s.w. d--protopharetra scoulari, eth. fil. cambrian. s.a. ] another genus of sponges, _hyalostelia_, whose affinities are not very clear, occurs in the south australian cambrian at curramulka. this type is represented by the long, slightly bent, rod-like spicules of the root-tuft, and the skeletal spicules with six rays, one of which is much elongated. _stephanella maccoyi_ is a monactinellid sponge, found in the lower ordovician (bendigo series) of bendigo, victoria. =silurian sponges.--= numerous sponges of silurian age are found in the neighbourhood of yass, new south wales, which belong to the lithistid group, having irregular, knotty and branching spicules. these sponges resemble certain fossil fruits, generally like diminutive melons; their peculiar spicular structure, however, is usually visible on the outside of the fossil, especially in weathered specimens. the commonest genus is _carpospongia_. =receptaculites: silurian to carboniferous.--= in upper silurian, devonian, and carboniferous times the curious saucer- or funnel-shaped bodies known as _receptaculites_ must have been fairly abundant in australia, judging by their frequent occurrence as fossils. they are found as impressions or moulds and casts in some of the mudstones and limestones of silurian age in victoria, as at loyola and wombat creek, in west and north-east gippsland respectively. in the devonian limestones of new south wales they occur at fernbrook, near mudgee, at the goodradigbee river, and at cavan, near yass; also in beds of the same age in victoria, at bindi, and buchan (fig. , b.c.). _receptaculites_ also occur in the star beds of upper devonian or lower carboniferous age in queensland, at mount wyatt. it will thus be seen that this genus has an extensive geological range. =carbopermian sponges.--= a monactinellid sponge, provisionally referred to _lasiocladia_, has been described from the gympie beds of the rockhampton district, queensland. _lasiocladia_, as well as the hexactinellid sponge _hyalostelia_, occurs in the carbopermian of new south wales. =cretaceous sponges.--= no sponge-remains seem to occur above the carbopermian in australia until we reach the cretaceous rocks. in the lower cretaceous series in queensland a doubtful member of the hexactinellid group is found, namely, _purisiphonia clarkei_. in the upper cretaceous of the darling downs district pyritized sponges occur which have been referred to the genus _siphonia_, a member of the lithistid group, well known in the cretaceous of europe. =cainozoic sponges.--= a white siliceous clay, supposed to be from a "deep lead," in the norseman district in western australia, has proved to consist almost entirely of siliceous sponge-spicules, belonging to the monactinellid, the tetractinellid, the lithistid, and the hexactinellid groups (fig. a, b). the reference of the deposit to a "deep lead" or alluvial deposit presents a difficulty, since these sponge-spicules represent moderately deep water marine forms. this deposit resembles in some respects the spicule-bearing rock of oamaru, new zealand, which is of miocene age. [illustration: =fig. .--cainozoic sponges.= a--latrunculia sp. (after hinde). cainozoic. deep lead, norseman, w.a. b--geodia sp. (after hinde). cainozoic. deep lead, norseman, w.a. c--ecionema newberyi. mccoy sp. cainozoic. boggy creek, gippsland, vict. d--plectroninia halli, hinde. cainozoic (janjukian). moorabool, vict. e--tretocalia pezica, hinde. cainozoic. flinders, vict. ] [illustration: =fig. .--silurian corals.= a--cyathophyllum approximans, chapm. silurian (yer.). gippsland, vict. b--favosites grandipora, eth. fil. silurian (yer.). lilydale, vict. c--favosites grandipora, vertical section. ditto. d--f. grandipora, transverse section. ditto. e--pleurodictyum megastomum, dun. lilydale, vict. f--halysites peristephesicus, eth. fil. silurian. n.s. wales. g--heliolites interstincta, wahl sp vict. (transv. sect). silurian.. ] in the cainozoic beds of southern australia sponges with calcareous skeletons are not at all uncommon. the majority of these belong to the lithonine section of the calcispongiae, in which the spicules are regular, and not fixed together. living examples of these sponges, closely related to the fossils, have been dredged from the japanese sea. the fossils are found mainly in the janjukian, at curlewis, in the moorabool river limestones, and in the polyzoal rock of flinders, all in victoria. they belong to the genera _bactronella_, _plectroninia_ and _tretocalia_ (fig. , d and e). some diminutive forms also occur in the older series, the balcombian, at mornington, namely, _bactronella parvula_. at boggy creek, near sale, in victoria, a tetractinellid sponge, _ecionema newberyi_, is found in the janjukian marls; spicules of this form have also been noted from the clays of the altona bay coal-shaft (fig. c). * * * * * the _archaeocyathinae_: an ancient class of organisms related both to the sponges and the corals. =archaeocyathinae in cambrian strata.--= these curious remains have been lately made the subject of detailed research, and it is now concluded that they form a group probably ancestral both to the sponges and the corals. they are calcareous, and generally cup-shaped or conical, often furnished at the pointed base with roots or strands for attachment to the surrounding reef. they have two walls, both the inner and the outer being perforated like sponges. as in the corals, they are divided by transverse septa and these are also perforated. certain of the genera as _protopharetra_ (fig. d), _coscinocyathus_, and _archaeocyathina_, are common to the cambrian of sardinia and south australia, whilst other genera of the class are also found in siberia, china, canada and the united states. a species of _protopharetra_ was recently detected in a pebble derived from the cambrian limestone in the antarctic, as far south as deg. an _archaeocyathina_ limestone has also been found in situ from shackleton's farthest south. _corals_ (class anthozoa). =rugose corals.--= many of the older types of corals from the palaeozoic rocks belong to the tetracoralla (septa in multiples of four), or rugosa (i.e., with wrinkled exterior). =ordovician corals.--= in great britain and north america rugose corals are found as early as ordovician times, represented by _streptelasma_, _petraia_, etc. in australia they seem to first make their appearance in the silurian period. =silurian corals.--= in rocks of silurian age in australia we find genera like _cyathophyllum_ (with single cups or compound coralla), _diphyphyllum_, _tryplasma_ and _rhizophyllum_, the first-named often being very abundant. the compound corallum of _cyathophyllum approximans_ presents a very handsome appearance when cut transversely and polished. this coral is found in the newer silurian limestone in victoria; it shows an alliance with _c. mitchelli_ of the middle devonian of the murrumbidgee river, new south wales (fig. a). =silurian hexacoralla.--= it is, however, to the next group, the hexacoralla, with septa in multiples of six, twelve, and twenty-four, that we turn for the most varied and abundant types of corals in silurian times. the genus _favosites_ (honey-comb coral) is extremely abundant in australian limestones (fig. b, c), such as those of lilydale, walhalla, and waratah bay in victoria, and of hatton's corner and other localities near yass, in new south wales. _pleurodictyum_ is also a familiar type in the australian silurian, being one of the commonest corals in the yeringian stage; although, strange to say, in germany and n. america, it is typical of devonian strata (fig. e). _pleurodictyum_ had a curious habit of growing, barnacle fashion, on the side of the column of the crinoids or sea-lilies which flourished in those times. _syringopora_, with its funnel-shaped tabulae or floor partitions, is typical of many australian limestones, as those from lilydale, victoria, and the delegate river, new south wales. _halysites_ (chain coral), with its neat strings of tubular and tabulated corallites joined together by their edges, is another striking coral of the silurian period (fig. f). this and the earlier mentioned _syringopora_, is by some authors regarded as belonging to the alcyonarian corals (typically with eight tentacles). _halysites_ is known from the limestones of the mitta mitta river, n.e. gippsland, victoria; from the molong and canobolas districts in new south wales; from the gordon river limestone in tasmania; and from chillagoe in queensland. abroad it is a well known type of coral in the wenlockian of gotland in scandinavia, and shropshire in england, as well as in the niagara limestone of the united states. =silurian octocoralla.--= perhaps the most important of the octocoralla is _heliolites_ ("sunstone"), which is closely allied to the blue coral, _heliopora_, a frequent constituent of our modern coral reefs. the genus _heliolites_ has a massive, calcareous corallum, bearing two kinds of pores or tubes, large (autopores) containing complete polyps, and small (siphonopores) containing the coenosarc or flesh of the colony. both kinds of tubes are closely divided by tabulae, whilst the former are septate. _heliolites_ is of frequent occurrence in the silurian limestones of new south wales and victoria (fig. g). =devonian corals.--= the middle devonian beds of australia are chiefly limestones, such as the buchan limestone, victoria; the burdekin series, queensland; and the tamworth limestone of new south wales. these rocks, as a rule, are very fossiliferous, and the chief constituent fossils are the rugose and perforate corals. _campophyllum gregorii_ is a common form in the buchan limestone (fig. a), as well as some large mushroom-shaped _favosites_, as _f. gothlandica_ and _f. multitabulata_. other genera which may be mentioned as common to the australian middle devonian rocks are, _cyathophyllum_, _sanidophyllum_ and _spongophyllum_, _heliolites_ is also found in limestones of this age in new south wales and queensland. [illustration: =fig. .--upper palaeozic corals.= a--campophyllum gregorii, eth. fil. mid. devonian. buchan, vict. b--pachypora meridionalis, nich. & eth. fil. mid devonian. queens. c--aulopora repens, kn. & w. (after hinde). devonian. kimberley district, w.a. d--zaphrentis culleni, eth. fil. carboniferous. new south wales. e--trachypora wilkinsoni, eth. fil. carbopermian (up. marine ser.) new south wales. f--stenopora crinita, lonsdale. carbopermian (up. mar. ser.) n.s.w. ] in the burdekin series (middle devonian) in queensland we also find _cystiphyllum_, _favosites gothlandica_, and _pachypora meridionalis_ (fig. b), whilst in beds of the same age at rough range in western australia are found _aulopora repens_ (fig. c), and another species of _pachypora_, namely, _p. tumida_. =carbopermian corals.--= the only true carboniferous marine fauna occurring in australia, appears to be that of the star beds in queensland, but so far no corals have been found. the so-called carboniferous of western australia may be regarded as carbopermian or even of permian age. the marine carbopermian beds of new south wales contain several genera of corals belonging to the group rugosa, as _zaphrentis_ (fig. d), _lophophyllum_, and _campophyllum_. of the tabulate corals may be mentioned _trachypora wilkinsoni_, very typical of the upper marine series (fig. e) and _cladochonus_. in the gympie beds of the same system in queensland occur the following rugose corals, _zaphrentis profunda_ and a species of _cyathophyllum_. in the carbopermian of western australia the rugose corals are represented by _amplexus_, _cyathophyllum_, and _plerophyllum_, which occur in rocks on the gascoyne river. the imperfectly understood group of the monticuliporoids, by some authors placed with the polyzoa (order trepostomata), are well represented in australia by the genus _stenopora_ (fig. f). the corallum is a massive colony of long tubes set side by side and turned outwards, the polyp moving upwards in growth and cutting off the lower part of the tube by platforms like those in the tabulate corals. some of the species of _stenopora_, like _s. tasmaniensis_, of new south wales and tasmania, are found alike in the lower and upper marine series. _s. australis_ is confined to the bowen river coal-field of queensland. _stenopora_ often attains a large size, the corallum reaching over a foot in length. neither jurassic or cretaceous corals have been found in australasia, although elsewhere as in europe and india, the representatives of modern corals are found in some abundance. =cainozoic corals.--= in tertiary times the marine areas of southern australia were the home of many typical solitary corals of the group of the hexacoralla. in the balcombian beds of mornington, victoria, for instance, we have genera such as _flabellum_, _placotrochus_, _sphenotrochus_, _ceratotrochus_, _conosmilia_, _trematotrochus_, _notophyllia_ and _balanophyllia_ (fig. ). [illustration: =fig. .--cainozoic corals.= a--flabellum victoriae, duncan. balcombian. mornington, vict. b--placotrochus deltoideus, dunc. balcombian. muddy creek, hamilton, vic. c--balanophyllia seminuda, dunc. balcombian. muddy creek, hamilton, vic. d--stephanotrochus tatei, dennant. janjukian. torquay, near geelong, vict. e--thamnastraea sera, duncan. janjukian. table cape, tas. f--graphularia senescens. tate sp. janjukian. waurn ponds, near geelong, vic. g--trematotrochus clarkii, dennant. kalimnan. gippsland lakes, vic. ] corals especially characteristic of the janjukian series are _paracyathus tasmanicus_, _stephanotrochus tatei_, _montlivaltia variformis_, _thamnastraea sera_ and _dendrophyllia epithecata_. the stony axis of the sea-pen, _graphularia senescens_, a member of the octocoralla, is also typical of this stage, and are called "square-bones" by the quarrymen at waurn ponds, near geelong, where these fossils occur. the kalimnan corals are not so abundantly represented as in the foregoing stages, but certain species of _flabellum_ and _trematotrochus_, as _f. curtum_ and _t. clarkii_, are peculiar to those beds. several of the janjukian corals persist into kalimnan times, some dating as far back as the balcombian, as _sphenotrochus emarciatus_. the sea-pen, _graphularia senescens_ is again found at this higher horizon, at beaumaris; it probably represents a varietal form, the axis being smaller and more slender. other examples of the octocoralla are seen in _mopsea_, two species of which are found in the janjukian at cape otway; the deeper beds of the mallee; and the mount gambier series. a species of the astraeidae (star-corals) of the reef-forming section, _plesiastraea st.vincenti_, is found in the kalimnan of hallett's cove, south australia. _hydrozoa._ the few animals of this group met with in fossil faunas are represented by the living _millepora_ (abundant as a coral reef organism), _hydractinia_ (parasitic on shells, etc.), and _sertularia_ (sea-firs). =milleporids and stylasterids.--= although so abundant at the present time, the genus _millepora_ does not date back beyond the pleistocene. the eocene genus _axopora_ is supposed to belong here, but is not australian. of the stylasterids one example is seen in _deontopora_, represented by the branchlets of _d. mooraboolensis_, from the janjukian limestone of the moorabool valley, near geelong. =hydractinia.--= _hydractinia_ dates from the upper cretaceous rocks in england, and in australia its encrusting polypidom is found attached to shells in the polyzoal limestone of mount gambier (miocene). stromatoporoids. an important group of reef-builders in palaeozoic times was the organism known as _stromatopora_, and its allies. the structures of these hydroid polyps resemble successional and repetitional stages of a form like _hydractinia_. as in that genus it always commenced to grow upon a base of attachment such as a shell, increasing by successive layers, until the organic colony often reached an enormous size, and formed great mounds and reefs (see _antea_, fig. ). the stromatoporoid structure was formed by a layer of polyp cells separated by vertical partitions, upon which layer after layer was added until a great vertical thickness was attained. this limestone-making group first appeared in the silurian, and probably reached its maximum development in middle devonian times, when it almost disappeared, except to be represented in carbopermian strata by a few diminutive forms. [illustration: =fig. .--stromatoporoidea and cladophora.= a--actinostroma clathratum, nich. devonian. rough range, w.a. b--actinostroma clathratum, nich. devonian. rough range, w.a. vertical section. (_after g. j. hinde_). c--callograptus sp. up. ordovician. san remo, vict. (_after t. s. hall_). d--ptilograptus sp. up. ordovician. san remo, vict. (_after t. s. hall_). e--dictyonema pulchellum, t. s. hall. l. ordov. lancefield, vict. f--dictyonema macgillivrayi, t. s. hall. l. ordov. lancefield, vict. ] =silurian stromatoporoids.--= in the silurian limestones of victoria (lilydale, waratah bay, walhalla and loyola), and new south wales (near yass), stromatoporoids belonging to the genera _clathrodictyon_ (probably _c. regulare_), _stromatopora_ and _idiostroma_ occur. _stromatoporella_ has been recorded from the silurian rocks of the jenolan caves, new south wales. =devonian stromatoporids.--= the middle devonian strata of bindi, victoria, yield large, massive examples of _actinostroma_. this genus is distinguished from the closely allied _clathrodictyon_ by its vertical pillars passing through several laminae in succession. rocks of the same age in queensland contain _stromatopora_, whilst in western australia the rough range limestone has been shown to contain _actinostroma clathratum_ (fig. a, b) and _stromatoporella eifeliensis_. cladophora. =palaeozoic cladophora.--= some branching and dendroid forms of hydrozoa probably related to the modern calyptoblastea ("covered buds"), such as _sertularia_ and _campanularia_, are included in the cladophora ("branch bearers"). they existed from cambrian to devonian times, and consist of slender, forking branches sometimes connected by transverse processes or dissepiments, the branches bearing on one or both sides little cups or hydrothecae which evidently contained the polyps, and others of modified form, perhaps for the purpose of reproduction. the outer layer, called the periderm was of chitinous material. they were probably attached to the sea-floor like the sertularians (sea-firs). =dictyonema and allies.--= remains of the above group are represented in the australian rocks by several species of _dictyonema_ (fig. e, f) occurring in the lower ordovician of lancefield, and in similar or older shales near mansfield. some of these species are of large size, _d. grande_ measuring nearly a foot in width. the genera _callograptus_, _ptilograptus_ (fig. c, d) and _dendrograptus_ are also sparsely represented in the upper ordovician of victoria, the two former from san remo, the latter from bulla. graptolites (graptolitoidea).-- =value of graptolites to stratigraphist.--= the graptolites were so named by linnaeus from their resemblances to writing on the slates in which their compressed remains are found. they form a very important group of palaeozoic fossils in all parts of the world where these rocks occur, and are well represented in australasia. the species of the various graptolite genera are often restricted to particular beds, and hence they are of great value as indicators of certain horizons or layers in the black, grey or variously coloured slates and shales of lower ordovician to silurian times. by their aid a stratum or set of strata can be traced across country for long distances, and the typical species can be correlated even with those in the older slates and shales of great britain and north america. =nature of graptolites.--= the graptolites were compound animals, consisting of a number of polyps inserted in cups or thecae which budded out in a line from the primary sicula or conical chamber, which chamber was probably attached to floating sea-weed, either by a fine thread (nema), or a disc-like expansion. this budding of the polyp-bearing thecae gives to the polypary or colony the appearance of a fret-saw, with the teeth directed away from the sicula. the habit of the earlier graptolites was to branch repeatedly, as in _clonograptus_, or to show a compound leaf-like structure as in _phyllograptus_. later on the many-branched forms had their branches reduced until, as in _didymograptus_, there were only two branches. sometimes the branches opened out to direct the thecae upwards, the better to procure their food supply. in _diplograptus_ the thecae turned upwards and acquired a support by the formation of a medium rod (virgula), often ending in a disc or float. in silurian times _monograptus_ prevailed, a genus having only a single row of thecae supported by a straight or curved virgula. in _retiolites_ the polypary opened out by means of a net-work of fine strands, rendering it better able to float, at the same time retaining its original strength. =lower ordovician graptolites, victoria.--= the lower ordovician slates and shales of victoria have been successfully divided into several distinct series by means of the graptolites. these, commencing at the oldest, are:-- ( ) lancefield series. characterised by _bryograptus clarki_, _b. victoriae_, _didymograptus pritchardi_, _d. taylori_ and _tetragraptus decipiens_. other forms less restricted are, _clonograptus magnificus_ (measuring over a yard in breadth), _c. flexilis_, _c. rigidus_, _leptograptus antiquus_ and _tetragraptus approximatus_ (fig. ). ( ) bendigo series. characterised by _tetragraptus fruticosus_, _t. pendens_, _trichograptus fergusoni_ and _goniograptus thureaui_. this series also contains _tetragraptus serra_ (ranging into darriwill series), _t. bryonoides_, _t. quadribrachiatus_, _t. approximatus_ (base of the series), _phyllograptus typus_, _dichograptus octobrachiatus_, _goniograptus macer_ and many _didymograpti_, including _d. bifidus_ (fig. ). [illustration: =fig. .--lower ordovician graptolites.= a--bryograptus clarki, t. s. hall. l. ordovician. lancefield, vict. b--tetragraptus fruticosus, j. hall sp. l. ordovician. lancefield. c--phyllograptus typus, j. hall. l. ordovician. lancefield. d--goniograptus macer, t. s. hall. l. ordovician. lancefield. e--didymograptus caduceus, salter. l. ordovician. lancefield. f--trigonograptus wilkinsoni, t. s. hall. l. ordov. darriwill, vict. ] [illustration: =fig. .--lower ordovician graptolites.= a--loganograptus logani, j. hall sp. l. ordov. newham, vict. b--tetragraptus approximatus, nich. l. ordovician. canada and victoria. (_after nicholson_) c--tetragraptus serra, brongn. sp. l. ordovician. lancefield, vict. d--didymograptus bifidus, j. hall. l. ordovician. guildford, vict. ] ( ) castlemaine series. characterised by _didymograptus bifidus_, _d. caduceus_ and _loganograptus logani_. _phyllograptus_ persists from the bendigo series. it also contains _tetragraptus serra_, _t. bryonoides_, _t. quadribrachiatus_, _goniograptus macer_ and several _didymograpti_. ( ) darriwill series. characterised by _trigonograptus wilkinsoni_. also contain _diplograptus_, _glossograptus_ and _lasiograptus_, whilst _didymograptus_ is rare. =lower ordovician graptolites, new zealand.--= in new zealand lower ordovician graptolites are found in the kakanui series, at nelson, north-west of south island. some of the commoner forms are _didymograptus extensus_, _d. caduceus_, _loganograptus logani_, _phyllograptus typus_, _tetragraptus similis_ and _t. quadribrachiatus_. graptolites agreeing closely with those of the lancefield series of victoria occur near preservation inlet in the extreme south-west, and have been identified as _clonograptus rigidus_, _bryograptus victoriae_ and _tetragraptus decipiens_. =upper ordovician graptolites, victoria.--= the upper ordovician rocks of victoria, as at wombat creek and mount wellington in gippsland, and at diggers' rest near sunbury, contain the double branched forms like _dicranograptus ramosus_, _dicellograptus elegans_ and _d. sextans_; the sigmoidal form _stephanograptus gracilis_; and the diprionidian (biserial) forms as _diplograptus tardus_, _climacograptus bicornis_, _cryptograptus tricornis_, _glossograptus hermani_ and _lasiograptus margaritatus_ (fig. ). [illustration: =fig. .--upper ordovician and silurian graptolites.= a--dicranograptus ramosus, j. hall sp. up. ordovician. victoria. b--dicellograptus elegans, carruthers sp. up. ordovician. victoria. c--diplograptus carnei, t. s. hall. up. ordovician. n. s. wales. d--climacograptus bicornis, j. hall. up. ordovician. victoria. e--glossograptus hermani, t. s. hall. up. ordovician. victoria. f--retiolites australis, mccoy. silurian. keilor, victoria. g--monograptus dubius, suess. silurian. wood's point, victoria. ] =upper ordovician graptolites, new south wales.--= in new south wales, at tallong, the upper ordovician graptolites are well represented by such forms as _dicellograptus elegans_, _dicranograptus nicholsoni_, _diplograptus carnei_, _d. foliaceus_, _cryptograptus tricornis_ and _glossograptus quadrimucronatus_, etc. other localities in new south wales for this graptolite fauna are stockyard creek, currowang, tingaringi, lawson, and mandurama. =tasmania.--= from tasmania a _diplograptus_ has been recorded, but the particular horizon and locality are uncertain. =silurian graptolites, victoria.--= in the silurian shales at keilor, in victoria, _monograptus_ is a common genus, and _cyrtograptus_ and _retiolites australis_ (fig. f) also occur. several species of _monograptus_ have also been found at south yarra and studley park. at the latter place and walhalla _monograptus dubius_, which is a wenlock and ludlow fossil in britain, has been found in some abundance (fig. g). * * * * * common or characteristic fossils of the foregoing chapter. sponges. _protospongia_ sp. cambrian: s. australia. _hyalostelia_ sp. cambrian: s. australia. _protospongia oblonga_, hall. l. ordovician: victoria. _stephanella maccoyi_, hall. l. ordovician: victoria. _carpospongia_ sp. silurian: yass, new south wales. _receptaculites fergusoni_, chapman. silurian: victoria. _receptaculites australis_, salter sp. devonian: victoria and new south wales. carboniferous: queensland. (?) _lasiocladia hindei_, eth. fil. carbopermian: queensland. _purisiphonia clarkei_, bowerbank. lower cretaceous: queensland. _geodia_ sp. cainozoic: w. australia. _tethya_ sp. cainozoic: w. australia. _ecionema newberyi_, mccoy sp. cainozoic: victoria. _plectroninia halli_, hinde. cainozoic (janjukian): victoria. _tretocalia pezica_, hinde. cainozoic (janjukian): victoria. archaeocyathinae. _protopharetra scoulari_, etheridge, fil. cambrian: s. australia. _coscinocyathus australis_, taylor. cambrian: s. australia. _archaeocyathina ajax_, taylor. cambrian: s. australia. corals. _cyathophyllum approximans_, chapman. silurian: victoria. _tryplasma liliiformis_, etheridge, fil. silurian: new south wales. _favosites grandipora_, etheridge fil. silurian: victoria. _pleurodictyum megastomum_, dun. silurian: victoria. _halysites peristephicus_, etheridge, fil. silurian: new south wales. _heliolites interstincta_, linné sp. silurian: victoria. _campophyllum gregorii_, eth. fil. middle devonian: victoria and queensland. _cystiphyllum australasicum_, eth. fil. middle devonian: new south wales and queensland. _favosites multitabulata_, eth. fil. middle devonian: victoria and new south wales. _pachypora meridionalis_, eth. fil. middle devonian: queensland. _zaphrentis culleni_, eth. fil. carboniferous: new south wales. _lophophyllum corniculum_, de koninck. carboniferous: new south wales. _zaphrentis profunda_, eth. fil. carbopermian: queensland. _campophyllum columnare_, eth. fil. carbopermian: new south wales. _trachypora wilkinsoni_, eth. fil. carbopermian: new south wales. _stenopora tasmaniensis_, lonsdale. carbopermian: tasmania and new south wales. _flabellum gambierense_, duncan. cainozoic: victoria, s. australia and tasmania. _placotrochus deltoideus_, duncan. cainozoic: victoria, s. australia and tasmania. _sphenotrochus emarciatus_, duncan. cainozoic: victoria, s. australia, and tasmania. _ceratotrochus exilis_, dennant. cainozoic: victoria. _conosmilia elegans_, duncan. cainozoic: victoria. _balanophyllia armata_, duncan. cainozoic: victoria. _thamnastraea sera_, duncan. cainozoic: victoria and tasmania. _graphularia senescens_, tate sp. cainozoic: victoria and s. australia. hydrozoa. _clathrodictyon_ (?) _regulare_, rosen sp. silurian: victoria. _actinostroma clathratum_, nicholson. devonian: w. australia. _stromatoporella eifeliensis_, nich. devonian: w. australia. _dictyonema pulchella_, t. s. hall. lower ordovician: victoria. _ptilograptus_ sp. l. ordovician: victoria. _callograptus_ sp. lower ordovician: victoria. graptolites. _bryograptus victoriae_, t. s. hall. lower ordovician (lancefield series): victoria. _tetragraptus fruticosus_, j. hall. l. ordovician (bendigo series): victoria. _didymograptus caduceus_, salter. l. ordovician (castlemaine series): victoria. also new zealand. _didymograptus bifidus_, j. hall. l. ordovician (castlemaine series): victoria. also new zealand. _trigonograptus wilkinsoni_, t. s. hall. l. ordovician (darriwill series): victoria. _dicranograptus ramosus_, j. hall sp. upper ordovician: victoria. _monograptus dubius_, suess. silurian: victoria. _retiolites australis_, mccoy. silurian: victoria. * * * * * literature. sponges. cambrian.--tate, r. trans. r. soc. s. austr., vol. xv. (n.s.), , p. . ordovician.--hall, t. s. proc. r. soc. vict., vol. i. pt. i. , pp. , (_protospongia_). idem, ibid., vol. xi. (n.s.), pt. ii. , pp. - (_protospongia and stephanella_). silurian to carboniferous.--salter, j. w. canad. org. rem. dec. i. , p. . etheridge, r. jnr. and dun, w. s. rec. geol. surv. new south wales, vol. vi. , pp. - . chapman, f. proc. r. soc. vict. vol. xviii. (n.s.), pt. , , pp. - . carbopermian.--etheridge, r. jnr., in geol. and pal. q., , p. . cretaceous.--bowerbank, j. s. proc. zool. soc. lond., , p. . etheridge, r. jnr. in geol. and pal. queensland, , pp. , (_purisiphonia_). cainozoic.--mccoy, f. prod. pal. vict., dec. v. . chapman, f. proc. r. soc. vict., vol. xx. (n.s.), pt. , , pp. - (_ecionema_). hinde, g. j. quart. journ. geol. soc., vol. lvi., , pp. - (calcisponges). idem, bull. geol. surv. w. austr., no. , , pp. - (sponge-spicules). archaeocyathinae. etheridge, r. jnr., trans. r. soc. s. austr., vol. xiii. , pp. - . taylor, t. g. mem. roy. soc. s. austr., vol. ii., pt. , (a monograph). corals. silurian.--etheridge, r. jnr. rec. geol. surv. new south wales, vol. ii. pt. , , pp. - (silurian and devonian). idem, ibid., vol. ii. pt. , , pp. - (silurian and devonian). idem, in pal. and geol. queensland, . idem, rec. austr. mus., vol. i., no. , , pp. - (_rhizophyllum_). id., ibid., vol. iii. no. , , pp. - (_columnaria_). id., prog. rep. geol. surv. vict., no. , , pp. - . idem, mem. geol. surv. new south wales, no. , pt. i., (_halysites_). id., ibid., no. , pt. , (_tryplasma_). de koninck, l. g. ibid., pal. no. , . shearsby, a. j. geol. mag., dec. v., vol. iii. , pp. - . chapman, f. rec. geol. surv. vict., vol. ii. pt. , , pp. - . devonian.--etheridge, r. jnr. and foord, a. h. ann. mag. nat. hist., ser. v., vol. xiv., , pp. - (_alveolites_ and _amplexopora_ = _litophyllum_). etheridge, r. jnr., in geol. and pal. queensland, . idem, proc. linn. soc. new south wales, vol. ix. , pp. - . id., rec. geol. surv. new south wales, vol. vi. pt. , , pp. - (tamworth district). id., rec. austr. mus., vol. iv. no. , , pp. - . de koninck, l. g. mem. geol. surv. new south wales, pal. no. , . chapman, f. rec. geol. surv. vict., vol. iii, pt. , , pp. - . carbopermian.--etheridge, r. jnr. mem. geol. surv. new south wales, pal. no. , . idem, in geol. and pal. queensland, . id., bull. geol. surv., w. austr., no. , , pp. - . cainozoic.--duncan, p. m. quart. journ. geol. soc., vol. xxvi. , pp. - ; vol. xxxi. , pp. - ; vol. xxxii. , pp. - . woods, t. proc. linn. soc. new south wales, vol. xi., , pp. - ; ibid., vol. xxx. , pp. - . idem, trans. roy. soc. s. austr., vol. i., , pp. - . dennant, j. trans. r. soc. s. austr., vols. xxiii. ( ) to xxviii. ( ). stromatoporoids. hinde, g. j. geol. mag., dec. iii. vol. vii, , p. . graptolites. mccoy, f. prod. pal. vict., decades i. ( ): ii. ( ): v. ( ). hall, t. s. proc. roy. soc. vict., vol. iv. p. i. , pp. , (_dictyonema_). idem, geol. mag. dec. iv. vol. vi. , pp. - ; id., rep. austr. assoc. adv. sci., brisbane, , pp. - . id., rec. geol. surv. vict., vol. i. pt. , , pp. - . id., ibid., vol. iii. pt. , , pp. - . idem, rec. geol. surv. new south wales, vol. vii. part , , pp. , . ibid., pp. - . chapter viii. fossil sea-lilies, starfishes, brittle-stars and sea-urchins. =divisions of echinodermata.--= the sub-kingdom of echinodermata includes the above groups comprised in the classes crinoidea, asteroidea, ophiuroidea and echinoidea. besides these are the less important classes of the cystidea or sac-shaped echinoderms (of which no definite remains are recorded from australian rocks); the blastoidea or bud-shaped echinoderms (of which four genera are known from australia); the edrioasteroidea or sessile starfishes (unknown in australia); and the holothuroidea or sea-cucumbers (represented as fossils by the skin spicules and plates, an example of which has been recorded from australia). _crinoidea, or sea-lilies._ =crinoidea, their general structure.--= these often beautiful and graceful animals resemble a starfish mounted on a stalk. they are composed of calcareous joints and plates, and are therefore important as rock-formers. the stalk or column may be either short or long, and is generally rooted, in the adult stage, in the mud of the sea-floor. fossil crinoids were sometimes furnished with a coiled termination, which could be entwined around such objects as the stems of sea-weeds. the crinoid column is composed of numerous plates, and is round or pentagonal. upon this is fixed the calyx or cup, with its attached arms, which serve to bring food to the mouth, situated on the upper part of the cup. the arms are grooved, and the water, being charged with food particles (animalcula), pours down these channels into the mouth. the stem elevates the animal above the mud or silt of the sea-floor, thus making it more easy for it to obtain its food supply. the stalks of fossil crinoids sometimes reached the enormous length of feet. their calcareous skeleton is built upon a plan having five planes of symmetry; this pentamerism is found throughout the crinoids, the blastoids and the free-moving echinoderma. crinoids range from moderately shallow- to deep-water, and at the present day are almost restricted to abyssal conditions. the more ancient types usually found their habitats amongst reefs or in comparatively clear water, where there was a marked freedom from sediment, although that was not an essential, as seen by their numerous remains in the australian mudstones and sandstones. =cambrian crinoids.--= the group of the crinoidea first appears in the upper cambrian, and persists to the present time. in north america the genus _dendrocrinus_ occurs in the cambrian and ordovician; and some stem-joints from the upper cambrian limestone of the mount wellington district, victoria, may be provisionally referred to this genus. [illustration: =fig. .--fossil crinoids.= a--(?) pisocrinus yassensis, eth. fil. side of calyx. silurian. yass, new south wales. b--(?) pisocrinus yassensis, eth. fil. dorsal surface. silurian. n. s. w. c--botryocrinus longibrachiatus, chapm. silurian. flemington, vict. d--helicocrinus plumosus, chapm. stem, distal end. brunswick, victoria. e--phialocrinus konincki, eth. fil. carbopermian (up. mar. ser.) nowra, new south wales. f--isocrinus australis, moore sp. l. cretaceous. wollumbilla, q'ld. ] =ordovician crinoids.--= no undoubted crinoid remains have been found in the australian ordovician; although many genera are found elsewhere in that system, chiefly in n. america, as _reteocrinus_, _hybocrinus_, _heterocrinus_ and _dendrocrinus_, and in europe and north america, as _rhodocrinus_ and _taxocrinus_. =silurian crinoids.--= the silurian crinoidea of australia are largely represented by the remains of the columns or stalks, which are often found in such abundance as to constitute large masses of sub-crystalline limestone, as that of toongabbie, victoria. the columns of the crinoids do not usually possess sufficient characters to enable the forms to be identified. there are, however, more perfect and identifiable remains of several very interesting generic types in the silurian faunas as follows:-- in new south wales _pisocrinus_ is represented with some reservation by (?) _p. yassensis_, found at limestone creek, near yass (fig. a, b). in victoria, _helicocrinus plumosus_ and _botryocrinus longibrachiatus_ occur at brunswick and flemington, respectively (fig. ). the former is a delicate and handsome species, having a small cup with finely pinnate arms, which are forked once, and with a pentagonal stem coiled at the distal end (see frontispiece). the genus _botryocrinus_ is found in rocks of a similar age in north america and england. _hapalocrinus victoriae_, a member of the platycrinidae, has been described from the mudstone of south yarra, near melbourne. the species above mentioned are of melbournian age, belonging to the lower stage of the silurian system. =devonian crinoids.--= in the middle devonian of queensland, fragmentary crinoid stems are found interbedded with the limestone of the broken river. thin slices of the limestone of the same age from buchan, victoria, show numerous ossicles and stem-joints of crinoids. similar remains have also been recorded from the devonian of the kimberley district and the gascoyne river in western australia. =carboniferous crinoids.--= the carboniferous (star beds) of queensland has yielded remains of _actinocrinus_. the matai series of new zealand, which may be regarded as almost certainly of carboniferous age, contains remains of a _cyathocrinus_, found in the limestone of the wairoa gorge. =carbopermian crinoids.--= the carbopermian (upper marine series) of new south wales yields the interesting crinoid having a large, globular cup, known as _phialocrinus_; the best known species of this genus are _p. konincki_ (fig. e) and _p. princeps_. beds of the same age in new south wales, also in the upper marine series, contain the aberrant crinoid with strongly sculptured plates of the calyx in the decorticated condition, _tribrachiocrinus clarkei_. _poteriocrinus_ and _platycrinus_ are, with some reservation, recorded from the gympie series at stanwell and the marine beds of the bowen river coal-field respectively, both in queensland. in western australia the carbopermian rocks of the gascoyne river are known to contain crinoid stems, tentatively referred to either the rhodocrinidae or the actinocrinidae. there is also a species of _platycrinus_ known from the gascoyne and irwin rivers, and from the kimberley district. =triassic crinoids.--= the kaihiku series of nelson, new zealand, has yielded some crinoid stems, but the genus has not yet been determined. =cretaceous crinoids.--= in the lower cretaceous limestone of queensland, at mitchell downs and wollumbilla, a typical crinoid, closely allied to the living _pentacrinus_ is found, namely, _isocrinus australis_ (fig. f). the upper cretaceous opal deposits of white cliffs in wilcannia, new south wales, contain many opalised fossil remains, amongst them being _isocrinus australis_, already noticed as occurring in the lower cretaceous of queensland. =cainozoic crinoids.--= _pentacrinus stellatus_ is a species founded on some deeply indented pentagonal stem-joints found in the oamaru series (miocene) at curiosity shop, south canterbury, new zealand, and also occurring in the chatham islands. this species has been identified in the aire coastal beds in victoria, of the same age. another generic type, _antedon_, the beautiful "feather star," is frequently met with in janjukian strata in victoria and south australia, as at batesford and mount gambier, represented by the denuded crown and the ossicles of the arms of a comparatively large species; whilst another and smaller form has been described from beds of the same age from borings in the victorian mallee, under the name of _a. protomacronema_. _blastoidea--bud-shaped echinoderms._ =distribution and characters of blastoidea.--= this forms a small class which has a few representatives in the rocks of australia. elsewhere they are chiefly of devonian and carboniferous ages. in australia they are confined, so far as known, to sediments of the carboniferous system. the animal was rooted to the sea-floor and a jointed stem was usually present. the cup or theca, as before noted, is bud-shaped, and consists of basal, radial and deltoid plates, the edges of which are folded inwards into the thecal cavity, and thus the internal organs came into contact with the incurrent water. the cup bears five food grooves, bordered by numerous arms or brachioles, which directed the incurrent particles into the thecal cavity. =carbopermian blastoids.--= three genera of blastoids have been recorded from the gympie beds, or carbopermian, of the rockhampton district of queensland. they are, _mesoblastus_, _granatocrinus_ and _tricoelocrinus_. a similar fossil in beds of like age, and provisionally referred to the genus _metablastus_, has been lately recorded from glenwilliam, clarence town, new south wales. _asteroidea, or starfishes._ =characters of true starfishes.--= these free-moving echinoderms are usually five-sided, though sometimes star-shaped, with numerous arms surrounding a central disc. the mouth is central on the under side of the disc, and the anus above and near the centre (excentric), the latter being covered by a porous plate called the madreporite. the hydraulic system of starfishes consists of tubes extending along the grooved arms and giving off side branches which end in processes called podia and terminating in suckers. the podia pass through pores in the floor plates of the grooves, and communicate within the body with distensions called ampulla. by this means the podia serve as feet, and can be withdrawn by the expulsion of the water in them into the ampulla. the stout flexible covering of the starfish is strengthened by calcareous plates and bars, owing to the presence of which they are often preserved as fossils. [illustration: =fig. .--fossil starfish.= a--palaeaster smythi. mccoy sp. silurian. flemington, victoria. b--urasterella selwyni, mccoy. silurian. kilmore, victoria. c--palaeaster giganteus, eth. fil. carbopermian. near farley, new south wales. d--pentagonaster sp. tertiary (janjukian). bore in mallee, victoria. ] =silurian starfishes.--= the oldest australian fossil starfishes are found in the silurian. in victoria they occur in some abundance in the lower, melbournian, series, but appear to be absent or at all events very scarce in the upper, or yeringian series. the commonest genus is _palaeaster_, of which there are two species, _p. smythi_ (fig. a) and _p. meridionalis_, found alike in the sandy and argillaceous strata near melbourne. _urasterella_ is another genus found in the silurian rocks near melbourne, in which the marginal series of plates seen in _palaeaster_ are wanting, giving to the starfish a slender, long-armed aspect (fig. b). =carbopermian starfishes.--= in the lower marine series of the carbopermian of new south wales a very large species of _palaeaster_ occurs (_p. giganteus_), measuring inches from point to point across the disc (fig. c). two other species of the same genus occur in this series (_p. stutchburii_ and _p. clarkei_) the latter also ranging into the upper marine series. =cainozoic starfishes.--= no remains of true starfishes have been recorded from australia between the carbopermian and the tertiary systems. in the janjukian series of victoria the marginal plates of a species of _pentagonaster_ are typical fossils. they have been recorded from waurn ponds, spring creek near torquay, and batesford (fig. d). in the mallee bores, both marginal and abactinal plates of this genus are found in polyzoal limestone (miocene). _pentagonaster_ also occurs in the lower muddy creek beds (oligocene), and the upper beds of the same locality (lower pliocene). a species of _astropecten_ has been described from the waikari river, new zealand (oamaru series). _ophiuroidea, or brittle-stars._ =characters of brittle-stars.--= the brittle-stars are frequently found at the present day cast up on the fine sandy beaches of the coast. they are easily distinguished from true starfishes by having a definite central disc, to which the arms are attached. the arms are used for locomotion and prehension, and have their grooves covered over with plates. the ossicles of the arms are moveable and controlled by muscles which enable them to be used as feet. the lower surface of the disc has a central arrangement of five rhomboidal sets of jaws, formed of modified ossicles, called the mouth frame, whilst the upper surface bears, between one set of arms, the madreporite or covering plate to the water vascular system, as in starfishes. [illustration: =fig. .--protaster brisingoides=, gregory. negative cast of the calcareous skeleton. nat. size. silurian sandstone, flemington, victoria. (_nat. mus. coll._) ] =silurian brittle-stars.--= the brittle-stars in australia first appear in the silurian, but in england and bohemia date back to the ordovician. _protaster_ is the commonest genus, and is represented by _p. brisingoides_ of the melbournian stage of silurian strata at flemington (fig. ). it also occurs rarely in the yeringian beds at yering, both victorian localities. a very ornamental form, _gregoriura spryi_, occurs in the same division of the silurian at south yarra. in this fossil the delicate spines attached to the adambulacral ossicles are well preserved and form a marginal fringe to the arm (fig. ). _sturtzura_ is another silurian genus, found in the wenlock of england and in the melbournian of flemington, victoria. [illustration: =fig. .--a brittle-star.= (gregoriura spryi, chapm.) nat. size. from the silurian mudstone of south yarra, victoria. (_nat. mus. coll._) ] =cainozoic brittle-stars.--= from the victorian cainozoic beds, in the lower pliocene of grange burn, hamilton, a vertebral ossicle of an ophiurian has been obtained, which has been provisionally referred to the genus _sigsbeia_. _echinoidea, or sea-urchins._ this group is an important one amongst australian fossils, especially those of cainozoic age. =characters of sea-urchins.--= echinoids are animals enclosed in a spheroidal box or test composed of numerous calcareous plates, disposed geometrically as in the starfishes, along five principal lines. the test in the living condition is more or less densely covered with spines. the mouth is on the under surface. the anus is either on the top of the test (dorso-central), or somewhere in the median line between the two lower ambulacra. the ambulacra ("a garden path") are the rows of perforated plates on the upper (abactinal) surface sometimes extending to the lower surface, through which protrude the podia, which in starfishes are situated in grooves on the lower surface. =silurian palaeechinoids.--= the palaeechinoids are represented in the silurian of australia by occasional plates, as at bowning, new south wales, and near kilmore, victoria, whilst spines are not uncommon in certain silurian limestones at tyer's river, gippsland. =carbopermian palaeechinoids.--= in the carbopermian of new south wales, tests of _archaeocidaris_ have been recorded, and also a plate of the same genus in the gympie beds of rockhampton, queensland. =regular echinoids.--= the regular echinoids date from permian times. they have two vertical rows of plates for each ambulacrum and inter-ambulacrum. the mouth is on the underside, and the anus abactinal (on the upper side) and near the centre. [illustration: =fig. .--cainozoic sea-urchins.= a--cidaris (leiocidaris) australiae, duncan sp. cainozoic (janjukian). cape otway, victoria b--psammechinus woodsi, laube. cainozoic (janjukian). murray river cliffs, s. australia c--fibularia gregata, tate. cainozoic (janjukian). aldinga, s.a. d--echinocyamus (scutellina) patella, tate sp. cainozoic (janjukian). torquay, victoria e--clypeaster gippslandicus, mccoy. cainozoic (janjukian). bairnsdale, victoria f--studeria elegans, laube. sp. cainozoic (janjukian). murray river cliffs, s. australia. ] =cainozoic regular echinoids.--= in australasia they make their first appearance in strata of tertiary age, and some species, as _paradoxechinus novus_, range through balcombian strata to kalimnan in victoria, or oligocene to lower pliocene, but are more typically janjukian. _echinus_ (_psammechinus_) _woodsi_ (fig. b) is common in janjukian strata in victoria and south australia and occurs sparingly in the kalimnan. another common form of the regular echinoids in southern australia is _cidaris australiae_ (fig. a), ranging from janjukian to kalimnan, occurring more frequently in the older series. in new zealand a species of _cidaris_ (_c. striata_), is known from the oamaru series at brighton. an _echinus_ occurs in the oamaru series of broken river, and two species of that genus in the wanganui formation of shakespeare cliff. _temnechinus macleayana_ has been recorded from the cainozoic (miocene or pliocene) of yule island, papua. =irregular echinoids.--= the irregular echinoids are not known before the upper cretaceous in australia, and are very common in the tertiaries. they are distinguished by the anus (periproct) passing backward from the apex, as compared with the regular forms, and by the elongation of the test and the loss of the strong solid spines, which are replaced by thin, slender hair-like spines. the animal is thus better fitted to burrow through the ooze on which it feeds. =cretaceous irregular echinoids.--= an interesting form, _micraster sweeti_, is found in the upper cretaceous or desert sandstone of maryborough in queensland, which reminds one of typical european species of this genus. =cainozoic irregular echinoids.--= amongst the australian cainozoic echinoids of the irregular type the following may be mentioned. the little subglobular test of _fibularia gregata_, and _echinocyamus_ (_scutellina_) _patella_ (fig. c, d) are janjukian in age. the large _clypeaster, c. gippslandicus_ (fig. e), ranges from the oligocene to lower pliocene in victoria (balcombian to kalimnan), and vies in size, especially in the janjukian, with some large species like those from malta and egypt. this genus includes some of the largest known sea-urchins. the biscuit urchin, _arachnoides (monostychia) australis_, is commonest in the janjukian, but ranges from balcombian to kalimnan. a common urchin from the polyzoal rock of mt. gambier is _echinolampas gambierensis_, which is also found in the lower beds of muddy creek. a typical janjukian fossil is _duncaniaster australiae_, formerly thought to belong to the cretaceous genus _holaster_. although found living, the genus _linthia_ attained its maximum development both in size and abundance, in janjukian or miocene times, as seen in _l. gigas_ (having a length of - / inches) and _l. mooraboolensis_. _echinoneus dennanti_ is restricted to the janjukian. several species of _eupatagus_ occur in the cainozoic or tertiary beds of south australia, victoria and new zealand; _lovenia forbesi_ (fig. c) is common in the janjukian to kalimnan, both in victoria and south australia. in the latter state also occur the following genera:--_studeria_, _cassidulus_, _echinolampas_, _plesiolampas_, _linthia_, _schizaster_ and _brissopsis_. in new zealand the following cainozoic genera, amongst others of the irregular sea-urchins, may be cited:--_hemipatagus_, _brissopsis_, _hemiaster_, and _schizaster_ (fig. ). [illustration: =fig. --cainozoic sea-urchins.= a--hemiaster planedeclivis, gregory. cainozoic (janjukian). morgan, s. australia b--schizaster sphenoides, t. s. hall. cainozoic (barwonian). sherbrooke river, victoria c--lovenia forbesi, t. woods sp. cainozoic (janjukian). murray river cliffs, s. australia ] a clypeastroid, _peronella decagonalis_ has been described from the (?) lower pliocene of papua. =cainozoic holothuroidea.--= the _holothuroidea_ (sea-cucumbers) are represented in australian deposits by a unique example of a dermal spicule of wheel-like form, referred to _chiridota_, obtained from the cainozoic (janjukian) beds of torquay. this genus is also known from the "calcaire grossier" or middle eocene of the paris basin, and is found living in all parts of the world. * * * * * common or characteristic fossils of the foregoing chapter. crinoids. (?) _pisocrinus yassensis_, eth. fil. silurian: new south wales. _helicocrinus plumosus_, chapman. silurian: victoria. _botryocrinus longibrachiatus_, chapm. silurian: victoria. _hapalocrinus victoriae_, bather. silurian: victoria. _actinocrinus_ sp. carboniferous: queensland. _cyathocrinus_ sp. carboniferous: new zealand. _phialocrinus konincki_, clarke sp. carbopermian: new south wales. _phialocrinus princeps_, eth. fil. carbopermian: new south wales. _tribrachiocrinus clarkei_, mccoy. carbopermian: new south wales. (?) _platycrinus_ sp. carbopermian: queensland. _platycrinus_ sp. carbopermian: w. australia. _isocrinus australis_, moore sp. cretaceous: queensland. _pentacrinus stellatus_, hutton. miocene: new zealand, chatham ids. and victoria. _antedon protomacronema_, chapman. miocene: victoria (deep borings). blastoids. (?) _mesoblastus australis_, eth. fil. carbopermian: queensland. starfishes. _palaeaster smythi_, mccoy. silurian: victoria. _palaeaster meridionalis_, eth. fil. silurian: victoria. _urasterella selwyni_, mccoy. silurian: victoria. _palaeaster giganteus_, eth. fil. carbopermian (l. mar. ser.): new south wales. _palaeaster clarkei_, de koninck. carbopermian (l. and up. mar. ser.): new south wales. _pentagonaster_ sp. miocene: victoria. _astropecten_ sp. miocene: new zealand. brittle-stars. _protaster brisingoides_, gregory. silurian: victoria. _gregoriura spryi_, chapman. silurian: victoria. _sturtzura leptosomoides_, chapman. silurian: victoria. (?) _sigsbeia_ sp. lower pliocene: victoria. echinoids. _palaeechinus_ sp. silurian: victoria. (?) _archaeocidaris selwyni_, eth. fil. carbopermian: new south wales. _micraster sweeti_, eth. fil. cretaceous: queensland. _cidaris (leiocidaris) australiae_, duncan. miocene and lower pliocene: victoria and s. australia. _cidaris striata_, hutton. miocene: new zealand. _echinus (psammechinus) woodsi_, laube sp. miocene and l. pliocene: victoria and s. australia. _temnechinus macleayana_, t. woods. cainozoic (? lower pliocene): papua. _fibularia gregata_, tate. miocene: victoria and s. australia. _echinocyamus (scutellina) patella_, tate sp. oligocene to miocene: victoria and s. australia. _clypeaster gippslandicus_, mccoy. oligocene to l. pliocene: victoria. _arachnoides (monostychia) australis_, laube sp. oligocene to l. pliocene: victoria and s. australia. _echinoneus dennanti_, hall. miocene: victoria. _duncaniaster australiae_, duncan sp. miocene: victoria. _lovenia forbesi_, t. woods sp. miocene and l. pliocene: victoria and s. australia. _hemiaster planedeclivis_, gregory. miocene: victoria. holothurian. _chiridota_ sp. miocene: victoria. * * * * * literature. crinoids. silurian.--etheridge, r. jnr. rec. austr. mus., vol. v. no. , , pp. - (_pisocrinus_). bather, f. a. geol. mag., dec. xv. vol. iv. , pp. - (_hapalocrinus_). chapman, f. proc. r. soc. vict., vol. xv. (n.s.), pt. ii. , pp. - (_helicocrinus_ and _botryocrinus_). bather, f. a. ottawa nat., vol. xx. no. , , pp. , . carboniferous and carbopermian.--de koninck, l. g. mem. geol. surv. new south wales, pal. no. , , pp. - . etheridge, r. jnr., in geol. and pal. queensland, , pp. - . idem, mem. geol. surv. new south wales, pal. no. , , pp. - . cretaceous.--moore, c. quart. journ. geol. soc., vol. xxvi. , p. . etheridge, r. jnr., in geol. and pal. queensland, , p. (_isocrinus_). cainozoic.--hutton, f. w. cat. tert. moll. and ech. of new zealand, , p. . blastoids. carbopermian.--etheridge, r. jnr., in geol. and pal. queensland, , pp. - . taylor, t. g. proc. linn. soc. new south wales, , pp. - (_? metablastus_). starfishes. silurian.--mccoy, f. prod. pal. vict., dec. i., , pp. - . etheridge, r. jnr. rec. austr. mus., vol. i., no. , , pp. , . carboniferous and carbopermian.--etheridge, r. jnr. mem. geol. surv. new south wales, pal. no. , pt. , , pp. - . de koninck, l. g. ibid., pal. no. , , p. . cainozoic.--hall, t. s. proc. r. soc., vict., vol. xv. (n.s.), pt. i. , pp. , (_pentagonaster_). hutton, f. w. cat. tert. moll, and ech. new zealand, , p. . brittle-stars. silurian.--gregory, j. w. geol. mag., dec. iii. vol. vi. , pp. - . chapman, f. proc. r. soc. vict., vol. xix. (n.s.), pt. ii. , pp. - . cainozoic.--hall, t. s. proc. r. soc. vict., vol. xv. (n.s.), pt. i. , p. (cf. _sigsbeia_). echinoids. silurian.--chapman, f. rec. geol. surv. vict., vol. ii. pt. , , pp. , . carbopermian.--etheridge, r. jnr. mem. geol. surv. new south wales, pal. no. , pt. , , pp. - . cretaceous.--etheridge, r. jnr., in geol. and pal. queensland, , pp. , . cainozoic.--t. woods. trans. adelaide phil. soc., . laube, g. c. sitz, k. k. ak. wiss. wien, vol. lix. , pp. - . hutton, f. w. cat. tert. moll, and ech. new zealand, , pp. - . duncan, p. m. quart. journ. geol. soc., vol. xxxiii. , pp. - . tate, r. quart. journ. geol. soc., vol. xxxiii. , pp. - . idem, southern science record, , p. . idem, trans. r. soc. s. austr., vol. xiv. pt. , , pp. - . mccoy, f. prod. pal. vict., dec. vi. vii. , . gregory, j. w. geol. mag., dec. iii. vol. vii. , pp. - . ibid., dec. iii. vol. ix. , pp. - . cotteau, g. h. mem. zool. france, vol. ii. no. , , p. ; vol. iii. no. , , pp. - ; vol. iv. no. , , pp. - . bittner, a. sitz. k.k. ak. wiss. wien, , vol. , pp. - . hall, t. s. proc. roy. soc. vic., vol. xix. (n.s.), pt. ii. , pp. , . chapman, f. proc. roy. soc. vict., vol. xx. (n.s.), pt. ii. , pp. - . pritchard, g. b. ibid., vol. xxi. (n.s.), pt. i. , pp. - . holothurian. cainozoic.--hall, t. s. proc, r. soc. vict., vol. x. (n.s.), pt. i. , pp. , . chapter ix. fossil worms, sea-mats and lamp-shells. the first-named group, the ringed worms, belong to the phylum annelida, so-called because of the ring-like structure of their bodies. the two remaining groups, the polyzoa or sea-mats and the brachiopods or lamp-shells, are comprised in the phylum molluscoidea, or mollusc-like animals. _worms (annelida)._ =annelida and their fossil representatives.--= these animals, owing to the scarcity of hard parts within their bodies, play a rather insignificant role as a fossil group. worms are laterally symmetrical animals, with a dorsal and a ventral surface. they are segmented, the body being formed of numerous rings. only those of the class chaetopoda ("bristle-feet") are represented by identifiable fossil remains. fossil worms, moreover, chiefly belong to the order polychaeta ("many bristles"). the horny jaws of these worms are sometimes found in the older rocks and are known as conodonts. =silurian conodonts.--= conodonts belonging to three genera are known from australia. they are all from the silurian of the bowning district, near yass, new south wales, and are referred to the genera _eunicites_, _oenonites_ and _arabellites_. [illustration: =fig. --fossil worms.= a--trachyderma crassituba, chapm, silurian. south yarra, vict. b--cornulites tasmanicus, eth. fil. silurian. heazlewood, tas. c--spirorbis ammonius, m. edwards, var. truncata, mid. devonian. buchan, victoria d--torlessia mackayi, bather. ? trias. mt. torlesse, n. zealand. ] =palaeozoic errant worms.--= the wandering worms (polychaeta errantia) are also recognised by their impressions, trails, borings and castings. burrows formed by these worms are seen in _arenicolites_, found in the silurian sandstone of new south wales, near yass, and in the carbopermian (gympie series) near rockhampton, queensland. the membranous-lined burrows of _trachyderma_ (_t. crassituba_), occur in some abundance in the silurian mudstones in the neighbourhood of melbourne, victoria (fig. a). the genus _trachyderma_ is common also to great britain and burmah, in beds of the same age. =worm tracks.--= some of the curious markings on the carboniferous sandstone of mansfield, victoria, may be due to worm trails and castings, especially since they are associated with sun-cracks and ripple-marks. =sedentary worms.--= the sedentary or tube-making worms (polychaeta tubicola) are represented by numerous forms. the long conical tube of _cornulites tasmanicus_ is recorded from the silurian of zeehan, tasmania (fig. b). _spirorbis_ occurs in the middle devonian of victoria (fig. c), and w. australia, and also in the carbopermian of w. australia. _torlessia_ is found in the trias or lower jurassic of the province of canterbury, new zealand (fig. d). the genus _serpula_ is widely distributed, occurring in the carbopermian (upper jurassic series), near east maitland, new south wales (_s. testatrix_), in the jurassic of w. australia (_s. conformis_), in the lower cretaceous of wollumbilla, queensland (_s. intestinalis_), and the darling river, north west of new south wales, (_s. subtrachinus_), as well as in cainozoic deposits in victoria (_s. ouyenensis_). _ditrupa_ is very abundant in some shelly deposits of janjukian age in victoria. molluscoidea. the sea-mats (polyzoa) and the lamp-shells (brachiopoda) constitute a natural group, the molluscoidea, which, although unlike in outward form, have several physiological structures in common. the respiratory organs lie in front of the mouth, and are in the form of fleshy tentacles or spiral appendages. these animals are more nearly allied to the worms than to the molluscs. _polyzoa._ =characters of polyzoa.--= these are almost exclusively marine forms, and are important as fossils. they form colonies (polypary or zoarium), and by their branching, foliaceous or tufty growth resemble sea-weeds. the cells in which the separate zoöids lived have peculiar characters of their own, which serve to distinguish the different genera. =subdivisions of polyzoa.--= polyzoa are divided into the sub-classes phylactolaemata, in which the mouth of the zoöid has a lip, and the series of tentacles is horse-shoe shaped; and the gymnolaemata, in which there is no lip to the mouth, and the tentacles form a complete circle. the first group forms its polypary of soft or horny material, which is not preserved fossil. the latter has a calcareous polypary, and is of much importance as a fossil group. this latter sub-class is further subdivided into the following orders, viz.:--trepostomata ("turned mouths"), cryptostomata ("hidden mouths"), cyclostomata ("round mouths"), and cheilostomata ("lip mouths" furnished with a moveable operculum). =trepostomata (palaeozoic).--= the order trepostomata may include some genera as _monticulipora_ and _fistulipora_, previously referred to under the corals. they become extinct after permian times. _fistulipora_ occurs in certain gippsland limestones. [illustration: =fig. --palaeozoic polyzoa.= a--fenestella margaritifera, chapm. silurian. near yering, vict. b--polypora australis, hinde. carbopermian. gascoyne river, western australia c--rhombopora tenuis, hinde. carbopermian. gascoyne river, western australia d--protoretepora ampla, lonsdale sp. carbopermian. n.s.w. ] =cryptostomata (palaeozoic).--= in the order cryptostomata we have the genus _rhombopora_ with its long, slender branches, which occurs in the silurian of victoria and the carbopermian of queensland and w. australia (fig. c). of this order a very important australian genus is _fenestella_, the funnel-shaped zoaria of which are found in the silurian of victoria and new south wales, and also in the carboniferous of the latter state. _fenestella_ also occurs in the carbopermian of w. australia and tasmania (fig. a). accompanying the remains of _fenestella_ in the carbopermian rocks, and closely related to it, are found the genera _protoretepora_ and _polypora_ (fig. b, d). polyzoa have been noticed in jurassic rocks in w. australia, but no species have been described. [illustration: =fig. --cainozoic polyzoa.= a--lichenopora australis, macgillivray. balcombian. hamilton, victoria b--heteropora pisiformis, macgillivray. janjukian. moorabool, victoria c--cellaria australis, macgillivray. balcombian. hamilton, vict. d--selenaria cupola, t. woods sp. balcombian. hamilton, vict. e--lepralia elongata, macgill. balcombian. hamilton, victoria ] =cheilostomata (cretaceous).--= species of the genera (?) _membranipora_ and (?) _lepralia_, belonging to the cheilostomata, have been described from the lower cretaceous of the darling river, new south wales, and wollumbilla, queensland, respectively. =cainozoic polyzoa.--= a very large number of genera of the polyzoa have been described from the tertiary strata of south australia and victoria. some of the principal of these are _crisia_, _idmonea_, _stomatopora_, _lichenopora_, _hornera_, _entalophora_ and _heteropora_ of the order cyclostomata; and _catenicella_, _cellaria_, _membranipora_, _lunulites_, _selenaria_, _macropora_, _tessarodoma_, _adeona_, _lepralia_, _bipora_, _smittia_, _porina_, _cellepora_ and _retepora_ of the order cheilostomata. many of these genera, and not a few australian species, are found also in the cainozoic or tertiary beds of orakei bay, new zealand (fig. ). _brachiopoda (lamp-shells)._ =brachiopods: their structure.--= these are marine animals, and are enclosed in a bivalved shell. they differ, however, from true bivalves (pelecypoda) in having the shell on the back and front of the body, instead of on each side as in the bivalved mollusca. each valve is equilateral, but the valves differ from one another in that one is larger and generally serves to attach the animal to rocks and other objects of support by a stalk or pedicle. thus the larger valve is called the pedicle valve and the smaller, on account of its bearing the calcareous supports for the brachia or arms, the brachial valve. generally speaking, the shell of the valve is penetrated by numerous canals, which give the shell a punctate appearance. some brachiopod shells, as _atrypa_ and _rhynchonella_, are, however, devoid of these. [illustration: =fig. --lower palaeozoic brachiopods.= a--orthis (?) lenticularis, wahlenberg. up. cambrian. florentine valley, tasmania b--siphonotreta maccoyi, chapm. up. ordovician. bulla, vict. c--lingula yarraensis, chapm. silurian. south yarra, victoria d--orbiculoidea selwyni, chapm. silurian. merri creek, victoria e--chonetes melbournensis, chapm. silurian. south yarra, vict. f--stropheodonta alata, chapm. silurian. near lilydale, vict. ] =cambrian brachiopods.--= brachiopods are very important fossils in australasian rocks. they first appear in cambrian strata, as for example, in the florentine valley, in tasmania, where we find _orthis lenticularis_ (fig. a). in victoria, near mount wellington, in the mountainous region of n.e. gippsland, _orthis platystrophioides_ is found in a grey limestone. in south australia the grey cambrian limestone of wirrialpa contains the genus _huenella_ (_h. etheridgei_). this genus is also found in the middle and upper cambrian of n. america. =ordovician brachiopods.--= coming to ordovician rocks, the limestones of the upper finke basin in south australia contain _orthis leviensis_ and _o. dichotomalis_. the victorian mudstone at heathcote may be of ordovician age or even older; it has afforded a limited fauna of brachiopods and trilobites, amongst the former being various species of _orthis_, _chonetes_, and _siphonotreta_. the latter genus is represented in both the lower and upper ordovician rocks of slaty character in victoria (fig. b). =silurian brachiopods.--= the silurian system in australasia as in europe, n. america and elsewhere, is very rich in brachiopod life. it is impossible to enumerate even all the genera in a limited work like the present, the most typical only being mentioned. in new zealand the palaeozoic fauna is at present imperfectly worked out, but the following genera from the wangapekian (silurian) have been identified, viz., _chonetes_, _stricklandinia_, _orthis_, _wilsonia_, _atrypa_, and _spirifer_. the specific identification of these forms with european types is still open to question, but the species are undoubtedly closely allied to some of those from great britain and scandinavia. the victorian silurian brachiopods are represented by the horny-shelled _lingula_, the conical _orbiculoidea_, a large species of _siphonotreta_, _stropheodonta_ (with toothed hinge-line), _strophonella_, _chonetes_ (with hollow spines projecting from the ventral valve, one of the species _c. melbournensis_ being characteristic of the melbournian division of silurian rocks), _orthis_, _pentamerus_, _camarotoechia_, _rhynchotrema_, _wilsonia_, _atrypa_ (represented by the world-wide _a. reticularis_), _spirifer_ and _nucleospira_ (figs. , ). new south wales has a very similar assemblage of genera; whilst tasmania possesses _camarotoechia_, _stropheodonta_ and _orthis_. =devonian brachiopods.--= the devonian limestones and associated strata are fairly rich in brachiopods. the victorian rocks of this age at bindi and buchan contain genera such as _chonetes_ (_c. australis_), _spirifer_ (_s. yassensis_ and _s. howitti_) and _athyris_. in new south wales we again meet with _spirifer yassensis_, veritable shell-banks of this species occurring in the neighbourhood of yass, associated with a species of _chonetes_ (_c. culleni_) (fig. d, e). [illustration: =fig. --silurian and devonian brachiopods.= a--camarotoechia decemplicata, sow. silurian. victoria b--nucleospira australis, mccoy. silurian. victoria c--atrypa reticularis, l. sp. silurian. victoria d--chonetes culleni, dun. mid. devonian. new south wales e--spirifer yassensis, de koninck. devonian. new south wales and victoria ] in the upper devonian of new south wales abundant remains occur of both _spirifer disjunctus_ and _camarotoechia pleurodon_ (var.). the upper devonian series at nyrang creek near canowindra, new south wales, contains a _lingula_ (_l. gregaria_) associated with the _lepidodendron_ plant beds of that locality. queensland devonian rocks contain _pentamerus_, _atrypa_ and _spirifer_. in western australia the devonian species are _atrypa reticularis_, _spirifer_ cf _verneuili_, _s. musakheylensis_ and _uncinulus_ cf. _timorensis_. =carboniferous brachiopods.--= the carboniferous brachiopod fauna is represented in new south wales at clarence town and other localities by a species which has an extensive time-range, _leptaena rhomboidalis_ var. _analoga_, and the following, a few of which extend upwards into the carbopermian:--_chonetes papilionacea_, _productus semireticulatus_, _p. punctatus_, _p. cora_, _orthothetes crenistria_, _orthis (rhipidomella) australis_, _o. (schizophoria) resupinata_, _spirifer striatus_, _s. bisulcatus_, _cyrtina carbonaria_ and _athyris planosulcatus_. in new zealand the matai series, referred to the jurassic by hutton, as formerly regarded by hector, and latterly by park, as of carboniferous age, on the ground of a supposed discovery of _spirifer subradiatus_ (_s. glaber_) and _productus brachythaerus_ in the wairoa gorge. although these species may not occur, the genera _spirifer_ and _productus_ are present, which, according to dr. thomson, are distinctly of pre-triassic types. [illustration: =fig. --carbopermian brachiopods.= a--productus brachythaerus, sow. carbopermian. new south wales, &c. b--strophalosia clarkei, eth. sp. carbopermian. n.s.w., &c. c--spirifer convolutus, phillips. carbopermian. n.s.w., &c. d--spirifer (martiniopsis) subradiatus, sow. carbopermian. new south wales, &c. ] =carbopermian brachiopods.--= the brachiopod fauna of carbopermian age in new south wales is rich in species of _productus_ and _spirifer_. amongst the former are _p. cora_ (also found in western australia, queensland and tasmania), _p. brachythaerus_ (also found in western australia and queensland), (fig. a), _p. semireticulatus_ (also found in western australia, queensland and the island of timor, and a common species in europe), and _p. undatus_ (also found in western australia and queensland, as well as in great britain and russia). _strophalosia_ is an allied genus to _productus_. it is a common form in beds of the same age in w. australia, tasmania, and new south wales. the best known species is _s. clarkei_ (fig. b). this type of shell is distinguished from _productus_ in being cemented by the umbo of the ventral valve, which valve is also generally less spinose than the dorsal. when weathered the shells present a peculiar silky or fibrous appearance. the genus _spirifer_ is represented in w. australia by such forms as _s. vespertilio_, _s. convolutus_, _s. hardmani_, _s. musakheylensis_, and _s. striatus_; whilst _s. vespertilio_ and _s. convolutus_ are common also to new south wales (fig. c), and the latter only to tasmania. _s. vespertilio_ is found in the gympie beds near rockhampton, queensland; and _s. tasmaniensis_ in queensland (bowen river coal-field, marine series), new south wales and tasmania. of the smoother, stout forms, referred to the sub-genus _martiniopsis_, we may mention _s. (m.) subradiatus_, which occurs in w. australia, new south wales, and tasmania (fig. d). in the queensland fauna, the gympie series contains, amongst other brachiopods _productus cora_, _leptaena rhomboidalis_ var., _analoga_, _spirifer vespertilio_ and _s. strzeleckii_. other carbopermian brachiopod genera found in australian faunas are _cleiothyris_, _dielasma_, _hypothyris_, _reticularia_, _seminula_, _cyrtina_, and _syringothyris_. =triassic brachiopods.--= the kaihiku series of new zealand (hokonui hills and nelson) are probably referable to the trias. the supposed basal beds contain plants such as _taeniopteris_, _cladophlebis_, _palissya_ and _baiera_. above these are marine beds containing brachiopods belonging to _spiriferina_, _rhynchonella_, _dielasma_ and _athyris_. the succession of these beds presents some palaeontological anomalies still to be explained, for the flora has a decided leaning towards a jurassic facies. next in order of succession the wairoa series, in the hokonui hills and nelson, new zealand, contains _dielasma_ and _athyris wreyi_. the succeeding series in new zealand, the otapiri, or upper triassic contains the brachiopod genera _athyris_[ ] and _spiriferina_, found at well's creek, nelson. [footnote : referred by hector to a new sub-genus _clavigera_, which name, however, is preoccupied.] =jurassic brachiopods.--= [illustration: =fig. --mesozoic brachiopods.= a--rhynchonella variabilis schloth. sp. jurassic. w. australia b--terebratella davidsoni, moore. l. cretaceous. queensland c--lingula subovalis, davidson. l. cretaceous. s. australia d--rhynchonella croydonensis, eth. fil. up. cretaceous. queensland ] the marine jurassic beds of w. australia, as at shark bay and greenough river, contain certain _rhynchonellae_ allied to european species, as _r. variabilis_ (fig. a), and _r._ cf. _solitaria_. =lower cretaceous brachiopods.--= the lower cretaceous or rolling downs formation of queensland has yielded a fair number of brachiopods, principally from wollumbilla,--as _terebratella davidsoni_ (fig. b), (?) _argiope wollumbillensis_, (?) _a. punctata_, _rhynchonella rustica_, _r. solitaria_, _discina apicalis_ and _lingula subovalis_. from beds of similar age in central south australia and the lake eyre basin _lingula subovalis_ (fig. c), and _rhynchonella eyrei_ have been recorded; the latter has been compared with a species (_r. walkeri_) from the middle neocomian of tealby in yorkshire. =upper cretaceous brachiopod.--= a solitary species of the brachiopoda occurs in the upper cretaceous of australia, namely, _rhynchonella croydonensis_ (fig. d) of the desert sandstone of the croydon gold-fields and mount angas, queensland. =cainozoic brachiopods.--= the brachiopoda of the cainozoic or tertiary strata of australia and new zealand are well represented by the genera _terebratula_, _magellania_, _terebratulina_, _terebratella_, _magasella_ and _acanthothyris_. in the balcombian or oligocene of southern australia occur the following:--_terebratula tateana_, _magellania corioensis_, _m. garibaldiana_ and _magasella compta_ (figs. a, d); and most of these range into the next stage, the janjukian, whilst some extend even to the kalimnan. _terebratulina suessi_, hutton sp. (= _t. scoulari_, tate) ranges through the balcombian and janjukian, but is most typical of the janjukian beds in victoria: it also occurs in the oamaru series of new zealand (= janjukian). _acanthothyris squamosa_ (fig. f) is typical of the janjukian of southern australia, and it occurs also in the pareora beds of the broken river, new zealand. the latter are green, sandy, fossiliferous strata immediately succeeding the oamaru stone of the hutchinson quarry beds. _a. squamosa_ is said to be still living south of kerguelen island. _magellania insolita_ is a victorian species which is also found in the oamaru series of new zealand. [illustration: =fig. --cainozoic brachiopods.= a--terebratula tateana, t. woods. cainozoic. victoria b--magellania corioensis, mccoy, sp. cainozoic. victoria c--magellania garibaldiana, dav. sp. cainozoic. victoria d--magasella compta, sow. sp. cainozoic. victoria e--terebratulina catinuliformis, tate. cainozoic. s. australia f--acanthothyris squamosa, hutton sp. cainozoic. tasmania ] whilst many of the older tertiary brachiopods range into the next succeeding stage of the kalimnan in victoria, such as _magellania insolita_, _terebratulina_ catinuliformis_ (fig. e) and _magasella compta_, one species, _terebratella pumila_, is restricted to the kalimnan, occurring at the gippsland lakes. the next stage, the werrikooian, typical in upraised marine beds on the banks of the glenelg river in western victoria, contains _magellania flavescens_, a species still living (see _antea_, fig. ), and _m. insolita_, having the extraordinarily wide range of the whole of the cainozoic stages in southern australia. * * * * * common or characteristic fossils of the foregoing chapter. worms. _eunicites mitchelli_, eth. fil. silurian: new south wales. _oenonites hebes_, eth. fil. silurian: new south wales. _arabellites bowningensis_, eth. fil. silurian: new south wales. _arenicolites_ sp. silurian: new south wales. _trachyderma crassituba_, chapm. silurian: victoria. _cornulites tasmanicus_, eth. fil. silurian: tasmania. _spirorbis ammonius_, m. edw. var. _truncata_, chapm. mid. devonian: victoria. _spirorbis omphalodes_, goldfuss. devonian: w. australia. _serpula testatrix_, eth. fil. carbopermian: new south wales. _torlessia mackayi_, bather. lower mesozoic: new zealand. _serpula conformis_, goldfuss. jurassic: w. australia. _serpula intestinalis_, phillips. lower cretaceous: queensland. _serpula subtrachinus_, eth. fil. lower cretaceous: new south wales. _serpula ouyenensis_, chapm. cainozoic: victoria. _ditrupa cornea_, l. sp. var. _wormbetiensis_, mccoy. cainozoic: victoria. polyzoa. _rhombopora gippslandica_, chapm. silurian: victoria. _fenestella australis_, chapm. silurian: victoria. _protoretepora ampla_, lonsdale. carbopermian: w. australia, new south wales, queensland, and tasmania. _polypora australis_, hinde. carbopermian: w. australia. _rhombopora tenuis_, hinde. carbopermian: w. australia. _rhombopora laxa_, etheridge sp. carbopermian: queensland. _membranipora wilsonensis_, eth. fil. lower cretaceous: new south wales. (?) _lepralia oolitica_, moore. lower cretaceous: queensland. _lichenopora australis_, macgillivray. cainozoic: victoria. _heteropora pisiformis_, macgillivray. cainozoic: victoria. _cellaria australis_, macgillivray. cainozoic: victoria. _membranipora macrostoma_, reuss. cainozoic: victoria (also living). _selenaria marginata_, t. woods. cainozoic: victoria (also living). _macropora clarkei_, t. woods sp. cainozoic: victoria. _adeona obliqua_, macgill. cainozoic: victoria. _lepralia burlingtoniensis_, waters. cainozoic: victoria. _bipora philippinensis_, busk sp. cainozoic: victoria (also living). _porina gracilis_, m. edwards sp. cainozoic: victoria (also living). _cellepora fossa_, haswell, sp. cainozoic: victoria (also living). _retepora fissa_, macgill. sp. cainozoic: victoria (also living). brachiopoda. _orthis lenticularis_, wahlenberg sp. cambrian: tasmania. _orthis platystrophioides_, chapm. cambrian: victoria. _huenella etheridgei_, walcott. cambrian: s. australia. _orthis leviensis_, eth. fil. ordovician: s. australia, (?) victoria. _siphonotreta discoidalis_, chapm. ordovician: victoria. _siphonotreta maccoyi_, chapm. ordovician: victoria. _lingula yarraensis_, chapm. silurian: victoria. _orbiculoidea selwyni_, chapm. silurian: victoria. _chonetes melbournensis_, chapm. silurian: victoria. _stropheodonta alata_, chapm. silurian: victoria. _orthis elegantula_, dalman. silurian: victoria. _pentamerus australis_, mccoy. silurian: victoria and new south wales. _conchidium knightii_, sow. sp. silurian: victoria and new south wales. _camarotoechia decemplicata_, sow. sp. silurian: victoria. _rhynchotrema liopleura_, mccoy sp. silurian: victoria. _atrypa reticularis_, l. sp. silurian: new south wales and victoria. devonian: new south wales, w. australia and queensland. _spirifer sulcatus_, hisinger sp. silurian: victoria. _nucleospira australis_, mccoy. silurian: victoria. _chonetes australis_, mccoy. mid. devonian: victoria. _chonetes culleni_, dun. mid. devonian: new south wales. _spirifer yassensis_, de koninck. mid. devonian: new south wales and victoria. _spirifer_ cf. _verneuili_, de kon. mid. devonian: new south wales and w. australia. _lingula gregaria_, eth. fil. upper devonian: new south wales. _spirifer disjunctus_, sow. up. devonian: new south wales. _productus cora_, d'orb. carboniferous: new south wales and queensland. _orthothetes crenistria_, sow. sp. carboniferous: new south wales. _spirifer striatus_, sow. carboniferous: new south wales. _productus brachythaerus_, sow. carbopermian: new south wales, queensland, w. australia. _strophalosia clarkei_, eth. sp. carbopermian: new south wales, tasmania and w. australia. _spirifer (martiniopsis) subradiatus_, sow. carbopermian: new south wales, tasmania and w. australia. _spirifer convolutus_, phillips. carbopermian: new south wales, tasmania and w. australia. _cleiothyris macleayana_, eth. fil. sp. carbopermian: w. australia. _dielasma elongata_, schlotheim sp. trias (kaihiku series): new zealand. _athyris wreyi_, suess sp. trias (wairoa series): new zealand. _athyris_ sp. trias (otapiri series): new zealand. _rhynchonella variabilis_, schlotheim sp. jurassic: w. australia. _terebratella davidsoni_, moore. lower cretaceous: queensland. _rhynchonella solitaria_, moore. lower cretaceous: queensland. _lingula subovalis_, davidson. lower cretaceous: queensland and s. australia. _rhynchonella croydonensis_, eth. fil. upper cretaceous: queensland. _terebratula tateana_, t. woods. cainozoic (balcombian and janjukian): victoria and s. australia. _magellania corioensis_, mccoy, sp. cainozoic (balcombian and janjukian): victoria and s. australia. _magellania garibaldiana_, davidson sp. cainozoic (balcombian and janjukian): victoria and s. australia. _magasella compta_, sow. sp. cainozoic (balcombian to kalimnan): victoria and s. australia. _terebratula suessi_, hutton sp. cainozoic (balcombian and janjukian): victoria, s. australia, and new zealand (oamaru series.) _acanthothyris squamosa_, hutton sp. cainozoic (janjukian): victoria and s. australia, new zealand (oamaru series) (also living). _terebratella pumila_, tate. cainozoic (kalimnan): victoria. _magellania flavescens_, lam. sp. pleistocene: victoria (also living). * * * * * literature. worms. silurian.--etheridge, r. jnr. geol. mag., dec. iii. vol. vii. , pp. , . idem, proc. roy. soc. tas. (for ), , p. . chapman, f. proc. r. soc. vict., vol. xxii. (n.s.), pt. ii. , pp. - . devonian.--hinde, g. j. geol. mag., dec. ii. vol. vii. , p. . chapman, f. rec. geol. surv. vict., vol. iii. pt. , , p. . carboniferous.--etheridge, r. jnr. bull. geol. surv. w. australia, no. , , p. . carbopermian.--etheridge, r. jnr. mem. geol. surv. new south wales. pal. no. , , pp. - . lower mesozoic.--bather, f. a. geol. mag., dec. v. vol. ii. , pp. - . lower cretaceous.--etheridge, r. jnr. mem. soc. geol. surv. new south wales, pal. no. . , pp. , . cainozoic.--chapman, f. proc. r. soc. vict., vol. xxvi. (n.s.) pt. i. , pp. - . polyzoa. silurian.--chapman, f. proc. r. soc. vict., vol. xvi. (n.s.), pt. i. , pp. - . idem, rec. geol. surv. vic., vol. ii., pt. , , p. . carboniferous.--hinde, g. j. geol. mag. dec. iii. vol. vii. , pp. - . carbopermian.--de koninck mem. geol. surv. new south wales, pal. no. , , pp. - . cainozoic.--stolicka, f. novara exped., geol. theil., vol. i. pt. , pp. - . waters, a. w. quart. journ. geol. soc., vol. xxxvii. , pp. - ; ibid., vol. xxxviii. , pp. - and pp. - ; ibid., vol. xxxix. , pp. - ; ibid., vol. xl. , pp. - ; ibid., vol. xli. , pp. - ; ibid., vol. xliii. , pp. - and - . macgillivray, p. h. mon. tert. polyzoa vict., trans. roy. soc. vict., vol. iv. . maplestone, c. m. "further descr. polyzoa vict.," proc. roy. soc. vict., vol. xi. (n.s.), pt. i. , pp. - , et seqq. brachiopoda. cambrian.--tate, r. trans. r. soc. s. austr., vol. xv. , pp. , . etheridge, r. jnr. rec. austr. mus., vol. v. pt. , , p. . walcott, c. d. smiths. misc. coll., vol. liii. , p. . chapman, f. proc. r. soc. vic., vol. xxiii. (n.s.), pt. i. , pp. - . ordovician.--etheridge, r. jnr. parl. papers, s. aust., no. , , pp. , . tate, r. rep. horn exped., pt. , , pp. , . chapman, f. rec. geol. surv. vict., vol. i. pt. , , pp. - . silurian.--mccoy, f. prod. pal. vic. dec. v. , pp. - . eth., r. jnr. rec. geol. surv. new south wales, vol. , pt. , , pp. - (silurian and devonian _pentameridae_). idem, proc. roy. soc., tas., (for ), , pp. - . de koninck, l. g. mem. geol. surv. new south wales, pal. no. , , pp. - . dun, w. s. rec. geol. surv. new south wales, vol. vii. pt. , , pp. - (silurian to carboniferous). ibid., vol. viii. pt. , , pp. - . chapman, f. proc. r. soc. vict., vol. xvi. (n.s.), pt. , , pp. - . ibid., vol. xxi. (n.s.), pt. , , pp. , . ibid., vol. xxvi. (n.s.) pt. . , pp. - . devonian.--mccoy, f. prod. pal. vict., dec. iv., , pp. - . foord, a. h. geol. mag., dec. iii. vol. vii. , pp. - . etheridge, r. jnr. geol. and pal. queensland, , pp. - . de koninck, l. g. mem. geol. surv. new south wales, pal., no. , , pp. - . chapman, f. proc. r. soc. vict., vol. xviii. (n.s.), pt. , , pp. - . carboniferous.--etheridge, r. jnr. rec. austr. mus., vol. iv. no. , , pp. , . idem, geol. surv. w. austr., bull. no. , , pp. - . dun, w. s. rec. geol. surv. new south wales, vol. vii., pt. , , pp. - and - . carbopermian.--sowerby, g. b., in strzelecki's phys. descr. of new south wales, etc., , pp. - . mccoy, f. ann. mag. nat. hist., vol. xx. , pp. - . foord, a. h. geol. mag. dec. iii. vol. vii. , pp. and - . etheridge, r. jnr. geol. and pal. queensland, , pp. - . de koninck, l. g. mem. geol. surv. new south wales, pal., no. , , pp. - . dun, w. s. rec. geol. surv. new south wales, vol. viii. pt. , , pp. - . lower cretaceous.--moore, c. quart. journ. geol. soc., vol. xxvi. , pp. - . etheridge, r. jnr. mem. r. soc. s. austr., vol. ii. pt. , , pp. , . upper cretaceous.--etheridge, r. jnr. geol. and pal. queensland, , p. . cainozoic.--mccoy, f. prod. pal. vict., dec. v. , pp. - . tate, r. trans. r. soc. s. austr., vol. iii. , pp. - . idem, ibid., vol. xxiii. , pp. - . hutton, f. w. trans. n.z. inst., vol. xxxvii. , pp. - (revn. tert. brach.). chapter x. fossil shell-fish (mollusca). =molluscan characters.--= the phylum or sub-kingdom mollusca is a group of soft-bodied animals (mollis, soft), which, although having no external skeleton, usually possess the protective covering of a shell. this shell is secreted from the outer skin or mantle, and is composed of carbonate of lime (calcareous) with a varying proportion of organic material. =hard parts.--= fossil molluscan remains consist practically of the shells, but the calcareous apertural lid (operculum) of some kinds is often preserved, as in _turbo_ and _hyolithes_; or the horny lids of others, as _bithynia_ of the european pleistocene "brick earths." the cuttle-fishes have hard, horny beaks and internal bones, and the latter are frequently found fossil in australia. =characters of pelecypoda.--= the class for first consideration is the important one of the bivalved mollusca, the _lamellibranchiata_ ("plate-gills") or _pelecypoda_ ("hatchet foot"). the shells are double, hinged dorsally and placed on either side of the animal, that is, they are left and right. the height is measured on a vertical line drawn from the beaks or umbones to the ventral margin. the length is the greatest distance between the margins parallel with a line drawn through the mouth and posterior adductor impression. the thickness is measured by a line at right angles to the line of height. the shell being placed mouth forward, the valves are thus left and right. the anterior is usually shorter, excepting in some cases, as in _donax_ and _nucula_. =hinge structure.--= in the absence of the animal, the character of the hinge-structure is very important. some are without teeth (edentulous). the oldest forms have been grouped as the "palaeoconcha," and it has been shown that here, although well-developed teeth were absent, the radial ribs of the surface and ventral areas were carried over to the dorsal margin and became a fixed character in the form of crenulations or primitive teeth. the taxodont type of hinge teeth shows alternating teeth and sockets, as in _nucula_. the schizodont type is seen in the heavy, variable teeth of _trigonia_ and _schizodus_. the isodont type of hingement is a modification of the taxodont, represented by two ridges originally divergent below the beak, and forming an interlocking series of two pairs of teeth and sockets as in _spondylus_; or where the primitive hinge disappears as in _pecten_, the divergent ridge-teeth (crura) may only partially develop. the dysodonts have a feeble hinge-structure derived from the external sculpture impinging on the hinge-line, as in _crenella_. the pantodonta are an ancient palaeozoic group which seems allied to the modern teleodont or long toothed shells, but the laterals may exceed a pair in a single group, as in _allodesma_. the diogenodonta have lateral and cardinal teeth upon a hinge-plate, but never more than two laterals and three cardinals in any one group, as in _crassatellites_. the cyclodonta have extremely arched teeth, which curve out from under the beaks, as in _cardium_. [illustration: =fig. --lower palaeozoic bivalves.= a--ambonychia macroptera, tate. cambrian. s. australia b--grammysia cuneiformis, eth. fil. silurian. victoria c--panenka gippslandica, mccoy sp. silurian. victoria d--nucula melbournensis, chapm. silurian. victoria e--nuculites maccoyianus. chapm. silurian. victoria f--palaeoneilo victoriae, chapm. silurian. victoria ] the teleodonts include the more highly developed types of hinge, with attenuated teeth and sockets. common shells of our coast, and from cainozoic beds, belonging to this group are _venus_, _mactra_ and _meretrix_. the asthenodonta are boring and burrowing molluscs that have lost the hinge dentition from disuse as _corbula_ and _pholas_. =cambrian bivalve.--= the earliest example of a bivalved shell in australian rocks is _ambonychia macroptera_ (fig. a), which occurs in the cambrian limestone of curramulka, s. australia. it is quite a small form, being less than a quarter of an inch in length. =ordovician bivalve.--= in the basal ordovician mudstone of heathcote, victoria, there is a bivalve which in some respects resembles a _modiolopsis_ (?_m. knowsleyensis_), but the exact relationship is still doubtful. =silurian bivalves.--= the silurian sandstones, mudstones, slates and limestones of australia and new zealand, unlike the older rocks just mentioned, contain a rich assemblage of bivalve fossils. in victoria the lower division or melbournian stage contains the following principal genera:--_orthonota_, _grammysia_, _leptodomus_, _edmondia_, _cardiola_, _ctenodonta_, _nuculites_, _nucula_, _palaeoneilo_, _conocardium_, _modiolopsis_ and _paracyclas_. the upper division or yeringian stage contains other species of similar genera to those in the melbournian, as _grammysia_, _palaeoneilo_ and _conocardium_; whilst _panenka_, _mytilarca_, _sphenotus_, _actinodesma_, _lunulicardium_, _actinopteria_ and cypricardinia are, so far as known, peculiar to this and a still higher stage. _cardiola_ is a widely distributed genus, occurring as well in tasmania; whilst in europe it is found both in bohemia and great britain. its time-range in the northern hemisphere is very extensive, being found in beds ranging from upper ordovician to devonian. _actinopteria_ is found also in new south wales and new zealand, and _pterinea_ and _actinodesma_ in new south wales. the molluscs with a taxodont hinge-line (beset with numerous little teeth and sockets) are quite plentiful in the australian silurian; such as _nucula_, a form common around melbourne (_n. melbournensis_ (fig. d)); _nuculites_, which has an internal radial buttress or clavicle separating the anterior muscle-scar from the shell-cavity, and which is found likewise in the melbourne shales (_n. maccoyianus_ (fig. e)); _ctenodonta_, represented in both the melbournian and yeringian stages (_c. portlocki_); and _palaeoneilo_, a handsome, subrostrate generic type with concentric lamellae or striae, commonest in the melbournian, but occasionally found in the younger stage (_p. victoriae_ fig. f, melbournian;--_p. raricostae_, yeringian). _conocardium_ is represented by two species in victoria (_c. bellulum_ and _c. costatum_); whilst in new south wales _c. davidis_ is found at oakey creek. in new zealand _actinopteria_ and _pterinea_ occur in the wangapeka series (silurian). =devonian bivalves.--= the compact limestone and some shales of middle devonian age in the n.e. gippsland area in victoria, contain several as yet undescribed species belonging to the genera _sphenotus_, _actinodesma_ and _paracyclas_. [illustration: =fig. --palaeozoic bivalves.= a--mytilarca acutirostris, chapm. silurian. victoria b--modiolopsis melbournensis, chapm. silurian. victoria c--goniophora australis, chapm. silurian. victoria d--paracyclas siluricus, chapm. silurian. victoria e--actinopteria australis, dun. devonian. new south wales f--lyriopecten gracilis, dun. devonian. new south wales ] the genera _paracyclas_, _aviculopecten_ and _pterinea_ have been recorded from new south wales, chiefly from the yass district. the derived boulders found in the upper cretaceous beds forming the opal-fields at white cliffs, new south wales, have been determined as of devonian age. they contain, amongst other genera, examples of _actinopteria_ (_a. australis_), _lyriopecten_ (_l. gracilis_) (fig. f), and _leptodesma_ (_l. inflatum_ and _l. obesum_). [illustration: =fig. --carbopermian bivalves.= a--stutchburia farleyensis, eth. fil. carbopermian. n.s. wales b--deltopecten limaeformis, morris sp. carbopermian. n.s. wales c--aviculopecten sprenti, johnston. carbopermian. n.s. wales d--chaenomya etheridgei, de kon. carbopermian. n.s. wales e--pachydomus globosus j. de c. sow. carbopermian. n.s. wales ] =carbopermian bivalves.--= one of the most prolific palaeozoic series for bivalved mollusca is the carbopermian. to select from the numerous genera and species we may mention _stutchburia farleyensis_ (fig. a) and _edmondia nobilissima_ from farley, new south wales; and _deltopecten limaeformis_ (fig. b), found in the lower marine series at ravensfield, new south wales, and in the upper marine series at burragorang and pokolbin in the same state, in queensland at the mount britton gold-field, and in maria id., tasmania. _deltopecten fittoni_ occurs in both series in new south wales, and in the upper marine series associated with "tasmanite shale" in tasmania. _aviculopecten squamuliferus_ is a handsome species found alike in tasmania and new south wales; whilst _a. tenuicollis_ is common to w. australia and new south wales. other characteristic bivalves of the carbopermian of new south wales are _chaenomya etheridgei_ (fig. d) and _pachydomus globosus_ (fig. e). the gigantic _eurydesma cordatum_ is especially characteristic of the new south wales lower marine series, and is also found in tasmania. all three species are found in queensland. =triassic bivalves.--= the triassic rocks of new south wales were accumulated under either terrestrial, lacustrine, or brackish (estuarine) conditions. hence the only bivalved mollusca found are referred to the freshwater genera _unio_ (_u. dunstani_) and _unionella_ (_u. bowralensis_ and _u. carnei_ (fig. a)). the latter genus differs from unio in the structure of the adductor muscle-impressions. [illustration: =fig. --lower mesozoic bivalves.= a--unionella carnei, eth. fil. triassic. new south wales b--mytilus problematicus, zittel. triassic. new zealand c--monotis salinaria, zittel. triassic. new zealand d--trigonia moorei, lycett. jurassic. w. australia e--astarte cliftoni, moore. jurassic. w. australia ] the queensland trias (burrum formation) contains a solitary species of bivalved mollusca, _corbicula burrumensis_. this genus is generally found associated with freshwater or brackish conditions. in new zealand marine triassic beds occur, containing, amongst other genera, a species of _leda_. in the succeeding wairoa series the interesting fossil, _daonella lommeli_ occurs. this shell is typical of the norian (upper trias) of the southern tyrol. above the _daonella_ bed occurs the _trigonia_ bed, with that genus and _edmondia_. in the next younger stage, the otapiri series, near nelson, there are fine-grained sandstones packed full of the remains of _mytilus problematicus_ (fig. b) and _monotis salinaria_ (fig. c), the latter also a norian fossil. =jurassic bivalves.--= jurassic bivalved molluscs are plentiful in the w. australian limestones, as at greenough river. amongst others may be mentioned _cucullaea semistriata_, _ostrea_, _gryphaea_, _trigonia moorei_ (fig. d), _pecten cinctus_, _ctenostreon pectiniforme_ and _astarte cliftoni_ (fig. e). several of the species found are identical with european jurassic fossils. jurassic strata in victoria, being of a freshwater and lacustrine nature, yield only species of _unio_, as _u. dacombei_, and _u. stirlingi_. the jurassic beds of s. australia contain a species of _unio_ named _u. eyrensis_. in the same strata which contains this shell, plant remains are found, as _cladophlebis_ and _thinnfeldia_, two well-known types of jurassic ferns. =lower cretaceous bivalves.--= in queensland the lower cretaceous limestones and marls contain a large assemblage of bivalves, the more important of which are _nucula truncata_ (fig. a), _maccoyella reflecta_ (fig. b), _m. barkleyi_, _pecten socialis_ and _fissilunula clarkei_ (fig. c), from wollumbilla; and _inoceramus pernoides_, _i. carsoni_ and _aucella hughendenensis_ from the flinders river (the latter also from new south wales). in the lake eyre district of s. australia we find _maccoyella barkleyi_, which also occurs in queensland and new south wales (at white cliffs), _trigonia cinctuta_, _mytilus rugocostatus_ and _modiola eyrensis_. the handsome bivalve, _pleuromya plana_ occurs near broome in w. australia. [illustration: =fig. --cretaceous bivalves.= a--nucula truncata, moore. l. cretaceous. south australia b--maccoyella reflecta, moore sp. up. and l. cretaceous. q'land. c--fissilunula clarkei, moore sp. up. and l. cretaceous. q'land. d--inoceramus carsoni, mccoy. l. cretaceous. queensland e--cyrenopsis opallites, eth. fil. up. cretaceous. new south wales f--conchothyra parasitica, hutton. cretaceous. new zealand ] =upper cretaceous bivalves.--= the upper cretaceous or desert sandstone at maryborough, queensland, has yielded amongst others, the following shells:--(_nucula gigantea_, _maccoyella reflecta_ also found in the lower cretaceous of queensland, new south wales and s. australia), and _fissilunula clarkei_ (also found in the l. cretaceous of new south wales, queensland and s. australia). some of these beds, however, which were hitherto believed to belong to the upper and lower series respectively may yet prove to be on one horizon--the lower cretaceous. _cyrenopsis opallites_ (fig. e) of white cliffs, new south wales, appears to be a truly restricted upper cretaceous species. the cretaceous of new zealand (amuri system) contains _trigonia sulcata_, _inoceramus_ sp. and the curious, contorted shell, _conchothyra parasitica_ (fig. f) which is related to _pugnellus_, a form usually considered as a sub-genus of _strombus_. from papua an _inoceramus_ has been recorded from probable cretaceous beds. =cainozoic bivalves.--= in victoria, south australia, and the n.w. of tasmania, as well as in new zealand, cainozoic marine beds are well developed, and contain an extensive bivalved molluscan fauna. of these fossils only a few common and striking examples can here be noticed, on account of the limits of the present work. the commonest genera are:--_ostrea_, _placunanomia_, _dimya_, _spondylus_, _lima_, _pecten_, _arca_, _barbatia_, _plagiarca_, _cucullaea_, _glycimeris_, _limopsis_, _nucula_, _leda_, _trigonia_, _cardita_, _cuna_, _crassatellites_, _cardium_, _protocardium_, _chama_, _meretrix_, _venus_ (_chione_), _dosinea_, _gari_, _mactra_, _corbula_, _lucina_, _tellina_, _semele_ and _myodora_. [illustration: =fig. --cainozoic bivalves.= a--dimya dissimilis, tate. balcombian. victoria b--spondylus pseudoradula, mccoy. balcombian. victoria c--pecten polymorphoides, zittel. janjukian. south australia d--leda vagans, tate. janjukian. south australia e--modiola praerupta, pritchard. balcombian. victoria ] =persistent species.--= to mention a few species of persistent range, from balcombian to kalimnan, we may cite the following from the cainozoic of southern australia:--_dimya dissimilis_ (fig. a), _spondylus pseudoradula_ (fig. b), _lima (limatula) jeffreysiana_, _pecten polymorphoides_ (found also in the oamaru series, new zealand) (fig. c), _amusium zitteli_ (found also in both the waimangaroa and oamaru series of new zealand), _barbatia celleporacea_, _cucullaea corioensis_, _limopsis maccoyi_, _nucula tenisoni_, _leda vagans_ (fig. d), _corbula ephamilla_ and _myodora tenuilirata_. =balcombian bivalves.--= on the other hand, many species have a restricted range, and these are invaluable for purposes of stratigraphical correlation. for example, in the balcombian we have _modiola praerupta_ (fig. e), _modiolaria balcombei_, _cuna regularis_, _cardium cuculloides_, _cryptodon mactraeformis_, _verticordia pectinata_ and _v. excavata_. [illustration: =fig. --cainozoic bivalves.= a--modiola pueblensis, pritchard. janjukian. victoria b--cardita tasmanica, tate. janjukian. tasmania c--lucina planatella, tate. janjukian. tasmania d--ostrea manubriata, tate. kalimnan. victoria e--limopsis beaumariensis, chap. kalimnan. victoria f--venus (chione) subroborata, tate sp. kalimnan. victoria ] =janjukian bivalves.--= in the janjukian series restricted forms of bivalves are exceptionally numerous, amongst them being:--_dimya sigillata_, _plicatula ramulosa_, _lima polynema_, _pecten praecursor_, _p. eyrei_, _p. gambierensis_, _pinna cordata_, _modiola pueblensis_ (fig. a), _arca dissimilis_, _limopsis multiradiata_, _l. insolita_, _leda leptorhyncha_, _l. crebrecostata_, _cardita maudensis_, _c. tasmanica_ (fig. b), _cuna radiata_, _lepton crassum_, _cardium pseudomagnum_, _venus (chione) multitaeniata_, _solenocurtus legrandi_, _lucina planatella_ (fig. c), _tellina porrecta_ and _myodora lamellata_. in papua a _pecten_ (_p. novaeguineae_) has been recorded from the ? lower pliocene of yule island. =kalimnan bivalves.--= the kalimnan beds contain the following restricted or upward ranging species:--_ostrea arenicola_, _o. manubriata_ (fig. d), _pecten antiaustralis_ (also in the werrikooian series), _perna percrassa_, _mytilus hamiltonensis_, _glycimeris halli_, _limopsis beaumariensis_ (also werrikooian) (fig. e), _leda crassa_ (also living), _trigonia howitti_, _cardita solida_, _c. calva_ (also living), _erycina micans_, _meretrix paucirugata_, _sunetta gibberula_, _venus (chione) subroborata_ (fig. f), _donax depressa_, _corbula scaphoides_ (also living), _barnea tiara_, _lucina affinis_, _tellina albinelloides_ and _myodora corrugata_. =werrikooian bivalves.--= the next stage, the werrikooian (upper pliocene), contains a large percentage of living species, as _ostrea angasi_, _placunanomia ione_ (ranging down into janjukian), _glycimeris radians_, _leda crassa_ (also a common kalimnan fossil), various species of _venus (chione)_, as _v. strigosa_ and _v. placida_, and _barnea australasiae_. =pleistocene bivalves.--= the bivalved shells of the pleistocene are similar to those now found living round the australian coast, as _pecten asperrimus_, _mytilus latus_, _leda crassa_, _soletellina biradiata_ and _spisula parva_. pleistocene shells of bivalved genera occur in the coastal hills of papua, including the following:--_cultellus_, _corbula_, _mactra_, _tellina_, _venus (chione)_, _dione_, _dosinea_, _leda_ and _arca_. the _scaphopods_ ("digger foot") or the "elephant-tusk shells" are adapted, by their well-developed foot, to burrow into the mud and sand. [illustration: =fig. --fossil scaphopods and chitons.= a--dentalium huttoni, bather. jurassic. new zealand b--dentalium mantelli, zittel. cainozoic. victoria c--chelodes calceoloides, eth. fil. silurian. new south wales d--ischnochiton granulosus, ashby and torr sp. cainozoic (balc). victoria e--cryptoplax pritchardi, hall. cainozoic (kalimnan). victoria ] =devonian scaphopods.--= this group of mollusca makes its first appearance in australasian sediments in the middle devonian (murrumbidgee beds) of new south wales, represented by _dentalium tenuissimum_. =jurassic scaphopods.--= in the jurassic strata of the mataura series of new zealand, _dentalium huttoni_ (fig. a) occurs at the kowhai river and wilberforce. =cretaceous scaphopods.--= _dentalium wollumbillensis_ occurs in the drab and dark-coloured limestones of the lower cretaceous of the lake eyre basin in s. australia, and the same species is also found in the lower cretaceous (rolling downs formation) of wollumbilla, queensland. =cainozoic scaphopods.--= the cainozoic beds both of new zealand and southern australia yield many species of _dentalium_, the commonest and most widely distributed being the longitudinally ribbed _d. mantelli_ (fig. b), which ranges from the balcombian to the werrikooian stages in australia, and is also typical of the oamaru series in new zealand, where it is accompanied by the ponderous species, _d. giganteum_, which attained a length of over six inches. another form common in our cainozoics is the smooth-shelled _d. subfissura_; this also has a wide range, namely balcombian to kalimnan. =palaeozoic chitons.--= the _polyplacophora_ or chitons ("mail-shells"), first appeared in the ordovician. in australia _chelodes calceoloides_ (fig. c) is found in the silurian of derrengullen creek, yass, new south wales; and another species of the genus is found in beds of the same age at lilydale, victoria. between that period and the cainozoic or tertiary there is a gap in their history in australia. =cainozoic chitons.--= _ischnochiton granulosus_ (fig. d) is a balcombian species of the modern type of "mail-shell," occurring not infrequently in the clays of balcombe's bay, port phillip, victoria. _cryptoplax pritchardi_ (fig. e) is a curious form belonging to the attenuated, worm-like group of the cryptoplacidae, until lately unknown in the fossil state; it is found in the kalimnan series near hamilton, victoria. several other genera of the chitons are found fossil in the australian cainozoics which still live on our coasts, as _lorica_, _plaxiphora_ and _chiton_. the first-named genus is represented fossil by _lorica duniana_ from the _turritella_ bed (janjukian) of table cape, tasmania. =characters of gasteropoda.--= the _gasteropoda_ ("belly-foot") or univalve shells possess a muscular foot placed beneath the stomach and viscera. in the heteropoda this foot is modified as a vertical fin, and in the pteropoda as two wing-like swimming membranes close to the head. the mantle lobe is elevated along the back like a hood, and its surfaces and edges secrete the shell which contains the animal. the shell is typically a cone (example, _patella_ or limpet) which is often spirally coiled either in a plane (ex. _planorbis_), conically turbinoid (ex. _trochus_), or turreted (ex. _turritella_). the body and shell are attached by muscles, the spiral forms being attached to the columella or axial pillar, and the bowl-shaped forms to the inner surface of the shell. gasteropod shells are normally right-handed (dextral), but a few genera as _clausilia_, _bulinus_ and _physa_, are left-handed (sinistral). the height or length of the shell is measured from the apex to the lower margin of the mouth. in coiled shells we may regard them as a more or less elongated cone wound round a central pillar, the columella, or around a central tube. a turn or coil of the shell is a whorl, and together, with the exception of the last, form the spire. the line between two adjacent whorls is the suture. when the columella is solid the shell is said to be imperforate, and when a central tube is left by the imperfect fusion of the whorls, it is perforate. the opening of the tubular columella is termed the umbilicus, and this is sometimes contracted by the encroachment of shell matter termed the callus. the aperture is entire when the rim is uninterrupted; and channelled when there is a basal notch, where the siphon which conducts water to the gills is lodged. as a rule the large heavy gasteropods inhabit shallow water. the following living genera are characteristic of rocky shore-lines; _risella_, _buccinum_, _purpura_ and _patella_. genera typical of sandy shores are _nassa_, _natica_, _cypraea_, _turritella_ and _scala_. =cambrian gasteropods.--= from the cambrian of south australia prof. tate described some minute gasteropods which he referred to the genera _stenotheca_ (_s. rugosa_, var. _paupera_), _ophileta (o. subangulata)_ (fig. a), and _platyceras (p. etheridgei)_. in these beds at curramulka the following pteropods were found by the same authority, viz., _salterella planoconvexa_, _hyolithes communis_ (fig. c) and _h. conularioides_. the cambrian limestone of the kimberley district, w. australia, contains the characteristic pteropod _salterella hardmani_ (fig. b). the shell is a conical tube, straight or slightly curved, and measuring scarcely an inch in length. [illustration: =fig. --lower palaeozoic gasteropoda.= a--ophileta subangulata, tate. cambrian. south australia b--salterella hardmani, foord. cambrian. west australia c--hyolithes communis, billings. cambrian. south australia d--scenella tenuistriata, chapm. cambrian. victoria e--raphistoma browni, eth. fil. ordovician. south australia f--helicotoma johnstoni, eth. fil. silurian. tasmania ] the upper cambrian of the mersey river district in tasmania has afforded some doubtful examples of the genus _ophileta_. in the upper cambrian limestones of the dolodrook valley, near mt. wellington, victoria, a minute limpet shaped gasteropod occurs, named _scenella tenuistriata_ (fig. d). =ordovician gasteropods.--= ordovician limestones with fossil shells occur in the leigh's creek district in south australia, and also at tempe downs and petermann and laurie's creeks, w. of alice springs. the euomphaloid shell _ophileta gilesi_ was described from laurie's creek, and _eunema larapinta_ from the tempe downs. a pleurotomarid, _raphistoma browni_ (fig. ) occurs near leigh's creek, and at laurie's and petermann creeks. a pteropod, _hyolithes leptus_, has been described from the lower ordovician of coole barghurk creek, near meredith, victoria. =silurian gasteropods.--= the silurian gasteropods are fairly well represented, especially in the upper stage, and are widely distributed throughout the australian fossiliferous localities. moreover, some of the species are identical with those found as far off as north america and europe. in victoria the shales and sandstones of the lower stage (melbournian) contain the genera _bellerophon_, _cyrtolites_ and _loxonema_. the pteropoda include _tentaculites_, _coleolus_, _hyolithes_ and _conularia_ (_c. sowerbii_ (fig. f), a species also found in great britain). the victorian limestones and mudstones of the upper stage (yeringian) are somewhat rich in gasteropods, such genera occurring as _pleurotomaria_, _phanerotrema_ (with cancellated shell and large slit-band), _murchisonia_, _gyrodoma_, _bellerophon_, _trematonotus_ (a spiral shell with a large trumpet-shaped mouth and a dorsal row of perforations in place of a slit-band), _euomphalus_, _cyclonema_, _trochus (scalaetrochus)_, _niso (vetotuba)_, _loxonema_, _platyceras_ and _capulus_. the section pteropoda contains _tentaculites_, _hyolithes_ and _conularia_. [illustration: =fig. --silurian gasteropoda.= a--hyolithes spryi, chapm. silurian (melb.) victoria b--gyrodoma etheridgei, cressw. sp. silurian (yeringian). vict. c--bellerophon cresswelli. eth. fil. silurian (yeringian). victoria d--euomphalus northi, eth. fil. sp. silurian (yeringian). victoria e--trochonema montgomerii. eth. fil. sp. silurian. tasmania f--conularia sowerbii, defr. silurian (yeringian). victoria ] in the silurian of new south wales the chief gasteropod genera are _bellerophon (b. jukesi)_, _euomphalus_, _omphalotrochus_, and _conularia (c. sowerbii.)_. in tasmania are found _raphistoma_, _murchisonia_, _bellerophon_, _helicotoma_, _trochonema_ and _tentaculites_. =devonian gasteropods.--= the derived boulders of the white cliffs opal field have been referred to the devonian system, but of this there is some doubt, as the gasteropods noted from these boulders closely resemble those of the silurian fauna: they are _murchisonia euomphalus_ (_e. culleni_), and _loxonema_. the genus _murchisonia_ has also been recorded from the baton river, new zealand (wangepeka series) by mackay. the middle devonian gasteropod fauna in victoria, as found in the buchan and bindi limestones, comprises _murchisonia_, _trochus_, and _platyceras_. [illustration: =fig. --upper palaeozoic gasteropoda.= a--gosseletina australis, eth. fil. sp. carboniferous. n.s. wales b--yvania konincki, eth. fil. carboniferous. n.s. wales c--loxonema babbindoonensis, eth. fil. carboniferous. n.s. wales d--pleurotomaria (ptychomphalina) morrisiana, mccoy. carbopermian. n.s. wales e--platyschisma oculum, sow. sp. carbopermian. n.s. wales f--murchisonia carinata, eth. carbopermian. queensland ] in new south wales the best known genera are _pleurotomaria_, _murchisonia_, _bellerophon_, _euomphalus_ and _loxonema_. the two latter genera have also been obtained at barker gorge, western australia. =carboniferous gasteropods.--= carboniferous gasteropoda have been found in new south wales, belonging to the genera _gosseletina_ (_g. australis_) (fig. a) and _yvania_ (_y. konincki_) (fig. b), both of which have their countertypes in the carboniferous of belgium. _y. konincki_ is also found in the carbopermian (gympie beds) of rockhampton, queensland, while _y. levellii_ is found in the carbopermian of western australia. =carbopermian gasteropods.--= the carbopermian gasteropods of new south wales are _pleurotomaria_ (_mourlonia_), _keeneia platyschismoides_, _murchisonia_, _euomphalus_, _platyschisma_ (_p. oculum_) (fig. e), _loxonema_ and _macrocheilus_. examples of the genus _conularia_ are sometimes found, probably attaining a length, when complete, of centimetres. in tasmania we find _conularia tasmanica_, a handsome pteropod, also of large dimensions. _platyschisma_, _pleurotomaria_ (_mourlonia_), _bellerophon_ and _porcellia_ are amongst the carbopermian gasteropods of queensland. in western australia _pleurotomaria_ (_mourlonia_), _bellerophon_, _euomphalus_, _euphemus_, _platyceras_, and _loxonema_ occur in the carbopermian. =jurassic gasteropods.--= jurassic gasteropods are found sparingly in the limestone of the geraldton district and other localities in western australia. the more important of these are _pleurotomaria_ (_p. greenoughiensis_), _turbo_ (_t. australis_) (fig. a) and _rissoina_ (_r. australis_) (fig. b). [illustration: =fig. --mesozoic gasteropoda.= a--turbo australis, moore. jurassic. west australia b--rissoina australis, moore. jurassic. west australia c--natica ornatissima, moore. cretaceous. queensland d--pseudamaura variabilis, moore sp. cretaceous. queensland e--rostellaria waiparensis, hector.--cretaceous. new zealand ] =cretaceous gasteropods.--= the queensland gasteropod fauna comprises _cinulia_ a typical cretaceous genus, _actaeon_ and _natica_. these occur in the lower cretaceous or rolling downs formation. _cinulia_ is also found in south australia at lake eyre with _natica_ (_n. ornatissima_) (fig. c). _pseudamaura variabilis_ (fig. d) is found in new south wales, queensland and south australia; whilst _anchura wilkinsoni_ occurs in queensland and south australia. in new zealand the waipara greensands (cretaceous) contain a species of _rostellaria_ (_r. waiparensis_) (fig. e). =cainozoic gasteropods.--= cainozoic gasteropods are exceedingly abundant in beds of that system in australasia. the cainozoic marine fauna in australia is practically restricted to the states of victoria, south australia, and tasmania; whilst new zealand has many species in common with australia. =genera.--= the commonest genera of the marine cainozoic or tertiary deposits are:--_haliotis_, _fissurellidea_, _emarginula_, _subemarginula_, _astralium_, _liotia_, _gibbula_, _eulima_, _niso_, _odostomia_, _scala_, _solarium_, _crepidula_, _calyptraea_, _natica_, _rissoa_, _turritella_, _siliquaria_, _cerithium_, _newtoniella_, _tylospira_, _cypraea_, _trivia_, _morio_, _semicassis_, _lotorium_, _murex_, _typhis_, _columbella_, _phos_, _nassa_, _siphonalia_, _euthria_ (_dennantia_), _fusus_, _columbarium_, _fasciolaria_, _latirus_, _marginella_, _mitra_, _volutilithes_, _voluta_, _harpa_, _ancilla_, _cancellaria_, _terebra_, _pleurotoma_, _drillia_, _conus_, _bullinella_ and _vaginella_. =persistent species.--= amongst the cainozoic gasteropoda of southern australia which have a persistent range through balcombian to kalimnan times, we find:--_niso psila_, _crepidula unguiformis_ (also werrikooian and recent), _natica perspectiva_, _n. hamiltonensis_, _turritella murrayana_, _cerithium apheles_, _cypraea leptorhyncha_, _lotorium gibbum_, _volutilithes antiscalaris_ (also in werrikooian), _marginella propinqua_, _ancilla pseudaustralis_, _conus ligatus_ and _bullinella exigua_. =balcombian gasteropods.--= species restricted to the balcombian stage include _scala dolicho_, _seguenzia radialis_, _dissocheilus eburneus_, _trivia erugata_, _cypraea ampullacea_ (fig. a), _c. gastroplax_, _colubraria leptoskeles_, _murex didymus_ (fig. b), _eburnopsis aulacoessa_ (fig. c), _fasciolaria concinna_, _mitra uniplica_, _harpa abbreviata_, _ancilla lanceolata_, _cancellaria calvulata_ (fig. d), _buchozia oblongula_, _pleurotoma optata_, _terebra leptospira_ and _vaginella eligmostoma_ (fig. e), (also found at gellibrand river). [illustration: =fig. --cainozoic gasteropoda.= a--cypraea ampullacea, tate. cainozoic (balc.) victoria b--murex didymus, tate. cainozoic (balc.) victoria c--eburnopsis aulacoessa, tate. cainozoic (balc.) victoria d--cancellaria calvulata, tate. cainozoic (balc.) victoria e--vaginella eligmostoma, tate. cainozoic (balc.) victoria ] [illustration: =fig. --cainozoic gasteropoda.= a--eutrochus fontinalis, pritchard. cainozoic (janjukian). vict. b--morio wilsoni, tate. cainozoic (janjukian). victoria c--scala lampra, tate sp. cainozoic (janjukian). south australia d--natica gibbosa, hutton. cainozoic (janjukian). south australia e--volutilithes anticingulatus, mccoy sp. cainozoic (janjukian). victoria f--struthiolaria sulcata, hutton. cainozoic (awatere series). new zealand ] =janjukian gasteropods.--= species of gasteropods restricted to the janjukian stage include:--_pleurotomaria tertiaria_, _haliotis mooraboolensis_, _liotia lamellosa_, _thalotia alternata_, _eutrochus fontinalis_ (fig. a), _astralium hudsonianum_, _turbo atkinsoni_, _odostomia polita_, _scala lampra_ (fig. c), _natica gibbosa_ (fig. d) (also found in the pareora series of the oamaru system and in the wanganui beds of new zealand), _calyptraea subtabulata_, _turritella aldingae_, _cerithiopsis mulderi_, _cerithium flemingtonense_, _cypraea platyrhyncha_, _c. consobrina_, _morio wilsoni_ (fig. b), _lotorium abbotti_, _murex otwayensis_, _eburnopsis tesselatus_, _tudicla costata_, _latirus semiundulatus_, _fusus meredithae_, _columbarium spiniferum_, _voluta pueblensis_, _v. heptagonalis_, _v. macroptera_ (also recorded from hall's sound, papua) (fig. e), _volutilithes anticingulatus_ (also from papua), _harpa clathrata_, _bela woodsi_, _bathytoma paracantha_ and _volvulella inflatior_. _dolium costatum_, allied to the "fig-shell" has been noted from the cainozoic clays (? lower pliocene), yule island, papua. [illustration: =fig. --late cainozoic and pleistocene gasteropoda= a--bankivia howitti, pritchard. cainozoic (kal.) victoria b--eglisia triplicata, tate sp. cainozoic (kal.) victoria c--voluta masoni, tate. cainozoic (kal.) victoria d--ancilla papillata. tate sp. cainozoic (kal.) victoria e--terebra geniculata, tate. cainozoic (kal.) victoria f--helix simsoniana, johnston. pleistocene. tasmania ] =kalimnan gasteropods.--= species of gasteropods restricted to the kalimnan stage, or only passing upwards include:--_bankivia howitti_ (fig. a), _liopyrga quadricingulata_, _calyptraea corrugata_, _natica subvarians_, _turritella pagodula_, _eglisia triplicata_ (fig. b), _tylospira clathrata_, _cypraea jonesiana_, _lotorium ovoideum_, _sistrum subreticulatum_, _voluta masoni_ (fig. c), _ancilla papillata_ (fig. d), _cancellaria wannonensis_, _drillia wanganuiensis_ (also in the petane series of new zealand), _terebra catenifera_, _t. geniculata_ (fig. e) and _ringicula tatei_. =new zealand cainozoic gasteropods.--= characteristic gasteropoda of the oamaru series in new zealand are _pleurotomaria tertiaria_ (also in the australian janjukian), _scala lyrata_, _natica darwinii_, _turritella cavershamensis_, _ancilla hebera_ (also in the australian balcombian and janjukian) and _pleurotoma hamiltoni_. gasteropods of the awatere series in new zealand are _natica ovata_, _struthiolaria sulcata_ (fig. f), and _scaphella corrugata_ (found also in the oamaru series). the putiki beds of the petane series in new zealand contain _trophon expansus_, _pisania drewi_ and _pleurotoma wanganuiensis_. =werrikooian gasteropods.--= the marine gasteropods of the werrikooian of southern australia, as found at limestone creek, glenelg river, western victoria, and the moorabool viaduct near geelong, are nearly all living at the present time, with the exception of a few older cainozoic species. amongst these latter are _conus ralphi_, _pleurotoma murndaliana_, _volutilithes antiscalaris_ and _columbarium craspedotum_. =pleistocene gasteropoda.--= the pleistocene land mollusca, and especially the gasteropods of australia, present some striking points of interest, for whilst most of the species are still living, some appear to be extinct. the travertine deposits of geilston, near hobart, tasmania contain _helix geilstonensis_ and _h. stanleyana_, the latter still living. the calcareous _helix_ sandstone of the islands in bass strait are largely composed of shells of that genus and generally represent consolidated sand-dunes which have undergone a certain amount of elevation. one of the prevalent species is _helix simsoniana_ (fig. f), a handsome keeled form, somewhat related to the living _h. launcestonensis_. it is found in some abundance in the kent's group and in the adjacent islands. the large ovoid land-shells, _panda atomata_, although still existing, are found associated with extinct marsupials, as _thylacoleo_, in the stalagmitic floor of the buchan caves, gippsland. the _diprotodon_-breccias of queensland have afforded several species of _helix_ and other land-shells, as well as the brackish-water genus _melania_. the raised beaches of queensland, new south wales, victoria, and tasmania all contain species of land and freshwater shells identical with those now found living in the same localities. the raised beaches of new zealand contain numerous marine shells all having living representatives. some of these elevated beaches occur as high as feet above sea-level at taranaki, and at feet near cape palliser in cook strait. many species of pleistocene mollusca identical with those now living in torres strait, the china sea and the philippine islands are found in papua. they occur in the greenish sandy clay of the hills near the present coast line and comprise the following genera of gasteropods:--_ranella_, _nassa_, _mitra_, _oliva_, _terebra_, _conus_, _strombus_, _bulla_ and _atys_. =characters of cephalopoda.--= the highest class of the mollusca is the _cephalopoda_ ("head-feet"). in these shell-fish the extremity of the body or foot is modified, and furnished with eyes, a funnel and tentacles. it has also strong horny beaks or jaws which make it a formidable enemy to the surrounding life in the sea. in the chambered forms of this group the animal partitions off its shell at regular intervals, like the pearly nautilus and the ammonite, inhabiting only the last chamber cavity, but still communicating with the earlier series by a continuous spiral tube (siphuncle). in some forms like the living squid and the extinct belemnite, the shell is internal and either spoon-shaped, or dart-shaped, that is, subcylindrical and pointed. =characters of cephalopod shells.--nautiloidea.--= in geological times the nautiloid forms were the first to appear (in the ordovician), and they were either straight shells, as _orthoceras_, or only slightly curved, as _cyrtoceras_. later on they became more closely coiled, and as they were thus less likely to be damaged, they gradually replaced the straight forms. the ammonites have the siphuncle close to the outside of the shell, whilst in the nautilus it is more or less median. the sutures or edges of the septa in _nautilus_ and its allies are curved or wavy, but not so sharply flexed or foliaceous as in _ammonites_. the nautiloidea range from the ordovician and are still found living. =ammonoidea.--= the ammonoidea appear in devonian times and die out in the cretaceous. they were very abundant in jurassic times, especially in europe. =belemnoidea.--= the belemnoidea, ranging from the trias to eocene, comprise the extinct _belemnites_, the interesting genus _spirulirostra_ of miocene times, and the living _spirula_. =sepioidea.--= the sepioidea or true cuttle-fishes ("pen-and-ink fish") range from the trias to the present day. =octopoda.--= the octopoda, with _octopus_ and _argonauta_ (the paper "nautilus") are present-day modifications. the male of the latter is without a shell, the female only being provided with a delicate boat-shaped shell secreted by the mantle and the two fin-like expansions of the dorsal arms. =ordovician cephalopods.--= the ordovician cephalopods of australasia are not numerous, and are, so far as known, practically restricted to the limestones of the larapintine series at laurie's creek and tempe downs, in central south australia. amongst them may be mentioned _endoceras warburtoni_ (fig. a), (a straight form in which the siphuncle is partially filled with organic deposits); _orthoceras gossei_; _o. ibiciforme_; _trochoceras reticostatum_ (a coiled form); and _actinoceras tatei_ (a genus characterised by swollen siphuncular beads between the septa). [illustration: =fig. --palaeozoic cephalopoda.= a--endoceras warburtoni, eth. fil. ordovician. south australia b--orthoceras lineare, münster sp. silurian (yer.) victoria c--cycloceras ibex, sow. sp. silurian (melb.) victoria d--phragmoceras subtrigorium, mccoy. mid devonian. victoria e--gastrioceras jacksoni, eth. fil. carbopermian. w. australia f--agathiceras micromphalum, morris sp. carbopermian. n.s.w. ] =silurian cephalopods.--= silurian cephalopods are more generally distributed, and in victoria constitute an important factor in the molluscan fauna of that system. _orthoceras_ and _cycloceras_ are the best known genera, represented by _orthoceras capillosum_, found near kilmore, victoria; _o. lineare_ (fig. b), from the upper yarra; _cycloceras bullatum_, from the melbournian of collingwood and whittlesea; and _c. ibex_ (fig. c) from south yarra and flemington, in both melbournian shale and sandstone. the latter species occurs also at rock flat greek, new south wales. other victorian species are _kionoceras striatopunctatum_, a well-known european fossil with a reticulated and beaded ornament, found near warburton and at mcmahon's creek, upper yarra. _orthoceras_ is also recorded from tasmania and from the wangapeka beds of baton river, new zealand. _cyclolituites_, a partially coiled nautilian is recorded from bowning, near yass, new south wales; whilst the closely related _lituites_ is noted from the silurian of tasmania. =devonian cephalopods.--= the only genus of cephalopoda at present recorded from the devonian of victoria is _phragmoceras_ (_p. subtrigonum_) (fig. d), which occurs in the middle devonian limestone of buchan, e. gippsland. from beds of similar age in new south wales _orthoceras_, _cyrtoceras_ and _goniatites_ have been noted; whilst the latter genus also occurs near kimberley, western australia. in queensland _gyroceras philpi_ is a characteristic shell, found in the fanning and reid gap limestones of the burdekin formation (middle devonian). =carbopermian cephalopods.--= the carbopermian rocks of new south wales have yielded _orthoceras striatum_, _cameroceras_, _nautilus_ and _agathiceras micromphalum_ (fig. f). in queensland the gympie formation contains _orthoceras_, _gyroceras_, _nautilus_, _agathiceras micromphalum_ and _a. planorbiforme_. in western australia the kimberley rocks contain _orthoceras_, _glyphioceras sphaericum_ and _agathiceras micromphalum_; whilst the largest known australian goniatite, _gastrioceras jacksoni_ (fig. e) is found in the irwin river district. _actinoceras hardmani_ is an interesting fossil from the carbopermian of lennard river, n.w. australia. in tasmania the genera _orthoceras_ and _goniatites_ have been recorded from beds of similar age. =triassic cephalopods.--= for triassic cephalopoda we look to new zealand, where, in the mount potts _spiriferina_ beds of the kaihiku series a species of _orthoceras_ has been recorded. the wairoa series next in succession contains _orthoceras_ and an ammonite. =jurassic cephalopods.--= [illustration: =fig. --mesozoic and cainozoic cephalopoda.= a--perisphinctes championensis, crick. jurassic. west australia b--nautilus hendersoni, eth. fil. l. cretaceous. queensland c--haploceras daintreei, eth. sp. l. cretaceous. queensland d--crioceras australe, moore. l. cretaceous. queensland e--aturia australis, mccoy. cainozoic. victoria f--spirulirostra curta, tate. cainozoic (janjukian). victoria ] the jurassic of western australia yields a rich cephalopod fauna, from which may be selected as typical examples the _nautilus_, _n. perornatus_ and the following ammonites: _dorsetensia clarkei_; _normanites australis_; and _perisphinctes championensis_ (fig. a). these all occur in the greenough river district, and at several other jurassic localities in western australia. the jurassic system of new zealand (putataka series) contains _ammonites aucklandicus_ and _belemnites aucklandicus_, both from the upper marine horizon of that series. upper jurassic ammonites belonging to the genera _macrocephalites_ (_m._ cf. _calloviensis_) and _erymnoceras_ (_e._ cf. _coronatum_) have been recorded from papua. =lower cretaceous cephalopods.--= remains of cephalopoda are fairly abundant in the lower cretaceous of australasia. from amongst them may be selected the following--_nautilus hendersoni_ (fig. b) (q.); _haploceras daintreei_ (fig. c) (q. and n.s.w.); _desmoceras flindersi_ (q. and n.s.w.); _schloenbachia inflatus_ (q.); _scaphites cruciformis_ (n. terr.); _ancyloceras flindersi_ (q. and n.s.w.); _crioceras australe_ (fig. d) (q. and s.a.); _belemites australis_ (q.); _b. oxys_ (q., n.s.w., and s.a.); _b. sellheimi_ (q. and s.a.); _b. diptycha_, = _canhami_, tate, (q., n.s.w., and s.a.); and _b. eremos_ (centr. s.a.). =upper cretaceous cephalopods.--= in the upper cretaceous (desert sandstone) of queensland there occurs a belemnite somewhat resembling _belemnites diptycha_, but with a very pointed apex. =cretaceous cephalopods, new zealand.--= in new zealand the amuri system (cretaceous) contains fossils which have been referred to the genera _ammonites_, _baculites_, _hamites_, _ancyloceras_ and _belemnites_, but probably these determinations require some further revision. a species of belemnite has also been noted from probable cretaceous beds in papua. the cainozoic system in victoria contains a true _nautilus, n. geelongensis_; and _aturia australis_ (fig. e), a nautiloid shell having zig-zag suture lines and septal necks enclosing the siphuncle. _a. australis_ is also found in the oamaru series of new zealand; in victoria it has an extensive vertical range, from balcombian to kalimnan (oligocene to lower pliocene). species of _nautilus_ are also found in the janjukian of the murray river cliffs; where, in some cases the shell has been infilled with clear gypsum or selenite, through which can be seen the tubular siphuncle in its original position. _spirulirostra curta_ (fig. f) is an interesting cuttle-bone of rare occurrence. the genus is represented by two other species only, occurring in the miocene of italy and germany. in victoria it is occasionally found in the janjukian marly limestone at bird rock near torquay. common or characteristic fossils of the foregoing chapter. pelecypoda. _ambonychia, macroptera_, tate. cambrian: s. australia. (?) _modiolopsis knowsleyensis_, chapm. l. ordovician: victoria. _orthonota australis_, chapm. silurian (melbournian): victoria. _grammysia cuneiformis_, eth. fil. silurian (melbournian): victoria. _leptodomus maccoyianus_, chapm. silurian (melbournian): victoria. _edmondia perobliqua_, chapm. silurian (melbournian): victoria. _cardiola cornucopiae_, goldfuss sp. silurian (melbournian): victoria. _panenka gippslandica_, mccoy sp. silurian (tanjilian): victoria. _ctenodonta portlocki_, chapm. silurian: victoria. _nuculites maccoyianus_, chapm. silurian: victoria. _nucula melbournensis_, chapm. silurian (melb.): victoria. _palaeoneilo victoriae_, chapm. silurian (melb.): victoria. _pterinea lineata_, goldfuss. silurian (yeringian): victoria. _lunulicardium antistriatum_, chapm. silurian (tanj.): victoria. _conocardium costatum_, cressw. sp. silurian: victoria. _conocardium davidis_, dun. silurian: new south wales. _actinopteria boydi_, conrad sp. silurian (yer.): victoria. _aviculopecten spryi_, chapm. silurian (melb.): victoria. _modiolopsis complanata_, sowerby sp. silurian (melb.): victoria. _goniophora australis_, chapm. silurian (yer.): victoria. _cypricardinia contexta_, barrande. silurian (yer.): victoria. _paracyclas siluricus_, chapm. silurian (melb.): victoria. _actinopteria australis_, dun. devonian: new south wales. _lyriopecten gracilis_, dun. devonian: new south wales. _leptodesma inflatum_, dun. devonian: new south wales. _stutchburia farleyensis_, eth. fil. carbopermian: new south wales. _edmondia nobilissima_, de koninck. carbopermian: new south wales. _deltopecten limaeformis_, morris sp. carbopermian: new south wales, queensland and tasmania. _aviculopecten squamuliferus_, morris sp. carbopermian: new south wales and tasmania. _aviculopecten tenuicollis_, dana sp. carbopermian: new south wales and w. australia. _chaenomya etheridgei_, de koninck sp. carbopermian: new south wales and queensland. _maeonia elongata_, dana. carbopermian: new south wales. _pachydomus globosus_, j. de c. sow. sp. carbopermian: new south wales, tasmania and queensland. _eurydesma cordatum_, morris. carbopermian: new south wales and queensland. _unio dunstani_, eth. fil. trias: new south wales. _unionella carnei_, eth. fil. trias: new south wales. _corbicula burrumensis_, eth. fil. trias: queensland. _daonella lommeli_, wissm. sp. trias: new zealand. _mytilus problematicus_, zittel. trias: new zealand. _monotis salinaria_, zittel. trias: new zealand. _cucullaea semistriata_, moore. jurassic: w. australia. _trigonia moorei_, lycett. jurassic: w. australia. _ctenostreon pectiniforme_, schlotheim sp. jurassic: w. australia. _astarte cliftoni_, moore. jurassic: w. australia. _unio dacombei_, mccoy. jurassic: victoria. _unio eyrensis_, tate. jurassic: s. australia. _nucula truncata_, moore. lower cretaceous: queensland and s. australia. _maccoyella reflecta_, moore sp. l. cretaceous: new south wales, queensland (also u. cretaceous), and s. australia. _maccoyella barkleyi_, moore sp. l. cretaceous: new south wales, queensland and s. australia. _fissilunula clarkei_, moore sp. l. cretaceous: new south wales, queensland, and s. australia; also up. cret. in queensland and south australia. _inoceramus carsoni_, mccoy. lower cretaceous: queensland. _trigonia cinctuta_, eth. fil. lower cretaceous: s. australia. _mytilus rugocostatus_, moore. lower cretaceous: queensland and s. australia. _cyrenopsis opallites_, eth. fil. upper cretaceous: new south wales. _conchothyra parasitica_, hutton. cretaceous: new zealand. _dimya dissimilis_, tate. cainozoic (balc.-kal.): victoria and south australia. _spondylus pseudoradula_, mccoy. cainozoic (balc.-kal.): victoria and south australia. _pecten polymorphoides_, zittel. cainozoic (balc.-kal.): victoria and south australia; also new zealand. _cucullaea corioensis_, mccoy. cainozoic (balc.-kal.): victoria and south australia. _leda vagans_, tate. cainozoic (balc.-kal.): victoria and south australia. _corbula ephamilla_, tate. cainozoic (balc.-kal.): victoria and south australia. _modiola praerupta_, pritchard. cainozoic (balc.): victoria. _pecten praecursor_, chapm. cainozoic (janjukian): victoria. _modiola pueblensis_, pritchard. cainozoic (janjukian): victoria. _limopsis insolita_, sow. sp. cainozoic (janjukian): victoria and s. australia. also oamaru ser., n.z. _cardita tasmanica_, tate. cainozoic (janj.): tasmania. _lucina planatella_, tate. cainozoic (janj.): victoria and tasmania. _pecten novaeguineae_, t. woods. cainozoic (?lower pliocene), yule island, papua. _ostrea manubriata_, tate. cainozoic (kal.): victoria. _glycimeris halli_, pritch. cainozoic (kal.): victoria. _limopsis beaumariensis_, chapm. cainozoic (kalimnan and werrikooian): victoria. _trigonia howitti_, mccoy. cainozoic (kal.): victoria. _meretrix paucirugata_, tate sp. cainozoic (kal.): victoria. _venus (chione) subroborata_, tate, sp. cainozoic (kal.): victoria and south australia. scaphopoda. _dentalium tenuissimum_, de koninck. mid. devonian: new south wales. _dentalium huttoni_, bather. jurassic: new zealand. _dentalium wollumbillensis_, eth. fil. l. cretaceous: queensland. _dentalium, mantelli_, zittel. cainozoic: victoria, s. australia and new zealand. polyplacophora. _chelodes calceoloides_, eth. fil. silurian: new south wales. _ischnochiton granulosus_, ashby and torr sp. cainozoic (balc.): victoria. _lorica duniana_, hull. cainozoic (janjukian): tasmania. _cryptoplax pritchardi_, hall. cainozoic (kal.): victoria. gasteropoda. _ophileta subangulata_, tate. cambrian: s. australia. _platyceras etheridgei_, tate. cambrian: s. australia. _salterella planoconvexa_, tate. cambrian: s. australia. _salterella hardmani_, foord. cambrian: w. australia. _hyolithes communis_, billings. cambrian: s. australia. _scenella tenuistriata_, chapm. cambrian (upper): victoria. _ophileta gilesi_, tate. ordovician: s. australia. _raphistoma browni_, tate. ordovician: s. australia. _hyolithes leptus_, chapm. lower ordovician: victoria. _helicotoma johnstoni_, eth. fil. ordovician: tasmania. _coleolus (?) aciculum_, j. hall. silurian (melb.): victoria. _hyolithes spryi_, chapm. silurian (melb.): victoria. _conularia ornatissima_, chapm. silurian (melb.): victoria. _phanerotrema australis_, eth. fil. silurian (yer.): victoria. _gyrodoma etheridgei_, cressw. sp. silurian (yer.): victoria. _trematonotus pritchardi_, cressw. silurian (yer.): victoria. _bellerophon cresswelli_, eth. fil. sp. silurian (yer.) victoria. _euomphalus northi_, eth. fil. sp. silurian (yer.): victoria. _cyclonema australis_, eth. fil. silurian (yer.): victoria. _trochonema montgomerii_, eth. fil. sp. silurian: tasmania. _bellerophon jukesii_, de koninck. silurian: new south wales. _conularia sowerbii_, defrance. silurian: victoria and new south wales. _euomphalus culleni_, dun. devonian: new south wales. _gosseletina australis_, eth. fil. carboniferous: new south wales. _yvania konincki_, eth. fil. carboniferous: new south wales; and carbopermian: queensland. _bellerophon costatus_, sow. carbopermian: w. australia. _mourlonia humilis_, de koninck. carbopermian: west australia and new south wales. _pleurotomaria (ptychomphalina) morrisiana_, mccoy. carbopermian: new south wales. _keeneia platyschismoides_, eth. fil. carbopermian (lower marine): new south wales. _platyschisma oculum_, sow. sp. carbopermian: new south wales and queensland. _macrocheilus filosus_, sow. carbopermian: new south wales. _loxonema babbindonensis_, eth. fil. carbopermian: new south wales. _conularia tenuistriata_, mccoy. carbopermian: new south wales and queensland. _conularia tasmanica_, carbopermian: tasmania. _murchisonia carinata_, etheridge. carbopermian: queensland. _pleurotomaria greenoughiensis_, eth. fil. jurassic: w. australia. _turbo australis_, moore. jurassic: w. australia. _rissoina australis_, moore. jurassic: w. australia. _cinulia hochstetteri_, moore. cretaceous: queensland and s. australia. _natica ornatissima_, moore. cretaceous: s. australia. _pseudamaura variabilis_, moore sp. cretaceous: new south wales, queensland and s. australia. _anchura wilkinsoni_, eth. fil. cretaceous: queensland and s. australia. _rostellaria waiparensis_, hector. cretaceous: new zealand. _niso psila_, t. woods. cainozoic (balc.-kal.): victoria and s. australia. _crepidula unguiformis_, lam. cainozoic (balc.-recent): victoria and tasmania. _natica hamiltonensis_, tate. cainozoic (balc.-recent): victoria and south australia. _turritella murrayana_, tate. cainozoic (balc.-kal.): victoria, s. australia and tasmania. _cerithium apheles_, t. woods. cainozoic (balc.-kal.): victoria. _volutilithes antiscalaris_, mccoy sp. cainozoic (balc.-werrikooian): victoria. _ancilla pseudaustralis_, tate sp. cainozoic (balc.-kal.): victoria, s. australia and tasmania. _cypraea ampullacea_, tate. cainozoic (balc.): victoria. _murex didyma_, tate. cainozoic (balc.): victoria. _eburnopsis aulacoessa_, tate. cainozoic (balc.): victoria. _cancellaria calvulata_, tate. cainozoic (balc.): victoria. _vaginella eligmostoma_, tate. cainozoic (balc.): victoria. _eutrochus fontinalis_, pritchard. cainozoic (janjukian): victoria. _turbo atkinsoni_, pritchard. cainozoic (janjukian): tasmania and victoria. _scala lampra_, tate sp. cainozoic (janjukian): s. australia. _natica gibbosa_, hutton. cainozoic (janjukian): victoria. also oamaru and wanganui series: new zealand. _morio wilsoni_, tate. cainozoic (janjukian): victoria. _voluta heptagonalis_, tate. cainozoic (janjukian): s. australia. _volutilithes anticingulatus_, mccoy sp. cainozoic (janjukian): victoria and tasmania. also papua. _bathytoma paracantha_, t. woods sp. cainozoic (janj.): victoria and tasmania. also papua. _dolium costatum_, deshayes. cainozoic. (? lower pliocene): yule island, papua. _bankivia howitti_, pritch. cainozoic (kal.): victoria. _eglisia triplicata_, tate sp. cainozoic (kal.): victoria. _voluta masoni_, tate. cainozoic (kal.): victoria. _ancilla papillata_, tate sp. cainozoic (kal.): victoria. _drillia wanganuiensis_, hutton. cainozoic (kal.): victoria. also petane series: new zealand. _terebra geniculata_, tate. cainozoic (kal.): victoria. _pleurotomaria tertiaria_, mccoy. cainozoic (kal.): victoria. also oamaru series: new zealand. _scala lyrata_, zittel sp. cainozoic (oamaru): new zealand. _natica darwinii_, hutton. cainozoic (oamaru): new zealand. _turritella cavershamensis_, harris. cainozoic (oamaru): new zealand. _ancilla hebera_, hutton sp. cainozoic (oamaru): new zealand. also (balc. and janj.): victoria, south australia and tasmania. _pleurotoma hamiltoni_, hutton. cainozoic (oamaru): new zealand. _natica ovata_, hutton. cainozoic (awatere series): new zealand. _struthiolaria sulcata_, hutton. cainozoic (awatere series): new zealand. _trophon expansus_, hutton. cainozoic (petane series): new zealand. _pisania drewi_, hutton. cainozoic (petane series): new zealand. _bankivia fasciata_, menke. cainozoic (werrikooian-recent): victoria. _astralium aureum_, jonas sp. cainozoic (werrikooian-recent): victoria. _natica subinfundibulum_, tate. cainozoic (balc.-werr.): victoria and s. australia. _nassa pauperata_, lam. cainozoic (werr.-rec.): victoria. _helix tasmaniensis_, sow. cainozoic (pleistocene): tasmania. _helix geilstonensis_, johnston. cainozoic (pleistocene): tasmania. _panda atomata_, gray sp. cainozoic (pleist.-rec.): victoria and new south wales. cephalopoda. _endoceras warburtoni_, eth. fil. ordovician: s. australia. _orthoceras gossei_, eth. fil. ordovician: s. australia. _orthoceras ibiciforme_, tate. ordovician: s. australia. _trochoceras reticostatum_, tate. ordovician: s. australia. _actinoceras tatei_, eth. fil. sp. ordovician: s. australia. _orthoceras capillosum_, barrande. silurian: victoria. _orthoceras lineare_, münster sp. silurian (yer.): victoria. _cycloceras bullatum_, sow. sp. silurian (melbournian): victoria. _cycloceras ibex_, sow. sp. silurian (melbournian): victoria. _kionoceras striatopunctatum_, münster sp. silurian (tanjilian): victoria. _phragmoceras subtrigonum_, mccoy. mid. devonian: victoria. _gyroceras philpi_, eth. fil. mid. devonian: queensland. _orthoceras striatum_, sow. carbopermian: new south wales. _agathiceras micromphalum_, morris sp. carbopermian: new south wales and w. australia. _gastrioceras jacksoni_, eth. fil. carbopermian: w. australia. _actinoceras hardmani_, eth. fil. carbopermian: n.w. australia. _nautilus perornatus_, crick. jurassic: w. australia. _dorsetensia clarkei_, crick. jurassic: w. australia. _normanites australis_, crick sp. jurassic: w. australia. _perisphinctes championensis_, crick. jurassic: w. australia. _ammonites aucklandicus_, hector. jurassic: new zealand. _belemnites aucklandicus_, hector. jurassic: new zealand. _nautilus hendersoni_, eth. fil. lower cretaceous: queensland. _haploceras daintreei_, etheridge sp. lower cretaceous: queensland and new south wales. _ancyloceras flindersi_, mccoy. lower cretaceous: queensland and new south wales. _crioceras australe_, moore. lower cretaceous: queensland and s. australia. _scaphites eruciformis_, eth. fil. lower cretaceous: northern territory. _belemnites diptycha_, mccoy. lower cretaceous: queensland, new south wales, and s. australia. _belemnites eremos_, tate. lower cretaceous: s. australia. _nautilus geelongensis_, foord. cainozoic (janjukian): victoria. _aturia australis_, mccoy. cainozoic (balc.-kal.): victoria. oamaru series: new zealand. _spirulirostra curta_, tate. cainozoic (janjukian): victoria. * * * * * literature. mollusca. cambrian.--foord, a. h. geol. mag., dec. iii. vol. vii. , pp. , (pteropoda). tate, r. trans. r. soc. s. austr., vol. xv. , pp. - (pelec. and gastr.), pp. , (pteropoda). etheridge, r. jnr. trans. r. soc. s. austr., vol. xxix. , p. (pteropoda). chapman, f. proc. r. soc. vict., vol. xxiii. pt. ii. , pp. , (gastr.). ordovician.--etheridge, r. jnr. parl. papers, leg. assemb., s. austr., no. , , pp. , (gastr. and ceph.). tate, r. rep. horn. sci. exped., pt. , , pp. - . chapman, f. proc. r. soc. vic., vol. xv. pt. ii. , pp. , (_hyolithes_). silurian.--mccoy, f. prod. pal. vic., dec. vi. , pp. - . etheridge, r. jnr. rec. austr. mus., vol. i. no. , , pp. - (gastr.). idem, ibid., vol. i. no. , , pp. - (pelec. and gastr.). cresswell, a. w. proc. r. soc. vict., vol. v. , pp. - . etheridge, r. jun. rec. austr. mus., vol. iii. no. , , pp. - (gastr.). idem, rec. geol. surv. new south wales, vol. v. pt. , , pp. - (_chelodes_). de koninck, l. g. mem. geo. surv. new south wales, pal. no. , , pp. - . etheridge, r. jnr. prog. rep. geol. surv. vict., no. xi. , pp. , (pelec.). idem, rec. austr. mus., vol. v. no. , , pp. - (ceph.). chapman, f. proc. r. soc., vict., vol. xvi. pt. . , pp. - (pteropoda). idem, mem. nat. mus. melbourne, no. , (pelecypoda). devonian.--mccoy, f. prod. pal., vict., dec. iv. , pp. , (ceph.). etheridge, r. jnr. geol. and pal. queensland, , p. (_gyroceras_). de koninck, l. g. mem. geol. surv. new south wales, pal. no. , , pp. - . carboniferous.--etheridge, r. jnr. rec. austr. mus., vol. iii. no. , , pp. - (_actinoceras_). idem, geol. surv. w.a., bull. no. , , pp. - . carbopermian.--morris, j., in strzelecki's phys. descr. of new south wales, etc., , pp. - and - . foord, a. h. geol. mag., dec. iii. vol. vii. , pp. , . etheridge, r. jnr. geol. and pal. queensland, , pp. - . idem., proc. linn. soc. new south wales, vol. ix. , pp. - (pelec. and gastr.). de koninck, l. g. mem. geol. surv. new south wales, pal. no. , , pp. - . etheridge, r. jnr. and dun, w. s. mem. geol. surv. new south wales, pal. no. , vol. ii. pt. i. (_palaeopecten_). idem, ibid., vol. ii., pt. , (_eurydesma_). trias.--zittel, k. novara exped., vol. i. abth. ii. geol. theil., , pp. - . etheridge, r. jnr. mem. geol. surv. new south wales, pal. no. , , pp. - . jurassic.--zittel, k. novara exped., vol. i., abth. ii. geol. theil., , pp. - . moore, c. quart. journ. geol. soc., vol. xxvi. pp. - (jurassic and cretaceous moll.). etheridge, r. jnr. ibid., vol. xxviii. , pp. - (palaeozoic, jur. and cret. moll.). crick, g. c. geol. mag., dec. iv. vol. i. , pp. and - (ceph.). chapman, f. proc. r. soc. vict., vol. xvi. pt. ii. , pp. - . marshall, p. trans. new zealand inst., vol. xli. , pp. - (new zealand ceph.). etheridge, r. jnr. geol. surv. w.a. bull. no. , , pp. - . cretaceous.--etheridge, r. jnr. geol. and pal. queensland, , pp. - and - . idem, geol. surv. queensland, bull. no. , , pp. - . idem, mem. roy. soc. s. aust., vol. ii. pt. , (s.a. moll.). idem, mem. geol. surv. new south wales, pal. no. , , pp. - (new south wales moll.). cainozoic.--zittel, k. novara exped. geol. theil., vol. i. abth. ii. , pp. - (pelec. and gastr. new zealand). mccoy, f. prod., pal. vict., dec. i. ; dec. ii. ; dec. iii. ; dec. v. ; dec. vi. . woods, j. e. t. proc. r. soc. tas. ( ), , pp. - (table cape moll.). idem, proc. linn. soc. new south wales, vol. iii. , pp. - (muddy creek moll.). idem, ibid., vol. iv. , pp. - . hutton, f. w. trans. new zealand inst. vol. ix. , pp. - . ibid., vol. xvii. , pp. - (new zealand pelec. and gastr.). idem, proc. linn. soc. new south wales, vol. i. nd ser. ( ), , pp. - , (distr. lists, pareora and oamaru). idem, macleay, mem. vol. linn. soc. new south wales, , pp. - (pliocene moll. new zealand). tate, r. trans. r. soc. s. austr., vol. vii. , pp. - , and vol. ix., , pp. - (pelec.); ibid., pp. - (scaphopoda); ibid., - (pteropoda). idem, ibid., vol. x. , pp. - ; vol. xi. , pp. - ; vol. xiii. , pp. - ; and vol. xvii. , pp. - (gastr.). idem, journ. r. soc., new south wales, vol. xxvii. , pp. - . idem, ibid., vol. xxxi. , pp. - (gastr. and pelec.). idem, trans. roy. soc. s. austr., vol. xxiii. , pp. - (revision of moll.). pritchard, g. b. proc. roy. soc. vic., vol. vii. , pp. - (pelec.). idem, ibid., vol. viii. , pp. - (moll. of t. cape). idem, ibid., vol. xi. pt. i. , pp. - (gastr.). idem, ibid., vol. xiv. pt. i. , pp. - (pelec.). idem, ibid., vol. xvi. pt. ii. , pp. - (pelec.). idem, ibid., vol. xvi. pt. i. , pp. - (_pleurotomaria_). idem, ibid., vol. xvii. pt. i. , pp. - (gastr.) idem, ibid., vol. xxvi. (n.s.) pt. i. , pp. - (volutes). hall, t. s. proc. r. soc. vict., vol. xvii. pt. ii. , pp. - (chitons). ashby, e. and torr. w. g. trans. r. soc. s. austr., vol. xxv. , pp. - (chitons). thomson, j. a. trans. new zealand inst., vol. xl. , pp. , (n.z. moll.). chapman, f. proc. r. soc. vict. vol. xx. pt. ii. , pp. - (chiton). idem, ibid., vol. xxv. pt. i. , pp. - (gastr.). chapter xi. fossil trilobites, crustacea and insects. =arthropods and their structure.--= the above-named fossil groups are included by zoologists in the sub-kingdom arthropoda ("joint-footed animals"). the arthropods possess a body and limbs composed of a number of jointed segments covered externally with a hard, shelly material and separated by a softer, flexible skin. they have no internal skeleton, and therefore the only portion which can be preserved in the fossil state is the harder part of the outer covering. under exceptional conditions of fossilisation, however, even frail insects such as ants, wasps and dragon-flies are sometimes found more or less wholly preserved and showing their original minute structure. =subdivisions of arthropoda.--= the principal representatives of the group of the arthropods which are found as fossils include the trilobites; various crustacea proper, as crabs, lobsters, shrimps, pod-shrimps and water-fleas; the insects; and occasionally spiders and scorpions (arachnida). the king-crabs and eurypterids (as the extinct _pterygotus_) form a separate sub-class, the merostomata, which are placed by some authors in the group of spiders and scorpions: their remains date back to the time when the older palaeozoic strata were deposited. =crustacea, an archaic group.--= a typical division of the arthropod group, and one which was well represented from the earliest period up to the present day, is the _crustacea_. as the name denotes, these animals are generally invested with a strong shelly covering or "crust," usually of horny or chitinous material, which in some forms is strengthened by deposits of phosphate of lime. of the horny condition of the shell the groups of the bivalved crustacea (ostracoda) and the "water-fleas" (entomostraca) supply notable instances; whilst the limy-structured shell is seen in the common crab. some authorities separate the great extinct group of the trilobites from the rest of the crustacea; but it will here be convenient, in a preliminary study, to consider them together. =development of crustacea.--= the development of the lower forms of the crustacea is interesting, from the fact that the young usually escapes from the egg in a larval state known as a "nauplius." in this stage there are no segments to the body, and but a solitary median eye, such as may be seen in the common water-flea known to microscopists as _cyclops_. the three pairs of appendages seen in this larval crustacean represent the two pairs of antennae and the jaws or mandibles of the full-grown form. among the higher crustacea, however, there is no larval form; the young escaping from the egg in a more or less highly developed condition resembling the adult. the group of the crabs, lobsters and shrimps (or decapoda, _i.e._, having ten ambulatory feet) exhibit a larval stage in which the young form ("zoea") has a segmented abdomen and seven pairs of appendages. =trilobites.--= the first group of arthropods here described is that of the _trilobites_. these were so named on account of the three-lobed form of the body. this particular feature distinguishes them from the crustacea proper; which includes the phyllopods (with leaf-like limbs), as the freshwater _estheria_, the ostracoda or bivalved water-fleas, the barnacles or cirripedia and the higher crustacea (malacostraca), including shrimps, crabs, and lobsters, of which the oldest representatives are the pod-shrimps (phyllocarida). =habits of trilobites.--= the remains of these primitive but often strikingly ornamented crustacean-like animals, the trilobites, are found in comparative abundance in the limestones, mudstones, and even the sandstones of the older sedimentary rocks of australasia. they were amongst the most prolific types of animal life existing in the seas of palaeozoic times, and are especially characteristic of cambrian, ordovician and silurian rocks. trilobites, as a group, seem to have adapted themselves to almost all conditions of marine life: some are found in the hardened black mud of shallow waters, whilst others are to be looked for in the limestones and excessively fine sediments of deeper waters. in all probability certain of these forms crawled over the soft, oozy sea-bed in order to obtain their food, and consequently their remains in the stratified rocks would be restricted to the fine black shales; whilst the freely swimming forms could change their habitat at will, and would be found alike in sandy or clayey deposits. as some indication of their varied habits, the eyes of trilobites differ greatly in size. they are always compound like the eye of the house-fly, though of a semi-lunar shape. in some forms the eyes are very small or even absent, whilst in others they are exceedingly large and prominent. this latter feature probably indicates their frequenting moderately deep water. [illustration: =fig. --diagram-restoration of an australian trilobite.= (dalmanites meridianus, eth. fil. and mitch, sp.) to show the sutures or joints, and the structure of the back of the carapace. about / natural size. ] =structure of trilobites.--= the complete structure and zoological relationship of the trilobites has always been open to some doubt. as regards the former, within recent years exceptionally well-preserved specimens from the utica slates and the cincinnati limestone of ohio, rocks of ordovician age, have been discovered and dissected, whereby our knowledge of the organisation of this group is greatly advanced. these remarkable fossil remains show that the trilobites bore on their under surface a number of appendages, one pair to each segment, except that of the anal. the front pair is whip-like and served as antennae; the others are branched, the forward portion being a crawling limb, and the hinder, which was fringed with bristles or thin plates, may have served either for swimming or breathing. at the base of the four pairs of appendages attached to the head there was an arrangement for biting the food, from whence it was passed to the mouth. taking one of the commonest australasian trilobites, _dalmanites meridianus_, for an example of general structure, and looking at the back of the shell or upper surface, we see the trilobate (three-lobed) form well defined (fig. ). the central ridge is termed the axis, and on either side of this are arranged the pleural lobes, each well marked transverse division of which, in the central or thoracic region, being a pleuron or rib. the whole body is divided into three more or less distinct portions,--the head-shield or cephalon, the thorax, and the tail-shield or pygidium. the central area of the head-shield is called the glabella or cranidium, against which, on either side, are placed the free cheeks carrying the compound sessile eyes when present. the appendages of the head are pediform or leglike, arranged in five pairs, and biramous or forked, excepting the antennae, which are simple and used as sensory organs. in front of the mouth is the hypostoma or forelip, and behind it is the metastoma or hind-lip. the segments of the head-shield are most closely united, and in all the trilobites are of the same number. those of the thorax have flexible joints and are variable in number. the segments of the abdomen are fused together and form a caudal shield or pygidium. the larval stage of the trilobite was a protonauplian form (that is more primitive than the nauplius), the protoaspis; the adult stage, being attained by the addition of segments at the successive moults. the earliest known trilobites in australia are some cambrian species from south australia, western australia, victoria, and tasmania. =lower cambrian trilobites.--= [illustration: =fig. --cambrian trilobites.= a--ptychoparia howchini, eth. fil. l. cambrian. south australia b--dolichometopus tatei, h. woodw. l. cambrian. south australia c--agnostus australiensis, chapm. up. cambrian. victoria d--ptychoparia thielei, chapm. up. cambrian. victoria e--dikellocephalus florentinensis, eth. fil. l. cambrian. tasmania ] in the lower cambrian limestone of yorke peninsula, south australia, the following trilobites occur:--a species doubtfully referred to _olenellus_ (? _o. pritchardi_); _ptychoparia howchini_ (fig. a); _p. australis_; _dolichometopus tatei_ (fig. b); and _microdiscus subsagittatus_. the cambrian of the northern territory contains _olenellus brownii_. in western australia _olenellus forresti_ is found in similar beds. =upper cambrian trilobites.--= the dolodrook limestone (upper cambrian) of gippsland, victoria, contains the remains of the primitive little trilobite _agnostus_ (_a. australiensis_, fig. c); _crepicephalus_ (_c. etheridgei_); and _ptychoparia_ (_p. thielei_ (fig. d) and _p. minima_). the upper cambrian sandstones of caroline creek, tasmania, contain _dikellocephalus_ (_d. tasmanicus_); a species of _asaphus_ and _ptychoparia_ (_p. stephensi_). beds of the same age in the florentine valley, tasmania, have yielded _dikellocephalus_ (_d. florentinensis_, fig. e). =ordovician trilobites.--= trilobites of lower ordovician age or even older, are found in the knowsley beds near heathcote in victoria. they are referred to two genera, _dinesus_ and _notasaphus_. both forms belong to the ancient family of the asaphidae. associated with these trilobites are some doubtful species of sea-weed, spicules of siliceous sponges, traces of threadlike hydrozoa, some fragments of graptolites allied to _bryograptus_, and several brachiopods. at the lyndhurst gold-fields, near mandurama, new south wales, trilobites related to the genus _shumardia_ have been found associated with brachiopods (lamp-shells), pteropods (sea-butterflies), and graptolites (hydrozoa) of an upper ordovician facies. the limestone beds at laurie's creek and other localities in central australia contain remains of _asaphus illarensis_, _a. howchini_ and _a. lissopelta_; whilst in the limestone and quartzite of middle valley, tempe downs, _a. thorntoni_ also occurs. =silurian trilobites.--= [illustration: =fig. --older silurian trilobites.= a--ampyx parvulus, forbes, var. jikaensis, chapm. silurian (melb.) victoria b--cypaspis spryi, gregory. silurian (melb.) victoria c--homalonotus harrisoni, mccoy. silurian (melb.) victoria d--phacops latigenalis, eth. fil. and mitch. silurian. n.s. wales ] trilobites are well-known fossils in the australasian silurian strata. as they occur rather abundantly along with other fossils in rocks of this age they are extremely useful aids in separating the system into the different beds or zones. in victoria the silurian is divisible into two sets of beds: an older, or melbournian stage (the bed-rock of melbourne) and a younger, yeringian (lilydale series). trilobites of melbournian age are found to belong to the genera _ampyx_, _illaenus_, _proetus_, _cyphaspis_, _encrinurus (cromus)_ and _homalonotus_. the commonest species are _cyphaspis spryi_ (fig. b), and _encrinurus (cromus) spryi_ from the south yarra mudstones; and _ampyx parvulus_, var. _jikaensis_ (fig. a), and _homalonotus harrisoni_ (fig. c), from the sandstone of moonee ponds creek. the handsome _dalmanites meridianus_ and _homalonotus vomer_ occur at wandong in what appear to be passage beds between the melbournian and yeringian. the yeringian of victoria is far richer in trilobites than the preceding series, and includes the genera _proetus_, _cyphaspis_, _bronteus_, _lichas_, _odontopleura_, _encrinurus_, _calymene_, _homalonotus_, _cheirurus_, and _phacops_. the rocks in this division occur as mudstones, limestones, and occasionally sandstones and conglomerates. the mudstones, however, prevail, and these pass insensibly into impure limestones of a blue-black colour, weathering to brown, as at seville; the change of structure indicating less turbid water. at lilydale, and on the thomson river, as well as at loyola and waratah bay, almost pure limestone occurs, which represents clear water conditions, not necessarily deep; there, however, trilobites are scarce, and the prevailing fauna is that of an ancient coral reef. some described yeringian species are _lichas australis_ (fig. a), _odontopleura jenkinsi_ (fig. b) (found also in new south wales), _encrinurus punctatus_ (fig. c), _calymene tuberculosa_, _bronteus enormis_, _phacops sweeti_, and _p. serratus_ (fig. e). in _calymene_ ("covered up") the joints of the thorax are facetted at the angles, so that each pleuron could work over that immediately behind; in consequence of this it could roll itself up like a woodlouse or slater, hence the name of the genus. this trilobite also occurs in england, and is there known amongst the quarry men and fossil collectors as the "dudley locust." perhaps the most characteristic and common trilobite of the yeringian series in victoria is _phacops sweeti_ (fig. d), formerly identified with barrande's _p. fecundus_, from which it differs in the longer and larger eye with more numerous lenses. it is found in victoria in the upper yarra district near the junction of the woori yallock and the yarra rivers; north-west of lilydale; near seville; at loyola near mansfield; and at fraser's creek near springfield, kilmore. [illustration: =fig. --newer silurian trilobites.= a--lichas australis, mccoy. silurian (yeringian). victoria b--odontopleura jenkinsi. eth. fil. and mitch. silurian. n.s. wales c--encrinurus punctatus, brunnich sp. silurian. n.s. wales. d--phacops sweeti, eth. fil. and mitch. silurian. n.s. wales e--phacops serratus, foerste. silurian. n.s. wales ] in new south wales trilobites are abundant in the yass district, amongst other localities, where the upper beds, corresponding to the yeringian of victoria, are well developed. _dalmanites meridianus_ is common to the silurian of new south wales, victoria, and tasmania. in victoria this handsome species is found in the hard, brown, sandy mudstone of broadhurst's and kilmore creeks, and, as previously noted, in the hard, blue mudstone of wandong. at the latter locality specimens may be found in the railway ballast quarry, where they are known to the workmen as "fossil butterflies." the species also occurs at the famous fossil locality of hatton's corner, yass; at bowning; and at limestone creek, all in new south wales. other trilobites occurring in the silurian of new south wales are _odontopleura jenkinsi_, _o. bowningensis_, _cheirurus insignis_ and _phacops latigenalis_ (fig. d). in the wangapeka series of new zealand the calcareous shales and limestones of the upper division contain _calymene blumenbachii_, _homalonotus knightii_ and _h. expansus_. =devonian trilobites.--= trilobites suddenly became rare in the australian devonian. the only known examples of trilobite remains belong to a species of _cheirurus_ occasionally found in the middle devonian limestone of buchan, victoria; and a species of _proetus_ in the devonian of barker gorge, napier range, west australia. =carbopermian trilobites.--= trilobites of carbopermian age are found in new south wales, queensland, and western australia. all the genera belong to the family proetidae. the genera _phillipsia_ (_p. seminifera_, fig. a), _griffithides_ (_g. eichwaldi_, fig. b), and _brachymetopus_ (_b. strzelecki_, fig. c) occur in new south wales. _griffithides eichwaldi_ is also found in queensland. other queensland species are _phillipsia woodwardi_, _p. seminifera_ var. _australasica_ and _p. dubia_. _phillipsia grandis_ is found in the carbopermian of the gascoyne river, western australia. [illustration: =fig. --carboniferous trilobites and a phyllopod.= a--phillipsia seminifera, phillips. carboniferous. n.s. wales b--griffithides eichwaldi, waldheim. carboniferous. n.s. wales c--brachymetopus strzelecki, mccoy. carboniferous. n.s. wales d--estheria coghlani, cox. triassic. n.s. wales ] =phyllopoda in carboniferous, triassic and jurassic.= the _phyllopoda_, which belong to the crustacea in the strict sense of the term, comprise the estheriidae and cladocera (water-fleas). the former group is represented by _leaia mitchelli_, which is found in the upper carboniferous or carbopermian of the newcastle district, new south wales. in the still later hawkesbury series (triassic) of new south wales, _estheria coghlani_ (fig. d) occurs. this species is a minute form, the carapace measuring from . mm. to mm. in the longer diameter of the shell. in the upper part of the wairoa series (triassic) of nelson, new zealand, there is found another species of _estheria_, identified with a european form _e. minuta_. _estheria mangaliensis_ is another form occurring in the jurassic (ipswich series) of queensland. at the present day these little _estheriae_ sometimes swarm in countless numbers in freshwater lakes or salt marshes. =ostracoda: their structure.--= passing on to the next group, the bivalved _ostracoda_, we note that these have existed from the earliest geological periods to the present day. they are usually of minute size, commonly about the sixteenth of an inch in length, although some attained a length of nearly one inch (_leperditia_). their bodies are indistinctly segmented, and are enclosed within a horny or calcareous shell. this shell consists of two valves which are joined along the back by a ligament or hinge, the ends and ventral edge remaining quite free. the pairs of appendages present are the antennae ( ), mandibles ( ), maxillae ( ), and thoracic feet ( ). the only portion found in the fossil state is the bivalved carapace, the two valves being frequently met with still united, especially when these tiny animals have settled down quietly on the sea-bed and have been quickly covered with sediment. =features of the ostracod carapace.--= since the body parts of the ostracod are wanting in the fossil examples, the generic determination is attended with some difficulty, especially in regard to the smooth or bean-shaped forms. the chief distinctive characters to note are, the contour of the carapace seen in three directions (top, side and end views), the structure of the hinge, and the position and figure of the muscle-spots or points of adhesion of the muscular bands which hold or relax the two valves. the valves in certain genera fit closely upon one another. in others, one overlaps the other, the larger being sometimes the right (as in _leperditia_), sometimes the left (as in _leperditella_). the hinge-line is often simple or flange-like, or it may consist of a groove and corresponding bar, or there may be a series of teeth and sockets. lateral eye-tubercles are sometimes seen on the surface of the valve, whilst in the animal there was also a small eye. =habits of ostracoda.--= ostracoda swarmed in many of the streams, lakes and seas of past geological times, and they still exist in vast numbers under similar conditions. like some other minute forms of life, they played a most important part in building up the rock formations of the sedimentary series of the earth's crust; and by the decomposition of the organism itself they are of real economic value, seeing that in some cases their decay resulted in the subsequent production of oil or kerosene shales and bituminous limestones. the carboniferous oil shales in the lothians of scotland, for example, are crowded with the carapaces of ostracoda associated with the remains of fishes. =cambrian ostracoda.--= some undescribed forms of the genus _leperditia_ occur in the hard, sub-crystalline cambrian limestone of curramulka, south australia. =silurian ostracoda.--= in victoria and new south wales the oldest rocks from which we have obtained the remains of ostracoda up to the present, are the uppermost silurians, in which series they occur both in the limestone and the mudstone. in victoria their bivalved carapaces are more often found in the limestone; but one genus, _beyrichia_, is also met with in abundance in the mudstone. these mudstones, by the way, must have originally contained a large percentage of carbonate of lime, since the casts of the shells of mollusca are often excessively abundant in the rock, and the mudstone is cavernous, resembling an impure, decalcified limestone. these yeringian mudstones of victoria seem, therefore, to be the equivalent of the calcareous shales met with in the wenlock and gotland series in europe; a view entirely in accordance with the character of the remainder of the fauna. one of the commonest of the silurian ostracods is _beyrichia kloedeni_, a form having an extensive distribution in europe. it occurs in the silurian mudstone of the upper yarra district. other species of the same genus are _b. wooriyallockensis_ (fig. a), distinguished from the former by differences in the shape of the lobes and its longer valves; also a form with narrow lobes, _b. kilmoriensis_; and the ornate _b. maccoyiana_, var. _australis_. of the smooth-valved forms, mention may be made of _bythocypris hollii_, _b. caudalis_ (fig. d), and the striking form, _macrocypris flexuosa_. regarding the group of the _primitiae_, of which as many as thirteen species and varieties have been described from the lilydale limestone, we may mention as common forms _p. reticristata_ (fig. e) and _p. punctata_. this genus is distinguished by the bean-shaped or purse-shaped carapace, with its well developed marginal flange and mid-dorsal pit. other genera which occur in our silurians and are of great interest on account of their distribution elsewhere. are _isochilina_, _aparchites_, _xestoleberis_, _aechmina_, and _argilloecia_. [illustration: =fig. --silurian ostracoda.= a--beyrichia wooriyallockensis, chapm. silurian (yer.) victoria b--xestoleberis lilydalensis, chapm. silurian (yer.) victoria c--argilloecia acuta, jones and kirkby. silurian (yer.) victoria d--bythocypris caudalis, jones. silurian (yer.) victoria e--primitia reticristata, jones. silurian (yer.) victoria ] the largest ostracod yet described from australia, measuring more than a quarter of an inch in length, occurs in the upper silurian of cliftonwood, near yass, new south wales. it belongs to the genus _leperditia_ (_l. shearsbii_), and is closely related to _l. marginata_, keyserling sp.; which occurs in strata of similar age in the swedish and russian baltic area. a limestone at fifield, new south wales, probably of silurian age, contains _primitia_, _kloedenia_, and _beyrichia_. =devonian ostracoda.--= the little _primitia cuneus_ (fig. a) with a bean-shaped carapace and median pit or depression occurs somewhat frequently in the middle devonian limestone of buchan, victoria. another species, _primitia yassensis_, is found in the shaly rock of narrengullen greek, new south wales. it is probable that many other species of the group of the ostracoda remain to be described from australian devonian rocks. =carboniferous ostracoda.--= in queensland a conspicuous little ostracod is _beyrichia varicosa_ from the star beds of corner creek. =carbopermian ostracoda.--= in the carbopermian of cessnock, new south wales, _primitia dunii_ occurs; and in that of farley is found _jonesina etheridgei_. from both these localities _leperditia prominens_ was also obtained. another species from new south wales is _entomis jonesi_ (fig. b), described from the muree sandstone by de koninck. [illustration: =fig. --upper palaeozoic and mesozoic ostracoda.= a--primitia cuneus, chapm. mid. devonian. victoria b--entomis jonesi, de kon. carboniferous. new south wales c--synaphe mesozoica, chapm. sp. triassic. new south wales d--cythere lobulata, chapm. jurassic. west australia e--paradoxorhyncha foveolata, chapm. jurassic. west australia f--loxoconcha jurassica, chapm. jurassic. west australia g--cytheropteron australiense, chapm. jurassic. west australia ] =triassic ostracoda.--= the triassic (wiannamatta shales) of grose vale, new south wales has afforded a few specimens of ostracoda belonging to _synaphe_ (_s. mesozoica_, fig. c), _? darwinula_, and _? cytheridea_. =jurassic ostracoda.--= the marine jurassic strata of western australia at geraldton, have yielded a small but interesting series of ostracoda, largely of modern generic types. the genera, which were found in a rubbly _trigonia_-limestone, are _cythere_, _paradoxorhyncha_, _loxoconcha_, and _cytheropteron_. [illustration: =fig. --cainozoic ostracoda.= a--bairdia amygdaloides, g. s. brady. balcombian. victoria b--cythere clavigera, g. s. brady. balcombian. victoria c--cythere scabrocuneata, g. s. brady. balcombian. victoria d--cytherella punctata, g. s. brady. balcombian. victoria ] =cainozoic ostracoda.--= the fossiliferous clays and calcareous sands of the southern australian cainozoic beds often contain abundant remains of ostracoda. the moderately shallow seas in which the fossiliferous clays, such as those of balcombe's bay, were laid down, teemed with these minute bivalved crustacea. all the forms found in these beds are microscopic. they either belong to living species, or to species closely allied to existing forms. some of the more prominent of the balcombian species are _cythere senticosa_, a form which is now found living at tenedos, and _c. clavigera_ (fig. b), with the young form sometimes referred to as _c. militaris_, a species which may still be dredged alive in hobson's bay. other genera common in these clays are _bairdia_, with its broad, pear-shaped carapace, represented by the still living _b. amygdaloides_ (fig. a). _cytherella_, with its compressed, subquadrate carapace, as seen in _c. punctata_ (fig. d), a species having an elaborate series of muscle-spots, and which, like the previous species, is found living in australian seas; and _macrocypris_, with its slender, pointed, pear-shaped outline. =cirripedia: their habits and structure.--= _cirripedia or barnacles._--these curious modifications of the higher group of crustacea (eucrustacea) date back to ordovician times. they appear to have tried every possible condition of existence; and although they are mostly of shallow water habits, some are found at the great depth of , fathoms (over two miles). those which secrete lime or have calcareous shells, attach themselves to stones, pieces of wood, shell-fish, crabs, corals and sea-weeds. others are found embedded in the thick skin of whales and dolphins, or in cavities which they have bored in corals or shells of molluscs. some are found parasitic in the stomachs of crabs and lobsters, or within other cirripedes. they begin life, after escaping from the egg, as a free-swimming, unsegmented larva ("nauplius" stage), and before settling down, pass through the free-swimming, segmented "cypris" stage, which represents the pupa condition, and in which state they explore their surroundings in search of a suitable resting place for their final change and fixed condition. just before this occurs, glands are developed in the pupa barnacle, which open into the suckers of the first pair of appendages or antennae. when a suitable place for fixation has been found, these glands pour out a secretion which is not dissolved by water, and thus the barnacle is fixed head downwards to its permanent position. the compound eyes of the "cypris" stage disappear, and henceforth the barnacle is blind. the characteristic plates covering the barnacle are now developed, and the six pairs of swimming feet become the cirri or plumes, with which the barnacle, by incessant waving, procures its food. in short, as remarked by one authority, it is a crustacean "fixed by its head, and kicking the food into its mouth with its legs." cirripedes may be roughly divided into two groups, the acorn barnacles and the goose barnacles. although dissimilar in general appearance, they pass through identical stages, and are closely related in most of their essential characters. the latter forms are affixed by a chitinous stalk or peduncle, whilst the acorn barnacles are more or less conical and affixed by the base. =silurian cirripedes.--= the stalked barnacles are probably the oldest group, being found as far back as the ordovician period. in australia the genus _turrilepas_ occurs in silurian rocks, _t. mitchelli_ (fig. a) being found at bowning in the yass district of new south wales. the isolated plume-like plates of _t. yeringiae_ (fig. b) are not uncommon in the olive mudstone of the lilydale district in victoria. [illustration: =fig. --fossil cirripedia.= a--turrilepas mitchelli, eth. fil. silurian. new south wales b--turrilepas yeringiae, chapm. silurian. victoria c--(?) pollicipes aucklandicus, hector sp. cainozoic (oamaru series). new zealand ] [illustration: =fig. --living and fossil cirripedes.= a--lepas anatifera, l. common goose barnacle. living b--lepas pritchardi, hall. cainozoic. victoria ] =cainozoic lepadidae.--= the genus _lepas_ (the modern goose barnacles) is represented by isolated plates in the cainozoic (janjukian) limestones and marls of waurn ponds, and torquay near geelong: it also occurs in a stratum of about the same age, the nodule bed, at muddy creek, near hamilton, victoria (_l. pritchardi_, fig. ). in new zealand the gigantic cirripede, _?pollicipes aucklandicus_ (fig. c), occurs in the motutapu beds. =cainozoic balanidae.--= the acorn barnacles are represented in our cainozoic shell marls and clays by a species of _balanus_ from the janjukian of torquay; whilst two species of the genus occur in the kalimnan beds at beaumaris, port phillip, in similar beds in the hamilton district, and at the gippsland lakes. =phyllocarida: their structure.--= a large and important group of the higher crustacea, but confined to the older rocks of victoria, is the order _phyllocarida_. this seems to form a link between the entomostraca, including the bivalved ostracoda and the well-known group of the lobsters, shrimps and crabs. the body of these phyllocarids consists of five segments to the head, eight to the thorax, and from two to eight to the abdomen. the portion usually preserved in this group is the carapace, which covers the head and thorax, and although often in one piece, is sometimes hinged, or otherwise articulated along the back. in front of the carapace there is a moveable plate, the rostrum or beak (fig. ). there are two pairs of antennae to the head, and the animal is provided with a pair of stalked compound eyes. the thoracic segments are furnished with soft leaf-like legs as in the phyllopods. the abdomen is formed of ring-like segments, and generally terminates in a sharp tail-piece or telson, often furnished with lateral spines. in many respects the ancient phyllocarids correspond with the living genus _nebalia_, which is found inhabiting the shallow waters of the mediterranean and elsewhere. [illustration: =fig. --ceratiocaris papilio, salter.= silurian. lanarkshire. (_after h. woodward_) ] [illustration: =fig. --ordovician phyllocarids.= a--rhinopterocaris maccoyi, eth. fil. sp. l. ordovician. victoria b--caryocaris angusta, chapm. l. ordovician. victoria c--saccocaris tetragona, chapm. l. ordovician. victoria ] [illustration: =fig. --silurian phyllocarids.= a--ceratiocaris pritchardi, chapm. silurian. victoria b--ceratiocaris cf. murchisoni, agassiz sp. silurian. victoria c--ceratiocaris pinguis, chapm. silurian. victoria ] =ordovician phyllocarids.--= phyllocarids of the lower ordovician slates are referred to the genera _rhinopterocaris_, _caryocaris_, _saccocaris_ and _hymenocaris_. the first-named is the commonest type; and is found in slates of the lancefield, bendigo and castlemaine series at the localities named, as well as at dromana. _rhinopterocaris_ (fig. a) is readily distinguished by its long--ovate outline, and this, together with its wrinkled chitinous appearance makes it resemble the wing of a dipterous insect. _caryocaris_ (fig. b) is a smaller and narrower form which occurs in the victorian lower ordovician slates, as well as in ice-borne blocks derived from the ordovician, at wynyard, in n.w. tasmania. =silurian phyllocarids.--= the chief type of phyllocarid in the silurian is _ceratiocaris_ (fig. ). the carapace is typically ovate, straight on one edge, the dorsal, and convexly curved on the other, the ventral. they resemble bean-pods in outline, hence the name "pod-shrimps." several species are known from the victorian shales, mudstones, and sandstones; the forms found in australia if complete would seldom attain five inches in length, whilst some british species are known to reach the exceptional length of two feet. the long, grooved and jointed telson is not uncommon in the sandstones of melbourne and kilmore. other genera described from victoria are _aptychopsis_ and _dithyrocaris_. =lower cretaceous crab.--= the earliest example of the _decapoda_ in the australian rocks, so far recorded, is the lower cretaceous _prosopon etheridgei_ (fig. a) from queensland, which has affinities with some jurassic and neocomian crabs found in europe. other crustacean remains of less decipherable nature occur in this same deposit. [illustration: =fig. --fossil crabs and insects.= a--prosopon etheridgei, h. woodw. l. cretaceous. queensland b--ommatocarcinus corioensis, cressw. sp. cainozoic (jan.) vic. c--harpactocarcinus tumidus, h. woodw. cainozoic (oamaru). new zealand d--aeschna flindersensis, h. woodw. l. cretaceous. queensland e--ephemera culleni, eth. fil. and olliff. cainozoic (deep leads). new south wales ] =cainozoic crabs.--= of the cainozoic decapod crustacea there is a victorian species of a stalk-eyed crab, _ommatocarcinus corioensis_ (fig. b), found in the marls of curlewis and port campbell, and probably of janjukian age. various portions of similar crustacea, consisting of claws and fragmentary carapaces, are found from time to time in the victorian clays and limestones of balcombian and janjukian ages, but they are insufficient for identification. a carapace of one of the oxystomata (with rounded cephalo-thorax and non-salient frontal region) has occurred in the kalimnan marl of the beaumaris cliffs, port phillip. it is closely allied to a crab now found in hobson's bay and generally along the victorian coast. remains of a shore-crab (fam. cancridae) are found at three localities, in the oamaru series, in new zealand; near brighton, in nelson and at wharekuri in the waitaki valley. it has been described under the name of _harpactocarcinus tumidus_ (fig. c), a genus of the cyclometopa or "bow crabs." =pleistocene lobster.--= numerous remains of a lobster, _thalassina emerii_ (see _antea_, fig. ), supposed to be of pleistocene age, occur in nodules found on queensland and north australian (port darwin) beaches. =eurypterids in the silurian.--= the order _eurypterida_ comprises an extinct group of crustacea closely allied to the modern king-crab (_limulus_). the body was covered with a thin chitinous skeleton, ornamented with regular scale-like markings. this group is represented in victorian rocks by the remains of _pterygotus_ ("sea-scorpions"), animals which often attained a length of six feet. _pterygotus_ (see fig. a) had the fore part of the body fused, forming the cephalo-thorax, which was furnished with anterior, marginal facetted eyes and central ocelli or smaller simple ones. to the ventral surface of the body were attached six pairs of appendages. the first pair are modified antennae with pincer-like terminations, used for prehensile purposes. then come four pairs of slender walking feet. the sixth pair of appendages is in the form of powerful swimming feet or paddles, at the bases of which are the comb-like jaws. the abdomen consists of thirteen joints, the last of which, the telson, is spatulate and posteriorly pointed. fragments of a tolerably large species of _pterygotus_ occur in the silurian shales of south yarra, melbourne, victoria. it was probably about inches in length when complete. of this form, known as _p. australis_ (fig. b), portions of the chelate (clawed) appendages, and parts of the abdominal segments have been found from time to time, but no complete fossil has yet been discovered. [illustration: =fig. --silurian eurypterids.= a--pterygotus osiliensis, schmidt. i. of oesel. (_after schmidt_) b--pterygotus australis, mccoy. part of a body-segment. silurian (melb.) victoria ] =jurassic insects.--= of the group of the _insecta_, the ipswich coal measures (jurassic) of queensland have yielded an interesting buprestid beetle (_mesostigmodera_), whilst beds of the same age in new south wales contain the remains of a probable _cicada_, associated with leaves of the fern _taeniopteris_. =lower cretaceous dragon-fly.--= from the lower cretaceous of the flinders river district, queensland, there has been obtained a fossil dragon-fly, _aeschna flindersensis_ (fig. d). =cainozoic insects.--= certain cainozoic beds of new south wales, of the age of the deep-leads of victoria, and probably equivalent to the kalimnan terrestrial series, contain a species of _cydnus_, a bug-like insect belonging to the order rhynchota; and there are in the same series a midge (_chironomus_), a day-fly (_ephemera_, fig. e) and several beetles (? _lagria_, _palaeolycus_, _cyphon_ and _oxytelus_). the occurrence of these insects of the deep-leads helps to complete the landscape picture of those far-off lower pliocene times, when the old river systems brought down large contributions of vegetable waste from higher lands, in the form of twigs with leaves and fruits; with occasional evidences of the rich and varied fauna of insect life which was especially promoted in the damp and vegetative areas of the lower lands. common or characteristic species of the foregoing chapter. trilobites. _ptychoparia howchini_, eth. fil. lower cambrian: south australia. _dolichometopus tatei_, h. woodward. lower cambrian: south australia. _olenellus browni_, eth. fil. lower cambrian: northern territory. _agnostus australiensis_, chapm. upper cambrian: victoria. _ptychoparia thielei_, chapm. upper cambrian: victoria. _dikellocephalus florentinensis_, eth. fil. upper cambrian: tasmania. _dinesus ida_, eth. fil. lower ordovician: victoria. _asaphus illarensis_, eth. fil. ordovician: central s. australia. _ampyx parvulus_, forbes, var. _jikaensis_, chapm. silurian (melbournian): victoria. _illaenus jutsoni_, chapm. silurian (melbournian): victoria. _proetus euryceps_, mccoy. silurian: victoria. _cyphaspis spryi_, gregory. silurian (melbournian): victoria. _bronteus enormis_, eth. fil. silurian (yeringian): victoria. _lichas australis_, mccoy. silurian (yeringian): victoria. _odontopleura jenkinsi_, eth. fil. silurian: new south wales. silurian (yeringian): victoria. _encrinurus punctatus_, brunnich sp. silurian: new south wales. silurian (yeringian): victoria. _encrinurus (cromus) murchisoni_, de koninck. silurian: new south wales. _encrinurus (cromus) spryi_, chapm. silurian (melbournian): victoria. _calymene blumenbachii_, brongn. silurian (wangapeka series): new zealand. _homalonotus expansus_, hector. silurian (wangapeka series): new zealand. _homalonotus knightii_, könig. silurian (wangapeka series): new zealand. _homalonotus harrisoni_, mccoy. silurian (melbournian): victoria. _homalonotus vomer_, chapm. silurian: victoria. _cheirurus insignis_, beyrich. silurian: new south wales. _phacops sweeti_, eth. fil. and mitch. silurian: new south wales. silurian (yeringian): victoria. _phacops serratus_, foerste. silurian (yeringian): victoria. silurian: new south wales. _dalmanites meridianus_, eth. fil. and mitch, sp. silurian: new south wales, victoria and tasmania. _cheirurus_ sp. middle devonian: victoria. _proetus_ sp. devonian: western australia. _phillipsia seminifera_, phillips. carbopermian: new south wales. _phillipsia grandis_, eth. fil. carbopermian: w. australia and queensland. _griffithides eichwaldi_, waldheim. carbopermian: new south wales and queensland. _brachymetopus strzelecki_, mccoy. carbopermian: new south wales. phyllopoda. _leaia mitchelli_, eth. fil. upper carboniferous: new south wales. _estheria coghlani_, cox. trias: new south wales. _estheria minuta_, alberti sp. trias: new zealand. _estheria mangaliensis_, jones. jurassic: queensland. ostracoda. _leperditia_ sp. lower cambrian: s. australia. _beyrichia kloedeni_, mccoy. silurian (yeringian): victoria. _beyrichia wooriyallockensis_, chapm. silurian (yeringian): victoria. _beyrichia maccoyiana_, jones, var. _australis_, chapm. silurian: (yeringian): victoria. _bythocypris hollii_, jones. silurian (yeringian): victoria. _macrocypris flexuosa_, chapm. silurian (yeringian) victoria. _primitia reticristata_, jones. silurian (yeringian): victoria. _leperditia shearsbii_, chapm. silurian: new south wales. _primitia cuneus_, chapm. middle devonian: victoria. _beyrichia varicosa_, t. r. jones. carboniferous: queensland. _primitia dunii_, chapm. carbopermian: new south wales. _jonesina etheridgei_, chapm. carbopermian: new south wales. _entomis jonesi_, de koninck. carbopermian: new south wales. _synaphe mesozoica_, chapm. sp. trias: new south wales. _cythere lobulata_, chapm. jurassic: w. australia. _paradoxorhyncha foveolata_, chapm. jurassic: w. australia. _loxoconcha jurassica_, chapm. jurassic: w. australia. _cytheropteron australiense_, chapm. jurassic: w. australia. _bairdia amygdaloides_, brady. cainozoic and living: victoria. _cythere senticosa_, baird. cainozoic. also living: victoria. _cythere clavigera_, g. s. brady. cainozoic and living: victoria. _cytherella punctata_, g. s. brady. cainozoic and living: victoria. _cytherella pulchra_, g. s. brady. cainozoic and living: victoria. cirripedia. _turrilepas mitchelli_, eth. fil. silurian: new south wales. _turrilepas yeringiae_, chapm. silurian (yeringian): victoria. _lepas pritchardi_, hall. cainozoic (janjukian): victoria. _(?) pollicipes aucklandicus_, hector sp. cainozoic (oamaru series): new zealand. _balanus_ sp. cainozoic (janjukian and kalimnan): victoria. phyllocarida. _rhinopterocaris maccoyi_, eth. fil. sp. lower ordovician: victoria. _hymenocaris hepburnensis_, chapm. l. ordovician: victoria. _caryocaris marri_, jones and woodw. l. ordovician: victoria and tasmania. _caryocaris angusta_, chapm. l. ordovician: victoria. _saccocaris tetragona_, chapm. l. ordovician: victoria. _ceratiocaris_ cf. _murchisoni_, agassiz sp. silurian: victoria. _ceratiocaris pinguis_, chapm. silurian (melbournian): victoria. _ceratiocaris pritchardi_, chapm. silurian: victoria. _aptychopsis victoriae_, chapm. silurian (melbournian): victoria. _dithyrocaris praecox_, chapm. silurian (melbournian): victoria. decapoda. _prosopon etheridgei_, h. woodw. lower cretaceous: queensland. _ommatocarcinus corioensis_, cresswell sp. cainozoic (janjukian): victoria. _ebalia_ sp. cainozoic (kalimnan): victoria. _harpactocarcinus tumidus_, h. woodw. cainozoic (oamaru series): new zealand. _thalassina emerii_, bell. (?) pleistocene: queensland and northern territory. eurypterida. _pterygotus australis_, mccoy. silurian (melbournian): victoria. insecta. _mesostigmodera typica_, etheridge fil. and olliff. jurassic: queensland. _(?) cicada lowei_, etheridge fil. and olliff. jurassic: new south wales. _aeschna flindersensis_, h. woodward. lower cretaceous: queensland. _chironomus venerabilis_, eth. fil. and oll. cainozoic: new south wales. _ephemera culleni_, eth. fil. and oll. cainozoic: new south wales. _palaeolycus problematicum_, eth. fil. and oll. cainozoic: new south wales. * * * * * literature. trilobites. mccoy, f. prod. pal. vict., dec. iii. , pp. - , pls. xxii. and xxiii. (silurian). hector, j. trans. n.z. inst., vol. ix. , p. , pl. xxvii. (_homalonotus_). woodward, h. geol. mag., dec. iii. vol. i. , pp. - , pl. xi. (cambrian). mitchell, j. proc. linn. soc. new south wales, vol. ii. , pp. - , pl. xi. (silurian). foerste, a. f. bull. sci. lab. denison univ., vol. iii. pt. v. , pp. - , pl. xiii. etheridge, r. jnr. proc. linn. soc. new south wales, vol. v. pp. - , pl. xviii. (_bronteus_). idem, parl. papers, leg. assemb. s.a., vol. i. no. , ; ibid., vol. , no. , (_asaphus_). id., geol. queensland, , pp. - , pls. vii. viii. and xliv. (carboniferous). id., proc. r. soc. vict., vol. vi. (n.s.), , pp. - , pl. xi. (_bronteus_). id., ibid, vol. viii. (n.s.), , pp. , , pl. i. (_dinesus_). id., rec. austr. mus., vol. v. no. , , pp. - , pl. x. (cambrian). id., trans. r. soc. s. austr., vol. xxii. , pp. - , pl. iv. (cambrian). etheridge, r. jnr. and mitchell, j. proc. linn. soc. new south wales, vol. vi. , pp. - , pl. xxv.; ibid., vol. viii. , pp. - , pls. vi. vii.; ibid., vol. x. , pp. - , pls. xxxviii.-xl.; ibid., vol. xxi. , pp. - , pls. l.-lv. tate, r. rep. horn exped., , part , palaeontology, pp. , , pl. iii. de koninck, l. g. mem. geol. surv. new south wales, pal. no. , , pp. - pl. i. (silurian); pp. - , pl. xxiv. (carboniferous). gregory, j. w. proc. r. soc. vict., vol. xiii. (n.s.) pt. ii, , pp. - , pl. xxii. (_cyphaspis_). ibid., vol. xv. (n.s.) pt. ii. , pp. - , pl. xxvi. (_dinesus_ and _notasaphus_.) chapman, f. proc. r. soc. vict., vol. xxiii. (n.s.), pt. ii. , pp. - , pls. lviii. and lix. (cambrian). ibid., vol. xxiv. (n.s.) pt. ii. , pp. - , pls. lxi.-lxiii. (silurian). phyllopoda. cox, j. c. proc. linn. soc. new south wales, vol. v., pt. , , p. (_estheria_). etheridge, r. jnr. ibid., vol. vii. , pp. - , text fig. (_leaia_). idem, mem. geol. surv. new south wales, pal. no. , , pp. - , pl. i. (_estheria_). ostracoda. brady, g. s. in etheridge, jnr. geol. mag., , p. (cainozoic). de koninck, l. g. mem. geol. surv. new south wales, pal. no. , , pp. , (silurian); ibid., pp. , , pl. xxiv. (carboniferous). chapman, f. proc. r. soc. vict., vol. xvi. (n.s.), pt. ii. , pp. - , pl. xxiii. (jurassic). idem, ibid., vol. xxii. (n.s.), pt. i. , pp. - , pl. i. (_leperditia_). idem, rec. geol. surv. new south wales, vol. viii. pt. , , pp. - , pl. liv. (triassic). idem, rec. geol. surv. vict., vol. iii. pt. , , p. , pl. xxxvi. (_primitia_). idem, proc. r. soc. vict., vol. xv. (n.s.), pt. ii. , pp. - , pl. xvi. (_beyrichia_). ibid., vol. xvii. (n.s.) pt. i. , pp. - , pls. xiii.-xvii. (silurian). cirripedia. etheridge, r. jnr. geol. mag., dec. iii. vol. vii. , pp. , , pl. xi. (_turrilepas_). hall, t.s. proc. r. soc. vict., vol. xv. (n.s.) pt. i. , pp. , , pl. xi. (_lepas_). benham, w. b. geol. mag., dec. iv. vol. x. pp. - , pls. ix. x. (_? pollicipes_). chapman, f. proc. r. soc. vict. vol. xxii. (n.s.) pt. ii. , pp. - , pls. xxviii. xxix. (_turrilepas_). phyllocarida. etheridge, r. jnr. rec. geol. surv. new south wales, vol. iii. pt. i. , pp. - , pl. iv. (ordovician). chapman, f. proc. r. soc. vict. vol. xv. (n.s.), pt. ii. , pp. - , pl. xviii. (ordovician); ibid., vol. xvii. (n.s.) pt. i. , pp. - , pl. xvii.; ibid., vol. xxii. (n.s.), pt. ii. , pp. - , pl. xxviii. (silurian). idem, rec. geol. surv. vict., vol. iii. pt. , , pp. , , pls. xvii. xviii. (ordovician). decapoda. bell, t. proc. geol. soc. lond., vol. i. , pp. , . text-fig. (_thalassina_). woodward, h. quart. journ. geol. soc., vol. xxxii. , pp. - , pl. vii. (_harpactocarcinus_). idem., proc. linn. soc. new south wales, vol. vii. ( ), pt. , , pp. - pl. iv. (_prosopon_). hall, t. s. proc. r. soc. vict., vol. xvii. (n.s.) pt. ii. , pp. - , pl. xxiii. (_ommatocarcinus_). eurypterida. mccoy, f. geol. mag. dec. iv. vol. vi. , pp. , , text fig. (_pterygotus_). insecta. woodward, h. geol. mag. dec. iii. vol. i. , pp. - , pl. xi. (_aeschna_). etheridge, r. jnr. and olliff, a. s. mem. geol. surv. new south wales, pal. no. , (mesozoic and cainozoic). chapter xii. fossil fishes, amphibians, reptiles, birds, and mammals. =vertebrates.--= the above-named classes of animals are distinguished from those previously dealt with, by the presence of a vertebral column. the vertebral axis may be either cartilaginous as in some fishes, or bony as in the greater number of animals belonging to this sub-kingdom. =chordata.--= _links between the invertebrates and fishes._--the curious little ascidians or "sea-squirts," belonging to the group tunicata, are held by some authorities to be the degenerate descendants of a free-swimming animal having a complete notochord and nerve-tube, structures which are now only seen in the tails of their tadpole-like larvae. the fully developed tunicate is generally sessile and provided with a thick outer coat (tunic) and muscular inner lining. this outer coat in some forms, as _leptoclinum_, is strengthened with tiny calcareous spicules, and these are sometimes found in the fossil state in cainozoic clays, as well as in some of the calcareous deep-sea oozes. the little stellate spicules of _leptoclinum_ are abundant in the balcombian clays of mornington, victoria. another primitive form with a notochord is the lancelet, but this, having no hard parts, is not found in the fossil state. =primitive types of fishes.--= _fishes._--the remains of fishes are naturally more abundant in the fossil condition, owing to their aquatic habits, than those of other vertebrates. the earliest fishes were probably entirely cartilaginous, and some have left only a mere trace or impression on the rocks in which they were embedded. these primitive fishes have no lower jaw, and are without paired limbs. they are sometimes placed in a class by themselves (_agnatha_). the orders of this primitive fish series as represented in australasia are the osteostraci ("bony shells"), of which the remains of the _cephalaspis_-like head-shield of _thyestes_ has been found in the silurian of n.e. gippsland, victoria (fig. ); and the antiarchi, with its many-plated cuirass, armoured body-appendages, internal bony tissue, and coarsely tuberculated exterior, as seen in _asterolepis australis_, a fossil occasionally found in the middle devonian limestone of buchan, gippsland. =true fishes.--devonian.--= of the true fishes (pisces), the elasmobranchii ("slit-gills"), a sub-class to which the modern sharks belong, are represented in the devonian series by the paired spines of a form resembling _climatius_, found both in victoria and new south wales. remains of dipnoi ("double-breather" or lung-fishes) occur in the devonian of barker gorge, western australia, represented by a new species allied to _coccosteus_ ("berry-bone" fish); and in a bed of the same age at the murrumbidgee river, new south wales by the cranial buckler of _ganorhynchus süssmilchi_. [illustration: =fig. --incomplete head-shield= of thyestes magnificus, chapm. from the silurian (yeringian) of wombat creek, n.e. gippsland. / nat. size] [illustration: =fig. = =gyracanthides murrayi=, a. s. woodw. l. carboniferous. mansfield, victoria. (restoration). about / nat. size] [illustration: =fig. --teeth and scales of palaeozoic and mesozoic fishes.= a--strepsodus decipiens, a. s. woodw. l. carboniferous. victoria b--elonichthys sweeti, a. s. woodw. l. carboniferous. victoria c--corax australis, chapm. l. cretaceous. queensland d--belouostomus sweeti, eth. fil. and woodw. l. cretaceous. q. ] =carboniferous fishes.--= the lower carboniferous sandstone of burnt creek and other localities near mansfield, victoria, contains an abundant fish fauna, associated with stems of _lepidodendron_. the slabs of sandstone are often ripple-marked and show signs of tracks and castings of shore-living animals. these deposits were probably laid down in shallow water at the shore margin or in salt lagoons or brackish areas skirting the coast, into which at intervals the remains of the giant lycopods were drifted. the more important of these fish remains are elasmobranchs, as _gyracanthides murrayi_ (fig. ) and _acanthodes australis_; the dipnoan, _ctenodus breviceps_; a rhizodont or fringe-finned ganoid, _strepsodus decipiens_ (fig. a); and a genus related to _palaeoniscus_, _elonichthys_ (_e. sweeti_, fig. b, and _e. gibbus_). the defence spines of _gyracanthides_ are fairly abundant in the sandstones; whilst on some slabs the large enamelled scales of _strepsodus_ are equally conspicuous. from the sandstones of the same age, lower carboniferous, in the grampians of western victoria, some small but well-preserved spines belonging to the genus _physonemus_ have been found associated with a new variety of the well-known european carboniferous brachiopod, _lingula squamiformis_ (var. _borungensis_). =carbopermian fishes.--= in the carbopermian (gympie beds) of the rockhampton district, queensland, a tooth of a cochliodont ("snail tooth") occurs, which has been doubtfully referred to the genus _deltodus_ (? _d. australis_). the cochliodontidae show dentition remarkably like that of the _cestracion_ or port jackson shark. another tooth having the same family relationship has been referred to _tomodus ? convexus_, agassiz; this is from the carbopermian of the port stephen district of new south wales. from the newcastle coal measures in new south wales a _palaeoniscus_-like fish, _urosthenes australis_ has been described. carbopermian fish remains are rare in western australia. they comprise a wrinkled tooth of _edestus_ (_e. davisii_) from the gascoyne river, belonging to a fish closely related to the port jackson shark; and a cochliodont, _poecilodus_ (_p. jonesi_, ag.) from the kimberley district. =triassic fishes.--= fossil fishes are important and numerous in australian triassic beds, especially in new south wales. at the base of the hawkesbury or close of the narrabeen series, the railway ballast quarry near gosford has yielded an extensive and extremely interesting collection. near the floor of the quarry there is a band of sandy shale and laminated sandstone feet inches in thickness, and this contains the following genera:--a dipnoan, _gosfordia_; and the following ganoids or enamelled scale fishes--_myriolepis_, _apateolepis_, _dictyopyge_, _belonorhynchus_, _semionotus_, _pristisomus_ (see _antea_, fig. ), _cleithrolepis_ (fig. ), _pholidophorus_ and ? _peltopleurus_. =upper triassic fishes.--= in the middle of the wianamatta or upper trias series at st. peter's, near sydney, which contains a fauna described as slightly older in aspect than that of gosford, having carbopermian affinities, there occur in the hard shale or clay stone the genera _pleuracanthus_ (a palaeozoic shark); _sagenodus_ (a dipnoan related to _ctenodus_ of the victorian carboniferous); and the following ganoids,--_palaeoniscus_, _elonichthys_, _myriolepis_, _elpisopholis_, _platysomus_ and _acentrophorus_. from the soft shales were obtained _palaeoniscus_, _semionotus_, _cleithrolepis_ and _pholidophorus_; an assemblage of genera somewhat comparable with the gosford fauna. [illustration: =fig. --cleithrolepis granulatus, egerton.= triassic (hawkesbury series). gosford, new south wales. / nat. size. (_after smith woodward_.) ] =lower mesozoic fishes.--= from the lower mesozoic sandstone (?triassic) of tasmania, two species of _acrolepis_ have been described, viz., _a. hamiltoni_ and _a. tasmanicus_. the former occurs in the thick bed of sandstone, of nearly , feet, at knocklofty; the latter species in the sandstone with _vertebraria_ conformably overlying the carbopermian at tinderbox bay. [illustration: =fig. --remains of jurassic and other vertebrates.= --ceratodus avus, a. s. woodw. left splenial with lower tooth. cape paterson, victoria. about / nat. size --ceratodus forsteri, krefft. left lower tooth. living. queensland. about / nat. size --phalangeal of carnivorous dinosaur. cape paterson. about / nat. size --phalangeal of megalosaurian. wealden, sussex, england. / nat. size ] =jurassic fishes.--= the jurassic beds of victoria contain three genera. _psilichthys selwyni_, a doubtful palaeoniscid was described from carapook, co. dundas; whilst _leptolepis_, a genus found in the trias of new south wales and the lias and oolite of europe, is represented by _l. crassicauda_ from casterton, associated with the typical jurassic fern, _taeniopteris_. in the jurassic beds of south gippsland, at cape paterson, an interesting splenial tooth of the mudfish, _ceratodus_, was found, named _c. avus_ (fig. ). since then, in a bore-core from kirrak near the same place a fish scale was discovered (fig. ) which, by its shape, size and structure seems to differ in no way from the living lung-fish of queensland (fig. ). it is reasonable to infer that tooth and scale belong to the same species; and in view of the close relationship of the tooth with that of the living mudfish, rather than with that of the _ceratodus_ found fossil in the mesozoic of europe, it may be referred to _neoceratodus_, in which genus the living species is now placed. [illustration: =fig. --scale of ceratodus (neoceratodus)= (?)avus, a. s. woodw. jurassic. kirrak, s. gippsland, victoria. about nat. size] [illustration: =fig. --the queensland lung-fish= or barramunda (neoceratodus forsteri). about / th. nat. size (_after lydekker, in warne's natural history_) ] [illustration: =fig. --leptolepis gregarius=, a. s. woodw. talbragar series, jurassic. talbragar river, new south wales / nat. size] from the jurassic beds (talbragar series) of new south wales, an interesting collection of ganoid fishes has been described, comprising _coccolepis australis_, _aphnelepis australis_, _aetheolepis mirabilis_, _archaeomaene tenuis_, _a. robustus_, _leptolepis talbragarensis_, _l. lowei_ and _l. gregarina_ (fig. ). =lower cretaceous fishes.--= fish remains are fairly abundant in the lower cretaceous of queensland. they comprise both the sharks and the ganoids. of the sharks, a specimen, showing seven conjoined vertebrae has been named _lamna daviesii_, from the richmond downs, flinders river district; and a tooth referred to _lamna appendiculatus_, agassiz, from kamileroy, leichhardt river, n.w. queensland. the typical cretaceous genus _corax_ is represented by a small tooth named _c. australis_ (fig. c), from the hamilton river, queensland, and which closely approaches the tooth of _corax affinis_, agassiz, from the upper cretaceous of europe. of the ganoid fishes two genera, both members of the family _aspidorhynchidae_, have been found in queensland. _aspidorhynchus_ sp. and _belonostomus sweeti_ (fig. d) have both occurred at hughenden, flinders river district. the former genus has a slender body and produced rostrum; in europe it is more characteristic of jurassic strata. _belonostomus_ ranges from the upper oolite, bavaria, to the upper cretaceous in other parts of the world. remains of a species of _portheus_, one of the predaceous fishes which lived in the cretaceous period, consisting of a portion of the cranium with the anterior part of the jaws, has been obtained from the rolling downs formation (lower cretaceous) near hughenden, queensland. =cretaceous fishes, new zealand.--= [illustration: =fig. --cretaceous and cainozoic fish-teeth.= a--notidanus marginalis, davis. cainozoic. new zealand b--callorhynchus hectori, newton. cainozoic. new zealand c--oxyrhina hastalis, ag. cainozoic. victoria d--lamna apiculata, ag. cainozoic. victoria e--carcharodon auriculatus, blainv. sp. cainozoic. victoria f--sargus laticonus, davis. cainozoic. new zealand ] the cretaceous beds of new zealand are grouped in ascending order as the waipara greensands, the amuri limestone and the weka pass stone. in the waipara beds occur the teeth of _notidanus marginalis_ (fig. a), and _n. dentatus_. in the amuri limestone _n. dentatus_ is again found, as well as the genus _lamna_, represented by _l. compressa_, ag. (originally described as _l. marginalis_, davis), _l. carinata_ and _l. hectori_. two forms of "elephant fish" are represented by their dental plates, namely _callorhynchus hectori_ (fig. b) and _ischyodus thurmanni_, pictet and campiche (recorded as _i. brevirostris_, ag.). =cainozoic fishes.--= fish remains principally consisting of teeth, are common fossils in the cainozoic beds of southern australia, particularly in victoria, and also in new zealand. =balcombian series, southern australia.--= the balcombian beds as seen at mornington and in the lower beds at muddy creek, hamilton, contain the teeth of sharks as _odontaspis contortidens_, _lamna crassidens_, _l. apiculata_, _oxyrhina hastalis_ (rarely), _o. minuta_, _carcharodon megalodon_, and _c. robustus_. =janjukian.--= the janjukian series (miocene), represented at torquay, waurn ponds and table cape, contains an abundant fish fauna, including amongst sharks, _cestracion cainozoicus_, _asteracanthus eocaenicus_, _galeocerdo davisi_, _carcharoides totuserratus_, _odontaspis contortidens_, _o. incurva_, _o. cuspidata_, _lamna crassidens_, _l. apiculata_ (fig. d), _l. compressa_, _l. bronni_, _oxyrhina hastalis_ (occasional) (fig. c), _o. desori_, _o. retroflexa_, _o. minuta_, _carcharodon auriculatus_ (fig. e), _c. megalodon_ and _c. robustus_. a species of chimaeroid or elephant fish is represented by a left mandibular tooth named _ischyodus mortoni_, from the table cape beds, tasmania. the corio bay series contains teeth of _acanthias geelongensis_, _sphyrna prisca_, _odontaspis contortidens_, _o. attenuata_, _oxyrhina minuta_, _carcharodon megalodon_, amongst sharks; whilst the spine of a porcupine fish, _diodon connewarrensis_ has been obtained from the clays of lake connewarre, victoria. =kalimnan.--= [illustration: =fig. --cainozoic fish remains.= a--carcharoides tenuidens, chapm. cainozoic (janj.) victoria b--odontaspis contortidens. agassiz. cainozoic (kal.) victoria c--galeocerdo latidens, agassiz. cainozoic (kal.) victoria d--myliobatis morrabbinensis, chapm. and pritch. cainozoic (kal.) victoria e--labrodon confertidens. chapm. and pritch. cainozoic (kal.) vict. f--diodon formosus, chapm. and pritch. cainozoic (kal.) vict. ] the kalimnan series is also prolific in the remains of fishes, the principal localities being beaumaris and grange burn, hamilton. amongst the sharks there found are, _notidanus jenningsi_ (related to the indian grey shark), _cestracion cainozoicus_ (related to the port jackson shark), _asteracanthus eocaenicus_, _galeocerdo davisi_, _g. latidens_ (fig. c), _g. aduncus_, _odontaspis contortidens_ (fig. b), _o. incurva_, _o. cuspidata_, _o. attenuata_, _lamna apiculata_, _l. compressa_, _oxyrhina hastalis_ (abundant), _o. desori_, _o. retroflexa_, _o. eocaena_, _o. minuta_, _carcharodon auriculatus_ and _c. megalodon_. an extinct species of sting ray, _myliobatis moorabbinensis_ (fig. d), is found at beaumaris, represented by occasional palatal teeth. mandibular and palatine teeth of an extinct genus of elephant fish, _edaphodon_ (_e. sweeti_) are occasionally found at beaumaris, and at grange burn near hamilton. two extinct forms of the wrasse family, the labridae, are found in victoria; the pharyngeals of _labrodon confertidens_ (fig. e), occurring at grange burn, hamilton, and those of _l. depressus_, at beaumaris. the palatal jaws of a porcupine fish, _diodon formosus_ (fig. f), are frequently met with at the base of the kalimnan series, both at grange burn and beaumaris. =oamaru series, new zealand.--= in new zealand the oamaru series, which is comparable in age with the victorian janjukian, contains numerous fish remains, chiefly teeth of sharks. these are: _notidanus primigenius_, _n. marginalis_ (also occurring in the waipara series), _galeocerdo davisi_, _odontaspis incurva_, _o. cuspidata_, _o. attenuata_, _lamna apiculata_, _l. compressa_, _oxyrhina retroflexa_, _carcharodon auriculatus_, _c. megalodon_ and _c. robustus_. the teeth of a sting ray, _myliobatis plicatilis_ and of a species of sea-bream, _sargus laticonus_, also occur in this series (fig. f). =pleistocene.--= a species of fish belonging to the family of the perches, _ctenolates avus_, has been described from freshwater carbonaceous shale of pleistocene age from nimbin on the richmond river, new south wales. =amphibians: their structure.--= _amphibians._--this group includes amongst living forms the frogs, toads, newts, and salamanders. the remains of amphibia are rare in australasian rocks, and practically limited to the group of the triassic labyrinthodonts. the amphibia are distinguished from reptiles by certain changes which their young undergo after leaving the egg. in this intermediate stage they breathe by external gills, these being sometimes retained together with the internal lungs in the adult stage. in the older forms of this group the vertebra is of the nature of a notochord, the joints consisting of a thin bony ring with a gelatinous interior. the labyrinthodontia have a long, lizard-like body, short pectoral limbs as compared with the pelvic, and five-toed feet. the skull is completely roofed over. the teeth are pointed, with a large pulp cavity and wall of infolded or plicated dentine (hence the name labyrinthodont--maze-tooth). the vertebrae are hollow on both sides, sometimes imperfectly ossified, and with a notochordal canal. ventral aspect with bony thoracic plates. cranial bones deeply sculptured, and carrying mucus canals. =carbopermian labyrinthodonts.--= the genus _bothriceps_, probably an archegosaurian, is represented by two species, _b. australis_ and _b. major_ from new south wales (fig. ). the latter species occurs in the oil shale (carbopermian) of airly. [illustration: =fig. --bothriceps major, a. s. woodward.= carbopermian. new south wales. about / th. nat. size (_after a. s. woodward_). ] =triassic labyrinthodonts.--= from the hawkesbury series near gosford, new south wales, the labyrinthodont, _platyceps wilkinsoni_ has been described. the skeleton is nearly complete and exposed on the ventral face; the head is mm. long and mm. broad. this specimen is associated with the remains of ganoid fishes, as _palaeoniscus_ and _cleithrolepis_, together with the equisetum-like plant _phyllotheca_. other, somewhat doubtful remains having similar affinities to the labyrinthodonts are also recorded from the wianamatta beds (upper trias) at bowral, new south wales, consisting of a maxilla with teeth and vertebrae with ribs of the left side. remains of a labyrinthodont, _biloela_, supposed to be related to _mastodonsaurus_, have been recorded from the hawkesbury series of cockatoo island, port jackson, new south wales, by w. j. stephens, and consisting of a pectoral plate compared by that author with _m. robustus_ (now transferred to the genus _capitosaurus_). the only other recorded remains of this group in australasia are those noted by w. j. stephens from the kaihiku series (trias) at nugget point, otago; and in the otapiri series (upper trias) of the wairoa district, new zealand. =reptilia: their structure.--= _reptilia._--the reptiles are cold-blooded, vertebrated animals, with a scaly skin or armour. their respiration is essentially by means of lungs, and they are terrestrial or aquatic in habit. the skeleton is completely ossified (bony). reptiles, although resembling amphibians externally, are more differentiated in structure and of generally larger proportions. they exhibit great diversity of form, especially as regards their extremities. they were even adapted for flying, as in the pterosaurs ("flying dragons") with their membranous wing attached to the anterior limb. the deinosaurs ("terrible reptiles") were often of great size, exceeding the dimensions of any land mammals, and their limbs were adapted for walking. the marine reptiles, as the ichthyosauria ("fish-lizards") and sauropterygia ("lizard-finned") had the limbs transformed into paddles. the neural spines in the vertebra of the turtles are laterally expanded into a carapace and united with dermal plates. the vertebrae of reptilia show great variation of form, being biplanate (amphiplatyan), biconcave (amphicoelus), hollow in front (procoelus), or hollow at the back (opisthocoelus). in the case of reptiles having both pairs of limbs developed, the cervical, dorsal, sacral and caudal regions may be separately distinguished. amongst the ophidia (snakes), pythonomorpha ("sea-lizards") and ichthyosaurs ("fish-lizards") there is no differentiated sacral region. the skull of the reptiles is nearer that of birds than amphibians. the basiocciput (basal bone of the skull at the back) articulates with the atlas (top joint of the backbone) by means of a single condyle (protuberance). all reptiles, with the exception of the chelonians (turtles), and a few others, are furnished with teeth: these are formed chiefly of dentine with a layer of enamel. =dentition.--= some teeth have solid crowns (pleodont); some grow from persistent pulps (coelodont); socketed teeth (thecodont) are inserted in alveoli; some are fused with the supporting bone along the outer rim or top (acrodont); whilst others are developed laterally along the flange-like inner rim of the jaw (pleurodont). =permian and triassic reptiles.--= the history of reptilia commences in permian and triassic times, when they were notably represented by the theromorphs, _pareiasaurus_ and _tritylodon_ in south africa; the proterosauria of the european and american permian and trias, represented by the lizard-like _palaeohatteria_ and the dorsally frilled _dimetrodon_, with its formidable array of neural spines; also the rhynchosauria, with their beak-like jaws of the same formations. these two groups constitute the order rhynchocephalia, which is represented at the present day by the tuatera of new zealand. =triassic reptile, new zealand.--= the earliest australian reptilian record is that of a vertebra of _ichthyosaurus_ from the kaihiku series of mount potts, new zealand (triassic). this specimen was named _i. australis_ by hector, but since that species name was preoccupied by mccoy in it is suggested here that the new zealand species should be distinguished as _i. hectori_. the new zealand occurrence of _ichthyosaurus_ makes the geological history of the genus very ancient in this part of the world. =jurassic reptiles.--= at cape paterson, victoria, in the jurassic coal-bearing sandstone an extremely interesting discovery was made a few years ago, of the ungual bone (claw) of a carnivorous deinosaur, probably related to _megalosaurus_ of the european jurassic and cretaceous beds (see fig. , , a). the presence of an animal like this in australia points to the former existence of a concomitant terrestrial animal fauna, upon which the deinosaur must have preyed. [illustration: =fig. --ichthyosaurus australis, mccoy.= a--part of head, showing eye protected by sclerotic plates b--left pectoral paddle. l. cretaceous. flinders river, queensland. / nat. size (_nat. mus. coll._) ] =lower cretaceous reptiles.--= the rolling downs formation (lower cretaceous) of the thompson and flinders rivers in queensland has yielded remains of a tortoise, _notochelone costata_ (see _antea_, fig. ); and the interesting fish-lizard _ichthyosaurus_. numerous and well preserved remains of _i. australis_ mccoy come from the flinders river (fig. ); whilst _i. marathonensis_ is recorded from marathon station, queensland. the former species is typically represented by a nearly complete skeleton, and was considered by mccoy to be one of the largest examples of the genus, since a perfect specimen would probably reach the length of feet. its teeth resemble those of _i. campylodon_, carter, from the english chalk. of the sauropterygia two species of _pliosaurus_ (_p. macrospondylus_ and _p. sutherlandi_) have been described from the lower cretaceous of the flinders river; whilst the latter species has also occurred at pitchery creek, central queensland and at marathon. _p. macrospondylus_ is distinguished from _p. sutherlandi_ by the roughened edges of the vertebral centra. another genus of the "lizard-finned" reptiles (sauropterygia), viz., _cimoliosaurus_, occurs in the upper cretaceous of white cliffs, new south wales (fig. b, c.) [illustration: =fig. --fossil reptiles.= a--taniwhasaurus oweni. hector. (lower jaw). cretaceous. new zealand b--cimoliosaurus leucoscopelus, eth. fil. (teeth). up. cretaceous. new south wales c--cimoliosaurus leucoscopelus, eth. fil. (phalangeal). up. cretaceous. new south wales d--miolania oweni, a. s. woodw. pleistocene. queensland ] =cretaceous reptiles, new zealand.--= the waipara series (cretaceous) of new zealand contains a fairly large number of reptilian species belonging to several genera among which may be mentioned _plesiosaurus_, _polycotylus_, and _cimoliosaurus_ among the sauropterygia; and _tylosaurus_ and _taniwhasaurus_ (fig. a), marine lizard-like reptiles, belonging to the sub-order pythonomopha. =cainozoic and pleistocene reptiles.--= the later cainozoic deposits of queensland contain remains of crocodiles referred to _pallymnarchus pollens_ (from maryvale creek) and _crocodilus porosus_ (from chinchilla and arcola, near brisbane, queensland). the former species has also occurred at clunes, whilst _crocodilus porosus_ is recorded from the loddon valley, both in victoria. another late tertiary reptile is the remarkable horned turtle, _miolania oweni_, which is found in queensland in pleistocene deposits (fig. d), and in the pliocene (deep leads) of gulgong, new south wales; whilst a second species of the same genus, _m. platyceps_, is found in coral sand at lord howe island, miles distant from australia. this genus has a skull with large bony protuberances, giving it a horned appearance, and the tail is encased in a bony sheath. a species of _miolania_ is also described from patagonia. the cave deposits of wellington valley, new south wales, as well as the fluviatile deposits of queensland, have, yielded the bones of several genera of lizards, including the giant lizard (_megalania_), which, in its length of feet exceeded that of most living crocodiles. =birds.--= _birds (aves)._--these warm-blooded animals are closely related to reptiles in many essential particulars; and are generally considered to more nearly approach the deinosaurs than any other group. the ratitae ("raft-breasted" or keel-less birds) and carinatae (with keeled breast-bones), a sub-class including most modern birds, were probably differentiated before the cainozoic period. =jurassic bird.--= the oldest recorded bird, the remarkable _archaeopteryx_, of the upper jurassic of bavaria in europe, belonging to the saururae (reptilian-tailed) is, so far, restricted to the beds of that age. =miocene bird, new zealand.--= the earliest known birds in australasia occur in the miocene rocks (oamaru series), of new zealand. in this series, in the marawhenua greensands, a giant penguin, _palaeeudyptes antarcticus_ is found at kakanui near oamaru, at curiosity shop near christchurch and at brighton near nelson, new zealand: this interesting occurrence shows that these restricted antarctic birds had already become an established type as early as the miocene. =victorian cainozoic bird.--= the impression of a bird's feather, probably of a wader, has lately been described from western victoria (see _antea_ fig. and fig. ). this occurs in ironstone, on the surface of which are also impressions of gum (_eucalyptus_) and native honeysuckle (_banksia_) leaves, of species closely related to those now growing in the same locality. this ironstone is probably of janjukian age, and may therefore be coincident with the new zealand occurrence of the _palaeeudyptes_ in the oamaru series. =pliocene moa, new zealand.--= in the wanganui system (pliocene) the putiki beds have yielded bones of a small moa (_dinornis_), probably the oldest example of the group of great flightless birds which later predominated in new zealand. [illustration: =fig. --impression of bird's feather in ironstone.= wannon river, victoria. (enlarged).] =pleistocene struthious birds, australia.--= bones of a struthious or ostrich-like bird, described by owen under the name of _dromornis australis_, a bird as large as the moa, have been recorded from the pleistocene of peak downs and the paroo river, queensland. indeterminate species of the same genera occur in phillip co., new south wales, and the mount gambier caves, south australia; whilst _dromaeus patricius_ is known from king's creek, darling downs, queensland. _genyornis newtoni_ is an extinct bird allied to the emeus; it has been found in pleistocene deposits at lake callabonna, south australia, and other fragmentary remains have been identified by dr. stirling and mr. zietz from mount gambier and queensland. regarding the build and habits of _genyornis_, those authors remark that "its legs combine a huge femur nearly as massive, in all but length, as that of _dinornis maximus_, and a tibia equalling that of _pachyornis elephantopus_ with the relatively slender metatarse of _dinornis novae-zealandiae_ (_ingens_) and toes which are insignificant beside those of any of the larger moas."... "in height it may be confidently stated to have been from feet to feet inches, that is if the neck should have been of proportions similar to those of _pachyornis elephantopus_." those authors also attribute a slow, sluggish habit to the bird, and suggest that herbage rather than roots formed its food. it is very probable that the footprints of birds found in the older dune rock of warrnambool, victoria, associated with the doubtful "human footprints" may have been made by _genyornis_ or a related form. an extinct emu, _dromaeus minor_, has lately been described from the sub-recent deposits in king island, bass strait. =pleistocene carinate birds, australia.--= many genera of carinate birds belonging to living australian types have been identified by de vis from the fluviatile deposits on the darling downs, queensland. these include falcons (_taphaetus_ and _necrastur)_; a pelican (_pelicanus_); an ibis (_palaeopelargus_); a spoonbill (_platalea_); ducks (_anas_, _dendrocygna_, _biziura_ and _nyroca_); a darter (_plotus_); a pigeon (_lithophaps_); a ground-pigeon (_progura_); a mound-builder (_chosornis_); a rail (_porphyrio_); moor-hens (_gallinula_, _tribonyx_ and _fulica_); and a stork (_xenorhynchus_). =pleistocene and holocene birds, new zealand.--= in new zealand numerous remains of birds are found, chiefly in the pleistocene strata, associated with moa bones: such are _cnemiornis_, the flightless pigeon goose (fig. ); _harpagornis_, a predatory hawk-like bird larger than any existing eagle; and _aptornis_, an extinct rail. the sand-dunes, peat bogs, swamps, river alluvium, caves and rock shelters of new zealand often contain numerous remains of the gigantic moa birds included in the genera _dinornis_, _pachyornis_ and _anomalopteryx_, of which perhaps the best known are _d. giganteus_, _d. maximus_ (fig. ), _d. robustus_, _p. elephantopus_ (fig. ), and _a. antiqua_. some of the species have become so recently extinct that remains of their skin and feathers have been preserved in fissures in the rocks where they were shielded from the influence of air and moisture. the remains of moa birds are very abundant in some of the localities as at hamilton in southland, where, as hutton estimated, the remains of at least birds were contained within a radius of feet. [illustration: =fig. --cnemiornis calcitrans, owen.= pleistocene. new zealand. / th. nat. size (_after owen_). ] [illustration:=fig. --dinornis maximus, owen. (great moa).= pleistocene and holocene. new zealand. vertical height, ft. measured along spine, ft. in. (_nat. mus. coll._) ] [illustration: =fig. --pachyornis elephantopus, owen sp.= pleistocene. new zealand. about / th. nat. size. (_after owen_). ] =mammalia: early types.--= _mammalia._--the history of those warm-blooded animals, the mammals, commences in the early part of the mesozoic period. it was then that the skull began to assume the characters seen in the modern quadrupeds, and their well-formed limb-bones, and fusion of the three bones on each side of the pelvic arch to form the innominate bone, also show relationship to the later types. the earliest ancestral mammalian forms seem to be related to the theromorphic reptiles, predominant in the permian and trias. the mammals first to make their appearance were probably related to those of the monotreme and marsupial orders. more nearly related to the former is the group of mammals of the mesozoic period, the multituberculata. =multituberculata.--= this group comprises the triassic _tritylodon_ (south africa and germany); the upper jurassic _bolodon_ (england and united states); the upper jurassic to lower cainozoic _plagiaulax_ (england, united states and france); and the lower eocene _polymastodon_ (new mexico). the molar teeth are ridged longitudinally, and carry numerous tubercles, hence the name of the group, and resemble the deciduous teeth of the duck-billed platypus (_ornithorhynchus_). =monotremata.--= the monotremata are represented at the present day in australia and new guinea by the _echidna_ or spiny anteater, and by the _ornithorhynchus_ or duck-billed platypus of eastern australia and tasmania. these egg-laying mammals show relationship towards the reptiles both in structure and in methods of reproduction. a pliocene species of _ornithorhynchus_ (_o. maximus_) has been recorded from the deep-leads of gulgong, new south wales, and the same beds have yielded the remains of _echidna (proechidna) robusta_. remains of another species, _echidna, (p.) oweni_, have been described from the pleistocene cave-breccias of the wellington valley caves, new south wales; and _ornithorhynchus agilis_ is found in deposits of similar age in queensland. =marsupials.--= the marsupials or pouched mammals belong to the sub-class metatheria. they are divided into diprotodontia and polyprotodontia, accordingly as they possess a single pair of incisor teeth in the lower jaw, or many front teeth, hence the names of the two sub-orders. a later classification of the marsupials is that of their division into syndactyla and diadactyla. the diadactyla have the second and third toes separate, and are represented by the family dasyuridae or native cats. these are polyprotodont. they are the most archaic of the marsupial group. remains of _dasyurus_, both of extinct and still living species are found in pleistocene cave-breccias in victoria and new south wales. the tasmanian devil (_sarcophilus ursinus_) (fig. , ) and the tasmanian wolf (_thylacinus cynocephalus_), still living in tasmania, have left numerous remains on the mainland, in victoria and new south wales. of the latter genus an extinct species is _t. major_ from the pleistocene of queensland (fig. ). [illustration: =fig. = =skeleton of sarcophilus ursinus, harris sp. (tasmanian devil).= (_f. j. moore, prep._) ] [illustration: =fig. = =skull of sarcophilus ursinus, harris sp. (tasmanian devil).= pleistocene. queenscliff, victoria. about / nat. size (_after mccoy_). ] the syndactyla have the second and third toes enclosed in a common skin. the peramelidae and the notoryctidae are polyprotodont. the remainder are all diprotodont. the peramelidae or bandicoot family are represented in pleistocene cave-breccias in new south wales by the genera _peragale_ and _perameles_. [illustration: =fig. --thylacinus major, owen.= hind part of mandible, outer side. pleistocene. queensland. / nat. size] =pleistocene diprotodonts.--= pleistocene remains of the diprotodont forms of this syndactylous group are _phascolomys_ (the wombat), perhaps ranging as low as upper pliocene (_p. pliocenus_) (fig. ); _phascolonus (p. gigas)_ (fig. a)[ ], a large wombat from queensland and new south wales and south australia; the giant kangaroos, as _macropus titan_ (queensland, new south wales, victoria and south australia), _procoptodon goliah_ (queensland, new south wales and victoria), _sthenurus atlas_ (new south wales, queensland, victoria and south australia), _palorchestes azael_ (victoria, new south wales and queensland); also the great _diprotodon_, the largest known marsupial, as large as, and rather taller than, a rhinoceros, found in almost every part of australia, with an allied form referred to _nototherium_ occurring also in tasmania (figs. , , ). _nototherium_ (queensland, south australia and victoria), was a smaller animal than _diprotodon_, with a shorter and broader skull and similar dentition. remains of the extinct "marsupial lion," _thylacoleo carnifex_, an animal allied to the phalangers, have been found in cave-deposits in new south wales, queensland, victoria and western australia. incised bones of other animals, which are believed to have been gnawed by _thylacoleo_, have been found associated with its remains. _thylacoleo_ possessed a peculiar dentition, the first pair of incisors in the upper jaw being very large and trenchant, whilst the canine and two anterior premolars are small and functionless: the lower jaw has also a pair of large first incisors, behind which are two small premolars, and an enormous chisel-edged last premolar biting against a similar tooth in the upper jaw (fig. ). [footnote : this genus was described by owen in as a sub-genus of _phascolomys_ founded on some cheek-teeth; and subsequently, in , the same author described some incisors under the name of _sceparnodon ramsayi_, which are now known to belong to the same animal that bore the cheek-teeth.] [illustration: =fig. --mandible of phascolomys pliocenus, mccoy.= (?) upper pliocene ("gold cement.") dunolly, vict. about / nat. size. (_after mccoy_). ] [illustration: =fig. --cainozoic teeth and otolith.= a--phascolonus gigas, owen. (molar). pleistocene. queensland b--parasqualodon wilkinsoni, mccoy. (molar). cainozoic (janj.) vict. c--parasqualodon wilkinsoni, mccoy. (incisor). cainozoic (janj.) vict. d--metasqualodon harwoodi, sanger sp. (molar). cainozoic (janj.) south australia e--kekenodon onamata, hector. (molar). cainozoic (oamaruian). new zealand f--cetotolithes nelsoni, mccoy. (tympanic bone). cainozoic (janj.) victoria ] [illustration: =fig. --diprotodon australis, owen.= pleistocene. south australia. (_after stirling and zeitz_). ] [illustration: =fig. --upper surface of the right hind foot of diprotodon australis=. a--with the astragalus (ankle-bone) in position. b-- " " " " removed. cir. / nat. size.] [illustration: =fig. --diprotodon australis, owen. (restored).= from a sketch by c. h. angas.] [illustration: =fig. --thylacoleo carnifex, owen.= right lateral aspect of skull and mandible. pleistocene. australia. / th nat. size. c, canine. i, incisors. m, molars. pm, premolars. ] [illustration: =fig. --wynyardia bassiana, spencer.= upper cainozoic (turritella bed). table cape. tasmania. / th nat. size. (_casts in nat. mus. coll._) ] =oldest known marsupial.= the oldest marsupial found in australia is probably _wynyardia bassiana_ (fig. ), whose remains occurred in the _turritella_-bed at table cape, which is either of miocene or lower pliocene age. this stratum occurs above the well-known _crassatellites_-bed (miocene) of that locality. so far as can be gathered from its incomplete dentition, _wynyardia_ represents an annectant form between the diprotodonts and the polyprotodonts. =pleistocene genera, also living.--= besides the genera above enumerated, many other marsupials of well-known living species are represented by fossil remains in cave-deposits and on "sand-blows" in most of the australian states. the genera thus represented in the pleistocene deposits of australia are _bettongia_ (prehensile rat-kangaroo); _dasyurus_ (native cat); _hypsiprymnus_ (rat-kangaroo); _macropus_ (kangaroo); _perameles_ (bandicoot); _petaurus_ (flying phalanger); _phalanger_ (cuscus); _phascolomys_ (wombat); _sarcophilus_ (tasmanian devil); _thylacinus_ (tasmanian wolf). =cetacea.--= the order cetacea includes whales, dolphins and porpoises. the earliest known forms belong to the sub-order archaeoceti, and whilst absent from australian deposits, are found in the eocene of europe, northern africa and north america. =odontoceti: toothed whales.--= remains of cetacea are first met with in australian rocks in the oligocene (balcombian) of victoria. at muddy creek near hamilton fragments of ribs and other bones of cetacea, not yet determined, occur in the tenacious blue clays of the lower part of the clifton bank section. in australia and new zealand the oldest determinable remains of this order belong to the odontoceti, members of which range from miocene to pliocene. teeth of the toothed whales like _squalodon_ of the miocene of france and bavaria have been found in new zealand (_kekenodon_); in south australia (_metasqualodon_); and in victoria (_parasqualodon_). in victoria the teeth of squalodontidae occur in the janjukian beds of cape otway, waurn ponds and torquay, represented by molars and anterior teeth of _parasqualodon wilkinsoni_ (fig. b, c). the same species also occurs at table cape, tasmania, in beds of similar age. teeth of _metasqualodon harwoodi_ (fig. d) occasionally occur in the white polyzoal rock of the mount gambier district, south australia. the gigantic toothed whale, _kekenodon onamata_ (fig. e) occurs in the marawhenua greensands (oamaru series) at waitaki valley, waihao, ngapara, waikouaiti and milburn in new zealand. the molar teeth of this striking species, with their serrated crowns, measure nearly five inches in length. =ear-bones of whales.--= the tympanic bones of whales are not uncommon in the janjukian beds of waurn ponds, near geelong, victoria; and they are occasionally found in the basement bed of the kalimnan at beaumaris, port phillip. in the absence of any distinctive generic characters they have been referred to the quasi-genus _cetotolithes_ (fig. f). mccoy has expressed the opinion that they may perhaps be referable to the ziphioid or beaked whales, for undoubted remains of that group, as teeth of _ziphius geelongensis_, occur in these same beds; as well as portions of their rostrate crania, in the kalimnan basement beds at grange burn, near hamilton. the large curved and flattened teeth of _ziphius (dolichodon) geelongensis_ are occasionally found, more or less fragmentary, in the polyzoal rock of waurn ponds. [illustration: =fig. .--tooth of scaldicetus macgeei, chapm.= an extinct sperm whale. from the kalimnan beds of beaumaris, port phillip, victoria. about / nat. size.] =kalimnan-scaldicetus.--= from the kalimnan series (lower pliocene) of beaumaris, port phillip, there was described a short time since, a remarkably well preserved specimen of _scaldicetus_ tooth belonging to a new form, _s. macgeei_ (fig. ). another species of the genus, with teeth of a slender form, has been found in the same geological series, at grange burn, near hamilton. in only one other locality besides australia does the genus occur, viz., at antwerp, belgium, in crag deposits of lower pliocene age. =sirenia.--= the order sirenia (manatees and dugongs) is represented in the australian pleistocene by _chronozoön australe_. the remains consist of the parietal and upper part of the occipital bones of the skull, and were discovered in the fluviatile deposits on the darling downs, queensland. this fossil skull, according to de vis, had a shallower temporal fossa and feebler masticating muscles, as well as a less highly developed brain than the existing dugong. =carnivora.--= the order carnivora is represented in australia by the native dog or dingo (_canis dingo_). it is by no means a settled question whether the dingo can boast of very great antiquity. the evidence of its remains having been found under volcanic tuff beds in victoria is not very convincing, for the original record does not indicate the precise position where the bones were found. the fact of the remains of the dingo having been found in cave deposits often associated with extinct marsupials, goes a good way to prove its antiquity. mccoy was strongly inclined to the view of its pleistocene age, and points out that it shows cranial characters intermediate between the dogs of south america and the old world. fossil remains of the dingo, associated with pleistocene mammalian forms have been recorded from the wellington, valley caves, new south wales; from the mount macedon cave, near gisborne; and in the neighbourhood of warrnambool, western victoria. =pinnipedia.--= of the fin-footed carnivores or seals and walruses, the earliest australasian record is that of the remains of a small seal in the okehu shell-beds near wanganui, found in association with the bones of a small moa-bird (_dinornis_). =newer pliocene seal.--= this seal was referred by hector to _arctocephalus cinereus_, a species synonymous, however, with the widely distributed living seal, _otaria forsteri_, lesson, of the southern ocean. another and larger species of eared seal allied to the living fur seal, _otaria forsteri_, occurs in victoria. =pleistocene seal.--= this fossil was named _arctocephalus williamsi_ by mccoy, and was found in pleistocene deposits at queenscliff, port phillip, at feet below the surface, in marl and sand stone overlain with limestone. although referred at the time of description to the pliocene, it has since been proved that at this locality there is a considerable thickness of practically sub-recent material which is more accurately classed with the pleistocene. similar remains of eared seals are not uncommon in the pleistocene deposits of the otway coast. =subrecent human remains.= on turning to the occurrence of "human fossils" in australia we find the geological evidence for any great antiquity of man on this continent to be very scanty and inconclusive. this does not, however, imply that man's existence in australia will not eventually be proved to date back far beyond the period of the "kitchen middens" of modern aspect, such as are now exposed on the slopes behind the sea-beaches, and on the inland camping grounds. almost all the records of australian human remains that have been found in other than ordinary burial places, have proved to be of comparatively recent date. for example, the partially lime-encrusted body found in the cave in the mosquito plains, north of penola, south australia, recorded by tenison woods, is that of an aborigine who, in the early days of settlement, crawled into the cave in a wounded condition. other occurrences of human remains in caves, but of fairly recent date are, a child's skull found in a small cave at bungonia, co. argyle, new south wales, recorded by etheridge; and the non-petrified limb-bones found in a cave at wellington, new south wales, recorded by krefft, which were probably washed in from the surface in recent times. as regards the former, in western australia, as observed by froggatt, the natives at the present time seek shelter in caves, where these occur, instead of building mia-mias. a more interesting, because probably much older, occurrence of human remains has been described by etheridge and trickett from one of the jenolan caves (skeleton cave); and those authors conclude from "the great lapse of time that must have accrued to enable the changes already outlined to have taken place since the introduction of the remains into the skeleton cave," that these remains are ancient. [illustration: =fig. --impressions of footprints in dune sand-rock.= warrnambool, victoria. / nat. size. (_f. c. photo_). (_warrnambool museum_). ] curious footprints supposed to resemble impressions of human feet with accompanying impress as if made by natives seated, have been long known from the older sand-dune rock of warrnambool. they were found at kellas' quarry, on the port fairy road in and at a depth of feet. in november, , a further discovery of similar footprints were found at messrs. steere bros.' quarry, warrnambool, at a depth of feet, as a block of stone was being removed for building purposes. these footprints are even more obscure than those previously found, and it would be unsafe to affirm their human origin, although they are suggestive of such. their antiquity is certainly great, since the lavas and tuffs of the tower hill district are found overlying this old dune-rock. other footprints associated with these resemble those of the dingo and a gigantic bird, possibly like _genyornis_. =probable origin of aborigines.--= ethnology appears to throw more light upon the subject than does geology. australia has in the past been peopled by two distinct types of man. ( ), the ancestors of the tasmanians, now alas, extinct, who according to some authorities came by way of australia from papua through the malay peninsula, passing over to tasmania from the mainland before the separation caused by the subsidence of the bass strait area; and who were represented by a negroid or woolly-haired type: ( ), the present aboriginals of australia, showing affinities with the dravidians of southern india, a primitive race from whose original stock the white caucasian races of europe were derived. by intermarriage with a negroid race like the melanesian, it is supposed that the black caucasian gave rise to the present australian mixed aboriginal type, with negroid features, but possessing the long black hair and keener intellect of the "melanochroi," as the dark eurasian stock was termed by huxley. =aboriginal implements.--= the stone implements fashioned by the tasmanian aboriginals were roughly chipped and of primitive type, of such forms as used at the present day by the bushmen of south africa, and representing the eoliths and palaeoliths of early man in the south of england. the implements of the australian aboriginals on the other hand include besides these both flakes and worked and polished tools, such as were produced by the neolithic men of europe, as contrasted with the typically rough palaeolithic tools of the tasmanian, who never grooved his axes for hafting as did the australian aboriginal. according to some authorities the tasmanians represent palaeolithic or even eolithic man in the character of their implements; whilst the australian resembles the middle or mousterian stage of early man in certain of their ethnological characters and in the forms of their implements, although a marked exception is seen in their manufacture of polished adzes, of the neolithic period and in the use of bone implements such as were used in europe in upper palaeolithic times. so far no human remains or handiwork in the form of chipped implements have been found in other than superficial deposits, either in tasmania or australia. the incised bone-fragment found near ballarat, in a bed of silt beneath a sheet of basalt which flowed from mount buninyong, is believed by some to be evidence of man's handiwork in the early pleistocene, though by others thought to have been cut by the teeth of the "marsupial lion" (_thylacoleo_). a stone axe of basalt, grooved for the purpose of mounting in a handle, was found in gravel at ballarat at a depth of inches from the surface. this, however, is no proof of man's antiquity, for superficial deposits of much greater depth are easily accumulated within a short period. another implement was found at maryborough in queensland in gravels at a depth of feet from the surface, but not below the basalt of the main lead. in this case it is believed that the implement may have fallen into a natural hollow or wombat-burrow. a bone pointer, such as used by native medicine men, was some years ago found buried in the miocene marls of waurn ponds near geelong. its presence in so old a rock is easily explained from the fact that in the aboriginal ceremonies the pointer was buried after the incantations. seeing the difficulties in the way of discovering reliable occurrences of man's handiwork in isolated examples amongst the older superficial deposits of silt and gravels, the ancient sand-dunes of victoria, which date back at least to upper pliocene, should afford favourable conditions for the preservation of any really ancient kitchen middens, did such exist. moreover, these deposits would have been less liable to disturbance when once they were covered, than the inland deposits, for the former are now consolidated into a tolerably hard stone. =antiquity of man in australia.--= a strong argument in favour of a considerable antiquity for man in australia is the fact that the dialects are many, and marriage and tribal customs more complex and intricate than would be found in a comparatively recent primitive race. in any case, it is quite possible, if not probable, that man was in southern australia before the termination of the last phase of volcanic activity, since the tuff beds of koroit, for example, are quite modern and were laid down on a modern sea-beach strewn with shells identical in species and condition with those now found thrown up in the vicinity at high tide. this view is quite compatible with the occurrence of dingo remains (assuming this animal was introduced by man) in cave deposits in australia, associated with extinct forms of marsupials. * * * * * common or characteristic fossils of the foregoing chapter. fishes. _thyestes magnificus_, chapman. silurian: victoria. _asterolepis australis_, mccoy. middle devonian: victoria. _ganorhynchus süssmilchi_, etheridge fil. devonian: new south wales. _gyracanthides murrayi_, a. s. woodward. lower carboniferous: victoria. _acanthodes australis_, a. s. woodward. lower carboniferous: victoria. _ctenodus breviceps_, a. s. woodward. lower carboniferous: victoria. _strepsodus decipiens_, a. s. woodward. lower carboniferous: victoria. _elonichthys sweeti_, a. s. woodward. lower carboniferous: victoria. _physonemus micracanthus_, chapman. lower carboniferous: victoria. _(?) deltodus australis_, eth. fil. carbopermian: queensland. _tomodus (?) convexus_, agassiz. carbopermian: new south wales. _edestus davisii_, h. woodward. carbopermian: w. australia. _peocilodus jonesi_, agassiz. carbopermian: w. australia. _gosfordia truncata_, a. s. woodw. triassic: new south wales. _myriolepis clarkei_, egerton. triassic: new south wales. _apateolepis australis_, a. s. woodw. triassic: new south wales. _dictyopyge robusta_, a. s. woodw. triassic: new south wales. _belonorhynchus gigas_, a. s. woodw. triassic: new south wales. _semionotus australis_, a. s. woodw. triassic: new south wales. _pristisomus latus_, a. s. woodw. triassic: new south wales. _cleithrolepis granulatus_, egerton. triassic: new south wales. _pholidophorus gregarius_, a. s. woodw. triassic: new south wales. _pleuracanthus parvidens_, a. s. woodw. upper trias: new south wales. _sagenodus laticeps_, a. s. woodw. upper trias: new south wales. _palaeoniscus crassus_, a. s. woodw. upper trias: new south wales. _elonichthys armatus_, a. s. woodw. upper trias: new south wales. _elpisopholis dunstani_, a. s. woodw. upper trias: new south wales. _pholidophorus australis_, a. s. woodw. upper trias: new south wales. _psilichthys selwyni_, hall. jurassic: victoria. _leptolepis crassicauda_, hall. jurassic: victoria. _ceratodus avus_, a. s. woodw. jurassic: victoria. _coccolepis australis_, a. s. woodw. jurassic: new south wales. _aphnelepis australis_, a. s. woodw. jurassic: new south wales. _aetheolepis mirabilis_, a. s. woodw. jurassic: new south wales. _archaeomaene tenuis_, a. s. woodw. jurassic: new south wales. _leptolepis talbragarensis_, a. s. woodw. jurassic: new south wales. _lamna daviesii_, eth. fil. lower cretaceous: queensland. _lamna appendiculatus_, agassiz. lower cretaceous: queensland. _corax australis_, chapm. lower cretaceous: queensland. _aspidorhynchus_ sp. lower cretaceous: queensland. _belonostomus sweeti_, eth. fil. and a. s. woodw. lower cretaceous: queensland. _portheus australis_, a. s. woodw. lower cretaceous: queensland. _cladocyclus sweeti_, a. s. woodw. lower cretaceous: queensland. _notidanus marginalis_, davis. cretaceous: new zealand. _lamna compressa_, agassiz. cretaceous: new zealand. _callorhynchus hectori_, newton. cretaceous: new zealand. _ischyodus thurmanni_, pictet and campiche. cretaceous: new zealand. _odontaspis contortidens_, agassiz. cainozoic (bal. and janj.): victoria. _lamna apiculata_, ag. sp. cainozoic (bal. and janj.): victoria. also cainozoic (oamaru series): new zealand. _carcharodon megalodon_, agassiz. cainozoic (bal. janj. and kal.): victoria. also cainozoic (oamaru series): new zealand. _cestracion cainozoicus_, chapm. and pritch. cainozoic (janj. and kal.): victoria. _asteracanthus eocaenicus_, tate sp. cainozoic (janj. and kal.): victoria. _galeocerdo davisi_, chapm. and pritch. cainozoic (janj.): victoria. also cretaceous (waipara series) and cainozoic (oamaru series): new zealand. _carcharoides totuserratus_, ameghino. cainozoic (janj.): victoria. _odontaspis incurva_, davis sp. cainozoic (janj. and kal.): victoria. also cainozoic (oamaru series): new zealand. _oxyrhina retroflexa_, agassiz. cainozoic (janj.): victoria. also cainozoic (oamaru series): new zealand. _carcharodon auriculatus_, blainville sp. cainozoic (janj. and kal.): victoria. _acanthias geelongensis_, chapm. and pritch. cainozoic (janj.): victoria. _ischyodus mortoni_, chapm. and pritch. cainozoic (janj.): tasmania. _notidanus jenningsi_, chapm. and pritch. cainozoic (kal.): victoria. _galeocerdo aduncus_, agassiz. cainozoic (kal.): victoria. _oxyrhina hastalis_, agassiz. cainozoic (rare in balc. and janj., abundant in kal.): victoria. _myliobatis moorabbinensis_, chapm. and pritch. cainozoic (kal.): victoria. _edaphodon sweeti_, chapm. and pritch. cainozoic (kal.): victoria. _labrodon confertidens_, chap. and pritch. cainozoic (kal.): victoria. _diodon formosus_, chapm. and pritch. cainozoic (kal.): victoria. _notidanus marginalis_, davis. cretaceous (waipara series); and cainozoic (oamaru series): new zealand. _myliobatis plicatilis_, davis. cainozoic (oamaru series): new zealand. _sargus laticonus_, davis. cainozoic (oamaru series): new zealand. _ctenolates avus_, a. s. woodw. pleistocene: new south wales. _neoceratodus forsteri_, krefft, sp. pleistocene: new south wales. amphibia. _bothriceps australis_, huxley. carbopermian: new south wales. _bothriceps major_, a. s. woodw. carbopermian: new south wales. _platyceps wilkinsoni_, stephens. triassic: new south wales. reptilia. _ichthyosaurus hectori_, ch. (nom. mut.). triassic: new zealand. _(?) megalosaurus_ sp. jurassic: victoria. _notochelone costata_, owen sp. lower cretaceous: queensland. _ichthyosaurus australis_, mccoy. lower cretaceous: queensland. _ichthyosaurus marathonensis_, eth. fil. lower cretaceous: queensland. _cimoliosaurus leucoscopelus_, eth. fil. upper cretaceous: new south wales. _plesiosaurus australis_, owen. cretaceous: new zealand. _polycotylus tenuis_, hector. cretaceous: new zealand. _cimoliosaurus haastii_, hector sp. cretaceous: new zealand. _tylosaurus haumuriensis_, hector sp. cretaceous: new zealand. _taniwhasaurus oweni_, hector. cretaceous: new zealand. _pallymnarchus pollens_, de vis. pleistocene: queensland and victoria. _crocodilus porosus_, schneider. pleistocene: queensland and victoria. _miolania oweni_, a. s. woodw. pliocene (deep-leads): new south wales. pleistocene: queensland. _miolania platyceps_, owen. pleistocene: lord howe island. _megalania prisca_, owen. pleistocene: queensland. birds. _palaeeudyptes antarcticus_, huxley. cainozoic (oamaru series): new zealand. _dinornis_ sp. cainozoic (petane series): new zealand. _pelecanus proavis_, de vis. pleistocene: queensland. _platalea subtenuis_, de vis. pleistocene: queensland. _anas elapsa_, de vis. pleistocene: queensland. _gallinula strenuipes_, de vis. pleistocene: queensland. _fulica prior_, de vis. pleistocene: queensland. _dromornis australis_, owen. pleistocene: queensland and new south wales. _dromaeus patricius_, de vis. pleistocene. queensland. _dromaeus minor_, spencer. pleistocene: king island. _genyornis newtoni_, stirling and zietz. pleistocene: s. australia. _cnemiornis calcitrans_, owen. pleistocene: new zealand. _harpagornis moorei_, von haast. pleistocene: new zealand. _aptornis otidiformis_, owen sp. pleistocene: new zealand. _dinornis giganteus_, owen. pleistocene and holocene: n. id., new zealand. _pachyornis elephantopus_, owen sp. pleistocene and holocene: s. id., new zealand. _anomalopteryx antiqua_, hutton. pleistocene: s. id., new zealand. mammalia. _ornithorhynchus maximus_, dun. cainozoic (kalimnan or l. pliocene): new south wales. _echidna (proechidna) robusta_, dun. cainozoic (kalimnan): new south wales. _ornithorhynchus agilis_, de vis. pleistocene: new south wales. _echidna (proechidna) oweni_, krefft. pleistocene: new south wales. _wynyardia bassiana_, spencer. cainozoic (kalimnan): tasmania. _dasyurus maculatus_, kerr sp. pleistocene: victoria and new south wales. living: queensland, new south wales, victoria and tasmania. _phascolomys pliocenus_, mccoy. cainozoic (werrikooian): victoria. _sarcophilus ursinus_, harris sp. pleistocene: victoria and new south wales. living: tasmania. _thylacinus cynocephalus_, harris sp. pleistocene: victoria and new south wales. living: tasmania. _thylacinus spelaeus_, owen. pleistocene: queensland and new south wales. _thylacinus major_, owen. pleistocene: queensland. _peragale lagotis_, reid sp. pleistocene: new south wales. living: s. australia and w. australia. _perameles gunni_, gray. pleistocene: victoria. living: queensland and victoria. _phascolomys parvus_, owen. pleistocene: queensland. _phascolonus gigas_, owen. pleistocene: queensland, new south wales and s. australia. _macropus titan_, owen. pleistocene: queensland, victoria, new south wales and s. australia. _macropus anak_, owen. pleistocene: queensland, s. australia and new south wales. _procoptodon goliah_, owen sp. pleistocene: queensland, new south wales and victoria. _sthenurus atlas_, owen sp. pleistocene: queensland, new south wales, victoria, and south australia. _sthenurus occidentalis_, glauert. pleistocene: w. australia. _palorchestes azael_, owen. pleistocene: queensland, new south wales and victoria. _diprotodon australis_, owen. pleistocene: queensland, new south wales, victoria and s. australia. _nototherium mitchelli_, owen. pleistocene: queensland, s. australia and victoria. _thylacoleo carnifex_, owen. pleistocene: queensland, new south wales, victoria and w. australia. _parasqualodon wilkinsoni_, mccoy sp. cainozoic (janjukian): victoria and tasmania. _metasqualodon harwoodi_, sanger sp. cainozoic (janjukian): s. australia. _kekenodon onamata_, hector. cainozoic (oamaru series): new zealand. _cetotolithes nelsoni_, mccoy. cainozoic (janjukian): victoria. _ziphius (dolichodon) geelongensis_, mccoy. cainozoic (janjukian): victoria. _scaldicetus macgeei_, chapm. cainozoic (kalimnan): victoria. _chronozoön australis_, de vis. pleistocene: queensland. _canis dingo_, blumenbach. late pleistocene or holocene: victoria. _otaria forsteri_, lesson. pliocene (petane series): n. id., new zealand. _arctocephalus williamsi_, mccoy. pleistocene: victoria. * * * * * literature. fishes. silurian.--chapman, f. proc. r. soc. vict., vol. xviii. (n.s.), pt. ii. , pp. - , pls. vii. and viii. (_thyestes_). devonian.--mccoy, f. prod. pal. vict., dec. iv. , pp. , , pl. xxxv. figs. , _a_, _b_ (_asterolepis_). etheridge, r. jnr. rec. austr. mus., vol. vi. pp. - , pl. xxviii. (_ganorhynchus_). carboniferous and carbopermian.--woodward, h. geol. mag., dec. iii. vol. iii. , pp. - , pl. i. (_edestus_). etheridge, r. jnr. geol. and pal. queensland, , p. , pl. xxxix. fig. (_deltodus_). de koninck, l. g. mem. geol. surv. new south wales, pal. no. , , p. , pl. xxiv., fig. (_tomodus_). woodward, a. s. mem. nat. mus. melbourne, no. . (mansfield series). triassic.--johnston, r. m. and morton, a. proc. r. soc. tasmania ( ), , pp. - ; ibid. ( ), , pp. - (_acrolepis_). woodward, a. s. mem. geol. surv. new south wales, pal. no. , (gosford). ibid. no. , (st. peters). jurassic.--woodward, a. s. mem. geol. surv. new south wales, pal. no. , . id., ann. mag. nat. hist., ser. vii. vol. xviii. , pp. - , pl. i. (_ceratodus_). hall, t. s. proc. r. soc. vict. vol. xii. (n.s.) pt. ii. , pp. - , pl. xiv. chapman, f. rec. geol. surv. vict. vol. iii. pt. , , pp. - , pl. xxxix. (_ceratodus_). cretaceous.--etheridge, r. jnr. proc. linn. soc. new south wales, vol. iii. ser. , , pp. - , pl. iv. idem, geol. and pal. queensland, , pp. - . davis, j. w. trans. r. dubl. soc. vol. iv. ser. . , pp. - , pls. i.-vii. (cretaceous and cainozoic of new zealand). etheridge, r. jnr. and woodward, a. s. trans. r. soc. vict., vol. ii. pt. ii. , pp. - , pl. i. (_belonostomus_). woodward, a. s. ann. mag. nat. hist., ser. , vol. xix. , pp. - , pl. x. (_portheus_ and _cladocyclus_). chapman, f. proc. r. soc. vict., vol. xxi. (n.s.), pt. ii. , pp. , (_corax_). cainozoic.--mccoy, f. prod. pal. vict., dec. ii. , pp. - , pl. xi. (_carcharodon_). chapman, f. and pritchard, g. b. proc. r. soc. vict., vol. xvii. (n.s.), pt. i. , pp. - , pls. v.-viii. idem, ibid, vol. xx. (n.s.), pt. i. , pp. - , pls. v.-viii. see also davis, j. w. (_cretaceous_). pleistocene.--etheridge, r. jnr. geol. and pal. queensland, , p. (_neoceratodus_). woodward, a. s. rec. geol. surv. new south wales, vol. vii. pt. , , pp. - , pl. xxiv. (_ctenolates_). amphibia. huxley, t. h. quart. journ. geol. soc., vol. xv. , pp. - , pl. xxii. figs. , (_bothriceps_). stephens, w. j. proc. linn. soc. new south wales, ser. . vol. i. , pp. - . ibid., , pp. - , pl. xxii. ibid., vol. ii. , pp. - . woodward, a. s. rec. geol. surv. new south wales, vol. viii. pt. , , pp. - , pl. li. (_bothriceps_). reptilia. jurassic and cretaceous.--hector, j. trans. n.z. inst., vol. vi. , pp. - . cretaceous.--mccoy, f. proc. r. soc. vic., vol. viii. pt. i. , p. (_plesiosaurus_). ibid., vol. ix. pt. ii. , p. (_ichthyosaurus_). owen, r. geol. mag., dec. i. vol. vii. , pp. - , pl. iii. (_plesiosaurus_). id., quart. journ. geol. soc. vol. xxxviii. , pp. - (_"notochelys" = notochelone_). etheridge, r. jnr. proc. linn. soc. new south wales, ser. , vol. iii. , pp. - , pls. vii. and viii. (_ichthyosaurus_). id., geol. and pal. queensland, , pp. - . hutton, f. w. trans. n.z. inst. vol. xxvi. , pp. - , pl. (_cimoliosaurus_). pleistocene.--etheridge, r. jnr. rec. geol. surv. new south wales, vol. i. pt. , , pp. - (_miolania_). id., geol. and pal. queensland, , pp. - . aves. miocene.--huxley, t. h. quart. journ. geol. soc. vol. xv. , pp. - . also hector, j. trans. n.z. inst. vol. iv. , pp. - , pl. (_palaeeudyptes_). chapman, f. proc. r. soc. vict. (n.s.) pt. i. , pp. - , pls. iv. and v. pleistocene and holocene.--von haast, j. trans. n.z. inst., vol. iv., , pp. - ; and vol. vi. , pp. - (_harpagornis_). owen, r. memoirs on the extinct wingless birds of new zealand, london, , vols. de vis, c. w. proc. r. soc. queensland, vol. vi. pt. i. , pp. - . id., proc. linn. soc. new south wales, vol. iii. ser. , , pp. - , pls. xxxiii.-xxxvi. (carinatae). etheridge, r. jnr. rec. geol. surv. new south wales, vol. i. pt. , , pp. - , pls. xi.-xiii. (_dromornis_). id., geol. and pal. queensland, , pp. - . hutton, f. w. trans. n.z. inst., vol. xxiv. , pp. - (moas). id., ibid., vol. xxv. , pp. - , pl. (_anomalopteryx_). id., ibid., vol. xxix. , pp. - , figs. (moas). id., ibid., vol. xxxviii. , pp. and (_emeus crassus_). hamilton, a. ibid, vol. xxvi. , pp. - (bibliography of moas). ibid, vol. xxx. , pp. and (_euryapteryx_). stirling, e. c. and zietz, a. h. c. mem. r. soc. s. austr., vol. i. pt. ii. , pp. - , pls. xix.-xxiv. (_genyornis_). spencer, w. b. vict. nat. vol. xxiii. , pp. and ; also spencer, w. b. and kershaw, j. a. mem. nat. mus. melbourne no. , , pp. - , pls. i.-vii. (_dromaeus minor_). mammals. huxley, t. h. quart. journ. geol. soc., vol. xv. , pp. - (_phocaenopsis_). mccoy, f. prod. pal. vict., dec. i. , pp. , , pls. iii.-v. (_phascolomys_). ibid, dec. ii. , pp. - , pl. xi. and dec. vi. , pp. and , pl. lv. (_squalodon_). ibid, dec. iii. , pp. - , pl. xxi. (_thylacoleo_). ibid, dec. iv. , pp. - , pl. xxxi.-xxxiii. (_diprotodon_). ibid, dec. v. , pp. - , pl. xli. and xlii. (_arctocephalus_). ibid, dec. vi. , pp. - , pl. li. (_macropus_): pp. - , pl. li.-liii. (_procoptodon_): pp. - , pl. liv. (_cetotolithes_); pp. and , pl. lv. (_physetodon_). ibid, dec. vii. , pp. - , pl. lx. (_canis dingo_): pp. - , pl. lxxii. and lxii. (_sarcophilus_): pp. - , pl. lix. (_ziphius_). owen, r. extinct mammals of australia, london , vols. hector, j. trans. n.z. inst., vol. xiii. , pp. - , pl. (_kekenodon_). lydekker, r. cat. foss. mammalia, brit. mus. part v. . id., handbook to the marsupialia, and monotremata. allen's nat. library, , pt. iii. pp. - . de vis, c. w. proc. linn. soc. new south wales, vol. viii. pt. , , p. (sirenian). id., ibid, vol. x. , pp. - , pls. xiv.-xviii. (macropodidae). id., proc. r. soc. vict., vol. xii. (n.s.), pt. i, , pp. - (marsupials). etheridge, r. jnr. geol. and pal. queensland, , pp. - (pleistocene mammals). dun, w. s. rec. geol. surv. new south wales, vol. iii. pt. , , pp. - , pl. xvi. (_palorchestes_). ibid., vol. iv. pt. , , pp. - , pls. xi. and xii. (monotremes). stirling, e. c. and zietz, a. h. c. mem. roy. soc. s. australia, vol. i. pt. i. (descr. of _diprotodon_, manus and pes.). spencer, w. b. proc. zool. soc. , pp. - , pls. xlix. and l. (_wynyardia_). hall, t. s. proc. r. soc. vict. vol. xxiii. (n.s.), pt. ii. , pp. - , pl. xxxvi. (rev. of squalodontidae). spencer, w. b. and walcott, r. h. proc. r. soc. vict., vol. xxiv. (n.s.), pt. i. , pp. - , pls. xxxvi.-xxix. (_thylacoleo_). chapman, f. rec. geol. surv. vict., vol. iii. pt. , , pp. - , pl. xl. (_scaldicetus_). woods, j. e. t. geol. observations in s. australia, , pp. and (human remains): also krefft, g. australian vertebrata, recent and fossil, , p. ; etheridge, r. jnr. rec. geol. surv. new south wales, vol. iii. pt. , , pp. - ; etheridge, r. jnr. and trickett, o. ibid., vol. vii. pt. , , pp. - . appendix.--on the collection and preservation of fossils. the tools and other paraphernalia necessary for fossil collecting are fortunately within the reach of all. the principal of these is a geological hammer, preferably with a pick at one end of the head and the opposite end square-faced. the pick end is useful for digging out fossils from soft clays, or for extracting a block of fossils entire. the square end is employed for breaking up the slabs or masses containing fossils. to get good results, much will of course depend upon one's skill in striking the right face of a block. if bedding planes are present on the lump from which we wish to extract our fossils, it will be well to strike at right angles to these layers in order to split them asunder, thus exposing a shell-layer corresponding to the original surface of the ancient sea-bed upon which the organisms accumulated. in some cases the splitting of fossiliferous rocks may be best carried out with the pick end, provided it be not too sharply curved. the hammer should be faced with steel, for many fossiliferous rocks, especially compact limestones, are apt to severely try the temper of an ill-made tool. a chisel, of chilled steel, should accompany the hammer, since this is often of the greatest use in working out large fossils, more particularly those that are buried in a cliff or quarry face. the process of extracting difficult specimens should never be hurried, for one often gets surprisingly good results with a little extra care. a strong pocket knife may be used in trimming specimens and partially cleaning shells that can be safely manipulated on the spot, but the final cleaning should be left until the return home. the knife is also useful for cleaning slates and shales, since the chisel-edge is frequently a trifle too thick for this kind of work. for the more delicate fossils, means for careful packing should be provided; chip-boxes and cotton-wool being indispensable for the smaller specimens. a ready method of packing the fossils obtained from the friable, sandy tertiary deposits is to store them in tins, the contents of which can be firmly secured from rattling by filling up with sand. this sand, however, should be taken from the same bed in which the fossils occur, so as to get no admixture of the smaller shells from another formation or deposit; for although we may not wish to examine the finer material ourselves, it will yield in many cases a rich harvest to our microscopical friends, such residues containing microzoa, as shells of foraminifera, polyzoa and carapaces of the ostracoda. the residues referred to may be obtained from many of our marls and rubbly limestones by the simple process of washing in water, and repeatedly pouring off the finest clayey mud, until only a sandy deposit remains, which can then be dried and sorted over by the aid of a lens or low power microscope. =hints on fossil collecting.--= as regards the places most suitable for collecting fossils, the cainozoic beds are perhaps, the most accessible to a beginner, especially in victoria. for instance, the cliff exposures at beaumaris, port phillip, will afford a plentiful supply of the little heart-shaped sea-urchin, _lovenia_, and an occasional _trigonia_ and _limopsis_, as well as many other fossils of the great group of the shell-fish or mollusca. the richest bed containing the sharks' teeth at the above locality is almost perpetually covered with a bed of shingle, but can be reached by digging at the cliff-base. isolated specimens, however, although rather the worse for wear, may often be picked up amongst the shingle, having been washed up from the foreshore by the tide. an enticing band of large bivalve shells (_dosinea_), can be seen halfway up the cliffs, near the baths at this locality, but are somewhat disappointing, for when obtained they crumble to pieces in the hand, since their shells are composed of the changeable form of carbonate of lime called aragonite, which has decomposed in place in the bed, after the shells were covered up by the deposit. good collections of shells of the balcombian series may be easily made at balcombe's bay and grice's creek, port phillip. they can there be dug out of the grey-blue clay with a knife, and afterwards cleaned at leisure by means of a soft tooth brush dipped in water. in the cement stone at the same place there are numerous shells of pteropods or "sea-butterflies" (_vaginella_), and specimens of the stone may be obtained, showing myriads of the porcelain-like shells, and also their internal casts in the hard greenish coloured matrix. the ferruginous or ironstone beds seen in the flemington railway cutting, melbourne, is an old marine shell-bank, resting on basalt. the shells have all been dissolved away, and only their casts and moulds remain. these impressions are, however, so faithfully moulded that the ornamentation of each shell can often be reproduced on a squeeze taken with a piece of modelling wax or plasticine. such fossil remains are easily collected by carefully breaking up the blocks of ironstone with a hammer. quarries in the older limestones and mudstones in victoria, new south wales and other states, are often good hunting grounds for fossils. the quarry at cave hill, lilydale, for example, will be found very profitable, for the limestone is full of corals and molluscan shells; whilst the friable or rubbly portion is worth breaking down for the smaller fossils. the bed-rock (silurian) of melbourne is in places very fossiliferous; the sandstones of moonee ponds creek generally affording a fair number of brachiopods, and occasionally corals. the mudstones of south yarra, studley park, yan yean, and other places on the same geological horizon, contain a rich fauna, to be obtained only by the assiduous collector who will search over and break up a large number of blocks. practice in this work makes a good collector; although of course one must know something about the objects looked for, since many apparently obscure fossil remains of great interest might easily be passed over for lack of knowledge as to what should be expected to occur at each particular locality. many other good collecting grounds might here be alluded to, but we have purposely cited only a few near melbourne, since a selection from other parts of australasia may easily be made from the localities mentioned in connection with the various groups of fossils dealt with in the systematic portion of this work. =preservation of fossils.--= many of the cainozoic fossils from the shelly sands and clays are extremely delicate, owing in some cases to their being imperfectly preserved, seeing that they frequently contain in their shell-structure layers of the unstable form of carbonate of lime called aragonite. fossils containing aragonite are:--calcareous sponges; corals; bivalved shells, except oysters, pectens, and the outer layer of _spondylus_, _pinna_, and _mytilus_; gasteropods (with a few exceptions); and cephalopods. in some of these, however, a transformation of the aragonite into calcite enables the fossil to be permanently preserved. the delicate fossils referred to should be dipped in weak glue or gelatine and left to dry; after which their final cleaning can be done with the aid of a little warm water and a soft brush. certain of the clays and mudstones, both of cainozoic and jurassic ages which show remains of plants, such as leaves and fern fronds, are often best treated with a thin surface layer of paper varnish, before they lose the natural moisture of the rock; for when they become perfectly dry the thin carbonaceous film representing the original leaf-substance peels off, and the fossil is consequently destroyed. a method of treatment for cainozoic leaves, by dipping them in warm vaseline and brushing off the superfluous material, has been described by mr. h. deane. =storing fossils for reference.--= fossils specimens are generally best displayed in cardboard trays; or if thin wooden paper-covered tablets are used, say of about - in. thickness and cut to proportionate sizes, the fossils should be held in place by pins for easy removal, unless more than one example can be shown together, exhibiting all aspects, when they can be secured to the tablet by a touch of seccotine. the smaller shells may be displayed in glass topped boxes, which in turn may be stuck down to tablets or placed in trays. index. aboriginal implements, aborigines, probable origin of, _acanthias_, _acanthodes_, _acanthosphaera_, _acanthothyris_, , _acentrophorus_, _acrolepis_, _actaeon_, _actinoceras_, , _actinocrinus_, _actinodesma_, , _actinopteria_, , _actinostroma_, , _adeona_, _aechmina_, _aeschna_, _aetheolepis_, _agathiceras_, agnatha, _agnostus_, _allodesma_, _ambonychia_, _ammodiscus_, , _ammonites_, , , ammonoidea, _amoeba_, , amphibia, structure of, _amphistegina_, _amplexus_, _ampyx_, _amusium_, _anas_, _anchura_, _ancilla_, , , _ancyloceras_, , angiospermeae, characters of, annelida, _anomalina_, _anomalopteryx_, _antedon_, anthozoa, , antiquity of man in australia, _aparchites_, _apateolepis_, _aphnelepis_, _apocynophyllum_, _aptornis_, _aptychopsis_, _arabellites_, _arachnoides_, _araucarioxylon_, _araucarites_, _arca_, , , _archaeocidaris_, _archaeocyathina_, archaeocyathinae, _archaeomaene_, _archaeopteryx_, _arctocephalus_, _arenicolites_, argillaceous rocks, _argilloecia_, _?argiope_, _argonauta_, arthropoda, structure and subdivisions of, , _asaphus_, , _aspidorhynchus_, _astarte_, _asteracanthus_, , asteroidea, _asterolepis_, _astralium_, , _astropecten_, _athyris_, , , _atrypa_, , , _aturia_, _atys_, _aucella_, _aulopora_, australian fossiliferous strata, - . aves, aviculopecten, , _axopora_, bactronella, _baculites_, _baiera_, , _bairdia_, _balanophyllia_, _balanus_, balcombian bivalves, " gasteropods, bandicoot, , _bankivia_, _banksia_, , _barbatia_, , barnacles, _barnea_, _bathytoma_, _bela_, _belemnites_, , , belemnoidea, _bellerophon_, , , , _belonorhynchus_, _belonostomus_, _bettongia_, _beyrichia_, , , _biloela_, _bipora_, birds, fossil, , _biziura_, blastoidea, distribution and characters of, , blue-green algae, , bog iron-ore, _bolodon_, _bombax_, bone-beds, bone-breccias, _bothriceps_, _botryocrinus_, brachiopoda, structure of, , brachiopod limestone, _brachymetopus_, _brachyphyllum_, bracken fern, _brissopsis_, brittle-stars, characters of, , _bronteus_, , _bryograptus_, , , bryophyta, characters of, _buccinum_, _buchozia_, _bulimina_, , _bulinus_, , _bulla_, _bullinella_, , _bythocypris_, _bythotrephis_, cainozoic balanidae, " bird, victoria, " bivalves, " brachiopods, " brittle-stars, " chitons, " corals, " crabs, " echinoids, irregular, " echinoids, regular, " fishes, " foraminifera, " gasteropods, " gasteropods, new zealand, " holothuroidea, " insects, " lepadidae, " ostracoda, " and pleistocene reptiles, " plants, " polyzoa, cainozoic radiolaria, " scaphopods, " sponges, " starfishes, " strata, , calcareous rocks, " sponges, _callograptus_, _callorhynchus_, _calymene_, , , calyptoblastea, _calyptraea_, , , _camarotoechia_, , , cambrian bivalves, " brachiopods, " crinoids, " foraminifera, " gasteropods, " ostracoda, " plants, " radiolaria, " sponges, _cameroceras_, _campanularia_, _campophyllum_, , _cancellaria_, , , _canis_, cannel coal, _capitosaurus_, _capulus_, carbonaceous rocks, carboniferous brachiopods, " crinoids, " fishes, " foraminifera, " gasteropods, " ostracoda, " plants, carbopermian bivalves, " blastoids, " brachiopods, " cephalopods, " corals, " crinoids, " fishes, " foraminifera, " gasteropods, " labyrinthodonts, " ostracoda, " palaeechinoids, " phyllopoda, " plants, " sponges, " starfishes, " trilobites, _carcharodon_, , , _carcharoides_, _cardiola_, , _cardita_, , _cardium_, , , , carnivora, _carposphaera_, _carpospongia_, _caryocaris_, , _cassidulus_, _catenicella_, _cellaria_, _cellepora_, _cenellipsis_, _cenosphaera_, , cephalopoda, characters of, _ceratiocaris_, _ceratodus_, , _ceratotrochus_, _cerithiopsis_, _cerithium_, , _cestracion_, , , cetacea, _cetotolithes_, _chaenomya_, chaetopoda, _chama_, changes of climate in the past, cheilostomata, , _cheirurus_, , _chelodes_, cherts, _chione_, , , _chiridota_, _chironomus_, _chiton_, _chonetes_, , , chordata, _chosornis_, _chronozoön_, _cicada_, _cidaris_, _cimoliosaurus_, _cinnamomum_, _cinulia_, cirripedia, habits and structure of, _cladochonus_, _cladophlebis_, , , cladophora, classification of animals, _clathrodictyon_, _clausilia_, _clavigera_, clays, _cleiothyris_, _cleithrolepis_, , , _climacograptus_, _climatius_, _clonograptus_, , , _clypeaster_, _cnemiornis_, coals, _coccolepis_, _cocconema_, _coccosteus_, coelenterata, characters of, _coleolus_, collecting fossils, _colubraria_, _columbarium_, , , _columbella_, _conchothyra_, _conocardium_, , conodonts, _conosmilia_, _conularia_, , , _conus_, , , , _coprosmaephyllum_, coral limestone, corals, , _corax_, _corbicula_, _corbula_, , , , _cordaites_, _cornulites_, _coscinocyathus_, _coxiella_, _crassatellites_, , _crenella_, _crepicephalus_, _crepidula_, cretaceous (lower and upper) cephalopods, " cephalopods, new zealand, " cheilostomata, " crinoids, " echinoids (irregular), " (lower) fishes, " fishes, new zealand, " foraminifera, " gasteropods, " plants, " radiolaria, " (lower) reptiles, " reptiles, new zealand, " scaphopods, " sponges, crinoidal limestone, crinoidea, occurrence and structure of, , _crioceras_, _crisia_, _cristellaria_, _crocodilus_, _cromus_, crustacea, an archaic group, " development of, " fossil, _cryptodon_, _cryptograptus_, _cryptoplax_, _cryptostomata_, , _ctenodonta_, , _ctenodus_, , _ctenolates_, _ctenostreon_, _cucullaea_, , , _cultellus_, _cuna_, , , _cupressinoxylon_, , _cupressus_, _cuscus_, cuttle-fishes, cyanophyceae, _cyathocrinus_, _cyathophyllum_, , , _cyclas_, _cycloceras_, _cyclolituites_, _cyclometopa_, _cyclonema_, cyclostomata, _cydnus_, _cymbella_, _cyphaspis_, _cyphon_, _cypraea_, , , , , _cypricardinia_, cyprid limestone, _cyrenopsis_, _cyrtoceras_, , _cyrtograptus_, _cyrtina_, , _cyrtolites_, cystideans, _cystiphyllum_, _cythere_, , _cytherella_, _?cytheridea_, _cytheropteron_, _dadoxylon_, _dalmanites_, , , , _daonella_, darter, _?darwinula_, _dasyurus_, , decapoda, deep leads, fruits of, " insects from, _deltodus_, _deltopecten_, _dendrocrinus_, , _dendrocygna_, _dendrograptus_, _dendrophyllia_, _dennantia_, _dentalium_, dentition of reptiles, _deontopora_, _desmoceras_, devonian bivalves, " brachiopods, " cephalopods, " corals, " crinoids, " fishes, " gasteropods, " ostracoda, " plants, " radiolaria, " scaphopods, " stromatoporoids, " trilobites, diadactyla, diatomite, diatoms, _dicellograptus_, , _dichograptus_, _dicranograptus_, , _dictyonema_, and allies, _dictyopyge_, _didymograptus_, , _?didymosorus_, _dielasma_, , _dikellocephalus_, _dimetrodon_, _dimya_, , , _dinesus_, dingo, , _dinornis_, , , , _diodon_, , _dione_, _diphyphyllum_, _diplograptus_, , , , _diprotodon_, , , _diprotodon_-breccias, diprotodontia, _discina_, _discorbina_, _dissocheilus_, _dithyrocaris_, _ditrupa_, _ditrupa_ limestone, _dolichodon_, _dolichometopus_, _dolium_, _donax_, , _dorsetensia_, _dosinea_, , _drillia_, , _dromaeus_, , _dromornis_, duck, _duncaniaster_, ear-bones of whales, early observers, _eburnopsis_, , _echidna_, , _echinocyamus_, echinodermata, characters of, , " divisions of, echinoidea, _echinolampas_, , _echinoneus_, _echinus_, _ecionema_, _edaphodon_, _edestus_, _edmondia_, , , _eglisia_, elephant-fish, , elephant-tusk shells, elevated sea-beds, _elonichthys_, , _elpisopholis_, _emarginula_, emu, _encrinurus_, _endoceras_, _endothyra_, , _entalophora_, _entomis_, _ephemera_, _equisetites_, errant worms, _erycina_, _erymnoceras_, _estheria_, _eucalyptus_, , , _eulima_, _eunema_, _eunicites_, _euomphalus_, , , _eupatagus_, _euphemus_, _eurydesma_, eurypterida, _euthria_, _eutrochus_, evolution of life-forms, _fagus (notofagus)_, falcon, _fasciolaria_, , _favosites_, , , , feather-star, _fenestella_, , _fibularia_, fishes, fossil, " primitive types, " true, fish-lizards, , , , _fissilunula_, , _fissurellidea_, _fistulipora_, , _flabellina_, _flabellum_, , flightless pigeon goose, flints, flying phalanger, foraminifera, characters of, , " fossil, foraminiferal limestone, fossil faunas, differences in, fossiliferous strata, australia, - " strata, new zealand fossil, origin of name, fossils an index to age of strata, , " nature of, " petrifaction of, " preservation of, " structure preserved in, fossil wood, , , _frondicularia_, , fruits of the deep leads, _fulica_, _fusus_, , _galeocerdo_, , _gallinula_, _gangamopteris_, _ganorhynchus_, _gari_, gasteropoda, characters of, _gastrioceras_, _geinitzina_, _genyornis_, , geological epochs, - geology, scope of, giant kangaroo, " lizard, " penguin, _gibbula_, _ginkgo_, , _girvanella_, , , glauconite casts of foraminifera, _glossograptus_, , _glossopteris_, _glycimeris_, , _glyphioceras_, _gomphonema_, gondwana-land, _goniatites_, , _goniograptus_, , _gosfordia_, _gosseletina_, _grammysia_, _granatocrinus_, _graphularia_, , graptolites, bendigo series, " lancefield series, " nature of, , " tasmania, graptolitoidea, _gregoriura_, _griffithides_, _gromia_, ground pigeon, _gryphaea_, _grypotherium_, guide fossils, gymnospermeae, characters of, _gyracanthides_, _gyroceras_, _gyrodoma_, _halimeda_ limestone, _haliotis_, , _haliserites_, _halysites_, _hamites_, _hapalocrinus_, _haploceras_, _haplophragmium_, , _harpa_, , , _harpactocarcinus_, _harpagornis_, _hawk_, _helicocrinus_, _helicotoma_, _heliolites_, , _heliopora_, _heliosphaera_, _helix_, _hemiaster_, _hemipatagus_, _heterocrinus_, heteropoda, _heteropora_, hexactinellid sponge, , hinge-structure, in bivalves, _holaster_, holothuroidea, _homalonotus_, , _hornera_, _huenella_, human remains, sub-recent, _hyalostelia_, , _hybocrinus_, _hydractinia_, , hydrozoa, , _hymenocaris_, _hyperammina_, _hyolithes_, , , _hypothyris_, _hypsiprymnus_, ibis, _ichthyosaurus_, , , _idiostroma_, _idmonea_, _illaenus_, indusial limestone, _inoceramus_, , insects, , ironstone, irregular echinoids, _ischnochiton_, _ischyodus_, , _isochilina_, _isocrinus_, , janjukian bivalves, " gasteropods, _jonesina_, jurassic bird, " bivalves, " brachiopods, " cephalopods, " fishes, " foraminifera, " gasteropods, " insects, " ostracoda, " phyllopoda, " plants, " reptiles, " scaphopods, kalimnan bivalves, " gasteropods, kangaroo, _keeneia_, _kekenodon_, , kerosene shale, _kionoceras_, _kloedenia_, _labrodon_, labyrinthodontia, _lagena_, _?lagria_, _lamna_, , , lamp-shells, , _lasiocladia_, _lasiograptus_, , _latirus_, , _laurus_, _leaia_, leda, , , , , leonardo da vinci, _lepas_, _leperditella_, _leperditia_, , , , , _lepidocyclina_, , " limestone, _lepidodendron_, , , " beds, _lepralia_, , _leptaena_, , _leptoclinum_, , _leptodesma_, _leptodomus_, _leptograptus_, _leptolepis_, , , _lepton_, _lichas_, _lichenopora_, _lieberkuehnia_, _lima_, , , _limatula_, limestones formed by organisms, _limnaea_, _limopsis_, , , _limulus_, _lingula_, , , , _linthia_, , _liopyrga_, _liotia_, , lithistid sponges, , lithological evidence, value of, _lithophaps_, _lithothamnion_, _lituites_, _lituola_, _loganograptus_, _lophophyllum_, _lorica_, _lotorium_, , , _lovenia_, lower cambrian trilobites, " cretaceous bivalves, " " brachiopods, " " cephalopods, " " crab, " " dragon-fly, " " fishes, " " reptiles, " mesozoic fishes, " ordovician graptolites, new zealand, " ordovician graptolites, victoria, _loxoconcha_, _loxonema_, , , , _lucina_, , lung-fish, _lunucammina_, _lunulicardium_, _lunulites_, _lyriopecten_, _maccoyella_, , _macrocephalites_, _macrocheilus_, _macrocypris_, , _macropora_, _macropus_, , _macrotaeniopteris_, _mactra_, , , madrepore limestone, _magasella_, , _magellania_, , , _magnolia_, maiden-hair tree, mail-shells, mammalia, early types, mammals, fossil, manatees and dugongs, _marginella_, , _marginulina_, marsupial lion, marsupial, oldest known australian, marsupials, " pleistocene and living, _martiniopsis_, _mastodonsaurus_, material for fossil collecting, _megalania_, _megalosaurus_, _melania_, _melosira_, _membranipora_, , _meretrix_, , , _mesoblastus_, _mesostigmodera_, mesozoic strata, _metablastus_, _metasqualodon_, , metazoa, _micraster_, _microdiscus_, _mikrogromia_, _millepora_, _milleporids_, _miliolina_, , , miocene bird, new zealand, " leaf-beds, miolania, mitra, , , moa-birds, - , _modiola_, , _modiolaria_, _modiolopsis_, mollusca, characters of, , , molluscoidea, characters of, , , monactinellid sponges, , _monogenerina_, _monograptus_, , _monostychia_, _monotis_, monotremata, _monticulipora_, monticuliporoids, _montlivaltia_, moor-hen, _mopsea_, _morio_, , mound-builders, _mourlonia_, mud-fish, , muds, mudstone, multituberculata, _murchisonia_, , , _murex_, , , _myodora_, , _myriolepis_, , _mytilarca_, _mytilus_, , , , naming of animals, _nassa_, , , _natica_, , , , , native cat, , " dog, " honeysuckle, , nautiloidea, _nautilus_, , , , _navicula_, _nebalia_, _necrastur_, _neoceratodus_, newer pliocene seal, _newtoniella_, new zealand fossiliferous strata, _niso_, , _nodosaria_, , _nonionina_, _normanites_, _notasaphus_, _notidanus_, , , , _notochelone_, , _notophyllia_, _nototherium_, _nubecularia_, , _nucleospira_, _nucula_, , , , , , _nuculites_, , nullipore limestone, _nummulites_, , nummulitic limestone, _nyroca_, octopoda, _octopus_, _odontaspis_, , , odontoceti, _odontopleura_, , _odostomia_, , _oenonites_, _olenellus_, , _oliva_, _ommatocarcinus_, _omphalotrochus_, oolitic ironstone, _ophileta_, , ophiuroidea, _orbiculoidea_, _orbitoides_, ordovician bivalve, " brachiopods, " cephalopods, " corals, " crinoids, " gasteropods, " phyllocarida, " radiolaria, " sponges, " trilobites, _ornithorhynchus_, , _orthis_, , , , " limestone, _orthoceras_, , , , , _orthonota_, _orthothetes_, ostracoda, features of carapace, " habits of, " structure of, _ostrea_, , , _otaria_, _oxyrhina_, , , oxystomata, _oxytelus_, _pachydomus_, _pachyornis_, , _pachypora_, , _palaeaster_, , _palaeeudyptes_, , _palaeohatteria_, _palaeolycus_, _palaeoneilo_, , _palaeoniscus_, , , _palaeopelargus_, palaeozoic chitons, " cladophora, " cryptostomata, " errant worms, " strata, " trepostomata, _palissya_, , _pallymnarchus_, _palorchestes_, _panda_, _panenka_, _paracyainus_, _paracyclas_, , _paradoxechinus_, _paradoxorhyncha_, _parasqualodon_, , _pareiasaurus_, _patella_, , _pecten_, , , , , , , , pelecypoda, characters of, " hinge structure of, pelican, _pelicanus_, _pelosina_, _?peltopleurus_, _pentacrinus_, , _pentagonaster_, _pentamerus_, , _penteune_, _peragale_, _perameles_, , _perisphinctes_, permian and triassic reptiles, _perna_, _peronella_, _persoonia_, _petaurus_, _petraia_, _phacops_, , , phalanger, _phanerotrema_, _phascolomys_, , _phascolonus_, _phialocrinus_, _phillipsia_, _phoenicopsis_, _pholas_, _pholidophorus_, , _phos_, _phragmoceras_, _phryganea_, phylactolaemata, phyllocarida, structure of, _phyllocladus_, _phyllograptus_, , phyllopoda, _phyllotheca_, _physa_, _physonemus_, pigeon, _pinna_, pinnipedia, _pisania_, _?pisocrinus_, _placopsilina_, _placotrochus_, _placunanomia_, , _plagiarca_, _plagiaulax_, _planorbis_, plants, fossil, plant series, characters of, _platalea_, _platyceps_, _platyceras_, , , , _platycoila_, _platycrinus_, _platyschisma_, _platysomus_, _plaxiphora_, _plectroninia_, _pleioclinis_, pleistocene birds, new zealand, " bivalves, " carinate birds, " diprotodonts, " fish, " foraminifera, " gasteropods, " lobster, " plants, " seal, _plerophyllum_, _plesiastraea_, _plesiolampas_, _plesiosaurus_, _pleuracanthus_, _pleurodictyum_, _pleuromya_, _?pleurostomella_, _pleurotoma_, , , _pleurotomaria_, , , , , _plicatula_, pliocene moa, new zealand, _pliosaurus_, _plotus_, _podocarpus_, _poecilodus_, _?pollicipes_, polychaeta, , _polycotylus_, _polymastodon_, _polymorphina_, , polyplacophora, _polypora_, polyprotodontia, _polystomella_, polyzoa, characters of, , " subdivisons of, polyzoal limestone, _porcellia_, porcupine fish, , _porina_, _porphyrio_, _portheus_, _poteriocrinus_, prehensile rat-kangaroo, preservation of fossils, _primitia_, , _pristisomus_, _procoptodon_, _productus_, , , _proechidna_, _proetus_, , _progura_, _prosopon_, _protaster_, _protocardium_, _protopharetra_, _protoretepora_, _protospongia_, , protozoa, characters of, , , _psammechinus_, _pseudamaura_, _psilichthys_, pteridophyta, characters of, pteridospermeae, characters of, _pterinea_, , _pteris_ (_pteridium_), pteropoda, , , , _pterygotus_, , _ptilograptus_, _ptychoparia_, , _pugnellus_, _pulvinulina_, purbeck marble, _purisiphonia_, _purpura_, radiolaria, characters of, , " habitat of, " structure of, " subdivisions, rail, raised beaches as distinct from middens, _ranella_, range-in-time of fossils, _raphistoma_, , rat-kangaroo, _receptaculites_, regular echinoids, _reinschia_, reptiles, fossil, " dentition of, " structure of, _reteocrinus_, _retepora_, _reticularia_, _retiolites_, , _rhacopteris_, _rhinopterocaris_, , _rhipidomella_, _rhizophyllum_, _rhodocrinus_, _rhombopora_, _rhynchonella_, , , rhynchota, _rhynchotrema_, _ringicula_, _risella_, _rissoa_, _rissoina_, _rostellaria_, _rotalia_, , rugose corals, _saccammina_, _saccocaris_, _sagenodus_, _salterella_, sandstones, _sanidophyllum_, _sarcophilus_, , _sargus_, _scala_, , , , , _scalaetrochus_, _scaldicetus_, _scaphella_, _scaphites_, scaphopoda, _scenella_, _sceparnodon_, _schizaster_, _schizodus_, _schizophoria_, _schloenbachia_, _scutellina_, sea-beds far from the present coast, sea-bream, " -cucumbers, " -firs, , " -mats, , " -pen, " -urchins, , " characters of, sedentary worms, _seguenzia_, _selenaria_, _semele_, _semicassis_, _seminula_, _semionotus_, , sepioidea, _serpula_, serpulite limestone, _sertularia_, , shales, sharks, , , , shell-limestone, _shumardia_, _sigsbeia_, siliceous rocks, silicified wood, _siliquaria_, silurian bivalves, " brachiopods, " brittle-stars, " cephalopods, " cirripedes, " conodonts, " corals, " crinoids, " foraminifera, " gasteropods, " graptolites, victoria, " hexacoralla, " octocoralla, " ostracoda, " palaeechinoids, " phyllocarida, " plants, " radiolaria, " sponges, " starfishes, " stromatoporoids, " trilobites, _siphonalia_, _siphonia_, _siphonotreta_, sirenia, _sistrum_, slate, smith, william, smittia, _solarium_, _solenocurtus_, _soletellina_, sphaerosiderite, _sphenopteris_, , _sphenotrochus_, , _sphenotus_, , _sphyrna_, _spirifer_, , , , , _spiriferina_, " -beds, _spirillina_, _spirorbis_, _spirula_, _spirulirostra_, , _spisula_, _spondylostrobus_, _spondylus_, , , sponges, characteristics of, , _spongilla_, _spongodiscus_, _spongophyllum_, spoonbill, spore coal, _squalodon_, _stacheia_, star-corals, starfishes, characters of, , _staurolonche_, _stauroneis_, steno, _stenopora_, _stenotheca_, _stephanella_, _stephanograptus_, _stephanotrochus_, _sthenurus_, sting-ray, _stomatopora_, storing fossils, stork, strata, superposition of, " vertically arranged, stratigraphical series, general thickness, stratigraphy, _strepsodus_, _streptelasma_, _stricklandinia_, _stromatopora_, , _stromatoporella_, , stromatoporoids, , _strombus_, , _strophalosia_, _stropheodonta_, , _strophonella_, _struthiolaria_, _studeria_, _sturtzura_, _stutchburia_, stylasterids, _subemarginula_, submerged forests, _sunetta_, superposition of strata, _synaphe_, syndactyla, _synedra_, _syringopora_, _syringothyris_, _tabellaria_, _taeniopteris_, , , , , _taniwhasaurus_, _taphaetus_, tasmanian devil, , " wolf, , tasmanite, _taxocrinus_, _tellina_, , , _temnechinus_, _tentaculites_, , , _terebra_, , , , _terebratella_, , _terebratula_, _terebratulina_, , tertiary ironstone, _tessarodoma_, tetracoralla, tetractinellid sponge, , _tetragraptus_, , _textularia_, , _thalassina_, thallophyta, characters of, _thalotia_, _thamnastraea_, _thinnfeldia_, , , _thurammina_, _thyestes_, _thylacinus_, , _thylacoleo_, , time-range of fossils, _tomodus_, toothed whales, torbanite, _torlessia_, _trachyderma_, , _trachypora_, _trematonotus_, _trematotrochus_, , trepostomata, _tretocalia_, triassic bivalves, " brachiopods, " cephalopods, " crinoids, " fishes, " foraminifera, " labyrinthodonts, " ostracoda, " phyllopoda, " plants, " reptiles, new zealand, _tribonyx_, _tribrachiocrinus_, _trichograptus_, _tricoelocrinus_, _trigonia_, , , , , _trigonograptus_, trilobites, habits of, " structure of, _tritylodon_, , _trivia_, , _trochoceras_, _trochonema_, _trochus_, , , _trophon_, _truncatulina_, , _tryplasma_, tuatera, _tudicla_, tunicata, _turbo_, , _turrilepas_, , _turritella_, , , , , _turritella_ -limestone, _tylosaurus_, _tylospira_, , _typhis_, _uncinulus_, _unio_, , _unionella_, upper cambrian trilobites, " cretaceous bivalves, " cretaceous brachiopod, " cretaceous cephalopod, " triassic fishes, " ordovician graptolites, new south wales, " ordovician graptolites, victoria, _urasterella_, _urosthenes_, _vaginella_, , _vaginulina_, _valvulina_, , _venus_, , , , vermes, characters of, _vertebraria_, vertebrata, characters of, , _verticordia_, _vetotuba_, _voluta_, , , _volutilithes_, , , _volvox_, _volvulella_, warrnambool footprints, werrikooian bivalves, " gasteropods, whales, white coal, _wilsonia_, wombat, , worms, fossil, , worm-tracks, wrasse family, _wynyardia_, xenophanes, _xenorhynchus_, _xestoleberis_, _xiphosphaera_, _yvania_, _zaphrentis_, _ziphius_, index to australasian localities. appended letters indicate the state or country:-- n.s.w., new south wales; n.t., northern territory; n.z., new zealand; q., queensland; s.a., south australia; t., tasmania; v., victoria; w.a., western australia. adelaide, s.a., aire coast, v., airly, n.s.w., alice springs, s.a., altona bay, v., arcola, q., arcoona, s.a., ardrossan, s.a., , bacchus marsh, v., , balcombe's bay, v., , , bald hill, v., barker gorge, w.a., , , barraba, n.s.w., , batesford, v., , , , baton river, n.z., , bay of islands, n.z., beaumaris, v., , , , , , , , bendigo, v., , , , berwick, v., bindi, v., , , , bingera, n.s.w., boggy creek, v., bowen river, q., , , bowning, n.s.w., , , , , bowral, n.s.w., brighton, n.z., , , broadhurst's creek, v., broken river, n.z., , broken river, q., broome, w.a., brunswick, v., buchan, v., , , , , , , , , , , bulla, v., bungonia, n.s.w., burdekin, q., , burnt creek, v., burragorang, n.s.w., camperdown, v., canobolas district, n.s.w., canowindra, n.s.w., canterbury, n.z., cape liptrap, v., cape otway, v., , cape palliser, n.z., cape paterson, v., , carapook, v., caroline creek, t., casterton, v., castlemaine, v., , cavan, n.s.w., cessnock, n.s.w., chatham ids., chillagoe, q., chinchilla, q., clarence town, n.s.w., , cliftonwood, n.s.w., clunes, v., cockatoo id., n.s.w., collie, w.a., collingwood, v., coole barghurk creek, v., cooma, n.s.w., , copeland, n.s.w., corio bay, v., corner creek, q., croydon, q., , curiosity shop, n.z., , curlewis, v., , curramulka, s.a., , , , currowang, n.s.w., dalton, n.s.w., , dargo high plains, v., darling downs, q., , , , , darling river, n.s.w., , darriwill, v., delegate river, n.s.w., derrengullen creek, n.s.w., diggers' rest, v., dolodrook river, v., , dromana, v., dundas co., v., east maitland, n.s.w., elizabeth river, s.a., fanning river, q., farley, n.s.w., , fernbrook, n.s.w., fifield, n.s.w., flemington, v., , , , , flinders, v., , flinders river, q., , , , , florentine valley, t., , fraser's creek, v., gascoyne river, w.a., , , , , geelong, v., , , , geilston, t., gellibrand river, v., geraldton, w.a., , , gippsland lakes, v., , gisborne, v., glenelg river, v., glenwilliam, n.s.w., goodradigbee river, n.s.w., goonoo, n.s.w., gordon river, t., gosford, n.s.w., , , , grampians, v., grange burn, hamilton, v., , , , , greenough river, w.a., , , grey river, n.z., grice's creek, v., grose vale, n.s.w., gulgong, n.s.w., , gunning, n.s.w., haddon, v., hallett's cove, s.a., hall's sound, papua, hamilton, n.z., hamilton, v., , , , , , , hamilton river, q., hatton's corner, n.s.w., , heathcote, v., , , hobart, t., , hokonui hills, n.z., , hughenden, q., , iguana creek, v., irwin river, w.a., , , , island of timor, jenolan caves, n.s.w., , , kakanui, n.z., kamileroy, q., keilor, v., kent's group, t., kilmore, v., , , , kilmore creek, v., kimberley, w.a., , , , , king island, t., , , king's creek, q., kirrak, v., knocklofty, t., knowsley, v., koroit, v., kowhai river, n.z., lake callabonna, s.a., , lake connewarre, v., lake eyre, s.a., , , , lake frome, s.a., lancefield, v., , , , , laurie's creek, s.a., , , lawson, n.s.w., leichhardt river, q., leigh's creek, s.a., lennard river, w.a., lilydale, v., , , , , , , , , , , limeburners point, v., limestone creek, glenelg river, v., limestone creek, yass, n.s.w.; , loddon valley, v., lord howe id., loyola, v., , , , lyndhurst, n.s.w., maddingley, v., mallee, v., , , , , mandurama, n.s.w., , , manly, n.s.w., mansfield, v., , , , , marathon station, q., maria id., t., maryborough, q., , , maryvale creek, q., mcmahon's creek, v., melbourne, v., , , , , , mersey river, t., , , milburn, n.z., mitchell downs, q., mitta mitta river, v., molong, n.s.w., moonee ponds creek, v., , moorabool river, v., , , mornington, v., , , , , , , mosquito plains, s.a., mount angas, q., " buninyong, v., " gambier, s.a., , , , , , , , " lambie, n.s.w., " macedon cave, " potts, n.z., " victoria, n.s.w., " wellington, v., , , , " wyatt, q., muddy creek, hamilton, v., , , , , mudgee, n.s.w., muree, raymond terrace, n.s.w., murray river cliffs, s.a., , murrumbidgee river, n.s.w., , , napier range, w.a., narrengullen creek, n.s.w., nelson, n.z., , , , , , , newcastle, n.s.w., ngapara, n.z., nimbin, richmond river, n.s.w., norseman district, w.a., nugget point, otago, n.z., nungatta, n.s.w., nyrang creek, n.s.w., oakey creek, n.s.w., oamaru, n.z., , orakei bay, n.z., otway coast, v., pakaraka, n.z., papua, , , , , , , , , , paroo river, q., peak downs, q., penola, s.a., petermann creek, s.a., phillip co., n.s.w., pine creek, q., pitfield plains, v., pitchery creek, q., pokolbin, n.s.w., , port campbell, v., port darwin, n.t., , port stephen, n.s.w., preservation inlet, n.z., ravensfield, n.s.w., reid gap, q., richmond downs, q., richmond river, n.s.w., rock flat creek, n.s.w., rockhampton, q., , , , , , , rough range, w.a., , sale, v., san remo, v., sebastopol, v., seville, v., , shakespeare cliff, n.z., southland, n.z., south yarra, v., , , , , , , spring creek, torquay, v., st. peter's, sydney, n.s.w., stanwell, q., stockyard creek, n.s.w., stroud, n.s.w., studley park, v., , sunbury, v., table cape, t., , , , , , talbot, v., talbragar, tallong, n.s.w., tamworth, n.s.w., , , taranaki, n.z., tempe downs, s.a., , , thompson river, q., thomson river, v., tinderbox bay, t., tingaringi, n.s.w., toongabbie, v., , torquay, v., , , , , , tyer's river, v., , upper finke basin, s.a., upper yarra, v., , , , vegetable creek, n.s.w., waihao, n.z., waikari river, n.z., waikouaiti, n.z., wairoa, n.z., wairoa gorge, n.z., , waitaki valley, n.z., walhalla, v., , , wandong, v., , wanganui, n.z., wannon river district, v., , waratah bay, v., , , warburton, v., warrnambool, v., , , , waurn ponds, v., , , , , , wellington valley, n.s.w., , , well's creek, n.z., west melbourne swamp, v., westport, n.z., wharekuri, n.z., white cliffs, n.s.w., , , , , , whittlesea, v., wilberforce, n.z., wilcannia, n.s.w., wirrialpa, s.a., wollumbilla, q., , , , , , , wombat creek, v., , woori yallock creek, v., wormbete creek, v., wynyard, t., yan yean, v., yass, n.s.w., , , , , , , , , , , , yering, v., yorke peninsula, s.a., yule id., papua, , , zeehan, t., * * * * * [illustration: australia _shewing chief fossiliferous localities._] * * * * * corrigenda. page , for head-line "_protozoa_" read "_how fossils are found_." page , for head-line "_characteristic fossils_" read "_sea-urchins_." page , for head-line "_reptiles_" read "_amphibians_." [transcriber note: these changes were not utilized here as they only apply to the titles at the top of the printed pages.] * * * * * erratum--page . _in st column_--_for_ "mesozoic or secondary (continued)." _read_ "palaeozoic or primary" and omit divisional line. [transcriber note: these changes were applied to the text.] * * * * * transcriber note images were moved so paragraphs were not split. minor typographical errors were corrected. hyphenation was standardized to the most prevalent form utilized. as the æ ligature was only used five times and "ae" was used more than times, the ligature was converted to "ae". "sterminator vesevo" matilde serao "sterminator vesevo" (vesuvius the great exterminator) diary of the eruption of april . [illustration: logo] naples francesco perrella, editor (_copyright_) naples--print a. trani. _in translating this book by matilde serao, i have felt as if none of its beautiful local colour, of its warmly felt and vivid description should be altered by an attempt on my part to give to its pages a perfect english intonation. one thing would have been, unavoidably, the loss of the other, as no language can render in all its truth and form, the warm and deep expression of southern italian imagination and sentiment. thus, this diary retains the deep impression of the moment in which it was written, while the bold strokes of colour and the tender pathos of some of its pages, bring, once more forward to public admiration, the brilliant name of italy foremost woman writer, matilde serao_ _the translator_ l. h. friend and reader, do not ask of these pages the prestige of art or the fascination of stile. they were written day by day, with a trembling heart, and with an emotion that often caused the pen to drop from the hand of the tired and distressed writer. they were written, each night on returning from the country where the exterminating fury of the mountain had destroyed men and things, and while still under the horror of the terrible vision. thus, rather than a cold literary dissertation, my reader, you will find in these pages, the simple, deep and tragic story of the eruption, witnessed by my own mortal eyes. you will find tales of heroic people, and noble deeds which deserve to be recalled and exalted. my friend and reader, these are pages of sorrow and distress, and they are written with a sincere heart. nothing else. naples--may . matilde serao quia pulvis es ... [illustration: decoration] it all happened very suddenly, just about half past two, while the last smart equipages were hurriedly driving to the campo di marte. in a moment a huge brownish cloud, pushed by the wind, arose from vesuvius, spreading all over the sky, hiding the white light of the day, darkening the sun. an immense cloud which wrapped all the mountain in a black thick smutty shade, and fell dark and menacing on the green carpet of the race-ground, and on the brilliant gathered crowd. a strange curious, indescribable spectacle it was indeed, bringing to mind, as through an extraordinary vision, the feast-day when pompei was destroyed and the people were crowding at the circus. a spectacle both powerful and mysterious, with the strange contrasting effect of the select and gay crowd merrily circulating, on the spacious grounds. then, all at once, to everybody's wonder, cinders began to fall, quite a rain of fine dusty ashes, gradually increasing into a regular shower. a whole array of elegant sun-shades were soon spread-open, and a general transformation took place all around. ladies' white dresses became grayish almost black, dark clothes took instead a lighter almost whitish hue, white hats looked as if powdered all over, while all the roses, the innumerable roses on the hats were thickly spread with ashes, as if the «memento homo quia pulvis es», had been pronounced on them. tears brought on by the caustic rain were in everybody's eyes, though, all smiled fearlessly and gayly. the duchess of aosta's black dress looked as if a gray gauze had been spread over it; every man, every officer, the most elegant young men, the smartest sportsmen were not to be recognised. as for the beaver hats, their condition was indescribable. and ashes, ashes on the coaches, on the autos, on the houses, ashes everywhere! at a certain moment however, the wind changed, the heavy cloud became lighter, the sun took leave from the dying day, and the pale azure sky smiled again on us. and nothing could be then more curious to look at, than all those people, all those equipages, all that scenery, bearing the signs of a strange and rare telluric phenomena. yet, with the exception of servants, chambermaids, and coachmen, who naturally had hard work on hand brushing, washing and cleaning everything, nobody seemed preoccupied. as for the undersigned, a victim of her duty, while she is writing, ashes are falling thickly over her hair, shoulders, paper, and every object around her. april . towards the city of fire all night long, hour after hour, we have had more and more alarming news from vesuvius, and a rain of cinders in the late night, has increased the terror in everybody's mind and heart. the morning is profoundly sad with its still dark sea, with all the streets so black, with that strange sense of anxiety and surprise, among those we meet. the duke of aosta has set off for boscotrecase, cardinal prisco has gone also there, and later, the duchess of aosta has followed. it looks as though a whole crowd was starting out for that town. all carriages seem to go in the same direction, towards the circumvesuviana station. the tramways are loaded! what are we doing here, why don't we start like all the others? let us go, and see these deserted, and destroyed countries, let us go and see boscotrecase threatened by the monstruous lava ready to burn it up. let us run to see torre annunziata threatened by the same, let us go to hear the desperate weeping of women, the screams of children, the moans of the old people. in the train, in the train, for it is too slow going by carriage. let us go like thousand of people have gone, in the train, since we don't possess an automobile which could help us to fly on the main roads, way up yonder, where destruction takes place. in the train, in the train! it is easier said, than done. an immense crowd of people anxious to start, are seiging the station of the circumvesuviana, and the most extraordinary scenes naturally happen, since, if this beautiful and fine railroad, girdling vesuvius, carries generally about a thousand persons a day, it cannot transport to-day fifty thousand. and really it has already worked wonders, due of course, to the energy, calm, and tact of mr. e. rocco, and director ingarami. it has worked wonders, doubling and multiplying its trains from dawn to mid-night, each of them starting with their platforms packed, with their cars jammed with people, standing the most impetuous assaults at every small, intermediate station. for whole bands of foreigners, are waiting in these small stations, and they rush in to take whatever seat they may find. here all species of neapolitans are coming, the best known as the least: groups, coteries, families, parties of friends, who like an immense human legion intend to go to boscotrecase. and little by little, with the young foreign girls attired in their short excursion dresses, their hats covered with large white veils, with the elegant and loquacious neapolitan ladies, with the friends and acquaintances which one meets, with the continuous screaming and yelling, now stronger, now softer, with the most extraordinary buzz of conversation, the sense of fright and anguish gradually dies away. the big cloud of ashes which wrapped us up in the beginning of the trip, disappears after bellavista, the sky is getting clearer, and of a delicate azure colour. in the train people begin to joke, and at s. giorgio a cremano, a whole company of young girls, jesting and laughing, gets up in our train. and now this immense torrent of humanity running towards boscotrecase, looks almost like a large pleasure excursion. one would think that merry and thoughtless life had had the best of fright. and what fright! the main-road going from torre annunziata to boscotrecase, is getting dark, almost black with carriages and automobiles. one of these is coming down from boscotrecase. there are friends in it, and the train having stopped, we ask them what is the latest news. "the lava has stopped", they cry, shaking their heads and shoulders as if disappointed. in the train people are getting altogether merry. a big crowd of people coming down, meets at boscotrecase a still bigger crowd going up, with a confusion of carriages, wagons, automobiles, byciclets, all moving towards that fine country, so richly surrounded, by farms, vines, gardens, and which seems still so calm under the grasp of its terrible enemy. and the people coming down describe with gesticulations, and impressive words, what they have seen not very far off, and they look all excited as though they had witnessed a grand and incomparable spectacle! the crowd moves on, then stands still for some time, for there is no place for it, in the beautiful little town. the peasants of boscotrecase stand around the tourists, silent and still. nobody is crying, no sad faces are to be seen, no complaints are to be heard, nobody asks or pretends to ask for anything. a liturgic sound reaches our ears at a cross path off the road, and a general silence is made in the thick crowd. a rough wooden cross appears, and behind it, over the heads of the people, an ancient statue of s. anne, the protectress of boscotrecase, the madonna's mother. s. anne, the powerful old woman, as these southern people call her, is seen. this statue must be very ancient. it has a thin face, crowned by locks of white hair, the thoughtful face of an old woman bending down on the fresh and young face of a little girl. the statue moving on, waves over the crowd. it was taken out yesterday from the church of the oratorio, which is near b. quite close to the lava, and it has been left there, on the very extreme spot where the lava was rapidly advancing, in the direction of boscotrecase. this morning, at ten o'clock, this first lava has stopped ten meters from the statue of s. anne, while the other branch on the right, stopped half an hour later. far away in the country, five or six farm houses, abandoned two days before, have been surrounded by it, fortunately they were empty, without even furniture in them. but boscotrecase is safe, and s. anne carried in triumphal procession, enters the town. the women sing softly some religious verses while walking behind the statue. there is a certain sadness in their voices. many kneel down and pray, men lift their hats. the old statue of the thoughtful woman, looking calmly to her daughter, is above the crowd. foreigners look with interest, and the sceptic, and those who have no faith dare say nothing, for really, the lava has stopped this morning, at a certain distance from s. anne, and if this fact is due to nature, these people don't care, all they want to know is that they have been saved once more, by the prayers of the protectress. now, a priest speaks to the people, begging them to be calm and hope in god's help. this priest is very fervent, he has been preaching and speaking for two days, advising his people to be calm! this morning he has spoken before the lava. the statue descends slowly towards its church, having done its work of charity. automobiles are rushing every where, whips are cracking, torrents of people push on. bosco is black, the country is black all around, swarms of men and women rush down, while others come up. we pass by a mound of earth accumulated there for the purpose of deviating, if possible, the lava. near this mound the houses are empty, and the doors open. perhaps this same night, their owners, eluding the watch, will return to sleep in them. i have seen some mattresses brought in these abandoned houses. * * * * * but while we climb up towards the lava, the mouth of vesuvius above our heads, roars and thunders. a great column of white, gray, and black smoke stands erect on the cone, and notwithstanding the full day light, we see through those dark and light clouds, long flames arising as through a veil, and showers of sparkles fall in a mass of fire around the mouth, towards our right. the mountain thunders, and breathes as a colossus, it sparkles terribly, dashing stones of fire, masses of fire, rocks of fire every where. the merriness of the trip seems subdued, and the frivolous chattering is hushed altogether. people going towards the lava walk in awe, and silent wonder. every path either steep or easy, is now getting black with people. but in the great silence of this crowd, in that immense silence, only the roaring of the vulcano tells the story of this great telluric cataclism. are we not feeling, perhaps, the earth trembling under our steps? the mountain lightens in flames, getting redder and redder, more brilliant and dazzling every moment. here in this great valley, once formed by another eruption, here were vines, and olives grew on old lavas of remote times, here is the lava of yesterday. amazing spectacle! the gigantic black mass rises powerful and straight, quite at a few steps from us, and it looks like a dark sea petrified in its foaming waves, a stormy black sea, magically transformed in stone or rocky substance, a hardened, dead sea. ah! why isn't it dead? fire and flames are still living within, and now and then it blazes, burns out, shows its incandescence. under our feet the earth is warm, but a little further it is burning. on the right, the other branch of the lava, the one which has still an imperceptible movement, shows a burning furnace under its black and rough stratus, from which masses of fire detach themselves rolling down at our feet, while all around it, large drops of fire fall on the ground, and gradually melt away. wonderful sight! little by little, the fascination of this tremendous thing, of this black and stony sea which once was fire and lava, which is now rock, but still is lava, still is fire inside, seems to fascinate all of us, even the most timid. women, old people, children draw imprudently near, bend over, plunge theirs sticks, their umbrellas in the furnace, with a daring and audacity nearing madness. and vesuvius continues to roar quite over us. way up go the flames of the crater, while night falls. before us the brown and monstruous mass of the two still lavas, rises frightful and menacing. terror seems now to take hold of peasants, gentlemen, indigens, neapolitans, foreigners. a hush of tragedy is over that country of tragedy, with the hardly conjured danger of this night, and the imminent danger of to-morrow. april . a prayer surely, there does not live a pious and tender soul who, in these days of anguish, has not pronounced with intimate ardour, with intimate impulse, some sacred words, imploring the mercy of god on a population struck by such terrible calamity. there lives not a warm soul who, under the shock of this terrible pang, has not felt the need of appealing to a divine power of kindness and mercy. there lives not a cold soul who has not been moved and, has not silently asked for peace, in such a tragic misfortune. oh! yes. let all tender and fervid hearts, all humble and brotherly spirits, all creatures strong with faith and hope, firm in an undoubtful promise, let them ask to the lord, in every conceivable form, the end of this tremendous punishment. it has fallen on too many people, it has devastated too many countries, it frightens now the most sceptic, and the most audacious. let all those who know, who will, who can pray, in the secret of their consciences, of their houses, in the shadow of the churches, all, even those who never pray, those who will not pray, let them ask of god the end of this horrible calamity. it now weighs too heavily, with its terrible unforeseen, with its funestous surprises, with its more and more frightful forms, not only, on those picturesque and thriving villages, extending from the cone down to the sea, but it weighs on naples, on its six hundred thousand inhabitants, and on all the southern region. all italy is trembling with sorrow, listening to the fabulous and yet real story of such a great catastrophe. god of mercy listen, listen to the prayer of all those who pour out their soul to you, who raise their hands to you. listen god of goodness, father of the unfortunate, of the miserable, of the poor, of those who are running away, grant the desolate, desperate, hopeful trusting prayers of those who ask of you the end of this terrible cataclysm. sinners and innocents are begging you oh lord of all charities, children, women, old people, men who have lived too much, and young ones who have not lived enough, and together they implore you to let this tremendous sea of fire, stones, lapillus, and ashes be stopped. they implore you to let this lightning and thunder, these roars, these terrible convulsions of the mountain be ended, oh lord, ended! thousands, hundred of thousands of persons ask for the end of this dream of devastation and ruin! cries, tears, sobs reach your throne oh! lord, do grant the supreme grace, let this terrible destruction end. man is only a poor being of flesh and blood, he is weak, and his mind wonders, and his conscience sinks. oh lord! oh lord! what is happening is much stronger than our courage and patience so unexpected and unheard as it is, so monstrously sad, and irreparable, alas! if you don't help us, oh lord, your children will perish of grief, or will end in untold anguish of despair while those who know, who want, who can pray implore your divine mercy on naples on this splendid coast, and on this sublime gulf. let all those who can think and act fight against this destruction, let them try to master it and to render it less terrible than it is, let the people go not only through frivolous curiosity to the places where the scenes of the vesuvian catastrophe in all their horror are going on, but let them go with eyes of compassion, and earth souls full of charity. do not let this visit to the squalid and deserted villages, to the places where the black mountain of lava is advancing in waves of stone, and in waves of fire, be a sport. don't let it be a diversion or a pastime to relate among friends the sensational scenes which have been witnessed. men of good will, women of good will, each as one may, as one knows, as one must, put your energy, your patience and all your virtues in a sublime effort to mitigate this calamity, to fight it, and, at last, with the help of god and that of men, to conquer it. let every man find all his strength, forgetting himself and his own small, and perhaps miserable interests, and let the sense of charity become heroic in all those who have some will, strength, courage, and valor. let everybody do his own duty and even beyond his duty, and to this terrible catastrophe will then be opposed another amount of will, of thinking and reasoning will. let this panic of the more cultured classes be conquered by influential words, and by the example of all the directing classes; let everybody sacrifice himself, from the prince to the civil functioneer, and let each of them perform those acts of abnegation which are the seal of human fraternity. let cold blood and the stubborn decision to fight the conflagration triumph, and victory will be man's. let this folly of lies, inventions, and exaggerations end, and with it, this infamy of false news printed in some papers with the sole intent to sell them. let those who have some heart show it by advising others to be calm, by consoling the afflicted and the poor, and providing to their material and moral needs! let this heart be demonstrated by all the civic virtue which are necessary in these terrible crisis, and this will be another way to show that they are men, christians, and that they are all bound in a same part of joy and sorrow. th april . in the dead towns to day, our trip towards the countries where destruction goes on, is much sadder and silent. whilst on every side, from every person, from every telephonic communication, from every telegram, the most distracting news reach us, whilst the first impulse is that of starting, of running there where people are suffering, where they are agonizing with fright and sorrow, we all know that the circumvesuviana railway is interrupted, and we understand how difficult it is to go there quickly, or in any useful way. a secret rage is in our heart against this blind and brutal power on which all our arms of civilisation fall and break, and we unwillingly resign ourselves to go as we can, just where the lava permits us, where the eruption allows us, where vesuvius wishes, and no further. we leave naples by carriage, in the afternoon. the city has a depressed look, and is unusually quiet. while we cross from ponte della maddalena to s. giovanni a teduccio, the last people on the road disappear. only now and then an automobile passes us, but the people inside are quite hidden under their wraps and masks. then an old dirty char-banc rolls by, then again a loaded tram, but nobody is laughing, nobody is speaking. all along the streets, on the sidewalks, in the shops, silence is getting deeper, and more intense. true it is sunday, it is four o'clock, the hour when people here rest, but the silence is still more intense at portici, and its closed villas, its closed shops, have a singular aspect. now and then something moving comes towards us, directed to naples. it is a little cart, two little carts, several carts, all loaded with furniture, especially with mattresses. a silent driver leads the wagon, and we turn round to look at these last people escaping, for in these last fifteen hours everybody has been running away with his furniture, in all directions, especially towards naples. these whom we meet must have been delayed in their flight, they are worn out from exertion, and almost prostrated. portici is deserted and solitary, not a single woman at the window, not a person before the houses. hall doors and shutters are locked, and the most absolute emptiness and desertion reigns every where. our mind is getting depressed, and our sadness increases when we see the complete solitude of resina and torre del greco, the lovely little towns layed between gardens of orange trees, and the sea. it is indeed a heart-rending squallor! the charming towns of portici, resina, torre del greco, are now completely abandoned, not a soul is left there. they look as dead towns, quite as if dead and deserted since many and many years--nobody is there to tell us the panic, the terrible panic that has set these people flying for safety, but we know it, we can easily imagine it since we see with our mortal eyes, abandon and death every where. but did resina, portici, and torre del greco, ever live? did these windows, these doors ever open? were there ever people in these houses, in these streets? like an immense colossus the pine of smoke rises on the mountain, and everything is shut out from our sight on account of the ashes, clouds, and vapors filling the air. only the lightning is visible, the thousand flashes cutting the livid and opaque gray. and life is only there on the mountain of horrors, whilst here nothing more is living. * * * we now wonder whether we shall still find torre annunziata the same thriving town, full of energy, work, and action, torre annunziata of which we are so proud, which is a glory of ours, since its life has a great importance, and its population is good active; and very laborious. this is our hope as we enter it. alas! here are some wagons coming with furniture, and there is a sick man, an old man on a mattress, laying in a small carriage. they are all slowly moving towards naples. yes also torre annunziata is dead! all the houses are closed, all the working shops are deserted. foundries, manufactures, establishments, all is closed. never could we have believed that in a single hour, in a short hour of desperate panic, all this could have happened, and that this town this magnificent instrument of work and industry, should be stopped and destroyed like the pines up yonder, in the great valley of the oratorio at boscotrecase. at mid-night, the nine tenth of the population, at the terrible cry that the lava is advancing towards the city, begin to escape. in one single night , people have abandoned their roof, have gathered their dear ones, their goods, and have fled to nocera, castellamare, sarno, salerno, naples, calabria, basilicata. all have fled in one single night. but why? and how has this possibly happened? men of the people in silent groups, hardly answer our queries; they simply point to a street towards which people, alighting from carriages and autos, direct their steps. the lava is there, much nearer than that which stopped outside boscotrecase the other night, and which invaded it altogether later in the night. the lava is yonder, on the livid background, darkened by the clouds wrapping up the mountain, there where a large white smoke arises, pushed by the wind. it is the road which leads to boscotrecase, the same road which day before yesterday, while laughing and jesting, we saw full of carriages, cabs, and merry people. now, all is changed. from that road the lava has come down. the great white smoke leads us, while the wind blows harder. we see trees bending down, they are cypress, the rich cypress of the cemetery of torre annunziata, one of the neatest, most poetical cemeteries i ever saw. and the monster is here, quite near. the lava is here, its scorching monstruosity is here, in front of the cemetery, but somehow it has branched out, it has not touched the ground sacred to the dead. it comes down in deformed and grotesque waves, wide, high, incandescent on the sides and on the edges, it has unwalled a house, it has destroyed the railway of the circumvesuviana but, happily, it has not touched the cemetery. a dead silence reigns among the people grouped on the low walls, on stone piles, behind the gates, and all gaze at the lava, at the monster, but thank heaven, the picturesque cemetery is still untouched. but what will happen in the night what will happen to-morrow? can't the dead rest even under the ground, and they who will want to pray to-morrow on the tombs of their dear ones, will they be obliged to realize that a new mound of earth, and this time of fire, has buried them, and their graves, for the second time. in the country of death going towards somma while we run at all speed with the elegant automobile a kind friend has lent us towards the other vesuvian countries not touched by the lava, but about which all kind of sad reports reach us, we hear on all sides the same selfish expressions, the same striking, and wounding words. where are you going? where do you wish to go? are you mad? you cannot go any farther up, there is lava, there are stones, lapillus, ashes! that country is destroyed! the other side is surrounded! you are mad! but though irritated, annoyed, offended by this superficial and selfish talk, we go on, we advance towards cercola, sant'anastasia, the madonna dell'arco, following the tracks of the royal automobile, as the king and queen have climbed up there before us, and have already come back. we cannot believe that we may not reach somma, or that somma is destroyed; we do not believe that one cannot get to ottaiano by some means at least, even if this pretty and rich little town is destroyed as people with a half ironical, half resigned smile, tell us, unwilling as they are to go, and give their help. ah! sure, we poor writers of human troubles can do but very little, but we want to see this sorrow with our own eyes, we want to relate it that it might touch the heart of people to heroism and pity, and we want to relate it just as it is, just as it exists, by personally witnessing everything, as we have always done. on this road that goes to somma, other people have passed an hour ago, and we also want to go over it all, even through ashes and lapillus, over the stones, just as we can, by carriage, on foot, any-way. as we advance we begin to see all over the country around us, something like a mantle of snow. has it snowed on the fields, on the trees? no, the vesuvian ashes, with the rain and the dew, have already changed into chlorate of ammonia, and all is now white and brilliant under the pale rays of the sun. here on the right, behind the mountain of somma, things have taken a dark, livid aspect. an immense cloud of ashes and smoke is bending down over the hidden cone in the direction of torre annunziata, resina portici, and night seems to reign there. here instead, all is clear, all is candidly white. our automobile is now going slower, it cracks between two deep sinks of ashes and lapillus. the wheels are now beginning to sink, and at the first little houses of somma vesuviana we stop, and ask the people if the king has passed. yes, yes, the king has reached somma vesuviana with his automobile, and has insisted on continuing to ottaiano, but the automobile having been caught and sunk in the ashes and lapillus, it has been impossible to advance. he has insisted on going on foot, but it would have been at least a four hours' journey. the carabineers have tried to push, the royal automobile with their arms, but without success. then the king has decided to go back. and now, in the great solitude of this grand landscape, in the silence of things, we are really struck by the idea that something terrible must have happened up there, and that the disaster may come near being, what it was one day at pompei! at somma vesuviana we leave our automobile. two other large empty ones watched by a chauffeur, are here. one belongs to the duke of aosta, who has come here this afternoon with count d'aglié and lieutenant gaston pagliano proceeding with them on horseback or on foot to ottaiano or s. giuseppe di ottaiano, knee deep through ashes, stones, and lava. the other automobile belongs to the duchess or aosta. this brave and courageous woman has reached this place a little later, and has gone to ottaiano on foot, not caring for the enormous difficulties and fatigue she would encounter. while we are trying to imitate her, here is all the population of pretty somma vesuviana around us: men, women, children, crowding, and putting to us a thousand questions, while we, answering, address just as many to them. digging up the earth they show us the three stratus forming the mound that has covered their little homes and fields. three stratus, a reddish one, a blackish one, and one of stones, alas! just like pompei. women with babies in their arms speak slow and low, and mournfully complain of their fate. they have, had, as they say, three nights of hell: the first all lightning and flashes, when their terror has been terrible, though they thought they were protected by the great mountain of somma, and no lava would run down on their side. the second a night full of fright and ruination, and the third, the one between saturday and sunday, when the terrible rain of ashes, lapillus, and stones, began. they have fled terrified through their farthest fields, way down as possible. the most courageous have past the night in the open air, with their children around them, trembling with fear praying, and weeping. next day they have been wandering around their houses, trying to free them from the weight of the cinders and stones, helping each other, simply resigned and abandoned to their fate, trying all the means to conquer it. the third night, the last one, they have all slept with their poor little ones, clasped in their arms, on the straw, in the fields, not daring to go back into the houses. men and women are now looking at their buried fields, their destroyed harvest, the heavy cinders, the heavy rocks. they look at the work of this night which throws them in the most abject poverty and starvation, they look over it all with eyes of calm despair, and it seem to me a shame for the human heart that they hope nothing, and ask nothing from the men of naples, their brothers in god, their brothers in jesus. they ask nothing, because they know of obtaining nothing. at somma vesuviana one man has died in margarita street. an old man by the name of raffaele, known as tuppete, he died in his bed, crushed under the fall of his roof. twenty or thirty houses have tumbled down at somma vesuviana, one church is in great danger, the walls of another are cracked. men bend their heads and are silent, others sadly admit that their misery is nothing compared to the destruction of ottaiano where more than one hundred and fifty people have died. has ottaiano then been destroyed only by the fall of lapillus and stones? surely the lava cannot run on it, as the town is placed on the opposite side of the eruption.--have really so many people perished under this heavy and fiery rain, while not one has perished under the lava? is it pompei again? let us go there then, if it is true. at ottaiano here we are on the road of the croce, going step by step, with the slowness of death, sinking deep in the ashes, and looking in vain for a safer path. we go over it with a sense of immense oppression, not knowing when or whether we will arrive, not knowing if our strength will last until we get there. we meet a cart coming down. the poor horse is already tired. it would take at least three horses to drag a carriage through these roads now made of ashes and stones. the cart driver tells us about the many people who have perished at ottaiano and shakes his head when we ask him the number. it is large, many people were killed while praying in the oratorio of san giuseppe! crushed under the weight of our sorrow, we resume our walk on the road of the croce, where so few people have passed before. only a prince of casa savoia, only a daughter of the house of france and the soldiers of italy, the brave soldiers the good soldiers, have come this way. what time is it when we reach ottaiano? who knows? who knows anything more about the hour, about time, about life, in these last four days? we feel as if we had been walking for centuries in this hard, rough, horrible street: we feel as if we had to stop at every step and rest; at last, we reach the new pompei, ottaiano. an untold horror of devastation is around us. the most beautiful as well as the poorest houses have tumbled down under the weight of the cinders and stones, and everywhere you see a precipice of bricks, beams, and rocks: it is the death-like solitude of the places where death has passed. a gentleman from ottaiano, who has just returned here to give some help, tells us all about the catastrophe. it seems that the cinders have begun to fall thickly during the second night from saturday to sunday, and it was then that the people, getting alarmed, have left their houses, the exodus having started about dawn. but in the following morning, the stones have come down thicker and larger, rebounding and accumulating, and, at the remembrance of the horrible scene, and the flight from ottaiano, poor m. cola's voice trembles. he however, with the help of his brothers, managed to save his mother, carrying her in his arms to sarno where she is now, he told us, perfectly safe. it seems that in a few minutes all the panes of the windows were broken, people running away with chairs and tables on their heads, to protect themselves from the rocks, others with folded covers and pillows, shielding their heads, and shoulders. and while they fled on every side, falling down in their haste, wounding their hands and knees under the infernal shower of hissing rocks, the houses at ottaiano, were tumbling down. poor baroness scudieri, while running away, must have heard the crash of her palace, and of the whole manufacture scudieri falling in ruins, while in the same moment on the other side ateneo chierchia, and the house belonging to the brothers cola, just then remoderned, were falling in a heap. what struck us as strange was how, in the midst of so great a ruination, the grand palace of prince ottaiano remained untouched, standing alone and erect as if in mute contemplation of this immense destruction. to nola, sarno, castellamare, marigliano, people fled from ottaiano, and the poorest, finding no shelter, ran about the fields, and over the whole country, as far as possible from the place of the disaster. there must be dead people under these stones. in a house seven persons have been buried, a whole family, and through the door we see the half bust of a man, dead, a poor wretch who must have tried to open it, and escape, just as many did in the catastrophe of pompei! beautiful ottaiano, the finest place in the vesuvian comunes is, sadly to say, destroyed for four fifth, and what remains will have to be demolished, being quite in a dangerous condition. poor abandoned, isolated country, helped by nobody, left to its fate for a whole day and a half. but for the duke of aosta, who went there with his troops, it would have remained in this condition with its dead and wounded for eight days longer. and yet people are returning here and they even dare to go over the road of the croce. here comes a family of peasants on an old broken down char-à banc. the poor mother has a child clasped in her arms, she is as pale as death! the father holds another child, four larger ones are laying on some straw, a real human pile, sad and deserted. we tell them not to return to ottaiano, for their house will surely fall on their heads. but they protest, and declare that they will sleep in the open air, that they want to return among the ruins. the woman is terribly pale, and the children are terrorised. here is a tall thin old man, coming on foot. ah! how he weeps, how he weeps! how sad it is to see an old man weeping. we tell him not to venture in ottaiano, we beg him not to go, and he excitedly exclaims: i want to see, i want to see whether anything has remained of our country, and, he goes in almost stumbling, disappearing into the new pompei. death only this formidable name can be given to ottaiano. from that terrible saturday night, till the following sunday when the first threatening signs appeared, the church bells have been ringing madly and everybody has started to pray. the fall of ashes increasing and getting quite menacing, rev. parson luigi d'ambrosio has requested the population to meet in the church of the oratorio of san giuseppe. how many were they? three-hundred? yes, perhaps three-hundred. the bells continued to ring desperately, as in a frantic appeal, the ashes fell thicker and thicker, down bounded the stones accumulating heavily everywhere, and crushing every thing. all at once, with a tremendous roar, down comes the roof of the church crushing and killing all those who were under it praying. perhaps hundred or eighty people have escaped, running away mad with terror, and among these, fortunately, the rev. parson d'ambrosio has saved his life. but from one hundred to one hundred and twenty persons have been crushed and asphyxiated under the rocks and beams of the old church, and by the enormous quantity of ashes which have buried them. and yet, while they are taken out by our brave and intrepid soldiers, we realize that most of these poor victims, have really died from suffocation. the women are many, and many are the children. but behold! here comes the woman of all goodness and tenderness, here comes the duchess of aosta, led by her tender heart to this country of death. she bends over the corpses and is piously praying over them. then she goes towards a tent where the wounded people have been taken, and speaks kindly to them, encouraging and helping them. how many are the corpses already drawn out from the ruins at s. giuseppe of ottaiano? sixty? there are some more. how many are the wounded? twenty, thirty? the soldiers are still searching and more will be found. as for the people remaining, they are frightened to death from the shock, we must give them bread, and shelter. this, this is really the country of death! there, where the lava has passed, people have fled, where showers of mud have fallen, people have been able to escape, where there has been great danger, help has been brought, like at boscotrecase, torre annunziata, resina, torre del greco, but here, at ottaiano, at s. giuseppe, in this great solitude and abandon, the terrible host, death, has passed. april th . the heroes we shall see, we must see, it is our duty to see later, but not too late, who have been the cowards, the depraved, the stupid men who have dishonored humanity with their cowardice, with their vileness, with their stupidity, in this horrible catastrophe. more especially those who have been discharging public and administrative duties, and have abandoned their posts even when there was no danger. those cowards who did not go where their functions called them, giving all kind of pretexts or excuses, and prudently locking themselves up in their houses. those cowards who, having the greatest duties of civic courage to fulfil, have tried to blame others' courage and valor in order to retain the respect of the public. let all these, and the soonest possible, that is, as soon as this devastation is finished, let all these cowards be denounced to public opinion! we have already heard many of their names, later on more will be called out, and every body will know who are those who muffled their conscience in this terrible plight, and neglected their duties. and we shall also speak of those who have been so degenerated as to turn to their advantage this calamity unexpectedly fallen on an innocent people, and among these speculators of all kind, we shall also place those newspaper men who have set the greatest panic among the people, printing continually false news, increasing (and there was no need of it!) the proportions of this tremendous catastrophe, simply for the greed of selling their papers, the consequences of which have been of the greatest damage to the poor people of those communities, not only, but have made a terrible impression on naples especially, destroying its very life! we shall not spare either those foolish individuals who seem to add to all calamities by their stupidity, who fall among us like a punishment of god, nor those who prevent willing people from working, or acting, in fact who are a real disaster to humanity. and yet it looks as if, of disasters, we had had more than our share! we will speak of all this but not just now, it is not quite time to settle our accounts, we must wait for this terrible conflagration to end! then all those who have been miserably vile, who have been mercenary and stupid, all these people, real calamity of calamities, must be called before a moral tribunal, and must be branded forever before the public. not now! the moment of their judgement will come, must come! * * * but what must not be delayed another moment, is the proclamation, before our whole country, before the world, of those who have been the heroes of this scene of horror and despair. the soldiers have been the heroes, the soldiers are the heroes! from the first of them, emanuele filiberto of savoia, high minded, noble hearted man, from this duke of aosta to whom is due all the organization of rescue, and of forder, from this worthy nephew of victor emanuel the great king, from this very worthy nephew of umberto of savoia, who twenty-two years ago, in the hospitals of naples, helped and tendered the people dying from cholera, from this emanuele filiberto, who is tenderly loved and admired, to the humblest, to the most modest of soldiers, they only and alone have been the heroes of this terrible eruption. not only heroes of courage, but of untiring activity, not only of impulse but of faithfujness, not only heroes before danger, but before fatigue, privations and sacrifice. everything has been done by these brave soldiers in these last five days, beginning with the duke of aosta, who has had no rest, going every where calm and silent, without pomp, without blague, without any useless talking, giving the most efficacious orders with the kindest manners, resolution, and firmness, to general tarditi the illustrious man, the great soul of soldier, full of talent, culture, and valor, down to all the other officers to all the other soldiers. they have defied and conquered the lava, and lapillus, going always ahead there where duty called them. they have looked for the dead and the wounded among the ruins, and they have buried the corpses with their own hands. they have demolished the tumbling houses and built straw-huts for those who were running away: they have divided their bread, yes, their bread, these dear soldiers, with the peasants and women, with the children: they have kept long watches in the most dangerous places; they have given the greatest help there where destruction seemed worse, and all this has been truly heroic! who has gone to boscotrecase surrounded by fire, but the soldiers? who, has gone to ottaiano and to s. giuseppe, from the very first day, when nobody had dared go there, but the soldiers, from the duke of aosta, the majors, the captains, the lieutenants, to the last soldier? who has brought bread to the hungry, and water to the thirsty? who has tried to free the streets, the houses from the ashes and stones? at ottaiano, the sister of one of our newspaper men owes her children's life to the soldiers, who, after having saved them, have fed them, taking the bread from their very own mouths. at torre annunziata, in a desperate moment, when the lava was almost touching the cemetery, i bent over the opening of a wooden fence which closed a large field on which the lava was advancing, and before this great black and red monster, the field seemed deserted! only a soldier, a simple soldier was there in a solitary corner. there he stood before the lava advancing near him: he was there alone, perhaps to keep the little fence from being broken down by the frivolous curiosity of the crowd. here in the barracks the soldiers are sheltering those who are running away, giving them food and courage, and with the same courage and heart, they gather to them all lost children. oh unknown heroes! oh our own heroic brothers! oh! our heroic own sons, here through you, the honor of humanity is saved. for you we are still left to believe that the most admirable virtues can still live in the heart of men. oh you heroes before life and death, heroes for valor and for goodness, you great heroes from your young leader to the generals and officers, all of you martyrs and heroes, our own salvation, our own strength, our own glory, our soldiers! th april . let us speak to the people very eminent prisco, archbishop of naples, sitting on the mystic throne where the great pious soul of sisto riario sforza shone of deepest faith, where the simple and kind soul of guglielmo sanfelice shone with the tenderest religious charity, you, whose loving heart as a minister is certainly aching, you who have already spoken to the people and to the clergy in the name of christ, you who have already helped and promoted help, look very eminent prisco, our archbishop of naples, look at the despair of the people of naples. the calamity which strikes us all, more or less, is indeed tremendous! but its aspect above all has something so dreadfully threatening, to fill even the coldest and most courageous, with a sense of apprehension and awe. these immense clouds now gray, now livid, now reddish now black, towering over our heads, stretching from vesuvius till here, covering the sea, the city, hiding the sun, darkening the air, these clouds, which will later fall in a long and heavy shower of cinders, these clouds which science and experience declares perfectly innocent it is true, and which enfold the whole city, oppressing it, and giving it such gloomy look, are terrifying, and frightening every body. in the first days of the disaster, neapolitans have maintained their usual calm and serenity, but now terror has stricken the most, and has almost grown into a frenzy. we know, of course, that all these phenomena are more terrible in their appearance than in their substance, but the lower classes don't know this, and don't wish to know it, and their fear assumes now a furious dangerous character. through the papers we can do nothing, as the people don't read us, and generally do not know how to read us, neither can government notices stuck on the city walls have any effect on them, since they cannot read them. and yet they seem to go mad, to lose complete control of themselves, they cry, scream, run madly, they yell, they don't pray anymore before the images of saints and madonnas. they have the despair of the child, of the savage, and this very frenzy is a rapid contagion rendering life more desolate and difficult before this calamity. all the most terrible instincts give way before this mad terror. we tremble at this new coming danger, and see no way to conquer it. * * * you, our dear bishop must conquer it. you must speak to the people once more, and with a calm and firm word, tell them that their life is in no danger, that they have nothing to fear from these black clouds sent by the eruption, from the ashes which fall on the streets and on the houses. call your clergy, and tell them to speak to the people, in the churches, in the chapels, in the congregations, in the sacristies. the priests of naples are all very kind, they are quite near to the people for their virtues of christian simplicity, and humility: they know how to make the people love them by the gentleness of their manners, and by that fatherly familiarity which is such treasure among us. set these priests, rectors, parsons, speak to the people, especially in this holy week, when sacred services are so frequent, when, oftener than ever, people go to church. let the rectors, the parsons and all these men of holy moral authority, say to them that they must be calm, and serene, that there is no fear of death, that nobody will die under the lapillus, under the ashes, and that all these screams and moans are not acceptable to god, nor to his saints. let those who always speak to the people from the altar, from the pulpit, from, the confessional, from the sacristies, speak now, using all that influence they possess to control the soul of the most ignorant obscure. let religion glorify itself in this civilised work of peace in the minds of this population. let yourself and your clergy have the merit as christian and as neapolitan citizen, to calm this delirium of fright and give back tranquillity to all this population in confusion. repeat, repeat to these poor people, that for them and their families no danger is to be feared, and people will believe it. let this noble and great, work be one of those beautiful and glorious social events, of which religion has always been and is always capable when any misfortune has befallen to this city. neapolitan people are accused of being superstitious and are despised for this: be it your work and that of the clergy to demonstrate that only faith in its civil form, in its form of high moral beauty, can accomplish certain moral miracles where no other power of mind can reach. april th . to the women of naples women of naples whose heart knows how to beat for all great, noble, beautiful things, oh! women of naples, possessing fervently and efficaciously the great virtue of piety, women of naples, always kind and tender, whatever be your condition, either brilliant or obscure, whatever be your fortune, great or modest, whether god has granted you the supreme goods of life, or whether your life runs its simple and shaded course, you to whom the unfortunate ones never turn in vain, to whom the words of christ, "who gathers to him a poor man, gathers me", are a law of the heart, oh! women of naples, look around you, and see how thousands and thousands of poor unfortunate beings, men, women, and children, your own brethren in christ, have been stricken down by this tremendous calamity. they had a home and they have been obliged to flee from it not to remain buried under its ruins: they had an orchard and it is gone, they had a field and it is all buried under the stones, they had work and they cannot work anymore, they had some kind of industry, and all this is gone! they are poor, exiled people, escaping for life, and notwithstanding all help, notwithstanding the great impulse of charity, they are too many, they are all a population of poor people, of starving people of naked people, and more must be done for them. each of you women, either rich or poor, must open her arms and heart to these poor miserable creatures. for even if they have a shelter, they are often without any bed; if they have a bed, they are perhaps without bread or without clothes. women, neapolitan women, let your help be given in all the possible forms and ways, gather up to your heart these poor unfortunate beings, just as if they represented the figure of christ, and be generous to them in the kindest and noblest of charities. look after these poor people, they are everywhere, in every public institution, at granilis, barracks at the albergo dei poveri, and we cannot do all for them, if you neapolitan women don't give your part in bread, in clothes, in all that is needed to feed a poor man, and to shelter him from cold. neapolitan women, good christians, in these days of mourning, be a heavenly smile to these poor unfortunate ones. good christian women celebrate this easter in the closest brotherhood with those who suffer. * * * have you heard? in granilis barracks from three thousand to three hundred people from the vesuvian comunes, have been sheltered, and among them there is an immense number of terrified and sorrowful women, and little children. there are a great many, perhaps thousand poor little creatures escaped from death in their mothers' arms, in the terrible nights when the storm of cinders, stones, and fire was at its worst.--the noble impulse of the soldiers there, works wonders, and the th infantry is certainly first in this noble and generous hospitality.--in this barrack, the people who escaped from the conflagration have shelter and food, and colonel belluzzi, and his officers are entirely given to this high work of charity. but these poor people have no clothes to change, and the children especially are almost in a naked condition. what can these poor soldiers and officers do to clothe these destitute children? it is your task, neapolitan women, now that you know it to gather up from your house all the coats, dresses, linen covers, all that is superfluous, and send it to the miserable people at granilis barracks. you all have girls and boys, and your children have plenty of clothes they don't wear any more. give them to these unfortunate ones, to these babies who are dear to their mothers as yours are to you! gather up everything you can, bundle it up and send it all to the barracks. all will be useful, everything is useful. also they who have no money to give, have a dress, a shift, a pair of shoes to dispose of, and thus you also, if you are not rich, can show your heart in this useful and simple way. great committees are a great thing, but their work is too slow for too many reasons! without committees, without signing subscriptions, give your motherly charity, give bread and clothes, let it go from your hand to other hands, from heart to heart, at once, just as christ has prescribed. and in doing this noble work, you neapolitan women, will feel your soul expand with emotion and tenderness thinking that each of those little creatures you will dress with your own children's clothes is a little unknown brother to them, and you will bless god to have been able to perform one of the noblest and highest works, one of the highest duties which belongs to our soul. april th . easter of resurrection a few hours after this paper will have reached your hands, my readers, you will hear, in the morning air a sound from afar, or perhaps near, a light and touching sound. and even if in that moment you are quite taken up by thoughts of interest and pleasure, by the cares of a long day, you will start, and a whole crowd of remembrances, perhaps of hopes, will spring out from your heart living in the past, and filled with illusions. thus the easter bells, those which wolfgang goethe, the poet of poets loved and exalted, those which touched the heart of old faust, the easter bells, grave and soft at the same time, will tell you that a whole anniversary of sorrow has started and closed, and that a new spring, spring of triumph has appeared in a glory of light and perfumes, in the large and pure horizons where the spirits live. never before as in this year did the holy week look so dark and sad to all hearts, for it was marred by the desperate cry of those who ran away under the shower of burning stones, by the missing of many frightened children, under the black threatening sky full of flashes and lightnings. never before as in this week, the ancient prodigies which surrounded with their frightful expression the death of christ, the flaming sky, the trembling earth, the torn veil from the temple, seemed to repeat themselves in all their terrible truth. and never before as in this year, the heart of all christians wished ardently, through their warmest prayers, that these sad days should pass quickly away, and that resurrection of life, peace, serenity and joy should console human beings from the deep and terrible things they had experienced. how much sweeter, this morning, in the distance, will these easter bells ring for us all, announcing to us, as a particular grace, the end of a conflagration that has troubled us so much, and brought so many bitter tears to our eyes. resurrection to-day will mean also in its symbolic and yet real language, the end of a week of passion and death, the end of a spiritual and material tragedy which has twice oppressed our tired and worn out souls: resurrection to-day with its slow and subtle bell-sound will mean, to those who were agonising with dread the return of life. * * * well let us live again! let this palpitating city undertake once more its works, its fatigues, its industries, all kind of business, all light-houses of progress: and from its hills, green in their spring dress, not withstanding its vesuvian cinders to its sea so wonderfully calm, in these days let naples live again its magnificent life!--in every order of things let the almost dead organism resuscitate: from the offices to the theatres, from the churches to the schools from the banks to the tribunals, from art places to worldly centers, let naples resuscitate from its week of passion and death. let the existence of six hundred thousand inhabitants proclaim its rights, reacting against a mortal depression, and let, in fact, existence conquer in a better way the incommensurable damages of this week of passion and death. ah no! don't let us forget from one day to the other this terrible cataclysm which only yesterday made us tremble, and the traces of which will never, be effaced again. don't let us forget the dead who slept in that tremendous night, and the living who were deprived of their roofs, bread and clothes.--but in order to exercise the most efficacious discipline in order to be of some relief to the hundred and fifty thousand unfortunate ones of the vesuvian communities, let us live again, let us think, let us wish, act, and work. let the authorities help with wisdom and generosity this new life of naples, making away with all prohibitions, making easy all difficulties of this crisis; untangling one by one, all the knots which obstructed our movements; and let every single citizen develope all their activity, without obstacles, without any stumbling stones. let beautiful naples resuscitate from this day, in all its beauty, goodness, and strength, this unfortunate city which has had its night of chetsemane, sweating blood, but is now a stronger, younger and greater conqueror. let us live again for our country for our families, and for ourselves. let us live again that we may help all our unfortunate brothers to live anew: let us live again in the fervor of actions in the ardor of will towards a great good, not only in ourselves not around us only, but beside ourselves and much farther, towards all those who suffered unjustly and cruelly. the sad trial is finished: the hour of suffering is gone! our soul has been soothed. let us all live again: let us each live for the other! and all for all. april th . four-thousand little boxes how great the irony of things is! since last thursday the fifth of april, when the cinders began to fall from vesuvius, indeed, while they were having the races at the campo di marte, and naples was gay and merry, for the last eight days our post-offices have shipped more than four thousand wooden boxes. at first all this lot of small and curious boxes, carefully sealed, some registered as samples of no valour, others as postal-parcels, seemed to greatly puzzle the postal officers. after a little the strange mystery was revealed, by opening eight or ten of them, as they were not well closed nor well sealed. these singular little boxes contained ashes from vesuvius. more than four-thousand boxes of vesuvian dust have gone and are still going. irony of things! these little boxes are sent as a strange and rare thing, to the farthest parts of the world, even to australia, that the people from every part of the world, may see the vesuvius ashes fallen over naples. till australia! but especially to england and america: and by investigating the matter it has been seen that nearly all those who had shipped the boxes were foreigners. which means that all the foreigners passing through here or established in naples, or who had come here to see the eruption had immediately thought of gathering this dust, put it in little boxes, and send it to their relations, friends, lovers, and flirts. and this has been one of the most interesting points of this sad period: it has been a proof of the coldblood of these foreigners who in a conflagration like this see but the curious side of things. four-thousand little boxes and perhaps more! and we here, feel sad and oppressed by these cinders burying us! how much better it would have been if the little boxes instead of four thousand had been forty thousand! it might have been the means of lessening this danger. april . a woman monday april this has been one of the worst and saddest of the five days of tragic anguish of things, and men. i reached somma vesuviana at half past three, and the automobile which was carrying me, was obliged to stop quite outside the town closed, and over-powered as it was by the new strata of dust and lappillus. then with the companions of this sad but dutiful excursion we have gone on on foot, sinking so deeply at every step, that fatigue seemed and was almost umbearable.--few people peeped out of the doors of their country houses, nearly all covered and hidden under the ashes and lappillus, and spoke of two towns not very near, but not far, quite destroyed; s. giuseppe and ottaiano. these people told us of the dead of the many dead and wounded that were there and insisted before our incredulity. we thought that those poor peasants lied or exaggerated, we did not really believe it, but we hoped it! but alas! they were right and nothing of all that had happened there had been known, till the morning in naples, and we ourselves, had climbed the sad calvary, only through vague presentiment of misfortune. it was quite true that more than three-hundred people lay dead between ottaiano and s. giuseppe. we walked dumb and trembling with deep sorrow, among stones and lappillus stopping now and then as if exhausted. an automobile had stopped in the midst of somma vesuviana, it had found it impossible to proceed, and was guarded by a chauffeur only. two brave carabineers roamed sadly about, and when we asked them whose the automobile was, i was informed it belonged to the duchess of aosta, who having taken her leave from their majesties about twelve o'clock, had gone up to somma vesuviana a little after mid-day. not having been able to proceed towards ottaiano either by the automobile or by carriage or horses since there were none to be had, and quite decided to reach ottaiano, she had started on foot, on a road buried under ashes and lappillus, a road, which in ordinary times can be run over in two hours, and over which she had walked at least for four painful ones. calm and resolute she had not hesitated a moment to undertake that difficult walk, but had gone through the whole way in a simple and silent manner reaching ottaiano all alone on monday th of april, where pale with emotion she had witnessed the unburying of the first fifty dead. then she had given all her cares and attendance to each of the bodies, with her own charitable hands with her kind and sweet words, with the tenderest encouragement to the most unfortunate. and till sun-set in that terrible day in which all the horror of the conflagration seemed worst, since the catastrophe of pompei seemed to be renewed in ottaiano and in s. giuseppe, there among the dead and the wounded stood the duchess of aosta helping the work of the doctors, giving orders, and providing for all. and when night fell covering so many funestous things, she got up on a horse, a simple carabineer's horse and sinking deep in rocks, and stones she reached at night somma vesuviana and returned to the royal house of capodimonte, letting nobody know what her day and her work had been. * * * i relate this fact in its high simplicity since it does not only testify to the goodness of this woman but to her incomparable moral valour, since it is not only an act of charity, but from a woman, from a lady, from a princess it is an act of heroism. and of these deeds elena of aosta the daughter of the king of france, has accomplished a great many every day in this terrible week. she has gone all about the places where it is difficult and dangerous to go, in every place worthy of a great soul and fibre like hers is; where men, and especially men, have been afraid to go, she has gone bravely several times where need was most urgent, and where storm seemed stronger, there she has gone: and every where her steps have been usefully taken, her vivid strength has been used for the good, her hands have helped and consoled, her will has accomplished miracles. and do you know in what manner? without official notices, without any pomp, without anybody knowing it, almost as if in secrecy. often people have not known her, and many don't know now that she, who has quenched the thirst and hunger of so many, she who has helped the dying in the ruins and fire, is the descendant of s. louis. she has hidden herself when meeting people who could notice her, she has always worn modest and dark clothes, and her face has been hidden by veils, and she has withdrawn when frivolous and curious people have tried to observe her doings. this noble woman has not found any rest before this terrible misfortune of ours, and her work has been a high spiritual beauty, and the modesty and silence with which she has surrounded herself has been really sublime. and i stamp here her moral image with humble admiration and proud to know she is a woman as i am; and i am happy not to have to write down only in the daily news the duchess of aosta wore on her white satin waist a magnificent emerald pin; i am happy that a feminine soul in a vigorous fibre should show the world what is the power of virtue in a woman and in a christian. and for all those whom she has conforted really, in the terrible hour not caring herself for dangers and unconforts, for all the wounded and agonizing ones, for all those who weep, and were consoled by her, i implore on her all god's blessings and may her life be sowed with all goods, and may her children be blessed through her. let the guilty ones be punished the night before easter has been full of fright and confusion for the people already prostrated by so many emotions. this ringing of telephones, this continued and sudden ringing, in the depth of night, repeated every where, in military offices, government offices, newspaper offices, this anxious running to the telephones, this news given with trembling voice, these brief dialogues sometimes impetuous, sometimes sad, have been, and still are an incubus on us all, from the general to the reporter, from the prefect to the municipal usher, from the director of a railway station to the firemen! indeed, this ringing which makes our nerves thrill in the most painful way, the exhausted nerves of all those who have been obliged to suffer for the last ten days, and think, and act, in the mean time, this terrible, continued noise has not permitted us to sleep in this night before easter. we all have been the victims of a deathly joke, invented by a man who, mad with terror, has made himself guilty of the lowest of deeds. but obeying to our rigorous duty as publishers, also in this night before easter, and in this very easter morning we have given, in a very brief and simple form, without clamour or exaggeration, without lugubrious inventions, the news which the idleness of this m. fedele had changed in a tolling of bells, and in a breath of death. it is natural that prefects, under prefects, commissaries of prefecture, should have been more than concerned, and that at head quarters they should have kept watch all night, giving orders on all the lines, awakening every body, and mobilitating every thing. has not our m. fedele spread terror every where? later on in that same easter morning, while our hearts rejoicing, especially this year when the day had brought peace and resurrection, every body was suddenly saddened by the spreading of this false news, not given by us, but thrown among us in the most emphatic and cruel way, spreading sorrow in the hardly revived spirits of the people, announcing that there were dead and wounded, even among the officers and the soldiers. oh! poor mothers of officers and soldiers near and far away, you must have been the first to get the sad news, this low lying news, and your poor heart must have been broken before you were able to know that this news it was false. * * * if an example is not given, if cowardice, lying, and foolishness are not punished, life will become even more difficult and complicated than it is for all those who have duties and responsibilities, and for the mass of citizens who need to rebuild for themselves a quiet and laborious life. we want to know who must do it, whether this m. fedele has been or has not been punished, he who has not only deserted his place, but who has upset this whole region through his fright? will he be punished? will all those functioneers, who believed this foolish news, and have called for help before knowing the truth, will they be called and invited to show some courage, some cold blood, and equilibrium? as for the agenzia stefani which has covered itself with ridicule during all the period of the eruption, telegraphing all over the world, that the vesuvian observatory had been destroyed, while the news was false, and which has been obliged to contradict the news that it had given half an hour before, it has already been justly and severely upbraided and censured by our prefect who will write to rome to the central government, that the director may be called, and an investigation made. let the culprits be punished, and let none of them have the chance to escape, or to invent any thing more. let nobody throw panic among those who have duties to fulfil in these sad and trying moments. let nobody start panic in naples, in this city which must revive and begin again its work and energy. if a whole city like ours, a whole region, a whole population, from a prince of the house of savoia to the humblest of soldiers must fall at the mercy of a frightened panic-stricken man, of an official whose business is to be forever mistaken, we would like to know if such absurd thing must be tolerated, if such thing has to continue. let all those who have any fault in the panic of last night, be punished, and let military power interfere where it must, and government one where it wants and can, provided this dangerous and annoying scandal should not be repeated. let the neapolitan public, the great punisher, act as it knows how to act when needed, and let it severely punish those newspapers that have printed false news exagrerating ruin and death. let the land be saved for the present every thing is satisfactory. the government could not, and cannot do more or better than it has done, to organise ready help through all the vast zone of the vesuvian country stricken by this dreadful conflagration. the life of one hundred and fifty thousand people running away, has been guarded and protected with energy and wisdom, and the deserted towns, those less damaged, have been in the quickest possible way set again to their own normal life. the streets quite destroyed have been rebuilt, at least in those parts where circulation is more necessary, and with the return of the many fugitives to the towns where the dreadful shower was worse, they have managed to start again a life, abnormal perhaps, but at least a life. you need only go over this long, fatiguing, hard pilgrimage, in these countries stricken by the terrible disaster, to realize the extraordinary new start to life, the work of reparation, the rebuilding of everything, where nothing more had been left. all has been made anew, from the bread for the famished, to the medical assistance to the sick, from the first work in removing cinders and lappillus, to the building of wooden barracks, from the trains already running through the high piles of rocks, to the tearing down of tumbling roofs, from the free dinners distributed all around, to the serino water brought here from naples every day. all has sprung to a new life. to say who has done all this is easy: the government has had this simple, happy idea. it has trusted two men of intelligence, two men of will, the duke of aosta and general tarditi; it has put its trust in the obedience, abnegation, heroism of the chiefs and of the soldiers; it has added to this sane, serious, and practical civil element, and has given much money, it has adhered to all requests, it has answered to all demands. ready help is active, there where life is. how long will all this last? and can it last? and must it last? the salvation of to day is done! man has saved man! those who had power, intellect, good will, ardor, enthusiasm have given it all! the history of these days will remain memorable in the pages of human help! and i would like to have the vigour and the time to write it up myself, as an homage to the ideal which binds men. but what, and who will save to-morrow man and his house, man and his descendence, man and his bread, man and his field? who and what will create a new life firm, continued, of constant evolution? one is the secret: this country must be saved. oh men! who are tenderly concerned over the despair of nearly ten thousand people, oh! men of heart and mind, give, give food to all these unfortunate beings, to these poor people who have nothing to do, to the women, to the old people, to the children! alas! you will not be able to do it always! build, rebuild roofs and hearths that they may find a shelter, but the house will perhaps be empty, and the hearth fireless. have the streets cleared free from the rocks, lapillus, and cinders which the fury of the vulcano has brought down, but these streets will be deserted and sad. reform the social life with its laws and regulations, but all that will be a dead letter. ah! all is useless if the country is not saved. the land which gives bread and fire, the land which gives life must be saved in all its region so terribly damaged. this land alone knows the secret of its resurrection. save the land, you men of good will. save it in all its modest and imposing forms: save the little orchard, and the small tract, the garden, the humble edge which closes the large field, save the land of the poor farmer, of the modest peasant, of the small land-owner, fertil or steril as it may be. modest peasant, save the land, no matter how it is, rich or poor; the land is always the land, the spring of life, the earth which is flour, vegetables, the earth which is life itself! from the miserable little grass, to the highest of trees, the earth which enriches man, warms him up, lights up his nights. the earth which gives food to the tired limbs, wood to the hearth, oil to the lamp. save this land! you cannot help these people beyond a certain length of time, your money would not be enough, your charitable impulse would not last, and of these charities people, after all, will get tired. and so it will be, for the necessity of human conscience, for the dignity of man, even if marked by misfortune. no alms any longer, but some means by which everybody may rise again, take up again his modest and laborious round of existence, support himself and his family, and close every day, with a blessing to god. some means by which he may end his mortal pilgrimage having accomplished his work among men, as a worker, and head of a family. save the earth, save the wheat and the vine, the oil and the oak, save every inch of land around the silent country homes. save the land which slopes down over the cruel and fatal mountain, just as that, farther off, which cannot fear its tragic explosion. ah, those poor lands ascending up to s. anastasia all covered and buried, but still trying to emerge, those poor country lands around beautiful somma vesuviana cut out of existence, smothered and gone! ah! that silent and deserted grave which is now the country between somma and ottaiano, dead, under half a meter of stones and cinders, everything dead, the grass, the plants, the bushes, the trees! who will forget, who will ever forget that incomparable vision of death? call men of science, those who study science to better life, and tell them to get together, to observe, to notice, to reveal to the ignorant the secret to save this dead land. call men of finances, not those who understand it as a mere dance of cyphers, but those who know what it means to life, and let them form a great project, by which the land may be saved. money will come, people are already giving it, and more will still be given, especially if people know that it is not only used for charities but for the redemption of work, not only used for provisory help, but for a larger, wiser, and more austere aid. the government will give now or later all that is necessary, and perhaps beyond what is necessary. form a great, serious practical project, based on strong views, an agrary and financial project, which may teach, guide, advise! give little or much money, as needed or where it is needed, in order that every farmer may get back his little tract of land, that every peasant may rebuild his field, and every owner may redeem his property. give your advice and take the easiest means to have it fulfilled. let money be given, not lent to he who has cleared and redeemed his field. if the money has to be lent, let it be on long time, and let the government pay a strong part of the interest on the agrary loan, just as was done at the time of the earthquake in ligury. let the cheapest and most efficacious advice be given, that every man may start with his own hands and the help of his people, to free his land from its funeral shroud, and let help be given as a prize to will, and tenacity. let it be a civil help to honest citizens, that their small destroyed fortune may be rebuilt for their children. this, at least, you must do, men of good will. let all the land around be delivered from the heavy mantle which wraps and smothers it, let it be free, and from one season to another, let the grass, plants, trees, flowers and fruits grow up again. may the waving crops spring up again, in the devastated fields, and the olive and vines grow there anew. may the almond tree bloom once more with red flowers there where the storm has passed, leaving death behind. oh men of good will if you will know how to do this, you will have saved your country, and in renewing life where death has reigned, you will have come as near to god as anybody ever did before. april , . every day has its morrow it is not certainly through cold blooded and cruel newspaper work, that i, with some strong and faithful collaborators of the "giorno" have gone in the places which have been more severely stricken by the furies of vesuvius; nor have i gone there through any stupid and vain curiosity. we had all gone before, when the tremendous eruption was at its worst and we went trembling with anxiety and we saw and felt all the horror of that storm in its terrific aspect. we returned home every evening, every night in a real convulsion of anguish. every day has its morrow, and to a period of great emotion, when all your soul rebels and rises against a misfortune which nothing can fight, another long and slow period follows, full of mortal sadness. the period of the morrow of a catastrophe when your spirit calmed down, and clear in its sadness, measures silently all the damage that people and things have suffered. for the journalistic sportsman, ottaiano, s. giuseppe, boscotrecase, torre annunziata, somma vesuviana don't hold now any more the necessary interest to suggest terrorising news, nor does the frivolous curiosity of the frivolous reader find any interest in these exausted subjects. but for me every day has its morrow, and so it is for all those who have a heart, who feel to be citizens of a great country rather than newspaper men; who feel the voice of their conscience before that of their fancy. every day has its morrow and it is this morrow that we sadly and simply have gone to seek there where the ruins of country and villages have been left. another sentiment has urged me and the other pilgrims of this humble duty, the thought that now, little by little, the violent crisis being calmed down and passed, people may forget all this great trouble! we are so willingly careless here when deep sorrow has passed, and the sun shines on human misfortunes. we forget so easily the pains and troubles of others, when the pang of their sorrow is ended. but we should not forget; we must not stop having pity, we must not stop giving our cares and help, we must continue! so we have gone every where it seemed necessary, stopping first at ottaiano, and we have seen and inquired of the people, and things have told us their secret. april , . the new pompei between two edges of lapillus which have formed on the right and left of the rails, among mountains of ashes accumulated here and there in order to free the way, that the trains might get as far as ottaiano, the little station is crowded with different and strange people. here are dark faced peasants, silently advancing from the villages where they have been sheltered, and now looking for the little home which once was theirs. civil functioneers who come here perhaps to try and, doubtless in vain, to rebuild some kind of social life among the ruins of this new pompei. small proprietors have climbed up here just through that sad curiosity some people, seem to feel who know they are ruined: rich proprietors of lands and houses, who come to calculate how much of their fortunes has been lost, and consider whether it is worth the while to fight for the future; some weeping woman of the people, a few but rare ladies who have come through a spirit of charity. many soldiers, many officers, all covered with dust, and not brilliant looking certainly, but fulfilling the most constant and patient duty, a duty always greater and more complex. here is their general in the midst of a group of persons, who draw close to him, wishing for something, (every body wishes for something), and general durelli has an answer for everyone, a brief but kind answer. he has a word for everybody, and promises only what he can keep. he is the soul, the breath, the mind, of this new pompei. i know all this, and i simply bow to him, as i don't want to make him lose any of his precious time. but later when all interrogatories, with every distinguished or obscure person, peasants, gentlemen, poor traders or proprietors of ottaiano is over, every one declares to me that in this incomparable trouble, in this ruination of the prettiest of towns, the choice of general durelli, as a reorganiser, could not be better. he occupies one of the few standing houses left inhabited by the parson, and he sleeps there a few hours, and takes his meals, but he is always on his feet, always around, plunging his high boots deep in a meter of lapillus, going to and fro, watching every thing, providing promptly to all with clear and efficacious orders. around him, groups of bare-footed women, with half naked children in their arms, push and press, while new people coming from the different main roads, arrive, urging him with demands and requests. the women, especially the poorest of them, with sad looking faces relate to him their misfortune, and general durelli always kind and patient tries to console them and give them what they ask. he begs them to be quiet and wait, hoping for better times. they draw slowly away, sitting in groups on the ground or on the accumulated ashes, forming thus a strange and never to be forgotten picture. their clothes are gray with ashes and dust, whilst their babies with smutty faces and hair, lay quietly in their arms, watching eagerly around. they wait there in silence. perhaps better hours will come. under the native roof. in the long, hard fatiguing pilgrimage where every step costs untold pain, where every look sees a precipice, a young peasant accompanies us as a guide. one reads trouble and misery in his dark eyes, his voice is low and dragging, almost complaining. are you from ottaiano, i ask him, while going up the steep road. --yes, i and my family are from that place. --did you run away from there in that terrible night? --yes, we fled just about dawn when the fall of stones was at its worst. --and how long did this last? --fully twenty four hours madam, from ten o'clock on saturday night, till ten o'clock on palm sunday. a whole day, yes, a whole day. he doesn't lie nor exaggerate. if he did, how could all this ruin be around us? --did your house fall down? i inquire. --yes, he answers sadly. there it stands on that height yonder. look at it! look at it! all i possessed is buried there! my bed, my poor furniture, all. tears gather in his eyes. at least have you saved your family? --yes, he murmurs, they are at sarno. but i have lost all. i was supporting them, and have lost my wagon and my two mules, for i was a driver. --are they buried? --the wagon can be seen under the stones; and as he speaks he seems to take heart all at once, it can be seen! perhaps i shall be able to drag it out. but the mules! the mules are dead. how shall i manage? a deep sigh heaves his broad chest. --and you have come back here, i ask him? many of you have come back? --i have come back. this is my country. i have come to try to save my wagon and those poor animals, nothing, nothing! --will you remain here? --i shall! where could i go? this is my country. i will also make my family return from sarno. if you knew how many have returned! --how many? how many? --at least three thousand. many have come back the following day. you see, we could not stay away. --and where do they live? --nearly all sleep out in the fields under straw sheds, and the others in the few houses that remain standing now. --they are building cabins, and little by little you will see every body, coming back to their own country. --was this place, fine? i ask him quite touched. --the finest of all, and our country is fine! and he utters these words enthusiastically, but again he looks down sighing, and is silent. among the ruins. of course the farther we get from the station, from municipio square, the fewer people we see, and the more we advance towards scudieri's house, ateneo chierchia, and the feudal palace of ottaiano, where the ruins take a more imposing and solemn aspect, the greater the solitude. but while we stop at every step, to look from the top of the mountains of stones and ashes, on which we climb and descend, while we look at the piled up ceilings, shutters, stones, furniture, pictures, and utensils all in demolition, now and then, we see somebody coming out of a small lane closed by a small gate. here is an old woman, she looks to be seventy years old, she is thin, wrinkled, but quite straight. i speak to her, i ask her all about that dreadful night. --i was sleeping, madam, i was sleeping. i woke up and heard screams: "the mountain, the mountain!" who could believe that a disaster was on us? what was there to be done? i turn entreating god, but i see death coming. my lady! what noise, what darkness, what flashes! the door could not be opened. i just jumped out of the window. --out of the window? at your age? --the window was low and i fell on the ashes. i began to run madly, i don't know where. i protected my head with my arm! look how wounded it is by a stone falling on me! and she shows me her fore-arm. it has a long wound, a torn place which is beginning to heal. --and where did you go? --where could i go? old as i am? in the country towards somma; there i spent the night. i said, this is the hour of my death! let your will be done my lord! --and you have come back? --i have come back. what could i do in another country? who wants an old woman? if i have to die, i want to die here. here is a man of the people coming from a street. he bends over a mattress, tucks it up and lays it on a cart which is in a corner, where he has already layed other things. --have you found your things again? i ask him. --i have found some of them, he tells me readily, with a rather excited tone. i am taking these things to sarno where my wife and children are. they have no place where to sleep. but i am coming back at once. i am a man, i can work. i am coming back day after to-morrow. i want to work here. --and what will you do? --what they'll give me to do? have you seen all those men on the square? they are not from ottaiano, they are from marigliano, pomigliano, and other countries, all people coming here to seek work. they take away the stones and cinders, and ask a great amount of money. well, this must be done by us, from ottaiano. also gratis, even if they don't give us for it but the soldiers' ranch. the country is ours, the trouble is ours, we must repair it. and he ties with a rope his few things, loads them on the cart with a firm and decided air. the babies speaking with people, i find that the most touching episodes are those concerning the babies. how heart-rending the cry and screams must have been of the parents and relatives who were trying to gather them, that they might take them away, lifting in their arms the youngest, tying to their clothes the largest, what a tearing cry must have been heard under the terrible shower of burning stones, lappillus, and ashes! many of these children, got lost through the country in that dark night, their parents, not finding them, but after three days at long distances, while for three days, they believed them dead and wept desperately over them! the boarders of ateneo chierchia ran out helping the younger ones, and carried them on their shoulders wrapped in blankets that they might not be wounded, and in these conditions they fled through the terrible night. the soldiers who had come from nola during the day gathered a number of other children, and fed them, keeping them with them till the following days, when they could be returned to their parents. as for mothers, in that terrible flight, half wild with despair, they wrapped the little ones in their dresses and shawls thus repairing them from certain death. a poor lady, who had a four months old baby, hid it under her arms, covered it with a basket, and thus carried it for eleven miles, on foot, at night, the baby however quietly sleeping under its shelter. the children of one of the teachers in ottaiano, took their father who was very ill, closed him in a kind of covered box, and carried him so, on their shoulders till caserta. the poor man naturally died there of his former trouble, but his children can say that they have saved him from dying under the stones of ottaiano. strange to say in this flight of fourteen thousand persons, not one single baby has died, and the people from ottaiano say, that this is a miracle of the madonna, a true, real miracle, and every mother clasping her child alive in her arms, has been obliged to believe in this miracle. a witness. from the ruins of his beautiful house, from the flowered terrace, covered for one meter with vulcanic stones and cinders, comes luigi scudieri, a friend of ours, a witness of the great cataclism. his gay and open expression has not changed, his family is saved, all of them, from his old parents to his children. the palaces of his noble and powerful family have tumbled down one after the other and their rich fabrics, their vast territories are now buried, for many, many years perhaps. their fortune is compromised, yet he is back here since four or five days, back in ottaiano, actively busying himself around, advising, guiding, conforting the more desolate, the desperate, helping every one, speaking to every body. of course i ask him to tell me all about the destruction of ottaiano, but notwithstanding his natural brightness, he gets confused and troubled while he speaks. --dear donna matilde, in the first hours of saturday night, i must confess, we were not much preoccupied. as you know, we have had several showers of cinders here in ottaiano, but they were short and harmless. nothing was to be feared, that evening, as i tell you, but towards mid-night the preoccupation began. the crater had fallen in, and at every breath of the vulcano, a more and more increasing fall of ashes came down, passing over the mountain of somma which protects us, and striking the whole of our place. the alarm bells began to ring. --how terrible! i exclaim. --it was well they rang the bells he says. the peasants who had all returned home for the holy week, were all fast asleep, the women at the sound of the bells, came out from their houses, running madly away, and to be sure many more would have died had the bells not rung. --how many died here in ottaiano? --about seventy, and even those might have been saved, but the night was so dark and the fall of ashes so thick. --did they all seem to lose their mind? --in the beginning no! i telegraphed to naples, and the poor telegraph operator who sent my telegram, and whose courage and devotion should be enhanced, sent these telegrams under the flashes of the mountain. twice the electric shocks threw her down. one only of my three wires, the one to the military comand reached its destination. --and your family, i ask? he seems moved and hesitating. --don't speak to me about that, he exclaims, those hours have been terrible! when i saw that we had to run away, i was obliged to nearly carry my wife who was ill and weak, on the road. quite exhausted and discouraged, she stopped to recommend me the children, asking me to let her die there in that very place. i knew nothing about my father and mother; my nephews have saved them, they had sworn to die but to save their grand parents, these brave boys. only after four days i learned that all my people were saved. --and where did they all go? --to avellino! one would hardly believe it! we reached avellino by an extra train, and there we received from all the population, and principally from good achille vetroni, a warm hospitality. you can tell it to every body in honour of vetroni and avellino. imagine that in the shops, they refused to be paid, when we went to buy shoes and boots. yes, they have really done prodigies of devotion and kindness. prodigies! tell every body what the hospitality of sarno has been for the people from ottaiano, how touching! you must also add that the first good example, came from the seminary. the good rector has promptly given up his room to m. cola, who was flying from ottaiano, quite ill. the seminarists have distributed their own clothes to the people. one can hardly realize all that has been done for the people of ottaiano everywhere they have gone, to sarno, caserta, castellammare, marigliano and nola. we shall never forget it. --and what will you do now? i ask him after a brief silence. --with what? he asks me. --with ottaiano. --rebuild it all, he answers me, quietly. --rebuild it all? --and what else can we do? we are fourteen thousand. four thousand have already returned. where do you want us to go? to turin? to milan? it is not possible. don't you see? settle in the neighbourhood? at portici! at torre annunziata? we shall always be under the vesuvius, consequently, in constant danger. better remain where we are. but the houses have tumbled down. what then? the roofs yes, but the walls are not cracked. we shall have to build the new houses with arched small iron vaults little by little! you will all help us, won't you? how can one abandon one's own country? here all of us possess much or little land, will you take from us also the hope of redeeming it for our children? what would become of us in milan, turin, even in naples? how could we hope to build up again, if we went away? but we shall need much help.... i say.... you all must unite with us. and we shall work, and we shall have to make the poor peasants work, and give them prizes for their work, and no alms nor any kind of charity. life and hope are still strong in this man who has seen death near him and his people, who has seen his village tumble down, and who is now speaking only of its resurrection. vincenza arpaia here near us a woman is speaking eagerly. she is of the peasant type, but a light of intelligence shines in her eyes, and while talking she mixes correct italian words with her dialect. she has a handkerchief tied on her head, the image of a saint hangs down on her breast, and she discusses vivaciously. i interrogate her. i know she has come back here the day after that frightful shower, and has not moved from here ever since. she counts up the houses that are still standing, she speaks of those who have returned and will return. and i learn, that she is the mid-wife of the village, vincenza arpaia. --have you your diploma, vincenza, i ask her? --of course! i received it at the university of naples, and i was appointed to this place, she exclaims with pride. not a single baby is born here, without my assistance. --all alive! --all, madam! and thanks to the lord there are no orphans. what a destruction! but now it is finished, and it will take more than a hundred years before it happens again.--she refers to the terrible fall of stones at ottaiano, in , she is rather informed, yet she preserves her popular simplicity. --and why did you return so soon, vincenza? --to attend to my work, and see after new born babies, madam. --new born babies? here? --one was born the other day, she cries gaily! a fine boy! he was born on the ruins and i shall take him to s. giovanni, to the only church still standing, and all the bells must be ringing! this woman of the people says now unconsciously a great and deep thing. a baby was born on the ruins! oh! eternal resurrection of life! oh baby! you are a symbol! life never ends! it renews itself, and it is the eternal bloom of strength and beauty. april , . ignis ardens when coming out from the station of the circumvesuviana at torre annunziata, as one goes towards the white and flowery cemetery, which was reported destroyed, but fortunately has not been touched by the fire, one suddenly sees, quite in front of the gate, at seven or eight meters from the wall on the left, a large barrier of black or dark gray stones, and pitch coloured rocks, a rocky irregular barrier closing at a certain distance the restful home of the dead, and one wonders: is this the lava? yes, that is the lava. still, asleep, and dead, it rests now under the sun, having already become a harmless thing, transformed in an arid rocky wall, in a mound of ruins, gathered there in confusion, for an unlimited extension, and going down in an easy slope, like a stair of stones. that is the lava, and who sees it for the first time, must ask himself if, in that accumulation of still things, in that ocean of fused bronze, life has existed, if that mass has not been deposited there by chance, by the untiring arm of gigantic cyclops, and not by its own strength, by its powerful and ardent life of fire. and one smiles almost incredulously, as one would, before a made up spectacle. one would like to tread over those scories, strike them with one's own stick and show them all the contempt that naturally springs from one's souls towards a stone. stone? oh no! from the cracks cutting here and there, immense columns of white smoke, tinted with yellow vapours, arise ... and if you look more intensely you perceive many, many more. it is like an immense lighted field, spread all over with smoke, similar to an early dawn in the month of november. that stone is still living. under those masses, fire is still burning. the blood of the vulcano beats yet in those stony veins. the terrible thing appears to you then, in all its majestic and frightful grandeur, always burning like the flame of the vestals. and you understand then more clearly what must have been the terrible spectacle of this slow fall of living and destructive strength advancing little by little, gaining inch by inch the fields and the houses, this invincible strength carrying flames and destruction in its breast, hearing no control, going where it pleased with the caprice of a perverted will and bringing desolation and death every where it has touched. you will well understand, what this rolling red river must have been in the fatal night, with the black sky shrouded with sun, crowned with lightnings like a revengeful divinity, this slow and voracious river, which has swallowed up half a country. you will well understand, how a picturesque little village can have been destroyed in its rich lands, in one of its fractions, in its first houses. a nice white little village, located by a black row of stone girdling it with mourning after having wrapped it with destruction, and you will then understand what must have been the panic and terror of yesterday, and what is to day the serious loss of this place which is now hardly spoken of, and which to-morrow will be probably forgotten: of boscotrecase prisoner of fire, like brunhilde of the walkyrian story and which will never be waked up again from her sleep resembling death. * * * * * if you want to go to boscotrecase, from the cemetery of torre annunziata, you may, avoiding to go down as far as scafati, ascend directly the course of the lava and coasting as i have done, three steps further you see the line of the circumvesuviana cut for several meters by the lava, which has run over the rails, falling on the ground underneath, rails being raised in that place. let us go through the fields, the front of the lava is quite wide and one must take a long turn. all around the black sleeping mass, the country has remained untouched, the vines are in bloom and young green twigs hang from them. one step from the last scories, advanced sentinels of death, little field daisies, all gold, small stars wreathing the head of the monster, are waving at the soft, light blowing breeze, while big bloody poppies like large stains of blood, fill the ground all around. half way up over the low walls of the farms, a little house appears at once before you. it is the first one which has been surrounded by the lava. in fact the walls peep out of the crags under the rocks where they are buried. all is in its place, not a shingle is missing from the roof, not a pane from the windows. only the inexorable lava closes it all around. and i have like the painful sensation of witnessing the agony of a healthy and good creature, hugged in the arms of a giant who is slowly suffocating it. still more houses are to be seen farther on; but some of them are in ruin, the lava has leant against the walls, has pressed, has broken some pillars and has opened big cracks in the walls. from a close window, i suddenly perceive, a thin line of grayish smoke. the work of the hidden fire is only beginning. the house is burning little by little. the shutters, the doors, all wooden things in contact with the lava, are beginning to burn, then it will be the turn of the beams, of the sustaining arches and the walls; every thing will be consumed to ashes, and only some ruins will remain. how long will it take? who knows? the work of fire is silent and tenacious like a human vengeance. after an hour's march we abandon the poor, deserted dwellings, irremessibly condemned, vowed to death, yonder in the great sea of lava, and we get back in the main road, full of dust, leading to boscotrecase. at boscotrecase entering the little town one receives the impression that nothing abnormal has happened there. truly few people are circulating in the streets, the shops are open, women are standing at the doors of their houses, sewing, chattering, while streams of children play in the sun. we go about the street which bears the name of cardinal prisco. it is extremely quiet, almost asleep in the meridian hours and we get to the oratorio. at the end of the road, between two houses we are surprised to see a kind of fence made of wood and beams, in the shape of a cross. is it a barricade? no it is the barrier! on the other side there is lava. there it is, in fact, the black enemy, there in the village, running between two wings of houses, sneaking in a little lane, there it lies dead without the strength to go any farther. and this is only a little stream, but at a short distance, what vast and imposing river. all the oratorio square is invaded and submerged. it is like a row of stormy waves, petrified as by a strange prodigy, standing erect among the edifices. here, and there on the crest, a soldier, a sentinel appears. the image of s. anna, the patron of the place has been taken elsewhere to a house on the ground floor, in oratorio street, and the opened windows look like empty, while the bells hang in a silence which will have no end. i turn to another side, through a path the soldiers are opening. i pass between two lines of infantry diggers, small creatures curved on the stones, in an audacious and patient work. they look and smile under the shade of their straw hats, and start again to work. how many days have they been there? how long will they still remain? who knows? they themselves don't know it. and they bend on the fatiguing and tenacious work like brave boys asking nothing for themselves, and they give all their fatigue, strength, youth, happy in the hard striking of their picks, in the hard digging of their hoe, singing softly the ritornelli, of their native songs as if they were in their native villages beyond the mountains working in the corn fields or among the vines. the lava in the tour this large tract of lava which thanks to the works of repair can be crossed in a carriage, has cut the town in two. from this point the streets begin again to be quiet and the houses to be inhabited, normal life seems to reign every where. here is citarella street, here is giordano street with its green orchards, and the dogs sleeping on the thresholds of the houses, and the old people bathing in the sun. but suddenly another branch of lava is standing in front of you, it is the one that has invaded the other side of the oratorio cutting the communication with tre case. it has sneaked in the town, getting in the lanes, through the orchards, assaulting the houses from behind, reversing itself from the ground-floors against which the wave has struck. i see a house completely surrounded and taken by the lava, quite in front of pagliarella street, it is the house of a certain giuseppe principini. the first floor has fallen in, the lava has penetrated through a window at the shoulders of the house, it has invaded the first room, it has filled the second, it has made the floor fall in, and has then reversed itself down in a cascade which has remained petrified, looking almost like a fantastic bridge of black scories, gracefully modelled on bronze. another little room near is full of lava up to the windows. among the black masses, a little twisted serpent peeps out. it is all that remains of a bed stead. the wall near the house is dry, the water has evaporated, before the fire touched it. the sea of lava on the three first high steps of the branch of lava which runs to tre case, i met engineer pasquale acunzo, a technical engineer. he has been at his place untiringly, from the first moment of the danger, directing the work of dikes when the lava was coming down, and now he directs the construction of the street which must unite boscotrecase to its nearest centers. all our communications with torre annunziata and tre case are cut off; it is the death of the country. the only road that remains open to us, is the long and rough one to scafati. engineer acunzo accompanies us up the steep way, on the lava. m. luigi casella, worthy mayor of boscotrecase, joins us. he has been one of the bravest and busiest in this sad fight, and has given himself entirely to the saving of his country, uncaring of himself, of his goods, of his houses which he has lost, all buried under the lava. the front part of the lava is getting higher and higher. from its brief starting point, it touches already the first floor of a house. we walk near the balconies, with their banisters split, all bent outside as if a gigantic hand had twisted them. working men belonging to the genio civile, are working hard to carry away all that can be saved, to demolish what is in danger, and to prop up the rest. gushes of suffocating smoke, come out from the cracks. here also the silent work of fire has begun. all around the temperature is very high: it feels as if one was near the mouth of an oven. all at once, here we are on the large spreaded lavas, opening wide and free as far as the skirts of the mountain. it is a sea, rough and upset, a race of points, pics, crests, a chain of small hills as far as the eye can reach. the sun snatches from that sea reflections of bronze which become more and more opaque with the drawing back of the wave up the mountain. further it blends itself in a grayish and uniform stratus. here and there dense smoke comes out from the cracks it is like the burning of copious incense to an unknown god, a god of terror and destruction. now and then small houses are seen. here is a half tumbled down palace, the panes of the windows are all pierced with holes it is the home of m. bifulco. here is a part of a ruined wall, it is the little church that bernardo tanucci has built in remembrance of another eruption. and other houses, and other ruins, and everything buried under the great infinite sea, scattered everything. but as a contrast, if you look down, the slope at the left, there beyond the stretch of green orchards, behind the white girdles of the houses, far, away, at the end there is the sea ample and serene, bathed in a soft, sapphire colour just as in an april day. the sea shining as a hope, in front of the ruins of a country, which has no other confort but to hope. the very serious damages it is urgent to provide. the damages of boscotrecase are very grave and serious. it is calculated, that two hundred and fifty houses have been surrounded by lava or destroyed, almost the fourth part of the town, and with them about a thousand acres of land are destroyed, each acre here is worth two thousand francs. the lava has thus swallowed two million francs. and the houses are worth perhaps another million, perhaps more. and there is a suburb tre case which has remained cut out from all communications, because the lava surrounds it on every side. what is done for this country? our courageous soldiers are working, it is true, m. acunzo's working men are also desperately working, and the mayor, good m. casella does what he can. but it is necessary to do much and to give much. this poor devastated and blocated country must spring up to life again, measures must be taken by those that can and must. the population is all back, and those who have found the little houses untouched by the fire, but emptied by thieves, have, gone back to it, providing at best to all that had been stolen, and those who have not found it any longer, have arranged themselves the best they could, resigned, because they hope. and the hopeful words on everybody's lips, the trusting words repeated by all those who accompanied, me especially by m. acunzo and mayor casella, have greatly moved me for i felt that by encouraging them, i was only an accomplice in a pitiful lie. our return has been discouraging, and while our little tram was rapidly going down through the fields, i was looking at the great and silent murderer still proudly showing its top all covered with ashes, almost as an espiation. open roads it is possible now for every body to go everywhere, in the places where the conflagration has passed in all its most varied and terrible forms. the circumvesuviana and all those great men who are its very soul, strength, and organism accomplish real miracles, from giuseppe sirignano, to emmanuele rocco and its director ingaranni, all deserve the deepest sympathy and gratitude. it is owing to them and their abnegation that the circumvesuviana has been able to resume its work, rendering thus both a great service to the work of help and to the help organizers. but for them no one could have got to torre annunziata, boscotrecase, ottaiano, san giuseppe, or somma vesuviana, for the lava, the burning stones, lapillus and ashes have passed every where. now one may go over there, not only by rail but to certain points by auto, and to some others by carriages. the roads are open. they certainly are not pleasure or excursion roads, you do not go there as you would go to a pic-nic, but whoever has a charitable heart, may go now and see, this most terrible catastrophe of the vesuvian comunes. it is a pilgrimage of piety which certainly will bear its good fruits. so many people need to see in order to believe, so many people need to let the truth of human troubles descend from their eyes into their hearts. the roads are opened for trains, automobiles, carriages, even bicycles, and for those who have to go on foot, many roads are quite practicable. let every person of good will know it. the misery of the people there is great, help must be great. the crowd, the crowd must go with the lire, of the modest giver and the of the richer one. the roads are open, the pilgrimage can be made, without spending much, without asking too much, without taking too much trouble, without losing much time. and those who go will realize how great this calamity is, and how great the remedy must be. april th . the way to go well, my dear readers, you who are living in naples, you who will come to naples to morrow or later, you can now safely go on the roads damaged by the eruption, by any means of transportation you like. the best, of course, the one i would suggest as the best, being more comfortable, very rapid and suiting all pockets is the quite popular railway of the circumvesuviana, that same road, which has saved men and things, which is really the best help for the reorganization of life, up there. it will carry you easily to see the lava at torre annunziata, and farther still if you like to see the new pompei, that is, ottaiano and s. giuseppe of ottaiano. reader, if you are a woman going, don't wear nice clothes, because there is always some wind raising the ashes and your clothes would be ruined; put on a simple woollen dress, a gown, a shirt waist and a simple figaro, so that you may take it off if it gets too hot. put on a small hat, if you go there by train, and a cap if you go by automobile, and cover up either of them with a white, gray, or pale lilac veil hiding thus your face, your hair, and your neck. if you possess a big white chiffon scarf, wrap up your hat and face in it and tie it under your chin. if you have weak eyes put on a myrtle green or golden brown veil but large and closed. wear a good pair of black boots, with low heels and comfortable. a parasol is useless: with your large veil, you are protected from the sun, whilst a parasol would be an encumbrance. a good stick might not be useless. then with your short skirt which enable you to walk quickly and well protected from the gushes of ashes raised by the wind, you may go any where you like even on the lava of boscotrecase, on the mountains of lappillus in ottaiano, on the observatory and the crater, if you have the strength and courage to do it. you may see all, and know all, and you will return home with a world of new and deep impressions. if you want to breakfast, you will find what is necessary anywhere even in ottaiano or boscotrecase, but don't forget to carry within you a tender heart, and any thing you can possibly gather to give to women and to babies. anything, an apron or an handkerchief to one single woman, or a small shirt or a little dress to one single child. don't forget this and god will bless your steps. april th . a prince i stop a moment to look at him! i had always seen him silent and thoughtful through the fields, when the black lava smoked furiously covered by the sepulchral sheet of ashes, in those towns destroyed by the stones, but in that day he was thoughtful and sad. on his brow was written a silent sorrow. we were in a deserted spot, outside somma vesuviana in the saddest hour of that sad monday, which will never leave anybody's memory. we saw him going away, without daring to inquire from anybody, what could be the reason of his depression. but two hours later we found out that he had been witnessing at s. giuseppe the drawing out of the bodies from the ruins of the church, where more than two hundred persons had been buried. till then the duke had only witnessed the destruction of the houses and lands where human life had been spared. but there he had seen death, the formidable host, and all the horror of it, and all his sorrow as a man and as a christian rose from his kind tender heart and showed in his brow. * * * * * no commemorative inscription, nor the plause of assemblies can be an adequate recompense to the work of this prince. these forms are all academical and nearly bureaucratic. let them go with the banalities which are still smotering modern society, it is difficult to escape such conventionalism. for us that is not enough. we think with terror of what would have become of one hundred and fifty thousand people, running away under a rain of fire, if the duke of aosta had not been there! we tremble at the thought of what would have happened if he had not thought of all, ordered all, provided to all. what is an inscription, a vote, an applause before this real great soul, where one finds harmoniously blended, the virtues of the soldier and of the christian? where a prince has all the virtues of a true citizen, where heroism is united to simplicity and where the ardour of good is ineffable? let your memorial stone raise a word of admiration, but all this will never tell how high, pure, efficacious has been the energetic enthusiasm of emmanuele filiberto in order to save a whole population. let him continue. don't you see? all his spirit and will are now ready to every thing. he wants to get to the point, he wants not only to help but he is already looking forward to the building of the places. he wants to save the lands, the fields, he wants work to start over again, he wants every man to build again his roof, his bread. let him continue. to morrow every body will forget perhaps the terrible catastrophe. he does not forget, he will not let the others forget, he will surmount every obstacle with his moral strength, he will accomplish a longer, deeper, and more lasting work, he will rebuild a civil life there where it has been destroyed. we, profoundly moved, and full of admiration for all that this prince is doing, we mark this first period of his great work, where he has saved by his example and his strength of action this country, and we see him going ahead fortified by his faith, towards the greatest of works, and our eyes are wandering, and our soul believes in him. april . index quia pulvis es _pag._ towards the city of fire " a prayer " in the dead towns " in the country of death " the heroes " let us speak to the people " to the women of naples " easter of resurrection " four-thousand little boxes " a woman " let the guilty ones be punished " let the land be saved " every day has its morrow " the new pompei " ignis ardens " open roads " the way to go " a prince " transcriber's notes: --obvious print and punctuation errors were corrected. --the exact name of the town is "ottaviano"; since "ottaiano" is constantly used in the book, it has been left as it is. on the internet archive. all derived products are placed in the public domain. transcriber note text emphasis is denoted as _italics_ and =bold=. whole and fractional parts of numbers as - / . thoughts on a pebble. [illustration] reeve, benham, and reeve, printers and publishers of scientific works, king william street, strand. [illustration: gideon algernon mantell, l.l.d. f.r.s _vice-president of the geological society &c. &c._] thoughts on a pebble, or, a first lesson in geology. by the author of "the wonders of geology." [illustration: _the nautilus and the ammonite._ _vide_, p. .] "there is no picking up a pebble by the brook-side, without finding all nature in connexion with it." _contemplations of nature._ eighth edition; with thirty-two illustrations. london: reeve, benham, and reeve, king william street, strand. . to my son, =reginald nebille mantell, c.e.,= these "thoughts on a pebble" are most affectionately inscribed. london, , chester square, pimlico. . "every grain of sand is an immensity--every leaf a world--every insect an assemblage of incomprehensible effects in which reflection is lost." lavater. "to the natural philosopher there is no natural object that is unimportant or trifling. from the least of nature's works he may learn the greatest lessons. the fall of an apple to the ground may raise his thoughts to the laws which govern the revolutions of the planets in their orbits; or the situation of a _pebble_ may afford him evidence of the state of the globe he inhabits, myriads of ages before his species became its denizens." sir j. f. w. herschel. to the reader. deeply impressed with the conviction that it is of the highest importance the young and inquiring mind should have a correct idea of natural phenomena--that it should not be left to its own unaided efforts to unravel the mysteries of the beautiful world in which this first state of being is destined to be passed--or have its curiosity stifled or misled by unsatisfactory or erroneous conjectures--i have endeavoured in this little work to explain in a simple and attractive guise, some of the grand truths relating to the ancient physical history of our planet, which modern geology has established. the favourable reception of these desultory "_thoughts_" which were originally penned for the amusement and instruction of an intelligent boy, is a gratifying proof that the attempt has not been unsuccessful; and i would fain indulge the hope, that this "_first lesson in geology_" may still be productive of good, by exciting in some youthful minds a desire for the acquisition of natural knowledge; and inculcating the important truth, that he who formed the universe has created nothing in vain; that his works all harmonize to blessings unbounded by the mightiest or most minute of his creatures; and that the more our knowledge is increased, and our powers of observation are enlarged, the more exalted will be our conception of his wondrous works. chester square, pimlico. contents. page. thoughts on a pebble: part i. more thoughts on a pebble: part ii. "the nautilus and the ammonite" supplementary notes note i. _shells in chalk_ ---- ii. _wood in flint_ ---- iii. _whitby ammonites_ ---- iv. _fossil nautili_ ---- v. _brighton cliffs_ ---- vi. _rotaliæ in chalk and flint_ ---- vii. _isle of wight pebbles_ ---- viii. _zoophytes of the chalk_ ---- ix. _minute corals from the chalk_ ---- x. _infusorial earths_ lignographs. page. . vignette of title-page. . fossil turban-echinus (_cidaris_), with spines. . bivalve with spines (_plagiostoma spinosum_) in chalk; from lewes. . teeth of several species of the shark tribe, in chalk; from lewes. . chalk-dust highly magnified, consisting of minute shells. . shells (_rotaliæ_) from the chalk, highly magnified. . ammonite (_a. communis_) from the lias, at whitby. . nautilus (_n. elegans_) from the chalk-marl, lewes. . view of the cliffs east of brighton. . fossil animalcules (_xanthidia_) in flint. . _xanthidium palmatum_, in flint. . rotalia in flint. . minute scales of fishes in flint. . choanites from the chalk; near lewes. . a branch of fossil coral attached to the pebble . coral-polype in flint. . minute corals from chalk. . fossil cases or shields of animalcules from richmond, virginia; highly magnified. . several species of lamp-shells (_terebratulæ_) from the chalk, near brighton. . silicified oyster from the chalk. . coniferous wood in flint, from lewes priory. . several species of ammonite. . the body of a recent microscopic animalcule (_nonionina_), the shell having been removed by immersion in acid. . a branch of sponge in flint; a minute coral from chalk; and a section of a pebble enclosing a zoophyte (_siphonia morrisiana_). . flints deriving their shapes from zoophytes (_ventriculites_). . ventriculites in chalk; from lewes. . portions of three kinds of recent corals. lithographs. page. plate i. a rolled flint pebble, having a choanite as a nucleus, and the remains of an echinus and spine, shell, and coral, apparent on the surface. plate ii. a longitudinal section of the pebble, showing the structure of the enclosed _choanite_. plate iii. a polished section of an ammonite, having the septa or chambers filled with variously coloured spar, &c. plate iv. polished sections of two pebbles from the isle of wight; in the upper specimen, the transition from opaque flint to cloudy chalcedony and transparent quartz crystals, is beautifully shown; the lower specimen is richly tinted; the dark appearance is derived from manganese. [illustration: _plate i._ "the pebble" _page _] thoughts on a pebble. "honoured, therefore, be thou, thou small pebble, lying in the lane; and whenever any one looks at thee, may he think of the beautiful and noble world he lives in, and all of which it is capable." leigh hunt's _london journal_, p. . part i. well might our immortal shakspeare talk of "_sermons in stones_;" and lavater exclaim, that "_every grain of sand is an immensity_" and the author of 'contemplations of nature' remark, that "_there is no picking up a pebble by the brook-side without finding all nature in connexion with it._" i shall confine my remarks to a _flint_ pebble, as being the kind of stone familiar to every one. the pebble i hold in my hand was picked up in the bed of the torrent which is dashing down the side of yonder hill, and winding its way through that beautiful valley, and over those huge rocks and mounds confus'dly hurl'd. the fragments of an earlier world, which partially filling up the chasm, and obstructing the course of the rushing waters, give rise to those gentle murmurings that are so inexpressibly soothing and delightful to the soul. [sidenote: origin of the pebble.] upon examining this stone i discover that it is but the fragment of a much larger mass, and has evidently been transported from a distance, for its surface is smooth and rounded, the angles having been worn away by friction against other pebbles, produced by the agency of running water. i trace the stream to its source, half way up the hill, and find that it gushes out from a bed of gravel lying on a stratum of clay, which forms the eminence where i am standing, and is nearly feet above the level of the british channel. from this accumulation of water-worn materials the pebble must have been removed by the torrent, and carried down to the spot where it first attracted our notice; but we are still very far from having ascertained its origin. the bed of stones on the summit of this hill is clearly but a heap of transported gravel--an ancient sea-beach or shingle--formed of chalk-flints, that at some remote period were detached from their parent rock, and broken, rolled, and thrown together, by the action of the waves. we are certain of this because we know that flints cannot grow;[a] that they were originally formed in the hollows or fissures of other stones; and upon inspecting the pebble more attentively, we perceive, not only that such was the case, but also that it has been moulded in _chalk_, for it contains the remains of certain species of extinct shells and corals, which are found exclusively in that rock. here then a remarkable phenomenon presents itself for our consideration; this flint, now so hard and unyielding, must once have been in a soft or fluid state, for the delicate markings of the case and spine of an _echinus_, or sea-urchin, are deeply impressed on its surface;[b] and a fragile shell with its spines, is partially imbedded in its substance.[c] nay more, upon breaking off one end of the pebble,[d] we find that a sponge, or some analogous marine zoophyte, is entirely enveloped by the flint; and also that there are here and there portions of minute corals, and scales of fishes. what a "_medal of creation_" is here--what a page of nature's volume to interpret--what interesting reflections crowd upon the mind! [a] "_flints cannot grow._"--here i would digress for a moment to notice an opinion so generally prevalent, that perhaps some of my young readers will not be prepared at once to answer the question--_do stones grow?_ the farmer who annually ploughs the same land, and observes a fresh crop of stones every season, will probably reply in the affirmative; and the general observer who has for successive years noticed his gardens and plantations strewn with stones, notwithstanding their frequent removal, may possibly entertain the same opinion; but a little reflection will show that stones cannot be said to grow or increase, in the proper acceptation of the term. animals and plants grow, because they are provided with vessels and organs by winch they are capable of taking up particles of matter and converting them into their own substance; but an inorganic body can only increase in bulk by the addition of some extraneous material; hence stones may become incrusted, or they may be cemented together and form a solid conglomerate, but they possess no inherent power by which they can increase either in size or number--_they cannot grow_. [b] plate i, _a_. [c] plate i, _b_. [d] plate i, _c_. [sidenote: fossil echinus with spines.] [illustration: lign. :--fossil turban echinus, with its spines; in limestone. (see '_medals of creation_', p. .)] [sidenote: fossil shells in chalk.] [illustration: lign. :--shell with spines, imbedded in chalk; from lewes. (see '_medals of creation_,' p. .)] to avoid confusion, we will reverse the order of our inquiry, and first contemplate the formation of the flint in its native rock. the chalk, that beautiful white stone, which (as an american friend, who saw it for the first time, observed), is so like an artificial production, abounds in marine shells and corals, and in the remains of fishes, crabs, lobsters, and reptiles, all of which differ essentially from living species; although a few of the corals and shells resemble, in some particulars, certain kinds that inhabit the seas of hot climates. these remains are found in so perfect a state--the shells with all their spines and delicate processes (_lign. _), and the fishes with their teeth (_lign, _), scales, and fins, entire--that no doubt can be entertained of the animals having been surrounded by the chalk while living in their native sea, and that many of them were entombed in their stony sepulchres suddenly, when the rock was in the state of mud, or like liquid plaster of paris.[e] [e] see note i. _shells in the chalk._ [illustration: lign. :--fossil teeth of fishes of the shark family, in chalk; from lewes. (see '_medals of creation_.' p. .)] [sidenote: shells and fishes in chalk.] but besides the fossils which are obvious to the unassisted eye, the chalk teems with myriads of minute forms that may readily be detected with a lens of moderate power; and even when these have been extracted, the residue, which appears to be merely white calcareous earth, is found, when examined under the microscope, to consist almost wholly of bodies yet more infinitesimal--of perfect shells and corals, so minute, that a cubic inch of chalk may contain upwards of a million of these organic remains (see _lign. _)! [illustration: lign. :--a few grains of chalk-dust highly magnified, and shown to consist of shells, &c. _a, a_, shells called rotalia. _b_, ------------- textularia. (see '_medals of creation_,' p. .) ] the chalk is stratified--that is, divided into _strata_ or layers--as if a certain quantity of mud had sunk to the bottom of the sea, and enveloped the shells, corals, &c., which fell in its way, and had become somewhat solid before another layer was deposited upon it. [sidenote: flint nodules and veins.] the mineral substance termed _silex_ or _flint_, is variously distributed in the chalk. it most commonly occurs in the state of nodules of an irregular or spheroidal, globular figure, which are arranged in rows parallel and alternating with, the cretaceous strata; it is likewise disposed in continuous thin layers, which are spread over considerable areas; and it often forms horizontal, vertical, and oblique veins, that fill up the fissures and interstices of the chalk. the siliceous nodules frequently enclose corals, shells, sponges, and other organic remains, as in the pebble before us; and in many instances these fossils are found partly imbedded in the chalk and partly invested with flint. but though flints contain in abundance relics of the same species of marine animals as the chalk, they are not like that rock composed of an aggregation of fossil remains; on the contrary, the siliceous earth, which is their constituent substance, was evidently once in a state of complete solution in water, and precipitated into the chalk before the latter was consolidated, the organic bodies serving as nuclei or centres around which the silex concreted; for the deposition of the flint, like that of the chalk, appears to have taken place periodically.[f] [f] note ii. _wood in flint._ [illustration: lign. :--minute fossil shells from flint and chalk, very highly magnified, and seen by transmitted light. , , , , rotaliæ; , portion of a nautilus; , rotalia composed of flint. (see '_medals of creation_,' p. .) ] [sidenote: animalcules in chalk.] the composition of the chalk, and the prevalence throughout that rock of the relics of animals that can only live in salt-water, prove incontestably that the chalk and flint were deposited in the sea; and that our beautiful south downs, now so smooth and verdant, and supporting thousands of flocks and herds, and the rich plains and fertile valleys spread around their flanks, were once the bed of an ocean. it is also evident not only that such must have been the case, but also that the chalk was deposited in the basin of a very _deep_ sea--in the profound abyss of an ocean as vast as the atlantic. [sidenote: ammonites and nautili.] from the absence of gravel, shingle, and sea-beach, it is certain that the white chalk-strata were formed at a great distance from sea-shores and cliffs; and this inference is confirmed by the swarms of shells termed _ammonites_ and _nautili_, which we know from their peculiar structure were, like the recent pearly nautilus, inhabitants of deep waters only. for these are chambered shells; that is, are divided internally by thin transverse shelly septa or plates, into numerous cells; the body of the animal occupied only the outer compartment, but was connected with the entire series of chambers by a tube or siphuncle, which passed through each partition. this mechanism constituted an apparatus which contributed to the buoyancy of these animals when afloat on the waves; for the ammonites and nautili were able to swim on the surface, or sink to the depths of the ocean at pleasure. the fragile nautilus that steers his prow, the sea-born sailor of his shell canoe, the ocean mab, the fairy of the sea, o'er the blue waves at will to roam is free. he, when the lightning-winged tornadoes sweep the surf, is safe, his home is in the deep; and triumphs o'er the armadas of mankind, which shake the world, yet crumble in the wind. byron, _the island_. [sidenote: whitby snake-stones.] [illustration: lign. :--ammonite from whitby.] the ammonites, so called from the supposed resemblance of their shells to the fabled horn of jupiter ammon, are only known in a fossil state; but they must have swarmed in the ancient seas, for several hundred species have been discovered in the chalk and antecedent strata, though none have been found in any deposits of more recent formation; at the termination of the chalk epoch the whole race, therefore, appears to have perished. the ammonites are commonly termed _snake-stones_, from the origin ascribed to them by local legends; those of whitby are well known (see _lign. _).[g] [g] note iii. _whitby ammonites._ thus whitby's nuns exulting told-- how that of thousand snakes, each one was changed into a coil of stone, when holy hilda prayed: themselves, within their sacred bound, their stony folds had often found. scott's _marmion_. [illustration: lign. :--nautilus from the chalk, near lewes, (one-eighth the natural size.)] the nautili were the contemporaries of the ammonites, and many kinds are found associated with those shells, in strata far more ancient than the chalk; and several species of both genera, as we have previously shown, were inhabitants of the cretaceous ocean. when the ammonites became extinct, the nautili continued to flourish, and numerous examples occur in the strata that were deposited during the vast period which intervened between the close of the chalk formation, and the dawn of the existing condition of the earth's surface. at the present time two or three kinds only are known in a living state, and these are restricted to the seas of tropical climes, and so seldom approach the shores, that but few specimens of the animals that inhabit the shells have been obtained. the nautilus, therefore, is one of those types of animal organization that have survived all the physical revolutions to which the surface of the earth was subjected during the innumerable ages that preceded the creation of the human race.[h] this remarkable fact is portrayed with much force and beauty by mrs. howitt, in the following stanzas: [h] note iv. _fossil nautili._ to the nautilus. thou didst laugh at sun and breeze in the new created seas; thou wast with the reptile broods in the old sea solitudes, sailing in the new-made light, with the curled-up ammonite. thou surviv'dst the awful shock, which turn'd the ocean-bed to rock; and chang'd its myriad living swarms to the marble's veined forms. thou wert there, thy little boat, airy voyager! kept afloat, o'er the waters wild and dismal, o'er the yawning gulfs abysmal; amid wreck and overturning, rock-imbedding, heaving, burning, mid the tumult and the stir, thou, most ancient mariner! in that pearly boat of thine, sail'dst upon the troubled brine. [sidenote: the sea-shore.] we have thus acquired satisfactory proof that the flint of which our pebble is composed, was once fluid in an ocean teeming with beings, of genera and species unknown in a living state, and that it consolidated and became imbedded in the chalk, which was then being deposited at the bottom of the sea; hence the shells, corals, and other organic remains, which we now find attached to its surface, and enclosed in its substance. thus much for the origin of the pebble; let us next inquire by what means it was dislodged from its rocky sepulchre, cast up from the depths of the ocean, and transported to the summit of the hill whence it was dislodged by yonder torrent. if we stroll along the sea-shore, and observe the changes which are there going on, we shall obtain an answer to these questions; for there is a _language_ by the lonely shore-- there is society where none intrudes, by the deep sea, and music in its roar! byron. the incessant dashing of the waves against the base of the chalk-cliffs, undermines the strata, and huge masses of rock are constantly giving way and falling into the waters. the chalk then becomes softened and disintegrated, and is quickly reduced to the state of mud, and transported to the tranquil depths of the ocean, where it subsides and forms new deposits; but the flints thus detached, are broken and rolled by attrition into the state of boulders, pebbles, and gravel, and ultimately of sand. [illustration: lign. :--view of brighton cliffs; looking eastward from kemp town.[i] _a. cliff's composed of chalk rubble._ _b. ancient elevated sea-beach._ _c. chalk forming the base of the cliffs._ ] [i] note v. _brighton cliffs._ [sidenote: brighton cliffs.] now we must bear in mind, that had the chalk remained at the bottom of the deep sea in which it was originally deposited, it would not have been exposed to these destructive operations. it is therefore manifest, that at some very distant period of the earth's physical history, the bed of the chalk-ocean was broken up, extensive areas were protruded above the waters, lines of sea-cliffs were formed, and boulders, sand, and shingle accumulated at their base. subsequent elevations of the land took place, and finally, the sea-beach was raised to its present situation, which is several hundred feet above the level of the sea! every part of the earth's surface presents unequivocal proofs that the elevation of the bed of the ocean in some places, and the subsidence of the dry land in others, have been, and are still, going on; and that, in truth, the continual changes in the relative position of the land and water, are the effects of laws which the divine author of the universe has impressed on matter, and thus rendered it capable of perpetual renovation:-- art, empire, earth itself, to change are doomed; earthquakes have raised to heaven the humble vale, and gulfs the mountain's mighty mass entombed, and where the atlantic rolls wide continents have bloomed. beattie. [sidenote: immutability of the sea.] our noble poet, lord byron, in his sublime apostrophe to the sea, has most eloquently enunciated the startling fact revealed by modern geological researches,--namely, that if the character of immutability be attributable to anything on the surface of our planet, it is to the ocean and not to the land!-- roll on, thou deep and dark blue ocean--roll! ten thousand fleets sweep over thee in vain; man marks the earth with ruin--his controul stops with the shore:--upon the watery plain the wrecks are all thy deed, nor doth remain a shadow of man's ravage, save his own. when, for a moment, like a drop of rain. he sinks into thy depths with bubbling groan, without a grave, unknell'd, uncoffin'd, and unknown! thy shores are empires, changed in all save thee,-- assyria, greece, rome, carthage, what are they? thy waters wasted them while they were free, and many a tyrant since; their shores obey the stranger, slave, or savage,--their decay has dried up realms to deserts:--not so thou, unchangeable, save to thy wild waves' play-- _time writes no wrinkle on thine azure brow:_ _such as creation's dawn beheld, thou rollest now!_ thou glorious mirror, where the almighty's form glasses itself in tempests; in all time, calm or convulsed--in breeze, or gale, or storm, icing the pole, or in the torrid clime dark-heaving, boundless, endless, and sublime-- the image of eternity--the throne of the invisible; even from out thy slime the monsters of the deep are made; each zone obeys thee: thou goest forth, dread, fathomless, alone! childe harold. _canto iv._ [sidenote: apostrophe to the ocean.] i will conclude this "first lesson" with the following beautiful remark of an eminent living philosopher:[j]--"to discover order and intelligence, in scenes of apparent wildness and confusion, is the pleasing task of the geological inquirer; who recognises, in the changes which are continually taking place on the surface of the globe, a series of necessary operations, by which the harmony, beauty, and integrity of the universe are maintained and perpetuated; and which must be regarded, not as symptoms of frailty or decay, but as wise provisions of the supreme cause, to ensure that circle of changes, so essential to animal and vegetable existence." [j] dr. paris. [illustration] more thoughts on a pebble. "not a mote in the beam, not an herb on the mountain, not a pebble on the shore, not a seed far-blown into the wilderness, but contributes to the lore that seeks in all the true principle of life--the beautiful--the joyous--the immortal." sir e. bulwer lytton's _zanoni_. part ii. more thoughts on a pebble!--is not the subject exhausted? have not all the hieroglyphics impressed on the flint been interpreted?--can science, like the fabled wand of the magician, call forth from the stone and from the rock their hidden lore, and reveal the secrets they have so long enshrined?--gentle reader! but one page of the eventful history of the pebble has been deciphered; i proceed to transcribe this natural record of the past, explain its mysterious characters, and present to thy notice the marvels they disclose. our previous examination of the specimen showed that the flint had once been in a fluid state, and had consolidated in a sea inhabited by shells, echini, fishes, corals, sponges, and other zoophytes; and the appearance of the fractured end (_plate i, c_), indicated that some organic body had formed the nucleus of the pebble, and that traces of the structure of the original still remained. to ascertain if this inference is correct, it will be necessary to divide the stone in a longitudinal direction--but i will first strike off a small fragment, and examine it by the aid of a microscope. [sidenote: fossil animalcules.] [illustration: lign. :--fossil animalcules (_xanthidia_) in flint.] by a sharp blow of a hammer, a very thin and minute portion of the flint has been detached (see _lign. , fig. _); it is translucent, and when held between the eye and a strong light, appears like a slice of horn; and a few extremely minute specks may with difficulty be detected. under the microscope, five of these almost invisible points are well defined, and present a radiated appearance (see _fig. _); but i will substitute a higher power, and lo! they are seen to be distinct globular or spherical bodies beset with spines (_fig. _); and with a still more powerful lens, one which magnifies many hundred times, their nature is completely displayed. the whole five possess this general character--a central globular case or shell, from which radiate tubes or hollow spines, that terminate in fringed or divided extremities (_figs. , , _); but these bodies differ from each other in the relative proportions of the shell and spines, and in the number, shape, and length of the tubular appendages. the group, in short, is separable into three distinct species, of the same kind of fossil remains; and several other varieties occur in the chalk and flint. . [sidenote: xanthidia in flint.] [illustration: lign. :--_xanthidium palmatum_ in flint: highly magnified.] but what are these bodies?--they are the durable cases of animalcules, many species of which swarm in our seas, and are so minute, that thousands may be contained in a drop of water! in a living state, the case is flexible and filled with a granular jelly, which is the soft body of the animalcule, and the tubes and the outer surface are invested with a similar substance. after death the soft parts dissolve; but the case and its spines often remain unchanged. in another magnified portion of the pebble, a specimen of the microscopic discoidal shells which we have already seen compose the greater part of the white chalk (_lign. _, p. ), is beautifully displayed when viewed by transmitted light, under a highly magnifying power (_lign. _).[k] our investigation has thus shown, that a great part of the pebble is actually composed of the aggregated fossil remains of animalcules, so minute as to elude our unassisted vision, but which the magic power of the microscope reveals to us, preserved, like flies in amber, in all their original sharpness of outline and delicacy of structure. [k] note vi. _rotaliæ in chalk and flint._ [sidenote: rotalia in flint.] [illustration: lign. :--rotalia in flint: highly magnified.] on another fragment of this stone two glittering specks, not larger than a pin's head, are discernible (_lign. _): these with a magnifier of moderate power, are seen at a glance to be scales of fishes. but they differ from each other; both have the surface smooth, and without enamel: in the one the margin or edge is simple (_fig. _); in the other, it is divided like the teeth of a comb (_fig. _);--trifling as this difference may appear, it is sufficient to enable the naturalist to determine that the fishes which furnished these scales belonged to two distinct orders, of which the salmon and the mullet are living examples. [illustration: lign. :--scales of fishes in flint. fig. .--a fragment of the pebble with the scales of the natural size. .--one of the scales (of a species of _beryx_) highly magnified. .--the other scale (of a species of _salmo_). ] [illustration: _plate ii._ _longitudinal section of the pebble._ _page ._] [sidenote: section of the pebble.] section of the pebble. _plate ii._ we will now avail ourselves of the assistance of the lapidary, and divide the pebble in a longitudinal direction;--what a beautiful and interesting section is thus obtained! the markings observable on the fractured portion of the stone (see plate i, c), are thus shown to have originated, as we surmised, from some organic body, which the flint, when fluid, had penetrated and enveloped. the enclosed fossil was obviously one of those soft marine zoophytes, allied to the _actiniæ_ or _sea-anemones_, which are of a globular, spherical, or inversely conical shape, and consist of a tough, jelly-like substance, permeated with tubes, disposed in a radiated manner around a central cavity, or digestive sac; a structure admitting of that constant supply and circulation of sea-water, which the economy of these curious forms of animal existence requires. [sidenote: isle of wight pebbles.] the surface exposed by the division of the pebble, is an oblique vertical section of the petrified zoophyte. it shows a central canal filled with bluish-grey flint (_plate ii, c_), in a mass traversed by tubes or channels, which possess considerable beauty and variety of colour from an impregnation of iron.[l] a transverse section (see _lign. ._ fig. ) would, of course, have a central spot, with rays proceeding thence to the circumference, as in the oblique fracture (_plate i, c_).[m] [l] specimens of this kind form beautiful objects when polished, and are mounted as brooches by the lapidaries of brighton, bognor, and the isle of wight, who term them petrified sea-animal flowers. mr. g. fowlstone ( , victoria arcade) of ryde, has many splendid examples, and also agates and jaspers, the genuine productions of the island. [m] note vii. _isle of wight pebbles._ [sidenote: choanites konigi.] the form of the original zoophyte when living, must have been that of an inverted cone or funnel, (hence the scientific name _choanite_ or funnel-like,) with a long cylindrical digestive cavity in the centre, from which tubes ramified through every part of the mass. it was attached to a rock, stone, or shell, by root-like fibres which spread out from its base; and its soft body was strengthened, as is the case in many sponges and animals of a similar nature, by numerous siliceous spines or spicula, which are often found in the flint and chalk (see _lign. ._ fig. ).[n] [n] note viii. _zoophytes of the chalk._ [illustration: lign. :--choanites _konigi_: from the chalk. fig. .--a transverse section. .--upper portion of the body. .--vertical section, like the pebble, pl. ii. p. . .--a flint, enclosing a choanite, which is exposed on the upper surface. .--various forms of siliceous spines of choanites and other analogous bodies; magnified slightly. (see '_medals of creation_,' p. .) ] the _choanites_ must have swarmed in the chalk ocean, for in some of the strata almost every flint exhibits traces of these zoophytes.[o] [o] the shingle at brighton and bognor in sussex, and in various localities in the isle of wight, abounds in specimens more or less perfect. i would inform my fair readers who may visit these places, and be inclined to purchase a brooch, in illustration of these "_thoughts on a pebble_," that by far the greater number of the so-called brighton and isle of wight moss-agates, jaspers, &c., sold by the lapidaries and jewellers, are of german or scotch origin; and that the _false-emeralds_, and _aquamarines_, are water-worn fragments of common green glass bottles! [sidenote: corals in chalk.] [illustration: lign. :--branch of coral on the pebble. fig. .--a portion magnified. .--a fragment represented as when alive. _a, a_, two polypes collapsed. _b, b_, two polypes with their tentacula extended. ] one more character inscribed on the pebble remains to be interpreted; it is the minute branch of coral partially imbedded in the flint.[p] the surface of this coral, when seen with a powerful lens, is found to be studded with small pores or cells. in a recent state, each cell was inhabited by a living polype or animalcule, which, though permanently united at its base to the general mass, had an independent existence, and possessed sensation and voluntary motion; expanding its thread-like feelers or tentacula to catch its prey, and withdrawing, at will, into its little cell.[q] [p] plate i. immediately below the shell and spine of echinus. [q] for a popular account of recent and fossil corals, see 'wonders of geology,' th edit., vol. ii. lecture vi. p. . [illustration: lign. :--a coral-polype preserved in flint: magnified diameters.] from these investigations, we learn that the pebble, which has formed the subject of our contemplation, had its origin in a living zoophyte that was growing on a rock, in a sea whose boundaries have long since been swept away; that corals, shells, and echini inhabited the bottom of the deep; and that fishes related to existing families, sported in the waters of that ancient ocean. in fine, we have presented to us the scene so exquisitely described by the american poet:-- [sidenote: the coral grove.] the coral grove. deep in the waves is a coral grove. where the purple mullet and gold fish rove, where the sea-flower spreads its leaves of blue, that never are wet with the falling dew. but in bright and changeful beauty shine, far down in the green and glassy brine. the floor is of sand, like the mountain drift. and the pearl-shells spangle the flinty snow; from coral rocks the sea-plants lift their boughs, where the tides and billows flow; the water is calm and still below. for the winds and the waves are absent there, and the sands are bright as the stars that glow in the motionless fields of upper air: there with its waving blade of green, the sea-flag waves through the silent water, and the crimson leaf of the dulse is seen. to blush like a banner bathed in slaughter. there with a light and easy motion the fan-coral sweeps through the clear deep sea; and the yellow and scarlet tufts of ocean, are bending like corn on the upland lea; and life in rare and beautiful forms, is sporting amidst those bowers of stone. percival. [illustration: lign. :--minute corals from the chalk;[r] _highly magnified_.] [r] note ix. _minute corals from the chalk._ [sidenote: microscopic corals.] our previous examination of the pebble had prepared us for these results; but the microscope, that mighty talisman of wisdom, has shown us, that even those infinitesimal creatures to whom a drop of water is an unbounded ocean--those living atoms of that world of being which is for ever concealed from the uninstructed mind--the inhabitants of that universe beneath us, which the eye of science can alone penetrate, existed in ages incalculably remote, and were, like their gigantic contemporaries, the living instruments by which a large proportion of the solid materials of the surface of our planet was elaborated; their imperishable siliceous and calcareous skeletons, constituting no inconsiderable amount of the crust of the earth.[s] [s] see _"thoughts on animalcules, or a glimpse of the invisible world revealed by the microscope_," by the author. published by mr. murray, london, . fossil animalcules and corals similar to those we have discovered in the pebble and in the chalk, and hundreds of other genera and species equally minute, occur in such prodigious numbers, as to warrant the conclusion, that this class of animal existence has contributed more largely than any other, to the formation of the sedimentary strata. not only the chalk hills, but whole mountain-ranges formed of other deposits of great thickness and extent, are found to consist almost entirely of similar remains. in the state of rock, of sand, of clay, of marl--in the coarsest limestone, and in the purest crystal, the petrified skeletons of animalcules alike abound. the town of richmond, in virginia, is built on a bed of stone twenty feet thick, which is wholly composed of the fossil skeletons of different kinds of marine animalcules. the polishing slate of bilin, in germany, is wholly made up of the siliceous shields of similar beings, disposed in layers without any connecting medium; and these belong to species so minute, and are so closely compressed together, that in a cubic inch of the stone, weighing but two hundred and twenty grains, there are the remains of _forty-one thousand millions_ of animalcules![t] [t] see '_medals of creation_,' p. . [illustration: lign. :--animalcules from the richmond earth: very highly magnified[u]] [u] note x. _richmond infusorial earth._ * * * * * [sidenote: reflections.] here we must bring our "_thoughts on a pebble_" to a close; but not without adverting to the pure and elevating gratification which investigations of this nature afford, and the beneficial influence they exert upon the mind and character. in circumstances where the uninstructed and incurious eye can perceive neither novelty nor beauty, he who is imbued with a taste for natural science will everywhere discover an inexhaustible mine of pleasure and instruction, and new and stupendous proofs of the power and goodness of the eternal! for every rock in the desert, every boulder on the plain, every pebble by the brook-side, every grain of sand on the sea-shore, is fraught with lessons of wisdom to the mind which is fitted to receive and comprehend their sublime import. "from millions take thy choice, in all that lives a guide to god is given; ever thou hear'st some guardian angel's voice, when nature speaks of heaven!" amidst the turmoil of the world and the dreary intercourse of common life, we possess in these pursuits a never-failing source of delight, of which nothing can deprive us--an oasis in the desert, to which we may escape, and find a home "wherever the intellect can pierce, and the spirit can breathe the air."[v] for like the plant which the prophet threw into the waters of marah,[w] that changed the bitterness of the wave into sweetness, a branch from the tree of knowledge thrown into the turbid stream of life, purifies its waters, and imparts to them a healing virtue, which sheds a hallowing and refreshing influence over the soul! [v] sir e. bulwer lytton. [w] exod. xv. . the nautilus and the ammonite. (_see page ._) from sketches in prose and verse, by the late g. f. richardson, esq. the nautilus and the ammonite were launch'd in storm and strife; each sent to float, in its tiny boat, on the wide, wild sea of life. and each could swim on the ocean's brim, and anon, its sails could furl; and sink to sleep in the great sea deep, in a palace all of pearl. and their's was a bliss, more fair than this, that we feel in our colder time; for they were rife in a tropic life, in a brighter, happier clime. they swam 'mid isles, whose summer smiles no wintry winds annoy; whose groves were palm, whose air was balm. where life was only joy. they roam'd all day, through creek and bay, and travers'd the ocean deep; and at night they sank on a coral bank, in its fairy bowers to sleep. and the monsters vast, of ages past. they beheld in their ocean caves; and saw them ride, in their power and pride, and sink in their billowy graves. thus hand in hand, from strand to strand, they sail'd in mirth and glee; those fairy shells, with their crystal cells, twin creatures of the sea. but they came at last, to a sea long past, and as they reach'd its shore, the almighty's breath spake out in death, and the ammonite liv'd no more. and the nautilus now, in its shelly prow, as o'er the deep it strays, still seems to seek, in bay and creek, its companion of other days. and thus do we, in life's stormy sea, as we roam from shore to shore; while tempest-tost, seek the lov'd--the lost-- but find them on earth no more! geology, in the magnitude and sublimity of the objects of which it treats, ranks next to astronomy in the scale of the sciences. sir j. f. w. herschel. [illustration] supplementary notes. note i. page . _shells in chalk._ the shells of mollusca, in consequence of their durability, are the most abundant fossils in the sedimentary strata;[x] entire layers of marble and other limestone, of great thickness and extent, are wholly composed of an aggregation of a few species or genera: in some instances of fresh-water snails--as, for example, the sussex and purbeck marbles;[y] in others, of marine bivalves and univalves, as the oyster-conglomerate of bromley, and the shelly limestones of portland, dorsetshire, &c. [x] for an account of the geological value of fossil shells, see '_medals of creation_,' vol. i. p. . [y] see '_wonders of geology_,' th edition, p. . the cretaceous strata contain many hundred species of bivalves and univalves, by far the greater part of which belong to extinct genera; and the species, with but four or five exceptions, are unknown in more recent deposits. in loose sandy strata, fossil shells are oftentimes beautifully preserved, and may be obtained in as perfect a condition as if gathered from the sands on the sea-shores: such is the state of the specimens which abound in the sandy clays near barton in hampshire, and in the "_crag_" of essex and suffolk. in certain beds of clay, shells are also found entire; sometimes retaining the epidermis, and the cartilaginous ligament of the hinge. the bivalves in the white chalk are generally perfect; but the univalves, probably from the more delicate structure of the originals, seldom retain any vestiges of the shell, excepting portions of the internal nacreous coat adhering to the chalk casts, which have been moulded in the interior of the shells. [illustration: lign. :--bivalve shells (_terebratulæ_) from chalk (_natural size_). , . plicated species. . _t. octoplicata._ . _t. subplicata._ , . smooth species. . _t. semiglobosa._ . _t. subrotunda._ ] [sidenote: terebratulÆ from chalk.] in some of the cretaceous strata several extinct species of _oyster_, _scallop_, _arca_, _tellina_, and other well-known marine bivalves abound; and with them are associated many genera of which no living species have been observed. among the bivalves that prevail in the english chalk, are three or four kinds of _terebratulæ_: which are small, elegant, subglobular shells, belonging to a family of which nearly species, referable to several genera, have been obtained from the british strata.[z] certain genera are restricted to the most ancient sedimentary rocks, in which they occur in almost incredible numbers; others have a wider range and are met with in the later secondary deposits; while a few are found in the newest beds, and have living representative species in the seas of warm climates. from the immense antiquity of their lineage, these _terebratulæ_ have been humourously termed the "_fossil aristocracy_." some of the most common chalk species are figured of the natural size in _lign. _. when living the animal was attached to a rock or other body by means of a _byssus_ or peduncle, exserted through the aperture in the beak or curved extremity of the largest valve.[aa] the shells of the smooth _terebratulæ_ are full of minute holes or perforations, which may readily be distinguished with a lens of moderate power. [z] see '_wonders of geology_,' th edit. p. . [aa] in the conchological gallery of the british museum there is a group of thirty or forty recent _terebratulæ_ attached to a stone by their peduncles; from australia. [sidenote: petrified oyster.] [illustration: lign. :--oyster from the chalk, near brighton (natural size).] occasionally the soft body of the mollusk completely silicified--that is, transmuted into flint--is found in its natural position in the shell. a beautiful example of this kind is represented in _lign. _. it is an extinct species of oyster: both valves were entire when i removed the chalk and cleared the specimen; part of one valve has been broken away to expose the petrified body of the animal. i have seen a _trigonia_[ab] from the oolite of tisbury in wiltshire, in which the entire body of the mollusk was transformed into flint, and the _branchiæ_ or lamellated gills were beautifully defined, though converted into semi-transparent chalcedony. [ab] _trigonia:_ a genus of bivalves, of which there are many extinct species in the chalk and oolite; some bands of portland stone are an aggregation of _trigoniæ:_ a few very small species, inhabitants of the seas of australia and new zealand, are the only known living forms of this once prevailing type of mollusca. see '_medals of creation_,' p. . note ii. page . _wood in flint._ [sidenote: wood in flint.] i would remind the reader that the white chalk, together with the various strata of sand, clay, and limestone, comprising the cretaceous formation of england, must be regarded as an ancient ocean-bed; in other words, an accumulation of earthy sediments, formed in the profound depths of the sea, in periods of long duration and of incalculable antiquity, and more or less consolidated by subsequent chemical and mechanical agency. these deposits are made up of organic and inorganic materials: the former consist of the debris of the cliffs and shores which encompassed the ancient ocean, of the spoils of the land brought into the waters by floods and rivers, and of mineral matter thrown down from chemical solutions. the organic substances are the durable remains of the animals and plants which lived and died in the sea, and of terrestrial and fluviatile species that were transported from islands or continents by rivers and their tributaries. the whole constitutes such an assemblage of strata as would probably be presented to observation, if a mass of the bed of the atlantic , feet in thickness, were elevated above the waters, and became dry land; the only essential difference would be in the generic and specific characters of the imbedded animal and vegetable remains. the vestiges of terrestrial and fluviatile animals and plants found in the chalk are comparatively but few: i have collected from kent and sussex, bones of gigantic land lizards, (the _iguanodon_), of flying reptiles, (_pterodactyles_), and of fresh-water turtles, and water-worn fragments of stems of coniferous trees allied to the _araucaria_ or norfolk island pine; fruits or aments of coniferse; and stems and foliage of plants related to the _cycas_ and _zamia_. [illustration: lign. :--fragment of coniferous wood in flint.] a fragment of silicified wood imbedded in a flint, is represented in _lign. _. it was obtained from a wall in lewes priory in sussex; and though it has been exposed to the atmosphere seven or eight centuries, still exhibits the characteristic internal structure. note iii. page . _whitby ammonites._ [sidenote: ammonites.] [illustration: _lign. _:--ammonites from the cretaceous formation. . _ammonites varians_, from hamsey. . _a. dufresnoyi_: _a_, part of the same. . _a. lautus_: _a_, keel and septum of the same. ] the ammonites differ from the nautili in having the margins of the septa or internal shelly partitions (which in the latter are smooth), foliated or wrinkled; and the siphunculus or tube placed along the back of the shell, whereas in the nautilus it is central. the sides of the shell in the ammonites are very generally more or less ornamented with arched elevations and depressions, and studded with spines and tubercles, as in the specimens above figured. there are several kinds of ammonites found in the lias at whitby and other places in yorkshire; the most common species is figured in _lign. _. p. ; the dark colour of this fossil is produced by the argillaceous stone with which it is now filled. the internal structure of these ammonites is generally well preserved, the chambers being lined with spar or other mineral matter; transverse polished sections are often very beautiful from the several cells being occupied by variously coloured marble, susceptible of a high polish. (pl. iii.) in some examples the entire shell is transmuted into brilliant pyrites (sulphuret of iron), and the chambers are filled with white spar; a specimen of this kind in my possession, collected by lady murchison, is the most elegant fossil imaginable. [illustration: _plate iii._ _polished section of an ammonite._ _page ._] [sidenote: ammonite-marble.] it is not unusual for the visitors at whitby to inquire of the collectors how it is that the head of the animal is never found? and the crafty dealers, willing to accommodate the taste of their customers, carve the extremity of an ammonite into the semblance of a serpent's head, and affix two red eyes; thus producing a veritable proof of the truth of the legend of st. hilda! my young readers will not be duped by this trick-of-trade, if they reflect but a moment on the real nature of a fossil ammonite: they will remember that it is a shell which, when empty, became filled with what was then soft mud, but is now stone; in like manner as if liquid plaster of paris were poured into an empty snail-shell and consolidated. in some parts of somersetshire, a beautiful marble composed of an aggregation of two or three small species of ammonites, is used for sideboards and other ornamental purposes: the polished slabs are diversified by the numerous sections of the shells. some of the clays of the lias abound in a species of ammonite of extraordinary beauty from the iridescent lustre of the pearly coat of the shell: a slab of stone from watchett, on which a hundred or more ammonites of this kind are displayed, may be seen in the british museum. note iv. page . _fossil nautili._ the beauty, elegant form, and remarkable internal structure of the shell of the nautilus, have rendered it in all ages an object of curiosity and admiration: yet an accurate knowledge of the organization of the animal to which it belongs, has but recently been obtained. the nautili may be regarded as cuttle-fish or _sepiæ_, inhabiting shells furnished with an apparatus to impart buoyancy, and enable the animals to swim on the surface, or sink to the profound depths of the ocean. a few explanatory remarks on the nature of the recent sepia may be necessary to render the subject intelligible to the unscientific reader. [sidenote: recent nautilus.] the _sepia_ or cuttle-fish of our seas is of an oblong form, and composed of a soft substance covered with a tough integument or skin: it varies from a few inches to a foot or more in length. the mouth is placed in the centre of one extremity of the body, and has a pair of powerful, curved, horny mandibles, much resembling the beaks of a parrot: it is surrounded by eight long arms like the rays of a star-fish, and these are beset with rows of little cups which act as suckers, and enable the animal to secure its prey, and attach itself with great firmness to any object.[ac] it has a distinct head, with two eyes as perfect as in the vertebrated animals, and complicated organs of hearing: and below the head there is a tube or funnel which acts as a locomotive instrument, and propels the animal backwards by the forcible ejection of the water which has served the purpose of respiration, and can be thrown out with considerable force by the contraction of the body. the soft parts are supported by a large internal bone or osselet of a very curious structure, which, when dried and reduced to powder, forms the substance used by scriveners, termed _pounce_. these naked mollusca also possess a membranous bag or sac, containing a dark-coloured fluid resembling ink in appearance, which they eject into the surrounding water upon the approach of danger, and by the obscurity thus induced foil the pursuit of their enemies. this fluid, when inspissated, forms the base of the colour termed _sepia_ by artists. [ac] from this arrangement of the organs of prehension around the head, this order of mollusca is termed the _cephalopoda_; _i. e._, the feet around the head. the body of the nautilus resembles in its essential characters that of the cuttle-fish, and occupies the large outer receptacle of the shell; maintaining a connection with the inner compartments by means of the membranous siphunculus or tube, which is only partially invested with shell. the internal chambers are air-cells, and the animal can fill the siphunculus with fluid, or exhaust it at will; the difference thus effected in its specific gravity enables it to rise to the surface or sink to the bottom with facility. now if' we imagine a cuttle-fish placed in the outer chamber of a nautilus-shell, and provided with a siphuncule, but having neither ink-bag nor osselet--these organs being unnecessary to an animal possessing a chambered shell--we shall have a general idea of the nature of the recent species. the nautilus is essentially an inhabitant of deep water: it creeps along the ground at the bottom of the sea, with its shell upwards like the snail; and by means of its arms can proceed with considerable speed.[ad] [ad] see '_conchologia systematica_,' vol. ii. p. , and '_elements of conchology_,' p. , by mr. lovell reeve, f.l.s., for an admirable description of the recent nautilus, with illustrations. a large and splendid species of fossil nautilus is not uncommon in the london clay of the isle of sheppey, sussex, and hampshire. the chambers are often lined with spar or other brilliant mineral matter; and polished sections, like those of the ammonites, admirably display the internal structure.[ae] [ae] see dr. buckland's '_bridgewater treatise_' for numerous figures of ammonites and nautili; _plates_ to . consult also '_medals of creation_,' vol. ii. p. . note v. page . _brighton cliffs._ [sidenote: brighton cliffs.] the stranger who approaches brighton by the railroads through deep tunnels and cuttings in the chalk, and perceives the town spread over the plain and on the sides of a valley of the south downs, will naturally expect to find the sea-shore bounded by chalk-cliffs. but a wall of admirable construction, extends from the steyne to beyond kemptown, and effectually conceals from view the materials that compose the site of that part of brighton; a ramble along the shore to rottingdean is therefore necessary to reveal to the inquiring observer, the nature of the strata that flank the southern border of the downs. the sketch given in page , represents the appearance of part of the coast to the east of kemptown. the base of the cliff to the height of a few feet, is seen to consist of the white chalk with its usual layers of flint nodules, forming a low wall or terrace, which slopes seaward, and extends far into the british channel--probably to the opposite coast of france: at low-water a considerable expanse of modern shingle and sand is spread over, and in a great measure conceals, the chalk, at a few yards distance from the cliff. upon the terrace of chalk, at the height of from ten to fifteen feet above the modern beach, there is a bed of pebbles and sand, containing also a considerable number of boulders of granite, porphyry, and other crystalline rocks foreign to the south-east of england: in fact, a sea-beach, which must have been formed at some remote period, in the same manner as the modern shingle. upon this ancient beach are strata of loam, and chalk-rubble, with flints partially water-worn, and boulders of sandstone, breccia, granite, &c., constituting the upper sixty or eighty feet of the cliff. in these beds, and also in the ancient shingle, many teeth and bones of mammoths (extinct species of elephant), horse, deer, oxen, and other ruminants, and bones of whales, have been discovered.[af] [af] see '_medals of creation_,' p. . [sidenote: the sussex coast.] a few hundred yards beyond kemptown the inroads of the sea have destroyed all vestiges of the strata above described, and the cliffs consist of a perpendicular wall of chalk; if we extend our walk to rottingdean, we shall perceive here and there isolated patches of the ancient shingle, and of the calcareous strata containing elephants' bones. the appearances described demonstrate the following changes in this part of the sussex coast. _firstly_, the chalk terrace (_lign. , c_; p. ) on which the ancient shingle (_b_) rests, was on a level with the sea for a long period; for this beach must have been accumulated, like the modern, by the action of the waves on the then existing chalk cliffs. but there must also have been some cause not now in operation, by which pebbles, and boulders of granite and other rocks foreign to this coast, with bones of extinct mammalia, &c., were thrown up on the strand, and imbedded in the beach then in progress of formation. these materials were probably brought from some distant part of the then continental shores by floating ice: an agency by which delicate bones and shells may be transported and deposited without injury amidst pebbles and boulders. _secondly._ the whole line of coast with the ancient shingle must have subsided to such a depth as to admit of the deposition of the calcareous materials forming the "elephant bed;" and from the absence of beach and shingle in these strata, it may be inferred that this deposition took place in tranquil water: possibly at that period this part of the sussex coast formed a sheltered bay. _lastly._ the land was elevated to its present level, and the formation of the modern sea-beach and cliffs commenced.[ag] [ag] see '_medals of creation_,' "on the geological structure of brighton cliffs," p. . note vi. page . _rotaliæ in chalk and flint._ [sidenote: fossil foraminifera.] the shells called _rotaliæ_ (see _lign._ and , p. and ) belong to a group of marine animals of very simple organization, and which present great variety in the form and markings of their testaceous coverings; but they all agree in having the sides of the shell pierced by numerous holes or foramina; whence the scientific term of the order, _foraminifera_, is derived: these openings are for the egress of delicate filaments, which appear to be organs of progression and respiration. the _foraminifera_ are, with but few exceptions, exceedingly minute; in an ounce of sea-sand, between three and four millions have been detected. the body of these animalcules consists of uniform granules enclosed in a skin or integument, having one or more digestive sacs or cavities; these creatures appear, in fact, to be mere polypes, protected by testaceous coverings. some have but a single cell; others have many, disposed in a conical or cylindrical form; many kinds, of which the _rotaliæ_ are examples, are discoidal involutes, and divided internally by septa into distinct chambers:[ah] they resemble in this respect the shell of the nautilus, but are readily distinguished by the perforations. [ah] see '_wonders of geology_,' th edit. p. . all the various kinds of _foraminifera_ swarm in the present seas, and were not less numerous in the ancient ocean. we have seen that the white chalk almost wholly consists of a few genera of these animalcules; and in many strata of sand they are so abundant, that a cubic inch of the mass contains upwards of sixty thousand. in the _rotalia_, the body is entirely enclosed within the shell, and occupies all the cells; and long, soft, tentacula are sent off through the foramina. the shell, therefore, though resembling in form that of the nautilus, is essentially different; for in the latter, the outer chamber only is occupied by the body of the animal, the internal ones being successively quitted empty dwellings; whereas, in the _rotaliæ_ and analogous _polythalamia_,[ai] all the cells are contemporaneously filled by the soft parts of the animalcule. [ai] _polythalamia, many-chambered_, is a general term applied to these shells. [sidenote: recent foraminifera.] when the shell is removed, which is readily effected by immersion in diluted hydrochloric acid, the body is exposed, and found to consist of a series of lobes or sacs, united by a tube corresponding somewhat in its position with the siphuncle of the nautilus, but which is the digestive canal. the body of a recent animalcule of this kind, deprived of the shell, is figured in _lign. _. [illustration: lign. :--the body of a recent animalcule allied to the _rotalia_, deprived of its shell; _highly magnified_.] not only the characters of fossil shells of such infinite minuteness can be revealed by the microscope, but even the soft parts of the animalcules which inhabited them; for these are occasionally preserved, and may be demonstrated with as much distinctness as the recent examples.[aj] in flint the soft parts of _rotaliæ_, _textulariæ_, &c., are abundant, and may be seen, with but little preparation, like insects in amber: the specimen figured in _lign. _, p. , shews the body of a _rotalia_ well defined; the only preparation this atom of flint has undergone, is immersion in canada balsam. to detect such delicate structures in chalk requires, however, some experience in microscopic manipulation, as the calcareous matter must be dissolved in hydrochloric acid, and the animal substance separated from the residuum.[ak] [aj] see '_wonders of geology_,' th edit., p. . [ak] see my '_memoir on the fossil remains of the soft parts of foraminifera in chalk, &c._' philosophical transactions, , p. . note vii. page . _isle of wight pebbles._ [sidenote: isle of wight pebbles.] the nodules and veins of flint that are so abundant in the upper chalk, have probably been produced by the agency of heated waters and vapours; the perfect fluidity of the siliceous matter before its consolidation is proved, not only by the sharp moulds and impressions of shells and other organisms retained by the flints, but also by the presence of numerous remains in the substance of the nodules, and the silicified condition of the sponges and other zoophytes which abound in the cretaceous strata. now although silex, or the earth of flint, is but sparingly soluble in water of the ordinary temperature, its solution readily takes places in vapour heated a little above that of fused cast iron, as has been proved by direct experiment;[al] and similar effects are being produced at the present moment by natural causes. the siliceous deposits thrown down by the intermittent boiling fountains, called the geysers, in iceland, are well known;[am] and in new zealand this phenomenon is exhibited on a still grander scale. from the crater of the volcanic mountain of tongariro,[an] which is several thousand feet above the level of the sea, jets of vapour and streams of boiling water highly charged with silex, are continually issuing forth, and dashing down the flanks of the volcano in cascades and torrents, empty themselves into the lakes at its base. as the water cools, siliceous sinter is deposited in vast sheets, and incrustations of flint form around the extraneous substances lying in the course of the thermal streams. silex is also precipitated by the boiling waters in stalagmitic concretions, and in nodules resembling in colour and solidity the flints of the english chalk. the complete impregnation and silicification of organized bodies is attributable to an agency of this kind; and although the origin of the siliceous waters that deposited the nodules and veins of flint in the chalk is still involved in obscurity, the mode in which the latter were formed is satisfactorily elucidated. [al] see '_wonders of geology_,' p. . [am] ibid., p. . [an] ibid., p. . [illustration: lign. :--zoophytes in chalk and flint. . a minute coral from chalk and flint; the lower figure is of the natural size. . branch of a sponge in flint. . pebble enclosing a zoophyte. ] of the perfect transmutation into flint of the most delicate organic structures, the pebbles strewn along the sea-shore of the south coast of england, afford a beautiful illustration; those from the isle of wight are especially celebrated for their rich and varied colours. the most common and interesting are those which exhibit sections of choanites, as in the specimen which suggested the reflections embodied in these pages. other allied forms are scarcely less beautiful; the petrified zoophytes called _siphonia_, which, when living, consisted of a soft mass traversed by tubes, for the free ingress and egress of the water, often display the internal structure of the original: as in the polished transverse section figured above, _lign. , fig. _. other bodies of this class occur in the flint, and present interesting examples of the zoophytes of the chalk ocean. but many of the isle of wight pebbles exhibit no traces of animal structure, yet are valuable and instructive as mineralogical specimens: such are the clear and transparent pebbles with bands and veins of quartz and chalcedony. some specimens are as pellucid as rock-crystal; others are of a bright yellow, amber, dark-brown, and bluish-black colour, and are often mottled with dendritical or arborescent manganese. (_plate iv._) the moss agates, as they are called by the lapidaries, are silicified sponges. small pebbles of pure transparent rock-crystal are often found among the shingle in compton and sandown bays, and have probably been washed out of the wealden strata; for similar stones occur in the tilgate grit, and at tunbridge wells: in the latter place, they are cut and polished for rings, brooches, &c. [illustration: _plate iv._ _polished sections of pebbles._ _page ._] [sidenote: zoophytes of the chalk.] on the shores of the isle of wight, pebbles of jasper, resembling those from egypt, and of banded quartz, with arborescent markings, or with zones of rich brown, are also met with; these do not appear to have originated from the chalk strata. pebbles of silicified wood have been collected in sandown bay by mr. fowlstone; and water-worn boulders and pebbles of petrified wood, bones, &c., are common in brook bay; rolled masses of the fresh-water shelly limestones (sussex and purbeck marbles) are also abundant in the same localities.[ao] [ao] all these varieties may be obtained of mr. fowlstone, , victoria arcade, ryde. note viii. page . _zoophytes of the chalk._ zoophytes, especially sponges, occur in such prodigious numbers in some of the chalk strata, that the nucleus of almost every flint nodule is an organic body. in many instances the silex has completely permeated the animal substance, as in the pebbles before described; but sometimes the sponge is a white calcareous mass, occupying a hollow in the flint: a branched specimen of this kind, exposed on breaking a small nodule, is represented at _lign. , fig. _. in describing sponge as an animal substance, it may be necessary to explain that the sponge in ordinary use is the flexible skeleton of a living zoophyte, and was originally invested with a gelatinous or slimy matter, which lined all the pores and channels. when alive in the water, currents constantly enter the outer pores, traverse all the internal inosculating canals, and issue from the larger orifices which often project above the surface in perforated papillæ. by the circulation of the sea-water through the porous structure, the nutrition of the animated mass is effected; and the modifications observable in the number, size, form, and arrangement of the pores, canals, and apertures, in the different kinds of this type of organization, are subservient to this especial function. but associated with the true _poriferæ_ or sponges, are numerous zoophytes which resemble them in form, but are of an entirely distinct nature; for they are the fossilized remains of _polyparia_, that is, of the frame-work of an aggregation of polypes, each individual of which had an independent existence, although the whole were united by one common living integument, like the _alcyonium_, or dead-men's fingers, of our coasts.[ap] [ap] see '_medals of creation_,' p. . [illustration: lign. :--flints deriving their forms from the zoophytes they enclose.] [sidenote: fungiform flints.] among the flints whose forms depend on the organic bodies they enclose, are some which bear so close a resemblance in shape to _fungi_, that they are provincially called in sussex "_petrified mushrooms_;" several of them are figured above (_lign. _). in these fossils there are openings at the base, and a groove on the margin of the upper part, in which the structure of the enclosed body is generally more or less distinctly seen; and upon breaking one of these bodies, a section of a funnel-shaped zoophyte is obtained. the origin of these flints will be understood by reference to the four interesting specimens here delineated, one-sixth of the natural size in linear dimensions. [illustration: lign. :--ventriculites from the chalk, lewes. . a perfect specimen in chalk, shewing the external net-like surface. . an expanded specimen, displaying the inner surface studded with cells. . a ventriculite with the lower part enveloped in flint. . part of a ventriculite; the base invested with flint: the root-like fibres are seen at a. ] [sidenote: ventriculites.] this zoophyte, to which the name of _ventriculite_ has been given to denote its usual shape, was a hollow inverted cone, terminating at the base in a point, whence radicles or root-like processes were sent off, by which the animal was firmly attached to the rock. the outer integument was disposed in meshes like a net (see _lign. , fig. _), and the inner surface was beset with regular circular openings, the orifices of tubular cells (_fig. _); each of which was probably occupied by a polype. the substance of the _polyparium_, or general support of this family of animalcules, which alone occurs in a fossil state, appears to have been analogous to that of the soft _alcyonia_, and to have possessed a common irritability; the entire mass contracting and expanding, as is the case in many recent zoophytes.[aq] [aq] see '_wonders of geology_,' th ed., p. ; '_medals of creation_,' p. - ; and '_geological excursions round the isle of wight_,' pp. - , for an account of the silicification of these and other zoophytes. the flints, _figs. , , , , lign. _, were evidently formed in the manner exemplified in _fig. , lign. _; _figs._ , , , are illustrated by _fig. , lign. _; for the chalk specimens, _lign. _, shew that all these flints have been moulded around _ventriculites_, and that their diversity of figure has arisen from the quantity of silex that happened to permeate the substance of the zoophyte; if but a small portion, flint like _figs._ and , were the result; if the quantity were considerable, the larger fungiform examples were produced. note ix. page . _minute corals from chalk._ some layers of chalk are composed of an aggregation of many kinds of delicate corals, the interstices being filled up with _rotaliæ_ and other foraminiferous shells. in the cliffs near dover there are several beds of this nature, well known to collectors for the profusion of exquisite specimens they yield to the experienced investigator. _lign. _, p. , represents several varieties from different localities; the small figures shew the natural size, and the enlarged ones their appearance when magnified. attached to the surface of shells, and sometimes standing erect in crannies of flint nodules, beautiful corals may often be detected by the aid of a lens of moderate power. by brushing chalk in water, and examining the deposit, delicate fossils of this kind may also be obtained.[ar] [ar] refer to '_medals of creation_,' p. , and to '_wonders of geology_,' _lecture vi._ p. , for a comprehensive view of recent and fossil corals. [sidenote: nature of corals.] from the close analogy of the fossil corals to existing forms, it would not be difficult to give restored figures of the originals. every little branch might be represented fraught with living polypes: in some cells the agile inmates might be shown with the mouth expanded, and the tentacula in rapid motion; in others withdrawn into their stony recesses, and devouring the infinitesimal atoms that constitute their food: even their varied hues might be introduced, and thus a vivid picture be presented of the microscopic beings which peopled the waters of the ancient chalk ocean. that the corals, which from their elegance and beauty are preserved in almost every cabinet, have been fabricated--or, in other words, built up--by polypes, in the same manner as the honey-comb of the bee and wasp, is so prevalent yet erroneous an opinion, that i am induced to point out its fallacy, by giving a brief account of the formation of these substances. the three recent specimens represented in _lign. _ will serve to illustrate my remarks. [illustration: lign. :--recent corals. . _oculina ramea._ . _madrepora muricata._ . _isis hippuris._ ] the coral, _fig. _, was an internal axis or skeleton, deposited by the soft fleshy integument with which, when living, it was wholly invested; in the same manner as are the bones of animals, by the special membrane (_periosteum_) that secretes them. this integument lined every cell, and the polypes were permanently united to it. when the live coral is taken out of the water, the animalcules shrink up and quickly perish; their soft parts and the external investing substance putrefy, and the stony axis beset with the radiated cells alone remains. [sidenote: recent corals.] in the example of _oculina ramea_, or may-blossom coral, _fig. _, from the mediterranean, the cells are large and distinct; in the _madrepore_ from the west indies, _fig. _, they are small and very closely aggregated. the specimen of _isis_ (_fig. _) belongs to a group of coral-zoophytes in which the polype-cells consist of a substance that is durable, but not so hard as coral, and invests an axis composed of a tough flexible material, which is exposed at the base of _fig _, by the removal of the external or cortical part in which the polypes were situated. the _gorgonia_, or venus's fan, has a similar structure and composition.[as] [as] see '_wonders of geology_,' vol. ii. p. . in the _red coral_, so largely employed in the manufacture of beads, brooches, and other ornaments, not only the animalcules, but also their receptacles, are composed of a soft perishable substance. when alive, the polypes, as well as the investing fleshy integument, are of a delicate bluish tint; the internal calcareous axis alone possesses the peculiar red colour. upon being taken out of the sea, vitality quickly ceases, the soft parts decompose, and the beautiful crimson stone commonly known as the _true coral_, is obtained free from all traces of the soft mass by which it was secreted. although an actual investigation of the facts described can only be instituted near the seas of warm climates, yet our coasts abound in certain coral-zoophytes in which similar phenomena may readily be observed. most persons in their rambles by the sea-side must have noticed on the fuci, algæ, shells, pebbles, &c., patches of a white earthy substance, which when closely examined resemble delicate lace-work. these apparently calcareous incrustations are clusters of the zoophytes termed the _flustra_, or sea-mat.[at] when removed from the water, this aggregation of polypes seems coated over with a glossy film or varnish; and with a lens of moderate power the surface is seen to be full of pores, disposed with much regularity. if viewed under the microscope while immersed in sea-water, a very different appearance is presented. every pore is found to be the opening of a cell whence issues a tube fringed with several long feelers or arms; these expand, then suddenly contract and withdraw into the cell, and again issue forth; the whole surface of the flustra being covered with these hydra-like animalcules. the flustra, therefore, like the corals, constitutes an assemblage of polypes, each individual being permanently fixed in a durable cell, and the whole attached to a common integument by which the calcareous frame-work was secreted and maintained.[au] [at] see '_wonders of geology_,' plate . [au] see dr. johnson's beautiful work on '_british zoophytes_,' in which are numerous figures of various species of flustra. note x. page . _infusorial earth from richmond in virginia._ [sidenote: infusorial earths.] the greatest natural operations are produced by the most simple and apparently inadequate agents: for as the illustrious galileo emphatically remarked, "_la nature fait beaucoup avec peu, et ses opérations sont toutes également merveilleuses._" the profound thinker hobbes, in the same spirit observes, "the majesty of god appeareth no less in small things than in great, and as it exceedeth human sense in the immensity of the universe, so also doth it in the smallness of the parts thereof." this sublime truth is strongly impressed on the mind of the geological inquirer, who perceives that whole countries and mountain ranges of great elevation and extent, are wholly composed of the aggregated remains of beings of such infinite minuteness that but for the powerful optical instruments of modern times, their presence would never have been suspected. a few years only have elapsed since the sagacious ehrenberg first drew attention to this subject, and pointed out the proper method of investigation;[av] and so rapid has been the progress of discovery in this department of science, that _infusorial deposits_, as these beds of fossil animalcules are designated, have been detected in every quarter of the globe. a fact equally unexpected and remarkable has also been established, namely, that at the present moment similar minute living agents are largely contributing to the increase of the solid materials of the crust of our planet. [av] see '_medals of creation_,' p. , for instructions for the microscopical examination of earths, chalk, &c. [sidenote: richmond earth.] the infusorial earth of virginia, alluded to in the text, is a yellowish siliceous clay, forming a deposit from twelve to fifteen feet in thickness, upon which the towns of richmond and petersburgh are built. the surface of the country over which it extends is characterized by a scanty vegetation, owing to the siliceous nature of the soil dependent on the minute organisms of which it almost entirely consists. when a few grains of this earth are properly prepared for microscopic examination, immense numbers of the shields or cases of animalcules are visible under a magnifying power of diameters; in fact, the merest stain left by the evaporation of water in which some of the marl has been mixed, teems with these fossil remains.[aw] [aw] specimens of infusorial earths, prepared for the microscope, may be obtained of mr. topping, , new winchester street, pentonville hill, new road, london. these organisms are of exquisite structure, and comprise many species and genera. the most beautiful and abundant are the circular shields, termed _coscinodisci_ (sieve-like disks), which are elegant saucer-shaped cases, elaborately ornamented with hexagonal apertures disposed in curves, somewhat resembling the engine-turned sculpturing of a watch; these shells are from / to / of an inch in diameter. a segment of one of these disks, highly magnified, is represented in _lign. , fig. _. the body of the living animalcule was protected and enclosed by a pair of these concave shells, the perforations admitting of the exsertion of filaments or tentacula. this species of _coscinodiscus_ abounds in the present seas, and constitutes no inconsiderable proportion of the food of pectens and other testaceous mollusca.[ax] [ax] see '_thoughts on animalcules_,' p. . all the animalcules found in the richmond earth are marine, and most of them belong to genera, and many to existing species; although the position of the american strata proves that they are referable to a period of immense antiquity. in germany, beds of a white infusorial earth, resembling magnesia in appearance, and termed _bergh-mehl_, or fossil farina, occur at bilin, and several other places: at san fiora in tuscany, near egra in bohemia, in the bermudas, barbadoes, &c., similar deposits have been discovered; all being composed of the shields of various kinds of animalcules. but i must not extend these remarks, and will only add a few observations on the infusorial earth of barbadoes, which has but recently been brought under the notice of geologists by sir robert schomburgk, and is especially interesting for the exquisite beauty and variety of its organisms, and the circumstances under which the deposit occurs. [sidenote: fossil infusoria of barbadoes.] barbadoes, an island of the west indies, is about twelve miles in length from north to south, and consists of coral reefs, capped in one district by tertiary sandstones and limestones, which attain a height of feet above the sea. over the rest of the island, coral reefs form the entire surface, which is divided by vertical walls of coral, some of them nearly feet high, into six terraces, indicating as many periods of upheaval. in the lowest reef, indian hatchets have been found twenty feet above high water mark; shewing that the last movement, at least, took place within the human period. the tertiary strata are more or less inclined, and in many places vertical, and contorted. strata of marl, several hundred feet thick, predominate; and there are beds of bituminous coal, sandstone, clays, and ferruginous sands. arenaceous limestone containing teeth of sharks, spines of echini, and shells, forms the summit of a hill nearly , feet high. the white marls abound in species of the most beautiful siliceous infusoria; many are peculiar, others the same as occur in the richmond earth, and some belong to recent species.[ay] [ay] sir r. h. schomburgk: brit. assoc. . the end. * * * * * works by the same author. _in vols, foolscap vo, cloth, lettered, with numerous illustrations and coloured plates, price s. the sixth edition of_ the wonders of geology; or, a familiar exposition of geological phenomena. by gideon algernon mantell, esq., ll.d., f.r.s, vice-president of the geological society of london. 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or, figures and descriptions of the shells of molluscous animals. by lovell reeve, f.l.s. demy to. monthly. eight plates. _s._ coloured. part just published. . elements of conchology; or, introduction to the natural history of shells and their molluscous inhabitants. by lovell reeve, f.l.s. royal vo. in twelve parts, each containing five plates. price _s._ _d._ coloured. . curtis's british entomology. re-issued in monthly parts, each containing coloured plates and corresponding text. price _s._ _d._ . a century of orchidaceous plants. published in monthly numbers, each containing five plates. price _s._ london: reeve and benham, henrietta street, covent garden. * * * * * transcriber note illustrations may have been moved to prevent splitting paragraphs. minor typos were corrected. produced from materials made available on the internet archive and all derived products are placed in the public domain. university of kansas publications museum of natural history volume , no. , pp. - , figs. march , records of the fossil mammal sinclairella, family apatemyidae, from the chadronian and orellan by william a. clemens, jr. university of kansas lawrence university of kansas publications, museum of natural history editors: e. raymond hall, chairman, henry s. fitch, theodore h. eaton, jr. volume , no. , pp. - , figs. published march , university of kansas lawrence, kansas printed by harry (bud) timberlake, state printer topeka, kansas - records of the fossil mammal sinclairella, family apatemyidae, from the chadronian and orellan by william a. clemens, jr. introduction the family apatemyidae has a long geochronological range in north america, beginning in the torrejonian land-mammal age, but is represented by a relatively small number of fossils found at a few localities. two fossils of orellan age, found in northeastern colorado and described here, demonstrate that the geochronological range of the apatemyidae extends into the middle oligocene. isolated teeth of _sinclairella dakotensis_ jepsen, part of a sample of a chadronian local fauna collected by field parties from the webb school of california, are also described. i thank mr. raymond m. alf, webb school of california, claremont, california, and dr. peter robinson, university of colorado museum, boulder, colorado, for permitting me to describe the fossils they discovered. also dr. robinson made available the draft of a short paper he had prepared on the tooth found in weld county, colorado; his work was facilitated by a grant from the university of colorado council on research and creative work. i also gratefully acknowledge receipt of critical data and valuable comments from drs. edwin c. galbreath, glenn l. jepsen, and malcolm c. mckenna who is currently revising the paleocene apatemyids and studying the phylogenetic relationships of the family. the prefixes of catalogue numbers used in the text identify fossils in the collections of the following institutions: ku, museum of natural history, the university of kansas, lawrence; princeton, princeton museum, princeton, new jersey; ram-ucr, raymond alf museum, webb school of california, claremont, california (the permanent repository for these specimens will be the university of california, riverside); and ucm, university of colorado museum, boulder, colorado. the system of notations for teeth prescribed for use here is as follows: teeth in the upper half of the dentition are designated by a capital letter and a number; thus m is the notation for the upper second molar; teeth in the lower half of the dentition are designated by a lower-case letter and a number; thus p is the notation for the lower second premolar. family apatemyidae matthew, genus =sinclairella= jepsen, =sinclairella dakotensis= jepsen, the type of the species, princeton no. , was discovered in chadronian strata of the upper part of the chadron formation cropping out in big corral draw, approximately miles south-southwest of scenic, in southwestern south dakota (jepsen, , p. ). detailed descriptions of the type specimen are given in papers by jepsen ( ) and scott and jepsen ( ). isolated teeth of chadronian age referable to _sinclairella dakotensis_ have been discovered subsequently at a locality in nebraska and fossils of orellan age, also referable to _s. dakotensis_, have been collected at two localities in colorado. the sample from each locality is described separately. sioux county, northwestern nebraska _material._--ram-ucr nos. , left m ; , left m ; , right m ; , right m ; , right m ; , right m ; and , left m . _locality and stratigraphy._--these chadronian fossils were discovered by raymond alf and members of his field parties in several harvester ant mounds built in exposures of the chadron formation in sec. , t n, r w, sioux county, nebraska (alf, , and hough and alf, ). this is ucr locality v . the collectors carefully considered the possibility that some of the fossils found in the ant mounds were collected from younger strata by the harvester ants and concluded this was unlikely (alf, personal communication). _description and comments._--the cusps of ram-ucr no. , a left m , are sharp and the wear-facets resulting from occlusion with the lower dentition are small. the paraconule is a low, ill-defined cusp on the anterior margin of the crown; a metaconule is not present. a smooth stylar shelf is present labial to the metacone. the crown was supported by three roots. there are no interradicular crests. the crown of ram-ucr no. , a right m , is heavily abraded and many morphological details of the cusps have been destroyed. low interradicular crests linked the three roots of the tooth with a low, central prominence. as was the case with ram-ucr no. , no significant differences could be found in comparisons with illustrations of the teeth preserved in princeton no. . ram-ucr nos. , , , and all appear to be m 's. the talonids of these teeth are not elongated, their trigonids have quadrilateral outlines, and the paraconids are small but prominent, bladelike cusps. the trigonid of ram-ucr is elongated and the paraconid is a minute cusp; the tooth closely resembles the m of the type of _sinclairella dakotensis_. logan county, northeastern colorado _material._--ku no. (fig. ), a fragment of a left maxillary containing p and m - . _locality and stratigraphy._--the fossil was found in the center of the w- / , sec. , t n, r w, logan county, colorado, "... in the bed below _agnotocastor_ bed, cedar creek member...." (ronald h. pine, , field notes on file at the university of kansas). the bed so defined is part of unit in the lower division of the cedar creek member, as subdivided by galbreath ( : ) in stratigraphic section xii. the fauna obtained from unit is of orellan age. [illustration: fig. . _sinclairella dakotensis_ jepsen, ku no. , fragment of left maxillary with p and m - ; orellan, logan county, colorado; drawings by mrs. judith hood: a, labial view; b, occlusal view; both approximately × .] _description and comments._--p of ku no. has a large posterolingual cusp separated from the main cusp by a distinct groove, which deepens posteriorly. the posterolingual cusp is supported by the broad posterior root. p of the type specimen of _sinclairella dakotensis_ is described (jepsen, , p. ) as having an oval outline at the base of the crown, and a small, posterolingual cusp. a chip of enamel is missing from the posterior slope of the main cusp of the p of ku no. . the anterior slope of the main cusp is flattened, possibly the result of wear, and there is no evidence of a groove like that present on the p of the type specimen. only a few differences were found between the molars preserved in ku no. and their counterparts in the type specimen. a stylar shelf is present labial to the metacone of m of ku no. , but, unlike the type, its surface is smooth and there is no evidence of cusps. of the three small stylar cusps on the stylar shelf of m the smallest is in the position of a mesostyle. the m lacks a chip of enamel from the lingual surface of the hypocone. unlike the m of princeton no. , in occlusal view the posterior margin of the m of ku no. is convex posterior to the metacone. the anterior edge of the base of the zygomatic arch of ku no. was dorsal to m . the shallow oval depression in the maxillary dorsal to m might be the result of post-mortem distortion. the molars preserved in ku no. and their counterparts in the type specimen do not appear to be significantly different in size (table ) or morphology of the cusps. the only difference between the two specimens that might be of classificatory significance is the difference in size of the posterolingual cusp of p . at present the range of intraspecific variation in the morphology of p has not been documented for any species of apatemyid. the evolutionary trend or trends of the apatemyids (mckenna, , p. ) for progressive reduction of function of p probably were paralleled by similar trends in the evolution of the p . if so, the intraspecific variation in the morphology of p could be expected to be somewhat greater than that of the upper molars, for example. the morphological difference between the p 's of the type of _sinclairella dakotensis_ and ku no. is not extreme and does not exceed the range of intraspecific variation that could be expected for this element of the dentition. the close resemblances in size and morphology between the m - of princeton no. and ku no. also favor identification of the latter as part of a member of an orellan population of _sinclairella dakotensis_. weld county, northeastern colorado [illustration: fig. . _sinclairella dakotensis_ jepsen, ucm no. , right m ; orellan, weld county, colorado; drawing by mrs. judith hood: occlusal view, approximately × .] _material._--ucm no. (fig. ), is a right m . _locality and stratigraphy._--the tooth was discovered at the mellinger locality, sec. , t n, r w, weld county, colorado. the mellinger locality is in the cedar creek member, white river formation, and its fauna is considered to be of orellan age (patterson and mcgrew, , and galbreath, ). _description and comments._--ucm no. , which is more heavily abraded than ku no. , shows no evidence of a stylar cusp either anterolabial to the metacone or in the position of a mesostyle. a small stylar cusp is present anterolabial to the paracone. a notch that appears to have been cut through the enamel of the posterolabial corner of the crown could have received the parastylar apex of m . a similar notch is not present on the m of ku no. nor indicated in the illustrations of the m of princeton no. . the coronal dimensions of ucm no. (table ) do not appear to differ significantly from those of the m 's of ku no. and the type specimen of _sinclairella dakotensis_. comments with the discovery of orellan apatemyids the geochronological range of the family in north america is shown to extend from the torrejonian through the orellan land-mammal ages. the discoveries reported here enlarge the oligocene record of apatemyids to include not only the type specimen of _sinclairella dakotensis_, a skull and associated mandible from south dakota, but also seven isolated teeth, representing at least two individuals, from a chadronian fossil locality in nebraska and one specimen from each of two orellan fossil localities in northeastern colorado. simpson ( : , and : ) presented tabulations of the published records of american apatemyids and suggested the data indicated the populations of these mammals were of small size throughout the history of the family. the few pre-oligocene occurrences of apatemyids described subsequently (note mckenna, , figs. - , and p. ) and occurrences described here tend to reinforce simpson's interpretation. this interpretation may have to be modified to some degree, however, when current studies of collections of pre-oligocene apatemyids are completed (mckenna, personal communication). although information concerning the evolutionary trends of american apatemyids has been published, no data on the morphological variation in a population are available in the literature. an adequate basis for evaluating the significance of the morphological differences between the p 's of princeton no. and ku no. coupled with the similarities of their m - 's is lacking. in the evolution of american apatemyids the p underwent reduction in size and, apparently, curtailment of function. this history suggests the range of morphological variation of p in populations of _sinclairella dakotensis_ could be expected to be greater than that of the molars and encompass the morphological differences between the p 's of princeton no. and ku no. . the difference in age of the chadronian and orellan fossils does not constitute proof that they pertain to different species. although the identification is admittedly provisional until more fossils including other parts of the skeleton are discovered, the orellan fossils described here are referred to _sinclairella dakotensis_. table .--measurements (in millimeters) of teeth of sinclairella dakotensis jepsen. ========================================================================== | p | m | m -----------------------+------------+------------------+------------------ |length|width|length[ ]|width[ ]|length[ ]|width[ ] -----------------------+------+-----+---------+--------+---------+-------- princeton no. [ ] | . | . | . | . | . | . ram no. | | | . | . | | ram no. | | | | | . | . ku no. | . | . | . | . | . | . + ucm no. | | | | | . | . -----------------------+------+-----+---------+--------+---------+-------- | m | m +---------+--------+---------+-------- | length | width | length | width +---------+--------+---------+-------- princeton no. [ ] | . | . | . | . ram no. | . | . | | ram no. | | | . | . ram no. | | | . + | . ram no. | | | . | . ram no. | | | . | . ------------------------------------+---------+--------+---------+-------- [footnote : length defined as maximum dimension of the labial half of the crown measured parallel to a line drawn through the apices of paracone and metacone. width defined as maximum coronal dimension measured along line perpendicular to line defined by apices of paracone and metacone.] [footnote : dimensions provided by dr. glenn l. jepsen.] [footnote : dimensions taken from jepsen ( : ).] literature cited alf, r. . a new species of the rodent _pipestoneomys_ from the oligocene of nebraska. breviora, mus. comp. zool., no. , pp. - , figs. galbreath, e. c. . a contribution to the tertiary geology and paleontology of northeastern colorado. univ. kansas paleont. cont., vertebrata, art. , pp. - , pls., figs. hough, j., and alf, r. . a chadron mammalian fauna from nebraska. journ. paleon. : - , figs. jepsen, g. l. . a revision of the american apatemyidae and the description of a new genus, _sinclairella_, from the white river oligocene of south dakota. proc. amer. philos. soc., : - , pls., figs. mckenna, m. c. . fossil mammalia from the early wasatchian four mile fauna, eocene of northwest colorado. univ. california publ. in geol. sci., : - , figs. matthew, w. d. . the carnivora and insectivora of the bridger basin, middle eocene. mem. amer. mus. nat. hist., : - , pls. - , figs. patterson, b. and mcgrew, p. o. . a soricid and two erinaceids from the white river oligocene. geol. ser., field mus. nat. hist., : - , figs. - . scott, w. b. and jepsen, g. l. . the mammalian fauna of the white river oligocene--part i. insectivora and carnivora. trans. amer. philos. soc., n. s., : - , pls., figs. simpson, g. g. . tempo and mode in evolution. new york: columbia univ. press, xviii + pp., figs. . the major features of evolution. new york: columbia univ. press, xx + pp., figs. _transmitted june , ._ university of kansas publications museum of natural history volume , no. , pp. - , figs. october , a new genus of pennsylvanian fish (crossopterygii, coelacanthiformes) from kansas by joan echols university of kansas lawrence university of kansas publications, museum of natural history editors: e. raymond hall, chairman, henry s. fitch, theodore h. eaton, jr. ~volume , no. , pp. - , figs.~ ~published october , ~ university of kansas lawrence, kansas printed by jean m. neibarger, state printer topeka, kansas [transcriber's note: words surrounded by tildes, like ~this~ signifies words in bold. words surrounded by underscores, like _this_, signifies words in italics.] a new genus of pennsylvanian fish (crossopterygii, coelacanthiformes) from kansas by joan echols introduction in and , h. h. lane, c. w. hibbard and w. k. mcnown collected the specimens that hibbard ( ) described and made the basis of two new species. these were from the rock lake shale member of the stanton formation, six miles northwest of garnett, anderson county, kansas. in , from a locality (kan- /d, see page ) approximately one fourth mile southwest of the first locality, specimens were quarried by f. e. peabody, r. w. wilson and r. weeks. in r. r. camp collected additional blocks of rock lake shale from this second locality. study of all of the materials from the above mentioned localities reveals the existence of an hitherto unrecognized genus of coelacanth. it is named and described below. i wish to thank prof. theodore h. eaton, jr., for suggesting the project and for much helpful advice. i am indebted to dr. e. i. white of the british museum (natural history) for furnishing a cast of the endocranium of _rhabdoderma elegans_ (newberry) for comparison, and to drs. donald baird (princeton university), bobb schaeffer (american museum of natural history) and r. h. denison (chicago natural history museum) for loans and exchanges of specimens for comparison. i am grateful to dr. bobb schaeffer for advice on the manuscript. mr. merton c. bowman assisted with the illustrations. the study here reported on was made while i was a research assistant supported by national science foundation grant g- . systematic descriptions subclass crossopterygii superorder coelacanthi order coelacanthiformes suborder diplocercidoidei family diplocercidae subfamily ~rhabdodermatinae~, new subfamily _type genus._--_rhabdoderma reis_, , paleontographica, vol. , p. . _referred genus._--_synaptotylus_ new, described below. _horizon._--carboniferous. _diagnosis._--sphenethmoid region partly ossified, and consisting of basisphenoid, parasphenoid, and ethmoid ossifications; paired basipterygoid process and paired antotic process on basisphenoid; parasphenoid of normal size, and closely associated with, or fused to, basisphenoid; ethmoids paired in _rhabdoderma_ (unknown in _synaptotylus_). _discussion._--because of the great differences in endocranial structure between the devonian and pennsylvanian coelacanths, they are here placed in new subfamilies. the two proposed subfamilies of the family diplocercidae are the diplocercinae and the rhabdodermatinae. the diplocercinae include those coelacanths having two large unpaired bones in the endocranium (at present this includes _diplocercides_ stensiö, _nesides_ stensiö and _euporosteus_ jaekel). the subfamily rhabdodermatinae is composed of coelacanths having reduced endocranial ossification, as described in detail above, and now including _rhabdoderma_ reis and _synaptotylus_ n. g. members of this subfamily differ from those of the subfamily diplocercinae in having several paired and unpaired elements in the sphenethmoid region of the endocranium, instead of only one larger ossification. they differ from those of the suborder coelacanthoidei in the retention of basipterygoid processes. _synaptotylus_ is more closely related to _rhabdoderma_ than to the diplocercines because the anterior portion of the endocranium contains only a basisphenoid, parasphenoid, and probably ethmoids. the sphenethmoid region was certainly not a large, unpaired unit as in the diplocercines. probably the posterior part, the otico-occipital region (not known in _synaptotylus_), was much more nearly like that of _rhabdoderma_, which consisted of unpaired basioccipital and supraoccipital, and paired prootics, exoccipitals, and anterior and posterior occipital ossifications (moy-thomas, : figs. , ). moy-thomas ( : ) points out that in _rhabdoderma_ the occipital region is "considerably more ossified" than in any coelacanths other than the devonian forms. berg ( : ) thought that the carboniferous coelacanths should be placed in a separate family because they did not have two large, unpaired bones in the endocranium. _rhabdoderma_ and _synaptotylus_ represent another stage in evolution of the endocranium in coelacanths, and, if classification is to be based on endocranial structure, then this stage (represented by the two genera) may later be given family rank as berg suggested. because _rhabdoderma_ and _synaptotylus_ have only part of the sphenethmoid region ossified and because they retain basipterygoid processes, they are considered to be related and are included in the subfamily rhabdodermatinae. ~synaptotylus~, new genus _type species._--_synaptotylus newelli_ (hibbard). _horizon._--rock lake shale member, stanton formation, lansing group, missouri series, upper pennsylvanian. _diagnosis._--late pennsylvanian fishes of small size, having the following combination of characters: on basisphenoid, knoblike antotic processes connected by a low ridge to basipterygoid processes; entire ventral surface of parasphenoid toothed; anterior margin of parasphenoid notched and no evidence of hypophyseal opening. dermal bones of skull smooth or with low, rounded tubercles and striae; fronto-ethmoid shield incompletely known but having one pair of large rectangular frontals with posterolaterally slanting anterior margins; intertemporals large, the lateral margins curving laterally; postorbital triangular, apex downward; subopercular somewhat triangular; squamosal carrying sensory canal that curves down posteriorly and extends onto a ventral projection; opercular generally triangular; supratemporals elongate, curving to fit lateral margin of intertemporals; circumorbital plates lightly ossified. palatoquadrate complex consisting of endopterygoid and ectopterygoid (both toothed on medial surface), quadrate, and metapterygoid, the latter smooth and having widened border for articulation on anterodorsal margin. pectoral girdle consisting of cleithrum and clavicle (supracleithrum not seen); small projection on medial surface of posterior portion of cleithrum; horizontal medial process on clavicle. pelvic plate bearing three anteriorly diverging apophyses, and one denticulate ventromedian process for articulation to opposite plate. lepidotrichia jointed distally, but not tuberculated. scales oval, having posteriorly converging ridges on posterior exposed parts. the name refers to the most distinctive character of the genus, the connected antotic and basipterygoid processes on the basisphenoid, and is derived from greek, _synaptos_--joined, _tylos_ (masc.)--knob, projection. _synaptotylus_ is excluded from the advanced suborder coelacanthoidei by the retention of basipterygoid processes on the basisphenoid. _synaptotylus_ differs from _rhabdoderma_ in several characters of the basisphenoid, the most important being: knoblike antotic processes (those of _rhabdoderma_ are wider, more flattened and more dorsal in position); small, lateral basipterygoid processes (in _rhabdoderma_ these are larger and farther ventral in position). ~synaptotylus newelli~ (hibbard) _coelacanthus newelli_ hibbard, , univ. kansas sci. bull., : , pl. , figs. , . _coelacanthus arcuatus_ hibbard, , univ. kansas sci. bull., : , pl. , fig. ; pl. , fig. . _rhabdoderma elegans_ moy-thomas, (in part), proc. zool. soc. london, (ser. b, pt. ): . _type._--k. u. no. f. _diagnosis._--same as for the genus. _horizon._--rock lake shale member, stanton formation, lansing group, missouri series, upper pennsylvanian. _localities._--the specimens studied by hibbard (k. u. nos. f, f, ) and no. were taken from the bradford chandler farm, from the original quarry in sw- / , se- / , sec. , t. s, r. e. the remainder were collected from university of kansas museum of natural history locality kan- /d, a quarry in sec. , t. s, r. e. both of these are approximately six miles northwest of garnett, anderson county, kansas. _referred specimens._--k. u. nos. f, f, , , , , , , , , , , , , , , , , , , , , . _preservation._--preservation of many of the specimens is good, few are weathered, but most of the remains are fragmentary and dissociated. one specimen (the type, no. f) and half of another were nearly complete. specimens are found scattered throughout the rock lake shale (see p. ). _morphology._--terminology used for bones of the skull is that of moy-thomas ( ) and schaeffer ( ). _endocranium and parasphenoid_ [illustration: fig. . _synaptotylus newelli_ (hibbard). restoration of the basisphenoid, based on k. u. no. , × . a, lateral view, b, posterior view, c, ventral view.] the basisphenoid (see fig. ) has been observed in only one specimen (k. u. no. ) in posterodorsal and ventral views. the basisphenoid, although somewhat crushed, appears to be fused to the parasphenoid. both antotic and basipterygoid processes are present, and are connected by a low, rounded ridge. the antotic processes are large, bulbar projections. these processes in _rhabdoderma_ are wider and more flattened (moy-thomas, :figs. , ). the antotic processes are at mid-point on the lateral surface, not dorsal as in _rhabdoderma_, and both the processes and the ridge are directed anteroventrally. the basipterygoid processes are smaller, somewhat vertically elongated projections, situated at the end of the low connecting ridge extending anteroventrally from the antotic processes, and are not basal as are those of _rhabdoderma_. the sphenoid condyles, seen in posterior view, issue from the dorsal margin of the notochordal socket. the margins of the socket are rounded, and slope down evenly to the center. a slight depression situated between and dorsal to the sphenoid condyles is supposedly for the attachment of the intercranial ligament (schaeffer and gregory, :fig. ). the alisphenoids extend upward, anterodorsally from the region above the sphenoid condyles, and may connect to ridges on the ventral surface of the frontals. the lateral laminae are not preserved, and their extent is unknown. in viewing the changes in the endocranium of carboniferous and permian coelacanths, it would be well to consider the mechanical relationship of the loss of the basipterygoid processes to the effect on swallowing prey. evidently many of the coelacanths, _latimeria_ for example, are predators (smith, : ); to such fishes a more efficient catching and swallowing mechanism would be an adaptive improvement. stensiö ( :fig. ) presents a cross section of the ethmosphenoid moiety of the endocranium of _diplocercides kayseri_ (von koenen) showing the metapterygoid of the palatoquadrate loosely articulated to both the antotic and basipterygoid processes. according to tchernavin ( : ) and schaeffer and rosen ( : ) the swallowing of large prey depends on the ability of the fish to expand its oral cavity by allowing the posteroventral portion of the palatoquadrate and the posterior end of the mandible to swing outward. where the palatoquadrate articulates with the basisphenoid at the antotic and basipterygoid processes, as in the devonian coelacanths, it can not swing so far laterally as where it articulates with only the dorsal, antotic process. perhaps the loss of the basipterygoid articulation reflects the development of a more efficient mechanism for swallowing prey in these fishes. schaeffer and rosen ( : , ) show that in the evolution of the actinopterygians several changes improved the feeding mechanism: some of these changes are: ( ) freeing of the maxilla from the cheek, giving a larger chamber for the action of the adductor mandibulae; ( ) development of a coronoid process on the mandible; and ( ) increase in torque around the jaw articulation. in coelacanths, at least some comparable changes occurred, such as: ( ) loss of the maxillary, thus increasing the size of the adductor chamber; ( ) development of the coronoid bone, affording a greater area for muscle attachment; ( ) development of an arched dorsal margin on the angular; ( ) modification of the palatoquadrate complex, with resultant loss of the basipterygoid processes. in _synaptotylus_ the basipterygoid processes are small, not basally located, and perhaps not functional. a more efficient feeding mechanism developed rapidly during the carboniferous and has remained almost unaltered. [illustration: fig. . _synaptotylus newelli_ (hibbard). restoration of the parasphenoid, based on k. u. nos. , , × . a, ventral view, b, dorsal view and cross sections.] the parasphenoid (see fig. ) is a shovel-shaped bone having a wide anterior portion and a narrower posterior portion of nearly uniform width. most of the ventral surface is covered with minute granular teeth. the anterior margin is flared and curved posteromedially from the lateral margin to a median triangular projection. the lateral margins curve smoothly from the greatest anterior width to the narrow central portion, where the margins become somewhat thickened and turned dorsally. posterior to this the lateral margins are probably nearly straight. the external surface of the anterior section is nearly flat and has a central depressed area the sides of which slope evenly to the center. the internal surface is smooth and centrally convex. because of the fragmentary nature of all four observed specimens, total length was not measured but is estimated to be to mm. the opening of the hypophyseal canal was not present, possibly because of crushing. ethmoidal ossifications were not preserved in any of the specimens studied. the parasphenoid differs from that of _rhabdoderma elegans_ (newberry) in being more flared and widened anteriorly and more concave centrally. _dermal bones of the skull_ various portions of the cranial roof are preserved in several specimens (see fig. ). for comparisons with _rhabdoderma elegans_, see moy-thomas ( :fig. ). the premaxillaries and rostral elements are not preserved in any of the specimens. only one pair of relatively large frontals have been observed; they are . to . mm. long and . to . mm. wide. these are nearly flat bones, with the greatest width posteriorly . to . mm. wider than the anterior portion. the midline suture is straight, the lateral margins are nearly straight, the anterior margin slopes evenly posterolaterally, and the posterior margin is slightly convex to straight. the anterior margin in _r. elegans_ is essentially straight. ornamentation consists of sparse, unevenly spaced, coarse tubercles or short striae. in one specimen both bones have small clusters of tubercles near the lateral margins and about . mm. from the posterior margin. none of these bones has alisphenoids or ridges on the ventral surface, as stensiö ( : , ) described for _wimania_ and _axelia_. [illustration: fig. . _synaptotylus newelli_ (hibbard). diagram of the dermal bones of the skull, in lateral view, based on k. u. nos. and . × - / approximately.] only six supraorbitals have been preserved (see fig. ). these are nearly square, flat, thin bones lying nearly in place adjacent to a frontal on k. u. no. . the smallest is anterior; the margins of all are nearly straight. the bones are unornamented. each bears a pore of the supraorbital line just below the midline. the supraorbitals of _r. elegans_ have a triangular outline and do not bear pores. intertemporals (fig. ) on several specimens vary from approximately . to . mm. in length, . to . mm. in anterior width, and increase to . to . mm. in maximum posterior width. the midline suture is straight, the anterior margin is concave and the lateral margin proceeds laterally in a concave curve to the widest portion. in _r. elegans_ only the anterior half of the corresponding margin is concave. the posterior margin is slightly rounded and slopes anteriorly toward the lateral margin. ornamentation is usually of randomly oriented tubercles and striae, although striae are more common in the posterior third and may be longitudinal, whereas tubercles occur mainly on the anterior section. no evidence of sensory pores, as seen on the intertemporal of _r. elegans_, has been found. the supratemporals were observed on only one specimen (k. u. no. ), (fig. ). sutures were difficult to distinguish but the medial margin is presumed to curve to fit and to articulate with the lateral margins of the intertemporals. lateral margins are smoothly curved but the anterior and posterior margins were broken off. there appears to be no ornamentation on this bone. the supratemporals are much more elongated and curving than those in _r. elegans_. the cheek region is nearly complete in one specimen (k. u. no. ), and scattered parts occur in a few others (see fig. ). the lacrimojugal of no. is elongate, with both ends curving dorsally. it differs from the lacrimojugal in _r. elegans_, in which the anterior end extends anteriorly and is not curved dorsally. the posterior and anterior margins are not preserved; the greatest height appears to be posterior. pores of the suborbital portion of the infraorbital sensory canal are seen on the dorsal surface of the bone. in _r. elegans_ the pores are on the lateral surface. a section of the lacrimojugal on specimen no. , broken at both ends, shows a thin layer of bone perforated by the pores and covering a groove for the canal within the dorsal margin of the bone. both specimens are unornamented. a nearly complete postorbital (fig. ) on specimen no. is nearly triangular, with the apex ventral. the concave anterior margin bears pores of the postorbital part of the infraorbital line. ornamentation consists of widely spaced, coarse tubercles. part of one squamosal is preserved. it is somewhat triangular and its apex is ventral. this bone is associated with the postorbital, subopercular and lacrimojugal on no. . the preopercular sensory line passes down the curving ventral margin of this bone, and extends ventrally onto a narrow projection. a low ridge, nearly vertical, passes dorsally from about mid-point of the canal to the dorsal portion. the anterior margin is nearly straight, the ventral margin is concave, and the dorsal margin is convex dorsally but may be incomplete. perhaps the squamosal and preopercular are fused. the surface appears smooth; the view may be of the medial side. the squamosal of _r. elegans_ is nearly triangular and notably different from that of _synaptotylus newelli_. the subopercular (fig. ) shows closely spaced tubercles on the lateral surface. the bone is an elongated, irregular triangle with the apex pointing anterodorsally. the margins are incomplete, except for the concave, curving anterior margin. numerous operculars (fig. ) occur in the suite of specimens, both isolated and nearly in place. each is subtriangular; the apex of the triangle is ventral. a slight convexity projects from the anterodorsal border. the posterior margin is broadly but shallowly indented. otherwise the margins are smooth. maximum height ranges from . to . mm., and maximum width from . to . mm. ornamentation varies from a few widely spaced, randomly oriented tubercles to closely spaced tubercles merging posteriorly into striae. on some specimens these are parallel to the dorsal border, and oblique in the central portion. on the posterior margins of several operculars the striae break up into tubercles. a few operculars have closely spaced tubercles over much of the surface. the internal surface is smooth. _visceral skeleton_ the palatoquadrate complex, best seen on k. u. no. (fig. ), consists of endopterygoid, ectopterygoid, metapterygoid and quadrate. no trace of epipterygoids, dermopalatines or autopalatines, such as moy-thomas ( : , fig. ) described for _rhabdoderma_, has been observed. the endopterygoid has a long, ventral, anteriorly-directed process, and an anterodorsal process that meets the metapterygoid in forming the processus ascendens. the suture between the endopterygoid and metapterygoid, seen in lateral view, is distinct in some specimens and has an associated ridge; these bones appear to be fused in others, without regard to size. this suture curves dorsally from a point anterior to the quadrate and passes anterodorsally to the extremity of the processus ascendens. the suture is visible on the medial side only near the processus ascendens, for it is covered by a dorsal, toothed extension of the endopterygoid. the endopterygoid has a smooth lateral surface; the medial surface is covered with tiny granular teeth, in characteristic "line and dot" arrangement. the teeth extend onto the ventral surface of the ventral process. [illustration: fig. . _synaptotylus newelli_ (hibbard). restoration of the palatoquadrate complex, based on k. u. no. , × . a, medial view, b, lateral view.] two long, narrow, splintlike bones covered on one surface with granular teeth are interpreted as ectopterygoids. these are . and . mm. long and each is . mm. wide. orientation of these is unknown, but they probably fitted against the ventral surface of the ventral process of the endopterygoid (moy-thomas, :fig. ). [illustration: fig. . _synaptotylus newelli_ (hibbard). a, ceratohyal, lateral (?) view, based on k. u. nos. and , × . b, urohyal, based on k. u. no. , × .] the metapterygoid has a smooth surface in both views. the dorsal edge has a thickened, flared margin that presumably articulated with the antotic process of the basisphenoid. no articular surface for the basipterygoid process has been observed. the quadrate is distinct and closely applied to the posteroventral margin of the complex. in medial view the margin is nearly straight and continues to the ventral edge. the ventral surface is thickened and forms a rounded, knoblike articular surface. in lateral view the surface is smooth; the anterior margin is irregular (or perhaps broken on all specimens), and proceeds in an irregular convex curve from the posterior to the ventral margin. the general shape of the palatoquadrate complex is most nearly like that of _rhabdoderma elegans_ (moy-thomas, :fig. ). the orientation of the complex in the living fish was probably oblique, with the processus ascendens nearly vertical, the quadrate oblique, and the ventral process of the endopterygoid extending dorsoanteriorly and articulating with the parasphenoid. of the hyoid arch only the ceratohyals (see fig. a) are preserved in several specimens. these are long, curved bones with a posteroventral process and widened, flaring posterior margin. the medial (?) surface is concave in one specimen. the lateral (?) surface displays a distinct ridge on several specimens, arising on the dorsal surface opposite the posteroventral process and extending diagonally to the anteroventral end of the anterior limb. the impression of one other specimen appears to have a central ridge because of greater dorsal thickness and narrowness. both surfaces are unornamented. the urohyal (see fig. b) is an unornamented, y-shaped bone, with the stem of the y pointing anteriorly. orientation with respect to dorsal and ventral surfaces is uncertain. in one view a faint ridge, also y-shaped, occurs on the expanded posterior portion, and the surface is convex. the anterior process has a convex surface, sloping evenly off to the lateral margin; the opposite side of the process has a concave surface. the posterior portion has a slightly depressed area (see fig. b) at the junction of the "arms" of the y. the five branchial arches are represented by the ceratobranchials, several of which are preserved on k. u. no. . these are long bones with anteriorly curving ventral ends. the medial surfaces are partly covered with minute granular teeth; only the dorsal part is without teeth. the dorsal articular surface is convex dorsally and rounded. the mandible (fig. ), the best specimens of which are k. u. nos. and , is seen only in lateral and ventral views, with only angular, splenial and dentary visible. the angular forms the main body of the mandible, and is similar to that of _spermatodus_. the dorsal margin of the angular is expanded in the central region, with some variation. one specimen has an expanded portion slightly anterior to that of the opposite angular. the articular surface near the posterior end has not been observed; the posterior end of the angular slopes off abruptly. the anterior sutures are seen in only two specimens, k. u. nos. , . the dentary meets the angular in a long oblique suture; the dentary gradually tapers posterodorsally and ends on the dorsal surface of the angular. the splenial fits into a posteriorly directed, deep v-shaped notch on the ventral surface. the lateroventral surface of the angular contains sensory pores of the mandibular line. the ventral surface extends medially into a narrow shelf, approximately . mm. wide, which extends the full length of the bone; the external surface of this shelf is smooth and slightly concave dorsally. ornamentation of the angular consists of tubercles and longitudinal or oblique striae, occurring mostly on the expanded portion. the medial surface is not seen. several broken specimens show a central canal filled with a rod of calcite; in one of these the sensory pores are also calcite-filled and appear to be connected to the rod. thus the pores originally opened into a central canal. the dentary is an unornamented bone with the anterior half curving medially; the greatest height is anterior. this bone in specimen k. u. no. bears irregularly spaced, simple, recurved, conical teeth; nine were counted, but there is space for many others. one other specimen, no. , seems to have tiny tubercles on the surface. the dentary meets the splenial dorsally in a straight suture. the splenial also curves medially, and as stated, meets the dentary in a straight suture. ornamentation on this bone was not observed. the posterior margin is v-shaped and fits the notch in the angular. the ventral surface bears three or more sensory pores of the mandibular line. the gular plates are oval. the medial margin is straight to slightly curved, the lateral margin curved crescentically, the posterior end is blunt, and the anterior end somewhat rounded. ornamentation varies greatly; some bones show only a few tubercles, whereas others exhibit an almost concentric pattern of closely spaced striae. typically there are some tubercles in the anterior quarter or third of the total length; these pass into longitudinally oriented striae in the posterior section. a few have only randomly oriented, widely-spaced striae. the internal surface is smooth. the coronoid (k. u. no. ) is a triangular bone, with the apex pointing dorsally. the lateral surface is smooth; no teeth were observed. moy-thomas ( : , ) mentions several tooth-bearing coronoids in _rhabdoderma_, but as yet these have not been seen in _synaptotylus_. _axial skeleton_ only three specimens (k. u. nos. f, f, ) show parts of the vertebral column, but isolated neural and haemal arches are numerous. all are of the coelacanth type, having y-shaped neural and haemal arches, without centra. a total count of was obtained, but this was incomplete; the actual number was probably near . counts of and haemal arches were obtained in two of the specimens. total height of neural arches ranges from . to . mm., and of haemal arches, from . to . mm. the shorter arches are anterior and the height increases gradually to a maximum in the caudal region. height of the spines varies from . to . mm., or from twice the height of the arch in the anterior to three times the height in the caudal region. total width of the base, measured in isolated specimens because lateral views in other specimens prevented measuring width, ranges from . to . mm. the short, broad arches having short spines occur at the anterior end of the spinal column; the narrower arches having tall spines occur toward the caudal end. broken neural and haemal arches show a thin covering of bone with a central, calcite-filled cavity, which in life may have been filled with cartilage (stensiö, : , fig. ). no ossified ribs have been observed, either isolated or in place. for further description of the axial skeleton, see hibbard ( ). [illustration: fig. . _synaptotylus newelli_ (hibbard). paired fin girdles. a, pectoral girdle, lateral view, based on k. u. no. , × . . b, pelvic girdle basal plate, medial (?) view, based on k. u. no. , × . anterior is toward the left.] _girdles and paired fins_ a nearly complete pectoral girdle on specimen k. u. no. (see fig. a) has only a cleithrum and clavicle. no evidence of an extracleithrum or supracleithrum has been observed, but the extracleithrum may be fused to the cleithrum. the two bones form a boot-shaped unit, with the anteroventral part turned medially to form a horizontal process which meets the opposite half of the girdle. in lateral view the surface is unornamented, and convex in the ventral half. the suture between the cleithrum and clavicle begins on the expanded posterior portion, the "boot-heel," at a point immediately below the greatest width on the posterior margin, passes anteriorly, then turns sharply and parallels the anterior margin. the shape of the cleithrum resembles that in _rhabdoderma_ and the internal surface is not ridged (see moy-thomas, :fig. ). the exact orientation in the fish is uncertain, but if the median extension is really horizontal, then the posterior expansion is directed caudally. the medial surface is concave, steepest near the anterior margin, and then slopes outward evenly. in medial view one specimen (k. u. no. ) shows a small, caudally directed projection of bone, evidently for articulation of the fin-skeleton, at the widest portion of the cleithrum. sutures on several specimens were indistinct. broken specimens show sutural faces, but many nearly complete specimens show little or no indication of sutures, without regard to size of the girdles. the internal structure of the fin was not observed. numerous isolated basal plates of the pelvic girdle have revealed details of structure but no information on the orientation. presumably the basal plates of _synaptotylus_ had essentially the same orientation as those of other coelacanths (moy-thomas, : ). the most complete basal plate is k. u. no. (see fig. b). the three apophyses diverge anteriorly; the horizontal one is best developed and the dorsal one is least well developed. a median process (schaeffer, : ), denticulate on several specimens, articulates with the corresponding process of the opposite plate. the expanded part that articulates with the skeleton of the fin extends caudally. the posterior expanded part is nearly square in outline, resembling the dorsal, rectangular projection. one side bears ridges leading to the extremities of the apophyses, and faint crenulations on the median process. this may be the medial view. the other view displays a smooth surface, usually without indication of the ridges seen in the reverse view. these specimens differ somewhat from the basal plates of _rhabdoderma_ and appear to be intermediate between _rhabdoderma_ and _coelacanthus_ (moy-thomas, :fig. a, b). the apophyses are not free as in _rhabdoderma_ but webbed with bone almost to their extremities, as in _coelacanthus_. the pelvic fin is seen in only two specimens (k. u. nos. f, ). that on no. is lobate and has lepidotrichia, jointed for approximately the distal half, and . to . mm. in length. total length of the fin is . mm. there is no trace of the internal skeletal structure or of the articulation to the basal plate in either specimen. for a description of the fin on no. f, see hibbard ( : ). _unpaired fins_ a few isolated bones on k. u. no. (fig. ) are interpreted as basal plates of the unpaired fins. for additional description of the unpaired fins on the type, k. u. no. f, see hibbard ( ). two of these bones are flat, smooth and oblong, bearing a diagonal ridge that extends in the form of a projection. orientation is completely unknown. these may be basal plates of the anterior dorsal fin. the fin on no. f that hibbard ( : ) interpreted as the posterior dorsal fin is now thought to be the anterior dorsal fin. [illustration: fig. . _synaptotylus newelli_ (hibbard). basal plates of unpaired fins. a, anterior dorsal fin, based on k. u. no. , × . b, posterior dorsal fin, based on k. u. no. , × . c, anal fin, based on k. u. no. , × . anterior is toward the left.] one distinctive bone may represent the basal plate of the posterior dorsal fin. this incomplete specimen shows two projecting curved processes, bearing low but distinct ridges, which diverge, probably anteriorly. the central portion is narrow. the two ridges continue onto the posterior portion. this has been broken off, but shows that the ridges diverge again. the surface is smooth, except for the ridges. as before, orientation is uncertain. on no. f this fin was interpreted by hibbard ( : ) as the anal fin. only part of one basal plate of the anal fin was preserved on k. u. no. . that plate is oblong and has an expanded anterior end. the narrow, constricted part bears two oblique ridges and a few tubercles. the posterior part has nearly straight margins (represented by impressions) and the posterior margin is oblique, sloping anteroventrally. the flared anterior part has a smooth surface. this basal plate is more nearly like those of _coelacanthus_, according to the descriptions given by moy-thomas ( : ). the basal plate is associated with seven apparently unjointed, incomplete lepidotrichia. the anal fin on no. f is interpreted as the anterior dorsal fin (hibbard, : ). the caudal fins are preserved on k. u. nos. f, f, and have a total of lepidotrichia, above and below. these are jointed for the distal half or two-thirds, and are up to . mm. in length. in specimen no. f the supplementary caudal fin has at least seven lepidotrichia, the longest of which is . mm. but incomplete. anterior lepidotrichia appear unjointed but the posterior ones are jointed for the distal two-thirds (?) (these are broken off). the supplementary caudal fin is approximately . mm. long and . mm. or more wide. the supplementary caudal fin on k. u. no. f described by hibbard ( : ) could not be observed; this part of the caudal fin is missing. _squamation_ in the suite of specimens isolated scales are numerous, but patches of scales are rare. only two specimens (k. u. nos. f, f) are complete enough for scale counts, but preservation permits only partial counts. in general the scales resemble those of _rhabdoderma elegans_ (newberry). the scales are oval. the exposed posterior part of each bears posteriorly converging ridges; the anterior part is widest and shows a fine fibrillar structure. there are at least six scale-rows on either side of the lateral line. lateral line scales show no pores, and except for slight irregularities in the orientation and length of the posterior ridges, closely resemble the others. central ridges on the lateral line scales are shorter and tend to diverge from the center of the impression of the canal. the lateral line canal shows only as the impression of a continuous canal . mm. in diameter. preservation is poorest in scales along the line of the neural and haemal arches; therefore lateral line scales are rarely preserved. isolated scales are of two types: those on which the posterior ridges converge sharply and form the gothic arch configuration mentioned by hibbard ( : ), and those which do not. both types of scales can be present on one fish, as shown by specimen no. . this is not apparent on nos. f and f; all of the scales on these specimens appear to be much alike. both moy-thomas ( : ) and schaeffer ( : , ) have remarked on the variation of the scales on different parts of the same fish. because the number of ridges and amount of convergence of the ridges is not related to size of the scale, it is concluded that these characters are not of taxonomic significance. the strong resemblance of the scales of the garnett specimens to those of _rhabdoderma elegans_ (newberry) caused moy-thomas ( : ) to add hibbard's two species to the synonymy of _r. elegans_. but at that time only the scales could be adequately described. if the shape of the scale and the number and pattern of ridges can vary with age, size and shape of the scale, it follows that assignment of isolated scales to a species should not be attempted. assignment to genus should be made only with caution. _discussion._--the relationship of _synaptotylus_ to other coelacanths is obscure at present. the knoblike antotic processes on the basisphenoid are unlike those of any other known coelacanth. the palatoquadrate complex is shaped like that of _rhabdoderma elegans_ but consists of fewer bones, probably because of fusion. the scales resemble those of _rhabdoderma_. with regard to general shape of fin girdles, the pectoral girdle resembles that of _eusthenopteron_ more than that of _rhabdoderma_, but the cleithrum is more nearly like the cleithrum of _rhabdoderma_. the pelvic girdle appears to be midway between those of _rhabdoderma_ and _coelacanthus_ in general appearance. regarding the basal plates of the remaining fins, those of _synaptotylus_ appear to resemble basal plates of both _rhabdoderma_ and _coelacanthus_. considering the structure of the sphenethmoid region of the braincase, _synaptotylus_ is probably more closely related to _rhabdoderma_ than to other known coelacanth genera. comments on classifications classification of carboniferous coelacanths has been difficult, partly because the remains are commonly fragmentary, and significant changes in anatomy did not become apparent in early studies. in general, coelacanths have been remarkably stable in most characters, and it has been difficult to divide the group into families. as schaeffer ( : ) pointed out, definition of coelacanth genera and species has previously been made on non-meristic characters, and the range of variation within a species has received little attention. for example, reis ( : ) established the genus _rhabdoderma_, using the strong striation of the scales, gular plates and posterior mandible as the main characters of this carboniferous genus. moy-thomas ( : - ) referred all carboniferous species to _rhabdoderma_, redescribed the genus and compared it to _coelacanthus_, the permian genus. he cited as specific characters the ornamentation of the angulars, operculars and gular plates (moy-thomas, : ; : ). individual variation in some species has rendered ornamentation a poor criterion. this variation is apparent in _synaptotylus newelli_ (hibbard), some specimens having little or no ornamentation; others having much more. the number of ridges and pattern of ridges on the scales also varies. schaeffer ( : ) has found this to be true of _diplurus_ also. moy-thomas ( : ; : ) realized that the type of scale is a poor criterion for specific differentiation. in the search for features useful in distinguishing genera of coelacanths, schaeffer and gregory ( : , ) found the structure of the basisphenoid to be distinctive in known genera, and thought it had taxonomic significance at this level. higher categories should have as their basis characters that display evolutionary sequences. a recent classification (berg, ), followed in this paper, reflects two evolutionary trends in endocranial structure of coelacanths: reduction of endocranial ossification and loss of the basipterygoid processes. because there has been little change in other structures in coelacanths, berg's classification is the most useful. berg ( : ) includes _rhabdoderma_ in the suborder diplocercidoidei because of the presence of the basipterygoid processes, and in the single family, diplocercidae, but remarks that because of the reduced amount of endocranial ossification the carboniferous diplocercidae "probably constitute a distinct family." in considering this concept of classification, the subfamilies diplocercinae and rhabdodermatinae of the family diplocercidae are proposed above. the subfamily rhabdodermatinae includes at present _rhabdoderma_ and _synaptotylus_. the principal characters of the subfamily rhabdodermatinae, named for the first known genus, are the retention of the basipterygoid processes and the reduction of endocranial ossification. application of this classification based upon endocranial structure would probably change existing groupings of species of carboniferous coelacanths; the entire complex of carboniferous genera should be redescribed and redefined. it will be necessary to consider endocranial structure in any future classification. the greater part of the evolution previously mentioned appears to have been accomplished during the carboniferous; thereafter coelacanth structure became stabilized. the trend progressed from devonian coelacanths which had two large unpaired bones in the endocranium, and both antotic and basipterygoid processes on the basisphenoid, to carboniferous fishes in which ossification was reduced to a number of paired and unpaired bones embedded in cartilage, and retaining both processes, and then post-carboniferous kinds with reduced ossification and no basipterygoid processes. the pennsylvanian was evidently the time of greatest change for the coelacanths, and they have not changed significantly since, in spite of the fact that since the jurassic they have shifted their environment from shallow, fresh water to moderate depth in the sea (schaeffer, :fig. ). the changes in endocranial structure appear to be significant, and are perhaps related to higher efficiency of the mouth parts in catching and swallowing prey (see p. ). environment the coelacanth fishes from the rock lake shale are part of the varied fauna collected from garnett. peabody ( : ) listed many elements of the fauna and flora, and concluded that the deposits are of lagoonal origin. in addition to numerous invertebrates (including microfossils) and arthropods, a number of vertebrates other than coelacanths have been found. these include at least one kind of shark, _hesperoherpeton garnettense_ peabody, one or more kinds of undescribed labyrinthodonts and the reptiles _petrolacosaurus kansensis_ lane, _edaphosaurus ecordi_ peabody, and _clepsydrops_ (undescribed species). this is indeed a rich vertebrate fauna, and the earliest known reptilian fauna. much of the rock contains plant remains. the flora that has been identified is adapted to growing in a well-drained soil; although it contains some elements considered characteristic of the permian, it is of pennsylvanian age (moore _et al._, ). peabody ( : - ) discusses the features of these lagoonal sediments. much of the fauna and flora suggests continental origin, but the many marine invertebrates at some horizons indicate that at least some of the sediments were of marine origin. little can be said about the actual environment of the living fishes of the genus _synaptotylus_. remains of these fishes occur in layers containing marine invertebrates, as well as in those containing plant remains and vertebrate skeletal parts, and in those nearly completely composed of dark carbonaceous material. most of the remains are fragmentary and consist of isolated bones, isolated scales, and dissociated skulls; only one specimen and half of another are nearly complete. many published statements on _rhabdoderma_, a related genus, indicate both marine and fresh-water environments. wehrli ( : ) regarded _rhabdoderma elegans_ (newberry) as a euryhaline species, and cited its occurrence with both marine and fresh-water fossils. aldinger ( : ) also found this to be the case with other species, and fiege ( : ) quotes others as giving the same information. keller ( : ) thought that few carboniferous fishes were exclusively marine, and stated that the majority of them became adapted to fresh water during the late carboniferous. later, schaeffer ( : ) stated that all carboniferous and permian coelacanths were fresh-water fishes, and that many were from swamp deposits. if keller is correct, then members of the genus _synaptotylus_ may have inhabited the lagoon, the adjacent sea, or the streams draining into the lagoon. perhaps these fishes swam upstream, as modern salmon and tarpon do, although there is no direct evidence for this. possibly they lived in the lagoon at times of scant rainfall and little runoff, when the salinity of lagoon water approached normal marine values or the fishes may have lived in the streams, and after death were washed into the lagoon. as numerous remains of land plants and animals were washed in, perhaps this best accounts for the presence of the fish in nearly all layers of the deposits, not only the marine strata. summary a new genus of pennsylvanian coelacanths, _synaptotylus_, is described and a previously named species, _coelacanthus newelli_ hibbard, (_c. arcuatus_ hibbard, , is a junior synonym), is referred to this genus. all specimens of _synaptotylus newelli_ (hibbard) were collected from the rock lake shale member of the stanton formation, lansing group, missouri series, six miles northwest of garnett, anderson county, kansas. _synaptotylus_ is distinguished from all other coelacanths by a basisphenoid having large, knoblike antotic processes each connected by a low ridge to a small basipterygoid process. _synaptotylus_ is most closely related to _rhabdoderma_, but is intermediate between _rhabdoderma_ and _coelacanthus_ in shape of the fin girdles and basal plates. two new subfamilies, diplocercinae and rhabdodermatinae, of the family diplocercidae, are proposed. _synaptotylus_ and _rhabdoderma_ are included in the subfamily rhabdodermatinae, because both exhibit reduced ossification in the endocranium and retain basipterygoid processes. loss of the basipterygoid processes in post-carboniferous coelacanths may reflect the development of a more efficient feeding mechanism, by allowing the palatoquadrate complex and mandible to swing farther laterally and expand the oral cavity. _synaptotylus newelli_ (hibbard) may have occupied either the sea or fresh water; these fishes occur in lagoonal deposits with reptiles and amphibians, arthropods, marine invertebrates and remains of land plants. because scale patterns on _synaptotylus_ and _rhabdoderma_ are so nearly similar and vary with size of the scale and its location on the fish, it is recommended that isolated scales not be assigned to a species, and to a genus only with great caution. literature cited aldinger, h. . ueber karbonische fische aus westfälen. paleont. zeit., : - . berg, l. s. . classification of fishes, both recent and fossil. moscow and leningrad, (j. w. edwards, ann arbor, michigan, , offset reproduction, pp. - , figs., plus english translation of text, pp. - , .) fiege, k. . eine fisch-schwimmspur aus dem culm bei waldeck. neues jahrb. geol. and paläont. jahrgang : - . hibbard, c. w. . two new species of _coelacanthus_ from the middle pennsylvanian of anderson county, kansas. kansas univ. sci. bull., : - . keller, g. . fischreste aus dem oberkarbon des ruhrgebiets. gluckauf, : - . moore, r. c., elias, m. k., and newell, n. d. . a "permian" flora from the pennsylvanian rocks of kansas. jour. geol., : - . moy-thomas, j. a. . a synopsis of the coelacanth fishes of the yorkshire coal measures. ann. mag. nat. hist., (ser. ): - . . the carboniferous coelacanth fishes of great britain and ireland. proc. zool. soc. london, (b): - . peabody, f. e. . _petrolacosaurus kansensis_ lane, a pennsylvanian reptile from kansas. kansas univ. paleont. contrib., : - . reis, o. m. . die coelacanthinen mit besonderen berücksichtigung der im weissen jura bayerns verkommenden arten. palaeontographica, : - . schaeffer, b. . the triassic coelacanth fish _diplurus_, with observations on the evolution of the coelacanthini. bull. amer. mus. nat. hist., :art. , - . . _latimeria_ and the history of the coelacanth fishes. new york acad. sci. trans., ( ) : - . schaeffer, b., and gregory, j. t. . coelacanth fishes from the continental triassic of the western united states. amer. mus. novitates, : - . schaeffer, b., and rosen, d. e. . major adaptive levels in the evolution of the actinopterygian feeding mechanism. am. zool., : - . smith, j. l. b. . a living coelacanthid fish from south africa. trans. roy. soc. south africa, : - . stensiÖ, e. a. . triassic fishes from spitzbergen. part i. vienna, adolf holzhausen: - . . triassic fishes from east greenland. meddel. om grønland, : - . tchernavin, v. v. . on the mechanical working of the head of bony fishes. proc. zool. soc. london, : - . wehrli, h. . die fauna der westfälischen stufen a und b der bochumer mulde zwischen dortmund und kamen (westfälen). palaeontographica, : - . _transmitted march , ._ the method by which the causes of the present and past conditions of organic nature are to be discovered.--the origination of living beings lecture iii. (of vi.), lectures to working men, at the museum of practical geology, , on darwin's work: "origin of species". by thomas h. huxley in the two preceding lectures i have endeavoured to indicate to you the extent of the subject-matter of the inquiry upon which we are engaged; and now, having thus acquired some conception of the past and present phenomena of organic nature, i must now turn to that which constitutes the great problem which we have set before ourselves;--i mean, the question of what knowledge we have of the causes of these phenomena of organic nature, and how such knowledge is obtainable. here, on the threshold of the inquiry, an objection meets us. there are in the world a number of extremely worthy, well-meaning persons, whose judgments and opinions are entitled to the utmost respect on account of their sincerity, who are of opinion that vital phenomena, and especially all questions relating to the origin of vital phenomena, are questions quite apart from the ordinary run of inquiry, and are, by their very nature, placed out of our reach. they say that all these phenomena originated miraculously, or in some way totally different from the ordinary course of nature, and that therefore they conceive it to be futile, not to say presumptuous, to attempt to inquire into them. to such sincere and earnest persons, i would only say, that a question of this kind is not to be shelved upon theoretical or speculative grounds. you may remember the story of the sophist who demonstrated to diogenes in the most complete and satisfactory manner that he could not walk; that, in fact, all motion was an impossibility; and that diogenes refuted him by simply getting up and walking round his tub. so, in the same way, the man of science replies to objections of this kind, by simply getting up and walking onward, and showing what science has done and is doing--by pointing to that immense mass of facts which have been ascertained and systematized under the forms of the great doctrines of morphology, of development, of distribution, and the like. he sees an enormous mass of facts and laws relating to organic beings, which stand on the same good sound foundation as every other natural law; and therefore, with this mass of facts and laws before us, therefore, seeing that, as far as organic matters have hitherto been accessible and studied, they have shown themselves capable of yielding to scientific investigation, we may accept this as proof that order and law reign there as well as in the rest of nature; and the man of science says nothing to objectors of this sort, but supposes that we can and shall walk to a knowledge of the origin of organic nature, in the same way that we have walked to a knowledge of the laws and principles of the inorganic world. but there are objectors who say the same from ignorance and ill-will. to such i would reply that the objection comes ill from them, and that the real presumption, i may almost say the real blasphemy, in this matter, is in the attempt to limit that inquiry into the causes of phenomena which is the source of all human blessings, and from which has sprung all human prosperity and progress; for, after all, we can accomplish comparatively little; the limited range of our own faculties bounds us on every side,--the field of our powers of observation is small enough, and he who endeavours to narrow the sphere of our inquiries is only pursuing a course that is likely to produce the greatest harm to his fellow-men. but now, assuming, as we all do, i hope, that these phenomena are properly accessible to inquiry, and setting out upon our search into the causes of the phenomena of organic nature, or, at any rate, setting out to discover how much we at present know upon these abstruse matters, the question arises as to what is to be our course of proceeding, and what method we must lay down for our guidance. i reply to that question, that our method must be exactly the same as that which is pursued in any other scientific inquiry, the method of scientific investigation being the same for all orders of facts and phenomena whatsoever. i must dwell a little on this point, for i wish you to leave this room with a very clear conviction that scientific investigation is not, as many people seem to suppose, some kind of modern black art. i say that you might easily gather this impression from the manner in which many persons speak of scientific inquiry, or talk about inductive and deductive philosophy, or the principles of the "baconian philosophy." i do protest that, of the vast number of cants in this world, there are none, to my mind, so contemptible as the pseudoscientific cant which is talked about the "baconian philosophy." to hear people talk about the great chancellor--and a very great man he certainly was,--you would think that it was he who had invented science, and that there was no such thing as sound reasoning before the time of queen elizabeth. of course you say, that cannot possibly be true; you perceive, on a moment's reflection, that such an idea is absurdly wrong, and yet, so firmly rooted is this sort of impression,--i cannot call it an idea, or conception,--the thing is too absurd to be entertained,--but so completely does it exist at the bottom of most men's minds, that this has been a matter of observation with me for many years past. there are many men who, though knowing absolutely nothing of the subject with which they may be dealing, wish, nevertheless, to damage the author of some view with which they think fit to disagree. what they do, then, is not to go and learn something about the subject, which one would naturally think the best way of fairly dealing with it; but they abuse the originator of the view they question, in a general manner, and wind up by saying that, "after all, you know, the principles and method of this author are totally opposed to the canons of the baconian philosophy." then everybody applauds, as a matter of course, and agrees that it must be so. but if you were to stop them all in the middle of their applause, you would probably find that neither the speaker nor his applauders could tell you how or in what way it was so; neither the one nor the other having the slightest idea of what they mean when they speak of the "baconian philosophy." you will understand, i hope, that i have not the slightest desire to join in the outcry against either the morals, the intellect, or the great genius of lord chancellor bacon. he was undoubtedly a very great man, let people say what they will of him; but notwithstanding all that he did for philosophy, it would be entirely wrong to suppose that the methods of modern scientific inquiry originated with him, or with his age; they originated with the first man, whoever he was; and indeed existed long before him, for many of the essential processes of reasoning are exerted by the higher order of brutes as completely and effectively as by ourselves. we see in many of the brute creation the exercise of one, at least, of the same powers of reasoning as that which we ourselves employ. the method of scientific investigation is nothing but the expression of the necessary mode of working of the human mind. it is simply the mode at which all phenomena are reasoned about, rendered precise and exact. there is no more difference, but there is just the same kind of difference, between the mental operations of a man of science and those of an ordinary person, as there is between the operations and methods of a baker or of a butcher weighing out his goods in common scales, and the operations of a chemist in performing a difficult and complex analysis by means of his balance and finely-graduated weights. it is not that the action of the scales in the one case, and the balance in the other, differ in the principles of their construction or manner of working; but the beam of one is set on an infinitely finer axis than the other, and of course turns by the addition of a much smaller weight. you will understand this better, perhaps, if i give you some familiar example. you have all heard it repeated, i dare say, that men of science work by means of induction and deduction, and that by the help of these operations, they, in a sort of sense, wring from nature certain other things, which are called natural laws, and causes, and that out of these, by some cunning skill of their own, they build up hypotheses and theories. and it is imagined by many, that the operations of the common mind can be by no means compared with these processes, and that they have to be acquired by a sort of special apprenticeship to the craft. to hear all these large words, you would think that the mind of a man of science must be constituted differently from that of his fellow men; but if you will not be frightened by terms, you will discover that you are quite wrong, and that all these terrible apparatus are being used by yourselves every day and every hour of your lives. there is a well-known incident in one of moliere's plays, where the author makes the hero express unbounded delight on being told that he had been talking prose during the whole of his life. in the same way, i trust, that you will take comfort, and be delighted with yourselves, on the discovery that you have been acting on the principles of inductive and deductive philosophy during the same period. probably there is not one here who has not in the course of the day had occasion to set in motion a complex train of reasoning, of the very same kind, though differing of course in degree, as that which a scientific man goes through in tracing the causes of natural phenomena. a very trivial circumstance will serve to exemplify this. suppose you go into a fruiterer's shop, wanting an apple,--you take up one, and, on biting it, you find it is sour; you look at it, and see that it is hard and green. you take up another one, and that too is hard, green, and sour. the shopman offers you a third; but, before biting it, you examine it, and find that it is hard and green, and you immediately say that you will not have it, as it must be sour, like those that you have already tried. nothing can be more simple than that, you think; but if you will take the trouble to analyze and trace out into its logical elements what has been done by the mind, you will be greatly surprised. in the first place, you have performed the operation of induction. you found that, in two experiences, hardness and greenness in apples go together with sourness. it was so in the first case, and it was confirmed by the second. true, it is a very small basis, but still it is enough to make an induction from; you generalize the facts, and you expect to find sourness in apples where you get hardness and greenness. you found upon that a general law, that all hard and green apples are sour; and that, so far as it goes, is a perfect induction. well, having got your natural law in this way, when you are offered another apple which you find is hard and green, you say, "all hard and green apples are sour; this apple is hard and green, therefore this apple is sour." that train of reasoning is what logicians call a syllogism, and has all its various parts and terms,--its major premiss, its minor premiss, and its conclusion. and, by the help of further reasoning, which, if drawn out, would have to be exhibited in two or three other syllogisms, you arrive at your final determination, "i will not have that apple." so that, you see, you have, in the first place, established a law by induction, and upon that you have founded a deduction, and reasoned out the special conclusion of the particular case. well now, suppose, having got your law, that at some time afterwards, you are discussing the qualities of apples with a friend: you will say to him, "it is a very curious thing,--but i find that all hard and green apples are sour!" your friend says to you, "but how do you know that?" you at once reply, "oh, because i have tried it over and over again, and have always found them to be so." well, if we were talking science instead of common sense, we should call that an experimental verification. and, if still opposed, you go further, and say, "i have heard from the people in somersetshire and devonshire, where a large number of apples are grown, that they have observed the same thing. it is also found to be the case in normandy, and in north america. in short, i find it to be the universal experience of mankind wherever attention has been directed to the subject." whereupon, your friend, unless he is a very unreasonable man, agrees with you, and is convinced that you are quite right in the conclusion you have drawn. he believes, although perhaps he does not know he believes it, that the more extensive verifications are,--that the more frequently experiments have been made, and results of the same kind arrived at,--that the more varied the conditions under which the same results have been attained, the more certain is the ultimate conclusion, and he disputes the question no further. he sees that the experiment has been tried under all sorts of conditions, as to time, place, and people, with the same result; and he says with you, therefore, that the law you have laid down must be a good one, and he must believe it. in science we do the same thing;--the philosopher exercises precisely the same faculties, though in a much more delicate manner. in scientific inquiry it becomes a matter of duty to expose a supposed law to every possible kind of verification, and to take care, moreover, that this is done intentionally, and not left to a mere accident, as in the case of the apples. and in science, as in common life, our confidence in a law is in exact proportion to the absence of variation in the result of our experimental verifications. for instance, if you let go your grasp of an article you may have in your hand, it will immediately fall to the ground. that is a very common verification of one of the best established laws of nature--that of gravitation. the method by which men of science establish the existence of that law is exactly the same as that by which we have established the trivial proposition about the sourness of hard and green apples. but we believe it in such an extensive, thorough, and unhesitating manner because the universal experience of mankind verifies it, and we can verify it ourselves at any time; and that is the strongest possible foundation on which any natural law can rest. so much by way of proof that the method of establishing laws in science is exactly the same as that pursued in common life. let us now turn to another matter (though really it is but another phase of the same question), and that is, the method by which, from the relations of certain phenomena, we prove that some stand in the position of causes towards the others. i want to put the case clearly before you, and i will therefore show you what i mean by another familiar example. i will suppose that one of you, on coming down in the morning to the parlour of your house, finds that a tea-pot and some spoons which had been left in the room on the previous evening are gone,--the window is open, and you observe the mark of a dirty hand on the window-frame, and perhaps, in addition to that, you notice the impress of a hob-nailed shoe on the gravel outside. all these phenomena have struck your attention instantly, and before two minutes have passed you say, "oh, somebody has broken open the window, entered the room, and run off with the spoons and the tea-pot!" that speech is out of your mouth in a moment. and you will probably add, "i know there has; i am quite sure of it!" you mean to say exactly what you know; but in reality what you have said has been the expression of what is, in all essential particulars, an hypothesis. you do not 'know' it at all; it is nothing but an hypothesis rapidly framed in your own mind! and it is an hypothesis founded on a long train of inductions and deductions. what are those inductions and deductions, and how have you got at this hypothesis? you have observed, in the first place, that the window is open; but by a train of reasoning involving many inductions and deductions, you have probably arrived long before at the general law--and a very good one it is--that windows do not open of themselves; and you therefore conclude that something has opened the window. a second general law that you have arrived at in the same way is, that tea-pots and spoons do not go out of a window spontaneously, and you are satisfied that, as they are not now where you left them, they have been removed. in the third place, you look at the marks on the window-sill, and the shoemarks outside, and you say that in all previous experience the former kind of mark has never been produced by anything else but the hand of a human being; and the same experience shows that no other animal but man at present wears shoes with hob-nails on them such as would produce the marks in the gravel. i do not know, even if we could discover any of those "missing links" that are talked about, that they would help us to any other conclusion! at any rate the law which states our present experience is strong enough for my present purpose.--you next reach the conclusion, that as these kinds of marks have not been left by any other animals than men, or are liable to be formed in any other way than by a man's hand and shoe, the marks in question have been formed by a man in that way. you have, further, a general law, founded on observation and experience, and that, too, is, i am sorry to say, a very universal and unimpeachable one,--that some men are thieves; and you assume at once from all these premisses--and that is what constitutes your hypothesis--that the man who made the marks outside and on the window-sill, opened the window, got into the room, and stole your tea-pot and spoons. you have now arrived at a 'vera causa';--you have assumed a cause which it is plain is competent to produce all the phenomena you have observed. you can explain all these phenomena only by the hypothesis of a thief. but that is a hypothetical conclusion, of the justice of which you have no absolute proof at all; it is only rendered highly probable by a series of inductive and deductive reasonings. i suppose your first action, assuming that you are a man of ordinary common sense, and that you have established this hypothesis to your own satisfaction, will very likely be to go off for the police, and set them on the track of the burglar, with the view to the recovery of your property. but just as you are starting with this object, some person comes in, and on learning what you are about, says, "my good friend, you are going on a great deal too fast. how do you know that the man who really made the marks took the spoons? it might have been a monkey that took them, and the man may have merely looked in afterwards." you would probably reply, "well, that is all very well, but you see it is contrary to all experience of the way tea-pots and spoons are abstracted; so that, at any rate, your hypothesis is less probable than mine." while you are talking the thing over in this way, another friend arrives, one of that good kind of people that i was talking of a little while ago. and he might say, "oh, my dear sir, you are certainly going on a great deal too fast. you are most presumptuous. you admit that all these occurrences took place when you were fast asleep, at a time when you could not possibly have known anything about what was taking place. how do you know that the laws of nature are not suspended during the night? it may be that there has been some kind of supernatural interference in this case." in point of fact, he declares that your hypothesis is one of which you cannot at all demonstrate the truth, and that you are by no means sure that the laws of nature are the same when you are asleep as when you are awake. well, now, you cannot at the moment answer that kind of reasoning. you feel that your worthy friend has you somewhat at a disadvantage. you will feel perfectly convinced in your own mind, however, that you are quite right, and you say to him, "my good friend, i can only be guided by the natural probabilities of the case, and if you will be kind enough to stand aside and permit me to pass, i will go and fetch the police." well, we will suppose that your journey is successful, and that by good luck you meet with a policeman; that eventually the burglar is found with your property on his person, and the marks correspond to his hand and to his boots. probably any jury would consider those facts a very good experimental verification of your hypothesis, touching the cause of the abnormal phenomena observed in your parlour, and would act accordingly. now, in this suppositious case, i have taken phenomena of a very common kind, in order that you might see what are the different steps in an ordinary process of reasoning, if you will only take the trouble to analyse it carefully. all the operations i have described, you will see, are involved in the mind of any man of sense in leading him to a conclusion as to the course he should take in order to make good a robbery and punish the offender. i say that you are led, in that case, to your conclusion by exactly the same train of reasoning as that which a man of science pursues when he is endeavouring to discover the origin and laws of the most occult phenomena. the process is, and always must be, the same; and precisely the same mode of reasoning was employed by newton and laplace in their endeavours to discover and define the causes of the movements of the heavenly bodies, as you, with your own common sense, would employ to detect a burglar. the only difference is, that the nature of the inquiry being more abstruse, every step has to be most carefully watched, so that there may not be a single crack or flaw in your hypothesis. a flaw or crack in many of the hypotheses of daily life may be of little or no moment as affecting the general correctness of the conclusions at which we may arrive; but, in a scientific inquiry, a fallacy, great or small, is always of importance, and is sure to be constantly productive of mischievous, if not fatal results. do not allow yourselves to be misled by the common notion that an hypothesis is untrustworthy simply because it is an hypothesis. it is often urged, in respect to some scientific conclusion, that, after all, it is only an hypothesis. but what more have we to guide us in nine-tenths of the most important affairs of daily life than hypotheses, and often very ill-based ones? so that in science, where the evidence of an hypothesis is subjected to the most rigid examination, we may rightly pursue the same course. you may have hypotheses and hypotheses. a man may say, if he likes, that the moon is made of green cheese: that is an hypothesis. but another man, who has devoted a great deal of time and attention to the subject, and availed himself of the most powerful telescopes and the results of the observations of others, declares that in his opinion it is probably composed of materials very similar to those of which our own earth is made up: and that is also only an hypothesis. but i need not tell you that there is an enormous difference in the value of the two hypotheses. that one which is based on sound scientific knowledge is sure to have a corresponding value; and that which is a mere hasty random guess is likely to have but little value. every great step in our progress in discovering causes has been made in exactly the same way as that which i have detailed to you. a person observing the occurrence of certain facts and phenomena asks, naturally enough, what process, what kind of operation known to occur in nature applied to the particular case, will unravel and explain the mystery? hence you have the scientific hypothesis; and its value will be proportionate to the care and completeness with which its basis had been tested and verified. it is in these matters as in the commonest affairs of practical life: the guess of the fool will be folly, while the guess of the wise man will contain wisdom. in all cases, you see that the value of the result depends on the patience and faithfulness with which the investigator applies to his hypothesis every possible kind of verification. i dare say i may have to return to this point by-and-by; but having dealt thus far with our logical methods, i must now turn to something which, perhaps, you may consider more interesting, or, at any rate, more tangible. but in reality there are but few things that can be more important for you to understand than the mental processes and the means by which we obtain scientific conclusions and theories. [ ] having granted that the inquiry is a proper one, and having determined on the nature of the methods we are to pursue and which only can lead to success, i must now turn to the consideration of our knowledge of the nature of the processes which have resulted in the present condition of organic nature. here, let me say at once, lest some of you misunderstand me, that i have extremely little to report. the question of how the present condition of organic nature came about, resolves itself into two questions. the first is: how has organic or living matter commenced its existence? and the second is: how has it been perpetuated? on the second question i shall have more to say hereafter. but on the first one, what i now have to say will be for the most part of a negative character. if you consider what kind of evidence we can have upon this matter, it will resolve itself into two kinds. we may have historical evidence and we may have experimental evidence. it is, for example, conceivable, that inasmuch as the hardened mud which forms a considerable portion of the thickness of the earth's crust contains faithful records of the past forms of life, and inasmuch as these differ more and more as we go further down,--it is possible and conceivable that we might come to some particular bed or stratum which should contain the remains of those creatures with which organic life began upon the earth. and if we did so, and if such forms of organic life were preservable, we should have what i would call historical evidence of the mode in which organic life began upon this planet. many persons will tell you, and indeed you will find it stated in many works on geology, that this has been done, and that we really possess such a record; there are some who imagine that the earliest forms of life of which we have as yet discovered any record, are in truth the forms in which animal life began upon the globe. the grounds on which they base that supposition are these:--that if you go through the enormous thickness of the earth's crust and get down to the older rocks, the higher vertebrate animals--the quadrupeds, birds, and fishes--cease to be found; beneath them you find only the invertebrate animals; and in the deepest and lowest rocks those remains become scantier and scantier, not in any very gradual progression, however, until, at length, in what are supposed to be the oldest rocks, the animal remains which are found are almost always confined to four forms--'oldhamia', whose precise nature is not known, whether plant or animal; 'lingula', a kind of mollusc; 'trilobites', a crustacean animal, having the same essential plan of construction, though differing in many details from a lobster or crab; and hymenocaris, which is also a crustacean. so that you have all the 'fauna' reduced, at this period, to four forms: one a kind of animal or plant that we know nothing about, and three undoubted animals--two crustaceans and one mollusc. i think, considering the organization of these mollusca and crustacea, and looking at their very complex nature, that it does indeed require a very strong imagination to conceive that these were the first created of all living things. and you must take into consideration the fact that we have not the slightest proof that these which we call the oldest beds are really so: i repeat, we have not the slightest proof of it. when you find in some places that in an enormous thickness of rocks there are but very scanty traces of life, or absolutely none at all; and that in other parts of the world rocks of the very same formation are crowded with the records of living forms, i think it is impossible to place any reliance on the supposition, or to feel oneself justified in supposing that these are the forms in which life first commenced. i have not time here to enter upon the technical grounds upon which i am led to this conclusion,--that could hardly be done properly in half a dozen lectures on that part alone;--i must content myself with saying that i do not at all believe that these are the oldest forms of life. i turn to the experimental side to see what evidence we have there. to enable us to say that we know anything about the experimental origination of organization and life, the investigator ought to be able to take inorganic matters, such as carbonic acid, ammonia, water, and salines, in any sort of inorganic combination, and be able to build them up into protein matter, and that that protein matter ought to begin to live in an organic form. that, nobody has done as yet, and i suspect it will be a long while before anybody does do it. but the thing is by no means so impossible as it looks; for the researches of modern chemistry have shown us--i won't say the road towards it, but, if i may so say, they have shown the finger-post pointing to the road that may lead to it. it is not many years ago--and you must recollect that organic chemistry is a young science, not above a couple of generations old,--you must not expect too much of it; it is not many years ago since it was said to be perfectly impossible to fabricate any organic compound; that is to say, any non-mineral compound which is to be found in an organized being. it remained so for a very long period; but it is now a considerable number of years since a distinguished foreign chemist contrived to fabricate urea, a substance of a very complex character, which forms one of the waste products of animal structures. and of late years a number of other compounds, such as butyric acid, and others, have been added to the list. i need not tell you that chemistry is an enormous distance from the goal i indicate; all i wish to point out to you is, that it is by no means safe to say that that goal may not be reached one day. it may be that it is impossible for us to produce the conditions requisite to the origination of life; but we must speak modestly about the matter, and recollect that science has put her foot upon the bottom round of the ladder. truly he would be a bold man who would venture to predict where she will be fifty years hence. there is another inquiry which bears indirectly upon this question, and upon which i must say a few words. you are all of you aware of the phenomena of what is called spontaneous generation. our forefathers, down to the seventeenth century, or thereabouts, all imagined, in perfectly good faith, that certain vegetable and animal forms gave birth, in the process of their decomposition, to insect life. thus, if you put a piece of meat in the sun, and allowed it to putrefy, they conceived that the grubs which soon began to appear were the result of the action of a power of spontaneous generation which the meat contained. and they could give you receipts for making various animal and vegetable preparations which would produce particular kinds of animals. a very distinguished italian naturalist, named redi, took up the question, at a time when everybody believed in it; among others our own great harvey, the discoverer of the circulation of the blood. you will constantly find his name quoted, however, as an opponent of the doctrine of spontaneous generation; but the fact is, and you will see it if you will take the trouble to look into his works, harvey believed it as profoundly as any man of his time; but he happened to enunciate a very curious proposition--that every living thing came from an 'egg'; he did not mean to use the word in the sense in which we now employ it, he only meant to say that every living thing originated in a little rounded particle of organized substance; and it is from this circumstance, probably, that the notion of harvey having opposed the doctrine originated. then came redi, and he proceeded to upset the doctrine in a very simple manner. he merely covered the piece of meat with some very fine gauze, and then he exposed it to the same conditions. the result of this was that no grubs or insects were produced; he proved that the grubs originated from the insects who came and deposited their eggs in the meat, and that they were hatched by the heat of the sun. by this kind of inquiry he thoroughly upset the doctrine of spontaneous generation, for his time at least. then came the discovery and application of the microscope to scientific inquiries, which showed to naturalists that besides the organisms which they already knew as living beings and plants, there were an immense number of minute things which could be obtained apparently almost at will from decaying vegetable and animal forms. thus, if you took some ordinary black pepper or some hay, and steeped it in water, you would find in the course of a few days that the water had become impregnated with an immense number of animalcules swimming about in all directions. from facts of this kind naturalists were led to revive the theory of spontaneous generation. they were headed here by an english naturalist,--needham,--and afterwards in france by the learned buffon. they said that these things were absolutely begotten in the water of the decaying substances out of which the infusion was made. it did not matter whether you took animal or vegetable matter, you had only to steep it in water and expose it, and you would soon have plenty of animalcules. they made an hypothesis about this which was a very fair one. they said, this matter of the animal world, or of the higher plants, appears to be dead, but in reality it has a sort of dim life about it, which, if it is placed under fair conditions, will cause it to break up into the forms of these little animalcules, and they will go through their lives in the same way as the animal or plant of which they once formed a part. the question now became very hotly debated. spallanzani, an italian naturalist, took up opposite views to those of needham and buffon, and by means of certain experiments he showed that it was quite possible to stop the process by boiling the water, and closing the vessel in which it was contained. "oh!" said his opponents; "but what do you know you may be doing when you heat the air over the water in this way? you may be destroying some property of the air requisite for the spontaneous generation of the animalcules." however, spallanzani's views were supposed to be upon the right side, and those of the others fell into discredit; although the fact was that spallanzani had not made good his views. well, then, the subject continued to be revived from time to time, and experiments were made by several persons; but these experiments were not altogether satisfactory. it was found that if you put an infusion in which animalcules would appear if it were exposed to the air into a vessel and boiled it, and then sealed up the mouth of the vessel, so that no air, save such as had been heated to degrees, could reach its contents, that then no animalcules would be found; but if you took the same vessel and exposed the infusion to the air, then you would get animalcules. furthermore, it was found that if you connected the mouth of the vessel with a red-hot tube in such a way that the air would have to pass through the tube before reaching the infusion, that then you would get no animalcules. yet another thing was noticed: if you took two flasks containing the same kind of infusion, and left one entirely exposed to the air, and in the mouth of the other placed a ball of cotton wool, so that the air would have to filter itself through it before reaching the infusion, that then, although you might have plenty of animalcules in the first flask, you would certainly obtain none from the second. these experiments, you see, all tended towards one conclusion--that the infusoria were developed from little minute spores or eggs which were constantly floating in the atmosphere, which lose their power of germination if subjected to heat. but one observer now made another experiment which seemed to go entirely the other way, and puzzled him altogether. he took some of this boiled infusion that i have been speaking of, and by the use of a mercurial bath--a kind of trough used in laboratories--he deftly inverted a vessel containing the infusion into the mercury, so that the latter reached a little beyond the level of the mouth of the 'inverted' vessel. you see that he thus had a quantity of the infusion shut off from any possible communication with the outer air by being inverted upon a bed of mercury. he then prepared some pure oxygen and nitrogen gases, and passed them by means of a tube going from the outside of the vessel, up through the mercury into the infusion; so that he thus had it exposed to a perfectly pure atmosphere of the same constituents as the external air. of course, he expected he would get no infusorial animalcules at all in that infusion; but, to his great dismay and discomfiture, he found he almost always did get them. furthermore, it has been found that experiments made in the manner described above answer well with most infusions; but that if you fill the vessel with boiled milk, and then stop the neck with cotton-wool, you 'will' have infusoria. so that you see there were two experiments that brought you to one kind of conclusion, and three to another; which was a most unsatisfactory state of things to arrive at in a scientific inquiry. some few years after this, the question began to be very hotly discussed in france. there was m. pouchet, a professor at rouen, a very learned man, but certainly not a very rigid experimentalist. he published a number of experiments of his own, some of which were very ingenious, to show that if you went to work in a proper way, there was a truth in the doctrine of spontaneous generation. well, it was one of the most fortunate things in the world that m. pouchet took up this question, because it induced a distinguished french chemist, m. pasteur, to take up the question on the other side; and he has certainly worked it out in the most perfect manner. i am glad to say, too, that he has published his researches in time to enable me to give you an account of them. he verified all the experiments which i have just mentioned to you--and then finding those extraordinary anomalies, as in the case of the mercury bath and the milk, he set himself to work to discover their nature. in the case of milk he found it to be a question of temperature. milk in a fresh state is slightly alkaline; and it is a very curious circumstance, but this very slight degree of alkalinity seems to have the effect of preserving the organisms which fall into it from the air from being destroyed at a temperature of degrees, which is the boiling point. but if you raise the temperature degrees when you boil it, the milk behaves like everything else; and if the air with which it comes in contact, after being boiled at this temperature, is passed through a red-hot tube, you will not get a trace of organisms. he then turned his attention to the mercury bath, and found on examination that the surface of the mercury was almost always covered with a very fine dust. he found that even the mercury itself was positively full of organic matters; that from being constantly exposed to the air, it had collected an immense number of these infusorial organisms from the air. well, under these circumstances he felt that the case was quite clear, and that the mercury was not what it had appeared to m. schwann to be,--a bar to the admission of these organisms; but that, in reality, it acted as a reservoir from which the infusion was immediately supplied with the large quantity that had so puzzled him. but not content with explaining the experiments of others, m. pasteur went to work to satisfy himself completely. he said to himself: "if my view is right, and if, in point of fact, all these appearances of spontaneous generation are altogether due to the falling of minute germs suspended in the atmosphere,--why, i ought not only to be able to show the germs, but i ought to be able to catch and sow them, and produce the resulting organisms." he, accordingly, constructed a very ingenious apparatus to enable him to accomplish this trapping of this "germ dust" in the air. he fixed in the window of his room a glass tube, in the centre of which he had placed a ball of gun-cotton, which, as you all know, is ordinary cotton-wool, which, from having been steeped in strong acid, is converted into a substance of great explosive power. it is also soluble in alcohol and ether. one end of the glass tube was, of course, open to the external air; and at the other end of it he placed an aspirator, a contrivance for causing a current of the external air to pass through the tube. he kept this apparatus going for four-and-twenty hours, and then removed the 'dusted' gun-cotton, and dissolved it in alcohol and ether. he then allowed this to stand for a few hours, and the result was, that a very fine dust was gradually deposited at the bottom of it. that dust, on being transferred to the stage of a microscope, was found to contain an enormous number of starch grains. you know that the materials of our food and the greater portion of plants are composed of starch, and we are constantly making use of it in a variety of ways, so that there is always a quantity of it suspended in the air. it is these starch grains which form many of those bright specks that we see dancing in a ray of light sometimes. but besides these, m. pasteur found also an immense number of other organic substances such as spores of fungi, which had been floating about in the air and had got caged in this way. he went farther, and said to himself, "if these really are the things that give rise to the appearance of spontaneous generation, i ought to be able to take a ball of this 'dusted' gun-cotton and put it into one of my vessels, containing that boiled infusion which has been kept away from the air, and in which no infusoria are at present developed, and then, if i am right, the introduction of this gun-cotton will give rise to organisms." accordingly, he took one of these vessels of infusion, which had been kept eighteen months, without the least appearance of life, and by a most ingenious contrivance, he managed to break it open and introduce such a ball of gun-cotton, without allowing the infusion or the cotton ball to come into contact with any air but that which had been subjected to a red heat, and in twenty-four hours he had the satisfaction of finding all the indications of what had been hitherto called spontaneous generation. he had succeeded in catching the germs and developing organisms in the way he had anticipated. it now struck him that the truth of his conclusions might be demonstrated without all the apparatus he had employed. to do this, he took some decaying animal or vegetable substance, such as urine, which is an extremely decomposable substance, or the juice of yeast, or perhaps some other artificial preparation, and filled a vessel having a long tubular neck with it. he then boiled the liquid and bent that long neck into an s shape or zig-zag, leaving it open at the end. the infusion then gave no trace of any appearance of spontaneous generation, however long it might be left, as all the germs in the air were deposited in the beginning of the bent neck. he then cut the tube close to the vessel, and allowed the ordinary air to have free and direct access; and the result of that was the appearance of organisms in it, as soon as the infusion had been allowed to stand long enough to allow of the growth of those it received from the air, which was about forty-eight hours. the result of m. pasteur's experiments proved, therefore, in the most conclusive manner, that all the appearances of spontaneous generation arose from nothing more than the deposition of the germs of organisms which were constantly floating in the air. to this conclusion, however, the objection was made, that if that were the cause, then the air would contain such an enormous number of these germs, that it would be a continual fog. but m. pasteur replied that they are not there in anything like the number we might suppose, and that an exaggerated view has been held on that subject; he showed that the chances of animal or vegetable life appearing in infusions, depend entirely on the conditions under which they are exposed. if they are exposed to the ordinary atmosphere around us, why, of course, you may have organisms appearing early. but, on the other hand, if they are exposed to air from a great height, or from some very quiet cellar, you will often not find a single trace of life. so that m. pasteur arrived at last at the clear and definite result, that all these appearances are like the case of the worms in the piece of meat, which was refuted by redi, simply germs carried by the air and deposited in the liquids in which they afterwards appear. for my own part, i conceive that, with the particulars of m. pasteur's experiments before us, we cannot fail to arrive at his conclusions; and that the doctrine of spontaneous generation has received a final 'coup de grace'. you, of course, understand that all this in no way interferes with the 'possibility' of the fabrication of organic matters by the direct method to which i have referred, remote as that possibility may be. [footnote : those who wish to study fully the doctrines of which i have endeavoured to give some rough and ready illustrations, must read mr. john stuart mill's 'system of logic'.] equinoctial regions of america alexander von humboldt bohn's scientific library. humboldt's personal narrative volume . personal narrative of travels to the equinoctial regions of america during the years - by alexander von humboldt and aime bonpland. translated from the french of alexander von humboldt and edited by thomasina ross. in three volumes volume . london. george bell & sons. . london: portugal st., lincoln's inn. cambridge: deighton, bell and co. new york: the macmillan co. bombay: a.h. wheeler and co. editor's preface. the increasing interest attached to all that part of the american continent situated within and near the tropics, has suggested the publication of the present edition of humboldt's celebrated work, as a portion of the scientific library. prior to the travels of humboldt and bonpland, the countries described in the following narrative were but imperfectly known to europeans. for our partial acquaintance with them we were chiefly indebted to the early navigators, and to some of the followers of the spanish conquistadores. the intrepid men whose courage and enterprise prompted them to explore unknown seas for the discovery of a new world, have left behind them narratives of their adventures, and descriptions of the strange lands and people they visited, which must ever be perused with curiosity and interest; and some of the followers of pizarro and cortez, as well as many learned spaniards who proceeded to south america soon after the conquest, were the authors of historical and other works of high value. but these writings of a past age, however curious and interesting, are deficient in that spirit of scientific investigation which enhances the importance and utility of accounts of travels in distant regions. in more recent times, the researches of la condamine tended in a most important degree to promote geographical knowledge; and he, as well as other eminent botanists who visited the coasts of south america, and even ascended the andes, contributed by their discoveries and collections to augment the vegetable riches of the old world. but, in their time, geology as a science had little or no existence. of the structure of the giant mountains of our globe scarcely anything was understood; whilst nothing was known beneath the earth in the new world, except what related to her mines of gold and silver. it remained for humboldt to supply all that was wanting, by the publication of his personal narrative. in this, more than in any other of his works, he shows his power of contemplating nature in all her grandeur and variety. the researches and discoveries of humboldt's able coadjutor and companion, m. bonpland, afford not only a complete picture of the botany of the equinoctial regions of america, but of that of other places visited by the travellers on their voyage thither. the description of the island of teneriffe and the geography of its vegetation, show how much was discovered by humboldt and bonpland which had escaped the observation of discerning travellers who had pursued the same route before them. indeed, the whole account of the canary islands presents a picture which cannot be contemplated without the deepest interest, even by persons comparatively indifferent to the study of nature. it is, perhaps, scarcely necessary to remind the reader that since the time when this work was first published in paris, the separation of the spanish colonies from the mother-country, together with subsequent political events, have wrought great changes in the governments of the south american states, as well as in the social condition of their inhabitants. one consequence of these changes has been to render obsolete some facts and observations relating to subjects, political, commercial, and statistical, interspersed through this work. however useful such matter might have been on its original publication, it is wholly irrelevant to the existing state of things, and consequently it has been deemed advisable to omit it. by this curtailment, together with that of some meteorological tables and discussions of very limited interest, the work has been divested of its somewhat lengthy and discursive character, and condensed within dimensions better adapted to the taste and requirements of the present time. an english translation of this work by helen maria williams, was published many years ago, and is now out of print. though faultless as respects correctness of interpretation, it abounds in foreign turns of expression, and is somewhat deficient in that fluency of style without which a translated work is unsatisfactory to the english reader. in the edition now presented to the public it is hoped that these objections are in some degree removed. a careful english version is given of all the spanish and portuguese terms, phrases, and quotations which occur in this work. though the author has only in some few instances given a french translation of these passages, yet it is presumed that the interpretation of the whole in english will not be deemed superfluous; this new edition of the "personal narrative" having been undertaken with the view of presenting the work in the form best suited for the instruction and entertainment of the general reader. t.r. london, december . *** measures: in this narrative, as well as in the political essay on new spain, all the prices are reckoned in piastres, and silver reals (reales de plata). eight of these reals are equivalent to a piastre, or one hundred and five sous, french money ( shillings / pence english). nouv. esp. volume pages , and . the magnetic dip is always measured in this work, according to the centesimal division, if the contrary be not expressly mentioned. one flasco contains or cubic inches, paris measure. english pounds = french pounds; and spanish pounds = french pounds. an arpent des eaux et forets, or legal acre of france, of which . = hectare. it is about / acre english. a tablon, equal to square toises, contains nearly an acre and one-fifth: a legal acre has square toises, and . legal acre is equal one hectare. for the sake of accuracy, the french measures, as given by the author, and the indications of the centigrade thermometer, are retained in the translation. the following tables may, therefore, be found useful. table of linear measure. toise = feet . inches. foot = . inches. metre = feet . inches. (transcriber's note: the 'toise' was introduced by charlemagne in ; it originally represented the distance between the fingertips of a man with outstretched arms, and is thus the same as the british 'fathom'. during the founding of the metric system, less than years before the date of this work, the 'toise' was assigned a value of . meters, or a little over two yards. the 'foot'; actually the 'french foot', or 'pied', is defined as / of a 'toise', and is a little over an english foot.) centigrade thermometer reduced to fahrenheit's scale. cent. fahr. cent. fahr. cent. fahr. cent. fahr. - . . . - . . . . - . . . . - . . . . - . - . . . - . . . . - . . . . - . . . . - . - . . . - . . . . - . . . . - - . . . . - - . - - . . . - - . . . . - - . . . . - - . . . . - - . - - . . . - - . . . . - - . . . . - - . . . . - - . - - . . . - - . . . . - - . . . . - - . . . . - - . - - . . - . - - . . . - . - - . . . - . - - . . . - . - - . *** volume . contents. editor's preface. introduction by the author. chapter . . preparations.--instruments.--departure from spain.-- landing at the canary islands. chapter . . stay at tenerife.--journey from santa cruz to orotava.--excursion to the summit of the peak of teyde. chapter . . passage from tenerife to south america.-- the island of tobago.--arrival at cumana. chapter . . first abode at cumana.--banks of the manzanares. chapter . . peninsula of araya.--salt-marshes.-- ruins of the castle of santiago. chapter . . mountains of new andalucia.--valley of the cumanacoa.-- summit of the cocollar.--missions of the chayma indians. chapter . . convent of caripe.--cavern of the guacharo.--nocturnal birds. chapter . . departure from caripe.--mountain and forest of santa maria.-- mission of catuaro.--port of cariaco. chapter . . physical constitution and manners of the chaymas.--their language.-- filiation of the nations which inhabit new andalucia.-- pariagotos seen by columbus. chapter . . second abode at cumana.--earthquakes.--extraordinary meteors. chapter . . passage from cumana to la guayra.--morro of nueva barcelona.-- cape codera.--road from la guayra to caracas. chapter . . general view of the provinces of venezuela.-- diversity of their interests.--city and valley of caracas.-- climate. chapter . . abode at caracas.--mountains in the vicinity of the town.-- excursion to the summit of the silla.--indications of mines. chapter . . earthquakes at caracas.--connection of those phenomena with the volcanic eruptions of the west india islands. chapter . . departure from caracas.--mountains of san pedro and of los teques.-- la victoria.--valleys of aragua. *** introduction by the author. many years have elapsed since i quitted europe, to explore the interior of the new continent. devoted from my earliest youth to the study of nature, feeling with enthusiasm the wild beauties of a country guarded by mountains and shaded by ancient forests, i experienced in my travels, enjoyments which have amply compensated for the privations inseparable from a laborious and often agitated life. these enjoyments, which i endeavoured to impart to my readers in my 'remarks upon the steppes,' and in the 'essay on the physiognomy of plants,' were not the only fruits i reaped from an undertaking formed with the design of contributing to the progress of natural philosophy. i had long prepared myself for the observations which were the principal object of my journey to the torrid zone. i was provided with instruments of easy and convenient use, constructed by the ablest makers, and i enjoyed the special protection of a government which, far from presenting obstacles to my investigations, constantly honoured me with every mark of regard and confidence. i was aided by a courageous and enlightened friend, and it was singularly propitious to the success of our participated labour, that the zeal and equanimity of that friend never failed, amidst the fatigues and dangers to which we were sometimes exposed. under these favourable circumstances, traversing regions which for ages have remained almost unknown to most of the nations of europe, i might add even to spain, m. bonpland and myself collected a considerable number of materials, the publication of which may throw some light on the history of nations, and advance the study of nature. i had in view a two-fold purpose in the travels of which i now publish the historical narrative. i wished to make known the countries i had visited; and to collect such facts as are fitted to elucidate a science of which we as yet possess scarcely the outline, and which has been vaguely denominated natural history of the world, theory of the earth, or physical geography. the last of these two objects seemed to me the most important. i was passionately devoted to botany and certain parts of zoology, and i flattered myself that our investigations might add some new species to those already known, both in the animal and vegetable kingdoms; but preferring the connection of facts which have been long observed, to the knowledge of insulated facts, although new, the discovery of an unknown genus seemed to me far less interesting than an observation on the geographical relations of the vegetable world, on the migrations of the social plants, and the limit of the height which their different tribes attain on the flanks of the cordilleras. the natural sciences are connected by the same ties which link together all the phenomena of nature. the classification of the species, which must be considered as the fundamental part of botany, and the study of which is rendered attractive and easy by the introduction of natural methods, is to the geography of plants what descriptive mineralogy is to the indication of the rocks constituting the exterior crust of the globe. to comprehend the laws observed in the position of these rocks, to determine the age of their successive formations, and their identity in the most distant regions, the geologist should be previously acquainted with the simple fossils which compose the mass of mountains, and of which the names and character are the object of oryctognostical knowledge. it is the same with that part of the natural history of the globe which treats of the relations plants have to each other, to the soil whence they spring, or to the air which they inhale and modify. the progress of the geography of plants depends in a great measure on that of descriptive botany; and it would be injurious to the advancement of science, to attempt rising to general ideas, whilst neglecting the knowledge of particular facts. i have been guided by these considerations in the course of my inquiries; they were always present to my mind during the period of my preparatory studies. when i began to read the numerous narratives of travels, which compose so interesting a part of modern literature, i regretted that travellers, the most enlightened in the insulated branches of natural history, were seldom possessed of sufficient variety of knowledge to avail themselves of every advantage arising from their position. it appeared to me, that the importance of the results hitherto obtained did not keep pace with the immense progress which, at the end of the eighteenth century, had been made in several departments of science, particularly geology, the history of the modifications of the atmosphere, and the physiology of animals and plants. i saw with regret, (and all scientific men have shared this feeling) that whilst the number of accurate instruments was daily increasing, we were still ignorant of the height of many mountains and elevated plains; of the periodical oscillations of the aerial ocean; of the limit of perpetual snow within the polar circle and on the borders of the torrid zone; of the variable intensity of the magnetic forces, and of many other phenomena equally important. maritime expeditions and circumnavigatory voyages have conferred just celebrity on the names of the naturalists and astronomers who have been appointed by various governments to share the dangers of those undertakings; but though these eminent men have given us precise notions of the external configuration of countries, of the natural history of the ocean, and of the productions of islands and coasts, it must be admitted that maritime expeditions are less fitted to advance the progress of geology and other parts of physical science, than travels into the interior of a continent. the advancement of the natural sciences has been subordinate to that of geography and nautical astronomy. during a voyage of several years, the land but seldom presents itself to the observation of the mariner, and when, after lengthened expectation, it is descried, he often finds it stripped of its most beautiful productions. sometimes, beyond a barren coast, he perceives a ridge of mountains covered with verdure, but its distance forbids examination, and the view serves only to excite regret. journeys by land are attended with considerable difficulties in the conveyance of instruments and collections, but these difficulties are compensated by advantages which it is unnecessary to enumerate. it is not by sailing along a coast that we can discover the direction of chains of mountains, and their geological constitution, the climate of each zone, and its influence on the forms and habits of organized beings. in proportion to the extent of continents, the greater on the surface of the soil are the riches of animal and vegetable productions; the more distant the central chain of mountains from the sea-shore, the greater is the variety in the bosom of the earth, of those stony strata, the regular succession of which unfolds the history of our planet. as every being considered apart is impressed with a particular type, so, in like manner, we find the same distinctive impression in the arrangement of brute matter organized in rocks, and also in the distribution and mutual relations of plants and animals. the great problem of the physical description of the globe, is the determination of the form of these types, the laws of their relations with each other, and the eternal ties which link the phenomena of life, and those of inanimate nature. having stated the general object i had in view in my expeditions, i will now hasten to give a slight sketch of the whole of the collections and observations which we have accumulated, and the union of which is the aim and end of every scientific journey. the maritime war, during our abode in america, having rendered communication with europe very uncertain, we found ourselves compelled, in order to diminish the chance of losses, to form three different collections. of these, the first was embarked for spain and france, the second for the united states and england, and the third, which was the most considerable, remained almost constantly under our own eyes. towards the close of our expedition, this last collection formed forty-two boxes, containing an herbal of six thousand equinoctial plants, seeds, shells, insects, and (what had hitherto never been brought to europe) geological specimens, from the chimborazo, new grenada, and the banks of the river amazon. after our journey to the orinoco, we left a part of these collections at the island of cuba, intending to take them on our return from peru to mexico. the rest followed us during the space of five years, on the chain of the andes, across new spain, from the shores of the pacific to the coasts of the caribbean sea. the conveyance of these objects, and the minute care they required, occasioned embarrassments scarcely conceiveable even by those who have traversed the most uncultivated parts of europe. our progress was often retarded by the necessity of dragging after us, during expeditions of five or six months, twelve, fifteen, and sometimes more than twenty loaded mules, exchanging these animals every eight or ten days, and superintending the indians who were employed in driving the numerous caravan. often, in order to add to our collections of new mineral substances, we found ourselves obliged to throw away others, which we had collected a considerable time before. these sacrifices were not less vexatious than the losses we accidentally sustained. sad experience taught us but too late, that from the sultry humidity of the climate, and the frequent falls of the beasts of burden, we could preserve neither the skins of animals hastily prepared, nor the fishes and reptiles placed in phials filled with alcohol. i enter into these details, because, though little interesting in themselves, they serve to show that we had no means of bringing back, in their natural state, many objects of zoology and comparative anatomy, of which we have published descriptions and drawings. notwithstanding some obstacles, and the expense occasioned by the carriage of these articles, i had reason to applaud the resolution i had taken before my departure, of sending to europe the duplicates only of the productions we collected. i cannot too often repeat, that when the seas are infested with privateers, a traveller can be sure only of the objects in his own possession. a very few of the duplicates, which we shipped for europe during our abode in america, were saved; the greater part fell into the hands of persons who feel no interest for science. when a ship is condemned in a foreign port, boxes containing only dried plants or stones, instead of being sent to the scientific men to whom they are addressed, are put aside and forgotten. some of our geological collections taken in the pacific were, however, more fortunate. we were indebted for their preservation to the generous activity of sir joseph banks, president of the royal society of london, who, amidst the political agitations of europe, unceasingly laboured to strengthen the bonds of union between scientific men of all nations. in our investigations we have considered each phenomenon under different aspects, and classed our remarks according to the relations they bear to each other. to afford an idea of the method we have followed, i will here add a succinct enumeration of the materials with which we were furnished for describing the volcanoes of antisana and pichincha, as well as that of jorullo: the latter, during the night of the th of september, , rose from the earth one thousand five hundred and seventy-eight french feet above the surrounding plains of mexico. the position of these singular mountains in longitude and latitude was ascertained by astronomical observations. we took the heights of the different parts by the aid of the barometer, and determined the dip of the needle and the intensity of the magnetic forces. our collections contain the plants which are spread over the flanks of these volcanoes, and specimens of different rocks which, superposed one upon another, constitute their external coat. we are enabled to indicate, by measures sufficiently exact, the height above the level of the ocean, at which we found each group of plants, and each volcanic rock. our journals furnish us with a series of observations on the humidity, the temperature, the electricity, and the degree of transparency of the air on the brinks of the craters of pichincha and jorullo; they also contain topographical plans and geological profiles of these mountains, founded in part on the measure of vertical bases, and on angles of altitude. each observation has been calculated according to the tables and the methods which are considered most exact in the present state of our knowledge; and in order to judge of the degree of confidence which the results may claim, we have preserved the whole detail of our partial operations. it would have been possible to blend these different materials in a work devoted wholly to the description of the volcanoes of peru and new spain. had i given the physical description of a single province, i could have treated separately everything relating to its geography, mineralogy, and botany; but how could i interrupt the narrative of a journey, a disquisition on the manners of a people, or the great phenomena of nature, by an enumeration of the productions of the country, the description of new species of animals and plants, or the detail of astronomical observations. had i adopted a mode of composition which would have included in one and the same chapter all that has been observed on one particular point of the globe, i should have prepared a work of cumbrous length, and devoid of that clearness which arises in a great measure from the methodical distribution of matter. notwithstanding the efforts i have made to avoid, in this narrative, the errors i had to dread, i feel conscious that i have not always succeeded in separating the observations of detail from those general results which interest every enlightened mind. these results comprise in one view the climate and its influence on organized beings, the aspect of the country, varied according to the nature of the soil and its vegetable covering, the direction of the mountains and rivers which separate races of men as well as tribes of plants; and finally, the modifications observable in the condition of people living in different latitudes, and in circumstances more or less favourable to the development of their faculties. i do not fear having too much enlarged on objects so worthy of attention: one of the noblest characteristics which distinguish modern civilization from that of remoter times is, that it has enlarged the mass of our conceptions, rendered us more capable of perceiving the connection between the physical and intellectual world, and thrown a more general interest over objects which heretofore occupied only a few scientific men, because those objects were contemplated separately, and from a narrower point of view. as it is probable that these volumes will obtain the attention of a greater number of readers than the detail of my observations merely scientific, or my researches on the population, the commerce, and the mines of new spain, i may be permitted here to enumerate all the works which i have hitherto published conjointly with m. bonpland. when several works are interwoven in some sort with each other, it may perhaps be interesting to the reader to know the sources whence he may obtain more circumstantial information. .i. . astronomical observations, trigonometrical operations, and barometrical measurements made during the course of a journey to the equinoctial regions of the new continent, from to . this work, to which are added historical researches on the position of several points important to navigators, contains, first, the original observations which i made from the twelfth degree of southern to the forty-first degree of northern latitude; the transits of the sun and stars over the meridian; distances of the moon from the sun and the stars; occultations of the satellites; eclipses of the sun and moon; transits of mercury over the disc of the sun; azimuths; circum-meridian altitudes of the moon, to determine the longitude by the differences of declination; researches on the relative intensity of the light of the austral stars; geodesical measures, etc. secondly, a treatise on the astronomical refractions in the torrid zone, considered as the effect of the decrement of caloric in the strata of the air; thirdly, the barometric measurement of the cordillera of the andes, of mexico, of the province of venezuela, of the kingdom of quito, and of new grenada; followed by geological observations, and containing the indication of four hundred and fifty-three heights, calculated according to the method of m. laplace, and the new co-efficient of m. ramond; fourthly, a table of near seven hundred geographical positions on the new continent; two hundred and thirty-five of which have been determined by my own observations, according to the three co-ordinates of longitude, latitude, and height. .i. . equinoctial plants collected in mexico, in the island of cuba, in the provinces of caracas, cumana, and barcelona, on the andes of new grenada, quito, and peru, and on the banks of the rio negro, the orinoco, and the river amazon. m. bonpland has in this work given figures of more than forty new genera of plants of the torrid zone, classed according to their natural families. the methodical descriptions of the species are both in french and latin, and are accompanied by observations on the medicinal properties of the plants, their use in the arts, and the climate of the countries in which they are found. .i. . monography of the melastoma, rhexia, and other genera of this order of plants. comprising upwards of a hundred and fifty species of melastomaceae, which we collected during the course of our expeditions, and which form one of the most beautiful ornaments of tropical vegetation. m. bonpland has added the plants of the same family, which, among many other rich stores of natural history, m. richard collected in his interesting expedition to the antilles and french guiana, and the descriptions of which he has communicated to us. .i. . essay on the geography of plants, accompanied by a physical table of the equinoctial regions, founded on measures taken from the tenth degree of northern to the tenth degree of southern latitude. i have endeavoured to collect in one point of view the whole of the physical phenomena of that part of the new continent comprised within the limits of the torrid zone from the level of the pacific to the highest summit of the andes; namely, the vegetation, the animals, the geological relations, the cultivation of the soil, the temperature of the air, the limit of perpetual snow, the chemical constitution of the atmosphere, its electrical intensity, its barometrical pressure, the decrement of gravitation, the intensity of the azure colour of the sky, the diminution of light during its passage through the successive strata of the air, the horizontal refractions, and the heat of boiling water at different heights. fourteen scales, disposed side by side with a profile of the andes, indicate the modifications to which these phenomena are subject from the influence of the elevation of the soil above the level of the sea. each group of plants is placed at the height which nature has assigned to it, and we may follow the prodigious variety of their forms from the region of the palms and arborescent ferns to those of the johannesia (chuquiraga, juss.), the gramineous plants, and lichens. these regions form the natural divisions of the vegetable empire; and as perpetual snow is found in each climate at a determinate height, so, in like manner, the febrifuge species of the quinquina (cinchona) have their fixed limits, which i have marked in the botanical chart belonging to this essay. .i. . observations on zoology and comparative anatomy. i have comprised in this work the history of the condor; experiments on the electrical action of the gymnotus; a treatise on the larynx of the crocodiles, the quadrumani, and birds of the tropics; the description of several new species of reptiles, fishes, birds, monkeys, and other mammalia but little known. m. cuvier has enriched this work with a very comprehensive treatise on the axolotl of the lake of mexico, and on the genera of the protei. that naturalist has also recognized two new species of mastodons and an elephant among the fossil bones of quadrupeds which we brought from north and south america. for the description of the insects collected by m. bonpland we are indebted to m. latreille, whose labours have so much contributed to the progress of entomology in our times. the second volume of this work contains figures of the mexican, peruvian, and aturian skulls, which we have deposited in the museum of natural history at paris, and respecting which blumenbach has published observations in the 'decas quinta craniorum diversarum gentium.' .i. . political essay on the kingdom of new spain, with a physical and geographical atlas, founded on astronomical observations and trigonometrical and barometrical measurements. this work, based on numerous official memoirs, presents, in six divisions, considerations on the extent and natural appearance of mexico, on the population, on the manners of the inhabitants, their ancient civilization, and the political division of their territory. it embraces also the agriculture, the mineral riches, the manufactures, the commerce, the finances, and the military defence of that vast country. in treating these different subjects i have endeavoured to consider them under a general point of view; i have drawn a parallel not only between new spain, the other spanish colonies, and the united states of north america, but also between new spain and the possessions of the english in asia; i have compared the agriculture of the countries situated in the torrid zone with that of the temperate climates; and i have examined the quantity of colonial produce necessary to europe in the present state of civilization. in tracing the geological description of the richest mining districts in mexico, i have, in short, given a statement of the mineral produce, the population, the imports and exports of the whole of spanish america. i have examined several questions which, for want of precise data, had not hitherto been treated with the attention they demand, such as the influx and reflux of metals, their progressive accumulation in europe and asia, and the quantity of gold and silver which, since the discovery of america down to our own times, the old world has received from the new. the geographical introduction at the beginning of this work contains the analysis of the materials which have been employed in the construction of the mexican atlas. .i. . views of the cordilleras, and monuments of the indigenous nations of the new continent.* (*atlas pittoresque, ou vues des cordilleres, volume folio, with plates, part of which are coloured, accompanied by explanatory treatises. this work may be considered as the atlas to the historical narrative of the travels.) this work is intended to represent a few of the grand scenes which nature presents in the lofty chain of the andes, and at the same time to throw some light on the ancient civilization of the americans, through the study of their monuments of architecture, their hieroglyphics, their religious rites, and their astrological reveries. i have given in this work a description of the teocalli, or mexican pyramids, and have compared their structure with that of the temple of belus. i have described the arabesques which cover the ruins of mitla, the idols in basalt ornamented with the calantica of the heads of isis; and also a considerable number of symbolical paintings, representing the serpent-woman (the mexican eve), the deluge of coxcox, and the first migrations of the natives of the aztec race. i have endeavoured to prove the striking analogies existing between the calendar of the toltecs and the catasterisms of their zodiac, and the division of time of the people of tartary and thibet, as well as the mexican traditions on the four regenerations of the globe, the pralayas of the hindoos, and the four ages of hesiod. in this work i have also included (in addition to the hieroglyphical paintings i brought to europe), fragments of all the aztec manuscripts, collected in rome, veletri, vienna, and dresden, and one of which reminds us, by its lineary symbols, of the kouas of the chinese. together with the rude monuments of the aborigines of america, this volume contains picturesque views of the mountainous countries which those people inhabited; for example, the cataract of tequendama, chimborazo, the volcano of jorullo and cayambe, the pyramidal summit of which, covered with eternal ice, is situated directly under the equinoctial line. in every zone the configuration of the ground, the physiognomy of the plants, and the aspect of lovely or wild scenery, have great influence on the progress of the arts, and on the style which distinguishes their productions. this influence is so much the more perceptible in proportion as man is farther removed from civilization. i could have added to this work researches on the character of languages, which are the most durable monuments of nations. i have collected a number of materials on the languages of america, of which mm. frederic schlegel and vater have made use; the former in his considerations on the hindoos, the latter in his continuation of the mithridates of adelung, in the ethnographical magazine, and in his inquiries into the population of the new continent. these materials are now in the hands of my brother, william von humboldt, who, during his travels in spain, and a long abode at rome, formed the richest collection of american vocabularies in existence. his extensive knowledge of the ancient and modern languages has enabled him to trace some curious analogies in relation to this subject, so important to the philosophical study of the history of man. a part of his labours will find a place in this narrative. of the different works which i have here enumerated, the second and third were composed by m. bonpland, from the observations which he made in a botanical journal. this journal contains more than four thousand methodical descriptions of equinoctial plants, a ninth part only of which have been made by me. they appear in a separate publication, under the title of nova genera et species plantariem. in this work will be found, not only the new species we collected, which, after a careful examination by one of the first botanists of the age, professor willdenouw, are computed to amount to fourteen or fifteen hundred, but also the interesting observations made by m. bonpland on plants hitherto imperfectly described. the plates of this work are all engraved according to the method followed by m. labillardiere, in the specimen planterum novae hollandiae, a work remarkable for profound research and clearness of arrangement. after having distributed into separate works all that belongs to astronomy, botany, zoology, the political description of new spain, and the history of the ancient civilization of certain nations of the new continent, there still remained many general results and local descriptions, which i might have collected into separate treatises. i had, during my journey, prepared papers on the races of men in south america; on the missions of the orinoco; on the obstacles to the progress of society in the torrid zone arising from the climate and the strength of vegetation; on the character of the landscape in the cordilleras of the andes compared with that of the alps in switzerland; on the analogies between the rocks of the two hemispheres; on the physical constitution of the air in the equinoctial regions, etc. i had left europe with the firm intention of not writing what is usually called the historical narrative of a journey, but to publish the fruit of my inquiries in works merely descriptive; and i had arranged the facts, not in the order in which they successively presented themselves, but according to the relation they bore to each other. amidst the overwhelming majesty of nature, and the stupendous objects she presents at every step, the traveller is little disposed to record in his journal matters which relate only to himself, and the ordinary details of life. i composed a very brief itinerary during the course of my excursions on the rivers of south america, and in my long journeys by land. i regularly described (and almost always on the spot) the visits i made to the summits of volcanoes, or mountains remarkable for their height; but the entries in my journal were interrupted whenever i resided in a town, or when other occupations prevented me from continuing a work which i considered as having only a secondary interest. whenever i wrote in my journal, i had no other motive than the preservation of some of those fugitive ideas which present themselves to a naturalist, whose life is almost wholly passed in the open air. i wished to make a temporary collection of such facts as i had not then leisure to class, and note down the first impressions, whether agreeable or painful, which i received from nature or from man. far from thinking at the time that those pages thus hurriedly written would form the basis of an extensive work to be offered to the public, it appeared to me, that my journal, though it might furnish certain data useful to science, would present very few of those incidents, the recital of which constitutes the principal charm of an itinerary. the difficulties i have experienced since my return, in the composition of a considerable number of treatises, for the purpose of making known certain classes of phenomena, insensibly overcame my repugnance to write the narrative of my journey. in undertaking this task, i have been guided by the advice of many estimable persons, who honour me with their friendship. i also perceived that such a preference is given to this sort of composition, that scientific men, after having presented in an isolated form the account of their researches on the productions, the manners, and the political state of the countries through which they have passed, imagine that they have not fulfilled their engagements with the public, till they have written their itinerary. an historical narrative embraces two very distinct objects; the greater or the less important events connected with the purpose of the traveller, and the observations he has made during his journey. the unity of composition also, which distinguishes good works from those on an ill-constructed plan, can be strictly observed only when the traveller describes what has passed under his own eye; and when his principal attention has been fixed less on scientific observations than on the manners of different people and the great phenomena of nature. now, the most faithful picture of manners is that which best displays the relations of men towards each other. the character of savage or civilized life is portrayed either in the obstacles a traveller meets with, or in the sensations he feels. it is the traveller himself whom we continually desire to see in contact with the objects which surround him; and his narration interests us the more, when a local tint is diffused over the description of a country and its inhabitants. such is the source of the interest excited by the history of those early navigators, who, impelled by intrepidity rather than by science, struggled against the elements in their search for the discovery of a new world. such is the irresistible charm attached to the fate of that enterprising traveller (mungo park.), who, full of enthusiasm and energy, penetrated alone into the centre of africa, to discover amidst barbarous nations the traces of ancient civilization. in proportion as travels have been undertaken by persons whose views have been directed to researches into descriptive natural history, geography, or political economy, itineraries have partly lost that unity of composition, and that simplicity which characterized those of former ages. it is now become scarcely possible to connect so many different materials with the detail of other events; and that part of a traveller's narrative which we may call dramatic gives way to dissertations merely descriptive. the numerous class of readers who prefer agreeable amusement to solid instruction, have not gained by the exchange; and i am afraid that the temptation will not be great to follow the course of travellers who are incumbered with scientific instruments and collections. to give greater variety to my work, i have often interrupted the historical narrative by descriptions. i first represent phenomena in the order in which they appeared; and i afterwards consider them in the whole of their individual relations. this mode has been successfully followed in the journey of m. de saussure, whose most valuable work has contributed more than any other to the advancement of science. often, amidst dry discussions on meteorology, it contains many charming descriptions; such as those of the modes of life of the inhabitants of the mountains, the dangers of hunting the chamois, and the sensations felt on the summit of the higher alps. there are details of ordinary life which it may be useful to note in an itinerary, because they serve for the guidance of those who afterwards journey through the same countries. i have preserved a few, but have suppressed the greater part of those personal incidents which present no particular interest, and which can be rendered amusing only by the perfection of style. with respect to the country which has been the object of my investigations, i am fully sensible of the great advantages enjoyed by persons who travel in greece, egypt, the banks of the euphrates, and the islands of the pacific, in comparison with those who traverse the continent of america. in the old world, nations and the distinctions of their civilization form the principal points in the picture; in the new world, man and his productions almost disappear amidst the stupendous display of wild and gigantic nature. the human race in the new world presents only a few remnants of indigenous hordes, slightly advanced in civilization; or it exhibits merely the uniformity of manners and institutions transplanted by european colonists to foreign shores. information which relates to the history of our species, to the various forms of government, to monuments of art, to places full of great remembrances, affect us far more than descriptions of those vast solitudes which seem destined only for the development of vegetable life, and to be the domain of wild animals. the savages of america, who have been the objects of so many systematic reveries, and on whom m. volney has lately published some accurate and intelligent observations, inspire less interest since celebrated navigators have made known to us the inhabitants of the south sea islands, in whose character we find a striking mixture of perversity and meekness. the state of half-civilization existing among those islanders gives a peculiar charm to the description of their manners. a king, followed by a numerous suite, presents the fruits of his orchard; or a funeral is performed amidst the shade of the lofty forest. such pictures, no doubt, have more attraction than those which pourtray the solemn gravity of the inhabitant of the banks of the missouri or the maranon. america offers an ample field for the labours of the naturalist. on no other part of the globe is he called upon more powerfully by nature to raise himself to general ideas on the cause of phenomena and their mutual connection. to say nothing of that luxuriance of vegetation, that eternal spring of organic life, those climates varying by stages as we climb the flanks of the cordilleras, and those majestic rivers which a celebrated writer (m. chateaubriand.) has described with such graceful accuracy, the resources which the new world affords for the study of geology and natural philosophy in general have been long since acknowledged. happy the traveller who may cherish the hope that he has availed himself of the advantages of his position, and that he has added some new facts to the mass of those previously acquired! since i left america, one of those great revolutions, which at certain periods agitate the human race, has broken out in the spanish colonies, and seems to prepare new destinies for a population of fourteen millions of inhabitants, spreading from the southern to the northern hemisphere, from the shores of the rio de la plata and chile to the remotest part of mexico. deep resentments, excited by colonial legislation, and fostered by mistrustful policy, have stained with blood regions which had enjoyed, for the space of nearly three centuries, what i will not call happiness but uninterrupted peace. at quito several of the most virtuous and enlightened citizens have perished, victims of devotion to their country. while i am giving the description of regions, the remembrance of which is so dear to me, i continually light on places which recall to my mind the loss of a friend. when we reflect on the great political agitations of the new world, we observe that the spanish americans are by no means in so favourable a position as the inhabitants of the united states; the latter having been prepared for independence by the long enjoyment of constitutional liberty. internal dissensions are chiefly to be dreaded in regions where civilization is but slightly rooted, and where, from the influence of climate, forests may soon regain their empire over cleared lands if their culture be abandoned. it may also be feared that, during a long series of years, no foreign traveller will be enabled to traverse all the countries which i have visited. this circumstance may perhaps add to the interest of a work which pourtrays the state of the greater part of the spanish colonies at the beginning of the th century. i even venture to indulge the hope that this work will be thought worthy of attention when passions shall be hushed into peace, and when, under the influence of a new social order, those countries shall have made rapid progress in public welfare. if then some pages of my book are snatched from oblivion, the inhabitant of the banks of the orinoco and the atabapo will behold with delight populous cities enriched by commerce, and fertile fields cultivated by the hands of free men, on those very spots where, at the time of my travels, i found only impenetrable forests and inundated lands. *** personal narrative of a journey to the equinoctial regions of the new continent. volume . chapter . . preparations. instruments. departure from spain. landing at the canary islands. from my earliest youth i felt an ardent desire to travel into distant regions, seldom visited by europeans. this desire is characteristic of a period of our existence when appears an unlimited horizon, and when we find an irresistible attraction in the impetuous agitations of the mind, and the image of positive danger. though educated in a country which has no direct communication with either the east or the west indies, living amidst mountains remote from coasts, and celebrated for their numerous mines, i felt an increasing passion for the sea and distant expeditions. objects with which we are acquainted only by the animated narratives of travellers have a peculiar charm; imagination wanders with delight over that which is vague and undefined; and the pleasures we are deprived of seem to possess a fascinating power, compared with which all we daily feel in the narrow circle of sedentary life appears insipid. the taste for herborisation, the study of geology, rapid excursions to holland, england, and france, with the celebrated mr. george forster, who had the happiness to accompany captain cook in his second expedition round the globe, contributed to give a determined direction to the plan of travels which i had formed at eighteen years of age. no longer deluded by the agitation of a wandering life, i was anxious to contemplate nature in all her variety of wild and stupendous scenery; and the hope of collecting some facts useful to the advancement of science, incessantly impelled my wishes towards the luxuriant regions of the torrid zone. as personal circumstances then prevented me from executing the projects by which i was so powerfully influenced, i had leisure to prepare myself during six years for the observations i proposed to make on the new continent, as well as to visit different parts of europe, and to explore the lofty chain of the alps, the structure of which i might afterwards compare with that of the andes of quito and of peru. i had traversed a part of italy in , but had not been able to visit the volcanic regions of naples and sicily; and i regretted leaving europe without having seen vesuvius, stromboli, and etna. i felt, that in order to form a proper judgment of many geological phenomena, especially of the nature of the rocks of trap-formation, it was necessary to examine the phenomena presented by burning volcanoes. i determined therefore to return to italy in the month of november, . i made a long stay at vienna, where the fine collections of exotic plants, and the friendship of messrs. de jacquin, and joseph van der schott, were highly useful to my preparatory studies. i travelled with m. leopold von buch, through several cantons of salzburg and styria, countries alike interesting to the landscape-painter and the geologist; but just when i was about to cross the tyrolese alps, the war then raging in italy obliged me to abandon the project of going to naples. a short time before, a gentleman passionately fond of the fine arts, and who had visited the coasts of greece and illyria to inspect their monuments, made me a proposal to accompany him in an expedition to upper egypt. this expedition was to occupy only eight months. provided with astronomical instruments and able draughtsmen, we were to ascend the nile as far as assouan, after minutely examining the positions of the said, between tentyris and the cataracts. though my views had not hitherto been fixed on any region but the tropics, i could not resist the temptation of visiting countries so celebrated in the annals of human civilization. i therefore accepted this proposition, but with the express condition, that on our return to alexandria i should be at liberty to continue my journey through syria and palestine. the studies which i entered upon with a view to this new project, i afterwards found useful, when i examined the relations between the barbarous monuments of mexico, and those belonging to the nations of the old world. i thought myself on the point of embarking for egypt, when political events forced me to abandon a plan which promised me so much satisfaction. an expedition of discovery in the south sea, under the direction of captain baudin, was then preparing in france. the plan was great, bold, and worthy of being executed by a more enlightened commander. the purpose of this expedition was to visit the spanish possessions of south america, from the mouth of the river plata to the kingdom of quito and the isthmus of panama. after visiting the archipelago of the pacific, and exploring the coasts of new holland, from van diemen's land to that of nuyts, both vessels were to stop at madagascar, and return by the cape of good hope. i was in paris when the preparations for this voyage were begun. i had but little confidence in the personal character of captain baudin, who had given cause of discontent to the court of vienna, when he was commissioned to conduct to brazil one of my friends, the young botanist, van der schott; but as i could not hope, with my own resources, to make a voyage of such extent, and view so fine a portion of the globe, i determined to take the chances of this expedition. i obtained permission to embark, with the instruments i had collected, in one of the vessels destined for the south sea, and i reserved to myself the liberty of leaving captain baudin whenever i thought proper. m. michaux, who had already visited persia and a part of north america, and m. bonpland, with whom i then formed the friendship that still unites us, were appointed to accompany this expedition as naturalists. i had flattered myself during several months with the idea of sharing the labours directed to so great and honourable an object when the war which broke out in germany and italy, determined the french government to withdraw the funds granted for their voyage of discovery, and adjourn it to an indefinite period. deeply mortified at finding the plans i had formed during many years of my life overthrown in a single day, i sought at any risk the speediest means of quitting europe, and engaging in some enterprise which might console me for my disappointment. i became acquainted with a swedish consul, named skioldebrand, who having been appointed by his court to carry presents to the dey of algiers, was passing through paris, to embark at marseilles. this estimable man had resided a long time on the coast of africa; and being highly respected by the government of algiers, he could easily procure me permission to visit that part of the chain of the atlas which had not been the object of the important researches of m. desfontaines. he despatched every year a vessel for tunis, where the pilgrims embarked for mecca, and he promised to convey me by the same medium to egypt. i eagerly seized so favourable an opportunity, and thought myself on the point of executing a plan which i had formed previously to my arrival in france. no mineralogist had yet examined that lofty chain of mountains which, in the empire of morocco, rises to the limits of the perpetual snow. i flattered myself, that, after executing some operations in the alpine regions of barbary, i should receive in egypt from those illustrious men who had for some months formed the institute of cairo, the same kind attentions with which i had been honoured during my abode in paris. i hastily completed my collection of instruments, and purchased works relating to the countries i was going to visit. i parted from a brother who, by his advice and example, had hitherto exercised a great influence on the direction of my thoughts. he approved the motives which determined me to quit europe; a secret voice assured us that we should meet again; and that hope, which did not prove delusive, assuaged the pain of a long separation. i left paris with the intention of embarking for algiers and egypt; but by one of those vicissitudes which sway the affairs of this life, i returned to my brother from the river amazon and peru, without having touched the continent of africa. the swedish frigate which was to convey m. skioldebrand to algiers, was expected at marseilles toward the end of october. m. bonpland and myself repaired thither with great celerity, for during our journey we were tormented with the fear of being too late, and missing our passage. m. skioldebrand was no less impatient than ourselves to reach his place of destination. several times a day we climbed the mountain of notre dame de la garde, which commands an extensive view of the mediterranean. every sail we descried in the horizon excited in us the most eager emotion; but after two months of anxiety and vain expectation, we learned by the public papers, that the swedish frigate which was to convey us, had suffered greatly in a storm on the coast of portugal, and had been forced to enter the port of cadiz, to refit. this news was confirmed by private letters, assuring us that the jaramas, which was the name of the frigate, would not reach marseilles before the spring. we felt no inclination to prolong our stay in provence till that period. the country, and especially the climate, were delightful, but the aspect of the sea reminded us of the failure of our projects. in an excursion we made to hyeres and toulon, we found in the latter port the frigate la boudeuse, which had been commanded by m. de bougainville, in his voyage round the world. she was then fitting out for corsica. m. de bougainville had honoured me with particular kindness during my stay in paris, when i was preparing to accompany the expedition of captain baudin. i cannot describe the impression made upon my mind by the sight of the vessel which had carried commerson to the islands of the south sea. in some conditions of the mind, a painful emotion blends itself with all our feelings. we still persisted in the intention of visiting the african coast, and were nearly becoming the victims of our perseverance. a small vessel of ragusa, on the point of setting sail for tunis, was at that time in the port of marseilles; we thought the opportunity favourable for reaching egypt and syria, and we agreed with the captain for our passage. the vessel was to sail the following day; but a circumstance trivial in itself happily prevented our departure. the live-stock intended to serve us for food during our passage, was kept in the great cabin. we desired that some changes should be made, which were indispensable for the safety of our instruments; and during this interval we learnt at marseilles, that the government of tunis persecuted the french residing in barbary, and that every person coming from a french port was thrown into a dungeon. having escaped this imminent danger, we were compelled to suspend the execution of our projects. we resolved to pass the winter in spain, in hopes of embarking the next spring, either at carthagena, or at cadiz, if the political situation of the east permitted. we crossed catalonia and the kingdom of valencia, on our way to madrid. we visited the ruins of tarragona and those of ancient saguntum; and from barcelona we made an excursion to montserrat, the lofty peaks of which are inhabited by hermits, and where the contrast between luxuriant vegetation and masses of naked and arid rocks, forms a landscape of a peculiar character. i employed myself in ascertaining by astronomical observations the position of several points important for the geography of spain, and determined by means of the barometer the height of the central plain. i likewise made several observations on the inclination of the needle, and on the intensity of the magnetic forces. on my arrival at madrid i had reason to congratulate myself on the resolution i had formed of visiting the peninsula. baron de forell, minister from the court of saxony, treated me with a degree of kindness, of which i soon felt the value. he was well versed in mineralogy, and was full of zeal for every undertaking that promoted the progress of knowledge. he observed to me, that under the administration of an enlightened minister, don mariano luis de urquijo, i might hope to obtain permission to visit, at my own expense, the interior of spanish america. after the disappointments i had suffered, i did not hesitate a moment to adopt this idea. i was presented at the court of aranjuez in march and the king received me graciously. i explained to him the motives which led me to undertake a voyage to the new world and the philippine islands, and i presented a memoir on the subject to the secretary of state. senor de urquijo supported my demand, and overcame every obstacle. i obtained two passports, one from the first secretary of state, the other from the council of the indies. never had so extensive a permission been granted to any traveller, and never had any foreigner been honoured with more confidence on the part of the spanish government. many considerations might have induced us to prolong our abode in spain. the abbe cavanilles, no less remarkable for the variety of his attainments than his acute intelligence; m. nee, who, together with m. haenke, had, as botanist, made part of the expedition of malaspina, and who had formed one of the greatest herbals ever seen in europe; don casimir ortega, the abbe pourret, and the learned authors of the flora of peru, messrs. ruiz and pavon, all opened to us without reserve their rich collections. we examined part of the plants of mexico, discovered by messrs. sesse, mocino, and cervantes, whose drawings had been sent to the museum of natural history of madrid. this great establishment, the direction of which was confided to senor clavijo, author of an elegant translation of the works of buffon, offered us, it is true, no geological representation of the cordilleras, but m. proust, so well known by the great accuracy of his chemical labours, and a distinguished mineralogist, m. hergen, gave us curious details on several mineral substances of america. it would have been useful to us to have employed a longer time in studying the productions of the countries which were to be the objects of our research, but our impatience to take advantage of the permission given us by the court was too great to suffer us to delay our departure. for a year past, i had experienced so many disappointments, that i could scarcely persuade myself that my most ardent wishes would be at length fulfilled. we left madrid about the middle of may, crossed a part of old castile, the kingdoms of leon and galicia, and reached corunna, whence we were to embark for cuba. the winter having been protracted and severe, we enjoyed during the journey that mild temperature of the spring, which in so southern a latitude usually occurs during march and april. the snow still covered the lofty granitic tops of the guadarama; but in the deep valleys of galicia, which resemble the most picturesque spots of switzerland and the tyrol, cistuses loaded with flowers; and arborescent heaths clothed every rock. we quitted without regret the elevated plain of the two castiles, which is everywhere devoid of vegetation, and where the severity of the winter's cold is followed by the overwhelming heat of summer. from the few observations i personally made, the interior of spain forms a vast plain, elevated three hundred toises (five hundred and eighty-four metres) above the level of the ocean, is covered with secondary formations, grit-stone, gypsum, sal-gem, and the calcareous stone of jura. the climate of the castiles is much colder than that of toulon and genoa; its mean temperature scarcely rises to degrees of the centigrade thermometer. we are astonished to find that, in the latitude of calabria, thessaly, and asia minor, orange-trees do not flourish in the open air. the central elevated plain is encircled by a low and narrow zone, where the chamaerops, the date-tree, the sugar-cane, the banana, and a number of plants common to spain and the north of africa, vegetate on several spots, without suffering from the rigours of winter. from the th to th degrees of latitude, the medium temperature of this zone is from to degrees; and by a concurrence of circumstances, which it would be too long to explain, this favoured region has become the principal seat of industry and intellectual improvement. when, in the kingdom of valencia, we ascend from the shore of the mediterranean towards the lofty plains of la mancha and the castiles, we seem to discern, far inland, from the lengthened declivities, the ancient coast of the peninsula. this curious phenomenon recalls the traditions of the samothracians, and other historical testimonies, according to which it is supposed that the irruption of the waters through the dardanelles, augmenting the basin of the mediterranean, rent and overflowed the southern part of europe. if we admit that these traditions owe their origin, not to mere geological reveries, but to the remembrance of some ancient catastrophe, we may conceive the central elevated plain of spain resisting the efforts of these great inundations, till the draining of the waters, by the straits formed between the pillars of hercules, brought the mediterranean progressively to its present level, lower egypt emerging above its surface on the one side, and the fertile plains of tarragona, valencia, and murcia, on the other. everything that relates to the formation of that sea,* (* some of the ancient geographers believed that the mediterranean, swelled by the waters of the euxine, the palus maeotis, the caspian sea, and the sea of aral, had broken the pillars of hercules; others admitted that the irruption was made by the waters of the ocean. in the first of these hypotheses, the height of the land between the black sea and the baltic, and between the ports of cette and bordeaux, determine the limit which the accumulation of the waters may have reached before the junction of the black sea, the mediterranean, and the atlantic, as well to the north of the dardanelles, as to the east of this strip of land which formerly joined europe to mauritania, and of which, in the time of strabo, certain vestiges remained in the islands of juno and the moon.) which has had so powerful an influence on the first civilization of mankind, is highly interesting. we might suppose, that spain, forming a promontory amidst the waves, was indebted for its preservation to the height of its land; but in order to give weight to these theoretic ideas, we must clear up the doubts that have arisen respecting the rupture of so many transverse dikes;--we must discuss the probability of the mediterranean having been formerly divided into several separate basins, of which sicily and the island of candia appear to mark the ancient limits. we will not here risk the solution of these problems, but will satisfy ourselves in fixing attention on the striking contrast in the configuration of the land in the eastern and western extremities of europe. between the baltic and the black sea, the ground is at present scarcely fifty toises above the level of the ocean, while the plain of la mancha, if placed between the sources of the niemen and the borysthenes, would figure as a group of mountains of considerable height. if the causes, which may have changed the surface of our planet, be an interesting speculation, investigations of the phenomena, such as they offer themselves to the measures and observations of the naturalist, lead to far greater certainty. from astorga to corunna, especially from lugo, the mountains rise gradually. the secondary formations gently disappear, and are succeeded by the transition rocks, which indicate the proximity of primitive strata. we found considerable mountains composed of that ancient grey stone which the mineralogists of the school of freyberg name grauwakke, and grauwakkenschiefer. i do not know whether this formation, which is not frequent in the south of europe, has hitherto been discovered in other parts of spain. angular fragments of lydian stone, scattered along the valleys, seemed to indicate that the transition schist is the basis of the strata of greywacke. near corunna even granitic ridges stretch as far as cape ortegal. these granites, which seem formerly to have been contiguous to those of britanny and cornwall, are perhaps the wrecks of a chain of mountains destroyed and sunk in the waves. large and beautiful crystals of feldspar characterise this rock. common tin ore is sometimes discovered there, but working the mines is a laborious and unprofitable operation for the inhabitants of galicia. the first secretary of state had recommended us very particularly to brigadier don raphael clavijo, who was employed in forming new dock-yards at corunna. he advised us to embark on board the sloop pizarro,* (* according to the spanish nomenclature, the pizarro was a light frigate (fragata lijera).) which was to sail in company with the alcudia, the packet-boat of the month of may, which, on account of the blockade, had been detained three weeks in the port. senor clavijo ordered the necessary arrangements to be made on board the sloop for placing our instruments, and the captain of the pizarro received orders to stop at teneriffe, as long as we should judge necessary to enable us to visit the port of orotava, and ascend the peak. we had yet ten days to wait before we embarked. during this interval, we employed ourselves in preparing the plants we had collected in the beautiful valleys of galicia, which no naturalist had yet visited: we examined the fuci and the mollusca which the north-west winds had cast with great profusion at the foot of the steep rock, on which the lighthouse of the tower of hercules is built. this edifice, called also the iron tower, was repaired in . it is ninety-two feet high, its walls are four feet and a half thick, and its construction clearly proves that it was built by the romans. an inscription discovered near its foundation, a copy of which m. laborde obligingly gave me, informs us, that this pharos was constructed by caius sevius lupus, architect of the city of aqua flavia (chaves), and that it was dedicated to mars. why is the iron tower called in the country by the name of hercules? was it built by the romans on the ruins of a greek or phoenician edifice? strabo, indeed, affirms that galicia, the country of the callaeci, had been peopled by greek colonies. according to an extract from the geography of spain, by asclepiades the myrlaean, an ancient tradition stated that the companions of hercules had settled in these countries. the ports of ferrol and corunna both communicate with one bay, so that a vessel driven by bad weather towards the coast may anchor in either, according to the wind. this advantage is invaluable where the sea is almost always tempestuous, as between capes ortegal and finisterre, which are the promontories trileucum and artabrum of ancient geography. a narrow passage, flanked by perpendicular rocks of granite, leads to the extensive basin of ferrol. no port in europe has so extraordinary an anchorage, from its very inland position. the narrow and tortuous passage by which vessels enter this port, has been opened, either by the irruption of the waves, or by the reiterated shocks of very violent earthquakes. in the new world, on the coasts of new andalusia, the laguna del obispo (bishop's lake) is formed exactly like the port of ferrol. the most curious geological phenomena are often repeated at immense distances on the surface of continents; and naturalists who have examined different parts of the globe, are struck with the extreme resemblance observed in the rents on coasts, in the sinuosities of the valleys, in the aspect of the mountains, and in their distribution by groups. the accidental concurrence of the same causes must have everywhere produced the same effects; and amidst the variety of nature, an analogy of structure and form is observed in the arrangement of inanimate matter, as well as in the internal organization of plants and of animals. crossing from corunna to ferrol, over a shallow, near the white signal, in the bay, which according to d'anville is the portus magnus of the ancients, we made several experiments by means of a valved thermometrical sounding lead, on the temperature of the ocean, and on the decrement of caloric in the successive strata of water. the thermometer on the bank, and near the surface, was from . to . degrees centigrades, while in deep water it constantly marked or . degrees, the air being at . degrees. the celebrated franklin and mr. jonathan williams* (* author of a work entitled "thermometrical navigation," published at philadelphia.) were the first to invite the attention of naturalists to the phenomena of the temperature of the atlantic over shoals, and in that zone of tepid and flowing waters which runs from the gulf of mexico to the banks of newfoundland and the northern coasts of europe. the observation, that the proximity of a sand-bank is indicated by a rapid descent of the temperature of the sea at its surface, is not only interesting to the naturalist, but may become also very important for the safety of navigators. the use of the thermometer ought certainly not to lead us to neglect the use of the lead; but experiments sufficiently prove, that variations of temperature, sensible to the most imperfect instruments, indicate danger long before the vessel reaches the shoals. in such cases, the frigidity of the water may induce the pilot to heave the lead in places where he thought himself in the most perfect safety. the waters which cover the shoals owe in a great measure the diminution of their temperature to their mixture with the lower strata of water, which rise towards the surface on the edge of the banks. the moment of leaving europe for the first time is attended with a solemn feeling. we in vain summon to our minds the frequency of the communication between the two worlds; we in vain reflect on the great facility with which, from the improved state of navigation, we traverse the atlantic, which compared to the pacific is but a larger arm of the sea; the sentiment we feel when we first undertake so distant a voyage is not the less accompanied by a deep emotion, unlike any other impression we have hitherto felt. separated from the objects of our dearest affections, entering in some sort on a new state of existence, we are forced to fall back on our own thoughts, and we feel within ourselves a dreariness we have never known before. among the letters which, at the time of our embarking, i wrote to friends in france and germany, one had a considerable influence on the direction of our travels, and on our succeeding operations. when i left paris with the intention of visiting the coast of africa, the expedition for discoveries in the pacific seemed to be adjourned for several years. i had agreed with captain baudin, that if, contrary to his expectation, his voyage took place at an earlier period, and intelligence of it should reach me in time, i would endeavour to return from algiers to a port in france or spain, to join the expedition. i renewed this promise on leaving europe, and wrote to m. baudin, that if the government persisted in sending him by cape horn, i would endeavour to meet him either at monte video, chile, or lima, or wherever he should touch in the spanish colonies. in consequence of this engagement, i changed the plan of my journey, on reading in the american papers, in , that the french expedition had sailed from havre, to circumnavigate the globe from east to west. i hired a small vessel from batabano, in the island of cuba, to portobello, and thence crossed the isthmus to the coast of the pacific; this mistake of a journalist led m. bonpland and myself to travel eight hundred leagues through a country we had no intention to visit. it was only at quito, that a letter from m. delambre, perpetual secretary of the first class of the institute, informed us, that captain baudin went by the cape of good hope, without touching on the eastern or western coasts of america. we spent two days at corunna, after our instruments were embarked. a thick fog, which covered the horizon, at length indicated the change of weather we so anxiously desired. on the th of june, in the evening, the wind turned to north-east, a point which, on the coast of galicia, is considered very constant during the summer. the pizarro prepared to sail on the th, though we had intelligence that only a few hours previously an english squadron had been seen from the watch-tower of sisarga, appearing to stand towards the mouth of the tagus. those who saw our ship weigh anchor asserted that we should be captured in three days, and that, forced to follow the fate of the vessel, we should be carried to lisbon. this prognostic gave us the more uneasiness, as we had known some mexicans at madrid, who, in order to return to vera cruz, had embarked three times at cadiz, and having been each time taken at the entrance of the port, were at length obliged to return to spain through portugal. the pizarro set sail at two in the afternoon. as the long and narrow passage by which a ship sails from the port of corunna opens towards the north, and the wind was contrary, we made eight short tacks, three of which were useless. a fresh tack was made, but very slowly, and we were for some moments in danger at the foot of fort st. amarro, the current having driven us very near the rock, on which the sea breaks with considerable violence. we remained with our eyes fixed on the castle of st. antonio, where the unfortunate malaspina was then a captive in a state prison. on the point of leaving europe to visit the countries which this illustrious traveller had visited with so much advantage, i could have wished to have fixed my thoughts on some object less affecting. at half-past six we passed the tower of hercules, which is the lighthouse of corunna, as already mentioned, and where, from a very remote time, a coal-fire has been kept up for the direction of vessels. the light of this fire is in no way proportionate to the noble construction of so vast an edifice, being so feeble that ships cannot perceive it till they are in danger of striking on the shore. towards the close of day the wind increased and the sea ran high. we directed our course to north-west, in order to avoid the english frigates, which we supposed were cruising off these coasts. about nine we spied the light of a fishing-hut at sisarga, which was the last object we beheld in the west of europe. on the th we were in the latitude of cape finisterre. the group of granitic rocks, which forms part of this promontory, like that of torianes and monte de corcubion, bears the name of the sierra de torinona. cape finisterre is lower than the neighbouring lands, but the torinona is visible at seventeen leagues' distance, which proves that the elevation of its highest summit is not less than toises ( metres). spanish navigators affirm that on these coasts the magnetic variation differs extremely from that observed at sea. m. bory, it is true, in the voyage of the sloop amaranth, found in , that the variation of the needle determined at the cape was four degrees less than could have been conjectured from the observations made at the same period along the coasts. in the same manner as the granite of galicia contains tin disseminated in its mass, that of cape finisterre probably contains micaceous iron. in the mountains of the upper palatinate there are granitic rocks in which crystals of micaceous iron take the place of common mica. on the th, at sunset, we descried from the mast-head an english convoy sailing along the coast, and steering towards south-east. in order to avoid it we altered our course during the night. from this moment no light was permitted in the great cabin, to prevent our being seen at a distance. this precaution, which was at the time prescribed in the regulations of the packet-ships of the spanish navy, was extremely irksome to us during the voyages we made in the course of the five following years. we were constantly obliged to make use of dark-lanterns to examine the temperature of the water, or to read the divisions on the limb of the astronomical instruments. in the torrid zone, where twilight lasts but a few minutes, our operations ceased almost at six in the evening. this state of things was so much the more vexatious to me as from the nature of my constitution i never was subject to sea-sickness, and feel an extreme ardour for study during the whole time i am at sea. on the th of june, in latitude degrees minutes, and longitude degrees minutes west of the meridian of the observatory of paris, we began to feel the effects of the great current which from the azores flows towards the straits of gibraltar and the canary islands. this current is commonly attributed to that tendency towards the east, which the straits of gibraltar give to the waters of the atlantic ocean. m. de fleurieu observes that the mediterranean, losing by evaporation more water than the rivers can supply, causes a movement in the neighbouring ocean, and that the influence of the straits is felt at the distance of six hundred leagues. without derogating from the respect i entertain for the opinion of that celebrated navigator, i may be permitted to consider this important object in a far more general point of view. when we cast our eyes over the atlantic, or that deep valley which divides the western coasts of europe and africa from the eastern coasts of the new world, we distinguish a contrary direction in the motion of the waters. within the tropics, especially from the coast of senegal to the caribbean sea, the general current, that which was earliest known to mariners, flows constantly from east to west. this is called the equinoctial current. its mean rapidity, corresponding to different latitudes, is nearly the same in the atlantic and in the pacific, and may be estimated at nine or ten miles in twenty-four hours, consequently from . to . of a foot every second! in those latitudes the waters run towards the west with a velocity equal to a fourth of the rapidity of the greater part of the larger rivers of europe. the movement of the ocean in a direction contrary to that of the rotation of the globe, is probably connected with this last phenomenon only as far as the rotation converts into trade winds* (* the limits of the trade winds were, for the first time, determined by dampier in .) the polar winds, which, in the low regions of the atmosphere bring back the cold air of the high latitudes toward the equator. to the general impulsion which these trade-winds give the surface of the sea, we must attribute the equinoctial current, the force and rapidity of which are not sensibly modified by the local variations of the atmosphere. in the channel which the atlantic has dug between guiana and guinea, on the meridian of or degrees, and from the th or th to the nd or rd degrees of northern latitude, where the trade-winds are often interrupted by winds blowing from the south and south-south-west, the equinoctial current is more inconstant in its direction. towards the coasts of africa, vessels are drawn in the direction of south-east; whilst towards the bay of all saints and cape st. augustin, the coasts of which are dreaded by navigators sailing towards the mouth of the plata, the general motion of the waters is masked by a particular current (the effects of which extend from cape st. roche to the isle of trinidad) running north-west with a mean velocity of a foot and a half every second. the equinoctial current is felt, though feebly, even beyond the tropic of cancer, in the th and th degrees of latitude. in the vast basin of the atlantic, at six or seven hundred leagues from the coasts of africa, vessels from europe bound to the west indies, find their sailing accelerated before they reach the torrid zone. more to the north, in and degrees, between the parallels of teneriffe and ceuta, in and degrees of longitude, no constant motion is observed: there, a zone of leagues in breadth separates the equinoctial current (the tendency of which is towards the west) from that great mass of water which runs eastward, and is distinguished for its extraordinary high temperature. to this mass of waters, known by the name of the gulf-stream,* (* sir francis drake observed this extraordinary movement of the waters, but he was unacquainted with their high temperature.) the attention of naturalists was directed in by the curious observations of franklin and sir charles blagden. the equinoctial current drives the waters of the atlantic towards the coasts inhabited by the mosquito indians, and towards the shores of honduras. the new continent, stretching from south to north, forms a sort of dyke to this current. the waters are carried at first north-west, and passing into the gulf of mexico through the strait formed by cape catoche and cape st. antonio, follow the bendings of the mexican coast, from vera cruz to the mouth of the rio del norte, and thence to the mouths of the mississippi, and the shoals west of the southern extremity of florida. having made this vast circuit west, north, east, and south, the current takes a new direction northward, and throws itself with impetuosity into the gulf of florida. at the end of the gulf of florida, in the parallel of cape cannaveral, the gulf-stream, or current of florida, runs north-east. its rapidity resembles that of a torrent, and is sometimes five miles an hour. the pilot may judge, with some certainty, of the proximity of his approach to new york, philadelphia, or charlestown when he reaches the edge of the stream; for the elevated temperature of the waters, their saltness, indigo-blue colour, and the shoals of seaweed which cover their surface, as well as the heat of the surrounding atmosphere, all indicate the gulf-stream. its rapidity diminishes towards the north, at the same time that its breadth increases and the waters become cool. between cayo biscaino and the bank of bahama the breadth is only leagues, whilst in the latitude of / degrees, it is , and in the parallel of charlestown, opposite cape henlopen, from to leagues. the rapidity of the current is from three to five miles an hour where the stream is narrowest, and is only one mile as it advances towards the north. the waters of the mexican gulf; forcibly drawn to north-east, preserve their warm temperature to such a point, that in and degrees of latitude i found them at . degrees ( degrees r.) when, out of the current, the heat of the ocean at its surface was scarcely . degrees ( degrees r.). in the parallel of new york and oporto, the temperature of the gulf-stream is consequently equal to that of the seas of the tropics in the th degree of latitude, as, for instance, in the parallel of porto rico and the islands of cape verd. to the east of the port of boston, and on the meridian of halifax, in latitude degrees minutes, and longitude degrees, the current is near leagues broad. from this point it turns suddenly to the east, so that its western edge, as it bends, becomes the western limit of the running waters, skirting the extremity of the great bank of newfoundland, which m. volney ingeniously calls the bar of the mouth of this enormous sea-river. the cold waters of this bank, which according to my experiments are at a temperature of . or degrees ( or degrees r.) present a striking contrast with the waters of the torrid zone, driven northward by the gulf-stream, the temperature of which is from to . degrees ( to degrees r.). in these latitudes, the caloric is distributed in a singular manner throughout the ocean; the waters of the bank are . degrees colder than the neighbouring sea; and this sea is degrees colder than the current. these zones can have no equilibrium of temperature, having a source of heat, or a cause of refrigeration, which is peculiar to each, and the influence of which is permanent. from the bank of newfoundland, or from the nd degree of longitude to the azores, the gulf-stream continues its course to east and east-south-east. the waters are still acted upon by the impulsion they received near a thousand leagues distance, in the straits of florida, between the island of cuba and the shoals of tortoise island. this distance is double the length of the course of the river amazon, from jaen or the straits of manseriche to grand para. on the meridian of the islands of corvo and flores, the most western of the group of the azores, the breadth of the current is leagues. when vessels, on their return from south america to europe, endeavour to make these two islands to rectify their longitude, they are always sensible of the motion of the waters to south-east. at the rd degree of latitude the equinoctial current of the tropics is in the near vicinity of the gulf-stream. in this part of the ocean, we may in a single day pass from waters that flow towards the west, into those which run to the south-east or east-south-east. from the azores, the current of florida turns towards the straits of gibraltar, the isle of madeira, and the group of the canary islands. the opening of the pillars of hercules has no doubt accelerated the motion of the waters towards the east. we may in this point of view assert, that the strait, by which the mediterranean communicates with the atlantic, produces its effects at a great distance; but it is probable also, that, without the existence of this strait, vessels sailing to teneriffe would be driven south-east by a cause which we must seek on the coasts of the new world. every motion is the cause of another motion in the vast basin of the seas as well as in the aerial ocean. tracing the currents to their most distant sources, and reflecting on their variable celerity, sometimes decreasing as between the gulf of florida and the bank of newfoundland; at other times augmenting, as in the neighbourhood of the straits of gibraltar, and near the canary islands, we cannot doubt but the same cause which impels the waters to make the circuitous sweep of the gulf of mexico, agitates them also near the island of madeira. on the south of that island, we may follow the current, in its direction south-east and south-south-east towards the coast of africa, between cape cantin and cape bojador. in those latitudes a vessel becalmed is running on the coast, while, according to the uncorrected reckoning, it was supposed to be a good distance out at sea. were the motion of the waters caused by the opening at the straits of gibraltar, why, on the south of those straits, should it not follow an opposite direction? on the contrary, in the th and th degrees of latitude, the current flows at first direct south, and then south-west. cape blanc, which, after cape verd, is the most salient promontory, seems to have an influence on this direction, and in this parallel the waters, of which we have followed the course from the coasts of honduras to those of africa, mingle with the great current of the tropics to resume their tour from east to west. several hundred leagues westward of the canary islands, the motion peculiar to the equinoctial waters is felt in the temperate zone from the th and th degrees of north latitude; but on the meridian of the island of ferro, vessels sail southward as far as the tropic of cancer, before they find themselves, by their reckoning, eastward of their right course.* (* see humboldt's cosmos volume page bohn's edition.) we have just seen that between the parallels of and degrees, the waters of the atlantic are driven by the currents in a continual whirlpool. supposing that a molecule of water returns to the same place from which it departed, we can estimate, from our present knowledge of the swiftness of currents, that this circuit of leagues is not terminated in less than two years and ten months. a boat, which may be supposed to receive no impulsion from the winds, would require thirteen months to go from the canary islands to the coast of caracas, ten months to make the tour of the gulf of mexico and reach tortoise shoals opposite the port of the havannah, while forty or fifty days might be sufficient to carry it from the straits of florida to the bank of newfoundland. it would be difficult to fix the rapidity of the retrograde current from this bank to the shores of africa; estimating the mean velocity of the waters at seven or eight miles in twenty-four hours, we may allow ten or eleven months for this last distance. such are the effects of the slow but regular motion which agitates the waters of the atlantic. those of the river amazon take nearly forty-five days to flow from tomependa to grand para. a short time before my arrival at teneriffe, the sea had left in the road of santa cruz the trunk of a cedrela odorata covered with the bark. this american tree vegetates within the tropics, or in the neighbouring regions. it had no doubt been torn up on the coast of the continent, or of that of honduras. the nature of the wood, and the lichens which covered its bark, bore evidence that this trunk had not belonged to these submarine forests which ancient revolutions of the globe have deposited in the polar regions. if the cedrela, instead of having been cast on the strand of teneriffe, had been carried farther south, it would probably have made the whole tour of the atlantic, and returned to its native soil with the general current of the tropics. this conjecture is supported by a fact of more ancient date, recorded in the history of the canaries by the abbe viera. in , a small vessel laden with corn, and bound from the island of lancerota, to santa cruz, in teneriffe, was driven out to sea, while none of the crew were on board. the motion of the waters from east to west, carried it to america, where it went on shore at la guayra, near caracas. whilst the art of navigation was yet in its infancy, the gulf-stream suggested to the mind of christopher columbus certain indications of the existence of western regions. two corpses, the features of which indicated a race of unknown men, were cast ashore on the azores, towards the end of the th century. nearly at the same period, the brother-in-law of columbus, peter correa, governor of porto santo, found on the strand of that island pieces of bamboo of extraordinary size, brought thither by the western currents. the dead bodies and the bamboos attracted the attention of the genoese navigator, who conjectured that both came from a continent situate towards the west. we now know that in the torrid zone the trade-winds and the current of the tropics are in opposition to every motion of the waves in the direction of the earth's rotation. the productions of the new world cannot reach the old but by the very high latitudes, and in following the direction of the current of florida. the fruits of several trees of the antilles are often washed ashore on the coasts of the islands of ferro and gomera. before the discovery of america, the canarians considered these fruits as coming from the enchanted isle of st. borondon, which according to the reveries of pilots, and certain legends, was situated towards the west in an unknown part of the ocean, buried, as was supposed, in eternal mists. my chief view in tracing a sketch of the currents of the atlantic is to prove that the motion of the waters towards the south-east, from cape st. vincent to the canary islands, is the effect of the general motion to which the surface of the ocean is subjected at its western extremity. we shall give but a very succinct account of the arm of the gulf-stream, which in the th and th degrees of latitude, near the bank called the bonnet flamand, runs from south-west to north-east towards the coasts of europe. this partial current becomes very strong at those times when the west winds are of long continuance: and, like that which flows along the isles of ferro and gomera, it deposits every year on the western coasts of ireland and norway the fruit of trees which belong to the torrid zone of america. on the shores of the hebrides, we collect seeds of mimosa scandens, of dolichos urens, of guilandina bonduc, and several other plants of jamaica, the isle of cuba, and of the neighbouring continent. the current carries thither also barrels of french wine, well preserved, the remains of the cargoes of vessels wrecked in the west indian seas. to these examples of the distant migration of the vegetable world, others no less striking may be added. the wreck of an english vessel, the tilbury, burnt near jamaica, was found on the coast of scotland. on these same coasts are sometimes found various kinds of tortoises, that inhabit the waters of the antilles. when the western winds are of long duration, a current is formed in the high latitudes, which runs directly towards east-south-east, from the coasts of greenland and labrador, as far as the north of scotland. wallace relates, that twice (in and ), american savages of the race of the esquimaux, driven out to sea in their leathern canoes, during a storm, and left to the guidance of the currents, reached the orkneys. this last example is the more worthy of attention, as it proves at the same time how, at a period when the art of navigation was yet in its infancy, the motion of the waters of the ocean may have contributed to disseminate the different races of men over the face of the globe. in reflecting on the causes of the atlantic currents, we find that they are much more numerous than is generally believed; for the waters of the sea may be put in motion by an external impulse, by difference of heat and saltness, by the periodical melting of the polar ice, or by the inequality of evaporation, in different latitudes. sometimes several of these causes concur to one and the same effect, and sometimes they produce several contrary effects. winds that are light, but which, like the trade-winds, are continually acting on the whole of a zone, cause a real movement of transition, which we do not observe in the heaviest tempests, because these last are circumscribed within a small space. when, in a great mass of water, the particles at the surface acquire a different specific gravity, a superficial current is formed, which takes its direction towards the point where the water is coldest, or where it is most saturated with muriate of soda, sulphate of lime, and muriate or sulphate of magnesia. in the seas of the tropics we find, that at great depths the thermometer marks or centesimal degrees. such is the result of the numerous experiments of commodore ellis and of m. peron. the temperature of the air in those latitudes being never below or degrees, it is not at the surface that the waters can have acquired a degree of cold so near the point of congelation, and of the maximum of the density of water. the existence of this cold stratum in the low latitudes is an evident proof of the existence of an under-current, which runs from the poles towards the equator: it also proves that the saline substances which alter the specific gravity of the water, are distributed in the ocean, so as not to annihilate the effect produced by the differences of temperature. considering the velocity of the molecules, which, on account of the rotatory motion of the globe, vary with the parallels, we may be tempted to admit that every current, in the direction from south to north, tends at the same time eastward, while the waters which run from the pole towards the equator, have a tendency to deviate westward. we may also be led to think that these tendencies diminish to a certain point the speed of the tropical current, in the same manner as they change the direction of the polar current, which in july and august, is regularly perceived during the melting of the ice, on the parallel of the bank of newfoundland, and farther north. very old nautical observations, which i have had occasion to confirm by comparing the longitude given by the chronometer with that which the pilots obtained by their reckoning, are, however, contrary to these theoretical ideas. in both hemispheres, the polar currents, when they are perceived, decline a little to the east; and it would seem that the cause of this phenomenon should be sought in the constancy of the westerly winds which prevail in the high latitudes. besides, the particles of water do not move with the same rapidity as the particles of air; and the currents of the ocean, which we consider as most rapid, have only a swiftness of eight or nine feet a second; it is consequently very probable, that the water, in passing through different parallels, gradually acquires a velocity correspondent to those parallels, and that the rotation of the earth does not change the direction of the currents. the variable pressure on the surface of the sea, caused by the changes in the weight of the air, is another cause of motion which deserves particular attention. it is well known, that the barometric variations do not in general take place at the same moment in two distant points, which are on the same level. if in one of these points the barometer stands a few lines lower than in the other, the water will rise where it finds the least pressure of air, and this local intumescence will continue, till, from the effect of the wind, the equilibrium of the air is restored. m. vaucher thinks that the tides in the lake of geneva, known by the name of the seiches, arise from the same cause. we know not whether it be the same, when the movement of progression, which must not be confounded with the oscillation of the waves, is the effect of an external impulse. m. de fleurieu, in his narrative of the voyage of the isis, cites several facts, which render it probable that the sea is not so still at the bottom as naturalists generally suppose. without entering here into a discussion of this question, we shall only observe that, if the external impulse is constant in its action, like that of the trade-winds, the friction of the particles of water on each other must necessarily propagate the motion of the surface of the ocean even to the lower strata; and in fact this propagation in the gulf-stream has long been admitted by navigators, who think they discover the effects in the great depth of the sea wherever it is traversed by the current of florida, even amidst the sand-banks which surround the northern coasts of the united states. this immense river of hot waters, after a course of fifty days, from the th to the th degree of latitude, or leagues, does not lose, amidst the rigours of winter in the temperate zone, more than or degrees of the temperature it had under the tropics. the greatness of the mass, and the small conductibility of water for heat, prevent a more speedy refrigeration. if, therefore, the gulf-stream has dug a channel at the bottom of the atlantic ocean, and if its waters are in motion to considerable depths, they must also in their inferior strata keep up a lower temperature than that observed in the same parallel, in a part of the sea which has neither currents nor deep shoals. these questions can be cleared up only by direct experiments, made by thermometrical soundings. sir erasmus gower remarks, that, in the passage from england to the canary islands, the current, which carries vessels towards the south-east, begins at the th degree of latitude. during our voyage from corunna to the coast of south america, the effect of this motion of the waters was perceived farther north. from the th to the th degree, the deviation was very unequal; the daily average effect was miles, that is, our sloop drove towards the east miles in six days. in crossing the parallel of the straits of gibraltar, at a distance of leagues, we had occasion to observe, that in those latitudes the maximum of the rapidity does not correspond with the mouth of the straits, but with a more northerly point, which lies on the prolongation of a line passing through the strait and cape st. vincent. this line is parallel to the direction which the waters follow from the azores to cape cantin. we should moreover observe (and this fact is not uninteresting to those who examine the nature of fluids), that in this part of the retrograde current, on a breadth of or leagues, the whole mass of water has not the same rapidity, nor does it follow precisely the same direction. when the sea is perfectly calm, there appears at the surface narrow stripes, like small rivulets, in which the waters run with a murmur very sensible to the ear of an experienced pilot. on the th of june, in degrees minutes north latitude, we found ourselves in the midst of a great number of these beds of currents. we took their direction with the compass, and some ran north-east, others east-north-east, though the general movement of the ocean, indicated by comparing the reckoning with the chronometrical longitude, continued to be south-east. it is very common to see a mass of motionless waters crossed by threads of water, which run in different directions, and we may daily observe this phenomenon on the surface of lakes; but it is much less frequent to find partial movements, impressed by local causes on small portions of waters in the midst of an oceanic river, which occupies an immense space, and which moves, though slowly, in a constant direction. in the conflict of currents, as in the oscillation of the waves, our imagination is struck by those movements which seem to penetrate each other, and by which the ocean is continually agitated. we passed cape st. vincent, which is of basaltic formation, at the distance of more than eighty leagues. it is not distinctly seen at a greater distance than leagues, but the granitic mountain called the foya de monchique, situated near the cape, is perceptible, as pilots allege, at the distance of leagues. if this assertion be exact, the foya is toises ( metres), and consequently toises ( metres) higher than vesuvius. from corunna to the th degree of latitude we had scarcely seen any organic being, excepting sea-swallows and a few dolphins. we looked in vain for sea-weeds (fuci) and mollusca, when on the th of june we were struck with a curious sight which afterwards was frequently renewed in the southern ocean. we entered on a zone where the whole sea was covered with a prodigious quantity of medusas. the vessel was almost becalmed, but the mollusca were borne towards the south-east, with a rapidity four times greater than the current. their passage lasted near three quarters of an hour. we then perceived but a few scattered individuals, following the crowd at a distance as if tired with their journey. do these animals come from the bottom of the sea, which is perhaps in these latitudes some thousand fathoms deep? or do they make distant voyages in shoals? we know that the mollusca haunt banks; and if the eight rocks, near the surface, which captain vobonne mentions having seen in , to the north of porto santo, really exist, we may suppose that this innumerable quantity of medusas had been thence detached; for we were but leagues from the reef. we found, beside the medusa aurita of baster, and the medusa pelagica of bosc with eight tentacula (pelagia denticulata, peron), a third species which resembles the medusa hysocella, and which vandelli found at the mouth of the tagus. it is known by its brownish-yellow colour, and by its tentacula, which are longer than the body. several of these sea-nettles were four inches in diameter: their reflection was almost metallic: their changeable colours of violet and purple formed an agreeable contrast with the azure tint of the ocean. in the midst of these medusas m. bonpland observed bundles of dagysa notata, a mollusc of a singular construction, which sir joseph banks first discovered. these are small gelatinous bags, transparent, cylindrical, sometimes polygonal, thirteen lines long and two or three in diameter. these bags are open at both ends. in one of these openings, we observed a hyaline bladder, marked with a yellow spot. the cylinders lie longitudinally, one against another, like the cells of a bee-hive, and form chaplets from six to eight inches in length. i tried the galvanic electricity on these mollusca, but it produced no contraction. it appears that the genus dagysa, formed at the time of cook's first voyage, belongs to the salpas (biphores of bruguiere), to which m. cuvier joins the thalia of brown, and the tethys vagina of tilesius. the salpas journey also by groups, joining in chaplets, as we have observed of the dagysa. on the morning of the th of june, in degrees minutes latitude, we saw large masses of this last mollusc in its passage, the sea being perfectly calm. we observed during the night, that, of three species of medusas which we collected, none yielded any light but at the moment of a very slight shock. this property does not belong exclusively to the medusa noctiluca, which forskael has described in his fauna aegyptiaca, and which gmelin has applied to the medusa pelagica of loefling, notwithstanding its red tentacula, and the brownish tuberosities of its body. if we place a very irritable medusa on a pewter plate, and strike against the plate with any sort of metal, the slight vibrations of the plate are sufficient to make this animal emit light. sometimes, in galvanising the medusa, the phosphorescence appears at the moment that the chain closes, though the exciters are not in immediate contact with the organs of the animal. the fingers with which we touch it remain luminous for two or three minutes, as is observed in breaking the shell of the pholades. if we rub wood with the body of a medusa, and the part rubbed ceases shining, the phosphorescence returns if we pass a dry hand over the wood. when the light is extinguished a second time, it can no longer be reproduced, though the place rubbed be still humid and viscous. in what manner ought we to consider the effect of the friction, or that of the shock? this is a question of difficult solution. is it a slight augmentation of temperature which favours the phosphorescence? or does the light return, because the surface is renewed, by putting the animal parts proper to disengage the phosphoric hydrogen in contact with the oxygen of the atmospheric air? i have proved by experiments published in , that the shining of wood is extinguished in hydrogen gas, and in pure azotic gas, and that its light reappears whenever we mix with it the smallest bubble of oxygen gas. these facts, to which several others may be added, tend to explain the causes of the phosphorescence of the sea, and of that peculiar influence which the shock of the waves exercises on the production of light. when we were between the island of madeira and the coast of africa, we had slight breezes and dead calms, very favourable for the magnetic observations, which occupied me during this passage. we were never weary of admiring the beauty of the nights; nothing can be compared to the transparency and serenity of an african sky. we were struck with the innumerable quantity of falling stars, which appeared at every instant. the farther progress we made towards the south, the more frequent was this phenomenon, especially near the canaries. i have observed during my travels, that these igneous meteors are in general more common and luminous in some regions of the globe than in others; but i have never beheld them so multiplied as in the vicinity of the volcanoes of the province of quito, and in that part of the pacific ocean which bathes the volcanic coasts of guatimala. the influence which place, climate, and season appear to exercise on the falling stars, distinguishes this class of meteors from those to which we trace stones that drop from the sky (aerolites), and which probably exist beyond the boundaries of our atmosphere. according to the observations of messrs. benzenberg and brandes, many of the falling stars seen in europe have been only thirty thousand toises high. one was even measured which did not exceed fourteen thousand toises, or five nautical leagues. these measures, which can give no result but by approximation, deserve well to be repeated. in warm climates, especially within the tropics, falling stars leave a tail behind them, which remains luminous or seconds: at other times they seem to burst into sparks, and they are generally lower than those in the north of europe. we perceive them only in a serene and azure sky; they have perhaps never been below a cloud. falling stars often follow the same direction for several hours, which direction is that of the wind. in the bay of naples, m. gay-lussac and myself observed luminous phenomena very analogous to those which fixed my attention during a long abode at mexico and quito. these meteors are perhaps modified by the nature of the soil and the air, like certain effects of the looming or mirage, and of the terrestrial refraction peculiar to the coasts of calabria and sicily. when we were forty leagues east of the island of madeira, a swallow* (* hirundo rustica, linn.) perched on the topsail-yard. it was so fatigued, that it suffered itself to be easily taken. it was remarkable that a bird, in that season, and in calm weather, should fly so far. in the expedition of d'entrecasteaux, a common swallow was seen leagues distant from cape blanco; but this was towards the end of october, and m. labillardiere thought it had newly arrived from europe. we crossed these latitudes in june, at a period when the seas had not for a long time been agitated by tempests. i mention this last circumstance, because small birds and even butterflies, are sometimes forced out to sea by the impetuosity of the winds, as we observed in the pacific ocean, when we were on the western coast of mexico. the pizarro had orders to touch at the isle of lancerota, one of the seven great canary islands; and at five in the afternoon of the th of june, that island appeared so distinctly in view that i was able to take the angle of altitude of a conic mountain, which towered majestically over the other summits, and which we thought was the great volcano which had occasioned such devastation on the night of the st of september, . the current drew us toward the coast more rapidly than we wished. as we advanced, we discovered at first the island of forteventura, famous for its numerous camels;* (* these camels, which serve for labour, and sometimes for food, did not exist till the bethencourts made the conquest of the canaries. in the sixteenth century, asses were so abundant in the island of forteventura, that they became wild and were hunted. several thousands were killed to save the harvest. the horses of forteventura are of singular beauty, and of the barbary race.--"noticias de la historia general de las islas canarias" por don jose de viera, tome page .) and a short time after we saw the small island of lobos in the channel which separates forteventura from lancerota. we spent part of the night on deck. the moon illumined the volcanic summits of lancerota, the flanks of which, covered with ashes, reflected a silver light. antares threw out its resplendent rays near the lunar disk, which was but a few degrees above the horizon. the night was beautifully serene and cool. though we were but a little distance from the african coast, and on the limit of the torrid zone, the centigrade thermometer rose no higher than degrees. the phosphorescence of the ocean seemed to augment the mass of light diffused through the air. after midnight, great black clouds rising behind the volcano shrouded at intervals the moon and the beautiful constellation of the scorpion. we beheld lights carried to and fro on shore, which were probably those of fishermen preparing for their labours. we had been occasionally employed, during our passage, in reading the old voyages of the spaniards, and these moving lights recalled to our fancy those which pedro gutierrez, page of queen isabella, saw in the isle of guanahani, on the memorable night of the discovery of the new world. on the th, in the morning, the horizon was foggy, and the sky slightly covered with vapour. the outlines of the mountains of lancerota appeared stronger: the humidity, increasing the transparency of the air, seemed at the same time to have brought the objects nearer our view. this phenomenon is well known to all who have made hygrometrical observations in places whence the chain of the higher alps or of the andes is seen. we passed through the channel which divides the isle of alegranza from montana clara, taking soundings the whole way; and we examined the archipelago of small islands situated northward of lancerota. in the midst of this archipelago, which is seldom visited by vessels bound for teneriffe, we were singularly struck with the configuration of the coasts. we thought ourselves transported to the euganean mountains in the vicentin, or the banks of the rhine near bonn. the form of organized beings varies according to the climate, and it is that extreme variety which renders the study of the geography of plants and animals so attractive; but rocks, more ancient perhaps than the causes which have produced the difference of the climate on the globe, are the same in both hemispheres. the porphyries containing vitreous feldspar and hornblende, the phonolite, the greenstone, the amygdaloids, and the basalt, have forms almost as invariable as simple crystallized substances. in the canary islands, and in the mountains of auvergne, in the mittelgebirge in bohemia, in mexico, and on the banks of the ganges, the formation of trap is indicated by a symmetrical disposition of the mountains, by truncated cones, sometimes insulated, sometimes grouped, and by elevated plains, both extremities of which are crowned by a conical rising. the whole western part of lancerota, of which we had a near view, bears the appearance of a country recently convulsed by volcanic eruptions. everything is black, parched, and stripped of vegetable mould. we distinguished, with our glasses, stratified basalt in thin and steeply-sloping strata. several hills resembled the monte novo, near naples, or those hillocks of scoria and ashes which the opening earth threw up in a single night at the foot of the volcano of jorullo, in mexico. in fact, the abbe viera relates, that in , more than half the island changed its appearance. the great volcano, which we have just mentioned, and which the inhabitants call the volcano of temanfaya, spread desolation over a most fertile and highly cultivated region: nine villages were entirely destroyed by the lavas. this catastrophe had been preceded by a tremendous earthquake, and for several years shocks equally violent were felt. this last phenomenon is so much the more singular, as it seldom happens after an eruption, when the elastic vapours have found vent by the crater, after the ejection of the melted matter. the summit of the great volcano is a rounded hill, but not entirely conic. from the angles of altitude which i took at different distances, its absolute elevation did not appear to exceed three hundred toises. the neighbouring hills, and those of alegranza and isla clara, were scarcely above one hundred or one hundred and twenty toises. we may be surprised at the small elevation of these summits, which, viewed from the sea, wear so majestic a form; but nothing is more uncertain than our judgment on the greatness of angles, which are subtended by objects close to the horizon. from illusions of this sort it arose, that before the measures of messrs. de churruca and galleano, at cape pilar, navigators considered the mountains of the straits of magellan, and those of terra del fuego, to be extremely elevated. the island of lancerota bore formerly the name of titeroigotra. on the arrival of the spaniards, its inhabitants were distinguished from the other canarians by marks of greater civilization. their houses were built with freestone, while the guanches of teneriffe dwelt in caverns. at lancerota, a very singular custom prevailed at that time, of which we find no example except among the people of thibet. a woman had several husbands, who alternately enjoyed the prerogatives due to the head of a family. a husband was considered as such only during a lunar revolution, and whilst his rights were exercised by others, he remained classed among the household domestics. in the fifteenth century the island of lancerota contained two small distinct states, divided by a wall; a kind of monument which outlives national enmities, and which we find in scotland, in china, and peru. we were forced by the winds to pass between the islands of alegranza and montana clara, and as none on board the sloop had sailed through this passage, we were obliged to be continually sounding. we found from twenty-five to thirty-two fathoms. the lead brought up an organic substance of so singular a structure that we were for a long time doubtful whether it was a zoophyte or a kind of seaweed. the stem, of a brownish colour and three inches long, has circular leaves with lobes, and indented at the edges. the colour of these leaves is a pale green, and they are membranous and streaked like those of the adiantums and gingko biloba. their surface is covered with stiff whitish hairs; before their opening they are concave, and enveloped one in the other. we observed no mark of spontaneous motion, no sign of irritability, not even on the application of galvanic electricity. the stem is not woody, but almost of a horny substance, like the stem of the gorgons. azote and phosphorus having been abundantly found in several cryptogamous plants, an appeal to chemistry would be useless to determine whether this organized substance belonged to the animal or vegetable kingdom. its great analogy to several sea-plants, with adiantum leaves, especially the genus caulerpa of m. lamoureux, of which the fucus proliter of forskael is one of the numerous species, engaged us to rank it provisionally among the sea-wracks, and give it the name of fucus vitifolius. the bristles which cover this plant are found in several other fuci.* (* fucus lycopodioides, and f. hirsutus.) the leaf, examined with a microscope at the instant we drew it up from the water, did not present, it is true, those conglobate glands, or those opaque points, which the parts of fructification in the genera of ulva and fucus contain; but how often do we find seaweeds in such a state that we cannot yet distinguish any trace of seeds in their transparent parenchyma. the vine-leaved fucus presents a physiological phenomenon of the greatest interest. fixed to a piece of madrepore, this seaweed vegetates at the bottom of the ocean, at the depth of feet, notwithstanding which we found its leaves as green as those of our grasses. according to the experiments of bouguer, light is weakened after a passage of feet in the ratio of to . . the seaweed of alegranza consequently presents a new example of plants which vegetate in great obscurity without becoming white. several germs, enveloped in the bulbs of the lily tribes, the embryo of the malvaceae, of the rhamnoides, of the pistacea, the viscum, and the citrus, the branches of some subterraneous plants; in short, vegetables transported into mines, where the ambient air contains hydrogen or a great quantity of azote, become green without light. from these facts we are inclined to admit that it is not exclusively by the influence of the solar rays that this carburet of hydrogen is formed in the organs of plants, the presence of which makes the parenchyma appear of a lighter or darker green, according as the carbon predominates in the mixture. mr. turner, who has so well made known the family of the seaweeds, as well as many other celebrated botanists, are of opinion that most of the fuci which we gather on the surface of the ocean, and which, from the rd to the th degree of latitude and nd of longitude, appear to the mariner like a vast inundated meadow, grow primitively at the bottom of the ocean, and float only in their ripened state, when torn up by the motion of the waves. if this opinion be well founded, we must agree that the family of seaweeds offers formidable difficulties to naturalists, who persist in thinking that absence of light always produces whiteness; for how can we admit that so many species of ulvaceae and dictyoteae, with stems and green leaves, which float on the ocean, have vegetated on rocks near the surface of the water? from some notions which the captain of the pizarro had collected in an old portuguese itinerary, he thought himself opposite to a small fort, situated north of teguisa, the capital of the island of lancerota. mistaking a rock of basalt for a castle, he saluted it by hoisting the spanish flag, and sent a boat with an officer to inquire of the commandant whether any english vessels were cruising in the roads. we were not a little surprised to learn that the land which we had considered as a prolongation of the coast of lancerota, was the small island of graciosa, and that for several leagues there was not an inhabited place. we took advantage of the boat to survey the land, which enclosed a large bay. the small part of the island of graciosa which we traversed, resembles those promontories of lava seen near naples, between portici and torre del greco. the rocks are naked, with no marks of vegetation, and scarcely any of vegetable soil. a few crustaceous lichen-like variolariae, leprariae, and urceorariae, were scattered about upon the basalts. the lavas which are not covered with volcanic ashes remain for ages without any appearance of vegetation. on the african soil excessive heat and lengthened drought retard the growth of cryptogamous plants. the basalts of graciosa are not in columns, but are divided into strata ten or fifteen inches thick. these strata are inclined at an angle of degrees to the north-west. the compact basalt alternates with the strata of porous basalt and marl. the rock does not contain hornblende, but great crystals of foliated olivine, which have a triple cleavage.* (* blaettriger olivin.) this substance is decomposed with great difficulty. m. hauy considers it a variety of the pyroxene. the porous basalt, which passes into mandelstein, has oblong cavities from two to eight lines in diameter, lined with chalcedony, enclosing fragments of compact basalt. i did not remark that these cavities had the same direction, or that the porous rock lay on compact strata, as happens in the currents of lava of etna and vesuvius. the marl,* (* mergel.) which alternates more than a hundred times with the basalts, is yellowish, friable by decomposition, very coherent in the inside, and often divided into irregular prisms, analogous to the basaltic prisms. the sun discolours their surface, as it whitens several schists, by reviving a hydro-carburetted principle, which appears to be combined with the earth. the marl of graciosa contains a great quantity of chalk, and strongly effervesces with nitric acid, even on points where it is found in contact with the basalt. this fact is the more remarkable, as this substance does not fill the fissures of the rock, but its strata are parallel to those of the basalt; whence we may conclude that both fossils are of the same formation, and have a common origin. the phenomenon of a basaltic rock containing masses of indurated marl split into small columns, is also found in the mittelgebirge, in bohemia. visiting those countries in , in company with mr. freiesleben, we even recognized in the marl of the stiefelberg the imprint of a plant nearly resembling the cerastium, or the alsine. are these strata, contained in the trappean mountains, owing to muddy irruptions, or must we consider them as sediments of water, which alternate with volcanic deposits? this last hypothesis seems so much the less admissible, since, from the researches of sir james hall on the influence of pressure in fusions, the existence of carbonic acid in substances contained in basalt presents nothing surprising. several lavas of vesuvius present similar phenomena. in lombardy, between vicenza and albano, where the calcareous stone of the jura contains great masses of basalt, i have seen the latter enter into effervescence with the acids wherever it touches the calcareous rock. we had not time to reach the summit of a hill very remarkable for having its base formed of banks of clay under strata of basalt, like a mountain in saxony, called the scheibenbergen hugel, which is become celebrated on account of the disputes of volcanean and neptunean geologists. these basalts were covered with a mammiform substance, which i vainly sought on the peak of teneriffe, and which is known by the names of volcanic glass, glass of muller, or hyalite: it is the transition from the opal to the chalcedony. we struck off with difficulty some fine specimens, leaving masses that were eight or ten inches square untouched. i never saw in europe such fine hyalites as i found in the island of graciosa, and on the rock of porphyry called el penol de los banos, on the bank of the lake of mexico. two kinds of sand cover the shore; one is black and basaltic, the other white and quartzose. in a place exposed to the rays of the sun, the first raised the thermometer to . degrees ( degrees r.) and the second to degrees ( degrees r.) the temperature of the air in the shade was . or . degrees higher than that of the air over the sea. the quartzose sand contains fragments of feldspar. it is thrown back by the water, and forms, in some sort, on the surface of the rocks, small islets on which seaweed vegetates. fragments of granite have been observed at teneriffe; the island of gomora, from the details furnished me by m. broussonnet, contains a nucleus of micaceous schist:--the quartz disseminated in the sand, which we found on the shore of graciosa, is a different substance from the lavas and the trappean porphyries so intimately connected with volcanic productions. from these facts it seems to be evident that in the canary islands, as well as on the andes of quito, in auvergne, in greece, and throughout the greater part of the globe, subterraneous fires have pierced through the rocks of primitive formation. in treating hereafter of the great number of warm springs which we have seen issuing from granite, gneiss, and micaceous schist, we shall have occasion to return to this subject, which is one of the most important of the physical history of the globe. we re-embarked at sunset, and hoisted sail, but the breeze was too feeble to permit us to continue our course to teneriffe. the sea was calm; a reddish vapour covered the horizon, and seemed to magnify every object. in this solitude, amidst so many uninhabited islets, we enjoyed for a long time the view of rugged and wild scenery. the black mountains of graciosa appeared like perpendicular walls five or six hundred feet high. their shadows, thrown over the surface of the ocean, gave a gloomy aspect to the scenery. rocks of basalt, emerging from the bosom of the waters, wore the resemblance of the ruins of some vast edifice, and carried our thoughts back to the remote period when submarine volcanoes gave birth to new islands, or rent continents asunder. every thing which surrounded us seemed to indicate destruction and sterility; but the back-ground of the picture, the coasts of lancerota presented a more smiling aspect. in a narrow pass between two hills, crowned with scattered tufts of trees, marks of cultivation were visible. the last rays of the sun gilded the corn ready for the sickle. even the desert is animated wherever we can discover a trace of the industry of man. we endeavoured to get out of this bay by the pass which separates alegranza from montana clara, and through which we had easily entered to land at the northern point of graciosa. the wind having fallen, the currents drove us very near a rock, on which the sea broke with violence, and which is noted in the old charts under the name of hell, or infierno. as we examined this rock at the distance of two cables' length, we found that it was a mass of lava three or four toises high, full of cavities, and covered with scoriae resembling coke. we may presume that this rock,* (* i must here observe, that this rock is noted on the celebrated venetian chart of andrea bianco, but that the name of infierno is given, as in the more ancient chart of picigano, made in , to teneriffe, without doubt because the guanches considered the peak as the entrance into hell. in the same latitudes an island made its appearance in .) which modern charts call the west rock (roca del oeste), was raised by volcanic fire; and it might heretofore have been much higher; for the new island of the azores, which rose from the sea at successive periods, in and , had reached feet when it totally disappeared in , to the depth of feet. this opinion on the origin of the basaltic mass of the infierno is confirmed by a phenomenon, which was observed about the middle of the last century in these same latitudes. at the time of the eruption of the volcano of temanfaya, two pyramidal hills of lithoid lava rose from the bottom of the ocean, and gradually united themselves with the island of lancerota. as we were prevented by the fall of the wind, and by the currents, from repassing the channel of alegranza, we resolved on tacking during the night between the island of clara and the west rock. this resolution had nearly proved fatal. a calm is very dangerous near this rock, towards which the current drives with considerable force. we began to feel the effects of this current at midnight. the proximity of the stony masses, which rise perpendicularly above the water, deprived us of the little wind which blew: the sloop no longer obeyed the helm, and we dreaded striking every instant. it is difficult to conceive how a mass of basalt, insulated in the vast expanse of the ocean, can cause so considerable a motion of the waters. these phenomena, worthy the attention of naturalists, are well known to mariners; they are extremely to be dreaded in the pacific ocean, particularly in the small archipelago of the islands of galapagos. the difference of temperature which exists between the fluid and the mass of rocks does not explain the direction which these currents take; and how can we admit that the water is engulfed at the base of these rocks, (which often are not of volcanic origin) and that this continual engulfing determines the particles of water to fill up the vacuum that takes place. the wind having freshened a little towards the morning on the th, we succeeded in passing the channel. we drew very near the infierno the second time, and remarked the large crevices, through which the gaseous fluids probably issued, when this basaltic mass was raised. we lost sight of the small islands of alegranza, montana clara, and graciosa, which appear never to have been inhabited by the guanches. they are now visited only for the purpose of gathering archil, which production is, however, less sought after, since so many other lichens of the north of europe have been found to yield materials proper for dyeing. montana clara is noted for its beautiful canary-birds. the note of these birds varies with their flocks, like that of our chaffinches, which often differs in two neighbouring districts. montana clara yields pasture for goats, a fact which proves that the interior of this islet is less arid than its coasts. the name of alegranza is synonymous with the joyous, (la joyeuse,) which denomination it received from the first conquerors of the canary islands, the two norman barons, jean de bethencourt and gadifer de salle. this was the first point on which they landed. after remaining several days at graciosa, a small part of which we examined, they conceived the project of taking possession of the neighbouring island of lancerota, where they were welcomed by guadarfia, sovereign of the guanches, with the same hospitality that cortez found in the palace of montezuma. the shepherd king, who had no other riches than his goats, became the victim of base treachery, like the sultan of mexico. we sailed along the coasts of lancerota, of the island of lobos, and of forteventura. the second of these islands seems to have anciently formed part of the two others. this geological hypothesis was started in the seventeenth century by the franciscan, juan galindo. that writer supposed that king juba had named six canary islands only, because, in his time, three among them were contiguous. without admitting the probability of this hypothesis, some learned geographers have imagined they recognized, in the two islands nivaria and ombrios, the canaria and capraria of the ancients. the haziness of the horizon prevented us, during the whole of our passage from lancerota to teneriffe, from discovering the summit of the peak of teyde. if the height of this volcano is toises, as the last trigonometrical measure of borda indicates, its summit ought to be visible at a distance of leagues, supposing the eye on a level with the ocean, and a refraction equal to . of distance. it has been doubted whether the peak has ever been seen from the channel which separates lancerota from forteventura, and which is distant from the volcano, according to the chart of varela, degrees minutes, or nearly leagues. this phenomenon appears nevertheless to have been verified by several officers of the spanish navy. i had in my hand, on board the pizarro, a journal, in which it was noted, that the peak of teneriffe had been seen at miles distance, near the southern cape of lancerota, called pichiguera. its summit was discovered under an angle considerable enough to lead the observer, don manual baruti, to conclude that the volcano might have been visible at nine miles farther. it was in september, towards evening, and in very damp weather. reckoning fifteen feet for the elevation of the eye, i find, that to render an account of this phenomenon, we must suppose a refraction equal to . of the arch, which is not very extraordinary for the temperate zone. according to the observations of general roy, the refractions vary in england from one-twentieth to one-third; and if it be true that they reach these extreme limits on the coast of africa, (which i much doubt,) the peak, in certain circumstances, may be seen on the deck of a vessel as far off as leagues. navigators who have much frequented these latitudes, and who can reflect on the physical causes of the phenomena, are surprised that the peaks of teyde and of the azores* (* the height of this peak of the azores, according to fleurieu, is toises; to ferrer, toises; and to tofino, toises: but these measures are only approximative estimates. the captain of the pizarro, don manuel cagigal, proved to me, by his journal, that he observed the peak of the azores at the distance of leagues, when he was sure of his latitude within two minutes. the volcano was seen at degrees south-east, so that the error in longitude must have an almost imperceptible influence in the estimation of the distance. nevertheless, the angle which the peak of the azores subtended was so great, that the captain of the pizarro was of opinion this volcano must be visible at more than or leagues. the distance of leagues supposes an elevation of toises.) are sometimes visible at a very great distance, though at other times they are not seen when the distance is much less, and the sky appears serene and the horizon free from fogs. these circumstances are the more worthy of attention because vessels returning to europe, sometimes wait impatiently for a sight of these mountains, to rectify their longitude; and think themselves much farther off than they really are, when in fine weather these peaks are not perceptible at distances where the angles subtended must be very considerable. the constitution of the atmosphere has a great influence on the visibility of distant objects. it may be admitted, that in general the peak of teneriffe is seldom seen at a great distance, in the warm and dry months of july and august; and that, on the contrary, it is seen at very extraordinary distances in the months of january and february, when the sky is slightly clouded, and immediately after a heavy rain, or a few hours before it falls. it appears that the transparency of the air is prodigiously increased, as we have already observed, when a certain quantity of water is uniformly diffused through the atmosphere. independent of these observations, it is not astonishing, that the peak of teyde should be seldomer visible at a very remote distance, than the summits of the andes, to which, during so long a time, my observations were directed. this peak, inferior in height to those parts of the chain of mount atlas at the foot of which is the city of morocco, is not, like those points, covered with perpetual snows. the piton, or sugar-loaf, which terminates the peak, no doubt reflects a great quantity of light, owing to the whitish colour of the pumice-stone thrown up by the crater; but the height of that little truncated cone does not form a twenty-second part of the total elevation. the flanks of the volcano are covered either with blocks of black and scorified lava, or with a luxuriant vegetation, the masses of which reflect the less light, as the leaves of the trees are separated from each other by shadows of more considerable extent than that of the part enlightened. hence it results that, setting aside the piton, the peak of teyde belongs to that class of mountains, which, according to the expression of bouger, are seen at considerable distances only in a negative manner, because they intercept the light which is transmitted to us from the extreme limits of the atmosphere; and we perceive their existence only on account of the difference of intensity subsisting between the aerial light which surrounds them, and that which is reflected by the particles of air placed between the mountains and the eye of the observer. as we withdraw from the isle of teneriffe, the piton or sugar-loaf is seen for a considerable space of time in a positive manner, because it reflects a whitish light, and clearly detaches itself from the sky. but as this cone is only toises high, by in breadth at its summit, it has recently been a question whether, from the diminutiveness of its mass, it can be visible at distances which exceed leagues; and whether it be not probable, that navigators distinguish the peaks as a small cloud above the horizon, only when the base of the piton begins to be visible on it. if we admit, that the mean breadth of the sugar-loaf is toises, we find that the little cone, at leagues distance, still subtends, in the horizontal direction, an angle of more than three minutes. this angle is considerable enough to render an object visible; and if the height of the piton greatly exceeded its base, the angle in the horizontal direction might be still smaller, and the object still continue to make an impression on our visual organs; for micrometrical observations have proved that the limit of vision is but a minute only, when the dimensions of the objects are the same in every direction. we distinguish at a distance, by the eye only, trunks of trees insulated in a vast plain, though the subtended angle be under twenty-five seconds. as the visibility of an object detaching itself in a brown colour, depends on the quantities of light which the eye meets on two lines, one of which ends at the mountain, and the other extends to the surface of the aerial ocean, it follows that the farther we remove from the object, the smaller the difference becomes between the light of the surrounding atmosphere, and that of the strata of air before the mountain. for this reason, when less elevated summits begin to appear above the horizon, they present themselves at first under a darker hue than those we discern at very great distances. in the same manner, the visibility of mountains seen only in a negative manner, does not depend solely on the state of the lower regions of the air, to which our meteorological observations are limited, but also on the transparency and physical constitution of the air in the most elevated parts; for the image detaches itself better in proportion as the aerial light, which comes from the limits of the atmosphere, has been originally more intense, or has undergone less loss in its passage. this consideration explains to a certain point, why, under a perfectly serene sky, the state of the thermometer and the hygrometer being precisely the same in the air nearest the earth, the peak is sometimes visible, and at other times invisible, to navigators at equal distances. it is even probable, that the chance of perceiving this volcano would not be greater, if the ashy cone, at the summit of which is the mouth of the crater, were equal, as in vesuvius, to a quarter of the total height. these ashes, being pumice-stone crumbled into dust, do not reflect as much light as the snow of the andes; and they cause the mountain, seen from afar, to detach itself not in a bright, but in a dark hue. the ashes also contribute, if we may use the expression, to equalize the portions of aerial light, the variable difference of which renders the object more or less distinctly visible. calcareous mountains, devoid of vegetable earth, summits covered with granitic sand, the high savannahs of the cordilleras,* (* los pajonales, from paja, straw. this is the name given to the region of the gramina, which encircles the zone of the perpetual snows.) which are of a golden yellow, are undoubtedly distinguished at small distances better than objects which are seen in a negative manner; but the theory indicates a certain limit, beyond which these last detach themselves more distinctly from the azure vault of the sky. the colossal summits of quito and peru, towering above the limit of the perpetual snows, concentre all the peculiarities which must render them visible at very small angles. the circular summit of the peak of teneriffe is only a hundred toises in diameter. according to the measures i made at riobamba, in , the dome of the chimborazo, toises below its summit, consequently in a point which is toises higher than the peak, is still toises ( metres) in breadth. the zone of perpetual snows also forms a fourth of the height of the mountain; and the base of this zone, seen on the coast of the pacific, fills an extent of toises ( metres). but though chimborazo is two-thirds higher than the peak, we do not see it, on account of the curve of the globe, at more than miles and a third farther distant. the radiant brilliancy of its snows, when, at the port of guayaquil, at the close of the rainy season, chimborazo is discerned on the horizon, may lead us to suppose, that it must be seen at a very great distance in the south sea. pilots highly worthy of credit have assured me, that they have seen it from the rock of muerto, to the south west of the isle of puna, at a distance of leagues. whenever it has been seen at a greater distance, the observers, uncertain of their longitude, have not been in a situation to furnish precise data. aerial light, projected on mountains, increases the visibility of those which are seen positively; its power diminishes, on the contrary, the visibility of objects which, like the peak of teneriffe and that of the azores, detach themselves in a brown tint. bouguer, relying on theoretical considerations, was of opinion that, according to the constitution of our atmosphere, mountains seen negatively cannot be perceived at distances exceeding leagues. it is important here to observe, that these calculations are contrary to experience. the peak of teneriffe has been often seen at the distance of , , and even at leagues. moreover, in the vicinity of the sandwich islands, the summit of mowna-roa, at a season when it was without snows, has been seen on the skirt of the horizon, at the distance of leagues. this is the most striking example we have hitherto known of the visibility of a mountain; and it is the more remarkable, that an object seen negatively furnishes this example. the volcanoes of teneriffe, and of the azores, the sierra nevada of santa martha, the peak of orizaba, the silla of caracas, mowna-roa, and mount st. elias, insulated in the vast extent of the seas, or placed on the coasts of continents, serve as sea-marks to direct the pilot, when he has no means of determining the position of the vessel by the observation of the stars; everything which has a relation to the visibility of these natural seamarks, is interesting to the safety of navigation. chapter . . stay at tenerife. journey from santa cruz to orotava. excursion to the summit of the peak of teyde. from the time of our departure from graciosa, the horizon continued so hazy, that, notwithstanding the considerable height of the mountains of canary,* (* isla de la gran canaria.) we did not discover that island till the evening of the th of june. it is the granary of the archipelago of the fortunate islands; and, what is very remarkable in a region situated beyond the limits of the tropics, we were assured, that in some districts, there are two wheat harvests in the year; one in february, and the other in june. canary has never been visited by a learned mineralogist; yet this island is so much the more worthy of observation, as the physiognomy of its mountains, disposed in parallel chains, appeared to me to differ entirely from that of the summits of lancerota and teneriffe. nothing is more interesting to the geologist, than to observe the relations, on the same point of the globe, between volcanic countries, and those which are primitive or secondary. when the canary islands shall have been examined, in all the parts which compose the system of these mountains, we shall find that we have been too precipitate in considering the whole group as raised by the action of submarine fires. on the morning of the th, we discovered the point of naga, but the peak of teneriffe was still invisible: the land, obscured by a thick mist, presented forms that were vague and confused. as we approached the road of santa cruz we observed that the mist, driven by the winds, drew nearer to us. the sea was strongly agitated, as it most commonly is in those latitudes. we anchored after several soundings, for the mist was so thick, that we could scarcely distinguish objects at a few cables' distance; but at the moment we began to salute the place, the fog was instantly dispelled. the peak of teyde appeared in a break above the clouds, and the first rays of the sun, which had not yet risen on us, illumined the summit of the volcano. we hastened to the prow of the vessel to behold the magnificent spectacle, and at the same instant we saw four english vessels lying to, and very near our stern. we had passed without being perceived, and the same mist which had concealed the peak from our view, had saved us from the risk of being carried back to europe. the pizarro stood in as close as possible to the fort, to be under its protection. it was on this shore, that, in the landing attempted by the english two years before our arrival, in july , admiral nelson had his arm carried off by a cannon-ball. the situation of the town of santa cruz is very similar to that of la guayra, the most frequented port of the province of caraccas. the heat is excessive in both places, and from the same causes; but the aspect of santa cruz is more gloomy. on a narrow and sandy beach, houses of dazzling whiteness, with flat roofs, and windows without glass, are built close against a wall of black perpendicular rock, devoid of vegetation. a fine mole, built of freestone, and the public walk planted with poplars, are the only objects which break the sameness of the landscape. the view of the peak, as it presents itself above santa cruz, is much less picturesque than that we enjoy from the port of orotava. there, a highly cultured and smiling plain presents a pleasing contrast to the wild aspect of the volcano. from the groups of palm trees and bananas which line the coast, to the region of the arbutus, the laurel, and the pine, the volcanic rock is crowned with luxuriant vegetation. we easily conceive how the inhabitants, even of the beautiful climates of greece and italy, might fancy they recognised one of the fortunate isles in the western part of teneriffe. the eastern side, that of santa cruz, on the contrary, is every where stamped with sterility. the summit of the peak is not more arid than the promontory of basaltic lava, which stretches towards the point of naga, and on which succulent plants, springing up in the clefts of the rocks, scarcely indicate a preparation of soil. at the port of orotava, the top of the piton subtends an angle in height of more than eleven degrees and a half; while at the mole of santa cruz* (* the oblique distances from the top of the volcano to orotava and to santa cruz are nearly toises and , toises.) the angle scarcely exceeds degrees minutes. notwithstanding this difference, and though in the latter place the volcano rises above the horizon scarcely as much as vesuvius seen from the mole of naples, the aspect of the peak is still very majestic, when those who anchor in the road discern it for the first time. the piton alone was visible to us; its cone projected itself on a sky of the purest blue, whilst dark thick clouds enveloped the rest of the mountain to the height of toises. the pumice-stone, illumined by the first rays of the sun, reflected a reddish light, like that which tinges the summits of the higher alps. this light by degrees becomes dazzlingly white; and, deceived like most travellers, we thought that the peak was still covered with snow, and that we should with difficulty reach the edge of the crater. we have remarked, in the cordillera of the andes, that the conical mountains, such as cotopaxi and tungurahua, are oftener seen free from clouds, than those of which the tops are broken into bristly points, like antisana and pichincha; but the peak of teneriffe, notwithstanding its pyramidical form, is a great part of the year enveloped in vapours, and is sometimes, during several weeks, invisible from the road of santa cruz. its position to the west of an immense continent, and its insulated situation in the midst of the sea, are no doubt the causes of this phenomenon. navigators are well aware that even the smallest islets, and those which are without mountains, collect and harbour the clouds. the decrement of heat is also different above the plains of africa, and above the surface of the atlantic; and the strata of air, brought by the trade winds, cool in proportion as they advance towards the west. if the air has been extremely dry above the burning sands of the desert, it is very quickly saturated when it enters into contact with the surface of the sea, or with the air that lies on that surface. it is easy to conceive, therefore, why vapours become visible in the atmospherical strata, which, at a distance from the continent, have no longer the same temperature as when they began to be saturated with water. the considerable mass of a mountain, rising in the midst of the atlantic, is also an obstacle to the clouds, which are driven out to sea by the winds. on entering the streets of santa cruz, we felt a suffocating heat, though the thermometer was not above twenty-five degrees. those who have for a long time inhaled the air of the sea suffer every time they land; not because this air contains more oxygen than the air on shore, as has been erroneously supposed, but because it is less charged with those gaseous combinations, which the animal and vegetable substances, and the mud resulting from their decomposition, pour into the atmosphere. miasms that escape chemical analysis have a powerful effect on our organs, especially when they have not for a long while been exposed to the same kind of irritation. santa cruz, the anaza of the guanches, is a neat town, with a population of souls. i was not struck with the vast number of monks and secular ecclesiastics, which travellers have thought themselves bound to find in every country under the spanish government; nor shall i stop to enter into the description of the churches; the library of the dominicans, which contains scarcely a few hundred volumes; the mole, where the inhabitants assemble to inhale the freshness of the evening breeze; or the famed monument of carrara marble, thirty feet high, dedicated to our lady of candelaria, in memory of the miraculous appearance of the virgin, in , at chimisay, near guimar. the port of santa cruz may be considered as a great caravanserai, on the road to america and the indies. every traveller who writes the narrative of his adventures, begins by a description of madeira and teneriffe; and if in the natural history of these islands there yet remains an immense field untrodden, we must admit that the topography of the little towns of funchal, santa cruz, laguna, and orotava, leaves scarcely anything untold. the recommendation of the court of madrid procured for us, in the canaries, as in all the other spanish possessions, the most satisfactory reception. the captain-general gave us immediate permission to examine the island. colonel armiaga, who commanded a regiment of infantry, received us into his house with kind hospitality. we could not cease admiring the banana, the papaw tree, the poinciana pulcherrima, and other plants, which we had hitherto seen only in hot-houses, cultivated in his garden in the open air. the climate of the canaries however is not warm enough to ripen the real platano arton, with triangular fruit from seven to eight inches long, and which, requiring a temperature of centesimal degrees, does not flourish even in the valley of caracas. the bananas of teneriffe are those named by the spanish planters camburis or guineos, and dominicos. the camburi, which suffers least from cold, is cultivated with success even at malaga, where the temperature is only degrees; but the fruit we see occasionally at cadiz comes from the canary islands by vessels which make the passage in three or four days. in general, the musa, known by every people under the torrid zone, though hitherto never found in a wild state, has as great a variety of fruit as our apple and pear trees. these varieties, which are confounded by the greater part of botanists, though they require very different climates, have become permanent by long cultivation. we went to herborize in the evening in the direction of the fort of passo alto, along the basaltic rocks that close the promontory of naga. we were very little satisfied with our harvest, for the drought and dust had almost destroyed vegetation. the cacalia kleinia, the euphorbia canariensis, and several other succulent plants, which draw their nourishment from the air rather than the soil on which they grow, reminded us by their appearance, that this group of islands belongs to africa, and even to the most arid part of that continent. though the captain of the pizarro had orders to stop long enough at teneriffe to give us time to scale the summit of the peak, if the snows did not prevent our ascent, we received notice, on account of the blockade of the english ships, not to expect a longer delay than four or five days. we consequently hastened our departure for the port of orotava, which is situated on the western declivity of the volcano, where we were sure of finding guides. i could find no one at santa cruz who had mounted the peak, and i was not surprised at this. the most curious objects become less interesting, in proportion as they are near to us; and i have known inhabitants of schaffhausen, in switzerland, who had never seen the fall of the rhine but at a distance. on the th of june, before sunrise, we began our excursion by ascending to the villa de laguna, estimated to be at the elevation of toises above the port of santa cruz. we could not verify this estimate of the height, the surf not having permitted us to return on board during the night, to take our barometers and dipping-needle. as we foresaw that our expedition to the peak would be very precipitate, we consoled ourselves with the reflection that it was well not to expose instruments which were to serve us in countries less known by europeans. the road by which we ascended to laguna is on the right of a torrent, or baranco, which in the rainy season forms fine cascades; it is narrow and tortuous. near the town we met some white camels, which seemed to be very slightly laden. the chief employment of these animals is to transport merchandise from the custom-house to the warehouses of the merchants. they are generally laden with two chests of havannah sugar, which together weigh pounds; but this load may be augmented to thirteen hundred-weight, or arrobas of castile. camels are not numerous at teneriffe, whilst they exist by thousands in the two islands of lancerota and forteventura; the climate and vegetation of these islands, which are situated nearer africa, are more analogous to those of that continent. it is very extraordinary, that this useful animal, which breeds in south america, should be seldom propagated at teneriffe. in the fertile district of adexe only, where the plantations of the sugar-cane are most considerable, camels have sometimes been known to breed. these beasts of burden, as well as horses, were brought into the canary islands in the fifteenth century by the norman conquerors. the guanches were previously unacquainted with them; and this fact seems to be very well accounted for by the difficulty of transporting an animal of such bulk in frail canoes, without the necessity of considering the guanches as a remnant of the people of atlantis, or a different race from that of the western africans. the hill, on which the town of san christobal de la laguna is built, belongs to the system of basaltic mountains, which, independent of the system of less ancient volcanic rocks, form a broad girdle around the peak of teneriffe. the basalt on which we walked was darkish brown, compact, half-decomposed, and when breathed on, emitted a clayey smell. we discovered amphibole, olivine,* (* peridot granuliforme. hauy.) and translucid pyroxenes, * (* augite.--werner.) with a perfectly lamellar fracture, of a pale olive green, and often crystallized in prisms of six planes. the first of these substances is extremely rare at teneriffe; and i never found it in the lavas of vesuvius; but those of etna contain it in abundance. notwithstanding the great number of blocks, which we stopped to break, to the great regret of our guides, we could discover neither nepheline, leucite,* (* amphigene.--hauy.) nor feldspar. this last, which is so common in the basaltic lavas of the island of ischia, does not begin to appear at teneriffe, till we approach the volcano. the rock of laguna is not columnar, but is divided into ledges, of small thickness, and inclined to the east at an angle of or degrees. it has nowhere the appearance of a current of lava flowing from the sides of the peak. if the present volcano has given birth to these basalts, we must suppose, that, like the substances which compose the somma, at the back of vesuvius, they are the effect of a submarine effusion, in which the liquid mass has formed strata. a few arborescent euphorbias, the cacalia kleinia, and indian figs (cactus), which have become wild in the canary islands, as well as in the south of europe and the whole continent of africa, are the only plants we see on these arid rocks. the feet of our mules were slipping every moment on beds of stone, which were very steep. we nevertheless recognized the remains of an ancient pavement. in these colonies we discover at every step some traces of that activity which characterized the spanish nation in the th century. as we approached laguna, we felt the temperature of the atmosphere gradually become lower. this sensation was so much the more agreeable, as we found the air of santa cruz very oppressive. as our organs are more affected by disagreeable impressions, the change of temperature becomes still more sensible when we return from laguna to the port: we seem then to be drawing near the mouth of a furnace. the same impression is felt, when, on the coast of caracas, we descend from the mountain of avila to the port of la guayra. according to the law of the decrement of heat, three hundred and fifty toises in height produce in this latitude only three or four degrees difference in temperature. the heat which overpowers the traveller on his entrance into santa cruz, or la guayra, must consequently be attributed to the reverberation from the rocks, against which these towns are built. the perpetual coolness which prevails at laguna causes it to be considered in the canaries a delightful abode. situated in a small plain, surrounded by gardens, protected by a hill which is crowned by a wood of laurels, myrtle, and arbutus, the capital of teneriffe is very beautifully placed. we should be mistaken if, relying on the account of some travellers, we believed it seated on the border of a lake. the rain sometimes forms a sheet of water of considerable extent; and the geologist, who beholds in everything the past rather than the present state of nature, can have no doubt but that the whole plain is a great basin dried up. laguna has fallen from its opulence, since the lateral eruptions of the volcano have destroyed the port of garachico, and since santa cruz has become the central point of the commerce of the island. it contains only inhabitants, of whom nearly are monks, distributed in six convents. the town is surrounded with a great number of windmills, which indicate the cultivation of wheat in these high countries. i shall observe on this occasion, that different kinds of grain were known to the guanches. they called wheat at teneriffe tano, at lancerota triffa; barley, in the grand canary, bore the name of aramotanoque, and at lancerota it was called tamosen. the flour of roasted barley (gofio) and goat's-milk constituted the principal food of the people, on the origin of which so many systematic fables have been current. these aliments sufficiently prove that the race of the guanches belonged to the nations of the old continent, perhaps to those of caucasus, and not like the rest of the atlantides,* to the inhabitants of the new world (* without entering here into any discussion respecting the existence of the atlantis, i may cite the opinion of diodorus siculus, according to whom the atlantides were ignorant of the use of corn, because they were separated from the rest of mankind before these gramina were cultivated.); these, before the arrival of the europeans, were unacquainted with corn, milk, and cheese. a great number of chapels, which the spaniards call ermitas, encircle the town of laguna. shaded by trees of perpetual verdure, and erected on small eminences, these chapels add to the picturesque effect of the landscape. the interior of the town is not equal to its external appearance. the houses are solidly built, but very antique, and the streets seem deserted. a botanist ought not to complain of the antiquity of the edifices. the roofs and walls are covered with canary house-leek and those elegant trichomanes, mentioned by every traveller. these plants are nourished by the abundant mists. mr. anderson, the naturalist in the third voyage of captain cook, advises physicians to send their patients to teneriffe, on account of the mildness of the temperature and the equal climate of the canaries. the ground on these islands rises in an amphitheatre, and presents simultaneously, as in peru and mexico, the temperature of every climate, from the heat of africa to the cold of the higher alps. santa cruz, the port of orotava, the town of the same name, and that of laguna, are four places, the mean temperatures of which form a descending series. in the south of europe the change of the seasons is too sensibly felt to present the same advantages. teneriffe, on the contrary, situated as it were on the threshold of the tropics, though but a few days' sail from spain, shares in the charms which nature has lavished on the equinoctial regions. vegetation here displays some of her fairest and most majestic forms in the banana and the palm-tree. he who is alive to the charms of nature finds in this delicious island remedies still more potent than the climate. no abode appeared to me more fitted to dissipate melancholy, and restore peace to the perturbed mind, than that of teneriffe or madeira. these advantages are the effect not of the beauty of the site and the purity of the air alone: the moral feeling is no longer harrowed up by the sight of slavery, the presence of which is so revolting in the west indies, and in every other place to which european colonists have conveyed what they call their civilization and their industry. in winter the climate of laguna is extremely foggy, and the inhabitants often complain of the cold. a fall of snow, however, has never been seen; a fact which may seem to indicate that the mean temperature of this town must be above . degrees ( degrees r.), that is to say, higher than that of naples. i do not lay this down as an unexceptional conclusion, for in winter the refrigeration of the clouds does not depend so much on the mean temperature of the whole year, as on the instantaneous diminution of heat to which a district is exposed by its local situation. the mean temperature of the capital of mexico, for instance, is only . degrees ( . degrees r.), nevertheless, in the space of a hundred years snow has fallen only once, while in the south of europe and in africa it snows in places where the mean temperature is above degrees. the vicinity of the sea renders the climate of laguna more mild in winter than might be expected, arising from its elevation above the level of the ocean. i was astonished to learn that m. broussonnet had planted in the midst of this town, in the garden of the marquis de nava, the bread-fruit tree (artocarpus incisa), and cinnamon-tree (laurus cinnamomum). these valuable productions of the south sea and the east indies are naturalized there as well as at orotava. does not this fact prove that the bread-fruit might flourish in calabria, sicily, and granada? the culture of the coffee-tree has not equally succeeded at laguna, though its fruit ripens at teguesta, as well as between the port of orotava and the village of st. juan de la rambla. it is probable that some local circumstances, perhaps the nature of the soil and the winds that prevail in the flowering season, are the cause of this phenomenon. in other regions, in the neighbourhood of naples, for instance, the coffee-tree thrives abundantly, though the mean temperature scarcely rises above centigrade degrees. no person has ascertained in the island of teneriffe, the lowest height at which snow falls every year. this fact, though easy of verification by barometrical measurements, has hitherto been generally neglected under every zone. it is nevertheless highly interesting both to agriculture in the colonies and meteorology, and fully as important as the measure of the limit of the perpetual snows. my observations furnished me with the data, set down in the following table:-- column : north latitude. column : lowest height in toises at which snow falls. column : lowest height in metres at which snow falls. column : inferior limit in toises of the perpetual snows. column : inferior limit in metres of the perpetual snows. column : difference in toises of columns and . column : difference in metres of columns and . column : mean temperature degrees centigrade. column : mean temperature degrees reaum. : : : : : : : : . . : : : : : : : . : . . : : : : : : : : . . this table presents only the ordinary state of nature, that is to say, the phenomena as they are annually observed. exceptions founded on particular local circumstances, exist. thus it sometimes snows, though seldom, at naples, at lisbon, and even at malaga, consequently as low as the th degree of latitude: and, as we have just observed, snow has been seen to fall at mexico, the elevation of which is toises above the level of the ocean. this phenomenon, which had not been seen for several centuries, took place on the day that the jesuits were expelled, and was attributed by the people to that act of severity. a more striking exception was found in the climate of valladolid, the capital of the province of mechoacan. according to my measures, the height of this town, situate in latitude degrees minutes, is only a thousand toises: and yet, a few years before our arrival in new spain, the streets were covered with snow for some hours. snow had been seen to fall also at teneriffe, in a place lying above esperanza de la laguna, very near the town of that name, in the gardens of which the artocarpus flourishes. this extraordinary fact was confirmed to m. broussonnet by very aged persons. the erica arborea, the myrica faya, and the arbutus callicarpa,* (* this fine arbutus, imported by m. broussonnet, is very different from the arbutus laurifolia, with which it has been confounded, but which belongs to north america.) did not suffer from the snow; but it destroyed all the vines in the open air. this observation is interesting to vegetable physiology. in hot countries, the plants are so vigorous, that cold is less injurious to them, provided it be of short duration. i have seen the banana cultivated in the island of cuba, in places where the thermometer descends to seven centesimal degrees, and sometimes very near freezing point. in italy and spain the orange and date-trees do not perish, though the cold during the night may be two degrees below freezing point. in general it is remarked by cultivators, that the trees which grow in a fertile soil are less delicate, and consequently less affected by great changes in the temperature, than those which grow in land that affords but little nutriment.* (* the mulberries, cultivated in the thin and sandy soils of countries bordering on the baltic sea, are examples of this feebleness of organization. the late frosts do more injury to them, than to the mulberries of piedmont. in italy a cold of degrees below freezing point does not destroy robust orange trees. according to m. galesio, these trees, less tender than the lemon and bergamot orange trees, freeze only at ten centesimal degrees below freezing point.) in order to pass from the town of laguna to the port of orotava and the western coast of teneriffe, we cross at first a hilly region covered with black and argillaceous earth, in which are found some small crystals of pyroxene. the waters most probably detach these crystals from the neighbouring rocks, as at frascati, near rome. unfortunately, strata of ferruginous earth conceal the soil from the researches of the geologist. it is only in some ravines, that we find columnar basalts, somewhat curved, and above them very recent breccia, resembling volcanic tufa. the breccia contain fragments of the same basalts which they cover; and it is asserted that marine petrifactions are observed in them. the same phenomenon occurs in the vicentin, near montechio maggiore. the valley of tacoronte is the entrance into that charming country, of which travellers of every nation have spoken with rapturous enthusiasm. under the torrid zone i found sites where nature is more majestic, and richer in the display of organic forms; but after having traversed the banks of the orinoco, the cordilleras of peru, and the most beautiful valleys of mexico, i own that i have never beheld a prospect more varied, more attractive, more harmonious in the distribution of the masses of verdure and of rocks, than the western coast of teneriffe. the sea-coast is lined with date and cocoa trees. groups of the musa, as the country rises, form a pleasing contrast with the dragon-tree, the trunks of which have been justly compared to the tortuous form of the serpent. the declivities are covered with vines, which throw their branches over towering poles. orange trees loaded with flowers, myrtles, and cypress trees encircle the chapels reared to devotion on the isolated hills. the divisions of landed property are marked by hedges formed of the agave and the cactus. an innumerable quantity of cryptogamous plants, among which ferns are the most predominant, cover the walls, and are moistened by small springs of limpid water. in winter, when the volcano is buried under ice and snow, this district enjoys perpetual spring. in summer, as the day declines, the breezes from the sea diffuse a delicious freshness. the population of this coast is very considerable; and it appears to be still greater than it is, because the houses and gardens are distant from each other, which adds to the picturesque beauty of the scene. unhappily the real welfare of the inhabitants does not correspond with the exertions of their industry, or with the advantages which nature has lavished on this spot. the farmers are not land-owners; the fruits of their labour belong to the nobles; and those feudal institutions, which, for so long a time, spread misery throughout europe, still press heavily on the people of the canary islands. from tegueste and tacoronte to the village of st. juan de la rambla (which is celebrated for its excellent malmsey wine), the rising hills are cultivated like a garden. i might compare them to the environs of capua and valentia, if the western part of teneriffe was not infinitely more beautiful on account of the proximity of the peak, which presents on every side a new point of view. the aspect of this mountain is interesting not merely from its gigantic mass; it excites the mind, by carrying it back to the mysterious source of its volcanic agency. for thousands of years, no flames or light have been perceived on the summit of the piton, nevertheless enormous lateral eruptions, the last of which took place in , are proofs of the activity of a fire still far from being extinguished. there is also something that leaves a melancholy impression on beholding a crater in the centre of a fertile and well cultivated country. the history of the globe informs us, that volcanoes destroy what they have been a long series of ages in creating. islands, which the action of submarine fires has raised above the waters, are by degrees clothed in rich and smiling verdure; but these new lands are often laid waste by the renewed action of the same power which caused them to emerge from the bottom of the ocean. islets, which are now but heaps of scoriae and volcanic ashes, were once perhaps as fertile as the hills of tacoronte and sauzal. happy the country, where man has no distrust of the soil on which he lives! pursuing our course to the port of orotava, we passed the smiling hamlets of matanza and victoria. these names are mingled together in all the spanish colonies, and they form an unpleasing contrast with the peaceful and tranquil feelings which those countries inspire. matanza signifies slaughter, or carnage; and the word alone recalls the price at which victory has been purchased. in the new world it generally indicates the defeat of the natives: at teneriffe, the village of matanza was built in a place* (* the ancient acantejo.) where the spaniards were conquered by those same guanches who soon after were sold as slaves in the markets of europe. before we reached orotava, we visited a botanic garden at a little distance from the port. we there found m. le gros, the french vice-consul, who had often scaled the summit of the peak, and who served us as an excellent guide. he was accompanying captain baudin in a voyage to the west indies, when a dreadful tempest, of which m. le dru has given an account in the narrative of his voyage to porto rico, forced the vessel to put into teneriffe. there m. le gros was led by the beauty of the spot to settle. it was he who augmented scientific knowledge by the first accurate ideas of the great lateral eruption of the peak, which has been very improperly called the explosion of the volcano of chahorra. this eruption took place on the th of june, . the establishment of a botanical garden at teneriffe is a very happy idea, on account of the influence it is likely to have on the progress of botany, and on the introduction of useful plants into europe. for the first conception of it we are indebted to the marquis de nava. he undertook, at an enormous expense, to level the hill of durasno, which rises as an amphitheatre, and which was begun to be planted in . the marquis thought that the canary islands, from the mildness of their climate and geographical position, were the most suitable place for naturalising the productions of the east and west indies, and for inuring the plants gradually to the colder temperature of the south of europe. the plants of asia, africa, and south america, may easily be brought to orotava; and in order to introduce the bark-tree* into sicily, portugal, or grenada, it should be first planted at durasno, or at laguna, and the shoots of this tree may afterwards be transported into europe from the canaries. (* i speak of the species of bark-tree (cinchona), which at peru, and in the kingdom of new granada, flourish on the back of the cordilleras, at the height of between and toises, in places where the thermometer is between nine and ten degrees during the day, and from three to four during the night. the orange bark-tree (cinchona lancifolia) is much less delicate than the red bark-tree (c. oblongifolia).) in happier times, when maritime wars shall no longer interrupt communication, the garden of teneriffe may become extremely useful with respect to the great number of plants which are sent from the indies to europe; for ere they reach our coasts, they often perish, owing to the length of the passage, during which they inhale an air impregnated with salt water. these plants would meet at orotava with the care and climate necessary for their preservation. at durasno, the protea, the psidium, the jambos, the chirimoya of peru,* (* annona cherimolia. lamarck.) the sensitive plant, and the heliconia, grow in the open air. we gathered the ripened seeds of several beautiful species of glycine from new holland, which the governor of cumana, mr. emparan, had successfully cultivated, and which grow wild on the coasts of south america. we arrived very late at the port of orotava,* (* puerto de la cruz. the only fine port of the canary islands is that of st. sebastian, in the isle of gomara.) if we may give the name of port to a road in which vessels are obliged to put to sea whenever the winds blow violently from the north-west. it is impossible to speak of orotava without recalling to the remembrance of the friends of science the name of don bernardo cologan, whose house at all times was open to travellers of every nation. we could have wished to have sojourned for some time in don bernardo's house, and to have visited with him the charming scenery of st. juan de la rambla and of rialexo de abaxo.* (* this last-named village stands at the foot of the lofty mountain of tygayga.) but on a voyage such as we had undertaken, the present is but little enjoyed. continually haunted by the fear of not executing the designs of the morrow, we live in perpetual uneasiness. persons who are passionately fond of nature and the arts feel the same sensations, when they travel through switzerland and italy. enabled to see but a small portion of the objects which allure them, they are disturbed in their enjoyments by the restraints they impose on themselves at every step. on the morning of the st of june, we were on our way to the summit of the volcano. m. le gros, whose attentions were unwearied, m. lalande, secretary to the french consulate at santa cruz, and the english gardener at durasno, joined us on this excursion. the day was not very fine, and the summit of the peak, which is generally visible at orotava from sunrise till ten o'clock, was covered with thick clouds. we were agreeably surprised by the contrast between the vegetation of this part of teneriffe, and that of the environs of santa cruz. under the influence of a cool and humid climate, the ground was covered with beautiful verdure; while on the road from santa cruz to laguna the plants exhibited nothing but capsules emptied of their seeds. near the port of santa cruz, the strength of the vegetation is an obstacle to geological research. we passed along the base of two small hills, which rise in the form of bells. observations made at vesuvius and in auvergne lead us to think that these hills owe their origin to lateral eruptions of the great volcano. the hill called montanita de la villa seems indeed to have emitted lavas; and according to the tradition of the guanches, an eruption took place in . colonel franqui assured borda, that the place is still to be seen whence the melted matter issued; and that the ashes which covered the ground adjacent, were not yet fertilized. whenever the rock appeared, we discovered basaltic amygdaloid* (* basaltartiger mandelstein. werner.) covered with hardened clay,* (* bimstein-conglomerat. w.) which contains rapilli, or fragments of pumice-stone. this last formation resembles the tufas of pausilippo, and the strata of puzzolana, which i found in the valley of quito, at the foot of the volcano of pichincha. the amygdaloid has very long pores, like the superior strata of the lavas of vesuvius, arising probably from the action of an elastic fluid forcing its way through the matter in fusion. notwithstanding these analogies, i must here repeat, that in all the low region of the peak of teneriffe, on the side of orotava, i have met with no flow of lava, nor any current, the limits of which are strongly marked. torrents and inundations change the surface of the globe, and when a great number of currents of lava meet and spread over a plain, as i have seen at vesuvius, in the atrio dei cavalli, they seem to be confounded together, and wear the appearance of real strata. the villa de orotava has a pleasant aspect at a distance, from the great abundance of water which runs through the principal streets. the spring of agua mansa, collected in two large reservoirs, turns several mills, and is afterward discharged among the vineyards of the adjacent hills. the climate is still more refreshing at the villa than at the port of la cruz, from the influence of the breeze, which blows strong after ten in the morning. the water, which has been dissolved in the air at a higher temperature, frequently precipitates itself; and renders the climate very foggy. the villa is nearly toises ( metres) above the level of the sea, consequently toises lower than the site on which laguna is built: it is observed also, that the same kind of plants flower a month later in this latter place. orotava, the ancient taoro of the guanches, is situated on a very steep declivity. the streets seem deserted; the houses are solidly built, and of a gloomy appearance. we passed along a lofty aqueduct, lined with a great number of fine ferns; and visited several gardens, in which the fruit trees of the north of europe are mingled with orange trees, pomegranate, and date trees. we were assured, that these last were as little productive here as on the coast of cumana. although we had been made acquainted, from the narratives of many travellers, with the dragon-tree of the garden of m. franqui, we were not the less struck with its enormous magnitude. we were told, that the trunk of this tree, which is mentioned in several very ancient documents as marking the boundaries of a field, was as gigantic in the fifteenth century as it is at the present time. its height appeared to us to be about or feet; its circumference near the roots is feet. we could not measure higher, but sir george staunton found that, feet from the ground, the diameter of the trunk is still english feet; which corresponds perfectly with the statement of borda, who found its mean circumference feet inches, french measure. the trunk is divided into a great number of branches, which rise in the form of a candelabrum, and are terminated by tufts of leaves, like the yucca which adorns the valley of mexico. this division gives it a very different appearance from that of the palm-tree. among organic creations, this tree is undoubtedly, together with the adansonia or baobab of senegal, one of the oldest inhabitants of our globe. the baobabs are of still greater dimensions than the dragon-tree of orotava. there are some which near the root measure feet in diameter, though their total height is only from to feet. but we should observe, that the adansonia, like the ochroma, and all the plants of the family of bombax, grow much more rapidly* than the dracaena, the vegetation of which is very slow. (* it is the same with the plane-tree (platanus occidentalis) which m. michaux measured at marietta, on the banks of the ohio, and which, at twenty feet from the ground, was . feet in diameter. --"voyage a l'ouest des monts alleghany" page . the yew, chestnut, oak, plane-tree, deciduous cypress, bombax, mimosa, caesalpina, hymenaea, and dracaena, appear to me to be the plants which, in different climates, present specimens of the most extraordinary growth. an oak, discovered together with some gallic helmets in , in the turf pits of the department of the somme, near the village of yseux, seven leagues from abbeville, was about the same size as the dragon-tree of orotava. according to a memoir by m. traullee, the trunk of this oak was feet in diameter.) that in m. franqui's garden still bears every year both flowers and fruit. its aspect forcibly exemplifies "that eternal youth of nature," which is an inexhaustible source of motion and of life. the dracaena, which is seen only in cultivated spots in the canary islands, at madeira, and porto santo, presents a curious phenomenon with respect to the migration of plants. it has never been found in a wild state on the continent of africa. the east indies is its real country. how has this tree been transplanted to teneriffe, where it is by no means common? does its existence prove, that, at some very distant period, the guanches had connexions with other nations originally from asia?* (* the form of the dragon-tree is exhibited in several species of the genus dracaena, at the cape of good hope, in china, and in new zealand. but in new zealand it is superseded by the form of the yucca; for the dracaena borealis of aiton is a convallaria, of which it has all the appearance. the astringent juice, known in commerce by the name of dragon's blood, is, according to the inquiries we made on the spot, the produce of several american plants, which do not belong to the same genus and of which some are lianas. at laguna, toothpicks steeped in the juice of the dragon-tree are made in the nunneries, and are much extolled as highly useful for keeping the gums in a healthy state.) on leaving orotava, a narrow and stony pathway led us through a beautiful forest of chestnut trees (el monte de castanos), to a site covered with brambles, some species of laurels, and arborescent heaths. the trunks of the latter grow to an extraordinary size; and the flowers with which they are loaded form an agreeable contrast, during a great part of the year, to the hypericum canariense, which is very abundant at this height. we stopped to take in our provision of water under a solitary fir-tree. this station is known in the country by the name of pino del dornajito. its height, according to the barometrical measurement of m. de borda, is toises; and it commands a magnificent prospect of the sea, and the whole of the northern part of the island. near pino del dornajito, a little on the right of the pathway, is a copious spring of water, into which we plunged the thermometer, which fell to . degrees. at a hundred toises distance from this spring is another equally limpid. if we admit that these waters indicate nearly the mean heat of the place whence they issue, we may fix the absolute elevation of the station at toises, supposing the mean temperature of the coast to be degrees, and allowing one degree for the decrement of caloric corresponding under this zone to toises. we should not be surprised if this spring remained a little below the heat of the air, since it probably takes its source in some more elevated part of the peak, and possibly communicates with the small subterranean glaciers of which we shall speak hereafter. the accordance just observed between the barometrical and thermometrical measures is so much more striking, because in mountainous countries, with steep declivities, the springs generally indicate too great a decrement of caloric, for they unite small currents of water, which filtrate at different heights, and their temperature is consequently the mean between the temperature of these currents. the spring of dornajito has considerable reputation in the country; and at the time i was there, it was the only one known on the road which leads to the summit of the volcano. the formation of springs demands a certain regularity in the direction and inclination of the strata. on a volcanic soil, porous and splintered rocks absorb the rain waters, and convey them to considerable depths. hence arises that aridity observed in the greater part of the canary islands, notwithstanding the considerable height of their mountains, and the mass of clouds which navigators behold incessantly overhanging this archipelago. from pino del dornajito to the crater of the volcano we continued to ascend without crossing a single valley; for the small ravines (barancos) do not merit this name. to the eye of the geologist the whole island of teneriffe is but one mountain, the almost elliptical base of which is prolonged to the north-east, and in which may be distinguished several systems of volcanic rocks formed at different epochs. the chahorra, or montana colorada, and the urca, considered in the country as insulated volcanoes, are only little hills abutting on the peak, and masking its pyramidal form. the great volcano, the lateral eruptions of which have given birth to vast promontories, is not however precisely in the centre of the island, and this peculiarity of structure appears the less surprising, if we recollect that, as the learned mineralogist m. cordier has observed, it is not perhaps the small crater of the piton which has been the principal agent in the changes undergone by the island of teneriffe. above the region of arborescent heaths, called monte verde, is the region of ferns. nowhere, in the temperate zone, have i seen such an abundance of the pteris, blechnum, and asplenium; yet none of these plants have the stateliness of the arborescent ferns which, at the height of five or six hundred toises, form the principal ornament of equinoctial america. the root of the pteris aquilina serves the inhabitants of palma and gomera for food; they grind it to powder, and mix with it a quantity of barley-meal. this composition, when boiled, is called gofio; the use of so homely an aliment is a proof of the extreme poverty of the lower order of people in the canary islands. monte verde is intersected by several small and very arid ravines (canadas), and the region of ferns is succeeded by a wood of juniper trees and firs, which has suffered greatly from the violence of hurricanes. in this place, mentioned by some travellers under the name of caravela,* (* "philosophical transactions" volume page . carabela is the name of a vessel with lateen sails. the pines of the peak formerly were used as masts of vessels.) mr. eden states that in the year he saw little flames, which, according to the doctrine of the naturalists of his time, he attributes to sulphurous exhalations igniting spontaneously. we continued to ascend, till we came to the rock of la gayta and to portillo: traversing this narrow pass between two basaltic hills, we entered the great plain of spartium. at the time of the voyage of laperouse, m. manneron had taken the levels of the peak, from the port of orotava to this elevated plain, near toises above the level of the sea; but the want of water, and the misconduct of the guides, prevented him from taking the levels to the top of the volcano. the results of the operation, (which was two-thirds completed,) unfortunately were not sent to europe, and the work is still to be recommenced from the sea-coast. we spent two hours and a half in crossing the llano del retama, which appears like an immense sea of sand. notwithstanding the elevation of this site, the centigrade thermometer rose in the shade toward sunset, to . degrees, or . degrees higher than toward noon at monte verde. this augmentation of heat could be attributed only to the reverberation from the ground, and the extent of the plain. we suffered much from the suffocating dust of the pumice-stone, in which we were continually enveloped. in the midst of this plain are tufts of the retama, which is the spartium nubigenum of aiton. m. de martiniere, one of the botanists who perished in the expedition of laperouse, wished to introduce this beautiful shrub into languedoc, where firewood is very scarce. it grows to the height of nine feet, and is loaded with odoriferous flowers, with which the goat hunters, that we met in our road, had decorated their hats. the goats of the peak, which are of a deep brown colour, are reckoned delicious food; they browse on the spartium, and have run wild in the deserts from time immemorial. they have been transported to madeira, where they are preferred to the goats of europe. as far as the rock of gayta, or the entrance of the extensive llano del retama, the peak of teneriffe is covered with beautiful vegetation. there are no traces of recent devastation. we might have imagined ourselves scaling the side of some volcano, the fire of which had been extinguished as remotely as that of monte cavo, near rome; but scarcely had we reached the plain covered with pumice-stone, when the landscape changed its aspect, and at every step we met with large blocks of obsidian thrown out by the volcano. everything here speaks perfect solitude. a few goats and rabbits only bound across the plain. the barren region of the peak is nine square leagues; and as the lower regions viewed from this point retrograde in the distance, the island appears an immense heap of torrefied matter, hemmed round by a scanty border of vegetation. from the region of the spartium nubigenum we passed through narrow defiles, and small ravines hollowed at a very remote time by the torrents, first arriving at a more elevated plain (el monton de trigo), then at the place where we intended to pass the night. this station, which is more than toises above the coast, bears the name of the english halt (estancia de los ingleses* (* this denomination was in use as early as the beginning of the last century. mr. eden, who corrupts all spanish words, as do most travellers in our own times, calls it the stancha: it is the station des rochers of m. borda, as is proved by the barometrical heights there observed. these heights were in , according to m. cordier, inches . lines; and in , according to messrs. borda and varela, inches . lines; the barometer at orotava keeping within nearly a line at the same height.)), no doubt because most of the travellers, who formerly visited the peak, were englishmen. two inclined rocks form a kind of cavern, which affords a shelter from the winds. this point, which is higher than the summit of the canigou, can be reached on the backs of mules; and here has ended the expedition of numbers of travellers, who on leaving orotava hoped to have ascended to the brink of the crater. though in the midst of summer, and under an african sky, we suffered from cold during the night. the thermometer descended as low as to five degrees. our guides made a large fire with the dry branches of retama. having neither tents nor cloaks, we lay down on some masses of rock, and were singularly incommoded by the flame and smoke, which the wind drove towards us. we had attempted to form a kind of screen with cloths tied together, but our enclosure took fire, which we did not perceive till the greater part had been consumed by the flames. we had never passed a night on a point so elevated, and we then little imagined that we should, one day, on the ridge of the cordilleras, inhabit towns higher than the summit of the volcano we were to scale on the morrow. as the temperature diminished, the peak became covered with thick clouds. the approach of night interrupts the play of the ascending current, which, during the day, rises from the plains towards the high regions of the atmosphere; and the air, in cooling, loses its capacity of suspending water. a strong northerly wind chased the clouds; the moon at intervals, shooting through the vapours, exposed its disk on a firmament of the darkest blue; and the view of the volcano threw a majestic character over the nocturnal scenery. sometimes the peak was entirely hidden from our eyes by the fog, at other times it broke upon us in terrific proximity; and, like an enormous pyramid, threw its shadow over the clouds rolling beneath our feet. about three in the morning, by the sombrous light of a few fir torches, we started on our journey to the summit of the piton. we scaled the volcano on the north-east side, where the declivities are extremely steep; and after two hours' toil, we reached a small plain, which, on account of its elevated position, bears the name of alta vista. this is the station of the neveros, those natives, whose occupation it is to collect ice and snow, which they sell in the neighbouring towns. their mules, better practised in climbing mountains than those hired by travellers, reach alta vista, and the neveros are obliged to transport the snow to that place on their backs. above this point commences the malpays, a term by which is designated here, as well as in mexico, peru, and every other country subject to volcanoes, a ground destitute of vegetable mould, and covered with fragments of lava. we turned to the right to examine the cavern of ice, which is at the elevation of toises, consequently below the limit of the perpetual snows in this zone. probably the cold which prevails in this cavern, is owing to the same causes which perpetuate the ice in the crevices of mount jura and the apennines, and on which the opinions of naturalists are still much divided. this natural ice-house of the peak has, nevertheless, none of those perpendicular openings, which give emission to the warm air, while the cold air remains undisturbed at the bottom. it would seem that the ice is preserved in it on account of its mass, and because its melting is retarded by the cold, which is the consequence of quick evaporation. this small subterraneous glacier is situated in a region, the mean temperature of which is probably not under three degrees; and it is not, like the true glaciers of the alps, fed by the snow waters that flow from the summits of the mountains. during winter the cavern is filled with ice and snow; and as the rays of the sun do not penetrate beyond the mouth, the heats of summer are not sufficient to empty the reservoir. the existence of a natural ice-house depends, consequently, rather on the quantity of snow which enters it in winter, and the small influence of the warm winds in summer, than on the absolute elevation of the cavity, and the mean temperature of the layer of air in which it is situated. the air contained in the interior of a mountain is not easily displaced, as is exemplified by monte testaccio at rome, the temperature of which is so different from that of the surrounding atmosphere. on chimborazo enormous heaps of ice are found covered with sand, and, in the same manner as at the peak, far below the inferior limit of the perpetual snows. it was near the ice-cavern (cueva del hielo), that, in the voyage of laperouse, messrs. lamanon and monges made their experiments on the temperature of boiling water. these naturalists found it . degrees, the barometer at nineteen inches one line. in the kingdom of new grenada, at the chapel of guadaloupe, near santa-fe de bogota, i have seen water boil at . degrees, under a pressure of inches . lines, at tambores, in the province of popayan, senor caldas found the heat of boiling water . degrees, the barometer being at inches . lines. these results might lead us to suspect, that, in the experiment of m. lamanon, the water had not reached the maximum of its temperature. day was beginning to dawn when we left the ice-cavern. we observed, during the twilight, a phenomenon which is not unusual on high mountains, but which the position of the volcano we were scaling rendered very striking. a layer of white and fleecy clouds concealed from us the sight of the ocean, and the lower region of the island. this layer did not appear above toises high; the clouds were so uniformly spread, and kept so perfect a level, that they wore the appearance of a vast plain covered with snow. the colossal pyramid of the peak, the volcanic summits of lancerota, of forteventura, and the isle of palma, were like rocks amidst this vast sea of vapours, and their black tints were in fine contrast with the whiteness of the clouds. while we were climbing over the broken lavas of the malpays, we perceived a very curious optical phenomenon, which lasted eight minutes. we thought we saw on the east side small rockets thrown into the air. luminous points, about seven or eight degrees above the horizon, appeared first to move in a vertical direction; but their motion was gradually changed into a horizontal oscillation. our fellow-travellers, our guides even, were astonished at this phenomenon, without our having made any remark on it to them. we thought, at first sight, that these luminous points, which floated in the air, indicated some new eruption of the great volcano of lancerota; for we recollected that bouguer and la condamine, in scaling the volcano of pichincha, were witnesses of the eruption of cotopaxi. but the illusion soon ceased, and we found that the luminous points were the images of several stars magnified by the vapours. these images remained motionless at intervals, they then seemed to rise perpendicularly, descended sideways, and returned to the point whence they had departed. this motion lasted one or two seconds. though we had no exact means of measuring the extent of the lateral shifting, we did not the less distinctly observe the path of the luminous point. it did not appear double from an effect of mirage, and left no trace of light behind. bringing, with the telescope of a small sextant by troughton, the stars into contact with the lofty summit of a mountain in lancerota, i observed that the oscillation was constantly directed towards the same point, that is to say, towards that part of the horizon where the disk of the sun was to appear; and that, making allowance for the motion of the star in its declination, the image returned always to the same place. these appearances of lateral refraction ceased long before daylight rendered the stars quite invisible. i have faithfully related what we saw during the twilight, without undertaking to explain this extraordinary phenomenon, of which i published an account in baron zach's astronomical journal, twelve years ago. the motion of the vesicular vapours, caused by the rising of the sun; the mingling of several layers of air, the temperature and density of which were very different, no doubt contributed to produce an apparent movement of the stars in the horizontal direction. we see something similar in the strong undulations of the solar disk, when it cuts the horizon; but these undulations seldom exceed twenty seconds, while the lateral motion of the stars, observed at the peak, at more than toises, was easily distinguished by the naked eye, and seemed to exceed all that we have thought it possible to consider hitherto as the effect of the refraction of the light of the stars. on the top of the andes, at antisana, i observed the sun-rise, and passed the whole night at the height of toises, without noting any appearance resembling this phenomenon. i was anxious to make an exact observation of the instant of sun-rising at an elevation so considerable as that we had reached on the peak of teneriffe. no traveller, furnished with instruments, had as yet taken such an observation. i had a telescope and a chronometer, which i knew to be exceedingly correct. in the part where the sun was to appear the horizon was free from vapour. we perceived the upper limb at hours minutes seconds apparent time, and what is very remarkable, the first luminous point of the disk appeared immediately in contact with the limit of the horizon, consequently we saw the true horizon; that is to say, a part of the sea farther distant than leagues. it is proved by calculation that, under the same parallel in the plain, the rising would have begun at hours minute . seconds, or minutes . seconds later than at the height of the peak. the difference observed was minutes seconds, which arose no doubt from the uncertainty of the refraction for a zenith distance, of which observations are wanting. we were surprised at the extreme slowness with which the lower limb of the sun seemed to detach itself from the horizon. this limb was not visible till hours minutes seconds. the disc of the sun, much flattened, was well defined; during the ascent there was neither double image nor lengthening of the lower limb. the duration of the sun's rising being triple that which we might have expected in this latitude, we must suppose that a fog-bank, very uniformly extended, concealed the true horizon, and followed the sun in its ascent. notwithstanding the libration of the stars,* which we had observed towards the east, we could not attribute the slowness of the rising to an extraordinary refraction of the rays occasioned by the horizon of the sea; for it is precisely at the rising of the sun, as le gentil daily observed at pondicherry, and as i have several times remarked at cumana, that the horizon sinks, on account of the elevation of temperature in the stratum of the air which lies immediately over the surface of the ocean. (* a celebrated astronomer, baron zach, has compared this phenomenon of an apparent libration of the stars to that described in the georgics (lib. v. ). but this passage relates only to the falling stars, which the ancients, (like the mariners of modern times) considered as a prognostic of wind.) the road, which we were obliged to clear for ourselves across the malpays, was extremely fatiguing. the ascent is steep, and the blocks of lava rolled from beneath our feet. i can compare this part of the road only to the moraine of the alps or that mass of pebbly stones which we find at the lower extremity of the glaciers. at the peak the lava, broken into sharp pieces, leaves hollows, in which we risked falling up to our waists. unfortunately the listlessness of our guides contributed to increase the difficulty of this ascent. unlike the guides of the valley of chamouni, or the nimble-footed guanches, who could, it is asserted, seize the rabbit or wild goat in its course, our canarian guides were models of the phlegmatic. they had wished to persuade us on the preceding evening not to go beyond the station of the rocks. every ten minutes they sat down to rest themselves, and when unobserved they threw away the specimens of obsidian and pumice-stone, which we had carefully collected. we discovered at length that none of them had ever visited the summit of the volcano. after three hours' walking, we reached, at the extremity of the malpays, a small plain, called la rambleta, from the centre of which the piton, or sugar-loaf, takes its rise. on the side toward orotava the mountain resembles those pyramids with steps that are seen at fayoum and in mexico; for the elevated plains of retama and rambleta form two tiers, the first of which is four times higher than the second. if we suppose the total height of the peak to be toises, the rambleta is toises above the level of the sea. here are found those spiracles, which are called by the natives the nostrils of the peak (narices del pico). watery and heated vapours issue at intervals from several crevices in the ground, and the thermometer rose to . degrees. m. labillardiere had found the temperature of these vapours, eight years before us, . degrees; a difference which does not perhaps prove so much a diminution of activity in the volcano, as a local change in the heating of its internal surface. the vapours have no smell, and seem to be pure water. a short time before the great eruption of mount vesuvius, in , m. gay-lussac and myself had observed that water, under the form of vapour, in the interior of the crater, did not redden paper which had been dipped in syrup of violets. i cannot, however, admit the bold hypothesis, according to which the nostrils of the peak are to be considered as the vents of an immense apparatus of distillation, the lower part of which is situated below the level of the sea. since the time when volcanoes have been carefully studied, and the love of the marvellous has been less apparent in works on geology, well founded doubts have been raised respecting these direct and constant communications between the waters of the sea and the focus of the volcanic fire.* (* this question has been examined with much sagacity by m. brieslak, in his "introduzzione alla geologia," tome pages , , . cotopaxi and popocatepetl, which i saw ejecting smoke and ashes, in , are farther from both the pacific and the gulf of the antilles, than grenoble is from the mediterranean, and orleans from the atlantic. we must not consider the fact as merely accidental, that we have not yet discovered an active volcano more than leagues distant from the ocean; but i consider the hypothesis, that the waters of the sea are absorbed, distilled, and decomposed by volcanoes, as very doubtful.) we may find a very simple explanation of a phenomenon, that has in it nothing very surprising. the peak is covered with snow during part of the year; we ourselves found it still so in the plain of rambleta. messrs. o'donnel and armstrong discovered in a very abundant spring in the malpays, a hundred toises above the cavern of ice, which is perhaps fed partly by this snow. everything consequently leads us to presume that the peak of teneriffe, like the volcanoes of the andes, and those of the island of manilla, contains within itself great cavities, which are filled with atmospherical water, owing merely to filtration. the aqueous vapours exhaled by the narices and crevices of the crater, are only those same waters heated by the interior surfaces down which they flow. we had yet to scale the steepest part of the mountain, the piton, which forms the summit. the slope of this small cone, covered with volcanic ashes, and fragments of pumice-stone, is so steep, that it would have been almost impossible to reach the top, had we not ascended by an old current of lava, the debris of which have resisted the ravages of time. these debris form a wall of scorious rock, which stretches into the midst of the loose ashes. we ascended the piton by grasping these half-decomposed scoriae, which often broke in our hands. we employed nearly half an hour to scale a hill, the perpendicular height of which is scarcely ninety toises. vesuvius, three times lower than the peak of teneriffe, is terminated by a cone of ashes almost three times higher, but with a more accessible and easy slope. of all the volcanoes which i have visited, that of jorullo, in mexico, is the only one that is more difficult to climb than the peak, because the whole mountain is covered with loose ashes. when the sugar-loaf (el piton) is covered with snow, as it is in the beginning of winter, the steepness of its declivity may be very dangerous to the traveller. m. le gros showed us the place where captain baudin was nearly killed when he visited the peak of teneriffe. that officer had the courage to undertake, in company with the naturalists advenier, mauger, and riedle, an excursion to the top of the volcano about the end of december, . having reached half the height of the cone, he fell, and rolled down as far as the small plain of rambleta; happily a heap of lava, covered with snow, hindered him from rolling farther with accelerated velocity. i have been told, that in switzerland a traveller was suffocated by rolling down the declivity of the col de balme, over the compact turf of the alps. when we gained the summit of the piton, we were surprised to find scarcely room enough to seat ourselves conveniently. we were stopped by a small circular wall of porphyritic lava, with a base of pitchstone, which concealed from us the view of the crater.* (* called la caldera, or the caldron of the peak, a denomination which recalls to mind the oules of the pyrenees.) the west wind blew with such violence that we could scarcely stand. it was eight in the morning, and we suffered severely from the cold, though the thermometer kept a little above freezing point. for a long time we had been accustomed to a very high temperature, and the dry wind increased the feeling of cold, because it carried off every moment the small atmosphere of warm and humid air, which was formed around us from the effect of cutaneous perspiration. the brink of the crater of the peak bears no resemblance to those of most of the other volcanoes which i have visited: for instance, the craters of vesuvius, jorullo, and pichincha. in these the piton preserves its conic figure to the very summit: the whole of their declivity is inclined the same number of degrees, and uniformly covered with a layer of pumice-stone very minutely divided; when we reach the top of these volcanoes, nothing obstructs the view of the bottom of the crater. the peaks of teneriffe and cotopaxi, on the contrary, are of very different construction. at their summit a circular wall surrounds the crater; which wall, at a distance, has the appearance of a small cylinder placed on a truncated cone. on cotopaxi this peculiar construction is visible to the naked eye at more than toises distance; and no person has ever reached the crater of that volcano. on the peak of teneriffe, the wall, which surrounds the crater like a parapet, is so high, that it would be impossible to reach the caldera, if, on the eastern side, there was not a breach, which seems to have been the effect of a flowing of very old lava. we descended through this breach toward the bottom of the funnel, the figure of which is elliptic. its greater axis has a direction from north-west to south-east, nearly north degrees west. the greatest breadth of the mouth appeared to us to be feet, the smallest feet, which numbers agree very nearly with the measurement of mm. verguin, varela, and borda. it is easy to conceive, that the size of a crater does not depend solely on the height and mass of the mountain, of which it forms the principal air-vent. this opening is indeed seldom in direct ratio with the intensity of the volcanic fire, or with the activity of the volcano. at vesuvius, which is but a hill compared with the peak of teneriffe, the diameter of the crater is five times greater. when we reflect, that very lofty volcanoes throw out less matter from their summits than from lateral openings, we should be led to think, that the lower the volcanoes, their force and activity being the same, the more considerable ought to be their craters. in fact, there are immense volcanoes in the andes, which have but very small openings; and we might establish as a geological principle, that the most colossal mountains have craters of little extent at the summits, if the cordilleras did not present many instances to the contrary.* (* the great volcanoes of cotopaxi and rucupichincha have craters, the diameters of which, according to my measurements, exceed and toises.) i shall have occasion, in the progress of this work, to cite a number of facts, which will throw some light on what may be called the external structure of volcanoes. this structure is as varied as the volcanic phenomena themselves; and in order to raise ourselves to geological conceptions worthy of the greatness of nature, we must set aside the idea that all volcanoes are formed after the model of vesuvius, stromboli, and etna. the external edges of the caldera are almost perpendicular. their appearance is somewhat like the somma, seen from the atrio dei cavalli. we descended to the bottom of the crater on a train of broken lava, from the eastern breach of the enclosure. the heat was perceptible only in a few crevices, which gave vent to aqueous vapours with a peculiar buzzing noise. some of these funnels or crevices are on the outside of the enclosure, on the external brink of the parapet that surrounds the crater. we plunged the thermometer into them, and saw it rise rapidly to and degrees. it no doubt indicated a higher temperature, but we could not observe the instrument till we had drawn it up, lest we should burn our hands. m. cordier found several crevices, the heat of which was that of boiling water. it might be thought that these vapours, which are emitted in gusts, contain muriatic or sulphurous acid; but when condensed, they have no particular taste; and experiments, which have been made with re-agents, prove that the chimneys of the peak exhale only pure water. this phenomenon, analogous to that which i observed in the crater of jorullo, deserves the more attention, as muriatic acid abounds in the greater part of volcanoes, and as m. vauquelin has discovered it even in the porphyritic lavas of sarcouy in auvergne. i sketched on the spot a view of the interior edge of the crater, as it presented itself in the descent by the eastern break. nothing is more striking than the manner in which these strata of lava are piled on one another, exhibiting the sinuosities of the calcareous rock of the higher alps. these enormous ledges, sometimes horizontal, sometimes inclined and undulating, are indicative of the ancient fluidity of the whole mass, and of the combination of several deranging causes, which have determined the direction of each flow. the top of the circular wall exhibits those curious ramifications which we find in coke. the northern edge is most elevated. towards the south-west the enclosure is considerably sunk and an enormous mass of scorious lava seems glued to the extremity of the brink. on the west the rock is perforated; and a large opening gives a view of the horizon of the sea. the force of the elastic vapours perhaps formed this natural aperture, at the time of some inundation of lava thrown out from the crater. the inside of this funnel indicates a volcano, which for thousands of years has vomited no fire but from its sides. this conclusion is not founded on the absence of great openings, which might be expected in the bottom of the caldera. those whose experience is founded on personal observation, know that several volcanoes, in the intervals of an eruption, appear filled up, and almost extinguished; but that in these same mountains, the crater of the volcano exhibits layers of scoriae, rough, sonorous, and shining. we observe hillocks and intumescences caused by the action of the elastic vapours, cones of broken scoriae and ashes which cover the funnels. none of these phenomena characterise the crater of the peak of teneriffe; its bottom is not in the state which ensues at the close of an eruption. from the lapse of time, and the action of the vapours, the inside walls are detached, and have covered the basin with great blocks of lithoid lavas. the bottom of the caldera is reached without danger. in a volcano, the activity of which is principally directed towards the summit, such as vesuvius, the depth of the crater varies before and after each eruption; but at the peak of teneriffe the depth appears to have remained unchanged for a long time. eden, in , estimated it at feet; cordier, in , at feet. judging by mere inspection, i should have thought the funnel of still less depth. its present state is that of a solfatara; and it is rather an object of curious investigation, than of imposing aspect. the majesty of the site consists in its elevation above the level of the sea, in the profound solitude of these lofty regions, and in the immense space over which the eye ranges from the summit of the mountain. the wall of compact lava, forming the enclosure of the caldera, is snow-white at its surface. the same colour prevails in the inside of the solfatara of puzzuoli. when we break these lavas, which might be taken at some distance for calcareous stone, we find in them a blackish brown nucleus. porphyry, with basis of pitch-stone, is whitened externally by the slow action of the vapours of sulphurous acid gas. these vapours rise in abundance; and what is rather remarkable, through crevices which seem to have no communication with the apertures that emit aqueous vapours. we may be convinced of the presence of the sulphurous acid, by examining the fine crystals of sulphur, which are everywhere found in the crevices of the lava. this acid, combined with the water with which the soil is impregnated, is transformed into sulphuric acid by contact with the oxygen of the atmosphere. in general, the humidity in the crater of the peak is more to be feared than the heat; and they who seat themselves for a while on the ground find their clothes corroded. the porphyritic lavas are affected by the action of the sulphuric acid: the alumine, magnesia, soda, and metallic oxides gradually disappear; and often nothing remains but the silex, which unites in mammillary plates, like opal. these siliceous concretions,* (* opalartiger kieselsinter. the siliceous gurh of the volcanoes of the isle of france contains, according to klaproth, . silex, and . water; and thus comes near to opal, which karsten considers as a hydrated silex.) which m. cordier first made known, are similar to those found in the isle of ischia, in the extinguished volcanoes of santa fiora, and in the solfatara of puzzuoli. it is not easy to form an idea of the origin of these incrustations. the aqueous vapours, discharged through great spiracles, do not contain alkali in solution, like the waters of the geyser, in iceland. perhaps the soda contained in the lavas of the peak acts an important part in the formation of these deposits of silex. there may exist in the crater small crevices, the vapours of which are not of the same nature as those on which travellers, whose attention has been directed simultaneously to a great number of objects, have made experiments. seated on the northern brink of the crater, i dug a hole of some inches in depth; and the thermometer placed in this hole rose rapidly to degrees. hence we may conclude what must be the heat in this solfatara at the depth of thirty or forty fathoms. the sulphur reduced into vapour is condensed into fine crystals, which however are not equal in size to those m. dolomieu brought from sicily. they are semi-diaphanous octahedrons, very brilliant on the surface, and of a conchoidal fracture. these masses, which will one day perhaps be objects of commerce, are constantly bedewed with sulphurous acid. i had the imprudence to wrap up a few, in order to preserve them, but i soon discovered that the acid had consumed not only the paper which contained them, but a part also of my mineralogical journal. the heat of the vapours, which issue from the crevices of the caldera, is not sufficiently great to combine the sulphur while in a state of minute division, with the oxygen of the atmospheric air; and after the experiment i have just cited on the temperature of the soil, we may presume that the sulphurous acid is formed at a certain depth,* in cavities to which the external air has free access. (* an observer, in general very accurate, m. breislack, asserts that the muriatic acid always predominates in the vapours of vesuvius. this assertion is contrary to what m. gay-lussac and myself observed, before the great eruption of , and while the lava was issuing from the crater. the smell of the sulphurous acid, so easy to distinguish, was perceptible at a great distance; and when the volcano threw out scoriae, the smell was mingled with that of petroleum.) the vapours of heated water, which act on the fragments of lava scattered about on the caldera, reduce certain parts of it to a state of paste. on examining, after i had reached america, those earthy and friable masses, i found crystals of sulphate of alumine. mm. davy and gay-lussac have already made the ingenious remark, that two bodies highly inflammable, the metals of soda and potash, have probably an important part in the action of a volcano; now the potash necessary to the formation of alum is found not only in feldspar, mica, pumice-stone, and augite, but also in obsidian. this last substance is very common at teneriffe, where it forms the basis of the tephrinic lava. these analogies between the peak of teneriffe and the solfatara of puzzuoli, might no doubt be shown to be more numerous, if the former were more accessible, and had been frequently visited by naturalists. an expedition to the summit of the volcano of teneriffe is interesting, not solely on account of the great number of phenomena which are the objects of scientific research; it has still greater attractions from the picturesque beauties which it lays open to those who are feelingly alive to the majesty of nature. it is a difficult task to describe the sensations, which are the more forcible, inasmuch as they have something undefined, produced by the immensity of the space as well as by the vastness, the novelty, and the multitude of the objects, amidst which we find ourselves transported. when a traveller attempts to describe the loftiest summits of the globe, the cataracts of the great rivers, the tortuous valleys of the andes, he incurs the danger of fatiguing his readers by the monotonous expression of his admiration. it appears to me more conformable to the plan i have proposed to myself in this narrative, to indicate the peculiar character that distinguishes each zone: we exhibit with more clearness the physiognomy of the landscape, in proportion as we endeavour to sketch its individual features, to compare them with each other, and to discover by this kind of analysis the sources of the enjoyments, furnished by the great picture of nature. travellers have learned by experience, that views from the summits of very lofty mountains are neither so beautiful, picturesque, nor so varied, as those from heights which do not exceed that of vesuvius, righi, and the puy-de-dome. colossal mountains, such as chimborazo, antisana, or mount rosa, compose so large a mass, that the plains covered with rich vegetation are seen only in the immensity of distance, and a blue and vapoury tint is uniformly spread over the landscape. the peak of teneriffe, from its slender form and local position, unites the advantages of less lofty summits with those peculiar to very great heights. we not only discern from its top a vast expanse of sea, but we perceive also the forests of teneriffe, and the inhabited parts of the coasts, in a proximity calculated to produce the most beautiful contrasts of form and colour. we might say, that the volcano overwhelms with its mass the little island which serves as its base, and it shoots up from the bosom of the waters to a height three times loftier than the region where the clouds float in summer. if its crater, half extinguished for ages past, shot forth flakes of fire like that of stromboli in the aeolian islands, the peak of teneriffe, like a lighthouse, would serve to guide the mariner in a circuit of more than leagues. when we were seated on the external edge of the crater, we turned our eyes towards the north-west, where the coasts are studded with villages and hamlets. at our feet, masses of vapour, constantly drifted by the winds, afforded us the most variable spectacle. a uniform stratum of clouds, similar to that already described, and which separated us from the lower regions of the island, had been pierced in several places by the effect of the small currents of air, which the earth, heated by the sun, began to send towards us. the port of orotava, its vessels at anchor, the gardens and the vineyards encircling the town, shewed themselves through an opening which seemed to enlarge every instant. from the summit of these solitary regions our eyes wandered over an inhabited world; we enjoyed the striking contrast between the bare sides of the peak, its steep declivities covered with scoriae, its elevated plains destitute of vegetation, and the smiling aspect of the cultured country beneath. we beheld the plants divided by zones, as the temperature of the atmosphere diminished with the elevation of the site. below the piton, lichens begin to cover the scorious and lustrous lava: a violet,* (* viola cheiranthifolia.) akin to the viola decumbens, rises on the slope of the volcano at toises of height; it takes the lead not only of the other herbaceous plants, but even of the gramina, which, in the alps and on the ridge of the cordilleras, form close neighbourhood with the plants of the family of the cryptogamia. tufts of retama, loaded with flowers, adorn the valleys hollowed out by the torrents, and encumbered with the effects of the lateral eruptions. below the retama, lies the region of ferns, bordered by the tract of the arborescent heaths. forests of laurel, rhamnus, and arbutus, divide the ericas from the rising grounds planted with vines and fruit trees. a rich carpet of verdure extends from the plain of spartium, and the zone of the alpine plants even to the groups of the date tree and the musa, at the feet of which the ocean appears to roll. i here pass slightly over the principal features of this botanical chart, as i shall enter hereafter into some farther details respecting the geography of the plants of the island of teneriffe.* (* see below.) the seeming proximity, in which, from the summit of the peak, we behold the hamlets, the vineyards, and the gardens on the coast, is increased by the prodigious transparency of the atmosphere. notwithstanding the great distance, we could distinguish not only the houses, the sails of the vessels, and the trunks of the trees, but we could discern the vivid colouring of the vegetation of the plains. these phenomena are owing not only to the height of the site, but to the peculiar modifications of the air in warm climates. in every zone, an object placed on a level with the sea, and viewed in a horizontal direction, appears less luminous, than when seen from the top of a mountain, where vapours arrive after passing through strata of air of decreasing density. differences equally striking are produced by the influence of climate. the surface of a lake or large river is less resplendent, when we see it at an equal distance, from the top of the higher alps of switzerland, than when we view it from the summit of the cordilleras of peru or of mexico. in proportion as the air is pure and serene, the solution of the vapours becomes more complete, and the light loses less in its passage. when from the shores of the pacific we ascend the elevated plain of quito, or that of antisana, we are struck for some days by the nearness at which we imagine we see objects which are actually seven or eight leagues distant. the peak of teyde has not the advantage of being situated in the equinoctial region; but the dryness of the columns of air which rise perpetually above the neighbouring plains of africa, and which the eastern winds convey with rapidity, gives to the atmosphere of the canary islands a transparency which not only surpasses that of the air of naples and sicily, but perhaps exceeds the purity of the sky of quito and peru. this transparency may be regarded as one of the chief causes of the beauty of landscape scenery in the torrid zone; it heightens the splendour of the vegetable colouring, and contributes to the magical effect of its harmonies and contrasts. if the mass of light, which circulates about objects, fatigues the external senses during a part of the day, the inhabitant of the southern climates has his compensation in moral enjoyment. a lucid clearness in the conceptions, and a serenity of mind, correspond with the transparency of the surrounding atmosphere. we feel these impressions without going beyond the boundaries of europe. i appeal to travellers who have visited countries rendered famous by the great creations of the imagination and of art,--the favoured climes of italy and greece. we prolonged in vain our stay on the summit of the peak, awaiting the moment when we might enjoy the view of the whole of the archipelago of the fortunate islands:* we, however, descried palma, gomera, and the great canary, at our feet. (* of all the small islands of the canaries, the rock of the east is the only one which cannot be seen, even in fine weather, from the top of the peak. its distance is degrees minutes, while that of the salvage is only degrees minute. the island of madeira, distant degrees minutes, would be visible, if its mountains were more than toises high.) the mountains of lancerota, free from vapours at sunrise, were soon enveloped in thick clouds. supposing only an ordinary refraction, the eye takes in, in calm weather, from the summit of the volcano, a surface of the globe of square leagues, equal to a fourth of the superficies of spain. the question has often been agitated, whether it be possible to perceive the coast of africa from the top of this colossal pyramid; but the nearest parts of that coast are still farther from teneriffe than degrees minutes, or leagues. the visual ray of the horizon from the peak being degree minutes, cape bojador can be seen only on the supposition of its height being toises above the level of the ocean. we are ignorant of the height of the black mountains near cape bojador, as well as of that peak, called by navigators the penon grande, farther to the south of this promontory. if the summit of the volcano of teneriffe were more accessible, we should observe without doubt, in certain states of the wind, the effects of an extraordinary refraction. on perusing what spanish and portuguese authors relate respecting the existence of the fabulous isle of san borondon, or antilia, we find that it is particularly the humid wind from west-south-west, which produces in these latitudes the phenomena of the mirage. we shall not however admit with m. vieyra, "that the play of the terrestrial refractions may render visible to the inhabitants of the canaries the islands of cape verd, and even the apalachian mountains of america."* (* the american fruits, frequently thrown by the sea on the coasts of the islands of ferro and gomera, were formerly supposed to emanate from the plants of the island of san borondon. this island, said to be governed by an archbishop and six bishops, and which father feijoa believed to be the image of the island of ferro, reflected on a fog-bank, was ceded in the th century, by the king of portugal, to lewis perdigon, at the time the latter was preparing to take possession of it by conquest.) the cold we felt on the top of the peak, was very considerable for the season. the centigrade thermometer, at a distance from the ground, and from the apertures that emitted the hot vapours, fell in the shade to . degrees. the wind was west, and consequently opposite to that which brings to teneriffe, during a great part of the year, the warm air that floats above the burning desert of africa. as the temperature of the atmosphere, observed at the port of orotava by m. savagi, was . degrees, the decrement of caloric was one degree every toises. this result perfectly corresponds with those obtained by lamanon and saussure on the summits of the peak and etna, though in very different seasons. the tall slender form of these mountains facilitates the means of comparing the temperature of two strata of the atmosphere, which are nearly in the same perpendicular plane; and in this point of view the observations made in an excursion to the volcano of teneriffe resemble those of an ascent in a balloon. we must nevertheless remark, that the ocean, on account of its transparency and evaporation, reflects less caloric than the plains, into the upper regions of the air; and also that summits which are surrounded by the sea are colder in summer, than mountains which rise from a continent; but this circumstance has very little influence on the decrement of atmospherical heat; the temperature of the low regions being equally diminished by the proximity of the ocean. it is not the same with respect to the influence exercised by the direction of the wind, and the rapidity of the ascending current; the latter sometimes increases in an astonishing manner the temperature of the loftiest mountains. i have seen the thermometer rise, on the slope of the volcano of antisana, in the kingdom of quito, to degrees, when we were toises high. m. labillardiere has seen it, on the edge of the crater of the peak of teneriffe, at . degrees, though he had used every possible precaution to avoid the effect of accidental causes. on the summit of the peak, we beheld with admiration the azure colour of the sky. its intensity at the zenith appeared to correspond to degrees of the cyanometer. we know, by saussure's experiment, that this intensity increases with the rarity of the air, and that the same instrument marked at the same period degrees at the priory of chamouni, and degrees at the top of mont blanc. this last mountain is toises higher than the volcano of teneriffe; and if, notwithstanding this difference, the sky is observed there to be of a less deep blue, we must attribute this phenomenon to the dryness of the african air, and the proximity of the torrid zone. we collected on the brink of the crater, some air which we meant to analyse on our voyage to america. the phial remained so well corked, that on opening it ten days after, the water rushed in with impetuosity. several experiments, made by means of nitrous gas in the narrow tube of fontana's eudiometer, seemed to prove that the air of the crater contained . degrees less oxygen than the air of the sea; but i have little confidence in this result obtained by means which we now consider as very inexact. the crater of the peak has so little depth, and the air is renewed with so much facility, that it is scarcely probable the quantity of azote is greater there than on the coasts. we know also, from the experiments of mm. gay-lussac and theodore de saussure, that in the highest as well as in the lowest regions of the atmosphere, the air equally contains . of oxygen.* (* during the stay of m. gay-lussac and myself at the hospice of mont cenis, in march , we collected air in the midst of a cloud loaded with electricity. this air, analysed in volta's eudiometer, contained no hydrogen, and its purity did not differ . of oxygen from the air of paris, which we had carried with us in phials hermetically sealed.) we saw on the summit of the peak no trace of psora, lecidea, or other cryptogamous plants; no insect fluttered in the air. we found however a few hymenoptera adhering to masses of sulphur moistened with sulphurous acid, and lining the mouths of the funnels. these are bees, which appear to have been attracted by the flowers of the spartium nubigenum, and which oblique currents of air had carried up to these high regions, like the butterflies found by m. ramond at the top of mont perdu. the butterflies perished from cold, while the bees on the peak were scorched on imprudently approaching the crevices where they came in search of warmth. notwithstanding the heat we felt in our feet on the edge of the crater, the cone of ashes remains covered with snow during several months in winter. it is probable, that under the cap of snow considerable hollows are found, like those existing under the glaciers of switzerland, the temperature of which is constantly less elevated than that of the soil on which they repose. the cold and violent wind, which blew from the time of sunrise, induced us to seek shelter at the foot of the piton. our hands and faces were nearly frozen, while our boots were burnt by the soil on which we walked. we descended in the space of a few minutes the sugar-loaf which we had scaled with so much toil; and this rapidity was in part involuntary, for we often rolled down on the ashes. it was with regret that we quitted this solitude, this domain where nature reigns in all her majesty. we consoled ourselves with the hope of once again visiting the canary islands, but this, like many other plans we then formed, has never been executed. we traversed the malpays but slowly; for the foot finds no sure foundation on the loose blocks of lava. nearer the station of the rocks, the descent becomes extremely difficult; the compact short-swarded turf is so slippery, that we were obliged to incline our bodies continually backward, in order to avoid falling. in the sandy plain of retama, the thermometer rose to . degrees; and this heat seemed to us suffocating in comparison with the cold, which we had suffered from the air on the summit of the volcano. we were absolutely without water; our guides, not satisfied with drinking clandestinely the little supply of malmsey wine, for which we were indebted to don cologan's kindness, had broken our water jars. happily the bottle which contained the air of the crater escaped unhurt. we at length enjoyed the refreshing breeze in the beautiful region of the arborescent erica and fern; and we were enveloped in a thick bed of clouds stationary at six hundred toises above the plain. the clouds having dispersed, we remarked a phenomenon which afterwards became familiar to us on the declivities of the cordilleras. small currents of air chased trains of cloud with unequal velocity, and in opposite directions: they bore the appearance of streamlets of water in rapid motion and flowing in all directions, amidst a great mass of stagnant water. the causes of this partial motion of the clouds are probably very various; we may suppose them to arise from some impulsion at a great distance; from the slight inequalities of the soil, which reflects in a greater or less degree the radiant heat; from a difference of temperature kept up by some chemical action; or perhaps from a strong electric charge of the vesicular vapours. as we approached the town of orotava, we met great flocks of canaries.* (* fringilla canaria. la caille relates, in the narrative of his voyage to the cape, that on salvage island these canaries are so abundant, that you cannot walk there in a certain season without breaking their eggs.) these birds, well known in europe, were in general uniformly green. some, however, had a yellow tinge on their backs; their note was the same as that of the tame canary. it is nevertheless remarked, that those which have been taken in the island of the great canary, and in the islet of monte clara, near lancerota, have a louder and at the same time a more harmonious song. in every zone, among birds of the same species, each flock has its peculiar note. the yellow canaries are a variety, which has taken birth in europe; and those we saw in cages at orotava and santa cruz had been bought at cadiz, and in other ports of spain. but of all the birds of the canary islands, that which has the most heart-soothing song is unknown in europe. it is the capirote, which no effort has succeeded in taming, so sacred to his soul is liberty. i have stood listening in admiration of his soft and melodious warbling, in a garden at orotava; but i have never seen him sufficiently near to ascertain to what family he belongs. as to the parrots, which were supposed to have been seen at the period of captain cook's abode at teneriffe, they never existed but in the narratives of a few travellers, who have copied from each other. neither parrots nor monkeys inhabit the canary islands; and though in the new continent the former migrate as far as north carolina, i doubt whether in the old they have ever been met with beyond the th degree of north latitude. toward the close of day we reached the port of orotava, where we received the unexpected intelligence that the pizarro would not set sail till the th or th. if we could have calculated on this delay, we should either have lengthened our stay on the peak,* or have made an excursion to the volcano of chahorra. (* as a great number of travellers who land at santa cruz, do not undertake the excursion to the peak, because they are ignorant of the time it occupies, it may be useful to lay down the following data: in making use of mules as far as the estancia de los ingleses, it takes twenty-one hours from orotava to arrive at the summit of the peak, and return to the port; namely, from orotava to the pino del dornajito three hours; from the pino to the station of the rocks six hours; and from this station to the caldera three hours and a half. i reckon nine hours for the descent. in this calculation i count only the time employed in walking, without reckoning that which is necessary for examining the productions of the peak, or for taking rest. half a day is sufficient for going from santa cruz to orotava.) we passed the following day in visiting the environs of orotava, and enjoying the agreeable company we found at don cologan's. we perceived that teneriffe had attractions not only to those who devote themselves to the study of nature: we found at orotava several persons possessing a taste for literature and music, and who have transplanted into these distant climes the amenity of european society. in these respects the canary islands have no great resemblance to the other spanish colonies, excepting the havannah. we were present on the eve of st. john at a pastoral fete in the garden of mr. little. this gentleman, who rendered great service to the canarians during the last famine, has cultivated a hill covered with volcanic substances. he has formed in this delicious site an english garden, whence there is a magnificent view of the peak, of the villages along the coast, and the isle of palma, which is bounded by the vast expanse of the atlantic. i cannot compare this prospect with any, except the views of the bays of genoa and naples; but orotava is greatly superior to both in the magnitude of the masses and in the richness of vegetation. in the beginning of the evening the slope of the volcano exhibited on a sudden a most extraordinary spectacle. the shepherds, in conformity to a custom, no doubt introduced by the spaniards, though it dates from the highest antiquity, had lighted the fires of st. john. the scattered masses of fire and the columns of smoke driven by the wind, formed a fine contrast with the deep verdure of the forests which covered the sides of the peak. shouts of joy resounding from afar were the only sounds that broke the silence of nature in these solitary regions. don cologan's family has a country-house nearer the coast than that i have just mentioned. this house, called la paz, is connected with a circumstance that rendered it peculiarly interesting to us. m. de borda, whose death we deplored, was its inmate during his last visit to the canary islands. it was in a neighbouring plain that he measured the base, by which he determined the height of the peak. in this geometrical operation the great dracaena of orotava served as a mark. should any well-informed traveller at some future day undertake a new measurement of the volcano with more exactness, and by the help of astronomical repeating circles, he ought to measure the base, not near orotava, but near los silos, at a place called bante. according to m. broussonnet there is no plain near the peak of greater extent. in herborizing near la paz we found a great quantity of lichen roccella on the basaltic rocks bathed by the waters of the sea. the archil of the canaries is a very ancient branch of commerce; this lichen is however found in less abundance in the island of teneriffe than in the desert islands of salvage, la graciosa, and alegranza, or even in canary and hierro. we left the port of orotava on the th of june. to avoid disconnecting the narrative of the excursion to the top of the peak, i have said nothing of the geological observations i made on the structure of this colossal mountain, and on the nature of the volcanic rocks of which it is composed. before we quit the archipelago of the canaries, i shall linger for a moment, and bring into one point of view some facts relating to the physical aspect of those countries. mineralogists who think that the end of the geology of volcanoes is the classification of lavas, the examination of the crystals they contain, and their description according to their external characters, are generally very well satisfied when they come back from the mouth of a burning volcano. they return loaded with those numerous collections, which are the principal objects of their research. this is not the feeling of those who, without confounding descriptive mineralogy (oryctognosy) with geognosy, endeavour to raise themselves to ideas generally interesting, and seek, in the study of nature, for answers to the following questions:-- is the conical mountain of a volcano entirely formed of liquified matter heaped together by successive eruptions, or does it contain in its centre a nucleus of primitive rocks covered with lava, which are these same rocks altered by fire? what are the affinities which unite the productions of modern volcanoes with the basalts, the phonolites, and those porphyries with bases of feldspar, which are without quartz, and which cover the cordilleras of peru and mexico, as well as the small groups of the monts dores, of cantal, and of mezen in france? has the central nucleus of volcanoes been heated in its primitive position, and raised up, in a softened state, by the force of the elastic vapours, before these fluids communicated, by means of a crater, with the external air? what is the substance, which, for thousands of years, keeps up this combustion, sometimes so slow, and at other times so active? does this unknown cause act at an immense depth; or does this chemical action take place in secondary rocks lying on granite? the farther we are from finding a solution of these problems in the numerous works hitherto published on etna and vesuvius, the greater is the desire of the traveller to see with his own eyes. he hopes to be more fortunate than those who have preceded him; he wishes to form a precise idea of the geological relations which the volcano and the neighbouring mountains bear to each other: but how often is he disappointed, when, on the limits of the primitive soil, enormous banks of tufa and puzzolana render every observation on the position and stratification impossible! we reach the inside of the crater with less difficulty than we at first expect; we examine the cone from its summit to its base; we are struck with the difference in the produce of each eruption, and with the analogy which still exists between the lavas of the same volcano; but, notwithstanding the care with which we interrogate nature, and the number of partial observations which present themselves at every step, we return from the summit of a burning volcano less satisfied than when we were preparing to visit it. it is after we have studied them on the spot, that the volcanic phenomena appear still more isolated, more variable, more obscure, than we imagine them when consulting the narratives of travellers. these reflections occurred to me on descending from the summit of the peak of teneriffe, the first unextinct volcano i had yet visited. they returned anew whenever, in south america, or in mexico, i had occasion to examine volcanic mountains. when we reflect how little the labours of mineralogists, and the discoveries in chemistry, have promoted the knowledge of the physical geology of mountains, we cannot help being affected with a painful sentiment; and this is felt still more strongly by those, who, studying nature in different climates, are more occupied by the problems they have not been able to solve, than with the few results they have obtained. the peak of ayadyrma, or of echeyde,* (* the word echeyde, which signifies hell in the language of the guanches, has been corrupted by the europeans into teyde.) is a conic and isolated mountain, which rises in an islet of very small circumference. those who do not take into consideration the whole surface of the globe, believe, that these three circumstances are common to the greater part of volcanoes. they cite, in support of their opinion, etna, the peak of the azores, the solfatara of guadaloupe, the trois-salazes of the isle of bourbon, and the clusters of volcanoes in the indian sea and in the atlantic. in europe and in asia, as far as the interior of the latter continent is known, no burning volcano is situated in the chains of mountains; all being at a greater or less distance from those chains. in the new world, on the contrary, (and this fact deserves the greatest attention,) the volcanoes the most stupendous for their masses form a part of the cordilleras themselves. the mountains of mica-slate and gneiss in peru and new grenada immediately touch the volcanic porphyries of the provinces of quito and pasto. to the south and north of these countries, in chile and in the kingdom of guatimala, the active volcanoes are grouped in rows. they are the continuation, as we may say, of the chains of primitive rocks, and if the volcanic fire has broken forth in some plain remote from the cordilleras, as in mount sangay and jorullo,* (* two volcanoes of the provinces of quixos and mechoacan, the one in the southern, and the other in the northern hemisphere.) we must consider this phenomenon as an exception to the law, which nature seems to have imposed on these regions. i may here repeat these geological facts, because this presumed isolated situation of every volcano has been cited in opposition to the idea that the peak of teneriffe, and the other volcanic summits of the canary islands, are the remains of a submerged chain of mountains. the observations which have been made on the grouping of volcanoes in america, prove that the ancient state of things represented in the conjectural map of the atlantic by m. bory de st. vincent* (* whether the traditions of the ancients respecting the atlantis are founded on historical facts, is a matter totally distinct from the question whether the archipelago of the canaries and the adjacent islands are the vestiges of a chain of mountains, rent and sunk in the sea during one of the great convulsions of our globe. i do not pretend to form any opinion in favour of the existence of the atlantis; but i endeavour to prove, that the canaries have no more been created by volcanoes, than the whole body of the smaller antilles has been formed by madrepores.) is by no means contradictory to the acknowledged laws of nature; and that nothing opposes the supposition that the summits of porto santo, madeira, and the fortunate islands, may heretofore have formed, either a distinct range of primitive mountains, or the western extremity of the chain of the atlas. the peak of teyde forms a pyramidal mass like etna, tungurahua, and popocatepetl. this physiognomic character is very far from being common to all volcanoes. we have seen some in the southern hemisphere, which, instead of having the form of a cone or a bell, are lengthened in one direction, having the ridge sometimes smooth, and at others bristled with small pointed rocks. this structure is peculiar to antisana and pichincha, two burning mountains of the province of quito; and the absence of the conic form ought never to be considered as a reason excluding the idea of a volcanic origin. i shall develop, in the progress of this work, some of the analogies, which i think i have perceived between the physiognomy of volcanoes and the antiquity of their rocks. it is sufficient to state, generally speaking, that the summits, which are still subject to eruptions of the greatest violence, and at the nearest periods to each other, are slender peaks of a conic form; that the mountains with lengthened summits, and rugged with small stony masses, are very old volcanoes, and near being extinguished; and that rounded tops, in the form of domes, or bells, indicate those problematic porphyries, which are supposed to have been heated in their primitive position, penetrated by vapours, and forced up in a mollified state, without having ever flowed as real lithoidal lavas. to the first class belong cotopaxi, the peak of teneriffe, and the peak of orizava in mexico. in the second may be placed cargueirazo and pichincha, in the province of quito; the volcano of puracey, near popayan; and perhaps also hecla, in iceland. in the third and last we may rank the majestic figure of chimborazo, and, (if it be allowable to place by the side of that colossus a hill of europe,) the great sarcouy in auvergne. in order to form a more exact idea of the external structure of volcanoes, it is important to compare their perpendicular height with their circumference. this, however, cannot be done with any exactness, unless the mountains are isolated, and rising on a plain nearly on a level with the sea. in calculating the circumference of the peak of teneriffe in a curve passing through the port of orotava, garachico, adexe, and guimar, and setting aside the prolongations of its base towards the forest of laguna, and the north-east cape of the island, we find that this extent is more than , toises. the height of the peak is consequently one twenty-eighth of the circumference of its basis. m. von buch found a thirty-third for vesuvius; and, which perhaps is less certain, a thirty-fourth for etna.* (* gilbert, annalen der physik b. page . vesuvius is , palmas, or eighteen nautical miles in circumference. the horizontal distance from resina to the crater is toises. italian mineralogists have estimated the circumference of etna at , palmas, or miles. with these data, the ratio of the height to the circumference would be only a seventy-second; but i find on tracing a curve through catania, palermo, bronte, and piemonte, only miles in circumference, according to the best maps. this increases the ratio to a fifty-fourth. does the basis fall on the outside of the curve that i assume?) if the slope of these three volcanoes were uniform from the summit to the base, the peak of teyde would have an inclination of degrees minutes, vesuvius degrees minutes, and etna degrees minutes, a result which must astonish those who do not reflect on what constitutes an average slope. in a very long ascent, slopes of three or four degrees alternate with others which are inclined from to degrees; and the latter only strike our imagination, because we think all the slopes of mountains more steep than they really are. i may cite in support of this consideration the example of the ascent from the port of vera cruz to the elevated plain of mexico. on the eastern slope of the cordillera a road has been traced, which for ages has not been frequented except on foot, or on the backs of mules. from encero to the small indian village of las vigas, there are toises of horizontal distance; and encero being, according to my barometric measurement, toises lower than las vigas, the result, for the mean slope, is only an angle of degrees minutes. in the following note will be seen the results of some experiments i have made on the difficulties arising from the declivities in mountainous countries.* (* in places where there were at the same time slopes covered with tufted grass and loose sands, i took the following measures:-- degrees, slope of a very marked inclination. in france the high roads must not exceed degrees minutes by law; degrees, slope extremely steep, and which we cannot descend in a carriage; degrees, slope almost inaccessible on foot, if the ground be naked rock, or turf too thick to form steps. the body falls backwards when the tibia makes a smaller angle than degrees with the sole of the foot; degrees, the steepest slope that can be climbed on foot in a ground that is sandy, or covered with volcanic ashes. when the slope is degrees, it is almost impossible to scale it, though the ground permits the forming of steps by thrusting in the foot. the cones of volcanoes have a medium slope from to degrees. the steepest parts of these cones, either of vesuvius, the peak of teneriffe, the volcano of pichincha, or jorullo, are from to degrees. a slope of degrees is quite inaccessible. if seen from above it would be estimated at degrees.) isolated volcanoes, in the most distant regions, are very analogous in their structure. at great elevations all have considerable plains, in the middle of which arises a cone perfectly circular. thus at cotopaxi the plains of suniguaicu extend beyond the farm of pansache. the stony summit of antisana, covered with eternal snow, forms an islet in the midst of an immense plain, the surface of which is twelve leagues square, while its height exceeds that of the peak of teneriffe by two hundred toises. at vesuvius, at three hundred and seventy toises high, the cone detaches itself from the plain of atrio dei cavalli. the peak of teneriffe presents two of these elevated plains, the uppermost of which, at the foot of the piton, is as high as etna, and of very little extent; while the lowermost, covered with tufts of retama, reaches as far as the estancia de los ingleses. this rises above the level of the sea almost as high as the city of quito, and the summit of mount lebanon. the greater the quantity of matter that has issued from the crater of a mountain, the more elevated is its cone of ashes in proportion to the perpendicular height of the volcano itself. nothing is more striking, under this point of view, than the difference of structure between vesuvius, the peak of teneriffe, and pichincha. i have chosen this last volcano in preference, because its summit* enters scarcely within the limit of the perpetual snows. (* i have measured the summit of pichincha, that is the small mountain covered with ashes above the llano del vulcan, to the north of alto de chuquira. this mountain has not, however, the regular form of a cone. as to vesuvius, i have indicated the mean height of the sugar-loaf, on account of the great difference between the two edges of the crater.) the cone of cotopaxi, the form of which is the most elegant and most regular known, is toises in height; but it is impossible to decide whether the whole of this mass is covered with ashes. table : volcanoes: column : name of the volcano. column : total height in toises. column : height of the cone covered with ashes. column : proportion of the cone to the total height. vesuvius : : : / . peak of teneriffe : : : / . pichincha : : : / . this table seems to indicate, what we shall have an opportunity of proving more amply hereafter, that the peak of teneriffe belongs to that group of great volcanoes, which, like etna and antisana, have had more copious eruptions from their sides than from their summits. thus the crater at the extremity of the piton, which is called the caldera, is extremely small. its diminutive size struck m. de borda, and other travellers, who took little interest in geological investigations. as to the nature of the rocks which compose the soil of teneriffe, we must first distinguish between productions of the present volcano, and the range of basaltic mountains which surround the peak, and which do not rise more than five or six hundred toises above the level of the ocean. here, as well as in italy, mexico, and the cordilleras of quito, the rocks of trap-formation* are at a distance from the recent currents of lava (* the trap-formation includes the basalts, green-stone (grunstein), the trappean porphyries, the phonolites or porphyrschiefer, etc.); everything shows that these two classes of substances, though they owe their origin to similar phenomena, date from very different periods. it is important to geology not to confound the modern currents of lava, the heaps of basalt, green-stone, and phonolite, dispersed over the primitive and secondary formations, with those porphyroid masses having bases of compact feldspar,* which perhaps have never been perfectly liquified, but which do not less belong to the domain of volcanoes. (* these petrosiliceous masses contain vitreous and often calcined crystals of feldspar, of amphibole, of pyroxene, a little of olivine, but scarcely any quartz. to this very ambiguous formation belong the trappean porphyries of chimborazo and of riobamba in america, of the euganean mountains in italy, and of the siebengebirge in germany; as well as the domites of the great-sarcouy, of puy-de-dome, of the little cleirsou, and of one part of the puy-chopine in auvergne.) in the island of teneriffe, strata of tufa, puzzolana, and clay, separate the range of basaltic hills from the currents of recent lithoid lava, and from the eruptions of the present volcano. in the same manner as the eruptions of epomeo in the island of ischia, and those of jorullo in mexico, have taken place in countries covered with trappean porphyry, ancient basalt, and volcanic ashes, so the peak of teyde has raised itself amidst the wrecks of submarine volcanoes. notwithstanding the difference of composition in the recent lavas of the peak, there is a certain regularity of position, which must strike the naturalist least skilled in geognosy. the great elevated plain of retama separates the black, basaltic, and earthlike lava, from the vitreous and feldsparry lava, the basis of which is obsidian, pitch-stone, and phonolite. this phenomenon is the more remarkable, inasmuch as in bohemia and in other parts of europe, the porphyrschiefer with base of phonolite* (* klingstein. werner.) covers also the convex summits of basaltic mountains. it has already been observed, that from the level of the sea to portillo, and as far as the entrance on the elevated plain of the retama, that is, two-thirds of the total height of the volcano, the ground is so covered with plants, that it is difficult to make geological observations. the currents of lava, which we discover on the slope of monte verde, between the beautiful spring of dornajito and caravela, are black masses, altered by decomposition, sometimes porous, and with very oblong pores. the basis of these lower lavas is rather wacke than basalt; when it is spongy, it resembles the amygdaloids* of frankfort-on-the-main. (* wakkenartiger mandelstein. steinkaute.) its fracture is generally irregular; wherever it is conchoidal, we may presume that the cooling has been more rapid, and the mass has been exposed to a less powerful pressure. these currents of lava are not divided into regular prisms, but into very thin layers, not very regular in their inclination; they contain much olivine, small grains of magnetic iron, and augite, the colour of which often varies from deep leek-green to olive green, and which might be mistaken for crystallized olivine, though no transition from one to the other of these substances exists.* (* steffens, handbuch der oryktognosie tome s. . the crystals which mr. friesleben and myself have made known under the denomination of foliated olivine (blattriger olivin) belong, according to mr. karsten, to the pyroxene augite. journal des mines de freiberg page .) amphibole is in general very rare at teneriffe, not only in the modern lithoid lavas, but also in the ancient basalts, as has been observed by m. cordier, who resided longer at the canaries than any other mineralogist. nepheline, leucite, idocrase, and meionite have not yet been seen at the peak of teneriffe; for a reddish-grey lava, which we found on the slope of monte verde, and which contains small microscopic crystals, appears to me to be a close mixture of basalt and analcime.* (* this substance, which m. dolomieu discovered in the amygdaloids of catania in sicily, and which accompanies the stilbites of fassa in tyrol, forms, with the chabasie of hauy, the genus cubicit of werner. m. cordier found at teneriffe xeolite in an amygdaloid which covers the basalts of la punta di naga.) in like manner the lava of scala, with which the city of naples is paved, contains a close mixture of basalt, nepheline, and leucite. with respect to this last substance, which has hitherto been observed only at vesuvius and in the environs of rome, it exists perhaps at the peak of teneriffe, in the old currents of lava now covered by more recent ejections. vesuvius, during a long series of years, has also thrown out lavas without leucites: and if it be true, as m. von buch has rendered very probable, that these crystals are formed only in the currents which flow either from the crater itself, or very near its brink, we must not be surprised at not finding them in the lavas of the peak. the latter almost all proceed from lateral eruptions, and consequently have been exposed to an enormous pressure in the interior of the volcano. in the plain of retama, the basaltic lavas disappear under heaps of ashes, and pumice-stone reduced to powder. thence to the summit, from to toises in height, the volcano exhibits only vitreous lava with bases of pitch-stone* (* petrosilex resinite. hauy.) and obsidian. these lavas, destitute of amphibole and mica, are of a blackish brown, often varying to the deepest olive green. they contain large crystals of feldspar, which are not fissured, and seldom vitreous. the analogy of those decidedly volcanic masses with the resinite porphyries* (* pechstein-porphyr. werner.) of the valley of tribisch in saxony is very remarkable; but the latter, which belong to an extended and metalliferous formation of porphyry, often contain quartz, which is wanting in the modern lavas. when the basis of the lavas of the malpays changes from pitchstone to obsidian, its colour is paler, and is mixed with grey; in this case, the feldspar passes by imperceptible gradations from the common to the vitreous. sometimes both varieties meet in the same fragment, as we observed also in the trappean porphyries of the valley of mexico. the feldsparry lavas of the peak, of a much less black tinge than those of arso in the island of ischia, whiten at the edge of the crater from the effect of the acid vapours; but internally they are not found to be colourless like that of the feldsparry lavas of the solfatara at naples, which perfectly resemble the trappean porphyries at the foot of chimborazo. in the middle of the malpays, at the height of the cavern of ice, we found among the vitreous lavas with pitch-stone and obsidian bases, blocks of real greenish-grey, or mountain-green phonolite, with a smooth fracture, and divided into thin laminae, sonorous and keen edged. these masses were the same as the porphyrschiefer of the mountain of bilin in bohemia; we recognised in them small long crystals of vitreous feldspar. this regular disposition of lithoid basaltic lava and feldsparry vitreous lava is analogous to the phenomena of all trappean mountains; it reminds us of those phonolites lying in very ancient basalts, those close mixtures of augite and feldspar which cover the hills of wacke or porous amygdaloids: but why are the porphyritic or feldsparry lavas of the peak found only on the summit of the volcano? should we conclude from this position that they are of more recent formation than the lithoid basaltic lava, which contains olivine and augite? i cannot admit this last hypothesis; for lateral eruptions may have covered the feldsparry nucleus, at a period when the crater had ceased its activity. at vesuvius also, we perceive small crystals of vitreous feldspar only in the very ancient lavas of the somma. these lavas, setting aside the leucite, very nearly resemble the phonolitic ejections of the peak of teneriffe. in general, the farther we go back from the period of modern eruptions, the more the currents increase both in size and extent, acquiring the character of rocks, by the regularity of their position, by their division into parallel strata, or by their independence of the present form of the ground. the peak of teneriffe is, next to lipari, the volcano that has produced most obsidian. this abundance is the more striking, as in other regions of the earth, in iceland, in hungary, in mexico, and in the kingdom of quito, we meet with obsidians only at great distances from burning volcanoes. sometimes they are scattered over the fields in angular pieces; for instance, near popayan, in south america; at other times they form isolated rocks, as at quinche, near quito. in other places (and this circumstance is very remarkable), they are disseminated in pearl-stone, as at cinapecuaro, in the province of mechoacan,* (* to the west of the city of mexico.) and at the cabo de gates, in spain. at the peak of teneriffe the obsidian is not found towards the base of the volcano, which is covered with modern lava: it is frequent only towards the summit, especially from the plain of retama, where very fine specimens may be collected. this peculiar position, and the circumstance that the obsidian of the peak has been ejected by a crater which for ages past has thrown out no flames, favour the opinion, that volcanic vitrifications, wherever they are found, are to be considered as of very ancient formation. obsidian, jade, and lydian-stone,* (* lydischerstein.) are three minerals, which nations ignorant of the use of copper or iron, have in all ages employed for making keen-edged weapons. we see that wandering hordes have dragged with them, in their distant journeys, stones, the natural position of which the mineralogist has not yet been able to determine. hatchets of jade, covered with aztec hieroglyphics, which i brought from mexico, resemble both in their form and nature those made use of by the gauls, and those we find among the south sea islanders. the mexicans dug obsidian from mines, which were of vast extent; and they employed it for making knives, sword-blades, and razors. in like manner the guanches, (in whose language obsidian was called tabona,) fixed splinters of that mineral to the ends of their lances. they carried on a considerable trade in it with the neighbouring islands; and from the consumption thus occasioned, and the quantity of obsidian which must have been broken in the course of manufacture, we may presume that this mineral has become scarce from the lapse of ages. we are surprised to see an atlantic nation substituting, like the natives of america, vitrified lava for iron. in both countries this variety of lava was employed as an object of ornament: and the inhabitants of quito made beautiful looking-glasses with an obsidian divided into parallel laminae. there are three varieties of obsidian at the peak. some form enormous blocks, several toises long, and often of a spheroidal shape. we might suppose that they had been thrown out in a softened state, and had afterwards been subject to a rotary motion. they contain a quantity of vitreous feldspar, of a snow-white colour, and the most brilliant pearly lustre. these obsidians are, nevertheless, but little transparent on the edges; they are almost opaque, of a brownish black, and of an imperfect conchoidal fracture. they pass into pitch-stone; and we may consider them as porphyries with a basis of obsidian. the second variety is found in fragments much less considerable. it is in general of a greenish black, sometimes of murky grey, very seldom of a perfect black, like the obsidian of hecla and mexico. its fracture is perfectly conchoidal, and it is extremely transparent on the edges. i have found in it neither amphibole nor pyroxene, but some small white points, which seem to be feldspar. none of the obsidians of the peak appear in those grey masses of pearl or lavender-blue, striped, and in separate wedge-formed pieces, like the obsidian of quito, mexico, and lipari, and which resemble the fibrous plates of the crystalites of our glass-houses, on which sir james hall, dr. thompson, and m. de bellevue, have published some curious observations.* (* the name crystalites has been given to the crystalized thin plates observed in glass cooling slowly. the term glastenized glass is employed by dr. thompson and others to indicate glass which by slow cooling is wholly unvitrified, and has assumed the appearance of a fossil substance, or real glass-stone.) the third variety of obsidian of the peak is the most remarkable of the whole, from its connexion with pumice-stone. it is, like that above described, of a greenish black, sometimes of a murky grey, but its very thin plates alternate with layers of pumice-stone. dr. thomson's fine collection at naples contained similar examples of lithoid lava of vesuvius, divided into very distinct plates, only a line thick. the fibres of the pumice-stone of the peak are very seldom parallel to each other, and perpendicular to the strata of obsidian; they are most commonly irregular, asbestoidal, like fibrous glass-gall; and instead of being disseminated in the obsidian, like crystalites, they are found simply adhering to one of the external surfaces of this substance. during my stay at madrid, m. hergen showed me several specimens in the mineralogical collection of don jose clavijo; and for a long time the spanish mineralogists considered them as furnishing undoubted proofs, that pumice-stone owes its origin to obsidian, in some degree deprived of colour, and swelled by volcanic fire. i was formerly of this opinion, which, however, must be understood to refer to one variety only of pumice. i even thought, with many other geologists, that obsidian, so far from being vitrified lava, belonged to rocks that were not volcanic; and that the fire, forcing its way through the basalts, the green-stone rocks, the phonolites, and the porphyries with bases of pitchstone and obsidian, the lavas and pumice-stone were no other than these same rocks altered by the action of the volcanoes. the deprivation of colour and extraordinary swelling which the greater part of the obsidians undergo in a forge-fire, their transition into pitch-stone, and their position in regions very distant from burning volcanoes, appear to be phenomena very difficult to reconcile, when we consider the obsidians as volcanic glass. a more profound study of nature, new journeys, and observations made on the productions of burning volcanoes, have led me to renounce those ideas. it appears to me at present extremely probable, that obsidians, and porphyries with bases of obsidian, are vitrified masses, the cooling of which has been too rapid to change them into lithoid lava. i consider even the pearlstone as an unvitrified obsidian: for among the minerals in the king's cabinet at berlin there are volcanic glasses from lipari, in which we see striated crystalites, of a pearl-grey colour, and of an earthy appearance, forming gradual approaches to a granular lithoid lava, like the pearlstone of cinapecuaro, in mexico. the oblong bubbles observed in the obsidians of every continent are incontestible proofs of their ancient state of igneous fluidity; and dr. thompson possesses specimens from lipari, which are very instructive in this point of view, because fragments of red porphyry, or porphyry lavas, which do not entirely fill up the cavities of the obsidian, are found enveloped in them. we might say, that these fragments had not time to enter into complete solution in the liquified mass. they contain vitreous feldspar, and augite, and are the same as the celebrated columnar porphyries of the island of panaria, which, without having been part of a current of lava, seem raised up in the form of hillocks, like many of the porphyries in auvergne, in the euganean mountains, and in the cordilleras of the andes. the objections against the volcanic origin of obsidians, founded on their speedy loss of colour, and their swelling by a slow fire, have been shaken by the ingenious experiments of sir james hall. these experiments prove, that a stone which is fusible only at thirty-eight degrees of wedgwood's pyrometer, yields a glass that softens at fourteen degrees; and that this glass, melted again and unvitrified (glastenized), is fusible again only at thirty-five degrees of the same pyrometer. i applied the blowpipe to some black pumice-stone from the volcano of the isle of bourbon, which, on the slightest contact with the flame, whitened and melted into an enamel. but whether obsidians be primitive rocks which have undergone the action of volcanic fire, or lavas repeatedly melted within the crater, the origin of the pumice-stones contained in the obsidian of the peak of teneriffe is not less problematic. this subject is the more worthy of being investigated, since it is generally interesting to the geology of volcanoes; and since that excellent mineralogist, m. fleuriau de bellevue, after having examined italy and the adjacent islands with great attention, affirms, that it is highly improbable that pumice-stone owes its origin to the swelling of obsidian. the experiments of m. da camara, and those i made in , tend to support the opinion, that the pumice-stones adherent to the obsidians of the peak of teneriffe do not unite to them accidentally, but are produced by the expansion of an elastic fluid, which is disengaged from the compact vitreous matter. this idea had for a long time occupied the mind of a person highly distinguished for his talents and reputation at quito, who, unacquainted with the labours of the mineralogists of europe, had devoted himself to researches on the volcanoes of his country. don juan de larea, one of those men lately sacrificed to the fury of faction, had been struck with the phenomena exhibited by obsidians exposed to a white heat. he had thought, that, wherever volcanoes act in the centre of a country covered with porphyry with base of obsidian, the elastic fluids must cause a swelling of the liquified mass, and perform an important part in the earthquakes preceding eruptions. without adopting an opinion, which seems somewhat bold, i made, in concert with m. larea, a series of experiments on the tumefaction of the volcanic vitreous substances at teneriffe, and on those which are found at quinche, in the kingdom of quito. to judge of the augmentation of their bulk, we measured pieces exposed to a forge-fire of moderate heat, by the water they displaced from a cylindric glass, enveloping the spongy mass with a thin coating of wax. according to our experiments, the obsidians swelled very unequally: those of the peak and the black varieties of cotopaxi and of quinche increased nearly five times their bulk. the colour of the pumice-stones of the peak leads to another important observation. the sea of white ashes which encircles the piton, and covers the vast plain of retama, is a certain proof of the former activity of the crater: for in all volcanoes, even when there are lateral eruptions, the ashes and the rapilli issue conjointly with the vapours only from the opening at the summit of the mountain. now, at teneriffe, the black rapilli extend from the foot of the peak to the sea-shore; while the white ashes, which are only pumice ground to powder, and among which i have discovered, with a lens, fragments of vitreous feldspar and pyroxene, exclusively occupy the region next to the peak. this peculiar distribution seems to confirm the observations made long ago at vesuvius, that the white ashes are thrown out last, and indicate the end of the eruption. in proportion as the elasticity of the vapours diminishes, the matter is thrown to a less distance; and the black rapilli, which issue first, when the lava has ceased running, must necessarily reach farther than the white rapilli. the latter appear to have been exposed to the action of a more intense fire. i have now examined the exterior structure of the peak, and the composition of its volcanic productions, from the region of the coast to the top of the piton:--i have endeavoured to render these researches interesting, by comparing the phenomena of the volcano of teneriffe with those that are observed in other regions, the soil of which is equally undermined by subterranean fires. this mode of viewing nature in the universality of her relations is no doubt adverse to the rapidity desirable in an itinerary; but it appears to me that, in a narrative, the principal end of which is the progress of physical knowledge, every other consideration ought to be subservient to those of instruction and utility. by isolating facts, travellers, whose labours are in every other respect valuable, have given currency to many false ideas of the pretended contrasts which nature offers in africa, in new holland, and on the ridge of the cordilleras. the great geological phenomena are subject to regular laws, as well as the forms of plants and animals. the ties which unite these phenomena, the relations which exist between the varied forms of organized beings, are discovered only when we have acquired the habit of viewing the globe as a great whole; and when we consider in the same point of view the composition of rocks, the causes which alter them, and the productions of the soil, in the most distant regions. having treated of the volcanic substances of the isle of teneriffe, there now remains to be solved a question intimately connected with the preceding investigation. does the archipelago of the canary islands contain any rocks of primitive or secondary formation; or is there any production observed, that has not been modified by fire? this interesting problem has been considered by the naturalists of lord macartney's expedition, and by those who accompanied captain baudin in his voyage to the austral regions. their opinions are in direct opposition to each other; and the contradiction is the more striking, as the question does not refer to one of those geological reveries which we are accustomed to call systems, but to a positive fact. doctor gillan imagined that he observed, between laguna and the port of orotava, in very deep ravines, beds of primitive rocks. this, however, is a mistake. what dr. gillan calls somewhat vaguely, mountains of hard ferruginous clay, are nothing but an alluvium which we find at the foot of every volcano. strata of clay accompany basalts, as tufas accompany modern lavas. neither m. cordier nor myself observed in any part of teneriffe a primitive rock, either in its natural place, or thrown out by the mouth of the peak; and the absence of these rocks characterizes almost every island of small extent that has an unextinguishied volcano. we know nothing positive of the mountains of the azores; but it is certain, that the island of bourbon as well as teneriffe, exhibits only a heap of lavas and basalts. no volcanic rock rears its head, either on the gros morne, or on the volcano of bourbon, or on the colossal pyramid of cimandef, which is perhaps more elevated than the peak of the canary islands. bory st. vincent nevertheless asserted, that lavas including fragments of granite have been found on the elevated plain of retama; and m. broussonnet informed me, that on a hill above guimar, fragments of mica-slate, containing beautiful plates of specular iron, had been found. i can affirm nothing respecting the accuracy of this latter statement, which it would be so much the more important to verify, as m. poli, of naples, is in possession of a fragment of rock thrown out by vesuvius,* which i found to be a real mica-slate. (* in the valuable collection of dr. thomson, who resided at naples till , is a fragment of lava enclosing a real granite, which is composed of reddish feldspar with a pearly lustre like adularia, quartz, mica, hornblende, and, what is very remarkable, lazulite. but in general the masses of known primitive rocks, (i mean those which perfectly resemble our granites, our gneiss, and our mica-slates) are very rare in lavas; the substances we commonly denote by the name of granite, thrown out by vesuvius, are mixtures of nepheline, mica, and pyroxene. we are ignorant whether these mixtures constitute rocks sui generis placed under granite, and consequently of more ancient date; or simply form either intermediate strata on veins, in the interior of the primitive mountains, the tops of which appear at the surface of the globe.) every thing that tends to enlighten us with respect to the site of the volcanic fire, and the position of rocks subject to its action, is highly interesting to geology. it is possible, that at the peak of teneriffe, the fragments of primitive rocks thrown out by the mouth of the volcano may be less rare than they at present appear to be, and may be heaped together in some ravine, not yet visited by travellers. in fact, at vesuvius, these same fragments are met with only in one single place, at the fossa grande, where they are hidden under a thick layer of ashes. if this ravine had not long ago attracted the attention of naturalists, when masses of granular limestone, and other primitive rocks, were laid bare by the rains, we might have thought them as rare at vesuvius, as they are, at least in appearance, at the peak of teneriffe. with respect to the fragments of granite, gneiss, and mica-slate, found on the shores of santa cruz and orotava, they were probably brought in ships as ballast. they no more belong to the soil where they lie, than the feldsparry lavas of etna, seen in the pavements of hamburg and other towns of the north. the naturalist is exposed to a thousand errors, if he lose sight of the changes, produced on the surface of the globe by the intercourse between nations. we might be led to say, that man, when expatriating himself; is desirous that everything should change country with him. not only plants, insects, and different species of small quadrupeds, follow him across the ocean; his active industry covers the shores with rocks, which he has torn from the soil in distant climes. though it be certain, that no scientific observer has hitherto found at teneriffe primitive strata, or even those trappean and ambiguous porphyries, which constitute the bases of etna, and of several volcanoes of the andes, we must not conclude from this isolated fact, that the whole archipelago of the canaries is the production of submarine fires. the island of gomera contains mountains of granite and mica-slate; and it is, undoubtedly, in these very ancient rocks, that we must seek there, as well as on all other parts of the globe, the centre of the volcanic action. amphibole, sometimes pure and forming intermediate strata, at other times mixed with granite, as in the basanites or basalts of the ancients, may, of itself, furnish all the iron contained in the black and stony lavas. this quantity amounts in the basalt of the modern mineralogists only to . , while in amphibole it exceeds . . from several well-informed persons, to whom i addressed myself, i learned that there are calcareous formations in the great canary, forteventura, and lancerota.* (* at lancerota calcareous stone is burned to lime with a fire made of the alhulaga, a new species of thorny and arborescent sonchus.) i was not able to determine the nature of this secondary rock; but it appears certain, that the island of teneriffe is altogether destitute of it; and that in its alluvial lands it exhibits only clayey calcareous tufa, alternating with volcanic breccia, said to contain, (near the village of la rambla, at calderas, and near candelaria,) plants, imprints of fishes, buccinites, and other fossil marine productions. m. cordier brought away some of this tufa, which resembles that in the environs of naples and rome, and contains fragments of reeds. at the salvages, which islands la perouse took at a distance for masses of scoriae, even fibrous gypsum is found. i had seen, while herborizing between the port of orotava and the garden of la paz, heaps of greyish calcareous stones, of an imperfect conchoidal fracture, and analogous to that of mount jura and the apennines. i was informed that these stones were extracted from a quarry near rambla; and that there were similar quarries near realejo, and the mountain of roxas, above adexa. this information led me into an error. as the coasts of portugal consist of basalts covering calcareous rocks containing shells, i imagined that a trappean formation, like that of the vicentin in lombardy, and of harutsh in africa, might have extended from the banks of the tagus and cape st. vincent as far as the canary islands; and that the basalts of the peak might perhaps conceal a secondary calcareous stone. these conjectures exposed me to severe animadversions from m. g.a. de luc, who is of opinion that every volcanic island is only an accumulation of lavas and scoriae. m. de luc declares it is impossible that real lava should contain fragments of vegetable substances. our collections, however, contain pieces of trunks of palm-trees, enclosed and penetrated by the very liquid lava of the isle of bourbon. though teneriffe belongs to a group of islands of considerable extent, the peak exhibits nevertheless all the characteristics of a mountain rising on a solitary islet. the lead finds no bottom at a little distance from the ports of santa cruz, orotava, and garachico: in this respect it is like st. helena. the ocean, as well as the continents, has its mountains and its plains; and, if we except the andes, volcanic cones are formed everywhere in the lower regions of the globe. as the peak rises amid a system of basalts and old lava, and as the whole part which is visible above the surface of the waters exhibits burnt substances, it has been supposed that this immense pyramid is the effect of a progressive accumulation of lavas; or that it contains in its centre a nucleus of primitive rocks. both of these suppositions appear to me ill-founded. i think there is as little probability that mountains of granite, gneiss, or primitive calcareous stone have existed where we now see the tops of the peak, of vesuvius, and of etna, as in the plains where almost in our own time has been formed the volcano of jorullo, which is more than a third of the height of vesuvius. on examining the circumstances which accompanied the formation of the new island, called sabrina, in the archipelago of the azores;* (* at sabrina island, near st. michael's, the crater opened at the foot of a solid rock, of almost a cubical form. this rock, surmounted by a small elevated plain perfectly level, is more than two hundred toises in breadth. its formation was anterior to that of the crater, into which, a few days after its opening, the sea made an irruption. at kameni, the smoke was not even visible till twenty-six days after the appearance of the upheaved rocks. philosophical transactions volume pages and , volume page . all these phenomena, on which mr. hawkins collected very valuable observations during his abode at santorino, are unfavourable to the idea commonly entertained of the origin of volcanic mountains. they are usually ascribed to a progressive accumulation of liquified matter, and the diffusion of lavas issuing from a central mouth.) on carefully reading the minute and simple narrative, given by the jesuit bourguignon of the slow appearance of the islet of the little kameni, near santorino; we find that these extraordinary eruptions are generally preceded by a swelling of the softened crust of the globe. rocks appear above the waters before the flames force their way, or lavas issue from the crater: we must distinguish between the nucleus raised up, and the mass of lavas and scoriae, which successively increases its dimensions. it is true that from all existing records of revolutions of this kind, the perpendicular height of the stony nucleus appears never to have exceeded one hundred and fifty or two hundred toises; even taking into the account the depth of the sea, the bottom of which had been lifted up: but when considering the great effects of nature, and the intensity of its forces, the bulk of the masses must not deter the geologist in his speculations. every thing indicates that the physical changes of which tradition has preserved the remembrance, exhibit but a feeble image of those gigantic catastrophes which have given mountains their present form, changed the positions of the rocky strata, and buried sea-shells on the summits of the higher alps. doubtless, in those remote times which preceded the existence of the human race, the raised crust of the globe produced those domes of trappean porphyry, those hills of isolated basalt on vast elevated plains, those solid nuclei which are clothed in the modern lavas of the peak, of etna, and of cotopaxi. the volcanic revolutions have succeeded each other after long intervals, and at very different periods: of this we see the vestiges in the transition mountains, in the secondary strata, and in those of alluvium. volcanoes of earlier date than the sandstone and calcareous rocks have been for ages extinguished; those which are yet in activity are in general surrounded only with breccias and modern tufas; but nothing hinders us from admitting, that the archipelago of the canaries may exhibit some real rocks of secondary formation, if we recollect that subterranean fires have been there rekindled in the midst of a system of basalts and very ancient lavas. we seek in vain in the periplus of hanno or of scylax for the first written notions on the eruptions of the peak of teneriffe. those navigators sailed timidly along the coast, anchoring every evening in some bay, and had no knowledge of a volcano distant fifty-six leagues from the coast of africa. hanno nevertheless relates, that he saw torrents of light, which seemed to fall on the sea; that every night the coast was covered with fire; and that the great mountain, called the car of the gods, appeared to throw up sheets of flame, which rose even to the clouds. but this mountain, situated northward of the island of the gorilli, formed the western extremity of the atlas chain; and it is also very uncertain whether the flames seen by hanno were the effect of some volcanic eruption, or whether they must be attributed to the custom, common to many nations, of setting fire to the forests and dry grass of the savannahs. in our own days similar doubts were entertained by the naturalists, who, in the voyage of d'entrecasteaux, saw the island of amsterdam covered with a thick smoke. on the coast of the caracas, trains of reddish fire, fed by the burning grass, appeared to me, for several nights, under the delusive semblance of a current of lava, descending from the mountains, and dividing itself into several branches. though the narratives of hanno and scylax, in the state in which they have reached us, contain no passage which we can reasonably apply to the canary islands, it is very probable that the carthaginians, and even the phoenicians, had some knowledge of the peak of teneriffe. in the time of plato and aristotle, vague notions of it had reached the greeks, who considered the whole of the coast of africa, beyond the pillars of hercules, as thrown into disorder by the fire of volcanoes. the abode of the blessed, which was sought first in the north, beyond the riphaean mountains, among the hyperboreans, and next to the south of cyrenaica, was supposed to be situated in regions that were considered to be westward, being the direction in which the world known to the ancients terminated. the name of fortunate islands was long in as vague signification, as that of el dorado among the conquerors of america. happiness was thought to reside at the end of the earth, as we seek for the most exquisite enjoyments of the mind in an ideal world beyond the limits of reality.* (* the idea of the happiness, the great civilization, and the riches of the inhabitants of the north, was common to the greeks, to the people of india, and to the mexicans.) we must not be surprised that, previous to the time of aristotle, we find no accurate notion respecting the canary islands and the volcanoes they contain, among the greek geographers. the only nation whose navigations extended toward the west and the north, the carthaginians, were interested in throwing a veil of mystery over those distant regions. while the senate of carthage was averse to any partial emigration, it pointed out those islands as a place of refuge in times of trouble and public misfortune; they were to the carthaginians what the free soil of america has become to europeans amidst their religious and civil dissensions. the canaries were not better known to the romans till eighty-four years before the reign of augustus. a private individual was desirous of executing the project, which wise foresight had dictated to the senate of carthage. sertorius, conquered by sylla, and weary of the din of war, looked out for a safe and peaceable retreat. he chose the fortunate islands, of which a delightful picture had been drawn for him on the shores of baetica. he carefully combined the notions he acquired from travellers; but in the little that has been transmitted to us of those notions, and in the more minute descriptions of sebosus and juba, there is no mention of volcanoes or volcanic eruptions. scarcely can we recognise the isle of teneriffe, and the snows with which the summit of the peak is covered in winter, in the name of nivaria, given to one of the fortunate islands. hence we might conclude, that the volcano at that time threw out no flames, if it were allowable so to interpret the silence of a few authors, whom we know only by short fragments or dry nomenclatures. the naturalist vainly seeks in history for documents of the first eruptions of the peak; he nowhere finds any but in the language of the guanches, in which the word echeyde denotes, at the same time, hell and the volcano of teneriffe. of all the written testimonies, the oldest i have found in relation to the activity of this volcano dates from the beginning of the sixteenth century. it is contained in the narrative of the voyage of aloysio cadamusto, who landed at the canaries in . this traveller was witness of no eruptions, but he positively affirms that, like etna, this mountain burns without interruption, and that the fire has been seen by christians held in slavery by the guanches of teneriffe. the peak, therefore, was not at that time in the state of repose in which we find it at present; for it is certain that no navigator or inhabitant of teneriffe has seen issue from the mouth of the peak, i will not say flames, but even any smoke visible at a distance. it would be well, perhaps, were the funnel of the caldera to open anew; the lateral eruptions would thereby be rendered less violent, and the whole group of islands would be less endangered by earthquakes. the eruptions of the peak have been very rare for two centuries past, and these long intervals appear to characterize volcanoes highly elevated. the smallest one of all, stromboli, is almost always burning. at vesuvius, the eruptions are rarer than formerly, though still more frequent than those of etna and the peak of teneriffe. the colossal summits of the andes, cotopaxi and tungurahua, scarcely have an eruption once in a century. we may say, that in active volcanoes the frequency of the eruptions is in the inverse ratio of the height and the mass. the peak also had seemed extinguished during ninety-two years, when, in , it made its last eruption by a lateral opening formed in the mountain of chahorra. in this interval vesuvius had sixteen eruptions. the whole of the mountainous part of the kingdom of quito may be considered as an immense volcano, occupying more than seven hundred square leagues of surface, and throwing out flames by different cones, known under the particular denominations of cotopaxi, tungurahua, and pichincha. the group of the canary islands is situated on the same sort of submarine volcano. the fire makes its way sometimes by one and sometimes by another of these islands. teneriffe alone contains in its centre an immense pyramid terminating in a crater, and throwing out, from one century to another, lava by its flanks. in the other islands, the different eruptions have taken place in various parts; and we nowhere find those isolated mountains to which the volcanic effects are confined. the basaltic crust, formed by ancient volcanoes, seems everywhere undermined; and the currents of lava, seen at lancerota and palma, remind us, by every geological affinity, of the eruption which took place in at the island of ischia, amid the tufas of epomeo. the exclusively lateral action of the peak of teneriffe is a geological phenomenon, the more remarkable as it contributes to make the mountains which are backed by the principal volcano appear isolated. it is true, that in etna and vesuvius the great flowings of lava do not proceed from the crater itself, and that the abundance of melted matter is generally in the inverse ratio of the height of the opening whence the lava is ejected. but at vesuvius and etna a lateral eruption constantly terminates by flashes of flame and by ashes issuing from the crater, that is, from the summit of the mountain. at the peak this phenomenon has not been witnessed for ages: and yet recently, in the eruption of , the crater remained quite inactive. its bottom did not sink in; while at vesuvius, as m. von buch has observed, the greater or less depth of the crater is an infallible indication of the proximity of a new eruption. i might terminate these geological sketches by enquiring into the nature of the combustible which has fed for so many thousands of years the fire of the peak of teneriffe;--i might examine whether it be sodium or potassium, the metallic basis of some earth, carburet of hydrogen, or pure sulphur combined with iron, that burns in the volcano;--but wishing to limit myself to what may be the object of direct observation, i shall not take upon me to solve a problem for which we have not yet sufficient data. we know not whether we may conclude, from the enormous quantity of sulphur contained in the crater of the peak, that it is this substance which keeps up the heat of the volcano; or whether the fire, fed by some combustible of an unknown nature, effects merely the sublimation of the sulphur. what we learn from observation is, that in craters which are still burning, sulphur is very rare; while all the ancient volcanoes end in becoming sulphur-pits. we might presume that, in the former, the sulphur is combined with oxygen, while, in the latter, it is merely sublimated; for nothing hitherto authorises us to admit that it is formed in the interior of volcanoes, like ammonia and the neutral salts. when we were yet unacquainted with sulphur, except as disseminated in the muriatiferous gypsum and in the alpine limestone, we were almost forced to the belief, that in every part of the globe the volcanic fire acted on rocks of secondary formation; but recent observations have proved that sulphur exists in great abundance in those primitive rocks which so many phenomena indicate as the centre of the volcanic action. near alausi, at the back of the andes of quito, i found an immense quantity in a bed of quartz, which formed a layer of mica-slate. this fact is the more important, as it is in strict conformity with the conclusions deduced from the observation of those fragments of ancient rocks which are thrown out intact by volcanoes. we have just considered the island of teneriffe merely in a geological point of view; we have seen the peak towering amid fractured strata of basalt and mandelstein; let us examine how these fused masses have been gradually adorned with vegetable clothing, what is the distribution of plants on the steep declivity of the volcano, and what is the aspect or physiognomy of vegetation in the canary islands. in the northern part of the temperate zone, the cryptogamous plants are the first that cover the stony crust of the globe. the lichens and mosses, that develop their foliage beneath the snows, are succeeded by grumina and other phanerogamous plants. this order of vegetation differs on the borders of the torrid zone, and in the countries between the tropics. we there find, it is true, whatever some travellers may have asserted, not only on the mountains, but also in humid and shady places, almost on a level with the sea, funaria, dicranum, and bryum; and these genera, among their numerous species, exhibit several which are common to lapland, to the peak of teneriffe, and to the blue mountains of jamaica. (this extraordinary fact was first observed by m. swarz. it was confirmed by m. willdenouw when he carefully examined our herbals, especially the collection of cryptogamous plants, which we gathered on the tops of the andes, in a region of the world where organic life is totally different from that of the old world.) nevertheless, in general, it is not by mosses and lichens that vegetation in the countries near the tropics begins. in the canary islands, as well as in guinea, and on the rocky coasts of peru, the first vegetation which prepares the soil are the succulent plants; the leaves of which, provided with an infinite number of orifices* (* the pores corticaux of m. decandolle, discovered by gleichen, and figured by hedwig.) and cutaneous vessels, deprive the ambient air of the water it holds in solution. fixed in the crevices of volcanic rocks, they form, as it were, that first layer of vegetable earth with which the currents of lithoid lava are clothed. wherever these lavas are scorified, and where they have a shining surface, as in the basaltic mounds to the north of lancerota, the development of vegetation is extremely slow, and many ages may pass away before shrubs can take root. it is only when lavas are covered with tufa and ashes, that the volcanic islands, losing that appearance of nudity which marks their origin, bedeck themselves in rich and brilliant vegetation. in its present state, the island of teneriffe, the chinerfe* (* of chinerfe the europeans have formed, by corruption, tchineriffe and teneriffe.) of the guanches, exhibits five zones of plants, which we may distinguish by the names--region of vines, region of laurels, region of pines, region of the retama, and region of grasses. these zones are ranged in stages, one above another, and occupy, on the steep declivity of the peak, a perpendicular height of toises; while fifteen degrees farther north, on the pyrenees, snow descends to thirteen or fourteen hundred toises of absolute elevation. if the plants of teneriffe do not reach the summit of the volcano, it is not because the perpetual snow and the cold of the surrounding atmosphere mark limits which they cannot pass; it is the scorified lava of the malpays, the powdered and barren pumice-stone of the piton, which impede the migration of plants towards the brink of the crater. the first zone, that of the vines, extends from the sea-shore to two or three hundred toises of height; it is that which is most inhabited, and the only part carefully cultivated. in the low regions, at the port of orotava, and wherever the winds have free access, the centigrade thermometer stands in winter, in the months of january and february, at noon, between fifteen and seventeen degrees; and the greatest heats of summer do not exceed twenty-five or twenty-six degrees. the mean temperature of the coasts of teneriffe appears at least to rise to twenty-one degrees ( . degrees reaumur); and the climate in those parts keeps at the medium between the climate of naples and that of the torrid zone. the region of the vines exhibits, among its vegetable productions, eight kinds of arborescent euphorbia; mesembrianthema, which are multiplied from the cape of good hope to the peloponnesus; the cacalia kleinia, the dracaena, and other plants, which in their naked and tortuous trunks, in their succulent leaves, and their tint of bluish green, exhibit distinctive marks of the vegetation of africa. it is in this zone that the date-tree, the plantain, the sugar-cane, the indian fig, the arum colocasia, the root of which furnishes a nutritive fecula, the olive-tree, the fruit trees of europe, the vine, and corn are cultivated. corn is reaped from the end of march to the beginning of may: and the culture of the bread-fruit tree of otaheite, that of the cinnamon tree of the moluccas, the coffee-tree of arabia, and the cacao-tree of america, have been tried with success. on several points of the coast the country assumes the character of a tropical landscape; and we perceive that the region of the palms extends beyond the limits of the torrid zone. the chamaerops and the date-tree flourish in the fertile plains of murviedro, on the coasts of genoa, and in provence, near antibes, between the thirty-ninth and forty-fourth degrees of latitude; a few trees of the latter species, planted within the walls of the city of rome, resist even the cold of . degrees below freezing point. but if the south of europe as yet only partially shares the gifts lavished by nature on the zone of palms, the island of teneriffe, situated on the parallel of egypt, southern persia, and florida, is adorned with the greater part of the vegetable forms which add to the majesty of the landscape in the regions near the equator. on reviewing the different tribes of indigenous plants, we regret not finding trees with small pinnated leaves, and arborescent gramina. no species of the numerous family of the sensitive-plants has migrated as far as the archipelago of the canary islands, while on both continents they have been seen in the thirty-eighth and fortieth degrees of latitude. on a more careful examination of the plants of the islands of lancerota and forteventura, which are nearest the coast of morocco, we may perhaps find a few mimosas among many other plants of the african flora. the second zone, that of the laurels, comprises the woody part of teneriffe: this is the region of the springs, which gush forth amidst turf always verdant, and never parched with drought. lofty forests crown the hills leading to the volcano, and in them are found four species of laurel,* (* laurus indica, l. foetens, l. nobilis, and l. til. with these trees are mingled the ardisia excelsa, rhamnus glandulosus, erica arborea and e. texo.) an oak nearly resembling the quercus turneri* (* quercus canariensis, broussonnet.) of the mountains of tibet, the visnea mocanera, the myrica faya of the azores, a native olive (olea excelsa), which is the largest tree of this zone, two species of sideroxylon, the leaves of which are extremely beautiful, the arbutus callicarpa, and other evergreen trees of the family of myrtles. bindweeds, and an ivy very different from that of europe (hedera canariensis) entwine the trunks of the laurels; at their feet vegetate a numberless quantity of ferns,* (* woodwardia radicans, asplenium palmatum, a. canariensis, a. latifolium, nothalaena subcordata, trichomanes canariensis, t. speciosum, and davallia canariensis.) of which three species* (* two acrostichums and the ophyoglossum lusitanicum.) alone descend as low as the region of the vines. the soil, covered with mosses and tender grass, is enriched with the flowers of the campanula aurea, the chrysanthemum pinnatifidum, the mentha canariensis, and several bushy species of hypericum.* (* hypericum canariense, h. floribundum, and h. glandulosum.) plantations of wild and grafted chestnut-trees form a broad border round the region of the springs, which is the greenest and most agreeable of the whole. in the third zone (beginning at nine hundred toises of absolute height), the last groups of arbutus, of myrica faya, and of that beautiful heath known to the natives by the name of texo, appear. this zone, four hundred toises in breadth, is entirely filled by a vast forest of pines, among which mingles the juniperus cedro of broussonnet. the leaves of these pines are very long and stiff, and they sprout sometimes by pairs, but oftener by threes in one sheath. having had no opportunity of examining the fructification, we cannot say whether this species, which has the appearance of the scotch fir, is really different from the eighteen species of pines with which we are already acquainted in europe. m. decandolle is of opinion that the pine of teneriffe is equally distinct from the pinus atlantica of the neighbouring mountains of mogador, and from the pine of aleppo,* (* pinus halepensis. m. decandolle observes, that this species, which is not found in portugal, but grows on the mediterranean shores of france, spain, and italy, in asia minor, and in barbary, would be better named pinus mediterranea. it composes the principal part of the pine-forests of the south-east of france, where gouan and gerard have confounded it with the pinus sylvestris. it comprehends the pinus halepensis, mill., lamb., and desfont., and the pinus maritima, lamb.) which belongs to the basin of the mediterranean, and does not appear to have passed the pillars of hercules. we met with these last pines on the slope of the peak, near twelve hundred toises above the level of the sea. in the cordilleras of new spain, under the torrid zone, the mexican pines extend to the height of two thousand toises. notwithstanding the similarity of structure existing between the different species of the same genus of plants, each of them requires a certain degree of temperature and rarity in the ambient air to attain its due growth. if in temperate climates, and wherever snow falls, the uniform heat of the soil be somewhat above the mean heat of the atmosphere, it is probable that at the height of portillo the roots of the pines draw their nourishment from a soil, in which, at a certain depth, the thermometer rises at most to nine or ten degrees. the fourth and fifth zones, the regions of the retama and the gramina, occupy heights equal to the most inaccessible summits of the pyrenees. it is the sterile part of the island where heaps of pumice-stone, obsidian, and broken lava, form impediments to vegetation. we have already spoken of those flowery tufts of alpine broom (spartium nubigenum), which form oases amidst a vast desert of ashes. two herbaceous plants, the scrophularia glabrata and the viola cheiranthifolia, advance even to the malpays. above a turf scorched by the heat of an african sun, an arid soil is overspread by the cladonia paschalis. towards the summit of the peak the urceolarea and other plants of the family of the lichens, help to work the decomposition of the scorified matter. by this unceasing action of organic force the empire of flora is extended over islands ravaged by volcanoes. on surveying the different zones of the vegetation of teneriffe, we perceive that the whole island may be considered as a forest of laurels, arbutus, and pines, containing in its centre a naked and rocky soil, unfit either for pasturage or cultivation. m. broussonnet observes, that the archipelago of the canaries may be divided into two groups of islands; the first comprising lancerota and forteventura, the second teneriffe, canary, gomera, ferro, and palma. the appearance of the vegetation essentially differs in these two groups. the eastern islands, lancerota and forteventura, consist of extensive plains and mountains of little elevation; they have very few springs, and bear the appearance, still more than the other islands, of having been separated from the continent. the winds blow in the same direction, and at the same periods: the euphorbia mauritanica, the atropa frutescens, and the arborescent sonchus, vegetate there in the loose sands, and afford, as in africa, food for camels. the western group of the canaries presents a more elevated soil, is more woody, and is watered by a greater number of springs. though the whole archipelago contains several plants found also in portugal,* (* m. willdenouw and myself found, among the plants of the peak of teneriffe, the beautiful satyrium diphyllum (orchis cordata, willd.) which mr. link discovered in portugal. the canaries have, in common with the flora of the azores, not the dicksonia culcita, the only arborescent heath found at the thirty-ninth degree of latitude, but the asplenium palmatum, and the myrica faya. this last tree is met with in portugal, in a wild state. count hoffmansegg has seen very old trunks of it; but it was doubtful whether it was indigenous, or imported into that part of our continent. in reflecting on the migrations of plants, and on the geological possibility, that lands sunk in the ocean may have heretofore united portugal, the azores, the canaries, and the chain of atlas, we conceive, that the existence of the myrica faya in western europe is a phenomenon at least as striking as that of the pine of aleppo would be at the azores.), in spain, at the azores, and in the north-west of africa, yet a great number of species, and even some genera, are peculiar to teneriffe, to porto santo, and to madeira. such are the mocanera, the plocama, the bosea, the canarina, the drusa, and the pittosporum. a form which may be called northern, that of the cruciform plant (among the small number of cruciform species contained in the flora of teneriffe, we shall here mention cheiranthus longifolius, l'herit.; ch. fructescens, vent.; ch. scoparius, brouss.; erysimum bicorne, aiton; crambe strigosa, and c. laevigata, brouss.), is much rarer in the canaries than in spain and in greece. still farther to the south, in the equinoctial regions of both continents, where the mean temperature of the air rises above twenty-two degrees, the cruciform plants are scarcely ever to be seen. a question highly interesting to the history of the progressive marks of organization on the globe has been very warmly discussed in our own times, that of ascertaining whether the polymorphous plants are more common in the volcanic islands. the vegetation of teneriffe is unfavourable to the hypothesis that nature in new countries is but little subject to permanent forms. m. broussonnet, who resided so long at the canaries, asserts that the variable plants are not more common there than in the south of europe. may it not to be presumed, that the polymorphous species, which are so abundant in the isle of bourbon, are assignable to the nature of the soil and climate rather than to the newness of the vegetation? before we take leave of the old world to pass into the new, i must advert to a subject which is of general interest, because it belongs to the history of man, and to those fatal revolutions which have swept off whole tribes from the face of the earth. we inquire at the isle of cuba, at st. domingo, and in jamaica, where is the abode of the primitive inhabitants of those countries? we ask at teneriffe what is become of the guanches, whose mummies alone, buried in caverns, have escaped destruction? in the fifteenth century almost all mercantile nations, especially the spaniards and the portuguese, sought for slaves at the canary islands, as in later times they have been sought on the coast of guinea.* (* the spanish historians speak of expeditions made by the huguenots of rochelle to carry off guanche slaves. i have some doubt respecting these expeditions, which are said to have taken place subsequently to the year .) the christian religion, which in its origin was so highly favourable to the liberty of mankind, served afterwards as a pretext to the cupidity of europeans. every individual, made prisoner before he received the rite of baptism, became a slave. at that period no attempt had yet been made to prove that the blacks were an intermediate race between man and animals. the swarthy guanche and the african negro were simultaneously sold in the market of seville, without a question whether slavery should be the doom only of men with black skins and woolly hair. the archipelago of the canaries was divided into several small states hostile to each other, and in many instances the same island was subject to two independent princes. the trading nations, influenced by the hideous policy still exercised on the coast of africa, kept up intestine warfare. one guanche then became the property of another, who sold him to the europeans; several, who preferred death to slavery, killed themselves and their children. the population of the canaries had considerably suffered by the slave trade, by the depredations of pirates, and especially by a long period of carnage, when alonzo de lugo completed the conquest of the guanches. the surviving remnants of the race perished mostly in , in the terrible pestilence called the modorra, which was attributed to the quantity of dead bodies left exposed in the open air by the spaniards after the battle of la laguna. the nation of the guanches was extinct at the beginning of the seventeenth century; a few old men only were found at candelaria and guimar. it is, however, consoling to find that the whites have not always disdained to intermarry with the natives; but the canarians of the present day, whom the spaniards familiarly call islenos (islanders), have very powerful motives for denying this mixture. in a long series of generations time effaces the characteristic marks of a race; and as the descendants of the andalusians settled at teneriffe are themselves of dark complexion, we may conceive that intermarriages cannot have produced a perceptible change in the colour of the whites. it is very certain that no native of pure race exists in the whole island. it is true that a few canarian families boast of their relationship to the last shepherd-king of guimar, but these pretensions do not rest on very solid foundations, and are only renewed from time to time when some canarian of more dusky hue than his countrymen is prompted to solicit a commission in the service of the king of spain. a short time after the discovery of america, when spain was at the highest pinnacle of her glory, the gentle character of the guanches was the fashionable topic, as we in our times laud the arcadian innocence of the inhabitants of otaheite. in both these pictures the colouring is more vivid than true. when nations, wearied with mental enjoyments, behold nothing in the refinement of manners but the germ of depravity, they are pleased with the idea, that in some distant region, in the first dawn of civilization, infant society enjoys pure and perpetual felicity. to this sentiment tacitus owed a part of his success, when he sketched for the romans, subjects of the caesars, a picture of the manners of the inhabitants of germany. the same sentiment gives an ineffable charm to the narrative of those travellers who, at the close of the last century, visited the south sea islands. the inhabitants of those islands, too much vaunted (and previously anthropophagi), resemble, under more than one point of view, the guanches of teneriffe. both nations were under the yoke of feudal government. among the guanches, this institution, which facilitates and renders a state of warfare perpetual, was sanctioned by religion. the priests declared to the people: "the great spirit, achaman, created first the nobles, the achimenceys, to whom he distributed all the goats that exist on the face of the earth. after the nobles, achaman created the plebeians, achicaxnas. this younger race had the boldness to petition also for goats; but the supreme spirit answered, that this race was destined to serve the nobles, and that they had need of no property." this tradition was made, no doubt, to please the rich vassals of the shepherd-kings. the faycan, or high priest, also exercised the right of conferring nobility; and the law of the guanches expressed that every achimencey who degraded himself by milking a goat with his own hands, lost his claim to nobility. this law does not remind us of the simplicity of the homeric age. we are astonished to see the useful labours of agriculture, and of pastoral life, exposed to contempt at the very dawn of civilization. the guanches, famed for their tall stature, were the patagonians of the old world. historians exaggerated the muscular strength of the guanches, as, previous to the voyage of bougainville and cordoba, colossal proportions were attributed to the tribe that inhabited the southern extremity of america. i never saw guanche mummies but in the cabinets of europe. at the time i visited the canaries they were very scarce; a considerable number, however, might be found if miners were employed to open the sepulchral caverns which are cut in the rock on the eastern slope of the peak, between arico and guimar. these mummies are in a state of desiccation so singular, that whole bodies, with their integuments, frequently do not weigh above six or seven pounds; or a third less than the skeleton of an individual of the same size, recently stripped of the muscular flesh. the conformation of the skull has some slight resemblance to that of the white race of the ancient egyptians; and the incisive teeth of the guanches are blunted, like those of the mummies found on the banks of the nile. but this form of teeth is the result of art; and on examining more carefully the physiognomy of the ancient canarians, blumenbach and other able anatomists have recognized in the cheek bones and the lower jaw perceptible differences from the egyptian mummies. on opening those of the guanches, remains of aromatic plants are discovered, among which the chenopodium ambrosioides is constantly perceived: the bodies are often decorated with small laces, to which are hung little discs of baked earth, which appear to have served as numerical signs, and resemble the quippoes of the peruvians, the mexicans, and the chinese. the population of islands being in general less exposed than that of continents to the effect of migrations, we may presume that, in the time of the carthaginians and the greeks, the archipelago of the canaries was inhabited by the same race of men as were found by the norman and spanish conquerors. the only monument that can throw any light on the origin of the guanches is their language; but unhappily there are not above a hundred and fifty words extant, and several express the same object, according to the dialect of the different islanders. independently of these words, which have been carefully noted, there are still some valuable fragments existing in the names of a great number of hamlets, hills, and valleys. the guanches, like the biscayans, the hindoos, the peruvians, and all primitive nations, named places after the quality of the soil, the shape of the rocks, the caverns that gave them shelter, and the nature of the tree that overshadowed the springs.* (* it has been long imagined, that the language of the guanches had no analogy with the living tongues; but since the travels of hornemann, and the ingenious researches of marsden and venturi, have drawn the attention of the learned to the berbers, who, like the sarmatic tribes, occupy an immense extent of country in the north of africa, we find that several guanche words have common roots with words of the chilha and gebali dialects. we shall cite, for instance, the words: table of words. column : word. column : in guanche. column : in berberic. heaven : tigo : tigot. milk : aho : acho. barley : temasen : tomzeen. basket : carianas : carian. water : aenum : anan. i doubt whether this analogy is a proof of a common origin; but it is an indication of the ancient connexion between the guanches and berbers, a tribe of mountaineers, in which the ancient numidians, getuli, and garamanti are confounded, and who extend themselves from the eastern extremity of atlas by harutsh and fezzan, as far as the oasis of siwah and augela. the natives of the canary islands called themselves guanches, from guan, man; as the tonguese call themselves bye, and tongui, which have the same signification as guan. besides the nations who speak the berberic language are not all of the same race; and the description which scylax gives, in his periplus, of the inhabitants of cerne, a shepherd people of tall stature and long hair, reminds us of the features which characterize the canarian guanches.) the greater attention we direct to the study of languages in a philosophical point of view, the more we must observe that no one of them is entirely distinct. the language of the guanches would appear still less so, had we any data respecting its mechanism and grammatical construction; two elements more important than the form of words, and the identity of sounds. it is the same with certain idioms, as with those organized beings that seem to shrink from all classification in the series of natural families. their isolated state is merely apparent; for it ceases when, on embracing a greater number of objects, we come to discover the intermediate links. those learned enquirers who trace egyptians wherever there are mummies, hieroglyphics, or pyramids, will imagine perhaps that the race of typhon was united to the guanches by the berbers, real atlantes, to whom belong the tibboes and the tuarycks of the desert: but this hypothesis is supported by no analogy between the berberic and coptic languages, which are justly considered as remnants of the ancient egyptian. the people who have succeeded the guanches are descended from the spaniards, and in a more remote degree from the normans. though these two races have been exposed during three centuries past to the same climate, the latter is distinguished by the fairer complexion. the descendants of the normans inhabit the valley of teganana, between punta de naga and punta de hidalgo. the names of grandville and dampierre are still pretty common in this district. the canarians are a moral, sober, and religious people, of a less industrious character at home than in foreign countries. a roving and enterprising disposition leads these islanders, like the biscayans and catalonians, to the philippines, to the ladrone islands, to america, and wherever there are spanish settlements, from chile and la plata to new mexico. to them we are in a great measure indebted for the progress of agriculture in those colonies. the whole archipelago does not contain , inhabitants, and the islenos are perhaps more numerous in the new continent than in their own country. chapter . . passage from tenerife to south america. the island of tobago. arrival at cumana. we left the road of santa cruz on the th of june, and directed our course towards south america. we soon lost sight of the canary islands, the lofty mountains of which were covered with a reddish vapour. the peak alone appeared from time to time, as at intervals the wind dispersed the clouds that enveloped the piton. we felt, for the first time, how strong are the impressions left on the mind from the aspect of those countries situated on the limits of the torrid zone, where nature appears at once so rich, so various, and so majestic. our stay at teneriffe had been very short, and yet we withdrew from the island as if it had long been our home. our passage from santa cruz to cumana, the most eastern part of the new continent, was very fine. we cut the tropic of cancer on the th; and though the pizarro was not a very fast sailer, we made, in twenty days, the nine hundred leagues, which separate the coast of africa from that of the new continent. we passed fifty leagues west of cape bojador, cape blanco, and the cape verd islands. a few land birds, which had been driven to sea by the impetuosity of the wind followed us for several days. the latitude diminished rapidly, from the parallel of madeira to the tropic. when we reached the zone where the trade-winds are constant, we crossed the ocean from east to west, on a calm sea, which the spanish sailors call the ladies' gulf, el golfo de las damas. in proportion as we advanced towards the west, we found the trade-winds fix to eastward. these winds, the most generally adopted theory of which is explained in a celebrated treatise of halley,* are a phenomenon much more complicated than most persons admit. (* the existence of an upper current of air, which blows constantly from the equator to the poles, and of a lower current, which blows from the poles to the equator, had already been admitted, as m. arago has shown, by hooke. the ideas of the celebrated english naturalist are developed in a discourse on earthquakes published in . "i think (adds he) that several phenomena, which are presented by the atmosphere and the ocean, especially the winds, may be explained by the polar currents."--hooke's posthumous works page .) in the atlantic ocean, the longitude, as well as the declination of the sun, influences the direction and limits of the trade-winds. in the direction of the new continent, in both hemispheres, these limits extend beyond the tropics eight or nine degrees; while in the vicinity of africa, the variable winds prevail far beyond the parallel of or degrees. it is to be regretted, on account of the progress of meteorology and navigation, that the changes of the currents of the equinoctial atmosphere in the pacific are much less known than the variation of these same currents in a sea that is narrower, and influenced by the proximity of the coasts of guinea and brazil. the difference with which the strata of air flow back from the two poles towards the equator cannot be the same in every degree of longitude, that is to say, on points of the globe where the continents are of very different breadths, and where they stretch away more or less towards the poles. it is known, that in the passage from santa cruz to cumana, as in that from acapulco to the philippine islands, seamen are scarcely ever under the necessity of working their sails. we pass those latitudes as if we were descending a river, and we might deem it no hazardous undertaking if we made the voyage in an open boat. farther west, on the coast of santa martha and in the gulf of mexico, the trade-wind blows impetuously, and renders the sea very stormy.* (* the spanish sailors call the rough trade-winds at carthagena in the west indies los brisotes de santa martha; and in the gulf of mexico, las brizas pardas. these latter winds are accompanied with a grey and cloudy sky.) the wind fell gradually the farther we receded from the african coast: it was sometimes smooth water for several hours, and these short calms were regularly interrupted by electrical phenomena. black thick clouds, marked by strong outlines, rose on the east, and it seemed as if a squall would have forced us to hand our topsails; but the breeze freshened anew, there fell a few large drops of rain, and the storm dispersed without our hearing any thunder. meanwhile it was curious to observe the effect of several black, isolated, and very low clouds, which passed the zenith. we felt the force of the wind augment or diminish progressively, according as small bodies of vesicular vapour approached or receded, while the electrometers, furnished with a long metallic rod and lighted match, showed no change of electric tension in the lower strata of the air. it is by help of these squalls, which alternate with dead calms, that the passage from the canary islands to the antilles, or southern coast of america, is made in the months of june and july. some spanish navigators have lately proposed going to the west indies and the coasts of terra firma by a course different from that which was taken by columbus. they advise, instead of steering directly to the south in search of the trade-winds, to change both latitude and longitude, in a diagonal line from cape st. vincent to america. this method, which shortens the way, cutting the tropic nearly twenty degrees west of the point where it is commonly cut by pilots, was several times successfully adopted by admiral gravina. that able commander, who fell at the battle of trafalgar, arrived in at st. domingo, by the oblique passage, several days before the french fleet, though orders of the court of madrid would have forced him to enter ferrol with his squadron, and stop there some time. this new system of navigation shortens the passage from cadiz to cumana one-twentieth; but as the tropic is attained only at the longitude of forty degrees, the chance of meeting with contrary winds, which blow sometimes from the south, and at other times from the south-west, is more unfavourable. in the old system, the disadvantage of making a longer passage is compensated by the certainty of catching the trade-winds in a shorter space of time, and keeping them the greater part of the passage. at the time of my abode in the spanish colonies, i witnessed the arrival of several merchant-ships, which from the fear of privateers had chosen the oblique course, and had had a very short passage. nothing can equal the beauty and mildness of the climate of the equinoctial region on the ocean. while the trade wind blew strongly, the thermometer kept at or degrees in the day, and at or . degrees during the night. the charm of the lovely climates bordering on the equator, can be fully enjoyed only by those who have undertaken the voyage from acapulco or the coasts of chile to europe in a very rough season. what a contrast between the tempestuous seas of the northern latitudes and the regions where the tranquillity of nature is never disturbed! if the return from mexico or south america to the coasts of spain were as expeditious and as agreeable as the passage from the old to the new continent, the number of europeans settled in the colonies would be much less considerable than it is at present. to the sea which surrounds the azores and the bermuda islands, and which is traversed in returning to europe by the high latitudes, the spaniards have given the singular name of golfo de las yeguas (the mares' gulf). colonists who are not accustomed to the sea, and who have led solitary lives in the forests of guiana, the savannahs of the caracas, or the cordilleras of peru, dread the vicinity of the bermudas more than the inhabitants of lima fear at present the passage round cape horn. to the north of the cape verd islands we met with great masses of floating seaweeds. they were the tropic grape, (fucus natans), which grows on submarine rocks, only from the equator to the fortieth degree of north and south latitude. these weeds seem to indicate the existence of currents in this place, as well as to south-west of the banks of newfoundland. we must not confound the latitudes abounding in scattered weeds with those banks of marine plants, which columbus compares to extensive meadows, the sight of which dismayed the crew of the santa maria in the forty-second degree of longitude. i am convinced, from the comparison of a great number of journals, that in the basin of the northern atlantic there exist two banks of weeds very different from each other. the most extensive is a little west of the meridian of fayal, one of the azores, between the twenty-fifth and thirty-sixth degrees of latitude.* (* it would appear that phoenician vessels came "in thirty days' sail, with an easterly wind," to the weedy sea, which the portuguese and spaniards call mar de zargasso. i have shown, in another place (views of nature bohn's edition page ), that the passage of aristotle, de mirabil. (ed. duval page ), can scarcely be applied to the coasts of africa, like an analogous passage of the periplus of scylax. supposing that this sea, full of weeds, which impeded the course of the phoenician vessels, was the mar de zargasso, we need not admit that the ancients navigated the atlantic beyond thirty degrees of west longitude from the meridian of paris.) the temperature of the atlantic in those latitudes is from sixteen to twenty degrees, and the north winds, which sometimes rage there very tempestuously, drive floating isles of seaweed into the low latitudes as far as the parallels of twenty-four and even twenty degrees. vessels returning to europe, either from monte video or the cape of good hope, cross these banks of fucus, which the spanish pilots consider as at an equal distance from the antilles and canaries; and they serve the less instructed mariner to rectify his longitude. the second bank of fucus is but little known; it occupies a much smaller space, in the twenty-second and twenty-sixth degrees of latitude, eighty leagues west of the meridian of the bahama islands. it is found on the passage from the caiques to the bermudas. though a species of seaweed* (* the baudreux of the falkland islands; fucus giganteus, forster; laminaria pyrifera, lamour.) has been seen with stems eight hundred feet long, the growth of these marine cryptogamia being extremely rapid, it is nevertheless certain, that in the latitudes we have just described, the fuci, far from being fixed to the bottom, float in separate masses on the surface of the water. in this state, the vegetation can scarcely last longer than it would in the branch of a tree torn from its trunk; and in order to explain how moving masses are found for ages in the same position, we must admit that they owe their origin to submarine rocks, which, lying at forty or sixty fathoms' depth, continually supply what has been carried away by the equinoctial currents. this current bears the tropic grape into the high latitudes, toward the coasts of norway and france; and it is not the gulf-stream, as some mariners think, which accumulates the fucus to the south of the azores. the causes that unroot these weeds at depths where it is generally thought the sea is but slightly agitated, are not sufficiently known. we learn only, from the observations of m. lamouroux, that if the fucus adhere to the rocks with the greatest firmness before its fructification, it separates with great facility after that period, or during the season which suspends its vegetation like that of the terrestrial plants. the fish and mollusca which gnaw the stems of the seaweeds no doubt contribute also to detach them from their roots. from the twenty-second degree of latitude, we found the surface of the sea covered with flying-fish,* (* exocoetus volitans.) which threw themselves up into the air, twelve, fifteen, or eighteen feet, and fell down on the deck. i do not hesitate to speak on a subject of which voyagers discourse as frequently as of dolphins, sharks, sea-sickness, and the phosphorescence of the ocean. none of these topics can fail to afford interesting observations to naturalists, provided they make them their particular study. nature is an inexhaustible source of investigation, and in proportion as the domain of science is extended, she presents herself to those who know how to interrogate her, under forms which they have never yet examined. i have named the flying-fish, in order to direct the attention of naturalists to the enormous size of their natatory bladder, which, in an animal of . inches, is . inches long, . of an inch broad, and contains three cubic inches and a half of air. as this bladder occupies more than half the size of the fish, it is probable that it contributes to its lightness. we may assert that this reservoir of air is more fitted for flying than swimming; for the experiments made by m. provenzal and myself have proved, that, even in the species which are provided with this organ, it is not indispensably necessary for the ascending movement to the surface of the water. in a young flying-fish, . inches long, each of the pectoral fins, which serve as wings, presented a surface to the air of / square inches. we observed, that the nine branches of nerves, which go to the twelve rays of these fins, are almost three times the size of the nerves that belong to the ventral fins. when the former of these nerves are excited by galvanic electricity, the rays which support the membrane of the pectoral fin extend with five times the force with which the other fins move when galvanised by the same metals. thus, the fish is capable of throwing itself horizontally the distance of twenty feet before retouching the water with the extremity of its fins. this motion has been aptly compared to that of a flat stone, which, thrown horizontally, bounds one or two feet above the water. notwithstanding the extreme rapidity of this motion, it is certain, that the animal beats the air during the leap; that is, it alternately extends and closes its pectoral fins. the same motion has been observed in the flying scorpion of the rivers of japan: they also contain a large air-bladder, with which the great part of the scorpions that have not the faculty of flying are unprovided. the flying-fish, like almost all animals which have gills, enjoy the power of equal respiration for a long time, both in water and in air, by the same organs; that is, by extracting the oxygen from the atmosphere as well as from the water in which it is dissolved. they pass a great part of their life in the air; but if they escape from the sea to avoid the voracity of the dorado, they meet in the air the frigate-bird, the albatross, and others, which seize them in their flight. thus, on the banks of the orinoco, herds of the cabiai, which rush from the water to escape the crocodile, become the prey of the jaguar, which awaits their arrival. i doubt, however, whether the flying-fish spring out of the water merely to escape the pursuit of their enemies. like swallows, they move by thousands in a right line, and in a direction constantly opposite to that of the waves. in our own climates, on the brink of a river, illumined by the rays of the sun, we often see solitary fish fearlessly bound above the surface as if they felt pleasure in breathing the air. why should not these gambols be more frequent with the flying-fish, which from the strength of their pectoral fins, and the smallness of their specific gravity, can so easily support themselves in the air? i invite naturalists to examine whether other flying-fish, for instance the exocoetus exiliens, the trigla volitans, amid the t. hirundo, have as capacious an air-bladder as the flying-fish of the tropics. this last follows the heated waters of the gulf-stream when they flow northward. the cabin-boys amuse themselves with cutting off a part of the pectoral fins, and assert, that these wings grow again; which seems to me not unlikely, from facts observed in other families of fishes. at the time i left paris, experiments made at jamaica by dr. brodbelt, on the air contained in the natatory bladder of the sword-fish, had led some naturalists to think, that within the tropics, in sea-fish, that organ must be filled with pure oxygen gas. full of this idea, i was surprised at finding in the air-bladder of the flying-fish only . of oxygen to . of azote and . of carbonic acid. the proportion of this last gas, measured by the absorption of lime-water in graduated tubes, appeared more uniform than that of the oxygen, of which some individuals yielded almost double the quantity. from the curious phenomena observed by mm. biot, configliachi, and delaroche, we might suppose, that the swordfish dissected by dr. brodbelt had inhabited the lower strata of the ocean, where some fish* have as much as . of oxygen in the air-bladder. (* trigla cucullus.) on the rd and th of july, we crossed that part of the atlantic where the charts indicate the bank of the maal-stroom; and towards night we altered our course to avoid the danger, the existence of which is, however, as doubtful as that of the isles fonseco and st. anne. it would have been perhaps as prudent to have continued our course. the old charts are filled with rocks, some of which really exist, though most of them are merely the offspring of those optical illusions which are more frequent at sea than in inland places. as we approached the supposed maal-stroom, we observed no other motion in the waters than the effect of a current which bore to the north-west, and which hindered us from diminishing our latitude as much as we wished. the force of this current augments as we approach the new continent; it is modified by the configuration of the coasts of brazil and guiana, and not by the waters of the orinoco and the amazon, as some have supposed. from the time we entered the torrid zone, we were never weary of admiring, at night, the beauty of the southern sky, which, as we advanced to the south, opened new constellations to our view. we feel an indescribable sensation when, on approaching the equator, and particularly on passing from one hemisphere to the other, we see those stars, which we have contemplated from our infancy, progressively sink, and finally disappear. nothing awakens in the traveller a livelier remembrance of the immense distance by which he is separated from his country, than the aspect of an unknown firmament. the grouping of the stars of the first magnitude, some scattered nebulae, rivalling in splendour the milky way, and tracts of space remarkable for their extreme blackness, give a peculiar physiognomy to the southern sky. this sight fills with admiration even those who, uninstructed in the several branches of physical science, feel the same emotion of delight in the contemplation of the heavenly vault, as in the view of a beautiful landscape, or a majestic site. a traveller needs not to be a botanist, to recognize the torrid zone by the mere aspect of its vegetation. without having acquired any notions of astronomy, without any acquaintance with the celestial charts of flamsteed and de la caille, he feels he is not in europe, when he sees the immense constellation of the ship, or the phosphorescent clouds of magellan, arise on the horizon. the heavens and the earth,--everything in the equinoctial regions, presents an exotic character. the lower regions of the air were loaded with vapours for some days. we saw distinctly for the first time the southern cross only on the night of the th of july, in the sixteenth degree of latitude. it was strongly inclined, and appeared from time to time between the clouds, the centre of which, furrowed by uncondensed lightnings, reflected a silvery light. if a traveller may be permitted to speak of his personal emotions, i shall add, that on that night i experienced the realization of one of the dreams of my early youth. when we begin to fix our eyes on geographical maps, and to read the narratives of navigators, we feel for certain countries and climates a sort of predilection, which we know not how to account for at a more advanced period of life. these impressions, however, exercise a considerable influence over our determinations; and from a sort of instinct we endeavour to connect ourselves with objects on which the mind has long been fixed as by a secret charm. at a period when i studied the heavens, not with the intention of devoting myself to astronomy, but only to acquire a knowledge of the stars, i was disturbed by a feeling unknown to those who are devoted to sedentary life. it was painful to me to renounce the hope of beholding the beautiful constellations near the south pole. impatient to rove in the equinoctial regions, i could not raise my eyes to the starry firmament without thinking of the southern cross, and recalling the sublime passage of dante, which the most celebrated commentators have applied to that constellation:-- io mi volsi a man' destra e posi mente all' altro polo, e vidi quattro stelle non viste mai fuorch' alla prima gente. goder parea lo ciel di lor fiammelle; o settentrional vedovo sito poiche privato sei di mirar quelle! the pleasure we felt on discovering the southern cross was warmly shared by those of the crew who had visited the colonies. in the solitude of the seas we hail a star as a friend, from whom we have long been separated. the portuguese and the spaniards are peculiarly susceptible of this feeling; a religious sentiment attaches them to a constellation, the form of which recalls the sign of the faith planted by their ancestors in the deserts of the new world. the two great stars which mark the summit and the foot of the cross having nearly the same right ascension, it follows that the constellation is almost perpendicular at the moment when it passes the meridian. this circumstance is known to the people of every nation situated beyond the tropics, or in the southern hemisphere. it has been observed at what hour of the night, in different seasons, the cross is erect or inclined. it is a timepiece which advances very regularly nearly four minutes a-day, and no other group of stars affords to the naked eye an observation of time so easily made. how often have we heard our guides exclaim in the savannahs of venezuela, or in the desert extending from lima to truxillo, "midnight is past, the cross begins to bend!" how often those words reminded us of that affecting scene, where paul and virginia, seated near the source of the river of lataniers, conversed together for the last time, and where the old man, at the sight of the southern cross, warns them that it is time to separate. the last days of our passage were not so felicitous as the mildness of the climate and the calmness of the ocean had led us to hope. the dangers of the sea did not disturb us, but the germs of a malignant fever became manifest on board our vessel as we drew near the antilles. between decks the ship was excessively hot, and very much crowded. from the time we passed the tropic, the thermometer was at thirty-four or thirty-six degrees. two sailors, several passengers, and, what is remarkable enough, two negroes from the coast of guinea, and a mulatto child, were attacked with a disorder which appeared to be epidemic. the symptoms were not equally alarming in all the cases; nevertheless, several persons, and especially the most robust, fell into delirium after the second day. no fumigation was made. a gallician surgeon, ignorant and phlegmatic, ordered bleedings, because he attributed the fever to what he called heat and corruption of the blood. there was not an ounce of bark on board; for we had emitted to take any with us, under the impression that this salutary production of peru could not fail to be found on board a spanish vessel. on the th of july, a sailor, who was near expiring, recovered his health from a circumstance worthy of being mentioned. his hammock was so hung, that there was not ten inches between his face and the deck. it was impossible to administer the sacrament in this situation; for, agreeably to the custom on board spanish vessels, the viaticum must be carried by the light of tapers, and followed by the whole crew. the patient was removed into an airy place near the hatchway, where a small square berth had been formed with sailcloth. here he was to remain till he died, which was an event expected every moment; but passing from an atmosphere heated, stagnant, and filled with miasma, into fresher and purer air, which was renewed every instant, he gradually revived from his lethargic state. his recovery dated from the day when he quitted the middle deck; and as it often happens in medicine that the same facts are cited in support of systems diametrically opposite, this recovery confirmed our doctor in his idea of the inflammation of the blood, and the necessity of bleeding, evacuating, and all the asthenic remedies. we soon felt the fatal effects of this treatment. for several days the pilot's reckoning differed degree minutes in longitude from that of my time. this difference was owing less to the general current, which i have called the current of rotation, than to that particular movement, which, drawing the waters toward the north-west, from the coast of brazil to the antilles, shortens the passage from cayenne to guadaloupe.* (* in the atlantic ocean there is a space where the water is constantly milky, though the sea is very deep. this curious phenomenon exists in the parallel of the island of dominica, very near the th degree of longitude. may there not be in this place some sunken volcanic islet, more easterly still than barbadoes?) on the th of july, i thought i might foretell our seeing land next day before sunrise. we were then, according to my observations, in latitude degrees minutes, and west longitude degrees minutes. a few series of lunar distances confirmed the chronometrical result; but we were surer of the position of the vessel, than of that of the land to which we were directing our course, and which was so differently marked in the french, spanish, and english charts. the longitudes deduced from the accurate observations of messrs. churruca, fidalgo, and noguera, were not then published. the pilots trusted more to the log than the timekeeper; they smiled at the prediction of so speedily making land, and thought themselves two or three days' sail from the coast. it was therefore with great pleasure, that on the th, about six in the morning, i learned that very high land was seen from the mast-head, though not clearly, as it was surrounded with a thick fog. the wind blew hard, and the sea was very rough. large drops of rain fell at intervals, and every indication menaced tempestuous weather. the captain of the pizarro intended to pass through the channel which separates the islands of tobago and trinidad; and knowing that our sloop was very slow in tacking, he was afraid of falling to leeward towards the south, and approaching the boca del drago. we were in fact surer of our longitude than of our latitude, having had no observation at noon since the th. double altitudes which i took in the morning, after douwes's method, placed us in degrees minutes seconds, consequently minutes north of our reckoning. though the result clearly proved that the high land on the horizon was not trinidad, but tobago, yet the captain continued to steer north-north-west, in search of this latter island. an observation of the meridian altitude of the sun fully confirmed the latitude obtained by douwes's method. no more doubt remained as to the position of the vessel, with respect to the island, and we resolved to double cape north (tobago) to pass between that island and grenada, and steer towards a port in margareta. the island of tobago presents a very picturesque aspect. it is merely a heap of rocks carefully cultivated. the dazzling whiteness of the stone forms an agreeable contrast to the verdure of some scattered tufts of trees. cylindric and very lofty cactuses crown the top of the mountains, and give a peculiar physiognomy to this tropical landscape. the sight of the trees alone is sufficient to remind the navigator that he has reached an american coast; for these cactuses are as exclusively peculiar to the new world, as the heaths are to the old. we crossed the shoal which joins tobago to the island of grenada. the colour of the sea presented no visible change; but the centigrade thermometer, plunged into the water to the depth of some inches, rose only to degrees; while farther at sea eastward on the same parallel, and equally near the surface, it kept at . degrees. notwithstanding the currents, the cooling of the water indicated the existence of the shoal, which is noted in only a very few charts. the wind slackened after sunset, and the clouds disappeared as the moon reached the zenith. the number of falling stars was very considerable on this and the following nights; they appeared less frequent towards the north than the south over terra firma, which we began to coast. this position seems to prove the influence of local causes on meteors, the nature of which is not yet sufficiently known to us. on the th at sunrise, we were in sight of the boca del drago. we distinguished chacachacarreo, the most westerly of the islands situated between cape paria and the north-west cape of trinidad. when we were five leagues distant from the coast, we felt, near punta de la boca, the effect of a particular current which carried the ship southward. the motion of the waters which flow through the boca del draco, and the action of the tides, occasion an eddy. we cast the lead, and found from thirty-six to forty-three fathoms on a bottom of very fine green clay. according to the rules established by dampier, we ought not to have expected so little depth near a coast formed by very high and perpendicular mountains. we continued to heave the lead till we reached cabo de tres puntas* (* cape three points, the name given to it by columbus.) and we every where found shallow water, apparently indicating the prolongation of the ancient coast. in these latitudes the temperature of the sea was from twenty-three to twenty-four degrees, consequently from . to two degrees lower than in the open ocean, beyond the edge of the bank. the cabo de tres puntas is, according to my observations, in degrees minutes seconds longitude. it seemed to us the more elevated, as the clouds concealed the view of its indented top. the aspect of the mountains of paria, their colour, and especially their generally rounded forms, made us suspect that the coast was granitic; but we afterwards recognized how delusive, even to those who have passed their lives in scaling mountains, are impressions respecting the nature of rocks seen at a distance. a dead calm, which lasted several hours, permitted us to determine with exactness the intensity of the magnetic forces opposite the cabo de tres puntas. this intensity was greater than in the open sea, to the east of the island of tobago, in the ratio of from to . during the calm the current drew us on rapidly to the west. its velocity was three miles an hour, and it increased as we approached the meridian of testigos, a heap of rocks which rises up amidst the waters. at the setting of the moon, the sky was covered with clouds, the wind freshened anew, and the rain descended in one of those torrents peculiar to the torrid zone. the malady which had broken out on board the pizarro had made rapid progress, from the time when we approached the coasts of terra firma; but having then almost reached the end of our voyage we flattered ourselves that all who were sick would be restored to health, as soon as we could land them at the island of st. margareta, or the port of cumana, places remarkable for their great salubrity. this hope was unfortunately not realised. the youngest of the passengers attacked with the malignant fever fell a victim to the disease. he was an asturian, nineteen years of age, the only son of a poor widow. several circumstances rendered the death of this young man affecting. his countenance bore the expression of sensibility and great mildness of disposition. he had embarked against his own inclination; and his mother, whom he had hoped to assist by the produce of his efforts, had made a sacrifice of her affection in the hope of securing the fortune of her son, by sending him to the colonies to a rich relation, who resided at the island of cuba. the unfortunate young man expired on the third day of his illness, having fallen from the beginning into a lethargic state interrupted only by fits of delirium. the yellow fever, or black vomit, at vera cruz, scarcely carries off the sick with so alarming a rapidity. another asturian, still younger, did not leave for one moment the bed of his dying friend; and, what is very remarkable, did not contract the disorder. we were assembled on the deck, absorbed in melancholy reflections. it was no longer doubtful, that the fever which raged on board had assumed within the last few days a fatal aspect. our eyes were fixed on a hilly and desert coast on which the moon, from time to time, shed her light athwart the clouds. the sea, gently agitated, emitted a feeble phosphoric light. nothing was heard but the monotonous cry of a few large sea-birds, flying towards the shore. a profound calm reigned over these solitary regions, but this calm of nature was in discordance with the painful feelings by which we were oppressed. about eight o'clock the dead man's knell was slowly tolled. at this lugubrious sound, the sailors suspended their labours, and threw themselves on their knees to offer a momentary prayer: an affecting ceremony, which brought to our remembrance those times when the primitive christians all considered themselves as members of the same family. all were united in one common sorrow for a misfortune which was felt to be common to all. the corpse of the young asturian was brought upon deck during the night, but the priest entreated that it might not be committed to the waves till after sunrise, that the last rites might be performed, according to the usage of the romish church. there was not an individual on board, who did not deplore the death of this young man, whom we had beheld, but a few days before, full of cheerfulness and health. those among the passengers who had not yet felt symptoms of the disease, resolved to leave the vessel at the first place where she might touch, and await the arrival of another packet, to pursue their course to the island of cuba and to mexico. they considered the between-decks of the ship as infected; and though it was by no means clear to me that the fever was contagious, i thought it most prudent to land at cumana. i wished not to visit new spain, till i had made some sojourn on the coasts of venezuela and paria; a few of the productions of which had been examined by the unfortunate loefling. we were anxious to behold in their native site, the beautiful plants which bose and bredemeyer had collected during their journey to the continent, and which adorn the conservatories of schoenbrunn and vienna. it would have been painful to have touched at cumana, or at guayra, without visiting the interior of a country so little frequented by naturalists. the resolution we formed during the night of the th of july, had a happy influence on the direction of our travels; for instead of a few weeks, we remained a whole year in this part of the continent. had not the fever broken out on board the pizarro, we should never have reached the orinoco, the cassiquiare, or even the limits of the portuguese possessions on the rio negro. to this direction given to our travels we were perhaps also indebted for the good health we enjoyed during so long an abode in the equinoctial regions. it is well known, that europeans, during the first months after their arrival under the scorching sky of the tropics, are exposed to the greatest dangers. they consider themselves to be safe, when they have passed the rainy season in the west india islands, at vera cruz, or at carthagena. this opinion is very general, although there are examples of persons, who, having escaped a first attack of the yellow fever, have fallen victims to the same disease in one of the following years. the facility of becoming acclimated, seems to be in the inverse ratio of the difference that exists between the mean temperature of the torrid zone, and that of the native country of the traveller, or colonist, who changes his climate; because the irritability of the organs, and their vital action, are powerfully modified by the influence of the atmospheric heat. a prussian, a pole, or a swede, is more exposed on his arrival at the islands or on the continent, than a spaniard, an italian, or even an inhabitant of the south of france. with respect to the people of the north, the difference of the mean temperature is from nineteen to twenty-one degrees, while to the people of southern countries it is only from nine to ten. we were fortunate enough to pass safely through the interval during which a european recently landed runs the greatest danger, in the extremely hot, but very dry climate of cumana, a city celebrated for its salubrity. on the morning of the th, when nearly on a line with the hill of st. joseph, we were surrounded by a great quantity of floating seaweed. its stems had those extraordinary appendages in the form of little cups and feathers, which don hippolyto ruiz remarked on his return from the expedition to chile, and which he described in a separate memoir as the generative organs of the fucus natans. a fortunate accident allowed us the means of verifying a fact which had been but once observed by naturalists. the bundles of fucus collected by m. bonpland were completely identical with the specimens given us by the learned authors of the flora of peru. on examining both with the microscope, we found that the supposed parts of fructification, the stamina and pistils, belong to a new genus, of the family of the ceratophytae. the coast of paria stretches to the west, forming a wall of rocks of no great height, with rounded tops and a waving outline. we were long without perceiving the bold coasts of the island of margareta, where we were to stop for the purpose of ascertaining whether we could touch at guayra. we had learned, by altitudes of the sun, taken under very favourable circumstances, how incorrect at that period were the most highly-esteemed marine charts. on the morning of the th, when the time-keeper placed us in degrees minute seconds longitude, we were not yet in the meridian of margareta island; though according to the reduced chart of the atlantic ocean, we ought to have passed the very lofty western cape of this island, which is laid down in longitude degrees minutes. the inaccuracy with which the coasts were delineated previously to the labours of fidalgo, noguera, and tiscar, and i may venture to add, before the astronomical observations i made at cumana, might have become dangerous to navigators, were not the sea uniformly calm in those regions. the errors in latitude were still greater than those in longitude, for the coasts of new andalusia stretch to the westward of cape three points (or tres puntas) fifteen or twenty miles more to the north, than appears in the charts published before the year . about eleven in the morning we perceived a very low islet, covered with a few sandy downs, and on which we discovered with our glasses no trace of habitation or culture. cylindrical cactuses rose here and there in the form of candelabra. the soil, almost destitute of vegetation, seemed to have a waving motion, in consequence of the extraordinary refraction which the rays of the sun undergo in traversing the strata of air in contact with plains strongly heated. under every zone, deserts and sandy shores appear like an agitated sea, from the effect of mirage. the coasts, seen at a distance, are like clouds, in which each observer meets the form of the objects that occupy his imagination. our bearings and our chronometer being at variance with the charts which we had to consult, we were lost in vain conjectures. some took mounds of sand for indian huts, and pointed out the place where they alleged the fort of pampatar was situated; others saw herds of goats, which are so common in the dry valley of st. john; or descried the lofty mountains of macanao, which seemed to them partly hidden by the clouds. the captain resolved to send a pilot on shore, and the men were preparing to get out the long-boat when we perceived two canoes sailing along the coast. we fired a gun as a signal for them, and though we had hoisted spanish colours, they drew near with distrust. these canoes, like all those in use among the natives, were constructed of the single trunk of a tree. in each canoe there were eighteen guayqueria indians, naked to the waist, and of very tall stature. they had the appearance of great muscular strength, and the colour of their skin was something between brown and copper-colour. seen at a distance, standing motionless, and projected on the horizon, they might have been taken for statues of bronze. we were the more struck with their appearance, as it did not correspond with the accounts given by some travellers respecting the characteristic features and extreme feebleness of the natives. we afterwards learned, without passing the limits of the province of cumana, the great contrast existing between the physiognomy of the guayquerias and that of the chaymas and the caribs. when we were near enough to hail them in spanish, the indians threw aside their mistrust, and came straight on board. they informed us that the low islet near which we were at anchor was coche, which had never been inhabited; and that spanish vessels coming from europe were accustomed to sail farther north, between this island and that of margareta, to take a coasting pilot at the port of pampatar. our inexperience had led us into the channel to the south of coche; and as at that period the english cruisers frequented this passage, the indians had at first taken us for an enemy's ship. the southern passage is, in fact, highly advantageous for vessels going to cumana and barcelona. the water is less deep than in the northern passage, which is much narrower; but there is no risk of touching the ground, if vessels keep very close to the island of lobos and the moros del tunal. the channel between coche and margareta is narrowed by the shoals off the north-west cape of coche, and by the bank that surrounds la punta de los mangles. the guayquerias belong to that tribe of civilized indians who inhabit the coasts of margareta and the suburbs of the city of cumana. next to the caribs of spanish guiana they are the finest race of men in terra firma. they enjoy several privileges, because from the earliest times of the conquest they remained faithful friends to the castilians. the king of spain styles them in his public acts, "his dear, noble, and loyal guayquerias." the indians of the two canoes we had met had left the port of cumana during the night. they were going in search of timber to the forests of cedar (cedrela odorata, linn.), which extend from cape san jose to beyond the mouth of rio carupano. they gave us some fresh cocoa-nuts, and very beautifully coloured fish of the chaetodon genus. what riches to our eyes were contained in the canoes of these poor indians! broad spreading leaves of vijao* (* heliconia bihai.) covered bunches of plantains. the scaly cuirass of an armadillo (dasypus), the fruit of the calabash tree (crescentia cujete), used as a cup by the natives, productions common in the cabinets of europe, had a peculiar charm for us, because they reminded us that, having reached the torrid zone, we had attained the end to which our wishes had been so long directed. the master of one of the canoes offered to remain on board the pizarro as coasting pilot (practico). he was a guayqueria of an excellent disposition, sagacious in his observations, and he had been led by intelligent curiosity to notice the productions of the sea as well as the plants of the country. by a fortunate chance, the first indian we met on our arrival was the man whose acquaintance became the most useful to us in the course of our researches. i feel a pleasure in recording in this itinerary the name of carlos del pino, who, during the space of sixteen months, attended us in our course along the coasts, and into the inland country. the captain of the corvette weighed anchor towards evening. before we left the shoal or placer of coche, i ascertained the longitude of the east cape of the island, which i found to be degrees minutes seconds. as we steered westward, we soon came in sight of the little island of cubagua, now entirely deserted, but formerly celebrated for its fishery of pearls. there the spaniards, immediately after the voyages of columbus and ojeda, founded, under the name of new cadiz, a town, of which there now remains no vestige. at the beginning of the sixteenth century the pearls of cubagua were known at seville, at toledo, and at the great fairs of augsburg and bruges. new cadiz having no water, that of the rio manzanares was conveyed thither from the neighbouring coast, though for some reason, i know not what, it was thought to be the cause of diseases of the eyes. the writers of that period all speak of the riches of the first planters, and the luxury they displayed. at present, downs of shifting sand cover this uninhabited land, and the name of cubagua is scarcely found in our charts. having reached these latitudes, we saw the high mountains of cape macanao, on the western side of the island of margareta, which rose majestically on the horizon. if we might judge from the angles of altitude of the tops, taken at eighteen miles' distance, they appeared to be about or toises high. according to berthoud's time-keeper, the longitude of cape macanao is degrees minutes seconds. i speak of the rocks at the extremity of the cape, and not that strip of very low land which stretches to the west, and loses itself in a shoal. the position of macanao and that which i have assigned to the east point of the island of coche, differ only four seconds in time, from the results obtained by m. fidalgo. there being little wind, the captain preferred standing off and on till daybreak. we passed a part of the night on deck. the guayqueria pilot conversed with us respecting the animals and plants of his country. we learned with great satisfaction that there was, a few leagues from the coast, a mountainous region inhabited by the spaniards, in which the cold was sensibly felt; and that in the plains there were two species of crocodiles, very different from each other, besides, boas, electric eels, and several kinds of tigers. though the words bava, cachicamo, and temblador, were entirely unknown to us, we easily guessed, from the pilot's simple description of their manners and forms, the species which the creoles distinguished by these denominations. chapter . . first abode at cumana. banks of the manzanares. on the th of july, , at break of day, we beheld a verdant coast, of picturesque aspect. the mountains of new andalusia, half-veiled by mists, bounded the horizon to the south. the city of cumana and its castle appeared between groups of cocoa-trees. we anchored in the port about nine in the morning, forty-one days after our departure from corunna; the sick dragged themselves on deck to enjoy the sight of a land which was to put an end to their sufferings. our eyes were fixed on the groups of cocoa-trees which border the river: their trunks, more than sixty feet high, towered over every object in the landscape. the plain was covered with the tufts of cassia, caper, and those arborescent mimosas, which, like the pine of italy, spread their branches in the form of an umbrella. the pinnated leaves of the palms were conspicuous on the azure sky, the clearness of which was unsullied by any trace of vapour. the sun was ascending rapidly toward the zenith. a dazzling light was spread through the air, along the whitish hills strewed with cylindric cactuses, and over a sea ever calm, the shores of which were peopled with alcatras,* (* a brown pelican, of the size of a swan. (pelicanus fuscus, linn.)) egrets, and flamingoes. the splendour of the day, the vivid colouring of the vegetable world, the forms of the plants, the varied plumage of the birds, everything was stamped with the grand character of nature in the equinoctial regions. the city of cumana, the capital of new andalusia, is a mile distant from the embarcadero, or the battery of the boca, where we landed, after having passed the bar of the manzanares. we had to cross a vast plain, called el salado, which divides the suburb of the guayquerias from the sea-coast. the excessive heat of the atmosphere was augmented by the reverberation of the soil, partly destitute of vegetation. the centigrade thermometer, plunged into the white sand, rose to . degrees. in the small pools of salt water it kept at . degrees, while the heat of the ocean, at its surface, is generally, in the port of cumana, from . to . degrees. the first plant we gathered on the continent of america was the avicennia tomentosa, (* mangle prieto.) which in this place scarcely reaches two feet in height. this shrub, together with the sesuvium, the yellow gomphrena, and the cactus, cover soil impregnated with muriate of soda; they belong to that small number of plants which live in society like the heath of europe, and which in the torrid zone are found only on the seashore, and on the elevated plains of the andes.* (* on the extreme rarity of the social plants in the tropics, see my essay on the geog. of plants page ; and a paper by mr. brown on the proteacea, transactions of the lin. soc. volume page , page , in which that great botanist has extended and confirmed by numerous facts my ideas on the association of plants of the same species.) the avicennia of cumana is distinguished by another peculiarity not less remarkable: it furnishes an instance of a plant common to the shores of south america and the coasts of malabar. the indian pilot led us across his garden, which rather resembled a copse than a piece of cultivated ground. he showed us, as a proof of the fertility of this climate, a silk-cotton tree (bombax heptaphyllum), the trunk of which, in its fourth year, had reached nearly two feet and a half in diameter. we have observed, on the banks of the orinoco and the river magdalena, that the bombax, the carolinea, the ochroma, and other trees of the family of the malvaceae, are of extremely rapid growth. i nevertheless think that there was some exaggeration in the report of the indian respecting the age of his bombax; for under the temperate zone, in the hot and damp lands of north america, between the mississippi and the alleghany mountains, the trees do not exceed a foot in diameter, in ten years. vegetation in those parts is in general but a fifth more speedy than in europe, even taking as an example the platanus occidentalis, the tulip tree, and the cupressus disticha, which reach from nine to fifteen feet in diameter. on the strand of cumana, in the garden of the guayqueria pilot, we saw for the first time a guama* loaded with flowers, and remarkable for the extreme length and silvery splendour of its numerous stamina. (* inga spuria, which we must not confound with the common inga, inga vera, willd. (mimosa inga, linn.). the white stamina, which, to the number of sixty or seventy, are attached to a greenish corolla, have a silky lustre, and are terminated by a yellow anther. the flower of the guama is eighteen lines long. the common height of this fine tree, which prefers a moist soil, is from eight to ten toises.) we crossed the suburb of the guayqueria indians, the streets of which are very regular, and formed of small houses, quite new, and of a pleasing appearance. this part of the town had just been rebuilt, for the earthquake had laid cumana in ruins eighteen months before our arrival. by a wooden bridge, we crossed the river manzanares, which contains a few bavas, or crocodiles of the smaller species. we were conducted by the captain of the pizarro to the governor of the province, don vincente emparan, to present to him the passports furnished to us by the first secretary of state at madrid. he received us with that frankness and unaffected dignity which have at all times characterized the natives of biscay. before he was appointed governor of portobello and cumana, don vincente emparan had distinguished himself as captain of a vessel in the navy. his name recalls to mind one of the most extraordinary and distressing events recorded in the history of maritime warfare. at the time of the last rupture between spain and england, two brothers of senor emperan, both of whom commanded ships in the spanish navy, engaged with each other before the port of cadiz, each supposing that he was attacking an enemy. a fierce battle was kept up during a whole night, and both the vessels were sunk almost simultaneously. a very small part of the crew was saved, and the two brothers had the misfortune to recognize each other a little before they expired. the governor of cumana expressed his great satisfaction at the resolution we had taken to remain for some time in new andalusia, a province which at that period was but little known even by name in europe, and which in its mountains, and on the banks of its numerous rivers, contains a great number of objects worthy of fixing the attention of naturalists. senor emperan showed us cottons dyed with native plants, and fine furniture made exclusively of the wood of the country. he was much interested in everything that related to natural philosophy; and asked, to our great astonishment, whether we thought, that, under the beautiful sky of the tropics, the atmosphere contained less azote (azotico) than in spain; or whether the rapidity with which iron oxidates in those climates, were only the effect of greater humidity as indicated by the air hygrometer. the name of his native country pronounced on a distant shore would not have been more agreeable to the ear of a traveller, than those words azote, oxide of iron, and hygrometer, were to ours. senor emparan was a lover of science, and the public marks of consideration which he gave us during a long abode in his government, contributed greatly to procure us a favourable welcome in every part of south america. we hired a spacious house, the situation of which was favourable for astronomical observations. we enjoyed an agreeable coolness when the breeze arose; the windows were without glass, and even without those paper panes which are often substituted for glass at cumana. the whole of the passengers of the pizarro left the vessel, but the recovery of those who had been attacked by the fever was very slow. we saw some who, a month after, notwithstanding the care bestowed on them by their countrymen, were still extremely weak and reduced. hospitality, in the spanish colonies, is such, that a european who arrives, without recommendation or pecuniary means, is almost sure of finding assistance, if he land in any port on account of sickness. the catalonians, the galicians, and the biscayans, have the most frequent intercourse with america. they there form as it were three distinct corporations, which exercise a remarkable influence over the morals, the industry, and commerce of the colonies. the poorest inhabitant of siges or vigo is sure of being received into the house of a catalonian or galician pulpero,* (* a retail dealer.) whether he land in chile or the philippine islands. among the sick who landed at cumana was a negro, who fell into a state of insanity a few days after our arrival; he died in that deplorable condition, though his master, almost seventy years old, who had left europe to settle at san blas, at the entrance of the gulf of california, had attended him with the greatest care. i relate this fact as affording evidence that men born under the torrid zone, after having dwelt in temperate climates, sometimes feel the pernicious effects of the heat of the tropics. the negro was a young man, eighteen years of age, very robust, and born on the coast of guinea; an abode of some years on the high plain of castile, had imparted to his organization that kind of irritability which renders the miasma of the torrid zone so dangerous to the inhabitants of the countries of the north. the site on which cumana is built is part of a tract of ground, very remarkable in a geological point of view. the chain of the calcareous alps of the brigantine and the tataraqual stretches east and west from the summit of the imposible to the port of mochima and to campanario. the sea, in times far remote, appears to have divided this chain from the rocky coasts of araya and maniquarez. the vast gulf of cariaco has been caused by an irruption of the sea; and no doubt can be entertained but that the waters once covered, on the southern bank, the whole tract of land impregnated with muriate of soda, through which flows the manzanares. the slow retreat of the waters has turned into dry ground this extensive plain, in which rises a group of small hills, composed of gypsum and calcareous breccias of very recent formation. the city of cumana is backed by this group, which was formerly an island of the gulf of cariaco. that part of the plain which is north of the city, is called plaga chica, or the little plain, and extends eastwards as far as punta delgada, where a narrow valley, covered with yellow gomphrena, still marks the point of the ancient outlet of the waters. the hill of calcareous breccias, which we have just mentioned as having once been an island in the ancient gulf, is covered with a thick forest of cylindric cactus and opuntia. some of these trees, thirty or forty feet high, are covered with lichens, and are divided into several branches in the form of candelabra. near maniquarez, at punta araya, we measured a cactus,* the trunk of which was four feet nine inches in circumference (* tuna macho. we distinguish in the wood of the cactus the medullary prolongations, as m. desfontaines has already observed.). a european acquainted only with the opuntia in our hot-houses is surprised to see the wood of this plant become so hard from age, that it resists for centuries both air and moisture: the indians of cumana therefore employ it in preference to any other for oars and door-posts. cumana, coro, the island of margareta, and curassao, are the parts of south america that abound most in plants of the nopal family. there only, a botanist, after a long residence, could compose a monography of the genus cactus, the species of which vary not only in their flowers and fruits, but also in the form of their articulated stems, the number of costae, and the disposition of the thorns. we shall see hereafter how these plants, which characterize a warm and singularly dry climate, like that of egypt and california, gradually disappear in proportion as we remove from the coasts, and penetrate into the inland country. the groups of columnar cactus and opuntia produce the same effect in the arid lands of equinoctial america as the junceae and the hydrocharides in the marshes of our northern climes. places in which the larger species of the strong cactus are collected in groups are considered as almost impenetrable. these places are called tunales; and they are impervious not only to the native, who goes naked to the waist, but are formidable even to those who are fully clothed. in our solitary rambles we sometimes endeavoured to penetrate into the tunal that crowns the summit of the castle hill, a part of which is crossed by a pathway, where we could have studied, amidst thousands of specimens, the organization of this singular plant. sometimes night suddenly overtook us, for there is scarcely any twilight in this climate; and we then found ourselves dangerously situated, as the cascabel, or rattle-snake, the coral, and other vipers armed with poisonous fangs, frequent these scorched and arid haunts, to deposit their eggs in the sand. the castle of san antonio is built at the western extremity of the hill, but not on the most elevated point, being commanded on the east by an unfortified summit. the tunal is considered both here and everywhere in the spanish colonies as a very important means of military defence; and when earthen works are raised, the engineers are eager to propagate the thorny opuntia, and promote its growth, as they are careful to keep crocodiles in the ditches of fortified places. in regions where organized nature is so powerful and active, man summons as auxiliaries in his defence the carnivorous reptile, and the plant with its formidable armour of thorns. the castle is only thirty toises above the level of the water in the gulf of cariaco. standing on a naked and calcareous hill, it commands the town, and has a very picturesque effect when viewed from a vessel entering the port. it forms a bright object against the dark curtains of those mountains which raise their summits to the clouds, and of which the vaporous and bluish tint blends with the azure sky. on descending from fort san antonio to the south-west, we find on the slope of the same rock the ruins of the old castle of santa maria. this site is delightful to those who wish to enjoy at the approach of sunset the freshness of the breeze and the view of the gulf. the lofty summits of the island of margareta are seen above the rocky coast of the isthmus of araya, and towards the west the small islands of caracas, picuita, and boracha, recall to mind the catastrophes that have overwhelmed the coasts of terra firma. these islets resemble fortifications, and from the effect of the mirage (while the inferior strata of the air, the ocean, and the soil, are unequally heated by the sun), their points appear raised like the extremity of the great promontories of the coast. it is pleasing, during the day, to observe these inconstant phenomena; we see, as night approaches, these stony masses which had been suspended in the air, settle down on their bases; and the luminary, whose presence vivifies organic nature, seems by the variable inflection of its rays to impress motion on the stable rock, and give an undulating movement to plains covered with arid sands.* (* the real cause of the mirage, or the extraordinary refraction which the rays undergo when strata of air of different densities lie over each other, was guessed at by hooke.--see his posthumous works page .) the town of cumana, properly so called, occupies the ground lying between the castle of san antonio and the small rivers of manzanares and santa catalina. the delta, formed by the bifurcation of the first of these rivers, is a fertile plain covered with mammees, sapotas (achras), plantains, and other plants cultivated in the gardens or charas of the indians. the town has no remarkable edifice, and the frequency of earthquakes forbids such embellishments. it is true, that strong shocks occur less frequently in a given time at cumana than at quito, where we nevertheless find sumptuous and very lofty churches. but the earthquakes of quito are violent only in appearance, and, from the peculiar nature of the motion and of the ground, no edifice there is overthrown. at cumana, as well as at lima, and in several cities situated far from the mouths of burning volcanoes, it happens that the series of slight shocks is interrupted after a long course of years by great catastrophes, resembling the effects of the explosion of a mine. we shall have occasion to return to this phenomenon, for the explanation of which so many vain theories have been imagined, and which have been classified according to perpendicular and horizontal movements, shock, and oscillation.* (* this classification dates from the time of posidonius. it is the successio and inclinatio of seneca; but the ancients had already judiciously remarked, that the nature of these shocks is too variable to permit any subjection to these imaginary laws.) the suburbs of cumana are almost as populous as the ancient town. they are three in number:--serritos, on the road to the plaga chicha, where we meet with some fine tamarind trees; st. francis, towards the south-east; and the great suburb of the guayquerias, or guayguerias. the name of this tribe of indians was quite unknown before the conquest. the natives who bear that name formerly belonged to the nation of the guaraounos, of which we find remains only in the swampy lands of the branches of the orinoco. old men have assured me that the language of their ancestors was a dialect of the guaraouno; but that for a century past no native of that tribe at cumana, or in the island of margareta, has spoken any other language than castilian. the denomination guayqueria, like the words peru and peruvian, owes its origin to a mere mistake. the companions of christopher columbus, coasting along the island of margareta, the northern coast of which is still inhabited by the noblest portion of the guayqueria nation,* (* the guayquerias of la banda del norte consider themselves as the most noble race, because they think they are less mixed with the chayma indian, and other copper-coloured races. they are distinguished from the guayquerias of the continent by their manner of pronouncing the spanish language, which they speak almost without separating their teeth. they show with pride to europeans the punta de la galera, or galley's point, (so called on account of the vessel of columbus having anchored there), and the port of manzanillo, where they first swore to the whites in , that friendship which they have never betrayed, and which has obtained for them, in court phraseology, the title of fieles, loyal.--see above.) encountered a few natives who were harpooning fish by throwing a pole tied to a cord, and terminating in an extremely sharp point. they asked them in the haiti language their name; and the indians, thinking that the question of the strangers related to their harpoons, which were formed of the hard and heavy wood of the macana palm, answered guaike, guaike, which signifies pointed pole. a striking difference at present exists between the guayquerias, a civilized tribe of skilled fishermen, and those savage guaraounos of the orinoco, who suspend their habitations on the trunks of the moriche palm. the population of cumana has been singularly exaggerated, but according to the most authentic registers it does not exceed , souls. probably the indian suburb will by degrees extend as far as the embarcadero; the plain, which is not yet covered with houses or huts, being more than toises in length. the heat is somewhat less oppressive on the side near the seashore, than in the old town, where the reverberation of the calcareous soil, and the proximity of the mountain of san antonio, raise the temperature to an excessive degree. in the suburb of the guayquerias, the sea breezes have free access; the soil is clayey, and, for that reason, it is thought to be less exposed to violent shocks of earthquake, than the houses at the foot of the rocks and hills on the right bank of the manzanares. the shore near the mouth of the small river santa catalina is bordered with mangrove trees,* but these mangroves are not sufficiently spread to diminish the salubrity of the air of cumana. (* rhizophora mangle. m. bonpland found on the plaga chica the allionia incarnata, in the same place where the unfortunate loefling had discovered this new genus of nyctagineae.) the soil of the plain is in part destitute of vegetation, in part covered with tufts of sesuvium portulacastrum, gomphrena flava, g. myrtifolia, talinum cuspidatum, t. cumanense, and portulaca lanuginosa. among these herbaceous plants we find at intervals the avicennia tomentosa, the scoparia dulcis, a frutescent mimosa with very irritable leaves,* and particularly cassias, the number of which is so great in south america, that we collected, in our travels, more than thirty new species. (* the spaniards designate by the name of dormideras (sleeping plants), the small number of mimosas with irritable leaves. we have increased this number by three species previously unknown to botanists, namely, the mimosa humilis of cumana, the m. pellita of the savannahs of calabozo, and the m. dormiens of the banks of the apure.) on leaving the indian suburb, and ascending the river southward, we found a grove of cactus, a delightful spot, shaded by tamarinds, brazilettos, bombax, and other plants, remarkable for their leaves and flowers. the soil here is rich in pasturage, and dairy-houses built with reeds, are separated from each other by clumps of trees. the milk remains fresh, when kept, not in the calabashes* of very thick ligneous fibres (* these calabashes are made from the fruit of the crescentia cujete.), but in porous earthen vessels from maniquarez. a prejudice prevalent in northern countries had long led me to believe, that cows, under the torrid zone, did not yield rich milk; but my abode at cumana, and especially an excursion through the vast plains of calabozo, covered with grasses, and herbaceous sensitive plants, convinced me that the ruminating animals of europe become perfectly habituated to the hottest climates, provided they find water and good nourishment. milk is excellent in the provinces of new andalusia, barcelona, and venezuela; and butter is better in the plains of the equinoctial zone, than on the ridge of the andes, where the alpine plants, enjoying in no season a sufficiently high temperature, are less aromatic than on the pyrenees, on the mountains of estremadura, or of greece. as the inhabitants of cumana prefer the coolness of the sea breeze to the sight of vegetation, their favourite walk is the open shore. the spaniards, who in general have no great predilection for trees, or for the warbling of birds, have transported their tastes and their habits into the colonies. in terra firma, mexico, and peru, it is rare to see a native plant a tree, merely with the view of procuring shade; and if we except the environs of the great capitals, walks bordered with trees are almost unknown in those countries. the arid plain of cumana exhibits after violent showers an extraordinary phenomenon. the earth, when drenched with rain, and heated again by the rays of the sun, emits that musky odour which in the torrid zone, is common to animals of very different classes, namely: to the jaguar, the small species of tiger cat, the cabiai or thick-nosed tapir,* (* cavia capybara, linn.; chiguire.) the galinazo vulture,* (* vultur aura, linn., zamuro, or galinazo: the brazilian vulture of buffon. i cannot reconcile myself to the adoption of names, which designate, as belonging to a single country, animals common to a whole continent.) the crocodile, the viper, and the rattlesnake. the gaseous emanations, which are the vehicles of this aroma, seem to be evolved in proportion only as the mould, containing the spoils of an innumerable quantity of reptiles, worms, and insects, begins to be impregnated with water. i have seen indian children, of the tribe of the chaymas, draw out from the earth and eat millipedes or scolopendras* eighteen inches long, and seven lines broad. (* scolopendras are very common behind the castle of san antonio, on the summit of the hill.) whenever the soil is turned up, we are struck with the mass of organic substances, which by turns are developed, transformed, and decomposed. nature in these climates appears more active, more fruitful, we may even say more prodigal, of life. on this shore, and near the dairies just mentioned, we enjoy, especially at sunrise, a very beautiful prospect over an elevated group of calcareous mountains. as this group subtends an angle of three degrees only at the house where we dwelt, it long served me to compare the variations of the terrestrial refraction with the meteorological phenomena. storms are formed in the centre of this cordillera; and we see from afar thick clouds resolve into abundant rains, while during seven or eight months not a drop of water falls at cumana. the brigantine, which is the highest part of this chain, raises itself in a very picturesque manner behind brito and tataraqual. it takes its name from the form of a very deep valley on the northern declivity, which resembles the interior of a ship. the summit of this mountain is almost bare of vegetation, and is flat like that of mowna roa, in the sandwich islands. it is a perpendicular wall, or, to use a more expressive term of the spanish navigators, a table (mesa). this peculiar form, and the symmetrical arrangement of a few cones which surround the brigantine, made me at first think that this group, which is wholly calcareous, contained rocks of basaltic or trappean formation. the governor of cumana sent, in , a band of determined men to explore this entirely desert country, and to open a direct road to new barcelona, by the summit of the mesa. it was reasonably expected that this way would be shorter, and less dangerous to the health of travellers, than the route taken by the couriers along the coasts; but every attempt to cross the chain of the mountains of the brigantine was fruitless. in this part of america, as in australia* to the west of sydney, it is not so much the height of the mountain chains, as the form of the rocks, that presents obstacles difficult to surmount. (* the blue mountains of australia, and those of carmarthen and lansdowne, are not visible, in clear weather, beyond fifty miles.--peron, voyage aux terres australes page . supposing the angle of altitude half a degree, the absolute height of these mountains would be about toises.) the longitudinal valley formed by the lofty mountains of the interior and the southern declivity of the cerro de san antonio, is intersected by the rio manzanares. this plain, the only thoroughly wooded part in the environs of cumana, is called the plain of the charas,* on account of the numerous plantations which the inhabitants have begun, for some years past, along the river. (* chacra, by corruption chara, signifies a hut or cottage surrounded by a garden. the word ipure has the same signification.) a narrow path leads from the hill of san francisco across the forest to the hospital of the capuchins, a very agreeable country-house, which the aragonese monks have built as a retreat for old infirm missionaries, who can no longer fulfil the duties of their ministry. as we advance to the west, the trees of the forest become more vigorous, and we meet with a few monkeys,* (* the common machi, or weeping monkey.) which, however, are very rare in the environs of cumana. at the foot of the capparis, the bauhinia, and the zygophyllum with flowers of a golden yellow, there extends a carpet of bromelia,* (* chihuchihue, of the family of the ananas.) akin to the b. karatas, which from the odour and coolness of its foliage attracts the rattlesnake. the waters of the manzanares are very limpid in quality, and this river has no resemblance to the manzanares of madrid, which appears the more magnificent in contrast with the fine bridge by which it is crossed. it takes its source, like all the rivers of new andalusia, in the savannahs (llanos) known by the names of the plateaux of jonoro, amana, and guanipa,* (* these three eminences bear the names of mesas, tables. an immense plain has an almost imperceptible rise from both sides to the middle, without any appearance of mountains or hills.) and it receives, near the indian village of san fernando, the waters of the rio juanillo. it has been several times proposed to the government, but without success, to construct a dyke at the first ipure, in order to form artificial irrigations in the plain of charas; for, notwithstanding its apparent sterility, the soil is extremely productive, wherever humidity is combined with the heat of the climate. the cultivators were gradually to refund the money advanced for the construction of the sluices. meanwhile, pumps worked by mules, and other hydraulic but imperfect machines, have been erected, to serve till this project is carried into execution. the banks of the manzanares are very pleasant, and are shaded by mimosas, erythrinas, ceibas, and other trees of gigantic growth. a river, the temperature of which, in the season of the floods, descends as low as twenty-two degrees, when the air is at thirty and thirty-three degrees, is an inestimable benefit in a country where the heat is excessive during the whole year, and where it is so agreeable to bathe several times in the day. the children pass a considerable part of their lives in the water; all the inhabitants, even the women of the most opulent families, know how to swim; and in a country where man is so near the state of nature, one of the first questions asked on meeting in the morning is, whether the water is cooler than it was on the preceding evening. one of the modes of bathing is curious. we every evening visited a family, in the suburb of the guayquerias. in a fine moonlight night, chairs were placed in the water; the men and women were lightly clothed, as in some baths of the north of europe; and the family and strangers, assembled in the river, passed some hours in smoking cigars, and in talking, according to the custom of the country, of the extreme dryness of the season, of the abundant rains in the neighbouring districts, and particularly of the extravagancies of which the ladies of cumana accuse those of caracas and the havannah. the company were under no apprehensions from the bavas, or small crocodiles, which are now extremely scarce, and which approach men without attacking them. these animals are three or four feet long. we never met with them in the manzanares, but with a great number of dolphins (toninas), which sometimes ascend the river in the night, and frighten the bathers by spouting water. the port of cumana is a roadstead capable of receiving the fleets of europe. the whole of the gulf of cariaco, which is about miles long and broad, affords excellent anchorage. the pacific is not more calm on the shores of peru, than the caribbean sea from porto-cabello, and especially from cape codera to the point of paria. the hurricanes of the west indies are never felt in these regions. the only danger in the port of cumana is a shoal, called morro roxo. there are from one to three fathoms water on this shoal, while just beyond its edges there are eighteen, thirty, and even thirty-eight. the remains of an old battery, situated north-north-east of the castle of san antonio, and very near it, serve as a mark to avoid the bank of morro roxo. the city lies at the foot of a hill destitute of verdure, and is commanded by a castle. no steeple or dome attracts from afar the eye of the traveller, but only a few trunks of tamarind, cocoa, and date trees, which rise above the houses, the roofs of which are flat. the surrounding plains, especially those on the coasts, wear a melancholy, dusty, and arid appearance, while a fresh and luxuriant vegetation marks from afar the windings of the river, which separates the city from the suburbs; the population of european and mixed race from the copper-coloured natives. the hill of fort san antonio, solitary, white, and bare, reflects a great mass of light, and of radiant heat: it is composed of breccia, the strata of which contain numerous fossils. in the distance, towards the south, stretches a vast and gloomy curtain of mountains. these are the high calcareous alps of new andalusia, surmounted by sandstone, and other more recent formations. majestic forests cover this cordillera of the interior, and they are joined by a woody vale to the open clayey lands and salt marshes of the environs of cumana. a few birds of considerable size contribute to give a peculiar character to these countries. on the seashore, and in the gulf, we find flocks of fishing herons, and alcatras of a very unwieldy form, which swim, like the swan, raising their wings. nearer the habitation of man, thousands of galinazo vultures, the jackals of the winged tribe, are ever busy in disinterring the carcases of animals.* (* buffon hist. nat. des oiseaux tome page .) a gulf, containing hot and submarine springs, divides the secondary from the primary and schistose rocks of the peninsula of araya. each of these coasts is washed by a tranquil sea, of azure tint, and always gently agitated by a breeze from one quarter. a bright clear sky, with a few light clouds at sunset, reposes on the ocean, on the treeless peninsula, and on the plains of cumana, while we see the storms accumulate and descend in fertile showers among the inland mountains. thus on these coasts, as well as at the foot of the andes, the earth and the sky present the extremes of clear weather and fogs, of drought and torrents of rain, of absolute nudity and never-ceasing verdure. the analogies which we have just indicated, between the sea-coasts of new andalusia and those of peru, extend also to the recurrence of earthquakes, and the limits which nature seems to have prescribed to these phenomena. we have ourselves felt very violent shocks at cumana; and we learned on the spot, the most minute circumstances that accompanied the great catastrophe of the th december, . it is a very generally received opinion on the coasts of cumana, and in the island of margareta, that the gulf of cariaco owes its existence to a rent of the continent attended by an irruption of the sea. the remembrance of that great event was preserved among the indians to the end of the fifteenth century; and it is related that, at the time of the third voyage of christopher columbus, the natives mentioned it as of very recent date. in , the inhabitants were alarmed by new shocks on the coasts of paria and cumana. the land was inundated by the sea, and the small fort, built by james castellon at new toledo,* was entirely destroyed. (* this was the first name given to the city of cumana--girolamo benzoni hist. del mondo nuovo pages , , and . james castellon arrived at st. domingo in , after the appearance of the celebrated bartholomew de las casas in these countries. on attentively reading the narratives of benzoni and caulin, we find that the fort of castellon was built near the mouth of the manzanares (alla ripa del fiume de cumana); and not, as some modern travellers have asserted, on the mountain where now stands the castle of san antonio.) at the same time an enormous opening was formed in the mountains of cariaco, on the shores of the gulf bearing that name, when a great body of salt-water, mixed with asphaltum, issued from the micaceous schist. earthquakes were very frequent about the end of the sixteenth century; and, according to the traditions preserved at cumana, the sea often inundated the shores, rising from fifteen to twenty fathoms. as no record exists at cumana, and its archives, owing to the continual devastations of the termites, or white ants, contain no document that goes back farther than a hundred and fifty years, we are unacquainted with the precise dates of the ancient earthquakes. we only know, that, in times nearer our own, the year was at once the most fatal to the colonists, and the most remarkable for the physical history of the country. the city of cumana was entirely destroyed, the houses were overturned in the space of a few minutes, and the shocks were hourly repeated during fourteen months. in several parts of the province the earth opened, and threw out sulphureous waters. these irruptions were very frequent in a plain extending towards casanay, two leagues east of the town of cariaco, and known by the name of the hollow ground (tierra hueca), because it appears entirely undermined by thermal springs. during the years and , the inhabitants of cumana encamped in their streets; and they began to rebuild their houses only when the earthquakes recurred once a month. what was felt at quito, immediately after the great catastrophe of february , took place on these coasts. while the ground was in a state of continual oscillation, the atmosphere seemed to dissolve itself into water. tradition states that in the earthquake of , as well as in another remarkable one in , the shocks were mere horizontal oscillations; it was only on the disastrous th of december, , that for the first time at cumana the motion was felt by an upheaving of the ground. more than four-fifths of the city were then entirely destroyed; and the shock, attended by a very loud subterraneous noise, resembled, as at riobamba, the explosion of a mine at a great depth. happily the most violent shock was preceded by a slight undulating motion, so that most of the inhabitants were enabled to escape into the streets, and a small number only perished of those who had assembled in the churches. it is a generally received opinion at cumana, that the most destructive earthquakes are announced by very feeble oscillations, and by a hollow sound, which does not escape the observation of persons habituated to this kind of phenomenon. in those fatal moments the cries of 'misericordia! tembla! tembla!'* are everywhere heard (* "mercy! the earthquake! the earthquake!"--see tschudi's travels in peru page .); and it rarely happens that a false alarm is given by a native. those who are most apprehensive attentively observe the motions of dogs, goats, and swine. the last-mentioned animals, endowed with delicate olfactory nerves, and accustomed to turn up the earth, give warning of approaching danger by their restlessness and their cries. we shall not attempt to decide, whether, being nearer the surface of the ground, they are the first to hear the subterraneous noise; or whether their organs receive the impression of some gaseous emanation which issues from the earth. we cannot deny the possibility of this latter cause. during my abode at peru, a fact was observed in the inland country, which has an analogy with this kind of phenomenon, and which is not unfrequent. at the end of violent earthquakes, the herbs that cover the savannahs of tucuman acquired noxious properties; an epidemic disorder broke out among the cattle, and a great number of them appeared stupified or suffocated by the deleterious vapours exhaled from the ground. at cumana, half an hour before the catastrophe of the th of december, , a strong smell of sulphur was perceived near the hill of the convent of san francisco; and on the same spot the subterraneous noise, which seemed to proceed from south-east to north-west, was loudest. at the same time flames appeared on the banks of the manzanares, near the hospital of the capuchins, and in the gulf of cariaco, near mariguitar. this last phenomenon, so extraordinary in a country not volcanic, is pretty frequent in the alpine calcareous mountains near cumanacoa, in the valley of bordones, in the island of margareta, and amidst the llanos or savannahs of new andalusia. in these savannahs, flakes of fire rising to a considerable height, are seen for hours together in the dryest places; and it is asserted, that, on examining the ground no crevice is perceptible. this fire, which resembles the springs of hydrogen, or salse, of modena, or what is called the will-o'-the-wisp of our marshes, does not burn the grass; because, no doubt, the column of gas, which develops itself, is mixed with azote and carbonic acid, and does not burn at its basis. the people, although less superstitious here than in spain, call these reddish flames by the singular name of 'the soul of the tyrant aguirre;' imagining that the spectre of lopez aguirre, harassed by remorse, wanders over these countries sullied by his crimes.* (* when at cumana, or in the island of margareta, the people pronounce the words el tirano (the tyrant), it is always to denote the hated lopez d'aguirre, who, after having taken part, in , in the revolt of fernando de guzman against pedro de ursua, governor of the omeguas and dorado, voluntarily took the title of traidor, or traitor. he descended the river amazon with his band, and reached by a communication of the rivers of guyana the island of margareta. the port of paraguache still bears, in this island, the name of the tyrant's port.) the great earthquake of produced some changes in the configuration of the shoal of morro roxo, towards the mouth of the rio bordones. similar swellings were observed at the time of the total destruction of cumana, in . at that period, the punta delgado, on the southern coast of the gulf of cariaco, became perceptibly enlarged; and in the rio guarapiche, near the village of maturin, a shoal was formed, no doubt by the action of the elastic fluids, which displaced and raised up the bed of the river. in order to follow a plan conformable to the end we proposed in this work, we shall endeavour to generalize our ideas, and to comprehend in one point of view everything that relates to these phenomena, so terrific, and so difficult to explain. if it be the duty of the men of science who visit the alps of switzerland, or the coasts of lapland, to extend our knowledge respecting the glaciers and the aurora borealis, it may be expected that a traveller who has journeyed through spanish america, should have chiefly fixed his attention on volcanoes and earthquakes. each part of the globe is an object of particular study; and when we cannot hope to penetrate the causes of natural phenomena, we ought at least to endeavour to discover their laws, and distinguish, by the comparison of numerous facts, that which is permanent and uniform from that which is variable and accidental. the great earthquakes, which interrupt the long series of slight shocks, appear to have no regular periods at cumana. they have taken place at intervals of eighty, a hundred, and sometimes less than thirty years; while on the coasts of peru, for instance at lima, a certain regularity has marked the periods of the total destruction of the city. the belief of the inhabitants in the existence of this uniformity has a happy influence on public tranquillity, and the encouragement of industry. it is generally admitted, that it requires a sufficiently long space of time for the same causes to act with the same energy; but this reasoning is just only inasmuch as the shocks are considered as a local phenomenon; and a particular focus, under each point of the globe exposed to those great catastrophes, is admitted. whenever new edifices are raised on the ruins of the old, we hear from those who refuse to build, that the destruction of lisbon on the first day of november, , was soon followed by a second, and not less fatal convulsion, on the st of march, . it is a very ancient opinion,* (* aristotle de meteor. lib. (ed. duval, tome page ). seneca nat. quaest. lib. c. .) and one that is commonly received at cumana, acapulco, and lima, that a perceptible connection exists between earthquakes and the state of the atmosphere that precedes those phenomena. but from the great number of earthquakes which i have witnessed to the north and south of the equator; on the continent, and on the seas; on the coasts, and at toises height; it appears to me that the oscillations are generally very independent of the previous state of the atmosphere. this opinion is entertained by a number of intelligent residents of the spanish colonies, whose experience extends, if not over a greater space of the globe, at least over a greater number of years, than mine. on the contrary, in parts of europe where earthquakes are rare compared to america, scientific observers are inclined to admit an intimate connection between the undulations of the ground, and certain meteors, which appear simultaneously with them. in italy for instance, the sirocco and earthquakes are suspected to have some connection; and in london, the frequency of falling-stars, and those southern lights which have since been often observed by mr. dalton, were considered as the forerunners of those shocks which were felt from to . on days when the earth is shaken by violent shocks, the regularity of the horary variations of the barometer is not disturbed within the tropics. i had opportunities of verifying this observation at cumana, at lima, and at riobamba; and it is the more worthy of attention, as at st. domingo, (in the town of cape francois,) it is asserted, that a water-barometer sank two inches and a half immediately before the earthquake of . it is also related, that, at the time of the destruction of oran, a druggist fled with his family, because, observing accidentally, a few minutes before the earthquake, the height of the mercury in his barometer, he perceived that the column sank in an extraordinary manner. i know not whether we can give credit to this story; but as it is nearly impossible to examine the variations of the weight of the atmosphere during the shocks, we must be satisfied with observing the barometer before or after these phenomena have taken place. we can scarcely doubt, that the earth, when opened and agitated by shocks, spreads occasionally gaseous emanations through the atmosphere, in places remote from the mouths of volcanoes not extinct. at cumana, it has already been observed that flames and vapours mixed with sulphurous acid spring up from the most arid soil. in other parts of the same province, the earth ejects water and petroleum. at riobamba, a muddy and inflammable mass, called moya, issues from crevices that close again, and accumulates into elevated hills. at about seven leagues from lisbon, near colares, during the terrible earthquake of the st of november, , flames and a column of thick smoke were seen to issue from the flanks of the rocks of alvidras, and, according to some witnesses, from the bosom of the sea. elastic fluids thrown into the atmosphere may act locally on the barometer, not by their mass, which is very small, compared to the mass of the atmosphere, but because, at the moment of great explosions, an ascending current is probably formed, which diminishes the pressure of the air. i am inclined to think that in the majority of earthquakes nothing escapes from the agitated earth; and that, when gaseous emanations and vapours are observed, they oftener accompany or follow, than precede the shocks. this circumstance would seem to explain the mysterious influence of earthquakes in equinoctial america, on the climate, and on the order of the dry and rainy seasons. if the earth generally act on the air only at the moment of the shocks, we can conceive why a sensible meteorological change so rarely precedes those great revolutions of nature. the hypothesis according to which, in the earthquakes of cumana, elastic fluids tend to escape from the surface of the soil, seems confirmed by the great noise which is heard during the shocks at the borders of the wells in the plain of charas. water and sand are sometimes thrown out twenty feet high. similar phenomena were observed in ancient times by the inhabitants of those parts of greece and asia minor abounding with caverns, crevices, and subterraneous rivers. nature, in her uniform progress, everywhere suggests the same ideas of the causes of earthquakes, and the means by which man, forgetting the measure of his strength, pretends to diminish the effect of the subterraneous explosions. what a great roman naturalist has said of the utility of wells and caverns* is repeated in the new world by the most ignorant indians of quito, when they show travellers the guaicos, or crevices of pichincha. (* "in puteis est remedium, quale et crebri specus praebent: conceptum enim spiritum exhalant: quod in certis notatur oppidis, quae minus quatiuntur, crebris ad eluviem cuniculis cavata."--pliny lib. c. (ed. par. t. page .) even at present, in the capital of st. domingo, wells are considered as diminishing the violence of the shocks. i may observe on this occasion, that the theory of earthquakes, given by seneca, (nat. quaest. lib. c. - ), contains the germ of everything that has been said in our times on the action of the elastic vapours confined in the interior of the globe.) the subterranean noise, so frequent during earthquakes, is generally not in the ratio of the force of the shocks. at cumana it constantly precedes them, while at quito, and recently at caracas, and in the west india islands, a noise like the discharge of a battery was heard a long time after the shocks had ceased. a third kind of phenomenon, the most remarkable of the whole, is the rolling of those subterranean thunders, which last several months, without being accompanied by the least oscillatory motion of the ground.* (* the subterranean thunders (bramidos y truenos subterraneos) of guanaxuato. the phenomenon of a noise without shocks was observed by the ancients.--aristot. meteor. lib. (ed. duval page ). pliny lib. c. .) in every country subject to earthquakes, the point at which, probably owing to a particular disposition of the stony strata, the effects are most sensibly felt, is considered as the cause and the focus of the shocks. thus, at cumana, the hill of the castle of san antonio, and particularly the eminence on which stands the convent of st. francis, are believed to contain an enormous quantity of sulphur and other inflammable matter. we forget that the rapidity with which the undulations are propagated to great distances, even across the basin of the ocean, proves that the centre of action is very remote from the surface of the globe. from this same cause no doubt earthquakes are not confined to certain species of rocks, as some naturalists suppose, but all are fitted to propagate the movement. keeping within the limits of my own experience i may here cite the granites of lima and acapulco; the gneiss of caracas; the mica-slate of the peninsula of araya; the primitive thonschiefer of tepecuacuilco, in mexico; the secondary limestones of the apennines, spain, and new andalusia; and finally, the trappean porphyries of the provinces of quito and popayan.* (* i might add to the list of secondary rocks, the gypsum of the newest formation, for instance, that of montmartre, situated on a marine calcareous rock, which is posterior to the chalk.--see the memoires de l'academie tome page on the earthquake felt at paris and its environs in .) in these different places the ground is frequently agitated by the most violent shocks; but sometimes, in the same rock, the superior strata form invincible obstacles to the propagation of the motion. thus, in the mines of saxony, we have seen workmen hasten up alarmed by oscillations which were not felt at the surface of the ground. if, in regions the most remote from each other, primitive, secondary, and volcanic rocks, share equally in the convulsive movements of the globe; we cannot but admit also that within a space of little extent, certain classes of rocks oppose themselves to the propagation of the shocks. at cumana, for instance, before the great catastrophe of , the earthquakes were felt only along the southern and calcareous coast of the gulf of cariaco, as far as the town of that name; while in the peninsula of araya, and at the village of maniquarez, the ground did not share the same agitation. but since december , new communications appear to have been opened in the interior of the globe. the peninsula of araya is now not merely subject to the same agitations as the soil of cumana, but the promontory of mica-slate, previously free from earthquakes, has become in its turn a central point of commotion. the earth is sometimes strongly shaken at the village of maniquarez, when on the coast of cumana the inhabitants enjoy the most perfect tranquillity. the gulf of cariaco, nevertheless, is only sixty or eighty fathoms deep. it has been thought from observations made both on the continent and in the islands, that the western and southern coasts are most exposed to shocks. this observation is connected with opinions which geologists have long formed respecting the position of the high chains of mountains, and the direction of their steepest declivities; but the existence of the cordillera of caracas, and the frequency of the oscillations on the eastern and northern coast of terra firma, in the gulf of paria, at carupano, at cariaco, and at cumana, render the accuracy of that opinion doubtful. in new andalusia, as well as in chile and peru, the shocks follow the course of the shore, and extend but little inland. this circumstance, as we shall soon find, indicates an intimate connection between the causes which produce earthquakes and volcanic eruptions. if the earth was most agitated on the coasts, because they are the lowest part of the land, why should not the oscillations be equally strong and frequent on those vast savannahs or prairies,* which are scarcely eight or ten toises above the level of the ocean? (* the llanos of cumana, of new barcelona, of calabozo, of apure, and of meta.) the earthquakes of cumana are connected with those of the west india islands; and it has even been suspected that they have some connection with the volcanic phenomena of the cordilleras of the andes. on the th of february , the soil of the province of quito suffered such a destructive commotion, that near , natives perished. at the same period the inhabitants of the eastern antilles were alarmed by shocks, which continued during eight months, when the volcano of guadaloupe threw out pumice-stones, ashes, and gusts of sulphureous vapours. the eruption of the th of september, during which very long-continued subterranean noises were heard, was followed on the th of december by the great earthquake of cumana. another volcano of the west india islands, that of st. vincent, affords an example of these extraordinary connections. this volcano had not emitted flames since , when they burst forth anew in . the total ruin of the city of caracas preceded this explosion thirty-five days, and violent oscillations of the ground were felt both in the islands and on the coasts of terra firma. it has long been remarked that the effects of great earthquakes extend much farther than the phenomena arising from burning volcanoes. in studying the physical revolutions of italy, in carefully examining the series of the eruptions of vesuvius and etna, we can scarcely recognise, notwithstanding the proximity of these mountains, any traces of a simultaneous action. it is on the contrary beyond a doubt, that at the period of the last and preceding destruction of lisbon,* the sea was violently agitated even as far as the new world, for instance, at the island of barbados, more than twelve hundred leagues distant from the coasts of portugal. (* destruction of lisbon: the st of november, , and st of march, . during the first of these earthquakes, the sea inundated, in europe, the coasts of sweden, england, and spain; in america, the islands of antigua, barbados, and martinique. at barbados, where the ordinary tides rise only from twenty-four to twenty-eight inches, the water rose twenty feet in carlisle bay. it became at the same time as black as ink; being, without doubt, mixed with the petroleum, or asphaltum, which abounds at the bottom of the sea, as well on the coasts of the gulf of cariaco, as near the island of trinidad. in the west indies, and in several lakes of switzerland, this extraordinary motion of the waters was observed six hours after the first shock that was felt at lisbon--philosophical transactions volume pages , , , ; ibid. volume page . at cadiz a mountain of water sixty feet high was seen eight miles distant at sea. this mass threw itself impetuously on the coasts, and beat down a great number of houses; like the wave eighty-four feet high, which on the th of june, , at the time of the great earthquake of lima, covered the port of callao.--acosta hist. natural de las indias edition de page . in north america, on lake ontario, violent agitations of the water were observed from the month of october . these phenomena are proofs of subterraneous communications at enormous distances. on comparing the periods of the great catastrophes of lima and guatimala, which generally succeed each other at long intervals, it has sometimes been thought, that the effect of an action slowly propagating along the cordilleras, sometimes from north to south, at other times from south to north, may be perceived.--cosmo bueno descripcion del peru ed. de lima page . four of these remarkable catastrophes, with their dates, may be here enumerated.) table of four catastrophes: column : mexico. (latitude degrees minutes north.) column : peru. (latitude degrees minutes south.) th of november, : th of june, . th of march, : th of june, . th of february, : th of october, . th of september, : th of february, . when the shocks are not simultaneous, or do not follow each other at short intervals, great doubts may be entertained with respect to the supposed communication of the movement.) several facts tend to prove that the causes which produce earthquakes have a near connection with those which act in volcanic eruptions. the connection of these causes was known to the ancients, and it excited fresh attention at the period of the discovery of america. the discovery of the new world not only offered new productions to the curiosity of man, it also extended the then existing stock of knowledge respecting physical geography, the varieties of the human species, and the migrations of nations. it is impossible to read the narratives of early spanish travellers, especially that of the jesuit acosta, without perceiving the influence which the aspect of a great continent, the study of extraordinary appearances of nature, and intercourse with men of different races, must have exercised on the progress of knowledge in europe. the germ of a great number of physical truths is found in the works of the sixteenth century; and that germ would have fructified, had it not been crushed by fanaticism and superstition. we learned, at pasto, that the column of black and thick smoke, which, in , issued for several months from the volcano near that shore, disappeared at the very hour, when, sixty leagues to the south, the towns of riobamba, hambato, and tacunga were destroyed by an enormous shock. in the interior of a burning crater, near those hillocks formed by ejections of scoriae and ashes, the motion of the ground is felt several seconds before each partial eruption takes place. we observed this phenomenon at vesuvius in , while the mountain threw out incandescent scoriae; we were witnesses of it in , on the brink of the immense crater of pichincha, from which, nevertheless, at that time, clouds of sulphureous acid vapours only issued. everything in earthquakes seems to indicate the action of elastic fluids seeking an outlet to diffuse themselves in the atmosphere. often, on the coasts of the pacific, the action is almost instantaneously communicated from chile to the gulf of guayaquil, a distance of six hundred leagues; and, what is very remarkable, the shocks appear to be the stronger in proportion as the country is distant from burning volcanoes. the granitic mountains of calabria, covered with very recent breccias, the calcareous chain of the apennines, the country of pignerol, the coasts of portugal and greece, those of peru and terra firma, afford striking proofs of this fact. the globe, it may be said, is agitated with the greater force, in proportion as the surface has a smaller number of funnels communicating with the caverns of the interior. at naples and at messina, at the foot of cotopaxi and of tunguragua, earthquakes are dreaded only when vapours and flames do not issue from the craters. in the kingdom of quito, the great catastrophe of riobamba led several well-informed persons to think that that country would be less frequently disturbed, if the subterranean fire should break the porphyritic dome of chimborazo; and if that colossal mountain should become a burning volcano. at all times analogous facts have led to the same hypotheses. the greeks, who, like ourselves, attributed the oscillations of the ground to the tension of elastic fluids, cited in favour of their opinion, the total cessation of the shocks at the island of euboea, by the opening of a crevice in the lelantine plain.* (* "the shocks ceased only when a crevice, which ejected a river of fiery mud, opened in the plain of lelantum, near chalcis."--strabo.) the phenomena of volcanoes, and those of earthquakes, have been considered of late as the effects of voltaic electricity, developed by a particular disposition of heterogeneous strata. it cannot be denied, that often, when violent shocks succeed each other within the space of a few hours, the electricity of the air sensibly increases at the instant the ground is most agitated; but to explain this phenomenon, it is unnecessary to recur to an hypothesis, which is in direct contradiction to everything hitherto observed respecting the structure of our planet, and the disposition of its strata. chapter . . peninsula of araya. salt-marshes. ruins of the castle of santiago. the first weeks of our abode at cumana were employed in testing our instruments, in herborizing in the neighbouring plains, and in examining the traces of the earthquake of the th of december, . overpowered at once by a great number of objects, we were somewhat embarrassed how to lay down a regular plan of study and observation. whilst every surrounding object was fitted to inspire in us the most lively interest, our physical and astronomical instruments in their turns excited strongly the curiosity of the inhabitants. we had numerous visitors; and in our desire to satisfy persons who appeared so happy to see the spots of the moon through dollond's telescope, the absorption of two gases in a eudiometrical tube, or the effects of galvanism on the motions of a frog, we were obliged to answer questions often obscure, and to repeat for whole hours the same experiments. these scenes were renewed for the space of five years, whenever we took up our abode in a place where it was understood that we were in possession of microscopes, telescopes, and electrical apparatus. i could not begin a regular course of astronomical observations before the th of july, though it was highly important for me to know the longitude given by berthoud's time-keeper; but it happened, that in a country where the sky is constantly clear and serene, no stars appeared for several nights. the whole series of the observations i made in and give for their results, that the latitude of the great square at cumana is degrees minutes seconds, and its longitude degrees minutes seconds. this longitude is founded on the difference of time, on lunar distances, on the eclipse of the sun (on the th of october, ), and on ten immersions of jupiter's satellites, compared with observations made in europe. the oldest chart we have of the continent, that of don diego ribeiro, geographer to the emperor charles the fifth, places cumana in latitude degrees minutes; which differs fifty-eight minutes from the real latitude, and half a degree from that marked by jefferies in his american pilot, published in . during three centuries the whole of the coast of terra firma has been laid down too far to the south: this has been owing to the current near the island of trinidad, which sets toward the north, and mariners are led by their dead-reckoning to think themselves farther south than they really are. on the th of august a halo round the moon fixed the attention of the inhabitants of cumana, who considered it as the presage of some violent earthquake; for, according to popular notions, all extraordinary phenomena are immediately connected with each other. coloured circles around the moon are much more rare in northern countries than in provence, italy, and spain. they are seen particularly (and this fact is singular enough) when the sky is clear, and the weather seems to be most fair and settled. under the torrid zone beautiful prismatic colours appear almost every night, and even at the time of the greatest droughts; often in the space of a few minutes they disappear several times, because, doubtless, the superior currents change the state of the floating vapours, by which the light is refracted. i sometimes even observed, between the fifteenth degree of latitude and the equator, small halos around the planet venus; the purple, orange, and violet, were distinctly perceived: but i never saw any colours around sirius, canopus, or acherner. while the halo was visible at cumana, the hygrometer denoted great humidity; nevertheless the vapours appeared so perfectly in solution, or rather so elastic and uniformly disseminated, that they did not alter the transparency of the atmosphere. the moon arose after a storm of rain, behind the castle of san antonio. as soon as she appeared on the horizon, we distinguished two circles: one large and whitish, forty-four degrees in diameter; the other a small circle of degree minutes, displaying all the colours of the rainbow. the space between the two circles was of the deepest azure. at four degrees height, they disappeared, while the meteorological instruments indicated not the slightest change in the lower regions of the air. this phenomenon had nothing extraordinary, except the great brilliancy of the colours, added to the circumstance, that, according to the measures taken with ramsden's sextant, the lunar disk was not exactly in the centre of the haloes. without this actual measurement we might have thought that the excentricity was the effect of the projection of the circles on the apparent concavity of the sky. if the situation of our house at cumana was highly favourable for the observation of the stars and meteorological phenomena, it obliged us to be sometimes the witnesses of painful scenes during the day. a part of the great square is surrounded with arcades, above which is one of those long wooden galleries, common in warm countries. this was the place where slaves, brought from the coast of africa, were sold. of all the european governments denmark was the first, and for a long time the only power, which abolished the traffic; yet notwithstanding that fact, the first negroes we saw exposed for sale had been landed from a danish slave-ship. what are the duties of humanity, national honour, or the laws of their country, to men stimulated by the speculations of sordid interest? the slaves exposed to sale were young men from fifteen to twenty years of age. every morning cocoa-nut oil was distributed among them, with which they rubbed their bodies, to give their skin a black polish. the persons who came to purchase examined the teeth of these slaves, to judge of their age and health; forcing open their mouths as we do those of horses in a market. this odious custom dates from africa, as is proved by the faithful pictures drawn by the inimitable cervantes,* who after his long captivity among the moors, described the sale of christian slaves at algiers. (* el trato de argel. jorn. viage al parnasso page .) it is distressing to think that even at this day there exist european colonists in the west indies who mark their slaves with a hot iron, to know them again if they escape. this is the treatment bestowed on those "who save other men the labour of sowing, tilling, and reaping."* (* la bruyere caracteres edition chapter page . i will here cite a passage strongly characteristic of la bruyere's benevolent feeling for his fellow-creatures. "we find (under the torrid zone) certain wild animals, male and female, scattered through the country, black, livid, and all over scorched by the sun, bent to the earth which they dig and turn up with invincible perseverance. they have something like articulate utterance; and when they stand up on their feet, they exhibit a human face, and in fact these creatures are men.") in the number of slaves did not exceed six thousand in the two provinces of cumana and barcelona, when at the same period the whole population was estimated at one hundred and ten thousand inhabitants. the trade in african slaves, which the laws of the spaniards have never favoured, is almost as nothing on these coasts where the trade in american slaves was carried on in the sixteenth century with desolating activity. macarapan, anciently called amaracapana, cumana, araya, and particularly new cadiz, built on the islet of cubagua, might then be considered as commercial establishments for facilitating the slave trade. girolamo benzoni of milan, who at the age of twenty-two visited terra firma, took part in some expeditions in to the coasts of bordones, cariaco, and paria, to carry off the unfortunate natives, he relates with simplicity, and often with a sensibility not common in the historians of that time, the examples of cruelty of which he was a witness. he saw the slaves dragged to new cadiz, to be marked on the forehead and on the arms, and for the payment of the quint to the officers of the crown. from this port the indians were sent to the island of haiti or st. domingo, after having often changed masters, not by way of sale, but because the soldiers played for them at dice. the first excursion we made was to the peninsula of araya, and those countries formerly celebrated for the slave-trade and the pearl-fishery. we embarked on the rio manzanares, near the indian suburb, on the th of august, about two in the morning. the principal objects of this excursion were, to see the ruins of the castle of araya, to examine the salt-works, and to make a few geological observations on the mountains forming the narrow peninsula of maniquarez. the night was delightfully cool; swarms of phosphorescent insects* glistened in the air (* elater noctilucus. ), and over a soil covered with sesuvium, and groves of mimosa which bordered the river. we know how common the glow-worm* (* lampyris italica, l. noctiluca.) is in italy and in all the south of europe, but the picturesque effect it produces cannot be compared to those innumerable, scattered, and moving lights, which embellish the nights of the torrid zone, and seem to repeat on the earth, along the vast extent of the savannahs, the brilliancy of the starry vault of heaven. when, on descending the river, we drew near plantations, or charas, we saw bonfires kindled by the negroes. a light and undulating smoke rose to the tops of the palm-trees, and imparted a reddish hue to the disk of the moon. it was on a sunday night, and the slaves were dancing to the music of the guitar. the people of africa, of negro race, are endowed with an inexhaustible store of activity and gaiety. after having ended the labours of the week, the slaves, on festival days, prefer to listless sleep the recreations of music and dancing. the bark in which we passed the gulf of cariaco was very spacious. large skins of the jaguar, or american tiger, were spread for our repose during the night. though we had yet scarcely been two months in the torrid zone, we had already become so sensible to the smallest variation of temperature that the cold prevented us from sleeping; while, to our surprise, we saw that the centigrade thermometer was as high as . degrees. this fact is familiar to those who have lived long in the indies, and is worthy the attention of physiologists. bouguer relates, that when he reached the summit of montagne pelee, in the island of martinique, he and his companions shivered with cold, though the heat was above . degrees. in reading the interesting narrative of captain bligh, who, in consequence of a mutiny on board the bounty, was forced to make a voyage of twelve hundred leagues in an open boat, we find that that navigator, in the tenth and twelfth degrees of south latitude, suffered much more from cold than from hunger. during our abode at guayaquil, in the month of january , we observed that the natives covered themselves, and complained of the cold, when the thermometer sank to . degrees, whilst they felt the heat suffocating at . degrees. six or seven degrees were sufficient to cause the opposite sensations of cold and heat; because, on these coasts of south america, the ordinary temperature of the atmosphere is twenty-eight degrees. the humidity, which modifies the conducting power of the air for heat, contributes greatly to these impressions. in the port of guayaquil, as everywhere else in the low regions of the torrid zone, the weather grows cool only after storms of rain: and i have observed that when the thermometer sinks to . degrees, de luc's hygrometer keeps up to fifty and fifty-two degrees; it is, on the contrary, at thirty-seven degrees in a temperature of . degrees. at cumana, during very heavy showers, people in the streets are heard exclaiming, que hielo! estoy emparamado;* though the thermometer exposed to the rain sinks only to . degrees. (* "what an icy cold! i shiver as if i was on the top of the mountains." the provincial word emparamarse can be translated only by a very long periphrasis. paramo, in peruvian puna, is a denomination found on all the maps of spanish america. in the colonies it signifies neither a desert nor a heath, but a mountainous place covered with stunted trees, exposed to the winds, and in which a damp cold perpetually reigns. in the torrid zone, the paramos are generally from one thousand six hundred to two thousand toises high. snow often falls on them, but it remains only a few hours; for we must not confound, as geographers often do, the words paramo and puna with that of nevado, in peruvian ritticapa, a mountain which enters into the limits of perpetual snow. these notions are highly interesting to geology and the geography of plants; because, in countries where no height has been measured, we may form an exact idea of the lowest height to which the cordilleras rise, on looking into the map for the words paramo and nevado. as the paramos are almost continually enveloped in a cold and thick fog, the people say at santa fe and at mexico, cae un paramito when a thick small rain falls, and the temperature of the air sinks considerably. from paramo has been made emparamarse, which signifies to be as cold as if we were on the ridge of the andes.) from these observations it follows, that between the tropics, in plains where the temperature of the air is in the day-time almost invariably above twenty-seven degrees, warmer clothing during the night is requisite, whenever in a damp air the thermometer sinks four or five degrees. we landed about eight in the morning at the point of araya, near the new salt-works. a solitary house, near a battery of three guns, the only defence of this coast, since the destruction of the fort of santiago, is the abode of the inspector. it is surprising that these salt-works, which formerly excited the jealousy of the english, dutch, and other maritime powers, have not created a village, or even a farm; a few huts only of poor indian fishermen are found at the extremity of the point of araya. this spot commands a view of the islet of cubagua, the lofty hills of margareta, the ruins of the castle of santiago, the cerro de la vela, and the calcareous chain of the brigantine, which bounds the horizon towards the south. i availed myself of this view to take the angles between these different points, from a basis of four hundred toises, which i measured between the battery and the hill called the pena. as the cerro de la vela, the brigantine, and the castle of san antonio at cumana, are equally visible from the punta arenas, situated to the west of the village of maniquarez, the same objects were available for an approximate determination of the respective positions of several points, which are laid down in the mineralogical chart of the peninsula of araya. the abundance of salt contained in the peninsula of araya was known to alonzo nino, when, following the tracks of columbus, ojeda, and amerigo vespucci, he visited these countries in . though of all the people on the globe the natives of south america consume the least salt, because they scarcely eat anything but vegetables, it nevertheless appears, that at an early period the guayquerias dug into the clayey and muriatiferous soil of punta arenas. even the brine-pits, now called new, (la salina nueva,) situated at the extremity of cape araya, were worked in very remote times. the spaniards, who settled at first at cubagua, and soon after on the coasts of cumana, worked, from the beginning of the sixteenth century, the salt marshes which stretch away like a lagoon to the north of cerro de la vela. as at that period the peninsula of araya had no settled population, the dutch availed themselves of the natural riches of a soil which appeared to be property common to all nations. in our days, each colony has its own salt-works, and navigation is so much improved, that the merchants of cadiz can send, at a small expense, salt from spain and portugal to the southern hemisphere, a distance of leagues, to cure meat at monte video and buenos ayres. these advantages were unknown at the time of the conquest; colonial industry had then made so little progress, that the salt of araya was carried, at great expense, to the west india islands, carthagena, and portobello. in , the court of madrid sent armed ships to punta araya, with orders to expel the dutch by force of arms. the dutch, however, continued to carry on a contraband trade in salt till, in , there was built near the salt-works a fort, which afterwards became celebrated under the name of the castillo de santiago, or the real fuerza de araya. the great salt-marshes are laid down on the oldest spanish maps, sometimes as a bay, and at other times as a lagoon. laet, who wrote his orbis novus in , and who had some excellent notions respecting these coasts, expressly states, that the lagoon was separated from the sea by an isthmus above the level of high water. in , an impetuous hurricane destroyed the salt-works of araya, and rendered the fort, the construction of which had cost more than a million of piastres, useless. this hurricane was a very rare phenomenon in these regions, where the sea is in general as calm as the water in our large rivers. the waves overflowed the land to a great extent; and by the effect of this eruption of the ocean the salt lake was converted into a gulf several miles in length. since that period, artificial reservoirs, or pits, (vasets,) have been formed, to the north of the range of hills which separates the castle from the north coast of the peninsula. the consumption of salt amounted, in and , in the two provinces of cumana* and barcelona, to nine or ten thousand fanegas, each sixteen arrobas, or four hundredweight. this consumption is very considerable, and gives, if we deduct from the total population fifty thousand indians, who eat very little salt, sixty pounds for each person. salt beef, called tasajo, is the most important article of export from barcelona. of nine or ten thousand fanegas furnished by the two provinces conjointly, three thousand only are produced by the salt-works of araya; the rest is extracted from the sea-water at the morro of barcelona, at pozuelos, at piritu, and in the golfo triste. in mexico, the salt lake of penon blanco alone furnishes yearly more than two hundred and fifty thousand fanegas of unpurified salt. (* at the period of my visit to that country the government of cumana comprehended the two provinces of new andalusia and new barcelona. the words province and govierno, or government of cumana, are consequently not synonymous. a catalonian, juan de urpin, who had been by turns a canon, a doctor of laws, a counsellor in st. domingo, and a private soldier in the castle of araya, founded in , the city of new barcelona, and attempted to give the name of new catalonia (nueva cathaluna) to the province of which this newly constructed city became the capital. this attempt was fruitless; and it is from the capital that the whole province took its name. since my departure from america, it has been raised to the rank of a govierno. in new andalusia, the indian name of cumana has superseded the names nueva toledo and nueva cordoba, which we find on the maps of the seventeenth century.) the province of caracas possesses fine salt-works at los roques; those which formerly existed at the small island of tortuga, where the soil is strongly impregnated with muriate of soda, were destroyed by order of the spanish government. a canal was made by which the sea has free access to the salt-marshes. foreign nations who have colonies in the west indies frequented this uninhabited island; and the court of madrid, from views of suspicious policy, was apprehensive that the salt-works of tortuga would give rise to settlements, by means of which an illicit trade would be carried on with terra firma. the royal administration of the salt-works of araya dates only from the year . before that period they were in the hands of indian fishermen, who manufactured salt at their pleasure, and sold it, paying the government the moderate sum of three hundred piastres. the price of the fanega was then four reals;* (* in this narrative, as well as in the political essay on new spain, all the prices are reckoned in piastres, and silver reals (reales de plata). eight of these reals are equivalent to a piastre, or one hundred and five sous, french money ( shillings / pence english). nouv. esp. volume pages , and .) but the salt was extremely impure, grey, mixed with earthy particles, and surcharged with muriate and sulphate of magnesia. since the province of cumana has become dependent on the intendancia of caracas, the sale of salt is under the control of the excise; and the fanega, which the guayquerias sold at half a piastre, costs a piastre and a half.* (* the fanega of salt is sold to those indians and fishermen who do not pay the duties (derechos reales), at punta araya for six, at cumana for eight reals. the prices to the other tribes are, at araya ten, at cumana twelve reals.) this augmentation of price is slightly compensated by greater purity of the salt, and by the facility with which the fishermen and farmers can procure it in abundance during the whole year. the salt-works of araya yielded to the treasury, in , a clear income of eight thousand piastres. considered as a branch of industry the salt produced here is not of any great importance, but the nature of the soil which contains the salt-marshes is well worthy of attention. in order to obtain a clear idea of the geological connection existing between this muriatiferous soil and the rocks of more ancient formation, we shall take a general view of the neighbouring mountains of cumana, and those of the peninsula of araya, and the island of margareta. three great parallel chains extend from east to west. the two most northerly chains are primitive, and contain the mica-slates of macanao, and the san juan valley, of maniquarez, and of chuparipari. these we shall distinguish by the names of cordillera of the island of margareta, and cordillera of araya. the third chain, the most southerly of the whole, the cordillera of the brigantine and of the cocollar, contains rocks only of secondary formation; and, what is remarkable enough, though analogous to the geological constitution of the alps westward of st. gothard, the primitive chain is much less elevated than that which was composed of secondary rocks.* (* in new andalusia, the cordillera of the cocollar nowhere contains primitive rocks. if these rocks form the nucleus of this chain, and rise above the level of the neighbouring plains, which is scarcely probable, we must suppose that they are all covered with limestone and sandstone. in the swiss alps, on the contrary, the chain which is designated under the too vague denomination of lateral and calcareous, contains primitive rocks, which, according to the observations of escher and leopold von buch, are often visible to the height of eight hundred or a thousand toises.) the sea has separated the two northern cordilleras, those of the island of margareta and the peninsula of araya; and the small islands of coche and of cubagua are remnants of the land that was submerged. farther to the south, the vast gulf cariaco stretches away, like a longitudinal valley formed by the irruption of the sea, between the two small chains of araya and the cocollar, between the mica-slate and the alpine limestone. we shall soon see that the direction of the strata, very regular in the first of these rocks, is not quite parallel with the general direction of the gulf. in the high alps of europe, the great longitudinal valley of the rhone also sometimes cuts at an oblique angle the calcareous banks in which it has been excavated. the two parallel chains of araya and the cocollar were connected, to the east of the town of cariaco, between the lakes of campoma and putaquao, by a kind of transverse dyke, which bears the name of cerro de meapire, and which in distant times, by resisting the impulse of the waves, has hindered the waters of the gulf of cariaco from uniting with those of the gulf of paria. thus, in switzerland, the central chain, that which passes by the col de ferrex, the simplon, st. gothard, and the splugen, is connected on the north and the south with two lateral chains, by the mountains of furca and maloya. it is interesting to recall to mind those striking analogies exhibited in both continents by the external structure of the globe. the primitive chain of araya ends abruptly in the meridian of the village of maniquarez; and the western slope of the peninsula, as well as the plains in the midst of which stands the castle of san antonio, is covered with very recent formations of sandstone and clay mixed with gypsum. near maniquarez, breccia or sandstone with calcareous cement, which might easily be confounded with real limestone, lies immediately over the mica-slate; while on the opposite side, near punta delgada, this sandstone covers a compact bluish grey limestone, almost destitute of petrifactions, and traversed by small veins of calcareous spar. this last rock is analogous to the limestone of the high alps.* (* alpenkalkstein.) the very recent sandstone formation of the peninsula of araya contains:--first, near punta arenas, a stratified sandstone, composed of very fine grains, united by a calcareous cement in small quantity;--secondly, at the cerro de la vela, a schistose sandstone,* (* sandsteinschiefer.) without mica, and passing into slate-clay,* (* thonschiefer.) which accompanies coal;--thirdly, on the western side, between punta gorda and the ruins of the castle of santiago, breccia composed of petrified sea-shells united by a calcareous cement, in which are mingled grains of quartz;--fourthly, near the point of barigon, whence the stone employed for building at cumana is obtained, banks of yellowish white shelly limestone, in which are found some scattered grains of quartz;--fifthly, at penas negras, at the top of the cerro de la vela, a bluish grey compact limestone, very tender, almost without petrifactions, and covering the schistose sandstone. however extraordinary this mixture of sandstone and compact limestone* (* dichter kalkstein.) may appear, we cannot doubt that these strata belong to one and the same formation. the very recent secondary rocks everywhere present analogous phenomena; the molasse of the pays de vaud contains a fetid shelly limestone, and the cerite limestone of the banks of the seine is sometimes mixed with sandstone. the strata of calcareous breccia are composed of an infinite number of sea-shells, from four to six inches in diameter, and in part well preserved. we find they contain not ammonites, but ampullaires, solens, and terebratulae. the greater part of these shells are mixed: the oysters and pectinites being sometimes arranged in families. the whole are easily detached, and their interior is filled with fossil madrepores and cellepores. we have now to speak of a fourth formation, which probably rests* on the calcareous sandstone of araya, i mean the muriatiferous clay. (* it were to be wished that mineralogical travellers would examine more particularly the cerro de la vela. the limestone of the penas negras rests on a slate-clay, mixed with quartzose sand; but there is no proof of the muriatiferous clay of the salt-works being of more ancient formation than this slate-clay, or of its alternating with banks of sandstone. no well having been dug in these countries, we can have no information respecting the superposition of the strata. the banks of calcareous sandstone, which are found at the mouth of the salt lake, and near the fishermen's huts on the coast opposite cape macano, appeared to me to lie beneath the muriatiferous clay.) this clay, hardened, impregnated with petroleum, and mixed with lamellar and lenticular gypsum, is analogous to the salzthon, which in europe accompanies the sal-gem of berchtesgaden, and in south america that of zipaquira. it is generally of a smoke-grey colour, earthy, and friable; but it encloses more solid masses of a blackish brown, of a schistose, and sometimes conchoidal fracture. these fragments, from six to eight inches long, have an angular form. when they are very small, they give the clay a porphyroidal appearance. we find disseminated in it, as we have already observed, either in nests or in small veins, selenite, and sometimes, though seldom, fibrous gypsum. it is remarkable enough, that this stratum of clay, as well as the banks of pure sal-gem and the salzthon in europe, scarcely ever contains shells, while the rocks adjacent exhibit them in great abundance. although the muriate of soda is not found visible to the eye in the clay of araya, we cannot doubt of its existence. it shows itself in large crystals, if we sprinkle the mass with rain-water and expose it to the sun. the lagoon to the east of the castle of santiago exhibits all the phenomena which have been observed in the salt lakes of siberia, described by lepechin, gmelin, and pallas. this lagoon receives, however, only the rain-waters, which filter through the banks of clay, and unite at the lowest point of the peninsula. while the lagoon served as a salt-work to the spaniards and the dutch, it did not communicate with the sea; at present this communication has been interrupted anew, by faggots placed at the place where the waters of the ocean made an irruption in . after great droughts, crystallized and very pure muriate of soda, in masses of three or four cubic feet, is still drawn from time to time from the bottom of the lagoon. the salt waters of the lake, exposed to the heat of the sun, evaporate at their surface; crusts of salt, formed in a saturated solution, fall to the bottom; and by the attraction between crystals of a similar nature and form, the crystallized masses daily augment. it is generally observed that the water is brackish wherever lagoons are formed in clayey ground. it is true, that for the new salt-work near the battery of araya, the seawater is received into pits, as in the salt marshes of the south of france; but in the island of margareta, near pampatar, salt is manufactured by employing only fresh water, with which the muriatiferous clay has first been lixiviated. we must not confound the salt disseminated in these clayey soils with that contained in the sands of the seashore, on the coasts of normandy. these phenomena, considered in a geognostical point of view, have scarcely any properties in common. i have seen muriatiferous clay at the level of the ocean at punta araya, and at two thousand toises' height in the cordilleras of new grenada. if in the former of these places it lies on very recent shelly breccia, it forms, on the contrary, in austria near ischel, a considerable stratum in the alpine limestone, which, though equally posterior to the existence of organic life on the globe, is nevertheless of high antiquity, as is proved by the great number of rocks with which it is covered. we shall not question, that sal-gem, either pure or mixed with muriatiferous clay, may have been deposited by an ancient sea; but everything evinces that it was formed during an order of things bearing no resemblance to that in which the sea at present, by a slower operation, deposits a few particles of muriate of soda on the sands of our shores. in the same manner as sulphur and coal belong to periods of formation very remote from each other, the sal-gem is also found sometimes in transition gypsum,* (* uebergangsgyps, in the transition slate of white alley (l'allee blanche), and between the grauwacke and black transition limestone near bex, below the dent de chamossaire, according to m. von buch.) sometimes in the alpine limestone,* (* at halle in the tyrol.) sometimes in a muriatiferous clay lying on a very recent sandstone,* (* at punta araya.) and lastly, sometimes in a gypsum* posterior to the chalk. (* gypsum of the third formation among the secondary gypsums. the first formation contains the gypsum in which are found the brine-springs of thuringia, and which is placed either in the alpine limestone or zechstein, to which it essentially belongs (freiesleben geognost. arbeiten tome page ), or between the zechstein and the limestone of the jura, or between the zechstein and the new sandstone. it is the ancient gypsum of secondary formation of werner's school (alterer flozgyps), which we almost preferably call muriatiferous gypsum. the second formation is composed of fibrous gypsum, placed either in the molasse or new sandstone, or between this and the upper limestone. it abounds in common clay, which differs essentially from the salzthon or muriatiferous clay. the third formation of gypsum is more recent than chalk. to this belongs the bony gypsum of paris; and, as appears from the researches of mr. steffens (geogn. aufsatsze page ), the gypsum of segeberg, in holstein, in which sal-gem is sometimes disseminated in very small nests (jenaische litteratur-zeitung page ). the gypsum of paris, lying between a cerite limestone, which covers chalk and a sandstone without shells, is distinguished by fossil bones of quadrupeds, while the segeberg and lunebourg gypsums, the position of which is more uncertain, are characterized by the boracits which they contain. two other formations, far anterior to the three we have just mentioned, are the transition gypsum (ubergangsgyps) of aigle, and the primitive gypsum (urgyps) of the valley of canaria, near airolo. i flatter myself that i may render some service to those geologists who prefer the knowledge of positive facts to speculation on the origin of things, by furnishing them with materials from which they may generalize their ideas on the formation of rocks in both hemispheres. the relative antiquity of the formations is the principal object of a science which is to render us acquainted with the structure of the globe; that is to say, the nature of the strata which constitute the crust of our planet.) the new salt-works of araya have five reservoirs, or pits, the largest of which have two thousand three hundred square toises surface. their mean depth is eight inches. use is made both of the rain-water, which by filtration collects at the lowest part of the plain, and of the water of the sea, which enters by canals, or martellieres, when the flood-tide is favoured by the winds. the situation of these new salt-works is less advantageous than that of the lagoon. the waters which fall into the latter pass over steeper slopes, washing a greater extent of ground. the earth already lixiviated is never carried away here, as it is from time to time in the island of margareta; nor have wells been dug in the muriatiferous clay, with the view of finding strata richer in muriate of soda. the salineros, or salt-workers generally complain of want of rain; and in the new salt-works, it appears to me difficult to determine what quantity of salt is derived solely from the waters of the sea. the natives estimate it at a sixth of the total produce. the evaporation is extremely strong, and favoured by the constant motion of the air; so that the salt is collected in eighteen or twenty days after the pits are filled. though the muriate of soda is manufactured with less care in the peninsula of araya than at the salt-works of europe, it is nevertheless purer, and contains less of earthy muriates and sulphates. we know not whether this purity may be attributed to that portion of the salt which is furnished by the sea; for though it is extremely probable, that the quantity of salt dissolved in the waters of the ocean is nearly the same under every zone, it is not less uncertain whether the proportion between the muriate of soda, the muriate and sulphate of magnesia, and the sulphate and carbonate of lime, be equally invariable. having examined the salt-works, and terminated our geodesical operations, we departed at the decline of day to sleep at an indian hut, some miles distant, near the ruins of the castle of araya. directing our course southward, we traversed first the plain covered with muriatiferous clay, and stripped of vegetation; then two chains of hills of sandstone, between which the lagoon is situated. night overtook us while we were in a narrow path, bordered on one side by the sea, and on the other by a range of perpendicular rocks. the tide was rising rapidly, and narrowed the road at every step. we at length arrived at the foot of the old castle of araya, where we enjoyed a prospect that had in it something lugubrious and romantic. the ruins stand on a bare and arid mountain, crowned with agave, columnar cactus, and thorny mimosas: they bear less resemblance to the works of man, than to those masses of rock which were ruptured at the early revolutions of the globe. we were desirous of stopping to admire this majestic spectacle, and to observe the setting of venus, whose disk appeared at intervals between the yawning crannies of the castle; but the muleteer, who served as our guide, was parched with thirst, and pressed us earnestly to return. he had long perceived that we had lost our way; and as he hoped to work on our fears he continually warned us of the danger of tigers and rattlesnakes. venomous reptiles are, indeed, very common near the castle of araya; and two jaguars had been lately killed at the entrance of the village of maniquarez. if we might judge from their skins, which were preserved, their size was not less than that of the indian tiger. we vainly represented to our guide that those animals did not attack men where the goats furnished them with abundant prey; we were obliged to yield, and return. after having proceeded three quarters of an hour along a shore covered by the tide we were joined by the negro, who carried our provision. uneasy at not seeing us arrive, he had come to meet us, and he led us through a wood of nopals to a hut inhabited by an indian family. we were received with the cordial hospitality observed in this country among people of every tribe. the hut in which we slung our hammocks was very clean; and there we found fish, plantains, and what in the torrid zone is preferable to the most sumptuous food, excellent water. the next day at sunrise we found that the hut in which we had passed the night formed part of a group of small dwellings on the borders of the salt lake, the remains of a considerable village which had formerly stood near the castle. the ruins of a church were seen partly buried in the sand, and covered with brushwood. when, in , to save the expense of the garrison, the castle of araya was totally dismantled, the indians and mulattoes who were settled in the neighbourhood emigrated by degrees to maniquarez, to cariaco, and in the suburb of the guayquerias at cumana. a small number, bound from affection to their native soil, remained in this wild and barren spot. these poor people live by catching fish, which are extremely abundant on the coast and the neighbouring shoals. they appear satisfied with their condition, and think it strange when they are asked why they have no gardens or culinary vegetables. our gardens, they reply, are beyond the gulf; when we carry our fish to cumana, we bring back plantains, cocoa-nuts, and cassava. this system of economy, which favours idleness, is followed at maniquarez, and throughout the whole peninsula of araya. the chief wealth of the inhabitants consists in goats, which are of a very large and very fine breed, and rove in the fields like those at the peak of teneriffe. they have become entirely wild, and are marked like the mules, because it would be difficult to recognize them from their colour or the arrangement of their spots. these wild goats are of a brownish yellow, and are not varied in colour like domestic animals. if in hunting, a colonist kills a goat which he does not consider as his own property, he carries it immediately to the neighbour to whom it belongs. during two days we heard it everywhere spoken of as a very extraordinary circumstance, that an inhabitant of maniquarez had lost a goat, on which it was probable that a neighbouring family had regaled themselves. among the mulattoes, whose huts surround the salt lake, we found it shoemaker of castilian descent. he received us with the air of gravity and self-sufficiency which in those countries characterize almost all persons who are conscious of possessing some peculiar talent. he was employed in stretching the string of his bow, and sharpening his arrows to shoot birds. his trade of a shoemaker could not be very lucrative in a country where the greater part of the inhabitants go barefooted; and he only complained that, on account of the dearness of european gunpowder, a man of his quality was reduced to employ the same weapons as the indians. he was the sage of the plain; he understood the formation of the salt by the influence of the sun and full moon, the symptoms of earthquakes, the marks by which mines of gold and silver are discovered, and the medicinal plants, which, like all the other colonists from chile to california, he classified into hot and cold.* (* exciting or debilitating, the sthenic and asthenic, of brown's system.) having collected the traditions of the country, he gave us some curious accounts of the pearls of cubagua, objects of luxury, which he treated with the utmost contempt. to show us how familiar to him were the sacred writings he took a pride in reminding us that job preferred wisdom to all the pearls of the indies. his philosophy was circumscribed to the narrow circle of the wants of life. the possession of a very strong ass, able to carry a heavy load of plantains to the embarcadero, was the consummation of all his wishes. after a long discourse on the emptiness of human greatness, he drew from a leathern pouch a few very small opaque pearls, which he forced us to accept, enjoining us at the same time to note on our tablets that a poor shoemaker of araya, but a white man, and of noble castilian race, had been enabled to give us something which, on the other side of the sea,* was sought for as very precious. (* 'por alla,' or, 'del otro lado del charco,' (properly 'beyond,' or 'on the other side of the great lake'), a figurative expression, by which the people in the spanish colonies denote europe.) i here acquit myself of the promise i made to this worthy man, who disinterestedly refused to accept of the slightest retribution. the pearl coast presents the same aspect of misery as the countries of gold and diamonds, choco and brazil; but misery is not there attended with that immoderate desire of gain which is excited by mineral wealth. the pearl-breeding oyster (avicula margaritifera, cuvier) abounds on the shoals which extend from cape paria to cape la vela. the islands of margareta, cubagua, coche, punta araya, and the mouth of the rio la hacha, were, in the sixteenth century, as celebrated as were the persian gulf and the island of taprobana among the ancients. it is incorrectly alleged by some historians that the natives of america were unacquainted with the luxury of pearls. the first spaniards who landed in terra firma found the savages decked with pearl necklaces and bracelets; and among the civilized people of mexico and peru, pearls of a beautiful form were extremely sought after. i have published a dissertation on the statue of a mexican priestess in basalt, whose head-dress, resembling the calantica of the heads of isis, is ornamented with pearls. las casas and benzoni have described, but not without some exaggeration, the cruelties which were exercised on the unhappy indian slaves and negroes employed in the pearl fishery. at the beginning of the conquest the island of coche alone furnished pearls amounting in value to fifteen hundred marks per month. the quint which the king's officers drew from the produce of pearls, amounted to fifteen thousand ducats; which, according to the value of the precious metals in those times, and the extensiveness of contraband trade, may be regarded as a very considerable sum. it appears that till the value of the pearls sent to europe amounted yearly on an average to more than eight hundred thousand piastres. in order to judge of the importance of this branch of commerce to seville, toledo, antwerp, and genoa, we should recollect that at the same period the whole of the mines of america did not furnish two millions of piastres; and that the fleet of ovando was thought to contain immense wealth, because it had on board nearly two thousand six hundred marks of silver. pearls were the more sought after, as the luxury of asia had been introduced into europe by two ways diametrically opposite: that of constantinople, where the palaeologi wore garments covered with strings of pearls; and that of grenada, the residence of the moorish kings, who displayed at their court all the luxury of the east. the pearls of the east were preferred to those of the west; but the number of the latter which circulated in commerce was nevertheless considerable at the period immediately following the discovery of america. in italy as well as in spain, the islet of cubagua became the object of numerous mercantile speculations. benzoni* relates the adventure of one luigi lampagnano, to whom charles the fifth granted the privilege of proceeding with five caravels to the coasts of cumana to fish for pearls. (* la hist. del mondo nuovo page . luigi lampagnano, a relation of the assassin of the duke of milan, galeazzo maria sforza, could not pay the merchants of seville who had advanced the money for his voyage; he remained five years at cubagua, and died in a fit of insanity.) the colonists sent him back with this bold message: "that the emperor was too liberal of what was not his own, and that he had no right to dispose of the oysters which live at the bottom of the sea." the pearl fishery diminished rapidly about the end of the sixteenth century; and, according to laet, it had long ceased in .* (* "insularum cubaguae et coches quondam magna fuit dignitas, quum unionum captura floreret: nunc, illa deficiente, obscura admodum fama." laet nova orbis page . this accurate compiler, speaking of punta araya, adds, this country is so forgotten, "ut vix ulla americae meridionalis pars hodie obscurior sit.") the industry of the venetians, who imitated fine pearls with great exactness, and the frequent use of cut diamonds,* rendered the fisheries of cubagua less lucrative. (* the cutting of diamonds was invented by lewis de berquen, in , but the art became common only in the following century.) at the same time, the oysters which yielded the pearls became scarcer, not, because, according to a popular tradition, they were frightened by the sound of the oars, and removed elsewhere; but because their propagation had been impeded by the imprudent destruction of the shells by thousands. the pearl-bearing oyster is of a more delicate nature than most of the other acephalous mollusca. at the island of ceylon, where, in the bay of condeatchy, the fishery employs six hundred divers, and where the annual produce is more than half a million of piastres, it has vainly been attempted to transplant the oysters to other parts of the coast. the government permits fishing there only during a single month; while at cubagua the bank of shells was fished at all seasons. to form an idea of the destruction of the species caused by the divers, we must remember that a boat sometimes collects, in two or three weeks, more than thirty-five thousand oysters. the animal lives but nine or ten years; and it is only in its fourth year that the pearls begin to show themselves. in ten thousand shells there is often not a single pearl of value. tradition records that on the bank of margareta the fishermen opened the shells one by one: in the island of ceylon the animals are thrown into heaps to rot in the air; and to separate the pearls which are not attached to the shell, the animal pulp is washed, as miners wash the sand which contains grains of gold, tin, or diamonds. at present spanish america furnishes no other pearls for trade than those of the gulf of panama, and the mouth of the rio de la hacha. on the shoals which surround cubagua, coche, and the island of margareta, the fishery is as much neglected as on the coasts of california.* (* i am astonished at never having heard, in the course of my travels, of pearls found in the fresh-water shells of south america, though several species of the unio genus abound in the rivers of peru.) it is believed at cumana, that the pearl-oyster has greatly multiplied after two centuries of repose; and in , some new attempts were made at margareta for the fishing of pearls. it has been asked, why the pearls found at present in shells which become entangled in the fishermen's nets are so small, and have so little brilliancy,* whilst, on the spaniards' arrival, they were extremely beautiful, though the indians doubtless had not taken the trouble of diving to collect them. (* the inhabitants of araya sometimes sell these small pearls to the retail dealers of cumana. the ordinary price is one piastre per dozen.) the problem is so much the more difficult to solve, as we know not whether earthquakes may have altered the nature of the bottom of the sea, or whether the changes of the submarine currents may have had an influence either on the temperature of the water, or on the abundance of certain mollusca on which the aronde feeds. on the morning of the th our host's son, a young and very robust indian, conducted us by the way of barigon and caney to the village of maniquarez, which was four hours' walk. from the effect of the reverberation of the sands, the thermometer kept up to . degrees. the cylindric cactus, which bordered the road, gave the landscape an appearance of verdure, without affording either coolness or shade. before our guide had walked a league, he began to sit down every moment, and at length he wished to repose under the shade of a fine tamarind tree near casas de la vela, to await the approach of night. this characteristic trait, which we observed every time we travelled with indians, has given rise to very erroneous ideas of the physical constitutions of the different races of men. the copper-coloured native, more accustomed to the burning heat of the climate, than the european traveller, complains more, because he is stimulated by no interest. money is without attraction for him; and if he permits himself to be tempted by gain for a moment, he repents of his resolution as soon as he is on the road. the same indian, who would complain, when in herborizing we loaded him with a box filled with plants, would row his canoe fourteen or fifteen hours together, against the strongest current, because he wished to return to his family. in order to form a true judgment of the muscular strength of the people, we should observe them in circumstances where their actions are determined by a necessity and a will equally energetic. we examined the ruins of santiago,* the structure of which is remarkable for its extreme solidity. (* on the map accompanying robertson's history of america, we find the name of this castle confounded with that of nueva cordoba. this latter denomination was formerly synonymous with cumana.--herrera, page .) the walls of freestone, five feet thick, have been blown up by mines; but we still found masses of seven or eight hundred feet square, which have scarcely a crack in them. our guide showed us a cistern (aljibe) thirty feet deep, which, though much damaged, furnishes water to the inhabitants of the peninsula of araya. this cistern was finished in , by the governor don juan de padilla guardiola, the same who built at cumana the small fort of santa maria. as the basin is covered with an arched vault, the water, which is of excellent quality, keeps very cool: the confervae, while they decompose the carburetted hydrogen, also shelter worms which hinder the propagation of small insects. it had been believed for ages, that the peninsula of araya was entirely destitute of springs of fresh water; but in , after many useless researches, the inhabitants of maniquarez succeeded in discovering some. in crossing the arid hills of cape cirial, we perceived a strong smell of petroleum. the wind blew from the direction in which the springs of this substance are found, and which were mentioned by the first historians of these countries.* (* oviedo terms it "a resinous, aromatic, and medicinal liquor.") near the village of maniquarez, the mica-slate* (* the piedra pelada of the creoles.) comes out from below the secondary rock, forming a chain of mountains from one hundred and fifty to one hundred and eighty toises in height. the direction of the primitive rock near cape sotto is from north-east to south-west; its strata incline fifty degrees to the north-west. the mica-slate is silvery white, of lamellar and undulated texture, and contains garnets. strata of quartz, the thickness of which varies from three to four toises, traverse the mica-slate, as we may observe in several ravines hollowed out by the waters. we detached with difficulty a fragment of cyanite from a block of splintered and milky quartz, which was isolated on the shore. this was the only time we found this substance in south america.* (* in new spain, the cyanite has been discovered only in the province of guatimala, at estancia grande,--del rio tablas min. page .) the potteries of maniquarez, celebrated from time immemorial, form a branch of industry which is exclusively in the hands of the indian women. the manufacture is still carried on according to the method used before the conquest. it indicates both the infancy of the art, and that unchangeability of manners which is characteristic of all the natives of america. three centuries have been insufficient to introduce the potter's-wheel, on a coast which is not above thirty or forty days' sail from spain. the natives have some confused notions with respect to the existence of this machine, and they would no doubt make use of it if it were introduced among them. the quarries whence they obtain the clay are half a league to the east of maniquarez. this clay is produced by natural decomposition of a mica-slate reddened by oxide of iron. the indian women prefer the part most abounding in mica; and with great skill fashion vessels two or three feet in diameter, giving them a very regular curve. as they are not acquainted with the use of ovens, they place twigs of desmanthus, cassia, and the arborescent capparis, around the pots, and bake them in the open air. to the east of the quarry which furnishes the clay is the ravine of la mina. it is asserted that, a short time after the conquest, some venetians extracted gold from the mica-slate. it appears that this metal was not collected in veins of quartz, but was found disseminated in the rock, as it is sometimes in granite and gneiss. at maniquarez we met with some creoles, who had been hunting at cubagua. deer of a small breed are so common in this uninhabited islet, that a single individual may kill three or four in a day. i know not by what accident these animals have got thither, for laet and other chroniclers of these countries, speaking of the foundation of new cadiz, mention only the great abundance of rabbits. the venado of cubagua belongs to one of those numerous species of small american deer, which zoologists have long confounded under the vague name of cervus mexicanus. it does not appear to be the same as the hind of the savannahs of cayenne, or the guazuti of paraguay, which live also in herds. its colour is a brownish red on the back, and white under the belly; and it is spotted like the axis. in the plains of cari we were shown, as a thing very rare in these hot climates, a variety quite white. it was a female of the size of the roebuck of europe, and of a very elegant shape. white varieties are found in the new continent even among the tigers. azara saw a jaguar, the skin of which was wholly white, with merely the shadow, as it might be termed, of a few circular spots. of all the productions on the coasts of araya, that which the people consider as the most extraordinary, or we may say the most marvellous, is 'the stone of the eyes,' (piedra de los ojos.) this calcareous substance is a frequent subject of conversation: being, according to the natural philosophy of the natives, both a stone and an animal. it is found in the sand, where it is motionless; but if placed on a polished surface, for instance on a pewter or earthen plate, it moves when excited by lemon juice. if placed in the eye, the supposed animal turns on itself, and expels every other foreign substance that has been accidentally introduced. at the new salt-works, and at the village of maniquarez, these stones of the eyes* were offered to us by hundreds, and the natives were anxious to show us the experiment of the lemon juice. (* they are found in the greatest abundance near the battery at the point of cape araya.) they even wished to put sand into our eyes, in order that we might ourselves try the efficacy of the remedy. it was easy to see that the stones are thin and porous opercula, which have formed part of small univalve shells. their diameter varies from one to four lines. one of their two surfaces is plane, and the other convex. these calcareous opercula effervesce with lemon juice, and put themselves in motion in proportion as the carbonic acid is disengaged. by the effect of a similar reaction, loaves placed in an oven move sometimes on a horizontal plane; a phenomenon that has given occasion, in europe, to the popular prejudice of enchanted ovens. the piedras de los ojos, introduced into the eye, act like the small pearls, and different round grains employed by the american savages to increase the flowing of tears. these explanations were little to the taste of the inhabitants of araya. nature has the appearance of greatness to man in proportion as she is veiled in mystery; and the ignorant are prone to put faith in everything that borders on the marvellous. proceeding along the southern coast, to the east of maniquarez, we find running out into the sea very near each other, three strips of land, bearing the names of punta de soto, punta de la brea, and punta guaratarito. in these parts the bottom of the sea is evidently formed of mica-slate, and from it near cape de la brea, but at eighty feet distant from the shore, there issues a spring of naphtha, the smell of which penetrates into the interior of the peninsula. it is necessary to wade into the sea up to the waist, to examine this interesting phenomenon. the waters are covered with zostera; and in the midst of a very extensive bank of weeds, we distinguish a free and circular spot of three feet in diameter, on which float a few scattered masses of ulva lactuca. here the springs are found. the bottom of the gulf is covered with sand; and the petroleum, which, from its transparency and its yellow colour, resembles naphtha, rises in jets, accompanied by air bubbles. on treading down the bottom with the foot, we perceive that these little springs change their place. the naphtha covers the surface of the sea to more than a thousand feet distant. if we suppose the dip of the strata to be regular, the mica-slate must be but a few toises below the sand. we have already observed, that the muriatiferous clay of araya contains solid and friable petroleum. this geological connection between the muriate of soda and the bitumens is evident wherever there are mines of sal-gem or salt springs: but a very remarkable fact is the existence of a fountain of naphtha in a primitive formation. all those hitherto known belong to secondary mountains;* (* as at pietra mala; fanano; mont zibio; and amiano (in these places are found the springs that furnish the naphtha burned in lamps in genoa) and also at baikal.) a circumstance which has been supposed to favour the idea that all mineral bitumens are owing to the destruction of vegetables and animals, or to the burning of coal. in the peninsula of araya, the naphtha flows from the primitive rock itself; and this phenomenon acquires new importance, when we recollect that the same primitive rocks contain the subterranean fires, that on the brink of burning craters the smell of petroleum is perceived from time to time, and that the greater part of the hot springs of america rise from gneiss and micaceous schist. after having examined the environs of maniquarez, we embarked at night in a fishing-boat for cumana. the small crazy boats employed by the natives here, bear testimony to the extreme calmness of the sea in these regions. our boat, though the best we could procure, was so leaky, that the pilot's son was constantly employed in baling out the water with a tutuma, or shell of the crescentia cujete (calabash). it often happens in the gulf of cariaco, and especially to the north of the peninsula of araya, that canoes laden with cocoa-nuts are upset in sailing too near the wind, and against the tide. the inhabitants of araya, whom we visited a second time on returning from the orinoco, have not forgotten that their peninsula was one of the points first peopled by the spaniards. they love to talk of the pearl fishery; of the ruins of the castle of santiago, which they hope to see some day rebuilt; and of everything that recalls to mind the ancient splendour of those countries. in china and japan those inventions are considered as recent, which have not been known above two thousand years; in the european colonies an event appears extremely old, if it dates back three centuries, or about the period of the discovery of america. chapter . . mountains of new andalucia. valley of the cumanacoa. summit of the cocollar. missions of the chayma indians. our first visit to the peninsula of araya was soon succeeded by an excursion to the mountains of the missions of the chayma indians, where a variety of interesting objects claimed our attention. we entered on a country studded with forests, and visited a convent surrounded by palm-trees and arborescent ferns. it was situated in a narrow valley, where we felt the enjoyment of a cool and delicious climate, in the centre of the torrid zone. the surrounding mountains contain caverns haunted by thousands of nocturnal birds; and, what affects the imagination more than all the wonders of the physical world, we find beyond these mountains a people lately nomad, and still nearly in a state of nature, wild without being barbarous. it was in the promontory of paria that columbus first descried the continent; there terminate these valleys, laid waste alternately by the warlike anthropophagic carib and by the commercial and polished nations of europe. at the beginning of the sixteenth century the ill-fated indians of the coasts of carupano, of macarapan, and of caracas, were treated in the same manner as the inhabitants of the coast of guinea in our days. the soil of the islands was cultivated, the vegetable produce of the old world was transplanted thither, but a regular system of colonization remained long unknown on the new continent. if the spaniards visited its shores, it was only to procure, either by violence or exchange, slaves, pearls, grains of gold, and dye-woods; and endeavours were made to ennoble the motives of this insatiable avarice by the pretence of enthusiastic zeal in the cause of religion. the trade in the copper-coloured indians was accompanied by the same acts of inhumanity as that which characterizes the traffic in african negroes; it was attended also by the same result, that of rendering both the conquerors and the conquered more ferocious. thence wars became more frequent among the natives; prisoners were dragged from the inland countries to the coast, to be sold to the whites, who loaded them with chains in their ships. yet the spaniards were at that period, and long after, one of the most polished nations of europe. the light which art and literature then shed over italy, was reflected on every nation whose language emanated from the same source as that of dante and petrarch. it might have been expected that a general improvement of manners would be the natural consequence of this noble awakening of the mind, this sublime soaring of the imagination. but in distant regions, wherever the thirst of wealth has introduced the abuse of power, the nations of europe, at every period of their history, have displayed the same character. the illustrious era of leo x was signalized in the new world by acts of cruelty that seemed to belong to the most barbarous ages. we are less surprised, however, at the horrible picture presented by the conquest of america when we think of the acts that are still perpetrated on the western coast of africa, notwithstanding the benefits of a more humane legislation. the principles adopted by charles v had abolished the slave trade on the new continent. but the conquistadores, by the continuation of their incursions, prolonged the system of petty warfare which diminished the american population, perpetuated national animosities, and during a long period crushed the seeds of rising civilization. at length the missionaries, under the protection of the secular arm, spoke words of peace. it was the privilege of religion to console humanity for a part of the evils committed in its name; to plead the cause of the natives before kings, to resist the violence of the commendatories, and to assemble wandering tribes into small communities called missions. but these institutions, useful at first in stopping the effusion of blood, and in laying the first basis of society, have become in their result hostile to its progress. the effects of this insulated system have been such that the indians have remained in a state little different from that in which they existed whilst yet their scattered dwellings were not collected round the habitation of a missionary. their number has considerably augmented, but the sphere of their ideas is not enlarged. they have progressively lost that vigour of character and that natural vivacity which in every state of society are the noble fruits of independence. by subjecting to invariable rules even the slightest actions of their domestic life, they have been rendered stupid by the effort to render them obedient. their subsistence is in general more certain, and their habits more pacific, but subject to the constraint and the dull monotony of the government of the missions, they show by their gloomy and reserved looks that they have not sacrificed their liberty to their repose without regret. on the th of september, at five in the morning, we began our journey to the missions of the chayma indians and the group of lofty mountains which traverse new andalusia. on account of the extreme difficulties of the road, we had been advised to reduce our baggage to a very small bulk. two beasts of burden were sufficient to carry our provision, our instruments, and the paper necessary to dry our plants. one chest contained a sextant, a dipping-needle, an apparatus to determine the magnetic variation, a few thermometers, and saussure's hygrometer. the greatest changes in the pressure of the air in these climates, on the coasts, amount only to to . of a line; and if at any given hour or place the height of the mercury be once marked, the variations which that height experiences throughout the whole year, at every hour of the day or night, may with some accuracy be determined. the morning was deliciously cool. the road, or rather path, which leads to cumanacoa, runs along the right bank of the manzanares, passing by the hospital of the capuchins, situated in a small wood of lignum-vitae and arborescent capparis.* (* these caper-trees are called in the country, by the names pachaca, olivo, and ajito: they are the capparis tenuisiliqua, jacq., c. ferruginea, c. emarginata, c. elliptica, c. reticulata, c. racemosa.) on leaving cumana we enjoyed during the short duration of the twilight, from the top of the hill of san francisco, an extensive view over the sea, the plain covered with bera* and its golden flowers (* palo sano, zygophyllum arboreum, jacq. the flowers have the smell of vanilla. it is cultivated in the gardens of the havannah under the strange name of the dictanno real (royal dittany).), and the mountains of the brigantine. we were struck by the great proximity in which the cordillera appeared before the disk of the rising sun had reached the horizon. the tint of the summits is of a deeper blue, their outline is more strongly marked, and their masses are more detached, as long as the transparency of the air is undisturbed by the vapours, which, after accumulating during the night in the valleys, rise in proportion as the atmosphere acquires warmth. at the hospital of the divina pastora the path turns to north-east, and stretches for two leagues over a soil without trees, and formerly levelled by the waters. we there found not only cactuses, tufts of cistus-leaved tribulus, and the beautiful purple euphorbia,* (* euphorbia tithymaloides.) but also the avicennia, the allionia, the sesuvium, the thalinum, and most of the portulaceous plants which grow on the banks of the gulf of cariaco. this geographical distribution of plants appears to designate the limits of the ancient coast, and to prove that the hills along the southern side of which we were passing, formed heretofore a small island, separated from the continent by an arm of the sea. after walking two hours, we arrived at the foot of the high chain of the interior mountains, which stretches from east to west; from the brigantine to the cerro de san lorenzo. there, new rocks appear, and with them another aspect of vegetation. every object assumes a more majestic and picturesque character; the soil, watered by springs, is furrowed in every direction; trees of gigantic height, covered with lianas, rise from the ravines; their bark, black and burnt by the double action of the light and the oxygen of the atmosphere, contrasts with the fresh verdure of the pothos and dracontium, the tough and shining leaves of which are sometimes several feet long. the parasite monocotyledons take between the tropics the place of the moss and lichens of our northern zone. as we advanced, the forms and grouping of the rocks reminded us of switzerland and the tyrol. the heliconia, costus, maranta, and other plants of the family of the balisiers (canna indica), which near the coasts vegetate only in damp and low places, flourish in the american alps at considerable height. thus, by a singular similitude, in the torrid zone, under the influence of an atmosphere continually loaded with vapours the mountain vegetation presents the same features as the vegetation of the marshes in the north of europe on soil moistened by melting snow.* (* wahlenberg, de vegetatione helvetiae et summi septentrionis pages , .) before we leave the plains of cumana, and the breccia, or calcareous sandstone, which constitutes the soil of the seaside, we will describe the different strata of which this very recent formation is composed, as we observed it on the back of the hills that surround the castle of san antonio. this breccia, or calcareous sandstone, is a local and partial formation, peculiar to the peninsula of araya, the coasts of cumana, and caracas. we again found it at cabo blanco, to the west of the port of guayra, where it contains, besides broken shells and madrepores, fragments, often angular, of quartz and gneiss. this circumstance assimilates the breccia to that recent sandstone called by the german mineralogists nagelfluhe, which covers so great a part of switzerland to the height of a thousand toises, without presenting any trace of marine productions. near cumana the formation of the calcareous breccia contains:--first, a compact whitish grey limestone, the strata of which, sometimes horizontal, sometimes irregularly inclined, are from five to six inches thick; some beds are almost unmixed with petrifactions, but in the greatest part the cardites, the turbinites, the ostracites, and shells of small dimension, are found so closely connected, that the calcareous matter forms only a cement, by which the grains of quartz and the organized bodies are united: second, a calcareous sandstone, in which the grains of sand are much more frequent than the petrified shells; other strata form a sandstone entirely free from organic fragments, yielding but a small effervescence with acids, and enclosing not lamellae of mica, but nodules of compact brown iron-ore: third, beds of indurated clay containing selenite and lamellar gypsum. the breccia, or agglomerate of the sea-coast, just described, has a white tint, and it lies immediately on the calcareous formation of cumanacoa, which is of a bluish grey. these two rocks form a contrast no less striking than the molasse (bur-stone) of the pays de vaud, with the calcareous limestone of the jura. it must be observed, that, by contact of the two formations lying upon each other, the beds of the limestone of cumanacoa, which i consider as an alpine limestone, are always largely mixed with clay and marl. lying, like the mica-slate of araya, north-east and south-west, they are inclined, near punta delgada, under an angle of degrees to south-east. we traversed the forest by a narrow path, along a rivulet, which rolls foaming over a bed of rocks. we observed, that the vegetation was more brilliant, wherever the alpine limestone was covered by a quartzose sandstone without petrifactions, and very different from the breccia of the sea-coast. the cause of this phenomenon depends probably not so much on the nature of the ground, as on the greater humidity of the soil. the quartzose sandstone contains thin strata of a blackish clay-slate,* (* schieferthon.) which might easily be confounded with the secondary thonschiefer; and these strata hinder the water from filtering into the crevices, of which the alpine limestone is full. this last offers to view here, as in saltzburg, and on the chain of the apennines, broken and steep beds. the sandstone, on the contrary, wherever it is seated on the calcareous rock, renders the aspect of the scene less wild. the hills which it forms appear more rounded, and the gentler slopes are covered with a thicker mould. in humid places, where the sandstone envelopes the alpine limestone, some trace of cultivation is constantly found. we met with huts inhabited by mestizoes in the ravine of los frailes, as well as between the cuesta de caneyes, and the rio guriental. each of these huts stands in the centre of an enclosure, containing plantains, papaw-trees, sugar-canes, and maize. we might be surprised at the small extent of these cultivated spots, if we did not recollect that an acre planted with plantains* (* musa paradisiaca.) produces nearly twenty times as much food as the same space sown with corn. in europe, our wheat, barley, and rye cover vast spaces of ground; and in general the arable lands touch each other, wherever the inhabitants live upon corn. it is different under the torrid zone, where man obtains food from plants which yield more abundant and earlier harvests. in those favoured climes, the fertility of the soil is proportioned to the heat and humidity of the atmosphere. an immense population finds abundant nourishment within a narrow space, covered with plantains, cassava, yams, and maize. the isolated situation of the huts dispersed through the forest indicates to the traveller the fecundity of nature, where a small spot of cultivated land suffices for the wants of several families. these considerations on the agriculture of the torrid zone involuntarily remind us of the intimate connexion existing between the extent of land cleared, and the progress of society. the richness of the soil, and the vigour of organic life, by multiplying the means of subsistence, retard the progress of nations in the paths of civilization. under so mild and uniform a climate, the only urgent want of man is that of food. this want only, excites him to labour; and we may easily conceive why, in the midst of abundance, beneath the shade of the plantain and bread-fruit tree, the intellectual faculties unfold themselves less rapidly than under a rigorous sky, in the region of corn, where our race is engaged in a perpetual struggle with the elements. in europe we estimate the number of the inhabitants of a country by the extent of cultivation: within the tropics, on the contrary, in the warmest and most humid parts of south america, very populous provinces appear almost deserted; because man, to find nourishment, cultivates but a small number of acres. these circumstances modify the physical appearance of the country and the character of its inhabitants, giving to both a peculiar physiognomy; the wild and uncultivated stamp which belongs to nature, ere its primitive type has been altered by art. without neighbours, almost unconnected with the rest of mankind, each family of settlers forms a separate tribe. this insulated state arrests or retards the progress of civilization, which advances only in proportion as society becomes numerous, and its connexions more intimate and multiplied. but, on the other hand, it is solitude that develops and strengthens in man the sentiment of liberty and independence; and gives birth to that noble pride of character which has at all times distinguished the castilian race. from these causes, the land in the most populous regions of equinoctial america still retains a wild aspect, which is destroyed in temperate climates by the cultivation of corn. within the tropics the agricultural nations occupy less ground: man has there less extended his empire; he may be said to appear, not as an absolute master, who changes at will the surface of the soil, but as a transient guest, who quietly enjoys the gifts of nature. there, in the neighbourhood of the most populous cities, the land remains studded with forests, or covered with a thick mould, unfurrowed by the plough. spontaneous vegetation still predominates over cultivated plants, and determines the aspect of the landscape. it is probable that this state of things will change very slowly. if in our temperate regions the cultivation of corn contributes to throw a dull uniformity upon the land we have cleared, we cannot doubt, that, even with increasing population, the torrid zone will preserve that majesty of vegetable forms, those marks of an unsubdued, virgin nature, which render it so attractive and so picturesque. thus it is that, by a remarkable concatenation of physical and moral causes, the choice and production of alimentary plants have an influence on three important objects at once; the association or the isolated state of families, the more or less rapid progress of civilization, and the individual character of the landscape. in proportion as we penetrated into the forest, the barometer indicated the progressive elevation of the land. the trunks of the trees presented here an extraordinary phenomenon; a gramineous plant, with verticillate branches,* climbs, like a liana, eight or ten feet high, and forms festoons, which cross the path, and swing about with the wind. (* carice, analogous to the chusque of santa fe, of the group of the nastusas. this gramineous plant is excellent pasture for mules.) we halted, about three o'clock in the afternoon, on a small flat, known by the name of quetepe, and situated about one hundred and ninety toises above the level of the sea. a few small houses have been erected near a spring, well known by the natives for its coolness and great salubrity. we found the water delicious. its temperature was only . degrees of the centigrade thermometer, while that of the air was . degrees. the springs which descend from the neighbouring mountains of a greater height often indicate a too rapid decrement of heat. if indeed we suppose the mean temperature of the water on the coast of cumana equal to degrees, we must conclude, unless other local causes modify the temperature of the springs, that the spring of quetepe acquires its great coolness at more than toises of absolute elevation. with respect to the springs which gush out in the plains of the torrid zone, or at a small elevation, it may be observed, in general, that it is only in regions where the mean temperature of summer essentially differs from that of the whole year, that the inhabitants have extremely cold spring water during the season of great heat. the laplanders, near umea and soersele, in the th degree of latitude, drink spring-water, the temperature of which, in the month of august, is scarcely two or three degrees above freezing point; while during the day the heat of the air rises in the shade, in the same northern regions, to or degrees. in the temperate climates of france and germany, the difference between the air and the springs never exceeds or degrees; between the tropics it seldom rises to or degrees. it is easy to account for these phenomena, when we recollect that the interior of the globe, and the subterraneous waters, have a temperature almost identical with the annual mean temperature of the air; and that the latter differs from the mean heat of summer, in proportion to the distance from the equator. from the top of a hill of sandstone, which overlooks the spring of quetepe, we had a magnificent view of the sea, of cape macanao, and the peninsula of maniquarez. at our feet an immense forest extended to the edge of the ocean. the tops of the trees, intertwined with lianas, and crowned with long wreaths of flowers, formed a vast carpet of verdure, the dark tint of which augmented the splendour of the aerial light. this picture struck us the more forcibly, as we then first beheld those great masses of tropical vegetation. on the hill of quetepe, at the foot of the malpighia cocollobaefolia, the leaves of which are extremely coriaceous, we gathered, among tufts of the polygala montana, the first melastomas, especially that beautiful species described under the name of the melastoma rufescens. as we advanced toward the south-west, the soil became dry and sandy. we climbed a group of mountains, which separate the coast from the vast plains, or savannahs, bordered by the orinoco. that part of the group, over which passes the road to cumanacoa, is destitute of vegetation, and has steep declivities both on the north and the south. it has received the name of the imposible, because it is believed that, in the case of hostile invasion, this ridge of mountains would be inaccessible to the enemy, and would offer an asylum to the inhabitants of cumana. we reached the top a little before sunset, and i had scarcely time to take a few horary angles, to determine the longitude of the place by means of the chronometer. the view from the imposible is finer and more extensive than that from the table-land of quetepe. we distinguished clearly by the naked eye the flattened top of the brigantine (the position of which it would be important to fix accurately), the embarcadero or landing-place, and the roadstead of cumana. the rocky coast of the peninsula of araya was discernible in its whole length. we were particularly struck with the extraordinary configuration of a port, known by the name of laguna grande, or laguna del obispo. a vast basin, surrounded by high mountains, communicates with the gulf of cariaco by a narrow channel which admits only of the passage of one ship at a time. this port is capable of containing several squadrons at once. it is an uninhabited place, but annually frequented by vessels, which carry mules to the west india islands. there are some pasture grounds at the farther end of the bay. we traced the sinuosities of this arm of the sea, which, like a river, has dug a bed between perpendicular rocks destitute of vegetation. this singular prospect reminded us of the fanciful landscape which leonardo da vinci has made the back-ground of his famous portrait of mona lisa, the wife of francisco del giacondo. we could observe by the chronometer the moment when the disk of the sun touched the horizon of the sea. the first contact was at hours minutes seconds; the second, at hours minutes seconds; mean time. this observation, which is not unimportant for the theory of terrestrial refractions, was made on the summit of the mountain, at the absolute height of toises. the setting of the sun was attended by a very rapid cooling of the air. three minutes after the last apparent contact of the disk with the horizon of the sea, the thermometer suddenly fell from . to . degrees. was this extraordinary refrigeration owing to some descending current? the air was however calm, and no horizontal wind was felt. we passed the night in a house where there was a military post consisting of eight men, under the command of a spanish serjeant. it was an hospital, built by the side of a powder magazine. when cumana, after the capture of trinidad by the english, in , was threatened with an attack, many of the inhabitants fled to cumanacoa, and deposited whatever articles of value they possessed in sheds hastily constructed on the top of the imposible. it was then resolved, in case of any unforeseen invasion, to abandon the castle of san antonio, after a short resistance, and to concentrate the whole force of the province round the mountains, which may be considered as the key of the llanos. the top of the imposible, as nearly as i could perceive, is covered with a quartzose sandstone, free from petrifactions. here, as on the ridge of the neighbouring mountains, the strata pretty regularly take the direction from north-north-east to south-south-west. this direction is also most common in the primitive formations in the peninsula of araya, and along the coasts of venezuela. on the northern declivity of the imposible, near the penas negras, an abundant spring issues from sandstone, which alternates with a schistose clay. we remarked on this point fractured strata, which lie from north-west to south-east, and the dip of which is almost perpendicular. the llaneros, or inhabitants of the plains, send their produce, especially maize, leather, and cattle, to the port of cumana by the road over the imposible. we continually saw mules arrive, driven by indians or mulattoes. several parts of the vast forests which surround the mountain, had taken fire. reddish flames, half enveloped in clouds of smoke, presented a very grand spectacle. the inhabitants set fire to the forests, to improve the pasturage, and to destroy the shrubs that choke the grass. enormous conflagrations, too, are often caused by the carelessness of the indians, who neglect, when they travel, to extinguish the fires by which they have dressed their food. these accidents contribute to diminish the number of old trees in the road from cumana to cumanacoa; and the inhabitants observe justly, that, in several parts of their province, the dryness has increased, not only because every year the frequency of earthquakes causes more crevices in the soil; but also because it is now less thickly wooded than it was at the time of the conquest. i arose during the night to determine the latitude of the place by the passage of fomalhaut over the meridian; but the observation was lost, owing to the time i employed in taking the level of the artificial horizon. it was midnight, and i was benumbed with cold, as were also our guides: yet the thermometer kept at . degrees. at cumana i have never seen it sink below degrees; but then the house in which we dwelt on the imposible was toises above the level of the sea. at the casa de la polvora i determined the dip of the magnetic needle, which was . degrees.* (* the magnetic dip is always measured in this work, according to the centesimal division, if the contrary be not expressly mentioned.) the number of oscillations correspondent to minutes of time was . the intensity of the magnetic forces had consequently augmented from the coast to the mountain, perhaps from the influence of some ferruginous matter, hidden in the strata of sandstone which cover the alpine limestone. we left the imposible on the th of september before sunrise. the descent is very dangerous for beasts of burden; the path being in general but fifteen inches broad, and bordered by precipices. in descending the mountain, we observed the rock of alpine limestone reappearing under the sandstone. the strata being generally inclined to the south and south-east, a great number of springs gush out on the southern side of the mountain. in the rainy season of the year, these springs form torrents, which descend in cascades, shaded by the hura, the cuspa, and the silver-leaved cecropia or trumpet-tree. the cuspa, a very common tree in the environs of cumana and of bordones, is yet unknown to the botanists of europe. it was long used only for the building of houses, and has become celebrated since , under the name of the cascarilla or bark-tree (cinchona) of new andalusia. its trunk rises scarcely above fifteen or twenty feet. its alternate leaves are smooth, entire, and oval.* (* at the summit of the boughs, the leaves are sometimes opposite to each other, but invariably without stipules.) its bark very thin, and of a pale yellow, is a powerful febrifuge. it is even more bitter than the bark of the real cinchona, but is less disagreeable. the cuspa is administered with the greatest success, in a spirituous tincture, and in aqueous infusion, both in intermittent and in malignant fevers. on the coasts of new andalusia, the cuspa is considered as a kind of cinchona; and we were assured, that some aragonese monks, who had long resided in the kingdom of new grenada, recognised this tree from the resemblance of its leaves to those of the real peruvian bark-tree. this, however, is unfounded; since it is precisely by the disposition of the leaves, and the absence of stipules, that the cuspa differs totally from the trees of the rubiaceous family. it may be said to resemble the family of the honeysuckle, or caprifoliaceous plants, one section of which has alternate leaves, and among which we find several cornel-trees, remarkable for their febrifuge properties.* (* cornus florida, and c. sericea of the united states.--walker on the virtues of the cornus and the cinchona compared. philadelphia .) the taste, at once bitter and astringent, and the yellow colour of the bark led to the discovery of the febrifugal virtue of the cuspa. as it blossoms at the end of november, we did not see it in flower, and we know not to what genus it belongs; and i have in vain for several years past applied to our friends at cumana for specimens of the flower and fruit. i hope that the botanical determination of the bark-tree of new andalusia will one day fix the attention of travellers, who visit this region after us; and that they will not confound, notwithstanding the analogy of the names, the cuspa with the cuspare. the latter not only vegetates in the missions of the rio carony, but also to the west of cumana, in the gulf of santa fe. it furnishes the druggists of europe with the famous cortex angosturae, and forms the genus bonplandia, described by m. willdenouw in the memoirs of the academy of berlin, from notes communicated to him by us. it is singular that, during our long abode on the coast of cumana and the caracas, on the banks of the apure, the orinoco, and the rio negro, in an extent of country comprising forty thousand square leagues, we never met with one of those numerous species of cinchona, or exostema, which are peculiar to the low and warm regions of the tropics, especially to the archipelago of the west india islands. yet we are far from affirming, that, throughout the whole of the eastern part of south america, from porto bello to cayenne, or from the equator to the th degree of north latitude between the meridians of and degrees, the cinchona absolutely does not exist. how can we be expected to know completely the flora of so vast an extent of country? but, when we recollect, that even in mexico no species of the genera cinchona and exostema has been discovered, either in the central table-land or in the plains, we are led to believe, that the mountainous islands of the west indies and the cordillera of the andes have peculiar floras; and that they possess particular species of vegetation, which have neither passed from the islands to the continent, nor from south america to the coasts of new spain. it may be observed farther, that, when we reflect on the numerous analogies which exist between the properties of plants and their external forms, we are surprised to find qualities eminently febrifuge in the bark of trees belonging to different genera, and even different families.* (* it may be somewhat interesting to chemistry, physiology, and descriptive botany, to consider under the same point of view the plants which have been employed in intermittent fevers with different degrees of success. we find among rubiaceous plants, besides the cinchonas and exostemas, the coutarea speciosa or cayenne bark, the portlandia grandiflora of the west indies, another portlandia discovered by m. sesse at mexico, the pinkneia pubescens of the united states, the berry of the coffee-tree, and perhaps the macrocnemum corymbosum, and the guettarda coccinea; among magnoliaceous plants, the tulip-tree and the magnolia glauca; among zanthoxylaceous plants, the cuspare of angostura, known in america under the name of orinoco bark, and the zanthoxylon caribaeum; among leguminous plants, the geoffraeas, the swietenia febrifuga, the aeschynomene grandiflora, the caesalpina bonducella; among caprifoliaceous plants, the cornus florida and the cuspa of cumana; among rosaceous plants, the cerasus virginiana and the geum urbanum; among amentaceous plants, the willows, oaks, and birch-trees, of which the alcoholic tincture is used in russia by the common people; the populus tremuloides, etc.; among anonaceous plants, the uvaria febrifuga, the fruit of which we saw administered with success in the missions of spanish guiana; among simarubaceous plants, the quassia amara, celebrated in the feverish plains of surinam; among terebinthaceous plants, the rhus glabrum; among euphorbiaceous plants, the croton cascarilla; among composite plants, the eupatorium perfoliatum, the febrifuge qualities of which are known to the savages of north america. of the tulip-tree and the quassia, it is the bark of the roots that is used. eminent febrifuge virtues have also been found in the cortical part of the roots of the cinchona condaminea at loxa; but it is fortunate, for the preservation of the species, that the roots of the real cinchona are not employed in pharmacy. chemical researches are yet wanting upon the very powerful bitters contained in the roots of the zanthoriza apiifolia, and the actaea racemosa: the latter have sometimes been employed with success as a remedy against the epidemic yellow fever in new york.) some of these barks so much resemble each other, that it is not easy to distinguish them at first sight. but before we examine the question, whether we shall one day discover, in the real cinchona, in the cuspa of cumana, the cortex angosturae, the indian swietenia, the willows of europe, the berries of the coffee-tree and uvaria, a matter uniformly diffused, and exhibiting (like starch, caoutchouc, and camphor) the same chemical properties in different plants, we may ask whether, in the present state of physiology and medicine, a febrifuge principle ought to be admitted. is it not probable, that the particular derangement in the organization, known under the vague name of the febrile state, and in which both the vascular and the nervous systems are at the same time attacked, yields to remedies which do not operate by the same principle, by the same mode of action on the same organs, by the same play of chemical and electrical attractions? we shall here confine ourselves to this observation, that, in the species of the genus cinchona, the antifebrile virtues do not appear to belong to the tannin (which is only accidentally mingled in them), or to the cinchonate of lime; but in a resiniform matter, soluble both by alcohol and by water, and which, it is believed, is composed of two principles, the cinchonic bitter and the cinchonic red.* (* in french, l'amer et le rouge cinchoniques.) may it then be admitted, that this resiniform matter, which possesses different degrees of energy according to the combinations by which it is modified, is found in all febrifuge substances? those by which the sulphate of iron is precipitated of a green colour, like the real cinchona, the bark of the white willow, and the horned perisperm of the coffee-tree, do not on this account denote identity of chemical composition;* and that identity might even exist, without our concluding that the medical virtues were analogous. (* the cuspare bark (cort. angosturae) yields with iron a yellow precipitate; yet it is employed on the banks of the orinoco, and particularly at the town of st. thomas of angostura, as an excellent cinchona; and on the other hand, the bark of the common cherry tree, which has scarcely any febrifuge quality, yields a green precipitate like the real cinchonas. notwithstanding the extreme imperfection of vegetable chemistry, the experiments already made on cinchonas sufficiently show, that to judge of the febrifuge virtues of a bark, we must not attach too much importance either to the principle which turns to green the oxides of iron, or to the tannin, or to the matter which precipitates infusions of tan.) we see that specimens of sugar and tannin extracted from plants, not of the same family, present numerous differences: while the comparative analysis of sugar, gum, and starch; the discovery of the radical of the prussic acid (the effects of which are so powerful on the organization), and many other phenomena of vegetable chemistry, clearly prove that substances composed of identical elements, few in number and proportional in quantity, exhibit the most heterogeneous properties, on account of that particular mode of combination which corpuscular chemistry calls the arrangement of the particles. leaving the ravine which descends from the imposible, we entered a thick forest traversed by many small rivers, which are easily forded. we observed that the cecropia, which in the disposition of its branches and its slender trunk, resembles the palm-tree, is covered with leaves more or less silvery, in proportion as the soil is dry or moist. we saw some small plants of the cecropia, the leaves of which were on both sides entirely green.* (* is not the cecropia concolor of willdenouw a variety of the cecropia peltata?) the roots of these trees are hid under tufts of dorstenia, which flourishes only in humid and shady places. in the midst of the forest, on the banks of the rio cedeno, as well as on the southern declivity of the cocollar, we find, in their wild state, papaw and orange-trees, bearing large and sweet fruit. these are probably the remains of some conucos, or indian plantations; for in those countries the orange-tree cannot be counted among the indigenous plants, any more than the banana-tree, the papaw-tree, maize, cassava, and many other useful plants, with the true country of which we are unacquainted, though they have accompanied man in his migrations from the remotest times. when a traveller newly arrived from europe penetrates for the first time into the forests of south america, he beholds nature under an unexpected aspect. he feels at every step, that he is not on the confines but in the centre of the torrid zone; not in one of the west india islands, but on a vast continent where everything is gigantic,--mountains, rivers, and the mass of vegetation. if he feel strongly the beauty of picturesque scenery he can scarcely define the various emotions which crowd upon his mind; he can scarcely distinguish what most excites his admiration, the deep silence of those solitudes, the individual beauty and contrast of forms, or that vigour and freshness of vegetable life which characterize the climate of the tropics. it might be said that the earth, overloaded with plants, does not allow them space enough to unfold themselves. the trunks of the trees are everywhere concealed under a thick carpet of verdure; and if we carefully transplanted the orchideae, the pipers, and the pothoses, nourished by a single courbaril, or american fig-tree,* (* ficus nymphaeifolia.) we should cover a vast extent of ground. by this singular assemblage, the forests, as well as the flanks of the rocks and mountains, enlarge the domains of organic nature. the same lianas which creep on the ground, reach the tops of the trees, and pass from one to another at the height of more than a hundred feet. thus, by the continual interlacing of parasite plants, the botanist is often led to confound one with another, the flowers, the fruits, and leaves, which belong to different species. we walked for some hours under the shade of these arcades, which scarcely admit a glimpse of the sky; the latter appeared to me of an indigo blue, the deeper in shade because the green of the equinoctial plants is generally of a stronger hue, with somewhat of a brownish tint. a great fern tree,* (* possibly our aspidium caducum.) very different from the polypodium arboreum of the west indies, rose above masses of scattered rocks. in this place we were struck for the first time with the sight of those nests in the shape of bottles, or small bags, which are suspended from the branches of the lowest trees, and which attest the wonderful industry of the orioles, which mingle their warbling with the hoarse cries of the parrots and the macaws. these last, so well known for their vivid colours, fly only in pairs, while the real parrots wander about in flocks of several hundreds. a man must have lived in those regions, particularly in the hot valleys of the andes, to conceive how these birds sometimes drown with their voices the noise of the torrents, which dash down from rock to rock. we left the forests, at the distance of somewhat more than a league from the village of san fernando. a narrow path led, after many windings, into an open but extremely humid country. in such a site in the temperate zone, the cyperaceous and gramineous plants would have formed vast meadows; here the soil abounded in aquatic plants, with sagittate leaves, and especially in basil plants, among which we noticed the fine flowers of the costus, the thalia, and the heliconia. these succulent plants are from eight to ten feet high, and in europe one of their groups would be considered as a little wood. near san fernando the evaporation caused by the action of the sun was so great that, being very lightly clothed, we felt ourselves as wet as in a vapour bath. the road was bordered with a kind of bamboo,* (* bambusa guadua.) which the indians call iagua, or guadua, and which is more than forty feet in height. nothing can exceed the elegance of this arborescent gramen. the form and disposition of its leaves give it a character of lightness which contrasts agreeably with its height. the smooth and glossy trunk of the iagua generally bends towards the banks of rivulets, and it waves with the slightest breath of air. the highest reeds* in the south of europe (* arundo donax.), can give no idea of the aspect of the arborescent gramina. the bamboo and fern-tree are, of all the vegetable forms between the tropics, those which make the most powerful impression on the imagination of the traveller. bamboos are less common in south america than is usually believed. they are almost wanting in the marshes and in the vast inundated plains of the lower orinoco, the apure, and the atabapo, while they form thick woods, several leagues in length, in the north-west, in new grenada, and in the kingdom of quito. it might be said that the western declivity of the andes is their true country; and, what is remarkable enough, we found them not only in the low regions at the level of the ocean, but also in the lofty valleys of the cordilleras, at the height of toises. the road skirted with the bamboos above mentioned led us to the small village of san fernando, situated in a narrow plain, surrounded by very steep calcareous rocks. this was the first mission* we saw in america. (* a certain number of habitations collected round a church, with a missionary monk performing the ministerial duties, is called in the spanish colonies mision, or pueblo de mision. indian villages, governed by a priest, are called pueblos de doctrina. a distinction is made between the cura doctrinero, who is the priest of an indian parish, and the cura rector, priest of a village inhabited by whites and men of mixed race.) the houses, or rather the huts of the chayma indians, though separate from each other, are not surrounded by gardens. the streets, which are wide and very straight, cross each other at right angles. the walls of the huts are made of clay, strengthened by lianas. the uniformity of these huts, the grave and taciturn air of their inhabitants, and the extreme neatness of the dwellings, reminded us of the establishments of the moravian brethren. besides their own gardens, every indian family helps to cultivate the garden of the community, or, as it is called, the conuco de la comunidad, which is situated at some distance from the village. in this conuco the adults of each sex work one hour in the morning and one in the evening. in the missions nearest the coast the garden of the community is generally a sugar or indigo plantation, under the direction of the missionary; and its produce, if the law were strictly observed, could be employed only for the support of the church and the purchase of sacerdotal ornaments. the great square of san fernando, in the centre of the village, contains the church, the dwelling of the missionary, and a very humble-looking edifice pompously called the king's house (casa del rey). this is a caravanserai, destined for lodging travellers; and, as we often experienced, infinitely valuable in a country where the name of an inn is still unknown. the casas del rey are to be found in all the spanish colonies, and may be deemed an imitation of the tambos of peru, which were established in conformity with the laws of manco capac. we had been recommended to the friars who govern the missions of the chayma indians, by their syndic, who resides at cumana. this recommendation was the more useful to us, as the missionaries, either from zeal for the purity of the morals of their parishioners, or to conceal the monastic system from the indiscreet curiosity of strangers, often adhere with rigour to an old regulation, by which a white man of the secular state is not permitted to sojourn more than one night in an indian village. the missions form (i will not say according to their primitive and canonical institutions, but in reality) a distinct and nearly independent hierarchy, the views of which seldom accord with those of the secular clergy. the missionary of san fernando was a capuchin, a native of aragon, far advanced in years, but strong and healthy. his extreme corpulency, his hilarity, the interest he took in battles and sieges, ill accorded with the ideas we form in northern countries of the melancholy reveries and the contemplative life of missionaries. though extremely busy about a cow which was to be killed next day, the old monk received us with kindness, and permitted us to hang up our hammocks in a gallery of his house. seated, without doing anything, the greater part of the day, in an armchair of red wood, he bitterly complained of what he called the indolence and ignorance of his countrymen. our missionary, however, seemed well satisfied with his situation. he treated the indians with mildness; he beheld his mission prosper, and he praised with enthusiasm the waters, the bananas, and the dairy-produce of the district. the sight of our instruments, our books, and our dried plants, drew from him a sarcastic smile; and he acknowledged, with the naivete peculiar to the inhabitants of those countries, that of all the enjoyments of life, without excepting sleep, none was comparable to the pleasure of eating good beef (carne de vaca): thus does sensuality obtain an ascendancy, where there is no occupation for the mind. the mission of san fernando was founded about the end of the th century, near the junction of the small rivers of the manzanares and lucasperez. a fire, which consumed the church and the huts of the indians, induced the capuchins to build the village in its present fine situation. the number of families is increased to one hundred, and the missionary observed to us, that the custom of marrying at thirteen or fourteen years of age contributes greatly to this rapid increase of population. he denied that old age was so premature among the chaymas, as is commonly believed in europe. the government of these indian parishes is very complicated; they have their governor, their major-alguazils, and their militia-commanders, all copper-coloured natives. the company of archers have their colours, and perform their exercise with the bow and arrow, in shooting at a mark; this is the national guard (militia) of the country. this military establishment, under a purely monastic system, seemed to us very singular. on the night of the th of september, and the following morning, there was a thick fog; yet we were not more than a hundred toises above the level of the sea. i determined geometrically, at the moment of our departure, the height of the great calcareous mountain which rises at toises distance to the south of san fernando, and forms a perpendicular cliff on the north side. it is only toises higher than the great square; but naked masses of rock, which here exhibit themselves in the midst of a thick vegetation, give it a very majestic aspect. the road from san fernando to cumana passes amidst small plantations, through an open and humid valley. we forded a number of rivulets. in the shade the thermometer did not rise above degrees: but we were exposed to the direct rays of the sun, because the bamboos, which skirted the road, afforded but small shelter, and we suffered greatly from the heat. we passed through the village of arenas, inhabited by indians, of the same race as those at san fernando. but arenas is no longer a mission; and the natives, governed by a regular priest,* (* the four villages of arenas, macarapana, mariguitar, and aricagua, founded by aragonese capuchins, are called doctrinas de encomienda.) are better clothed, and more civilized. their church is also distinguished in the country by some rude paintings which adorn its walls. a narrow border encloses figures of armadilloes, caymans, jaguars, and other animals peculiar to the new world. in this village lives a labourer, francisco lozano, who presented a highly curious physiological phenomenon. this man has suckled a child with his own milk. the mother having fallen sick, the father, to quiet the infant, took it into his bed, and pressed it to his bosom. lozano, then thirty-two years of age, had never before remarked that he had milk: but the irritation of the nipple, sucked by the child, caused the accumulation of that liquid. the milk was thick and very sweet. the father, astonished at the increased size of his breast, suckled his child two or three times a day during five months. he drew on himself the attention of his neighbours, but he never thought, as he probably would have done in europe, of deriving any advantage from the curiosity he excited. we saw the certificate, which had been drawn up on the spot, to attest this remarkable fact, eye-witnesses of which are still living. they assured us that, during this suckling, the child had no other nourishment than the milk of his father. lozano, who was not at arenas during our journey in the missions, came to us at cumana. he was accompanied by his son, then thirteen or fourteen years of age. m. bonpland examined with attention the father's breasts, and found them wrinkled like those of a woman who has given suck. he observed that the left breast in particular was much enlarged; which lozano explained to us from the circumstance, that the two breasts did not furnish milk in the same abundance. don vicente emparan, governor of the province, sent a circumstantial account of this phenomenon to cadiz. it is not a very uncommon circumstance, to find, among animals, males whose breasts contain milk; and climate does not appear to exercise any marked influence on the greater or less abundance of this secretion. the ancients cite the milk of the he-goats of lemnos and corsica. in our own time, we have seen in hanover, a he-goat, which for a great number of years was milked every other day, and yielded more milk than a female goat. among the signs of the alleged weakness of the americans, travellers have mentioned the milk contained in the breasts of men. it is, however, improbable, that it has ever been observed in a whole tribe, in some part of america unknown to modern travellers; and i can affirm that at present it is not more common in the new continent, than in the old. the labourer of arenas, whose case has just been mentioned, was not of the copper-coloured race of chayma indians, but was a white man, descended from europeans. moreover, the anatomists of st. petersburgh have observed that, among the lower orders of the people in russia, milk in the breasts of men is much more frequent than among the more southern nations: yet the russians have never been deemed weak and effeminate. there is among the varieties of the human species a race of men whose breasts at the age of puberty acquire a considerable bulk. lozano did not belong to that race; and he often repeated to us his conviction, that it was only the irritation of the nipple, in consequence of the suction, which caused the flow of milk. when we reflect on the whole of the vital phenomena, we find that no one of them is entirely isolated. in every age examples are cited of very young girls and women in extreme old age, who have suckled children. among men these examples are more rare; and after numerous researches, i have not found above two or three. one is cited by the anatomist of verona, alexander benedictus, who lived about the end of the fifteenth century. he relates the history of an inhabitant of syria, who, to calm the fretfulness of his child, after the death of the mother, pressed it to his bosom. the milk soon became so abundant, that the father could take on himself the nourishment of his child without assistance. other examples are related by santorellus, faria, and robert, bishop of cork. the greater part of these phenomena having been noticed in times very remote, it is not uninteresting to physiology, that we can confirm them in our own days. on approaching the town of cumanacoa we found a more level soil, and a valley enlarging itself progressively. this small town is situated in a naked plain, almost circular, and surrounded by lofty mountains. it was founded in by domingo arias, on the return of an expedition to the mouth of the guarapiche, undertaken with the view of destroying an establishment which some french freebooters had attempted to found. the new town was first called san baltazar de las arias; but the indian name cumanacoa prevailed; in like manner the name of santiago de leon, still to be found in our maps, is forgotten in that of caracas. on opening the barometer we were struck at seeing the column of mercury scarcely . lines shorter than on the coasts. the plain, or rather the table-land, on which the town of cumanacoa is situated, is not more than toises above the level of the sea, which is three or four times less than is supposed by the inhabitants of cumana, on account of their exaggerated ideas of the cold of cumanacoa. but the difference of climate observable between places so near each other is perhaps less owing to comparative height than to local circumstances. among these causes we may cite the proximity of the forests; the frequency of descending currents, so common in these valleys, closed on every side; the abundance of rain; and those thick fogs which diminish during a great part of the year the direct action of the solar rays. the decrement of the heat being nearly the same within the tropics, and during the summer under the temperate zone, the small difference of level of one hundred toises should produce only a change in the mean temperature of or . degrees. but we shall soon find that at cumanacoa the difference rises to more than four degrees. this coolness of the climate is sometimes the more surprising, as very great heat is felt at carthago (in the province of popayan); at tomependa, on the bank of the river amazon, and in the valleys of aragua, to the west of caracas; though the absolute height of these different places is between and toises. in plains as well as on mountains the isothermal lines (lines of similar heat) are not constantly parallel to the equator, or the surface of the globe. it is the grand problem of meteorology to determine the inflections of these lines, and to discover, amid modifications produced by local causes, the constant laws of the distribution of heat. the port of cumana is only seven nautical leagues from cumanacoa. it scarcely ever rains in the first-mentioned place, while in the latter there are seven months of wintry weather. at cumanacoa, the dry season begins at the winter solstice, and lasts till the vernal equinox. light showers are frequent in the months of april, may, and june. the dry weather then returns again, and lasts from the summer solstice to the end of august. then come the real winter rains, which cease only in the month of november, and during which torrents of water pour down from the skies. it was during the winter season that we took up our first abode in the missions. every night a thick fog covered the sky, and it was only at intervals that i succeeded in taking some observations of the stars. the thermometer kept from . to degrees, which under this zone, and to the sensations of a traveller coming from the coasts, appears a great degree of coolness. i never perceived the temperature in the night at cumana below degrees. the greatest heat is felt from noon to o'clock, the thermometer keeping between and degrees. the maximum of the heat, about two hours after the passage of the sun over the meridian, was very regularly marked by a storm which murmured near. large black and low clouds dissolved in rain, which came down in torrents: these rains lasted two or three hours, and lowered the thermometer five or six degrees. about five o'clock the rain entirely ceased, the sun reappeared a little before it set, and the hygrometer moved towards the point of dryness; but at eight or nine we were again enveloped in a thick stratum of vapour. these different changes follow successively, we were assured, during whole months, and yet not a breath of wind is felt. comparative experiments led us to believe that in general the nights at cumanacoa are from two to three, and the days from four to five centesimal degrees cooler than at the port of cumana. these differences are great; and if, instead of meteorological instruments, we consulted only our own feelings, we should suppose they were still more considerable. the vegetation of the plain which surrounds the town is monotonous, but, owing to the extreme humidity of the air, remarkable for its freshness. it is chiefly characterized by an arborescent solanum, forty feet in height, the urtica baccifera, and a new species of the genus guettarda.* (* these trees are surrounded by galega pilosa, stellaria rotundifolia, aegiphila elata of swartz, sauvagesia erecta, martinia perennis, and a great number of rivinas. we find among the gramineous plants, in the savannah of cumanacoa, the paspalus lenticularis, panicum ascendens, pennisetum uniflorum, gynerium saccharoides, eleusine indica, etc.) the ground is very fertile, and might be easily watered if trenches were cut from a great number of rivulets, the springs of which never dry up during the whole year. the most valuable production of the district is tobacco. since the introduction of the farm* (* estanco real de tabaco, royal monopoly of tobacco.) in , the cultivation of tobacco in the province of cumana is nearly confined to the valley of cumanacoa; as in mexico it is permitted only in the two districts of orizaba and cordova. the farm system is a monopoly odious to the people. all the tobacco that is gathered must be sold to government; and to prevent, or rather to diminish fraud, it has been found most easy to concentrate the cultivation in one point. guards scour the country, to destroy any plantations without the boundaries of the privileged districts; and to inform against those inhabitants who smoke cigars prepared by their own hands. next to the tobacco of the island of cuba and of the rio negro, that of cumana is the most aromatic. it excels all the tobacco of new spain and of the province of varinas. we shall give some particulars of its culture, which essentially differs from the method practised in virginia. the prodigious expansion which is remarked in the solaneous plants of the valley of cumanacoa, especially in the abundant species of the solanum arborescens, of aquartia, and of cestrum, seems to indicate the favourable nature of this spot for plantations of tobacco. the seed is sown in the open ground, at the beginning of september; though sometimes not till the month of december, which period is however less favourable for the harvest. the cotyledons appear on the eighth day, and the young plants are covered with large leaves of heliconia and plantain, and shelter them from the direct action of the sun. great care also is taken to destroy weeds, which, between the tropics, spring up with astonishing rapidity. the tobacco is transplanted into a rich and well-prepared soil, a month or two after it has risen from the seed. the plants are disposed in regular rows, three or four feet distant from each other. care is taken to weed them often, and the principal stalk is several times topped, till greenish blue spots indicate to the cultivator the maturity of the leaves. they begin to gather them in the fourth month, and this first gathering generally terminates in the space of a few days. it would be better if the leaves were plucked only as they dry. in good years the cultivators cut the plant when it is only four feet high; and the shoot which springs from the root, throws out new leaves with such rapidity that they may be gathered on the thirteenth or fourteenth day. these last have the cellular tissue very much extended, and they contain more water, more albumen and less of that acrid, volatile principle, which is but little soluble in water, and in which the stimulant property of tobacco seems to reside. at cumanacoa the tobacco, after being gathered, undergoes a preparation which the spaniards call cura seca. the leaves are suspended by threads of cocuiza;* (* agave americana.) their ribs are taken out, and they are twisted into cords. the prepared tobacco should be carried to the king's warehouses in the month of june; but the indolence of the inhabitants, and the preference they give to the cultivation of maize and cassava, usually prevent them from finishing the preparation before the month of august. it is easy to conceive that the leaves, so long exposed to very moist air, must lose some of their flavour. the administrator of the farm keeps the tobacco deposited in the king's warehouses sixty days without touching it. when this time is expired, the manoques are opened to examine the quality. if the administrator find the tobacco well prepared, he pays the cultivator three piastres for the aroba of twenty-five pounds weight. the same quantity is resold for the king's profit at twelve piastres and a half. the tobacco that is rotten (podrido), that is, again gone into a state of fermentation, is publicly burnt; and the cultivator, who has received money in advance from the royal farm, loses irrevocably the fruits of his long labour. we saw heaps, amounting to five hundred arobas, burnt in the great square, which in europe might have served for making snuff. the soil of cumanacoa is so favourable to this branch of culture, that tobacco grows wild, wherever the seed finds any moisture. it grows thus spontaneously at cerro del cuchivano, and around the cavern of caripe. the only kind of tobacco cultivated at cumanacoa, as well as in the neighbouring districts of aricagua and san lorenzo, is that with large sessile leaves,* (* nicotiana tabacum.) called virginia tobacco. the tobacco with petiolate leaves,* (* nicotiana rustica.) which is the yetl of the ancient mexicans, is unknown. in studying the history of our cultivated plants, we are surprised to find that, before the conquest, the use of tobacco was spread through the greater part of america, while the potato was unknown both in mexico and the west india islands, where it grows well in the mountainous regions. tobacco has also been cultivated in portugal since the year , though the potato did not become an object of european agriculture till the end of the seventeenth and beginning of the eighteenth century. this latter plant, which has had so powerful an influence on the well-being of society, has spread in both continents more slowly than tobacco, which can be considered only as an article of luxury. next to tobacco, the most important culture of the valley of cumanacoa is that of indigo. the manufacturers of cumanacoa, of san fernando, and of arenas, produce indigo of greater commercial value than that of caracas; and often nearly equalling in splendour and richness of colour the indigo of guatimala. it was from that province that the coasts of cumana received the first seeds of the indigofera anil,* which is cultivated jointly with the indigofera tinctoria. (* the indigo known in commerce is produced by four species of plants; the indigofera tinctoria, i. anil, i. argentea, and i. disperma. at the rio negro, near the frontiers of brazil, we found the i. argentea growing wild, but only in places anciently inhabited by indians.) the rains being very frequent in the valley of cumanacoa, a plant of four feet high yields no more colouring matter than one of a third part that size in the arid valleys of aragua, to the west of the town of caracas. the manufactories we examined are all built on uniform principles. two steeping vessels, or vats, which receive the plants intended to be brought into a state of fermentation, are joined together. each vat is fifteen feet square, and two and a half deep. from these upper vats the liquor runs into beaters, between which is placed the water-mill. the axletree of the great wheel crosses the two beaters. it is furnished with ladles, fixed to long handles, adapted for the beating. from a spacious settling-vat, the colouring fecula is carried to the drying place, and spread on planks of brasiletto, which, having small wheels, can be sheltered under a roof in case of sudden rains. sloping and very low roofs give the drying place the appearance of hot-houses at some distance. in the valley of cumanacoa, the fermentation of the plant is produced with astonishing rapidity. it lasts in general but four or five hours. this short duration can be attributed only to the humidity of the climate, and the absence of the sun during the development of the plant. i think i have observed, in the course of my travels, that the drier the climate, the slower the vat works, and the greater the quantity of indigo, at the minimum of oxidation, contained in the stalks. in the province of caracas, where cubic feet of the plant slightly piled up yield thirty-five or forty pounds of dry indigo, the liquid does not pass into the beater till after twenty, thirty, or thirty-five hours. it is probable that the inhabitants of cumanacoa would extract more colouring matter if they left the plants longer steeping in the first vat.* (* the planters are pretty generally of opinion, that the fermentation should never continue less than ten hours. beauvais-raseau, art de l'indigotier page .) during my abode at cumana i made solutions of the indigo of cumanacoa, which is somewhat heavy and coppery, and that of caracas, in sulphuric acid, in order to compare them, and the solution of the former appeared to me to be of a much more intense blue. the plain of cumanacoa, spotted with farms and small plantations of indigo and tobacco, is surrounded with mountains, which towards the south rise to considerable height. everything indicates that the valley is the bottom of an ancient lake. the mountains, which in ancient times formed its shores, all rise perpendicularly in the direction of the plain. the only outlet for the waters of the lake was on the side of arenas. in digging foundations, beds of round pebbles, mixed with small bivalve shells, are found; and according to the report of persons worthy of credit, there were discovered, thirty years ago, at the bottom of the ravine of san juanillo, two enormous femoral bones, four feet long, and weighing more than thirty pounds. the indians imagined that these were giants' bones; whilst the half-learned sages of the country, who assume the right of explaining everything, gravely asserted that they were mere sports of nature, and little worthy of attention; an opinion founded on the circumstance that human bones decay rapidly in the soil of cumanacoa. in order to decorate their churches on the festival of the dead, they take skulls from the cemeteries on the coast, where the earth is impregnated with saline substances. these pretended thigh-bones of giants were carried to the port of cumana, where i sought for them in vain; but from the analogy of some fossil bones which i brought from other parts of south america, and which have been carefully examined by m. cuvier, it is probable that the gigantic femoral bones of cumanacoa belonged to elephants of a species now extinct. it may appear surprising that they were found in a place so little elevated above the present level of the waters; since it is a remarkable fact, that the fragments of the mastodons and fossil elephants which i brought from the equinoctial regions of mexico, new grenada, quito, and peru, were not found in low regions (as were the megatherium of rio luxan* (* one league south-east from the town of buenos ayres.) and virginia,* (* the megatherium of virginia is the megalonyx of mr. jefferson. all the enormous remains found in the plains of the new continent, either north or south of the equator, belong, not to the torrid, but to the temperate zone. on the other hand, pallas observes that in siberia, consequently also northward of the tropics, fossil bones are never found in mountainous parts. these facts, intimately connected together, seem calculated to lead to the discovery of a great geological law.) the great mastodons of the ohio, and the fossil elephants of the susquehanna, in the temperate zone), but on table-lands having from six to fourteen hundred toises of elevation. as we approached the southern bank of the basin of cumanacoa, we enjoyed the view of the turimiquiri.* (* some of the inhabitants pronounce this name tumuriquiri, others turumiquiri, or tumiriquiri. during the whole time of our stay at cumanacoa, the summit of this mountain was covered with clouds. it appeared uncovered on the evening of the th of september, but only for a few minutes. the angle of elevation, taken from the great square of cumanacoa, was degrees minutes. this determination, and the barometrical measurement which i made on the th, may enable us to fix, within a certain approximation, the distance of the mountain at six miles and a third, or toises; admitting that the part uncovered by clouds was toises above the plain of cumanacoa.) an enormous wall of rocks, the remains of an ancient cliff, rises in the midst of the forests. farther to the west, at cerro del cuchivano, the chain of mountains seems as if broken by the effects of an earthquake. the crevice is more than a hundred and fifty toises wide, is surrounded by perpendicular rocks, and is filled with trees, the interwoven branches of which find no room to spread. this cleft appears like a mine opened by the falling in of the earth. it is intersected by a torrent, the rio juagua, and its appearance is highly picturesque. it is called risco del cuchivano. the river rises at the distance of seven leagues south-west, at the foot of the mountain of the brigantine, and it forms some beautiful cascades before it spreads through the plain of cumanacoa. we visited several times a small farm, the conuco of bermudez, opposite the risco del cuchivano, where tobacco, plantains, and several species of cotton-trees,* are cultivated in the moist soil (* gossypium uniglandulosum, improperly called herbaceum, and g. barbadense.); especially that tree, the cotton of which is of a nankeen colour, and which is so common in the island of margareta.* (* g. religiosum.) the proprietor of the farm told us that the risco or crevice was inhabited by jaguar tigers. these animals pass the day in caverns, and roam around human habitations at night. being well fed, they grow to the length of six feet. one of them had devoured, in the preceding year, a horse belonging to the farm. he dragged his prey on a fine moonlight night, across the savannah, to the foot of a ceiba* of an enormous size. (* bombax ceiba: five-leaved silk-cotton tree.) the groans of the dying horse awoke the slaves of the farm, who went out armed with lances and machetes.* (* great knives, with very long blades, like a couteau de chasse. no one enters the woods in the torrid zone without being armed with a machete, not only to cut his way through the woods, but as a defence against wild beasts.) the tiger, crouching over his prey, awaited their approach with tranquillity, and fell only after a long and obstinate resistance. this fact, and many others verified on the spot, prove that the great jaguar* of terra firma (* felis onca, linn., which buffon called panthere oillee, and which he believed came from africa.), like the jaguarete of paraguay, and the real tiger of asia, does not flee from man when it is dared to close combat, and when not intimidated by the number of its assailants. naturalists at present admit that buffon was entirely mistaken with respect to the greatest of the feline race of america. what buffon says of the cowardice of tigers of the new continent, relates to the small ocelots.* (* felis pardalis, linn., or the chibiguazu of azara, different from the tlateo-ocelotl, or tiger-cat of the aztecs.) at the orinoco, the real jaguar of america sometimes leaps into the water, to attack the indians in their canoes. opposite the farm of bermudez, two spacious caverns open into the crevice of cuchivano, whence at times there issue flames, which may be seen at a great distance in the night; and, judging by the elevation of the rocks, above which these fiery exhalations ascend, we should be led to think that they rise several hundred feet. this phenomenon was accompanied by a subterranean, dull, and long continued noise, at the time of the last great earthquake of cumana. it is observed chiefly during the rainy season; and the owners of the farms opposite the mountain of cuchivano allege that the flames have become more frequent since december . in a herborizing excursion we made at rinconada we attempted to penetrate into the crevice, wishing to examine the rocks which seemed to contain in their bosom the cause of these extraordinary conflagrations; but the strength of the vegetation, the interweaving of the lianas, and thorny plants, hindered our progress. happily the inhabitants of the valley themselves felt a warm interest in our researches, less from the fear of a volcanic explosion, than because their minds were impressed with the idea that the risco del cuchivano contained a gold mine; and although we expressed our doubts of the existence of gold in a secondary limestone, they insisted on knowing "what the german miner thought of the richness of the vein." ever since the time of charles v and the government of the welsers, the alfingers, and the sailers, at coro and caracas, the people of terra firma have entertained a great confidence in the germans with respect to all that relates to the working of mines. wherever i went in south america, when the place of my birth was known, i was shown samples of ore. in these colonies every frenchman is supposed to be a physician, and every german a miner. the farmers, with the aid of their slaves, opened a path across the woods to the first fall of the rio juagua; and on the th of september we made our excursion to the cuchivano. on entering the crevice we recognised the proximity of tigers by a porcupine recently emboweled. for greater security the indians returned to the farm, and brought back some dogs of a very small breed. we were assured that in the event of our meeting a jaguar in a narrow path he would spring on the dog rather than on a man. we did not proceed along the brink of the torrent, but on the slope of the rocks which overhung the water. we walked on the side of a precipice from two to three hundred feet deep, on a kind of very narrow cornice, like the road which leads from the grindelwald along the mettenberg to the great glacier. when the cornice was so narrow that we could find no place for our feet, we descended into the torrent, crossed it by fording, and then climbed the opposite wall. these descents are very fatiguing, and it is not safe to trust to the lianas, which hang like great cords from the tops of the trees. the creeping and parasite plants cling but feebly to the branches which they embrace; the united weight of their stalks is considerable, and you run the risk of pulling down a whole mass of verdure, if, in walking on a sloping ground, you support your weight by the lianas. the farther we advanced the thicker the vegetation became. in several places the roots of the trees had burst the calcareous rock, by inserting themselves into the clefts that separate the beds. we had some trouble to carry the plants which we gathered at every step. the cannas, the heliconias with fine purple flowers, the costuses, and other plants of the amomum family, here attain eight or ten feet in height, and their fresh tender verdure, their silky gloss, and the extraordinary development of the parenchyma, form a striking contrast with the brown colour of the arborescent ferns, the foliage of which is delicately shaped. the indians made incisions with their large knives in the trunks of the trees, and fixed our attention on those beautiful red and gold-coloured woods, which will one day be sought for by our turners and cabinet-makers. they showed us a plant of the compositae order, twenty feet high (the eupatorium laevigatum of lamarck), the rose of belveria,* (* brownea racemosa.) celebrated for the brilliancy of its purple flowers, and the dragon's-blood of this country, which is a kind of croton not yet described.* (* plants of families entirely different are called in the spanish colonies of both continents, sangre de draco; they are dracaenas, pterocarpi, and crotons. father caulin descrip. corografica page , in speaking of resins found in the forests of cumana, makes a just distinction between the draco de la sierra de unare, which has pinnate leaves (pterocarpus draco), and the draco de la sierra de paria, with entire and hairy leaves. the latter is the croton sanguifluum of cumanacoa, caripe, and cariaco. ) the red and astringent juice of this plant is employed to strengthen the gums. the indians recognize the species by the smell, and more particularly by chewing the woody fibres. two natives, to whom the same wood was given to chew, pronounced without hesitation the same name. we could avail ourselves but little of the sagacity of our guides, for how could we procure leaves, flowers, and fruits growing on trunks, the branches of which commence at fifty or sixty feet high? we were struck at finding in this hollow the bark of trees, and even the soil, covered with moss* and lichens. (* real musci frondosi. we also found, besides a small boletus stipitatus, of a snow-white colour, the boletus igniarius, and the lycoperdon stellatum of europe. i had found this last only in very dry places in germany and poland.) the cryptogamous plants are here as common as in northern countries. their growth is favoured by the moisture of the air, and the absence of the direct rays of the sun. nevertheless the temperature is generally at degrees in the day, and degrees at night. the rocks which bound the crevice of cuchivano are perpendicular like walls, and are of the same calcareous formation which we observed the whole way from punta delgada. it is here a blackish grey, of compact fracture, tending sometimes towards the sandy fracture, and crossed by small veins of white carbonated lime. in these characteristic marks we thought we discovered the alpine limestone of switzerland and the tyrol, of which the colour is always deep, though in a less degree than that of the transition limestone.* (* escher, in the alpina volume page .) the first of these formations constitutes the cuchivano, the nucleus of the imposible, and in general the whole group of the mountains of new andalusia. i saw no petrifactions in it; but the inhabitants assert that considerable masses of shells are found at great heights. the same phenomenon occurs in the country about salzburg.* (* in switzerland, the solitary beds of shells, at the height of from to toises (in the jungfrauhorn, the dent de morcle, and the dent du midi), belong to transition limestone.) at the cuchivano the alpine limestone contains beds of marly clay,* (*mergelschiefer.) three or four toises thick; and this geological fact proves on the one hand the identity of the alpenkalkstein with the zechstein of thuringia, and on the other the affinity of formation existing between the alpine limestone and that of the jura.* (* the jura and the alpine limestone are kindred formations, and they are sometimes difficult to be distinguished, where they lie immediately one upon another, as in the apennines. the alpine limestone and the zechstein, famous among the geologists of freyberg, are identical formations. this identity, which i noticed in the year (uber die grubenwetter), is a geological fact the more interesting, as it seems to unite the northern european formations to those of the central chain. it is known that the zechstein is situated between the muriatiferous gypsum and the conglomerate (ancient sandstone); or where there is no muriatiferous gypsum, between the slaty sandstone with roestones (buntesandstein, wern.), and the conglomerate or ancient sandstone. it contains strata of schistous and coppery marl (bituminoce mergel and kupferschiefer) which form an important object in the working of mines at mansfeld in saxony, near riegelsdorf in hesse, and at hasel and prausnitz, in silesia. in the southern part of bavaria (oberbaiern), i saw the alpine limestone, containing these same strata of schistous clay and marl, which, though thinner, whiter, and especially more frequent, characterize the limestone of jura. respecting the slates of blattenberg, in the canton of glaris which some mineralogists, because of their numerous impressions of fish, have long mistaken for the cupreous slates of mansfeld, they belong, according to m. von buch, to a real transition formation. all these geological data tend to prove that strata of marl, more or less mixed with carbon, are to be found in the limestone of jura, in the alpine limestone, and in the transition schists. the mixture of carbon, sulphuretted iron, and copper, appears to me to augment with the relative antiquity of the formations.) the strata of marl effervesce with acids, though silex and alumina predominate in them: they are strongly impregnated with carbon, and sometimes blacken the hands, like a real vitriolic schistus. the supposed gold mine of cuchivano, which was the object of our examination, is nothing but an excavation cut into one of those black strata of marl, which contain pyrites in abundance. the excavation is on the right bank of the river juagua, and must be approached with caution, because the torrent there is more than eight feet deep. the sulphurous pyrites are found, some massive, and others crystallized and disseminated in the rock; their colour, of a very clear golden yellow, does not indicate that they contain copper. they are mixed with fibrous sulphuret of iron,* (* haarkies.) and nodules of swinestone, or fetid carbonate of lime. the marly stratum crosses the torrent; and, as the water washes out metallic grains, the people imagine, on account of the brilliancy of the pyrites, that the torrent bears down gold. it is reported that, after the great earthquake which took place in , the waters of the juagua were so charged with gold that "men who came from a great distance, and whose country was unknown," established washing-places on the spot. they disappeared during the night, after having collected a great quantity of gold. it would be needless to show that this is a fable. pyrites dispersed in quartzose veins, crossing the mica-slate, are often auriferous, no doubt; but no analogous fact leads to the supposition that the sulphuretted iron which is found in the schistose marls of the alpine limestone, contains gold. some direct experiments, made with acids, during my abode at caracas, showed that the pyrites of cuchivano are not auriferous. our guides were amazed at my incredulity. in vain i repeated that alum and sulphate of iron only could be obtained from this supposed gold mine; they continued picking up secretly every bit of pyrites they saw sparkling in the water. in countries possessing few mines, the inhabitants entertain exaggerated ideas respecting the facility with which riches are drawn from the bowels of the earth. how much time did we not lose during five years' travels, in visiting, on the pressing invitations of our hosts, ravines, of which the pyritous strata have borne for ages the imposing names of 'minas de oro!' how often have we been grieved to see men of all classes, magistrates, pastors of villages, grave missionaries, grinding, with inexhaustible patience, amphibole, or yellow mica, in the hope of extracting gold from it by means of mercury! this rage for the search of mines strikes us the more in a climate where the ground needs only to be slightly raked to produce abundant harvests. after visiting the pyritous marls of the rio juagua, we continued following the course of the crevice, which stretches along like a narrow canal overshadowed by very lofty trees. we observed strata on the left bank, opposite cerro del cuchivano, singularly crooked and twisted. this phenomenon i had often admired at the ochsenberg, * in passing the lake of lucerne. (* this mountain of switzerland is composed of transition limestone. we find these same inflexions in the strata near bonneville, at nante d'arpenas in savoy, and in the valley of estaubee in the pyrenees. another transition rock, the grauwakke of the germans (very near the english killas), exhibits the same phenomenon in scotland.) the calcareous beds of the cuchivano and the neighbouring mountains keep pretty regularly the direction of north-north-east and south-south-west. their inclination is sometimes north and sometimes south; most commonly they seem to take a direction towards the valley of cumanacoa; and it cannot be doubted that the valley has an influence* on the inclination of the strata. (* the same observation may apply to the lake of gemunden in styria, which i visited with m. von buch, and which is one of the most picturesque situations in europe.) we had suffered great fatigue, and were quite drenched by frequently crossing the torrent, when we reached the caverns of the cuchivano. a wall of rock there rises perpendicularly to the height of eight hundred toises. it is seldom that in a zone where the force of vegetation everywhere conceals the soil and the rocks, we behold a great mountain presenting naked strata in a perpendicular section. in the middle of this section, and in a position unfortunately inaccessible to man, two caverns open in the form of crevices. we were assured that they are inhabited by nocturnal birds, the same as those we were soon to become acquainted with in the cueva del guacharo of caripe. near these caverns we saw strata of schistose marl, and found, with great astonishment, rock-crystals encased in beds of alpine limestone. they were hexahedral prisms, terminated with pyramids, fourteen lines long and eight thick. the crystals, perfectly transparent, were solitary, and often three or four toises distant from each other. they were enclosed in the calcareous mass, as the quartz crystals of burgtonna,* (* in the duchy of gotha.) and the boracite of lunebourg, are contained in gypsum. there was no crevice near, or any vestige of calcareous spar.* (* this phenomenon reminds us of another equally rare, the quartz crystals found by m. freiesleben in saxony, near burgorner, in the county of mansfeld, in the middle of a rock of porous limestone (rauchwakke), lying immediately on the alpine limestone. the rock crystals, which are pretty common in the primitive limestone of carrara, line the insides of cavities in the rocks, without being enveloped by the rock itself.) we reposed at the foot of the cavern whence those flames were seen to issue, which of late years have become more frequent. our guides and the farmer, an intelligent man, equally acquainted with the localities of the province, discussed, in the manner of the creoles, the dangers to which the town of cumanacoa would be exposed if the cuchivano became an active volcano, or, as they expressed it, "se veniesse a reventar." it appeared to them evident, that since the great earthquakes of quito and cumana in , new andalusia was every day more and more undermined by subterranean fires. they cited the flames which had been seen to issue from the earth at cumana; and the shocks felt in places where heretofore the ground had never been shaken. they recollected that at macarapan, sulphurous emanations had been frequently perceived for some months past. we were struck with these facts, upon which were founded predictions that have since been almost all realized. enormous convulsions of the earth took place at caracas in , and proved how tumultuously nature is agitated in the north-east part of terra firma. but what is the cause of the luminous phenomena which are observed in the cuchivano? the column of air which rises from the mouth of a burning volcano* is sometimes observed to shine with a splendid light. (* we must not confound this very rare phenomenon with the glimmering commonly observed a few toises above the brink of a crater, and which (as i remarked at mount vesuvius in ) is only the reflection of great masses of inflamed scoria, thrown up without sufficient force to pass the mouth of the volcano.) this light, which is believed to be owing to the hydrogen gas, was observed from chillo, on the summit of the cotopaxi, at a time when the mountain seemed in the greatest repose. according to the statements of the ancients, the mons albanus, near rome, known at present under the name of monte cavo, appeared at times on fire during the night; but the mons albanus is a volcano recently extinguished, which, in the time of cato, threw out rapilli;* (* "albano monte biduum continenter lapidibus pluit."--livy lib. cap. . (heyne, opuscula acad. tome page .)) while the cuchivano is a calcareous mountain, remote from any trap formation. can these flames be attributed to the decomposition of water, entering into contact with the pyrites dispersed through the schistose marl? or is it inflamed hydrogen that issues from the cavern of cuchivano? the marls, as the smell indicates, are pyritous and bituminous at the same time; and the petroleum springs at the buen pastor, and in the island of trinidad, proceed probably from these same beds of alpine limestone. it would be easy to suppose some connexion between the waters filtering through this calcareous stone, and decomposed by pyrites and the earthquakes of cumana, the springs of sulphuretted hydrogen in new barcelona, the beds of native sulphur at carupano, and the emanations of sulphurous acid which are perceived at times in the savannahs. it cannot be doubted also, that the decomposition of water by the pyrites at an elevated temperature, favoured by the affinity of oxidated iron for earthy substances, may have caused that disengagement of hydrogen gas, to the action of which several modern geologists have attributed so much importance. but in general, sulphurous acid is perceived more commonly than hydrogen in the eruption of volcanoes, and the odour of that acid principally prevails while the earth is agitated by violent shocks. when we take a general view of the phenomena of volcanoes and earthquakes, when we recollect the enormous distance at which the commotion is propagated below the basin of the sea, we readily discard explanations founded on small strata of pyrites and bituminous marls. i am of opinion that the shocks so frequently felt in the province of cumana are as little to be attributed to the rocks above the surface of the earth, as those which agitate the apennines are assignable to asphaltic veins or springs of burning petroleum. the whole of these phenomena depend on more general, i would almost say on deeper, causes; and it is not in the secondary strata which form the exterior crust of our globe, but in the primitive rocks, at an enormous distance from the soil, that we should seek the focus of volcanic action. the greater progress we make in geology, the more we feel the insufficiency of theories founded on observations merely local. on the th of september we continued our journey to the convent of caripe, the principal settlement of the chayma missions. we chose, instead of the direct road, that by the mountains of the cocollar* (* is this name of indian origin? at cumana i heard it derived in a manner somewhat far-fetched from the spanish word cogollo, signifying the heart of oleraceous plants. the cocollar forms the centre of the whole group of the mountains of new andalusia.) and the turimiquiri, the height of which little exceeds that of jura. the road first runs eastward, crossing over the length of three leagues the table-land of cumanacoa, in a soil formerly levelled by the waters: it then turns to the south. we passed the little indian village of aricagua surrounded by woody hills. thence we began to ascend, and the ascent lasted more than four hours. we crossed two-and-twenty times the river of pututucuar, a rapid torrent, full of blocks of calcareous rock. when, on the cuesta del cocollar, we reached an elevation two thousand feet above the level of the sea, we were surprised to find scarcely any forests or great trees. we passed over an immense plain covered with gramineous plants. mimosas with hemispheric tops, and stems only four or five feet high, alone vary the dull uniformity of the savannahs. their branches are bent towards the ground or spread out like umbrellas. wherever there are deep declivities, or masses of rocks half covered with mould, the clusia or cupey, with great nymphaea flowers, displays its beautiful verdure. the roots of this tree are eight inches in diameter, and they sometimes shoot out from the trunk at the height of fifteen feet above the soil. after having climbed the mountain for a considerable time, we reached a small plain at the hato del cocollar. this is a solitary farm, situated on a table-land toises high. we rested three days in this retreat, where we were treated with great kindness by the proprietor, don mathias yturburi, a native of biscay, who had accompanied us from the port of cumana. we there found milk, excellent meat from the richness of the pasture, and above all, a delightful climate. during the day the centigrade thermometer did not rise above or degrees; a little before sunset it fell to , and at night it scarcely kept up to degrees.* (* . degrees reaum.) the nightly temperature was consequently seven degrees colder than that of the coasts, which is a fresh proof of an extremely rapid decrement of heat, the table-land of cocollar being less elevated than the site of the town of caracas. as far as the eye could reach, we perceived, from this elevated point, only naked savannahs. small tufts of scattered trees rise in the ravines; and notwithstanding the apparent uniformity of vegetation, great numbers of curious plants* are found here. (* cassia acuta, andromeda rigida, casearia hypericifolia, myrtus longifolia, buettneria salicifolia, glycine picta, g. pratensis, g. gibba, oxalis umbrosa, malpighia caripensis, cephaelis salicifolia, stylosanthes angustifolia, salvia pseudococcinea, eryngium foetidum. we found a second time this last plant, but at a considerable height, in the great forests of bark trees surrounding the town of loxa, in the centre of the cordilleras.) we shall only speak of a superb lobelia* with purple flowers (* lobelia spectabilis.); the brownea coccinea, which is upwards of a hundred feet high; and above all; the pejoa, celebrated in the country on account of the delightful and aromatic perfume emitted by its leaves when rubbed between the fingers.* (* it is the gualtheria odorata. the pejoa is found round the lake of cocollar, which gives birth to the great river guarapiche. we met with the same shrub at the cuchilla de guanaguana. it is a subalpine plant, which forms at the silla de caracas a zone much higher than in the province of cumana. the leaves of the pejoa have even a more agreeable smell than those of the myrtus pimenta, but they yield no perfume when rubbed a few hours after their separation from the tree.) but the great charms of this solitary place were the beauty and serenity of the nights. the proprietor of the farm, who spent his evenings with us, seemed to enjoy the astonishment produced on europeans newly transplanted to the tropics, by that vernal freshness of the air which is felt on the mountains after sunset. in those distant regions, where men yet feel the full value of the gifts of nature, a land-holder boasts of the water of his spring, the absence of noxious insects, the salutary breeze that blows round his hill, as we in europe descant on the conveniences of our dwellings, and the picturesque effect of our plantations. our host had visited the new world with an expedition which was to form establishments for felling wood for the spanish navy on the shores of the gulf of paria. in the vast forests of mahogany, cedar, and brazil-wood, which border the caribbean sea, it was proposed to select the trunks of the largest trees, giving them in a rough way the shape adapted to the building of ships, and sending them every year to the dockyard near cadiz. white men, unaccustomed to the climate, could not support the fatigue of labour, the heat, and the effect of the noxious air exhaled by the forests. the same winds which are loaded with the perfume of flowers, leaves, and woods, infuse also, as we may say, the germs of dissolution into the vital organs. destructive fevers carried off not only the ship-carpenters, but the persons who had the management of the establishment; and this bay, which the early spaniards named golfo triste (melancholy bay), on account of the gloomy and wild aspect of its coasts, became the grave of european seamen. our host had the rare good fortune to escape these dangers. after having witnessed the death of a great number of his friends, he withdrew from the coast to the mountains of cocollar. nothing can be compared to the majestic tranquillity which the aspect of the firmament presents in this solitary region. when tracing with the eye, at night-fall, the meadows which bounded the horizon,--the plain covered with verdure and gently undulated, we thought we beheld from afar, as in the deserts of the orinoco, the surface of the ocean supporting the starry vault of heaven. the tree under which we were seated, the luminous insects flying in the air, the constellations which shone in the south; every object seemed to tell us how far we were from our native land. if amidst this exotic nature we heard from the depth of the valley the tinkling of a bell, or the lowing of herds, the remembrance of our country was awakened suddenly. the sounds were like distant voices resounding from beyond the ocean, and with magical power transporting us from one hemisphere to the other. strange mobility of the imagination of man, eternal source of our enjoyments and our pains! we began in the cool of the morning to climb the turimiquiri. this is the name given to the summit of the cocollar, which, with the brigantine, forms one single mass of mountain, formerly called by the natives the sierra de los tageres. we travelled along a part of the road on horses, which roam about these savannahs; but some of them are used to the saddle. though their appearance is very heavy, they pass lightly over the most slippery turf. we first stopped at a spring issuing, not from the calcareous rock, but from a layer of quartzose sandstone. the temperature was degrees, consequently . degrees less than the spring of quetepe; and the difference of the level is nearly toises. wherever the sandstone appears above ground the soil is level, and constitutes as it were small platforms, succeeding each other like steps. to the height of toises, and even beyond, this mountain, like those in its vicinity, is covered only with gramineous plants.* (* the most abundant species are the paspalus; the andropogon fastigiatum, which forms the genus diectomis of m. palissot de beauvais; and the panicum olyroides.) the absence of trees is attributed at cumana to the great elevation of the ground; but a slight reflection on the distribution of plants in the cordilleras of the torrid zone will lead us to conceive that the summits of new andalusia are very far from reaching the superior limit of the trees, which in this latitude is at least toises of absolute height. the smooth turf of the cocollar begins to appear at toises above the level of the sea, and the traveller may contrive to walk upon this turf till he reaches a thousand toises in height. farther on, beyond this band covered with gramineous plants, we found, amidst peaks almost inaccessible to man, a small forest of cedrela, javillo,* (* huras crepitans, of the family of the euphorbias. the growth of its trunk is so enormous, that m. bonpland measured vats of javillo wood, feet long and wide. these vats, made from one log of wood, are employed to keep the guarapo, or juice of the sugar-cane, and the molasses. the seeds of javillo are a very active poison, and the milk that issues from the petioles, when broken, frequently produced inflammation in our eyes, if by chance the least quantity penetrated under the eyelids.) and mahogany. these local circumstances induce me to think that the mountainous savannahs of the cocollar and turimiquiri owe their existence only to the destructive custom practised by the natives of setting fire to the woods when they want to convert the soil into pasturage. where, during the lapse of three centuries, grasses and alpine plants have covered the soil with a thick carpet, the seeds of trees can no longer germinate and fix themselves in the earth, though birds and winds convey them continually from the distant forests into the savannahs. the climate of these mountains is so mild that at the farm of the cocollar the cotton and coffee tree, and even the sugar cane, are cultivated with success. whatever the inhabitants of the coasts may allege, hoar-frost has never been found in the latitude of degrees, on heights scarcely exceeding those of the mont d'or, or the puy-de-dome. the pastures of turimiquiri become less rich in proportion to the elevation. wherever scattered rocks afford shade, lichens and some european mosses are found. the melastoma guacito,* (* melastoma xanthostachys, called guacito at caracas.) and a shrub, the large and tough leaves of which rustle like parchment* when shaken by the winds, (* palicourea rigida, chaparro bovo. in the savannahs, or llanos, the same castilian name is given to a tree of the family of the proteaceae.) rise here and there in the savannah. but the principal ornament of the turf of these mountains is a liliaceous plant with golden flowers, the marica martinicensis. it is generally observed in the province of cumana and caracas only at or toises of elevation.* (* for example, in the montana de avila, on the road from caracas to la guayra, and in the silla de caracas. the seeds of the marica are ripe at the end of december.) the whole rocky mass of the turimiquiri is composed of an alpine limestone, like that of cumanacoa, and a pretty thin strata of marl and quartzose sandstone. the limestone contains masses of brown oxidated iron and carbonate of iron. i have observed in several places, and very distinctly, that the sandstone not only reposes on the limestone, but that this last rock frequently includes and alternates with the sandstone. we distinguished clearly the round summit of the turimiquiri and the lofty peaks or, as they are called, the cucuruchos, covered with thick vegetation, and infested by tigers which are hunted for the beauty of their skin. this round summit, which is covered with turf, is toises above the level of the ocean. a ridge of steep rocks stretches out westward, and is broken at the distance of a mile by an enormous crevice that descends toward the gulf of cariaco. at the point which might be supposed to be the continuation of the ridge, two calcareous paps or peaks arise, the most northern of which is the loftiest. it is this last which is more particularly called the cucurucho de turimiquiri, and which is considered to be higher than the mountain of the brigantine, so well known by the sailors who frequent the coasts of cumana. we measured, by angles of elevation, and a basis, rather short, traced on the round summit, the peak of cucurucho, which was about toises higher than our station, so that its absolute height exceeded toises. the view we enjoyed on the turimiquiri is of vast extent, and highly picturesque. from the summer to the ocean we perceived chains of mountains extended in parallel lines from east to west, and bounding longitudinal valleys. these valleys are intersected at right angles by an infinite number of small ravines, scooped out by the torrents: the consequence is, that the lateral ranges are transformed into so many rows of paps, some round and others pyramidal. the ground in general is a gentle slope as far as the imposible; farther on the precipices become bold, and continue so to the shore of the gulf of cariaco. the form of this mass of mountains reminded us of the chain of the jura; and the only plain that presents itself is the valley of cumanacoa. we seemed to look down into the bottom of a funnel, in which we could distinguish, amidst tufts of scattered trees, the indian village of aricagua. towards the north, a narrow slip of land, the peninsula of araya, formed a dark stripe on the sea, which, being illumined by the rays of the sun, reflected a strong light. beyond the peninsula the horizon was bounded by cape macanao, the black rocks of which rise amid the waters like an immense bastion. the farm of the cocollar, situated at the foot of the turimiquiri, is in latitude degrees minutes seconds. i found the dip of the needle . degrees. the needle oscillates times in ten minutes. possibly masses of brown iron-ore, included in the calcareous rock, caused a slight augmentation in the intensity of the magnetic forces. on the th of september we descended the cocollar, toward the mission of san antonio. after crossing several savannahs strewed with large blocks of calcareous stone, we entered a thick forest. having passed two ridges of extremely steep mountains,* (* these ridges, which are rather difficult to climb towards the end of the rainy season, are distinguished by the names of los yepes and fantasma.) we discovered a fine valley five or six leagues in length, pretty uniformly following the direction of east and west. in this valley are situated the missions of san antonio and guanaguana; the first is famous on account of a small church with two towers, built of brick, in pretty good style, and ornamented with columns of the doric order. it is the wonder of the country. the prefect of the capuchins completed the building of this church in less than two summers, though he employed only the indians of his village. the mouldings of the capitals, the cornices, and a frieze decorated with suns and arabesques, are executed in clay mixed with pounded brick. if we are surprised to find churches in the purest grecian style on the confines of lapland,* (* at skelefter, near torneo.--buch, voyage en norwege.) we are still more struck with these first essays of art, in a region where everything indicates the wild state of man, and where the basis of civilization has not been laid by europeans more than forty years. i stopped at the mission of san antonio only to open the barometer, and to take a few altitudes of the sun. the elevation of the great square above cumana is toises. after having crossed the village, we forded the rivers colorado and guarapiche, both of which rise in the mountains of the cocollar, and blend their waters lower down towards the east. the colorado has a very rapid current, and becomes at its mouth broader than the rhine. the guarapiche, at its junction with the rio areo, is more than twenty-five fathoms deep. its banks are ornamented by a superb gramen, of which i made a drawing two years afterward on ascending the river magdalena. the distich-leaved stalk of this gramen often reaches the height of fifteen or twenty feet.* (* lata, or cana brava. it is a new genus, between aira and arundo. this colossal gramen looks like the donax of italy. this, the arundinaria of the mississippi, (ludolfia, willd., miegia of persoon,) and the bamboos, are the highest gramens of the new continent. its seed has been carried to st. domingo, where its stalk is employed to thatch the negroes' huts.) towards evening we reached the mission of guanaguana, the site of which is almost on a level with the village of san antonio. the missionary received us cordially; he was an old man, and he seemed to govern his indians with great intelligence. the village has existed only thirty years on the spot it now occupies. before that time it was more to the south, and was backed by a hill. it is astonishing with what facility the indians are induced to remove their dwellings. there are villages in south america which in less than half a century have thrice changed their situation. the native finds himself attached by ties so feeble to the soil he inhabits, that he receives with indifference the order to take down his house and to rebuild it elsewhere. a village changes its situation like a camp. wherever clay, reeds, and the leaves of the palm or heliconia are found, a house is built in a few days. these compulsory changes have often no other motive than the caprice of a missionary, who, having recently arrived from spain, fancies that the situation of the mission is feverish, or that it is not sufficiently exposed to the winds. whole villages have been transported several leagues, merely because the monk did not find the prospect from his house sufficiently beautiful or extensive. guanaguana has as yet no church. the old monk, who during thirty years had lived in the forests of america, observed to us that the money of the community, or the produce of the labour of the indians, was employed first in the construction of the missionary's house, next in that of the church, and lastly in the clothing of the indians. he gravely assured us that this order of things could not be changed on any pretence, and that the indians, who prefer a state of nudity to the slightest clothing, are in no hurry for their turn in the destination of the funds. the spacious abode of the padre had just been finished, and we had remarked with surprise, that the house, the roof of which formed a terrace, was furnished with a great number of chimneys that looked like turrets. this, our host told us, was done to remind him of a country dear to his recollection, and to picture to his mind the winters of aragon amid the heat of the torrid zone. the indians of guanaguana cultivate cotton for their own benefit as well as for that of the church and the missionary. the natives have machines of a very simple construction to separate the cotton from the seeds. these are wooden cylinders of extremely small diameter, within which the cotton passes, and which are made to turn by a treadle. these machines, however imperfect, are very useful, and they begin to be imitated in other missions. the soil of guanaguana is not less fertile than that of aricagua, a small neighbouring village, which has also preserved its ancient indian name. an almuda of land, square toises, produces in abundant years from to fanegas of maize, each fanega weighing pounds. but here, as in other places, where the bounty of nature retards industry, a very small number of acres are cleared, and the culture of alimentary plants is neglected. scarcity of subsistence is felt, whenever the harvest is lost by a protracted drought. the indians of guanaguana related to us as a fact not uncommon, that in the preceding year they, their wives, and their children, had been for three months al monte; by which they meant, wandering in the neighbouring forests, to live on succulent plants, palm-cabbages, fern roots, and fruits of wild trees. they did not speak of this nomad life as of a state of privation. the beautiful valley of guanaguana stretches towards the east, opening into the plains of punzera and terecen. we wished to visit those plains, and examine the springs of petroleum, lying between the river guarapiche and the rio areo; but the rainy season had already arrived, and we were in daily perplexity how to dry and preserve the plants we had collected. the road from guanaguana to the village of punzera runs either by san felix or by caycara and guayuta, which is a farm for cattle (hato) of the missionaries. in this last place, according to the report of the indians, great masses of sulphur are found, not in a gypseous or calcareous rock, but at a small depth below the soil, in a bed of clay. this singular phenomenon appears to me peculiar to america; we found it also in the kingdom of quito, and in new spain. on approaching punzera, we saw in the savannahs small bags, formed of a silky tissue suspended from the branches of the lowest trees. it is the seda silvestre, or wild silk of the country, which has a beautiful lustre, but is very rough to the touch. the phalaena which produces it is probably analogous with that of the provinces of gua[?]uato and antioquia, which also furnish wild silk. we found in the beautiful forest of punzera two trees known by the names of curucay and canela; the former, of which we shall speak hereafter, yields a resin very much sought after by the piaches, or indian sorcerers; the leaves of the latter have the smell of the real cinnamon of ceylon.* (* is this the laurus cinnamomoides of mutis? what is that other cinnamon tree which the indians call tuorco, common in the mountains of tocayo, and at the sources of the rio uchere, the bark of which is mixed with chocolate? father caulin gives the name of curucay to the copaifera officinalis, which yields the balsam of capivi.--hist. corograf., pages and .) from punzera the road leads by terecin and nueva palencia, (a new colony of canarians,) to the port of san juan, situated on the right bank of the river areo; and it is only by crossing this river in a canoe, that the traveller can arrive at the famous petroleum springs (or mineral tar) of the buen pastor. they were described to us as small wells or funnels, hollowed out by nature in a marshy soil. this phenomenon reminded us of the lake of asphaltum, or of chopapote, in the island of trinidad,* (* laguna de la brea, south-east of the port of naparima. there is another spring of asphaltum on the eastern coast of the island, in the bay of mayaro.) which is distant from the buen pastor, in a straight line, only thirty-five sea leagues. having long struggled to overcome the desire we felt to descend the guarapiche to the golfo triste, we took the direct road to the mountains. the valleys of guanaguana and caripe are separated by a kind of dyke, or calcareous ridge, well known by the name of the cuchilla* de guanaguana. (* literally "blade of a knife". throughout all spanish america the name of "cuchilla" is given to the ridge of a mountain terminated on each side by very steep declivities.) we found this passage difficult, because at that time we had not climbed the cordilleras; but it is by no means so dangerous as the people at cumana love to represent it. the path is indeed in several parts only fourteen or fifteen inches broad; and the ridge of the mountain, along which the road runs, is covered with a short slippery turf. the slopes on each side are steep, and the traveller, should he stumble, might slide down to the depth of seven or eight hundred feet. nevertheless, the flanks of the mountain are steep declivities rather than precipices; and the mules of this country are so sure-footed that they inspire the greatest confidence. their habits are identical with those of the beasts of burden in switzerland and the pyrenees. in proportion as a country is wild, the instinct of domestic animals improves in address and sagacity. when the mules feel themselves in danger, they stop, turning their heads to the right and to the left; and the motion of their ears seems to indicate that they reflect on the decision they ought to take. their resolution is slow, but always just, if it be spontaneous; that is to say, if it be not thwarted or hastened by the imprudence of the traveller. on the frightful roads of the andes, during journeys of six or seven months across mountains furrowed by torrents, the intelligence of horses and beasts of burden is manifested in an astonishing manner. thus the mountaineers are heard to say, "i will not give you the mule whose step is the easiest, but the one which is most intelligent (la mas racional)." this popular expression, dictated by long experience, bears stronger evidence against the theory of animated machines, than all the arguments of speculative philosophy. when we had reached the highest point of the ridge or cuchilla of guanaguana, an interesting spectacle unfolded itself before us. we saw comprehended in one view the vast savannahs or meadows of maturin and of the rio tigre;* (* these natural meadows are part of the llanos or immense steppes bordered by the orinoco.) the peak of the turimiquiri;* (* el cucurucho.) and an infinite number of parallel ridges, which, seen at a distance, looked like the waves of the sea. on the north-east opens the valley in which is situated the convent of caripe. the aspect of this valley is peculiarly attractive, for being shaded by forests, it forms a strong contrast with the nudity of the neighbouring mountains, which are bare of trees, and covered with gramineous plants. we found the absolute height of the cuchilla to be toises. descending from the ridge by a winding path, we entered into a completely woody country. the soil is covered with moss, and a new species of drosera,* (* drosera tenella.) which by its form reminded us of the drosera of the alps. the thickness of the forests, and the force of vegetation, augmented as we approached the convent of caripe. everything here changes its aspect, even to the rock that accompanied us from punta delgada. the calcareous strata becomes thinner, forming graduated steps, which stretch out like walls, cornices, and turrets, as in the mountains of jura, those of pappenheim in germany, and near oizow in galicia. the colour of the stone is no longer of a smoky or bluish grey; it becomes white; its fracture is smooth, and sometimes even imperfectly conchoidal. it is no longer the calcareous formation of the higher alps, but a formation to which this serves as a basis, and which is analogous to the jura limestone. in the chain of the apennines, between rome and nocera, i observed this same immediate superposition.* (* in like manner, near geneva, the rock of the mole, belonging to the alpine limestone, lies under the jura limestone which forms mount saleve.) it indicates, not the transition from one rock to another, but the geological affinity existing between two formations. according to the general type of the secondary strata, recognised in a great part of europe, the alpine limestone is separated from the jura limestone by the muriatiferous gypsum; but often this latter is entirely wanting, or is contained as a subordinate layer in the alpine limestone. in this case the two great calcareous formations succeed each other immediately, or are confounded in one mass. the descent from the cuchilla is far shorter than the ascent. we found the level of the valley of caripe toises higher than that of the valley of guanaguana.* (* absolute height of the convent above the level of the sea, toises.) a group of mountains of little breadth separates two valleys, one of which is of delicious coolness, while the other is famed for the heat of its climate. these contrasts, so common in mexico, new grenada, and peru, are very rare in the north-east part of south america. thus caripe is the only one of the high valleys of new andalusia which is much inhabited. chapter . . convent of caripe. cavern of the guacharo. nocturnal birds. an alley of perseas led us to the hospital of the aragonese capuchins. we stopped near a cross of brazil-wood, erected in the midst of a square, and surrounded with benches, on which the infirm monks seat themselves to tell their rosaries. the convent is backed by an enormous wall of perpendicular rock, covered with thick vegetation. the stone, which is of resplendent whiteness, appears only here and there between the foliage. it is difficult to imagine a more picturesque spot. it recalled forcibly to my remembrance the valleys of derbyshire, and the cavernous mountains of muggendorf, in franconia. instead of the beeches and maple trees of europe we here find the statelier forms of the ceiba and the palm-tree, the praga and irasse. numberless springs gush from the sides of the rocks which encircle the basin of caripe, and of which the abrupt slopes present, towards the south, profiles of a thousand feet in height. these springs issue, for the most part, from a few narrow crevices. the humidity which they spread around favours the growth of the great trees; and the natives, who love solitary places, form their conucos along the sides of these crevices. plantains and papaw trees are grouped together with groves of arborescent fern; and this mixture of wild and cultivated plants gives the place a peculiar charm. springs are distinguished from afar, on the naked flanks of the mountains, by tufted masses of vegetation* which at first sight seem suspended from the rocks, and descending into the valley, they follow the sinuosities of the torrents.* (* among the interesting plants of the valley of caripe, we found for the first time a calidium, the trunk of which was twenty feet high (c. arboreum); the mikania micrantha, which may probably possess some of the alexipharmic properties of the famous guaco of the choco; the bauhinia obtusifolia, a very large tree, called guarapa by the indians; the weinnannia glabra; a tree psychotria, the capsules of which, when rubbed between the fingers, emit a very agreeable orange smell; the dorstenia houstoni (raiz de resfriado); the martynia craniolaria, the white flowers of which are six or seven inches long; a scrophularia, having the aspect of the verbascum miconi, and the leaves of which, all radical and hairy, are marked with silvery glands.) we were received with great hospitality by the monks of caripe. the building has an inner court, surrounded by an arcade, like the convents in spain. this enclosed place was highly convenient for setting up our instruments and making observations. we found a numerous society in the convent. young monks, recently arrived from spain, were just about to settle in the missions, while old infirm missionaries sought for health in the fresh and salubrious air of the mountains of caripe. i was lodged in the cell of the superior, which contained a pretty good collection of books. i found there, to my surprise, the teatro critico of feijoo, the lettres edifiantes, and the traite d'electricite by abbe nollet. it seemed as if the progress of knowledge advanced even in the forests of america. the youngest of the capuchin monks of the last mission had brought with him a spanish translation of chaptal's treatise on chemistry, and he intended to study this work in the solitude where he was destined to pass the remainder of his days. during our long abode in the missions of south america we never perceived any sign of intolerance. the monks of caripe were not ignorant that i was born in the protestant part of germany. furnished as i was with orders from the court of spain, i had no motives to conceal from them this fact; nevertheless, no mark of distrust, no indiscreet question, no attempt at controversy, ever diminished the value of the hospitality they exercised with so much liberality and frankness. the convent is founded on a spot which was anciently called areocuar. its height above the level of the sea is nearly the same as that of the town of caracas, or of the inhabited part of the blue mountains of jamaica. thus the mean temperatures of these three points, all situated within the tropics, are nearly the same. the necessity of being well clothed at night, and especially at sunrise, is felt at caripe. we saw the centigrade thermometer at midnight, between and . degrees; in the morning, between and degrees. about one o'clock it had risen only to , or . degrees. this temperature is sufficient for the development of the productions of the torrid zone; though, compared with the excessive heat of the plains of cumana, we might call it the temperature of spring. water exposed to currents of air in vessels of porous clay, cools at caripe, during the night, as low as degrees. experience has proved that the temperate climate and rarefied air of this spot are singularly favourable to the cultivation of the coffee-tree, which is well known to flourish on heights. the prefect of the capuchins, an active and enlightened man, has introduced into the province this new branch of agricultural industry. indigo was formerly planted at caripe, but the small quantity of fecula yielded by this plant, which requires great heat, caused the culture to be abandoned. we found in the conuco of the community many culinary plants, maize, sugar cane, and five thousand coffee-trees, which promised a fine harvest. the friars were in hopes of tripling the number in a few years. we cannot help remarking the uniform efforts for the cultivation of the soil which are manifested in the policy of the monastic hierarchy. wherever convents have not yet acquired wealth in the new continent, as formerly in gaul, in syria, and in the north of europe, they exercise a happy influence on the clearing of the ground and the introduction of exotic vegetation. at caripe, the conuco of the community presents the appearance of an extensive and beautiful garden. the natives are obliged to work in it every morning from six to ten, and the alcaldes and alguazils of indian race overlook their labours. these men are looked upon as great state functionaries, and they alone have the right of carrying a cane. the selection of them depends on the superior of the convent. the pedantic and silent gravity of the indian alcaldes, their cold and mysterious air, their love of appearing in form at church and in the assemblies of the people, force a smile from europeans. we were not yet accustomed to these shades of the indian character, which we found the same at the orinoco, in mexico, and in peru, among people totally different in their manners and their language. the alcaldes came daily to the convent, less to treat with the monks on the affairs of the mission, than under the pretence of inquiring after the health of the newly-arrived travellers. as we gave them brandy, their visits became more frequent than the monks desired. that which confers most celebrity on the valley of caripe, besides the extraordinary coolness of its climate, is the great cueva, or cavern of the guacharo.* (* the province of guacharucu, which delgado visited in , in the expedition of hieronimo de ortal, appears to have been situated south or south-east of macarapana. has its name any connexion with those of the cavern and the bird? or is this last of spanish origin? (laet nova orbis page ). guacharo means in castilian "one who cries and laments;" now the bird of the cavern of caripe, and the guacharaca (phasianus parraka) are very noisy birds.) in a country where the people love the marvellous, a cavern which gives birth to a river, and is inhabited by thousands of nocturnal birds, the fat of which is employed in the missions to dress food, is an everlasting object of conversation and discussion. the cavern, which the natives call "a mine of fat" is not in the valley of caripe itself, but three short leagues distant from the convent, in the direction of west-south-west. it opens into a lateral valley, which terminates at the sierra del guacharo. we set out for the sierra on the th of september, accompanied by the alcaldes, or indian magistrates, and the greater part of the monks of the convent. a narrow path led us at first towards the south, across a fine plain, covered with beautiful turf. we then turned westward, along the margin of a small river which issues from the mouth of the cavern. we ascended during three quarters of an hour, sometimes in the water, which was shallow, sometimes between the torrent and a wall of rocks, on a soil extremely slippery and miry. the falling down of the earth, the scattered trunks of trees, over which the mules could scarcely pass, and the creeping plants that covered the ground, rendered this part of the road fatiguing. we were surprised to find here, at scarcely toises above the level of the sea, a cruciferous plant, raphanus pinnatus. plants of this family are very rare in the tropics; they have in some sort a northern character, and therefore we never expected to see one on the plain of caripe at so inconsiderable an elevation. the northern character also appears in the galium caripense, the valeriana scandens, and a sanicle not unlike the s. marilandica. at the foot of the lofty mountain of the guacharo, we were only four hundred paces from the cavern, without yet perceiving the entrance. the torrent runs in a crevice hollowed out by the waters, and we went on under a cornice, the projection of which prevented us from seeing the sky. the path winds in the direction of the river; and at the last turning we came suddenly before the immense opening of the grotto. the aspect of this spot is majestic, even to the eye of a traveller accustomed to the picturesque scenery of the higher alps. i had before this seen the caverns of the peak of derbyshire, where, lying down flat in a boat, we proceeded along a subterranean river, under an arch two feet high. i had visited the beautiful grotto of treshemienshiz, in the carpathian mountains, the caverns of the hartz, and those of franconia, which are vast cemeteries,* containing bones of tigers, hyenas, and bears, as large as our horses. (* the mould, which has covered for thousands of years the soil of the caverns of gaylenreuth and muggendorf in franconia, emits even now choke-damps, or gaseous mixtures of hydrogen and nitrogen, which rise to the roof of the caves. this fact is known to the persons who show these caverns to travellers; and when i was director of the mines of the fichtelberg, i observed it frequently in the summer-time. m. laugier found in the mould of muggendorf, besides phosphate of lime, . of animal matter. i was struck, during my stay at steeben, with the ammoniacal and fetid smell produced by it, when thrown on a red-hot iron.) nature in every zone follows immutable laws in the distribution of rocks, in the form of mountains, and even in those changes which the exterior crust of our planet has undergone. so great a uniformity led me to believe that the aspect of the cavern of caripe would differ little from what i had observed in my preceding travels. the reality far exceeded my expectations. if the configuration of the grottoes, the splendour of the stalactites, and all the phenomena of inorganic nature, present striking analogies, the majesty of equinoctial vegetation gives at the same time an individual character to the aperture of the cavern. the cueva del guacharo is pierced in the vertical profile of a rock. the entrance is towards the south, and forms an arch eighty feet broad and seventy-two high. the rock which surmounts the grotto is covered with trees of gigantic height. the mammee-tree and the genipa,* (* caruto, genipa americana. the flower at caripe, has sometimes five, sometimes six stamens.) with large and shining leaves, raise their branches vertically towards the sky; whilst those of the courbaril and the erythrina form, as they extend, a thick canopy of verdure. plants of the family of pothos, with succulent stems, oxalises, and orchideae of a singular structure,* (* a dendrobium, with a gold-coloured flower, spotted with black, three inches long.) rise in the driest clefts of the rocks; while creeping plants waving in the winds are interwoven in festoons before the opening of the cavern. we distinguished in these festoons a bignonia of a violet blue, the purple dolichos, and for the first time, that magnificent solandra,* (* solandra scandens. it is the gousaticha of the chayma indians.) which has an orange-coloured flower and a fleshy tube more than four inches long. but this luxury of vegetation embellishes not only the external arch, it appears even in the vestibule of the grotto. we saw with astonishment plantain-leaved heliconias eighteen feet high, the praga palm-tree, and arborescent arums, following the course of the river, even to those subterranean places. the vegetation continues in the cave of caripe as in those deep crevices of the andes, half-excluded from the light of day, and does not disappear till, penetrating into the interior, we advance thirty or forty paces from the entrance. we measured the way by means of a cord; and we went on about four hundred and thirty feet without being obliged to light our torches. daylight penetrates far into this region, because the grotto forms but one single channel, keeping the same direction, from south-east to north-west. where the light began to fail, we heard from afar the hoarse sounds of the nocturnal birds; sounds which the natives think belong exclusively to those subterraneous places. the guacharo is of the size of our fowls. it has the mouth of the goat-suckers and procnias, and the port of those vultures whose crooked beaks are surrounded with stiff silky hairs. suppressing, with m. cuvier, the order of picae, we must refer this extraordinary bird to the passeres, the genera of which are connected with each other by almost imperceptible transitions. it forms a new genus, very different from the goatsucker, in the loudness of its voice, in the vast strength of its beak (containing a double tooth), and in its feet without the membranes which unite the anterior phalanges of the claws. it is the first example of a nocturnal bird among the passeres dentirostrati. its habits present analogies both with those of the goatsuckers and of the alpine crow.* (* corvus pyrrhocorax.) the plumage of the guacharo is of a dark bluish grey, mixed with small streaks and specks of black. large white spots of the form of a heart, and bordered with black, mark the head, wings, and tail. the eyes of the bird, which are dazzled by the light of day, are blue, and smaller than those of the goatsucker. the spread of the wings, which are composed of seventeen or eighteen quill feathers, is three feet and a half. the guacharo quits the cavern at nightfall, especially when the moon shines. it is almost the only frugiferous nocturnal bird yet known; the conformation of its feet sufficiently shows that it does not hunt like our owls. it feeds on very hard fruits, like the nutcracker* (* corvus caryocatactes, c. glandarius. our alpine crow builds its nest near the top of mount libanus, in subterranean caverns, nearly like the guacharo. it also has the horribly shrill cry of the latter.) and the pyrrhocorax. the latter nestles also in clefts of rocks, and is known by the name of the night-crow. the indians assured us that the guacharo does not pursue either the lamellicornous insects or those phalaenae which serve as food to the goatsuckers. a comparison of the beaks of the guacharo and the goatsucker serves to denote how much their habits must differ. it would be difficult to form an idea of the horrible noise occasioned by thousands of these birds in the dark part of the cavern. their shrill and piercing cries strike upon the vaults of the rocks, and are repeated by the subterranean echoes. the indians showed us the nests of the guacharos by fixing a torch to the end of a long pole. these nests were fifty or sixty feet high above our heads, in holes in the shape of funnels, with which the roof of the grotto is pierced like a sieve. the noise increased as we advanced, and the birds were scared by the light of the torches of copal. when this noise ceased a few minutes around us, we heard at a distance the plaintive cries of the birds roosting in other ramifications of the cavern. it seemed as if different groups answered each other alternately. the indians enter the cueva del guacharo once a year, near midsummer. they go armed with poles, with which they destroy the greater part of the nests. at that season several thousand birds are killed; and the old ones, as if to defend their brood, hover over the heads of the indians, uttering terrible cries. the young,* (* called los pollos del guacharo.) which fall to the ground, are opened on the spot. their peritoneum is found extremely loaded with fat, and a layer of fat reaches from the abdomen to the anus, forming a kind of cushion between the legs of the bird. this quantity of fat in frugivorous animals, not exposed to the light, and exerting very little muscular motion, reminds us of what has been observed in the fattening of geese and oxen. it is well known how greatly darkness and repose favour this process. the nocturnal birds of europe are lean, because, instead of feeding on fruits, like the guacharo, they live on the scanty produce of their prey. at the period commonly called, at caripe, the oil harvest,* (* la cosecha de la manteca.) the indians build huts with palm-leaves, near the entrance, and even in the porch of the cavern. there, with a fire of brushwood, they melt in pots of clay the fat of the young birds just killed. this fat is known by the name of butter or oil (manteca, or aceite) of the guacharo. it is half liquid, transparent, without smell, and so pure that it may be kept above a year without becoming rancid. at the convent of caripe no other oil is used in the kitchen of the monks but that of the cavern; and we never observed that it gave the aliments a disagreeable taste or smell. the race of the guacharos would have been long ago extinct, had not several circumstances contributed to its preservation. the natives, restrained by their superstitious ideas, seldom have courage to penetrate far into the grotto. it appears also, that birds of the same species dwell in neighbouring caverns, which are too narrow to be accessible to man. perhaps the great cavern is repeopled by colonies which forsake the small grottoes; for the missionaries assured us that hitherto no sensible diminution of the birds has been observed. young guacharos have been sent to the port of cumana, and have lived there several days without taking any nourishment, the seeds offered to them not suiting their taste. when the crops and gizzards of the young birds are opened in the cavern, they are found to contain all sorts of hard and dry fruits, which furnish, under the singular name of guacharo seed (semilla del guacharo), a very celebrated remedy against intermittent fevers. the old birds carry these seeds to their young. they are carefully collected, and sent to the sick at cariaco, and other places of the low regions, where fevers are generally prevalent. as we continued to advance into the cavern, we followed the banks of the small river which issues from it, and is from twenty-eight to thirty feet wide. we walked on the banks, as far as the hills formed of calcareous incrustations permitted us. where the torrent winds among very high masses of stalactites, we were often obliged to descend into its bed, which is only two feet deep. we learned with surprise, that this subterranean rivulet is the origin of the river caripe, which, at the distance of a few leagues, where it joins the small river of santa maria, is navigable for canoes. it flows into the river areo under the name of cano do terezen. we found on the banks of the subterranean rivulet a great quantity of palm-tree wood, the remains of trunks, on which the indians climb to reach the nests hanging from the roofs of the cavern. the rings, formed by the vestiges of the old footstalks of the leaves, furnish as it were the steps of a ladder perpendicularly placed. the grotto of caripe preserves the same direction, the same breadth, and its primitive height of sixty or seventy feet, to the distance of metres, or feet, accurately measured. we had great difficulty in persuading the indians to pass beyond the anterior portion of the grotto, the only part which they annually visit to collect the fat. the whole authority of 'los padres' was necessary to induce them to advance as far as the spot where the soil rises abruptly at an inclination of sixty degrees, and where the torrent forms a small subterranean cascade.* (* we find the phenomenon of a subterranean cascade, but on a much larger scale, in england, at yordas cave, near kingsdale in yorkshire.) the natives connect mystic ideas with this cave, inhabited by nocturnal birds; they believe that the souls of their ancestors sojourn in the deep recesses of the cavern. "man," say they, "should avoid places which are enlightened neither by the sun (zis), nor by the moon (nuna)." 'to go and join the guacharos,' is with them a phrase signifying to rejoin their fathers, to die. the magicians (piaches) and the poisoners (imorons) perform their nocturnal tricks at the entrance of the cavern, to conjure the chief of the evil spirits (ivorokiamo). thus in every region of the earth a resemblance may be traced in the early fictions of nations, those especially which relate to two principles governing the world, the abode of souls after death, the happiness of the virtuous and the punishment of the guilty. the most different and most barbarous languages present a certain number of images, which are the same, because they have their source in the nature of our intelligence and our sensations. darkness is everywhere connected with the idea of death. the grotto of caripe is the tartarus of the greeks; and the guacharos, which hover over the rivulet, uttering plaintive cries, remind us of the stygian birds. at the point where the river forms the subterranean cascade, a hill covered with vegetation, which is opposite to the opening of the grotto, presents a very picturesque aspect. it is seen at the extremity of a straight passage, toises in length. the stalactites descending from the roof, and resembling columns suspended in the air, are relieved on a back-ground of verdure. the opening of the cavern appeared singularly contracted, when we saw it about the middle of the day, illumined by the vivid light reflected at once from the sky, the plants, and the rocks. the distant light of day formed a strange contrast with the darkness which surrounded us in the vast cavern. we discharged our guns at a venture, wherever the cries of the nocturnal birds and the flapping of their wings, led us to suspect that a great number of nests were crowded together. after several fruitless attempts m. bonpland succeeded in killing a couple of guacharos, which, dazzled by the light of the torches, seemed to pursue us. this circumstance afforded me the means of making a drawing of this bird, which had previously been unknown to naturalists. we climbed, not without difficulty, the small hill whence the subterranean rivulet descends. we saw that the grotto was perceptibly contracted, retaining only forty feet in height, and that it continued stretching to north-east, without deviating from its primitive direction, which is parallel to that of the great valley of caripe. in this part of the cavern, the rivulet deposits a blackish mould, very like the matter which, in the grotto of muggendorf, in franconia, is called "the earth of sacrifice."* (* opfer-erde of the cavern of hohle berg (or hole mountain,--a mountain pierced entirely through.)) we could not discover whether this fine and spongy mould falls through the cracks which communicate with the surface of the ground above, or is washed down by the rain-water penetrating into the cavern. it was a mixture of silex, alumina, and vegetable detritus. we walked in thick mud to a spot where we beheld with astonishment the progress of subterranean vegetation. the seeds which the birds carry into the grotto to feed their young, spring up wherever they fix in the mould which covers the calcareous incrustations. blanched stalks, with some half-formed leaves, had risen to the height of two feet. it was impossible to ascertain the species of these plants, their form, colour, and aspect having been changed by the absence of light. these traces of organization amidst darkness forcibly excited the curiosity of the natives, who examined them with silent meditation inspired by a place they seemed to dread. they evidently regarded these subterranean plants, pale and deformed, as phantoms banished from the face of the earth. to me the scene recalled one of the happiest periods of my early youth, a long abode in the mines of freyberg, where i made experiments on the effects of blanching (etiolement), which are very different, according as the air is pure or overcharged with hydrogen or azote. the missionaries, with all their authority, could not prevail on the indians to penetrate farther into the cavern. as the roof became lower the cries of the guacharos were more and more shrill. we were obliged to yield to the pusillanimity of our guides, and trace back our steps. the appearance of the cavern was however very uniform. we found that a bishop of st. thomas of guiana had gone farther than ourselves. he had measured nearly feet from the mouth to the spot where he stopped, but the cavern extended still farther. the remembrance of this fact was preserved in the convent of caripe, without the exact period being noted. the bishop had provided himself with great torches of white castile wax. we had torches composed only of the bark of trees and native resin. the thick smoke which issued from these torches, in a narrow subterranean passage, hurts the eyes and obstructs the respiration. on turning back to go out of the cavern, we followed the course of the torrent. before our eyes became dazzled with the light of day we saw on the outside of the grotto the water of the river sparkling amid the foliage of the trees which shaded it. it was like a picture placed in the distance, the mouth of the cavern serving as a frame. having at length reached the entrance, we seated ourselves on the bank of the rivulet, to rest after our fatigues. we were glad to be beyond the hoarse cries of the birds, and to leave a place where darkness does not offer even the charm of silence and tranquillity. we could scarcely persuade ourselves that the name of the grotto of caripe had hitherto been unknown in europe;* for the guacharos alone might have sufficed to render it celebrated. (* it is surprising that father gili, author of the saggio di storia americana, does not mention it, though he had in his possession a manuscript written in at the convent of caripe. i gave the first information respecting the cueva del guacharo in , in my letters to messrs. delambre and delametherie, published in the journal de physique.) these nocturnal birds have been no where yet discovered, except in the mountains of caripe and cumanacoa. the missionaries had prepared a repast at the entry of the cavern. leaves of the banana and the vijao,* (* heliconia bihai, linn. the creoles have changed the b of the haitian word bihao into v, and the h into j, agreeably to the castilian pronunciation.) which have a silky lustre, served us as a table-cloth, according to the custom of the country. nothing was wanting to our enjoyment, not even remembrances, which are so rare in those countries, where generations disappear without leaving a trace of their existence. before we quit the subterranean rivulet and the nocturnal birds, let us cast a last glance at the cavern of the guacharo, and the whole of the physical phenomena it presents. when we have step by step pursued a long series of observations modified by the localities of a place, we love to stop and raise our views to general considerations. do the great cavities, which are exclusively called caverns, owe their origin to the same causes as those which have produced the lodes of veins and of metalliferous strata, or the extraordinary phenomenon of the porosity of rocks? do grottoes belong to every formation, or to that period only when organized beings began to people the surface of the globe? these geological questions can be solved only so far as they are directed by the actual state of things, that is, of facts susceptible of being verified by observation. considering rocks according to the succession of eras, we find that primitive formations exhibit very few caverns. the great cavities which are observed in the oldest granite, and which are called fours (ovens) in switzerland and in the south of france, when they are lined with rock crystals, arise most frequently from the union of several contemporaneous veins of quartz,* (* gleichzeitige trummer. to these stone veins which appear to be of the same age as the rock, belong the veins of talc and asbestos in serpentine, and those of quartz traversing schist (thonschiefer). jameson on contemporaneous veins, in the mem. of the wernerian soc.) of feldspar, or of fine-grained granite. the gneiss presents, though more seldom, the same phenomenon; and near wunsiedel,* (* in franconia, south-east of luchsburg.) at the fichtelgebirge, i had an opportunity of examining crystal fours of two or three feet diameter, in a part of the rock not traversed by veins. we are ignorant of the extent of the cavities which subterranean fires and volcanic agitations may have produced in the bowels of the earth in those primitive rocks, which, containing considerable quantities of amphibole, mica, garnet, magnetic iron-stone, and red schorl (titanite), appear to be anterior to granite. we find some fragments of these rocks among the matters ejected by volcanoes. the cavities can be considered only as partial and local phenomena; and their existence is scarcely any contradiction to the notions we have acquired from the experiments of maskelyne and cavendish on the mean density of the earth. in the primitive mountains open to our researches, real grottoes, those which have some extent, belong only to calcareous formations, such as the carbonate or sulphate of lime. the solubility of these substances appears to have favoured the action of the subterranean waters for ages. the primitive limestone presents spacious caverns as well as transition limestone,* and that which is exclusively called secondary. (* in the primitive limestone are found the kuetzel-loch, near kaufungen in silesia, and probably several caverns in the islands of the archipelago. in the transition limestone we remark the caverns of elbingerode, of rubeland, and of scharzfeld, in the hartz; those of the salzfluhe in the grisons; and, according to mr. greenough, that of torbay in devonshire.) if these caverns be less frequent in the first, it is because this stone forms in general only layers subordinate to the mica-slate,* (* sometimes to gneiss, as at the simplon, between dovredo and crevola.) and not a particular system of mountains, into which the waters may filter, and circulate to great distances. the erosions occasioned by this element depend not only on its quantity, but also on the length of time during which it remains, the velocity it acquires by its fall, and the degree of solubility of the rock. i have observed in general, that the waters act more easily on the carbonates and the sulphates of lime of secondary mountains than on the transition limestones, which have a considerable mixture of silex and carbon. on examining the internal structure of the stalactites which line the walls of caverns, we find in them all the characters of a chemical precipitate. as we approach those periods in which organic life develops itself in a greater number of forms, the phenomenon of grottoes becomes more frequent. there exist several under the name of baumen,* (* in the dialect of the german swiss, balmen. the baumen of the sentis, of the mole, and of the beatenberg, on the borders of the lake of thun, belong to the alpine limestone.) not in the ancient sandstone to which the great coal formation belongs, but in the alpine limestone, and in the jura limestone, which is often only the superior part of the alpine formation. the jura limestone* (* i may mention only the grottoes of boudry, motiers-travers, and valorbe, in the jura; the grotto of balme near geneva; the caverns between muggendorf and gaylenreuth in franconia; sowia jama, ogrodzimiec, and wlodowice, in poland.) so abounds with caverns in both continents, that several geologists of the school of freyberg have given it the name of cavern-limestone (hohlenkalkstein). it is this rock which so often interrupts the course of rivers, by engulfing them into its bosom. in this also is formed the famous cueva del guacharo, and the other grottoes of the valley of caripe. the muriatiferous gypsum,* (* gypsum of bottendorf, schlottengyps.) whether it be found in layers in the jura or alpine limestone, or whether it separate these two formations, or lie between the alpine limestone and argillaceous sandstone, also presents, on account of its great solubility, enormous cavities, sometimes communicating with each other at several leagues distance. after the limestone and gypseous formations, there would remain to be examined, among the secondary rocks, a third formation, that of the argillaceous sandstone, newer than the brine-spring formations; but this rock, composed of small grains of quartz cemented by clay, seldom contains caverns; and when it does, they are not extensive. progressively narrowing towards their extremity, their walls are covered with a brown ochre. we have just seen, that the form of grottoes depends partly on the nature of the rocks in which they are found; but this form, modified by exterior agents, often varies even in the same formation. the configuration of caverns, like the outline of mountains, the sinuosity of valleys, and so many other phenomena, present at first sight only irregularity and confusion. the appearance of order is resumed, when we can extend our observations over a vast space of ground, which has undergone violent, but periodical and uniform revolutions. from what i have seen in the mountains of europe, and in the cordilleras of america, caverns may be divided, according to their interior structure, into three classes. some have the form of large clefts or crevices, like veins not filled with ore; such as the cavern of rosenmuller, in franconia, elden-hole, in the peak of derbyshire, and the sumideros of chamacasapa in mexico. other caverns are open to the light at both ends. these are rocks really pierced; natural galleries, which run through a solitary mountain: such are the hohleberg of muggendorf, and the famous cavern called dantoe by the ottomite indians, and the bridge of the mother of god, by the mexican spaniards. it is difficult to decide respecting the origin of these channels, which sometimes serve as beds for subterranean rivers. are these pierced rocks hollowed out by the impulse of a current? or should we rather admit that one of the openings of the cavern is owing to a falling down of the earth subsequent to its original formation; to a change in the external form of the mountain, for instance, to a new valley opened on its flank? a third form of caverns, and the most common of the whole, exhibits a succession of cavities, placed nearly on the same level, running in the same direction, and communicating with each other by passages of greater or less breadth. to these differences of general form are added other circumstances not less remarkable. it often happens, that grottoes of little space have extremely wide openings; whilst we have to creep under very low vaults, in order to penetrate into the deepest and most spacious caverns. the passages which unite partial grottoes, are generally horizontal. i have seen some, however, which resemble funnels or wells, and which may be attributed to the escape of some elastic fluid through a mass before being hardened. when rivers issue from grottoes, they form only a single, horizontal, continuous channel, the dilatations of which are almost imperceptible; as in the cueva del guacharo we have just described, and the cavern of san felipe, near tehuilotepec in the western cordilleras of mexico. the sudden disappearance* of the river (* in the night of the th april, .), which took its rise from this last cavern, has impoverished a district in which farmers and miners equally require water for refreshing the soil and for working hydraulic machinery. considering the variety of structure exhibited by grottoes in both hemispheres, we cannot but refer their formation to causes totally different. when we speak of the origin of caverns we must choose between two systems of natural philosophy: one of these systems attributes every thing to instantaneous and violent commotions (for example, to the elastic force of vapours, and to the heavings occasioned by volcanoes); while the other rests on the operation of small powers, which produce effects almost insensibly by progressive action. those who love to indulge in geological hypotheses must not, however, forget the horizontality so often remarked amidst gypseous and calcareous mountains, in the position of grottoes communicating with each other by passages. this almost perfect horizontality, this gentle and uniform slope, appears to be the result of a long abode of the waters, which enlarge by erosion clefts already existing, and carry off the softer parts the more easily, as clay or muriate of soda is found mixed with the gypsum and fetid limestone. these effects are the same, whether the caverns form one long and continued range, or several of these ranges lie one over another, as happens almost exclusively in gypseous mountains. that which in shelly or neptunean rocks is caused by the action of the waters, appears sometimes to be in the volcanic rocks the effect of gaseous emanations* acting in the direction where they find the least resistance. (* at vesuvius, the duke de la torre showed me, in , in currents of recent lava, cavities extending in the direction of the current, six or seven feet long and three feet high. these little volcanic caverns were lined with specular iron, which cannot be called oligiste iron, since m. gay-lussac's last experiments on the oxides of iron.) when melted matter moves on a very gentle slope, the great axis of the cavity formed by the elastic fluids is nearly horizontal, or parallel to the plane on which the movement of transition takes place. a similar disengagement of vapours, joined to the elastic force of the gases, which penetrate strata softened and raised up, appears sometimes to have given great extent to the caverns found in trachytes or trappean porphyries. these porphyritic caverns, in the cordilleras of quito and peru, bear the indian name of machays.* (* machay is a word of the quichua language, commonly called by the spaniards the incas' language. callancamachay means a cavern as large as a house, a cavern that serves as a tambo or caravansarai.) they are in general of little depth. they are lined with sulphur, and differ by the enormous size of their openings from those observed in volcanic tufas* in italy, at teneriffe, and in the andes. (*sometimes fire acts like water in carrying off masses, and thus the cavities may be caused by an igneous, though more frequently by an aqueous erosion or solution.) it is by connecting in the mind the primitive, secondary, and volcanic rocks, and distinguishing between the oxidated crust of the globe, and the interior nucleus, composed perhaps of metallic and inflammable substances, that we may account for the existence of grottoes everywhere. they act in the economy of nature as vast reservoirs of water and of elastic fluids. the gypseous caverns glitter with crystallized selenites. vitreous crystallized plates of brown and yellow stand out on a striated ground composed of layers of alabaster and fetid limestone. the calcareous grottoes have a more uniform tint. they are more beautiful, and richer in stalactites, in proportion as they are narrower, and the circulation of air is less free. by being spacious, and accessible to air, the cavern of caripe is almost destitute of those incrustations, the imitative forms of which are in other countries objects of popular curiosity. i also sought in vain for subterranean plants, those cryptogamia of the family of the usneaceae, which we sometimes find fixed on the stalactites, like ivy on walls, when we penetrate for the first time into a lateral grotto.* (* lichen tophicola was discovered when the beautiful cavern of rosenmuller in franconia was first opened. the cavity containing the lichen was found closed on all sides by enormous masses of stalactite.) the caverns in mountains of gypsum often contain mephitic emanations and deleterious gases. it is not the sulphate of lime that acts on the atmospheric air, but the clay slightly mixed with carbon, and the fetid limestone, so often mingled with the gypsum. we cannot yet decide, whether the swinestone acts as a hydrosulphuret, or by means of a bituminous principle.* (* that description of fetid limestone called by the german mineralogists stinkstein is always of a blackish brown colour. it is only by decomposition that it becomes white, after having acted on the surrounding air. the stinkstein which is of secondary formation, must not be confounded with a very white primitive granular limestone of the island of thasos, which emits, when scraped, a smell of sulphuretted hydrogen. this marble is coarser grained than carrara (marmor lunense). it was frequently employed by the grecian sculptors, and i often picked up fragments of it at the villa adriani, near rome.) its property of absorbing oxygen gas is known to all the miners of thuringia. it is the same as the action of the carburetted clay of the gypseous grottoes, and of the great chambers (sinkwerke) dug in mines of fossil salt which are worked by the introduction of fresh water. the caverns of calcareous mountains are not exposed to those decompositions of the atmospheric air, unless they contain bones of quadrupeds, or the mould mixed with animal gluten and phosphate of lime, from which arise inflammable and fetid gases. though we made many enquiries among the inhabitants of caripe, cumanacoa, and cariaco, we did not learn that they had ever discovered in the cavern of guacharo either the remains of carnivorous animals, or those bony breccias of herbivorous animals, which are found in the caverns of germany and hungary, and in the clefts of the calcareous rocks of gibraltar. the fossil bones of the megatherium, of the elephant, and of the mastodon, which travellers have brought from south america, have all been found in the light soil of the valleys and table-lands. excepting the megalonyx,* a kind of sloth of the size of an ox, described by mr. jefferson, i know not a single instance of the skeleton of an animal buried in a cavern of the new world. (* the megalonyx was found in the caverns of green briar, in virginia, at the distance of leagues from the megatherium, which resembles it very much, and is of the size of the rhinoceros.) the extreme scarcity of this geological phenomenon will appear the less surprising to us, if we recollect, that in france, england, and italy, there are also a great number of grottoes in which we have never met with any vestige of fossil bones. although, in primitive nature, whatever relates to ideas of extent and mass is of no great importance, yet i may observe, that the cavern of caripe is one of the most spacious known to exist in limestone formations. it is at least metres or feet in length.* (* the famous baumannshohle in the hartz, according to messrs. gilbert and ilsen, is only feet in length; the cavern of scharzfeld ; that of gaylenreuth ; that of antiparos . but according to saussure, the grotto of balme is feet.) owing to the different degrees of solubility in rocks, it is generally not in calcareous mountains, but in gypseous formations, that we find the most extensive succession of grottoes. in saxony there are some in gypsum several leagues in length; for instance, that of wimelburg, which communicates with the cavern of cresfield. the determination of the temperature of grottoes presents a field for interesting observation. the cavern of caripe, situated nearly in the latitude of degrees minutes, consequently in the centre of the torrid zone, is elevated toises above the level of the sea in the gulf of cariaco. we found that, in every part of it, in the month of september, the temperature of the internal air was between . and . degrees of the centesimal thermometer; the external atmosphere being at . degrees. at the entrance of the cavern, the thermometer in the open air was at . degrees; but when immersed in the water of the little subterranean river, it marked, even to the end of the cavern, . degrees. these experiments are very interesting, if we reflect on the tendency to equilibrium of heat, in the waters, the air, and the earth. when i left europe, men of science were regretting that they had not sufficient data on what is called the temperature of the interior of the globe; and it is but very recently that efforts have been made, and with some success, to solve the grand problem of subterranean meteorology. the stony strata that form the crust of our planet, are alone accessible to our examination; and we now know that the mean temperature of these strata varies not only with latitudes and heights, but that, according to the position of the several places, it performs also, in the space of a year, regular oscillations round the mean heat of the neighbouring atmosphere. the time is gone by when men were surprised to find, in other zones, the heat of grottoes and wells differing from that observed in the caves of the observatory at paris. the same instrument which in those caves marks degrees, rises in the subterraneous caverns of the island of madeira, near funchal, to . degrees; in joseph's well, at cairo* to . degrees (* at funchal (latitude degrees minutes) the mean temperature of the air is . degrees, and at cairo (latitude degrees minutes), according to nouet, it is . degrees.); in the grottoes of the island of cuba to or degrees.* (* the mean temperature of the air at the havannah, according to mr. ferrer, is . degrees.) this increase is nearly in proportion to that of the mean temperature of the atmosphere, from latitude degrees to the tropics. we have just seen that, in the cueva del guacharo, the water of the river is nearly degrees colder than the ambient air of the cavern. the water, whether in filtering through the rocks, or in running over stony beds, doubtless imbibes the temperature of these beds. the air contained in the grotto, on the contrary, is not in repose; it communicates with the external atmosphere. though under the torrid zone, the changes of the external temperature are exceedingly trifling, currents are formed, which modify periodically the internal air. it is consequently the temperature of the waters, that of . degrees, which we might look upon as the temperature of the earth in those mountains, if we were sure that the waters do not descend rapidly from more elevated neighbouring mountains. it follows from these observations, that when we cannot obtain results perfectly exact, we find at least under each zone certain numbers which indicate the maximum and minimum. at caripe, in the equinoctial zone, at an elevation of toises, the mean temperature of the globe is not below . degrees, which was the degree indicated by the water of the subterranean river. we can even prove that this temperature of the globe is not above degrees, since the air of the cavern, in the month of september, was found to be at . degrees. as the mean temperature of the atmosphere, in the hottest month, does not exceed . degrees,* it is probable that a thermometer in the grotto would not rise higher than degrees at any season of the year. (* the mean temperature of the month of september at caripe is . degrees; and on the coast of cumana, where we had opportunities of making numerous observations, the mean heat of the warmest months differs only . degrees from that of the coldest.) chapter . . departure from caripe. mountain and forest of santa maria. mission of catuaro. port of cariaco. the days we passed at the capuchin convent in the mountains of caripe, glided swiftly away, though our manner of living was simple and uniform. from sunrise to nightfall we traversed the forests and neighbouring mountains, to collect plants. when the winter rains prevented us from undertaking distant excursions, we visited the huts of the indians, the conuco of the community, or those assemblies in which the alcaldes every evening arrange the labours of the succeeding day. we returned to the monastery only when the sound of the bell called us to the refectory to share the repasts of the missionaries. sometimes, very early in the morning, we followed them to the church, to attend the doctrina, that is to say, the religious instruction of the indians. it was rather a difficult task to explain dogmas to the neophytes, especially those who had but a very imperfect knowledge of the spanish language. on the other hand, the monks are as yet almost totally ignorant of the language of the chaymas; and the resemblance of sounds confuses the poor indians and suggests to them the most whimsical ideas. of this i may cite an example. i saw a missionary labouring earnestly to prove that infierno, hell, and invierno, winter, were not one and the same thing; but as different as heat and cold. the chaymas are acquainted with no other winter than the season of rains; and consequently they imagined the hell of the whites to be a place where the wicked are exposed to frequent showers. the missionary harangued to no purpose: it was impossible to efface the first impression produced by the analogy between the two consonants. he could not separate in the minds of the neophytes the ideas of rain and hell; invierno and infierno. after passing almost the whole day in the open air, we employed our evenings, at the convent, in making notes, drying our plants, and sketching those that appeared to form new genera. unfortunately the misty atmosphere of a valley, where the surrounding forests fill the air with an enormous quantity of vapour, was unfavourable to astronomical observations. i spent a part of the nights waiting to take advantage of the moment when some star should be visible between the clouds, near its passage over the meridian. i often shivered with cold, though the thermometer only sunk to degrees, which is the temperature of the day in our climates towards the end of september. the instruments remained set up in the court of the convent for several hours, yet i was almost always disappointed in my expectations. some good observations of fomalhaut and of deneb have given degrees minutes seconds as the latitude of caripe; which proves that the position indicated in the maps of caulin is minutes wrong, and in that of arrowsmith minutes. observations of corresponding altitudes of the sun having given me the true time, within about seconds, i was enabled to determine the magnetic variation with precision, at noon. it was, on the th of september, , degrees minutes seconds north-east; consequently degrees minutes seconds less than at cumana. if we attend to the influence of the horary variations, which in these countries do not in general exceed minutes, we shall find, that at considerable distances the variation changes less rapidly than is usually supposed. the dip of the needle was . degrees, centesimal division, and the number of oscillations, expressing the intensity of the magnetic forces, rose to in ten minutes. the vexation of seeing the stars disappear in a misty sky was the only disappointment we felt in the valley of caripe. the aspect of this spot presents a character at once wild and tranquil, gloomy and attractive. in the solitude of these mountains we are perhaps less struck by the new impressions we receive at every step, than with the marks of resemblance we trace in climates the most remote from each other. the hills by which the convent is backed, are crowned with palm-trees and arborescent ferns. in the evenings, when the sky denotes rain, the air resounds with the monotonous howling of the alouate apes, which resembles the distant sound of wind when it shakes the forest. yet amid these strange sounds, these wild forms of plants, and these prodigies of a new world, nature everywhere speaks to man in a voice familiar to him. the turf that overspreads the soil: the old moss and fern that cover the roots of the trees; the torrents that gush down the sloping banks of the calcareous rocks; in fine, the harmonious accordance of tints reflected by the waters, the verdure, and the sky; everything recalls to the traveller, sensations which he has already felt. the beauties of this mountain scenery so much engaged us, that we were very tardy in observing the embarrassment felt by our kind entertainers the monks. they had but a slender provision of wine and wheaten bread; and although in those high regions both are considered as belonging merely to the luxuries of the table, yet we saw with regret, that our hosts abstained from them on our account. our portion of bread had already been diminished three-fourths, yet violent rains still obliged us to delay our departure for two days. how long did this delay appear! it made us dread the sound of the bell that summoned us to the refectory. we departed at length on the nd of september, followed by four mules, laden with our instruments and plants. we had to descend the north-east slope of the calcareous alps of new andalusia, which we have called the great chain of the brigantine and the cocollar. the mean elevation of this chain scarcely exceeds six or seven hundred toises: in respect to height and geological constitution, we may compare it to the chain of the jura. notwithstanding the inconsiderable elevation of the mountains of cumana, the descent is extremely difficult and dangerous in the direction of cariaco. the cerro of santa maria, which the missionaries ascend in their journey from cumana to their convent at caripe, is famous for the difficulties it presents to travellers. on comparing these mountains with the andes of peru, the pyrenees, and the alps, which we successively visited, it has more than once occurred to us, that the less lofty summits are sometimes the most inaccessible. on leaving the valley of caripe, we first crossed a ridge of hills north-east of the convent. the road led us along a continual ascent through a vast savannah, as far as the table-land of guardia de san augustin. we there halted to wait for the indian who carried the barometer. we found ourselves to be at toises of absolute elevation, or a little higher than the bottom of the cavern of guacharo. the savannahs or natural meadows, which yield excellent pasture for the cows of the convent, are totally devoid of trees or shrubs. it is the domain of the monocotyledonous plants; for amidst the gramina only a few maguey* plants rise here and there (* agave americana.); their flowery stalks being more than twenty-six feet high. having reached the table-land of guardia, we appeared to be transported to the bed of an old lake, levelled by the long-continued abode of the waters. we seemed to trace the sinuosities of the ancient shore in the tongues of land which jut out from the craggy rock, and even in the distribution of the vegetation. the bottom of the basin is a savannah, while its banks are covered with trees of full growth. this is probably the most elevated valley in the provinces of venezuela and cumana. one cannot but regret, that a spot favoured by so temperate a climate, and which without doubt would be fit for the culture of corn, is totally uninhabited. from the table-land of guardia we continued to descend, till we reached the indian village of santa cruz. we passed at first along a slope extremely slippery and steep, to which the missionaries had given the name of baxada del purgatorio, or descent of purgatory. it is a rock of schistose sandstone, decomposed, covered with clay, the talus of which appears frightfully steep, from the effect of a very common optical illusion. when we look down from the top to the bottom of the hill the road seems inclined more than degrees. the mules in going down draw their hind legs near to their fore legs, and lowering their cruppers, let themselves slide at a venture. the rider runs no risk, provided he slacken the bridle, thereby leaving the animal quite free in his movements. from this point we perceived towards the left the great pyramid of guacharo. the appearance of this calcareous peak is very picturesque, but we soon lost sight of it, on entering the thick forest, known by the name of the montana de santa maria. we descended without intermission for seven hours. it is difficult to conceive a more tremendous descent; it is absolutely a road of steps, a kind of ravine, in which, during the rainy season, impetuous torrents dash from rock to rock. the steps are from two to three feet high, and the beasts of burden, after measuring with their eyes the space necessary to let their load pass between the trunks of the trees, leap from one rock to another. afraid of missing their mark, we saw them stop a few minutes to scan the ground, and bring together their four feet like wild goats. if the animal does not reach the nearest block of stone, he sinks half his depth into the soft ochreous clay, that fills up the interstices of the rock. when the blocks are wanting, enormous roots serve as supports for the feet of men and beasts. some of these roots are twenty inches thick, and they often branch out from the trunks of the trees much above the level of the soil. the creoles have sufficient confidence in the address and instinct of the mules, to remain in their saddles during this long and dangerous descent. fearing fatigue less than they did, and being accustomed to travel slowly for the purpose of gathering plants and examining the nature of the rocks, we preferred going down on foot; and, indeed, the care which our chronometers demanded, left us no liberty of choice. the forest that covers the steep flank of the mountain of santa maria, is one of the thickest i ever saw. the trees are of stupendous height and size. under their bushy, deep green foliage, there reigns continually a kind of dim daylight, a peculiar sort of obscurity, of which our forests of pines, oaks, and beech-trees, convey no idea. notwithstanding its elevated temperature, it is difficult to believe that the air can dissolve the quantity of water exhaled from the surface of the soil, the foliage of the trees, and their trunks: the latter are covered with a drapery of orchideae, peperomia, and other succulent plants. with the aromatic odour of the flowers, the fruit, and even the wood, is mingled that which we perceive in autumn in misty weather. here, as in the forests of the orinoco, fixing our eyes on the top of the trees, we discerned streams of vapour, whenever a solar ray penetrated, and traversed the dense atmosphere. our guides pointed out to us among those majestic trees, the height of which exceeded or feet, the curucay of terecen. it yields a whitish liquid, and very odoriferous resin, which was formerly employed by the cumanagoto and tagiri indians, to perfume their idols. the young branches have an agreeable taste, though somewhat astringent. next to the curucay and enormous trunks of hymenaea, (the diameter of which was more than nine or ten feet), the trees which most excited our attention were the dragon's blood (croton sanguifluum), the purple-brown juice of which flows down a whitish bark; the calahuala fern, different from that of peru, but almost equally medicinal;* (* the calahuala of caripe is the polypodium crassifolium; that of peru, the use of which has been so much extended by messrs. ruiz and pavon, comes from the aspidium coriaceum, willd. (tectaria calahuala, cav.) in commerce the diaphoretic roots of the polypodium crassifolium, and of the acrostichum huascaro, are mixed with those of the calahuala or aspidium coriaceum.) and the palm-trees, irasse, macanilla, corozo, and praga.* (* aiphanes praga.) the last yields a very savoury palm-cabbage, which we had sometimes eaten at the convent of caripe. these palms with pinnated and thorny leaves formed a pleasing contrast to the fern-trees. one of the latter, the cyathea speciosa,* grows to the height of more than thirty-five feet, a prodigious size for plants of this family. (* possibly a hemitelia of robert brown. the trunk alone is from to feet long. this and the cyathea excelsa of the mauritius, are the most majestic of all the fern-trees described by botanists. the total number of these gigantic cryptogamous plants amounts at present to species, that of the palm-trees to . with the cyathea grow, on the mountain of santa maria, rhexia juniperina, chiococca racemosa, and commelina spicata.) we discovered here, and in the valley of caripe, five new kinds of arborescent ferns.* (* meniscium arborescens, aspidium caducum, a. rostratum, cyathea villosa, and c. speciosa.) in the time of linnaeus, botanists knew no more than four on both continents. we observed that the fern-trees are in general much more rare than the palm-trees. nature has confined them to temperate, moist, and shady places. they shun the direct rays of the sun, and while the pumos, the corypha of the steppes and other palms of america, flourish on the barren and burning plains, these ferns with arborescent trunks, which at a distance look like palm-trees, preserve the character and habits of cryptogamous plants. they love solitary places, little light, moist, temperate and stagnant air. if they sometimes descend towards the sea-coast, it is only under cover of a thick shade. the old trunks of the cyathea and the meniscium are covered with a carbonaceous powder, which, probably being deprived of hydrogen, has a metallic lustre like plumbago. no other plant presents this phenomenon; for the trunks of the dicotyledons, in spite of the heat of the climate, and the intensity of the light, are less burnt within the tropics than in the temperate zone. it may be said that the trunks of the ferns, which, like the monocotyledons, are enlarged by the remains of the petioles, decay from the circumference to the centre; and that, deprived of the cortical organs through which the elaborated juices descend to the roots, they are burnt more easily by the action of the oxygen of the atmosphere. i brought to europe some powders with metallic lustre, taken from very old trunks of meniscium and aspidium. in proportion as we descended the mountain of santa maria, we saw the arborescent ferns diminish, and the number of palm-trees increase. the beautiful large-winged butterflies (nymphales), which fly at a prodigious height, became more common. everything denoted our approach to the coast, and to a zone in which the mean temperature of the day is from to degrees. the weather was cloudy, and led us to fear one of those heavy rains, during which from to . inches of water sometimes falls in a day. the sun at times illumined the tops of the trees; and, though sheltered from its rays, we felt an oppressive heat. thunder rolled at a distance; the clouds seemed suspended on the top of the lofty mountains of the guacharo; and the plaintive howling of the araguatoes, which we had so often heard at caripe, denoted the proximity of the storm. we now for the first time had a near view of these howling apes. they are of the family of the alouates,* (* stentor, geoffroy.) the different species of which have long been confounded one with another. the small sapajous of america, which imitate in whistling the tones of the passeres, have the bone of the tongue thin and simple, but the apes of large size, as the alouates and marimondes,* (* ateles, geoffroy.) have the tongue placed on a large bony drum. their superior larynx has six pouches, in which the voice loses itself; and two of which, shaped like pigeons' nests, resemble the inferior larynx of birds. the air driven with force into the bony drum produces that mournful sound which characterises the araguatoes. i sketched on the spot these organs, which are imperfectly known to anatomists, and published the description of them on my return to europe. the araguato, which the tamanac indians call aravata,* (* in the writings of the early spanish missionaries, this monkey is described by the names of aranata and araguato. in both names we easily discover the same root. the v has been transformed into g and n. the name of arabata, which gumilla gives to the howling apes of the lower orinoco, and which geoffroy thinks belongs to the s. straminea of great paria, is the same tamanac word aravata. this identity of names need not surprise us. the language of the chayma indians of cumana is one of the numerous branches of the tamanac language, and the latter is connected with the caribbee language of the lower orinoco.) and the maypures marave, resembles a young bear.* (* alouate ourse (simia ursina).) it is three feet long, reckoning from the top of the head (which is small and very pyramidal) to the beginning of the prehensile tail. its fur is bushy, and of a reddish brown; the breast and belly are covered with fine hair, and not bare as in the mono colorado, or alouate roux of buffon, which we carefully examined in going from carthagena to santa fe de bogota. the face of the araguato is of a blackish blue, and is covered with a fine and wrinkled skin: its beard is pretty long; and, notwithstanding the direction of the facial line, the angle of which is only thirty degrees, the araguato has, in the expression of the countenance, as much resemblance to man as the marimonde (s. belzebuth, bresson) and the capuchin of the orinoco (s. chiropotes). among thousands of araguatoes which we observed in the provinces of cumana, caracas, and guiana, we never saw any change in the reddish brown fur of the back and shoulders, whether we examined individuals or whole troops. it appeared to me in general, that variety of colour is less frequent among monkeys than naturalists suppose. the araguato of caripe is a new species of the genus stentor, which i have above described. it differs equally from the ouarine (s. guariba) and the alouate roux (s. seniculus, old man of the woods). its eye, voice, and gait, denote melancholy. i have seen young araguatoes brought up in indian huts. they never play like the little sagoins, and their gravity was described with much simplicity by lopez de gomara, in the beginning of the sixteenth century. "the aranata de los cumaneses," says this author, "has the face of a man, the beard of a goat, and a grave demeanour (honrado gesto.)" monkeys are more melancholy in proportion as they have more resemblance to man. their sprightliness diminishes, as their intellectual faculties appear to increase. we stopped to observe some howling monkeys, which, to the number of thirty or forty, crossed the road, passing in a file from one tree to another over the horizontal and intersecting branches. while we were observing their movements, we saw a troop of indians going towards the mountains of caripe. they were without clothing, as the natives of this country generally are. the women, laden with rather heavy burdens, closed the march. the men were all armed; and even the youngest boys had bows and arrows. they moved on in silence, with their eyes fixed on the ground. we endeavoured to learn from them whether we were yet far from the mission of santa cruz, where we intended passing the night. we were overcome with fatigue, and suffered from thirst. the heat increased as the storm drew near, and we had not met with a single spring on the way. the words si, patre; no, patre; which the indians continually repeated, led us to think they understood a little spanish. in the eyes of a native every white man is a monk, a padre; for in the missions the colour of the skin characterizes the monk, more than the colour of the garment. in vain we questioned them respecting the length of the way: they answered, as if by chance, si and no, without our being able to attach any precise sense to their replies. this made us the more impatient, as their smiles and gestures indicated their wish to direct us; and the forest seemed at every step to become thicker and thicker. at length we separated from the indians; our guides were able to follow us only at a distance, because the beasts of burden fell at every step in the ravines. after journeying for several hours, continually descending on blocks of scattered rock, we found ourselves unexpectedly at the outlet of the forest of santa maria. a savannah, the verdure of which had been renewed by the winter rains, stretched before us farther than the eye could reach. on the left we discovered a narrow valley, extending as far as the mountains of the guacharo, and covered with a thick forest. looking downward, the eye rested on the tops of the trees, which, at eight hundred feet below the road, formed a carpet of verdure of a dark and uniform tint. the openings in the forest appeared like vast funnels, in which we could distinguish by their elegant forms and pinnated leaves, the praga and irasse palms. but what renders this spot eminently picturesque, is the aspect of the sierra del guacharo. its northern slope, in the direction of the gulf of cariaco, is abrupt. it presents a wall of rock, an almost vertical profile, exceeding feet in height. the vegetation which covers this wall is so scanty, that the eye can follow the lines of the calcareous strata. the summit of the sierra is flat, and it is only at its eastern extremity, that the majestic peak of the guacharo rises like an inclined pyramid, its form resembles that of the needles and horns* of the alps. (* the shreckhorner, the finsteraarhorn, etc.) the savannah we crossed to the indian village of santa cruz is composed of several smooth plateaux, lying above each other like terraces. this geological phenomenon, which is repeated in every climate, seems to indicate a long abode of the waters in basins that have poured them from one to the other. the calcareous rock is no longer visible, but is covered with a thick layer of mould. the last time we saw it in the forest of santa maria it was slightly porous, and looked more like the limestone of cumanacoa than that of caripe. we there found brown iron-ore disseminated in patches, and if we were not deceived in our observation, a cornu-ammonis, which we could not succeed in our attempt to detach. it was seven inches in diameter. this fact is the more important, as in this part of america we have never seen ammonites. the mission of santa cruz is situated in the midst of the plain. we reached it towards the evening, suffering much from thirst, having travelled nearly eight hours without finding water. the thermometer kept at degrees; accordingly we were not more than toises above the level of the sea. we passed the night in one of those ajupas called king's houses, which, as i have already said, serve as tambos or caravanserais to travellers. the rains prevented any observations of the stars; and the next day, the rd of september, we continued our descent towards the gulf of cariaco. beyond santa cruz a thick forest again appears; and in it we found, under tufts of melastomas, a beautiful fern, with osmundia leaves, which forms a new genus of the order of polypodiaceous plants.* (* polybotya.) having reached the mission of catuaro, we were desirous of continuing our journey eastward by santa rosalia, casanay, san josef, carupano, rio carives, and the montana of paria; but we learnt with great regret, that torrents of rain had rendered the roads impassable, and that we should run the risk of losing the plants we had already gathered. a rich planter of cacao-trees was to accompany us from santa rosalia to the port of carupano; but when the time of departure approached, we were informed that his affairs had called him to cumana. we resolved in consequence to embark at cariaco, and to return directly by the gulf, instead of passing between the island of margareta and the isthmus of araya. the mission of catuaro is situated on a very wild spot. trees of full growth still surround the church, and the tigers come by night to devour the poultry and swine belonging to the indians. we lodged at the dwelling of the priest, a monk of the congregation of the observance, to whom the capuchins had confided the mission, because priests of their own community were wanting. at this mission we met don alexandro mexia, the corregidor of the district, an amiable and well-educated man. he gave us three indians, who, armed with their machetes, were to precede us, and cut our way through the forest. in this country, so little frequented, the power of vegetation is such at the period of the great rains, that a man on horseback can with difficulty make his way through narrow paths, covered with lianas and intertwining branches. to our great annoyance, the missionary of catuaro insisted on conducting us to cariaco; and we could not decline the proposal. the movement for independence, which had nearly broken out at caracas in , had been preceded and followed by great agitation among the slaves at coro, maracaybo, and cariaco. at the last of these places an unfortunate negro had been condemned to die, and our host, the vicar of catuaro, was going thither to offer him spiritual comfort. during our journey we could not escape conversations, in which the missionary pertinaciously insisted on the necessity of the slave-trade, on the innate wickedness of the blacks, and the benefit they derived from their state of slavery among the christians! the mildness of spanish legislation, compared with the black code of most other nations that have possessions in either of the indies, cannot be denied. but such is the state of the negroes, that justice, far from efficaciously protecting them during their lives, cannot even punish acts of barbarity which cause their death. the road we took across the forest of catuaro resembled the descent of the mountain santa maria; here also, the most difficult and dangerous places have fanciful names. we walked as in a narrow furrow, scooped out by torrents, and filled with fine tenacious clay. the mules lowered their cruppers and slid down the steepest slopes. this descent is called saca manteca.* (* or the butter-slope. manteca in spanish signifies butter.) there is no danger in the descent, owing to the great address of the mules of this country. the clay, which renders the soil so slippery, is produced by the numerous layers of sandstone and schistose clay crossing the bluish grey alpine limestone. this last disappears as we draw nearer to cariaco. when we reached the mountain of meapira, we found it formed in great part of a white limestone, filled with fossil remains, and from the grains of quartz agglutinated in the mass, it appeared to belong to the great formation of the sea-coast breccias. we descended this mountain on the strata of the rock, the section of which forms steps of unequal height. farther on, going out of the forest, we reached the hill of buenavista,* (* mountain of the fine prospect.) well deserving the name it bears; since it commands a view of the town of cariaco, situated in the midst of a vast plain filled with plantations, huts, and scattered groups of cocoa-palms. to the west of cariaco extends the wide gulf; which a wall of rock separates from the ocean: and towards the east are seen, like bluish clouds, the high mountains of paria and areo. this is one of the most extensive and magnificent prospects that can be enjoyed on the coast of new andalusia. in the town of cariaco we found a great part of the inhabitants suffering from intermittent fever; a disease which in autumn assumes a formidable character. when we consider the extreme fertility of the surrounding plains, their moisture, and the mass of vegetation with which they are covered, we may easily conceive why, amidst so much decomposition of organic matter, the inhabitants do not enjoy that salubrity of air which characterizes the climate of cumana. the chain of calcareous mountains of the brigantine and the cocollar sends off a considerable branch to the north, which joins the primitive mountains of the coast. this branch bears the name of sierra de meapire; but towards the town of cariaco it is called cerro grande de curiaco. its mean height did not appear to be more than or toises. it was composed, where i could examine it, of the calcareous breccias of the sea-coast. marly and calcareous beds alternate with other beds containing grains of quartz. it is a very striking phenomenon for those who study the physical aspect of a country, to see a transverse ridge connect at right angles two parallel ridges, of which one, the more southern, is composed of secondary rocks, and the other, the more northern, of primitive rocks. the latter presents, nearly as far as the meridian of carupano, only mica-slate; but to the east of this point, where it communicates by a transverse ridge (the sierra de meapire) with the limestone range, it contains lamellar gypsum, compact limestone, and other rocks of secondary formation. it might be supposed that the southern ridge has transferred these rocks to the northern chain. when standing on the summit of the cerro del meapire, we see the mountain currents flow on one side to the gulf of paria, and on the other to the gulf of cariaco. east and west of the ridge there are low and marshy grounds, spreading out without interruption; and if it be admitted that both gulfs owe their origin to the sinking of the earth, and to rents caused by earthquakes, we must suppose that the cerro de meapire has resisted the convulsive movements of the globe, and hindered the waters of the gulf of paria from uniting with those of the gulf of cariaco. but for this rocky dyke, the isthmus itself in all probability would have had no existence; and from the castle of araya as far as cape paria, the whole mass of the mountains of the coast would have formed a narrow island, parallel to the island of santa margareta, and four times as long. not only do the inspection of the ground, and considerations deduced from its relievo, confirm these opinions; but a mere glance of the configuration of the coasts, and a geological map of the country, would suggest the same ideas. it would appear that the island of margareta has been heretofore attached to the coast-chain of araya by the peninsula of chacopata and the caribbee islands, lobo and coche, in the same manner as this chain is still connected with that of the cocollar and caripe by the ridge of meapire. at present we perceive that the humid plains which stretch east and west of the ridge, and which are improperly called the valleys san bonifacio and cariaco, are enlarging by gaining on the sea. the waters are receding, and these changes of the shore are very remarkable, more particularly on the coast of cumana. if the level of the soil seem to indicate that the two gulfs of cariaco and paria formerly occupied a much more considerable space, we cannot doubt that at present the land is progressively extending. near cumana, a battery, called la boca, was built in on the very margin of the sea; in we saw it very far inland. at the mouth of the rio neveri, near the morro of nueva barcelona, the retreat of the waters is still more rapid. this local phenomenon is probably assignable to accumulations of sand, the progress of which has not yet been sufficiently examined. descending the sierra de meapire, which forms the isthmus between the plains of san bonifacio and cariaco, we find towards the east the great lake of putacuao, which communicates with the river areo, and is four or five leagues in diameter. the mountainous lands that surround this basin are known only to the natives. there are found those great boa serpents known to the chayma indians by the name of guainas, and to which they fabulously attribute a sting under the tail. descending the sierra de meapire to the west, we find at first a hollow ground (tierra hueca) which, during the great earthquakes of , threw out asphaltum enveloped in viscous petroleum. farther on, a numberless quantity of sulphureous thermal springs* are seen issuing from the soil (* el llano de aguas calientes, east-north-east of cariaco, at the distance of two leagues.); and at length we reach the borders of the lake of campoma, the exhalations from which contribute to the insalubrity of the climate of cariaco. the natives believe that the hollow is formed by the engulfing of the hot springs; and, judging from the sound heard under the hoofs of the horses, we must conclude that the subterranean cavities are continued from west to east nearly as far as casanay, a length of three or four thousand toises. a little river, the rio azul, runs through these plains which are rent into crevices by earthquakes. these earthquakes have a particular centre of action, and seldom extend as far as cumana. the waters of the rio azul are cold and limpid; they rise on the western declivity of the mountain of meapire, and it is believed that they are augmented by infiltrations from the lake putacuao, situated on the other side of the chain. the little river, together with the sulphureous hot springs, fall into the laguna de campoma. this is a name given to a great lagoon, which is divided in dry weather into three basins situated north-west of the town of cariaco, near the extremity of the gulf. fetid exhalations arise continually from the stagnant water of this lagoon. the smell of sulphuretted hydrogen is mingled with that of putrid fishes and rotting plants. miasms are formed in the valley of cariaco, as in the campagna of rome; but the hot climate of the tropics increases their deleterious energy. these miasms are probably ternary or quaternary combinations of azote, phosphorus, hydrogen, carbon, and sulphur. the situation of the lagoon of campoma renders the north-west wind, which blows frequently after sunset, very pernicious to the inhabitants of the little town of cariaco. its influence can be the less doubted, as intermitting fevers are observed to degenerate into typhoid fevers, in proportion as we approach the lagoon, which is the principal focus of putrid miasms. whole families of free negroes, who have small plantations on the northern coast of the gulf of cariaco, languish in their hammocks from the beginning of the rainy season. these intermittent fevers assume a dangerous character, when persons, debilitated by long labour and copious perspiration, expose themselves to the fine rains, which frequently fall as evening advances. nevertheless, the men of colour, and particularly the creole negroes, resist much better than any other race, the influence of the climate. lemonade and infusions of scoparia dulcis are given to the sick; but the cuspare, which is the cinchona of angostura, is seldom used. it is generally observed, that in these epidemics of the town of cariaco the mortality is less considerable than might be supposed. intermitting fevers, when they attack the same individual during several successive years, enfeeble the constitution; but this state of debility, so common on the unhealthy coasts, does not cause death. what is remarkable enough, is the belief which prevails here as in the campagna of rome, that the air has become progressively more vitiated in proportion as a greater number of acres have been cultivated. the miasms exhaled from these plains have, however, nothing in common with those which arise from a forest when the trees are cut down, and the sun heats a thick layer of dead leaves. near cariaco the country is but thinly wooded. can it be supposed that the mould, fresh stirred and moistened by rains, alters and vitiates the atmosphere more than the thick wood of plants which covers an uncultivated soil? to local causes are joined other causes less problematic. the neighbouring shores of the sea are covered with mangroves, avicennias, and other shrubs with astringent bark. all the inhabitants of the tropics are aware of the noxious exhalations of these plants; and they dread them the more, as their roots and stocks are not always under water, but alternately wetted and exposed to the heat of the sun.* the mangroves produce miasms, because they contain vegeto-animal matter combined with tannin. (* the following is a list of the social plants that cover those sandy plains on the sea-side, and characterize the vegetation of cumana and the gulf of cariaco. rhizophora mangle, avicennia nitida, gomphrena flava, g. brachiata, sesuvium portulacastrum (vidrio), talinum cuspidatum (vicho), t. cumanense, portulacca pilosa (zargasso), p. lanuginosa, illecebrum maritimum, atriplex cristata, heliotropium viride, h. latifolium, verbena cuneata, mollugo verticillata, euphorbia maritima, convolvulus cumanensis.) the town of cariaco has been repeatedly sacked in former times by the caribs. its population has augmented rapidly since the provincial authorities, in spite of prohibitory orders from the court of madrid have often favoured the trade with foreign colonies. the population amounted, in , to more than souls. the inhabitants are active in the cultivation of cotton, which is of a very fine quality. the capsules of the cotton-tree, when separated from the woolly substance, are carefully burnt; as those husks if thrown into the river, and exposed to putrefaction, yield noxious exhalations. the culture of the cacao-tree has of late considerably diminished. this valuable tree bears only after eight or ten years. its fruit keeps very badly in the warehouses, and becomes mouldy at the expiration of a year, notwithstanding all the precautions employed for drying it. it is only in the interior of the province, to the east of the sierra de meapire, that new plantations of the cacao-tree are seen. they become there the more productive, as the lands, newly cleared and surrounded by forests, are in contact with an atmosphere damp, stagnant, and loaded with mephitic exhalations. we there see fathers of families, attached to the old habits of the colonists, slowly amass a little fortune for themselves and their children. thirty thousand cacao-trees will secure competence to a family for a generation and a half. if the culture of cotton and coffee have led to the diminution of cacao in the province of caracas and in the small valley of cariaco, it must be admitted that this last branch of colonial industry has in general increased in the interior of the provinces of new barcelona and cumana. the causes of the progressive movement of the cacao-tree from west to east may be easily conceived. the province of caracas has been from a remote period cultivated: and, in the torrid zone, in proportion as a country has been cleared, it becomes drier and more exposed to the winds. these physical changes have been adverse to the propagation of cacao-trees, the plantations of which, diminishing in the province of caracas, have accumulated eastward on a newly-cleared and virgin soil. the cacao of cumana is infinitely superior to that of guayaquil. the best is produced in the valley of san bonifacio; as the best cacao of new barcelona, caracas, and guatimala, is that of capiriqual, uritucu, and soconusco. since the island of trinidad has become an english colony, the whole of the eastern extremity of the province of cumana, especially the coast of paria, and the gulf of the same name, have changed their appearance. foreigners have settled there, and have introduced the cultivation of the coffee-tree, the cotton-tree, and the sugar-cane of otaheite. the population has greatly increased at carupano, in the beautiful valley of rio caribe, at guira, and at the new town of punta di piedra, built opposite spanish harbour, in the island of trinidad. the soil is so fertile in the golfo triste, that maize yields two harvests in the year, and produces three hundred and eighty fold the quantity sown. early in the morning we embarked in a sort of narrow canoe, called a lancha, in hopes of crossing the gulf of cariaco during the day. the motion of the waters resembles that of our great lakes, when they are agitated by the winds. from the embarcadero to cumana the distance is only twelve nautical leagues. on quitting the little town of cariaco, we proceeded westward along the river of carenicuar, which, in a straight line like an artificial canal, runs through gardens and plantations of cotton-trees. on the banks of the river of cariaco we saw the indian women washing their linen with the fruit of the parapara (sapindus saponaria, or soap-berry), an operation said to be very injurious to the linen. the bark of the fruit produces a strong lather; and the fruit is so elastic that if thrown on a stone it rebounds three or four times to the height of seven or eight feet. being a spherical form, it is employed in making rosaries. after we embarked we had to contend against contrary winds. the rain fell in torrents, and the thunder rolled very near. swarms of flamingoes, egrets, and cormorants filled the air, seeking the shore, whilst the alcatras, a large species of pelican, alone continued peaceably to fish in the middle of the gulf. the gulf of cariaco is almost everywhere forty-five or fifty fathoms deep; but at its eastern extremity, near curaguaca, along an extent of five leagues, the lead does not indicate more than three or four fathoms. here is found the baxo de la cotua, a sand-bank, which at low-water appears like a small island. the canoes which carry provisions to cumana sometimes ground on this bank; but always without danger, because the sea is never rough or heavy. we crossed that part of the gulf where hot springs gush from the bottom of the sea. it was flood-tide, so that the change of temperature was not very perceptible: besides, our canoe drove too much towards the southern shore. it may be supposed that strata of water must be found of different temperatures, according to the greater or less depth, and according as the mingling of the hot waters with those of the gulf is accelerated by the winds and currents. the existence of these hot springs, which we were assured raise the temperature of the sea through an extent of ten or twelve thousand square toises, is a very remarkable phenomenon. (* in the island of guadaloupe, there is a fountain of boiling water, which rushes out on the beach. hot-water springs rise from the bottom of the sea in the gulf of naples, and near the island of palma, in the archipelago of the canary islands.) proceeding from the promontory of paria westward, by irapa, aguas calientes, the gulf of cariaco, the brigantine, and the valley of aragua, as far as the snowy mountains of merida, a continued band of thermal waters is found in an extent of leagues. adverse winds and rainy weather forced us to go on shore at pericantral, a small farm on the south side of the gulf. the whole of this coast, though covered with beautiful vegetation, is almost wholly uncultivated. there are scarcely seven hundred inhabitants: and, excepting in the village of mariguitar, we saw only plantations of cocoa-trees, which are the olives of the country. this palm occupies on both continents a zone, of which the mean temperature of the year is not below degrees.* (* the cocoa-tree grows in the northern hemisphere from the equator to latitude degrees. near the equator we find it from the plains to the height of toises above the level of the sea.) it is, like the chamaerops of the basin of the mediterranean, a true palm-tree of the coast. it prefers salt to fresh water; and flourishes less inland, where the air is not loaded with saline particles, than on the shore. when cocoa-trees are planted in terra firma, or in the missions of the orinoco, at a distance from the sea, a considerable quantity of salt, sometimes as much as half a bushel, is thrown into the hole which receives the nut. among the plants cultivated by man, the sugar-cane, the plantain, the mammee-apple, and alligator-pear (laurus persea), alone have the property of the cocoa-tree; that of being watered equally well with fresh and salt water. this circumstance is favourable to their migrations; and if the sugarcane of the sea-shore yield a syrup that is a little brackish, it is believed at the same time to be better fitted for the distillation of spirit than the juice produced from the canes in inland situations. the cocoa-tree, in the other parts of america, is in general cultivated around farm-houses, and the fruit is eaten; in the gulf of cariaco, it forms extensive plantations. in a fertile and moist ground, the tree begins to bear fruit abundantly in the fourth year; but in dry soils it bears only at the expiration of ten years. the duration of the tree does not in general exceed eighty or a hundred years; and its mean height at that age is from seventy to eighty feet. this rapid growth is so much the more remarkable, as other palm-trees, for instance, the moriche,* (* mauritia flexuosa.) and the palm of sombrero,* (* corypha tectorum.) the longevity of which is very great, frequently do not attain a greater height than fourteen or eighteen feet in the space of sixty years. in the first thirty or forty years, a cocoa-tree of the gulf of cariaco bears every lunation a cluster of ten or fourteen nuts, all of which, however, do not ripen. it may be reckoned that, on an average, a tree produces annually a hundred nuts, which yield eight flascos* of oil. (one flasco contains or cubic inches, paris measure.) in provence, an olive-tree thirty years old yields twenty pounds, or seven flascos of oil, so that it produces something less than a cocoa-tree. there are in the gulf of cariaco plantations (haciendas) of eight or nine thousand cocoa-trees. they resemble, in their picturesque appearance, those fine plantations of date-trees near elche, in murcia, where, over the superficies of one square league, there may be found upwards of , palms. the cocoa-tree bears fruit in abundance till it is thirty or forty years old; after that age the produce diminishes, and a trunk a hundred years old, without being altogether barren, yields very little. in the town of cumana there is prepared a great quantity of cocoa-nut oil, which is limpid, without smell, and very fit for burning. the trade in this oil is not less active than that on the coast of africa for palm-oil, which is obtained from the elais guineensis, and is used as food. i have often seen canoes arrive at cumana laden with cocoa-nuts. we did not quit the farm of pericantral till after sunset. the south coast of the gulf presents a most fertile aspect, while the northern coast is naked, dry, and rocky. in spite of this aridity, and the scarcity of rain, of which sometimes none falls for the space of fifteen months,* the peninsula of araya, like the desert of canound in india, produces patillas, or water-melons, weighing from fifty to seventy pounds. (* the rains appear to have been more frequent at the beginning of the th century. at any rate, the canon of granada (peter martyr d'anghiera), speaking in the year , of the salt-works of araya, or of haraia, described in the fifth chapter of this work, mentions showers (cadentes imbres) as a very common phenomenon. the same author, who died in , affirms that the indians wrought the salt-works before the arrival of the spaniards. they dried the salt in the form of bricks; and our writer even then discussed the geological question, whether the clayey soil of haraia contained salt-springs, or whether it had been impregnated with salt by the periodical inundations of the ocean for ages.) in the torrid zone, the vapours contained by the air form about nine-tenths of the quantity necessary to its saturation: and vegetation is maintained by the property which the leaves possess of attracting the water dissolved in the atmosphere. at sunrise, we saw the zamuro vultures,* (* vultur aura.) in flocks of forty or fifty, perched on the cocoa-trees. these birds range themselves in files to roost together like fowls. they go to roost long before sunset, and do not awake till after the sun is above the horizon. this sluggishness seems as if it were shared in those climates by the trees with pinnate leaves. the mimosas and the tamarinds close their leaves, in a clear and serene sky, twenty-five or thirty-five minutes before sunset, and unfold them in the morning when the solar disk has been visible for an equal space of time. as i noticed pretty regularly the rising and setting of the sun, for the purpose of observing the effect of the mirage, or of the terrestrial refractions, i was enabled to give continued attention to the phenomena of the sleep of plants. i found them the same in the steppes, where no irregularity of the ground interrupted the view of the horizon. it appears, that, accustomed during the day to an extreme brilliancy of light, the sensitive and other leguminous plants with thin and delicate leaves are affected in the evening by the smallest decline in the intensity of the sun's rays; so that for vegetation, night begins there, as with us, before the total disappearance of the solar disk. but why, in a zone where there is scarcely any twilight, do not the first rays of the sun stimulate the leaves with the more strength, as the absence of light must have rendered them more susceptible? does the humidity deposited on the parenchyma by the cooling of the leaves, which is the effect of the nocturnal radiation, prevent the action of the first rays of the sun? in our climates, the leguminous plants with irritable leaves awake during the twilight of the morning, before the sun appears. chapter . . physical constitution and manners of the chaymas. their language. filiation of the nations which inhabit new andalucia. pariagotos seen by columbus. i did not wish to mingle with the narrative of our journey to the missions of caripe any general considerations on the different tribes of the indigenous inhabitants of new andalusia; their manners, their languages, and their common origin. having returned to the spot whence we set out, i shall now bring into one point of view these considerations which are so nearly connected with the history of the human race. as we advance into the interior of the country, these subjects will become even more interesting than the phenomena of the physical world. the north-east part of equinoctial america, terra firma, and the banks of the orinoco, resemble in respect to the numerous races of people who inhabit them, the defiles of the caucasus, the mountains of hindookho, at the northern extremity of asia, beyond the tungouses, and the tartare settled at the mouth of the lena. the barbarism which prevails throughout these different regions is perhaps less owing to a primitive absence of all kind of civilization, than to the effects of long degradation; for most of the hordes which we designate under the name of savages, are probably the descendants of nations highly advanced in cultivation. how can we distinguish the prolonged infancy of the human race (if, indeed, it anywhere exists), from that state of moral degradation in which solitude, want, compulsory misery, forced migration, or rigour of climate, obliterate even the traces of civilization? if everything connected with the primitive state of man, and the first population of a continent, could from its nature belong to the domain of history, we might appeal to the traditions of india. according to the opinion frequently expressed in the laws of menou and in the ramajan, savages were regarded as tribes banished from civilized society, and driven into the forests. the word barbarian, which we have borrowed from the greeks and romans, was possibly merely the proper name of one of those rude hordes. in the new world, at the beginning of the conquest, the natives were collected into large societies only on the ridge of the cordilleras and the coasts opposite to asia. the plains, covered with forests, and intersected by rivers; the immense savannahs, extending eastward, and bounding the horizon; were inhabited by wandering hordes, separated by differences of language and manners, and scattered like the remnants of a vast wreck. in the absence of all other monuments, we may endeavour, from the analogy of languages, and the study of the physical constitution of man, to group the different tribes, to follow the traces of their distant emigrations, and to discover some of those family features by which the ancient unity of our species is manifested. in the mountainous regions which we have just traversed,--in the two provinces of cumana and new barcelona, the natives, or primitive inhabitants, still constitute about one-half of the scanty population. their number may be reckoned at sixty thousand; of which twenty-four thousand inhabit new andalusia. this number is very considerable, when compared with that of the hunting nations of north america; but it appears small, when we consider those parts of new spain in which agriculture has existed more than eight centuries: for instance, the intendencia of oaxaca, which includes the mixteca and the tzapoteca of the old mexican empire. this intendencia is one-third smaller than the two provinces of cumana and barcelona; yet it contains more than four hundred thousand natives of pure copper-coloured race. the indians of cumana do not all live within the missions. some are dispersed in the neighbourhood of the towns, along the coasts, to which they are attracted by the fisheries, and some dwell in little farms on the plains or savannahs. the missions of the aragonese capuchins which we visited, alone contain fifteen thousand indians, almost all of the chayma race. the villages, however, are less populous there than in the province of barcelona. their average population is only between five or six hundred indians; while more to the west, in the missions of the franciscans of piritu, we find indian villages containing two or three thousand inhabitants. in computing at sixty thousand the number of natives in the provinces of cumana and barcelona, i include only those who inhabit the mainland, and not the guayquerias of the island of margareta, and the great mass of the guaraunos, who have preserved their independence in the islands formed by the delta of the orinoco. the number of these is generally reckoned at six or eight thousand; but this estimate appears to me to be exaggerated. except a few families of guaraunos who roam occasionally in the marshy grounds, called los morichales, and between the cano de manamo and the rio guarapiche, consequently, on the continent itself, there have not been for these thirty years, any indian savages in new andalusia. i use with regret the word savage, because it implies a difference of cultivation between the reduced indian, living in the missions, and the free or independent indian; a difference which is often belied by fact. in the forests of south america there are tribes of natives, peacefully united in villages, and who render obedience to chiefs.* (* these chiefs bear the designations of pecannati, apoto, or sibierne.) they cultivate the plantain-tree, cassava, and cotton, on a tolerably extensive tract of ground, and they employ the cotton for weaving hammocks. these people are scarcely more barbarous than the naked indians of the missions, who have been taught to make the sign of the cross. it is a common error in europe, to look on all natives not reduced to a state of subjection, as wanderers and hunters. agriculture was practised on the american continent long before the arrival of europeans. it is still practised between the orinoco and the river amazon, in lands cleared amidst the forests, places to which the missionaries have never penetrated. it would be to imbibe false ideas respecting the actual condition of the nations of south america, to consider as synonymous the denominations of 'christian,' 'reduced,' and 'civilized;' and those of 'pagan,' 'savage,' and 'independent.' the reduced indian is often as little of a christian as the independent indian is of an idolater. both, alike occupied by the wants of the moment, betray a marked indifference for religious sentiments, and a secret tendency to the worship of nature and her powers. this worship belongs to the earliest infancy of nations; it excludes idols, and recognises no other sacred places than grottoes, valleys, and woods. if the independent indians have nearly disappeared for a century past northward of the orinoco and the apure, that is, from the snowy mountains of merida to the promontory of paria, it must not thence be concluded, that there are fewer natives at present in those regions, than in the time of the bishop of chiapa, bartolomeo de las casas. in my work on mexico, i have shown that it is erroneous to regard as a general fact the destruction and diminution of the indians in the spanish colonies. there still exist more than six millions of the copper-coloured race, in both americas; and, though numberless tribes and languages are either extinct, or confounded together, it is beyond a doubt that, within the tropics, in that part of the new world where civilization has penetrated only since the time of columbus, the number of natives has considerably increased. two of the carib villages in the missions of piritu or of carony, contain more families than four or five of the settlements on the orinoco. the state of society among the caribbees who have preserved their independence, at the sources of the essequibo and to the south of the mountains of pacaraimo, sufficiently proves how much, even among that fine race of men, the population of the missions exceeds in number that of the free and confederate caribbees. besides, the state of the savages of the torrid zone is not like that of the savages of the missouri. the latter require a vast extent of country, because they live only by hunting; whilst the indians of spanish guiana employ themselves in cultivating cassava and plantains. a very little ground suffices to supply them with food. they do not dread the approach of the whites, like the savages of the united states; who, being progressively driven back behind the alleghany mountains, the ohio, and the mississippi, lose their means of subsistence, in proportion as they find themselves reduced within narrow limits. under the temperate zone, whether in the provincias internas of mexico, or in kentucky, the contact of european colonists has been fatal to the natives, because that contact is immediate. these causes have no existence in the greater part of south america. agriculture, within the tropics, does not require great extent of ground. the whites advance slowly. the religious orders have founded their establishments between the domain of the colonists and the territory of the free indians. the missions may be considered as intermediary states. they have doubtless encroached on the liberty of the natives; but they have almost everywhere tended to the increase of population, which is incompatible with the restless life of the independent indians. as the missionaries advance towards the forests, and gain on the natives, the white colonists in their turn seek to invade in the opposite direction the territory of the missions. in this protracted struggle, the secular arm continually tends to withdraw the reduced indian from the monastic hierarchy, and the missionaries are gradually superseded by vicars. the whites, and the castes of mixed blood, favoured by the corregidors, establish themselves among the indians. the missions become spanish villages, and the natives lose even the remembrance of their natural language. such is the progress of civilization from the coasts toward the interior; a slow progress, retarded by the passions of man, but nevertheless sure and steady. the provinces of new andalusia and barcelona, comprehended under the name of govierno de cumana, at present include in their population more than fourteen tribes. those in new andalusia are the chaymas, guayqueries, pariagotos, quaquas, aruacas, caribbees, and guaraunos; in the province of barcelona, cumanagotos, palenkas, caribbees, piritus, tomuzas, topocuares, chacopatas, and guarivas. nine or ten of these fifteen tribes consider themselves to be of races entirely distinct. the exact number of the guaraunos, who make their huts on the trees at the mouth of the orinoco, is unknown; the guayqueries, in the suburbs of cumana and in the peninsula of araya, amount to two thousand. among the other indian tribes, the chaymas of the mountains of caripe, the caribs of the southern savannahs of new barcelona, and the cumanagotos in the missions of piritu, are most numerous. some families of guaraunos have been reduced and dwell in missions on the left bank of the orinoco, where the delta begins. the languages of the guaraunos and that of the caribs, of the cumanagotos and of the chaymas, are the most general. they seem to belong to the same stock; and they exhibit in their grammatical forms those affinities, which, to use a comparison taken from languages more known, connect the greek, the german, the persian, and the sanscrit. notwithstanding these affinities, we must consider the chaymas, the guaraunos, the caribbees, the quaquas, the aruacas or arrawaks, and the cumanagotos, as different nations. i would not venture to affirm the same of the guayqueries, the pariagotos, the piritus, the tomuzas, and the chacopatas. the guayquerias themselves admit the analogy between their language and that of the guaraunos. both are a littoral race, like the malays of the ancient continent. with respect to the tribes who at present speak the cumanagota, caribbean, and chayma tongues, it is difficult to decide on their first origin, and their relations with other nations formerly more powerful. the historians of the conquest, as well as the ecclesiastics who have described the progress of the missions, continually confound, like the ancients, geographical denominations with the names of races. they speak of indians of cumana and of the coast of paria, as if the proximity of abode proved the identity of origin. they most commonly even give to tribes the names of their chiefs, or of the mountains or valleys they inhabit. this circumstance, by infinitely multiplying the number of tribes, gives an air of uncertainty to all that the monks relate respecting the heterogeneous elements of which the population of their missions are composed. how can we now decide, whether the tomuza and piritu be of different races, when both speak the cumanagoto language, which is the prevailing tongue in the western part of the govierno of cumana; as the caribbean and the chayma are in the southern and eastern parts. a great analogy of physical constitution increases the difficulty of these inquiries. in the new continent a surprising variety of languages is observed among nations of the same origin, and which european travellers scarcely distinguish by their features; while in the old continent very different races of men, the laplanders, the finlanders, and the estonians, the germanic nations and the hindoos, the persians and the kurds, the tartar and mongol tribes, speak languages, the mechanism and roots of which present the greatest analogy. the indians of the american missions are all agriculturists. excepting those who inhabit the high mountains, they all cultivate the same plants; their huts are arranged in the same manner; their days of labour, their work in the conuco of the community; their connexions with the missionaries and the magistrates chosen from among themselves, are all subject to uniform regulations. nevertheless (and this fact is very remarkable in the history of nations), these analogous circumstances have not effaced the individual features, or the shades of character which distinguish the american tribes. we observe in the men of copper hue, a moral inflexibility, a steadfast perseverance in habits and manners, which, though modified in each tribe, characterise essentially the whole race. these peculiarities are found in every region; from the equator to hudson's bay on the one hand, and to the straits of magellan on the other. they are connected with the physical organization of the natives, but they are powerfully favoured by the monastic system. there exist in the missions few villages in which the different families do not belong to different tribes and speak different languages. societies composed of elements thus heterogeneous are difficult to govern. in general, the monks have united whole nations, or great portions of the same nations, in villages situated near to each other. the natives see only those of their own tribe; for the want of communication, and the isolated state of the people, are essential points in the policy of the missionaries. the reduced chaymas, caribs, and tamanacs, retain their natural physiognomy, whilst they have preserved their languages. if the individuality of man be in some sort reflected in his idioms, these in their turn re-act on his ideas and sentiments. it is this intimate connection between language, character, and physical constitution, which maintains and perpetuates the diversity of nations; that unfailing source of life and motion in the intellectual world. the missionaries may have prohibited the indians from following certain practices and observing certain ceremonies; they may have prevented them from painting their skin, from making incisions on their chins, noses and cheeks; they may have destroyed among the great mass of the people superstitious ideas, mysteriously transmitted from father to son in certain families; but it has been easier for them to proscribe customs and efface remembrances, than to substitute new ideas in the place of the old ones. the indian of the mission is secure of subsistence; and being released from continual struggles against hostile powers, from conflicts with the elements and man, he leads a more monotonous life, less active, and less fitted to inspire energy of mind, than the habits of the wild or independent indian. he possesses that mildness of character which belongs to the love of repose; not that which arises from sensibility and the emotions of the soul. the sphere of his ideas is not enlarged, where, having no intercourse with the whites, he remains a stranger to those objects with which european civilization has enriched the new world. all his actions seem prompted by the wants of the moment. taciturn, serious, and absorbed in himself; he assumes a sedate and mysterious air. when a person has resided but a short time in the missions, and is but little familiarized with the aspect of the natives, he is led to mistake their indolence, and the torpid state of their faculties, for the expression of melancholy, and a meditative turn of mind. i have dwelt on these features of the indian character, and on the different modifications which that character exhibits under the government of the missionaries, with the view of rendering more intelligible the observations which form the subject of the present chapter. i shall begin by the nation of the chaymas, of whom more than fifteen thousand inhabit the missions above noticed. the chayma nation, which father francisco of pampeluna* began to reduce to subjection in the middle of the seventeenth century (* the name of this monk, celebrated for his intrepidity, is still revered in the province. he sowed the first seeds of civilization among these mountains. he had long been captain of a ship; and before he became a monk, was known by the name of tiburtio redin.), has the cumanagotos on the west, the guaraunos on the east, and the caribbees on the south. their territory occupies a space along the elevated mountains of the cocollar and the guacharo, the banks of the guarapiche, of the rio colorado, of the areo, and of the cano de caripe. according to a statistical survey made with great care by the father prefect, there were, in the missions of the aragonese capuchins of cumana, nineteen mission villages, of which the oldest was established in , containing one thousand four hundred and sixty-five families, and six thousand four hundred and thirty-three persons: sixteen doctrina villages, of which the oldest dates from , containing one thousand seven hundred and sixty-six families, and eight thousand one hundred and seventy persons. these missions suffered greatly in , , and , from the invasions of the caribbees (then independent), who burnt whole villages. from to , the population was diminished by the ravages of the small-pox, a disease always more fatal to the copper-coloured indians than to the whites. many of the guaraunos, who had been assembled together, fled back again to their native marshes. fourteen old missions were deserted, and have not been rebuilt. the chaymas are in general short of stature and thick-set. their shoulders are extremely broad, and their chests flat. their limbs are well rounded, and fleshy. their colour is the same as that of the whole american race, from the cold table-lands of quito and new grenada to the burning plains of the amazon. it is not changed by the varied influence of climate; it is connected with organic peculiarities which for ages past have been unalterably transmitted from generation to generation. if the uniform tint of the skin be redder and more coppery towards the north, it is, on the contrary, among the chaymas, of a dull brown inclining to tawny. the denomination of copper-coloured men could never have originated in equinoctial america to designate the natives. the expression of the countenance of the chaymas, without being hard or stern, has something sedate and gloomy. the forehead is small, and but little prominent, and in several languages of these countries, to express the beauty of a woman, they say that 'she is fat, and has a narrow forehead.' the eyes of the chaymas are black, deep-set, and very elongated: but they are neither so obliquely placed, nor so small, as in the people of the mongol race. the corner of the eye is, however, raised up towards the temple; the eyebrows are black, or dark brown, thin, and but little arched; the eyelids are edged with very long eyelashes, and the habit of casting them down, as if from lassitude, gives a soft expression to the women, and makes the eye thus veiled appear less than it really is. though the chaymas, and in general all the natives of south america and new spain, resemble the mongol race in the form of the eye, in their high cheek-bones, their straight and smooth hair, and the almost total absence of beard; yet they essentially differ from them in the form of the nose. in the south americans this feature is rather long, prominent through its whole length, and broad at the nostrils, the openings of which are directed downward, as with all the nations of the caucasian race. their wide mouths, with lips but little protuberant though broad, have generally an expression of good nature. the passage from the nose to the mouth is marked in both sexes by two furrows, which run diverging from the nostrils towards the corners of the mouth. the chin is extremely short and round; and the jaws are remarkable for strength and width. though the chaymas have fine white teeth, like all people who lead a very simple life, they are, however, not so strong as those of the negroes. the habit of blackening the teeth, from the age of fifteen, by the juices of certain herbs* and caustic lime, attracted the attention of the earliest travellers; but the practice has now fallen quite into disuse. (* the early historians of the conquest state that the blackening of the teeth was effected by the leaves of a tree which the natives called hay, and which resembled the myrtle. among nations very distant from each other, the pimento bears a similar name; among the haitians aji or ahi, among the maypures of the orinoco, ai. some stimulant and aromatic plants, which mostly belonging to the genus capsicum, were designated by the same name.) such have been the migrations of the different tribes in these countries, particularly since the incursions of the spaniards, who carried on the slave-trade, that it may be inferred the inhabitants of paria visited by christopher columbus and by ojeda, were not of the same race as the chaymas. i doubt much whether the custom of blackening the teeth was originally suggested, as gomara supposed, by absurd notions of beauty, or was practised with the view of preventing the toothache. * this disorder is, however, almost unknown to the indians; and the whites suffer seldom from it in the spanish colonies, at least in the warm regions, where the temperature is so uniform. they are more exposed to it on the back of the cordilleras, at santa fe, and at popayan. (* the tribes seen by the spaniards on the coast of paria, probably observed the practice of stimulating the organs of taste by caustic lime, as other races employed tobacco, the chimo, the leaves of the coca, or the betel. this practice exists even in our days, but more towards the west, among the guajiros, at the mouth of the rio de la hacha. these indians, still savage, carry small shells, calcined and powdered, in the husk of a fruit, which serves them as a vessel for various purposes, suspended to their girdle. the powder of the guajiros is an article of commerce, as was anciently, according to gomara, that of the indians of paria. the immoderate habit of smoking also makes the teeth yellow and blackens them; but would it be just to conclude from this fact, that europeans smoke because we think yellow teeth handsomer than white?) the chaymas, like almost all the native nations i have seen, have small, slender hands. their feet are large, and their toes retain an extraordinary mobility. all the chaymas have a sort of family look; and this resemblance, so often observed by travellers, is the more striking, as between the ages of twenty and fifty, difference of years is no way denoted by wrinkles of the skin, colour of the hair, or decrepitude of the body. on entering a hut, it is often difficult among adult persons to distinguish the father from the son, and not to confound one generation with another. i attribute this air of family resemblance to two different causes, the local situation of the indian tribes, and their inferior degree of intellectual culture. savage nations are subdivided into an infinity of tribes, which, bearing violent hatred one to another, form no intermarriages, even when their languages spring from the same root, and when only a small arm of a river, or a group of hills, separates their habitations. the less numerous the tribes, the more the intermarriages repeated for ages between the same families tend to fix a certain similarity of conformation, an organic type, which may be called national. this type is preserved under the system of the missions, each mission being formed by a single horde, and marriages being contracted only between the inhabitants of the same hamlet. those ties of blood which unite almost a whole nation, are indicated in a simple manner in the language of the indians born in the missions, or by those who, after having been taken from the woods, have learned spanish. to designate the individuals who belong to the same tribe, they employ the expression mis parientes, my relations. with these causes, common to all isolated classes, and the effects of which are observable among the jews of europe, among the different castes of india, and among mountain nations in general, are combined some other causes hitherto unnoticed. i have observed elsewhere, that it is intellectual culture which most contributes to diversify the features. barbarous nations have a physiognomy of tribe or of horde, rather than individuality of look or features. the savage and civilized man are like those animals of an individual species, some of which roam in the forest, while others, associated with mankind, share the benefits and evils which accompany civilization. varieties of form and colour are frequent only in domestic animals. how great is the difference, with respect to mobility of features and variety of physiognomy, between dogs which have again returned to the savage state in the new world, and those whose slightest caprices are indulged in the houses of the opulent! both in men and animals the emotions of the soul are reflected in the features; and the countenance acquires the habit of mobility, in proportion as the emotions of the mind are frequent, varied, and durable. but the indian of the missions, being remote from all cultivation, influenced only by his physical wants, satisfying almost without difficulty his desires, in a favoured climate, drags on a dull, monotonous life. the greatest equality prevails among the members of the same community; and this uniformity, this sameness of situation, is pictured on the features of the indians. under the system of the monks, violent passions, such as resentment and anger, agitate the native more rarely than when he lives in the forest. when man in a savage state yields to sudden and impetuous emotions, his physiognomy, till then calm and unruffled, changes instantly to convulsive contortions. his passion is transient in proportion to its violence. with the indians of the missions, as i have often observed on the orinoco, anger is less violent, less earnest, but of longer duration. besides, in every condition of man, it is not the energetic or the transient outbreaks of the passions, which give expression to the features. it is rather that sensibility of the soul, which brings us continually into contact with the external world, multiplies our sufferings and our pleasures, and re-acts at once on the physiognomy, the manners, and the language. if the variety and mobility of the features embellish the domain of animated nature, we must admit also, that both increase by civilization, without being solely produced by it. in the great family of nations, no other race unites these advantages in so high a degree as the caucasian or european. it is only in white men that the instantaneous penetration of the dermoidal system by the blood can produce that slight change of the colour of the skin which adds so powerful an expression to the emotions of the soul. "how can those be trusted who know not how to blush?" says the european, in his dislike of the negro and the indian. we must also admit, that immobility of features is not peculiar to every race of men of dark complexion: it is much less marked in the african than in the natives of america. the chaymas, like all savage people who dwell in excessively hot regions, have an insuperable aversion to clothing. the writers of the middle ages inform us, that in the north of europe, articles of clothing distributed by missionaries, greatly contributed to the conversion of the pagan. in the torrid zone, on the contrary, the natives are ashamed (as they say) to be clothed; and flee to the woods, when they are compelled to cover themselves. among the chaymas, in spite of the remonstrances of the monks, men and women remain unclothed within their houses. when they go into the villages they put on a kind of tunic of cotton, which scarcely reaches to the knees. the men's tunics have sleeves; but women, and young boys to the age of ten or twelve, have the arms, shoulders, and upper part of the breast uncovered. the tunic is so shaped, that the fore-part is joined to the back by two narrow bands, which cross the shoulders. when we met the natives, out of the boundaries of the mission, we saw them, especially in rainy weather, stripped of their clothes, and holding their shirts rolled up under their arms. they preferred letting the rain fall on their bodies to wetting their clothes. the elder women hid themselves behind trees, and burst into loud fits of laughter when they saw us pass. the missionaries complain that in general the young girls are not more alive to feelings of decency than the men. ferdinand columbus* relates that, in , his father found the women in the island of trinidad without any clothing (* life of the adelantado: churchill's collection . this life, written after the year , from original notes in the handwriting of christopher columbus himself, is the most valuable record of the history of his discoveries. it exists only in the italian and spanish translations of alphonso de ulloa and gonzales barcia: for the original, carried to venice in by the learned fornari, has not been published, and is supposed to be lost. napione della patria di colombo . cancellieri sopra christ. colombo . ); while the men wore the guayuco, which is rather a narrow bandage than an apron. at the same period, on the coast of paria, young girls were distinguished from married women, either, as cardinal bembo states, by being quite unclothed, or, according to gomara, by the colour of the guayuco. this bandage, which is still in use among the chaymas, and all the naked nations of the orinoco, is only two or three inches broad, and is tied on both sides to a string which encircles the waist. girls are often married at the age of twelve; and until they are nine years old, the missionaries allow them to go to church unclothed, that is to say, without a tunic. among the chaymas, as well as in all the spanish missions and the indian villages, a pair of drawers, a pair of shoes, or a hat, are objects of luxury unknown to the natives. an indian servant, who had been with us during our journey to caripe and the orinoco, and whom i brought to france, was so much struck, on landing, when he saw the ground tilled by a peasant with his hat on, that he thought himself in a miserable country, where even the nobles (los mismos caballeros) followed the plough. the chayma women are not handsome, according to the ideas we annex to beauty; yet the young girls have a look of softness and melancholy, contrasting agreeably with the expression of the mouth, which is somewhat harsh and wild. they wear their hair plaited in two long tresses; they do not paint their skin; and wear no other ornaments than necklaces and bracelets made of shells, birds' bones, and seeds. both men and women are very muscular, but at the same time fleshy and plump. i saw no person who had any natural deformity; and i may say the same of thousands of caribs, muyscas, and mexican and peruvian indians, whom we observed during the course of five years. bodily deformities, and deviations from nature, are exceedingly rare among certain races of men, especially those who have the epidermis highly coloured; but i cannot believe that they depend solely on the progress of civilization, a luxurious life, or the corruption of morals. in europe a deformed or very ugly girl marries, if she happen to have a fortune, and the children often inherit the deformity of the mother. in the savage state, which is a state of equality, no consideration can induce a man to unite himself to a deformed woman, or one who is very unhealthy. such a woman, if she resist the accidents of a restless and troubled life, dies without children. we might be tempted to think, that savages all appear well-made and vigorous, because feeble children die young for want of care, and only the strongest survive; but these causes cannot operate among the indians of the missions, whose manners are like those of our peasants, or among the mexicans of cholula and tlascala, who enjoy wealth, transmitted to them by ancestors more civilized than themselves. if, in every state of cultivation, the copper-coloured race manifests the same inflexibility, the same resistance to deviation from a primitive type, are we not forced to admit that this peculiarity belongs in great measure to hereditary organization, to that which constitutes the race? with copper-coloured men, as with whites, luxury and effeminacy weaken the physical constitution, and heretofore deformities were more common at cuzco and tenochtitlan. among the mexicans of the present day, who are all labourers, leading the most simple lives, montezuma would not have found those dwarfs and humpbacks whom bernal diaz saw waiting at his table when he dined.* (* bernal diaz hist. verd. de la nueva espana .) the custom of marrying very young, according to the testimony of the monks, is no way detrimental to population. this precocious nubility depends on the race, and not on the influence of a climate excessively warm. it is found on the north-west coast of america, among the esquimaux, and in asia, among the kamtschatdales, and the koriaks, where girls of ten years old are often mothers. it may appear astonishing, that the time of gestation--the duration of pregnancy, never alters in a state of health, in any race, or in any climate. the chaymas are almost without beard on the chin, like the tungouses, and other nations of the mongol race. they pluck out the few hairs which appear; but independently of that practice, most of the natives would be nearly beardless.* (* physiologists would never have entertained any difference of opinion respecting the existence of the beard among the americans, if they had considered what the first historians of the conquest have said on this subject; for example, pigafetta, in , in his journal, preserved in the ambrosian library at milan, and published (in ) by amoretti; benzoni hist. del mundo nuovo ; bembo hist. venet. .) i say most of them, because there are tribes which, as they appear distinct from the others, are more worthy of fixing our attention. such are, in north america, the chippewas visited by mackenzie, and the yabipaees, near the toltec ruins at moqui, with bushy beards; in south america, the patagonians and the guaraunos. among these last are some who have hairs on the breast. when the chaymas, instead of extracting the little hair they have on the chin, attempt to shave themselves frequently, their beards grow. i have seen this experiment tried with success by young indians, who officiated at mass, and who anxiously wished to resemble the capuchin fathers, their missionaries and masters. the great mass of the people, however, dislike the beard, no less than the eastern nations hold it in reverence. this antipathy is derived from the same source as the predilection for flat foreheads, which is evinced in so singular a manner in the statues of the aztec heroes and divinities. nations attach the idea of beauty to everything which particularly characterizes their own physical conformation, their national physiognomy.* (* thus, in their finest statues, the greeks exaggerated the form of the forehead, by elevating beyond proportion the facial line.) hence it ensues that among a people to whom nature has given very little beard, a narrow forehead, and a brownish red skin, every individual thinks himself handsome in proportion as his body is destitute of hair, his head flattened, and his skin besmeared with annatto, chica, or some other copper-red colour. the chaymas lead a life of singular uniformity. they go to rest very regularly at seven in the evening, and rise long before daylight, at half-past four in the morning. every indian has a fire near his hammock. the women are so chilly, that i have seen them shiver at church when the centigrade thermometer was not below degrees. the huts of the indians are extremely clean. their hammocks, their reed mats, their pots for holding cassava and fermented maize, their bows and arrows, everything is arranged in the greatest order. men and women bathe every day; and being almost constantly unclothed, they are exempted from that uncleanliness, of which the garments are the principal cause among the lower class of people in cold countries. besides a house in the village, they have generally, in their conucos, near some spring, or at the entrance of some solitary valley, a small hut, covered with the leaves of the palm or plantain-tree. though they live less commodiously in the conuco, they love to retire thither as often as they can. the irresistible desire the indians have to flee from society, and enter again on a nomad life, causes even young children sometimes to leave their parents, and wander four or five days in the forests, living on fruits, palm-cabbage, and roots. when travelling in the missions, it is not uncommon to find whole villages almost deserted, because the inhabitants are in their gardens, or in the forests (al monte). among civilized nations, the passion for hunting arises perhaps in part from the same causes: the charm of solitude, the innate desire of independence, the deep impression made by nature, whenever man finds himself in contact with her in solitude. the condition of the women among the chaymas, like that in all semi-barbarous nations, is a state of privation and suffering. the hardest labour devolves on them. when we saw the chaymas return in the evening from their gardens, the man carried nothing but the knife or hatchet (machete), with which he clears his way among the underwood; whilst the woman, bending under a great load of plantains, carried one child in her arms, and sometimes two other children placed upon the load. notwithstanding this inequality of condition, the wives of the indians of south america appear to be in general happier than those of the savages of the north. between the alleghany mountains and the mississippi, wherever the natives do not live chiefly on the produce of the chase, the women cultivate maize, beans, and gourds; and the men take no share in the labours of the field. in the torrid zone, hunting tribes are not numerous, and in the missions, the men work in the fields as well as the women. nothing can exceed the difficulty experienced by the indians in learning spanish, to which language they have an absolute aversion. whilst living separate from the whites, they have no ambition to be called educated indians, or, to borrow the phrase employed in the missions, 'latinized indians' (indios muy latinos). not only among the chaymas, but in all the very remote missions which i afterwards visited, i observed that the indians experience vast difficulty in arranging and expressing the most simple ideas in spanish, even when they perfectly understand the meaning of the words and the turn of the phrases. when a european questions them concerning objects which have surrounded them from their cradles, they seem to manifest an imbecility exceeding that of infancy. the missionaries assert that this embarrassment is neither the effect of timidity nor of natural stupidity, but that it arises from the impediments they meet with in the structure of a language so different from their native tongue. in proportion as man is remote from cultivation, the greater is his mental inaptitude. it is not, therefore, surprising that the isolated indians in the missions should experience in the acquisition of the spanish language, less facility than indians who live among mestizoes, mulattoes, and whites, in the neighbourhood of towns. nevertheless, i have often wondered at the volubility with which, at caripe, the native alcalde, the governador, and the sergento mayor, will harangue for whole hours the indians assembled before the church; regulating the labours of the week, reprimanding the idle, or threatening the disobedient. those chiefs who are also of the chayma race, and who transmit the orders of the missionary, speak all together in a loud voice, with marked emphasis, but almost without action. their features remain motionless; but their look is imperious and severe. these same men, who manifest quickness of intellect, and who were tolerably well acquainted with the spanish, were unable to connect their ideas, when, in our excursions in the country around the convent, we put questions to them through the intervention of the monks. they were made to affirm or deny whatever the monks pleased: and that wily civility, to which the least cultivated indian is no stranger, induced them sometimes to give to their answers the turn that seemed to be suggested by our questions. travellers cannot be enough on their guard against this officious assent, when they seek to confirm their own opinions by the testimony of the natives. to put an indian alcalde to the proof, i asked him one day, whether he did not think the little river of caripe, which issues from the cavern of the guacharo, returned into it on the opposite side by some unknown entrance, after having ascended the slope of the mountain. the indian seemed gravely to reflect on the subject, and then answered, by way of supporting my hypothesis: "how else, if it were not so, would there always be water in the bed of the river at the mouth of the cavern?" the chaymas are very dull in comprehending anything relating to numerical facts. i never knew one of these people who might not have been made to say that he was either eighteen or sixty years of age. mr. marsden observed the same peculiarity in the malays of sumatra, though they have been civilized more than five centuries. the chayma language contains words which express pretty large numbers, yet few indians know how to apply them; and having felt, from their intercourse with the missionaries, the necessity of so doing, the more intelligent among them count in spanish, but apparently with great effort of mind, as far as thirty, or perhaps fifty. the same persons, however, cannot count in the chayma language beyond five or six. it is natural that they should employ in preference the words of a language in which they have been taught the series of units and tens. since learned europeans have not disdained to study the structure of the idioms of america with the same care as they study those of the semitic languages, and of the greek and latin, they no longer attribute to the imperfection of a language, what belongs to the rudeness of the nation. it is acknowledged, that almost everywhere the indian idioms display greater richness, and more delicate gradations, than might be supposed from the uncultivated state of the people by whom they are spoken. i am far from placing the languages of the new world in the same rank with the finest languages of asia and europe; but no one of these latter has a more neat, regular, and simple system of numeration, than the quichua and the aztec, which were spoken in the great empires of cuzco and anahuac. it is a mistake to suppose that those languages do not admit of counting beyond four, because in villages where they are spoken by the poor labourers of peruvian and mexican race, individuals are found, who cannot count beyond that number. the singular opinion, that so many american nations reckon only as far as five, ten, or twenty, has been propagated by travellers, who have not reflected, that, according to the genius of different idioms, men of all nations stop at groups of five, ten, or twenty units (that is, the number of the fingers of one hand, or of both hands, or of the fingers and toes together); and that six, thirteen, or twenty are differently expressed, by five-one, ten-three, and feet-ten.* (* savages, to express great numbers with more facility, are in the habit of forming groups of five, ten, or twenty grains of maize, according as they reckon in their language by fives, tens, or twenties.) can it be said that the numbers of the europeans do not extend beyond ten, because we stop after having formed a group of ten units? the construction of the languages of america is so opposite to that of the languages derived from the latin, that the jesuits, who had thoroughly examined everything that could contribute to extend their establishments, introduced among their neophytes, instead of the spanish, some indian tongues, remarkable for their regularity and copiousness, such as the quichua and the guarani. they endeavoured to substitute these languages for others which were poorer and more irregular in their syntax. this substitution was found easy: the indians of the different tribes adopted it with docility, and thenceforward those american languages generalized became a ready medium of communication between the missionaries and the neophytes. it would be a mistake to suppose, that the preference given to the language of the incas over the spanish tongue had no other aim than that of isolating the missions, and withdrawing them from the influence of two rival powers, the bishops and civil governors. the jesuits had other motives, independently of their policy, for wishing to generalize certain indian tongues. they found in those languages a common tie, easy to be established between the numerous hordes which had remained hostile to each other, and had been kept asunder by diversity of idioms; for, in uncultivated countries, after the lapse of several ages, dialects often assume the form, or at least the appearance, of mother tongues. when it is said that a dane learns the german, and a spaniard the italian or the latin, more easily than they learn any other language, it is at first thought that this facility results from the identity of a great number of roots, common to all the germanic tongues, or to those of latin europe; it is not considered, that, with this resemblance of sounds, there is another resemblance, which acts more powerfully on nations of a common origin. language is not the result of an arbitrary convention. the mechanism of inflections, the grammatical constructions, the possibility of inversions, all are the offspring of our own minds, of our individual organization. there is in man an instinctive and regulating principle, differently modified among nations not of the same race. a climate more or less severe, a residence in the defiles of mountains, or on the sea-coasts, or different habits of life, may alter the pronunciation, render the identity of the roots obscure, and multiply the number; but all these causes do not affect that which constitutes the structure and mechanism of languages. the influence of climate, and of external circumstances, vanishes before the influence which depends on the race, on the hereditary and individual dispositions of men. in america (and this result of recent researches* (* see vater's mithridates.) is extremely important with respect to the history of our species) from the country of the esquimaux to the banks of the orinoco, and again from these torrid regions to the frozen climate of the straits of magellan, mother-tongues, entirely different in their roots, have, if we may use the expression, the same physiognomy. striking analogies of grammatical construction are acknowledged, not only in the more perfect languages, as in that of the incas, the aymara, the guarauno, the mexican, and the cora, but also in languages extremely rude. idioms, the roots of which do not resemble each other more than the roots of the sclavonic and the biscayan, have those resemblances of internal mechanism which are found in the sanscrit, the persian, the greek, and the german languages. almost everywhere in the new world we recognize a multiplicity of forms and tenses in the verb,* (* in the greenland language, for example, the multiplicity of the pronouns governed by the verb produces twenty-seven forms for every tense of the indicative mood. it is surprising to find, among nations now ranking in the lowest degree of civilization, this desire of graduating the relations of time, this superabundance of modifications introduced into the verb, to characterise the object. matarpa, he takes it away: mattarpet, thou takest it away: mattarpatit, he takes it away from thee: mattarpagit, i take away from thee. and in the preterite of the same verb, mattara, he has taken it away: mattaratit, he has taken it away from thee. this example from the greenland language shows how the governed and the personal pronouns form one compound, in the american languages, with the root of the verb. these slight differences in the form of the verb, according to the nature of the pronouns governed by it, is found in the old world only in the biscayan and congo languages (vater, mithridates. william von humboldt, on the basque language). strange conformity in the structure of languages on spots so distant, and among three races of men so different,--the white catalonians, the black congos, and the copper-coloured americans!) an ingenious method of indicating beforehand, either by inflexion of the personal pronouns, which form the terminations of the verb, or by an intercalated suffix, the nature and the relation of its object and its subject, and of distinguishing whether the object be animate or inanimate, of the masculine or the feminine gender, simple or in complex number. it is on account of this general analogy of structure,--it is because american languages which have no words in common (for instance, the mexican and the quichua), resemble each other by their organization, and form complete contrasts to the languages of latin europe, that the indians of the missions familiarize themselves more easily with an american idiom than with the spanish. in the forests of the orinoco i have seen the rudest indians speak two or three tongues. savages of different nations often communicate their ideas to each other by an idiom not their own. if the system of the jesuits had been followed, languages, which already occupy a vast extent of country, would have become almost general. in terra firma and on the orinoco, the caribbean and the tamanac alone would now be spoken; and in the south and south-west, the quichua, the guarano, the omagua, and the araucan. by appropriating to themselves these languages, the grammatical forms of which are very regular, and almost as fixed as those of the greek and sanscrit, the missionaries would place themselves in more intimate connection with the natives whom they govern. the numberless difficulties which occur in the system of a mission consisting of indians of ten or a dozen different nations would disappear with the confusion of idioms. those which are little diffused would become dead languages; but the indian, in preserving an american idiom, would retain his individuality--his national character. thus by peaceful means might be effected what the incas began to establish by force of arms. how indeed can we be surprised at the little progress made by the chaymas, the caribbees, the salives, or the otomacs, in the knowledge of the spanish language, when we recollect that one white man, one single missionary, finds himself alone amidst five or six hundred indians? and that it is difficult for him to establish among them a governador, an alcalde, or a fiscal, who may serve him as an interpreter? if, instead of the missionary system, some other means of civilization were substituted, if, instead of keeping the whites at a distance, they could be mingled with the natives recently united in villages, the american idioms would soon be superseded by the languages of europe, and the natives would receive in those languages the great mass of new ideas which are the fruit of civilization. then the introduction of general tongues, such as that of the incas, or the guaranos, without doubt would become useless. but after having lived so long in the missions of south america, after having so closely observed the advantages and the abuses of the system of the missionaries, i may be permitted to doubt whether that system could be easily abandoned, though it is doubtless very capable of being improved, and rendered more conformable with our ideas of civil liberty. to this it may be answered, that the romans* succeeded in rapidly introducing their language with their sovereignty into the country of the gauls, into boetica, and into the province of africa. (* for the reason of this rapid introduction of latin among the gauls, i believe we must look into the character of the natives and the state of their civilization, and not into the structure of their language. the brown-haired celtic nations were certainly different from the race of the light-haired germanic nations; and though the druid caste recalls to our minds one of the institutions of the ganges, this does not demonstrate that the idiom of the celts belongs, like that of the nations of odin, to a branch of the indo-pelasgic languages. from analogy of structure and of roots, the latin ought to have penetrated more easily on the other side of the danube, than into gaul; but an uncultivated state, joined to great moral inflexibility, probably opposed its introduction among the germanic nations.) but the natives of these countries were not savages;--they inhabited towns; they were acquainted with the use of money; and they possessed institutions denoting a tolerably advanced state of cultivation. the allurement of commerce, and a long abode of the roman legions, had promoted intercourse between them and their conquerors. we see, on the contrary, that the introduction of the languages of the mother-countries was met by obstacles almost innumerable, wherever carthaginian, greek, or roman colonies were established on coasts entirely barbarous. in every age, and in every climate, the first impulse of the savage is to shun the civilized man. the language of the chayma indians was less agreeable to my ear than the caribbee, the salive, and other languages of the orinoco. it has fewer sonorous terminations in accented vowels. we are struck with the frequent repetition of the syllables guaz, ez, puec, and pur. these terminations are derived in part from the inflexion of the verb to be, and from certain prepositions, which are added at the ends of words, and which, according to the genius of the american idioms, are incorporated with them. it would be wrong to attribute this harshness of sound to the abode of the chaymas in the mountains. they are strangers to that temperate climate. they have been led thither by the missionaries; and it is well known that, like all the inhabitants of warm regions, they at first dreaded what they called the cold of caripe. i employed myself, with m. bonpland, during our abode at the hospital of the capuchins, in forming a small catalogue of chayma words. i am aware that languages are much more strongly characterised by their structure and grammatical forms than by the analogy of their sounds and of their roots; and that the analogy of sounds is sometimes so disguised in different dialects of the same tongue, as not to be recognizable; for the tribes into which a nation is divided, often designate the same objects by words altogether heterogeneous. hence it follows that we readily fall into mistakes, if, neglecting the study of the inflexions, and consulting only the roots (for instance, in the words which designate the moon, sky, water, and earth), we decide on the absolute difference of two idioms from the mere want of resemblance in sounds. but, while aware of this source of error, travellers would do well to continue to collect such materials as may be within their reach. if they do not make known the internal structure, and general arrangement of the edifice, they may point out some important parts. the three languages now most used in the provinces of cumana and barcelona, are the chayma, the cumanagota, and the caribbee. they have always been regarded in these countries as different idioms, and a dictionary of each has been written for the use of the missions, by fathers tauste, ruiz-blanco, and breton. the vocabulario y arte de la lengua de los indios chaymas has become extremely scarce. the few american grammars, printed for the most part in the seventeenth century, passed into the missions, and have been lost in the forests. the dampness of the air and the voracity of insects* render the preservation of books almost impossible in those regions (* the termites, so well known in spanish america under the name of comegen, or 'devourer,' is one of these destructive insects.): they are destroyed in a short space of time, notwithstanding every precaution that may be employed. i had much difficulty to collect in the missions, and in the convents, those grammars of american languages, which, on my return to europe, i placed in the hands of severin vater, professor and librarian at the university of konigsberg. they furnished him with useful materials for his great work on the idioms of the new world. i omitted, at the time, to transcribe from my journal, and communicate to that learned gentleman, what i had collected in the chayma tongue. since neither father gili, nor the abbe hervas, has mentioned this language, i shall here explain succinctly the result of my researches. on the right bank of the orinoco, south-east of the mission of encaramada, and at the distance of more than a hundred leagues from the chaymas, live the tamanacs (tamanacu), whose language is divided into several dialects. this nation, formerly very powerful, is separated from the mountains of caripe by the orinoco, by the vast steppes of caracas and of cumana; and by a barrier far more difficult to surmount, the nations of caribbean origin. but notwithstanding distance, and the numerous obstacles in the way of intercourse, the language of the chayma indians is a branch of the tamanac tongue. the oldest missionaries of caripe are ignorant of this curious fact, because the capuchins of aragon seldom visit the southern banks of the orinoco, and scarcely know of the existence of the tamanacs. i recognized the analogy between the idiom of this nation, and that of the chayma indians long after my return to europe, in comparing the materials which i had collected with the sketch of a grammar published in italy by an old missionary of the orinoco. without knowing the chaymas, the abbe gili conjectured that the language of the inhabitants of paria must have some relation to the tamanac.* (* vater has also advanced some well-founded conjectures on the connexion between the tamanac and caribbean tongues and those spoken on the north-east coast of south america. i may acquaint the reader, that i have written the words of the american languages according to the spanish orthography, so that the u should be pronounced oo, the ch like ch in english, etc. having during a great number of years spoken no other language than the castilian, i marked down the sounds according to the orthography of that language, and now i am afraid of changing the value of these signs, by substituting others no less imperfect. it is a barbarous practice, to express, like the greater part of the nations of europe, the most simple and distinct sounds by many vowels, or many united consonants, while they might be indicated by letters equally simple. what a chaos is exhibited by the vocabularies written according to english, german, french, or spanish notations! a new essay, which the illustrious author of the travels in egypt, m. volney, is about to publish on the analysis of sounds found in different nations, and on the notation of those sounds according to a uniform system, will lead to great progress in the study of languages.) i will prove this connection by two means which serve to show the analogy of idioms; namely, the grammatical construction, and the identity of words and roots. the following are the personal pronouns of the chaymas, which are at the same time possessive pronouns; u-re, i, me; eu-re, thou, thee; teu-re, he, him. in the tamanac, u-re, i; amare or anja, thou; iteu-ja, he. the radical of the first and of third person is in the chayma u and teu.* (* we must not wonder at those roots which reduce themselves to a single vowel. in a language of the old continent, the structure of which is so artificially complicated, (the biscayan,) the family name ugarte (between the waters) contains the u of ura (water) and arte between. the g is added for the sake of euphony.) the same roots are found in the tamanac. table of chayma and tamanac words compared: column : english. column : chayma. column : tamanac. i : ure : ure. water : tuna : tuna. rain : conopo* : canopo.* (* the same word, conopo, signifies rain and year. the years are counted by the number of winters, or rainy seasons. they say in chayma, as in sanscrit, 'so many rains,' meaning so many years. in the basque language, the word urtea, year, is derived from urten, to bring forth leaves in spring.) to know : poturu : puturo. fire : apoto : uapto (in caribbean uato). the moon, a month : nuna : nuna.* (* in the tamanac and caribbean languages, nono signifies the earth, nuna the moon; as in the chayma. this affinity appears to me very curious; and the indians of the rio caura say, that the moon is 'another earth.' among savage nations, amidst so many confused ideas, we find certain reminiscences well worthy of attention. among the greenlanders nuna signifies the earth, and anoningat the moon.) a tree : je : jeje. a house : ata : aute. to you : euya : auya. to you : toya : iteuya. honey : guane : uane. he has said it : nacaramayre : nacaramai. a physician, a sorcerer : piache : psiache. one : tibin : obin (in jaoi, tewin). two : aco : oco (in caribbean, occo). two : oroa : orua (in caribbean, oroa). flesh : pun : punu. no (negation) : pra : pra. the verb to be, is expressed in chayma by az. on adding to the verb the personal pronoun i (u from u-re), a g is placed, for the sake of euphony, before the u, as in guaz, i am, properly g-u-az. as the first person is known by an u, the second is designated by an m, the third by an i; maz, thou art; muerepuec araquapemaz? why art thou sad? properly what for sad thou art; punpuec topuchemaz, thou art fat in body, properly flesh (pun) for (puec) fat (topuche) thou art (maz). the possessive pronouns precede the substantive; upatay, in my house, properly my house in. all the prepositions and the negation pra are incorporated at the end, as in the tamanac. they say in chayma, ipuec, with him, properly him with; euya, to thee, or thee to; epuec charpe guaz, i am gay with thee, properly thee with gay i am; ucarepra, not as i, properly i as not; quenpotupra quoguaz, i do not know him, properly him knowing not i am; quenepra quoguaz, i have not seen him, properly him seeing not i am. in the tamanac tongue, acurivane means beautiful, and acurivanepra, ugly--not beautiful; outapra, there is no fish, properly fish none; uteripipra, i will not go, properly i to go will not, composed of uteri,* to go, ipiri, to choose, and pra, not. (* in chayma: utechire, i will go also, properly i (u) to go (the radical ute, or, because of the preceding vowel, te) also (chere, or ere, or ire). in utechire we find the tamanac verb to go, uteri, of which ute is also the radical, and ri the termination of the infinitive. in order to show that in chayma chere or ere indicates the adverb also, i shall cite from the fragment of a vocabulary in my possession, u-chere, i also; nacaramayre, he said so also; guarzazere, i carried also; charechere, to carry also. in the tamanac, as in the chayma, chareri signifies to carry.) among the caribbees, whose language also bears some relation to the tamanac, though infinitely less than the chayma, the negation is expressed by an m placed before the verb: amoyenlengati, it is very cold; and mamoyenlengati, it is not very cold. in an analogous manner, the particle mna added to the tamanac verb, not at the end, but by intercalation, gives it a negative sense, as taro, to say, taromnar, not to say. the verb to be, very irregular in all languages, is az or ats in chayma; and uochiri (in composition uac, uatscha) in tamanac. it serves not only to form the passive, but it is added also, as by agglutination, to the radical of attributive verbs, in a number of tenses.* (* the present in the tamanac, jarer-bae-ure, appears to me nothing else then the verb bac, or uac (from uacschiri, to be ), added to the radical to carry, jare (in the infinitive jareri), the result of which is carrying to be i.) these agglutinations remind us of the employment in the sanscrit of the auxiliary verbs as and bhu (asti and bhavati* (* in the branch of the germanic languages we find bhu under the forms bim, bist; as, in the forms vas, vast, vesum (bopp page ).)); the latin, of es and fu, or fus;* (* hence fu-ero; amav-issem; amav-eram; pos-sum (pot-sum).) the biscayan, of izan, ucan, and eguin. there are certain points in which idioms the most dissimilar concur one with another. that which is common in the intellectual organization of man is reflected in the general structure of language; and every idiom, however barbarous it may appear, discloses a regulating principle which has presided at its formation. the plural, in tamanac, is indicated in seven different ways, according to the termination of the substantive, or according as it designates an animate or inanimate object.* (* tamanacu, a tamanac (plur. tamanakemi): pongheme, a spaniard (properly a man clothed); pongamo, spaniards, or men clothed. the plural in cne characterizes inanimate objects: for example, cene, a thing; cenecne, things: jeje, a tree; jejecne, trees.) in chayma the plural is formed as in caribbee, in on; teure, himself; teurecon, themselves; tanorocon, those here; montaonocon, those below, supposing that the interlocutor is speaking of a place where he was himself present; miyonocon, those below, supposing he speaks of a place where he was not present. the chaymas have also the castilian adverbs aqui and alla, shades of difference which can be expressed only by periphrasis, in the idioms of germanic and latin origin. some indians, who were acquainted with spanish, assured us, that zis signified not only the sun, but also the deity. this appeared to me the more extraordinary, as among all other american nations we find distinct words for god and the sun. the carib does not confound tamoussicabo, the ancient of heaven, with veyou, the sun. even the peruvian, though a worshipper of the sun, raises his mind to the idea of a being who regulates the movements of the stars. the sun, in the language of the incas, bears the name of inti,* (* in the quichua, or language of the incas, the sun is inti; love, munay; great, veypul; in sanscrit, the sun, indre: love, manya; great, vipulo. (vater mithridates tome page .) these are the only examples of analogy of sound, that have yet been noticed. the grammatical character of the two languages is totally different.) nearly the same as in sanscrit; while god is called vinay huayna, the eternally young.'* (* vinay, always, or eternal; huayna, in the flower of age.) the arrangement of words in the chayma is similar to that found in all the languages of both continents, which have preserved a certain primitive character. the object is placed before the verb, the verb before the personal pronoun. the object, on which the attention should be principally fixed, precedes all the modifications of that object. the american would say, liberty complete love we, instead of we love complete liberty; thee with happy am i, instead of i am happy with thee. there is something direct, firm, demonstrative, in these turns, the simplicity of which is augmented by the absence of the article. may it be presumed that, with advancing civilization, these nations, left to themselves, would have gradually changed the arrangement of their phrases? we are led to adopt this idea, when we reflect on the changes which the syntax of the romans has undergone in the precise, clear, but somewhat timid languages of latin europe. the chayma, like the tamanac and most of the american languages, is entirely destitute of certain letters, as f, b, and d. no word begins with an l. the same observation has been made on the mexican tongue, though it is overcharged with the syllables tli, tla, and itl, at the end or in the middle of words. the chaymas substitute r for l; a substitution that arises from a defect of pronunciation common in every zone.* (* for example, the substitution of r for l, characterizes the bashmurie dialect of the coptic language.) thus, the caribbees of the orinoco have been transformed into galibi in french guiana by confounding r with l, and softening the c. the tamanac has made choraro and solalo of the spanish word soldado (soldier). the disappearance of the f and b in so many american idioms arises out of that intimate connection between certain sounds, which is manifested in all languages of the same origin. the letters f, v, b, and p, are substituted one for the other; for instance, in the persian, peder, father (pater); burader,* (* whence the german bruder, with the same consonants.) brother (frater); behar, spring (ver); in greek, phorton (forton), a burthen; pous (pous) a foot, (fuss, germ.). in the same manner, with the americans, f and b become p; and d becomes t. the chayma pronounces patre, tios, atani, aracapucha, for padre, dios, adan, and arcabuz (harquebuss). in spite of the relations just pointed out, i do not think that the chayma language can be regarded as a dialect of the tamanac, as the maitano, cuchivero, and crataima undoubtedly are. there are many essential differences; and between the two languages there appears to me to exist merely the same connection as is found in the german, the swedish, and the english. they belong to the same subdivision of the great family of the tamanac, caribbean, and arowak tongues. as there exists no absolute measure of resemblance between idioms, the degrees of parentage can be indicated only by examples taken from known tongues. we consider those as being of the same family, which bear affinity one to the other, as the greek, the german, the persian, and the sanscrit. some philologists have imagined, on comparing languages, that they may all be divided into two classes, of which some, comparatively perfect in their organization, easy and rapid in their movements, indicate an interior development by inflexion; while others, more rude and less susceptible of improvement, present only a crude assemblage of small forms or agglutinated particles, each preserving the physiognomy peculiar to itself; when it is separately employed. this very ingenious view would be deficient in accuracy were it supposed that there exist polysyllabic idioms without any inflexion, or that those which are organically developed as by interior germs, admit no external increase by means of suffixes and affixes;* (* even in the sanscrit several tenses are formed by aggregation; for example, in the first future, the substantive verb to be is added to the radical. in a similar manner we find in the greek mach-eso, if the s be not the effect of inflexion, and in latin pot-ero (bopp pages and ). these are examples of incorporation and agglutination in the grammatical system of languages which are justly cited as models of an interior development by inflexion. in the grammatical system of the american tongues, for example in the tamanac, tarecschi, i will carry, is equally composed of the radical ar (infin. jareri, to carry) and of the verb ecschi (infin. nocschiri, to be). there hardly exists in the american languages a triple mode of aggregation, of which we cannot find a similar and analogous example in some other language that is supposed to develop itself only by inflexion.) an increase which we have already mentioned several times under the name of agglutination or incorporation. many things, which appear to us at present inflexions of a radical, have perhaps been in their origin affixes, of which there have barely remained one or two consonants. in languages, as in everything in nature that is organized, nothing is entirely isolated or unlike. the farther we penetrate into their internal structure, the more do contrasts and decided characters vanish. it may be said that they are like clouds, the outlines of which do not appear well defined, except when viewed at a distance. but though we may not admit one simple and absolute principle in the classification of languages, yet it cannot be decided, that in their present state some manifest a greater tendency to inflexion, others to external aggregation. it is well known, that the languages of the indian, pelasgic, and german branch, belong to the first division; the american idioms, the coptic or ancient egyptian, and to a certain degree, the semitic languages and the biscayan, to the second. the little we have made known of the idiom of the chaymas of caripe, sufficiently proves that constant tendency towards the incorporation or aggregation of certain forms, which it is easy to separate; though from a somewhat refined sentiment of euphony some letters have been dropped and others have been added. those affixes, by lengthening words, indicate the most varied relations of number, time, and motion. when we reflect on the peculiar structure of the american languages, we imagine we discover the source of the opinion generally entertained from the most remote time in the missions, that these languages have an analogy with the hebrew and the biscayan. at the convent of caripe as well as at the orinoco, in peru as well as in mexico, i heard this opinion expressed, particularly by monks who had some vague notions of the semitic languages. did motives supposed to be favourable to religion, give rise to this extraordinary theory? in the north of america, among the choctaws and the chickasaws, travellers somewhat credulous have heard the strains of the hallelujah* of the hebrews (* l'escarbot, charlevoix, and even adair (hist. of the american indians ).); as, according to the pundits, the three sacred words of the mysteries of the eleusis* (konx om pax) resound still in the indies. (* asiat. res. volume , ouvaroff on the eleusinian mysteries .) i do not mean to suggest, that the nations of latin europe may have called whatever has a foreign physiognomy hebrew or biscayan, as for a long time all those monuments were called egyptian, which were not in the grecian or roman style. i am rather disposed to think that the grammatical system of the american idioms has confirmed the missionaries of the sixteenth century in their ideas respecting the asiatic origin of the nations of the new world. the tedious compilation of father garcia, tratado del origen de los indios,* (* treatise on the origin of the indians.) is a proof of this. the position of the possessive and personal pronouns at the end of the noun and the verb, as well as the numerous tenses of the latter, characterize the hebrew and the other semitic languages. some of the missionaries were struck at finding the same peculiarities in the american tongues: they did not reflect, that the analogy of a few scattered features does not prove languages to belong to the same stock. it appears less astonishing, that men, who are well acquainted with only two languages extremely heterogeneous, the castilian and the biscayan, should have found in the latter a family resemblance to the american languages. the composition of words, the facility with which the partial elements are detected, the forms of the verbs, and their different modifications, may have caused and kept up this illusion. but we repeat, an equal tendency towards aggregation or incorporation does not constitute an identity of origin. the following are examples of the relations between the american and biscayan languages; idioms totally different in their roots. in chayma, quenpotupra quoguaz, i do not know, properly, knowing not i am. in tamanac, jarer-uac-ure, bearing am i,--i bear; anarepra aichi, he will not bear, properly, bearing not will he; patcurbe, good; patcutari, to make himself good; tamanacu, a tamanac; tamanacutari, to make himself a tainanac; pongheme, a spaniard; ponghemtari, to spaniardize himself; tenecchi, i will see; teneicre, i will see again; teecha, i go; tecshare, i return; maypur butke, a little maypure indian; aicabutke, a little woman; maypuritaje, an ugly maypure indian; aicataje, an ugly woman.* (* the diminutive of woman (aica) or of maypure indian is formed by adding butke, which is the termination of cujuputke, little: taje answers to the accio of the italians.) in biscayan: maitetutendot, i love him, properly, i loving have him; beguia, the eye, and beguitsa, to see; aitagana, towards the father: by adding tu, we form the verb aitaganatu, to go towards the father; ume-tasuna, soft and infantile ingenuity; umequeria, disagreeable childishness. i may add to these examples some descriptive compounds, which call to mind the infancy of nations, and strike us equally in the american and biscayan languages, by a certain ingenuousness of expression. in tamanac, the wasp (uane-imu), father (im-de) of honey (uane);* (* it may not be unnecessary here to acquaint the reader that honey is produced by an insect of south america, belonging to, or nearly allied, to the wasp genus. this honey, however, possesses noxious qualities which are by some naturalists attributed to the plant paulinia australis, the juices of which are collected by the insect.) the toes, ptarimucuru, properly, the sons of the foot; the fingers, amgnamucuru, the sons of the hand; mushrooms, jeje-panari, properly, the ears (panari) of a tree (jeje); the veins of the hand, amgna-mitti, properly, the ramified roots; leaves, prutpe-jareri, properly, the hair at the top of the tree; puirene-veju, properly, the sun (veju), straight or perpendicular; lightning, kinemeru-uaptori, properly, the fire (uapto) of the thunder, or of the storm. (i recognise in kinemeru, thunder or storm, the root kineme black.) in biscayan, becoquia, the forehead, what belongs (co and quia) to the eye (beguia); odotsa, the noise (otsa) of the cloud (odeia), or thunder; arribicia, an echo, properly, the animated stone, from arria, stone, and bicia, life. the chayma and tamanac verbs have an enormous complication of tenses: two presents, four preterites, three futures. this multiplicity characterises the rudest american languages. astarloa reckons, in like manner, in the grammatical system of the biscayan, two hundred and six forms of the verb. those languages, the principal tendency of which is inflexion, are to the common observer less interesting than those which seem formed by aggregation. in the first, the elements of which words are composed, and which are generally reduced to a few letters, are no longer recognisable: these elements, when isolated, exhibit no meaning; the whole is assimilated and mingled together. the american languages, on the contrary, are like complicated machines, the wheels of which are exposed to view. the mechanism of their construction is visible. we seem to be present at their formation, and we should pronounce them to be of very recent origin, did we not recollect that the human mind steadily follows an impulse once given; that nations enlarge, improve, and repair the grammatical edifice of their languages, according to a plan already determined; finally, that there are countries, whose languages, institutions, and arts, have remained unchanged, we might almost say stereotyped, during the lapse of ages. the highest degree of intellectual development has been hitherto found among the nations of the indian and pelasgic branch. the languages formed principally by aggregation seem themselves to oppose obstacles to the improvement of the mind. they are devoid of that rapid movement, that interior life, to which the inflexion of the root is favourable, and which impart such charms to works of imagination. let us not, however, forget, that a people celebrated in remote antiquity, a people from whom the greeks themselves borrowed knowledge, had perhaps a language, the construction of which recalls involuntarily that of the languages of america. what a structure of little monosyllabic and disyllabic forms is added to the verb and to the substantive, in the coptic language! the semi-barbarous chayma and tamanac have tolerably short abstract words to express grandeur, envy, and lightness, cheictivate, uoite, and uonde; but in coptic, the word malice,* metrepherpetou, is composed of five elements, easy to be distinguished. (* see, on the incontestable identity of the ancient egyptian and coptic, and on the particular system of synthesis of the latter language, the ingenious reflexions of m. silvestre de sacy, in the notice des recherches de m. etienne quatremere sur la litterature de l'epypte. ) this compound signifies the quality (met) of a subject (reph), which makes (er) the thing which is (pet), evil (ou). nevertheless the coptic language has had its literature, like the chinese, the roots of which, far from being aggregated, scarcely approach each other without immediate contact. we must admit that nations once roused from their lethargy, and tending towards civilization, find in the most uncouth languages the secret of expressing with clearness the conceptions of the mind, and of painting the emotions of the soul. don juan de la rea, a highly estimable man, who perished in the sanguinary revolutions of quito, imitated with graceful simplicity some idylls of theocritus in the language of the incas; and i have been assured, that, excepting treatises on science and philosophy, there is scarcely any work of modern literature that might not be translated into the peruvian. the intimate connection established between the natives of the new world and the spaniards since the conquest, have introduced a certain number of american words into the castilian language. some of these words express things not unknown before the discovery of the new world, and scarcely recall to our minds at present their barbarous origin.* (* for example savannah, and cannibal.) almost all belong to the language of the great antilles, formerly termed the language of haiti, of quizqueja, or of itis.* (* the word itis, for haiti or st. domingo (hispaniola), is found in the itinerarium of bishop geraldini (rome .)--"quum colonus itim insulam cerneret.") i shall confine myself to citing the words maiz, tabaco, canoa, batata, cacique, balsa, conuco, etc. when the spaniards, after the year , began to visit the mainland, they already had words* to designate the vegetable productions most useful to man, and common both to the islands and to the coasts of cumana and paria. (* the following are haitian words, in their real form, which have passed into the castilian language since the end of the th century. many of them are not uninteresting to descriptive botany. ahi (capsicum baccatum), batata (convolvus batatas), bihao (heliconia bihai), caimito (chrysophyllum caimito), cahoba (swietenia mahagoni), jucca and casabi (jatropba manihot); the word casabi or cassava is employed only for the bread made with the roots of the jatropha (the name of the plant jucca was also heard by americo vespucci on the coast of paria); age or ajes (dioscorea alata), copei (clusia alba), guayacan (guaiacum officinale), guajaba (psidium pyriferum), guanavano (anona muricata), mani (arachis hypogaea), guama (inga), henequen (was supposed from the erroneous accounts of the first travellers to be an herb with which the haitians used to cut metals; it means now every kind of strong thread), hicaco (chrysobalanus icaco), maghei (agave americana), mahiz or maiz (zea, maize), mamei (mammea americana), mangle (rhizophora), pitahaja (cactus pitahaja), ceiba (bombax), tuna (cactus tuna), hicotea (a tortoise), iguana (lacerta iguana), manatee (trichecus manati), nigua (pulex penetrans), hamaca (a hammock), balsa (a raft; however balsa is an old castilian word signifying a pool of water), barbacoa (a small bed of light wood, or reeds), canei or buhio (a hut), canoa (a canoe), cocujo (elater noctilucus, the fire-fly), chicha (fermented liquor), macana (a large stick or club, made with the petioles of a palm-tree), tabaco (not the herb, but the pipe through which it is smoked), cacique (a chief). other american words, now as much in use among the creoles, as the arabic words naturalized in the spanish, do not belong to the haitian tongue; for example, caiman, piragua, papaja (carica), aguacate (persea), tarabita, paramo. abbe gili thinks with some probability, that they are derived from the tongue of some people who inhabited the temperate climate between coro, the mountains of merida, and the tableland of bogota. (saggio volume page .) how many celtic and german words would not julius caesar and tacitus have handed down to us, had the productions of the northern countries visited by the romans differed as much from the italian and roman, as those of equinoctial america!) not satisfied with retaining these words borrowed from the haitians, they helped also to spread them all over america (at a period when the language of haiti was already a dead language), and to diffuse them among nations who were ignorant even of the existence of the west india islands. some words, which are in daily use in the spanish colonies, are attributed erroneously to the haitians. banana is from the chaconese, the mbaja language; arepa (bread of manioc, or of the jatropha manihot) and guayuco (an apron, perizoma) are caribbee: curiara (a very long boat) is tamanac: chinchorro (a hammock), and tutuma (the fruit of the crescentia cujete, or a vessel to contain a liquid), are chayma words. i have dwelt thus long on considerations respecting the american tongues, because i am desirous of directing attention to the deep interest attached to this kind of research. this interest is analogous to that inspired by the monuments of semi-barbarous nations, which are examined not because they deserve to be ranked among works of art, but because the study of them throws light on the history of our species, and the progressive development of our faculties. it now remains for me to speak of the other indian nations inhabiting the provinces of cumana and barcelona. these i shall only succinctly enumerate. . the pariagotos or parias. it is thought that the terminations in goto, as pariagoto, purugoto, avarigoto, acherigoto, cumanagoto, arinagoto, kirikirisgoto,* (* the kirikirisgotos (or kirikiripas) are of dutch guiana. it is very remarkable, that among the small brazilian tribes who do not speak the language of the tupis, the kiriris, notwithstanding the enormous distance of leagues, have several tamanac words.) imply a caribbean origin.* (* in the tamanac tongue, which is of the same branch as the caribbean, we find also the termination goto, as in anekiamgoto an animal. often an analogy in the termination of names, far from showing an identity of race, only indicates that the names of the nations are borrowed from one language.) all these tribes, excepting the purugotos of the rio caura, formerly occupied the country which has been so long under the dominion of the caribbees; namely, the coasts of berbice and of essequibo, the peninsula of paria, the plains of piritu and parima. by this last name the little-known country, between the sources of the cujuni, the caroni, and the mao, is designated in the missions. the paria indians are mingled in part with the chaymas of cumana; others have been settled by the capuchins of aragon in the missions of caroni; for instance, at cupapuy and alta-gracia, where they still speak their own language, apparently a dialect between the tamanac and the caribbee. but it may be asked, is the name parias or pariagotos, a name merely geographical? did the spaniards, who frequented these coasts from their first establishment in the island of cubagua and in macarapana, give the name of the promontory of paria* to the tribe by which it was inhabited? (* paria, uraparia, even huriaparia and payra, are the ancient names of the country, written as the first navigators thought they heard them pronounced. it appears to me by no means probable, that the promontory of paria should derive its name from that of a cacique uriapari, celebrated for the manner in which he resisted diego ordaz in , thirty-two years after columbus had heard the name of paria from the mouths of the natives themselves. the orinoco at its mouth had also the name of uriapari, yuyapari, or iyupari. in all these denominations of a great river, of a shore, and of a rainy country, i think i recognise the radical par, signifying water, not only in the languages of these countries, but also in those of nations very distant from one another on the eastern and western coasts of america. the sea, or great water, is in the caribbean, maypure, and brazilian languages, parana: in the tamanac, parava. in upper guiana also the orinoco is called parava. in the peruvian, or quichua, i find rain, para; to rain, parani. besides, there is a lake in peru that has been very anciently called paria. (garcia, origen de los indios, page .) i have entered into these minute details concerning the word paria, because it has recently been supposed that some connection might be traced between this word and the country of the hindoo caste called the parias.) this we will not positively affirm; for the caribbees themselves give the name of caribana to a country which they occupied, and which extended from the rio sinu to the gulf of darien. this is a striking example of identity of name between an american nation and the territory it possessed. we may conceive, that in a state of society, where residence is not long fixed, such instances must be very rare. . the guaraons or gu-ara-una, almost all free and independent, are dispersed in the delta of the orinoco, with the variously ramified channels of which they alone are well acquainted. the caribbees call the guaraons u-ara-u. they owe their independence to the nature of their country; for the missionaries, in spite of their zeal, have not been tempted to follow them to the tree-tops. the guaraons, in order to raise their abodes above the surface of the waters at the period of the great inundations, support them on the hewn trunks of the mangrove-tree and of the mauritia palm-tree.* (* their manners have been the same from time immemorial. cardinal bembo described them at the beginning of the th century, "quibusdam in locis propter paludes incolae domus in arboribus aedificant." (hist. venet. .) sir walter raleigh, in , speaks of the guaraons under the names of araottes, trivitivas, and warawites. these were perhaps the names of some tribes, into which the great guaraonese nation was divided. (barrere essai sur l'hist. naturelle de la france equinoctiale.)) they make bread of the medullary flour of this palm-tree, which is the sago of america. the flour bears the name of yuruma: i have eaten it at the town of st. thomas, in guiana, and it was very agreeable to the taste, resembling rather the cassava-bread than the sago of india.* (* m. kunth has combined together three genera of the palms, calamus, sigus, and mauritia, in a new section, the calameae.) the indians assured me that the trunks of the mauritia, the tree of life so much vaunted by father gumilla, do not yield meal in any abundance, unless the palm-tree is cut down just before the flowers appear. thus too the maguey,* (* agave americana, the aloe of our gardens.) cultivated in new spain, furnishes a saccharine liquor, the wine (pulque) of the mexicans, only at the period when the plant shoots forth its long stem. by interrupting the blossoming, nature is obliged to carry elsewhere the saccharine or amylaceous matter, which would accumulate in the flowers of the maguey and in the fruit of the mauritia. some families of guaraons, associated with the chaymas, live far from their native land, in the missions of the plains or llanos of cumana; for instance, at santa rosa de ocopi. five or six hundred of them voluntarily quitted their marshes, a few years ago, and formed, on the northern and southern banks of the orinoco, twenty-five leagues distant from cape barima, two considerable villages, under the names of zacupana and imataca. when i made my journey in caripe, these indians were still without missionaries, and lived in complete independence. their excellent qualities as boatmen, their perfect knowledge of the mouths of the orinoco, and of the labyrinth of branches communicating with each other, give the guaraons a certain political importance. they favour that clandestine commerce of which the island of trinidad is the centre. the guaraons run with extreme address on muddy lands, where the european, the negro, or other indians except themselves, would not dare to walk; and it is, therefore, commonly believed, that they are of lighter weight than the rest of the natives. this is also the opinion that is held in asia of the burat tartars. the few guaraons whom i saw were of middle size, squat, and very muscular. the lightness with which they walk in places newly dried, without sinking in, when even they have no planks tied to their feet, seemed to me the effect of long habit. though i sailed a considerable time on the orinoco, i never went so low as its mouth. future travellers, who may visit those marshy regions, will rectify what i have advanced. . the guaiqueries or guaikeri, are the most able and most intrepid fishermen of these countries. these people alone are well acquainted with the bank abounding with fish, which surrounds the islands of coche, margareta, sola, and testigos; a bank of more than four hundred square leagues, extending east and west from maniquarez to the boca del draco. the guaiqueries inhabit the island of margareta, the peninsula of araya, and that suburb of cumana which bears their name. their language is believed to be a dialect of that of the guaraons. this would connect them with the great family of the caribbee nations; and the missionary gili is of opinion that the language of the guaiqueries is one of the numerous branches of the caribbean tongue.* (* if the name of the port pam-patar, in the island of margareta, be guaiquerean, as we have no reason to doubt, it exhibits a feature of analogy with the cumanagoto tongue, which approaches the caribbean and tamanac. in terra firma, in the piritu missions, we find the village of cayguapatar, which signifies house of caygua.) these affinities are interesting, because they lead us to perceive an ancient connection between nations dispersed over a vast extent of country, from the mouth of the rio caura and the sources of the erevato, in parima, to french guiana, and the coasts of paria.* (* are the guaiqueries, or o-aikeries, now settled on the borders of the erevato, and formerly between the rio caura and the cuchivero near the little town of alta gracia, of a different origin from the guaikeries of cumana? i know also, in the interior of the country, in the missions of the piritus, near the village of san juan evangelista del guarive, a ravine very anciently called guayquiricuar. these resemblances seem to prove migrations from the south-west towards the coast. the termination cuar, found so often in cumanagoto and caribbean names, means a ravine, as in guaymacuar (ravine of lizards), pirichucuar (a ravine overshaded by pirichu or piritu palm-trees), chiguatacuar (a ravine of land-shells). raleigh describes the guaiqueries under the name of ouikeries. he calls the chaymas, saimas, changing (according to the caribbean pronunciation) the ch into s.) . the quaquas, whom the tamanacs call mapoje, are a tribe formerly very warlike and allied to the caribbees. it is a curious phenomenon to find the quaquas mingled with the chaymas in the missions of cumana, for their language, as well as the atura, of the cataracts of the orinoco, is a dialect of the salive tongue; and their original abode was on the banks of the assiveru, which the spaniards call cuchivero. they have extended their migrations one hundred leagues to the north-east. i have often heard them mentioned on the orinoco, above the mouth of the meta; and, what is very remarkable, it is asserted* that missionary jesuits have found quaquas as far distant as the cordilleras of popayan. (* vater tome part page . the name of quaqua is found on the coast of guinea. the europeans apply it to a horde of negroes to the east of cape lahou.) raleigh enumerates, among the natives of the island of trinidad, the salives, a people remarkable for their mild manners; they came from the orinoco, and settled south of the quaquas. perhaps these two nations, which speak almost the same language, travelled together towards the coasts. . the cumanagotos, or, according to the pronunciation of the indians, cumanacoto, are now settled westward of cumana, in the missions of piritu, where they live by cultivating the ground. they number more than twenty-six thousand. their language, like that of the palencas, or palenques, and guarivas, is between the tamanac and the caribbee, but nearer to the former. these are indeed idioms of the same family; but if we are to consider them as simple dialects, the latin must be also called a dialect of the greek, and the swedish a dialect of the german. in considering the affinity of languages one with another, it must not be forgotten that these affinities may be very differently graduated; and that it would be a source of confusion not to distinguish between simple dialects and languages of the same family. the cumanagotos, the tamanacs, the chaymas, the guaraons, and the caribbees, do not understand each other, in spite of the frequent analogy of words and of grammatical structure exhibited in their respective idioms. the cumanagotos inhabited, at the beginning of the sixteenth century, the mountains of the brigantine and of parabolata. i am unable to determine whether the piritus, cocheymas, chacopatas, tomuzas, and topocuares, now confounded in the same villages with the cumanagotos, and speaking their language, were originally tribes of the same nation. the piritus take their name from the ravine pirichucuar, where the small thorny palm-tree,* called piritu, grows in abundance (* caudice gracili aculeato, foliis pinnatis. possibly of the genus aiphanes of willdenouw.); the wood of this tree, which is excessively hard, and little combustible, serves to make pipes. on this spot the village of la concepcion de piritu was founded in ; it is the chief settlement of the cumanagoto missions, known by the name of the misiones de piritu. . the caribbees (carives). this name, which was given them by the first navigators, is retained throughout all spanish america. the french and the germans have transformed it, i know not why, into caraibes. the people call themselves carina, calina, and callinago. i visited some caribbean missions in the llanos,* (* i shall in future use the word llanos (loca plana, suppressing the p), without adding the equivalent words pampas, savannahs, meadows, steppes, or plains. the country between the mountains of the coast and the left bank of the orinoco, constitutes the llanos of cumana, barcelona, and caracas.) on returning from my journey to the orinoco; and i shall merely mention that the galibes (caribi of cayenne), the tuapocas, and the cunaguaras, who originally inhabited the plains between the mountains of caripe (caribe) and the village of maturin, the jaoi of the island of trinidad and of the province of cumana, and perhaps also the guarivas, allies of the palencas, are all tribes of the great caribbee nation. with respect to the other nations whose affinities of language with the tamanac and caribbee have been mentioned, they are not necessarily to be considered as of the same race. in asia, the nations of mongol origin differ totally in their physical organisation from those of tartar origin. such has been, however, the intermixture of these nations, that, according to the able researches of klaproth, the tartar languages (branches of the ancient oigour) are spoken at present by hordes incontestably of mongol race. neither the analogy nor the diversity of language suffice to solve the great problem of the filiation of nations; they merely serve to point out probabilities. the caribbees, properly speaking, those who inhabit the missions of the cari, in the llanos of cumana, the banks of the caura, and the plains to the north-east of the sources of the orinoco, are distinguished by their almost gigantic size from all the other nations i have seen in the new continent. must it on this account be admitted, that the caribbees are an entirely distinct race? and that the guaraons and the tamanacs, whose languages have an affinity with the caribbee, have no bond of relationship with them? i think not. among the nations of the same family, one branch may acquire an extraordinary development of organization. the mountaineers of the tyrol and salzburgh are taller than the other germanic races; the samoiedes of the altai are not so little and squat as those of the sea-coast. in like manner it would be difficult to deny that the galibis are really caribbees; and yet, notwithstanding the identity of languages, how striking is the difference in their stature and physical constitution! before cortez entered the capital of montezuma in , the attention of europe was fixed on the regions we have just traversed. in depicting the manners of the inhabitants of paria and cumana, it was thought that the manners of all the inhabitants of the new continent were described. this remark cannot escape those who read the historians of the conquest, especially the letters of peter martyr of anghiera, written at the court of ferdinand the catholic. these letters are full of ingenious observations upon christopher columbus, leo x, and luther, and are stamped by noble enthusiasm for the great discoveries of an age so rich in extraordinary events. without entering into any detail on the manners of the nations which have been so long confounded one with another, under the vague denomination of cumanians (cumaneses), it appears to me important to clear up a fact which i have often heard discussed in spanish america. the pariagotos of the present time are of a brown red colour, as are the caribbees, the chaymas, and almost all the nations of the new world. why do the historians of the sixteenth century affirm that the first navigators saw white men with fair hair at the promontory of paria? were they of the same race as those indians of a less tawny hue, whom m. bonpland and myself saw at esmeralda, near the sources of the orinoco? but these indians had hair as black as the otomacs and other tribes, whose complexion is the darkest. were they albinos, such as have been found heretofore in the isthmus of panama? but examples of that degeneration are very rare in the copper-coloured race; and anghiera, as well as gomara, speaks of the inhabitants of paria in general, and not of a few individuals. both describe them as if they were people of germanic origin,* (* "aethiopes nigri, crispi lanati; pariae incolae albi, capillis oblongis protensis flavis."--pet. martyr ocean., dec. lib. (edition ). "utriusque sexus indigenae albi veluti nostrates, praeter eos qui sub sole versantur." (the natives of both sexes are as white as our people [spaniards], except those who are exposed to the sun.)--ibid. gomara, speaking of the natives seen by columbus at the mouth of the river of cumana, says: "las donzellas eran amorosas, desnudas y blancas (las de la casa); los indios que van al campo estan negros del sol." (the young women are engaging in their manners: they wear no clothing, and those who live in the houses are white. the indians who are much in the open country are black, from the effect of the sun.)--hist. de los indios, cap. . "los indios de paria son blancos y rubios."--(the indians of paria are white and red.) garcia, origen de los indios , lib. cap. .) they call them 'whites with light hair;' they even add, that they wore garments like those of the turks.* (* "they wear round their head a striped cotton handkerchief"--ferd. columb. cap. . (churchill volume .) was this kind of head-dress taken for a turban? (garcia, origen de los ind., page ). i am surprised that people of these regions should have worn a head-dress; but, what is more curious still, pinzon, in a voyage which he made alone to the coast of paria, the particulars of which have been transmitted to us by peter martyr of anghiera, professes to have seen natives who were clothed: "incolas omnes genu tenus mares, foeminas surarum tenus, gossampinis vestibus amictos simplicibus repererunt; sed viros more turcorum insuto minutim gossypio ad belli usum duplicibus." (the natives were clothed in thin cotton garments; the men's reaching to the knee, and the women's to the calf of the leg. their war-dress was thicker, and closely stitched with cotton after the turkish manner.)--pet. martyr, dec. lib. . who were these people described as being comparatively civilized, and clothed with tunics (like those who lived an the summit of the andes), and seen on a coast, where before and since the time of pinzon, only naked men have ever been seen?) gomara and anghiera wrote from such oral information as they had been able to collect. these marvels disappear, if we examine the recital which ferdinand columbus drew up from his father's papers. there we find simply, that "the admiral was surprised to see the inhabitants of paria, and those of the island of trinidad, better made, more civilized (de buena conversacion), and whiter than the natives whom he had previously seen."* (* churchill's collection volume , herrera pages , , . munoz, hist. del nuevo mundo volume , "el color era baxo como es regular en los indios, pero mas clara que en las islas reconocidas." (their colour was dark, as is usual among the indians; but lighter than that of the people of the islands previously known.) the missionaries are accustomed to call those indians who are less black, less tawny, whitish, and even almost white.--gumilla, hist. de l'orenoque volume chapter paragraph . such incorrect expressions may mislead those who are not accustomed to the exaggerations in which travellers often indulge.) this certainly did not mean that the pariagotos are white. the lighter colour of the skin of the natives and the great coolness of the mornings on the coast of paria, seemed to confirm the fantastic hypothesis which that great man had framed, respecting the irregularity of the curvature of the earth, and the height of the plains in this region, which he regarded as the effect of an extraordinary swelling of the globe in the direction of the parallels of latitude. amerigo vespucci (in his pretended first voyage, apparently written from the narratives of other navigators) compares the natives to the tartar nations,* (* vultu non multum speciosi sunt, quoniam latas facies tartariis adsimilatas habent. (their countenances are not handsome, their cheek-bones being broad like those of the tartars.)--americi vesputii navigatio prima, in gryn's orbis novus .) not in regard to their colour, but on account of the breadth of their faces, and the general expression of their physiognomy. but if it be certain, that at the end of the fifteenth century there were on the coast of cumana a few men with white skins, as there are in our days, it must not thence be concluded, that the natives of the new world exhibit everywhere a similar organization of the dermoidal system. it is not less inaccurate to say, that they are all copper-coloured, than to affirm that they would not have a tawny hue, if they were not exposed to the heat of the sun, or tanned by the action of the air. the natives may be divided into two very unequal portions with respect to numbers; to the first belong the esquimaux of greenland, of labrador, and the northern coast of hudson's bay, the inhabitants of behring's straits, of the peninsula of alaska, and of prince william's sound. the eastern and western branches* of this polar race (* vater, in mithridates volume . egede, krantz, hearne, mackenzie, portlock, chwostoff, davidoff, resanoff, merk, and billing, have described the great family of these tschougaz-esquimaux.), the esquimaux and the tschougases, though at the vast distance of eight hundred leagues apart, are united by the most intimate analogy of languages. this analogy extends even to the inhabitants of the north-east of asia; for the idiom of the tschouktsches* at the mouth of the anadir (* i mean here only the tschouktsches who have fixed dwelling-places, for the wandering tschouktsches approach very near the koriaks.), has the same roots as the language of the esquimaux who inhabit the coast of america opposite to europe. the tschouktsches are the esquimaux of asia. like the malays, that hyperborean race reside only on the sea-coasts. they are almost all smaller in stature than the other americans, and are quick, lively, and talkative. their hair is almost straight, and black; but their skin (and this is very characteristic of the race, which i shall designate under the name of tschougaz-esquimaux) is originally whitish. it is certain that the children of the greenlanders are born white; some retain that whiteness; and often in the brownest (the most tanned) the redness of the blood is seen to appear on their cheeks.* (* krantz, hist. of greenland tome . greenland does not seem to have been inhabited in the eleventh century; at least the esquimaux appeared only in the fourteenth, coming from the west.) the second portion of the natives of america includes all those nations which are not tschougaz-esquimaux, beginning from cook's river to the straits of magellan, from the ugaljachmouzes and the kinaese of mount st. elias, to the puelches and tehuelhets of the southern hemisphere. the men who belong to this second branch, are taller, stronger, more warlike, and more taciturn than the others. they present also very remarkable differences in the colour of their skin. in mexico, peru, new grenada, quito, on the banks of the orinoco and of the river amazon, in every part of south america which i have explored, in the plains as well as on the coldest table-lands, the indian children of two or three months old have the same bronze tint as is observed in adults. the idea that the natives may be whites tanned by the air and the sun, could never have occurred to a spanish inhabitant of quito, or of the banks of the orinoco. in the north-east of america, on the contrary, we meet with tribes among whom the children are white, and at the age of virility they acquire the bronze colour of the natives of mexico and peru. michikinakoua, chief of the miamis, had his arms, and those parts of his body not exposed to the sun, almost white. this difference of hue between the parts covered and not covered is never observed among the natives of peru and mexico, even in families who live much at their ease, and remain almost constantly within doors. to the west of the miamis, on the coast opposite to asia, among the kolouches and tchinkitans* of norfolk sound (* between and degrees of latitude. these white nations have been visited successively by portlock, marchand, baranoff, and davidoff. the tchinkitans, or schinkit, are the inhabitants of the island of sitka. vater mithridates volume page . marchand voyages volume .), grown-up girls, when they have gashed their skin, display the white hue of europeans. this whiteness is found also, according to some accounts, among the mountaineers of chile.* (* molina, saggio sull' istoria nat. del chile edition page . may we believe the existence of those blue eyes of the boroas of chile and guayanas of uruguay; represented to us as nations of the race of odin? azara voyage tome .) these facts are very remarkable, and contrary to the opinion so generally spread, of the extreme conformity of organization among the natives of america. if we divide them into esquimaux and non-esquimaux, we readily admit that this classification is not more philosophical than that of the ancients, who saw in the whole of the habitable world only celts and scythians, greeks, and barbarians. when, however, our purpose is to group numerous nations, we gain something by proceeding in the mode of exclusion. all we have sought to establish here is, that, in separating the whole race of tschougaz-esquimaux, there remain still, among the coppery-brown americans, other races, the children of which are born white, without our being able to prove, by going back as far as the history of the conquest, that they have been mingled with european blood. this fact deserves to be cleared up by travellers who may possess a knowledge of physiology, and may have opportunities of examining the brown children of the mexicans at the age of two years, as well as the white children of the miamis, and those hordes* on the orinoco (* these whitish tribes are the guaycas, the ojos, and the maquiritares.), who, living in the most sultry regions, retain during their whole life, and in the fulness of their strength, the whitish skin of the mestizoes. in man, the deviations from the common type of the whole race are apparent in the stature, the physiognomy, or the form of the body, rather than on the colour of the skin.* (* the circumpolar nations of the two continents are small and squat, though of races entirely different.) it is not so with animals, where varieties are found more in colour than in form. the hair of the mammiferous class of animals, the feathers of birds, and even the scales of fishes, change their hue, according to the lengthened influence of light and darkness, and the intensity of heat and cold. in man, the colouring matter seems to be deposited in the epidermis by the roots or the bulbs of the hair:* (* adverting to the interesting researches of m. gaultier, on the organisation of the human skin, john hunter observes, that in several animals the colorating of the hair is independent of that of the skin.) and all sound observations prove, that the skin varies in colour from the action of external stimuli on individuals, and not hereditarily in the whole race. the esquimaux of greenland and the laplanders are tanned by the influence of the air; but their children are born white. we will not decide on the changes which nature may have produced in a space of time exceeding all historical tradition. reason stops short in these matters, when no longer under the guidance of experience and analogy. all white-skinned nations begin their cosmogony by white men; they allege that the negroes and all tawny people have been blackened or embrowned by the excessive heat of the sun. this theory, adopted by the greeks,* (* strabo, liv. .) though it did not pass without contradiction,* (* onesicritus, apud strabonem, lib. . alexander's expedition appears to have contributed greatly to fix the attention of the greeks on the great question of the influence of climates. they had learned from the accounts of travellers, that in hindostan the nations of the south were of darker colour than those of the north, near the mountains: and they supposed that they were both of the same race.) has been propagated even to our own times. buffon has repeated in prose what theodectes had expressed in verse two thousand years before: "that nations wear the livery of the climate in which they live." if history had been written by black nations, they would have maintained what even europeans have recently advanced,* that man was originally black, or of a very tawny colour (* see the work of mr. prichard, abounding with curious research. "researches into the physical history of man, ," page .); and that mankind have become white in some races, from the effect of civilization and progressive debilitation, as animals, in a state of domestication, pass from dark to lighter colours. in plants and in animals, accidental varieties, formed under our own eyes, have become fixed, and have been propagated;* (* for example, the sheep with very short legs, called ancon sheep in connecticut, and examined by sir everard home. this variety dates only from the year .) but nothing proves, that in the present state of human organization, the different races of black, yellow, copper-coloured, and white men, when they remain unmixed, deviate considerably from their primitive type, by the influence of climate, of food, and other external agents. these opinions are founded on the authority of ulloa.* (* "the indians [americans] are of a copper-colour, which by the action of the sun and the air grows darker. i must remark, that neither heat nor cold produces any sensible change in the colour, so that the indians of the cordilleras of peru are easily confounded with those of the hottest plains; and those who live under the line cannot be distinguished, by their colour, from those who inhabit the fortieth degree of north and south latitude."--noticias americanas. no ancient author has so clearly stated the two forms of reasoning, by which we still explain in our days the differences of colour and features among neighbouring nations, as tacitus. he makes a just distinction between the influence of climate, and hereditary dispositions; and, like a philosopher persuaded of our profound ignorance of the origin of things, he leaves the question undecided. "habitus corporum varii; atque ex eo argumenta, seu durante originis vi, seu procurrentibus in diversa terris, positio coeli corporibus habitum dedit."--agricola, cap .) that learned writer saw the indians of chile, of the andes of peru, of the burning coasts of panama, and those of louisiana, situated in the northern temperate zone. he had the good fortune to live at a period when theories were less numerous; and, like me, he was struck by seeing the natives equally bronzed under the line, in the cold climate of the cordilleras, and in the plains. where differences of colour are observed, they depend on the race. we shall soon find on the burning banks of the orinoco indians with a whitish skin. durans originis vis est. chapter . . second abode at cumana. earthquakes. extraordinary meteors. we remained a month longer at cumana, employing ourselves in the necessary preparations for our proposed visit to the orinoco and the rio negro. we had to choose such instruments as could be most easily transported in narrow boats; and to engage guides for an inland journey of ten months, across a country without communication with the coasts. the astronomical determination of places being the most important object of this undertaking, i felt desirous not to miss the observation of an eclipse of the sun, which was to be visible at the end of october: and in consequence i preferred remaining till that period at cumana, where the sky is generally clear and serene. it was now too late to reach the banks of the orinoco before october; and the high valleys of caracas promised less favourable opportunities, on account of the vapours which accumulate round the neighbouring mountains. i was, however, near being compelled by a deplorable occurrence, to renounce, or at least to delay for a long time, my journey to the orinoco. on the th of october, the day before the eclipse, we went as usual, to take the air on the shore of the gulf, and to observe the instant of high water, which in those parts is only twelve or thirteen inches. it was eight in the evening, and the breeze was not yet stirring. the sky was cloudy; and during a dead calm it was excessively hot. we crossed the beach which separates the suburb of the guayqueria indians from the embarcadero. i heard some one walking behind us, and on turning, i saw a tall man of the colour of the zambos, naked to the waist. he held almost over my head a macana, which is a great stick of palm-tree wood, enlarged to the end like a club. i avoided the stroke by leaping towards the left; but m. bonpland, who walked on my right, was less fortunate. he did not see the zambo so soon as i did, and received a stroke above the temple, which levelled him with the ground. we were alone, without arms, half a league from any habitation, on a vast plain bounded by the sea. the zambo, instead of attacking me, moved off slowly to pick up m. bonpland's hat, which, having somewhat deadened the violence of the blow, had fallen off and lay at some distance. alarmed at seeing my companion on the ground, and for some moments senseless, i thought of him only. i helped him to raise himself, and pain and anger doubled his strength. we ran toward the zambo, who, either from cowardice, common enough in people of this caste, or because he perceived at a distance some men on the beach, did not wait for us, but ran off in the direction of the tunal, a little thicket of cactus and arborescent avicennia. he chanced to fall in running; and m. bonpland, who reached him first, seized him round the body. the zambo drew a long knife; and in this unequal struggle we should infallibly have been wounded, if some biscayan merchants, who were taking the air on the beach, had not come to our assistance. the zambo seeing himself surrounded, thought no longer of defence. he again ran away, and we pursued him through the thorny cactuses. at length, tired out, he took shelter in a cow-house, whence he suffered himself to be quietly led to prison. m. bonpland was seized with fever during the night; but being endowed with great energy and fortitude, and possessing that cheerful disposition which is one of the most precious gifts of nature, he continued his labours the next day. the stroke of the macana had extended to the top of his head, and he felt its effect for the space of two or three months during the stay we made at caracas. when stooping to collect plants, he was sometimes seized with giddiness, which led us to fear that an internal abscess was forming. happily these apprehensions were unfounded, and the symptoms, at first alarming, gradually disappeared. the inhabitants of cumana showed us the kindest interest. it was ascertained that the zambo was a native of one of the indian villages which surround the great lake of maracaybo. he had served on board a privateer belonging to the island of st. domingo, and in consequence of a quarrel with the captain he had been left on the coast of cumana, when the ship quitted the port. having seen the signal which we had fixed up for the purpose of observing the height of the tides, he had watched the moment when he could attack us on the beach. but why, after having knocked one of us down, was he satisfied with simply stealing a hat? in an examination he underwent, his answers were so confused and stupid, that it was impossible to clear up our doubts. sometimes he maintained that his intention was not to rob us; but that, irritated by the bad treatment he had suffered on board the privateer of st. domingo, he could not resist the desire of attacking us, when he heard us speak french. justice is so tardy in this country, that prisoners, of whom the jail is full, may remain seven or eight years without being brought to trial; we learnt, therefore, with some satisfaction, that a few days after our departure from cumana, the zambo had succeeded in breaking out of the castle of san antonio. on the day after this occurrence, the th of october, i was, at five in the morning, on the terrace of our house, making preparations for the observation of the eclipse. the weather was fine and serene. the crescent of venus, and the constellation of the ship, so splendid from the disposition of its immense nebulae, were lost in the rays of the rising sun. i had a complete observation of the progress and the close of the eclipse. i determined the distance of the horns, or the differences of altitude and azimuth, by the passage over the threads of the quadrant. the eclipse terminated at hours minutes . seconds mean time, at cumana. during a few days which preceded and followed the eclipse of the sun, very remarkable atmospherical phenomena were observable. it was what is called in those countries the season of winter; that is, of clouds and small electrical showers. from the th of october to the rd of november, at nightfall, a reddish vapour arose in the horizon, and covered, in a few minutes, with a veil more or less thick, the azure vault of the sky. saussure's hygrometer, far from indicating greater humidity, often went back from to degrees. the heat of the day was from to degrees, which for this part of the torrid zone is very considerable. sometimes, in the midst of the night, the vapours disappeared in an instant; and at the moment when i had arranged my instruments, clouds of brilliant whiteness collected at the zenith, and extended towards the horizon. on the th of october these clouds were so remarkably transparent, that they did not hide stars even of the fourth magnitude. i could distinguish so perfectly the spots of the moon, that it might have been supposed its disk was before the clouds. the latter were at a prodigious height, disposed in bands, and at equal distances, as from the effect of electric repulsions:--these small masses of vapour, similar to those i saw above my head on the ridge of the highest andes, are, in several languages, designated by the name of sheep. when the reddish vapour spreads lightly over the sky, the great stars, which in general, at cumana, scarcely scintillate below or degrees, did not retain even at the zenith, their steady and planetary light. they scintillated at all altitudes, as after a heavy storm of rain.* (* i have not observed any direct relation between the scintillation of the stars and the dryness of that part of the atmosphere open to our researches. i have often seen at cumana a great scintillation of the stars of orion and sagittarius, when saussure's hygrometer was at degrees. at other times, these same stars, considerably elevated above the horizon, emitted a steady and planetary light, the hygrometer being at or degrees. probably it is not the quantity of vapour, but the manner in which it is diffused, and more or less dissolved in the air, which determines the scintillation. the latter is invariably attended with a coloration of light. it is remarkable enough, that, in northern countries, at a time when the atmosphere appears perfectly dry, the scintillation is most decided in very cold weather.) it was curious that the vapour did not affect the hygrometer at the surface of the earth. i remained a part of the night seated in a balcony, from which i had a view of a great part of the horizon. in every climate i feel a peculiar interest in fixing my eyes, when the sky is serene, on some great constellation, and seeing groups of vesicular vapours appear and augment, as around a central nucleus, then, disappearing, form themselves anew. after the th of october, the reddish mist became thicker than it had previously been. the heat of the nights seemed stifling, though the thermometer rose only to degrees. the breeze, which generally refreshed the air from eight or nine o'clock in the evening, was no longer felt. the atmosphere was burning hot, and the parched and dusty ground was cracked on every side. on the th of november, about two in the afternoon, large clouds of peculiar blackness enveloped the high mountains of the brigantine and the tataraqual. they extended by degrees as far as the zenith. about four in the afternoon thunder was heard over our heads, at an immense height, not regularly rolling, but with a hollow and often interrupted sound. at the moment of the strongest electric explosion, at hours minutes, there were two shocks of earthquake, which followed each other at the interval of fifteen seconds. the people ran into the streets, uttering loud cries. m. bonpland, who was leaning over a table examining plants, was almost thrown on the floor. i felt the shock very strongly, though i was lying in a hammock. its direction was from north to south, which is rare at cumana. slaves, who were drawing water from a well more than eighteen or twenty feet deep, near the river manzanares, heard a noise like the explosion of a strong charge of gunpowder. the noise seemed to come from the bottom of the well; a very curious phenomenon, though very common in most of the countries of america which are exposed to earthquakes. a few minutes before the first shock there was a very violent blast of wind, followed by electrical rain falling in great drops. i immediately tried the atmospherical electricity by the electrometer of volta. the small balls separated four lines; the electricity often changed from positive to negative, as is the case during storms, and, in the north of europe, even sometimes in a fall of snow. the sky remained cloudy, and the blast of wind was followed by a dead calm, which lasted all night. the sunset presented a picture of extraordinary magnificence. the thick veil of clouds was rent asunder, as in shreds, quite near the horizon; the sun appeared at degrees of altitude on a sky of indigo-blue. its disk was enormously enlarged, distorted, and undulated toward the edges. the clouds were gilded; and fascicles of divergent rays, reflecting the most brilliant rainbow hues, extended over the heavens. a great crowd of people assembled in the public square. this celestial phenomenon,--the earthquake,--the thunder which accompanied it,--the red vapour seen during so many days, all were regarded as the effect of the eclipse. about nine in the evening there was another shock, much slighter than the former, but attended with a subterraneous noise. the barometer was a little lower than usual; but the progress of the horary variations or small atmospheric tides, was no way interrupted. the mercury was precisely at the minimum of height at the moment of the earthquake; it continued rising till eleven in the evening, and sank again till half after four in the morning, conformably to the law which regulates barometrical variations. in the night between the rd and th of november the reddish vapour was so thick that i could not distinguish the situation of the moon, except by a beautiful halo of degrees diameter. scarcely twenty-two months had elapsed since the town of cumana had been almost totally destroyed by an earthquake. the people regard vapours which obscure the horizon, and the subsidence of wind during the night, as infallible pregnostics of disaster. we had frequent visits from persons who wished to know whether our instruments indicated new shocks for the next day; and alarm was great and general when, on the th of november, exactly at the same hour as on the preceding day, there was a violent gust of wind, attended by thunder, and a few drops of rain. no shock was felt. the wind and storm returned during five or six days at the same hour, almost at the same minute. the inhabitants of cumana, and of many other places between the tropics, have long since observed that atmospherical changes, which are, to appearance, the most accidental, succeed each other for whole weeks with astonishing regularity. the same phenomenon occurs in summer, in the temperate zone; nor has it escaped the perception of astronomers, who often observe, in a serene sky, during three or four days successively, clouds which have collected at the same part of the firmament, take the same direction, and dissolve at the same height; sometimes before, sometimes after the passage of a star over the meridian, consequently within a few minutes of the same point of true time.* (* m. arago and i paid a great deal of attention to this phenomenon during a long series of observations made in the year and , at the observatory of paris, with the view of verifying the declination of the stars.) the earthquake of the th of november, the first i had felt, made the greater impression on me, as it was accompanied with remarkable meteorological variations. it was, moreover, a positive movement upward and downward, and not a shock by undulation. i did not then imagine, that after a long abode on the table-lands of quito and the coasts of peru, i should become almost as familiar with the abrupt movements of the ground as we are in europe with the sound of thunder. in the city of quito, we never thought of rising from our beds when, during the night, subterraneous rumblings (bramidos), which seem always to come from the volcano of pichincha, announced a shock, the force of which, however, is seldom in proportion to the intensity of the noise. the indifference of the inhabitants, who bear in mind that for three centuries past their city has not been destroyed, readily communicates itself to the least intrepid traveller. it is not so much the fear of the danger, as the novelty of the sensation, which makes so forcible an impression when the effect of the slightest earthquake is felt for the first time. from our infancy, the idea of certain contrasts becomes fixed in our minds: water appears to us an element that moves; earth, a motionless and inert mass. these impressions are the result of daily experience; they are connected with everything that is transmitted to us by the senses. when the shock of an earthquake is felt, when the earth which we had deemed so stable is shaken on its old foundations, one instant suffices to destroy long-fixed illusions. it is like awakening from a dream; but a painful awakening. we feel that we have been deceived by the apparent stability of nature; we become observant of the least noise; we mistrust for the first time the soil we have so long trod with confidence. but if the shocks be repeated, if they become frequent during several successive days, the uncertainty quickly disappears. in , the inhabitants of mexico were accustomed to hear the thunder roll beneath their feet,* (* los bramidos de guanazuato.) as it is heard by us in the region of the clouds. confidence easily springs up in the human breast: on the coasts of peru we become accustomed to the undulations of the ground, as the sailor becomes accustomed to the tossing of the ship, caused by the motion of the waves. the reddish vapour which at cumana had spread a mist over the horizon a little before sunset, disappeared after the th of november. the atmosphere resumed its former purity, and the firmament appeared, at the zenith, of that deep blue tint peculiar to climates where heat, light, and a great equality of electric charge seem all to promote the most perfect dissolution of water in the air. i observed, on the night of the th, the immersion of the second satellite of jupiter. the belts of the planet were more distinct than i had ever seen them before. i passed a part of the night in comparing the intensity of the light emitted by the beautiful stars which shine in the southern sky. i pursued this task carefully in both hemispheres, at sea, and during my abode at lima, at guayaquil, and at mexico. nearly half a century has now elapsed since la caille examined that region of the sky which is invisible in europe. the stars near the south pole are usually observed with so little perseverance and attention, that the greatest changes may take place in the intensity of their light and their own motion, without astronomers having the slightest knowledge of them. i think i have remarked changes of this kind in the constellation of the crane and in that of the ship. i compared, at first with the naked eye, the stars which are not very distant from each other, for the purpose of classing them according to the method pointed out by herschel, in a paper read to the royal society of london in . i afterwards employed diaphragms diminishing the aperture of the telescope, and coloured and colourless glasses placed before the eye-glass. i moreover made use of an instrument of reflexion calculated to bring simultaneously two stars into the field of the telescope, after having equalized their light by receiving it with more or fewer rays at pleasure, reflected by the silvered part of the mirror. i admit that these photometric processes are not very precise; but i believe the last, which perhaps had never before been employed, might he rendered nearly exact, by adding a scale of equal parts to the moveable frame of the telescope of the sextant. it was by taking the mean of a great number of valuations, that i saw the relative intensity of the light of the great stars decrease in the following manner: sirius, canopus, a centauri, acherner, b centauri, fomalhaut, rigel, procyon, betelgueuse, e of the great dog, d of the great dog, a of the crane, a of the peacock. these experiments will become more interesting when travellers shall have determined anew, at intervals of forty or fifty years, some of those changes which the celestial bodies seem to undergo, either at their surface or with respect to their distances from our planetary system. after having made astronomical observations with the same instruments, in our northern climates and in the torrid zone, we are surprised at the effect produced in the latter (by the transparency of the air, and the less extinction of light), on the clearness with which the double stars, the satellites of jupiter, or certain nebulae, present themselves. beneath a sky equally serene in appearance, it would seem as if more perfect instruments were employed; so much more distinct and well defined do the objects appear between the tropics. it cannot be doubted, that at the period when equinoctial america shall become the centre of extensive civilization, physical astronomy will make immense improvements, in proportion as the skies will be explored with excellent glasses, in the dry and hot climates of cumana, coro, and the island of margareta. i do not here mention the ridge of the cordilleras, because, with the exception of some high and nearly barren plains in mexico and peru, the very elevated table-lands, in which the barometric pressure is from ten to twelve inches less than at the level of the sea, have a misty and extremely variable climate. the extreme purity of the atmosphere which constantly prevails in the low regions during the dry season, counterbalances the elevation of site and the rarity of the air on the table-lands. the elevated strata of the atmosphere, when they envelope the ridges of mountains, undergo rapid changes in their transparency. the night of the th of november was cool and extremely fine. from half after two in the morning, the most extraordinary luminous meteors were seen in the direction of the east. m. bonpland, who had risen to enjoy the freshness of the air, perceived them first. thousands of bolides and falling stars succeeded each other during the space of four hours. their direction was very regular from north to south. they filled a space in the sky extending from due east degrees to north and south. in an amplitude of degrees the meteors were seen to rise above the horizon at east-north-east and at east, to describe arcs more or less extended, and to fall towards the south, after having followed the direction of the meridian. some of them attained a height of degrees, and all exceeded or degrees. there was very little wind in the low regions of the atmosphere, and that little blew from the east. no trace of clouds was to be seen. m. bonpland states that, from the first appearance of the phenomenon, there was not in the firmament a space equal in extent to three diameters of the moon, which was not filled every instant with bolides and falling stars. the first were fewer in number, but as they were of different sizes, it was impossible to fix the limit between these two classes of phenomena. all these meteors left luminous traces from five to ten degrees in length, as often happens in the equinoctial regions. the phosphorescence of these traces, or luminous bands, lasted seven or eight seconds. many of the falling stars had a very distinct nucleus, as large as the disk of jupiter, from which darted sparks of vivid light. the bolides seem to burst as by explosion; but the largest, those from to degree minutes in diameter, disappeared without scintillation, leaving behind them phosphorescent bands (trabes) exceeding in breadth fifteen or twenty minutes. the light of these meteors was white, and not reddish, which must doubtless be attributed to the absence of vapour and the extreme transparency of the air. for the same reason, within the tropics, the stars of the first magnitude have, at their rising, a light decidedly whiter than in europe. almost all the inhabitants of cumana witnessed this phenomenon, because they had left their houses before four o'clock, to attend the early morning mass. they did not behold these bolides with indifference; the oldest among them remembered that the great earthquakes of were preceded by similar phenomena. the guaiqueries in the indian suburb alleged "that the bolides began to appear at one o'clock; and that as they returned from fishing in the gulf, they had perceived very small falling stars towards the east." they assured us that igneous meteors were extremely rare on those coasts after two o'clock in the morning. the phenomenon ceased by degrees after four o'clock, and the bolides and falling stars became less frequent; but we still distinguished some to north-east by their whitish light, and the rapidity of their movement, a quarter of an hour after sunrise. this circumstance will appear less extraordinary, when i mention that in broad daylight, in , the interior of the houses in the town of popayan was brightly illumined by an aerolite of immense magnitude. it passed over the town, when the sun was shining clearly, about one o'clock. m. bonpland and myself, during our second residence at cumana, after having observed, on the th of september, , the immersion of the first satellite of jupiter, succeeded in seeing the planet distinctly with the naked eye, eighteen minutes after the disk of the sun had appeared in the horizon. there was a very slight vapour in the east, but jupiter appeared on an azure sky. these facts bear evidence of the extreme purity and transparency of the atmosphere in the torrid zone. the mass of diffused light is the less, in proportion as the vapours are more perfectly dissolved. the same cause which checks the diffusion of the solar light, diminishes the extinction of that which emanates either from bolides from jupiter, or from the moon, seen on the second day after its conjunction. the th of november was an extremely hot day, and the hygrometer indicated a very considerable degree of dryness for those climates. the reddish vapour clouded the horizon anew, and rose to the height of degrees. this was the last time it appeared that year; and i must here observe, that it is no less rare under the fine sky of cumana, than it is common at acapulco, on the western coast of mexico. we did not neglect, during the course of our journey from caracas to the rio negro, to enquire everywhere, whether the meteors of the th of november had been perceived. in a wild country, where the greater number of the inhabitants sleep in the open air, so extraordinary a phenomenon could not fail to be remarked, unless it had been concealed from observation by clouds. the capuchin missionary at san fernando de apure,* (* north latitude degrees minutes seconds; west longitude degrees minutes.), a village situated amid the savannahs of the province of varinas; the franciscan monks stationed near the cataracts of the orinoco and at maroa,* (* north latitude degrees minutes seconds; west longitude degrees minutes.) on the banks of the rio negro; had seen numberless falling-stars and bolides illumine the heavens. maroa is south-west of cumana, at one hundred and seventy-four leagues distance. all these observers compared the phenomenon to brilliant fireworks; and it lasted from three till six in the morning. some of the monks had marked the day in their rituals; others had noted it by the proximate festivals of the church. unfortunately, none of them could recollect the direction of the meteors, or their apparent height. from the position of the mountains and thick forests which surround the missions of the cataracts and the little village of maroa, i presume that the bolides were still visible at degrees above the horizon. on my arrival at the southern extremity of spanish guiana, at the little fort of san carlos, i found some portuguese, who had gone up the rio negro from the mission of st. joseph of the maravitans. they assured me that in that part of brazil the phenomenon had been perceived at least as far as san gabriel das cachoeiras, consequently as far as the equator itself.* (* a little to the north-west of san antonio de castanheiro. i did not meet with any persons who had observed this meteor, at santa fe de bogota, at popayan, or in the southern hemisphere, at quito and peru. perhaps the state of the atmosphere, so changeable in these western regions, prevented observation.) i was forcibly struck by the immense height which these bolides must have attained, to have rendered them visible simultaneously at cumana, and on the frontiers of brazil, in a line of two hundred and thirty leagues in length. but what was my astonishment, when, on my return to europe, i learned that the same phenomenon had been perceived on an extent of the globe of degrees of latitude, and degrees of longitude; at the equator, in south america, at labrador, and in germany! i saw accidentally, during my passage from philadelphia to bordeaux,* (* in the memoirs of the pennsylvanian society.) the corresponding observation of mr. ellicot (latitude degrees ); and upon my return from naples to berlin, i read the account of the moravian missionaries among the esquimaux, in the bibliothek of gottingen. the following is a succinct enumeration of the facts: first. the fiery meteors were seen in the east, and the east-north-east, at degrees of elevation, from to a.m. at cumana (latitude degrees minutes seconds, longitude degrees minutes); at porto cabello (latitude degrees minutes seconds, longitude degrees minutes); and on the frontiers of brazil, near the equator, in longitude degrees west of the meridian of paris. second. in french guiana (latitude degrees minutes, longitude degrees minutes) "the northern part of the sky was suffused with fire. numberless falling-stars traversed the heavens during the space of an hour and a half, and shed so vivid a light, that those meteors might be compared to the blazing sheaves which shoot out from fireworks." the knowledge of this fact rests upon the highly trustworthy testimony of the count de marbois, then living in exile at cayenne, a victim to his love of justice and of rational, constitutional liberty. third. mr. ellicot, astronomer to the united states, having completed his trigonometric operations for the rectification of the limits on the ohio, being on the th of november in the gulf of florida, in latitude degrees, and longitude degrees minutes, saw in all parts of the sky, "as many meteors as stars, moving in all directions. some appeared to fall perpendicularly; and it was expected every minute that they would drop into the vessel." the same phenomenon was perceived upon the american continent as far as latitude degrees minutes. fourth. in labrador, at nain (latitude degrees minutes), and hoffenthal (latitude degrees minutes); in greenland, at lichtenau (latitude degrees minutes), and at new herrnhut (latitude degrees minutes, longitude degrees minutes); the esquimaux were terrified at the enormous quantity of bolides which fell during twilight at all points of the firmament, and some of which were said to be a foot broad. fifth. in germany, mr. zeissing, vicar of ittetsadt, near weimar (latitude degrees minutes, longitude degrees minute east), perceived, on the th of november, between the hours of six and seven in the morning (half-past two at cumana), some falling-stars which shed a very white light. soon after, in the direction of south and south-west, luminous rays appeared from four to six feet long; they were reddish, and resembled the luminous track of a sky-rocket. during the morning twilight, between the hours of seven and eight, the sky, in the direction of south-west, was observed from time to time to be brightly illumined by white lightning, running in serpentine lines along the horizon. at night the cold increased and the barometer rose. it is very probable, that the meteors might have been observed more to the east, in poland and in russia.* (* in paris and in london the sky was cloudy. at carlsruhe, before dawn, lightning was seen in the north-west and south-east. on the th of november a remarkable glare of light was seen at the same place in the south-east.) the distance from weimar to the rio negro is nautical leagues; and from the rio negro to herrnhut in greenland, leagues. admitting that the same fiery meteors were seen at points so distant from each other, we must suppose that their height was at least leagues. near weimar, the appearance like sky-rockets was observed in the south and south-east; at cumana, in the east and east-north-east. we may therefore conclude, that numberless aerolites must have fallen into the sea, between africa and south america, westward of the cape verd islands. but since the direction of the bolides was not the same at labrador and at cumana, why were they not perceived in the latter place towards the north, as at cayenne? we can scarcely be too cautious on a subject, on which good observations made in very distant places are still wanting. i am rather inclined to think, that the chayma indians of cumana did not see the same bolides as the portuguese in brazil and the missionaries in labrador; but at the same time it cannot be doubted (and this fact appears to me very remarkable) that in the new world, between the meridians of and degrees, between the equator and degrees north, at the same hour, an immense number of bolides and falling-stars were perceived; and that those meteors had everywhere the same brilliancy, throughout a space of , square leagues. astronomers who have lately been directing minute attention to falling-stars and their parallaxes, consider them as meteors belonging to the farthest limits of our atmosphere, between the region of the aurora borealis and that of the lightest clouds.* (* according to the observations which i made on the ridge of the andes, at an elevation of toises, on the moutons, or little white fleecy clouds, it appeared to me, that their elevation is sometimes not less than toises above the level of the coast.) some have been seen, which had not more than , toises, or about five leagues of elevation. the highest do not appear to exceed thirty leagues. they are often more than a hundred feet in diameter: and their swiftness is such, that they dart in a few seconds through a space of two leagues. of some which have been measured, the direction was almost perpendicularly upward, or forming an angle of degrees with the vertical line. this extremely remarkable circumstance has led to the conclusion, that falling-stars are not aerolites which, after having hovered a long time in space, unite on accidentally entering into our atmosphere, and fall towards the earth.* (* m. chladni, who at first considered falling-stars to be aerolites, subsequently abandoned that idea.) whatever may be the origin of these luminous meteors, it is difficult to conceive an instantaneous inflammation taking place in a region where there is less air than in the vacuum of our air-pumps; and where (at the height of , toises) the mercury in the barometer would not rise to . of a line. we have ascertained the uniform mixture of atmospheric air to be about . , only to an elevation of toises; consequently not beyond the last stratum of fleecy clouds. it may be admitted that, in the first revolutions of the globe, gaseous substances, which yet remain unknown to us, have risen towards that region through which the falling-stars pass; but accurate experiments, made upon mixtures of gases which have not the same specific gravity, show that there is no reason for supposing a superior stratum of the atmosphere entirely different from the inferior strata. gaseous substances mingle and penetrate each other on the least movement; and a uniformity of their mixture may have taken place in the lapse of ages, unless we believe them to possess a repulsive action of which there is no example in those substances we can subject to our observations. farther, if we admit the existence of particular aerial fluids in the inaccessible regions of luminous meteors, of falling-stars, bolides, and the aurora borealis; how can we conceive why the whole stratum of those fluids does not at once ignite, but that the gaseous emanations, like the clouds, occupy only limited spaces? how can we suppose an electrical explosion without some vapours collected together, capable of containing unequal charges of electricity, in air, the mean temperature of which is perhaps degrees below the freezing point of the centigrade thermometer, and the rarefaction of which is so considerable, that the compression of the electrical shock could scarcely disengage any heat? these difficulties would in great part be removed, if the direction of the movement of falling-stars allowed us to consider them as bodies with a solid nucleus, as cosmic phenomena (belonging to space beyond the limits of our atmosphere), and not as telluric phenomena (belonging to our planet only). supposing the meteors of cumana to have been only at the usual height at which falling-stars in general move, the same meteors were seen above the horizon in places more than leagues distant from each other.* (* it was this circumstance that induced lambert to propose the observation of falling-stars for the determination of terrestrial longitudes. he considered them to be celestial signals seen at great distances.) how great a disposition to incandescence must have prevailed on the th november, in the higher regions of the atmosphere, to have rendered during four hours myriads of bolides and falling stars visible at the equator, in greenland, and in germany! m. benzenberg observes, that the same cause which renders the phenomenon more frequent, has also an influence on the large size of the meteors, and the intensity of their light. in europe, the greatest number of falling stars are seen on those nights on which very bright ones are mingled with very small ones. the periodical nature of the phenomenon augments the interest it excites. there are months in which m. brandes has reckoned in our temperate zone only sixty or eighty falling-stars in one night; and in other months their number has risen to two thousand. whenever one is observed, which has the diameter of sirius or of jupiter, we are sure of seeing the brilliant meteor succeeded by a great number of smaller ones. if the falling stars be very numerous during one night, it is probable that they will continue equally so during several weeks. it would seem, that in the higher regions of the atmosphere, near that extreme limit where the centrifugal force is balanced by gravity, there exists at regular periods a particular disposition for the production of bolides, falling-stars, and the aurora borealis.* (* ritter, like several others, makes a distinction between bolides mingled with falling-stars and those luminous meteors which, enveloped in vapour and smoke, explode with great noise, and let fall (chiefly in the day-time) aerolites. the latter certainly do not belong to our atmosphere.) does the periodical recurrence of this great phenomenon depend upon the state of the atmosphere? or upon something which the atmosphere receives from without, while the earth advances in the ecliptic? of all this we are still as ignorant as mankind were in the days of anaxagoras. with respect to the falling-stars themselves, it appears to me, from my own experience, that they are more frequent in the equinoctial regions than in the temperate zone; and more frequent above continents, and near certain coasts, than in the middle of the ocean. do the radiation of the surface of the globe, and the electric charge of the lower regions of the atmosphere (which varies according to the nature of the soil and the positions of the continents and seas), exert their influence as far as those heights where eternal winter reigns? the total absence of even the smallest clouds, at certain seasons, or above some barren plains destitute of vegetation, seems to prove that this influence can be felt as far as five or six thousand toises high. a phenomenon analogous to that which appeared on the th of november at cumana, was observed thirty years previously on the table-land of the andes, in a country studded with volcanoes. in the city of quito there was seen in one part of the sky, above the volcano of cayamba, such great numbers of falling-stars, that the mountain was thought to be in flames. this singular sight lasted more than an hour. the people assembled in the plain of exido, which commands a magnificent view of the highest summits of the cordilleras. a procession was on the point of setting out from the convent of san francisco, when it was perceived that the blaze on the horizon was caused by fiery meteors, which ran along the skies in all directions, at the altitude of twelve or thirteen degrees. chapter . . passage from cumana to la guayra. morro of nueva barcelona. cape codera. road from la guayra to caracas. on the th of november, at eight in the evening, we were under sail to proceed along the coast from cumana to the port of la guayra, whence the inhabitants of the province of venezuela export the greater part of their produce. the passage is only a distance of sixty leagues, and it usually occupies from thirty-six to forty hours. the little coasting vessels are favoured at once by the wind and by the currents, which run with more or less force from east to west, along the coasts of terra firma, particularly from cape paria to the cape of chichibacoa. the road by land from cumana to new barcelona, and thence to caracas, is nearly in the same state as that in which it was before the discovery of america. the traveller has to contend with the obstacles presented by a miry soil, large scattered rocks, and strong vegetation. he must sleep in the open air, pass through the valleys of the unare, the tuy, and the capaya, and cross torrents which swell rapidly on account of the proximity of the mountains. to these obstacles must be added the dangers arising from the extreme insalubrity of the country. the very low lands, between the sea-shore and the chain of hills nearest the coast, from the bay of mochima as far as coro, are extremely unhealthy. but the last-mentioned town, which is surrounded by an immense wood of thorny cactuses, owes its great salubrity, like cumana, to its barren soil and the absence of rain. in returning from caracas to cumana, the road by land is sometimes preferred to the passage by sea, to avoid the adverse current. the postman from caracas is nine days in performing this journey. we often saw persons, who had followed him, arrive at cumana ill of nervous and miasmatic fevers. the tree of which the bark* furnishes a salutary remedy for those fevers (* cortex angosturae of our pharmacopaeias, the bark of the bonplandia trifoliata.), grows in the same valleys, and upon the edge of the same forests which send forth the pernicious exhalations. m. bonpland recognised the cuspare in the vegetation of the gulf of santa fe, situated between the ports of cumana and barcelona. the sickly traveller may perchance repose in a cottage, the inhabitants of which are ignorant of the febrifuge qualities of the trees that shade the surrounding valleys. having proceeded by sea from cumana to la guayra, we intended to take up our abode in the town of caracas, till the end of the rainy season. from caracas we proposed to direct our course across the great plains or llanos, to the missions of the orinoco; to go up that vast river, to the south of the cataracts, as far as the rio negro and the frontiers of brazil; and thence to return to cumana by the capital of spanish guiana, commonly called, on account of its situation, angostura, or the strait. we could not determine the time we might require to accomplish a tour of seven hundred leagues, more than two-thirds of that distance having to be traversed in boats. the only parts of the orinoco known on the coasts are those near its mouth. no commercial intercourse is kept up with the missions. the whole of the country beyond the llanos is unknown to the inhabitants of cumana and caracas. some think that the plains of calabozo, covered with turf, stretch eight hundred leagues southward, communicating with the steppes or pampas of buenos ayres; others, recalling to mind the great mortality which prevailed among the troops of iturriaga and solano, during their expedition to the orinoco, consider the whole country, south of the cataracts of atures, as extremely pernicious to health. in a region where travelling is so uncommon, people seem to feel a pleasure in exaggerating to strangers the difficulties arising from the climate, the wild animals, and the indians. nevertheless we persisted in the project we had formed. we could rely upon the interest and solicitude of the governor of cumana, don vicente emparan, as well as on the recommendations of the franciscan monks, who are in reality masters of the shores of the orinoco. fortunately for us, one of those monks, juan gonzales, was at that time in cumana. this young monk, who was only a lay-brother, was highly intelligent, and full of spirit and courage. he had the misfortune shortly after his arrival on the coast to displease his superiors, upon the election of a new director of the missions of piritu, which is a period of great agitation in the convent of new barcelona. the triumphant party exercised a general retaliation, from which the lay-brother could not escape. he was sent to esmeralda, the last mission of the upper orinoco, famous for the vast quantity of noxious insects with which the air is continually filled. fray juan gonzales was thoroughly acquainted with the forests which extend from the cataracts towards the sources of the orinoco. another revolution in the republican government of the monks had some years before brought him to the coast, where he enjoyed (and most justly) the esteem of his superiors. he confirmed us in our desire of examining the much-disputed bifurcation of the orinoco. he gave us useful advice for the preservation of our health, in climates where he had himself suffered long from intermitting fevers. we had the satisfaction of finding fray juan gonzales at new barcelona, on our return from the rio negro. intending to go from the havannah to cadiz, he obligingly offered to take charge of part of our herbals, and our insects of the orinoco; but these collections were unfortunately lost with himself at sea. this excellent young man, who was much attached to us, and whose zeal and courage might have rendered him very serviceable to the missions of his order, perished in a storm on the coast of africa, in . the boat which conveyed us from cumana to la guayra, was one of those employed in trading between the coasts and the west india islands. they are thirty feet long, and not more than three feet high at the gunwale; they have no decks, and their burthen is generally from two hundred to two hundred and fifty quintals. although the sea is extremely rough from cape codera to la guayra, and although the boats have an enormous triangular sail, somewhat dangerous in those gusts which issue from the mountain-passes, no instance has occurred during thirty years, of one of these boats being lost in the passage from cumana to the coast of caracas. the skill of the guaiqueria pilots is so great, that accidents are very rare, even in the frequent trips they make from cumana to guadaloupe, or the danish islands, which are surrounded with breakers. these voyages of or leagues, in an open sea, out of sight of land, are performed in boats without decks, like those of the ancients, without observations of the meridian altitude of the sun, without charts, and generally without a compass. the indian pilot directs his course at night by the pole-star, and in the daytime by the sun and the wind. i have seen guaiqueries and pilots of the zambo caste, who could find the pole-star by the direction of the pointers alpha and beta of the great bear, and they seemed to me to steer less from the view of the pole-star itself, than from the line drawn through these stars. it is surprising, that at the first sight of land, they can find the island of guadaloupe, santa cruz, or porto rico; but the compensation of the errors of their course is not always equally fortunate. the boats, if they fall to leeward in making land, beat up with great difficulty to the eastward, against the wind and the current. we descended rapidly the little river manzanares, the windings of which are marked by cocoa-trees, as the rivers of europe are sometimes bordered by poplars and old willows. on the adjacent arid land, the thorny bushes, on which by day nothing is visible but dust, glitter during the night with thousands of luminous sparks. the number of phosphorescent insects augments in the stormy season. the traveller in the equinoctial regions is never weary of admiring the effect of those reddish and moveable fires, which, being reflected by limpid water, blend their radiance with that of the starry vault of heaven. we quitted the shore of cumana as if it had long been our home. this was the first land we had trodden in a zone, towards which my thoughts had been directed from earliest youth. there is a powerful charm in the impression produced by the scenery and climate of these regions; and after an abode of a few months we seemed to have lived there during a long succession of years. in europe, the inhabitant of the north feels an almost similar emotion, when he quits even after a short abode the shores of the bay of naples, the delicious country between tivoli and the lake of nemi, or the wild and majestic scenery of the upper alps and the pyrenees. yet everywhere in the temperate zone, the effects of vegetable physiognomy afford little contrast. the firs and the oaks which crown the mountains of sweden have a certain family air in common with those which adorn greece and italy. between the tropics, on the contrary, in the lower regions of both indies, everything in nature appears new and marvellous. in the open plains and amid the gloom of forests, almost all the remembrances of europe are effaced; for it is vegetation that determines the character of a landscape, and acts upon the imagination by its mass, the contrast of its forms, and the glow of its colours. in proportion as impressions are powerful and new, they weaken antecedent impressions, and their force imparts to them the character of duration. i appeal to those who, more sensible to the beauties of nature than to the charms of society, have long resided in the torrid zone. how dear, how memorable during life, is the land on which they first disembarked! a vague desire to revisit that spot remains rooted in their minds to the most advanced age. cumana and its dusty soil are still more frequently present to my imagination, than all the wonders of the cordilleras. beneath the bright sky of the south, the light, and the magic of the aerial hues, embellish a land almost destitute of vegetation. the sun does not merely enlighten, it colours the objects, and wraps them in a thin vapour, which, without changing the transparency of the air, renders its tints more harmonious, softens the effects of the light, and diffuses over nature a placid calm, which is reflected in our souls. to explain this vivid impression which the aspect of the scenery in the two indies produces, even on coasts but thinly wooded, it is sufficient to recollect that the beauty of the sky augments from naples to the equator, almost as much as from provence to the south of italy. we passed at high water the bar formed at the mouth of the little river manzanares. the evening breeze gently swelled the waves in the gulf of cariaco. the moon had not risen, but that part of the milky way which extends from the feet of the centaur towards the constellation of sagittarius, seemed to pour a silvery light over the surface of the ocean. the white rock, crowned by the castle of san antonio, appeared from time to time between the high tops of the cocoa-trees which border the shore; and we soon recognized the coasts only by the scattered lights of the guaiqueria fishermen. we sailed at first to north-north-west, approaching the peninsula of araya; we then ran thirty miles to west and west-south-west. as we advanced towards the shoal that surrounds cape arenas and stretches as far as the petroleum springs of maniquarez, we enjoyed one of those varied sights which the great phosphorescence of the sea so often displays in those climates. bands of porpoises followed our bark. fifteen or sixteen of these animals swam at equal distances from each other. when turning on their backs, they struck the surface of the water with their broad tails; they diffused a brilliant light, which seemed like flames issuing from the depth of the ocean.* (* see views of nature bohn's edition page .) each band of porpoises, ploughing the surface of the waters, left behind it a track of light, the more striking as the rest of the sea was not phosphorescent. as the motion of an oar, and the track of the bark, produced on that night but feeble sparks, it is natural to suppose that the vivid phosphorescence caused by the porpoises was owing not only to the stroke of their tails, but also to the gelatinous matter that envelopes their bodies, and is detached by the shock of the waves. we found ourselves at midnight between some barren and rocky islands, which uprise like bastions in the middle of the sea, and form the group of the caracas and chimanas.* (* there are three of the caracas islands and eight of the chimanas.) the moon was above the horizon, and lighted up these cleft rocks which are bare of vegetation and of fantastic aspect. the sea here forms a sort of bay, a slight inward curve of the land between cumana and cape codera. the islets of picua, picuita, caracas, and boracha, appear like fragments of the ancient coast, which stretches from bordones in the same direction east and west. the gulfs of mochima and santa fe, which will no doubt one day become frequented ports, lie behind those little islands. the rents in the land, the fracture and dip of the strata, all here denote the effects of a great revolution: possibly that which clove asunder the chain of the primitive mountains, and separated the mica-schist of araya and the island of margareta from the gneiss of cape codera. several of the islands are visible at cumana, from the terraces of the houses, and they produce, according to the superposition of layers of air more or less heated, the most singular effects of suspension and mirage. the height of the rocks does not probably exceed one hundred and fifty toises; but at night, when lighted by the moon, they seem to be of a very considerable elevation. it may appear extraordinary, to find the caracas islands so distant from the city of that name, opposite the coast of the cumanagotos; but the denomination of caracas denoted at the beginning of the conquest, not a particular spot, but a tribe of indians, neighbours of the tecs, the taramaynas, and the chagaragates. as we came very near this group of mountainous islands, we were becalmed; and at sunrise, small currents drifted us toward boracha, the largest of them. as the rocks rise nearly perpendicular, the shore is abrupt; and in a subsequent voyage i saw frigates at anchor almost touching the land. the temperature of the atmosphere became sensibly higher whilst we were sailing among the islands of this little archipelago. the rocks, heated during the day, throw out at night, by radiation, a part of the heat absorbed. as the sun arose on the horizon, the rugged mountains projected their vast shadows on the surface of the ocean. the flamingoes began to fish in places where they found in a creek calcareous rocks bordered by a narrow beach. all these islands are now entirely uninhabited; but upon one of the caracas are found wild goats of large size, brown, and extremely swift. our indian pilot assured us that their flesh has an excellent flavour. thirty years ago a family of whites settled on this island, where they cultivated maize and cassava. the father alone survived his children. as his wealth increased, he purchased two black slaves; and by these slaves he was murdered. the goats became wild, but the cultivated plants perished. maize in america, like wheat in europe, connected with man since his first migrations, appears to be preserved only by his care. we sometimes see these nutritive gramina disseminate themselves; but when left to nature the birds prevent their reproduction by destroying the seeds. we anchored for some hours in the road of new barcelona, at the mouth of the river neveri, of which the indian (cumanagoto) name is enipiricuar. this river is full of crocodiles, which sometimes extend their excursions into the open sea, especially in calm weather. they are of the species common in the orinoco, and bear so much resemblance to the crocodile of egypt, that they have long been confounded together. it may easily be conceived that an animal, the body of which is surrounded with a kind of armour, must be nearly indifferent to the saltness of the water. pigafetta relates in his journal recently published at milan that he saw, on the shores of the island of borneo, crocodiles which inhabit alike land and sea. these facts must be interesting to geologists, since attention has been fixed on the fresh-water formations, and the curious mixture of marine and fluviatile petrifactions sometimes observed in certain very recent rocks. the port of barcelona has maintained a very active commerce since . from barcelona is exported most of the produce of those vast steppes which extend from the south side of the chain of the coast as far as the orinoco, and in which cattle of every kind are almost as abundant as in the pampas of buenos ayres. the commercial industry of these countries depends on the demand in the west india islands for salted provision, oxen, mules, and horses. the coasts of terra firma being opposite to the island of cuba, at a distance of fifteen or eighteen days' sail, the merchants of the havannah prefer, especially in time of peace, obtaining their provision from the port of barcelona, to the risk of a long voyage in another hemisphere to the mouth of the rio de la plata. the situation of barcelona is singularly advantageous for the trade in cattle. the animals have only three days' journey from the llanos to the port, while it requires eight or nine days to reach cumana, on account of the chain of mountains of the brigantine and the imposible. having landed on the right bank of the neveri, we ascended to a little fort called el morro de barcelona, situated at the elevation of sixty or seventy toises above the level of the sea. the morro is a calcareous rock which has been lately fortified. the view from the summit of the morro is not without beauty. the rocky island of boracha lies on the east, the lofty promontory of unare is on the west, and below are seen the mouth of the river neveri, and the arid shores on which the crocodiles come to sleep in the sun. notwithstanding the extreme heat of the air, for the thermometer, exposed to the reflection of the white calcareous rock, rose to degrees, we traversed the whole of the eminence. a fortunate chance led us to observe some very curious geological phenomena, which we again met with in the cordilleras of mexico. the limestone of barcelona has a dull, even, or conchoidal fracture, with very flat cavities. it is divided into very thin strata, and exhibits less analogy with the limestone of cumanacoa, than with that of caripe, forming the cavern of the guacharo. it is traversed by banks of schistose jasper,* (kieselschiefer of werner. )* black, with a conchoidal fracture, and breaking into fragments of a parallelopipedal figure. this fossil does not exhibit those little streaks of quartz so common in the lydian stone. it is found decomposed at its surface into a yellowish grey crust, and it does not act upon the magnet. its edges, a little translucid, give it some resemblance to the hornstone, so common in secondary limestones.* (* in switzerland, the hornstone passing into common jasper is found in kidney-stones, and in layers both in the alpine and jura limestone, especially in the former.) it is remarkable that we find the schistose jasper which in europe characterizes the transition rocks,* (the transition-limestone and schist.) in a limestone having great analogy with that of jura. in the study of formations, which is the great end of geognosy, the knowledge acquired in the old and new worlds should be made to furnish reciprocal aid to each other. it appears that these black strata are found also in the calcareous mountains of the island of boracha.* (* we saw some of it as ballast, in a fishing boat at punta araya. its fragments might have been mistaken for basalt.) another jasper, that known by the name of the egyptian pebble, was found by m. bonpland near the indian village of curacatiche or curacaguitiche, fifteen leagues south of the morro of barcelona, when, on our return from the orinoco, we crossed the llanos, and approached the mountains on the coast. this stone presented yellowish concentric lines and bands, on a reddish brown ground. it appeared to me that the round pieces of egyptian jasper belonged also to the barcelona limestone. yet, according to m. cordier, the fine pebbles of suez owe their origin to a breccia formation, or siliceous agglomerate. at the moment of our setting sail, on the th of november, at noon, i took some altitudes of the moon, to determine the longitude of the morro. the difference of meridian between cumana and the town of barcelona, where i made a great number of astronomical observations in , is minutes seconds. i found the dip of the needle . degrees: the intensity of the forces was equal to oscillations. from the morro of barcelona to cape codera, the land becomes low, as it recedes southward; and the soundings extend to the distance of three miles. beyond this we find the bottom at forty-five or fifty fathoms. the temperature of the sea at its surface was . degrees; but when we were passing through the narrow channel which separates the two piritu islands, in three fathoms water, the thermometer was only . degrees. the difference would perhaps be greater, if the current, which runs rapidly westward, stirred up deeper water; and if, in a pass of such small width, the land did not contribute to raise the temperature of the sea. the piritu islands resemble those shoals which become visible when the tide falls. they do not rise more than eight or nine inches above the mean height of the sea. their surface is smooth, and covered with grass. we might have thought we were gazing on some of our own northern meadows. the disk of the setting sun appeared like a globe of fire suspended over the savannah; and its last rays, as they swept the earth, illumined the grass, which was at the same time agitated by the evening breeze. in the low and humid parts of the equinoctial zone, even when the gramineous plants and reeds present the aspect of a meadow, a rich accessory of the picture is usually wanting; i allude to that variety of wild flowers, which, scarcely rising above the grass, seem as it were, to lie upon a smooth bed of verdure. within the tropics, the strength and luxury of vegetation give such a development to plants, that the smallest of the dicotyledonous family become shrubs. it would seem as if the liliaceous plants, mingling with the gramina, assumed the place of the flowers of our meadows. their form is indeed striking; they dazzle by the variety and splendour of their colours; but being too high above the soil, they disturb that harmonious proportion which characterizes the plants of our european meadows. nature has in every zone stamped on the landscape the peculiar type of beauty proper to the locality. we must not be surprised that fertile islands, so near terra firma, are not now inhabited. it was only at the early period of the discovery, and whilst the caribbees, chaymas, and cumanagotos were still masters of the coast, that the spaniards formed settlements at cubagua and margareta. when the natives were subdued, or driven southward in the direction of the savannahs, the preference was given to settlements on the continent, where there was a choice of land, and where there were indians, who might be treated like beasts of burden. had the little islands of tortuga, blanquilla, and orchilla been situated in the group of the antilles, they would not have remained without traces of cultivation. vessels of heavy burthen pass between the main land and the most southern of the piritu islands. being very low, their northern point is dreaded by pilots who near the coast in those latitudes. when we found ourselves to westward of the morro of barcelona, and the mouth of the river unare, the sea, till then calm, became agitated and rough in proportion as we approached cape codera. the influence of that vast promontory is felt from afar, in that part of the caribbean sea. the length of the passage from cumana to la guayra depends on the degree of ease or difficulty with which cape codera can be doubled. beyond this cape the sea constantly runs so high, that we can scarcely believe we are near a coast where (from the point of paria as far as cape san roman) a gale of wind is never known. on the th of november at sunrise we were so far advanced, that we might expect to double the cape in a few hours. we hoped to reach la guayra the same day; but our indian pilot being afraid of the privateers who were near that port, thought it would be prudent to make for land, and anchor in the little harbour of higuerote, which we had already passed, and await the shelter of night to proceed on our voyage. on the th of november at nine in the morning we were at anchor in the bay just mentioned, situated westward of the mouth of the rio capaya. we found there neither village nor farm, but merely two or three huts, inhabited by mestizo fishermen. their livid hue, and the meagre condition of their children, sufficed to remind us that this spot is one of the most unhealthy of the whole coast. the sea has so little depth along these shores, that even with the smallest barks it is impossible to reach the shore without wading through the water. the forests come down nearly to the beach, which is covered with thickets of mangroves, avicennias, manchineel-trees, and that species of suriana which the natives call romero de la mar.* (* suriana maritima.) to these thickets, and particularly to the exhalations of the mangroves, the extreme insalubrity of the air is attributed here, as in other places in both indies. on quitting the boats, and whilst we were yet fifteen or twenty toises distant from land, we perceived a faint and sickly smell, which reminded me of that diffused through the galleries of deserted mines, where the lights begin to be extinguished, and the timber is covered with flocculent byssus. the temperature of the air rose to degrees, heated by the reverberation from the white sands which form a line between the mangroves and the great trees of the forest. as the shore descends with a gentle slope, small tides are sufficient alternately to cover and uncover the roots and part of the trunks of the mangroves. it is doubtless whilst the sun heats the humid wood, and causes the fermentation, as it were, of the ground, of the remains of dead leaves and of the molluscs enveloped in the drift of floating seaweed, that those deleterious gases are formed, which escape our researches. we observed that the sea-water, along the whole coast, acquired a yellowish brown tint, wherever it came into contact with the mangrove trees. struck with this phenomenon, i gathered at higuerote a considerable quantity of branches and roots, for the purpose of making some experiments on the infusion of the mangrove, on my arrival at caracas. the infusion in warm water had a brown colour and an astringent taste. it contained a mixture of extractive matter and tannin. the rhizophora, the mistletoe, the cornel-tree, in short, all the plants which belong to the natural families of the lorantheous and the caprifoliaceous plants, have the same properties. the infusion of mangrove-wood, kept in contact with atmospheric air under a glass jar for twelve days, was not sensibly deteriorated in purity. a little blackish flocculent sediment was formed, but it was attended by no sensible absorption of oxygen. the wood and roots of the mangrove placed under water were exposed to the rays of the sun. i tried to imitate the daily operations of nature on the coasts at the rise of the tide. bubbles of air were disengaged, and at the expiration of ten days they formed a volume of thirty-three cubic inches. they were a mixture of azotic gas and carbonic acid. nitrous gas scarcely indicated the presence of oxygen.* (* in a hundred parts there were eighty-four of nitrogen, fifteen of carbonic acid gas that the water had not absorbed, and one of oxygen.) lastly, i set the wood and the roots of the mangrove thoroughly wetted, to act on a given volume of atmospheric air in a phial with a ground-glass stopple. the whole of the oxygen disappeared; and, far from being superseded by carbonic acid, lime-water indicated only . . there was even a diminution of the volume of air, more than correspondent with the oxygen absorbed. these slight experiments led me to conclude that it is the moistened bark and wood which act upon the atmosphere in the forests of mangrove-trees, and not the water strongly tinged with yellow, forming a distinct band along the coasts. in pursuing the different stages of the decomposition of the ligneous matter, i observed no appearance of a disengagement of sulphuretted hydrogen, to which many travellers attribute the smell perceived amidst mangroves. the decomposition of the earthy and alkaline sulphates, and their transition to the state of sulphurets, may no doubt favour this disengagement in many littoral and marine plants; for instance, in the fuci: but i am rather inclined to think that the rhizophora, the avicennia, and the conocarpus, augment the insalubrity of the air by the animal matter which they contain conjointly with tannin. these shrubs belong to the three natural families of the lorantheae, the combretaceae, and the pyrenaceae, in which the astringent principle abounds; this principle accompanies gelatin, even in the bark of beech, alder, and nut-trees. moreover, a thick wood spreading over marshy grounds would diffuse noxious exhalations in the atmosphere, even though that wood were composed of trees possessing in themselves no deleterious properties. wherever mangroves grow on the sea-shore, the beach is covered with infinite numbers of molluscs and insects. these animals love shade and faint light, and they find themselves sheltered from the shock of the waves amid the scaffolding of thick and intertwining roots, which rises like lattice-work above the surface of the waters. shell-fish cling to this lattice; crabs nestle in the hollow trunks; and the seaweeds, drifted to the coast by the winds and tides, remain suspended on the branches which incline towards the earth. thus, maritime forests, by the accumulation of a slimy mud between the roots of the trees, increase the extent of land. but whilst these forests gain on the sea, they do not enlarge their own dimensions; on the contrary, their progress is the cause of their destruction. mangroves, and other plants with which they live constantly in society, perish in proportion as the ground dries and they are no longer bathed with salt water. their old trunks, covered with shells, and half-buried in the sand, denote, after the lapse of ages, the path they have followed in their migrations, and the limits of the land which they have wrested from the ocean. the bay of higuerote is favourably situated for examining cape codera, which is there seen in its full extent seven miles distant. this promontory is more remarkable for its size than for its elevation, being only about two hundred toises high. it is perpendicular on the north-west and east. in these grand profiles the dip of the strata appears to be distinguishable. judging from the fragments of rock found along the coast, and from the hills near higuerote, cape codera is not composed of granite with a granular texture, but of a real gneiss with a foliated texture. its laminae are very broad and sometimes sinuous.* (* dickflasriger gneiss.) they contain large nodules of reddish feldspar and but little quartz. the mica is found in superposed lamellae, not isolated. the strata nearest the bay were in the direction of degrees north-east, and dipped degrees to north-west. these relations of direction and of dip are the same at the great mountain of the silla, near caracas, and to the east of maniquarez, in the isthmus of araya. they seem to prove that the primitive chain of that isthmus, after having been ruptured or swallowed up by the sea along a space of thirty-five leagues,* (* between the meridians of maniquarez and higuerote.) appears anew in cape codera, and continues westward as a chain of the coast. i was assured that, in the interior of the earth, south of higuerote, limestone formations are found. the gneiss did not act upon the magnetic needle; yet along the coast, which forms a cove near cape codera, and which is covered with a fine forest, i saw magnetic sand mixed with spangles of mica, deposited by the sea. this phenomenon occurs again near the port of la guayra. possibly it may denote the existence of some strata of hornblende-schist covered by the waters, in which schist the sand is disseminated. cape codera forms on the north an immense spherical segment. a shallow which stretches along its foot is known to navigators by the name of the points of tutumo and of san francisco. the road by land from higuerote to caracas, runs through a wild and humid tract of country, by the montana of capaya, north of caucagua, and the valley of rio guatira and guarenas. some of our fellow-travellers determined on taking this road, and m. bonpland also preferred it, notwithstanding the continual rains and the overflowing of the rivers. it afforded him the opportunity of making a rich collection of new plants.* (* bauhinia ferruginea, brownea racemosa, b ed. inga hymenaeifolia, i. curiepensis (which willdenouw has called by mistake i. caripensis), etc.) for my part, i continued alone with the guaiqueria pilot the voyage by sea; for i thought it hazardous to lose sight of the instruments which we were to make use of on the banks of the orinoco. we set sail at night-fall. the wind was unfavourable, and we doubled cape codera with difficulty. the surges were short, and often broke one upon another. the sea ran the higher, owing to the wind being contrary to the current, till after midnight. the general motion of the waters within the tropics towards the west is felt strongly on the coast during two-thirds of the year. in the months of september, october, and november, the current often flows eastward for fifteen or twenty days in succession; and vessels on their way from guayra to porto cabello have sometimes been unable to stem the current which runs from west to east, although they have had the wind astern. the cause of these anomalies is not yet discovered. the pilots think they are the effect of gales of wind from the north-west in the gulf of mexico. on the st of november, at sunrise, we were to the west of cape codera, opposite curuao. the coast is rocky and very elevated, the scenery at once wild and picturesque. we were sufficiently near land to distinguish scattered huts surrounded by cocoa-trees, and masses of vegetation, which stood out from the dark ground of the rocks. the mountains are everywhere perpendicular, and three or four thousand feet high; their sides cast broad and deep shadows upon the humid land, which stretches out to the sea, glowing with the freshest verdure. this shore produces most of those fruits of the hot regions, which are seen in such great abundance in the markets of the caracas. the fields cultivated with sugar-cane and maize, between camburi and niguatar, stretch through narrow valleys, looking like crevices or clefts in the rocks: and penetrated by the rays of the sun, then above the horizon, they presented the most singular contrasts of light and shade. the mountain of niguatar and the silla of caracas are the loftiest summits of this littoral chain. the first almost reaches the height of canigou; it seems as if the pyrenees or the alps, stripped of their snows, had risen from the bosom of the ocean; so much more stupendous do mountains appear when viewed for the first time from the sea. near caravalleda, the cultivated lands enlarge; we find hills with gentle declivities, and the vegetation rises to a great height. the sugar-cane is here cultivated, and the monks of la merced have a plantation with two hundred slaves. this spot was formerly extremely subject to fever; and it is said that the air has acquired salubrity since trees have been planted round a small lake, the emanations of which were dreaded, and which is now less exposed to the ardour of the sun. to the west of caravalleda, a wall of bare rock again projects forward in the direction of the sea, but it has little extent. after having passed it, we immediately discovered the pleasantly situated village of macuto; the black rocks of la guayra, studded with batteries rising in tiers one over another, and in the misty distance, cabo blanco, a long promontory with conical summits, and of dazzling whiteness. cocoa-trees border the shore, and give it, under that burning sky, an appearance of fertility. i landed in the port of la guayra, and the same evening made preparations for transporting my instruments to caracas. having been recommended not to sleep in the town, where the yellow fever had been raging only a few weeks previously, i fixed my lodging in a house on a little hill, above the village of maiquetia, a place more exposed to fresh winds than la guayra. i reached caracas on the st of november, four days sooner than m. bonpland, who, with the other travellers on the land journey, had suffered greatly from the rain and the inundations of the torrents, between capaya and curiepe. before proceeding further, i will here subjoin a description of la guayra, and the extraordinary road which leads from thence to the town of caracas, adding thereto all the observations made by m. bonpland and myself, in an excursion to cabo blanco about the end of january . la guayra is rather a roadstead than a port. the sea is constantly agitated, and ships suffer at once by the violence of the wind, the tideways, and the bad anchorage. the lading is taken in with difficulty, and the swell prevents the embarkation of mules here, as at new barcelona and porto cabello. the free mulattoes and negroes, who carry the cacao on board the ships, are a class of men remarkable for muscular strength. they wade up to their waists through the water; and it is remarkable that they are never attacked by the sharks, so common in this harbour. this fact seems connected with what i have often observed within the tropics, with respect to other classes of animals which live in society, for instance monkeys and crocodiles. in the missions of the orinoco, and on the banks of the river amazon, the indians, who catch monkeys to sell them, know very well that they can easily succeed in taming those which inhabit certain islands; while monkeys of the same species, caught on the neighbouring continent, die of terror or rage when they find themselves in the power of man. the crocodiles of one lake in the llanos are cowardly, and flee even when in the water; whilst those of another lake will attack with extreme intrepidity. it would be difficult to explain this difference of disposition and habits, by the mere aspect of the respective localities. the sharks of the port of la guayra seem to furnish an analogous example. they are dangerous and blood-thirsty at the island opposite the coast of caracas, at the roques, at bonayre, and at curassao; while they forbear to attack persons swimming in the ports of la guayra and santa martha. the natives, who like the ignorant mass of people in every country, in seeking the explanation of natural phenomena, always have recourse to the marvellous, affirm that in the ports just mentioned, a bishop gave his benediction to the sharks. the situation of la guayra is very singular, and can only be compared to that of santa cruz in teneriffe. the chain of mountains which separates the port from the high valley of caracas, descends almost directly into the sea; and the houses of the town are backed by a wall of steep rocks. there scarcely remains one hundred or one hundred and forty toises breadth of flat ground between the wall and the ocean. the town has six or eight thousand inhabitants, and contains only two streets, running parallel with each other east and west. it is commanded by the battery of cerro colorado; and its fortifications along the sea-shore are well disposed, and kept in repair. the aspect of this place has in it something solitary and gloomy; we seemed not to be on a continent, covered with vast forests, but on a rocky island, destitute of vegetation. with the exception of cabo blanco and the cocoa-trees of maiquetia, no view meets the eye but that of the horizon, the sea, and the azure vault of heaven. the heat is excessive during the day, and most frequently during the night. the climate of la guayra is justly considered to be hotter than that of cumana, porto cabello, and coro, because the sea-breeze is less felt, and the air is heated by the radiant caloric which the perpendicular rocks emit from the time the sun sets. the examination of the thermometric observations made during nine months at la guayra by an eminent physician, enabled me to compare the climate of this port, with those of cumana, of the havannah, and of vera cruz. this comparison is the more interesting, as it furnishes an inexhaustible subject of conversation in the spanish colonies, and among the mariners who frequent those latitudes. as nothing is more deceiving in such matters than the testimony of the senses, we can judge of the difference of climates only by numerical calculations. the four places of which we have been speaking are considered as the hottest on the shores of the new world. a comparison of them may serve to confirm what we have several times observed, that it is generally the duration of a high temperature, and not the excess of heat, or its absolute quantity, which occasions the sufferings of the inhabitants of the torrid zone. a series of thermometric observations shows, that la guayra is one of the hottest places on the earth; that the quantity of heat which it receives in the course of a year is a little greater than that felt at cumana; but that in the months of november, december, and january (at equal distance from the two passages of the sun through the zenith of the town), the atmosphere cools more at la guayra. may not this cooling, much slighter than that which is felt almost at the same time at vera cruz and at the havannah, be the effect of the more westerly position of la guayra? the aerial ocean, which appears to form only one mass, is agitated by currents, the limits of which are fixed by immutable laws; and its temperature is variously modified by the configuration of the lands and seas by which it is sustained. it may be subdivided into several basins, which overflow into each other, and of which the most agitated (for instance, that over the gulf of mexico, or between the sierra of santa martha and the gulf of darien) have a powerful influence on the refrigeration and the motion of the neighbouring columns of air. the north winds sometimes cause influxes and counter-currents in the south-west part of the caribbean sea, which seem, during particular months, to diminish the heat as far as terra firma. at the time of my abode at la guayra, the yellow fever, or calentura amarilla, had been known only two years; and the mortality it occasioned had not been very great, because the confluence of strangers on the coast of caracas was less considerable than at the havannah or vera cruz. a few individuals, even creoles and mulattoes, were sometimes carried off suddenly by certain irregular remittent fevers; which, from being complicated with bilious appearances, hemorrhages, and other symptoms equally alarming, appeared to have some analogy with the yellow fever. the victims of these maladies were generally men employed in the hard labour of cutting wood in the forests, for instance, in the neighbourhood of the little port of carupano, or the gulf of santa fe, west of cumana. their death often alarmed the unacclimated europeans, in towns usually regarded as peculiarly healthy; but the seeds of the sporadic malady were propagated no farther. on the coast of terra firma, the real typhus of america, which is known by the names vomito prieto (black vomit) and yellow fever, and which must be considered as a morbid affection sui generis, was known only at porto cabello, at carthagena, and at santa martha, where gastelbondo observed and described it in . the spaniards recently disembarked, and the inhabitants of the valley of caracas, were not then afraid to reside at la guayra. they complained only of the oppressive heat which prevailed during a great part of the year. if they exposed themselves to the immediate action of the sun, they dreaded at most only those attacks of inflammation of the skin or eyes, which are felt everywhere in the torrid zone, and are often accompanied by a febrile affection and congestion in the head. many individuals preferred the ardent but uniform climate of la guayra to the cool but extremely variable climate of caracas; and scarcely any mention was made of the insalubrity of the former port. since the year everything has changed. commerce being thrown open to other vessels besides those of the mother country, seamen born in colder parts of europe than spain, and consequently more susceptible to the climate of the torrid zone, began to frequent la guayra. the yellow fever broke out. north americans, seized with the typhus, were received in the spanish hospitals; and it was affirmed that they had imported the contagion, and that the disease had appeared on board a brig from philadelphia, even before the vessel had entered the roads of la guayra. the captain of the brig denied the fact; and asserted that, far from having introduced the malady, his crew had caught it in the port. we know from what happened at cadiz in , how difficult it is to elucidate facts, when their uncertainty serves to favour theories diametrically opposite one to another. the more enlightened inhabitants of caracas and la guayra, divided in opinion, like the physicians of europe and the united states, on the question of the contagion of yellow fever, cited the instance of the american vessel; some for the purpose of proving that the typhus had come from abroad, and others, to show that it had taken birth in the country itself. those who advocated the latter opinion, admitted that an extraordinary alteration had been caused in the constitution of the atmosphere by the overflowings of the rio de la guayra. this torrent, which in general is not ten inches deep, was swelled after sixty hours' rain in the mountains, in so extraordinary a manner, that it bore down trunks of trees and masses of rock of considerable size. during this flood the waters were from thirty to forty feet in breadth, and from eight to ten feet deep. it was supposed that, issuing from some subterranean basin, formed by successive infiltrations, they had flowed into the recently cleared arable lands. many houses were carried away by the torrent; and the inundation became the more dangerous for the stores, in consequence of the gate of the town, which could alone afford an outlet to the waters, being accidentally closed. it was necessary to make a breach in the wall on the sea-side. more than thirty persons perished, and the damage was computed at half a million of piastres. the stagnant water, which infected the stores, the cellars, and the dungeons of the public prison, no doubt diffused miasms in the air, which, as a predisposing cause, may have accelerated the development of the yellow fever; but i believe that the inundation of the rio de la guayra was no more the primary cause, than the overflowings of the guadalquivir, the xenil, and the gual-medina, were at seville, at ecija, and at malaga, the primary causes of the fatal epidemics of and . i examined with attention the bed of the torrent of la guayra; and found it to consist merely of a barren soil, blocks of mica-slate, and gneiss, containing pyrites detached from the sierra de avila, but nothing that could have had any effect in deteriorating the purity of the air. since the years and , at which periods there prevailed dreadful mortality at philadelphia, st. lucia, and st. domingo, the yellow fever has continued its ravages at la guayra. it has proved fatal not only to the troops newly arrived from spain, but also to those levied in parts remote from the coasts, in the llanos between calabozo and uritucu, regions almost as hot as la guayra, but favourable to health. this latter fact would seem more surprising, did we not know, that even the natives of vera cruz, who are not attacked with typhus in their own town, sometimes sink under it during the epidemics of the havannah and the united states. as the black vomit finds an insurmountable barrier at the encero (four hundred and seventy-six toises high), on the declivity of the mountains of mexico, in the direction of xalapa, where oaks begin to appear, and the climate begins to be cool and pleasant, so the yellow fever scarcely ever passes beyond the ridge of mountains which separates la guayra from the valley of caracas. this valley has been exempt from the malady for a considerable time; for we must not confound the vomito and the yellow fever with the irregular and bilious fevers. the cumbre and the cerro do avila form a very useful rampart to the town of caracas, the elevation of which a little exceeds that of the encero, but of which the mean temperature is above that of xalapa. i have published in another work* (* nouvelle espagne tome .) the observations made by m. bonpland and myself on the locality of the towns periodically subject to the visitation of yellow fever; and i shall not hazard here any new conjectures on the changes observed in the pathogenic constitution of particular localities. the more i reflect on this subject, the more mysterious appears to me all that relates to those gaseous emanations which we call so vaguely the seeds of contagion, and which are supposed to be developed by a corrupted air, destroyed by cold, conveyed from place to place in garments, and attached to the walls of houses. how can we explain why, for the space of eighteen years prior to , there was not a single instance of the vomito at vera cruz, though the concourse of unacclimated europeans and of mexicans from the interior, was very considerable; though sailors indulged in the same excesses with which they are still reproached; and though the town was not so clean as it has been since the year ? the following is the series of pathological facts, considered in their simplest point of view. when a great number of persons, born in a cold climate, arrive at the same period in a port of the torrid zone, not particularly dreaded by navigators, the typhus of america begins to appear. those persons have not had typhus during their passage; it appears among them only after they have landed. is the atmospheric constitution changed? or is it that a new form of disease develops itself among individuals whose susceptibility is highly increased? the typhus soon begins to extend its ravages among other europeans, born in more southern countries. if propagated by contagion, it seems surprising that in the towns of the equinoctial continent it does not attach itself to certain streets; and that immediate contact* does not augment the danger, any more than seclusion diminishes it. (* in the oriental plague (another form of typhus characterised by great disorder of the lymphatic system) immediate contact is less to be feared than is generally thought. larrey maintains that the tumified glands may be touched or cauterized without danger; but he thinks we ought not to risk putting on the clothes of persons attacked with the plague.--memoire sur les maladies de l'armee francoise en egypte page .) the sick, when removed to the inland country, and especially to cooler and more elevated spots, to xalapa, for instance, do not communicate typhus to the inhabitants of those places, either because the disease is not contagious in its nature, or because the predisposing causes are not the same as in the regions of the shore. when there is a considerable lowering of the temperature, the epidemic usually ceases, even on the spot where it first appeared. it again breaks out at the approach of the hot season, and sometimes long before; though during several months there may have been no sick person in the harbour, and no ship may have entered it. the typhus of america appears to be confined to the shore, either because persons who bring the disease disembark there, and goods supposed to be impregnated with deleterious miasms are there accumulated; or because on the sea-side gaseous emanations of a particular nature are formed. the aspect of the places subject to the ravages of typhus seems often to exclude all idea of a local or endemical origin. it has been known to prevail in the canaries, the bermudas, and among the small west india islands, in dry places formerly distinguished for the great salubrity of their climate. examples of the propagation of the yellow fever in the inland parts of the torrid zone appear very doubtful: that malady may have been confounded with remitting bilious fevers. with respect to the temperate zone, in which the contagious character of the american typhus is more decided, the disease has unquestionably spread far from the shore, even into very elevated places, exposed to cool and dry winds, as in spain at medina-sidonia, at carlotta, and in the city of murcia. that variety of phenomena which the same epidemic exhibits, according to the difference of climate, the union of predisposing causes, its shorter or longer duration, and the degree of its exacerbation, should render us extremely circumspect in tracing the secret causes of the american typhus. m. bailly, who, at the time of the violent epidemics in and , was chief physician to the colony of st. domingo, and who studied that disease in the island of cuba, the united states, and spain, is of opinion that the typhus is very often, but not always, contagious. since the yellow fever has made such ravages in la guayra, exaggerated accounts have been given of the uncleanliness in that little town as well as of vera cruz, and of the quays or wharfs of philadelphia. in a place where the soil is extremely dry, destitute of vegetation, and where scarcely a few drops of water fall in the course of seven or eight months, the causes that produce what are called miasms, cannot be of very frequent occurrence. la guayra appeared to me in general to be tolerably clean, with the exception of the quarter of the slaughter-houses. the sea-side has no beach on which the remains of fuci or molluscs are heaped up; but the neighbouring coast, which stretches eastward towards cape codera, and consequently to the windward of la guayra, is extremely unhealthy. intermitting, putrid, and bilious fevers often prevail at macuto and at caravalleda; and when from time to time the breeze is interrupted by a westerly wind, the little bay of cotia sends air loaded with putrid emanations towards the coast of la guayra, notwithstanding the rampart opposed by cabo blanco. the irritability of the organs being so different in the people of the north and those of the south, it cannot be doubted, that with greater freedom of commerce, and more frequent and intimate communication between countries situated in different climates, the yellow fever will extend its ravages in the new world. it is even probable that the concurrence of so many exciting causes, and their action on individuals so differently organized, may give birth to new forms of disease and new deviations of the vital powers. this is one of the evils that inevitably attend rising civilization. the yellow fever and the black vomit cease periodically at the havannah and vera cruz, when the north winds bring the cold air of canada towards the gulf of mexico. but from the extreme equality of temperature which characterizes the climates of porto cabello, la guayra, new barcelona, and cumana, it may be feared that the typhus will there become permanent, whenever, from a great influx of strangers, it has acquired a high degree of exacerbation. tracing the granitic coast of la guayra westward, we find between that port (which is in fact but an ill-sheltered roadstead) and that of porto cabello, several indentations of the land, furnishing excellent anchorage for ships. such are the small bay of catia, los arecifes, puerto-la-cruz, choroni, sienega de ocumare, turiamo, burburata, and patanebo. all these ports, with the exception of that of burburata, from which mules are exported to jamaica, are now frequented only by small coasting vessels, which are there laden with provisions and cacao from the surrounding plantations. the inhabitants of caracas are desirous to avail themselves of the anchorage of catia, to the west of cabo blanco. m. bonpland and myself examined that point of the coast during our second abode at la guayra. a ravine, called the quebrada de tipe, descends from the table-land of caracas towards catia. a plan has long been in contemplation for making a cart-road through this ravine and abandoning the old road to la guayra, which resembles the passage over st. gothard. according to this plan, the port of catia, equally large and secure, would supersede that of la guayra. unfortunately, however, all that shore, to leeward of cabo blanco, abounds with mangroves, and is extremely unhealthy. i ascended to the summit of the promontory, which forms cabo blanco, in order to observe the passage of the sun over the meridian. i wished to compare in the morning the altitudes taken with an artificial horizon and those taken with the horizon of the sea; to verify the apparent depression of the latter, by the barometrical measurement of the hill. by this method, hitherto very little employed, on reducing the heights of the sun to the same time, a reflecting instrument may be used like an instrument furnished with a level. i found the latitude of the cape to be degrees minutes seconds; i could only make use of the angles which gave the image of the sun reflected on a plane glass; the horizon of the sea was very misty, and the windings of the coast prevented me from taking the height of the sun on that horizon. the environs of cabo blanco are not uninteresting for the study of rocks. the gneiss here passes into the state of mica-slate (glimmerschiefer.), and contains, along the sea-coast, layers of schistose chlorite. (chloritschiefer.) in this latter i found garnets and magnetical sand. on the road to catia we see the chloritic schist passing into hornblende schist. (hornblendschiefer.) all these formations are found together in the primitive mountains of the old world, especially in the north of europe. the sea at the foot of cabo blanco throws up on the beach rolled fragments of a rock, which is a granular mixture of hornblende and lamellar feldspar. it is what is rather vaguely called primitive grunstein. in it we can recognize traces of quartz and pyrites. submarine rocks probably exist near the coast, which furnish these very hard masses. i have compared them in my journal to the paterlestein of fichtelberg, in franconia, which is also a diabase, but so fusible, that glass buttons are made of it, which are employed in the slave-trade on the coast of guinea. i believed at first, according to the analogy of the phenomena furnished by the mountains of franconia, that the presence of these hornblende masses with crystals of common (uncompact) feldspar indicated the proximity of transition rocks; but in the high valley of caracas, near antimano, balls of the same diabase fill a vein crossing the mica-slate. on the western declivity of the hill of cabo blanco, the gneiss is covered with a formation of sandstone, or conglomerate, extremely recent. this sandstone combines angular fragments of gneiss, quartz, and chlorite, magnetical sand, madrepores, and petrified bivalve shells. is this formation of the same date as that of punta araya and cumana? scarcely any part of the coast has so burning a climate as the environs of cabo blanco. we suffered much from the heat, augmented by the reverberation of a barren and dusty soil; but without feeling any bad consequences from the effects of insolation. the powerful action of the sun on the cerebral functions is extremely dreaded at la guayra, especially at the period when the yellow fever begins to be felt. being one day on the terrace of the house, observing at noon the difference of the thermometer in the sun and in the shade, a man approached me holding in his hand a potion, which he conjured me to swallow. he was a physician, who from his window, had observed me bareheaded, and exposed to the rays of the sun. he assured me, that, being a native of a very northern climate, i should infallibly, after the imprudence i had committed, be attacked with the yellow fever that very evening, if i refused to take the remedy against it. i was not alarmed by this prediction, however serious, believing myself to have been long acclimated; but i could not resist yielding to entreaties, prompted by such benevolent feelings. i swallowed the dose; and the physician doubtless counted me among the number of those he had saved. the road leading from the port to caracas (the capital of a government of near , inhabitants) resembles, as i have already observed, the passage over the alps, the road of st. gothard, and of the great st. bernard. taking the level of the road had never been attempted before my arrival in the province of venezuela. no precise idea had even been formed of the elevation of the valley of caracas. it had indeed been long observed, that the descent was much less from la cumbre and las vueltas (the latter is the culminating point of the road towards the pastora at the entrance of the valley of caracas), than towards the port of la guayra; but the mountain of avila having a very considerable bulk, the eye cannot discern simultaneously the points to be compared. it is even impossible to form a precise idea of the elevation of caracas, from the climate of the valley, where the atmosphere is cooled by the descending currents of air, and by the mists, which envelope the lofty summit of the silla during a great part of the year. when in the season of the great heats we breathe the burning atmosphere of la guayra, and turn our eyes towards the mountains, it seems scarcely possible that, at the distance of five or six thousand toises, a population of forty thousand individuals assembled in a narrow valley, enjoys the coolness of spring, a temperature which at night descends to degrees of the centesimal thermometer. this near approach of different climates is common in the cordillera of the andes; but everywhere, at mexico, at quito, in peru, and in new granada, it is only after a long journey into the interior, either across plains or along rivers, that we reach the great cities, which are the central points of civilization. the height of caracas is but a third of that of mexico, quito, and santa fe de bogota; yet of all the capitals of spanish america which enjoy a cool and delicious climate in the midst of the torrid zone, caracas is nearest to the coast. what a privilege for a city to possess a seaport at three leagues distance, and to be situated among mountains, on a table-land, which would produce wheat, if the cultivation of the coffee-tree were not preferred! the road from la guayra to the valley of caracas is infinitely finer than the road from honda to santa fe, or that from guayaquil to quito. it is kept in better order than the old road, which led from the port of vera cruz to perote, on the eastern declivity of the mountains of new spain. with good mules it takes but three hours to go from the port of la guayra to caracas; and only two hours to return. with loaded mules, or on foot, the journey is from four to five hours. the road runs along a ridge of rocks extremely steep, and after passing the stations bearing respectively the names of torre quemada, curucuti, and salto, we arrive at a large inn (la venta) built at six hundred toises above the level of the sea. the name torre quemada, or burnt tower, indicates the sensation that is felt in descending towards la guayra. a suffocating heat is reflected from the walls of rock, and especially from the barren plains on which the traveller looks down. on this road, as on that from vera cruz to mexico, and wherever on a rapid declivity the climate changes, the increase of muscular strength and the sensation of well-being, which we experience as we advance into strata of cooler air, have always appeared to me less striking than the feeling of languor and debility which pervades the frame, when we descend towards the burning plains of the coast. but such is the organization of man; and even in the moral world, we are less soothed by that which ameliorates our condition than annoyed by a new sensation of discomfort. from curucuti to salto the ascent is somewhat less laborious. the sinuosities of the way render the declivity easier, as in the old road over mont cenis. the salto (or leap) is a crevice, which is crossed by a draw-bridge. fortifications crown the summit of the mountain. at la venta the thermometer at noon stood at . degrees, when at la guayra it kept up at the same hour at . degrees. la venta enjoys some celebrity in europe and in the united states, for the beauty of its surrounding scenery. when the clouds permit, this spot affords a magnificent view of the sea, and the neighbouring coasts. an horizon of more than twenty-two leagues radius is visible; the white and barren shore reflects a dazzling mass of light; and the spectator beholds at his feet cabo blanco, the village of maiquetia with its cocoa-trees, la guayra, and the vessels in the port. but i found this view far more extraordinary, when the sky was not serene, and when trains of clouds, strongly illumined on their upper surface, seemed projected like floating islands on the ocean. strata of vapour, hovering at different heights, formed intermediary spaces between the eye and the lower regions. by an illusion easily explained, they enlarged the scene, and rendered it more majestic. trees and dwellings appeared at intervals through the openings, which were left by the clouds when driven on by the winds, and rolling over one another. objects then appear at a greater depth than when seen through a pure and uniformly serene air. on the declivity of the mountains of mexico, at the same height (between las trancas and xalapa), the sea is twelve leagues distant, and the view of the coast is confused; while on the road from la guayra to caracas we command the plains (the tierra caliente), as from the top of a tower. how extraordinary must be the impression created by this prospect on natives of the inland parts of the country, who behold the sea and ships for the first time from this point. i determined by direct observations the latitude of la venta, that i might be enabled to give a more precise idea of the distance of the coasts. the latitude is degrees minutes seconds. its longitude appeared to me by the chronometer, nearly minutes seconds west of the town of caracas. i found the dip of the needle at this height to be . degrees, and the intensity of the magnetic forces equal to two hundred and thirty-four oscillations. from the venta, called also la venta grande, to distinguish it from three or four small inns formerly established along the road, but now destroyed, there is still an ascent of one hundred and fifty toises to guayavo. this is nearly the most lofty point of the road. whether we gaze on the distant horizon of the sea, or turn our eyes south-eastward, in the direction of the serrated ridge of rocks, which seems to unite the cumbre and the silla, though separated from them by the ravine (quebrada) of tocume, everywhere we admire the grand character of the landscape. from guayavo we proceed for half an hour over a smooth table-land, covered with alpine plants. this part of the way, on account of its windings, is called las vueltas. we find a little higher up the barracks or magazines of flour, which were constructed in a spot of cool temperature by the guipuzcoa company, when they had the exclusive monopoly of the trade of caracas, and supplied that place with provision. on the road to las vueltas we see for the first time the capital, situated three hundred toises below, in a valley luxuriantly planted with coffee and european fruit-trees. travellers are accustomed to halt near a fine spring, known by the name of fuente de sanchorquiz, which flows down from the sierra on sloping strata of gneiss. i found its temperature . degrees; which, for an elevation of seven hundred and twenty-six toises, is considerably cool, and it would appear much cooler to those who drink its limpid water, if, instead of gushing out between la cumbre and the temperate valley of caracas, it were found on the descent towards la guayra. but at this descent on the northern side of the mountain, the rock, by an uncommon exception in this country, does not dip to north-west, but to south-east, which prevents the subterranean waters from forming springs there. we continued to descend from the small ravine of sanchorquiz to la cruz de la guayra, a cross erected on an open spot, six hundred and thirty-two toises high, and thence (entering by the custom-house and the quarter of the pastora) to the city of caracas. on the south side of the mountain of avila, the gneiss presents several geognostical phenomena worthy of the attention of travellers. it is traversed by veins of quartz, containing cannulated and often articulated prisms of rutile titanite two or three lines in diameter. in the fissures of the quartz we find, on breaking it, very thin crystals, which crossing each other form a kind of network. sometimes the red schorl occurs only in dendritic crystals of a bright red.* (* especially below the cross of la guayra, at toises of absolute elevation.) the gneiss of the valley of caracas is characterized by the red and green garnets it contains; they however disappear when the rock passes into mica-slate. this same phenomenon has been remarked by von buch in sweden; but in the temperate parts of europe garnets are in general contained in serpentine and mica-slates, not in gneiss. in the walls which enclose the gardens of caracas, constructed partly of fragments of gneiss, we find garnets of a very fine red, a little transparent, and very difficult to detach. the gneiss near the cross of la guayra, half a league from caracas, presented also vestiges of azure copper-ore* (* blue carbonate of copper.) disseminated in veins of quartz, and small strata of plumbago (black lead), or earthy carburetted iron. this last is found in pretty large masses, and sometimes mingled with sparry iron-ore, in the ravine of tocume, to the west of the silla. between the spring of sanchorquiz and the cross of la guayra, as well as still higher up, the gneiss contains considerable beds of saccharoidal bluish-grey primitive limestone, coarse-grained, containing mica, and traversed by veins of white calcareous spar. the mica, with large folia, lies in the direction of the dip of the strata. i found in the primitive limestone a great many crystallized pyrites, and rhomboidal fragments of sparry iron-ore of isabella yellow. i endeavoured, but without success, to find tremolite (grammatite of hauy. the primitive limestone above the spring of sanchorquiz, is directed, as the gneiss in that place, hor. . , and dips degrees north; but the general direction of the gneiss is, in the cerro de avila, hor. . with degrees of dip north-west. exceptions merely local are observed in a small space of ground near the cross of la guayra (hor. . , dip degrees north); and higher up, opposite the quebrada of tipe (hor. , dip degrees west).), which in the fichtelberg, in franconia, is common in the primitive limestone without dolomite. in europe beds of primitive limestone are generally observed in the mica-slates; but we find also saccharoidal limestone in gneiss of the most ancient formation, in sweden near upsala, in saxony near burkersdorf, and in the alps in the road over the simplon. these situations are analogous to that of caracas. the phenomena of geognosy, particularly those which are connected with the stratification of rocks, and their grouping, are never solitary; but are found the same in both hemispheres. i was the more struck with these relations, and this identity of formations, as, at the time of my journey in these countries, mineralogists were unacquainted with the name of a single rock of venezuela, new grenada, and the cordilleras of quito. chapter . . general view of the provinces of venezuela. diversity of their interests. city and valley of caracas. climate. in all those parts of spanish america in which civilization did not exist to a certain degree before the conquest (as it did in mexico, guatimala, quito, and peru), it has advanced from the coasts to the interior of the country, following sometimes the valley of a great river, sometimes a chain of mountains, affording a temperate climate. concentrated at once in different points, it has spread as if by diverging rays. the union into provinces and kingdoms was effected on the first immediate contact between civilized parts, or at least those subject to permanent and regular government. lands deserted, or inhabited by savage tribes, now surround the countries which european civilization has subdued. they divide its conquests like arms of the sea difficult to be passed, and neighbouring states are often connected with each other only by slips of cultivated land. it is less difficult to acquire a knowledge of the configuration of coasts washed by the ocean, than of the sinuosities of that interior shore, on which barbarism and civilization, impenetrable forests and cultivated land, touch and bound each other. from not having reflected on the early state of society in the new world, geographers have often made their maps incorrect, by marking the different parts of the spanish and portuguese colonies, as though they were contiguous at every point in the interior. the local knowledge which i obtained respecting these boundaries, enables me to fix the extent of the great territorial divisions with some certainty, to compare the wild and inhabited parts, and to appreciate the degree of political influence exercised by certain towns of america, as centres of power and of commerce. caracas is the capital of a country nearly twice as large as peru, and now little inferior in extent to the kingdom of new grenada.* (* the capitania-general of caracas contains near , square leagues (twenty-five to a degree). peru, since la paz, potosi, charcas and santa cruz de la sierra, have been separated from it, contains only , . new grenada, including the province of quito, contains , . reinos, capitanias-generales, presidencies, goviernos, and provincias, are the names by which spain formerly distinguished her transmarine possessions, or, as they were called, dominios de ultramar (dominions beyond sea.)) this country which the spanish government designates by the name of capitania-general de caracas,* (* the captain-general of caracas has the title of "capitan-general de las provincias de venezuela y ciudad do caracas.") or of the united provinces of venezuela, has nearly a million of inhabitants, among whom are sixty thousand slaves. it comprises, along the coasts, new andalusia, or the province of cumana (with the island of margareta),* (* this island, near the coast of cumana, forms a separate govierno, depending immediately on the captain-general of caracas.) barcelona, venezuela or caracas, coro, and maracaybo; in the interior, the provinces of varinas and guiana; the former situated on the rivers of santo domingo and the apure, the latter stretching along the orinoco, the casiquiare, the atabapo, and the rio negro. in a general view of the seven united provinces of terra firma, we perceive that they form three distinct zones, extending from east to west. we find, first, cultivated land along the sea-shore, and near the chain of the mountains on the coast; next, savannahs or pasturages; and finally, beyond the orinoco, a third zone, that of the forests, into which we can penetrate only by the rivers which traverse them. if the native inhabitants of the forests lived entirely on the produce of the chase, like those of the missouri, we might say that the three zones into which we have divided the territory of venezuela, picture the three states of human society; the life of the wild hunter, in the woods of the orinoco; pastoral life, in the savannahs or llanos; and the agricultural state, in the high valleys, and at the foot of the mountains on the coast. missionary monks and some few soldiers occupy here, as throughout all spanish america, advanced posts along the frontiers of brazil. in this first zone are felt the preponderance of force, and the abuse of power, which is its necessary consequence. the natives carry on civil war, and sometimes devour one another. the monks endeavour to augment the number of little villages of their missions, by taking advantage of the dissensions of the natives. the military live in a state of hostility to the monks, whom they were intended to protect. everything presents a melancholy picture of misery and privation. we shall soon have occasion to examine more closely that state of man, which is vaunted as a state of nature, by those who inhabit towns. in the second region, in the plains and pasture-grounds, food is extremely abundant, but has little variety. although more advanced in civilization, the people beyond the circle of some scattered towns are not less isolated from one another. at sight of their dwellings, partly covered with skins and leather, it might be supposed that, far from being fixed, they are scarcely encamped in those vast plains which extend to the horizon. agriculture, which alone consolidates the bases, and strengthens the bonds of society, occupies the third zone, the shore, and especially the hot and temperate valleys among the mountains near the sea. it may be objected, that in other parts of spanish and portuguese america, wherever we can trace the progressive development of civilization, we find the three ages of society combined. but it must be remembered that the position of the three zones, that of the forests, the pastures, and the cultivated land, is not everywhere the same, and that it is nowhere so regular as in venezuela. it is not always from the coast to the interior, that population, commercial industry, and intellectual improvement, diminish. in mexico, peru, and quito, the table-lands and central mountains possess the greatest number of cultivators, the most numerous towns situated near to each other, and the most ancient institutions. we even find, that, in the kingdom of buenos ayres, the region of pasturage, known by the name of the pampas, lies between the isolated part of buenos ayres and the great mass of indian cultivators, who inhabit the cordilleras of charcas, la paz, and potosi. this circumstance gives birth to a diversity of interests, in the same country, between the people of the interior and those who inhabit the coasts. to form an accurate idea of those vast provinces which have been governed for ages, almost like separate states, by viceroys and captains-general, we must fix our attention at once on several points. we must distinguish the parts of spanish america opposite to asia from those on the shores of the atlantic; we must ascertain where the greater portion of the population is placed; whether near the coast, or concentrated in the interior, on the cold and temperate table-lands of the cordilleras. we must verify the numerical proportions between the natives and other castes; search into the origin of the european families, and examine to what race, in each part of the colonies, belongs the greater number of whites. the andalusian-canarians of venezuela, the mountaineers* (* montaneses. the inhabitants of the mountains of santander are called by this name in spain.) and the biscayans of mexico, the catalonians of buenos ayres, differ essentially in their aptitude for agriculture, for the mechanical arts, for commerce, and for all objects connected with intellectual development. each of those races has preserved, in the new as in the old world, the shades that constitute its national physiognomy; its asperity or mildness of character; its freedom from sordid feelings, or its excessive love of gain; its social hospitality, or its taste for solitude. in the countries where the population is for the most part composed of indians and mixed races, the difference between the europeans and their descendants cannot indeed be so strongly marked, as that which existed anciently in the colonies of ionian and doric origin. the spaniards transplanted to the torrid zone, estranged from the habits of their mother-country, must have felt more sensible changes than the greeks settled on the coasts of asia minor, and of italy, where the climates differ so little from those of athens and corinth. it cannot be denied that the character of the spanish americans has been variously modified by the physical nature of the country; the isolated sites of the capitals on the table-lands or in the vicinity of the coasts; the agricultural life; the labour of the mines, and the habit of commercial speculation: but in the inhabitants of caracas, santa fe, quito, and buenos ayres, we recognize everywhere something which belongs to the race and the filiation of the people. if we examine the state of the capitania-general of caracas, according to the principles here laid down, we perceive that agricultural industry, the great mass of population, the numerous towns, and everything connected with advanced civilization, are found near the coast. this coast extends along a space of two hundred leagues. it is washed by the caribbean sea, a sort of mediterranean, on the shores of which almost all the nations of europe have founded colonies; which communicates at several points with the atlantic; and which has had a considerable influence on the progress of knowledge in the eastern part of equinoctial america, from the time of the conquest. the kingdoms of new grenada and mexico have no connection with foreign colonies, and through them with the nations of europe, except by the ports of carthagena, of santa martha, of vera cruz, and of campeachy. these vast countries, from the nature of their coasts, and the isolation of their inhabitants on the back of the cordilleras, have few points of contact with foreign lands. the gulf of mexico also is but little frequented during a part of the year, on account of the danger of gales of wind from the north. the coasts of venezuela, on the contrary, from their extent, their eastward direction, the number of their ports, and the safety of their anchorage at different seasons, possess all the advantages of the caribbean sea. the communications with the larger islands, and even with those situated to windward, can nowhere be more frequent than from the ports of cumana, barcelona, la guayra, porto cabello, coro, and maracaybo. can we wonder that this facility of commercial intercourse with the inhabitants of free america, and the agitated nations of europe, should in the provinces united under the capitania-general of venezuela, have augmented opulence, knowledge, and that restless desire of a local government, which is blended with the love of liberty and republican forms? the copper-coloured natives, or indians, constitute an important mass of the agricultural population only in those places where the spaniards, at the time of the conquest, found regular governments, social communities, and ancient and very complicated institutions; as, for example, in new spain, south of durango; and in peru, from cuzco to potosi. in the capitania-general of caracas, the indian population is inconsiderable, at least beyond the missions and in the cultivated zone. even in times of great political excitement, the natives do not inspire any apprehension in the whites or the mixed castes. computing, in , the total population of the seven united provinces at nine hundred thousand souls, it appeared to me that the indians made only one-ninth; while at mexico they form nearly one half of the inhabitants. considering the caribbean sea, of which the gulf of mexico makes a part, as an interior sea with several mouths, it is important to fix our attention on the political relations arising out of this singular configuration of the new continent, between countries placed around the same basin. notwithstanding the isolated state in which most of the mother-countries endeavour to hold their colonies, the agitations that take place are not the less communicated from one to the other. the elements of discord are everywhere the same; and, as if by instinct, an understanding is established between men of the same colour, although separated by difference of language, and inhabiting opposite coasts. that american mediterranean formed by the shores of venezuela, new grenada, mexico, the united states, and the west india islands, counts upon its borders near a million and a half of free and enslaved blacks; but so unequally distributed, that there are very few to the south, and scarcely any in the regions of the west. their great accumulation is on the northern and eastern coasts, which may be said to be the african part of the interior basin. the commotions which since have broken out in st. domingo, have naturally been propagated to the coasts of venezuela. so long as spain possessed those fine colonies in tranquillity, the little insurrections of the slaves were easily repressed; but when a struggle of another kind, that for independence, began, the blacks by their menacing position excited alternately the apprehensions of the opposite parties; and the gradual or instantaneous abolition of slavery has been proclaimed in different regions of spanish america, less from motives of justice and humanity, than to secure the aid of an intrepid race of men, habituated to privation, and fighting for their own cause. i found in the narrative of the voyage of girolamo benzoni, a curious passage, which proves that the apprehensions caused by the increase of the black population are of very old date. these apprehensions will cease only where governments shall second by laws the progressive reforms which refinement of manners, opinion, and religious sentiment, introduce into domestic slavery. "the negroes," says benzoni, "multiply so much at st. domingo, that in , when i was in terra firma [on the coast of caracas], i saw many spaniards who had no doubt that the island would shortly be the property of the blacks."* (* "vi sono molti spagnuoli che tengono per cosa certa, che quest' isola (san dominico) in breve tempo sara posseduta da questi mori di guinea." (benzoni istoria del mondo nuovo ediz. da page .) the author, who is not very scrupulous in the adoption of statistical facts, believes that in his time there were at st. domingo seven thousand fugitive negroes (mori cimaroni), with whom don luis columbus made a treaty of peace and friendship.) it was reserved for our age to see this prediction accomplished; and a european colony of america transform itself into an african state. the sixty thousand slaves which the seven united provinces of venezuela are computed to contain, are so unequally divided, that in the province of caracas alone there are nearly forty thousand, one-fifth of whom are mulattoes; in maracaybo, there are ten or twelve thousand; but in cumana and barcelona, scarcely six thousand. to judge of the influence which the slaves and men of colour exercise on the public tranquility, it is not enough to know their number, we must consider their accumulation at certain points, and their manner of life, as cultivators or inhabitants of towns. in the province of venezuela, the slaves are assembled together on a space of no great extent, between the coast, and a line which passes (at twelve leagues from the coast) through panaquire, yare, sabana de ocumare, villa de cura, and nirgua. the llanos or vast plains of calaboso, san carlos, guanare, and barquecimeto, contain only four or five thousand slaves, who are scattered among the farms, and employed in the care of cattle. the number of free men is very considerable; the spanish laws and customs being favourable to affranchisement. a master cannot refuse liberty to a slave who offers him the sum of three hundred piastres, even though the slave may have cost double that price, on account of his industry, or a particular aptitude for the trade he practises. instances of persons who voluntarily bestow liberty on a certain number of their slaves, are more common in the province of venezuela than in any other place. a short time before we visited the fertile valleys of aragua and the lake of valencia, a lady who inhabited the great village of victoria, ordered her children, on her death-bed, to give liberty to all her slaves, thirty in number. i feel pleasure in recording facts that do honour to the character of a people from whom m. bonpland and myself received so many marks of kindness. if we compare the seven united provinces of venezuela with the kingdom of mexico and the island of cuba, we shall succeed in finding the approximate number of white creoles, and even of europeans. the white creoles, whom i may call hispano-americans,* (* in imitation of the word anglo-american, adapted in all the languages of europe. in the spanish colonies, the whites born in america are called spaniards; and the real spaniards, those born in the mother country, are called europeans, gachupins, or chapetons.) form in mexico nearly a fifth, and in the island of cuba, according to the very accurate enumeration of , a third of the whole population. when we reflect that the kingdom of mexico contains two millions and a half of natives of the copper-coloured race; when we consider the state of the coasts bordering on the pacific, and the small number of whites in the intendencias of puebla and oaxaca, compared with the natives, we cannot doubt that the province of venezuela at least, if not the capitania-general, has a greater proportion than that of one to five. the island of cuba,* (* i do not mention the kingdom of buenos ayres, where, among a million of inhabitants, the whites are extremely numerous in parts near the coast; while the table-lands, or provinces of the sierra are almost entirely peopled with natives.) in which the whites are even more numerous than in chile, may furnish us with a limiting number, that is to say, the maximum which may be supposed in the capitania-general of caracas. i believe we must stop at two hundred, or two hundred and ten thousand hispano-americans, in a total population of nine hundred thousand souls. the number of europeans included in the white race (not comprehending the troops sent from the mother-country) does not exceed twelve or fifteen thousand. it certainly is not greater at mexico than sixty thousand; and i find by several statements, that, if we estimate the whole of the spanish colonies at fourteen or fifteen millions of inhabitants, there are in that number at most three millions of creole whites, and two hundred thousand europeans. when tupac-amaru, who believed himself to be the legitimate heir to the empire of the incas, made the conquest of several provinces of upper peru, in , at the head of forty thousand indian mountaineers, all the whites were filled with alarm. the hispano-americans felt, like the spaniards born in europe, that the contest was between the copper-coloured race and the whites; between barbarism and civilization. tupac-amaru, who himself was not destitute of intellectual cultivation, began with flattering the creoles and the european clergy; but soon, impelled by events, and by the spirit of vengeance that inspired his nephew, andres condorcanqui, he changed his plan. a rising for independence became a cruel war between the different castes; the whites were victorious, and excited by a feeling of common interest, from that period they kept watchful attention on the proportions existing in the different provinces between their numbers and those of the indians. it was reserved for our times to see the whites direct this attention towards themselves; and examine, from motives of distrust, the elements of which their own caste is composed. every enterprise in favour of independence and liberty puts the national or american party in opposition to the men of the mother-country. when i arrived at caracas, the latter had just escaped from the danger with which they thought they were menaced by the insurrection projected by espana. the consequences of that bold attempt were the more deplorable, because, instead of investigating the real causes of the popular discontent, it was thought that the mother-country would be saved by employing vigorous measures. at present, the commotions which have arisen throughout the country, from the banks of the rio de la plata to new mexico, an extent of fourteen hundred leagues, have divided men of a common origin. the indian population in the united provinces of venezuela is not considerable, and is but recently civilized. all the towns were founded by the spanish conquerors, who could not carry out, as in mexico and peru, the old civilization of the natives. caracas, maracaybo, cumana, and coro, have nothing indian but their names. compared with the three capitals of equinoctial america,* (* mexico, santa fe de bogota, and quito. the elevation of the site of the capital of guatimala is still unknown. judging from the vegetation, we may infer that it is less than toises.) situated on the mountains, and enjoying a temperate climate, caracas is the least elevated. it is not a central point of commerce, like mexico, santa fe de bogota, and quito. each of the seven provinces united in one capitania-general has a port, by which its produce is exported. it is sufficient to consider the position of the provinces, their respective degree of intercourse with the windward islands, the direction of the mountains, and the course of the great rivers, to perceive that caracas can never exercise any powerful political influence over the territories of which it is the capital. the apure, the meta, and the orinoco, running from west to east, receive all the streams of the llanos, or the region of pasturage. st. thomas de la guiana will necessarily, at some future day, be a trading-place of high importance, especially when the flour of new grenada, embarked above the confluence of the rio negro and the umadea, and descending by the meta and orinoco, shall be preferred at caracas and guiana to the flour of new england. it is a great advantage to the provinces of venezuela, that their territorial wealth is not directed to one point, like that of mexico and new grenada, which flows to vera cruz and carthagena; but that they possess a great number of towns equally well peopled, and forming various centres of commerce and civilization. the city of caracas is seated at the entrance of the plain of chacao, which extends three leagues eastward, in the direction of caurimare and the cuesta de auyamas, and is two leagues and a half in breadth. this plain, through which runs the rio guayra, is at the elevation of four hundred and fourteen toises above the level of the sea. the ground on which the city of caracas is built is uneven, and has a steep slope from north-north-west to south-south-east. to form an accurate idea of the situation of caracas, we must bear in mind the general direction of the mountains of the coast, and the great longitudinal valleys by which they are traversed. the rio guayra rises in the group of primitive mountains of higuerote, which separates the valley of caracas from that of aragua. it is formed near las ajuntas, by the junction of the little rivers of san pedro and macarao, and runs first eastward as far as the cuesta of auyamas, and then southward, uniting its waters with those of the rio tuy, below yare. the rio tuy is the only considerable river in the northern and mountainous part of the province. the river flows in a direct course from west to east, the distance of thirty leagues, and it is navigable along more than three quarters of that distance. by barometrical measurements i found the slope of the tuy along this length, from the plantation of manterola* (* at the foot of the high mountain of cocuyza, east from victoria.) to its mouth, east of cape codera, to be two hundred and ninety-five toises. this river forms in the chain of the coast a kind of longitudinal valley, while the waters of the llanos, or of five-sixths of the province of caracas, follow the slope of the land southward, and join the orinoco. this hydrographic sketch may throw some light on the natural tendency of the inhabitants of each particular province, to export their productions by different roads. the valleys of caracas and of the tuy run parallel for a considerable length. they are separated by a mountainous tract, which is crossed in going from caracas to the high savannahs of ocumare, passing by la valle and salamanca. these savannahs themselves are beyond the tuy; and the valley of the tuy being a great deal lower than that of caracas, the descent is almost constantly from north to south. as cape codera, the silla, the cerro de avila between caracas and la guayra, and the mountains of mariara, constitute the most northern and elevated range of the coast chain; so the mountains of panaquire, ocumare, guiripa, and of the villa de cura, form the most southern range. the general direction of the strata composing this vast chain of the coast is from south-east to north-west; and the dip is generally towards north-west: hence it follows, that the direction of the primitive strata is independent of that of the whole chain. it is extremely remarkable, tracing this chain* from porto cabello as far as maniquarez and macanao, in the island of margareta (* i have spoken, in the preceding chapter, of the interruption in the chain of the coast to the east of cape codera.), to find, from west to east, first granite, then gneiss, mica-slate, and primitive schist; and finally, compact limestone, gypsum, and conglomerates containing sea-shells. it is to be regretted that the town of caracas was not built farther to the east, below the entrance of the anauco into the guayra; on that spot near chacao, where the valley widens into an extensive plain, which seems to have been levelled by the waters. diego de losada, when he founded* the town, followed no doubt the traces of the first establishment made by faxardo. at that time, the spaniards, attracted by the high repute of the two gold mines of los teques and baruta, were not yet masters of the whole valley, and preferred remaining near the road leading to the coast. (* the foundation of santiago de leon de caracas dates from , and is posterior to that of cumana, coro, nueva barcelona, and caravalleda, or el collado.) the town of quito is also built in the narrowest and most uneven part of a valley, between two fine plains, turupamba and rumipamba. the descent is uninterrupted from the custom-house of the pastora, by the square of trinidad and the plaza mayor, to santa rosalia, and the rio guayra. this declivity of the ground does not prevent carriages from going about the town; but the inhabitants make little use of them. three small rivers, descending from the mountains, the anauco, the catuche, and the caraguata, intersect the town, running from north to south. their banks are very high; and, with the dried-up ravines which join them, furrowing the ground, they remind the traveller of the famous guaicos of quito, only on a smaller scale. the water used for drinking at caracas is that of the rio catuche; but the richer class of the inhabitants have their water brought from la valle, a village a league distant on the south. this water and that of gamboa are considered very salubrious, because they flow over the roots of sarsaparilla.* (* throughout america water is supposed to share the properties of those plants under the shade of which it flows. thus, at the straits of magellan, that water is much praised which comes in contact with the roots of the canella winterana.) i could not discover in them any aromatic or extractive matter. the water of the valley does not contain lime, but a little more carbonic acid than the water of the anauco. the new bridge over this river is a handsome structure. caracas contains eight churches, five convents, and a theatre capable of holding fifteen or eighteen hundred persons. when i was there, the pit, in which the seats of the men are apart from those of the women, was uncovered. by this means the spectators could either look at the actors or gaze at the stars. as the misty weather made me lose a great many observations of jupiter's satellites, i was able to ascertain, as i sat in a box in the theatre, whether the planet would be visible that night. the streets of caracas are wide and straight, and they cross each other at right angles, as in all the towns built by the spaniards in america. the houses are spacious, and higher than they ought to be in a country subject to earthquakes. in , the two squares of alta gracia and san francisco presented a very agreeable aspect; i say in the year , because the terrible shocks of the th of march, , almost destroyed the whole city, which is only now slowly rising from its ruins. the quarter of trinidad, in which i resided, was destroyed as completely as if a mine had been sprung beneath it. the small extent of the valley, and the proximity of the high mountains of avila and the silla, give a gloomy and stern character to the scenery of caracas; particularly in that part of the year when the coolest temperature prevails, namely, in the months of november and december. the mornings are then very fine; and on a clear and serene sky we could perceive the two domes or rounded pyramids of the silla, and the craggy ridge of the cerro de avila. but towards evening the atmosphere thickens; the mountains are overhung with clouds; streams of vapour cling to their evergreen slopes, and seem to divide them into zones one above another. these zones are gradually blended together; the cold air which descends from the silla, accumulates in the valley, and condenses the light vapours into large fleecy clouds. these often descend below the cross of la guayra, and advance, gliding on the soil, in the direction of the pastora of caracas, and the adjacent quarter of trinidad. beneath this misty sky, i could scarcely imagine myself to be in one of the temperate valleys of the torrid zone; but rather in the north of germany, among the pines and the larches that cover the mountains of the hartz. but this gloomy aspect, this contrast between the clearness of morning and the cloudy sky of evening, is not observable in the midst of summer. the nights of june and july are clear and delicious. the atmosphere then preserves, almost without interruption, the purity and transparency peculiar to the table-lands and elevated valleys of these regions in calm weather, as long as the winds do not mingle together strata of air of unequal temperature. that is the season for enjoying the beauty of the landscape, which, however, i saw clearly illumined only during a few days at the end of january. the two rounded summits of the silla are seen at caracas, almost under the same angles of elevation* as the peak of teneriffe at the port of orotava.* (* i found, at the square of trinidad, the apparent height of the silla to be degrees minutes seconds. it was about four thousand five hundred toises distant.) the first half of the mountain is covered with short grass; then succeeds the zone of evergreen trees, reflecting a purple light at the season when the befaria, the alpine rose-tree* (* rhododendron ferrugineum of the alps.) of equinoctial america, is in blossom. the rocky masses rise above this wooded zone in the form of domes. being destitute of vegetation, they increase by the nakedness of their surface the apparent height of a mountain which, in the temperate parts of europe, would scarcely rise to the limit of perpetual snow. the cultivated region of the valley, and the gay plains of chacao, petare, and la vega, form an agreeable contrast to the imposing aspect of the silla, and the great irregularities of the ground on the north of the town. the climate of caracas has often been called a perpetual spring. the same sort of climate exists everywhere, halfway up the cordilleras of equinoctial america, between four hundred and nine hundred toises of elevation, except in places where the great breadth of the valleys, combined with an arid soil, causes an extraordinary intensity* of radiant caloric. (* as at carthago and ibague in new grenada.) what can we conceive to be more delightful than a temperature which in the day keeps between and degrees (between and . degrees reaum.); and at night between and degrees (between . and . degrees reaum.), which is equally favourable to the plantain, the orange-tree, the coffee-tree, the apple, the apricot, and corn? jose de oviedo y banos, the historiographer of venezuela, calls the situation of caracas that of a terrestrial paradise, and compares the anauco and the neighbouring torrents to the four rivers of the garden of eden. it is to be regretted that this delightful climate is generally inconstant and variable. the inhabitants of caracas complain of having several seasons in one and the same day; and of the rapid change from one season to another. in the month of january, for instance, a night, of which the mean temperature is degrees, is sometimes followed by a day when the thermometer during eight successive hours keeps above degrees in the shade. in the same day, we may find the temperature of and degrees. these variations are extremely common in our temperate climates of europe, but in the torrid zone, europeans themselves are so accustomed to the uniform action of exterior stimulus, that they suffer from a change of temperature of degrees. at cumana, and everywhere in the plains, the temperature from eleven in the morning to eleven at night changes only or degrees. moreover, these variations act on the human frame at caracas more violently than might be supposed from the mere indications of the thermometer. in this narrow valley the atmosphere is in some sort balanced between two winds, one blowing from the west, or the seaside, the other from the east, or the inland country. the first is known by the name of the wind of catia, because it blows from catia westward of cabo blanco through the ravine of tipe. it is, however, only a westerly wind in appearance, and it is oftener the breeze of the east and north-east, which, rushing with extreme impetuosity, engulfs itself in the quebrada de tipe. rebounding from the high mountains of aguas negras, this wind finds its way back to caracas, in the direction of the hospital of the capuchins and the rio caraguata. it is loaded with vapours, which it deposits as its temperature decreases, and consequently the summit of the silla is enveloped in clouds, when the catia blows in the valley. this wind is dreaded by the inhabitants of caracas; it causes headache in persons whose nervous system is irritable. in order to shun its effects, people sometimes shut themselves up in their houses, as they do in italy when the sirocco is blowing. i thought i perceived, during my stay at caracas, that the wind of catia was purer (a little richer in oxygen) than the wind of petare. i even imagined that its purity might explain its exciting property. the wind of petare coming from the east and south-east, by the eastern extremity of the valley of the guayra, brings from the mountains and the interior of the country, a drier air, which dissipates the clouds, and the summit of the silla rises in all its beauty. we know that the modifications produced by winds in the composition of the air in various places, entirely escape our eudiometrical experiments, the most precise of which can estimate only as far as . degrees of oxygen. chemistry does not yet possess any means of distinguishing two jars of air, the one filled during the prevalence of the sirocco or the catia, and the other before these winds have commenced. it appears to me probable, that the singular effects of the catia, and of all those currents of air, to the influence of which popular opinion attaches so much importance, must be looked for rather in the changes of humidity and of temperature, than in chemical modifications. we need not trace miasms to caracas from the unhealthy shore on the coast: it may be easily conceived that men accustomed to the drier air of the mountains and the interior, must be disagreeably affected when the very humid air of the sea, pressed through the gap of tipe, reaches in an ascending current the high valley of caracas, and, getting cooler by dilatation, and by contact with the adjacent strata, deposits a great portion of the water it contains. this inconstancy of climate, these somewhat rapid transitions from dry and transparent to humid and misty air, are inconveniences which caracas shares in common with the whole temperate region of the tropics--with all places situated between four and eight hundred toises of elevation, either on table-lands of small extent, or on the slope of the cordilleras, as at xalapa in mexico, and guaduas in new granada. a serenity, uninterrupted during a great part of the year, prevails only in the low regions at the level of the sea, and at considerable heights on those vast table-lands, where the uniform radiation of the soil seems to contribute to the perfect dissolution of vesicular vapours. the intermediate zone is at the same height as the first strata of clouds which surround the surface of the earth; and the climate of this zone, the temperature of which is so mild, is essentially misty and variable. notwithstanding the elevation of the spot, the sky is generally less blue at caracas than at cumana. the aqueous vapour is less perfectly dissolved; and here, as in our climates, a greater diffusion of light diminishes the intensity of the aerial colour, by introducing white into the blue of the air. this intensity, measured with the cyanometer of saussure, was found from november to january generally , never above degrees. on the coasts it was from to degrees. i remarked, in the village of caracas, that the wind of petare sometimes contributes singularly to give a pale tint to the celestial vault. on the nd of january, the blue of the sky was at noon in the zenith feebler than i ever saw it in the torrid zone.* (* at noon, thermometer in the shade . (in the sun, out of the wind, . degrees); de luc's hygrometer, . ; cyanometer, at the zenith, , at the horizon degrees. the wind ceased at three in the afternoon. thermometer ; hygrometer . ; cyanometer degrees. at six o'clock, thermometer . ; hygrometer degrees.) it corresponded only to degrees of the cyanometer. the atmosphere was then remarkably transparent, without clouds, and of extraordinary dryness. the moment the wind of petare ceased, the blue colour rose at the zenith as high as degrees. i have often observed at sea, but in a smaller degree, a similar effect of the wind on the colour of the serenest sky. we know less exactly the mean temperature of caracas, than that of santa fe de bogota and of mexico. i believe, however, i can demonstrate, that it cannot be very distant from twenty to twenty-two degrees. i found by my own observations, during the three very cool months of november, december, and january, taking each day the maximum and minimum of the temperature, the heights were . ; . ; . degrees. rains are extremely frequent at caracas in the months of april, may, and june. the storms always come from the east and south-east, from the direction of petare and la valle. no hail falls in the low regions of the tropics; yet it occurs at caracas almost every four or five years. hail has even been seen in valleys still lower; and this phenomenon, when it does happen, makes a powerful impression on the people. falls of aerolites are less rare with us than hail in the torrid zone, notwithstanding the frequency of thunder-storms at the elevation of three hundred toises above the level of the sea. the cool and delightful climate we have just been describing is also suited for the culture of equinoctial productions. the sugar-cane is reared with success, even at heights exceeding that of caracas; but in the valley, owing to the dryness of the climate, and the stony soil, the cultivation of the coffee-tree is preferred: it yields indeed but little fruit, but that little is of the finest quality. when the shrub is in blossom, the plain extending beyond chacao presents a delightful aspect. the banana-tree, which is seen in the plantations near the town, is not the great platano harton; but the varieties camburi and dominico, which require less heat. the great plantains are brought to the market of caracas from the haciendas of turiamo, situated on the coast between burburata and porto cabello. the finest flavoured pine-apples are those of baruto, of empedrado, and of the heights of buenavista, on the road to victoria. when a traveller for the first time visits the valley of caracas, he is agreeably surprised to find the culinary plants of our climates, as well as the strawberry, the vine, and almost all the fruit-trees of the temperate zone, growing beside the coffee and banana-tree. the apples and peaches esteemed the best come from macarao, or from the western extremity of the valley. there, the quince-tree, the trunk of which attains only four or five feet in height, is so common, that it has almost become wild. preserved apples and quinces, particularly the latter,* (* "dulce de manzana y de membrillo," are the spanish names of these preserves.) are much used in a country where it is thought that, before drinking water, thirst should be excited by sweetmeats. in proportion as the environs of the town have been planted with coffee, and the establishment of plantations (which dates only from the year ) has increased the number of agricultural negroes,* the apple and quince-trees scattered in the savannahs have given place, in the valley of caracas, to maize and pulse. (* the consumption of provisions, especially meat, is so considerable in the towns of spanish america, that at caracas, in , there were , oxen killed every year: while in paris, in , with a population fourteen times as great, the number amounted only to , .) rice, watered by means of small trenches, was formerly more common than it now is in the plain of chacao. i observed in this province, as in mexico and in all the elevated lands of the torrid zone, that, where the apple-tree is most abundant, the culture of the pear-tree is attended with great difficulty. i have been assured, that near caracas the excellent apples sold in the markets come from trees not grafted. there are no cherry-trees. the olive-trees which i saw in the court of the convent of san felipe de neri, were large and fine; but the luxuriance of their vegetation prevented them from bearing fruit. if the atmospheric constitution of the valley be favourable to the different kinds of culture on which colonial industry is based, it is not equally favourable to the health of the inhabitants, or to that of foreigners settled in the capital of venezuela. the extreme inconstancy of the weather, and the frequent suppression of cutaneous perspiration, give birth to catarrhal affections, which assume the most various forms. a european, once accustomed to the violent heat, enjoys better health at cumana, in the valley of aragua, and in every place where the low region of the tropics is not very humid, than at caracas, and in those mountain-climates which are vaunted as the abode of perpetual spring. speaking of the yellow fever of la guayra, i mentioned the opinion generally adopted, that this disease is propagated as little from the coast of venezuela to the capital, as from the coast of mexico to xalapa. this opinion is founded on the experience of the last twenty years. the contagious disorders which were severely felt in the port of la guayra, were scarcely felt at caracas. i am not convinced that the american typhus, rendered endemic on the coast as the port becomes more frequented, if favoured by particular dispositions of the climate, may not become common in the valley: for the mean temperature of caracas is considerable enough to allow the thermometer, in the hottest months, to keep between twenty-two and twenty-six degrees. the situation of xalapa, on the declivity of the mexican mountains, promises more security, because that town is less populous, and is five times farther distant from the sea than caracas, and two hundred and thirty toises higher: its mean temperature being three degrees cooler. in , a bishop of venezuela, diego de banos, dedicated a church (ermita) to santa rosalia of palermo, for having delivered the capital from the scourge of the black vomit (vomito negro), which is said to have raged for the space of sixteen months. a mass celebrated every year in the cathedral, in the beginning of september, perpetuates the remembrance of this epidemic, in the same manner as processions fix, in the spanish colonies, the date of the great earthquakes. the year was indeed very remarkable for the yellow fever, which raged with violence in all the west india islands, where it had only begun to gain an ascendancy in . but how can we give credit to an epidemical black vomit, having lasted sixteen months without interruption, and which may be said to have passed through that very cool season when the thermometer at caracas falls to twelve or thirteen degrees? can the typhus be of older date in the elevated valley of caracas, than in the most frequented ports of terra firma. according to ulloa, it was unknown in terra firma before . i doubt, therefore, the epidemic of having been the yellow fever, or real typhus of america. some of the symptoms which accompany yellow fever are common to bilious remittent fevers; and are no more characteristic than haematemeses of that severe disease now known at the havannah and vera cruz by the name of vomito. but though no accurate description satisfactorily demonstrates that the typhus of america existed at caracas as early as the end of the seventeenth century, it is unhappily too certain, that this disease carried off in that capital a great number of european soldiers in . we are filled with dismay when we reflect that, in the centre of the torrid zone, a table-land four hundred and fifty toises high, but very near the sea, does not secure the inhabitants against a scourge which was believed to belong only to the low regions of the coast. chapter . . abode at caracas. mountains in the vicinity of the town. excursion to the summit of the silla. indications of mines. i remained two months at caracas, where m. bonpland and i lived in a large house in the most elevated part of the town. from a gallery we could survey at once the summit of the silla, the serrated ridge of the galipano, and the charming valley of the guayra, the rich culture of which was pleasingly contrasted with the gloomy curtain of the surrounding mountains. it was in the dry season, and to improve the pasturage, the savannahs and the turf covering the steepest rocks were set on fire. these vast conflagrations, viewed from a distance, produce the most singular effects of light. wherever the savannahs, following the undulating slope of the rocks, have filled up the furrows hollowed out by the waters, the flame appears in a dark night like currents of lava suspended over the valley. the vivid but steady light assumes a reddish tint, when the wind, descending from the silla, accumulates streams of vapour in the low regions. at other times (and this effect is still more curious) these luminous bands, enveloped in thick clouds, appear only at intervals where it is clear; and as the clouds ascend, their edges reflect a splendid light. these various phenomena, so common in the tropics, acquire additional interest from the form of the mountains, the direction of the slopes, and the height of the savannahs covered with alpine grasses. during the day, the wind of petare, blowing from the east, drives the smoke towards the town, and diminishes the transparency of the air. if we had reason to be satisfied with the situation of our house, we had still greater cause for satisfaction in the reception we met with from all classes of the inhabitants. though i have had the advantage, which few spaniards have shared with me, of having successively visited caracas, the havannah, santa fe de bogota, quito, lima, and mexico, and of having been connected in these six capitals of spanish america with men of all ranks, i will not venture to decide on the various degrees of civilization, which society has attained in the several colonies. it is easier to indicate the different shades of national improvement, and the point towards which intellectual development tends, than to compare and class things which cannot all be considered under one point of view. it appeared to me, that a strong tendency to the study of science prevailed at mexico and santa fe de bogota; more taste for literature, and whatever can charm an ardent and lively imagination, at quito and lima; more accurate notions of the political relations of countries, and more enlarged views on the state of colonies and their mother-countries, at the havannah and caracas. the numerous communications with commercial europe, with the caribbean sea (which we have described as a mediterranean with many outlets), have exercised a powerful influence on the progress of society in the five provinces of venezuela and in the island of cuba. in no other part of spanish america has civilization assumed a more european character. the great number of indian cultivators who inhabit mexico and the interior of new grenada, impart a peculiar, i may almost say, an exotic aspect, on those vast countries. notwithstanding the increase of the black population, we seem to be nearer to cadiz and the united states, at caracas and the havannah, than in any other part of the new world. when, in the reign of charles v, social distinctions and their consequent rivalries were introduced from the mother-country to the colonies, there arose in cumana and in other commercial towns of terra firma, exaggerated pretensions to nobility on the part of some of the most illustrious families of caracas, distinguished by the designation of los mantuanos. the progress of knowledge, and the consequent change in manners, have, however, gradually and pretty generally neutralized whatever is offensive in those distinctions among the whites. in all the spanish colonies there exist two kinds of nobility. one is composed of creoles, whose ancestors only from a very recent period filled great stations in america. their prerogatives are partly founded on the distinction they enjoy in the mother-country; and they imagine they can retain those distinctions beyond the sea, whatever may be the date of their settlement in the colonies. the other class of nobility has more of an american character. it is composed of the descendants of the conquistadores, that is to say, of the spaniards who served in the army at the time of the first conquest. among the warriors who fought with cortez, losada, and pizarro, several belonged to the most distinguished families of the peninsula; others, sprung from the inferior classes of the people, have shed lustre on their names, by that chivalrous spirit which prevailed at the beginning of the sixteenth century. in the records of those times of religious and military enthusiasm, we find, among the followers of the great captains, many simple, virtuous, and generous characters, who reprobated the cruelties which then stained the glory of the spanish name, but who, being confounded in the mass, have not escaped the general proscription. the name of conquistadares remains the more odious, as the greater number of them, after having outraged peaceful nations, and lived in opulence, did not end their career by suffering those misfortunes which appease the indignation of mankind, and sometimes soothe the severity of the historian. but it is not only the progress of ideas, and the conflict between two classes of different origin, which have induced the privileged castes to abandon their pretensions, or at least cautiously to conceal them. aristocracy in the spanish colonies has a counterpoise of another kind, the action of which becomes every day more powerful. a sentiment of equality, among the whites, has penetrated every bosom. wherever men of colour are either considered as slaves or as having been enfranchised, that which constitutes nobility is hereditary liberty--the proud boast of having never reckoned among ancestors any but freemen. in the colonies, the colour of the skin is the real badge of nobility. in mexico, as well as peru, at caracas as in the island of cuba, a bare-footed fellow with a white skin, is often heard to exclaim: "does that rich man think himself whiter than i am?" the population which europe pours into america being very considerable, it may easily be supposed, that the axiom, 'every white man is noble' (todo blanco es caballero), must singularly wound the pretensions of many ancient and illustrious european families. but it may be further observed, that the truth of this axiom has long since been acknowledged in spain, among a people justly celebrated for probity, industry, and national spirit. every biscayan calls himself noble; and there being a greater number of biscayans in america and the philippine islands, than in the peninsula, the whites of that race have contributed, in no small degree, to propagate in the colonies the system of equality among all men whose blood has not been mixed with that of the african race. moreover, the countries of which the inhabitants, even without a representative government, or any institution of peerage, annex so much importance to genealogy and the advantages of birth, are not always those in which family aristocracy is most offensive. we do not find among the natives of spanish origin, that cold and assuming air which the character of modern civilization seems to have rendered less common in spain than in the rest of europe. conviviality, candour, and great simplicity of manner, unite the different classes of society in the colonies, as well as in the mother-country. it may even be said, that the expression of vanity and self-love becomes less offensive, when it retains something of simplicity and frankness. i found in several families at caracas a love of information, an acquaintance with the masterpieces of french and italian literature, and a marked predilection for music, which is greatly cultivated, and which (as always results from a taste for the fine arts) brings the different classes of society nearer to each other. the mathematical sciences, drawing, and painting, cannot here boast of any of those establishments with which royal munificence and the patriotic zeal of the inhabitants have enriched mexico. in the midst of the marvels of nature, so rich in interesting productions, it is strange that we found no person on this coast devoted to the study of plants and minerals. in a franciscan convent i met, it is true, with an old monk who drew up the almanac for all the provinces of venezuela, and who possessed some accurate knowledge of astronomy. our instruments interested him deeply, and one day our house was filled with all the monks of san francisco, begging to see a dipping-needle. the curiosity excited by physical phenomena is naturally great in countries undermined by volcanic fires, and in a climate where nature is at once so majestic and so mysteriously convulsed. when we remember, that in the united states of north america, newspapers are published in small towns not containing more than three thousand inhabitants, it seems surprising that caracas, with a population of forty or fifty thousand souls, should have possessed no printing office before ; for we cannot give the name of a printing establishment to a few presses which served only from year to year to promulgate an almanac of a few pages, or the pastoral letter of a bishop. though the number of those who feel reading to be a necessity is not very considerable, even in the spanish colonies most advanced in civilization, yet it would be unjust to reproach the colonists for a state of intellectual lassitude which has been the result of a jealous policy. a frenchman, named delpeche, has the merit of having established the first printing office in caracas. it appears somewhat extraordinary that an establishment of this kind should have followed, and not preceded, a political revolution. in a country abounding in such magnificent scenery, and at a period when, notwithstanding some symptoms of popular commotion, most of the inhabitants seem only to direct attention to physical objects, such as the fertility of the year, the long drought, or the conflicting winds of petare and catia, i expected to find many individuals well acquainted with the lofty surrounding mountains. but i was disappointed; and we could not find in caracas a single person who had visited the summit of the silla. hunters do not ascend so high on the ridges of mountains; and in these countries journeys are not undertaken for such purposes as gathering alpine plants, carrying a barometer to an elevated point, or examining the nature of rocks. accustomed to a uniform and domestic life, the people dread fatigue and sudden changes of climate. they seem to live not to enjoy life, but only to prolong it. our walks led us often in the direction of two coffee plantations, the proprietors of which, don andres de ibarra and m. blandin, were men of agreeable manners. these plantations were situated opposite the silla de caracas. surveying, by a telescope, the steep declivity of the mountains, and the form of the two peaks by which it is terminated, we could form an idea of the difficulties we should have to encounter in reaching its summit. angles of elevation, taken with the sextant at our house, had led me to believe that the summit was not so high above sea-level as the great square of quito. this estimate was far from corresponding with the notions entertained by the inhabitants of the city. mountains which command great towns, have acquired, from that very circumstance, an extraordinary celebrity in both continents. long before they have been accurately measured, a conventional height is assigned to them; and to entertain the least doubt respecting that height is to wound a national prejudice. the captain-general, senor de guevara, directed the teniente of chacao to furnish us with guides to conduct us on our ascent of the silla. these guides were negroes, and they knew something of the path leading over the ridge of the mountain, near the western peak of the silla. this path is frequented by smugglers, but neither the guides, nor the most experienced of the militia, accustomed to pursue the smugglers in these wild spots, had been on the eastern peak, forming the most elevated summit of the silla. during the whole month of december, the mountain (of which the angles of elevation made me acquainted with the effects of the terrestrial refractions) had appeared only five times free of clouds. in this season two serene days seldom succeed each other, and we were therefore advised not to choose a clear day for our excursion, but rather a time when, the clouds not being elevated, we might hope, after having crossed the first layer of vapours uniformly spread, to enter into a dry and transparent air. we passed the night of the nd of january in the estancia de gallegos, a plantation of coffee-trees, near which the little river of chacaito, flowing in a luxuriantly shaded ravine, forms some fine cascades in descending the mountains. the night was pretty clear; and though on the day preceding a fatiguing journey it might have been well to have enjoyed some repose, m. bonpland and i passed the whole night in watching three occultations of the satellites of jupiter. i had previously determined the instant of the observation, but we missed them all, owing to some error of calculation in the connaissance des temps. the apparent time had been mistaken for mean time. i was much disappointed by this accident; and after having observed at the foot of the mountain the intensity of the magnetic forces, before sunrise, we set out at five in the morning, accompanied by slaves carrying our instruments. our party consisted of eighteen persons, and we all walked one behind another, in a narrow path, traced on a steep acclivity, covered with turf. we endeavoured first to reach a hill, which towards the south-east seems to form a promontory of the silla. it is connected with the body of the mountain by a narrow dyke, called by the shepherds the gate, or puerta de la silla. we reached this dyke about seven. the morning was fine and cool, and the sky till then seemed to favour our excursion. i saw that the thermometer kept a little below degrees ( . degrees reaum.). the barometer showed that we were already six hundred and eighty-five toises above the level of the sea, that is, nearly eighty toises higher than at the venta, where we enjoyed so magnificent a view of the coast. our guides thought that it would require six hours more to reach the summit of the silla. we crossed a narrow dyke of rocks covered with turf; which led us from the promontory of the puerta to the ridge of the great mountain. here the eye looks down on two valleys, or rather narrow defiles, filled with thick vegetation. on the right is perceived the ravine which descends between the two peaks to the farm of munoz; on the left we see the defile of chacaito, with its waters flowing out near the farm of gallegos. the roaring of the cascades is heard, while the water is unseen, being concealed by thick groves of erythrina, clusia, and the indian fig-tree.* (* ficus nymphaeifolia, erythrina mitis. two fine species of mimosa are found in the same valley; inga fastuosa, and i. cinerea.) nothing can be more picturesque, in a climate where so many plants have broad, large, shining, and coriaceous leaves, than the aspect of trees when the spectator looks down from a great height above them, and when they are illumined by the almost perpendicular rays of the sun. from the puerta de la silla the steepness of the ascent increases, and we were obliged to incline our bodies considerably forwards as we advanced. the slope is often from to degrees.* (* since my experiments on slopes, mentioned above in chapter . , i have discovered in the figure de la terre of bouguer, a passage, which shows that this astronomer, whose opinions are of such weight, considered also degrees as the inclination of a slope quite inaccessible, if the nature of the ground did not admit of forming steps with the foot.) we felt the want of cramp-irons, or sticks shod with iron. short grass covered the rocks of gneiss, and it was equally impossible to hold by the grass, or to form steps as we might have done in softer ground. this ascent, which was attended with more fatigue than danger, discouraged those who accompanied us from the town, and who were unaccustomed to climb mountains. we lost a great deal of time in waiting for them, and we did not resolve to proceed alone till we saw them descending the mountain instead of climbing up it. the weather was becoming cloudy; the mist already issued in the form of smoke, and in slender and perpendicular streaks, from a small humid wood which bordered the region of alpine savannahs above us. it seemed as if a fire had burst forth at once on several points of the forest. these streaks of vapour gradually accumulated together, and rising above the ground, were carried along by the morning breeze, and glided like a light cloud over the rounded summit of the mountain. m. bonpland and i foresaw from these infallible signs, that we should soon be covered by a thick fog; and lest our guides should take advantage of this circumstance and leave us, we obliged those who carried the most necessary instruments to precede us. we continued climbing the slopes which lead towards the ravine of chacaito. the familiar loquacity of the creole blacks formed a striking contrast with the taciturn gravity of the indians, who had constantly accompanied us in the missions of caripe. the negroes amused themselves by laughing at the persons who had been in such haste to abandon an expedition so long in preparation; above all, they did not spare a young capuchin monk, a professor of mathematics, who never ceased to boast of the superior physical strength and courage possessed by all classes of european spaniards over those born in spanish america. he had provided himself with long slips of white paper, which were to be cut, and flung on the savannah, to indicate to those who might stray behind, the direction they ought to follow. the professor had even promised the friars of his order to fire off some rockets, to announce to the whole town of caracas that we had succeeded in an enterprise which to him appeared of the utmost importance. he had forgotten that his long and heavy garments would embarrass him in the ascent. having lost courage long before the creoles, he passed the rest of the day in a neighbouring plantation, gazing at us through a glass directed to the silla, as we climbed the mountain. unfortunately for us, he had taken charge of the water and the provision so necessary in an excursion to the mountains. the slaves, who were to rejoin us, were so long detained by him, that they arrived very late, and we were ten hours without either bread or water. the eastern peak is the most elevated of the two which form the summit of the mountain, and to this we directed our course with our instruments. the hollow between these two peaks has suggested the spanish name of silla (saddle), which is given to the whole mountain. the narrow defile which we have already mentioned, descends from this hollow toward the valley of caracas, commencing near the western dome. the eastern summit is accessible only by going first to the west of the ravine over the promontory of the puerta, proceeding straight forward to the lower summit; and not turning to the east till the ridge, or the hollow of the silla between the two peaks, is nearly reached. the general aspect of the mountain points out this path; the rocks being so steep on the east of the ravine that it would be extremely difficult to reach the summit of the silla by ascending straight to the eastern dome, instead of going by the way of the puerta. from the foot of the cascade of chacaito to one thousand toises of elevation, we found only savannahs. two small liliaceous plants, with yellow flowers,* alone lift up their heads, among the grasses which cover the rocks. (* cypura martinicensis, and sisyrinchium iridifolium. this last is found also near the venta of la guayra, at toises of elevation.) a few brambles* (* rubus jamaicensis.) remind us of the form of our european vegetation. we in vain hoped to find on the mountains of caracas, and subsequently on the back of the andes, an eglantine near these brambles. we did not find one indigenous rose-tree in all south america, notwithstanding the analogy existing between the climates of the high mountains of the torrid zone and the climate of our temperate zone. it appears that this charming shrub is wanting in all the southern hemisphere, within and beyond the tropics. it was only on the mexican mountains that we were fortunate enough to discover, in the nineteenth degree of latitude, american eglantines.* (* m. redoute, in his superb work on rose-trees, has given our mexican eglantine, under the name of rosier de montezuma, montezuma rose.) we were sometimes so enveloped in mist, that we could not, without difficulty, find our way. at this height there is no path, and we were obliged to climb with our hands, when our feet failed us, on the steep and slippery acclivity. a vein filled with porcelain-clay attracted our attention.* (* the breadth of the vein is three feet. this porcelain-clay, when moistened, readily absorbs oxygen from the atmosphere. i found, at caracas, the residual nitrogen very slightly mingled with carbonic acid, though the experiment was made in phials with ground-glass stoppers, not filled with water.) it is of snowy whiteness, and is no doubt the remains of a decomposed feldspar. i forwarded a considerable portion of it to the intendant of the province. in a country where fuel is not scarce, a mixture of refractory earths may be useful, to improve the earthenware, and even the bricks. every time that the clouds surrounded us, the thermometer sunk as low as degrees (to . degrees r.); with a serene sky it rose to degrees. these observations were made in the shade. but it is difficult, on such rapid declivities, covered with a dry, shining, yellow turf, to avoid the effects of radiant heat. we were at nine hundred and forty toises of elevation; and yet at the same height, towards the east, we perceived in a ravine, not merely a few solitary palm-trees, but a whole grove. it was the palma real; probably a species of the genus oreodoxa. this group of palms, at so considerable an elevation, formed a striking contrast with the willows* scattered on the depth of the more temperate valley of caracas. (* salix humboldtiana of willdenouw. on the alpine palm-trees, see my prolegomena de dist. plant. page .) we here discovered plants of european forms, situated below those of the torrid zone. after proceeding for the space of four hours across the savannahs, we entered into a little wood composed of shrubs and small trees, called el pejual; doubtless from the great abundance here of the pejoa (gaultheria odorata), a plant with very odoriferous leaves.* (* it is a great advantage of the spanish language, and a peculiarity which it shares in common with the latin, that, from the name of a tree, may be derived a word designating an association or group of trees of the same species. thus are formed the words olivar, robledar, and pinal, from olivo, roble, and pino. the hispano-americans have added tunal, pejual, guayaval, etc., places where a great many cactuses, gualtheria odoratas, and psidiums, grow together.) the steepness of the mountain became less considerable, and we felt an indescribable pleasure in examining the plants of this region. nowhere, perhaps, can be found collected together, in so small a space, productions so beautiful, and so remarkable in regard to the geography of plants. at the height of a thousand toises, the lofty savannahs of the hills terminate in a zone of shrubs which, by their appearance, their tortuous branches, their stiff leaves, and the magnitude and beauty of their purple flowers, remind us of what is called, in the cordilleras of the andes, the vegetation of the paramos and the punas.* (* for the explanation of these words, see above chapter . .) we there find the family of the alpine rhododendrons, the thibaudias, the andromedas, the vacciniums, and those befarias with resinous leaves, which we have several times compared to the rhododendron of our european alps. even when nature does not produce the same species in analogous climates, either in the plains of isothermal parallels,* (we may compare together either latitudes which in the same hemisphere present the same mean temperature (as, for instance, pennsylvania and the central part of france, chile and the southern part of new holland); or we may consider the relations that may exist between the vegetation of the two hemispheres under isothermal parallels.) or on table-lands, the temperature of which resembles that of places nearer the poles,* we still remark a striking resemblance of appearance and physiognomy in the vegetation of the most distant countries. (* the geography of plants comprises not merely an examination of the analogies observed in the same hemisphere; as between the vegetation of the pyrenees and that of the scandinavian plains; or between that of the cordilleras of peru and of the coasts of chile. it also investigates the relations between the alpine plants of both hemispheres. it compares the vegetation of the alleghanies and the cordilleras of mexico, with that of the mountains of chile and brazil. bearing in mind that every isothermal line has an alpine branch (as, for instance, that which connects upsala with a point in the swiss alps), the great problem of the analogy of vegetable forms may be defined as follows: st, examining in each hemisphere, and at the level of the coasts, the vegetation on the same isothermal line, especially near convex or concave summits; nd, comparing, with respect to the form of plants, on the same isothermal line north and south of the equator, the alpine branch with that traced in the plains; rd, comparing the vegetation on homonymous isothermal lines in the two hemispheres, either in the low regions, or in the alpine regions.) this phenomenon is one of the most curious in the history of organic forms. i say the history; for in vain would reason forbid man to form hypotheses on the origin of things; he still goes on puzzling himself with insoluble problems relating to the distribution of beings. a gramen of switzerland grows on the granitic rocks of the straits of magellan.* (* phleum alpinum, examined by mr. brown. the investigations of this great botanist prove that a certain number of plants are at once common to both hemispheres. potentilla anserina, prunella vulgaris, scirpus mucronatus, and panicum crus-galli, grow in germany, in australia, and in pennsylvania.) new holland contains above forty european phanerogamous plants: and the greater number of those plants, which are found equally in the temperate zones of both hemispheres, are entirely wanting in the intermediary or equinoctial region, as well in the plains as on the mountains. a downy-leaved violet, which terminates in some sort the zone of the phanerogamous plants at teneriffe, and which was long thought peculiar to that island,* is seen three hundred leagues farther north, near the snowy summit of the pyrenees. (* the viola cheiranthifolia has been found by mm. kunth and von buch among the alpine plants which jussieu brought from the pyrenees.) gramina and cyperaceous plants of germany, arabia, and senegal, have been recognized among those that were gathered by m. bonpland and myself on the cold table-lands of mexico, along the burning shores of the orinoco, and in the southern hemisphere on the andes and quito.* (* cyperus mucronatus, poa eragrostis, festuca myurus, andropogos avenaceus, lapago racemosa. (see the nova genera et species plantarum volume page .)) how can we conceive the migration of plants through regions now covered by the ocean? how have the germs of organic life, which resemble each other in their appearance, and even in their internal structure, unfolded themselves at unequal distances from the poles and from the surface of the seas, wherever places so distant present any analogy of temperature? notwithstanding the influence exercised on the vital functions of plants by the pressure of the air, and the greater or less extinction of light, heat, unequally distributed in different seasons of the year, must doubtless be considered as the most powerful stimulus of vegetation. the number of identical species in the two continents and in the two hemispheres is far less than the statements of early travellers would lead us to believe. the lofty mountains of equinoctial america have certainly plantains, valerians, arenarias, ranunculuses, medlars, oaks, and pines, which from their physiognomy we might confound with those of europe; but they are all specifically different. when nature does not present the same species, she loves to repeat the same genera. neighbouring species are often placed at enormous distances from each other, in the low regions of the temperate zone, and on the alpine heights of the equator. at other times (and the silla of caracas affords a striking example of this phenomenon), they are not the european genera, which have sent species to people like colonists the mountains of the torrid zone, but genera of the same tribe, difficult to be distinguished by their appearance, which take the place of each other in different latitudes. the mountains of new grenada surrounding the table-lands of bogota are more than two hundred leagues distant from those of caracas, and yet the silla, the only elevated peak in the chain of low mountains, presents those singular groupings of befarias with purple flowers, of andromedas, of gualtherias, of myrtilli, of uvas camaronas,* (* the names vine-tree, and uvas camaronas, are given in the andes to plants of the genus thibaudia, on account of their large succulent fruits. thus the ancient botanists gave the name of bear's vine, uva ursi, and vine of mount ida (vitis idaea), to an arbutus and a myrtillus, which belong, like the thibaudia, to the family of the ericineae.) of nerteras, and of aralias with hoary leaves,* (* nertera depressa, aralia reticulata, hedyotis blaerioides.) which characterize the vegetation of the paramos on the high cordilleras of santa fe. we found the same thibaudia glandulosa at the entrance of the table-land of bogota, and in the pejual of the silla. the coast-chain of caracas is unquestionably connected (by the torito, the palomera, tocuyo, and the paramos of rosas, of bocono, and of niquitao) with the high cordilleras of merida, pamplona, and santa fe; but from the silla to tocuyo, along a distance of seventy leagues, the mountains of caracas are so low, that the shrubs of the family of the ericineous plants, just cited, do not find the cold climate which is necessary for their development. supposing, as is probable, that the thibaudias and the rhododendron of the andes, or befaria, exist in the paramo of niquitao and in the sierra de merida, covered with eternal snow, these plants would nevertheless want a ridge sufficiently lofty and long for their migration towards the silla of caracas. the more we study the distribution of organized beings on the globe, the more we are inclined, if not to abandon the ideas of migration, at least to consider them as hypotheses not entirely satisfactory. the chain of the andes divides the whole of south america into two unequal longitudinal parts. at the foot of this chain, on the east and west, we found a great number of plants specifically the same. the various passages of the cordilleras nowhere permit the vegetable productions of the warm regions to proceed from the coasts of the pacific to the banks of the amazon. when a peak attains a great elevation, either in the middle of very low mountains and plains, or in the centre of an archipelago heaved up by volcanic fires, its summit is covered with alpine plants, many of which are again found, at immense distances, on other mountains having an analogous climate. such are the general phenomena of the distribution of plants. it is now said that a mountain is high enough to enter into the limits of the rhododendrons and the befarias, as it has long been said that such a mountain reached the limit of perpetual snow. in using this expression, it is tacitly admitted, that under the influence of certain temperatures, certain vegetable forms must necessarily be developed. such a supposition, however, taken in all its generality, is not strictly accurate. the pines of mexico are wanting on the cordilleras of peru. the silla of caracas is not covered with the oaks which flourish in new grenada at the same height. identity of forms indicates an analogy of climate; but in similar climates the species may be singularly diversified. the charming rhododendron of the andes (the befaria) was first described by m. mutis, who observed it near pamplona and santa fe de bogota, in the fourth and seventh degree of north latitude. it was so little known before our expedition to the silla, that it was scarcely to be found in any herbal in europe. the learned editors of the flora of peru had even described it under another name, that of acunna. in the same manner as the rhododendrons of lapland, caucasus, and the alps* (* rhododendron lapponicum, r. caucasicum, r. ferrugineum, and r. hirsutum.) differ from each other, the two species of befaria we brought from the silla* (* befaria glauca, b. ledifolia.) are also specifically different from that of santa fe and bogota.* (* befaria aestuans, and b. resinosa.) near the equator the rhododendrons of the andes (particularly b. aestuans of mutis, and two new species of the southern hemisphere, which we have described under the name of b. coarctata, and b. grandiflora.) cover the mountains as far as the highest paramos, at sixteen and seventeen hundred toises of elevation. advancing northward, on the silla de caracas, we find them much lower, a little below one thousand toises. the befaria recently discovered in florida, in latitude degrees, grows even on hills of small elevation. thus in a space of six hundred leagues in latitude, these shrubs descend towards the plains in proportion as their distance from the equator augments. the rhododendron of lapland grows also at eight or nine hundred toises lower than the rhododendron of the alps and the pyrenees. we were surprised at not meeting with any species of befaria in the mountains of mexico, between the rhododendrons of santa fe and caracas, and those of florida. in the small grove which crowns the silla, the befaria ledifolia is only three or four feet high. the trunk is divided from its root into a great many slender and even verticillate branches. the leaves are oval, lanceolate, glaucous on their inferior part, and curled at the edges. the whole plant is covered with long and viscous hairs, and emits a very agreeable resinous smell. the bees visit its fine purple flowers, which are very abundant, as in all the alpine plants, and, when in full blossom, they are often nearly an inch wide. the rhododendron of switzerland, in those places where it grows, at the elevation of between eight hundred and a thousand toises, belongs to a climate, the mean temperature of which is + and- degrees, like that of the plains of lapland. in this zone the coldest months are- , and- degrees: the hottest, and degrees. thermometrical observations, made at the same heights and in the same latitudes, render it probable that, at the pejual of the silla, one thousand toises above the caribbean sea, the mean temperature of the air is still or degrees; and that the thermometer keeps, in the coolest season, between and degrees in the day, and in the night between and degrees. at the hospital of st. gothard, situated nearly on the highest limit of the rhododendron of the alps, the maximum of heat, in the month of august at noon, in the shade, is usually or degrees; in the night, at the same season, the air is cooled by the radiation of the soil down to + or- . degrees. under the same barometric pressure, consequently at the same height, but thirty degrees of latitude nearer the equator, the befaria of the silla is often, at noon, in the sun, exposed to a heat of or degrees. the greatest nocturnal refrigeration probably never exceeds degrees. we have carefully compared the climate, under the influence of which, at different latitudes, two groups of plants of the same family vegetate at equal heights above the level of the sea. the results would have been far different, had we compared zones equally distant, either from the perpetual snow, or from the isothermal line of degrees.* (* the stratum of air, the mean temperature of which is degrees, and which scarcely coincides with the superior limit of perpetual snow, is found in the parallel of the rhododendrons of switzerland at nine hundred toises; in the parallel of the befarias of caracas, at two thousand seven hundred toises of elevation.) in the little thicket of the pejual, near the purple-flowered befaria, grows a heath-leaved hedyotis, eight feet high; the caparosa,* which is a large arborescent hypericum (* vismia caparosa (a loranthus clings to this plant, and appropriates to itself the yellow juice of the vismia); davallia meifolia, heracium avilae, aralia arborea, jacq., and lepidium virginicum. two new species of lycopodium, the thyoides, and the aristatum, are seen lower down, near the puerto de la silla.); a lepidium, which appears identical with that of virginia; and lastly, lycopodiaceous plants and mosses, which cover the rocks and roots of the trees. that which gives most celebrity in the country to the little thicket, is a shrub ten or fifteen feet high, of the corymbiferous family. the creoles call it incense (incienso).* (* trixis nereifolia of m. bonpland.) its tough and crenate leaves, as well as the extremities of the branches, are covered with a white wool. it is a new species of trixis, extremely resinous, the flowers of which have the agreeable odour of storax. this smell is very different from that emitted by the leaves of the trixis terebinthinacea of the mountains of jamaica, opposite to those of caracas. the people sometimes mix the incienso of the silla with the flowers of the pevetera, another composite plant, the smell of which resembles that of the heliotropium of peru. the pevetera does not, however, grow on the mountains so high as the zone of the befarias; it vegetates in the valley of chacao, and the ladies of caracas prepare from it an extremely pleasant odoriferous water. we spent a long time in examining the fine resinous and fragrant plants of the pejual. the sky became more and more cloudy, and the thermometer sank below degrees, a temperature at which, in this zone, people begin to suffer from the cold. quitting the little thicket of alpine plants, we found ourselves again in a savannah. we climbed over a part of the western dome, in order to descend into the hollow of the silla, a valley which separates the two summits of the mountain. we there had great difficulties to overcome, occasioned by the force of the vegetation. a botanist would not readily guess that the thick wood covering this valley is formed by the assemblage of a plant of the musaceous family.* (*scitamineous plants, or family of the plantains.) it is probably a maranta, or a heliconia; its leaves are large and shining; it reaches the height of fourteen or fifteen feet, and its succulent stalks grow near one another like the stems of the reeds found in the humid regions of the south of europe.* (* arundo donax.) we were obliged to cut our way through this forest. the negroes walked before with their cutlasses or machetes. the people confound this alpine scitamineous plant with the arborescent gramina, under the name of carice. we saw neither its fruit nor flowers. we are surprised to meet with a monocotyledonous family, believed to be exclusively found in the hot and low regions of the tropics, at eleven hundred toises of elevation; much higher than the andromedas, the thibaudias, and the rhododendron of the cordilleras.* (* befaria.) in a chain of mountains no less elevated, and more northern (the blue mountains of jamaica), the heliconia of the parrots and the bihai, rather grow in the alpine shaded situations.* (* heliconia psittacorum, and h. bihai. these two heliconias are very common in the plains of terra firma.) wandering in this thick wood of musaceae or arborescent plants, we constantly directed our course towards the eastern peak, which we perceived from time to time through an opening. on a sudden we found ourselves enveloped in a thick mist; the compass alone could guide us; but in advancing northward we were in danger at every step of finding ourselves on the brink of that enormous wall of rocks, which descends almost perpendicularly to the depth of six thousand feet towards the sea. we were obliged to halt. surrounded by clouds sweeping the ground, we began to doubt whether we should reach the eastern peak before night. happily, the negroes who carried our water and provisions, rejoined us, and we resolved to take some refreshment. our repast did not last long. possibly the capuchin father had not thought of the great number of persons who accompanied us, or perhaps the slaves had made free with our provisions on the way; be that as it may, we found nothing but olives, and scarcely any bread. horace, in his retreat at tibur, never boasted of a repast more light and frugal; but olives, which might have afforded a satisfactory meal to a poet, devoted to study, and leading a sedentary life, appeared an aliment by no means sufficiently substantial for travellers climbing mountains. we had watched the greater part of the night, and we walked for nine hours without finding a single spring. our guides were discouraged; they wished to go back, and we had great difficulty in preventing them. in the midst of the mist i made trial of the electrometer of volta, armed with a smoking match. though very near a thick wood of heliconias, i obtained very sensible signs of atmospheric electricity. it often varied from positive to negative, its intensity changing every instant. these variations, and the conflict of several small currents of air, which divided the mist, and transformed it into clouds, the borders of which were visible, appeared to me infallible prognostics of a change in the weather. it was only two o'clock in the afternoon; we entertained some hope of reaching the eastern summit of the silla before sunset, and of re-descending into the valley separating the two peaks, intending there to pass the night, to light a great fire, and to make our negroes construct a hut with the leaves of the heliconia. we sent off half of our servants with orders to hasten the next morning to meet us, not with olives, but with a supply of salt beef. we had scarcely made these arrangements when the east wind began to blow violently from the sea. the thermometer rose to . degrees. it was no doubt an ascending wind, which, by heightening the temperature, dissolved the vapours. in less than two minutes the clouds dispersed, and the two domes of the silla appeared to us singularly near. we opened the barometer in the lowest part of the hollow that separates the two summits, near a little pool of very muddy water. here, as in the west india islands, marshy plains are found at great elevations; not because the woody mountains attract the clouds, but because they condense the vapours by the effect of nocturnal refrigeration, occasioned by the radiation of heat from the ground, and from the parenchyma of the leaves. the mercury was at inches . lines. we shaped our course direct to the eastern summit. the obstruction caused by the vegetation gradually diminished; it was, however, necessary to cut down some heliconias; but these arborescent plants were not now very thick or high. the peaks of the silla themselves, as we have several times mentioned, are covered only with gramina and small shrubs of befaria. their barrenness, however, is not owing to their height: the limit of trees in this region is four hundred toises higher; since, judging according to the analogy of other mountains, this limit would be found here only at a height of eighteen hundred toises. the absence of large trees on the two rocky summits of the silla may be attributed to the aridity of the soil, the violence of the winds blowing from the sea, and the conflagrations so frequent in all the mountains of the equinoctial region. to reach the eastern peak, which is the highest, it is necessary to approach as near as possible the great precipice which descends towards caravalleda and the coast. the gneiss as far as this spot preserves its lamellar texture and its primitive direction; but where we climbed the summit of the silla, we found it had passed into granite. its texture becomes granular; the mica, less frequent, is more unequally spread through the rock. instead of garnets we met with a few solitary crystals of hornblende. it is, however, not a syenite, but rather a granite of new formation. we were three quarters of an hour in reaching the summit of the pyramid. this part of the way is not dangerous, provided the traveller carefully examines the stability of each fragment of rock on which he places his foot. the granite superposed on the gneiss does not present a regular separation into beds: it is divided by clefts, which often cross one another at right angles. prismatic blocks, one foot wide and twelve long, stand out from the ground obliquely, and appear on the edges of the precipice like enormous beams suspended over the abyss. having arrived at the summit, we enjoyed, for a few minutes only, the serenity of the sky. the eye ranged over a vast extent of country: looking down to the north was the sea, and to the south, the fertile valley of caracas. the barometer was at inches . lines; the thermometer at . degrees. we were at thirteen hundred and fifty toises of elevation. we gazed on an extent of sea, the radius of which was thirty-six leagues. persons who are affected by looking downward from a considerable height should remain at the centre of the small flat which crowns the eastern summit of the silla. the mountain is not very remarkable for height: it is nearly eighty toises lower than the canigou; but it is distinguished among all the mountains i have visited by an enormous precipice on the side next the sea. the coast forms only a narrow border; and looking from the summit of the pyramid on the houses of caravalleda, this wall of rocks seems, by an optical illusion, to be nearly perpendicular. the real slope of the declivity appeared to me, according to an exact calculation, degrees minutes.* (* observations of the latitude give for the horizontal distance between the foot of the mountain near caravalleda, and the vertical line passing through its summit, scarcely toises.) the mean slope of the peak of teneriffe is scarcely degrees minutes. a precipice of six or seven thousand feet, like that of the silla of caracas, is a phenomenon far more rare than is generally believed by those who cross mountains without measuring their height, their bulk, and their slope. since the experiments on the fall of bodies, and on their deviation to the south-east, have been resumed in several parts of europe, a rock of two hundred and fifty toises of perpendicular elevation has been in vain sought for among all the alps of switzerland. the declivity of mont blanc towards the allee blanche does not even reach an angle of degrees; though in the greater number of geological works, mont blanc is described as perpendicular on the south side. at the silla of caracas, the enormous northern cliff is partly covered with vegetation, notwithstanding the extreme steepness of its slope. tufts of befaria and andromedas appear as if suspended from the rock. the little valley which separates the domes towards the south, stretches in the direction of the sea. alpine plants fill this hollow; and, not confined to the ridge of the mountain, they follow the sinuosities of the ravine. it would seem as if torrents were concealed under that fresh foliage; and the disposition of the plants, the grouping of so many inanimate objects, give the landscape all the charm of motion and of life. seven months had now elapsed since we had been on the summit of the peak of teneriffe, whence we surveyed a space of the globe equal to a fourth part of france. the apparent horizon of the sea is there six leagues farther distant than at the top of the silla, and yet we saw that horizon, at least for some time, very distinctly. it was strongly marked, and not confounded with the adjacent strata of air. at the silla, which is five hundred and fifty toises lower than the peak of teneriffe, the horizon, though nearer, continued invisible towards the north and north-north-east. following with the eye the surface of the sea, which was smooth as glass, we were struck with the progressive diminution of the reflected light. where the visual ray touched the last limit of that surface, the water was lost among the superposed strata of air. this appearance has something in it very extraordinary. we expect to see the horizon level with the eye; but, instead of distinguishing at this height a marked limit between the two elements, the more distant strata of water seem to be transformed into vapour, and mingled with the aerial ocean. i observed the same appearance, not in one spot of the horizon alone, but on an extent of more than a hundred and sixty degrees, along the pacific, when i found myself for the first time on the pointed rock that commands the crater of pichincha; a volcano, the elevation of which exceeds that of mont blanc.* (* see views of nature, bohn's edition, page .) the visibility of a very distant horizon depends, when there is no mirage, upon two distinct things: the quantity of light received on that part of the sea where the visual ray terminates; and the extinction of the reflected light during its passage through the intermediate strata of air. it may happen, notwithstanding the serenity of the sky and the transparency of the atmosphere, that the ocean is feebly illuminated at thirty or forty leagues' distance; or that the strata of air nearest the earth may extinguish a great deal of the light, by absorbing the rays that traverse them. the rounded peak, or western dome of the silla, concealed from us the view of the town of caracas; but we distinguished the nearest houses, the villages of chacao and petare, the coffee plantations, and the course of the rio guayra, a slender streak of water reflecting a silvery light. the narrow band of cultivated ground was pleasingly contrasted with the wild and gloomy aspect of the neighbouring mountains. whilst contemplating these grand scenes, we feel little regret that the solitudes of the new world are not embellished with the monuments of antiquity. but we could not long avail ourselves of the advantage arising from the position of the silla, in commanding all the neighbouring summits. while we were examining with our glasses that part of the sea, the horizon of which was clearly defined, and the chain of the mountains of ocumare, behind which begins the unknown world of the orinoco and the amazon, a thick fog from the plains rose to the elevated regions, first filling the bottom of the valley of caracas. the vapours, illumined from above, presented a uniform tint of a milky white. the valley seemed overspread with water, and looked like an arm of the sea, of which the adjacent mountains formed the steep shore. in vain we waited for the slave who carried ramsden's great sextant. eager to avail myself of the favourable state of the sky, i resolved to take a few solar altitudes with a sextant by troughton of two inches radius. the disk of the sun was half-concealed by the mist. the difference of longitude between the quarter of the trinidad and the eastern peak of the silla appears scarcely to exceed degrees minutes seconds.* (* the difference of longitude between the silla and la guayra, according to fidalgo, is degrees minutes seconds.) whilst, seated on the rock, i was determining the dip of the needle, i found my hands covered with a species of hairy bee, a little smaller than the honey-bee of the north of europe. these insects make their nests in the ground. they seldom fly; and, from the slowness of their movements, i should have supposed they were benumbed by the cold of the mountains. the people, in these regions, call them angelitos (little angels), because they very seldom sting. they are no doubt of the genus apis, of the division melipones. it has been erroneously affirmed that these bees, which are peculiar to the new world, are destitute of all offensive weapons. their sting is indeed comparatively feeble, and they use it seldom; but a person, not fully convinced of the harmlessness of these angelitos, can scarcely divest himself of a sensation of fear. i must confess, that, whilst engaged in my astronomical observations, i was often on the point of letting my instruments fall, when i felt my hands and face covered with these hairy bees. our guides assured us that they attempt to defend themselves only when irritated by being seized by their legs. i was not tempted to try the experiment on myself. the dip of the needle at the silla was one centesimal degree less than in the town of caracas. in collecting the observations which i made during calm weather and in very favourable circumstances, on the mountains as well as along the coast, it would at first seem, that we discover, in that part of the globe, a certain influence of the heights on the dip of the needle, and the intensity of the magnetical forces; but we must remark, that the dip at caracas is much greater than could be supposed, from the situation of the town, and that the magnetical phenomena are modified by the proximity of certain rocks, which constitute so many particular centres or little systems of attraction.* (* i have seen fragments of quartz traversed by parallel bands of magnetic iron, carried into the valley of caracas by the waters descending from the galipano and the cerro de avila. this banded magnetic iron-ore is found also in the sierra nevada of merida. between the two peaks of the silla, angular fragments of cellular quartz are found, covered with red oxide of iron. they do not act on the needle. this oxide is of a cinnabar-red colour.) the temperature of the atmosphere varied on the summit of the silla from eleven to fourteen degrees, according as the weather was calm or windy. every one knows how difficult it is to verify, on the summit of a mountain, the temperature, which is to serve for the barometric calculation. the wind was east, which would seem to prove that the trade-winds extend in this latitude much higher than fifteen hundred toises. von buch had observed that, at the peak of teneriffe, near the northern limit of the trade-winds, there exists generally at the elevation of one thousand nine hundred toises, a contrary current from the west. the academy of sciences recommended the men of science who accompanied the unfortunate la perouse, to employ small air-balloons for the purpose of ascertaining at sea the extent of the trade-winds within the tropics. such experiments are very difficult. small balloons do not in general reach the height of the silla; and the light clouds which are sometimes perceived at an elevation of three or four thousand toises, for instance, the fleecy clouds, called by the french moutons, remain almost fixed, or have such a slow motion, that it is impossible to judge of the direction of the wind. during the short space of time that the sky was serene at the zenith, i found the blue of the atmosphere sensibly deeper than on the coasts. it is probable that, in the months of july and august, the difference between the colour of the sky on the coasts and on the summit of the silla is still more considerable, but the meteorological phenomenon with which m. bonpland and myself were most struck during the hour we passed on the mountain, was the apparent dryness of the air, which seemed to increase as the fog augmented. this fog soon became so dense that it would have been imprudent to remain longer on the edge of a precipice of seven or eight thousand feet deep.* (* in the direction of north-west the slopes appear more accessible; and i have been told of a path frequented by smugglers, which leads to caravalleda, between the two peaks of the silla. from the eastern peak i took the bearings of the western peak, degrees minutes south-west; and of the houses, which i was told belonged to caravalleda, degrees minutes north-west. ) we descended the eastern dome of the silla, and gathered in our descent a gramen, which not only forms a new and very remarkable genus, but which, to our great astonishment, we found again some time after on the summit of the volcano of pichincha, at the distance of four hundred leagues from the silla, in the southern hemisphere.* (* aegopogon cenchroides.) the lichen floridus, so common in the north of europe, covered the branches of the befaria and the gualtheria odorata, descending even to the roots of these shrubs. examining the mosses which cover the rocks of gneiss in the valley between the two peaks, i was surprised at finding real pebbles,--rounded fragments of quartz.* (* fragments of brown copper-ore were found mixed with these pebbles, at an elevation of toises.) it may be conceived that the valley of caracas was once an inland lake, before the rio guayra found an issue to the east near caurimare, at the foot of the hill of auyamas, and before the ravine of tipe opened on the west, in the direction of gatia and cabo blanco. but how can we imagine that these waters could ascend as high as the silla, when the mountains opposite this peak, those of ocumare, were too low to prevent their overflow into the llanos? the pebbles could not have been brought by torrents from more elevated points, since there is no height that commands the silla. must we admit that they have been heaved up, like all the mountains which border the coast. it was half after four in the afternoon when we finished our observations. satisfied with the success of our journey, we forgot that there might be danger in descending in the dark, steep declivities covered by a smooth and slippery turf. the mist concealed the valley from us; but we distinguished the double hill of la puerta, which, like all objects lying almost perpendicularly beneath the eye, appeared extremely near. we relinquished our design of passing the night between the two summits of the silla, and having again found the path we had cut through the thick wood of heliconia, we soon arrived at the pejual, the region of odoriferous and resinous plants. the beauty of the befarias, and their branches covered with large purple flowers, again rivetted our attention. when, in these climates, a botanist gathers plants to form his herbal, he becomes difficult in his choice in proportion to the luxuriance of vegetation. he casts away those which have been first cut, because they appear less beautiful than those which were out of reach. though loaded with plants before quitting the pejual, we still regretted not having made a more ample harvest. we tarried so long in this spot, that night surprised us as we entered the savannah, at the elevation of upwards of nine hundred toises. as there is scarcely any twilight in the tropics, we pass suddenly from bright daylight to darkness. the moon was on the horizon; but her disk was veiled from time to time by thick clouds, drifted by a cold and rough wind. rapid slopes, covered with yellow and dry grass, now seen in shade, and now suddenly illumined, seemed like precipices, the depth of which the eye sought in vain to measure. we proceeded onwards, in single file, and endeavoured to support ourselves by our hands, lest we should roll down. the guides, who carried our instruments, abandoned us successively, to sleep on the mountain. among those who remained with us was a congo black, who evinced great address, bearing on his head a large dipping-needle: he held it constantly steady, notwithstanding the extreme declivity of the rocks. the fog had dispersed by degrees in the bottom of the valley; and the scattered lights we perceived below us caused a double illusion. the steeps appeared still more dangerous than they really were; and, during six hours of continual descent, we seemed to be always equally near the farms at the foot of the silla. we heard very distinctly the voices of men and the notes of guitars. sound is generally so well propagated upwards, that in a balloon at the elevation of three thousand toises, the barking of dogs is sometimes heard.* (* gay-lussac's account of his ascent on the th of september, .) we did not arrive till ten at night at the bottom of the valley. we were overcome with fatigue and thirst, having walked for fifteen hours, nearly without stopping. the soles of our feet were cut and torn by the asperities of a rocky soil and the hard and dry stalks of the gramina, for we had been obliged to pull off our boots, the soles having become too slippery. on declivities devoid of shrubs or ligneous herbs, which may be grasped by the hand, the danger of the descent is diminished by walking barefoot. in order to shorten the way, our guides conducted us from the puerta de la silla to the farm of gallegos by a path leading to a reservoir of water, called el tanque. they missed their way, however; and this last descent, the steepest of all, brought us near the ravine of chacaito. the noise of the cascades gave this nocturnal scene a grand and wild character. we passed the night at the foot of the silla. our friends at caracas had been able to distinguish us with glasses on the summit of the eastern peak. they felt interested in hearing the account of our expedition, but they were not satisfied with the result of our measurement, which did not assign to the silla even the elevation of the highest summit of the pyrenees.* (* it was formerly believed that the height of the silla of caracas scarcely differed from that of the peak of teneriffe.) one cannot blame the national feeling which suggests exaggerated ideas of the monuments of nature, in a country in which the monuments of art are nothing; nor can we wonder that the inhabitants of quito and riobamba, who have prided themselves for ages on the height of chimborazo, mistrust those measurements which elevate the mountains of himalaya above all the colossal cordilleras? during our journey to the silla, and in all our excursions in the valley of caracas, we were very attentive to the lodes and indications of ore which we found in the strata of gneiss. no regular diggings having been made, we could only examine the fissures, the ravines, and the land-slips occasioned by torrents in the rainy season. the rock of gneiss, passing sometimes into a granite of new formation, sometimes into mica-slate,* (* especially at great elevations.) belongs in germany to the most metalliferous rocks; but in the new continent, the gneiss has not hitherto been remarked as very rich in ores worth working. the most celebrated mines of mexico and peru are found in the primitive and transition schists, in the trap-porphyries, the grauwakke, and the alpine limestones. in several spots of the valley of caracas, the gneiss contains a small quantity of gold, disseminated in small veins of quartz, sulphuretted silver, azure copper-ore, and galena; but it is doubtful whether these different metalliferous substances are not too poor to encourage any attempt at working them. such attempts were, however, made at the conquest of the province, about the middle of the sixteenth century. from the promontory of paria to beyond cape vela, the early navigators had seen gold ornaments and gold dust, in the possession of the inhabitants of the coast. they penetrated into the interior of the country, to discover whence the precious metal came; and though the information obtained in the province of coro, and the markets of curiana and cauchieto,* (* the spaniards found, in , in the country of curiana (now coro), little birds, frogs, and other ornaments made of gold. those who had cast these figures lived at cauchieto, a place nearer the rio de la hacha. i have seen ornaments resembling those described by peter martyr of anghiera (which indicate tolerable skill in goldsmiths' work), among the remains of the ancient inhabitants of cundinamarca. the same art appears to have been practised in places along the coasts, and also farther to the south, among the mountains of new grenada.) clearly proved that real mineral wealth was to be found only to the west and south-west of coro (that is to say, in the mountains near those of new grenada), the whole province of caracas was nevertheless eagerly explored. a governor, newly arrived on that coast, could recommend himself to the spanish court only by boasting of the mines of his province; and in order to take from cupidity what was most ignoble and repulsive, the thirst of gold was justified by the purpose to which it was pretended the riches acquired by fraud and violence might be employed. "gold," says christopher columbus, in his last letter* (lettera rarissima data nelle indie nella isola di jamaica a julio dei .--"le oro e metallo sopra gli altri excellentissimo; e dell' oro si fanno li tesori e chi lo tiene fa e opera quanto vuole nel mondo[?], e finel[?]mente aggionge a mandare le anime al paradiso.") to king ferdinand, "gold is a thing so much the more necessary to your majesty, because, in order to fulfil the ancient prophecy, jerusalem is to be rebuilt by a prince of the spanish monarchy. gold is the most excellent of metals. what becomes of those precious stones, which are sought for at the extremities of the globe? they are sold, and are finally converted into gold. with gold we not only do whatever we please in this world, but we can even employ it to snatch souls from purgatory, and to people paradise." these words bear the stamp of the age in which columbus lived; but we are surprised to see this pompous eulogium of riches written by a man whose whole life was marked by the most noble disinterestedness. the conquest of the province of venezuela having been begun at its western extremity, the neighbouring mountains of coro, tocuyo, and barquisimeto, first attracted the attention of the conquistadores. these mountains join the cordilleras of new grenada (those of santa fe, pamplona, la grita, and merida) to the littoral chain of caracas. it is a land the more interesting in a geognostical point of view, as no map has yet made known the mountainous ramifications which the paramos of niquitao and las rosas send out towards the north-east. between tocuyo, araure, and barquisimeto, rises the group of the altar mountains, connected on the south-east with the paramo of las rosas. a branch of the altar stretches north-east by san felipe el fuerte, joining the granitic mountains of the coast near porto cabello. the other branch takes an eastward direction towards nirgua and tinaco, and joins the chain of the interior, that of yusma, villa de cura, and sabana de ocumare. the region we have been here describing separates the waters which flow to the orinoco from those which run into the immense lake of maracaybo and the caribbean sea. it includes climates which may be termed temperate rather than hot; and it is looked upon in the country, notwithstanding the distance of more than a hundred leagues, as a prolongation of the metalliferous soil of pamplona. it was in the group of the western mountains of venezuela, that the spaniards, in the year , worked the gold mine of buria,* (* real de minas de san felipe de buria.) which was the origin of the foundation of the town of barquisimeto.* (* nueva segovia.) but these works, like many other mines successively opened, were soon abandoned. here, as in all the mountains of venezuela, the produce of the ore has been found to be very variable. the lodes are very often divided, or they altogether cease; and the metals appear only in kidney-ores, and present the most delusive appearances. it is, however, only in this group of mountains of san felipe and barquisimeto, that the working of mines has been continued till the present time. those of aroa, near san felipe el fuerte, situated in the centre of a very insalubrious country, are the only mines which are wrought in the whole capitania-general of caracas. they yield a small quantity of copper. next to the works at buria, near barquisimeto, those of the valley of caracas, and of the mountains near the capital, are the most ancient. francisco faxardo and his wife isabella, of the nation of the guaiquerias,* often visited the table-land where the capital of venezuela is now situated. (* faxardo and his wife were the founders of the town of the collado, now called caravalleda.) they had given this table-land the name of valle de san francisco; and having seen some bits of gold in the hands of the natives, faxardo succeeded, in the year , in discovering the mines of los teques,* to the south-west of caracas, near the group of the mountains of cocuiza, which separate the valleys of caracas and aragua. (* thirteen years later, in , gabriel de avila, one of the alcaldes of the new town of caracas, renewed the working of these mines, which were from that time called the "real de minas de nuestra senora." probably this same avila, on account of a few farms which he possessed in the mountains adjacent to la guayra and caracas, has occasioned the cumbre to receive the name of montana de avila. this name has subsequently been applied erroneously to the silla, and to all the chain which extends towards cape codera.) it is thought that in the first of these valleys, near baruta, south of the village of valle, the natives had made some excavations in veins of auriferous quartz; and that, when the spaniards first settled there, and founded the town of caracas, they filled the shafts, which had been dry, with water. it is now impossible to ascertain this fact; but it is certain that, long before the conquest, grains of gold were a medium of exchange, i do not say generally, but among certain nations of the new continent. they gave gold for the purchase of pearls; and it does not appear extraordinary, that, after having for a long time picked up grains of gold in the rivulets, people who had fixed habitations, and were devoted to agriculture, should have tried to trace the auriferous veins in the superior surface of the soil. the mines of los teques could not be peaceably wrought, till the defeat of the cacique guaycaypuro, a celebrated chief of the teques, who long contested with the spaniards the possession of the province of venezuela. we have yet to mention a third point to which the attention of the conquistadores was called by indications of mines, so early as the end of the sixteenth century. in following the valley of caracas eastward beyond caurimare, on the road to caucagua, we reach a mountainous and woody country, where a great quantity of charcoal is now made, and which anciently bore the name of the province of los mariches. in these eastern mountains of venezuela, the gneiss passes into the state of talc. it contains, as at salzburg, lodes of auriferous quartz. the works anciently begun in those mines have often been abandoned and resumed. the mines of caracas were forgotten during more than a hundred years. but at a period comparatively recent, about the end of the last century, an intendant of venezuela, don jose avalo, again fell into the illusions which had flattered the cupidity of the conquistadores. he fancied that all the mountains near the capital contained great metallic riches. some mexican miners were engaged, and their operations were directed to the ravine of tipe, and the ancient mines of baruta to the south of caracas, where the indians gather even now some little gold-washings. but the zeal which had prompted the enterprise soon diminished, and after much useless expense, the working of the mines of caracas was totally abandoned. a small quantity of auriferous pyrites, sulphuretted silver, and a little native gold, were found; but these were only feeble indications; and in a country where labour is extremely dear, there was no inducement to pursue works so little productive. we visited the ravine of tipe, situated in that part of the valley which opens in the direction of cabo blanco. proceeding from caracas, we traverse, in the direction of the great barracks of san carlos, a barren and rocky soil. only a very few plants of argemone mexicana are to be found. the gneiss appears everywhere above ground. we might have fancied ourselves on the table-land of freiberg. we crossed first the little rivulet of agua salud, a limpid stream, which has no mineral taste, and then the rio garaguata. the road is commanded on the right by the cerro de avila and the cumbre; and on the left, by the mountains of aguas negras. this defile is very interesting in a geological point of view. at this spot the valley of caracas communicates, by the valleys of tacagua and of tipe, with the coast near catia. a ridge of rock, the summit of which is forty toises above the bottom of the valley of caracas, and more than three hundred toises above the valley of tacagua, divides the waters which flow into the rio guayra and towards cabo blanco. on this point of division, at the entrance of the branch, the view is highly pleasing. the climate changes as we descend westward. in the valley of tacagua we found some new habitations, and also conucos of maize and plantains. a very extensive plantation of tuna, or cactus, stamps this barren country with a peculiar character. the cactuses reach the height of fifteen feet, and grow in the form of candelabra, like the euphorbia of africa. they are cultivated for the purpose of selling their refreshing fruits in the market of caracas. the variety which has no thorns is called, strangely enough, in the colonies, tuna de espana (spanish cactus). we measured, at the same place, magueys or agaves, the long stems of which, laden with flowers, were forty-four feet high. however common this plant is become in the south of europe, the native of a northern climate is never weary of admiring the rapid development of a liliaceous plant, which contains at once a sweet juice and astringent and caustic liquids, employed to cauterize wounds. we found several veins of quartz in the valley of tipe visible above the soil. they contained pyrites, carbonated iron-ore, traces of sulphuretted silver (glasserz), and grey copper-ore (fahlerz). the works which had been undertaken, either for extracting the ore, or exploring the nature of its bed, appeared to be very superficial. the earth falling in had filled up those excavations, and we could not judge of the richness of the lode. notwithstanding the expense incurred under the intendancy of don jose avalo, the great question whether the province of venezuela contains mines rich enough to be worked, is yet problematical. though in countries where hands are wanting, the culture of the soil demands unquestionably the first care of the government, yet the example of new spain sufficiently proves that mining is not always unfavourable to the progress of agriculture. the best-cultivated mexican lands, those which remind the traveller of the most beautiful districts of france and the south of germany, extend from silao towards the villa of leon: they are in the neighbourhood of the mines of guanaxuato, which alone furnish a sixth part of all the silver of the new world. chapter . . earthquakes at caracas. connection of those phenomena with the volcanic eruptions of the west india islands. on the evening of the th of february we took our departure from caracas. since the period of our visit to that place, tremendous earthquakes have changed the surface of the soil. the city, which i have described, has disappeared; and on the same spot, on the ground fissured in various directions, another city is now slowly rising. the heaps of ruins, which were the grave of a numerous population, are becoming anew the habitation of men. in retracing changes of so general an interest, i shall be led to notice events which took place long after my return to europe. i shall pass over in silence the popular commotions which have taken place, and the modifications which society has undergone. modern nations, careful of their own remembrances, snatch from oblivion the history of human revolutions, which is, in fact, the history of ardent passions and inveterate hatred. it is not the same with respect to the revolutions of the physical world. these are described with least accuracy when they happen to be contemporary with civil dissensions. earthquakes and eruptions of volcanoes strike the imagination by the evils which are their necessary consequence. tradition seizes on whatever is vague and marvellous; and amid great public calamities, as in private misfortunes, man seems to shun that light which leads us to discover the real causes of events, and to understand the circumstances by which they are attended. i have recorded in this work all i have been able to collect, and on the accuracy of which i can rely, respecting the earthquake of the th of march, . by that catastrophe the town of caracas was destroyed, and more than twenty thousand persons perished throughout the extent of the province of venezuela. the intercourse which i have kept up with persons of all classes has enabled me to compare the description given by many eye-witnesses, and to interrogate them on objects that may throw light on physical science in general. the traveller, as the historian of nature, should verify the dates of great catastrophes, examine their connection and their mutual relations, and should mark in the rapid course of ages, in the continual progress of successive changes, those fixed points with which other catastrophes may one day be compared. all epochs are proximate to each other in the immensity of time comprehended in the history of nature. years which have passed away seem but a few instants; and the physical descriptions of a country, even when they offer subjects of no very powerful and general interest, have at least the advantage of never becoming old. similar considerations, no doubt, led m. de la condamine to describe in his voyage a l'equateur, the memorable eruptions of the volcano of cotopaxi,* which took place long after his departure from quito. (* those of the th of november, , and of the rd of september, .) i feel the less hesitation in following the example of that celebrated traveller, as the events i am about to relate will help to elucidate the theory of volcanic reaction, or the influence of a system of volcanoes on a vast space of circumjacent territory. at the time when m. bonpland and myself visited the provinces of new andalusia, new barcelona, and caracas, it was generally believed that the most eastern parts of those coasts were especially exposed to the destructive effects of earthquakes. the inhabitants of cumana dreaded the valley of caracas, on account of its damp and variable climate, and its gloomy and misty sky; whilst the inhabitants of the temperate valley regarded cumana as a town whose inhabitants incessantly inhaled a burning atmosphere, and whose soil was periodically agitated by violent commotions. unmindful of the overthrow of riobamba and other very elevated towns, and not aware that the peninsula of araya, composed of mica-slate, shares the commotions of the calcareous coast of cumana, well-informed persons imagined they discerned security in the structure of the primitive rocks of caracas, as well as in the elevated situation of this valley. religious ceremonies celebrated at la guayra, and even in the capital, in the middle of the night,* doubtless called to mind the fact that the province of venezuela had been subject at intervals to earthquakes; but dangers of rare occurrence are slightly feared. (* for instance, the nocturnal procession of the st of october, instituted in commemoration of the great earthquake which took place on that day of the month, at one o'clock in the morning, in . other very violent shocks were those of , , and .) however, in the year , fatal experience destroyed the illusion of theory and of popular opinion. caracas, situated in the mountains, three degrees west of cumana, and five degrees west of the volcanoes of the caribbee islands, has suffered greater shocks than were ever experienced on the coast of paria or new andalusia. at my arrival in terra firma, i was struck with the connection between the destruction of cumana on the th of december, , and the eruption of the volcanoes in the smaller west india islands. this connection was again manifest in the destruction of caracas on the th of march, . the volcano of guadaloupe seemed in to have exercised a reaction on the coasts of cumana. fifteen years later, it was a volcano situated nearer the continent (that of st. vincent), which appeared to have extended its influence as far as caracas and the banks of apure. possibly, at both those periods, the centre of the explosion was, at an immense depth, equally distant from the regions towards which the motion was propagated at the surface of the globe. from the beginning of to , a vast superficies of the earth,* (* between latitudes and degrees north, and and degrees west longitude from paris.) bound by the meridian of the azores, the valley of the ohio, the cordilleras of new grenada, the coasts of venezuela, and the volcanoes of the smaller west india islands, was shaken throughout its whole extent, by commotions which may be attributed to subterranean fires. the following series of phenomena seems to indicate communications at enormous distances. on the th of january, , a submarine volcano broke out near the island of st. michael, one of the azores. at a place where the sea was sixty fathoms deep, a rock made its appearance above the surface of the waters. the heaving-up of the softened crust of the globe appears to have preceded the eruption of flame at the crater, as had already been observed at the volcanoes of jorullo in mexico, and on the appearance of the little island of kameni, near santorino. the new islet of the azores was at first a mere shoal; but on the th of june, an eruption, which lasted six days, enlarged its extent, and carried it progressively to the height of fifty toises above the surface of the sea. this new land, of which captain tillard took possession in the name of the british government, giving it the name of sabrina island, was nine hundred toises in diameter. it has again, it seems, been swallowed up by the ocean. this is the third time that submarine volcanoes have presented this extraordinary spectacle near the island of st. michael; and, as if the eruptions of these volcanoes were subject to periodical recurrence, owing to a certain accumulation of elastic fluids, the island raised up has appeared at intervals of ninety-one or ninety-two years.* (* malte-brun, geographie universelle. there is, however, some doubt respecting the eruption of , to which some accounts assign the date of . the rising always happened near the island of st. michael, though not identically on the same spot. it is remarkable that the small island of reached the same elevation as the island of sabrina in .) at the time of the appearance of the new island of sabrina, the smaller west india islands, situated eight hundred leagues south-west of the azores, experienced frequent earthquakes. more than two hundred shocks were felt from the month of may , to april , at st. vincent; one of the three islands in which there are still active volcanoes. the commotion was not circumscribed to the insular portion of eastern america; and from the th of december, , till the year , the earth was almost incessantly agitated in the valleys of the mississippi, the arkansas river, and the ohio. the oscillations were more feeble on the east of the alleghanies, than to the west of these mountains, in tennessee and kentucky. they were accompanied by a great subterranean noise, proceeding from the south-west. in some places between new madrid and little prairie, as at the saline, north of cincinnati, in latitude degrees minutes, shocks were felt every day, nay almost every hour, during several months. the whole of these phenomena continued from the th of december , till the year . the commotion, confined at first to the south, in the valley of the lower mississippi, appeared to advance slowly northward. precisely at the period when this long series of earthquakes commenced in the transalleghanian states (in the month of december ), the town of caracas felt the first shock in calm and serene weather. this coincidence of phenomena was probably not accidental; for it must be borne in mind that, notwithstanding the distance which separates these countries, the low grounds of louisiana and the coasts of venezuela and cumana belong to the same basin, that of the gulf of mexico. when we consider geologically the basin of the caribbean sea, and of the gulf of mexico, we find it bounded on the south by the coast-chain of venezuela and the cordilleras of merida and pamplona; on the east by the mountains of the west india islands, and the alleghanies; on the west by the andes of mexico, and the rocky mountains; and on the north by the very inconsiderable elevations which separate the canadian lakes from the rivers which flow into the mississippi. more than two-thirds of this basin are covered with water. it is bordered by two ranges of active volcanoes; on the east, in the carribee islands, between latitudes and degrees; and on the west in the cordilleras of nicaragua, guatimala, and mexico, between latitudes and degrees. when we reflect that the great earthquake at lisbon, of the st of november, , was felt almost simultaneously on the coasts of sweden, at lake ontario, and at the island of martinique, it may not seem unreasonable to suppose, that all this basin of the west indies, from cumana and caracas as far as the plains of louisiana, should be simultaneously agitated by commotions proceeding from the same centre of action. it is an opinion very generally prevalent on the coasts of terra firma, that earthquakes become more frequent when electric explosions have been during some years rare. it is supposed to have been observed, at cumana and at caracas, that the rains were less frequently attended with thunder from the year ; and the total destruction of cumana in , as well as the commotions felt in , , and , at maracaibo, porto cabello, and caracas, have not failed to be attributed to an accumulation of electricity in the interior of the earth. persons who have lived long in new andalusia, or in the low regions of peru, will admit that the period most to be dreaded for the frequency of earthquakes is the beginning of the rainy season, which, however, is also the season of thunder-storms. the atmosphere and the state of the surface of the globe seem to exercise an influence unknown to us on the changes which take place at great depths; and i am inclined to think that the connection which it is supposed has been traced between the absence of thunder-storms and the frequency of earthquakes, is rather a physical hypothesis framed by the half-learned of the country than the result of long experience. the coincidence of certain phenomena may be favoured by chance. the extraordinary commotions felt almost continually during the space of two years on the banks of the mississippi and the ohio, and which corresponded in with those of the valley of caracas, were preceded at louisiana by a year almost exempt from thunder-storms. the public mind was again struck with this phenomenon. we cannot be surprised that there should be in the native land of franklin a great readiness to receive explanations founded on the theory of electricity. the shock felt at caracas in the month of december , was the only one which preceded the terrible catastrophe of the th of march, . the inhabitants of terra firma were alike ignorant of the agitations of the volcano in the island of st. vincent, and of those felt in the basin of the mississippi, where, on the th and th of february, , the earth was day and night in perpetual oscillation. a great drought prevailed at this period in the province of venezuela. not a single drop of rain had fallen at caracas or in the country to the distance of ninety leagues round, during five months preceding the destruction of the capital. the th of march was a remarkably hot day. the air was calm, and the sky unclouded. it was ascension-day, and a great portion of the population was assembled in the churches. nothing seemed to presage the calamities of the day. at seven minutes after four in the afternoon the first shock was felt. it was sufficiently forcible to make the bells of the churches toll; and it lasted five or six seconds. during that interval the ground was in a continual undulating movement, and seemed to heave up like a boiling liquid. the danger was thought to be past, when a tremendous subterranean noise was heard, resembling the rolling of thunder, but louder and of longer continuance than that heard within the tropics in the time of storms. this noise preceded a perpendicular motion of three or four seconds, followed by an undulatory movement somewhat longer. the shocks were in opposite directions, proceeding from north to south, and from east to west. nothing could resist the perpendicular movement and the transverse undulations. the town of caracas was entirely overthrown, and between nine and ten thousand of the inhabitants were buried under the ruins of the houses and churches. the procession of ascension-day had not yet begun to pass through the streets, but the crowd was so great within the churches that nearly three or four thousand persons were crushed by the fall of the roofs. the explosion was most violent towards the north, in that part of the town situated nearest the mountain of avila and the silla. the churches of la trinidad and alta gracia, which were more than one hundred and fifty feet high, and the naves of which were supported by pillars of twelve or fifteen feet diameter, were reduced to a mass of ruins scarcely exceeding five or six feet in elevation. the sinking of the ruins has been so considerable that there now scarcely remain any vestiges of pillars or columns. the barracks, called el quartel de san carlos, situated north of the church of la trinidad, on the road from the custom-house of la pastora, almost entirely disappeared. a regiment of troops of the line, under arms, and in readiness to join the procession, was, with the exception of a few men, buried beneath the ruins of the barracks. nine-tenths of the fine city of caracas were entirely destroyed. the walls of some houses not thrown down, as those in the street san juan, near the capuchin hospital, were cracked in such a manner as to render them uninhabitable. the effects of the earthquake were somewhat less violent in the western and southern parts of the city, between the principal square and the ravine of caraguata. there, the cathedral, supported by enormous buttresses, remains standing. it is computed that nine or ten thousand persons were killed in the city of caracas, exclusive of those who, being dangerously wounded, perished several months after, for want of food and proper care. the night of the festival of the ascension witnessed an awful scene of desolation and distress. the thick cloud of dust which, rising above the ruins, darkened the sky like a fog, had settled on the ground. no commotion was felt, and never was a night more calm or more serene. the moon, then nearly at the full, illumined the rounded domes of the silla, and the aspect of the sky formed a perfect contrast to that of the earth, which was covered with the bodies of the dead, and heaped with ruins. mothers were seen bearing in their arms their children, whom they hoped to recall to life. desolate families were wandering through the city, seeking a brother, a husband, or a friend, of whose fate they were ignorant, and whom they believed to be lost in the crowd. the people pressed along the streets, which could be traced only by long lines of ruins. all the calamities experienced in the great catastrophes of lisbon, messina, lima, and riobamba were renewed at caracas on the fatal th of march, . wounded persons, buried beneath the ruins, were heard imploring by their cries the help of the passers-by, and nearly two thousand were dug out. never was pity more tenderly evinced; never was it more ingeniously active than in the efforts employed to save the miserable victims whose groans reached the ear. implements for digging and clearing away the ruins were entirely wanting; and the people were obliged to use their bare hands, to disinter the living. the wounded, as well as the invalids who had escaped from the hospitals, were laid on the banks of the small river guayra, where there was no shelter but the foliage of trees. beds, linen to dress the wounds, instruments of surgery, medicines, every object of the most urgent necessity, was buried in the ruins. everything, even food, was wanting; and for the space of several days water became scarce in the interior of the city. the commotion had rent the pipes of the fountains; and the falling in of the earth had choked up the springs that supplied them. to procure water it was necessary to go down to the river guayra, which was considerably swelled; and even when the water was obtained vessels for conveying it were wanting. there was a duty to be fulfilled to the dead, enjoined at once by piety and the dread of infection. it being impossible to inter so many thousand bodies, half-buried under the ruins, commissioners were appointed to burn them: and for this purpose funeral piles were erected between the heaps of ruins. this ceremony lasted several days. amidst so many public calamities, the people devoted themselves to those religious duties which they thought best fitted to appease the wrath of heaven. some, assembling in processions, sang funeral hymns; others, in a state of distraction, made their confessions aloud in the streets. in caracas was then repeated what had been remarked in the province of quito, after the tremendous earthquake of ; a number of marriages were contracted between persons who had neglected for many years to sanction their union by the sacerdotal benediction. children found parents, by whom they had never till then been acknowledged; restitutions were promised by persons who had never been accused of fraud; and families who had long been at enmity were drawn together by the tie of common calamity. but if this feeling seemed to calm the passions of some, and open the heart to pity, it had a contrary effect on others, rendering them more rigorous and inhuman. in great calamities vulgar minds evince less of goodness than of energy. misfortune acts in the same manner as the pursuits of literature and the study of nature; the happy influence of which is felt only by a few, giving more ardour to sentiment, more elevation to the thoughts, and increased benevolence to the disposition. shocks as violent as those which in about the space of a minute* overthrew the city of caracas, could not be confined to a small portion of the continent. (* the duration of the earthquake, that is to say the whole of the movements of undulation and rising (undulacion y trepidacion), which occasioned the horrible catastrophe of the th of march, , was estimated by some at seconds, by others at minute seconds.) their fatal effects extended as far as the provinces of venezuela, varinas, and maracaibo, along the coast; and especially to the inland mountains. la guayra, mayquetia, antimano, baruta, la vega, san felipe, and merida, were almost entirely destroyed. the number of the dead exceeded four or five thousand at la guayra, and at the town of san felipe, near the copper-mines of aroa. it would appear that on a line running east-north-east and west-south-west from la guayra and caracas to the lofty mountains of niquitao and merida, the violence of the earthquake was principally directed. it was felt in the kingdom of new grenada from the branches of the high sierra de santa martha* (* as far as villa de los remedios, and even to carthagena.) as far as santa fe de bogota and honda, on the banks of the magdalena, one hundred and eighty leagues from caracas. it was everywhere more violent in the cordilleras of gneiss and mica-slate, or immediately at their base, than in the plains; and this difference was particularly striking in the savannahs of varinas and casanara.* (* this is easily explained according to the system of those geologists who are of opinion that all chains of mountains, volcanic and not volcanic, have been formed by being raised up, as if through crevices.) in the valleys of aragua, between caracas and the town of san felipe, the commotions were very slight; and la victoria, maracay, and valencia, scarcely suffered at all, notwithstanding their proximity to the capital. at valecillo, a few leagues from valencia, the yawning earth threw out such an immense quantity of water, that it formed a new torrent. the same phenomenon took place near porto-cabello.* (* it is asserted that, in the mountains of aroa, the ground, immediately after the great shocks, was found covered with a very fine and white earth, which appeared to have been projected through crevices.) on the other hand, the lake of maracaybo diminished sensibly. at coro no commotion was felt, though the town is situated on the coast, between other towns which suffered from the earthquake. fishermen, who had passed the day of the th of march in the island of orchila, thirty leagues north-east of la guayra, felt no shock. these differences in the direction and propagation of the shock, are probably owing to the peculiar position of the stony strata. having thus traced the effects of the earthquake to the west of caracas, as far as the snowy mountains of santa martha, and the table-land of santa fe de bogota, we will proceed to consider their action on the country eastward of the capital. the commotions were very violent beyond caurimare, in the valley of capaya, where they extended as far as the meridian of cape codera: but it is extremely remarkable that they were very feeble on the coasts of nueva barcelona, cumana, and paria; though these coasts are the continuation of the shore of la guayra, and were formerly known to have been often agitated by subterranean commotions. admitting that the destruction of the four towns of caracas, la guayra, san felipe, and merida, may be attributed to a volcanic focus situated under or near the island of st. vincent, we may conceive that the motion might have been propagated from north-east to south-west in a line passing through the islands of los hermanos, near blanquilla, without touching the coasts of araya, cumana, and nueva barcelona. this propagation of the shock might even have taken place without any commotion having been felt at the intermediate points on the surface of the globe (the hermanos islands for instance). this phenomenon is frequently remarked at peru and mexico, in earthquakes which have followed during ages a fixed direction. the inhabitants of the andes say, speaking of an intermediary tract of ground, not affected by the general commotion, "that it forms a bridge" (que hace puente): as if they mean to indicate by this expression that the undulations are propagated at an immense depth under an inert rock. at caracas, fifteen or eighteen hours after the great catastrophe, the earth was tranquil. the night, as has already been observed, was fine and calm; and the commotions did not recommence till after the th. they were then attended by a very loud and long continued subterranean noise (bramido). the inhabitants of the destroyed city wandered into the country; but the villages and farms having suffered as much as the town, they could find no shelter till they were beyond the mountains of los teques, in the valleys of aragua, and in the llanos or savannahs. no less than fifteen oscillations were felt in one day. on the th of april there was almost as violent an earthquake as that which overthrew the capital. during several hours the ground was in a state of perpetual undulation. large heaps of earth fell in the mountains; and enormous masses of rock were detached from the silla of caracas. it was even asserted, and this opinion prevails still in the country, that the two domes of the silla sunk fifty or sixty toises; but this statement is not founded on any measurement. i am informed that, in like manner, in the province of quito, the people, at every period of great commotions, imagine that the volcano of tunguragua diminishes in height. it has been affirmed, in many published accounts of the destruction of caracas, that the mountain of the silla is an extinguished volcano; that a great quantity of volcanic substances are found on the road from la guayra to caracas; that the rocks do not present any regular stratification; and that everything bears the stamp of the action of fire. it has even been stated that twelve years prior to the great catastrophe, m. bonpland and myself had, from our own observations, considered the silla as a very dangerous neighbour to the city of caracas, because the mountain contained a great quantity of sulphur, and the commotions must come from the north-east. it is seldom that observers of nature have to justify themselves for an accomplished prediction; but i think it my duty to oppose ideas which are too easily adopted on the local causes of earthquakes. in all places where the soil has been incessantly agitated for whole months, as at jamaica in , lisbon in , cumana in , and piedmont in , a volcano is expected to open. people forget that we must seek the focus or centre of action, far from the surface of the earth; that, according to undeniable evidence, the undulations are propagated almost at the same instant across seas of immense depth, at the distance of a thousand leagues; and that the greatest commotions take place not at the foot of active volcanoes, but in chains of mountains composed of the most heterogeneous rocks. in our geognostical observation of the country round caracas we found gneiss, and mica-slate containing beds of primitive limestone. the strata are scarcely more fractured or irregularly inclined than near freyburg in saxony, or wherever mountains of primitive formation rise abruptly to great heights. i found at caracas neither basalt nor dorolite, nor even trachytes or trap-porphyries; nor in general any trace of an extinguished volcano, unless we choose to regard the diabases of primitive grunstein, contained in gneiss, as masses of lava, which have filled up fissures. these diabases are the same as those of bohemia, saxony, and franconia;* (* these grunsteins are found in bohemia, near pilsen, in granite; in saxony, in the mica-slates of scheenberg; in franconia, between steeben and lauenstein, in transition-slates.) and whatever opinion may be entertained respecting the ancient causes of the oxidation of the globe at its surface, all those primitive mountains, which contain a mixture of hornblende and feldspar, either in veins or in balls with concentric layers, will not, i presume, be called volcanic formations. mont blanc and mont d'or will not be ranged in one and the same class. even the partisans of the huttonian or volcanic theory make a distinction between the lavas melted under the mere pressure of the atmosphere at the surface of the globe, and those layers formed by fire beneath the immense weight of the ocean and superincumbent rocks. they would not confound auvergne and the granitic valley of caracas in the same denomination; that of a country of extinct volcanoes. i never could have pronounced the opinion, that the silla and the cerro de avila, mountains of gneiss and mica-slate, were in dangerous proximity to the city of caracas because they contained a great quantity of pyrites in subordinate beds of primitive limestone. but i remember having said, during my stay at caracas, that the eastern extremity of terra firma appeared, since the great earthquake of quito, in a state of agitation, which warranted apprehension that the province of venezuela would gradually be exposed to violent commotions. i added, that when a country had been long subject to frequent shocks, new subterranean communications seemed to open with neighbouring countries; and that the volcanoes of the west india islands, lying in the direction of the silla, north-east of the city, were perhaps the vents, at the time of an eruption, for those elastic fluids which cause earthquakes on the coasts of the continent. these considerations, founded on local knowledge of the place, and on simple analogies, are very far from a prediction justified by the course of physical events. on the th of april, , whilst violent commotions were felt simultaneously in the valley of the mississippi, in the island of st. vincent, and in the province of venezuela, a subterranean noise resembling frequent discharges of large cannon was heard at caracas, at calabozo (situated in the midst of the steppes), and on the borders of the rio apure, over a superficies of four thousand square leagues. this noise began at two in the morning. it was accompanied by no shock; and it is very remarkable, that it was as loud on the coast as at the distance of eighty leagues inland. it was everywhere believed to be transmitted through the air; and was so far from being thought a subterranean noise, that in several places, preparations were made for defence against an enemy, who seemed to be advancing with heavy artillery. senor palacio, crossing the rio apure below the orivante, near the junction of the rio nula, was told by the inhabitants, that the firing of cannon had been heard distinctly at the western extremity of the province of varinas, as well as at the port of la guayra to the north of the chain of the coast. the day on which the inhabitants of terra firma were alarmed by a subterranean noise was that of the great eruption of the volcano in the island of st. vincent. that mountain, near five hundred toises high, had not thrown out lava since the year . scarcely was any smoke perceived to issue from it, when, in the month of may , frequent shocks announced that the volcanic fire was either rekindled, or directed anew to that part of the west indies. the first eruption did not take place till the th of april, , at noon. it was merely an ejection of ashes, but attended with a tremendous noise. on the th, the lava overflowed the brink of the crater, and, after a course of four hours, reached the sea. the sound of the explosion is described as resembling that of alternate discharges of very large cannon and musketry; and it is worthy of remark, that it seemed much louder to persons out at sea, and at a great distance from land, than to those within sight of land, and near the burning volcano. the distance in a straight line from the volcano of st. vincent to the rio apure, near the mouth of the nula, is two hundred and ten leagues.* (* where the contrary is not expressly stated, nautical leagues of twenty to a degree, or two thousand eight hundred and fifty-five toises, are always to be understood.) the explosions were consequently heard at a distance equal to that between vesuvius and paris. this phenomenon, in conjunction with a great number of facts observed in the cordilleras of the andes, shows that the sphere of the subterranean activity of a volcano is much more extensive than we should be disposed to admit, if we judged merely from the small changes effected at the surface of the globe. the detonations heard during whole days together in the new world, eighty, one hundred, or even two hundred leagues distant from a crater, do not reach us by the propagation of the sound through the air; they are transmitted by the earth, perhaps in the very place where we happen to be. if the eruptions of the volcano of st. vincent, cotopaxi, or tunguragua, resounded from afar, like a cannon of immense magnitude, the noise ought to increase in the inverse ratio of the distance: but observations prove, that this augmentation does not take place. i must further observe, that m. bonpland and i, going from guayaquil to the coast of mexico, crossed latitudes in the pacific, where the crew of our ship were dismayed by a hollow sound coming from the depth of the ocean, and transmitted by the waters. at that time a new eruption of cotopaxi took place, but we were as far distant from the volcano, as etna from the city of naples. the little town of honda, on the banks of the magdalena, is not less than one hundred and forty-five leagues* (* this is the distance from vesuvius to mont blanc.) from cotopaxi; and yet, in the great explosions of this volcano, in , a subterranean noise was heard at honda, and supposed to be discharges of heavy artillery. the monks of san francisco spread a report that the town of carthagena was besieged and bombarded by the english; and the intelligence was believed throughout the country. now the volcano of cotopaxi is a cone, more than one thousand eight hundred toises above the basin of honda, and it rises from a table-land, the elevation of which is more than one thousand five hundred toises above the valley of the magdalena. in all the colossal mountains of quito, of the province of los pastos, and of popayan, crevices and valleys without number intervene. it cannot be admitted, under these circumstances, that the noise was transmitted through the air, or over the surface of the globe, and that it came from the point at which the cone and crater of cotapaxi are situated. it appears probable, that the more elevated part of the kingdom of quito and the neighbouring cordilleras, far from being a group of distinct volcanoes, constitute a single swollen mass, an enormous volcanic wall, stretching from south to north, and the crest of which presents a superficies of more than six hundred square leagues. cotopaxi, tunguragua, antisana, and pichincha, are on this same raised ground. they have different names, but they are merely separate summits of the same volcanic mass. the fire issues sometimes from one, sometimes from another of these summits. the obstructed craters appear to be extinguished volcanoes; but we may presume, that, while cotopaxi or tunguragua have only one or two eruptions in the course of a century, the fire is not less continually active under the town of quito, under pichincha and imbabura. advancing northward we find, between the volcano of cotopaxi and the town of honda, two other systems of volcanic mountains, those of los pastos and of popayan. the connection between these systems was manifested in the andes by a phenomenon which i have already had occasion to notice, in speaking of the last destruction of cumana. in the month of november a thick column of smoke began to issue from the volcano of pasto, west of the town of that name, and near the valley of rio guaytara. the mouths of the volcano are lateral, and situated on its western declivity, yet during three successive months the column of smoke rose so much higher than the ridge of the mountain that it was constantly visible to the inhabitants of the town of pasto. they described to us their astonishment when, on the th of february, , they observed the smoke disappear in an instant, whilst no shock whatever was felt. at that very moment, sixty-five leagues southward, between chimborazo, tunguragua, and the altar (capac-urcu), the town of riobamba was overthrown by the most terrible earthquake on record. is it possible to doubt, from this coincidence of phenomena, that the vapours issuing from the small apertures or ventanillas of the volcano of pasto had an influence on the pressure of those elastic fluids which convulsed the earth in the kingdom of quito, and destroyed in a few minutes thirty or forty thousand inhabitants? to explain these great effects of volcanic reactions, and to prove that the group or system of the volcanoes of the west india islands may sometimes shake the continent, i have cited the cordillera of the andes. geological reasoning can be supported only by the analogy of facts which are recent, and consequently well authenticated: and in what other region of the globe could we find greater and more varied volcanic phenomena than in that double chain of mountains heaved up by fire? in that land where nature has covered every mountain and every valley with her marvels? if we consider a burning crater only as an isolated phenomenon, if we be satisfied with merely examining the mass of stony substances which it has thrown up, the volcanic action at the surface of the globe will appear neither very powerful nor very extensive. but the image of this action becomes enlarged in the mind when we study the relations which link together volcanoes of the same group; for instance, those of naples and sicily, of the canary islands,* of the azores, of the caribbee islands of mexico, of guatimala, and of the table-land of quito; when we examine either the reactions of these different systems of volcanoes on one another, or the distance at which, by subterranean communication, they simultaneously convulse the earth. (i have already observed (chapter . ) that the whole group of the canary islands rises, as we may say, above one and the same submarine volcano. since the sixteenth century, the fire of this volcano has burst forth alternately in palma, teneriffe, and lancerote. auvergne presents a whole system of volcanoes, the action of which has now ceased; but in the middle of a system of active volcanoes, for instance, in that of quito, we must not consider as an extinguished volcano a mountain, the crater of which is obstructed, and through which the subterraneous fire has not issued for ages. etna, the aeolian isles, vesuvius, and epomeo; the peak of teyde, palma, and lancerote; st. michael, la caldiera of fayal, and pico; st. vincent, st. lucia, and guadaloupe; orizava, popocatepetl, jorullo, and la colima; bombacho, the volcano of grenada, telica, momotombo, isalco, and the volcano of guatimala; cotopaxi, tunguragua, pichincha, antisana, and sangai, belong to the same system of burning volcanoes; they are generally ranged in rows, as if they had issued from a crevice, or vein not filled up; and, it is very remarkable, that their position is in some parts in the general direction of the cordilleras, and in others in a contrary direction.) the study of volcanoes may be divided into two distinct branches; one, simply mineralogical, is directed to the examination of the stony strata, altered or produced by the action of fire; from the formation of the trachytes or trap-porphyries, of basalts, phonolites, and dolerites, to the most recent lavas: the other branch, less accessible and more neglected, comprehends the physical relations which link volcanoes together, the influence of one volcanic system on another, the connection existing between the action of burning mountains and the commotions which agitate the earth at great distances, and during long intervals, in the same direction. this study cannot progress till the various epochs of simultaneous action, the direction, the extent, and the force of the convulsions are carefully noted; till we have attentively observed their progressive advance to regions which they had not previously reached; and the coincidence between distant volcanic eruptions and those noises which the inhabitants of the andes very expressively term subterraneous thunders, or roarings.* (* bramidos y truenos subterraneos.) all these objects are comprehended in the domain of the history of nature. though the narrow circle within which all certain traditions are confined, does not present any of those general revolutions which have heaved up the cordilleras and buried myriads of pelagian animals; yet nature, acting under our eyes, nevertheless exhibits violent though partial changes, the study of which may throw light on the most remote epochs. in the interior of the earth those mysterious powers exist, the effects of which are manifested at the surface by the production of vapours, of incandescent scoriae, of new volcanic rocks and thermal springs, by the appearance of new islands and mountains, by commotions propagated with the rapidity of an electric shock, finally by those subterranean thunders,* heard during whole months, without shaking the earth, in regions far distant from active volcanoes. (* in the town of guanaxuato, in mexico, these thunders lasted from the th of january till the th of february, . guanaxuato is situated forty leagues north of the volcano of jorullo, and sixty leagues north west of the volcano of popocatepetl. in places nearer these two volcanoes, three leagues distant from guanaxuato, the subterranean thunders were not heard. the noise was circumscribed within a very narrow space, in the region of a primitive schist, which approaches a transition-schist, containing the richest silver mines of the known world, and on which rest trap-porphyries, slates, and diabasis (grunstein.)) in proportion as equinoctial america shall increase in culture and population, and the system of volcanoes of the central table-land of mexico, of the caribbee islands, of popayan, of los pastos, and quito, shall be more attentively observed, the connection of eruptions and of earthquakes, which precede and sometimes accompany those eruptions, will be more generally recognized. the volcanoes just mentioned, particularly those of the andes, which rise above the enormous height of two thousand five hundred toises, present great advantages for observation. the periods of their eruptions are singularly regular. they remain thirty or forty years without emitting scoriae, ashes, or even vapours. i could not perceive the smallest trace of smoke on the summit of tunguragua or cotopaxi. a gust of vapour issuing from the crater of mount vesuvius scarcely attracts the attention of the inhabitants of naples, accustomed to the movements of that little volcano, which throws out scoriae sometimes during two or three years successively. thence it becomes difficult to judge whether the emission of scoriae may have been more frequent at the time when an earthquake has been felt in the apennines. on the ridge of the cordilleras everything assumes a more decided character. an eruption of ashes, which lasts only a few minutes, is often followed by a calm of ten years. in such circumstances it is easy to mark the periods, and to observe the coincidence of phenomena. if, as there appears to be little reason to doubt, that the destruction of cumana in , and of caracas in , indicate the influence of the volcanoes of the west india islands* on the commotions felt on the coasts of terra firma, it may be desirable, before we close this chapter, to take a cursory view of this mediterranean archipelago. (* the following is the series of the phenomena:-- th of september, . eruption in the west india islands. (volcano of guadaloupe). november, . the volcano of pasto began to emit smoke. th of december, . destruction of cumana. th of february, . destruction of riobamba. th of january, . appearance of sabrina island, in the azores. the island enlarged very considerably on the th of june, . may, . commencement of the earthquakes in the island of st. vincent, which lasted till may . th of december, . commencement of the commotions in the valley of the mississippi and the ohio, which lasted till . december, . earthquake at caracas. th of march, . destruction of caracas. earthquakes, which continued till . th of april, . eruption of the volcano in st. vincent; and the same day subterranean noises at caracas, and on the banks of the apure.) the volcanic islands form one-fifth of that great arc extending from the coast of paria to the peninsula of florida. running from south to north, they close the caribbean sea on the eastern side, while the greater west india islands appear like the remains of a group of primitive mountains, the summit of which seems to have been between cape abacou, point morant, and the copper mountains, in that part where the islands of st. domingo, cuba, and jamaica, are nearest to each other. considering the basin of the atlantic as an immense valley* which separates the two continents, and where, from degrees south to degrees north, the salient angles (brazil and senegambia) correspond to the receding angles (the gulf of guinea and the caribbean sea), we are led to think that the latter sea owes its formation to the action of currents, which, like the current of rotation now existing, have flowed from east to west; and have given the southern coast of porto rico, st. domingo, and the island of cuba their uniform configuration. (* the valley is narrowest ( leagues) between cape st. roque and sierra leone. proceeding toward the north along the coasts of the new continent, from its pyramidal extremity, or the straits of magellan, we imagine we recognise the effects of a repulsion directed first toward the north-east, then toward the north-west, and finally again to the north-east.) this supposition of an oceanic irruption has been the source of two other hypotheses on the origin of the smaller west india islands. some geologists admit that the uninterrupted chain of islands from trinidad to florida exhibits the remains of an ancient chain of mountains. they connect this chain sometimes with the granite of french guiana, sometimes with the calcareous mountains of pari. others, struck with the difference of geological constitution between the primitive mountains of the greater and the volcanic cones of the lesser antilles, consider the latter as having risen from the bottom of the sea. if we recollect that volcanic upheavings, when they take place through elongated crevices, usually take a straight direction, we shall find it difficult to judge from the disposition of the craters alone, whether the volcanoes have belonged to the same chain, or have always been isolated. supposing an irruption of the ocean to take place either into the eastern part of the island of java* (* raffles, history of java, , pages - . the principal line of the volcanoes of java, on a distance of leagues, runs from west to east, through the mountains of gagak, gede, tankuban-prahu, ungarang merapi, lawu, wilis, arjuna, dasar, and tashem.) or into the cordilleras of guatimala and nicaragua, where so many burning mountains form but one chain, that chain would be divided into several islands, and would perfectly resemble the caribbean archipelago. the union of primitive formations and volcanic rocks in the same range of mountain is not extraordinary; it is very distinctly seen in my geological sections of the cordillera of the andes. the trachytes and basalts of popayan are separated from the system of the volcanoes of quito by the mica-slates of almaguer; the volcanoes of quito from the trachytes of assuay by the gneiss of condorasta and guasunto. there does not exist a real chain of mountains running south-east and north-west from oyapoc to the mouths of the orinoco, and of which the smaller west india islands might be a northern prolongation. the granites of guiana, as well as the hornblende-slates, which i saw near angostura, on the banks of the lower orinoco, belong to the mountains of pacaraimo and of parime, stretching from west to east, * (from the cataracts of atures towards the essequibo river. this chain of pacaraimo divides the waters of the carony from those of the rio parime, or rio de aguas blancas.) in the interior of the continent, and not in a direction parallel with the coast, between the mouths of the river amazon and the orinoco. but though we find no chain of mountains at the north-east extremity of terra firma, having the same direction as the archipelago of the smaller west india islands, it does not therefore follow that the volcanic mountains of the archipelago may not have belonged originally to the continent, and formed a part of the littoral chain of caracas and cumana.* (* among many such examples which the structure of the globe displays, we shall mention only the inflexion at a right angle formed by the higher alps towards the maritime alps, in europe; and the belour-tagh, which joins transversely the mouz-tagh and the himalaya, in asia. amid the prejudices which impede the progress of mineralogical geography, we may reckon, st, the supposition of a perfect uniformity of direction in the chains of mountains; nd, the hypothesis of the continuity of all chains; rd, the supposition that the highest summits determine the direction of a central chain; th, the idea that, in all places where great rivers take rise, we may suppose the existence of great tablelands, or very high mountains.) in opposing the objections of some celebrated naturalists, i am far from maintaining the ancient contiguity of all the smaller west india islands. i am rather inclined to consider them as islands heaved up by fire, and ranged in that regular line, of which we find striking examples in so many volcanic hills in auvergne, in mexico, and in peru. the geological constitution of the archipelago appears, from the little we know respecting it, to be very similar to that of the azores and the canary islands. primitive formations are nowhere seen above ground; we find only what belongs unquestionably to volcanoes: feldspar-lava, dolerite, basalt, conglomerated scoriae, tufa, and pumice-stone. among the limestone formations we must distinguish those which are essentially subordinate to volcanic tufas* from those which appear to be the work of madrepores and other zoophytes. (* we have noticed some of the above, following von buch, at lancerote, and at fortaventura, in the system of the canary islands. among the smaller islands of the west indies, the following islets are entirely calcareous, according to m. cortes: mariegalante, la desirade, the grande terre of guadaloupe, and the grenadillas. according to the observations of that naturalist, curacoa and buenos ayres present only calcareous formations. m. cortes divides the west india islands into, st, those containing at once primitive, secondary, and volcanic formations, like the greater islands; nd, those entirely calcareous, (or at least so considered) as mariegalante and curacoa; rd, those at once volcanic and calcareous, as antigua, st. bartholomew, st. martin, and st. thomas; th, those which have volcanic rocks only, as st. vincent, st. lucia, and st. eustache.) the latter, according to m. moreau de jonnes, seem to lie on shoals of a volcanic nature. those mountains, which present traces of the action of fire more or less recent, and some of which reach nearly nine hundred toises of elevation, are all situated on the western skirt of the smaller west india islands.* (* journal des mines, tome page . in order to exhibit in one point of view the whole system of the volcanoes of the smaller west india islands, i will here trace the direction of the islands from south to north.--grenada, an ancient crater, filled with water; boiling springs; basalts between st. george and goave.--st. vincent, a burning volcano.--st. lucia, a very active solfatara, named oualibou, two or three hundred toises high; jets of hot water, by which small basins are periodically filled.--martinique, three great extinguished volcanoes; vauclin, the paps of carbet, which are perhaps the most elevated summits of the smaller islands, and montagne pelee. (the height of this last mountain is probably toises; according to leblond it is toises; according to dupuget, toises. between vauclin and the feldspar-lavas of the paps of carbet is found, as m. moreau de jonnes asserts, in a neck of land, a region of early basalt called la roche carree). thermal waters of precheur and lameutin.--dominica, completely volcanic.--guadaloupe, an active volcano, the height of which, according to leboucher, is toises; according to amie, toises.--montserrat, a solfatara; fine porphyritic lavas with large crystals of feldspar and hornblende near galloway, according to mr. nugent.--nevis, a solfatara.--st. christopher's, a solfatara at mount misery.--st. eustache, a crater of an extinguished volcano, surrounded by pumice-stone. (trinidad, which is traversed by a chain of primitive slate, appears to have anciently formed a part of the littoral chain of cumana, and not of the system of the mountains of the caribbee islands.)) each island is not the effect of one single heaving-up: most of them appear to consist of isolated masses which have been progressively united together. the matter has not been emitted from one crater, but from several; so that a single island of small extent contains a whole system of volcanoes, regions purely basaltic, and others covered with recent lavas. the volcanoes still burning are those of st. vincent, st. lucia, and guadaloupe. the first threw out lava in and ; in the second there is a continual formation of sulphur by the condensation of vapours, which issue from the crevices of an ancient crater. the last eruption of the volcano of guadaloupe took place in . the solfatara of st. christopher's was still burning in . at martinique, vauclin, montagne pelee, and the crater surrounded by the five paps of carbet, must be considered as three extinguished volcanoes. the effects of thunder have been often confounded in that place with subterranean fire. no good observation has confirmed the supposed eruption of the nd of january, . the group of volcanoes in the caribbee islands resembles that of the volcanoes of quito and los pastos; craters with which the subterranean fire does not appear to communicate are ranged on the same line with burning craters, and alternate with them. notwithstanding the intimate connection manifested in the action of the volcanoes of the smaller west india islands and the earthquakes of terra firma, it often happens that shocks felt in the volcanic archipelago are not propagated to the island of trinidad, or to the coasts of caracas and cumana. this phenomenon is in no way surprising: even in the caribbees the commotions are often confined to one place. the great eruption of the volcano in st. vincent's did not occasion an earthquake at martinique or guadaloupe. loud explosions were heard there as well as at venezuela, but the ground was not convulsed. these explosions must not be confounded with the rolling noise which everywhere precedes the slightest commotions; they are often heard on the banks of the orinoco, and (as we were assured by persons living on the spot) between the rio arauca and cuchivero. father morello relates that at the mission of cabruta the subterranean noise so much resembles discharges of small cannon (pedreros) that it has seemed as if a battle were being fought at a distance. on the st of october, , the day of the terrible earthquake which desolated the province of new andalusia, the ground was simultaneously shaken at cumana, at caracas, at maracaybo, and on the banks of the casanare, the meta, the orinoco, and the ventuario. father gili has described these commotions at the mission of encaramada, a country entirely granitic, where they were accompanied by loud explosions. great fallings-in of the earth took place in the mountain paurari, and near the rock aravacoto a small island disappeared in the orinoco. the undulatory motion continued during a whole hour. this seemed the first signal of those violent commotions which shook the coasts of cumana and cariaco for more than ten months. it might be supposed that men living in woods, with no other shelter than huts of reeds and palm-leaves, could have little to dread from earthquakes. but at erevato and caura, where these phenomena are of rare occurrence, they terrify the indians, frighten the beasts of the forests, and impel the crocodiles to quit the waters for the shore. nearer the sea, where shocks are frequent, far from being dreaded by the inhabitants, they are regarded with satisfaction as the prognostics of a wet and fertile year. in this dissertation on the earthquakes of terra firma and on the volcanoes of the neighbouring archipelago of the west india islands, i have pursued the plan of first relating a number of particular facts, and then considering them in one general point of view. everything announces in the interior of the globe the operation of active powers, which, by mutual reaction, balance and modify one another. the greater our ignorance of the causes of these undulatory movements, these evolutions of heat, these formations of elastic fluids, the more it becomes the duty of persons who apply themselves to the study of physical science to examine the relations which these phenomena so uniformly present at great distances apart. it is only by considering these various relations under a general point of view, and tracing them over a great extent of the surface of the globe, through formations of rocks the most different, that we are led to abandon the supposition of trifling local causes, strata of pyrites, or of ignited coal.* (* see "views of nature"--on the structure and action of volcanoes in different parts of the world, page (bohn's edition); also "cosmos" pages - (bohn's edition).) the following is the series of phenomena remarked on the northern coasts of cumana, nueva barcelona, and caracas; and presumed to be connected with the causes which produce earthquakes and eruptions of lava. we shall begin with the most eastern extremity, the island of trinidad; which seems rather to belong to the shore of the continent than to the system of the mountains of the west india islands. . the pit which throws up asphaltum in the bay of mayaro, on the eastern coast of the island of trinidad, southward of point guataro. this is the mine of chapapote or mineral tar of the country. i was assured that in the months of march and june the eruptions are often attended with violent explosions, smoke, and flames. almost on the same parallel, and also in the sea, but westward of the island (near punta de la brea, and to the south of the port of naparaimo), we find a similar vent. on the neighbouring coast, in a clayey ground, appears the celebrated lake of asphaltum (laguna de la brea), a marsh, the waters of which have the same temperature as the atmosphere. the small cones situated at the south-western extremity of the island, between point icacos and the rio erin, appear to have some analogy with the volcanoes of air and mud which i met with at turbaco in the kingdom of new grenada. i mention these situations of asphaltum on account of the remarkable circumstances peculiar to them in these regions; for i am not unaware that naphtha, petroleum, and asphaltum are found equally in volcanic and secondary regions,* and even more frequently in the latter. (* the inflammable emanations of pietra mala, (consisting of hydrogen gas containing naphtha in a state of suspension) issue from the alpine limestone, which may be traced from covigliano to raticofa, and which lies on ancient sandstone near scarica l'asino. under this sandstone (old red sandstone) we find black transition limestone and the grauwack (quartzose psammite) of florence.) petroleum is found floating on the sea thirty leagues north of trinidad, around the island of grenada, which contains an extinguished crater and basalts. . hot springs of irapa, at the north-eastern extremity of new andalusia, between rio caribe, soro, and yaguarapayo. . air-volcano, or salce, of cumacatar, to the south of san jose and carupano, near the northern coast of the continent, between la montana de paria and the town of cariaco. almost constant explosions are felt in a clayey soil, which is affirmed to be impregnated with sulphur. hot sulphureous waters gush out with such violence that the ground is agitated by very sensible shocks. it is said that flames have been frequently seen issuing out since the great earthquake of . these facts are well worthy of being examined. . petroleum-spring of the buen pastor, near rio areo. large masses of sulphur have been found in clayey soils at guayuta, as in the valley of san bonifacio, and near the junction of the rio pao with the orinoco. . the hot waters (aguas calientes) south of the rio azul, and the hollow ground of cariaco, which, at the time of the great earthquake of cumana, threw up sulphuretted water and viscous petroleum. . hot waters of the gulf of cariaco. . petroleum-spring in the same gulf, near maniquarez. it issues from mica-slate. . flames issuing from the earth, near cumana, on the banks of the manzanares, and at mariguitar, on the southern coast of the gulf of cariaco, at the time of the great earthquake of . . igneous phenomena of the mountain of cuchivano, near cumanacoa. . petroleum-spring gushing from a shoal to the north of the caracas islands. the smell of this spring warns ships of the danger of this shoal, on which there is only one fathom of water. . thermal springs of the mountain of the brigantine, near nueva barcelona. temperature . degrees (centigrade). . thermal springs of provisor, near san diego, in the province of new barcelona. . thermal springs of onoto, between turmero and maracay, in the valleys of aragua, west of caracas. . thermal springs of mariara, in the same valleys. temperature . degrees. . thermal springs of las trincheras, between porto cabello and valencia, issuing from granite like those of mariara, and forming a river of warm water (rio de aguas calientes). temperature . degrees. . boiling springs of the sierra nevada of merida. . aperture of mena, on the borders of lake maracaybo. it throws up asphaltum, and is said to emit gaseous emanations, which ignite spontaneously, and are seen at a great distance. these are the springs of petroleum and of thermal waters, the igneous meteors, and the ejections of muddy substances attended with explosions, of which i acquired a knowledge in the vast provinces of venezuela, whilst travelling over a space of two hundred leagues from east to west. these various phenomena have occasioned great excitement among the inhabitants since the catastrophes of and : yet they present nothing which constitutes a volcano, in the sense hitherto attributed to that word. if the apertures, which throw up vapours and water with violent noise, be sometimes called volcancitos, it is only by such of the inhabitants as persuade themselves that volcanoes must necessarily exist in countries so frequently exposed to earthquakes. advancing from the burning crater of st. vincent in the directions of south, west and south-west, first by the chain of the caribbee islands, then by the littoral chain of cumana and venezuela, and finally by the cordilleras of new grenada, along a distance of three hundred and eighty leagues, we find no active volcano before we arrive at purace, near popayan. the total absence of apertures, through which melted substances can issue, in that part of the continent, which stretches eastward of the cordillera of the andes, and eastward of the rocky mountains, is a most remarkable geological fact. in this chapter we have examined the great commotions which from time to time convulse the stony crust of the globe, and scatter desolation in regions favoured by the most precious gifts of nature. an uninterrupted calm prevails in the upper atmosphere; but, to use an expression of franklin, more ingenious than accurate, thunder often rolls in the subterranean atmosphere, amidst that mixture of elastic fluids, the impetuous movements of which are frequently felt at the surface of the earth. the destruction of so many populous cities presents a picture of the greatest calamities which afflict mankind. a people struggling for independence are suddenly exposed to the want of subsistence, and of all the necessaries of life. famished and without shelter, the inhabitants are dispersed through the country, and numbers who have escaped from the ruin of their dwellings are swept away by disease. far from strengthening mutual confidence among the citizens, the feeling of misfortune destroys it; physical calamities augment civil discord; nor does the aspect of a country bathed in tears and blood appease the fury of the victorious party. after the recital of so many calamities, the mind is soothed by turning to consolatory remembrances. when the great catastrophe of caracas was known in the united states, the congress, assembled at washington, unanimously decreed that five ships laden with flour should be sent to the coast of venezuela; their cargoes to be distributed among the most needy of the inhabitants. the generous contribution was received with the warmest gratitude; and this solemn act of a free people, this mark of national interest, of which the advanced civilization of the old world affords but few examples, seemed to be a valuable pledge of the mutual sympathy which ought for ever to unite the nations of north and south america. chapter . . departure from caracas. mountains of san pedro and of los teques. la victoria. valleys of aragua. to take the shortest road from caracas to the banks of the orinoco, we should have crossed the southern chain of mountains between baruta, salamanca, and the savannahs of ocumare, passed over the steppes or llanos of orituco, and embarked at cabruta, near the mouth of the rio guarico. but this direct route would have deprived us of the opportunity of surveying the valleys of aragua, which are the finest and most cultivated portion of the province; of taking the level of an important part of the chain of the coast by means of the barometer; and of descending the rio apure as far as its junction with the orinoco. a traveller who has the intention of studying the configuration and natural productions of a country is not guided by distances, but by the peculiar interest attached to the regions he may traverse. this powerful motive led us to the mountains of los teques, to the hot springs of mariara, to the fertile banks of the lake of valencia, and through the immense savannahs of calabozo to san fernando de apure, in the eastern part of the province of varinas. having determined on this route, our first direction was westward, then southward, and finally to east-south-east, so that we might enter the orinoco by the apure in latitude degrees minutes seconds. on the day on which we quitted the capital of venezuela, we reached the foot of the woody mountains which close the valley on the south-west. there we halted for the night, and on the following day we proceeded along the right bank of the rio guayra as far as the village of antimano, by a very fine road, partly scooped out of the rock. we passed by la vega and carapa. the church of la vega rises very picturesquely above a range of hills covered with thick vegetation. scattered houses surrounded with date-trees seem to denote the comfort of their inhabitants. a chain of low mountains separates the little river guayra from the valley of la pascua* (so celebrated in the history of the country) (* valley of cortes, or easter valley, so called because diego de losada, after having defeated the teques indians, and their cacique guaycaypuro, in the mountains of san pedro, spent the easter there in , before entering the valley of san francisco. in the latter place he founded the city of caracas.), and from the ancient gold-mines of baruta and oripoto. ascending in the direction of carapa, we enjoy once more the sight of the silla, which appears like an immense dome with a cliff on the side next the sea. this rounded summit, and the ridge of galipano crenated like a wall, are the only objects which in this basin of gneiss and mica-slate impress a peculiar character on the landscape. the other mountains have a uniform and monotonous aspect. a little before reaching the village of antimano we observed on the right a very curious geological phenomenon. in hollowing the new road out of the rock, two large veins of gneiss were discovered in the mica-slate. they are nearly perpendicular, intersecting all the mica-slate strata, and are from six to eight toises thick. these veins contain not fragments, but balls or spheres of granular diabasis,* formed of concentric layers. (* ur-grunstein. i remember having seen similar balls filling a vein in transition-slate, near the castle of schauenstein in the margravate of bayreuth. i sent several balls from antimano to the collection of the king of spain at madrid.) these balls are composed of lamellar feldspar and hornblende closely commingled. the feldspar approximates sometimes to vitreous feldspar when disseminated in very thin laminae in a mass of granular diabasis, decomposed, and emitting a strong argillaceous smell. the diameter of the spheres is very unequal, sometimes four or eight inches, sometimes three or four feet; their nucleus, which is more dense, is without concentric layers, and of a very dark green hue, inclining to black. i could not perceive any mica in them; but, what is very remarkable, i found great quantities of disseminated garnets. these garnets are of a very fine red, and are found in the grunstein only. they are neither in the gneiss, which serves as a cement to the balls, nor in the mica-slate, which the veins traverse. the gneiss, the constituent parts of which are in a state of considerable disintegration, contains large crystals of feldspar; and, though it forms the body of the vein in the mica-slate, it is itself traversed by threads of quartz two inches thick, and of very recent formation. the aspect of this phenomenon is very curious: it appears as if cannon-balls were embedded in a wall of rock. i also thought i recognized in these same regions, in the montana de avila, and at cabo blanco, east of la guayra, a granular diabasis, mixed with a small quantity of quartz and pyrites, and destitute of garnets, not in veins, but in subordinate strata in the mica-slate. this position is unquestionably to be found in europe in primitive mountains; but in general the granular diabasis is more frequently connected with the system of transition rocks, especially with a schist (ubergangs-thonschiefer) abounding in beds of lydian stone strongly carburetted, of schistose jasper,* (kieselschiefer.) ampelites,* (alaunschiefer.) and black limestone. near antimano all the orchards were full of peach-trees loaded with blossom. this village, the valle, and the banks of the macarao, furnish great abundance of peaches, quinces, and other european fruits for the market of caracas. between antimano and ajuntas we crossed the rio guayra seventeen times. the road is very fatiguing; yet, instead of making a new one, it would perhaps be better to change the bed of the river, which loses a great quantity of water by the combined effects of filtration and evaporation. each sinuosity forms a marsh more or less extensive. this loss of water is to be regretted in a province, nearly all the cultivated portions of which are extremely dry. the rains are much less frequent and less violent in this place than in the interior of new andalusia, at cumanacoa, and on the banks of the guarapiche. many of the mountains of caracas enter the region of the clouds; but the strata of primitive rocks dip at an angle of or degrees, and generally to northwest, so that the waters are either lost in the interior of the earth, or gush out in copious springs not southward but northward of the mountains of the coast of niguatar, avila, and mariara. the rising of the gneiss and mica-slate strata to the south appears to me to explain in a considerable degree the extreme humidity of the coast. in the interior of the province we meet with portions of land, two or three leagues square, in which there are no springs; consequently sugar-cane, indigo, and coffee, grow only in places where running waters can be made to supply artificial irrigation during very dry weather. the early colonists imprudently destroyed the forests. evaporation is enormous on a stony soil surrounded with rocks, which radiate heat on every side. the mountains of the coast, like a wall, extending east and west from cape codera toward point tucacas, prevent the humid air of the shore (that is to say, those inferior strata of the atmosphere resting immediately on the sea, and dissolving the largest proportion of water) from penetrating to the islands. there are few openings, few ravines, which, like those of catia or of tipe, lead from the coast to the high longitudinal valleys, and there is no bed of a great river, no gulf allowing the sea to flow inland, spreading moisture by abundant evaporation. in the eighth and tenth degrees of latitude, in regions where the clouds do not, as it were, skim the surface of the soil, many trees are stripped of their leaves in the months of january and february; not by the sinking of the temperature as in europe, but because the air at this period, the most distant from the rainy season, nearly attains its maximum of dryness. only those plants which have very tough and glossy leaves resist this absence of humidity. beneath the fine sky of the tropics the traveller is struck with the almost hibernal aspect of the country; but the freshest verdure again appears when he reaches the banks of the orinoco, where another climate prevails; and the great forests preserve by their shade a certain quantity of moisture in the soil, by sheltering it from the devouring heat of the sun. beyond the small village of antimano the valley becomes much narrower. the river is bordered with lata, a fine gramineous plant with distich leaves, which sometimes reaches the height of thirty feet.* (* g. saccharoides.) every hut is surrounded with enormous trees of persea,* (* laurus persea (alligator pear).) at the foot of which the aristolochiae, paullinia, and other creepers vegetate. the neighbouring mountains, covered with forests, seem to spread humidity over the western extremity of the valley of caracas. we passed the night before our arrival at las ajuntas at a sugar-cane plantation. a square house (the hacienda or farm of don fernando key-munoz) contained nearly eighty negroes; they were lying on skins of oxen spread upon the ground. in each apartment of the house were four slaves: it looked like a barrack. a dozen fires were burning in the farm-yard, where people were employed in dressing food, and the noisy mirth of the blacks almost prevented us from sleeping. the clouds hindered me from observing the stars; the moon appeared only at intervals. the aspect of the landscape was dull and uniform, and all the surrounding hills were covered with aloes. workmen were employed at a small canal, intended for conveying the waters of the rio san pedro to the farm, at a height of more than seventy feet. according to a barometric calculation, the site of the hacienda is only fifty toises above the bed of the rio guayra at la noria, near caracas. the soil of these countries is found to be but little favourable to the cultivation of the coffee-tree, which in general is less productive in the valley of caracas than was imagined when the first plantations were made near chacao. the finest coffee-plantations are now found in the savannah of ocumare, near salamanca, and at rincon, in the mountainous countries of los mariches, san antonio hatillo, and los budares. the coffee of the three last mentioned places, situated eastward of caracas, is of a superior quality; but the trees bear a smaller quantity, which is attributed to the height of the spot and the coolness of the climate. the greater plantations of the province of venezuela (as aguacates, near valencia and rincon) yield in good years a produce of three thousand quintals. the extreme predilection entertained in this province for the culture of the coffee-tree is partly founded on the circumstance that the berry can be preserved during a great number of years; whereas, notwithstanding every possible care, cacao spoils in the warehouses after ten or twelve months. during the long dissensions of the european powers, at a time when spain was too weak to protect the commerce of her colonies, industry was directed in preference to productions of which the sale was less urgent, and could await the chances of political and commercial events. i remarked that in the coffee-plantations the nurseries are formed not so much by collecting together young plants, accidentally rising under trees which have yielded a crop, as by exposing the seeds of coffee to germination during five days, in heaps, between plantain leaves. these seeds are taken out of the pulp, but yet retaining a part of it adherent to them. when the seed has germinated it is sown, and it produces plants capable of bearing the heat of the sun better than those which spring up in the shade in coffee-plantations. in this country five thousand three hundred coffee-trees are generally planted in a fanega of ground, amounting to five thousand four hundred and seventy-six square toises. this land, if it be capable of artificial irrigation, costs five hundred piastres in the northern part of the province. the coffee-tree flowers only in the second year, and its flowering lasts only twenty-four hours. at this time the shrub has a charming appearance; and, when seen from afar, it appears covered with snow. the produce of the third year becomes very abundant. in plantations well weeded and watered, and recently cultivated, trees will bear sixteen, eighteen, and even twenty pounds of coffee. in general, however, more than a pound and a half or two pounds cannot be expected from each plant; and even this is superior to the mean produce of the west india islands. the coffee trees suffer much from rain at the time of flowering, as well as from the want of water for artificial irrigation, and also from a parasitic plant, a new species of loranthus, which clings to the branches. when, in plantations of eighty or a hundred thousand shrubs, we consider the immense quantity of organic matter contained in the pulpy berry of the coffee-tree, we may be astonished that no attempts have been made to extract a spirituous liquor from them.* (* the berries heaped together produce a vinous fermentation, during which a very pleasant alcoholic smell is emitted. placing, at caracas, the ripe fruit of the coffee-tree under an inverted jar, quite filled with water, and exposed to the rays of the sun, i remarked that no extrication of gas took place in the first twenty-four hours. after thirty-six hours the berries became brown, and yielded gas. a thermometer, enclosed in the jar in contact with the fruit, kept at night or degrees higher than the external air. in the space of eighty-seven hours, sixty berries, under various jars, yielded me from thirty-eight to forty cubic inches of a gas, which underwent no sensible diminution with nitrous gas. though a great quantity of carbonic acid had been absorbed by the water as it was produced, i still found . in the forty inches. the remainder, or . , was nitrogen. the carbonic acid had not been formed by the absorption of the atmospheric oxygen. that which is evolved from the berries of the coffee-tree slightly moistened, and placed in a phial with a glass stopple filled with air, contains alcohol in suspension; like the foul air which is formed in our cellars during the fermentation of must. on agitating the gas in contact with water, the latter acquires a decidedly alcoholic flavour. how many substances are perhaps contained in a state of suspension in those mixtures of carbonic acid and hydrogen, which are called deleterious miasmata, and which rise everywhere within the tropics, in marshy grounds, on the sea-shore, and in forests where the soil is strewed with dead leaves, rotten fruits, and putrefying insects.) if the troubles of st. domingo, the temporary rise in the price of colonial produce, and the emigration of french planters, were the first causes of the establishment of coffee plantations on the continent of america, in the island of cuba, and in jamaica; their produce has far more than compensated the deficiency of the exportation from the french west india islands. this produce has augmented in proportion to the population, the change of customs, and the increasing luxury of the nations of europe. the island of st. domingo exported, in , at the time of necker's administration, nearly seventy-six million pounds of coffee.* (* french pounds, containing grains. english pounds = french pounds; and spanish pounds = french pounds. the island of st. domingo was at that time, it must be remembered, a french colony.) tea could be cultivated as well as coffee in the mountainous parts of the provinces of caracas and cumana. every climate is there found rising in stages one above another; and this new culture would succeed there as well as in the southern hemisphere, where the government of brazil, protecting at the same time industry and religious toleration, suffered at once the introduction of chinese tea and of the dogmas of fo. it is not yet a century since the first coffee-trees were planted at surinam and in the west india islands, and already the produce of america amounts to fifteen millions of piastres, reckoning the quintal of coffee at fourteen piastres only. on the eighth of february we set out at sunrise, to cross the higuerote, a group of lofty mountains, separating the two longitudinal valleys of caracas and aragua. after passing, near las ajuntas, the junction of the two small rivers san pedro and macarao, which form the rio guayra, we ascended a steep hill to the table-land of la buenavista, where we saw a few lonely houses. the view extends on the north-west to the city of caracas, and on the south to the village of los teques. the country has a very wild aspect, and is thickly wooded. we had now gradually lost the plants of the valley of caracas.* (* the flora of caracas is characterized chiefly by the following plants, which grow between the heights of four hundred and six hundred toises. cipura martinicensis, panicum mieranthum, parthenium hysterophorus, vernonia odoratissima, (pevetera, with flowers having a delicious odour of heliotropium), tagetes caracasana, t. scoparia of lagasca (introduced by m. bonpland into the gardens of spain), croton hispidus, smilax scabriusculus, limnocharis humboldti, rich., equisetum ramosissimum, heteranthera alismoides, glycine punctata, hyptis plumeri, pavonia cancellata, cav., spermacoce rigida, crotalaria acutifolia, polygala nemorosa, stachytarpheta mutabilis, cardiospermum ulmaceum, amaranthus caracasanus, elephantopus strigosus, hydrolea mollis, alternanthera caracasana, eupatorium amydalinum, elytraria fasciculata, salvia fimbriata, angelonia salicaria, heliotropium strictum, convolvulus batarilla, rubus jamaicensis, datura arborea, dalea enneaphylla, buchnera rosea, salix humboldtiana, willd., theophrasta longifolia, tournefortia caracasana, inga cinerea, i. ligustrina, i. sapindioides, i. fastuosa, schwenkia patens, erythrina mitis. the most agreeable places for herborizing near caracas are the ravines of tacagua, tipe, cotecita, catoche, anauco, and chacaito.) we were eight hundred and thirty-five toises above the level of the ocean, which is almost the height of popayan; but the mean temperature of this place is probably only or degrees. the road over these mountains is much frequented; we met continually long files of mules and oxen; it is the great road leading from the capital to la victoria, and the valleys of aragua. this road is cut out of a talcose gneiss* in a state of decomposition. (* the direction of the strata of gneiss varies; it is either hor. . , dipping to the north-west or hor. . , dipping to the south-east.) a clayey soil mixed with spangles of mica covered the rock, to the depth of three feet. travellers suffer from the dust in winter, while in the rainy season the place is changed into a slough. on descending the table-land of buenavista, about fifty toises to the south-east, an abundant spring, gushing from the gneiss, forms several cascades surrounded with thick vegetation. the path leading to the spring is so steep that we could touch with our hands the tops of the arborescent ferns, the trunks of which reach a height of more than twenty-five feet. the surrounding rocks are covered with jungermannias and hypnoid mosses. the torrent, formed by the spring, and shaded with heliconias, uncovers, as it falls, the roots of the plumerias,* (* the red jasmine-tree, frangipanier of the french west india islands. the plumeria, so common in the gardens of the indians, has been very seldom found in a wild state. it is mixed here with the piper flagellare, the spadix of which sometimes reaches three feet long. with the new kind of fig-tree (which we have called ficus gigantea, because it frequently attains the height of a hundred feet), we find in the mountains of buenavista and of los teques, the ficus nymphaeifolia of the garden of schonbrunn, introduced into our hot-houses by m. bredemeyer. i am certain of the identity of the species found in the same places; but i doubt really whether it be really the f. nymphaeifolia of linnaeus, which is supposed to be a native of the east indies.) cupeys,* (* in the experiments i made at caracas, on the air which circulates in plants, i was struck with the fine appearance presented by the petioles and leaves of the clusia rosea, when cut open under water, and exposed to the rays of the sun. each trachea gives out a current of gas, purer by . than atmospheric air. the phenomenon ceases the moment the apparatus is placed in the shade. there is only a very slight disengagement of air at the two surfaces of the leaves of the clusia exposed to the sun without being cut open. the gas enclosed in the capsules of the cardiospermum vesicarium appeared to me to contain the same proportion of oxygen as the atmosphere, while that contained between the knots, in the hollow of the stalk, is generally less pure, containing only from . to . of oxygen. it is necessary to distinguish between the air circulating in the tracheae, and that which is stagnant in the great cavities of the stems and pericarps.) browneas, and ficus gigantea. this humid spot, though infested by serpents, presents a rich harvest to the botanist. the brownea, which the inhabitants call rosa del monte, or palo de cruz, bears four or five hundred purple flowers together in one thyrsus; each flower has invariably eleven stamina, and this majestic plant, the trunk of which grows to the height of fifty or sixty feet, is becoming rare, because its wood yields a highly valued charcoal. the soil is covered with pines (ananas), hemimeris, polygala, and melastomas. a climbing gramen* (* carice. see chapter .) with its light festoons unites trees, the presence of which attests the coolness of the climate of these mountains. such are the aralia capitata,* (* candelero. we found it also at la cumbre, at a height of toises.) the vismia caparosa, and the clethra fagifolia. among these plants, peculiar to the fine region of the arborescent ferns,* (* called by the inhabitants of the country region de los helechos.) some palm-trees rise in the openings, and some scattered groups of guarumo, or cecropia with silvery leaves. the trunks of the latter are not very thick, and are of a black colour towards the summit, as if burnt by the oxygen of the atmosphere. we are surprised to find so noble a tree, which has the port of the theophrasta and the palm-tree, bearing generally only eight or ten terminal leaves. the ants, which inhabit the trunk of the guarumo, or jarumo, and destroy its interior cells, seem to impede its growth. we had already made one herborization in the temperate mountains of the higuerote in the month of december, accompanying the capitan-general, senor de guevara, in an excursion with the intendant of the province to the valles de aragua. m. bonpland then found in the thickest part of the forest some plants of aguatire, the wood of which, celebrated for its fine red colour, will probably one day become an article of exportation to europe. it is the sickingia erythroxylon described by bredemeyer and willdenouw. descending the woody mountain of the higuerote to the south-west, we reached the small village of san pedro, situated in a basin where several valleys meet, and almost three hundred toises lower than the table-land of buenavista. plantain-trees, potatoes,* (* solanum tuberosum.) and coffee are cultivated together on this spot. the village is very small, and the church not yet finished. we met at an inn (pulperia) several european spaniards employed at the government tobacco farm. their dissatisfaction formed a strange contrast to our feelings. they were fatigued with their journey, and they vented their displeasure in complaints and maledictions on the wretched country, or to use their own phrase, estas tierras infelices, in which they were doomed to live. we, on the other hand, were enchanted with the wild scenery, the fertility of the soil, and the mildness of the climate. near san pedro, the talcose gneiss of buenavista passes into a mica-slate filled with garnets, and containing subordinate beds of serpentine. something analogous to this is met with at zoblitz in saxony. the serpentine, which is very pure and of a fine green, varied with spots of a lighter tint, often appears only superimposed on the mica-slate. i found in it a few garnets, but no metaloid diallage. the valley of san pedro, through which flows the river of the same name, separates two great masses of mountains, the higuerote and las cocuyzas. we ascended westward in the direction of the small farms of las lagunetos and garavatos. these are solitary houses, which serve as inns, and where the mule-drivers obtain their favourite beverage, the guarapo, or fermented juice of the sugar-cane: intoxication is very common among the indians who frequent this road. near garavatos there is a mica-slate rock of singular form; it is a ridge, or steep wall, crowned by a tower. we opened the barometer at the highest point of the mountain las cocuyzas,* (* absolute height toises.) and found ourselves almost at the same elevation as on the table-land of buenavista, which is scarcely ten toises higher. the prospect at las lagunetas is extensive, but rather uniform. this mountainous and uncultivated tract of ground between the sources of the guayra and the tuy is more than twenty-five square leagues in extent. we there found only one miserable village, that of los teques, south-east of san pedro. the soil is as it were furrowed by a multitude of valleys, the smallest of which, parallel with each other, terminate at right angles in the largest valleys. the back of the mountains presents an aspect as monotonous as the ravines; it has no pyramidal forms, no ridges, no steep declivities. i am inclined to think that the undulation of this ground, which is for the most part very gentle, is less owing to the nature of the rocks, (to the decomposition of the gneiss for instance), than to the long presence of the water and the action of currents. the limestone mountains of cumana present the same phenomenon north of tumiriquiri. from las lagunetas we descended into the valley of the rio tuy. this western slope of the mountains of los teques bears the name of las cocuyzas, and it is covered with two plants with agave leaves; the maguey of cocuyza, and the maquey of cocuy. the latter belongs to the genus yucca.* (* yucca acaulis, humb.) its sweet and fermented juice yields a spirit by distillation; and i have seen the young leaves of this plant eaten. the fibres of the full-grown leaves furnish cords of extraordinary strength.* (* at the clock of the cathedral of caracas, a cord of maguey, half an inch in diameter, sustained for fifteen years a weight of pounds.) leaving the mountains of the higuerote and los teques, we entered a highly cultivated country, covered with hamlets and villages; several of which would in europe be called towns. from east to west, on a line of twelve leagues in extent, we passed la victoria, san mateo, turmero, and maracay, containing together more than , inhabitants. the plains of the tuy may be considered as the eastern extremity of the valleys of aragua, extending from guigne, on the borders of the lake of valencia, as far as the foot of las cocuyzas. a barometrical measurement gave me toises for the absolute height of the valle del tuy, near the farm of manterola, and toises for that of the surface of the lake. the rio tuy, flowing from the mountains of las cocuyzas, runs first towards the west, then turning to the south and to the east, it takes its course along the high savannahs of ocumare, receives the waters of the valley of caracas, and reaches the sea near cape codera. it is the small portion of its basin in the westward direction which, geologically speaking, would seem to belong to the valley of aragua, if the hills of calcareous tufa, breaking the continuity of these valleys between consejo and la victoria, did not deserve some consideration. we shall here again remind the reader that the group of the mountains of los teques, eight hundred and fifty toises high, separates two longitudinal valleys, formed in gneiss, granite, and mica-slate. the most eastern of these valleys, containing the capital of caracas, is toises higher than the western valley, which may be considered as the centre of agricultural industry. having been for a long time accustomed to a moderate temperature, we found the plains of the tuy extremely hot, although the thermometer kept, in the day-time, between eleven in the morning and five in the afternoon, at only or degrees. the nights were delightfully cool, the temperature falling as low as . degrees. as the heat gradually abated, the air became more and more fragrant with the odour of flowers. we remarked above all the delicious perfume of the lirio hermoso,* (* pancratium undulatum.) a new species of pancratium, of which the flower, eight or nine inches long, adorns the banks of the rio tuy. we spent two very agreeable days at the plantation of don jose de manterola, who in his youth had accompanied the spanish embassy to russia. the farm is a fine plantation of sugar-canes; and the ground is as smooth as the bottom of a drained lake. the rio tuy winds through districts covered with plantains, and a little wood of hura crepitans, erythrina corallodendron, and fig-trees with nymphaea leaves. the bed of the river is formed of pebbles of quartz. i never met with more agreeable bathing than in the tuy. the water, as clear as crystal, preserves even during the day a temperature of . degrees; a considerable coolness for these climates, and for a height of three hundred toises; but the sources of the river are in the surrounding mountains. the house of the proprietor, situated on a hillock, of fifteen or twenty toises of elevation, is surrounded by the huts of the negroes. those who are married provide food for themselves; and here, as everywhere else in the valleys of aragua, a small spot of ground is allotted to them to cultivate. they labour on that ground on saturdays and sundays, the only days in the week on which they are free. they keep poultry, and sometimes even a pig. their masters boast of their happiness, as in the north of europe the great landholders love to descant upon the ease enjoyed by peasants who are attached to the glebe. on the day of our arrival we saw three fugitive negroes brought back; they were slaves newly purchased. i dreaded having to witness one of those punishments which, wherever slavery prevails, destroys all the charm of a country life. happily these blacks were treated with humanity. in this plantation, as in all those of the province of venezuela, three species of sugar-cane can be distinguished even at a distance by the colour of their leaves; the old creole sugar-cane, the otaheite cane, and the batavia cane. the first has a deep-green leaf, the stem not very thick, and the knots rather near together. this sugar-cane was the first introduced from india into sicily, the canary islands, and west indies. the second is of a lighter green; and its stem is higher, thicker, and more succulent. the whole plant exhibits a more luxuriant vegetation. we owe this plant to the voyages of bougainville, cook, and bligh. bougainville carried it to the mauritius, whence it passed to cayenne, martinique, and, since , to the rest of the west india islands. the sugar-cane of otaheite, called by the people of that island to, is one of the most important acquisitions for which colonial agriculture is indebted to the travels of naturalists. it yields not only one-third more juice than the creolian cane on the same space of ground; but from the thickness of its stem, and the tenacity of its ligneous fibres, it furnishes much more fuel. this last advantage is important in the west indies, where the destruction of the forests has long obliged the planters to use canes deprived of juice, to keep up the fire under the boilers. but for the knowledge of this new plant, together with the progress of agriculture on the continent of spanish america, and the introduction of the east india and java sugar, the prices of colonial produce in europe would have been much more sensibly affected by the revolutions of st. domingo, and the destruction of the great sugar plantations of that island. the otaheite sugar-cane was carried from the island of trinidad to caracas, under the name of cana solera, and it passed from caracas to cucuta and san gil in the kingdom of new grenada. in our days its cultivation during twenty-five years has almost entirely removed the apprehension at first entertained, that being transplanted to america, the cane would by degrees degenerate, and become as slender as the creole cane. the third species, the violet sugar-cane, called cana de batavia, or de guinea, is certainly indigenous in the island of java, where it is cultivated in preference in the districts of japara and pasuruan.* (* raffles history of java tome page .) its foliage is purple and very broad; and this cane is preferred in the province of caracas for rum. the tablones, or grounds planted with sugar-canes, are divided by hedges of a colossal gramen; the lata, or gynerium, with distich leaves. at the tuy, men were employed in finishing a dyke, to form a canal of irrigation. this enterprise had cost the proprietor seven thousand piastres for the expense of labour, and four thousand piastres for the costs of lawsuits in which he had become engaged with his neighbours. while the lawyers were disputing about a canal of which only one-half was finished, don jose de manterola began to doubt even of the possibility of carrying the plan into execution. i took the level of the ground with a lunette d'epreuve, on an artificial horizon, and found, that the dam had been constructed eight feet too low. what sums of money have i seen expended uselessly in the spanish colonies, for undertakings founded on erroneous levelling! the valley of the tuy has its 'gold mine,' like almost every part of america inhabited by whites, and backed by primitive mountains. i was assured, that in , foreign gold-gatherers had been engaged in picking up grains of that metal, and had established a place for washing the sand in the quebrada del oro. an overseer of a neighbouring plantation had followed these indications; and after his death, a waistcoat with gold buttons being found among his clothes, this gold, according to the logic of the people here, could only have proceeded from a vein, which the falling in of the earth had rendered invisible. in vain i objected, that i could not, by the mere view of the soil, without digging a large trench in the direction of the vein, judge of the existence of the mine; i was compelled to yield to the desire of my hosts. for twenty years past the overseer's waistcoat had been the subject of conversation in the country. gold extracted from the bosom of the earth is far more alluring in the eyes of the vulgar, than that which is the produce of agricultural industry, favoured by the fertility of the soil, and the mildness of the climate. north-west of the hacienda del tuy, in the northern range of the chain of the coast, we find a deep ravine, called the quebrada seca, because the torrent, by which it was formed, loses its waters through the crevices of the rock, before it reaches the extremity of the ravine. the whole of this mountainous country is covered with thick vegetation. we there found the same verdure as had charmed us by its freshness in the mountains of buenavista and las lagunetas, wherever the ground rises as high as the region of the clouds, and where the vapours of the sea have free access. in the plains, on the contrary, many trees are stripped of a part of their leaves during the winter; and when we descend into the valley of the tuy, we are struck with the almost hibernal aspect of the country. the dryness of the air is such that the hygrometer of deluc keeps day and night between and degrees. at a distance from the river scarcely any huras or piper-trees extend their foliage over thickets destitute of verdure. this seems owing to the dryness of the air, which attains its maximum in the month of february; and not, as the european planters assert, "to the seasons of spain, of which the empire extends as far as the torrid zone." it is only plants transported from one hemisphere to the other, which, in their organic functions, in the development of their leaves and flowers, still retain their affinity to a distant climate: faithful to their habits, they follow for a long time the periodical changes of their native hemisphere. in the province of venezuela the trees stripped of their foliage begin to renew their leaves nearly a month before the rainy season. it is probable, that at this period the electrical equilibrium of the air is already disturbed, and the atmosphere, although not yet clouded, becomes gradually more humid. the azure of the sky is paler, and the elevated regions are loaded with light vapours, uniformly diffused. this season may be considered as the awakening of nature; it is a spring which, according to the received language of the spanish colonies, proclaims the beginning of winter, and succeeds to the heats of summer.* (* that part of the year most abundant in rain is called winter; so that in terra firma, the season which begins by the winter solstice, is designated by the name of summer; and it is usual to hear, that it is winter on the mountains, at the time when summer prevails in the neighbouring plains.) indigo was formerly cultivated in the quebrada seca; but as the soil covered with vegetation cannot there concentrate so much heat as the plains and the bottom of the tuy valley receive and radiate, the cultivation of coffee has been substituted in its stead. as we advanced in the ravine we found the moisture increase. near the hato, at the northern extremity of the quebrada, a torrent rolls down over sloping beds of gneiss. an aqueduct was being formed there to convey the water to the plain. without irrigation, agriculture makes no progress in these climates. a tree of monstrous size fixed our attention.* (* hura crepitans.) it lay on the slope of the mountain, above the house of the hato. on the least dislodgment of the earth, its fall would have crushed the habitation which it shaded: it had therefore been burnt near its foot, and cut down in such a manner, that it fell between some enormous fig-trees, which prevented it from rolling into the ravine. we measured the fallen tree; and though its summit had been burnt, the length of its trunk was still one hundred and fifty-four feet.* (* french measure, nearly fifty metres.) it was eight feet in diameter near the roots, and four feet two inches at the upper extremity. our guides, less anxious than ourselves to measure the bulk of trees, continually pressed us to proceed onward and seek the 'gold mine.' this part of the ravine is little frequented, and is not uninteresting. we made the following observations on the geological constitution of the soil. at the entrance of the quebrada seca we remarked great masses of primitive saccharoidal limestone, tolerably fine grained, of a bluish tint, and traversed by veins of calcareous spar of dazzling whiteness. these calcareous masses must not be confounded with the very recent depositions of tufa, or carbonate of lime, which fill the plains of the tuy; they form beds of mica-slate, passing into talc-slate.* (* talkschiefer of werner, without garnets or serpentine; not eurite or weisstein. it is in the mountains of buenavista that the gneiss manifests a tendency to pass into eurite.) the primitive limestone often simply covers this latter rock in concordant stratification. very near the hato the talcose slate becomes entirely white, and contains small layers of soft and unctuous graphic ampelite.* (* zeichenschiefer.) some pieces, destitute of veins of quartz, are real granular plumbago, which might be of use in the arts. the aspect of the rock is very singular in those places where thin plates of black ampelite alternate with thin, sinuous, and satiny plates of a talcose slate as white as snow. it would seem as if the carbon and iron, which in other places colour the primitive rocks, are here concentrated in the subordinate strata. turning westward we reached at length the ravine of gold (quebrada del oro). on examining the slope of a hill, we could hardly recognize the vestige of a vein of quartz. the falling of the earth caused by the rains had changed the surface of the ground, and rendered it impossible to make any observation. great trees were growing in the places where the gold-washers had worked twenty years before. it is probable that the mica-slate contains here, as near goldcronach in franconia, and in salzburgh, auriferous veins; but how is it possible to judge whether they be worth the expense of being wrought, or whether the ore is only in nodules, and in the less abundance in proportion as it is rich? we made a long herborization in a thick forest, extending beyond the hato, and abounding in cedrelas, browneas, and fig-trees with nymphaea leaves. the trunks of these last are covered with very odoriferous plants of vanilla, which in general flower only in the month of april. we were here again struck with those ligneous excrescences, which in the form of ridges, or ribs, augment to the height of twenty feet above the ground, the thickness of the trunk of the fig-trees of america. i found trees twenty-two feet and a half in diameter near the roots. these ligneous ridges sometimes separate from the trunk at a height of eight feet, and are transformed into cylindrical roots two feet thick. the tree looks as if it were supported by buttresses. this scaffolding however does not penetrate very deep into the earth. the lateral roots wind at the surface of the ground, and if at twenty feet distance from the trunk they are cut with a hatchet, we see gushing out the milky juice of the fig-tree, which, when deprived of the vital influence of the organs of the tree, is altered and coagulates. what a wonderful combination of cells and vessels exist in these vegetable masses, in these gigantic trees of the torrid zone, which without interruption, perhaps during the space of a thousand years, prepare nutritious fluids, raise them to the height of one hundred and eighty feet, convey them down again to the ground, and conceal, beneath a rough and hard bark, under inanimate layers of ligneous matter, all the movements of organic life! i availed myself of the clearness of the nights, to observe at the plantation of tuy two emersions of the first and third satellites of jupiter. these two observations gave, according to the tables of delambre, longitude hours minutes seconds; and by the chronometer i found hours minutes seconds. during my stay in the valleys of the tuy and aragua the zodiacal light appeared almost every night with extraordinary brilliancy. i had perceived it for the first time between the tropics at caracas, on the th of january, after seven in the evening. the point of the pyramid was at the height of degrees. the light totally disappeared at hours minutes (apparent time), nearly hours minutes after sunset, without any diminution in the serenity of the sky. la caille, in his voyage to rio janeiro and the cape, was struck with the beautiful appearance displayed by the zodiacal light within the tropics, not so much on account of its less inclined position, as of the greater transparency of the air.* (* the great serenity of the air caused this phenomenon to be remarked, in , in the arid plains of persia.) it may appear singular, that childrey and dominic cassini, navigators who were well acquainted with the seas of the two indies, did not at a much earlier period direct the attention of scientific europe to this light, and its regular form and progress. until the middle of the eighteenth century mariners were little interested by anything not having immediate relation to the course of a ship, and the demands of navigation. however brilliant the zodiacal light in the dry valley of tuy, i have observed it more beautiful still at the back of the cordilleras of mexico, on the banks of the lake of tezcuco, eleven hundred and sixty toises above the surface of the ocean. in the month of january, , the light rose sometimes to more than degrees above the horizon. the milky way appeared to grow pale compared with the brilliancy of the zodiacal light; and if small, bluish, scattered clouds were accumulated toward the west, it seemed as if the moon were about to rise. i must here relate another very singular fact. on the th of january, and the th of february, , the intensity of the zodiacal light changed in a very perceptible manner, at intervals of two or three minutes. sometimes it was very faint, at others it surpassed the brilliancy of the milky way in sagittarius. the changes took place in the whole pyramid, especially toward the interior, far from the edges. during these variations of the zodiacal light, the hygrometer indicated considerable dryness. the stars of the fourth and fifth magnitude appeared constantly to the naked eye with the same degree of light. no stream of vapour was visible: nothing seemed to alter the transparency of the atmosphere. in other years i saw the zodiacal light augment in the southern hemisphere half an hour before its disappearance. cassini admitted "that the zodiacal light was feebler in certain years, and then returned to its former brilliancy." he thought that these slow changes were connected with "the same emanations which render the appearance of spots and faculae periodical on the solar disk." but this excellent observer does not mention those changes of intensity in the zodiacal light which i have several times remarked within the tropics, in the space of a few minutes. mairan asserts, that in france it is common enough to see the zodiacal light, in the months of february and march, mingling with a kind of aurora borealis, which he calls 'undecided,' and the nebulous matter of which spreads itself all around the horizon, or appears toward the west. i very much doubt, whether, in the observations i have been describing, there was any mixture of these two species of light. the variations in intensity took place at considerable altitudes; the light was white, and not coloured; steady, and not undulating. besides, the aurora borealis is so seldom visible within the tropics, that during five years, though almost constantly sleeping in the open air, and observing the heavens with unremitting attention, i never perceived the least traces of that phenomenon. i am rather inclined to think that the variations of the zodiacal light are not all appearances dependent on certain modifications in the state of our atmosphere. sometimes, during nights equally clear, i sought in vain for the zodiacal light, when, on the previous night, it had appeared with the greatest brilliancy. must we admit that emanations which reflect white light, and seem to have some analogy with the tails of comets, are less abundant at certain periods? researches on the zodiacal light have acquired a new degree of interest since geometricians have taught us that we are ignorant of the real causes of this phenomenon. the illustrious author of "la mecanique celeste" has shown that the solar atmosphere cannot reach even the planet mercury; and that it could not in any case display the lenticular form which has been attributed to the zodiacal light. we may also entertain the same doubts respecting the nature of this light, as with regard to that of the tails of comets. is it in fact a reflected or a direct light? we left the plantation of manterola on the th of february, at sunrise. the road runs along the smiling banks of the tuy; the morning was cool and humid, and the air seemed embalmed by the delicious odour of the pancratium undulatum, and other large liliaceous plants. in our way to la victoria, we passed the pretty village of mamon or of consejo, celebrated in the country for a miraculous image of the virgin. a little before we reached mamon, we stopped at a farm belonging to the family of monteras. a negress more than a hundred years old was seated before a small hut built of earth and reeds. her age was known because she was a creole slave. she seemed still to enjoy very good health. "i keep her in the sun" (la tengo al sol), said her grandson; "the heat keeps her alive." this appeared to us not a very agreeable mode of prolonging life, for the sun was darting his rays almost perpendicularly. the brown-skinned nations, blacks well seasoned, and indians, frequently attain a very advanced age in the torrid zone. a native of peru named hilario pari died at the extraordinary age of one hundred and forty-three years, after having been ninety years married. don francisco montera and his brother, a well-informed young priest, accompanied us with the view of conducting us to their house at la victoria. almost all the families with whom we had lived in friendship at caracas were assembled in the fine valleys of aragua, and they vied with each other in their efforts to render our stay agreeable. before we plunged into the forests of the orinoco, we enjoyed once more all the advantages which advanced civilization affords. the road from mamon to la victoria runs south and south-west. we soon lost sight of the river tuy, which, turning eastward, forms an elbow at the foot of the high mountains of guayraima. as we drew nearer to victoria the ground became smoother; it seemed like the bottom of a lake, the waters of which had been drained off. we might have fancied ourselves in the valley of hasli, in the canton of berne. the neighbouring hills, only one hundred and forty toises in height, are composed of calcareous tufa; but their abrupt declivities project like promontories on the plain. their form indicates the ancient shore of the lake. the eastern extremity of this valley is parched and uncultivated. no advantage has been derived from the ravines which water the neighbouring mountains; but fine cultivation is commencing in the proximity of the town. i say of the town, though in my time victoria was considered only as a village (pueblo). the environs of la victoria present a very remarkable agricultural aspect. the height of the cultivated ground is from two hundred and seventy to three hundred toises above the level of the ocean, and yet we there find fields of corn mingled with plantations of sugar-cane, coffee, and plantains. excepting the interior of the island of cuba,* (* the district of quatro villas.) we scarcely find elsewhere in the equinoctial regions european corn cultivated in large quantities in so low a region. the fine fields of wheat in mexico are between six hundred and twelve hundred toises of absolute elevation; and it is rare to see them descend to four hundred toises. we shall soon perceive that the produce of grain augments sensibly, from high latitudes towards the equator, with the mean temperature of the climate, in comparing spots of different elevations. the success of agriculture depends on the dryness of the air; on the rains distributed through different seasons, or accumulated in one season; on winds blowing constantly from the east; or bringing the cold air of the north into very low latitudes, as in the gulf of mexico; on mists, which for whole months diminish the intensity of the solar rays; in short, on a thousand local circumstances which have less influence on the mean temperature of the whole year than on the distribution of the same quantity of heat through the different parts of the year. it is a striking spectacle to see the grain of europe cultivated from the equator as far as lapland in the latitude of degrees, in regions where the mean heat is from to- degrees, in every place where the temperature of summer is above or degrees. we know the minimum of heat requisite to ripen wheat, barley, and oats; but we are less certain in respect to the maximum which these species of grain, accommodating as they are, can support. we are even ignorant of all the circumstances which favour the culture of corn within the tropics at very small heights. la victoria and the neighbouring village of san mateo yield an annual produce of four thousand quintals of wheat. it is sown in the month of december, and the harvest is reaped on the seventieth or seventy-fifth day. the grain is large, white, and abounding in gluten; its pellicle is thinner and not so hard as that of the wheat of the very cold table-lands of mexico. an acre* (* an arpent des eaux et forets, or legal acre of france, of which . = hectare. it is about / acre english.) near victoria generally yields from three thousand to three thousand two hundred pounds weight of wheat. the average produce is consequently here, as at buenos ayres, three or four times as much as that of northern countries. nearly sixteenfold of the quantity of seed is reaped; while, according to lavoisier, the surface of france yields on an average only five or six for one, or from one thousand to twelve hundred pounds per acre. notwithstanding this fecundity of the soil, and this happy influence of the climate, the culture of the sugar-cane is more productive in the valleys of aragua than that of corn. la victoria is traversed by the little river calanchas, running, not into the tuy, but into the rio aragua: it thence results that this fine country, producing at once sugar and corn, belongs to the basin of the lake of valencia, to a system of interior rivers not communicating with the sea. the quarter of the town west of the rio calanchas is called la otra banda; it is the most commercial part; merchandize is everywhere exhibited, and ranges of shops form the streets. two commercial roads pass through la victoria, that of valencia, or of porto cabello, and the road of villa de cura, or of the plains, called camino de los llanos. we here find more whites in proportion than at caracas. we visited at sunset the little hill of calvary, where the view is extremely fine and extensive. we discover on the west the lovely valleys of aragua, a vast space covered with gardens, cultivated fields, clumps of wild trees, farms, and hamlets. turning south and south-east, we see, extending as far as the eye can reach, the lofty mountains of la palma, guayraima, tiara, and guiripa, which conceal the immense plains or steppes of calabozo. this interior chain stretches westward along the lake of valencia, towards the villa de cura, the cuesta de yusma, and the denticulated mountains of guigne. it is very steep, and constantly covered with that light vapour which in hot climates gives a vivid blue tint to distant objects, and, far from concealing their outlines, marks them the more strongly. it is believed that among the mountains of the interior chain, that of guayraima reaches an elevation of twelve hundred toises. i found in the night of the eleventh of february the latitude of la victoria degrees minutes seconds, the magnetic dip . degrees, the intensity of the forces equal to oscillations in ten minutes of time, and the variation of the needle . degrees north-east. we proceeded slowly on our way by the villages of san mateo, turmero, and maracay, to the hacienda de cura, a fine plantation belonging to count tovar, where we arrived on the evening of the fourteenth of february. the valley, which gradually widens, is bordered with hills of calcareous tufa, called here tierra blanca. the scientific men of the country have made several attempts to calcine this earth, mistaking it for the porcelain earth proceeding from decomposed strata of feldspar. we stayed some hours with a very intelligent family, named ustariz, at concesion. their house, which contains a collection of choice books, stands on an eminence, and is surrounded by plantations of coffee and sugar-cane. a grove of balsam-trees (balsamo* (* amyris elata.)) gives coolness and shade to this spot. it was gratifying to observe the great number of scattered houses in the valley inhabited by freedmen. in the spanish colonies, the laws, the institutions, and the manners, are more favourable to the liberty of the negroes than in other european settlements. san mateo, turmero, and maracay, are charming villages, where everything denotes the comfort of the inhabitants. we seemed to be transported to the most industrious districts of catalonia. near san mateo we find the last fields of wheat, and the last mills with horizontal hydraulic wheels. a harvest of twenty for one was expected; and, as if that produce were but moderate, i was asked whether corn yielded more in prussia and in poland. by an error generally prevalent under the tropics, the produce of grain is supposed to degenerate in advancing towards the equator, and harvests are believed to be more abundant in northern climates. since calculations have been made on the progress of agriculture in the different zones, and on the temperatures under the influence of which corn will flourish, it has been found that, beyond the latitude of degrees, the produce of wheat is nowhere so considerable as on the northern coasts of africa, and on the table-lands of new grenada, peru, and mexico. without comparing the mean temperature of the whole year, but only the mean temperature of the season which embraces the corn cycle of vegetation, we find for three months of summer,* in the north of europe, from to degrees; in barbary and in egypt, from to degrees; within the tropics, between fourteen and three hundred toises of height, from to . degrees of the centigrade thermometer. (* the mean heat of the summers of scotland in the environs of edinburgh, (latitude degrees), is found again on the table-lands of new grenada, so rich in wheat, at toises of elevation, and at degrees north latitude. on the other hand, we find the mean temperature of the valleys of aragua, latitude degrees minutes, and of all the plains which are not very elevated in the torrid zone, in the summer temperature of naples and sicily, latitude to degrees. these figures indicate the situation of the isotheric lines (lines of the same summer heat), and not that of the isothermal lines (those of equal annual temperature). considering the quantity of heat received on the same spot of the globe during a whole year, the mean temperatures of the valleys of aragua, and the table-lands of new grenada, at and toises of elevation, correspond to the mean temperatures of the coasts at and degrees of latitude.) the fine harvests of egypt and of algiers, as well as those of the valleys of aragua and the interior of the island of cuba, sufficiently prove that the augmentation of heat is not prejudicial to the harvest of wheat and other alimentary grain, unless it be attended with an excess of drought or moisture. to this circumstance no doubt we must attribute the apparent anomalies sometimes observed within the tropics, in the lower limit of corn. we are astonished to see, eastward of the havannah, in the famous district of quatro villas, that this limit descends almost to the level of the ocean; whilst west of the havannah, on the slope of the mountains of mexico and xalapa, at six hundred and seventy-seven toises of height, the luxuriance of vegetation is such, that wheat does not form ears. at the beginning of the spanish conquest, the corn of europe was cultivated with success in several regions now supposed to be too hot, or too damp, for this branch of agriculture. the spaniards on their first removal to america were little accustomed to live on maize. they still adhered to their european habits. they did not calculate whether corn would be less profitable than coffee or cotton. they tried seeds of every kind, making experiments the more boldly because their reasonings were less founded on false theories. the province of carthagena, crossed by the chain of the mountains maria and guamoco, produced wheat till the sixteenth century. in the province of caracas, this culture is of very ancient date in the mountainous lands of tocuyo, quibor, and barquisimeto, which connect the littoral chain with the sierra nevada of merida. wheat is still successfully cultivated there, and the environs of the town of tocuyo alone export annually more than eight thousand quintals of excellent flour. but, though the province of caracas, in its vast extent, includes several spots very favourable to the cultivation of european corn, i believe that in general this branch of agriculture will never acquire any great importance there. the most temperate valleys are not sufficiently wide; they are not real table-lands; and their mean elevation above the level of the sea is not so considerable but that the inhabitants cannot fail to perceive that it is more their interest to establish plantations of coffee, than to cultivate corn. flour now comes to caracas either from spain or from the united states. the village of turmero is four leagues distant from san mateo. the road leads through plantations of sugar, indigo, cotton, and coffee. the regularity observable in the construction of the villages, reminded us that they all owe their origin to monks and missions. the streets are straight and parallel, crossing each other at right angles; and the church is invariably erected in the great square, situated in the centre of the village. the church of turmero is a fine edifice, but overloaded with architectural ornaments. since the missionaries have been replaced by vicars, the whites have mingled their habitations with those of the indians. the latter are gradually disappearing as a separate race; that is to say, they are represented in the general statement of the population by the mestizoes and the zamboes, whose numbers daily increase. i still found, however, four thousand tributary indians in the valleys of aragua. those of turmero and guacara are the most numerous. they are of small stature, but less squat than the chaymas; their eyes denote more vivacity and intelligence, owing less perhaps to a diversity in the race, than to a superior state of civilization. they work like freemen by the day. though active and laborious during the short time they allot to labour, yet what they earn in two months is spent in one week, in the purchase of strong liquors at the small inns, of which unhappily the numbers daily increase. we saw at turmero the remains of the assembled militia of the country, and their appearance alone sufficiently indicated that these valleys had enjoyed for ages undisturbed peace. the capitan-general, in order to give a new impulse to the military service, had ordered a grand review; and the battalion of turmero, in a mock fight, had fired on that of la victoria. our host, a lieutenant of the militia, was never weary of describing to us the danger of these manoeuvres, which seemed more burlesque than imposing. with what rapidity do nations, apparently the most pacific, acquire military habits! twelve years afterwards, those valleys of aragua, those peaceful plains of la victoria and turmero, the defile of cabrera, and the fertile banks of the lake of valencia, became the scenes of obstinate and sanguinary conflicts between the natives and the troops of the mother-country. south of turmero, a mass of limestone mountains advances into the plain, separating two fine sugar-plantations, guayavita and paja. the latter belongs to the family of count tovar, who have property in every part of the province. near guayavita, brown iron-ore has been discovered. to the north of turmero, a granitic summit (the chuao) rises in the cordillera of the coast, from the top of which we discern at once the sea and the lake of valencia. crossing this rocky ridge, which runs towards the west farther than the eye can reach, paths somewhat difficult lead to the rich plantations of cacao on the coast, to choroni, turiamo, and ocumare, noted alike for the fertility of the soil and the insalubrity of their climate. turmero, maracay, cura, guacara, every point of the valley of aragua, has its mountain-road, which terminates at one of the small ports on the coast. on quitting the village of turmero, we discover, at a league distant, an object, which appears at the horizon like a round hillock, or tumulus, covered with vegetation. it is neither a hill, nor a group of trees close to each other, but one single tree, the famous zamang del guayre, known throughout the province for the enormous extent of its branches, which form a hemispheric head five hundred and seventy-six feet in circumference. the zamang is a fine species of mimosa, and its tortuous branches are divided by bifurcation. its delicate and tender foliage was agreeably relieved on the azure of the sky. we stopped a long time under this vegetable roof. the trunk of the zamang del guayre,* (* the mimos of la guayre; zamang being the indian name for the genera mimosa, desmanthus, and acacia. the place where the tree is found is called el guayre.) which is found on the road from turmero to maracay, is only sixty feet high, and nine thick; but its real beauty consists in the form of its head. the branches extend like an immense umbrella, and bend toward the ground, from which they remain at a uniform distance of twelve or fifteen feet. the circumference of this head is so regular, that, having traced different diameters, i found them one hundred and ninety-two and one hundred and eighty-six feet. one side of the tree was entirely stripped of its foliage, owing to the drought; but on the other side there remained both leaves and flowers. tillandsias, lorantheae, cactus pitahaya, and other parasite plants, cover its branches, and crack the bark. the inhabitants of these villages, but particularly the indians, hold in veneration the zamang del guayre, which the first conquerors found almost in the same state in which it now remains. since it has been observed with attention, no change has appeared in its thickness or height. this zamang must be at least as old as the orotava dragon-tree. there is something solemn and majestic in the aspect of aged trees; and the violation of these monuments of nature is severely punished in countries destitute of monuments of art. we heard with satisfaction that the present proprietor of the zamang had brought an action against a cultivator who had been guilty of cutting off a branch. the cause was tried, and the tribunal condemned the offender. we find near turmero and the hacienda de cura other zamangs, having trunks larger than that of guayre, but their hemispherical heads are not of equal extent. the culture and population of the plains augment in the direction of cura and guacara, on the northern side of the lake. the valleys of aragua contain more than , inhabitants, on a space thirteen leagues in length, and two in width. this is a relative population of two thousand souls on a square league. the village or rather the small town of maracay was heretofore the centre of the indigo plantations, when this branch of colonial industry was in its greatest prosperity. the houses are all of masonry, and every court contains cocoa-trees, which rise above the habitations. the aspect of general wealth is still more striking at maracay, than at turmero. the anil, or indigo, of these provinces has always been considered in commerce as equal and sometimes superior to that of guatemala. the indigo plant impoverishes the soil, where it is cultivated during a long series of years, more than any other. the lands of maracay, tapatapa, and turmero, are looked upon as exhausted; and indeed the produce of indigo has been constantly decreasing. but in proportion as it has diminished in the valleys of aragua, it has increased in the province of varinas, and in the burning plains of cucuta, where, on the banks of the rio tachira, virgin land yields an abundant produce, of the richest colour. we arrived very late at maracay, and the persons to whom we were recommended were absent. the inhabitants perceiving our embarrassment, contended with each other in offering to lodge us, to place our instruments, and take care of our mules. it has been said a thousand times, but the traveller always feels desirous of repeating it again, that the spanish colonies are the land of hospitality; they are so even in those places where industry and commerce have diffused wealth and improvement. a family of canarians received us with the most amiable cordiality; an excellent repast was prepared, and everything was carefully avoided that might act as any restraint on us. the master of the house, don alexandro gonzales, was travelling on commercial business, and his young wife had lately had the happiness of becoming a mother. she was transported with joy when she heard that on our return from the rio negro we should proceed by the banks of the orinoco to angostura, where her husband was. we were to bear to him the tidings of the birth of his first child. in those countries, as among the ancients, travellers are regarded as the safest means of communication. there are indeed posts established, but they make such great circuits that private persons seldom entrust them with letters for the llanos or savannahs of the interior. the child was brought to us at the moment of our departure: we had seen him asleep at night, but it was deemed indispensable that we should see him awake in the morning. we promised to describe his features exactly to his father, but the sight of our books and instruments somewhat chilled the mother's confidence. she said "that in a long journey, amidst so many cares of another kind, we might well forget the colour of her child's eyes." on the road from maracay to the hacienda de cura we enjoyed from time to time the view of the lake of valencia. an arm of the granitic chain of the coast stretches southward into the plain. it is the promontory of portachuelo which would almost close the valley, were it not separated by a narrow defile from the rock of la cabrera. this place has acquired a sad celebrity in the late revolutionary wars of caracas; each party having obstinately disputed its possession, as opening the way to valencia, and to the llanos. la cabrera now forms a peninsula: not sixty years ago it was a rocky island in the lake, the waters of which gradually diminish. we spent seven very agreeable days at the hacienda da cura, in a small habitation surrounded by thickets. we lived after the manner of the rich in this country; we bathed twice, slept three times, and made three meals in the twenty-four hours. the temperature of the water of the lake is rather warm, being from twenty-four to twenty-five degrees; but there is another cool and delicious bathing-place at toma, under the shade of ceibas and large zamangs, in a torrent gushing from the granitic mountains of the rincon del diablo. in entering this bath, we had not to fear the sting of insects, but to guard against the little brown hairs which cover the pods of the dolichos pruriens. when these small hairs, well characterised by the name of picapica, stick to the body, they excite a violent irritation on the skin; the dart is felt, but the cause is unperceived. near cura we found all the people occupied in clearing the ground covered with mimosa, sterculia, and coccoloba excoriata, for the purpose of extending the cultivation of cotton. this product, which partly supplies the place of indigo, has succeeded so well during some years, that the cotton-tree now grows wild on the borders of the lake of valencia. we have found shrubs of eight or ten feet high entwined with bignonia and other ligneous creepers. the exportation of cotton from caracas, however, is yet of small importance. it amounted at an average at la guayra scarcely to three or four hundred thousand pounds in a year; but including all the ports of the capitania-general, it arose, on account of the flourishing culture of cariaco, nueva barcelona, and maracaybo, to more than , quintals. the cotton of the valleys of aragua is of fine quality, being inferior only to that of brazil; for it is preferred to that of carthagena, st. domingo, and the caribbee islands. the cultivation of cotton extends on one side of the lake from maracay to valencia; and on the other from guayca to guigue. the large plantations yield from sixty to seventy thousand pounds a year. during our stay at cura we made numerous excursions to the rocky islands (which rise in the midst of the lake of valencia,) to the warm springs of mariara, and to the lofty granitic mountain called el cucurucho de coco. a dangerous and narrow path leads to the port of turiamo and the celebrated cacao-plantations of the coast. in all these excursions we were agreeably surprised, not only at the progress of agriculture, but at the increase of a free laborious population, accustomed to toil, and too poor to rely on the assistance of slaves. white and mulatto farmers had everywhere small separate establishments. our host, whose father had a revenue of , piastres, possessed more lands than he could clear; he distributed them in the valleys of aragua among poor families who chose to apply themselves to the cultivation of cotton. he endeavoured to surround his ample plantations with freemen, who, working as they chose, either in their own land or in the neighbouring plantations, supplied him with day-labourers at the time of harvest. nobly occupied on the means best adapted gradually to extinguish the slavery of the blacks in these provinces, count tovar flattered himself with the double hope of rendering slaves less necessary to the landholders, and furnishing the freedmen with opportunities of becoming farmers. on departing for europe he had parcelled out and let a part of the lands of cura, which extend towards the west at the foot of the rock of las viruelas. four years after, at his return to america, he found on this spot, finely cultivated in cotton, a little hamlet of thirty or forty houses, which is called punta zamuro, and which we visited with him. the inhabitants of this hamlet are almost all mulattos, zamboes, or free blacks. this example of letting out land has been happily followed by several other great proprietors. the rent is ten piastres for a fanega of ground, and is paid in money or in cotton. as the small farmers are often in want, they sell their cotton at a very moderate price. they dispose of it even before the harvest: and the advances, made by rich neighbours, place the debtor in a situation of dependence, which frequently obliges him to offer his services as a labourer. the price of labour is cheaper here than in france. a freeman, working as a day-labourer (peon), is paid in the valleys of aragua and in the llanos four or five piastres per month, not including food, which is very cheap on account of the abundance of meat and vegetables. i love to dwell on these details of colonial industry, because they serve to prove to the inhabitants of europe, a fact which to the enlightened inhabitants of the colonies has long ceased to be doubtful, namely, that the continent of spanish america can produce sugar, cotton, and indigo by free hands, and that the unhappy slaves are capable of becoming peasants, farmers, and landholders. end of volume . [illustration: pike's peak, colorado] earth and sky every child should know easy studies of the earth and the stars for any time and place by julia ellen rogers author of "the tree book," "the shell book," "key to the nature library," "trees every child should know." illustrated by thirty-one pages of photographs and drawings [illustration] new york grosset & dunlap publishers copyright, , by doubleday, page & company published, october, all rights reserved, including that of translation into foreign languages, including the scandinavian acknowledgments a number of the photographs in this volume are used by permission of the american museum of natural history. the star maps and drawings of the constellations are by mrs. jerome b. thomas. the poem by longfellow, quoted in part, is with the permission of the publishers, houghton, mifflin & co. * * * * * contents _part i. the earth_ page the great stone book the fossil fish the crust of the earth what is the earth made of? the first dry land a study of granite metamorphic rocks the air in motion the work of the wind rain in summer, _by henry w. longfellow_ what becomes of the rain? the soil in fields and gardens the work of earthworms quiet forces that destroy rocks how rocks are made getting acquainted with a river the ways of rivers the story of a pond the riddle of the lost rocks the question answered glaciers among the alps the great ice sheet following some lost rivers the mammoth cave of kentucky land building by rivers the making of mountains the lava flood of the northwest the first living things an ancient beach at ebb tide the lime rocks the age of fishes king coal how coal was made the most useful metal the age of reptiles the age of mammals the horse and his ancestors the age of man _part ii. the sky_ every family a "star club" the dippers and the pole star constellations you can always see winter constellations orion, his dogs, and the bull seven famous constellations the twenty brightest stars how to learn more illustrations pike's peak _frontispiece_ facing page sand dunes in arizona grand cañon of the colorado castles carved by rain and wind where all the water comes from the richest gold and silver mines rocks being ground to flour a pond made by a glacier the struggle between a stream and its banks ripple marks and glacial striæ glacial grooves and markings crinoid and ammonite fossil corals, coquina, hippurite limestone fossil fish meteorite eocene fish and trilobite how coal was made banded sandstone. opalized wood allosaurus a three-horned dinosaur remains of brontosaurus restoration of brontosaurus ornitholestes, a small dinosaur a mammoth an ancestor of the horse orion, his dogs, and the bull other fanciful sketches of constellations the sky in winter the sky in spring the sky in summer the sky in autumn part i the earth * * * * * the great stone book "the crust of our earth is a great cemetery where the rocks are tombstones on which the buried dead have written their own epitaphs. they tell us who they were, and when and where they lived."--_louis agassiz._ deep in the ground, and high and dry on the sides of mountains, belts of limestone and sandstone and slate lie on the ancient granite ribs of the earth. they are the deposits of sand and mud that formed the shores of ancient seas. the limestone is formed of the decayed shells of animal forms that flourished in shallow bays along those shores. and all we know about the life of these early days is read in the epitaphs written on these stone tables. under the stratified rocks, the granite foundations tell nothing of life on the earth. but the sea rolled over them, and in it lived a great variety of shellfish. evidently the earliest fossil-bearing rocks were worn away, for the rocks that now lie on the granite show not the beginnings, but the high tide of life. the "lost interval" of which geologists speak was a time when living forms were few in the sea. in the muddy bottoms of shallow, quiet bays lie the shells and skeletons of the creatures that live their lives in those waters and die when they grow old and feeble. we have seen the fiddler crabs by thousands on such shores, young and old, lusty and feeble. we have seen the rocks along another coast almost covered by the coiled shells of little gray periwinkles, and big clumps of black mussels hanging on the piers and wharfs. all these creatures die, at length, and their shells accumulate on the shallow sea bottom. who has not spent hours gathering dead shells which the tide has thrown up on the beach? who has not cut his foot on the broken shells that lie in the sandy bottom we walk on whenever we go into the surf to swim or bathe? read downward from the surface toward the earth's centre-- table of contents ------+----------------------+-----------+----------------------- part | _rock systems_ | _dominant | _dominant plants_ | | animals_ | ------+----------------------+-----------+----------------------- vii. | recent | man | flowering kinds |{ quaternary | | vi. | { pliocene | mammals | early flowering |{ tertiary { miocene | | | { eocene | | v. | mesozoic | reptiles | cycads iv. | carboniferous | amphibians| ferns and conifers iii. | devonian | fishes | ferns ii. | silurian | molluscs | seaweeds i. | fire-formed | no life | no life ------+----------------------+-----------+----------------------- it is by dying that the creatures of the sea write their epitaphs. the mud or sand swallows them up. in time these submerged banks may be left dry, and become beds of stone. then some of the skeletons and shells may be revealed in blocks of quarried stone, still perfect in form after lying buried for thousands of years. the leaves of this great stone book are the layers of rock, laid down under water. between the leaves are pressed specimens--fossils of animals and plants that have lived on the earth. the fossil fish i remember seeing a flat piece of stone on a library table, with the skeleton of a fish distinctly raised on one surface. the friend who owned this strange-looking specimen told me that she found it in a stone quarry. she brought home a large piece of the slate, and a stone-mason cut out the block with the fish in it, and her souvenir made a useful and interesting paper-weight. the story of that fish i heard with wonder, and have never forgotten. i had never heard of fossil animals or plants until my good neighbour talked about them. she showed me bits of stone with fern leaves pressed into them. one piece of hard limestone was as full of little sea-shells as it could possibly be. one ball of marble was a honeycombed pattern, and called "fossil coral." the fossil fish was once alive, swimming in the sea, and feeding on the things it liked to eat, as all happy fishes do. near shore a river poured its muddy water into the sea, and the sandy bottom was covered with the mud that settled on it. at last the fish grew old, and perhaps a trifle stupid about catching minnows. it died, and sank to the muddy floor of the sea. its horny bones were not dissolved by the water. they remained, and the mud filtered in and filled all the spaces. soon the fish was buried completely by the sediment the river brought. years, thousands of them, went by, and the layer of mud was so thick and heavy above the skeleton of the fish that it bore a weight of tons there, under the water. the close-packed mud became a stiff clay. after more thousands of years, the sea no longer came so far ashore, for the river had built up a great delta of land out of mud. the clay in which the fish was hidden hardened into slate. water crept down in the loose upper layers, dissolving out salt and other minerals, and having harder work to soak through, the lower it went. the water left some of the minerals it had accumulated, calcium and silica and iron, in the lower rock beds, making them harder than they were before, and heavier and less porous. when the river gorge was cut through these layers of rock, the colour and thickness of each kind were laid bare. centuries after, perhaps thousands of years, indeed, the quarrymen cut out the layers fit for building stones, flags for walks and slates for roofing. in the splitting of a flagstone, the long-buried skeleton of the fish came to light. under our feet the earth lies in layers. under the soil lie loose beds of clay and sand and gravel, and under these loose kinds of earth are close-packed clays, sandstones, limestones, shales, often strangely tilted away from the horizontal line, but variously fitted, one layer to another. under these rocks lie the foundations of the earth--the fire-formed rocks, like granite. the depth of this original rock is unknown. it is the substance out of which the earth is made, we think. all the layered rocks are made of particles of the older ones, stolen by wind and water, and finally deposited on the borders of lakes and seas. so our rivers are doing to-day what they have always done--they are tearing down rocks, grinding and sifting the fragments, and letting them fall where the current of fresh water meets a great body of water that is still, or has currents contrary to that of the river. do you see a little dead fish in the water? it is on the way to become a fossil, and the mud that sifts over it, to become a layer of slate. every seashore buries its dead in layers of sand and mud. the crust of the earth it is hard to believe that our solid earth was once a ball of seething liquid, like the red-hot iron that is poured out of the big clay cups into the sand moulds at an iron foundry. but when a mountain like vesuvius sets up a mighty rumbling, and finally a mass of white-hot lava bursts from the centre and streams down the sides, covering the vineyards and olive orchards, and driving the people out of their homes in terror, it seems as if the earth's crust must be but a thin and frail affair, covering a fiery interior, which might at any time break out. the people who live near volcanoes might easily get this idea. but they do not. they go back as soon as the lava streams are cooled, and rebuild their homes, and plant more orchards and vineyards. "it is _so_ many years," say they to one another, "since the last bad eruption. vesuvius will probably sleep now till we are dead and gone." this is good reasoning. there are few active volcanoes left on the earth, compared with the number that were once active, and long ago became extinct. and the time between eruptions of the active ones grows longer; the eruptions less violent. terrible as were the recent earthquakes of san francisco and messina, this form of disturbance of the earth's crust is growing constantly less frequent. the earth is growing cooler as it grows older; the crust thickens and grows stronger as centuries pass. we have been studying the earth only a few hundred years. the crust has been cooling for millions of years, and mountain-making was the result of the shrinking of the crust. that formed folds and clefts, and let masses of the heated substance pour out on the surface. my first geography lesson i shall never forget. the new teacher had very bright eyes and _such_ pretty hands! she held up a red apple, and told us that the earth's substance was melted and burning, inside its crust, which was about as thick, in proportion to the size of the globe, as the skin of the apple. i was filled with wonder and fear. what if we children jumped the rope so hard as to break through the fragile shell, and drop out of sight in a sea of fiery metal, like melted iron? some of the boys didn't believe it, but they were impressed, nevertheless. the theory of the heated interior of the earth is still believed, but the idea that flames and bubbling metals are enclosed in the outer layer of solid matter has generally been abandoned. the power that draws all of its particles toward the earth's centre is stated by the laws of gravitation. the amount of "pull" is the measure of the weight of any substance. lift a stone, and then a feather pillow, much larger than the stone. one is strongly drawn to the earth; the other not. one is _heavy_, we say, the other _light_. if a stone you can pick up is heavy, how much heavier is a great boulder that it takes a four-horse team to haul. what tremendous weight there is in all the boulders scattered on a hillside! the hill itself could not be made level without digging away thousands of tons of earth. the earth's outer crust, with its miles in depth of mountains and level ground, is a crushing weight lying on the heated under-substance. every foot of depth adds greatly to the pressure exerted upon the mass, for the attraction of gravitation increases amazingly as the centre of the earth is approached. it is now believed that the earth is solid to its centre, though heated to a high degree. terrific pressure, which causes this heat, is exerted by the weight of the crust. a crack in the crust may relieve this pressure at some point, and a mass of substance may be forced out and burst into a flaming stream of lava. such an eruption is familiar in volcanic regions. the fact that red-hot lava streams from the crater of vesuvius is no proof that it was seething and bubbling while far below the surface. volcanoes, geysers, and hot springs prove that the earth's interior is hot. the crust is frozen the year around in the polar regions, and never between the tropics of cancer and capricorn. the sun's rays produce our different climates, but they affect only the surface. underground, there is a rise of a degree of temperature for every fifty feet one goes down. the lowest mine shaft is about a mile deep. that is only one four-thousandth of the distance to the earth's centre. by an easy computation we could locate the known melting-point for metals and other rock materials. but one degree for each fifty feet of depth below the surface may not be correct for the second mile, as it is for the first. again, the melting-point is probably a great deal higher for substances under great pressure. the weight of the crust is a burden the under-rocks bear. probably the pressure on every square inch reaches thousands of tons. could any substance become liquid with such a weight upon it, whatever heat it attained? nobody can answer this question. the theory that volcanoes are chimneys connecting lakes of burning lava with the surface of the earth is discredited by geologists. the weight of the overlying crust would, they think, close such chambers, and reduce liquids to a solid condition. since the first land rose above the sea, the crust of the earth has gradually become more stable, but even now there is scarcely a day when the instruments called seismographs do not record earthquake shocks in some part of the earth; and the outbreaks of vesuvius and Ætna, the constant boiling of lava in the craters of the hawaiian islands and other volcanic centres, prove that even now the earth's crust is very thin and unstable. the further back in time we go, the thinner was the crust, the more frequent the outbursts of volcanic activity, the more readily did wrinkles form. the shores of new jersey and of greenland are gradually sinking, and the sea coming up over the land. certain parts of the world are gradually rising out of the sea. in earlier times the rising or the sinking of land over large areas happened much more frequently than now. what is the earth made of? "baking day" is a great institution in the comfortable farm life of the american people. the big range oven is not allowed to grow cold until rows of pies adorn the pantry shelves, and cakes, tarts, and generous loaves of bread are added to the store. cookies, perhaps, and a big pan full of crisp, brown doughnuts often crown the day's work. no gallery of art treasures will ever charm the grown-up boys and girls as those pantry shelves charmed the bright-eyed, hungry children, who were allowed to survey the treasure-house, and sample its good things while they were still warm. you could count a dozen different kinds of cakes and pies, rolls and cookies on those pantry shelves, yet several of them were made out of the same dough. instead of a loaf of bread, mother could make two or three kinds of coffee cake, or cinnamon rolls, or currant buns, or parker-house rolls. even the pastry, which made the pies and tarts, was not so different from the bread dough, for each was made of flour, and contained, besides the salt, "shortening," which was butter or lard. sugar was used in everything, from the bread, which had a table-spoonful, to the cookies, which were finished with a sifting of sugar on top. how much of the food we eat is made of a very few staple foodstuffs,--starch, sugar, fats! so in the wonderful earth and all that grows out of it and lives upon it. only seventy different elements have been discovered, counting, besides the earth, the water and the air, and even the strange wandering bodies, called meteorites, that fall upon the earth out of the sky. like the flour in the different cakes and pies, the element carbon is found in abundance and in strangely different combinations. as a gas, in combination with oxygen, it is breathed out of our lungs, and out of chimneys where coal and wood are burned. it forms a large part of the framework of trees and other plants, and remains as charcoal when the wood is slowly burned under a close covering. there is a good proportion of carbon in animal bodies, in the bones as well as the soft parts, and carbon is plentiful in the mineral substances of the earth. the chemist is the man who has determined for us the existence and the distribution of the seventy elements. he finds them in the solid substances of the globe and in the water that covers four-fifths of its surface; in the atmosphere that covers sea and land, and in all the living forms of plants and animals that live in the seas and on the land. by means of an instrument called the spectroscope, the heavenly bodies are proved to be made of the same substances that are found in the rocks. the sun tells what it is made of, and one proof that the earth is a child of the sun is in the fact that the same elements are found in the substance of both. of the seventy elements, the most important are these: oxygen, silicon, aluminum, iron, manganese, calcium, magnesium, potassium, sodium, carbon, hydrogen, phosphorus, sulphur, chlorine, nitrogen. _oxygen_ is the most plentiful and the most important element. one-fifth of the air we breathe is oxygen; one-third of the water we drink. the rock foundations of the earth are nearly one-half oxygen. no fire can burn, no plant or animal can grow, or even decay after it dies, unless oxygen is present and takes an active part in each process. strangely enough, this wonderful element is invisible. we open a window, and pure air, rich in oxygen, comes in and takes the place of the bad air but we cannot see the change. water we see, but if the oxygen and the hydrogen which compose the colourless liquid were separated, each would become at once an invisible gas. the oxygen of solid rocks exists only in combination with other elements. _silicon_ is the element which, united with oxygen, makes the rock called quartz. on the seashore the children are busy with their pails and shovels digging in the white, clean sand. these grains are of quartz,--fine crystals of a rock which forms nearly three-quarters of the solid earth's substance. not only in rocks, but out here in the garden, the soil is full of particles of sand. you cannot get away from it. _aluminum_ is a light, bluish-white metal which we know best in expensive cooking utensils. it is more abundant even than iron, but processes of extracting it from the clay are still expensive. it is oftenest found in combination with oxygen and silicon. while nearly one-tenth of the earth's crust is composed of the metal aluminum, four-fifths and more is composed of the minerals called silicates of aluminum--oxygen, silicon, and aluminum in various combinations. it is more plentiful than any other substance in rocks and in the clays and ordinary soils, which are the finely ground particles of rock material. _iron_ is one of the commonest of elements. we know it by its red colour. a rusty nail is covered with oxide of iron, a combination which is readily formed wherever iron is exposed to the action of water or air. you have seen yellowish or red streaks in clefts of the rocks. this shows where water has dissolved out the iron and formed the oxide. the red colour of new jersey soil is due to the iron it contains. indeed, the whole earth's crust is rich in iron which the water easily dissolves. the roots of plants take up quantities of iron in solution and this mounts to the blossoms, leaves, and fruit. the red or yellow colour of autumn leaves, of apples, of strawberries, of tulips, and of roses, is produced by iron. the rosy cheeks of children are due to iron in the food they eat and in the water they drink. the doctor but follows the suggestion of nature when he gives a pale and listless person a tonic of iron to make his blood red. iron is rarely found free, but it forms about five per cent. of the crust of the earth, and it is believed to form at least one-fifth of the unknown centre of the earth, the bulk of the globe, the weight of which we know, but concerning the substance of which we can say little that is positive. _manganese_ is not a conspicuous element, but is found united with oxygen in purplish or black streaks on the sides of rocks. it is somewhat like iron, but much less common. _calcium_ is the element that is the foundation of limestones. the skeletons and shells of animals are made of calcite, a common mineral formed by the uniting of carbon, oxygen, and calcium. marbles are, perhaps, the most permanent form of the limestone rocks. "hard" water has filtered through rocks containing calcite, and absorbed particles of this mineral. from water thus impregnated, all animal life on the earth obtains its bone-building and shell-building materials. _carbon_ forms a large part of the tissues of plants and animals, and in the remains of these it is chiefly found in the earth's crust. when these burn or decay, the carbon remains as charcoal or escapes to the air in union with oxygen as the well known carbonic acid gas. this is one of the most important foods of plants. joined with calcium it forms the mineral calcite, or carbonate of lime. _hydrogen_ is one of the two gases that unite to form water. oxygen is the other. many kinds of rock contain a considerable amount of water. surface water sinks into porous soils and rocks, and accumulates in pockets and veins which feed springs, and are the reserve water supply that keeps our rivers flowing, even through dry weather. more water is held by absorption in the earth's solid crust than in all the oceans and seas and great lakes. hydrogen, combined with carbon, occurs in solid rocks where the remains of plants and animals have slowly decayed. from such processes the so-called hydrocarbons, rock oil and natural gas, have accumulated. when such decay goes on above ground, these valuable products escape into the air. marsh gas, whose feeble flame above decaying vegetation is the will-o'-the-wisp of swamps, is an example. _magnesium_, _potassium_, and _sodium_ are found in equal quantities in the earth's crust, but never free. in union with chlorine, each forms a soluble salt, and is thus found in water. common salt, chloride of sodium, is the most abundant of these. water dissolves salt out of the rocks, and carries it into the sea. clouds that rise by the evaporation of ocean water leave the salt behind, hence the seas are becoming more and more salty, for the rivers carry salt to the oceans, which hold fast all they get. _phosphorus_ is an element found united with oxygen in the tissues of both plants and animals. it is most abundant in bones. rocks containing fossil bones are rich in lime phosphates, which are important commercial fertilizers for enriching the soil. beds of these rocks are found and mined in south carolina and elsewhere. _sulphur_ is well known as a yellow powder found most plentifully in rocks that are near volcanoes. it is a needed element in plant and animal bodies. it occurs in rocks, united with many different elements. in union with oxygen and a metal it forms the group of minerals called sulphates. in union with iron it forms sulphide of iron. the "fool's gold" which captain john smith's colonists found in the sand at jamestown, was this worthless iron pyrites. _chlorine_ is a greenish, yellow gas, very heavy, and dangerous to inhale. if it gets into the lungs, it settles into the lowest levels, and one must stand on one's head to get it out. as an element of the earth's crust it is not very plentiful, but it is a part of all the chlorides of sodium, magnesium, and potassium. in salt, it forms two per cent. of the sea water. it is much less abundant in the rocks. to these elements we might add _nitrogen_, that invisible gas which forms nearly four-fifths of our atmosphere, and is a most important element of plant food in the soil. most of the seventy elements are very rare. many are metals, like gold and iron and silver. some are not metals. some are solid. a few are liquid, like the metal mercury, and several are gaseous. some are free and pure, and show no disposition to unite with others. nuggets of gold are examples of this. some exist only in union with other elements. this is the common rule among the elements. changes are constantly going on. the elements are constantly abandoning old partnerships and forming new ones. growth and decay of plant and animal life are but parts of the great programme of constant change which is going on and has been in progress since the world began. the first dry land when the earth's crust first formed it was still hot, though not so hot as when it was a mass of melted, glowing substance. as it moved through the cold spaces of the sky, it lost more heat and its crust became thicker. at length the cloud masses became condensed enough to fall in torrents of water, and a great sea covered all the land. this was before any living thing, plant or animal, existed on our planet. can you imagine the continents and islands that form the land part of a map or globe suddenly overwhelmed by the oceans, the names and boundaries of which you have taken such pains to learn in the study of geography? the globe would be one blank of blue water, and geography would be abolished--and there would be nobody to study it. possibly the fishes in the sea might not notice any change in the course of their lives, except when they swam among the ruins of buried cities and peered into the windows of high buildings, or wondered what new kind of seaweed it was when they came upon a submerged forest. in that old time of the great sea that covered the globe, we are told that there was a dense atmosphere over the face of the deep. so things were shaping themselves for the far-off time when life should exist, not only in the sea, where the first life did appear, but on land. but it took millions of years to fit the earth for living things. the cooling of the earth made it shrink, and the crust began to be folded into gentle curves, as the skin of a shrunken apple becomes wrinkled on the flesh. some of these creases merely changed the depth of water on the sea bottom; but one ridge was lifted above the water. the water parted and streamed down its sloping sides, and a granite reef, which shone in the sunshine, became the first dry land. it lay east and west, and stretched for many miles. it is still dry land and is a part of our own continent. now it is but a small part of the country, but it is known by geologists, who can tell its boundaries, though newer land joins it on every side. it is named the laurentian hills, on geological maps. its southern border reaches along the northern boundary of the great lakes to the head-waters of the mississippi river. from this base, two ridges are lifted, forming a colossal v. one extends northeast to nova scotia; the other northwest to the arctic seas. the v encloses hudson bay. besides this first elongated island of bare rocks, land appeared in a strip where now the blue ridge mountains stretch from new england to georgia. the other side of the continent lifted up two folds of the crust above sea level. they are the main ridges of the colorado and the wasatch mountains. possibly the main ridge of the sierra nevada rose also at this time. the ozark group of mountains, too, showed as a few island peaks above the sea. these first rocks were rapidly eaten away, for the atmosphere was not like ours, but heavily charged with destructive gases, which did more, we believe, to disintegrate the exposed rock surfaces than did the two other forces, wind and water, combined. the sediment washed down to the sea by rains, accumulated along the shores, filling the shallows and thus adding to the width of the land areas. the ancient granite ridge of the laurentian hills is now low, and slopes gently. this is true of all very old mountains. the newer ones are high and steep. it takes time to grind down the peaks and carry off the waste material loosened by erosion. far more material than could have been washed down the slopes of the first land ridges came directly from the interior of the earth, and spread out in vast, submarine layers upon the early crust. volcanic craters opened under water, and poured out liquid mineral matter, that flowed over the sea bottom before it cooled. imagine the commotion that agitated the water as these submerged chimneys blew off their lids, and discharged their fiery contents! it was long before the sea was cool enough to be the home of living things. the layers of rock that formed under the sea during this period of the earth's history are of enormous thickness. they were four or five miles deep along the laurentian hills. they broadened the original granite ridge by filling the sea bottom along the shores. the backbones of the appalachian system and the cordilleras were built up in the same way--the oldest rocks were worn away, and their débris built up newer ones in strata. when these layers of rock became dry land, the earth's crust was much more stable and cool than it had ever been before. the vast rock-building of that era equals all that has been done since. the layers of rocks formed since then do not equal the total thickness of these first strata. so we believe that the time required to build those archæan rock foundations equals or surpasses the vast period that has elapsed since the archæan strata were formed. the northern part of north america has grown around those old granite ridges by the gradual rising of the shores. the geologist may walk along the laurentian hills, that parted the waters into a northern and a southern ocean. he crosses the rocky beds deposited upon the granite; then the successive beds formed as the land rose and the ocean receded. age after age is recorded in the rocks. gradually the sea is crowded back, and the land masses, east, west, and north, meet to form the continent. nowhere on the earth are the steps of continental growth shown in unbroken sequence as they are in north america. how long ago did those first islands appear above the sea? nobody ventures a definite answer to this question. no one has the means of knowing. but those who know most about it estimate that at the least one hundred million years have passed since then--one hundred thousand thousand years! a study of granite in every village cemetery it is easy to find shafts of gray or speckled granite, the polished surfaces of which show that the granite is made of small bits of different coloured minerals, cemented together into solid rock. outside the gate you will usually find a place where monuments and gravestones may be bought. here there is usually a stonecutter chipping away on a block with his graving tools. he is a man worth knowing, and because his work is rather monotonous he will probably be glad to talk to a chance visitor and answer questions about the different kinds of stone on which he works. there are bits of granite lying about on the ground. if you have a hand-glass of low power, such as the botany class uses to examine the parts of flowers, it will be interesting to look through it and see the magnified surface of a flake of broken granite. here are bits of glassy quartz, clear and sparkling in the sun. black and white may be all the colours you make out in this specimen, or it may be that you see specks of pink, dark green, gray, and smoky brown, all cemented together with no spaces that are not filled. the particles of quartz are of various colours, and are very hard. they scratch glass, and you cannot scratch them with the steel point of your knife, as you can scratch the other minerals associated with the grains of quartz. granite is made of quartz, feldspar, and mica, sometimes with added particles of hornblende. feldspar particles have as wide a range of colour as quartz, but it is easy to tell the two apart. a knife will scratch feldspar, as it is not so hard as quartz. the crystals of feldspar have smooth faces, while quartz breaks with a rough surface as glass does. feldspar loses its glassy lustre when exposed to the weather, and becomes dull, with the soft lustre of pearl. mica may be clear and glassy, and it ranges in colour from transparency through various shades of brown to black. it has the peculiarity of splitting into thin, leaf-like, flexible sheets, so it is easy to find out which particles in a piece of granite are mica. one has only to use one's pocket knife with a little care. hornblende is a dark mineral which contains considerable iron. it is found in lavas and granites, where it easily decays by the rusting of the iron. it is not unusual to see a rough granite boulder streaked with dark red rust from this cause. the crumbling of granite is constantly going on as a result of the exposure of its four mineral elements to the air. quartz is the most stable and resistant to weathering. soil water trickling over a granite cliff has little effect on the quartz particles; but it dissolves out some of the silicon. the bits of feldspar are even more resistant to water than quartz is, but the air causes them to decay rapidly, and finally to fall away in a sort of mealy clay. mica, like feldspar, decays easily. its substance is dissolved by water and carried away to become a kind of clay. the hornblende rusts away chiefly under the influence of moist air and trickling water. we think of granite as a firm, imperishable kind of rock, and use it in great buildings like churches and cathedrals that are to stand for centuries. but the faces that are exposed to the air suffer, especially in regions having a moist climate. the signs of decay are plainly visible on the outer surfaces of these stones. fortunate it is that the weathering process cannot go very deep. the glassy polish on a smooth granite shaft is the silicon which acts as a cement to bind all the particles together. it is resistant to the weather. a polished shaft will last longer than an unpolished one. granites differ in colouring because the minerals that compose them, the feldspars, quartzes, micas, and hornblendes, have each so wide a range of colour. again, the proportions of the different mineral elements vary greatly in different granites. a banded granite the colours of which give it a stratified appearance is called a gneiss. we have spoken before of the seventy elements found in the earth's crust. a mineral is a union of two or more of these different elements; and we have found four minerals composing our granite rock. it may be interesting to go back and inquire what elements compose these four minerals. quartz is made of silicon and oxygen. feldspar is made of silicon, oxygen, and aluminum. mica is made of silicon, oxygen, and carbon, with some mingling of potassium and iron and other elements in differing proportions. hornblende is made of silicon, oxygen, carbon, and iron. the crumbling of a granite rock separates the minerals that compose it, reducing some to the condition of clay, others to grains of sand. some of the elements let go their union and become free to form new unions. water and wind gather up the fragments of crumbling granite and carry them away. the feldspar and mica fragments form clay; the quartz fragments, sand. all of the sandstones and slates, the sand-banks and sand beaches, are made out of crumbled granite, the rocky foundations of the earth. metamorphic rocks in the dawn of life on the earth, soft-bodied creatures, lowest in the scale of being, inhabited the sea. the ancient volcanoes the subterranean eruptions of which had spread layers of mineral substance on the ocean floor, and heated the water to a high degree, had subsided. the ocean was sufficiently cool to maintain life. the land was being worn down, and its débris washed into the ocean. the first sand-banks were accumulating along sandy shores. the finer sediment was carried farther out and deposited as mud-banks. these were buried under later deposits, and finally, by the rising of the earth's crust, they became dry land. time and pressure converted the sand-banks into sandstones; the mud-banks into clay. the remains of living creatures utterly disappeared, for they had no hard parts to be preserved as fossils. the shrinking of the earth's crust had crumpled into folds of the utmost complexity those horizontal layers of lava rock poured out on the ocean floor. next, the same forces attacked the thick rock layers formed out of sediment--the aqueous or water-formed sandstones and clays. the core of the globe contracts, and the force that crumples the crust to fit the core generates heat. the alkaline water in the rocks joins with the heat produced by the crumpling and crushing forces, acting downward, and from the sides, to transform pure sandstone into glassy quartzite, and clay into slate. in other words, water-formed rocks are baked until they become fire-formed rocks. they are what the geologist calls _metamorphic_, which means _changed_. in many mountainous regions there are breaks through the strata of sandstone and slates and limestones, through which streams of lava have poured forth from the heated interior. along the sides of these fissures the hot lava has changed all the rocks it touched. the heat of the volcanic rock matter has melted the silica in the sand, which has hardened again into a crystalline substance like glass. have you ever visited a brick-yard? here men are sifting clay dug out of a pit or the side of a hill, adding sand from a sand-bank, and in a big mixing box, stirring these two "dry ingredients" with water into a thick paste. this dough is moulded into bricks, sun-dried, and then baked in kilns themselves built of bricks. at the end of the baking, the soft, doughy clay block is transformed into a hard, glassy, or dull brick. from aqueous rock materials, fire has produced a metamorphic rock. volcanic action is imitated in this common, simple process of brickmaking. milwaukee brick is made of clay that has no iron in it. for this reason the bricks are yellow after baking. most bricks are red, on account of the iron in the clay, which is converted into a red oxide, or rust, by water and heat. common flower pots and the tiles used in draining wet land are not glazed, as hard-burned bricks are. the baking of these clay things is done with much less heat. they are left somewhat porous. but the tiles of roofs are baked harder, and get a surface glaze by the melting of the glassy particles of the sand. as bricks vary in colour and quality according to the materials that compose them, so the metamorphic rocks differ. the white sand one sees on many beaches is largely quartz. this is the substance of pure, white sandstone. metamorphism melts the silica into a glassy liquid cement; the particles are bound close together on cooling. the rock becomes a white, granular quartzite, that looks like loaf sugar. if banded, it is called gneiss. such rocks take a fine polish. pure limestone is also white and granular. when metamorphosed by heat, it becomes white marble. the glassy cement that holds the particles of lime carbonate shows as the glaze of the polished surface. it is silica. one sees the same mineral on the face of polished granite. clays are rarely pure. kaolin is a white clay which, when baked, becomes porcelain. china-ware is artificially metamorphosed kaolin. in the early rocks the clay beds were transformed by heat into jasper and slates. in beds where clay mingled with sand, in layers, gneiss was formed. if mica is a prominent element, the metamorphic rock is easily parted into overlapping, scaly layers. it is a mica schist. if hornblende is the most abundant mineral, the same scaly structure shows in a dark rock called hornblende schist, rich in iron. a schist containing much magnesia is called serpentine. the bricks of the wall, the tiles on the roof, the flower pots on the window sill, and the dishes on the breakfast table, are examples of metamorphic rocks made by man's skill, by the use of fire and water acting on sand and clay. pottery has preserved the record of civilization, from the making of the first crude utensils by cave men to the finest expression of decorative art in glass and porcelain. the choicest material of the builder and the sculptor is limestone baked by the fires under the earth's crust into marble. the most enduring of all the rocks are the foundation granite, and the metamorphic rocks that lie next to them. over these lie thick layers of sedimentary rocks laid down by water. in them the record of life on the earth is written in fossils. the air in motion most of the beautiful things that surround us and make our lives full of happiness appeal to one or more of our five senses. the green trees we can see, the bird songs we hear, the perfume of honey-laden flowers we smell, the velvety smoothness of a peach we feel, and its rich pulp we taste. but over all and through all the things we see and feel and hear and taste and smell, is the life-giving air, that lies like a blanket, miles in depth, upon the earth. the substance which makes the life of plants and animals possible is, when motionless, an invisible, tasteless, odourless substance, which makes no sound and is not perceptible to the touch. air fills the porous substance of the earth's crust for a considerable distance, and even the water has so much air in it that fishes are able to breathe without coming to the surface. it is not a simple element, like gold, or carbon, or calcium, but is made up of several elements, chief among which are nitrogen and oxygen. four-fifths of its bulk is nitrogen and one-fifth oxygen. there is present in air more or less of watery vapour and of carbon dioxide, the gas which results from the burning or decay of any substance. although no more than one per cent. of the air that surrounds us is water, yet this is a most important element. it forms the clouds that bear water back from the ocean and scatter it in rain upon the thirsty land. solid matter in the form of dust, and soot from chimneys, accumulates in the clouds and does a good work in condensing the moisture and causing it to fall. it is believed that the air reaches to a height of one hundred to two hundred miles above the earth's surface. if a globe six feet in diameter were furnished with an atmosphere proportionately as deep as ours, it would be about an inch in depth. at the level of the sea the air reaches its greatest density. two miles above sea-level it is only two-thirds as dense. on the tops of high mountains, four or five miles above sea level, the air is so rarefied as to cause the blood to start from the nostrils and eyelids of explorers. the walls of the little blood-vessels are broken by the expansion of the air that is inside. at the sea-level air presses at the rate of fifteen pounds per square foot in all directions. as one ascends to higher levels, the air pressure becomes less and less. the barometer is the instrument by which the pressure of air is measured. a glass tube, closed at one end, and filled with mercury, the liquid metal often called quicksilver, is inverted in a cup of the same metal, and so supported that the metal is free to flow between the two vessels. the pressure of air on the surface of the mercury in the cup is sufficient at the sea-level to sustain a column of mercury thirty inches high in the tube. as the instrument is carried up the side of a mountain the mercury falls in the tube. this is because the air pressure decreases the higher up we go. if we should descend into the shaft of the deepest mine that reaches below the sea level, the column of air supported by the mercury in the cup would be a mile higher, and for this reason its weight would be correspondingly greater. the mercury would thus be forced higher in the tube than the thirty-inch mark, which indicates sea-level. another form of barometer often seen is a tube, the lower and open end of which forms a u-shaped curve. in this open end the downward pressure of the air rests upon the mercury and holds it up in the closed end, forcing it higher as the instrument is carried to loftier altitudes. at sea level a change of feet in altitude makes a change of an inch in the height of the mercury in the column. the glass tube is marked with the fractions of inches, or of the metre if the metric system of measurements is used. it is a peculiarity of air to become heated when it is compressed, and cooled when it is allowed to expand again. it is also true that when the sun rises, the atmosphere is warmed by its rays. this is why the hottest part of the day is near noon when the sun's rays fall vertically. the earth absorbs a great deal of the sun's heat in the daytime and through the summer season. when it cools this heat is given off, thus warming the surrounding atmosphere. in the polar regions, north and south, the air is far below freezing point the year round. in the region of the equator it rarely falls below degrees, a temperature which we find very uncomfortable, especially when there is a good deal of moisture in the air. if we climb a mountain in mexico, we leave the sultry valley, where the heat is almost unbearable, and very soon notice a change. for every three hundred feet of altitude we gain there is a fall of one degree in the temperature. before we are half way up the slope we have left behind the tropical vegetation, and come into a temperate zone, where the plants are entirely different from those in the lower valley. as we climb, the vegetation becomes stunted, and the thermometer drops still lower. at last we come to the region of perpetual snow, where the climate is like that of the frozen north. so we see that the air becomes gradually colder as we go north or south from the equator, and the same change is met as we rise higher and higher from the level of the sea. it is only when air is in motion that we can feel and hear it, and there are very few moments of the day, and days of the year, when there is not a breeze. on a still day fanning sets the air in motion, and creates a miniature breeze, the sound of which we hear in the swishing of the fan. the great blanket of air that covers the earth is in a state of almost constant disturbance, because of the lightness of warm air and the heaviness of cold air. these two different bodies are constantly changing places. for instance, the heated air at the equator is constantly being crowded upward by cold air which settles to the level of the earth. cold streams of air flow to the tropics from north and south of the equator, and push upward the air heated by the sun. this constant inrush of air from north and south forms a double belt of constant winds. if the earth stood still, no doubt the direction would be due north and due south for these winds; but the earth rotates rapidly from west to east upon its axis, carrying with it everything that is securely fastened to the surface: the trees, the houses, etc. but the air is not a part of the earth, not even so much as the seas, the waters of which must stay in their proper basins, and be whirled around with other fixed objects. the earth whirls so rapidly that the winds from north and south of the equator lag behind, and thus take a constantly diagonal direction. instead of due south the northern belt of cold air drifts south-west and the southern belt drifts northwest. these are called the trade winds. near the equator they are practically east winds. the belt of trade winds is about fifty degrees wide. it swings northward in our summer and southward in our winter, its centre following the vertical position of the sun. near the centre of the course which marks the meeting of the northern with the southern winds is a "belt of calms" where the air draws upward in a strong draught. the colder air of the trade winds is pushing up the columns of light, heated air. this strip is known by sailors as "the doldrums," or "the region of equatorial calms." though never wider than two or three hundred miles, this is a region dreaded by captains of sailing-vessels, for they often lie becalmed for weeks in an effort to reach the friendly trade winds that help them to their desired ports. vessels becalmed are at the mercy of sudden tempests which come suddenly like thunder-storms, and sometimes do great damage to vessels because they take the sailors unawares and allow no time to shorten sail. until late years the routes of vessels were charted so that sailors could take advantage of the trade winds in their long voyages. it was necessary in the days of sailing-vessels for the captain to understand the movements of winds which furnished the motive power that carried his vessel. fortunate it was for him that there were steady winds in the temperate zones that he could take advantage of in latitudes north of the tropic of cancer and south of the tropic of capricorn. what becomes of the hot air that rises in a constant stream above the "doldrums," pushed up by the cooler trade winds that blow in from north and south? naturally this air cannot ascend very high, for it soon reaches an altitude in which its heat is rapidly lost, and it would sink if it were not constantly being pushed by the rising column of warm air under it. so it turns and flows north and south at a level above the trade winds. not far north of the tropic of cancer it sinks to the level of sea and land, and forms a belt of winds that blows ships in a northeasterly direction. between trades and anti-trades is another zone of calms,--near the tropics of cancer and of capricorn. the land masses of the continents with their high mountain ranges interfere with these winds, especially in the northern hemisphere, but in the southern pacific and on the opposite side of the globe the "roaring forties," as these prevailing westerly winds are known by the sailors, have an almost unbroken waste of seas over which they blow. in the long voyages between england and australia, and in the indian trade, the ships of england set their sails to catch the roaring forties both going and coming. they accomplish this by sailing past the cape of good hope on the outward voyage and coming home by way of cape horn, thus circling the globe with every trip. in the north atlantic, traffic is now mostly carried on in vessels driven by engines, not by sails. yet the westerly winds that blow from the west indies diagonally across the atlantic are still useful to all sailing craft that are making for british ports. from the north and from the south cold air flows down into the regions of warmer climate. these polar winds are not so important to sea commerce, but they do a great work in tempering the heat in the equatorial regions. we cannot know how much our summers are tempered by the cool breath of winds that blow over polar ice-fields. and the cold regions of the earth, in their brief summer, enjoy the benefits of the warm breezes that flow north and south from the heated equatorial regions. the land, north and south, is made habitable by the clouds. they gather their burdens of vapour from the warm seas, the wind drifts them north and south, where they let it fall in rains that make and keep the earth green and beautiful. from the clouds the earth gathers, like a great sponge, the water that stores the springs and feeds rivers and lakes. how necessary are the winds that transport the cloud masses! the air is the breath of life to all living things on our planet. mars is one of the sun's family so provided. plants or animals could probably live on the planet mars. do we think often enough of this invisible, life-giving element upon which we depend so constantly? the open air which the wind purifies by keeping it in motion is the best place in which to work, to play, and to sleep, when work and play are done and we rest until another day comes. indoors we need all the air we can coax to come in through windows and doors. fresh air purifies air that is stale and unwholesome from being shut up. nobody is afraid, nowadays, to breathe night air! what a foolish notion it was that led people to close their bedroom windows at night. clean air, in plenty, day and night, we need. air and sunshine are the two best gifts of god. the work of the wind when the march wind comes blustering down the street, rudely dashing a cloud of dust in our faces, we are uncomfortable and out of patience. we duck our heads and cover our faces, but even then we are likely to get a cinder in one eye, to swallow germs by the dozens, and to get a gray coating of plain, harmless dust. we welcome the rain that lays the dust, or its feeble imitation, the water sprinkler, that brings us temporary relief. on the quietest day, even after a thorough sweeping and dusting of the library, you are able to write your name plainly on the film of dust that lies on the polished table. take a book from the open shelves, and blow into the trough of its top. this is always dusty. where does the dust come from? this is the house-keeper's riddle. the answer is not a hard one. i look out of my window on a street which is famous as the road washington took on his retreat from white plains to trenton. it has always been the main thoroughfare between new york and philadelphia, and now is the route that automobiles follow. a constant procession of vehicles passes my house, and to-day each one approaches in a cloud of dust. the air is gray with suspended particles of dirt. the wind carries the successive clouds, and they roll up against the houses like breakers on the beach. windows and doors are loose enough to let dust sift in. when a door opens, the cloud enters and lights on rugs and carpets and curtains. any ledge collects its share of dust. the beating of carpets and rugs disturbs the accumulated dust of many months. [illustration: in this lonely arizona desert the wind drifts the sand into dunes, just as it does on the toe of cape cod] [illustration: the grand canyon of the colorado shows on a magnificent scale the work of water in cutting away rock walls] the wind sweeps the ploughed field, and takes all the dust it can carry. it blows the finest top soil from our gardens into the street. it blows soil from other fields and gardens into ours, so the level of our land is not noticeably lowered. the wind strips the high land and drops its burden on lower levels. this is one of the big jobs the water has to do, and the wind is a valuable helper. to tear down the mountains and fill in the valleys is the great work of the two partners, wind and water. dead, still air holds the finest dust, without letting it fall. the buoyancy of the particles overcomes their weight. we see them in a sunbeam, like shining points of precious metal, and watch them. a light breeze picks up bits of soil and litter, from the smallest up to a certain size and weight. if the velocity of the wind increases, its carrying power increases. it is able to carry bits that are larger and heavier. the following table is exact and interesting: _velocity_ _pressure_ _in miles_ _in pounds_ _per hour_ _per sq. ft._ light breeze strong breeze strong gale hurricane the terrible paths of hurricanes are seen in forest countries. the trees are uprooted, as if a great roller had crushed them, throwing the tops all in one direction, and leaving the roots uncovered, and a sunken pocket where each tree stood. on a steep, rocky slope, the uprooting of scattered trees often loosens tons of rock, and sends the mass thundering down the mountain-side. much more destruction may be accomplished by one brief tornado than by years of wear by ordinary breezes. the wind does much to help the waves in their patient beating on rocky shores. if the wind blows from the ocean and the tide is landward, the two forces combine, and the loose rocks are thrown against the solid beach with astonishing force. even the gravel and the sharp sand are tools of great usefulness to the waves in grinding down the resisting shore. up and back they are swept by the water, and going and coming they have their chance to scratch or strike a blow. boulders on the beach become pockmarked by the constant sand-blast that plays upon them. the lower windows of exposed seaside houses are dimmed by the sand that picks away the smooth surface outside, making it ground glass by the same process used in the factory. lighthouses have this difficulty in keeping their windows clear. the "lantern" itself is sometimes reached by the sand grains. that is the cupola in which burns the great light that warns vessels away from the rocks and tells the captain where he is. in the far western states the telegraph poles and fence posts are soon cut off at the ground by the flinty knives the wind carries. these are the grains of sand that are blown along just above the ground. the trees are killed by having their bark girdled in this way. the sand-storms which in the orange and lemon region of california are called "santa anas" sometimes last two or three days, and damage the trees by piercing the tender bark with the needle-pointed sand. wind-driven soil, gathered from the sides of bare hills and mountains, fills many valleys of china with a fine, hard-packed material called "loess." in some places it is hundreds of feet deep. the people dig into the side of a hill of this loess and carry out the diggings, making themselves homes, of many rooms, with windows, doors, and solid walls and floors, all in one solid piece, like the chambered house a mole makes underground in the middle of a field. so compact is the loess that there is no danger of a cave-in. the hills of sand piled up on the southern shore of lake michigan, and at provincetown, at the toe of cape cod, are the work of the wind. on almost any sandy shore these "dunes" are common. the long slope is toward the beach that furnishes the sand. the wind does the building. up the slope it climbs, then drops its burden, which slides to the bottom of an abrupt landward steep. there is a gradual movement inland if the strongest winds come from the water. the shifting of the dunes threatens to cover fertile land near them. in the desert regions, the border-land is always in danger of being taken back again, even though it has been reclaimed from the desert and cultivated for long years. besides tearing down, carrying away, and building up again the fragments of the earth's crust, the wind does much that makes the earth a pleasant planet to live on. it drives the clouds over the land, bringing rains and snows and scattering them where they will bless the thirsty ground and feed the springs and brooks and rivers. it scatters the seeds of plants, and thus plants forests and prairies and lovely mountain slopes, making the wonderful wild gardens that men find when they first enter and explore a new region. the trade winds blow the warm air of the tropics north and south, making the climate of the northern countries milder than it would otherwise be. sea winds blow coolness over the land in summer, and cool lake breezes temper the inland regions. from the snow-capped mountains come the winds that refresh the hot, tired worker in the valleys. everywhere the wind blows, the life-giving oxygen is carried. this is what we mean when we speak of fresh air. stagnant air is as unwholesome as stagnant water. constant moving purifies both. so we must give the wind credit for some of the greatest blessings that come into our lives. light and warmth come from the sun. pure water and pure air are gifts the bountiful earth provides. without them there would be no life on the earth. rain in summer how beautiful is the rain! after the dust and heat, in the broad and fiery street, in the narrow lane, how beautiful is the rain! how it clatters along roofs, like the tramp of hoofs! how it gushes and struggles out from the throat of the overflowing spout! across the window-pane it pours and pours; and swift and wide, with a muddy tide, like a river down the gutter roars the rain, the welcome rain! the sick man from his chamber looks at the twisted brooks; he can feel the cool breath of each little pool; his fevered brain grows calm again, and he breathes a blessing on the rain. --henry w. longfellow. what becomes of the rain? the clouds that sail overhead are made of watery vapour. sometimes they look like great masses of cotton-wool against the intense blue of the sky. sometimes they are set like fleecy plumes high above the earth. sometimes they hang like a sullen blanket of gray smoke, so low they almost touch the roofs of the houses. indeed, they often rest on the ground and then we walk through a dense fog. in their various forms, clouds are like wet sponges, and when they are wrung dry they disappear--all their moisture falls upon the earth. when the air is warm, the water comes in the form of rain. if it is cold, the drops are frozen into hail, sleet, or snow. all of the water in the oceans, in the lakes and rivers, great and small, all over the earth, comes from one source, the clouds. in the course of a year enough rain and snow fall to cover the entire surface of the globe to a depth of forty inches. this quantity of water amounts to , barrels on every acre. what becomes of it all? we can easily understand that all the seas and the other bodies of water would simply add forty inches to their depth, and many would become larger, because the water would creep up on their gradually sloping shores. we have to account for the rain and the snow that fall upon the dry land and disappear. go out after a drenching rainstorm and look for the answer to this question. the gullies along the street are full of muddy, running water. there are pools of standing water on level places, but on every slope the water is hurrying away. the ground is so sticky that wagons on country roads may mire to the hubs in the pasty earth. there is no use in trying to work in the garden or to mow the lawn. the sod is soft as a cushion, and the garden soil is water-soaked below the depth of a spading-fork. the sun comes out, warm and bright, and the flagstones of the sidewalk soon begin to steam like the wooden planks of the board walk. the sun is changing the surface water into steam which rises into the sky to form a part of another bank of clouds. the earth has soaked up quantities of the water that fell. if we followed the racing currents in the gullies we should find them pouring into sewer mains at various points, and from these underground pipes the water is conducted to some outlet like a river. all of the streams are swollen by the hundreds of brooks and rivulets that are carrying the surface water to the lowest level. [illustration: rain and wind are the sculptors that have carved these strange castles out of a rocky table] [illustration: all the water in the seas, lakes, rivers, and springs came out of the clouds] so we can see some of the rainfall going back to the sky, some running off through rivulets to the sea, and some soaking into the ground. it will be interesting to follow this last portion as it gradually settles into the earth. the soil will hold a certain quantity, for it is made up of fine particles, all separated by air spaces, and it acts like a sponge. in seasons of drought and great heat the sun will draw this soil water back to the surface, by forming cracks in the earth, and fine, hair-like tubes, through which the vapour may easily rise. the gardener has to rake the surface of the beds frequently to stop up these channels by which the sun is stealing the precious moisture. the water that the surface soil cannot absorb sinks lower and lower into the ground. it finds no trouble to settle through layers of sand, for the particles do not fit closely together. it may come to a bed of clay which is far closer. here progress is retarded. the water may accumulate, but finally it will get through, if the clay is not too closely packed. again it may sink rapidly through thick beds of gravel or sand. reaching another bed of clay which is stiffer by reason of the weight of the earth above it, the water may find that it cannot soak through. the only way to pass this clay barrier is to fill the basin, and to trickle over the edge, unless a place is found in the bottom where some looser substance offers a passage. let us suppose that a concave clay basin of considerable depth is filled with water-soaked sand. at the very lowest point on the edge of this basin a stream will slowly trickle out, and will continue to flow, as long as water from above keeps the bowl full. it is not uncommon to find on hillsides, in many regions, little brooks whose beginnings are traceable to springs that gush out of the ground. the spring fills a little basin, the overflow of which is the brook. if the source of this spring could be traced underground, we might easily follow it along some loose rock formation until we come to a clay basin like the one described above. we might have to go down quite a distance and then up again to reach the level of this supply, but the level of the water at the mouth of the spring can never be higher than the level of the water in the underground supply basin. often in hot summers springs "go dry." the level of water in the supply basin has fallen below the level of the spring. we must wait until rainfall has added to the depth of water in the basin before we can expect any flow into the pool which marks the place where the brook begins. suppose we had no beds of clay, but only sand and gravel under the surface soil. we should then expect the water to sink through this loose material without hindrance, and, finding its way out of the ground, to flow directly into the various branches of the main river system of our region. after a long rain we should have the streams flooded for a few days, then dry weather and the streams all low, many of them entirely dry until the next rainstorm. instead of this, the soil to a great depth is stored with water which cannot get away, except by the slow process by which the springs draw it off. this explains the steady flow of rivers. what should we do for wells if it were not for the water basins that lie below the surface? a shallow well may go dry. its owner digs deeper, and strikes a lower "vein" of water that gives a more generous supply. in the regions of the country where the drift soil, left by the great ice-sheet, lies deepest, the glacial boulder clay is very far down. the surface water, settling from one level to another, finally reaches the bottom of the drift. wells have to be deep that reach this water bed. the water follows the slope of this bed and is drained into the ocean, sometimes by subterranean channels, because the bed of the nearest river is on a much higher level. so we must not think that the springs contain only the water that feeds the rivers. they contain more. the layers of clay at different levels, from the surface down to the bottom of the drift, form water basins and make it possible for people to obtain a water supply without the expense of digging deep wells. the clayey subsoil, only a few feet below the surface, checks the downward course of the water, so that the sun can gradually draw it back, and keep a supply where plant roots can get it. the vapour rising keeps the air humid, and furnishes the dew that keeps all plant life comfortable and happy even through the hot summer months. under the drift lie layers of stratified rock, and under these are the granites and other fire-formed rocks, the beginning of those rock masses which form the solid bulk of the globe. we know little about the core of the earth, but the granites that are exposed in mountain ridges are found to have a great capacity for absorbing water, so it is not unlikely that much surface water soaks into the rock foundations and is never drained away into the sea. the water in our wells is often hard. it becomes so by passing through strata of soil and rock made, in part, at least, of limestone, which is readily dissolved by water which contains some acid. soil water absorbs acids from the decaying vegetation,--the dead leaves and roots of plants. rain water is soft, and so is the water in ponds that have muddy basins, destitute of lime. water in the springs and wells of the mid-western states is "hard" because it percolates through limestone material. in many parts of this country the well water is "soft," because of the scarcity of limestone in the soil. i have seen springs around which the plants and the pebbles were coated with an incrustation of lime. "petrified moss" is the name given to the plants thus turned to stone. the reason for this deposit is clear. underground water is often subjected to great pressure, and at this time it is able to dissolve much more of any mineral substance than under ordinary conditions. when the pressure is released, the water is unable to hold in solution the quantity of mineral it contains; therefore, as it flows out through the mouth of the spring, the burden of mineral is laid down. the plants coated with the lime gradually decay, but their forms are preserved. there are springs the water of which comes out burdened with iron, which is deposited as a yellowish or red mineral on objects over which it flows. ponds fed by these springs accumulate deposits of the mineral in the muddy bottoms. some of the most valuable deposits of iron ore have accumulated in bogs fed by iron-impregnated spring water. in a similar way lime deposits called marl or chalk are made. the soil in fields and gardens city and country teachers are expected to teach classes about the formation and cultivation of soil. it is surprising how much of the needed materials can be brought in by the children, even in the cities. the beginning is a flowering plant growing in a pot. a window box is a small garden. a garden plot is a miniature farm. _materials to collect for study indoors._ a few pieces of different kinds of rock: granite, sandstone, slate; gravelly fragments of each, and finer sand. pebbles from brooks and seashore. samples of clays of different colors, and sands. samples of sandy and clay soils, black pond muck, peat and coal. rock fossils. a box of moist earth with earthworms in it. _keep it moist._ a piece of sod, and a red clover plant with the soil clinging to its roots. _what is soil?_ it is the surface layer of the earth's crust, sometimes too shallow on the rocks to plough, sometimes much deeper. under deep soil lies the "subsoil," usually hard and rarely ploughed. _what is soil made of?_ ground rock materials and decayed remains of animal and plant life. by slow decay the soil becomes rich food for the growing of new plants. wild land grows up to weeds and finally to forests. the soil in fields and gardens is cultivated to make it fertile. plants take fertility from the soil. to maintain the same richness, plant food must be put back into the soil. this is done by deep tillage, and by mixing in with the soil manures, green crops, like clover, and commercial fertilizers. _plants must be made comfortable, and must be fed._ few plants are comfortable in sand. it gets hot, it lets water through, and it shifts in wind and is a poor anchor for roots. clay is so stiff that water cannot easily permeate it; roots have the same trouble to penetrate it and get at the food it is rich in. air cannot get in. sand mixed with clay makes a mellow soil, which lets water and air pass freely through. the roots are more comfortable, and the tiny root hairs can reach the particles of both kinds of mineral food. but the needful third element is decaying plant and animal substances, called "humus." these enrich the soil, but they do a more important thing: their decay hastens the release of plant food from the earthy part of the soil, and they add to it a sticky element which has a wonderful power to attract and hold the water that soaks into the earth. _what is the best garden soil?_ a mixture of sand, clay, and humus is called "loam." if sand predominates, it is a sandy loam--warm, mellow soil. if clay predominates, we have a clay loam--a heavy, rich, but cool soil. all gradations between the two extremes are suited to the needs of crops, from the melons on sandy soil, to celery that prefers deep, cool soil, and cranberries that demand muck--just old humus. _how do plant roots feed in soil?_ by means of delicate root hairs which come into contact with particles of soil around which a film of soil water clings. this fluid dissolves the food, and the root absorbs the fluid. plants can take no food in solid form. hence it is of the greatest importance to have the soil pulverized and spongy, able to absorb and hold the greatest amount of water. the moisture-coated soil particles must have air-spaces between them. air is as necessary to the roots as to the tops of growing plants. _why does the farmer plough and harrow and roll the land?_ to pulverize the soil; to mellow and lighten it; to mix in thoroughly the manure he has spread on it, and to reach, if he can, the deeper layers that have plant food which the roots of his crops have not yet touched. killing weeds is but a minor business, compared with tillage. later, ploughing or cultivating the surface lightly not only destroys the weeds, but it checks the loss of water by evaporation from the cracks that form in dry weather. raking the garden once a day in dry weather does more good than watering it. the "dust mulch" acts as a cool sunguard over the roots. _the process of soil-making._ if the man chopping wood in the yosemite valley looks about him he can see the soil-making forces at work on a grand scale. the bald, steep front of el capitan is of the hardest granite, but it is slowly crumbling, and its fragments are accumulating at the bottom of the long slope. rain and snow fill all crevices in the rocks. frost is a wonderful force in widening these cracks, for water expands when it freezes. the loosened rock masses plough their way down the steep, gathering, as they go, increasing power to tear away any rocks in their path. wind blows finer rock fragments along, and they lodge in cracks. fine dust and the seeds of plants are lodged there. the rocky slopes of the yosemite valley are all more or less covered with trees and shrubs that have come from wind-sown seeds. these plants thrust their roots deeper each year into the rock crevices. the feeding tips of roots secrete acids that eat away lime and other substances that occur in rocks. dead leaves and other discarded portions of the trees rot about their roots, and form soil of increasing depth. the largest trees grow on the rocky soil deposited at the base of the slope. the tree's roots prevent the river from carrying it off. when granite crumbles, its different mineral elements are separated. clear, glassy particles of quartz we call sand. dark particles of feldspar become clay, and may harden into slate. sand may become sandstone. exposed slate and sandstone are crumbled by exposure to wind and frost and moving water, and are deposited again as sand-bars and beds of clay. the most interesting phase of soil study is the discovery of what a work the humble earthworm does in mellowing and enriching the soil. the work of earthworms the farmer and the gardener should expect very poor crops if they planted seed without first ploughing or spading the soil. next, its fine particles must be separated by the breaking of the hard clods. a wise man ploughs heavy soil in the fall. it is caked into great clods which crumble before planting time. the water in the clods freezes in winter. the expansion due to freezing makes this soil water a force that separates the fine particles. so the frost works for the farmer. just under the surface of the soil lives a host of workers which are our patient friends. they work for their living, and are perhaps unconscious of the fact that they are constantly increasing the fertility of the soil. they are the earthworms, also called fishworms, which are distributed all over the world. they are not generally known to farmers and gardeners as friendly, useful creatures, and their services are rarely noticed. we see robins pulling them out of the ground, and we are likely to think the birds are ridding us of a garden pest. what we need is to use our eyes, and to read the wonderful discoveries recorded in a book called "vegetable mould and earthworms," written by charles darwin. the benefits of ploughing and spading are the loosening and pulverizing of the packed earth; the mixing of dead leaves and other vegetation on and near the surface with the more solid earth farther down; the letting in of water and air; and the checking of loss of water through cracks the sun forms by baking the soil dry. the earthworm is a creature of the dark. it cannot see, but it is sufficiently sensitive to light to avoid the sun, the rays of which would shrivel up its moist skin. having no lungs or gills, the worm uses the skin as the breathing organ; and it must be kept moist in order to serve its important use. this is why earthworms are never seen above ground except on rainy days, and never in the top soil if it has become dry. in seasons of little rain, they go down where the earth is moist, and venture to the surface only at night, when dew makes their coming up possible. earthworms have no teeth, but they have a long snout that protrudes beyond the mouth. their food is found on and in the surface soil. they will eat scraps of meat by sucking the juices, and scrape off the pulp of leaves and root vegetables in much the same way. much of their subsistence is upon organic matter that can be extracted from the soil. quantities of earth are swallowed. it is rare that an earthworm is dug up that does not show earth pellets somewhere on their way through the long digestive canal. the rich juices of plant substance are absorbed from these pellets as they pass through the body. earthworms explore the surface of the soil by night, and pick up what they can find of fresh food. nowhere have i heard of them as a nuisance in gardens, but they eagerly feed on bits of meat, especially fat, and on fresh leaves. they drag all such victuals into their burrows, and begin the digestion of the food by pouring on it from their mouths a secretion somewhat like pancreatic juice. the worms honeycomb the earth with their burrows, which are long, winding tubes. in dry or cold weather these burrows may reach eight feet under ground. they run obliquely, as a rule, from the surface, and are lined with a layer of the smooth soil, like soft paste, cast from the body. the lining being spread, the burrow fits the worm's body closely. this enables it to pass quickly from one end to the other, though it must wriggle backward or forward without turning around. at the lower end of the burrow, an enlarged chamber is found, where hibernating worms coil and sleep together in winter. at the top, a lining of dead leaves extends downward for a few inches, and in day time a plug of the same material is the outside door. at night the worm comes to the surface, and casts out the pellets of earth swallowed. the burrow grows in length by the amount of earth scraped off by the long snout and swallowed. the daily amount of excavation done is fairly estimated by the castings observed each morning on the surface. one earthworm's work for the farmer is not very much, but consider how many are at work, and what each one is doing. it is boring holes through the solid earth, and letting in the surface water and the air. it is carrying the lower soil up to the surface, often the stubborn subsoil, that no plough could reach. it is burying and thus hastening the decay of plant fibre, which lightens heavy soil and makes it rich because it is porous. moreover, the earthworms are doing over and over again this work of fining and turning over the soil, which the plough does but seldom. by the continuous carrying up of their castings, the earthworms gradually bury manures spread on the surface. the collapse of their burrows and the making of new ones keep the soil constantly in motion. the particles are being loosened and brought into contact with the soil water, that dissolves, and thus frees for the use of feeding roots, the plant food stored in the rock particles that compose the mineral part of the soil. the weight of earth brought to the surface by worms in the course of a year has been carefully estimated. darwin gives seven to eighteen tons per acre as the lowest and highest reports, based on careful collecting of castings by four observers, working on small areas of totally different soils. in england, earthworms have done a great deal more toward burying boulders and ancient ruins than any other agency. they eagerly burrow under heavy objects, the weight of which causes them to crush the honeycombed earth. undiscouraged, the earthworms repeat their work. "long before man existed, the land was regularly ploughed, and continues still to be ploughed by earthworms. it may be doubted whether there are many other animals which have played so important a part in the history of the world as have these lowly organized creatures." after years of study, charles darwin came to this conclusion. the more we study the lives of these earth-consuming creatures, the more fully do we believe what the great nature student said. the fertile soil is made of rock meal and decayed leaves and roots. only recently have ploughs been invented. but the great forest crops have grown in soil made mellow by the earthworm's ploughing. quiet forces that destroy rocks wind and water are the blustering active agents we see at work tearing down rocks and carrying away their particles. they do the most of this work of levelling the land; but there are quiet forces at work which might not attract our attention at all, and yet, without their help, wind and running water would not accomplish half the work for which they take the credit. the air contains certain destructive gases which by their chemical action separate the particles of the hardest rocks, causing them to crumble. now the wind blows away these crumbling particles, and the solid unchanged rock beneath is again exposed to the crumbling agencies. the changes in temperature between day and night cause rocks to contract and expand, and these changes put a strain upon the mineral particles that compose them. much scaling of rock surfaces is due to these causes. building a fire on top of a rock, and then dashing water upon the heated mass, shatters it in many directions. this process merely intensifies the effect produced by the mild changes of winter and summer. water is present in most rocks, in surprising quantities, often filling the spaces in porous rocks like sandstones. when winter brings the temperature down to the freezing point, the water near the surface of the rock first feels it. ice forms, and every particle of water is swollen by the change. a strain is put upon the mineral particles against which the particles of ice crowd for more room. frost is a very powerful agent in the crumbling of rocks, as well as of stubborn clods of earth. in warm climates, and in desert regions where there is little moisture in the rocks, this destructive action of freezing water is not known. in cold countries, and in high altitudes, where the air is heavy with moisture, its greatest work is done. some kinds of rock decay when they become dry, and resist crumbling better when they absorb a certain amount of moisture. alternate wetting and drying is destructive to certain rocks. one of the unnoticed agents of rock decay is the action of lowly plants. mosses grow upon the faces of rocks, thrusting their tiny root processes into pits they dig deeper by means of acids secreted by the delicate tips. you have seen shaded green patches of lichens, like little rugs, of different shapes, spread on the surface of rocks. but you cannot see so well the work these growths are doing in etching away the surface, and feeding upon the decaying mineral substance. mosses and lichens do a mighty work, with the help of water, in reducing rocks to their original elements, and thus forming soil. no plants but lichens and mosses can grow on the bare faces of rocks. as their root-like processes lengthen and go deeper into the rock face, particles are pried off, and the under-substance is attacked. higher plants then find a footing. have you not seen little trees growing on a patch of moss which gets its food from the air and the rock to which it clings? the spongy moss cushion soaks up the rain and holds it against the rock face. a streak of iron in the rock may cause the water to follow and rust it out, leaving a distinct crevice. now the roots of any plant that happens to be growing on the moss may find a foot-hold in the crack. streaks of lime in a rock readily absorb water, which gradually dissolves and absorbs its particles, inviting the roots to enter these new passages and feed upon the disintegrating minerals. dead leaves decay, and the acids the trickling water absorbs from them are especially active in disintegrating lime rocks. from such small beginnings has resulted the shattering of great rock masses by the growth of plants upon them. tree roots that grow in rock crevices exert a power that is irresistible. the roots of smaller plants do the same great work in a quieter way. when a hurricane or a flood tears down the mountain-side, sweeping everything before it, trees, torn out by the roots, drag great masses of rock and soil into the air, and fling them down the slope. wind and water thus finish the destruction which the humble mosses and lichens began. what seemed an impregnable fortress of granite has crumbled into fragments. its particles are reduced to dust, or are on the way to this condition. the plant food locked up in granite boulders becomes available to hungry roots. forests, grain-fields, and meadows cover the work of destructive agencies with a mantle of green. how rocks are made the granite shaft is made out of the original substance of the earth's crust. its minerals are the elements out of which all of the rock masses of the earth are formed, no matter how different they look from granite. sandstone is made of particles of quartz. clay and slate are made out of feldspar and mica. iron ore comes from the hornblende in granite. the mineral particles, reassembled in different proportions, form all of the different rocks that are known. here in my hand is a piece of pudding-stone. it is made of pebbles of different sizes, each made of different coloured minerals. the pebbles are cemented together with a paste that has hardened into stone. this kind of rock the geologists call _conglomerate_. pudding-stone is the common name, for the pebbles in the pasty matrix certainly do suggest the currants and the raisins that are sprinkled through a christmas pudding. under the seashores there are forming to-day thick beds of sand. the rivers bring the rock material down from the hills, and it is sorted and laid down. the moving water drops the heaviest particles near shore, and carries the finer ones farther out before letting them fall. [illustration: the town of cripple creek, colorado, which has grown up like magic since , covers the richest gold and silver mines in the world] [illustration: the level valley is filled up with fine rock flour washed from the sides of the neighboring mountains] the hard water, that comes through limestone rocks, adds lime in solution to the ocean water. all the shellfish of the sea, and the creatures with bony skeletons, take in the bone-building, shell-making lime with their food. generations of these inhabitants of the sea have died, and their shells and bones have accumulated and been transformed into thick beds of limestone on the ocean floor. this is going on to-day; but the limestone does not accumulate as rapidly as when the ocean teemed with shell-bearing creatures of gigantic size. of these we shall speak in another chapter. the fine dust that is blown into the ocean from the land, and that makes river water muddy, accumulates on the sea bottom as banks of mud, which by the burden of later deposits is converted into clay. sandstone is but the compressed sand-bank. in the study of mountains, geologists have discovered that old seashores were thrown up into the first great ridges that form the backbone of a mountain system. the rocky mountains, and the appalachian system on the east, were made out of thick strata of rocks that had been formed by accumulations of mud and sand--the washings of the land--on the opposite shores of a great mid-continental sea, that stretched from the crest of one great mountain system across to the other, and north and south from the laurentian hills to the gulf of mexico. the great weight of the accumulating layers of rock materials on one side, and the wasted land surfaces on the other, made the sea border a line of greatest weakness in the crust of the earth. the shrinking of the globe underneath caused the break; mashing and folding followed, throwing the ridge above sea-level, and making dry land out of rock waste which had been accumulating, perhaps for millions of years, under the sea. the wrinkling of the earth's crust was the result of crushing forces which produced tremendous heat. streams of lava sprang out through the fissures and poured streams of melted rock down the sides of the fold, quite burying, in many places, the layers of limestone, sandstone, and clay. between the strata of water-formed rocks there were often created chimney-like openings, into which molten rock from below was forced, forming, when cool, veins and dikes of rock material, specimens of the substance of the earth's interior. tremendous pressure and heat, acting upon stratified rocks saturated with water transform them into very different kinds of rock. limestone, subjected to these forces, is changed into marble. clays are transformed into slates. sandstone is changed into quartzite, the sand grains being melted so as to become no longer visible to the naked eye. the anthracite coal of the pennsylvania mountains is the result of heat and pressure acting upon soft coal. associated with these beds of hard coal are beds of black lead, or graphite, the substance used in making "lead" pencils. we believe that the same forces that operated to transform clay rocks into slate, and limestone into marble, transformed soft coal into hard, and hard coal into graphite, in the days when the earth was young. the word _sedimentary_ is applied to rocks which were originally laid down under water, as sediment, brought by running water, or by wind, or by the decay of organic substances. _stratified_ rocks are those which are arranged in layers. sedimentary rocks will fall into this class. _aqueous_ rocks are those which are formed under water. most of the stratified and sedimentary rocks, but not all, may be included under this term. rocks that are made out of fragments of other rocks torn down by the agencies of erosion are called _fragmental_. wind, water, and ice are the three great agencies that wear away the land, bring rock fragments long distances, and deposit them where aqueous rocks are being formed. volcanic eruptions bring material from the earth's interior. this material ranges all the way from huge boulders to the finest impalpable dust, called volcanic ashes. rivers of ice called glaciers crowd against their banks, loosening rock masses and carrying away fragments of all sizes, in their progress down the valley. brooks and rivers carry the pebbles and the larger rock masses they are able to loosen from their walls and beds, and grind them smooth as they move along toward lower levels. the air itself causes rocks to crumble; percolating water robs them of their soluble salts, reducing even solid granite to a loose mass of quartz grains and clay. plants and animals absorb as food the mineral substances of rocks, when they are dissolved in water. they transform these food elements into their own body substance, and finally give back their dead bodies, the mineral substances of which are freed by decay to return to the earth, and become elements of rock again. the decay of rock is well shown by the materials that accumulate at the base of a cliff. angular fragments of all sizes, but all more or less flattened, come from strata of shaly rock, that can be seen jutting out far above. a great deal of this sort of material is found mingled with the soil of the northeastern states. round pebbles in pudding-stone have been formed in brook beds and deposited on beaches where they have become caked in mud and finally consolidated into rock. if the beach chanced to be sandy instead of muddy, a matrix of sandy paste holds the larger pebbles in place. limestone paste cements together the pebbles of limestone conglomerates. in st. augustine many of the houses are built of coquina rock, a mass of broken shells which have become cemented together by lime mud, derived from their own decay. on the slopes of volcanoes, rock fragments of all kinds are cemented together by the flowing lava. so we see that there are pudding-stones of many kinds to be found. if some solvent acid is present in the water that percolates through these rocks it may soften the cement and thus free the pebbles, reducing the conglomerate again to a mere heap of shell fragments, or gravel, or rounded pebbles. the story of rock formation tells how fire and water, and the two combined, have made, and made over, again and again, the substance of the earth's crust. chemical and physical changes constantly tear down some portions of the earth to build up others. the constant, combined effort of wind and water is to level the earth and fill up the ocean bed. rocks are constantly being formed; the changes that have been going on since the world began are still in progress. we can see them all about us on any and every day of our lives. getting acquainted with a river i have two friends whose childhood was spent in a home on the banks of a noble eastern river. their father taught the boy and the girl to row a boat, and later each learned the more difficult art of managing a canoe. on holidays they enjoyed no pleasure so much as a picnic on the river-bank at some point that could be reached by rowing. as they grew older, longer trips were planned, and the river was explored as far as it was navigable by boat or canoe. last summer when vacation came, these two carried out a long-cherished plan to find the beginning of the river--to follow it to its source. so they left home, and canoed up-stream, until the stream became a brook, so shallow they could go no farther. then they followed it on foot--wading, climbing, making little détours, but never losing the little river. at last they came to the beginning of it--a tiny rivulet trickled out of the side of a hill, filling a wooden keg that formed a basin, where thirsty passers-by could stoop and drink. they decided to mark the spring, so that people who found it later, and were refreshed by its clear water, might know that here was born the greatest river of a great state. but they were not the original discoverers. above the spring, a board was nailed to a tree, saying that this is the headwater of the river with the beautiful indian name, susquehanna. it was a dry summer, and the overflow of the basin was almost all drunk up by the thirsty ground. they could scarcely follow it, except by the groove cut by the rivulet in seasons when the flow was greater. they followed the runaway brook, through the grass roots, that almost hid it. as the ground grew steeper, it hurried faster. soon it gathered the water of other springs, which hurried toward it in small rivulets, because its level was lower. water always seeks the lowest level it can find. sometimes marshy spots were reached where water stood in the holes made by the feet of cattle that came there to drink. the water was muddy, and seemed to stand still. but it was settling steadily, and at one side the little river was found, flowing away with the water it drew from the swampy, springy ground. all the mud was gone, now; the water was clear. it flowed in a bed with a stony floor, and there were rough steps where the water fell down in little sheets, forming a waterfall, the first of many that make this river beautiful in the upper half of its course. to get from the high level of that hillside spring to the low level of the sea, the water has to make a fall of twenty-three hundred feet, but it makes the descent gradually. it could not climb over anything, but always found a way to get around the rocks and hills that stood in its way. when the flat marsh land interfered, the water poured in and overflowed the basin at the lowest margin. in the rocky ground the two explorers found that the stream had widened its channel by entering a narrow crevice and wearing away its walls. the continual washing of the water wears away stone. rocks are softened by being wet. streaks of iron in the hardest granite will rust out and let the water in. then the lime in rocks is easily dissolved. every dead leaf the river carried along added an acid to the water, and this made easier the process of dissolving the limestone. every crumbling rock gives the river tools that it uses like hammer and chisel and sandpaper to smooth all the uneven surfaces in its bed, to move stumbling blocks, and to dig the bed deeper and wider. the steeper the slope is, the faster the stream flows, and the larger the rocks it can carry. rocks loosened from the stream bed are rolled along by the current. then bang! against the rocks that are not loose, and often they are able to break them loose. the fine sand is swept along, and its sharp points strike like steel needles, and do a great work in polishing roughness and loosening small particles from the stream bed. the bigger pebbles of the stream have banged against the rock walls, with the same effect, smoothing away unevenness and pounding fragments loose, rolling against one another, and getting their own rough corners worn away. the makers of stone marbles learned their business from a brook. they cut the stone into cubical blocks, and throw them into troughs, into which is poured a stream of running water. the blocks are kept in motion, and the grinding makes each block help the rest to grind off the eight corners and the twelve ridges of each one. the water becomes muddy with the fine particles, just as the drip from a grindstone becomes unclean when an axe is ground. pretty soon all the blocks in the trough are changed into globes--the marbles that children buy at the shops when marble season comes around. i suppose if the troughs are not watched and emptied in time, the marbles would gradually be ground down to the size of peas, then to the size of small bird shot, and finally they would escape as muddy water and fine sand grains. sure it is that the sandy shores that line most rivers are the remnants of hard rocks that have been torn out and ground up by the action of the current. not very many miles from its first waterfall the stream had grown so large that my two friends knew that they would soon find their canoes. the plan now was to float down the curious, winding river and to learn, if the river and the banks could tell them, just why the course was so crooked on the map. they came into a broad, level valley where streams met them, coming out of deep clefts between the hills they were leaving behind them. the banks were pebbly, but blackened with slimy mud that made the water murky. the current swerved from one side to the other, sometimes quite close to the bank, where the river turned and formed a deep bend. on this side the bank was steep, the roots of plants and trees exposed. on the opposite side a muddy bank sloped gently out into the stream. here building up was going on, to offset the tearing down. the sharp bends are made sharper, once the current is deflected from the middle of the stream to one side. at length the loops bend on each other and come so near together that the current breaks through, leaving a semicircular bayou of still water, and the river's course straightened at that place. it must have been in a spring flood that this cut-off was made, and, the break once made was easily widened, for the soil is fine mud which, when soaked, crumbles and dissolves into muddy water. stately and slow that river moves down to the bay, into which it empties its load. the rain that falls on hundreds of square miles of territory flows into the streams that feed this trunk. the little spring that is the headwater of the system is but one of many pockets in the hillsides that hold the water that soaks into the ground and give it out by slow degrees. surface water after a rain flows quickly into the streams. it is the springs that hold back their supply and keep the rivers from running dry in hot weather. do they feel now that they know their river? are they ready to leave it, and explore some other? indeed, no. they are barely introduced to it. all kinds of rivers are shown by the different parts of this one. it is a river of the mountains and of the lowland. it flows through woods and prairies, through rocky passes and reedy flats. it races impetuously in its youth, and plods sedately in later life. the trees and the other plants that shadow this stream, and live by its bounty, are very different in the upland and in the lowland. the scenery along this stream shows endless variety. up yonder all is wild. down here great bridges span the flood, boats of all kinds carry on the commerce between two neighbour cities. a great park comes down to the river-bank on one side. canoes are thick as they can paddle on late summer afternoons. no one can ever really know a river well enough to feel that it is an old story. there is always something new it has to tell its friends. so my two explorers say, and they know far more about their friendly river than i do. the ways of rivers a canal is an artificial river, built to carry boats from one place to another. its course is, as nearly as possible, a straight line between two points. a river, we all agree, is more beautiful than a canal, for it winds in graceful curves, in and out among the hills, its waters seeking the lowest level, always. no artist could lay out curves more beautiful than the river forms. these curves change from year to year, some slowly, some more rapidly. it is not hard to understand just why these changes take place. some rivers are dangerous for boating at certain points. the current is strong, and there are eddies and whirlpools that have to be avoided, or the boat becomes unmanageable. people are drowned each season by trusting themselves to rivers the dangerous tricks of which they do not know. deep holes are washed out of the bed of the stream by whirling eddies. the pot-holes of which people talk are deep, rounded cavities, ground out of the rocky stream-bed by the scouring of sand and loose stones driven by whirling eddies in shallow basins. every year deepens each pot-hole until some change in the stream-bed shifts the eddy to another place. no stream finds its channel ready-made; it makes its own, and constantly changes it. the current swings to one side of the channel, lifting the loose sediment and grinding deeper the bed of the stream. the water lags on the opposite side, and sediment falls to the bottom. so the building-up of one side is going on at the same time that the tearing-down process is being carried on on the other. with the lowering of the bed the river swerves toward one bank, and a hollow is worn by slow degrees. the current swings into this hollow, and in passing out is thrown across the stream to the opposite bank. here its force wears away another hollow; and so it zigzags down-stream. the deeper the hollows, the more curved becomes the course, if the general fall is but moderate. it is toward the lower courses of the stream that the winding becomes more noticeable. the sediment that is carried is deposited at the point where the current is least strong, so that while the outcurves become sharper by the tearing away of the stream's bank, the incurves become sharper by the building up of this bank. the mississippi below memphis is thrown into a wonderful series of curves by the erosion and the deposit caused by the current zigzagging back and forth from one bank to the other. gradually the curves become loops. the river's current finally jumps across the meeting of the curves, and abandons the circular bend. it becomes a bayou or lagoon of still water, while the current flows on in the straightened channel. all rivers that flow through flat, swampy land show these intricate winding channels and many lagoons that have once been curves of the river. no one would ever mistake a river for a lake or any other body of water, yet rivers differ greatly in character. one tears its way along down its steep, rock-encumbered channel between walls that rise as vertical precipices on both sides. the roaming, angry waters are drawn into whirlpools in one place. they lie stagnant as if sulking in another, then leap boisterously over ledges of rock and are churned into creamy foam at the bottom. outside the mountainous part of its course this same river flows broad and calm through a mud-banked channel, cut by tributary streams that draw in the water of low, sloping hills. the missouri is such a wild mountain stream at its headwaters. we who have seen its muddy waters from sioux city to st. louis would hardly believe that its impetuous and picturesque youth could merge into an old age so comfortable and placid and commonplace. this thing is true of all rivers. they flow, gradually or suddenly, from higher to lower levels. to reach the lowest level as soon as possible is the end each river is striving toward. if it could, each river would cut its bed to this depth at the first stage of its course. its tools are the rocks it carries, great and small. the force that uses these tools is the power of falling water, represented by the current of the stream. the upper part of a river such as the missouri or mississippi engages in a campaign of widening and deepening its channel, and carrying away quantities of sediment. the lower reaches of the stream flow through more level country; the current is checked, and a vast burden of sediment is laid down. instead of tearing away its banks and bottom, the river fills up gradually with mud. the current meanders between banks of sediment over a bottom which becomes shallower year by year. the rocky mountains are being carried to the gulf of mexico. the commerce of the river is impeded by mountain débris deposited as mud-banks along the river's lower course. many rivers are quiet and commonplace throughout their length. they flow between low, rounded hills, and are joined by quiet streams, that occupy the separating grooves between the hills. this is the oldest type of river. it has done its work. rainfall and stream-flow have brought the level of the land nearly to the level of the stream. very little more is left to be ground down and carried away. the landscape is beautiful, but it is no longer picturesque. wind and water have smoothed away unevennesses. trees and grass and other vegetation check erosion, and the river has little to do but to carry away the surface water that falls as rain. but suppose our river, flowing gently between its grassy banks, should feel some mighty power lifting it up, with all its neighbour hills and valleys, to form a wrinkle in the still unstable crust of the earth. away off at the river's mouth the level may not have changed, or that region may have been depressed instead of elevated by the shrinking process. suppose the great upheaval has not severed the upper from the lower courses of the stream. with tremendous force and speed, the current flows from the higher levels to the lower. the river in the highlands strikes hard to reach the level of its mouth. it grinds with all its might, and all its rocky tools, upon its bed. all the mud is scoured out, and then the underlying rocks are attacked. if these rocks are soft and easily worn away, the channel deepens rapidly. one after another the alternating layers are excavated, and the river flows in a canyon which deepens more and more. as the level is lowered, the current of the stream becomes slower and the cutting away of its bed less rapid. the stream is content to flow gently, for it has almost reached the old level, on which it flowed before the valley became a ridge or table-land. the rivers that flow in canyons have been thousands of years in carving out their channels, yet they are newer, geologically speaking, than the streams that drain the level prairie country. the earth has risen, and the canyons have been carved since the prairies became rolling, level ground. [illustration: this little pond is a basin hollowed by the same glacier that scattered the stones and rounded the hills] [illustration: every stream is wearing away its banks, while trees and grass blades are holding on to the soil with all their roots] the colorado river flows through a canyon with walls that in places present sheer vertical faces a mile in depth, and so smooth that no trail can be found by which to reach from top to bottom. the region has but slight erosion by wind, and practically none by rain. the local rainfall is very slight. so the river is the one force that has acted to cut down the rocks, and its force is all expended in the narrow area of its own bed. had frequent rains been the rule on the colorado plateau, the angles of the mesas would have been rounded into hills of the familiar kind so constantly a part of the landscape in the eastern half of the continent. the colorado is an ancient river which has to carry away the store of moisture that comes from the pacific ocean and falls as snow on the high peaks of the rocky mountains. similar river gorges with similar stories to tell are the arkansas, the platte, and the yellowstone. all cut their channels unaided through regions of little rain. when the earth's crust is thrown up in mountain folds, and between them valleys are formed, the level of rivers is sometimes lowered and the rapidity of their flow is checked. a stream which has torn down its walls at a rapid rate becomes a sluggish water-course, its current clogged with sediment, which it has no power to carry farther. when such a river begins to build and obstruct its own waters it bars its progress and may form a lake as the outlet of its tributary streams. many ancient rivers have been utterly changed and some obliterated by general movements of the earth's crust. the story of a pond look out of the car window as you cross a flat stretch of new prairie country, and you see a great many little ponds of water dotting the green landscape. forty years ago iowa was a good place to see ponds of all shapes and sizes. the copious rainfall of the early spring gathered in the hollows of the land, and the stiff clay subsoil prevented the water from soaking quickly into the ground. the ponds might dry away during the hot, dry summer, leaving a baked clay basin, checked with an intricate system of cracks. or if rains were frequent and heavy, they might keep full to the brim throughout the season. tall bulrushes stood around the margins of the largest ponds, and water-lilies blossomed on the surface during the summer. the bass and the treble of the spring chorus were made by frogs and toads and little hylas, all of which resorted to the ponds to lay their eggs, in coiled ropes or spongy masses, according to their various family traditions. on many a spring night my zoölogy class and i have visited the squashy margins of these ponds, and, by the light of a lantern, seen singing toads and frogs sitting on bare hummocks of grass roots that stood above the water-line. the throat of each musician was puffed out into a bag about the size and shape of a small hen's egg; and all were singing for dear life, and making a din that was almost ear-splitting at close range. so great was the self-absorption of these singers that we could approach them, daze them with the light of the lantern, and capture any number of them with our long-handled nets before they noticed us. but it was not easy to persuade them to sing in captivity, no matter how many of the comforts of home we provided in the school aquariums. so, after some very interesting nature studies, we always carried them back and liberated them, where they could rejoin their kinsfolk and neighbours. it was when we were scraping the mud from our rubber boots that we realized the character of the bottoms of our prairie ponds. the slimy black deposit was made partly of the clay bottom, but largely of decaying roots and tops of water plants of various kinds. whenever it rained or the wind blew hard, the bottom was stirred enough to make the water muddy; and on the quietest days a pail of pond water had a tinge of brown because there were always decaying leaves and other rubbish to stain its purity. the farmers drained the ponds as fast as they were able, carrying the water, by open ditches first, and later by underground tile drains, to lower levels. finally these trunk drain pipes discharged the water into streams or lakes. to-day a large proportion of the pond areas of iowa has disappeared; the hollow tile of terra-cotta has been the most efficient means of converting the waste land, covered by ponds, into fertile fields. but the ponds that have not been drained are smaller than they used to be, and are on the straight road to extinction. this process one can see at any time by visiting a pond. every year a crop of reeds and a dozen other species of vigorous water plants dies at the top and adds the substance of their summer growth to the dust and other refuse that gathers in the bottom of the pond. each spring roots and seeds send up another crop, if possible more vigorous than the last, and this top growth in turn dies and lies upon the bottom. the pond level varies with the rainfall of the years, but it averages a certain depth, from which something is each year subtracted by the accumulations of rotting vegetable matter in the bottom. evaporation lowers the water-level, especially in hot, dry summers. from year to year the water plants draw in to form a smaller circle, the grassy meadow land encroaches on all sides. the end of the story is the filling up of the pond basin with the rotting substance of its own vegetation. this is what is happening to ponds and inland marshes by slow degrees. the tile drain pipes obliterate the pond in a single season. nature is more deliberate. she may require a hundred years to fill up a single pond which the farmer can rid himself of by a few days of work and a few rods of tiling. the riddle of the lost rocks outside of my window two robins are building a nest in the crotch of a blossoming red maple tree. and just across the hedge, men are digging a big square hole in the ground--the cellar of our neighbour's new house. it looks now as if the robins would get their house built first, for they need but one room, and they do not trouble about a cellar. i shall watch both houses as they grow through the breezy march days. the brown sod was first torn up by a plough, which uncovered the red new jersey soil. two men, with a team hitched to a scraper, have carried load after load of the loose earth to a heap on the back of the lot, while two other men with pickaxes dug into the hard subsoil, loosening it, so that the scraper could scoop it up. this subsoil is heavy, like clay, and it breaks apart into hard clods. at the surface the men found a network of tree roots, about which the soil easily crumbled. often i hear a sharp, metallic stroke, unlike the dull sound of the picks striking into the earth. the digger has struck a stone, and he must work around it, pry it up and lift it out of the way. a row of these stones is seen at one side of the cellar hole, ranged along the bank. they are all different in size and shape, and red with clay, so i can't tell what they are made of. but from this distance i see plainly that they are irregular in form and have no sharp corners. the soil strewn along the lot by the scraper is full of stones, mostly irregular, but some rounded; some are as big as your head, others grade down to the sizes of marbles. when i went down and examined this red earth, i found pebbles of all shapes and sizes, gravel in with the clay, and grains of sand. this rock-sprinkled soil in new jersey is very much like soil which i know very well in iowa; it looks different in colour, but those pebbles and rock fragments must be explained in the same way here as there. these are not native stones, the outcrop of near-by hillsides, but strangers in this region. the stones in iowa soil are also imported. the prairie land of iowa has not many big rocks on the surface, yet enough of them to make trouble. the man who was ploughing kept a sharp lookout, and swung his plough point away from a buried rock that showed above ground, lest it should break the steel blade. one of the farmer's jobs for the less busy season was to go out with sledge and dynamite sticks, and blast into fragments the buried boulders too large to move. sometimes building a hot fire on the top of it, and throwing on water, would crack the stubborn "dornick" into pieces small enough to be loaded on stone-boats. i remember when the last giant boulder whose buried bulk scarcely showed at the surface, was fractured by dynamite. its total weight proved to be many tons. we hauled the pieces to the great stone pile which furnished materials for walling the sides of a deep well and for laying the foundation of the new house. yet for years stones have been accumulating, all of them turned out of the same farm, when pastures and swampy land came under the plough. draw a line on the map from new york to st. louis, and then turn northward a little and extend it to the yellowstone park. the boulder-strewn states lie north of this line, and are not found south of it, anywhere. canada has boulders just like those of our northern states. the same power scattered them over all of the vast northern half of north america and a large part of europe. what explanation is there for this extensive distribution of unsorted débris? the question answered the rocks tell their own story, partly, but not wholly. they told just enough to keep the early geologists guessing; and only very recently has the guessing come upon the truth. these things the rocks told: . we have come from a distance. . we have had our sharp corners worn off. . many of us have deep scratches on our sides. . at various places we have been dumped in long ridges, mixed with much earth. . a big boulder is often balanced on another one. the first thing the geologist noted was the fact that these boulders are strangers--that is, they are not the native rocks that outcrop on hillsides and on mountain slopes near where they are found. far to the north are beds of rock from which this débris undoubtedly came. could a flood have scattered them as they are found? no, for water sorts the rock débris it deposits, and it rounds and polishes rock fragments, instead of scratching and grooving them and leaving them angular, as these are. professor agassiz went to switzerland and studied the glaciers. he found unsorted rock fragments where the glacier's nose melted, and let them fall. they were worn and scratched and grooved, by being frozen into the ice, and dragged over the rocky bed of the stream. the rocky walls of the valley were scored by the glacier's tools. rounded domes of rock jutted out of the ground, in the paths of the ice streams, just like the granite outcrop in central park in new york, and many others in the region of scattered boulders. after long studies in europe and in north america, professor agassiz declared his belief that a great ice-sheet once covered the northern half of both countries, rounding the hills, scooping out the valleys and lake basins, and scattering the boulders, gravel, and clay, as it gradually melted away. the belief of professor agassiz was not accepted at once, but further studies prove that he guessed the riddle of the boulders. the rich soil of the northern states is the glacial drift--the mixture of rock fragments of all sizes with fine boulder clay, left by the gradual melting of the great ice-sheet as it retreated northward at the end of the "glacial epoch." glaciers among the alps switzerland is a little country without any seacoast, mountainous, with steep, lofty peaks, and narrow valleys. the climate is cool and moist, and snow falls the year round on the mountain slopes. a snow-cap covers the lower peaks and ridges. above the level of nine thousand feet the bare peaks rise into a dry atmosphere; but below this altitude, and above the six thousand-foot mark, lies the belt of greatest snowfall. peaks between six and nine thousand feet high are buried under the alpine snow-field, which adds thickness with each storm, and is drained away to feed the rushing mountain streams in the lower valleys. the snow that falls on the steep, smooth slope clings at first; but as the thickness and the weight of these snow banks increase, their hold on the slope weakens. they may slip off, at any moment. the village at the foot of the slope is in danger of being buried under a snow-slide, which people call an avalanche. "challanche" is another name for it. the hunter on the snow-clad mountains dares not shout for fear that his voice, reëchoing among the silent mountains, may start an avalanche on its deadly plunge into the valley. on the surface of the snow-field, light snow-flakes rest. under them the snow is packed closer. deeper down, the snow is granular, like pellets of ice; and still under this is ice, made of snow under pressure. the weight of the accumulated snow presses the underlying ice out into the valleys. these streams are the glaciers--rivers of ice. the glaciers of the alps vary in length from five to fifteen miles, from one to three miles in width, and from two hundred to six hundred feet in thickness. they flow at the rate of from one to three feet a day, going faster on the steeper slopes. it is hard to believe that any substance as solid and brittle as ice can flow. its movement is like that of stiff molasses, or wax, or pitch. the tremendous pressure of the snow-field pushes the mass of ice out into the valleys, and its own weight, combined with the constant pressure from behind, keeps it moving. the glacier's progress is hindered by the uneven walls and bed of the valley, and by any decrease in the slope of the bed. when a flat, broad area is reached, a lake of ice may be formed. these are not frequent in the alps. the water near the banks and at the bottom of a river does not flow as swiftly as in the middle and at the surface of the stream. the flow of ice in a glacier is just so. friction with the banks and bottom retards the ice while the middle parts go forward, melting under the strain, and freezing again. there is a constant readjusting of particles, which does not affect the solidity of the mass. the ice moulds itself over any unevenness in its bed if it cannot remove the obstruction. the drop which would cause a small waterfall in a river, makes a bend in the thick body of the ice river. great cracks, called _crevasses_, are made at the surface, along the line of the bend. the width of the v-shaped openings depends upon the depth of the glacier and the sharpness of the bend that causes the breaks. rocky ridges in the bed of the ice-stream may cause crevasses that run lengthwise of the glacier. snow may fill these chasms or bridge them over. the hunter or the tourist who ventures on the glacier is in constant danger, unless he sees solid ice under him. men rope themselves together in climbing over perilous places, so that if one slips into a crevasse his mates can save him. a glacier tears away and carries away quantities of rock and earth that form the walls of its bed. as the valley narrows, tremendous pressure crowds the ice against the sides, tearing trees out by the roots and causing rock masses to fall on the top of the glacier, or to be dragged along frozen solidly into its sides. the weight of the ice bears on the bed of the glacier, and its progress crowds irresistibly against all loose rock material. the glacier's tools are the rocks it carries frozen into its icy walls and bottom. these rocks rub against the walls, grinding off débris which is pushed or carried along. no matter how heavy the boulders are that fall in the way of the ice river, the ice carries them along. it cannot drop them as a river of water would do. slowly they travel, and finally stop where the nose of the glacier melts and leaves all débris that the mountain stream, fed by the melting of the ice, cannot carry away. the bedrock under a glacier is scraped and ground and scored by the glacier's tools--the rock fragments frozen into the bottom of the ice. these rocks are worn away by constant grinding, just as a steel knife becomes thin and narrow by use. scratches and scorings and polished surfaces are found in all rocks that pass one another in close contact. its worn-out tools the glacier drops at the point where its ice melts. this great, unsorted mass of rock meal and coarser débris the stream is gradually scattering down the valley. the name "moraine" has been given to the earth rubbish a glacier collects and finally dumps. the _top moraine_ is at the surface of the ice. the _lateral moraines_, one at each side, are the débris gathered from the sides of the valley. the _ground moraine_ is what débris the ice pushes and drags along on the bottom. the _terminal moraine_ is the dumping-ground of this mass of material, where the ice river melts. glaciers, like other rivers, often have tributary streams. a _median moraine_, seen as a dark streak running lengthwise on the surface of a glacier, means that two branch glaciers have united to form this one. go back far enough and you will reach the place where the two streams come together. the two lateral moraines that join form the middle line of débris, the median moraine. three ice-streams joined produce two top moraines. they locate the lateral moraines of the middle glacier. the surface of a glacier is often a mass of broken and rough ice, forming a series of pits and pinnacles that make crossing impossible. the sun melts the surface, forming pools and percolating streams of water, that honeycomb the mass. underneath, the ice is tunnelled, and a rushing stream flows out under the end of the glacier. it is not clear, but black with mud, called _boulder clay_, or _till_, made of ground rock, and mixed with fragments of all shapes and sizes. this is the meal from the glacier's mill, dumped where the water can sift it. "balanced rocks" are boulders, one upon another, that once lay on a glacier, and were left in this strange, unstable position when the supporting ice walls melted away from them. in bronx park in new york the "rocking stone" always attracts attention. the glacier that lodged it there, also rounded the granite dome in central park and scattered the rock-strewn boulder clay on long island. doubtless in an earlier day the edges of this glacier were thrust out into the atlantic, not far from the great south bay, and icebergs broke off and floated away. [illustration: potsdam sandstone showing ripple marks] [illustration: _by permission of the american museum of natural history_ glacial striæ on lower helderberg limestone] [illustration: glacial grooves in the south meadow, central park, new york] [illustration: _by permission of the american museum of natural history_ mt. tom, west d st., new york] glaciers are small to-day compared with what they were long ago, in europe and in america. the climate became warmer, and the ice-cap retreated. old moraines show that the ice rivers of the alps once came much farther down the valleys than they do now. smooth, deeply scored domes of rock, the one in central park and the bald head of mount tom, are just like those that lie in alpine valleys from which the glaciers have long ago retreated. there are old moraines far up the sides of valleys, showing that once the glaciers were far deeper than now. no other power could have brought rocks from strata higher up the mountains, and lodged them thus. nearer home, mt. shasta and mt. rainier still have glaciers that have dwindled in size, until they bear little comparison to the gigantic ice-streams that once filled the smooth beds their puny successors flow into. remnants of glaciers lie in the hollows of the sierras. we must go north to find the snow-fields of alaska and glaciers worthy to be compared with those ancient ice rivers whose work is plainly to be seen, though they are gone. the great ice-sheet greenland is green only along its southern edge, and only in summer, so its name is misleading. it is a frozen continent lying under a great ice-cap, which covers , square miles and is several thousand feet in thickness. the top of this icy table-land rises from five thousand to ten thousand feet above the sea-level. the long, cold winters are marked by great snowfall, and the drifts do not have time to melt during the short summer; and so they keep getting deeper and deeper. streams of ice flow down the steeps into the sea, and break off by their weight when they are pushed out into the water. these are the icebergs which float off into the north atlantic, and are often seen by passengers on transatlantic steamers. long ago greenland better deserved its name. explorers who have climbed the mountain steeps that guard the unknown ice-fields of the interior have discovered, a thousand feet above the sea-level, an ancient beach, strewn with shells of molluscs like those which now inhabit salt water, and skeletons of fishes lie buried in the sand. it is impossible to think that the ocean has subsided. the only explanation that accounts for the ancient beach, high and dry on the side of greenland's icy mountain is that the continent has been lifted a thousand feet above its former level. this is an accepted fact. we know that climate changes with changed altitude as well as latitude. going up the side of a mountain, even in tropical regions, we may reach the snow-line in the middle of summer. magnolia trees and tree ferns once grew luxuriantly in greenland forests. their fossil remains have been found in the rocks. this was long before the continent was lifted into the altitude of ice and snow. and it is believed that the climate of northern latitudes has become more severe than formerly from other causes. it is possible that the earth's orbit has gradually changed in form and position. if greenland should ever subside until the ancient beach rests again at sea-level, the secrets of that unknown land would be revealed by the melting of the glacial sheet that overspreads it. possibly it would turn out to be a mere flock of islands. we can only guess. north america had, not so long ago, two-thirds of its area covered with an ice-sheet like that of greenland, and a climate as cold as greenland's. at this time the land was lifted two to three thousand feet higher than its present level. all of the rain fell as snow, and the ice accumulated and became thicker year by year. instead of glaciers filling the gorges, a great ice flood covered all the land, and pushed southward as far as the ohio river on the east and yellowstone park in the west. the rocky mountains and some parts of the appalachian system accumulated snow and formed local glaciers, separated from the vast ice-sheet. the unstable crust of the earth began to sink at length, and gradually the ice-sheet's progress southward was checked, and it began to recede by melting. all along the borders of this great fan-shaped ice-field water accumulated from the melting, and flooded the streams which drained it to the atlantic and the gulf. icebergs broken off of the edge of the retiring ice-sheet floated in a great inland sea. the land sank lower and lower until the general level was five hundred to one thousand feet lower than it now is. the climate became correspondingly warm, and the icebergs melted away. then the land rose again, and in time the inland sea was drained away into the ocean, except for the waters that remained in thousands of lakes great and small that now occupy the region covered by the ice. ancient sea beaches mark the level of high water at the time that the flood followed the melting ice. on the shores of lake champlain, but nearly five hundred feet higher than the present level of the lake, curious geologists have found many kinds of marine shells on a well-marked old sea beach. the members of one exploring party in the same region were surprised and delighted to come by digging upon the skeleton of a whale that had drifted ashore in the ancient days when the inland sea joined the atlantic. lake ontario's ancient beach is five hundred feet above the present water-level; lake erie's is two hundred fifty feet above it; lake superior's three hundred thirty feet higher than the present beach. no doubt when the water stood at the highest level, the great lakes formed one single sheet of water which settled to a lower level as the rivers flowing south cut their channels deep enough to draw off the water toward the gulf. lake winnipeg is now the small remnant of a vast lake the shores of which have been traced. the minnesota river finally made its way into the mississippi and drained this great area the stranded beaches of which still remain. the name of agassiz has been given to the ancient lake formed by the glacial flood and drained away thousands of years ago but not until it had built the terraced beach which locates it on the geological map of the region. when the ice-sheet came down from the north it dragged along all of the soil and loose rock material that lay in its path. with the boulders frozen into its lower surface it scratched and grooved the firm bedrock over which it slid, and rounded it to a smooth and billowy surface. the progress of the ice-sheet was southward, but it spread like a fan so that its widening border turned to east and west. when it reached its southernmost limit and began to melt, it laid down a great ridge of unsorted rock material, remnants of which remain to this day,--the terminal moraine of the ancient ice-sheet. the line of this ancient deposit starts on long island, crosses new jersey and pennsylvania, then dips southward, following the general course of the ohio river to its mouth, forming bluffs in southern ohio, indiana, and illinois. the line bends upward as it crosses central missouri, a corner of kansas, and eastern nebraska, parallel with the course of the missouri. as the ice-sheet melted, boulders were dropped all over the northern states and canada. these were both angular and rounded. in some places they are scattered thickly over the surface and are so numerous as to be a great hindrance to agriculture. in many places great boulders of thousands of tons weight are perched on very slight foundations, just where they lodged when the ice went off and left them, after carrying them hundreds of miles. around them are scattered quantities of loose rock material, not scored or ground as are those which were carried on the under-surface of the glacial ice. these unscarred fragments rode on the top of the ice. they were a part of the top moraine of the glacial sheet. the finest material deposited is rock meal, ground by the great glacial mill, and called "boulder clay." it is a stiff, dense, stony paste in which boulders of all sizes, gravel, pebbles, and cobblestones are cemented. the "drift" of the ice-sheet is the rubbish, coarse and fine, it left behind as it retreated. below the ohio river there is a deep soil produced by the decay of rocks that lie under it. north of ohio is spread that peculiar mixture of earth and rock fragments which was transported from the north and spread over the land which the ice-sheet swept bare and ground smooth and polished. the drift has been washed away in places by the floods that followed the ice. granite domes are thus exposed, the grooves and scratches of which tell in what direction the ice flood was travelling. miles away from that scored granite, but in the same direction as the scratches, scattered fragments of the same foundation rock cover fields and meadows. thus, much of the drift material can be traced to its original home, and the course of the ice-sheet can be determined. many immense boulders the home of which was in the northern highlands of canada rode southward, frozen into icebergs that floated in the great inland sea. great quantities of débris were added to the original glacial drift through the agency of these floating ice masses, which melted by slow degrees. following some lost rivers what would you think if the boat in which you were floating down a pleasant river should suddenly grate upon sand, and you should look over the gunwale and find that here the waters sank out of sight, the river ended? i believe you would rub your eyes, and feel sure that you were dreaming. do not all rivers flow along their beds, growing larger with every mile, and finally empty their waters into a sea, or bay, or lake, or flow into some larger stream? this is the way of most rivers, but there are exceptions. in the far west there are some great rivers that absolutely disappear before they reach a larger body of water. they simply sink away into the sand, and sometimes reappear to finish their courses after flowing underground for miles. do you know the name of one great western river of which i am thinking? is there any stream in your neighbourhood which has such peculiar ways? down in kentucky there is a region where, it is said, one may walk fifty miles without crossing running water. in the middle of our country, in the region of plentiful rainfall, and in a state covered with beautiful woodlands and famous for blue grass and other grain crops, it is amazing that, over a large area, brooks and larger streams are lacking. in most of the state there is plenty of water flowing in streams like those in other parts of the eastern half of the united states. in the near neighbourhood of this peculiar section of the state the streams come to an end suddenly, pouring their water into funnel-shaped depressions of the ground called sink-holes. after a heavy rain the surface water, accumulating in rivulets, may also be traced to small depressions which seem like leaks in the earth's crust, into which the water trickles and disappears. it must have been noticed by the early settlers who came over the mountains from the eastern colonies, and settled in the new, wild, hilly country, which they called kentucky. the first settlers built their log cabins along the streams they found, and shot deer and wild turkey and other game that was plentiful in the woods. the deer showed them where salt was to be found in earthy deposits near the streams; for salt is necessary to every creature. deer trails led from many directions to the "salt licks" which the wild animals visited frequently. perhaps the same pioneers who dug the salt out of the earth found likewise deposits of _nitre_, called also _saltpetre_, a very precious mineral, for it is one of the elements necessary in the manufacture of gunpowder. with the indians all about him, and often showing themselves unfriendly, the pioneer counted gunpowder a necessity of life. he relied on his gun to defend and to feed his family. there were men among those first settlers who knew how to make gunpowder, and saltpetre was one of the things that had to be carried across the mountains into kentucky, until they found it in the hills. no wonder that prospectors went about looking for nitre beds in the overhanging ledges of rocks along stream-beds. in such situations the deposits of nitre were found. the earth was washed in troughs of running water to remove the clayey impurity. after a filtering through wood-ashes, the water which held the nitre in solution was boiled down, and left to evaporate, after which the crystals of saltpetre remained. solid masses of saltpetre weighing hundreds of pounds were sometimes found in protected corners under shelving rocks. it was no doubt in the fascinating hunt for lumps of this pure nitre that the early prospectors discovered that the streams which disappeared into the sink-holes made their way into caverns underground. digging in the sides of ravines often made the earthy wall cave in, and the surprised prospector stood at the door of a cavern. the discoverer of a cave had hopes that by entering he might find nitre beds richer than those he could uncover on the surface, and this often turned out to be true. the hope of finding precious metals and beds of iron ore also encouraged the exploration of these caves. by the time the war of was declared, the mining of saltpetre was a good-sized industry in kentucky. most of the mineral was taken out of small caves, and shipped, when purified, over the mountains, on mule-back by trails, and in carts over good roads that were built on purpose to bring this mineral product to market. as long as war threatened the country, the government was ready to buy all the saltpetre the kentucky frontiersmen could produce. and the miners were constantly in search of richer beds that promised better returns for their labour. it was this search that led to the exploration of the caves discovered, although the explorer took his life in his hands when he left the daylight behind him and plunged into the under-world. not all lost rivers tell as interesting stories or reveal as valuable secrets as did those the neighbours of daniel boone traced along their dark passages underground, and finally saw emerge as hillside springs, in many cases, to feed kentucky rivers. but it is plain that no river sinks from sight unless it finds porous or honeycombed rocks that let it through. the water seeks the nearest and easiest route to the sea. its weight presses toward the lowest level, always. the more water absorbs of acid, the more powerfully does it attack and carry away the substance of lime rocks through which it passes. the mammoth cave of kentucky there is no more fertile soil in the country than that of the famous blue grass region of kentucky. the surface soil rests upon a deep foundation of limestone rocks, and very gradually the plant food locked up in these underlying strata is pulled up to the surface by the soil water, and greedily appropriated by the roots of the plants. part of the water of the abundant rainfall of this region soaks into the layers of the lime rock, carrying various acids in solution which give it power to dissolve the limestone particles, and thus to make its way easily through comparatively porous rock to the very depths of the earth. so it has come about that the surface of the earth is undermined. vast empty chambers have been carved by the patient work of trickling water, which has carried away the lime that once formed solid and continuous layers of the earth's crust. we must believe that the work has taken thousands of years, at least, for no perceptible change has come to these wonderful caves since the discovery and exploration of them a century and more ago. the streams that flow into the region of these caves disappear suddenly into sink-holes and flow through caverns. after wearing away their subterranean channels, leaping down from one level to another, forming waterfalls and lakes, some emerge finally through hillsides in the form of springs. the cavern region of kentucky covers eight thousand square miles. the underground chambers found there are in the limestone rock which varies from ten to four hundred feet in thickness, and averages a little less than two hundred feet. over this territory the number of sink-holes average one hundred to the square mile; and the streams that have poured their water into these basins have made a network of open caverns one hundred thousand miles in length. a great many small caverns have been thoroughly explored and are famous for their beauty. the diamond cave is one of the most splendid, for it is lined with walls and pillars of alabaster that sparkle in the torchlight with crystals that look like veritable diamonds. beautiful springs and waterfalls are found in many caves, but the grandest of all is the mammoth cave, beside which no other is counted worthy to be compared. great tales the miners told of the wonder and the beauty of these caverns, the walls of which were supported by arching alabaster columns and wonderful domes, of indescribable beauty of form and colouring. in , the year that washington died, a pioneer discovered the entrance to a cave, the size and beauty of which surpassed anything he had seen before. after exploring it for a short distance he returned home and took his whole family with him to enjoy the first view of the wonderful cavern he had discovered. they carried pine knots and a lighted torch, by which they made their way for some distance, but the torch was accidentally extinguished and they groped their way in darkness and missed the entrance. without anything to guide them, they wandered in darkness for three days, and were almost dead when at last they stumbled upon the exit. this is the doorway of the mammoth cave of kentucky, one of the wonders of the world. this was a terrible experience. the next persons who attempted to explore the new cave were better provisioned against the chance of spending some time underground. the pioneers found rich deposits of nitre in the "great cave," as they called it. scientists visited it and explored many of its chambers. the reputation of this cavern has been spread by thousands of visitors who have come from all over the world to see it. the cave has not yet been completely explored. the regular tours, on which the guides conduct visitors, cover but a small part of the one hundred and fifty miles measured by the two hundred or more avenues. the passages wind in and out, crossing each other, sometimes at different levels, and forming a network of avenues in which the unaccustomed traveller would surely be lost. the old guides know every inch of their regular course, and their quaint and edifying talk adds greatly to the pleasure of the visitors. from the hotel, parties are organized for ten o'clock in the morning and seven o'clock in the evening. each visitor is provided with a lard-oil lamp. the guide carries a flask of oil and plenty of matches. no special garb is necessary, though people usually dress for comfort, and wear easy shoes. the temperature of the cave is uniform winter and summer, varying between fifty-three and fifty-four degrees fahrenheit. the cave entrance is an arch of seventy-foot span in the hillside. a winding flight of seventy stone steps leads the party around a waterfall, into a great chamber under the rocks. then the way goes through a narrow passage, where the guide unlocks an iron gate to let them in. the visitors now leave all thoughts of daylight behind, for the breeze that put out their lights as they entered the cave is past, and they stand in the rotunda, a vast high-ceilinged chamber, silent and impressive, with walls of creamy limestone, encrusted with gypsum, which has been stained black by manganese. from the vestibule on, each passage and each room has a name, based upon some historic event or some fancied resemblance. the giant's coffin is a great kite-shaped rock lying in one of the rooms of the cave. the star chamber has a wonderful crystal-studded dome in which the guide produces the effect of a sunrise by burning coloured lights. bonfires built at suitable points produce wonderful shadow effects, which are like nothing else in the world. the old saltpetre vats which the visitors pass in taking the "long route" through the cave, point them back to the days during the war of , when this valuable mineral was extracted from the earth in the floor of the cave. the industry greatly enriched the thrifty owners of the cave, but the works were abandoned after peace was declared. it must be a wonderful experience to walk steadily for nine hours over the long route, for so pure is the air and so wonderful is the scenery that people rarely complain of fatigue when the experience is over. there is no dust on the floors of these subterranean chambers, and they are not damp except near places where water trickles, here and there, in rivulets and cascades. pools of water at the bottoms of pits so deep that a lighted torch requires several seconds to reach the bottom, and rivers and lakes of considerable size, show where some of the surface water goes to. a strange underground suction creates whirlpools in some of these streams. people go in boats holding twenty passengers for a row on echo river, and the guide dips up with a net the blind fish and crayfish and cave lizards which inhabit these subterranean waters. the echoes in various chambers of the mammoth cave are remarkable. in some of them a song by a single voice comes back with full chords, as if several voices carried the different parts. the single notes of flute and cornet are returned with the same beautiful harmonies. a pistol shot is given back a dozen times, the sound rebounding like a ball from rock to rock of the arching walls. the vibrations of the water made by the rower's paddles reëcho in sounds like bell notes, and they are multiplied into harmonies that suggest the chimes in the belfry of a cathedral. the walls of various chambers differ from each other according to the minerals that compose them. some are creamy white limestone arches, some are walled with black gypsum, some are hung with great curtains of stalagmites, solid but suggesting the lightness and grace of folds of crêpe. under such hangings the floor is built up in stalactites. the mineral-laden water, the constant drip of which has produced a hanging, icicle-like stalagmite, has built up the stalactite to meet it. probably nothing is more beautiful than the flower-like crystals that bloom all over the walls of a chamber called "mary's bower." the floor, even, sparkles with jewels that have fallen from the wonderful and delicate flower clusters built from deposits of the lime-laden water which goes on building and replacing the bits that fall. "martha's vineyard" is decorated with nodules, like bunches of grapes, that glisten as if the dew were on them. the white gypsum in some caves makes the walls look as if they were carved out of snow. still others have clear, transparent crystals that make them gleam in the torches' light as if the walls were encrusted with diamonds. the cave region of indiana is also famous. the great wyandotte cave in crawford county is the most noted of many similar caverns. in some of the chambers, bats are found clinging to the ceiling, heads downward, like swarms of bees. the caverns of luray, in virginia, are complex and wonderful in their structure, and famous for the beautiful stalactites and stalagmites they contain. but there is no cave in this country so wonderful and so grand in its dimensions as the mammoth cave in kentucky. land-building by rivers once a year, when the rainy season comes in the mountainous country south of egypt, the old nile floods its banks and spreads its slimy waters over the land, covering the low plains to the very edge of the sahara desert. the people know it is coming, and are prepared for this flood. we should think such an overflow of our nearest river a monstrous calamity, but the egyptians bless the river which blesses them. they know that without the nile's overflow their country would be added to the desert of sahara. in a short time after the overflow, the river reaches its highest point and begins to ebb. canals lying parallel to its course are filled with water which is saved for use in the hot, dry summer. as the flood goes down, a deposit of slimy mud lies as a rich fertilizer on the land. it is this and the water which the earth has absorbed that make egypt one of the most fertile agricultural countries in the world. the region covered by the nile's overflow is the flood plain of this river. on this plain the pyramids, the sphinx, and other famous monuments of egypt stand. the statue of rameses ii. built , years ago, has its base buried nine feet deep in the rich soil made of nile sediment. a well dug in this region goes through forty feet of this soil before striking the underlying sand. how many years ago did the first nile overflow take place? we may begin our calculation by finding out the average yearly deposit. it is a slow process that accumulates but nine feet in , years. if you were in egypt when the nile went back into its banks, you would see that the scum it leaves in a single overflow adds not a great deal to the thickness of the soil. possibly floods have varied in their deposits from year to year, so that any calculation of the time it took to build that forty feet of surface soil must be but a rough estimate. this much we know: it has been an uninterrupted process which has taken place within the present geological epoch, "the age of man." not all the rich sediment the nile brings down is left on the level flood plain along its course. a vast quantity is dumped at the river's mouth, where the tides of the mediterranean check the river's current. thus the great delta is formed. the broad river splits into many mouths that spread out like a fan and build higher and broader each year the mud-banks between the streams. upper egypt consists of river swamps. lower egypt, from cairo to the sea, is the delta built by the river itself on sea bottom. from the head of the delta, where the river commences to divide, to the sea, is an area of , square miles made out of material contributed by upper egypt, and built by the river. layer upon layer, it is constantly forming, but most rapidly during the season of floods. coming closer home, let us look at the map of the mississippi valley. begin as far north as st. louis. for the rest of its course the mississippi river flows through a widening plain of swamp land, flooded in rainy seasons. through this swampy flood plain the river meanders; its current, heavily loaded with sediment, swings from one side to the other of the channel, building up here, wearing away there, and straightening its course when the curves become so sharp that their sides meet. then the current breaks through the thin wall, and a bayou of still water is left behind. below baton rouge the mississippi breaks into many mouths, that spread and carry the water of the great river into the gulf of mexico. the nile delta is triangular, like delta, [greek: d], the fourth letter of the greek alphabet; but the mississippi's delta is very irregular. the main mouth of the river flows fifty miles out into the gulf between mud-banks, narrow and low. at the tip it branches into several streams. from the mouth of the ohio to the gulf, the mississippi flood plain covers , square miles. over this area, sediment to an average depth of fifty feet has been laid down. in earlier times the river flooded this whole area, when freshets swelled its tributaries in the spring. the flood plain then became a sea, in the middle of which the river's current flowed swiftly. the slow-flowing water on each side of the main current let go of its burden of sediment and formed a double ridge. between these two natural walls the main river flowed. when its level fell, two side streams, running parallel with the main river drained the flood plains on each side into the main tributaries to right and left. these natural walls deposited when the river was in flood are called _levees_. each heavy flood builds them higher, and the bed of the stream rises by deposits of sediment. so it happens that the level of the river bed is higher than the level of its flood plain. this is an interesting fact in geology. but the people who have taken possession of the rich flood plain of the mississippi river, who have built their homes there, drained and cultivated the land, and built cities and towns on the areas reclaimed from swamps, recognize the elevation of the river bed as the greatest danger that threatens them. suppose a flood should come. even if it does not overflow the levees, it may break through the natural banks and thus overflow the cities and the farm lands to left and right. instead of living in constant fear of such a calamity, the people of the mississippi flood plain have sought safety by making artificial levees, to make floods impossible. these are built upon the natural levees. as the river bed rises by the deposit of mud, the levees are built higher to contain the rising waters. no longer does the rich soil of the mississippi flood plain receive layers of sediment from the river's overflow. the river very rarely breaks through a levee. the united states government has spent great sums in walling in the river, and each state along its banks does its share toward paying for this self-protection. by means of _jetties_ the river's current is directed into a straightened course, and its power is expended upon the work of deepening its own channel and carrying its sediment to the gulf. much as the river has been forced to do in cleaning its own main channel, dredging is needed at various harbours to keep the river deep enough for navigation. the forests of the mountain slopes in colorado are being slaughtered, and the headwaters of the missouri are carrying more and more rocky débris to choke the current of the mississippi. colorado soil is stolen to build land in the vast delta, which is pushing out into the gulf at the rate of six miles in a century--a mile in every sixteen years. the mississippi delta measures , square miles. with the continued denuding of mountain slopes, we shall expect the rate of delta growth to be greatly increased, until reforesting checks the destructive work of wind and water. the making of mountains the gradual thickening and shrinking of the earth's crust as it cools have made the wrinkles we call mountain systems. through millions of years the globe has been giving off heat to the cold sky spaces through which it swings in its orbit around the sun. the cooling caused the contraction of the outer layer to fit the shrinking of the mass. when a plump peach dries on its pit, the skin wrinkles down to fit the dried flesh. the fruit shrinks by loss of water, just as the face of an old person shrinks by loss of fat. the skin becomes wrinkled in both cases. the weakest places in the earth's crust were the places to crumple, because they could not resist the lateral pressure that was exerted by the shrinking process. along the shores of the ancient seas the rivers piled great burdens of sediment. this caused the thin crust to sink and to become a basin alongside of a ridge. the wearing away of the land in certain places lightened and weakened the crust at these places, so that it bent upward in a ridge. perhaps the first wrinkles were not very high and deep. the gradual cooling must have exerted continued pressure, and the wrinkles have become larger. it is not likely that new wrinkles would be formed as long as the old ones would crumple and draw up into narrower, steeper slopes, in response to the lateral crushing. we can imagine those first mountains rising as folds under the sea. gradually their bases were narrowed, and their crests lifted out of the water. they rose as long, narrow islands, and grew in size as time went on. why is the trend of the great mountain systems almost always north and south? study the map of the continents and see how few cross ranges are shown, and how short they are, compared with the others. the molten globe bulged at its equator, as it rotated on its axis. the moon added its strong pulling force to make it bulge still more. as the crust thickened, it became less responsive to the two forces that caused it to bulge. the shrinkage was greatest where the globe had been most pulled out of shape. the rate of the earth's rotation is believed to have diminished. every change tended to let the earth draw in its (imaginary) belt, a notch at a time. the forces of contraction acted along the line of the equator, and formed folds running toward the poles. in this early time the great mountain systems were born, and they grew in size gradually, from small beginnings. these mountains of upheaval, made by the bending of the earth's crust, and the formation of alternating ridges and depressed valleys, are many. the earth is old and much wrinkled. other mountains have been formed by forces quite different. volcanic mountains have been far more numerous in ages gone than they are now. mt. hood and mt. rainier are peaks built up by the materials thrown out of the craters of volcanoes dead these thousands of years. vesuvius is at present showing us how volcanic mountains are made. each eruption builds larger the cone--that is, the chimney through which the molten rocks, the ashes, and the steam are ejected. side craters may open, the main cone be broken and its form changed, but the mass of lava and stones and ashes grows with each eruption. the mountain grows by the additions it receives. Ætna is a mountain built of lava. a third mountain system grew, not by addition, but by subtraction. the catskills illustrate this type. this group of mountains is the remnant of a table-land made of level layers of red sandstone. the rest of the high plain has been cut down and carried away, leaving these picturesque hills, the survival of which is as much a mystery as the disappearance of the balance of the plateau of which they were once a part. the fold that forms a typical mountain ridge has a cone of granite, the original rock foundation of the earth, and on this are layers of stratified rock, ancient deposits of sediment carried to the sea by streams. when exposed to wind and rain, the ridge is gradually worn down. in some places the water cuts away the soft rock and forms a stream-bed, that cuts deeper and deeper, using the rock fragments as its tools. often the layers of aqueous rocks are cut through, and the granite exposed. sometimes the hardest stratified rock-beds resist the water and the wind and are left as a series of ridges along the sides of the main range. the crumpling forces may crack the ridge open for its whole length, and one side of the chasm may slip down and the other go up. the result is a sheer wall of exposed rock strata, layers of which correspond with those that lie far below the top of the portion that slid down in the great upheaval and subsidence that parted them. these slips are known as _faults_. the lava flood of the northwest we know little about the substance that occupies the four thousand miles of distance between the surface and the centre of our earth. we know that the terrible weight borne by the central mass compresses it, so that the interior must grow denser as the core is approached. scientists have weighed the earth, and tell us that the crust is lighter than the rest. the supposition is that there is a great deal of iron in the interior, and possibly precious metals, too. our deepest wells and mines go down about a mile, then digging stops, on account of the excessive heat. but the crumpling of the crust, and the wearing away of the folded strata by wind and running water, have laid bare rocks several miles in thickness on the slopes of mountains, and exposed the underlying granite, on which the first sedimentary rocks were deposited. on this granite lie stratified rocks, which are crystalline in texture. these are the beds, sometimes miles in depth, called _metamorphic_ rocks, formed by water, then transformed by heat. the wearing away of rocks by wind and water has furnished the materials out of which the aqueous rocks have been made. layers upon layers of sandstone, shales, limestone, and the like, are exposed when a river cuts a canyon through a plateau. the layered deposits of débris at the mouth of the river make new aqueous rocks out of old. every sandy beach is sandstone in the making. this work is never ended. in the early days the earth's crust often gaped open in a mighty crater and let a flood of lava overspread the surface. the ocean floor often received this flood of melted rock. in many places the same chimney opened again and again, each time spreading a new layer of lava on top of the old, so that the surface has several lava sheets overlying the aqueous strata. if the hardened lava sheet proved a barrier to the rising tide of molten lava in the chimney it was often forced out in sheets between the layers of aqueous rocks. wherever the heated material came into contact with aqueous rocks it transformed them, for a foot or more, into crystalline, metamorphic rocks. a chimney of lava is called a _dike_. in mountainous countries dikes are common. sometimes small, they may also be hundreds of feet across, often standing high above the softer strata, which rains have worn away. dikes often look like ruined walls, and may be traced for miles where they have been overturned in the mountain-making process. the great lava flood of the northwest happened when the coast range was born. along the border of the pacific ocean vast sedimentary deposits had accumulated during the cretaceous and tertiary periods. then the mighty upheaval came, the mountain ridge rose at the end of the miocene epoch and stretched itself for hundreds of miles through the region which is now the coast of california and oregon. great fissures opened in the folded crust, and floods of lava overspread an area of , square miles. a dozen dead craters show to-day where those immense volcanic chimneys were. the depth of the lava-beds is well shown where the columbia river has worn its channel through. walls of lava three thousand feet in thickness rise on each side of the river. they are made of columns of basalt, fitted together, like cells of a honeycomb, and jointed, forming stone blocks laid one upon another. the lava shrinks on cooling and forms prisms. in ireland, the giants' causeway is a famous example of basaltic formation. in oregon, the walls of the des chutes river show thirty lava layers, each made of vertical basalt columns. the palisades of the hudson, mt. tom, and mt. holyoke are examples on the eastern side of the continent of basaltic rocks made by lava floods. northern california, northwestern nevada, and large part of idaho, montana, oregon, and washington are included in the basin filled with lava at the time of the great overflow, which extended far into british columbia. it is probable that certain chimneys continued to discharge until comparatively recent times. mt. rainier, mt. shasta, and mt. hood are among dead volcanoes. quite a different history has the great deccan lava-field of india, which covers a larger area than the basin of our northwest, and is in places more than a mile in depth. it has no volcanoes, nor signs of any ever having existed. the floods alone overspread the region, which shows no puny "follow-up system" of scattered craters, intermittently in eruption. the first living things strange days and nights those must have been on the earth when the great sea was still too hot for living things to exist in it. the land above the water-line was bare rocks. these were rapidly being crumbled by the action of the air, which was not the mild, pleasant air we know, but was full of destructive gases, breathed out through cracks in the thin crust of the earth from the heated mass below. if you stand on the edge of a lava lake, like one of those on the islands of the hawaiian group, the stifling fumes that rise might make you feel as if you were back at the beginning of the earth's history, when the solid crust was just a thin film on an unstable sea of molten rock, and this volcano but one of the vast number of openings by which the boiling lava and the condensed gases found their way to the surface. then the rivers ran black with the waste of the rocky earth they furrowed, and there was no vegetation to soften the bleakness of the landscape. the beginnings of life on the earth are a mystery. nobody can guess the riddle. the earliest rocks were subjected to great heat. it is not possible that life could have existed in the heated ocean or on the land. gradually the shores of the seas became filled up with sediment washed down by the rivers. layer on layer of this sediment accumulated, and it was crumpled by pressure, and changed by heat, so that if any plants or animals had lived along those old shores their remains would have been utterly destroyed. rocks that lie in layers on top of these oldest, fire-scarred foundations of the earth show the first faint traces of living things. limestone and beds of iron ore are signs of the presence of life. the first animals and plants lived in the ancient seas. from the traces that are left, we judge that the earliest life forms were of the simplest kind, like some plants and animals that swim in a drop of water. have you ever seen a drop of pond water under a compound microscope? it is a wonder world you look into, and you forget all the world besides. you are one of the wonderful higher animals, the highest on the earth. you focus on a shapeless creature that moves about and feels and breathes, but hasn't any eyes or mouth or stomach--in fact, it is the lowest form of animal life, and one of the smallest. it is but one of many animal forms, all simple in structure, but able to feed and grow and reproduce their kind. gaze out of the window on the garden, now. the flowering plants, the green grass, and the trees are among the highest forms of plants. in the drop of water under the microscope tiny specks of green are floating. they belong to the lowest order of plants. among the plant and the animal forms that have been studied and named, are a few living things the places of which in the scale are not agreed upon. some say they are animals; some believe they are plants. they are like both in some respects. it is probable that the first living things were like these confusing, minute things--not distinctly plants or animals, but the parent forms from which, later on, both plants and animals sprang. the lowest forms of life, plant and animal, live in water to-day. they are tiny and their bodies are made of a soft substance like the white of an egg. if these are at all like the living creatures that swarmed in the early seas, no wonder they left no traces in the rocks of the early part of the age when life is first recorded by fossils. soft-bodied creatures never do. some of the animals and the plants in the drop of water under the microscope have body walls of definite shapes, made of lime, or of a glassy substance called silica. when they die, these "skeletons" lie at the bottom of the water, and do not decay, as the living part of the body does, because they are mineral. gradually a number of these shells, or hard skeletons, accumulate. in a glass of pond water they are found at the bottom, amongst the sediment. in a pond how many thousands of these creatures must live and their shells fall to the bottom at last, buried in the mud! so it is easy to understand why the first creatures on earth left no trace. the first real fossils found in the rocks are the hard shells or skeletons of the first plants and animals that had hard parts. an ancient beach at ebb tide when the tide is out, the rocks on the maine coast have plenty of living creatures to prove this northern shore inhabited. starfishes lurk in the hollows, and the tent-shaped shells of the little periwinkle encrust the wet rocks. mussels cling to the rocks in clumps, fastened to each other by their ropes of coarse black hair. the furry coating of sea mosses that encrust the rocks is a hiding-place for many kinds of living things, some soft-bodied, some protected by shells. the shallow water is the home of plants and animals of many different kinds. as proof of this one finds dead shells and fragments of seaweeds strewn on the shore after a storm. along the outer shores of the cape cod peninsula and down the jersey coast, the sober colouring of the shells of the north gives way to a brighter colour scheme. in the warmer waters, life becomes gayer, if we may judge by the rich tints that ornament the shells. the kinds of living creatures change. they are larger and more abundant. the seaweeds are more varied and more luxuriant in growth. when we reach the shores of the west indian islands and the keys of florida the greatest abundance and variety of living forms are found. the submerged rocks blossom with flower-like sea anemones of every colour. corals, branching like trees and bushes on the sea floor, form groves under water. among them brilliant-hued fishes swim, and highly ornamented shells glide, as people know who have gazed through the glass bottoms of the boats built especially to show visitors the wonderful sea gardens at nassau, bahama islands, and at santa catalina island, southern california. on every beach the skeletons of animals which die help to build up the land; though the process is not so rapid in the north as on the shores that approach the tropics. the coast of florida has a rim of island reefs around it built out of coral limestone. indeed, the peninsula was built by coral polyps. houses in st. augustine are built of coquina rock, which is simply a mass of broken shells held together by a lime cement. every sea beach is packed with shells and other remnants of animals and plants that live in the shallow waters. deeper and deeper year by year the sand buries these skeletons, and many of them are preserved for all time. thus what is sandy beach to-day may, a few million years from now, be uncovered as a ledge of sandstone with the prints of waves distinctly shown, and fossil shells of molluscs, skeletons of fishes, and branches of seaweed--all of them different from those then growing upon the earth. in the neighbourhood of cincinnati there have been uncovered banks of stone accumulated along the border of an ancient sea. from the sides of granite highlands streams brought down the sand built into these oldest sandstone rocks. the fine mud which now appears as beds of slate was the decay of feldspar and hornblende in the same granite. limestone beds are full of the fossil shells of creatures that lived in the shallow seas. their skeletons, accumulating on the bottom, formed deep layers of limestone mud. these rocks preserve, by the fossils they contain, a great variety of shellfish which had limy skeletons. the sea fairly swarmed along its shallow margin with these creatures. we might not recognize many of the shells and other curious fossils we find in the rock uncovered by the workmen who are cutting a railroad embankment. they are not exactly like the living forms that grow along our beaches to-day, but they are enough like them for us to know that they lived along the seashore, and if we had time to examine all the rocks of this kind preserved in a museum we should decide that seashore life was quite as abundant then as it is now. the pressed specimens of plants of those earliest seashores are mere imprints showing that they were pulpy and therefore gradually decayed. only their shape is recorded by dark stains made by each branching part. the decay of the vegetable tissue painted the outline on the rock which when split apart shows us what those ancient seaweeds looked like. they belonged to the group of plants we call kelp, or tangle, which are still common enough in the sea, though the forms we now have are not exactly like the old ones. seaweeds belong to the very lowest forms of plants. [illustration: crinoid from indiana] [illustration: _by permission of the american museum of natural history_ ammonite from jurassic of england] [illustration: _by permission of the american museum of natural history_ fossil corals coquina, hippurite limestone] the limestones are full of fossils of corals. indeed, there must have been reefs like those that skirt florida to-day built by these lime-building polyps. their forms are so well preserved in the rocks that it is possible to know just how they looked when they grew in the shallows. one very common kind is called a cup coral, because the polyp formed a skeleton shaped like a cup. the body wall surrounded the skeleton, and the arms or tentacles rose from the centre of the funnel-like depression in the top. little cups budded off from their parents, but remained attached, and at length the skeletons of all formed great masses of limy rock. some cup corals grew in a solid mass, the new generation forming an outer layer, thus burying the parent cups. a second type of corals in these oldest limestones is the honeycomb group. the colonies of polyps lived in tubes which lengthened gradually, forming compact, limy cylinders like organ pipes, fitted close together. the living generation always inhabited the upper chambers of the tubes. a third type is the chain coral, made of tubes joined in rows, single file like pickets of a fence. but these walls bend into curious patterns, so that the cross-section of a mass of them looks like a complex pattern of crochet-work, the irregular spaces fenced with chain stitches. each open link is a pit in which a polyp lived. among the corals are sprays of a fine feathery growth embedded in the limestone. fine, straight, splinter-like branches are saw-toothed on one or both edges. these limy fossils might not be seen at all, were they not bedded in shales, which are very fine-grained. here again are the skeletons of animals. each notch on each thread-like branch was the home of a tiny animal, not unlike a sea anemone and a coral polyp. to believe this story it is necessary only to pick up a bit of dead shell or floating driftwood on which a feathery growth is found. these plumes, like "sea mosses," as they are called, are not plants at all, but colonies of polyps. each one lived in a tiny pit, and these pits range one above the other, so as to look like notches on the thread-like divisions of the stem. put a piece of this so-called "sea moss" in a glass of sea water, and in a few moments of quiet you will see, by the use of a magnifying glass, the spreading arms of the polyp thrust out of each pit. the ancient seas swarmed with these living hydrozoans, and their remains are found preserved as fossils in the shales which once were beds of soft mud. the hard shells of sea urchins and starfishes are made of lime. in the ancient seas, starfishes were rare and sea urchins did not exist, but all over the sea bottom grew creatures called crinoids, the soft parts of which were enclosed in limy protective cases and attached to rocks on the sea bottom by means of jointed stems. no fossils are more plentiful in the early limestones than these wonderful "stone lilies." indeed, the crinoidal limestone seemed to be built of the skeletons of these animals. the lily-like body was flung open, as a lily opens its calyx, when the creature was feeding. but any alarm caused the tentacles to be drawn in, and the petal-like divisions of the body wall to close tightly together, till that wall looked like an unopened bud. on the bottom of the atlantic, near the bahama islands, these stone lilies are still found growing. their jointed stems and body parts are as graceful in form and motion as any lily. the creature's mouth is in the centre of the flower-like top, and it feeds like the sea urchin, on particles obtained in the sea water. the old limestones contain great quantities of "lamp shells," which are old-fashioned bivalves. their shells remind us of our bivalve clams and scallops, but the internal parts were very different. the gills of clams and oysters are soft parts. inside of the lamp shells are coiled, bony arms, supporting the fringed gills. it is fortunate for us that a few lamp shells still live in the seas. by studying the soft parts of these living remnants of a very old race we can know the secrets of the lives of those ancient lamp shells, the soft parts of which were all washed away, and the fossil shells of which are preserved. gradually the lamp shells died out, and the modern bivalves have come to take their places. just so, the ancient crinoids are now almost extinct; the sea urchins and the starfishes have succeeded them. the chambered nautilus has its shell divided by partitions and it lives in the outer chamber, a many-tentacled creature, that is a close relative of the soft-bodied squid. in the ancient seas the same family was represented by huge creatures the shells of which were chambered, but not coiled. their abundance and great size are proved by the rocks in which their fossils are preserved. some of them must have been the rulers of the sea, as sharks and whales are to-day. fossil specimens have been found more than fifteen feet long and ten inches in diameter in the ancient rocks of some of the western states. it is possible to read from the lowest rock formations upward, the rise of these sea giants and their gradual decline. certain strata of limestone contain the last relics of this race, after which they became extinct. as the straight-chambered forms diminished, great coiled forms became more abundant, but all died out. one of the most abundant fossil animals in ancient rocks is called a trilobite. its body is divided by two grooves into three parts, a central ridge extending the whole length of the body and two side ridges. the front portion of the shell formed the head shield, and behind the main body part was a little tail shield. the skeleton was formed of many movable jointed plates, and the creature had eyes set in the head shield just as the king crab's are set. jointed legs in pairs fringed each side of the body. each leg had two branches, one for walking, the other for swimming. a pair of feelers rose from the head. the body could be rolled into a ball when danger threatened, by bringing head and tail together. these remarkable, extinct trilobites were the first crustaceans. their nearest living relative to-day is the horseshoe crab. the fresh-water crayfish and the lobster are more distant relatives: so are the shrimps and the prawns. no such abundance of these creatures exists to-day as existed when the trilobites thronged the shallows. so well preserved are these skeletons that, although there are no living trilobites for comparison, it is possible to find out from the fossil enough about their structure to know how they fed and lived their lives along with the straight-horns which were the scavengers of those early seas and the terror of smaller creatures. the trilobites throve, and, dying, left their record in the rocks; then disappeared entirely. we find their fossils in a great variety of forms, shapes, and sizes. the smallest is but a fraction of an inch long, the largest twenty inches long. the ancient rocks, in which these lower forms of life have left their fossils, are known as the silurian system. the time in which these rocks were accumulating under the seas covers a vast period. we call it the age of invertebrates, because these soft-bodied, hard-shelled animals, the crinoids, the molluscs, and the trilobites, with bony external skeletons and no backbones, were the most abundant. they overshadowed all other forms of life. the rocks of this wonderful series were formed on the shores of a great inland sea that covered the central portion of north america. in the ages that followed, these rocks were covered deeply with later sediments. but the upheavals of the crust have broken open and erosion has uncovered these strata in different regions. geologists have found written there, page upon page, the record of life as it existed in the early seas. the lime rocks "hard" water and "soft" water are very different. the rain that falls and fills our cisterns is not softer or more delightful to use than the well water in some favoured regions. in it, soap makes beautiful, creamy suds, and it is a real pleasure to put one's hands into it. but in hard water soap seems to curdle, and some softening agent like borax has to be added or the water will chap the hands. there is little satisfaction in using water of this kind for any purpose. hard water was as soft as any when it fell from the sky; but the rain water trickled into the ground and passed through rocks containing lime. some of this mineral was absorbed, for lime is readily soluble in water. clear though it may be, water that has lime in it has quite a different feeling from rain water. blow the breath into a basin of hard water, and a milky appearance will be noted. the carbonic acid gas exhaled from the lungs unites with the invisible lime, causing it to become visible particles of carbonate of lime, which fall to the bottom of the basin. nearly all well water is hard. so is the water of lakes and rivers and the ocean, for limestone is one of the most widely distributed rocks in the surface of the earth. rain water makes its way into the earth's crust, absorbs mineral substances, and collects in springs which feed brooks and rivers and lakes. wells are holes in the ground which bore into water-soaked strata of sand. we gain something from the lime dissolved in hard water, for it is an essential part of our food. we must drink a certain amount of water each day to keep the body in perfect health. the lime in this water goes chiefly to the building of our bones. plant roots take up lime in the water that mounts as sap through the plant bodies. we get some of the lime we need in vegetable foods we eat. all of the kingdom of vertebrate animals, from the lowest forms to the highest, all of the shell-bearing animals of sea and land, require lime. many of the lower creatures especially these in the sea, such as corals and their near relatives, encase themselves in body walls of lime. they absorb the lime from the sea water, and deposit it as unconsciously as we build the bony framework of our bodies. all the bone and shell-bearing creatures that die on the earth and in the sea restore to the land and to the water the lime taken by the creatures while they lived. carbonic acid gas in the water greatly hastens the dissolving of dead shells. carbonic acid gas, whether free in the air, or absorbed by percolating water, hastens the dissolving of skeletons of creatures that die upon land. then the raw materials are built again into lime rocks underground. the lime rocks are the most important group in the list of rocks that form the crust of the earth. they are made of the elements calcium, carbon, and oxygen, yet the different members of this calcite group differ widely in composition and appearance. so do oyster shells and beef bones, though both contain quantities of carbonate of lime. calcite is a soft mineral, light in weight, sometimes white, but oftener of some other colour. it may be found crystallized or not. whenever a drop of acid touches it, a frothy effervescence occurs. the drop of acid boils up and gives off the pungent odour of carbonic acid gas. the reason that calcite is hard to find in rocks is that percolating water, charged with acids, is constantly stealing it, and carrying it away into the ocean. the rocks that contain it crumble because the limy portions have been dissolved out. some limestones resist the destructive action of water. when they are impregnated with silica they become transformed into marble, which takes a high polish like granite. acids must be strong to make any impression on marble. the thick beds of pure limestone that underlie the surface soil in kentucky and in parts of virginia sometimes measure several hundred feet in thickness, a single stratum often being twenty feet thick. they are all horizontal, for they were formed on sea bottom, and have not been crumpled in later time. the dead bodies of sea creatures contributed their shells and skeletons to the lime deposit on the sea bottom. who can estimate the time it took to form those thick, solid layers of lime rock? the animals were corals, crinoids, and molluscs. little sand and clay show in the lime rock of this period, before the marshes of the carboniferous age took the place of the ancient inland sea of the subcarboniferous period, the sedimentary accumulations of which we are now talking about. the living corals one sees in the shallow water of the florida coast to-day are building land by building up their limy skeletons. the reefs are the dead skeletons of past generations of these tiny living things. they take in lime from the water, and use it as we use lime in building our bones. in each case it is an unconscious process of animal growth--not a "building process" like a mason's building of a wall. many people think that the coral polyp builds in this way. they give it credit for patience in a great undertaking. all the polyp does is to feed on whatever the water supplies that its digestive organs can use. it is like a sea anemone in appearance and in habits of life. it is not at all like an insect. yet it is common to hear people speak of the "coral insect"! do not let any one ever hear you repeat such a mistake. southern florida is made out of coral rock, but thinly covered with soil. it was made by the growth of reef after reef, and it is still growing. the cretaceous period of the earth's eventful history is named for the lime rock which we know as chalk. beds of this recent kind of limestone are found in england and in france, pure white, made of the skeletons of the smallest of lime-consuming creatures, foraminifera. they swarmed in deep water, and so did minute sponge animalcules and plant forms called diatoms that took silica from the water, and formed their hard parts of this glassy substance. the result is seen in the nodules of flint found in the soft, snow-white chalk. did you ever use a piece of chalk that scratched the black-board? the flint did it. have you ever seen the chalk cliffs of dover? when you do see them, notice how they gleam white in the sun. see how the rains have sculptured those cliffs. the prominences left standing out are strengthened by the flint they contain. chalk beds occur in texas and under our great plains; but the principal rocks of the age in america were sandstones and clays. the age of fishes the first animal with a backbone recorded its existence among the fossils found in rocks of the upper silurian strata. it is a fish; but the earliest fossils are very incomplete specimens. we know that these old-fashioned fishes were somewhat like the sturgeons of our rivers. their bodies were encased in bony armour of hard scales, coated with enamel. the bones of the spine were connected by ball and socket joints, and the heads were movable. in these two particulars the fishes resembled reptiles. the modern gar-pike has a number of the same characteristics. another backboned creature of the ancient seas was the ancestral type of the shark family. in some points this old-fashioned shark reminds us of birds and turtles. these early fishes foreshadowed all later vertebrates, not yet on the earth. after them came the amphibians, then the reptiles, then the birds, and latest the mammals. the race of fishes began, no doubt, with forms so soft-boned that no fossil traces are preserved in the rocks. when those with harder bones appeared, the fossil record began, and it tells the story of the passing of the early, unfish-like forms, and the coming of new kinds, great in size and in numbers, that swarmed in the seas, and were tyrants over all other living things. they conquered the giant straight-horns and trilobites, former rulers of the seas. [illustration: _by permission of the american museum of natural history_ a sixteen-foot fossil fish from cretaceous of kansas, with a modern tarpon] [illustration: _by permission of the american museum of natural history_ cañon diablo meteorite from arizona] one of these giant fishes fifteen to twenty feet long, three feet wide, had jaws two feet long, set with blade-like teeth. devonian rocks in ohio have yielded fine fossils of gigantic fishes and sharks. devonian fishes were unlike modern kinds in these particulars, the spinal column extended to the end of the tail, whether the fins were arranged equally or unequally on the sides; the paired side fins look like limbs fringed with fins. every devonian fish of the gar type seems to have had a lung to help out its gill-breathing. in these traits the first fishes were much like the amphibians. they were the parent stock from which branched later the true fishes and the amphibians, as a single trunk parts into two main boughs. the trunk is the connecting link. the sea bottom was still thronged with crinoids, and lamp shells, and cup corals. shells of both clam and snail shapes are plentiful. the chambered straight-horns are fewer and smaller, and coiled forms of this type of shell are found. trilobite forms are smaller, and their numbers decrease. the first land plants appeared during this age. ferns and giant club mosses and cycads grew in swampy ground. this was the beginning of the wonderful fern forests that marked the next age, when coal was formed. the rocks that bear the record of these living things in their fossils, form strata of great thickness that overlie the silurian deposits. there is no break between them. so we understand that the sea changed its shore-line only when the silurian deposits rose to the water-level. the devonian sea was smaller than the silurian. a great tract of devonian deposits occupies the lower half of the state of new york, canada between lakes erie and huron, and the northern portions of indiana and illinois. these older layers of the stratified rock are covered with the deposits of later periods. rivers that cut deep channels reveal the earlier rocks as outcrops along their canyon walk. the record of the age of fishes is, for the most part, still an unopened book. the pages are sealed, waiting for the geologist with his hammer to disclose the mysteries. king coal in this country, and in this age, who can doubt that coal is king? it is one of the few necessities of life. in various sections of the country, layers of coal have been discovered--some near the surface, others deep underground. these are the storehouses of fuel which the coal miners dig out and bring to the surface, and the railroads distribute. from pennsylvania and ohio to alabama stretches the richest coal-basin. illinois and indiana contain another. from iowa southward to texas another broad basin lies. central michigan and nova scotia each has isolated coal-basins. all these have been discovered and mined, for they lie in the oldest part of the country. in the west, coal-beds have been discovered in several states, but many regions have not yet been explored. vast coal-fields, still untouched, have been located in alaska. the government is trying to save this fuel supply for coming generations. many of the richest coal-beds from nova scotia southward dip under the ocean. they have been robbed by the erosive action of waves and running water. glaciers have ground away their substance, and given it to the sea. much that remains intact must be left by miners on account of the difficulties of getting out coal from tilted and contorted strata. as a rule, the first-formed coal is the best. the western coal-fields belong to the period following the carboniferous age. although conditions were favourable to abundant coal formation, western coal is not equal to the older, eastern coal. it is often called _lignite_, a word that designates its immaturity compared with anthracite. coal formed in the triassic period is found in a basin near richmond, virginia. there is an abundance of this coal, but it has been subjected to mountain-making pressure and heat, and is extremely inflammable. the miners are in constant danger on account of coal gas, which becomes explosive when the air of the shaft reaches and mingles with it. this the miner calls "fire damp." north carolina has coal of the same formation, that is also dangerous to mine, and very awkward to reach, on account of the crumpling of the strata. there are beds of coal so pure that very little ash remains after the burning. five per cent, of ash may be reasonably expected in pure coal, unmixed with sedimentary deposits. such coal was formed in that part of the swamp which was not stirred by the inflow of a river. wherever muddy water flowed in among the fallen stems of plants, or sand drifted over the accumulated peat, these deposits remained, to appear later and bother those who attempt to burn the coal. [illustration: eocene fish] [illustration: _by permission of the american museum of natural history_ trilobite from the niagara limestone, upper silurian, of western new york] [illustration: sigillaria, stigmaria and lepidodendron] [illustration: _by permission of the american museum of natural history_ coal fern] you know pure coal, that burns with great heat and leaves but little ashes. you know also the other kind, that ignites with difficulty, burns with little flame, gives out little heat, and dying leaves the furnace full of ashes. you are trying to burn ancient mud that has but a small proportion of coal mixed with it. the miners know good coal from poor, and so do the coal dealers. it is not profitable to mine the impure part of the vein. it costs as much to mine and ship as the best quality, and it brings a much lower price. the deeper beds of coal are better than those formed in comparatively recent time and found lying nearer the surface. in many bogs a layer of embedded root fibres, called peat, is cut into bricks and dried for burning. deeper than peat-beds lie the _lignites_, which are old beds of peat, on the way to become coal. _soft coal_ is older than lignite. it contains thirty to fifty per cent. of volatile matter, and burns readily, with a bright blaze. the richest of this bituminous coal is called _fat_, or _fusing coal_. the bitumen oozes out, and the coal cakes in burning. ordinary soft coal contains less, but still we can see the resinous bitumen frying out of it as it burns. there is more heat and less volatile matter in _steam coal_, so-called because it is the fuel that most quickly forms steam in an engine. _hard coal_ contains but five to ten per cent. of volatile matter. it is slow to ignite and burns with a small blue blaze. from peat to anthracite coal i have named the series which increases gradually in the amount of heat it gives out, and increases and then decreases in its readiness to burn and in the brightness of its flame. anthracite coal has the highest amount of fixed carbon. this is the reason why it makes the best fuel, for fixed carbon is the substance which holds the store of imprisoned sunlight, liberated as heat when the coal burns. tremendous pressure and heat due to shrinking of the earth's crust have crumpled and twisted the strata containing coal in eastern pennsylvania, and thus changed bituminous coal into anthracite. ohio beds, formed at the same time, but undisturbed by heat and pressure, are bituminous yet. the coal-beds of rhode island are anthracite, but the coal is so hard that it will not burn in an open fire. the terrible, mountain-making forces that crumpled these strata and robbed the coal of its volatile matter, left so little of the gas-forming element, that a very special treatment is necessary to make the carbon burn. it is used successfully in furnaces built for the smelting of ores. the last stage in the coal series is a black substance which we know as black lead, or graphite. we write with it when we use a "lead" pencil. this is anthracite coal after all of the volatile matter has been driven out of it. it cannot burn, although it is solid carbon. the beds of graphite have been formed out of coal by the same changes in the earth's crust which have converted soft coal into anthracite. the tremendous pressure that bears on the coal measures has changed a part of the carbon into liquid and gaseous form. lakes of oil have been tapped from which jets of great force have spouted out. such accumulations of oil usually fill porous layers of sandstone and are confined by overlying and underlying beds of impervious clay. gas may be similarly confined until a well is drilled, relieving the pressure, and furnishing abundant or scanty supply of this valuable fuel. western pennsylvania coal-fields have beds of gas and oil. if mountain-making forces had broken the strata, as in eastern pennsylvania, the gas and the oil would have been lost by evaporation. this is what happened in the anthracite coal-belt. how coal was made the broad, rounded dome of a maple tree shades my windows from the intense heat of this august day. the air is hot, and every leaf of the tree's thatched roof is spread to catch the sunlight. the carbon in the air is breathed in through openings on the under side of each leaf. the sap in the leaf pulp uses the carbon in making starch. the sun's heat is absorbed. it is the energy that enables the leaf-green to produce a wonderful chemical change. out of soil water, brought up from the roots, and the carbonic acid gas, taken in from the air, rich, sugary starch is manufactured in the leaf laboratory. this plant food returns in a slow current, feeding the growing cells under the bark, from leaf tip to root tip, throughout the growing tree. the sap builds solid wood. the maple tree has been built out of muddy water and carbon gas. it stands a miracle before our eyes. in its tough wood fibres is locked up all the heat its leaves absorbed from the sun, since the day the maple seed sprouted and the first pair of leaves lifted their palms above the ground. if my maple tree should die, and fall, and lie undisturbed on the ground, it would slowly decay. the carbon of its solid frame would pass back into the air, as gas, and the heat would escape so gradually that i could not notice it at all, unless i thrust my hand into the warm, crumbling mass. if my tree should be cut down to-day and chopped into stove wood, it would keep a fire in my grate for many months. burning destroys wood substance a great deal faster than decay in the open air does, but the processes of rotting and burning are alike in this: each process releases the carbon, and gives it back to the air. it gives back also the sun's heat, stored while the tree was growing. there is left on the ground, and in the ashes on the hearth, only the mineral substance taken up in the water the roots gathered underground. if my tree stood in swampy ground and fell over under a high wind, the water that covered it and saturated its substance would prevent decay. the carbon would not be allowed to escape as a gas to the air; the woody substance would become gradually changed into _peat_. in this form it might remain for thousands of years, and finally be changed into coal. whether it was burned while yet in the condition of peat, or millions of years later, when it was transformed into coal, the heat stored in its substance was liberated by the burning. the carbon and the heat went back to the air. every green plant we see spreads its leaves to the sun. every stick of wood we burn, and every lump of coal, is giving back, in the form of light and heat, the energy that came from sunshine and was captured by the green leaves. how long the wood has held this store of heat we may easily compute, for we can read the age of a tree. but the age of coal we cannot accurately state. the years probably should be counted by millions, instead of thousands. the great inland sea that covered the middle portion of the continent during the silurian and the devonian periods, became shallow by the deposit of vast quantities of sediment. along the lines of the deposits of greatest thickness, a crumpling of the earth's crust lifted the first fold of the alleghany mountains as a great sea wall on the east, and on the western shore another formed the beginning of the ozark mountain system in missouri. an island was lifted out of the sea, forming the elevated ground on which the city of cincinnati now stands. various other ridges and islands divided the ancient sea into much smaller bodies of water. hemmed in by land these shallow sea-basins gradually changed into fresh-water lakes, for they no longer had connection with the ocean, and all the water they received came from rain. after centuries of freshets, and of filling in with the rock débris brought by the streams, they became great marshes, in which grew water-loving plants. generation after generation of these plants died, and their remains, submerged by the water, were converted into peat. in the course of ages this peat became coal. this is the history of the coal measures. there is no guesswork here. the stems of plants do not lose their microscopic structure in all the ages it has taken to transform them to coal. a thin section of coal shows under a magnifier the structure of the stems of the coal-forming plants. moreover, the veins of coal preserve above or below them, in shales that were once deposits of mud, the branching trunks of trees, perfectly fossilized. there are no better proofs of the vegetable origin of coal than the lumps themselves. but they are plain to the naked eye, while the coal tells its story to the man with the microscope. the fossil remains of the plants that flourished when coal was forming are gigantic, compared with plants of the same families now living. we must conclude that the climate was tropical, the air very heavy with moisture, and charged much more heavily than it is now with carbonic acid gas. these conditions produced, in rapid succession, forests of tree ferns and horsetails and giant club mosses. these are the three types of plants out of which the coal was made. they were all rich in resin, which makes the coal burn readily. the ferns had stems as large as tree trunks. some have been found that are eighteen inches in diameter. we know they are ferns, because the leaves are found with their fruits attached to them in the manner of present-day ferns. the stems show the well known scar by which fern leaves are joined. and the wood of these fossil fern stems is tubular in structure, just as the wood of living ferns is to-day. among the ferns which dominated these old marsh forests grew one kind, the scaly leaves of which covered the stems and bore their fruits on the branching tips. these giants, some of them with trunks four feet in diameter, belong to the same group of plants as our creeping club mosses, but in the ancient days they stood up among the other ferns as trees forty or fifty feet high. the giant scouring rushes, or horsetails, had the same general characteristics as the little reed-like plants we know by those names to-day. the highest plants of the coal period were leafy trees with nut-like fruits, that resemble the yew trees of the present. these gigantic trees were the first conifers upon the earth. they foreshadowed the pines and the other cone-bearing evergreens. their leaves were broad and their fruits nut-like. the japanese ginkgo, or maidenhair fern tree, is an old-fashioned conifer somewhat like those first examples of this family. trunks sixty to seventy feet long, crowned with broad leaves and a spike of fruit, have been found lying in the upper layers of the coal-seams, and in sandstone strata that lie between the strata of coal. peculiar circular discs, which the microscope reveals along the sides of the wood fibres of these fossil trees, prove the wood structure to be like that of modern conifers. generation after generation of forests lived and died in the vast spreading swamps of this era. the land sank, and freshets came here and there, drowning out all plant life, and covering the layers of peat with beds of sand or mud. when the water went down, other forests took possession, and a new coal-bed was started. it is plainly seen that flooding often put an end to coal formation. fifteen seams of coal, one above another, is the greatest number that have been found. the veins vary from one inch to forty feet in thickness. these are separated by layers of sandstone or shale, which accumulated as sediment, covering the stumps of dead tree ferns and other growths, and preserving them as fossils to tell the story of those bygone ages as plainly as any other record could have done. fresh-water animals succeeded those of salt water in the swamps that formed the coal measures. overhead, the first insects flitted among the branches of the tree ferns. dragon-flies darted above the surface and dipped in water as they do to-day. spiders, scorpions, and cockroaches, all air-breathing insects, were represented, but none of the higher, nectar-loving insects, like flies and bees and butterflies, were there. flowering plants had not yet appeared on the earth. snakelike amphibians, some fishlike, some lizard-like, and huge crocodilian forms appeared for the first time. these air-breathing swamp-dwellers could not have lived in salt water. fresh-water molluscs and land shells appear for the first time as fossils in the rocks of the coal measures. on the shores of the ocean, the rocks of this period show that trilobites, horseshoe crabs, and fishes still lived in vast numbers, and corals continued to form limestone. the old types of marine animals changed gradually, but the coal measures show strikingly different fossils. these rocks bear the first record of fresh-water and land animals. the most useful metal it is fortunate for us all that, out of the half-dozen so-called useful metals, iron, which is the most useful of them all to the human race, should be also the most plentiful and the cheapest. aluminum is abundant in the common clay and soil under our feet. but separating it is still an expensive process; so that this metal is not commercially so plentiful as iron is, nor is it cheap. all we know of the earth's substance is based on studies of the superficial part of its crust, a mere film compared with the eight thousand miles of its diameter. nobody knows what the core of the earth--the great globe under this surface film--is made of; but we know that it is of heavier material than the surface layer; and geologists believe that iron is an important element in the central mass of the globe. one thing that makes this guess seem reasonable is the great abundance of iron in the earth's crust. another thing is that meteors which fall on the earth out of the sky prove to be chiefly composed of iron. all of their other elements are ones which are found in our own rocks. if we believe that the earth itself is a fragment of the sun, thrown off in a heated condition and cooling as it flew through space, we may consider it a giant meteor, made of the substances we find in the chance meteor that strikes the earth. iron is found, not only in the soil, but in all plant and animal bodies that take their food from the soil. the red colour in fruits and flowers, and in the blood of the higher animals, is a form in which iron is familiar to us. it does more, perhaps, to make the world beautiful than any other mineral element known. but long before these benefits were understood, iron was the backbone of civilization. it is so to-day. iron, transformed by a simple process into steel, sustains the commercial supremacy of the great civilized nations of the world. the railroad train, the steel-armoured battleship, the great bridge, the towering sky-scraper, the keen-edged tool, the delicate mechanism of watches and a thousand other scientific instruments--all these things are possible to-day because iron was discovered and has been put to use. it was probably one of the cave men, poking about in his fire among the rocks, who discovered a lump of molten metal which the heat had separated from the rest of the rocks. he examined this "clinker" after it cooled, and it interested him. it was a new discovery. it may have been he, or possibly his descendants, who learned that this metal could be pounded into other shapes, and freed by pounding from the pebbles and other impurities that clung to it when it cooled. the relics of iron-tipped spears and arrows show the skill and ingenuity of our early ancestors in making use of iron as a means of killing their prey. the earliest remains of this kind have probably been lost because the iron rusted away. man was pretty well along on the road to civilization before he learned where iron could be found in beds, and how it could be purified for his use. we now know that certain very minute plants, which live in quiet water, cause iron brought into that water to be precipitated, and to accumulate in the bottom of these boggy pools. in ancient days these bog deposits of iron often alternated with coal layers. millions of years have passed since these two useful substances were laid down. to-day the coal is dug, along with the bog iron. the coal is burned to melt the iron ore and prepare it for use. it is a fortunate region that produces both coal and iron. bituminous coal is plentiful, and scattered all over the country, while anthracite is scarce. the cheapest iron is made in alabama, which has its ore in rich deposits in hillsides, and coal measures close by, furnishing the raw material for coke. the result is that the region of birmingham has become the centre of great wealth through the development of iron and coal mines. where water flows over limestone rock, and percolates through layers of this very common mineral, it causes the iron, gathered in these rock masses, to be deposited in pockets. all along the appalachian mountains the iron has been gathered in beds which are being mined. these beds of ore are usually mixed with clay and other earthy substances from which the metal can be separated only by melting. the ore is thrown into a furnace where the metal melts and trickles down, leaving behind the non-metallic impurities. it is drawn off and run into moulds, where it cools in the form of "pig" iron. the first fuel used in the making of pig iron from the ore was charcoal. in america the early settlers had no difficulty in finding plenty of wood. indeed, the forests were weeds that had to be cut down and burned to make room for fields of grain. the finding of iron ore always started a small industry in a colony. if there was a blacksmith, or any one else among the small company who understood working in iron, he was put in charge. to make the charcoal, wood was cut and piled closely in a dome-shaped heap, which was tightly covered with sods, except for a small opening near the ground. in this a fire was built, and smothered, but kept going until all the wood within the oven was charred. this fuel burned readily, with an intense heat, and without ashes. sticks of charcoal have the form of the wood, and they are stiff enough to hold up the ore of iron so that it cannot crush out the fire. for a long time american iron was supplied by little smelters, scattered here and there. the workmen beat the melted metal on the forge, freeing it from impurities, and shaping the pure metal into useful articles. sometimes they made it into steel, by a process learned in the old world. the american iron industry, which now is one of the greatest in the world, centres in pittsburg, near which great deposits of iron and coal lie close together. the making of coke from coal has replaced the burning of charcoal for fuel. when the forests were cut away by lumbermen, the supply of charcoal threatened to give out, and experiments were made in charring coal, which resulted in the successful making of coke, a fuel made from coal by a process similar to the making of charcoal from wood. the story of the making of coke out of hard and soft coal is a long one, for it began as far back as the beginning of the nineteenth century. in the first boat-load of anthracite coal was sent to philadelphia from a little settlement along the lehigh river. a mine had been opened, the owner of which believed that the black, shiny "rocks" would burn. his neighbours laughed at him, for they had tried building fires with them, and concluded that it could not be done. in philadelphia, the owners of some coke furnaces gave the new fuel a trial, in spite of the disgust of the stokers, who thought they were putting out their fires with a pile of stones. after a little, however, the new fuel began to burn with the peculiar pale flame and intense heat that we know so well, and the stokers were convinced that here was a new fuel, with possibilities in it. but it was hard for people to be patient with the slow starting of this hard coal. not until did it come into general favour, following the discovery that if hot air was supplied at the draught, instead of cold, anthracite coal became a perfect fuel. at connellsville, pennsylvania, a vein of coal was discovered which made coke of the very finest quality. around this remarkable centre, coke ovens were built, and iron ore was shipped in, even from the rich beds of the lake superior country. but it was plain to see that connellsville coal would become exhausted; and so experiments in coke-making from other coals were still made. when soft coal burns, a waxy tar oozes out of it, which tends to smother the fire. early experiments with coal in melting iron ore indicated that soft coal was useless as a substitute for charcoal and coke; but later experiments proved that coke of fine quality can be made out of this bituminous soft coal, by drawing off the tar which makes the trouble. new processes were invented by which valuable gas and coal tar are taken out of bituminous coal, leaving, as a residue, coke that is equal in quality to that made from the connellsville coal. fortunes have been made out of the separation of the elements of the once despised soft coal. for the coke and each of its by-products, coal tar and coal gas, are commercial necessities of life. the impurities absorbed by the melting iron ore include carbon, phosphorus, and silicon. carbon is the chief cause of the brittleness of cast iron. the puddling furnace was invented to remove this trouble. the melted ore was stirred on a broad, basin-like hearth, with a long-handled puddling rake. the flames swept over the surface, burning the carbon liberated by the stirring. it was a hard, hot job for the man at the rake, but it produced forge iron, that could be shaped, hot or cold, on the anvil. the next improvement was the process of pressing the hot iron between grooved rollers to rid it of slag and other foreign matters collected in the furnace. the old way was to hammer the metal free from such impurities. this was slow and hard work. iron was an expensive and scarce metal until the hot blast-furnace cheapened the process of smelting the ore. the puddling furnace and the grooved rollers did still more to bring it into general use. the railroads developed with the iron industry. soon they required a metal stronger than iron. steel was far too expensive, though it was just what was needed. efforts were made to find a cheap way to change iron into steel. sir henry bessemer solved the problem by inventing the bessemer converter. it is a great closed retort, which is filled with melted pig iron. a draught admits air, and the carbon is all burned out. then a definite amount of carbon, just the amount required to change iron into steel, is added, by throwing in bars of an alloy of carbon and manganese. the latter gives steel its toughness, and enables it to resist greater heat without crystallizing and thus losing its temper. when the carbon has been put in, the retort is closed. the molten metal absorbs the alloy, and the product is bessemer steel. in fifteen minutes pig iron can be transformed into ingot steel. the invention made possible the use of steel in the construction of bridges, high buildings, and ships. it made this age of the world the age of steel. the age of reptiles two big and interesting reptiles we see in the zoo, the crocodile and its cousin, the alligator. in the everglades of florida both are found. the crocodile of the nile is protected by popular superstition, so it is in better luck than ours. the alligators have been killed off for their skins, and it is only a matter of time till these lumbering creatures will be found only in places where they are protected as the remnants of a vanished race. giant reptiles of other kinds are few upon the earth now. the _boa constrictor_ is the giant among snakes. the great tropical turtles represent an allied group. most of the turtles, lizards, and snakes are small, and in no sense dominant over other creatures. the rocks that lie among the coal measures contain fossils of huge animals that lived in fresh water and on land, the ancestors of our frogs, toads, and salamanders, a group we call amphibians. some of these animals had the form of snakes; some were fishlike, with scaly bodies; others were lizard-like or like huge crocodiles. these were the ancestors of the reptiles, which became the rulers of land and sea during the mesozoic era. the rocks that overlie the coal measures contain fossils of these gigantic animals. strange crocodile-like reptiles, with turtle-like beaks and tusks, but no teeth, left their skeletons in the mud of the shores they frequented. and others had teeth in groups--grinders, tearers, and cutters--like mammals. these had other traits like the old-fashioned, egg-laying mammals, the duck-billed platypus, for example, that is still found in australia. along with the remains of these creatures are found small pouched mammals, of the kangaroo kind, in the rocks of europe and america. these land animals saw squatty cycads, and cone-bearing trees, the ancestors of our evergreens, growing in forests, and marshes covered with luxuriant growths of tree ferns and horsetails, the fallen bodies of which formed the recent coal that is now dug in virginia and north carolina. ammonites, giant sea snails, with chambered shells that reached a yard and more in diameter, and gigantic squids, swam the seas. sea urchins, starfish, and oysters were abundant. insects flitted through the air, but no birds appeared among the trees or beasts in the jungles. over all forms of living creatures reptiles ruled. they were remarkable in size and numbers. there were swimming, running, and flying forms. [illustration: banded sandstone from calico cañon, south dakota] [illustration: _by permission of the american museum of natural history_ opalized wood from utah] [illustration: _by permission of the american museum of natural history_ restoration of a carnivorous dinosaur, allosaurus, from the upper jurassic and lower cretaceous of wyoming. when erect the animal was about feet high] the fish-reptile, _ichthyosaurus_, was a hump-backed creature, thirty to forty feet long, with short neck, very large head, and long jaw, set with hundreds of pointed teeth. its eye sockets were a foot across. the four short limbs were strong paddles, used for swimming. the long, slender tail ended in a flat fin. perfect skeletons of this creature have been found. its rival in the sea was the lizard-like _plesiosaurus_, the small head of which was mounted on a long neck. the tail was short, but the paddles were long and powerful. no doubt this agile creature held its own, though somewhat smaller than the more massively built ichthyosaurus. the land reptiles called _dinosaurs_ were the largest creatures that have ever walked the earth. in the american museum of natural history, in new york, the mounted skeleton of the giant dinosaur fairly takes one's breath away. it is sixty-six feet long, and correspondingly large in every part, except its head. this massive creature was remarkably short of brains. the strangest thing about the land reptiles is the fact that certain of them walked on their hind legs, like birds, and made three-toed tracks in the mud. indeed, these fossil tracks, found in slate, were called bird tracks, until the bones of the reptile skeleton with the bird-like foot were discovered. certain long grooves in the slate, hitherto unexplained, were made by the long tail that dragged in the mud. when the mud dried, and was later covered with sediment of another kind, these prints were preserved, and when the bed of rock was discovered by quarrymen, the two kinds split apart, showing the record of the stroll of a giant along the river bank in bygone days. the flying reptiles were still more bird-like in structure, though gigantic in size. imagine the appearance of a great lizard with bat-like, webbed wings and bat-like, toothed jaws! the first feathered fossil bird was discovered in the limestone rock of bavaria. it was a wonderfully preserved fossil, showing the feathers perfectly. three fingers of each "hand" were free and clawed, so that the creature could seize its prey, and yet use its feathered wings in flight. the small head had jaws set with socketed teeth, like a reptile's, and the long, lizard tail of twenty-one bones had a pair of side feathers at each joint. this _archeopteryx_ is the reptilian ancestor of birds. during this age of the world, one branch of the reptile group established the family line of birds. the bird-like reptiles are the connecting link between the two races. how much both birds and reptiles have changed from that ancient type, their common ancestor! i have mentioned but a few of the types of animals that make the reptilian age the wonder of all time. one after another skeletons are unearthed and new species are found. the connecticut river valley, with its red sandstones and shales of the mesozoic era, is famous among geologists, because it preserves the tracks of reptiles, insects, and crustaceans. these signs tell much of the life that existed when these flakes of stone were sandy and muddy stretches not many bones have been found, however. the thickness of these rocks is between one and two miles. the time required to accumulate so much sediment must have been very great. [illustration: _by permission of the american museum of natural history_ model of a three-horned dinosaur, _triceratops_, from cretaceous of montana. animal in life about feet long] [illustration: _by permission of the american museum of natural history_ mounting the forelegs of _brontosaurus_, the aquatic dinosaur] it is not clear just what caused the race of giant reptiles to decline and pass away. the climate did not materially change. perhaps races grow old, and ripe for death, after living long on the earth. it seems as if their time was up; and the clumsy giants abdicated their reign, leaving dominion over the sea, the air, and the land to those animals adapted to take the places they were obliged to vacate. the age of mammals the warm-blooded birds and mammals followed the reptiles. this does not mean that all reptiles died, after having ruled the earth for thousands of years. it means that changes in climate and other life conditions were unfavourable to the giants of the cold-blooded races, and gradually they passed away. they are represented now on the earth by lesser reptiles, which live comfortably with the wild creatures of other tribes, but which in no sense rule in the brute creation. they live rather a lurking, cautious life, and have to hide from enemies, except a few more able kinds, provided with means of defense. there were mammals on the earth in the days of reptilian supremacy, but they were small in size and numbers, and had to avoid any open conflict with the giant reptiles, or be worsted in a fight. now the time came when the ruling power changed hands. the mammals had their turn at ruling the lower animals. it was the beginning of things as they are to-day, for mammals still rule. but many millions of years have probably stood between the age when this group of animals first began to swarm over the earth, and the time when man came to be ruler over all created things. among the reptiles of the period when the sea, the land, and the air were swarming with these great creatures were certain kinds that had traits of mammals. others were bird-like. from these reptilian ancestors birds and mammals have sprung. no one doubts this. the fossils prove it, step by step. yet the rocks surprise the geologist with the suddenness with which many new kinds of mammals appeared on the earth. possibly the rocks containing the bones of so many kinds were fortunately located. the spots may have been morasses where migrating mammals were overwhelmed while passing. possibly conditions favored the rapid development of new kinds, and the multiplication of their numbers. warm, moist climate furnished abundant succulent plant food for the herbivors, and these in turn furnished prey for the carnivors. the coal formed during the tertiary period gives added proof that the plant life was luxuriant. the kinds of trees that grew far north of our present warm zones have left in the rocks evidence in the form of perfect leaves and cones and other fruits. for instance, magnolias grew in greenland, and palm trees in dakota. the temperature of greenland was thirty degrees warmer than it is now. our northern states lie in a belt that must have had a climate much like that of florida now. europe was correspondingly mild. a special chapter tells of the gradual development of the horse. one hundred different kinds of mammals have been found in the eocene rocks, many of which have representative species at the same time in europe and america. the rocks of asia probably have similar records. the eocene rocks, lowest of the tertiary strata, contain remains of animals the families of which are now extinct. next overlying the eocene, the miocene rocks have fossils of animals belonging to modern families--rhinoceroses, camels, deer, dogs, cats, horses--but the genera of which are now extinct. the pliocene strata (above the miocene) contains fossils of animals so closely related to the wild animals now on the earth as to belong to the same genera. they differ from modern kinds only in the species, as the red squirrel is a different species from the gray. so the record in the rocks shows a gradual approach of the mammals to the kinds we know, a gradual passing of the mighty forms that ruled by size and strength, and the coming of forms with greater intelligence, adapted to the change to a colder climate. it sometimes happens that a farmer, digging a well on the prairie, strikes the skeleton of a monster mammal, called the _mastodon_. this very thing happened on a neighbour's farm when i was a girl, in iowa. everybody was excited. the owner of the land dug out every bone, careful that the whole skeleton be found. as he expected, the director of a museum was glad to pay a high price for the bones. [illustration: _by permission of the american museum of natural history_ restoration of an aquatic dinosaur, _brontosaurus excelsus_, from the upper jurassic and lower cretaceous of wyoming. the animal in life was over feet long] [illustration: _by permission of the american museum of natural history_ restoration of the small carnivorous dinosaur, _ornitholestes hermanui_, catching a primitive bird _archæopteryx_. upper jurassic and lower cretaceous] the mastodon was about the size of an elephant, with massive limbs, and large, heavy head that bore two stout, up-curved tusks of ivory. the creature moved in herds like the buffalo from swamp to swamp; and old age coming on, the individual, unable to keep up with the herd, sank to his death in the boggy ground. the peat accumulated over his bones, undisturbed until thousands of years elapse, and the chance digging of a well discovers his skeleton. frozen in the ice of northern siberia, near the mouths of rivers, a number of mammoths have been found. these are creatures of the elephant family, and belonging to the extinct race that lived in the quaternary period, just succeeding the tertiary. the ice overtook the specimens, and they have been in cold storage ever since. for this reason, both flesh and bones are preserved, a rare thing to happen, and rarer still to be seen by a scientist. the ignorant natives made a business of watching the ice masses at the river mouth for dark spots that showed where a mammoth was encased in the ice. if an iceberg broke off near such a place, the sun might thaw the ice front of the glacier, until the hairy monster could at length be reached. his long hair served for many uses, and the wool that grew under the hair was used as a protection from the arctic winter. the frozen flesh was eaten; the bones carved into useful tools; but the chief value of the find was in the great tusks of ivory, that curved forward and pointed over the huge shoulders. it was worth a fortune to get a pair and sell them to a buyer from st. petersburg. one of the finest museum specimens of the mammoth was secured by buying the tusks of the dealer, and by his aid tracing the location of the carcass, which was found still intact, except that dogs had eaten away part of one foreleg, bone and all. from this carefully preserved specimen, models have been made, exactly copying the shape and the size of the animal, its skin, hair, and other details. the sabre-toothed tiger, the sharp tusks of which, six to eight inches long, made it a far more ferocious beast than any modern tiger of tropical jungles, was a quaternary inhabitant of europe and america. so was a smaller tiger, and a lion. the irish elk, which stood eleven feet high, with antlers that spread ten feet apart at the tips, was monarch in the deer family, which had several different species on both continents. wild horses and wild cattle, one or two of great size, roamed the woods, while rhinos and the hippopotamus kept near the water-courses. hyenas skulked in the shadows, and acted as scavengers where the great beasts of prey had feasted. sloths and cuirassed animals, like giant armadillos, lived in america. among bears was one, the cave bear, larger than the grizzly. true monkeys climbed the trees. flamingo, parrots, and tall secretary birds followed the giant _gastornis_, the ancestor of wading birds and ostriches, which stood ten feet high, but had wings as small and useless as the auk of later times. with the entrance of the modern types of trees, came other flowering plants, and with them the insects that live on the nectar of flowers. through a long line of primitive forms, now extinct, flowering plants and their insect friends conform to modern types. the record is written in the great stone book. the age of mammals in america and europe ended with the gradual rise of the continental areas, and a fall of temperature that ushered in the ice age. with the death of tropical vegetation, the giant mammals passed away. the horse and his ancestors every city has a horse market, where you may look over hundreds of animals and select one of any colour, size, or kind. the least in size and weight is the shetland pony, which one man buys for his children to drive or ride. another man wants a long-legged, deep-chested hunter. another wants heavy draught-horses, with legs like great pillars under them, and thick, muscular necks--horses weighing nearly a ton apiece and able to draw the heaviest trucks. what a contrast between these slow but powerful animals and the graceful, prancing racer with legs like pipe-stems--fleet and agile, but not strong enough to draw a heavy load! all these different breeds of horses have been developed since man succeeded in capturing the wild horse and making it help him. man himself was still a savage, and he had to fight with wild beasts, as if he were one of them, until he discovered that he could conquer them by some power higher than physical strength. from this point on, human intelligence has been the power that rules the lower animals. its gradual development is the story of the advance of civilization on the earth. through unknown thousands of years it has gone on, and it is not yet finished. [illustration: _by permission of the american museum of natural history_ restoration of a siberian mammoth, _elephas primogenius_, pursued by men of the old stone age of europe. late pleistocene epoch] [illustration: _by permission of the american museum of natural history_ restoration of a small four-toed ancestor of the horse family, _eohippus venticolus_. lower eocene of wyoming] just when and where and how our savage ancestors succeeded in taming the wild horse of the plains and the forests of europe or asia is unknown. man first made friends with the wild sheep, which were probably more docile than wild oxen and horses. we can imagine cold and hungry men seeking shelter from storms in rocky hollows, where sheep were huddled. how warm the woolly coats of these animals felt to their human fellow-creatures crowded in with them in the dark! it is believed that the primitive men who used stone axes as implements and weapons, learned to use horses to aid them in their hunting, and in their warfare with beasts and other men. gradually these useful animals were adapted to different uses; and at length different breeds were evolved. climate and food supply had much to do with the size and the character of the breeds. in the shetland islands the animals are naturally dwarfed by the cold, bleak winters, and the scant vegetation on which they subsist. in middle europe, where the summers are long and the winters mild, vegetation is luxurious, and the early horses developed large frames and heavy muscles. the shetland pony and the percheron draught-horse are the two extremes of size. what man has done in changing the types of horses is to emphasize natural differences. the offspring of the early heavy horses became heavier than their parents. the present draught-horse was produced, after many generations, all of which gradually approached the type desired. the slender racehorses, bred for speed and endurance rather than strength, are the offspring of generations of parents that had these qualities strongly marked. hence came the english thoroughbred and the american trotter. we can read in books the history of breeds of horses. our knowledge of what horses were like in prehistoric times is scant. it is written in layers of rock that are not very deep, but are uncovered only here and there, and only now and then seen by eyes that can read the story told by fossil skeletons of horses of the ages long past. geologists have unearthed from time to time skeletons of horses. it was professor marsh who spent so much time in studying the wonderful beds of fossil mammals in the western part of this country, and found among them the skeletons of many species of horses that lived here with camels and elephants and rhinoceroses and tigers, long before the time of man's coming. how can any one know that these bones belonged to a horse's skeleton? because some of them are like the bones of a modern horse. it is an easy matter for a student of animal anatomy to distinguish a horse from a cow by its bones. the teeth and the foot are enough. these are important and distinguishing characters. it is by peculiarities in the formation of the bones of the foot that the different species of extinct horses are recognized by geologists. wild horses still exist in the wilds of russia. remains of the same species have been dug out of the soil and found in caves in rocky regions. deeper in the earth are found the bones of horses differing from those now living. the bones of the foot indicate a different kind of horse--an unknown species. but in the main features, the skeleton is distinctly horse-like. in rocks of deeper strata the fossil bones of other horses are found. they differ somewhat from those found in rocks nearer the surface of the earth, and still more from those of the modern horse. the older the rocks, the more the fossil horse differs from the modern. could you think of a more interesting adventure than to find the oldest rocks that show the skeletons of horses? the foot of a horse is a long one, though we think of it as merely the part he walks on. a horse walks on the end of his one toe. the nail of the toe we call the "hoof." the true heel is the hock, a sharp joint like an elbow nearly half way up the leg. along each side of the cannon, the long bone of this foot, lies a splint of bone, which is the remnant of a toe, that is gradually being obliterated from the skeleton. these two splints in the modern horse's foot tell the last chapter of an interesting story. the earliest american horse, the existence of which is proved by fossil bones, tells the first chapter. the story has been read backward by geologists. it is told by a series of skeletons, found in successive strata of rock. the "bad lands" of the arid western states are rich in fossil remains of horses. below the surface soil lie the rocks of the quaternary period, which included the drift laid down by the receding glaciers and the floods that followed the melting of the ice-sheet. under the quaternary lie the tertiary rocks. these comprise three series, called the eocene, miocene, and pliocene, the eocene being the oldest. in the middle region of north america, ponds and marshy tracts were filled in during the tertiary period, by sediment from rivers; and in these beds of clay and other rock débris the remains of fresh-water and land animals are preserved. raised out of water, and exposed to erosive action of wind and water, these deposits are easily worn away, for they have not the solidity of older rocks. they are the crumbly bad lands of the west, cut through by rivers, and strangely sculptured by wind and rain. here the fossil horses have been found. _eohippus_, the dawn horse, is the name given a skeleton found in in the lower eocene strata in wyoming. this specimen lay buried in a rock formation ages older than that in which the oldest known skeleton of this family had been found. its discovery made a great sensation among scientists. this little animal, the skeleton of which is no larger than that of a fox, had four perfect toes, and a fifth splint on the forefoot, and three toes on the hind foot. the teeth are herbivorous. _orohippus_, with a larger skeleton, was found in the middle eocene strata of wyoming. its feet are like those of its predecessor, except that the splint is gone. the teeth as well as the feet are more like those of the modern horse. _mesohippus_, the three-toed horse, found in the miocene, shows the fourth toe reduced to splints, and the skeleton as big as that of a sheep. in this the horse family becomes fairly established. _hypohippus_, the three-toed forest horse, found in the middle miocene strata of colorado, is a related species, but not a direct ancestor of the modern horse. _neohipparion_, the three-toed desert horse, from the upper miocene strata, shows the three toes still present. but the pliocene rocks contain fossils showing gradual reduction of the two side toes, modification of the teeth, and increase in size of the skeleton. _protohippus_ and _pliohippus_, the one-toed species from the pliocene strata, illustrate these changes. they were about the size of small ponies. _equus_, the modern horse, was represented in the pliocene strata by a species, now extinct, called _equus scotti_. this we may regard as the true wild horse of america, for it was as large as the domesticated horse, and much like it, though more like a zebra in some respects. no one can tell why these animals, once abundant in this country, became extinct at the end of the tertiary period. but this is undoubtedly true. the types described form a series showing how the ancestors of the modern horse, grazing on the marshy borders of ancient ponds, lived and died, generation after generation, through a period covering thousands, possibly millions, of years. along the sides of the crumbling buttes these ancient burying-grounds are being uncovered. within a dozen years several expeditions, fitted out by the american museum of natural history, have searched the out-cropping strata in dakota and wyoming for bones of mammals known to have lived at the time the strata were forming in the muddy shallows along the margins of lake and marsh. duplicate skeletons of the primitive horse types above have been found, and vast numbers of their scattered bones. each summer geological excursions will add to the wealth of fossils of this family collected in museums. the tertiary rocks in europe yield the same kind of secrets. the region of paris overlies the estuary of an ancient river. when the strata are laid bare by the digging of foundations for buildings, bones are found in abundance. cuvier was a famous french geologist who made extensive studies of the remains of the prehistoric animals found in this old burial-place called by scientists the paris basin. he believed that the dead bodies floated down-stream and accumulated in the mud of the delta, where the tide checked the river's current. skeletons of the hipparion, a graceful, three-toed horse, were found in numbers in the strata of the miocene time. this animal lived in europe while the pliohippus and the protohippus were flourishing in america. a great number of species of tapir-like animals left their bones in the paris basin, among them a three-hoofed animal which may have been the connecting link between the horse and the tapir families. cuvier found the connecting link between tapirs and cud-chewing mammals. the age of man the hairy, woolly mammoth was one of the giant mammals that withstood the cold of the great ice flood, when the less hardy kinds were cut off by the changing climate of the northern half of europe and america. in caves where the wild animals took refuge from their enemies, skeletons of men have been found with those of the beasts. with these chance skeletons have been found rude, chipped stone spear-heads, hammers, and other tools. with these the savage ancestors of our race defended themselves, and preyed on such animals as they could use for food. they hunted the clumsy mammoth successfully, and shared the caverns in the rocks with animals like the hyena, the sabre-toothed tiger, and the cave bear, which made these places their homes. in california a human skull was found in the bed of an ancient river, which was buried by a lava flow from craters long ago extinct. with this buried skull a few well-shaped but rough stone tools were found. this man must have lived when the great ice flood was at its height. in southern france, caves have been opened that contained bones and implements of men who evidently lived by fishing and hunting. bone fish-hooks showed skill in carving with the sharp edges of flint flakes. a spirited drawing of a mammoth, made on a flat, stone surface, is a proof that savage instincts were less prominent in these cave men than in those who fought the great reindeer and the mammoth farther north. in later times men of higher intelligence formed tribes, tamed the wild horse, the ox, and the sheep, and made friends with the dog. great heaps of shells along the shores show where the tribes assembled at certain times to feast on oysters and clams. bones of animals used as food, and tools, are found in these heaps, called "kitchen-middens." these are especially numerous in northern europe. the stone implements used by these tribes were smoothly polished. a higher intelligence expressed itself also by the making of utensils out of clay. this pottery has been found in shell heaps. so the rude cave man, who was scarcely less a wild beast than the animals which competed with him for a living and a shelter from storms and cold, was succeeded by a higher man who brought the brutes into subjection by force of will and not by physical strength. the lake-dwellers, men of the bronze age, built houses on piles in the lakes of central europe. about sixty years ago the water was low, and these relics of a vanished race were first discovered. the lake bottoms were scraped for further evidences of their life. tools of polished stone and of bronze were taken up in considerable numbers. stored grains and dried fruits of several kinds were found. ornamental trinkets, weapons of hunters and warriors, and agricultural tools tell how the people lived. their houses were probably built over the water as a means of safety from attack of beasts or hostile men. in our country the mound-builders have left the story of their manners of life in the spacious, many-roomed tribal houses, built underground, and left with a great variety of relics to the explorers of modern times. these people worked the copper mines, and hammered and polished lumps of pure metal into implements for many uses. with these are tools of polished stone. stores of corn were found in many mounds scattered in the mississippi valley. the cliff-dwellers of the mesas of arizona and new mexico had habits like those of the mound-builders, and the aztecs, a vanished race in the southwest, at whose wealth and high civilization the invading spaniards under cortez marvelled. the plastered stone houses of the cliff-dwelling indians had many stories and rooms, each built to house a tribe, not merely a family. the pueblo, the moqui, and the zuni indians build similar dwellings to-day, isolated on the tops of almost inaccessible mesas. millions of years have passed since life appeared on the earth. gradually higher forms have followed lower ones in the sea and on the land. but not all of the lower forms have gone. all grades of plants and animals still flourish, but the dominant class in each age is more highly organized than the class that ruled the preceding age. to discover the earth's treasure, and to turn it to use; to tame wild animals and wild plants, and make them serve him; to create ever more beautiful and more useful forms in domestication; to find out the earth's life story, by reading the pages of the great stone book--these are undertakings that waited for man's coming. * * * * * part ii the sky * * * * * every family a "star club" the best family hobby we have ever had is the stars. we have a star club with no dues to pay, no officers to boss us, and only three rules: . we shall have nothing but "fun" in this club--no hard work. therefore no mathematics for us! . we can't afford a telescope. therefore we must be satisfied with what bright eyes can see. . no second-hand wonders for us! we want to see the things ourselves, instead of depending on books. you can't imagine what pleasure we have had in one short year! the baby, of course, was too young to learn anything, and besides he was in bed long before the stars came out. but ruth, our seven-year-old, knows ten of the fifteen brightest stars; and she can pick out twelve of the most beautiful groups or constellations. we grown-ups know all of the brightest stars, and all forty-eight of the most famous constellations. and the whole time we have given to it would not exceed ten minutes a day! and the best part is the _way_ we know the stars. the sky is no longer bewildering to us. the stars are not cold, strange, mysterious. they are friends. we know their faces just as easily as you know your playmates. for instance, we know sirius, because he is the brightest. we know castor and pollux, because they are twins. we know regulus, because he is in the handle of the sickle. and some we know by their colours. they are just as different as president taft, "ty" cobb, horace fletcher and maude adams. and quite as interesting! what's more, none of us can ever get lost again. no matter what strange woods or city we go to, we never get "turned around." or if we do, we quickly find the right way by means of the sun or the stars. then, too, our star club gives us all a little exercise when we need it most. winter is the time when we all work hardest and have the fewest outdoor games. winter is also the best time for young children to enjoy the stars, because it gets dark earlier in winter--by five o'clock, or long before children go to bed. it is pleasant to go out doors for half an hour before supper and learn one new star or constellation. again, it is always entertaining because every night you find the old friends in new places. no two nights are just the same. the changes of the moon make a great difference. some nights you enjoy the moonlight; other nights you wish there were no moon, because it keeps you from spying out some new star. we have a little magazine that tells us all the news of the stars and the planets and the comets _before_ the things happen! we pay a dollar a year for it. it is called the _monthly evening sky map_. when we first became enthusiastic about stars, the father of our family said: "well, i think our star club will last about two years. i judge it will cost us about two dollars and we shall get about twenty dollars worth of fun out of it." but in all three respects father was mistaken. part of the two dollars father spoke of went for a book called "the friendly stars," and seventy-five cents we spent for the most entertaining thing our family ever bought--a planisphere. this is a device which enables us to tell just where any star is, at any time, day or night, the whole year. it has a disc which revolves. all we have to do is to move it until the month and the day come right opposite the very hour we are looking at it, and then we can tell in a moment which stars can be seen at that time. then we go down the street where there is a good electric light at the corner and we hold our planisphere up, almost straight overhead. the light shines through, so that we can read it, and it is just as if we had a map of the heavens. we can pick out all the interesting constellations and name them just as easily as we could find the great lakes or rocky mountains in our geography. we became so eager not to miss any good thing that father got another book. every birthday in our family brought a new star book, until now we have about a dozen--all of them interesting and not one of them having mathematics that children cannot understand. so i think we have spent on stars fifteen dollars more than we needed to spend (but i'm glad we did it), and i think we have had about two hundred dollars worth of fun! yes, when i think what young people spend on ball games, fishing, tennis, skating, and all the other things that children love, i am sure our family has had about two hundred dollars worth of fun out of stars. and there is more to come! you would laugh to know why i enjoy stars so much. i have always studied birds and flowers and trees and rocks and shells so much that i was afraid to get interested in stars. i thought it wouldn't rest me. but it's a totally different kind of science from any i ever studied! there are no families, genera, and species among the stars, thank heaven! that's one reason they refresh me. another is that no one can press them and put them in a herbarium, or shoot them and put them in a museum. and another thing about them that brings balm to my spirit is that no human being can destroy their beauty. no one can "sub-divide" capella and fill it with tenements. no one can use vega for a bill-board. ah, well! we must not be disturbed if every member of our family has a different point of view toward the stars; we can all enjoy and love them in our own ways. how would you like to start a star club like ours? you ought to be able to persuade your family to form one, because it need not cost a cent. perhaps this book will interest them all, but the better way is for you to read about one constellation and then go out with some of the family and find it. this book does not tell about wonderful things you can never see; it tells about the wonderful things all of us can see. i wish you success with your star club. perhaps your uncles and aunts will start clubs, too. we have three star clubs in our family--one in new york, one in michigan, and one in colorado. last winter the "colorado star gazers" sent this challenge to the "new jersey night-owls:" "_we bet you can't see venus by daylight!_" that seemed possible, because during that week the "evening star" was by far the brightest object in the sky. but father and daughter searched the sky before sunset in vain, and finally we had to ask the "moonstruck michiganders" how to see venus while the sun was shining. back came these directions on a postal-card: "wait until it is dark and any one can see venus. then find some tree, or other object, which is in line with venus and over which you can just see her. put a stake where you stand. next day go there half an hour before sunset, and stand a little to the west. you will see venus as big as life. the next afternoon you can find her by four o'clock. and if you keep on you will see her day before yesterday!" that was a great "stunt." we did it; and there are dozens like it you can do. and that reminds me that father was mistaken about our interest lasting only two years. we know that it will not die till we do. for, even if we never get a telescope, there will always be new things to see. our club has still to catch algol, the "demon's eye," which goes out and gleams forth every three days, because it is obscured by some dark planet we can never see. and we have never yet seen mira the wonderful, which for some mysterious reason dies down to ninth magnitude and then blazes up to second magnitude every eleventh month. ah, yes, the wonders and the beauties of astronomy ever deepen and widen. better make friends with the stars now. for when you are old there are no friends like old friends. the dippers and the pole star i never heard of any boy or girl who didn't know the big dipper. but there is one very pleasant thing about the dipper which children never seem to know. with the aid of these seven magnificent stars you can find all the other interesting stars and constellations. so true is this that a book has been written called "the stars through a dipper." to illustrate, do you know the _pointers_? i mean the two stars on the front side of the dipper. they point almost directly toward the pole star, or north star, the correct name of which is polaris. most children can see the pole star at once because it is the only bright star in that part of the heavens. but if you can't be sure you see the right one, a funny thing happens. your friend will try to show you by pointing, but even if you look straight along his arm you can't always be sure. and then, if he tries to tell you how far one star is from another, he will try to show you by holding his arms apart. but that fails also. and so, we all soon learn the easiest and surest way to point out stars and measure distances. the easiest way to tell any one how to find a star is to get three stars in a straight line, or else at right angles. the surest way to tell any one how far one star is from another is by "degrees." you know what degrees are, because every circle is divided into of them. and if you will think a moment, you will understand why we can see only half the sky at any one time, or degrees, because the other half of the sky is on the other side of the earth. therefore, if you draw a straight line from one horizon, clear up to the top of the sky and down to the opposite horizon, it is degrees long. and, of course, it is only half that distance, or degrees, from horizon to zenith. (horizon is the point where earth and sky seem to meet, and zenith is the point straight over your head.) now ninety degrees is a mighty big distance in the sky. the pole star is nothing like ninety degrees from the dipper. it is only twenty-five degrees, or about five times the distance between the pointers. and now comes the only thing i will ask you to remember. look well at the two pointers, because the distance between them, five degrees, is the most convenient "foot rule" for the sky that you will ever find. most of the stars you will want to talk about are from two to five times that distance from some other star that you and your friends are sure of. perhaps this is a little hard to understand. if so, read it over several times, or get some one to explain it to you, for when you grasp it, it will unlock almost as many pleasures as a key to the store you like the best. now, let's try our new-found ruler. let us see if it will help us find the eighth star in the dipper. that's a famous test of sharp eyes. i don't want to spoil your pleasure by telling you too soon where it is. perhaps you would rather see how sharp your eyes are before reading any further. but if you can't find the eighth star, i will tell you where to look. look at the second star in the dipper, counting from the end of the handle. that is a famous star called mizar. now look all around mizar, and then, if you can't see a little one near it, try to measure off one degree. to do this, look at the pointers and try to measure off about a fifth of the distance between them. then look about one degree (or less) from mizar, and i am sure you will see the little beauty--its name is alcor, which means "the cavalier" or companion. the two are sometimes called "_the horse and rider_"; another name for alcor is saidak, which means "the test." i shall be very much disappointed if you cannot see saidak, because it is not considered a hard test nowadays for sharp eyes. aren't these interesting names? mizar, alcor, saidak. they sound so arabian, and remind one of the "arabian nights." at first, some of them will seem hard, but you will come to love these old names. i dare say many of these star names are , years old. shepherds and sailors were the first astronomers. the sailors had to steer by the stars, and the shepherds could lie on the ground and enjoy them without having to twist their necks. they saw and named alcor, thousands of years before telescopes were invented, and long before there were any books to help them. they saw the demon star, too, which i have never seen. it needs patience to see those things; sharp eyes are nothing to be proud of, because they are given to us. but patience is something to be eager about, because it costs us a lot of trouble to get it. let's try for it. we've had a test of sight. now let's have a test of patience. it takes more patience than sharpness of sight to trace the outline of the little dipper. it has seven stars, too, and the pole star is in the end of the handle. do you see two rather bright stars about twenty-five degrees from the pole? i hope so, for they are the only brightish stars anywhere near polaris. well, those two stars are in the outer rim of the little dipper. now, i think you can trace it all; but to make sure you see the real thing, i will tell you the last secret. the handle of the big dipper is bent _back_; the handle of the little dipper is bent _in_. now, if you have done all this faithfully, you have worked hard enough, and i will reward you with a story. once upon a time there was a princess named callisto, and the great god jupiter fell in love with her. naturally, jupiter's wife, juno, wasn't pleased, so she changed the princess into a bear. but before this happened, callisto became the mother of a little boy named arcas, who grew up to be a mighty hunter. one day he saw a bear and he was going to kill it, not knowing that the bear was really his own mother. luckily jupiter interfered and saved their lives. he changed arcas into a bear and put both bears into the sky. callisto is the big bear, and arcas is the little bear. but juno was angry at that, and so she went to the wife of the ocean and said, "please, never let these bears come to your home." so the wife of the ocean said, "i will never let them sink beneath the waves." and that is why the big and the little dipper never set. they always whirl around the pole star. and that is why you can always see them, though some nights you would have to sit up very late. is that a true story? no. but, i can tell you a true one that is even more wonderful. once upon a time, before the bear story was invented and before people had tin dippers, they used to think of the little dipper as a little dog. and so they gave a funny name to the pole star. they called it cynosura, which means "the dog's tail." we sometimes say of a great man, "he was the cynosure of all eyes," meaning that everybody looked at him. but the original cynosure was and is the pole star, because all the stars in the sky seem to revolve around it. the two dippers chase round it once every twenty-four hours, as you can convince yourself some night when you stay up late. so that's all for to-night. what! you want another true story? well, just one more. once upon a time the big dipper was a perfect cross. that was about , years ago. fifty thousand years from now the big dipper will look like a steamer chair. how do i know that? because, the two stars at opposite ends of the dipper are going in a direction different from the other five stars. how do i know that? why, i don't know it. i just believe it. there are lots of things i don't know, and i'm not afraid to say so. i hope you will learn how to say "i don't know." it's infinitely better than guessing; it saves trouble, and people like you better, because they see you are honest. i don't know how the stars in the big dipper are moving, but the men who look through telescopes and study mathematics say the end stars do move in a direction opposite to the others, and they say the dipper _must_ have looked like a cross, and will look like a dipper long, long after we are dead. and i believe them. constellations you can always see there are forty-eight well known constellations, but of these only about a dozen are easy to know. i think a dozen is quite enough for children to learn. and therefore, i shall tell you how to find only the showiest and most interesting. the best way to begin is to describe the ones that you can see almost every night in the year, because you may want to begin any month in the year, and you might be discouraged if i talked about things nobody could see in that month. there are five constellations you can nearly always see, and these are all near the pole star. doubtless you think you know two of them already--the big and the little dipper. ah, i forgot to tell you that these dippers are not the real thing. they are merely parts of bigger constellations and their real names are great bear and little bear. the oldest names are the right ones. thousands of years ago, when the greeks named these groups of stars, they thought they looked like two bears. i can't see the resemblance. but for that matter all the figures in the sky are disappointing. the people who named the constellations called them lions, and fishes, and horses, and hunters, and they thought they could see a dolphin, a snake, a dragon, a crow, a crab, a bull, a ram, a swan, and other things. but nowadays we cannot see those creatures. we can see the stars plainly enough, and they do make groups, but they do not look like animals. i was greatly disappointed when i was told this; but i soon got over it, because new wonders are always coming on. i think the only honest thing to do is to tell you right at the start that you cannot see these creatures very well. you will spoil your pleasure unless you take these resemblances good-naturedly and with a light heart. and you will also spoil your pleasure if you scold the ancients for naming the constellations badly. nobody in the world would change those old names now. there is too much pleasure in them. besides, i doubt if we could do much better. i believe those old folks were better observers than we. and i believe they had a lighter fancy. let us, too, be fanciful for once. i have asked my friend, mrs. thomas, to draw her notion of some of these famous creatures of the sky. you can draw your idea of them too, and it is pleasant to compare drawings with friends. there is only one way to see anything like a great bear. you have to imagine the dipper upside down and make the handle of the dipper serve for the bear's tail. what a funny bear to drag a long tail on the ground! miss martin says he looks more like a chubby hobby-horse. you will have to make the bowl of the dipper into hind legs and use all the other stars, somehow, to make a big, clumsy, four-legged animal. and what a monster he is! he measures twenty-five degrees from the tip of his nose to the root of his tail. yes, all those miscellaneous faint stars you see near the big dipper belong to the great bear. [illustration: orion fighting the bull. above are orion's two dogs] [illustration: the little bear, the queen in her chair, the twins and the archer] how the great bear looked to the people who named it thousands of years ago, we probably shall never know. they left no books or drawings, so far as i know. but in every dictionary and book on astronomy you can find these bears and other animals drawn so carefully and beautifully that it seems as if they _must_ be in the sky, and we must be too dull to see them. it is not so. look at the pictures in this book and, you will see that the stars do not outline the animals. many of them come at the wrong places. and so it is with all the costly books and charts and planispheres. it is all very interesting, but it isn't true. it's just fancy. and when you once understand that it isn't true, you will begin to enjoy the fancy. many a smile you will have, and sometimes a good laugh. for instance, the english children call the dipper "charles's wain" or "the wagon." and the romans called it "the plough." they thought of those seven stars as oxen drawing a plough. well, that's enough about the two bears. i want to tell you about the other three constellations you can nearly always see. these are the chair, the charioteer, and perseus (pronounced _per'soos_). the chair is the easiest to find, because it is like a very bad w, and it is always directly opposite the big dipper, with the pole star half way between the two constellations. there are five stars in the w, and to make the w into a chair you must add a fainter star which helps to make the square bottom of the chair. but what a crazy piece of furniture! i have seen several ways of drawing it, but none of them makes a comfortable chair. i should either fall over backward, or else the back of the chair would prod me in the small of my back. the correct name of this constellation is cassiopeia's chair. i think this is enough to see and enjoy in one night. to-morrow night let us look for the charioteer. i love the charioteer for several reasons. one is that it makes a beautiful pentagon, or five-sided figure, with its five brightest stars. another is that it contains the second-brightest star in the northern part of the heavens, capella. the only star in the north that is brighter is vega, but vega is bluish white or creamy. if you haven't already found the five-sided figure, i will tell you how to find capella. suppose you had a gun that would shoot anything as far as you wish. shoot a white string right through the pointers and hit the pole star. then place your gun at the pole star and turn it till it is at right angles to that string you shot. aim away from the big dipper, shoot a bullet forty-five degrees and it will hit capella. if that plan doesn't work, try this. start with the star that is at the bottom of the dipper and nearest the handle. draw a line half-way between the two pointers and keep on till you come to the first bright star. this is capella, and the distance is about fifty degrees. capella means "a kid," or "little goat," and that reminds me of the third reason why i enjoy so much the constellation of which capella is the brightest star. in the old times they sometimes called this five-sided figure "the goat-carrier." and the shepherds thought they could see a man carrying a little goat in his left hand. i am sure you can see the kid they meant. it is a triangle of faint stars which you see near capella. that's enough for to-night. to-morrow night let us look for perseus. i dare say you know that old tale about perseus rescuing the princess who was chained upon a rock. (he cut off the snaky head of medusa and showed it to the dragon that was going to devour the princess, and it turned the monster to stone. remember?) well, there are constellations named after all the people in that story, but although they contain many showy stars, i could never make them look like a hero, a princess, a king, and a queen. i do not even try to trace out all of perseus. for i am satisfied to enjoy a very beautiful part of it which is called the "arc of perseus." an arc, you know, is a portion of a circle. and the way to find this arc is to draw a curve from capella to cassiopeia. on nights that are not very clear i can see about seven stars in this arc of perseus. and the reason i love it so much is that it is the most beautiful thing, when seen through an opera-glass, that i know. you could never imagine that a mere opera-glass would make such a difference. the moment i put it to my eyes about a dozen more stars suddenly leap into my sight in and near the arc of perseus. that's enough. no more stories to-night. winter constellations by winter constellations i mean those you can see in winter at the pleasantest time--the early evening. and i want you to begin with the northern cross. i hope you can see this before christmas, for, after that, it may be hidden by trees or buildings in the west and you may not see it again for a long while. this is because the stars seem to rise in the east and set in the west. to prove this, choose some brilliant star you can see at five or six o'clock; get it in line with some bush or other object over which you can just see it. put a stake where you stand, and then go to the same spot about eight o'clock or just before you go to bed. you can tell at once how much the star seems to have moved westward. another thing, every star rises four minutes later every night, and therefore the sky looks a little different at the same hour every evening. the stars in the north set for a short time only, but when those toward the south set they are gone a long time. for instance, the brightest star of all is sirius, the dog star, which really belongs to the southern hemisphere. there are only about three months in the year when children who go to bed by seven o'clock can see it--january, february, and march. so now you understand why i am so eager that you should not miss the pleasure of seeing the famous northern cross. but although it is a big cross, and easy to find, after you know it, i have never yet known a boy who could show it to another boy simply by pointing at it. the surest and best way to find it is learn three bright stars first--altair, vega, and deneb. altair is the brightest star in the milky way. it is just at the edge of the milky way, and you are to look for three stars in a straight line, with the middle one brightest. those three stars make the constellation called "the eagle." the body of the eagle is altair, and the other two stars are the wings. i should say that altair is about five degrees from each of his companions. it is worth half an hour's patient search to find the eagle. now these three stars in the eagle point straight toward the brightest star in the northern part of the sky--vega. to make sure of it, notice four fainter stars near it which make a parallelogram--a sort of diamond. these stars are all part of a constellation called "the lyre." if you try to trace out the old musical instrument, you will be disappointed; but here is a game worth while. can you see a small triangle made by three stars, of which vega is one? well, one of those stars is double, and with an opera-glass you can see which it is. on very clear nights some people with very sharp eyes can see them lying close together, but i never could. at last we are ready to find the celebrated northern cross. first draw a line from altair to vega. then draw a line at right angles to this, until you come to another bright star--deneb--which is about as far from vega as vega is from altair. now this beautiful star, deneb, is the top of the northern cross. i can't tell you whether the cross will be right or wrong side up when you see it, or on its side. for every constellation is likely to change its position during the night, as you know from watching the dipper. but you can tell the cross by these things. there are six stars in it. it is like a kite made of two sticks. there are three stars in the crosspiece and four in the long piece. deneb, the brightest star in the cross, is at the top of the long stick. but you mustn't expect to see a perfect cross. there is one star that is a little out of place, and sometimes my fingers fairly "itch to put it where it belongs." it is the one that ought to be where the long stick of your kite is tacked to the crosspiece. and one of the stars is provokingly faint, but you can see it. counting straight down the long piece, it is the third one from deneb that is faint. it is where it ought to be, but i should like to make it brighter. have you the cross now? if not, have patience. you can't be a "true sport" unless you are patient. you can't be a great ball-player, or hunter, or any thing else, without resisting, every day, that sudden impulse to "quit the game" when you lose. be a "good loser," smile and try again. that is better than to give up, or to win by cheating or sharp practice. this is the last thing i want you to see in the northern part of the sky; and if you have done a good job, let us celebrate by having a story. once upon a time a cross didn't mean so much to the world as it does now. that was before christ was born. in those old times people did not think of the northern cross as a cross. they thought of it as a swan, and you can see the swan if you turn the cross upside down. deneb will then be in the tail of the swan, and the two stars which used to be at the tips of the crosspiece now become the wings. is that a true story? yes. if we lived in arabia the children there could tell us what deneb means. it means "the tail." another story? well, do you see the star in the beak of the swan, or foot of the cross? what color is it? white? well, they say this white star is really made up of two stars--one yellow and the other blue. that is one reason i want to buy a telescope when i can afford it, for even the smallest telescope will show that. and mr. serviss says that even a strong field-glass will help any one see this wonder. i can't tell you about all the winter constellations in one chapter. we have made friends of the northern ones. now let's see the famous southern ones. and let's start a new chapter. orion, his dogs, and the bull the most gorgeous constellation in the whole sky is orion. i really pity any one who does not know it, because it has more bright stars in it than any other group. besides, it doesn't take much imagination to see this mighty hunter fighting the great bull. i dare say half the people in the united states know orion and can tell him as quick as they see him by the famous "belt of orion." this belt is made of three stars, each of which is just one degree from the next. that is why the english people call these three stars "the ell and yard." another name for them is "the three kings." you can see the "sword of orion" hanging down from his belt. as soon as you see these things you will see the four bright stars that outline the figure of the great hunter, but only two of them are of the first magnitude. the red one has a hard name--betelgeuse (pronounced _bet-el-guz´_). that is a frenchified word from the arabic, meaning "armpit," because this star marks the right shoulder of orion. the other first-magnitude star is the big white one in the left foot. its name is rigel (pronounced _re´-jel_) from an arabian word meaning "the foot." you can see the giant now, i am sure. over his left arm hangs a lion's skin which he holds out to shield him from the bull's horns. see the shield--about four rather faint stars in a pretty good curve? now look for his club which he holds up with his right hand so as to smite the bull. see the arm and the club--about seven stars in a rather poor curve--beyond the red star betelgeuse? now you have him, and isn't he a wonder! it is even easier to see the bull which is trying to gore orion. look where orion is threatening to strike, and you will see a v. how many stars in that v? five. and which is the brightest? that red one at the top of the left branch of the v? yes. that v is the face of the bull and that red star is the baleful eye of the angry bull which is lowering his head and trying to toss orion. the name of that red eye is aldebaran (pronounced _al-deb´-ar-an_). i wish aldebaran meant "red eye," but it doesn't. it is an old arabian word meaning the "hindmost," or the "follower," because every evening it comes into view about an hour after you can see the famous group of stars called the pleiades, which are in the shoulder of the bull. i do not care to trace the outline of this enormous bull, but his horns are a great deal longer than you think at first. if you will extend the two arms of that v a long way you will see two stars which may be called the tips of his horns. one of these stars really belongs in another constellation--our old friend the charioteer, the one including capella. wow! what a pair of horns! but now we come to the daintiest of all constellations--the seven sisters, or pleiades (pronounced _plee´-a-deez_). i can see only six of them, and there is a famous old tale about the "lost pleiad." but i needn't describe them. every child finds them by instinct. some compare them to a swarm of bees; some to a rosette of diamonds; some to dewdrops. but i would not compare them to a dipper as some do, because the real little dipper is very different. the light that seems to drip from the pleiades is quivering, misty, romantic, magical. no wonder many children love the pleiades best of all the constellations. no wonder the poets have praised them for thousands of years. the oldest piece of poetry about them that i know of was written about , years before christ. you can find it in the book of job. but the most poetic description of the pleiades that i have ever read is in tennyson's poem "locksley hall," in which he says they "glitter like a swarm of fireflies tangled in a silver braid." there are a great many old tales about the lost pleiad. one is that she veiled her face because the ancient city of troy was burned. another story says she ceased to be a goddess when she married a man and became mortal. some people think she was struck by lightning. others believe the big star, canopus, came by and ran away with her. still others declare she was a new star that appeared suddenly once upon a time, and after a while faded away. for myself, i do not believe any of these stories. one reason why i don't is that a seventh star is really there, and many people can really see it. indeed, there are some people so sharp-eyed that on clear nights they can see anywhere from eight to eleven. and, what is more, they can draw a map or chart showing just where each star seems to them to be. but the most wonderful stories about the pleiades are the true stories. one is that there are really more than , stars among the pleiades. some of them can be seen only with the biggest telescopes. others are revealed only by the spectroscope. and some can be found only by means of photography. but the most amazing thing about the pleiades is the distances between them. they look so close together that you would probably say "the moon seems bigger than all of them put together." sometimes the moon comes near the pleiades, and you expect that the moon will blot them all out. but the astronomers say the full moon sails through the pleiades and covers only one of them at a time, as a rule. they even say it is possible for the moon to pass through the pleiades without touching one of them! i should like to see that. if anything like it is going to occur, the magazine i spoke of in the first chapter will tell me about it. and you'd better believe i will stay up to see that, if it takes all night! there are two more constellations in the southern part of the sky that ought to be interesting, because they are the two hunting dogs that help orion fight the bull. but i can't trace these animals, and i don't believe it is worth while. the brightest stars in them everybody can see and admire--sirius, the bigger dog, and procyon, the smaller dog. every one ought to know sirius, because he is the brightest star of all. (of course, he is not so bright as venus and jupiter, but they are planets.) to find him, draw a line from the eye of the bull through the belt of orion and extend it toward the southeast about twenty degrees. they call him the dog star because he follows the heels of orion. and people still call the hottest days of summer "dog days" because years before christ the romans noticed that the dog star rose just before the sun at that time. the romans thought he chased the sun across the sky all day and therefore was responsible for the great heat. but that was a foolish explanation. and so is the old notion that dogs are likely to go mad during the dog days "because the dog star is in the ascendant." so is the idea that sirius is an unlucky star. there are no lucky or unlucky stars. these are all superstitions, and we ought to be ashamed to believe any superstition. yet for thousands of years before we had public schools and learned to know better, people believed that every one was born under a lucky star or an unlucky one, and they believe that farmers ought to plant or not plant, according to the size of the moon. now we know that is all bosh. those old superstitions have done more harm than good. one of the most harmful was the belief in witches. let us resolve never to be afraid of these old tales, but laugh at them. why should anybody be afraid of anything so lovely as sirius? i used to think sirius twinkled more than any other star. but that was bad reasoning on my part. i might have noticed that every star twinkles more near the horizon than toward the zenith. i might have noticed that stars twinkle more on clear, frosty nights than when there is a little uniform haze. and putting those two facts together i might have reasoned that the stars never really twinkle at all; they only seem to. i might have concluded that the twinkling is all due to the atmosphere--that blanket of air which wraps the earth around. the nearer the earth, the thicker the air, and the more it interferes with the light that comes to us from the stars. they say that sirius never looks exactly alike on two successive nights. "it has a hundred moods," says mr. serviss, "according to the state of the atmosphere. by turns it flames, it sparkles, it glows, it blazes, it flares, it flashes, it contracts to a point, and sometimes when the air is still, it burns with a steady white light." (quotation somewhat altered and condensed.) it is a pity that so fine a star as procyon should be called the "smaller dog," because it suffers unjustly by comparison with sirius. if it were in some other part of the sky we might appreciate it more, because it is brighter than most of the fifteen first-magnitude stars we can see. my brother william has grown to love it, but perhaps that is because he always "sympathizes with the under dog." he was the youngest brother and knows. and curiously enough he was nicknamed "the dog"--just why, i don't know. to find procyon, drawn a line from sirius northeast about twenty degrees. and to make sure, draw one east from betelgeuse about the same distance. these three stars make a triangle of which the sides are almost equal. the name procyon means "before the dog" referring to the fact that you can see him fifteen or twenty minutes earlier every night than you can see sirius. the only kind word about procyon i have heard in recent years was in connection with that miserable business of dr. cook and the north pole. a captain somebody-or-other was making observations for dr. cook, and he wanted to know what time it was. he had no watch and didn't want to disturb any one. so he looked out of the window and saw by the star procyon that it was eleven o'clock. that sounds mysterious, but it is easy if you have a planisphere like ours. last winter when we were all enjoying orion, the bull, and the two dogs, i used to whirl the planisphere around to see where they would be at six o'clock at night, at eight, at ten, at midnight, and even at six o'clock in the morning. and so, if i waked up in the night i could tell what time it was without even turning my head. sometimes i looked out of my window, saw orion nearly overhead and knew it must be midnight. and sometimes i woke up just before daybreak and saw the great bull backing down out of sight in the west, the mighty hunter still brandishing his club, and his faithful dogs following at his heels. seven famous constellations there are only seven more constellations that seem to me interesting enough for every one to know and love all his life. these are: the lion (spring) the twins (spring) the virgin (summer) the herdsman (summer) the northern crown (summer) the scorpion (summer) southern fish (autumn) i have named the seasons when, according to some people, these constellations are most enjoyable. but these are not the only times when you can see them. (if you had that seventy-five-cent planisphere, now, you could always tell which constellations are visible and just where to find them.) no matter what time of year you read this chapter, it is worth while to go out and look for these marvels. you can't possibly miss them all. have you ever seen a sickle in the sky? it's a beauty, and whenever i have seen it it has been turned very conveniently for me, because i am left-handed. it is so easy to find that i am almost ashamed to tell. but if you need help, draw a line through the pointers backward, away from the pole star, about forty degrees, and it will come a little west of the sickle. the sickle is only part of the lion--the head and the forequarters. only fanciful map-makers can trace the rest of the lion. the bright star at the end of the handle is regulus, which means "king," from the stupid old notion that this star ruled the lives of men. to this day people speak of the "royal star," meaning regulus. and at the end of this chapter i will tell you about three other stars which the persians called "royal stars." another constellation which children particularly love is the twins--castor and pollux. but the sailors got there first! for thousands of years the twins have been supposed to bring good luck to sailors. i don't believe a word of it. but i do know that sailors gloat over castor and pollux, and like them better than any other stars. the whole constellation includes all the stars east of the bull and between the charioteer and procyon. but another way to outline the twins is to look northeast of orion where you will see two rows of stars that run nearly parallel. to me the brothers seem to be standing, but all the old picture-makers show them sitting with their arms around each other, the two brightest stars being their eyes. the eyes are about five degrees apart--the same as the pointers. pollux is now brighter than castor, but for thousands of years it was just the other way. it is only within three hundred years that this change has taken place. whether castor has faded or pollux brightened, or both, i do not know. anyhow, castor is not quite bright enough to be a first magnitude star. three hundred years is a short time in the history of man, and only a speck in the history of the stars. three hundred years ago they killed people in europe just because of the church they went to. that was why the pilgrim fathers sailed from england in , and made the first permanent settlement in america, except, of course, jamestown, va., in . there are plenty of stories about old castor and pollux, and, like all the other myths, they conflict, more or less. but all agree that these two brothers went with jason in the ship argo, shared his adventures and helped him get the golden fleece. and all agree that castor and pollux were "born fighters." and that is why the roman soldiers looked up to these stars and prayed to them to help them win their battles. now for the four summer constellations every one ought to know. the first thing to look for is two famous red or reddish stars--arcturus and antares. the way you find arcturus is amusing. look for the big dipper and find the star at the bottom of the dipper nearest the handle. got it? now draw a curve that will connect it with all the stars in the handle, and when you come to the end of the handle keep on till you come to the first very bright star--about twenty-five degrees. that is the monstrous star arcturus, probably the biggest and swiftest star we can ever see with the naked eye in the northern hemisphere. he is several times as big as our sun, and his diameter is supposed to be several million miles. he is called a "runaway sun," because he is rushing through space at the rate of between two hundred and three hundred miles a second. that means between seventeen and thirty-four million miles a day! he is coming toward us, too! at such a rate you might think that arcturus would have smashed the earth to pieces long ago. but he is still very far away, and there is no danger. some people say that if job were to come to life, the sky would seem just the same to him as it did , years ago. the only difference he might notice would be in arcturus. that would seem to him out of place by a distance about three times the apparent diameter of the moon. some people believe this because job said, "canst thou guide arcturus with his sons?" and therefore they imagine that he meant this red star. but i believe he meant the big dipper. for in king james's time, when the bible was translated into english, the word "arcturus" meant the big dipper or rather the great bear. and for centuries before it meant the great bear. one proof of it is that "arcturus" comes from an old greek word meaning "bear"--the same word from which we get arctic. it is only within a few hundred years that astronomers have agreed to call the great bear "ursa major," and this red star arcturus. so i think all the books which say job mentioned this red star are mistaken. i believe webster's dictionary is correct in this matter, and i believe the revised version translates job's hebrew phrase more correctly when it says, "canst thou guide the bear with her train?" anyhow, arcturus is a splendid star--the brightest in the constellation called the "herdsman" or boötes. it is not worth while to trace the herdsman, but here is an interesting question. is arcturus really red? the books mostly say he is yellow. they say he looks red when he is low in the sky, and yellow when he is high. how does he look to you? more yellow than red? well, there's no doubt about antares being red. to find him, draw a long line from regulus through arcturus to antares, arcturus being more than half way between the other two. but if regulus and the sickle are not visible, draw a line from altair, at right angles to the eagle, until you come to a bright star about sixty degrees away. you can't miss antares, for he is the only red star in that part of the sky. antares belongs to a showy constellation called the scorpion. i cannot trace all the outline of a spider-like creature, but his poisonous tail or "stinger" is made by a curved line of stars south and east of antares. and you can make a pretty fan by joining antares to several stars in a curve which are west of antares and a little north. there is an old tale that this scorpion is the one that stung orion to death when he began to "show off" and boast that there was no animal in the world that could kill him. another very bright star in the southern part of the sky is spica. to find it, start with the handle of the dipper, and making the same backward curve which helped you to find arcturus, keep on till you come to the white star spica--say thirty degrees beyond arcturus. this is the brightest star in the constellation called "the virgin." it is not worth while trying to trace her among nearly forty faint stars in this neighbourhood. but she is supposed to be a winged goddess who holds up in her right hand an _ear of wheat_, and that is what spica means. now for an autumn constellation--the southern fish. i don't care if you fail to outline a fish, but i do want you to see the bright star that is supposed to be in the fish's mouth. and i don't want you to balk at its hard name--fomalhaut (pronounced _fo´-mal-o_). it is worth a lot of trouble to know it as a friend. to find it, you have to draw an exceedingly long line two-thirds of the way across the whole sky. start with the pointers. draw a line through them and the pole star and keep clear on until you come to a solitary bright star rather low down in the south. that is fomalhaut. it looks lonely and is lonely, even when you look at it through a telescope. and now for the last story. once upon a time the persians thought there must be four stars that rule the lives of men. so they picked out one in the north and one in the south and one in the east and one in the west, just as if they were looking for four bright stars to mark the points of the compass. if you want to find them yourself without my help don't read the next sentence, but shut this book and go out and see. then write down on a piece of paper the stars you have selected and compare them with the list i am about to give. here are the four royal stars of the persians: fomalhaut for the north, regulus for the south, aldebaran for the east, and antares for the west. why doesn't this list agree with yours? because persia is so far south of where we live. ah, there are very few things that are absolutely true. let's remember that and not be too sure: for everything depends upon the point of view! i hope you will see fomalhaut before christmas, before he disappears in the west. he is with us only five months and is always low--near the horizon. but the other seven months in the year he gladdens the children of south america and the rest of the southern hemisphere, for they see him sweeping high and lonely far up into their sky and down again. but the loveliest of all the constellations described in this chapter is the northern crown. it is not a perfect crown--only about half a circle--but enough to suggest a complete ring. look for it east of arcturus. i can see seven or eight stars in the half-circle, one of which is brighter than all the others. that one is called "the pearl." the whole constellation is only fifteen degrees long, but "fine things come in small packages"; and children grow to love the northern crown almost as much as they love the pleiades. the twenty brightest stars if you have seen everything i have described so far, you have reason to be happy. for now you know sixteen of the most famous constellations and fifteen of the twenty brightest stars. there are only twenty stars of the first magnitude. "magnitude" ought to mean size, but it doesn't. it means brightness--or rather the apparent brightness--of the stars when seen by us. the word magnitude was used in the old days before telescopes, when people thought the brighter a star is the bigger it must be. now we know that the nearer a star is to us the brighter it is, and the farther away the fainter. some of the bright stars are comparatively near us, some are very far. deneb and canopus are so far away that it takes over three hundred years for their light to reach us. what whoppers they must be--many times as big as our sun. here is a full list of the twenty stars of the first magnitude arranged in the order of their brightness. you will find this table very useful. ----------------+---------------+-------------+-------------------------- stars | pronounced |constellation| interesting facts ----------------+---------------+-------------+-------------------------- sirius | _sir´i-us_ | big dog | brightest star. nearest | | | star visible in northern | | | hemisphere canopus* | _ca-no´pus_ | ship argo | perhaps the largest body | | | in universe alpha centauri* | _al´fa | | | sen-taw´re_ | centaur | nearest star. light four | | | years away vega | _ve´ga_ | lyre | brightest star in the | | | northern sky. bluish capella | _ca-pell´a_ | charioteer | rivals vega, but opposite | | | the pole. yellowish arcturus | _ark-tu´rus_ | herdsman | swiftest of the bright | | | stars. miles a second rigel | _re´jel_ | orion | brightest star in orion. | | | white star in left foot procyon | _pro´si-on_ | little dog | before the dog. rises a | | | little before sirius achernar* | _a-ker´nar_ | river po | means the end of the river beta centauri* | _ba´ta | | | sen-taw´re_ | centaur | this and its mate point to | | | the southern cross altair | _al-tare´_ | eagle | helps you find vega and | | | northern cross betelgeuse | _bet-el-guz´_ | orion | means "armpit." the red | | | star in the right shoulder alpha crucis* | _al´fa | southern | | cru´sis_ | cross | at the base of the most | | | famous southern | | | constellation aldebaran | _al-deb´a-ran_| bull | the red eye in the v pollux | _pol´lux_ | twins | brighter than castor spica | _spi´ca_ | virgin | means ear of wheat antares | _an-ta´rez_ | scorpion | red star. name means | | | "looks like mars" fomalhaut | _fo´mal-o_ | southern | | | fish | the lonely star in the | | | southern sky deneb | _den´eb_ | swan | top of northern cross, | | | or tail of swan regulus | _reg´u-lus_ | lion | the end of the handle | | | of the sickle ----------------+---------------+-------------+-------------------------- the five stars marked * belong to the southern hemisphere, and we can never see them unless we travel far south. last winter i went to florida and saw canopus, but to see the southern cross you should cross the tropic of cancer. how to learn more all i can hope to do in this book is to get you enthusiastic about astronomy. i don't mean "gushy." look in the dictionary and you will find that the enthusiast is not the faddist. he is the one who sticks to a subject for a lifetime. nor do i care a rap whether you become an astronomer--or even buy a telescope. there will be always astronomers coming on, but there are too few people who know and love even a few of the stars. i want you to make popular astronomy a life-long hobby. perhaps you may have to drop it for ten or fifteen years. never mind, you will take up the study again. i can't expect you to read a book on stars if you are fighting to make a living or support a family, unless it really rests you to read about the stars. it does rest me. when things go wrong at the office or at home, i can generally find rest and comfort from music. and if the sky is clear, i can look at the stars, and my cares suddenly seem small and drop away. let me tell you why and how you can get the very best the stars have to teach you, without mathematics or telescope. follow this programme and you need never be afraid of hard work, or of exhausting the pleasures of the subject. go to your public library and get one of the books i recommend in this chapter, and read whatever interests you. i don't care whether you take up planets before comets or comets before planets, but whatever you do do it well. soak the interesting facts right in. nail them down. see everything the book talks about. make notes of things to watch for. get a little blank book and write down the date you first saw each thing of interest. write down the names of the constellations you love most. before you lay down any star book you are reading, jot down the most wonderful and inspiring thing you have read--even if you have only time to write a single word that may recall it all to you. treasure that little note book as long as you live. every year it will get more precious to you. now for the books: . _martin._ _the friendly stars._ harper & brothers, new york, . this book teaches you first the twenty brightest stars and then the constellations. i cannot say that this, or any other, is the "best book," but it has helped me most, and i suppose it is only natural that we should love best the first book that introduces us to a delightful subject. . _serviss._ _astronomy with the naked eye._ harper & brothers, new york, . this teaches you the constellations first and the brightest stars incidentally. also it gives the old myths. . _serviss._ _astronomy with an opera-glass._ d. appleton & co., new york, . . _serviss._ _pleasures of the telescope._ d. appleton & co., new york, . . _milham._ _how to identify the stars._ the macmillan co., new york, . this gives a list of eighty-eight constellations, including thirty-six southern ones, and has tracings of twenty-eight. . _elson._ _star gazer's handbook._ sturgis & walton co., new york, . about the briefest and cheapest. has good charts and makes a specialty of the myths. . _serviss._ _curiosities of the sky._ harper & brothers, new york. tells about comets, asteroids, shooting stars, life on mars, nebulæ, temporary stars, coal-sacks, milky way, and other wonders. . _ball._ _starland._ ginn & co., boston, new york, etc., . this tells about a great many interesting experiments in astronomy that children can make. * * * * * if i had only a dollar or less to spend on astronomy i should buy a planisphere. i got mine from thomas whittaker, no. bible house, new york. it cost seventy-five cents, and will tell you where to find any star at any time in the year. it does not show the planets, however. a planisphere that will show the planets costs about five dollars. however, there are only two very showy planets, viz., venus and jupiter. any almanac will tell you (for nothing) when each of these is morning star, and when each of them is evening star. the best newspaper about stars, as far as i know, is a magazine called _the monthly evening sky map_, published by leon barritt, nassau st., new york. it costs a dollar a year. it gives a chart every month, showing all the planets, and all the constellations. also it tells you about the interesting things, like comets, before they come. good-bye. i hope you will never cease to learn about and love the earth and the sky. perhaps you think you have learned a great deal already. but your pleasures have only begun. wait till you learn about how the world began, the sun and all his planets, the distances between the stars, and the millions of blazing suns amid the milky way! the end [illustration: the sky in winter] note.--these simplified star maps are not as accurate as a planisphere, but they may be easier for children. all star maps are like ordinary maps, except that east and west are transposed. the reason for this is that you can hold a star map over your head, with the pole star toward the north, and the map will then match the sky. these maps contain some constellations that are only for grown-ups to study. the winter constellations every child should know are: auriga, the charioteer canis major, the big dog canis minor, the little dog cassiopeia, the queen in her chair cygnus, the swan leo, the lion orion, the hunter perseus, which has the arc taurus, the bull ursa major, the great bear ursa minor, the little bear [illustration: the sky in spring] note.--once upon a time all the educated people spoke latin. it was the nearest approach to a universal language. so most of the constellations have latin names. the english, french and german names are all different, but if all children would learn the latin names they could understand one another. the spring constellations every child should know are: leo, the lion lyra, the lyre cassiopeia, the queen in her chair scorpio, the scorpion ursa major, the great bear ursa minor, the little bear virgo, the virgin [illustration: the sky in summer] note.--every sky map is good for three months, in this way: if this is correct on june st at p.m., it will be correct july st at p.m., and august st at p.m. this is because the stars rise four minutes earlier every night. thus, after thirty days, any star will rise thirty times four minutes earlier, or minutes, or two hours. children need not learn all the summer constellations. the most interesting are: auriga, the charioteer canis major, the big dog cygnus, the swan lyra, the lyre scorpio, the scorpion [illustration: the sky in autumn] note.--this book tells how to find all the most interesting stars and constellations without maps, but many people prefer them. how to use star maps is explained under "the sky in winter." the autumn constellations most interesting to children are: aquila, the eagle auriga, the charioteer cassiopeia, the queen in her chair cygnus, the swan lyra, the lyre perseus, which has the arc taurus, the bull ursa major, the great bear ursa minor, the little bear transcriber's notes page "streams, runing" corrected to "streams, running" page "where he globe" corrected to "where the globe" page "ceatures to prove" corrected to "creatures to prove" page "this consellation is" corrected to "this constellation is" page "everybirth day" corrected to "every birthday"